JP2008206371A - Stepping motor excitation switching control unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly switch excitation modes, by eliminating the possibility of the occurrence of vibration and noise at switching of excitation modes. <P>SOLUTION: The control device comprises a CPU11 which controls switching of excitation modes of a stepping motor, a logic circuit 14 for outputting a drive signal corresponding to the excitation mode indicated from the CPU11, and a motor driver 15 for exciting coils of respective phases of a stepping motor 16 based on the drive signal outputted from the logic circuit 14. The logic circuit 14, at switching to the excitation mode indicated from the CPU11, outputs the drive signal for the indicated excitation mode to the motor river 15 at predetermined timing according to the combination of excitation modes before/after switching of excitation mode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to output timing control of a drive signal to a stepping motor when switching an excitation mode of the stepping motor.

In recent years, in an image forming apparatus, a stepping motor is widely used as a drive mechanism for each unit such as a transport mechanism for transporting a recording sheet from a paper feed cassette toward an image forming unit or a discharge tray, and an image forming unit. This stepping motor has excitation modes such as 2-phase excitation, 1-2 phase excitation, and W1-2 phase excitation, and the excitation mode is switched according to the required torque or the like. For example, Patent Document 1 below proposes a technique for suppressing phase jumps or the like by switching the excitation mode in a certain step. Patent Document 2 discloses a technique that enables low-noise driving by switching one step immediately after driving from 1-2-phase excitation driving to 2-phase excitation driving. Further, Patent Document 3 uses two-phase excitation at the time of acceleration / deceleration of the stepping motor, and uses 1-2 phase excitation, W1-2 phase excitation at the constant speed, thereby obtaining a necessary torque at the time of acceleration / deceleration. A control method that can reduce the current at a constant speed is disclosed.
Japanese Patent No. 3219601 JP 2000-25978 A JP 2000-108443 A

  However, any of the techniques disclosed in the above patent documents may generate vibration and noise when switching the excitation mode, and further improvement is desired for smooth switching of the excitation mode.

  FIG. 7 shows a control signal pattern and a motor current waveform given to the motor driver during two-phase excitation and 1-2 phase excitation. CLK A and CLK B are motor clock signals applied to the A phase and the B phase, respectively, I0 and I1 are A phase current controllers, and I2 and I3 are B phase current controllers. FIG. 6 shows a conventional control signal pattern and motor current waveform when switching from 2-phase excitation to 1-2-phase excitation. As shown in FIG. 7, in each excitation mode, the motor current waveform is ideally close to a sine wave. However, as shown in FIG. 6, when the excitation mode is switched, the peak interval of the motor current waveform is, for example, 4.5 steps if the original 1-2 phase excitation peak interval is 4 steps. A situation occurs in which the interval increases. The deviation of 0.5 step prevents smooth switching of the excitation mode and may cause problems such as vibration and noise. Further, the deviation of 0.5 step cannot be corrected by changing the excitation mode switching timing from the 2-phase excitation to the 1-2 phase excitation.

  The present invention has been made to solve the above problem, and an object of the present invention is to eliminate the possibility of generating vibration and noise when switching the excitation mode and to smoothly switch the excitation mode.

The invention according to claim 1 of the present invention includes a control unit that switches and controls the excitation mode of the stepping motor;
An excitation drive control unit that outputs a drive signal corresponding to an excitation mode indicated by an instruction from the control unit;
A motor driver that excites a coil of each phase of the stepping motor based on a drive signal output from the excitation drive control unit;
When switching to the excitation mode indicated by the instruction from the control unit, the excitation drive control unit determines the excitation mode drive signal indicated by the instruction according to the combination of excitation modes before and after switching the excitation mode. A stepping motor excitation switching control device that outputs to the motor driver at a certain timing.

  According to this configuration, when switching the excitation mode of the stepping motor to the excitation mode indicated by the instruction from the control unit, the excitation drive control unit outputs the drive signal of the excitation mode indicated by the instruction of the control unit to the motor driver. Since the timing is adjusted to a predetermined timing according to the combination of each excitation mode before and after switching the excitation mode, the peak interval of the motor current waveform when switching the excitation mode can be kept constant. It is possible to keep the motor current waveform of each excitation mode in a waveform close to a sine wave.

The invention according to claim 2 is the stepping motor excitation switching control device according to claim 1, wherein the excitation drive control unit is predetermined for a combination of excitation modes before and after the switching. An output timing storage table for storing the output timing of the drive signal;
When the excitation drive control unit switches the excitation mode in accordance with the switching instruction from the control unit, the output timing storage of the drive signal output timing predetermined for each combination of excitation modes before and after the switching at that time The excitation mode drive signal indicated by the switching instruction is output to the stepping motor at the read output timing from the table.

  According to this configuration, when the excitation drive control unit switches the excitation mode in accordance with the switching instruction from the control unit, the output timing of the drive signal determined in advance for each combination of excitation modes before and after the switching at that time is set. Since the excitation mode drive signal indicated by the switching instruction is output to the stepping motor at the output timing read from the output timing storage table, the peak interval of the motor current waveform when switching the excitation mode can be kept constant. The motor current waveform in each excitation mode before and after switching the excitation mode can be kept at a waveform close to a sine wave.

The invention according to claim 3 is the stepping motor excitation switching control device according to claim 1, wherein the excitation drive control unit generates A-phase and B-phase motor clock signals to be output to the stepping motor. The motor clock signal generation unit, the current controller generation unit for generating the A-phase and B-phase current controllers to be output to the stepping motor, and the clock to be supplied to the motor clock signal generation unit and the current controller generation unit, A clock oscillating unit that oscillates with a half cycle of the motor clock signal generated by the motor clock signal generating unit,
The current controller generating unit outputs current to the stepping motor based on a clock oscillated from the clock oscillation unit when switching from the two-phase excitation mode to the 1-2 phase excitation mode in accordance with a switching instruction from the control unit. The controller is output earlier than the motor clock signal generated by the motor clock signal generation unit by 1/2 clock of the motor clock signal.

  In the conventional technique, for example, assuming that the original peak interval of 1-2 phase excitation is 4 steps, when switching from the 2-phase excitation mode to the 1-2 phase excitation mode, the peak interval of 1-2 phase excitation immediately after the switching is According to the third aspect of the present invention, the stepping motor excitation mode is changed from the 2-phase excitation mode to the 1-2 phase excitation mode in accordance with the switching instruction from the control unit. When switching, as described above, the current controller generation unit outputs the current controller output to the stepping motor based on the clock oscillated from the clock oscillation unit to the motor clock signal generated by the motor clock signal generation unit. Therefore, the motor clock signal is output 1/2 clock earlier, so that the deviation like the above 0.5 step is eliminated, the excitation mode is smoothly switched, vibration, Generation of noise can be prevented.

According to a fourth aspect of the present invention, there is provided the stepping motor excitation switching control device according to any one of the first to third aspects,
A stepping motor whose excitation switching is controlled by the stepping motor excitation switching control device;
An image forming apparatus including a conveyance roller configured to convey a sheet using the stepping motor as a driving source.

According to a fifth aspect of the present invention, there is provided the stepping motor excitation switching control device according to any one of the first to third aspects,
A stepping motor whose excitation switching is controlled by the stepping motor excitation switching control device;
And an image forming unit having a rotating body that rotates using the stepping motor as a drive source.

  According to the first and second aspects of the present invention, the peak interval of the motor current waveform when switching the excitation mode can be kept constant, and the motor current waveform of each excitation mode before and after switching the excitation mode is changed to a sine wave. It is possible to keep a close waveform.

  According to the third aspect of the present invention, when the current controller generation unit switches the excitation mode of the stepping motor from the two-phase excitation mode to the 1-2 phase excitation mode according to the switching instruction from the control unit, the clock oscillation unit Based on the oscillated clock, the current controller to be output to the stepping motor is 1/5 of the motor clock signal corresponding to the deviation expected to be generated with respect to the motor clock signal generated by the motor clock signal generator. Since it is accelerated by 2 clocks, the deviation that occurred in the peak interval of 1-2 phase excitation after switching the excitation mode can be eliminated accurately, so that the excitation mode can be switched smoothly and the generation of vibration and noise can be prevented. It becomes possible to do.

  According to the invention described in claim 4 and claim 5, it is possible to obtain the effect of the invention described in any of claims 1 to 3.

  Hereinafter, a stepping motor excitation switching control device and an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing an internal configuration of a multifunction machine as an example of an image forming apparatus provided with a stepping motor excitation switching control device according to an embodiment of the present invention. The multifunction device 1 has functions such as a copy function, a printer function, a scanner function, and a facsimile function. The multi-function device 1 includes a main body 2, a stack tray 3 disposed on the left side of the main body 2, a document reading unit 5 disposed on the top of the main body 2, and an upper side of the document reading unit 5. And a document feeding unit 6 disposed.

  An operation unit 47 is provided at the front part of the multifunction machine 1. The operation unit 47 displays a start key 471 for a user to input a print execution instruction, a ten key 472 for inputting the number of copies to be printed, operation guide information for various copying operations, and the like. A display unit 473 formed of a liquid crystal display or the like having a touch panel function, a reset key 474 for resetting setting contents set in the display unit 473, and a stop key for stopping a printing (image forming) operation being executed 475 and a function switching key 477 for switching between a copy function, a printer function, a scanner function, and a facsimile function.

  The document reading unit 5 includes a scanner unit 51 including a CCD (Charge Coupled Device) sensor and an exposure lamp, and a document table 52 and a document reading slit 53 made of a transparent member such as glass. The scanner unit 51 is configured to be movable by a drive unit (not shown). When reading a document placed on the document table 52, the scanner unit 51 is moved along the document surface at a position facing the document table 52, and the document image is scanned. The image data acquired while scanning is output to the control unit 100. Further, when reading a document fed by the document feeding unit 6, the document is moved to a position facing the document reading slit 53 and synchronized with the document feeding operation by the document feeding unit 6 via the document reading slit 53. The image of the original is acquired and the image data is output to the control unit 100. The control unit 100 controls the overall operation of the multifunction machine 1, and in addition to the image data processing as described above, a paper transport mechanism including a paper feed roller 462, transport rollers 463, 464, 469, and the like. In addition, the operation of the recording unit (image forming unit) 40 is controlled. A part of the control unit 100 functions as the stepping motor excitation switching control device 10 (FIG. 2) according to an embodiment of the present invention.

  The document feeding unit 6 includes a document placement unit 61 for placing a document, a document discharge unit 62 for discharging a document whose image has been read, and a document placed on the document placement unit 61. A document transport mechanism 63 including a paper feed roller (not shown), a transport roller (not shown) and the like for feeding the paper one by one to a position facing the document reading slit 53 and discharging it to the document discharge section 62 is provided. The document conveyance mechanism 63 further includes a sheet reversing mechanism (not shown) that reverses the document and reversely conveys the document to a position facing the document reading slit 53, and scans both sides of the document through the document reading slit 53. 51 can be read.

  The document feeding unit 6 is provided so as to be rotatable with respect to the main body unit 2 so that the front side thereof can move upward. By moving the front side of the document feeder 6 upward to open the upper surface of the document table 52, the operator can place a read document, for example, a book in a spread state, on the upper surface of the document table 52. It has become.

  The main body 2 includes a plurality of paper feed cassettes 461, a paper feed roller 462 that feeds the recording paper from the paper feed cassette 461 one by one and transports it to the recording unit 40, and a recording paper transported from the paper feed cassette 461. And a recording unit 40 for forming an image.

  The recording unit 40 outputs an optical beam or the like based on the image data acquired by the scanner unit 51 to expose the photosensitive drum 43, and a developing unit 44 that forms a toner image on the photosensitive drum 43. A transfer unit 41 for transferring the toner image on the photosensitive drum 43 to the recording paper, a fixing unit 45 for fixing the toner image to the recording paper by heating the recording paper to which the toner image has been transferred, Conveying rollers 463 and 464 that are provided in the sheet conveying path and convey the recording sheet to the stack tray 3 or the discharge tray 48 are provided.

  When forming images on both sides of the recording paper, the recording unit 40 forms an image on one side of the recording paper, and then the recording paper is nipped by the conveyance roller 463 on the discharge tray 48 side. . In this state, the conveyance roller 463 is reversed to switch back the recording paper, and the recording paper is sent to the paper conveyance path L and conveyed again to the upstream area of the recording unit 40, and an image is formed on the other surface by the recording unit 40. Thereafter, the recording paper is discharged to the stack tray 3 or the discharge tray 48.

  Next, a stepping motor excitation switching control device according to an embodiment of the present invention will be described. FIG. 2 is a diagram showing a schematic configuration of a stepping motor excitation switching control device according to an embodiment of the present invention. The stepping motor excitation switching control device 10 (hereinafter, device 10) controls the driving of the stepping motor 16 and performs switching control of the excitation mode of the stepping motor 16. The apparatus 10 is configured by a part of the control unit 100 as described above.

  The apparatus 10 includes a CPU 11, a ROM 12, a RAM 13, a logic circuit 14, and a motor driver 15.

  The CPU (control unit) 11 controls the overall operation of the apparatus 10 and switches and controls the excitation mode of the stepping motor 16. The ROM 12 stores a system program for operation control of the entire apparatus 10 and the like. The RAM 13 is used by the CPU 11 as a work area for operations based on the system program stored in the ROM 12.

  The logic circuit (excitation drive control unit) 14 is a circuit that generates logic for driving the motor driver 15. The motor driver 15 includes an excitation circuit that determines the excitation order and a drive circuit that controls the power supplied to the stepping motor 16, and drives the stepping motor 16 by outputting a drive pulse to the stepping motor 16. The stepping motor 16 is a synchronous motor that operates in synchronization with a drive pulse (pulse power) from the motor driver 15.

  FIG. 3 is a diagram illustrating an example of the configuration of the logic circuit 14. The logic circuit 14 includes a motor clock signal generation unit 141, a current controller generation unit 143, a register unit 144, and a clock oscillation unit 145.

  The motor clock signal generation unit 141 generates A-phase and B-phase clocks to be output to the stepping motor 16 (motor driver 15) based on the clock from the clock oscillation unit 145. In this embodiment, the motor clock signal generation unit 141 generates a 1-2 phase excitation mode control circuit 141A that generates a motor clock signal for the 1-2 phase excitation mode and a motor clock signal for the 2 phase excitation mode. A two-phase excitation mode control circuit 141B.

  The current controller generation unit 143 generates the A phase and B phase current controllers of the stepping motor 16 based on the clock from the clock oscillation unit 145. In this embodiment, the current controller generation unit 143 generates a 1-2 phase excitation mode control circuit 143A that generates a current controller for the 1-2 phase excitation mode and a current controller for the two phase excitation mode. A two-phase excitation mode control circuit 143B.

  The register (I / O output port) 144 stores a setting by the CPU 11 for operating the stepping motor 16 in the 1-2 phase excitation mode or the two phase excitation mode. The register unit 144 outputs a signal indicating the set excitation mode to the motor clock signal generation unit 141 and the current controller generation unit 143.

  The clock oscillator 145 generates a clock signal (synchronization signal) to be output to each of the motor clock signal generator 141 and the current controller generator 143. The clock oscillation unit 145 generates a clock having a period (double frequency) of a half of each of the A phase and B phase motor clock signals output from the motor clock signal generation unit 141 to the stepping motor 16 and oscillates To do.

  Next, the excitation mode switching control from the two-phase excitation mode to the 1-2 phase excitation mode by the stepping motor excitation switching control device 10 will be described. FIG. 4 is a flowchart showing a process at the time of excitation mode switching control from the 2-phase excitation mode to the 1-2 phase excitation mode, and FIG. 5 shows control signal patterns at the time of switching the excitation mode from the 2-phase excitation to the 1-2 phase excitation. It is a figure which shows a motor current waveform. In FIG. 5, CLK A and CLK B indicate motor clock signals applied to the A phase and the B phase, respectively, I0 and I1 indicate an A phase current controller, and I2 and I3 indicate a B phase current controller.

  For example, when the stepping motor 16 is operated in the two-phase excitation mode, the CPU 11 sets the register unit 144 to indicate the two-phase excitation mode operation (S1). When the register unit 144 is set for the two-phase excitation mode operation, the motor clock signal generation unit 141 and the current controller generation unit 143 receive the signal indicating the two-phase excitation mode output from the register unit 144, respectively. The signal lines are switched to connect the internal control circuit to the two-phase excitation mode control circuits 141B and 143B (S2). Then, the two-phase excitation mode control circuit 141B of the motor clock signal generation unit 141 outputs a motor clock signal to the motor driver 15, and the two-phase excitation mode control circuit 143B of the current controller generation unit 143 supplies a current controller to the motor driver 15. Is output (S3). The motor clock signal generation unit 141 and the current controller generation unit 143 store in the built-in unillustrated storage unit that the excitation mode to be operated from now is the two-phase excitation mode (S4). Thereafter, the stepping motor 16 starts operating in the two-phase excitation mode (S5). Actually, the operation of the stepping motor 16 requires through-up and through-down operations, but the description is omitted because it is not directly related to this case.

  When the CPU 11 determines that it is necessary to switch the excitation mode to the 1-2 phase excitation mode using, for example, the switching of the driving force transmission destination of the stepping motor 16 as a trigger (YES in S6), the CPU 11 The unit 144 is set to indicate the 1-2 phase excitation mode operation (S7). When receiving a signal indicating the 1-2 phase excitation mode output from the register unit 144, the motor clock signal generation unit 141 and the current controller generation unit 143 receive the 1-2 phase based on the storage contents of the storage unit. The excitation mode before switching to the excitation mode is detected (S8).

  Here, the motor clock signal generation unit 141 and the current control unit generation unit 143 are arranged at a timing determined in advance according to the excitation mode before switching stored in the storage unit. The control circuit in the child generator 143 is switched to the 1-2 phase excitation mode control circuit 141A, 143A. The predetermined switching timing is stored in an output timing storage table in a storage area (not shown) in the logic circuit 14, and the motor clock signal generation unit 141 and the current controller generation unit 143 are output from the register unit 144. When a signal indicating the 1-2 phase excitation mode is received, a predetermined switching timing is read from the output timing storage table.

  In this embodiment, when the excitation mode before switching to the 1-2 phase excitation mode is the two-phase excitation mode, the predetermined timing is determined by the control circuit in the current controller generation unit 143. The timing of switching to the 1-2 phase excitation mode control circuit 143A is higher than the timing of switching the control circuit in the motor clock signal generation unit 141 to the 1-2 phase excitation mode control circuit 141A. The timing is set earlier by one clock (that is, 1/2 clock of the motor clock signal generated by the motor clock signal generation unit 141).

  In the present embodiment, since the excitation mode before switching to the 1-2 phase excitation mode is the two phase excitation mode, the current controller generation unit 143 changes the internal control circuit according to the predetermined switching timing. The motor clock signal generation unit 141 switches to the 1-2 phase excitation mode control circuit 143A first (S9), and the clock signal output from the clock oscillation unit 145 is determined from the control circuit switching timing by the current controller generation unit 143. With a delay of one clock, the motor clock signal generation unit 141 switches the internal control circuit to the 1-2 phase excitation mode control circuit 141A (S10).

  As a result, the current controller for the 1-2 phase excitation mode is output from the 1-2 phase excitation mode control circuit 143A of the current controller generation unit 143, and the clock signal of the clock oscillation unit 145 is delayed by one clock. The motor clock signal for the 1-2 phase excitation mode is output from the 1-2 phase excitation mode control circuit 141A of the motor clock signal generation unit 141, and the stepping motor 16 starts operating in the 1-2 phase excitation mode ( S11).

  By performing the processing in this manner, as shown in FIG. 5, when switching from the two-phase excitation mode to the 1-2 phase excitation mode, the peak intervals of the motor current waveforms of the A phase and the B phase are changed to the two-phase excitation mode. Before and after switching to the 1-2 phase excitation mode, 4 steps (motor clock signal 4CLK) are maintained, and the motor current waveform is kept close to an ideal sine wave. As a result, it is possible to prevent vibration and noise of the stepping motor 16 caused by fluctuations in the peak intervals of the A-phase and B-phase motor current waveforms.

  That is, at the conventional switching timing shown in FIG. 6, the motor clock signal generator 141 and the current controller generator 143 do not perform the processes of S8 to S10 shown in FIG. When switching to the two-phase excitation mode, the peak interval of the A-phase and B-phase motor current waveforms fluctuated from 4 steps before switching to 4.5 steps, and this caused vibration and noise of the stepping motor 16. However, in the embodiment of the present invention shown in FIG. 4, as indicated by an arrow in FIG. 5, the 1-2 phase excitation of the current controller generation unit 143 is advanced one clock earlier than the clock signal of the clock oscillation unit 145. Since the current controller for the 1-2 phase excitation mode is output from the mode control circuit, the fluctuation of the peak interval of the motor current waveform, which has been conventionally seen, is prevented, and the stepping motor 16 vibrations and noises are prevented.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, in the above embodiment, FIGS. 4 and 5 show the control at the time of switching from the 2-phase excitation mode to the 1-2 phase excitation mode, but the present invention is not limited to this control. For example, the output timing storage table in the logic circuit 14 stores the current controller and the output timing of the motor clock signal determined in advance for each combination of excitation modes before and after switching, and the current controller generator 143. When the motor clock signal generation unit 141 switches the excitation mode according to the switching instruction from the CPU 11, the internal control circuit is set to 1 at an output timing predetermined for each combination of excitation modes before and after the switching at that time. The current controller and the motor clock signal may be output to the motor driver 15 and the stepping motor 16 by switching to the two-phase excitation mode control circuits 143B and 141B.

  In the case of the above embodiment, when switching from the 2-phase excitation mode to the 1-2 phase excitation mode, the motor clock signal generation unit 141 and the current controller generation unit 143 are obtained from the output timing storage table in the logic circuit 14. The predetermined switching timing is read out, and the internal control circuit is switched to the 1-2 phase excitation mode control circuits 143B and 141B at the predetermined switching timing. The excitation mode switching timing control is as follows. You may do as follows.

  For example, a register unit 144A that stores settings for the motor clock signal generation unit 141 and a current controller generation unit 143 as to whether the register unit 144 performs the operation in the two-phase excitation mode or the 1-2 phase excitation mode. Are configured to include two registers of the register unit 144B for storing the settings for the first time. When the CPU 11 determines that it is necessary to switch the excitation mode from the two-phase excitation mode to the 1-2 phase excitation mode, based on the clock signal from the clock oscillating unit 145, the CPU 11 The register unit 144B that stores the setting is set to indicate the 1-2 phase excitation mode earlier than the register unit 144A that stores the setting for the motor clock signal generation unit 141 by one clock of the clock signal output from the clock oscillation unit 145. And Then, the CPU 11 stores the register unit 144A for storing the setting for the motor clock signal generation unit 141 when one clock of the clock signal output from the clock oscillation unit 145 has elapsed since the setting of the register unit 144B. Set to indicate phase excitation mode. According to this, when switching from the 2-phase excitation mode to the 1-2 phase excitation mode, the motor clock signal generation unit 141 and the current controller generation unit 143 are determined in advance from the output timing storage table in the logic circuit 14. There is no need to read the switching timing and control the switching timing of the internal control circuit.

  Further, the stepping motor excitation switching control device and the image forming apparatus according to the present invention are not limited to the stepping motor excitation switching control device 10 and the multifunction device 1 shown in the configuration and processing of FIGS. Configuration and processing are merely examples.

  The image forming apparatus according to the present invention is not limited to a multifunction machine, and may be another image forming apparatus such as a copying machine or a facsimile machine.

1 is a side view showing an internal configuration of a multifunction machine that is an example of an image forming apparatus including a stepping motor excitation switching control device according to an embodiment of the present invention. It is a figure which shows schematic structure of the stepping motor excitation switching control apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of a structure of a logic circuit. It is a flowchart which shows the process at the time of the excitation mode switching control from 2 phase excitation mode to 1-2 phase excitation mode. It is a figure which shows the control signal pattern and motor current waveform at the time of the excitation mode switch from 2 phase excitation to 1-2 phase excitation. It is a figure which shows the control signal pattern and motor current waveform at the time of the excitation mode switch from the conventional 2-phase excitation to 1-2 phase excitation. The control signal pattern and motor current waveform given to the motor driver at the time of two-phase excitation and 1-2 phase excitation are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunction machine 10 Stepping motor excitation switching control apparatus 100 Control part 14 Logic circuit 141 Motor clock signal generation part 141A 1-2 phase excitation mode control circuit 141B Two phase excitation mode control circuit 143 Current controller generation part 143A 1-2 phase excitation Mode control circuit 143B Two-phase excitation mode control circuit 144 Register unit 144A Register 144B Register 145 Clock oscillation unit 15 Motor driver 16 Stepping motor 40 Recording units 463, 464, 469 Transport rollers

Claims (5)

A control unit that switches and controls the excitation mode of the stepping motor;
An excitation drive control unit that outputs a drive signal corresponding to an excitation mode indicated by an instruction from the control unit;
A motor driver that excites a coil of each phase of the stepping motor based on a drive signal output from the excitation drive control unit;
When switching to the excitation mode indicated by the instruction from the control unit, the excitation drive control unit determines the excitation mode drive signal indicated by the instruction according to the combination of excitation modes before and after switching the excitation mode. A stepping motor excitation switching control device that outputs to the motor driver at a timing. The excitation drive control unit has an output timing storage table for storing the output timing of the drive signal determined in advance for each combination of excitation modes before and after the switching,
When the excitation drive control unit switches the excitation mode in accordance with the switching instruction from the control unit, the output timing storage of the drive signal output timing predetermined for each combination of excitation modes before and after the switching at that time The stepping motor excitation switching control device according to claim 1, wherein the stepping motor excitation switching control device outputs the excitation mode drive signal indicated by the switching instruction to the stepping motor at the read output timing from the table. The excitation drive control unit includes a motor clock signal generation unit that generates A-phase and B-phase motor clock signals to be output to the stepping motor, and a current control that generates A-phase and B-phase current controllers to be output to the stepping motor. And a clock oscillation unit that oscillates a clock to be supplied to the motor clock signal generation unit and the current controller generation unit with a cycle that is 1/2 of the motor clock signal generated by the motor clock signal generation unit. And
The current controller generating unit outputs current to the stepping motor based on a clock oscillated from the clock oscillation unit when switching from the two-phase excitation mode to the 1-2 phase excitation mode in accordance with a switching instruction from the control unit. 2. The stepping motor excitation switching control device according to claim 1, wherein the controller is output earlier than the motor clock signal generated by the motor clock signal generation unit by 1/2 clock of the motor clock signal. A stepping motor excitation switching control device according to any one of claims 1 to 3,
A stepping motor whose excitation switching is controlled by the stepping motor excitation switching control device;
An image forming apparatus comprising: a conveyance roller configured to convey a sheet using the stepping motor as a driving source. A stepping motor excitation switching control device according to any one of claims 1 to 3,
A stepping motor whose excitation switching is controlled by the stepping motor excitation switching control device;
An image forming apparatus comprising: an image forming unit having a rotating body that rotates using the stepping motor as a driving source.

Images