JPH11119479A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the capacity of a charge-removing equipment to removing charge, to prevent a trouble caused by a deterioration in the capacity to remove charge and to use the measured value of the potential of an electrostatic attracting belt after charge removing precessing, for the control of the operation of the charge removing equipment by measuring the potential. SOLUTION: A paper sheet 10 is electrified together with the electrostatic attracting belt 1, by an electrifying roller 4 and electrostatically attracted to the belt 1. Toner images of each color are transferred to the paper 10 by a transfer roller 54. After the toner images are fixed, an electric charge on the surface of the belt 1 separated from the paper 10 is removed by a charge removing brush 8, to uniformize the distribution of the charge. The potential of the belt 1 after charge removing processing is measured by a potential sensor 9, converted into digital data and then, inputted into a voltage control part 12. Then, a voltage applied to the charge removing brush 8 is decided by the voltage control part 12, to make the potential of the belt 1 after charge removing processing a fixed one and the decided voltage data is converted into an analog signal, to be inputted to a high-voltage power source 14 and applied to the brush 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus such as a copying machine and a facsimile which forms an image on a recording material such as paper by utilizing an electrophotographic method, and more particularly, to an electrostatic device for conveying a recording material. The present invention relates to a static elimination mechanism for making the electric charge distribution on the surface of a conveying means such as an adsorption belt uniform.

[0002]

2. Description of the Related Art In an electrophotographic apparatus such as a copying machine and a facsimile, an electrostatic latent image is formed on a surface of a latent image carrier such as a photosensitive drum using a well-known electrophotographic technique, and the electrostatic latent image is formed by a developing device. Developing to form a toner image on the surface of the photosensitive drum, and a recording material such as a sheet of paper that is charged by a charging unit such as a charging roller together with a conveyance unit such as an electrostatic adsorption belt and electrostatically adsorbed to the electrostatic adsorption belt On the surface of the toner image, the toner image is transferred by a transfer unit such as a transfer roller, and then the sheet on which the toner image is transferred is separated from the electrostatic adsorption belt and transferred to a fixing device.
An image is formed by fixing the toner image on a sheet.

In such a transfer process, a paper is interposed between an electrostatic attraction belt and a photosensitive drum, and an electric field is generated in a direction in which the charged toner is electrostatically attracted to the paper. The transfer roller applies an electric charge to the electrostatic attraction belt. At this time, even if a uniform charge is applied to the electrostatic attraction belt by the transfer roller, due to uneven charging of the electrostatic attraction belt, after the transfer process, as shown in FIG. Depending on the printing, the charge distribution of the electrostatic attraction belt becomes uneven. When the next printing process is performed in such a state, the electric field acting on the charged toner also becomes non-uniform, and uneven transfer occurs, causing an adverse effect such as uneven density on the image formed on the paper.

Therefore, on the downstream side of the cleaning device that removes the adhered matter on the surface of the electrostatic attraction belt, the charge on the surface of the electrostatic attraction belt charged by the transfer roller is removed and its charge distribution (potential). It is known to provide a static eliminator for making the temperature uniform (for example, Japanese Patent Application Laid-Open No. 8-36288). With this static eliminator, as shown in FIG. 10, the non-uniform potential (A in FIG. 10) on the surface of the electrostatic attraction belt is stabilized to a uniform potential (B in FIG. 10) to reduce unevenness in density and the like. Prevent occurrence. The static elimination device includes a static elimination brush,
A static elimination roller or the like is used.

[0005]

However, it is conceivable that the static elimination capability of the static eliminator is reduced due to deterioration in the performance of the static eliminator itself, scraping of the static eliminator, physical deformation, contamination by toner, paper dust, and the like. FIG. 11 shows the potential of the electrostatic attraction belt surface when the static elimination capability of the static eliminator is reduced. The charge on the electrostatic attraction belt surface (A in FIG. 11) having a non-uniform potential after the transfer process is shown. Does not stabilize at a uniform potential (FIG. 11B).

The conventional electrophotographic apparatus does not include a means for detecting a change in the potential of the electrostatic attraction belt after the static elimination process in order to check the static elimination ability of the static elimination apparatus. It was just predicting. As a result, in the conventional electrophotographic apparatus, since the static elimination capability of the static elimination device cannot be accurately grasped, the case occurs when the static elimination capability is reduced.
There is a problem that failures such as transfer failure such as a decrease in transfer efficiency and winding (jam) of the electrostatically attracted paper around the photosensitive drum cannot be prevented beforehand.

[0007] The present invention has been made in view of such circumstances, and is provided with means for measuring the potential of the conveying means (electrostatic attraction belt) after the static elimination processing, so that the static elimination capability of the static elimination means (static elimination device) is provided. Can be accurately detected, and the trouble due to the decrease in the static elimination ability can be prevented beforehand.
An object of the present invention is to provide an electrophotographic apparatus that can use a measured value of the potential for operation control of a static eliminator (static eliminator).

Another object of the present invention is to provide a charging means (charging roller) for charging a recording material (paper) and a transporting means (electrostatic attraction belt) with a transporting means (electrostatic attraction belt) after a static elimination process. ) Has the function of measuring the electric potential, so that the electric potential can be measured using existing members, preventing the trouble due to the decrease in the static elimination ability without increasing the size of the apparatus and increasing the cost, and Another object of the present invention is to provide an electrophotographic apparatus capable of controlling the operation of a static eliminator (static eliminator).

[0009]

According to a first aspect of the present invention, there is provided an electrophotographic apparatus, comprising: conveying means for conveying a recording material; and charging the recording material and the conveying means to transfer the recording material to the recording medium. Charging means for attracting the carrier means, a latent image carrier on which an electrostatic latent image is electronically formed, and developing means for developing the electrostatic latent image on the surface of the latent image carrier into a toner image Transfer means for applying a charge to the transport means for holding the recording material between the latent image carrier and transferring the toner image to the recording material, and the transport means charged by the transfer means An electrophotographic apparatus comprising: a charge elimination unit that removes the electric charge of the surface to make the charge distribution on the surface uniform; and a measurement unit that measures a potential of the transport unit that has been subjected to the charge elimination processing by the charge elimination unit. Features.

In the electrophotographic apparatus according to the first aspect of the present invention, the potential of the conveying means (electrostatic attraction belt) after the charge is removed by the charge removing means (static removing device) is measured by the measuring means, and the measurement result is added to the measurement result. Accordingly, the static elimination capability of the static elimination means (static elimination device) is detected.
Therefore, the static elimination ability of the static eliminator (static eliminator) can be accurately evaluated, the operation of the static eliminator (static eliminator) can be correctly controlled, and the exchange of the static eliminator (static eliminator) when the static elimination capability is reduced can be efficiently performed. I can do it.

According to a second aspect of the present invention, in the electrophotographic apparatus according to the first aspect, the measuring means has means for measuring a voltage of the charging means in a state where no charging voltage is applied. Features.

In the electrophotographic apparatus according to the second aspect of the present invention, the recording medium is charged by a charging means (charging roller) for electrostatically adsorbing the recording material to a conveying means (electrostatic attraction belt) so that the recording material is charged after the static elimination processing. The potential of the transfer means (electrostatic suction belt) is measured. Specifically, the charging device (charging roller) is floated from the frame ground of the apparatus main body without applying a voltage to the charging device (charging roller), and the voltage applied to the charging device (charging roller) is measured to remove the charge. The potential of the conveying means (electrostatic suction belt) after the treatment is measured. Therefore, the potential of the transporting means (electrostatic attraction belt) after the static elimination processing can be measured using the existing charging means (charging roller) without providing a new measuring means. Large bulk and cost increase can be prevented.

According to a third aspect of the present invention, in the electrophotographic apparatus according to the first or second aspect, the static elimination means is a static elimination member whose static elimination effect changes according to an applied voltage; A control means for controlling a voltage applied to the charge removing means based on the control signal.

In the electrophotographic apparatus according to the third aspect of the present invention, the static elimination means (static elimination device) in which the static elimination effect changes according to the applied voltage based on the measured value of the potential of the conveying means (electrostatic attraction belt) after the static elimination processing. 2) feedback control of the applied voltage. Therefore, even if the static elimination ability is slightly reduced, such control can make the surface potential of the transporting means (electrostatic attraction belt) after the static elimination process uniform.

According to a fourth aspect of the present invention, in the electrophotographic apparatus according to the first or second aspect, the static elimination means is a static elimination brush whose static elimination effect changes in accordance with the amount of biting into the transport means. The image forming apparatus further includes a control unit that controls an amount of bite of the neutralization brush into the transport unit based on a measurement value of the measurement unit.

In the electrophotographic apparatus according to the fourth aspect of the present invention, the charge is removed according to the amount of bite into the transfer means (electrostatic attraction belt) based on the measured value of the potential of the transfer means (electrostatic suction belt) after the charge removal processing. Feedback control is performed on the amount of bite of the static elimination means (static elimination brush) whose effect changes. Therefore, even if the static elimination ability is slightly reduced, such control can make the surface potential of the transporting means (electrostatic attraction belt) after the static elimination process uniform.

According to a fifth aspect of the present invention, in the electrophotographic apparatus according to the first or second aspect, the static elimination means is a static elimination roller whose static elimination effect changes in accordance with a pressure on the transport means, And a control unit for controlling the pressure of the charge eliminating roller based on the measurement value of the unit.

In the electrophotographic apparatus according to the fifth aspect of the present invention, the measured value of the potential of the conveying means (electrostatic attraction belt) after the static elimination processing is used in accordance with the pressure applied to the conveying means (electrostatic attraction belt). The feedback of the pressure of the static elimination means (static elimination roller) where f changes. Therefore, even if the static elimination ability is slightly reduced, such control can make the surface potential of the transporting means (electrostatic attraction belt) after the static elimination process uniform.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to an embodiment. In FIG. 1, reference numeral 1 denotes an endless electrostatic attraction belt serving as a transport unit suspended by a plurality of transport rollers 2, which rotates in the direction of the arrow when the transport roller 2 is driven. The electrostatic attraction belt 1 is provided with a paper supply guide plate 3 for supplying paper 10 as a recording material from the paper feeding device (not shown) to the electrostatic attraction belt 1. A charging roller 4 as charging means is provided downstream of the paper supply guide plate 3 in the rotation direction of the electrostatic attraction belt 1. The charging roller 4 charges the electrostatic attraction belt 1 and the paper 10 to form a paper 10. Is electrostatically adsorbed to the electrostatic adsorption belt 1.

A yellow toner image forming unit 5Y for forming a yellow toner image on the paper 10 and a magenta toner image forming unit for forming a magenta toner image on the paper 10 are provided downstream of the charging roller 4 in the rotation direction of the electrostatic attraction belt 1. 5M,
A cyan toner image forming unit 5C for forming a cyan toner image on the sheet 10 and a black toner image forming unit 5B for forming a black toner image on the sheet 10 are sequentially provided. Each of the toner image forming units 5Y, 5M, 5C, and 5B has the same configuration, and includes a photosensitive drum 50, a charger 51, and an exposure device 52.
, Developing unit 53, transfer roller 54, static eliminator 55, and cleaning unit
56 and

On the downstream side in the rotation direction of the electrostatic attraction belt 1 of the black toner image forming unit 5B, the paper 10 on which the toner image has been transferred is separated from the electrostatic attraction belt 1 and guided to a fixing device (not shown). Paper discharge guide plate 6 is provided. Further, a cleaning device 7 for removing the developer, dust and the like attached to the electrostatic attraction belt 1 is provided downstream of the paper discharge guide plate 6 in the rotation direction of the electrostatic attraction belt 1.

On the downstream side of the cleaning device 7 in the rotation direction of the electrostatic attraction belt 1, there is provided a static eliminator for removing charges on the surface of the electrostatic attraction belt 1 and making the charge distribution on the surface of the electrostatic attraction belt 1 uniform. A static elimination brush 8 is provided. The static elimination brush 8 changes its static elimination effect according to the voltage applied to itself. A potential sensor 9 for measuring the potential of the electrostatic attraction belt 1 after the neutralization by the neutralization brush 8 is provided downstream of the neutralization brush 8 in the rotation direction of the electrostatic attraction belt 1.

An A / D converter 11 is connected to the potential sensor 9. The A / D converter 11 converts an analog potential measurement result from the potential sensor 9 into digital potential data, and converts the result into a voltage control unit. Output to 12. The voltage control unit 12 outputs to the D / A converter 13 digital data indicating a voltage to be applied to the neutralization brush 8 according to the digital potential data. D /
The A converter 13 converts the digital data into an analog signal and outputs it to the high voltage power supply 14. The high-voltage power supply 14 applies a voltage corresponding to the input analog signal to the charge removal brush 8.

Next, the operation will be described. Paper 10 is conveyed to the upper surface of the electrostatic attraction belt 1 from a paper feeding device (not shown) via the paper supply guide plate 3. The transported paper 10 is charged by the charging roller 4 together with the electrostatic attraction belt 1, and the paper 10 is electrostatically attracted to the electrostatic attraction belt 1.

4 which rotates at the same speed as the electrostatic attraction belt 1
A toner image of each color is formed on each of the photosensitive drums 50.
That is, the surface of the photosensitive drum 50 is charged by the charger 51, an electrostatic latent image is formed on the surface of the photosensitive drum 50 by the exposure device 52, and the toner of each color is formed on the electrostatic latent image by the developing device 53. The toner is supplied to form a toner image of each color. Then, the toner image of each color in the charged state on the surface of the photosensitive drum 50 is transferred to the paper by the transfer roller 54.
The toner image of each color is moved electrostatically in
Transfer to Paper 10 has four types of toner image forming units 5
When passing through Y, 5M, 5C, and 5B, the above-described processing is performed, and four color toner images (a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image)
Is transferred to the sheet 10. The static eliminator 55 is connected to the photosensitive drum 50
The cleaning device 56 removes the toner remaining on the surface of the photosensitive drum 50.

Paper 10 on which four color toner images are superimposed
Is separated from the electrostatic attraction belt 1 by a curvature, sent to a fixing device (not shown) via the sheet discharge guide plate 6, and the toner image is fixed on the sheet 10 by the fixing device. The cleaning device 7 removes deposits such as developer and dust attached to the surface of the electrostatic attraction belt 1 from which the paper 10 is separated.

Thereafter, the charge on the surface of the electrostatic attraction belt 1 is removed by the charge removing brush 8, and the charge distribution is made uniform. Further, the potential of the electrostatic attraction belt 1 after such a charge elimination process is measured by the potential sensor 9. The measurement result of the potential sensor 9 is converted into digital data by the A / D converter 11, and then input to the voltage control unit 12. Then, the voltage applied to the neutralization brush 8 is determined by the voltage control unit 12 so that the potential of the electrostatic suction belt 1 after the static elimination processing becomes a predetermined potential, and data indicating the voltage is stored in the D / A converter. After being converted to an analog signal in 13, it is input to the high voltage power supply 14,
The determined voltage is applied to the discharging brush 8.

When the neutralizing brush 8 is functioning normally (see FIG. 10), a constant voltage is applied to the neutralizing brush 8 so that the potential of the electrostatic attraction belt 1 can be kept constant. However, when the performance of the static elimination brush 8 is reduced and the potential of the electrostatic attraction belt 1 after the static elimination is fluctuated (FIG.
11), an A / D converter is used by using the measurement result of the potential sensor 9 so that the potential of the electrostatic attraction belt 1 becomes constant.
By operating a feedback circuit composed of 11, a voltage control unit 12, a D / A converter 13, and a high-voltage power supply 14, the voltage value applied to the neutralization brush 8 is controlled. Therefore, the static elimination brush 8
Since the potential of the electrostatic attraction belt 1 is kept constant even when the performance of the electrostatic attraction belt 1 is reduced, it is possible to prevent the deterioration of the transfer performance and the jam caused by the fluctuation of the potential of the electrostatic attraction belt 1 in advance.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to an embodiment. 2, the same members as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 2, reference numeral 8 denotes a static elimination brush as a static elimination device. The static elimination brush 8 varies in the amount of biting into the electrostatic attraction belt 1 due to the movement of the eccentric cam 22 driven by the stepping motor 21. Accordingly, the static elimination effect changes. FIG. 3 is a graph showing the relationship between the amount of bite of the charge elimination brush 8 and the potential of the electrostatic attraction belt 1 after the charge elimination process. The solid line indicates the characteristic of the charge elimination brush 8 having normal charge elimination ability, and the dotted line indicates the charge elimination. This shows the characteristics of the static elimination brush 8 whose performance has been reduced. The driving amount of the stepping motor 21 is controlled by the motor control unit 23 based on the measurement result of the potential sensor 9.

Next, the operation will be described. In addition, paper
The transfer process of the transfer belt 10, the charging process for the electrostatic attraction belt 1 and the sheet 10, the toner image transfer process to the sheet 10, and the like are the same as those in the above-described first embodiment. Only the control operation of the discharging brush 8 based on the measurement result of the sensor 9 will be described.

The electrostatic attraction belt 1 is moved by the neutralizing brush 8
The charge on the surface is removed to make the charge distribution uniform, and the potential of the electrostatic attraction belt 1 after such charge removal processing is measured by the potential sensor 9. The measurement result of the potential sensor 9 is A
After being converted into digital data by the / D converter 11, it is input to the motor control unit 23. Then, the amount of the charge removing brush 8 biting into the electrostatic attraction belt 1 is adjusted so that the potential of the electrostatic attraction belt 1 after the charge removing process becomes a predetermined potential.
The data indicating the bite amount is determined by D / A
After being converted into an analog signal by the converter 13, it is input to the stepping motor 21. Based on this analog signal,
The eccentric cam 22 is moved by the stepping motor 21,
It is controlled to a desired bite amount.

As described above, in the second embodiment, the amount of bite of the static elimination brush 8 into the electrostatic attraction belt 1 is controlled based on the measurement result of the potential sensor 9, and therefore, as in the first embodiment, Even when the performance of the static elimination brush 8 is reduced and the potential of the electrostatic attraction belt 1 after the static elimination process fluctuates, the potential of the electrostatic attraction belt 1 can be kept constant,
A decrease in transfer performance and jam can be prevented in advance.

(Third Embodiment) FIG. 4 shows a third embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to an embodiment. 4, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 4, reference numeral 18 denotes a rubber static elimination roller as a static elimination device.
The pressure (nip (NIP) pressure) fluctuates due to the movement of the eccentric cam 22 driven by the stepping motor 21, and the static elimination effect changes in accordance with the fluctuation of the nip pressure. FIG. 5 is a graph showing the relationship between the nip pressure of the charge removing roller 18 and the potential of the electrostatic attraction belt 1 after the charge removing treatment. The solid line represents the characteristic of the charge removing roller 18 having normal charge removing ability, and the dotted line represents the charge removing charge. This shows the characteristics of the charge eliminating roller 18 whose capacity has been reduced. The driving amount of the stepping motor 21 is controlled by the motor control unit 23 based on the measurement result of the potential sensor 9.

Next, the operation will be described. In addition, paper
The transfer process of the transfer belt 10, the charging process for the electrostatic attraction belt 1 and the sheet 10, the toner image transfer process to the sheet 10, and the like are the same as those in the above-described first embodiment. Static elimination roller based on measurement result of sensor 9
Only the 18 control operations will be described.

The electrostatic attraction belt 1 is moved by the neutralizing roller 18
The charge on the surface is removed to make the charge distribution uniform, and the potential of the electrostatic attraction belt 1 after such charge removal processing is measured by the potential sensor 9. The measurement result of the potential sensor 9 is A
After being converted into digital data by the / D converter 11, it is input to the motor control unit 23. Then, a charge removing roller such that the potential of the electrostatic attraction belt 1 after the charge removal processing becomes a predetermined potential.
The nip pressure 18 is determined by the motor control unit 23, and the data indicating the nip pressure is converted into an analog signal by the D / A converter 13, and then input to the stepping motor 21. Based on this analog signal, a stepping motor
The eccentric cam 22 is moved by 21 and controlled to a desired nip pressure. The nip pressure of the neutralizing roller 18 depends on the rubber hardness of the neutralizing roller 18 and the electrostatic attraction belt 1 of the neutralizing roller 18.
And the amount of bite into

As described above, in the third embodiment, the nip pressure of the charge removing roller 18 with respect to the electrostatic attraction belt 1 is controlled based on the measurement result of the potential sensor 9, and therefore, as in the first embodiment, Even in the case where the performance of the static elimination roller 18 decreases and the potential of the electrostatic attraction belt 1 after the static elimination process fluctuates, the potential of the electrostatic attraction belt 1 can be kept constant.
A decrease in transfer performance and jam can be prevented in advance.

In the above-described first to third embodiments, the electric potential sensor 9 for measuring the electric potential of the electrostatic attraction belt 1 after the static elimination processing is provided. A configuration that adds a function is also possible.
The electrophotographic apparatus of the present invention having such a configuration will be described as the following fourth to sixth embodiments.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to an embodiment. 6, the same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 6, the charging roller 4 is
It is a conductive rubber roller, its electric resistance is 10 ⁸ Ω or less, and its rubber hardness is 90 ° according to Asker C of JIS standard.
It is as follows. In order to measure the potential of the electrostatic attraction belt 1 after the charge elimination processing by the charging roller 4, it is necessary that the electrostatic attraction belt 1 and the charging roller 4 have substantially the same potential.
If the resistance of the charging roller 4 is high, a voltage drop occurs and the electrostatic attraction belt 1 and the charging roller 4 are not at the same potential. Therefore, the electric resistance of the charging roller 4 is set to 10 ⁸ Ω or less. In order to measure the potential of the electrostatic attraction belt 1 after the static elimination process,
It is necessary to increase the adhesion of the charging roller 4 to the electrostatic attraction belt 1, and the hardness of the charging roller 4 is set to 90 ° or less so that the contact with the electrostatic attraction belt 1 can be maintained uniformly.

A voltmeter 31 measures the voltage applied to the charging roller 4, and a switch 32 controls whether or not a voltage is applied to the charging roller 4. The charging roller 4 according to the fourth embodiment has a function of adsorbing the sheet 10 to the electrostatic attraction belt 1 similarly to the first to third embodiments, and also has a function of adjusting the potential of the electrostatic attraction belt 1 after the static elimination processing. Has a function to measure. That is, the voltage applied to the charging roller 4 is measured by the voltmeter 31 in a state where the switch 32 is turned off and no voltage is applied to the charging roller 4 and the charging roller 4 is floated from the frame ground on the apparatus main body side. Thus, the potential of the electrostatic attraction belt 1 after the charge removal processing can be measured.

The static elimination brush 8 shown in FIG.
The charge removal effect changes in accordance with the change in the voltage applied to the charge removal brush 8.

Next, the operation will be described. In addition, paper
The process of transporting the sheet 10, the process of charging the electrostatic attraction belt 1 and the sheet 10, the process of transferring the toner image to the sheet 10, and the like are the same as those in the first embodiment described above. Only the control operation of the discharging brush 8 based on the measurement results by the roller 4 and the voltmeter 31 will be described.

The charge on the surface of the electrostatic attraction belt 1 is removed by the charge removing brush 8, and the charge distribution is made uniform. After the neutralization process, the switch 32 is turned off, no voltage is applied to the charging roller 4, and the voltage applied to the charging roller 4 is measured by the voltmeter 31 with the charging roller 4 floating above the frame ground. The measurement result of the voltmeter 31 is converted into digital data by the A / D converter 11 and then converted to a voltage control unit.
Entered in 12. The voltage applied to the neutralization brush 8 is determined by the voltage control unit 12 so that the potential of the electrostatic attraction belt 1 after the neutralization processing becomes a predetermined potential, and the data indicating the voltage is stored in the D / A converter. After being converted into an analog signal at 13, the signal is input to the high voltage power supply 14, and the determined voltage is applied to the neutralization brush 8.

As described above, in the fourth embodiment, the first
As in the embodiment, the voltage value applied to the neutralization brush 8 is controlled based on the measured potential of the electrostatic attraction belt 1,
The potential of the electrostatic attraction belt 1 can be kept constant even if the performance of the static elimination brush 8 is reduced, and the deterioration of the transfer performance and the jam caused by the fluctuation of the potential of the electrostatic attraction belt 1 can be prevented in advance.

(Fifth Embodiment) FIG. 7 shows a fifth embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to an embodiment. 7, the same members as those in FIGS. 1, 2, and 6 are denoted by the same reference numerals, and description thereof will be omitted. The charging roller 4 in FIG. 7 is the same as that in the fourth embodiment shown in FIG. 6, and has a function of measuring the potential of the electrostatic attraction belt 1 after the static elimination processing in addition to the electrostatic attraction function of the paper 10. Having. The static elimination brush 8 in FIG. 7 is the same as that in the second embodiment shown in FIG. 2, and the eccentric cam 22 driven by the stepping motor 21 moves the eccentric cam 22 so that the amount of biting into the electrostatic attraction belt 1 varies. Depending on the fluctuation of the bite amount,
The static elimination effect changes.

Next, the operation will be described. In addition, paper
The process of transporting the sheet 10, the process of charging the electrostatic attraction belt 1 and the sheet 10, the process of transferring the toner image to the sheet 10, and the like are the same as those in the first embodiment described above. Only the control operation of the discharging brush 8 based on the measurement results by the roller 4 and the voltmeter 31 will be described.

The charge on the surface of the electrostatic attraction belt 1 is removed by the charge removing brush 8 so that the charge distribution is made uniform. After the neutralization processing, the switch 32 is turned off, no voltage is applied to the charging roller 4, and the voltage applied to the charging roller 4 is measured by the voltmeter 31 with the charging roller 4 floating above the frame ground. The measurement result of the voltmeter 31 is converted into digital data by the A / D converter 11 and then input to the motor control unit 23. Then, the motor control unit 23 determines the amount of bite of the charge removing brush 8 into the electrostatic attraction belt 1 such that the potential of the electrostatic attraction belt 1 after the charge removal processing becomes a predetermined potential, and data indicating the bite amount. Is a D / A converter
After being converted to an analog signal at 13, the stepping motor
Entered in 21. The eccentric cam 22 is moved by the stepping motor 21 based on the analog signal, and is controlled to a desired bite amount.

As described above, in the fifth embodiment, the second
In the same manner as in the embodiment, the bite of the static elimination brush 8 into the electrostatic attraction belt 1 is controlled based on the measured potential of the electrostatic attraction belt 1. 1 can be kept constant, and a decrease in transfer performance and a jam caused by a change in the potential of the electrostatic attraction belt 1 can be prevented in advance.

(Sixth Embodiment) FIG. 8 shows a sixth embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to an embodiment. 8, the same members as those in FIGS. 1, 4, and 6 are denoted by the same reference numerals, and description thereof will be omitted. The charging roller 4 in FIG. 8 is the same as that in the fourth embodiment shown in FIG. 6, and has a function of measuring the potential of the electrostatic attraction belt 1 after the static elimination processing in addition to the electrostatic attraction function of the paper 10. Having. Further, the charge removing roller 18 in FIG. 8 is the same as that in the third embodiment shown in FIG. 4, and the nip pressure fluctuates due to the movement of the eccentric cam 22 driven by the stepping motor 21, and the nip pressure fluctuates. Accordingly, the static elimination effect changes.

Next, the operation will be described. In addition, paper
The transfer process of the transfer belt 10, the charging process for the electrostatic attraction belt 1 and the paper 10, the toner image transfer process to the paper 10, and the like are the same as those in the above-described first embodiment. Only the control operation of the charge removing roller 18 based on the measurement results by the roller 4 and the voltmeter 31 will be described.

The electrostatic attraction belt 1 is moved by the discharging roller 18
The charge on the surface is removed, and the charge distribution is made uniform.
After the neutralization process, the switch 32 is turned off and the charging roller 4 is turned off.
The voltage applied to the charging roller 4 is measured with the charging roller 4 floating above the frame ground without applying a voltage to the voltmeter.
Measure at 31. The measurement result of the voltmeter 31 is an A / D converter
After being converted to digital data in 11, the motor control unit 23
Is input to Then, the electrostatic suction belt 1 after the static elimination process
The nip pressure of the charge removing roller 18 is determined by the motor control unit 23 so that the potential of the elimination roller 18 becomes a predetermined potential, and the data indicating the nip pressure is converted into an analog signal by the D / A converter 13, and then the stepping is performed. Input to the motor 21. The eccentric cam 22 is moved by the stepping motor 21 based on the analog signal, and is controlled to a desired nip pressure.
The nip pressure of the charge removing roller 18 is calculated based on the rubber hardness of the charge removing roller 18 and the amount of the charge removing roller 18 biting into the electrostatic attraction belt 1.

As described above, in the sixth embodiment, the third
As in the embodiment, the nip pressure of the static elimination roller 18 with respect to the electrostatic adsorption belt 1 is controlled based on the measured potential of the electrostatic adsorption belt 1. 1 can be kept constant, and a decrease in transfer performance and a jam caused by a change in the potential of the electrostatic attraction belt 1 can be prevented in advance.

The control operation of the static elimination device (the static elimination brush 8 or the static elimination roller 18) in the above-described fourth to sixth embodiments is not performed during the printing operation. This processing is performed at the time of non-printing operation such as before and after processing and between sheets so as not to hinder the printing operation. It is generally not conceivable that the static elimination capability of the static eliminator suddenly decreases, and thus there is no particular problem.

In the above-described fourth to sixth embodiments, a conductive rubber roller is used as the charging roller 4, but a roller made of another material may be used. When a roller having a hardness of 90 ° or more, such as a metal roller, is used as the charging roller 4, the charging roller 4 made of the metal roller is used.
A conductive rubber roller having an electrical resistance of 10 ⁸ Ω or less and a hardness of 90 ° or less is used as the transport roller 2 which faces through the electrostatic attraction belt 1.

In each of the above-described embodiments, the paper 10
Although the electrostatic attraction belt 1 is used as a transporting means for transporting the toner, a rotating drum may be used.

[0056]

As described above, in the electrophotographic apparatus according to the first aspect of the present invention, since the measuring means for measuring the potential of the conveying means after the static elimination processing is provided, the neutralization of the static elimination means is performed based on the measurement result of the measuring means. Capability can be accurately detected, preventing problems due to a decrease in static elimination capability, and
The measured value of the potential can be used for controlling the operation of the static elimination means, and a replacement request for the static elimination means can be made at an optimal time.

In the electrophotographic apparatus according to the second aspect of the present invention, the charging means has a function of measuring the potential of the conveying means after the charge elimination process in addition to the function of electrostatically adhering the recording material to the conveying means. It is possible to measure the potential of the transporting means using existing members without providing any means, and to prevent a failure due to a reduction in static elimination capability and to operate the static elimination means without incurring an increase in apparatus configuration and cost. It is possible to control.

In the electrophotographic apparatus according to the third aspect of the present invention, the applied voltage of the charge removing means whose charge removing effect changes in accordance with the applied voltage is feedback-controlled based on the measured value of the potential of the transfer means after charge removal. Even if the capacity is slightly reduced, such a control makes it possible to make the electric field distribution on the surface of the conveying means after the charge elimination uniform.

In the electrophotographic apparatus according to the fourth aspect of the present invention, the amount of digging of the charge eliminator, whose charge elimination effect changes according to the amount of digging into the transfer means, is feedback-controlled based on the measured value of the potential of the transfer means after charge elimination. Therefore, even if the static elimination ability is slightly reduced, such a control can make the electric field distribution on the surface of the conveying means after static elimination uniform.

In the electrophotographic apparatus according to the fifth aspect of the invention, the pressure of the static eliminator, whose static elimination effect changes in accordance with the pressure on the transport means, is feedback-controlled based on the measured value of the potential of the transport means after static elimination. Even if the static elimination ability is slightly reduced, such control can make the electric field distribution on the surface of the conveying means after static elimination uniform.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to a first embodiment.

FIG. 2 is a schematic configuration diagram of an electrophotographic apparatus according to a second embodiment.

FIG. 3 is a graph showing a relationship between a bite amount of a charge removing brush and a potential of an electrostatic attraction belt after a charge removing process.

FIG. 4 is a schematic configuration diagram of an electrophotographic apparatus according to a third embodiment.

FIG. 5 is a graph showing a relationship between a nip pressure of a charge removing roller and a potential of an electrostatic attraction belt after a charge removing process.

FIG. 6 is a schematic configuration diagram of an electrophotographic apparatus according to a fourth embodiment.

FIG. 7 is a schematic configuration diagram of an electrophotographic apparatus according to a fifth embodiment.

FIG. 8 is a schematic configuration diagram of an electrophotographic apparatus according to a sixth embodiment.

FIG. 9 is a graph showing a non-uniform potential in the electrostatic attraction belt.

FIG. 10 is a graph showing the potential of the electrostatic attraction belt when the static elimination capability of the static elimination device is normal.

FIG. 11 is a graph showing the potential of the electrostatic attraction belt when the static elimination capability of the static eliminator is reduced.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrostatic adsorption belt (conveying means) 4 Charging roller (charging means) 8 Static elimination brush (static elimination means) 9 Potential sensor (measuring means) 10 Paper (recording material) 12 Voltage control unit 14 High voltage power supply 18 Static elimination roller (static elimination means) 21) Stepping motor 22 Eccentric cam 23 Motor control unit 31 Voltmeter 50 Photosensitive drum (latent image carrier) 53 Developing unit (developing unit) 54 Transfer roller (transfer unit)

Claims (5)

[Claims] A transporting means for transporting a recording material; a charging means for charging the recording material and the transporting means to attract the recording material to the transporting means; A latent image carrier on which an image is formed; developing means for developing the electrostatic latent image on the surface of the latent image carrier into a toner image; and the transport for holding the recording material between the latent image carrier Transfer means for applying a charge to the means to transfer the toner image to the recording material; and a charge removing means for removing the charge of the transport means charged by the transfer means to make the charge distribution on the surface uniform. An electrophotographic apparatus comprising: a measuring unit that measures a potential of the transporting unit that has been subjected to the static elimination processing by the static elimination unit. 2. The electrophotographic apparatus according to claim 1, wherein said measuring means has means for measuring a voltage of said charging means in a state where no charging voltage is applied. 3. The static eliminator is a static eliminator whose static elimination effect changes according to an applied voltage, and further includes control means for controlling a voltage applied to the static eliminator based on a measurement value of the measuring means. Item 3. The electrophotographic apparatus according to item 1 or 2. 4. The static elimination means is a static elimination brush whose static elimination effect changes according to the amount of bite into the transport means,
3. The electrophotographic apparatus according to claim 1, further comprising a control unit configured to control an amount of biting of the charge removing brush into the transport unit based on a measurement value of the measurement unit. 4. 5. The static elimination means is a static elimination roller whose static elimination effect changes according to the pressure on the transport means, and further includes a control means for controlling the pressure of the static elimination roller based on a measurement value of the measuring means. The electrophotographic apparatus according to claim 1 or 2, further comprising: