JP2008238632A - Electrooptical device, image forming apparatus, and method for manufacturing electrooptical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate variation in brightness of a light emitting element and variation in density of an image caused by the variation in brightness in an electrooptical device equipped with an electrooptical panel having electrooptical elements arranged therein, for example, light emitting elements such as EL elements or light bulb elements, and an image forming apparatus using the electrooptical device. <P>SOLUTION: This electrooptical device comprises the electrooptical panel 2 having the plurality of electrooptical elements 21 each emitting light, a focusing lens array 4 having refraction index distribution type lenses 41 capable of imaging an upright image with respect to an image on the electrooptical panel 2 by transmitting the light emitted from the electrooptical panel 2, and a light transmissive member 3 which is interposed between the electrooptical panel 2 and the focusing lens array 4 and is adapted to guide the light emitted from the electrooptical panel 2 to the focusing lens array 4. The transmission factors of the light transmissive member 3 in the optical axis direction of the lenses 41 are differed from each other in the arrangement direction of the lenses 41. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an electro-optical device including an electro-optical panel in which electro-optical elements such as light-emitting elements such as EL elements or light valve elements are arranged, an image forming apparatus using the same, and a method for manufacturing the electro-optical device. .

Conventionally, in order to form an electrostatic latent image on an image carrier such as a photosensitive drum in an electrophotographic image forming apparatus, a plurality of light emitting elements such as electroluminescent elements (hereinafter referred to as EL elements), for example, A technique using a light emitting panel such as a light emitting element array (EL element array) arranged in a line has been developed. In such a technique, a converging lens array is generally disposed between a light emitting panel and an image carrier. In such an arrangement,
In order to reduce the loss of light emitted from the light-emitting panel, it has been proposed to dispose a light transmission member between the light-emitting panel and the converging lens array as described in Patent Document 1 below.

FIG. 9 is a perspective view schematically showing a part of a conventional image forming apparatus, and FIG. 10 is a side view thereof. In the image forming apparatus 1 of this example, a converging lens array 4 is disposed between a light emitting panel 2 such as an EL element array and an image carrier 10 such as a photosensitive drum, and the light emitting panel 2 and the converging lens array 4.
The light transmission member 3 is disposed between the two. As the convergent lens array 4, for example, there is an SLA (selfoc lens array) available from Nippon Sheet Glass Co., Ltd. (Selfoc and SELFOC are registered trademarks of Nippon Sheet Glass Co., Ltd.).

FIG. 11 is a perspective view showing a schematic configuration of the convergent lens array 4. The convergent lens array 4 has a plurality of gradient index lenses 41 arranged in a zigzag pattern in one direction (X direction in the figure). As the gradient index lens 41, for example, a graded index optical fiber configured such that the refractive index at the central axis is low and the refractive index increases as the distance from the central axis increases is used. In this configuration, the incident light is transmitted and an erect image corresponding to the image formed on the panel 2 is formed on the image carrier 10. The images obtained by the plurality of gradient index lenses 41 constitute one continuous image on the image carrier 10.

However, light emitting elements such as EL elements constituting the light emitting panel 2 have variations in brightness (brightness and power) as shown in FIG. 12, for example. In the figure, A1 represents the brightness of light emitted from the light emitting element, and A1 ′ represents the brightness on the imaging surface of the image carrier or the like. The above variations are caused by manufacturing variations of light emitting elements. If an electrostatic latent image is formed in a state where the brightness of such light emitting elements varies, a difference in density, density unevenness, etc. appear in the finally developed image, and a beautiful image cannot be obtained. Therefore, in order to eliminate the brightness variation of the light emitting element as described above, a function for correcting the above variation on a drive circuit such as a driver IC (for example, adjustment of current / voltage, light emission time, etc.) Etc.) are proposed.

JP 2006-218848 A JP 2006-289721 A

However, providing the above-described function on the drive circuit not only disadvantageously increases the size of the drive circuit and reduces the size of the light-emitting panel, but also has a disadvantage of increasing costs. In addition, to correct variations in brightness of light-emitting elements, it is necessary to repeatedly measure the brightness of the light-emitting elements and adjust the current, voltage, or light emission time. There is a problem that the manufacturing cost increases.

The present invention has been proposed in view of the above-described problems, and an electro-optical device that can easily eliminate problems such as variations in brightness of light-emitting elements and unevenness in image density due to the variations, and use thereof. It is an object of the present invention to provide an image forming apparatus and a method for manufacturing an electro-optical device.

In order to achieve the above object, an electro-optical device, a manufacturing method thereof, and a manufacturing method of an electro-optical device according to the present invention are configured as follows. In other words, the electro-optical device according to the present invention includes a plurality of electro-optical elements whose light emission characteristics or light transmission characteristics are changed by given electric energy, and which emits light from each of the plurality of electro-optical elements. An optical panel and a plurality of gradient index lenses that transmit light emitted from the electro-optical panel and can form an erect image with respect to the image on the electro-optical panel are arranged in a direction perpendicular to the optical axis direction of the lens. A converging lens array in which images obtained by the plurality of lenses constitute one continuous image, and light emitted from the electro-optical panel interposed between the electro-optical panel and the converging lens array And a light transmissive member for guiding the light to the converging lens array, and the light transmittance of the light transmissive member is made different in the arrangement direction of the lenses.

As described above, by making the light transmittance of the light transmitting member different in the lens arrangement direction, it is possible to easily eliminate problems such as unevenness in image density due to variations in brightness of a plurality of electro-optical elements. It becomes possible to do.

For example, the light transmissive member may have a structure in which one or more layers are laminated in the optical axis direction of the lens, and the light transmittance of the light transmissive member of at least one layer may be different in the arrangement direction of the lenses. Good. In this way, it is possible to eliminate defects such as unevenness of image density due to variations in brightness of the plurality of electro-optical elements, etc., only by changing the light transmittance of at least one light transmitting member constituting the light transmitting member. It can be easily solved.

Specifically, for example, the light transmittance of the light transmitting member is set to the brightness of light emitted from the plurality of electro-optical elements, or the light emitted from the plurality of electro-optical elements and transmitted through the converging lens array. The brightness may be varied according to the brightness of the light source, and more preferably, the brightness may be varied substantially in inverse proportion to the brightness. As a result, the brightness of the light emitted from the plurality of electro-optical elements or the brightness of the light emitted from the plurality of electro-optical elements through the converging lens array becomes brighter. The light transmittance is set to be low, and conversely, the light transmittance of the light transmissive member is set to be high as the above-described brightness decreases. Accordingly, it is possible to make the brightness and light transmittance uniform when the light transmitting member is interposed between the plurality of electro-optical elements and the converging lens array in the lens arrangement direction.

The image forming apparatus according to the present invention also includes an image carrier, a charger that charges the image carrier, and light that travels from the electro-optical panel and passes through the converging lens array. The electro-optical device that forms a latent image by irradiating the surface, a developing unit that forms a visible image on the image carrier by attaching toner to the latent image, and the developer from the image carrier. And a transfer device for transferring an image to another object. As described above, the image forming apparatus according to the present invention performs latent image formation using the electro-optical device configured as described above, thereby enabling formation of a latent image without variation and unevenness, and high-quality image formation. It can be carried out.

Furthermore, a method for manufacturing an electro-optical device according to the present invention is a method for manufacturing the electro-optical device, the brightness of light emitted from the plurality of electro-optical elements, or the focusing from the plurality of electro-optical elements. A lightness measurement step of measuring the brightness of light emitted through the transparent lens array in order along the lens arrangement direction, and light of the light transmitting member based on the measurement result obtained in the lightness measurement step A light transmittance setting step for setting the transmittance so as to vary stepwise or continuously in the lens arrangement direction, and a light transmissive member having the light transmittance set in the light transmittance setting step. And an assembling step for assembling the electro-optical panel and the converging lens array. According to such a method of manufacturing an electro-optical device, it is possible to easily and inexpensively produce a high-quality electro-optical device by eliminating problems such as unevenness in the density of an image caused by variations in brightness of the plurality of electro-optical elements. It becomes possible to provide.

Hereinafter, an electro-optical device, an image forming apparatus, and a method of manufacturing the electro-optical device according to the present invention will be specifically described based on the embodiments shown in the drawings. In the following drawings, the ratio of the dimensions of each part is appropriately changed from the actual one. In addition, as an electro-optical device in each of the following embodiments, it is used as a line-type optical head for forming an electrostatic latent image on an image carrier such as a photosensitive drum in an image forming apparatus using an electrophotographic method. This will be described as an example.

<First Embodiment>
Electro-optical device
FIG. 1 is a plan view showing an embodiment of an electro-optical device according to the present invention, and FIG. 2 is a side view of the electro-optical device. The electro-optical device 1 in the illustrated example includes a light-emitting panel (electro-optical panel) 2, a converging lens array 4, and a light transmission member 3 interposed between the light-emitting panel and the converging lens array 4. The light emitting panel 2 includes a light transmissive element substrate (array substrate) 22.
A light emitting element 21 as a plurality of electro-optical elements formed on the element substrate 22, and a sealing body 23 covering these light emitting elements 21. Light from each light emitting element 21 is transmitted to the element substrate 22. In this configuration, the light exits from the light exit surface (upper surface in the figure) S3.

Each of the light emitting elements 21 is an electro-optical element whose light emission characteristics are changed by applied electric energy. Specifically, the light emitting element 21 is excited by recombination of injected carriers and sandwiches the light emitting layer. The organic EL element has a pair of electrodes and emits light according to a voltage applied between the pair of electrodes. Of these pair of electrodes, the electrode on the element substrate 22 side is ITO.
It is a transparent electrode such as (Indium Tin oxide). The light emitting panel 2 is provided with wiring for applying a driving voltage to each light emitting element 21. The light emitting panel 2 may be provided with a circuit element (for example, TFT (thin film transistor)) for applying a driving voltage to each light emitting element 21.

The element substrate 22 is a flat plate made of a light-transmitting material such as glass or transparent plastic, and the light emitting elements 21 are arranged in a staggered pattern in one direction on the element substrate 22. A plane passing through 21 is a light emitting surface Q. The sealing body 23 is attached to the element substrate 22, and cooperates with the element substrate 22 to isolate the light emitting element 21 from the outside air, particularly moisture and oxygen, and suppress the deterioration thereof.

The converging lens array 4 transmits a part of the light incident on the light incident surface S2 and emits the light from the light emitting surface S1, and transmits the light traveling from the light emitting panel 2 so as to pass through the light emitting surface Q. A plurality of gradient index lenses 41 capable of forming an erect image with respect to an image (an image on the light emitting panel 2) are provided. The light incident surface S2 of the converging lens array 4 and the light emitting surface S3 of the light emitting panel 2 are opposed to each other, and the distance between the light emitting surface Q and the light emitting surface S3 depends on the thickness of the element substrate 22 and the light transmitting member 3.
It is approximately equal to the sum of the thicknesses. In the electro-optical device 1 as described above, the distance between the light emitting surface S1 and the imaging surface P is arranged so as to match the working distance on the image side of the converging lens array 4.

Each of the gradient index lenses 41 is arranged in a zigzag pattern in one direction (X direction) as shown in FIG. 1 and overlaps the region where the light emitting elements 21 of the light emitting panel 2 are formed. The images obtained by the plurality of gradient index lenses 41 constitute one continuous image. The light emitting element 21
And the arrangement pattern of the gradient index lens 41 is not limited to the illustrated form,
It may be a single row or three or more rows, or may be arranged in another suitable pattern.

The light transmitting member 3 is interposed between the light emitting panel 2 and the converging lens array 4 to keep the distance between them constant, and guides the light from the light emitting panel 2 to the converging lens array 4.
The lens 1 is configured as one or a plurality of layers in the optical axis direction. The light transmitting member 3 extends across the optical axis of each gradient index lens 41, and in the present embodiment, is formed in a substantially rectangular parallelepiped shape that is long in the X direction and is made of glass or transparent plastic. Then, the light emitted from the light emitting panel 2 is transmitted and guided to the converging lens array 4. Of the surface of the light emitting panel 2, the entire surface on the light emitting panel 2 side is in contact with the light emitting surface S3 of the light emitting panel 2, and the surface on the converging lens array 4 side is the surface of the light incident surface S2 of the converging lens array 4. The whole area touches.

In the present invention, the light transmittance of the light transmitting member 3, more specifically, the light transmittance in the optical axis direction of the lens 41, and the arrangement direction of the lens 41 and the light emitting element 21 (X direction in FIGS. 1 and 2). In the embodiment shown in the figure, the light transmitting member 3 is configured as one layer, and the light transmitting member 3 composed of the one layer has a plurality of longitudinal directions (the X direction). The portions 30a to 30c are divided into portions 30a to 30c having different light transmittances. Accordingly, it is possible to eliminate variations in brightness of the light emitting element 21 as a plurality of electro-optical elements or the combination of the element 21 and the converging lens array 4.

Specifically, for example, the brightness of light emitted from the light emitting elements 21 is A1 in FIG.
When there is a variation in the arrangement direction of the light emitting element 21 and the lens 41 (left and right direction in FIG. 3), that is, the X direction, the light transmittance of the light transmitting member 3 is set almost inversely proportional to the brightness. In this embodiment, as shown in FIG. 3, the central portion of the light emitting element 21 in the arrangement direction is bright and the brightness of both ends is lower than that of the central portion. The light transmittances of the portions 30a and 30c are set to a relatively high light transmittance a1, and the light transmittance of the central portion 30b is set to a light transmittance a2 lower than that.

Thereby, the light from the light emitting element 21 having the light brightness I _X1 in FIG.
And a light-emitting element having a light brightness I _Y1 and a light brightness I _X2 that are transmitted through the portion 30a of the light transmitting member 3 and the converging lens array 4 and projected onto the image forming surface of the image carrier 10 or the like. The brightness I _{Y2 of the} light projected from the element substrate 22, the portion 30a of the light transmitting member 3 and the converging lens array 4 and projected onto the imaging surface of the image carrier 10 or the like, It can be made almost equal. The relationship is shown in the following formulas (1) to (3). In the following formula, b is the element substrate 2
The light transmittance of 1 and s represent the light utilization rate of the converging lens array.

As described above, according to the present invention, by varying the light transmittance of the light transmissive member 3 in the arrangement direction of the lenses 41, it is possible to correct variations in brightness of the light emitting elements 21. In particular, the lens 4 of the light transmitting member 3 according to the brightness of the light emitting element 21 as in the above embodiment.
3 by changing (changing) the light transmittance in the arrangement direction of 1 stepwise.
1 can correct the brightness variation of the light-emitting element, and A2 in FIG. 2 is the corrected brightness, that is, a light transmitting member between the light-emitting panel 2 and the converging lens array 4 as shown in FIG. 3 represents the brightness on the imaging plane P with 3 interposed. It can be seen that there is less variation in brightness of A2 than A1.

In the above embodiment, the light transmittance of the light transmissive member 3 is changed stepwise, but may be changed continuously. Moreover, although the said embodiment corrected the variation in the brightness of the light emitting element 21, when the convergence lens array 4 also has the transmittance | permeability and the brightness variation, the light emitting element 21 and the convergent lens array 4 are used. You may make it vary the light transmittance of the light transmissive member 3 according to the variation in the brightness combined. Furthermore, when the light transmitting member 3 having a light transmittance as high as possible is used, the corrected brightness can be further increased.

As described above, the electro-optical device 1 includes the light-emitting panel 2 as the electro-optical panel having the light-emitting elements 21 as the plurality of electro-optical elements, and the light-emitting panel 2 that transmits light emitted from the light-emitting panel 2. A converging lens in which a plurality of gradient index lenses 41 capable of forming an erect image with respect to the upper image are arranged in one direction, and images obtained by the plurality of gradient index lenses 41 constitute one continuous image. An array 4 and a light transmitting member 3 disposed between the light emitting panel 2 and the converging lens array 4 and guiding the light emitted from the light emitting panel 2 to the converging lens array 4. By varying the light transmittance in the arrangement direction of the lenses 41, the brightness of the light-emitting elements 21 or the elements 21 including the converging lens array 4 is obtained.
Therefore, it is possible to easily correct variations in brightness.

[Method of manufacturing electro-optical device]
Next, the method for manufacturing the electro-optical device according to the present invention will be specifically described by taking the electro-optical device of the above embodiment as an example. Various methods are conceivable as a method for manufacturing the electro-optical device 1 according to the above embodiment. Here, two methods of the manufacturing method 1 and the manufacturing method 2 are illustrated.

<Manufacturing method 1>
In the manufacturing method 1, the light emission panel 2 and the light transmissive member 3 are manufactured first. In the manufacture of the light-emitting panel 2, a light-transmitting flat plate is used as the element substrate 22, and the light-emitting elements 21 made up of a plurality of EL elements are staggered in one direction (the X direction) as shown in FIG. Arrange. on the other hand,
In manufacturing the light transmitting member 3, first, the brightness of the light emitted from the plurality of light emitting elements 21 or the brightness of the light emitted from the plurality of light emitting elements 21 and transmitted through the converging lens array 4 is determined. taking measurement. In these measurements, measurement is performed sequentially or collectively along the arrangement direction (the X direction) of the light emitting elements 21 and the lenses 41 of the converging lens array 4.

When measuring the brightness of light emitted from the plurality of light emitting elements 21, the light emitted from the plurality of light emitting elements 21 is a member constituting the light emitting panel 2 (in the above embodiment, the element substrate). What is necessary is just to measure the brightness after passing 22). The plurality of light emitting elements 21
When measuring the brightness of the light emitted from the light and transmitted through the converging lens array 4, the light emitting element 21 and the converging lens array 4 are arranged in a predetermined assembly state, or both of them are the light of the lens 41. Measure in a state where they are arranged so as to overlap in the axial direction. Or a plurality of light emitting elements 2
The brightness of light emitted from 1 and the brightness, transmittance, or light attenuation rate of light transmitted through the converging lens array 4 are measured separately, and the plurality of light emitting elements 21 are based on the measurement results.
The brightness of the light transmitted through the converging lens array 4 may be obtained by calculation.

Next, when there is a variation in the X direction in the brightness based on the measurement result, the light transmittance of the light transmitting member 3 is made different accordingly, and the light transmission is performed as shown in FIG. When the member 3 is configured as one layer and its light transmittance is varied stepwise in the longitudinal direction (the X direction), the light transmitting member 3 is divided into a plurality of portions 30a-30 in the longitudinal direction.
Dividing into c, the length dimension and the light transmittance of each part 30a-30c are each determined, and each part which has the light transmittance according to it may be connected, and the light transmissive member 3 may be formed. In the present embodiment, as shown in FIG. 4A, a central portion 30 formed of a translucent material having a light transmittance a2.
On both sides of b, a light transmitting member 3 is formed by integrally fixing both end portions 30a and 30c formed of a light transmitting material having a light transmittance a1.

Next, the light transmitting member 3 is joined to the light emitting panel 2 as shown in FIG. This joint is
The entire area of one widest surface (lower surface in the figure) of the light transmitting member 3 is in contact with the light emitting surface S3 of the light emitting panel 2,
The entire region of the light emitting panel 2 in which the light emitting elements 21 are formed overlaps with the widest surface, and the longitudinal direction of the light transmitting member 3 and the arrangement direction of the light emitting elements 21 are matched. Next, as shown in FIG. 4B, the converging lens array 4 is joined to the widest surface (upper surface in the drawing) of the other light transmission member 3 (the side opposite to the light emitting panel 2). In this joining, the entire area of the light incident surface S2 of the converging lens array 4 is in contact with the other widest surface of the light transmitting member 3, and the arrangement direction (X direction) of the gradient index lens 41 of the converging lens array 4 This is performed so that the longitudinal direction of the light transmitting member 3 coincides with each other and each gradient index lens 41 overlaps the region where the light emitting element 21 of the light emitting panel 2 is formed.

Finally, the relative positions of the light emitting panel 2, the light transmitting member 3, and the converging lens array 4 are fixed. The fixing method is arbitrary. For example, the side surfaces (upper and lower surfaces) of the light transmitting member 3 may be bonded to the light emitting panel 2 and the converging lens array 4, or the light emitting panel 2 and the converging lens array 4 may be bonded. The light emitting panel 2, the light transmitting member 3, and the converging lens array 4 may be accommodated in a case that is biased toward the light transmitting member 3.

<Manufacturing method 2>
In the manufacturing method 2, the manufacture of the light-emitting panel 2 and the measurement of the variation are the same as those in the manufacturing method 1, and the light transmittance of the light transmitting member 3 is also different based on the measurement result.
In particular, as described above, the light transmitting member 3 composed of one layer is divided into a plurality of parts in the longitudinal direction, and the length dimension and light transmittance of each part are determined in the same manner as described above. And in the said manufacturing method 2, the center part 30b is first formed with the translucent material of the light transmittance a2, and the said translucent material is directly mounted on the light emission panel 2, and the said center part 30b is formed. Alternatively, a separately formed one may be placed on the light emitting panel 2.

In FIG. 5A, the central portion 30b of the light transmittance a2 formed in a substantially rectangular parallelepiped shape in advance is shown in the light emitting panel 2.
The converging lens array 4 is placed thereon and placed thereon. The portion 30a, the light emitting panel 2, and the converging lens array 4 are joined in a state of being in close contact with each other. Next, FIG.
As shown in (b), between the light emitting panel 2 and the converging lens array 4 on both sides of the portion 30b,
A transparent light-transmitting material having a light transmittance a1 that also serves as an adhesive is injected and cured to form a portion 30a.
And 30c are formed. In addition, while preventing outflow of the fluid translucent material,
A guide frame or the like may be used to shape the portions 30a and 30c into a desired shape.

<Second Embodiment>
Next, an electro-optical device according to a second embodiment of the invention will be described. In the electro-optical device 1 of the present embodiment, the light transmission member is configured in a multilayer structure in which a plurality of layers are stacked in the optical axis direction of the lens, and light transmission of at least one of these layers, that is, two layers in the present embodiment. The rate is different. Hereinafter, the difference from the first embodiment will be mainly described in detail.

Electro-optical device
FIG. 6 is a side view (elevated view) of the electro-optical device according to the second embodiment of the present invention. The electro-optical device 1 of the present embodiment is different from the embodiment of FIG. 2 in that the light transmission member 3 is composed of one layer, whereas the light transmission member 3 of the present embodiment has a plurality of layers. It is a point comprised by the layer, and in the case of a figure, it is comprised by the three layers 31-33. The light transmissive member 3 is a member that is filled between the light emitting panel 2 and the converging lens array 4 so as to have a uniform distance therebetween, and extends across the optical axis of each gradient index lens 41. It is composed of a plurality of light-transmitting layers 31 to 33 and transmits light traveling from the light emitting panel 2.

The layer 31 is an intermediate layer having an equal thickness interposed between the layer 32 and the layer 33. In this embodiment, the layer 31 is formed of glass or transparent plastic, and the light transmittance of the layer 31 is a3 and is kept constant over the entire length. I'm leaning. The entire surface of the layer 31 on the light emitting panel 2 side is bonded to the entire surface of the layer 32 on the side of the converging lens array 4, and the entire surface of the layer 31 on the side of the converging lens array 4 is bonded to the layer 33. Are joined to the entire surface of the light emitting panel 2 side.

The layer 32 serves as an adhesive having an equal thickness sandwiched between the layer 31 and the light emitting panel 2, and includes a plurality of rectangular parallelepiped portions 32 a to 32 c that are continuous in the X direction. The portion 32b has a light transmittance of a.
5 is formed of a translucent material that also serves as a transparent adhesive, and the portions 32a and 32c are each formed of a translucent material that also serves as a transparent adhesive having a light transmittance of a4.

The layer 33 is also a layer serving as an adhesive of equal thickness sandwiched between the layer 31 and the converging lens array 4.
It is composed of a plurality of rectangular parallelepiped portions 33a to 33b that are continuous in the direction. The portion 33a is formed of a translucent material that also serves as a transparent adhesive having a light transmittance of a6, and the portion 33b is formed of a translucent material that also serves as a transparent adhesive having a light transmittance of a7. .

The lengths and light transmittances in the X direction of the portions 32a to 32c and 33a to 33b of the layer 32 and the layer 33 are the brightness of the plurality of light emitting elements 21 or the convergence property of the light emitting elements 21 as described above. The brightness in the state where the light emitting panel 2, the light transmissive member 3, and the converging lens array 4 are assembled as shown in FIG. 6 is set as appropriate according to the combined brightness of the lens array 4. Is made almost constant.

The relationship will be described using mathematical formulas. Light emitted from the light emitting element 21 having a predetermined brightness _IX in FIG. 6 is transmitted through the element substrate 22, the multiple layers of the light transmitting member 3 and the converging lens array 4. Assuming that the brightness of light when imaged on the imaging surface is I _Y , the I _Y can be expressed as the following formula (4). In the formula, a, b, c, d,...
1 is a light transmittance of a member through which light from 1 is sequentially transmitted, and s represents a light utilization rate of the converging lens array 4.

In addition, the light transmittance a in the above formula (4) can be expressed as the following formula (5). Α in the equation (5) is an absorption coefficient and is a value unique to the substance, and the α can be expressed as the following equation (6). In Equation (6), k is an extinction coefficient and is a value unique to the substance, and λ represents the wavelength of light. The same applies to the other light transmittances b, c, d.

In the present embodiment, the light transmittance of the layer 32 and the layer 33 of the light transmitting member 3 is partially made different so that the light is emitted from all the light emitting elements 21 and imaged on the imaging surface. The light brightness I _Y is made to be substantially constant. Thereby, even when the brightness of light from the light emitting elements 21 including the light emitting elements 21 or the converging lens array 4 varies, the brightness in the X direction can be made substantially constant. is there.

As is clear from the above description, the same effects as those of the first embodiment can be obtained in this embodiment. Further, when the light transmissive member 3 is formed of a plurality of layers 31 to 33 as in the present embodiment, and when the two or more layers are divided into a plurality of portions and the light transmittance of each portion is made different, more It is possible to obtain various types of light transmittance distributions, and to correct the variation in brightness more finely.

In the above embodiment, the two layers 32 depend on the brightness of light emitted from the plurality of light emitting elements 21 or the brightness of light emitted from the plurality of electroluminescent elements 21 and transmitted through the converging lens array 4. However, only one of them or three or more layers may have different light transmittance distributions. Further, when the light transmittance of the light transmitting member 3 is made different according to the brightness of the light emitted from the plurality of electroluminescent elements 21 and transmitted through the converging lens array 4, the light emitted from the plurality of electroluminescent elements 21. The brightness variation of the focusing lens array 4 is corrected by any layer (for example, the layer 33), and the brightness, light transmittance or light absorption rate variation of the converging lens array 4 may be corrected by another layer (for example, the layer 32). it can. Further, the number of layers, the number of layers to be divided, and the number of parts to be divided can be changed as appropriate.

[Method of manufacturing electro-optical device]
Next, a manufacturing method in the case where the light transmissive member 3 is formed of a plurality of layers will be described by taking the electro-optical device 1 in the second embodiment as an example. Various methods can be considered for the method of manufacturing the electro-optical device in the second embodiment, but one manufacturing method is illustrated here.

First, the light emitting panel 2 and the layer 31 are manufactured. The layer 31 is formed in a predetermined size with a translucent material such as glass or transparent plastic. As the light-transmitting material, it is preferable to use a material having as high a light transmittance as possible so that the brightness does not decrease. In this embodiment, the light transmittance is a3 and constant over the entire length as described above. Has been.

Then, as shown in FIG. 7 (a), the translucent material that also serves as a transparent adhesive having a light transmittance of a5 is coated on the installation position of the portion 32b on the light emitting surface S3 of the light emitting panel 2, The translucent material is sandwiched between the light emitting panel 2 and the layer 31 and compressed until a predetermined thickness is obtained. By curing in this state, a portion 32b is formed as shown in FIG.
The light emitting panel 2 and the layer 31 are bonded via b. Next, as shown in FIG. 4B, a light-transmitting material that also serves as a transparent adhesive having a light transmittance of a4 is injected between the light-emitting panel 2 and the layer 31 on both sides of the portion 32b, and cured. Let the portion 32a and the portion 32c as shown in FIG.
And form.

Next, as shown in FIG. 7C, the light transmission for forming the portion 33b on the surface (upper surface) opposite to the light emitting panel 2 of the layer 31 also serves as a transparent adhesive having a7. Coated with sex material,
The translucent material is sandwiched between the layer 31 and the converging lens array 4 and compressed to a predetermined thickness. By curing in this state, a portion 33b is formed as shown in FIG. 4D, and the layer 31 and the converging lens array 4 are bonded via the portion 33b. Next, a translucent material serving as a transparent adhesive having a light transmittance of a6 is injected between the layer 31 on the side of the portion 33b and the converging lens array 4, and the portion is cured to form the portion 33a. do it.

In the step of coating or injecting the translucent material also serving as the adhesive, the flowable translucent material is prevented from flowing out and the portion formed of the translucent material is predetermined. A guide frame or the like may be used to form the shape. In addition, when forming the portion by compressing the translucent material, a ball-shaped or other desired shape gap securing material having a predetermined diameter is used so that the portion is accurately formed to a predetermined thickness. The light-transmitting material may be interposed between the members to be compressed, or may be mixed in the light-transmitting material. In addition, as said gap ensuring material, what has a translucency and has a light transmittance substantially equivalent to the said translucent material is preferable.

As described above, the electro-optical device as shown in FIG. 6 is easily and reliably manufactured by interposing the light transmitting member 3 of the plurality of layers 31 to 33 between the light emitting panel 2 and the converging lens array 4. Is something that can be done. In addition, when changing the number of layers of the light transmissive member 3, the number of layers having different light transmittances, the arrangement of parts, and the like as described above, the above-described process may be appropriately changed accordingly.

[Image forming apparatus]
The electro-optical device according to each of the embodiments of the present invention can be used as a line-type optical head for writing a latent image on an image carrier in an image forming apparatus using an electrophotographic method. Examples of such an image forming apparatus include a printer, a printing part of a copying machine, and a printing part of a facsimile.

FIG. 8 is a longitudinal sectional view of the image forming apparatus according to the embodiment of the present invention. This image forming apparatus
This is a tandem type full-color image forming apparatus using a belt intermediate transfer body system. In this image forming apparatus, four optical heads 10K, 10C, 10M, and 10Y having the same configuration are exposed positions of four photosensitive drums (image carriers) 110K, 110C, 110M, and 110Y having the same configuration. Respectively. The optical heads 10K, 10C, 10M, and 10Y use the electro-optical device according to the embodiment of the present invention.

As shown in the figure, this image forming apparatus is provided with a driving roller 121 and a driven roller 122, and an endless intermediate transfer belt 120 is wound around the rollers 121 and 122.
The intermediate transfer belt 120 is rotationally driven at a predetermined speed in the direction of the arrow in the drawing by the rotation of the driving roller 121. Although not shown, tension applying means such as a tension roller for applying tension to the intermediate transfer belt 120 may be provided as appropriate.

Around the intermediate transfer belt 120, there are four photosensitive drums 1 having photosensitive layers on the outer peripheral surface.
10K, 110C, 110M, and 110Y are arranged at a predetermined interval from each other, and each of the photosensitive drums 110K, 110C, 110M, and 110Y is rotationally driven in synchronization with the driving of the intermediate transfer belt 120. Note that the subscripts K, C, M, and Y of the symbol of the photosensitive drum mean that they are used to form black, cyan, magenta, and yellow images, respectively. In the following, the above codes are expressed as “110 (K, C, M, Y)” by enclosing them in common terms. The same applies to other devices and members described later.

Around each of the photosensitive drums 110 (K, C, M, Y), a corona charger 111 (K,
C, M, Y), optical head 10 (K, C, M, Y), and developer 114 (K, C, M, Y)
Is arranged. Corona charger 111 (K, C, M, Y) corresponds to the corresponding photosensitive drum 1.
The outer peripheral surface of 10 (K, C, M, Y) is uniformly charged. Optical head 10 (K, C, M, Y)
Writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum. Each optical head 10 (K,
C, M, Y) indicates that the arrangement direction of the plurality of light emitting elements 21 is the photosensitive drum 110 (K, C, M, Y).
) Along the bus (in the main scanning direction). The electrostatic latent image is written by irradiating the photosensitive drum with light by the plurality of light emitting elements 21 described above. Developer 114 (K, C
, M, Y) forms a visible image, ie, a visible image, on the photosensitive drum by attaching toner as a developer to the electrostatic latent image.

Black, cyan, magenta, and black formed by such a four-color single color image forming station
The yellow visible images are sequentially primary-transferred onto the intermediate transfer belt 120 to be superimposed on the intermediate transfer belt 120, and as a result, a full-color visible image is obtained. Inside the intermediate transfer belt 120, four primary transfer corotrons (transfer units) 112 (K, C, M, Y) are provided.
Is arranged. The primary transfer corotron 112 (K, C, M, Y) is connected to the photosensitive drum 11.
0 (K, C, M, Y) are arranged in the vicinity of the photosensitive drum 110 (K, C,
The visible image is electrostatically attracted from (M, Y) to transfer the visible image to the intermediate transfer belt 120 passing between the photosensitive drum and the primary transfer corotron.

A sheet 102 such as paper as a target for finally forming an image is picked up by the pickup roller 10.
3, the sheet is fed one by one from the sheet feeding cassette 101 and is fed to the nip between the intermediate transfer belt 120 and the secondary transfer roller 126 in contact with the driving roller 121. The full-color visible image on the intermediate transfer belt 120 is secondarily transferred to one side of the sheet 102 by the secondary transfer roller 126 and fixed on the sheet 102 through the fixing roller pair 127 as a fixing unit. . Thereafter, the sheet 102 is discharged onto a paper discharge cassette formed in the upper part of the apparatus by a paper discharge roller pair 128. According to each of the image forming apparatuses described above, since the electro-optical device according to the embodiment of the present invention is used as the optical head, a high quality image can be formed.

The image forming apparatus to which the electro-optical device according to each of the embodiments of the invention can be applied has been described above. However, the electro-optical device according to each of the embodiments may be applied to other electrophotographic image forming apparatuses other than the above. Applicable. For example, a rotary development type full-color image forming apparatus that uses a belt intermediate transfer body method, an image forming apparatus that directly transfers a visible image from a photosensitive drum to a sheet without using an intermediate transfer belt, and a monochrome image The present invention can also be applied to an image forming apparatus that forms the image.

In each of the above-described embodiments, the bottom emission type light emitting panel 2 in which light emitted from each light emitting element 21 passes through the element substrate 22 and is emitted from the light emitting panel 2 is used. A top emission type light-emitting panel that emits light in the direction may be used. That is, the sealing body 23 may be an object that transmits light traveling from a plurality of electro-optical elements (light emitting elements). In this case, a material having translucency is used as a material of each part so that light emitted from each light emitting element and traveling to the sealing body side is not blocked.

In each of the above-described embodiments, an organic EL element that requires excitation by recombination of carriers is employed as the plurality of electro-optical elements whose light emission characteristics or light transmission characteristics change depending on applied electric energy. Light-emitting elements that do not require recombination of carriers (for example, inorganic E
L element), a light emitting element that does not require excitation (for example, an inorganic LED), a light valve element (for example, a liquid crystal element) whose light transmission characteristics are changed by applied electric energy, and the like may be employed.

FIG. 2 is a plan view showing an embodiment of an electro-optical device according to the invention. FIG. 3 is a side view of the electro-optical device. The graph which shows the relationship between the arrangement direction of a light emitting element, and a brightness. Explanatory drawing which shows an example of the manufacturing process of the said electro-optical apparatus. Explanatory drawing which shows the other example of the manufacturing process of the said electro-optical apparatus. FIG. 6 is a side view showing another embodiment of the electro-optical device according to the invention. Explanatory drawing which shows an example of the manufacturing process of the said electro-optical apparatus. 1 is a longitudinal sectional view showing an embodiment of an image forming apparatus according to the present invention. 1 is a perspective view of a conventional electro-optical device applied to an image forming apparatus. The side view of the conventional electro-optical apparatus. The perspective view which shows schematic structure of a convergent lens array. 6 is a graph showing a relationship between a light emitting element and brightness in a conventional electro-optical device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electro-optical apparatus, 2 light emission panel (electro-optical panel), 21 ... Light emitting element (electro-optical element), 22 ... Element board | substrate, 23 ... Sealing body, 3 ... Light transmission member, 30-33 ... Layer, 4 ... Convergent lens array, 41... Gradient index lens, 10, 110... Image carrier (photosensitive drum).

Claims (6)

An electro-optical panel having a plurality of electro-optical elements whose light emission characteristics or light transmission characteristics are changed by given electric energy, and emitting light from each of the plurality of electro-optical elements;
A plurality of gradient index lenses that transmit light emitted from the electro-optical panel and can form an erect image with respect to the image on the electro-optical panel are arranged in a direction perpendicular to the optical axis direction of the lens,
A converging lens array in which images obtained by the plurality of lenses constitute one continuous image;
A light transmissive member interposed between the electro-optical panel and the converging lens array and guiding light emitted from the electro-optical panel to the converging lens array;
An electro-optical device, wherein the light transmittance of the light transmissive member is varied in the lens arrangement direction. 2. The light transmissive member has a structure in which one or more layers are laminated in the optical axis direction of the lens, and the light transmittance of the light transmissive member of at least one layer is made different in the arrangement direction of the lenses. The electro-optical device according to 1. The light transmittance of the light transmissive member depends on the brightness of light emitted from the plurality of electro-optic elements or the brightness of light emitted from the plurality of electro-optic elements and transmitted through the converging lens array. The electro-optical device according to claim 1, wherein the electro-optical device is made different. The light transmittance of the light transmitting member is approximately equal to the brightness of light emitted from the plurality of electro-optic elements, or the brightness of light emitted from the plurality of electro-optic elements and transmitted through the converging lens array. The electro-optical device according to claim 1, wherein the electro-optical device is varied in inverse proportion. An image carrier;
A charger for charging the image carrier;
The electro-optical device according to claim 1, wherein light that travels from the electro-optical panel and passes through the converging lens array is irradiated onto a charged surface of the image carrier to form a latent image. Equipment,
A developing unit that forms a visible image on the image carrier by attaching toner to the latent image; and
An image forming apparatus comprising: a transfer unit that transfers the visible image from the image carrier to another object. A method for manufacturing the electro-optical device according to claim 1,
The brightness of light emitted from the plurality of electro-optic elements or the brightness of light emitted from the plurality of electro-optic elements through the converging lens array is sequentially measured along the lens arrangement direction. Brightness measurement process to
A light transmittance setting step for setting the light transmittance of the light transmitting member based on the measurement result obtained in the lightness measurement step so as to be stepwise or continuously different in the arrangement direction of the lenses,
An assembling step for assembling the light transmissive member having the light transmittance set in the light transmittance setting step in a state of being interposed between the electro-optical panel and the converging lens array. A method for manufacturing an electro-optical device.

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