JP2000299998A - Drive equipment for stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive equipment for a stepping motor, capable of preventing occurrence of burnout accidents. SOLUTION: In a drive equipment 1 for a stepping motor, a phase signal monitoring timer 30 monitors A-phase, B-phase, C-phase, and D-phase signals which are output from a CPU 13, and when a prescribed constant time has passed from a change in the phase signal to a subsequent change in the phase signal, an error signal is output to the base of a switching element 31. When a switching element 31 turns on by this error signal, H-level signals output from AND-circuits 25, 26, 27, 28 are canceled and motor drivers 6, 7, 8, 9 are turned off, so that the drive of stepping motor is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stepping motor driving device for driving a stepping motor.

[0002]

2. Description of the Related Art A stepping motor is driven by controlling the energization of each motor coil of the stepping motor by a motor driver. The motor driver is turned on and off by a phase signal generated by a microcomputer, a gate array, or the like.

[0003]

However, there are cases where the phase signal remains active due to factors such as mistakes in the microcomputer program, static electricity, and noise. If this state is left unattended, the motor coil and the motor driver may overheat, causing a burnout accident.

An object of the present invention is to provide a stepping motor drive device capable of preventing occurrence of a burnout accident.

[0005]

According to a first aspect of the present invention, there is provided a motor driver for driving a stepping motor by controlling energization of a motor coil, and turning on and off the motor driver by supplying a phase signal. A phase signal supply device, a detection device for detecting a change in the phase signal, and a counting device for counting whether or not a preset time has elapsed between the occurrence of the change and the next occurrence of the change. And a stop device for turning off the motor driver when the time has elapsed.

Accordingly, when the phase signal does not change within a preset time, the motor driver is stopped and the stepping motor is stopped, so that the occurrence of burnout accident can be prevented.

[0007]

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

In FIG. 1, reference numerals 2, 3, 4, and 5 denote motor coils of a stepping motor, one end of which is connected to a 24V power supply. Symbols 6, 7, 8, 9
Are motor drivers which are constituted by switching elements and control the energization of the motor coils 2, 3, 4 and 5 to drive the stepping motor. The collector of each of the motor drivers 6, 7, 8, 9 is connected to the other end of the motor coil 2, 3, 4, or 5, and the emitter is connected to GND via the resistor 10 or 11.

The microcomputer circuit 12 includes a CPU 13 for centrally controlling each unit of the stepping motor driving device 1, a ROM 14 storing various programs and the like, and a rewritable memory R for storing data.
AM 15 is connected by bus 16. CPU1
3 generates and outputs phase signals of phase A, phase B, phase C and phase D of the stepping motor, and outputs the phase signals of the motor drivers 6, 7, 8,
9 is also provided with a function as a pattern generator for driving on and off. Thereby, the CPU 13 has a function of a phase signal supply device.

The current setting circuit 17 includes a motor coil 2,
This sets the magnitude of the current flowing through 3, 4, and 5.
The circuit configuration is as follows. That is, the current switching port 18 is formed of a gate array, is connected to the bus 16, and outputs an H level signal or an L level signal from the MCC1 terminal and the MCC2 terminal, respectively. The resistors 19, 20, 21 and 22 are connected in series,
The end of the resistor 19 is connected to a 5V power supply, and the end of the resistor 22 is connected to G
Connected to ND. The switching element 37 has a collector connected to the line between the resistors 20 and 21, an emitter connected to GND, and a base connected to the MCC1 terminal. The switching element 38 has a collector 21
, The emitter is connected to GND, and the base is connected to the MCC2 terminal. Each of the comparator circuits 23 and 24 has its non-inverting input terminal connected to the line between the resistors 19 and 20, and the inverting input terminal of the comparator circuit 23 receiving the terminal voltage of the resistor 10, The terminal voltage of the resistor 11 is input to the input terminals. AND circuit 25,
A, B, C or D phase signals are input to 26, 27 and 28, respectively.
Alternatively, 24 output signals are input. AND circuit 25,
Outputs of motor drivers 26, 27, and 28 are respectively
It is input to the base of 7, 8, or 9.

The phase signal monitoring circuit 29 monitors a phase signal output from the CPU 13, and has the following circuit configuration. That is, the phase signal monitoring timer 30 is constituted by a gate array, connected to the bus 16,
A-phase, B-phase, C-phase, and D-phase signals output from U13 are input. Then, the phase signal monitoring timer 30 detects a change in the phase signal, and turns on the timer when the phase signal changes. When a predetermined time has elapsed since the timer was turned on, the phase signal monitoring timer 30 outputs a predetermined error signal. However, if the phase signal changes again before the fixed time has elapsed, the timer is reset. The phase signal monitoring timer 30 has a function as a detecting device and a counting device. The switching element 31 is connected to the base via the resistor 32 so that the error signal is input, the emitter is connected to a power supply of 5 V, and the collector is connected to the resistor 33, 34, 35 or 3
6 and is connected to the output terminal of the AND circuit 25, 26, 27 or 28. The switching element 31 has a function as a stop device.

The operation of the stepping motor driving device 1 having the above-described circuit configuration will be described. First, the magnitude of the input voltage to the non-inverting input terminals of the comparator circuits 23 and 24 is changed depending on whether the output signals of the MCC1 terminal and the MCC2 terminal of the current switching port 18 are set to H level or L level. be able to. That is, M
When the output voltage of both the CC1 terminal and the MCC2 terminal is set to L level, the input voltage to the comparator circuits 23 and 24 becomes large. If the output voltage of both the MCC1 terminal and the MCC2 terminal is set to the H level, the input voltage to the comparator circuits 23 and 24 becomes small. If the output voltage of the MCC1 terminal is set to L level and the output voltage of the MCC2 terminal is set to H level, the input voltage to the comparator circuits 23 and 24 becomes medium.

The comparator circuits 23 and 24 compare the large, medium or small input voltage with the terminal voltage of the resistor 10 or 11, and output a signal corresponding to the comparison result. This output signal is supplied to an AND circuit 25,
26, 27 and 28. AND circuit 25, 2
6, 27, 28 take the AND of the A-phase, B-phase, C-phase, or D-phase signal and the output signal of the comparator circuit 23 or 24 and output the result to the base of the motor driver 6, 7, 8, 9 By doing so, the phase signal of the A phase, B phase, C phase or D phase is chopped. As a result, a constant current having a magnitude corresponding to the magnitude of the input voltage to the non-inverting input terminals of the comparator circuits 23 and 24 is supplied to the motor coils 2, 3, 4, and 5. That is, the comparator circuits 23 and 24 become constant current chopper circuits.

FIG. 2 is a flowchart for explaining the operation of the microcomputer circuit 12. As shown in FIG. 2, first, C
The PU 13 determines whether or not the stepping motor drive device 1 is in the drive current setting (step S1). In the drive current setting, the CPU 13 sets the motor coils 2, 3,
The current setting circuit 17 sets the magnitude of the current to be supplied to 4, 5 to large or medium, and drives the stepping motor.

When the drive current is set (step S
1) Y), the CPU 13 starts the phase signal monitoring timer 30 (step S2). As a result, the phase signal monitoring timer 30 monitors the phase signal output by the CPU 13 and, when a predetermined period of time elapses from the phase signal change to the next phase signal change, outputs the error signal to the switching element. 31 to the base. When the switching element 31 is turned on by this error signal, the AND circuit 25,
Since the H-level signals output by 26, 27, and 28 are canceled and the motor drivers 6, 7, 8, and 9 are turned off, the driving of the stepping motor stops. That is, when a predetermined period of time has elapsed after the phase signal has changed and the phase signal has not changed, the phase signal remains active and the motor coil 2, 3, 4 or 5 or the motor coil In this case, there is a possibility that the driver 6, 7, 8 or 9 may overheat and cause a burnout accident.
By stopping the stepping motor, it is possible to prevent the occurrence of burnout accident.

If it is determined in step S1 that the stepping motor driving device 1 is not in the drive current setting (N in step S1), the weak current hold is set (step S3). In the weak current hold, the CPU 13 sets the magnitude of the current flowing through the motor coils 2, 3, 4, and 5 to a small value by the current setting circuit 17. In the weak current hold, since the phase signal does not change, the phase signal monitoring timer 30 is not started, so that the error signal is not output from the phase signal monitoring timer 30.

[0017]

According to the present invention, when the phase signal does not change within a preset time, the motor driver is stopped and the stepping motor is stopped, so that the occurrence of burnout accident can be prevented. it can.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an operation of a microcomputer circuit of the stepping motor driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stepping motor drive device 2 Motor coil 3 Motor coil 4 Motor coil 5 Motor coil 6 Motor driver 7 Motor driver 8 Motor driver 9 Motor driver 13 Phase signal supply device 30 Detection device, counting device 31 Stop device

Claims (1)

[Claims] 1. A motor driver for controlling energization of a motor coil to drive a stepping motor; a phase signal supply device for supplying a phase signal to drive the motor driver on and off; A detecting device for detecting, a counting device for counting whether or not a preset time elapses from the change to the next change, and the motor driver when the time has elapsed And a stopping device for turning off the stepping motor.