JP2008091174A - LIGHT EMITTING DEVICE AND ELECTRONIC DEVICE - Google Patents

Abstract

[Problem] To be able to manufacture with a simple manufacturing process, to easily achieve high definition, and to prevent a dark spot defect caused by a short circuit between the pixel electrode layer and a wiring in a contact portion. Provided are a light-emitting device and an electronic device.
A light-emitting device includes a substrate on which a plurality of light-emitting elements are arranged, a plurality of wirings formed on the substrate and respectively carrying a drive current of the plurality of light-emitting elements. A non-pixel region N other than the wiring layer 30 having a plurality of recesses 34 each having a plurality of wirings 33 at the bottom, and each light emitting element 20 is provided on the wiring layer 30, each including a pixel electrode 21, each having a recess A plurality of pixel electrode layers 41 in contact with the wiring 60 at 34 and a counter electrode layer 43 including the counter electrodes 23 of the plurality of light emitting elements 20 are provided. The counter electrode layer 43 overlaps the entire surface of the pixel region G and does not overlap any of the plurality of recesses 34.
[Selection] Figure 1

Description

  The present invention relates to a light emitting device and an electronic device including a light emitting element represented by OLED (Organic Light Emitting Diode).

  16 is a plan view showing a configuration of a conventional light emitting device 500, and FIG. 17 is a cross-sectional view taken along line A-A ′ of the light emitting device 500 shown in FIG. However, in these drawings, illustration of some members is omitted. As shown in these drawings, the light-emitting device 500 includes a substrate 510, a plurality of light-emitting elements 520 arranged on the substrate 510, and a plurality of drive circuits 530 that respectively drive the plurality of light-emitting elements 520. The light-emitting element 520 is an OLED and includes a light-emitting layer 22 and a pixel electrode 522 and a counter electrode 523 that sandwich the light-emitting layer therebetween.

  A wiring layer 550 is formed on the substrate 510. The wiring layer 550 includes a wiring 551 formed on the substrate 510 and a first insulating layer 552 formed on the wiring 551 and the substrate 510. The wiring 552 is electrically connected to the drive circuit 530. The first insulating layer 552 is formed with a plurality of recesses 553 each having a plurality of wirings 551 at the bottom.

  On the first insulating layer 552, the pixel electrode layer 41 is formed for each light emitting element 520. Each pixel electrode layer 41 includes a pixel electrode 522 and is in contact with the bottom (wiring 551) of the recess 553. That is, the recess 553 is a contact portion that establishes electrical connection between the pixel electrode layer 41 and the wiring 551. A second insulating layer 42 is formed on the pixel electrode layer 41 and the first insulating layer 552. The pixel electrode layer 41 is covered with the second insulating layer 42 except for a part of the pixel electrode layer (pixel electrode 522). On the pixel electrode layer 41 and the second insulating layer 42, the light emitting layer 22 is formed so as to cover all the pixel electrode layers 41. On the light emitting layer 22, a counter electrode layer 43 is formed so as to cover the light emitting layer 22. The counter electrode layer 43 includes all the counter electrodes 523.

  In the light emitting device 500, the second insulating layer 42 is sandwiched between the pixel electrode layer 41 and the counter electrode layer 43 in a region other than the region occupied by the light emitting element 520. The thickness of the second insulating layer 42 is as follows. It becomes relatively thin in a region 580 near the outside of the end surface of the first insulating layer 552 (near the wall of the recess 553). That is, in the region 580, the step coverage of the second insulating layer 42 is relatively poor, and the pressure resistance performance is relatively low. In the region 580, when a voltage exceeding the withstand voltage performance is applied, dielectric breakdown occurs, and the pixel electrode layer 41 and the counter electrode layer 43 are short-circuited. As a result, no current is supplied to the light-emitting element 520 that includes a part of the short-circuited electrode layer as an electrode, and the light-emitting element 520 becomes a dark spot defect.

  FIG. 18 is a diagram showing current-light quantity characteristics and voltage-current characteristics of a general OLED. OLEDs deteriorate with use, and in the figure, characteristic lines T1 and T2 indicate characteristics before deterioration, and characteristic lines T3 and T4 indicate characteristics after deterioration. In order to obtain the necessary light quantity P1, the current I1 and the voltage V1 are required before the deterioration of the OLED, but after the deterioration of the OLED, a current I2 larger than the current I1 and a voltage V2 larger than the voltage V1 are necessary. . In a light emitting device including a circuit for performing such voltage correction, there is a high possibility that a voltage exceeding the withstand voltage performance is applied in the region 580 after the OLED is deteriorated. That is, in reality, it is necessary to consider even after the deterioration of the OLED in order to prevent a dark spot defect due to a short circuit in the contact portion, which is not easy.

Patent Document 1 discloses a light emitting device having a counter electrode layer in a stripe shape or a slit shape. In this light emitting device, since the pixel electrode layer and the counter electrode layer do not face each other in the contact portion, no short circuit occurs in the contact portion. Therefore, it is possible to prevent a dark spot defect due to a short circuit in the contact portion.
Japanese Patent Laying-Open No. 2006-114498 (FIGS. 5a, 5b, and 5c)

  There is a demand for higher definition in a light-emitting device having a plurality of light-emitting elements. Therefore, it is an important feature that the light emitting elements can be arranged at a narrow pitch. In order to realize a narrow pitch, it is necessary to sufficiently reduce the planar size of the contact portion. Generally, it is 100 μm square or less. On the other hand, since a counter electrode is essential for the light emitting element, in order to reduce the pitch in the light emitting device described in Patent Document 1, it is necessary to sufficiently narrow a region where the counter electrode layer is not formed.

  However, in the light emitting device described in Patent Document 1, it is difficult to sufficiently narrow a region where the counter electrode layer is not formed. For the formation of the counter electrode layer, it is necessary to use a stripe-shaped or slit-shaped patterning mask, and the processing accuracy and the alignment accuracy between the patterning mask and the substrate are insufficient. This is because it must be secured widely. In the first place, there is a disadvantage that the manufacturing process becomes complicated because a patterning mask having a complicated shape must be manufactured with high accuracy.

  The present invention has been made on the basis of the above-described background, can be manufactured by a simple manufacturing process, can be easily made high definition, and can provide electrical connection between the pixel electrode layer and the wiring. It is an object of the present invention to provide a light-emitting device and an electronic device that can prevent a dark spot defect due to a short circuit between the two.

A light-emitting device according to the present invention includes a substrate on which a plurality of light-emitting elements each having a light-emitting layer and a pixel electrode and a counter electrode sandwiching the light-emitting layer are arranged, the substrate being formed on the substrate, A plurality of wirings that respectively drive driving currents, and the plurality of light emitting elements are arranged in a non-pixel region other than a continuous pixel region including a plurality of first regions occupied by the plurality of light emitting elements and a second region between the plurality of light emitting elements. A wiring layer having a plurality of recesses each having a bottom of the wiring and a wiring layer formed on the wiring layer and provided for each of the light-emitting elements, each including the pixel electrode, wherein each of the recesses is in contact with the wiring A plurality of pixel electrode layers and a counter electrode layer formed on the light emitting layer and including a counter electrode of the plurality of light emitting elements, the counter electrode layer overlapping the entire surface of the pixel region, Any of multiple recesses Do not overlap also, characterized in that.
According to this light emitting device, the contact portion (concave portion) that should not overlap with the counter electrode layer is disposed in the non-pixel region other than the continuous pixel region. The shape may be a simple shape such as a rectangle, and high definition can be achieved while maintaining the formation accuracy of the counter electrode layer as a general accuracy. That is, this light-emitting device has an advantage that it can be manufactured with a simple manufacturing process and high definition is easy.
Further, in this light emitting device, since the pixel electrode layer and the counter electrode layer do not face each other in the contact portion, a short circuit does not occur in the contact portion. Therefore, according to this light emitting device, it is possible to prevent dark spot defects due to a short circuit in the contact portion.
Further, according to this light emitting device, since the contact portion (concave portion) is not disposed in the second region between the light emitting elements, the thickness of the light emitting layer can be made more uniform when the light emitting layer is formed by a coating method or a vapor deposition method. can do. Examples of the coating method include a spin coating method, a slit coating method, and an ink jet method.

  In the above light-emitting device, if the arrangement of the plurality of contact portions in the non-pixel region is arbitrary, the length of the conductive path between the pixel electrode and the contact portion varies between the light-emitting elements. This leads to variations in the resistance value of the conductive path between the light emitting elements, and consequently variations in the amount of light. Therefore, the plurality of recesses may be arranged along the end of the counter electrode layer. By doing so, there is a high possibility that the length of the conductive path is substantially the same between the light emitting elements.

However, in this aspect, when a plurality of light emitting elements are arranged in a straight line, it is necessary to arrange a large number of contact parts that require a certain size in a straight line, and the arrangement of the contact parts is a large size of the light emitting device. There is a risk that Further, even if the lengths of the conductive paths are substantially the same among the light emitting elements, the resistance values of the conductive paths are not necessarily the same. In addition, when the conductive path is long as in the light emitting device described above, variation in resistance value of the conductive path between the light emitting elements tends to increase.
Therefore, it is preferable that the light emitting device includes a plurality of constant current circuits that supply currents corresponding to a required light amount to the plurality of wirings. In this light emitting device, even if the resistance value of the conductive path varies between the light emitting elements, this variation does not affect the driving current of the light emitting element. Therefore, according to this light emitting device, it is possible to sufficiently reduce the variation in the amount of light caused by the variation in the resistance value of the conductive path between the light emitting elements. Further, in this light emitting device, since the contact portion can be freely arranged, the arrangement of the contact portion does not cause an increase in size of the light emitting device.

  In the light emitting device, the plurality of constant current circuits may be included in the wiring layer, or may include a plurality of mounting terminals electrically connected to the plurality of wirings. Each of the constant current circuits may be electrically connected to the plurality of mounting terminals.

  In each of the light-emitting devices described above, the plurality of light-emitting elements are divided into two columns, and the concave portion corresponding to the light-emitting element in one of the two columns is located between the column and the other column. It may be formed at a position sandwiched between. According to this light emitting device, the conductive path between the pixel electrode and the contact portion can be shortened in the pixel region. An example of the light-emitting device in which the plurality of light-emitting elements are divided into two rows is an exposure device that forms a latent image by irradiating the image carrier with light in an electrophotographic image forming apparatus.

  An electronic apparatus according to the present invention includes any one of the light emitting devices described above. Therefore, there are effects resulting from the various effects described above.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the drawings, the ratio of dimensions of each part is appropriately changed from the actual one.

<First Embodiment>
FIG. 1 is a plan view showing a configuration of a light emitting device 1 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the light emitting device 1 shown in FIG. However, in these drawings, illustration of some members is omitted. The light emitting device 1 is used as an exposure device that forms a latent image by irradiating an image carrier with light in an electrophotographic image forming apparatus.

  The light emitting device 1 includes a substrate 10. A plurality of connection terminals (not shown) are formed at the end of the substrate 10. To these connection terminals, various signals such as a start pulse SP and a clock signal CLK, and a power supply voltage such as a high potential Vel and a low potential Vss are supplied from an external circuit. On the substrate 10, a plurality of light emitting elements (pixels) 20 are arranged in two rows in a staggered manner. Each light emitting element 20 is specifically an OLED, and includes a pixel electrode 21 on the substrate 10 side, a counter electrode 23, and a light emitting layer 22 sandwiched between both electrodes.

  The region on the substrate 10 is divided into a pixel region G in which pixels are arranged and a non-pixel region N other than the pixel region G. The pixel region G is a continuous region, is surrounded by the non-pixel region N, and includes a plurality of first regions G1 occupied by the plurality of light emitting elements 20 and a second region G2 between the plurality of light emitting elements 20. The regions included in the pixel region G are only a plurality of first regions G1 and second regions G2. If a non-pixel area other than the pixel area can be secured, an area including a plurality of first areas G1, second areas G2, and other areas can be regarded as a pixel area.

  A wiring layer 30 including wirings and circuits is formed on the substrate 10. The wiring layer 30 includes a plurality of layers, and includes one or more metal layers, one or more insulating layers, and a semiconductor layer. These layers constitute wirings and circuits. That is, the circuit is formed by film formation on the substrate 10. In this formation, for example, LTPS (low temperature polysilicon) -TFT (Thin Film Transistor) technology is used.

  The wirings and circuits in the wiring layer 30 include a plurality of driving circuits 31 that respectively drive a plurality of pixels, a plurality of wirings 33 that extend from the plurality of driving circuits 31 one by one, and data that specifies the amount of light of each pixel. A plurality of data lines DL for supplying a signal to the driving circuit 31 for driving the pixel, a scanning circuit 32 for outputting a selection signal for selecting a part of the driving circuits 31 from the plurality of driving circuits 31, and a selection signal A plurality of selection lines SL for supplying each of the drive circuits 31 and power supply lines L1 and L2 (not shown in FIGS. 1 and 2) for supplying a power supply potential (V1, V2) to each of the drive circuits 31. It can be illustrated. Each drive circuit 31 causes a drive current corresponding to the data signal supplied at the time of selection to flow through the wiring 33.

  A plurality of recesses 34 are formed in the non-pixel region N on the upper surface side of the wiring layer 30. The plurality of recesses 34 are provided corresponding to the plurality of pixels, respectively. The uppermost layer of the wiring layer 30 is a first insulating layer 35, and each recess 34 has an end portion of the first insulating layer 35 as a wall and a part of the wiring 33 corresponding to the recess 34 as a bottom. The recess 34 is formed, for example, in the non-pixel region N by forming a through hole in the uppermost insulating layer to expose a part of the upper surface of the lower wiring 33.

  A plurality of pixel electrode layers 41 are formed of a conductive material on the wiring layer 30 (first insulating layer 35). The plurality of pixel electrode layers 41 are provided corresponding to the plurality of pixels, respectively. Each pixel electrode layer 41 extends over one first region G1, second region, and non-pixel region N, and includes a portion that becomes the pixel electrode 21 in the first region G1, and in the non-pixel region N, The upper surface of the wiring 33 (the portion exposed from the through hole) is in contact with the corresponding recess 34. That is, each concave portion 34 is a contact portion 34 for electrically connecting the pixel electrode 21 of the pixel corresponding to the concave portion 34 and the wiring 33 extending from the drive circuit 31 that drives the pixel.

  A second insulating layer 42 is formed on the plurality of pixel electrode layers 41 and the wiring layer 30 (first insulating layer 35). Each pixel electrode layer 41 is covered with the second insulating layer 42 except for a part thereof. A portion that is not covered with the second insulating layer 42 becomes an opening of the light emitting element 20. A light emitting layer 22 is formed on the pixel electrode layer 41 and the second insulating layer 42 so as to cover the plurality of pixel electrode layers 41. The light emitting layer 22 is formed of an organic EL (Electro Luminescent) material, and the portion of the light emitting layer 22 that overlaps the opening of the light emitting element 20 emits light with a light amount corresponding to the current flowing through the portion.

  On the light emitting layer 22, a rectangular counter electrode layer 43 is formed of a conductive material. The counter electrode layer 43 is formed by vapor deposition using a patterning mask. The counter electrode layer 43 extends over the pixel region G and the non-pixel region N. In the pixel region G, the counter electrode layer 43 overlaps the entire region of the light emitting layer 22 and includes a plurality of portions that become the plurality of counter electrodes 23. In the non-pixel region N, it does not overlap any of the contact portions 34. All the contact portions 34 are arranged in a line and linearly along one end (more specifically, substantially parallel to the end) of the four ends of the counter electrode layer 43. The occupied width, which is the width of each contact portion 34 in the direction parallel to the one end, is several tens of μm.

  The counter electrode layer 43 should be formed so as to overlap the entire region of the plurality of first regions G1. On the other hand, in the vapor deposition method using the patterning mask, the position accuracy of the edge of the formed layer is lowered. Therefore, in the present embodiment, the counter electrode layer 43 is formed so that the counter electrode layer 43 extends 100 μm or more from the periphery of the pixel region G. Further, as described above, the counter electrode layer 43 does not overlap any of the contact portions 34. Therefore, inevitably, the distance from the contact portion 34 is longer than 100 μm in any pixel.

  Although not shown, a sealing layer that protects the plurality of light emitting elements 20 from the outside air is provided on the counter electrode layer 43 and the light emitting layer 22. This sealing layer covers the pixel electrode layer 41, the light emitting layer 22 and the counter electrode layer 43. Note that the light emitting device 1 may be a bottom emission type in which light from the pixels is transmitted through the substrate 10 and emitted from the opposite side of the substrate 10. In the case of the bottom emission type, it is necessary to form a portion of the layer constituting the light emitting device 1 below the light emitting layer 22 so as to overlap the opening of the light emitting element 20 with a material having high light transmittance. In the case of the top emission type, it is necessary to form a portion of the layer constituting the light-emitting device 1 above the light-emitting layer 22 so as to overlap with the opening of the light-emitting element 20 with a material having high light transmittance.

  According to the light emitting device 1, the contact portion 34 that should not overlap the counter electrode layer 43 is disposed in the non-pixel region N other than the continuous pixel region G. Therefore, the shape of the counter electrode layer 43 is rectangular. However, it is possible to prevent the counter electrode layer 43 from overlapping any of the contact portions 34. Therefore, according to the light emitting device 1, the counter electrode layer 43 is formed using a patterning mask having a simple shape, and the pixel pitch is reduced, that is, the formation accuracy of the counter electrode layer 43 is kept at a general accuracy. High definition can be achieved. That is, the light-emitting device 1 has an advantage that it can be manufactured with a simple manufacturing process and high definition is easy.

  Further, in the light emitting device 1, since the pixel electrode layer 41 and the counter electrode layer 43 do not face each other in the contact portion 34, no short circuit occurs in the contact portion 34. Therefore, according to the light emitting device 1, it is possible to prevent dark spot defects due to a short circuit in the contact portion 34.

  By the way, in the conventional light emitting device, the distance from the contact portion is within 100 μm for any pixel. For this reason, the various problems according to the formation method of the light emitting layer have arisen. Various problems occurring in the conventional light emitting device will be described below for each method of forming the light emitting layer.

[A. Application method]
[A-1. Spin coating method or slit coating method]
When the light emitting layer is formed by spin coating or slit coating, the conventional light emitting device has a short distance from the contact portion for each pixel, and therefore a layer (insulating layer) immediately below the light emitting layer in the neighboring region of each pixel. ) Becomes large, and it becomes difficult to uniformly form a light emitting layer.
In addition, when the light emitting layer is formed by spin coating or slit coating, a large amount of organic EL material solution accumulates in the concave portion on the contact portion. However, in the conventional device, any pixel is connected to the contact portion. Since the distance is short, each pixel is greatly affected by the organic EL material solution accumulated in the recesses in the drying process of the organic EL material solution. Specifically, in each pixel, the thickness of the light emitting layer is thicker on the contact portion side where the drying of the organic EL material solution is slow, and thinner on the opposite side of the contact portion. This leads to nonuniformity in the amount of light and wavelength in the light emitting layer of each pixel.

[A-2. Inkjet method]
In the case of forming the light emitting layer by the inkjet method, in the conventional light emitting device, since the distance to the contact portion is close for any pixel, the step difference of the layer immediately below the light emitting layer is increased in the adjacent region of each pixel. In the pixel, the film thickness of the light emitting layer varies.
In addition, when the light emitting layer is formed by the ink jet method, if a leak occurs in the insulating layer on the contact portion, in the conventional device, since any pixel is close to the contact portion, erroneous light emission due to the leak current occurs. There is a fear.

[B. Vapor deposition method]
In the case where the light emitting layer is formed by vapor deposition, in the conventional light emitting device, since the distance from the contact portion is close for each pixel, the step difference of the layer immediately below the light emitting layer is increased in the adjacent region of each pixel, and the light emitting layer It becomes difficult to form a uniform film.
In addition, when the light emitting layer is formed by vapor deposition, if a leak occurs in the insulating layer on the contact portion, in the conventional device, since any pixel is close to the contact portion, erroneous light emission due to the leak current occurs. There is a fear.

  On the other hand, in the light emitting device 1, the distance from the contact portion 34 is longer than 100 μm for any pixel. That is, in the light emitting device 1, the distance from the contact portion 34 is sufficiently long for any pixel. Therefore, according to the light emitting device 1, the above-described various problems can be solved.

  In the light emitting device 1, as the light emitting element 20, an OLED having a configuration in which only the light emitting layer 20 is sandwiched between the pixel electrode 21 and the counter electrode 23 is illustrated, but in addition to the light emitting layer 20, a hole injection layer, a hole is formed. An OLED having a structure in which at least one layer of a transport layer, an electron block layer, a hole block layer, an electron transport layer, and an electron injection layer is also sandwiched may be used. Further, an inorganic EL element may be employed as the light emitting element 20. Further, the data signal may be a voltage signal or a current signal. In the former case, a voltage command type drive circuit is adopted as the drive circuit 31, and in the latter case, a current command type drive circuit is adopted as the drive circuit 31.

  FIG. 3 is a circuit diagram showing an example of the electrical configuration of a voltage command type drive circuit. The drive circuit 311 according to this example includes a drive transistor Tr1 for supplying a drive current to the light emitting element 20, and a control transistor Tr2 for controlling the drive transistor Tr1. The light emitting element 20 is interposed between the power supply lines L1 and L2, and the control transistor Tr2 is interposed between the light emitting element 20 and the power supply line L1. A control transistor Tr2 is interposed between the gate of the drive transistor Tr1 and the data line DL. The gate of the control transistor Tr2 is connected to the selection line SL.

  In the drive circuit 311, a drive current corresponding to the voltage level of the data signal flows through the light emitting element 20. However, the driving current of the light emitting element 20 depends on the values of the contact resistance R1 and the routing resistance R2 between the driving transistor Tr1 and the light emitting element 20. The contact resistance R1 is a resistance in the contact portion 34, and the routing resistance R2 is a resistance of a conductive path (pixel electrode layer 41) between the contact portion 34 and the pixel electrode 21. As is clear from FIG. 1, the value of the contact resistance R <b> 1 is substantially the same between the light emitting elements 20. On the other hand, the variation in the value of the routing resistor R2 decreases between the light emitting elements 20 in the same column, and increases between the light emitting elements 20 in different columns. Therefore, when the drive circuit 311 is employed as the drive circuit 31, it is difficult to avoid variations in the amount of light.

  If the arrangement pattern of the light emitting elements 20 is not in two rows and staggered but in a single row and linear, or if the arrangement pattern of the contact portions 34 is in two rows and staggered, the distance from the contact portion 34 is set to the distance from the light emitting elements 20. Therefore, even when the drive circuit 311 is adopted as the drive circuit 31, it is possible to reduce the variation in the amount of light. However, in the former form, it is necessary to arrange a large number of contact portions 34 that require a certain size in a line and in a straight line, and therefore the arrangement of the contact portions may cause an increase in the size of the light emitting device. In the first place, even if the lengths of the conductive paths are substantially the same between the light emitting elements, the resistance values of the conductive paths are not necessarily the same. Further, since the accuracy of formation of the pixel electrode layer 41, that is, the variation in the line width of the conductive path having the routing resistance R2, is uniform throughout the entire region, the resistance R2 between the light emitting elements 20 when the conductive path is long. The variation of the value tends to increase. On the other hand, in the light emitting device 1, the distance between the light emitting element 20 and the contact portion 34 is longer than 100 μm. As can be seen from the above, as long as a voltage command type driving circuit is employed as the driving circuit 31, it is difficult to sufficiently reduce the variation in the amount of light caused by the variation in the routing resistance R2.

  FIG. 4 is a circuit diagram showing an example of the electrical configuration of a current command type drive circuit. The drive circuit 312 according to this example is a current mirror circuit (constant current circuit), and includes a transistor Tr3 in addition to the drive transistor Tr1 and the control transistor Tr2. The transistor Tr3 is interposed between the control transistor Tr2 and the power supply line L2, and the gate thereof is connected to the gate of the drive transistor Tr1. In the drive circuit 312, the same drive current as the data signal flows through the light emitting element 20.

  The reference resistor R3 between the control transistor Tr3 and the power supply line L2 is a resistor for compensating for the fluctuation of the routing resistor R2, and its value is substantially the same as the value of the routing resistor R2. In order to make the value of the reference resistor R3 and the value of the routing resistor R2 substantially the same, in the drive circuit 312, the conductive path having substantially the same line width and length as the conductive path having the routing resistor R2 is used as the routing resistor R2. It is provided adjacent to the conductive path. It is preferable that the conductive path having the reference resistance R3 is a part of the pixel electrode layer 41 in order to make the variation between both the conductive paths sufficiently. In this case, two pixel electrode layers 41 correspond to one light emitting element 20.

  According to the drive circuit 312, even if the routing resistance R <b> 2 fluctuates, if a predetermined current is supplied, a drive current that compensates for the fluctuation can be supplied to the light emitting element 20. Therefore, if a current command type driving circuit is adopted as the driving circuit 31, even in the light emitting device 1 having a variation in the distance between the light emitting element 20 and the contact portion 34, the variation in the amount of light caused by the variation in the routing resistance R2. Can be sufficiently reduced. Further, in this light emitting device, since the contact portion can be freely arranged, the arrangement of the contact portion does not cause an increase in size of the light emitting device.

  5 to 8 are diagrams schematically showing examples of arrangement patterns of the contact portions 34. As shown in these drawings, the contact portions 34 may be arranged at equal intervals (see FIG. 5), may be arranged at non-equal intervals (see FIG. 6), or are arranged in a plurality of rows and staggered shapes. They may be arranged (see FIG. 7) or arranged in a plurality of rows and in a straight line (see FIG. 8).

  9 to 12 are circuit diagrams illustrating configuration examples around the driving transistor Tr1. In these drawings, VEL is a power supply potential on the high potential side, and Vback is a potential equal to or higher than VEL. As shown in these drawings, an N-channel transistor or a P-channel transistor can be used as the drive transistor Tr1. In the case where an N-channel transistor is employed as the drive transistor Tr1, a reduction in manufacturing cost of the light emitting device 1 can be expected. Further, as shown in these drawings, a reverse bias can be applied when the light emitting element 20 is turned off, or a configuration in which no reverse bias is applied can be employed. In the case of a configuration in which a reverse bias is applied, deterioration of the light emitting element 20 can be suppressed.

<Second Embodiment>
FIG. 13 is a plan view showing the configuration of the light emitting device 2 according to the second embodiment of the present invention. In this figure, illustration of some members is omitted. The light emitting device 2 is different from the light emitting device 1 in that a driving circuit 31 and a scanning circuit 32 are provided. In the light emitting device 1, it is provided by film formation on the substrate 10, but in the light emitting device 2, it is provided by attaching a plurality of driver ICs (integrated circuits) 40.

  A plurality of mounting terminals 45 for mounting a plurality of driver ICs 40 are provided on the substrate 10. Each drive circuit 31 in the driver IC 40 is electrically connected to the mounting terminal 45. Each driver IC 40 is mounted in association with a plurality of pixels, and functions as a drive circuit 31 and a scanning circuit 32 for each corresponding pixel. The plurality of driver ICs 40 are arranged in the pixel arrangement direction along the end of the counter electrode layer 43, and are divided into two groups according to their mounting positions. Both groups are opposed to each other with the counter electrode layer 43 interposed therebetween.

  A plurality of contact portions (concave portions) 50 are provided between the counter electrode layer 43 and each driver IC 40. The contact part 50 corresponds to the contact part 34 in the light emitting device 1. A wiring 60 corresponding to the wiring 33 extends from the mounting terminal 45, and a part thereof is the bottom of the contact portion 50. Each contact portion 50 is covered with the pixel electrode layer 70. The pixel electrode layer 70 is different from the pixel electrode layer 41 only in shape and dimensions.

  The pixels are arranged in two rows and zigzag, and the contact portions 50 corresponding to the pixels in one column are formed at positions where the column is sandwiched between the other column. That is, in FIG. 13, the contact portion 50 corresponding to the upper row of the light emitting elements 20 in the two rows of the light emitting devices 20 is located above the counter electrode layer 43 in the drawing, and the lower row of the light emitting elements 20 in the drawing. The contact portion 50 corresponding to the element 20 is located below the counter electrode layer 43 in the drawing.

According to the light emitting device 2, the same effect as the light emitting device 1 can be obtained.
Further, according to the light emitting device 2, it is possible to replace only the defective driver IC 40. Therefore, improvement in the yield of the light emitting device can be expected.
Further, according to the light emitting device 2, the contact portion 50 corresponding to the pixel in one column is formed at a position sandwiching the column with the other column. The conductive path between the two can be shortened. As described above, if the conductive path is long, variation in the value of the resistance R2 (see FIG. 3 or FIG. 4) between the light emitting elements 20 tends to increase. Therefore, shortening the conductive path is advantageous in reducing variation in light quantity. It is an effect.

<Electronic equipment>
FIG. 14 is a longitudinal sectional view showing an example of an image forming apparatus using the light emitting device 1 or 2 as an exposure device. This image forming apparatus is a tandem type full color image forming apparatus using a belt intermediate transfer body system.

  In this image forming apparatus, four exposure apparatuses 90K, 90C, 90M, and 90Y having the same configuration are exposed positions of four photosensitive drums (image carriers) 110K, 110C, 110M, and 110Y having the same configuration. Respectively. The exposure devices 90K, 90C, 90M, and 90Y are the light emitting devices 1 and 2 described above.

  As shown in this figure, this image forming apparatus is provided with a driving roller 121 and a driven roller 122, and an endless intermediate transfer belt 120 is wound around these rollers 121 and 122, as indicated by arrows. Thus, the periphery of the rollers 121 and 122 is rotated. Although not shown, tension applying means such as a tension roller that applies tension to the intermediate transfer belt 120 may be provided.

  Around the intermediate transfer belt 120, photosensitive drums 110K, 110C, 110M, and 110Y having photosensitive layers on four outer peripheral surfaces are arranged at predetermined intervals. The subscripts K, C, M, and Y mean that they are used to form black, cyan, magenta, and yellow visible images, respectively. The same applies to other members. The photosensitive drums 110K, 110C, 110M, and 110Y are rotationally driven in synchronization with the driving of the intermediate transfer belt 120.

  Around each photosensitive drum 110 (K, C, M, Y), there is a corona charger 111 (K, C, M, Y), an exposure device 90 (K, C, M, Y), and a developing device. 114 (K, C, M, Y) are arranged. The corona charger 111 (K, C, M, Y) uniformly charges the outer peripheral surface of the corresponding photosensitive drum 110 (K, C, M, Y). The exposure device 90 (K, C, M, Y) writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum. Each exposure device 90 (K, C, M, Y) is installed such that the arrangement direction of the plurality of light emitting elements is along the bus (main scanning direction) of the photosensitive drum 110 (K, C, M, Y). . The electrostatic latent image is written by irradiating the photosensitive drum with light from the plurality of light emitting elements. The developing device 114 (K, C, M, Y) forms a visible image, that is, a visible image on the photosensitive drum by attaching toner as a developer to the electrostatic latent image.

  The black, cyan, magenta, and yellow developed images formed by the four-color single-color image forming station are sequentially transferred onto the intermediate transfer belt 120 to be superimposed on the intermediate transfer belt 120. As a result, a full-color visible image is obtained. Four primary transfer corotrons (transfer devices) 112 (K, C, M, Y) are arranged inside the intermediate transfer belt 120. The primary transfer corotron 112 (K, C, M, Y) is disposed in the vicinity of the photosensitive drum 110 (K, C, M, Y), and the photosensitive drum 110 (K, C, M, Y). The electrostatic image is electrostatically attracted from the toner image to transfer the visible image to the intermediate transfer belt 120 passing between the photosensitive drum and the primary transfer corotron.

  A sheet 102 as an object on which an image is to be finally formed is fed one by one from the sheet feeding cassette 101 by the pickup roller 103, and between the intermediate transfer belt 120 and the secondary transfer roller 126 in contact with the driving roller 121. Sent to the nip. The full-color visible image on the intermediate transfer belt 120 is secondarily transferred to one side of the sheet 102 by the secondary transfer roller 126 and fixed on the sheet 102 through the fixing roller pair 127 as a fixing unit. . Thereafter, the sheet 102 is discharged onto a paper discharge cassette formed in the upper part of the apparatus by a paper discharge roller pair 128.

  FIG. 15 is a longitudinal sectional view showing an example of another image forming apparatus using the light emitting device 1 or 2 as an exposure device. This image forming apparatus is a rotary developing type full-color image forming apparatus using a belt intermediate transfer body system.

  In the image forming apparatus shown in this figure, a corona charger 168, a rotary developing unit 161, an exposure device 167, and an intermediate transfer belt 169 are provided around a photosensitive drum (image carrier) 165.

  The corona charger 168 uniformly charges the outer peripheral surface of the photosensitive drum 165. The exposure device 167 writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum 165. The exposure device 167 is the light emitting device 1 or 2 described above, and is installed so that the arrangement direction of the plurality of light emitting elements is along the bus line (main scanning direction) of the photosensitive drum 165. The electrostatic latent image is written by irradiating the photosensitive drum with light from the plurality of light emitting elements.

  The developing unit 161 is a drum in which four developing units 163Y, 163C, 163M, and 163K are arranged at an angular interval of 90 °, and can rotate counterclockwise about the shaft 161a. The developing units 163Y, 163C, 163M, and 163K supply yellow, cyan, magenta, and black toners to the photosensitive drum 165, respectively, and attach the toner as a developer to the electrostatic latent image, thereby the photosensitive drum 165. A visible image, that is, a visible image is formed.

  The endless intermediate transfer belt 169 is wound around a driving roller 170a, a driven roller 170b, a primary transfer roller 166, and a tension roller, and is rotated around these rollers in a direction indicated by an arrow. The primary transfer roller 166 transfers the visible image to the intermediate transfer belt 169 that passes between the photosensitive drum and the primary transfer roller 166 by electrostatically attracting the visible image from the photosensitive drum 165.

  Specifically, in the first rotation of the photosensitive drum 165, an electrostatic latent image for a yellow (Y) image is written by the exposure device 167, and a developed image of the same color is formed by the developing device 163Y. The image is transferred to the transfer belt 169. Further, in the next rotation, an electrostatic latent image for a cyan (C) image is written by the exposure device 167, a developed image of the same color is formed by the developing device 163C, and intermediate transfer is performed so as to overlap the yellow developed image. Transferred to the belt 169. In this way, the yellow, cyan, magenta, and black visible images are sequentially superimposed on the intermediate transfer belt 169 while the photosensitive drum 9 rotates four times. As a result, a full-color visible image is formed on the transfer belt 169. It is formed. When images are finally formed on both sides of a sheet as an object on which an image is to be formed, the same color images of the front and back surfaces are transferred to the intermediate transfer belt 169, and then the front and back surfaces are transferred to the intermediate transfer belt 169. A full-color visible image is obtained on the intermediate transfer belt 169 by transferring the visible image of the next color.

  The image forming apparatus is provided with a sheet conveyance path 174 through which a sheet passes. The sheets are picked up one by one from the paper feed cassette 178 by the pick-up roller 179, advanced through the sheet transport path 174 by the transport roller, and between the intermediate transfer belt 169 and the secondary transfer roller 171 in contact with the drive roller 170a. Pass through the nip. The secondary transfer roller 171 transfers the developed image to one side of the sheet by electrostatically attracting a full-color developed image from the intermediate transfer belt 169 collectively. The secondary transfer roller 171 can be moved closer to and away from the intermediate transfer belt 169 by a clutch (not shown). The secondary transfer roller 171 is brought into contact with the intermediate transfer belt 169 when a full-color visible image is transferred onto the sheet, and is separated from the secondary transfer roller 171 while the visible image is superimposed on the intermediate transfer belt 169.

  The sheet on which the image has been transferred as described above is conveyed to the fixing device 172 and is passed between the heating roller 172a and the pressure roller 172b of the fixing device 172, whereby the visible image on the sheet is fixed. The sheet after the fixing process is drawn into the discharge roller pair 176 and proceeds in the direction of arrow F. In the case of double-sided printing, after most of the sheet passes through the paper discharge roller pair 176, the paper discharge roller pair 176 is rotated in the reverse direction and introduced into the double-sided printing conveyance path 175 as indicated by an arrow G. The Then, the visible image is transferred to the other surface of the sheet by the secondary transfer roller 171, the fixing process is performed again by the fixing device 172, and then the sheet is discharged by the discharge roller pair 176.

  Although the image forming apparatus has been exemplified above, the light emitting devices 1 and 2 can be applied to other electrophotographic image forming apparatuses. For example, an image forming apparatus that transfers a visible image directly from a photosensitive drum to a sheet without using an intermediate transfer belt, an image forming apparatus that forms a monochrome image, and an image forming that uses a photosensitive belt as an image carrier. It can also be applied to devices.

Examples of the electronic apparatus having the light emitting device 1 or 2 other than the image forming apparatus include a display device such as a personal computer, a mobile phone, and a personal digital assistant (PDA).
In addition, although OLED is employ | adopted as the light emitting element 20 in the light-emitting devices 1 and 2, you may employ | adopt light emitting elements other than OLED. As such a light emitting element, an inorganic EL element can be exemplified.

It is a figure which shows in plan the structure of the light-emitting device 1 which concerns on the 1st Embodiment of this invention. FIG. 2 is a cross-sectional view taken along line B-B ′ of the light emitting device 1 shown in FIG. 1. 3 is a circuit diagram illustrating an example of an electrical configuration of a voltage command type driving circuit of the light emitting device 1. FIG. 2 is a circuit diagram illustrating an example of an electrical configuration of a current command type driving circuit of the light emitting device 1. FIG. FIG. 4 is a diagram schematically showing an example of an arrangement pattern of contact portions 34 of the light emitting device 1. FIG. 6 is a diagram schematically illustrating an example of an arrangement pattern of contact portions. FIG. 6 is a diagram schematically illustrating an example of an arrangement pattern of contact portions. FIG. 6 is a diagram schematically illustrating an example of an arrangement pattern of contact portions. FIG. 6 is a circuit diagram illustrating a configuration example around a driving transistor Tr1. FIG. 6 is a circuit diagram illustrating a configuration example around a driving transistor Tr1. FIG. 6 is a circuit diagram illustrating a configuration example around a driving transistor Tr1. FIG. 6 is a circuit diagram illustrating a configuration example around a driving transistor Tr1. It is a figure which shows in plan the structure of the light-emitting device 2 which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows an example of the image forming apparatus which used the light-emitting device 10 as exposure apparatus. It is a longitudinal cross-sectional view which shows an example of the other image forming apparatus which used the light-emitting device 10 as exposure apparatus. It is a figure which shows the structure of the conventional light-emitting device 500 planarly. FIG. 17 is a cross-sectional view taken along line A-A ′ of the light emitting device 500 illustrated in FIG. 16. It is a figure which shows the electric current-light quantity characteristic and voltage-current characteristic of a general OLED.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Light-emitting device, 10 ... Board | substrate, 20 ... Light-emitting element, 21 ... Pixel electrode, 22 ... Light emitting layer, 23 ... Counter electrode, 30 ... Wiring layer, 31, 311 ... Drive circuit, 312 ... Drive circuit (constant current) Circuit), 33, 60 ... wiring, 34 ... contact part (concave portion), 35 ... first insulating layer, 40 ... driver IC, 41,70 ... pixel electrode layer, 42 ... second insulating layer, 43 ... counter electrode layer, 45: mounting terminal, 50: contact portion, G: pixel region, G1: first region, G2: second region, N: non-pixel region.

Claims (7)

A substrate on which a plurality of light emitting elements having a light emitting layer and a pixel electrode and a counter electrode sandwiching the light emitting layer are arranged;
A plurality of wirings that are formed on the substrate and through which drive currents of the plurality of light emitting elements are respectively passed; a plurality of first regions occupied by the plurality of light emitting elements; and a second region between the plurality of light emitting elements. A wiring layer having a plurality of recesses each having the plurality of wirings at the bottom in a non-pixel region other than a connected pixel region;
A plurality of pixel electrode layers formed on the wiring layer, provided for each of the light-emitting elements, each including the pixel electrode, each in contact with the wiring at the recess;
A counter electrode layer formed on the light emitting layer and including counter electrodes of the plurality of light emitting elements,
The counter electrode layer overlaps the entire surface of the pixel region and does not overlap any of the plurality of recesses.
A light emitting device characterized by that. The plurality of recesses are arranged along an end of the counter electrode layer.
The light-emitting device according to claim 1. Provided with a plurality of constant current circuits for supplying a current corresponding to the required light quantity to each of the plurality of wirings,
The light-emitting device according to claim 1. The plurality of constant current circuits are included in the wiring layer,
The light-emitting device according to claim 3. Comprising a plurality of mounting terminals electrically connected to the plurality of wires;
Each of the plurality of constant current circuits is electrically connected to the plurality of mounting terminals.
The light-emitting device according to claim 3. The plurality of light emitting elements are divided into two columns,
The recess corresponding to the light emitting element in one of the two columns is formed at a position sandwiching the column with the other column,
The light-emitting device according to claim 1, wherein the light-emitting device is a light-emitting device. The light-emitting device according to claim 1 is provided.
An electronic device characterized by that.

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