JP2010210823A - Optical discharging apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To commonalize components of a light guide means to an optical discharging apparatus with different paper width. <P>SOLUTION: The optical discharging apparatus includes: an LED 21a arranged on the side of a photoreceptor drum 8 in which an electrostatic latent image is formed; and the light guide means 21b arranged opposite to the photoreceptor drum 8 along the longitudinal direction of the photoreceptor drum 8 and for guiding light radiated from the LED 21a to the surface of the photoreceptor drum 8, wherein the light guide means 21b has: a first light guide member 21b-1; and a second light guide member 21b-2 arranged between the LED 21a and the first light guide member 21b-1, and the first light guide member 21b-1 and the light guide means 21b are made into length corresponding to the paper width of fixed form size. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical static elimination device and an image forming apparatus.

  In an image forming apparatus such as a printer or a copying machine that employs an electrophotographic system, the entire surface of a photosensitive drum as an image holding member is charged to a predetermined potential, and then image exposure is performed in accordance with image information to perform electrostatic latent. An image is formed, and a toner (visible agent) is supplied to the electrostatic latent image to be visualized to form a toner image. The toner image is directly transferred onto a sheet (sheet) and then fixed by a fixing device. Alternatively, an image is formed by transferring the image onto a sheet via an intermediate transfer member and then fixing the image by a fixing device.

  In the image forming apparatus having such a configuration, the charge remaining on the photosensitive drum after the toner image transfer is once removed, and then the above-described charging for the next image formation is performed.

  This is because, when charging is performed without removing the residual charge in the previous image formation, the surface potential of the photosensitive drum is disturbed due to the residual charge. Therefore, the disturbance of the potential mainly in a low humidity environment. Causes “horizontal streaks” in halftone images, etc., and “drum positive ghosts” mainly occur due to differences in charged potential on the photosensitive drum, which is a detrimental effect on printed images. Because. In order to prevent such adverse effects such as “horizontal streaks” and “drum positive ghosts”, a photostatic discharge device is provided as a charge eliminating means, and the photosensitive drum is irradiated with light before the charging process to reduce residual charges. This is because removal is effective.

  In the light neutralizing device, a rod-shaped light guide means is disposed to face the photosensitive drum in order to guide light from a light source disposed on the side of the photosensitive drum to the surface of the photosensitive drum.

  Here, the maximum width of printable paper (recording medium) (hereinafter referred to as “recording medium width”) is determined for the image forming apparatus, and the length of the light guide means used in the light neutralizing device is also the recording medium. The one that fits the width is selected. Accordingly, the light guide means must be prepared in various lengths according to the recording medium width of the image forming apparatus, which inevitably increases the manufacturing cost.

  In addition, as a technique regarding an optical static elimination apparatus, it describes in patent 3652246, Unexamined-Japanese-Patent No. 10-1333026, Unexamined-Japanese-Patent No. 2002-44378, Unexamined-Japanese-Patent No. 2002-278395, Unexamined-Japanese-Patent No. 2006-113216, etc., for example. Is known.

Japanese Patent No. 36552246 JP 10-1333026 A JP 2002-44378 A JP 2002-278395 A JP 2006-113216 A

  The present invention has been made from the above technical background, and an object of the present invention is to provide a technique capable of sharing parts of the light guiding means with respect to the light neutralizing apparatuses having different recording medium widths.

  In order to solve the above-mentioned problems, an optical static elimination device according to a first aspect of the present invention includes a light source disposed on the side of an image carrier on which an electrostatic latent image is formed, and a longitudinal direction of the image carrier. And a light guide means for guiding the light emitted from the light source to the surface of the image support body. The light guide means includes a first light guide member and the light source. And a second light guide member disposed between the first light guide member and the first light guide member.

  According to a second aspect of the present invention, in the first aspect of the present invention, at least one of the first light guide member and the second light guide member, and the light guide means are recorded in a fixed size. It has a length corresponding to the width of the medium.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, at least one of the first light guide member and the second light guide member is arranged in a longitudinal direction of the image carrier. It has a cylindrical shape or a columnar shape that extends.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects of the present invention, the light guide means covers the first opening and the light source that opens toward the image carrier. And a case having a second opening that is opened.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the case is formed of a white resin.

  The invention according to claim 6 is the invention according to claim 4 or 5, wherein a holding projection for holding the light guide means on the case is formed at an edge of the first opening of the case. It is characterized by being.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the second light guide member has a shape in which a cross-sectional area decreases as the distance from the light source increases. It is characterized by that.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein a part of the second light guide member is arranged in the longitudinal direction of the image holding body. It is characterized by overlapping with the optical member.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein a boundary portion of the outer peripheral surface between the first light guide member and the second light guide member is a non-step shape. It is characterized by that.

  The invention according to claim 10 is the invention according to any one of claims 1 to 8, wherein the first light guide member and the second light guide member have a boundary portion between the first light guide member and the first light guide member. The outer diameter of the second light guide member is smaller than the outer diameter of the light guide member.

  The invention according to claim 11 is the invention according to any one of claims 1 to 7, wherein the first light guide member and the second light guide member are spaced apart from each other. It is characterized by that.

  According to a twelfth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the image carrier is provided at a boundary portion between the first light guide member and the second light guide member. A light amount reducing member for reducing the amount of light guided to is provided.

  According to a thirteenth aspect of the present invention, in the invention of the twelfth aspect, the light amount reducing member is formed on an edge of the first opening of the film having light transmittance or the case. It is a holding projection for holding the light means on the case.

  According to a fourteenth aspect of the present invention, there is provided an image forming apparatus according to any one of the first to thirteenth aspects of the present invention, and the surface of the light static eliminator and the light guiding means of the light static eliminator disposed opposite to each other. An image forming unit provided with an image holding body on which a latent image is formed and detachably attached to the apparatus main body, wherein at least one of the first light guide member and the second light guide member is the image It is attached to the forming unit.

  According to the first aspect of the present invention, it is possible to make the light guide means common to the light neutralizing apparatus having different recording medium widths.

  According to the second aspect of the present invention, it is possible to make the light guide means common to the light neutralizing device having a standard size recording medium width.

  According to the third aspect of the present invention, compared to the case of the axially asymmetric shape, it is less affected by the mounting position accuracy, and the amount of light applied to the image carrier is stabilized.

  According to the fourth aspect of the present invention, the amount of light applied to the image carrier increases as compared with the case where the present invention is not adopted.

  According to the fifth aspect of the present invention, the amount of light applied to the image carrier increases as compared with the case where the case is other than white.

  According to invention of Claim 6, it is prevented that a light guide means falls from a case and is damaged or damaged.

  According to the seventh aspect of the present invention, fluctuations in the amount of light in the axial direction of the image carrier are alleviated compared to the case where the present invention is not adopted.

  According to the eighth aspect of the present invention, the variation in the amount of light in the axial direction of the image carrier is reduced as compared with the case where the present invention is not adopted.

  According to the ninth aspect of the present invention, compared to the case where the present invention is not adopted, an increase in the amount of light at the boundary portion is suppressed, and fluctuations in the amount of light in the axial direction of the image carrier are mitigated.

  According to the tenth aspect of the present invention, compared to a case where the present invention is not adopted, an increase in the amount of light at the boundary portion is suppressed, and fluctuations in the amount of light in the axial direction of the image carrier are alleviated.

  According to the eleventh aspect of the present invention, compared to the case where the present invention is not adopted, a steep change in the amount of light at the boundary portion between the first light guide member and the second light guide member is suppressed, and image retention is performed. Variations in the amount of light in the axial direction of the body are alleviated.

  According to the twelfth aspect of the present invention, compared with the case where the present invention is not adopted, a steep change in the amount of light at the boundary portion between the first light guide member and the second light guide member is suppressed, and image holding is performed. Variations in the amount of light in the axial direction of the body are alleviated.

  According to the invention of claim 13, compared to the case where the present invention is not adopted, a steep change in the amount of light at the boundary portion between the first light guide member and the second light guide member can be achieved with a simple structure. Can be suppressed.

  According to the invention described in claim 14, the assembly efficiency of the image forming apparatus is improved as compared with the case where the present invention is not adopted.

1 is a conceptual diagram of a tandem type color printer that is an image forming apparatus as an embodiment of the present invention. FIG. FIG. 2 is a conceptual diagram of a light static eliminator of the present embodiment mounted on the image forming apparatus of FIG. FIG. 2 is an exploded perspective view of the light static eliminator of the present embodiment mounted on the image forming apparatus of FIG. 1. FIG. 4 is a cross-sectional view taken along line A-A ′ of FIG. 3. It is a figure which shows the optical path of the light irradiated from LED in the light static elimination apparatus of this Embodiment. It is a perspective view which shows the photoconductor unit with which the optical static elimination apparatus of this Embodiment was mounted | worn. FIG. 7 is a perspective view showing an image forming unit to which the photosensitive unit of FIG. 6 is attached. It is a figure which shows the optical path of the light irradiated from LED in the optical static elimination apparatus as a modification of this Embodiment. It is a figure which shows the optical path of the light irradiated from LED in the light static elimination apparatus of a comparative example. It is a graph which shows the relationship between the distance from the edge part by the side of LED in a light static elimination apparatus, and light quantity. It is a conceptual diagram of the optical static elimination apparatus as a modification of this Embodiment. It is a conceptual diagram of the optical static elimination apparatus as a modification of this Embodiment. It is a conceptual diagram of the optical static elimination apparatus as a modification of this Embodiment. It is a conceptual diagram of the optical static elimination apparatus as a modification of this Embodiment. It is a conceptual diagram of the optical static elimination apparatus as a modification of this Embodiment. It is a conceptual diagram of the optical static elimination apparatus as a modification of this Embodiment.

  Hereinafter, an embodiment as an example of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

  FIG. 1 is a conceptual diagram of a tandem type color printer as an image forming apparatus according to an embodiment of the present invention. This color printer is configured to execute a printing operation based on image data sent from, for example, a personal computer or a scanner. Of course, the image forming apparatus may be configured as a copier or facsimile provided with a scanner, or a multifunction machine provided with these functions.

  In FIG. 1, an image forming unit 2 is arranged in a vertical direction in a substantially central portion of a tandem type color printer main body (an example of an apparatus main body) 1. Further, inside the color printer main body 1, a recording medium on which toner images of a plurality of colors formed by the image forming unit 2 are transferred is adsorbed to one side (left side in the illustrated case) of the image forming unit 2. A sheet conveyance belt unit 3 that conveys the sheet in a state is disposed, and a control unit 4 that includes a control circuit or the like is disposed on the other side of the image forming unit 2 (on the right side in the drawing). A power supply circuit unit 5 having a high-voltage power supply circuit and the like is disposed above.

  In addition, a paper feed cassette 6 that houses and feeds paper 18 or the like as a recording medium on which an image is transferred is disposed at the bottom of the color printer main body 1.

  The image forming unit 2 includes four image forming units 7Y, 7M, 7C, and 7K that form toner images of yellow (Y), magenta (M), cyan (C), and black (K) in order from the bottom. These four image forming units 7Y, 7M, 7C, and 7K are arranged in series at regular intervals along the vertical direction.

  These four image forming units 7Y, 7M, 7C, and 7K are configured in the same manner except for the color of the image to be formed, and roughly divided, as shown in FIG. 1, holds an image that rotates at a predetermined rotation speed. Photosensitive drum 8 (8Y, 8M, 8C, 8K), and a charging roll 9 (9Y, 9M, 9C, 9K) for primary charging that uniformly charges the surface of the photosensitive drum 8 to a predetermined potential. An exposure device 10 (10Y, 10M, 10C, 10K) that exposes an image corresponding to each color on the surface of the photosensitive drum 8 to form an electrostatic latent image, and a static image formed on the photosensitive drum 8. A developing device 11 (11Y, 11M, 11C, 11K) that develops the electrostatic latent image with a corresponding color toner, and a photostatic device 21 (21Y, 21M, 21) that removes the charge remaining on the photosensitive drum 8 after development. 21C, 21K) and the photosensitive drum 8 A cleaning device 12 for cleaning the transfer residual toner remaining (12Y, 12M, 12C, 12K) and supplies the toner to the developing device 11 toner cartridge 13 is configured from (13Y, 13M, 13C, 13K) and.

  As shown in FIG. 1, the developing device 11 supplies two-component or one-component developer contained therein to the developing roll 14 (14Y, 14M, 14C, 14K) while stirring, and the developing roll 14 While controlling the layer thickness of the developer supplied to the photosensitive drum 8, the developer is conveyed to a developing area facing the photosensitive drum 8, and the electrostatic latent image formed on the surface of the photosensitive drum 8 is formed with toner of a predetermined color. It is comprised so that it may develop.

  The yellow (Y), magenta (M), cyan (C), and black (K) developing devices 11Y, 11M, 11C, and 11K correspond to yellow (Y), magenta (M), and cyan (M). C) and toner cartridges 13Y, 13M, 13C, and 13K as developer containers for supplying toner of each color of black (K).

  The light neutralizing device 21 removes residual charges after development by irradiating the photosensitive drum 8 with light so that the drum surface is uniformly charged in the next image formation.

  Further, as shown in FIG. 1, the cleaning device 12 removes the transfer residual toner remaining on the surface of the photosensitive drum 8 with a cleaning blade 15 (15Y, 15M, 15C, 15K), and the removed transfer residual toner. The cleaning device 12 is transported and accommodated inside.

  As shown in FIG. 1, a control unit 4 is disposed inside the color printer main body 1, and the control unit 4 includes, for example, an image processing device 16 that performs predetermined image processing on image data. Is provided. The image processing device 16 sequentially outputs image data of each color of yellow (Y), magenta (M), cyan (C), and black (K) to the exposure device 10, and the exposure device 10 according to the image data. The four laser beams emitted in this manner are scanned and exposed on the respective photosensitive drums 8Y, 8M, 8C, and 8K to form electrostatic latent images. The electrostatic latent images formed on the photosensitive drums 8Y, 8M, 8C, and 8K are respectively yellow (Y), magenta (M), cyan (C), and black by the developing devices 11Y, 11M, 11C, and 11K. It is developed as a toner image of each color of (K).

  Further, the paper transport belt unit 3 includes an endless paper transport belt 17 that circulates and moves. The paper transport belt 17 is yellow (Y) formed by the image forming units 7Y, 7M, 7C, and 7K. , Magenta (M), cyan (C), and black (K) toner images of respective colors are transferred, and the sheet 18 as a recording medium is conveyed in an electrostatically attracted state.

  As shown in FIG. 1, the paper transport belt 17 is stretched with a predetermined tension between a drive roll 19 and a driven roll 20 as stretch rolls arranged along the vertical direction. A drive roll 19 that is rotationally driven by a motor is configured to circulate counterclockwise in FIG. 1 at a predetermined speed.

  For example, the distance between the drive roll 19 and the driven roll 20 is set to a length substantially equal to the length of the A3 size paper 18, but is not limited thereto, and may be set arbitrarily. As the paper transport belt 17, for example, a flexible synthetic resin film such as polyimide is formed in an endless belt shape.

  Further, as shown in FIG. 1, an attracting roll 22 for electrostatically attracting the paper 18 to the surface of the paper transport belt 17 is brought into contact with the surface of the drive roll 19 via the paper transport belt 17. Is arranged. The suction roll 22 is configured, for example, by covering the surface of a metal cored bar with conductive rubber in the same manner as the charging rolls 9 of the image forming units 7Y, 7M, 7C, and 7K. A predetermined bias voltage for adsorption is applied. The suction roll 22 is configured to electrostatically charge the paper 18 sent from the paper feed cassette 6 and suck the paper 18 on the surface of the paper transport belt 17. Note that the suction roll 22 is not necessarily provided.

  Toner of each color of yellow (Y), magenta (M), cyan (C), and black (K) formed on the photosensitive drums 8Y, 8M, 8C, and 8K of the image forming units 7Y, 7M, 7C, and 7K As shown in FIG. 1, the images are sequentially transferred in multiple layers onto the sheet 18 conveyed while being attracted to the surface of the sheet conveying belt 17 while being superimposed on each other by the transfer rolls 23Y, 23M, 23C, and 23K. Is done. The transfer rolls 23Y, 23M, 23C, and 23K are integrally attached to the paper transport belt unit 3.

  As shown in FIG. 1, the paper 18 is fed from a paper feed cassette 6 disposed at the bottom of the printer main body 1 and conveyed to the printer main body 1. The paper feed cassette 6 includes a paper tray 24 in which paper 18 having a desired size and material is accommodated. In addition, a pickup roll 35 that nips the uppermost sheet 18 is disposed immediately above the sheet tray 24. As a result, the paper 18 of a desired size and material is taken out from the paper tray 24 one by one by the pickup roll 35 and fed by the feeding roll 25 and separated one by one by the separating roll 26. The sheet is fed in a state, and is conveyed to a suction position on the sheet conveying belt 17 at a predetermined timing via a registration roll 27 as a sheet feeding unit.

  The feeding roll 25 and the pickup roll 35 are provided on the color printer main body 1 side, and the separating roll 26 is provided on the paper feeding cassette 6 side.

  Here, a roll that combines the function of the pickup roll 35 and the function of the feeding roll 25 may be used. Further, instead of the separating roll 26, a pad type separating means having a predetermined friction resistance with respect to the paper 18 to be taken out may be used.

  As shown in FIG. 1, the paper 18 on which the toner images of each color of yellow (Y), magenta (M), cyan (C), and black (K) are transferred in a multiple manner has a rigidity ( After being separated from the paper transport belt 17 by so-called stiffness, the paper is transported along the transport path 28 to the fixing device 29. The fixing device 29 applies heat and pressure to the paper 18 to fix the toner image on the paper 18.

  The paper transport belt 17 and the fixing device 29 are arranged close to each other, and the paper 18 separated from the paper transport belt 17 is transported to the fixing device 29 by the transport force of the paper transport belt 17. The fixing device 29 is rotationally driven in a state in which the heating roll 30 and the pressure belt 31 are in pressure contact with each other, and the sheet 18 is passed through a nip portion formed between the heating roll 30 and the pressure belt 31. The fixing process is performed by heat and pressure.

  Thereafter, the paper 18 on which the toner images of the respective colors are fixed is discharged with a pair of discharge rolls 32 onto a discharge tray 33 provided at the top of the color printer main body 1 with the print surface facing down, and the printing operation is performed. finish.

  Note that a color printer can print an image of a desired color such as monochrome as well as a color image. Yellow (Y), magenta (M), magenta (M), and the like can be printed according to the color of the image to be printed. A toner image is formed by all or part of the cyan (C) and black (K) image forming units 7Y, 7M, 7C, and 7K.

  In FIG. 1, reference numeral 34 denotes an operation panel provided with a display unit such as a liquid crystal panel attached to the front of the printer main body 1. The operation panel 34 displays the status of the printer and is necessary. It is configured to perform operations and the like.

  Now, the photostatic device 21 of the image forming apparatus of the present embodiment is a device that optically removes the residual charge of the photosensitive drum 8 by light irradiation. As shown in FIG. 2, a cylindrical shape made of aluminum. Is disposed on the side of the photosensitive drum 8 provided with a photosensitive layer 8b made of an optical semiconductor such as OPC (Organic Photo Conductor) on the entire outer periphery of the substrate 8a. LED (an example of a light source) 21a that emits light.

  The light neutralizing device 21 has light guide means 21b made of plastic such as ABS resin along the longitudinal direction of the photosensitive drum 8, and has a predetermined distance (for example, 8 mm) from the photosensitive drum 8. ) Are placed facing each other.

  Here, the LED 21a as the light source is manufactured by, for example, mounting an LED chip on a metal lead and sealing the portion with a transparent resin, and one end side in the longitudinal direction of the light guide means 21b. Is arranged. The light emitted from the LED 21a is incident on the end surface of the light guide unit 21b, and then is appropriately scattered and reflected to be guided to the surface of the photosensitive drum 8. The LED 21a uses a wavelength that matches the photosensitivity of the photosensitive layer 8b of the photosensitive drum 8.

  As shown in FIG. 2 and FIG. 3, the light guide means 21b includes a first light guide member 21b-1 and a second light guide disposed between the first light guide member 21b-1 and the LED 21a. It is comprised from the two light guide members of the optical member 21b-2. The first light guide member 21b-1 has a cylindrical shape extending in the longitudinal direction of the photosensitive drum 8, and is made of a transparent resin such as an acrylic resin, a polycarbonate resin, a polystyrene resin, or an ABS resin, and has a predetermined length. Consists of cut extruded products. The second light guide member 21b-2 has a cylindrical shape extending in the longitudinal direction of the photosensitive drum 8, and is made of, for example, a transparent resin made of the same material as or different from the first light guide member 21b-1. It is also composed of an extrusion molded product cut to a predetermined length.

  And since the light guide means 21b is comprised by the 1st light guide member 21b-1 and the 2nd light guide member 21b-2 in this way, the 1st light guide member 21b-1 is from LED21a. The light incident through the second light guide member 21b-2 is guided to a part of the photosensitive drum 8 in the longitudinal direction. The second light guide member 21 b-2 guides the light from the LED 21 a to the first light guide member 21 b-1 and guides the remaining portion (other part) in the longitudinal direction of the photosensitive drum 8.

  As will be described later, since the first light guide member 21b-1 and the second light guide member 21b-2 may be partially overlapped in the longitudinal direction of the photosensitive drum 8, the second guide The optical member 21b-2 may guide light to a portion overlapping the first light guide member 21b-1 of the photosensitive drum 8. In other words, the second light guide member 21 b-2 only needs to guide light to at least another part of the photosensitive drum 8 in the longitudinal direction.

  The first light guide member 21b-1 has an outer diameter of, for example, 5 mm and an inner diameter of, for example, 3 mm. Further, the second light guide member 21b-2 has an outer diameter of, for example, 5 mm, which is the same as the outer diameter of the first light guide member 21b-1. In addition, the outer diameter of LED21a is 5 mm which is the same as the outer diameter of these light guide members 21b-1, 21b-2, for example. However, these dimensions are merely examples, and the present invention is not limited to these numerical values. The incident-side end surfaces of the first light guide member 21b-1 and the second light guide member 21b-2 (the end surfaces of the first light guide member 21b-1 on the second light guide member 21b-2 side, and The surface of the second light guide member 21b-2 on the LED 21a side is roughened, and the roughness Rz is, for example, 3 μm or more (preferably 15 μm or more).

  Here, the length of the first light guide member 21b-1 corresponds to the vertical width of A4 (210 mm × 297 mm) which is a standard size paper (standard size recording medium). Also, the combined length of the first light guide member 21b-1 and the second light guide member 21b-2 corresponds to the vertical width of A3 (297 mm × 420 mm), which is also a regular size paper. Yes.

  As described above, in the present embodiment, the first light guide member 21b-1 corresponds to the vertical width of A4, but the second light guide member 21b-2 has a vertical width of A4. The first light guide member 21b-1 or the second light guide member 21b-2 may correspond to the lateral width of A4. Further, the length of the first light guide member 21b-1, the length of the second light guide member 21b-2, and the first light guide member 21b-1 and the second light guide member 21b-2. Any of the combined lengths (that is, the length of the light guide unit 21b) may correspond to the sheet width of the standard size.

  For example, A0 to A10, B0 to B10, large full paper, full paper, half cut, A3 nobi, four cut, six cut wide, six cut, 2L, KG, postcard, L, bible There are envelopes of various sizes, various sizes, the length of the first light guide member 21b-1, the length of the second light guide member 21b-2, and the first light guide member 21b-1 and the second The combined length of the light guide member 21b-2 can correspond to the vertical width or the horizontal width of these sheets. Note that the paper is merely an example of a recording medium, and recording media of various materials such as thick paper such as plain paper and coated paper, and an OHP sheet are used.

  Here, the lengths of the first light guide member 21 b-1, the second light guide member 21 b-2, and the light guide means 21 b do not have to correspond to the fixed-size paper width. That is, the light guide means 21b is composed of the first light guide member 21b-1 and the second light guide member 21b-2, but the first light guide member 21b-1 and the second light guide. Neither the member 21b-2 nor the light guide means 21b may have a corresponding relationship with the paper width of the standard size.

  In the present embodiment, the first light guide member 21b-1 has a cylindrical shape and the second light guide member 21b-2 has a columnar shape. However, the first light guide member 21b-1 has a columnar shape. The second light guide member 21b-2 may be cylindrical, or both may be columnar or cylindrical. Furthermore, the shape may be various shapes such as a prism shape, a hollow prism shape, a cone shape, a pyramid shape, and a plate shape, instead of a cylindrical shape or a column shape. However, if it is an axial object shape such as a cylindrical shape, a cylindrical shape, a conical shape, a prefixed conical shape, or a shape in which these axial directions are matched, the influence of the mounting position accuracy is less than that of an axially asymmetric shape. Since it becomes difficult to receive, the amount of light applied to the photosensitive drum 8 is stabilized.

  As shown in FIGS. 2 and 3, a case 21c is provided so as to cover the light guide means 21b. The case 21c is made of a white resin such as an acrylic resin, a polycarbonate resin, a polystyrene resin, or an ABS resin. The inner peripheral surface 21c-a is curved in a concave shape, and the inner peripheral surface 21c-a is disposed so as to face the photosensitive drum 8. The case 21c is formed with a first opening 21c-1 that opens toward the photosensitive drum 8, and a second opening 21c-2 that opens toward the LED 21a. And LED21a is arrange | positioned at the 2nd opening part 21c-2 side so that inner peripheral surface 21c-a may be faced. A terminal wall 21c-b that is substantially perpendicular to the inner peripheral surface 21c-a is formed on the opposite side of the second opening 21c-2.

  And since the light guide means 21b is covered with such a case 21c, even the light reflected by the inner peripheral surface 21c-a which is the surface facing the light guide means 21b of the case 21c is directed to the photosensitive drum 8. As a result, the amount of light applied to the photosensitive drum 8 increases.

  Note that the case 21c may be formed of a material other than white resin. However, when the case 21c is formed of white resin as in the present embodiment, the light reflectance in the case 21c is improved, compared with the case where the case is made of a material other than white. As a result, the amount of light applied to the photosensitive drum 8 increases.

  As shown in FIGS. 3 and 4, at the edge of the first opening 21c-1 of the case 21c, the light guide means 21b (that is, the first light guide member 21b-1 and the second light guide member). A holding projection 21c-c for holding 21b-2) in the case 21c is formed. The holding projections 21c-c are formed as a pair at the mutually opposing edges of the first opening 21c-1, and project inward as shown in detail in FIG. Such holding projections 21c-c have two longitudinal positions where the first light guide member 21b-1 is mounted, and two longitudinal positions where the second light guide member 21b-2 is mounted. Are formed in a total of four locations. Therefore, the first light guide member 21b-1 and the second light guide member 21b-2 are held in the case 21c by the holding projections 21c-c at two positions. The simple structure of the holding protrusions 21c-c prevents the light guide means 21b from falling off the case 21c and being damaged or damaged. The holding protrusions are not limited to the four shown in the figure, and may be formed over the entire length of the edge of the first opening 21c-c.

  Here, in order to attach the first light guide member 21b-1 and the second light guide member 21b-2 to the case 21c, they are inserted from the second opening 21c-2, or the case 21c is elastic. By being pushed in from the first opening 21c-1 while being deformed (see FIG. 3).

  The light guiding means 21b and the case 21c are attached to a housing 2a-1 (FIG. 6) of a photoreceptor unit (image holding unit) 2a described later. The photosensitive unit 2a is detachably attached to the frame 2-1 (FIG. 7) of the image forming unit 2. On the other hand, the LED 21a is directly attached to the frame 2-1 of the image forming unit 2, not the photoreceptor unit 2a. However, it goes without saying that the LED 21a may also be attached to the photoreceptor unit 2a.

  In the light static elimination apparatus 21 having the above configuration, as shown in FIG. 5, the light emitted from the LED 21a is incident from the end face (incident end face) of the second light guide member 21b-2, and a part thereof is the second The light guide member 21 b-2 is directly guided to the surface of the photosensitive drum 8. Further, the other part comes out of the end surface opposite to the incident end surface of the second light guide member 21b-2 and reaches the first light guide member 21b-1, and the first light guide member 21b-1 or It passes through the internal space of the first light guide member 21 b-1 that has a cylindrical shape, is reflected by the first light guide member 21 b-1 or the case 21 c, and is guided to the surface of the photosensitive drum 8.

  Here, when the light passes through the internal space of the first light guide member 21b-1, the loss of light energy is small as compared with the case where the light passes through the individual of the first light guide member 21b-1. Therefore, the light passing through the inner space is suppressed in the attenuation of the light amount and proceeds in the direction of the end wall 21c-b of the case 21c. Thereby, it becomes easy to ensure the light quantity of the light irradiated to the photosensitive drum 88 even at a location away from the LED 21a.

  Further, when the end wall 21c-b is provided as in the present embodiment, the light is reflected by the end wall 21c-b and is reflected and transmitted while returning. Thereby, the light quantity of the light irradiated to the photosensitive drum 8 from the terminal wall 21c-b side increases.

  Then, the light remaining on the surface of the photosensitive drum 8 in this manner removes the charge remaining on the photosensitive drum 8 after the toner image transfer. Thereafter, the surface of the photosensitive drum 8 is uniformly charged to a predetermined potential by the charging roll 9 for forming a new image.

  Note that the arrows shown in FIG. 5 schematically indicate reflection or transmission. Therefore, the arrows in the figure do not accurately represent the relationship between the incident angle, the reflection angle, the refraction angle, or the path of all light. Actually, innumerable light is reflected or transmitted more than shown.

  In the present embodiment, since the first light guide member 21b-1 corresponds to the width (here, the vertical width) of A4 which is a standard size sheet, the first light guide member 21b- 1 can also be used independently for other light static eliminating devices having a fixed size paper width (that is, A4 width) corresponding to the length of the first light guide member 21b-1. As a result, the first light guide member 21b-1 can be used in an optical static eliminator with different widths of the standard size, so that the light guide means 21b can be made common and the manufacturing cost is reduced.

  In addition, when the 2nd light guide member 21b-2 respond | corresponds to the width | variety of A4, the 2nd light guide member 21b-2 can be used independently also for another optical static elimination apparatus. Therefore, the second light guide member 21b-2 can be used for an optical static elimination device having a sheet width with a different standard size.

  Further, when both the first light guide member 21b-1 and the second light guide member 21b-2 are compatible with the paper width of the standard size, any of the light guide members 21b-1, 21b- No. 2 can also be used for an optical static eliminating device having a sheet width of a different standard size.

  Here, as described above, the lengths of the first light guide member 21b-1, the second light guide member 21b-2, and the light guide means 21b may not correspond to the paper width of the standard size. Even in such a case, the first light guide member 21b-1 or the second light guide member 21b-2 can be used in an optical static elimination device having a specification that does not correspond to the paper width of the standard size. Therefore, it can be similarly used for an optical static eliminator with different paper widths, so that the light guide means 21b can be shared, and the manufacturing cost is reduced.

  In FIG. 6, a photosensitive unit (image holding unit) 2a corresponds to each of four image forming units 7Y, 7M, 7C, and 7K that form toner images of the respective colors. It has a housing 2a-1 made of resin. The photosensitive drum 8 constituting the image forming units 7Y, 7M, 7C, and 7K is rotatably attached to the housing 2a-1, and further includes a charging roll 9, a developing device 11, and a light neutralizing device 21. The light guiding means 21b and the case 21c, the cleaning device 12, and the toner cartridge 13 can be attached. Further, a collection path 40 for taking in the transfer residual toner collected by the cleaning device 12 into a waste toner box (not shown) is attached to the side of the housing 2a-1.

  Here, the light guide unit 21b does not necessarily have to be attached to the photoreceptor unit 2a, and the first light guide member 21b-1 and the second light guide member 21b-2 constituting the light guide unit 21b. Only one of these may be attached. However, the first light guide member 21b-1 or the second light guide member 21b-2 that is a constituent element of the light guide unit 21b or the light guide unit 21b constituting the light neutralizing device 21 is attached to the photoreceptor unit 2a. By doing so, the assembly efficiency of the image forming apparatus is improved.

  In FIG. 6, the light guide 21b, the charging roll 9, and the cleaning device 12 are hidden in the housing 2a-1. Further, the developing device 11 and the toner cartridge 13 are not shown.

  In FIG. 7, the image forming unit 2 has a frame 2-1. The four photoconductor units 2a (FIG. 6) provided corresponding to the development colors are detachably mounted on the frame 2-1 in the vertical direction. Accordingly, the light guide unit 21b or the first light guide member 21b-1 or the second light guide member 21b-2 that is a component of the light guide unit 21b is connected to the image forming unit 2 via the photosensitive unit 2a. It is attached.

  The first light guide member 21b-1 constituting the light guide means 21b of the light neutralizing device 21 in the present embodiment has a cylindrical shape and the second light guide member 21b-1 has a cylindrical shape. Thus, these light guide members 21b-1 and 21b-2 can take various other shapes.

  Here, as a light neutralization device of a modification in the present embodiment, the first light guide member 21b-1 has a cylindrical shape, the second light guide member 21b-2 has a conical shape, and the second light guide member 21b. FIG. 8 shows an optical static elimination device 21 in which a part on the sharp side of −2 overlaps with the first light guide member 21 b-1 in the longitudinal direction of the photosensitive drum 8.

  Moreover, as an optical static elimination apparatus of a comparative example, the optical static elimination apparatus 121 which has not the two light guide members like this Embodiment but the column-shaped single light guide means 121b is shown in FIG. In addition, as shown in FIG. 9, the positional relationship between the LED 121a and the case 121c is the same as that of the optical static elimination device 21 of the present embodiment.

  And the relationship between the distance from the edge part by the side of LED in these light static elimination apparatuses and light quantity (irradiation light quantity to the photosensitive drum 8) is shown in FIG. In addition, in the graph of FIG. 10, the first light guide member 21b-1 has a cylindrical shape, and the second light guide member 21b-2 has a columnar shape. An optical neutralization device 21 (see FIG. 8) in which the first light guide member 21b-1 has a cylindrical shape and the second light guide member 21b-2 has a conical shape is shown in “Embodiment 2”. Moreover, the light static elimination apparatus 121 (refer FIG. 9) of the cylindrical single light guide means 121b is shown by the "comparative example."

  As shown in FIG. 10, the light neutralizing device 21 of the first embodiment and the light static eliminating device 21 of the second embodiment both have a necessary light amount over the entire length, whereas the light neutralizing device 121 of the comparative example has an LED 121a. It can be seen that the amount of light is insufficient in front of the end on the opposite side.

  Now, in FIG. 10, comparing the characteristics of the optical static elimination device 21 of the first embodiment and the optical static elimination device 21 of the second exemplary embodiment, the optical static elimination device 21 of the first exemplary embodiment is the position of the second light guide member 21 b-2. However, the amount of light is less than that of the light neutralizing device 21 of the second embodiment, while the boundary between the first light guide member 21b-1 and the second light guide member 21b-2 is reversed. The amount of light is larger than that of the light neutralizing device 21.

  Here, the light neutralizing device 21 of the first embodiment has a light amount smaller than that of the light static eliminating device 21 of the second embodiment at the position of the second light guide member 21b-2. Since the second light guide member 21b-2 in the cylinder 21 is cylindrical, the light incident from the LED 21a is not diffused much on the outer peripheral surface of the second light guide member 21b-2, so that the first light guide member 21b- This is because it is guided to the end surface on the one side. On the other hand, in the light static elimination apparatus 21 of Embodiment 2, since the second light guide member 21b-2 has a conical shape and the cross-sectional area becomes smaller as the distance from the LED 21a increases, as shown in FIG. The light is diffused on the outer peripheral surface of the second light guide member 21b-2 to increase the amount of light.

  Moreover, the light static elimination apparatus 21 of Embodiment 1 has more light quantity than the optical static elimination apparatus 21 of Embodiment 2 in the boundary part of the 1st light guide member 21b-1 and the 2nd light guide member 21b-2. In the light neutralizing device 21 of the first embodiment, as described above, the first light guide member 21b-1 is not diffused so much on the outer peripheral surface of the cylindrical second light guide member 21b-2. This is because the light is guided to the end face on the side and diffuses at the end face. Therefore, in the light static elimination apparatus 21 of Embodiment 1, the light quantity is rapidly increased at the boundary portion between the first light guide member 21b-1 and the second light guide member 21b-2. On the other hand, in the light static elimination apparatus 21 of Embodiment 2, since light diffuses on the outer peripheral surface of the conical second light guide member 21b-2, an increase in the amount of light at the boundary portion is suppressed.

  Thus, if the second light guide member 21b-2 is formed in a conical shape so that the cross-sectional area decreases as the distance from the LED 21a increases, fluctuations in the amount of light in the axial direction of the photosensitive drum 8 are reduced. Here, the light quantity fluctuation is alleviated because the second light guide member 21b-2 may be shaped so that the cross-sectional area decreases as the distance from the LED 21a increases. A pyramid shape such as a pyramid may be used.

  Furthermore, in the light static elimination apparatus 21 of Embodiment 2, the increase in the amount of light at the boundary portion between the first light guide member 21b-1 and the second light guide member 21b-2 is suppressed. This is because a part of the optical member 21 b-2 overlaps the first light guide member 21 b-1 in the longitudinal direction of the photosensitive drum 8. That is, if both are overlapped, the diffusion and scattering of light at the boundary portion between the first light guide member 21b-1 and the second light guide member 21b-2 are suppressed. Thus, fluctuations in the amount of light in the axial direction of 8 are alleviated.

  In FIG. 8, the second light guide member 21 b-2 has a conical shape and a part thereof overlaps with the first light guide member 21 b-1, but it does not have to be conical and overlap. In this case, although the diffusion and scattering of light at the boundary portion are not suppressed as much as when they overlap, there is diffusion of light on the outer peripheral surface of the second light guide member 21b-2 due to the conical shape. This is because there is a suppression of an increase in the amount of light.

  Conversely, if a part of the first light guide member 21b-1 and the second light guide member 21b-2 overlap in the longitudinal direction of the photosensitive drum 8, the second light guide member 21b-2 is conical. Since fluctuations in the amount of light in the axial direction of the photosensitive drum 8 are alleviated without the shape, for example, as shown in FIG. 11, the second light guide member 21b-2 is coaxially arranged with two cylinders having different diameters. It is good also as a thing of the shape distribute | arranged to the structure which inserted the part of the small diameter cylinder in the 1st light guide member 21b-1.

  When the first light guide member 21b-1 has a cylindrical shape, one end of the second light guide member 21b-2 is inserted into the first light guide member 21b-1, and the second light guide member 21b-1 is inserted into the second light guide member 21b-1. A part of the light guide member 21 b-2 is overlapped with the first light guide member 21 b-1 in the longitudinal direction of the photosensitive drum 8, so that the attachment between them can be performed easily. Even if one member of the first light guide member 21b-1 and the second light guide member 21b-2 is not held by the case 21c, the light guide means 21b has a holding force by the other member. However, it is difficult to drop off from the case 21c.

  As described above, the first light guide member 21b-1 and the second light guide member 21b-2 can adopt various shapes. For example, as shown in FIGS. A shape in which no step is provided at the boundary portion of the outer peripheral surface between the first light guide member 21b-1 and the second light guide member 21b-2, that is, a non-step shape can be obtained. In FIG. 12, the outer diameter of the first light guide member 21b-1 on the second light guide member 21b-2 side is the same as the outer diameter of the other portions. In FIG. Although the outer diameter of the member 21b-1 on the second light guide member 21b-2 side is gradually reduced, all of them have a non-stepped shape.

  If there is a step at the boundary portion of the outer peripheral surface between the first light guide member 21b-1 and the second light guide member 21b-2, the light emitted from the second light guide member 21b-2 is transmitted to the first light guide member 21b-2. The light hits the step which is the vertical surface of the optical member 21b-1 and is reflected, thereby increasing the amount of light. However, since the light emitted from the second light guide member 21b-2 is incident on the first light guide member 21b-1 without being reflected in large quantities if it is a non-step shape, an increase in the amount of light at the boundary portion is suppressed. As a result, fluctuations in the amount of light in the axial direction of the photosensitive drum 8 are alleviated.

  A shape that can suppress an increase in the amount of light at the boundary portion even when there is a step is also conceivable. That is, as shown in FIG. 14, at the boundary portion between the first light guide member 21b-1 and the second light guide member 21b-2, the first light guide member 21b-1 is larger than the outer diameter R1. The outer diameter R2 of the second light guide member 21b-2 is smaller.

  When the outer diameter R2 of the second light guide member 21b-2 is larger than the outer diameter R1 of the first light guide member 21b-1, a part of the light emitted from the second light guide member 21b-2 Diffuses without entering the first light guide member 21b-1, and the amount of light increases. However, as shown in FIG. 14, if the outer diameter R2 of the second light guide member 21b-2 is smaller than the outer diameter R1 of the first light guide member 21b-1, the second light guide member 21b. Since the light emitted from -2 is incident on the first light guide member 21b-1, an increase in the amount of light at the boundary is suppressed, and fluctuations in the amount of light in the axial direction of the photosensitive drum 8 are alleviated.

  To suppress the amount of light at the boundary between the first light guide member 21b-1 and the second light guide member 21b-2, as shown in FIG. 15, the first light guide member 21b-1 and the second light guide member 21b-1 A space G may be provided between the light guide member 21b-2 and the light guide members 21b-2.

  In such a structure, a loss of light amount occurs in the separated portion (space G), so that the steep light amount at the boundary portion between the first light guide member 21b-1 and the second light guide member 21b-2 is reduced. The change is suppressed, and the fluctuation of the light amount in the axial direction of the photosensitive drum 8 is reduced.

  In order to suppress the amount of light at the boundary portion between the first light guide member 21b-1 and the second light guide member 21b-2, a light amount reduction that further reduces the amount of light guided to the photosensitive drum 8 at the boundary portion. A member may be provided.

  As the light quantity reducing member, as shown in FIG. 16, there is a film F having optical transparency. That is, the film F is arranged on the entire periphery of the boundary portion between the first light guide member 21b-1 and the second light guide member 21b-2 or partially on the photosensitive drum 8 side, or covers the boundary portion. By providing the case 21c as described above, the amount of light at the boundary portion is reduced. Further, as the light quantity reducing member, a holding projection 21c-c (FIGS. 3 and 4) is formed at the edge of the first opening 21c-1 of the case 21c to hold the light guide means 21b21b in the case 21c. is there. If the holding projection 21c-c is formed at the boundary between the first light guide member 21b-1 and the second light guide member 21b-2, the amount of light is reduced by the amount of light blocked by the holding projection 21c-c. Will do.

  If the film F and the holding projections 21c-c are applied as the light amount reducing member, the steep light amount at the boundary portion between the first light guide member 21b-1 and the second light guide member 21b-2 with a simple structure. The change of is suppressed.

  Although the invention made by the present inventor has been specifically described based on the embodiment, the embodiment disclosed in this specification is an example in all respects and is limited to the disclosed technology. Should not be considered. That is, the technical scope of the present invention should not be construed restrictively based on the description in the above-described embodiment, but should be construed according to the description of the scope of claims. All modifications are included without departing from the technical scope equivalent to the described technique and the gist of the claims.

  In the above description, the case where the present invention is applied to a tandem type color printer is shown. However, the present invention can be applied to a color printer other than a tandem type printer, and can also be applied to a monochrome printer.

DESCRIPTION OF SYMBOLS 1 Printer main body 2 Image forming unit 2-1 Frame 2a Photoconductor unit 2a-1 Case 8 Photoconductor drum 8a Base body 8b Photosensitive layer 21 Photostatic device 21b Light guide means 21b-1 First light guide member 21b-2 First 2 light guide member 21c case 21c-a inner peripheral surface 21c-b end wall 21c-c holding projection 21c-1 first opening 21c-2 second opening F film G space R1 outer diameter R2 outer diameter

Claims (14)

A light source disposed on the side of an image carrier on which an electrostatic latent image is formed;
A light guide means arranged to face the image carrier along the longitudinal direction of the image carrier, and guiding light emitted from the light source to the surface of the image carrier;
The light guiding means includes
A first light guide member, and a second light guide member disposed between the light source and the first light guide member,
An optical static eliminator characterized by that. At least one of the first light guide member and the second light guide member, and the light guide means have a length corresponding to the width of a recording medium having a fixed size.
The light static eliminator according to claim 1. At least one of the first light guide member and the second light guide member has a cylindrical shape or a columnar shape extending in the longitudinal direction of the image holding body.
The optical static eliminating device according to claim 1 or 2, characterized in that. A case having a first opening that covers the light guide and that opens toward the image carrier and a second opening that opens toward the light source;
The optical static elimination device according to any one of claims 1 to 3.   The said case is formed with white resin, The optical static elimination apparatus in any one of Claims 1-4 characterized by the above-mentioned. A holding projection for holding the light guide means on the case is formed at an edge of the first opening of the case.
6. The light static eliminator according to claim 4 or 5. The second light guide member has a shape in which a cross-sectional area decreases as the distance from the light source increases.
An optical static elimination device according to any one of claims 1 to 6. A portion of the second light guide member overlaps the first light guide member in the longitudinal direction of the image carrier,
The optical static elimination apparatus according to any one of claims 1 to 7. The boundary portion of the outer peripheral surface of the first light guide member and the second light guide member has a non-step shape.
The optical static elimination apparatus according to any one of claims 1 to 8. At the boundary portion between the first light guide member and the second light guide member, the outer diameter of the second light guide member is smaller than the outer diameter of the first light guide member. Yes,
The optical static elimination apparatus according to any one of claims 1 to 8. The first light guide member and the second light guide member are spaced apart from each other,
The optical static elimination apparatus according to any one of claims 1 to 7. A light amount reducing member for reducing the amount of light guided to the image carrier is provided at a boundary portion between the first light guide member and the second light guide member.
The optical static elimination apparatus according to any one of claims 1 to 7. The light amount reducing member is a light-transmitting film or a holding protrusion that is formed at an edge of the first opening of the case and holds the light guide means in the case.
The optical static elimination apparatus of Claim 12 characterized by the above-mentioned. An optical static elimination device according to any one of claims 1 to 13,
An image forming unit that is disposed opposite to the light guiding unit of the light static eliminator and includes an image carrier that forms an electrostatic latent image on a surface thereof, and is detachably provided on the apparatus main body,
At least one of the first light guide member and the second light guide member is attached to the image forming unit;
An image forming apparatus.

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