JPH05224542A - Cleaning device for transfer belt - Google Patents

Abstract

PURPOSE:To obtain stable color images by executing the cleaning of a transfer belt without damaging the belt over a long period. CONSTITUTION:An elastic material prepd. by kneading a molten fluororesin with fluorine-based rubber is used as a blade member 20 and the blade member 20 is fixed to a thin metallic plate 17 and is pressed to the transfer belt 3 of a color image forming device which forms electrostatic latent images on one or plural photosensitive bodies and develops the electrostatic latent images by toners of different colors, rotates a transfer belt 3 on the other hand, electrostatically attracts recording paper onto the transfer belt 3 and superposed and transferes the latent images on the photosensitive bodies on the recording paper by each of the colors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms an electrostatic latent image on one or more photoconductors, visualizes the electrostatic latent image with toner of different colors, while rotating a transfer belt. The present invention relates to a cleaning device for a transfer belt in a color image forming apparatus that electrostatically adsorbs a recording paper on the transfer belt and superimposes a visible image on the photoconductor onto the recording paper for each color.

[0002]

2. Description of the Related Art Conventionally, as a color copying machine or a color printer using the electrostatographic method, for example, Japanese Patent Application Laid-Open No. 58-1 is available.
98062, JP-A-62-118366, JP-A-6
As disclosed in JP-A-2-186285, 1
Toner images of different colors are sequentially formed on two photoconductors, and the transfer paper is electrostatically adsorbed and carried on a transfer belt that can be moved in and out of the photoconductor at the transfer position and that can reciprocate. The transfer belt is brought into contact with the photoconductor and the transfer paper is conveyed to transfer a toner image of one color. After the transfer of one color is completed, the transfer belt is separated from the photoconductor and double-moved to transfer the transfer paper before the transfer is started. There is known a color image forming apparatus of a superposition transfer system in which toner images of a plurality of colors are aligned and superposed and transferred on the same transfer paper by returning to the position, and fixed to form a color image.

Further, as shown in FIG. 2, there is also known a color copying machine which forms an image with four photoconductors instead of one photoconductor. That is, when the transfer belt 3 driven by the driving pulley 1 and the driven pulley 2 is opposed to the transfer belt 3,
A set of image forming units 5a, 5b, 5c and 5d is arranged. Each of the image forming units 5a to 5d includes an exposure device 6, a photoconductor 7, a charger 8, a developing device 9, a transfer device 10, a cleaning brush 11 and a cleaning blade 12. The photoconductor 7 is uniformly charged by the charger 8, and the exposure device 6 performs image exposure of the document.
An electrostatic latent image is formed on it. In the developing device 9, the toner charged to the opposite polarity to the charge of the electrostatic latent image is brought into contact with the surface of the photoconductor 7 to form a toner image, and the developed toner image is transferred to the paper on the transfer belt 3 in the transfer device 10. After that, the toner remaining on the photoconductor 7 is scraped off from the cleaning brush 11 first, and then the cleaning blade 12 is removed.
A series of image forming cycles are carried out by scraping off with the use of four sets of image forming units 5a-5a.
Color images are formed by sequentially performing 5d.

A dielectric such as a polyester film is used as the transfer belt, and the transfer paper is electrostatically adsorbed by being charged by a charging device. Unnecessary toner adheres to the. That is, since the same amount of toner as the blank area adheres to the photoconductor between the image areas on the transfer belt, they will be transferred onto the transfer belt if the transfer corotron is operating. Further, if the paper is not fed or a jam occurs, the visible image on the photoconductor will be directly on the transfer belt. Further, in the color copying machine shown in FIG. 3, in order to correct the image disturbance due to the relative speed deviation between the transfer belt 3 and the photoconductor 7 and the image disturbance due to the density change due to the increase / decrease in the amount of toner in the developing device 9, Lines of four colors are directly transferred onto the transfer belt 3 to check the color shift, and square patches for each color are transferred to check the density.
That is, a large amount of toner image is on the transfer belt 3. To remove these toners in one pass,
A cleaning brush 13 and a cleaning blade 14 are provided in contact with the transfer belt 3.

As the cleaning blade 14,
Polyurethane, which has been conventionally used as a cleaning blade material for a photoconductor, is generally used.

[0006]

However, after a long-term test using the cleaning blade 14 made of polyurethane, the transfer belt was found to be 50,000 times.
The transfer belt became cloudy from around the rotation and was scratched. As a result, erroneous detection of toner density and erroneous detection of color misregistration in the axial direction of the transfer belt occur, making it impossible for a color copying machine to obtain stable images for a long period of time.

The present invention solves the above problems by forming an electrostatic latent image on one or more photoconductors and then visualizing the electrostatic latent image with toner of different colors. Cleaning the transfer belt for a long time in a color image forming apparatus that rotates the transfer belt and electrostatically attracts the recording paper onto the transfer belt to transfer the visible image on the photoconductor onto the recording paper for each color. It is an object of the present invention to provide a transfer belt cleaning device that can obtain a stable color image by performing the operation without damaging the entire area.

[0008]

To this end, the transfer belt cleaning apparatus of the present invention forms an electrostatic latent image on one or more photoconductors and develops the electrostatic latent image with toners of different colors. On the other hand, in a color image forming apparatus that rotates the transfer belt, electrostatically attracts the recording paper onto the transfer belt, and superimposes the visible image on the photoconductor onto the recording paper for each color. An elastic body obtained by kneading molten fluororesin with is used as a blade member, and the blade member is fixed to a thin metal plate and brought into contact with the transfer belt.

[0009]

In the present invention, an elastic body made of fluororubber kneaded with a molten fluororesin is fixed to a thin metal plate so that the elastic force can be applied to the metal plate and the cleaning property can also be applied to the elastic body. When an elastic body obtained by kneading a fluorocarbon rubber with a molten fluororesin is used as the blade member, the friction coefficient with respect to the transfer belt is lowered, so that the transfer belt can be prevented from being damaged for a long time.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show an embodiment of a transfer belt cleaning device according to the present invention. FIG. 1A is a schematic configuration diagram, and FIG. The present invention forms an electrostatic latent image on one or a plurality of photoreceptors described in the conventional example, visualizes the electrostatic latent image with toner of different colors, while rotating the transfer belt to transfer the latent image. The present invention is applied to a color image forming apparatus that electrostatically attracts recording paper onto a belt and superimposes and transfers the visible image on the photoconductor for each color onto the recording paper.

In FIG. A, a cleaning brush 13 is provided in contact with the transfer belt 3, and a cleaning blade 15 that faces the drive pulley 1 and contacts the transfer belt 3 from a direction opposite to the rotation direction of the transfer belt 3. Is provided. As shown in FIG. B, the cleaning blade 15 has a support member 16 to which a thin metal plate 17 having a thickness of 2 mm or less is fixed by an adhesive material 18 or bolts 19, and the blade member 20 is attached to the tip of the metal plate 17 by an adhesive material 18. It is fixed by.

As the blade member 20, a fluororesin-based sliding material is used instead of polyurethane. this is,
An elastic body made by mixing molten fluororesin with fluororubber,
As an example, "LURON LE" manufactured by NTN Precision Resins Co., Ltd. was used. Table 1 shows an experimental result in which the friction coefficient of a blade member made of a commonly used polyurethane blade and Ruron LE with respect to a transfer belt was compared.

[0013]

[Table 1]

For the polyurethane blade, two types of hardness were tested, and the test was performed by wiping the surface of the transfer belt made of PET with EPA (ethyl alcohol) and dusting it with toner. The friction coefficient was measured by changing the angle BSA and the load. It was confirmed that when Ruron LE was adopted as the blade member, the coefficient of friction with respect to the transfer belt was lowered.

Next, an aluminum pipe with a diameter of 50 mm is coated with PET.
Wrap (polyethylene terephthalate) film,
Polyurethane blade and Luron LE, set angle 20
Table 2 shows the results of measuring the transmittance of the PET film after the blade and the aluminum pipe around which PET was wound were rotated at a depth of 1.2 mm for 300,000 times.

[0016]

[Table 2]

FIG. 2 shows the roughness traces of the three surfaces shown in Table 2. In this test, the evaluation result of the polyurethane blade is not so bad because it is not a real machine, but in the real machine, various factors that affect the transmittance of the transfer belt, scratches such as toner, carrier, paper dust, dust in the air, etc. Needless to say, the transmittance is adversely affected.

This RURON LE is not without its drawbacks, because its permanent deformation is about 10 times worse than that of polyurethane, and a cleaner without a mechanism for separating and contacting the photosensitive member causes cleaning failure due to insufficient contact pressure due to permanent deformation. Occur. Even a cleaner with a separation / contact mechanism may cause cleaning failure if it is used for a long period of time. Therefore, in the present invention, the rulon LE is adhered to the tip of the thin metal plate 17 so that the metal plate 17 exerts an elastic force and the rulon LE also has the cleaning property.

The transfer belt 3 of PET, the plate member 20 of LURON LE and the cleaning blanc 13 are used.
As a result of an experiment in the color image forming apparatus shown in FIG. 3, a good quality copy image could be obtained without causing toner density erroneous detection and color misregistration erroneous detection of the transfer belt 3 even when the number of rotations exceeded 100,000. .

Needless to say, in a system in which residual toner on the transfer belt can be cleaned only by the cleaning blade without using the cleaning brush, it is not necessary to use the cleaning brush. Further, this blade may be used as a cleaning blade for the photoconductor. In addition to PET, it can be applied to a translucent resin material such as polyvinylidene fluoride.

[0021]

As is apparent from the above description, according to the present invention, an electrostatic latent image is formed on one or more photoconductors,
The electrostatic latent image is visualized with different color toners, while the transfer belt is rotated to electrostatically attract the recording paper onto the transfer belt to record the visualized image on the photoconductor for each color. In a color image forming apparatus for transferring images onto paper, an elastic body obtained by kneading molten fluororesin with fluororubber is used as a blade member,
Since the blade member is fixed to a thin metal plate and brought into contact with the transfer belt, cleaning of the transfer belt can be performed for a long period of time without damaging the transfer belt, so that a stable color image can be obtained.

[Brief description of drawings]

FIG. 1 shows an embodiment of a transfer belt cleaning device according to the present invention, FIG. A is a schematic configuration diagram, and FIG.

FIG. 2 is a diagram for explaining an experimental result in the present invention.

FIG. 3 is a configuration diagram showing an example of an image forming apparatus to which the present invention is applied.

[Explanation of symbols]

3 ... Transfer belt, 13 ... Cleaning brush, 15 ... Cleaning blade, 17 ... Metal plate, 20 ... Blade member

Claims (1)

[Claims] 1. An electrostatic latent image is formed on one or more photoconductors, and the electrostatic latent image is visualized with toners of different colors.
In a color image forming apparatus that rotates the transfer belt, electrostatically attracts the recording paper onto the transfer belt, and transfers the visible image on the photoconductor onto the recording paper for each color in a superimposed manner. A cleaning device for a transfer belt, wherein an elastic body obtained by kneading is used as a blade member, and the blade member is fixed to a thin metal plate and brought into contact with the transfer belt.