JPH02178680A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a stable image with an excellent quality by having a control mode where an image carrier and a carrying means are brought into contact with each other and are driven at different peripheral velocities when they do not perform image transfer. CONSTITUTION:The part to where an abrasive material 50 is applied i provided on the part of a carrying belt 8. The device has the control mode, that is, an abrasive mode where the carrying belt and a photosensitive drum are brought into contact with each other at different peripheral velocities except when an image is transferred. Thus, the timing of carrying a transfer material in a normal image forming mode except the abrasive mode is controlled to prevent the position of the abrasive part on the carrying belt from overlapping with the position of transfer material absorption at the time of image transfer. In addition, the abrasive mode where the carrier belt 8 and the photosensitive drum are brought into contact with each other can be set and performed during the warming-up time. Therefore, a high quality image free from irregularities can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus that forms an image on an image carrier and transfers the image to a transfer material conveyed by a conveyance means. Suitable for application to color electrophotographic image forming apparatuses, particularly color electrophotographic copying apparatuses that form images of a plurality of different colors on an image bearing member such as an electrophotographic photoreceptor, and sequentially transfer the images onto the same transfer material. It is possible.

LL's [Conventionally, an image-forming r& device is equipped with a plurality of image forming sections, each of which forms toner images of different colors, and sequentially transfers the toner images onto the same transfer material, so-called color. Although various image type rIt devices have been proposed, the most widely used color copying device is a color copying device using a multicolor electrophotographic method.

An example of such a color electrophotographic copying apparatus will be briefly described based on FIG. Second. Third and fourth image forming sections Pa, Pb
, Pc and Pd are arranged in parallel 0M image forming fiPa, P
b, Pc, and Pd each have a dedicated image carrier, in this example, electrophotographic photosensitive drums la, lb, lc, and ld.

The photosensitive drums la, lb, lc, and ld have latent image forming portions 2a, 2b, 2c, 2d, development flB3a, and
3b, 3c, 3d, transfer discharge tf & 4a, 4b, 4c
, 4d and cleaning sections 5a, 5b, 5c, and 5d are arranged.

In a certain configuration, first, the photosensitive drum l of the first image forming section Pa is
A WI image of the yellow component color in the original image is formed by the latent image forming section 2a on the image a. The latent image is formed into a visual image by a developer containing yellow toner in the developing section 3a, and the yellow toner image is transferred onto the transfer material 6 at the transfer section 4a.

On the other hand, while the yellow image is being transferred to the transfer material as shown in L, a latent image of the magenta component color is formed in the second image forming section Pb, and then the magenta toner image is formed in the developing section 3b as described above. When the transfer material 6 that has been transferred at the first image forming section Pa is carried into the transfer section 4b, the image is transferred to a predetermined position on the transfer material 6.

Hereinafter, the third step will be carried out in the same manner as above. Fourth image forming section P
Cyan and black images are formed using cyan and Pd, and the cyan and black colors are transferred to predetermined positions on the same transfer material.

When such an image forming process is completed, the transferred Murakami image is fixed on the transfer material in the fixing section 7, and a multicolor image is obtained. On the other hand, each photosensitive drum la, lb, lc after the transfer has been completed.
, ld have residual toner removed by cleaning sections 5a, 5b, 5c, and 5d, and are ready for the next latent image formation to be performed subsequently.

In the image forming apparatus having the above configuration, the transfer material 6 is transported by the transport belt 8 from the right side to the left side in FIG.
The transfer portions 4a, 4b, and 4C14d are configured to pass through the transfer portions 4a, 4b, and 4C14d.

Incidentally, in the above image forming apparatus, a Se, 5e-TehA photoreceptor or an OPC photoreceptor is generally used as an image carrier.

Among these, in the case of Se-based photoreceptors, ozone, which is generated as a secondary product during corona discharge used for surface charging, adheres to the surface of the photoreceptor as the photoreceptor is used for a long time. This attached ozone adsorbs water molecules in the air well, and therefore the surface resistance of the photoreceptor surface is reduced by adsorption of these water molecules. This causes the problem of leakage of charged charges toward the surface, which manifests itself in actual images as a phenomenon called "image blur" in which the edges of the image are severely distorted.

On the other hand, with regard to OPC photoreceptors, in addition to the above-mentioned phenomenon, some of the filler contained in paper, which is widely used as a transfer material, is attached to the surface of the photoreceptor during transfer, or is spread over the entire surface with a cleaning blade etc., making it thin. It also happens that the photoreceptor becomes a film and covers the surface of the photoreceptor. Similar to the case of the thin film mentioned above, this film is very susceptible to moisture absorption, and as a result, it promotes the occurrence of similar image blurring.

As a solution to these problems, there are two methods: one is to incorporate a roller to polish the surface of the photoconductor into the cleaning device and constantly polish the surface of the photoconductor, and the other is to remove the photoconductor from the main body of the machine after a certain period of time and polish the surface with an abrasive. A commonly used method is to scrape off a thin layer on the surface.

However, the color electrophotographic copying machine with the above-mentioned configuration requires multiple photosensitive drums, and incorporating the above-mentioned abrasive rollers in each cleaning device increases costs. The method of removing and polishing requires more than four times as much time as the conventional black and white method.

Therefore, an object of the present invention is to solve the above problems, and to obtain images of stable and good quality by changing some of the conventional components without installing complicated and expensive mechanisms. An object of the present invention is to provide an image forming apparatus that can perform the following steps.

The above object is achieved by an image forming apparatus according to the present invention.

To summarize, the present invention provides an image forming apparatus that forms an image on an image carrier and transfers the image to a transfer material conveyed by a conveyance means.

The image forming apparatus is characterized in that it has a control mode in which the image carrier and the conveying means are driven in contact with each other at different circumferential speeds when one image is not transferred.

Preferably, a member suitable for polishing the surface of the image carrier is attached to a part of the conveyance means and on the side that comes into contact with the image carrier.

Further, the circumferential speed of the image carrier and the conveying means in the drive control mode is set such that the entire surface of the image carrier passes while the abrasive portion of the conveying means is in contact with the image carrier. ing.

L difference j Next, one embodiment of the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Referring to FIG. 2, the present invention is embodied in a color electrophotographic reproduction apparatus similar to that described in connection with FIG.

That is, in this embodiment, the image forming apparatus according to the present invention is
9d Image forms TItfl P a , Pb in the main body 10
. Rotated in the direction of the arrow.

A paper feed mechanism 13 is arranged on the right side of the conveyor belt 8 in FIG.
sent to the top. Each image forming section Pa, Pb, Pc, P
The transfer material 6 whose transfer has been completed in step d is sent to the fixing device 7 from the left side of the conveyor belt 8. The fixed transfer material 6 is discharged from the discharge port 14 to the outside of the apparatus main body 10.

The first... 2nd degree The third and fourth image forming sections Pa, Pb, Pc, and Pd have photosensitive drums la, 1b, IC, and 1d, and the photosensitive drums la,
Chargers 15a, 15b, 15C, and 15d are provided on the left side of the No. 1 section of lb, IC, and ld, respectively.

Further, the photosensitive drums la, lb, lc, and ld are exposed to upper laser beams 16a, 16b, and 16c.

16d are arranged respectively. These laser beam scanners lea, 16b, 16c, and lad consist of semiconductor lasers, polygon mirrors, fO lenses, etc., and receive input of electric digital image signals.

Charge a modulated laser beam in response to that signal!
! 15a, 15b, 15c, 15d and developer leakage 3a, 3b
, 3c, 3d, the photosensitive drums la, lb, lc, l
It is formed to scan in the direction of the generatrix d and to mist these.

To explain in detail, the laser scanner 1 of the first image forming section Pa
6a, a pixel signal corresponding to the yellow component image of the color image is transmitted to the laser scanner 16b of the second image forming section pb.
Pixel signals corresponding to magenta component images are respectively input to the laser scanner lee of the first image forming section IIt Pc and the laser scanner 1 of the fourth image forming section Pd.
In 6d.

A pixel signal corresponding to a cyan component image and a pixel signal corresponding to a black component image are respectively input.

The paper feeding mechanism 13 includes a paper feeding guide 51 and a sensor 52. When the transfer material 6 is inserted into the paper feeding guide 51, the sensor 52 detects the tip of the transfer material 6, and the photosensitive drums la, lb are detected.
, lc, ld, and at the same time sends a rotation start signal to drive rollers 11, 13. '76 is also driven to rotate the conveyor belt 8. Further, the transfer material 6 fed to the conveyor belt receives corona discharge from the attraction chargers 59 and 62, and is reliably attracted to the surface of the conveyor belt 8. In this embodiment, the adsorption charger 59.6
The polarities of the two high voltages are set to be opposite to each other, and the charger 62 has the same polarity as the transfer chargers 4a, 4b, 4c, and 4d.

The leading edge of the transfer paper 6 is connected to each sensor Boa, 60b, 60c,
When the signal 60d is shut off, image formation on the rotating photosensitive drums la, lb, lc, and ld is sequentially monitored based on the signal. When the transfer material 6 passes through the fourth image forming section Pd,
The transfer material 6 is neutralized by a static eliminator 61 to which an AC voltage is applied, and is separated from the conveyor belt 8 .

Next, the transfer material 6 enters the fixing device 7 to fix the image, and then is discharged from the discharge port 14.

Further, according to the present invention, as shown in FIG. 1, a part of the conveyor belt 8 is provided with an abrasive agent 50, so that it does not touch the photosensitive drum at any time other than during image transfer. A control mode, ie, a polishing mode, is provided in which the conveyor belt and the photosensitive drum are driven in contact with each other at different circumferential speeds. Therefore, the conveyance timing of the transfer material in the normal image forming mode other than the polishing mode is controlled so that the position of the polishing portion of the conveyance belt L does not overlap with the transfer material suction position during one image transfer.

To explain further, the abrasive part of the m-transfer belt 8 is coated with an abrasive 50 equivalent to waterproof paper #600 with a width of 50 mm and a thickness of approximately 10 mm.
It can be applied to a thickness of about 0 μm.

Further, the polishing mode in which the conveyor belt 8 and the photosensitive drum come into contact does not need to be performed every time copying is performed, for example, every morning.
It can be set and executed until the surface temperature of the fixing device rises to a predetermined level when the main switch of the copying device is turned on, that is, during the warming-up period.

In this polishing mode, the photosensitive drums la, lb, 1c, 1d
The peripheral speed is the same as during normal image formation (for example, 85 m
m/s), but if the photosensitive drum diameter is 60 mm, the peripheral speed of the conveyor belt 8 is approximately 22.6 mm.
/s. At this circumferential speed, the entire circumference of the photosensitive drum rotates once while the abrasive part 50 passes the photosensitive drum contact position, and the entire surface of the photosensitive drum is covered by the abrasive part 5 of the conveyor belt.
0 will be contacted.

According to the results of research and experiments conducted by the present inventors, it has been confirmed that image deletion can be completely prevented by executing the polishing mode according to the present invention.

In other words, according to the image forming apparatus with the conventional configuration, image blurring occurred after approximately 2,000 sheets in a high temperature, high humidity environment (30°C, 90% RH). It was found that this phenomenon did not occur even after forming 10,000 images, which is the lifespan of the human body.

Another embodiment of the present invention is shown in FIG. 3. In the color electrophotographic copying apparatus of this embodiment, latent images such as a pre-exposure 21, a corona charger 15, an image exposure 17, etc. are formed on the photosensitive drum l. A color separation latent image is formed by the forming means, and a color separation latent image is formed by the one-rotation developing device 3.
One image is visualized.

The rotary developing device 213 is configured by mounting a yellow developing device 3Y, a magenta developing device 3M, a cyan developing device 3C1, and a black developing device 3B, which have developers of different colors, on a rotationally movable rotary body. A developing device of a color corresponding to the color-separated latent image selectively stops rotating at a developed image facing the photosensitive drum 1 to develop a color-separated Ns image.

The developed image is transferred by a transfer corona discharger 4 onto a transfer material 6 held by a gripper portion 26 placed on the surface of the transfer drum 20. Toner remaining on the surface of the photosensitive drum 1 without being transferred is cleaned by a cleaner (cleaning means) 5 having a blade 5a. After the four-color development and image are aligned and transferred onto the transfer material 6, the transfer material 6 is separated from the transfer drum by a separating claw 22, guided to a fixing device (not shown), and fixed to form a full-color image. can get.

According to the present invention, the transfer drum 6 is formed with an abrasive portion 50 similar to the embodiment described in t. Preferably, the gripper portion 26
It will be installed at a position corresponding to .

Also, in the copying apparatus of this embodiment, a polishing mode is incorporated in the same manner as in the previous embodiment.

As a result of research experiments conducted by the present inventor, it was confirmed that the image forming apparatus of this example also sufficiently exhibits the effect of preventing image blurring.

11 Rikuo] The image forming unit 921 according to the present invention configured as described above can prevent image fading caused by water supply substances adhering to the surface of the image bearing member, and at the same time, it is possible to prevent the image bearing member from being used for a long period of time. It has the advantage of being able to obtain high-quality images without blurring.

Further, the image forming apparatus of the present invention can obtain the above-mentioned effects with a simple configuration, and can achieve the same effects as conventional ones! 2t can be easily modified and applied.

It has the advantage of being extremely convenient and highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conveyor belt constructed in accordance with the present invention. FIG. 2 is a sectional view of an embodiment of an image forming apparatus according to the present invention. FIG. 3 is a sectional view of another embodiment of the image forming apparatus according to the present invention. FIG. 4 is a sectional view of a conventional image forming apparatus. l: Image carrier 6: Transfer drum 8: Conveyor belt 50: Grinding I9! Part diagram 2

Claims (1)

[Claims] 1) In an image forming apparatus that forms an image on an image carrier and transfers the image to a transfer material conveyed by a conveying means, the image bearing member and the conveying means perform image transfer. An image forming apparatus characterized by having a control mode in which contact driving is performed at mutually different circumferential speeds when the image forming apparatus is not in use.