JPH07245990A - Stepping motor driver - Google Patents

Abstract

PURPOSE:To provide a simple-structured and low-cost stepping motor driver which lightenes a burden of data processing of a microprocessor (CPU) for controlling the motor without dropping a processing speed of the processor. CONSTITUTION:A pulse rate in a motor accelerating area which is written in an interrupt handling timer 3 when an output signal of a CPU 1 is sent out is rewritten each time an interruption is requested by a timer counter. In a timer for setting a motor constant speed area 6, a pulse rate in a motor constant speed area is written. Based on a command from the CPU 1, a signal is selected from the timer 3 in the accelerating area and from the timer for setting a motor constant speed area 6 after the speed reaches the constant speed area and thereby a pulse for exciting a motor is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor driving device mounted on a laser printer, a facsimile, a copying machine or the like and controlled by a microprocessor.

[0002]

2. Description of the Related Art Conventionally, a step motor has been generally used as a drive source for conveying a sheet and driving a photosensitive drum in a device such as a laser printer or a facsimile, and a dedicated micro controller is used to drive and control the step motor. It is known that a processor is used, a device control microprocessor is also used for driving a motor, and a microprocessor having a step motor dedicated port is used.

[0003]

However, when a dedicated microprocessor is used, the cost of the entire device is increased accordingly, and when a device control microprocessor is commonly used for driving a motor, a printer has been recently used. The speed of data processing is slowed down because the program processing speed by the microprocessor has reached the limit of the program processing speed. There is. Further, when a microprocessor having a dedicated port is used, the processing speed does not decrease, but such a processor becomes expensive. Further, it is known to reduce the data processing load of the microprocessor by switching the control mode between the acceleration drive range and the constant speed drive range of the motor, but the configuration for that becomes complicated,
It was not easy to change the design specifications.

The present invention has been made in order to solve the above-mentioned problems, and in a device using a device controlling microprocessor for driving a motor, the load of data processing of the microprocessor can be reduced and the processing thereof can be reduced. It is an object of the present invention to provide a step motor drive device that has a simple structure and can be manufactured at a low cost with almost no decrease in speed.

[0005]

In order to achieve this object, the invention of claim 1 is a step motor drive device in which a control mode is switched between an acceleration drive range and a constant speed drive range of a motor. And a microprocessor capable of processing data other than the driving, and a pulse rate in the motor acceleration region is written based on an output signal from the microprocessor, and the pulse rate is rewritten each time an interrupt request is generated by a timer count. A timer,
A constant speed region setting timer, which is independent of the interrupt processing timer, in which the pulse rate in the motor constant speed region is written based on the output signal from the microprocessor, and driving pulses are supplied to both timers independently. Based on the clock source and the instruction from the microprocessor, the selector selects the signal from the interrupt processing timer in the acceleration range and the signal from the constant speed range setting timer after reaching the constant speed range. , And an excitation pulse generation circuit that generates a motor excitation pulse based on the signal selected by the selector. According to a second aspect of the present invention, in the step motor drive device according to the first aspect, the interrupt processing timer causes the microprocessor to perform interrupt processing for data processing other than driving the motor outside the acceleration range of the motor. Can be controlled.

[0006]

According to the step motor drive apparatus of the present invention having the above structure, the interrupt processing timer is written with a pulse rate in the motor acceleration region based on the output signal from the microprocessor, and the pulse rate is counted by the timer. It is rewritten every time an interrupt request occurs. The excitation pulse generation circuit gradually accelerates the step motor every time the pulse rate is rewritten, based on the signal from the interrupt processing timer. When the step motor reaches the constant speed range, the selector selects the signal of the constant speed range setting timer from the interrupt processing timer signal based on the instruction from the microprocessor. The constant speed region setting timer is supplied with a drive pulse from a clock source independently of the interrupt processing timer, and based on a command from the microprocessor,
The pulse rate in the motor constant speed region is written, and the step motor is driven at constant speed. Since the pulse rate in the constant speed region has a constant cycle, it is written only once. In the step motor drive device according to the second aspect of the present invention, the interrupt processing timer performs, for the microprocessor, interrupt processing for data processing other than driving the motor outside the acceleration region of the motor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block configuration diagram of a step motor drive device mounted on a laser printer for carrying a sheet and driving a photosensitive drum. A microprocessor (hereinafter, referred to as CPU) 1 is a motor drive and a printer. Performs various processing operations. The program and data of the CPU 1 are stored in the ROM 2 and the RAM (not shown),
The transfer of the program and data is performed via the system bus. The ROM 2 stores a table of pulse rates in the motor acceleration range and the constant speed range.

The interrupt processing timer 3 receives the write signal WR and the data signal DATA (timer time) from the CPU 1 and receives an interrupt signal TM1INT for issuing an interrupt request to the CPU 1 at predetermined intervals (for example, 10 ms).
Outputs / (/ means low and active). The interrupt processing timer 3 has a write signal WR and a data signal DA.
The pulse rate in the motor acceleration range is written by TA,
This pulse rate is rewritten each time an interrupt request is generated by the timer count. The interrupt processing timer 3 makes an interrupt request for data processing other than driving of the motor to the CPU 1 outside the motor acceleration range, and the CPU 1 performs the interrupt processing by, for example, a sensor that detects the internal temperature of the device. Check the signal of.

The motor controller 4 outputs an A, B, A /, B / phase drive pulse to the step motor 5 as an AS.
IC (Application Specific IC, ASIC),
Write signal WR and data signal DATA from CPU1
(Timer time) is written to the motor constant speed range setting timer 6, a selector 7 for switching and selecting a signal between an acceleration range and a constant speed range based on a timer switching signal SHSEL of the CPU 1, and a selector 7 selected by the selector 7. Motor drive pulses PMA, PMB, PMA /, PMB / based on the signal
And an excitation pulse generation circuit 8 for generating

The pulse rate in the motor constant speed region is written in the motor constant speed region setting timer 6 by the write signal WR and the data signal DATA. As the timer switching signal of the CPU 1 for the selector 7, the interrupt signal TM1INT / of the interrupt processing timer 3 is selected in the acceleration region of the motor, and the output signal FCUP of the constant period from the motor constant velocity region setting timer 6 is selected in the constant velocity region. select. The CPU 1 also causes the excitation pulse generation circuit 8 to output the motor enable signal PMEN.
give. The interrupt processing timer 3 is provided separately from the motor controller 4, that is, independently of the constant speed region setting timer 6, and the timers 3 and 6 are independently provided to the CPU 1. The clock pulse CLK is supplied from an internal or external clock source.

Next, the operation of the driving device having the above structure will be described with reference to FIGS. 2 and 3. FIG. 2 is a flowchart showing the processing from the acceleration of the motor to the constant speed driving,
FIG. 3 is a time chart of signals of respective parts at that time. After setting a preset value (for example, 10 ms for key scan) in the interrupt processing timer 3, the CPU 1 writes the constant speed region pulse rate in the motor constant speed region setting timer 6 (S1), and thereafter, The timer switching signal SHSEL (high) is output to the selector 7, and thereby the interrupt processing timer 3 is selected (S2). Then, the acceleration region pulse rate is written in the interrupt processing timer 3 (S3), and further, the motor enable signal PMEN is output to enable the motor output (S4).

When the interrupt processing timer 3 counts up, an interrupt signal TM1INT /
The CPU 1 rewrites the pulse rate of the interrupt processing timer 3 by this interrupt processing (S6). CP
U1 checks whether the motor speed has reached the constant speed range, that is, a predetermined pulse rate written in the motor constant speed range setting timer 6 in advance (S7).
Repeat the loop of 5 to S7. In the acceleration region pulse rate, the interrupt signal TM1INT / has the pulse interval gradually shortened as shown in FIG. By such software processing, the interrupt signal TM1I corresponding to the acceleration region pulse rate
Based on NT /, the excitation pulse generation circuit 8 generates motor drive pulses PMA, PMB, PMA /, PMB /, and thereby the motor 5 is accelerated.

When the motor speed reaches the constant speed range, the CPU
1 outputs a timer switching signal SHSEL (low) to the selector 7 to select the motor constant speed region setting timer 6 (S
8) At the same time, the interrupt processing timer 3 is returned to the initial setting value (10 ms for key scanning) (S
9) and then return to the normal process (S10). Since the motor constant speed region setting timer 6 is selected in S8, the excitation pulse generating circuit 8 is provided with the output signal FCUP of a constant cycle, whereby the motor 5 is driven at a constant speed. In this way, after the motor speed reaches the constant speed range, the motor is
Instead of the software processing by 1, the rotation is driven only by the hardware by the motor constant speed range setting timer 6, so that the processing load on the CPU 1 is reduced and the processing speed does not decrease. Further, after the motor speed reaches the constant speed range, the interrupt processing timer 3 is set to the CPU 1
For example, interrupt signal TM1INT /
To perform other processing, for example, temperature detection processing by a temperature sensor. When the CPU 1 receives a signal to stop the motor from a sensor or the like, it outputs the signal from the interrupt processing timer 3 to the selector 7 so as to select it, and then writes the deceleration pulse rate to the interrupt processing timer 3. . After that, the CPU 1 rewrites the pulse rate every time the interrupt signal TM1INT is input from the interrupt processing timer 3, and decelerates the motor.

Further, since the interrupt processing timer 3 is provided independently of the motor constant speed region setting timer 6 and is provided outside the motor controller 4, the respective timer configurations are simplified, and the design and specifications are made. Can be changed easily, and the cost of the motor controller 4 can be reduced. The present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made.

[0015]

As described above, according to the step motor driving apparatus of the first aspect, the interrupt processing timer in which the pulse rate in the motor acceleration range is rewritten by the microprocessor every time an interrupt request is generated, and the pulse in the motor constant speed range are provided. By using the constant speed region setting timer in which the rate is written, the motor is driven in the acceleration drive region by software and in the constant speed drive region by hardware, so that the data processing load of the microprocessor is reduced, Since the processing speed does not decrease and both timers are provided independently, the structure is simple and the cost can be reduced. According to the step motor driving device of the second aspect, the interrupt processing for data processing other than driving the motor is controlled to the microprocessor by one interrupt processing timer outside the acceleration region of the motor. The timer can be used efficiently.

[Brief description of drawings]

FIG. 1 is a block diagram of a stepping motor driving device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure for driving a motor in the same apparatus.

FIG. 3 is a time chart when the motor is driven in the device.

[Explanation of symbols]

 1 Microprocessor (CPU) 3 Timer for interrupt processing 5 Step motor 6 Timer for motor constant speed range setting 7 Selector 8 Excitation pulse generation circuit

Claims (2)

[Claims] 1. A stepping motor drive device in which a control mode is switched between an acceleration drive range and a constant speed drive range of a motor, a microprocessor capable of performing motor drive and data processing other than the drive, and a microprocessor A pulse rate in the motor acceleration range is written based on the output signal of the motor, and the pulse rate is rewritten each time an interrupt request is generated by a timer count; and a constant speed motor range based on the output signal from the microprocessor. A constant speed region setting timer independent of the interrupt processing timer, a clock source for supplying a driving pulse to each of the timers independently, and a command from the microprocessor. In the acceleration range, select the signal from the interrupt processing timer to reach the constant speed range. After that, a selector for selecting a signal from the constant speed region setting timer, and an excitation pulse generation circuit for generating a pulse for motor excitation based on the signal selected by the selector are provided. Step motor drive device. 2. The step motor drive device according to claim 1, wherein the interrupt processing timer causes the microprocessor to perform interrupt processing for data processing other than driving the motor outside the acceleration range of the motor. A step motor drive device characterized by being capable of controlling.