JPH03202872A - Color image forming method - Google Patents

Abstract

PURPOSE:To stabilize the transfer of toner and obtain a color image of high quality by performing corona discharging simultaneously with signal exposure and setting an electrostatic discharging potential above 0V and below the initial corona potential of a photosensitive body. CONSTITUTION:Simultaneously with signal exposure to the photosensitive body 15, a corona discharger 22 performs corona discharging to set the discharging potential of the photosensitive body 15 below the initial corona charging potential and above 0V. At this time, a corona charger 20 which has a grid electrode 32 is used as the electrostatic discharger 22 and a bias voltage is applied to the electrode 32 at the same time with the signal exposure to control the electrostatic discharging potential of the photosensitive body 15. Then even if the potential of a toner layer to be developed varies owing to variation in the toner layer thickness or an environmental change, the photosensitive body can be adjusted to a desired electrostatic discharging potential. Consequently, the transfer of toner, which is already developed, to image receiving paper is stabilized and the color image of high quality is obtained.

Description

[Detailed Description of the Invention] The present invention relates to a color image forming method that can be used in a hard copy device such as a copying machine or a printer. Various color electrophotographic methods have been proposed in which a plurality of toner images of different colors are formed in advance on an electrophotographic photoreceptor (hereinafter referred to as photoreceptor) several times and the toner images are transferred all at once to paper to obtain a color image. An apparatus to which this type of color electrophotographic method is applied will be explained with reference to FIG.

Developer 1. 2. 3 is a non-contact type non-magnetic one-command developing device that uses a DC electric field to fly the toner, and 4. is a conductive fur brush that is in contact with the developing roller. 5. 6, the toner is triboelectrically charged, and an aluminum developing roller 7, 8. Blade 10 on top of 9. 11. Even if the configuration is such that a thin layer of toner is formed using
, magenta (M) in developer 2, and cyan (M) in developer 3.
Even if the insulating toner of C) is contained, the developing device 13 is a black developer containing two-common developer consisting of an insulating toner and a magnetic carrier, which is widely used in electrophotographic devices.
k) Contact type developer and developing roller 7.8
The developing devices are disposed around the photoreceptor 15 so as to face each other with a constant gap (developing gap) between the photoreceptor 15 and the photoreceptor 15. Even though each developing unit is equipped with a separation mechanism 16, 17, 18, 19 that moves close to the photoreceptor during development and away from it during non-development, the photoreceptor 15 is charged to a charging potential by a charger 20 (corotron charger corona voltage knee 7 kV). Charging to -1800V At this time, the lamp 21 is placed on top of the charger at the same time as charging.
Next, the surface of the photoreceptor is neutralized using a corona static eliminator 22 (corona applied voltage 2 AC 4.5 kVrms, 1 kHz, grid voltage 2 0 V). When a negative black signal is exposed and the entire surface of the intuitive light body 15 is irradiated with light from the lamp 24, a potential of 0 V appears in the laser signal exposed area and -830 V in the signal non-exposed area.This latent image is transferred to the developing roller. Black (B) in the developed state with -aoov applied to 14
A black toner image was formed by reversal development using the developing device 13 (lack), and then static electricity was removed using the corona static eliminator 25 (corona applied voltage 2 AC, 4.5 kVrmS, 1 kH2). The photoreceptor 15 is charged to -1800V using the corona charger 20 (corotron charger, corona voltage = 7kV).At this time, the charged potential of the photoreceptor 15 in the area where the black toner is attached is -2400V.
Furthermore, corona static eliminator 22 (corona applied voltage 2 AC 4.5 kVrms, 1 kHz, grid voltage:
The semiconductor laser 23 is made to emit light while eliminating static electricity on the surface using the Ov), and a negative yellow signal is exposed onto the photoreceptor 15.Then, the entire surface of the photoreceptor 15 is irradiated with light from the lamp 24.
Then, Ov is applied to the laser signal exposed part of the bare part and the toner-attached part, -830V is applied to the laser signal non-exposed part of the bare part,
A potential of -930 V appears in the part where the toner is attached and which is not exposed to the laser signal.
The yellow toner image is formed by passing it through a yellow developer L in a developed state to which 0V is applied, and a magenta developer 2, a cyan developer 3, and a black developer 13 in a non-developing state. (Corona applied voltage 2 AC 4
, 5kVrma, 1kHz), and then, while irradiating light with the lamp 21 again, the corona charger 20 (corotron charger, corona voltage = 7kV) "i'liJ light body 1
5 is charged to -1800V, but at this time, the charged potential of the photoconductor 15 in the areas where the black and yellow toners are attached is -12V.
At 40 QV, the surface is neutralized using a corona static eliminator 22 (corona applied voltage: AC 4, 5 kVrma, 1 kHz, grid voltage: Ov), and the semiconductor laser 23 is made to emit light, producing a negative magenta signal on the photoreceptor 15. After that, the entire surface of the photoreceptor 15 is irradiated with light from the lamp 24. Then, the laser signal exposed part of the bare part and the toner-attached part is Ov, the laser signal-unexposed part of the bare part is -830V, and the toner-attached part is 1830V. Although a potential of 1,030 V appears in the non-exposed portion of the laser signal, the photoreceptor 15 is then passed through a yellow developer l in a non-developing state and a magenta developer 2 in a developing state in which a voltage of 1,800 V is applied to the developing roller 8. After forming a magenta toner image, the photoconductor 15 is passed through the cyan developer 3 and black developer 13 in a non-developing state.
rms, 1kHz).

Finally, while irradiating light with the lamp 21 again, the g-light body 15 is charged to -1800V with the corona charger 20 (using a corotron band, corona voltage: +7kV).
The charged potential of the photoreceptor 15 in the area where the yellow and magenta toners are attached is -2400V.Next, the corona static eliminator 2
2 (Corona applied voltage: AC (?iE4.5kVrma
, 1kHz, grid voltage: 0V), the semiconductor laser 23 is made to emit light, and a negative cyan signal is exposed on the photoreceptor 15.Then, the entire surface of the photoreceptor 15 is irradiated with light from the lamp 24. A potential of 0 V appears in the bare area and the laser signal exposed area of the toner-adhered area, 1830 V in the bare area unexposed to the laser signal, and 1930 V in the laser signal unexposed area of the toner-adhered area. 15 is passed through a yellow developing device L in a non-developing state, a magenta developing device 2, and a cyan developing device 3 in a developing state in which a voltage of -800 V is applied to the developing roller 9, a cyan toner image is formed into a cyan toner image in the form 1.
1i1 A color image is completed on the photoreceptor 15.

The color toner image thus obtained on the photoconductor 15 is transferred onto the paper 29 which has been brought into close contact with the transfer belt 28 using the paper adsorption brush 26 and the paper adsorption charger 27 using the transfer charger 30, and then is transferred to the paper 29 by the transfer charger 30, and is then transferred to the paper 29 by the fixing device 31 to make it glossy. Author Sumo -X
Transfer machine The surface of the photoreceptor 15 is removed by a corona static eliminator 25 (
Corona applied voltage: AC 4. 5kVrma 1kHz
The conductive fur brush 32 was negatively charged with a DC voltage of -800V and then a voltage of 150V was applied.
Problems to be Solved by the Invention In this conventional electrophotographic method, the photoreceptor with toner adhered to it is partially neutralized by the corona static eliminator 22 during signal exposure. At the same time, the static electricity is removed from the toner that has adhered to the surface.The electrostatic transfer force of the previously developed black, yellow, and magenta toner onto the image receiving paper. GEL G In a color image forming method in which color toner is superimposed on a light body to obtain a full color image, it is used to stabilize the transfer of the previously developed toner to the image receiving paper.
An object of the present invention is to provide a color image forming method that allows high-quality color images to be obtained.

Means for Solving the Problems Present Invention 41 A photoreceptor having a transparent insulating layer on the surface of the photosensitive layer is used.1. Using black, yellow, magenta, and cyan toners, corona charging, corona static elimination at the same time as signal exposure, and repeating the cycle of full-surface light irradiation and development with the toner several times to overlay a color toner image on the photoreceptor. A color image forming method for directly obtaining a color image by overlaying, characterized in that the static elimination potential of the photoreceptor by corona static elimination simultaneously with the signal exposure is lower than the initial corona charging potential of the photoreceptor and higher than 0V. In a color image forming method, the toner is not completely neutralized during corona static elimination at the same time as the action signal exposure, but some of the charge remains to the extent that it does not affect image formation. It can also be transcribed by
At this time, if a grid is attached to the corona static eliminator and the potential of the toner is controlled by the grid, the amount of developed toner adhered to the photoreceptor changes and the potential of the toner can always be kept constant. More effective example for stabilizing transfer Photoreceptor 15+1 used in the present invention has a structure in which a 25 μm thick transparent polyester resin layer (surface insulating layer) is coated on the surface of a 50 μm thick selenium photosensitive layer. Here, the lower photosensitive layer (with 25% tellurium added and a thickness of approximately 0.1
It is composed of two layers: a μm-thick selenium tellurium alloy layer (charge generation layer) and a pure selenium layer (charge transfer layer) made of pure selenium.

In addition to this selenium, the photosensitive layer used in the present invention can be a general electrophotographic photoreceptor such as a cadmium sulfide organic photoreceptor. , lower than the initial corona charging potential of the photoreceptor;
However, when the initial corona charging potential is 1800V, it is better to set the neutralization potential in the range of 0 to -1800V.Furthermore, stable toner transfer characteristics and good In order to achieve both image formation, a range of 0 to -300V is desirable. At this time,
When trying to adjust the static elimination potential to a more desirable one, the potential tends to fluctuate when the thickness of the toner layer to be transferred or developed changes or the environment changes. By applying a bias voltage to this grid electrode using a charger (scorotron), it becomes possible to more stably control the static elimination potential of the photoreceptor.

A word that leaves an amount of charge on the toner to stabilize the transfer characteristics. It is not necessary for all cycles of black, yellow, magenta, and cyan (1, i.e. plate). At least for the last color to be formed, it is necessary to Static neutralization potential of the photoconductor due to simultaneous corona static neutralization It is acceptable if the potential is lower than the initial corona charging potential of the photoconductor and higher than 0V.Instead, for colors other than the last to be imaged, set the neutralization potential to 0V.
It is better to lower the grid voltage to 100% for color overlapping development.In this way, switch the grid voltage only when forming the final image.
It is desirable to increase the static elimination potential.Firstly, a specific embodiment of the present invention will be described in detail with reference to FIG. 2. 3 is a non-contact type non-magnetic l-component developer that uses a DC electric field to fly the toner, and 4. is a conductive fur brush that is in contact with the developing roller. 5. 6, the toner is triboelectrically charged, and an aluminum developing roller 7, 8. Blade 10 on top of 9. 11. Even if the configuration is such that a thin layer of toner is formed by
), the developing device 2 contains magenta (M) insulating toner, and the developing device 3 contains cyan (C) insulating toner. Developing device 131-1
This is also a contact type developer containing a two-component developer consisting of an insulating toner and a magnetic carrier, which is widely used in electrophotographic devices.The developing roller 7, 8. 9. 14 and the photoreceptor 15 (developing gap) is kept constant, and each developer is installed opposite to the photoreceptor 15 around the photoreceptor 15. Each developer is close to the photoreceptor during development and is separated from the photoreceptor when not developing. ．． 17. 18. The specifications and development conditions of the developing device 13, which is black even when the developer 19 is attached, and the physical properties of the toner are shown below.

[Developer specifications and developing conditions: diameter of developing roller 14: 22 mm circumferential speed of developing roller 14: 340 mm/s developing roller 14
Thickness of the developer layer on the surface: 400 μm Direction of rotation of the developing roller 14: 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): 400 μm during development to 400 μm during non-development 2mm [Developer physical properties] Type of developer: Average particle size of secondary developer of toner and carrier: Approximately 50 μm Type of carrier: Silicone resin coated ferrite toner Charge amount: -10 μC/g Average particle size of toner: 8 μm Toner relative dielectric constant: Approximately 2 The specifications and development conditions of yellow, magenta, and cyan developers and the physical properties of the toner are shown below.

[Developer specifications and development conditions] Diameter of the developing roller: 20 mm Peripheral speed of the developing roller: 160 mm/s Rotation direction of the developing roller: Opposite direction (same traveling direction) as the photoreceptor 44 Thickness of toner layer on the developing roller: 32 μm Development roller rotation direction: Photoconductor 15 and opposite direction Development gap (gap between development roller surface and photoconductor surface): During development 15
0 μm and 2 mm when not developed [Physical properties of toner] Toner charge amount 2 -3 μC/g Average particle size: 10 μm Relative dielectric constant: Approximately 2゛The photoreceptor 15 is charged with a charger 20 (corotron charger corona voltage: -7 kV) At this time, at the same time as charging, a lamp 21 is used to irradiate light from above the charger, and a corona static eliminator 22 having a grid 32 (corona applied voltage: AC 4.5
While the surface of the photoreceptor was being neutralized at kVrms, 1kHz, grid voltage: Ov), the semiconductor laser 23 was made to emit light.
A negative black signal is exposed onto the photoreceptor 15. After that, the entire surface of the photoreceptor 15 is irradiated with light from the lamp 24.1. Then,
A potential of 150V appeared in the laser signal exposed area and 1830V potential appeared in the signal non-exposed area.This latent image was reversely developed by the black developing device 13 in the developing state with 1600V applied to the developing roller 14, and a black toner was developed. Makoto in the form of a statue Corona static eliminator 25
(Corona applied voltage 2 AC 4.5kVrms, lk, H
z), and then the photoreceptor 15 was charged to -1800V with the corona charger 20 (corotron charger, corona voltage knee 7kV) while irradiating light with the lamp 21.At this time, the photoreceptor 15 was charged to -1800V with the corona charger 20 (corotron charger, corona voltage knee 7kV). The charged potential of the body 15 is -240
When the voltage reached 0V, the semiconductor laser 23 was further removed while removing static electricity from the surface using the corona static eliminator 22 (corona applied voltage - AC 4.5kvrms, 1kHz, grid voltage: 0V).
The mold photoreceptor 15 was irradiated with light from the lamp 24 over the entire surface of the mold photoreceptor 15. Then, the laser signal of the bare area and the toner-attached area was 0V at the exposed area, and the exposed area was 0V. -830V for the laser signal non-exposed area
, 1030V for the laser signal non-exposed area of the toner adhesion area
Then, this photoreceptor is passed through a yellow developer 30 in a developing state where -800V is applied to the developing roller 7, and a magenta developer 2, a cyan developer 3, and a black developer 13 in a non-developing state. Corona static eliminator 25 (corona applied voltage:
AC 4. After removing static electricity at 5kVr+r, 1kHz)
The photoreceptor 15 was charged to -1800V with the corona charger 49 (corotron charger, corona voltage near kV) while being irradiated with light from the lamp 21 again. At this time, the charged potential of the photoreceptor 15 in the areas where the black and yellow toners were attached was as follows. -2400
After reaching V, the corona static eliminator 22 (corona applied voltage:
Semiconductor laser 23 while removing static electricity from the surface with AC 4, 5kVrms, 1kHz, grid voltage: 0V>
After that, the entire surface of the photoreceptor 15 is irradiated with light from the lamp 24. Then, the laser signal of the bare area and the toner-attached area is 0V at the exposed area, and the exposed area of the bare area is 0V. 18 for the laser signal non-exposed area
30V, 19V for the laser signal non-exposed area of the toner adhesion area.
When a potential of 30 V appears, the photoreceptor 15 is then passed through a yellow developer 1 in a non-developing state and a magenta developer 2 in a developing state in which a voltage of 1,800 V is applied to the developing roller 8 to form a magenta toner image. A resistive corona static eliminator 25 (corona applied voltage: AC 4.5 kVrma,
At the end, the light body 15 was charged to -1800V using the corona charger 20 (Corotron charger, corona voltage: +7kV) while irradiating light with the lamp 21.
The charged potential of the photoreceptor 15 in the area where the yellow and magenta toners were attached became -2400 V. Next, the corona static eliminator 22 (corona applied voltage 2 AC 4.5 kVrma, 1
kHz, grid voltage: -100V) to eliminate static electricity on the surface.The semiconductor laser 23 is made to emit light, and a negative cyan signal is exposed on the photoreceptor 15.
When the entire surface is irradiated with light from the lamp 24, 150 V is applied to the exposed parts of the bare part and the toner-adhered part, 1880 V is applied to the part of the bare part that is not exposed to the laser signal, and 1880 V is applied to the part of the bare part that is not exposed to the laser signal. A potential of -980v appeared.
Next, the photoreceptor 15 is passed through a yellow developing device 1 in a non-developing state, a magenta developing device 2, and a cyan developing device 3 in a developing state in which 185 QV is applied to the developing roller 9 to form a cyan toner image and then exposed to light. The color toner image thus obtained on the photoreceptor 15 is transferred onto a paper 29 that has been brought into close contact with a transfer belt 28 using a paper suction brush 26 and a paper suction charger 27, and then is transferred by a transfer charger 30 to a paper 29 that has been brought into close contact with a transfer belt 28. The transferred truth is thermally fixed by the fixing device 31? ,,−
X Transfer machine The surface of the photoreceptor 15 is
(Corona applied voltage: AC 4.5kVrmS, 1kH
conductive fur brush 3 to which a voltage of 150 V was applied.
2 was pressed against the photoreceptor 15 and cleaned.As a result, transfer defects occurred even when printing under conditions of relative humidity of 80%.Effects of the invention that always produced beautiful color images. In a color image forming method in which color toners are superimposed to form a full color image, it is possible to obtain a color image forming method that stabilizes the transfer of the previously developed toner to the image receiving paper and obtains a high quality color image.

[Brief explanation of drawings]

FIG. 1 shows one of the apparatuses using the color image forming method of the present invention.
It is a sectional view of an example. 1...Yellow developed image 2...Magenta developed image 3.
... Cyan developer 13... Black developer 15... Photoreceptor 20... Corona charging @ 21... Lamp,
22...Corona static elimination W 23...Semiconductor Lasermi 24...Lamp, 32...Glyph

Claims (3)

[Claims] (1) Using a photoreceptor having a transparent insulating layer on the surface of the photosensitive layer, using black, yellow, magenta, and cyan toners, a cycle of corona charging signal exposure, simultaneous corona charge removal, whole surface light irradiation, and development with the toner. A color image forming method in which a color toner image is directly superimposed on the photoconductor to obtain a color image by repeating the process multiple times, the charge removal potential of the photoconductor due to the corona charge removal simultaneously with the signal exposure being A color image forming method characterized in that the potential is lower than the initial corona charging potential of and higher than 0V. (2) A method for performing corona charge removal simultaneously with signal exposure using a corona charger having a grid electrode, characterized in that the charge removal potential of the photoreceptor is controlled by applying a bias voltage to the grid electrode. Claim 1
Color image forming method described in Section 1. (3) In the process of at least the final image forming color among black, yellow, magenta, and cyan, the charge removal potential of the photoreceptor due to corona charge removal at the same time as the signal exposure is lower than the initial corona charging potential of the photoreceptor. 2. The color image forming method according to claim 1, wherein the potential is higher than 0V.