JPS6248297A - Drive circuit for stepping motor - Google Patents

Abstract

PURPOSE:To select phase excitation, such as 2-phase one, 1-2-phase one and double 1-2-phase one extremely simply by changing a signal inputted to a ROM into an excitation system changeover signal. CONSTITUTION:A pulse input is converted into a 4-bit signal by a counter 1, an address in a ROM 2 is set by the 4-bit signal, and a corresponding data is outputted. Partial bits AD5, AD6 in addresses in the ROM 2 are used as inputs to excitation system changeover signals (a), (b). Three kinds of a 2-phase excitation signal pattern, a 1-2-phase excitation signal pattern and a double 1-2-phase excitation signal pattern are stored in the ROM 2 as data, and three kinds of the patterns are selected by the combination of 'H' and 'L' of the excitation system changeover inputs.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field 1 The present invention relates to a drive circuit for a 1-2 phase excitation force type step motor.

[Background Art 1] A step motor can make the step angle 1/211 of the basic step angle by controlling the flow of the coil 11 of the excitation coil. However, controlling the current to the excitation coil requires constant current control, which makes the power amplification stage complex and expensive, making it difficult to implement and limiting its application. . However, recent OAR
With the increase in the number of machines and their increasing functionality, the application of step motors, which have the characteristics of low noise and sieving performance, has expanded, and these have become the demands of the times. A drive circuit including a power amplification stage can achieve high resolution, but the degree of resolution has not been selectable in conventional commercially available products. Some motors require high-speed control due to their characteristics, while others require high resolution, and when selecting motors for embedded devices, a general-purpose drive circuit that allows selection of various resolutions and speeds is also desired.

[Objective of the Invention 1] The present invention has been provided in view of the above-mentioned points, and is to realize switching of the excitation method easily and at low cost, and to easily switch the excitation method according to the user's application. The present invention also provides a drive circuit for a step motor with the objective of being able to perform the following steps.

[Disclosure of the Invention 1 (Configuration) The present invention includes a counter that counts input pulses, and parallel output pulses from this counter are input, and data corresponding to a preset excitation coil current value is stored and counted. A ROM that outputs data as well as an excitation coil current signal that switches the excitation method stored in advance according to the input excitation method switching input (No. 5);
D/ which converts the output data from to an analog voltage and outputs it to the PWM constant current circuit as the excitation coil current setting voltage.
The present invention is characterized in that the reference voltage setting circuit is configured with an A converter.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram. Counter 1, which is an up-run counter, receives a series of pulse signals (JP, CCWll) that determine the rotational direction of motor M, and the 4-bit counter 1 output is the address of ROM 2. Given as an address to input AD, ~AD, RO
M2 stores a digital value corresponding to a preset excitation coil current value of the step motor as data, and outputs the data of the digital value. Further, an excitation method switching input signal is input to addresses ADS and AD of the ROM2. The two pairs of PWM constant current circuits 5 and 6 control the excitation coil of the motor M by passing a pulsed constant current at appropriate intervals.

An analog voltage obtained by converting the digital value from the ROM 2 by the D/A converters 3 and 4 is input to the PWM constant current circuits 5 and 6, and the excitation coil of the motor M is controlled with a constant current using this analog voltage. I have to. Note that the counter 1, ROM 2, and D/A converters 3 and 4 constitute a reference voltage setting circuit.

Next, the operation will be explained. ? The pulse input of Tf' is converted into a 4-bit signal by counter 1, and the 4-bit signal is
(No. 4 sets the address of R(') M 2 and outputs the corresponding data. Here, some of the addresses of ROM 2) AD3. As shown in the table below, ROM 2 contains two-phase excitation signal patterns, 1-
Three types of signal patterns are stored for 2-phase excitation (, pattern, and double 1-2 phase excitation, and depending on the combination of [HJ and rLJ of the excitation method switching input), three types of patterns can be selected. The selectable items are shown in Table 1. The ROM2 output has current direction switching signals c and e and output current value setting signals d and f. Current direction switching signals c and e are directly sent to the PWM constant current circuits 5 and 6. and switches the direction of the output current.In addition, the output current value setting signals d and f1
．． After being converted into a corresponding voltage value by the tD/A converters 3 and 4, it is applied to a PWM constant current circuit 5.6 to adjust the magnitude of the output current. In this way, the selection function of 2-phase excitation, 1-2 phase excitation, and double 1-2 phase excitation can be realized very easily by only using some bits of the address of the ROM 2. This allows the motor M to
In a system that requires switching the knob angle, the switching can be done using only logic signals without changing the motor M.

[Effects of the Invention] As described above, the present invention supplies excitation current to each excitation coil of a two-phase step motor having two-phase excitation coils, and excites the excitation coils at appropriate intervals to perform constant current control. In a step motor drive circuit that includes two pairs of PWM constant current circuits and a reference voltage setting circuit that is input to the PWM constant current circuits and generates a voltage for setting an excitation coil current, a counter that counts input pulses and , inputs parallel output pulses from this counter, stores data corresponding to a preset excitation coil current value, and outputs the data, and also outputs the excitation coil stored in advance according to the input am mode switching input signal. The reference voltage is set by a ROM that outputs an exciting coil current signal for switching the method, and a D/A converter that converts the output data from this ROM into an analog voltage and outputs it to the PWM constant current circuit as the exciting coil current setting voltage. Since it is a circuit, R
By just using some bits of the OM address,
Very easily, for example 2 phase excitation, 1-2 phase excitation, double 1
- This has the effect of realizing a two-phase excitation selection function. As a result, in a system that requires switching of the step angle of the motor, it is possible to switch only by the Ronokki δ without changing the motor.

Moreover, by using the signal input to the ROM as an excitation method switching signal and outputting data for switching the excitation method according to that signal, there is no need to add any parts, so the price can be reduced. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the invention. 1 is a counter, 2 (earth ROM, 3.4i/A converter), 5 and 6 are PWM constant current circuits.

Claims (1)

[Claims] (1) Two pairs of PWM constant current circuits that supply excitation current to each excitation coil of a two-phase step motor having two-phase excitation coils, and perform constant current control by exciting the excitation coils at appropriate intervals; In a step motor drive circuit that includes a reference voltage setting circuit that inputs to a PWM constant current circuit and generates a voltage for setting the excitation coil current, a counter that counts input pulses and parallel output pulses from this counter are input. and stores data corresponding to a preset excitation coil current value and outputs the data,
A ROM that outputs an excitation coil current signal that switches the excitation method stored in advance according to the input excitation method switching input signal, and converts the output data from this ROM into an analog voltage and uses it as a PWM constant voltage for setting the excitation coil current. A drive circuit for a step motor, characterized in that the reference voltage setting circuit is constituted by a D/A converter that outputs to a current circuit.