JPS6140948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic timepiece, and more particularly to a drive system for its electromechanical conversion mechanism. An object of the present invention is to reduce the power consumption of such a conversion mechanism and also to achieve high reliability.

Since the so-called quartz wristwatch, which uses a quartz crystal as a time standard oscillator, was put into practical use, it has become widely popular due to its high precision and reliability. During that time, technological innovations in crystal wristwatches have been remarkable, and their power consumption, which originally required 20-plus microwatts, can now be achieved at around 5 microwatts. However, if we look at the breakdown of the current power consumption of 5 μW, it is 1.5 to 2 μW due to the oscillation of the crystal oscillator, frequency division, etc.
W, the electromechanical conversion mechanism is 3 to 3.5 μW, which is quite unbalanced.In other words, the power consumption of the electromechanical conversion mechanism accounts for 60 to 70% of the total power consumption, so we will strive to further reduce power consumption in the future. In order to achieve this goal, reducing the power consumption of this electromechanical conversion mechanism seems to be effective. However, the conversion efficiency of current electromechanical conversion mechanisms is quite high, and it is quite difficult to increase the efficiency further. However, conventional electromechanical conversion mechanisms have been designed to operate satisfactorily even under the worst conditions due to requirements such as load-resistant mechanisms such as calendar mechanisms, environmental resistance such as temperature and magnetism, and resistance to external disturbances such as vibration and shock. For this reason, the conversion mechanism was required to have the ability to withstand a certain load under certain driving conditions, but in reality, the watch body is under such load only for about 4 to 5 hours in a day, when other Most of the 20 hours are without load. In other words, if the watch body was always in an unloaded state, the exchange mechanism would not need to be designed to withstand such a large load, and in that case, power consumption could be reduced considerably, but the watch body would However, since the environment is harsh, it was necessary to use a conversion mechanism that can supply large amounts of power and obtain large outputs in order to guarantee this.

The present invention corrects the above-mentioned irrationality by driving the conversion mechanism with less power when the load is small, and with high power when the load is large, and greatly reduces the power consumed by the conversion mechanism. It is intended to reduce Furthermore, such a drive system is constructed using reliable all-electronic means without including mechanical contacts, and a stable drive that can cope with variations due to the type of conversion mechanism and mass production has been realized.

The present invention will be explained below. First, a pulse motor and its operation will be explained as an example of an electromechanical conversion mechanism used in an electronic wristwatch, and the concept of the present invention will be explained based on this pulse motor. Then, examples will be explained in detail. do.

Figure 1 shows an example of a pulse motor for an electronic wristwatch. In the figure, 1 is a permanent magnet rotor magnetized to two poles, and stators 2 and 3 are arranged facing each other with rotor 1 in between. However, these stators 2 and 3 are each connected to a yoke 5 around which a coil 4 is wound to form a set of stators. The stators 2 and 3 have circular arc portions 2a and 3a eccentric to the center of the rotor 1 so that the rotor 1 can rotate in a fixed direction, and the positions of the magnetic poles (N and S) when the rotor 1 is at rest are adjusted. The stators 2 and 3 are shifted to one side. This type of pulse motor has been in practical use for some time and was driven by a circuit block as shown in FIG. A crystal oscillator 10 is driven by an oscillation circuit 11, its frequency is divided by a frequency divider 12, and a waveform shaper 13 generates two pulses having an appropriate time width and a 180° phase difference at an appropriate time interval. is formed.

As an example, let's consider a pulse of 7.8 msec every 2" and explain this below.
Driver 1 consisting of CMOS inverter
4 and 15, and the output is sent to terminal 4 of coil 4.
a, 4b. FIG. 3 is a detailed diagram of this driver section. When a signal 18 is applied to the input terminal 16 of one inverter 14, a current flows as indicated by an arrow 19, and conversely, a current flows to the input terminal 16 of one inverter 14.
When a similar signal is applied to the input terminal 17 of 5, a current flows in a route symmetrical to arrow 19. That is, by alternately applying signals to the input terminals 16 and 17 of both inverters, the current flowing through the coil 4 can be alternately reversed. Specifically, the current flowing through the coil 4 can be reversed alternately at 7.8 msec every second. can be passed to. With such a drive circuit, N and S poles are alternately generated in the stators 2 and 3 of the pulse motor shown in Figure 1, and the rotor 1 can be rotated 180 degrees by repulsion and attraction from the magnetic poles of the rotor 1. . The rotation of the rotor 1 is transmitted to the fourth wheel 7 via the intermediate wheel 6, and further to the third wheel 8, 2.
The signal is transmitted to the number wheel 9, and further to a cylinder pinion, hour wheel, and calendar mechanism (not shown), and operates an indicating mechanism consisting of an hour hand, a minute hand, a second hand, a calendar, etc.

The pulse motor shown in FIG. 1 operates in principle as explained above, and has been used as a conversion mechanism for electronic wristwatches.

In the drive circuit shown in FIG. 3, when a high level signal is applied to the terminal 17 and a signal 18 is applied to the terminal 16, and a current is caused to flow as shown by an arrow 19, a voltage drop based on the drive current occurs in the MOS transistor 15 due to the channel impedance. A signal waveform corresponding to this current can be detected at the generating terminal 4b. The current waveform is as shown in FIG. 4, for example. Fourth
In the figure, section A is a drive section, in this case 7.8 msec, and the current flowing in this section A is the current consumed by motor drive. The reason why the current waveform in section A has a complicated shape as shown in the figure is that in addition to the current generated based on the voltage applied by the drive circuit, there is also an induced current in the coil due to the rotation of the driven rotor. This is because they are superimposed. Section B is the section after the drive pulse is applied, and the rotor rotates due to inertia and vibrates until it stops at a stable position.At this time, in this section, the P-channel MOS transistors of the drive inverters 14 and 15 in FIG. Since it is turned on, an induced current flows to the coil 4 in response to the movement of the rotor in a loop between the coil 4 and this transistor. This is why the waveform in section B in FIG. 4 is pulsating. Therefore, the shapes of the drive current waveform and the induced current waveform after driving can substantially correspond to the rotational position of the rotor.

Now, waveform 20 and waveform 20' in FIG. 4 are a series of waveforms, and this is when the load on the rotor is very small. Waveform 22 and waveform 22' are also a series of waveforms, and in this case, the load on the rotor is large and the rotor is close to its operating limit, while waveform 21 and waveform 21' represent a load that is approximately 1/2 of the maximum allowable load. This is the case when it is multiplied. If you carefully observe the current waveform when the load is changed in this way, you will see that the waveform extends to the right as the load increases.
This is because the rotation of the rotor slows down as the load increases, and it has been experimentally confirmed that the rotor vibration frequency and amplitude become low until it stops at a stable position. Considering this phenomenon in reverse, it can be understood that if the load on the rotor is always in a no-load state, the rotor can be driven with a short pulse width of 7.8 msec. In fact, even if the pulse width is shortened, the motor still operates and the output torque decreases. This situation is shown in FIG. FIG. 5 shows the output torque characteristic T and the power consumption characteristic I when the drive pulse width is changed.
The aforementioned driving pulse width of 7.8 msec corresponds to P ₂ in this figure. That is, the output torque is T ₂ with a pulse width of P ₂ and the power consumption is I ₂ . As mentioned above, this output torque T ₂ is set so as to be able to sufficiently withstand the load encountered by the watch body. However, if the load on the rotor is small or negligible, the output torque can be small and the drive pulse width can be shortened.
Therefore, power consumption can also be reduced. For example, if it is driven with a pulse width of P ₁ , the output torque will be T ₁ and the power consumption will be I ₁ . The present invention focuses on this point, and by detecting the load on the rotor, drives with a narrow pulse width when there is no load or a small load, and drives with a wide pulse width when a large load is applied. It is designed to rationally reduce power consumption. As mentioned before, the overwhelming majority of people are in a no-load state, so the effect of reducing power consumption is very large. For example, as shown in Figure 5, when driving with a pulse width of P ₁ during no load (20 hours) and with a pulse width of P ₂ during load (4 hours), and assuming that I ₁ /I ₂ = 1/2. , the average power consumption is: I=I ₁ ×20+I ₂ ×4/24=14/24I ₂ ≒0.
58I ₂ , which requires less than 60% of the power compared to the conventional method, which was driven with a constant pulse width of P ₂ , resulting in a significant reduction in power consumption.

By the way, although it was briefly mentioned above that ``the load is detected...'', it goes without saying that this method of detecting the load is a major point of the present invention. Next, a method for detecting this load will be described. Looking at the current waveform flowing through the coil in FIG. 4, it can be seen that the current waveform changes as the load increases. That is, in drive section A, the positions of maximum and minimum shift to the right as the load increases. The magnitude of the load can be determined by focusing on this point, but the amount of change in this waveform is extremely small, making it difficult to absorb variations in mass production and requiring extremely delicate control.

Therefore, the present invention focused on section B after application of the drive pulse. Also in this section B, as the load increases, for example, the point where the minimum value is first shifted to the right. Moreover, compared to the amount of change in the waveform in section A,
A change several times larger can be obtained. Therefore, it is easier to detect the magnitude of the load based on the induced current waveform in this section B than in the above-mentioned section A, and the reliability is also higher. This phenomenon also occurs when the driving pulse width is shortened, and the situation is shown in FIG. The drive shown in Fig. 6 has a narrow drive pulse width compared to Fig. 4, so it can withstand only a small load, but the drive current waveform 23 at no load and the induced current waveform 23' after driving are similar. Drive current waveform 2 at limit load
4. Similarly, the relationship with the induced current waveform 24' after driving is the same as that shown in FIG. The load is detected by the method described above, but the configuration of the present invention normally drives the motor with a narrow drive pulse assuming no load, and always detects the size of the load from the induced current waveform after driving.
When the load is small, driving is continued with the initial narrow driving pulse width. When the load increases and the limit of driving with a narrow driving pulse width is approached, or when the load suddenly becomes excessive and the motor does not operate, the motor continues to be corrected with a wide pulse width, and at the next drive It drives with a wide pulse width, detects the state of the load at that time, and continues driving with a wider pulse width if the load is too heavy to drive with a narrow pulse width.
If the load is small and it is determined that driving with a narrow pulse width is sufficient, the device is configured to return to driving with a narrow pulse width from the next drive.
This will be explained in more detail with reference to FIG.

FIG. 7 is a block diagram showing the configuration of the present invention, where 25 is a time standard oscillator, 26 is a circuit including an oscillation circuit, a frequency dividing circuit, etc., 27 is a pulse motor drive circuit, and 28 is a pulse motor. The configuration is the same as a conventional electronic wristwatch. 29 is a load detection circuit that detects the load based on the induced current waveform after application of a drive pulse as explained in FIGS. 4 and 6. 30
A control circuit is a circuit that controls the drive of the pulse motor 28 according to the state of the load detected by the load detection circuit 29, and normally controls to supply a narrow drive pulse when there is no load and a wide drive pulse when there is a load. This control system will be explained with reference to FIG. 8th
The figure shows the state of the driving pulses, and the states supplied as described above in the section of the pulse motor are shown as pulses 31 and 32. pulse 3
1 and 32 are narrow pulse widths in the no-load state. After applying the pulses 31 and 32, the detection circuit of FIG. 7 detects a load condition, which is either no load or a small load condition. That is, since the load detection after pulse 31 was determined to be no load, the next pulse 32 has a narrow pulse width, and since the load detection after pulse 32 was also determined to be no load, the next pulse 33 also has a narrow pulse width. In load detection after pulse 33, it was determined that the vehicle was in a loaded state. In this case, several tens of milliseconds after the pulse 33, a second drive pulse 34 with a wide pulse width is applied with the same polarity as the pulse 33 (that is, the same current direction). Therefore, the next driving pulse 35 is driven with a wide pulse width. Then, the magnitude of the load is detected based on the induced current waveform after applying this pulse 35, and it is determined whether driving with a narrow pulse width is sufficient.
If not, driving continues with a wider pulse width. When the load is determined to be small by the load detection after pulse 36, the next driving pulse 37 is applied.
returns to the initial narrow pulse width. In addition, pulse 3
To explain the relationship between pulse 33 and pulse 34, pulse 33
When a large load is detected by driving the
sec later, a pulse 34 with a wide pulse width is applied.This means that the load is determined to be large by load detection after the pulse 33, but it is difficult to determine whether the rotor has operated at this time, as shown in Figure 6. The induced current waveform shifts to the right and attenuates as the load increases. When the rotor does not operate, no induced current is produced, but it is difficult to distinguish this from the situation in which the rotor operates smoothly when the load is close to its limit. If the load increases gradually, even if the load is determined to be large, the rotor will still be operating at the pulse 33 at that time, and if the load suddenly becomes too large to be driven by a narrow pulse width, the rotor will not operate at the pulse 33. It doesn't work. It is difficult to distinguish between the two. Therefore, it is easy to set the load detection after pulse application so that there is some margin. In this configuration, pulse 34 is applied. When the rotor operates with pulse 33,
Since the pulse 34 is a pulse in the same direction as the pulse 33, this pulse 34 is a pulse with an opposite phase, and the rotor does not rotate. Further, when the rotor is not operated by pulse 33, it is driven by pulse 34. At this time, the rotor is driven with a delay of several tens of milliseconds, but this is not visible to the eye as an operation of the second hand, and there is no need to worry about unsightliness caused by this. Next, in this configuration, the load is detected even when driving with a wide pulse width, but this is to reduce the power consumption as much as possible, and also because the load applied to the watch does not always have the same characteristics. This is because it can efficiently deal with various loads that depend on the carrying conditions. That is, the largest load applied to the motor is the load for operating the calendar mechanism, which continues for 3 to 4 hours, and the magnitude of the load also tends to increase gradually. In addition, when the watch is exposed to a magnetic field, placed at low temperatures, or subjected to large disturbances, it also places a load on the motor, but the magnitude of this load varies depending on individual carrying conditions. , duration, etc., vary significantly. Therefore, it is preferable to constantly detect the load, and the structure is such that the size of the load is detected not only while driving with narrow drive pulses, but also while driving with wide drive pulses, and immediately returns to narrow pulses when the load becomes small. It is most effective to do so.

The configuration of the present invention has been described above. Next, specific embodiments of the present invention will be described. FIG. 9 is an example of a load detection circuit and a drive pulse control circuit of a timepiece according to the present invention. In Figure 9, 25 is an oscillation circuit, 26
is a frequency dividing circuit, 28 is a motor, 27 is a drive circuit, 29 is a motor load state detection circuit,
Reference numeral 30 denotes a control circuit, each corresponding to the one shown in FIG. Hereinafter, the circuit elements will be explained one by one. 39 of
The NAND GATE output has a clock to create narrow pulses when driving the motor under no-load conditions.
For example, a clock pulse is generated that is delayed by 5 msec with respect to the falling edge of a 1 second signal. At this time, the delay flip-flop 42 receives the input 1 second signal for 5 msec.
The output is delayed, and a narrow pulse with a width of 5 msec is generated at the output of the gate 46. The flip-flop 44 is a delay flip-flop which receives a 128 Hz clock as input, and its output is delayed by 7.8 msec with respect to the input 1 second signal. Therefore, a pulse with a width of 7.8 msec is obtained at the output of the gate 47, and this is used as a wide drive pulse for driving when a load is applied. The gates 40 and 50 are clocks for generating pulses for determining the no-load state and the loaded state for the time until the minimum portion of the current waveform generated by rotor operation appears after the application of the drive pulse. The gate 40 is for determining when driving with a narrow driving pulse, and the gate 50 is used for determining when driving with a wide driving pulse. Then, by the same operation as 42 and 44, 43 and 48,
And the determination reference pulses are obtained at the outputs of 51 and 52.

10 corresponds to the output narrow pulse of the gate 46, and 59 corresponds to the judgment reference pulse of the gate 48 output. The gate 41 is a correction pulse generation circuit, and the pulse width is a wide pulse of 7.8 msec, and the generation position is in the gate 46 area with respect to the 47 pulses.
For example, there is a delay of 30msec. An example is shown in FIG. 1066. The input terminal 57 of the gate 41 is a correction signal which will be described later, and only when the correction signal becomes HIGH, a correction pulse is generated at the output of the gate 41 and supplied to the subsequent stage. The input signals to the gates 39, 40, 41, and 50 are signals for obtaining the above-mentioned pulses, and are appropriately combined with the outputs of the counter 26. Gate 89,4
9 is the inverter 14, 15 for driving the above pulse.
This is a circuit that separates the signals and outputs them alternately every second. Flip-flop 90 typically has its output Q
is LOW and closes gate 47, but when a correction pulse is issued to the output terminal of gate 41, it is set and its output Q becomes HIGH, and gate 47 is closed.
7 is opened to output a wide drive pulse to the subsequent stage.

Block 29 in FIG. 9 is a circuit for detecting the motor load from the operating state of the motor after application of a drive pulse, and gates 91 and 92 are gates for determining the load at the time of a narrow pulse and at the time of a wide drive pulse, respectively. Hereinafter, first, load detection during narrow pulses will be explained. Reference numerals 53 and 54 are transmission gates that alternately select the outputs of the drive inverters 14 and 15 in accordance with the drive signal.

The outputs of 53 and 54 are combined and input to a differential amplifier 55 via a capacitor. Of the output signals 53 and 54, waveforms in a no-load state and a waveform in a loaded state are shown in FIGS. 60 and 61, respectively. The differentiating circuit operates as a peak detector in this case, and the signal obtained by passing the differentiating circuit output through an inverter becomes a rectangular wave that is inverted at each peak, so that a signal of 62 for 60 and 64 for 61 is obtained. It will be done.
In the signals 62 and 64, the circuit gate 56 detects the falling position after application of the drive pulse, and output detection signals 63 and 65 are obtained. A state in which this falling position is included in the determination reference pulse 59 is determined to be a no-load state, and a state in which this falling position is not included in the pulse 59 is determined to be a loaded state. It is formed by NAND gates 116 and 117. The output 57 of the flip-flop is set HIGH by the 1 second signal input to the gate 115, and when the detection signal 63 is input through the gate 91, the output 57 is reset to LOW. However, since the detection signal 65 cannot pass through the gate 91 due to the output 59 of the gate 48, the output 57 is
It will stay HIGH. The detection signal 65 is clearly determined to be in a loaded state, and the signal 57 becomes HIGH. As a result, for the case of waveform 61, a correction pulse 66 is subsequently applied, which completes the rotation of the rotor. However, as described above, this also includes the case where the rotation of the rotor is completed before 66 is applied. The correction pulse 66 sets the flip-flop 90 and turns on the gate 47.
Then, a wide pulse is supplied as the next driving pulse. After driving with this wide drive pulse, the state of the load is detected in the same way as the load detection with the narrow drive pulse described above. That is, if the first minimum value of the induced current waveform during the wide drive pulse as shown in FIG. 4 occurs within the time set by the gate 52, a no-load state is established.
If it does not occur, the gate 92 determines that it is a loaded state. When the output of the gate 92 is applied (no load state), it is input to the clock terminal of the flip-flop 90, and its output Q becomes LOW, closing the gate 47, and the next driving pulse becomes a narrow pulse. 57 is LOW while wide pulse is supplied
state, and no correction pulse is output. This is because the motor is considered to have sufficient output torque during wide pulse driving.

In this embodiment, as shown in FIG. 9, the load detection circuit 29 includes a detection circuit 110 and a determination circuit 111, and the detection circuit 110 includes transmission gates 53, 54, a differential amplifier circuit 55, and a differential amplifier circuit 55. , and a NAND gate 56. The judgment circuit 111 is a gate 9 for judgment at the time of a narrow drive pulse.
1, and a gate 92 for determination at the time of a wide drive pulse. The control circuit 30 also includes the narrow drive pulse generation circuit 1.
13, a wide drive pulse generation circuit 114, a memory circuit consisting of a flip-flop 90, and a gate circuit 47 for selecting a narrow drive pulse and a wide drive pulse. The narrow drive pulse generation circuit consists of a NAND gate 39, a flip-flop 42, a NAND gate 46, and an inverter 118, and the wide drive pulse generation circuit consists of a flip-flop 44, a NAND gate 47, and an inverter 118.

As the peak detection circuit, various systems can be considered in addition to the 55 differential amplifier circuit. Figure 18 shows
This is a block diagram of a peak detection circuit using a delay circuit. In the figure, 53 and 54 are transmission gates, and 8
0 is a general amplifier replacing 55 in FIG. 9, 81 is a delay circuit, and 82 is a comparator to which the outputs of 80 and 81 are input. An example of the amplifier 80 is shown in FIG. 13 or 14. Since the motor drive detection waveforms 23, 24, etc. mentioned above are signals of several mV to several tens of mV that are substantially generated near the power supply level, the resistor 6
The voltage is divided by 6 and 67 and converted to the input operating level of the amplifier. A waveform shown in FIG. 16 76 appears at the terminal 68. FIG. 14 is an improved circuit of FIG. 13, in which a MOS transistor is inserted in place of the resistor 67, and it has a return circuit that controls the channel impedance of the transistor 69 so that the amplifier input level becomes the operating level. , block 7
0 is a circuit that detects the output level. FIG. 15 shows a simple embodiment of the delay circuit 81, in which 71,
73 is a transmission gate, and 72 and 74 are load capacitors. In this case, the input signal 76 at terminal 68 is delayed as 77 at the output terminal. FIG. 17 schematically represents this waveform. Input signal 76 is transmitted to capacitor 72 by transmission gate 71, and the terminal voltage waveform of 72 becomes 79. Furthermore, a waveform 77 appears at the output terminal 75 by the transmission gate 73. Comparator 82 detects waveforms 76 and 77
When input, a rectangular signal shown at 78 is output. Figure 15 is suitable as a delay circuit, but
In addition, since the input signal frequency is relatively low, a bucket brigade type data transfer element or the like is also suitable.

It has been confirmed that the load detection method of the present invention operates effectively even in the case of magnetic fields or shocks applied to the watch body. FIG. 19 shows a detected current waveform when a DC magnetic field is applied in the direction of the coil of the pulse motor. 83 is a case where the directions of the magnetic field induced in the motor inner core by an external magnetic field and the driving magnetic field are opposite to each other, and 84 is a case where both magnetic fields are in the same direction.
At 83 and 84, waveforms 85 and 86 have zero external magnetic field, and can be considered to be substantially the same waveforms. 87,8
8 is a waveform when the external magnetic field is 40 Gauss. According to the waveform, the operation in the direction 83 becomes more difficult as the external magnetic field becomes stronger, and exhibits the same characteristics as the operation when the load becomes large. Therefore, the timepiece circuit according to the present invention operates effectively even under the influence of external magnetic fields, and it has been experimentally established that the strength against external magnetic fields is no different from that of conventional timepieces. 19th
In the case of FIG. 87, since the minimum position of the waveform appears after the determination reference pulse, a correction signal indicated by 87' is added. From the above explanation, it can be easily inferred that the present invention has an effective effect on impact resistance as well.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described here, and various improvements and modifications can be made. For example, the electromechanical conversion mechanism is not limited to the pulse motor described here. 11th pulse motor
Even the pulse motor shown in the figure can be realized with exactly the same configuration. In the pulse motor shown in FIG. 11, the rotor 100 is made of a permanent magnet, and the stator 1
01 is of a one-piece type with no gap, unlike the one shown in FIG. 1, and is provided with notches 102 and 103 for determining the static position of the rotor. 104 is a drive coil. This kind of pulse motor is
Since the stator 101 is connected, the induced current after driving is as shown in FIG. 4 and 6.
It is slightly different from the figure. However, waveform 1 at no load
It will be understood that the relationships between the waveforms 05 and 105' and the load waveforms 106 and 106' are basically the same and can be realized using the same method.

As described above, according to the configuration of the present invention, the load state is determined by detecting the induced current generated in the coil after the drive current is applied, and depending on the determination state, the next drive pulse output is a narrow drive pulse or a wide drive pulse. A memory circuit is provided to remember whether the pulse is a pulse, and a gate circuit selects a narrow drive pulse or a wide drive pulse according to the output of the memory circuit, so the pulse motor can always be driven with the optimal drive pulse width, ensuring reliable operation. This provides both smooth operation and low power consumption.

[Brief explanation of the drawing]

FIG. 1 shows an example of a pulse motor for an electronic wristwatch according to the present invention. 2 and 3 show conventional circuit configurations, and FIG. 4 shows a current waveform of a pulse motor drive coil in a conventional timepiece. FIG. 5 is a diagram showing the relationship between output torque and power consumption with respect to the drive pulse width of the pulse motor. FIG. 6 shows the coil current waveform when the motor is driven with a pulse width narrower than the conventional drive pulse. FIG. 7 shows a circuit block of a timepiece according to the invention. FIG. 8 is an example of a time chart of motor drive pulses by the circuit according to the present invention. FIG. 9 shows a specific example of the block circuit shown in FIG. FIG. 10 is an example of a time chart of the load detection section in FIG. 9. FIG. 11 shows an example of a pulse motor for an electronic wristwatch according to the present invention. 1st
FIG. 2 shows a coil current waveform during narrow pulse driving in the pulse motor of FIG. 11. 13 to 18 show other examples of the load detection section in FIG. 9. FIG. 19 shows changes in the coil current waveform when a DC magnetic field is applied to the electronic wristwatch according to the present invention. 25... Oscillation circuit, 26... Frequency dividing circuit, 27...
... Drive circuit, 28 ... Motor, 29 ... Motor load detection judgment circuit, 30 ... Control circuit, 31 to 33
... Narrow pulse drive signal, 34 ... Correction signal, 35
...Wide pulse drive signal, 59...Load judgment reference pulse, 60...No load detection signal, 61...Load detection signal.

Claims (1)

[Claims] 1. An oscillation circuit 25, a frequency division circuit 26 that divides the frequency of the output of the oscillation circuit, a drive circuit 27 that operates based on the output signal of the frequency division circuit, and a coil, a permanent magnet rotor, and a stator. The electronic timepiece includes a load detection circuit 29 that is connected to the coil and detects a rotor load from an induced current generated in the coil after a drive current is applied, and a pulse motor 28 that is driven by the frequency dividing circuit 26. and a control circuit 30 that is connected between the drive circuit 27 and the load detection circuit 27 and selectively outputs narrow drive pulses and wide drive pulses to the drive circuit according to the output of the load detection circuit.
is composed of a detection circuit 110 that outputs a load detection signal according to the induced current generated in the coil, and a determination circuit 111 that is connected to the detection circuit 110 and determines the load state from the load detection signal, and the control circuit Numeral 30 includes a narrow drive pulse generation circuit 113 for forming the narrow drive pulse, a wide drive pulse generation circuit 114 for forming the wide drive pulse, and a drive pulse to be outputted next depending on the output of the determination circuit 111. The present invention is characterized in that it is comprised of a memory circuit 90 that stores whether the drive pulse is a drive pulse or the narrow drive pulse, and a gate circuit 47 that selects the narrow drive pulse or the wide drive pulse according to the output of the memory circuit 90. electronic clock.