JPH06130775A - Color image forming device - Google Patents

Abstract

PURPOSE:To prolong the life of a transfer belt, to enhance the detection precision of a position and to reduce a fault by constituting a color image forming device for attaching a light reflector for detecting the position on the surface of a transfer belt and covering the optical reflector with a transparent member. CONSTITUTION:For positioning the transfer belt 70 at the time of transferring the different color toner images of yellow, magenta and cyan, a reflection sheet 71 attached to a fixed position on the transfer belt 70 is used. The surface of the reflection sheet 71 provided on the transfer belt 70 is covered with the covering layer 72 of the transparent material. When the transfer belt 70 is sent to transfer rollers 7a-7c and the reflection sheet 71 approaches a position detecting point, first, the covering layer 72 is cleaned by a sheet cleaner 75. When the reflection sheet 71 reaches the position detecting point, light L projected from a projector 73 is reflected by the reflection sheet 71. Further, the reflected light L is received by a photodetector 74 and the position of the transfer belt 70 is detected to transfer the toner images of each different color.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming method in which toner images of different colors successively developed on a photosensitive member are once transferred and superposed on a transfer belt, and the mixed color toner images are transferred again to a sheet. Regarding the device.

[0002]

2. Description of the Related Art The structure of a color image forming apparatus differs depending on the method of superposing multicolor toner images formed on a photoconductor, and several methods have been proposed. The places where different toner images are superposed according to the method are roughly classified into a cylindrical drum of a dielectric film, a high-resistance belt, and a photoconductor. Each has its own unique characteristics.

FIG. 3 is an explanatory view of the structure of a conventional color image forming apparatus, FIG. 4 is a perspective view of a transfer belt of the conventional color image forming apparatus, and FIG. 5 is a sectional view taken along line AA of FIG. In FIG. 3, 1 is a main body of a conventional color image forming apparatus, 2 is a photoconductor, 2a and 2b are photoconductor rollers, 3 is a corona charger,
4, 5 and 6 are developing machines. The developing machines 4, 5 and 6 store yellow, magenta and cyan toners, respectively. 7 is a transfer belt, 7a to 7c are transfer rollers, and 8
Is a belt cleaner, and 9 is a discharge lamp. The structure of the transfer belt 7 is shown in FIG. 4, and the sectional view of the transfer belt 7 is shown in an enlarged scale in FIG. The transfer belt 7 is wound around three rollers 7a to 7c, and the photosensitive member 2 fed along the roller 2a is suspended between the rollers 7a and 7c while being pressed into contact therewith.

The transfer belt 7 is made of a material which is flexible and capable of being removed and charged. Generally, polycarbonate in which carbon particles are dispersedly mixed is used. 4 and 5, 7d is a through hole for position detection, and 7e is a rail. The through hole 7d transmits the detection light L to position the transfer belt 7 and superimpose and transfer the toner images of different colors on the same position. The rails 7e are provided on both sides of the inner surface of the transfer belt 7 and have a function of preventing the transfer belt 7 from meandering.

Numerals 10 and 11 designate first and second transfer chargers, 1
Reference numeral 2 is a peeling charger, and 13 is a charge eliminating charger, which are provided around the transfer belt 7. Reference numeral 14 is a paper feed section provided on the right side of the main body 1, and 15 and 16 are paper feed cassettes.
Reference numeral 17 is a fixing unit on the left side of the main body 1, and 18 is a paper discharge unit. Further, 20 is an optical system, 21 is a light source, 22 to 26 are mirrors,
27 is a lens, 28 is a color separation filter, 29 is a document table,
Reference numeral 30 is a color original. The optical system 20 scans the original 30 and guides the reflected light to the exposure point P of the photoconductor 2. Further, the color separation filter 28 sequentially switches light of each color of blue, green, and red and transmits the light.

The operation of the conventional device having such a configuration will be described below. First, the optical system 20 scans the color original 30, and only the blue light is transmitted by the color separation filter 28 to expose the exposure point P of the photoconductor 2. As a result, a latent image having blue information is formed, and yellow toner is attached by the developing device 4 to develop the toner image. The yellow toner image attached to the photoconductor 2 is temporarily transferred to the transfer belt 7 by the first transfer charger 10. Similarly, only the green and red lights are sequentially transmitted by the color separation filter 28 to form magenta and cyan toner images on the photoconductor 2. The formed magenta and cyan toner images are successively transferred to the same position on the transfer belt 7 in an overlapping manner.

The mixed-color toner images transferred and superposed on the transfer belt 7 are transferred to the papers fed from the paper feed cassettes 15 and 16 of the paper feed unit 14 and fixed by the fixing unit 17, and then the paper discharge unit. The paper is discharged from 18. The transfer belt 7 that has been transferred to the paper is sent to the belt cleaner 8 for cleaning. In this way, the same color image as on the original 30 placed on the original table 29 is formed on the paper.

In this case, as described above, the conventional transfer belt 7 uses a belt-shaped resin material in which the through holes 7d for position detection are provided and carbon particles are mixed. A part of the transfer belt 7 is pressed against the roller 2a of the photoconductor 2 from the outside, and the inside of the transfer belt 7 is fed along the three rollers 7a to 7c while being constantly tensioned. For this reason, the transfer belt 7 must be replaced at the time of regular maintenance / inspection when internal strain occurs due to tension and a certain period of use is exceeded. The life of this type of transfer belt is tens of thousands of rotations statistically, and it is estimated that it is about 20,000 sheets when it is estimated to be a color copy of the paper in the A-row, No. 4 sheet.

[0009]

As described above, the conventional transfer belt 7 is designed to be replaced at regular intervals because of its life. The main factor that determines the life of the transfer belt 7 is not only the material of the material but also the cracks and cutting by the through holes 7d for position detection. If a crack is formed in the portion of the through hole 7d, the transfer belt 7 is slackened, resulting in misalignment and insufficient transfer of the toner image. On the other hand, a transfer mechanism such as the first and second transfer chargers 10 and 11 and a paper feed mechanism of the paper feed unit 14 are provided near the transfer belt 7 to complicate the structure. Therefore, the replacement of the transfer belt 7 is carried out by a dedicated maintenance staff member, so that the replacement and the subsequent inspection work take time, resulting in waste of time and uneconomical problems.

The present invention has been made to solve the above problems of the conventional apparatus. The life of the transfer belt is extended to prolong the replacement cycle, and the position detection accuracy is improved to perform color matching. It is an object of the present invention to realize an economical color image forming apparatus which is good and has few failures.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a photosensitive member which sequentially develops toner images of different colors by attaching toners of respective colors to a latent image formed by irradiating a color-separated light beam by a developing machine. In a color image forming apparatus provided with a transfer belt made of a synthetic resin that transfers the toner images of different colors that have been developed while being positioned by pressing a part of the outer periphery of the photoconductor, the transfer belt is positioned on the surface of the transfer belt. This is a color image forming apparatus in which a light reflector for detection is attached and covered with a transparent member.

[0012]

The positioning of the transfer belt during the transfer of toner images of different colors of yellow, magenta, and cyan on the photoreceptor, which are successively developed by the developing machine, is performed by a reflection sheet attached at a predetermined position on the transfer belt. Is used. The surface of the reflection sheet provided on the transfer belt is covered with a thin layer of a transparent material.

[0013]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration explanatory view of a main part of an embodiment of the present invention, and FIG. 2 is a sectional view of a transfer belt according to the embodiment of the present invention. In FIG. 1, 70 is a transfer belt according to the embodiment of the present invention. Reference numeral 71 is a reflection sheet for detecting the position of the transfer belt 70, and 72 is a coating layer. The reflection sheet 71 is made of, for example, a thin rectangular aluminum thin plate, and the surface thereof is polished to increase the reflectance. Then, the transfer belt 70 is adhered to the position corresponding to the through hole 7d of the conventional device with an adhesive, and a non-affinity transparent covering layer 72 of, for example, Teflon (trade name) is formed on the transparent belt. Reference numeral 73 is a light projector, 74 is a light receiver, and 75 is a sheet cleaner. Further, 81 is a blade made of urethane rubber or the like provided on the belt cleaner 8, and Q is a position detection point of the transfer belt 7. The other structure is the same as the conventional device.

In the embodiment of the present invention having such a structure,
Similarly to the above, the color original image is color-separated into blue (B ... blue), green (G ... green), and red (R ... red),
The yellow, magenta, and cyan toners of the developing device are successively attached to the latent images formed on the exposed points of the photoconductor to develop the latent images. The developed toner images are sequentially transferred and superposed on the transfer belt.

In the present invention, a reflective sheet 71 attached at a predetermined position on the transfer belt 70 is used for positioning the transfer belt 70 when transferring the toner images of yellow, magenta and cyan colors. The surface of the reflection sheet 71 provided on the transfer belt 70 is covered with a coating layer 72 made of a transparent material. When the transfer belt 70 is sent to the transfer rollers 7a to 7c and the reflection sheet 71 approaches the position detection point Q, the coating layer 72 is first cleaned by the sheet cleaner 75. When the reflection sheet 71 reaches the position detection point Q, the light L projected from the projector 73 is reflected by the reflection sheet 71. The reflected light L is received by the light receiver 74, the position of the transfer belt 70 is detected, and the toner image of each color is transferred.

In this way, the reflection sheet 71 accurately positions the toner image of each color, and the transfer belt 70
It is transferred to the same position on the upper part with good color matching. The mixed-color toner image is re-transferred to the paper fed from the paper feeding unit 14 and then fixed by the fixing unit 17, and the paper discharging unit 1
The sheet is discharged from the sheet 8 (see FIG. 3).

At this time, since the reflection sheet 71 is covered with the non-affinity coating layer 72, adhesion of not only toner but also dust is prevented. Moreover, the transfer belt 70 is sent and the reflection sheet 71 is cleaned by the sheet cleaner 75 immediately before reaching the position detection point Q. As a result, even if foreign matter is attached to the coating layer 72, it is removed by the contacting sheet cleaner 75. Also,
Since the reflection type position detecting means using the reflection sheet is used instead of the transmission type using the through holes, the life of the transfer belt 70 is significantly extended.

In the above-described embodiment of the present invention, the case where three color toners are superposed and transferred is described as an example, but the present invention is also applicable to the case where three or more color toners are superposed one after another. Can be applied. In addition to ordinary white light as a light source for exposing a latent image, a light beam from a light source such as a laser oscillator or an LED array can be used. Further, the light for detecting the position of the transfer belt is reflected by the reflection sheet of the aluminum rectangular thin plate, but the material and shape are not necessarily limited to the embodiment as long as it is a reflector that reflects the light.

[0019]

According to the present invention, there are provided a photoconductor in which a toner image of each color is sequentially developed by adhering toner of each color to a latent image formed by irradiation of a color-separated light beam by a developing machine, and a photoconductor. In a color image forming apparatus equipped with a transfer belt made of a synthetic resin that transfers toner images of different colors that have been developed while being positioned by pressing a part of the outer periphery under pressure, a light for position detection on the surface of the transfer belt. A color image forming apparatus having a reflector attached and covered with a transparent member was constructed.

As a result, unlike the conventional transfer belt, there are no cracks or cuts due to the through holes, and the transfer belt is not loosened and misaligned or the toner image is not sufficiently transferred. Therefore, the time for replacement and inspection work becomes unnecessary without bothering the dedicated maintenance personnel for replacing the transfer belt. In particular, if the reflective sheet is coated with a non-affinitive substance as in the example, the adhesion of dust is eliminated,
Maintenance work is easy and copy accuracy can be improved. Therefore, according to the present invention, it is possible to realize a color image forming apparatus having excellent image reproducibility and a high operating rate.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a main part of an embodiment of the present invention.

FIG. 2 is a sectional view of a transfer belt according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a conventional color image forming apparatus.

FIG. 4 is a perspective view of a transfer belt of a conventional color image forming apparatus.

5 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

 2 Photoconductors 7a to 7c Transfer roller 8 Belt cleaner 7e Rail 10 First transfer charger 11 Second transfer charger 12 Peeling charger 13 Static eliminator charger 14 Belt cleaner 15 Paper feed unit 17 Fixing unit 18 Paper ejection unit 20 Optical system 21 Light Source 28 Color Separation Filter 30 Color Document 70 Transfer Belt 71 Reflective Sheet 72 Covering Layer 73 Emitter 74 Light Receiver 75 Sheet Cleaner 81 Blade Q Position Detection Point

Claims (1)

[Claims] 1. A photoconductor for sequentially developing a toner image for each color by adhering toners of respective colors to a latent image formed by irradiating a color-separated light beam by a developing machine, and a peripheral portion of the photoconductor. In a color image forming apparatus including a transfer belt made of a synthetic resin that transfers the developed toner images of different colors while being pressed against each other and positioned, a light reflection for position detection on the surface of the transfer belt. A color image forming apparatus having a body attached and covered with a transparent member.