JPH0728294A - Color electrophotographic device - Google Patents

Abstract

PURPOSE:To obtain a color electrophotographic device whose structure is simple and maintenance is free. CONSTITUTION:The color electrophotographic device is provided with photosensitive bodies 42, 44. 46 and 48, developing units 58, 60, 62 and 64, electrifiers 50, 52, 54 and 56, four process means forming images on the photoreceptor with each toner of cyan, magenta, yellow and black, respectively, an intermediate transfer means 118 on which a toner image on each photoreceptor is transferred in four different positions and a paper transfer means 120 transferring the image of the intermediate transfer means on a paper sheet and constituted so that each process means is successively actuated one color by one color and each toner image formed on each photoreceptor is superimposed on the intermediate transfer means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a color digital PP.
More specifically, the present invention relates to a color electrophotographic apparatus such as a C or color optical printer, and more particularly to a color electrophotographic apparatus that sequentially forms a toner image for each color and forms a color image on paper or an intermediate transfer member.

[0002]

2. Description of the Related Art In recent years, various types of color electrophotographic apparatuses have been proposed or commercialized.

Among them, a method of sequentially forming a toner image for each color has been proposed as a method which can be realized at a relatively low speed but at a low cost (hereinafter, referred to as a field sequential method. Corresponding to this) A method capable of simultaneously forming four color toner images at high speed is called a tandem method.)

An example of the conventional frame sequential color electrophotographic apparatus described above will be described below with reference to the drawings.

In FIG. 2, reference numeral 2 is a photoconductor. A charger 4 uniformly charges the photosensitive member 2. Reference numeral 6 is a laser scanner, 8 is a laser drive circuit for operating the laser scanner 6 according to image information, and 9 is an image signal circuit having a function of generating an image signal or transferring the signal. By these, the photoconductor 2 is irradiated with light according to image information to form a latent image. Reference numeral 10 denotes a developing device unit, in which four developing devices 12, 14, 16 and 18 respectively having cyan, magenta, yellow and black toners are arranged symmetrically with respect to a rotation shaft 20. The developing device unit 10 is configured to be rotatable around a rotation shaft 20 and is capable of forming a toner image of any color of four colors on the photoconductor 2. A transfer drum 22 rotates in a direction of an arrow 26 while contacting the photoconductor 2 in a state where the paper 24 is wound around the transfer drum. The cyan toner image 28 formed on the photoconductor 2 is transferred onto the rotating paper 24 by the transfer device 30. The paper 24 to which all the four color toner images have been transferred is conveyed to the fixing device 30 and printing is completed. The untransferred toner 32 on the photoconductor 2 is scraped off by the cleaner 34 to complete a series of processes.

The operation of the color electrophotographic apparatus constructed as described above will be supplementarily described below.

FIG. 3 is a timing chart showing the process of forming a color image. As can be seen from this figure, the transfer of image information, the formation of a toner image on the photoconductor 2 and the transfer onto the paper 24 are carried out serially one by one in the order cyan, magenta, yellow and black.

[0008]

However, in the above-mentioned configuration, the color switching is performed by the four-color developing devices 12, 1
Since this is done by rotating 4, 16, 18 there are the following problems. That is, 1. Developing devices 12, 14, 16, 18 require large output motors for switching. 2. Developing device 12, 14, 16, 18 It is necessary to secure sufficient strength of the developing device unit 10 in order to ensure accuracy or relative positional accuracy with the photoconductor, for example, development gap, and inevitably increase in size or cost of the device. . 3. Noise or vibration is generated when switching.

The present invention solves the above problems.
A first object of the invention is to provide a color electrophotographic apparatus which has a simple structure, is inexpensive, and is free from vibration and the like. The second purpose is to reduce color shift when four colors are overlapped,
It is an object of the present invention to provide a color electrophotographic apparatus capable of producing a high-quality color image.

[0010]

In order to solve the above problems, a color electrophotographic apparatus of the present invention has at least a photoconductor, a developing device and a charging device, and uses cyan, magenta yellow and black toners, respectively. Therefore, four process means for forming an image on the photoconductor, at least one light source for exposing the photoconductor according to image information, and a toner image on each photoconductor are transferred at four different positions. Intermediate transfer means and a paper transfer means for transferring the image of the intermediate transfer means to a paper, and the process means sequentially operate one color at a time so that each toner image formed on each photoreceptor is It is configured to be superposed on the intermediate transfer means.

[0011]

[Function] At least a photoconductor, a developing device, and a charging device are provided,
At four different positions, four process means for forming an image on the photoconductor with cyan, magenta yellow, and black toners, respectively, and at least one light source for exposing the photoconductor according to image information. An intermediate transfer means for transferring the toner image on each of the photoconductors and a paper transfer means for transferring the image of the intermediate transfer means onto a paper are provided, and each of the process means is sequentially operated for each color.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color electrophotographic apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the arrangement of a color electrophotographic apparatus according to the first embodiment of the present invention. In FIG. 1, 42, 44, 46, and 48 are photoconductors having a diameter of 30 mm, 50, 52, 54, and 56 are chargers, and 58, 6
Numerals 0, 62 and 64 are developing units containing cyan, magenta, yellow and black toners, respectively. As shown in FIG. 4, the developing units 58, 60, 62, 64 have toner storage units 74, 76, 78 at the ends (front side of the apparatus main body).
Has 80. In this embodiment, each toner container 74,
Approximately 1000 printable toners are stored in 76, 78, 80, and toner bottles 82, 84, 86, 8 are stored.
The toner is replenished by means of No. 8.

In the developing units 58, 60, 62 and 64, the developing rollers 90, 92, 94 and 96 are made of an elastic material, and the photoconductor is formed through the toner formed on the developing rollers 90, 92, 94 and 96. This is a so-called non-magnetic one-component thin layer developing system in which 50, 52, 54 and 56 are pressed against each other.

The untransferred toners 98, 100, 102, 104 remaining on the photoconductors 50, 52, 54, 56 without being completely transferred, which will be described later, are the photoconductors 50, 52, 5 respectively.
4, 58, 60, 62, 6
The so-called cleaning-less system is adopted in which development is carried out and cleaning is carried out at the same time.

The above-mentioned developing method and cleaning method are known techniques and will not be further described.

LEs 106, 108, 110 and 112
D and 114 are drive circuits for driving LEDs, and 116 is a signal circuit for generating image signals. LEDs 106, 10
8, 110 and 112 are switches 122, 124 and 12
6,128 selectively activates only one.

Reference numeral 118 denotes an intermediate transfer belt to which a voltage is applied via a drive roller 130 made of a conductor. Photoconductor 4
The toner images formed on 2, 44, 46, and 48 are once transferred to the intermediate transfer belt 118, and finally transferred to the paper 24 by the transfer roller 120. A reference position marker 134 is provided on the intermediate transfer belt 118 as shown in FIG. 5, and the timing of starting writing of each toner image is determined by a signal from a detection sensor 136 fixed to the main body and facing the reference position marker 134. ing.

FIG. 6 is a timing chart showing the process of creating a color image, and the operation will be described based on this.

Next, a method for maintenance of this apparatus will be described below. Generally, the following two methods are generally adopted for the maintenance of this type of device. The first is a method of contracting with a service company and requesting the company to perform maintenance, and the second is a method of making a process section into a so-called cartridge so as to be maintenance-free.

On the other hand, the electrophotographic apparatus of this embodiment is maintenance-free, but employs a third method different from the above method. That is, the photoconductor 4 that constitutes the process
2, 44, 46, 48 or developing units 58, 60, 6
The lifespan of the main parts such as 2, 64, etc. is substantially matched with the lifespan of the main body of the device, and the parts are designed not to be replaced regularly. Of course, the parts are replaceable assuming that the parts need to be repaired irregularly (for example, the parts are accidentally damaged). The photoconductors 42, 44, 46 and 48 generally have the shortest life among the main parts, and the life is set to 50,000 sheets in this embodiment. As for the toner, the user can use the toner bottles 82 and 8 as described above.
You can replenish each time with 4, 86, 88.

Next, a description will be given in terms of maintaining high image quality.
As a problem in achieving high image quality of this type of color electrophotographic apparatus, there is a problem of color misregistration in superimposing toner images of four colors. In this embodiment, the four photoconductors 42, 4
4, 46, 48 and LEDs 106, 108, 110, 11
When the two pixel rows are not all parallel, for example, when only the photoconductor 42 is deviated from parallel as shown in FIG. 7, even if four colors are finally overlapped, only one color is deviated and high image quality cannot be realized. . In this embodiment, at least the photoconductors 42, 44, 4
6, 48 and LEDs 106, 108, 110, 112.
Since it is positioned and fixed to the main body of the apparatus, it is easy to ensure accuracy, and since these parts have the life of the main body apparatus, it is possible to stably maintain high image quality even after they are on the market. As an example of the positioning method on the apparatus main body, The parts are positioned with reference to the main body chassis (not shown). 2. At least the above parts are unitized to ensure accuracy and the unit is positioned on the main body chassis. Position adjustment means is provided in 3.1. Various configurations such as are possible.

The embodiment of the present invention has been described above. Needless to say, the color electrophotographic apparatus realizing the present invention is not limited to the above configuration.

As shown in FIG. 8, laser scanners 146, 148, 150 and 152 may be used as light sources instead of LEDs. Further, a line light source using liquid crystal or another light source may be used.

The process is not necessarily limited to the non-magnetic one-component thin layer developing and cleaning system.

Further, as shown in FIG. 9, the paper 24 may be conveyed by the transfer belt 160 and directly transferred to the paper 24 without using the intermediate transfer belt 118.

[0027]

As described above, the present invention has at least a photoconductor, a developing device, and a charging device, and four sets for forming an image on the photoconductor with cyan, magenta, yellow, and black toners, respectively. Process means and at least one light source for exposing, each process means being sequentially 1
By operating color by color and transferring to a transfer material such as an intermediate transfer belt or paper, it is possible to provide an apparatus that is inexpensive and has less vibration.

Further, let L1 be the number of printed sheets of life of the four sets of process means, L2 be the number of printable toners stored in the toner container of the developing device, and L3 be the number of printed lifespans of the image forming apparatus main body. Since L1≈L3> L2 is substantially set at the time of factory shipment

[Brief description of drawings]

FIG. 1 is a front sectional view of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a front sectional view of a conventional color electrophotographic apparatus.

FIG. 3 is a timing chart of a conventional color electrophotographic apparatus.

FIG. 4 is a partially cutaway external view of a developing device of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 5 is an external view of an intermediate transfer belt of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 6 is a timing chart of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 7 is a diagram showing a positional relationship between a photoconductor and an LED of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 8 is a diagram for explaining another embodiment of the light source.

FIG. 9 is a front sectional view of a color electrophotographic apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 42, 44, 46, 48 Photoreceptor 58, 60, 62, 64 Developing device 106, 108, 110, 112 LED 122, 124, 126, 128 Switch 118 Intermediate transfer belt

Claims (6)

[Claims] 1. A process unit comprising at least a photoconductor, a developing unit and a charging unit, which forms an image on the photoconductor with each of cyan, magenta, yellow and black toners, and image information. Accordingly, at least one light source for exposing the photoconductor, intermediate transfer means for transferring the toner image on each photoconductor at four different positions, and paper transfer for transferring the image of the intermediate transfer means onto paper A color electrophotographic apparatus, wherein each of the process means sequentially operates for each color, and the toner images formed on the photoconductors are superposed on the intermediate transfer means. 2. The life printing number of four process means is L
1. If L2 is the number of printable sheets of toner stored in the toner storage unit of the developing device and L3 is the number of printable images of the image forming apparatus main body, then L1≈L3> L2 is substantially satisfied. The color electrophotographic apparatus according to claim 1. 3. The color electrophotographic apparatus according to claim 1, wherein the light source is four linear light sources corresponding to each process means. 4. At least four photoconductors, a developing device, and a charging device, and four process means for forming an image on the photoconductor with cyan, magenta, yellow, and black toners, respectively, and image information. Each process comprises: at least one light source that exposes the photoconductor in accordance with the above; and a transfer unit that conveys the paper and transfers the toner image on each photoconductor to the paper at four different positions. The color electrophotographic apparatus is characterized in that the means operate sequentially one color at a time, and the toner images formed on the respective photoconductors are superposed on the paper on the transfer means. 5. The number of printed sheets of the life of four process means is L
1. If L2 is the number of printable sheets of toner stored in the toner storage unit of the developing device and L3 is the number of printable images of the image forming apparatus main body, then L1≈L3> L2 is substantially satisfied. The color electrophotographic apparatus according to claim 1. 6. The light source is four line-shaped light sources corresponding to each process means.
The described color electrophotographic apparatus.