JP3594883B2 - Exposure equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, in electrophotographic image formation, a photoconductor is exposed to image light emitted from a plurality of light emitting elements arranged opposite to an image forming area of the photoconductor, and an electrostatic latent image is formed on the surface of the photoconductor. The present invention relates to an exposure apparatus for forming an image.
[0002]
[Prior art]
In electrophotographic image formation, an electrostatic latent image is formed on the surface of a photoreceptor uniformly charged with a predetermined charge by photoconductive action, and this electrostatic latent image is visualized as a toner image and printed on recording paper. Transcribe. For this reason, an image forming apparatus that performs electrophotographic image formation uses an exposure apparatus that exposes and scans the surface of a photoconductor with image light. As this exposure device, a plurality of light emitting elements are arranged in opposition to the image forming area of the photoconductor, and each light emitting element is driven in accordance with image data, thereby moving in a direction orthogonal to the arrangement direction of the plurality of light emitting elements. There is a type in which an electrostatic latent image is written line by line on the surface of a photoconductor.
[0003]
As described above, an exposure apparatus using a plurality of light emitting elements arranged in a direction orthogonal to the direction of movement of the photoconductor as a light source includes a lens for correcting optical characteristics of image light emitted from each light emitting element. . For example, in the case of using an LED as a light emitting element, a selfoc lens that forms image light on the surface of the photoconductor is arranged in each LED.
[0004]
However, in an exposure apparatus that forms image light using a selfoc lens, the mounting position of the selfoc lens with respect to each LED chip needs to be positioned with high accuracy at the time of assembly work, and there is a problem that the work becomes complicated. Further, when the position between the LED and the selfoc lens varies, there is a problem that the light amount of the image light irradiated on the photoconductor periodically fluctuates and the image forming state is deteriorated.
[0005]
Japanese Patent Application Laid-Open No. 8-156320 discloses that an optical system for guiding a light beam from an LED array to a photoreceptor has a waveguide and a lens or a microlens, and uses an ultraviolet curable resin and an ultraviolet transparent mold. A configuration adapted to be used is disclosed. In this configuration, at a predetermined position on a glass substrate on which an LED array and a driver IC are mounted, a mold having a concave portion corresponding to a waveguide and a lens facing each LED chip constituting the LED array is placed. By irradiating ultraviolet rays after filling the concave portions of the mold with the ultraviolet curable resin, the waveguide and the lens facing each LED chip can be easily formed at appropriate positions.
[0006]
Japanese Patent Application Laid-Open No. Hei 6-24042 discloses a correction method for forming a plurality of liquid crystal microlenses in an array corresponding to each LED chip constituting an LED array and correcting a variation in light emission intensity of each LED chip. A configuration is disclosed in which a voltage applied to each liquid crystal microlens is controlled based on data. In this configuration, the light amount on the surface of the photoreceptor is made uniform by changing the focal length by changing the distribution of the refractive index in the liquid crystal microlenses according to the variation in the emission intensity of each LED chip constituting the LED array, To prevent the density unevenness and the gradation reproducibility from being deteriorated.
[0007]
[Problems to be solved by the invention]
However, in a conventional exposure apparatus including the configurations disclosed in JP-A-8-156320 and JP-A-6-24042, the image light emitted from the light emitting elements is arranged at intervals between the light emitting elements on the surface of the photoconductor. Since the optical system for distributing light in a narrower range is disposed between the light emitting element and the photoconductor, the diameter of the exposure spot on the surface of the photoconductor is reduced, and the distance between adjacent exposure spots is increased. For this reason, in the reversal development method in which a portion of the surface of the photoreceptor that is not exposed to image light at all is exposed between the exposure spots and toner adheres to the portion of the surface of the photoreceptor exposed by the exposure device, White spots will be formed between spots.
[0008]
It is an object of the present invention to enlarge image light emitted from each light emitting element on the image space side of a microlens disposed between the light emitting element and the photosensitive member, thereby irradiating the image light from the light emitting element with an increase in resolution of an image. Provided is an exposure apparatus capable of reliably preventing the occurrence of white spots in an image by making adjacent exposure spots partially overlap on a photoreceptor even when a light beam of image light is reduced in size. It is in.
[0009]
[Means for Solving the Problems]
The present invention has the following arrangement as means for solving the above-mentioned problems.
[0010]
(1) In an exposure apparatus that irradiates image light from a plurality of light emitting elements arranged at a predetermined arrangement interval facing an image forming range of a photoconductor,
On a substrate, a plurality of light emitting elements arranged in one direction across the insulating material, the transparent electrode layer located on an upper surface of the plurality of light emitting elements, to cover the entire upper surface of the insulating material and the transparent electrode layer insulation layer, wherein the top surface flat optical path length regulation layer that covers the entire upper surface of the insulating layer, a light shielding material disposed in an intermediate position of the light emitting element and the transparent electrode layer adjacent the upper surface of the optical path length regulation layer comprising electrodes, a liquid crystal resin, which is disposed between the upper surface and the transparent electrode of the optical path length regulation layer comprising electrodes made of the light-shielding material, wherein the transparent electrode covering the entire upper surface of the liquid crystal resin, and said transparent A protective layer covering the entire surface of the electrode is formed in this order.
[0011]
(2) The layer thickness of the optical path length adjustment layer is larger than the layer thickness of the transparent electrode layer, at least the irradiation angle of image light from the light emitting element, the refraction angle of the liquid crystal resin, the photosensitive drum from the upper surface of the liquid crystal resin. The distance is determined in consideration of the distance to the peripheral surface and the exposure spot diameter on the peripheral surface of the photosensitive drum.
In this configuration, the image light emitted from each of the plurality of light emitting elements arranged to face the image forming area of the photoconductor is expanded on the image space side of the microlens and distributed to the photoconductor. Therefore, even when the light beam diameter of the light emitting element is reduced due to the increase in the resolution of the image, the diameter of the adjacent exposure spot on the surface of the photoconductor becomes large, and the image does not have white spots.
[0012]
In the above configuration, preferably, the light emitting element should be an EL element.
[0013]
According to this configuration, it is possible to easily form a long light emitting body facing the image forming area of the photoconductor by the plurality of EL elements.
[0015]
In this configuration, the optical path length adjustment layer and the microlens of the magnifying optical system are arranged in this order on the photoconductor side of the light emitting element. Therefore, the microlens of the magnifying optical system is formed on the photoconductor side of the light emitting element with the optical path length adjusting layer interposed therebetween, and the unevenness on the side where the microlens is arranged in the light emitting element is removed, and the thickness of the optical path length adjusting layer is reduced. Is set to an appropriate value, the microlens is arranged at a predetermined optical position with respect to the light emitting element.
[0017]
In this configuration, a liquid crystal lens for expanding a light beam is disposed on the photoconductor side of the light emitting element. Therefore, by adjusting the voltage applied to the liquid crystal lens, the diameter of the light beam emitted from the light emitting element can be easily expanded to a predetermined size.
[0019]
In this configuration, a microlens of a magnifying optical system made of a liquid crystal resin that is polymerized by application of an electric field is disposed on the photoconductor side of the light emitting element. Therefore, once a predetermined electric field is applied to polymerize the liquid crystal resin, the optical characteristics of the microlens are fixedly maintained, and there is no need to repeatedly apply the electric field.
[0021]
In this configuration, the electrodes for applying an electric field to the liquid crystal resin forming the microlenses are formed using a light-shielding material. Therefore, the electrode that applies an electric field for polymerizing the liquid crystal resin functions as a member that blocks stray light between the light emitting elements.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic diagram showing a configuration of a main part of an image forming apparatus including an exposure apparatus according to an embodiment of the present invention. This image forming apparatus rotatably supports a photosensitive drum 11 having a photosensitive layer having a photoconductive function formed on the surface of a cylindrical substrate made of aluminum or the like, and a charging roller 12 around the photosensitive drum 11. The exposing device 1, the developing unit 13, the transfer roller 14, and the cleaner 15 are arranged in this order, and further, a fixing roller 16 is provided downstream of the transfer roller in the sheet conveying direction.
[0023]
The photoreceptor drum 11 rotates in the direction of the arrow by receiving a supply of rotational force from a drive motor (not shown) via a gear. The charging roller 12 uniformly applies a charge of a single polarity to the surface of the photoconductor drum 11. The exposure device 1 irradiates the surface of the photosensitive drum 11 with image light modulated by image data. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 11 by photoconductive action. The developing unit 13 supplies toner to the surface of the photoconductor drum 11 to visualize the electrostatic latent image into a toner image. The transfer roller 14 transfers the toner image from the surface of the photosensitive drum 11 to the surface of the sheet S by electrostatic force. The cleaner 15 removes the toner remaining on the surface of the photosensitive drum 11 after the transfer process. The fixing roller 16 heats and pressurizes the sheet S on which the toner image has been transferred, melts the toner image, and firmly fixes the sheet S on the surface of the sheet S.
[0024]
FIG. 2 is a plan view and a sectional view showing the configuration of the exposure apparatus according to the first embodiment of the present invention. FIG. 2B is a sectional view taken along the line AA ′ in FIG. 2A. The exposure apparatus 1 according to this embodiment uses an LED element 21 as a light emitting element. That is, the exposure apparatus 1 forms an LED array 22 in which a plurality of LED elements 21 are arranged at a fixed arrangement interval P over substantially the entire area of the peripheral surface of the photosensitive drum 11 in the rotation axis direction (main scanning direction). It is provided as a light source. On the entire upper surface of the LED array 22, an optical path length adjusting layer 23 made of a transparent resin and having a predetermined thickness is formed. Further, a micro lens 25 is fixed at a position facing each LED element 21 on the upper surface of the optical path length adjusting layer 23.
[0025]
The optical path length adjusting layer 23 smoothes the upper surface of the LED array 22 from which the transparent electrode 24 for supplying power to each LED element 21 protrudes, and makes the optical path length between each LED element 21 and the microlens 25 appropriate. Therefore, the layer thickness of the optical path length adjusting layer 23 depends on the irradiation angle of the image light from the LED element 21, the refractive index of the microlens 25, the distance between the microlens 25 and the peripheral surface of the photosensitive drum 11, and the photosensitive drum. 11 is determined on the basis of the required exposure spot diameter and the like on the peripheral surface.
[0026]
The micro lens 25 enlarges the image light emitted from the LED element 21 on the image space side and distributes the light on the peripheral surface of the photosensitive drum 11. Therefore, the exposure spot diameter on the peripheral surface of the photosensitive drum 11 is wider than the arrangement interval P of the LED elements 21. That is, the microlenses 25 emit the image light emitted from each LED element 21 in a state where the exposure spots of the image light emitted from the adjacent LED elements 21 on the peripheral surface of the photosensitive drum 11 partially overlap each other. Light is distributed on the peripheral surface of the photosensitive drum 11. As a result, the image forming range on the peripheral surface of the photosensitive drum 11 is exposed by the image light over the entire area in the main scanning direction, and there is no occurrence of white spots where images are partially missing.
[0027]
FIG. 3 is a view showing a manufacturing process of the exposure apparatus according to the second embodiment of the present invention. The exposure apparatus 30 according to this embodiment uses an EL element as a light emitting element, and uses a liquid crystal resin lens as a micro lens of the magnifying optical system. In manufacturing the exposure apparatus 30, first, an EL material layer 32 and a transparent electrode layer 33 are formed in this order on the entire upper surface of an aluminum substrate 31, and then a plurality of positions are formed on the upper surface of the transparent electrode layer 33 at predetermined intervals. Then, a photoresist 34 is arranged and formed (FIG. 3A). The arrangement direction of the photoresist 34 is the main scanning direction which is the rotation axis direction of the photosensitive drum 11.
[0028]
Next, after removing the EL material 32 and the transparent electrode layer 33 from the portion of the upper surface of the aluminum substrate 31 where the photoresist 34 is not formed (FIG. 2B), the entire surface of the upper surface of the aluminum substrate 31 is made of an insulating material 35. (FIG. (C)), and the photoresist 34 and the insulating material 35 are removed from the upper surface of the transparent electrode layer 33 (FIG. (D)).
[0029]
Then, after covering the entire surface of the insulating material 35 on the upper surface of the aluminum substrate 31 and the upper surface of the transparent electrode layer 33 with the insulating film 36 (FIG. 9E), the optical path length is formed on the upper surface of the insulating film 36 using a transparent resin as a material. An adjustment layer 37 is formed (FIG. (F)), and an electrode 38 is formed at an intermediate position between the adjacent EL material 32 and the transparent electrode layer 33 on the upper surface of the optical path length adjustment layer 37 by vapor deposition of aluminum or the like (FIG. G)).
[0030]
Furthermore, after placing the liquid crystal resins 4 0 between the upper surface and the transparent electrode 39 of the optical path length adjusting layer 37 to form a protective layer 41 on the upper surface of the transparent electrode 39 (FIG. (H)), an electrode 38 By applying a predetermined voltage to the transparent electrode 39, the liquid crystal resin 40 is polymerized so as to have a predetermined refraction angle, and the exposure device 30 is completed.
[0031]
In this configuration, the optical path length adjustment layer 37 smoothes the uneven surface on the upper surface of the aluminum substrate 31 on which the microlenses of the magnifying optical system constituted by the liquid crystal resin 40 are to be formed, and also includes the EL material 32 and the transparent electrode layer 33. It is formed to adjust the optical path length from the EL element constituted by the liquid crystal resin 40 to the liquid crystal resin 40. Therefore, the layer thickness of the optical path length adjustment layer 37 is larger than the layer thickness of the transparent electrode layer 33, and the irradiation angle of image light from the EL element, the refraction angle of the liquid crystal resin 40, and the And the exposure spot diameter on the peripheral surface of the photosensitive drum 11.
[0032]
As described above, by applying a predetermined voltage between the electrode 38 and the transparent electrode 39, the liquid crystal resin 40 is polymerized in a molecular arrangement having a predetermined refraction angle, and converts the image light irradiated from the EL element. The image is enlarged on the image space side and is irradiated on the peripheral surface of the photosensitive drum 11. As a result, the image light emitted from the adjacent EL element is distributed on the peripheral surface of the photosensitive drum 11 in a state where the exposure spot on the peripheral surface of the photosensitive drum 11 partially overlaps with each other. The image forming range on the peripheral surface is exposed by the image light over the entire area in the main scanning direction, and there is no occurrence of white spots where images are partially missing.
[0033]
Further, in the exposure device 30, since the EL element is used as the light emitting element, the light emitting element is extended over a relatively wide area facing the entire image forming area in the main scanning direction on the peripheral surface of the photosensitive drum 11. Exposure light sources arranged in a scale can be formed relatively easily.
[0034]
As the polymerizable liquid crystal resin material constituting the liquid crystal resin 40, for example, those disclosed in JP-A-5-72403 or JP-A-9-5695 can be used. After the liquid crystal resin 40 is once polymerized and cured by applying a predetermined voltage between the electrode 38 and the transparent electrode 39, it is not necessary to apply a voltage to the electrode 38 again. However, since the electrode 38 is located between the EL elements above the EL element, crosstalk due to stray light of image light between the EL elements is prevented by configuring the electrode 38 with a light-shielding material. And the image forming state can be favorably maintained.
[0035]
Further, the light emitting element in the exposure apparatus of the present invention is not limited to the LED element or the EL element. Furthermore, the microlens of the magnifying optical system in the exposure apparatus of the present invention is not limited to a resin lens or a liquid crystal resin lens. For example, a liquid crystal lens whose refractive index changes according to a voltage applied to an electrode may be used. it can.
[0036]
【The invention's effect】
The present invention has the following effects.
[0037]
(1) The image light emitted from each of the plurality of light emitting elements arranged opposite to the image forming area of the photoconductor is enlarged on the image space side of the microlens and distributed to the photoconductor, thereby forming an image. Even when the light beam diameter of the light emitting element is reduced due to the increase in resolution, the diameter of the adjacent exposure spot on the surface of the photoreceptor can be increased, thereby preventing the occurrence of white spots in the image and forming an image. A good state can be maintained.
[0038]
(2) By arranging the optical path length adjustment layer and the microlens of the magnifying optical system on the photoconductor side of the light emitting element in this order, the microlens of the magnifying optical system is formed on the photoconductor side of the light emitting element with the optical path length adjustment layer interposed therebetween. In addition, it is possible to remove irregularities on the side where the microlens is arranged in the light emitting element, and to arrange the microlens at a predetermined optical position with respect to the light emitting element by setting the thickness of the optical path length adjusting layer to an appropriate value. Can be.
[0039]
(3) By arranging a liquid crystal lens for expanding the light beam on the photoconductor side of the light emitting element, the voltage applied to the liquid crystal lens can be adjusted to easily adjust the diameter of the light beam emitted from the light emitting element to a predetermined size. Can be expanded.
[0040]
(4) By disposing a microlens of an enlarging optical system made of a liquid crystal resin which is polymerized by applying an electric field to the photoreceptor side of the light emitting element, once a predetermined electric field is applied to polymerize the liquid crystal resin, The optical properties of the lens are kept fixed and there is no need to repeatedly apply an electric field.
[0041]
(5) By forming an electrode for applying an electric field to the liquid crystal resin constituting the microlens using a light-shielding material as a material, this electrode can function as a member for blocking stray light between the light emitting elements, thereby forming an image. Deterioration of the state can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of a main part of an image forming apparatus including an exposure apparatus according to an embodiment of the present invention.
FIG. 2 is a plan view and a cross-sectional view illustrating a configuration of an exposure apparatus according to a first embodiment of the present invention.
FIG. 3 is a view showing a manufacturing process of an exposure apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
1, 30-exposure device 11-photoconductor drum 21-LED element (light emitting element)
23, 37-optical path length adjustment layer 25-resin lens (micro lens)
32-EL material 40-Liquid crystal resin

Claims (1)

In an exposure apparatus that irradiates image light from a plurality of light emitting elements arranged at a predetermined arrangement interval facing the image forming range of the photoconductor,
On a substrate, a plurality of light emitting elements arranged in one direction across the insulating material, the transparent electrode layer located on an upper surface of the plurality of light emitting elements, to cover the entire upper surface of the insulating material and the transparent electrode layer insulation layer, wherein the top surface flat optical path length regulation layer that covers the entire upper surface of the insulating layer, a light shielding material disposed in an intermediate position of the light emitting element and the transparent electrode layer adjacent the upper surface of the optical path length regulation layer comprising electrodes, a liquid crystal resin, which is disposed between the upper surface and the transparent electrode of the optical path length regulation layer comprising electrodes made of the light-shielding material, wherein the transparent electrode covering the entire upper surface of the liquid crystal resin, and said transparent An exposure apparatus, wherein a protective layer covering the entire surface of the electrode is formed in this order.

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