JPH05113711A - Electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To provide an electrophotographic copying machine capable of easily setting the relationship between the surface potential of a photoconductor and the applied voltage to an electrostatic charger. CONSTITUTION:When a start switch is pressed in a step ST1, the specified voltage is applied to an electrostatic charger to charge the surface of a sensitized body in a step ST2. In a step ST3, the surface potential of the sensitized body is measured by a measuring device. In a step ST4, whether the measured value is equal to the specified voltage value is judged. In the case of being unequal to the specified voltage value, proceeding to a step ST5 is performed. In the case of being equal to the specified voltage value, proceeding to a step ST6 is performed. In the step ST5, the voltage to be applied to the electrostatic charger is reset, then the return to the step ST3 is performed after applying the reset voltage, and this action is repeated until the measured value becomes equal to the specified voltage value. In the step ST6, a variable alpha is obtained in a function (Y=X+alpha) materialized between the sensitized body surface potential X and the electrostatic charger applied voltage Y. In a step ST7, the obtained relational expression is stored into a memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine, and more particularly to an electrophotographic copying machine suitable for full-color copying.

[0002]

2. Description of the Related Art In a conventional electrophotographic copying machine, in order to form an image of a document on a recording medium (final recording medium such as paper), the document is first illuminated by a light source lamp or the like, and light reflected from the document is reflected. Is irradiated onto the photoconductor uniformly charged by the charging charger through the mirror and the lens. The photoconductor is exposed by receiving the reflected light from the document, and an electrostatic latent image having a pattern corresponding to the document image is formed on the surface of the photoconductor.

Then, the electrostatic latent image is visualized as a toner image by the toner, and the toner image is transferred to the intermediate transfer member. The toner image transferred to the intermediate transfer member is transferred to the recording medium. Thereafter, the toner image on the recording medium is fused, and the copying is completed.

A conventional electrophotographic copying machine has a large number of copying modes such as a monochrome mode for performing black-and-white copying, a color mode for performing color copying, a photo mode for emphasizing gradation and a graphic mode for emphasizing shading. Some have. In such an electrophotographic copying machine, the voltage applied to the charger with respect to the surface potential of the photoconductor is set for each copy mode in the initial adjustment during production.

FIG. 6 is a graph showing the relationship between the photoreceptor surface potential (X) and the charging charger applied voltage (Y).

That is, as shown in the figure, in each of a plurality of copying modes (1), (2), (3) and (4), the photoreceptor surface potential (X) is A, B, C and D. The values a, b, c and d of the charging charger applied voltage (Y) are set so that

[0007]

In such a conventional electrophotographic copying machine, the voltage applied to the charger must be set so as to obtain a desired surface potential of the photoconductor for each copying mode. Therefore, there is a problem that it takes time and effort for setting.

Therefore, the present invention provides an electrophotographic copying machine in which the relationship between the surface potential of the photosensitive member and the voltage applied to the charging charger can be easily set.

[0009]

A photosensitive member, a charging unit for charging the photosensitive member, an image forming unit for forming a toner image formed on the photosensitive member on a sheet according to an original image, and a charging unit. Measuring means for measuring the potential of the photoconductor,
The applied voltage value to the charging means is obtained so that the potential measured by the measuring means becomes equal to the predetermined potential, and the charging potential of the photoconductor and the application to the charging means are determined based on the obtained applied voltage value and the predetermined potential. And a setting means for setting a relational expression with respect to the voltage.

[0010]

The toner image formed according to the original image on the photoconductor charged by the charging means is formed as a copy image on the paper by the image forming means. When setting the relationship between the charging potential of the photoconductor and the voltage applied to the charging means necessary for such copying, the potential of the photoconductor charged by the charging means is measured by the measuring means. The control means obtains an applied voltage value to the charging means so that the measured potential of the photoconductor becomes equal to a predetermined potential, and based on the thus obtained applied voltage value and the predetermined potential of the photoconductor, A relational expression between the charging potential and the voltage applied to the charging means is set.
Since this relational expression can be set in one copy mode, it is not necessary to make adjustments to set the relational expression for each of a plurality of copy modes. Therefore, the relationship between the charging potential of the photoconductor and the voltage applied to the charging means can be easily set.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a side view showing the construction of a full-color copying machine which is an embodiment of the electrophotographic copying machine according to the present invention.

As shown in FIG. 2, the full-color copying machine 10 of this embodiment is provided with an original table 11 made of transparent glass on the upper surface of the machine frame.

An exposure optical system 12 is arranged below the document table 11. The exposure optical system 12 includes a light source lamp 12a for irradiating the original 13 placed on the original placing table 11 with light, and the original 13
A plurality of reflecting mirrors 12b, 12c, 12d, 12e for guiding the reflected light from the photoconductor 14 along the optical path indicated by the alternate long and short dash line and
12f, an imaging lens 12g arranged on the optical path, and a color separation filter 12 having color filters of three primary colors of red, green and blue.
contains h and.

The light source lamp 12a and the reflecting mirrors 12b, 12c and 12
d is configured to be movable in parallel with the document placing table 11 along a bidirectional arrow shown in the drawing by a driving device (not shown).

On the optical axis of the exposure optical system 12, there is arranged a drum-shaped photosensitive member 14 made of an organic photosensitive member (OPC) which is irradiated with a light image subjected to exposure scanning.

Below the photoconductor 14, a paper 15 is stored.
Two paper feed cassettes 16 and 17 are provided. Paper feed rollers 18 and 19 are provided on the upper surfaces of the paper feed cassettes 16 and 17, respectively.

The paper feed rollers 18 and 19 are constructed so as to eject the paper 15 from the paper feed cassettes 16 and 17, respectively, and feed it toward the intermediate transfer body 20.

A timing roller 21 is provided on the delivery side of the paper 15 from the paper feed rollers 18 and 19 toward the intermediate transfer body 20, and the timing roller 21 rotates in synchronization with the intermediate transfer body 20. Is configured.

The intermediate transfer member 20 is configured to be rotationally driven in the clockwise direction (arrow shown in the figure) by the first, second and third rollers 22a, 22b and 22c. Is partially pressed against the photoconductor 14.

A primary transfer charger 23 is provided on the back surface side of the intermediate transfer member 20 in the portion where the intermediate transfer member 20 is pressed against the photosensitive member 14.

A secondary transfer roller 25 is disposed on the surface side of the intermediate transfer body 20 in a portion where the third roller 22c is disposed so as to be in contact with the intermediate transfer body 20.

On the side of the secondary transfer roller 25 where the paper 15 is delivered,
The peeling plate 26, the transport belt 27, and the fixing device 28 are
They are arranged in this order.

The photoconductor 14 irradiated with the reflected light from the exposure optical system 12 is configured to be rotationally driven in the counterclockwise direction (arrow shown in the figure).

The intermediate transfer member 20 remains on the photosensitive member 14 between the portion where it is pressed against the photosensitive member 14 and the exposure position P where the reflected light from the exposure optical system 12 is applied to the photosensitive member 14. A cleaning device 29 for removing the toner, a discharging lamp unit 30 for discharging the photoconductor 14, and a charger 31 for charging the photoconductor 14 are arranged in this order along the rotation direction of the photoconductor 14.

The photoconductor 14 is not contacted between the exposure position P where the reflected light from the exposure optical system 12 is applied to the photoconductor 14 and the portion where the intermediate transfer body 20 is pressed against the photoconductor 14. In this state, the black and white developing tank 32 and the color developing tanks 33, 34 and 35 are arranged in this order along the rotation direction of the photoconductor 14. The color developing tanks 33, 34, and 35 contain yellow, magenta, and cyan color developers, respectively.

A surface potential measuring device 36 for measuring the surface potential of the photoconductor 14 charged by the charging charger 31 is arranged between the charging charger 31 and the exposure position P.

Next, the operation of the full-color copying machine 10 of this embodiment will be described.

When a copy start switch (not shown) provided in the full-color copying machine 10 is pressed, for example, a color mode for performing color copying is executed. This copy mode has a copy cycle in which yellow, magenta, and cyan are developed and transferred to the intermediate transfer body 20, and when the copy mode is executed, the yellow copy cycle is executed first.

That is, the original document 13 placed on the original document table 11
On the other hand, light is emitted from the light source lamp 12a to perform exposure scanning. The reflected light from the original 13 is passed through the reflecting mirrors 12b, 12c and 12d and the image forming lens 12g, and the color separation filter 12
Separated by h by color component.

The color separation filter 12 is obtained by the above-described exposure scanning.
The light for each color component transmitted through each color filter of h is reflected by the reflecting mirror 12e.
And 12f to irradiate the photoconductor 14 uniformly charged by the charging charger 31, and the photoconductor 14 is exposed at the P portion.

The voltage applied to the charger 31 for charging the photoconductor 14 at this time is set by a setting device described later.

By the exposure at the P portion, a yellow electrostatic latent image corresponding to the image of the original 13 is formed on the photoconductor 14. This electrostatic latent image is developed and visualized by the developer supplied by the developing magnet roller 33a at a portion opposite to the developing tank 33 having a yellow developer which is a complementary color of the color separation filter 12h, and becomes a toner image. This toner image is transferred to the intermediate transfer body 20 by the primary transfer charger 23.

At the end of this yellow copying cycle,
The photoconductor 14 is cleaned by the cleaning device 29, and the charge is removed by the charge removal lamp unit 30.

After that, the magenta and cyan toner images are transferred to the intermediate transfer body 20 in a copy cycle similar to the yellow copy cycle described above.

Therefore, when the yellow, magenta, and cyan copying cycles are executed, the toner image for each color component is transferred to the same position on the intermediate transfer member 20 by the primary transfer charger 23, and the toner for each color component is transferred. The toner images are completed by superimposing the images.

On the other hand, the papers 15 accommodated in the paper feed cassettes 16 and 17 are fed one by one to the timing roller 21 by the paper feed rollers 18 and 19, and the timing roller 21 is synchronized with the rotational driving of the intermediate transfer member 20. Then, the paper 15 is conveyed between the intermediate transfer body 20 and the secondary transfer roller 25.

After the toner image formed on the intermediate transfer body 20 is transferred by the secondary transfer roller 25 to the conveyed paper 15, the sheet 15 is separated from the intermediate transfer body 20 by the peeling plate 26 and is fixed by the transport belt 27. Introduced to 28.

After the toner image is fixed on the paper 15 by the fixing device 28, the paper 15 is ejected to the outside, whereby the one-time copying mode ends.

Next, the relationship between the surface potential of the photosensitive member 14 and the voltage applied to the charging charger 31, which is obtained by an experiment using the full-color copying machine 10 of this embodiment, will be described.

FIG. 3 is a graph showing the relationship between the photoconductor surface potential (X) and the charging charger applied voltage (Y) measured by experiments.

In the figure, under predetermined process conditions,
For example, the photosensitive member surface potential (X) with respect to the charging charger applied voltage (Y) in each copying mode such as a monochrome mode for performing black-and-white copying, a color mode for performing color copying, a photo mode for emphasizing gradation and a graphic mode for emphasizing gradation ) Is shown (three straight lines measured under three process conditions).

As a result, it has been found that there is a relation generally expressed by the following relational expression between the photoreceptor surface potential (X) and the charging charger applied voltage (Y).

Y = X + α (α is a variable) That is, the charging charger applied voltage (Y) is a linear function of the photoconductor surface potential (X).

Next, a setting device for setting the relationship of the charging charger applied voltage (Y) with respect to the photoreceptor surface potential (X) will be described.

FIG. 4 is a block diagram showing an embodiment of the configuration of this setting device.

As shown in the figure, the setting device 50 of this embodiment comprises a CPU (central processing unit) 51, a RAM (random access memory) 52 and a ROM (read only memory) 53.

The CPU 51 includes a RAM 52, a ROM 53, and FIG.
Are connected to the charging charger 31 and the surface potential measuring device 36 for measuring the surface potential of the photoconductor 14, respectively.

As described above, the ROM 53 has a function type, that is, a relation of Y = X + α (linear function) that is established between the surface potential (X) of the photoconductor and the voltage (Y) applied to the charger, and the relationship of the photoconductor. A predetermined voltage value corresponding to the surface potential is stored.

The photoconductor 14 is an example of the photoconductor of the present invention. The intermediate transfer body 20, the primary transfer charger 23, the secondary transfer roller 25, the peeling plate 26, the conveying belt 27, and the fixing device 28 are examples of the image forming means of the present invention. The charging charger 31 is an embodiment of the charging means of the present invention. The surface potential measuring device 36 is an embodiment of the measuring means of the present invention. The setting device 50 is an embodiment of the setting means of the present invention.

Next, the operation of the setting device 50 for setting the relationship between the surface potential of the photosensitive member 14 and the voltage applied to the charger 31 will be described.

FIG. 1 shows a setting device 50, especially a setting device.
6 is a flowchart showing an operation of a CPU 51 included in 50.

Here, the full-color copying machine 10 shown in FIG. 2 is used.
The operation in one copy mode among the plurality of copy modes of the above will be described.

As shown in FIG. 1, first, in step ST1, application to the charger 31 with respect to the surface potential of the photoconductor 14 via the operation panel (not shown) provided in the full-color copying machine 10 of FIG. It is determined whether or not the start switch for setting the voltage relationship is pressed (turned on). If it is determined that this start switch is turned on, the process proceeds to step ST2, and if it is determined that it is not turned on, the operation ends.

Next, in step ST2, a predetermined voltage is applied to the charger 31 to charge the surface of the photoconductor 14.

Next, in step ST3, the surface potential of the photoconductor 14 is measured by the surface potential measuring device 36.

Next, in step ST4, a predetermined voltage value corresponding to the surface potential of the photoconductor 14 is read from the ROM 53, and the photoconductor measured by the surface potential measuring device 36 is read.
It is determined whether the value of the surface potential of 14 is equal to the read predetermined voltage value. If it is determined that the measured value is not equal to the predetermined voltage value, the process proceeds to step ST5, and if it is determined that the measured value is equal to the predetermined voltage value, the process proceeds to step ST6.

In step ST5, the voltage to be applied to the charger 31 is reset according to whether the measured value of the surface potential of the photoconductor 14 is larger or smaller than a predetermined voltage value, and the reset voltage is charged. Apply it to the charger 31 and return to step ST3.

Thereafter, in step ST4, the operations of steps ST5 and ST3 are repeated until it is determined that the measured value of the surface potential of the photoconductor 14 is equal to the predetermined voltage value.

As a method of resetting the voltage to be applied to the charger 31 in step ST5, for example, depending on whether the measured value of the surface potential of the photoconductor 14 is larger or smaller than a predetermined voltage value. Then, it may be set by reducing or adding a predetermined amount to the previously applied voltage value.

Step ST6 executed when it is determined in step ST4 that the measured value is equal to the predetermined voltage value
Then, the photoconductor surface potential (X) stored in the ROM 53.
And the voltage applied to the charging charger (Y), that is, a function type, that is, a relation of Y = X + α (linear function) is read out. In this function, let X be the measured value of the surface potential of the photosensitive member 14 or the above-mentioned predetermined voltage value, and Y be the voltage value applied to the charger 31 when the measured value becomes equal to the predetermined voltage value. , Obtain the variable α.

Thus, the relational expression between the surface potential of the photosensitive member 14 and the voltage applied to the charging charger 31 is obtained.

Then, in step ST7, the obtained relational expression is stored in the memory, that is, the RANM 52 shown in FIG.

FIG. 5 is a graph showing the relationship between the photoreceptor surface potential and the charging charger applied voltage obtained as a result of the operation of the setting device 50.

As shown in the figure, the above-mentioned operation is
In one copy mode (1), the charging charger applied voltage (Y) is set to a'so that the photosensitive member surface potential (X) becomes A ', and the relational expression of Y = X + α is determined. From the relational expression thus obtained
To the charging charger (Y) where the photosensitive member surface potential (X) in the copying modes (2), (3), (4), etc. other than the mode (1) becomes B ', C', D '... Applied voltage values b ′, c ′, d ′ ...
Can be determined respectively.

Therefore, the relationship between the surface potential of the photoconductor that can be used in a plurality of copy modes and the voltage applied to the charging charger can be easily set in one copy mode. Therefore, it is not necessary to adjust each mode as many as the number of copy modes of the copying machine as in the conventional case, and time and labor are not required for setting.

In the above embodiment, an example of obtaining the relational expression between the photosensitive member surface potential and the charging charger applied voltage in one copy mode (1) has been shown, but it is used to obtain the relational expression. Copy mode is not limited to this mode, ROM
If a predetermined voltage value on the surface of the photoconductor corresponding to the copy mode is stored in 53, the relational expression may be obtained using any copy mode of the copying machine.

The operation based on the flowchart for setting the relationship between the surface potential of the photoconductor shown in FIG. 1 and the voltage applied to the charger is preprogrammed, and the program is stored in the ROM 53 of FIG. There is. The program stored in the ROM 53 can be read and executed by the CPU 51.

[0069]

As described above, according to the present invention, the photoconductor, the charging means for charging the photoconductor, and the image forming means for forming the toner image formed on the photoconductor on the paper according to the original image. And a measuring means for measuring the potential of the photoconductor charged by the charging means, and an applied voltage obtained while obtaining an applied voltage value to the charging means such that the potential measured by the measuring means becomes equal to a predetermined potential. Since the setting means for setting the relational expression between the charging potential of the photoconductor and the voltage applied to the charging means on the basis of the value and the predetermined potential is provided, therefore, the charging potential of the photoconductor and the voltage applied to the charging means. The relationship with can be set easily.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation of a setting device.

FIG. 2 is a side view showing the configuration of a full-color copying machine which is an embodiment of the electrophotographic copying machine according to the present invention.

FIG. 3 is a graph showing a relationship between a photosensitive member surface potential measured by an experiment and a charging charger applied voltage.

FIG. 4 is a block configuration diagram showing an example of a configuration of a setting device.

FIG. 5 is a graph showing the relationship between the photoreceptor surface potential and the charging charger applied voltage obtained as a result of the operation of the setting device.

FIG. 6 is a graph showing the relationship between the photoreceptor surface potential and the voltage applied to the charger.

[Explanation of symbols]

 10 Full-color copying machine 14 Photoconductor 20 Intermediate transfer member 23 Primary transfer charger 25 Secondary transfer roller 26 Peeling plate 27 Conveyor belt 28 Fixing device 31 Charging charger 36 Surface potential measuring device 50 Setting device 51 CPU

Claims (1)

[Claims] 1. A photoconductor, a charging unit for charging the photoconductor, an image forming unit for forming a toner image formed on the photoconductor on a sheet according to an original image, and a charging unit for charging the image. Measuring means for measuring the electric potential of the photoconductor,
The applied voltage value to the charging means is obtained such that the potential measured by the measuring means becomes equal to a predetermined potential, and the charging potential of the photoconductor is determined based on the obtained applied voltage value and the predetermined potential. An electrophotographic copying machine comprising: setting means for setting a relational expression with respect to the voltage applied to the charging means.