JP2000206766A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the charging potential of the toner-image carrier of an image forming device. SOLUTION: An image forming device has a toner-image carrier 1 for forming an electrostatic latent image thereon, a charger 2 for uniformly charging the toner-image carrier 1 to specific potential, a developing roller 8 for forming a toner image thereon by attaching toner 12 to the electrostatic latent image, a current measurement part 13 for measuring a current flowing in the developing roller 8 owing to the charging of the toner-image carrier 1, an charging-potential computation part 14 for obtaining charging potential for the toner-image carrier 1 from a current value measured by the current measurement part 13, and a voltage application part 17 for applying a voltage to the charger 2 so that the electrification potential of the toner-image carrier 1 reaches the charging potential obtained by the charging-potential computation part 14.

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 for forming an image by an electrophotographic recording technique.

[0002]

2. Description of the Related Art In recent years, toner-type image forming apparatuses capable of forming clear images with excellent resolution, such as laser printers, have become widespread. Among them, an image forming apparatus using a contact one-component developing method is very suitable for reducing the size and weight of the apparatus and reducing the number of components due to its configuration.

Here, a conventional image forming apparatus will be described. FIG. 5 is a schematic view showing a conventional one-component developing type image forming apparatus, and FIG. 6 is an explanatory view showing a charger attached to the image forming apparatus of FIG.

As shown in FIG. 5, the image forming apparatus includes a toner image carrier 1 on which an electrostatic latent image is formed and a developing device 4.

At a predetermined position on the outer periphery of the toner image carrier 1, a charger 2 for uniformly charging the toner image carrier 1 is provided.

The developing device 4 has a housing 15 in which the toner 12 is stored. In this housing 15,
A developing roller 8 for forming a toner image by attaching toner 12 to an electrostatic latent image formed on toner image carrier 1, and a toner supply roller 9 for supplying toner 12 to developing roller 8
Is rotatably mounted. Further, the developing roller 8
Thickness regulating blade 11 for regulating the toner 12 supplied to the outer peripheral surface of the developing roller 8 to a predetermined thickness.
Is provided. Further, a toner stirring blade 10 that stirs the toner 12 in the housing 15 and sends it to the toner supply roller 9 is provided.

As shown in FIG. 6, the charger 2 includes a charge wire 2a to which a high voltage (current) is applied, and a grid 2b arranged around the charge wire 2a. The charge wire 2a is made of a tungsten wire having a diameter of about 50 μm or a tungsten wire plated with gold. The charging potential of the toner image carrier 1 is controlled to the potential of the grid 2b.

According to such an image forming apparatus, the laser is turned on / off by the information of the image sent from the host computer, and the electrostatic charge is placed on the toner image carrier 1 uniformly charged by the charger 2. A latent image is formed.

On the other hand, in the developing device 4, the toner 12 in the housing 15 is stirred by the toner stirring blade 10 and conveyed to the toner supply roller 9. The toner 12 transported to the toner supply roller 9 is
To the developing roller 8. Then, the toner 12 supplied to the developing roller 8 is regulated to a predetermined layer thickness by the layer thickness regulating blade 11, whereby a uniform toner layer is formed on the developing roller 8.

When the toner adheres to the electrostatic latent image on the toner image carrier 1 from the developing roller 8, a toner image is formed.

[0011]

As described above, the toner image carrier is charged by the charger. The charging potential of the toner image carrier fluctuates due to deterioration of the toner image carrier itself, a change in environment, and the like. If the charging potential of the toner image carrier fluctuates, there is a problem that the density, fog, and reproducibility of fine lines of the output image are affected.

Accordingly, an object of the present invention is to provide an image forming apparatus capable of stabilizing the charging potential of a toner image carrier.

[0013]

In order to solve this problem, an image forming apparatus according to the present invention comprises a toner image carrier on which an electrostatic latent image is formed, and a toner image carrier having a uniform potential. A charging device, a developing roller that forms a toner image by attaching toner to the electrostatic latent image, a current measuring unit that measures a current flowing through the developing roller by charging the toner image carrier, and a current measuring unit. A charging potential calculation unit for calculating the charging potential of the toner image carrier from the measured current value, and a voltage for applying the charging potential of the toner image carrier to the charging potential determined by the charging potential calculation unit is applied to the charger. And a voltage application unit.

This makes it possible to stabilize the charging potential of the toner image carrier.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, there is provided a toner image carrier on which an electrostatic latent image is formed, and a charger for uniformly charging the toner image carrier to a predetermined potential. A developing roller that forms a toner image by attaching toner to the electrostatic latent image, a current measuring unit that measures a current flowing through the developing roller due to charging of the toner image carrier, and a current value measured by the current measuring unit. A charging potential calculating section for calculating a charging potential of the toner image carrier; and a voltage applying section for applying a voltage to the charger such that the charging potential of the toner image carrier becomes the charging potential determined by the charging potential calculating section. This is an image forming apparatus, and has an operation of stabilizing the charging potential of the toner image carrier.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

FIG. 1 is a schematic view showing an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a schematic view showing a main part of the image forming apparatus shown in FIG. 1, and FIG. FIG. 4 is a block diagram showing a stabilizing circuit, and FIG. 4 is a flowchart showing a charging stabilizing operation in the image forming apparatus of FIG.

As shown in FIG. 1, the image forming apparatus includes a toner image carrier 1 made of a photosensitive drum on which an electrostatic latent image is formed. The outer peripheral surface of the toner image carrier 1 is coated with an organic photoconductive material.

Around the toner image carrier 1, a charger 2 for uniformly charging the toner image carrier 1, a laser is turned on / off by information from a host computer, and the toner image carrier 1 is placed on the toner image carrier 1. An exposure system 3 for forming an electrostatic latent image, a developing device 4 for transferring toner 12 contributing to development to a portion of the electrostatic latent image and developing the electrostatic latent image into a visible image, and a toner image carrier 1 A transfer roller 5 for transferring the formed toner image to a sheet (not shown), a cleaner 6 for removing the toner 12 remaining on the outer peripheral surface of the toner image carrier 1, and a toner image carrier 1 formed by removing electricity. The static eliminators 7 for erasing the formed electrostatic images are sequentially arranged along the rotation direction of the toner image carrier 1.

The developing device 4 for visualizing the electrostatic latent image formed on the toner image carrier 1 to form a toner image 16 has a housing 15 for accommodating a toner 12 as shown in FIG. ing. In the housing 15, a conductive roller is wound around a metal shaft and a toner 12 is attached to an electrostatic latent image to form a toner image 16. A toner supply for supplying the toner 12 to the developing roller 8 is provided. Roller 9
Are rotatably mounted together. Further, a layer thickness regulating blade 11 which is pressed against the developing roller 8 and regulates the toner 12 supplied to the outer peripheral surface of the developing roller 8 to a predetermined thickness is provided. Further, a toner stirring blade 10 that stirs the toner 12 in the housing 15 and sends it to the toner supply roller 9 is provided.

The developing roller 8 is provided with a current measuring section 13 for measuring the amount of current flowing through the developing roller 8, which is connected to the ground. The current measuring section 13 is connected to a charging potential calculating section 14 for calculating a current value measured by the current measuring section 13. The charging potential calculation unit 14 is connected to a voltage application unit 17 that applies a current and a voltage to the charge wire 2a and the grid 2b of the charger 2 according to the current value obtained from the charging potential calculation unit 14. Have been. Therefore, the charging potential of the toner image carrier 1 is controlled by the voltage applying unit 17.

Further, as shown in FIG. 3, the image forming apparatus includes a current-voltage converter 18 for converting the current of the developing roller 8 measured by the current measuring unit 13 into a voltage. A / D converter 19 for converting the voltage value of the analog data into digital data, and a charging potential calculation for calculating the charging potential of the toner image carrier 1 in consideration of the temperature and humidity data in the data from the A / D converter 19. A D / A converter 21 for converting the charging potential of digital data, which is the result of calculation by the charging potential calculator 14, into analog data;
A voltage application unit 17 for generating a high voltage for charging the toner image carrier 1 based on the analog data received from the conversion unit 21 is provided. And the charger 2
Is applied with a voltage from the voltage application unit 17.

The operation of the image forming apparatus configured as described above will be described. When the image formation is started, the laser is turned on / off according to image information sent from the host computer, and the exposure system 3 forms an electrostatic latent image on the toner image carrier 1. When the toner 12 supplied from the developing device 4 adheres to the electrostatic latent image, a visible image, that is, a toner image 16 is formed.

At approximately the same time when the development of the toner image 16 on the toner image carrier 1 is completed and the sheet is conveyed to the transfer roller 5, the transfer roller 5
Contacted. Then, by applying a predetermined level of voltage, the toner image 16 on the toner image carrier 1 is transferred to a sheet.

Thereafter, the toner image 16 is fixed on the sheet by a fixing device (not shown), and the image formation is completed.

On the other hand, the residual toner image that has not been transferred is removed from the toner image carrier 1 by the cleaner 6, and the charge of the toner image carrier 1 is removed by the charge remover 7. Thus, the toner image carrier 1 is in a standby state for forming a new image.

Here, the charging stabilizing operation in such an image forming apparatus will be described with reference to FIG.

When the toner image carrier 1 is charged, a current flows through the developing roller 8 (step S1). And
The current amount at this time is measured by the current measuring unit 13 (step S2).

When the current flowing through the developing roller 8 is measured, it is converted into a voltage by the current-voltage converter 18 (step S3), and is further converted into digital data by the AD converter 19 (step S4). ).

Next, the charging potential of the toner image carrier 1 is determined by the charging potential calculation unit 14 (step S5), and this is calculated by DA.
The conversion unit 21 converts the data into analog data (step S
6).

Then, a voltage based on the analog data is generated in the voltage application section 17 (step S7), and this voltage is applied to the charger 2 to uniformly bring the toner image carrier 1 to a predetermined potential. Be charged.

As described above, according to the image forming apparatus of the present embodiment, the developing roller 8 is charged by charging the toner image carrier 1.
Is measured by a current measuring unit 13, the charging potential of the toner image carrier 1 is determined by a charging potential calculating unit 14 from the current value, and the voltage applying unit 17 is set so that the toner image carrier 1 has the charging potential. A predetermined voltage is applied to the charger 2 so that the charging potential of the toner image carrier 1 can be stably maintained even when the toner image carrier 1 has deteriorated or the sensitivity has changed in the environment. Will be possible.

[0033]

As described above, according to the present invention, the charging potential of the toner image carrier is determined from the current flowing through the developing roller, and a voltage is applied to the charger so that the toner image carrier has the charging potential. As a result, an effective effect of being able to stably stabilize the charging potential of the toner image carrier is obtained.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram illustrating a main part of the image forming apparatus of FIG. 1;

FIG. 3 is a block diagram showing a charging stabilization circuit in the image forming apparatus of FIG. 1;

FIG. 4 is a flowchart showing a charging stabilization operation in the image forming apparatus of FIG. 1;

FIG. 5 is a schematic view showing a conventional one-component developing type image forming apparatus.

FIG. 6 is an explanatory view showing a charger attached to the image forming apparatus of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Toner image carrier 2 Charger 8 Developing roller 12 Toner 13 Current measuring part 14 Charge potential calculating part 17 Voltage applying part

Claims (1)

[Claims] 1. A toner image carrier on which an electrostatic latent image is formed, a charger for uniformly charging the toner image carrier to a predetermined potential, and a toner for adhering toner to the electrostatic latent image A developing roller that forms an image; a current measuring unit that measures a current flowing through the developing roller by charging the toner image carrier; and a charging potential of the toner image carrier from a current value measured by the current measuring unit. A charging potential calculation unit to be obtained; and a voltage application unit that applies a voltage to the charger so that the charging potential of the toner image carrier becomes the charging potential obtained by the charging potential calculation unit. Image forming device.