JP2011042038A - Line head and image forming device - Google Patents

Abstract

Since a circuit board for driving a light emitting element is stored inside a housing of a line head, heat generated by a driver IC or the like causes distortion due to thermal expansion in the housing, thereby causing image defects. There is a fear.
A housing 6, a light emitting substrate unit 7 including a first substrate 71 and a light emitting element 72 disposed on the first substrate 71, a housing 6, and a second light emitting substrate unit 7. The circuit board unit 8 including an interface circuit that is provided on the substrate 81 and the second board 81 and receives a signal for driving the light emitting element 72 is electrically connected to the light emitting board unit 7 and the circuit board unit 8. And a flexible printed circuit board 9 including wiring. The housing 6 forms a duct 67 that guides air that has flowed into the housing 6 to the outside of the housing 6.
[Selection] Figure 2

Description

  The present invention relates to a line head and an image forming apparatus having the line head.

2. Description of the Related Art Image forming apparatuses such as copying machines and printers that use an electrophotographic system are provided with exposure means for forming an electrostatic latent image by exposing the outer surface of a photoreceptor. As such exposure means, a line head having a structure in which a plurality of light emitting elements are arranged in the main scanning direction is known.
For example, in an image forming apparatus described in Patent Document 1 below, a line head using an organic EL light emitting element as a light source has been proposed. Since the light source of the organic EL light emitting element can accurately form the light emitting part by coating or vapor deposition using a mask on a single glass substrate, the position accuracy of the light emitting part is extremely high.

JP 2008-139558 A

  However, in an image forming apparatus as described in Patent Document 1, a circuit board for driving a light emitting element is stored inside a housing of a line head. For this reason, distortion due to thermal expansion occurs in the casing due to heat generation of the driver IC and the like, and there is a possibility of causing image defects due to deformation of the casing due to this distortion.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A line head according to this application example is provided in a housing, a light emitting substrate unit including a first substrate and a light emitting element provided on the first substrate, and the housing. A circuit board unit including a second substrate and an interface circuit that is provided on the second substrate and receives a signal for driving the light emitting element, and electrically connecting the light emitting substrate unit and the circuit board unit. And a flexible printed circuit board including wiring to be connected, wherein the casing forms a duct for guiding the air flowing into the casing to the outside of the casing.

  According to such a configuration, the circuit board unit is disposed inside the casing, and the casing forms a duct that guides the air flowing into the casing to the outside of the casing. Thereby, the heat generated inside the housing can be guided to the outside of the housing to be radiated, and the housing can be cooled. As a result, it is possible to prevent the housing from being distorted by heat generation inside the housing, and to suppress the occurrence of image defects due to deformation of the housing.

  Application Example 2 In the line head according to the application example described above, a semiconductor element in which at least a part of a drive circuit for driving the light emitting element is formed is disposed on the circuit board unit, and the semiconductor element is mounted on the casing. It is preferable to arrange in contact.

  According to such a configuration, the semiconductor element disposed on the circuit board unit comes into contact with the housing. Thereby, the heat generated in the semiconductor element can be radiated through the housing.

  Application Example 3 In the line head according to the application example described above, a semiconductor element in which at least a part of a drive circuit for driving the light emitting element is formed is disposed on the flexible printed board, and the semiconductor element is mounted on the casing. It is preferable to arrange in contact.

  According to such a configuration, the semiconductor element disposed on the flexible printed board comes into contact with the housing. Thereby, the heat generated in the semiconductor element can be radiated through the housing.

  Application Example 4 In the line head according to the application example described above, it is preferable that the line head includes a fan unit that generates an air flow in the duct.

  According to such a configuration, an air flow can be generated in the duct by the fan portion, and heat generated inside the casing can be guided to the outside of the casing to be radiated.

  Application Example 5 An image forming apparatus according to this application example includes a latent image carrier and a line head that exposes the latent image carrier, and the line head includes a housing and a first substrate. And a light emitting substrate unit including a light emitting element provided on the first substrate, and a second substrate and the second substrate provided in the housing to drive the light emitting element. A circuit board unit including an interface circuit to which a signal is input; and a flexible printed circuit including a wiring for electrically connecting the light emitting board unit and the circuit board unit. A duct is formed to guide the air flowing into the outside to the outside of the casing.

  According to such a configuration, the circuit board unit is disposed inside the case of the line head, and the case forms a duct that guides the air flowing into the case to the outside of the case. Thereby, the heat generated inside the housing can be guided to the outside of the housing to be radiated, and the housing can be cooled. As a result, it is possible to prevent the housing from being distorted by heat generation inside the housing, and to suppress the occurrence of image defects due to deformation of the housing.

  Application Example 6 In the image forming apparatus according to the application example described above, it is preferable that a fan unit that generates an air flow in the duct is provided at a position facing the opening of the duct formed by the housing.

  According to such a configuration, an air flow is generated in the duct by the fan unit disposed at a position facing the opening of the duct, and the heat generated inside the casing is guided to the outside of the casing to dissipate heat. be able to.

  Application Example 7 In the image forming apparatus according to the application example described above, a second duct that communicates with an opening of a duct formed by the casing, and an inside of the duct formed by the casing via the second duct It is preferable to have a fan part that generates an air flow.

  According to such a configuration, an air flow is generated in the duct formed by the casing through the second duct from the fan section, and the heat generated inside the casing is guided to the outside of the casing. It can dissipate heat.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. FIG. 3 is a cross-sectional view of a line head provided in the image forming apparatus. The perspective view which shows the line head provided with the fan part. Sectional drawing which shows schematic structure of each light emitting element with which the line head was equipped. The figure which shows the structure of the control system of a line head. The figure which shows the structure of a passive type drive circuit. The cross-sectional view of the line head in 2nd Embodiment. The cross-sectional view of the line head in 3rd Embodiment. FIG. 10 is a perspective view of the periphery of a line head provided in each image forming station in a fourth embodiment. Schematic which shows the whole structure of the image forming apparatus which concerns on 5th Embodiment.

(First embodiment)
The image forming apparatus according to the first embodiment will be described below with reference to the drawings.

(Image forming device)
FIG. 1 is a schematic diagram illustrating the overall configuration of the image forming apparatus according to the first embodiment. An image forming apparatus 1 shown in FIG. 1 is an electrophotographic printer that records an image on a recording medium P by a series of image forming processes including a charging process, an exposure process, a developing process, a transfer process, and a fixing process. The image forming apparatus 1 according to the present embodiment is a color printer that employs a so-called tandem method.

As shown in FIG. 1, the image forming apparatus 1 includes an image forming unit 10 for a charging process, an exposure process, and a developing process, a transfer unit 20 for a transfer process, a fixing unit 30 for a fixing process, A transport mechanism 40 for transporting a recording medium P such as paper and a paper feed unit 50 for supplying the recording medium P to the transport mechanism 40 are provided.
The image forming unit 10 includes an image forming station 10Y that forms a yellow toner image, an image forming station 10M that forms a magenta toner image, an image forming station 10C that forms a cyan toner image, and a black toner image. Four image forming stations including image forming stations 10K to be formed are provided.

  Each of the image forming stations 10Y, 10M, 10C, and 10K includes a photosensitive drum (photosensitive member) 11 that carries an electrostatic latent image, and a charging unit 12 and a line head (exposure) are disposed around (outer peripheral side). A unit) 13, a developing device 14, and a cleaning unit 15. Here, the configurations of the image forming stations 10Y, 10M, 10C, and 10K are substantially the same except that the colors of the toners used are different.

The photosensitive drum 11 has a cylindrical shape as a whole, and can be rotated in the direction of the arrow of the photosensitive drum 11 shown in FIG. A photosensitive layer (not shown) is provided near the outer peripheral surface (cylindrical surface) of the photosensitive drum 11. The outer peripheral surface of the photosensitive drum 11 has a light receiving surface 111 (see FIG. 2) that receives light L (emitted light) from the line head 13.
The charging unit 12 uniformly charges the light receiving surface 111 of the photosensitive drum 11 by corona charging or the like.

  The line head 13 receives image information from a host computer such as a personal computer (not shown), and irradiates the light L toward the light receiving surface 111 of the photosensitive drum 11 according to the image information. When the light L is irradiated onto the light receiving surface 111 of the uniformly charged photosensitive drum 11, a latent image (electrostatic latent image) corresponding to the light L irradiation pattern is formed on the light receiving surface 111. Details of the configuration of the line head 13 will be described later.

The developing device 14 has a storage unit (not shown) that stores toner, and supplies and applies toner from the storage unit to the light receiving surface 111 of the photosensitive drum 11. When toner is applied to the light receiving surface 111 on which the electrostatic latent image is formed, the latent image is visualized (developed) as a toner image.
The cleaning unit 15 includes a rubber cleaning blade 151 that contacts the light receiving surface 111 of the photosensitive drum 11, and scrapes and removes toner remaining on the photosensitive drum 11 after the primary transfer described later by the cleaning blade 151.

The transfer unit 20 collectively transfers the toner images of the respective colors formed on the photosensitive drums 11 of the image forming stations 10Y, 10M, 10C, and 10K to the recording medium P.
In each of the image forming stations 10Y, 10M, 10C, and 10K, charging of the light receiving surface 111 of the photosensitive drum 11 by the charging unit 12, exposure of the light receiving surface 111 by the line head 13, and development while the photosensitive drum 11 rotates once. The supply of toner to the light receiving surface 111 by the apparatus 14, the primary transfer of the toner image to the intermediate transfer belt 21 by the primary transfer roller 22, and the cleaning of the light receiving surface 111 by the cleaning unit 15 are sequentially performed.

The transfer unit 20 includes an endless belt-like intermediate transfer belt 21, and the intermediate transfer belt 21 includes a plurality of (four in the configuration illustrated in FIG. 1) primary transfer rollers 22, driving rollers 23, and driven rollers 24. And stretched. Then, the intermediate transfer belt 21 is driven to rotate at the same peripheral speed as the peripheral speed of the photosensitive drum 11 by the rotation of the driving roller 23.
Each primary transfer roller 22 is disposed opposite to the corresponding photosensitive drum 11 via an intermediate transfer belt 21, and transfers (primary transfer) a single color toner image on the photosensitive drum 11 to the intermediate transfer belt 21. A primary transfer voltage (primary transfer bias) having a polarity opposite to the charging polarity of the toner is applied to the primary transfer roller 22 at the time of primary transfer.

  Here, a toner image of at least one of yellow, magenta, cyan, and black is carried on the intermediate transfer belt 21. For example, when a full-color image is formed, four color toner images of yellow, magenta, cyan, and black are sequentially transferred onto the intermediate transfer belt 21 to form a full-color toner image as an intermediate transfer image.

  Further, the transfer unit 20 includes a secondary transfer roller 25 disposed to face the driving roller 23 via the intermediate transfer belt 21, and a cleaning unit 26 disposed to face the driven roller 24 via the intermediate transfer belt 21. have.

The secondary transfer roller 25 transfers a single-color or full-color toner image (intermediate transfer image) formed on the intermediate transfer belt 21 to a recording medium P such as paper, film, or cloth supplied from the paper supply unit 50. (Secondary transfer). The secondary transfer roller 25 is pressed against the intermediate transfer belt 21 and applied with a secondary transfer voltage (secondary transfer bias) during secondary transfer. Further, at the time of secondary transfer, the driving roller 23 also functions as a backup roller for the secondary transfer roller 25.
The cleaning unit 26 includes a rubber cleaning blade 261 that contacts the surface of the intermediate transfer belt 21, and scrapes and removes toner remaining on the intermediate transfer belt 21 after the secondary transfer by the cleaning blade 261.

  The fixing unit 30 includes a fixing roller 301 and a pressure roller 302 pressed against the fixing roller 301, and is configured so that the recording medium P passes between the fixing roller 301 and the pressure roller 302. ing. A heater for heating the outer peripheral surface of the fixing roller 301 is built in the fixing roller 301. In the fixing unit 30, the recording medium P that has undergone the secondary transfer of the toner image is heated and pressed while passing between the fixing roller 301 and the pressure roller 302, whereby the toner image is recorded on the recording medium P. And fixed as a permanent image.

The conveyance mechanism 40 includes a registration roller pair 41 that conveys the recording medium P to the secondary transfer portion between the secondary transfer roller 25 and the intermediate transfer belt 21 while feeding the recording medium P, and has been subjected to fixing processing in the fixing unit 30. And a pair of conveying rollers 42, 43, and 44 for nipping and conveying the recording medium P.
When image formation is performed only on one surface of the recording medium P, the transport mechanism 40 sandwiches and transports the recording medium P fixed on one surface by the fixing unit 30 by the transport roller pair 42 to form an image. Discharge to the outside of the device 1. Further, when forming an image on both surfaces of the recording medium P, the transport mechanism 40 temporarily holds the recording medium P fixed on one surface by the fixing unit 30 by the transport roller pair 42 and then moves the transport roller pair 42. The reversing drive is performed, and the conveyance roller pairs 43 and 44 are driven. Then, the recording medium P is turned upside down and returned to the registration roller pair 41, and an image is formed on the other surface of the recording medium P by the same operation as described above.

  The paper feed unit 50 includes a paper feed cassette 51 that stores unused recording media P, and a pickup roller 52 that feeds the recording media P from the paper feed cassette 51 one by one toward the registration roller pair 41. .

(Line head)
Next, the line head 13 will be described.
FIG. 2 is a cross-sectional view of the line head 13 provided in the image forming apparatus 1. FIG. 3 is a perspective view showing the line head 13 provided with the fan portion 66. As shown in FIG. 2, the line head 13 is disposed so as to face the outer peripheral surface (more specifically, the light receiving surface 111) of the photosensitive drum 11, and includes a housing 6, a light emitting substrate unit 7, a circuit. A substrate unit 8, a flexible printed circuit board 9, and a lens array 16 are included.
Here, the light emitting board unit 7 is connected to the circuit board unit 8 via the flexible printed board 9. The light emitting board unit 7, the circuit board unit 8, and the flexible printed board 9 are disposed inside the housing 6.

In the line head 13, the light L emitted from the light emitting substrate unit 7 passes through the lens array 16 and is irradiated onto the light receiving surface 111 of the photosensitive drum 11.
Hereinafter, the details of each part constituting the line head 13 will be described. Hereinafter, for convenience of explanation, the longitudinal direction of the first substrate 71 of the light emitting substrate unit 7 is referred to as a “main scanning direction”, and the width direction is referred to as a “sub scanning direction”.

  The housing 6 has a long shape (longitudinal shape) and is disposed along the axial direction (main scanning direction) of the photosensitive drum 11. As shown in FIG. 2, the housing 6 includes a support member 61 having a substantially U-shaped cross section, and a resin cover member 63 that covers the support member 61 from the lower side in the figure. Has been. The support member 61 and the cover member 63 are joined by a screw or an adhesive. The elongated casing 6 forms a duct 67 that guides air that has flowed into the casing 6 to the outside of the casing 6.

  The support member 61 can be configured using, for example, a resin material to which a filler whose main material is a metal material is added. In this case, even if the support member 61 has a complicated shape, the support member 61 can be molded using an injection molding method or a press molding method. Note that the support member 61 is not limited to a resin material, and may be formed by, for example, bending a metal plate made of iron, stainless steel, an aluminum alloy, or the like.

Further, as shown in FIG. 3, a fan portion 66 is disposed in an opening 67 a at one end of a duct 67 formed by the housing 6. The fan unit 66 rotates the blade member about the central axis, thereby blowing air from the outside of the duct 67 to the opening 67a and exhausting it from the opening 67b at the other end. Thereby, the heated air inside the duct 67 is exhausted from the duct 67 to the outside, and the inside of the duct 67, that is, the housing 6 is cooled.
In the present embodiment, the fan 6 is configured to cool the housing 6 by blowing air outside the duct 67 into the duct 67. However, conversely, the housing 6 may be cooled by sucking the heated air inside the duct 67 from the opening 67a by the fan portion 66.

Returning to FIG. 2, the support member 61 of the housing is formed with an opening 611 that penetrates in the optical axis direction of each light emitting element 72, and the lens array 16 is inside and outside of the support member 61 through the opening 611. It is provided so that it may penetrate. The wall surface of the opening 611 and the lens array 16 are bonded to each other via an adhesive or the like. Thereby, the lens array 16 is supported by the support member 61.
A space 612 is formed between the vicinity of the opening 611 of the support member 61 and the first substrate 71. The space 612 optimizes the distance between the lens array 16 and the first substrate 71. A spacer made of a plate-like resin material or glass material is disposed in the space 612, and the distance between the lens array 16 and the first substrate 71 is adjusted according to the thickness of the spacer. Also good.

The light emitting substrate unit 7 includes a first substrate 71 having a long shape, a plurality of light emitting elements 72 arranged along the longitudinal direction on one surface side of the first substrate 71, and a plurality of light emitting elements 72. The sealing member 73 which covers is provided.
The 1st board | substrate 71 supports each light emitting element 72, and is comprised with the plate-shaped body in which an external shape makes long shape. The first substrate 71 is joined to the upper inner wall surface of the duct 67 formed by the housing 6 via an adhesive or the like.

Here, the first substrate 71 is a glass substrate made of a glass material. A glass substrate has insulation and light transmittance. Therefore, when the first substrate 71 is a glass substrate, an organic electroluminescence element can be formed as the light emitting element 72 on the first substrate 71 relatively easily and inexpensively. Further, by configuring the first substrate 71 with a glass material, heat generated by light emission of each light emitting element 72 can be efficiently radiated to the housing 6 and the like via the first substrate 71.
A plurality of light emitting elements 72 and a sealing member 73 are bonded to one surface (the lower surface in the drawing) of the first substrate 71. The plurality of light emitting elements 72 are arranged on the first substrate 71 along the longitudinal direction (main scanning direction). Each light emitting element 72 is installed so that its optical axis is substantially orthogonal to the plate surface of the first substrate 71.

FIG. 4 is a cross-sectional view showing a schematic configuration of each light emitting element provided in the line head 13. The light emitting element 72 shown in the figure is composed of an organic EL element (organic electroluminescence element).
Specifically, as shown in FIG. 4, each light emitting element 72 includes an anode 722, an organic semiconductor layer 723 provided on the anode 722, and a cathode 724 provided on the organic semiconductor layer 723. These are provided on the first substrate 71.
In this embodiment, the organic semiconductor layer 723 is a stacked layer including a plurality of layers stacked in this order from the anode 722 side to the cathode 724 side in the order of the hole transport layer 726, the light emitting layer 727, and the electron transport layer 728. It is a body.

  In the light emitting element 72, when a DC voltage is applied between the anode 722 and the cathode 724, electrons transported through the electron transport layer 728 and transported through the hole transport layer 726 in the light emitting layer 727. Recombine with the positive holes. Then, excitons (excitons) are generated by the energy released upon recombination, and the energy is released as light L (fluorescence or phosphorescence) when the excitons return to the ground state. Thereby, the light emitting element 72 (light emitting layer 727) emits light.

In the present embodiment, the light emitting element 72 is an element having a bottom emission structure in which the light L from the light emitting layer 727 is extracted and used on the anode 722 side.
The anode 722 is an electrode that injects holes into the organic semiconductor layer 723 (a hole transport layer 726 described later). The constituent material of the anode 722 is not particularly limited, but includes, for example, ITO (Indium Tin Oxide), SnO ₂ , Sb-containing SnO ₂ , oxides such as Al-containing ZnO, Au, Pt, Ag, Cu or the like. An alloy etc. are mentioned, At least 1 sort (s) of these can be used.

The cathode 724 is an electrode that injects electrons into the organic semiconductor layer 723 (an electron transport layer 728 described later). The cathode 724 also has a function as a reflective film that reflects the light L leaked to the cathode 724 side to the anode 722 side. Thereby, more light quantity of the light L which goes to the lens array 16 side can be ensured.
Examples of the constituent material of the cathode 724 include Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, Al, Cs, Rb, and alloys containing these. At least one of them can be used.

An organic semiconductor layer 723 is provided between the anode 722 and the cathode 724. As described above, the organic semiconductor layer 723 includes the hole transport layer 726, the light emitting layer 727, and the electron transport layer 728, which are stacked on the anode 722 in this order.
The hole transport layer 726 has a function of transporting holes injected from the anode 722 to the light emitting layer 727.
The constituent material (hole transport material) of the hole transport layer 726 may be any material as long as it has a hole transport capability, but is preferably a conjugated compound. A conjugated compound is particularly excellent in hole transport capability because it can transport holes very smoothly due to the property of its unique electron cloud spread.

  Examples of the hole transport material include arylcycloalkane compounds such as 1,1-bis (4-di-para-triaminophenyl) cyclohexane, 4,4 ′, 4 ″ -trimethyltriphenylamine Arylamine compounds such as N, N, N ′, N′-tetraphenyl-para-phenylenediamine, phenylenediamine compounds such as triazole, triazole compounds such as triazole, imidazole compounds such as imidazole, 1 Oxadiazole compounds such as 1,3,4-oxadiazole, anthracene compounds such as anthracene, fluorenone compounds such as fluorenone, aniline compounds such as polyaniline, phthalocyanine compounds such as phthalocyanine, etc. One or two or more of these It can be used in conjunction.

The electron transport layer 728 has a function of transporting electrons injected from the cathode 724 to the light emitting layer 727.
As a constituent material (electron transport material) of the electron transport layer 728, for example, 1,3,5-tris [(3-phenyl-6-tri-fluoromethyl) quinoxalin-2-yl] benzene (TPQ1) is used. Benzene compounds (starburst compounds), naphthalene compounds such as naphthalene, phenanthrene compounds such as phenanthrene, chrysene compounds such as chrysene, perylene compounds such as perylene, anthracene compounds such as anthracene, An oxadiazole-based compound such as oxadiazole, a triazole-based compound such as triazole, and the like can be given, and one or more of these can be used in combination.
The light-emitting layer 727 is formed of a constituent material that can inject holes from the anode 722 side when a voltage is applied and electrons from the cathode 724 side and can provide a field where holes and electrons recombine. Any one can be used.

As a constituent material (light-emitting material) of the light-emitting layer 727, 1,3,5-tris [(3-phenyl-6-tri-fluoromethyl) quinoxalin-2-yl] benzene (TPQ1), 1,3,5- Benzene compounds such as tris [{3- (4-t-butylphenyl) -6-trisfluoromethyl} quinoxalin-2-yl] benzene (TPQ2), such as phthalocyanine, copper phthalocyanine (CuPc), iron phthalocyanine Low molecular weight compounds such as metal or metal-free phthalocyanine compounds, tris (8-hydroxyquinolinolate) aluminum (Alq3), factory (2-phenylpyridine) iridium (Ir (ppy) ₃ ), and oxa Polymers such as diazole polymers, triazole polymers, carbazole polymers , A combination of one or more of these, it is possible to obtain the light L with luminescent color of interest.

In the present embodiment, each of the light emitting elements 72 is configured to emit red light.
Here, examples of the light-emitting layer 727 that emits red light include (4-dicyanomethylene) -2-methyl-6- (paradimethylaminostyryl) -4H-pyran (DCM), Nile red, and the like. Each light emitting element 72 is not limited to be configured to emit red light, and may be configured to emit monochromatic light of other colors or white light. Thus, in the organic EL element, the light L emitted from the light emitting layer 727 can be appropriately set to monochromatic light of an arbitrary color according to the constituent material of the light emitting layer 727.

However, the spectral sensitivity characteristics of a photosensitive drum (photoconductor) generally used in an electrophotographic process is set to have a peak in the region from red to the near infrared, which is the emission wavelength of a semiconductor laser. It is preferable to use a red light emitting material.
When each light emitting element 72 is comprised by such an organic EL element (organic electroluminescent element), the space | interval (pitch) between light emitting elements 72 can be set comparatively small. Thereby, when an image is recorded on the recording medium P, the recording density on the recording medium P becomes relatively high. Therefore, the recording medium P carrying a clearer image can be obtained.

  In addition, when each light emitting element 72 is configured by an organic EL element, the longitudinal direction of the first substrate 71 (with the number of light emitting elements 72 in the width direction (sub-scanning direction) of the first substrate 71 being suppressed. The arrangement density of the light emitting elements 72 in the main scanning direction) can be increased. Further, when forming the light emitting element 72, TFTs, wirings, and the like constituting a part of a drive circuit for driving the light emitting element 72 are formed on the first substrate 71 together with the light emitting element 72. Can do. As a result, the line head 13 can be made cheaper while suppressing the width of the first substrate 71.

An optical path adjusting member such as a reflector for preventing the light L from spreading may be provided on the outer peripheral side of each light emitting element 72.
The light emitting element 72 is not limited to an element having a bottom emission structure, and may be an element having a top emission structure in which light L from the light emitting layer 727 is extracted and used on the cathode 724 side. In this case, the light emitting substrate unit 7 is installed so that the first substrate 71 side is on the lower side.

  Further, the materials or layer configurations of the organic EL elements described above are representative examples, and the effects and advantages of the present invention can be obtained in the same manner even with other materials and layer configurations.

  As shown in FIG. 2, the sealing member 73 provided on the one surface side of the first substrate 71 together with each of the light emitting elements 72 is formed with a recess 731, and the peripheral portion of the recess 731 is an adhesive. For example, the first substrate 71 is joined. A plurality of light emitting elements 72 are accommodated in the recess 731. Thereby, the sealing member 73 covers the plurality of light emitting elements 72.

The sealing member 73 has a gas barrier property, and the sealing member 73 and the first substrate 71 are airtightly joined. Thereby, each part which comprises each light emitting element 72 can be interrupted | blocked from atmospheric gas containing a water | moisture content, oxygen, etc., and the oxidation and deterioration of the said each part can be prevented. Further, it is possible to prevent foreign matter from adhering to each light emitting element 72 and the like.
It is preferable that a desiccant and / or an oxygen scavenger is provided in the recess 731 of the sealing member 73. Thereby, oxidation and deterioration of each part which comprises each light emitting element 72 can be prevented more reliably.

Any desiccant can be used without particular limitation as long as it exhibits a hygroscopic effect in the recess 731. For example, sodium oxide (Na ₂ O), potassium oxide (K ₂ O) can be used. ), Calcium oxide (CaO), barium oxide (BaO), magnesium oxide (MgO), lithium sulfate (Li ₂ SO ₄ ), sodium sulfate (Na ₂ SO ₄ ), calcium sulfate (CaSO ₄ ), magnesium sulfate (MgSO ₄₎ ), Cobalt sulfate (CoSO ₄ ), gallium sulfate (Ga ₂ (SO ₄ ) ₃ ), titanium sulfate (Ti (SO ₄ ) ₂ ), nickel sulfate (NiSO 4), calcium chloride (CaCl 2), magnesium chloride (MgCl ₂ ) , strontium chloride (SrCl _2), yttrium chloride (YCl _3), copper chloride (CuCl _2), cesium fluoride (CsF , Tantalum fluoride (TaF _5), niobium fluoride (NbF _5), calcium bromide (CaBr _2), cerium bromide (CeBr _3), bromide selenium (SEBR _4), vanadium bromide (VBr _2), odor magnesium reduction (MgBr _2), barium iodide (BaI _2), magnesium iodide (MgI _2), barium perchlorate _{(Ba (ClO 4) 2)} , magnesium perchlorate (Mg (ClO _{4) 2)} etc. Can be mentioned.

Examples of the oxygen scavenger include activated carbon, silica gel, activated alumina, molecular sieve, magnesium oxide, iron oxide, and titanium oxide.
Further, the sealing member 73 has a flat surface on the side opposite to the recess 731. Thereby, the 1st board | substrate 71 and the housing | casing 6 can be simply and stably joined via the sealing member 73. FIG.

  The constituent material of the sealing member 73 is not particularly limited, and is a metal material such as stainless steel, aluminum or an alloy thereof, a glass material such as soda lime glass or silicate glass, or a resin material such as acrylic resin or styrene resin. Etc. can be used, but a glass material is preferably used. By configuring both the sealing member 73 and the first substrate 71 with a glass material, it is possible to prevent problems such as deformation and damage due to a difference in linear expansion coefficient between them.

The lens array 16 is bonded to the other surface (the upper surface in the drawing) of the first substrate 71 via a space 612.
The lens array 16 is provided on the light L emission side of the light emitting substrate unit 7. This lens array 16 has a large number of gradient index rod lenses 161 arranged so as to be stacked in two rows in the main scanning direction.
Each rod lens 161 is installed such that its optical axis is in the thickness direction of the first substrate 71. Each rod lens 161 is made of, for example, a light-transmissive resin material and / or glass material.

The circuit board unit 8 includes a second board 81 and a control circuit 822 that is a second circuit unit provided on the second board 81.
The 2nd board | substrate 81 is installed so that the plate | board surface may follow the optical axis of each light emitting element 72 mentioned above. That is, the plate surface of the second substrate 81 is installed so as to be perpendicular or substantially perpendicular to the plate surface of the first substrate 71 described above. In particular, in the present embodiment, the second substrate 81 is installed so as to be inside the outer periphery of the first substrate 71 when the first substrate 71 is viewed in plan.

  Therefore, the second substrate 81 affects the width of the line head 13 even if the width of the second substrate 81 is increased due to an increase in the number of elements and circuits mounted on the second substrate 81. It can be installed so that there is no. Accordingly, at least a part of the drive circuit for driving each light emitting element 72 described above can be mounted on the second substrate 81 without being mounted on the first substrate 71. As a result, the number of elements and circuits mounted on the first substrate 71 can be minimized, and as a result, the width of the first substrate 71 described above can be reduced. Therefore, the line head 13 has a narrow width, and the image forming apparatus 1 can be made small and inexpensive.

  The constituent material of the second substrate 81 can be the same as the constituent material of the first substrate 71 described above, but a mixed material of a glass material and a resin material (for example, a glass, an epoxy resin, and a mixed material). ) Is preferably used. That is, the second substrate 81 is preferably a printed circuit board. Thereby, elements and circuits necessary for driving each light emitting element 72 can be easily and inexpensively mounted on the second substrate 81. Further, the mechanical strength of the second substrate 81 can be made excellent, and as a result, the second substrate 81 is prevented from being damaged when the circuit board unit 8 is connected to a printer controller 18 described later. be able to.

  On the second substrate 81, a control circuit 822 (second circuit unit) of the circuit unit 82 described later is provided. FIG. 5 is a diagram showing the configuration of the control system of the line head 13. As shown in the figure, the line head 13 has a circuit unit 82. The circuit unit 82 includes a drive circuit 821 for driving each light emitting element 72 and a control circuit 822 for controlling the operation of the drive circuit 821.

The drive circuit 821 is for driving each light emitting element 72 described above. In this embodiment, the drive circuit 821 includes a plurality of gate voltage holding type constant current drive circuits 83, a selection switch 84, and a driver IC 85.
Each constant current drive circuit 83 includes a constant current transistor 831, a voltage holding capacitor 832, and a selection transistor 833.

  In each constant current drive circuit 83, when the selection transistor 833 is turned on, a constant current according to an output voltage of a driver IC 85 described later flows to the light emitting element 72 through the constant current transistor 831, and the light emitting element 72 emits light. In addition, since the output voltage of the driver IC 85 is held in the voltage holding capacitor 832, even if the selection transistor 833 is turned off, current continues to flow through the light emitting element 72, and light emission of the light emitting element 72 is maintained.

The selection switch 84 is switched by a Select signal from the control circuit 822, and selects the constant current drive circuit 83 for each predetermined block. By switching the selection switch 84, it is possible to set a voltage for energizing each light emitting element 72 for each predetermined block.
The driver IC 85 includes a shift register 851, a latch circuit 852, and a DAC 853 (D / A converter).

  In the driver IC 85, a data signal (DATA) synchronized with the clock signal (CLK) is sent from the control circuit 822 to the shift register 851 using the Start pulse signal (Start) as a trigger. On the other hand, a latch signal (Latch) is sent from the control circuit 822 to the latch circuit 852, and the data signal is latched by the shift register 851 so that the data signals are aligned at a predetermined timing. The data signals (digital signals) are sent to the DAC 853 in a state where they are aligned at a predetermined timing, and the DAC 853 outputs a predetermined voltage signal (analog signal) to the constant current driving circuit 83 (selection transistor 833) described above.

  The drive circuit 821 described above is an active drive circuit, but instead of the drive circuit 821, for example, a passive drive circuit 821A as shown in FIG. 6 may be used. In this drive circuit 821A, a constant current type driver IC 85A is used, and the selection switch 84A is switched by a Select signal from the control circuit 822, and selects the light emitting element 72 for each predetermined block.

Here, the plurality of light emitting elements 72, the plurality of constant current drive circuits 83, the selection switch 84, and the driver IC 85 described above are provided on the first substrate 71 described above, and constitute a first circuit unit. .
The drive circuit 821 as described above is controlled by the control circuit 822. The control circuit 822 controls the operation of the drive circuit 821. The control circuit 822 controls the operation of the drive circuit 821 based on a signal from the printer controller 18 described later. Here, the control circuit 822 is provided on the above-described second substrate 81 and constitutes a second circuit unit.

The control circuit 822 includes an interface circuit 86, a plurality (two in this embodiment) of data control circuits 87, and a correction value memory 88.
The interface circuit 86 receives a signal from the printer controller 18 provided in the main body of the image forming apparatus 1 (outside of the line head 13). In the present embodiment, as shown in FIG. 5, the interface circuit 86 is configured by a receiving circuit using LVDS (Low voltage differential signaling), and is developed from the printer controller 18 to the data line together with the timing clock. Data is received and distributed to each data control circuit 87.
The data control circuit 87 corrects the data from the interface circuit 86 based on the correction data in the correction value memory 88 so that the light emission amount of each light emitting element 72 is optimized, and the corrected data is described above together with the control signal. The data is sent to the driver IC 85 (shift register 851).

  The printer controller 18 has a function of transmitting a signal for driving control of each light emitting element 72 to the control circuit 822. In the present embodiment, the printer controller 18 includes a head controller 181 for controlling the driving of the line head 13 and a transmission circuit 182 for transmitting a signal from the head controller 181 to the interface circuit 86 described above. ing. The printer controller 18 also has a function of controlling each unit of the image forming apparatus 1.

  Since the control circuit 822 is provided on the second substrate 81 described above, the control circuit 822 is installed so as to be covered by the casing 6 described above. That is, the housing 6 is disposed so as to cover the control circuit 822. Accordingly, it is possible to prevent an adverse electromagnetic effect such as noise from being mixed in from the wiring between each light emitting element 72 and the control circuit 822, and to perform highly accurate exposure processing stably. Further, by providing the circuit unit 82 inside the housing 6, the length of the wiring between each light emitting element 72 and the circuit unit 82 can be shortened. Therefore, also in this respect, it is possible to effectively prevent noise from being mixed in from the wiring between each light emitting element 72 and the circuit unit 82.

The drive of each light emitting element 72 is controlled by such a control system (circuit unit 82). The configuration of the control system described above is an example, and the present invention is not limited to this.
Such a circuit portion 82 is electrically connected to each light emitting element 72. The flexible printed board 9 includes wiring for electrically connecting the light emitting board unit 7 and the circuit board unit 8 described above.

  In this embodiment, the flexible printed circuit board 9 is comprised by the some flexible printed circuit board (FPC). Thereby, the freedom degree of the installation of the 2nd board | substrate 81 with respect to the 1st board | substrate 71 can be raised, As a result, the board surface of the 2nd board | substrate 81 is the board surface of the 1st board | substrate 71 as mentioned above. It can install so that it may become perpendicular | vertical to. The flexible printed circuit board 9 may be composed of a single flexible printed circuit board (FPC).

  As shown in FIG. 2, the flexible printed circuit board 9 is fixed to one end of each of the first substrate 71 and the second substrate 81 in the width direction. That is, the flexible printed circuit board 9 is provided so as to connect the end portions in the width direction of the first substrate 71 and the second substrate 81. Thereby, the dimension in the longitudinal direction of the line head 13 can be shortened (lengthening is prevented). By using such a line head 13, it is possible to reduce the size of the image forming apparatus 1 (the size in the main scanning direction).

In the line head 13 in the image forming apparatus according to the present embodiment, the long casing 6 of the line head 13 forms a duct 67 that guides the air flowing into the casing 6 to the outside of the casing 6. Yes. A fan portion 66 is disposed in the opening 67 a of the duct 67.
Thus, by blowing air from the fan portion 66 to the inside of the duct 67 and exhausting it to the outside, heat generated in the light emitting board unit 7 and the like disposed inside the duct 67 can be radiated to the outside, and the line head 13 can be efficiently cooled. As a result, it is possible to prevent the housing 6 from being distorted due to heat generation inside the housing 6 of the line head 13, and to suppress the occurrence of image defects due to deformation of the housing 6 or the like.

(Second Embodiment)
Next, an image forming apparatus according to the second embodiment will be described.

The image forming apparatus according to the second embodiment differs from the image forming apparatus according to the first embodiment described above in the configuration of the line head.
FIG. 7 is a cross-sectional view of the line head 13A in the second embodiment. Hereinafter, the line head 13A of the second embodiment will be described focusing on the differences from the line head 13 of the first embodiment described above.

In the line head 13 in the first embodiment described above, the driver IC 85 of the drive circuit 821 shown in FIG. 5 is provided on the first substrate 71.
However, in the line head 13A in the second embodiment, as shown in FIG. 7, a driver IC 85 is provided on the flexible printed circuit board 9 as a semiconductor element. Further, the driver IC 85 provided on the flexible printed board 9 is disposed so as to be in contact with the inner wall surface on the left side of the duct 67 formed in the housing 6 in the drawing.

In the present embodiment, by providing the driver IC 85 on the flexible printed board 9, many wirings from the light emitting board unit 7 can be integrated on the flexible printed board 9.
As a result, the number of terminals and the number of wires necessary for connection between the flexible printed circuit board 9 and the circuit board unit 8 can be reduced, and the line head itself can be reduced in size.

Further, the driver IC 85 is disposed so as to contact the inner wall surface of the duct 67 formed by the housing 6.
Thereby, the heat generated by the driver IC 85 can be radiated from the housing 6 to the outside. As a result, the driver IC 85 can be prevented from malfunctioning or malfunctioning due to heat, and the reliability of the line head 13A can be improved.

(Third embodiment)
Next, an image forming apparatus according to the third embodiment will be described.

The image forming apparatus according to the third embodiment is different from the image forming apparatus according to the first embodiment described above in the configuration of the line head.
FIG. 8 is a cross-sectional view of the line head 13B in the third embodiment. Hereinafter, the line head 13B of the third embodiment will be described focusing on the differences from the line head 13 of the first embodiment described above.

In the line head 13 in the first embodiment described above, the driver IC 85 in the drive circuit 821 shown in FIG. 5 is provided on the first substrate 71.
However, in the line head 13B in the third embodiment, as shown in FIG. 8, the driver IC 85 is provided on the circuit board unit 8 as a semiconductor element. Further, the driver IC 85 provided on the circuit board unit 8 is disposed so as to be in contact with the inner wall surface on the left side of the duct 67 formed by the housing 6 in the drawing.

  In the present embodiment, by providing the driver IC 85 on the circuit board unit 8, the TFT circuit on the first substrate 71 can be simplified, and the cost of the line head can be reduced.

Further, the driver IC 85 is disposed so as to contact the inner wall surface of the duct 67 formed by the housing 6.
Thereby, the heat generated by the driver IC 85 can be radiated from the housing 6 to the outside. As a result, the driver IC 85 can be prevented from malfunctioning or malfunctioning due to heat, and the reliability of the line head 13B can be improved.

(Fourth embodiment)
Next, an image forming apparatus according to the fourth embodiment will be described.

The image forming apparatus according to the fourth embodiment differs from the image forming apparatus according to the first embodiment described above in the configuration around the line head.
FIG. 9 is a perspective view of the periphery of the line head 13C provided in each of the image forming stations 10Y, 10M, 10C, and 10K in the fourth embodiment. Hereinafter, the image forming apparatus according to the fourth embodiment will be described focusing on differences from the image forming apparatus according to the first embodiment described above.

In the line head 13 in the first embodiment described above, the fan portion 66 is disposed in the opening 67 a of the duct 67 formed by the housing 6.
However, in the line head 13C according to the fourth embodiment, as shown in FIG. 9, the fan section 66 is disposed on the photoconductor cover 115 in each of the image forming stations 10Y, 10M, 10C, and 10K. The fan portion 66 disposed on the photoconductor cover 115 is located at a position facing the opening 67a of the duct 67, and can blow air from the outside of the duct 67 to the opening 67a and exhaust it from the opening 67b. .

Thereby, the heated air inside the duct 67 is exhausted to the outside, the inside of the duct 67, that is, the housing 6 is cooled, and the line head 13C can be efficiently cooled.
Further, since the fan portion 66 is not directly disposed in the opening 67a of the duct 67, the line head 13C can be easily disposed in each of the image forming stations 10Y, 10M, 10C, and 10K. Maintenance is also improved.
The fan head 66 may cool the line head 13 </ b> C by sucking the heat generated in the duct 67 from the opening 67 a.

(Fifth embodiment)
Next, an image forming apparatus according to a fifth embodiment will be described.

The image forming apparatus according to the fifth embodiment and the image forming apparatus according to the first embodiment described above are different in the configuration around the line head.
FIG. 10 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to the fifth embodiment. Hereinafter, the image forming apparatus according to the fifth embodiment will be described focusing on differences from the image forming apparatus according to the first embodiment described above.

  In the line head 13 in the first embodiment described above, the fan portion 66 is disposed in the opening 67 a of the duct 67 formed by the housing 6. However, in the line head 13D in the fifth embodiment, the fan portion 66 is not disposed in the opening 67a of the duct 67, as in the line head 13C in the fourth embodiment described above.

In the image forming apparatus 1D according to the fifth embodiment, as shown in FIG. 10, a fan unit 68 and a duct 69 as a second duct are arranged with respect to the image forming apparatus 1 according to the first embodiment. ing. An opening 69a at one end of the duct 69 opens to the outside of the image forming apparatus 1D, and the fan portion 68 is disposed in the vicinity of the opening 69a.
In addition, four openings 69 b are formed at the other end of the duct 69. Each opening 69b is connected to the opening 67a of the duct 67 of each line head 13D in the image forming stations 10Y, 10M, 10C, and 10K. That is, the duct 67 of each line head 13D communicates with the outside of the image forming apparatus 1D via the duct 69.
The fan unit 68 rotates the blade member about the central axis, thereby sucking the air in the duct 67 of each line head 13D through the duct 69 and exhausting it outside the image forming apparatus 1D.

Thereby, the heated air inside the duct 67 is exhausted to the outside of the image forming apparatus 1D, the inside of the duct 67, that is, the housing 6 is cooled, and the line head 13D can be efficiently cooled.
Note that the fan unit 68 cools the line head 13D by blowing air from the outside of the image forming apparatus 1D to the opening 67a of the duct 67 through the duct 69 and exhausting it from the opening 67b. Also good.

As described above, the line head and the image forming apparatus have been described in the above-described embodiment. However, the present invention is not limited to this, and each unit constituting the line head and the image forming apparatus has an arbitrary configuration that can exhibit the same function. Can be substituted for Moreover, arbitrary components may be added.
Moreover, each light emitting element is not limited to the structure by an organic EL element, respectively, For example, you may be comprised by the light emitting diode (LED).

  DESCRIPTION OF SYMBOLS 1,1D ... Image forming apparatus, 6 ... Housing, 7 ... Light emitting board unit, 8 ... Circuit board unit, 9 ... Flexible printed circuit board, 10 ... Image forming unit, 11 ... Photosensitive drum, 12 ... Charging unit, 13, 13A , 13B, 13C, 13D ... line head, 14 ... developing device, 15 ... cleaning unit, 16 ... lens array, 20 ... transfer unit, 21 ... intermediate transfer belt, 22 ... primary transfer roller, 23 ... drive roller, 24 ... driven Roller, 25 ... secondary transfer roller, 26 ... cleaning unit, 30 ... fixing unit, 40 ... transport mechanism, 41 ... registration roller pair, 42, 43, 44 ... transport roller pair, 50 ... paper feed unit, 51 ... paper feed Cassette, 52 ... pickup roller, 61 ... support member, 63 ... cover member, 66, 68 ... fan section, 6 , 69 ... Duct, 67a, 67b, 69a, 69b ... Duct opening, 71 ... First substrate, 72 ... Light emitting element, 73 ... Sealing member, 81 ... Second substrate, 85 ... Driver IC, 111 ... Light receiving surface 115... Photoconductor cover 151, 261 Cleaning blade 161 161 Rod roller 301 Fixing roller 302 Pressure roller 611 Opening 612 Space 822 Control circuit

Claims (7)

A housing,
A light-emitting substrate unit including a first substrate and a light-emitting element provided on the first substrate;
A circuit board unit including an interface circuit disposed inside the housing and receiving a second board and a signal provided on the second board to drive the light emitting element;
A flexible printed circuit board including wiring for electrically connecting the light emitting board unit and the circuit board unit;
The line head according to claim 1, wherein the casing forms a duct for guiding the air flowing into the casing to the outside of the casing.   The line according to claim 1, wherein a semiconductor element in which at least a part of a drive circuit for driving the light emitting element is formed is disposed on the circuit board unit, and the semiconductor element is disposed in contact with the housing. head.   The line according to claim 1, wherein a semiconductor element in which at least a part of a drive circuit for driving the light emitting element is formed is disposed on the flexible printed circuit board, and the semiconductor element is disposed in contact with the housing. head.   The line head according to any one of claims 1 to 3, further comprising a fan unit that generates an air flow in the duct. A latent image carrier;
A line head for exposing the latent image carrier,
The line head is
A housing,
A light-emitting substrate unit including a first substrate and a light-emitting element provided on the first substrate;
A circuit board unit including an interface circuit disposed inside the housing and receiving a second board and a signal provided on the second board to drive the light emitting element;
A flexible printed circuit board including wiring for electrically connecting the light emitting board unit and the circuit board unit;
The image forming apparatus, wherein the casing forms a duct that guides air flowing into the casing to the outside of the casing.   The image forming apparatus according to claim 5, further comprising a fan unit that generates an air flow in the duct at a position facing an opening of the duct formed by the housing. A second duct communicating with an opening of the duct formed by the housing;
The image forming apparatus according to claim 5, further comprising: a fan unit that generates an air flow in a duct formed by the housing through the second duct.

Images