JPH03229279A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To obtain images which are all uniform by providing a control means which starts copying operation by driving a copying process system when the arrival of a specific latent image formation surface at a copying operation start position is detected from the use order of the latent image formation surface and the output of a latent image formation surface detecting means. CONSTITUTION:A CPU 23 controls the copying process system 25 consisting of respective means for the copying operation according to the detection signals of transmission type optical sensors 21 and 22, a control program stored in a memory 24 as a storage means, and a copy mode set on a console panel 26. When the arrival of the latent image formation surface in current use order is detected, the copying process system 25 is driven to start the copying operation to equalize the use frequencies of respective latent image formation surfaces 3a and 3b of a photosensitive body 3. Consequently, the uniform images can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to an electrophotographic apparatus such as a full-color copying machine equipped with a photoreceptor belt on which a plurality of latent image forming surfaces are set.

[Conventional technology]

In a conventional full-color copying machine as an electrophotographic apparatus, for example, two latent image forming surfaces 51a and 51b are set on the photoreceptor belt 51, as shown in a standby state P1 in FIG. Electrostatic latent images are formed on these latent image forming surfaces 51a and 51b by an exposure operation using reflected light from a document guided by an optical system (not shown), and these electrostatic latent images are formed in each color of yellow, magenta, and cyan. The toner images are developed by the developing devices 52a to 52c individually containing toners, and the toner images of each color thus formed are transferred onto the same portion of a transfer intermediate (not shown) in an overlapping manner, and this toner image is further transferred to paper. By doing so, a copy image can be obtained on paper.

In such a full-color copying machine, when making a full-color copy of A4 size, for example, the photoreceptor belt 5
1, the latent image forming surface 51a is used twice for yellow and cyan exposure and development (P2 and P4);
1b is used once for magenta exposure and development (P3).

In addition, when making multiple full-color copies of A4 size, the photoreceptor heald 51 is attached to the latent image forming surface 51a on the odd-numbered copy.
is exposed to yellow and cyan and developed twice at CP2.
- P4), the latent image forming surface 51b is used once for magenta exposure and development (P3), and the latent image forming surface 51b is used once for magenta exposure and development (P3), and the latent image forming surface 51b is
The latent image forming surface 1a is used once for magenta exposure and development (P6), and the latent image forming surface 51b is used twice for yellow and cyan exposure and development (P5 and P7). The use of the latent image forming surfaces 51a and 51b in other copying modes is set as shown in Table 1 below.

[Problem to be solved by the invention]

However, in the conventional full-color copying machine described above, when making one full-color copy of A4 size, the number of times the latent image forming surface 51a and the latent image forming surface 51b of the photoreceptor heald 51 are used is different. When a large number of copies are made under such conditions, there will be a large difference in the frequency of use of the latent image forming surfaces 51a and 51b. If you make multiple full-color copies of A4 size in this situation, the density and color tone will be different between the even-numbered and odd-numbered copies, making it impossible to obtain uniform images. There is a problem with this. The above phenomenon occurs because deposits are formed on the latent image forming surfaces 51a and 51b of the photoreceptor heald 51, and the amount of deposits differs between the latent image forming surfaces 51a and 51b, which have different usage frequencies. It is considered that

[Means for Solving the Problems] In order to solve the above problems, the electrophotographic apparatus of the present invention has a plurality of latent image forming surfaces set on a photoreceptor, and uses these plural latent image forming surfaces. In an electrophotographic apparatus in which a copying operation is performed by a copying process system, the following measures are taken.

That is, there is a storage means for storing the use order of the latent image forming surfaces according to each copying mode so that the frequency of use of each latent image forming surface on the photoreceptor is equal, and a storage means for storing the use order of the latent image forming surfaces in accordance with each copying mode, and a storing means for storing the use order of the latent image forming surfaces in accordance with each copying mode such that the frequency of use of each latent image forming surface on the photoreceptor is equal, and A latent image forming surface detection means for detecting the arrival of the image forming surface, the selected copy mode, the order of use of the latent image forming surface according to the copy mode stored in the storage means, and the latent image forming surface detecting means. The apparatus includes a control means for driving the copying process system to start the copying operation when it is detected from the output that a predetermined latent image forming surface has reached a position where the copying operation can be started.

[Function] According to the above configuration, the control means controls the selected copy mode, the order of use of the latent image forming surfaces according to the copy mode stored in the storage means, and the output of the latent image forming surface detection means. When it is detected that the predetermined latent image forming surface, that is, the latent image forming surface corresponding to the order of use at that time, has arrived at the position where the copying operation can be started, the copying process system is driven to start the copying operation. Such a control operation makes it possible to equalize the frequency of use of each latent image forming surface on the photoreceptor, regardless of the copy mode.

[Example] An example of the present invention will be described below based on FIGS. 1 to 4.

An electrostatic transfer type full-color copying machine (hereinafter referred to as a copying machine), which is an electrophotographic device, has an original 11
The original document mounting table 1 made of, for example, a transparent glass plate is provided on the upper surface for placing a document. An exposure optical system 2 is disposed below the document table 1 for exposing the photoreceptor heald 3 to form an electrostatic latent image corresponding to the image of the document 11 on the photoreceptor heald 3. This exposure optical system 2 includes an exposure lamp 2 that irradiates light onto an original 11 placed on an original placing table 1.
a, a plurality of reflecting mirrors 2b that guide the reflected light from the original 11 onto the photoreceptor belt 3, an imaging lens 2C disposed on the optical path, and color filters of the three primary colors of red, green, and blue. A color separation filter 2d is provided.

The photoreceptor belt 3 has an endless sheet shape, and the 10th
It is adapted to be rotationally driven by the -ra 12a and the 20th -ra 12b. Three developing devices 4a to 4c are arranged near the center above the photoreceptor belt 3 in a non-contact state with the photoreceptor belt 3. These developing devices 4
a to 4C contain toners for each color component of yellow, macenta, or cyan, which are complementary colors of each color filter in the color separation filter 2d, and are electrostatic latent images formed on the photoconductor heald 3 by the exposure optical system 2; It is designed to supply toner to the A cleaning device 13 for removing toner remaining on the surface of the photoconductor heald 3 is provided below the photoconductor heald 3 on the 10th line 12a side. A device such as a charger 7 for charging the surface of the photoreceptor heald 3 is provided around the photoreceptor belt 3 .

In addition, three rollers 14a, 14b, 1
A sheet-like transfer intermediate 5 which is rotationally driven at 4c is in pressure contact. A transfer charger 8a that sequentially transfers the toner image formed on the photoreceptor heald 3 to the transfer intermediate 5 is disposed on the back side of the transfer intermediate 5 in a portion that is in pressure contact with the photoreceptor heald 3. Furthermore, below the transfer intermediate body 5, a transfer charger 8b that transfers the image transferred to the transfer intermediate body 5 onto the paper 15, and a separation charger 9 that separates the paper sheet 15 from the transfer intermediate body 5 are arranged.

On the other hand, paper feed cassettes 6a and 6b that accommodate paper 15 of each size are arranged below the 10th line 12a,
Half-moon rollers 20 are disposed at the locations of the paper feed cassettes 6a and 6b for appropriately feeding out the sheets 15 of the paper feed cassettes 6a and 6b. Further, downstream of the separation charger 9 in the flow of the paper 15, a conveyance belt 16 for conveying the paper 15 is provided, and downstream of this conveyance heald 16, fixing rollers 10a and 10a are provided. A fixing device 10 is provided to fix the transferred image.

In this embodiment, the photoreceptor belt 3 is set to have a length equivalent to two A3 size sheets, and a slit (not shown) is formed at the seam to form the photoreceptor heald 3 into an endless belt shape. Detection of this slit is performed by a transmission type optical sensor 21, which will be described later, and is output as a photoreceptor index. Further, the transfer intermediate 5 is A3
The length is set to the length of one size sheet, and a slit (not shown) is formed at one location for detecting a reference position. Detection of this slit is performed by a transmission type optical sensor 22, which will be described later, and is output as a transfer intermediate index. Control based on the photoreceptor index and the transfer intermediate index allows the toner images of each color component to be superimposed without misalignment.

Further, the photoreceptor belt 3 has two latent image forming surfaces 3.
a and 3b are set. In this copying machine, the order of use of the latent image forming surfaces 3a and 3b for each copying mode is set as shown in Table 1. In addition, in the same table,
a indicates the use of the latent image forming surface 3a, and b indicates the use of the latent image forming surface 3b.
furthermore, (S) indicates the use of a single copy, i.e. 1
Copying each sheet, (M) is multi-copying, that is, continuous copying of multiple sheets, monochrome is copying with one color, bicolor is copying with two colors, F
, C, respectively indicate full-color copies.

(The following is a blank space) The detection signals of the transmission type optical sensors 21 and 22 shown in the table above are inputted to the interrupt terminal of the CPU 23 shown in FIG. 3. The CPU 23 operates as shown in FIG. 1, which will be described later, based on the detection signals of the transmissive optical sensors 21 and 22, the control program stored in the memory 24 as a storage means, and the copy mode set by the operation panel 26. ,
Copying process system 2 consisting of various means for performing copying operations
It is designed to control 5. And the above CPU
23 constitutes a control means, and the transmission type optical sensor 21.
22 and the CPU 23 constitute a latent image forming surface detection means.

The memory 24 mentioned above stores an index state which is a variable and a belt start side which is also a variable. The above-mentioned variable index state changes depending on the outputs of the transmission type optical sensors 21 and 22. That is, when the joint of the photoreceptor heald 3 and the reference position of the transfer intermediate 5 are aligned, the transmission type optical sensor 21.
The output of 22 is as shown in FIG. Note that the output timing of both sensors 21 and 22 differs depending on the mounting position. When the CPU 23 detects the output of the transmissive optical sensor 21, that is, the photoconductor index, the CPU 23 resets the variable index state (0)L, and sets the transmissive optical sensor 2
2, that is, 1 is added each time the transfer intermediate index is detected. As a result, the variable index state changes to 0.12.0.1.2, etc., and by looking at this variable index state, it is determined that the transfer intermediate 5 is in the latent state of the photoreceptor belt 3 at that time. Image forming surfaces 3a and 3b
It is possible to determine which of these corresponds.

The above variable belt start side is “’0” or “
1", and when it is "0", it corresponds to the latent image forming surface 3a of the photoreceptor belt 3, and when it is "1", it corresponds to the latent image forming surface 3b. Note that this relationship may be set in the opposite direction.Also, the variable belt start side is a non-volatile memory area in the memory 24,
For example, RAM or EEPROM with bank amplifier power supply
etc. are stored.

In addition, in this copying machine, the transfer intermediate 5 is used during full-color copying.
Since the toner images of three colors are superimposed on each other, the timing of starting exposure, etc. is controlled by detecting the transfer intermediate index of the transfer intermediate 5.

In the above configuration, the operation of this copying machine will be explained below.

When the print switch is turned on, the original 11 on the original table 1 is irradiated with light from the exposure lamp 2a and scanned several times. The reflected light from the manuscript 11 is reflected by the reflection bell 2b...
The light enters the color separation filter 2d through the imaging lens 2c, and the optical image is separated into color components. On the other hand, the photoreceptor belt 3 has a 10th line 12a and a 20th line 12b.
While being driven and moved by the charger 7, it is uniformly charged by the charger 7. The optical images for each color component that have passed through each color filter of the color separation filter 2d through the multiple scans described above are sequentially image-exposed onto the photoreceptor belt 3, and the electrostatic latent An image is formed.

The electrostatic latent images for each color component that are sequentially created in this manner are developed and visualized using yellow, magenta, and cyan developers in the developing devices 4a to 4C, respectively.

The images visualized on the photoreceptor belt 3 as described above are sequentially transferred to the same position on the transfer intermediate 5 by the transfer charger 8a, and toner images for each color component are superimposed on the transfer intermediate 5. As a result, one completed color toner image is created.

Next, the above color toner image is transferred by the transfer charger 8b to the paper 15 taken out from either the paper feed cassette 6a or 6b. Thereafter, the paper 15 is separated from the transfer intermediate 5 by the separation charger 9, and introduced into the fixing device 10 via the conveyor belt 16, where the color image fixed on the paper 15 is fixed.

Next, the latent image forming surface 3 of the photoreceptor belt 3 by the CPU 23
The setting operations for a and 3b will be explained.

This control is related to the control in which the latent image forming surfaces 3a and 3b shown above are used alternately from the monochrome single copy mode using A3 paper shown in Table 1.

After the specified copy mode is entered using the copy mode setting key on the operation panel (SL), the print switch is turned on.
Then (S2), as a copy start process, the photoreceptor belt 3 and the transfer intermediate 5 are rotated, and the static elimination lamp is turned on to remove the static electricity from the photoreceptor heald 3. Furthermore, the photoreceptor heald 3 and the transfer Cleaning with the intermediate body 5 is performed (S3) Next, the joint of the photoconductor belt 3 and the reference position of the transfer intermediate body 5 are determined by the photoconductor index of the photoconductor heald 3 and the transfer intermediate index of the transfer intermediate body 5. The rotation of the transfer intermediate 5 is controlled so that they match, and when they match (S4), it is determined whether the variable index state and the variable belt start side match (S4).
5).

In S5, if the variable index state and the variable belt start side match, 1 is added to the variable belt start side (S6), the value is ANDed with "1", and it is assigned to the variable belt start side (S6). S
7). Due to the operations in steps 85 to 7, the value of the variable HertStartSide changes to “
It changes from “0” to “1” or from “1” to O”.

Next, when the transcription intermediate index is detected (S8),
A copying operation is started (S9). Thereafter, when a predetermined number of copies have been completed (SIO), the process moves to St, and if not, the process moves to S5 and the following operations are repeated.

As shown in FIG. 1(b) and FIG. 1(C), the detection of the photoconductor index and the detection of the transfer intermediate index are performed as an interrupt operation in the CPU 23, and when the photoconductor index is detected, the As shown in FIG. 4, the index state is reset (0) (S21), and then other processes such as position detection and position correction are performed (322). On the other hand, when the transfer intermediate index is detected, the index state is incremented by 1 (S31), and then other processing is similarly performed (332).

Also, among the copy modes shown in Table 1, from the monochrome multi copy mode that uses A3 paper to the lower copy modes, the above-mentioned control is not performed due to the copy speed, and other special control tables are used. , control for using the latent image forming surfaces 3a and 3b is performed in the order shown in the table. However, when changing the latent image forming surfaces 3a and 3b used,
A value corresponding to a latent image forming surface other than the latent image forming surface that was used before the change is substituted into the variable HELT START SIDE.

〔Effect of the invention〕

As described above, the electrophotographic apparatus of the present invention includes a storage means for storing the use order of the latent image forming surfaces according to each copying mode so that the frequency of use of each latent image forming surface on the photoreceptor is equal; latent image forming surface detection means for detecting arrival of each latent image forming surface to a position where copying operation can be started; a selected copying mode;
From the use order of the latent image forming surface according to the copying mode stored in the storage means and the output of the latent image forming surface detecting means,
This configuration includes a control means for driving a copying process system to start a copying operation when it is detected that a predetermined latent image forming surface has reached a position where a copying operation can be started.

Therefore, the frequency of use of each latent image forming surface of the photoreceptor can be made equal regardless of the copy mode such as single copy, multi-copy, monochrome or full color. As a result, in the multi-copy mode, for example, the situation in which the density or color differs between odd-numbered sheets and even-numbered sheets is eliminated, and a uniform image can be obtained.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention. FIG. 1(a) is a flowchart showing the control operation by the CPU shown in FIG. FIG. 4B is a flowchart showing an interrupt operation when the photoreceptor index is detected in the CPU. FIG. 4(C) is a flowchart showing an interrupt operation when a transfer intermediate index is detected in the CPU. FIG. 2 is an overall configuration diagram of a full-color copying machine. FIG. 3 is a block diagram showing the control system of the Fuller copying machine. FIG. 4 is an explanatory diagram showing the relationship between the transfer intermediate index, the photoreceptor index, and the index state. FIG. 5 shows a conventional example, and is an explanatory diagram showing the order in which latent image forming surfaces are used during single copying and multi-copying. 3 is a photoreceptor held, 3a and 3b are latent image forming surfaces, 5 is a transfer intermediate, 21 and 22 are transmission type optical sensors (latent image forming surface detecting means), and 23 is a CPU (control means, latent image forming surface detecting means). 24 is a memory (storage means), 25 is a copy process system, and 26 is an operation panel. Figure (a) Figure (b) Jar diagram (C)

Claims (1)

[Scope of Claims] 1. In an electrophotographic apparatus in which a plurality of latent image forming surfaces are set on a photoreceptor and a copying operation is performed by a copying process system using these plural latent image forming surfaces, storage means for storing the order of use of the latent image forming surfaces according to each copying mode so that the frequency of use of each latent image forming surface on the body is equal; a latent image forming surface detecting means for detecting the latent image forming surface, and a copying operation based on the selected copying mode, the use order of the latent image forming surface according to the copying mode stored in the storage means, and the output of the latent image forming surface detecting means. An electrophotographic apparatus comprising: control means for driving a copying process system to start a copying operation when it is detected that a predetermined latent image forming surface has reached a startable position.