JPH0213559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single step drive with closed loop control of a stepping motor.

Conventionally, open-loop control has been used to drive a stepping motor in a single step. A method of restarting energization to the energized phases; (2) changing the proportion of current in each phase when energization is always applied to two or more phase coils, such as in 2-2 phase excitation drive of a stepping motor; There is a microstep drive system in which one step of the motor is further divided into smaller steps by dividing the motor into smaller steps, and the motor is controlled with the resolution of the divided steps (microsteps).

Method (1) is a method in which the energization time and energization stop time are determined in advance through experiments, and the sequence of energization time is determined based on this. It is extremely difficult to obtain good step response characteristics due to problems such as increased motor vibration and step-out due to fluctuations, and the braking force during deceleration is mostly due to the frictional load of the motor. Therefore, it has the disadvantage that it is weak and the deceleration time is long.

In addition, method (2) is open-loop control, but since one step of the stepping motor is subdivided and the motor is controlled with this resolution, vibrations caused by motor load fluctuations and power supply voltage fluctuations can be controlled with step resolution. A good step response is obtained since it is reduced by the same rate as the increase. However, this method requires as many circuits as the number of motor phases to vary the current flowing through the coils of each phase of the motor by the step resolution of the motor.The circuit is complex, and generates a lot of heat due to current control, making it very costly. It has disadvantages such as being expensive.

An object of the present invention is to eliminate the above-mentioned disadvantages and to enable reliable single-step braking even in a stepping motor with a so-called low detection angle resolution, which is equipped with a position detector having an angular resolution similar to one step angle of a stepping motor. The purpose of the present invention is to provide a stepping motor drive method that eliminates motor braking failure in, for example, daisy wheel printers and serial dot printers, and enables printing at a predetermined position at high speed and accurately without positional deviation. do.

Examples of the present invention will be described in detail below.

FIG. 1 shows the phase relationship between the position detector of the stepping motor and the rotor and stator of the stepping motor in the stepping motor drive system of the present invention, where 4 is the rotor of a 4-phase PM type stepping motor, and 5 is the rotor of the stepping motor. indicates the stator, 6 indicates the A and B phases of the stator, 7 indicates the C and D phases of the stator, and 8 to 10 indicate the detent positions of the stepping motor.

The optical position detector 3 is adjusted by a phase adjustment device 11 so as to detect the slit 2 of the timing disk 1 at the midpoint between the detent positions and generate a detection pulse.

FIG. 2 shows a driving circuit of the stepping motor driving method of the present invention, where 12 is a stepping motor;
15 is a stepping motor coil power switching circuit, and 16 is an Exclusive OR circuit (hereinafter referred to as EOR).
17 is a stepper motor phase drive pulse generation circuit, 18 is a NOR circuit, 21 is an up counter, 22 is a timing pulse waveform shaping circuit, and 23 is an acceleration data generator for obtaining deceleration time data from acceleration time data. a selection circuit for selecting a memory address from 24, a deceleration data memory;
5 is a down counter with parallel input, 26 is a timing pulse delay circuit for reading parallel input to the down counter 25, 28 is a clock pulse generator, 29 is a stepper motor start pulse input terminal, 30 is a stepping motor The motor rotation direction signal input terminal 31 is an inverter circuit. An energization switching circuit that switches to reverse phase energization during deceleration is constituted by an EOR circuit 16 and each phase drive pulse generation circuit 17.

When a “HIGH” or “LOW” status signal is input to the rotation direction input terminal 30,
By inputting one pulse to the start pulse input terminal 29, each phase drive pulse generation circuit 17
A driving pulse for each phase coil is output from the detent position for state transition to the adjacent detent position according to the rotation direction. After the start pulse is input to the EOR circuit 16, since the output Q of the R-S flip-flop 19 is "HIGH", the EOR circuit 16 outputs an output specifying the rotation direction input from the rotation direction signal input terminal 30. Coil power switching circuit 1
5 starts energizing the coil of the motor 12 for movement to the adjacent detent position. A timing disk 1 directly connected to the motor shaft and a position detector 3 that detects a slit divided at an angle similar to the step angle of the motor on this disk output a timing pulse at the midpoint between the motor detent positions. It has been adjusted as follows. When the start pulse is input, the up counter 21 is reset. Also at this time, R-S flip-flop 19
The output Q of becomes “HIGH” and the AND circuit 20
The pulse generated by the pulse generator 28 in the OPEN state is input to the clock input terminal of the up counter 21, and the up counter 21 starts counting.

When the motor rotates and a timing pulse is output from the position detector 14, the output Q of the R-S flip-flop 19 becomes "LOW" again and the up counter 21 stops counting. At this time, EOR
The output of the circuit is reversed, and the energization to each phase coil of the motor is switched to reverse phase energization for rotating the motor in the reverse direction. The output of the up counter 21 is input to a selection circuit 23 which selects a memory address in the memory 24 from the acceleration time data. The memory 24 stores data on deceleration time measured in advance according to the acceleration time of the motor, and the selection circuit 23 specifies a memory address where deceleration time data corresponding to the acceleration time data is stored. As a result, deceleration time data is output from the memory 24, and the timing pulse is set in the down counter 25 by the pulse delayed by the delay circuit 26. The down counter 25 counts down the clock generated by the pulse generator 28 by the count clock inputted only when the output Q of the R-S flip-flop 19 is "LOW" through the AND circuit 27. The motor is energized in reverse phase and rapidly decelerated. When the output of the down counter 25 becomes "0" (when the deceleration time ends), the output Q of the R-S flip-flop 19
becomes "HIGH" again, the EOR circuit 16 is reversed again, and the coils of each phase of the motor are energized again in the same way as before the start of deceleration, and while decelerating, the rotor reaches the next detent position. Fixed in position. By setting the deceleration time relative to the acceleration time so that the speed becomes zero when the rotor reaches the next detent position, the rotor can be stopped without vibration. In addition, regardless of whether the motor rotates clockwise or counterclockwise, a timing pulse is output at the midpoint of the rotor's detent position, eliminating the need for separate detectors for each rotation direction. Benefits such as the ability to share software can be obtained. Furthermore, when the power supply voltage of the motor fluctuates or when the inertial load fluctuates, the time interval from when a timing pulse is output from the time the motor starts driving to when the motor reaches the next detent position fluctuates greatly. However, even in these cases, since the acceleration time interval and the deceleration time interval have an optimal relationship set in advance, single-step driving of the stepping motor can be realized without vibration. Furthermore, it is possible to perform optimal driving at a lower cost than the microstep driving method. As described above, according to the stepping motor drive method of the present invention, even if the stepping motor is equipped with a position detector that has only a negative resolution corresponding to one step angle, the motor can be moved at an intermediate point between the motor detent positions. Since the acceleration time of the brake is detected and braking is performed by immediately energizing the reverse phase according to the optimal deceleration time stored in advance in correspondence with various acceleration time values, highly accurate single-step braking is possible. Therefore, for example, the present invention can be applied to a daisy wheel printer that is equipped with a stepping motor with a low detection angular resolution and prints by rotating the circular disk on which type is provided, and a serial dot printer that prints dots by moving a carriage. This eliminates braking failure of the motor, eliminates printing misalignment, and enables high-speed and accurate printing at predetermined printing positions.

[Brief explanation of drawings]

FIG. 1 shows the phase relationship between the stepping motor position detector and the stepping motor in the stepping motor drive system according to the present invention. FIG. 2 is a circuit example of the stepping motor drive system according to the present invention.

Claims (1)

[Scope of Claims] 1. In a closed loop drive device for a stepping motor that performs deceleration control and drive control by energizing the stepping motor in reverse phase, a position detection pulse is generated at an intermediate point between detent positions of the stepping motor. a position detector having an angular resolution corresponding to one step angle of the stepping motor, and a timer for measuring acceleration time from the start of activation of the stepping motor until the position detection pulse is generated. a storage device which stores in advance optimal deceleration time data for each of the different values of the acceleration time; and a memory address corresponding to the acceleration time data measured by the timer is selected and read from the storage device. a selection device for selecting the optimum deceleration time data; and an energization device for switching the energization of the motor coil to reverse-phase energization and performing reverse-phase energization for a time indicated by the deceleration time data memory after detecting the position detection pulse to perform single-step braking. A stepping motor drive device comprising a switching circuit.