JPS6138423B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention primarily relates to a method for driving a step motor for an electronic wristwatch. As a method of reducing power consumption, such as ultra-compact step motors for electronic watches, the step motor's own electricity is used.
In addition to improving mechanical conversion efficiency, the rotor is normally driven with low power, and if the rotor does not rotate properly for some reason, it is quickly re-driven with higher power than usual. A so-called correction drive system has been devised. When adopting this correction drive method, the important thing is how to detect whether the rotor is rotating or not, and how to ensure that it is difficult to stop due to external conditions such as magnetic resistance compared to the conventional fixed pulse drive method. The question is whether to do so. FIG. 1A shows an example of a step motor that has been used to drive the hands of a conventional electronic watch and is also used in the present invention, and FIG. 1B shows a conventional step motor that drives a step motor with this structure. This is an example of an inversion pulse used for this purpose. By applying the drive pulse shown in FIG. 1B to the coil 3, the stator 1 is magnetized, and the rotor rotates 180 degrees due to the repulsion and attraction of the magnetic poles of the rotor 2. Conventionally, the length of the applied driving pulse has been selected to be such that the output of the motor can be guaranteed under all conditions that should be guaranteed for a watch. However, this requires allowances for calendar loads, high internal resistance of the battery, voltage drop at the end of life, etc., and it is therefore necessary to drive with a pulse width with some allowance. Therefore, we improved this method by driving the step motor with the last possible pulse length, which normally does not have much margin, and then equipped with a detection circuit that determines whether the rotor is rotating or not. A method has been proposed in which correction driving is performed using a pulse width conventionally used only when a determination is made. When detecting whether the rotor is rotating or not, it is difficult to install an external detector due to the cost, compactness, and thinness of the watch. A method has been used to determine whether the rotor is rotating or not, based on the characteristic that when the rotor is not rotating, the way the power is generated due to vibration of the rotor after applying a drive pulse is different. FIG. 3 shows the current waveform of a conventionally used step motor. The period a in FIG. 3 is the time during which the driving pulse is applied, and b is the current generated due to the induced current due to the vibration of the rotor after the driving pulse is applied. The waveform in Fig. 3 _b1 is the current waveform when the rotor is rotating, and _b2 is the current waveform when the rotor is not rotating. The drive circuit at this time is a circuit as shown in Fig. 4A, and 4 and 5 are inverters composed of an N-channel field effect transistor and a P-channel field effect transistor, and the coil 3 of the step motor is connected to the output of the inverter. Connected. After applying the drive pulse, the coil 3 is short-circuited by the transistor constituting the inverter, and at this time the third
The current shown in b in the figure flows, and a voltage equal to the product of the ON resistance of the drive transistor and the rotor oscillation current is generated. After converting this generated voltage into a voltage in the same direction through the transmission gate, 6 The voltage comparator compares the reference voltage and the peak voltage to determine whether the rotor is rotating or not, and if it is determined that the rotor is not rotating, corrective driving is performed. However, with this method, when a clock is inserted into an alternating magnetic field, the external magnetic field induces a voltage in the coil, so when determining whether the rotor is rotating or not rotating based on the induced voltage due to rotor movement, it is considered external noise. Since it is added to the detection signal, it causes erroneous detection, causing a rotor error and, in other words, a clock error. Figure 5 is a graph of the step motor drive pulse width and AC magnetic resistance.In order to reduce the power consumption of electronic watches, the drive pulse width is normally set to the lowest pulse width that can drive the step motor. Magnetic resistance with normal drive pulses is in the direction of deterioration, so in order to adopt this correction drive method in a watch and obtain the same magnetic resistance as before, it is necessary to have a more rigid magnetic resistance structure, and to reduce the current. However, for the anti-magnetic structure, a shield plate is added, which is disadvantageous for thinning and downsizing.
The cost also increased, and its benefits could not be fully exploited. The present invention detects when a watch enters a magnetic field,
In order to prevent the clock from stopping with the normal drive pulse width, the step motor is forcibly driven with a pulse width that is strong against external magnetic fields. This was done for the purpose of further improving magnetic resistance than fixed pulse driving. In the present invention, the voltage induced in the coil 3 is detected during the time when the rotor is not moving, that is, the time other than the period of drive pulse width a shown in FIG. If the signal is detected, it recognizes that the watch has entered a magnetic field, and fixes the next drive pulse width to the pulse width that makes it most difficult to stop due to the magnetic field, improving magnetic resistance. The feature of the magnetic field detection of the present invention is that the voltage induced in the coil of a step motor is detected without using a special magnetic field detection element such as a Hall element or a magnetoresistive element. The voltage induced in the coil 3 when the motor is exposed will be explained. FIG. 2 schematically depicts the coil and magnetic core 7 of the step motor. The coils used in step motors usually have an elongated shape, so the external magnetic field tends to concentrate on the magnetic core of the coil, and although it depends on the shape, the magnetic flux density is usually about 10 times higher. be. The voltage V induced in the coil 3 at this time is given by V=-n·dΦ/dt, where n is the number of turns of the coil 3 and Φ is the magnetic flux of the magnetic core 7.

[Table] When a magnetic core having the shape shown in Table 1 is used, assuming that the magnetic flux density inside the core is 10 times that outside, the magnetic flux Φ of the magnetic core is given by the following equation. Φ=10×S×B×sinωt... Here, S is the cross-sectional area of the magnetic core 7, and B is the peak value of the magnetic flux density of the alternating magnetic field. , from the formula, V=-10×n×S×B×ω×cosωt =-10×1×10 ⁴ (turn)×0.64×10 ^-4 (m ² )×B×10 ^-4 (wb/m ² ) ×2π×50(Hz)×cosωt =−6.4π×10 ^-2 ×B×cosωt [V] =−0.20×Bcosωt[V] Therefore, if the magnetic flux density B of the external magnetic field is
For 2 Gauss, V=-0.4cosωt [V]. Therefore, in order to detect the external magnetic field and control the drive pulses of the step motor, it is preferable to detect the voltage generated in this coil. Embodiment (1) The present invention is achieved by adding an alternating current magnetic field detection circuit to the correction drive method described above in the conventional method before applying a drive pulse. In the circuit of FIG. 4A, 93a is a drive circuit and 93b is a detection circuit. The external magnetic field can be detected by detecting the voltage generated in the coil 3 by the voltage comparator 6 through the transmission gate before applying the drive pulse. FIG. 4B shows that the gates of the P-channel field effect transistor and the N-channel field-effect transistor that constitute the inverter in FIG. 4A are separated.
Both are configured as 3-state inverters that turn OFF, and when detecting that the watch enters a magnetic field, coil 3 is opened and
This is intended to increase the sensitivity of magnetic field detection, and the other operations are the same as described above. FIG. 5 shows how the AC magnetic resistance changes when the drive pulse width of the step motor is changed. In the present invention, when it is detected that the magnetic field has entered the magnetic field, the peak point of the region 8 or
The step motor can be driven with a pulse width having good magnetic resistance in the region of 9, and AC magnetic resistance can be improved. At this time, the drive pulse time chart is shown in FIG. a is the normal drive pulse, b is the rotor rotation detection time, c is the correction pulse for re-driving when it is not rotating at a, b' is the rotor rest time, d is the magnetic field detection time, and d is the magnetic field detection time. When it is determined that the value is within the range, driving is performed with a pulse longer than the driving pulses a and c, as shown in e. Example (2) In the example shown below, improvements were made to the method of processing rotational and non-rotational information and the method of amplifying the detection signal. The circuit diagram shown in FIG. 7 shows the step motor drive section, rotor rotation/non-rotation detection section, and magnetic field detection section of this embodiment. In this example, by intermittently applying a voltage induced in a coil to a high impedance element, the entire circuit can be configured within an IC extremely easily without the need for a special amplifier. This is an excellent method for configuring it inside a watch because it only requires a slight increase in the size of the IC, there is no cost increase, and the operation is stable. The principle of detection signal amplification in this embodiment will be explained below with reference to the drawings. P-type MOSFET gates (hereinafter abbreviated as gates) 10 and 12 and N-type MOSFET gates (hereinafter abbreviated as gates) 11 and 13 in FIG. 7 are shown in FIG. 4A.
This is the gate that constituted the drive inverters 4 and 5 in the conventional example. Drive inverter output terminal 1
8 and 19 are connected to the coil 3 and, at the same time, via gates 14 and 15 to a high impedance element, here a detection resistor 16 formed of a resistor. A connection point 20 of the detection resistor 16 is connected to an input terminal of a binary logic element 17 having a predetermined threshold value. These form a drive circuit 93a and a detection circuit 93b. FIG. 8 shows each gate input signal. Section T ₁
is the timing at which the drive pulse is applied to the coil. That is, since only gates 10 and 13 are in the ON state, current flows from the power source along the path indicated by arrow 21. Next, as at timing T ₂ , gate 13,
Assume that only 14 is turned on. At this time,
A closed loop 22 including the coil 3 and the detection resistor 16 is formed. Coil 3 due to the movement of rotor 2 at this time
The induced voltage is e, the sum of the DC resistances of the coil 3 and gates 14 and 13 is r, and the resistance value of the detection resistor 16 is R.
Then, the potential V ₂₀ at the connection point 20 is V ₂₀ =eR/(R+r). Here, if R≫r, then V ₂₀ =e. Therefore, if the condition R≫r is satisfied, V ₂₀ can be regarded as the induced voltage in the coil 3. FIG. 10 shows an example of the waveform of _V20 . In this example, the detection resistance value is 5.0KΩ, the coil resistance is 3KΩ, and the number of turns is
At 10,000 turns, the step motor is almost under no load. Further, the relationship between this induced voltage and the rotation angle of the rotor is as shown in FIG. As the load on the step motor increases, the peak value of the induced voltage waveform gradually decreases while maintaining a similar shape, and the period of vibration becomes longer. In FIG. 11, the induced voltage at maximum load is shown as a, and the induced voltage when the rotor does not rotate due to overload is shown as b. In large load waveform a, the rotor rotation is slow, and
Since there is no vibration after one step rotation, there are few fluctuations in the induced voltage. Furthermore, in the non-rotating waveform b, a large peak voltage is induced in the negative direction when the rotor returns to its initial position. In order to detect rotation or non-rotation of the rotor according to the embodiment of the present invention, it is determined whether there is a peak q in the waveform shown in FIG. In the waveform shown in Figure 11, the peak voltage is generated at point P regardless of whether the rotor is rotating or not, so this section is ignored, and as the load increases, the voltage at point q in Figure 10 increases. However, during rotation, as shown in the waveform a in Figure 11, by detecting the presence or absence of the second peak voltage only during the time that the peak voltage occurs, it is possible to detect the non-rotating state. It can be distinguished from waveform b. Therefore, rotation or non-rotation of the rotor can be detected by detecting the voltage several milliseconds after the application of the normal drive pulse and detecting whether a voltage exceeding the reference voltage is generated within a few milliseconds. Next, the effect of intermittently switching between a high impedance element and a low impedance element, or in this embodiment a high resistance circuit and a low resistance circuit, after application of a drive pulse will be described. In the detection method shown in FIG. 7, in addition to the drive circuit,
Furthermore, a high-resistance detection resistor 16 is connected in series, and the induced current due to rotor motion is passed through the detection resistor 1.
It is smaller compared to the case without 6. Therefore, when induced voltage is generated due to rotor motion,
A high-resistance loop including the detection resistor 16 and a low-resistance loop using a drive transistor are switched. A timing chart at this time is shown in FIG.
By doing this, the current flowing through the coil changes rapidly. However, since the motor coil has a large inductance, it is unable to follow this sudden change and tries to continue to flow the current at low resistance through the detection resistor 16, generating a high voltage across the detection resistor 16. Therefore, the detection signal is amplified and a peak voltage of 1 volt or more is generated. Detailed theoretical considerations will be explained later. In this example, since a peak voltage of 1 volt or more can be obtained, the most sensitive
Since a range of about 0.5 to 1.0 volts can be used, comparator design becomes easier and the area of the comparator within the IC can be reduced. Furthermore, the binary logic element 17 shown in FIG.
It is possible to configure it with an inverter, which is the simplest component in a CMOSIC, and it is also possible to input it directly to the input of a flip-flop. In the embodiment of the present invention, if the detection resistor is too small, the detection signal becomes low, making it difficult to design a binary logic element for detection. Further, when the resistance value exceeds a certain value, the detected voltage does not increase because the electromotive force due to the movement of the rotor is constant. The experimental results show that in a motor with a coil inductance of 11 Henry and a coil DC resistance of 3KΩ,
After applying driving pulse, cycle 1msec, duty 50%
When switching the braking circuit with
At 20KΩ or more, a peak voltage of about 1.5 volts is generated, and when detected by a comparator with a threshold voltage of 0.5 volts, a detection signal is already output when the drive pulse reaches 90% of the output that cannot be rotated at 3.9 msec. be able to. For this reason, the pulse is usually kept short and the detection circuit of the present invention is added.
If the present invention is used in a low current drive system for a motor, etc., which immediately performs corrective drive using a pulse with a long drive time when it is determined that the load has become heavy based on the output, it will be extremely stable. The operation is simple, and the circuit configuration is simple.
The only factor that increases the area of the IC is a slight increase in the number of gate circuits for pulse synthesis.
Furthermore, the detection circuit does not include any capacitors, and the only analog element is the resistor, which has a very wide tolerance.Everything else is digitally processed, so its operation is extremely stable. Next, the effect of amplifying a signal by switching between a high resistance loop and a low resistance loop will be explained. FIG. 13 shows an N gate, and FIG. 14 shows its equivalent circuit. The switch 40 is activated by the gate signal.
Turn ON and OFF. 39 is ON resistance during driving,
Diode 41 is between the substrate and the drain.
Diode 41 and capacitor 4 by PN junction
2 is the sum of the PN junction capacitance between the substrate and the drain, the drain-gate capacitance, the patch capacitance, the stray capacitance, etc. If this equivalent circuit is replaced with the P gate and N gate of FIG. 7, and the battery is a large capacity capacitor and an ideal power source, the equivalent circuit of this detection method will be as shown in FIG. 15. 43 is a voltage V ₀ generated by an external magnetic field or rotor vibration, 44 is a coil that constitutes the motor and has an inductance L Henry, 45 is an internal resistance of the coil rΩ, 47 is a loop changeover switch, 46
is the ON resistance r ^N Ω of the N gate. However, since it is sufficiently smaller than the value of the coil resistance, this r ^N Ω is ignored here. 48 is a capacitance parasitic to the N gate and P gate, which is the sum of the parasitic capacitances of the N gate 24 and the P gate 22, and is C farad. 49 is a detection resistor RΩ, 50 and 52 are parasitic diodes between the N gate and P gate substrate and drain, 51 is a driving battery,
In a commonly used silver battery for watches, V _D =1.57V. The output voltage of the terminal 53 becomes the detection voltage V _R and is input to the voltage detection element. The changeover switch 47 is based on the equivalent circuit shown in Fig. 15.
The response when switching can be theoretically determined. a=1/2(r/L+1/CR), b=r+R/LC
R E=R/R+rV ₀ , ω=√｜ ² −｜,

[Formula] When a ² > b, V _R = E[1-{1/ω(a-DL/rb) sinhωt +coshωt}e ^-at When a ² = b, V _R = E{1- {1+at −DL/rbt)e ^-at } When a ² <b, V _R = E[1−{1/ω(a−DL/rb) sinωt +cosωt}e ^−at However, t ₀ is the low resistance loop Ground contact time, t is time. The V _R waveform of the above equation is as shown in FIG. 16A.
When calculating this V _R based on one example, L=1 Henry, C=75PF, R=150KΩ,
Under the conditions r = 2.8KΩ, V ₀ = 0.1V, to = ∞, the time to reach the peak voltage of V _R is approximately
30nsec, the peak voltage at this time is 4.2V,
The magnification is approximately 42 times, indicating that the detection signal can be easily amplified without using an analog signal amplifier. However, although this theoretical value assumes that to=∞ and that the time of the low resistance loop is infinite, in reality it switches between a high resistance closed loop and a high resistance closed loop. The time it takes to reach a steady voltage in a high resistance loop is relatively quick, but when switching to a low resistance closed loop, the time constant is large and it takes a long time to reach a steady voltage. To explain based on the above example, in the case of a closed loop with high resistance, V _RS becomes a nearly steady voltage in about 0.2 msec, but in the case of a low resistance loop, the time constant is τ = L / Determined by r, τ=3.9msec
Therefore, even if the low resistance loop continues for 3.9msec, the voltage will only be 63% of the steady voltage. When this method is used as an external magnetic field detector, the higher the amplification factor, the more sensitive the detection can be. The frequency of the most commonly encountered alternating magnetic field is
The commercial frequency is 50Hz or 60Hz, and the period is 20msec or 16.7msec, and there is an optimal switching time to detect the maximum strength magnetic field. FIG. 16B is a diagram when the high resistance loop time is 0.5 msec and the low resistance loop time is 1.5 msec under the above-mentioned conditions for an alternating current magnetic field of 50 Hz. In this case, the detection signal amplification factor is approximately 15 times the theoretical formula. The straight line 57 shown in FIG.
When switching 0.5 msec and high resistance loop 0.5 msec, the amplification factor is about 5 times. In this way, in order to detect alternating current magnetic fields at commercial frequencies, the high resistance loop and low resistance loop switching time cannot be taken very long, and if you try to increase the amplification of the detection voltage within that range, the It can be seen that the time for the low resistance loop should be longer than the time for the loop. As explained above, since the detection signal is amplified just by switching the circuit,
- There is no need for analog amplifiers, etc., which are difficult to create, inside the MOSIC, and AC magnetic fields can be detected using a comparator that determines whether the voltage is high or low relative to the reference voltage. In addition, since the amplification factor can be increased by more than 10 times, it becomes possible to make a judgment based on the threshold voltage of the C-MOS inverter.
There are also advantages in terms of overall circuit power consumption, circuit configuration, and IC area. Although this embodiment has been described using a resistor as an impedance element for detection, similar detection is possible using a capacitance component or an inductance component. In this embodiment, since all the detection elements are built in the C-MOSIC, the characteristics of the non-saturated portion of an active element called a buffer transistor are used as the low resistance element. Although the explanation has been made using an impedance element, there is no problem in using an active element like this. However, in actual configuration, as in the embodiment used in the present invention, the low resistance loop is the ON resistance of the buffer transistor, the high resistance loop is the diffused resistance in the IC, and the voltage detection element is a C-MOS inverter or ,
A comparator seems to be common. Further, in the description of the present invention, a high resistance is connected in the case of a high resistance loop, but this high resistance may have an infinitely large value, that is, an open loop. Even in this case, there is a parasitic capacitance in the buffer transistor, and due to this capacitance component, infinitely large amplification is not achieved, and detection similar to that described above is possible. In this case, the advantage is that the timing structure of the circuit becomes simple. Further, if the value of the detection resistor is small, amplification is not performed using this method. Generally, about 5 of the coil resistance
When the amplification factor is higher than 1, the amplification factor becomes 1 or more. When designing this method for detecting rotation or non-rotation of the rotor, setting the detection voltage of the detection resistor 16 and voltage detector 17 is an important point. Furthermore, since this detection circuit is used in common with magnetic field detection,
Even when used in conjunction with a step motor driven by a correction drive method, there are few factors that complicate the circuit configuration. Further, the settings of the detection resistor 16 and the detector 17 for detecting the rotation of the rotor are set to optimum values based on the inductance of the step motor, the DC resistance, the magnetic circuit, etc. However, the higher the detection sensitivity of the magnetic field detection circuit, the less it will affect the drive of the step motor, so the detection voltage can be set in two ways: low for magnetic field detection, and high for rotor circuit detection. The optimum setting can be made by setting the voltage and switching between these two voltages. Alternatively, the value of the detection resistor may be set in two ways and switched. At this time, in the case of magnetic field detection, the larger the value of the detection resistor, the better the sensitivity. Therefore, by setting the value of the detection resistor to infinity, that is, in an open loop when detecting the voltage of the coil, the value of the detection resistor can be doubled. street settings are easily possible. Furthermore, as can be seen from the explanation of the theoretical formula, in this detection method, the amplification factor can also be controlled by the ratio of the switching times of the high impedance loop and the low impedance loop, and when detecting a magnetic field, the low impedance loop By making the time longer than the high impedance loop time, magnetic field detection sensitivity can be increased. In this case, the detection resistor, detection voltage settings, etc. may be common to both detections. Furthermore, if it is desired to increase the magnetic field detection sensitivity as much as possible, the magnetic field detection sensitivity can be easily increased by combining all of the above. Further, when an alternating magnetic field is detected, the drive pulse is determined, so that there is no need to detect the rotation of the rotor thereafter. Additionally, in this case, if the rotation detection circuit is activated, the induced voltage due to rotor vibration will be disturbed by the influence of the external magnetic field, and even if the rotor is rotating, it may be determined that it is not rotating, so the detection of the external magnetic field is not performed. In this case, it is better to disable rotation detection in terms of circuit stability and current consumption. Example (3) In the correction drive method explained in Example (2), the normal drive pulse width was fixed, but in order to further reduce the power consumption of the step motor than the method in Example (2). The second method is to normally drive with the lowest pulse width that allows rotation. FIG. 17 is a graph showing the relationship between the drive pulse width of the step motor used in the electronic timepiece of this embodiment and the coil. In the case of fixed pulse drive, the drive pulse width is set at point a in order to guarantee the maximum coil Tqmax of the step motor. The method of performing correction drive as in Example (2) is based on Tqc
If the point is the coil required for calendar feeding, the length of the drive pulse is usually set to a length of a ₂ or a ₃ . The reason is that when the rotor cannot fully rotate with the normal drive pulse, a correction pulse width is added, so if the correction pulse appears too many times, the power consumption of both is added, which causes the current to increase. It is also possible that there will be an increase. However, in reality, the rotor rotates under no load even with a pulse width of a ₀ , so if the rotor can be driven with this pulse width, it is possible to further reduce current consumption. This embodiment was invented for this purpose, and its operation will be explained first.
This will be explained with reference to FIG. Normally, the drive is performed with a pulse width of a ₀ , but if the rotor cannot rotate completely with a pulse width of a ₀ due to calendar load, etc., the detection circuit determines that the rotor is not rotating and immediately applies a correction drive pulse. Drive. The pulse width at this time is generally the first
The pulse type a in Fig. 7 is used. And the driving pulse width after the next second is a ₁ which is slightly longer than a ₀
This pulse width is automatically set as a normal drive pulse, and the drive pulse is applied to the step motor. However, according to the example shown in FIG. 17, even a ₁ does not reach the calendar torque Tqc, so the rotor stops rotating and is immediately driven by the correction pulse a. Then, the normal drive pulse after another second will automatically be a ₂
In this case, the output coil is the calender torque
Since it is larger than Tqc, the step motor is thereafter driven with a pulse width of a ₂ per second. However, as it is, the pulse width of a ₂ continues even when the calendar load is removed, which is disadvantageous for reducing power consumption. Therefore, by adding a circuit that shortens the drive pulse every N seconds, the pulse width of a ₂ will continue N times. If is output continuously
The pulse width will return to a ₁ . Further a ₁
When is outputted N times in a row, it becomes a ₀ . By driving in this manner, a conventional step motor can be driven with lower power. However, as shown in FIG. 5, the shorter the normal drive pulse width, the worse the AC magnetic resistance becomes. If it is recognized that it is in a magnetic field, the correction drive circuit is prohibited, and the normal drive pulse width is set to the peak point in area 8 or the maximum magnetic resistance in area 9 shown in the graph of Figure 5. By setting the watch to a point, it is difficult to stop due to external influences, and when looking at the watch as a whole, it consumes less power, and it is not only smaller and thinner without increasing the number of mechanical parts. Also, it does not require a strong anti-magnetic structure and is advantageous in terms of cost. In the present invention, we have described the influence on alternating current magnetic fields as external magnetic fields, but in the case of direct current magnetic fields, the method described in the embodiments of the present invention does not cause malfunction in determining rotation or non-rotation. . The reason is that in the case of an AC magnetic field, a voltage is generated in the coil due to the effect of the transformer, but in the case of a DC magnetic field, no voltage is generated in the coil. Although the present invention has been explained using an integral stator type step motor, the same effect can be obtained with any type of step motor, such as a commonly used two-piece stator type step motor or a single-phase drive type step motor. It will be done. FIG. 19A shows an example in which the device of the present invention is incorporated into an actual electronic timepiece. 60 is a base plate, 61 is a coil constituting a step motor, 62 is a stator constituting the step motor, and 63 is a bearing for rollers and a gear train. 64 is a battery, 65 is a crystal oscillator, 66 is an IC
is mounted and resin molded. This is a circuit block, and the only difference in embodiments (1), (2), and (3) of the present invention is the IC. FIG. 19B is a block diagram of the entire electronic timepiece. The oscillator 90 conventionally uses a 32768 Hz crystal oscillator, and the frequency divider 91 divides the 32768 Hz signal in 15 steps to generate a 1 Hz clock reference signal. The waveform synthesis unit 95 outputs pulse widths of each length of the frequency dividing stage, which are the basis of various pulse width sequences for detection, drive, etc. The control unit 92 is configured according to embodiments (1), (2), and (3).
Depending on the presence or absence of a detection signal, different driving pulses are applied to the driving section, and the step motor 94 is driven with a pulse width that corresponds to each state. FIGS. 20A and 20B show an example of the circuit of the drive/detection section 93, which consists of the control section 92, drive circuit 93a, and detection circuit 93b shown in the block diagram FIG. 19B. P gates 21, 22 and N gates 23, 24 are 2
A set of CMOS inverters is constituted, and the output terminals a and b of each are connected to both ends of the coil 20 of the step motor, and at the same time, are connected to one ends of detection resistors 28 and 29. The other ends of the detection resistors 28 and 29 are connected to the source inputs of the N gates 25 and 26. The positive input terminals of the voltage comparators 30 and 31 are connected to one ends a and b of the detection resistors 28 and 29, the negative input terminals are connected to the voltage dividing point of the reference voltage resistor 34, and the output terminals are both connected to the OR gate 32. One end of the reference voltage resistor 34 is grounded via the N gate 27. The two input terminals of the AND gate 33 are connected to the output of the OR gate 32 and the gate terminal of the N gate 27. P and N gates 21, 22, 23, 24, 25, 26,
27 gate terminals 101, 102, 103, 10
4, 105, 106, 107 and and gate 3
The output terminal 110 of No. 3 is connected to the control section 92 . Terminals with the same numbers in FIGS. 20A and 20B are connected, respectively. A flip-flop (hereinafter abbreviated as FF) 74 is of a negative edge trigger type, and is connected from the phase control terminal 122 to a clock input CL via an inverter (hereinafter abbreviated as NOT) 73. FF74
The output Q of is an AND gate (abbreviated as AND) 7
5, AND76, the output of FF74 is AND77,
It is input to AND78. The drive terminal 121 is
It is input to AND75 and AND77. The detection signal input terminal 124 is connected to AND76 and AND78. The output of AND75 is connected to terminal 109 via NOT79, and is also connected to the NOR gate (hereinafter referred to as
(abbreviated as NOR) 81. The output of AND76 is connected to terminal 105 and NOR81. AND
The output of 77 is sent to terminals 102 and 102 via NOT80.
Connected to NOR82. The output of NOR81 is on terminal 103, and the output of NOR82 is on terminal 104.
In addition, the detection signal input terminal 124 is connected to the terminal 107. Next, the operation in FIG. 20B will be explained. The phase control terminal 122 is a force that reverses the direction of the current flowing to the step motor 94, and since it is connected to the NOT 73, the direction of the drive pulse and detection pulse to the step motor 94 is reversed with a positive edge pulse. Therefore, in the case of a normal 1-second movement clock, a 1-second pulse is input. The relationship between the input and output in Figure 20B when the output Q of FF74 is "H" (abbreviation for high level voltage) and when Q = "L" (abbreviation for low level voltage) is as shown in the following table. become.

【table】

[Table] When the output signal in Table 2 is input to the circuit in FIG. I can do it. Also, when Q = "H", terminal 121 = "H" and terminal 124 = "L", P gate 21 and N gate 24 are turned on, current flows through coil 20, and step motor 94 is turned on. Rotate. Next, terminal 121
When the terminal 124 is "L" and the terminal 124 is "H", the N gates 25 and 24 are turned on, and the detection resistor 28 is inserted into the loop, resulting in a high impedance loop. Furthermore, at this time, N gate 1
07 is ON, the reference voltage is applied to the negative inputs of the voltage comparison circuits 30 and 31, and the detection signal of rotor rotation, non-rotation, or AC magnetic field is output to the terminal 110.
is output to. FIG. 21 shows an example of the control section 92 of the above embodiment (1) and embodiment (2). 21A is output from the waveform synthesis section 95,
It shows a waveform input to the control unit 92, and its waveform synthesis is performed by a general gate circuit. P _D1 is a normal drive pulse and is 3.9 msec. P _D2 is a normal drive pulse of 3.9 msec, and is a pulse of 7.8 msec for performing correction drive when the load is larger than the output torque and the rotor is not rotating. P _D3 is a pulse width selected to provide the best anti-magnetic property when it is detected to be in an alternating magnetic field, and here, forced driving is performed at 15.6 msec. P _S1 is unnecessary in the embodiment (1), and serves as a detection pulse shown in the figure in the embodiment (2). P _S2 is a signal for specifying an interval for detecting rotation or non-rotation of the rotor. Each pulse of FIG. 21A is input to the input of FIG. 21B. Terminal 140 has P _D3 , terminal 142
is P _S2 , terminal 143 is P _D1 , terminal 144 is P _D2 ,
P _S1 is input to the terminal 145, and an output signal from the detection circuit is input to the terminal 141. Terminal 141 is connected to SR-FF15 via AND156
S input of 0, connected to AND152. Terminal 1
42 is input to AND156 via NOT157 and is connected to the input of AND152,
The output of AND152 is connected to the S input of SR-FF151. The terminal 143 is connected to the R input of the SR-FF 151 and an OR gate (hereinafter abbreviated as OR) 154. The output of SR-FF151 is AND153
The output is input to OR154, and the output is connected to OR1.
The output of 54 is input to AND/OR 155. S.R.
The output Q of the -FF 150 is connected to the AND/OR 155, and the output of the AND/OR 155 is connected to the drive pulse output terminal 146. Also, in the FF150, the terminal 145 input to AND157 is connected to the terminal 147 via AND157.
If a magnetic field is detected, FF 150 is immediately set and all detection is prohibited. In normal operation, there is no external alternating magnetic field, so
There is no output from the AC magnetic field detection circuit and SR-FF15
0 is not set. Therefore, P _D1 3.9 msec is output to terminal 146 via OR 154. Thereafter, when the rotor rotation signal is input to the terminal 141, the SR-FF 151 is set and becomes "L", so that P _D2 =7.8 msec is not output to the terminal 146. However, when the rotor is not rotating, no signal is received at terminal 141, so SR-
FF151 is not set and is at "H". Therefore, AND153, OR154, AND・
P _D2 =7.8msec to terminal 146 via OR155
is output. The next time the watch encounters an alternating magnetic field, terminal 141
Since the detection signal is input to SR-FF150 is set and Q=“H”, AND/OR
The signal of 15.6 msec at terminal 140 is sent to terminal 14 through
6 is output. Terminal 146 is connected to input terminal 121 of the drive circuit, terminal 147 is input to terminal 124 of the drive circuit, and the step motor is forcedly driven for 15.6 msec. Next, a circuit example of the embodiment (3) is shown in FIG. 22B. FIG. 22A is an example of a control section 92 designed based on a step motor having the characteristics shown in FIG. 17, and the time chart shown in FIG. waveform is output. The waveform synthesis circuit 95 is configured by appropriately combining the signal output from the frequency dividing section 91 with a gate circuit. The time chart shown in FIG. 22A will be explained. P _a0 = 2.4 msec, P _a1 = 2・9 msec, P _a2 = 3・
4 msec, P _a3 =3.9 msec, are normal drive pulses, and one of these is automatically selected depending on the load of the step motor, and this becomes the normal drive pulse P _D1 . P _D2 is a correction pulse for re-driving when there is no rotation with the normal drive pulse P _D1 , and guarantees maximum torque in 7.8 msec. P _D3 is set to a pulse width that is strongest against an external magnetic field when it is determined that the watch has encountered a magnetic field, and is set to 15.6 msec here. P _S1 is an input pulse for detection, and in the case of AC magnetic field detection, the duty is 1:3 with "L" = 0.5 msec and "H" = 1.5 msec, and when rotor rotation is detected, the duty is 0.5 msec. The ratio is 1:1. P _S2 is a pulse for indicating the time for detecting rotation or non-rotation of the rotor, and detection normally starts 9.8 msec after the application of the drive pulse P _D1 , and the pulse width is 11.7 msec. The output from the waveform synthesis section 95 described above is connected to the terminal shown in FIG. 20B. P _a0 is terminal 174, P _a1 is terminal 175, P _a2 is terminal 176, P _a3 is terminal 177, P _D2 is terminal 17
3, P _D3 is terminal 170, P _S1 is terminal 168, P _S2
are respectively connected to the terminal 172, the detection output from the detection section is input to the terminal 171, and the terminal 178 is connected to the terminal 121 of the circuit diagram of the drive section 93 in FIG. 20B.
Terminal 169 is connected to terminal 124 of FIG. 20B. Terminal 170, terminal 171, terminal 172, terminal 1
73, AND183, NOT184, AND185,
SR-FF180, SR-FF181, AND・OR1
The configurations and operations of 82, AND200, and AND201 are exactly the same as those in FIG. 21B, so their explanations will be omitted here. OR204, AND205, AND206, OR2
07, FF202, FF203 constitute a 2-bit up/down counter, and AND20
Input from 0 is up input, AND186
The input from is a down count, and the output of this counter is the output of each of FF202 and FF203.
Let Q ₀ and Q ₁ be. The output of the up/down counter is connected to a decoder 189, and the output of the decoder P
_D1 is configured as shown in the table below.

[Table] The normal drive pulse output by the decoder 189 is equivalent to the normal drive pulse explained in FIG. 21B, and is input to the OR 201 and RS-FF 181. In addition, in order to prohibit the input of the driving detection signal with the normal pulse P _D1 , it is input to the AND 209 via the NOT 208, and the output of P _S1 does not appear at the terminal 169 when the normal driving pulse is applied. Further, since the output of AND 209 is outputted to terminal 169 via AND 210, all detections are immediately inhibited as soon as an alternating magnetic field is detected. Further, P _a0 and the normal drive pulse P _D1 are input to the exclusive NOR 188, and input is prohibited when P _D1 =P _a0 , and input to the N-ary counter 187 every second when P _D1 ≠ P _a0 . N-ary counter 187
However, when it finishes counting N, the output of the N-ary counter 187 becomes "H", and the signal synchronized with P _D1 becomes OR2.
04, the up/down counter is counted down. Also, if the rotor is not rotating, AND200
Since P _D2 is output and the up/down counter counts up, the length of P _D1 is P _a0 → P _a
1 , P _a1 → P _a2 , P _a2 → P _a3 . As described above, according to the configuration of the present invention, when the present invention is applied to an electronic watch, the rotor rotation/non-rotation detection device used in the drive method for reducing current consumption and the magnetic field detection device have the same configuration, and All the elements used are conventionally used parts,
Since the circuit portions can be easily configured into integrated circuits, the only cost increase is due to chip size. However, chip size and IC costs continue to decline as technology advances, so this is not a disadvantage. On the other hand, since it uses a low power consumption driving method, the battery capacity can be lowered for the same battery life, and the battery size can be reduced. Furthermore, since it is difficult to stop even when exposed to external magnetic fields, there is no need for a strong anti-magnetic structure, and the anti-magnetic structure itself can be eliminated, allowing electronic watches to be made smaller, thinner,
It is effective in all aspects, including lower costs and higher quality.

[Brief explanation of the drawing]

Figures 1A and B...A perspective view and drive pulse waveform diagram of a conventional step motor for electronic watches, Figure 2...A plan view showing the state of the magnetic core and magnetic field, Figure 3...A current waveform diagram of the step motor, Figure 4 Figures A, B...Driving circuit and detection circuit diagram according to the present invention, Figure 5...Characteristic diagram of AC magnetic resistance and pulse width, Figure 6... Waveform diagram of conventional correction pulse type drive pulse, Figure 7...Invention 8. A time chart showing an example of the signal at each point in FIG. 7. FIG. 9... Another example of the signal at each point in FIG. 7. Figure 10: A diagram showing the correspondence between the detected voltage and the rotor rotation angle; Figure 11: A diagram showing the difference between the detected voltage and the rotor rotation angle when the rotor is rotating and when it is not rotating.
Fig. 12...Detection voltage waveform diagram according to the present invention, first
Figure 3...Symbol of N-channel transistor, Figure 14...Equivalent circuit of N-channel transistor,
FIG. 15: Equivalent circuit of the detection circuit according to the present invention,
Fig. 16A: An enlarged view of the tip of the voltage waveform shown in Fig. 12, Fig. 16B: Detected voltage waveform diagram in an alternating current magnetic field according to the present invention, Fig. 16 C: Detected voltage characteristics showing the switching effect according to the present invention Figure, No. 17
Fig. 18: Waveform diagram of the drive pulse of the corrected drive system according to the present invention, Fig. 19A: Plan view of the electronic timepiece, Fig. 19B
...Block diagram of the electronic timepiece according to the present invention, FIG. 20A...Circuit diagram of the drive detection section in FIG. 19B, FIG. 20B...Circuit showing one embodiment of the control section in FIG. 19B 21A...A time chart showing an example of the output of the waveform synthesis section in FIG. 19B, FIG. 21B...A circuit showing an example of the control section that receives the input of FIG. 21A. 22A...A time chart showing another embodiment of the output of the waveform synthesis section in FIG. 19B, FIG. 22B...Showing an embodiment of the control section that receives FIG. 22A as input. circuit diagram. 1... Stator, 2... Rotor, 3... Coil, 1
6, 29... Detection resistor, 6, 17, 30, 31... Voltage comparator, 34... Reference voltage generator, 90... Frequency dividing section, 91... Waveform synthesis section, 92... Control section, 93...
Drive/detection section, 93a... Drive circuit, 93b... Detection circuit, 94... Step motor.

Claims (1)

[Scope of Claims] 1. A step motor comprising a rotor, a stator, and a coil, a drive circuit that supplies a drive pulse having a predetermined effective power to the step motor, and a closed loop including the coil of the step motor. detects rotation or non-rotation of the rotor from a voltage value induced in the closed loop by the operation of the rotor after applying the drive pulse, and detects the presence or absence of an external magnetic field from the voltage value induced in the closed loop by an external magnetic field. a detection means for outputting each detection signal using a detection means; An electronic timepiece comprising: a control circuit that supplies a drive pulse having a larger effective power than a drive pulse to the drive circuit. 2. In claim 1, the detection means includes, in addition to a gate circuit forming a first closed loop including a drive coil, a gate circuit forming a second closed loop including a drive coil and a high impedance element in series. including electronic clocks. 3. The electronic timepiece according to claim 2, wherein the detection means is alternately switched between a first closed loop and a second closed loop.