JP4656877B2 - Static eliminator - Google Patents

Description

  The present invention relates to a static eliminator for removing residual charges on a photoconductor mounted on an image forming machine such as a digital copying machine, a laser printer, and a laser facsimile, and an image forming machine equipped with the static eliminator. In particular, the present invention relates to measures for enabling a compact design of an image forming machine.

  Conventionally, as an image forming (copying) operation in an electrophotographic image forming machine typified by a digital copying machine, first, an original image is read by a scanner unit and statically placed on a photosensitive drum based on the original image data. An electrostatic latent image is formed. Then, toner is attached to the electrostatic latent image, and the image data is visualized on the photosensitive drum. Thereafter, the recording paper conveyed through the paper conveyance path is passed between the photosensitive drum and the transfer roller, and the toner image on the photosensitive drum is transferred to the surface of the recording paper. Then, the recording paper is passed through a fixing roller, and the toner image is fixed on the recording paper by heating and pressurization with the fixing roller. The recording paper on which image formation has been performed in this manner is then discharged onto a paper discharge tray via a paper discharge path. Further, the toner remaining on the surface of the photosensitive drum is removed and collected by a cleaning unit having a cleaning blade. Further, the residual charge on the photosensitive drum is removed by a static eliminator equipped with a static eliminator lamp and a static eliminator.

  On the other hand, in the case of an electrophotographic printer, an electrostatic latent image is formed on the photosensitive drum based on image data received from a connected terminal device (such as a personal computer). The image forming operation after the electrostatic latent image is formed is the same as that of the digital copying machine described above.

  By the way, in recent years, there is an increasing demand for downsizing of this type of image forming machine, and as one means for realizing this, it is mentioned to reduce the diameter of the photosensitive drum. Around the photosensitive drum, a charger, a developing device, a transfer device, a cleaning unit, a static eliminator, and the like are arranged in order in the circumferential direction. However, when the diameter of the photosensitive drum is reduced, the circumferential length of the drum is shortened. It becomes difficult to arrange these devices side by side in the circumferential direction. Therefore, there is a limit to reducing the diameter of the photosensitive drum.

Japanese Patent Application Laid-Open No. 2004-228561 discloses a configuration in which the charge-removing light from the charge-removing lamp is allowed to pass through the inside of the charger case and can be irradiated to the photosensitive drum. In other words, the charging area by the charger and the irradiation area of the static elimination lamp are overlapped to reduce the installation space for the charger and the static elimination device, thereby reducing the size of the image forming machine.
JP-A-8-16053

  However, in the configuration disclosed in Patent Document 1, if the charge removal light from the charge removal lamp is applied during the charging operation by the charger, the charge removal area on the photosensitive drum is irradiated with the charge removal light. As a result, the electric potential of the surface of the photosensitive drum is not uniform, and the surface of the photosensitive drum cannot be charged, which hinders the image forming operation. For this reason, the one disclosed in Patent Document 1 is provided with a shutter for switching the optical path of the static elimination light, and the residual due to the static elimination light irradiation from the static elimination lamp while performing the switching operation of the shutter. The charge discharging operation and the charging operation by the charger are performed. However, this increases the manufacturing cost and complicates the control operation.

  In the configuration disclosed in Patent Document 1, the shutter is rotated to the retracted position to perform the charge removal operation, and then the shutter is rotated to the shielding position to form one image. An electrostatic latent image (electrostatic latent image of the entire image) is formed on the surface of the photosensitive drum. For this reason, when the peripheral length of the outer surface of the photosensitive drum is longer than the length in the conveyance direction of the recording paper, the image forming operation can be performed, but when the peripheral length of the outer surface of the photosensitive drum is shorter than the length in the conveyance direction of the recording paper. However, the image forming operation cannot be performed satisfactorily. That is, it is necessary to set the circumference of the outer surface of the photosensitive drum to be longer than the length of the maximum size recording paper among the usable recording papers. In this way, setting the peripheral length of the outer surface of the photosensitive drum to be long becomes a great obstacle to reducing the diameter of the photosensitive drum.

  It is also conceivable to reduce the diameter of the photosensitive drum by eliminating the static eliminator. However, in this case, the charging operation by the charger must be performed at a high potential that is not affected by the residual charge, and the surface of the photosensitive drum is deteriorated, making it difficult to extend its life.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a static eliminator capable of performing a good image forming operation while reducing the diameter of the photosensitive drum, and the static eliminator. Another object is to provide an image forming machine.

-Summary of invention-
In order to achieve the above object, the solution means of the present invention uses the outer surface of the casing of the charger (charging means) to reflect the discharge light (discharge light for discharge) toward the surface of the photoreceptor. This eliminates the need for disposing a static eliminating device concentrically with the charger and the cleaning unit, and makes it possible to reduce the distance between the charger and the cleaning unit, thereby reducing the diameter of the photosensitive drum. ing.

-Solution-
Specifically, the present invention is arranged at a position close to a charging means for charging the surface of the photosensitive member, and emits a neutralizing irradiation light for removing the residual charge on the surface of the photosensitive member after the image forming operation. A static eliminator provided with static eliminator is assumed. With respect to this static eliminator, it is configured to irradiate the surface of the photosensitive member by irradiating the neutralizing irradiation light emitted from the neutralizing means toward the outer surface of the casing of the charging means and reflecting the neutralizing irradiation light on the outer surface of the casing. .

  In this case, a cleaning unit for removing toner remaining on the surface of the photoconductor after the image forming operation is disposed around the photoconductor, and the charge removing unit is disposed on the back side of the cleaning unit on the side opposite to the photoconductor. It is arranged.

  In the past, the cleaning unit, the charge eliminating unit, and the charging unit are arranged on a concentric circle around the photosensitive member rotation center from the upstream side to the downstream side in the movement direction (rotation direction) of the photosensitive member. It was. On the other hand, in the present solution means, it is sufficient that only the optical path of the neutralizing irradiation light exists between the cleaning unit and the charging means without providing the neutralizing means between them. Or, as will be described later, in the case where a part of the cleaning unit (the following opening) is configured to allow the neutralizing irradiation light to pass, there is almost no gap between the cleaning unit and the charging means. For this reason, the interval between the cleaning unit and the charging unit can be significantly reduced, and the diameter of the photosensitive drum can be reduced. In addition, since the light path of the neutralizing irradiation light reflected from the outer surface of the casing of the charging means is changed in the direction away from the charging area on the photosensitive member by the charging means, the neutralizing irradiation light enters the charging area. To stabilize the charging characteristics by avoiding the situation that the surface potential of the photosensitive member varies due to irradiation (so-called stray light or leakage light occurs) or the surface of the photosensitive member cannot be charged. You can also.

  As a more effective configuration for disposing the charge eliminating unit on the back side of the cleaning unit, the following can be mentioned. In other words, an opening is formed in the casing member of the cleaning unit (for example, a mounting plate for attaching the cleaning blade), and the discharging means passes through the opening of the casing member and is directed toward the casing outer surface of the charging means. It is set as the structure which irradiates light. In this case, if the opening of the casing member is formed in a slit shape so that the irradiation area of the discharging light from the discharging means is a specific (minimum necessary) area, the stray light and leakage light can be surely prevented. Can do.

  The casing outer surface of the charging means that receives the above-mentioned discharge light for neutralization may be mirror-finished or may have a satin finish made up of minute irregularities. In other words, among these outer surfaces of the casing of the charging unit, these treatments are performed only on the outer surface that receives the neutralizing irradiation light emitted from the neutralizing unit (the outer surface that reflects the neutralizing light toward the photoconductor). When the mirror finish is applied, it is possible to irradiate the surface of the photosensitive member with almost no reduction in the amount of the light for discharging from the discharging means, and it is possible to reliably remove the residual charges. In addition, when the satin finish is applied, the neutralizing irradiation light reflected on the outer surface of the casing of the charging means can be obtained as scattered light directed to the photoconductor, and a uniform amount of neutralization can be obtained over a wide range of the photoconductor surface. Irradiation light can be irradiated. For this reason, it is possible to avoid the occurrence of uneven charge removal on the surface of the photoreceptor.

  Note that an image forming machine including the static eliminator described in any one of the above-described solutions is also within the scope of the technical idea of the present invention. That is, after removing the residual charge on the surface of the photoconductor by the neutralizing irradiation light emitted from the static eliminator of the static eliminator, the surface of the photoconductor is charged by the charging means, and then forming an electrostatic latent image on the surface of the photoconductor The image forming machine is configured to execute an image forming operation by sequentially forming a visible image with an image visible agent and transferring the visible image to a recording medium.

  In the present invention, by eliminating the irradiation light for static elimination toward the surface of the photoreceptor using the outer surface of the casing of the charging means, it is not necessary to dispose the static elimination device concentrically with the charger and the cleaning unit, It is possible to reduce the interval between the charger and the cleaning unit. For this reason, it is possible to simultaneously perform the charge removal operation of the residual charge by the irradiation of the discharge light from the charge removal means and the charging operation by the charger, while reducing the size of the image forming machine by reducing the diameter of the photoconductor. Can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a case where the present invention is applied to a color printer will be described.

  FIG. 1 schematically shows the internal configuration of an image forming machine according to the present embodiment. The image forming machine is configured to output a multicolor (full color) image or a single color (monochrome) on a predetermined sheet (recording medium such as a recording sheet) in accordance with image data transmitted from the outside (for example, a terminal device such as a personal computer). ) Form an image. As shown in the figure, the image forming machine includes an exposure unit 1, a developing device 2 (2a to 2d), a photosensitive drum (photosensitive member as referred to in the present invention) 3 (3a to 3d), and a charging means referred to in the present invention. As a charger 5 (5a to 5d), a cleaning unit 4 (4a to 4d), an intermediate transfer belt unit 8, a fixing device F, a paper transport path E, a paper feed cassette 10, a paper discharge tray 15, and the like. ing.

  Note that the image data handled in the image forming machine corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Accordingly, the developing device 2 (2a to 2d), the photosensitive drum 3 (3a to 3d), the charger 5 (5a to 5d), and the cleaning unit 4 (4a to 4d) form four types of images corresponding to the respective colors. In FIG. 1, a is set to black, b is set to cyan, c is set to magenta, and d is set to yellow to constitute four image stations.

  The photosensitive drum 3 is disposed (mounted) on the upper part of the image forming machine, and an electrostatic latent image corresponding to image data is formed by irradiation of laser light from the exposure unit 1 as will be described later. .

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. As shown in FIG. 1, in addition to a charger type charger, a contact type roller type or brush type A charger may be used.

  The exposure unit 1 is composed of a laser scanning unit (LSU) including a laser irradiation unit 1A and reflection mirrors 12, 12,. The laser irradiation unit 1A irradiates laser light for each hue based on the received image data. In addition, there is a method using, for example, an EL or LED writing head in which light emitting elements are arranged in an array. The exposure unit 1 has a function of forming an electrostatic latent image corresponding to the image data on the surface of the photosensitive drum by exposing the charged photosensitive drum 3 according to the input image data. Have.

  The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toners of respective colors (K, C, M, Y). As shown in FIG. 2, the developing device 2 includes a toner box (toner cartridge) 21 that is a toner container for containing toner, and a developing tank 22 filled with toner. Further, in the developing tank 22, a developing roller 23 (a metal developing sleeve is formed on the outer peripheral surface portion), a stirring roller and a supply roller (not shown) are accommodated. The toner is stored in the toner box 21 and is replenished into the developing tank 22 as necessary. A toner replenishing roller is disposed at the lower end opening of the toner box 21, and the toner in the toner box 21 is replenished to the lower developing tank 22 as the toner replenishing roller rotates. The stirring roller stirs the toner in the developing tank 22 and frictionally charges the toner. The supply roller supplies the frictionally charged toner toward the outer peripheral surface of the developing roller 23. The developing roller 23 supplies toner to the photosensitive drum 3.

  The developing roller 23 has a hollow cylindrical developing sleeve made of non-magnetic metal such as aluminum alloy, brass, SUS304 stainless steel or the like, and a magnet roller in which a plurality of magnet bodies (not shown) for generating a magnetic field are fixed. ing. The developing roller 23 is configured to convey and supply the toner to the developing unit in contact with the photosensitive drum 3 by magnetically attracting toner onto the surface while rotating only the developing sleeve. In addition, a doctor blade (not shown) is disposed above the developing roller 23 with a small gap, and the thickness of the toner layer adhering to the surface of the developing sleeve can be set to a predetermined thickness by the doctor blade. I am doing so.

  The cleaning unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer. The detailed configuration of the cleaning unit 4 will be described later.

  The intermediate transfer belt unit 8 disposed above the photosensitive drum 3 includes an intermediate transfer belt 7, an intermediate transfer belt drive roller 71, an intermediate transfer belt tension mechanism 73, an intermediate transfer belt driven roller 72, and a primary transfer roller. An intermediate transfer roller 6 (6a to 6d) and an intermediate transfer belt cleaning unit 9 are provided.

  The intermediate transfer belt drive roller 71, the intermediate transfer belt tension mechanism 73, the intermediate transfer roller 6, and the intermediate transfer belt driven roller 72 are stretched over the intermediate transfer belt 7, and the intermediate transfer belt 71 is rotated along with the rotation of the intermediate transfer belt drive roller 71. The belt 7 runs in the direction of arrow I.

  The intermediate transfer roller 6 is rotatably supported by a roller mounting portion in the intermediate transfer belt tension mechanism 73. As a result, the intermediate transfer rollers 6 a to 6 d are rotatably disposed on the inner surface side of the intermediate transfer belt 7 facing each photoconductor drum 3, and the toner image on the photoconductor drum 3 is also provided. Is transferred to the intermediate transfer belt 7.

  The intermediate transfer belt 7 is provided so as to be in contact with each photosensitive drum 3. Then, the toner images of the respective colors formed on the photosensitive drum 3 are sequentially superimposed and transferred onto the intermediate transfer belt 7, thereby forming a color toner image (multicolor toner composite image) on the intermediate transfer belt 7. It is like that. The intermediate transfer belt 7 is endlessly formed using a film having a thickness of about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by the intermediate transfer roller 6 in contact with the back side (inner surface side) of the intermediate transfer belt 7. That is, a high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charge polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image. The intermediate transfer roller 6 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 7. In this embodiment, a roller electrode is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the toner images visualized according to the hues on the photoreceptors 3a to 3d are stacked on the intermediate transfer belt 7 and become image information input to the apparatus. In this way, the laminated image information (composite image of multi-color toner) is transferred to a transfer roller that constitutes a transfer unit that is disposed at a contact position between a later-described sheet and the intermediate transfer belt 7 as the intermediate transfer belt 7 travels. 11 is transferred onto the paper.

  At this time, the intermediate transfer belt 7 and the transfer roller 11 are pressed against each other at a predetermined nip, and a voltage for transferring the toner onto the sheet is applied to the transfer roller 11 (opposite to the charging polarity (−) of the toner). Polarity (+) high voltage). Further, in order to obtain the nip constantly, the transfer roller 11 uses either the transfer roller 11 or the intermediate transfer belt drive roller 71 as a hard material (metal or the like) and the other as a soft material (elasticity such as an elastic roller). Rubber roller or foaming resin roller).

  Further, as described above, the toner adhered to the intermediate transfer belt 7 due to contact with the photosensitive drum 3 or the toner that is not transferred onto the sheet by the transfer roller 11 and remains on the intermediate transfer belt 7 Therefore, the intermediate transfer belt cleaning unit 9 removes and collects the toner. The intermediate transfer belt cleaning unit 9 includes a cleaning blade 91 as a cleaning member that comes into contact with the intermediate transfer belt 7. The intermediate transfer belt 7 contacts the intermediate transfer belt 7 in contact with the cleaning blade 91 from the back side. It is supported by a driven roller 72. The residual toner collected by the cleaning blade 91 falls and accumulates in a storage unit 92 installed below the cleaning blade 91.

  The paper feed cassette 10 is a cassette for storing sheets (recording paper) used for image formation, and is provided at the bottom of the image forming machine, that is, below the exposure unit 1. A paper discharge tray 15 provided in the upper part of the image forming machine is a tray for placing printed sheets face down.

  In addition, the image forming machine is provided with a paper conveyance path E for sending the sheets of the paper feed cassette 10 to the paper discharge tray 15 via the transfer roller 11 and the fixing device F. The paper transport path E extends in a substantially vertical direction from the paper discharge unit of the paper feed cassette 10 toward the paper discharge tray 15. Further, a pickup roller 16 (16-1), a registration roller 14, a transfer roller 11, a fixing device F, and a conveyance roller 25 (25) that conveys a sheet are provided in a paper conveyance path E from the paper cassette 10 to the paper discharge tray 15. -1,25-2, 25-3) and the like are disposed.

  The conveyance rollers 25 are small rollers for promoting and assisting conveyance of the sheet, and a plurality of conveyance rollers 25 are provided along the sheet conveyance path E. The pickup roller 16 is provided at the end of the paper feed cassette 10 and is a drawing roller that feeds sheets one by one from the paper feed cassette 10 to the paper transport path E.

  The registration roller 14 temporarily holds the sheet being conveyed on the sheet conveyance path E. The sheet has a function of conveying the sheet to a transfer unit (a nip portion between the transfer roller 11 and the intermediate transfer belt driving roller 71) at the timing when the leading edge of the toner image on the intermediate transfer belt 7 is aligned with the leading edge of the sheet. Yes.

  The fixing device F includes a heat roller 31, a pressure roller 32, and the like. The heat roller 31 and the pressure roller 32 rotate with a sheet interposed therebetween. The heat roller 31 is set by the control unit to have a predetermined fixing temperature based on a signal from a temperature detector (not shown), and is transferred to the sheet by thermocompression bonding the sheet together with the pressure roller 32. The resulting multicolor toner image is melted, mixed, and pressed to thermally fix the sheet.

  The sheet after the fixing of the multicolor toner image is transported on the paper transport path E by the transport rollers 25, and is discharged onto the paper discharge tray 15 with the multicolor toner image facing downward. .

  Next, the sheet conveyance path will be described in detail. The image forming apparatus is provided with a paper feed cassette 10 that stores sheets in advance, and a manual feed tray 20 that does not need to open and close the paper feed cassette 10 when a user prints a small number of sheets. ing.

  In both paper feeding methods, pickup rollers 16 (16-1 and 16-2) are arranged, respectively, so as to guide one sheet to the conveyance path.

  The sheet conveyed from the sheet feeding cassette 10 is conveyed to the registration roller 14 by the conveying roller 25-1 in the conveying path, and is transferred to the transfer roller 11 at a timing when the leading edge of the sheet and the leading edge of the image information on the intermediate transfer belt 7 are aligned. The image information is written on the sheet. Thereafter, the sheet passes through the fixing device F, whereby unfixed toner on the sheet is melted and fixed by heat, and is discharged from the discharge roller 25-3 to the discharge tray 15 via the conveying roller 25-2 ( (When requesting single-sided printing)

  On the other hand, the sheets stacked on the manual feed tray 20 are fed by the pickup roller 16-2, reach the registration roller 14 through a plurality of transport rollers (25-6, 25-5, 25-4), and thereafter. The sheet is discharged from the sheet feeding cassette 10 to the sheet discharge tray 15 through the same process as that of the sheet fed (when single-side printing is requested).

  At this time, if the print request content is a double-sided print request, the trailing edge of the sheet that has finished single-sided printing and has passed through the fixing device F as described above is chucked by the paper discharge roller 25-3, and the paper discharge roller 25 -3 reversely rotates and is guided to the switchback conveying path E1 having the conveying rollers (25-7, 25-8), and then the back surface printing is performed through the registration rollers 14, and then the sheet discharge tray. 15 will be discharged.

  In the actual image forming operation, the intermediate transfer roller 6 is subjected to intermediate transfer in response to a print request in order to reduce deterioration of the photosensitive drum 3 due to contact between the intermediate transfer belt 7 and the photosensitive drum 3. The intermediate transfer belt 7 and the photosensitive drum 3 can be separated from each other by moving the belt 7 in a direction in which the belt 7 is in contact with or separated from the belt 7.

  That is, the print request includes a color mode and a monochrome mode. In the color mode, each intermediate transfer roller 6 (6a to 6d) moves so as to come into contact with the back surface of the intermediate transfer belt 7, thereby performing the intermediate transfer. The surface of the belt 7 and each of the photosensitive drums 3 (3a to 3d) come into contact with each other so that the toner image of each hue can be primarily transferred to the intermediate transfer belt 7. On the other hand, in the monochrome mode, only the intermediate transfer roller 6a for black image formation moves so as to come into contact with the back surface of the intermediate transfer belt 7, thereby the surface of the intermediate transfer belt 7 and the photosensitive drum for black image formation. 3a comes into contact with the black toner image so that it can be primarily transferred to the intermediate transfer belt 7.

-Irradiation structure of static elimination light-
Next, a description will be given of an irradiation structure of static elimination light for removing residual charges on the surface of the photosensitive drum 3, which is a characteristic part of this embodiment.

  Before describing this irradiation structure, the cleaning unit 4 will be described. As shown in FIGS. 1 and 2 (sectional views schematically showing the photosensitive drum 3 and its peripheral structure), the cleaning unit 4 has a toner recovery roller 42 accommodated in a unit casing 41. A blade attachment plate 43 is fixed to the lower end portion of the unit casing 41, and a cleaning blade 44 is attached to the upper end portion of the blade attachment plate 43. The unit casing 41 and the blade mounting plate 43 constitute a casing member in the present invention. The upper end of the cleaning blade 44 is in contact with the surface of the photosensitive drum 3, and scrapes off residual toner remaining on the surface of the photosensitive drum after the image forming operation is completed. It is designed to collect the fall.

  The feature of the present embodiment is that the static elimination lamp 45 as the static elimination means for irradiating the static elimination light for removing the residual charge on the surface of the photosensitive drum 3 is the back side of the blade mounting plate 43, that is, the photosensitive drum. 3 is disposed on the opposite side of the arrangement position 3. The static elimination lamp 45 includes a lamp main body 46 and a reflector 47 for setting an irradiation direction of light from the lamp main body 46. The static elimination lamp 45 is directed in the direction of radiating static elimination light toward the casing 51 of the charger 5.

  In addition, a slit-like opening 43 a extending along the axial direction of the photosensitive drum 3 is formed in a portion of the blade mounting plate 43 that faces the irradiation direction of the static elimination light. The opening 43 a is formed so as to face one outer surface 52 of the outer surface of the casing 51 of the charger 5 that faces the upstream side in the rotation direction of the photosensitive drum 3.

  For this reason, when the charge removal lamp 45 is turned on, a part of the emitted charge removal light is blocked by the blade mounting plate 43 (the charge removal light irradiated to the part other than the formation part of the opening 43a is blocked), and the other The static elimination light passes through the opening 43a of the blade mounting plate 43, is applied to the outer surface 52 of the casing 51 of the charger 5, is reflected by the outer surface 52 of the casing, and is applied to the surface of the photosensitive drum 3 ( (See arrow A in FIG. 2). Of the surfaces of the casing 51 of the charger 5, only the surface 52 to which the charge removal light is applied is mirror-finished. Thereby, it is possible to irradiate the surface of the photosensitive drum 3 with almost no decrease in the amount of static elimination light, and it is possible to reliably remove residual charges.

  Specifically, for example, the irradiation direction of the static elimination light from the static elimination lamp 45 is the horizontal direction. On the other hand, in the charger 5, the casing outer surface 52 facing the cleaning unit 4 has a horizontal direction of about 60. It is arranged to have a tilt angle of °. As a result, the static elimination light reflected by the casing outer surface 52 is irradiated on the surface of the photosensitive drum 3 in a direction away from the charger 5 with an inclination angle of about 60 ° with respect to the horizontal direction. These angles are not limited to this, and it is sufficient that the static elimination light can be reflected toward a region between the contact position of the cleaning blade 44 with the photosensitive drum 3 and the charging region of the charger 5.

  Because of such a configuration, the static elimination device referred to in the present invention is constituted by the static elimination lamp 45, the opening 43a formed in the blade mounting plate 43, and the casing outer surface 52 of the charger 5.

  As a support structure for the charge removal lamp 45, the charge removal lamp 45 may be attached to the unit casing 41 or the blade mounting plate 43 of the cleaning unit 4, or a lamp support bracket (not shown) on the casing 51 of the charger 5. It is good also as a structure which attaches the static elimination lamp 45 to this lamp | ramp support bracket.

  FIG. 3 is a diagram for comparing the arrangement state of the static elimination lamp 45 of this embodiment and the arrangement state of the static elimination lamp a according to the conventional example. FIG. 3A shows the arrangement state of the static elimination lamp 45 of this embodiment, and FIG. 3B shows the arrangement state of the static elimination lamp a according to the conventional example.

  As shown in FIG. 3B, in the conventional apparatus, the cleaning unit b, the charge eliminating lamp a, and the charger c are arranged around the photosensitive drum d, and from the upstream side to the downstream side in the rotation direction. It was placed on a concentric circle at the center of rotation. In this case, in order to enable the arrangement of these members a, b, and c, the peripheral length of the outer surface of the photosensitive drum must be set long, and accordingly, the photosensitive drum d has a relatively large diameter. It was. Further, there is a possibility that the irradiation region (region α in FIG. 3B) of the static elimination light is irradiated to the charging region (region β in FIG. 3B) of the charger c, so-called stray light or leakage light. May occur, causing a variation in the potential of the surface of the photosensitive drum or a situation in which the surface of the photosensitive member cannot be charged.

  On the other hand, in the present embodiment shown in FIG. 3A, the static elimination lamp 45 is arranged on the back side of the blade mounting plate 43, so that the static elimination lamp 45 is provided between the cleaning unit 4 and the charger 5. Need not be placed. For this reason, the interval between the cleaning unit 4 and the charger 5 can be reduced, and the diameter of the photosensitive drum 3 can be reduced. In addition, the light path of the static elimination light A reflected by the casing outer surface 52 of the charger 5 is changed in the direction away from the charging area on the photosensitive drum 3 by the charger 5 (upper side in FIG. 3A). For this reason, the static elimination light A is applied to the charged region (region β in FIG. 3A) (so-called stray light or leakage light is generated), resulting in variations in the surface potential of the photosensitive drum. In other words, the charging characteristics can be stabilized by avoiding the situation where the surface of the photosensitive member cannot be charged.

  In this embodiment, since the cleaning unit 4 can be arranged in the direction approaching the charger 5, as shown in FIG. 3A, the center line L extending in the horizontal direction in the photosensitive drum 3 is longer than the center line L. The cleaning unit 4 can be disposed on the lower side. For this reason, the residual toner scraped off by the cleaning blade 44 can be smoothly dropped and supplied to the toner collecting roller 42 side by using gravity, and toner scattering can be suppressed. As a result, contamination by toner around the cleaning unit 4 can be prevented. Further, since the toner can be easily collected in this way, it is possible to set the pressing force of the cleaning blade 44 against the surface of the photosensitive drum 3 to be low, thereby extending the life of the photosensitive drum 3. It becomes possible.

  Furthermore, according to the configuration of the present embodiment, the static elimination lamp 45 is arranged at a position farther from the charger 5 than in the conventional one. In the vicinity of the static elimination lamp 45, the temperature increases with the lighting of the lamp body 46, and the air density is reduced in this portion. For this reason, it is possible to quickly guide the ozone generated in the charger 5 to the periphery of the static elimination lamp 45 (flow from a space having a high air density to a space having a low air density), and ozone is generated around the charger 5. It can avoid staying (dashed arrow B in Fig.3 (a)). Further, ozone can be quickly removed from the periphery of the charger 5 toward the downstream side in the rotation direction of the photosensitive drum 3 by the air flow generated as the photosensitive drum 3 rotates (see FIG. The broken line arrow C in 3 (a). Ozone can be removed from the periphery of the photosensitive drum 3 by these actions, and it becomes possible to suppress the ozone deterioration of the photosensitive drum 3 and to extend the life of the photosensitive drum 3.

-Other embodiments-
In the embodiments described above, the case where the present invention is applied to an image forming machine configured as a color printer has been described. The present invention is not limited to this, and can also be applied to an image forming machine configured as a color copying machine or an image forming machine configured as a multi-function machine having a plurality of functions. It can also be applied to monochrome type printers and copiers.

  In addition, as the arrangement form of the charge removal lamp 45, in the above embodiment, the charge removal lamp 45 is disposed on the back side (anti-photosensitive drum side) of the blade attachment plate 43 and passes through the opening 43a of the blade attachment plate 43 to irradiate the removal light. I was trying to do it. The present invention is not limited to this, and a gap is formed between the cleaning unit 4 and the charger 5 so that the charge-removing light can pass. The charge-removing light passing through the gap is applied to the casing outer surface 52 of the charger 5. In addition, the static elimination lamp 45 may be arranged so as to be irradiated on the surface of the photosensitive drum 3 after being reflected by the casing outer surface 52.

  In the above embodiment, only the surface 52 of the casing 51 of the charger 5 on which the static elimination light is irradiated is mirror-finished, but a matte finish may be applied instead. This satin finish is also called a shot finish and refers to a process in which minute irregularities are randomly formed on the surface.

  In the above-described embodiment, the paper discharge unit includes only one paper discharge tray 15. However, as indicated by a virtual line in FIG. 1, the recording paper discharge position is set for each JOB of the image forming operation. You may make it provide the JOB separator 15A to change. As a result, when a plurality of JOBs are received substantially simultaneously, sorting of printed matter for each JOB formed with an image is facilitated.

1 is a diagram illustrating an internal configuration of an image forming machine according to an embodiment. 2 is a cross-sectional view schematically showing a photosensitive drum and its peripheral structure. FIG. (A) is a figure which shows the arrangement | positioning state of the static elimination lamp which concerns on embodiment, (b) is a figure which shows the arrangement | positioning state of the static elimination lamp concerning a prior art example.

Explanation of symbols

3 Photosensitive drum (photosensitive member)
4 Cleaning unit 41 Unit casing 43 Blade mounting plate 43a Opening 45 Static elimination lamp (static elimination means)
5 Charger (charging means)
51 Casing 52 Casing outer surface A Static elimination light

Claims (1)

In a static eliminator provided with a static eliminator disposed at a position close to a charging means for charging the surface of a photoconductor and emitting static radiation for removing residual charges on the surface of the photoconductor after an image forming operation. ,
A cleaning unit for removing toner remaining on the surface of the photoconductor after the image forming operation is disposed around the photoconductor, and a casing member of the cleaning unit extends along the axial direction of the photoconductor. A slit-shaped opening is formed so as to face one outer surface of the outer surface of the casing of the charging unit facing the upstream side in the rotation direction of the photosensitive member ,
Discharging means is disposed on the rear side is anti photoconductor side of the cleaning unit, neutralization irradiation light emitted from the charge removing means, passes through the opening of the casing member while straight through the air, the A configuration in which the outer surface of the casing of the charging unit hits one outer surface facing the upstream side in the rotation direction of the photoconductor, reflects away from the charging area of the photoconductor, and irradiates the surface of the photoconductor while traveling straight in the air. The static eliminator characterized by becoming.

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