JPH0519641A - Multiple image forming device - Google Patents

Abstract

PURPOSE:To prevent an image carrier from being damaged because of friction by separating a transfer material carrying means from the image carrier after an image on the image carrier is transferred on a transfer material. CONSTITUTION:When the transfer paper is fed from a paper feeding cassette 7, abutting members 10MA, 10CA, 10YA and 10KA are actuated so that a transfer belt 6a being a moving body, which is separated from photosensitive drums 1M, 1C, 1Y and 1K being the image carrier at the beginning, is allowed to abut on them. Next, the transfer belt 6a and the photosensitive drums 1M, 1C, 1Y and 1K simultaneously start to rotate to execute image forming actions. When transfer is finished, the members 10MA, 10CA, 10YA and 10KA are separated, and the transfer belt 6a is separated from the photosensitive drums 1M, 1C, 1Y and 1K. Then, the rotation of the photosensitive drums 1M, 1C, 1Y and 1K is stopped after the drums 1M, 1C, 1Y and 1K are destaticized with uniform light by a scanning optical device. On the other hand, the transfer belt 6a is stopped after cleaning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming station having image forming means around an image carrier.
The present invention relates to a plurality of image forming apparatuses.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a laser beam printer having a plurality of optical scanning means to which the present invention is applicable.
A laser beam printer having one image forming station outputs an image according to a color separation signal of an original image from an image reader (not shown).

This printer is provided with four image forming stations around an image carrier, which is an electrophotographic photosensitive member, which is provided with image forming means which is a conventional electrophotographic process. The image formed on the image carrier is transferred to a transfer material that is carried and carried by a belt-shaped moving body that moves in contact with the image carrier.

Photosensitive drums 1M, 1C, 1Y and 1K are arranged on the image forming stations Pm, Pc, Py and Pk for magenta, cyan, yellow and black, respectively, and are rotated in the arrow direction (clockwise direction). . Around the photosensitive drums 1M, 1C, 1Y and 1K, corona chargers 2M, 2C, 2Y and 2K, laser beam scanning optical devices 3M, 3C, 3Y and 3K, developing devices 4M, 4C, 4Y, 4K, cleaning device 5M,
An image forming unit composed of 5C, 5Y and 5K is provided.

Further, the transfer section 6 which constitutes one of the image forming means includes an endless belt 6a which is a transfer material conveying means common to each image forming station and a transfer corona charger 6M,
The formation of a full-color image having 6C, 6Y, and 6K is achieved by sequentially transferring the toner images of the respective colors formed on the photosensitive drum onto the transfer material P supported on the transfer belt 6a. The transfer belt 6a is brought into contact with the photosensitive drum by pressing members 10M, 10C, 10Y, and 10K made of elastic sheets.

The transfer material P is supplied from the paper feed cassette 7,
The transfer material P that has completed the transfer process is forcibly separated and reaches the tray 9 via the fixing device 8.

The scanning optical devices 3M, 3C, 3Y, 3K
Is a laser device (not shown), a rotating polygon mirror for scanning the laser device, an fθ lens for condensing the scanning beam on the generatrix of the surface of the photosensitive drum, a reflecting mirror for deflecting the light beam, and the scanning. And a beam detection device for detecting a specific position of the beam.

The operation timing of image formation in such an image forming apparatus is shown in the timing chart of FIG.

In the figure, "1" is an operating state and "0"
Indicates a non-operating state. In such an apparatus, when the copying is started, the photosensitive drums of the respective stations are sequentially stopped after the image formation and the transfer of the image to the transfer material are completed in order to prevent the unnecessary rotation from being sequentially rotated from the first image station. It is possible to do it. on the other hand,
When the copying operation is started, the transfer belt 6a operates while conveying the transfer material until the entire transfer process is completed.

In such an operation, one of the photosensitive drum and the transfer belt is stopped and the other is operating. The transfer belt 6a is in contact with the photosensitive drums 1M, 1C, 1Y, 1K by the pressing members 10M, 10C, 10Y, 10K, respectively, so if only one of them is stopped, it is rubbed,
Either the photosensitive drum, the transfer belt, or both are damaged, resulting in deterioration of image quality.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, prevent damage to the image carrier and further the transfer material, and enable stable formation of high quality images. Is provided.

[0012]

The present invention to achieve the above object is a multiple image forming apparatus for forming multiple images by sequentially transferring images formed on a plurality of image stations having a carrier to a transfer material. There are a plurality of image forming stations arranged in the conveying direction of the transfer material, a transfer means for transferring the image formed on each image forming station to the transfer material, and an endless movement to transfer the transfer material to the transfer portion of each image forming station. And a transfer material transporting means for transporting the transfer material, a transfer material transporting means for moving the transfer material transporting means to and from the image carrier of the image forming station, and the transfer material transporting means for forming each image. While in contact with the image carrier of the station, the image carrier and the transfer material conveying means are driven to transfer the image of the image carrier to the transfer material, and then the transfer material conveying means is separated from the image carrier. Those were.

[0013]

【Example】

[Embodiment 1] An embodiment in which the present invention is applied to the apparatus of FIG. 2 will be described in detail with reference to FIG.

FIG. 1 is a time chart showing a copy operation state diagram when the present invention is applied to the apparatus shown in FIG.

Copying is started in FIG.
When the transfer material P is fed from the paper feeding cassette 7 of the apparatus
Pressing member 10MA, 10CA, 10YA, 10KA
And the transfer belt 6a, which is a moving body, comes into contact with the photosensitive drum, which is an image carrier, although it was initially separated. Next, the transfer belt and the photosensitive drum start to rotate at the same time to perform an image forming operation.

After the image formation and transfer in the fourth station, the pressing members 10MA, 10CA, 10YA,
10 KA is separated, and the transfer belt is separated from the photosensitive drum. Next, the photosensitive drums 1M, 1C, 1Y, and 1K are stopped after rotating the photosensitive drums 1M, 1C, 1Y, and 1K after removing the charge with uniform light by the scanning optical device. Cleaning one transfer belt,
After separating from the photosensitive drum, the copying operation is stopped and the copying operation is completed.

As the pressing member in the above embodiment, a metal plate or sheet-like resin provided on a part of the shield plate on the upstream side of the transfer corona discharger 10M, 10C, 10Y, 10K as viewed in the transfer conveyance direction is used. It is composed of a rigid elastic body or a rigid body, and only a pressing member is driven by a driving means (not shown).
Alternatively, this pressing member is moved to the transfer belt side together with the integrated discharge device so as to be pressed against the transfer belt, or released by releasing the pressing member against the belt. Even if only such a pressing member is separated from the belt, the belt and the drum can be prevented from rubbing against each other.

[Embodiment 2] In the first embodiment described above, the case where the transfer belt is brought into contact with the photosensitive drum by the backup member has been described, whereas in FIG. 4, the transfer unit 6 including the transfer belt is indicated by an arrow. A lifter 11 that moves up and down in the direction is provided. Regarding other symbols used, the same members as those in FIG. 2 are denoted by the same reference numerals.

In FIG. 4, the lifter 11 supports the transfer unit 6 and moves the transfer unit 6 up and down by a driving means which will be described later to bring the transfer unit belt 6a into contact with or separate from each photosensitive drum. A copy operation state diagram at this time is shown in the time chart of FIG.

First, the transfer lifter operation is "up",
When the transfer belt and the photosensitive drum are brought into contact with each other, the transfer belt and the photosensitive drum start rotating at the same time, and the image formation as described above is performed. After the image formation and transfer to the transfer material are completed, the charge of the photosensitive drum is removed as described above,
At the same time, it stops its rotation.

After that, the transfer lifter is "down" to complete all copying operations.

Regarding the timing of contact and separation of the photosensitive drum and the conveyor belt, when the driving of both is started from the state where they are in contact with each other as in the above-mentioned embodiment, the speed at the time of rising may be different, and it may be a little. There is concern that a rubbing phenomenon may occur due to the speed difference. An example of improving such a problem will be illustrated below.

First, the first example will be described with reference to FIG.

When the copying operation is started, the photosensitive drum,
When the transfer belts are separated from each other, the operation starts. At this time, from the stopped state to the specified speed v [mm / s
ec] once, the speed may be switched to the speed v, or the speed may be continuously accelerated from 0 (stopped state) to v. Alternatively, it may be rapidly changed from 0 to v. In this way, after both the photosensitive drum and the transfer belt reach the same speed v, the photosensitive drum and the transfer belt are brought into contact with each other to form an image.

As the contact means, as described in the above embodiment,
Either a method using a pressing member or a method in which the transfer unit is moved up and down by a lifter may be used. Further, when the operation is stopped after the copying is completed, the same effect can be obtained even if the photosensitive drum and the transfer belt are separated from each other and then gradually decelerated in the same operating state.

As another example, as shown in FIG. 7, the photosensitive drum and the transfer belt may be brought into contact with or separated from each other during the acceleration from the stopped state described in FIG. 6 to a predetermined low speed v. .. Also at this time, the photosensitive drum and the transfer belt are operated at the same speed in the contact section.

[Embodiment 3] A case of a transfer unit using a belt that operates independently for each station, instead of a transfer belt that moves and passes adjacent to each image forming station as in the above embodiment 8 and FIG. 9.

In FIG. 8, 6MB, 6CB, 6YB,
6BB is a transfer unit in each image forming station. Other parts are the same as in FIG. Here, the case of forming only one output image will be described below.

First, the rotation of the first station and the first transfer unit is started, image formation and transfer to the transfer material P are started, and as the leading edge of the transfer material enters the second station, the second station is started. And the second transfer unit rotates. When the transfer in the first station is finished, the rotation of the photosensitive drum and the transfer belt in the first station is stopped after the charge is removed. Similarly, the operation is sequentially started for the second, third, and fourth stations and then sequentially ended. The contact and separation means for the photosensitive drum and the transfer belt 6a may be either the pressing member described in the first embodiment or the lifter of the transfer unit described in the second embodiment.

Next, a concrete example of the contacting / separating mechanism of the transfer material conveying device in the device described in FIG. 4 or 8 is shown in FIG.
13 to FIG. 13 will be described.

First, in the apparatus shown in FIG. 4, as shown in FIGS. 10 and 11, the lifter frame 40 supporting the transfer belt 6a is lifted and lowered. Specifically, the lifter frame 40 is supported by 20, 41 provided on the lifter frame 40, and can be pulled out to the front in the drawing in the lowered state. The lifter frame 40 is supported by a cam 43, and the height of the lifter frame 40 can be changed by rotating the cam shaft 42 to rotate the cam 43 as shown in FIGS. The cam shaft 42 is connected to the position sensor, and it becomes possible to detect the position of the lifter frame 40 based on the signal output state from the position sensor. Further, the cam shaft 42 is connected to a drive source via a clutch mechanism controlled by a microcomputer in the image forming apparatus.

The lifter frame 40, the rollers 41, the cam shaft 42, the cam 43, etc. constitute an elevating means 44 for changing the height position of the transfer unit 6. The elevating means 44 and the transfer unit 6 are set so that the conveyor belt 6a and the surfaces of the photosensitive drums 1M, 1C, 1Y and 1K can contact each other when the conveying means 39 is held at the highest position by the elevating means 44. ing.

Next, regarding the apparatus shown in FIG. 8, the apparatus shown in FIGS.
Follow the instructions below. As shown in the figure, a lift mechanism similar to that shown in FIG. 10 is provided for each station, and by rotating the cam 43, the photosensitive drum and the transfer belt can be brought into and out of contact with each other.

As described above, the image carrier and the transfer material conveying means are brought into contact with each other during the image formation and driven, and before or after the image formation, they are separated from each other, so that the following effects are obtained.

That is, one of them does not stop or rub against each other at different peripheral velocities, so that they are not damaged. Further, since no contact is made during non-image formation, the image carrier may be neutralized before and after the image forming process, and
The process of nd or cleaning can be performed completely independently of the transfer material conveying means. On the contrary, regarding the transfer material conveying means, similarly, it becomes possible to perform the same static elimination and cleaning steps completely independently of the image carrier. Of course, when the same processing steps as those described above are performed, no damage occurs even if they are performed at different peripheral velocities that are appropriate for each other.

[0036]

According to the present invention described above, an image forming apparatus having a plurality of image forming stations is provided, and only one of an image carrier such as a photosensitive drum and a moving body such as a transfer unit or an intermediate transfer medium is used. It is possible to eliminate the operation in the state of touching each other and prevent scratches on the surface of each other and disturbance of the image.

[Brief description of drawings]

FIG. 1 is an operation state diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram of an image forming apparatus embodying the present invention.

FIG. 3 is a conventional operation state diagram.

FIG. 4 is a schematic view of another embodiment.

FIG. 5 is an operation state diagram of another embodiment.

FIG. 6 is an operation state diagram of another embodiment.

FIG. 7 is an operation state diagram of another embodiment.

FIG. 8 is an operation state diagram of another embodiment.

FIG. 9 is an operation state diagram of another embodiment.

FIG. 10 is an explanatory diagram showing a specific drive mechanism of the transfer material conveying means of the apparatus of FIG.

FIG. 11 is an explanatory view showing a specific drive mechanism of the transfer material conveying means of the apparatus of FIG.

12 and 13 are explanatory views showing a specific driving mechanism of the transfer material conveying means of the apparatus of FIG.

FIGS. 12 and 13 are explanatory views showing a specific drive mechanism of the transfer material conveying means of the apparatus of FIG.

[Explanation of symbols]

 1M, 1C, 1Y, 1K Photosensitive drum 6 Transfer unit 6a Transfer belt 40 Lifter frame 41 Roller 42 Cam shaft 43 Cam 44 Lifting means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location B41J 3/54 9110-2C 11/42 Z 9011-2C G03G 15/00 301 8004-2H 15/01 114 Z 7818-2H

Claims (1)

Claims: What is claimed is: 1. A multi-image forming apparatus for sequentially transferring images formed on a plurality of image stations having a carrier to a transfer material to form a multiple image, wherein the transfer material is conveyed. A plurality of image forming stations arranged in a direction, a transfer means for transferring an image formed on each image forming station onto a transfer material, and a transfer material conveying means for endlessly moving and transferring the transfer material to a transfer portion of each image forming station. And a transfer means for moving the transfer material conveying means, which enables contact and separation of the transfer material conveying means with respect to the image carrier of the image forming station, and the transfer material conveying means contacts the image carrier of each image forming station. While the transfer process of each image carrier is completed, the entire image carrier and the transfer material conveying unit are moved until the transfer process of all the image carriers is completed, regardless of the completion of the transfer process of each image carrier. Transferr And a means for separating the transfer material conveying means from the image carrier after the completion of the process.