JP2006091332A - Optical destaticization device and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformize light quantity distribution of emitted light to be emitted on a photoreceptor to remove charge of the photoreceptor in an electrophotographic image forming apparatus. <P>SOLUTION: Light quantity distribution of the emitted light to be emitted on the photoreceptor drum 1 is uniformized by forming a diffuse-reflecting face 12c which reflects light from an LED lamp 11 toward the photoreceptor drum 1 in a light transmission body 12 and performing light quantity correction by varying height H to an light emission surface 12b of the diffuse-reflecting face 12c and width W of the diffuse-reflecting face 12c according to distance from the LED lamp 11. In addition, since light leaked from the diffuse-reflecting face 12c is reflected by a reflective film 13 stuck on the upper surface near the rear end part of the light transmission body 12 and returned to the inside of the light transmission body 12, light quantity of the emitted light from the light emission surface 12b near the rear end part of the light transmission body 12 increases and the light quantity distribution of the emitted light is further uniformized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photostatic discharger that removes residual charges on a photoreceptor by light irradiation in an electrophotographic image forming process, and an image forming apparatus such as a copying machine including the same.

  An electrophotographic image forming apparatus is an apparatus that forms an image by each process of charging, exposure, development, transfer, and fixing. For example, in the case of a copying machine, the above processes are performed as follows.

  First, an electrostatic latent image is formed by exposing reflected light of an original image through an optical system on the surface of a photoconductor (photosensitive drum) given a uniform charge by a charger charger. A toner (developer) is electrostatically attached to the image and developed to form a toner image on the photoreceptor. Next, the toner image is transferred onto the recording paper by applying static electricity having a polarity opposite to that of the toner image to the transfer body, and the transferred toner is fixed by heating and pressurizing, and an image corresponding to the original image is formed on the recording paper. Immobilize.

  Many functional elements are added to the basic configuration of the copying machine configured as described above for the purpose of improving the image quality and the efficiency of forming a copied image. For example, this corresponds to an optical static elimination device that neutralizes the charge on the photosensitive member by light irradiation. Examples of the light neutralizing device include an eraser that erases a defective latent image in a non-image area on a photoconductor before development processing, a pre-transfer neutralization lamp (PTL) that optically lowers the potential on the photoconductor before transfer processing, Examples thereof include a static elimination lamp (QL) that removes residual charges on the photoconductor after the cleaning process.

  A discharge tube such as a fluorescent tube is used as an illumination light source of such a light neutralizing device. Further, as shown in FIG. 19, an LED array 500 in which a large number of LED chips 502 are arranged on a substrate 501 is used. In particular, in recent years, there has been a demand for products that are smaller and less expensive.

  As shown in FIG. 20, the LED array 500 has a high illuminance substantially uniform with respect to the surface of the photosensitive drum 1 that is an illuminated surface by closely arranging LED chips (LED lamps) 502. Can be obtained.

  However, in this configuration, since the number of LED chips 502 used is large, it is difficult to achieve a sufficient cost reduction in terms of cost. Further, when the number of LED chips 502 used is reduced in order to achieve cost reduction, the spacing between the LED chips 502 increases, and the illuminance distribution of the photosensitive drum 1 is uneven, thereby obtaining uniform illuminance. I can't.

  As a technique for solving such a problem, a columnar member made of a translucent material, a light irradiation surface provided on a side surface portion along the longitudinal direction, and a cutting process or roughening provided on a surface opposite to the light irradiation surface. There has been disclosed an illumination device that includes a light guide having a light diffusing portion by surface processing and that has a light source provided at an end of the light guide (see, for example, Patent Document 1).

Further, there is disclosed an optical static eliminator including a point light source that is detachably attached to the image forming apparatus main body and a light guide that constitutes an optical path that guides incident light from the point light source to the photosensitive member (for example, , See Patent Document 2.)
JP 08-043333 A JP 2002-278395 A

  However, according to the configuration described in each of the above-mentioned patent documents, among the areas where light is irradiated from the light guide to the photosensitive drum, the irradiation light amount is large in the area close to the light source, and the irradiation is performed in the area far from the light source. The problem of low light intensity remains. If the distribution of the irradiation light amount varies in the longitudinal direction of such a photosensitive drum, image unevenness or the like occurs and a good image cannot be obtained. In particular, in the vicinity of the terminal portion of the light guide that is farthest from the light source, the degree of decrease in the amount of irradiation light is large, and improvement of this point is required.

  The present invention has been made in view of such circumstances, and in an electrophotographic image forming apparatus, the light amount distribution of irradiation light irradiated on a photoconductor to remove the charge on the photoconductor is made more uniform. It is an object of the present invention to provide an optical static elimination device capable of performing the above-mentioned and an image forming apparatus including the optical static elimination device having such characteristics.

  An optical static elimination device of the present invention is an optical static elimination device used to neutralize charges on a photoconductor in an electrophotographic image forming apparatus, a light guide disposed opposite to the photoconductor, A light source that irradiates light onto the light incident surface of the light guide, and the light guide is formed with a diffuse reflection surface that reflects light from the light source toward the photoconductor, The height of the light guide relative to the light exit surface to the photoconductor and the width of the diffuse reflection surface (the length in the direction orthogonal to the longitudinal direction of the photoconductor) change according to the distance from the light source. And the reflection member is arrange | positioned in the terminal part vicinity upper surface of the said light guide.

  The photostatic discharge device of the present invention is a photostatic discharge device used to discharge charges on a photoconductor in an electrophotographic image forming apparatus, and a light guide disposed opposite to the photoconductor. A light source that irradiates light onto the light incident surface of the light guide, and the light guide is formed with a diffuse reflection surface that reflects the light from the light source toward the photoconductor, and the diffuse reflection The surface has a height relative to the light emitting surface of the light guide to the photoconductor, and the width of the diffuse reflection surface changes according to the distance from the light source, and is on the upper surface in the vicinity of the end portion of the light guide. A groove is formed across the light guide.

  A reflective member is disposed on the upper surface in the vicinity of the terminal end of the light guide and on the inner surface of the groove that crosses the light guide.

  Furthermore, the photostatic discharge device of the present invention is a photostatic discharge device used for discharging charges on a photoconductor in an electrophotographic image forming apparatus, comprising a light guide disposed opposite to the photoconductor. A light source that irradiates light onto the light incident surface of the light guide, and the light guide is formed with a diffuse reflection surface that reflects the light from the light source toward the photoconductor, and the diffuse reflection The surface has a height with respect to the light emitting surface of the light guide to the photoconductor and the width of the diffuse reflection surface changes according to the distance from the light source, and the end of the light guide is steep. It has an inclined surface.

  A reflecting member is disposed on the upper surface near the terminal end of the light guide and the steeply inclined surface.

  In addition, the light guide is folded back, and a reflection surface for folding the optical path of the light guide is provided at the folded portion of the light guide.

  On the other hand, the image forming apparatus of the present invention is an image forming apparatus in which the image forming units including the respective photoconductors are arranged in tandem, and each of the photoconductors is provided with the photostatic discharge device of the present invention.

  According to the light neutralizing device of the present invention, the light guide having the diffuse reflection surface that reflects the light from the light source toward the photoconductor, and the light to the photoconductor of the diffuse reflection surface of the light guide is provided. Since the height with respect to the emission surface and the width of the diffuse reflection surface are changed according to the distance from the light source, the light quantity distribution of the irradiation light irradiated on the photoconductor can be made more uniform.

  And since the reflection member is arrange | positioned in the upper surface vicinity of the termination part of a light guide, the light quantity of the irradiation light irradiated to a photoconductor from the termination part vicinity of a light guide is increased by reflection of the light by this reflection member. And the light quantity distribution of the irradiation light can be made more uniform.

  Alternatively, even when a groove is formed across the light guide on the upper surface in the vicinity of the terminal end of the light guide, the photosensitive member is irradiated from the vicinity of the terminal end of the light guide by reflection of light on the inner surface of the groove. The amount of irradiation light can be increased, and the distribution of the amount of irradiation light can be made more uniform.

  Furthermore, if the reflecting member is disposed on the upper surface in the vicinity of the terminal end of the light guide and the inner surface of the groove crossing the light guide, the amount of irradiation light from the vicinity of the terminal end of the light guide can be further increased. The uniformity of the light amount distribution of the irradiation light is further improved.

  In addition, even when the end portion of the light guide has a steep inclined surface, the amount of irradiation light irradiated to the photosensitive member from the vicinity of the end portion of the light guide is increased by reflection of light on the steep inclined surface. And the light quantity distribution of the irradiation light can be made more uniform.

  Furthermore, if the reflecting member is arranged on the upper surface near the terminal end of the light guide and a steeply inclined surface, the amount of irradiation light from the vicinity of the terminal end of the light guide can be further increased, and the light amount distribution of the irradiation light Is more improved.

  In addition, since the light guide is folded and a reflection surface for folding the optical path of the light guide is provided at the folded portion of the light guide, the length of the light guide in the optical axis direction is not increased. The optical path length of the charge removal region can be increased. As a result, it is possible to reduce the size of the image forming apparatus.

  On the other hand, in the image forming apparatus of the present invention, the light neutralizing device having the above-described features is attached to the photoreceptor of each image forming unit arranged in tandem. In order to reduce the size of such an image forming apparatus, it is necessary to reduce the size of each image forming unit. Therefore, it is preferable to use a small-sized light neutralizing device for each image forming unit. Since the light neutralizing device having the above-described features is a simple configuration including a light guide disposed opposite to the photoconductor and a light source that irradiates light to the light incident surface of the light guide, the size of the light static elimination device can be reduced. be able to. Therefore, each image forming unit can also be reduced in size, which is effective in realizing downsizing of the image forming apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
-Image forming device-
FIG. 1 is a diagram illustrating an example of an image forming apparatus according to the present invention.

  The image forming apparatus 100 in this example is a digital multi-function peripheral capable of facsimile operation, copy operation, and printer operation, and includes an image reading unit 101, an image forming unit 102, a paper feeding unit 103, and a post-processing device 104. ing.

  An image reading unit 101 is provided as an image input device of the image forming apparatus 100 for reading an image such as a document. (Referred to as RADF) 106 and an optical system unit 110.

  The image reading unit 101 sequentially reads images of the original document one by one from the original document placed on the document placement table 105. The RADF 106 conveys originals set on a predetermined original tray one by one to the original placing table 105, and after the image is read by the optical system unit 110, it is carried out to a predetermined extraction position.

  The optical system unit 110 is configured as a document image reading unit that reads an image of a document conveyed to the document placing table 105 in predetermined units in the scanning line direction. The optical system unit 110 includes a first mirror base 111, a second mirror base 112, an optical lens 117, and a photoelectric conversion element (hereinafter referred to as a CCD) 118.

  The first mirror base 111 includes a lamp reflector assembly 113 for irradiating light, and a first reflection mirror 114 for guiding reflected light from the document to a second mirror base 112 described later, and a document placement table. The original is irradiated with light while moving at a constant speed V from left to right in FIG.

  The second mirror base 112 includes a second reflection mirror 115 and a third reflection mirror 116 that guide light from the first mirror base 111 in the direction of the optical lens 117 and the CCD 118. Following the operation of the base 111, it moves at a speed of V / 2.

  The optical lens 117 focuses the reflected light from the second mirror base 112 on the CCD 118. The CCD 118 converts the light imaged by the optical lens 117 into an electrical signal. The analog electrical signal obtained by the CCD 118 is converted into image data of a digital signal, subjected to various image processing, and then transferred to the image forming unit 102 through a buffer memory or the like as appropriate.

  The image forming unit 102 includes an image forming unit 120 and an exposure unit 121. The exposure unit 121 exposes the photosensitive drum 1 in accordance with image data read from the buffer memory or image data transferred from an external device. Although not shown, the exposure unit 121 is a semiconductor laser light source that irradiates laser light, a polygon mirror that polarizes the laser light at an equiangular velocity, and further polarizes light from the polygon mirror so as to be constant speed on the photosensitive drum 1. An f-θ lens to be moved is provided.

  As shown in FIG. 2, the image forming unit 120 includes a photosensitive drum 1 that carries an electrostatic latent image. In the periphery of the photosensitive drum 1, toner is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 1 by the charging device 2 that charges the surface of the photosensitive drum 1 to a predetermined potential and the exposure unit 121. The developing device 3 for visualizing, the transfer device 4 for transferring the toner image on the surface of the photosensitive drum 1 to a sheet, the cleaning device 5 for cleaning the surface of the photosensitive drum 1, and the residual charge on the photosensitive drum 1 are neutralized. The light neutralizing device 10 is arranged in this order, and charging, exposure, development, transfer, cleaning, and neutralization processes are performed on the surface of the photosensitive drum 1. Note that a sheet on which a predetermined image forming process has been performed in the image forming unit 120 is heated and fixed by a fixing device 107 provided downstream of the image forming unit 120, and is discharged from the paper discharge roller 137. Paper.

  On the downstream side of the image forming unit 120 and the fixing device 107, a switchback conveyance path 136 that reverses the sheet for forming images on both sides of the sheet and an elevating tray 141 are provided, and the sheet on which the image is fixed is provided. A post-processing device 104 that performs stapling processing or the like is disposed.

  The paper feed unit 103 is disposed below the image forming unit 120, and includes a multi-stage paper feed unit including a manual feed tray 134, a duplex unit 135, paper cassettes 131, 132, and 133, and a storage unit for these sheets ( 131 to 134) are provided with conveying means for conveying the sheet to the image forming unit 120. Note that the duplex unit 135 communicates with the switchback conveyance path 136 and is used when image formation is performed on both sides of the sheet.

-Optical neutralization device-
Next, the optical static elimination device 10 will be described.

  As shown in FIGS. 3 to 5, the light neutralizing device 10 includes an LED lamp 11 that is a point light source and a light guide (made of a light-transmitting material) 12.

  The light guide 12 is mounted on the process cartridge 20 as shown in FIGS. The process cartridge 20 is detachable by sliding on a cartridge guide member 23 attached to the front frame 21 and the rear frame 22 of the main body of the image forming apparatus 100.

  The LED lamp 11 is disposed to face the end portion 20a on the front end side in the mounting direction indicated by the arrow M of the process cartridge 20 that is a non-image forming area of the photosensitive drum 1.

  As shown in FIGS. 3 and 4, the light guide 12 is a band-shaped member extending in a direction parallel to the photosensitive drum 1, and a surface facing the photosensitive drum 1 is a light emitting surface 12 b. One end surface (tip surface) in the longitudinal direction of the light guide body 12 is a light incident surface 12a, and the LED lamp 11 faces the light incident surface 12a.

  The light guide body 12 is formed with a light guide path portion X1 that becomes a light guide path of light from the LED lamp 11, and a reflection portion X2 and a reflection portion X3 that constitute a charge removal region.

  The reflection part X2 is processed so that the light emission surface 12b and the back surface 12d thereof are parallel to each other. The reflecting portion X3 is processed so that the back surface 12d is inclined with respect to the light emitting surface 12b, and the back surface 12d approaches the light emitting surface 12b toward the rear end surface 12e of the light guide 12.

  The back surface 12d of the light guide 12 is formed with a diffuse reflection surface (prism surface) 12c that reflects light from the LED lamp 11 toward the photosensitive drum 1 in a region corresponding to the reflection portion X2 and the reflection portion X3. Has been. The height H of the diffuse reflection surface 12c with respect to the light emission surface 12b is constant in the reflection portion X2. In addition, the height H of the diffuse reflection surface 12c in the reflection portion X3 with respect to the light emission surface 12b decreases toward the rear end portion of the reflection portion X3 (the rear end surface 12e of the light guide 12). Further, the width W of the diffuse reflection surface 12c (the length in the direction orthogonal to the axial direction of the photosensitive drum 1) is not constant, and as shown in FIG. 4B, the end of the reflection portion X2 on the light incident side. From the middle of the reflecting portion X2, the width decreases toward the reflecting portion X3, and the width increases toward the rear end portion of the reflecting portion X3 (the rear end surface 12e of the light guide 12).

  Further, in the vicinity of the rear end portion of the light guide 12, a reflection film 13 with aluminum vapor deposition or the like is attached to the diffuse reflection surface 12 c. In the diffuse reflection surface 12c, light is almost reflected by the prism surface, but a small amount of light is transmitted and leaks outside. The reflection film 13 reflects the light leaking from the diffuse reflection surface 12c and returns the reflected light to the inside of the light guide 12 through the diffuse reflection surface 12c.

  As described above, the light guide 12 in this example has the height H (the length in the Y direction) with respect to the light exit surface 12b of the diffuse reflection surface 12c that reflects the light from the LED lamp 11 toward the photosensitive drum 1. However, the width W of the diffuse reflection surface 12c also changes corresponding to the position relative to the LED lamp 11 (position in the X direction). Therefore, the light intensity distribution of the irradiation light to the photosensitive drum 1 can be made uniform over the entire area in the axial direction (longitudinal direction) of the photosensitive drum 1.

  Further, in the vicinity of the rear end portion of the light guide 12, a reflection film 13 is attached to the diffuse reflection surface 12 c, and the light leaking from the diffuse reflection surface 12 c is reflected by this reflection film 13 and returned to the inside of the light guide 12. Therefore, the amount of light irradiated from the light exit surface 12b in the vicinity of the rear end portion of the light guide 12 is increased, and the light amount distribution of the irradiated light can be further uniformized.

  As a result, a high-quality image with no image unevenness can be obtained.

  Here, the light guide 12 used in the light neutralization device 10 of this example is a surface having a smooth entire surface other than the diffuse reflection surface 12c on which irregularities such as a prism surface are formed. The light guide 12 is formed by molding a transparent material such as an acrylic resin, a polycarbonate resin, a polystyrene resin, a vinyl chloride resin, or glass by an injection molding method or an extrusion method, and performing a treatment such as polishing as necessary. Alternatively, the entire surface of the light guide 12 is a smooth surface, and a cloudy diffusion tape is attached only to the portion that is the diffuse reflection surface 12c, and the reflection film 13 is further diffused near the rear end of the light guide 12. It is also possible to manufacture by overlapping and pasting.

  The LED lamp 11 used in the light neutralizing device 10 of this example is manufactured by bonding an LED chip on a metal lead and sealing the portion in a lens shape with a transparent resin. Near the light incident surface 12a. Examples of the LED lamp 11 include an ultra-bright LED lamp (Sharp, product number: GL5ZJ43) having a wavelength of 618 nm and an experimental resistance value of 200Ω.

  Note that, here, an image forming apparatus that forms a monochrome image by one image forming unit 102 is illustrated, but the above-described light neutralizing apparatus 10 can also be applied to a color image forming apparatus. In a color image forming apparatus, each image forming unit is arranged in tandem for each color such as black, magenta, cyan, yellow, etc., and each color forming unit directly forms an image of each color on a recording sheet. Alternatively, each color image is formed by being superimposed on a recording sheet via an intermediate transfer belt. In order to reduce the size of such a color image forming apparatus, it is necessary to reduce the size of each image forming unit. Therefore, it is preferable to apply a small-sized photostatic device for each image forming unit. Since the above-described light neutralizing device 10 has a simple configuration including the light guide 12 disposed to face the photosensitive drum 1 and the LED lamp 11 that irradiates light to the light incident surface of the light guide 12, Miniaturization can be achieved. Therefore, each image forming unit can also be reduced in size, which is effective in realizing a reduction in size of the color image forming apparatus.

<Embodiment 2>
Another example of the optical static eliminating device of the present invention is shown in FIGS.

  The light neutralizing device 210 of this example includes 212 arranged to face the photosensitive drum 1 (see FIG. 3), and the LED lamp 11 that irradiates light to the light incident surface 212a of the light guide 212. Yes.

  Most of the back surface 212d of the light guide 212 is an inclined surface, and a diffuse reflection surface (prism surface) 212c for reflecting light from the LED lamp 11 toward the photosensitive drum 1 is formed on the inclined surface. Yes.

  The diffuse reflection surface 212c of the light guide 212 has a height H with respect to the light emission surface 212b and a width W of the diffusion reflection surface 212c (the length in a direction orthogonal to the axial direction of the photosensitive drum 1) as an LED light source. 11 is formed so as to become smaller at a constant ratio toward the rear end face 212e of the light guide 212 in accordance with the distance from the light guide 212.

  Further, as shown in an enlarged view in FIG. 7, a V-shaped groove 212f is formed across the light guide 212 in the vicinity of the rear end of the light guide 212, and a diffuse reflection surface is formed in the vicinity of the rear end of the light guide 212. A reflective film 213 with aluminum vapor deposition or the like is attached to the surfaces 212g and 212h of 212c and the V-shaped groove 212f. In the diffuse reflection surface 212c, light is almost reflected by the prism surface, but a small amount of light is transmitted and leaks outside. The reflection film 213 on the diffuse reflection surface 212c reflects the light leaking from the diffuse reflection surface 212c and returns the reflected light to the inside of the light guide 212 through the diffuse reflection surface 212c. In addition, at the rear end portion of the light guide 212, most of the light tends to leak from the rear end surface 212e. The reflection film 213 on the one surface 212g of the V-shaped groove 212f reflects part of the light that is about to leak from the rear end surface 212e, and returns this reflected light to the inside of the light guide 212.

  The light guide 212 of the light neutralizing device 210 of this example can also make the light intensity distribution of the light irradiated to the photosensitive drum 1 uniform over the entire area in the axial direction (longitudinal direction) of the photosensitive drum 1.

  In addition, a reflection film 213 is attached to the diffuse reflection surface 212c and the V-shaped groove 212f in the vicinity of the rear end portion of the light guide 212, and the light leaked from the diffusion reflection surface 212c by the reflection film 213 and leaked from the rear end surface 212e. Since a part of the light to be emitted is reflected and returned to the inside of the light guide 212, the amount of irradiation light from the light exit surface 212b in the vicinity of the rear end portion of the light guide 212 increases, and the irradiation light Can be made more uniform.

  In addition, the material and manufacturing method of the light guide 212 used in the light neutralizing device 210 of this example are the same as those in the above-described <Embodiment 1>.

<Embodiment 3>
FIG. 8 shows another example of the optical static eliminating device of the present invention.

  The optical static elimination device 310 of this example is a modification of the optical static elimination device of FIG. 4 and has a structure in which the light guide path portion 312f is folded, and light is incident between the light guide path portion 312f and the diffuse reflection surface 312c. Reflecting surfaces (total reflection surfaces) 312g and 312h for bending light incident on the surface 312a (light irradiated by the LED lamp 11) and guiding it to the diffuse reflection surface 312c are formed. The height H of the diffuse reflection surface 312c of the light guide 312c in this example with respect to the light exit surface 312b and the width of the diffuse reflection surface 312c are the same as those of the light guide 12 shown in FIG.

  Further, as shown in an enlarged view in FIG. 9, a steep inclined surface 312 i is formed at the rear end portion of the light guide 312, and the diffuse reflection surface 312 c and the inclined surface 312 i are formed in the vicinity of the rear end portion of the light guide 312. A reflective film 313 which has been subjected to aluminum vapor deposition or the like is attached. The reflection film 313 on the diffuse reflection surface 312c reflects the light leaking from the diffuse reflection surface 312c and returns the reflected light to the inside of the light guide 312 via the diffuse reflection surface 312c. In addition, the reflective film 313 on the inclined surface 312 i reflects light that is about to leak from the rear end of the light guide 312 and returns the reflected light to the inside of the light guide 312.

  According to the optical static elimination device 310 of this example, the optical path length of the static elimination region can be increased without increasing the length of the light guide 312 in the optical axis direction. As a result, the image forming apparatus can be reduced in size.

  Further, a reflection film 313 is attached to the diffuse reflection surface 312c and the inclined surface 312i in the vicinity of the rear end portion of the light guide body 312, and the light leaked from the diffusion reflection surface 312c by this reflection film 313 and leak from the rear end. Is reflected back to the inside of the light guide 312, the amount of light emitted from the light exit surface 312 b in the vicinity of the rear end of the light guide 312 is increased, and the light amount distribution of the irradiated light is further increased. It can be made uniform.

  In addition, the material and manufacturing method of the light guide 312 used in the light neutralizing device 310 of this example are the same as those in the above-described <Embodiment 1>.

  Here, in the example of FIG. 8, the light guide path portion 312 f is folded back, but the structure is not limited to this, and the light guide path portion 312 f extends along the direction intersecting the diffuse reflection surface 312 c ( (Substantially L-shaped structure)

<Embodiment 4>
Another example of the optical static eliminating device of the present invention is shown in FIGS.

  The light static elimination device 410 of this example is provided with a first reflection part R1 and a second reflection part R2 with the light guide 412 folded back, and the first reflection part R1 and the second reflection part R2 respectively. Between the point where the diffuse reflection surfaces (prism surfaces) 412c and 422c that reflect the light from the LED lamp 11 toward the photosensitive drum 1 (see FIG. 3) are formed, and between the two diffuse reflection surfaces 412c and 422c, Reflecting surfaces (total reflection surfaces) 412g and 412f are formed for bending the optical path and guiding the light that has passed through the first reflecting portion R1 to the second reflecting portion R2.

  The diffuse reflection surfaces 412c and 422c have heights H1 and H2 with respect to the light exit surface 412b of the light guide 412 and widths W1 and W2 of the diffuse reflection surfaces 412c and 422c (in the axial direction of the photosensitive drum 1). The length in the direction orthogonal to each other is formed so as to decrease at a constant ratio toward the rear end surface 412e of the light guide 412 according to the distance from each LED light source 11. Further, the two diffuse reflection surfaces 412c and 422c are formed in such an arrangement that the light traveling directions are opposite to each other.

  In addition, a reflective film 413 with aluminum vapor deposition or the like is attached to the diffuse reflection surface 422c in the vicinity of the rear end portion of the light guide 412. The reflective film 413 reflects the light leaking from the diffuse reflection surface 422c and returns the reflected light to the inside of the light guide 412 through the diffuse reflection surface 422c.

  In addition, in the light guide 412 of FIG. 10, the back surface 412d of the first reflecting portion R1 and the back surface 422d of the second reflecting portion R2 are inclined, and the light exit surface of the terminal portion of the first reflecting portion R1 The height with respect to 412b is substantially equal to the height with respect to the light emitting surface 412b of the front end portion of the second reflecting portion R2.

  According to the light neutralizing device 410 of this example, the region where the amount of reflected light by the one diffuse reflection surface 412c (or the diffuse reflection surface 422c) formed on the light guide 412 is small is changed to the other diffuse reflection surface 422c (or Since the light reflected by the diffuse reflection surface 412c) can be supplemented, the total light quantity distribution in the axial direction of the photosensitive drum 1 can be made uniform.

  Further, in the vicinity of the rear end portion of the light guide 412, a reflective film 413 is attached to the diffuse reflection surface 422 c, and the light leaking from the diffuse reflection surface 422 c is reflected by this reflection film 413 and returned to the inside of the light guide 412. As a result, the amount of light emitted from the light exit surface 412b near the rear end of the light guide 412 increases, and the light amount distribution of the irradiated light can be made more uniform.

  In addition, the material and manufacturing method of the light guide 412 used in the light neutralizing device 410 of this example are the same as those in the above-described <Embodiment 1>.

  Examples of the present invention will be described below together with comparative examples.

  3 and 4, the thickness of the light guide 12 is 3 mm, the length of the diffuse reflection surface 12 c is 300 mm, and the height of the diffuse reflection surface 12 c relative to the light exit surface 12 b (light guide height). ) H is constant from the front end (X = 0) to X = 125 mm (H = 8 mm) of the diffuse reflection surface 12c, as shown in FIG. 12A, and the diffuse reflection surface 12c from the position of X = 125 mm. The distance up to the rear end (X = 300 mm) was changed (decreased) at a constant ratio in the range of 8 mm to 4.2 mm. Further, as shown in FIG. 12B, the width W of the diffuse reflection surface 12c is constant within a range of 4.5 mm to 3 mm from the front end portion (X = 0) of the diffuse reflection surface 12c to X = 50 mm. The ratio between the position of X = 50 mm and the rear end (X = 300 mm) from the position of X = 50 mm is changed (increased) in the pattern shown in the figure in the range of 3 mm to 4 mm. It was.

  Then, as shown in FIG. 13A, the light guide 12 that is not subjected to any processing in the vicinity of the rear end is used as Comparative Example 1, and the reflection film 13 is formed on the upper surface in the vicinity of the rear end as shown in FIG. The pasted light guide 12 is taken as Example 1, and a V-shaped groove 12f is formed on the upper surface in the vicinity of the rear end as shown in FIGS. 13C, 13D, and 13E, and the reflective film 13 is pasted. The attached light guide 12 is set to Examples 2, 3, and 4. As shown in FIG. 13 (f), the light guide 12 with the inclined surface 12i formed at the rear end and the reflective film 13 attached thereto is used. Example 5 is adopted.

  The inclination angle θ of one surface 12g of the V-shaped groove 12f in the second to fourth embodiments is an angle that is inclined downward with respect to the upper surface of the light guide 12 as shown in FIG. In Example 3, the inclination angle θ is set to 45 degrees, and in Example 4, the inclination angle θ is set to 15 degrees. In any of Examples 2 to 4, the depth of the V-shaped groove 12f is set to 1 mm. In the fifth embodiment, the inclination angle θ is set to 45 degrees.

  The table in FIG. 15 shows the specifications in the vicinity of the rear end of the light guide 12 for each of the comparative example and Examples 1 to 5.

  FIG. 16 is a graph showing the light intensity distribution characteristics of light irradiated from the light exit surface 12b when light is incident on the light incident surface 12a of the light guide 12 from the LED lamp 11 according to the comparative example and Examples 1 to 5. The horizontal axis indicates the distance from the LED lamp 11 to the light irradiation position, and the vertical axis indicates the light intensity. FIG. 17 is a graph showing normalized light intensity distribution characteristics of the comparative example and Examples 1 to 5 based on the light intensity distribution characteristics of the comparative example.

  In the graphs of FIGS. 16 and 17, the light intensity distribution characteristic of the comparative example is indicated by H, the light intensity distribution characteristic of Example 1 is indicated by J1, the light intensity distribution characteristic of Example 2 is indicated by J2, and the example The light intensity distribution characteristic of No. 3 is indicated by J3, the light intensity distribution characteristic of Example 4 is indicated by J4, and the light intensity distribution characteristic of Example 5 is indicated by J5.

  In the graphs of FIGS. 16 and 17, the distance of 10 mm to 300 mm on the horizontal axis corresponds to the image forming area of the photosensitive drum 1, and the vicinity of the distance of 300 mm is the vicinity of the rear end portion of the light guide 12. . In this image forming area, if the light intensity of the light irradiation light from the light guide 12 is equal to or higher than the threshold value k (shown in FIG. 16), the photosensitive drum 1 can be sufficiently discharged, and image unevenness or the like can be obtained. You can get no good quality images.

  Further, FIG. 18 is a bar graph showing the light intensity in the vicinity of a distance of 300 mm for each of the comparative example and Examples 1 to 5.

  As is apparent from the graphs of FIGS. 16 to 18, the light intensity distribution characteristics H of the comparative example and the light intensity distribution characteristics J1 to J5 of Examples 1 to 5 have the maximum light intensity in the distance range of 50 mm to 100 mm. The light intensity gradually decreases as the distance increases.

  Then, the light intensity distribution characteristic H of the comparative example decreases in the vicinity of the distance of 300 mm, that is, in the vicinity of the rear end portion of the light guide 12 until the light intensity becomes less than the threshold value k. Therefore, when the light guide 12 of the comparative example is used, the photosensitive drum 1 cannot be sufficiently neutralized near a distance of 300 mm, and image unevenness occurs.

  Further, in the light intensity distribution characteristic J1 of Example 1, the light intensity slightly exceeds the threshold value k even in the vicinity of the distance of 300 mm, that is, in the vicinity of the rear end portion of the light guide 12. Therefore, when the light guide 12 of the first embodiment is used, the photosensitive drum 1 can be neutralized even in the vicinity of a distance of 300 mm, and image unevenness does not occur.

  Furthermore, in the light intensity distribution characteristics J2 to J5 of Examples 2 to 5, the light intensity sufficiently exceeds the threshold value k even in the vicinity of the distance of 300 mm, that is, in the vicinity of the rear end portion of the light guide 12. Therefore, when the light guide 12 of Examples 2 to 5 is used, the photosensitive drum 1 can be reliably discharged even in the vicinity of a distance of 300 mm, and image unevenness or the like does not occur.

  As is clear from the comparison between the comparative example and Examples 1 to 5, the reflective film 13 is attached to the upper surface of the rear end portion of the light guide 12 or the V shape is formed in the vicinity of the rear end of the light guide 12. If the groove 12f is formed and the reflective film 13 is attached, or the inclined surface 12i is formed at the rear end of the light guide 12 and the reflective film 13 is attached, the vicinity of the rear end of the light guide 12 is formed. Light intensity increases. For this reason, the photosensitive drum 1 can be reliably discharged even in the vicinity of a distance of 300 mm.

  The present invention relates to a photostatic discharge device that removes residual charges on a photoreceptor by light irradiation in an electrophotographic image forming process, and an image forming apparatus such as a copier equipped with the photostatic discharge device. In addition, it can be effectively used to make the light quantity distribution of the irradiation light irradiated to the photosensitive member uniform.

1 is a diagram illustrating a configuration of an embodiment of an image forming apparatus of the present invention. It is a figure which shows the structure of the image forming unit used for the image forming apparatus of FIG. It is a perspective view which shows the principal part structure of embodiment of the optical static elimination apparatus of this invention. It is a figure which writes and shows the side view (A) and top view (B) of the optical static elimination apparatus of FIG. It is a figure which shows the state which mounted | wore the image forming apparatus with the optical static elimination apparatus of FIG. It is a figure which writes and shows both the side view (A) and top view (B) which show the other example of the optical static elimination apparatus of this invention. It is a side view which expands and shows the rear-end vicinity of the light guide of FIG. It is a side view which shows another example of the optical static elimination apparatus of this invention. It is a side view which expands and shows the rear-end vicinity of the light guide of FIG. It is a figure which writes and shows both the side view (A) and top view (B) which show another example of the optical static elimination apparatus of this invention. It is a DD arrow line view of FIG. It is explanatory drawing of Example 1 of this invention. It is a side view which shows roughly the rear end part vicinity of a light guide separately for the comparative example 1 and Examples 1-5. It is explanatory drawing of the angle of the surface of the rear-end part of a light guide. It is a graph which shows the specification of the rear-end part vicinity of a light guide separately for the comparative example 1 and Examples 1-5. It is a graph which shows the light intensity distribution characteristic of the light irradiation light from a light guide according to a comparative example and Examples 1-5. It is a graph which normalizes and shows the light intensity distribution characteristic of FIG. It is a bar graph which shows the light intensity in the vicinity of the distance of 300 mm from LED according to the comparative example and Examples 1 to 5. It is a perspective view which shows the structure of the LED array used for the conventional optical static elimination apparatus. It is a side view which shows the structure of the conventional optical static elimination apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging device 3 Developing device 4 Transfer device 5 Cleaning device 10 Light neutralization device 11 LED lamp 12 Light guide 12a Light incident surface 12b of light guide 12b Light output surface of light guide 12c Diffuse reflection surface 12d Light guide Back surface of body 12e Rear end surface of light guide 20 Process cartridge 21 Front frame of image forming apparatus main body 22 Rear frame of image forming apparatus main body 23 Cartridge guide member 100 Image forming apparatus 101 Image reading unit 110 Optical system unit 111 First mirror Base 112 Second mirror base 113 Lamp reflector assembly 114 First reflecting mirror 115 Second reflecting mirror 116 Third reflecting mirror 117 Optical lens 118 CCD
DESCRIPTION OF SYMBOLS 102 Image formation part 120 Image formation unit 121 Exposure unit 103 Paper feed part 131,132,133 Paper cassette 134 Manual feed tray 135 Duplex unit 136 Switchback conveyance path 137 Paper discharge roller 104 Post-processing device 141 Lifting tray 105 Document placement stand 106 Both sides Automatic document feeder (RADF)
107 Fixing device

Claims (7)

  An optical static eliminator used to neutralize charges on a photoconductor in an electrophotographic image forming apparatus, a light guide disposed opposite to the photoconductor, and a light incident surface of the light guide A light source that emits light, and the light guide has a diffuse reflection surface that reflects light from the light source toward the photoconductor, and the diffuse reflection surface of the light guide The height with respect to the light emitting surface to the body and the width of the diffuse reflection surface change according to the distance from the light source, and a reflecting member is disposed on the upper surface in the vicinity of the terminal portion of the light guide. An optical static eliminator.   An optical static eliminator used to neutralize charges on a photoconductor in an electrophotographic image forming apparatus, a light guide disposed opposite to the photoconductor, and a light incident surface of the light guide A light source that emits light, and the light guide has a diffuse reflection surface that reflects light from the light source toward the photoconductor, and the diffuse reflection surface of the light guide The height with respect to the light emitting surface to the body and the width of the diffuse reflection surface change according to the distance from the light source, and a groove is formed across the light guide on the upper surface near the terminal end of the light guide. An optical static eliminator characterized by comprising:   The light neutralizing apparatus according to claim 2, wherein a reflection member is disposed on an upper surface in the vicinity of a terminal end portion of the light guide and an inner surface of a groove that crosses the light guide.   An optical static eliminator used to neutralize charges on a photoconductor in an electrophotographic image forming apparatus, a light guide disposed opposite to the photoconductor, and a light incident surface of the light guide A light source that emits light, and the light guide has a diffuse reflection surface that reflects light from the light source toward the photoconductor, and the diffuse reflection surface of the light guide The light characterized in that the height of the light emitting surface to the body and the width of the diffuse reflection surface change according to the distance from the light source, and the terminal portion of the light guide has a steeply inclined surface. Static eliminator.   The light neutralizing apparatus according to claim 4, wherein a reflection member is disposed on the upper surface in the vicinity of the terminal end portion of the light guide and on the steep inclined surface.   The light according to any one of claims 1 to 5, wherein the light guide is folded back, and a reflection surface for folding the optical path of the light guide is provided at a folded portion of the light guide. Static eliminator.   7. An image forming apparatus in which image forming units including respective photoconductors are arranged in tandem, wherein each of the photoconductors is provided with the photostatic discharge device according to any one of claims 1 to 6. Forming equipment.

Images