JP2007288074A - Organic electroluminescent device and manufacturing method thereof - Google Patents

Abstract

An organic electroluminescent device which operates stably with uniform light emission characteristics and has excellent life characteristics is provided.
At least one set of electrodes and a plurality of functional layers formed between the electrodes are provided, and the functional layers are formed of at least one kind of organic semiconductor and have a light emitting function, and at least a film thickness. Transition metal oxide layer of 30 nm or more.
[Selection] Figure 1

Description

  The present invention relates to an organic electroluminescent device and a method for manufacturing the same, and is particularly used for a display for a mobile phone, a display device, various light sources, and the like, and is driven in a wide luminance range from low luminance to high luminance for a light source. The present invention relates to an organic electroluminescent device that is an electroluminescent device.

  An organic electroluminescent element is a light-emitting device that utilizes the electroluminescence phenomenon of a solid fluorescent material, and is partially put into practical use as a small display.

  Organic electroluminescent devices can be classified into several groups depending on the material used for the light emitting layer. One typical example is a low molecular weight organic electroluminescent device using a low molecular weight organic compound in the light emitting layer, which is mainly produced by vacuum deposition. The other is a polymer organic electroluminescent device using a polymer compound in the light emitting layer.

  Polymer organic electroluminescent devices can be formed by spin coating, ink-jet, printing, etc. by using a solution in which the material constituting each functional layer is dissolved. It is attracting attention as a technology that can be expected to increase the area.

  A typical polymer organic electroluminescent device is produced by laminating a plurality of functional layers such as a charge injection layer and a light emitting layer between an anode and a cathode. The structure of a typical polymer organic electroluminescent element and the manufacturing procedure thereof will be described below.

  For example, as shown in FIG. 22, first, PEDOT: PSS (mixture of polythiophene and polystyrene sulfonic acid: hereinafter referred to as PEDOT) as the charge injection layer 126 on the glass substrate 100 on which the ITO (indium tin oxide) as the anode 111 is formed. A thin film is formed by spin coating or the like. PEDOT is a material that has become a de facto standard as a charge injection layer, and functions as a hole injection layer by being disposed on the anode side.

  On the PEDOT layer, polyphenylene vinylene (hereinafter referred to as PPV) and a derivative thereof, or polyfluorene and a derivative thereof are formed as a light emitting layer 112 by a spin coating method or the like. Then, a metal electrode 113 as a cathode is formed on these light emitting layers by vacuum deposition to complete the device.

As described above, the polymer organic electroluminescent device has an excellent feature that it can be produced by a simple process, and is expected to be applied to various applications, but it has a sufficiently large emission intensity. This is a problem to be solved in that it cannot be performed and when the driving is performed for a long time, the lifetime is not sufficient.
In particular, when used as an exposure light source in an exposure head, high luminance characteristics are required. On the other hand, when used as a light source for a display device, a long lifetime is required. In the controllability of the pixel region, the pixel area, and the light emission characteristics in the pixel, intensive research has been conducted in order to further improve the controllability.

  The decrease in the emission intensity of polymer organic electroluminescent devices, that is, the deterioration progresses in proportion to the product of the energization time and the current flowing through the device, but the details have not been clarified yet and earnest research is ongoing. It is being done.

  Various speculations have been made about the cause of the decrease in the emission intensity, but the deterioration of PEDOT is considered as one of the main ones. As described above, PEDOT is a mixture of two polymer substances, polystyrene sulfonic acid and polythiophene, the former being ionic and the latter having local polarity in the polymer chain. Due to the Coulomb interaction resulting from such charge anisotropy, the two are loosely coupled, thereby exhibiting excellent charge injection characteristics.

  In order for PEDOT to exhibit excellent properties, close interaction between the two is indispensable. In general, however, a mixture of polymer substances tends to cause phase separation due to a subtle difference in solubility in a solvent. This is no exception for PEDOT (the occurrence of phase separation means that the loose bond between the two polymers is relatively easily removed, and PEDOT is in the organic electroluminescent device). Therefore, components that did not contribute to the coupling, especially ionic components, diffused by the electric field accompanying energization, and are not desirable in other functional layers. In this way, PEDOT has excellent charge injection characteristics, but it cannot be said that it is a stable substance.

Based on the results of various experiments, the present inventors have proposed that it is possible to obtain good injection characteristics by forming molybdenum oxide MoO ₃ instead of PEDOT in response to concerns related to PEDOT as described above. (Patent Document 1).
JP 2005-203340 A

In the above structure, a MoO ₃ film having a thickness of about 20 nm is used, and a functional layer such as a light emitting layer is formed thereon.
Conventionally, since organic semiconductors have low mobility, it has been said that good light emission cannot be obtained in organic electroluminescent elements unless they are made as thin as about 100 nm.
When using such a thin light emitting layer, even if a device is created in a vacuum chamber installed in a clean room, it is easy to become a defect immediately if fine particles are present on the pixel, This is a serious problem that hinders mass production.
In particular, on the light-transmitting electrode made of ITO, there are protrusions of ITO itself, adhering dust, and the like, and this is a major factor that decreases the yield rate.

Furthermore, a resist residue may remain on the surface, which may form a non-light emitting region.
As described above, a non-light emitting region may be formed due to various causes such as a decrease in surface smoothness of the translucent electrode itself and a decrease in surface smoothness caused by an adherent to the translucent electrode. Even if the current density is increased, the light emission intensity cannot be increased. For this reason, there is a limit to the luminance that can be obtained, a higher luminance cannot be obtained, it is extremely difficult to reach a sufficiently satisfactory luminance level, and the lifetime is not sufficient.
Under such circumstances, particularly when used as an exposure light source in an exposure head or the like, high luminance characteristics are required, and intensive research has been conducted in search of further higher luminance.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an organic electroluminescent device that operates stably with uniform light emission characteristics and has excellent life characteristics.

  The organic electroluminescent device of the present invention comprises at least a pair of electrodes and a plurality of functional layers formed between the electrodes, and the functional layers have a light emitting function made of at least one kind of organic semiconductor. And a transition metal oxide layer having a thickness of at least 30 nm or more.

The inventors have already proposed in Patent Document 1 that the injection characteristics better than PEDOT can be obtained by thinly forming MoO ₃ which is one of the transition metal oxides. However, it was said that it was necessary to be 20 nm or less at most. As a result of various experiments in such a situation, the thickness of the transition metal oxide, especially the thickness of MoO ₃ , is very insensitive to device characteristics, and good hole injection characteristics are obtained even when the film thickness is increased. I found that it can be maintained. Therefore, the present inventors have found that when the film thickness of the transition metal oxide is 30 nm or more, the pixel short circuit can be improved. According to this configuration, when a transition metal oxide layer having a film thickness of 30 nm or more is included, a resist remains during patterning of a transparent electrode such as ITO, or particles adhere to the ITO. In addition, after the transition metal oxide layer having a thickness of 30 nm or more is formed, the layer having a light emitting function formed on the upper layer is formed uniformly without causing a film thickness distribution. Therefore, a layer having a uniform light emitting function can be formed without forming a non-light emitting region and without causing a pixel short circuit, and a good emission spectrum can be obtained. In addition, by using a transition metal oxide having a small specific resistance such as MoO ₃ , an electric field can be applied to a layer having a light emitting function without causing a large voltage drop even when the film thickness is increased. Here, as the transition metal oxide, molybdenum oxide, vanadium oxide, tungsten oxide, or the like can be applied. However, molybdenum oxide (MO _x ) is not limited to MO _3, and those having different valences are also effective. . Vanadium oxide and tungsten oxide having different valences are also effective. An oxide containing a plurality of elements formed by co-evaporation is also applicable.

The organic electroluminescent element of the present invention is the above organic electroluminescent element, wherein the transition metal oxide layer has a specific resistance along the stacking direction smaller than a specific resistance along the plane direction. What is a film | membrane formed into a film so that it may become.
With this configuration, the crosstalk can be prevented because the specific resistance in the lateral direction, that is, the surface direction is large. Accordingly, even if they are integrally formed without patterning, the crosstalk can be prevented, and thus the manufacture becomes easy. In addition, at least the entire substrate serving as the organic electroluminescent element forming region is covered with the transition metal oxide layer, and a stable and highly reliable structure can be formed. Since the specific resistance along the vertical direction, that is, the lamination direction is small, the voltage drop is reduced. As a result of various experiments, the present inventors have found that characteristics are improved when a transition metal oxide layer is interposed between a layer having a light emitting function and an electrode. The present invention has been made paying attention to this point.

The organic electroluminescent device of the present invention includes the organic electroluminescent device, wherein the transition metal oxide layer has a specific resistance of 100,000 ohm / cm ² or more.
With this configuration, even if the transition metal oxide layer is integrally formed for each pixel without being divided, no crosstalk occurs.

  The organic electroluminescent device of the present invention is the above organic electroluminescent device, wherein at least one of the at least one pair of electrodes is mainly indium tin oxide (ITO) or indium zinc oxide (IZO). ).

In the organic electroluminescent device of the present invention, at least one of the at least one set of electrodes is formed on a light-transmitting substrate surface, and the transition metal oxide is formed on the electrodes. This includes a layer having a light emitting function disposed thereon.
With this configuration, a so-called bottom emission type organic electroluminescent element that emits light from the substrate side can have high luminance and long life. The transition metal oxide layer is preferably a hole injection layer.

  The organic electroluminescent device of the present invention includes a buffer layer between the transition metal oxide layer and the layer having a light emitting function.

  In the organic electroluminescent element of the present invention, the buffer layer is an electron block layer.

  Moreover, the organic electroluminescent element of this invention WHEREIN: The said buffer layer contains a high molecular compound.

Moreover, the organic electroluminescent element of this invention contains the said pixel control layer between the said electrode and the layer which has the said light emission function, and what prescribed | regulated the light emission area | region.
With this configuration, the step of the pixel regulation layer is relaxed by the sufficiently thick transition metal oxide layer, and the thickness of the layer having a light emitting function formed on the upper layer can be made more uniform. Further, by increasing the film thickness of the transition metal oxide layer to 30 nm or more as in the present invention, the light emission profile is improved. However, when the transition metal oxide layer is formed thick, it is necessary to use a material that does not have a large specific resistance, such as MoO ₃ .

Moreover, the organic electroluminescent element of this invention contains what the said pixel control layer is an insulating film.
As the pixel regulation layer, there are a method using a light shielding film and a method using an insulating film. By using an insulating film, pixel short-circuiting can be prevented.

  The organic electroluminescent element of the present invention includes one in which the pixel restricting layer is a silicon oxide film.

  Moreover, the organic electroluminescent element of this invention contains the said pixel control layer is a silicon nitride film.

Moreover, the organic electroluminescent element of this invention contains the said pixel control layer comprised with the photoresist material.
By using a photoresist material, a pixel regulation layer having a desired thickness can be easily formed using photolithography.

In addition, the organic electroluminescent device of the present invention includes a device in which the entire surface of the pixel regulating layer is covered with a transition metal oxide layer, and a layer having a light emitting function is formed thereon.
With this configuration, the transition metal oxide layer is formed on the pixel regulation layer and covers from the light emitting region to the pixel regulation layer, so that the layer having a light emitting function is formed on a smoother surface. Thus, a uniform film thickness distribution can be obtained, and a longer life can be achieved.

In the organic electroluminescent element of the present invention, the transition metal oxide layer is formed below the pixel regulating layer, and the transition metal oxide layer is in contact with the functional layer only in a light emitting region. including.
With this configuration, the background of the pixel regulation layer can be smoothed, and even if the thickness of the pixel regulation layer is reduced by that amount, sufficient insulation or light shielding can be maintained. As a result, it is possible to reduce the level difference caused by the above, and to make the film thickness distribution of the layer having a light emitting function more uniform.

The organic electroluminescent device of the present invention, the transition metal oxide layer including those which molybdenum oxide (MoO _x layer such as MoO ₃ layer).
With this configuration, the surface can be flattened and smoothed without increasing the specific resistance in the vertical direction.

The organic electroluminescent device of the present invention, the thickness of the MoO ₃ layer include those at 40nm or more.
With this configuration, in the case of a transition metal oxide layer such as a MoO ₃ layer, since the specific resistance in the vertical direction is sufficiently small, the occurrence of a short circuit can be suppressed even when the thickness is 40 nm.

Furthermore, the organic electroluminescent element of this invention contains the film thickness of the said pixel control layer being 20 nm or more and 100 nm or less.
With this configuration, by forming a thick transition metal oxide layer, the base surface when forming the light emitting layer can be more flattened and smoothed when the pixel regulating layer is in the upper layer or lower layer. Since it can measure, the film thickness of the pixel regulating layer can be selected from a wide range in consideration of other factors.

  Moreover, the organic electroluminescent element of this invention contains the layer in which the said light emission function contains at least 1 sort (s) of polymer light-emitting material.

  Moreover, the organic electroluminescent element of this invention contains the layer in which the said layer with the light emission function contains the high molecular compound containing a fluorene ring.

In the organic electroluminescent device of the present invention, the layer having the light emitting function includes polyfluorene represented by the following general formula (I) and derivatives thereof (R1 and R2 each represent a substituent). It is characterized by.

  Moreover, the organic electroluminescent element of this invention contains the layer in which the said light emission function contains a phenylene vinylene group.

In the organic electroluminescent device of the present invention, the layer having the light emitting function includes polyphenylene vinylene represented by the following general formula (II) and derivatives thereof (R3 and R4 each represent a substituent). It is characterized by.

In the organic electroluminescent device of the present invention, the functional layer is formed by sequentially laminating a charge injection layer disposed on the hole injection side, a buffer layer, and a layer having a light emitting function. including.
Here, it is desirable to interpose a layer having a function such as a charge blocking layer as the buffer layer. The MoO ₃ layer also functions as a hole injection layer.

  The organic electroluminescent device of the present invention includes a layer having a light emitting function made of at least one kind of polymer substance having a tree-like multi-branched structure and a charge injection layer made of at least one kind of inorganic substance. .

  In the organic electroluminescent device of the present invention, the layer having the light emitting function is composed of a dendritic multi-branched polymer structure mainly having a light emitting structural unit.

  In the organic electroluminescent device of the present invention, the layer having the light emitting function is composed of a dendritic multi-branched low molecular structure having a light emitting structural unit as a center.

In the organic electroluminescent device of the present invention, an anode which is one of the pair of electrodes is formed on a light-transmitting substrate, and the transition metal oxide formed on the anode A layer of MoO ₃ as a layer, a hole injection layer, a layer having the light emitting function, an electron injection layer formed on the layer having the light emitting function so as to face the hole injection layer, It includes one in which the cathode which is the other electrode of the set of electrodes disposed on the electron injection layer is sequentially laminated.

  In the present invention, the organic electroluminescent elements are two-dimensionally arranged to constitute a display device.

  In the present invention, the organic electroluminescent elements are arranged in a line to form a light emitting unit, thereby forming an exposure apparatus.

In the present invention, a step of forming a transition metal oxide layer having a thickness of 30 nm or more on the surface of the substrate on which one electrode of a set of electrodes is formed, and a step of forming a layer having a light emitting function thereon It is characterized by including.
With this configuration, the transition metal oxide layer is formed with a large film thickness, so that when the layer having the light emitting function is formed, the surface can be flattened and smoothed, and the film thickness can be formed uniformly. Can do.

According to the present invention, the method for manufacturing an organic electroluminescent element includes a step of forming a pixel regulating layer prior to the formation of the transition metal oxide layer, and has a light emitting function on the transition metal oxide layer. And a step of forming the layer.
With this configuration, a step having a light emitting function is formed on the surface flattened by the transition metal oxide layer, resulting in a light emitting function having a more uniform film thickness distribution. The possessed layer can be formed.

According to the present invention, in the method for manufacturing an organic electroluminescent element, the method includes a step of forming a pixel regulation layer after the formation of the transition metal oxide layer, and a layer having a light emitting function is formed on the pixel regulation layer. And a step of forming.
With this configuration, the pixel regulation layer is formed on the surface more flattened by the transition metal oxide layer, and a layer having a light emitting function with a more uniform film thickness distribution can be formed.

Here, the functional layer may include a layer having a light emitting function made of at least one kind of polymer substance, at least one kind of buffer layer, and a charge injection layer made of at least one kind of inorganic substance.
According to this configuration, by using an inorganic substance as the charge injection layer, it is possible to obtain an organic electroluminescent element having extremely large emission intensity and stable characteristics. It is possible to maintain stable characteristics without becoming unstable even when the current density is increased, such as PEDOT in which loose coupling due to Coulomb interaction between two kinds of polymer materials is easily released. This is probably because the emission intensity can be increased. In addition, by using at least one type of buffer layer, for example, it is possible to prevent electrons from escaping to the anode, and it is possible to prevent current from flowing without contributing to light emission. By providing the charge injection layer made of at least one inorganic material in this way, the light emission intensity and light emission efficiency of the device can be maintained at a high level over a wide range of current densities, and the lifetime is also improved. Therefore, it is possible to realize an organic electroluminescent device that operates stably over a wide luminance range up to high luminance and has excellent life characteristics. Here, the light emitting layer is preferably a conjugated polymer.

  Moreover, the organic electroluminescent element of this invention contains the layer in which the said layer with the light emission function contains the high molecular compound containing a fluorene ring. Here, the polymer compound containing a fluorene ring refers to a compound in which a desired group is bonded to the fluorene ring to form a polymer. Although high molecular compounds having various groups bonded thereto are commercially available, the details are not described here because many details are not known.

  Note that the layer having a light emitting function is not limited to a layer having only a light emitting function, but includes a layer having another function such as a charge transport function. In the following embodiments, the light emitting layer is simplified.

  According to the organic electroluminescent device of the present invention, there is no occurrence of leakage, it operates stably and has excellent life characteristics, so that a strong electric field, large current, high It is possible to realize stable charge injection and maintenance of luminous efficiency up to driving conditions such as an exposure apparatus that requires severe conditions of luminance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view illustrating a configuration of an organic electroluminescent element used in an optical head provided in an exposure unit of an image forming apparatus according to Embodiment 1 of the present invention. This electroluminescent element includes an anode made of an ITO layer as a first electrode 111, a cathode as a second electrode 113, and a functional layer formed between these electrodes on a light-transmitting glass substrate 100. The functional layer includes a layer having a light emitting function consisting of an organic semiconductor polymer layer, that is, a light emitting layer 112, and a MoO film having a thickness of 40 nm as a transition metal oxide layer 115 between the electrode and the light emitting layer 112. ₃ layers, and a pixel restricting layer 114 made of a silicon nitride film with a thickness of 50 nm on the upper layer, and a thickness of the MoO ₃ layer as the transition metal oxide layer 115 that could not be considered in the past characterized by a thickness 40 nm, on which to flatten and smooth the surface by MoO ₃ layer of thick film, it was configured to restrict the area of good light-emitting region is To. Further, when a transition metal oxide such as MoO ₃ is formed, the transition metal oxide layer 115 is formed by a vacuum evaporation method. At the time of film formation, the composition ratio of the evaporation source, the pressure in the chamber, The film is formed so that the specific resistance is 10 MΩcm or more by controlling the temperature. Under the current film formation conditions, when 99.999% MoO ₃ is used as the evaporation source, the specific resistance becomes 10 MΩcm or more. This is presumably because the crystal structure changed according to the film formation conditions during the film formation, and as a result, the specific resistance became 10 MΩcm or more.
Further, the specific resistance in the stacking direction can be set to about one third of the specific resistance in the plane direction by adjusting the film forming conditions. This is considered to be due to the occurrence of a crystalline anisotropic structure during film formation, resulting in a difference between the specific resistance in the stacking direction and the specific resistance in the plane direction. Although it is not clearly understood, by selecting the conditions such as the purity of the evaporation source in this way, it is possible to obtain a transition metal oxide whose specific resistance in the stacking direction is about one third of the specific resistance in the plane direction. it can.

Here, an electron blocking layer 116 made of TFB is formed between the thick MoO ₃ layer serving as the transition metal oxide layer 115 and the first electrode 111 serving as the anode. The second electrode, that is, the cathode 113 is composed of a barium electrode 113a having a film thickness of about 3 nm and an aluminum electrode 113b having a film thickness of 150 nm formed thereon.

  According to this configuration, the background of the pixel regulation layer can be smoothed, and even if the thickness of the pixel regulation layer is reduced by that amount, sufficient insulation can be maintained. As a result of the reduction in the level difference caused, it is possible to make the film thickness distribution of the layer having the light emitting function more uniform. Also, there was no short circuit of the pixels. The result of measuring the light emission characteristics at this time is shown in FIG. Here, the horizontal axis represents position, and the vertical axis represents emission intensity. As is apparent from this figure, it has a rectangular emission spectrum and shows good emission characteristics. Here, the pixel regulation layer may be a light shielding material instead of an insulating material. Moreover, even if it has both the light-shielding property and the insulating property, the light emission region can be well regulated, and the pixels can be defined.

By the way, the specific resistance can be changed by controlling the impurities and oxygen defects contained in the used transition metal oxide. For example, when depositing MoO ₃ by vacuum deposition, it can be changed depending on the purity of the MoO ₃ powder used as the evaporation source. For example, when 99.999% MoO ₃ is used as the evaporation source, the specific resistance is 10 MΩcm or more, but when 99.9% MoO ₃ is used, the specific resistance is 1 MΩcm.
When the film is formed by sputtering, the purity similarly affects the MoO ₃ target material, and the higher the purity, the higher the resistance value. In the case of sputtering, Mo metal is used as a target agent, and changes greatly depending on whether the coexisting gas is oxygen or nitrogen. In addition, changing each partial pressure changes the oxygen defects and ionization potential of the film, and the specific resistance can also be controlled. The above method is not limited to MoO ₃ , and the same applies when other elements such as tungsten or vanadium are used.
The specific resistance is preferably 1 MΩ to 100 MΩ. If it is less than 1 MΩ, it is difficult to prevent crosstalk, while if it exceeds 100 MΩ, it is difficult to satisfy both conditions for preventing voltage drop.

(Experiment by spin coating)
Next, in this organic electroluminescent element, a sample was prepared by changing the film thickness in order to observe the characteristic change due to the film thickness of the MoO ₃ layer. Here, the light emitting layer 112 was formed by spin coating.
For each sample, an ITO film is formed on the surface of the light-transmitting glass substrate 100 by a sputtering method, the first electrode 111 is formed, and then the MoO ₃ layer 115 is formed to have a desired film thickness by a vacuum deposition method. A film is formed, a silicon nitride film is formed by a CVD method using high-density plasma, and an opening is formed by photolithography to form a pixel regulation layer 114. Then, after the electron blocking layer 116 is formed and patterned, the light emitting layer 112 is formed. As the light emitting layer, a polymer layer is formed by spin coating, and materials will be described later.

As described above, the thickness of MoO ₃ was changed to create 100 elements (pixels), and the lifetime of 100 elements was measured under a constant luminance of 10000 cd / m ² to evaluate the variation in the lifetime.
The lifetime in this case was defined as the elapsed time until the current value input to the element reached four times the initial value.

As a result, as shown in FIG. 22, the sample R101 using PEDOT125 on the first electrode 111 had an average life of 11 hours, a minimum value of 0.5 hours, and a maximum value of 18 hours. For samples R106 and R110, the average lifetime was 9 hours and 6 hours, respectively, and the minimum and maximum values showed the same variation as sample R101.
On the other hand, the sample D102 using MoO ₃ as the transition metal oxide layer 115 as the underlayer had an average life of 110 hours and the variation was in the range of 90 to 120 hours. Similar results were obtained for other samples D103-105.

  Further, the number of shorted elements in the pixel corresponding to each of 100 elements was examined. Whether or not it was short-circuited was defined as short-circuiting an element in which no light was emitted within 10 minutes during the life evaluation and a large current flowed.

The number of shorted pixels for sample R101-D115 was measured and recorded in the table.
It is obvious that the element using MoO3 has fewer shorts than the sample using PEDOT, and the number of shorts decreases as the film thickness increases. Further, it can be seen that the element of the conventional example shown in FIG. 22 easily short-circuits when the thickness of the pixel regulation layer is increased, whereas the element using MoO ₃ shows a good result.

(Embodiment 2)
FIG. 3 is a schematic cross-sectional view showing the configuration of the organic electroluminescent element of the optical head provided in the exposure unit of the image forming apparatus according to Embodiment 2 of the present invention. This electroluminescent element is the same as that of the above-described embodiment in that the entire surface of the pixel regulating layer 114 is covered with a MoO ₃ layer as a transition metal oxide layer 115, and a layer 112 having a light emitting function is formed thereon. Different from Form 1. Others are formed in the same manner as in the above embodiment.

According to this configuration, since the MoO ₃ layer (115) is formed on the pixel regulation layer 114 and covers from the region serving as the light emission region to the pixel regulation layer 114, the layer having a light emitting function is It is formed on a smoother surface, a uniform film thickness distribution can be obtained, and a longer life can be achieved.

  The results of measuring the light emission characteristics at this time are shown in FIG. Here, the horizontal axis represents position, and the vertical axis represents emission intensity. As is apparent from this figure, it has a rectangular emission spectrum and shows good emission characteristics. Compared with the first embodiment shown in FIG. 2, the emission spectrum is slightly steeper.

Next, an experiment for confirming the effect of the present invention was performed by changing the film thickness of MoO ₃ in this structure. In this embodiment, an inkjet method is used.
First, a polyimide film is formed on a glass substrate or ITO substrate made of an ITO thin film on which the first electrode 111 is formed, a photolithography process is performed using a resist, and a pixel regulation layer (bank) having a side of 35 μm is pitched. 10 dots were produced at 42 μm. The polyimide bank thickness was 2 μm.

  After applying PEDOT to a thickness of about 70 nm by the ink jet method on the first electrode 111 made of the ITO thin film provided with the pixel regulating layer 114 thus obtained and baking it, the electronic block layer Was applied and baked by an ink jet method. Subsequently, the polymer type red light emitting material was applied and baked by the same ink jet method. Further, a cathode made of Ba and Al was vapor-deposited to a total of 120 nm by a resistance heating vapor deposition device so as to be common to all dots, and an organic electroluminescent device as shown in FIG. 22 was formed as a comparative example. R201.

Next, using the same substrate, instead of the PEDOT layer 125, MoO ₃ was vacuum-deposited by changing the thickness to 20 nm, 40 nm, 80 nm, and 120 nm, and the electron blocking layer 116 was similarly formed thereon using inkjet. A light emitting layer 112 and a cathode 113 were provided, and Samples D202 to 205 were obtained.
A DC voltage was applied to the obtained sample, and the light emission distribution within one pixel was measured using a high-resolution CCD camera.

As a result, in the sample R201, a bell-shaped light emission profile was obtained as shown in FIG. 23, whereas in the sample using MoO ₃ as shown in FIG. 6, a light emission profile close to a rectangle was obtained. .

The light emission profile of PEDOT became bell-shaped because the PEDOT layer, the electron blocking layer, and the light emitting layer had uneven thickness in the pixels, resulting in a change in light emission efficiency and a change in the light emission profile. Seem. On the other hand, it is considered that the uniformity of film thickness is improved because the light emission profile of the pixel using MoO ₃ is rectangular.

Next, these were adjusted to have an initial luminance of 12000 cd / m ² and subjected to a life test. As a result, the sample 201 was halved in 30 minutes, whereas the sample using MoO ₃ showed a maximum half-life of 100 hr and the thickness dependency was small.

This indicates that when MoO ₃ is used for the electron block layer, the difference from PEDOT is further increased when the ink jet method is used. PEDOT is a water-dispersed solution, and the surface is hydrophilic even after drying, whereas the ITO surface is hydrophilic and the bank material has an oleophilic surface such as polyimide. As a result, when PEDOT is manufactured by the inkjet method, it is considered that the portion where the droplet contacts the bank is repelled and thinned.

  Furthermore, when an electron block layer and a light emitting layer dissolved in an organic solvent (for example, xylene, toluene, etc.) are ejected from an inkjet nozzle on the upper part of the PEDOT layer, it is difficult to spread on the PEDOT, and the portion in contact with the bank spreads. Therefore, these layers are not uniform. On the other hand, since the surface of the MoO3 layer is not as hydrophilic as the PEDOT layer, it can be confirmed that the organic layer dissolved in the organic solvent spreads even if the ink jet method is used, and at least one of the layers is surrounded by the bank. It turns out that it is very effective in making a film thickness uniform.

On the other hand, as a result of the obtained life evaluation, the maximum value of the life was about 100 hr. However, when MoO ₃ was thin, many short-circuited elements were seen in the middle of the life, whereas 40 nm, 80 nm, and 120 nm. There was no short-circuited element having a thickness of.

The reason for this is that when the MoO ₃ is thin, there are irregularities due to microcrystals on the ITO surface, the influence of dust on the process, etc., whereas when the thick film MoO ₃ of the present invention is used, the surface that may cause a short circuit It is presumed that the protrusions and dust are covered with MoO ₃ so that the light emission characteristics do not change. However, the real factor is still unknown. However, from the experimental facts, it was confirmed that the sample using the thick MoO ₃ had high reliability.

(Embodiment 3)
FIG. 5 is a cross-sectional view showing the configuration of the optical head provided in the exposure section of the image forming apparatus according to Embodiment 3 of the present invention, showing the electroluminescent element 110 as a light source and its periphery, The relationship of the upper and lower arrangement of each layer constituting the detection element 120 is shown. FIG. 6 is a top view of the main part. This electroluminescent element is a layer having a light emitting function, that is, a light emitting layer composed of an anode as the first electrode 111, a cathode as the second electrode 113, and at least one organic semiconductor formed between these electrodes. And a pixel made of a 40 nm-thick MoO 3 layer 115 as a transition metal oxide layer 115 between the electrode and the layer having a light emitting function, and a silicon nitride film having a thickness of 50 nm as an upper layer. which was equipped with a regulating layer 114, by the thickness of the film thickness 40nm of the film thickness of the MoO ₃ layer was not considered in the conventional as transition metal oxide layer 115, the MoO ₃ layer of the thick film It is characterized in that the surface of the light emitting region is well regulated after the surface is flattened and smoothed.

  Here, the silicon nitride film as the pixel regulation layer 114 is formed to a thickness of about 50 nm by a low temperature CVD method using high density plasma. Then, a resist pattern is formed by photolithography, and etching for forming an opening is performed. After anisotropic etching is performed first, isotropic etching is performed to form a smooth edge pattern. At this time, the angle between the pattern edge and the ground is set to about 3 to 10 degrees.

  In this optical head, as shown in FIG. 6, an electroluminescent element 110 is laminated on an upper layer of a thin film transistor (TFT) constituting a light detecting element 120 formed on a substrate. Since the anode as the first electrode 111 located on the light detection element 120 side is formed so as to cover the entire photoelectric conversion portion of the light detection element 120, the first electrode of the electroluminescent element is the light detection element. It faces the whole photoelectric conversion part. With this configuration, the first electrode effectively acts as the gate electrode of the light detection element, and the channel characteristic of the light detection element is reliably controlled by the potential of the first electrode, which is a stable potential, and stable light emission characteristics. It is possible to provide an optical head having Further, a cathode as the second electrode 113 provided so as to face the first electrode with the light emitting layer interposed therebetween is formed on the upper layer side.

Further, this optical head, the outer edge of the island region 121 of the polycrystalline silicon constituting the element region of the photodetector element 120 is formed such that the outside of the light emission region A _LE of the electroluminescent element. Thus, here namely the island region 121 of the light detecting element 120 result in the formation of the step, formed to the outer edge of the element region A _R is the outside of the light emission region A _LE of the electroluminescent element, There is no step in the region corresponding to the light emitting region of the electroluminescent element, and the base of the light emitting layer forms a flat surface. Therefore, in the light emitting region that is the effective region of the optical head, the light emitting layer of the optical head is Uniformly formed.

In FIGS. 10A and 10B, it can be seen that light is emitted in a portion where charge injection should be blocked by the pixel regulation layer (that is, a portion that should not emit light originally). This abnormal light-emitting portion is just above the pixel regulation layer (see FIGS. 9A and 9B and is obvious by comparing FIGS. 10A and 10B). This means that a leak current flows through the pixel regulation layer. In comparison with this, in FIGS. 9A and 9B, the light emitting region completely coincides with the opening provided by the pixel regulating layer.
According to the electroluminescent element of the present embodiment in which the surface of the pixel regulating layer is smoothed, it is possible to form a light emitting state with a large light / dark ratio without leaking light emission.
As already described, the surface average roughness of the pixel regulation layer of the organic electroluminescent element shown in FIGS. 10A and 10B is 5.5 nm, which is the maximum surface of the pixel regulation layer. The sum of absolute values of peak height and maximum valley depth is 20.8 nm of the conventional example. It is difficult to employ an organic electroluminescent element produced under such conditions in a precision instrument such as an exposure apparatus described later.
The individual pixels formed by the exposure apparatus are required to have extremely high uniformity. For this reason, the shape of the light emitting region must be formed constant. If an unstable condition such as a leak occurs, this requirement cannot be satisfied. From this point of view, in an application such as an exposure apparatus, the surface average roughness Ra ≦ 1.0 nm of the pixel regulation layer and the maximum peak height of the pixel regulation layer corresponding to FIGS. 9A and 9B. : Rp and maximum valley depth: Sum of absolute values of Rv ≦ 10 nm accuracy is required.
However, in an application where the accuracy of the shape of each light emitting area is not required, such as a lighting device, even in the light emitting state as shown in FIGS. Must not. In this case, there is a leak in the pixel regulation layer, but the emission luminance in the leak portion is small, does not affect the purpose of use of the application, and leads to destruction of the organic electroluminescent device not. From this point of view, in an application such as a lighting device, the surface average roughness Ra ≦ 5.0 nm of the pixel regulating layer and the maximum peak height of the pixel regulating layer corresponding to FIGS. 9A and 9B: Rp and maximum valley depth: The sum of absolute values of Rv ≦ 20 nm can be sufficiently put into practical use if the accuracy of about 20 nm is satisfied.
An application such as a display device represented by a display is located in the middle. In a display device, reproducibility of halftone (gradation) is important. Strictly speaking, the light emission luminance of each pixel varies depending on the presence or absence of light emission due to the leakage of the pixel regulation layer described above. However, if this variation range is less than one gradation step in the reproducible luminance range (that is, dynamic range) of the display device, there is no particular problem. In a normal display device, the number of gradation steps is set to about 64. From this point of view, in an application such as a display device, for example, the surface average roughness Ra ≦ 2.0 nm of the pixel regulation layer, the maximum peak height of the pixel regulation layer: Rp, which is intermediate between the above-described exposure apparatus and illumination equipment. Maximum valley depth: If the accuracy of the sum of absolute values of Rv ≦ 15 nm is satisfied, it can be sufficiently put into practical use.

In order to bring the pixel regulating layer into a desired surface state, in the plasma CVD apparatus for forming a silicon nitride film, for example, film formation is performed at a low temperature, the input power is set low, and the film formation rate is reduced. This can be realized by adjusting the film formation conditions such as changing the mixing ratio of SiH ₄ and NH ₃ which is the introduced gas during film formation, specifically, increasing the ratio of SiH ₄ . It can also be easily realized by adjusting the surface roughness by forming a pixel regulating layer and performing surface treatment such as plasma treatment after patterning or simultaneously with patterning. In addition, the film forming conditions are not limited to the above, because each apparatus has various film forming characteristics, and the film forming speed is increased at a high temperature to form a smoother surface state. . Further, the film can be smoothed by plasma treatment after film formation. Furthermore, when an inorganic oxide layer such as molybdenum oxide is formed between the anode and the pixel regulation layer, the surface treatment is smooth without causing deterioration of the surface even when the plasma treatment is performed. Therefore, the end surface of the pixel regulating layer is also smoothed together with the surface of the inorganic oxide layer. On the other hand, when the lower layer of the pixel regulation layer is a polymer layer, the plasma treatment may cause deterioration.

  In the above embodiment, a method of interposing an insulating film such as a silicon nitride film as an insulating layer having an opening as the pixel regulating layer is used. However, a light-shielding metal film such as tungsten or a lamination with a light-shielding film is used. It may be composed of a body. When a light-shielding metal film is used, the light emitting area is optically defined without changing the light emitting area.

  In addition, in order to make a pixel control layer into a desired surface state, it is realizable by adjusting film-forming conditions, such as forming into a film at low temperature. It can also be easily realized by adjusting the surface roughness by forming a pixel regulating layer and performing surface treatment such as plasma treatment after patterning or simultaneously with patterning.

As shown in FIG. 5, the optical head using the organic electroluminescent element of the present embodiment has a light detecting element 120 on a glass substrate 100 on which a base coat layer 101 for planarization is formed. A thin film transistor as a switching transistor 130 for sequentially laminating the electroluminescent element 110 and driving the electroluminescent element while correcting the driving current or the driving time according to the output of the photodetecting element 120 A drive circuit (140) as a chip IC connected to the thin film transistor is mounted. The photodetector element 120 is the source region 121S by doping the desired concentration at a channel region formed of the island region A _R of polycrystalline silicon layer formed on the base coat layer 101 surface of a strip-shaped i layer, a drain A source made of a polycrystalline silicon layer formed through a through hole so as to penetrate the first insulating film 122 and the second insulating film 123 made of a silicon oxide film formed in the region 121D. And drain electrodes 125S and 125D. Further, an electroluminescent element 110 is formed on the upper layer through a silicon nitride film as a protective layer 124, and ITO (indium tin oxide) 111 serving as an anode, a protective film 124, a light emitting layer 112, a cathode Each layer is formed in the order of 113.

On the other hand, each layer constituting the photodetecting element 120 is formed in the same manufacturing process as the selection transistor 130 as a driving transistor. In other words, the source regions 132S and 132D are formed in the same process as the semiconductor island of the photodetecting element across the channel region 131C, the source / drain electrodes 134S and 134D that are in contact therewith are stacked, and the gate electrode 133 and the selection transistor The thin film transistor is configured.
Each of these layers is formed through a usual semiconductor process such as formation of a semiconductor thin film by a CVD method, patterning by photolithography, impurity ion implantation, and formation of an insulating film.

  Here, the glass substrate 100 is a single plate of colorless and transparent glass. Examples of the glass substrate 100 include transparent or translucent soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz glass, and other transition metal oxide glasses, inorganic fluoride. Inorganic glass such as compound glass can be used.

Other materials can be used as the glass substrate 100, for example, transparent or translucent polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyether sulfone, polyvinyl fluoride, polypropylene, polyethylene, polyacrylate, amorphous polyolefin. Polymer films using polymer materials such as fluororesin polysiloxane and polysilane, or transparent or translucent chalcogenoid glasses such as As ₂ S ₃ , As ₄₀ S ₁₀ , S ₄₀ Ge ₁₀ , ZnO, Nb _When extracting light emitted from a material such as metal oxide and nitride, such as ₂ O, Ta ₂ O ₅ , SiO, Si ₃ N ₄ , HfO ₂ , TiO ₂ , or light emitting region without passing through the substrate , Opaque silicon, germanium, silicon carbide, gallium arsenide, A semiconductor material such as gallium phosphide, or the above-mentioned transparent substrate material containing a pigment or the like, a metal material whose surface is subjected to insulation treatment, and the like can be appropriately selected and used, and a laminated substrate in which a plurality of substrate materials are laminated is used. You can also.

  On the surface of the substrate such as the glass substrate 100 or inside the substrate, a circuit composed of a resistor, a capacitor, an inductor, a diode, a transistor and the like for driving the electroluminescent device 110 is integrated as described later. Also good.

  Further, depending on the application, a material that transmits only a specific wavelength, a material that converts light into a specific wavelength having a light-light conversion function, or the like may be used. The substrate is preferably insulative, but is not particularly limited, and may have conductivity depending on a range or use that does not hinder driving of the electroluminescent element 110.

A base coat layer 101 is formed on the glass substrate 100. The base coat layer 101 is composed of, for example, a first layer made of SiN and a second layer made of SiO ₂ . Each layer of SiN and SiO ₂ can be formed by vapor deposition or the like, but is preferably formed by sputtering.

On the base coat layer 101, the selection transistor 130 of the electroluminescent element 110 and the light detection element 120 are formed using a polycrystalline silicon layer formed in the same process. The driving circuit for the electroluminescent element 110 is composed of circuit elements such as a resistor, a capacitor, an inductor, a diode, and a transistor. In consideration of downsizing of the optical head, it is desirable to use a thin film transistor. In the third embodiment, the light detection element 120 is located between the electroluminescent element 110 including the light emitting layer 112 and the glass substrate 100 which is the light output surface as is apparent from FIG. element region _{a R} of the detecting element 110 is larger than the light emission region _{a LE.} Further, since the light emission region A _LE exists inside the light detection element 120, a material that does not transmit light cannot be used for the light detection element 120. Therefore, in order not to disturb the light output from the light emitting layer 112, it is necessary to use a material having transparency for the light detection element 120. As a material of the photodetecting element 120 having transparency, it is desirable to select, for example, polycrystalline silicon.

In Embodiment 3, after a uniform semiconductor layer is formed over the base coat layer 101, the semiconductor layer is etched to form the selection transistor 130 and the photodetecting element 120 from the same layer. . The process of forming the selection transistor 130 and the metal layer of the photodetecting element 120 independent from each other in the form of islands from the same metal layer is advantageous in reducing the number of manufacturing steps and the manufacturing cost. Note in the photodetector element 120, the element region A _R for receiving the light output from the light emission region A _LE is the surface of the polycrystalline silicon or amorphous silicon that is configured in an island shape having a light-detecting element 120.

On the selection transistor 130 and the light detection element 120 for applying an electric field to the light emitting layer 112 of the electroluminescent element 110, the first insulating layer 122 and the second insulating layer 123 made of this silicon oxide film are protected. The layer 124 acts as a gate insulating film between the layer 111 and the ITO 111 serving as the anode of the electroluminescent element, and the drop width from the ITO potential is determined by the voltage drop due to the film thickness. The first insulating layer 122, the second insulating layer 123, and the protective layer 124 constituting the gate insulating film 3 are made of, for example, SiO _{2 and} are formed by vapor deposition, sputtering, or the like.

  A gate electrode 133 is formed on the surface of the first insulating layer 122 as a gate insulating film directly above the selection transistor 130. For example, Cr is used as the material of the gate electrode 133. The gate electrode 133 is formed by vapor deposition, sputtering, or the like.

  A second insulating layer 123 is formed on the substrate surface on which the gate electrode 133 is formed. The second insulating layer 123 is formed over the entire surface of the stacked body that has been formed so far. The second insulating layer 123 is made of, for example, SiN or the like, and is formed by a vapor deposition method, a sputtering method, or the like.

  On the second insulating layer, a drain electrode 125D as a light detection element output electrode, a source electrode 125S as a light detection element ground electrode, a source electrode 134S, and a drain electrode 134D are formed. The drain electrode 125D as the light detection element output electrode and the source electrode 125S as the light detection element ground electrode are connected to the source / drain regions 121S and 121D of the light detection element 120, and an electric signal output from the light detection element 120. Transmission and grounding of the light detection element 120. The source electrode 134S and the drain electrode 134D are connected to the source / drain regions 132S and 132D of the selection transistor 130, and the gate electrode 133 described above is applied with a predetermined potential difference between the source electrode 134S and the drain electrode 134D. By applying a predetermined potential, the selection transistor 130 has a function as a switching element, and operates as a circuit for driving the electroluminescent element 110 as a light emitting element. For example, a metal such as Cr is used as the material of the drain electrode 125D as the light detection element output electrode, the source electrode 125S as the light detection element ground electrode, the source electrode 134S, and the drain electrode 134D. As shown in FIG. 5, the drain electrode 125 </ b> D as the light detection element output electrode and the light detection element ground electrode pass through the first insulating film 122 and the second insulating layer 123 and are connected to the end of the light detection element 120. Similarly, the source electrode 134S and the drain electrode 134D penetrate the first insulating film 122 and the second insulating layer 123 and are connected to the end portion of the selection transistor 130. Therefore, prior to the formation of the drain electrode 125D as the light detection element output electrode, the source electrode 125S as the light detection element ground electrode, the source electrode 134S, and the drain electrode 134D, the first insulating film 122 and the second insulating layer 123 are formed. On the other hand, the drain electrode 125D as the light detection element output electrode and the source electrode 125S as the light detection element ground electrode and the through hole for connecting the light detection element 120, the source electrode 134S and the drain electrode 134D, and the selection transistor 130 are connected. It is necessary to provide a through hole for this purpose.

  The through holes are formed on the surface of the photodetecting element 120 and the surface of the selection transistor 130, that is, the contact surface between the photodetecting element 120 and the drain electrode 125D serving as the photodetecting element output electrode and the source electrode 125S serving as the photodetecting element ground electrode. 130 and has a depth until the contact surface of the source electrode 134S and the drain electrode 134D is exposed, and is provided by etching or the like directly above the ends of the photodetecting element 120 and the selection transistor 130. For the etching, a halogen-based etching gas is used. Etching gas is introduced and patterned by photolithography while the surface is covered with a resist pattern having openings. (Through holes are opened in the first insulating film 122 and the second insulating layer 123.) At this time, an etching gas that does not cause a chemical reaction with the materials constituting the light detection element 120 and the selection transistor 130 is selected. To do. Processing to expose the contact surface between the source electrode 125S as the photodetection element output electrode and the source electrode 125S as the photodetection element ground electrode and the photodetection element 120 and the contact surface between the source electrode 134S and the drain electrode 134D and the selection transistor 130 is completed. After that, the drain electrode 125D as the light detection element output electrode, the source electrode 125S as the light detection element ground electrode, the source electrode 134S, and the drain electrode 134D are formed. The source electrode 134S and the drain electrode 134D are formed by forming a metal layer serving as a sensor electrode on the surface of the second insulating layer 123, the surface of the through hole and the both sensor electrodes, the surface of the light detection element 120, and the contact surface of the selection transistor 130. After the uniform formation on the surface, the metal layer is etched using a resist pattern formed by photolithography as a mask, and the uniform metal layer is used as a drain electrode 125D as a light detection element output electrode, and the light detection element grounding. It is obtained by dividing the source electrode 125S, the source electrode 134S, and the drain electrode 134D as electrodes.

  After the drain electrode 125D as the light detection element output electrode, the source electrode 125S as the light detection element ground electrode, the source electrode 134S, and the drain electrode 134D are formed, the protective film 124 is formed. The protective film 124 is made of, for example, SiN and is formed by vapor deposition, sputtering, or the like.

An anode 111 is formed on the protective film 124. The anode 111 is made of, for example, ITO (indium tin oxide). As the constituent material of the anode 111, IZO (zinc-doped indium oxide), ATO (Sb-doped SnO ₂ ), AZO (Al-doped ZnO), ZnO, SnO ₂ , In ₂ O _{3 and the} like are used in addition to ITO. be able to. As shown in FIG. 5, the anode 111 is formed on the surface of the protective film 124 that is directly above the photodetecting element 120. As shown in FIG. 5, the anode 111 penetrates the protective film 124 and is connected to the end of the drain electrode 134D. Therefore, before forming the anode 111, it is necessary to provide a through hole for connecting the anode 111 and the drain electrode 134D to the protective film 124. This through hole has a depth until the surface of the drain electrode 134D, that is, the contact surface between the drain electrode 134D and the anode 111 is exposed, and is provided directly above the end of the drain electrode 134D by etching or the like. It is done. After this etching process is performed, a layer of the anode 111 is formed. The anode 111 can be formed by vapor deposition or the like, but is preferably formed by sputtering. In Embodiment 3, ITO is used as the anode 111.

After the anode 111 is formed, a silicon nitride film 114 as a pixel restricting layer is formed. It is desirable that the silicon nitride film 114 as the pixel regulation layer has a high insulating property, a strong resistance to dielectric breakdown, a good film forming property, and a high patterning property. In the third embodiment, silicon nitride or aluminum nitride is used as a material constituting the silicon nitride film 114 as the pixel restricting layer. A silicon nitride film 114 as a pixel restricting layer is provided between a light emitting layer 112 and an anode 111, which will be described later, and insulates the light emitting layer 112 outside the light emitting region _ALE from the anode 111. The place where light is emitted is regulated. Therefore, the region of the light emitting layer 112 that overlaps the silicon nitride film 114 as the pixel restricting layer is a non-light emitting region, and the region that does not overlap the silicon nitride film 114 as the pixel restricting layer is the light emitting region _ALE . Silicon nitride film as the pixel regulating layer 114 restricts so that the light emission region _{A LE} of the light emitting layer 112 is smaller than the element region _{A R} of the light-detecting element 120, and the light emission region _{A LE} photodetection element 120 configured to be placed inside the element region a _R.

After the silicon nitride film 114 as the pixel regulating layer is formed, the light emitting layer 112 is formed. The light emitting layer 112 is formed of an inorganic light emitting material, or a high molecular weight or low molecular weight organic light emitting material described in detail below. As the inorganic light emitting material for forming the light emitting layer 112, titanium / potassium phosphate, barium / boron oxide, lithium / boron oxide, or the like can be used. The polymer organic light-emitting material constituting the light-emitting layer 112 is preferably a material having fluorescence or phosphorescence characteristics in the visible region and good film forming properties. For example, a polymer such as polyparaphenylene vinylene (PPV) or polyfluorene A light emitting material or the like can be used. In addition to Alq ₃ and Be-benzoquinolinol (BeBq ₂ ), low molecular organic light emitting materials constituting the light emitting layer 112 include 2,5-bis (5,7-di-t-pentyl-2). -Benzoxazolyl) -1,3,4-thiadiazole, 4,4'-bis (5,7-benzyl-2-benzoxazolyl) stilbene, 4,4'-bis [5,7-di- (2-Methyl-2-butyl) -2-benzoxazolyl] stilbene, 2,5-bis (5,7-di-t-benzyl-2-benzoxazolyl) thiophine, 2,5-bis ( [5-α, α-dimethylbenzyl] -2-benzoxazolyl) thiophene, 2,5-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl]- 3,4-diphenylthiophene, 2,5-bis (5-methyl-2 -Benzoxazolyl) thiophene, 4,4'-bis (2-benzoxazolyl) biphenyl, 5-methyl-2- [2- [4- (5-methyl-2-benzoxazolyl) phenyl] Benzoxazoles such as vinyl] benzoxazolyl, 2- [2- (4-chlorophenyl) vinyl] naphtho [1,2-d] oxazole, 2,2 ′-(p-phenylenedivinylene) -bisbenzothiazole Such as benzothiazole, 2- [2- [4- (2-benzimidazolyl) phenyl] vinyl] benzimidazole, 2- [2- (4-carboxyphenyl) vinyl] benzimidazole, etc. Whitening agent, tris (8-quinolinol) aluminum, bis (8-quinolinol) magnesium, bis (benzo [f] -8-quino Nor) zinc, bis (2-methyl-8-quinolinolate) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, 8-quinolinol lithium, tris (5-chloro-8- Quinolinol) gallium, bis (5-chloro-8-quinolinol) calcium, poly [zinc-bis (8-hydroxy-5-quinolinyl) methane] and other 8-hydroxyquinoline metal complexes and dilithium ependridione Metal chelated oxinoid compounds, 1,4-bis (2-methylstyryl) benzene, 1,4- (3-methylstyryl) benzene, 1,4-bis (4-methylstyryl) benzene, distyrylbenzene, 1 , 4-Bis (2-ethylstyryl) benzene, 1,4-bis (3-ethyl) Styryl) benzene, 1,4-bis (2-methylstyryl) 2-methylbenzene and other styrylbenzene compounds, 2,5-bis (4-methylstyryl) pyrazine, 2,5-bis (4-ethylstyryl) ) Pyrazine, 2,5-bis [2- (1-naphthyl) vinyl] pyrazine, 2,5-bis (4-methoxystyryl) pyrazine, 2,5-bis [2- (4-biphenyl) vinyl] pyrazine, Distil pyrazine derivatives such as 2,5-bis [2- (1-pyrenyl) vinyl] pyrazine, naphthalimide derivatives, perylene derivatives, oxadiazole derivatives, aldazine derivatives, cyclopentadiene derivatives, styrylamine Derivatives, coumarin derivatives, aromatic dimethylidin derivatives and the like are used. Furthermore, anthracene, salicylate, pyrene, coronene and the like are also used. Alternatively, a phosphorescent material such as fac-tris (2-phenylpyridine) iridium can be used. The light emitting layer 112 made of a high molecular weight material or a low molecular weight material can be obtained by forming a layer in which a material is dissolved in a solvent such as toluene or xylene by spin coating and volatilizing the solvent in the solution. .

Further, as the light emitting layer, a high molecular substance or a low molecular substance having a tree-like multi-branched structure may be used. A substance having a dendritic multi-branched structure is called a so-called dendrimer and emits phosphorescence of a desired color such as green, red, and blue, and thus is effective as a light emitting layer of the organic electroluminescent device of the present invention.
For example, as a dendrimer which emits green phosphorescence, there is an iridium dendrimer complex as shown in the following formula.
For example, as a dendrimer which emits red phosphorescence, there is an iridium dendrimer complex as shown in the following formula.
For example, as a dendrimer emitting blue phosphorescence, there is an iridium dendrimer complex as shown in the following formula. This dendrimer is a complex composed of a mixture of dendrimer A emitting deep blue light and dendrimer B emitting blue-green light.

  In Embodiment 3, the light-emitting layer 112 is described as a single layer for convenience, but the light-emitting layer 112 is sequentially formed from the anode 111 side with the hole transport layer / electron block layer / the above-described organic light-emitting material layer (both The light-emitting layer 112 may have a two-layer structure of an electron transport layer / organic light-emitting material layer (both not shown) in order from the cathode 113 side, or may be positive in order from the anode 111 side. 2 layer structure of hole transport layer / organic light emitting material layer (both not shown), or hole injection layer / hole transport layer / electron blocking layer / organic light emitting material layer / hole blocking layer / A seven-layer structure (both not shown) such as an electron transport layer / electron injection layer may be used. Alternatively, the light emitting layer 112 may have a single layer structure made of only the organic light emitting material described above. As described above, the light-emitting layer 112 in Embodiment Mode 3 includes a case where the light-emitting layer 112 has a multilayer structure having functional layers such as a hole transport layer, an electron block layer, and an electron transport layer. The same applies to other embodiments described later.

The hole transport layer in the functional layer described above preferably has a high hole mobility, is transparent and has good film formability, and besides TPD, porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Or 1,1-bis {4- (di-P-tolylamino) phenyl} cyclohexane, 4,4 ′, 4 ″ -trimethyltriphenylamine, N, N, N ′, N′-tetrakis ( P-tolyl) -P-phenylenediamine, 1- (N, N-di-P-tolylamino) naphthalene, 4,4′-bis (dimethylamino) -2-2′-dimethyltriphenylmethane, N, N, N ′, N′-tetraphenyl-4,4′-diaminobiphenyl, N, N′-diphenyl-N, N′-di-m-tolyl-4,4′-diaminobiphe Aromatic tertiary amines such as Nyl, N-phenylcarbazole, 4-di-P-tolylaminostilbene, 4- (di-P-tolylamino) -4 ′-[4- (di-P—) Stilbene compounds such as (tolylamino) styryl] stilbene, triazole derivatives, oxazizazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, annealed amine derivatives, amino-substituted chalcones Derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, polysilane aniline copolymers, polymer oligomers, styrylamine compounds, aromatic dimethylidin compounds, Poly-3,4 ethylene glycol Organic materials such as polythiophene derivatives such as xylthiophene (PEDOT), tetradihexylfluorenylbiphenyl (TFB), and poly-3-methylthiophene (PMeT) are used. Further, a polymer-dispersed hole transport layer in which an organic material for a low-molecular hole transport layer is dispersed in a polymer such as polycarbonate is also used. There is also a _{MoO 3, V 2 O 5,} WO 3, TiO 2, SiO, also be used transition metal oxides such as MgO. These hole transport materials can also be used as an electron block material.

  Examples of the electron transport layer in the functional layer described above include oxadiazole derivatives such as 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7), and anthraquinodimethane derivatives. , Diphenylquinone derivatives, polymer materials composed of silole derivatives, bis (2-methyl-8-quinolinolate)-(para-phenylphenolate) aluminum (BAlq), bathopproin (BCP), and the like are used. Moreover, the material which can comprise these electron carrying layers can also be used as a hole block material.

  After the light emitting layer 112 is formed, the cathode 113 is formed. The cathode 113 can be obtained, for example, by forming a layer of metal such as Al by vapor deposition or the like. As the cathode 113 of the organic electroluminescent element 110, a metal or alloy having a low work function, for example, a metal such as Ag, Al, In, Mg, Ti, a Mg alloy such as Mg-Ag alloy, Mg-In alloy, An Al alloy such as an Al—Li alloy, an Al—Sr alloy, an Al—Ba alloy, or the like is used. Alternatively, a first electrode layer in contact with a metal such as Ba, Ca, Mg, Li, or Cs, or an organic material layer made of a fluoride or oxide of these metals such as LiF or CaO, and Ag formed thereon It is also possible to use a laminated structure of a metal made of a second electrode made of a metal material such as Al, In or the like.

  The optical head using the organic electroluminescent element of Embodiment 3 as shown in FIG. 5 employs a method of outputting light from the selection transistor 130 side of the organic electroluminescent element. The structure of an organic electroluminescent element is called bottom emission. Since the bottom emission structure extracts light from the glass substrate 100 side, the light detection element 120 needs to be made of a highly transparent material, for example, polycrystalline silicon (polysilicon), as described above. The photo-detecting element 120 made of polycrystalline silicon has a problem that the photocurrent generation capability is lower than that made of amorphous silicon, but for example, a capacitor (not shown) is made organic. The problem can be solved by providing a processing circuit that is provided in the vicinity of the electroluminescent element 110 and stores a charge based on the current output from the photodetecting element 120 in a capacitor for a predetermined period of time and then performs voltage conversion. it can. In the case of the bottom emission structure, since the electrode (anode) on the side from which light is extracted can be easily made transparent, there is an advantage that manufacture is simplified.

  FIG. 6 is a configuration plan view showing the configuration in the vicinity of the light detection element of the optical head using the organic electroluminescent element in the third embodiment of the present invention.

As shown in FIG. 6, the optical head using the organic electroluminescent element of Embodiment 3 is configured by arranging a plurality of electroluminescent elements 110 in the main scanning direction (direction of the element row). One light detection element 120 is arranged corresponding to one light emitting region (light emitting region A _LE ). By setting it as such a structure, the light-emission light quantity of each organic electroluminescent element 110 can be measured independently with the photon detection element 120. FIG. That is, it becomes possible to measure the light quantity of the plurality of organic electroluminescent elements 110 at the same time, and the measurement time can be greatly shortened.

In FIG. 6, the light detection element 120, the drain electrode 125 </ b> D as the light detection element output electrode, the source electrode 125 </ b> S as the light detection element ground electrode, the light emission area A _LE , the element area A _R , and the ITO serving as the anode of the light emitting layer 112. (indium tin oxide) 111, interrelationship of the contact hole _{H D} and the drain electrode 134D are shown. The light detection element 120 is connected to a drain electrode 125D as a light detection element output electrode and a source electrode 125S as a light detection element ground electrode. The drain electrode 125D as the light detection element output electrode is an electrode that transmits an electric signal output from the light detection element 120 for light correction to a correction circuit (not shown). A feedback signal generated by the correction circuit is determined based on the electrical signal, and processing necessary for light correction is performed based on the feedback signal. In the third embodiment, the light emission amount of each electroluminescent element 110 is corrected based on this feedback signal, and the current value for driving each electroluminescent element 110 is controlled by a driver circuit (not shown). Yes. As described above, in Embodiment 3, the amount of emitted light is controlled based on the output of the light detection element 120, but so-called PWM control is performed to control the drive time of each electroluminescent element 110 based on the feedback signal. You may comprise as follows.

  The source electrode 125S as the light detection element ground electrode is an electrode for grounding the light detection element 120. ITO (indium tin oxide) 111 which is an anode of the electroluminescent element 110 as a light emitting element is connected to the drain electrode 134D of the selection transistor 130, and the electroluminescent element 110 is connected via the drain electrode 134D. It is controlled by the selection transistor 130.

As shown in FIGS. 5 and 6, the optical head using the organic electroluminescent element according to the third embodiment mainly includes a light detecting element 120 made of polycrystalline silicon (polysilicon) formed in an island shape. arranged in rows in the scanning direction, than the light emission region a _LE at the bottom of each organic electroluminescent light emitting layer 112 where the light emission region a _LE by silicon nitride film 114 serving as the pixel regulating layer in cents element 110 _is limited it can be seen that also arranged a light-detecting element 120 having a large element region a _R. By making the element region A _R (island-like portion of polycrystalline silicon formed in an island shape) of the light detection element 120 larger than the light emission region A _LE, a local change in the layer thickness of the light-emitting layer 112 is suppressed. Thus, the bias of the current flowing through the light emitting layer 112 can be suppressed. Therefore, it is possible to manufacture an optical head that achieves a uniform light emission distribution and improved lifetime.

Furthermore, since the element region A _R of the light-detecting element 120 configured in an island shape to be mounted on the optical head of the third embodiment larger than the light emitting area or the light emission region A _LE, the output light from the light-emitting layer It can be efficiently converted into an electrical signal used for light correction.

  Next, a light amount correction circuit used in the optical head of the present invention will be described. As shown in an equivalent circuit in FIG. 11, the light amount correction circuit is formed by being integrated on the above-described glass substrate 100 so as to be connected to the driving IC 150 including the charge amplifier and the input terminal of the driving IC 150. The correction circuit unit C includes the switching transistor 130, the photodetection element 120, and the capacitor 140 that is connected in parallel to the photodetection element and charges the output current of the photodetection element. Composed. Although not shown in the cross-sectional view of FIG. 5, the capacitor 140 is a conductive film formed in the same process so as to be connected to the source electrode 134S and the drain electrode 134D of the light detection element. It is formed by sandwiching the second insulating films 122 and 123.

Here, the photodetection element is photoelectrically converted in the polycrystalline silicon layer 121i by the light from the electroluminescent element, and the current flowing from the source region to the drain region is taken out as a photocurrent. Is detected. However, as described above, the ITO electrode 111 that is the anode of the electroluminescent element 110 is used as a gate electrode, and an electric field is applied to the polycrystalline silicon layer 121i that is the channel region of the photodetecting element by the potential of the gate electrode. As a result, the drain current _ID flows. Since the drain current _ID is added to the photoelectric conversion current, the photoelectric conversion current output from the drain electrode 125D to the correction circuit unit C (see FIG. 11) as a sensor output is converted into the actual photoelectric conversion current. The current _ID is added. For this reason, there exists a problem that the light quantity detection accuracy falls. The result of measuring the relationship between the gate voltage Vg and the drain current ID is shown by a solid line in FIG. As is apparent from this figure, it is desirable to use the thin film transistor in a region where the drain current is 0, that is, a region where the transistor operation is turned off (OFF region).

Desirably, the thin film transistor can be used in the OFF region by making the gate potential shift in the negative direction as indicated by a broken line in FIG. 12, and the dark current can be almost eliminated.
Further, the channel is controlled by the gate electric field when the entire polycrystalline silicon layer 121i, which is the channel region of the thin film transistor that constitutes the photodetecting element, is completely covered with the ITO electrode that is the anode of the electroluminescent element. It is more effective.
In the present invention, since it is extremely important to detect the output of the light detection element with high accuracy, it is important to detect the thin film transistor constituting the light detection element in the OFF state.
In addition, the state in which the entire polycrystalline silicon layer that becomes the channel region 121i of the thin film transistor that constitutes the photodetecting element is completely covered with the ITO electrode that is the anode of the electroluminescent element controls the channel by the gate electric field. It is more effective.

The output of the photodetecting element is obtained by taking out a current charged in the capacitor 140 for a desired number of lighting times by switching the selection transistor 130 as shown in timing charts of FIGS. Highly accurate light quantity detection is possible. Here, FIG. 13A is a diagram showing the state of charge, FIG. 13B is a diagram showing the operation of the selection transistor, and FIG. 13C is a diagram showing the lighting timing of the electroluminescent element. 13D shows the potential of the capacitor 140, FIG. 13E shows the output voltage of the operational amplifier, FIG. 13F shows the data read operation, and FIG. ) Is a diagram showing a light amount detection signal.
In addition, since it is very important to detect the output of the light detection element with high accuracy, it is important to detect the thin film transistor constituting the light detection element in an OFF state. Therefore, a desired detection accuracy can be obtained by adjusting the gate potential of the light detection element.

First, the selection transistor 130 is turned on, and the capacitor 140 is charged with the initial voltage V _ref (S1: reset step).
When the selection transistor 130 is turned off, the charge charged in the capacitor element 140 is reduced by the photocurrent flowing through the light detection element 120 (S2: lighting step).
In this state, the switch SW of the charge amplifier 150 is turned OFF, and the charge amplifier is in a measurable state (S3: measurement start step).
Then, the selection transistor 130 is turned on, and the charge lost in the capacitor element 140 is supplied from the capacitor element C _ref of the charge amplifier. As a result, the output voltage V _r0 of the operational amplifier of the charge amplifier 150 increases. Also during this period, the photocurrent of the photodetecting element flows and _Vr0 increases (S4: charge transfer step).
Then, the selection transistor 130 is turned off and V _r0 is determined. This voltage is taken in by the AD converter, and the photometric operation is completed (S5: read step).

As a modification of the third embodiment of the present invention, as shown in FIG. 14, a light-shielding film 104 made of a chromium thin film is formed on the back side of the glass substrate, and the second light emission region _ALE1 is defined by this opening. is doing. By forming the second light emitting region _ALE1 smaller than the opening of the silicon nitride film 114 as the pixel defining portion described in the third embodiment, a step portion of the light emitting layer caused by the silicon nitride film 114 is formed. It can be excluded from the light emission region, and the light emitting layer can be made more uniform. Other configurations are the same as those in the third embodiment.

In the above optical head, the anode as the first electrode 111 of the electroluminescent element may be formed so as to have the same width as the channel region 121i.
With this configuration, the gate electric field is applied with high efficiency, and the light emitting layer itself of the electroluminescent element is formed on a flat surface. It can be avoided. At this time, since the light emitting region does not become a light emitting region on the source / drain region, the light emitting region and the light emitting region can be substantially matched, and a fine line light emitting region can be obtained. Therefore, it is possible to avoid crosstalk when the pitch is increased due to miniaturization. Thus, since a small exposure spot (line) can be obtained in the sub-scanning direction, it is effective for multi-value reproduction based on area modulation.
The exposure head and the photoconductor move relative to each other in the sub-scanning direction, and the exposure area changes with this relative movement. Considering only from the aspect of area modulation, it is ideal that the exposure spot shape is a single line having no width in the sub-scanning direction. However, the light emission luminance in this case must be infinite. That is, in this case, since the light emitting area in the sub-scanning direction becomes small, the light emitting area becomes small, and the exposure condition becomes strict in terms of energy, so it is necessary to increase the luminance.

(Embodiment 4)
Next, FIG. 15 of the present invention is a cross-sectional view of an organic electroluminescent element used in an optical head having a top emission structure. In contrast to the bottom emission structure, the top emission structure is a type in which light output from the light emitting layer 112 is output to the cathode side above the light emitting layer 112. In the configuration of FIG. 11, a reflective layer 105 made of metal is provided on the glass substrate 100, and the light output is on the cathode side.

  When this structure is adopted, as shown in the figure, among the light generated in the light emitting layer 112 of the organic electroluminescent element 110, the light (not shown) is emitted by the light emitted in the direction opposite to the light detecting element 120. (See 28Y to 28K in FIG. 17 described later). On the other hand, the light generated in the light emitting layer 112 is also emitted in the direction opposite to the direction used for exposure, that is, the light detection element 120 side, and this light is received by the light detection element 120.

  When the top emission structure is adopted, it is not necessary for the light used for exposure to pass through the photodetecting element 120. Therefore, the photodetecting element 120 does not need to dare to use highly transparent polycrystalline silicon, and has a high photocurrent generation capability. The photodetecting element 120 may be composed of amorphous silicon (amorphous silicon).

  Now, in order to implement the top emission structure, the cathode needs to be made of a transparent metal material, which is technically difficult. Therefore, as shown in FIG. 15, a very thin metal layer (thin film cathode) 113a such as Al or Ag and a transparent electrode 113b such as ITO are laminated and used as a cathode. Since the metal layer 113a is very thin, it is possible to realize a cathode with a light-transmitting property. The top emission structure requires a larger number of manufacturing steps than the bottom emission structure, and thus the manufacturing cost increases. However, an optical head with good light emission efficiency can be configured.

  The configuration and operation of the electroluminescent element 110 and the photodetecting element 120 constituting the optical head have been described above in detail. Although the light emitting element (electroluminescent element) row in the optical head has been described as one row in the third embodiment, it may be constituted in a plurality of rows so as to substantially increase the amount of emitted light.

  Of course, the above-described structures of the electroluminescent element 110 and the light detecting element 120 can be applied two-dimensionally to a display device.

As a modification of the fourth embodiment of the present invention, as shown in FIG. 16, a light-shielding film 106 made of a chromium thin film is formed on the back side of the glass substrate, and the second light emitting area A _LE1 is defined by this opening. is doing. By forming the second light emitting region _ALE1 smaller than the opening of the silicon nitride film 114 as the pixel defining portion described in the third embodiment, a step portion of the light emitting layer caused by the silicon nitride film 114 is formed. It can be excluded from the light emission region, and the light emitting layer can be made more uniform. Other configurations are the same as those in the third embodiment.

(Embodiment 5)
FIG. 17 is a diagram showing a configuration of an image forming apparatus 21 equipped with an optical head using the organic electroluminescent element of the present invention. In FIG. 17, an image forming apparatus 21 has four color development stations, a yellow development station 22Y, a magenta development station 22M, a cyan development station 22C, and a black development station 22K, arranged in a stepwise manner in the vertical direction. Is provided with a paper feed tray 24 in which the recording paper 23 is accommodated, and a recording paper transport serving as a transport path for the recording paper 23 supplied from the paper feed tray 24 at locations corresponding to the developing stations 22Y to 22K. The path 25 is arranged in the vertical direction from the top to the bottom.

  The developing stations 22Y to 22K form yellow, magenta, cyan, and black toner images in order from the upstream side of the recording paper conveyance path 25. The yellow developing station 22Y includes a photoconductor 28Y and a magenta developing station 22M. The photosensitive member 28M and the cyan developing station 22C include the photosensitive member 28C, the black developing station 22K includes the photosensitive member 28K, and each developing station 22Y to 22K includes a series of electrophotographic systems such as a developing sleeve and a charger (not shown). The member which implement | achieves the image development process in is included.

  Further, exposure devices 33Y, 33M, 33C, and 33K for exposing the surfaces of the photoreceptors 28Y to 28K to form electrostatic latent images are disposed below the developing stations 22Y to 22K. The optical head shown in the third embodiment is mounted on the exposure apparatuses 33Y, 33M, 33C, and 33K.

  The developing stations 22Y to 22K are different in the color of the filled developer, but the configuration is the same regardless of the developing color. Therefore, the developing stations are excluded unless particularly necessary to simplify the following description. 22, the photosensitive member 28, and the exposure device 33 will be described without specifying specific colors.

  FIG. 18 is a configuration diagram showing the periphery of the developing station 22 in the image forming apparatus 21 according to the fifth embodiment of the present invention. In FIG. 18, the developing station 22 is filled with a developer 26 which is a mixture of carrier and toner. Reference numerals 27a and 27b denote stirring paddles for stirring the developer 26. The toner in the developer 26 is charged to a predetermined potential by friction with the carrier by the rotation of the stirring paddles 27a and 27b, and the interior of the developing station 22 is also charged. By circulating, the toner and the carrier are sufficiently stirred and mixed. The photoreceptor 28 is rotated in the direction D3 by a driving source (not shown). A charger 29 charges the surface of the photoreceptor 28 to a predetermined potential. 30 is a developing sleeve, and 31 is a thinning blade. The developing sleeve 30 has a mag roll 32 having a plurality of magnetic poles formed therein. The layer thickness of the developer 26 supplied to the surface of the developing sleeve 30 is regulated by the thinning blade 31 and the developing sleeve 30 is rotated in a direction D4 by a driving source (not shown). The developer 26 is supplied to the surface of the developing sleeve 30 by the action, and an electrostatic latent image formed on the photoconductor 28 is developed by an exposure device to be described later, and the developer 26 that has not been transferred to the photoconductor 28 is developed in the developing station. 22 is collected inside.

  Reference numeral 33 denotes the exposure apparatus already described. In the image forming apparatus 21 to which the exposure apparatus 33 equipped with the optical head using the organic electroluminescent element of the third embodiment is applied, the exposure apparatus 33 forms a latent image stably over a long period of time as described above. Therefore, the product life is long and the exposure apparatus 33 equipped with the optical head of Embodiment 3 can always form a high-quality image because an electrostatic latent image of a desired shape can be obtained over a long period of time.

  In the exposure apparatus 33 according to the fourth embodiment, organic electroluminescent elements are linearly arranged at a resolution of 600 dpi (dot / inch), and the photosensitive member 28 charged to a predetermined potential by the charger 29 is used. An electrostatic latent image of maximum A4 size is formed by selectively turning on / off the organic electroluminescent element according to the image data. Only the toner of the developer 26 supplied to the surface of the developing sleeve 30 adheres to the electrostatic latent image portion, and the electrostatic latent image is visualized.

  A transfer roller 36 is provided at a position facing the recording paper conveyance path 25 with respect to the photoreceptor 28, and is rotated in the direction D5 by a driving source (not shown). A predetermined transfer bias is applied to the transfer roller 36, and the toner image formed on the photoconductor 28 is transferred to the recording paper conveyed through the recording paper conveyance path 25.

  Subsequently, returning to FIG.

  As described above, the image forming apparatus 21 according to the fourth embodiment is a tandem color image forming apparatus in which a plurality of developing stations 22Y to 22K are arranged in a stepwise manner in the vertical direction, and is equivalent to a color inkjet printer. It aims at the size of. Since a plurality of units are arranged in the developing stations 22Y to 22K, in order to reduce the size of the image forming apparatus 21, the developing stations 22Y to 22K themselves are reduced in size and are arranged around the developing stations 22Y to 22K. It is necessary to reduce the members involved in the image process and to reduce the arrangement pitch of the developing stations 22Y to 22K as much as possible.

  In consideration of user convenience when installing the image forming apparatus 21 on the desktop in an office or the like, in particular, accessibility to the recording paper 23 at the time of paper feeding or paper ejection, from the bottom surface of the image forming apparatus 21 to the paper feed port 65. The height is preferably 250 mm or less. In order to realize this, it is necessary to suppress the height of the entire developing stations 22Y to 22K to about 100 mm in the entire configuration of the image forming apparatus 21.

  However, the existing LED head, for example, has a thickness of about 15 mm, and if it is disposed between the developing stations 22Y to 22K, it is difficult to achieve the target. According to the examination results of the present inventors, when the thickness of the exposure device 33 is 7 mm or less, the height of the entire development station is 100 mm or less even if the exposure devices 33Y to 33K are arranged in the gaps between the development stations 22Y to 22K. It is possible to suppress.

  A toner bottle 37 stores yellow, magenta, cyan, and black toners. A toner transport pipe (not shown) is provided from the toner bottle 37 to each of the developing stations 22Y to 22K, and supplies toner to each of the developing stations 22Y to 22K.

  A paper feed roller 38 is rotated in the direction D1 by controlling an electromagnetic clutch (not shown), and feeds the recording paper 23 loaded in the paper feeding tray 24 to the recording paper transport path 25.

  A registration paper 39 and a pair of pinch rollers 40 are provided as a nip conveyance means on the inlet side in the recording paper conveyance path 25 positioned between the paper supply roller 38 and the transfer portion of the most upstream yellow developing station 22Y. The registration roller 39 and the pinch roller 40 pair temporarily stop the recording paper 23 conveyed by the paper supply roller 38 and convey it in the direction of the yellow developing station 22Y at a predetermined timing. This temporary stop restricts the leading edge of the recording paper 23 in parallel with the axial direction of the registration roller 39 and pinch roller 40 pair, thereby preventing the recording paper 23 from skewing.

  Reference numeral 41 denotes a recording paper passage detection sensor. The recording paper passage detection sensor 41 is constituted by a reflective sensor (photo reflector), and detects the leading edge and the trailing edge of the recording paper 23 based on the presence or absence of reflected light.

  When the rotation of the registration roller 39 is started (the power transmission is controlled by an electromagnetic clutch (not shown) and the rotation is turned ON / OFF), the recording paper 23 is conveyed along the recording paper conveyance path 25 in the direction of the yellow developing station 22Y. However, starting from the rotation start timing of the registration roller 39, the writing timing of the electrostatic latent images by the exposure devices 33Y to 33K disposed in the vicinity of the developing stations 22Y to 22K is independently controlled.

  A fixing device 43 is provided as a nip conveying means on the outlet side in the recording paper conveyance path 25 located further downstream of the most downstream black developing station 22K. The fixing device 43 includes a heating roller 44 and a pressure roller 45. The heating roller 44 is a multi-layered roller composed of a heating belt, a rubber roller, and a core material (both not shown) in order from the surface. Among them, the heat generating belt is a belt having a three-layer structure, and is composed of a release layer, a silicon rubber layer, and a base material layer (both not shown) from the side closer to the surface. The release layer is made of a fluororesin having a thickness of about 20 to 30 micrometers and imparts release properties to the heating roller 44. The silicon rubber layer is made of silicon rubber having a thickness of about 170 micrometers and gives the pressure roller 45 appropriate elasticity. The base material layer is made of a magnetic material that is an alloy of iron, nickel, chromium, or the like.

  A back core 26 includes an exciting coil. Inside the back core 46, an excitation coil in which a predetermined number of copper wires (not shown) whose surfaces are insulated is bundled in the direction of the rotation axis of the heating roller 44, and at both ends of the heating roller 44, the heating roller It circulates along the circumferential direction of 44. When an alternating current of about 30 kHz is applied to the exciting coil from an exciting circuit (not shown) that is a semi-resonant inverter, a magnetic flux is generated in a magnetic path constituted by the back core 46 and the base layer of the heating roller 44. Due to this magnetic flux, an eddy current is formed in the base material layer of the heat generating belt of the heating roller 44 and the base material layer generates heat. The heat generated in the base material layer is transmitted to the release layer through the silicon rubber layer, and the surface of the heating roller 44 generates heat.

  Reference numeral 47 denotes a temperature sensor for detecting the temperature of the heating roller 44. The temperature sensor 47 is a ceramic semiconductor obtained by sintering at a high temperature using a metal oxide as a main raw material, and it is possible to measure the temperature of a contacted object by applying a change in load resistance according to the temperature. it can. The output of the temperature sensor 47 is input to a control device (not shown). The control device controls the power output to the exciting coil inside the back core 46 based on the output of the temperature sensor 47, and the surface temperature of the heating roller 44 is about 170 °. Control to be C.

  When the recording paper 23 on which the toner image is formed is passed through the nip formed by the heating roller 44 and the pressure roller 45 that are controlled in temperature, the toner image on the recording paper 23 is connected to the heating roller 44. The toner image is fixed on the recording paper 23 by being heated and pressurized by the pressure roller 45.

  A recording paper trailing edge detection sensor 48 monitors the discharge state of the recording paper 23. Reference numeral 52 denotes a toner image detection sensor. The toner image detection sensor 52 is a reflective sensor unit that uses an electroluminescent element (both visible light) as a plurality of light emitting elements having different emission spectra and a single light receiving element (light detecting element). The image density is detected by utilizing the fact that the absorption spectrum differs depending on the image color between the background and the image forming portion. Further, since the toner image detection sensor 52 can detect not only the image density but also the image forming position, in the image forming apparatus 21 according to the third embodiment, two toner image detection sensors 52 are provided in the width direction of the image forming apparatus 21 to perform recording. The image formation timing is controlled based on the detection position of the image displacement amount detection pattern formed on the paper 23.

  53 is a recording paper transport drum. The recording paper transport drum 53 is a metal roller whose surface is covered with rubber having a thickness of about 200 micrometers, and the recording paper 23 after fixing is transported along the recording paper transport drum 53 in the direction D2. At this time, the recording sheet 23 is cooled by the recording sheet conveying drum 53 and is bent and conveyed in the direction opposite to the image forming surface. As a result, curling that occurs when a high density image is formed on the entire surface of the recording paper can be greatly reduced. Thereafter, the recording paper 23 is conveyed in the direction D6 by the kicking roller 55 and discharged to the paper discharge tray 59.

  Reference numeral 54 denotes a face-down paper discharge unit. The face-down paper discharge unit 54 is configured to be rotatable about the support member 56. When the face-down paper discharge unit 54 is opened, the recording paper 23 is discharged in the direction D7. In the closed state, the face-down paper discharge unit 54 is formed with ribs 57 along the transport path on the back surface so as to guide the transport of the recording paper 23 together with the recording paper transport drum 53.

  Reference numeral 58 denotes a drive source, and a stepping motor is employed in the third embodiment. By the drive source 58, peripheral portions of the developing stations 22Y to 22K including the paper feed roller 38, the registration roller 39, the pinch roller 40, the photoconductors (28Y to 28K), and the transfer rollers (36Y to 36K), the fixing device 43, The recording paper transport drum 53 and the kicking roller 55 are driven.

  A controller 61 receives image data from a computer (not shown) via an external network and develops and generates printable image data.

  Reference numeral 62 denotes an engine control unit. The engine control unit 62 controls the hardware and mechanism of the image forming apparatus 21, forms a color image on the recording paper 23 based on the image data transferred from the controller 61, and performs overall control of the image forming apparatus 21. Yes.

  63 is a power supply unit. The power supply unit 63 supplies power of a predetermined voltage to the exposure apparatuses 33Y to 33K, the drive source 58, the controller 61, and the engine control unit 62, and supplies power to the heating roller 44 of the fixing device 43. The power supply unit also includes a so-called high-voltage power supply system such as charging of the surface of the photosensitive member 28, a developing bias applied to the developing sleeve (see reference numeral 30 in FIG. 15), a transfer bias applied to the transfer roller 36, and the like. .

  The power supply unit 63 includes a power supply monitoring unit 64 so that at least the power supply voltage supplied to the engine control unit 62 can be monitored. This monitor signal is detected by the engine control unit 62 to detect a drop in power supply voltage that occurs when the power switch is turned off or a power failure occurs.

  In the above description, the case where the present invention is applied to a color image forming apparatus has been described. However, the present invention can also be applied to a single color image forming apparatus such as black. When applied to a color image forming apparatus, the development colors are not limited to four colors of yellow, magenta, cyan and black.

  Since the image forming apparatus 21 of the present invention is equipped with exposure apparatuses 33Y to 33K having a uniform light emission distribution and excellent durability, the image forming apparatus 21 is excellent in image quality and durability.

(Embodiment 6)
Next, a display device using the organic electroluminescent element of the present invention will be described. In the display device of this embodiment, a light emitting layer is formed by an inkjet method on a transition metal oxide layer having an ionization potential of about 5.6 eV through a TFB (not shown) as a buffer layer. Fig. 20 is an equivalent circuit diagram of the active matrix display device, Fig. 20 is a layout diagram, and Fig. 21 is a top diagram, which constitutes an active matrix display device in which a drive circuit is formed in each pixel. is there.

  As shown in an equivalent circuit diagram in FIG. 19 and a layout explanatory diagram in FIG. 20, the display device 140 includes an organic electroluminescent element (electroluminescent) 110 and a switching transistor 130 that form pixels, and a photodetecting element. A plurality of drive circuits consisting of two current transistors 120 (T1, T2) and a capacitor C are arranged in the vertical and horizontal directions, and the gate of the first TFT (T1) of each drive circuit arranged in the horizontal direction. An electrode is connected to the scanning line 143 to give a scanning signal, and a drain electrode of the first TFT of each driving circuit arranged in the vertical direction is connected to the data line to supply a light emission signal. A driving power source (not shown) is connected to one end of the electroluminescent element (electroluminescent), and one end of the capacitor C is grounded. Reference numeral 143 denotes a scanning line, 144 denotes a signal line, 145 denotes a common power supply line, 147 denotes a scanning line driver, 148 denotes a signal line driver, and 149 denotes a common power supply line driver.

  FIG. 21 is an explanatory top view of this display device. A transition comprising an anode (ITO) 111, a molybdenum oxide layer having an ionization potential of 5.6 eV, etc. on a glass substrate 100 on which a driving thin film transistor (not shown) is formed. A metal oxide layer 115, a charge blocking layer 116, a light emitting layer 112, and a cathode 113 are formed to form an organic electroluminescent element. As a structure, the anode and the charge injection layer are formed separately, the light emitting layer to the pixel regulating layer 114 are formed from the buffer layer, and the cathode is formed in a stripe shape. In this driving thin film transistor, for example, an organic semiconductor layer (polymer layer) is formed on a glass substrate 100, which is covered with a gate insulating film, a gate electrode is formed thereon, and a through electrode formed on the gate insulating film. Source / drain electrodes are formed through holes. Then, a polyimide film or the like is applied thereon to form an insulating layer (flat layer), and an anode (ITO) 111, a molybdenum oxide layer, an electron blocking layer, an organic semiconductor layer such as a light emitting layer, and a cathode 115 are formed thereon. It has the structure which formed and formed the organic electroluminescent element. In FIG. 21, although capacitors and wirings are omitted, they are also formed on the same glass substrate. A plurality of pixels composed of such TFTs and organic electroluminescent elements are formed in a matrix on the same substrate to constitute an active matrix display device.

  At the time of manufacture, as shown in FIG. 20, a light emitting layer is formed by an inkjet method in the opening 153 formed by the pixel regulating layer 114 formed of an insulating layer.

That is, in manufacturing, the pixel regulation layer 114 is formed on the scanning line 143, the signal line 144, the switching TFT 130, the pixel electrode 111, and the like formed on the glass substrate 100, and then an opening is provided.
Then, a transition metal oxide layer is formed on the entire surface by vapor deposition.
Thereafter, TFB is applied as necessary by an inkjet method. This TFB layer may be applied to the entire surface in the same manner as the transition metal oxide layer, or may be applied only to a portion corresponding to the opening.
Then, after a drying process, a polymer organic EL material corresponding to a desired color (any of RGB) is applied to a position corresponding to the opening by an inkjet method.
Finally, a cathode (not shown) is formed in the region where the display pixel 141 is disposed.

  According to this configuration, a display device that can be driven at high speed and has high reliability can be provided.

  Next, an example of a lighting device in which a plurality of electroluminescent elements 1 are two-dimensionally arranged will be described with reference to FIG. With respect to the electroluminescent elements 110 arranged two-dimensionally, for example, a configuration in which all the electroluminescent elements 1 are simultaneously turned on / off can be realized very easily. However, even in such a configuration where the light is turned on / off all at once, at least one electrode (for example, a pixel electrode made of ITO (see the anode 111 in FIG. 1)) is one unit of each electroluminescent element. It is desirable to have a separate structure. This is because even if the display pixel 141 is defective due to some factor, the defect remains in the display pixel 141, so that the manufacturing yield of the entire lighting device can be improved. The lighting device having such a configuration can be applied to a general lighting fixture in a home, for example. In this case, since the lighting device can be configured to be extremely thin, it can be easily installed not only on the ceiling but also on the wall surface.

  In addition, the electroluminescent device 1 arranged in a two-dimensional manner can easily control the light emission pattern by supplying arbitrary data, and the electroluminescent device 1 according to the present invention includes: Since the light emitting region can be configured with a size of, for example, about 40 μm square, an application can be configured in which data is supplied to the lighting device and also used as a panel type display device. Of course, in this case, the display pixel 141 needs to be painted in red, green, and blue depending on the position, but according to the ink jet method, it is possible to increase the number of colors very easily.

  Conventionally, when a lighting device and a display device are compared, the light emission luminance of the lighting device is larger. However, since the electroluminescent device 110 according to the present invention has extremely high light emission luminance, the lighting device and the display device can be used together. In this case, the illumination device and the display device require a mechanism for adjusting the light emission luminance due to the difference in function (that is, the use mode). For this mechanism, for example, the configuration shown in the third embodiment is adopted. This can be realized by controlling the drive current to adjust the light emission luminance of each electroluminescent element 1. That is, when used as a lighting device, all the electroluminescent elements 1 are driven with a larger current, and when used as a display device, the current value is small and controlled according to the gradation (that is, image data). Each electroluminescent element 1 may be driven. In such an application, the power source for functioning as a lighting device and the power source for functioning as a display device may be a single power source. In the case where the number of gradations when using as a display device is large, the power source (not shown) connected to the common power supply line 145 shown in FIGS. 19 and 20 is switched according to the use mode. It is desirable to use a simple configuration. Of course, even in a mode of use as a lighting device, in a mode where brightness control is necessary (that is, a lighting device having a dimming function), it is easily handled by current value control according to the gradation described above. be able to. Moreover, since the electroluminescent element 1 of the present invention can be formed not only on the glass substrate 2 but also on a resin substrate such as PET, it can be applied as various illumination devices.

  Note that the thin film transistor may be an organic transistor. A structure in which an organic electroluminescent element is stacked on a thin film transistor or a structure in which a thin film transistor is stacked on an organic electroluminescent element is also effective.

  In addition, in order to obtain a high-quality electroluminescent display device, an electroluminescent substrate on which an organic electroluminescent element is formed and a TFT substrate on which a TFT, a capacitor, wiring, and the like are formed are electroluminescent. The electrodes on the cent substrate and the electrodes on the TFT substrate may be bonded together using a connection bank.

  In the above description, the organic electroluminescent element is driven by DC, but may be driven by AC voltage, AC current, or pulse wave.

  In addition, although light emitted from the organic electroluminescent element is extracted from the substrate side, it may be extracted from the surface opposite to the substrate (here, the cathode) or from the side surface.

  The film formation of each layer constituting the organic electroluminescent device of the present invention is not limited to the above method, but vacuum deposition method, electron beam deposition method, molecular beam epitaxy method, sputtering method, reactive sputtering. Method, ion plating method, laser ablation method, thermal CVD method, plasma CVD method, MOCVD method and other vacuum methods, or sol-gel method, Langmuir-Blodget method (LB method), layer-by-layer method, spin coating method, inkjet Needless to say, any method may be used as long as it can be appropriately selected from a wet method such as a method, a dip coating method, and a spray method, and can be formed so that the effect of the present invention can be obtained as a result. Absent.

  In the organic electroluminescent device of the present invention, the buffer layer is a material in which the absolute value of the energy value representing the electron affinity of the buffer layer (hereinafter referred to as electron affinity) is smaller than the electron affinity of the layer having the light emitting function. May be used. With this configuration, the loss of charge can be blocked, and the charge can effectively contribute to light emission in the light emitting layer.

In the organic electroluminescent device of the present invention, the charge injection layer may contain an oxide.
As oxides used here, chromium (Cr), tungsten (W), vanadium (V), niobium (Nb), tantalum (Ta), titanium (Ti), zirconium (Zr), hafnium (Hf) , Scandium (Sc), yttrium (Y), thorium (Tr), manganese (Mn), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), nickel (Ni), copper (Cu) , Zinc (Zn), cadmium (Cd), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb) Bismuth (Bi) or oxides of so-called rare earth elements from lanthanum (La) to lutetium (Lu) can be mentioned. Among these, aluminum oxide (AlO), copper oxide (CuO), and silicon oxide (SiO) are particularly effective for extending the life.
For example, since a transition metal compound has a plurality of oxidation numbers, it can take a plurality of potential levels, facilitate charge injection, and reduce driving voltage.

In the organic electroluminescent device of the present invention, the charge injection layer may contain an oxynitride of a transition metal. For example, ruthenium (Ru) oxynitride crystal Ru4Si ₂ O ₇ N _{2 and the} like are extremely heat-resistant (1500 ° C.) and stable, and therefore can be applied as a charge injection layer by forming a thin film. . In this case, the film can be formed by performing a heat treatment after forming the film by a sol-gel method.

In addition, barium sialon (BaSiAlON), calcium sialon (CaSiAlON), cerium sialon (CeSiAlON), lithium sialon (LiSiAlON), magnesium sialon (MgSiAlON), scandium sialon (ScSiAlON), yttrium sialon (YSiAlON), erbium sialon (E) Further, sialons containing elements of group IA, IIA, IIIB such as neodymium sialon (NdSiAlON), or oxynitrides such as multi-element sialon are applicable. These can be formed by CVD, sputtering, or the like. In addition, lanthanum silicon oxynitrate (LaSiON), lanthanum europium silicon oxynitride (LaEuSi ₂ O ₂ N ₃ ), silicon oxynitride (SiON ₃ ), and the like are also applicable. Since these are mostly insulators, it is necessary to reduce the film thickness to about 1 nm to 5 nm. These compounds have a large exciton confinement effect and may be formed on the side where electrons are injected.

In the organic electroluminescent device of the present invention, the charge injection layer may include a composite oxide containing a transition metal. Although the reason is not clear, when the composite oxide containing a transition metal is used for the charge injection layer, the emission intensity can be greatly improved.
In addition, there are a great many types of complex oxides, and many of them have electronically interesting properties. Specific examples include the following compounds, but these are merely examples.

For example, barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ), calcium titanate (CaTiO ₃ ), potassium niobate (KNbO ₃ ), bismuth iron oxide (BiFeO ₃ ),
Lithium niobate (LiNbO _3), sodium vanadate (Na ₃ VO _4), vanadium iron (FeVO _3), titanate vanadium (TiVO _3), chromic acid vanadium (CrVO _3), vanadium, nickel (NiVO _3), magnesium vanadate (MgVO _3), calcium vanadate (CaVO _3), vanadium lanthanum (LaVO _3), molybdate vanadium (VMoO _5), molybdate vanadium (V ₂ MoO _8), lithium vanadate (LiV ₂ O ₅ ), Magnesium silicate (Mg2SiO4), magnesium silicate (MgSiO ₃ ), zirconium titanate (ZrTiO ₄ ), strontium titanate (SrTiO ₃ ), lead magnesium oxide (PbMgO ₃ ), lead niobate (PbNbO ₃ ), barium borate (BaB ₂ O ₄ ), lanthanum chromate (LaCrO ₃ ), lithium titanate (LiTi ₂ O ₄ ), lanthanum cuprate (LaCuO ₄ ), zinc titanate (ZnTiO ₃ ), calcium tungstate (CaWO ₄ ) and the like are possible.

Although any of these can be used to carry out the present invention, barium titanate (BaTiO ₃ ) is preferably used. BaTiO ₃ is a typical dielectric and is a complex oxide with high insulating properties, but it is possible to inject carriers when used in thin films based on the results of various experiments. I understood. BaTiO ₃ and strontium titanate (SrTiO ₃ ) are stable as compounds and have a very large dielectric constant, so that efficient carrier injection can be performed. For film formation, a sputtering method, a sol-gel method, a CVD method, or the like can be selected as appropriate.

  In the organic electroluminescent device of the present invention, the buffer layer may be disposed between a charge injection layer disposed on the hole injection side and a layer having a light emitting function. With this configuration, the escape of electrons can be blocked, and the electrons can effectively contribute to light emission in the layer having a light emitting function.

  In the organic electroluminescent element of the present invention, the buffer layer may be composed of a polymer layer. With this configuration, since the buffer layer can be formed by a coating method, it can be formed without going through a vacuum process.

In the organic electroluminescent device of the present invention, the anode is formed on a translucent substrate, the charge injection layer has a hole injection layer formed on the anode, and the light emitting function. Including an electron injection layer formed on the layer having a light emitting function so as to face the hole injection layer through a layer, and a cathode formed on the electron injection layer Including things. That is, the organic electroluminescent element of the present invention includes an anode formed on a translucent substrate, a hole injection layer formed on the anode, a buffer layer formed on the hole injection layer, You may make it comprise the electron injection layer formed on the layer with the said light emission function so that it may oppose the said hole injection layer through the layer with the said light emission function, and a cathode.
With this configuration, a buffer layer such as an electron blocking layer is formed on the hole injection layer side where electrons are likely to escape, and a layer having a light emitting function is formed on these layers. It is possible to prevent the layer having damage from being damaged during the formation of the hole injection layer.
Here, the cathode is preferably formed as a multilayer structure in which a layer having a low work function such as a calcium (Ca) layer or a barium (Ba) layer for facilitating electron injection is arranged on the light emitting layer side.

  Among the compounds used in the present invention, compounds having different valences are likely to exist, and include compounds in the form of compounds having different valences other than those exemplified.

  The electroluminescent device of the present invention can increase the brightness, operate stably over a wide range of brightness, and has excellent lifetime characteristics. Therefore, the electroluminescent device has a wide range of applications including flat panel displays and display devices, or light. The head and the image forming apparatus can be applied to a copying machine, a printer, a multifunction printer, a facsimile, and the like.

Cross-sectional schematic diagram of organic electroluminescent element 110 according to Embodiment 1 of the present invention The figure which shows the luminescent property of the organic electroluminescent element Cross-sectional schematic diagram of organic electroluminescent element 110 according to Embodiment 2 of the present invention The figure which shows the luminescent property of the organic electroluminescent element Sectional drawing of the electroluminescent element 110 which comprises the optical head of Embodiment 3 of this invention, and its periphery Plane configuration explanatory diagram showing the configuration in the vicinity of the light detection element of the optical head described in the third embodiment of the present invention A photograph showing the surface physical properties of the pixel regulating layer of the electroluminescent element used in the optical head described in the third embodiment of the present invention. A photograph showing the surface properties of the pixel regulating layer of a conventional electroluminescent device A photograph showing a light emission state of an electroluminescent element used in the optical head described in the third embodiment of the present invention. Photo showing the light emission state of the electroluminescent element used in a conventional optical head Equivalent circuit diagram of a light amount detection circuit of an optical head using the organic electroluminescent element according to the third embodiment of the present invention The figure which shows the characteristic of the photon detection element of the optical head using the organic electroluminescent element as described in Embodiment 3 of this invention. The figure which shows the light quantity detection flow of the optical head using the organic electroluminescent element as described in Embodiment 3 of this invention. Sectional drawing which shows the modification of the optical head using the organic electroluminescent element as described in Embodiment 3 of this invention. Sectional drawing at the time of comprising the organic electroluminescent element of Embodiment 4 of this invention with a top emission structure Sectional drawing which shows the modification of the optical head as described in Embodiment 4 of this invention. Configuration diagram of an image forming apparatus 21 using the optical head according to the fifth embodiment of the present invention. Configuration diagram showing the periphery of the developing station 22 in the image forming apparatus 21 according to the fifth embodiment of the present invention. FIG. 7 is an equivalent circuit diagram of the active matrix display device according to the sixth embodiment of the present invention. Layout explanatory diagram of the display device according to the sixth embodiment of the present invention Top view of the display device according to Embodiment 6 of the present invention. Cross-sectional schematic diagram of organic electroluminescent element 110 of a conventional example The figure which shows the luminescent property of the organic electroluminescent element

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Glass substrate 101 Overcoat layer 110 Electroluminescent element 111 Anode 112 Light emitting layer 113 Cathode 114 Pixel control layer 115 Transition metal oxide layer 120 Photodetection element 121 Polycrystalline silicon layer 121S, D Source / drain region 121i Channel region 122 First insulating layer 123 Second insulating layer 124 Protective layer 125S, D source / drain electrode 130 Drive transistor 131 Active layer 132S, D source / drain region 133 Gate electrode 134S, D source / drain electrode 21 Image forming apparatus 22 Development Station 22Y developing station 22M developing station 22C developing station 22K developing station 23 recording paper 24 paper feed tray 25 recording paper transport path 26 developer 27a stirring paddle 27b stirring paddle 28 Photoconductor 28Y Photoconductor 28M Photoconductor 28C Photoconductor 28K Photoconductor 29 Charger 30 Developing sleeve 31 Thinning blade 32 Mag roll 33 Exposure device 33Y Exposure device 33M Exposure device 33C Exposure device 33K Exposure device 36 Transfer roller 37 Toner bottle 38 Supply Paper roller 39 Registration roller 40 Pinch roller 41 Recording paper passage detection sensor 43 Fixing device 44 Heating roller 45 Pressure roller 46 Back core 47 Temperature sensor 48 Recording paper trailing edge detection sensor 52 Toner image detection sensor 53 Recording paper conveyance drum 54 Face down Discharge unit 55 kick-out roller 56 support member 57 rib 58 drive source 59 discharge tray 61 controller 62 engine control unit 63 power supply unit 64 power supply monitoring unit 65 paper feed port

Claims (31)

Comprising at least one set of electrodes and a plurality of functional layers formed between the electrodes;
The functional layer is a layer having a light emitting function made of at least one organic semiconductor;
An organic electroluminescent device comprising a transition metal oxide layer having a thickness of at least 30 nm. The organic electroluminescent device according to claim 1,
The transition metal oxide layer is an organic electroluminescent device having a specific resistance of 100,000 ohm / cm ² or more. The organic electroluminescent device according to claim 1,
At least one of the at least one set of electrodes is formed on the surface of the translucent substrate, the transition metal oxide layer is formed on the electrode, and a layer having a light emitting function is disposed thereon. Organic electroluminescent device. The organic electroluminescent device according to claim 3,
An organic electroluminescent device comprising a buffer layer between the transition metal oxide layer and the layer having a light emitting function. The organic electroluminescent device according to claim 4, wherein
The organic electroluminescent device, wherein the buffer layer is an electron block layer. The organic electroluminescent device according to claim 5,
The buffer layer is an organic electroluminescent device including a polymer compound. An organic electroluminescent device according to any one of claims 1 to 6,
A pixel regulation layer is provided between the electrode and the layer having the light emitting function,
An organic electroluminescent element that defines a light emission region. The organic electroluminescent device according to claim 7,
An organic electroluminescent element in which the pixel regulating layer is an insulating film. The organic electroluminescent device according to claim 8, wherein
An organic electroluminescent element in which the pixel regulating layer is silicon oxide. The organic electroluminescent device according to claim 8, wherein
An organic electroluminescent device in which the pixel regulating layer is silicon nitride. The organic electroluminescent device according to claim 7,
An organic electroluminescent device in which the pixel regulating layer is made of a photoresist material. The organic electroluminescent device according to any one of claims 7 to 11,
An organic electroluminescent device in which the entire surface of the pixel regulating layer is covered with a transition metal oxide layer, and a layer having a light emitting function is formed thereon. The organic electroluminescent device according to claim 12, wherein
The layer having the light emitting function is an organic electroluminescent element formed by an inkjet method. The organic electroluminescent device according to any one of claims 7 to 11,
An organic electroluminescent element in which the transition metal oxide layer is formed under the pixel regulating layer, and the transition metal oxide layer is in contact with the functional layer only in a light emitting region. The organic electroluminescent device according to any one of claims 1 to 14,
An organic electroluminescent device in which the transition metal oxide layer is a molybdenum oxide layer. The organic electroluminescent device according to claim 15,
An organic electroluminescent device in which the molybdenum oxide layer has a thickness of 40 nm or more. The organic electroluminescent device according to claim 9, wherein
An organic electroluminescent element having a film thickness of the pixel regulating layer of 20 nm to 100 nm. The organic electroluminescent device according to any one of claims 1 to 17,
The organic electroluminescent element in which the layer having the light emitting function includes at least one polymer light emitting material. The organic electroluminescent device according to claim 1,
The organic electroluminescent element in which the layer having the light emitting function contains a polymer compound containing a fluorene ring. The organic electroluminescent device according to claim 19, wherein
The organic electroluminescent device, wherein the layer having a light emitting function contains polyfluorene represented by the following general formula (I) and derivatives thereof (R1 and R2 each represent a substituent).
The organic electroluminescent device according to claim 20, wherein
The organic electroluminescent element in which the layer having the light emitting function contains a phenylene vinylene group. The organic electroluminescent device according to claim 21, wherein
The organic electroluminescent element characterized in that the layer having a light emitting function contains polyphenylene vinylene represented by the following general formula (II) and derivatives thereof (R3 and R4 each represent a substituent).
The organic electroluminescent device according to claim 18, wherein
The functional layer is an organic electroluminescent device including a layer having a light emitting function made of at least one polymer material having a tree-like multi-branched structure and a charge injection layer made of at least one inorganic material. The organic electroluminescent device according to claim 23, wherein
The layer having a light emitting function is an organic electroluminescent device comprising a dendritic multi-branched polymer structure having a light emitting structural unit as a center. The organic electroluminescent device according to claim 23, wherein
The layer having a light emitting function is an organic electroluminescent device comprising a dendritic multi-branched low molecular structure having a light emitting structural unit as a center. The organic electroluminescent device according to claim 1,
The anode which is one electrode of the set of electrodes is formed on a translucent substrate,
A molybdenum oxide layer as a transition metal oxide layer formed on the anode;
A hole injection layer;
A layer having the light emitting function;
An electron injection layer formed on the layer having a light emitting function so as to face the hole injection layer;
An organic electroluminescent device in which a cathode which is the other electrode of the set of electrodes disposed on the electron injection layer is sequentially stacked.   27. A display device in which the organic electroluminescent elements according to claim 1 are two-dimensionally arranged.   27. An exposure apparatus in which the organic electroluminescent elements according to any one of claims 1 to 26 are arranged in a line to constitute a light emitting unit. It is a manufacturing method of the organic electroluminescent element in any one of Claims 1 thru | or 26, Comprising:
Forming a transition metal oxide layer having a thickness of 30 nm or more on the substrate surface on which one electrode of the set of electrodes is formed;
And a step of forming a layer having a light emitting function thereon by an ink jet method. A method for producing an organic electroluminescent device according to claim 29, comprising:
A method for producing an organic electroluminescent device, comprising a step of forming a pixel regulating layer prior to the formation of a transition metal oxide layer, wherein a layer having a light emitting function is formed on the transition metal oxide layer. A method for producing an organic electroluminescent device according to claim 29, comprising:
An organic electroluminescence including a step of forming a pixel regulating layer after the formation of the transition metal oxide layer, and forming a layer having a light emitting function on the transition metal oxide layer on which the pixel regulating layer is formed. A manufacturing method of a cent element.