JPH05188837A - Image forming device - Google Patents

Abstract

(57) [Summary] [Purpose] To stabilize the image quality by detecting the amount of stains on the charge wire for destaticization processing and automatically performing correction or treatment based on the amount of stains. A potential sensor 111 for detecting a surface potential of a photosensitive drum 101 in a main scanning direction, a QL 108 in which light emitting members are arranged in a main scanning direction of a photosensitive band, and a potential sensor 1
11, the surface potential data at a plurality of locations on the photosensitive drum 101 detected by 11 are averaged, and a decrease in the average value of the section with respect to the average value is determined as the amount of contamination of the charge wire of the charger 102. The control unit 300 controls the supply voltage to the charge wire for the corresponding section based on the amount of contamination determined by the control unit 300.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a laser printer which uses an electrophotographic process, and more specifically, charging by measuring the surface potential of a photoconductor at a plurality of points. The present invention relates to an image forming apparatus that detects the amount of dirt on a wire and controls a charge eliminating unit and a cleaning unit based on the amount of dirt to stabilize image quality.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, a potential characteristic on the surface of a photosensitive member partially changes due to a foreign substance such as toner or paper powder that adheres to a charger wire surface over time, which may cause an abnormal image such as uneven density. Had occurred. For this reason, the charge wires are cleaned by an operator or a service person at the time of maintenance for every certain number of sheets.
Further, in order to solve such troublesomeness of the cleaning work, for example, in an "electronic copying machine" disclosed in Japanese Patent Laid-Open No. 1-142742, a predetermined number of copies is counted and the count value is reached. At that time, the cleaning devices provided in the charging charger and the discharge lamp were activated to automatically perform the cleaning.

[0003]

However, the conventional image forming apparatus as described above and Japanese Patent Laid-Open No. 1-14 have been disclosed.
In the "electronic copying machine" disclosed in Japanese Patent No. 2742, the treatment is executed irrespective of the surface potential characteristics of the photoconductor, so that it may not be possible to take appropriate measures. For example, when the toner adheres to the charge wire or the charge eliminating lamp due to the toner scattering from the developing device or the cleaner in the apparatus during the periodic maintenance or when the number of sheets is less than the predetermined number, the measures to be taken are There is a problem that it is not executed at an appropriate timing, a uniform surface potential of the photosensitive member cannot be obtained, and as a result, an abnormal image occurs.

The present invention has been made in view of the above, and detects the amount of dirt on the charge wire for destaticization processing, and automatically executes correction or treatment based on the amount of dirt to determine the image quality. The purpose is to stabilize.

[0005]

In order to achieve the above-mentioned object, the present invention arranges a potential detecting means for detecting a surface potential of a photosensitive member in the main scanning direction and a light emitting member in the main scanning direction of a photosensitive band. Charge eliminating means, and control means for averaging the surface potential data at a plurality of positions of the photoconductor detected by the potential detecting means, and determining the amount of decrease in the average value of the section as the amount of contamination of the charging means. And an image forming apparatus for controlling the supply voltage to the static elimination unit for the corresponding section based on the amount of dirt determined by the control unit.

Further, it is desirable that the control of the voltage supplied to the static eliminating means is executed when the power of the apparatus main body is turned on.

Further, potential detecting means for detecting the surface potential of the photoconductor in the main scanning direction, and potential data storing means for storing initial surface potential data at a plurality of locations of the photoconductor detected by the potential detecting means. And a control means for comparing the potential data stored in the potential data storage means with the potential data detected by the potential detection means after a lapse of a predetermined time, and determining the result as the contamination amount of the charging means. An image forming apparatus is provided.

Further, potential detecting means for detecting the surface potential of the photoconductor in the main scanning direction, and potential data storing means for storing initial surface potential data at a plurality of positions of the photoconductor detected by the potential detecting means. And a control means for comparing the potential data stored in the potential data storage means with the potential data measured by the potential detection means after a lapse of a predetermined time, and judging the result as the contamination amount of the charging means; An image forming apparatus is provided which has a cleaning unit for cleaning the cleaning unit, and controls the cleaning unit when the control unit determines that the charging unit is contaminated.

Further, when the determined dirt amount is outside the preset reference value, it is desirable that the control means suggest the fact to the display means.

[0010]

In the image forming apparatus according to the present invention, the surface potential data at a plurality of locations in the main scanning direction of the photosensitive member are averaged in a section, and a decrease amount of the average value in a certain section with respect to the average value is used as the amount of dirt on the charging member. To detect. Then, the supply voltage to the light emitting member of the static elimination means corresponding to the detected section is
Control based on the detection result.

Further, the image forming apparatus according to the present invention stores the surface potential data at a plurality of locations in the main scanning direction of the photoconductor, and stores the plurality of stored potential data and the potential data measured after a lapse of a predetermined time. And the result is detected as the amount of dirt on the charging member.

Further, in the above, when dirt on the charging member is detected, the charge wire cleaning means is automatically driven to remove dirt on the charge wire.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of an image forming apparatus according to the present invention. Reference numeral 101 denotes a photoconductor drum that forms an electrostatic latent image by an electrophotographic process, and a charge wire 102a made of a thin metal wire such as a tungsten wire to which a high voltage is applied is provided around the photoconductor drum 10.
1. A surface of the photosensitive drum 101 is stretched in the main scanning direction by a charging charger 102 that charges the surface of the photosensitive drum 101 by a corotron method prior to the exposure process, and image light from an optical system (not shown). And an exposure slit 103 provided for exposing the toner, and toner is attached (developed) to the electrostatic latent image on the photoconductor drum 101 formed by the exposure processing by the magnetic brush roller 104a.
Developing unit 104 and the photosensitive drum 1 on the recording paper surface.
A transfer charger 105 for transferring the toner image on 01,
A separation charger 106 that electrically separates the recording paper that is in close contact with the photosensitive drum 101 during the transfer process is arranged.

Further, a fur brush 107a and a cleaning blade 107b are provided on the peripheral surface of the photosensitive drum 101.
And a cleaning unit 10 for collecting the toner remaining on the photoconductor drum 101 after the transfer process.
7, and a quenching lamp (QL) 108 (hereinafter referred to as QL) that initializes the residual potential on the surface of the photosensitive drum 101 after cleaning processing to zero by irradiation light from the fluorescent tube,
An eraser 109 that erases charges outside the required area by the irradiation light of the LED after the charging process, and a pre-transfer process that further uniformizes the charge amount of the toner image formed on the photosensitive drum 101 before the transfer process to improve the transfer efficiency. The charger 110, the potential sensor 111 that is disposed so as to face the surface of the photosensitive drum 101 in the main scanning direction, reads the surface potential, and feeds it back to the control unit 300 (see FIG. 3), and the toner image before the transfer process. A pre-transfer lamp (P that improves the transfer performance by lowering the surface potential of the photosensitive drum 101 by the light of the fluorescent tube).
TL) 112 is arranged as shown. Also, 11
3 is arranged in parallel with the photosensitive drum 101, so as to match the tip of the toner image formed on the photosensitive drum 101,
A registration roller that conveys a recording sheet at a predetermined timing.

With the above arrangement, the basic operation of the present embodiment will be described by taking the case of performing copying processing by a copying machine as an example. First, a series of copying processes is started by depressing a print start key of an operation unit (not shown) arranged on the upper part of the copying machine. The original document to be copied is illuminated by an optical system (not shown). Reflected light obtained by illuminating the document is projected (exposed) on the surface of the photosensitive drum 101 by a lens and a mirror (not shown). When the reflected light corresponding to the image of the original is projected on the surface of the photosensitive drum 101, the electric charge in the projected portion is erased by the intensity of the reflected light, and an electrostatic latent image is formed. For the electrostatic latent image, the developing unit 104
The magnetic brush roller 104a executes the developing process (toner attaching process by the developing process), and a toner image is formed on the photosensitive drum 101.

Further, the recording paper conveyed by the paper feeding / conveying unit (not shown) is adjusted in timing so that the recording paper is aligned with the leading end of the toner image formed on the photosensitive drum 101 by the registration roller 113. Be transported to.

The transfer charger 105 applies the photosensitive drum 1 to the recording paper conveyed by the registration rollers 113.
The toner image formed on No. 01 is transferred. After that, the recording paper on which the transfer processing has been completed is separated from the photoconductor drum 101 by the separation charger 106, and subsequently sent to a fixing unit (not shown) to be subjected to the fixing processing, and then discharged to the outside of the machine. A series of processing ends.

Further, the photosensitive drum 101 after the transfer processing
The residual toner is removed by the cleaning unit 107. Further, the photoconductor drum 101 is initialized by erasing the residual charges by the QL 108. After that, it stands by until the next image processing command is issued.

FIG. 2 is an explanatory view showing a portion of the potential sensor 111 according to the present invention. In the figure, the photosensitive drum 10
With respect to 1, the potential sensor 111 is moved from the A position to the B position. When the potential sensor 111 moves, the photosensitive drum 1
The surface potential of 01 is detected at multiple points.

The potential sensors 111 are arranged in an array, and the potential sensors 111 are arranged in the main scanning direction of the photosensitive drum 101 and in parallel, and the surface potentials at a plurality of points are similarly detected. It may be configured.

FIG. 3 is a block diagram showing a control system of an embodiment according to the present invention. In the figure, a control unit 300 includes a CPU (microcomputer) 301 that executes a control program for the image forming unit, a ROM 302 that stores programs for executing various control processes, and a CP.
RA for storing results and data processed by U301
An input interface 30 for inputting measurement data of a potential sensor 111 and a control element such as M303 to the CPU 301.
4 and an output interface 305 which processes the control signal from the CPU 301. Also, 30
Reference numeral 6 denotes a drive motor that serves as a drive source for moving the potential sensor 111 in parallel with the photosensitive drum 101 in the main scanning direction, and is connected to a motor driver 307 that drives and controls the drive motor 306 based on a control signal from the CPU 301. Has been done. Further, 308 is a power pack (P / P) that supplies a high voltage to the charger 102, and 309 is a power pack (P / P) that supplies a high voltage to the photosensitive drum 101 when measuring the potential of the photosensitive drum 101. Is. Reference numeral 310 indicates the output (light emission amount) of the QL 108 from the control unit 30.
It is a voltage control means for controlling based on the output signal from 0.

FIG. 4 is a graph showing an example of potential measurement in the above embodiment, showing the state of dirt detection on the charge wire 102a of the charger 102. First, after charging the photosensitive drum 101, the potential sensor 111 is moved from the position A to the position B, and the surface potential of the photosensitive drum 101 is detected at a plurality of points (1, 2, 3, ... N). The solid line a (potential after charging) is obtained by taking in the obtained surface potential value. Then, the area from the A position to the B position is divided into n sections (for example, the number of light emitting members forming the QL 108), and the average value (dotted line b) of the measured values in the section is obtained. The difference between the solid line a and the dotted line b is determined by the charge wire 102.
By judging it as a change in characteristics due to dirt on a,
The amount of dirt c is detected.

The contamination detection processing of the charge wire 102a is executed by the control system shown in FIG. That is, CPU3
The control unit 300 having 01 as the core controls the photosensitive drum 10
The post-charging potential a at a plurality of positions in the main scanning direction with respect to one surface is compared with the section average b to obtain the contamination amount c. Then, the voltage control unit 310 controls the amount of charge removal light corresponding to the amount of dirt c based on the control signal from the control unit 300, and QL
Supply to 108. Thereby, the photosensitive drum 101
The surface is the potential d at the corresponding position after the static elimination processing by QL108.
Rises, the fluctuation range of the charging potential in the main scanning direction becomes small, and the charging potential unevenness due to the contamination of the charge wire 102a can be eliminated. Note that the above-mentioned correction due to the contamination of the charge wire 102a is automatically executed when the power source of the apparatus main body is turned on.

Next, another embodiment of the present invention will be described. FIG. 5 is a block diagram showing the control system thereof. The same parts as those shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. In the figure, 501 is a cleaning pad control means for driving and controlling the charge wire cleaning means 502, and 502 is a DC motor 60 built in each charger.
5 (see FIG. 6), the cleaning pad 601 (see FIG.
503 is a charge wire cleaning means for moving the charge transfer device, 503 is a charge removal charger for performing charge removal processing of the pre-transfer charger 110 and the like, and 504 is an operation panel for performing various operations and displaying the state of the device. It is located in.

Further, the charge wire cleaning means 502
Is configured as follows. FIG. 6 is an explanatory view showing a charge wire cleaning mechanism according to the present invention. Here, the charge wire 102a in the charger 102 is shown.
The cleaning mechanism will be described as an example. In the figure, a cleaning pad 601 configured such that a cleaning member such as a felt material is held and slid on the charge wire 102a.
The drive wire 602 is attached to the
Is wound around the drive pulley 603, and further, the DC motor 60 serving as a drive source and the gear portion of the drive pulley 603.
The worm gear 604 fixed to the output shaft of No. 5 is engaged. A home position detector 606 uses, for example, a photo interrupter to detect the home position of the cleaning pad 601.

An example of the operation of the charge wire cleaning mechanism constructed as above will be described with reference to FIGS. Normally, the cleaning pad 601 is the drive wire 60.
It is wound around the drive pulley 603 in a state of being stretched on 2, and is located at the home position. In this state, the control unit 30
Cleaning pad control means 5 according to a control signal from 0
01 turns on the DC motor 605. DC motor 60
When 5 is turned on, the drive pulley 603 is rotated by the worm gear 604, and the cleaning pad 601 slides while holding the charge wire 102a in between. Remove foreign matter. Further, although the cleaning mechanism of the charge wire 102a of the charging charger 102 has been described above, the cleaning mechanism of the charge removing charger 503 is also configured in the same manner and performs the same operation.

FIG. 7 is a graph showing the measured potential of the above embodiment. FIG. 7 (a) is a graph showing the potential unevenness after the charging process and the static elimination process, and FIG. 7 (b) is the surface potential measured after the charging process and the static elimination process at the initial stage and after the elapse (after a predetermined time). The average value of each is shown. In order to detect the charging unevenness of the charging charger 102, after the surface of the photosensitive drum 101 is charged by the charging charger 102,
The potential sensor 111 arranged as described above is moved from the A position to the B position, the surface potential value obtained by detecting the surface potential of the photosensitive drum 101 at a plurality of points is taken into the control unit 300, and fluctuations during that period are taken. get the amount V _max -V _min. That is, this variation amount V _max −V _min results in uneven charging. To obtain the potential unevenness on the surface of the photoconductor drum 101 after the charge removal, the surface of the photoconductor drum 101 is charged by the charging charger 102, and then the charge removal charger 503 is used.
After the static elimination process is performed by the electric potential sensor 111, the potential sensor 111 is moved from the position A to the position B in the same manner as described above.
Captures the surface potential values obtained surface potential of 01 is detected by a plurality of points, obtaining therebetween variation V _max -V _min.
That is, this variation amount V _max −V _min becomes the static elimination unevenness.

To detect the dirt on the charge wire 102a mounted on the charger 102, the surface of the photosensitive drum 101 is charged by the charger 102, and then the potential sensor 111 is moved from position A to position B. Then, the measured values are taken in multiple times during that period to obtain the initial value (a), and the value or its average value (Va) is RA.
Store in M303. The same measurement is performed again after the elapse of a preset time, and the value (b) after the elapse of a certain time is obtained. Here, the initial value (V
a) and the value (Vb) over time are compared (Va-Vb) by the CPU 301 to obtain the potential difference corresponding to the contamination of the charge wire 102a.

As described above, the charge wire 102 is determined by the difference between the initial value of the surface potential of the photosensitive drum 101 and the elapsed value.
The dirt amount of a is detected. Based on the detection of the amount of dirt, the controller 300 outputs a control signal to the cleaning pad controller 501, operates the charge wire cleaner 502, and cleans the charge wire 102a as described above. Eliminate insufficient charge.

Further, when the measured value of the non-uniform charging of the charger 102 or the charger 503 or the stain caused by each wire is equal to or larger than a preset reference value, the reference value is set after the automatic cleaning of the wire. If it does not recover, the message such as "Serviceman call-charger error ..." Is displayed on the operation panel 504. By this instruction, the subsequent treatment (maintenance processing by the service person) is executed promptly, and the surface potential that greatly affects the image quality can be maintained and stabilized.

In the present embodiment, an example of a copying machine was described as an image forming apparatus, but the present invention is not limited to this, and is directly applied to a facsimile machine or a laser printer using an electrophotographic process. can do.

[0032]

As described above, according to the image forming apparatus of the present invention, the surface potential data at a plurality of locations in the main scanning direction of the photosensitive member are averaged in a section, and the average value of a certain section with respect to the average value. Is detected as the amount of dirt on the charging member. Then, since the voltage supplied to the light emitting member of the charge eliminating means corresponding to the detected section portion is controlled based on the detection result, it is possible to eliminate potential fluctuation due to dirt on the charge wire and secure stable image quality. it can.

Further, the surface potential data at a plurality of positions in the main scanning direction of the photoconductor are stored, and the stored plurality of potential data are compared with the potential data measured after a predetermined time has passed, and the result is compared. Is detected as the amount of dirt on the charging member, and the charge wire cleaning means is automatically driven to remove the dirt on the charge wire. Therefore, the reliability of the charger system can be improved and the image can be stabilized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing the operation of the potential sensor according to the present invention.

FIG. 3 is a block diagram showing a control system of the image forming apparatus according to the present invention.

FIG. 4 is a graph showing an example of potential measurement of the embodiment shown in FIG.

FIG. 5 is a block diagram showing another control system of the image forming apparatus according to the present invention.

FIG. 6 is an explanatory view showing a cleaning mechanism of the charge wire according to the present invention.

FIG. 7 is a graph showing measured potentials of the example shown in FIG.

[Explanation of symbols]

101 Photoreceptor Drum 102a Charge Wire 108 QL 111 Potential Sensor 301 CPU 302 RO
M 303 RAM 310 Voltage control means 501 Cleaning pad control means 502 Charge wire cleaning means 503 Static elimination charger 504 Operation panel

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Tatsuo Hirono 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Issei Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo In stock company Ricoh (72) Inventor Makoto Osaki 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh stock company (72) Inventor Tetsuro Miura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh company (72) Inventor Kazunori Sakauchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) In-house Masato Yanagita 1-3-3 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (5)

[Claims] 1. A plurality of potential detecting means for detecting a surface potential of a photoconductor in the main scanning direction, a destaticizing means in which light emitting members are arranged in the main scanning direction of a photosensitive band, and a plurality of photoconductors detected by the potential detecting means. And a control unit for averaging the surface potential data at the points and determining the amount of decrease in the average value of the section with respect to the average value as the amount of contamination of the charging unit. An image forming apparatus, characterized in that the voltage supplied to the static eliminating means is controlled for each section. 2. The image forming apparatus according to claim 1, wherein the control of the voltage supplied to the charge eliminating unit is executed when the power of the apparatus main body is turned on. 3. A potential detecting means for detecting a surface potential of the photoconductor in the main scanning direction, and a potential data storing means for storing initial surface potential data at a plurality of positions of the photoconductor detected by the potential detecting means. And a control means for comparing the potential data stored in the potential data storage means with the potential data detected by the potential detection means after a lapse of a predetermined time, and determining the result as the contamination amount of the charging means. An image forming apparatus characterized by the above. 4. A potential detecting means for detecting a surface potential of the photoconductor in the main scanning direction, and a potential data storing means for storing initial surface potential data at a plurality of positions of the photoconductor detected by the potential detecting means. And a control unit that compares the potential data stored in the potential data storage unit with the potential data measured by the potential detection unit after a lapse of a predetermined time, and determines the result as the contamination amount of the charging unit.
Cleaning means for cleaning the charging means, and when the control means determines that the charging means is contaminated,
An image forming apparatus characterized by controlling the cleaning means. 5. The image forming apparatus according to claim 3, wherein the control unit indicates to the display unit when the determined dirt amount is outside the preset reference value. .