JP2001004763A - Analog electronic clock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an analog electronic clock with less current consumption that does not malfunction even if a disk or a second hand with a large inertial moment is mounted to a second hand shaft. SOLUTION: The analog electronic clock is provided with a bias means 7 that is connected to one end of a drive coil and bypasses a potential level to nearly the middle potential of a power supply voltage, a back electromotive voltage detection circuit 9 that is connected to the other end of the drive coil and detects a back electromotive voltage due to the rotation of a rotor, and a magnetic pole detection means 12 for detecting the magnetic pole position of a rotor being rotated for a stator based on a back electromotive voltage being generated at the back electromotive voltage detection circuit 9. Then, the magnetic pole detection means 12 stops the output of a drive pulse signal based on a detection signal from the back electromotive voltage detection circuit 9, thus obtaining an analog electronic clock with less consumption current that does not malfunction even if a disk or a second hand with a large inertia moment is mounted to a second hand shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an analog electronic timepiece having a step motor.

[0002]

2. Description of the Related Art The battery life of a recent analog electronic timepiece having a stepping motor is significantly longer than in the past. This is due to an increase in the capacity of the battery and a reduction in the current consumption of the circuit, but it largely depends on the reduction in the current consumption by the load compensation function of the step motor. The load compensation function referred to here refers to a method in which the step motor is normally driven with a small driving force, and the step motor is driven with a large driving force only when the load increases.

The above-described load compensation function intermittently opens and closes a loop including a coil of a step motor after the application of a normal driving pulse, detects an induced voltage generated in the coil by free vibration of the rotor at this time, and detects the detected voltage. Generally, the rotation and non-rotation of the rotor are detected by a signal, and when the rotation is detected, the rotor is normally rotated by a correction drive pulse of a large driving force.

A general analog electronic timepiece is shown in FIG.
As shown in FIG. 7, the time is displayed by three hands of an hour hand 61, a minute hand 62, and a second hand 63. As shown in FIG. 7, there is a specially designed timepiece in which a transparent disk 73 is attached instead of the second hand. This disk 73 (hereinafter referred to as a second disk) has a moment of inertia considerably larger than that of a normal second hand, and when used in a timepiece having the load compensation function described above, the rotation of the rotor,
The non-rotation detection is not accurately performed, causing a delay in the clock. The reason for this is that despite the fact that the rotor could not rotate normally, the second disk 73 having a large moment of inertia caused a large rebound, and an induced voltage similar to that at the time of normal rotation was generated. This is not limited to the second disk 73, and the same result is obtained with the second hand having a large moment of inertia. Therefore, the load compensation function described above cannot be applied to the timepiece having the second disk 73, and therefore the second disk 7
The power consumption of a watch with a 3 is large and the battery life is very short.

The present applicant provides a timepiece having a second hand or a second disk having a large moment of inertia, provided with a magnetic pole position detecting means for a rotor, and stopping the output of a driving pulse based on a detection signal from the detection of the magnetic pole position detecting means. It has been found that the current consumption can be greatly reduced by using this method. Examples of documents that disclose technologies related to this technology include WO96 / 18237 and WO97 / 3 filed by the present applicant.
No. 8487 can be cited.

However, the techniques disclosed in the above-mentioned WO 96/18237 and WO 97/38487 are all related to a high-speed driving technique for a rotor of a step motor, and are techniques for driving a second hand or a second disk having a large moment of inertia. It is not about.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, to operate normally even when a second hand or a second disk having a large moment of inertia is attached, and to greatly reduce the current consumption. Is to provide.

[0008]

An analog electronic timepiece according to the present invention comprises, as a first aspect, a step comprising a rotor having a stator, a permanent magnet having at least two poles, and a drive coil magnetically coupled to the stator. An analog electronic device comprising: a motor; a driving pulse generating means for outputting a pulse signal for driving the stepping motor; and a driving circuit for supplying a driving current to the driving coil based on a signal from the driving pulse generating means. In a timepiece, a bias means connected to one end of the drive coil for biasing a potential level to a substantially intermediate potential of a power supply voltage, and a back electromotive voltage connected to the other end of the drive coil and caused by rotation of the rotor A back electromotive force detection circuit for detecting the back electromotive force, and a circuit for the stator based on the back electromotive force generated in the back electromotive force detection circuit. Magnetic pole position detecting means for detecting the magnetic pole position of the rotor inside, wherein the magnetic pole position detecting means detects the detection signal from the back electromotive voltage detection circuit detected during the output period of the first drive pulse signal. Stopping the output of the first drive pulse signal based on the first drive pulse signal and outputting a second drive pulse signal having a phase opposite to that of the first drive pulse signal after a sufficient stop period of the first drive pulse signal. Detecting means for stopping the output of the second drive pulse signal based on the detection signal from the back electromotive voltage detection circuit detected during the output period of the second drive pulse signal; After a sufficient stop period, the first driving pulse signal having the opposite phase to the second driving pulse signal is outputted.

According to a second aspect of the present invention, in the first aspect, the driving pulse generating means outputs a driving pulse signal composed of an intermittent pulse group having a plurality of idle periods, and the magnetic pole position detecting means comprises: And stopping the drive pulse signal based on a comparison result between the detection signal from the voltage detection circuit detected during the plurality of pause periods and the intermediate potential.

According to a third aspect of the present invention, in the first aspect, the magnetic pole position detecting means determines in advance if the detection signal cannot be detected from the back electromotive voltage detection circuit during the output period of the pulse signal. The output of the drive pulse signal is stopped after a predetermined period of time.

According to a fourth aspect of the present invention, in the first aspect, the sufficient stop period is 0.5 seconds or 1 second including the driving pulse signal from the driving pulse generating means.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a drive system showing an example of the embodiment of the present invention, FIG. 2 is a detailed diagram of a drive circuit, a step motor, and a back electromotive voltage detection circuit showing an example of the embodiment of the present invention, and FIG. Waveform diagram showing the operation of the drive system of
FIG. 4 is an enlarged waveform diagram showing the operation of the drive system of FIG. 1, and FIG. 5 is an enlarged waveform diagram showing the operation of the drive system of FIG.

In FIG. 1, reference numeral 1 denotes an oscillation circuit, and 2 denotes a frequency dividing circuit. By combining outputs from various output stages of the frequency dividing circuit 2, a signal necessary for clock driving is created. Reference numeral 3 denotes a waveform shaping circuit which outputs a signal OE as shown in FIG. 3, which is a basis of a drive pulse signal for driving the step motor 6. Although the number of divided pulses of the signal OE in FIG. 3 is four, the number is varied by being controlled by the pulse control circuit 14 described later, and a maximum of eight divided pulses including the pulse indicated by the dotted line are output. . 4 is a drive control circuit that outputs a signal O1in or O2in as a drive pulse signal based on the signal OE, and 5 is a drive circuit that outputs a signal drv1 or a signal drv2 based on the signal O1in and the signal O2in. The motor drivers 5a and 5b shown in FIG. The motor drivers 5a and 5b buffer input signals of O1in and O2in when the signal OE is at "H" level, and make the output high impedance when the signal OE is at "L" level.

Reference numeral 6 denotes a step motor, which comprises a driving coil 6a, a stator 6b, and a rotor 6c shown in FIG.
Each time a current flows through the drive coil 6a in the direction of the solid arrow or in the direction of the dotted arrow, the rotor 6c rotates by 180 degrees,
The hour hand 71, the minute hand 72, and the second disk 73 shown in FIG. 7 are driven via a train wheel (not shown). 7 is a bias means (FIG. 2)
The bias means 7 is provided with switch means 7a, 7
b, bias resistors 7c and 7d having the same resistance value,
It turns off when the signal SE output from the inverter 8 is at "L" level, and turns on when it is at "H" level. Reference numeral 9 denotes a back electromotive voltage detection circuit, which includes a voltage detection circuit 10 connected to the drive circuit 5 shown in FIG. 2 and a hysteresis comparator 11 connected to the voltage detection circuit 10. The voltage detection circuit 10 includes an inverter 10a, a feedback resistor 10b, and an input resistor 10c.
Represents an input resistor 11a, a feedback resistor 11b, an inverter 11
c, 11d. The hysteresis comparator 11 has a delay in the detection timing of whether or not the back electromotive voltage crosses the bias voltage serving as the reference potential, and has an effect of preventing a malfunction due to an external magnetic field or the like.

Reference numeral 12 denotes a magnetic pole position detection circuit which outputs a positive edge detection signal PE when the signal Aout detected by the back electromotive voltage detection circuit 9 crosses the bias voltage Vb in the positive direction (from negative to positive). The detection circuit 12a and the signal Aou
A negative edge detection circuit 12b outputs a negative edge detection signal NE when t crosses the bias voltage Vb in the negative direction (from positive to negative). An OR circuit 13 outputs the positive edge detection signal PE and the negative edge detection signal NE in an OR manner.

A pulse control circuit 14 outputs a signal Ptrg and outputs a signal Ptrg every time the falling signal Pset is supplied from the frequency dividing circuit 2 shown in FIG. Starts outputting the signal OE. Reference numeral 15 denotes a timer circuit which measures a predetermined time after the signal OE becomes "L" and outputs a signal Tup when the positive edge detection signal PE or the negative edge detection signal NE is not received within the predetermined time. Reference numeral 16 denotes a flip-flop circuit that inverts the output signal Q every time the signal Tup is received.

Next, the operation will be described.
An operation in which a second disk having a thickness of 0.1 mm and a specific gravity of 1.4 (moment of inertia of about 2200 milligram square millimeters) is mounted and driven every second will be described.

In FIG. 1, the signal Pse from the frequency divider 2
When t is input to the pulse control circuit 14, the signal Ptrg is output from the pulse control circuit 14 and input to the waveform shaping circuit 3, and the signal OE is output from the waveform shaping circuit 3.
The signal OE becomes “H” during the period tb as shown in FIG. The signal OE indicates that the output signal Q of the flip-flop 16 is “L”.
In the case of the level, it is output to the signal O1in and the output signal Q
Is "H" level, the signal is output as a signal O2in.
In FIG. 3, the output signal Q is at the "L" level immediately after the output of the signal Pset, and in this case, the signal OE becomes the signal O1.
output to in. Therefore, an “H” level drive pulse signal is output from the motor driver 5a, a current flows in the drive coil 6a in the direction of the solid line arrow, and the rotor 6c starts rotating. During this time, the switch means 7a and 7b are both off because the signal SE is at the "L" level.
In FIG. 4, the signal OE is “L” in the period of t2 after the output of the signal OE, and thus the motor driver 5
Since the outputs of a and 5b are in a high impedance state and the switch means 7a and 7b are turned on, the X terminal which is one end of the drive coil 6a is divided into a bias voltage Vb which is a half of the power supply voltage. Is done.

Here, during the period t2 in FIG.
A voltage waveform appearing at the Y terminal, which is one end of a, will be described.

When the outputs of the motor drivers 5a and 5b are in a high impedance state, the switch means 7a and 7b are on, and the voltage of the X terminal is at the level of the bias voltage Vb by the bias resistors 7c and 7d. The voltage value of the Y terminal depends on the rotation of the rotor 6c and the motor driver 5a,
5b, there is no influence of the bias voltage V as in the case of the X terminal.
b. However, immediately after the output of the drive pulse signal during the period tb in FIG. 4, the current flowing through the drive coil 6a is cut off to generate an induced voltage as shown in Vr in FIG. 4, and the rotation of the rotor 6c due to the output of the drive pulse signal. As a result, a back electromotive voltage Vg is generated as shown in FIG. A composite waveform of these generated voltages appears at the Y terminal, and the voltage waveform appearing at the Y terminal is amplified by the voltage detection circuit 10 and further delayed by the hysteresis comparator 11 to become the waveform shown by Aout in FIG.

In the period t2 in FIG. 4, the induced voltage Vr is dominant immediately after the signal O1in becomes "L",
When the influence of the induced voltage Vr disappears over time, the back electromotive voltage Vg is observed. During the period t2 when the potential level of the back electromotive voltage Vg is higher than the bias voltage Vb, that is, when the rotor 6c is not rotated by about 180 degrees, the waveform of the signal Aout is necessarily biased in a process where the influence of the induced voltage Vr is eliminated. The potential of the voltage Vb crosses from the negative direction to the positive direction (at the point P1 in FIG. 4).

The timer circuit 15 starts a timer operation when the signal OE becomes "L". Flip-flop circuit 16
Is positive, the positive edge detection circuit 12a is in the operating state during the period when the signal OE is "L". The positive edge detection circuit 12a outputs the positive edge detection signal PE when observing that the waveform of the signal Aout crosses the bias voltage Vb from the negative direction to the positive direction at the point P1 in the period t2 in FIG. Further, the timer circuit 15 outputs the signal PE as O.
When received via the R circuit 13, the timer operation is stopped. On the other hand, the pulse control circuit 14 outputs the signal Ptrg after the lapse of a predetermined time if no signal is received from the timer circuit 15 for a predetermined time (t2). The waveform shaping circuit 3 outputs the signal Pt
When rg is received, the signal OE is output at "H" for the period of tc, and thereafter, the same back electromotive voltage is detected in the period of t3 as in the period of t2. Thereafter, in the periods td and te, the above-mentioned tb and tc
The same operation as described above is performed. In the periods t4 and t5, the above-mentioned t2,
The same operation as at t3 is performed.

In the periods t2, t3, and t4 in FIG. 4, the waveform of the signal Aout crosses the potential of the bias voltage Vb from negative to positive at the points P1, P2, and P3, respectively, so that the signal Ptrg is output. "H" signal is output as signal OE. In a period in which the potential level of the back electromotive voltage Vg is lower than the bias voltage Vb, that is, in a period of t5 in FIG. 4, the rotor 6c is rotated by about 180 degrees, and the signal A
The waveform of out does not cross the potential of the bias voltage Vb from negative to positive. Therefore, during the period of t5, the positive edge detection signal P
E is not output.

The timer circuit 15 outputs a signal Tup when a predetermined time (t5) has elapsed without receiving the positive edge detection signal PE during the time t5. The pulse control circuit 14 receives the signal T
When receiving the up, the signal Ptrg is not output, and as a result, the signal OE is not output from the waveform shaping circuit 3, and the driving of the rotor 6c is stopped. At this time, the signal Q of the flip-flop circuit 16 changes from “L” to “H” by the signal Tup.

Next, after a lapse of a sufficient time from the stop of the rotation of the rotor 6c, one second elapses.
When the falling signal of the set signal is input to the pulse control circuit 14, the signal Ptrg is output from the pulse control circuit 14 to the waveform shaping circuit 3, and the signal OE is output from the waveform shaping circuit 3.
Starts to be output. Since the signal Q of the flip-flop circuit 16 is now “H”, the drive control circuit 4 outputs a drive pulse signal to the signal O2in. The subsequent operation is the same as described above, except that the back electromotive voltage detection circuit 9
In the magnetic pole position detection circuit 12 receiving the output signal Aout, the negative edge detection circuit 12b operates. The negative edge detection circuit 12b is connected to the P in the period t2 in FIG.
At a time point 1, when it is observed that the waveform of the signal Aout crosses the bias voltage Vb from the positive direction to the negative direction, a negative edge detection signal NE is output. The timer circuit 15 outputs the signal N
When E is received via the OR circuit 13, the timer operation is stopped. On the other hand, when no signal is received from the timer circuit 15 for a predetermined time (t2), the pulse control circuit 14 outputs the signal Ptrg after the predetermined time has elapsed. I do. When receiving the signal Ptrg, the waveform shaping circuit 3 outputs the signal OE at “H” during the period tc, and thereafter detects the back electromotive voltage during the period t3 as in the period t2. Thereafter, in the periods td and te, the above-mentioned tb and tc
The same operation as described above is performed. In the periods t4 and t5, the above-mentioned t2,
The same operation as at t3 is performed.

In a period in which the potential level of the back electromotive voltage Vg is higher than the bias voltage Vb, that is, in a period t5 in FIG. 5, the rotor 6c is rotated by about 180 degrees, and the signal Aou
The waveform t does not cross the potential of the bias voltage Vb in the positive to negative direction. Therefore, during the period of t5, the negative edge detection signal NE is not output from the negative edge detection circuit 12b during this period.

The timer circuit 15 outputs a signal Tup when a predetermined time (t5) has elapsed without receiving the negative edge detection signal NE during the time t5. The pulse control circuit 14 receives the signal T
When receiving the up, the signal Ptrg is not output, and as a result, the signal OE is not output from the waveform shaping circuit 3, and the driving of the rotor 6c is stopped. Conventionally, the rotor 6c is driven by eight divided drive pulse signals, but in the present invention, the rotor 6c can be driven by four divided drive pulse signals, so that the current consumption is greatly reduced.

In the above description, the case where the second disk having a diameter of 20 mm is driven has been described.
m, the load becomes lighter, and the rotor 6c becomes approximately 18
Since the time required to rotate 0 degrees is short, the number of divided drive pulse signals is less than four. Conversely, if the diameter of the second disk exceeds 20 mm, the load becomes heavy and the rotor 6
Since the time required for c to rotate about 180 degrees becomes longer, the number of divided drive pulse signals becomes five or more. Note that the number of divided drive pulse signals is a maximum of eight, and is set in advance so that the number does not exceed eight even if the load is heavy. Further, the second disk may be driven every 0.5 seconds instead of every second. In this case, the current consumption increases as compared with the case of driving every one second. Therefore, it is necessary to change the specification of the step motor in advance so that the current consumption does not increase so much.

[0029]

As is apparent from the above description, according to the present invention, the optimum driving pulse width is automatically set to the optimum driving pulse width even if a second hand having a large moment of inertia or a second disk having a large moment of inertia is attached. Since the setting is performed, an analog electronic timepiece with low current consumption can be obtained, and some of the effects can be greatly enhanced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a drive system showing an example of an embodiment of the present invention.

FIG. 2 is a detailed diagram of a drive circuit, a step motor, a bias unit, and a back electromotive voltage detection circuit according to an embodiment of the present invention.

FIG. 3 is a waveform chart showing an operation of the drive system of FIG.

FIG. 4 is an enlarged waveform diagram illustrating an operation of the drive system of FIG. 1;

FIG. 5 is an enlarged waveform diagram illustrating an operation of the drive system of FIG. 1;

FIG. 6 is an external plan view of an analog electronic timepiece to which a conventional second hand according to the related art and the present invention is attached.

FIG. 7 is an external plan view of an analog electronic timepiece to which the second disk having a large moment of inertia according to the present invention is attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillation circuit 2 Divider circuit 3 Waveform shaping circuit 4 Drive control circuit 5 Drive circuit 6 Step motor 6a Step motor drive coil 6c Step motor rotor 7 Bias means 9 Back electromotive voltage detection circuit 10 Voltage detection circuit 11 Hysteresis comparator 12 Magnetic pole Position detection circuit 12a Positive edge detection circuit 12b Negative edge detection circuit 14 Pulse control circuit 15 Timer circuit 16 Flip-flop circuit

Claims (4)

[Claims] 1. A step motor comprising a stator, a rotor having at least two poles of permanent magnets, and a drive coil magnetically coupled to the stator, and a drive for outputting a pulse signal for driving the step motor. An analog electronic timepiece having a pulse generator and a drive circuit for supplying a drive current to the drive coil based on a signal from the drive pulse generator, wherein the analog electronic timepiece is connected to one end of the drive coil and changes a potential level to a power supply voltage. A bias means for biasing to a substantially intermediate potential, a back electromotive voltage detection circuit connected to the other end of the drive coil and detecting a back electromotive voltage generated by rotation of the rotor, and a back electromotive voltage detection circuit. Magnetic pole position detecting means for detecting a magnetic pole position of the rotating rotor with respect to the stator based on the generated back electromotive voltage. The pole position detection means stops output of the first drive pulse signal based on the detection signal from the back electromotive voltage detection circuit detected during an output period of the first drive pulse signal, and After a sufficient stop period of the drive pulse signal, a second drive pulse signal having a phase opposite to that of the first drive pulse signal is output, and the magnetic pole position detecting means detects the output during the output period of the second drive pulse signal. Stopping the output of the second drive pulse signal based on the detection signal from the back electromotive voltage detection circuit, and after a sufficient stop period of the second drive pulse signal, An analog electronic timepiece which outputs a drive pulse signal. 2. The driving pulse generating means outputs a driving pulse signal composed of an intermittent pulse group having a plurality of pause periods, and the magnetic pole position detecting means detects the driving pulse signal during the plurality of pause periods. 2. The analog electronic timepiece according to claim 1, wherein the drive pulse signal is stopped based on a comparison result between the detection signal from the voltage detection circuit and the intermediate potential. 3. The method according to claim 2, wherein the magnetic pole position detecting means detects the drive pulse signal after a predetermined time if the counter electromotive voltage detection circuit fails to detect the detection signal during the output period of the pulse signal. The analog electronic timepiece according to claim 1, wherein output is stopped. 4. The analog electronic timepiece according to claim 1, wherein the sufficient stop period is 0.5 seconds or 1 second including the driving pulse signal from the driving pulse generating means.