JP3347713B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus utilizing an electrophotographic technique, such as a copying machine and a laser beam printer.

[0002]

2. Description of the Related Art Conventionally, various types of color image forming apparatuses have been proposed, but an image forming section is provided for each color developer, and in each image forming section, a photosensitive drum as an image carrier is well known. There is an electrophotographic color image forming apparatus that forms a visual image for each color in the image forming process, sequentially transfers the visual images to a transfer material supplied from the visual images, and collectively fixes the color images. In this case, the transfer material is placed on a transport belt that moves endlessly and is sequentially transported to each image forming unit, and the visible image formed on each photosensitive drum is sequentially transferred to the transfer material. Also, for cleaning dirt on the conveyor belt, for example, fogging toner or paper dust, for example,
A rotary cleaning means such as a fur brush is provided to prevent the back surface of the transfer material from being stained. In addition, a static eliminator is provided downstream of the image forming unit with respect to the moving direction of the conveyor belt and upstream of the cleaning unit. During cleaning, the electrostatic force of the conveyor belt and the residual toner on the conveyor belt is neutralized and combined with each other. , The cleaning of the residual toner is facilitated.

[0003]

However, in the above-mentioned conventional example, static electricity is generated by the rubbing of the cleaning means and the transport belt, so that the transport belt is recharged even if the charge is removed before cleaning. This means that this device uses electrostatic force as a process to attract the transfer material, transfer the image on the photosensitive drum to the transfer material, and separate the image-formed transfer material from the transport belt. For this reason, the recharging of the conveyor belt by the cleaning means has been a factor of causing a jam (paper jam) due to poor transfer material adsorption and separation, and an abnormal image due to poor transfer in the next image formation.

[0004] In addition, since charging due to friction changes remarkably depending on the environment or the like, it has been a serious drawback as an unstable factor.

As a method for solving the above problem, there is a method in which only static elimination is performed by the static elimination means before the cleaning means during image formation. However, since the static elimination means is located before the cleaning means, cleaning is performed during image formation. Since it is impossible to operate the means from the viewpoint of avoiding triboelectric charging, the cleaning means must be operated after the completion of image formation. There is a disadvantage. Further, when image formation is continuously performed on the transfer material, since the remaining toner is not cleaned by the cleaning unit after the second rotation of the transport belt, the fog toner adheres to the back surface of the transfer material that is attracted. There are also disadvantages.

[0006]

The problem to be solved by the present invention is solved by the following means.

According to a first aspect of the present invention, there is provided an image forming section provided with an image carrier on which a visible image is formed, and an image carrier adjacent to the image carrier, which carries and conveys a transfer material by electrostatic attraction. a conveying device provided with a transfer material transport belt passing through a position for transferring the visible image, has a cleaning means for cleaning the conveyance belt, with respect to the moving direction of the conveyance belt, the transfer material
Downstream of the position where is separated and upstream of the cleaning means, and
An image forming apparatus characterized by providing a respective dividing <br/> conducting means downstream of the upstream and the cleaning means of the image forming unit.

According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the cleaning means operates during image formation.

According to a third aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein after the image formation is completed, the operation of the charge removing means is terminated after the conveyance belt is stopped.

A fourth aspect of the present invention is the image forming apparatus according to the first aspect, wherein the transport device includes an endless flexible belt as the transfer material transport belt.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows Embodiment 1 and is a schematic sectional view in which the present invention is applied to an electrophotographic color copying machine.

FIG. 1 shows a color image forming apparatus. In the figure, image forming units PM, PC, PY, and PK for forming images of magenta, cyan, yellow, and black are arranged along the transfer material transporting device 60. Each image forming unit P
M, PC, PY, and PK have the same configuration, and each of the constituent members has a numeral code next to any of the last MCYKs in the code representing each image forming unit. FIG. 2 shows the image forming unit PK. Therefore, in the description common to each image forming unit, the same reference numerals as those at the end of the image forming unit are omitted.

A primary charger 2 for uniformly charging the surface of the photosensitive drum 1 around the photosensitive drum 1 rotating in the direction indicated by an arrow, a scanning optical device 3 including a laser light source, a collimator lens, and a polygon mirror, and scanning. Lens 1 for forming an image sent from optical device 3 on photosensitive drum 1
7, a developing device 4 for converting a latent image on the photosensitive drum 1 into a visible image, and a charge for transferring the visible image to a transfer material P sent from the right to the left in the drawing by the transfer material transport device 60 And a cleaning device 5 for cleaning the remaining toner on the photosensitive drum 1 after the transfer. In the transfer material transporting device 60, a transport belt 6 is stretched as a transfer material carrying sheet of a dielectric endless belt between a driving pulley 6a and a driven pulley 6b.

The controller 100 manages each of the above detection information and controls each image forming condition. Next, the order of image formation will be described. Primary charger 2 is uniformly applied to photosensitive drum 1
Charging is performed. Next, a light image is exposed by the scanning optical device 3, and this light image is based on a signal scanned and read by a document reading scanner (not shown) and subjected to image processing. Exposure of this light image causes the photosensitive drum 1
Is formed with a potential latent image. This latent image is subsequently developed with toner by the developing device 4 to become a visible image. The sheet feeding device 65 is synchronized with the formation of the visible image of each image forming unit and the timing.
The transfer material P is fed out from a paper feed cassette 61 by a paper feed roller 62 and guided by a paper feed guide 63 to be fed.
Next, the transfer material P is sent to the conveyor belt 6 with the oblique direction corrected by the registration rollers 64 and the timing adjusted. Thereafter, the toner image is transferred by a transfer charger 7 onto a transfer material P that is carried on a transport belt 6 and moves in the direction of the arrow shown in the figure. The above steps are for magenta, cyan, yellow,
A full-color image repeated at each of the black stations PM, PC, PY, and PK is obtained. The transfer material P on which the multiple transfer is performed is fixed by the fixing device 8, and is discharged onto the tray 117 from the transfer material discharge port 24.

A suction charger (not shown) is provided between the first image forming unit PM and the paper feeding device 65, and the suction charging device is provided with a transfer material supplied from the paper feeding device 65. Corona discharge is performed to ensure that P is adsorbed to the conveyor belt 6. On the other hand, a static eliminator (not shown) is provided almost directly above the drive pulley 6 a between the fourth image forming unit PK and the fixing device 8, and the static eliminator is attracted to the transport belt 6. An AC voltage is applied to separate the transferred transfer material P.

In this embodiment, a cleaning means 90 is provided for cleaning the dirt adhering to the transfer material mounting surface of the transfer belt 6 as the transfer material transfer means. The cleaning means 90 includes a frame 91, a fur brush 92, and a drive motor (not shown) for driving the fur brush. The axial center of the fur brush 92 is set in a direction substantially perpendicular to the moving direction of the transport belt 6. The motor is rotated at about 3000 rpm by the drive motor in the reverse direction in the opposite direction. The driving of the fur brush 92 is controlled by a microcomputer provided in the main body, and is turned on and off at a predetermined timing. Adjacent to the cleaning means 90, on the upstream side in the moving direction of the transport belt 6, static elimination chargers 93a and 93b that generate corona discharge in conjunction with the fur brush 92 are provided so as to sandwich the transport belt 6. The static eliminator 93
With a and 93b, charges on the conveyor belt 6 generated by a series of image forming processes can be removed. Therefore, since the electric coupling force between the residual toner (fogging toner) transferred onto the transport belt 6 and the transport belt 6 can be removed, the removal of the fogging toner by the cleaning unit 90 is facilitated.

Similarly, between the cleaning means 90 and the driven pulley 6b, static eliminators 93c and 93d are arranged.
Therefore, it is possible to neutralize the transfer belt 6 that has been frictionally charged by the fur brush 92, and it is possible to always stably adsorb the transfer material P to the transfer belt 6 and transfer the toner image. Static eliminators 93a, 93b, 93c,
Since a high AC voltage is applied to 93d, the latitude is wide with respect to static elimination, but each DC component can be adjusted in case an optimum value is obtained.

FIG. 2 is a flow chart of the apparatus control of this embodiment, and FIG. 3 is a timing chart showing the time Ti (i = 1, 2,...) On the horizontal axis. When a copy start command is received from the user, in step 1 (T1), the photosensitive drum 1
M, 1C, 1Y, 1K, conveyor belt 6, fur brush 9
2 is driven, and at the same time, A
C, a high voltage is applied, and the conveyor belt 6 is neutralized. Next, as described above, the transfer material P is fed in step 2 (T2). In step 3 (T3), the timing of feeding the transfer material P and the timing of the visible image formed on the photosensitive drums 1M to 1K are determined. Each color is sequentially superimposed to form a color image on the transfer material P. In step 4 (T3 '), the above operation is repeated at the time of continuous copying of a plurality of sheets by the user's specification. During the image formation, the fur brush 92 and the static eliminators 93a to 93d continue to operate, so that the residual toner and dust transferred onto the conveyor belt 6 are always removed, and the fur brush 92 and the conveyor belt 6 slide. Since re-charging of the transport belt 6 due to rubbing can be removed, stable transfer, transfer, transfer and separation of the transfer material P can be performed even during a large amount of continuous copying, and back contamination of the transfer material P can be prevented. At step 5 (T4), a series of image formation is completed, and when the discharge is detected by a discharge sensor (not shown), step 6 is subsequently performed.
At (T5), first, the photosensitive drums 1M to 1K, the transport belt 6,
The fur brush 92 is stopped at the same time, and Step 7 (T6)
As a result, the static elimination chargers 93a to 93d are turned off after a certain interval. Therefore, it is possible to prevent the charge removal remaining due to the movement of the transport belt 6 due to the inertial force when the belt is stopped. As described above, during the next image formation, the wait time can be reduced and stable image formation can be performed.

[Embodiment 2] FIG. 4 is a view showing Embodiment 2 of the present invention, and the same reference numerals as those in Embodiment 1 have the same functions. In this embodiment, the cleaning means 90 and the driven pulley 6
A conductive brush 94 grounded to the copying machine main body 30 is arranged between the points b and b to obtain the same effect as in the first embodiment.
Although it is impossible to adjust the static elimination as in the first embodiment, there is an advantage that no cost is required.

FIG. 5 is a flow chart of the apparatus control in this embodiment. The order of operation is the same as in the previous embodiment, and the charge is always removed by the conductive brush 94 when the transport belt 6 moves.

[0022]

According to a first aspect of the present invention, there is provided an image forming section provided with an image carrier on which a visible image is formed, and an image carrier which is adjacent to the image carrier and which carries and conveys a transfer material by electrostatic attraction. has a conveying apparatus having a transfer material transport belt <br/> passing the position for transfer of the visible image, the cleaning means for cleaning of the conveyor belt, and about the direction of movement of the conveyor belt , Transfer material
Downstream of the position where is separated and upstream of the cleaning means, and
Wherein by the image forming apparatus characterized by providing a respective dividing <br/> conducting means downstream of the upstream and the cleaning unit of the image forming unit, and reliably remove the dirt on the transfer material conveying belt,
Also, the charge of the transfer material transport belt by the cleaning means is removed,
This enables stable image formation on the transfer material. Therefore, the cleaning unit can be operated during the image formation, and the conveying unit does not need to be cleaned before or after the image formation, so that there is no waiting time for cleaning. In particular, in an apparatus having a long conveyor belt, the operation time can be reduced.

According to the second aspect of the present invention, the durability of the cleaning means and the transfer material conveying belt is increased because the cleaning means only needs to operate during image formation.

According to a third aspect of the present invention, in the first aspect, after the image formation is completed, the charge elimination means stops its operation after the conveyance device is stopped. It can be prevented from remaining.

According to a fourth aspect of the present invention, the transport device includes an endless flexible belt, and the first aspect is applicable.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a first embodiment of the present invention.

FIG. 2 is a flowchart of the first embodiment of the present invention.

FIG. 3 is a timing chart according to the first embodiment of the present invention.

FIG. 4 is a longitudinal sectional view illustrating a second embodiment of the present invention.

FIG. 5 is a flowchart of a second embodiment of the present invention.

[Explanation of symbols]

 1. Photosensitive drum 2. Primary charging device 3. Scanning optical device 4. Developing device 5. Cleaning device 6. Conveyor belt 7. Transfer charger 8. Fixing device 12. Test pattern reading device 24 transfer material discharge port 30 copying machine main body 60 transfer material transport device 90 cleaning means 91 frame 92 fur brush 94 conductive brush

Continued on the front page (72) Inventor Takeshi Fujita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yoshihiro Murasawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masami Izumizaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Koji Amemiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Nobunatsu Sasanuma 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-253080 (JP, A) JP-A-63-163480 (JP, A) JP-A Sho 63-132276 (JP, A) JP-A-1-154075 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 21/14

Claims (4)

(57) [Claims] 1. An image forming section provided with an image carrier on which a visible image is formed, and adjacent to the image carrier, the transfer of the visible image while carrying and transporting a transfer material by electrostatic attraction. A transport device having a transfer material transport belt that passes through the position, and a cleaning unit that cleans the transport belt , wherein the transfer material is separated in the moving direction of the transport belt.
Upstream of the downstream and the cleaning unit position, and the image forming apparatus characterized by providing the respective charge removing means downstream of the upstream and the cleaning means of the image forming unit. 2. The image forming apparatus according to claim 1, wherein the cleaning unit operates during image formation. 3. The image forming apparatus according to claim 1, wherein, after completion of image formation, the charge elimination unit stops operating after the conveyance belt stops. 4. The image forming apparatus according to claim 1, wherein the transfer device includes an endless flexible belt as the transfer material transfer belt.