JP2007094203A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus easily performing image formation without any image faults such as a horizontal stripe or a drum positive ghost in minimum space and at low cost by installing a discharging apparatus in a most efficient position other than a process cartridge. <P>SOLUTION: A discharging exposure means 70 discharges an image carrier 1 from which transfer residual toner is removed. The discharging exposure means 70 includes: a light source 71 carrying out exposure to the image carrier 1 from a side surface direction outside an image forming region for the image carrier 1 on the upstream side of a cleaning means and reflecting means 72 installed on a side surface outside an image forming region of the image carrier 1 on the opposite side facing the light source 71. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic system, and relates to, for example, a copying machine, a printer, a facsimile machine, and the like.

  Conventionally, in an electrophotographic image forming apparatus, a corona charger has been used as a charging processing means for an image carrier such as an electrophotographic photosensitive member. In recent years, since it has advantages such as low ozone, low power, etc., a contact charging device, that is, a method for charging a charged object by bringing a charged member such as a photosensitive member into contact with a charged member applied with voltage. These devices have been put into practical use. In particular, a roller charging apparatus using a conductive roller as a charging member is preferably used from the viewpoint of stabilization of charging.

  In a roller charging type contact charging device, a conductive elastic roller as a charging member is brought into pressure contact with a member to be charged, and a voltage is applied thereto to charge the member to be charged.

  Specifically, since charging is performed by discharging from a charging member to an object to be charged, charging is started by applying a voltage higher than a certain threshold voltage.

  As an example, a charging process is performed by pressing a charging roller against an electrophotographic OPC photosensitive body (hereinafter referred to as “photosensitive drum”) having a film thickness of 15 μm, which is a normal drum shape, as a member to be charged. May be performed. In this case, if a voltage of about −560 V is applied to the charging roller, the surface potential of the photosensitive drum starts to rise, and thereafter, the surface potential of the photosensitive member increases linearly with respect to the applied voltage. .

  When this threshold voltage is defined as the charging start voltage Vth, in order to obtain the photosensitive drum surface potential VD required for electrophotography, it is necessary to apply a DC voltage of charging potential: Vth + VD to the charging roller. Such a contact charging method in which only a DC voltage is applied to the contact charging member to charge the object to be charged is called a DC charging method.

  However, when this DC charging is performed, image detriment occurs, particularly in a high humidity environment. Image harm called “drum positive ghost” mainly caused by the difference in charged potential on the photosensitive drum, mainly “horizontal streaks generated in halftone images” caused by potential disturbance on the photosensitive drum before the charging process It is.

  In order to prevent such image detrimental effects, i.e., horizontal streaks and drum positive ghosts that occur in halftone images, so-called neutralization means that neutralizes the residual potential by irradiating the photosensitive drum with light before the charging step. It is known to be effective.

  FIG. 9 shows an image forming apparatus equipped with a conventional static eliminator. In FIG. 9, the photosensitive drum 101 is uniformly charged by the charging roller 102. Next, a laser beam modulated in accordance with an image signal from the scanner unit 103 including a laser, a polygon mirror, and a lens system is scanned out. The laser light is reflected by the folding mirror 104 and irradiated with the laser light on the surface of the photosensitive drum to form an electrostatic latent image. The electrostatic latent image formed by the laser light irradiation is developed as a toner image by the toner 106 in the developing device 105 to be visualized.

  On the other hand, the transfer material P stored in the cassette 107 is supplied to the registration roller 110 by the paper feed roller 109 in synchronization with the formation of the latent image on the photosensitive drum 101. The transfer material P is conveyed to a transfer charger 111 including a transfer roller in synchronization with the leading edge of the latent image formed on the photosensitive drum 101 by the registration roller 110. The toner image is transferred onto the transfer material P by the transfer charger 111. The transfer material 108 onto which the toner image has been transferred is permanently fixed to the toner image by the fixing device 112, and is finally discharged outside the apparatus.

  The toner remaining on the photosensitive drum 101 is removed by a cleaning device 113 having an elastic blade 113a. The photosensitive drum 101, the charging roller 102, the developing device 105, and the cleaning device 113 are provided as a unitized process cartridge CR.

  Here, the generation mechanism of the horizontal white streak appearing after one turn of the photosensitive drum from the leading edge of the transfer material, which is particularly remarkable as an image defect, will be described.

  FIG. 10 is an enlarged view of the vicinity of the transfer nip N where the photosensitive drum 101 and the transfer charger 111 face each other. Until the transfer material P enters the transfer nip N as shown in FIG. 10A, the potential on the photosensitive drum 101 before transfer is VD charged by the charging roller 102. The potential on the photosensitive drum 101 after passing through the transfer nip N drops to Vtr lower than VD due to the transfer current.

  Next, when the leading edge of the transfer material P enters the nip N between the photosensitive drum 101 and the transfer charger 111 as shown in FIG. 10B, both members come into contact between the photosensitive drum 101 and the transfer charger 111. There is no air gap G. In this portion, since the surface of the photosensitive drum 101 is not easily neutralized by the transfer current, a portion having a value Vtr0 higher than Vtr is formed. Further, when the transfer material P advances through the transfer nip N, as shown in FIG. 10C, the potential on the photosensitive drum 101 after the transfer nip N becomes Vtr again.

  The potential Vtr on the photosensitive drum 101 returns to VD when charged by the charging roller 102 again. However, since the potential before charging is higher than Vtr at the Vtr0 portion, the potential after charging is also increased. For this reason, when a halftone image or the like having a uniform density is printed after one round of the photosensitive drum in the portion before and after Vtr0, the potential of the portion corresponding to Vtr0 is high, resulting in a white stripe-like horizontal stripe image.

  The description has been given above using the configuration in which the transfer charger 111 directly contacts the transfer material P. However, when the transfer charger 111 is a sponge roller with low hardness, the gap is small, but when the resin belt for transporting a transfer material with higher hardness is superimposed on the transfer charger 111, the gap is large. As a result, white lines are likely to occur.

  As described above, in the DC charging type contact charging device, it is difficult to completely erase the potential history on the photosensitive drum after the transfer, so that the static elimination exposure means for irradiating the photosensitive drum surface with light after the transfer becomes effective. .

  As the static elimination exposure means as described above, a configuration that can reduce the number of LEDs in a space-saving manner as shown in Patent Document 1 has been proposed. 11 and 12 show an example of the static elimination exposure means.

  FIG. 11 is a schematic view of the image forming apparatus viewed from the X direction in FIG. In FIG. 11, the exterior portion of the image forming apparatus, the developing device 105 of the process cartridge CR, and the cleaning device 113 are omitted.

  As shown in FIGS. 11 and 12, the static eliminator 50 in this example is equipped with LED lamps 51 and 52 as light sources provided on the front side and the back side of the image forming apparatus main body 100A, and the process cartridge CR. And a rod-shaped light guide 53. The light guide 53 is formed with light incident portions 54 and 55 facing both the LED lamps 51 and 52, and functions as a light irradiating member for irradiating the guided light to the longitudinal surface of the photosensitive drum.

  In this example, as shown in FIG. 11, the LED lamps 51 and 52 are provided on the image forming apparatus main body 100 </ b> A side, and are disposed in an area outside the static elimination area (width L) of the photosensitive drum 1. Further, light shielding members 56 and 57 are provided to surround the outer periphery of the LED lamps 51 and 52 so as to prevent light from the LED lamps 51 and 52 from unnecessarily exposing the end of the photosensitive drum 101.

  Next, the material, shape, function, and arrangement of the rod-shaped light guide 53 will be described.

  Conventionally, as shown in FIG. 11, the main feature is that the rod-shaped light guide 53 is mounted on the process cartridge CR. FIG. 12A shows the shape of the rod-shaped light guide 53.

  The rod-shaped light guide 53 includes a light guide member 58 that transmits and reflects light, and a white resin case 59 for increasing the reflection efficiency. As the material of the light guide member 58, acrylic resin, polycarbonate, polystyrene, glass, or the like having high light transmittance is used.

  Further, as shown in FIG. 12A, the white resin case 59 has “light incident portions 54 and 55” at both ends, and “openings 60” having a predetermined width w on the side surfaces. The opening 60 is disposed opposite to the photosensitive drum 101.

  FIG.12 (b) is the figure seen from the Z direction in Fig.12 (a). As can be seen from FIG. 12B, the light guide surface 61 on the opposite side of the opening 60 of the white resin case 59 has a number of V-shaped notches. Light incident from the light incident portions 54 and 55 of the rod-shaped light guide 53 is reflected by the V-shaped notch portions 61 to change the optical path, and the light guide longitudinal direction from the opening 60 of the white resin case 59. Irradiated in a direction perpendicular to

  In other words, this light is irradiated as “static elimination light” on the surface of the photosensitive drum 101 with a predetermined static elimination width L (see FIG. 10).

When the light guide 53 is used as a light irradiating member to the photosensitive drum 101 as in this example, the light amount ripple (fluctuation width) on the photosensitive drum 101 compared to a conventional chip array type in which a plurality of LEDs are arranged. Is small and uniform charge removal is possible.
JP 2001-142365 A

  In recent years, however, the multicolor image forming apparatus has been reduced in size and the photosensitive drum diameter of the process cartridge has been reduced. Therefore, it is necessary to secure a space for attaching a light guide around the photosensitive drum as in the past. Has become very difficult.

  Further, since the conventional static eliminating device 50 mounts the light guide 53 on the process cartridge CR, it has been a factor that increases the cost of the process cartridge CR.

  In addition, although the light guide has no life, it has been replaced with the life of the process cartridge, which is not desirable from the viewpoint of ecology. In particular, in the case of a multicolor image forming apparatus having a plurality of process cartridges, the user bears the cost of a large number of light guides that do not need to be replaced.

  SUMMARY OF THE INVENTION An object of the present invention is to obtain an image formation free from image defects such as horizontal stripes and drum positive ghosts in a minimal space at a low cost and easily by disposing the static elimination device at the most efficient place other than the process cartridge. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

  Another object of the present invention is to dispose an image neutralizing device such as horizontal stripes and drum positive ghosts by disposing the irradiation unit and the reflection unit or only the reflection unit on the transfer material carrier or the intermediate transfer member. An image forming apparatus that can be obtained is provided.

The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention
Image carrier,
Charging means for charging the image carrier to a predetermined polarity;
Exposure means for exposing the charged image carrier to form an electrostatic latent image according to image information;
Developing means for causing toner to adhere to the electrostatic latent image to be visualized as a toner image;
A transfer means for transferring the toner image to a transfer material carried on a transfer material carrier or an intermediate transfer body;
A cleaning unit provided on the downstream side of the transfer unit with respect to the rotation direction of the image carrier and removing transfer residual toner remaining on the image carrier after the transfer by the transfer unit;
Static elimination exposure means for neutralizing the image carrier from which the transfer residual toner has been removed,
In an image forming apparatus comprising:
The static elimination exposure means includes
The image carrier is exposed from the lateral direction outside the image forming area of the image carrier on the downstream side of the transfer unit and the upstream side of the cleaning unit with respect to the rotation direction of the image carrier. A light source;
Reflecting means disposed on the side surface outside the image forming area of the image carrier opposite to the light source;
An image forming apparatus comprising:

  According to the present invention, it is possible to dispose only the irradiation unit and the reflection unit, or only the reflection unit on the transfer material carrier or the intermediate transfer member having the highest efficiency other than the process cartridge. Therefore, there is no need to install a high-cost apparatus on the apparatus main body side that irradiates the image carrier with a plurality of LEDs arranged side by side, and a light guide is not provided on the process cartridge side to increase the cost of the cartridge. . Therefore, the image forming apparatus can be easily downsized, and image defects such as horizontal streaks and drum positive ghosts generated in a halftone image can be prevented with a low-cost configuration.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

  However, the materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.

Example 1
In this embodiment, the image forming apparatus according to the present invention is an electrophotographic full-color laser beam printer. First, the overall configuration of the image forming apparatus will be described.

[Entire configuration of image forming apparatus]
Referring to FIG. 1, the entire configuration of a full-color laser beam printer 100 which is an image forming apparatus of this embodiment is shown.

  First, the overall configuration of the color image forming apparatus will be described together with the image forming operation with reference to FIG.

  The color image forming apparatus 100 according to the present embodiment transports a recording medium, that is, a transfer material P to an image forming unit and forms an image by an electrophotographic method. The image forming unit is provided with four image forming units, and sequentially transfers toner images of different colors onto the transfer material P to record a color image.

  The four image forming units 20 (20Y, 20M, 20C, 20K) form yellow (Y), magenta (M), cyan (C), and black (K) toner images in order from the bottom. . Each image forming unit 20 (20Y, 20M, 20C, 20K) has the same configuration except that the color of the toner is different.

  That is, each image forming means 20 (20Y, 20M, 20C, 20K) is a drum-shaped electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 1 (1Y, 1M, 1C, 1K) as an image carrier. Have

  Around the photosensitive drum 1, a primary charging device 2 (2Y, 2M, 2C, 2K) as a charging unit, a developing device 4 (4Y, 4M, 4C, 4K) as a developing unit, and a cleaning device 5 (5Y as a cleaning unit). 5M, 5C, 5K). Then, the surface of the rotating photosensitive drum 1 is uniformly charged by the primary charging device 2, and an electrostatic latent image is formed by irradiating the exposure unit 3 with laser light corresponding to the image signal, and the latent image is developed. The toner is developed by means 4 and visualized.

  Here, in this embodiment, the photosensitive drum 1, the charging device 2, the developing device 4, and the cleaning device 6 are integrally formed into a cartridge, and a process cartridge 20 (20 Y, 20 M, 20 C, 20 K) serving as an image forming unit is used. Forming. A transfer / conveying belt unit 6A is disposed to face the process cartridge 20 (20Y, 20M, 20C, 20K).

  A transfer conveyance belt 6 is disposed so as to be able to contact each photosensitive drum 1. The transport belt 6 is an endless belt that is stretched around a drive roller 7a, a driven roller 7b, and a tension roller 7c provided in the transfer transport belt unit 6A. The drive roller 7a is driven and rotated to respond to an image forming operation. And rotate in the direction of arrow a. Further, transfer rollers 8 (8Y, 8M, 8C, 8K) are arranged at positions facing the respective photosensitive drums 1 with the conveying belt 6 interposed therebetween.

  At the time of image formation, transfer as a recording medium is performed by a feeding roller 10 from a cassette 9 loaded at the lower part of the apparatus body so as to synchronize with the formation of a toner image by each image forming means 20 (20Y, 20M, 20C, 20K). A transfer material P such as paper is fed. The transfer material P is attracted to the transport belt 6 that rotates in the direction of arrow a by applying a bias to the suction roller 11 and transported to the transfer position of each image forming unit. The toner image on the photosensitive drum 1 is transferred to the transfer material P by applying a bias to the transfer roller 8 disposed at the transfer position. On the transfer material P, color toner images are superimposed to form a color image. The transfer material P is conveyed to the fixing unit 12 and is discharged to the discharge unit 13 at the top of the apparatus after the toner is fixed.

  Note that the image forming apparatus 100 according to the present embodiment can form not only the full-color image operation but also a monochrome image. When a monochrome image is formed, only the transfer roller 8K of the black image forming unit 20K is brought into contact with the transport belt 6. Then, the transfer rollers 8Y, 8M, and 8C of the other yellow, magenta, and cyan image forming units 20Y, 20M, and 20C are separated from the conveyance belt 6. A monochrome image can be obtained by transferring only the black image formed by the black image forming unit 20K to the transfer material P on the sheet conveyed by the conveyance belt 6.

  In recent years, in multicolor image forming apparatuses, the diameter and interval of the photosensitive drum 1 have become very small in order to reduce the size and cost. For this reason, the exposure means for static elimination, that is, the space for installing the static elimination exposure means has been very limited.

  FIG. 2 schematically shows yellow and magenta image forming units, that is, process cartridges 20Y and 20M. The other cyan and black image forming units, that is, the process cartridges 20C and 20K have the same configuration and are omitted here.

  According to the present exemplary embodiment, a static elimination exposure unit 70 that irradiates the photosensitive drum with light as a static elimination device is provided at a predetermined position adjacent to each process cartridge 20.

  The static elimination exposure means 70 includes an LED 71 as a light source. In each process cartridge 20, the LED 71 is installed at an angle at which a portion surrounded by the photosensitive drum 1, the transfer conveyance belt 6, the shutter 22 of the photosensitive drum 1, and the frame 21 of the process cartridge 20 is irradiated from the side. Yes.

  The shutter 22 is swingably attached to the process cartridge frame 21 and functions to block the photosensitive drum 1 from outside light when the process cartridge 20 is removed from the apparatus main body. That is, as indicated by a one-dot chain line in FIG. 2, when the process cartridge 20 is detached from the apparatus main body, the shutter 22 swings toward the side where the photosensitive drum 1 is exposed to shield the photosensitive drum 1 from light. When the process cartridge is mounted on the apparatus main body, as shown by a solid line in FIG. 2, the process cartridge is positioned so that only the surface of the photosensitive drum 1 facing the transfer conveyance belt 6 is exposed.

  In the image forming apparatus having the configuration shown in the present embodiment, in practice, in the region surrounded by the frame 21 of the process cartridge 20 and the transfer belt 6, the distance between the transfer material P to be conveyed is extremely narrow. . For this reason, it is very difficult to install a conventional light guide 53 (see FIGS. 11 and 12) in a space sandwiched between the process cartridge frame 21 and the transfer belt 6.

  Therefore, in this embodiment, as described above, the light guide is not provided, and the light of the LED 71 is directly applied to the photosensitive drum 1.

  FIG. 3 is a view of the vicinity of the image forming unit in FIG. 2 as viewed obliquely. In this embodiment, in the static elimination exposure means 70, the optical axis of the LED 71 is set in parallel with the rotation axis of the photosensitive drum 1. Further, the luminous flux of the LED is configured to be projected onto an area after transfer on the photosensitive drum 1.

  When the light of the LED 71 irradiates the surface of the photosensitive drum before transfer in the adjacent image forming unit, image defects such as scattering of line images are caused. Therefore, it is necessary to shield light.

  On the other hand, in this embodiment, the shutter 22 that shields the photosensitive drum 1 when the process cartridge 20 is originally removed from the apparatus main body has a structure that blocks the LED light from other adjacent cartridges.

  That is, in FIG. 2, the light of the LED 71Y that irradiates the photosensitive drum 1Y of the process cartridge 20Y is shielded by the shutter 22M provided in the process cartridge 20M with respect to the adjacent process cartridge 20M. Therefore, the light of the LED 71Y for the photosensitive drum 1Y does not irradiate the surface of the photosensitive drum 1M before transfer in the adjacent process cartridge 20M.

  With the above-described configuration of the present embodiment, it is not necessary to provide a special light shielding unit for the static elimination exposure unit 70.

  On the other hand, since the transfer / conveying belt (ETB) 6 having a very high gloss is used in this embodiment, the light of the LED 71 is emitted from the ETB 6 and the photosensitive drum 1 particularly in a portion where white streaks occur at the leading end of the paper. By repeatedly reflecting on the surface, light can be effectively guided to the end of the photosensitive drum opposite to the irradiation side.

  The LED 71 preferably has a peak wavelength in the photosensitive wavelength range of the photosensitive drum 1, a narrow directivity angle, and a high luminous intensity. In this example, Toshiba's TLRE20TP type was used. This LED has a peak wavelength of 630 nm, a directivity angle of 7 degrees, and a very high luminous intensity of 7000 mcd. Therefore, it is possible to satisfactorily irradiate the entire length of the photosensitive drum 1 without providing a special light collecting means.

  In this embodiment, the optical axis of the LED 71 is set in parallel with the rotation axis of the photosensitive drum 1, but for example, the optical axis of the LED 71 is so small that it intersects the surface of the photosensitive drum at the end opposite to the photosensitive drum. It is also effective to provide an angle.

  Further, as understood with reference to FIGS. 4 to 6, according to the present embodiment, the LED 71 is provided on the high-voltage board 100B for mounting the electrical component installed on the apparatus main body (frame body) 100A. it can. 100 A of frame bodies are normally produced with a metal material, for example, a steel plate.

  Then, a transfer conveyance belt in which a reflection plate 72 that reflects the light of the LED 71 on the side of the photosensitive drum 1 opposite to the LED 71 is rotatably suspended by rollers 7a, 7b, and 7c. It is provided on the belt frame 16 of the unit 6A.

  As a material of the reflector 72, in this embodiment, an aluminum deposited film obtained by depositing aluminum on a PET film is attached and installed on the belt frame 16. However, the support position of the reflection plate 72 may be any position as long as it does not interfere with the attaching / detaching operation of the process cartridge 20 and does not interfere with the attaching / detaching operation of the transfer conveyance belt unit 6A.

  In this embodiment, a reflector 72 is installed at a position that fits between the photosensitive drum 1 and the process cartridge frame 21 and is arranged at a position where there is no obstacle to the photosensitive drum 1 for efficiency.

  Further, by attaching the reflection plate 72 to the transfer conveyance belt frame 16, the reflection plate 72 can be moved away from the process cartridge 20. Further, it is possible to cover the reflector 72 so that the scattered toner does not fall on the reflector 72.

  As shown in FIG. 4, the reflection plate 72 is installed such that the reflection angle at the reflection position 72 is focused on a point where the center of the reflected light is centered on 1/4 (the reflection plate side) of the photosensitive drum. did. As a result, when a flat reflector is used, it is possible to irradiate the end of the photosensitive drum opposite to the LED where the light coming from the LED 71 is particularly weak. This angle can be arbitrarily changed by the surface installation angle depending on the light quantity and configuration of the LED. However, if the tilt angle is too large, only the end near the reflector is irradiated. Therefore, it is desirable to determine the installation angle according to the position of the reflector support portion.

  With the configuration as described above, the LED side of the photosensitive drum surface is neutralized by the light L-LED from the LED 71 and the reflection plate side is neutralized by the light L-Mirror from the reflection plate 72 as shown by the light flux in FIG. It becomes possible to do.

  Table 1 shows the surface potential of the photosensitive drum before and after static elimination in this embodiment.

  As is apparent from Table 1, when the configuration of the present embodiment is adopted, the potential on the side opposite to the LED 71 of the photosensitive drum 1 can be lowered to a potential having a sufficient margin. Therefore, even in a corner case with very severe conditions, it is possible to make white stripes completely invisible by adopting the configuration of this embodiment.

  Further, in the configuration of this embodiment, there is one LED 71, and the reflector 72 can be made uniform with static elimination light by a very low cost member such as an aluminum vapor deposition film, so that static elimination can be achieved without increasing the cost of the image forming apparatus. The exposure means 70 can be mounted.

  In this embodiment, an aluminum vapor deposition film is used as the reflecting material of the reflecting plate 72. However, the other reflecting materials are not limited to the configuration of the present embodiment, such as a stainless steel plate and nickel plating, but have various configurations. It is possible.

  Further, as shown in FIG. 6, it is also possible to apply the reflected light evenly to the photosensitive drum 1 by using convex reflection on the reflecting plate 72 and making the reflected light diffuse.

  According to the present embodiment having the above-described configuration, it is not necessary to install a high-cost apparatus on the main body side that irradiates the photosensitive drum with a plurality of LEDs arranged.

  Further, it is possible to achieve a static elimination means that does not increase the cost of the cartridge by providing a light guide on the process cartridge side. Therefore, it is possible to provide an image forming apparatus that can easily reduce the size of the image forming apparatus and can prevent image adverse effects such as horizontal stripes and drum positive ghosts generated in a halftone image with a low-cost configuration.

Example 2
Next, a second embodiment of the present invention will be described. Since the overall configuration of the image forming apparatus of the present embodiment is the same as that described in the first embodiment, components having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals, and again here. Detailed description of is omitted. In the present embodiment, the same effects as those of the first embodiment can be achieved, and further, there are advantages described below.

  In FIG. 7, the structure of the principal part of a present Example is shown. Hereinafter, description will be made based on this figure.

  In the first embodiment, the LED 71 is held on the high-voltage board 100B installed on the apparatus main body frame 100A. In the second embodiment, the LED 71 and the reflection plate 72 are attached to the transfer conveyance belt frame 16 (16a, 16b) of the transfer conveyance belt unit 6A.

  The following advantages are obtained by mounting the static elimination exposure means 70 on the transfer / conveying belt frame 16 (16a, 16b).

  That is, the transfer / conveying belt frame 16 has no obstacle to the photosensitive drum 1, for example, a user access handle of the process cartridge 20, a process cartridge frame 21 that holds the photosensitive drum 1, and the like. Therefore, the LED 71 having a smaller light quantity can be used. In addition, since the irradiation unit (LED 71) and the reflection unit (reflection plate 72) can be held in the transfer conveyance belt frame 16, the light emission from the high-voltage substrate 100B attached to the apparatus main body frame 100A with respect to the photosensitive drum 1 is further improved. Light emission reflection is possible with high accuracy.

Example 3
In the first and second embodiments, the image forming apparatus that transfers the developer image (toner image) formed on the photosensitive drum 1 to the transfer material P carried on the transfer conveyance belt 6 has been described. However, the present invention is a so-called intermediate transfer type image forming apparatus in which a developer image (toner image) formed on the photosensitive drum 1 is temporarily transferred to an intermediate transfer member and transferred from the intermediate transfer member to a transfer material P. However, the above-described configuration of the present invention can be similarly applied to achieve the same function and effect.

  FIG. 8 shows an example of such an intermediate transfer type image forming apparatus. The image forming apparatus of the present embodiment has the same overall configuration as described in the first embodiment.

  However, the present embodiment is different from the first embodiment only in that the transfer conveyance belt unit 6A provided for conveying the transfer material P in the first embodiment is an intermediate transfer belt unit 6B.

  Accordingly, members having the same configuration and function are denoted by the same reference numerals, and the description made in the first embodiment is used, and the description thereof is omitted here. Hereinafter, differences between the image forming apparatuses of the present embodiment will be briefly described.

  The intermediate transfer belt unit 6B in this embodiment includes an intermediate transfer belt 60 that is an endless belt instead of the transfer conveyance belt 6 in the first embodiment, and each image forming unit 20 (20Y, 20M, 20C, 20K), the developer image (toner image) on the photosensitive drum 1 (1Y, 1M, 1C, 1K) is directly transferred onto the intermediate transfer belt 60.

  The color toner image formed in each image forming unit and transferred to the intermediate transfer belt 60 is transferred to the second transfer unit in which the transfer roller 13 as the second transfer unit is arranged instead of the suction roller 11 of the first embodiment. Then, the images are transferred all at once onto the transfer material P conveyed from the paper feed cassette 9.

  The transfer material P onto which the toner images have been collectively transferred is fixed by the fixing unit 12 and discharged to the outside.

  Also in the intermediate transfer type image forming apparatus of this embodiment, the static elimination exposure means 70 as the static elimination apparatus having the same configuration as described in the first and second embodiments can be arranged in the same manner, and the same function and effect can be obtained. Can be achieved.

  That is, also in this embodiment, it is not necessary to install a high-cost apparatus on the main body side that irradiates the photosensitive drum with a plurality of LEDs arranged.

  Further, it is possible to achieve a static elimination means that does not increase the cost of the cartridge by providing a light guide on the process cartridge side. Therefore, it is possible to provide an image forming apparatus that can easily reduce the size of the image forming apparatus and can prevent image adverse effects such as horizontal stripes and drum positive ghosts generated in a halftone image with a low-cost configuration.

1 is a schematic cross-sectional view of an embodiment of an image forming apparatus according to the present invention. 3 is a schematic cross-sectional view for explaining a static eliminator disposed adjacent to a process cartridge constituting an image forming unit. FIG. FIG. 3 is a schematic perspective view for explaining a static eliminator disposed adjacent to a process cartridge constituting an image forming unit. In the static elimination apparatus according to this invention, it is explanatory drawing for demonstrating the Example whose reflecting plate is a plane plate. It is explanatory drawing for demonstrating the state which provided the reflecting plate on the transfer conveyance belt frame. It is explanatory drawing for demonstrating the Example whose reflecting plate is convex shape in the static elimination apparatus according to this invention. It is explanatory drawing for demonstrating the state which provided LED and the reflecting plate on the transfer conveyance belt frame. FIG. 5 is a schematic cross-sectional view of another embodiment of an image forming apparatus according to the present invention. It is a schematic sectional view of a conventional image forming apparatus. It is explanatory drawing for demonstrating the state of the electric potential on the photosensitive drum after transfer. FIG. 10 is a schematic cross-sectional view of a static eliminator in a conventional image forming apparatus. It is a perspective view of the static elimination apparatus in the conventional image forming apparatus.

Explanation of symbols

1 (1Y, 1M, 1C, 1K) Photosensitive drum (image carrier)
2 (2Y, 2M, 2C, 2K) Charging roller (charging unit)
3 (3Y, 3M, 3C, 3K) Laser beam scanner (exposure means)
4 (4Y, 4M, 4C, 4K) Developing device (developing means)
6 Transfer conveyor belt (transfer material carrier)
6A Transfer conveyor belt unit 6B Intermediate transfer belt unit 7a Drive roller 7b Driven roller 7c Tension roller 8 Transfer roller (transfer means)
9 Cassette (paper feeder)
10 Feeding roller 11 Adsorption roller 12 Fixing device (fixing means)
13 Secondary transfer roller (secondary transfer means)
16 Belt frame 20 (20Y, 20M, 20C, 20K) Image forming unit (process cartridge)
60 Intermediate transfer belt (intermediate transfer member)
70 Static elimination device (static elimination exposure means)
71 LED (light source)
72 reflector

Claims (12)

Image carrier,
Charging means for charging the image carrier to a predetermined polarity;
Exposure means for exposing the charged image carrier to form an electrostatic latent image according to image information;
Developing means for causing toner to adhere to the electrostatic latent image to be visualized as a toner image;
A transfer means for transferring the toner image to a transfer material carried on a transfer material carrier or an intermediate transfer body;
A cleaning unit provided on the downstream side of the transfer unit with respect to the rotation direction of the image carrier and removing transfer residual toner remaining on the image carrier after the transfer by the transfer unit;
Static elimination exposure means for neutralizing the image carrier from which the transfer residual toner has been removed,
In an image forming apparatus comprising:
The static elimination exposure means includes
The image carrier is exposed from the lateral direction outside the image forming area of the image carrier on the downstream side of the transfer unit and the upstream side of the cleaning unit with respect to the rotation direction of the image carrier. A light source;
Reflecting means disposed on the side surface outside the image forming area of the image carrier opposite to the light source;
An image forming apparatus comprising: The image carrier, the charging unit, the developing unit, and the cleaning unit are integrated into a unit, and are a process cartridge that is detachable from the image forming apparatus main body.
2. The image forming apparatus according to claim 1, wherein the light source and the reflection unit of the static elimination exposure unit are mounted on a member that is not the process cartridge. The transfer material carrier or the intermediate transfer member is an endless belt, and is stretched around a plurality of support rollers to form a belt unit.
The image forming apparatus according to claim 2, wherein at least the reflection unit of the static elimination exposure unit is attached to the belt unit of the transfer material carrier or the intermediate transfer member.   4. The image forming apparatus according to claim 2, wherein the light source of the static elimination exposure unit is mounted on the main body side of the image forming apparatus.   5. The image forming apparatus according to claim 4, wherein the light source of the static elimination exposure unit is mounted on an electrical component substrate provided outside a frame forming the image forming apparatus main body.   6. The image forming apparatus according to claim 5, wherein the frame forming the image forming apparatus main body is formed of a conductive material.   The image forming apparatus according to claim 1, wherein the reflection unit is a planar reflection plate.   The image forming apparatus according to claim 7, wherein the reflecting surface of the reflecting plate is arranged so that a reflection angle thereof is closer to a reflecting plate side than a center of the image holding member with respect to a longitudinal direction of the image bearing member.   The image forming apparatus according to claim 1, wherein the reflecting means is a convex reflecting plate.   The image forming apparatus according to claim 7, wherein the reflecting plate is formed of a resin film material on which a metal thin film is formed.   The image forming apparatus according to claim 7, wherein the reflector is made of a metal material.   The image forming apparatus according to claim 1, wherein a plurality of the image carriers are arranged, and the charge eliminating exposure unit is provided for each of the image carriers.

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