JPH04264472A - Toner concentration controlling method and controller for electrophotographic device - Google Patents

Abstract

PURPOSE:To control toner concentration considering the fatigue of developer. CONSTITUTION:The target value of the magnetic permeability of the developer is corrected based on the changing value of the magnetic permeability corresponding to the degree of the fatigue of the developer. A sensor means 20 to detect the magnetic permeability of the developer S, a calculating means 21 to calculate the toner concentration in the developer S based on the detected value of the sensor means 20, a memory means 25 storing the changing value of the magnetic permeability corresponding to the degree of the fatigue of the developer S, a counting means 26 to count an achievement value corresponding to the degree of the fatigue of the developer S, a selecting means 24 to select a desired changing value from the memory means 25 based on the achievement value inputted from the counting means 26, an arithmetic calculating means 23 to correct the target value based on the changing value inputted from the selecting means 24, and a controlling means 22 to adjust the toner concentration in such a state where a calculated value inputted from the calculating means 21 keeps the corrected value inputted from the arithmetic calculating means 23 are provided.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention mainly detects the magnetic permeability of a two-component developer, calculates the toner concentration in the developer from the detected magnetic permeability, and controls the toner concentration to keep it constant. The present invention relates to a toner density control method and control device for an electrophotographic apparatus.

0002

2. Description of the Related Art Since the toner concentration in a two-component developer directly affects the quality of recorded images, electrophotographic apparatuses are equipped with a control function to keep the toner concentration constant. In a conventional electrophotographic apparatus, a sensor detects the magnetic permeability of a developer made of toner and carrier, calculates toner concentration from the detected magnetic permeability, and controls the magnetic permeability to maintain a constant value.

[0003] This is because there is a correlation between the toner concentration in the developer and the magnetic permeability of the developer; when the toner concentration is high, the magnetic permeability of the developer decreases, and when the toner concentration is low, the magnetic permeability increases. It is. Therefore, for example, if the toner density is set to 5w
When maintaining the developer at t%, the magnetic permeability of the developer with respect to this 5wt% is measured, and this measured value is set as the target value. When the magnetic permeability detected by the sensor becomes larger than the target value, toner is replenished until the target value is reached, while when the permeability becomes smaller than the target value, toner supply is stopped and toner is removed. Concentration is controlled.

FIG. 3 shows a flowchart of toner density control by a conventional electrophotographic apparatus. This control is started by selecting the toner density control mode. First, the sensor detects the magnetic permeability of the developer multiple times (x times), and calculates the toner concentration by averaging the detected values (step S11
). The calculated value of the toner density is compared with the target value (step S12), and if the calculated value is larger than the target value, toner is replenished (step S13).On the other hand, if the calculated value is smaller than the target value, the toner is replenished (step S13). without replenishing toner.
Returning to the sensing process (step S11), toner concentration control is continued.

[0005]

By the way, the developer tends to become fatigued due to mutual friction, moisture absorption, etc., and when this fatigue occurs, the magnetic permeability fluctuates. Therefore, even if the toner concentration is constant, the measured magnetic permeability changes and deviates from the target value. As a result, toner is replenished or not replenished even when it is not necessary, resulting in the problem that the actual toner concentration deviates from the target value, resulting in an undesirable toner concentration.

The present invention has been made in view of the above problems, and provides a toner concentration control method and a control device for an electrophotographic apparatus, which are capable of controlling toner concentration in consideration of developer fatigue. That is its purpose.

[0007]

[Means for Solving the Problem] In order to achieve the above object, the invention of claim 1 detects the magnetic permeability of the developer, calculates the toner concentration in the developer from the detected magnetic permeability, and calculates the calculated value. In a toner concentration control method for an electrophotographic apparatus that controls the magnetic permeability of a developer to maintain a target value corresponding to a predetermined toner concentration, the target value is based on a change value of magnetic permeability corresponding to the degree of fatigue of the developer. It is characterized in that it is corrected by

[0008] Furthermore, the invention of claim 2 detects the magnetic permeability of the developer, calculates the toner concentration in the developer from the detected magnetic permeability, and calculates the toner concentration of the developer corresponding to a predetermined toner concentration by this calculated value. A toner concentration control device for an electrophotographic apparatus that controls magnetic permeability to maintain a target value includes a sensor means for detecting magnetic permeability of a developer, and calculates the toner concentration in the developer based on a detected value of the sensor means. a calculation means, a memory means in which a change value of magnetic permeability corresponding to the degree of fatigue of the developer is stored, a count means for counting a result value corresponding to the degree of fatigue of the developer, and a result inputted from the count means. a selection means for selecting a desired change value from the memory means based on the value, a calculation means for correcting the target value based on the change value input from the selection means, and a calculated value input from the calculation means; It is characterized by comprising a control means for adjusting the toner concentration so as to maintain the correction value inputted from the calculation means.

[0009]

[Operation] The target value of the magnetic permeability of the developer corresponding to a predetermined toner concentration is corrected by the change value of the magnetic permeability corresponding to the degree of fatigue of the developer. That is, the correction value that takes into account the degree of fatigue of the developer becomes the final target value, and the toner density is controlled so that the calculated value of the detected toner density maintains this value.

0010

Embodiment FIG. 1 is an overall configuration diagram of an electrophotographic apparatus to which an embodiment of the present invention is applied. An optical unit 2 is disposed above the optical system 1. The optical unit 2 exposes the photosensitive drum 1 to light in the main scanning direction, and by exposing the photosensitive drum 1 to light in the main scanning direction and rotating the photosensitive drum 1 in the sub-scanning direction (direction of arrow A).
An electrostatic latent image is formed on the surface. Around the photosensitive drum 1, a charging charger 3, a developing device 4, a transfer charger 5, a separation charger 6, a first static eliminating lamp 7a, a cleaning device 8, and a second static eliminating lamp 7b are arranged in order along the rotation direction of the photosensitive drum 1. has been done. The recording paper P is fed from the right side to the left side of the photosensitive drum 1 to record an image.
A fixing device 9 is disposed on the paper feeding path of the recording paper P.

The above-mentioned constituent members will be explained below along with their functions. The charger 3 uniformly charges the surface of the photosensitive drum 1 before exposure by corona discharge. The charged photosensitive drum 1 is exposed to image light from the optical unit 2 to form an electrostatic latent image on its surface. The developing device 4 is a case 1 filled with a two-component developer S consisting of toner and carrier.
0, and a developing roller 11 that is rotationally driven within a case 10. The developing device 4 also includes a toner cartridge 12 that stores the toner T, and a case 10 that stores the toner T.
It has a sponge roller 13 for supplying the toner T and a scraper 14 for stirring the toner T and carrier, and the required amount of toner is supplied from the toner cartridge 12 into the case 10 by controlled rotation of the sponge roller 13, and the scraper 14, the toner T and carrier are stirred. In addition, as the developing roller 11 rotates in close proximity to the photosensitive drum 1, the toner T in the case 10 is supplied to the photosensitive drum 1 by the action of the carrier. As a result, the electrostatic latent image on the surface of the photosensitive drum 1 is developed and visualized.

A recording paper P is synchronously supplied to the photosensitive drum 1, and a transfer charger 5 performs corona discharge to transfer the developed image on the surface of the photosensitive drum 1 onto the recording paper P. The separation charger 6 separates the recording paper P from the photosensitive drum 1 by corona discharge. The separated recording paper P is conveyed along the paper feed path and reaches the fixing device 9. The fixing device 9 has a heater 15
The heat roller 16 with built-in and the heat roller 1
6 and a pressure roller 17 in rolling contact with the recording paper P.
The image is fixed on the recording paper P by being heated and pressed by passing between these rollers 16 and 17.

On the other hand, the photosensitive drum 1 after the image transfer is
After being neutralized by the static eliminating lamp 7a, as it rotates, it approaches the cleaning brush 18 of the cleaning device 8, and is further neutralized by the second static eliminating lamp 7b, completing one rotation.

The case 10 is filled with a two-component developer S consisting of toner T and carrier, and a magnetic permeability sensor (sensor means) 20 is inserted into the case 10. The magnetic permeability sensor 20 is provided so that its detection end faces the developer S, and detects the magnetic permeability of the developer S. This magnetic permeability sensor 20 includes a toner concentration calculator (calculation means) 21.
The toner concentration calculation device 21 is further connected to a controller (control means) 22. The detected values from the magnetic permeability sensor 20 are input to the toner concentration calculator 21, the average value of the detected values is calculated, and the concentration of the toner T in the developer S is calculated from this average value.
2 is output.

A selector (selecting means) 24 is connected to the controller 22 via a calculating unit (calculating means) 23. The magnetic flux change value is selected from the memory (memory means) 25 and output to the arithmetic unit 23. The change value is set in advance based on experimental or empirical data, and is stored in memory. The desired change value is selected by a select signal (actual value) from a counter (counting means) 26 that is input to the selector 24. In general, the actual level of developer fatigue changes depending on the number of times an image is recorded (i.e., the number of times the copy switch is pressed), so this number of recordings is input to the counter 26, and based on this, selection is made as an actual value. A signal is output to the selector 23. The change value selected from the memory (memory means) 25 by this selection signal is input to the arithmetic unit 23. The arithmetic unit 23 corrects the set target value of toner density using this change value, and outputs this correction value to the controller 22 as the final target value.

The controller 22 receives the correction value from the arithmetic unit 23 and the calculated value from the toner concentration calculator 21, and controls the amount of supplied toner so that the calculated value maintains the corrected value. That is, the controller 22 acts on a drive section (not shown) of the sponge roller 13 to control its rotation, thereby controlling the amount of toner supplied.

FIG. 2 shows a flow chart of this toner density control. This flowchart starts when the electrophotographic apparatus is placed in the toner density control mode. First, the magnetic permeability sensor 20 detects the magnetic permeability of the developer multiple times (x times),
The toner concentration calculator 21 calculates the toner concentration from the average value of the detected values (step S1). On the other hand, the change value of magnetic permeability corresponding to the degree of fatigue of the developer S is sent to the arithmetic unit 23 via the selector 24. input from the memory 25 (step S2
), where the target value is corrected by the change value. This correction value (final target value) is set to be the true toner density, taking into account the factor due to fatigue (step S3). Then, the controller 22 compares the calculated value from the toner concentration calculator 21 with the correction value from the arithmetic unit 23 as a target (step S4), and if the correction value is smaller than the calculated value (that is, if the toner density is light) ) performs replenishment from toner (step S5). Also, if the correction value is larger than the target value (i.e., if the toner density is higher than the predetermined density)
returns to START without replenishing toner. Therefore, by the above control, it is possible to adjust the toner density while eliminating the influence of fatigue of the developer S, and thus it is possible to record an image of good quality.

[0018]

As described above, the present invention makes it possible to control the toner density by correcting the magnetic permeability of the developer detected by the sensor so as to take into account the fatigue level of the developer. Even if this occurs, the toner density can be accurately adjusted to the target density, and the toner density can be made to a good density.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an electrophotographic apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a flowchart of toner density control.

FIG. 3 is a flowchart of conventional toner density control.

[Explanation of symbols]

20...Magnetic permeability sensor 21...Toner concentration calculator 22...Controller 23... Arithmetic unit 24...Selector 25...Memory 26...Counter T...Toner S...Developer

Claims (2)

[Claims] Claim 1: Detecting the magnetic permeability of the developer, calculating the toner concentration in the developer from the detected magnetic permeability, and maintaining this calculated value at a target value of the magnetic permeability of the developer corresponding to a predetermined toner concentration. A toner density control method for an electrophotographic apparatus, wherein the target value is corrected based on a change value of magnetic permeability corresponding to a degree of fatigue of the developer. . 2. Detect the magnetic permeability of the developer, calculate the toner concentration in the developer from the detected magnetic permeability, and keep this calculated value at a target value of the developer magnetic permeability corresponding to a predetermined toner concentration. In a toner concentration control device for an electrophotographic apparatus, a sensor means for detecting the magnetic permeability of a developer, a calculation means for calculating a toner concentration in the developer based on a detected value of the sensor means, and a developer a memory means for storing a change value of magnetic permeability corresponding to the degree of fatigue of the developer; a counting means for counting an actual value corresponding to the degree of fatigue of the developer;
a selection means for selecting a desired change value from the memory means based on the actual value inputted from the counting means; and a calculation means for correcting the target value based on the change value inputted from the selection means. . A toner density control device for an electrophotographic apparatus, comprising: a control unit that adjusts toner density so that the calculated value input from the calculation unit maintains the correction value input from the calculation unit.