JP2001231289A - Image forming apparatus and method for controlling drive of motor of image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve the throughput during double side printing sequence by remarkably shortening the time from a forward rotation of a switch-back conveying or the like in a small power source capacity via stoppage and a reverse rotation to an arrival at stationary reverse rotational speed. SOLUTION: When a motor 31 is driven from a forward rotation to a reverse rotation during a double side printing mode for driving a rotor from the forward rotation to the reverse rotation in the case of executing a predetermined image forming sequence, a limit value of a drive current flowing to the motor 31 is changed within the maximum current value in the cases of the forward drive and the reverse drive of the motor 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus having a motor for driving a rotating body to rotate forward or reverse in accordance with execution of a predetermined image forming sequence, and to a method of controlling motor driving of the image forming apparatus.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view for explaining the structure of an engine unit of a conventional image forming apparatus.

In FIG. 1, reference numerals 1Y, 1M, 1C, and 1Bk denote photosensitive drums, which are charged by a charging roller 2 and then modulated based on image data from separate laser scanner units 3Y, 3M, 3C, and 3Bk. A latent image is formed by the laser beam, and the formed latent image is
Y, 4M, 4C, and 4Bk are developed, and the developed toner image is transferred to the transfer material 8 at the position of the transfer roller 5. Note that the transfer material 8 is stored in the transfer material storage unit 6.

The transfer material 8 is picked up and fed by a pickup roller 7 at a predetermined timing, conveyed to a fixing unit 10 by a conveyance belt 9, and the transfer material 8 on which a transfer image is fixed by the fixing unit 10 is transferred. A paper discharge port (in the direction of the arrow shown in FIG. 8) by the paper discharge roller 11 according to the print mode.
After being conveyed to a predetermined position by the discharge roller 11, the discharge roller 11, which can be rotated forward or backward, is rotated in the reverse direction, and the flapper 12 is switched to be conveyed to the double-sided conveyance roller 13. You.

The image forming apparatus includes a plurality of motors (not shown) for driving various rollers, for example,
It has a C motor.

[0006]

In an image forming apparatus provided with a rotating body (e.g., a paper discharge roller) driven by a motor capable of rotating forward or backward, each of the image forming apparatuses is provided with the following steps. It is necessary to increase the current limiter of the motor, and as a result, there is a problem that the capacity of the power supply must be increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus having a motor for driving a rotating body to rotate forward or backward in accordance with execution of a predetermined image forming sequence. In the forming apparatus, when the motor is driven from normal rotation to reverse rotation, by changing the limit value of the drive current flowing through the motor within the maximum current value between the case where the motor is driven forward and the case where the motor is driven reversely, With a small power supply capacity, image formation that can significantly improve the throughput during double-sided printing sequences by dramatically shortening the time required to stop from normal rotation such as switchback conveyance and reverse rotation to reach a steady reverse rotation speed, and achieve a marked improvement in throughput during double-sided printing sequence An object of the present invention is to provide an apparatus and a method for controlling motor drive of an image forming apparatus.

[0008]

According to a first aspect of the present invention, there is provided an image forming apparatus having a motor for driving a rotating body to rotate forward or reverse in accordance with execution of a predetermined image forming sequence, A driving means (e.g., corresponding to the driver 37 shown in FIG. 1) for applying a driving current for driving the motor from the forward rotation to the reverse rotation, and when the driving current value applied to the motor exceeds a set limit value. A limiting unit (corresponding to, for example, the IC 36 shown in FIG. 1) for interrupting a driving current to be applied from the driving unit to the motor, and a case where the motor is driven forward and reversely. On the other hand, a control means (for example, equivalent to the IC 36 shown in FIG. 1) for changing the limit value is provided.

According to a second aspect of the present invention, the driving means is configured to perform the forward rotation and the reverse rotation of the motor in a range not exceeding the limit value variably set by the control means. The duty ratio of the PWM signal to be applied to the motor is changed.

According to a third aspect of the present invention, there is provided a current detecting means (corresponding to, for example, an IC 56 shown in FIG. 3) for detecting a drive current value applied to the motor, The drive current is interrupted by comparing the drive current value detected by the detection means with the limit value.

According to a fourth aspect of the present invention, the control means continuously changes the limit value in accordance with a continuous value detected by the current detecting means.

According to a fifth aspect of the present invention, the control means associates the limit value with a plurality of values separated by a specific threshold from continuous values detected by the current detection means. Are changed discretely.

According to a sixth aspect of the present invention, in the double-sided printing mode, the motor drives forward rotation or reverse rotation.

According to a seventh aspect of the present invention, in the double-sided printing mode, the motor is driven to rotate normally, temporarily stopped, and then driven to rotate reversely to switch between the paper discharge drive for the transfer material and the switchback drive. Things.

An eighth invention according to the present invention is a motor drive control method for an image forming apparatus having a motor for driving a rotating body to rotate forward or reverse in accordance with execution of a predetermined image forming sequence. A driving step (step (3) shown in FIG. 6) for applying a driving current for performing a reverse rotation driving from a forward rotation driving, and when the driving current value applied to the motor exceeds a set limit value, A limiting step (not shown) for interrupting a drive current to be applied to the motor from a drive unit, and changing the limit value to the limit unit in a case where the motor is driven forward and a case where the motor is driven reversely. Change step (step (6) shown in FIG. 6).

According to a ninth aspect of the present invention, in the driving step, when the motor is driven forward and reversely, the driving step is performed within a range not exceeding the limit value variably set by the control means. The duty ratio of the PWM signal to be applied to the motor is changed.

A tenth invention according to the present invention has a current detecting step (not shown) for detecting a drive current value applied to the motor, and the limiting step is detected by the current detecting step. The drive current is cut off by comparing the drive current value with the limit value.

According to an eleventh aspect of the present invention, in the changing step, the limit value is changed continuously in correspondence with a continuous value detected in the current detecting step.

In a twelfth aspect according to the present invention, in the changing step, the limit value corresponds to a plurality of values separated by a specific threshold from continuous values detected by the current detecting step. Are changed discretely.

According to a thirteenth aspect of the present invention, in the double-sided printing mode, the motor drives forward rotation or reverse rotation.

According to a fourteenth aspect of the present invention, in the double-sided printing mode, the motor is driven forward, temporarily stopped, and then driven reversely to switch between the paper discharge drive for the transfer material and the switchback drive. Things.

[0022]

[First Embodiment] FIG. 1 is a diagram for explaining an example of a drive control circuit of an image forming apparatus according to a first embodiment of the present invention. Hereinafter, in the present embodiment, a motor (DC brushless motor) for driving the paper discharge roller 11 capable of normal rotation or reverse rotation shown in FIG. 8 will be described as an example of the roller.

In FIG. 1, a DC brushless motor (hereinafter, simply referred to as a motor) 31 has a U-, V-, and W-phase three-phase star-connected coil 32 and a rotor 33. It comprises three Hall elements 34U, 34V, 34W for detecting 33 magnetic poles,
The output is, for example, a DSP (Digital Sign)
alProcessor) IC3 for driving control
6 is connected.

Further, there is provided a timing pattern (not shown) provided on the outer periphery of the rotor 33 and a rotational speed detecting means composed of an MR sensor 35.
Connected to.

A driver 37 includes high-side transistors 38U, 38V, 38W and low-side transistors 39U, 39V, 39W for driving the motor 31.
The coils are connected corresponding to U, V, and W of the coil 32, respectively.

The IC 36 specifies the position of the rotor 33 based on the roller position signals HU, HV, HW generated by the Hall element 34, and generates phase switching signals UU, UV, UW and phase switching signals LU, LV, LW.

The phase switching signals UU, UV, UW and the phase switching signals LU, LV, LW control on / off of the transistors (high side transistors 38U, 38V, 38W and low side transistors 39U, 39V, 39W) of the driver 37. Thus, the phases to be excited are sequentially switched to rotate the rotor 33.

Further, the IC 36 compares the rotation speed target value with the rotation speed information, generates a PWM signal, and outputs it to the NAND gates 40W, 40V, 40U. In addition, PW
When the M signal is composed of, for example, 8 bits,
At “0”, the duty is “0”%, and at “255”, the duty is “100”%.

Also, the PWM signal is a phase switching signal UU, U
V, UW and logical AND (NAN) in logical AND circuit 40
After taking D), it is used as a signal for driving current chopping control, and controls the rotation speed of the motor 31.

In this embodiment, the current limiter value is changed by changing the duty ratio. That is, when printing is started, a plurality of loads necessary for the printing process are started simultaneously, and there is a risk that the current flowing through the image forming apparatus exceeds the maximum current Ipeak.

Therefore, a current limit is provided for each motor, and the motors are controlled so that the sum does not exceed the maximum current Ipeak.

FIG. 2 is a timing chart for explaining the drive control of the paper discharge roller 11 shown in FIG. 1, in which the duty of PWM is set to "75"% at the start of normal rotation. However, the duty ratio is determined by the specifications of the device. If the maximum current Ipeak has a margin with respect to the power supply capacity, the PW at the start-up
In the M waveform, the duty is “100”%, and the activation period t
It is desirable to shorten 1.

When the motor, which is the load, reaches a steady rotation, the duty of the PWM waveform is reduced (in the example of FIG. 2, "25"%), and the state of the steady rotation is maintained. After the image printed on the surface of the transfer material 8 conveyed in the image forming apparatus is fixed by the fixing device 10 in this manner, when the switchback position is reached, the switching between the sheet discharge drive and the switchback is performed. Then, the motor 31 is temporarily stopped,
It is restarted so that the rotation direction is reversed.

At this time, the other loads started simultaneously with the start of printing are already operating at a steady rotation. When the current limiter is constant, the PWM waveform W1
As shown by {circle around (1)}, the reverse rotation steady rotation is reached in the same startup time t2 as the first startup. In this case, the current value is
This indicates an increase by the current limit value of the switchback motor, and there is a margin with respect to the total current at the start of printing.

On the other hand, if the current limiter is variable as in the present embodiment, as shown by the PWM waveform W2, the rotation reaches the reverse rotation steady rotation over the startup time t3. It should be noted that the arrival time to the steady rotation increases within the limit value by d in the figure as compared with the case where the current is constant at the limiter value, but can be shortened.

Thus, the time required for a series of operations of the paper discharge drive / switchback motor, ie, the time required for forward rotation, stoppage, and reverse rotation, is the time required for transporting the front-printed transfer material to the re-feeding port through the duplex unit. Because they are so related,
By reducing this time, it is possible to significantly improve the throughput in the double-sided printing mode.

[Second Embodiment] FIG. 3 is a diagram illustrating an example of a drive control circuit of an image forming apparatus according to a second embodiment of the present invention. Hereinafter, in the present embodiment, as a roller,
A motor (DC brushless motor) for driving the paper discharge roller 11 capable of rotating forward or reverse shown in FIG. 8 will be described as an example.

In FIG. 3, a DC brushless motor 51
Has a three-phase star-connected coil 52 and a rotor 53 of U, V, and W, and further includes three Hall elements 54 for detecting the magnetic poles of the rotor 33 as position detecting means of the rotor 33. For example, a DSP (Digital S
The IC 56 is connected to an IC 56 that controls the driving of an IC (signal processor) or the like.

Further, it has a magnetic pattern (not shown) provided on the outer periphery of the rotor 53 and a rotational speed detecting means composed of an MR sensor 55.
Connected to.

Reference numeral 57 denotes a driver, which drives the high-side transistors 58U and 5U to drive the DC brushless motor 51.
8V, 58W and low-side transistors 59U, 59V, 5
9W and the like, and are connected corresponding to U, V, W of the coil 52, respectively.

The IC 56 specifies the position of the rotor 53 based on the roller position signals HU, HV, HW generated by the Hall element 54, and generates phase switching signals UU, UV, UW and phase switching signals LU, LV, LW.

The phase switching signals UU, UV, UW and the phase switching signals LU, LV, LW control on / off of the transistors (high side transistors 58U, 58V, 58W and low side transistors 59U, 59V, 59W) of the driver 57. Thus, the phases to be excited are sequentially switched to rotate the rotor 53.

Further, the IC 56 compares the rotation speed target value with the rotation speed information, generates a PWM signal, and outputs the PWM signal to the NAND gates 60W, 60V, 60U. In addition, PW
When the M signal is composed of, for example, 8 bits,
At “0”, the duty is “0”%, and at “255”, the duty is “100”%.

The PWM signal is a phase switching signal UU, U
V, UW and logical product negation by logical product negation circuit 60 (NAN
After taking D), it is used as a signal for driving current chopping control, and controls the rotation speed of the motor 51.

In the present embodiment, the load current Isys of the image forming apparatus main body is monitored, and the maximum current REF that can be supplied to the motor for driving the paper discharge roller 11 with respect to the maximum current Ipeak is calculated. The current limiter 61 is operated from the result of the comparison to cut off the current.

That is, when printing is started, a plurality of necessary loads are started simultaneously, and there is a risk that the current flowing through the image forming apparatus exceeds the maximum current Ipeak. Therefore, a current limit is provided for each, and the motor is controlled as shown in FIG. 4 so that the sum does not exceed the maximum current Ipeak.

FIG. 4 is a timing chart for explaining the drive control of the paper discharge roller 11 shown in FIG. 3, and the current limit value of the motor driving the paper discharge roller 11 at the time of starting the normal rotation is set to a value b- The description is based on the case where the total current flowing through the entire apparatus becomes the maximum current Ipeak when the apparatus is started simultaneously with the setting of c. Note that bc is determined by the specifications of the device.

In the figure, the PWM waveform at start-up has a duty of “100”%. When the current flowing through the motor 51 reaches the maximum current REF, the current is cut off, and the current is re-flowed. Start up to

When the motor, which is a load, in the image forming apparatus reaches a steady rotation, the duty of the PWM waveform is reduced (25% in the figure), and the state of the steady rotation is maintained. Transfer material 8
After the image printed on the surface is fixed by the fixing device 10,
When the switchback position is reached, the motor 51 is temporarily stopped to switch between the paper ejection drive and the switchback, and is restarted so that the rotation direction is reversed. At this time,
The load started at the same time as the start of printing is in a state of already operating at a steady rotation.

When the current limiter is constant,
The reverse rotation steady rotation is reached over the startup time t1, which is the same as the first startup. At this time, the current value indicates an increase by the current limit value of the paper discharge drive / switchback motor, and has a margin with respect to the total current at the start of printing.

On the other hand, if the current limiter is variable as in the present embodiment, the current limit value is increased by increasing the maximum current REF, and the current that can be supplied to the motor driver 57 can be increased. The time to reach is time t2 (t2 <t1). The time required to reach steady rotation is increased by d in the figure as compared with the case where the current is equal to the limiter value, but can be shortened.

Thus, the time required for a series of operations of the paper discharge drive / switchback motor, ie, the time required for normal rotation, stop, and reverse rotation, is equal to the time required to convey the front-printed transfer material through the duplex unit to the paper feed port. Because they are so related,
By reducing this time, it is possible to significantly improve the throughput in the double-sided printing mode.

[Third Embodiment] In the second embodiment,
The load current Isys of the image forming apparatus main body is set to A /
Although the case of analog monitoring at the D port has been described, a configuration may be adopted in which the value output to the maximum current REF is limited to be used by binary monitoring at a certain threshold value. Hereinafter, the embodiment will be described.

FIG. 5 is a diagram illustrating an example of a drive control circuit of an image forming apparatus according to a third embodiment of the present invention. Hereinafter, in the present embodiment, a motor (DC brushless motor) for driving the paper discharge roller 11 capable of normal rotation or reverse rotation shown in FIG. 8 will be described as an example with reference to FIG.

In FIG. 5, the DC brushless motor 33
Has a coil 52 and a rotor 53 connected in a three-phase star connection of U, V, and W, and further includes three Hall elements 54 for detecting the magnetic pole of the rotor 53 as position detecting means of the rotor 53, and the output thereof is For example, a DSP (Digital S
The IC 56 is connected to an IC 56 that controls the driving of an IC (signal processor) or the like.

Further, it has a magnetic pattern (not shown) provided on the outer periphery of the rotor 53 and a rotational speed detecting means composed of an MR sensor 55.
Connected to.

Reference numeral 57 denotes a driver which drives the high-side transistors 58U and 5U to drive the DC brushless motor 51.
8V, 58W and low-side transistors 59U, 59V, 5
9W and the like, and are connected corresponding to U, V, W of the coil 52, respectively.

The IC 56 specifies the position of the rotor 53 based on the roller position signals HU, HV, HW generated by the Hall element 54, and generates phase switching signals UU, UV, UW and phase switching signals LU, LV, LW.

The phase switching signals UU, UV, UW and the phase switching signals LU, LV, LW control ON / OFF of each transistor (high side transistors 58U, 58V, 58W and low side transistors 59U, 59V, 59W) of the driver 57. Thus, the phases to be excited are sequentially switched to rotate the rotor 53.

Further, the IC 56 compares the rotation speed target value with the rotation speed information, generates a PWM signal, and outputs the PWM signal to the NAND gates 60W, 60V, and 60U.

When the PWM signal is composed of, for example, 8 bits, it is “0”, the duty is “0”%,
It is assumed that the duty becomes "100"% at "255".

Further, the PWM signal is a phase switching signal UU, U
V, UW and logical product negation by logical product negation circuit 60 (NAN
After taking D), it is used as a signal for driving current chopping control, and controls the rotation speed of the motor 51.

In this embodiment, the load current Isys of the main body of the image forming apparatus is monitored by a binary signal which changes at a certain threshold, and the maximum current REF is changed according to the change of the signal.
Is switched by a binary signal. With this configuration, a special port necessary for the IC 56 that controls the drive control is not required, and the sequence of the drive control can be simplified.

That is, when printing is started, a plurality of necessary loads are started simultaneously, and there is a risk that the current flowing through the image forming apparatus exceeds the maximum current Ipeak. Therefore, a current limit is provided for each motor, and the driving of the motors is controlled so that the sum does not exceed the maximum current Ipeak.

In FIG. 5, when the motor for driving the paper discharge roller 11 in the image forming apparatus is set to bc at the same time when the normal rotation starts, the total current flowing through the entire apparatus is maximized. The case where the current becomes Ipeak is described. Note that bc in the figure is determined by the specifications of the device.

The PWM waveform at the time of starting has a duty “10”.
0 "%, and the current flowing through the motor 51 is the maximum current RE
When the value of F is reached, the current is cut off, and the control is started again by repeating the control for flowing the current again.

When the motor, which is the load, reaches a steady rotation, the duty of the PWM waveform is reduced (in FIG.
%), And maintain a state of steady rotation.

When the transfer material 8 reaches the switchback position after the image printed on the front surface of the transfer material 8 is fixed by the fixing device 10, the motor 51 is temporarily stopped in order to switch between the paper discharge drive and the switchback. Is restarted so that the rotation direction is reversed.

At this time, the other loads started simultaneously with the start of printing are already operating at the steady rotation. When the current limit is constant, if it is the same as the first start-up, the rotation reaches the reverse normal rotation over time t1.
The current indicates an increase by the current limit value of the discharge drive / switchback motor, and has a margin compared to the total current at the start of printing.

On the other hand, if the current limiter is variable as in the present embodiment, the current that can be supplied to the motor driver 57 by switching the current limit value can be increased. t1). In addition, the arrival time to the steady rotation increases by the value d as compared with the case where the current is constant, but can be shortened.

The difference between the third embodiment and the second embodiment is that the values bc and d in FIG. 4 are fixedly set by hardware.

In particular, in the third embodiment, the case where the load current monitoring port of the image forming apparatus main body is set to, for example, 1 bit and switching between two states of "0" or "1" is described. Needless to say, it is possible to configure so that more states can be switched by increasing the number of monitoring ports.

As a result, the time required for a series of operations of the sheet discharge drive / switchback motor, ie, the time required for normal rotation, stoppage, and reverse rotation, is reduced to the time required to convey the front-surface-printed transfer material through the duplex unit to the paper feed port. Because they are so related,
By shortening this time, it is possible to significantly improve the throughput in the double-sided printing mode,
The cost of the entire apparatus can be reduced.

FIG. 6 is a flowchart showing an example of a motor drive control procedure in the image forming apparatus according to the present invention. Note that (1) to (10) indicate each step, and the procedure shown in each step is stored in the memory of the ROM in the IC 36.

First, in step (1), it is determined whether or not the double-sided printing mode is set. If NO, in step (2), the discharge rollers 11 are set to the normal printing mode.
, The PWM duty is set to “75%”, and the drive is completed, thereby ending the reverse rotation drive processing.

On the other hand, if "YES" is determined in the step (1), the duty of the PWM is set to "75"% for the discharge roller 11 for printing on the first printing surface in the step (3). When the motor, which is the load, reaches the steady rotation, the duty of the PWM waveform is reduced (in the example of FIG. 2, "25"%), and the state of the steady rotation is maintained.

Then, in step (4), it is determined whether or not the transferred transfer material is at a switchback timing.
If O, the process returns to step (3) until the transfer material reaches the switchback timing, and YES, that is, the image printed on the surface of the transfer material 8 conveyed in the image forming apparatus by the fixing device 10 is fixed. After that, when the switchback position is reached, it is determined in step (5) whether or not image formation is on the first surface.
In the case of ES, the motor 31 is temporarily stopped in step (6) to switch between the paper ejection drive and the switchback, and in step (7), the current limit value (limit value) is variably set by the d value. Then, in step (8), the PWM waveform W2
In step (9), the switchback driving time elapses after the start time t3, and when the switchback driving time elapses in step (9),
In step (10), return to step (3).

Hereinafter, the configuration of a data processing program readable by the image forming apparatus according to the present invention will be described with reference to a memory map shown in FIG.

FIG. 7 is a view for explaining a memory map of a storage medium for storing various data processing programs readable by the image forming apparatus according to the present invention.

Although not shown, information for managing a group of programs stored in the storage medium, for example, version information, a creator, etc. is also stored, and information dependent on the OS or the like on the program reading side, for example, a program is stored in the storage medium. An icon or the like for identification display may also be stored.

Further, data dependent on various programs is also managed in the directory. In addition, a program for installing various programs on a computer or a program for decompressing a program to be installed when the program to be installed is compressed may be stored.

The functions shown in FIG. 6 in this embodiment may be executed by a host computer by a program installed from the outside. In this case, the present invention is applied even when a group of information including a program is supplied to the output device from a storage medium such as a CD-ROM, a flash memory, or an FD, or from an external storage medium via a network. Things.

As described above, the storage medium storing the program code of the software for realizing the functions of the above-described embodiments is supplied to the system or the apparatus, and the computer (or CPU or MP) of the system or the apparatus is supplied.
It goes without saying that the object of the present invention is also achieved when U) reads and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.

Examples of a storage medium for supplying the program code include a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, and C
DR, magnetic tape, nonvolatile memory card, RO
M, EEPROM and the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) And the like perform part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, The CPU provided in the function expansion board or function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

[0088]

As described above, the first embodiment according to the present invention is described.
According to the fourteenth aspect, in the image forming apparatus having the motor that drives the rotating body in the forward rotation or the reverse rotation with the execution of the predetermined image forming sequence, when the motor is driven from the forward rotation to the reverse rotation, the motor is driven. Since the limit value of the drive current flowing through the motor is changed within the maximum current value between the case of the forward rotation drive and the case of the reverse rotation drive, the rotation is stopped from the forward rotation such as the switchback conveyance and the reverse rotation with a small power supply capacity. This has the effect of significantly shortening the time required to reach the steady number of reverse rotations and significantly improving the throughput during the double-sided printing sequence.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a drive control circuit of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining drive control of a discharge roller shown in FIG. 1;

FIG. 3 is a diagram illustrating an example of a drive control circuit of an image forming apparatus according to a second embodiment of the present invention.

FIG. 4 is a timing chart for explaining drive control of a discharge roller shown in FIG. 3;

FIG. 5 is a diagram illustrating an example of a drive control circuit of an image forming apparatus according to a third embodiment of the present invention.

FIG. 6 is a flowchart illustrating an example of a motor drive control procedure in the image forming apparatus according to the present invention.

FIG. 7 is a diagram illustrating a memory map of a storage medium that stores various data processing programs that can be read by the image forming apparatus according to the present invention.

FIG. 8 is a cross-sectional view illustrating a configuration of an engine unit of a conventional image forming apparatus.

[Explanation of symbols]

 31 motor 32 coil 33 rotor 34 hall element 35 MR sensor 36 IC 37 driver

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02P 6/06 H02P 6/02 341J F term (Reference) 2H027 DA01 EC10 EE04 FA13 2H072 AA32 AB07 JA08 3F049 EA17 LA04 LB03 5H560 AA04 BB04 BB07 DA02 DA04 DA19 DC12 EB01 GG04 HC04 JJ02 SS01 TT12 TT13 UA02 XA12 9A001 HH34 KZ42

Claims (14)

[Claims] 1. An image forming apparatus having a motor for driving a rotating body to rotate forward or backward in accordance with execution of a predetermined image forming sequence, wherein a driving current for rotating the motor from forward rotation to reverse rotation is applied. A driving unit that cuts off a driving current to be applied to the motor from the driving unit when a driving current value applied to the motor exceeds a set limit value; An image forming apparatus comprising: a control unit that changes the limit value with respect to the limiting unit when driving and when rotating in reverse. 2. The drive unit according to claim 1, wherein the drive unit controls the PWM to be applied to the motor within a range not exceeding the limit value variably set by the control unit when the motor is driven forward and reversely. 2. The image forming apparatus according to claim 1, wherein the duty ratio of the signal is changed. 3. A current detecting means for detecting a drive current value applied to the motor, wherein the limiting means compares the drive current value detected by the current detecting means with the limit value. The image forming apparatus according to claim 1, wherein the driving current is interrupted by turning off the driving current. 4. The image forming apparatus according to claim 1, wherein the control unit changes the limit value continuously according to a continuous value detected by the current detection unit. 5. The method according to claim 5, wherein the control unit discretely changes the limit value so that a continuous value detected by the current detection unit corresponds to a plurality of values separated by a specific threshold value. The image forming apparatus according to claim 1, wherein: 6. The motor according to claim 1, wherein the motor is driven to rotate forward or reverse in a duplex printing mode.
The image forming apparatus as described in the above. 7. The motor according to claim 1, wherein the motor is driven in a normal rotation mode, temporarily stopped in a double-sided printing mode, and is further driven in a reverse rotation mode to switch between a paper discharge drive and a switchback drive for the transfer material. The image forming apparatus as described in the above. 8. A motor drive control method for an image forming apparatus having a motor for driving a rotating body to rotate forward or reverse in accordance with execution of a predetermined image forming sequence, the method comprising: rotating the motor from forward rotation to reverse rotation. A drive step of applying a drive current of, and a limit step of cutting off a drive current to be applied to the motor from the drive means when a drive current value applied to the motor exceeds a set limit value; A motor driving control method for an image forming apparatus, comprising: a changing step of changing the limit value with respect to the limiting unit when the motor is driven forward and reversely. 9. The method according to claim 1, wherein the driving step includes a step of controlling the PWM to be applied to the motor within a range not exceeding the limit value variably set by the control means when the motor is driven forward and reversely. 9. The method according to claim 8, wherein the duty ratio of the signal is changed. 10. A current detecting step for detecting a driving current value applied to the motor, wherein the limiting step compares the driving current value detected by the current detecting step with the limit value. 9. The method according to claim 8, wherein the drive current is interrupted by the drive. 11. The motor according to claim 8, wherein in the changing step, the limit value is changed continuously corresponding to a continuous value detected in the current detecting step. Drive control method. 12. The method according to claim 11, wherein the changing step discretely changes the limit value so that continuous values detected by the current detecting step correspond to a plurality of values separated by a specific threshold value. 9. The method according to claim 8, wherein the motor drive control is performed on the image forming apparatus. 13. The motor according to claim 1, wherein the motor is in a double-sided printing mode.
9. The method according to claim 8, wherein the motor is driven forward or reverse. 14. The motor according to claim 11, wherein the motor is in a double-sided printing mode.
9. The motor drive control method for an image forming apparatus according to claim 8, wherein the motor is driven forward, temporarily stopped, and further driven reversely to switch between sheet discharge drive and switchback drive for the transfer material.