JPS6262307B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention mainly relates to a method of driving a step motor for an electronic wristwatch. For step motors that require low power consumption, such as ultra-compact step motors for electronic wristwatches, methods of reducing power consumption include improving the electrical-to-mechanical conversion efficiency of the step motor itself, and driving it with low power during normal times. A so-called corrective drive system has been devised in which, when the rotor does not rotate normally for some reason, it is quickly re-driven with higher power than usual. When adopting this correction drive method, the important thing is how to detect rotation/non-rotation of the rotor, and how to prevent it from stopping due to external conditions such as magnetic resistance compared to the conventional fixed pulse drive method. The question is whether to secure it. A in FIG. 1 is an example of a two-pole step motor that has been used to drive the hands of conventional electronic watches and is also used in the present invention.
is an example of an inverted pulse conventionally used to drive a step motor having this structure. By applying the driving pulse B in FIG. 1 to the coil 3, the stator 1 is magnetized, and the rotor rotates 180 degrees by repulsion and attraction from the magnetic poles of the rotor 2. Conventionally, the length of the applied drive 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, and voltage drop at the end of its life.
I had to drive. Therefore, we have improved this method by driving the step motor with the last possible pulse length, which normally does not have much margin, and equipped with a detection circuit that determines whether the rotor has rotated or not with the pulse. A method has been proposed in which corrective driving is performed using a pulse signal with a large pulse width, as has been conventionally used, only when it is determined that the motor is not rotating. It is difficult to provide a special detection element such as a mechanical contact, a Hall element, etc. to detect rotation/non-rotation of the rotor due to the demands for miniaturization, thinness, and low cost of the watch. Therefore, we took into account the characteristic that the waveform and voltage value of the generated voltage due to rotor vibration after applying the drive pulse are different when the rotor is rotating and when it is not rotating.
A method is used to detect rotation or non-rotation of the rotor. However, this conventional detection of rotation/non-rotation causes erroneous detection when encountering an alternating magnetic field, so it has been necessary to strengthen the shield structure compared to the past. FIG. 2 is a circuit example of a step motor driving and detecting section used conventionally and in the present invention. This circuit configuration consists of N-channel FET gates (hereinafter abbreviated as N-gate) 4b and 5b and a p-channel FET gate.
FET gate (hereinafter abbreviated as p gate) 4a, 5a
Separate the inputs of N gates 4b, 5b, p
It is constructed so that the gates 4a and 5a are turned off at the same time, and includes detection resistors 6a and 6b for detecting rotation/non-rotation of the rotor 2 and N gates 7a and 7b for switching these resistors. FIG. 3 is a time chart in the conventional correction drive system. The voltage applied to both ends of the coil causes a current to flow in the section shown in FIG. 3a, as shown in the current path 9 shown in FIG. Next, in the section shown in FIG. 3b, the circuit is switched to a closed circuit including the detection resistor 6b like the closed circuit 10 shown in FIG. At this time, a voltage generated by the vibration of the rotor 2 after application of the drive pulse is generated at the terminal 8b. If a non-rotation signal is detected in the detection section b, current is applied to the coil 3 again in the section shown in FIG. Perform correction drive of the motor. Next, the principle of rotor rotation/non-rotation detection will be explained in detail. Figure 4 shows the current waveform when current is passed through the coil 3 of a step motor with a coil resistance of 3 kΩ and 10,000 turns. This is the current waveform when the driving pulse length a is 3.9 m sec, and during this period, the waveform is almost the same regardless of rotation or non-rotation. The section in Fig. 4b shows the rotor 2 after the drive pulse is applied.
The current waveform in this section changes greatly depending on whether the rotor 2 is rotating or not, and whether it is under no load or under load. Waveform b ₁ of section b in Figure 4
is the current waveform when rotor 2 rotates,
Waveform _b2 is a current waveform when the motor is not rotating. The drive detection circuit in Figure 2 was devised to take the difference in current due to rotation and non-rotation as a voltage waveform, and in the section b in Figure 4, the closed circuit 1
Switch the circuit to 0. By doing so, the current generated due to the vibration of the rotor 2 is transferred to the detection resistor 6b.
As a result, a larger voltage waveform appears at terminal 8b than when no detection resistor is attached. In section b, the current in the positive direction is in the opposite direction to the detection resistor 6b of the closed circuit 10 in FIG. 2, and therefore appears as a negative voltage. Further, in the OFF state, the N gate 5b has a PN junction between the drain and the P-well, and functions as a diode with Vss as the anode. Therefore, terminal 8
A voltage that is negative when viewed from b flows through the N gate 5b that acts as a diode, and has an impedance similar to that of the closed circuit 11, thereby applying braking to the rotor. Next, the relationship between the movement of the rotor 2 and the detection signal will be explained using FIG. Fig. 5 shows the relationship between the stator 1 and the rotor 2, and A in Fig. 5 represents the static state of the rotor 2. and outer peripheral notches 15a, 15b for integrating the stator.
There is. However, in the case of a two-body stator, 15a,
The stator is separated at a portion 15b. When the rotor 2 is at rest, the inner notches 16a, 1
The N and S magnetic poles come to rest at positions approximately 90 degrees from 6b. B in FIG. 5 is a diagram when a driving pulse is applied to this, and the rotor rotates in the direction of arrow 17. Since the driving pulse width is as short as 3.9 m sec, the pulse ends when the shaft has rotated almost to the inner notch. When the load is small, the rotor rotates due to the inertia of the rotor, but when the load is large, the rotor cannot rotate completely and rotates in the opposite direction as shown in FIG. 5c. Since the magnetic poles of the rotor 2 pass near the outer peripheral notches 15a and 15b, a large current is generated in the coil, but at this time the drive circuit is in the state of the closed circuit 10 shown in FIG. A negative voltage is generated at the terminal 8b, a diode forward current flows through the N gate 5b, and the rotor 2 is braked. Therefore, the rotor 2 is rapidly decelerated and the voltage generated by the vibration of the rotor 2 is small thereafter. On the other hand, when the load is small and the rotor 2 rotates, the rotor 2 rotates in the direction of the arrow 19 as shown at D in FIG. At this time, since the magnetic flux generated by the rotor 2 is perpendicular to the outer peripheral notches 15a and 15b, the induced current is initially small. Furthermore, the magnetic pole is located at the outer circumferential notch 1.
A large current is generated when it rotates to the vicinity of 5a and 15b. At this time, since a negative voltage is generated at the terminal 8b of the closed circuit 10, the rotor is braked due to the diode effect of the N gate 5b. Thereafter, the rotor rotates considerably beyond the resting position shown at A in FIG. 5, and when it returns to the resting position, a voltage is generated at the terminal 8b in FIG. 2 that can detect the rotation of the rotor 2. A voltage waveform 20 in FIG. 6A is a voltage waveform at the terminal 8b when the rotor 2 described above rotates. The section a is the drive pulse application time, which is 3.9 m sec here. The circuit at this time is the current path 9 shown in FIG. 2, and the voltage value is V _DD =15.57v. 6th
The section b in Figure A is the voltage induced by the vibration of the rotor, and is the voltage waveform at the time of the closed circuit 10 in Figure 2. The negative voltage is clipped at about -0.5v due to the diode effect of the N gate 5b, and the peak of the positive voltage is 0.4v. On the other hand, the waveform 21 is for the case of non-rotation, but the positive voltage Pitsuk is less than 0.1, and by distinguishing between these two voltages, it is possible to determine whether the rotor is rotating or not. Since the difference in voltage values between rotation and non-rotation is small in this way, by amplifying it using the method explained below,
Detection becomes easier. That is, amplification is made possible by alternately switching the closed circuit 10 and the closed circuit 11 shown in FIG. 2 in the section b shown in FIG. 6A. In the closed circuit 11 in FIG. 2, N gates 4b, 5b
Coil 3 is an element with an ON resistance of about 100Ω.
Since both ends of the rotor are shot, the current induced by rotor vibration is large. However, when switching from the closed circuit 11 to the closed circuit 10, the current momentarily flows through the detection resistor 16b due to the inductance component of the coil 3. Therefore, a momentary high peak voltage is generated across the detection resistor. The induced power waveform 20 due to the rotor 2 during rotation is generated by alternately switching the closed circuit 10 and the closed circuit 11 shown in FIG.
The voltage waveform will be as shown in Figure B. The time axis enlarged waveforms of the voltage waveforms 22 and 23 at this time are shown in FIG. 6C. The peak voltage is approximately after switching to closed circuit 10.
Delayed by 30μ sec. This is because there is a passitance component between the drain and source of the N gate 5b. With the method described above, the signal for detection can be easily amplified several times, making it easier to detect whether the rotor 2 is rotating or not. Although it is possible to detect rotation or non-rotation of the rotor 2 as explained above, this method has a major drawback. When the step motor enters an external alternating magnetic field, the external magnetic field induces a voltage in the coil 3, and it is determined that the rotor 2 is rotating even if it is not rotating. The problem is that the so-called magnetic resistance is usually determined by the pulse width of 3.9 msec that drives the step motor. Moreover, this AC magnetic resistance becomes a graph as shown in FIG. 7, and at 3.9 msec in this example, it becomes less than 3 Oersted. Therefore, when driving the step motor of the correction drive circuit, it is necessary to have a more strict anti-magnetic structure than before, and while the aim was to make it smaller, thinner, and lower in cost, the magnetic anti-magnetic structure requires more space and cost. I haven't been able to take full advantage of that advantage. Furthermore, in order to reduce the current of the step motor, there is a drive method in which the pulse width is usually changed depending on the weight of the load. In this case, if the load is light as in the case of non-calendar feed, the rotor of the step motor will move with the minimum pulse width that allows rotation. At this time as well, as can be seen from FIG. 7, the AC magnetic resistance further deteriorates. Therefore, at this time, it is necessary to further strengthen the anti-magnetic structure such as a shield plate. Therefore, there was a drawback in that it became difficult to achieve the original purpose of reducing the current of the step motor in order to make the device thinner and smaller. The present invention has been made to eliminate the above-mentioned drawbacks, and not only makes full use of the advantages of the correction drive method, but also prevents deterioration of AC magnetic resistance.
The aim was to improve magnetic resistance even better than the conventional fixed pulse drive type step motor, and for that purpose, all ICs were used without increasing the number of parts.
This was achieved by the internal circuit. The time chart in Figure 8 is based on terminal 8b in Figure 2.
-8a, where a is the normal drive pulse, b is the rotor rotation/non-rotation detection period, c is the correction pulse when the rotor is not rotating, and b' is the rotor drive period at that time. , d is the rotor resting time, and the voltage induced in the coil 3 is detected during this rotor resting time d, and if the voltage is detected in the section d, this step motor is considered to have entered the alternating current magnetic field. The above object is achieved by driving the next driving pulse with a pulse width that has good AC magnetic resistance. The detection circuit section, which is a characteristic part of the present invention, uses a high impedance element to convert the detection signal into a voltage, making it easier to detect the detection signal. This high impedance element can be easily formed by using a diffused resistor inside the IC.
All circuits can be configured on an IC. In this case, diffusion layers such as P ^- , P ⁺ , N ^-, etc. are used as the diffusion resistance. Furthermore, all of the important elements for the configuration of the present invention, such as the voltage comparator, can be configured with elements that can be easily incorporated into an IC. Next, the content of the present invention will be explained in detail according to examples. FIG. 9 shows an electronic timepiece according to the present invention, in which 60 is a main plate, 61 is a coil block, 62 is a stator, 63 is a support for a rotor, gear train, etc., 64 is a battery, and 65 is a crystal oscillator. , 66 is a circuit block mounting an IC in which this circuit is built. FIG. 10 is a block diagram of an electronic circuit of an electronic timepiece implemented in the present invention. Reference numeral 90 is an oscillation section, which uses a 32768 Hz crystal resonator.
This signal is frequency-divided by a flip-flop in a frequency divider 91 to a 1-second signal, and the output of each stage of the flip-flop is sent to a waveform synthesizer 95.
Then, step motor drive pulses, timings and pulses necessary for detection are synthesized using AND gates, OR gates, flip-flops, etc. The driving and detecting section 93 includes the circuit shown in FIG. 2 and further 8a, 8b.
It is composed of a binary judgment logic element that judges the detection signal outputted to the detection signal. Further, the step motor drive output is connected to the step motor 94, and the detection signal is fed back to the control section 92. Oscillation section 90 is a 32768Hz crystal oscillation, frequency division section 91
consists of 15 stages of flip-flops and divides the frequency up to a 1 second period signal. The waveform synthesis section 95 synthesizes signals necessary for the control section 92 using the signals from the frequency division section. Drive and detection section 93
is common to Examples (1) and (2) shown later, so it will be explained first. FIG. 11A shows a part of the drive circuit in the drive and detection section. Output terminals 101, 102, 10 in Fig. 11A
3, 104, 105, and 106 are connected to the same numbered terminals of the input terminals in Figure 2, respectively, and terminal 1
07 is connected to the terminal 107 in FIG. 11B. The input terminal 147 in FIG. 11A is “H” (High
The terminal 122 is a terminal that changes the state of a flip-flop (hereinafter abbreviated as FF) 74 that controls the direction of the current flowing to the step motor.
The PD ₃ signals of FIGS. 12A and 15A are input, and the state is changed by positive edge input. The terminal 146 is connected to the second
The current path 9 is shown in the figure. Next, the circuit shown in FIG. 11A will be explained in detail. The flip-flop (hereinafter abbreviated as FF) 74 is
It is a negative edge trigger type and has a phase control terminal 122.
is connected to the clock input CL via an inverter (hereinafter abbreviated as NOT) 73. The output Q of FF74 is an AND gate (abbreviated as AND) 75,
AND (76, the output of FF74 is AND77,
It is input to AND78. The drive terminal 146 is
Connected to AND75 and AND77. The detection signal input terminal 147 is connected to AND76 and AND78. The output of AND75 is connected to terminal 101 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 connected to terminal 102, NOR via NOT80.
82. The output of NOR 81 is connected to terminal 103, the output of NOR 82 is connected to terminal 104, and the detection signal input terminal 147 is connected to terminal 107. In FIG. 11, B is a voltage detection section that constitutes a part of the detection section of the drive/detection section 93. In FIG. Terminals 8a and 8b in FIG. 2 are connected to respective terminals in FIG. 11B. Terminal 107 in FIG. 11A is also connected to terminal 107 in FIG. 11B. Resistors 85 and 86 divide the power supply voltage V _DD and serve as a reference voltage for detecting rotor rotation/non-rotation and external magnetic field detection. Prevent from flowing. 83 and 84 are binary comparison logic elements, so-called comparators, and when the voltage of the positive input is higher than that of the negative input, the output becomes "H" level.
The outputs of comparators 83 and 84 are input to OR88, and the output is output from AND89 along with the signal at terminal 107.
The detection output is output to the terminal 110. Embodiment (1) A in FIG. 12 is the waveform synthesis unit 95 shown in FIG.
This is the output waveform of the control section 9 shown in B in FIG.
2 input terminals P _D1 , P _D2 , P _D3 , P _S1 , and P _S2 , respectively. The waveform synthesis circuit of A in FIG. 12 synthesizes signals from the frequency dividing section using AND, OR, NOR, NAND, NOT gates, etc. Here, P _D1 is a normal drive pulse of 3.9 m for 1 second.
It is a pulse of sec. P _D2 is 7.8m with correction pulse
sec. P _D3 is a 15.6 m sec pulse with good magnetic resistance that is output when an alternating magnetic field is detected. P _S1 is a pulse for AC magnetic field detection and circuit detection signal amplification, and from 23.4 m sec before the positive 1 second to the positive 1 second, "H" = 0.5 m sec, "L" = 1.5 m sec.
sec, which is a pulse of 1:3,
1 second later, 3.9m sec “L” continues, then “H” =
0.5 m sec, "L" = 0.5 m sec, that is, a pulse with a ratio of 1:1. This ratio of 1:
The rotor rotation detection signal is amplified using the pulse 1, but the actual rotor rotation is detected by P _S2 .
This is only during the period of 11.7 msec when the signal is "H". Next, B in FIG. 12 will be explained. The signal of the detection output 110 is input to the terminal 141 . The signal is passed through AND156 to SR-FF1
50 and is input to AND152.
The terminal 142 is input to the AND 156 via the NOT 157 and is connected to the input of the AND 152, and the output of the AND 152 is connected to the input of the SR-FF 151. Terminal 143 is the R input of SR-FF151
Connected to OR154. The output of SR-FF151 is connected to AND153, the output of AND153 is input to OR154, and the output of OR154 is
Input to AND/OR155. SR-FF150
The output Q, is connected to AND/OR155.
The output of the AND/OR 155 is connected to the drive pulse output terminal 146. Also, the output of FF150 is
It is input to AND157. Terminal 145 is connected to terminal 147 via AND157. During normal operation, there is no external AC magnetic field, so there is no output from the AC magnetic field detection circuit, and the SR
-FF150 is not set. Therefore RO154
P _D1 3.9 m sec is output to terminal 146 via. After that, when the rotor rotation signal is input to the terminal 141, SR-FF151 is set and FF1
51 = “L”, so P _D2 = 7.8 m sec
is not output to terminal 146. However, when the rotor is not rotating, no signal is received at terminal 141, so SR-FF151 is not set.
It is marked “H”. Therefore, AND153, OR
P _D2 =7.8 m sec is output to the terminal 146 via AND/OR 154 and 155. The next time the watch encounters an alternating magnetic field, terminal 141
Since the detection signal is input to the terminal 140, the SR-FF 150 is set, Q="H", and the signal 15.6 msec from the terminal 140 is output to the terminal 146 via AND/OR. The signal at the terminal 146 is the input terminal 146 of the drive circuit.
The signal at terminal 147 is input to terminal 1 of the drive circuit.
Since the input is to P47, the step motor is
Forced driving is performed for _D3 = 15.6 m sec. Example (2) In the correction drive method described in Example (1), the normal drive pulse width was fixed. In the embodiment (2), in order to further reduce the power consumption of the step motor than in the method of the embodiment (1), the step motor is driven with the lowest pulse width that allows the normal drive pulse width to rotate. FIG. 13 is a graph showing the relationship between the drive pulse width and torque of the step motor used in the electronic timepiece of this embodiment. In the case of fixed pulse drive, the drive pulse width is set at point a in order to guarantee the maximum torque Tqmax of the step motor. In the method of performing correction drive as in Example (1), if the point Tqc is the torque required for calendar feed, the length of the normal drive pulse is a ₂ = 3.4 m sec or a ₃ = 3.9 m.
The length is set to sec. The reason is that when the rotor cannot fully rotate with the normal drive pulses, more correction pulses are added, so if the correction pulses appear too many times, the current consumption of both is added, and the current increases instead. This is because there may be cases where this happens. However, in reality, a ₀ =
Even with a pulse width of 2.4 m sec, the rotor rotates when there is no load, so if it can be driven with this pulse width, it is possible to further reduce current consumption. This embodiment was made for this purpose, and its operation is described in the 14th
This will be explained using figures. Normally, the step motor is driven with a pulse width of a ₀ = 2.4 m sec, and if the rotor cannot rotate completely with the pulse width of a ₀ due to calendar load, etc., the detection circuit determines that the rotor is not rotating. , immediately drive with a correction drive pulse. The pulse width of this correction drive is generally 7.8 msec. The driving pulse width after the next second is a ₁ = slightly longer than a ₀ = 2.4 m sec.
A pulse width of 2.9 msec 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. 13, the calendar torque Tqc is not reached even when a ₁ =2.9 m sec, so the rotor stops rotating again and is immediately driven by the correction pulse a = 7.8 m sec. Then, the normal drive pulse after another second will automatically be a ₂ = 3.4m.
It becomes sec. In this case, the output torque is larger than the calendar torque Tqc, so a ₂ = 3.4 m sec per second from then on.
The step motor is driven with a pulse width of However, if this continues, the pulse width of a ₂ =3.4 m sec will continue even when the calendar load is removed, which is disadvantageous for reducing power consumption. Therefore, by adding a circuit that shortens the drive pulse when detected after continuing to rotate for N seconds, it is possible to return to the pulse width of a ₁ = 2.9 m sec after N times of continuous output of a ₂ = 3.4 m sec. Become. Furthermore, when a ₁ is output N times in succession, it becomes a ₀ . By driving in this manner, a conventional step motor can be driven with lower power. FIG. 15 shows an example of a control section 92 designed based on a step motor having the characteristics shown in FIG. Waveform synthesis circuits 95 to 15 shown in FIG.
The waveform of the time chart shown in Figure A 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. 15A will be explained. P _a0 = 2.4 m sec, P _a1 = 2.9 m sec, P _a2 =
3.4 m sec, p _a3 = 3.9 m sec is the normal drive pulse, one of which is automatically selected according to the load of the step motor, and this is the normal drive pulse P.
It becomes _D1 . P _D2 is a correction pulse for re-driving when it is not rotating with the normal drive pulse P _D1 , and is 7.8 m.
Guarantees maximum torque in sec. P _D3 is set to the pulse width that is strongest against the external magnetic field when it is determined that the watch has encountered a magnetic field, and is set to 15.6 m sec here. P _S1 is an input pulse for detection. For AC magnetic field detection, “L” = 0.5m sec, “H” = 1.5m
sec, that is, the duty is 1:3, and when the rotor rotation is detected, the duty is 1:1 at 0.5m sec.
It is becoming. P _S2 is a pulse for specifying the time for detecting rotation/non-rotation of the rotor. Detection starts 9.8 m sec after the application of the normal drive pulse P _D1 , and the pulse width is 11.7 m sec. Each output from the waveform synthesis section 95 described above is connected to each terminal in FIG. 15B. P _a0 is terminal 174, P _a1 is terminal 175, P _a2 is terminal 176, P _a3 is terminal 177, P _D2 is terminal 1
73, P _D3 is terminal 170, P _S1 is terminal 168, P
_S2 are connected to terminals 172, respectively. terminal 17
1 is a terminal 178 to which the detection output from the detection section is input.
is a circuit diagram of the drive unit 93, and the terminal 121 in FIG.
Terminal 169 is connected to terminal 124 of FIG. 11A. Terminal 170, terminal 171, terminal 172, terminal 1
73, terminal 146, terminal 147, AND183,
NOT184, AND185, SR-FF180, SR
-FF181, AND・OR182, AND200,
The configuration and operation of the AND 201 are exactly the same as those shown in FIG. 12B, so a description thereof will be omitted here. OR204, AND205, AND206, OR2
07, FF202, and FF203 constitute a 2-bit up/down counter, and AND20
Input from 0 is up input, AND186
The input from is a down count input. The counter outputs are outputs Q ₀ and Q ₁ of FF 202 and FF 203, respectively. The output of the up-down counter is connected to a decoder 189.
The output P _D1 of the decoder is connected to Table 1.

[Table] Normal drive pulse P output by decoder 189
_D1 is the normal drive pulse P explained in FIG. 12B.
It is equivalent to _D1 and is input to OR201 and RS-FF181. Also, in order to prohibit the input of the driving detection signal with the normal driving pulse P _D1 , it is
It is input to AND209. Therefore, the output of P _S1 does not appear at the terminal 169 when the driving pulse is normally applied. Further, since the input of AND210 is connected to the output of FF180, when a magnetic field is detected, the output of AND210 becomes "L". P _a0 =
2.4 m sec and the normal drive pulse P _D1 are input to the exclusive NOR 188. For this reason P _D1
When = P _a0 , input to the N-ary counter 187 is prohibited, and when P _D1 ≠ P _a1, input to the N-ary counter 187 is prohibited.
counts every second. When the N-ary counter 187 finishes counting N, the output of the N-ary counter 187 becomes "H" and a signal synchronized with P _D1 is input to the OR 204. Therefore, the up/down counter is counted down. If the rotor is not rotating
P _D2 is output to AND200, and the up/down counter counts up. Therefore, the length of P _D1 changes as follows: P _a0 →P _a1 , P _a1 →P _a2 , P _a2 →P _a3 . In the embodiments described above, switching of the closed circuit after application of the drive pulse is performed both for amplifying the detection signal of rotation/non-rotation of the rotor 2 and for amplifying the voltage generated in the coil due to the external magnetic field. Therefore, AC magnetic field detection must already be performed in the AC magnetic field at the anti-magnetic level in the normal drive pulse P _D1 . For this reason, it is necessary to increase the detection sensitivity of external alternating magnetic fields as much as possible. In the present invention, detection of rotation/non-rotation of the rotor and detection of an external alternating magnetic field include a detection section composed of a high impedance element, a voltage comparator, and a reference voltage section. Here, the high impedance element is used to convert the current generated in the coil due to rotational vibration of the rotor and external alternating magnetic field into voltage at a certain magnification. In addition, since this high impedance element is built into the IC, it is composed of a diffused resistor or a resistor when the transistor is turned on. In this case, the resistance is formed by diffusion layers such as P ⁺ , P ^- , and N ⁺ . Also, the transistor
When ON resistors are used, 7a and 7b are used as high impedance elements in the circuit shown in FIG. 2, and in this case, 6a and 6b used as detection resistors become unnecessary. In the present invention, the sensitivity of rotation detection and the sensitivity of magnetic field detection are determined by setting the value of this high impedance element and the reference voltage. Figure 16 shows the detection resistance value R _S and the peak voltage value V _RS generated across the resistance when a diffused resistor is used as this high impedance element and this value is R _S in Example (1). FIG. The step motor used here has a coil DC resistance of 3 kΩ, 10,000 turns, and a rotor made of summarium cobalt with a diameter of 1.3 mm. The reference voltage V TH 300 in FIG. 16 is equal to the reference voltage V _TH 300 in FIG.
The voltage V _TH is set by dividing the power supply voltage V _DD by the resistors 85 and 86, and is the reference voltage for determining whether the rotor is rotating or non-rotating and determining the presence or absence of an external alternating magnetic field. Curve 301 is the maximum positive voltage that occurs within the detection section when the rotor is not rotating with the drive pulse P _D1 , and occurs at both ends of the voltage when the detection resistor R _S is changed. It represents the change in voltage _VRS . Curve 302 is a curve representing the minimum value of the maximum voltage within the detection section when the rotor rotates with the drive pulse P _D1 , and the peak voltage in the detection section when the rotor rotates always generates a voltage higher than this curve. . accordingly
Due to the tolerance limit of the detection resistor R _S built in the IC, rotation detection is possible if the reference voltage including the tolerance enters the portion sandwiched between 301 and 302. Furthermore, curve 303 is 50Hz, 3 as an external alternating magnetic field.
It represents the detection resistor R _S and the voltage generated across it in the Oersted magnetic field. It is difficult to lower the detection resistance R _S due to the relationship between these two detections and the tolerance range when the detection resistance R _S is built into an IC. Therefore, by setting a resistance that is generally 5 times or more than the coil resistance (in the example, the coil resistance is 3KΩ, so 15KΩ or more), a sufficient tolerance range can be obtained for the built-in IC. In this example, R _s = 100KΩ, with a tolerance of −
Values of 50% and +100% are sufficient. FIG. 17 shows an example of the configuration of a voltage comparator, which is an important component of the detection section. In the present invention, the performance required of the voltage comparator is: (1) There should be little comparison error with the reference voltage. (2) Things that can be easily done with C-MOS-IC components. (3) Fast response. (4) Low current consumption. The voltage comparator shown in FIG. 17 is suitable for these purposes. FIG. 17A is a detailed circuit diagram, and FIG. 17B is a block diagram. Terminal 164 is a "+" input terminal, terminal 165 is a "-" input terminal, and terminal 166 is an output terminal. The functions are summarized in Table 2.

[Table] 167 is the power supply terminal, PMOSFET16
0,162 source electrodes, respectively. The gate and drain electrodes of the PMOSFET 160 are connected, and the connection point thereof is connected to the gate of the PMOSFET 162 and the drain of the NMOSFET 161, respectively. The gate of NMOSFET161 is
is connected to terminal 164, and its source is
Connected to the drain of NMOSFET124. The drain of PMOSFET162 is NMOSFET1
63 and the output terminal 166. The gate of NMOSFET 163 is connected to terminal 165, and its source, together with the source of NMOSFET 161, is grounded to V _SS potential. Also
NMOSFET161, 163, PMOSFET16
0,162 characteristics are each equal. The operation of the voltage comparator configured as above will be explained. When input voltage V ₁ is applied to terminal 164, the potential and current at connection point 168 become as shown in FIG. 17C. In FIG. 17C, V168 is the potential of the terminal 168, and I168 is the current flowing through the terminal 168. The gate of PMOSFET162 has the above V16
8 is applied, the saturation current is as shown in Fig. 17D.
It is equal to I168 shown in the characteristics of 162. Next, when the voltage applied to the terminal 165 is _V2 , when _V2 > _V1 , the saturation current of the NMOSFET 163 becomes larger than I168. Therefore, as shown by operating point X in FIG. 17D, the potential V16 of the output terminal 166
6 is close to the "L" level. On the other hand, when V ₂ <V ₁ , the output becomes "H" level, which is shown by Y in D in FIG. 17. Therefore, the functions are summarized as shown in Table 2 above. Furthermore, in the present invention, the detection of the alternating current magnetic field and the detection of rotor rotation/non-rotation are constructed using only elements that can be easily incorporated into an IC, except for the step motor.
In particular, the impedance element used as a detection element is an IC.
It may be configured with a resistance element using a diffused resistance that can be easily built into the circuit, the ON resistance of a transistor can also be used as a switching transistor, or it can be used as a capacitor with even higher impedance and infinite resistance. be. It may also be in an open state. These elements can be easily incorporated into an IC, and in the present invention, the tolerance of their values can be set quite widely. Therefore, even if the detection circuit according to the present invention is configured in a conventional IC,
It does not become a factor that deteriorates the IC manufacturing yield. By driving the conventionally used step motor with the driving method of the present invention,
There is no cost increase factor, and the same output torque can be obtained with about half the current consumption of the conventional method, and the AC magnetic resistance is improved, making it resistant to the external environment. Therefore, when designing a watch with the same magnetic resistance and battery life as conventional ones, the magnetic shield structure can be simplified and the battery capacity can be reduced.
This makes it possible to make watches smaller and thinner, and the effects are very large.

[Brief explanation of the drawing]

FIG. 1A is a perspective view of a step motor for an electronic timepiece used conventionally and in the present invention. B in FIG. 1 is a conventional step motor drive pulse waveform diagram.
FIG. 2 is a part of a drive and detection circuit diagram of a step motor according to the prior art and the present invention. FIG. 3 is a step motor drive pulse waveform diagram of a conventional correction drive method. Figure 4 shows the current waveform of the step motor and the current waveform induced by rotor vibration when the rotor is rotating and not rotating. A in FIG. 5 is a diagram showing the relationship between the stator and rotor when the rotor is stationary. B in Figure 5
FIG. 2 is a diagram showing the rotation direction of the rotor when driving pulses are applied. FIG. 5C is a diagram showing the movement of the rotor when the rotor cannot rotate. D of FIG. 5 is a diagram showing the movement of the rotor after application of a drive pulse when the rotor rotates. FIG. 6A shows the voltage induced in the detection resistor when the rotor is rotating and not rotating. FIG. 6B shows the voltage waveform induced in the detection resistor when the rotor is rotating and not rotating and switching between a closed circuit containing high resistance and a closed circuit containing low resistance. Figure 6C is Figure B22
and 23 waveform enlarged diagrams. Figure 7 is a characteristic diagram of pulse width and AC magnetic resistance. FIG. 8 is a drive pulse waveform diagram of the correction drive and magnetic field detection method according to the present invention. FIG. 9 is a plan view of the electronic watch. FIG. 10 is a block diagram of an electronic timepiece according to the present invention. FIG. 11A shows the driving,
A circuit diagram of a portion of the detection section. FIG. 11B shows the drive,
FIG. 3 is a circuit diagram of a binary decision logic element portion of the detection section. 12th
A in the figure is a time chart showing an example of the output of the waveform synthesis section. B in FIG. 12 is a circuit diagram showing an embodiment of a control section that receives the signal of A. FIG. 13 is a characteristic diagram showing the relationship between drive pulse width and minute hand torque. FIG. 14 is a drive pulse waveform diagram showing the relationship between the correction drive method in which the drive pulse width changes according to load fluctuations and AC magnetic field detection according to the present invention. 15th
A is a time chart showing another example of the output of the waveform synthesis section. FIG. 15B is a circuit diagram showing another embodiment of the control section which receives the signal A as an input. Figure 16 shows
A diagram showing the relationship between the detection voltage V _RS and the detection resistance R _S. A in FIG. 17 is a circuit configuration diagram of a voltage comparator. 17th B
is a symbol diagram of a voltage comparator. C in Figure 17 is
Current and voltage characteristic diagrams of CMOSFET160 and 161. D in Figure 17 is CMOSFET 163, 16
2 current and voltage characteristic diagram. 1... Stator, 2... Rotor, 3... Coil, 6
a, 6b...detection resistor, 4a, 4b, 7a, 7b...
N channel FET gate, 4b, 5b...P channel gate, 9...Current path for drive pulse, 10
...Closed circuit including high resistance, 11...Closed circuit including low resistance, 83, 84... Binary judgment logic element (comparator), 85, 86... Reference voltage setting resistor.

Claims (1)

[Scope of Claims] 1. A step motor composed of a stator, a rotor, and a drive coil, a reference signal generation section, and a waveform synthesis section that synthesizes and outputs a plurality of signals including drive pulses based on the output of the reference signal generation section. , a drive unit having a plurality of switching elements connected to the drive coil for supplying drive pulses having a predetermined effective power to the step motor, and a diffusion resistance of an integrated circuit or a resistance when the switching elements are turned on. an impedance element connected to the drive coil in parallel with a switching element of the drive unit; and a voltage generated in the impedance element during a period other than when a drive pulse is applied to the step motor and the drive coil is connected to a power supply voltage. a detection unit having a voltage comparator that outputs a detection signal that compares the value with a predetermined reference voltage and detects the presence or absence of an external magnetic field, or the rotation/non-rotation of the rotor and the presence or absence of an external magnetic field; and the waveform synthesis unit. 1. A detecting device for an electronic timepiece, comprising: a control section that inputs a signal from the waveform synthesizing section and selects a signal from the waveform synthesizing section based on the output of the detection, and outputs the selected signal to the driving section. 2. The detection device for an electronic timepiece according to claim 1, wherein the impedance element has a resistance value that is five times or more the resistance value of the drive coil.