JPH0990747A - Image forming device - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide an image forming apparatus capable of obtaining a high-quality image without causing unevenness of a printed image due to environmental changes such as temperature and humidity. [Structure] A cylindrical thinning roller 29 for controlling the layer thickness of the toner 9 carried on the developing roller 10 is provided, and the thinning roller 29 is arranged in parallel with the developing roller 10, The humidity sensor 31 detects the environment of the apparatus, and the rotation speed of the layer-thinning roller 29 is changed according to the change of the environment to change the relative peripheral speed with respect to the developing roller 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which visualizes an electrostatic latent image formed on a photoreceptor with toner particles.

[0002]

2. Description of the Related Art Conventionally, an apparatus using a dry toner has been used as an image forming apparatus and has been put to practical use as many copying machines, laser printers, plain paper facsimiles, etc., and has made remarkable progress. This image forming device is a device to which electrophotographic process technology is applied.After the electrostatic latent image formed on the photoconductor is visualized by toner particles, it is transferred to recording paper, and printing is completed after the fixing process. To do.

The structure and operation of an image forming apparatus using a non-magnetic one-component developing system will be described below with reference to the drawings.

FIG. 2 is a block diagram of a conventional image forming apparatus. A metal drum such as aluminum is used as a base material, and selenium (Se) or an organic photoconductor (hereinafter referred to as O) is formed on the outer peripheral surface thereof.
A charger 2 disposed in the vicinity of the photoreceptor 1 which is an electrostatic latent image carrier having a photosensitive receiving layer such as a PC) applied in a thin film form is made of metal and a charging wire 2a such as a tungsten wire. It is composed of a shield plate 2b and a grid plate 2c. The charging line 2a causes corona discharge to uniformly charge the photoconductor 1 through the grid plate 2c. The exposure light beam 4 emitted from the exposure optical system 3 is obtained by subjecting an image signal to light intensity modulation or pulse width modulation by a laser drive circuit (not shown),
An electrostatic latent image is formed on the photoconductor 1.

Next, the developing device 5 will be described. The toner supply roller 6 which is a toner supply member is rotatably supported at both ends by a toner hopper 7 and is agitated by a toner agitation member 8 which is bent and formed into a rectangular shape. The toner supply bias power source 11 is connected to the surface of the toner through a protective resistor 12 at the metal shaft portion.

The layer-thinning roller 29 is fixed by a layer-thinning roller holding member 30. The thinning roller 29 presses the developing roller 10 to form a layer of toner 9 on the surface of the developing roller 10.

The toner stirring member 8 draws a circular locus along with the rotation of the toner supply roller 6, and is stirred to prevent the toner 9 contained in the toner hopper 7 from aggregating. Transport to. The toner 9 supplied from the toner supply roller 6 has its toner layer thickness regulated by the thinning roller 29 and is triboelectrically charged to form a thin layer state on the outer peripheral surface of the developing roller 10. After that, the developing roller 10 is brought into contact with or in the proximity of the photoconductor 1, and the bias voltage applied from the developing bias power source 14 causes the toner 9 to be transferred and adhered to the portion of the photoconductor 1 where the electrostatic latent image is formed. Visualize the electric latent image.

The recording papers 17 stored in the recording paper cassette 16 are sent from the recording paper cassette 16 one by one to a conveying roller 19 by a half-moon shaped paper feed roller 18. The recording paper 17 sent out is conveyed in the direction indicated by the arrow A by the conveying roller 19. Registration roller 20
Is provided for temporarily stopping and waiting the recording paper 17 so that the recording paper 17 and the toner image formed on the photoconductor 1 are matched with each other. The transfer device 22 includes a transfer wire 22a made of a tungsten wire or the like and a shield plate 2 made of a metal plate.
2b. By applying a high voltage to the transfer line 22a, the transfer line 22a causes corona discharge, and the toner image on the photoconductor 1 is transferred onto the recording paper 17.
The toner image transferred onto the recording paper 17 is heated by the heat roller 23 and the pressure roller 24 by a fixing device 25 including a heat roller 23 and a pressure roller 24 having a heat source inside.
The printing is completed by fixing the recording paper 17 with the pressure and heat accompanying the pinching rotation of.

The cleaner portion is composed of a cleaning blade 26 for scraping off the toner 9 remaining on the photoconductor 1 and a toner collecting butt 27 for storing the scraped toner 9, and the photoconductor 1 is located downstream thereof. A static eliminator 28 for electrostatically cleaning the battery is provided.

[0010]

However, in such a conventional non-magnetic one-component developing system, when the environment in which the apparatus is used is high temperature and high humidity, the toner 9 in the toner hopper 7 aggregates due to the temperature rise. In addition to being easier,
Friction heat generated between the thinning roller 29 and the developing roller 10 is applied. The frictional heat causes the toner 9 to melt, and the toner 9 is fused to the thinning roller 29. When the toner 9 is fused to the thinning roller 29, the developing roller 10
There is a problem in that the thinned state of the upper toner 9 is deteriorated, and image unevenness occurs such as vertical streaks in a printed image.

The present invention solves the above-mentioned conventional problems, and provides an image forming apparatus capable of suppressing the generation of frictional heat between a thinning roller and a developing roller according to environmental changes and obtaining a high quality image. The purpose is to do.

[0012]

In order to achieve the above object, the present invention has a toner carrying roller for carrying a toner for developing an electrostatic latent image formed on an image carrier, and a toner storage for storing the toner. Section, a supply member that supplies toner to the toner carrying roller, a layer thickness regulating roller that regulates the layer thickness of the toner carried on the toner carrying roller, and the relative speed of the toner carrying roller and the layer thickness regulating roller as environment. And a control means for changing it in accordance with the change of.

[0013]

According to the present invention, when the environment in which the apparatus is used is changed to high temperature and high humidity, the relative speed between the layer thickness regulating roller and the toner carrying roller is reduced by the above construction, so that the layer thickness regulating roller and the toner carrying roller are supported. It is possible to suppress the generation of frictional heat with the roller.

[0014]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. Here, the same reference numerals are used for the same components as those of the conventional one, and the description thereof will be omitted.

The photosensitive member 1 is a negative charging type OPC having an aluminum drum as a base material and an organic photoconductor coated in a thin film on the outer peripheral surface thereof.

The toner supply roller 6 is formed by forming a conductive foam having a resistance value of 10 ⁶ Ωcm or less around a metal shaft. The toner supply roller 6 supplies the toner 9 to the developing roller 10. It also has a function of scraping off the toner 9 remaining on the developing roller 10 without being developed. A toner supply bias power source 11 is connected to the metal shaft of the toner supply roller 6 via a protection resistor 12.

The thinning roller 29 is formed by forming urethane rubber having a resistance value of 10 ³ to 10 ⁹ Ωcm on the outer circumference of a metal shaft, and is fixed by a thinning roller holding member 30. The thinning roller 29 applies a linear pressure of 80 g to the developing roller 10.
/ Cm to press the surface of the developing roller 10 to 0.5 mg /
A cm ² toner layer is formed. The thinning roller 29
The material is not limited to urethane rubber, but metal, silicon rubber, foam rubber, or the like may be used.

Reference numeral 31 denotes a temperature / humidity sensor installed in the image forming apparatus, which can control the number of revolutions of the thinning roller 29 by reading an environmental change.

The developing roller 10 has a single-layer structure in which a metal shaft is used as a base material and silicon rubber which is a conductive elastic member having a resistance value of 10 ⁶ Ωcm is formed on the outer peripheral surface thereof. A developing bias power source 1 is attached to the metal shaft of the developing roller 10.
4 are connected. The developing roller 10 preferably has a rubber hardness in the range of 30 to 60 degrees, and the surface roughness is preferably 7 μmRz or less because the higher the surface smoothness is, the more uniform the toner thin layer can be formed.

The transfer device 22 is composed of a transfer wire 22a made of a tungsten wire and a metallic shield plate 22b, and the cleaner part is composed of a cleaning blade 26 and a toner recovery butt 27.

Toner 9 is a non-magnetic one-component toner,
Negatively-charged toner is used by uniformly dispersing carbon, wax, charge control agent, etc. in polyester resin. The bias voltage value of the developing bias power source 14 is −300 V, and the bias voltage value of the toner supply bias power source 11 is +300 V.
V, the resistance value of the protection resistor 12 is 22 MΩ.

The operation of the image forming apparatus configured as described above will be described. The photoconductor 1 is uniformly charged to −700 V by the charger 2 and the photoconductor 1 is charged according to an image signal.
Is selectively exposed by the exposure light beam 4 emitted from the exposure optical system 3, whereby the potential of the unexposed portion is -7.
00V, the potential of the exposed part is about -100V,
An electrostatic latent image is formed on the photoconductor 1.

After the toner is agitated by the toner agitating member 8 and conveyed, the toner 9 is supplied by the toner supply roller 6 to the surface of the developing roller 10, which is a toner carrier, and conveyed.
Is regulated in layer thickness by the thinning roller 29 and is triboelectrically charged to form a thin layer state on the outer peripheral surface of the developing roller 10.

The process speed is 96 mm / sec, the peripheral speed of the developing roller 10 is 192 mm / sec, the peripheral speed ratio to the photosensitive member 1 is double, and the peripheral speed of the toner supply roller 6 is 132 mm / sec. When the environment in which the image forming apparatus is used is room temperature and normal humidity (20 ° C., 60%), the peripheral speed of the layer-thinning roller 29 is 40 mm / sec, and the photoconductor 1, the developing roller 10, the layer-thinning roller 29, and The rotation direction of the toner supply roller 6 is the direction of the arrow shown in FIG. 1, and the contact portions are in frictional contact.

Next, when the environment in which the image forming apparatus is used becomes high temperature and high humidity (32.5 ° C., 80%), the temperature / humidity sensor 31 reads and the peripheral speed of the thinning roller 29 is set to 30.
Reduce to mm / sec. As a result, the generation of frictional heat between the developing roller 10 and the layer-thinning roller 29 can be suppressed, the fusion of the toner 9 to the layer-thinning roller 29 and the like can be prevented, and vertical streaks on the developing roller 10 occur. Can be prevented.

Thereafter, the bias voltage applied from the developing bias power source 14 causes the toner 9 to be transferred and adhered to the portion of the photoconductor 1 where the electrostatic latent image is formed, so that the electrostatic latent image is visualized.

Next, a voltage of 1 kV is applied to the transfer line 22a made of a tungsten wire to cause corona discharge, and the image of the toner 9 on the photoconductor 1 is transferred onto the recording paper 17. The image of the toner 9 transferred onto the recording paper 17 is fixed on the recording paper 17 by pressure and heat by a fixing device 25 composed of a heat roller 23 and a pressure roller 24, and printing is completed.

[0028]

As described above, according to the present invention, the toner carrying roller carrying the toner for developing the electrostatic latent image formed on the image carrying body, the toner storing section for storing the toner, and the toner carrying roller are provided. A supply member that supplies toner, a layer thickness regulating roller that regulates the layer thickness of the toner carried on the toner carrying roller, and a relative speed between the toner carrying roller and the layer thickness regulating roller are changed according to a change in environment. By providing the control means, when the environment in which the apparatus is used is changed to high temperature and high humidity, the relative speed between the layer thickness regulating roller and the toner carrying roller is reduced to reduce the layer thickness regulating roller and the toner carrying roller. It is possible to suppress the generation of frictional heat with the toner, prevent fusion of the toner and the like, and obtain a good image without image unevenness due to vertical streaks.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional image forming apparatus.

[Explanation of reference numerals] 1 photoconductor 2 charger 3 exposure optical system 4 exposure light beam 5 developing device 6 toner supply roller 7 toner hopper 8 toner stirring member 9 toner 10 developing roller 11 toner supply bias power supply 12 protective resistance 14 development bias power supply 16 Recording paper cassette 17 Recording paper 18 Paper feed roller 19 Conveying roller 20 Registration roller 22 Transfer device 23 Heat roller 24 Pressure roller 25 Fixing device 26 Cleaning blade 27 Toner collecting bat 28 Static eliminator 29 Thinning roller 30 Thinning roller holding Material 31 Temperature and humidity sensor

Claims (3)

[Claims] 1. A toner carrying roller for carrying a toner for developing an electrostatic latent image formed on an image carrying body, a toner storing section for storing toner, and a toner for storing the toner in the toner storing section on the toner carrying roller. A supply member for supplying, a layer thickness regulating roller for regulating the layer thickness of the toner carried on the toner carrying roller, and a relative speed of the toner carrying roller and the layer thickness regulating roller are changed according to environmental changes. An image forming apparatus comprising: a control unit. 2. The image forming apparatus according to claim 1, wherein the control means changes a relative speed between the toner carrying roller and the layer thickness regulating roller according to a change in temperature. 3. The image forming apparatus according to claim 1, wherein the control means changes a relative speed between the toner carrying roller and the layer thickness regulating roller according to a change in humidity.