JPH0651602A - Process controller - Google Patents

Abstract

PURPOSE:To prevent a situation that image forming processing is not executed in an image forming performable state or image quality is remarkably deteriorated by providing 1st and 2nd control means which are specified. CONSTITUTION:When process control must be executed, the temperature To of a developing device is detected(n3). In the case the temperature T of the developing device is equal to or under an inflection point TS(45 deg.C), a test patch is formed in both a dark pattern and a light pattern, and output from an electrostatic charging device, output from the developing device, output from an exposure device, and output from a destaticizing device are controlled(n3 n4 n5). The formations of the test patch in the dark pattern and the light pattern formed three times. Meanwhile, the temperature T of the developing device exceeds the point TS, there is possibility that the output control of the electrostatic charging device exceeds a control range, so that the control of the dark pattern is not performed but only the control of the light pattern is executed(n3 n5), a timer is started(n6), and the image forming processing is started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process control device for stabilizing image quality in an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, it is possible to prevent the image quality from being deteriorated (the image quality is not stable) due to changes in the photosensitive member, charging device, exposure device, developing device, etc. over time and environmental changes. In order to prevent this, the output of the charging device, the exposure device, the developing device, etc. is adjusted at regular intervals (for example, when the power of the image forming apparatus is turned on, and every predetermined time while the power is on). In this adjustment, a preset charging device output, exposure device output, developing device output, etc. are set to form a test patch (toner image), and the charging device output and exposure are set according to the toner density of the test patch. The output of the device, the output of the developing device, etc. are adjusted. Generally, the test patch is formed in two patterns. One is a dark portion pattern, in which a photoconductor is charged by a charging device and toner is directly attached onto the photoconductor. The other is the light pattern, which cancels the charge on the surface of the photoconductor by distributing the reflected light from the test plate to the photoconductor charged by the charging device using the above-mentioned exposure device, so that the remaining charge remains. The toner is attached. When testing the dark area pattern, if the toner density is lower than the specified density, increase the output of the charging device or decrease the output of the developing device (increase the potential difference from the surface of the photoconductor) to make the toner density lower than the specified density. When it is high, the opposite control is performed. In addition, when testing the light pattern, the output of the charging device is adjusted by combining it with the test result of the dark pattern, and the output of the exposure device is increased when the toner concentration is high, and when the toner concentration is low, the light amount is increased. Adjust to lower. Such adjustment is called process control.

[0003]

When the above process control is performed, the output after adjustment, which is calculated, may exceed the controllable range. In particular, in the output control of the charging device, there is a possibility that the capacity of the charging transformer is insufficient, or the output is increased too much to cause problems such as charger leak.

Therefore, if the conventional apparatus exceeds the controllable range, it is judged as a trouble and the operation of the image forming apparatus itself is stopped, or the output of the charging device, the output of the exposure device, the output of the developing device, etc. Either the image forming process is continued in the state where the above control is not performed at all. Therefore, there is a problem that the image forming process cannot be performed even though the image can be formed, or the image quality is significantly deteriorated.

In view of the above problems of the present invention, there is provided a process control device which prevents the image forming process from being disabled even when the image forming is possible and the image quality from being significantly deteriorated. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION According to the present invention, in an image forming apparatus having a charging device, an exposing device, a developing device and a discharging device around a photoconductor, the surface of the photoconductor is charged by the charging device and then the developing device is used. First control means for adhering toner to the charged electric charge on the surface of the photoconductor and controlling the output of the charging device, the output of the developing device, and the output of the neutralization device according to the amount of the adhered toner; and the surface of the photoconductor by the charging device. Is exposed to light by the exposure device, toner is further attached to the charge on the surface of the photoconductor by the developing device, and the output of the exposure device is determined according to the amount of the attached toner.
Second control means for controlling the output of the developing device, temperature detecting means for detecting the temperature of the developing device portion, and when the temperature detected by the temperature detecting means is below a predetermined temperature, the first control means and the first controlling means. It is characterized in that it comprises: a means for executing the second control means; and a means for executing only the second control means when the temperature detected by the temperature detection means exceeds a predetermined temperature.

[0007]

When the temperature of the developing device section becomes higher than the predetermined temperature, the charge amount of the toner changes. For example, as shown in FIG. 3, when the temperature exceeds a predetermined temperature (45 ° C.), the charge amount of the toner rapidly increases. When image formation (toner control) is performed using such a toner having a high charge amount, the image density becomes low as shown in FIG. In this case, if the normal toner control (both the first control means and the second control means) is performed, the capacity of the charging transformer becomes insufficient especially in the output control of the charging device, or the output becomes too high and the charger leaks. May cause the problem of.

In the present invention, when the temperature of the developing device exceeds a predetermined temperature, the process control control including the control of the charging device is not performed (the first control means is not performed), and the above problem does not occur. However, the second control means performs and controls the output of the exposure device, the output of the developing device, and the like.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 4 is a diagram showing the construction of the main parts of an electrophotographic image forming apparatus.

The photoconductor 1 having photoconductivity is formed in a drum shape and is rotatably supported. A main motor (not shown) is connected to the rotation shaft of the photoconductor 1 to transmit the driving force. Around the photoconductor 1, a charging device 2, a blank lamp 3, a developing device 4, a pre-transfer charge eliminating device 5, a pre-transfer charge eliminating lamp 6, a transfer device 7, a peeling device 8, a toner concentration sensor 9, a cleaner unit 10, a charge eliminating device. Lamp 11, PFL / CFL
12 are arranged in this order.

The image forming process is executed as follows. A voltage is applied to the charging device 2 and the charging device 2 causes a corona discharge to generate a single-polarity potential on the surface of the photoconductor 1. The blank lamp 3 exposes the non-image area on the surface of the photoconductor 1 to cancel the charge in the non-image area. Next, image forming light such as document reflection light and laser light is distributed to the image area on the surface of the photoconductor 1 to form an electrostatic latent image. To the electrostatic latent image, toner having a polarity opposite to the surface charge of the surface of the photoconductor 1 is supplied from the developing device 4, and the electrostatic latent image is visualized (a toner image is formed). Next, the toner image faces the pre-transfer charge eliminating device 5. The pre-transfer charge eliminating device 5 performs a corona discharge having a polarity opposite to that of the charging device, that is, the same polarity as that of the toner to increase the charge amount of the toner, thereby facilitating the transfer process. The pre-transfer charge eliminating lamp 6 exposes the surface of the photoconductor 1 to cancel the residual charge on the surface of the photoconductor to facilitate the transfer of toner. After that, the toner image faces the transfer device 7. The transfer device 7 generates a corona discharge having a polarity opposite to that of the toner, and transfers the toner image onto the paper fed from a paper feed unit (not shown). The peeling device 8 performs AC corona discharge on the paper on which the toner image is transferred, and reduces the adhesion of the paper to the surface of the photoconductor 1 to assist the peeling of the paper. This sheet is peeled from the photoconductor 1 and then conveyed to a fixing device (not shown) for fixing processing. On the other hand, in the photoconductor 1, the cleaner unit 10 removes the toner remaining on the photoconductor surface, and the charge removal lamp 11 and the PFL / CFL 12 remove the surface charge.

The developing device 4 is provided with a magnet roller 4b and a stirring roller 4c inside a developing tank 4a. A two-component developer including toner and carrier is stored in the developing tank 4a. The two-component developer is agitated by the agitating roller 4c, so that the two-component developer is rubbed with each other and charged with opposite polarities. The charge amount of the toner (carrier) at this time is related to the ambient temperature (temperature of the developing device section). FIG. 3 is a diagram showing the relationship. As can be seen from the figure, the charge amount (Q / M) of the developer sharply increases with a certain temperature as an inflection point. This inflection point is about 45 ° C. although it depends on the type of the two-component developer. In this case, when the temperature of the developing device section exceeds 45 ° C., the toner charge amount sharply increases. A temperature detecting sensor for detecting the inflection point is provided inside or around the developing device 4.

FIG. 2 is a diagram showing the relationship between the charge amount of the toner and the density of the toner image formed. As can be seen from the figure, the density of the toner image formed on the photoconductor 1 decreases as the charge amount of the toner increases. It is considered that this is because each toner (powder having a particle size of about 10 μm) has a large amount of charge, and a small amount of toner balances with the surface charge of the photoconductor 1. Generally, when the toner density of a test patch decreases, the process control device adjusts the output of the charging device to increase the surface potential of the photoconductor, and adjusts the output of the developing device to adjust the surface potential of the photoconductor and the magnet roller. The toner concentration is controlled so as to be kept constant by increasing the potential difference from the potential. However, if the charge amount of the toner is significantly increased due to the temperature change as described above, the output of the charging device or the output of the developing device in calculation may exceed the control range. In particular, this problem is likely to occur when forming a test patch having a dark pattern. This is because in the case of a test patch having a dark pattern, the amount of charge on the surface of the photoconductor is large and the difference in the amount of toner attached is large. Therefore, the dark pattern is not tested when there is a possibility that the charge amount of the toner may change due to the temperature change. FIG. 1 is a flowchart showing the processing procedure. FIG. 1 (A) is a main flow, FIG. 1 (B) is a dark part pattern test flow (first control means flow), and FIG. 1 (C) is clear. The test flow (flow of a 2nd control means) of a partial pattern is shown.

When the print switch is operated, the timer time is determined (n1 → n2). This timer is started when the previous process control is finished, and in this embodiment, it measures one hour. That is, the process control is performed at the time of the first image forming processing after 1 hour has passed since the process control was performed previously. When it is necessary to perform process control, the temperature T of the developing device is first detected (n3). The temperature T of the developing device 4 is the inflection point TS (45 ° C.)
In the following cases, test patches are formed with both the dark pattern and the light pattern, and the output of the charging device, the output of the developing device,
Controls the output of the exposure device and the output of the static eliminator (n3 →
n4 → n5). The formation of test patches for the dark pattern and the light pattern is performed three times each (FIG. 1 (B),
(C)). On the other hand, if the temperature T of the developing device 4 exceeds the inflection point TS, the output control of the charging device may exceed the controllable range. Therefore, the dark part pattern is not controlled and only the light part pattern is controlled. Is performed (n3 → n5). When the above process control is completed, the timer is started (n6) and the image forming process is started.

In this embodiment, the process control is performed when the print switch is operated, but it may be performed at another timing. For example, it may be performed during warm-up when the power of the image forming apparatus is turned on. The output of the static eliminator may also be controlled.

[0016]

According to the present invention, the process control control including the control of the charging device is not performed when the temperature of the developing device exceeds the predetermined temperature and the output control of the charging device is likely to exceed the controllable state. Since the first control means is not performed, there is no problem that the transformer capacity of the charging device is insufficient or the output is increased too much to cause a charger leak. However, even when the first control means is not executed, the second control means is executed,
Since the output of the exposure device and the output of the developing device are adjusted, the image quality does not deteriorate significantly.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing procedure of process control.

FIG. 2 is a diagram showing a relationship between a toner charge amount and a toner image density.

FIG. 3 is a diagram showing the relationship between the temperature of the developing device and the toner charge amount.

FIG. 4 is a diagram showing a main configuration of an image forming apparatus.

Claims (1)

[Claims] 1. An image forming apparatus comprising a charging device, an exposing device, a developing device, and a destaticizing device around a photoconductor, wherein the charging device charges the surface of the photoconductor and then the developing device charges the surface of the photoconductor. Attach toner,
First control means for controlling the output of the charging device, the output of the developing device, and the output of the static eliminator in accordance with the amount of adhered toner; and the exposure device performing exposure after charging the surface of the photoconductor by the charging device, Further, the developing device causes toner to adhere to the charged charges on the surface of the photoconductor, and second control means for controlling the output of the exposure device and the output of the developing device according to the amount of the adhered toner, and the temperature of the developing device section are detected. And a temperature detecting means for executing the first control means and the second control means when the temperature detected by the temperature detecting means is equal to or lower than a predetermined temperature, and a temperature detected by the temperature detecting means is a predetermined temperature. And a means for executing only the second control means when the temperature exceeds the above.