JPH0450992A - Controller for correcting meandering of belt - Google Patents

Abstract

PURPOSE:To prevent the deterioration of printing quality by driving a belt position detecting means at a prescribed period and providing a processor which calculates the correcting information of a mechanism for correcting the meandering of a belt from the belt position information. CONSTITUTION:The output of the belt position detecting means 16 is read into the processor 17 via an I/O port 18. The processor 17 transmits a control signal via a driver 19 to a cam motor 15 and controls the meandering direction of the transfer belt 5. Namely, the initial correction of the meandering is executed in such a manner that the transfer belt 5 parts form the belt position detecting means 16 while the transfer belt 5 exists in the belt position detecting means 16 and that the transfer belt approaches the belt position detecting means 16 unless the belt exists in the belt position detecting means 16 at the time of turning of a power source. The moving direction and moving speed of the transfer belt 5 are then calculeted from a change in the belt position information and the next correction of the meandering is executed. The printing quality is improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a laser beam printer, and particularly to correction of meandering of a transfer belt thereof.

[Conventional technology]

A method for correcting meandering of a transfer belt in a conventional laser beam printer will be explained with reference to FIGS. 3 and 4.

FIG. 3 is an overall configuration diagram of the laser beam printer. Paper 1 is fed through multiple paper feed hoppers 2 classified by paper size.
A predetermined paper feeding roller 3 is intermittently driven to feed out one sheet at a time.

The fed paper 1 is sequentially conveyed by a conveyance roller 4 and sent to a transfer belt 5. The transfer belt 5 and the photosensitive drum 6 are in contact with each other and rotate at a constant speed, and the surface of the transfer belt 5 is charged by a charging corotron 7 and the surface of the photosensitive drum 6 is charged by a charging corotron 8 to opposite potentials.

The paper 1 fed onto the transfer belt 5 is electrostatically attracted to the transfer belt 5 and sent to the contact portion with the photosensitive drum 6 .

Due to the contact with the photosensitive drum 6, the developed toner image on the photosensitive drum 5 is transferred onto the paper 1.

The paper 1 onto which the toner image has been transferred is sent to the fixing device 9,
The toner image is fixed on the paper 1.

Thereafter, the paper 1 is turned over and returned to the photosensitive drum 6 again if printing on the back side is to be performed, and sent to the stacker 10 when printing on the back side is not to be performed, and the printing operation is completed.

FIG. 4 is a detailed view of the transfer belt 5. The transfer belt 5 moves in the direction of the arrow due to the rotation of the drive roller 11. The drive roller 11 is driven by a belt motor 12. Further, 13 is a driven roller that rotates according to the transfer belt 5 and applies a required tension to the transfer belt 5.

Generally, in the transfer belt 5 drive system, the tension acting in the width direction of the transfer belt 5 is not constant due to non-parallelism between the drive roller 11 and the driven roller 13, uneven thickness of the transfer belt 5, etc. There was a problem that 5 was biased to one side.

For this reason, conventionally, the eccentric cam 14 is driven by the cam motor 15 to change the position of the drive roller 11, and the belt tension distribution is controlled to correct the meandering. Furthermore, the cam motor 15 used is one that can be stopped at any angle, such as a stepping motor.

Furthermore, when the power is turned on, the eccentric cam 14 is set to the initial position.

The transfer belt 5 moves in the six directions of arrows when the cam motor 15 is rotated clockwise, and moves in the direction of arrow B when rotated counterclockwise.

When the transfer belt 5 moves in the six directions of arrows and the first belt position detection means 161 detects the left end of the transfer belt 5, the cam motor 15 is rotated counterclockwise by a predetermined number of steps, and the meandering direction is moved in the direction of arrow B. Change direction. Next, when the transfer belt 5 moves in the direction of arrow B and its right end is detected by the second belt position detection means 162, the cam motor 15 is rotated clockwise by a predetermined number of steps, changing the meandering direction to the direction A. do. The meandering permissible limit positions on the left and right sides are respectively set by the first and second belt position detection means 161 and 162.

By switching the meandering direction as described above, control is performed so that both ends of the belt do not protrude beyond the first and second belt position detection means 161 and 162.

[Problem to be solved by the invention]

In the above-mentioned conventional device, if the amount of eccentricity of the eccentric cam 14 is small, the transfer belt 5 does not necessarily move to a predetermined position due to variations in the assembly accuracy of the drive roller 11, driven roller 13, eccentric cam 14, etc., variations in the thickness of the transfer belt 5, etc. Therefore, the amount of eccentricity of the eccentric cam 14 is set to be large in order to switch the predetermined meandering direction.

As a result, the meandering speed of the transfer belt 5 becomes faster than necessary, resulting in an increase in lateral wobbling of the paper 1 on the transfer belt 5, resulting in a problem of deterioration of print quality.

An object of the present invention is to provide a belt meandering correction control device that reduces the meandering speed of the transfer belt 5 and prevents deterioration of print quality.

[Means for solving the invention]

In the present invention, in order to reduce the number of belt position detection means from two to one and simultaneously achieve the above object, the belt position detection means detects the presence or absence of the transfer belt when the power is turned on, and when the transfer belt is detected, the belt position detection means detects the presence or absence of the transfer belt. In this case, an initial value of correction information for the direction in which the transfer belt moves away from the belt position detection means is set in the belt meandering correction mechanism, and when the transfer belt is not detected, an initial value for correction information for the direction in which the transfer belt approaches the belt position detection means is set. The belt meandering correction mechanism is set, and at the same time, the belt initial position information indicating that the belt position was biased to the left or right side is set, and the information is compared with the next belt position information to determine the next belt meandering correction information. Calculate.

Next, the belt position information within two consecutive predetermined times are sequentially compared to calculate the moving direction and moving speed of the transfer belt, and the next belt meandering correction information is calculated.

When comparing the above belt position information, if the first and second belt position information do not change and are equal to the above belt initial position information, it means that the meandering correction is not working normally, so the electrophotographic printing device Executes abnormality search processing.

Furthermore, if the first belt position information is different from the above-mentioned initial belt position information and the second belt position information becomes equal to the initial belt position information, it means that the belt is biased toward the end position. The belt meandering correction information is reset to the above initial value in the opposite direction.

Further, if the first and second belt position information are different from each other and different from any of the belt initial position information, the belt meandering correction mechanism is driven by the average value of the rightward and leftward belt meandering correction information. I'll do what I do.

[Effect]

When the power is turned on, if the transfer belt is within the belt position detection means, the transfer belt is moved away from the position detection means.
Further, if the transfer belt is not within the belt position detection means, initial meandering correction is performed so that the transfer belt approaches the position detection means.

Next, the moving direction and moving speed of the transfer belt are calculated from the change in the belt position information, and the next belt meandering correction is performed.

At this time, if the above belt position information does not change continuously from the initial value set when the power is turned on, an abnormality search process of the electrophotographic printing device is executed, and if the belt position information changes before and after, the above Correct belt meandering.

In the above-mentioned belt meandering correction, when the transfer belt enters the belt position detecting means and leaves the belt position detecting means, the transfer belt is moved away from the position detecting means, and when the transfer belt leaves the belt position detecting means and the transfer belt leaves the belt position detecting means. In this case, the meandering of the transfer belt is corrected so that it approaches the position detection means.

Further, when the transfer belt is detected or not detected by the belt position detection means, the belt meandering correction is performed so that the time interval between the detection and non-detection becomes even smaller.

〔Example〕

Examples of the present invention are shown in FIGS. 1 and 2 (a) to (d) below.
This is explained by:

FIG. 1 is a block diagram of an embodiment of a transfer belt meandering correction device according to the present invention.

In FIG. 1, the cam motor 15 is a stepping motor that can be stopped arbitrarily. Further, in FIG. 4, two belt position detecting means 161 and 162 are used, but in FIG. 1, for example, one belt position detecting means 1 shown on the left side is used.
Use only 6.

The output of this belt position detection means 16 is from ■/○ port 18.
The processor 17 reads the cam motor 15 via the driver 19.
A control signal is sent to the transfer belt 5 to control the meandering direction of the transfer belt 5.

Further, the memory 20 is coupled to the processor 17 and includes a plurality of storage areas.

The plurality of storage areas of the memory 20 include a processor 17
A belt position information area obtained by monitoring the output of the belt position detecting means 16, an A direction correction information area that stores position information of the cam motor 15 corresponding to the movement of the transfer belt 5 in the A direction, and similar deflection direction correction information. area, and an eccentric cam stop position information area indicating the actual stop position of the cam motor 15.

Furthermore, the belt position information area includes three types of belts corresponding to whether the belt end is within the belt position detecting means 16, is located away from the belt position detecting means 16, or is in the middle of the belt position detecting means 16. Location information is stored.

FIGS. 2(a) to 2(d) are flowcharts showing belt meandering correction control procedures performed by the apparatus of the present invention shown in FIG. 1.

In this flowchart, as an example, the transfer belt 5 makes one revolution in 3 seconds, and the belt position detection signal is taken in 3.00 times in these 3 seconds, that is, at a period of 10IIIs.

In FIG. 2, when the power is turned on in step S1,
In step S2, an initial value (for example, +100) of the direction correction information and an initial value (for example, -100) of the direction correction information is set in the belt correction information storage area of the memory 20.

Next, in step S3, the initial position of the transfer belt 5 is checked, and if the presence or absence of the transfer belt is detected by the belt position detection means 16, the process moves to step S4, and if it is not detected, the process moves to step S6.

In steps S4 and S5 and steps S6 and S7, the memory 2
Initial values of belt position information and eccentric cam stop position information are set in the belt position information area and eccentric cam stop position information area within 0, respectively.

The belt position information Q in steps S4 and 86 is an area that stores the number of transfer belt detections in the past three seconds.

Further, belt position information 1, 2, and 3 are areas for storing the number of transfer belt detections within the first 1 second and the last 1 second of the next 3 seconds, respectively.

If the transfer belt 5 is detected, in step S4 it is assumed that the transfer belt 5 has been continuously detected for the past three seconds, and belt position information 0 is set to 300. Further, in order to judge the movement result of the transfer belt from the number of detections per second in the future, the belt position information 23 is set to 100, and the same is set to 0. Next, since it is necessary to move the transfer belt 5 in the B direction, the initial value of the B direction correction information is set as the eccentric cam stop position information in step S5.

Further, if the transfer belt 5 is not detected, it is assumed that the transfer belt 5 has not been detected for the past 3 seconds, and step S is performed.
In Step 6, the belt position information O is set to 0, and all of the belt position information 1, 2, and 3 are set to 0 in preparation for counting the number of detections for the next 3 seconds. Next, since it is necessary to move the transfer belt 5 in the forward direction, the initial value of the incoming direction correction information is set as the eccentric cam stop position information in step S7.

Now that the initial value setting has been completed, the next step is to detect the actual position of the transfer belt 5 and to correct the stopping position of the eccentric cam 14.

In step S8, the cam motor 15 is driven to the position indicated by the eccentric cam stop position information and stopped, and in step S9, the belt motor 12 is driven to move the transfer belt 5.

Next, in step S10, a timer is started to capture the signal of the belt position detection means 16 every 10 times, and a second
In step Sll of Figure (b), the presence or absence of the transfer belt 5 is set to 1.
It is detected every 0m5, and if YES, the belt position information 1 is counted up by 1 in step S12.

This count-up is repeated until 1 in step S13.
Once the timing signal after seconds is obtained, the next step S1
4, S15 and S18 and S19 of FIG. 2(C), it is checked whether the transfer belt 5 has entered or left the belt position detection means 16, or whether it has changed in the middle.

As long as the transfer belt 5 system is operating normally according to the settings of the initial values of each of the correction information, the situation where the transfer belt 5 enters and leaves or leaves the transfer belt 5 should not occur. Therefore, at this time, the process immediately shifts to the printer operation check flow shown after D in FIG. 2(d). Further, if the change occurs during the above-mentioned process, it means that the belt meandering correction is operating normally, and the process moves on to the next fine correction process.

The above-mentioned abnormal situation of continuous entry or non-operation occurs in step S14.815 and S18 and S19 in FIG. 2(c).
Detected by

That is, if the roller belt 5 enters the belt position detecting means 16, the belt position information 2 in step S14 is
and 3 are both set to 100, and belt position information 1 increases from O to 100, so step S14
The output of step S15 becomes YES, and the output of the next step S15 also becomes YES.

Similarly, if the roller belt 5 is not detached from the belt position detection means 16, the outputs of steps S18 and S19 are both YES.

Also, in this first cycle, steps S15 and S1
Since the output of 9 never becomes No, step S16
, S17 and steps S20 and S21 are not passed.

These steps will be passed when the value of the belt position information O is changed from the next cycle onwards.

Now, if the transfer belt 5 comes off or enters the belt position detection means 16 on the way, step S1
The result of 8 is No. In this case, the process goes to step S22, and if the belt position information O is O, then the eccentric cam stop position information at that time, that is, the initial value of the incoming direction correction information is stored in the direction correction information area, and in the next step S26, the above-mentioned direction A is stored. The average of the correction information and the initial value of the B direction correction information is calculated. For example, if the initial value of the incoming direction correction information is +100 and the initial value of the B direction correction information is -100, the output of step S26 will be 0. In this way, the correction information value in the A or B direction is corrected, and the process returns to step S10 in FIG. 2(a) through the flow shown in FIG. 2(d).

If the result of step S22 is NO, step S24
If the belt position information 0 is 300, the eccentric cam stop position information at that time is stored in the B direction correction information area, and similarly, in step 826, the average of the above A direction correction information and the initial value of the B direction correction information is calculated. calculate.

Steps S27 and 828 in FIG. 2(d) are steps for updating each belt position information for the next cycle.

That is, in step S27, the latest belt position information for the past 3 seconds is set as belt position information O, and in the next step S27, belt position information 1 and 2 are set as belt position information 2 and 3, respectively, in order to move them down by 1 second. and set belt position information 1 to O.

Steps 329 to S35 are a flow for checking the operation of the device. That is, in step S29, the eccentric cam 1
4, the presence or absence of paper 1 is checked in step S30, the timeout of the correction timer is checked in step S32, an abnormal position of the transfer belt 5 is detected in step S33, and step S34 is performed depending on the abnormality. An error is displayed in step S35, and the apparatus is stopped in step S35.

Now, the eccentric cam stop position information value is corrected in step S26, and when the process returns to step S10 and enters the next cycle, a negative result will occur in steps S15 and S19.

If the result of step S15 is No, it means that the transfer belt 5 has not been detected by the belt position detecting means for the past three consecutive seconds and has entered the belt position detecting means for the next one second. Therefore, the process proceeds to step S16. The eccentric cam stop position information at that time is stored in the backward correction information area, and in step S17, the initial value of the B direction correction information is reset as the eccentric cam stop position information. Similarly, if the result of step S19 is NO, the eccentric cam stop position information at that time is stored in the B direction correction information area in step S20, and the initial value of the incoming direction correction information is changed to the eccentric cam stop position information in step S21. Set it again as .

As a result of the operations shown in FIGS. 2(a) to (d) explained above, the eccentric cam stop position information is updated every time it passes through step S26, and as a result, the values of the A direction correction information and the B direction correction information become close to each other. As a result, the meandering correction speed of the transfer belt 5 gradually becomes slower, so that the transfer belt 5 can be run while finely and slowly being corrected at the correct position.

Further, the time of 3 seconds for the belt position information should be set to be longer than at least one rotation time of the transfer belt 5, considering that the belt edge repeats a substantially regular change every rotation period of the transfer belt 5. is desirable.

If the time for one rotation of the transfer belt 5 is considerably long, the number of storage means for storing the belt position information 0 to 3, etc. is increased to a plurality of sets, and each set is updated and referenced at slightly shifted timing.

Further, the processor 17 constantly recognizes the conveyance position of the paper l inside the printer, and when the paper 1 is in the contact area between the photosensitive drum 6 and the transfer belt 5, the cam motor 15 is prohibited from being driven and the transfer belt 5 is moved. Prevents the printing position from shifting due to vibration.

Furthermore, if the meandering correction of the transfer belt 5 does not work properly due to some abnormality in the device, the following two protection means are provided to prevent damage to the transfer belt 5.

The first is a time-out detection means that determines that meandering cannot be corrected and stops the apparatus when the output of the belt position detection means 16 is continuously on or off for longer than a preset time; is equipped with a belt position abnormality detection sensor, which causes the apparatus to stop when the transfer belt 5 meanders to the permissible position in both directions A and 8.

〔Effect of the invention〕

According to the present invention, by only detecting the position of one end of the transfer belt, the transfer belt can be corrected from the position when the power is turned on to an appropriate position, and the meandering width of the transfer belt can be reduced. Quality can be improved.

Furthermore, abnormalities in meandering correction of the transfer belt can be easily detected.

Further, the belt meandering correction control device of the present invention can be applied not only to the transfer belt mechanism of an electrophotographic printing device but also to various belt conveyance devices in general to obtain similar effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a transfer belt driving and meandering correction device according to the present invention, FIGS. 2(a) to (d) are flowcharts showing control procedures of the present invention, and FIG. 3 is a block diagram of a laser beam printer. FIG. 4 is a diagram of the transfer belt drive and meandering correction mechanism. 1 is paper, 2 is a paper feed hopper, 3 is a paper feed roller, 4 is a transport roller, 5 is a transfer belt, 6 is a photosensitive drum, 7.8 is each charging corotron, 9 is a fixing device, 10 is a stacker, 11 is a A driving roller, 12 a belt motor, 13 a driven roller,
14 is an eccentric cam, 15 is a cam motor, 16 is a belt detection means, 17 is a processor, 18 is an I10 port, 19 is a driver, and 20 is a memory.

Claims (1)

[Scope of Claims] 1. A transfer belt supported by a driven roller and a drive roller and moved by the drive roller, a cut sheet is conveyed by the transfer belt, and a belt position detecting means detects a positional deviation of an end of the transfer belt. of the electrophotographic printing apparatus, in which a belt meandering correcting mechanism changes the parallelism between the driven roller and the driving roller to control the moving direction of the transfer belt, and a photosensitive drum forms a toner image on the cut paper. At the belt control position, the belt position detecting means is provided with a timer device that drives the belt position detecting means at a predetermined cycle, and a processor that calculates correction information of the belt meandering correction mechanism from belt position information outputted by the belt position detecting means. Characteristic belt meandering correction control device. 2. A transfer belt supported by a driven roller and a drive roller and moved by the drive roller is provided, the cut paper is conveyed by the transfer belt, the positional deviation of the end of the transfer belt is detected by a belt position detection means, and the belt meandering is detected. In the belt control device of an electrophotographic printing apparatus, the moving direction of the transfer belt is controlled by changing the parallelism between the driven roller and the driving roller by a correction mechanism, and a toner image is formed on the cut paper by a photosensitive drum. a timer device that drives the belt position detection means at a predetermined cycle; a storage device for belt position information outputted by the belt position detection means; a storage device for correction information of the belt meandering correction mechanism; A belt meandering correction control device comprising: a processor that calculates a correction value of the correction information of the belt meandering correction mechanism based on the correction information, and drives the belt meandering correction mechanism based on the correction value of the correction information. . 3. In claim 2, the belt position information storage device is provided with at least first and second storage areas for sequentially storing the belt position information within two consecutive predetermined times, and the processor is configured to The belt meandering correction control device is characterized in that the correction value of the correction information of the belt meandering correction mechanism is calculated by comparing the belt position information of each of the belt meandering correction mechanism and the belt position information of the second storage area. 4. Claims 2 and 3, further comprising storage means for storing the rightward and leftward values of the correction information, respectively;
When the power is turned on, initial values of rightward and leftward correction information are set in the correction information storage means, and when the belt position detection means detects that the transfer belt is in a rightward position, the belt meandering correction mechanism is activated. is driven by the initial value of the leftward correction information, and at the same time, rightward belt initial position information is stored in a first storage area of the belt position information, and it is detected that the transfer belt is in a leftward position. In this case, the belt meandering correction mechanism is driven by the initial value of the rightward correction information, and at the same time, the leftward belt initial position information is stored in the first storage area of the belt position information. Belt meandering correction control device. 5. In claims 2 to 4, the processor executes an abnormality search process for the electrophotographic printing device when the first and second belt position information is equal to the left-sided or right-sided belt initial position information. A belt meandering correction control device characterized by: 6. In claims 2 to 5, when the first belt position information is different from the two belt initial position information and the second belt position information is equal to the left or right belt initial position information, The belt meandering correction control device is characterized in that the belt meandering correction mechanism is driven by the initial value of the rightward or leftward correction information. 7. In claims 2 to 6, when the first and second belt position information is different from either of the two belt initial position information, the processor controls the belt meandering correction mechanism in the rightward and leftward directions. A belt meandering correction control device characterized in that it is driven by an average value of belt meandering correction information. 8. The belt meandering correction control device according to any one of claims 1 to 7, wherein the belt position detection means outputs a pulse signal synchronized with a timing signal of the timer device in response to the detection of the cut paper. .