JPH1124420A - Image forming device - Google Patents

Abstract

(57) Abstract: An image forming apparatus capable of supplying a cleaning aid to a photoconductor while maintaining the diameter of the photoconductor. An image forming apparatus includes a rotatable photoconductor.
And a plurality of image forming elements (for example, a developing device 13 or the like) arranged around the photoreceptor, and a visible image is formed on the photoreceptor by the plurality of image forming elements. Is transferred to a member to be transferred (for example, a sheet substrate 27), and a part of the visible image remaining on the photoreceptor without being transferred to the member to be transferred is then transferred to one of a plurality of image forming elements (cleaning). Means 14) are collected. The transfer device 20 is provided with an auxiliary agent supply device 35 that supplies a cleaning auxiliary to the photoreceptor to promote the recovery of the residual toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus for forming a visible image on an outer peripheral surface of an image carrier and transferring the visible image to a sheet base material such as paper to form an image.

2. Description of the Related Art As a developer used in an electrophotographic image forming apparatus (for example, a copying machine or a printer), the surface of a toner is improved in order to improve fluidity of the developer and reproducibility of an area image (solid image). It has been known that a post-processing agent having a considerably smaller diameter than the toner is adhered to the toner. This post-treatment agent has no problem as long as it is held on the fine irregularities on the surface of the toner, but it causes a problem if the toner is separated from the toner by being stressed by stirring or the like.

To explain the problem specifically, in general, an electrophotographic image forming apparatus presses a blade against the outer peripheral surface of a photoconductor in order to collect untransferred toner from the photoconductor. Since the post-treatment agent has a considerably smaller diameter than the toner, it passes through the contact portion between the blade and the photoconductor. Further, when passing through the contact portion between the blade and the photoreceptor, the post-processing agent is rubbed against the photoreceptor by the pressure contact force of both, and a film is formed on the surface of the photoreceptor. Then, the portion where the film is formed on the photoreceptor has reduced chargeability, and noise (spots and streaks) appears on the corresponding portion on the finally completed image.
Is generated.

In order to solve this problem, a transfer station for transferring a toner image formed on a photoreceptor to a sheet substrate such as paper, and the above-described blade is used to scrape untransferred toner on the photoreceptor. A cleaning aid supply station is provided between the cleaning station and the cleaning aid supply station. The cleaning aid supply station supplies a cleaning aid (for example, strontium titanate) to the photoreceptor for promoting the recovery of the post-processing agent by the blade. An image forming apparatus is disclosed in U.S. Pat. No. 5,220,390.

[0005]

However, in the image forming apparatus disclosed in the above-mentioned U.S. Patent, a dedicated space for a cleaning aid supply station is required around the photosensitive member, so that the photosensitive member is increased in size accordingly. There must be. In particular, in an image forming apparatus that creates a full-color image using a plurality of photoconductors, if a cleaning aid supply station is provided around each photoconductor, the image forming apparatus becomes considerably large.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of supplying a cleaning aid to a photoreceptor while keeping the diameter of the photoreceptor unchanged.

In order to achieve this object, an image forming apparatus according to a first aspect of the present invention comprises a rotatable image carrier and a plurality of image forming elements (for example, a charging device, Exposing device, developing device, etc.), forming a visible image on an image carrier by using the plurality of image forming elements, and then transferring the visible image to a member to be transferred (for example, a sheet base material).
Then, a part of the visible image remaining on the image carrier without being transferred to the member to be transferred is collected by one of the plurality of image forming elements (cleaning means). I have. The image forming element includes a transfer unit that rotates while contacting the image carrier, and transfers a visible image on the image carrier to a member to be transferred. Auxiliary supply means for supplying an auxiliary agent (cleaning auxiliary agent) for accelerating the recovery of the residual visible image to the transfer unit is provided on the side of the transfer unit, and the auxiliary unit is supplied to the image carrier via the transfer unit. It is made to supply.

In the above image forming apparatus, the transfer means includes a cylindrical member (for example, an endless belt or a cylindrical drum) which includes an endless surface and rotates while bringing the endless surface into contact with the outer peripheral surface of the image carrier. A suction means disposed inside the shape surface to face the image carrier and electrically suctioning a visible image from the image carrier toward the endless surface; and an auxiliary agent supply means assisting the endless surface. The agent may be supplied and supplied to the image carrier via the endless surface.

The transfer member passes through a contact portion between the image carrier and the cylindrical member, and the contact portion causes the visible image on the image carrier to be transferred to the transfer member by suction means. Is also good. Instead, the transferred member contacts the endless surface of the cylindrical member in a region other than the contact portion between the image carrier and the cylindrical member,
The visible image may be transferred from the image carrier to the endless surface of the tubular member, and may be transferred from the endless surface of the tubular member to the member to be transferred.

Further, it is preferable that the supply of the auxiliary agent from the endless surface of the cylindrical member to the image carrier is promoted by the suction means.

An image forming apparatus according to a second embodiment of the present invention includes an endless belt rotatably supported, a plurality of image carriers arranged in contact with an outer peripheral surface of the endless belt, and an outer periphery of the image carrier. Means for forming a visible image on each surface, and passing the sheet base material through a plurality of contact portions where the endless belt and the plurality of image carriers come into contact with each other, and forming the visible image formed on the outer peripheral surface of the plurality of image carriers. Means for sequentially transferring images to the sheet substrate, removing means for removing untransferred visible images remaining on the outer peripheral surfaces of the plurality of image carriers passing through the plurality of contact portions from the image carrier, and removing means. Auxiliary supply means for supplying an auxiliary for promoting removal of the untransferred visible image to the outer periphery of the endless belt.

[0012]

According to the above-mentioned image forming apparatus, the auxiliary agent (cleaning auxiliary agent) is first supplied to the transfer means. Next, the auxiliary agent is supplied from the transfer unit to the photoconductor at a contact portion between the transfer unit and the photoconductor. Thereafter, the auxiliary agent is supplied to a component (cleaning member) that collects a residual visible image from the surface of the image carrier in one of the plurality of image forming elements based on the rotation of the image carrier. Thus, according to the image forming apparatus of the present invention, the auxiliary agent supply unit is not at the side of the photoconductor,
The auxiliary agent can be supplied to the photoconductor without increasing the diameter of the photoconductor because it is provided on the side of the transfer unit that comes into contact with the photoconductor.

[0013]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a main part of a full-color image forming apparatus (for example, a copying machine or a printer). The image forming apparatus has four cylindrical photoconductors ("image carrier" in a broad sense) 10 (10c, 10m, 10y, 10k). In the present embodiment, each photoconductor 10 has the same configuration and size, is arranged in parallel on a horizontal plane at a predetermined interval, is driven and connected to a motor (not shown), and is individually connected in the direction of the arrow (in the drawing). (Upward clockwise direction).

A plurality of image forming elements--a charging device 11, an exposure device 12, a developing device 13, a cleaning device 14, and a charge removing device 15--are arranged around each photoreceptor 10. The charging device 11 charges the outer peripheral surface of the photoconductor 10 to a predetermined potential, and a non-contact discharger such as a scorotron or a corotron or a contact charger such as a brush roller or a blade is used.

The exposure device 12 is preferably a laser optical system that emits a laser based on digital image information. The exposure device 12 exposes a charged area of the photoreceptor 10 charged by the charging device 11 to a laser beam and responds to the image information. To form an electrostatic latent image.

The developing device 13 is a known developing device using a so-called one-component developer or a two-component developer.
The developing devices 13 for 0c, 10m, 10y, and 10k contain cyan, magenta, yellow, and black toners, respectively. The developing device 13 also includes a developing roller 16. The developing roller 16 is connected to a developing bias power supply 17 so that a predetermined developing bias can be applied to the developing roller 16. Based on a potential difference between the developing bias and the surface potential of the photoconductor 10, the developing roller 16 The toner is supplied to the body 10 to form a toner image (a “visible image” in a broad sense). In order to avoid complicating the drawing, the developing bias power supply 17 is shown only for the rightmost developing device in the drawing, and other developing bias power supplies are omitted.

The cleaning device 14 has a blade 19. The blade 19 is disposed in parallel with the photoconductor 10, one end is fixed, and the other free side corner is the photoconductor 1.
0 is pressed against the outer peripheral surface of the photosensitive member 1
0 is removed.

The static eliminator 15 uses a lamp.
The surface of the photoreceptor before charging is illuminated to remove the residual charge and prepare for the next charging.

The photosensitive member 10 (10c, 10m, 10y, 1
Below 0k), a transfer device 20 is provided. The transfer device ("transfer means" in a broad sense) 20 constitutes an image forming element for each photoconductor together with the charging device 11, the developing device 13, and the like. The transfer device 20 has a cylindrical endless belt 21 ("tubular member" in a broad sense). The endless belt 21 has an endless surface 22 on its outer periphery, is supported by a pair of rollers (a driving roller 23 and a driven roller 24) disposed inside, and is rotated in the direction of the arrow (counterclockwise in the drawing) by rotation of the driving roller 23. Direction). Inside the belt 21, each photoconductor 10 (10 c, 10 m, 10 y, 10
There are provided a plurality of transfer rollers ("suction means" in a broad sense) 25 which face the photoreceptor 10 (10c, 10m, 10y, 10k) while supporting the inner peripheral surface of the belt 21 in opposition to k). Each transfer roller 25 is provided with a transfer bias power supply 26.
And the voltage applied to the transfer roller 25 can be switched as described later.

In the vicinity of the driven roller 24, the driven roller 2
4 on the outer periphery of the upper belt portion moving toward the drive roller 23 (in a broad sense, “transfer member”) 2
The paper feed guide 28 for supplying the sheet 7 is provided. Above the driven roller 24, a charging device 29 for charging the sheet base material supplied to the upper belt portion to a predetermined polarity as described above is provided. Further, a belt cleaning device 30 is provided near the belt portion supported by the driven roller 24. The belt cleaning device 30 includes a blade 31, and one end of the blade 31 can contact and separate the outer peripheral surface of the belt 21.

In the vicinity of the driving roller 23, there is provided a static eliminator 32 for removing the electric attraction between the belt 21 and the sheet substrate supported by the belt 21 to separate the sheet substrate from the belt 21. And a roller pair 33 for conveying the sheet base material separated from the belt 21 to the next step.

Outside the lower belt portion that moves from the driving roller 23 toward the driven roller 24, a cleaning aid application device (in a broad sense, "auxiliary supply means") 35 is provided. The cleaning aid application device 35 includes a container 36 containing a cleaning aid (for example, strontium titanate), an application roller 37 for applying the cleaning aid contained in the container 36 to the outer peripheral surface of the belt 21,
The application roller 37 is pressed against the application roller 37, and the application roller 37 is
And a regulating member 38 that charges the cleaning assistant to a predetermined polarity (+ polarity in the present embodiment) based on the rotation of the cleaning roller and causes the cleaning assistant to adhere to the application roller 37. Corona discharge type static elimination devices 39 and 40 are provided on the outside and inside of the belt 21 so as to face the outside and inside surfaces of the lower belt portion, respectively.

The operation of the image forming apparatus having the above configuration will be described. At the time of image formation, each photoconductor 10 (10c, 10c
m, 10y, and 10k) rotate in the directions of the arrows, and are charged to a predetermined potential (for example, −600 V) by the charging device 11. Next, each photoconductor 10 (10c, 10m, 1
On the outer peripheral surfaces of 0y and 10k), image light corresponding to the colors of cyan, magenta, yellow and black is exposed by the exposure device 12, respectively, and an electrostatic latent image corresponding to these image lights is formed. Next, the photoconductor 10 (10
c, 10m, 10y, and 10k), the cyan, magenta, yellow, and black toners are supplied from the developing device 13 to their potential attenuated portions (exposed portions), respectively, so that a visible image is formed as a toner image. Be transformed into

Here, the development is performed on the photosensitive member 10 (10c, 1c).
0m, 10y, 10k) and the developing bias (for example,-
Based on the potential difference between the toner and the developing device 13, the toner charged to the negative polarity from the developing device 13 is electrically attracted to the potential attenuating portions, respectively.

Sheet substrate 27 to which the toner image is transferred
Is guided by a paper feed guide 28 and supplied onto the upper belt portion. Above the sheet substrate 27 that has reached the belt 21, the charging device 29 is activated, whereby positive charges are injected into the sheet substrate 27. Next, the sheet substrate 27 is conveyed with the rotation of the belt 21, and the photoconductor 10 (10c,
10m, 10y, 10k) and the contact portion 42 between the belt 21
(42c, 42m, 42y, 42k).

When the sheet base 27 is in contact with the contact portions 42 (42c,
2m, 42y, and 42k), each transfer roller 2
5 (25c, 25m, 25y, 25k) with a positive polarity voltage (for example, 25c is + 4KV, 25m is + 5KV,
+6 KV is applied to 25y, and +7 KV is applied to 25k, whereby each photoconductor 10 (10c, 10m, 10y, 10y) is applied.
The negative polarity toner images (cyan, magenta, yellow, and black toner images) formed in (k) are sequentially electrically attracted to and adhered to the sheet substrate 27. The sheet substrate 27 on which all the toner images have been transferred as described above is
After the charge is removed by the discharge of the static eliminator 32 on the drive roller 23 and released from the electric attraction with the belt 21, the charge is separated from the belt 21 by its own stiffness. Transported to On the other hand, the portion of the belt 21 separated from the sheet base 27 is
After the static elimination in steps 9 and 40, the cleaning blade 31 removes deposits such as paper dust in the contact area with the driven roller 24.

At the time of non-image formation, specifically, immediately before the image forming operation is started or immediately after the image forming operation is completed, the following cleaning aid supply process is executed (see FIG. 2).
In the present cleaning aid supply process, the photoconductor 10 (10
c, 10 m, 10 y, and 10 k) are charged to a predetermined voltage (−600 V) by the charging device. The developing bias voltage applied to the developing roller 16 is the same potential (-600 V) as the charged potential of the photoconductor (step S102). As a result, unnecessary adhesion of the toner from the developing device 13 to the photoconductor 10 (10c, 10m, 10y, 10k) is prohibited.

In the transfer device 20, the belt 21 rotates based on the rotation of the driving roller 23. Further, the transfer roller 25
, A negative polarity voltage is applied to the
A negative polarity charge is injected into the outer peripheral surface of the substrate 1. In the cleaning aid application device 35, the application roller 37 rotates,
A cleaning aid is applied to the outer periphery of the application roller 37 by the application member 38. At this time, the cleaning aid sandwiched between the application roller 37 and the application member 38 is charged to a positive polarity by frictional contact therebetween, and is electrically attracted to the belt 21 charged to a negative polarity. The cleaning aid held on the outer periphery of the belt 21 in this manner, as the belt 21 rotates, the photoconductor 10 (10c,
10m, 10y, 10k) and the contact portion 42 between the belt 21
(42c, 42m, 42y, 42k). In the cleaning device 30 of the transfer device 20, the blade 31 is separated from the belt 12 (step S10).
1) The blade 31 is prevented from scraping the cleaning aid.

When the cleaning aid is conveyed to the opposing portion of the photoconductor 10c and the belt 21, a positive voltage is applied to the transfer roller 25c facing the photoconductor 10c.
Thus, the positively charged cleaning aid held on the belt 21 is supplied to the photoconductor 10c (steps S103, S104, and S105). At this time, a negative polarity voltage is applied to the other transfer rollers 25m, 25y, and 25k, and the corresponding photoconductors 10m, 10y,
Supply of cleaning aid to 10k is prohibited.

After a predetermined time, the voltage applied to the transfer roller 25c is switched from a positive polarity to a negative polarity, and
The voltage applied to the next transfer roller 25m is switched from negative polarity to positive polarity, and a cleaning assistant is supplied to the photoconductor 10m this time (steps S203 and S20).
4, 105). Thereafter, the photoconductors 10y, 1
0k is supplied with a cleaning aid (step S30).
3, 304, 105, steps S403, 404, 40
5).

As described above, all the photoconductors 10c,
When the cleaning assistant is supplied to 10m, 10y, and 10k, the cleaning blade 31 of the transfer device 20 comes into contact with the belt 21 again (Step S106).

The photosensitive member 10 (10c, 10m, 10y, 1
0k) is carried to the cleaning device 14 according to the rotation of the photoreceptor 10 and is held at the tip position of the blade 19 to collect the toner and the post-processing agent having a smaller diameter than the toner by the blade 19. Facilitate. As a result, the photoconductor 10 (10c, 10m, 10y,
At 10k), a film of the post-treatment agent is not formed, and the chargeability thereof is favorably maintained.

In the cleaning aid supply control described above, the transfer roller 25 (25c, 25m, 25y, 25y
The cleaning aid is supplied only to the target photoreceptor by switching the polarity of the voltage applied to k). However, the transfer roller 25 can be made to move forward and backward with respect to the photoreceptor 10 and driving means such as a solenoid and a motor are used. By pressing and separating the photoreceptor 10 with the belt 21 via the transfer roller 25, the cleaning aid may be supplied only to the intended photoreceptor.

In the above description, the present invention has been described by taking an image forming apparatus having a plurality of photoconductors as an example. However, the present invention can be applied to an image forming apparatus having only one photoconductor. Further, although the present invention has been described by taking a belt type transfer device as an example of a transfer device as an image forming device, the transfer device may be of another type (a roller type transfer device). Further, the sheet material is passed between the belt and the photoconductor, where the toner image is transferred from the photoconductor to the sheet material. However, the toner image is temporarily transferred to a transfer member (transfer belt, transfer drum). The present invention is also applicable to an image forming apparatus in which a toner image is transferred from the transfer member to a sheet substrate after that.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an image forming apparatus according to the present invention.

FIG. 2 is a flowchart of a cleaning aid supply control.

FIG. 3 is another flowchart of cleaning aid supply control.

[Explanation of symbols]

10 photoreceptor, 11 charging device, 12 exposure device, 13
... developing device, 14 ... cleaning device, 20 ... transfer device, 21 ... endless belt, 25 ... transfer roller, 35 ... cleaning assistant application device.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuhiro Sakamoto 2-3-13 Azuchicho, Chuo-ku, Osaka City, Osaka Prefecture Inside the Osaka International Building Minolta Co., Ltd. (72) Shinya Matsuura Inventor Shinya Azuchicho, Chuo-ku, Osaka City, Osaka 2-3-13 Osaka International Building Minolta Co., Ltd.

Claims (8)

[Claims] 1. An image forming apparatus comprising: a rotatable image carrier; and a plurality of image forming elements disposed around the image carrier, wherein the plurality of image forming elements form a visible image on the image carrier. Creating and transferring the visible image to a member to be transferred, and recovering a part of the visible image remaining on the image carrier without being transferred to the member to be transferred by one of the image forming elements In the electrophotographic image forming apparatus, the image forming element rotates while being in contact with the image carrier, and includes a transfer unit that transfers a visible image on the image carrier to a member to be transferred. Auxiliary supply means for supplying an auxiliary agent for promoting the recovery of the residual visible image is provided on the side of the transfer means, and the auxiliary agent is supplied to the image carrier via the transfer means. An image forming apparatus comprising: 2. The image forming apparatus according to claim 2, wherein the transfer unit includes a cylindrical member including an endless surface and rotating while bringing the endless surface into contact with an outer peripheral surface of the image carrier. And suction means for electrically suctioning the visible image from the image carrier toward the endless surface, wherein the auxiliary agent supply means includes the auxiliary agent on the endless surface. 2. The image forming apparatus according to claim 1, wherein the image is supplied to the image carrier through the endless surface. 3. The image forming apparatus according to claim 2, wherein said tubular member is an endless belt. 4. The image forming apparatus according to claim 2, wherein said cylindrical member is a cylindrical drum. 5. The transfer member passes through a contact portion between the image carrier and the cylindrical member, and a visible image on the image carrier is transferred to the transfer member by the suction means at the contact portion. The image forming apparatus according to claim 2, wherein the image is transferred. 6. The transfer member contacts an endless surface of the cylindrical member in a region other than a contact portion between the image carrier and the cylindrical member, and the visible image is transferred from the image carrier to the cylindrical member. The image is transferred to the endless surface of the cylindrical member, and then transferred from the endless surface of the cylindrical member to the member to be transferred.
Any one of the image forming apparatuses. 7. The image forming apparatus according to claim 2, wherein the supply of the auxiliary agent from the endless surface of the cylindrical member to the image carrier is promoted by the suction unit. 8. An endless belt rotatably supported, a plurality of image carriers arranged in contact with an outer peripheral surface of the endless belt, and a visible image formed on an outer peripheral surface of the image carrier. Means, the sheet base material is passed through a plurality of contact portions where the endless belt and the plurality of image carriers are in contact with each other, and the visible images formed on the outer peripheral surfaces of the plurality of image carriers are sequentially printed on the sheet substrate. Means for transferring the untransferred visible image remaining on the outer peripheral surface of the plurality of image carriers passing through the plurality of contact portions from the image carrier; and An auxiliary supply means for supplying an auxiliary for promoting removal of a visible image of transfer to the outer periphery of the endless belt.