JP2016212365A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an increase in size of an apparatus while ensuring the intensity of radiation light from light irradiation means.SOLUTION: An image forming apparatus comprises: a rotatable image carrier 10 that includes a photosensitive layer on a surface 10a; a transfer member 14 that forms a transfer position N at which a visible image formed on the surface of the image carrier is transferred to a recording material P; a cleaning blade 15 that forms a cleaning position B1 at which attachments X and X1 attached to the surface of the image carrier after the transfer at the transfer position are removed; and light irradiation means 26 that irradiates the surface of the image carrier located between the transfer position and the cleaning position with light. The light irradiation means is arranged on a side of the back face Pb of the recording material P across a conveyance path with respect to the surface of the image carrier, and a member 32 having light transmissivity is arranged between the light irradiation means and a photoreceptor.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus.

  In an electrophotographic image forming apparatus, an electrostatic latent image is formed on the surface of an image carrier provided with a photosensitive layer, the electrostatic latent image is developed with a charged developer, and an image is formed on a recording material at a transfer position. Is being transcribed. In such a configuration, deposits such as transfer residual toner and paper dust generated on the surface of the image carrier are cleaned by providing a cleaning member. If the bonding force is strong, it causes a cleaning failure. Therefore, by irradiating the image carrier provided with the photosensitive layer with light from the light irradiation means before cleaning, the surface potential of the image carrier is reduced and the adhesion between the image carrier and the deposit is weakened. It has been proposed (for example, Patent Document 1).

In the configuration of Patent Document 1, light is applied to the surface of the image carrier by irradiating the image carrier with light to weaken the adhesion to the deposit. However, floating toner is used as a light source of the light irradiating means for irradiating light. If attached, the cover member is required because the amount of light applied to the image carrier is reduced. However, simply disposing the cover member between the light source and the image carrier leads to an increase in the size of the apparatus.
An object of the present invention is to propose a configuration capable of suppressing the enlargement of the apparatus while securing the amount of light irradiated from the light irradiation means.

  In order to achieve the above object, an image forming apparatus according to the present invention transports a rotatable image carrier having a photosensitive layer on the surface and a visible image formed on the surface of the image carrier through a conveyance path. A transfer member for forming a transfer position to be transferred to the recording material, a cleaning member for forming a cleaning position for cleaning deposits adhering to the surface of the image carrier after transfer at the transfer position, and a transfer position. A light irradiating means for irradiating light on the surface of the image carrier positioned between the cleaning position and the light irradiating means is disposed on the back side of the recording material across the transport path with respect to the surface of the image carrier. In addition, a light transmissive member is disposed between the light irradiation means and the photosensitive member.

  According to the present invention, the light irradiating means for irradiating the surface of the image carrier positioned between the transfer position and the cleaning position has the back side of the recording material across the conveyance path with respect to the surface of the image carrier. Since the light transmissive member is disposed between the light irradiating means and the photosensitive member, the scattered toner does not easily adhere to the light irradiating means, and the amount of light emitted from the light irradiating means is secured. Also, an increase in the size of the apparatus can be suppressed.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. The enlarged view which shows the structure of the principal part which concerns on the 1st Embodiment of this invention. The figure which shows arrangement | positioning and schematic structure of a light irradiation means. The perspective view which shows the structure of the member which has a light transmittance provided with a light irradiation means. FIG. 2 is a block diagram illustrating a configuration of a control system of the image forming apparatus illustrated in FIG. 1. The timing chart which shows the light emission timing of the light irradiation means by the control part which concerns on the 2nd Embodiment of this invention. The timing chart which shows the light emission timing of the light irradiation means by the control part which concerns on the 3rd Embodiment of this invention. The timing chart which shows the light emission timing of the light irradiation means by the control part which concerns on the 4th Embodiment of this invention. The figure which shows the characteristic of the output control of the light irradiation means by the control part which concerns on the 5th Embodiment of this invention. The figure which shows the characteristic of the output control of the light irradiation means by the control part which concerns on the 6th Embodiment of this invention. The figure which shows the characteristic of the output control of the light irradiation means by the control part which concerns on the 7th Embodiment of this invention. The figure which shows transition of the rank of the black stripe which generate | occur | produces on a recording material. The enlarged view which shows the structure of the principal part which concerns on the 8th Embodiment of this invention. The enlarged view which shows the structure of a comparative example. (A)-(c) is a figure which shows the characteristic of the output control of the light irradiation means by the control part which concerns on the 9th Embodiment of this invention. The figure which shows the characteristic of another example of the output control of the light irradiation means by the control part which concerns on 9th Embodiment. The schematic block diagram which shows the structure of the principal part which concerns on the 10th Embodiment of this invention. (A)-(c) is a figure which shows the characteristic of the output control of the isolation | separation bias output means by the control part which concerns on the 10th Embodiment of this invention. The figure which shows the characteristic of another example of the output control of the isolation | separation bias output means by the control part which concerns on 10th Embodiment. The figure which shows an example of the electrification row | line | column of the material used for a guide member. The enlarged view which shows the structure of the principal part which concerns on the 11th Embodiment of this invention. (A) is an enlarged view explaining arrangement | positioning of the shielding member which concerns on the 11th Embodiment of this invention, (b) is an enlarged view explaining the subject in case there is no shielding member. FIG. 3 is a schematic configuration diagram showing another embodiment of the image forming apparatus according to the present invention.

  Hereinafter, a plurality of embodiments according to the present invention will be described with reference to the drawings. The image forming apparatus according to the present invention reduces the potential of the image carrier by irradiating the surface of the image carrier with light from the light irradiation unit before the cleaning process on the image carrier having the photosensitive layer. It is intended to reduce the adhesion force between the deposit adhered to the carrier and the image carrier. In each embodiment, components having the same functions and configurations are denoted by the same reference numerals, and redundant description will be omitted as appropriate. The drawings may be partially omitted to facilitate understanding of the configuration.

  A copying machine 1 as an image forming apparatus according to the present embodiment shown in FIG. 1 includes a scanner device 2 as an image reading device, and a printer that forms an image of a document read by the scanner device 2 on a sheet-like recording material P. The apparatus 3 is provided. In the printer device 3, a tray 4 as a paper feeding unit for stacking and holding recording materials P, or a manual feed tray 5 for receiving the manual recording material P, an image forming unit 6 as a printer engine, a fixing device 7, and optical writing A device 12 is arranged. A space is formed between the scanner device 2 and the printer device 3. A stack portion 8 on which the recording material P is discharged and stacked is formed on the upper portion of the printer device 3 located in this space. An upstream transport path 9A is formed from the tray 4 or the manual feed tray 5 to the image forming unit 6, and a downstream transport path 9B is formed from the image forming unit 6 to the fixing device 7. The recording material P is transported in the upstream transport path 9A and the downstream transport path 9B. In the drawing, the arrow A indicates the conveyance direction of the recording material P (hereinafter referred to as “recording material conveyance direction A”).

As shown in FIG. 2, the image forming unit 6 includes a drum-shaped photoreceptor 10 as an image carrier having a photosensitive layer on the surface 10a. The photoconductor 10 is supported by, for example, a side plate of the printer device 3 so as to be able to rotate in a counterclockwise direction (hereinafter referred to as “photoconductor rotation direction B”) in the drawing. The photoconductor 10 is rotationally driven in the photoconductor rotation direction B by a drive motor 40 as a drive source shown in FIG. Around the photoconductor 10, in accordance with an electrophotographic process, a charging roller 11 as a charging member, an irradiation exposure position B1 of writing light L by an optical writing device 12 (see FIG. 1), a developing device 13, and a transfer roller as a transfer member 14, a cleaning blade 15 as a cleaning member and the like are sequentially arranged.
The optical writing device 12 shown in FIG. 1 uses the laser light emitted from the laser diode based on the image data of the original read by the scanner device 2 as the writing light L, and the surface 10a of the photosensitive member 10 (hereinafter referred to as “photosensitive member surface 10a”). And is optically scanned. By this optical scanning, an electrostatic latent image is formed on the photoreceptor surface 10a.

In the present embodiment, a contact transfer method in which the surface 14a of the rotatable transfer roller 14 abuts on the photoreceptor surface 10a to form a transfer nip N is employed. The transfer roller 14 is configured to be applied with a transfer bias from a transfer bias power supply 41. The transfer roller 14 serves as a transfer position for transferring a toner image, which is a visible image formed on the photoreceptor surface 10a, by applying a transfer bias to the recording material P conveyed through the upstream conveyance path 9A. A transfer nip N is formed. The transfer member may be a rotatable transfer brush instead of the transfer roller.
The developing device 13 is a developing sleeve 16 as a developer carrying member that faces the surface 10a of the photoreceptor and supplies toner as a developer to the electrostatic latent image, a toner sensor 17 as a developer concentration detecting means, and a developer conveying means. As a pair of conveying screws 13A, 13B and the like. With such a configuration of the developing device 13, the electrostatic latent image on the photoreceptor surface 10 a is developed to form a toner image. Reference numeral 18 denotes a P sensor as image density detecting means for detecting the toner density of the toner image formed on the photoreceptor surface 10a.
A registration roller pair 19 that controls the conveyance timing of the recording material P to the transfer nip N is disposed in the upstream conveyance path 9A located upstream of the transfer nip N in the recording material conveyance direction A. An upstream conveyance guide 31 is disposed between the registration roller pair 19 and the transfer roller 14.
The end of the cleaning blade 15 is in contact with the photoreceptor surface 10a, and the photoreceptor 10 rotates, so that the residual toner adhered to the photoreceptor surface 10a or the adhering matter X that is agglomerated toner, or paper It is cleaned by scraping off the deposit X1 which is powder. In this embodiment, the position where the cleaning blade 15 contacts the photoreceptor surface 10a is defined as a cleaning position B2. That is, the cleaning blade 15 forms a cleaning position B2 for cleaning the deposits X and X1 adhering to the photoreceptor surface 10a after the transfer at the transfer nip N.

  In such a configuration, the surface 11a of the charging roller 11 is in contact with the photoconductor surface 10a. When the photoconductor 10 rotates and a charging bias is applied to the charging roller 11, the surface of the photoconductor surface 10a is uniform. Charge is supplied. As a result, the photoreceptor surface 10a is uniformly charged at a constant potential. An electrostatic latent image is formed on the charged photoreceptor surface 10a by being irradiated with the writing light L from the optical writing device 12 and optically scanned. When the electrostatic latent image passes through a position facing the developing sleeve 16 of the developing device 13 as the photoconductor 10 rotates, the electrostatic latent image is developed with toner supplied from the developing sleeve 16 to become a toner image. The recording material P fed from the tray 4 or the like and fed to the transfer nip N by the registration roller pair 19 is subjected to a transfer action (transfer electric field) by the transfer roller 14 when passing through the transfer nip N. The toner image formed on the surface 10a is transferred. The recording material P to which the toner image has been transferred is conveyed to the fixing device 7 shown in FIG. 1, and the toner image is melted and fixed on the recording material P by heat and pressure. The recording material P after fixing is sequentially discharged and stacked on the stack unit 8 as an output image (a copy).

The contact transfer method employed in this embodiment will be described.
The transfer roller 14 is a contact transfer type transfer member. The resistance value of the transfer roller 14 is 10 ^ 6 to 10 ^ 9 [Omega] under a normal temperature and humidity environment of 23 [deg.] C. and 50% Rh and a DC voltage of 1000V. The transfer bias supplied from the transfer bias power supply 41 to the transfer roller 14 is subjected to constant current control. In other words, in the present embodiment, the transfer bias applied to the transfer roller 14 is adjusted so that the value of the current that flows when paper is passed (during printing) is constant. As a basic transfer characteristic, the toner image on the photoreceptor surface 10a is electrically attracted to the surface Pa of the recording material P by applying a charge having a polarity opposite to that of the toner to the back surface Pb side (back surface side) of the recording material P. Is given. The surface Pa of the recording material P is a transfer surface onto which a toner image is transferred, and is a surface facing the photoreceptor surface 10a. The back surface Pb of the recording material P is a surface located on the opposite side to the front surface Pa and is a surface that does not face the photoreceptor surface 10a.
Deposits X and deposits X1 remain on the photoreceptor surface 10a after the transfer. When the photosensitive member 10 rotates and reaches the cleaning position B2, which is a contact point with the cleaning blade 15, the adhering substances X and X1 are scraped and cleaned from the surface 10a of the photosensitive member by the cleaning blade 15. The scraped deposits X and X1 are transported toward the developing device 13 by a recovery transport screw 21 disposed in the vicinity of the cleaning blade 15, and are replenished and recycled to the developing device 13 together with new toner.

(First embodiment)
Next, a characteristic configuration and operation in the present embodiment will be described.
As shown in FIG. 2, in the downstream conveyance path 9B located downstream of the transfer nip N in the recording material conveyance direction A (downstream of the recording material conveyance direction), static elimination that is both light irradiation means and static elimination means. A light source 26 is provided. The static elimination light source 26 is light with respect to the photoreceptor surface 10a located downstream of the transfer nip N in the photoreceptor rotation direction B and between the cleaning blade 15 and upstream of the photoreceptor rotation direction B. The surface potential of the photoconductor 10 is reduced before cleaning by irradiating with the neutralizing light K. As shown in FIG. 3, the static elimination light source 26 includes a substrate 26b and a light source unit 26a arranged on the substrate 26b. The static elimination light source 26 can adjust the light emission quantity of the light source part 26a. In the present embodiment, the static elimination light source 26 uses a light emitting diode (LED) for the light source unit 26a. The light source unit 26a may be another light source such as electroluminescence (EL) instead of a light emitting diode. In short, any light source capable of obtaining a light amount for removing the charge on the photoreceptor surface 10a can be substituted.
As shown in FIG. 1, the static elimination light source 26 is disposed on the back surface Pb side of the recording material P passing through the downstream conveyance path 9B, and the static elimination light K passes through the recording material P and reaches the photoreceptor surface 10a. It is configured to be irradiated. The direction of the neutralization light source 26 is set so that the center of the optical axis is located at the rotation center of the photoconductor 10, and is arranged so that the neutralization light K is irradiated toward the rotation center of the photoconductor 10. . Reference symbol B3 indicates an irradiation position where the charge removing light K is irradiated onto the surface 10a of the photosensitive member.

As shown in FIG. 2, a downstream guide member (hereinafter referred to as “guide member”) 32 is disposed between the static elimination light source 26 and the photosensitive member 10 as a light transmissive member. The guide member 32 is a conveyance guide member that conveys and guides the recording material P passing through the conveyance path 9B on the downstream side toward the fixing device 7 (see FIG. 1), and also functions as a cover member that covers the static elimination light source 26. To do. That is, the guide member 32 is made of a transparent resin, is disposed between the light source unit 26a of the static elimination light source 26 and the photosensitive member 10, and is provided so as to cover at least the light source unit 26a, and also for recording. It is a guide member for guiding the conveyance of the material P.
In the present embodiment, the static elimination light source 26 is linearly arranged at a plurality of intervals in the width direction of the recording material P indicated by the arrow W, as shown in FIGS. The width direction W is a direction orthogonal (crossing) on the same plane as the recording material conveyance direction A. In the present embodiment, eight light source units 26a are arranged on the substrate 26b to constitute the static elimination light source 26. The static elimination light source 26 is not provided with a plurality of light source parts 26a on one substrate 26b, but may be one static elimination light source 26 with one light source part 26a provided on one substrate 26b. A plurality of static elimination light sources 26 configured independently may be arranged in the width direction W.

  The static elimination light source 26 is arranged so that the irradiation areas of the irradiation light K from the adjacent light source sections 26a overlap at the end of the irradiation area, so that the illumination intensity is substantially uniform in the irradiation area indicated by reference numeral W1. Has been adjusted. That is, the irradiation range W <b> 1 irradiated with the neutralizing light K on the photoconductor 10 is an area wider than at least the width W <b> 2 of the recording material P. In the present embodiment, the static elimination light K emitted from the static elimination light source 26 is applied to an area (effective image area) on the photoreceptor surface 10a where an image may be formed before cleaning, and the photoreceptor surface after transfer. It is possible to reduce the residual potential of 10a.

The static elimination light source 26 is disposed between the conveyance guide surface 32a of the guide member 32 and the frame 34 of the opening / closing cover so that the light source unit 26a is positioned on the conveyance guide surface 32a side. The opening / closing cover is a cover member for releasing the conveyance path by jamming or the like, and is arranged on the right side in the drawing with respect to the conveyance path 9B from the registration roller pair 19 to the fixing device 7 in FIG. The guide member 32 is positioned against the frame 34 of the opening / closing cover. In the present embodiment, the guide members 32 are all transparent, but at least the transport guide surface 32a facing the light source unit 26a only needs to be light transmissive. Further, here, the static elimination light K is transmitted through the conveyance guide surface 32a using a transparent resin so that the photosensitive member surface 10a can be irradiated. However, the light transmittance required for the guide member 32 is not necessarily limited to that obtained by making it transparent. For example, if the amount of light necessary for static elimination can be ensured, it may be translucent or colored such as red, or it may be clouded as fine irregularities formed by sandblasting etc. Also good.
In this way, as shown in FIG. 1, the irradiation position B3 for irradiating the surface 10a of the photosensitive member located between the transfer nip N as the transfer position and the cleaning position B2 is set, and the position is set. When the neutralization light K is irradiated to the photosensitive member 10, the static electricity is removed so that the residual potential on the surface 10 a of the photoreceptor is reduced. For this reason, the charging by the charging roller 11 after cleaning by the cleaning blade 15 becomes uniform, and the occurrence of afterimages can be prevented.
Further, by irradiating the neutralizing light K toward the rotation center of the photoconductor 10, it is possible to efficiently neutralize the static electricity. Even when it is not directed to the center in the layout, if the tilt angle is about ± 10 degrees, it can be sufficiently obtained as a static elimination effect.

  As shown in FIG. 2, a static elimination needle 30 as a static elimination member is disposed between the transfer roller 14 and the guide member 32, more specifically, between the transfer nip N and the static elimination light source 26. In the static elimination needle 30, a plurality of metal needles 30b are arranged on a plurality of straight lines in the width direction W as shown in FIG. The tip of the needle 30b faces the downstream conveyance path 9B, and is configured to discharge the recording material P by contacting the recording material P that has passed through the transfer nip N.

In the present embodiment, since the recording material P contacts the photoreceptor surface 10a in the transfer nip N, paper dust may adhere from the recording material P to the photoreceptor surface 10a, which may become the deposit X1. In particular, when a filler such as calcium carbonate, kaolin, or white carbon is used for the recording material P, these are likely to be the main components of paper powder. These materials that can become paper dust are easily positively charged, and are more likely to adhere electrostatically to the photoreceptor surface 10a with a stronger force than the untransferred toner remaining on the photoreceptor surface 10a. In addition, since these paper dusts have a smaller particle size than the toner, they easily pass through the cleaning position B2, which is the contact portion between the photoreceptor surface 10a and the cleaning blade 15.
However, the surface potential of the photoconductor 10 is reduced by irradiating the neutralization light K from the static elimination light source 26 to the irradiation position B3 upstream of the cleaning blade 15 in the rotational direction B of the photoconductor. The electrostatic adhesion force of the deposit X1 (paper powder) is reduced. For this reason, the deposit X1 on the surface 10a of the photoreceptor can be removed and collected by the cleaning blade 15 and a good copy with no vertical stripes can be obtained.

As described above, the intensity (light emission amount) of the neutralizing light K applied to the photoreceptor surface 10a which is the photosensitive layer of the photoreceptor 10 before the cleaning process by the cleaning blade 15 decreases the surface potential of the photoreceptor 10 to near zero. Even if not, if the surface potential of the photoconductor 10 can be reduced to some extent, the above-described effects can be sufficiently exhibited.
For this reason, the static elimination light source 26 is arranged on the back surface Pb side of the recording material P, and the electrostatic adhesion force of the deposit X1 to the photosensitive member surface 10a even with the amount of light that passes through the recording material P and is irradiated to the photosensitive member surface 10a. Can be reduced. As a result, it is possible to prevent the deposit X1 from slipping through the cleaning blade 15 at the cleaning position B2.

In general, when a toner charge amount is reduced, such as in a high temperature and high humidity environment, a small amount of toner may be scattered in the copying machine 1. Such scattered toner has a charge amount lower than usual, but has a charge, and may adhere to the light source portion 26 a of the static elimination light source 26.
However, in this embodiment, since the light-transmissive guide member 32 is disposed between the photoconductor 10 and the static elimination light source 26, it is possible to reduce or prevent the scattered toner from adhering to the light source unit 26a. it can. The material of the guide member 32 may be glass or the like in addition to the resin, but it is necessary to have transparency to obtain a light amount for removing the charge from the photoreceptor 10.
As shown in FIG. 1, the guide member 32 also serves as a conveyance guide member that guides the recording material P from the transfer nip N (transfer position) to the fixing device 7. Since the amount of scattered toner is very small and does not concentrate and adhere to the transparent guide member 32, there is no problem that the static elimination light K is blocked even over time and the static elimination effect cannot be obtained. Further, since the recording material P comes into contact with the conveyance guide surface 32a of the guide member 32, a cleaning effect of scattered toner due to the contact of the recording material P with the conveyance guide surface 32a can be expected. For this reason, while ensuring the amount of light emitted from the static elimination light source 26, disposing the apparatus on the back surface Pb side of the recording material P with respect to the downstream conveyance path 9B having a relatively large margin can suppress the increase in size of the apparatus. A possible configuration.

Here, it is also conceivable to provide a structure in which the static elimination light source 26 is covered with a light transmissive member on the same side as the photoreceptor 10 (the surface Pa side of the recording material P). However, in order to arrange the two members of the static elimination light source 26 and the light transmissive member, an installation space is required around the photosensitive member (on the surface Pa side of the recording material P), and the apparatus (printer) is large. turn into. Further, around the photosensitive member (the surface Pa side of the recording material P), the toner on the surface of the light transmissive member from the photosensitive member 10 is likely to scatter from the back surface Pb of the recording material P. There is also a possibility that the static elimination light K from the light source 26 may be blocked.
However, if the static elimination light source 26 is arranged on the back surface Pb side of the recording material P as in the present embodiment, compared to the case where it is arranged on the front surface Pa of the recording material P, the back surface Pb side in the downstream transport path 9b is arranged. Since the space can be used, the enlargement of the apparatus (copier 1) can be prevented. Further, the toner scattered from the photosensitive member 10 side when the recording material P is passed can be blocked by the recording material P itself, and the guide member 32 which is a light-transmitting member is relatively separated from the photosensitive member surface 10a. It is arranged at a distant position. For this reason, since the amount of scattered toner adhering to the conveyance guide surface 32a which is the surface of the guide member 32 can be reduced, it is preferable because the amount of light emitted from the static elimination light source 26 can be easily secured.
That is, the scattered toner is less likely to adhere to the static elimination light source 26, and an increase in the size of the apparatus can be suppressed while securing the amount of light emitted from the static elimination light source 26.

In the present embodiment, the conveyance guide surface 32a has at least a portion facing the light source part 26a of the static elimination light source 26 as a flat surface. This is to prevent the static electricity K from diffusing. In the present embodiment, as shown in FIG. 4, the entire conveyance guide surface 32a is formed as a flat surface in the width direction W, and the plurality of ribs 33 are shifted in the width direction by shifting in the recording material conveyance direction A with respect to the conveyance guide surface 32a. There are a number of W. For this reason, the transportability of the recording material P can be ensured by the ribs 33 while suppressing a reduction in the amount of light due to the diffusion of the static elimination light K from the static elimination light source 26.
Of course, a plurality of ribs 33 may be arranged on the transport guide surface 32a in the width direction W to improve the transportability of the recording material P. Even in this case, the rib 33 is not formed in the portion facing the light source part 26a, thereby suppressing the reduction in the amount of light due to the transportability of the recording material P and the diffusion of the charge removal light K from the charge removal light source 26. This is a preferable configuration.

Next, control of the light emission timing of the static elimination light source 26 will be described.
FIG. 5 is a block diagram showing a schematic configuration of a control system of the copying machine 1. The copying machine 1 includes a control unit 100. The control unit 100 includes a CPU (Central Processing Unit) 101 as a calculation means, a ROM (Read Only Memory) 102 as a nonvolatile memory, and a RAM (Random Access Memory) 103 as a temporary storage means. Various components and sensors are communicably connected via a signal line to the control unit 100 that controls the entire copying machine. FIG. 5 relates to the characteristic configuration of the embodiment. Only the equipment is shown. In FIG. 5, the configuration and sensors used in each embodiment are shown together, and description will be made assuming that they function as the control unit 100 of each embodiment.

On the input side of the control unit 100, a recording material position detection sensor 45 as a recording material position detection means, a photosensitive member speed detection sensor 46 as a rotation speed detection means, a blade distance detection sensor 47 as a usage rate detection means, and environmental conditions A temperature / humidity detection sensor 48 as a detecting means is connected via a signal line.
On the output side of the control unit 100, there are a driving motor 40 for the photoconductor, a transfer bias power source 41, a driving unit 42 of the optical writing device 12, a driving unit 43 of the static elimination light source 26, and a driving unit 44 of the static elimination light source 25 described later. A separation bias applying unit 49 is connected via a signal line.

The recording material position detection sensor 45 detects the position of the recording material P during printing. For example, the recording material position detection sensor 45 is disposed in the vicinity of the registration roller pair 19 and outputs an ON signal while detecting the recording material P. It is a sensor.
The photoconductor speed detection sensor 46 detects the rotation speed of the photoconductor 10 and outputs rotation speed information.
The blade distance detection sensor 47 detects the usage rate (use period) of the cleaning blade 15. The blade distance detection sensor 47 detects a parameter that correlates with the usage rate, such as the number of rotations of the photosensitive member 10 and the number of sheets passed, and detects a distance at which the rotating photosensitive member 10 and the cleaning blade 15 are in contact with each other. To calculate. For example, the circumferential length of the photosensitive member 10 is obtained in advance, and a table indicating how many kilometers the photosensitive member 10 is rotated 1000 times is created and stored in the ROM 102. The number of rotations of the photoconductor 10 may be regarded as one rotation when, for example, one recording material P is passed. The number of sheets of the recording material P1 may be counted with a counter or the like.
The temperature / humidity detection sensor 48 detects the temperature and humidity in the copying machine 1 and detects temperature and humidity which are one of the environmental conditions. The temperature and humidity detected by the temperature / humidity detection sensor 48 may be those in the room where the copying machine 1 is installed. That is, the temperature / humidity detection sensor 48 detects the temperature and humidity inside and outside the apparatus.
The control unit 100 performs on / off control of the operation of the drive unit 43 of the static elimination light source 26 according to the detection information from each of these sensors, and sets the emission timing (irradiation timing) of the static elimination light K emitted from the static elimination light source 26. Control. The control unit 100 controls the rotation speed (linear speed) of the photoconductor 10 by controlling the operation of the drive motor 40 for the photoconductor. The controller 100 controls the operation of the transfer bias power supply 41 to control the output and output timing of the transfer bias. The control unit 100 controls the drive unit 42 of the optical writing device 12 to control the irradiation timing of the writing light, and determines the print start time from the ON signal of the drive unit 42.

(Second Embodiment)
In the present embodiment, the light emission timing of the static elimination light source 26 is controlled by the control unit 100 shown in FIG. FIG. 6 is a timing chart according to the second embodiment of the light emission timing (turned on / off) of the static elimination light source 26 in synchronization with the operation timing of the drive motor 40 for the photosensitive member.
That is, in this embodiment, when the drive motor 40 is operated, the drive unit 43 of the static elimination light source 26 is turned on by the control unit 100, the light source unit 26a is caused to emit light, and the static elimination light K is emitted toward the photoreceptor surface 10a. To do. In this embodiment, when the operation of the drive motor 40 is stopped, the drive unit 43 is controlled to be turned off by the control unit 100 so that the light emission of the light source unit 26a is stopped and the irradiation of the charge removal light K is stopped.
When such control is executed, the static elimination light source 26 is turned on only when the photoconductor 10 rotates, so that the photoconductor 10 is less fatigued than when the static elimination light K is irradiated until non-image formation. Can be reduced. That is, when the surface 10a of the photosensitive member 10 is irradiated with the static elimination light K when the rotation of the photosensitive member 10 is stopped, the light fatigue progresses with respect to time, so that the deterioration of the photosensitive layer of the photosensitive member 10 is accelerated. However, by performing the light emission timing control as in the present embodiment, the durability of the photoconductor 10 is improved while ensuring the amount of light emitted from the static elimination light source 26.

(Third embodiment)
In the second embodiment, the adhesion force of the deposit X1 (paper dust) to the photoreceptor 10 is reduced by removing the charge on the photoreceptor surface 10a through the recording material P. However, when the recording material P is not present between the photosensitive member 10 and the neutralization light source 26, the amount of attachment X1 on the photosensitive member 10 is less than that when the recording material P is interposed in the transfer nip N. It tends to be small.
Therefore, in the third embodiment, as shown in FIG. 7, the light emission timing of the static elimination light source 26 is controlled by the control unit 100 so as to be synchronized with the timing of applying the transfer bias to the transfer roller 14.
That is, in synchronization with a transfer bias that is a transfer output at a transfer nip N (see FIG. 1) that is a transfer position, the light source 26a of the static elimination light source 26 emits light and the static elimination light K is emitted. In the interval between sheets, the light emission of the photoconductor 10 is suppressed by turning off the light emission of the light source unit 26a of the static elimination light source 26. The control unit 100 determines the conveyance position of the recording material P based on whether or not the recording material position detection sensor 45 outputs (ON signal). That is, when the recording material position detection sensor 45 detects the recording material P and a detection signal (ON signal) is output, the control unit 100 illustrated in FIG. 5 drives the driving unit 43 of the static elimination light source 26 to be on. Then, the light source unit 26a of the static elimination light source 26 is caused to emit light. When there is no detection signal from the recording material position detection sensor 45, the control unit 100 turns off the drive unit 43, stops the light source unit 26a of the static elimination light source 26, and stops the irradiation of the static elimination light K.

  As shown in FIG. 2, the transfer nip N and the irradiation position B <b> 3 of the charge removal light K are slightly shifted in the photosensitive member rotation direction B. However, in this embodiment, as shown in FIG. 7, the transfer bias power supply 41 is turned on by the control unit 100 slightly before the recording material P reaches the transfer nip N, and the recording material P passes through the transfer nip N. It is controlled to turn off after a while. For this reason, the static elimination light K can be applied to the photoreceptor surface 10a through the recording material P while the recording material P passes through the downstream conveyance path 9B. It can suppress compared with 2nd Embodiment.

(Fourth embodiment)
In the present embodiment, in order to obtain a more efficient and effective effect, the control unit 100 performs output control (emission amount control) of the static elimination light source 26. The deposit X1 adhering to the photoreceptor 10 tends to be large at the position where the recording material P is interposed in the transfer nip N. However, when the deposit X1 adhering to the transfer roller 14 moves to the photoreceptor 10 between papers, the deposit X1 (paper dust) mixed in the recycled toner from the developing device 13 is also developed together with the toner during development. There is a case. For this reason, slight adhesion of the deposit X1 to the photoreceptor 10 is confirmed even between the sheets. However, since the static elimination light K passes through the recording material P and is applied to the surface 10a of the photoreceptor, the amount of light (irradiation amount) to the photoreceptor 10 changes depending on whether the sheet is passing or when the image is formed. To do.

Therefore, in the present embodiment, as shown in FIG. 8, the light emission amount of the light source unit 26 a of the static elimination light source 26 is controlled by the control unit 100. Specifically, the light emission amount of the light source unit 26 a of the static elimination light source 26 is controlled by the control unit 100 according to the conveyance timing of the recording material P. That is, the control unit 100 emits a large amount of light when the recording material P is transported through the downstream transport path 9B, and weakens when the recording material P is not transported through the downstream transport path 9B. The static elimination light source 26 is controlled so that it becomes. The control unit 100 determines whether or not the recording material P is being passed and the interval between the recording materials P based on the presence or absence of an ON signal from the recording material position detection sensor 45.
That is, in this embodiment, the light emission timing and the light amount of the static elimination light source 26 are appropriately controlled so that the light emission amount is strong when the recording material P is interposed in the transfer nip N, and between the papers where the recording material P is not interposed. The amount of light emitted from the static elimination light source 26 is controlled by the control unit 100 so that the amount of emitted light is reduced and the amount of irradiated light becomes weak (the output decreases). However, the amount of irradiation light when the output is reduced is such that the amount of light that reduces the electrostatic adhesive force between the deposit X1 (paper dust) and the photosensitive member 10 is secured. As a result, it is possible to prevent the cleaning blade 15 from slipping through the cleaning position B2 (see FIG. 2) of the deposit X1 (paper dust) while suppressing the light fatigue of the photoconductor 10, thereby maintaining the image quality. It is possible.

(Fifth embodiment)
In the present embodiment, the control unit 100 adjusts and controls the light amount of the static elimination light K from the static elimination light source 26 in accordance with the rotational speed (linear velocity) of the photoconductor 10.
The amount of light applied to the photoconductor 10 for reducing the electrostatic adhesion force between the deposit X1 (paper dust) and the photoconductor 10 also varies depending on the linear velocity that is the rotational speed of the photoconductor 10. When the linear velocity of the photoconductor 10 is increased (increased), the irradiation time per unit time is shortened, and therefore, it is necessary to increase (increase) the amount of discharge light K emitted from the charge removal light source 26. The copying machine 1 according to the present embodiment has a low speed mode in which the linear speed of the photoconductor 10 is slower than the normal mode in order to reduce noise and a high image, and a mode in which the linear speed is adjusted according to the paper type. doing. For this reason, as shown in FIG. 9, the control unit 100 adjusts and controls the light amount (output) of the static elimination light source 26 for each linear velocity, thereby making it possible to adjust the balance between the light fatigue of the photoreceptor 10 and the cleaning performance of the deposit X1. Has been.

That is, the ROM 102 of the control unit 100 shown in FIG. 5 stores data defining the relationship between the linear velocity of the photoconductor 10 detected by the photoconductor speed detection sensor 46 and the output of the static elimination light K emitted from the static elimination light source 26. A table is stored in advance. This table is set so that the irradiation amount as the output of the static elimination light source 26 increases as the linear velocity of the photosensitive member 10 increases. In other words, when the fully open output of the light source unit 26a of the static elimination light source 26 is set to 100%, the output ratio (%) is set to be higher as the linear velocity of the photoconductor 10 becomes faster. Further, the output of the static elimination light source 26 with respect to these linear velocities may sufficiently reduce the adhesion force of the deposit X1 (paper dust) electrostatically adhering to the photoreceptor surface 10a rotating at the linear speed. It is a possible output value (irradiation light quantity).
That is, the control unit 100 increases the light emission amount (irradiation light amount) when the rotation speed detected by the photoconductor speed detection sensor 46 is high, and decreases the light emission amount (irradiation light amount) when the rotation speed is low. The static elimination light source 26 is controlled.
For this reason, even when the linear velocity of the photoconductor 10 changes, it is possible to irradiate the photoconductor surface 10a with a light amount of the static elimination light K corresponding thereto. Therefore, the adhesion force of the deposit X1 (paper dust) can be sufficiently reduced, and it is possible to prevent slipping at the cleaning position B2 (see FIG. 2) and maintain the image quality.

(Sixth embodiment)
In the present embodiment, the control unit 100 adjusts and controls the light amount of the static elimination light K from the static elimination light source 26 in accordance with the usage frequency of the cleaning blade 15. In this embodiment, since the cleaning blade 15 uses a urethane rubber blade, the cleaning blade 15 is worn by sliding contact with the photoreceptor surface 10a, and the cleaning performance tends to be lower than the initial one over time.
For this reason, in this embodiment, as shown in FIG. 10, the control unit 100 adjusts and controls the amount of light that is the output of the static elimination light source 26 in accordance with the usage rate (travel distance in the drawing) of the cleaning blade 15. Yes. That is, the ROM 102 of the control unit 100 shown in FIG. 5 shows the relationship between the travel distance that is the usage rate of the cleaning blade 15 detected by the blade distance detection sensor 47 and the output of the static elimination light K emitted from the static elimination light source 26. A prescribed data table is stored in advance. This data table is set so that the light emission amount of the light source unit 26a of the static elimination light source 26 is increased and the irradiation light amount as an output is increased as the use distance of the cleaning blade 15 becomes longer. That is, when the output of the light source 26a of the static elimination light source 26 is 100%, the output ratio (%) is set higher as the use distance (travel distance) of the cleaning blade 15 becomes longer. Further, the output of the static elimination light source 26 with respect to the use distance of the cleaning blade 15 indicates that the deposit X1 (paper dust) electrostatically attached to the photosensitive member surface 10a during cleaning by the cleaning blade 15 that has reached the use distance. This is an output value (irradiation light amount) that can sufficiently reduce the adhesive force. That is, in the present embodiment, the control unit 100 controls the static elimination light source 26 so that the light emission amount increases as the usage rate detected by the blade distance detection sensor 47 increases.
For this reason, it is possible to prevent the slippage of the deposit X1 (paper dust) at the cleaning position B2 (see FIG. 2) between the cleaning blade 15 and the photosensitive member surface 10a and maintain the image quality. .

(Seventh embodiment)
In the present embodiment, the control unit 100 adjusts and controls the output of the static elimination light K from the static elimination light source 26 in accordance with temperature and humidity information which is one of the environmental conditions of the copying machine 1.
As described above, the adhering matter X1, which is paper dust among the adhering matters, often has a weak positive charge, but the charge amount may change depending on the temperature and humidity. In general, the charge amount tends to increase as the humidity decreases, and the attached material X1 may easily slip through at the cleaning position B2 (see FIG. 2) between the cleaning blade 15 and the photoreceptor surface 10a.
For this reason, in the present embodiment, a temperature / humidity detection sensor 48 (see FIG. 5) is provided as an environmental condition detection means, and the light source unit of the static elimination light source 26 according to the detection value of the temperature / humidity detection sensor 48 as shown in FIG. The control unit 100 adjusts and controls the light emission amount 26a. In the present embodiment, the absolute humidity is obtained from the detection value of the temperature / humidity detection sensor 48, and the light amount is adjusted according to the absolute humidity.

  That is, the ROM 102 of the control unit 100 shown in FIG. 5 shows the relationship between the absolute humidity obtained from the temperature / humidity information, which is the environmental condition detected by the temperature / humidity detection sensor 48, and the output of the static elimination light K of the static elimination light source 26. A prescribed data table is stored in advance. This data table is set so that the irradiation light quantity, which is the output of the static elimination light source 26, is gradually reduced as the absolute humidity increases. That is, when the fully open output of the light source unit 26a of the static elimination light source 26 is 100%, the output ratio (%) is set to decrease stepwise as the absolute humidity increases. Further, the output of the static elimination light source 26 with respect to the absolute humidity can sufficiently reduce the adhesion force of the deposit X1 (paper dust) that adheres electrostatically to the photoreceptor surface 10a when the absolute humidity is concerned. It is an output value (irradiation light quantity).

That is, in the present embodiment, the control unit 100 controls the light emission amount of the static elimination light source 26 based on the detection result of the temperature / humidity detection sensor 48. Specifically, the light emission amount of the static elimination light source 26 is controlled so that the light emission amount gradually decreases as the absolute humidity obtained from the detection value of the temperature / humidity detection sensor 48 increases.
For this reason, even when the environmental conditions of the copying machine 1 change, the output (irradiation light amount) of the static elimination light K irradiated from the static elimination light source 26 to the photoreceptor surface 10a is also increased / decreased by the control unit 100 accordingly. For this reason, even when environmental conditions change, it is possible to prevent slipping of the deposit X1 (paper dust) at the cleaning position B2 between the cleaning blade 15 and the photoreceptor surface 10a, thereby maintaining the image quality. .

(Eighth embodiment)
In the first to seventh embodiments, as shown in FIG. 2, using the static elimination light source 26, the static elimination light K is applied to the photoreceptor surface 10 a located between the transfer nip N and the cleaning position B <b> 2 by the cleaning blade 15. Irradiating. For this reason, an irradiation location is one location of irradiation position B3, and is a low-cost structure. In normal use, there is no problem with the configuration shown in FIG. 2, but an afterimage may occur because the surface potential of the photoreceptor 10 before charging by the charging roller 11 is not uniform. For this reason, in order to obtain higher image quality, it is desirable to perform static elimination again after cleaning by the cleaning blade 15.
Therefore, in the present embodiment, as shown in FIG. 13, a static elimination light source 25 as a static elimination means for irradiating the photosensitive member surface 10 a located between the cleaning blade 15 and the charging roller 11 with the static elimination light Q is used as a static elimination light source. 26. As shown in FIG. 5, the driving light source 44 of the static elimination light source 25 is connected to the output side of the control unit 100 via a signal line, and its on / off operation is controlled by the control unit 100. In the case of this configuration, the static elimination light Q is applied to the photoreceptor surface 10 a after being neutralized by the static elimination light source 26 and cleaned by the cleaning blade 15. As the light emission timing of the static elimination light source 25, for example, while the drive motor 40 of the photoconductor 10 is in operation, the control unit 100 operates the drive unit 43 of the static elimination light source 26 and the drive unit 44 of the static elimination light source 25 ( The photosensitive member surface 10a is irradiated with the static elimination light K and the static elimination light Q (see FIG. 6).

In other words, in the present embodiment, the static elimination light source 25 is disposed between the cleaning blade 15 and the charging roller 11 and irradiates the photoreceptor surface 10a located between these two members with the static elimination light Q, thereby providing the photoreceptor surface. The neutralizing means for neutralizing the residual potential of 10a is configured.
According to such a configuration, the surface of the photosensitive member 10a can be uniformly discharged without the adhering matter X such as the transfer residual toner and the agglomerated toner after the cleaning by the cleaning blade 15 and the adhering matter X1. For this reason, the surface potential of the photoreceptor 10 after being charged by the charging roller 11 can be made uniform, and the image quality can be further improved.

  FIG. 6 shows the results of examining the black streak occurrence frequency when the light emission timing of the static elimination light source 26 is the embodiment shown in FIG. 6 according to the configuration shown in FIG. 13 of the present embodiment and the configuration of the comparative example shown in FIG. 12 shows. The conditions shown in FIG. 12 are examined in advance for conditions (paper type with a large amount of calcium carbonate, image area ratio) that the deposit X1 (paper dust) easily passes through at the cleaning position B2 shown in FIGS. It was set as the conditions which generate | occur | produce easily. FIG. 12 shows the result of determination based on the unique rank of black streak occurrence rank with respect to the number of output images after the copying machine 1 is operated. The black streak rank is worst, 1 is not generated, 5 is not generated, and rank 4 is generated but hardly noticeable. As shown in FIG. 14, the configuration of the comparative example is a configuration including only the static elimination light source 25 without the static elimination light source 26.

According to the determination result of the determination rank, in the comparative example (configuration of FIG. 14), black streaks gradually start to occur as the number of sheets passed, and tend to deteriorate with time, and after the occurrence, it appears to occur continuously. It has become. On the other hand, in the configuration of the present embodiment shown in FIG. 13, even if the number of sheets to be passed increases, the image determination result has a rank 4 or higher as a target value, and black streaks can be prevented from occurring from the beginning. You can see that
For this reason, not only the static elimination light K is emitted from the static elimination light source 26 to the photosensitive member surface 10a before cleaning by the cleaning blade 15, but also the static elimination light Q is emitted from the static elimination light source 25 to the photosensitive member surface 10a after the cleaning portion. Thus, the apparatus configuration is strong against black streak generation (suppressing black streak generation), and the image quality can be further improved.

(Ninth embodiment)
As shown in FIG. 3, at the leading end portion Pc of the recording material P located on the recording material conveyance direction A side and the rear end portion Pd of the recording material P located on the opposite side to the leading end portion Pc, the recording material P is exposed to the photosensitive member. The paper powder tends to move to 10. This is because the recording material P mechanically moves to the photoconductor 10 when the recording material P hits the photoconductor 10 at the front end portion Pc, and the peeling discharge when the recording material P peels from the photoconductor 10 at the rear end portion Pd. This is considered to be due to the fact that paper dust is likely to adhere to the photoreceptor 10 electrostatically. In such a case, the deposit X1 on the photoconductor 10 increases, and a part thereof may pass through the cleaning position B2 where the cleaning blade 15 and the photoconductor 10 are in contact with each other.
In such a case, it is possible to increase the margin for slipping of the cleaning blade 15 (at the cleaning position B2) by increasing the charge removal light K from the charge removal light source 26. However, intensifying the static elimination light K leads to light fatigue of the photoreceptor 10 and may lead to a decrease in durability.

Therefore, in the present embodiment, the static elimination light K is increased only when the paper dust easily adheres to the photoreceptor 10. That is, in the present embodiment, as shown in FIG. 15, using the control unit 100 shown in FIG. 5, the amount of light emitted from the static elimination light source 26 can be a time when paper dust can easily adhere to the photoreceptor 10. The static elimination light source 26 is controlled so that either one or both of the front end portion Pc and the rear end portion Pd of P is stronger than the light emission amount with respect to the central portion Pd of the recording material P. FIG. 15A shows a form in which the amount of discharge light K at the leading end Pc and the trailing end Pd of the recording material P is stronger than that at the central portion Pe. FIG. 15B shows a form in which the light emission amount of the neutralizing light K at the rear end portion Pd of the recording material P is stronger than that at the central portion Pe. FIG. 15C shows a form in which the light emission amount of the static elimination light K at the leading end portion Pc of the recording material P is stronger than that at the central portion Pe.
As described above, when the leading end portion Pc and the trailing end portion Pd of the recording material P or both pass through the transfer nip N, the output (irradiation light amount) of the discharging light K irradiated from the discharging light source 26 to the photosensitive member surface 10a is expressed as follows: The control unit 100 makes it stronger than the central part Pe. Then, while suppressing light fatigue of the photoconductor 10, it is possible to prevent slipping of the deposit X1 (paper dust) at the cleaning position B2 between the cleaning blade 15 and the photoconductor surface 10a, thereby maintaining image quality. Is possible.

FIG. 16 is a modification of the ninth embodiment. In this example, when both the front end portion Pc and the rear end portion Pd of the recording material P pass through the transfer nip N, the output (irradiation light amount) of the discharge light K irradiated from the charge removal light source 26 to the photoreceptor surface 10a is obtained. The control unit 100 makes each stronger than the central part Pe. In this case, the output of the neutralizing light K is performed before the leading end Pc of the recording material P reaches the transfer nip N, and is continued until the trailing end Pd passes through the transfer nip N. Be controlled. Further, as in the fourth embodiment shown in FIG. 8, the light emission timing and the light amount of the static elimination light source 26 are appropriately controlled so that the light emission amount is strong when the recording material P is interposed in the transfer nip N, The amount of light emitted from the static elimination light source 26 is controlled by the control unit 100 so that the amount of emitted light is reduced and the amount of emitted light is reduced (the output is reduced) between the sheets without the recording material P interposed.
With such a configuration, it is possible to more reliably prevent slippage of the deposit X1 (paper dust) at the cleaning position B2 between the cleaning blade 15 and the photoreceptor surface 10a while suppressing light fatigue of the photoreceptor 10. Image quality can be maintained. Further, the output of the neutralizing light K to the front end portion Pc of the recording material P is performed before the front end portion Pc reaches the transfer nip N, and the output of the neutralizing light K to the rear end portion Pd of the recording material P is the rear end. This is performed even when the portion Pd passes through the transfer nip N. For this reason, even if the conveyance speed of the recording material P fluctuates, it is possible to reliably irradiate the leading end portion Pc and the trailing end portion Pd with the static elimination light K that is stronger than the light emission amount with respect to the central portion Pd. It is possible to suppress light fatigue.

(Tenth embodiment)
As described above, the light transmissive guide member 32 can prevent the neutralization light source 26 from being contaminated. However, the neutralization light reaching the photoconductor 10 due to contamination of the guide member 32 over time due to toner scattering. There is a concern that the amount of K light may decrease. As already described with reference to FIGS. 3 and 4, the guide member 32 is cleaned by the recording material P coming into contact with the conveyance guide surface 32 a, which is a portion facing the light source part 26 a of the guide member 32. In addition, the recording material P on the cleaning side is also contaminated at a level that cannot be recognized by the eyes because it is cleaned from a time when the toner adhesion amount is small, and does not cause a problem in use.
However, depending on the type of the recording material P, there is a possibility that it does not come into contact with the conveyance guide surface 32a of the guide member 32, and there is a concern about insufficient cleaning. When toner accumulates on the guide member 32, the conveyance behavior of the recording material P changes due to a decrease in the amount of light on the photoconductor 10, switching to a different paper type, or curling due to fixing during double-sided printing, and the recording material P becomes dirty. The recording material P is contaminated with toner.

Therefore, in this embodiment, as shown in FIG. 17, the recording material P is actively guided in the direction of the guide member 32 by applying a separation bias to the static elimination needle 30, and the conveyance guide surface of the guide member 32 is stably provided. The recording material P is brought into contact with the recording medium 32a to stabilize the cleaning property by the recording material P, so that toner does not accumulate on the conveyance guide surface 32a (guide member).
However, if the separation bias is increased, the transfer current leaks to the static elimination needle 30 disposed near the transfer nip N, and the target transfer electric field at the transfer nip N cannot be obtained, resulting in an abnormal image. There is a concern.
That is, in the present embodiment, the separation bias applying means 49 capable of applying a separation bias is provided to the charge removal needle 30 serving as a charge removal member provided downstream of the transfer roller 14 serving as the transfer member in the recording material conveyance direction A. Yes. Then, as shown in FIGS. 18A to 18C, the separation bias with respect to one or both of the front end portion Pc and the rear end portion Pd of the recording material P which is a non-image area is the recording material P. The separation bias is applied from the separation bias applying means 49 so as to be larger than the separation bias with respect to the central portion Pe. FIG. 18A shows a form in which the separation bias at the front end portion Pc and the rear end portion Pd of the recording material P is higher than that at the central portion Pe. FIG. 18B shows a form in which the separation bias at the rear end portion Pd of the recording material P is higher than that of the central portion Pe. FIG. 18C shows a form in which the separation bias at the leading end portion Pc of the recording material P is higher than that at the central portion Pe. The separation bias applying means 49 is a power supply configured to be connected to the output side of the control unit 100 shown in FIG. 5 via a signal line and to control the output by the control unit 100.

  With such a configuration, the separation bias is applied only at the front end portion Pc or the rear end portion Pd of the recording material P, which is a non-image area, or both, or the output of the separation bias is increased, so that an abnormal image is generated. It is possible to stabilize the cleaning of the guide member 32 while suppressing it. The output of the separation bias does not need to be increased at both the front end portion Pc and the rear end portion Pd of the recording material P. Depending on the type of the recording material P, it is sufficient to increase the output only on one side. Can be obtained. Further, by applying a separation bias to the charge eliminating needle 30, it is possible to improve the separation property of the recording material P after passing through the transfer nip N, and the effect of preventing peeling discharge to the photoreceptor 10 can be obtained. .

FIG. 19 is a modification of the tenth embodiment. In this example, the separation bias is output and applied to both the front end portion Pc and the rear end portion Pd of the recording material P higher than the central portion Pe, and the separation bias for the rear end portion Pd is made larger than the front end portion Pc. And output. Further, in this modification, the output timing of the separation bias is performed before the leading end Pc of the recording material P reaches the static elimination needle 30 and continues until after the trailing end Pd passes the static elimination needle 30. It is controlled to be performed.
With such a configuration, the separation bias is applied only at the front end portion Pc or the rear end portion Pd of the recording material P, which is a non-image area, or both, or the output of the separation bias is increased, so that an abnormal image is generated. It is possible to stabilize the cleaning of the guide member 32 while suppressing it. Further, since the separation bias with respect to the rear end portion Pd of the recording material P is larger (higher) than that of the front end portion Pc, the separation property at the rear end portion Pd is improved, and peeling discharge to the photoreceptor 10 is prevented. It is more preferable because it is possible. Further, the output of the separation bias for the front end portion Pc of the recording material P is performed before the front end portion Pc reaches the static elimination needle 30, and the output of the separation bias for the rear end portion Pd of the recording material P is the rear end portion Pd. Is carried out even after passing through the static elimination needle 30. For this reason, even if the conveyance speed of the recording material P fluctuates, it is possible to reliably apply and supply a separation bias to the front end portion Pc and the rear end portion Pd, and to ensure stable separation, and to make a more abnormal image. It is possible to stabilize the cleaning of the guide member 32 while suppressing the occurrence of this.

The method for preventing toner from adhering to the light-transmissive guide member 32 (dirt of the guide member) is not limited to the method of applying a separation bias to the static elimination needle 30. For example, the guide member 32 can be achieved by using a material that hardly adheres to the toner.
Generally, the toner is adjusted to a positive or negative desired charge amount for development and transfer. When the recording material P comes into contact with the guide member 32, the guide member 32 is charged, and when the guide member 32 is charged with a polarity opposite to that of the toner, the scattered toner is electrostatically attracted, and the guide member 32 is soiled. It tends to increase.
For this reason, as the material of the guide member 32, it is preferable to use a material that is a charged column on the same polarity side as the toner with respect to the recording material P. For example, when a negatively charged toner is used, a material having a negative charge column with respect to the recording material P is selected and used. By selecting and using the polar material in this way, even if the recording material P comes into contact with the guide member 32 in the middle of conveyance, the guide member 32 is charged to the negative side, so that the scattered toner is repelled by electrostatic force. In addition, contamination due to toner adhesion can be prevented.
FIG. 20 shows an example of a charged column made of a material. As described above, when minus toner is used, the use of, for example, polypropylene on the minus side where the charge column has the same polarity as the recording material P prevents contamination of the guide member 32 due to toner adhesion. Can do.

  The light transmissive guide member 32 may have conductivity. This is because by making the guide member 32 conductive, the electrostatic force between the toner and the guide member 32 can be reduced, and contamination of the guide member 32 due to toner adhesion can be prevented. For example, by using a conductive polymer having a surface resistance of 10 ^ 12Ω / □ or less as the material of the guide member 32, frictional charging of the guide member 32 during conveyance of the recording material can be prevented, and toner contamination of the guide member 32 can be prevented. Can be prevented.

(Eleventh embodiment)
As described in the first to tenth embodiments, the surface of the photoconductor surface 10a and the deposit X1 are removed by irradiating the photoconductor surface 10a after the transfer and before the cleaning with the static elimination light K from the static elimination light source 26. Can weaken the adhesion. However, if the discharge light K from the discharge light source 26 leaks to the front side of the transfer, that is, upstream of the transfer nip N in the recording material conveyance direction A, the surface of the photoreceptor 10a before transfer is discharged. For this reason, the toner may be scattered from the surface 10a of the photosensitive member before transfer, which may cause a bleeding image (image unevenness).
That is, the static elimination light K from the static elimination light source 26 irradiates the photosensitive member surface 10a by wrapping around the light reflected by other members at both ends in addition to the light directly irradiating the photosensitive member surface 10a. Sometimes. In order to prevent this, if the surface 14a of the transfer roller 14 is provided over the entire width of the photoconductor 10 (including the tube portion other than the effective portion), no gap 52 is formed between the photoconductor surface 10a. .
However, the portion corresponding to the gap 52 in the portion other than the effective length in the axial direction of the photoconductor 10 (portion in consideration of charging, cleaning, etc.) corresponds to the end of the cleaning blade 15. For this reason, a large amount of residual toner remains (because it leaks laterally from the end of the cleaning blade 15). If the surface 14a of the transfer roller 14 is provided up to this portion, all the residual toner is input to the transfer roller 14. (Guidance). That is, since this portion is outside the width of the recording material P, it always comes into contact with the surface 14 a of the transfer roller 14. As described above, when the toner is constantly input to the surface 14a of the transfer roller 14, the transfer roller 14 is cleaned (for example, a mode in which a bias is applied and the toner on the roller surface 14a is retransferred to the photoconductor 10 side). The surface 14a of the transfer roller 14 cannot be cleaned. As a result, the toner is continuously accumulated, so that the end portion and the back surface of the recording material P are stained.
For this reason, the surface 14a of the transfer roller 14 is generally determined in consideration of the maximum sheet passing width. That is, the length of the surface 14a of the transfer roller 14 is generally equal to or longer than the entire width of the recording material P, but may be shortened, but it is desirable to set it to the minimum necessary length. In view of cost, it is desirable to make the transfer roller 14 as short as possible.

Therefore, the transfer roller 14 serving as a transfer member constituting the transfer nip N according to the present embodiment includes a shaft portion 14 b as shown in FIG. 22B, and the shaft portion 14 b is rotated by the frame 51. It is supported freely. Further, the length in the axial direction of the surface 14a of the transfer roller 14 in contact with the photoreceptor surface 10a is shorter than the length in the axial direction of the photoreceptor surface 10a, and is between the shaft portion 14b and the photoreceptor surface 10a. A gap 52 is formed.
When the gap portion 52 is formed in this way, the static elimination light source 26 disposed downstream of the transfer nip N in the recording material conveyance direction A covers the entire axial length of the photosensitive member surface 10a. Irradiating with static elimination light K indicated by a one-dot chain line. For this reason, the static elimination light K is directly or reflected from the gap 52 to the upstream side in the recording material conveyance direction A and leaks as reflected light.

Therefore, in the present embodiment, as shown in FIGS. 21 and 22A, the light shielding means prevents the static elimination light K from the static elimination light source 26 from leaking upstream of the transfer nip N in the recording material conveyance direction A. A light-shielding member 50 is provided so that the static elimination light K does not strike the photoconductor 10 before transfer, preferably the photoconductor surface 10a before transfer. The light shielding member 50 is also a shielding member and is a shielding means.
Specifically, a plate-shaped light shielding member 50 is disposed between the shaft portion 14 b of the transfer roller 14 and the static elimination light source 26. This light shielding member 50 may be provided by, for example, attaching a separate member to a part of the frame 51 for constituting the transfer unit integrally or a part of the frame 51, and the method thereof is not limited.

It goes without saying that the longitudinal direction (width) of the light shielding member 50 is set to a sufficient length necessary for shielding the static elimination light K, and the method therefor is not important. What is important here is that, as shown in FIG. 20, a light shielding member 50 is provided as a light shielding means on the downstream side (upper side in FIG. 20) from the transfer nip N (specifically, the shaft portion 14b of the transfer roller). It is to completely shield the neutralizing light K emitted from the light source 26.
That is, the light shielding member 50 is between the transfer nip N serving as a transfer position and the neutralization light source 26 serving as a light irradiation unit, and more specifically, the photoconductor 10 serving as an image carrier and the transfer roller 14 serving as a transfer member. Is disposed between the gap portion 52 formed between the shaft portion 14 b and the light source portion 26 a of the static elimination light source 26. Further, at least a part of the light shielding member 50 is disposed within the irradiation range W <b> 1 of the static elimination light source 26, and is disposed so as to face the gap 52 and cover the gap 52.
As described above, by providing the light shielding member 50 so that the static elimination light K from the static elimination light source 26 is not directly or indirectly applied to the photosensitive member surface 10a before transfer, the occurrence of a blurred image (image unevenness) is prevented. be able to.

In each of the above embodiments, the copying machine 1 using a single color toner is exemplified as the image forming apparatus. However, the application target of the present invention is not limited to a single color, and for example, a tandem system as shown in FIG. And may be applied to the direct transfer type color copier 1A.
The color copying machine 1A includes image forming units 6Y, 6M, 6C, and 6K that use toner as a developer of yellow, magenta, cyan, and black (Y, M, C, and K), a fixing device 7, and an optical writing device 12. The image forming units 6Y, 6M, 6C, and 6K are mainly provided with a conveying unit 140 and a control unit 100 that are arranged to face each other. The image forming units 6Y, 6M, 6C, and 6K include drum-shaped photoconductors 10Y, 10M, 10C, and 10K as image carriers having a photosensitive layer on each surface 10a. The photoconductors 10Y, 10M, 10C, and 10K are supported so as to be rotatable in a photoconductor rotation direction B that is a counterclockwise direction in the drawing. The photoreceptors 10Y, 10M, 10C, and 10K are rotationally driven in the photoreceptor rotation direction B by a drive motor 40 as a drive source shown in FIG. In the case of the configuration shown in FIG. 15, four drive motors 40 are provided to individually rotate and drive each photoconductor. Around each photoconductor, in accordance with an electrophotographic process, charging rollers 11Y, 11M, 11C, and 11K as charging members, irradiation exposure position B1 of writing light L by the optical writing device 12, and developing devices 13Y, 13M, 13C, and 13K Transfer rollers 14Y, 14M, 14C, and 14K serving as transfer members, and cleaning blades 15Y, 15M, 15C, and 15K serving as cleaning members are sequentially disposed. Each transfer roller and each cleaning blade are in contact with the photoreceptor surface 10a of each color.

  The conveying means 140 transfers the recording material P fed from the tray 4 in the recording material conveying direction A to the transfer nip where the transfer rollers 14Y, 14M, 14C, 14K and the surfaces 10a of the photoconductors 10Y, 10M, 10C, 10K face each other. A transport path 90 for transporting to NY, NM, NC, and NK is formed. The transport unit 140 includes a plurality of rollers 141 and 142 and a transport belt 143 that is wound around the rollers 141 and 142 and rotates counterclockwise in the drawing. The conveyance belt 143 is disposed between the photoconductors 10Y, 10M, 10C, and 10K and the transfer rollers 14Y, 14M, 14C, and 14K, and adsorbs and conveys the recording material P, and as a member that transmits light. Made of transparent material. In the case of this embodiment, the conveyance belt 143 functions as a guide member.

  In such a configuration, the neutralizing light sources 26Y, 26M, 26C, and 26K that irradiate the photosensitive surface 10a of each color with the neutralizing light K are formed on the recording material P with the conveyance path 90 sandwiched between the photosensitive surface 10a of each color. It is arranged inside the loop of the conveyor belt 143 on the back surface Pb side. Then, the neutralizing light K is applied in the width direction on the photoreceptor surface 10a located between the cleaning nips NY2, NM, NC, NK and the cleaning positions B2 with which the cleaning blades 15Y, 15M, 15C, 15K are in contact. Irradiate each. As a result, the adhesion force between each photoreceptor surface 10a and the deposit X1 is reduced, the cleaning property is improved, and the occurrence of black stripes can be suppressed. Furthermore, the scattered toner does not easily adhere to the static elimination light sources 26Y, 26M, 26C, and 26K, and the enlargement of the apparatus can be suppressed while securing the amount of light emitted from each static elimination light source.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments. Unless specifically limited in the above description, the present invention described in the claims is not limited. Various modifications and changes are possible within the scope of the gist.
For example, the image forming apparatus may not be a copying machine, but may be a printer, a facsimile alone, or a multifunction machine having at least two functions of a copying machine, a printer, a facsimile, and a scanner.
The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

1, 1A Image forming apparatus 9A, 9 Conveyance path 10, 10 (Y, M, C, K) Image carrier 10a Image carrier surface 14, 14 (Y, M, C, K) Transfer member 15, 15 ( Y, M, C, K) Cleaning member 25 Static elimination means 26, 26 (Y, M, C, K) Light irradiation means 26a Light source part 30 Static elimination member 32, 143 Light transmissive member, guide member 32a Light source part Opposite parts 40 Drive source 46 Rotational speed detection means 47 Usage rate detection means 48 Environmental condition detection means 49 Separation bias application means 50 Light shielding member 51 Gap part 100 Control part A Recording material conveyance direction B2 Cleaning position N Transfer position P Recording material Pb Back surface of the recording material Pc Front end portion of the recording material Pd Rear end portion of the recording material Pe Central portion of the recording material W Width direction W1 Whole area of the light irradiation means (irradiation range)
X1 Deposit (paper powder)

JP 2002-072710 A

Claims (23)

A rotatable image carrier having a photosensitive layer on the surface;
A transfer member that forms a transfer position for transferring a visible image formed on the surface of the image carrier onto a recording material conveyed along a conveyance path;
A cleaning member that forms a cleaning position for cleaning deposits adhering to the surface of the image carrier after transfer at the transfer position;
A light irradiation means for irradiating light on the surface of the image carrier located between the transfer position and the cleaning position;
The light irradiating means is disposed on the back side of the recording material across the transport path with respect to the surface of the image carrier,
An image forming apparatus in which a light-transmissive member is disposed between the light irradiation unit and the photosensitive member. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the light transmissive member is a guide member for guiding conveyance of the recording material. The image forming apparatus according to claim 2.
The guide member is an image forming apparatus in which a portion facing the light source part of the light irradiation unit is formed on a flat surface. The image forming apparatus according to claim 1, 2 or 3.
The light irradiation unit is an image forming apparatus in which a light source unit is a light emitting diode or electroluminescence. The image forming apparatus according to any one of claims 1 to 4, wherein:
The image forming apparatus, wherein the light transmissive member is formed so as to cover the entire area of the light irradiation unit in a width direction intersecting on the same plane as the conveyance direction of the recording material. The image forming apparatus according to any one of claims 1 to 5,
A control unit for controlling light emission of the light irradiation means;
The control unit is an image forming apparatus that controls the light emission timing of the light irradiation unit to be synchronized with an operation timing of a drive source that rotationally drives the image carrier. The image forming apparatus according to any one of claims 1 to 5,
A control unit for controlling light emission of the light irradiation means;
The control unit controls the light emission timing of the light irradiation unit so as to synchronize with a timing of applying a transfer bias to the transfer member. The image forming apparatus according to any one of claims 1 to 5,
The light irradiation means can adjust the light emission amount,
An image forming apparatus having a control unit for controlling a light emission amount of the light irradiation unit. The image forming apparatus according to claim 8.
The control unit is an image forming apparatus that controls a light emission amount of the light irradiation unit according to a conveyance timing of the recording material. The image forming apparatus according to claim 9.
The control unit controls the light irradiation unit so that the amount of light emission is strong when the recording material is conveyed along the conveyance path and the amount of light emission is weak when the recording material is not conveyed along the conveyance path. Image forming apparatus. The image forming apparatus according to claim 8.
A rotation speed detecting means for detecting the rotation speed of the image carrier;
The control unit controls the light irradiation unit so that the light emission amount is strong when the rotation speed detected by the rotation speed detection unit is large and the light emission amount is weak when the rotation speed is low. . The image forming apparatus according to claim 8.
Having a usage rate detecting means for detecting the usage rate of the cleaning member;
The control unit is an image forming apparatus that controls the light irradiation unit such that the light emission amount increases as the usage rate detected by the usage rate detection unit increases. The image forming apparatus according to claim 8.
Having environmental condition detection means,
The control unit is an image forming apparatus that controls a light emission amount of the light irradiation unit based on a detection result of the environmental condition detection unit. The image forming apparatus according to claim 13.
The environmental condition detecting means detects the temperature and humidity inside and outside the apparatus,
The image forming apparatus that controls the light emission amount of the light irradiation unit so that the light emission amount gradually decreases as the absolute humidity obtained from the detection value of the environmental condition detection unit increases. The image forming apparatus according to claim 8.
The control unit is configured so that the light emission amount of the light irradiation unit is stronger than the light emission amount with respect to the central portion of the recording material with respect to either one or both of the front end portion and the rear end portion of the recording material. An image forming apparatus for controlling light irradiation means. The image forming apparatus according to any one of claims 1 to 15,
An image forming apparatus, comprising: a discharging unit that discharges a residual potential of the image carrier by irradiating light on a surface of the image carrier located between the cleaning position and the charging member. The image forming apparatus according to any one of claims 1 to 16,
A static elimination member provided downstream of the transfer member in the recording material conveyance direction;
A separation bias applying means capable of applying a separation bias to the static elimination member;
An image for outputting a separation bias from the separation bias applying means so that a separation bias for one or both of the leading edge and the trailing edge of the recording material is larger than a separation bias for the central portion of the recording material. Forming equipment. The image forming apparatus according to any one of claims 1 to 17,
The image forming apparatus is arranged such that the light irradiation unit is irradiated with light toward a rotation center of the image carrier. The image forming apparatus according to any one of claims 1 to 18,
The image forming apparatus, wherein the light transmissive member is made of a material that is a charged column on the same polarity side as the toner with respect to the recording material. The image forming apparatus according to any one of claims 1 to 19,
The light transmissive member is a conductive image forming apparatus. 21. The image forming apparatus according to claim 1, wherein:
An image forming apparatus in which a light shielding unit is disposed between the transfer position and the light irradiation unit. The image forming apparatus according to claim 21, wherein
The light shielding unit is an image forming apparatus disposed between a gap formed between the image carrier and the transfer member and the light irradiation unit. The image forming apparatus according to claim 22, wherein
An image forming apparatus in which at least a part of the light shielding unit is disposed within an irradiation range of the light irradiation unit, and is disposed so as to face the gap and cover the gap.

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