JP2007276254A - Exposing device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposing device which can form a clearer image, and to provide an image forming device utilizing the exposing device. <P>SOLUTION: This exposing device is equipped with a plurality of light emitting elements 21 which are arranged in one direction, and is equipped with a light emitting panel 20 which emits light from the light emitting elements 21. Also, the exposing device is equipped with a focusing type lens array 40. In this case, the focusing type lens array 40 has a plurality of refractive rate distribution type lenses 41 which can form an upright real image by permeating a part of the light, which has been emitted from the light emitting panel 20 and has entered. By the focusing type lens array 40, the image formed by the refractive rate distribution type lenses 41 constitutes one continuous image. Also, the exposing device is equipped with an opening section 30 which is inserted between the light emitting panel 20 and the focusing type lens array 40, is formed of a member which bars the rectilinear propagation of the incident light. On the member, a plurality of openings 31 which respectively make a part of the light emitted from the plurality of light emitting elements 21 pass through are formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an exposure apparatus including a plurality of light emitting elements and an image forming apparatus using the exposure apparatus.

Conventionally proposed is an image forming apparatus that forms a latent image (electrostatic latent image) by selectively exposing an image forming surface (photosensitive surface) of an image carrier such as a pre-charged photosensitive drum by a plurality of light emitting elements. Has been. As an exposure apparatus used in this image forming apparatus, an EL (Electro L) is used as a light emitting element.
One having an uminescent element (see Patent Document 1) and one having a focusing lens array as an imaging optical system (see Patent Document 2) are known. The focusing lens array is, for example,
SLA (Selfoc Lens Array) available from Nippon Sheet Glass Co., Ltd. (Selfoc \ SELFOC is a registered trademark of Nippon Sheet Glass Co., Ltd.).
JP 59-214672 A JP-A-11-231212

When an exposure apparatus including an EL element and a converging lens array is used in an image forming apparatus,
The image formed on the image forming surface of the image carrier becomes unclear. That is, the image on the image forming surface is blurred.
Therefore, the present invention provides an exposure apparatus capable of forming a clearer image and an image forming apparatus using the exposure apparatus.

An exposure apparatus according to the present invention includes a plurality of light emitting elements arranged along one direction, a light emitting apparatus that emits light from the plurality of light emitting elements, and one of light emitted from the light emitting apparatus and incident. A converging lens having a plurality of gradient index lenses capable of forming an erecting equal-magnification real image through a portion, and an image formed by the plurality of gradient index lenses forming one continuous image An array, a member interposed between the light emitting device and the converging lens array, and formed of a member that prevents the straight light of the incident light from traveling. And an opening having a plurality of openings to be passed therethrough.
Here, the “light emitting element” means an element in which a solid light emitting layer that emits light upon receiving electric energy is sandwiched between electrodes. As the light emitting element, OLED, inorganic EL element, inorganic LED (Li
ght Emitting Diode). OLED is organic EL (Electro Lumin
Also called escent element. That is, the OLED and the inorganic EL element are both types of EL elements. In this specification, an “EL element” refers to an element that emits light through excitation of excitons. On the other hand, both inorganic LEDs and OLEDs are types of LEDs. In this specification, “LED
"Refers to a carrier injection type device that emits light through recombination of electrons and holes. Examples of the member that prevents the incident light from going straight include a member that blocks incident light by absorption, a member that blocks incident light by reflection, and a member that refracts incident light.
By the way, the converging lens array has an image formed on the image forming surface by using light passing through the gradient index lens near the light emitting element among the light emitted from the light emitting element and the light emitted from the light emitting element. There is a tendency that an image formed by using light passing through a gradient index lens far from the light emitting element is greatly deviated from the incident light. This tendency is a cause of blurring of the image on the image forming surface.
On the other hand, in the above exposure apparatus (first exposure apparatus), one of the lights emitted from each of the plurality of light emitting elements in the opening portion interposed between the light emitting apparatus and the converging lens array. Part of the light passes through the opening corresponding to the light emitting element, and other light is prevented from traveling straight. Therefore, according to the above-described exposure apparatus, by appropriately designing the aperture, the light used for forming one continuous image can be converted into a refractive index distribution near the light emitting element among the light emitted from the light emitting element. It can be limited to only light passing through the mold lens. Therefore, according to the exposure apparatus, a clearer image can be formed.

In the above exposure apparatus, each of the plurality of openings may have a length longer than a diameter of the opening on the converging lens array side. Exposure apparatus of this aspect (second exposure apparatus)
According to the above, the above-described effect can be obtained more reliably.

Each of the above-described exposure apparatuses may include a transparent member that is in contact with the light emitting device and the converging lens array and that is present to fill a gap between the light emitting device and the converging lens array. This gap also includes the opening described above. In the exposure apparatus of this aspect, there is no solid-gas interface on the optical path of the light emitted from the light emitting element and incident on the converging lens array. Therefore, reflection at the interface is suppressed, and light utilization efficiency is improved.

In the first or second exposure apparatus, each of the plurality of light emitting elements has a light emitting surface that emits light, and each light incident surface of the plurality of gradient index lenses is formed of the converging lens array. A part of the end face on the light emitting device side is formed, the opening has a plate shape, and each of the plurality of openings has a substantially circular shape on the converging lens array side, and the opening of the converging lens array A substantially circular range in which light from the light emitting element corresponding to the opening reaches the end surface on the light emitting device side is defined, the working distance on the object side of the converging lens array is L ₀ , and each of the plurality of openings The diameter on the converging lens array side is R1, the diameter or maximum width of the light emitting surface is R, the diameter of each of the plurality of gradient index lenses is d, and the diameter of each of the plurality of gradient index lenses is Diameter of said range against When the ratio was alpha, each of length t of the plurality of openings,
It may be expressed by the formula (1) with an error range of ± 10%. According to the exposure apparatus of this aspect, since trial and error for determining R1 and t are not required, the design is facilitated.

In the exposure apparatus of this aspect, the ratio of the diameter of the range to the diameter of each of the plurality of gradient index lenses may be 2.25 or more and 2.75 or less. According to the exposure apparatus of this aspect, since the various effects described above can be obtained using a general converging lens array that is widely distributed, manufacture is facilitated.

In each of the exposure apparatuses described above, the whole or the surface of the member forming the opening may be made of a light absorbing material. Examples of the light-absorbing material include materials having high light absorption such as metal and carbon. In the exposure apparatus of this aspect, reflected light and transmitted light from the opening can be reduced. Therefore, according to this aspect, it is possible to reduce the possibility that the light emitted from the light emitting device and entering the opening is used for forming one continuous image. That is, a clear image can be formed more reliably.

The present invention also provides an image carrier, a charger for charging the image carrier, and a latent image is formed by irradiating the charged surface of the image carrier with light from the exposure apparatus. There is provided an image forming apparatus comprising: each exposure device; and a developing unit that forms a visible image by attaching toner to the latent image, and transferring the visible image to another object. According to this image forming apparatus, since each of the exposure apparatuses described above is used, a clearer image can be formed.

Embodiments of the present invention will be described with reference to the drawings. In the following drawings,
The ratio of the dimensions of each part is made different from the actual one for convenience.

<Exposure device>
FIG. 1 is a perspective view showing an outline of an exposure apparatus 10 according to an embodiment of the present invention. The exposure apparatus 10 includes an outer peripheral surface (image forming surface) of the photosensitive drum 110 in the electrophotographic image forming apparatus.
110a is used as a line-type optical head that irradiates light to write a latent image.

The exposure apparatus 10 includes a light emitting panel (light emitting apparatus) 20 that emits light from a light source, a converging lens array 40 interposed between the light emitting panel 20 and the photosensitive drum 110, and the light emitting panel 20.
And a plate-like opening 30 having a thickness t interposed between the focusing lens array 40 and the focusing lens array 40. The opening 30 is bonded to the light converging lens array 40 side of the light emitting panel 20.

FIG. 2 is a plan view of the light emitting panel 20 and the opening 30, and FIG. 3 is a focusing lens array 4.
4 is a perspective view showing the configuration of 0, FIG. 4 is a plan view of the exposure apparatus 10, and FIG.
FIG. FIG. 5 is also a cross-sectional view taken along line AA of FIG. As shown in FIG. 2 and FIG.
The light emitting panel 20 includes a plurality of light emitting elements 21. Each light emitting element 21 is a light source that emits surface light, and has a substantially circular light emitting surface 21a having a diameter R. The light emitting surfaces 21a of the plurality of light emitting elements 21 are:
It almost coincides with the same plane. In the present embodiment, an OLED is employed as the light emitting element 21. Therefore, although not shown, the light emitting element 21 includes a light emitting layer formed of an organic EL material, and one electrode and the other electrode sandwiching the light emitting layer. The diameter (R) of the light emitting surface 21 a is also the diameter of the light emitting element 21. The shape of the light emitting surface does not have to be a circle, and may be an ellipse or a rectangle. In that case, the maximum width of the light emitting surface may be the diameter R.

The light emitting panel 20 includes a flat light source substrate (not shown). The plurality of light emitting elements 21 are arranged in a staggered pattern in two rows on the light source substrate along a direction substantially parallel to the rotation axis of the photosensitive drum 110. In addition, this Embodiment is deform | transformed and the arrangement pattern of the several light emitting element 21 is good also as a single row, and good also as three or more rows. The light emitting panel 20 includes a sealing layer (not shown) that covers the plurality of light emitting elements 21 and protects from the outside air. That is, each light emitting element 21 is sandwiched between the light source substrate and the sealing layer.

Even if the light emitting panel 20 is of a top emission type in which light from each light emitting element 21 is transmitted through the sealing layer, the bottom emission in which light from each light emitting element 21 is transmitted through the light source substrate is emitted. It may be of a type. In the case of the top emission type, one electrode (electrode on the sealing layer side) and the sealing layer are formed from a material having a high light transmittance. In the case of the bottom emission type, the other electrode (light source substrate side) Electrode) and the light source substrate are formed of a material having a high light transmittance.

In the light emitting layer of each light emitting element 21, the position of the light emitting surface 21a is arbitrary. However, here, in the case of the top emission type, a part of one end face (end face on the sealing layer side) of the light emitting layer becomes the light emitting face 21a, and in the case of the bottom emission type, the other end face of the light emitting layer. It is assumed that a part of (the end surface on the light source substrate side) becomes the light emitting surface 21a, and the following description will be made accordingly.

The opening 30 is formed of a light-absorbing member, and a plurality of openings 31 through which a part of light emitted from the plurality of light emitting elements 21 passes is formed. The opening 31 can be formed, for example, by etching or punching a light absorbing member such as a metal or a light shielding film. Each opening 31 has a cylindrical shape with a diameter R1 and penetrates in the thickness direction of the opening 30. The length (depth) of the opening 31 matches the thickness (t) of the opening 30. Multiple openings 3
The one and the plurality of light emitting elements 21 correspond one-to-one, and the central axes of the openings 31 and the light emitting elements 21 corresponding to each other substantially coincide with each other. Note that the present embodiment may be modified so that the shape of each opening 31 may be a rotating body (for example, a truncated cone) other than a cylinder. In that case, the diameter of the aperture 31 on the converging lens array 40 side is R1.

As shown in FIGS. 1 and 3 to 5, the converging lens array 40 is a long member including a plurality of gradient index lenses (GRIN lenses) 41 that connect real images, Side (light emitting panel 20 side) end surface 40a and image surface side (photosensitive drum 110 side) end surface 40b. The plurality of gradient index lenses 41 each have a central axis (optical axis) on the light emitting surface 2.
They are arranged in two rows and zigzag along the longitudinal direction of the converging lens array 40 (the direction of the rotation axis of the photosensitive drum 110) in a posture that is oriented substantially perpendicular to 1a. It should be noted that the present embodiment may be modified so that the arrangement pattern of the plurality of gradient index lenses 41 may be a single row or three or more rows.

Each gradient index lens 41 has a cylindrical shape, and the refractive index is distributed so that the lower the distance from the central axis toward the peripheral edge, the lower the cross section. Further, each gradient index lens 41
Each of the flat end faces is a part of the end face 40a or the end face 40b, and transmits a part of the light emitted from the light emitting panel 20 and incident on one end face (a part of the end face 40a). Injected from the other end surface (a part of the end surface 40b).

The converging lens array 40 has an ideal distance for allowing an erecting equal-magnification image of an object (light source) to be connected to the image plane as a real image, that is, an ideal image for enabling optimum image formation. A distance is defined. Hereinafter, this distance is referred to as “working distance”. The working distance includes the object and the end face 4
The object-side working distance (L ₀ ) between 0a and the image-side working distance (L
₁ ). In this embodiment, both the distance between the light emitting surface 21a and the end face 40a of the plurality of light emitting elements 21 matches the L _0, the distance between the end surface 40b and the outer peripheral surface 110a coincides with the L _1. Therefore, each of the plurality of gradient index lenses 41 can form an erecting equal-magnification image of the image on the light emitting panel 20 on the outer peripheral surface 110a. These erecting equal-magnification images are real images that form one continuous image (latent image).

The working distance is determined on the assumption that light emitted from an object and incident on the gradient index lens 41 passes only in the air. However, actually, the light emitting surface 21a and the end surface 40a.
Between them, there is a sealing layer or a light source substrate. Further, as will be described in detail later, in the modification of this embodiment, the space between the light emitting panel 20 and the converging lens array 40 may be filled with a transparent member. In this case, assuming that the refractive index of the light source substrate or the sealing layer is n1, the thickness of the light source substrate or the sealing layer is d1, the refractive index of the transparent member is n2, and the thickness of the transparent member is d2, the distance of the portion that passes through the air Can be described as L ₀ = d1 / n1 + d2 / n2 + La.

As the converging lens array 40, a general one that is widely distributed can be adopted.
For example, the length of each gradient index lens 41 is about 4.3 mm, the refractive index at the central axis of each gradient index lens 41 is 1.63, and the refractive index at the periphery of each gradient index lens 41 is A converging lens array such as 1.586 can be employed. Normally, L ₀ = L ₁
However, it is also possible to employ a converging lens array where L ₀ = L ₁ is not satisfied.

The central axis of the array of the plurality of light emitting elements 21, the central axis of the array of the plurality of apertures 31, and the central axis of the array of the plurality of gradient index lenses 41 are substantially parallel to each other and substantially perpendicular to the light emitting surface 21a. Overlapping in the direction. The length of each of the plurality of openings 31 is the same as the opening 31.
Longer than the diameter of the converging lens array 40 side.

For each opening 31, the opening 30 corresponds to the light emitting element 2 corresponding to the opening 31 on the end surface 40a.
The range from which the light from 1 reaches is limited. An example of this limitation is shown in FIG. 6 shows the end face 4
A part of 0a is schematically shown, and the center point P of one light emitting surface 21a and seven gradient index lenses 41 are shown. Any of these seven gradient index lenses 41 can transmit most of the light from the light emitting surface 21a when the opening 30 is not present. Of the seven gradient index lenses 41, the closest to the center point P is the gradient index lens 411, the next closest is the two gradient index lenses 412, 412, and the next closest. Are the two gradient index lenses 413 and 413, and the next closest are the two gradient index lenses 414 and 414.

In the present embodiment, since the opening 30 exists, the light emitting element 21 in the end face 40a.
A substantially circular range S in which light from the light reaches is as shown in the figure. In the figure, d is the diameter of each gradient index lens 41, and α · d is the diameter of the range S. α is the ratio of the diameter of the range S to the diameter of each gradient index lens 41, and is a constant determined according to the converging lens array 40 to be employed. In the example of this figure, α = 2.5, and the gradient index lens 41 that can transmit most of the light from the light emitting element 21 is a gradient index lens 411 and a gradient index lens 412. , 412, and gradient index lenses 413, 413 only.

In order to realize the above-described limitation, in this embodiment, the dimensions of the respective parts are determined so as to satisfy Equation (1) with an error range of ± 10%. The reason why the above-described limitation becomes possible by determining the dimensions of the respective parts so as to satisfy Expression (1) will be described with reference to FIG. FIG. 7 shows one light emitting element 21, one opening 31 of the opening 30, and an end surface 40 a of the converging lens array 40.

In FIG. 7, the length (t) of each opening 31 matches the distance between the light emitting surface 21 a and the end of the opening 30 on the converging lens array 40 side. This is because the illustration of the sealing layer or the light source substrate is omitted for simplification.

In FIG. 7, θ is an angle formed by a traveling direction of a certain kind of light and a direction perpendicular to the light emitting surface 21a. The certain kind of light is light that is emitted from the periphery of the light emitting surface 21a, passes through the edge of the aperture 31 on the converging lens array 40 side, and reaches the end surface 40a. The traveling direction of light is a direction parallel to a straight line connecting the two points when the light passes through the two points.

As is clear from FIG. 7, the diameter (α · d) of the range S is expressed by Expression (2), and the diameter (R1) of the opening 31 is expressed by Expression (3). Then, Equation (1) is obtained by simultaneously solving Equation (2) and Equation (3). Therefore, if the dimensions of the respective parts are determined so as to satisfy Expression (1), the above-described limitation can be realized.

In the exposure apparatus 10 according to the present embodiment, a part of the light emitted from the light emitting element 21 of the light emitting panel 20 in the opening 30 interposed between the light emitting panel 20 and the converging lens array 40. Light passes through the opening 31 and other light is prevented from traveling straight. That is, the exposure apparatus 10
According to the above, light that is used to form one continuous image on the outer peripheral surface 110 a out of the light emitted from each light emitting element 21 is transmitted through the gradient index lens 41 near the light emitting element 21 ( The light entering the range S of the end face 40a of the converging lens array 40 and passing through the converging lens array 40). Therefore, the exposure apparatus 10 can form a clearer image. This is supported by the results of the following experiment.

In this experiment, the diameter of each gradient index lens 41 (d
) Is 0.56 mm, the object side working distance (L ₀ ) is 2.4 mm, and a converging lens array in which α should be 2.5 is employed. The diameter (R) of each light emitting surface 21a was 40 μm, and the diameter (R1) of each opening 31 was 40 μm. Moreover, according to Formula (1), the length (t) of each opening 31 was 0.133 mm. In the exposure apparatus 10 according to this experiment, the outer peripheral surface 110a.
The diameter of the spot image (the image of the light-emitting surface 21a) tied to is about 60 μm. This is much shorter than the diameter (about 70 μm) of the spot image formed by the exposure apparatus in which the opening 30 is removed from the exposure apparatus 10 according to this experiment. That is, the exposure apparatus 10 according to this experiment.
According to this, a clearer image was obtained.

In addition, the converging lens array (the converging lens array in which α should be 2.5) employed in the above experiment is a general one that is widely distributed. Therefore, according to the exposure apparatus 10, the above-described effects can be obtained even when a general converging lens array that is widely distributed is adopted as the converging lens array 40. That is, the exposure apparatus 10 is easy to manufacture.

Further, in the exposure apparatus 10, the opening 30 is formed from a light absorbing member. Therefore, according to the exposure apparatus 10, light reflected by the surface of the opening 30 and light transmitted through the opening 30 can be reduced. Therefore, the light is emitted from the light emitting panel 20 and the opening 3
The possibility that the light incident on the zero surface is used for image formation on the outer peripheral surface 110a can be kept low. That is, the above-described effect can be obtained more reliably.

In the exposure apparatus 10, the dimensions (for example, R1 and t) of each part are determined according to the equation (1), but the specific method for obtaining the dimensions is arbitrary. For example, the dimension may be obtained by calculation using Expression (1), or the dimension may be obtained by trial and error.
The dimension obtained by the latter method satisfies the formula (1) as a result. When the former method is adopted, trial and error for obtaining the dimensions is unnecessary, and thus the design of the exposure apparatus 10 is facilitated. Even when the latter method is used, the exposure apparatus 10 has a condition to be satisfied that the length of each opening 31 is longer than the diameter of the opening 31 on the converging lens array 40 side.
With a small number of trials, a dimension capable of obtaining the above effect can be obtained. Of course, the present embodiment may be modified to eliminate this condition. Further, the present embodiment may be modified so that each opening 31 has a shape other than the rotating body. Further, the present embodiment may be modified to employ an inorganic EL element or an inorganic LED as the light emitting element 21.

Further, the present embodiment may be modified so that a gap between the light emitting panel 20 and the converging lens array 40 is filled with a material having a high light transmittance. The structure of the exposure apparatus according to this embodiment is shown in FIG. In this embodiment, there is a transparent member 50 formed of a material having a high light transmittance such as resin between the light emitting panel 20 and the converging lens array 40. The transparent member 50 is in contact with the light emitting panel 20 and the converging lens array 40 and fills the gap between the opening 30 and the converging lens array 40. Therefore, as shown in the figure, each opening 31 is filled with a material having a high light transmittance.

In this exposure apparatus, there is no solid-gas interface on the optical path of the light emitted from each light emitting element 21 and incident on the converging lens array 40. Therefore, reflection at the interface is suppressed. Further, in this exposure apparatus, the light emitted from each light emitting element 21 does not spread so much because it travels in the solid rather than in the air. That is, the amount of light that is not blocked by the opening 30 increases. Because of these advantages, according to this exposure apparatus, the light utilization efficiency is improved by about 10%. In this exposure apparatus, the gap between each light emitting surface 21a and the gradient index lens 41 is filled with a material having a refractive index higher than that of air. interval is longer than the _{L 0.} That is, the thickness of the light source substrate or the sealing layer and the transparent member is adjusted so that the relationship L ₀ = d1 / n1 + d2 / n2 is established.

Further, by modifying the present embodiment, the opening 30 may be formed from a member that reflects incident light or a member that refracts incident light. Further, only the surface of the opening 30 (including the side surface of the opening 31) may be formed from a material having a high light absorption rate or a material having a high light reflectance. However, in this case, it should be noted that the reflected light or transmitted light from the opening 30 proceeds in a direction in which it does not pass through the gradient index lens 41.

<Image forming apparatus>
FIG. 9 is a longitudinal sectional view of the image forming apparatus according to the embodiment of the present invention. This image forming apparatus is a tandem type full-color image forming apparatus using a belt intermediate transfer body system.

In this image forming apparatus, four optical heads 10K, 10C, 10M, and 10Y having the same configuration are used.
Are four photosensitive drums (image carriers) 110K, 110C, 110M, which have the same configuration.
110Y is disposed at the exposure position. Optical heads 10K, 10C, 10M, 10
Y is an exposure apparatus according to the above-described exposure apparatus 10 or a modification thereof.

As shown in FIG. 9, this image forming apparatus is provided with a driving roller 121 and a driven roller 122, and an endless intermediate transfer belt 120 is wound around these rollers 121 and 122, as indicated by arrows. Thus, the periphery of the rollers 121 and 122 is rotated. Although not shown,
A tension applying unit such as a tension roller that applies tension to the intermediate transfer belt 120 may be provided.

Around the intermediate transfer belt 120, photosensitive drums 110K, 110C, 110M, and 110Y having photosensitive layers on four outer peripheral surfaces are arranged at predetermined intervals. Subscript K
, C, M, and Y mean that they are used to form visible images of black, cyan, magenta, and yellow, respectively. The same applies to other members. Photosensitive drums 110K and 11
0C, 110M, and 110Y are rotationally driven in synchronization with the driving of the intermediate transfer belt 120.

Around each photosensitive drum 110 (K, C, M, Y), a corona charger 111 (K, C,
M, Y), an optical head 10 (K, C, M, Y), and a developing device 114 (K, C, M, Y) are arranged. Corona chargers 111 (K, C, M, Y) have corresponding photosensitive drums 110.
The outer peripheral surface of (K, C, M, Y) is uniformly charged. The optical head 10 (K, C, M, Y)
An electrostatic latent image is written 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 OLED elements 14 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 from the plurality of OLED elements 14. Developer 114 (K
, C, M, and Y) form 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 monochromatic 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 as an object on which an image is finally formed is fed one by one from the sheet feeding cassette 101 by the pickup roller 103, and between the intermediate transfer belt 120 and the secondary transfer roller 126 in contact with the driving roller 121. Sent to the nip. The full-color visible image on the intermediate transfer belt 120 is secondarily transferred to one side of the sheet 102 by the secondary transfer roller 126 and fixed on the sheet 102 by passing through a fixing roller pair 127 as a fixing unit. . Thereafter, the sheet 102 is discharged onto a paper discharge cassette formed on the upper part of the apparatus by a paper discharge roller pair 128.

FIG. 10 is a longitudinal sectional view of another image forming apparatus according to the embodiment of the present invention. This image forming apparatus is a rotary developing type full-color image forming apparatus using a belt intermediate transfer body system. In the image forming apparatus shown in FIG. 10, a corona charger 168, a rotary developing unit 161, an optical head 167, and an intermediate transfer belt 169 are provided around a photosensitive drum (image carrier) 165.

The corona charger 168 uniformly charges the outer peripheral surface of the photosensitive drum 165. Optical head 1
67 writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum 165. Optical head 1
Reference numeral 67 denotes an exposure apparatus according to the exposure apparatus 10 or a modification thereof, and is installed so that the arrangement direction of the plurality of light emitting elements 14 is along the bus line (main scanning direction) of the photosensitive drum 165. The electrostatic latent image is written by irradiating the photosensitive drum with light by the plurality of light emitting elements 14 described above.

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

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

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

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

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

Since each of the image forming apparatuses uses an exposure apparatus that can form a clearer image as the optical head, it is possible to form a high-resolution and high-quality image. As described above, the exposure apparatus 1
Although the image forming apparatus to which the exposure apparatus according to 0 or a modification thereof can be applied has been exemplified, the present invention can also be applied to other electrophotographic image forming apparatuses. Is in range. For example, the present invention can be applied to an image forming apparatus that transfers a visible image directly from a photosensitive drum to a sheet without using an intermediate transfer belt, and an image forming apparatus that forms a monochrome image.

1 is a perspective view showing an outline of an exposure apparatus 10 according to an embodiment of the present invention. 2 is a plan view of a light-emitting panel 20 and an opening 30 constituting the exposure apparatus 10. FIG. 2 is a perspective view showing a configuration of a converging lens array 40 in the exposure apparatus 10. FIG. 2 is a plan view of the exposure apparatus 10. FIG. 1 is a sectional view of an exposure apparatus 10. It is a figure which illustrates the mode of the limitation of the range which light reaches by the opening part. It is a figure for demonstrating Formula (1). 6 is a cross section showing the structure of an exposure apparatus in a form in which a gap between the light emitting panel 20 and the converging lens array 40 is filled with a material having a high light transmittance. 1 is a longitudinal sectional view of an image forming apparatus according to an embodiment of the present invention. It is a longitudinal cross-sectional view of another image forming apparatus according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Exposure apparatus, 20 ... Light emission panel (light emission device), 21 ... Light emitting element, 21a ... Light emission surface,
DESCRIPTION OF SYMBOLS 30 ... Opening part, 31 ... Opening, 40 ... Converging lens array, 41 ... Refractive index distribution type lens, 4
0a ... end face, 50 ... translucent member, 110, 165 ... photosensitive drum (image carrier), 111, 1
68 ... Corona charger (charger), 114, 163Y, 163C, 163M, 163K ... Developer.

Claims (7)

A light emitting device comprising a plurality of light emitting elements arranged along one direction, and emitting light from the plurality of light emitting elements;
An image having a plurality of gradient index lenses capable of forming a real image of erecting equal magnification by transmitting a part of incident light emitted from the light emitting device, and connecting the plurality of gradient index lenses A converging lens array comprising one continuous image;
A plurality of members that are interposed between the light-emitting device and the converging lens array, are formed from members that prevent linear light from traveling straight, and allow a part of the light emitted from the plurality of light-emitting elements to pass through the members. An opening in which an opening is formed;
An exposure apparatus comprising: The length of each of the plurality of openings is longer than the diameter of the opening on the converging lens array side,
The exposure apparatus according to claim 1, wherein: A transparent member that is in contact with the light emitting device and the converging lens array and fills a gap between the light emitting device and the converging lens array;
The exposure apparatus according to claim 1 or 2, wherein Each of the plurality of light emitting elements has a light emitting surface that emits light,
The light incident surface of each of the plurality of gradient index lenses forms part of an end surface of the converging lens array on the light emitting device side,
The opening is plate-shaped,
Each of the plurality of openings has a substantially circular shape on the converging lens array side, and a substantially circular shape from which light from the light emitting element corresponding to the opening reaches an end surface of the converging lens array on the light emitting device side. The scope of
The working distance on the object side of the converging lens array is L ₀ , the diameter on the converging lens array side of each of the plurality of apertures is R1, the diameter or maximum width of the light emitting surface is R, and the plurality of refractive index distributions. When the diameter of each of the mold lenses is d and the ratio of the diameter of the range to the diameter of each of the plurality of gradient index lenses is α, the length t of each of the plurality of apertures is ± 10 %
Expressed by the equation (1) in the error range of
The exposure apparatus according to claim 1, 2, or 3.

The ratio of the diameter of the range to the diameter of each of the plurality of gradient index lenses is 2.25 or more and 2.75 or less.
The exposure apparatus according to claim 4, wherein: The whole or the surface of the member forming the opening is formed from a light-absorbing material,
6. An exposure apparatus according to claim 1, wherein An image carrier;
A charger for charging the image carrier;
The exposure apparatus according to any one of claims 1 to 6, wherein a latent image is formed by irradiating light from the exposure apparatus onto a charged surface of the image carrier.
A developing unit for forming a visible image by attaching toner to the latent image;
An image forming apparatus, wherein the visible image is transferred to another object.

Images