JPH05241403A - Image quality stabilizing device for electrophotographic device - Google Patents

Abstract

PURPOSE:To obtain stable image quality even when transfer efficiency is changed by correcting a reference value based on detected value by an optical detection means for detecting toner adhesive amount on a photosensitive body after transferring a reference toner image. CONSTITUTION:The toner adhesive amount on the photosensitive body 1 after transfer is detected by the optical detection means 9. Based on the detected value, the reference value is corrected by a reference value correcting means. When the brightness of the formed image transferred becomes low because the transfer efficiency is lowered by repeating image formation, the toner adhesive amount after transfer becomes large. In such a case, the reference value is corrected so that the toner amount of the reference toner image may be increased. On the contrary, when the toner adhesive amount after transfer is small, the reference value is corrected in a reverse manner. Since process control where image quality stabilizing accuracy is improved is executed based on the reference value corrected according to the toner adhesive amount on the photosensitive body after transfer, the image quality is appropriately corrected even when the transfer efficiency is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image quality stabilizing device for an electrophotographic apparatus, which is capable of obtaining a stable formed image by controlling each part of the electrophotographic process based on the density of a reference toner image. ..

[0002]

2. Description of the Related Art In an electrophotographic apparatus such as a copying machine or a laser printer, the surface potential of a photoreceptor greatly changes due to changes in environment. Further, the photosensitive member tends to cause film slippage and decrease in the film thickness of the photosensitive layer due to accumulation of mechanical stress such as polishing with a cleaning blade as image formation is repeated, and the surface potential gradually decreases. there were. When such a change in the surface potential occurs, the image quality of the formed image is greatly affected by a decrease in density.

On the other hand, for example, Japanese Examined Patent Publication No. 61-295.
In the apparatus according to the publication No. 02, the image quality is stabilized by reading the electrostatic latent image formed on the photoconductor and controlling the formation of the electrostatic latent image according to the result. In addition, other than this, there is a device that includes a means for detecting the optical density of the toner image on the photoconductor and employs a method of controlling the electrophotographic process so as to obtain the optimum image quality according to the detection result. is there.

[0004]

However, in a copying machine or the like, image quality correction is performed only by process control from charging and exposure to development, and transfer efficiency due to deterioration of developer or environmental change Even the control for the change of was not considered. For this reason, even though the image quality is corrected, the image quality becomes unstable due to the change in transfer efficiency as described above.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to obtain a stable image quality even when the transfer efficiency is changed, by adding the transfer efficiency as one element of the image quality correction. There is.

[0006]

An image stabilizing device for an electrophotographic apparatus according to the present invention has an optical detecting means for optically detecting a toner amount of a reference toner image formed on a photoconductor, and a detection value thereof. In order to solve the above-mentioned problems, in an image quality stabilizing device of an electrophotographic apparatus for stabilizing the image quality of a formed image by controlling each part of the electrophotographic process so that the value becomes a preset reference value, It is characterized in that it is provided with a reference toner image transfer means for transferring the reference toner image formed after the control onto the transfer paper, and with different means for each of the following claims.

According to a first aspect of the present invention, there is provided an image quality stabilizing device for an electrophotographic apparatus, which comprises a reference value correcting means for correcting the reference value based on the detection value of the toner adhesion amount on the photoconductor after the transfer of the reference toner image by the optical detecting means. Is equipped with.

In the image quality stabilizing device of the electrophotographic apparatus according to any one of claims 2 to 7, the detection value of the toner adhesion amount on the photosensitive member after the transfer of the reference toner image by the optical detecting means is a remaining amount reference. It is provided with a means for controlling each of the following controlled variables so that the value becomes a value.

That is, in the image quality stabilizing device of the electrophotographic apparatus according to the second and third aspects, the above means is a transfer output control means for controlling the transfer output. The image quality stabilizing device for an electrophotographic apparatus according to the third aspect includes a peeling output control unit that controls the peeling output according to the transfer output controlled by the transfer output controlling unit.

In the image quality stabilizing device for an electrophotographic apparatus according to any one of claims 4 to 7, each of the above means is a charging output control means for controlling the charging output, and controls the output of the static elimination performed immediately before the transfer. It is a pre-transfer charge eliminating output control means, a pre-transfer charge eliminating light quantity control means for controlling the light quantity of the light charge eliminating immediately before the transfer, and a developer supply amount control means for controlling the developer supply amount.

[0011]

In the image quality stabilizing device for an electrophotographic apparatus according to each of the above claims (hereinafter, appropriately referred to as image quality stabilizing device), the toner amount of the reference toner image detected by the optical detecting means becomes the reference value. After each part of the electrophotographic process is controlled, the reference toner image formed again on the photoconductor is transferred to the transfer paper by the reference toner image transfer means.

Next, in the image quality stabilizing apparatus according to the first aspect, the toner adhesion amount on the photoconductor after transfer is detected by the optical detecting means, and the reference value correcting means determines the reference value based on the detected value. Will be corrected. When the transfer efficiency decreases due to the repeated image formation and the density of the transferred formed image becomes low, the toner adhesion amount after the transfer increases, but
In this case, the reference value is corrected so that the amount of toner in the reference toner image increases. On the contrary, when the toner adhesion amount after transfer is small, the reference value is corrected contrary to the above case.

As described above, according to the image quality stabilizing device of the first aspect, the process control is performed based on the reference value corrected by the toner adhesion amount on the photoconductor after the transfer. Even if the efficiency changes, the image quality can be appropriately corrected, and a stable formed image can always be obtained.

In the image quality stabilizing device according to any one of claims 2 to 7, when the amount of toner adhered to the photoconductor is detected by the optical detecting means after the transfer, the detected value becomes a preset remaining amount reference value. As described above, each controlled variable is controlled.

In the image quality stabilizing device according to the second aspect, the transfer output is controlled by the transfer output control means. For example, when the amount of toner adhered to the photoconductor is large, the transfer output is increased so that the amount of toner transferred to the transfer paper is large, and when the amount is large, the transfer output is decreased. Further, in the image quality stabilizing device according to the third aspect, since the peeling output control unit controls the peeling output according to the transfer output, the peeling can be performed in an optimum state, and the peeling failure of the transfer paper or the toner can be prevented. Image transfer failure does not occur.

In the image quality stabilizing apparatus according to any one of claims 4 to 7, the charge output is controlled by the charge output control means so that the detected value of the toner adhesion amount on the photoconductor after the transfer becomes the remaining amount reference value. The output of the charge removal performed immediately before the transfer is controlled by the pre-transfer charge removal output control means.
The pre-transfer charge removal light amount control unit controls the light amount of the light charge removal performed immediately before the transfer, thereby controlling the supply amount of the developer.
This control is performed, for example, by obtaining a correction amount of each controlled amount with respect to a difference between the detected value of the toner adhesion amount and the reference amount of the remaining amount or a change of the transfer efficiency, and based on the correction amount.

As described above, the above claims 2 to 7
According to the image quality stabilizing device of the present invention, since each controlled amount is controlled with the remaining amount reference value as a target, the image quality can be properly corrected even if the transfer efficiency changes, and a stable formed image is always obtained. Obtainable.

[0018]

【Example】

[Embodiment 1] The following description will discuss Embodiment 1 of the present invention with reference to FIGS. 1 to 3.

As shown in FIG. 2, the electrophotographic apparatus according to this embodiment includes a cylindrical photosensitive drum 1 which is a photosensitive member. The photoconductor drum 1 is rotatably provided in the apparatus in the A direction, and an electrostatic latent image is formed by exposing a document image with light emitted from the B direction. ..

A scorotron-type charger 2 for charging the photosensitive drum 1 is arranged near the uppermost end of the photosensitive drum 1. The charger 2 has a grid electrode 2a, and the charging output is controlled by controlling the grid voltage applied to the grid electrode 2a.

Around the photosensitive drum 1, a blank lamp 3, a developing device 4, a pre-transfer charge eliminator 5, a pre-transfer charge eliminator 6, a transfer device 7, a peeling device 8, an optical sensor 9, and a cleaner unit 10 are also provided. A static elimination lamp 11 and a light fatigue imparting lamp 12 are arranged.

The blank lamp 3 irradiates the non-image area of the photosensitive drum 1 which does not face the document, and is composed of an LED.

The developing device 4 has a stirring roller 4a and a magnet roller 4b therein. Stirring roller 4a
Is configured to agitate the two-component developer to triboelectrically charge the toner and the carrier. Magnet roller 4a
Has a cylindrical non-magnetic sleeve forming an outer peripheral portion and a magnetic pole inside thereof, and the sleeve is provided so as to be rotated by the rotational driving force transmitted by the clutch 4c. This magnet roller 4a
Is configured to adhere the developer to the sleeve by the magnetic force of the magnetic pole to form a magnetic brush, and the sleeve is rotated to supply the developer to the photosensitive drum 1.

The pre-transfer static eliminator 5 transfers corona discharge having a polarity opposite to that of the charger 2 and the same polarity as the toner before transferring the toner attracted to the electrostatic latent image by the developing device 4 to the transfer paper. Is applied to cancel the electric charge to weaken the attraction force of the toner to the photosensitive drum 1. The pre-transfer charge erasing lamp 6 further cancels the charge of the electrostatic latent image by light erasing to weaken the attraction of the toner to the photosensitive drum 1.

The transfer device 7 transfers the toner image on the photosensitive drum 1 to the transfer paper by subjecting the transfer paper to corona discharge having the same polarity as that of the charger 2. The peeling device 8 applies AC corona discharge to the transfer paper on which the toner image has been transferred to relax the attraction force of the toner to the photoconductor drum 1 and separate the transfer paper from the photoconductor drum 1. Is becoming

In the image forming step after peeling, the transfer paper on which the toner image is transferred is conveyed to a fixing device (not shown), and the fixing device heats and pressurizes the transfer paper to melt and fix the toner image on the transfer paper. It has become so.

The optical sensor 9 is composed of a light emitting diode 9a and a phototransistor 9b. The optical sensor 9 receives the light emitted from the light emitting diode 9a and reflected by the photoconductor drum 1 by the phototransistor 9b, detects the amount of the light as the amount of toner adhering to the photoconductor drum 1, and detects the detected value. It is designed to output as an electric signal.

The cleaner unit 10 includes a blade 10
The blade 10a scrapes off and collects the toner adhering to the photosensitive drum 1 by the blade 10a, thereby removing the toner adhering to the surface of the photosensitive drum 1.

The static elimination lamp 11 erases the potential remaining on the photosensitive drum 1 by irradiating the photosensitive drum 1 with light. Light fatigue imparting lamp 12
Irradiates the photoconductor drum 1 with light different from that of the static elimination lamp 11 to erase the potential which could not be completely eliminated by the static elimination lamp 11, and gives a constant light fatigue so that the image density is increased at each image formation. It is designed to prevent fluctuations.

The electrophotographic apparatus, as shown in FIG. 1, includes a process control section 13. This process control unit 1
Reference numeral 3 denotes an optical sensor 9 as an optical detecting means and, for example, R
A process control program 14 stored in the OM,
A memory 15 that stores the detection output of the optical sensor 9 and the like, and a CPU 16 that controls each part of an electrophotographic process (hereinafter, simply referred to as a process) according to a process control program 14 are provided.

At the beginning of image formation, the CPU 16
Detection output of the optical sensor 9 that reads the toner patch as the reference toner image (hereinafter, referred to as pre-transfer sensor output)
Is stored in the memory 15 in advance as a reference value, the toner patch is transferred onto the transfer paper, and the output of the optical sensor 9 indicating the toner adhesion amount on the photosensitive drum 1 at that time (hereinafter, referred to as post-transfer sensor output). ) As the reference value for the remaining amount
It is designed to be stored in 5. In addition, the CPU 16
Is a fixed number of image formations, in image quality stabilization control,
Image stabilization is performed by controlling each process part so that the pre-transfer sensor output obtained from the toner patch becomes the above-mentioned reference value, and after this process is completed, the toner patch created again is transferred to the transfer paper. A correction value for the reference value is calculated by performing a predetermined calculation based on the ratio between the post-transfer sensor output and the remaining amount reference value and the reference value.

In this way, the process control unit 13
By executing the process control program 14 by U16, it has a function as a reference toner image transfer means and a reference value correction means.

The operation of the process control for stabilizing the image quality in the above configuration will be described.

First, when the toner patch is formed on the photosensitive drum 1, the pre-transfer sensor output obtained by the optical sensor 9 at that time is stored in the memory 15 as the reference value T ₁ . Next, when the toner patch is transferred to the transfer paper, the post-transfer sensor output obtained by the optical sensor 9 becomes
The remaining amount reference value S ₁ is stored in the memory 15.

Thereafter, a toner patch is formed every time a fixed number of images are formed, and the pre-transfer sensor output obtained at that time is compared with the reference value T ₁ . Based on the result of this comparison, the controlled amount, the exposure amount, the charging output, the developing bias voltage and the like of each process portion are obtained so that the pre-transfer sensor output becomes the reference value T ₁ , and the process control is performed based on these.

After the above control, the toner patch is transferred onto the transfer paper, and the post-transfer sensor output obtained at that time is stored in the memory 15 as the remaining amount comparison value S ₂ . Then, the correction reference value T ₂ used for the process control is obtained by the calculation by the following equation. T ₂ = T ₁ × S ₂ / S ₁ Then, the reference value T ₁ is updated to the correction reference value T ₂ obtained as described above, and thereafter, the process control is performed based on this correction reference value T _2. Then, the density of the toner patch is corrected.

By the way, in the electrophotographic apparatus, in the process control without considering the transfer efficiency, when there is no change in the environment, as shown by the solid line in FIG. The image density is stable and the image density tends to decrease due to a change in transfer efficiency as image formation is repeated. On the other hand, in the process control of the electrophotographic apparatus, the reference value of the pre-transfer sensor output is corrected based on the post-transfer sensor output obtained after the toner patch density correction, so that the change in the developer may cause Even if the transfer efficiency changes, the decrease in image density can be suppressed as shown by the broken line in the figure.

[Second Embodiment] The second embodiment of the present invention will be described below with reference to FIGS. 2 and 4 to 6.

As shown in FIG. 1, the electrophotographic apparatus according to the present embodiment is provided with a process section formed by the photosensitive drum 1 and the transfer unit 7 and the like arranged around the photosensitive drum 1.

Further, the electrophotographic apparatus is provided with a process control section 17 as shown in FIG. The process control unit 17 has an optical sensor 9, a process control program 18, a memory 15, and a CPU 16.

The CPU 16 stores the ratio of the pre-transfer sensor output and the post-transfer sensor output obtained in the initial stage of image formation in the memory 15 as the reference transfer efficiency, and similarly obtains the same when performing the image quality stabilizing process. The output of the transfer device 7 is controlled so that the transfer efficiency becomes the above-mentioned reference transfer efficiency. As described above, the process control unit 17 includes the CPU 1
6 executes the process control program 18 to have a function as a transfer output control unit, and
It has a function as a reference toner transfer means.

Here, the relationship between transfer efficiency and transfer output will be described.

At the time of transfer, as shown in FIG. 5, the toner T attached to the charges Q ₁ forming an electrostatic latent image on the photosensitive drum 1 is transferred to the back surface of the transfer paper P by corona discharge of the transfer device 7. charge Q ₁ ... the same polarity generated in the charge by Q ₂ ..., are attracted to the transfer sheet P.

In such transfer, with the normal transfer characteristic shown by the broken line in FIG. 6, when the transfer output is low, the transfer paper P
Since the amount of charge on the back surface is small, the toner T on the photosensitive drum 1
However, when the transfer output increases, the amount of charge on the back surface of the transfer paper P increases and the suction force of the toner increases, so that more of the toner T is drawn to the transfer paper P. Further, when the transfer output is increased, the electric charge on the back surface of the transfer paper P is excessively increased and dielectric breakdown occurs between the front surface and the back surface of the transfer paper P, and the electric charge Q ₂ on the back surface of the transfer paper P moves to the surface of the photosensitive drum 1. Therefore, the transfer efficiency is reduced. The maximum value of transfer efficiency is about 85% at present.

In this electrophotographic apparatus, a look-up table is created by associating the amount of decrease in transfer efficiency with the amount of correction of transfer output, and the correction amount obtained from this look-up table is shown by the solid line in FIG. As described above, the transfer output is changed according to the change in the transfer efficiency to compensate for the decrease in the transfer efficiency.

The operation of the process control for stabilizing the image quality in the above configuration will be described.

First, when a toner patch is formed on the photosensitive drum 1, the pre-transfer sensor output obtained by the optical sensor 9 is stored in the memory 15. Then, the toner patch is transferred onto the transfer paper, and the post-transfer sensor output obtained by the optical sensor 9 is stored in the memory 15. At this time, the transfer efficiency determined by the sensor output before and after the transfer is stored in the memory 15 as the reference transfer efficiency. After that, a toner patch is formed every time a certain number of images are formed, and the output of the transfer device 7 is controlled so that the transfer efficiency obtained in the same manner as above becomes the reference transfer efficiency, and the transfer efficiency is improved. Will be corrected.

As described above, in the electrophotographic apparatus according to the present embodiment, the transfer output is controlled according to the decrease in the transfer efficiency, so that the transfer efficiency changes due to the change of the developer. Also, it is possible to suppress a decrease in image density.

[Third Embodiment] A third embodiment of the present invention will be described with reference to FIGS. 2, 5, and 7 to 9.
It is as follows.

As shown in FIG. 2, the electrophotographic apparatus according to the present embodiment is provided with a process section formed by the photosensitive drum 1, the transfer unit 7 and the peeling unit 8 arranged around the photosensitive drum 1. There is. The electrophotographic apparatus also includes a process control unit 19 as shown in FIG. 7. The process control unit 19 has an optical sensor 9, a process control program 20, a memory 15, and a CPU 16.

The CPU 16 controls the output of the transfer device 7 as in the electrophotographic apparatus of the second embodiment. Further, when the image quality stabilizing process is performed, the CPU 16 corrects the peeling output by using a look-up table created by associating the corrected transfer efficiency with the optimum output of the peeling device 7. .. As described above, the process control unit 19 has the functions of the transfer output control unit and the peeling output control unit and the function of the reference toner image transfer unit by the CPU 16 executing the process control program 20. Is becoming

Here, the relationship between the transfer efficiency and the peeling output will be described.

At the time of peeling, as shown in FIG. 5, when the extra charge Q ₂ on the back surface of the transfer paper P is canceled by the AC corona discharge of the peeling device 8 after the transfer, it acts between the transfer paper P and the photosensitive drum 1. The Coulomb force to be weakened is weakened, and the transfer paper P is separated from the photosensitive drum 1 due to its rigidity and its own weight.

FIG. 8 shows a change in the adhesion force between the photosensitive drum 1 and the transfer paper P (hereinafter referred to as the drum / transfer paper adhesion force) with respect to the transfer output. In this figure, in the range where the transfer output is low, the adhesion force between the drum and the transfer paper increases as the transfer output increases, but when the transfer output exceeds a certain value,
An abnormal charging voltage of the transfer paper P occurs, and a charge Q ₂ ... Leaks from the back surface of the transfer paper P to the photosensitive drum 1, and the adhesion between the drum and the transfer paper is saturated. On the other hand, if the transfer output is too low, the adhesion between the transfer paper P and the toner T ...
Transfer failure of the toner T ... Occurs. Therefore, in order to peel off the transfer paper P without causing the transfer failure of the toner T ..., It is necessary to set the drum / transfer paper adhesive force to around R.

In this electrophotographic apparatus, in order to maintain the adhesion force between the drum and the transfer paper near R, as shown in FIG. 9, the peeling output is controlled so that the transfer output and the peeling output have a proportional relationship. It has become.

In the above structure, when the image quality stabilizing process is performed, the output of the transfer device 7 is controlled by the transfer efficiency obtained by the sensor output before and after the transfer, as in the second embodiment. At this time, the output of the peeling device 8 is also controlled according to the change of the transfer output. In this way, the transfer efficiency is corrected by controlling the outputs of the transfer device 7 and the peeling device 8.

As described above, in the electrophotographic apparatus according to this embodiment, the transfer output and the peeling output are controlled according to the decrease in the transfer efficiency. Even if it changes, it is possible to suppress a decrease in image density, and it is possible to perform excellent peeling without impairing transfer.

[Embodiment 4] The following description will discuss Embodiment 4 of the present invention with reference to FIGS. 2 and 10 to 12.

As shown in FIG. 1, the electrophotographic apparatus according to the present embodiment is provided with a process section formed by a photosensitive drum 1 and a charger 2 arranged around the photosensitive drum 1.
Further, the electrophotographic apparatus includes a process control unit 21 as shown in FIG. This process control unit 21
Is an optical sensor 9, a process control program 22,
It has a memory 15 and a CPU 16.

The CPU 16 stores the post-transfer sensor output in the initial stage of image formation as the remaining amount reference value in the memory 15, and calculates the difference between the post-transfer sensor output and the remaining amount reference value when performing the image quality stabilizing process. Then, the correction amount of the charging output according to this difference is obtained from the relationship between the change in the post-transfer sensor output and the change in the charging output, and the grid voltage of the charger 7 is controlled by the correction amount. As described above, the process control unit 21 has the function as the charging output control unit and the function as the reference toner image transfer unit when the CPU 16 executes the process control program 22.

Now, the relationship between the post-transfer sensor output and the charging output will be described.

FIG. 11 shows the relationship between the post-transfer sensor output and the image density of the formed image, which has a characteristic that the post-transfer sensor output gradually increases in a curve as the image density increases. In this figure, when the sensor output after transfer decreases from S to S ′, that is, when the amount of remaining toner on the photosensitive drum 1 after transfer increases, the image density also decreases from D to D ′ accordingly.

On the other hand, FIG. 12 shows the relationship between the charging output and the image density of the formed image. The charging output has a characteristic that it changes linearly below a certain value. In this figure, the charging output changes from E to E'as the image density changes from D to D '. Therefore, the charging output is changed from E to E ′ with respect to the decrease of the sensor output after transfer from S to S ′.
By increasing only the change amount to, the decrease amount of the image density from D to D'is corrected.

In this electrophotographic apparatus, a look-up table in which the change in the sensor output after transfer and the correction amount of the charging output are associated with each other based on the above relationship is created, and the charging amount is calculated by the correction amount obtained from this look-up table. The discharge output of the container 7 is changed to compensate for the decrease in transfer efficiency.

The operation of the process control for stabilizing the image quality in the above configuration will be described.

First, when a toner patch is formed on the photosensitive drum 1 after the pre-transfer sensor output (reference value) is corrected by the toner patch, this toner patch is transferred to the transfer paper. Then, the post-transfer sensor output obtained by the optical sensor 9 is stored in the memory 15 as the remaining amount comparison value,
The difference between the remaining amount comparison value and the previously stored remaining amount reference value is calculated, and the correction amount of the charging output according to the difference is obtained.
Then, the grid voltage applied to the charger 2 is controlled by this correction amount, and the toner adhesion amount on the photosensitive drum 1 after transfer is corrected.

As described above, in the electrophotographic apparatus according to the present embodiment, the charging output is controlled according to the change in the post-transfer sensor output, so that the transfer efficiency changes due to the change of the developer or the like. Even in this case, it is possible to suppress a decrease in image density.

[Embodiment 5] The following description will discuss Embodiment 5 of the present invention with reference to FIGS. 2, 11, 13, and 14.

As shown in FIG. 1, the electrophotographic apparatus according to this embodiment includes a process section formed by the photosensitive drum 1 and the pre-transfer charge eliminator 5 and the like arranged around the photosensitive drum 1. The electrophotographic apparatus, as shown in FIG.
The process control unit 23 is provided. The process control unit 23 includes an optical sensor 9 and a process control program 24.
And a memory 15 and a CPU 16.

The CPU 16 stores the post-transfer sensor output in the initial stage of image formation in the memory 15 as the remaining amount reference value, and also predicts the remaining amount reference value and the expected value of the post-transfer sensor output when performing the image quality stabilizing process in advance. The change rate of the sensor output after transfer is obtained from the (experimental value), and an appropriate charge removal output before transfer corresponding to this change rate is set. Further, when performing the image quality stabilizing process, the CPU 16 obtains the change rate of the post-transfer sensor output from the actual post-transfer sensor output and the remaining amount reference value, and obtains the change rate based on the above setting. The total current of the pre-transfer static eliminator 5 is controlled by the pre-transfer static eliminator output. in this way,
When the CPU 16 executes the process control program 24, the process control unit 23 has a function as a pre-transfer charge eliminating output control unit and a function as a reference toner image transfer unit.

Here, the relationship between the change rate of the post-transfer sensor output and the pre-transfer charge eliminating output will be described.

If the change rate of the image density is obtained as the change rate S '/ S of the post-transfer sensor from the characteristics shown in FIG. 11, in order to keep the toner adhesion amount after transfer to the photosensitive drum 1 constant,
As shown in FIG. 14, as S ′ is closer to S, the toner remaining amount on the photosensitive drum 1 is smaller. Therefore, the charge removal output before transfer is lowered, and as the post-transfer sensor output S ′ is smaller than S, the toner remaining amount is Since the amount is large, it is necessary to increase the pre-transfer charge removal output.

In the present electrophotographic apparatus, a look-up table in which the rate of change in the post-transfer sensor output and the pre-transfer static elimination output are associated with each other is created, and the pre-transfer static elimination output obtained from this look-up table is created. Thus, the discharge output of the pre-transfer charge eliminator 5 is controlled to compensate for the decrease in transfer efficiency.

The operation of the process control for stabilizing the image quality in the above configuration will be described.

First, when a toner patch is formed on the photosensitive drum 1 after the pre-transfer sensor output is corrected by the toner patch, this toner patch is transferred to the transfer paper.
Then, the post-transfer sensor output S ′ is obtained by the optical sensor 9, and the change rate S ′ / S of the post-transfer sensor output is calculated from the post-transfer sensor output S ′. From this change rate S ′ / S, the pre-transfer charge eliminating output is obtained from the above relationship, and the discharge output of the pre-transfer charge eliminating device 5 is controlled based on this, so that the toner adhesion amount on the photosensitive drum 1 after the transfer is controlled. Will be corrected.

As described above, in the electrophotographic apparatus according to the present embodiment, the pre-transfer charge eliminating output is controlled according to the post-transfer sensor output, so that the transfer efficiency changes due to the change of the developer or the like. Even in this case, it is possible to suppress a decrease in image density.

[Sixth Embodiment] The sixth embodiment of the present invention will be described below with reference to FIGS. 2 and 15 to 17.

As shown in FIG. 1, the electrophotographic apparatus according to this embodiment includes a process section formed by the photosensitive drum 1 and a pre-transfer charge eliminating lamp 6 and the like arranged around the photosensitive drum 1. The electrophotographic apparatus also includes a process control unit 25, as shown in FIG. The process control unit 25 has an optical sensor 9, a process control program 26, a memory 15, and a CPU 16.

The CPU 16 stores the ratio of the output of the optical sensor 9 before and after the transfer in the initial stage of image formation in the memory 15 as the reference transfer efficiency, and the transfer efficiency when performing the image quality stabilizing process becomes the reference transfer efficiency. In this way, the light quantity of the pre-transfer charge eliminating lamp 6 (hereinafter referred to as PTL light quantity) is controlled. In this way, the process control unit 25
When the PU 16 executes the process control program 26, the PU 16 has a function as a pre-transfer charge removal light amount control unit and a function as a reference toner image transfer unit.

The relationship between the transfer efficiency and the PTL light amount will be described.

As shown in FIG. 16, the pre-transfer charge eliminating lamp 6 irradiates the photosensitive drum 1 with light to cancel the charges Q ₁ ... Forming the electrostatic latent image. Therefore, the adhesion of the toner T to the photosensitive drum 1 due to the Coulomb force is weakened, and the transfer efficiency is improved.

FIG. 17 shows P in the above-mentioned optical static elimination.
The change in transfer efficiency with respect to the amount of TL light is shown. In the figure, in the initial stage of image formation shown by the broken line, the transfer efficiency increases with an increase in the PTL light amount in a range where the PTL light amount is small, but is almost saturated when the PTL light amount exceeds a certain value.

In the electrophotographic apparatus, a look-up table is created by associating the amount of decrease in transfer efficiency with the amount of correction of the PTL light amount, and the correction amount obtained by this look-up table is shown by a solid line in FIG. As described above, the amount of PTL light is changed according to the change in transfer efficiency to compensate for the decrease in transfer efficiency. However, if the PTL light amount is increased too much, the fatigue of the photoconductor drum 1 is affected. Therefore, it is necessary to select the light amount that maximizes the transfer efficiency and minimizes the influence on the fatigue of the photoconductor drum 1.

The operation of the process control for stabilizing the image quality in the above configuration will be described.

First, the optical sensor 9 reads the toner patch formed in the initial stage of image formation. At this time, the transfer efficiency determined by the sensor output before and after the transfer is stored in the memory 15 as the reference transfer efficiency. afterwards,
A toner patch is formed every time a certain number of images are formed, and the PTL light amount is controlled so that the transfer efficiency obtained in the same manner as above becomes the reference transfer efficiency. The toner adhesion amount is corrected.

As described above, in the electrophotographic apparatus according to this embodiment, in consideration of the relationship between the PTL light amount and the transfer efficiency, which changes intricately due to the deterioration of the developer and the change of the environment, P
Since the TL light amount is optimally corrected in each situation, it is possible to suppress a decrease in image density.

[Seventh Embodiment] The seventh embodiment of the present invention will be described below with reference to FIGS. 2, 11, 18 and 19.

As shown in FIG. 1, the electrophotographic apparatus according to this embodiment includes a process section formed by the photosensitive drum 1 and the developing device 4 and the like arranged around the photosensitive drum 1. The electrophotographic apparatus also includes a process control unit 27 as shown in FIG. This process control unit 2
7 is an optical sensor 9 and a process control program 28.
And a memory 15 and a CPU 16.

The CPU 16 stores the post-transfer sensor output in the initial stage of image formation in the memory 15 as the remaining amount reference value, and predicts the remaining amount reference value and the expected value of the post-transfer sensor output when performing the image quality stabilizing process in advance. The change rate of the sensor output after transfer is obtained from (experimental value), and the rotation speed of the sleeve rotation motor 29 that rotates the sleeve of the magnet roller 4b is appropriately controlled with respect to this change rate to control the developer supply amount. It is supposed to do. As described above, in the process control unit 27, the CPU 16 controls the process control program 2
By executing step 8, the function as the developer supply amount control means and the function as the reference toner image transfer means are provided.

Here, the relationship between the remaining amount of adhesion and the sleeve rotation speed will be described. The rotation speed here is
The speed at one point on the sleeve (mm / sec). Figure 1
Change rate S '/ S of sensor output after transfer
On the other hand, FIG. 19 shows the sleeve rotation speed at which the developer can be conveyed at the optimum supply amount. In order to keep the toner adhesion amount after the transfer onto the photosensitive drum 1 constant, the sleeve rotation speed is reduced because the remaining amount of toner on the photosensitive drum 1 decreases as S ′ is closer to S from the above characteristics. As the post-transfer sensor output S ′ is smaller than S, the toner remaining amount increases, so that the sleeve rotation speed needs to be increased.

In this electrophotographic apparatus, a look-up table in which the rate of change in the sensor output after transfer and the sleeve rotation speed are associated with each other based on the above relationship is created, and the sleeve rotation speed is obtained from this look-up table. By controlling the sleeve rotation speed in this way, the supply amount of the developer is controlled to compensate for the decrease in transfer efficiency.

The operation of the process control for stabilizing the image quality in the above configuration will be described.

First, when a toner patch is formed on the photosensitive drum 1 after the pre-transfer sensor output is corrected by the toner patch, this toner patch is transferred to the transfer paper.
Then, the post-transfer sensor output S ′ is obtained by the optical sensor 9, and the change rate S ′ / S of the post-transfer sensor output is calculated from the post-transfer sensor output S ′. The sleeve rotation speed is obtained from the above relationship from the change rate S ′ / S, and the sleeve rotation speed is controlled based on this. This allows
The developer is supplied in an amount according to the rate of change S ′ / S, and the amount of toner adhered to the photosensitive drum 1 after transfer is corrected.

As described above, in the electrophotographic apparatus according to this embodiment, the developer supply amount is controlled by controlling the sleeve rotation speed according to the output of the post-transfer sensor, so that the change in the developer is changed. Even if the transfer efficiency changes due to
It is possible to suppress a decrease in image density.

[0095]

As described above, the image quality stabilizing device of the electrophotographic apparatus according to the first to seventh aspects of the present invention transfers the reference toner image formed after the image quality stabilizing control to the transfer paper. While the reference toner image transfer means is provided, the following means is provided for each image quality stabilizing device of the electrophotographic apparatus according to each claim.

An image quality stabilizing device for an electrophotographic apparatus according to a first aspect of the present invention comprises a reference value correcting means for correcting the reference value based on a value detected by the optical detecting means of the toner adhesion amount on the photoconductor after the transfer of the reference toner image. I have it.

When the reference value of the reference toner density is corrected in this way, the process control is performed based on this reference value, so that it is appropriate even if the transfer efficiency changes due to deterioration of the developer or changes in the environment. Image quality can be corrected.

In the image quality stabilizing device for an electrophotographic apparatus according to claim 2 of the present invention, the detection value by the optical detecting means of the toner adhesion amount on the photoconductor after the transfer of the reference toner image is set to the preset remaining amount reference value. As described above, since the transfer output control means for controlling the transfer output is provided, the toner adhesion amount on the photoconductor after the transfer is corrected by the transfer output control, and the image quality is appropriately corrected even if the transfer efficiency changes. It can be performed.

In the image quality stabilizing device for an electrophotographic apparatus according to claim 3 of the present invention, the detection value by the optical detecting means of the toner adhesion amount on the photoconductor after the transfer of the reference toner image is set to the preset remaining amount reference value. Therefore, the transfer output control means for controlling the transfer output and the peeling output control means for controlling the peeling output according to the transfer output controlled by the transfer output control means are provided. By the control, the toner adhesion amount on the photoconductor after the transfer is corrected, and the image quality can be appropriately corrected even if the transfer efficiency changes.
Moreover, since the image quality stabilizing device of the electrophotographic apparatus controls the peeling output in accordance with the transfer output, the peeling defect of the transfer paper and the toner image transfer defect do not occur.

In the image stabilizing device of the electrophotographic apparatus according to the fourth aspect, the value detected by the optical detecting means of the toner adhesion amount on the photoconductor after the transfer of the reference toner image is set to the preset remaining amount reference value. Since the charging output control means for controlling the charging output is provided, the toner adhesion amount on the photoconductor after transfer is corrected by controlling the charging output, and the image quality is appropriately corrected even if the transfer efficiency changes. You can

In the image quality stabilizing device of the electrophotographic apparatus according to the fifth aspect, the detection value by the optical detecting means of the toner adhesion amount on the photoconductor after the transfer of the reference toner image is set to the preset remaining amount reference value. Since the configuration is provided with the pre-transfer charge removal output control unit that controls the output of charge removal performed immediately before transfer, the toner deposition amount on the photoconductor after transfer is corrected by controlling the pre-transfer charge removal output, and transfer efficiency is improved. Even if it changes, the image quality can be properly corrected.

In the image stabilizing device of the electrophotographic apparatus according to the sixth aspect, the detection value by the optical detecting means of the toner adhesion amount on the photoconductor after the transfer of the reference toner image is set to the preset remaining amount reference value. Since it is configured to include a pre-transfer charge removal light amount control unit that controls the light amount of light charge removal performed immediately before transfer, the toner adhesion amount on the photoconductor after transfer is corrected by controlling the light amount of light charge removal before transfer, Even if the transfer efficiency changes, the image quality can be properly corrected.

In the image stabilizing device of the electrophotographic apparatus according to the seventh aspect, the detection value by the optical detecting means of the toner adhesion amount on the photoconductor after the transfer of the reference toner image is set to the preset remaining amount reference value. Since the developer supply amount control means for controlling the supply amount of the developer is provided, the toner adhesion amount on the photoconductor after transfer is corrected by the control of the developer supply amount, and the transfer output changes. Also, the image quality can be properly corrected.

Therefore, the above claims 1 to 7
If the image quality stabilizing device of the electrophotographic apparatus according to the present invention is adopted, there is an effect that the precision of the image quality stabilizing control is improved and a stable formed image can be always obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a process control unit in an electrophotographic apparatus according to a first exemplary embodiment of the present invention.

FIG. 2 is a configuration diagram showing a main part of an electrophotographic process section of an electrophotographic apparatus according to first to seventh embodiments of the present invention.

FIG. 3 is a graph showing the relationship between the number of times of image formation and the image density when the image quality stabilizing process is performed by the process control unit of FIG.

FIG. 4 is a block diagram showing a schematic configuration of a process control unit in an electrophotographic apparatus according to a second exemplary embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a state of transfer and peeling.

FIG. 6 is a graph showing the relationship between transfer output and transfer efficiency.

FIG. 7 is a block diagram showing a schematic configuration of a process control unit in an electrophotographic apparatus according to a third exemplary embodiment of the present invention.

FIG. 8 is a graph showing the relationship between the transfer output and the adhesion of the transfer paper to the photosensitive drum.

FIG. 9 is a graph showing the relationship between transfer output and peeling output.

FIG. 10 is a block diagram showing a schematic configuration of a process control unit in an electrophotographic apparatus according to a fourth exemplary embodiment of the present invention.

FIG. 11 is a graph showing the relationship between sensor output after transfer and image density.

FIG. 12 is a graph showing the relationship between charging output and image density.

FIG. 13 is a block diagram showing a schematic configuration of a process control unit in an electrophotographic apparatus according to a fifth exemplary embodiment of the present invention.

FIG. 14 is a graph showing a relationship between a change rate of a sensor output after transfer and a charge removal output before transfer.

FIG. 15 is a block diagram showing a schematic configuration of a process control unit in an electrophotographic apparatus according to a sixth embodiment of the present invention.

FIG. 16 is an explanatory diagram showing a state in which light is being emitted from the pre-transfer charge eliminating lamp to the photosensitive drum on which a toner image has been formed.

FIG. 17 is a graph showing the relationship between PTL light intensity and transfer efficiency.

FIG. 18 is a block diagram showing a schematic configuration of a process control unit in an electrophotographic apparatus according to a seventh embodiment of the present invention.

FIG. 19 is a graph showing the relationship between the change rate of the sensor output after transfer and the sleeve rotation speed.

[Explanation of symbols]

1 Photoreceptor Drum (Photoreceptor) 2 Charger 2a Grid Electrode 4 Developing Device 4b Magnet Roller 5 Pre-Transfer Charge Eliminating Device 6 Pre-Transfer Electrification Lamp 7 Transfer Device 8 Stripping Device 9 Optical Sensor (Optical Detection Means) 13 Process Control Unit (Reference) Toner image transfer means, reference value correction means) 14 Process control program 15 Memory 16 CPU 17 Process control section (reference toner image transfer means, transfer output control means) 18 Process control program 19 Process control section (reference toner image transfer means, transfer) Output control means, peeling output control means) 20 Process control program 21 Process control section (reference toner image transfer means, charging output control means) 22 Process control program 23 Process control section (reference toner image transfer means, pre-transfer charge elimination output control means) ) 24 Process control program 25 Process Control unit (reference toner image transfer means, the pre-transfer charge removing light amount control means) 26 process control program 27 process control unit (reference toner image transfer means, the developer supply amount control means) 28 process control program 29 sleeve rotating motor

Claims (7)

[Claims] 1. An optical detecting means for optically detecting a toner amount of a reference toner image formed on a photosensitive member, wherein each part of the electrophotographic process is arranged so that the detected value becomes a preset reference value. In an image quality stabilizing device for an electrophotographic apparatus that controls and stabilizes the quality of a formed image, a standard toner image transfer unit that transfers the standard toner image formed after image quality stabilization control to a transfer sheet, and a standard toner image transfer An image quality stabilizing device for an electrophotographic apparatus, comprising: a reference value correcting unit that corrects a reference value based on a detection value of the toner adhesion amount on a subsequent photoconductor by the optical detecting unit. 2. An optical detection means for optically detecting a toner amount of a reference toner image formed on a photosensitive member, wherein each part of the electrophotographic process is arranged so that the detected value becomes a preset reference value. In an image quality stabilizing device for an electrophotographic apparatus that controls and stabilizes the quality of a formed image, a standard toner image transfer unit that transfers the standard toner image formed after image quality stabilization control to a transfer sheet, and a standard toner image transfer An electrophotographic apparatus comprising a transfer output control means for controlling the transfer output so that the detection value of the toner adhesion amount on the subsequent photoconductor by the optical detection means becomes a preset remaining amount reference value. Image stabilization device. 3. An optical detection means for optically detecting a toner amount of a reference toner image formed on a photoconductor, wherein each part of the electrophotographic process is controlled so that the detected value becomes a preset reference value. In an image quality stabilizing device for an electrophotographic apparatus that controls and stabilizes the quality of a formed image, a standard toner image transfer unit that transfers the standard toner image formed after image quality stabilization control to a transfer sheet, and a standard toner image transfer Transfer output control means for controlling the transfer output so that the value detected by the optical detection means of the amount of adhered toner on the subsequent photoconductor becomes a preset remaining amount reference value, and the transfer output control means for controlling the transfer output. An image quality stabilizing device for an electrophotographic apparatus, comprising: a peeling output control unit that controls a peeling output according to an output. 4. An optical detection means for optically detecting a toner amount of a reference toner image formed on a photosensitive member, wherein each part of the electrophotographic process is controlled so that the detected value becomes a preset reference value. An image quality stabilizing device for an electrophotographic apparatus that controls and stabilizes the quality of a formed image. A standard toner image transfer unit that transfers the standard toner image formed after image quality stabilization control to a transfer sheet, and a standard toner image transfer. An electrophotographic apparatus comprising: a charging output control unit that controls a charging output so that a detection value of the toner adhesion amount on the subsequent photoconductor by the optical detection unit becomes a preset remaining amount reference value. Image stabilization device. 5. An optical detection means for optically detecting a toner amount of a reference toner image formed on a photoconductor is provided, and each part of the electrophotographic process is controlled so that the detected value becomes a preset reference value. In an image quality stabilizing device for an electrophotographic apparatus that controls and stabilizes the quality of a formed image, a standard toner image transfer unit that transfers the standard toner image formed after image quality stabilization control to a transfer sheet, and a standard toner image transfer And a pre-transfer charge removal output control means for controlling the output of charge removal performed immediately before transfer so that the detection value of the toner adhesion amount on the subsequent photoconductor by the optical detection means becomes a preset remaining amount reference value. A device for stabilizing the image quality of an electrophotographic device, which is characterized in that 6. An electrophotographic process is provided which has an optical detecting means for optically detecting a toner amount of a reference toner image formed on a photoconductor, and each unit of the electrophotographic process is controlled so that the detected value becomes a preset reference value. In an image quality stabilizing device for an electrophotographic apparatus that controls and stabilizes the quality of a formed image, a standard toner image transfer unit that transfers the standard toner image formed after image quality stabilization control to a transfer sheet, and a standard toner image transfer A pre-transfer charge removal light amount control unit for controlling the light amount of the light charge removal performed immediately before transfer so that the detection value of the toner adhesion amount on the subsequent photoconductor by the optical detection unit becomes a preset remaining amount reference value. An image stabilization device for an electrophotographic device, which is characterized in that 7. An optical detection means for optically detecting a toner amount of a reference toner image formed on a photosensitive member, wherein each part of the electrophotographic process is controlled so that the detected value becomes a preset reference value. In an image quality stabilizing device for an electrophotographic apparatus that controls and stabilizes the quality of a formed image, a standard toner image transfer unit that transfers the standard toner image formed after image quality stabilization control to a transfer sheet, and a standard toner image transfer And a developer supply amount control means for controlling the supply amount of the developer so that the detection value of the toner adhesion amount on the subsequent photoconductor by the optical detection means becomes a preset remaining amount reference value. Image quality stabilizing device for electrophotographic devices.