JP2007307756A - Driving controlling apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving controlling apparatus capable of suppressing down time of a driving mechanism at a minimum and realizing a driving operation having no influence on a printed image. <P>SOLUTION: The driving controlling apparatus is equipped with an abnormal operation detecting means 14 for detecting an abnormal operation of a driving means 12 from the amount of driving given to the driving means 12 from a position movement controlling means 11 when the driving means 12 is driven and the amount of movement detected by a means 13 for detecting the amount of movement, and a stopping judging means 15 for judging whether driving controlling of the driving means 12 by a position movement controlling means is stopped. When it is judged that the operation of the driving means 12 is abnormal by the detecting result of the abnormal operation detecting means 14, the stopping judging means 15 does not perform stopping judgement even when the position of a body 20 to be driven reaches a target position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drive control device that controls driving of a motor, and an image forming apparatus such as an ink jet printer including the drive control device.

Currently, motors are used as drive sources for various devices. In particular, in an image recording apparatus such as an ink jet recording apparatus, a motor is used for a main scanning mechanism for reciprocating a recording head and a sub-scanning mechanism for transporting a recording medium. In addition, position control and speed control of the recording medium are performed. In addition, higher speed and higher accuracy of the apparatus are desired, and more advanced position control is required in addition to mechanical accuracy.
However, there is a possibility that malfunction due to the influence of noise, which cannot normally occur, may occur due to defects in the components of the scanning mechanism or poor contact of the connector in the assembly process. In order to solve such problems, several proposals have conventionally been made as an abnormality detection method.

For example, Patent Document 1 compares the current flowing at a low speed with the current flowing at a stop, and interrupts the current as abnormal when the current flowing at a stop continues for a certain period of time rather than the current flowing at a low speed. A method for stopping the occurrence of abnormal current is disclosed. Patent Document 2 compares the drive direction according to a command to rotate the motor and the drive direction obtained from the drive signal on the motor drive circuit, and stops the motor if the comparison results do not match. A method is disclosed. Patent Document 3 discloses a method of stopping a motor when an abnormality is detected from a current detector flowing through the motor and an encoder signal for detecting the rotation amount of the motor.
Japanese Patent Laid-Open No. 10-4471 JP 2004-129382 A JP 2005-198467 A

In order to realize high-accuracy position feed control, it is an important issue how to finely adjust the position near the stop position at high speed and stably.
However, when the motor does not rotate according to the command value in response to the rotation start command value instructed by the controller due to noise jumping into the motor drive driver circuit, product assembly failure, parts failure, etc. There is.

  As an example, chattering occurs in the drive waveform due to noise superimposed on the Hall element signal of the motor drive circuit, etc., and the motor drive is normal when the motor rotation drive stops or rotates at a low speed just before the motor rotation command value. There is a state in which the rotation speed or rotation speed does not follow the command value. If rotation continues with noise superimposed on the Hall element signal in this way, there is no problem with noise when there is a certain increase in the number of rotations or rotation speed, but there is no problem with the drive at low or low rotation speeds. Even if the command value is given, a situation occurs in which the motor does not rotate. When the rotation control of the motor is performed, the drive command value may rise abnormally in a low speed region, and may suddenly accelerate from a certain drive command value.

  In an inkjet printing apparatus that performs image formation by alternately repeating paper transport and ink ejection head movement, when the paper transport is moved to a certain target position by position control, position information is used to reach the target position. Therefore, the stop determination is performed when the motor is accidentally stopped near the target position in an abnormal state where the motor does not rotate with respect to the drive command value as described above. By this stop determination, the paper has finished moving to the target position, and the printing operation by the ink head is started. Thereafter, when the rapid rotation of the motor as described above occurs, the printing is started diagonally because the printing is started after the stop determination.

As a countermeasure against such a state, it is considered that if the driving torque to the motor is set to “0” after the stop determination, the subsequent rapid movement operation does not occur. However, if the motor drive torque is set to “0” after the stop determination due to external vibrations or torsion of the mechanism transmission system, the motor cannot be controlled to be held in that position, and position deviation may occur due to vibrations or the like. There is.
Therefore, it is necessary to continue the control operation in order to stop and hold the driven body at the target stop position even after stopping at the target stop position, and it is necessary to continuously apply a certain torque to the motor and maintain the control state.

Since the occurrence frequency of such a phenomenon is very low, if the system is stopped when an abnormal operation occurs, JAM recovery or repair is required. Therefore, it is required to continue printing within a range that does not affect the printed image and the system. .
Accordingly, in view of the above, the present invention minimizes the downtime of the drive mechanism and reduces the amount of time required for printing on the print image by adopting a configuration in which the movement position control does not malfunction due to noise or the like in the motor drive signal. Provided are a drive control device and an image forming apparatus capable of realizing a drive operation that does not affect the operation.

In order to achieve the above object, a drive control device of the present invention is detected by a drive unit that drives a driven body, a movement amount detection unit that detects a movement amount of the driven body, and the movement amount detection unit. And a position control means for controlling the position of the driven body by controlling the drive amount of the drive means based on the amount of movement, and a drive control device comprising the drive means by the drive control means when the drive means is driven. An abnormal operation detecting means for detecting an abnormal operation of the driving means from the driving amount given to the moving amount detecting means, and whether the driving control of the driving means by the position control means is stopped. Stop determining means for determining whether or not the stop determining means determines the position of the driven body when the operation of the driving means is determined to be abnormal based on the detection result of the abnormal operation detecting means. Characterized in that but do not perform the stop determination even when the target position has been reached.
Further, the drive control apparatus of the present invention is characterized by comprising a set value changing means for changing a set value when the abnormal operation detecting means detects an abnormal operation.

The drive control device of the present invention is characterized in that the set value change in the set value changing means is performed based on the drive amount and speed information during normal operation.
Moreover, the drive control apparatus of the present invention is characterized in that the stop determination unit changes a stop determination condition according to a detection result of the abnormal operation detection unit.
The drive control apparatus according to the present invention further includes an abnormal operation counting unit that stores the number of times that the abnormal operation is detected by the abnormal operation detecting unit, and the stop determination unit detects the abnormal operation stored in the abnormal operation counting unit. The stop determination is performed based on the number of times.
The image forming apparatus of the present invention includes the drive control apparatus of the present invention.

According to the present invention, when the stop determination unit determines that the operation of the drive unit is abnormal based on the detection result of the abnormal operation detection unit, the stop determination is not performed even when the position of the driven body reaches the target position. With this configuration, printing can be executed without adversely affecting printing on the image.
Also, according to the present invention, the setting value changing means for changing the setting value when the abnormal operation is detected by the abnormal operation detecting means is provided, and the setting value at the time of abnormality detection can be changed by the setting value changing means. Therefore, it is possible to cope with fluctuations due to changes over time.

Further, according to the present invention, the setting value can be changed automatically by changing the setting value in the setting value changing means based on the driving amount and speed information during normal operation, and more stable driving. The operation can be realized.
Further, according to the present invention, the stop determination means changes the stop determination condition according to the detection result of the abnormal operation detection means, thereby enabling the moving operation without affecting printing.
According to the present invention, the abnormal operation counting means for storing the number of abnormal operations detected by the abnormal operation detecting means is provided, and the stop determining means determines the stop based on the number of abnormal operations detected stored in the abnormal operation counting means. System operation with less downtime can be realized.

FIG. 1 is a diagram showing a schematic configuration of a paper transport mechanism of a printing apparatus provided with a drive control device according to an embodiment of the present invention.
In FIG. 1, a driven pulley 3 attached to a paper transport shaft (not shown) is driven to rotate via a timing belt 2 by rotating a motor driven pulley 1 that is attached to a drive motor shaft (not shown) and driven to rotate. The cord wheel 4 installed on the driven pulley 3 also rotates at the same time. Therefore, by detecting the encoder slit on the code wheel 4 by the sensor 5, the rotation amount of the paper conveyance drive shaft, that is, the movement amount of the paper conveyance can be obtained.

  Therefore, in the drive control apparatus of the present embodiment, the paper on the paper transport shaft is moved to the target position by the control means based on the position information obtained by the encoder including the code wheel 4 and the sensor 5. The control amount is calculated, a control command value is given to a motor driver or the like (not shown), and the motor is driven to rotate, thereby realizing paper conveyance to the target position. In order to achieve paper conveyance to the target position with the paper conveyance mechanism as described above, move to the target position at high speed, finely adjust the position near the target position, and realize movement to the target position. The method to do is common.

FIG. 2 is a diagram showing the configuration of functional blocks that perform position movement control in the drive control apparatus of the present embodiment.
In FIG. 2, since the position movement control means 11 moves the driven body 20 to the target position, the command value given to the driving means 12 is based on the movement amount obtained from the movement amount detection means 13 attached to the driven body 20. Is obtained by calculation. At this time, the abnormal operation detection unit 14 determines whether or not the abnormal operation state is present based on the drive command value given from the position movement control unit 11 to the drive unit 12 and the movement amount in the movement amount detection unit 13. The stop determination unit 15 performs stop determination based on the detection result of the abnormal operation detection unit 14 and the movement amount from the movement amount detection unit 13, and realizes the movement of the driven body 20 to the target position.
By the way, in the drive control apparatus as described above, it is considered that noise is likely to be generated on the motor drive circuit due to a harness failure or a grounding failure that occurs in the assembly process.

3, 4, and 5 are diagrams illustrating an operation example of a result when the motor is rotationally driven in a state where noise is likely to be generated and the position movement control to the target position is performed.
3 and 4, the horizontal axis is the time (seconds) from the start of movement, the vertical left axis is the remaining movement amount to the target position near the stop position (the movement amount is indicated by the number of pulses of the encoder), and the vertical right axis Is a drive command value (drive command value is a set value in the case of PWM drive) given to the motor 12 as a drive means, and in normal operation, as shown in FIG. It moves to the position along with the passage of time, and moves to the target position (so that the target position deviation becomes “0”).
However, as shown in FIG. 4, the movement toward the target position is started, and since the drive command value of the motor 12 approaches the target position from the point where 0.02 seconds have passed, it increases in the minus direction. There is little change in the amount. In addition, as shown in FIG. 4, the place where the rotation amount of the motor 12 decreases with respect to the motor drive command value may be near the target position.

In the method of obtaining the movement amount by the number of pulses output from the encoder 13, which is the movement amount detection means, when the position movement stop determination is performed, the deviation from the target position must be detected by detecting the edge of the pulse. Since it cannot be determined (the amount of movement cannot be detected in a section where no pulse edge occurs), and in order to quickly detect the movement end time, the determination is generally made by stopping for a certain time within ± 1 pulse of the target position. It is. In the case of FIG. 5, the stop determination is made because the drive command value is stopped for a certain period of time within ± 1 pulse of the target position in the vicinity of 0.1 seconds where the drive command value fluctuates greatly.
However, when the rotation of the motor 12 stops with one pulse deviation from the target position as shown in FIG. 5, the controller 11 serving as the position movement control means tries to set the stop position to the target deviation “0”. In order to change the value, the absolute value of the motor drive command value increases while the motor 12 does not rotate. When the motor 12 starts to rotate at a certain point, the drive command value at that time is a large value. In addition, the rotation starts abruptly.

This operation occurs after it is determined that the paper transport mechanism has stopped at the target position. Therefore, during the printing operation, the paper transport mechanism moves in a state where printing by scanning of the head is started. Will be output as a bend. That is, when it is determined that the head has stopped at the target position based on the conventional position information and the printing operation is performed, the printed image may be bent.
The situation as described above occurs particularly when chattering occurs at the edge portion of the Hall element signal as shown in FIG. 6 due to noise superposition on the Hall element signal when the three-phase brushless motor is driven by PWM.
Although it is possible to take measures by analog filters such as adding capacitors and increasing the capacity, the probability of occurrence cannot be made “0” due to variations during assembly of the mass production process, and the frequency of occurrence is very rare. Therefore, it cannot be detected at the time of product inspection, and there is a possibility that it may cause a trouble after entering the market.

  Therefore, in the present embodiment, the drive unit 12 that drives the driven body 20, the movement amount detection unit 13 that detects the movement amount of the driven body 20, and the movement amount detected by the movement amount detection unit 13. In the drive control device provided with the position movement control means 11 for controlling the drive amount of the drive means 12 to control the position of the driven body 20, the position movement control means 11 gives the drive means 12 when the drive means 12 is driven. Whether or not to stop the drive control of the drive means 12 by the abnormal movement detection means 14 for detecting the abnormal operation of the drive means 12 from the drive amount and the movement amount detected by the movement amount detection means 13 and the position movement control means. Stop determination means 15 for determining, if the stop determination means 15 determines that the operation of the drive means 12 is abnormal based on the detection result of the abnormal operation detection means 14, the position of the driven body 20 is determined. There is characterized in that so as not to perform the stop determination even when the target position has been reached.

FIG. 7 is a flowchart showing the stop determination process in the stop determination means 15 described above.
The stop determination process shown in FIG. 7 starts when the movement amount detection value count is obtained from the movement amount detection means 13 shown in FIG.
In this case, first, “0” is set to Loop_c in step S1.
Next, in step S2, the movement amount detection value count is read into pos, and in the subsequent step S3, when the target movement amount is set as the target, the value obtained by adding 1 to pos and target (target + 1) is compared. If the movement amount detection value count read in pos is larger (“No” in S3), the process returns to step S1. On the other hand, if the movement amount detection value count read in pos is equal to or smaller than target + 1 (“Yes” in S3), the process proceeds to step S4.

In step S4, pos and a value obtained by subtracting 1 from target (target-1) are compared. If the movement amount detection value count read in pos is smaller (“No” in S4), the process proceeds to step S1. Return. On the other hand, if the movement amount detection value count read in pos is equal to or larger than target-1 (“Yes” in S4), the process proceeds to step S5.
In step S5, when the command value given from the position movement control means 11 to the drive means 12 is drive_val, the value of drive_val is read into cnt_val.
Next, in step S6, the value of cnt_val is compared with the upper limit value up_lim of the drive command value at the time of stop determination. If the value of cnt_val is larger (“Yes” in S6), the process returns to step S1 and cnt_val. Is equal to the upper limit value up_lim or the value of cnt_val is smaller than the upper limit value up_lim (“No” in S6), the process proceeds to step S7.

In step S7, the value of cnt_val is compared with the lower limit value low_lim of the drive command value at the time of stop determination. If the value of cnt_val is smaller (“Yes” in S7), the process returns to step S1, and cnt_val If the value and the upper limit value low_lim are equal or larger (“No” in S7), the process proceeds to step S8.
In step S8, 1 is added to the value of loop_c, and then in step S9, the value of loop_c is compared with the value of the number of repeated detections set_num at the time of stop determination, and the value of loop_c is equal to the value of set_num. Alternatively, if it is smaller, the process returns to step S2, and if the value of loop_c is larger, it is determined that the process is stopped (S10).

Next, as a second embodiment of the present invention, a changing method in the case where the abnormal value determination of the drive command value at the stop determination in FIG. 7 is performed will be described.
FIG. 8 is a diagram showing the configuration of functional blocks that perform position movement control in the drive control apparatus of the second embodiment. It should be noted that the same blocks as the functional blocks shown in FIG.
This case is characterized in that the setting value changing means 16 is provided in addition to the configuration shown in FIG. In the setting value changing means 16, by changing the values of the upper limit value up_lim and the lower limit value low_lim in the determination stop process shown in FIG. 7, the determination of the abnormal value becomes variable according to the characteristic change such as the load of the mechanism. Position movement control that is not affected by fluctuations becomes possible.

The values of the upper limit value up_lim and the lower limit value low_lim shown in FIG. 7 are measured at least several times (10 times) when the value of the drive command value at the time of normal operation stop determination is measured in advance and the measured value is set to stop_val. From the average value stop_val_ave of the absolute values of the above values (preferably), the following formulas (1) and (2) are used.
Upper limit up_lim = stop_val_ave × 1.5 (1)
Lower limit value low_lim = up_lim × (−1) (2)
Further, set_num is a value of how many sampling target values ± 1 pulse are used to complete the movement of the position in the sampling period in which the position movement control means 11 gives the drive command value to the driving means 12. If it is increased, the stop determination accuracy is improved, but the determination time is required. This value is determined by the time required for the movement of the driven body 20. By executing the stop determination process as described above, the print process can be performed without causing an erroneous stop determination when the rotational drive state of the motor 12 is abnormal.

FIG. 9 is a diagram illustrating a configuration of functional blocks that perform position movement control in the drive control apparatus of the third embodiment. The same blocks as the functional blocks shown in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.
This case is characterized in that an abnormal operation counting means 17 is provided in addition to the configuration shown in FIG. The abnormal operation counting means 17 has an abnormal operation detection circuit that counts the number of abnormal operation occurrences, and the number of abnormal occurrences counted by the abnormal operation counting means 17 is a certain value or more and the number of occurrences per time is a certain value or more. If the system condition is not satisfied, the system itself is stopped. If the determination condition is not satisfied, the printing operation is continued or a warning is given to the outside so that the system operation itself is not stopped.

FIG. 10 is a flowchart showing determination processing for continuation and stop of the system operation when the above-described abnormality occurs.
In this case, first, in step S11, when the current time is time, the current time time is stored in S_time. Next, in step S12, it is checked whether or not an abnormality has occurred. If it is determined that an abnormality has occurred, the process proceeds to step S13.
In step S13, 1 is added to the value of Err_count. In the subsequent step S14, the value of Err_count is compared with the number of error occurrences Err_lim for determining whether the system is stopped. If the value of Err_count is smaller than the value of Err_lim (in S14). "No") returns to the process of step S12. On the other hand, if the value of Err_count is greater than the value of Err_lim, the process proceeds to step S15, and the current time time is stored as E_time.

  Next, in step S16, the abnormal operation occurrence average time Err_time is obtained by the following equation Err_time = (E_timeTime) / Err_time, and in subsequent step S17, Err_time and the abnormal operation occurrence average time value ER_time for determining the system stop are compared. If Err_time is greater than ER_time (“Yes” in S17), the process returns to step S12. On the other hand, if Err_time is smaller than ER_time (“No” in S17), the system is stopped because the average occurrence time is short and the frequency of occurrence of abnormality is high (S18). By performing such an operation, a drive mechanism with less downtime can be realized. In the process of FIG. 10, the Err_lim of the abnormal operation occurrence frequency and the half-low value ER_time of the abnormal occurrence average time used as the comparison values are set as threshold values based on the result of operating the system in advance.

It is a figure showing a schematic structure of a paper conveyance mechanism of a printing apparatus provided with a drive control device concerning an embodiment of the present invention. It is the figure which showed the structure of the functional block which performs position movement control. It is the figure which showed an example of the operation result at the time of rotating a motor in the state which is easy to generate | occur | produce a noise, and performing position movement control to a target position. It is the figure which showed an example of the operation result at the time of rotating a motor in the state which is easy to generate | occur | produce a noise, and performing position movement control to a target position. It is the figure which showed an example of the operation result at the time of rotating a motor in the state which is easy to generate | occur | produce a noise, and performing position movement control to a target position. It is the figure which showed the waveform of the Hall element signal at the time of PWM drive of a three-phase brushless motor. It is the flowchart which showed the procedure of the stop determination process. It is the figure which showed the structure of the functional block which performs position movement control in the drive control apparatus of 2nd Embodiment. It is the figure which showed the structure of the functional block which performs position movement control in the drive control apparatus of 3rd Embodiment. It is the flowchart which showed the system operation continuation and stop determination processing at the time of abnormality occurrence.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Motor drive pulley, 2 ... Timing belt, 3 ... Driven pulley, 4 ... Code wheel, 5 ... Sensor, 11 ... Position movement control means, 12 ... Drive means, 13 ... Movement amount detection means, 14 ... Abnormal operation detection Means 15: Stop determining means 16 ... Setting value changing means 17 ... Abnormal operation counting means 20 ... Driven object

Claims (6)

A driving means for driving the driven body; a movement amount detecting means for detecting a movement amount of the driven body; and a driving amount of the driving means is controlled based on a movement amount detected by the movement amount detecting means. In a position control means for controlling the position of the driven body, and a drive control apparatus comprising
An abnormal operation detecting unit for detecting an abnormal operation of the driving unit from a driving amount given to the driving unit by the driving control unit during driving of the driving unit and a moving amount detected by the moving amount detecting unit; Stop determination means for determining whether or not to stop the drive control of the drive means by the position control means,
If the stop determination means determines that the operation of the drive means is abnormal based on the detection result of the abnormal operation detection means, the stop determination means does not make a stop determination even when the position of the driven body reaches a target position. A drive control device characterized by the above.   2. The drive control device according to claim 1, further comprising setting value changing means for changing a setting value when the abnormal action is detected by the abnormal action detecting means.   3. The drive control apparatus according to claim 2, wherein the set value change in the set value changing means is performed based on drive amount and speed information during normal operation.   The drive control device according to claim 1, wherein the stop determination unit changes a stop determination condition according to a detection result of the abnormal operation detection unit.   An abnormal operation counting unit that stores the number of times of abnormal operation detection by the abnormal operation detection unit is provided, and the stop determination unit performs stop determination based on the number of abnormal operation detections stored in the abnormal operation counting unit. The drive control apparatus according to claim 4.   An image forming apparatus comprising the drive control device according to claim 1.

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