JP2010058349A - Line head and image forming apparatus - Google Patents

Abstract

The present invention provides a line head capable of realizing high-precision exposure processing while making the image forming apparatus small and inexpensive while having a narrow width, and is small and inexpensive capable of obtaining a high-quality image. An image forming apparatus is provided.
A line head 13 includes a support member 6, a first substrate 71 which is a long glass substrate supported by the support member 6, and a first substrate 71 along a longitudinal direction thereof. A light-emitting substrate unit 7 including a plurality of light-emitting elements 72 arranged, the support member 6 is formed by bending a metal plate, and the support member 6 has a long plate shape. The board mounting portion 61 is formed, and a pair of legs 62 extending from both ends in the width direction of the substrate mounting portion 61 to one surface side of the substrate mounting portion 61. The first substrate 71 is a substrate mounting portion. Each light emitting element 72 mounted on the part 61 is an organic electroluminescence element.
[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 is known (see, for example, Patent Document 1).

For example, in the line head according to Patent Document 1, a plurality of light emitting diode elements are linearly arranged on a base plate bonded and fixed to a resin housing. A lens array is disposed on the light emission side of the light emitting diode element. In such a line head, the light from the light emitting diode element is imaged on the outer surface of the photoreceptor through the lens array, and exposure processing is performed.
In the line head according to Patent Document 1, since the base plate is made of glass epoxy or the like, the flatness of the plate surface of the base plate is low. Further, since the housing that supports the base plate is made of resin, the rigidity of the base plate is low. In this respect, the flatness of the base plate is also lowered. As a result, a variation in the distance between the light emitting diode element and the lens array occurs, and light cannot be imaged with high accuracy on the outer surface of the photoreceptor via the lens array. Further, since the light emitting diode element is used, an IC or the like for driving the light emitting diode element must be mounted on the base plate, so that the width of the base plate is wide, and as a result, the width of the entire line head is wide. turn into. This is a major obstacle to downsizing the image forming apparatus.

JP-A-6-320789

  An object of the present invention is to provide a line head capable of realizing high-precision exposure processing while making the image forming apparatus small and inexpensive with a narrow width, and to obtain a high-quality image. An object is to provide a small and inexpensive image forming apparatus.

Such an object is achieved by the present invention described below.
A line head of the present invention includes a light emitting substrate unit comprising a glass substrate and a light emitting element that is an organic electroluminescence element disposed in a first direction of the glass substrate;
A support member that is formed by bending a metal plate and includes a bent portion, a substrate mounting portion that supports the light emitting substrate unit, and a leg portion;
It is characterized by having.

In the line head according to the aspect of the invention, it is preferable that the light emitting element is a bottom emission type organic electroluminescence element.
In the line head according to the aspect of the invention, the light-emitting element unit includes a sealing member bonded to the glass substrate so as to cover the light-emitting element, and the sealing member includes glass as a main material, and the glass The substrate is preferably joined to the support member via the sealing member.

The line head of the present invention preferably has a lens array provided on the light emission side of the light emitting substrate unit, and the lens array is preferably bonded via a spacer.
In the line head of the present invention, a circuit board unit including a circuit board, and an interface circuit provided on the circuit board, to which a signal for driving the light emitting element is input,
A wiring unit comprising wiring for electrically connecting the light emitting board unit and the circuit board unit;
It is preferable to have.

In the line head according to the aspect of the invention, it is preferable that the circuit board is a printed board.
In the line head according to the aspect of the invention, it is preferable that the wiring unit is a flexible printed board.
The image forming apparatus of the present invention is formed by bending a metal plate and a light emitting substrate unit including a glass substrate and a light emitting element that is an organic electroluminescence element arranged in a first direction of the glass substrate. A line head having a bent portion, a substrate mounting portion for supporting the light emitting substrate unit, and a support member including legs.
A latent image carrier on which a latent image is formed by the line head;
It is characterized by having.

  According to the line head of the present invention having the above-described configuration, since the flatness of the plate surface of the glass substrate is relatively high, variations in the installation position of the light emitting element in the optical axis direction can be reduced. In particular, since the support member has a configuration in which a metal plate is bent to have a substrate mounting portion and a pair of leg portions, the rigidity (particularly bending stiffness) of the support member can be increased, and the support member supports it. The flatness of the glass substrate to be maintained can be maintained in a high state. As a result, highly accurate exposure processing can be realized.

Moreover, since the glass substrate is arrange | positioned on the outer side of a supporting member, the width | variety of a glass substrate can be narrowed. As a result, it is possible to reduce the width of the line head and thereby reduce the size of the image forming apparatus.
Further, according to the image forming apparatus of the present invention, the diameter of the photoreceptor can be reduced by mounting the narrow line head as described above, and as a result, a high-quality image can be obtained. , Small and inexpensive.

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. FIG. 4 is a cross-sectional view showing a schematic configuration of the light emitting element provided in the line head shown in FIG. 2, and FIG. 4 shows the relationship between the first substrate, the second substrate, and the wiring unit provided in the line head shown in FIG. FIG. 5 is a diagram for explaining the configuration of the control system of the line head shown in FIG. 2, FIG. 6 is a diagram for explaining a modification of the control system shown in FIG. 5, FIG. 7 and FIG. These are the figures for demonstrating the modification of the relationship of the circuit of a control system shown in FIG. 5, a 1st board | substrate, a 2nd board | substrate, and a wiring unit, respectively. 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 has a photosensitive drum (photosensitive member) 11 that carries an electrostatic latent image, and a charging unit 12 and a line head (exposure) are provided around (outer peripheral side). A unit) 13, a developing device 14, and a cleaning unit 15. 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, and transfers a single color toner image on the photosensitive drum 11 to the intermediate transfer belt 21 (primary transfer). It is like that. 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. In addition, a heater 303 that heats 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 to face the outer peripheral surface (that is, 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, a light emitting substrate unit 7, a circuit board unit 8, a wiring unit 9, a lens array 16, a spacer 17, a light shielding member 19, And a heat dissipating member 60.

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 of the first substrate 71 of the light emitting substrate unit 7 is referred to as “main scanning direction”, and the width 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.
The support member 6 is formed by bending a metal plate, and includes a substrate mounting portion 61 and a pair of leg portions 62. The support member 6 has a substantially U-shaped cross section. Yes. Further, the support member 6 has a bent portion 64 formed between the substrate mounting portion 61 and each leg portion 62.

The substrate mounting portion 61 is provided along the plate surface of the first substrate 71 in a cross section shown in FIG. 2 (a cross section perpendicular to the longitudinal direction of the first substrate 71 described later).
The substrate mounting portion 61 has a long plate shape, and a first substrate 71 of the light emitting substrate unit 7 described later is mounted on one surface side (the upper side in FIG. 2). As a result, the substrate mounting portion 61 supports the first substrate 71.

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 side opposite to the first substrate 71. 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 side portions in the longitudinal direction). Thereby, the light emitting substrate unit 7 is provided outside the support member 6.
Such a support member 6 can be made to have excellent rigidity of the support member 6 with a relatively simple configuration by configuring the support member 6 to have a substantially U-shaped cross section as described above. . Further, by supporting the first substrate 71 by the substrate mounting portion 61, the first substrate 71 can be stably supported and a stable exposure process can be performed. The support member 6 may also support (fix) a second substrate 81 described later.

Since such a support member 6 is formed by bending a metal plate, it can be obtained relatively easily and inexpensively.
Further, since the first substrate 71 is installed outside the support member 6, the assembly is easier than installing the first substrate 71 inside the support member 6. As a result, the line head 13 can be made inexpensive.

In addition, since the first substrate 71 is installed outside the support member 6, the width of the support member 6 can be made smaller than the width of the first substrate 71. Therefore, the line head 13 can be narrowed.
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.

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. And a sealing member (cover member) 73 for covering.
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 made of a glass material. That is, the first substrate 71 is a glass substrate. 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, as will be described later, the light L from each light emitting element 72 having the bottom emission structure can be emitted through the first substrate 71. Further, since the flatness of the glass substrate is relatively high, by using the glass substrate for the first substrate 71, variation in the distance between the light emitting element 72 and the lens array 16 is reduced, and the lens array 16 is exposed to light. The light L can be imaged with high accuracy on the light receiving surface 111 of the body 11.

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 support member 6 and the like via the first substrate 71.
In such a first 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 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.

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 first substrate 71.

Further, in the present embodiment, the organic semiconductor layer 723 is a laminate composed of a plurality of layers laminated in this order from the anode 722 side, the hole transport layer 726, the light emitting layer 727, and the electron transport layer 728. Yes.
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 the exciton (exciton) is generated by the energy released during the recombination. When the exciton returns to the ground state, the energy (fluorescence or phosphorescence) is light. Released as L. 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 generally used in an electrophotographic process are 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 materials.
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.

  Moreover, when each light emitting element 72 is comprised with the organic EL element, suppressing the number of the light emitting elements 72 in the width direction of the 1st board | substrate 71, the light emitting element 72 in the longitudinal direction of the 1st board | substrate 71 is used. The arrangement density 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.

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.
Further, the sealing member 73 provided on the one surface side of the first substrate 71 together with the plurality of light emitting elements 72 as described above has a recess 731 formed as shown in FIG. The part is bonded to the first substrate 71 by an adhesive or the like. 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.
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.
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 supporting member 6 can be simply and stably joined via the governor 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, 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.

On the other hand, the lens array 16 is bonded to the other surface (the upper surface in FIG. 3) of the first 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. 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 substrate 71. Each rod lens 161 is made of, for example, a resin material and / or a glass material.

  The spacer 17 defines the distance between each light emitting element 72 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. 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.

  In particular, the spacer 17 is a light transmissive substrate, and the lens array 16 is bonded to and supported by the spacer 171. Thereby, the distance between each light emitting element 72 and the lens array 16 can be prescribed | regulated easily and correctly. Further, since it is not necessary to support the lens array 16 with the light shielding member 19, for example, the thickness of the light shielding member 19 can be reduced, and as a result, the width of the line head 13 can be reduced.

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 first substrate 71 and the support member 6 can be set with high accuracy. It can be defined stably.
A light shielding member 19 is bonded and supported on the upper surface of the spacer 17. The light shielding member 19 has a function of preventing light that has not entered the lens array 16 described later from each light emitting element 72 from leaking to the outside.

  Such a light shielding member 19 is formed so as to cover the formation region of the plurality of light emitting elements 72. The light shielding member 19 has an opening 191 that penetrates in the optical axis direction of each light emitting element 72, and the lens array 16 is provided so as to penetrate the inside and outside of the light shielding member 19 through the opening 191. .

The constituent material of the light shielding member 19 is not particularly limited as long as it has a light shielding property, and a resin material, a metal material, or the like can be used.
The light shielding member 19 can be formed using injection molding, press molding, or the like.
As described above, the circuit board unit 8 is connected to the light emitting board unit 7 via the wiring unit 9.

The circuit board unit 8 includes a second board 81 and a circuit unit 82 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 to be perpendicular to the plate surface of the first substrate 71 described above.

  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, the second substrate 81 installed in this way has the width of the line head 13. Can be installed so as not to affect. Accordingly, the above-described drive circuit for driving each light emitting element 72 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.

In the present embodiment, the second substrate 81 is installed outside the support member 6 and in the vicinity of the leg portion 62 on the connection portion side between the first substrate 71 and the wiring unit 9.
As a constituent material of the second substrate 81, the same constituent material as that of the first substrate 71 described above can be used, but a mixed material of a glass material and a resin 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.

The wiring unit 9 is connected to one surface (surface on the side of the nearby leg portion 62) of the second substrate 81, and the other surface (surface opposite to the leg portion 62 in the vicinity) is connected to the other surface. A circuit unit 82 is provided.
As shown in FIG. 5, 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.
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 selection transistor 832, and a low voltage transistor 833.

  In each of the constant current driving circuits 83 as described above, when the selection transistor 832 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 832) 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.
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 this embodiment, as shown in FIG. 5, 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 interface circuit 86 and the printer controller 18 are electrically connected via an FFC (flexible flat cable) 183.

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 main body controller 18 also has a function of controlling each unit of the image forming apparatus 1.

As shown in FIG. 4, the circuit unit 82 includes an interface circuit 86 (control circuit 822) provided on the second substrate 81, a driver IC 85 provided on the wiring unit 9, and a constant current drive circuit 83. Is provided on the first substrate 71.
Note that the driver IC 85 may be provided on the first substrate 71 as shown in FIG. Further, as shown in FIG. 8, a drive circuit 821 </ b> A in which a circuit 85 </ b> A having the same function as the driver IC 85 is formed together with the constant current drive circuit 83 may be formed on the first substrate 71.

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 via the wiring of the wiring unit 9.
The wiring unit 9 includes wiring for electrically connecting the light emitting board unit 7 and the circuit board unit 8 described above.

  In the present embodiment, the wiring unit 9 is composed of a plurality of flexible printed circuit boards (FPCs). 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 wiring unit 9 may be composed of a single flexible printed circuit board (FPC).

  As shown in FIGS. 2 and 4, the wiring unit 9 (flexible printed circuit board) is fixed to one end in the width direction of each 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. 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 this embodiment, as shown in FIG. 5, when the light emitting board unit 7, the circuit board unit 8, and the wiring unit 9 are developed on a plane, the wiring unit 9 (flexible printed circuit board) The substrate 71 and the second substrate 81 are bonded to the same surface. Thereby, when connecting the wiring unit 9 to the 1st board | substrate 71 and the 2nd board | substrate 81, the process becomes simple, As a result, the line head 13 can be made cheaper.

One end of the wiring of the wiring unit 9 is connected to the wiring on the first substrate 71 using an anisotropic conductive adhesive (ACF) or the like. The other end of the wiring of the wiring unit 9 may be connected to the wiring on the second substrate 81 using an anisotropic conductive adhesive (ACF) or the like, or connected using a connector. May be.
In the present embodiment, the driver IC 85 is provided on the wiring unit 9 as described above. A heat radiating member 60 is provided in contact with the driver IC 85.

The heat radiating member 60 has a function of radiating heat from the driver IC 85.
The constituent material of the heat radiating member 60 is not particularly limited as long as the driver IC 85 can radiate heat, but copper, aluminum, an alloy thereof, or the like is preferably used.
In the present embodiment, the heat radiating member 60 has a plate shape and is disposed along one leg portion 62 of the support member 6. Moreover, the heat radiating member 60 is supported by the support member 6 via a member (not shown). Needless to say, the shape of the heat dissipation member 60 is not limited to that described above. Further, the heat dissipation member 60 may be configured by a part of the support member 6 or a part of the light shielding member 19.

According to the line head 13 as described above, since the flatness of the plate surface of the glass substrate is relatively high, by using the glass substrate for the first substrate 71, the optical substrate of the plurality of light emitting elements 72 can be used in the optical axis direction. The variation in the installation position of can be reduced. In particular, since the support member 6 is configured to bend the metal plate and have the substrate mounting portion 61 and the pair of leg portions 62, the support member 6 can have high rigidity (particularly bending rigidity). The flatness of the first substrate 71 supported by the support member 6 can be maintained in a high state. As a result, highly accurate exposure processing can be realized.
In addition, since the first substrate 71 is disposed outside the support member 6, the width of the first substrate 71 can be reduced. As a result, the width of the line head 13 can be reduced, and consequently the image forming apparatus 1 can be reduced in size.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
FIG. 9 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 this embodiment is the same as the line head 13 of the first embodiment described above except that the configuration of the support member and the circuit board unit and the installation positions of the circuit board unit and the wiring unit are different.
In the line head 13A of this embodiment, as shown in FIG. 9, the first substrate 71 of the light emitting substrate unit 7 is supported by the support member 6A, and the circuit board unit 8A is supported on the light emitting substrate unit 7 via the wiring unit 9. It is connected.

The support member 6 </ b> A has a substrate mounting portion 61 and a pair of leg portions 62, as in the first embodiment described above, and an opening 63 near the boundary between the substrate mounting portion 61 and one leg portion 62. Is formed.
The wiring unit 9 is inserted through the opening 63, and the circuit board unit 8A is disposed inside the support member 6A. Thereby, the width of the line head 13B becomes smaller. Further, by disposing the circuit board unit 8A inside the support member 6A, it is possible to prevent an adverse electromagnetic effect between the circuit board unit 8A and the outside.

  The circuit board unit 8 </ b> A is electrically connected to the wiring unit 9 via a connector 89 provided on the second board 81. The connector 89 is electrically connected to the circuit unit 85 described above. Providing such a connector 89 facilitates assembly of the line head 13.

In the present embodiment, one leg portion 62 of the support member 6A is in contact with the driver IC 85, and a part of the support member 6A also serves as a heat dissipation member.
According to the line head 13A as described above, in addition to the same effects as those of the line head 13 according to the first embodiment described above, it is possible to further reduce the size and cost.

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.

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 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 for demonstrating the relationship between the 1st board | substrate with which the line head shown in FIG. 2 was equipped, the 2nd board | substrate, and the wiring unit. It is a block diagram 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. FIG. 6 is a diagram for explaining a modification of the relationship among the control system circuit, the first substrate, the second substrate, and the wiring unit shown in FIG. 5. FIG. 6 is a diagram for explaining a modification of the relationship among the control system circuit, the first substrate, the second substrate, and the wiring unit shown in FIG. 5. It is a cross section of the line head concerning 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 6, 6A ... Support member 61 ... Board | substrate mounting part 62 ... Leg part 63 ... Opening part 64 ... Bending part 7 ... Light emission board | substrate unit 71 ... 1st board | 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 10 ... Image forming unit 10C, 10K, 10M, 10Y ... Image forming station 11 ... Photosensitive drum (photoconductor) 111 Light receiving surface 12 ... Charging unit 13, 13A, 13B ... Line head (exposure unit) 14 ... Developing device 15 ... Cleaning unit 151 ... Cleaning blade 16 ... Lens array 161 ... Rod lens 17 ... Spacer 20 ... Transfer unit 21 ... Intermediate transfer belt 22 ... Primary transfer roller 23 ... Drive roller 2 4 ... driven roller 25 ... secondary transfer roller 26 ... cleaning unit 261 ... cleaning blade 30 ... fixing unit 301 ... fixing roller 302 ... pressure roller 40 ... transport mechanism 41 ... registration roller pair 42, 43, 44 ... transport roller pair 50 ... Paper feeding unit 51 ... Paper feeding cassette 52 ... Pickup roller 8, 8A ... Circuit board unit 81 ... Second board 85, 85A ... Driver IC 821A ... Drive circuit 822 ... Control circuit 83 ... Constant current drive circuit 831 ... Constant current Transistor 832 ... Selection transistor 833 ... Low voltage transistor 84, 84A ... Selection switch 87 ... Data control circuit 88 ... Correction value memory 89 ... Connector 18 ... Printer controller 181 ... Head controller 182 ... Transmission circuit 183 ... FFC (flexible) 9 ... Wiring unit 19 ... Shading member 191 ... Opening 731 ... Recess 851 ... Shift register 852 ... Latch circuit 853 ... DAC P ... Recording medium Q ... Spot (latent image) L ... Light

Claims (8)

A light-emitting substrate unit comprising a glass substrate and a light-emitting element that is an organic electroluminescence element disposed in a first direction of the glass substrate;
A support member that is formed by bending a metal plate and includes a bent portion, a substrate mounting portion that supports the light emitting substrate unit, and a leg portion;
A line head characterized by comprising:   The line head according to claim 1, wherein the light emitting element is a bottom emission type organic electroluminescence element.   The light-emitting element unit has a sealing member bonded to the glass substrate so as to cover the light-emitting element, and the sealing member is composed mainly of glass, and the glass substrate is formed of the sealing member. The line head according to claim 2, wherein the line head is joined to the support member via a wire.   The line head according to claim 2, further comprising a lens array provided on a light emission side of the light emitting substrate unit, the lens array being bonded via a spacer. A circuit board unit provided with a circuit board, and an interface circuit provided on the circuit board, to which a signal for driving the light emitting element is input;
A wiring unit comprising wiring for electrically connecting the light emitting board unit and the circuit board unit;
The line head according to claim 1, comprising:   The line head according to claim 5, wherein the circuit board is a printed board.   The line head according to claim 5, wherein the wiring unit is a flexible printed circuit board. A light-emitting substrate unit comprising a glass substrate and a light-emitting element that is an organic electroluminescence element disposed in a first direction of the glass substrate; a bent portion formed by bending a metal plate; and the light-emitting substrate unit A line head having a substrate mounting portion that supports the support member, and a support member that includes a leg portion,
A latent image carrier on which a latent image is formed by the line head;
An image forming apparatus comprising:

Images