JPS629875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive circuit for driving a step motor for an electronic timepiece in reverse direction.

In recent years, methods have been developed to electronically reverse the motor of an electronic wristwatch without relying on a mechanical mechanism to adjust the time difference or time.

Conventionally, the method of reverse drive that has been devised is mainly to apply a voltage as shown in Figure 1 to the motor and perform reverse rotation while capturing the transient timing of the rotor movement. When applied to a motor block using the integral stator shown in FIG. 3, a current waveform as shown in FIG. 2 is obtained. _tx shown in Fig. 2 indicates that the stator is magnetized by the previously applied pulse, and when a voltage of opposite polarity is applied by the next alternating pulse, the previously applied magnetization is canceled and the stator becomes reversely polarized. This is the time required to magnetically saturate the minimum width part of the stator so that magnetic poles are formed. This time t _x is influenced by manufacturing variations such as the finish of the parts. Due to this difference in t _x , the rotor motion caused by the pulse P ₁ differs from one motor to another, making it impossible to achieve stable reversal with good mass productivity.

The present invention provides a reverse drive method for a step motor for an electronic timepiece using an integral stator, which eliminates the above-mentioned conventional drawbacks.

Next, the principle of reversing the motor will be explained. First, when P ₁ of the drive voltage waveform in Figure 1 is applied to the motor, the rotor 2 changes from the rest position in Figure 4 a to the magnetic poles N and S in the stator 1 as shown in Figure b, causing the rotor 2 to rotate in the forward rotation direction. start. When the magnetic poles N and S of the rotor 2 are near the notch 3 of the stator 1 [Figure 4-c]
Next, when a pulse P ₂ of opposite polarity to P ₁ is applied to the motor, the rotor 2 starts rotating in reverse. Next, when the magnetic poles of the rotor pass the horizontal axis of the stator [No. 4-d
When pulse P3, which has the opposite polarity to pulse _P2 , is applied to the motor as shown in the figure, the rotor ₂ continues to rotate in reverse, and the pulse P3 is applied to the motor.
When P3 is made a sufficiently long pulse, the rotor 2 settles to the position shown in Fig. 4-e, and then when the pulse _P3 is cut off, the rotor 2 is controlled by the magnetic index and settles to the position shown in Fig. 4-f, that is, the rotor 2 settles to the position shown in Fig. 4-f. 2 is
This means that it has been reversed by 180°. FIG. 2 shows the current waveform at this time. As can be seen from the above principle, it is desirable to cut the pulse P ₁ when the rotor 2 approaches the notch 3 of the stator 1, but if the time t _x to saturate the minimum width of the stator 1 changes, the pulse creating a difference in effective pulse length,
The position of the rotor 2 when the pulse _P1 is turned off differs for each motor. In the present invention, this time t
_x is cancelled, and the position of the rotor 2 is kept constant when the pulse _P1 is cut off.

The present invention will be explained below based on examples.

FIG. 5 shows the voltage waveform of the reverse drive signal according to the present invention applied to the motor. FIG. 6 shows the current waveform at that time. First, a demagnetizing control pulse P _E is applied in the same polar direction as the pulse P ₁ . This degaussing control pulse P _E is made small enough to saturate the minimum width portion of the stator 1 and prevent the rotor 2 from starting to move. Therefore, although there is a time t _x in which the demagnetizing control pulse P _E saturates the minimum width portion of the stator, it does not have any effect on the rotor 2 . The stator is magnetized by this demagnetizing control pulse _PE ,
The residual magnetism remains in the stator and continues to saturate the minimum width portion of the stator 1. When the pulse P ₁ having the same polarity as the pulse P _E is applied after the period P _s , the minimum width portion of the stator is saturated, so P ₁ immediately rises as shown in the current waveform in FIG. Unlike the current waveform in FIG. 2, in FIG. 6 there is no t _x in pulse P ₁ , so the difference due to t _x is ignored.

FIG. 7 is a block diagram of the present invention. The oscillation circuit 50 uses a 32768 Hz crystal, and its output enters the frequency dividing circuit 51. The frequency dividing circuit 51 is composed of 15 stages of flip-flops. A synthesis circuit 52 appropriately inputs the flip-flop signals and synthesizes their waveforms. A forward rotation/reverse rotation signal for controlling forward rotation/reverse rotation is inputted to the combining circuit 52 from a forward rotation/reverse rotation control circuit 55, and its output is inputted to the drive circuit 53.
is input. The output of the drive circuit 53 is input to the motor and drives the motor.

FIG. 8 shows a time chart of the frequency dividing circuit 51, a time chart of the synthesizing circuit 52, and a part of the time chart of the drive signal.

The synthesis circuit 52 generates a reverse rotation pulse Pr and a forward rotation pulse.
Pn, and inverted pulses φ ₁ , φ ₂ , and φ ₃ are synthesized, respectively. Each pulse is represented by the following logical formula.

Pr= ₁₀・₁₁・₁₂・₁₃・₁₄・₁₅ +Q ₁₅・Q ₁₄・Q ₁₃・Q ₁₂・Q ₁₁・Q ₁₀・Q ₉・Q ₈・₇ Pn= ₉・₁₀・Q ₁₁・₁₂・₁₃・₁₄・₁₅ φ ₁ = ₆・₅・₄・Q ₇・Q ₈・Q ₉・Q _{10 ・}Q ₁₁・Q ₁₂・Q 13・Q ₁₄・Q ₁₅ φ ₂ = ₄・Q ₅・₆・Q ₇・₈・Pn φ ₃ = ₄・Q ₅・₆・Q ₇・Q ₈・Pn Figure 9 shows the parts of the composite circuit 52 excluding the above explanation, the forward rotation/reverse rotation control circuit 55, and the drive circuit. This is what is shown.

The normal rotation signal and the reverse rotation signal are input to the set S and reset R of the RS flip-flop 60, and the output Q, thereof is input to the first input of AND gates 61 and 62. The second input of the AND gate 61 is connected to the reverse pulse Pr shown by the logical formula, and the second input of the AND gate 62 is connected to the normal pulse Pn. The outputs of the AND gates 61 and 62 are input to the OR gate 63.
The outputs of are connected to driving inverters 70 and 71 via NAND gates 69 and 70. When the reversal signal is set on the RS flip-flop 60,
The output Q=H,=L. Therefore, the output of the AND gate 62 becomes L, and the inverted pulse signal Pr
is input to drive inverters 70 and 71. Next, when the normal rotation signal is input to the reset signal of the RS flip-flop 60, =H, Q =L, and the output of the AND gate 61 becomes L. Forward rotation pulse
Pn is applied to the driving inverters 70 and 71. Next, the inverted pulse φ ₁ is input to the first input of the OR gate 61, and φ ₂ and φ ₃ are input to the first input of the OR gate 61.
4 is input. The output of NOR gate 64 is input to the second input of NOR gate 65. noah gate 6
The first input of 5 is connected to the output of RS flip-flop 60. The output of the NOR gate 65 is input to the second input of the OR gate 66. Its output is input to the flip-flop 67 clock. The output Q is inverted by this clock signal, and the inverted output is applied to the motor coil 72 via the number gates 69, 68 and drive inverters 70, 71.

FIG. 10 and FIG. 8 show details of the forward rotation and reverse rotation drive signals applied between CD and D.

As described above, according to the present invention, by applying a small pulse P _E in the same polarity direction as the pulse P ₁ so that the rotor does not start moving when the rotor is reversed, the time required to saturate the minimum width portion of the stator of the integrated stator can be reduced. It is possible to eliminate the influence of variations, and it is possible to create a motor that stably reverses rotation in mass production. Furthermore, if the rotor is to be reversed at high speed in the future, it will be necessary to ensure stable operation.

[Brief explanation of the drawing]

Figure 1: An example of a conventional drive voltage waveform for reversing the rotor. Figure 2: An example of a conventional drive current waveform for rotating the rotor in reverse. Figure 3: An example of an integral stator used in the present invention. Figure 4: An example of a rotor state diagram when the rotor rotates in reverse. FIG. 5: An example of the drive voltage waveform according to the present invention. FIG. 6: An example of the drive current waveform according to the present invention. Figure 7: Block diagram of the present invention. Figure 8: Time chart of the frequency divider circuit, synthesis circuit, and drive circuit. Fig. 9: Specific configuration example of the embodiment. FIG. 10 is a time chart of forward rotation and reverse rotation drive signals according to the present invention. DESCRIPTION OF SYMBOLS 1... Stator of integrated stator, 2... Rotor, 3... Notch position of stator, 50... Oscillation circuit, 51... Frequency dividing circuit, 52... Synthesizing circuit, 5
3... Drive circuit, 54... Motor, 55... Forward rotation, reverse rotation control circuit, 60... RS flip-flop, 61, 62... AND gate, 63, 66...
...Or Gate, 64, 65...Noah Gate, 6
9, 70...NAND gate, 67...Flip-flop, 70, 71...Inverter, 72...Coil.

Claims (1)

[Scope of Claims] 1. A step motor having a stator and a rotor that are integrally formed through a narrow portion, a drive circuit that supplies predetermined drive pulses to the step motor,
a forward rotation/reverse rotation control circuit for controlling forward rotation and reverse rotation of the step motor; and a forward rotation drive signal and a reverse rotation drive signal selectively outputted to the drive circuit by the output of the forward rotation/reverse rotation control circuit. 1. A step motor drive circuit for an electronic watch, wherein the reverse rotation drive signal includes a demagnetization control signal for removing magnetization in a narrow portion of the stator. 2. The drive circuit for a step motor for an electronic timepiece according to claim 1, wherein the degaussing control signal is output before the step motor is operated in reverse.