JP2008268273A - Optical discharging device, image holder unit, image forming unit, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical discharging device which is capable of guiding light from a light source to a surface of a photoreceptor drum without a lack and without using light guiding members. <P>SOLUTION: The optical discharging device for discharging the surface of the photoreceptor drum on which an electrostatic latent image is formed, by irradiation with light includes: a LED 21a which is disposed sideways in a rotating shaft direction of the photoreceptor drum and emits light in the rotating shaft direction of the photoreceptor drum; and a reflecting member 21b which is disposed in the rotating shaft direction of the photoreceptor drum and reflects light from the LED 21a by a reflecting surface 21b-1 facing the photoreceptor drum to guide the light to the surface of the photoreceptor drum. The reflecting surface 21b-1 of the reflecting member 21b is bent concavely to the photoreceptor drum. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photostatic discharge device, an image carrier unit, an image forming unit, 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, whereby 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.

  The light neutralizing device has a rod-shaped light guide member. The light guide member is disposed to face the photosensitive drum at a predetermined distance along the axial direction of the photosensitive drum so that the axes thereof are parallel to each other. The light guide member is made of a material having excellent translucency, for example, a resin such as acrylic, polycarbonate, polystyrene, or glass.

  A surface of the light guide member facing the photosensitive drum is provided with a lens portion in which grooves extending in the width direction are continuously formed in the longitudinal direction.

  This groove has a certain apex angle, reflects a part of the light from the light source incident from one end in the longitudinal direction of the light guide member toward the photosensitive drum, and reflects the light on the surface of the photosensitive drum. Irradiate uniformly. The grooves are formed such that the pitch gradually increases and the depth increases as the distance from the light source increases. Accordingly, the light passing through the light guide member in the longitudinal direction gradually decreases in light quantity, but since the groove pitch of the lens part is large and the depth is deep, the ratio of the light quantity output to the photosensitive drum is As a result, the amount of light output to the photosensitive drum becomes substantially constant in the axial direction of the photosensitive drum.

  In addition, as a technique regarding an optical static elimination apparatus, what was described in Unexamined-Japanese-Patent No. 2005-275130, Unexamined-Japanese-Patent No. 2006-113216, Unexamined-Japanese-Patent No. 2701367, Unexamined-Japanese-Patent No. 2006-276529 etc. is known, for example. Yes.

  Here, in the conventional light static elimination apparatus, one bar-shaped light guide member is provided for one light source. Therefore, in the case of a color image forming apparatus having a plurality of photosensitive drums, the same number of light guiding members as the number of photosensitive drums are required, which increases the cost.

  In addition, it is conceivable to directly irradiate the photosensitive drum with a light source without using an expensive light guide member. However, in an image forming apparatus with a high printing speed, the peripheral speed of the photosensitive drum is increased, so that the photosensitive drum is moved away from the light source. As the amount of light decreases, the residual charge on the photosensitive drum is not sufficiently removed. Then, image quality defects such as density unevenness (density unevenness in which the density increases on the side opposite to the light source of the photosensitive drum) and positive ghost (positive ghost appears on the side opposite to the light source of the photosensitive drum) are likely to occur.

Increasing the amount of light from the light source increases the static elimination performance of the portion of the semiconductor drum that is far from the light source, but this time, the image quality is poor (density unevenness) due to the shortening of the light source life and light fatigue of the photosensitive drum.
JP-A-2005-275130 JP 2006-113216 A Japanese Patent No. 2701367 JP 2006-276529 A

  The present invention has been made from the above-described technical background, and provides a technique related to an optical static elimination device that can guide light from a light source to a surface of an image holding member without using a light guide member. For the purpose.

  In order to solve the above-mentioned problems, the optical static eliminator of the present invention according to claim 1 is an optical static eliminator that neutralizes the surface of an image carrier on which an electrostatic latent image is formed by light irradiation, wherein the image holding A light source that illuminates light in the direction of the rotation axis of the image carrier and a reflecting surface that is arranged in the direction of the axis of rotation of the image carrier and faces the image carrier And a reflecting member that reflects the light from the light source and guides the light to the surface of the image holding member.

  According to a second aspect of the present invention, in the first aspect of the present invention, the reflecting member has a shape in which the reflecting surface is concavely curved toward the image holding member.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the reflecting member is characterized in that the reflecting surface is white.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the reflecting member is characterized in that the reflecting surface is mirror-finished.

  The invention according to claim 5 is the invention according to claim 1 or 2, wherein at least the reflecting surface of the reflecting member is a metal.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the reflecting member is at least one of an interval between the reflecting surface and the image holding body and a width of the reflecting surface. Is changed according to the distance from the light source.

  The invention described in claim 7 is the invention described in claim 1 or 2, characterized in that the reflection surface of the reflection member has different reflection characteristics on the light source side and on the opposite side.

  The invention described in claim 8 is characterized in that, in the invention described in claim 7, the reflection member is formed such that at least one hole is formed in the reflection surface on the light source side.

  The invention according to claim 9 is the invention according to claim 7, wherein the reflection surface of the reflection member has a surface roughness that decreases from the light source side toward the opposite side. .

  The invention described in claim 10 is the invention described in claim 7, characterized in that the reflection surface of the reflection member is a metal on the opposite side of the light source.

  According to an eleventh aspect of the present invention, in the invention according to the seventh aspect, the reflective surface of the reflective member has higher whiteness from the light source side toward the opposite side.

  In order to solve the above-described problem, an image carrier unit according to a twelfth aspect of the present invention includes a housing including a reflective member that constitutes the light static eliminator according to any of the first to eleventh aspects, and the reflection An image holding member that is rotatably attached to the casing so as to face the reflecting surface of the member and forms an electrostatic latent image on the surface thereof, and the reflecting member is formed integrally with the casing. It is characterized by that.

  In order to solve the above-described problem, an image forming unit according to a thirteenth aspect of the present invention includes a frame including a reflective member that constitutes the light neutralizing device according to any of the first to eleventh aspects, and a detachable attachment to the frame. An image carrier unit that is mounted so as to be rotatable and is rotatably attached to the reflective surface of the reflective member so that an electrostatic latent image is formed on the surface. It is formed integrally with the frame.

  In order to solve the above-described problems, an image forming apparatus according to a fourteenth aspect of the present invention is the photostatic discharge device according to any one of the first to eleventh aspects, the image carrier unit according to the twelfth aspect, or the thirteenth aspect. The image forming unit is mounted.

  According to the first aspect of the present invention, it is possible to guide the light from the light source to the surface of the image holding member without any shortage from the light source regardless of the distance without using the light guide member.

  According to the second aspect of the present invention, the light is focused on the image holding member by the reflecting surface curved in a concave shape as compared with the case where the present invention is not adopted. It can be led to the surface, and the static elimination performance is improved.

  According to the invention described in claim 3, since the light from the light source is not absorbed by the reflecting surface as compared with the case where the present invention is not adopted, the light from the light source can be efficiently guided to the surface of the image carrier, The static elimination performance is improved.

  According to the invention described in claim 4, since the reflection efficiency on the reflecting surface is improved as compared with the case where the present invention is not adopted, the light of the light source can be efficiently guided to the surface of the image carrier, and the charge eliminating performance is improved. improves.

  According to the invention described in claim 5, since the reflection efficiency on the reflection surface is improved as compared with the case where the present invention is not adopted, the light from the light source can be efficiently guided to the surface of the image holding member, and the charge removal performance. Will improve.

  According to the sixth aspect of the present invention, compared with the case where the present invention is not adopted, the light quantity distribution of the irradiation light in the direction of the rotation axis of the image carrier is further leveled. On the other hand, the charge can be removed uniformly.

  According to the seventh aspect of the present invention, compared with the case where the present invention is not adopted, the light quantity distribution of the irradiation light in the direction of the rotation axis of the image carrier is further leveled. On the other hand, the charge can be removed uniformly.

  According to the eighth aspect of the present invention, compared with the case where the present invention is not adopted, the light quantity distribution of the irradiation light in the rotation axis direction of the image holding body is further leveled, so that the image holding body is moved in the axial direction. On the other hand, the charge can be removed uniformly.

  According to the ninth aspect of the present invention, compared to the case where the present invention is not adopted, the light quantity distribution of the irradiation light in the direction of the rotation axis of the image carrier is further leveled. On the other hand, the charge can be removed uniformly.

  According to the tenth aspect of the present invention, compared to the case where the present invention is not adopted, the light quantity distribution of the irradiation light in the rotation axis direction of the image holding body is further leveled, so that the image holding body is moved in the axial direction. On the other hand, the charge can be removed uniformly.

  According to the eleventh aspect of the invention, compared to the case where the present invention is not adopted, the light quantity distribution of the irradiation light in the direction of the rotation axis of the image carrier is further leveled. On the other hand, the charge can be removed uniformly.

  According to the twelfth aspect of the invention, as compared with the case where the present invention is not adopted, the trouble of attaching the reflecting member can be saved, and therefore the number of assembling steps of the image carrier unit can be reduced.

  According to the thirteenth aspect of the present invention, as compared with the case where the present invention is not adopted, the trouble of attaching the reflecting member can be saved, so that the number of assembling steps of the image forming unit can be reduced.

  According to the fourteenth aspect of the present invention, the light from the light source can be guided to the surface of the image carrier by the reflecting member without using the light guide member and without using the light guide member, as compared with the case where the present invention is not adopted. Therefore, the cost of the image forming apparatus can be reduced.

  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 the vertical direction in a substantially central portion of a tandem type color printer main body 1. Further, inside the color printer main body 1, a transfer material onto 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 figure) of the image forming unit 2. A sheet conveying belt unit 3 that conveys the sheet in a state is disposed, and a control unit 4 including a control circuit or the like is provided on the other side of the image forming unit 2 (on the right side in the drawing). Power supply circuit units 5 each including a high voltage power supply circuit and the like are disposed obliquely above.

  In addition, a paper feed cassette 6 that houses and feeds paper 18 or the like as a transfer material 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 the corresponding color toner, and a static eliminating device 21 (21Y, 21M, 21C) that removes charge remaining on the photosensitive drum 8 after development. , 21K) and on the photosensitive drum 8 Cleaning cleans the residual untransferred toner unit 12 (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 static eliminator 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.

  Here, in the photosensitive drum 8 of the present embodiment, the diameter φ is 24 mm, and attenuation when charged with 400 V (attenuation when the charged photosensitive drum is left in a dark room) is room temperature 28 ° C. and humidity 85%. 15.9 V after 0.31 sec (charging potential: 400 V-15.9 V = 384.1 V), 15.6 V after 0.31 sec at room temperature 10 ° C. and 15% (charging potential: 400 V-15.6 V = 384.4 V) ). Therefore, if the attenuation rate is a minute time of about 0.3 sec, it has a linearity that attenuates about 5 V in 0.1 sec. The process speed (linear speed of the photosensitive drum) is about 78.7 mm / sec for color printing and about 105 mm / sec for monochrome printing. Since the peripheral length of the photosensitive drum is 75.36 mm (24 mm (photosensitive drum diameter) × 3.14 (circumferential ratio)), in color printing, the photosensitive drum 8 rotates approximately once per second. It becomes speed.

  In the present invention, the specification of the photosensitive drum is not limited to the above numerical values, and it is needless to say that various specifications can be selected.

  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 LB 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, as shown in FIG. 1, the sheet conveying belt unit 3 includes a sheet conveying belt 17 that circulates and moves as an endless belt, and the sheet conveying belt 17 includes the image forming units 7Y, 7M, and 7C. , Transported in a state of electrostatically adsorbing paper 18 as a transfer material onto which toner images of each color of yellow (Y), magenta (M), cyan (C), and black (K) formed at 7K are transferred. Is configured to do.

  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 (recording medium take-out means) 35 that nips the uppermost paper 18 is disposed immediately above the paper 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 the transfer material, for example, various sizes such as A4 size, A3 size, B5 size, and B4 size, and various materials such as thick paper such as plain paper and coated paper, and an OHP sheet are 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 by the discharge roll 32 with the print surface facing down onto the discharge tray 33 provided on the upper portion of the color printer main body 1, and the printing operation is completed. .

  Note that a color printer can print an image of a desired color such as monochrome as well as a color image, and yellow (Y), magenta (M), magenta (M), and the like depending on 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 static eliminator 21 of the image forming apparatus according to the present embodiment is an optical static eliminator that optically removes residual charges on the photosensitive drum 8 by light irradiation. As shown in FIG. 2, a cylinder made of aluminum. A photosensitive layer 8b made of a photo-semiconductor such as OPC (Organic Photo Conductor) is provided on the entire outer periphery of the substrate 8a. It has LED (light source) 21a which irradiates light toward the rotating shaft direction of the body drum 8.

  Further, the static eliminator 21 has a long reflecting member 21b made of, for example, a plastic such as ABS resin or a metal such as stainless steel or aluminum along the rotation axis direction of the photosensitive drum 8. The photosensitive drum 8 is arranged at a predetermined interval (for example, 8 mm).

  Here, the LED 21a which is a light source is manufactured by, for example, mounting an LED chip on a metal lead and sealing the portion with a transparent resin, and on the one end side in the longitudinal direction of the reflecting member 21b. Has been placed. The LED 21a uses a wavelength that matches the photosensitivity of the photosensitive layer 8b of the photosensitive drum 8.

  As shown in FIG. 3, the reflecting member 21 b is arranged so that the reflecting surface 21 b-1, which is the inner peripheral surface, is curved in a concave shape, and the reflecting surface 21 b-1 is directed to the photosensitive drum 8. . At one end (right side in the figure) of the reflecting member 21b, the reflecting surface 21b-1 opens outward. And LED21a mentioned above is arrange | positioned at this opened one end side so that the reflective surface 21b-1 may be faced, and irradiates the said reflective surface 21b-1. Further, a side wall portion 21b-2 that is substantially perpendicular to the reflecting surface 21b-1 is formed at the other end (left side in the case of illustration) of the reflecting member 21b. Note that the reflecting surface may not be curved, and may be a flat surface, for example.

  As shown in FIG. 4, on the outer surface 21b-3 opposite to the reflecting surface 21b-1, protrusions 21b-3a are formed at both ends in the longitudinal direction, and engaging claws 21b-3b are formed at the center. ing. Then, the protrusion 21b-3a is fitted into the fitting hole formed in the housing 2a-1 (FIG. 5) of the photosensitive unit (image holding unit) 2a described later, and the engaging claw 21b-3b is fitted into the engaging groove. The engaging member 21b is attached to the housing 2a-1.

  In the present embodiment, the photoreceptor unit is detachably attached to the frame of the image forming unit 2, and the reflection member 21b is thus attached to the photoreceptor unit. On the other hand, the LED 21a is arranged not on the photosensitive unit but on the frame of the image forming unit 2. However, it goes without saying that the LED 21a may also be arranged in the photosensitive unit.

  In the static eliminator 21 having the above configuration, when light is irradiated from the LED 21a toward the rotation axis of the photosensitive drum 8, a part directly reaches the surface of the photosensitive drum 8, and the other part is reflected. It reaches the reflecting surface 21b-1 of the member 21b. As described above, since the reflecting surface 21b-1 faces the photosensitive drum 8, the light that has reached the reflecting surface 21b-1 is reflected by the reflecting surface 21b-1 to the surface of the photosensitive drum 8. It is guided. Further, another part of the light emitted from the LED 21a reaches the inner wall 21b-2a of the side wall 21b-2, is reflected here, and is similarly guided to the surface of the photosensitive drum 8.

  Then, the charges remaining on the photosensitive drum 8 after the toner image transfer are removed by the light reaching the surface of the photosensitive drum 8 directly or reflected by the reflecting surface 21b-1 or the inner wall 21b-2a. The 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.

  Thus, in the static elimination apparatus 21 of this Embodiment, the light from LED21a is reflected by the reflective surface 21b-1 of the reflective member 21b, and is guide | induced to the surface of the photosensitive drum 8. FIG. Therefore, even if an expensive light guide member is not used, the light from the LED 21a can be guided to the surface of the photosensitive drum 8 from the LED 21a regardless of the distance by the reflecting member 21b. A light neutralizing device that does not cause any problems can be obtained.

  Further, since the light guide member is unnecessary, the apparatus can be reduced in size.

  Further, since the reflecting surface 21b-1 of the reflecting member 21b is concavely curved toward the photosensitive drum 8, the light is focused on the photosensitive drum 8 by the reflecting surface 21b-1. Therefore, the light from the LED 21a can be efficiently guided to the surface of the photosensitive drum 8, and the charge removal performance is improved.

  In FIG. 5, 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 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, the charging roll 9, the developing device 11, and the static eliminating device 21 (this embodiment). In the case of this form, the reflection member 21b), the cleaning device 12, and the toner cartridge 13 constituting the static elimination device 21 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.

  In FIG. 5, 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 such a photoreceptor unit 2a, the reflecting member 21b is attached to the housing 2a-1 by the projections 21b-3a and the engaging claws 21b-3b formed on the reflecting member 21b as described above.

  However, not only when the reflecting member 21b and the housing 2a-1 are made of the same material, but also when the reflecting member 21b and the housing 2a-1 are made of different materials as in the present embodiment, The reflection member 21b and the housing 2a-1 can be integrally formed by using a known technique for integrally molding different materials. In this way, the trouble of attaching the reflecting member 21b to the housing 2a-1 can be saved, so that the number of assembling steps of the photosensitive unit 2a can be reduced.

  In FIG. 6, the image forming unit 2 has a frame 2-1. Then, four photoconductor units 2a (FIG. 5) provided corresponding to the development colors are detachably mounted on the frame 2-1.

  Here, the reflecting member 21b may be integrally formed with the frame 2-1 of the image forming unit 2 instead of the housing 2a-1 of the photoreceptor unit 2a. In this way, the trouble of attaching the reflecting member 21b to the housing 2a-1 or the frame 2-1 can be saved, and therefore the number of assembling steps of the image forming unit 2 can be reduced.

  Then, an expensive light guide member is used by mounting the static eliminator 21 described above on the printer main body 1 or by mounting the photoconductor unit 2 a or the image forming unit 2 described above on the printer main body 1. Therefore, the light from the LED 21a can be guided to the surface of the photosensitive drum 8 without any shortage by the reflecting member 21b, so that the cost of the image forming apparatus itself can be reduced.

  In the above description, the reflection surface 21b-1 of the reflection member 21b constituting the static elimination device 21 is a curved surface or a flat surface, but such a reflection surface 21b-1 can be white. If white, the light from the LED 21a is not absorbed by the reflecting surface 21b-1, so that the light from the LED 21a can be efficiently guided to the surface of the photosensitive drum 8, and the charge removal performance is improved.

  Further, the reflecting surface 21b-1 of the reflecting member 21b can be mirror-finished to Ra (surface roughness) = 1.0 μm, for example. If the mirror finish is used, the light reflection efficiency at the reflection surface 21b-1 is improved. Similarly, the light from the LED 21a can be efficiently guided to the surface of the photosensitive drum 8, and the charge removal performance is improved. In addition, the numerical value of the said surface roughness is an example, and this invention is not limited to this value.

  Furthermore, the reflecting surface 21b-1 of the reflecting member 21b may be a metal. Even if it does in this way, since the reflection efficiency of the light in the reflective surface 21b-1 improves, the light of LED21a can be efficiently guide | induced to the surface of the photosensitive drum 8 similarly, and static elimination performance improves. In this case, the reflecting surface 21b-1 may be made of metal by making the reflecting member 21b itself metal. That is, at least the reflection surface 21b-1 may be a metal.

  In addition, there exists sticking of a metal film film as an example of the means which uses the reflecting surface 21b-1 of the reflecting member 21b as a metal. That is, for example, aluminum, chromium, nickel, gold or the like is vapor-deposited on the surface of a polycarbonate film to form a metal thin film to produce a metal film, which can be attached to the reflecting surface 21b-1. .

  Here, the reflecting member 21b is configured such that the interval between the reflecting surface 21b-1 and the photosensitive drum 8 changes according to the distance from the LED 21a, or the width of the reflecting surface 21b-1 according to the distance from the LED 21a. Can be configured to change.

  That is, as shown in FIG. 7, the reflecting member 21b is arranged so that the distance between the reflecting surface 21b-1 and the photosensitive drum 8 gradually becomes narrower from the side where the LED 21a is arranged toward the opposite side. Yes (H1> H2). Further, as shown in FIG. 8, the reflecting member 21b is formed so that the width of the reflecting surface 21b-1 gradually increases from the side where the LED 21a is disposed (right side in the case of illustration) toward the opposite side. (W1 <W2).

  In the former case, the reflecting surface 21b-1 approaches the photosensitive drum 8 as the distance from the LED 21a increases. In the latter case, the amount of reflected light increases as the distance from the LED 21a increases. In addition, the light quantity distribution of the irradiation light in the direction of the rotation axis of the photosensitive drum 8 is further leveled. Therefore, the photosensitive drum 8 can be uniformly discharged in the axial direction, and an image having no print density difference or ghost difference in the axial direction of the photosensitive drum 8 can be obtained.

  The technique for changing the interval between the reflecting members 21b and the technique for changing the width of the reflecting member 21b can be used in combination.

  As another means for leveling the light quantity distribution of the irradiation light in the rotation axis direction of the photosensitive drum 8, the reflection surface 21b-1 of the reflection member 21b is reflected on the LED 21a side and the opposite side. May be different.

  As a first specific example, as shown in FIG. 9, a hole 21b-1a opened in the reflecting surface 21b-1 is formed in the reflecting member 21b. As shown in the drawing, a plurality of holes 21b-1a are formed so as to gradually become smaller from the LED 21a side toward the opposite side. In this configuration, on the LED 21a side of the reflecting surface 21b-1 where the amount of light is relatively large, light leaks from the hole 21b-1a and the amount of reflected light decreases. As a result, irradiation in the rotation axis direction of the photosensitive drum 8 occurs. The light intensity distribution is leveled. It should be noted that the size of the holes may be the same, and the amount of reflected light may be adjusted by the hole interval. The number of holes 21b-1a may be any number, but in the case of one, it is formed on the LED 21a side.

  As a second specific example, as shown in FIG. 10, the surface roughness of the reflecting surface 21 b-1 of the reflecting member 21 b decreases from the LED 21 a side toward the opposite side. In this configuration, the amount of light that diffusely increases and the amount of light that reaches the photosensitive drum 8 decreases as the reflection surface 21b-1 on the reflective surface 21b-1 becomes relatively larger, and the amount of light that reaches the photosensitive drum 8 decreases. The light quantity distribution of the irradiation light in the direction is leveled.

  As a 3rd specific example, as shown in FIG. 11, about the reflective surface 21b-1 of the reflective member 21b, the opposite side of LED21a is made into the metal surface 21b-1b. In this configuration, the amount of reflected light increases on the side opposite to the LED 21a of the reflecting surface 21b-1 where the amount of light becomes relatively small, so the light amount distribution of the irradiated light in the direction of the rotation axis of the photosensitive drum 8 is leveled. In addition, the metal surface 21b-1b is produced by sticking the metal film film mentioned above, for example.

  As a fourth specific example, the reflecting surface 21b-1 of the reflecting member 21b is configured so that the whiteness increases from the LED 21a side toward the opposite side. In this configuration, since the light is hardly absorbed on the side opposite to the LED 21a of the reflecting surface 21b-1 where the light amount becomes relatively small and the reflected light amount increases, the light amount distribution of the irradiation light in the rotation axis direction of the photosensitive drum 8 is increased. Is leveled.

  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.

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 illustrating a static eliminator mounted on the image forming apparatus in FIG. 1 in relation to a photosensitive drum. It is a perspective view which shows the static elimination apparatus which concerns on this invention from the reflective surface side. It is a perspective view which shows the static elimination apparatus which concerns on this invention from the outer surface side. It is a perspective view showing a photoconductor unit to which a static eliminator according to the present invention is mounted. FIG. 3 is a perspective view showing an image forming unit to which a photoconductor unit according to the present invention is mounted. It is explanatory drawing which shows the modification of the static elimination apparatus which concerns on this invention. It is a perspective view which shows the reflection member in the other modification of the static elimination apparatus which concerns on this invention. It is a perspective view which shows the reflection member in the other modification of the static elimination apparatus which concerns on this invention. It is a perspective view which shows the reflection member in the other modification of the static elimination apparatus which concerns on this invention. It is a perspective view which shows the reflection member in the other modification of the static elimination apparatus which concerns on this invention.

Explanation of symbols

1 Color printer body (image forming device)
2 Image forming unit 2-1 Frame 2a Photosensitive unit (image holding unit)
2a-1 Case 8 Photosensitive drum (image carrier)
8a Substrate 8b Photosensitive layer 21 Static elimination device (photo static elimination device)
21a LED (light source)
21b Reflective member 21b-1 Reflective surface 21b-1a Hole 21b-1b Metal surface 21b-2 Side wall 21b-2a Inner wall 21b-3 Outer surface 21b-3a Protrusion 21b-3b Engagement claw

Claims (14)

An optical static elimination device that neutralizes the surface of an image carrier on which an electrostatic latent image is formed by light irradiation,
A light source disposed on the side of the rotation axis direction of the image carrier and irradiating light in the rotation axis direction of the image carrier;
A reflecting member that is disposed in the direction of the rotation axis of the image carrier, reflects light from the light source at a reflecting surface facing the image carrier, and guides the light to the surface of the image carrier;
An optical static eliminator characterized by comprising:   The optical static elimination device according to claim 1, wherein the reflecting member has a shape in which the reflecting surface is concavely curved toward the image holding member.   The optical static elimination device according to claim 1, wherein the reflective member has a white reflective surface.   3. The light neutralizing device according to claim 1, wherein the reflecting member has a mirror-finished reflecting surface.   The optical static elimination device according to claim 1, wherein at least the reflection surface of the reflection member is a metal.   6. The reflecting member according to claim 1, wherein at least one of an interval between the reflecting surface and the image holding body and a width of the reflecting surface is changed according to a distance from the light source. The light static elimination apparatus in any one of.   3. The light neutralizing apparatus according to claim 1, wherein the reflection surface of the reflection member has different reflection characteristics on the light source side and on the opposite side.   8. The light neutralizing device according to claim 7, wherein the reflecting member is formed with at least one hole opened on the reflecting surface on the light source side.   8. The light static eliminator according to claim 7, wherein the reflection surface of the reflection member has a surface roughness that decreases from the light source side toward the opposite side.   8. The light neutralizing apparatus according to claim 7, wherein the reflection surface of the reflection member is made of metal on the opposite side of the light source.   8. The light neutralizing device according to claim 7, wherein the reflective surface of the reflective member has higher whiteness from the light source side toward the opposite side. A housing provided with a reflecting member that constitutes the light static eliminator according to any one of claims 1 to 11,
An image holding member that is rotatably attached to the housing so as to face the reflecting surface of the reflecting member, and on which an electrostatic latent image is formed;
The reflective member is formed integrally with the housing.
An image carrier unit characterized by that. A frame provided with a reflecting member that constitutes the light static eliminator according to any one of claims 1 to 11,
An image carrier unit including an image carrier that is detachably attached to the frame, is rotatably attached to the reflective surface of the reflective member, and has an electrostatic latent image formed on the surface thereof;
The reflecting member is integrally formed with the frame.
An image forming unit.   An image forming apparatus, comprising: the photostatic discharge device according to claim 1; the image carrier unit according to claim 12; or the image forming unit according to claim 13.

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