JPH01307775A - Color electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent other color toner mixing into a black developing unit when a device is reset by performing black image forming process at the outset of an image forming process and making a black developing unit approach to a photosensitive body at the last order of each developing unit in the reset process of the device. CONSTITUTION:Black is developed in condition where developer is made contact with the photosensitive body and yellow, magenta and cyan are developed in condition where developer is not made contact with the photosensitive body. Black image forming process is performed at the outset of the image forming process and the black developing unit 13 is made to approach to the photosensitive body at the last order of each color developing units 1-3 in the reset process of the device. While that, during the photosensitive body rotates, a cleaning device 24 removes toner on the photosensitive body. Thus, color toner is prevented from mixing into the black developing unit which is made to approach lastly to the photosensitive body.

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, charging and exposure development are repeated multiple times to form multiple toner images of different colors on an electrophotographic photoreceptor (hereinafter referred to as photoreceptor), and then 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 an apparatus proposed by the inventors (Japanese Patent Application No. 82-4387).

Embodiments of the present invention will be described below with reference to the drawings.

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.The toner is tribo-electrified by a conductive fur brush 4.6.6 that is in contact with the developing roller. A thin layer of toner is formed by a blade 10.11.12 on a developer roller 7.8.9 made of a similar material. Developing device 1 contains yellow (Y) insulating toner, developing device 2 contains magenta (M), and 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, θ,
Each developer is disposed around the photoreceptor 15 so as to face each other with a constant gap (developing gap) between the photoreceptor 14 and the photoreceptor 15. Each developing device is close to the photoconductor during development, and is separated from the photoreceptor when not developing.
A detachment mechanism is installed.

Photoreceptor with a diameter of 152 mm and sensitized to long wavelengths in the infrared region.
Using an amorphous 5e-Te photoreceptor drum 15 of
! Rotate at 0+u/s. This photoreceptor 15 is connected to a charger 1
6 (Scorotron charger, corona voltage: +7 kV
Charge potential +900 due to N grid voltage: 1kV)
Charge it to V. Next, the semiconductor laser 17 having a wavelength of 790 nm is caused to emit light for exposure. Using this semiconductor laser 17, a negative black signal is exposed onto 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 with +θ00V 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 to +600V using the corona charger 16 again.
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.
A yellow toner image is formed by passing through a yellow developing device 1 in a developing state to which oov has been applied, and a magenta developing device 2, a cyan developing device 3, and a black developing device 13 in a non-developing state.

Then, without removing the charge from the photoreceptor 15, the photoreceptor 15 is charged to +810V again by the corona charger 16.
It was charged with electricity. 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 developer 1 in a non-developing state.
A magenta toner image is formed by passing through the magenta developing device 2 in a developing state in which +5 oov 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 +800V is applied to the developing roller 9 to form a cyan toner image on the photoreceptor. Complete the color image on top.

After the color toner image thus obtained on the photoreceptor 15 is transferred to the paper 2'1 by the transfer charger 20, the fixing device 22
It is heat-fixed by On the other hand, after the transfer, the surface of the photoreceptor 15 is charged to the pre-cleaning charger 23 (corona voltage +5.5 kV).
), and then the conductive fur brush 24 to which a voltage of -150V is applied is brought into pressure contact with the photoreceptor 15 for cleaning.

In this way, in this conventional example, black development is performed first.

Problems to be Solved by the Invention In this method, the order in which images are formed on the photoreceptor is black, yellow, magenta, and cyan. Here, the developing device for black is a developing method in which the photoreceptor and the developer are in contact with each other, and the other developing methods for yellow, magenta, and cyan are the direct current electric field splash development method in which the photoreceptor and the developer are not in contact with each other. In the conventional example, 1. Heat development, which is a contact development method, is performed first, and then yellow and yellow are developed.
By repeating the image forming process in the order of magenta and cyan to create a color image, color turbidity in the developing device is prevented. However, when resetting the device due to a paper jam, etc., when the developing devices are pressed against the photoconductor in the order of black, yellow, magenta, and cyan in the same way as during image formation, other color toners get mixed into the black developing device. However, it was found that significant color turbidity occurred. .

In view of this, an object of the present invention is to prevent toners of other colors from getting mixed into the black developing device when the device is reset due to a failure such as a paper jam.

Means to Solve the Problem 6 The method of solving the problem is to repeat the charging, exposing, and developing steps for each color image forming process of black, yellow, magenta, and cyan, and after forming a color image on the photoconductor, transfer it to paper. A color electrophotographic apparatus for transferring, wherein each of the black, yellow, magenta, and cyan developing devices has a mechanism that approaches the photoconductor during development and separates from the photoconductor at other times, and A color electrophotographic apparatus, wherein the developing method is a developing method in which a developer comes into contact with the photoconductor, and each of the yellow, magenta, and cyan developing methods is a developing method in which the photoconductor and the developer are in non-contact, In the image forming step, a black image forming step is performed first, and in the apparatus reset step, the black developing devices are brought close to the photoreceptor in the order of the last of the developing devices.

In an electrophotographic device that transfers color toner images all at once to a device formed on a photoconductor as described in the conventional example, when the image forming process is stopped due to an obstacle such as a paper jam, all the color toner images are transferred onto the photoconductor. toner remains attached. If you enter the reset operation and first bring the black developer close to the photoconductor, the color toner on the photoconductor will mix into the black developer because the black developer develops by contacting the photoconductor. Resulting in. However, according to the present invention, the color developing device is first brought close to the photoreceptor. At this time, the color developing device uses a DC electric field flying development method in which the developer and the photoreceptor are not in contact with each other.
Even if toner remains on the photoreceptor, toner will not get mixed into the color developing device. During this time, while the photoreceptor continues to rotate, the toner on the photoreceptor is removed by the cleaning device, so it is possible to prevent color toner from getting mixed into the black developing device, which is finally brought close to the photoreceptor.

Example Embodiments of the present invention will be described below with reference to the drawings.

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. The blades 10.11, 12 form a thin layer of toner on the aluminum developing roller 7.8, θ. Developing device 1 has yellow (Y), developing device 2
contains insulating toner of magenta (M), and insulating toner of cyan (CC') is contained in the developing device 3. 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 attached 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 development conditions Diameter of developing roller 14: 22. .

Peripheral speed of developing roller 14: 320 mm/S developing roller 1
Thickness of the developer layer on 4: 400 μm Rotating direction of the developing roller 14 2° Opposite direction to the photoreceptor 15 (same traveling direction) Development gap (gap between the surface of the developing roller and the surface of the photoreceptor): 300 μm during development 1 Non-development Type of developer: Two-component developer: toner and carrier Average particle size of carrier: Approx. 50 μm Type of carrier: Teflon coated ferrite Toner Charge amount: +10 μC/g Average particle size of toner: 8 μl Toner Specification of yellow, magenta, and cyan developing devices, development conditions, and physical properties of toner are shown below.

・Developer specifications and development conditions Development roller diameter: 20 Dragon Peripheral speed of development roller: 160-■/S Development roller rotation direction: Opposite direction to photoreceptor 15 (same traveling direction) Toner layer on development roller Thickness: 30 μm Development gap (gap between the surface of the developing roller and the surface of the photoreceptor): 150 μm during development 1 2 times during non-development [Physical properties of toner Toner charge amount: +3 μC/g Average particle size: 10 μm Relative permittivity: Approx. 2 Binder resin: Styrene/acrylic resin Amorphous 5e-Te photoreceptor drum 15 with a diameter of 152.8 ms (photosensitive layer thickness: 63 μm) sensitized to long wavelengths in the infrared region as a styrene/acrylic resin photoreceptor
1 Specific dielectric constant 7, functionally separated selenium photoreceptor with long wavelength sensitization in the infrared region, wavelength 790n! Half exposure ff1 at I+
o, 6μJ/crs2) and a circumferential speed of 160! l■/S
I rotated it. This photoreceptor 15 was charged to a charging potential of +900 V using a charger 16 (Scorotron w electric device, 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 is 1.2 m
It was W. Using this semiconductor laser 17, the photoreceptor 1
5 was exposed to a negative black signal to form an electrostatic latent image. The latent image is reversely developed by the black developing device 13 in a developing state in which +5 oov is applied to the developing roller 14 to form a black toner image, and then an AC corona charger 23 (AC voltage; 5 kVrm) is applied to the latent image.
s1 DC bias component; +200 V) to expose the photoreceptor 15 to an AC corona, and then the photoreceptor 15 was neutralized using a static elimination lamp 18.

At this time, the thickness of the black toner layer developed on the photoreceptor 15 is 1
There are two layers, and the thickness of the toner layer is 10 to 20 μm.
Met.

Again, the photoreceptor 15 was charged to +eoov using the corona charger 16 (Scorotron charger, corona voltage: +7 kV1, grid voltage: 600 V). At this time, the charged potential of the photoreceptor 15 to which the black toner was attached was 600V. Thereafter, the photoreceptor 15 is illuminated with yellow by the semiconductor laser 17. A yellow electrostatic latent image was formed by exposure to signal light.

Here, the exposure amount of the semiconductor laser was set to 1.2 on the photoreceptor surface.
It was set to mW.

Next, this photoreceptor is passed through a yellow developing device 1 in a developing state in which +eoov is applied to the developing roller rough, a magenta developing device 2 in a non-developing state, a cyan developing device 3, and a black developing device 13 to form a yellow toner image. Formed. Next, after detonating the AC corona with the AC corona charger 23 (AC voltage: 5 kVrmss, DC bias component; +200 V), the corona charger 16 (Scorotron charger, corona voltage: +7 kV, grid voltage: 90
0V), the photoreceptor 15 was charged to +850V. At this time, the charged potential of the photoreceptor 15 to which the black and yellow toners were attached became 870V.

Thereafter, a semiconductor laser 17 was used to expose signal light corresponding to magenta to form a magenta electrostatic latent image. next,
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 +830■ 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 mm.
It was μm. Thereafter, the photoreceptor 15 was passed through a cyan developer 3 and a black developer 13 in a non-developing state. Next, the photoreceptor 15 is charged again with the AC corona charger 23 (AC voltage: 5
k Vrms, DC bias component; +200V)
The photoreceptor 15 was charged to +850V again by the corona charger 16. At this time, the charged potential of the photoreceptor 40 to which only black, yellow, and magentan toners were attached was 870V. Further, the charged potential of the photoreceptor 15 at the portion where the yellow and magenta toners overlapped became 800V.

Thereafter, a semiconductor laser 17 was used to expose a 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, 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 above.

When the color toner image thus obtained on the photoreceptor 15 was transferred to the paper 21 by the transfer charger 20, a paper jam occurred. A toner image in which four types of toner were superimposed remained on the photoreceptor.

After removing the paper 21 from inside the device, the device was reset. First, the photoreceptor 15 was rotated, and then the far plan cleaner 24 was pressed against the photoreceptor 15.

After that, each rotation of the photoreceptor 15 causes yellow, magenta,
Each of the cyan developing devices was pressed against the photoreceptor 15 in turn, and finally the black developing device 13 was brought into pressure contact with the photoreceptor 15. The toner image remaining on the photoreceptor 15 was removed by the cleaner 24 before the black developer 13 was brought into pressure contact with the photoreceptor 15, so the toner image remained on the photoreceptor 15 in the black developer 13. No toner was mixed in.

Effects of the Invention According to the present invention, it is possible to prevent toners of other colors from getting mixed into the black developing device during a reset operation of the photoreceptor due to occurrence of a problem such as a paper jam.

[Brief explanation of the drawing]

The figure is a schematic 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, 24...far plan cleaner.

Claims (1)

[Claims] In a color electrophotographic device that repeats the charging, exposing, and developing steps for each color image formation process of black, yellow, magenta, and cyan to form a color image on a photoreceptor, it is then transferred to paper. - Each developing device for magenta and cyan has a mechanism that approaches the photoreceptor during development and separates from the photoreceptor at other times, and develops black while the developer is in contact with the photoreceptor. , and the yellow, magenta, and cyan development is performed without contact between the photoreceptor and the developer, and in the image forming step, the black image forming step is performed first, and in the device reset step, the black developing device is The color electrophotographic apparatus is characterized in that the developing units are located close to the photoreceptor in the last order of the developing units.