JP2522912Y2 - Step motor drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a step motor drive circuit that detects the rotation state of a step motor and corrects the rotation.

[Prior art and its problems]

In order to drive the step motor efficiently when the load condition of the step motor changes in various ways, or when the driving capability of the load of the step motor changes due to a change in the ambient temperature, etc., usually, the average load condition and the environment When a drive signal that allows the stepping motor to rotate under the conditions is given, and the stepping motor does not rotate normally by the driving signal, a drive signal (correction pulse) that can supply a greater amount of driving energy is given to correct the rotation. Is being done. By performing such correction, under normal environmental conditions and load conditions, only driving energy necessary for actually rotating the step motor is supplied, so that waste of driving energy can be eliminated. When the load increases or the environmental conditions become severe and the step motor cannot rotate, a correction pulse is given to correct the rotation.

However, in the case where the light load state (average load) and the heavy load state exist, it is necessary to complete the driving of the heavy load except when the driving of the heavy load is completed by one or several rotations of the step motor. When a fixed time is required, there is a problem that the driving energy is wasted in the above-described conventional correction driving. That is, regardless of the load state of the step motor, an average drive signal is applied first, and a non-rotation is detected, and then a drive signal capable of supplying a larger drive energy is applied. In such a case, a drive signal that cannot drive the load is supplied to the pulse motor every time, resulting in waste of drive energy.

[Purpose of the invention]

An object of the present invention is to provide a step motor drive circuit that can drive a step motor having a variable load condition more efficiently.

[Points of the invention]

According to the present invention, when the non-rotation of the step motor is detected, the correction for dividing the frequency is advanced X times per second for every X seconds, the non-rotation of the step motor is corrected in X seconds, and the correction is completed. After that, a second drive signal having a drive energy larger than the first drive signal is supplied to the step motor until a certain time elapses, thereby correcting the non-rotation of the step motor and preventing the next non-rotation from occurring. is there.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a diagram showing a circuit configuration of an electronic wristwatch of an analog display according to one embodiment. In FIG. 1, an oscillator 1 is composed of a crystal oscillator or the like, and generates a signal of, for example, 32.768 KHz and outputs it to the first frequency dividing circuit 2. The first frequency dividing circuit 2 is 32.7
The 68 KHz signal is frequency-divided to generate a 32 Hz signal, which is output to the second frequency dividing circuit 3. The second frequency dividing circuit 3 is composed of a flip-flop or the like. The second frequency dividing circuit 3 divides the 32 Hz signal from the first frequency dividing circuit 2 to generate a 16 Hz signal and outputs the signal to the third frequency dividing circuit 4.
The third frequency dividing circuit 4 further divides the 16 Hz signal to 1H
A signal of z is generated, and a 1 Hz signal is output to the AND gates 5, 6 and the one-shot circuit 21.

The output of the AND gate 5 is input to the first waveform output unit 7,
The output of the AND gate 6 is input to the second waveform output unit 8.
The first waveform output section 7 and the second waveform output section 8 are connected to an AND gate 5.
When a signal of 1 Hz is given through the first and second signals, the second waveform output unit 8 has a wider ON width than the first waveform output unit 7. Create and output a signal.

The waveform shaping unit 9 is a circuit that creates two types of signals having a phase difference of 180 ° from each other based on the signal from the first waveform output unit 7 or the second waveform output unit 8. Drive circuit 10
Is a circuit for controlling the driving of the stepping motor 11 by alternately switching the exciting current supplied to the stator coil 11a based on a signal having a phase difference of 180 ° from the waveform shaping section 9. The stepping motor 11 includes a stator coil 11a, a stator 11b that is alternately excited by the stator coil 11a to have the opposite polarity, and a rotor 11c that is disposed to face the stator 11b and that is made of a permanent magnet that is magnetized to two poles. The rotation of the rotor 11c is performed through the wheel train mechanism 12 through the hour hand, the minute hand,
A hand 13 consisting of a second hand is rotated, and a calendar mechanism 15 for displaying a day of the week and a date is driven via a transmission mechanism 14.

The stator coil 11a of the step motor 11 has
When the stepping motor 11 is driven by supplying the exciting current,
A rotation detection unit 16 for detecting whether the rotor 11c has actually rotated is connected, and for example, detects whether the rotor 11c has normally rotated from the current induced in the stator coil 11a by the rotation of the rotor 11c. . This rotation detector 16
Detects that the step motor 11 is not rotating, it outputs a signal to enable the set terminal of the RS flip-flop 17, and sets the RS flip-flop 17 to the set state.

In this state, a high-level Q output signal is output from the RS flip-flop 17 to the AND gate 18 and the OR gate 19. The signal output to the OR gate 19 is input to one input terminal of the AND gate 6, and the signal is further inverted by the inverter 20 and input to one input terminal of the AND gate 5. The other input terminals of the AND gates 5 and 6 are supplied with a 1 Hz signal from the third frequency dividing circuit 4, respectively. 5 closes and the gate 6 opens, and a 1 Hz signal is input to the second waveform output unit 8. As a result, the second waveform output unit 8 generates a signal having a wider ON width than the signal generated by the first waveform output unit 7 during normal driving, and the step motor 11 is driven by this signal, which is larger than the normal time. Driving energy is supplied.

The other input terminal of the AND gate 18 to which the Q output signal of the RS flip-flop 17 is input is connected to a one-shot circuit.
When the rotation detector 16 detects non-rotation, the AND gate 18 opens and the one-second cycle signal is used as a correction signal as a correction signal. The signal is output to the frequency dividing circuit 3. By receiving the correction signal from the AND gate 18, the second frequency dividing circuit 3 divides the frequency of the signal which is one pulse larger than the original number of pulses. Output to the third frequency dividing circuit 4.

The hex counter 22 is a counter that counts the number of times that the cycle of the second frequency dividing circuit 3 is corrected 32 times. The number of times the correction signal from the AND gate 18 is counted 32 times. Upon completion, a carry signal is output to reset the RS flip-flop 17 and set the RS flip-flop 23 to a set state. The Q output signal of the RS flip-flop 23 is input to the OR gate 19 and the AND gate 24, and the other input terminal of the AND gate 24 receives the one-second cycle signal from the one-shot circuit 21. The output of this AND gate 24 is N
The carry output of the N-ary counter 25 is input to the reset terminal of the RS flip-flop 23.

In this case, the N-ary counter 25 is, for example, about 2 hours from the start to the end of the driving of the calendar mechanism, that is, 2 × 60
X60 = 7200 base. That is, the step motor
When the non-rotation of 11 is detected, the drive cycle is corrected. For example, after the correction for one rotation is completed, the signal from the third frequency dividing circuit 4 is counted by the N-ary counter 25 and During a period until a predetermined time for the counter 25 to count up elapses, a signal having a wider ON width than during normal rotation created by the second waveform output unit 8 is supplied to the step motor 11 as a drive pulse.

Therefore, when the step motor is not rotated due to a change in the load state or the like, since the step motor is driven by a signal with a wide ON width for a certain time (for example, a time until the driving of the calendar mechanism is completed), the load cannot be driven. The drive signal is not repeatedly supplied, and the drive energy is not wasted.

As described above, according to the above-described embodiment, once the load increases once, such as when driving the mechanism for switching the day of the week and the date of the electronic timepiece, the load continues to be heavier than during normal operation until the switching is completed. In a device having such a load characteristic as to be added, when the non-rotation of the step motor 11 is detected, the step motor 11 is driven with a drive energy larger than a predetermined time together with the correction of the rotation, so that Exciting current is not wastefully consumed, and efficient driving can be performed to reduce power consumption.

[Effect of the invention]

According to the present invention, an appropriate drive signal according to the load state can be supplied to a step motor having a light load state and a heavy load state, and more efficient driving can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of an electronic wristwatch according to an embodiment of the present invention. 7: first waveform output unit, 8: second waveform output unit, 9:
Waveform shaping section, 16 rotation detecting section, 17, 23 RS flip-flop, 25 N-ary counter.

Claims (1)

(57) [Scope of request for utility model registration] A frequency dividing means for dividing a reference clock signal to obtain a synchronizing signal in units of one second, and a step motor is rotationally driven in a one-second cycle based on the synchronizing signal obtained by the frequency dividing means. First signal output means for outputting a first drive signal to be driven; and whether the step motor is rotationally driven or non-rotated when the first drive signal is output from the first signal output means. Detecting means for detecting the non-rotation, X (X
Is a positive number) A correcting means for dividing the frequency by 1 / X second by a frequency dividing means for dividing the one-second second by X times, and a predetermined value after the correction by the correcting means is completed. A second drive signal having a drive energy larger than the first drive signal while the correction by the correction unit is being performed and while the time is being measured by the clock unit. And second signal output means for supplying the signal to the step motor based on the signal obtained by the frequency dividing means. The non-rotation of the step motor driven to rotate every second is corrected in X seconds. A step motor drive circuit, characterized in that: