JP2010194717A - Line head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line head which is excellent in assembling properties and can realize a light exposure processing with high accuracy, and to provide an image forming apparatus capable of obtaining an image with a low cost and a high quality. <P>SOLUTION: The line head 13 includes: a substrate 71 with light transmission properties; a plurality of light emitting elements 72 arranged in a first direction on one face side of the substrate 71; a lens array 16 connected to the other face of the substrate 71 through a plate-like spacer 17 with light transmission properties, and imaging the light from the light emitting element 72; and a support member 6 provided so as to cover the spacer 17 from the opposite side to the substrate 71 side. The width of the spacer 17 in a second direction perpendicular or approximately perpendicular to the first direction is at least the width of the substrate 71 in the second direction, and the end in the second direction of the substrate 71 is not projected to the outside more than the end in the second direction of the spacer 17. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 using an electrophotographic system are provided with exposure means for forming an electrostatic latent image by exposing the outer surface of a cylindrical photoconductor. As such an exposure means, a line head having a structure in which a plurality of light emitting elements are arranged in the axial direction (main scanning direction) of a photoreceptor is known (for example, see Patent Document 1).
For example, in the line head disclosed in Patent Document 1, a plurality of bottom emission type organic EL elements are provided as light emitting elements on one surface of a glass substrate, and light-transmissive refraction is provided on the other surface of the glass substrate. An SL array (lens array) is provided via the rate layer. The glass substrate, the organic EL element, and the refractive index layer are housed in a head case, and the SL array is disposed in an opening formed in the head case.

In such a line head, light from the organic EL element passes through the glass substrate and the refractive index layer and is condensed (imaged) by the SL array, but the refractive index layer interposed between the SL array and the glass substrate. By increasing the refractive index of the light from the refractive index of air, the amount of light taken from the organic EL element to the SL array can be increased.
Further, in such a line head, since the refractive index layer is covered with a light-shielding head case, it is possible to prevent light that has not entered the SL array from the organic EL element from leaking to the outside. As a result, exposure of the photoreceptor with unnecessary light can be prevented.

  However, in the line head according to Patent Document 1, the width of the glass substrate is larger than the width of the refractive index layer, and the end in the width direction of the glass substrate protrudes from the end of the refractive index layer. The mechanical strength will be low. For this reason, when the glass substrate or the like is installed in the head case (when assembled), chipping or cracking of the protruding portion of the glass substrate may occur.

JP 2006-205384 A

  An object of the present invention is to provide a line head that is excellent in assemblability and can realize high-precision exposure processing, and to provide an image forming apparatus that can obtain a high-quality image.

Such an object is achieved by the present invention described below.
The line head of the present invention includes a substrate having optical transparency,
A light emitting device disposed in a first direction on one side of the substrate;
A spacer bonded to the other surface opposite to the one surface of the substrate and having light transmittance;
An imaging optical system that is bonded to a surface of the spacer facing the substrate-side surface and forms an image of light from the light-emitting element;
The spacer is provided so as to cover a surface facing the surface on the substrate side, and includes a light-shielding support member that includes the opening through which the imaging optical system is inserted and supports the substrate.
A width of the spacer in a second direction perpendicular to the first direction is equal to or greater than a width of the substrate in the second direction;
One end of the substrate in the second direction is configured not to protrude outward from the one end of the spacer in the second direction.

In the line head according to the aspect of the invention, it is preferable that the line head includes a wiring portion provided so as to be drawn out from the one surface of the substrate in the second direction.
In the line head according to the aspect of the invention, it is preferable that the cover member is in close contact with a surface of the spacer opposite to the surface on the substrate side.
In the line head according to the aspect of the invention, it is preferable that the cover member is in close contact with a side surface perpendicular or substantially perpendicular to the one surface of the spacer.

The image forming apparatus of the present invention includes a latent image carrier on which a latent image is formed,
A line head for exposing the latent image carrier,
The line head is
A substrate having optical transparency;
A light emitting device disposed in a first direction on one side of the substrate;
A spacer bonded to the other surface opposite to the one surface of the substrate and having light transmittance;
An imaging optical system that is bonded to a surface of the spacer facing the substrate-side surface and forms an image of light from the light-emitting element;
The spacer is provided so as to cover a surface facing the surface on the substrate side, and includes a light-shielding support member that includes the opening through which the imaging optical system is inserted and supports the substrate.
A width of the spacer in a second direction perpendicular to the first direction is equal to or greater than a width of the substrate in the second direction;
One end of the substrate in the second direction is configured not to protrude outward from the one end of the spacer in the second direction.

  According to the line head of the present invention having the above-described configuration, it is possible to realize an exposure process with excellent assemblability, a narrow width, and high accuracy. Further, according to the image forming apparatus of the present invention, an inexpensive and high-quality image can be obtained.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of a line head provided in the image forming apparatus shown in FIG. It is sectional drawing which shows schematic structure of the light emitting element with which the line head shown in FIG. 2 was equipped. It is a figure which shows the structure of the control system of the line head shown in FIG. It is a figure for demonstrating the modification of the control system shown in FIG. It is a cross-sectional view of a line head according to a second embodiment of the present invention.

Hereinafter, a line head and an image forming apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<First Embodiment>
FIG. 1 is a schematic diagram showing the overall configuration of the image forming apparatus according to the first embodiment of the present invention, FIG. 2 is a transverse sectional view of a line head provided in the image forming apparatus shown in FIG. 1, and FIG. 2 is a cross-sectional view showing a schematic configuration of a light emitting element provided in the line head shown in FIG. 2, FIG. 4 is a diagram showing a configuration of a control system of the line head shown in FIG. 2, and FIG. 5 is a diagram of the control system shown in FIG. It is a figure for demonstrating a modification. In the following, for convenience of explanation, the upper side in FIGS. 1 to 3 is referred to as “upper” and the lower side is referred to as “lower”.

(Image forming device)
An image forming apparatus 1 shown in FIG. 1 is an electrophotographic printer that records an image on a recording medium P through a series of image forming processes including a charging process, an exposure process, a developing process, a transfer process, and a fixing process. In the present embodiment, the image forming apparatus 1 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, and a fixing unit for a fixing process. 30, a transport mechanism 40 for transporting a recording medium P such as paper, and a paper feed unit 50 that supplies the recording medium P to the transport mechanism 40.

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 an image forming station 10K to be formed are provided.
Each of the image forming stations 10Y, 10C, 10M, and 10K includes a photosensitive drum (photosensitive member) 11 that is a latent image carrier that carries an electrostatic latent image, and a charging unit is disposed around (outer peripheral side). 12, a line head (exposure unit) 13, a developing device 14, and a cleaning unit 15 are disposed. Here, the image forming stations 10Y, 10C, 10M, and 10K have substantially the same configuration except that the color of the toner used is different.

The photosensitive drum 11 has a cylindrical shape as a whole, and can rotate around the axis in the direction of the arrow 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 that receives light L (emitted light) from the line head 13 (see FIG. 2).
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 in response to the image information. When the light L is irradiated on the light receiving surface 111 of the uniformly charged photosensitive drum 11, a latent image (electrostatic latent image) corresponding to the irradiation pattern of the light L is formed on the light receiving surface 111. The configuration of the line head 13 will be described in detail 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 has a rubber cleaning blade 151 that abuts on the light receiving surface 111 of the photosensitive drum 11, so that the toner remaining on the photosensitive drum 11 after the primary transfer described later is scraped off and removed by the cleaning blade 151. It has become.

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 as described above to the recording medium P.
In each of the image forming stations 10Y, 10C, 10M, 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 a toner image to the intermediate transfer belt 21 by a primary transfer roller 22 described later, 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 shown in FIG. 1) primary transfer rollers 22, drive rollers 23, and driven rollers 24. It is stretched, and is driven to rotate in the direction of the arrow shown in FIG.
Each primary transfer roller 22 is disposed opposite to the corresponding photosensitive drum 11 via an intermediate transfer belt 21 so that a single color toner image on the photosensitive drum 11 is transferred (primary transfer) to the intermediate transfer belt 21. It has become. At the time of primary transfer, the primary transfer roller 22 is applied with a primary transfer voltage (primary transfer bias) having a polarity opposite to the charging polarity of the toner.

On the intermediate transfer belt 21, a toner image of at least one of yellow, magenta, cyan, and black is carried. 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. During such secondary transfer, the drive roller 23 also functions as a backup roller for the secondary transfer roller 25.

The cleaning unit 26 has a rubber cleaning blade 261 that contacts the surface of the intermediate transfer belt 21, and the toner remaining on the intermediate transfer belt 21 after the secondary transfer is scraped off and removed by the cleaning blade 261. It has become.
The fixing unit 30 includes a fixing roller 301 and a pressure roller 302 that is pressed against the fixing roller 301, and is configured such that the recording medium P passes between the fixing roller 301 and the pressure roller 302. Yes. 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 having such a configuration, the recording medium P that has received 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 transferred. It is fused to 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 while feeding the recording medium P to the secondary transfer portion between the secondary transfer roller 25 and the intermediate transfer belt 21 described above, and fixing by the fixing unit 30. Conveying roller pairs 42, 43, and 44 for nipping and conveying the processed recording medium P are provided.
When such a transport mechanism 40 forms an image on only 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. Then, it is discharged outside the image forming apparatus 1. When forming an image on both surfaces of the recording medium P, the recording medium P fixed on one surface by the fixing unit 30 is once sandwiched by the conveying roller pair 42 and then the conveying roller pair 42 is driven to reverse. Then, the pair of conveying rollers 43 and 44 are driven, 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 feeding unit 50 includes a paper feeding cassette 51 that stores unused recording media P, and a pickup roller 52 that feeds the recording media P from the paper feeding cassette 51 to the registration roller pair 41 one by one. .

(Line head)
Next, the line head 13 will be described.
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 (see FIGS. 1 and 2).
As shown in FIG. 2, the line head 13 includes a support member 6 and a light emitting substrate unit 7. Although not shown, the light emitting substrate unit 7 is driven by a light emitting element 72 as will be described later. A control board for controlling the circuit to be connected is connected.
In such a line head 13, the light L emitted from the light emitting substrate unit 7 passes through the spacer 17 and the lens array 16 and is irradiated onto the light receiving surface 111 of the photosensitive drum 11.

Hereinafter, each part which comprises the line head 13 is demonstrated in detail sequentially. Hereinafter, for convenience of explanation, the longitudinal direction (first direction) of the substrate 71 of the light emitting substrate unit 7 is referred to as “main scanning direction”, and the width direction (second direction) is referred to as “sub-scanning direction”.
The support member 6 has a long shape (longitudinal shape) and is installed along the axial direction (main scanning direction) of the photosensitive drum 11.
As shown in FIG. 2, the support member 6 includes a substrate mounting portion 61 and a pair of leg portions 62, and the cross-sectional shape of the support member 6 is substantially U-shaped.

The substrate mounting portion 61 is provided along the plate surface of the substrate 71 in a cross section shown in FIG. 2 (a cross section perpendicular to the longitudinal direction of the substrate 71 described later).
The substrate mounting portion 61 has a long plate shape, and a substrate 71 of a light emitting substrate unit 7 to be described later is mounted on one surface side (lower side in FIG. 2). The substrate mounting unit 61 fixes and supports the substrate 71 via spacers 17 described later.
Further, the substrate mounting portion 61 is formed with an opening 611 that penetrates in the optical axis direction of each light emitting element 72, and the lens array 16 penetrates the inside and outside of the support member 6 through the opening 611. Is provided.

The pair of leg portions 62 extends from both ends of the substrate mounting portion 61 in the width direction (sub-scanning direction) to the substrate 71 side. That is, the pair of leg portions 62 extends downward from both end portions in the width direction of the substrate mounting portion 61 (that is, both end portions in the short direction). Thus, the light emitting substrate unit 7 is provided inside the support member 6.
For example, when the support member 6 is made of a metal material, the support member 6 has electromagnetic shielding properties and is disposed so as to cover a part of a drive circuit 821 and a wiring unit 9 described later. As a result, it is possible to prevent electromagnetic adverse effects between the drive circuit 821 and part of the wiring unit 9 and the outside. As a result, the exposure characteristics of the line head 13 can be improved.

Moreover, the support member 6 can be made to have excellent rigidity of the support member 6 with a relatively simple structure by configuring the support member 6 so as to have a substantially U-shaped cross section as described above. Further, by supporting the substrate 71 by the substrate mounting portion 61, the substrate 71 can be stably supported and stable exposure processing can be performed. In particular, since the substrate mounting portion 61 has a high flatness, the flatness of the substrate 71 can be maintained in a high state.
Moreover, the support member 6 can be obtained comparatively easily and inexpensively when the metal plate is bent.
Further, the support member 6 has a function (light-shielding property) for preventing light that has not entered the lens array 16 described later from each light emitting element 72 from leaking to the outside.

  In particular, the support member 6 is in close contact with the surface of the spacer 17 opposite to the substrate 71 side. Thereby, it is possible to prevent an air layer from being formed between the support member 6 and the surface of the spacer 17 opposite to the substrate 71 side. As a result, it is possible to prevent light incident on the spacer 17 from the light emitting element 72 from being reflected on the surface of the spacer 17 opposite to the substrate 71 side. Therefore, it is possible to prevent unnecessary light (ghost light) from being emitted from the lens array 16 and to realize high-precision exposure processing.

  Further, the support member 6 is in close contact with the side surface of the spacer 17. Thereby, it is possible to prevent an air layer from being formed between the support member 6 and the side surface of the spacer 17. As a result, the light incident on the spacer 17 from the light emitting element 72 can be prevented from being reflected by the side surface of the spacer 17. Therefore, it is possible to prevent unnecessary light (ghost light) from being emitted from the lens array 16 and to realize high-precision exposure processing.

Thus, in this embodiment, since there is almost no air layer between the support member 6 and the spacer 17, unnecessary light (ghost light) is more reliably prevented from being emitted from the lens array 16, and extremely A highly accurate exposure process can be realized.
The constituent material of the support member 6 is not particularly limited, and various metal materials (particularly soft magnetic materials) can be used, but iron, stainless steel, aluminum alloy, and the like are preferably used.
In this way, the support member 6 supports the light emitting substrate unit 7.

The light emitting substrate unit 7 includes an elongated substrate 71, a plurality of light emitting elements 72 arranged on one surface side of the substrate 71 along the longitudinal direction, and a sealing member 73 that covers the plurality of light emitting elements 72. And.
The board | substrate 71 is what supports each light emitting element 72 (board | substrate), and is comprised with the plate-shaped body from which an external shape makes long shape.

The substrate 71 is made of a glass material. That is, the substrate 71 is a glass substrate. A glass substrate has insulation and light transmittance. Therefore, when the substrate 71 is a glass substrate, an organic electroluminescence element can be formed as the light emitting element 72 on the substrate 71 relatively easily and inexpensively. Further, as described later, the light L from each light emitting element 72 having the bottom emission structure can be emitted through the substrate 71. Further, since the flatness of the glass substrate is relatively high, the use of the glass substrate as the substrate 71 reduces the variation in the distance between the light emitting element 72 and the lens array 16, and the lens array 16 is formed on the photosensitive drum 11. The light L can be imaged on the light receiving surface 111 with high accuracy.
In addition, by configuring the substrate 71 with a glass material, the heat generated by the light emission of each light emitting element 72 can be efficiently radiated to the support member 6 and the like via the substrate 71.

In such a substrate 71, a plurality of light emitting elements 72 and a sealing member 73 are bonded to one surface (the lower surface in FIG. 2).
The plurality of light emitting elements 72 are arranged on the 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 substrate 71.

Each light emitting element 72 is configured by an organic EL element (organic electroluminescence element).
More specifically, 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, as shown in FIG. These are provided on the substrate 71.
In this embodiment, the organic semiconductor layer 723 includes a plurality of layers that are 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 such a light emitting element 72, when a DC voltage is applied between the anode 722 and the cathode 724, the electrons transported through the electron transport layer 728 and the hole transport layer in the light emitting layer 727 are thereby generated. The holes transported through 726 recombine, and exciton (exciton) is generated by the energy released during the recombination. When the exciton returns to the ground state, the energy is converted to light L (fluorescence or phosphorescence). ). 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 such hole transport materials include arylcycloalkane compounds such as 1,1-bis (4-di-para-triaminophenyl) cyclohexane, 4,4 ′, 4 ″ -trimethyl. Arylamine compounds such as triphenylamine, phenylenediamine compounds such as N, N, N ′, N′-tetraphenyl-para-phenylenediamine, triazole compounds such as triazole, imidazoles such as imidazole Compounds, 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 Compounds, etc., one of these or It can be used in combination of more than seeds.

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-tris [{3- (4-t-butylphenyl) -6-trisfluoromethyl} quinoxalin-2-yl] benzene (TPQ2), phthalocyanine, copper phthalocyanine (CuPc), iron phthalocyanine Low molecular weight compounds such as metal or metal-free phthalocyanine compounds such as tris (8-hydroxyquinolinolate) aluminum (Alq ₃ ), factory (2-phenylpyridine) iridium (Ir (ppy) ₃ ) Polymers such as oxadiazole polymers, triazole polymers, carbazole polymers The light L which has the target luminescent color can be obtained combining these 1 type (s) or 2 or more types.

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. In other words, the arrangement density of the light emitting elements 72 in the longitudinal direction (main scanning direction) of the substrate 71 can be increased while suppressing the number of light emitting elements 72 in the width direction (sub scanning direction) of the substrate 71. 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, when the light emitting element 72 is formed, a part of a driving circuit for driving the light emitting element 72 is configured together with the light emitting element 72. A TFT, wiring, or the like can be formed on the 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.
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 substrate 71 together with each of the light emitting elements 72 has a recess 731, and the peripheral portion of the recess 731 is made of an adhesive or the like. 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 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.
A desiccant and / or an oxygen scavenger is preferably 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 (Cs ), Tantalum fluoride (TaF _5), niobium fluoride (NbF _5), calcium bromide (CaBr _2), cerium bromide (CeBr _3), bromide selenium (SEBR _4), vanadium bromide (VBr _2), magnesium bromide (MgBr _2), barium iodide (BaI _2), magnesium iodide (MgI _2), barium perchlorate _{(Ba (ClO 4) 2)} , magnesium perchlorate (Mg (ClO _{4) 2),} etc. Is mentioned.
Examples of the oxygen scavenger include activated carbon, silica gel, activated alumina, molecular sieve, magnesium oxide, iron oxide, and titanium oxide.

  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, a resin material such as acrylic resin or styrene resin. Etc. can be used, but a glass material is preferably used. By comprising both the sealing member 73 and the board | substrate 71 with glass material, malfunctions, such as a deformation | transformation by the linear expansion coefficient difference between these, damage, etc. can be prevented.

On the other hand, the lens array 16 is bonded to the other surface (the upper surface in FIG. 2) of the substrate 71 via the spacer 17.
The lens array 16 is provided on the light L emission side of the light emitting substrate unit 7. The lens array 16 is an imaging optical system that forms an image of light from the light emitting element 72 described above.
The lens array 16 shown in FIG. 2 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 substrate 71. Each rod lens 161 is made of, for example, a light-transmissive resin material and / or glass material.

  The spacer 17 is provided between the substrate 71 and the lens array 16, supports the lens array 16 with respect to the substrate 71, and defines an optical path length between the substrate 71 and the lens array 16. The spacer 17 has a plate shape and is made of, for example, a resin material and / or a glass material having optical transparency. By providing such a spacer 17, the distance between each light emitting element 72 and the lens array 16 can be adjusted according to the thickness of the spacer 17. As a result, highly accurate exposure processing can be realized with a relatively simple configuration.

  The spacer 17 is a light transmissive substrate, and the lens array 16 is bonded to and supported by the spacer 17. Thereby, the distance between each light emitting element 72 and the lens array 16 can be prescribed | regulated easily and correctly.

Further, since the spacer 17 has a plate shape, the distance between each light emitting element 72 and the lens array 16 and the distance between the substrate 71 and the support member 6 can be accurately and stably. Can be prescribed.
The spacer 17 is bonded to the substrate 71. As a result, the spacer 17 can be stably supported with respect to the substrate 71. As a result, the spacer 17 can more stably support the lens array 16 with respect to the substrate 71.

In particular, as shown in FIG. 2, the width W _S of the sub-scanning direction (first vertical or substantially vertical second direction in the direction) of the spacer 17, than the width W _B of the sub-scanning direction of the substrate 71 Is also big.
The end of the substrate 71 in the sub-scanning direction is configured not to protrude outward from the end of the spacer 17 in the sub-scanning direction.
Thereby, the edge part in the width direction of the board | substrate 71 is reinforced with the spacer 17, and the mechanical strength of the said edge part increases. Therefore, it is possible to prevent chipping or cracking of the end portion in the width direction of the substrate 71 when the line head 13 is assembled.

  The width of the spacer 17 in the main scanning direction (first direction) is larger than the width of the substrate 71 in the main scanning direction, and the end of the substrate 71 in the main scanning direction is the end of the spacer 17 in the main scanning direction. It is preferable that it is configured not to protrude outward. In other words, the spacer 17 is preferably configured to include the substrate 71 when viewed in plan. Thereby, it is also possible to prevent the end portion of the substrate 71 from cracking or chipping in the main scanning direction.

Further, as described above, the surface of the spacer 17 opposite to the substrate 71 is in close contact with the support member 6 having a light shielding property. The side surface of the spacer 17 </ b> A is also in close contact with the support member 6. Therefore, in the present embodiment, since no air layer exists between the support member 6 and the spacer 17, unnecessary light (ghost light) due to reflection on the side surface or the upper surface of the spacer 17 is emitted from the lens array 16. Can be reliably prevented, and an extremely accurate exposure process can be realized.
A control circuit 822, which will be described later, is electrically connected to the light emitting substrate unit 7 described above via a wiring unit 9.

Here, the control system of the line head 13 will be described with reference to FIGS.
As shown in FIG. 4, 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 the present 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 of the constant current driving circuits 83 as described above, when the selection transistor 833 is turned on, a constant current corresponding 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. . Further, 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 such a 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 drive 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. 5 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 constant current drive circuits 83 and the selection switches 84 are circuit units provided on the substrate 71 described above. The driver IC 85 is a semiconductor element provided on the wiring unit 9 described later.

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.
Such a 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. 4, the interface circuit 86 is composed of 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 optimum, 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 transmitter 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 part of the image forming apparatus 1.
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 wiring unit 9 is provided so as to be drawn out from the lower surface (one surface) of the substrate 71 in the sub-scanning direction.
The wiring unit 9 includes wiring for electrically connecting the above-described circuit portion on the light emitting substrate unit 7 and a circuit portion outside the light emitting substrate unit 7 (hereinafter also referred to as “external circuit”) (wiring). Part).
In the present embodiment, the wiring unit 9 is composed of a plurality of flexible printed circuit boards (FPCs). Thereby, the freedom degree of installation of the external circuit with respect to the board | substrate 71 can be raised. The wiring unit 9 may be composed of a single flexible printed circuit board (FPC).

As shown in FIG. 2, the wiring unit 9 (flexible printed circuit board) is fixed to one end of the substrate 71 in the width direction. 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).
One end of the wiring of the wiring unit 9 is connected to the wiring on the substrate 71 using an anisotropic conductive adhesive (ACF) or the like.

Here, one end of the wiring of the wiring unit 9 is connected to the end of the lower surface of the substrate 71 in the sub-scanning direction. As described above, since the end portion of the substrate 71 in the sub-scanning direction is reinforced by the spacer 17, even when an external force is applied to the wiring unit 9 when the line head 13 is assembled, the sub-scanning of the substrate 71 is performed. It is possible to prevent cracking or chipping at the end in the direction.
In the present embodiment, one end portion (left end portion in FIG. 2) of the spacer 17 in the sub-scanning direction protrudes outward from the end of the substrate 71. This prevents external force from being applied to the wiring unit 9 during assembly of the line head 13 or the like (prevents contact with other objects) and prevents the wiring unit 9 from being peeled from the substrate 71. .

According to the line head 13 as described above, the width W _S of the sub-scanning direction of the spacer 17 is larger than the width W _B of the sub-scanning direction of the substrate 71, the spacer is an end in the sub-scanning direction of the substrate 71 Since the end portion in the width direction of the substrate 71 is reinforced by the spacer 17, the mechanical strength of the end portion increases. Therefore, it is possible to prevent chipping or cracking of the end portion in the width direction of the substrate 71 when the line head 13 is assembled.

In particular, one end portion of the spacer 17 in the sub-scanning direction (the end portion on the connection side between the substrate 71 and the wiring unit 9) protrudes outward from the end of the substrate 71. This prevents external force from being applied to the wiring unit 9 during assembly of the line head 13 or the like (prevents contact with other objects) and prevents the wiring unit 9 from being peeled from the substrate 71. .
Further, since the substrate 71 and the spacer 17 are accommodated in the support member 6, it is possible to prevent light that has not entered the lens array 16 from the light emitting element 72 from leaking to the outside.
In this way, the line head 13 is excellent in assemblability and can realize highly accurate exposure processing. Further, the image forming apparatus 1 provided with such a line head 13 is inexpensive and can obtain a high-quality image.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
FIG. 6 is a cross-sectional view of a line head according to the second embodiment of the present invention.
Hereinafter, the line head according to the second embodiment will be described focusing on the differences from the first embodiment described above, and description of similar matters will be omitted.
The line head 13A of the present embodiment is the same as the line head 13 of the first embodiment described above except that the configuration of the spacer and the support member is different.

In the line head 13A of the present embodiment, as shown in FIG. 6, a spacer 17A interposed between the substrate 71 and the lens array 16 and a support member 6A provided so as to cover the upper surface side of the spacer 17A are provided. Have.
In the present embodiment, the width W _S of the sub-scanning direction of the spacer 17A is substantially equal to the width W _B of the sub-scanning direction of the substrate 71, and the sub-scanning direction of the end spacer 17A in the sub scanning direction of the substrate 71 It is comprised so that it may not protrude outside from the edge in.
Thereby, the edge part in the width direction of the board | substrate 71 is reinforced with the spacer 17A, and the mechanical strength of the said edge part increases. Therefore, it is possible to prevent the end portion from being chipped or cracked in the width direction of the substrate 71 when the line head 13A is assembled.

Further, the support member 6A is provided with a stepped portion 63 so as to widen the width of the internal space in the sub-scanning direction.
By providing such a stepped portion 63, contact between the bent portion near the substrate 71 of the wiring unit 9 and the support member 6A can be prevented during assembly. As a result, it is possible to prevent the wiring unit 9 from being peeled from the substrate 71.

The line head and the image forming apparatus of the present invention have been described above with respect to the illustrated embodiment. However, the present invention is not limited to this, and each part constituting the line head and the image forming apparatus has the same function. It can be replaced with any configuration that can be exhibited. Moreover, arbitrary components may be added.
The lens array is not limited to a plurality of lenses arranged in a matrix of 2 rows and n columns, and may be arranged in a matrix of 3 rows and n columns, 4 rows and n columns, for example.

Also, a microlens array in which a large number of microlenses are arranged can be used as the lens array.
In the above-described embodiment, for convenience of explanation, the light emitting elements are arranged in 1 row and n columns. However, the present invention is not limited to this, and the light emitting elements are 2 rows n columns, 3 rows n columns, and the like. May be arranged in a matrix.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 6, 6A ... Support member 61 ... Board | substrate mounting part 611 ... Opening part 62 ... Leg part 63 ... Step part 7 ... Light emitting board unit 71 ... Substrate 72 ... Light emitting element 73 ... Sealing member 722 ... Anode 723 ... Organic semiconductor layer 724 ... Cathode 726 ... Hole transport layer 727 ... Light emitting layer 728 ... Electron transport layer 8 ... Circuit board unit 81 ... Second substrate 82 ... Circuit portion 821, 821A ... Drive circuit 822 ... Control circuit 83 ... Constant current Drive circuit 831 ... Constant current transistor 832 ... Voltage holding capacitor 833 ... Selection transistor 84, 84A ... Selection switch 85, 85A ... Driver IC 851 ... Shift register 852 ... Latch circuit 853 ... DAC 86 ... Interface circuit 87 ... Data control circuit 88 ... Correction value memory 9... Wiring units 91 and 92 Folding portion 10 ... Image forming unit 10C, 10K, 10M, 10Y ... Image forming station 11 ... Photosensitive drum (latent image carrier) 111 ... Light receiving surface 12 ... Charging unit 13, 13A ... Line head (exposure unit) 14 ... Developing device DESCRIPTION OF SYMBOLS 15 ... Cleaning unit 151 ... Cleaning blade 16 ... Lens array 161 ... Rod lens 17, 17A ... Spacer 181 ... Head control part 182 ... Transmission circuit 20 ... Transfer unit 21 ... Intermediate transfer belt 22 ... Primary transfer roller 23 ... Drive roller 24 ... Follower roller 25 ... secondary transfer roller 26 ... cleaning unit 261 ... cleaning blade 30 ... fixing unit 301 ... fixing roller 302 ... pressure roller 40 ... conveying mechanism 41 ... registration roller pair 42, 43, 44 ... conveying Over roller pair 50 ... sheet feeding unit 51 ... sheet cassette 52 ... pick-up roller 18 ... printer controller 731 ... recess P ... recording medium L ... Light

Claims (5)

A substrate having optical transparency;
A light emitting device disposed in a first direction on one side of the substrate;
A spacer bonded to the other surface opposite to the one surface of the substrate and having light transmittance;
An imaging optical system that is bonded to a surface of the spacer facing the substrate-side surface and forms an image of light from the light-emitting element;
The spacer is provided so as to cover a surface facing the surface on the substrate side, and includes a light-shielding support member that includes the opening through which the imaging optical system is inserted and supports the substrate.
A width of the spacer in a second direction perpendicular to the first direction is equal to or greater than a width of the substrate in the second direction;
The line head is configured such that one end of the substrate in the second direction does not protrude outward from the one end of the spacer in the second direction.   The line head according to claim 1, further comprising a wiring portion provided so as to be drawn out from the one surface of the substrate in the second direction.   The line head according to claim 1, wherein the cover member is in close contact with a surface of the spacer opposite to the surface on the substrate side.   4. The line head according to claim 1, wherein the cover member is in close contact with a side surface that is perpendicular or substantially perpendicular to the one surface of the spacer. 5. A latent image carrier on which a latent image is formed;
A line head for exposing the latent image carrier,
The line head is
A substrate having optical transparency;
A light emitting device disposed in a first direction on one side of the substrate;
A spacer bonded to the other surface opposite to the one surface of the substrate and having light transmittance;
An imaging optical system that is bonded to a surface of the spacer facing the substrate-side surface and forms an image of light from the light-emitting element;
The spacer is provided so as to cover a surface facing the surface on the substrate side, and includes a light-shielding support member that includes the opening through which the imaging optical system is inserted and supports the substrate.
A width of the spacer in a second direction perpendicular to the first direction is equal to or greater than a width of the substrate in the second direction;
An image forming apparatus, wherein one end of the substrate in the second direction does not protrude outward from the one end of the spacer in the second direction.

Images