JPH04336571A - Toner density control method for electrophotographic device and control device therefor - Google Patents

Abstract

PURPOSE:To provide a toner density control method and a control device for an electrophotographic device having the capability of performing toner density control in consideration of the temperature or humidity of developer. CONSTITUTION:A toner density control device for an electrophotographic device is equipped with a detection means 20 to detect the magnetic permeability of developer S, a calculation means 21 to calculate the density of toner in the developer S on the basis of a value detected with the means 20, and a memory means 25 to store the variations of the magnetic permeability corresponding to the temperature or humidity of the developer S. Furthermore, there are equipped a temperature measurement means 26 to detect the temperature of the developer S, a selection means 24 to select a desired variation value from the memory means 26 on the basis of an actual value entered from the means 26, an arithmetic means 23 to correct a target value on the basis of a variation value entered from the means 24, and a control means 22 to adjust toner density for a calculated value entered from the means 21 to maintain a correction value entered from the means 23.

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.

This is because, as shown in FIG. 5, 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. This is because they have a relationship. Therefore, for example, when maintaining the toner concentration at 3.5wt%, this 3.5w
2V, which is the developer magnetic permeability sensor output with respect to t%, is set as the target value. When the permeability sensor output detected by the sensor is larger than 2V, toner is replenished until it reaches 2V, while when it is smaller than 2V, toner density is controlled by stopping toner replenishment. ing.

FIG. 6 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]

However, due to changes in temperature or humidity, the flowability of the developer as a powder changes. For example, as shown in FIG. 7, even if the toner concentration of the developer is the same, the magnetic permeability sensor output varies depending on the temperature change. Therefore, in conventional toner concentration control, the toner concentration changes due to changes in temperature and humidity, resulting in an undesirable toner concentration.

Another problem is that even if the toner concentration is constant, the print quality changes due to changes in humidity. This is because the toner in the developer is charged by friction with the carrier, and the amount of charge on the toner changes depending on changes in humidity.

The present invention has been made in view of the above-mentioned problems, and provides a toner density control method and control device for an electrophotographic apparatus that can control toner density based on the temperature or humidity of the developer. That is its purpose.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the first invention detects the magnetic permeability of a developer, calculates the toner concentration in the developer from the detected magnetic permeability, and sets this calculated value to a predetermined value. In a toner concentration control method for an electrophotographic apparatus, the target value is controlled to maintain a target value of magnetic permeability of a developer corresponding to a toner concentration. to correct.

The second invention also includes a detection means for detecting the magnetic permeability of the developer, a calculation means for calculating the toner concentration in the developer based on the detected value of the detection means, and a temperature characteristic of the developer. a storage means in which a change value of magnetic permeability corresponding to the change in magnetic permeability is stored; a temperature measurement means for measuring the temperature of the developer; and a desired change value from the storage means based on the measurement value inputted from the temperature measurement means. A selection means for selecting, a calculation means for correcting the target value based on the change value input from the selection means, and a calculation means for adjusting the toner so that the calculated value input from the calculation means maintains the correction value input from the calculation means. Control means for adjusting the concentration are provided.

Furthermore, the third invention detects the magnetic permeability of the developer, calculates the toner concentration in the developer from the detected magnetic permeability, and this calculated value is the permeability of the developer corresponding to a predetermined toner concentration. In a toner density control method for an electrophotographic device that controls the magnetic permeability to maintain a target value, the target value is changed to a change value of magnetic permeability corresponding to the humidity characteristics of the developer and a change value of the toner charge amount corresponding to the humidity characteristics. Correct based on.

[0011] The fourth invention also includes a detection means for detecting the magnetic permeability of the developer, a calculation means for calculating the toner concentration in the developer based on the detected value of the detection means, and a humidity characteristic of the developer. a storage means storing a change value of magnetic permeability corresponding to the change value and a change value of the toner charge amount corresponding to the humidity characteristic;
a humidity measuring means for measuring the humidity of the developer; a selecting means for selecting a desired change value from the storage means based on the measured value inputted from the humidity measuring means; , a calculation means for correcting the target value, and a control means for adjusting the toner concentration so that the calculated value input from the calculation means maintains the correction value input from the calculation means.

0012

According to the first and second inventions, 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 temperature of the developer. That is, the correction value that takes into account the temperature characteristics 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.

According to the third and fourth inventions, the target value of magnetic permeability of the developer corresponding to a predetermined toner concentration is
Correction is made using a change value of magnetic permeability corresponding to the humidity characteristics of the developer and a change value of the toner charge amount corresponding to the humidity characteristics. That is, the correction value that takes into account the humidity characteristics 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.

[0014]

[Example] Regarding an example of the first and second inventions,
This will be explained using FIGS. 1 and 2. FIG. 1 is an overall configuration diagram of an electrophotographic apparatus to which this embodiment is applied. In the same figure,
A photosensitive drum 1, which is a photosensitive member, is rotationally driven in the direction of arrow A, and an optical unit 2 is disposed above the photosensitive drum 1. The optical unit 2 exposes the photosensitive drum 1 to light in the main scanning direction, and electrostatic charge is generated on the surface of the photosensitive drum 1 by this exposure in the main scanning direction and rotation of the photosensitive drum 1 in the sub-scanning direction (direction of arrow A). A latent image is formed. 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 this order. The recording paper P is fed from the right side to the left side of the photosensitive drum 1, and an image is recorded on the photosensitive drum 1. A fixing device 9 is disposed on the 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 a paper feeding 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 that rolls into 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 (detection 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. A toner concentration calculator (calculating means) 21 is connected to the magnetic permeability sensor 20, and the toner concentration calculating device 21 is further connected to a controller (controlling 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.
is output to.

Further, a selector (selection means) 24 is connected to the controller 22 via a calculation unit (calculation means) 23, and the selector (selection means) 24 selects a magnetic permeability corresponding to the temperature of the developer S. Memory (storage means) 2 for the change value of
5 and outputs it to the arithmetic unit 23. The change value is set in advance based on experimental or empirical data, and is stored in the memory 25. The desired change value is selected by a selection signal (actual value) from the temperature detector (temperature measuring means) 26 that is input to the selector 24. A thermistor 27 whose detection end faces the developer S is connected to the temperature detector (temperature measuring means) 26, and detects the temperature of the developer S. The detected temperature data is output to the selector 23 as a selection signal. The change value selected from the memory (storage means) 25 by this selection signal is input to the arithmetic unit 23. Arithmetic unit 2
In step 3, the set target value of toner density is corrected by this change value, and this correction value is output to the controller 22 as the final target value.

The correction value from the calculator 23 and the calculated value from the toner concentration calculator 21 are input to the controller 22, and the amount of supplied toner is controlled 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 flowchart 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), while the change value of the magnetic permeability corresponding to the temperature of the developer S is stored in the memory via the selector 24 in the arithmetic unit 23. 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 temperature change (step S3). and,
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, when the toner density is light), , replenishment from toner is performed (step S5). Furthermore, if the correction value is larger than the target value (that is, if the toner density is greater than or equal to the predetermined density), the process returns to START without toner replenishment. Therefore, with the above control, it is possible to adjust the toner density while removing the influence of temperature changes of the developer S, so that it is possible to record an image of good quality.

Next, an embodiment of the third and fourth inventions will be explained using FIGS. 3 and 4. FIG. 3 is an overall configuration diagram of an electrophotographic apparatus to which this embodiment is applied. This overall configuration diagram is almost the same as the overall configuration diagram in FIG.
The difference is that 9 is provided. Then, the detection data from the humidity detector (humidity measuring means) 28 is sent to the computing unit 2.
3, and the toner density is corrected in accordance with the humidity characteristics, which is a feature of this embodiment. in particular,
A change value of the magnetic permeability corresponding to the humidity of the developer S and a change value of the toner charge amount corresponding to the humidity characteristic are selected from the memory 25 by the selector 24 and output to the calculator 23. These change values are selected based on various data such as experiments or experiences, and are stored in the memory 25 in addition to experimental evaluation data for determining print quality. Then, selection of a desired change value is performed by a selection signal (actual value) from a humidity detector (humidity measuring means) 28 that is input to the selector 24. A humidity sensor 29 whose detection end faces the developer S is connected to the humidity detector (humidity measuring means) 28 and detects the humidity of the developer S. The detected humidity data is output to the selector 23 as a selection signal. The change value selected from the memory 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 correction value from the arithmetic unit 23 and the calculated value from the toner concentration calculator 21 are input to the controller 22, and the amount of supplied toner is controlled 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. 4 shows a flowchart 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), while the calculator 23 calculates the change value of magnetic permeability corresponding to the humidity of the developer S and the humidity characteristics of the toner charge amount. A change value corresponding to the change value is input from the memory 25 via the selector 24 (step S2), and the target value is corrected by the change value. This is because the developer S, which is a two-component developer, charges the toner by friction between the carrier and the toner, so when the humidity increases, the toner charge amount decreases, and when the humidity decreases, the toner charge amount increases. The target value is corrected based on the change value due to such humidity characteristics. This correction value (final target value) is set to be the true toner density, taking into account the factor due to temperature change (step S3). Then, the controller 22 compares the calculated value from the toner concentration calculator 21 with the correction value from the calculator 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 concentration is above a predetermined concentration), the process returns to START without toner replenishment. Therefore, with the above control, it is possible to adjust the toner density while removing the influence of temperature changes of the developer S, so that it is possible to record an image with good image quality.

In this embodiment, the temperature detection means and the humidity detection means are explained as separate embodiments, but the present invention is naturally applicable to a control device equipped with both of these detection means. Ru. In this embodiment, correction is made based on the most appropriate value corresponding to each detection means.

[0026]

[Effects of the Invention] As explained in detail above, in the first and second inventions, the toner concentration is corrected based on the magnetic permeability of the developer detected by the sensor so as to take into account the temperature characteristics of the developer. Therefore, even if there is a temperature change in the developer, the toner concentration can be accurately adjusted to the target concentration, and the toner concentration can be maintained at a good concentration.

Further, according to the third and fourth inventions, the toner density can be controlled by correcting the magnetic permeability of the developer detected by the sensor so as to take into account the humidity characteristics of the developer. Even if there is a humidity change in the agent, the toner concentration can be accurately adjusted to the target concentration, and the toner concentration can be maintained at a good concentration.

[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 configuration diagram of an electrophotographic apparatus to which an embodiment of the present invention is applied.

FIG. 4 is a flowchart of toner density control.

FIG. 5 is a diagram showing the relationship between the toner concentration in the developer and the magnetic permeability of the developer.

FIG. 6 is a flowchart of conventional toner density control.

FIG. 7 is a diagram showing the relationship between developer temperature and developer magnetic permeability.

[Explanation of symbols]

20...Magnetic permeability sensor 21...Toner concentration calculator 22...Controller 23... Arithmetic unit 24...Selector 25...Memory 26...Temperature detector 27...Thermistor T...Toner S...Developer

Claims (4)

[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 concentration control method for an electrophotographic apparatus, wherein the target value is corrected based on a change value of magnetic permeability corresponding to the temperature characteristics 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, the toner concentration control device includes a detection means for detecting magnetic permeability of a developer, a calculation means for calculating a toner concentration in the developer based on a detected value of the detection means, and a developer. a storage means in which a change value of magnetic permeability corresponding to the temperature characteristic of the developer is stored; a temperature measurement means for measuring the temperature of the developer; and a temperature measurement means for measuring the temperature of the developer. a selection means for selecting a desired change value; a calculation means for correcting the target value based on the change value inputted from the selection means; and a calculation means inputted from the calculation means; 1. A toner density control device for an electrophotographic apparatus, comprising: a control means for adjusting toner density so as to maintain the corrected correction value. 3. 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 developer magnetic permeability corresponding to a predetermined toner concentration. In the toner density control method for an electrophotographic apparatus, the target value is corrected based on a change value of magnetic permeability corresponding to the humidity characteristics of the developer and a change value of the toner charge amount corresponding to the humidity characteristics. A toner density control method for an electrophotographic device, characterized in that: 4. The magnetic permeability of the developer is detected, the toner concentration in the developer is calculated from the detected magnetic permeability, and this calculated value maintains a target value of the magnetic permeability of the developer corresponding to a predetermined toner concentration. In a toner concentration control device for an electrophotographic apparatus, the toner concentration control device includes a detection means for detecting magnetic permeability of a developer, a calculation means for calculating a toner concentration in the developer based on a detected value of the detection means, and a developer. a storage means that stores a change value of magnetic permeability corresponding to the humidity characteristic of the toner and a change value of the toner charge amount corresponding to the humidity characteristic; a humidity measuring means for measuring the humidity of the developer; and an input from the humidity measuring means. a selection means for selecting a desired change value from the storage means based on the measured value input from the selection means; a calculation means for correcting the target value based on the change value input from the selection means; A toner concentration control device for an electrophotographic apparatus, comprising: a control means for adjusting toner concentration so that the input calculated value maintains the correction value input from the calculation means.