JPH08278674A - Color image forming device - Google Patents

Abstract

PURPOSE: To bring the application of an electrostatic charging voltage to each electrostatic charging means for color into a non-operating state in the case of forming a black image by using a simple mechanism and controlling the mechanism. CONSTITUTION: By joining a lead wire I for connecting each electrostatic charging electrode of electrostatic chargers 11(Y), 11(M) and 11(C) in parallel, a lead wire II for connecting the electrode of an electrostatic charger 11(K) and a lead wire III for connecting the grid of each electrostatic charger 11 in parallel to a socket S on a device body side through a plug P on a cartridge 3 side, they are connected to a constant current power supply and a constant voltage power supply. In the case of forming the color image, a switch SW on the constant current power supply side is turned on so as to impress the electrostatic charging voltage on all the electrodes, meanwhile, in the case of forming a monochromatic image, the switch SW is turned off, simultaneously, a current value to be outputted us reduced to 1/4 and the electrostatic charging voltage is impressed on only the electrode of the electrostatic charger 11 (K).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a plurality of charging means, image exposing means and developing means arranged on the peripheral surface of an image forming body.
The present invention relates to an electrophotographic color image forming apparatus that forms a color image by superimposing toner images during one rotation of an image forming body.

[0002]

2. Description of the Related Art As an apparatus for recording a multicolor image, the same number of charging means, image exposing means and developing means as the types of colors required for image formation are arranged around the image forming body.
A color image in which charging, image exposure, and development for each color are sequentially performed while the image forming body makes one round, and the toner images are superposed to form a color toner image, which are collectively transferred onto a transfer material. Forming devices are known.

In such an apparatus, since the formation of the toner image of each color is continuously started with a slight time difference, the speed of color image formation is high, and a color image larger than the length of the peripheral surface of the image forming body is formed. It also has the feature that it can be formed.

[0004]

As described above, such an apparatus is of a type in which each charging means and each developing means simultaneously start their operations simultaneously with the start of copying because each toner image is continuously formed. Therefore, even the charging unit and the developing unit, which are not necessary even when forming a so-called monochrome image of only the specified color, are placed in an operating state.

As a result, a plurality of charging means always perform a discharging action to generate a large amount of ozone, which accelerates deterioration of the photosensitive member,
Further, there is a problem that the toner is deteriorated and color mixture occurs due to the idle operation of the developing unit, and the life of the mechanical section is shortened.

To solve this problem, it is desirable to control the operation of each charging means and each developing means individually in accordance with the respective toner image forming processes, but the circuits and mechanisms are complicated and the cost is high. As it rises, it becomes a difficulty in realizing it.

According to the present invention, since a black and white image is the main component of a monochrome image, a color image forming apparatus capable of solving the above-mentioned problems with an extremely simple circuit structure and operating mechanism without increasing the cost. It is intended to be provided.

[0008]

The above-mentioned object is to provide a charging means, an image exposing means, and a developing means for the toner images of a plurality of color colors and black on the peripheral surface of the image forming body. A color image forming apparatus for transferring the toner images collectively onto a transfer material after the toner images of the respective colors are overlapped and formed by repeating charging, image exposure and development during one rotation of the image forming body. Is capable of forming a black image, and each charging unit uses one constant current power source as a charging power source and directly connects a charging unit corresponding to a black toner image to the power source, and each charging unit corresponds to each color. 1 charging means
This is achieved by a color image forming apparatus characterized by being connected in parallel via individual switches.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

Reference numeral 10 denotes a drum-shaped image forming body, that is, a photosensitive drum, in which an organic photosensitive layer (OPC) composed of a transparent conductive layer is applied to the outer periphery of a substrate formed of a transparent member such as optical glass or transparent acrylic resin. Then, it is rotated clockwise while being grounded.

In this embodiment, in the photoconductor layer of the photoconductor drum, which is the image formation point of the exposure beam for image exposure, an appropriate contrast is obtained with respect to the light attenuation characteristics (photocarrier generation) of the photoconductor layer. It suffices that the exposure light amount has a wavelength that can be applied. Therefore, the light transmissivity of the transparent substrate of the photosensitive drum in the present embodiment does not have to be 100%, and may have a characteristic that some light is absorbed when the exposure beam is transmitted. As the material of the light-transmitting substrate, various light-transmitting resins such as soda glass, Pyrex glass, borosilicate glass and fluorine, polyester, polycarbonate, polyethylene terephthalate used for general optical members can be used. Further, as the translucent conductive layer, indium tin oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, Au, Ag, N
A metal thin film made of i, Al or the like and maintaining a light-transmitting property is used.
Various sputtering methods, various CVD methods, dip coating methods, spray coating methods and the like are used. As the photoconductor layer, an amorphous silicon (a-Si) alloy photosensitive layer,
Amorphous selenium alloy photosensitive layer and various organic photosensitive layers (O
PC) can be used.

Reference numeral 11 denotes a scorotron charger, which is a charging means, which performs a charging operation on the above-mentioned organic photoreceptor layer of the photoreceptor drum 10 by a grid held at a predetermined potential and a corona discharge by a discharge wire. A uniform electric potential is applied to the drum 10.

Reference numeral 12 denotes an exposure optical system which is an image exposure means, and includes LEDs, FL, EL and P arranged in the axial direction of the photosensitive drum 10.
It is composed of a light emitting element such as L and a SELFOC lens as a unity magnification imaging element. The image signals of the respective colors read by the separate image reading device are sequentially taken out from the memory and input to the exposure optical systems 12 as electric signals. The emission wavelengths of the light emitting devices used in this example have the same wavelength, and are in the range of 500 to 900 nm.

Each of the exposure optical systems 12 is attached to a common columnar support member 20, and each exposure optical system 12
(Y), 12 (M), 12 (C) and 12 (K) are arranged at equal intervals and are housed inside the base body of the photosensitive drum 10. The exposure optical system 12 includes a lamp, an LCD, and an L in addition to the above light emitting element.
It may be composed of a combination of optical shutter members such as ISA and PLZT and an imaging lens such as a SELFOC lens.

13Y, 13M, 13C and 13K are yellow (Y), magenta (M), cyan (C) and black (K).
The developing device, which is a developing means for accommodating each developer, includes a developing sleeve 130 that rotates in the same direction with a predetermined gap from the peripheral surface of the photosensitive drum 10.

Each of the developing devices 13 does not contact the electrostatic latent image on the photosensitive drum 10 formed by the charging by the charging device 11 and the image exposure by the exposure optical system 12 by applying a developing bias voltage. Reverse development in the state.

Next, the process of the color image forming apparatus in this apparatus will be described.

The original image is temporarily read as an image signal for each color of Y, M, C and K from an image read by an image pickup device or an image edited by a computer in an image reading apparatus separate from this apparatus. Stored and stored in memory.

When the image recording is started, the photoconductor drive motor is rotated to rotate the photoconductor drum 10 in the clockwise direction, and at the same time, the charging action of the charger 11 (Y) starts to apply the potential to the photoconductor drum 10. To be done.

After the photosensitive drum 10 is applied with an electric potential,
In the exposure optical system 12 (Y), image exposure is started by an electric signal corresponding to the first color signal, that is, an image signal of yellow (Y), and the yellow of the original image ( An electrostatic latent image corresponding to the image of Y) is formed.

The latent image is reverse-developed by the developing device 13 (Y) with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further given a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second color signal of the exposure optical system 12 (M), that is, Image exposure is performed by an electric signal corresponding to the magenta (M) image signal, and non-contact reversal development by the developing device 13 (M) causes the magenta (M) toner on the yellow (Y) toner image. The images are sequentially superimposed and formed.

By the same process, a cyan (C) toner image corresponding to the third color signal is finally generated by the charging device 11 (C), the exposure optical system 12 (C) and the developing device 13 (C), and finally. Black (K) corresponding to the fourth color signal by the charger 11 (K), the exposure optical system 12 (K) and the developing device 13 (K)
Toner images are sequentially superposed and formed on the photosensitive drum.
A color toner image is formed on the peripheral surface within one rotation of 10.

The color toner image thus formed on the peripheral surface of the photosensitive drum 10 is a transfer material which is conveyed from the paper feed cassette 15 in the transfer device 14A and is fed in synchronization with the driving of the timing roller 16. It is transferred onto the transfer paper.

The transfer paper on which the toner image has been transferred is a static eliminator.
In 14B, the charge is removed and the toner is separated from the peripheral surface of the drum. After the toner is fused and fixed in the fixing device 17, the toner is discharged through the paper discharge roller 18 onto the tray above the device.

On the other hand, the photosensitive drum 10 from which the transfer paper has been separated removes and cleans the residual toner in the cleaning device 19 and continues to form a toner image of the original image, or temporarily stops the toner of the new original image. Wait for image formation.

The photoconductor drum 10 is composed of the chargers 1
1, an exposure optical system 12, a developing device 13, a cleaning device 19, and toner container 40 for supplying toner to each of the developing devices 13 and the cleaning device 1.
The toner is stored in the color process cartridge 30 together with the waste toner container 50 that stores the toner collected in step 9, and is attached and detached by sliding in parallel from the right side with the side cover 80 of the apparatus main body opened.

FIG. 2A is an explanatory view showing a wiring circuit for each of the above chargers 11. Each charger 11 has a charging voltage from the power source of the main body of the apparatus through three wiring circuits.
Electric current is supplied.

Charger 11 (Y), 11 (M), 11
Each electrode of (C) is in parallel with the lead wire I and the charger 11 (K)
Is connected in parallel to the lead wire II, and the grid of each charger 11 is connected in parallel to the lead wire III to be connected to the plug P on the back surface of the cartridge 30.

The respective lead wires I, II and III are connected to the socket S of the main body by automatically connecting the plug P to the main body of the apparatus by mounting the cartridge 30 in the direction of the arrow of the cartridge 30. It is designed to be connected to the power supply section on the side.

The lead wire I can be connected to the lead wire II via a switch SW provided on the power source side, or the switch S as shown in FIG. 2B.
W is provided on the cartridge 30 side so that it can be connected to the lead wire II on the cartridge 30 side.

FIG. 3 shows a circuit diagram of connection of each power source to each charger 11. In the power source section, constant current control is automatically performed in response to environment, electrode contamination, etc., and set current value is switched. And a constant voltage power source that constantly outputs a constant voltage to each grid of the charger 11.

When the color mode is selected as the copy mode, the switch SW is set to ON, and each charger 11 supplies the electrodes with a predetermined current value required for charging the photoconductor from the constant current power source. For example, a current I ₀ flows, and at the same time, a predetermined voltage is applied to the grid by the constant voltage power source to perform the above-described color image formation.

On the other hand, when the monochrome mode is selected as the copy mode, the set current value of the constant current power source is switched to 1/4 of that in the previous color mode, and at the same time, the switch SW is set to OFF. Charger 11
(K) a predetermined current value only to the electrodes I _0/4 is swept away by the charger 11 (Y), 11 (M) , 11 (C) is a non-operating state, the exposure optical system 12 (Y), 12 (M), 12
(C) and developing devices 13 (Y), 13 (M), 13
The respective operations of (C) are also suspended, and monochrome image formation is performed.

Therefore, each charger 11 is used efficiently only when it is necessary according to the selection of the copy mode, and it can be used for a long time, the amount of harmful ozone is small, and the electric power is effective. It will be consumed.

In this embodiment, the exposure optical system 12 is described as an apparatus arranged inside the photoconductor drum 10.
The present invention uses a laser unit 12 used as an image exposure means.
0 (YM) and 120 (CK) can be applied to an apparatus in which the photosensitive drum 10 is arranged outside or on the outside of the process cartridge 30 as shown in FIG. 4. In this case, the process cartridge 30 is an apparatus. The plug P is attached and detached by sliding in the depth direction from the front side of the plug P to join and unjoin the plug P to the socket S.

[0037]

According to the present invention, a plurality of charging means can be efficiently operated in accordance with a color or monochrome image forming mode with an extremely simple mechanism and its operation control, and as a result, harmful ozone is less generated. Therefore, it is possible to provide a color image forming apparatus capable of obtaining a high-quality color image for a long period of time by preventing deterioration of the photoconductor.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus of the present invention.

FIG. 2 is an explanatory view showing a wiring route for each charging unit.

FIG. 3 is a circuit diagram of a charging voltage.

FIG. 4 is a configuration diagram of a main part of another color image forming apparatus.

[Explanation of symbols]

 10 Photoreceptor Drum 11 (Y) Charger (Yellow) 11 (M) Charger (Magenta) 11 (C) Charger (Cyan) 11 (K) Charger (Black) 12 Exposure Optical System 13 Developer 14A Transferr 15 Paper Feed Cassette 17 Fixing Device 19 Cleaning Device 20 Supporting Member 30 Process Cartridge P Plug S Socket SW Switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Hama ▼ Tauta Takata 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Stock Company

Claims (3)

[Claims] 1. A charging unit, an image exposing unit and a developing unit corresponding to a plurality of color and black toner images are provided on the peripheral surface of the image forming body, and the image forming body is rotated once. In a color image forming apparatus that repeatedly forms a toner image of each color by repeating charging, image exposure, and development, and then transfers the toner images to a transfer material collectively, the apparatus enables formation of a black image. Each charging unit uses one constant current power source as a charging power source, and directly connects the charging unit corresponding to the black toner image to the power source, and one charging unit corresponding to each color is connected to one switch. A color image forming apparatus characterized in that the color image forming apparatuses are connected in parallel via the same. 2. The charging power source changes a current value according to switching of an image forming mode.
The described color image forming apparatus. 3. The color image forming apparatus according to claim 1, wherein the grid of the charging unit is controlled by a constant voltage.