JPH01307776A - Color electrophotographic device - Google Patents

Abstract

PURPOSE:To simplify the constitution of a device by commonly using the same electrostatic charging device and changing voltage of a high voltage power source which impresses a voltage on that electrostatic charging device according to the purpose. CONSTITUTION:One corona electrostatic charger 23 is used and AC voltage is set to be impressed a fixed voltage on. DC bias component which superimposes on it is controlled according to the purpose, a color toner image is formed on a photosensitive body 15 and is transferred onto a paper 21. After AC corona impressed a voltage which is superimposed on the AC voltage with DC bias component to residual toner on the photosensitive body 15 on the electrostatic charger 23 is emitted, the photosensitive body 15 is cleaned by a cleaner 24. Thus, the constitution of the device is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color electrophotographic device that can be used in a hard copy device such as a color copying machine or printer.

Conventional technology In recent years, after repeating charging φ exposure φ development multiple times to form multiple toner images of different colors on an electrophotographic photoreceptor (hereinafter referred to as photoreceptor), the toner images are transferred all at once to paper to produce color images. Color electrophotographic devices for obtaining images are being actively studied. This method differs from conventional color electrophotography methods in that it does not require a transfer drum and has the advantage that the apparatus can be miniaturized.

An example of this type of color electrophotographic apparatus is the apparatus proposed by the inventors (Japanese Patent Application No. 82-4367).

Hereinafter, an embodiment of the present invention will be described using FIG. 4.

The developing device 1.2.3 is a non-contact type non-magnetic one-component developing device that uses a DC electric field to scatter the toner, and the toner is tribo-electrified with a conductive fur brush 4.5.6 that is in contact with the developing roller. , a thin layer of toner is formed by a blade 10.11.12 on an aluminum developer roller 7.8.9. The developing device 1 contains yellow (Y) insulating toner, the developing device 2 contains magenta (M), and the developing device 3 contains cyan (C) insulating toner. The developing device 13 is a contact type developing device containing a two-component developer. and developing roller 7.8
．． The developing devices were placed opposite each other around the photoreceptor 15 with a constant gap (development gap) between the photoreceptor 15 and the photoreceptor 15. Each developing device is attached with a separation mechanism that brings it close to the photoreceptor during development and separates it when not developing.

152-m diameter photoreceptor sensitized to long wavelengths in the infrared region
Using an amorphous 5e-Te photoreceptor drum 15, the circumferential speed is 18
Rotate at 0+im/s. This photoreceptor 15 is connected to a charger 1
6 (Suflotron charger, corona voltage; +7kV,
Grid voltage: 1 kV) to a charging potential of +900 V. Next, a semiconductor laser 17 with a wavelength of 790 nm is
Emits light and exposes it. Using this semiconductor laser 17,
A negative black signal is exposed on the photoreceptor 15 to form an electrostatic latent image. The latent image is reversely developed by the black developing device 13 in a developing state in which +eoov is applied to the developing roller 14 to form a black toner image, and then the photoreceptor 15 is neutralized by the static eliminating lamp 18 .

Next, the photoreceptor 15 is charged with the corona charger 16 again for 10 eoov.
is charged with electricity. After that, the semiconductor laser 17 is placed on the photoreceptor 15.
A signal light corresponding to yellow is exposed to form a yellow electrostatic latent image. Next, this photoreceptor is placed on the developing roller 7 by +6
A yellow toner image is formed by passing through a yellow developing device 1 in a developing state to which 00■ is applied, a magenta developing device 2, a cyan developing device 3, and a black developing device 13 in a non-developing state.

Next, without removing the charge from the photoreceptor 15, the photoreceptor 15 is charged to +810 again by the corona charger 18.
Charged to V. Thereafter, a semiconductor laser 17 is used to expose a signal light corresponding to magenta to form a magenta electrostatic latent image. Next, the photoreceptor 15 is transferred to the yellow developing device 1 in a non-developing state.
, to form a magenta toner image by passing through the magenta developing device 2 in a developing state in which +800V is applied to the developing roller 8.

Thereafter, the photoreceptor 15 is passed through the cyan developer 3 and the black developer 14 in a non-developing state.

Next, the photoreceptor 15 is subjected to corona exposure using an AC corona charger 19 (applied voltage: 5 kV rms), and the photoreceptor 15 is charged to +800V again by the corona charger 16. Thereafter, a semiconductor laser 17 is used to expose the semiconductor laser 17 to signal light corresponding to cyan to form a cyan electrostatic latent image. next,
The photoreceptor 15 is passed through a yellow developer 1 in a non-developing state, a magenta developer 2 in a non-developing state, and a cyan developer 3 in a developing state in which +5oov is applied to the developing roller 9 to form a cyan toner image on the photoreceptor. Complete the image.

The color toner image thus obtained on the photoreceptor 15 is transferred onto paper 21 by a transfer charger 20, and then thermally fixed by a fixing device 22. On the other hand, after the transfer, the surface of the photoreceptor 15 is
Pre-cleaning charger 23 (corona voltage +5.5kV)
After being positively charged, the conductive fur brush 24 to which a voltage of -150V has been applied is pressed against the photoreceptor 15, and then subjected to leaning.

Problems to be Solved by the Invention In the conventional example described above, two chargers, the AC corona charger 19 and the DC corona charger 23, are used in the image forming process. Each of them is used for a different purpose, and the AC corona charger 19 is used to prevent color turbidity due to a decrease in charging potential in the red area, and the DC corona charger 2
3 is used to align the polarity of toner remaining on the photoreceptor after transfer and to assist in cleaning. When one of these two corona chargers is in use, the other is not in use. The use of these two chargers complicates the configuration, and requires two types of high-voltage power sources, one for direct current and one for alternating current, which has the drawback of increasing the cost of the device.

In view of this, the present invention shares the same charger in order to achieve a plurality of image forming purposes, and switches the voltage of the high-voltage power supply applied to the charger according to the purpose.
It is an object of the present invention to provide a color electrophotographic device whose device configuration is extremely simple.

Means for Solving the Problems The present invention provides a main charger for charging a photoreceptor, a yellow, magenta, evening, and cyan color developer, a pre-cleaner charger, and a DC bias component A and a DC bias component B that are switched between each other. A color electrophotographic apparatus comprising a power source that applies a voltage to the pre-cleaner charger superimposed on an AC voltage, and a cleaner, the apparatus comprising: a charging process, an exposure process, a developing process, and the DC bias for each image forming process; The alternating current corona radiation step in which a voltage obtained by superimposing component A on the alternating current voltage was applied to the pre-cleaner charger was repeated to form a color toner image on the photoconductor, and after transferring it to paper, the toner image remained on the photoconductor. The color electrophotographic apparatus cleans the photoreceptor using the cleaner after irradiating the toner with an AC corona in which a voltage in which the DC bias component B is superimposed on the AC voltage is applied to the cleaner pre-charger.

Action With a single corona charger, the AC voltage is set so that a constant voltage is applied, and only the DC bias component superimposed on it is used to clean the DC bias component with a small comb when the purpose is to prevent red charging potential from decreasing. The above problem can be solved by making the size larger for the purpose.

Embodiment First, a functional explanation will be given. That is, in the conventional example, the purpose of using the charger 19 is when the yellow toner and magenta toner on the photoreceptor overlap due to exposure to AC corona, that is, when the photoreceptor in the red area is recharged by the charger 16. It is used to prevent dielectric breakdown and a drop in surface potential. For this reason, it is desirable that the AC voltage applied to the charger 19 at this time has no or only a small DC bias component.

One charger 23 is a pre-cleaner charger, and this charger is used for corona exposure to align the polarity of the toner remaining on the photoreceptor after transfer in one direction. In the conventional example described above, a positive DC voltage is applied to the charger 23. Here, even if an AC voltage superimposed with a DC bias component that positively charges the photoconductor is applied to the charger 23, the polarity of the toner on the photoconductor can be made uniform, and the pre-cleaner charger It was found that this effect can be obtained. However, it has been found that even if this AC voltage with a DC bias component superimposed is applied as it is to the charger 23 and used for the purpose of preventing the charging potential of the red portion of the charger 19 from decreasing, it is hardly effective. Ta.

Therefore, the power source applied to the corona charger used in the present invention is preferably within the range described below. Here, DC bias component A means a voltage used for the purpose of preventing dielectric breakdown during recharging of the red part, and DC bias component B means a voltage used for pre-cleaner charging. Note that the specific circuit configuration of such an AC power source is well known in the art and will not be described here.

- Range of AC voltage; 3, 5 to 8 kVrms Range of DC bias component A to be 1 volt: 0 to +400V Range of superimposed DC bias component B: +400 to +1200V In the present invention, for the purpose of preventing a drop in the charging potential of the red part A slight alternating current corona discharge causes a direct current bias component A to be applied to the photoreceptor at least after the magenta developing process and before the cyan charging process.
It is effective to expose the AC corona using a charger that applies an AC/AC voltage with a superimposed voltage, but the same effect can be obtained even if the exposure is continued during all image formation processes for black, yellow, magenta, and cyan. There is. This effect of corona exposure was particularly effective when the photoreceptor was an amorphous selenium-based photoreceptor. It was also effective when the photoreceptor was an amorphous selenium arsenic photoreceptor. It goes without saying that in the case of, for example, an organic photoconductor having a negative charging polarity, the polarity of the superimposed DC bias component will be negative.

Hereinafter, embodiments of this improved invention will be described again with reference to the drawings.

In this device, the charger 19 is removed from the device described in the conventional example, and the power source connected to the charger 23 is replaced from the DC high voltage power source to the AC high voltage power source in which the DC bias component described above can be switched.

The developing device 1.2.3 is a non-contact type non-magnetic one-component developing device that uses a direct current electric field to scatter the toner, and the toner is charged by friction with a conductive fur brush 4.5.6 that is in contact with the developing roller. A thin layer of toner is formed by a blade 10.11.12 on the aluminum developing roller 7.8, θ. Developing device 1 has yellow (Y), developing device 2
contains magenta (M) insulating toner, and the developing device 3 contains cyan (C) insulating toner. The developing device 13 is a contact type developing device containing a two-component developer consisting of an insulating toner and a magnetic carrier, which is widely used in electrophotographic devices. Each developing device was disposed around the photoreceptor 15 so as to face each other with a constant gap (development gap) between the developing roller 7, 8, 9, 14 and the photoreceptor 15.

Each developing device is equipped with a separation mechanism that brings it close to the photoreceptor 15 during development and away from it when not developing.

The specifications and development conditions of the black developer 13 and the physical properties of the toner are shown below.

・Developer specifications and developing conditions Diameter of developing roller 14: 22 mm Peripheral speed of developing roller 14: 320+am/s Developing roller 1
Thickness of developer layer on 4: 400 μm・Rotation direction of developing roller 14: Opposite direction to photoreceptor 15 (same traveling direction) Development gap (gap between developing roller surface and photoreceptor surface): 300 μm during development 1 Non-development Time 2 [Developer physical properties Type of developer: Two-component developer: toner and carrier Average particle size of carrier: Approximately 50 μm Carrier plate: Teflon coated ferrite Toner charge m: +10 ALc/g Toner average particle size: 8 μm
m Toner relative dielectric constant: Approximately 2 The specifications and development conditions of the yellow, magenta, and cyan developers and the physical properties of the toner are shown below.

・Developer specifications and developing conditions Diameter of developing roller = 20 Dragon Peripheral speed of developing roller: 180+i/S Direction of rotation of developing roller: Opposite direction (same traveling direction) as photoreceptor 15 Toner layer on developing roller Thickness: 30μm development gap (
Gap between the developing roller surface and the photoconductor surface): 150 μm during development 1 2+n when not developing [Toner physical properties Cotoner charge amount: +3 μC/g Average particle size: 10 μm Relative dielectric constant: Approx. 2 Long in the infrared region as a photoconductor Wavelength sensitized diameter 152.8
．． Amorphous 5e-Te photoreceptor drum 15 (photosensitive layer thickness 83μm1, dielectric constant approximately 7, functionally separated selenium photoreceptor sensitized to long wavelengths in the infrared region, half-decreased exposure at wavelength 790nI11, 0.6μJ/c+e) peripheral speed of 160/
Rotated with s. This photoreceptor 15 was charged to a charging potential of +900 V using a charger 18 (Scorotron! Denki, corona voltage: +7 kV1, grid voltage: 1 kV).

Next, the semiconductor laser 17 with a wavelength of 790 nm was emitted to perform exposure.

At this time, the light intensity on the photoreceptor surface was 1.2 mW. Using this semiconductor laser 17, a negative black signal was exposed onto the photoreceptor 15 to form an electrostatic latent image. The latent image is reversely developed by the black developer 13 in the developing state with +800V applied to the developing roller 14 to form a black toner image, and then the AC corona charger 23 (AC voltage: 5 kvrms, DC bias component A: +200V) ) After exposing the photoreceptor 15 to AC corona, the static electricity was removed from the photoreceptor 15 using the electricity removal lamp 18.

At this time, the thickness of the black toner layer developed on the photoreceptor 15 is 1
The thickness of the toner layer is 10 to 2 layers. 201
．． It was tm.

Next, the photoreceptor 15 was again charged to +eoov using the corona charger 16 (Scorotron charger, corona voltage: +7 kVs, grid voltage 2,600 cm).

At this time, the charged potential of the photoreceptor 15 to which the black toner was attached was 600V. Thereafter, the photoreceptor 15 was exposed to signal light corresponding to yellow by the semiconductor laser 17 to form a yellow electrostatic latent image. Here, the exposure amount of the semiconductor laser was set to 1.2 mW on the photoreceptor surface. Next, this photoreceptor is passed through a yellow developer 1 in a developing state with +600V applied to the developing roller 7, a magenta developer 2, a cyan developer 3, and a black developer 13 in a non-developing state to form a yellow toner image. was formed. After that, AC corona charger 23 (AC voltage; 5 kVrms, DC bias component A; +
After exposing the AC corona at 200V), the corona charger 16 (scorotron band [1,:Irona voltage: +7
The photoreceptor 15 was charged to +850V by kV% (grid voltage: 900V). At this time, the charged potential of the photoreceptor 15 to which the black and yellow toners are attached is 870V.
Became. Thereafter, a semiconductor laser 17 was used to expose signal light corresponding to magenta to form a magenta electrostatic latent image.

A yellow developing device 1 has the photoreceptor 15 in a non-developing state, and a magenta developing device 2 has a developing state in which +830V is applied to the developing roller 8.
to form a magenta toner image. At this time, the toner layer in the overlapping portion of yellow and magenta on the photoreceptor 15 has 2 to 4 layers, and its thickness is 20 to 40 μm.
It was m.

Thereafter, the photoreceptor 15 was passed through a cyan developer 3 and a black developer 13 in a non-developing state. Next, the photoreceptor IS is charged again with the AC corona charger 23 (AC voltage: 5kVrms,
Then, the photoreceptor 15 was charged again to +850 V by the corona charger 16. At this time, the charged potential of the photoreceptor 40 to which only black, yellow, and magenta toners were attached became +870V. Further, the charged potential of the photoreceptor 15 in the area where the yellow and magenta toners overlapped became +800■. Thereafter, a semiconductor laser 17 was used to expose a signal light corresponding to cyan to form a cyan electrostatic latent image.

The photoreceptor 15 is passed through a yellow developer 1 in a non-developing state, a magenta developer 2, and a cyan developer 3 in a developing state with +830V applied to the developing roller 9 to form a cyan toner image on the photoreceptor. Completed color image.

The color toner image thus obtained on the photoreceptor 15 was transferred onto paper 21 by a transfer charger 20, and then thermally fixed by a fixing device 22. On the other hand, after the transfer, the surface of the photoreceptor 15 is
AC corona charger 23 (AC voltage; 5kVrms,
After the surface potential of the photoreceptor was charged to +300V using DC bias component B (+800 .mu.), the conductive fur brush 24 to which a voltage of -350V was applied was brought into pressure contact with the photoreceptor 15 for cleaning.

As a result, the color density of the composite color of the red, green, and blue solid areas is 1.
5 or higher, and a clear color image with high color purity was obtained without cyan toner being mixed into the red area. Additionally, the toner remaining on the photoreceptor could be completely cleaned. This image forming process was repeated for 1000 sheets in a row, but no cyan fogging occurred in the red portion, and no background staining due to poor or poor cleaning occurred.

Effects of the Invention As described above, according to the present invention, the same charger is shared in order to achieve a plurality of image forming purposes, and the voltage of the high-voltage power supply applied to the charger is switched depending on the purpose. As a result, it is possible to obtain a color electrophotographic apparatus with an extremely simple apparatus configuration.

[Brief explanation of the drawing]

The figure is a configuration diagram of a color electrophotographic apparatus according to an embodiment of the present invention. 1.2.3...Developer, 13...Developer (black), 1
5... Photoreceptor, 16... Corona charger, 17...
Semiconductor laser, 23... AC corona charger.

Claims (1)

[Claims] Main charger that charges the photoreceptor, yellow, magenta, and cyan color developers, pre-cleaner charger, DC bias component A
A color electrophotographic apparatus comprising a cleaner and a power source for applying a voltage to the pre-cleaner charger by switching between and a DC bias component B and superimposing it on an AC voltage, the apparatus comprising: a charging step; A color toner image was formed on the photoreceptor and transferred to paper by repeating an exposure step, a development step, and an AC corona radiation step in which a voltage obtained by superimposing the DC bias component A on the AC voltage was applied to the cleaner pre-charger. After that, after irradiating the toner remaining on the photoconductor with an AC corona in which a voltage obtained by superimposing the DC bias component B on the AC voltage is applied to the pre-cleaner charger, the photoconductor is cleaned using the cleaner. color electrophotographic equipment.