JPS62251691A - Electronic timepiece - Google Patents

Abstract

PURPOSE:To securely detect the stop of a timepiece after a source voltage drop by switching and outputting driving pulses for a low voltage from a pulse selecting circuit under control based upon a detection signal from a source voltage detecting circuit when the source voltage drops below a specific voltage, and switching an induced voltage detecting means to a high-sensitivity state. CONSTITUTION:This electronic timepiece has an induced voltage detecting circuit 29 which detects a voltage induced by free vibrations of a stepping motor after normal driving pulses are applied and decides whether or not a rotor 39 rotates or not on the basis of the output signal of the circuit 29, if it is decided that the rotor is not in rotating operation, the rotor 39 is driven with correcting driving pulses. Then, the source voltage detecting circuit 13, a pulse selecting circuit 14, and a detection sensitivity adjusting means 33 which adjusts the detection sensitivity of the circuit 29 are provided and when the source voltage drops below a determined voltage, low voltage driving pulses are switched and outputted from the circuit 14 under the control based upon the detection signal from the circuit 13 and the circuit 29 is switched to a high sensitivity state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic timepiece having a step motor.

[Conventional technology]

In recent electronic watches that have a step motor, the step motor is usually driven with narrow pulse width pulses, and only when these pulses are not being driven, the step motor is driven with wide pulse width pulses. , the current consumed by the step motor is very small.

The means to achieve the above function is to detect the induced voltage generated by the rotor's free vibration after the application of normal drive pulses, and to determine whether the rotor is rotating or not based on this detected voltage. A generally used method is to drive the step motor with a wide correction drive pulse when it is determined.

However, recently, a watch has been commercialized in which a solar cell converts light energy into electrical energy, this electrical energy is stored in a capacitor or a secondary battery, and the capacitor or secondary battery is used as an energy source. The power supply voltage of this watch decreases when it is not exposed to light, so when the power supply voltage drops below a predetermined value, the watch has a function that causes the second hand to advance rapidly every 2 seconds and prompts the user to expose it to light. There is. Furthermore, the width of the low-voltage drive pulse at this time is made wider than the width of the normal drive pulse to ensure reliable drive.

[Problem that the invention seeks to solve]

However, with the photoelectric type clock, if it is not exposed to light, it will eventually stop, but if it is exposed to light again, it will start moving again, so even if the clock is running, if it stops once, there will be an error in the displayed time. Therefore, there was a drawback that it was impossible to tell whether or not it was showing the correct time.

Therefore, even after the voltage drop is detected, the second hand is rapidly advanced every 2 seconds to detect the induced voltage generated by the free vibration of the rotor after the application of the wide low-voltage drive pulse, and based on this detection signal. It is conceivable to notify the stop in some way.

However, since the pulse width is wide after the voltage drop is detected, even if the rotor rotates, an induced voltage due to free vibration will not be generated (((), so even if the rotor rotates, it will be determined that it is not rotating.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art and ensure reliable detection of a clock stop after the power supply voltage drops.

[Means for solving problems]

The electronic timepiece according to the present invention includes a power source voltage detection circuit, a pulse selection circuit that switches and outputs a normal drive pulse and a low voltage drive pulse whose width is 75111 wider than the normal drive pulse, and the detection sensitivity of the induced voltage detection means. and a detection sensitivity adjustment means for adjusting the voltage, and when the power supply voltage falls below a predetermined voltage, the low voltage drive voltage is controlled from the pulse selection circuit by the detection signal from the power supply voltage detection circuit. The present invention is characterized in that the induced voltage detection means is configured to be switched to a high-sensitivity state at the same time that the induced voltage detection means is switched to a high-sensitivity state.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of an electronic timepiece according to the present invention.
2 is an oscillation circuit, and 2 is a frequency dividing circuit, which divides the frequency of the signal from the oscillation circuit 1 until a signal necessary for driving the clock is obtained. 3 is a normal drive pulse generation circuit, which generates 1 pulse as shown in Fig. 2 (al).
It is output every second. 4 is a correction drive pulse generation circuit;
Pulses as shown in Fig. 2 (bl) are generated every second, and the phase is delayed from the normal drive pulse.This correction drive pulse is used only when the rotor 69 cannot be driven by the normal drive pulse. The signal is applied to the circuit 26. 5 is a 2-second drive pulse generating circuit which outputs two consecutive pulses as shown in FIG. 2 (C1) every 2 seconds.

This 2-second drive pulse is applied to the drive circuit 26 in place of the normal drive pulse when the voltage of the power supply 9, which will be described later, falls below a predetermined voltage. Reference numeral 6 denotes a variable-speed 2-second drive pulse generation circuit which outputs continuous pulses with different intervals every 2 seconds as shown in FIG. 2 (dl).

This variable speed 2 second drive pulse is replaced with a 2 second drive pulse when the rotor 69 does not rotate normally during 2 second drive.
It is applied to the drive circuit 26. The normal drive pulse is applied to the OR gate 14d via the AND gate 14a,
The 2 second drive pulse is applied to the OR gate 14d via the AND gate 14b, and the variable speed 2 second drive pulse is applied to the OR gate 14d via the AND gate 14C.

AND gates 14a, 14b, t4c and or gate 1
4d constitutes a selection circuit 14, which is controlled by the output signals of a power supply voltage detection circuit 16 and a flip-flop tube 36 (hereinafter referred to as 5RFF) to be described later, and selects the above three signals. One of the signals passes through the OR gate 14d and the toggle flip-flop knob 1
5 (hereinafter referred to as TFF) and an AND gate 16a,
17a. 7 is a normal coil opening/closing pulse generation circuit, which outputs a series of pulses every second as shown in Figure 2 (tel), and AND gate 18, AND gate 19.20.
and is applied to the drive circuit 26 via the OR gate 21 or 22. 8 is a coil opening/closing pulse generation circuit for 2 seconds, which generates a series of pulses twice at close intervals, every 2 seconds, as shown in Fig. 2(f). .25 and the OR gate 21 or 22 to the drive port wr26.These coil opening/closing pulses are induced by the vibration of the rotor 390 after the rotor 39 is driven by the normal drive pulse and the 2 second drive pulse, respectively. 'This is to make it easier to detect voltage.

16 is a selection circuit, which is composed of AND gates 16a, 16b and OR game = 16C;
a is controlled by the Q output of the TFF 15, and the AND gate 16b is controlled by the Q output of the TFF 15 and the output of a circuit 31 (hereinafter referred to as 5RFF) to be described later. 17 is a selection circuit (anto-game) 17a.

17b and an OR gate 17C, the AND gate 17a is controlled by the Q output of TFF15, and the AND gate 17b is controlled by the Q output of TFF15 and 5RFF31.
is controlled by the output of

26 is a well-known drive circuit (two P-channel MUS)
transistor and two N-channel MUS transistors (
(not shown), and the drive circuit 26 receives the signal that has passed through the selection circuit 16.17 through a buffer 27.27.
and are applied via OR gates 21 and 22. Also, the coil 28 of the step motor is connected to this output terminal O1゜02.
is connected. Reference numeral 29 denotes an induced voltage detection means, in which the induced voltage generated in the coil 28 is determined as a predetermined set voltage vt.
A different signal is output depending on whether it exceeds h or not, and this output signal is applied to the reset terminal R of the 5RFF 31 through the AND gate 60.

In addition, the induced pressure detection means 29 generates a signal due to a drive pulse in addition to the induced voltage due to free imaging, but since the coil opening/closing pulse is applied to the AND gate 60 via the OR gate 32, the drive pulse is not detected. The signal due to the
Only a detection signal based on the induced voltage sampled by the coil opening/closing pulse is applied to the recess/node terminal R of the 5RFF 31. Reference numeral 36 denotes a detection sensitivity adjustment means, which is the essential part of the present invention, and is composed of resistance elements Rr and R2 of about 100KΩ and P-channel MOS transistors Trl and Tr2.
The sources of rt and Tr2 are each connected to the power supply VDfl, and the drains are connected to one end of the coil 28 via resistance elements R+ and Rt, respectively. In addition, normal coil opening/closing pulses are applied to the gates through AND gates 19 and 20, and each time this pulse is applied, transistor T and Trt are turned on, and coil 2 is turned on.
One end of 8 is connected to the 7th port of the power supply via resistive elements Rt and R2, and as a result, the induced voltage detection means 290 input chimbeadance becomes low, so the '-voltage induced in the coil is lower than it actually is. The 2-second coil opening/closing pulse is not applied to the gates of the transistors 'l'rt and 'frt.
As a result, the induced voltage detection means 290 enters a high bias voltage, so that the induced voltage generated in the coil 28 during 2 seconds of driving is y and the transistor 'l' r.
+, the on-resistance of Tr 2 is approximately 2Ω. 5
The output signal of the normal drive pulse generation circuit 6.2 second drive pulse generation circuit 5 is applied to the set terminal S of the RFF 31 via the selection gate 54 constituted by the anti-gates 34a, 54b and the OR gate 34C. The selection gate 64 is controlled by the detection signal of the power supply voltage detection circuit 16 or the inverted detection signal via the inverter 46, and either one is selectively output. The output signal from the output terminal Q of the 5RFF 31 is applied to the AND gates 16b and 17b to control the passage of the correction drive pulse from the selection gate 16.
It is applied to the set terminal S of the FF36. 5RF
The reset terminal R of F36 is connected to the switch SW, and the output signal from the output terminal Q is directly connected to the AND gate 14C.
is applied to the AND gate 1 by valving the inverter 37.
4a114b, 18.26.68.

Next, the operation will be explained.

In this case, the voltage of the power supply 9 is sufficient and is higher than a predetermined voltage, so the power supply voltage detection circuit 16 outputs a HIGH signal (hereinafter referred to as an H signal). Further, the output of the 5RFF 66 is L (described as a JW times signal or less signal). Therefore, and gate 1
4a, 18, 38, and 34a are in the on state, and in this state, the rotor 69 is driven by the normal drive pulse, and after the rotor 69 is driven, rotation or non-rotation of the rotor 39 is detected, and rotation is detected. If detection is performed, the rotor 69 is not driven by the correction pulse, and if non-rotation detection is performed, the rotor 39 is driven by the correction pulse. Note that the detection sensitivity adjustment means 66 is in a low sensitivity state.

To explain in detail, first, the normal drive pulse passes through the AND gate 14a, and then passes through the OR gate 14d to TFF1.
5 and is applied to AND gates 16a and 17a. In this way, the output of TFF15 is switched at the rising edge of the normal drive pulse, the Q output outputs an H signal, and ζ
Assuming that the output is an L signal, AND gate 1
6a is in the on state, the normal drive pulse passes through the AND gate 16a, the OR gate 16C, and the inverter 27.
and is applied to the drive circuit 26 through the OR gate 21. Therefore, current flows through the coil 28 and the rotor 69 is driven. Next, the normal drive coil opening/closing pulse is applied to the AND gates 19 and 19, 20 by activating the AND gate 18, but since the AND gate 19 is in the ON state due to the Q output, which is the 1-1 signal of TFFl5, The normal coil opening/closing pulse passes through the AND gate 19 and the OR gate 2
1 to the drive circuit 26. Further, the normal coil opening/closing pulse that has passed through the AND gate 19 is connected to the P channel M (JS transistor Tr) via the inverter 33a.
applied to the gate of r.

When a normal coil opening/closing pulse is applied to the drive circuit 26, a whisker-shaped induced voltage is generated at one end of the coil 28 due to the free vibration of the rotor 69 after the application of the normal drive pulse ends. However, since the transistor Tr+ of the detection sensitivity adjustment means 66 is turned on at the timing when the whisker-like induced voltage is generated, one end of the coil 28 is connected to the power supply vIllD via the resistive element P1.
The detection sensitivity adjustment means 66 enters a low sensitivity state. Therefore, the whisker-like induced voltage is kept lower than the height that actually occurs. This whisker-like induced voltage is generated when the load is light and the rotor 69 rotates normally.
The induced voltage detection means 29 outputs an H signal beyond th. In this case, the timing for detecting the induced voltage is when the rotor 39 is in its return state after rotating one step, as shown in FIG. Also, if the load is very heavy and the rotor 39 does not rotate normally, the induced voltage will be Vth of the induced voltage detection means 29.
The induced voltage detection means 29 outputs an L signal.

Next, the load is quite heavy (there are cases where the rotor 39 barely rotates, but the timing of detecting the induced voltage in this case is as shown in FIG. In the middle of the process, that is, when the 1-step I drive is complete, the induced voltage will be relatively low. However, if the detection sensitivity adjustment means 66 has high sensitivity, that is, the transistor Tri is in the off state, the induced voltage will be low. This exceeds Vtb of the detection means 29. Therefore, even though the rotor 69 is in the middle of being fed, it is determined that it has rotated normally and no correction pulse is applied to the coil 28.

If the rotor 69 returns to its original position as shown by the dotted line in FIG. 6 due to some kind of load immediately after it is determined to be rotating, this will result in an erroneous detection. Since the clock is driven by normal drive pulses for most of the period, it is desirable to make it as safe as possible when it is driven by normal drive pulses. Therefore, when driving with normal drive pulses, the transistor Trl is turned on at the timing of detecting the induced voltage, that is, the detection sensitivity of the detection sensitivity adjustment means 66 is set to a low sensitivity state, so that the induced voltage is reduced (pressing, The induced voltage generated at the timing during the feeding described above is the V of the induced voltage detection circuit 29.
To ensure safety, do not exceed tb.

Next, the operation when the induced voltage exceeds Vtb of the induced voltage detection means 29 and when it does not will be explained.

As mentioned above, the whisker-like induced voltage occurs when the load is light (rotor 69
When the motor rotates normally, the induced voltage detecting means 29 exceeds 1th, so the induced voltage detecting means 29 outputs an H signal and is applied to the AND gate 60. Since the normal coil opening/closing pulse is applied to the other input terminal of the AND gate 60 at the timing when the induced voltage is generated, the H signal from the induced voltage detection means 29 is applied to the reset terminal R of the 5RFF 31. . Therefore, the Q output of the 5RFF 61, which was held at the H signal by the 7- and 7-G signals, is switched and held at the L signal. Therefore, the AND gate 16b is switched to the OFF state, and the correction pulse from the correction drive pulse generation circuit 4 cannot pass through, so that the rotor 69 is not driven by the correction pulse.

Next, if the load is heavy (unless the rotor 39 rotates one step), the whisker-like induced voltage cannot exceed the voltage of the induced voltage detection means 29, and the H signal is not output from the induced voltage detection means 29. .Therefore, the Q output signal of 5flFF31 remains unchanged from the H signal.Therefore, the AND gate 16
A correction pulse passes through b and is applied to the drive circuit 26 via the OR gate 16C, the inverter 27, and the OR gate 21. Therefore, at one end of the coil 28, a correction pulse FP shown by a dotted line in FIG. Even if there is a rotor 69
can be driven one step.

In the next step, 1 second later, the normal drive pulse causes T
The output of FF15 is switched, and AND gates 17a, 17
b, 20 are turned on, the normal drive pulse passes through the AND gate 17a, is applied to the drive circuit 26 via the OR game) 17C, the inverter 27, and the OR gate 22, and the rotor 39 is driven. Further, the normal coil opening/closing pulse passes through the AND gate 20, valves the OR gate 22, and is applied to the drive circuit 26, as well as the inverter 33b.
is applied to the gate of the P-channel M (JS) transistor Tr2. In addition, 5RFF is generated by the normal drive pulse.
31 is set =), the Q output becomes an H signal, and the AND gate 17b is turned on, preparing to pass the correction pulse. As mentioned above, when the rotor normally rotates due to the drive pulse, the induced voltage detection circuit 29 outputs H.
The signal is output and passes through the AND gate 60 to 5RFF31
Q of 5RFF31 since it is applied to the lyse/node terminal R of
The output is switched to the L signal and the AND gate 17b is switched off, so the correction pulse cannot pass through the AND gate 17b, and the correction pulse does not drive the rotor 69''. If rotation is not possible, an L signal is output from the induced voltage detection circuit 29, and 5R
Since the output of the FF 31 becomes an H signal, the correction pulse passes through the AND gate 17b and is applied to the drive circuit 26 via the OR gate 17C1 inverter 27 and the OR gate 22. Therefore, the rotor 69 is driven by the correction pulse and rotates normally. Thereafter, the same operations as described above are repeated, and the rotor 69 continues to rotate every second.

Next, a case will be described in which the power supply voltage decreases, the voltage of the power supply 9 becomes below a predetermined voltage, and the output of the power supply voltage detection circuit 13 becomes an L signal. In the initial state, the Q output of the 5RFF 36 is an L signal.

In this case, the output of the power supply voltage detection circuit 16 is switched to the L signal, so that the AND gates 14b, 23.34
b is turned on, and the watch enters a fast-forward drive every 2 seconds, that is, a 2-second movement mode, and prompts the user to shine the light because the voltage has become low. Note that the detection sensitivity adjustment means 33 is in a high sensitivity state.

To explain in detail, first, the 2 that passed through the AND gate 14b
The second pulse is applied to the TFF 15 and the AND gates 16a and 17a via the OR game 14d. T in this work
Assuming that the output of the FF 15 is switched at the rising edge of the 2-second drive pulse, the Q output outputs an H signal, and the mutual output outputs an L signal, the AND gate 16a is turned on, so the 2-second drive pulse is It passes through Antgame) 16a, Oage) 16C, inverter 27 and OR gate 2.
1 to the drive circuit 26, and the rotor 69 is driven to fast forward every 2 seconds. Next, the coil opening/closing pulse for 2 seconds is applied to the AND gate 24.25 via the AND gate 26, but since the AND gate 24 is in the ON state due to the Q output which is the H signal of the TFF 15, the 2-second coil opening/closing pulse is applied to the AND gate 24.25. The second coil opening/closing pulse passes through the AND gate 24'i and is applied to the drive circuit 26 via the OR gate 21. Therefore, at one end of the coil 28, a whisker-shaped induced voltage as shown in FIG. Similarly, when the rotor 69 rotates normally, an H signal is output from the induced voltage detection circuit 29, and the rotor 69
If the motor does not rotate normally, the induced voltage detection circuit 29 outputs an L signal.

When the rotor 69 rotates normally and an H signal is output from the induced voltage detection circuit 29, this H signal is transmitted to the AND gate 26.
, 5 through the AND gate 60 which is turned on by the 2-second coil opening/closing pulse that has passed through the OR gate 32.
It is applied to the reset terminal R of RFF31. Therefore 5
The Q output of the RFF 31 is switched to an L signal and applied to the AND gate 35. Therefore, the AND gate 65 becomes OFF state, and even if a clock signal CL as shown in FIG. 2 (gl) is subsequently applied to the AND gate 65, it cannot pass.
The output Q of the 5RFF36 is an L signal. Therefore, the rotor 39 will be driven by the 2-second drive pulse in the next step.

Next, a case will be described in which the voltage further decreases or the rotor 69 stops rotating normally due to some kind of load. In this case, the 2-second movement mode is switched to the variable-speed 2-second movement mode, but to explain in detail, the induced voltage does not exceed Vth of the induced voltage detection means 29, and therefore the output of the induced voltage detection circuit 29 is also low when detecting induced voltage.
Therefore, the output of the output terminal Q of the 5RFF 31 remains at the HEN signal set by the 2-second motion pulse. Therefore, the AND gate 35 is in an on state, and at the moment when the clovk signal CL is applied, an H signal is applied to the set/soto terminal S of the 5RFF 36, and the Q output of the 5RFF 66 is switched and held at the H signal. Therefore, the AND gate 14C is turned on and the AND gate 18.23 is turned off, so that the 2-second shift drive pulse passes through the AND gate 14c and passes through the OR gate 14d to the TFF 15 and the AND gate 16a.
, 17a. If the output of the TFF 15 is switched at the rising edge of the 2-second shift drive pulse, and the Q output becomes an H signal and the ζ output becomes an L signal, the AND gate 16a is turned on, so the 2-second shift drive pulse becomes The drive circuit 26 passes through the AND gate 16a and passes through the OR gate 16c1 inverter 27 and OR gate 21.
is applied to drive the rotor 69. In the next step, the output of TFF15 is switched and this time
7b is turned on, and the 2-second shift drive pulse that passes through the AND gate 17b is output to (or game) 17C, inverter 2
7 and the OR gate 22 and is applied to the drive circuit 26 to drive the rotor 39. Thereafter, the same driving as described above is performed.

At this time, one end of the coil 28 has a
A signal with a different pulse interval is generated every 2 seconds.

However, in this embodiment, since the pulse widths of the 2-second drive pulse and the variable speed 2-second drive pulse are the same, the rotor 69 still does not rotate normally, the second hand does not move, and a time delay occurs.

Next, a case will be explained in which the watch is exposed to light and the voltage of the power source 9 becomes high or the load becomes light (and the watch starts to move).

In this case, the watch moves in the 2-second movement mode, which is similar to a variable-speed movement.The user becomes aware of the fact that it has stopped in the past and realizes that the time must be adjusted. - When an external operating member (not shown) such as a switch is pulled out, the switch SW shown in FIG. Therefore, 5I
The Q output of tFF36 is switched to an L signal and held.

After that, when you adjust the time and push in the external operation member, the
The edge SW is connected to the power supply ■88, so 5RFF36
The L signal will be output and held from the output terminal Q of , and if the power supply voltage is above a predetermined voltage, the hand will move for 1 second, and if the power supply is below the predetermined voltage, the hand will move for 2 seconds. become.

Next, the induced voltage detection sensitivity adjusting means, which is the gist of the present invention, will be explained in detail.

In the above explanation, it was briefly explained that when the rotor 39 rotates normally during the 2-second movement, the induced voltage exceeds Vth of the induced voltage detection circuit 29, and does not exceed Vth unless it rotates normally.
Second hand movement is a hand movement mode when the power supply voltage is low. In this mode, the rotor 69 has difficulty rotating (easily stops) with the same pulse width as the normal drive pulse. Therefore, it is necessary to make the pulse width wider than the normal drive pulse. If the pulse width is widened, the rotor 69 rotates normally and vigorously when the power supply voltage is close to a predetermined power supply voltage, but it becomes difficult to generate an induced voltage.This is because the pulse width is long. This is because the pulse is applied even after the rotor 69 rotates one step, so a braking force is applied, and free vibration of the rotor 39 is prevented.

FIG. 3 shows the state of the induced voltage generated when the detection sensitivity adjustment means 36 is set to low sensitivity during the 2-second movement as in the 1-second movement. Even though it is rotating normally, the whisker-like induced voltage is Vth of the induced voltage detection means 29 as described above.
It is possible to exceed the rotation speed, and it will be detected as non-rotating. As a result, even though there is no time lag, the speed change hand moves at 2 second intervals, resulting in the user having to make five adjustments to the timing due to the time lag.

In the present invention, Trl and 'l'rt of the detection sensitivity adjustment means 36 shown in FIG. 2 are turned off when the hands move for 2 seconds, unlike when the hands move for 1 second. That is, by switching to high sensitivity, the whisker-shaped induced voltage exceeds vth of the induced voltage detection means 29 as shown in FIG. 4, and when the rotor 69 is rotating normally, rotation can be detected correctly. .

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, when the power supply voltage is low, the pulse width is lengthened (to prevent the clock from stopping), and the drive pulse Since the detection sensitivity is switched according to the difference in the pulse width of the rotor, it is possible to accurately detect rotation or non-rotation of the rotor, and various operations can be performed based on this information, which has a great effect. be.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of an electronic timepiece according to the present invention, and FIG.
The figure shows the output voltage waveform of the main part of the circuit diagram shown in Figure 1, and Figure 3 shows the coil when the detection sensitivity adjustment means for adjusting the detection sensitivity of the induced voltage is not switched during the 2-second movement. Figure 4 is a diagram of the voltage waveform generated at one end of the coil when the detection sensitivity adjustment means is switched during 2-second movement, and Figures 5 and 6 are diagrams explaining the operation of the rotor. be. 6... Normal drive pulse generation circuit, 4...
・Correction drive pulse generation circuit, 5...2-second drive pulse generation circuit, 6...2-speed variable speed drive pulse generation circuit, 9...Power supply, 13... ...Power supply voltage detection circuit, 14...Pulse selection circuit, 29...Induced voltage detection circuit, 66...Detection sensitivity adjustment means.

Claims (1)

[Claims] It has an induced voltage detection means for detecting an induced voltage generated by free vibration of the step motor after the application of the normal drive pulse is finished, and determines whether or not the rotor rotates based on the output signal of the induced voltage detection means, In an electronic clock that drives the rotor with a corrected drive pulse when a non-rotation determination is made, a power supply voltage detection circuit, the normal drive pulse, and a low-voltage drive pulse whose pulse width is normally wider than the drive pulse are used. and a detection sensitivity adjustment means for adjusting the detection sensitivity of the induced voltage detection means, and when the power supply voltage falls below a predetermined voltage, the detection from the power supply voltage detection circuit An electronic timepiece characterized in that the pulse selection circuit is controlled by a signal so that the low voltage drive pulse is switched and outputted, and the induced voltage detection means is switched to a high sensitivity state.