GB2067795A - Improvements in or Relating to Stepping Motor Driven Electronic Timepieces - Google Patents

Abstract

In an electronic timepiece actuated by an electric stepping motor normally driven by pulses 20 of successively opposite polarities, and having a detecting circuit for detecting whether the motor has rotated or not in response to an applied pulse, when the response of the detecting circuit is that appropriate to the condition of non-rotation, there are applied to the motor two successive correction driving pulses 22, 23 of successively opposite polarities and each of greater width than that of a normal driving pulse 20, the first correction pulse 22 being of opposite polarity to the immediately preceding normal driving pulse 20b. The arrangement is stated to avoid errors which would otherwise occur if the detecting circuit fails to detect a non-rotation. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to Stepping Motor Driven Electronic Timepieces This invention relates to stepping motor driven electronic timepieces and more particularly, though not exclusively, to stepping motor driven wrist watches.

The invention is illustrated in and will be explained with reference to the accompanying drawings in which: Figure 1A is a perspective view of a stepping motor suitable for driving the time indicating means (usually hands and a calendar) of an electronic timepiece in accordance with the present invention; Figure 1 B is a time chart showing driving pulses as commonly employed for driving the stepping motor of a conventional stepping motor driven electric timepiece;; Figure 1 C is a time chart showing correction driving pulses as used for driving the stepping motor of a known stepping motor driven electronic timepiece in which economy of overall power consumption is achieved by normally driving the motor by driving pulses of just sufficient width to overcome the normal load but driving it by correction pulses of greater width when the normal pulses are insufficient to achieve correct driving of the motor; Figure 2 is a block diagram of one embodiment of the present invention; Figure 3 is a time chart showing driving pulses used for driving the stepping motor of a timepiece in accordance with the present invention and as illustrated by Figure 2; Figure 4A is a circuit diagram of the divider and waveform producing circuits in the embodiment illustrated by Figure 2;; Figure 4B is a time chart showing output signals from the circuitry shown in Figure 4A; Figure 5 is a circuit diagram of the controlling circuit in the embodiment shown in Figure 2; Figure 6 is a circuit diagram of the driverdetecting circuitry in the embodiment shown in Figure 2; Figures 7A, 7B, 7C and 7D show the rotor and the neighbouring part of the stator of the stepping motor and are provided for assisting in an explanation of the operation of the motor; and Figures 8A and 8B show induced voltage waveforms produced as the results of rotor movement and are also provided for explanatory purposes.

Figure 1A is a perspective view of a conventional two-phase stepping motor as often used for driving the hands of a known electronic analog timepiece and which can equally weli be used for driving the hands of a timepiece in accordance with this invention. The motor has a stator 1, a two-pole permanently magnetised rotor 2, and a driving or energising coil 3. The motor can be driven by applying driving pulses such as the pulses shown at 4a and 4b in Figure 1 B, to the coil 3.Successive pulses are of opposite polarities and the construction of the motor is such that each successive pulse causes the rotor to rotate through 1 800 in the same direction, so long, of course, that the pulses are enough to overcome the load on the motor and to cause it to be in what is herein termed the "rotation condition"-that is to say with the rotor poles correctly positioned for the next half revoltuion to occur when the next pulse is applied-after each driving pulse. If, however, by reason of a heavy load on the motor, or for any other reason, the rotor is not correctly rotated through a half-revolution by any pulse, the next pulse will find the rotor poles in the wrong position for the next half revolution in the same direction to occur. This condition is herein termed the "non-rotation condition".Maintenance of the rotation condition can be obtained by making the pulses wide enough to overcome the maximum load occurring when the timepiece is in use. In a timepiece having a calendar, maximum load occurs when the calendar is being changed-an operation which usually takes about 6 hours. 1 second pulses of a width of 7.8 msec, as shown in Figure 1 B, may be taken as wide enough to meet the maximum load in an analog electronic wrist watch with hands and a calendar but, because maximum load occurs only for a relatively small part of the time, the use of pulses of such a width all the time results in an undesirably and unnecessarily large overall power consumption.

Substantial reduction in overall power consumption may be achieved by adopting what is herein termed the "correction driving method".

In this method normal pulses, of insufficient width to overcome the maximum load-e.g. pulses of a width of 3.9 msec-are used normally, i.e. most of the time, but, if the load increases so much above normal (e.g. during calendar changing) as to cause the non-rotation condition to occur, this is detected and a wider (correction) pulse is applied to overcome the load. The correction driving method is illustrated by Figure 1 C. Here the pulses 5a and 5b are the narrower, normal, driving pulses.Whether the rotation or nonrotation condition exists after the motor has been driven by a pulse is detected by taking advantage of the fact that the voltage induced in the coil by rotor movement during a detection time interval 6a or 6b will be quite different if the non-rotation condition exists from what it is if the rotation condition exists. If the non-rotation condition is detected (as it is assumed to have been in the detection interval 6b in Figure 1 C) a wider (7.8 msec) correction pulse is applied to produce a sufficient torque from the motor to overcome the load.

The correction driving method is exceedingly advantageous from the point of view of achieving a low overall power consumption, a very important matter in a battery driven wrist watch.

However, with the correction driving method as so far described, there remains the disadvantageous possiblity that the rotor may be vibrated by a shock or impact applied to the timepiece during a detection time interval, and this may cause such voltage to be induced in the coil that the detection circuit operates in error i.e.

mis-detection occurs. If, in consequence of such mis-detection, a normal pulse is applied to the motor when, if mis-detection has not occurred, a correction pulse would have been applied, the result is to delay the advance of the rotor, and therefore the time indicated by the timepiece, by a matter of 2 seconds (assuming successive driving pulses at 1 second intervals-the usual case). This is a serious disadvantage in accurate quartz crystal timepieces which are often required to have a monthly time error of 15 seconds or less.

The object of the present invention is to avoid this defect and prevent the occurrence of error in indicated time (in the foregoing example of 2 seconds) as the result of mis-detection by the detection circuit of a timepiece employing the correction driving method.

According to this invention an electronic timepiece comprises time indicating means actuated by a stepping electric motor normally driven to advance in steps in response to the application thereto of periodic normal driving pulses of successively opposite polarities; a detecting circuit for detecting, after a driving pulse has been applied to the motor, whether the motor is in the condition of rotation or in the condition of non-rotation; and means, operated with the response of the detecting circuit is that appropriate to the condition of on-rotation, for applying to the motor two successive correction driving pulses of successively opposite polarities and each of greater width than that of a normal driving pulse, the first of these correction driving pulses being of opposite polarity to the immediately preceding normal driving pulse.

Figure 2 is a block diagram of one embodiment of the present invention. Referring to Figure 2, 10 is a quartz crystal controlled time base oscillator producing a time base reference signal of (for example) 32768 Hz. Block 11 is a frequency divider which divides the 32768 Hz signal down to a 1 Hz signal and'consists of 1 5 flip-flop stages. Block 15 is a waveform producing circuit which comprises a number of gates of different types and which produces, from signals taken from selected different points in the divider 1 various different required waveforms. Block 12 is a controlling circuit, also consisting of gates, which supplies normal driving pulses and correction driving pulses to block 13 which includes a driving circuit and a rotation condition detecting circuit and which provides feed-back signals to the circuitry in block 12.The driving circuit in block 13 includes a MOSFET having a current capacity sufficient to supply the current necessary for driving the stepping motor (represented by block 14). The detecting circuit in block 13 includes the MOSFET in the driving circuit, a resistance, comparator means, and a source of reference voltage. The output leads from the driver-detecting circuit block 13 are connected to the two ends of the coil of the stepping motor 14 which drives the time indicating means 1 7 (usually hands and a calendar) of the watch through suitable gearing represented by block 1 6.

The circuitry in the blocks 11, 15, 12 and 13 will be described later.

Figure 3 illustrates the correction driving method employed in the present invention. 20a and 20b are normal driving pulses of 3.9 msec width which are wide enough to cause the motor to produce just sufficient torque to rotate correctly against the normal load i.e., in a watch with a calendar, during the (roughly) 1 8 hours per day when the calendar is not being changed.

Just after each of these normal pulses is produced, i.e. in detection time intervals 21 a and 21 b, the rotation or non-rotation condition, whichever it may be, is detected. Assuming that the rotation condition exists after the normal pulse 20a, and is detected in the interval 21 a, a correction pulse will not be produced but the oppositely phased normal driving pulse 20b will be produced after one second.If, after this, the signal from the detection circuit produced in the detection time interval 21 b is appropriate to the existence of the non-rotating condition, a correction pulse 22 in the opposite phase to the normal driving pulse 20b and with a width of 7.8 msec is initially produced as a first correction pulse, and, 7.8 msec after this, a second correction pulse 23 in the same phase as the normal driving pulse 20b and having a width of 7.8 msec is produced. Accordingly, ven if misdetection by the detecting circuit occurs, the motor will be correctly rotated and the error, previously mentioned, of two seconds in the indicated time will not occur. The reason why this desirable result is achieved will now be explained.

Suppose that, by reason of some external shock suffered by the timepiece during the detection time interval 21a, a signal as if the rotor were in the rotating condition is induced in the coil, and the detecting circuit consequently erroneously judges that the rotor is in the condition of rotation although in fact it is not, because it has not been rotated through a half revolution by the pulse 20a. Naturally a correction pulse is not produced and the next normal driving pulse 20b after one second is produced. However, because of the position of the rotor poles in relation to the stator (because the rotor has not actually been rotated through a half revolution) the normal driving pulse 20b cannot rotate it.

Provided that a shock sufficient to rotate the rotor is not applied during the next detection time interval 21 b, detection occurs in the ordinary way and the detection circuit judges that the rotor is in the condition of non-rotation. Subsequently to this, the first correction pulse 22 is produced. This can rotate the rotor correctly since the phase or polarity of this pulse is opposite to that of the driving pulse 20b. Thus the first correction pulse 22 corrects the driving of the rotor. Thereafter, while vibration of the rotor is ceasing i.e., after 7.8 msec in this case, the second correction pulse 23 is applied to the coil. Since the phase of the second correction pulse is the same as that of the normal driving pulse 20b, it can rotate the rotor.

Thus, the condition of non-rotation of the rotor with respect to the normal driving pulse 20b is corrected by the second correction pulse 23.

On the other hand, if mis-detection has not occurred, the first correction pulse 22 has no effect on the rotation of the stepping motor. This is because, even if the rotor cannot be rotated by the normal driving pulse 20b, the position of the rotor poles with respect to the stator will be such that the first correction pulse 22 cannot rotate the rotor. The increase in current consumption due to effecting correction by increasing the number of correction pulses in this way is very small and can be ignored, because the normal driving pulse width is chosen at a value such as to minimize the probability of correction pulses having to be generated.

Figure 4A is a diagram of the circuitry of the frequency divider 11 and the waveform producing circuit 1 5 of Figure 2.

The frequency divider 11 consists of fifteen flip-flops (only 11 are actually shown in Figure 4A) of the negative edge trigger type and waveforms as shown in Figure 4B are produced at the output terminals PD 1, PD2, PS 1, PN, and PS2 of Figure 4A. The Q outputs from the flip-flop stages 012, Q1 3, 014 and Q1 5 are fed as inputs to a NOR gate 40, the pulsed output from which has a pulse width of 62.5 msec. The 0 outputs from the stages Q9 and Q10 are fed as inputs to a NOR gate 33 the third input of which is fed from the 0 output terminal of the eleventh flip-flop through an inverter 30 so that this input is 011.

The output from NOR gate 33 is fed to one input of an AND gate 41 the other input of which receives the output from the NOR gate 40. The output from the AND gate 41 is the PD1 pulse shown in Figure 4B.

A NOR gate 34 is connected to receive the inputs Q9, 010 and Q11 (the last mentioned via the inverter 30) and the output from 34 is fed to one input of an AND gate 42 the other input of which receives the output from the NOR gate 40.

The output from 42 is the PD2 pulse shown in Figure 4B.

Outputs 09 and 010 are fed as inputs to an AND gate 32, the output from which and the 011 output are fed respectively to the inputs of a NOR gate 35 the output from which is fed to one input of an AND gate 43 the other input of which receives the output from the NOR gate 40. The output of the AND gate 43 is a waveform having a one second period and a pulse width of 23.4 msec.

The Q8 and 09 outputs are fed to the respective inputs of an AND gate 36, the output from which together with the Q10 output, are fed to the respective inputs of an OR gate 37. The output from 37 together with the output from the AND gate 43 are fed to the respective inputs of an AND gate 44, the output from which is the pulsed waveform PS1 shown in Figure 4B.

The Q8, Q9 and O10 outputs are fed to the respective inputs of a NOR gate 38, the output from which, together with the output from the AND gate 43, are fed to the respective inputs of an AND gate 45. The output from 45 is the pulsed waveform PN shown in Figure 4B and which has a period of 1 second and a pulse width of 3.9 msec.

The Q5 output is fed via a NOT gate (inverter) 39 to one input of an AND gate 46, the other input of which receives the output from AND gate 43. The output from 46 is the waveform PS2 shown in Figure 48 and is a waveform of 0.98 msec period produced once very second for 23.4 seconds.

The output signals at the terminals PD1, PD2, PS1, PN and PS2 (Figures 4A and 4B) are fed to the controlling circuit 12 (Figure 2) the circuitry of which is shown in Figure 5.

Referring to Figure 5 the terminals PN, PD1, PD2, PS1 and PS2 correspond with the similarly referenced terminals in Figure 4A. The terminals DS1 and DS2 receive fed back input signals from the similarly referenced terminals of the driverdetecting circuit block 1 3 (Figure 2). Output signals GP1, GN1, GS1, GP2, GN2 and GS2 from the terminals so referenced are fed to corresponding referenced terminals in the driver detecting block 1 3.

The signals PS1 and PS2 are fed to the respective inputs of an AND gate 51 and the output from which is fed to one input of each of two AND gates 52 and 53. The detection signals DS1 and DS2 are respectiely fed to the remaining inputs of AND gates 52 and 53, the outputs of which are fed to the respective inputs of an OR gate 54. The output from 54 is pased to the set terminal S of an SR flip-flop 55 which is set by a rotating condition detecting signal from DS1 or DS2 only when the output from an AND gate 51 is HIGH ("H").

Voltage is induced in the motor coil by rotational movement of the rotor (due to inertia and the magnetic forces) when the rotor is rotated by a normal driving pulse PN, and an "H" level signal is produced at DS1 or DS2 to set the SR flip-flop 55. Accordingly the Q signal of the SR flip-flop 55 will be LOW ("L"). The 0 terminal of 55 is connected to one input of each of three AND gates 57, 58 and 59 and the outputs from these gates will therefore be ;'L". The correction pulses PD1 and PD2 are fed to the respective inputs of an OR gate 50 the output from which is fed to the remaining input of AND gate 57. The normal driving pulse PN and the output from the AND gate 57 are fed to the respective inputs of an OR gate 60 the output from which is fed to one input of each of two AND gates 64 and 66.The output from the OR gate 60 supplies current to the stepping motor when this output is at "H" level.

The correction pulse PD1 is fed to the remaining input of AND gate 58, the output from which therefore corresponds to the correction pulse PD1 only when the SR flip-flop 55 is not latched. The output from the AND gate 58 is fed to one input of each of two EX. OR gates 62 and 63, the remaining inputs of which are respectively connected to the Q and Q outputs of a flip-flop 61. As will be seen the output from each of the EXCLUSi'XE-OR gates 62 and 63 can be reversed by output from the flip-fiop 61 only when the output from the AND gate 58 is "H". The normal driving pulse PN is used not only as the normal driving pulse but is also applied to the reset terminal R of the flip-flop 55 to act as a reset signal therefor.The pulse PN is also fed through a NOT gate 56 to tne clock terminal CL of the flipflop 61 to serve as a negative edge trigger pulse to change the stage of said flip-flop 61 every second. The said PN signal is also fed via 56 to the remaining input of AND gate 59 to prevent a detecting pulse from being produced while the stepping motor is being driven.

The output from the AND gate 59, is used as a detecting pulse for detecting the condition of rotor rotation and is fed to one input of each of two AND gates 65 and 67. The output from EX OR gate 62 is fed as shown to the AND gates 64 and 65 and the output from the EX.OR gate 63 is fed as shown to the AND gates 66 and 67.The output from the AND gate 64 is fed via inverter 68 to the terminal GP 1; the output from the AND gate 65 is fed to the terminal GS1 ; the output from the AND gate 66 is fed via inverter 69 to the terminal GP2; and the output from AND gate 67 is fed to the terminal GS2. The outputs from the AND gates 64 and 65 are fed to the respective inputs of a NOR gate 70 the output of which is fed to the terminal GN 1, and the outputs from the AND gates 66 and 67 are fed the respective inputs of a NOR gate 71 the output from which is fed to the terminal GN2.

Figure 6 is a diagram of the circuitry in the driver-detecting block 13 of Figure 2.

Referring to Figure 6, 80 and 82 are P-channel electric field effect transistors (P-MOS) and 81, 83 are N-channel electric field effect transistors (N-MOS). These are used in a driver circuit for driving the stepping motor. In this driver circuit the drains of the P-MOS 80 and of the N-MOS 81 are connected together and to an output terminal OUT 1 for the stepping motor and also to the drain of an N-MOS 85 through a resistance 84.

Similarly, the drains of the P-MOS 82 and the N MOS 83 are connected together and to an output terminal OUT 2 for the stepping motor and also to the drain of an N-MOS 87 through a resistance 86.

The signal at OUT 1 (this will depend upon whether the motor is in the condition of rotation or of non-rotation and will be markedly different in the two cases) is fed to the + terminal of a comparator 94. The comparator 94 compares the signal at OUT 1 with a reference voltage difference VDDV5S which is produced by means of a potentiometer including resistances 89 and 90, an N-MOS transistor 93 arid which is applied to the -- terminal of comparator 94. The comparator produces at terminal DS1 an "H" level signal only when the signal at OUT 1 is larger than VDDVS5. The signal at OUT 2 is also treated in the same way by means of a second comparator 92 the output of which is connected to terminal DS2. A NOR gate 88, the N-MOS 91.

an N-MOS 93 and an N-MOS 95 prevent current from flowing in the circuit except when detection is taking place.

For completeness of explanation the principle employed for detecting whether the motor is in the condition of rotation or of non-rotation will now be desonbed with the aid of Figures 7A to 7D and Figures SA and 8B.

Figures 7A and 7B show diagrammatically the rotor and part of the stator of the motor. 2 is the rotor with its two permanently magnetised poles N and S and 1 is the part of the stator which surrounds the rotor.

Figure 7A shows the rotor in its rest position. In this position, the line joining the poles N and S is substantially at right angles to a line joining two diametriallyopposite recesses 101a and 101h formed in the stator and which determine the rest position. The stator also has diametrically opposite recesses 1 00a and 100b which make the stator (whlch is integrally formed) magnetically saturable where these recesses occur. The angular position of the rotor in this rest position is defined by the angle 0.

When a normal driving pulse PN is applied to the coil 3, (see Figure 1) the stator 1 of the motor becomes magnetized as shown by the letters N, S on the stator in Figure 7B and the rotor 2 starts to rotate as shown by the arrow 102. When this happens, the P-MOS 82 and the N-MOS 85 are turned ON and current flows through the coil in a loop circuit which includes these transistors and which we will call Loop A.

The normal driving pulse is of 3.9 msec pulse width and ceases before the rotor 2 completes a half revolution. However the rotor movement continuous by reason of its inertia and the effect of its magnetic poles. If, however, by reason of a load which is too large in relation to the driving power (or for any other reason) the rotor cannot correctly perform its half revolution it will return, by reverse rotation as shown by the arrow 103 in Figure 7C, to its original initial rest position and - stop there after a littie damped vibration. In order to detect the voltage induced in the motor coil by the attenuated vibration, the N-MOS 83 and the N MOS 87 (Figure 6) are alternately turned ON. This inserts the resistance 86, which is of large value at both ends of the coil, in the case in which current flows from the resistance 86 to the N MOS 87, and the induced current sets up a voltage across the resistance in a loop circuit which we will call Loop B and a voltage which we will call VRS is developed at the terminal OUT 2 (Figure 6). The waveform of this voltage is shown by the broken line 105 in Figure 8A.

However, even if the N-MOS 81 and the N MOS 87 are turned ON, current passes through the N-MOS 83 as a parasitic diode which should have been turned OFF when the reverse current flows through the coil, and only a very small current will flow in the large resistance 86. When the N-MOS 81 and the N-MOS 83 are turned ON, both ends of the coil are shorted by these transistors. The circuit loop in operation here we will call Loop C. It will be observed from Figure 8A that the negative voltage is clamped at -0.3 V by waveform 105, the N-MOS 82 acting as a diode in LOOP C.

In Figure 7C, power is consumed in the Loop C during reverse rotation of the rotor, and the rotor therefore stops almost immediately owing to the large attenuation of its vibration, and hardly any positive voltage is developed, as will be seen from the waveform 105 in Figure 8A.

Next, when the rotor 2 is rotated as shown in Figure 7D, a voltage waveform as shown by the full line curve 106 in Figure 8A occurs between the terminals Vss and OUT 2 (see Figure 6).

Detection of the rise in positive voltage in the waveform 106 effects detection of the condition of rotation of the motor. However because the values of voltage in the waveforms in Figure 8A are too small for convenient and reliable direct detection, amplification of the signals is adopted as will now be explained.

The N-MOS 87 and the N-MOS 83 are alternately changed over during a time interval for detection. In Figure 8A, Loop B and Loop C are alternately changed over during the time interval of the positive voltage. A large current flows in Loop C, which is of low impedance, and current flows into the resistance 86 at the instant Loop C is replaced in circuit by Loop B. Because the inductance of the motor coil acts to keep the current flowing, the waveform 106 in Figure 8A is changed over to a waveform as shown in Figure 8B, and the peak current attains a value several times greater than before. This enhanced voltage waveform is quite easy to detect and, accordingly, whether the motor is in the condition of rotation or of non-rotation is easily detected by the comparator means.

Although the principle of operation as so far described has been described and illustrated with reference to polarity occurring within one second, the polarity period in the embodiment illustrated is actually of a period of two seconds and accordingly the P-MOS 80 and the N-MOS 83 in the Loop A are turned ON, the N-MOS 83 and the N-MOS 85 in the Loop B are turned ON, and the N-MOS 83 and the N-MOS 81 in the Loop C are turned ON at the next second. It will be seen that the operations of the Loops A, B and C are therefore similar in two successive seconds.

As will now be understood, if, as a result of shock being applied to the rotor while it is driving, a mis-detection occurs and the detection circuit judges the motor as being in the condition of rotation although actually it is not, when the next (reversed) normal driving pulse is applied to the motor it cannot be rotated thereby. However, since the detecting circuit will judge the motor to be in the condition of non-rotation on this occasion, it will be rotated through 1 800 by the first correction pulse PD1 of opposite phase and the rotation will be corrected before one second, and the hands will then be advanced again by the second correction pulse PD2, so that the time indicated after this will be correct.

As will now be understood the indicated time will first be one second slow but will then be advanced by two seconds at the next step.

Although such stepping is abnormal when compared with the usual stepping of one step per second, this does not really matter in practice for, in any case, the probability of mis-detection is exceedingly small. The important advantage is that, when mis-detection does occur, it does not result in a permanent error of retardation in the indicated time, for the initial loss of one second is compensated for and corrected in the following second.

Claims (10)

Claims

1. An electronic timepiece comprising time indicating means actuated by a stepping electric motor normally driven to advance in steps in response to the application thereto of periodic normal driving pulses of successively opposite polarities; a detecting circuit for detecting after a driving pulse has been applied to the motor, whether the motor is in the condition of rotation or in the condition of non-rotation; and means, operated when the response of the detecting circuit is that appropriate to the condition of nonrotation, for applying to the motor two successive correction driving pulses of successively opposite polarities and each of greater width than that of a normal driving pulse, the first of these correction driving pulses being of opposite polarity to the immediately preceding normal driving pulse.

2. A timepiece as claimed in Claim 1 wherein the correction driving pulse width is at least approximately twice that of a normal driving pulse.

3. A timepiece as claimed in Claim 1 or 2 wherein the intervals between the aforesaid first driving correction pulse and the immediately preceding normal driving pulse and between the aforesaid successive correction driving pulses are each at least approximately equal to the correction driving pulse width.

4. A timepiece as claimed in any of the preceding claims and comprising a time base oscillator of relatively high frequency; a multistage frequency divideRfor dividing down the output of said oscillator to a predetermined relatively low frequency; a waveform producing circuit comprising a plurality of gates and fed with signals from a plurality of points in said divider for producing from said signals normal driving pulses and correction driving pulses for driving the motor and detection pulses for determining the times at which the detecting circuit is operative to detect whether the condition of rotation or of nonrotation exists in the motor; a driver circuit; and a controlling circuit to which the pulses produced from the waveform producing circuit are fed and which is controlled by detection signals from the detecting circuit and which controls the driver circuit to cause it normally to supply normal driving pulses to the motor but to supply thereto the aforesaid two successive correction pulses when a detection signal appropriate to the condition of non-rotation is delivered by the detecting circuit.

5. A timepiece as claimed in Claim 4 wherein a transistor, common to both the detecting circuit and the driver circuit, is used both for providing driving pulses for the motor and in the detection of whether it is in the condition of rotation or nonrotation.

6. A timepiece as claimed in any of the preceding claims and having a frequency divider and a waveform producing circuit substantially as herein described with reference to Figures 4A and 4B of the accompanying drawings.

7. A timepiece as claimed in Claim 6 and having a controlling circuit substantially as herein described with reference to Figure 5 of the accompanying drawings.

8. A timepiece as claimed in Claims 6 and 7 and having driver and detecting circuits substantially as herein described with reference to Figure 6 of the accompanying drawings.

9. A timepiece as claimed in any of the preceding claims and having a stepping motor constructed and operating substantially as herein described with reference to Figures 1 A and Figures 7A, 78, 7C, 7D, 8A and 88 of the accompanying drawings.

10. An electronic timepiece comprising: an oscillator for producing a time reference signal; a frequency divider for dividing said reference signal; a wave shaping means for composing pulses necessary for driving a stepping motor and for detecting a rotor rotation; a controlling means for controlling the stepping motor drive by a signal from a driver-detecting means, said driverdetecting means including a transistor for driving the stepping motor, detecting a rotation condition or a non-rotation condition of the rotor; and a stepping motor driven by a normal driving pulse; wherein said controlling means immediately produces, via said driver-detecting means, a first correction pulse of an opposite phase to said normal driving pulse, and further produces a second correction pulse of an in-phase to said normal driving pulse, when said driver-detecting means judges said rotor being in a non-rotation condition, whereby the stepping motor is controlled precisely.