JP2003091145A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge wire cleaning device capable of detecting the present position of a cleaning pad and controlling the movement of the pad to a home position with high accuracy and a simple constitution only by detecting the current of a motor for driving the cleaning device without installing a home position detecting means, besides, capable of shortening a cleaning time, as for the charge wire cleaning device equipped with the cleaning pad for cleaning a charge wire while moving backward and forward from one end of the charge wire to the other end. SOLUTION: In the image forming device provided with the charge wire cleaning device 1 for cleaning the charge wire by driving the motor 16 forward and backward, and moving the cleaning pad 11 supported by a reciprocating moving body 12 backward and forward along the charge wire 8, in the case a counted value counted by a means for counting the number of sheets reaches a prescribed set value in the midst of an image forming operation, the image forming operation by the image forming apparatus is stopped, and the charge wire is cleaned by driving the reciprocating moving body in both directions, or one direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, etc., and more particularly, to a charge wire used for a corona discharge type charger automatically installed in the image forming apparatus. The present invention relates to an image forming apparatus including a charge wire cleaning device for cleaning.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a corona discharge type charger used for charging a photosensitive member as an image carrier is in an environment where it is easily contaminated by developer dust. In particular, when the charge wires whose both ends are stretched and supported by the blocks respectively provided at the front and rear positions of the charger are contaminated by the adhesion of toner or the like, their discharge characteristics are changed and the image forming conditions are changed. Will not be obtained. For example, JP-A-7-261520 and JP-A-7-261520
No. 28311, JP-A-6-214450 and the like disclose various methods for properly cleaning the charge wire even under various circumstances. However, all of them are cleaning pads that reciprocate along the charge wire. Control of charger cleaning using a position detection sensor that detects the current position of the cleaning pad, such as the home position and offset position, in order to detect whether or not the movement operation of the It has a configuration for performing. However, when the position detection sensor is used, there is a drawback that the cost is increased by the position detection sensor and the control method is complicated. For this reason, without using the position detection sensor as much as possible,
The development of a device and method for detecting the current position of a cleaning pad has long been awaited. Further, there are problems that the control for returning the cleaning pad to each fixed position on both ends of the charge wire is complicated, and that the time required for cleaning is prolonged, and there is a need for improvement in this respect as well.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and the pressure wire of the charge wire for corona discharge is moved by reciprocating from one end to the other end of the charge wire. In a charge wire cleaning device equipped with a cleaning pad for cleaning,
Detecting the current position of the cleaning pad and controlling the movement to the fixed position only by detecting the electric current of the motor that drives the cleaning device without disposing the fixed position detection means at both ends of the charge wire, With a simple and accurate structure,
Another object of the present invention is to provide an image forming apparatus provided with a charge wire cleaning device that shortens the cleaning time.

[0004]

In order to solve the above-mentioned problems, the invention of claim 1 is a cleaning pad for press-contacting an image carrier with a charge wire for corona discharge charging,
A reciprocating body that supports the cleaning pad, a transfer body that reciprocates the reciprocating body in parallel with the charge wire, and a stopper for the reciprocating body that is provided at both ends of the charge wire in the axial direction. A motor that drives the transfer body, and a detection unit that detects a locked state by a detection current that changes according to output torque when the motor is driven,
A control means for controlling the drive of the motor, and by driving the motor in forward and reverse rotations, the cleaning pad supported by the reciprocating body is reciprocally moved along the charge wire. In the image forming apparatus that performs the cleaning operation, the control unit includes a number counting unit that counts the number of output sheets for each image forming operation, and a non-volatile storage unit that stores the count value of the number counting unit. If the count value of the number counting means reaches a preset value during the image forming operation, the image forming operation by the image forming apparatus is stopped and the reciprocating body is driven in both directions or in one direction to charge. The feature is that the wire is cleaned. The invention of claim 2 is
The cleaning operation mode by the cleaning pad supported by the reciprocating body can be selected from two modes, a cleaning mode by bidirectional movement of the reciprocating body and a cleaning mode by unidirectional movement. Claim 3
In the invention, the position and direction of the reciprocating moving body when the cleaning operation is finally stopped are stored in a non-volatile storage means,
When the power of the image forming apparatus is turned on again, a home position returning operation for returning the reciprocating moving body toward the last stopped position is performed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. 1A and 1B are a schematic front view and a cross-sectional view (schematic) taken along the line AA of the charge wire cleaning device according to the embodiment of the present invention.
This charge wire cleaning device 1 is attached to a corona discharge type charger (charger device) 2 for preliminarily uniformly charging the surface of a photoconductor as an image carrier in an electrophotographic process in an electrophotographic image forming apparatus. And used. The cleaning device 1 can also be applied to cleaning wires of a corona discharge type transfer charger,
Here, the cleaning of the charge wire used for the charger will be described as an example. First, the charger 2 has an outer casing 5
(Omitted in FIG. 1A), front end blocks (stoppers) 6 respectively arranged at the front and rear ends of the casing 5, rear end blocks (stoppers) 7, both end blocks 6, 7 The charging wire 8 has both ends locked and stretched, and a power supply (not shown) for supplying the charging wire 8 with a voltage for discharging. The charge wire 8 is arranged so as to face the surface of the photoconductor (not shown). The charge wire cleaning device 1 includes a cleaning pad 11 that is in pressure contact with the charge wire 8.
And a slider 12, which is a reciprocating body that supports the cleaning pad 11 at the lower part, and axially rotatably supported by bearings provided at the end blocks 6 and 7, respectively, and penetrates the slider 12. It is fixed to one end of the feed screw rod 13 and a feed screw rod (transport body) 13 that drives the slider 12 to move back and forth in the axial direction (direction parallel to the charge wire) by being screwed into the formed female screw portion. The driven gear 14 and the drive gear 1 that meshes with the driven gear 14.
5 and a motor 16 that rotationally drives the drive gear 15. In addition, each end block 6 and 7 includes a slider 12
Functions as a stopper that stops the front side and the rear side respectively. Further, as will be described later, the charge wire cleaning device 1 includes a detection unit that detects a locked state by a detection current that changes according to the output torque when the motor is driven, and a control unit that controls the driving of the motor. . The slider 12 has a rotatable feed screw rod 13 screwed into the female screw portion thereof, and the feed screw rod 13 is normally and reversely rotated by a driving force from a motor 16 so that the slider 1
2 reciprocates along the feed screw rod 13. The slider 1 that was originally in the home position (front side) shown in the figure
When 2 is sent to the rear side by the rotation of the feed screw rod 13, the slider 12 moves along a stable path while being guided by a guide member (not shown) provided on the charger 2 side,
The cleaning pad 11 moves while sandwiching the charge wire 8. By reciprocating the cleaning pad 11 in this state, the charge wire 8 is cleaned. The feed screw rod 13 is normally and reversely rotated by driving the end driven gear 14 of the feed screw rod 13 by the drive gear 15 mounted on the output shaft of the motor 16, that is, by the forward and reverse rotation of the motor 16.

FIG. 2 is a block diagram of a control system according to an embodiment of the present invention. The control means 30 is connected to the host computer 33, the motor drive circuit 37, the current detection circuit 38, and the like. The control unit 30 is C of the image forming apparatus in which the charge wire cleaning device 1 of the present embodiment is mounted.
PU 31, host computer 3 in image forming apparatus
A controller 32 that performs intermediary I / F and image data reception and transmission among the three, a ROM 34 that is a read-only memory that stores a control program of the image forming apparatus,
RAM 35, which is a readable / writable memory used in the control program, and EE, which is a non-volatile memory that can retain data even when the power of the image forming apparatus is turned off.
The PROM 36, the motor drive circuit 37 that drives the motor 16, the current change in the motor drive circuit 37 is detected, and the information is detected as a motor lock state (High).
A current detection circuit 38 for converting into a lock signal of an output or a motor drive state (Low) output is provided. Also, C
The PU 31 includes a timer 39 for measuring the movement time of the slider 12 in the present embodiment, and controls the timer 39. Further, the control unit 30 includes, for example, in the CPU 31, a number counting unit that counts the number of output sheets for each image forming operation by an image forming unit (not shown). The current detection circuit 38 functions as a detection unit that detects the locked state by the detection current that changes according to the output torque when the motor is driven. One of the characteristic configurations of the present invention is that the control unit 30 stores a number counting unit that counts the number of output sheets for each image forming operation by an image forming unit (not shown), and a count value by the number counting unit. When the count value of the sheet number counting means reaches a preset value during the image forming operation, the image forming operation is stopped and the reciprocating moving body is moved in both directions or one side. In this configuration, the charge wire is cleaned by driving in the direction.

FIG. 3 is a flow chart showing the timing when activating the charger cleaning in the embodiment of the present invention. The CPU 31 maintains the maintenance counter n of the EEPROM 36 each time one image is formed, that is, every time a print command is received from the controller 32 (S1).
Is incremented (S2). Then, whether or not the value of the maintenance counter n has reached the cleaning time (the number of output sheets corresponding to the cleaning time) Np of the charge wire 8 set in the ROM 34 in advance is monitored every time one sheet is printed (S
3) If the cleaning time Np has been reached (S3, Ye
s), interrupt the JOB where the print command is currently coming,
A cleaning request for the CPU 31 charge wire 8 is sent (S5, S6), and the charge wire is cleaned. When the controller 32 receives the request command, it notifies the host computer 33 that the printer is busy and stops receiving the image data. When the cleaning of the charge wire is completed, the counting by the number counting means is performed again (S2). When Step 3 is No, that is, when the cleaning time Np has not been reached,
If the print command is not completed in step 4, the monitoring from step 2 onward is performed.

Next, with reference to the flow charts of FIGS. 4 and 5, the cleaning operation of the forward and return paths of the charge wire and the control at the time of abnormality in this embodiment will be described. First, in the homeward cleaning operation of FIG.
When the start command is received from the motor drive circuit 37, a normal rotation drive signal for driving the motor 16 in the normal rotation is output to the motor drive circuit 37, and the motor 16 is driven in the normal rotation (S11). As a result, the slider 12 is moved to the front end block 6
From the front home position in contact with the rear end block 7 toward the rear end block 7 (rear home position), whereby the cleaning pad 11 slides while pressingly contacting the charge wire 8. Perform cleaning. The CPU 31 starts the timer 39 from the time when the rotation drive of the motor 16 is started (S
12), the time T0 is measured until the motor 16 enters the locked state (High output) (S13). That is, when the slider 12 reaches the rear end block 7 and cannot move any more, the motor 16 is locked. Therefore, the current of the motor drive circuit 37 changed by the torque of the motor 16 at this time is detected by the current detection circuit 38. The detected voltage is output to the CPU 31 as a lock signal (High output). In step 3, C
When the PU 31 receives the lock signal from the current detection circuit 38, it is determined that the slider 12 has reached the rear end block 7, and the CPU 31 temporarily stops the output of the motor 16 to clean the return path ( S14). At this time, it is determined that the current position of the slider 12 is on the rear side in the EEPROM.
It is stored in 36. Further, in the case where Step 13 is No, that is, when the lock signal is not detected and the moving time T0 of the slider 12 measured by the timer 39 has exceeded the set time T1 (30 seconds in this embodiment). (S15), for example, the normal rotation drive signal to the motor 16 is not normally transmitted, or the charge wire 8
Is highly contaminated and the cleaning pad 11 is caught on the dirt of the charge wire 8 and the transfer speed of the slider 12 is slowed down. ) To finish.

On the other hand, in the returning path cleaning operation, as shown in the flowchart of FIG. 5, the CPU 31 causes the motor drive circuit 37 to output a reverse rotation drive signal for driving the motor 16 in reverse rotation, whereby the motor 16 is driven in reverse. (S18), the slider 12 moves from the position in contact with the rear end block 7 toward the front end block 6 (front direction), so that the cleaning pad 11 cleans the charge wire 8. CPU
The timer 31 starts the timer 39 from the time when the reverse rotation driving of the motor 16 is started (S19), and measures the time T0 until the motor 16 enters the locked state (High output) (S20). In step 20, when the CPU 31 receives the lock signal from the current detection circuit 38,
It is determined that the slider 12 has reached the front end block 6 and stopped, and the output of the motor 16 is stopped (S2).
1). At this time, the fact that the current position of the slider 12 is on the front side is stored in the EEPROM 36. And
When the measured time of the timer 39 started from the time when the CPU 31 starts the reverse rotation driving of the motor 16 is not within 4 seconds (S24), it is determined as normal end, the cleaning operation is ended, and the controller 32 is ready to print. Is sent. Here, the measurement time T of the timer 39
When 0 is within 4 seconds which is shorter than the set time T1 (S14), for example, when the cleaning pad 11 is caught by the dirt of the charge wire 8 and stopped, and the lock signal becomes High from the beginning, Since there is a high possibility that the moving operation of the slider 12 is abnormal, abnormal processing (S25) is performed and the processing ends. Further, when the lock signal is not detected in step 20, and the timer 3
When the moving time T0 of the slider 12 measured by 9 has passed the set time T1 (S22), the slider 12
Since the moving operation of is abnormal, an abnormal process (S23) is performed and the process ends. The abnormality processing is performed after the abnormality (S17, S23, S25) that occurred during the charger cleaning operation processing
The cleaning operation is stopped to make the image forming apparatus unusable. In addition, the controller 31 is notified of the error content,
A message is displayed on the display as shown in FIG. 8 to prompt the user to call a maintenance person.

Next, a second characteristic structure of the present invention is that the cleaning operation mode by the cleaning pad 11 supported by the slider (reciprocating movable body) 12 is changed to the cleaning mode by the slider 12 moving in both directions, and the one-way cleaning mode. The point is that the cleaning mode by movement can be selected from two modes. That is, FIG. 6 is a flowchart showing a control procedure for enabling selection of the cleaning operation mode. This cleaning mode selection can be set from a display panel or the like by an operation by a user or a maintenance person (service person). If, for example, "0" is set in step 31, the "bidirectional cleaning operation" mode is set (S32),
After the specified number of sheets have been printed, the printing is interrupted, and the cleaning operation for the return path is continuously performed after the cleaning operation for the outward path. Normally, this mode is set as the default, but for reasons such as not wanting to wait during printing, step 31
When "1" is set in, "One-way cleaning operation"
The mode is set (S33), the printing is interrupted after the specified number of prints, and the forward pass or the backward pass is alternately performed, so that the cleaning time can be shortened once, and the operation rate of the image forming apparatus can be increased. it can. As described above, according to this embodiment, the cleaning operation mode can be selected from the two modes of the bidirectional cleaning of the reciprocating body and the one-way cleaning. When (time reduction) is emphasized, it is possible to select a setting according to the user's device usage status such as one-way cleaning.

Next, in the third characteristic configuration of the present invention, the position and direction of the slider 12 when the cleaning operation is finally stopped are stored in the non-volatile storage means 36, and the power supply of the image forming apparatus is turned on. Is to perform a home position returning operation for returning the slider 12 toward the last stopped position when it is turned on again. That is, conventionally, generally, as a preliminary operation for locating the movement start position of the slider 12 at the start of cleaning to the home position of either the rear or the front, or when the slider 12 is in the middle of the charge wire 8 during image formation. In order to prevent the occurrence of charging failure due to the position of the slider 12, the motor 16 is driven in the forward direction or the reverse direction as an initial operation to return the slider 12 to either the front or rear home position. In this embodiment, the charger 2 is attached to the image forming apparatus (the setting operation is performed).
For example, when the cleaning operation is interrupted during the cleaning operation by the charge wire cleaning device 1, or when the power of the image forming apparatus is turned on or the cover of the image forming apparatus is opened or closed.
The slider 12 is being returned. That is, in such a case, since the slider 12 may be stopped at a halfway position, it is necessary to return to one of the home positions.

Further, in the "one-way cleaning operation" mode shown in FIG. 6, the home position returning operation is performed at the front side home position or the rear side even when the home position is abnormal (the slider 12 is at a halfway position). You can return to either home position. However, considering the normal state (cleaning is normally performed and the position is also normal), the slider 12 is already located at either the front home position or the rear home position. The home position is returned as a confirmation operation. Therefore, by performing the returning operation after recognizing which home position the vehicle is currently located in, it is possible to reduce unnecessary operation and shorten the time required for returning.
As described above, the CPU 31 determines which stop position the slider 12 is in during the cleaning operation.
It is stored in the EPROM 36 (FIG. 4, S14, FIG. 5, S21). As shown in FIG. 7, when the stored current stop position information (S41) is the front end block position, the motor 16 is driven to rotate in the reverse direction to move the slider 12 toward the front side. Causes the return path cleaning operation to be performed. When it is at the rear end block position, the forward cleaning operation of moving the slider 12 toward the rear side is performed by driving the motor 16 to rotate in the forward direction. By this operation, the CPU 31 returns the slider 12 to the home position and confirms it. In this way, by performing the return operation after recognizing which home position the vehicle is in, it is possible to reduce unnecessary operation and shorten the time required for the return.

[0013]

As described above, according to the present invention, there is provided a cleaning pad for cleaning the charge wire by reciprocating between one end and the other end of the wire while pressing the charge wire for corona discharge. In the charge wire cleaning device, the fixed position detecting means is not arranged at both end positions of the charge wire, and the current of the cleaning pad is detected and the fixed position is detected only by detecting the electric current of the motor driving the cleaning device. It is possible to provide a charge wire cleaning device in which control for movement is performed with high accuracy and a simple configuration, and the cleaning time is further shortened. According to the first aspect of the present invention, the charge wires are cleaned every time the number of image-formed sheets reaches a certain number, so that the stains on the charge wires are eliminated and stable image quality is obtained. Normally, the reciprocating moving body is reciprocated to clean the charge wire, but it is possible to shorten the time by dividing and cleaning the charge wire in each direction. According to the second aspect of the present invention, the cleaning operation mode can be selected from the two modes of the bidirectional cleaning of the reciprocating moving body and the one-way cleaning. For example, when image quality is important, bidirectional cleaning, speed (time reduction) When) is emphasized, it is possible to select a setting according to the user's device usage status such as one-way cleaning.

According to the third aspect of the invention, the position and direction of the slider when the cleaning operation is finally stopped are stored in the non-volatile storage means, and the slider is moved when the power of the image forming apparatus is turned on again. A home position returning operation for returning to the last stopped position is performed. That is, the home position return operation of the slider is a preliminary operation for always starting the starting position of the cleaning operation from the home position, or for the purpose of preventing the cleaning unit from being stopped at an intermediate position by mistake during image formation. Done. Therefore, by performing this operation each time the power is turned on and the cover is opened and closed,
It is possible to improve the accuracy of the abnormality detection for the malfunction of the motor, the disconnection of the unit, etc., and prevent the abnormality of the output image. In the "one-way cleaning operation" mode, even if the home position return operation is abnormal (such as when the slider is at a halfway position), it returns to either the front home position or the rear home position. Just do it. However, during normal operation (cleaning is normally performed and the stop position is also normal), the slider is already located at either the front home position or the rear home position, so most of the home operations as confirmation operations are performed. Return to position. Therefore, after confirming which home position you are currently in,
By performing the return operation to each home position, useless operation can be reduced and time can be shortened.

[Brief description of drawings]

1A and 1B are schematic front views showing a configuration of a charge wire cleaning device according to an embodiment of the present invention, and FIG.
-A sectional view.

FIG. 2 is a block diagram of a control system according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a timing when activating charger cleaning in the embodiment of the present invention.

FIG. 4 is a flowchart showing an outward cleaning operation.

FIG. 5 is a flowchart showing a return pass cleaning operation.

FIG. 6 is a flowchart according to an embodiment that enables selection of a cleaning mode.

FIG. 7 is a flowchart showing a home position returning operation.

FIG. 8 is a diagram showing an example of an operation unit.

[Explanation of symbols]

1 Charge Wire Cleaning Device, 2 Charger, 5 Casing, 6 Front End Block, 7 Rear End Block, 8 Charge Wire, 11 Cleaning Pad, 12 Slider, 13 Feed Screw Rod (Transfer), 14 Driven Gear, 15 Drive gear, 16 motor, 30 control means, 32 controller, 33 host computer, 34 ROM, 35 RAM, 36 E
EPROM, 37 motor drive circuit, 38 current detection circuit, 39 timer.

Claims (3)

[Claims] 1. A cleaning pad that presses an image carrier against a charge wire that is charged by a corona discharge method, a reciprocating body that supports the cleaning pad, and a reciprocating body that reciprocates in parallel with the charge wire. For the transfer wire, stoppers for reciprocating moving bodies provided at both ends of the charge wire in the axial direction, a motor for driving the transfer body, and a detection current that changes depending on output torque when the motor is driven And a control means for controlling the drive of the motor, and by driving the motor in forward and reverse rotations,
In an image forming apparatus for performing a cleaning operation of a charge wire by reciprocating a cleaning pad supported by the reciprocating body along a charge wire, the control unit counts the number of output sheets for each image forming operation. If the count value of the number counting means reaches a preset value during the image forming operation, the image forming means has an image forming means, and a non-volatile storage means for storing the count value of the number counting means. An image forming apparatus, wherein an image forming operation by the apparatus is stopped and a reciprocating body is driven in both directions or one direction to perform charge wire cleaning. 2. A cleaning operation mode using the cleaning pad supported by the reciprocating body can be selected from two cleaning modes: a cleaning mode in which the reciprocating body moves in both directions and a cleaning mode in which the reciprocating body moves in one direction. The image forming apparatus according to claim 1. 3. The position and direction of the reciprocating moving body when the cleaning operation is finally stopped are stored in a non-volatile storage means, and the reciprocating moving body is moved when the power of the image forming apparatus is turned on again. The image forming apparatus according to claim 1, further comprising a home position returning operation for returning to the last stopped position.