JPS6115384B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a low power consumption drive system for a step motor of an analog display type electronic timepiece. Conventionally, the display mechanism of a commonly used analog display type quartz watch is constructed as shown in FIG. The output of the motor composed of the stator 1, coil 7, and rotor 6 is
The signal is transmitted to the wheel trains 2, 3, 4, and 5, and further drives display mechanisms such as a second hand, a minute hand, an hour hand, and in some cases a calendar via several wheel trains (not shown). Next, FIG. 2 shows an example of the circuit configuration of a conventionally used electronic wristwatch. The oscillation signal of the oscillation circuit 10 is sequentially frequency-divided by the frequency divider circuit 11. These frequency-divided signals are converted by the pulse synthesis circuit 12 into two signals with a pulse width of 7.8 msec, a period of 2 seconds, and a phase difference of 1 second.
As a result of being applied to the inputs 15 and 16 of 3a and 13b, a reversal pulse is applied to the coil 7 in which the direction of current flow changes every second, and the rotor 6, which is magnetized to two poles, sequentially rotates by 180 degrees. do. An example of the coil current waveform at this time is shown in FIG. By the way, the driving pulse width (7.8 m sec in the above example), coil resistance, number of coil turns, dimensions of each part of the step motor, etc. of the conventional electronic wristwatch are based on all the situations that the electronic wristwatch is expected to encounter, such as a calendar, etc. If the train load becomes heavy,
It is designed to be able to drive the step motor stably even when the battery is placed in a magnetic field, when the internal resistance of the battery becomes extremely high at low temperatures, or when the battery voltage drops at the end of its life. As a result, power was wasted even though large output torque was not required under normal conditions, which became a major obstacle in reducing the overall power consumption of watches. The present invention was proposed in order to eliminate the above-mentioned drawbacks of the prior art, and it supplies the step motor with pulses of the minimum pulse width commensurate with the current load condition of the step motor. This aims to reduce the Hereinafter, before explaining the present invention in detail, an example of the operation according to the present invention will be briefly explained using FIGS. 4a, b, and c. The drive pulse for the step motor used in the electronic timepiece of the present invention is composed of two types of pulses: a normal drive pulse and a corrected drive pulse. The order of pulses supplied to the step motor is the normal drive pulse and the correction drive pulse, but the correction drive pulse is, in principle, supplied when the step motor cannot rotate with the normal drive pulse. Then, when the corrected drive pulse is supplied to the step motor, since it was not possible to rotate with the normal drive pulse, the pulse width of the next normal drive pulse is lengthened by a predetermined amount to make it easier to rotate. On the other hand, if the step motor can be rotated several steps with only the normal drive pulse, the pulse width of the normal drive pulse is shortened by a predetermined amount. Through the above operations, the pulse width of the normal drive pulse _P1 becomes almost the minimum pulse width that can drive the step motor in the current state, and therefore,
Power consumption is almost minimal. For example, Figure 4a
The P ₁ pulse width, which was currently 3.9 m sec, can be expressed as
The time is shortened to 3.4 msec by the operation described in item 2 above. Assume that the step motor can further rotate in this state. Next, after several steps of rotation at 3.4 m sec, the pulse width of _P1 is set to 2.9 m sec by the above-described operation again. Assuming that the step motor cannot rotate in this state, the non-rotation of the rotor is detected by the operation described in item 1 above, and the correction drive pulse P ₂ is immediately applied, and the step motor P ₁ from the next step onwards is detected. Set the pulse width to 3.4m sec. Thereafter, the normal drive pulse width of 3.4 msec is maintained while repeating the above operation. If for some reason the step motor is unable to rotate with the normal drive pulse width of 3.4 msec,
As shown in Fig. 4b, non-rotation of the rotor is detected by rotor motion detection, and the corrective drive is immediately performed.
The normal drive pulse width after the next step is 3.9m sec.
is set to After that, if there is room for rotation again, take several steps as shown in Figure 4c.
After normal driving for 3.4 m sec, the normal drive pulse width is set to 3.4 m sec by the operation described in the second term above. Furthermore, when a reuse operation is performed to adjust the time of this electronic watch, and when the timekeeping is restarted after the timekeeping has stopped, the drive pulse width is usually the minimum pulse width among the available pulse widths. (for example, 2.4m sec), and after that,
Continue the above action. The outline of the operation of the present invention has been described above, and next, the principle of rotor operation detection, which is an important element of the present invention, will be explained. Possible methods for detecting rotor motion include using a mechanical switch or an external element such as a Hall element, but it is difficult to install these mechanisms in an extremely small volume such as an electronic wristwatch. be. Two different motion detection principles will be explained below as an example of rotor motion detection in which a detection circuit can be realized in a single integrated circuit along with oscillation, frequency division, drive circuits, etc. without requiring external elements. The first method utilizes the fact that when an integral stator is used, the drive current waveform differs depending on the position of the rotor. Fig. 5 shows an integrated stator connected by a saturable magnetic path 17 that is made to be easily saturated.Although not clearly shown in the figure, the stator is magnetically engaged with a magnetic core around which a coil 7 is wound. There is. Also,
This stator is provided with a notch 18 for determining the direction of rotation of the rotor 6, which is magnetized into two poles in the radial direction. Figure 5 shows the state immediately after a current is applied to the coil 7, and when no current is applied to the coil 7, the rotor 6 is rotated so that the angle between the notch 18 and the rotor magnetic pole is approximately 90 degrees. stationary in position. In this state, when a current is passed through the coil 7 in the direction of the arrow, magnetic poles are formed in the stator 1 as shown in FIG. 5, and the rotor 6 is repelled and rotates clockwise. When the current flowing through the coil 7 is cut off, the rotor 6
comes to rest with the magnetic poles reversed from those shown in Figure 5.
Thereafter, by applying current to the coil 7 in the opposite direction, the rotor 6 sequentially continues to rotate clockwise. In a step motor constructed of an integrated stator having the saturable portion 17 as described above, the current waveform when current is passed through the coil 7 has a gentle rising portion as shown in FIG. This is because the magnetic resistance of the magnetic circuit seen from the coil 7 is extremely low until the saturable part 17 of the stator 1 is saturated, resulting in a low resistance R and a large time constant γ of the coil series circuit. be. This can be expressed as a formula as follows. γ=L/R L≒N ₂ /Rm From now on, γ=N ₂ /(R×Rm) where, L: inductance of coil 7, N:
The number of turns of the coil 7, Rm: magnetic resistance. When the saturable part 17 of the stator 1 is saturated, the magnetic permeability of the saturated part is the same as that of air, so Rm
increases, the time constant γ of the circuit decreases, and the current waveform suddenly rises as shown in FIG. Furthermore, since this saturation time is also affected by the magnetization state of the motor, the higher the current level at the time of pulse interruption, the longer the saturation time becomes. Therefore, since the saturation time becomes longer after the correction drive pulse is supplied to the step 7, it is preferable to supply the step motor with a degaussing pulse to cancel this effect. The operation of the rotor in this example is detected as a difference in the time constant of the resistor-coil series circuit described above after driving with normal pulses. Next, the reason for the difference in time constant will be explained using drawings. FIG. 6 shows the state of the magnetic field when current begins to flow through the coil 7, and the rotor 6 has magnetic poles at rotatable positions. The magnetic flux lines 20 show the state of the magnetic flux generated from the rotor 6, and in reality, there is also magnetic flux that interlinks with the coil 7.
It has been omitted here. The magnetic flux lines 20a and 20b are oriented in the direction of the arrow in FIG. 6 in the saturable parts 17a, 17b of the stator 1. The saturable portion 17 is often not yet saturated. In this state, current is applied to the coil 7 as shown by the arrow in order to rotate the rotor 6 clockwise. Magnetic flux 19 generated by coil 7
a, 19b are saturable parts 17a, 1 of the stator 1
Magnetic flux 20a, 20b generated from the rotor 6 at 7b
, and therefore the saturable portion 17 of the stator 1 is quickly saturated. After this, rotor 6
Although sufficient magnetic flux is generated to rotate the rotor 6, it is omitted in FIG. FIG. 8 22 shows the waveform of the current flowing through the coil at this time. On the other hand, FIG. 7 shows the state of the magnetic flux when current is applied to the coil 7 where the rotor 6 cannot rotate for some reason and has returned to its original position. Originally, in order to rotate the rotor 6, a current must flow through the coil 7 in the opposite direction to the arrow, that is, in the same direction as shown in Figure 6, but the current flows through the coil 7 every time. Since a reversal current that changes the direction of the rotor 6 is applied, such a state occurs when the rotor 6 cannot rotate. Since the rotor 6 could not rotate,
The direction of the magnetic flux generated from the rotor 6 is the same as in FIG. Since current flows in the coil 7 in the opposite direction to that shown in Fig. 6, the magnetic flux directions are 21a and 21b.
become that way. Saturable portion 17a, 1 of stator 1
7b, the magnetic fluxes generated by the rotor 6 and the coil 7 cancel each other out, and the stator 1
It takes longer time to saturate the saturable part of. This state is shown in Figure 8, 23.
It is. An example of rotor position detection means that utilizes the above phenomenon is shown in FIGS. 9 and 10. FIG. 9 shows a conventional drive circuit, that is, MOS gates 24, 25, 26, which constitute a drive inverter.
27, detection gates 28, 29, detection resistor 30,
Capacitor-charging transmission gate 3
1. This is a rotor position detection circuit constructed by adding a capacitor 33 and a voltage comparator 32. First of all,
To give an example of normal drive timing, current is passed through the path 34 to excite the coil 7 and drive the rotor. After the rotor movement is almost completed, a short period of time (approximately 0.5 m sec to 1 m sec) is applied to path 35.
A first detection pulse is applied to coil 7 and then a second detection pulse is applied to coil 7, this time in path 36. Now, if the rotor rotates normally one step by the normal drive pulse, the relationship between the rotor magnetic poles and the stator magnetic poles when the first detection pulse is applied to the coil is as shown in Figure 6. Then, the rotor can be driven one step again. The rising part of the current waveform at this time is shown in Fig. 822.
It shows a waveform with a fast rise like this. Next, when the second detection pulse is applied, the rotor position is the same as that of the first detection pulse (the pulse width of the detection pulse is short and the high resistance 30 is connected in series with the coil 7). , the rotor does not rotate due to the detection pulse.) Since the direction of excitation is opposite, the relationship between the rotor magnetic poles and the stator magnetic poles is as shown in Figure 7, and the rising part of the current waveform is as shown in Figure 8, 23. The waveform has a slow rise. However, since the detection resistor 30 is connected in series with the coil when the detection pulse is applied, strictly speaking, the waveform does not match the waveform shown in FIG. 8, but the characteristics of the rising portion remain the same. Therefore, the detection resistor 30
When observing the terminal potential of
The potential Vs ₁ due to the detection pulse rises to a higher potential than the potential Vs ₂ due to the second detection pulse. Next, if the rotor cannot rotate one step by the normal drive pulse and returns to the initial position, the relationship between the rotor magnetic poles and the stator magnetic poles when the first detection pulse and the second detection pulse are applied is , which is opposite to the normal rotation described above, and as a result, the terminal potential of the detection resistor 30 becomes Vs ₁ <Vs 1 as shown in FIG. 10b.
It becomes Vs ₂ . Therefore, by comparing the magnitudes of Vs ₁ and Vs ₂ , it is possible to detect whether or not the rotor has operated normally due to the normal drive pulse. In our example Vs ₁
The potential difference between and Vs ₂ was about 0.4V. A potential difference of this degree can be easily detected. For example, in a configuration as shown in FIG. 9, the gate 31 is turned ON at the timing of the first detection pulse, and the capacitor 33 is charged with Vs ₁ , and then the potential Vs ₁ charged in the capacitor 33 is changed when the second detection pulse is applied. The voltage comparator 33 may determine whether the terminal potential Vs ₂ of the detection resistor 30 is large or small. This completes the explanation of the first method of rotor motion detection principles.Next, we will explain the principle of rotor motion detection from the voltage waveform induced in the coil by the free vibration of the rotor after the rotor is driven. explain. Figure 11a shows the induced voltage waveform of the coil generated at both ends of the high resistance when both ends of the coil are connected to a high resistance of several tens of kilohms after applying a normal driving pulse to the coil, and the rotation angle of the rotor. Figure 11b
This shows the angle between the stator parallel axis and the magnetic poles. Section T ₁ is the section where the drive pulse is normally applied to the coil, and the high resistance (detection resistor 7 is not connected to the circuit, so _no induced voltage waveform appears. This is the voltage induced in the coil by the rotation and vibration motion of the rotor after completion.The voltage waveform in this section _T2 changes depending on the step motor's load state and drive conditions, so the voltage waveform of this voltage waveform is By detecting the change, the operation of the step motor can be detected. Fig. 12 is an example of a detection circuit based on this principle. Gates 24, 25, 26, 27, 28, 2
9, the detection resistor 30, and the coil 7 have exactly the same configuration as in FIG. 9, except that the input signal is different. A connection point of the detection resistor 30 is connected to an input end of a voltage detector 40 having a predetermined threshold value. When the coil is energized in path 41 with a normal drive pulse, the rotor is driven. Then, during the rotor motion, the coil 7
The state is intermittently switched between a state in which both ends are grounded and short-circuited through the path 42, and a state in which a closed loop including the high-resistance detection resistor 30 is formed through the path 43. The effect of intermittent switching will be described later, but for the sake of simplicity, we will first describe a state in which a closed loop including the detection resistor 30 is formed immediately after the rotor is driven. FIG. 11 shows the terminal potential waveform of the detection resistor 30 in such a state. In FIG. 11, the step motor is in an almost no-load state. Next Figure 13a
In the figure, the induced voltage waveforms and rotor rotation angles at maximum load and overload are shown as a and b. θ is the angle between the stator parallel axis and the magnetic poles, as shown in FIG. 13b. At maximum load a, the rotor rotates slowly and the vibration after one step rotation is small, so the induced voltage has a waveform with few irregularities. Also, at overload b,
Except for a large peak voltage induced in the negative direction when the rotor returns to its initial position, the induced voltage waveform has little undulation. Various methods can be considered for determining whether the rotor is rotating or not rotating from the induced voltage waveform, but determining based on the presence or absence of the peak P shown in FIG. 11 is simple and reliable in terms of circuitry. In other words, it depends on whether or not the terminal potential of the detection resistor 30 reaches a predetermined potential or higher within a predetermined time period during which the peak P is considered to occur after the number of m seconds after the application of the normal drive pulse ends.
Determine whether the rotor is rotating or not. However, with this method, as shown in Figure 13a, even though it is rotating under maximum load, it is considered to be non-rotating. If it is used, it is a safe malfunction,
The rotor will not rotate too much because the corrective drive pulses in the same direction will simply be produced in excess. FIG. 14 shows the coil induced voltage waveform after driving when the pulse width of the normal driving pulse is varied. As can be seen from this figure, when the pulse width of the normal drive pulse exceeds a certain length, the height of the peak P of the induced voltage waveform becomes low despite no load and normal rotation.
To make this easier to understand, FIG. 15 shows the pulse width of the normal drive pulse on the horizontal axis and the potential of the peak P of the induced voltage on the vertical axis. 45 is a case where a detection resistor is connected in series with the coil after driving to form a closed loop as explained above, and 46 is a case where a detection resistor is intermittently connected in a closed loop as explained next. It is. Next, we will discuss the effect of intermittently connecting a high-resistance detection resistor in a closed loop that includes the coil after applying a normal drive pulse. Conventional drive circuits are driven by two inverters as shown in Figure 2, so when not driven, both ends of the motor coil are short-circuited due to the low resistance in the driver that forms the inverter, and the voltage induced in the coil is The current flowing through the twelfth
The current flows through the short circuit of path 42 in the figure, and this current is consumed as heat by the driver resistor transistor, thereby applying braking to the rotor.
Furthermore, in order to detect the induced voltage, when a closed loop is formed using the path 43 in FIG. is smaller compared to the former. Therefore, by switching these two circuits when braking the rotor, a sudden change in current occurs in the circuit. However, since the motor coil has a large inductance, it is unable to follow this change in current, and the braking circuit resistance Rd (=R + R
30) and the first-order lag response with time constant γ=Rd due to coil inductance L. At this time,
The voltage generated across the detection resistor 30 and R30 is:
When the braking circuit is on path 42 in Fig. 12, the voltage is zero, and the moment the switch is made to path 43, the coil 7 tries to keep the braking current flowing through path 42, so the detection resistance is relatively high. A high voltage is momentarily generated across the resistor 30, and then attenuates with the aforementioned time constant γ. An example of the terminal voltage of the detection resistor 30 at this time is shown in FIG. The feature of this method is that it is possible to amplify the voltage induced by the motor during braking by simply switching the resistance value of the circuit that performs rotor braking, and when the induced voltage is continuously detected as shown in Figure 15 45 The maximum value of the peak voltage of the high voltage is the height
While it is about 0.8V, in the case where the detection resistor is connected intermittently as shown in 46, it reaches the power supply voltage of the drive circuit (about 1.5V) or more. Therefore, it is extremely easy to detect such a voltage. By the way, as can be seen from FIG. 15, when the pulse width of the normal drive pulse exceeds a certain level, there is a phenomenon in which the undulations of the induced voltage become smaller, so this point must be taken into account. The principles of the two types of rotor motion detection circuits have been described above, but the gist of the present invention is to increase or decrease the normal drive pulse width, and the configuration of the step motor and the step motor motion detection circuit are important elements. However, it is not limited to what is described herein. Next, examples of the present invention will be described. FIG. 17 is a block diagram of the embodiment. Reference numeral 90 denotes an oscillation circuit, which typically uses a crystal resonator that oscillates at 32768 Hz. 91 is a frequency divider circuit, which has 15 stages of flip-flops for the above oscillation frequency.
The frequency is divided to obtain a timing of 1 second. Reference numeral 97 is a reset input for the clock. When the reset input is input, all the frequency division stages are reset, and at the same time as the timekeeping reset state is entered, a reset signal is also input to the control circuit 93, and the normal drive pulse immediately after the timekeeping reset state is released. The pulse width is set to the minimum pulse width among the pulse widths. A waveform synthesis circuit 92 synthesizes desired pulses from the output of the flip-flop obtained by the frequency dividing circuit 91 using an AND gate, a NOR gate, etc. into a waveform as shown in the time chart shown in FIG. Since this synthesis allows logically easy circuit design, a circuit diagram is omitted. FIG. 19 is a circuit diagram of the drive circuit 94 and the detection circuit 95 shown in FIG. 17, and the input terminal _T1 is the output of the control circuit 93 in _FIG . (abbreviation)), one of the step motor 96 output terminals is “H”.
Then, one of them becomes "L" (abbreviation for low level), and current flows to the step motor 96. The output of the control circuit 93 in FIG. 17 is input to the T ₂ terminal, and when T ₂ is set to "H", the Q signal of the flip-flop 100 is input to the EX/OR during that time, so the EX/OR The output of the flip-flop 100 becomes a negative logic to the output of the flip-flop 100, and the direction of the current flowing to the motor can be reversed. In this embodiment, when the rotation is not caused by the normal drive pulse, the correction pulse _P2 is used to drive, and then the pulse _P3 , which is in the opposite direction to _P2 , is applied again. This is because in an integral stator type motor, if correction drive is performed at P ₂ , the magnetic saturation time of the saturable magnetic path of the integral stator becomes longer in the next drive pulse, and the effective pulse width becomes shorter. , when performing _P2 correction drive, the reverse direction pulse _P3 is sent to the step motor 96.
By applying this to the coil, the stator is magnetized in the direction of the next driving pulse, shortening the time required for saturation of the integral part. The output T ₃ of the control circuit 93 shown in FIG. 17 is input to the input terminal T ₃ , and the rotation is detected using this pulse by the method of detecting the induced voltage after the rotor rotates as described above. When a pulse P ₀ with a period of 1 second is input to flip-flop (hereinafter abbreviated as F/F) 100, F/F10
0 is F/F that outputs 1/2Hz, and its output Q
is to EX・OR121, output is EX・OR122
is input. T ₂ is input to the other input terminals of EX・OR121, 122, and the output of EX・OR121 is the NOR gate 102, 103, EX・OR122
The outputs of are connected to NOR gates 104 and 105, respectively. The output of NOT gate 101 is NOR gate 10
3,104. The output _T3 of the control circuit 93 is passed through the NOT gate 120 to the NOR gate 1.
02,105. The output of NOR gate 102 is NMOSFET11
5 and the first input of NOR gate 106. The output of NOR gate 103 is the output of NOT gate 12
PMOSFET1 for step motor drive through 3
13 and a second input of NOR gate 106. The output of NOR gate 104 is NOT gate 124
PMOSFET11 for step motor drive
8 and the first input of NOR gate 107. The output of NOR gate 105 is NMOSFET11
6 and the second input of NOR gate 107. The output of the NOR gate 106 is connected to the step motor driving NMOSFET 114, and the NOR gate 107 is connected to the step motor driving NMOSFET 114.
Connected to 19. The power supply terminal V _DD is a + power supply input terminal,
The sources of PMOSFETs 113 and 118 are connected. NMOSFET114, 119 have their sources grounded, PMOSFET113, NMOSFET114
The drains of the step motor 96 are connected to each other, and are connected to the output terminal of the coil of the step motor 96 and the detection terminal.
Each is connected to the drain of the NMOSFET 115. PMOSFET 118 and NMOSFET 119 have their drains connected to each other, and are further connected to the other end output terminal of the coil of step motor 96 and the detection terminal.
Connected to the drain of NMOSFET116. The NMOSFETs 115 and 116 have their source electrodes connected to each other, and their connection point is connected to one end of a resistor 117. Further, the other end of the resistor 117 is grounded. The connection point between the NMOSFETs 115 and 116 and the resistor 117 is also connected to the + input of the comparator 110. Moreover, this connection point T ₀ is a rotor rotation/non-rotation signal, and a comparator 110 and a resistor 10
8,109, NMOSFET111 is the detection circuit 9
In this embodiment, if the detection signal T ₀ can be detected sufficiently by the threshold voltage of the CMOS gate circuit, it is also possible to use a CMOSNOT gate. Resistor 108 is connected to power supply voltage V _DD , the other end is connected to resistor 109 , and this connection point is connected to the negative input terminal of comparator 110 . The other end of the resistor 109 is an NMOSFET for inhibiting detection.
It is connected to the drain of 111 and grounded through the source. Further, the comparator 110 has a ground terminal.
It is connected to the drain of the NMOSFET 111 and grounded through the source. The output of the comparator 110 is a signal T ₄ outputted to the terminal 112 and inputted to the control circuit 93 . Further, the comparator used in the detection circuit 93 of the present invention is a comparator configured with CMOS,
Briefly explain the operation. FIG. 20 shows one embodiment of the comparator 110, FIG. 20a is a detailed explanatory diagram, and FIG. 20b is a block diagram. Terminal 164 is a "+" input terminal, terminal 165 is a "-" input terminal, terminal 166 is an output terminal, terminal T ₃
is an enable terminal. The functions are summarized in Table 1.

[Table] V _DD is the power supply terminal, PMOSFET160,
162 source electrodes, respectively. PMOSFET 160 has its gate and drain electrodes connected, and the connection point is PMOSFET 162.
and the drain of the NMOSFET 161, respectively. The gate of NMOSFET 161 is connected to terminal 164, and the source thereof is connected to the drain of NMOSFET 111. 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 is connected to the drain of NMOSFET 111 together with the source of NMOSFET 161. NMOSFET 111 has its source grounded and its gate connected to terminal _T3 . Also, the characteristics of NMOSFET161 and 163 are equal to each other, and furthermore, the characteristics of PMOSFET160 and 162 are equal to each other.
The properties of are made equal to each other. The operation of the comparator configured as above will be explained. When the enable terminal _P3 is "L", the NMOSFET 111 is turned off and the comparator does not operate. When terminal _T3 becomes “H”, NMOSFET111
Turns ON and the comparator operates. In addition, in this embodiment, the threshold voltage of the detection signal is set by resistors 108 and 109.
Because it is obtained by dividing the voltage of
1, the current flows only when the pulse _T3 becomes "H", thereby reducing the current in the circuit. When the input voltage V ₁ is applied to the terminal 164, the potential and current at the connection point 168 become as shown in FIG. 21a. In FIG. 21a, 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, so its saturation current is equal to I168. This situation is shown in the characteristics shown in FIG. 21 b162. On the other hand, 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, the potential V166 of the output terminal 166 becomes close to the "L" level. This situation is shown by operating point X in FIG. 21b. On the other hand, when V ₂ <V ₁ , the output V166 becomes "H" level, and the situation is shown in Fig. 21b Y
Indicated by Therefore, the functions are summarized as shown in Table 1. FIG. 22 is a circuit example of the control circuit 93 in FIG. 17. The output signal _T4 from the detection circuit 95 is SR-F/
It is input to the set input terminal S of F140. The signal _P1 from the waveform synthesis circuit 92 is sent to the SR-F/F 15 via the reset input terminal R of the RS-F/F, the clock input terminal of the binary counter 143, the input terminal of the AND gate 156, and the NOT gate 157.
It is input to the reset terminal R of No.8. AND gate 141 connects output signal P ₂ of waveform synthesis circuit 92 and SR
-Q output of F/F 140 is input. AND gate 142 connects output P ₃ of waveform synthesis circuit 92 and SR
-The output of F/F140 is input, and the output signal is
Input to the drive circuit as T ₂ . AND gate 1
59 receives the output P ₅ of the waveform synthesis circuit and the output of the SR-F/F, and its output signal T ₃ is input into the drive circuit 94 . In the embodiment, the binary counter 143 is composed of four stages of flip-flops, and the output signal of each stage is input to an AND gate. OR gate 1
45 receives the output of the AND gate 144 and the output of the AND gate 142. AND gate 146
The SR-F/F output and the output of the NAUD gate 147 are input. Updown counter 148
is for U/D input (up-down control input).
The output of AND gate 146, clock input C
The output of OR gate 145 is input. A clock reset signal 97 is input to the reset input R. In the embodiment, the up-down counter 148 has a three-stage flip-flop, and the output
Q ₁ , Q ₂ , and Q ₃ are each input to a NAND gate 147, and are also input to EX/OR gates 150 and 1, respectively.
51,152. AND gate 156
are the outputs P ₄ , P ₁ and SR of the waveform synthesis circuit 92
-F/F output is input. Binary counter 149 has AND gate 1 at clock input C.
59 output is input, and SR is input to reset input R.
-Q output of F/F 158 is input. In the embodiment, the binary counter 149 is composed of three stages of flip-flops, each of which outputs Q ₁ , Q ₂ ,
Q ₃ is input to the OR gate 154 and
The signals are input to EX/OR gates 150, 151, and 152, respectively. NOR gate 153 is EX/OR
The outputs of gates 150, 151, and 152 are input, and the output thereof is input to set input S of SR-F/F 158. The output of the AND gate 141, the output of the AND 142, the output of the OR gate 154, and the output _P0 of the waveform synthesis circuit 92 are input to the OR gate 155, and the output _T1 is input to the drive circuit. Next, the operation of the embodiment will be explained. When the rotor is rotating, the SR-F/F140 enters the set state by inputting the detection signal _T4 .
becomes “L”, so AND gates 141, 14
The outputs of 2,146,159 are all "L". Therefore, the output T ₃ of AND gate 159 is
The output _P5 signal of the waveform synthesis circuit becomes an "L" signal at the same time as the rotation is detected, and thereafter the detection circuit is prohibited. Further, when the U/D input of the up-down counter 148 is "H", it becomes a down counter when the up counter is "L", so it becomes a down counter when the rotor is rotating. At this time, the clock input C of the binary counter 143 receives the output P ₁ from the waveform synthesis circuit every second.
is input, so in the case of a four-stage flip-flop configuration as in the embodiment, the output of the AND gate 144 becomes "H" every 16 seconds, and the OR gate 1
45 to the clock input C of the up-down counter 148, and the up-down counter 1
The count of 48 is decremented by 1 every 16 seconds. On the other hand, since the output P ₄ of the waveform synthesis circuit 92 is a 2048Hz signal, the period is approximately 0.5 msec, and only when the output P ₁ of the waveform synthesis circuit 92 is “H”.
Binary counter 1 via AND gate 156
It is input to clock input C of 49. In the embodiment, binary counter 149 is comprised of a three-stage flip-flop. EX・OR150,15
1,152 constantly monitors whether the outputs of the binary counter 149 and the up-down counter 148 match, and when the contents match, the outputs of EX and OR all become "L", and the output of the NOR gate 153 becomes "H". Therefore, the SR-F/F158 is set, the output Q becomes “H”, and the binary counter 1
49 is reset. For this reason, OR gate 15
The output of 4 is a signal with a time width equal to the product of the count number of the up-down counter and 0.5m sec.
is output as On the other hand, if the output _T4 of the detection circuit 95 does not output an "H" signal even once within the detection time, it is determined that the rotor could not rotate with the first drive pulse, and the output of the SR-F/F 140 is Continue the “H” state. Therefore, the output of the AND gate 141 is the output _T2 from the waveform synthesis circuit 92, which is used as the output of the OR gate 155 to perform corrective driving of the motor. Also, the output of the AND gate 142 is
The output signal P ₃ of the waveform synthesis circuit 92 is output, and T ₂
It is input as a signal to the drive circuit 94, and at this time, it is controlled so that the current flows in the direction opposite to the direction of the current flowing through the coil of the step motor in the correction drive state, and it is also driven from the output _T1 of the OR gate 155. Since it is input to the circuit 94, the residual magnetic influence of the step motor can be removed, and the saturable magnetic path saturation time in the case of an integral stator is eliminated. Further, since the output of the SR-F/F 140 is "H", the output of the AND gate 146 becomes "H", and the U/D input of the up-down counter 148 becomes "H". The up-down counter 148 is set to an up-down counter, and the waveform synthesis circuit 92
The output P ₃ of is AND gate 142, OR gate 145
is input to the clock input C of the up-down counter 148 via the up-down counter 148. Therefore, the count content of the up-down counter 148 becomes +1, and the length of the driving pulse output next time becomes longer by 0.5 msec. The outputs Q ₁ , Q ₂ , Q ₃ of the flip-flops of the up-down counter 148 all become "H", and when the next up input is input, the contents of the counters all become "L". In order to prohibit this, when all the inputs of the NAND gate 147 become "H", the output of the AND gate 146 is set to "L", and the up/down counter 148 is set as a down counter so that all the inputs become "L". It is prohibited. The output P ₀ of the waveform synthesis circuit is for determining the minimum pulse width of the normal drive pulse. This is because when the pulse width starts from 0 m sec, energy loss is large until driving at a constant pulse width.
It is set to 1.9m sec. The up-down counter 148 is reset at the same time as the reset signal is input to the frequency divider circuit. Therefore, after the reset is released, the normal drive pulse is driven by a pulse determined by the pulse width of the output P ₀ of the waveform synthesis circuit 92. By the way, the pulse width of the output _P0 of this waveform synthesis circuit 92 is set to approximately the maximum length at which the step motor 96 cannot rotate, and after the reset is released, correction drive is always performed. . Therefore, it becomes easy to determine whether the correction circuit is good or bad when assembling the watch, and the inspection time can be shortened. Furthermore, the time required for the normal drive pulse width to become constant is quick because it only requires one or two correction drives. Therefore, the current consumption of the step motor can be measured quickly. If the step motor drive pulse has a pulse width so short that the step motor cannot rotate, the step motor cannot be driven with the normal drive pulse width. Therefore, since the output signal _T4 from the detection circuit is an "L" signal, the SR-F/F140 output is "H".
The output signal _P2 of the waveform synthesis circuit 92 is applied to the step motor 96 as a correction drive pulse. This pulse width is set to a width that can guarantee the maximum torque of the motor. In the example, this width is 7.8 m sec. And waveform synthesis circuit 9
When the output _P3 of 2 is input, the up-down counter 148 has become an up counter, so the counter content becomes +1. Therefore, if the drive pulse width for the first second is 1.9 m sec, the normal drive pulse for the second second is the output T ₁ of the waveform synthesis circuit = 1.9 m sec.
sec and 0.5 m sec, that is, the drive pulse has a length of 2.4 m sec. Furthermore, if the rotation cannot be completed with this pulse width,
Correction driving is performed for 7.8 msec, and then the up-down counter is set to 2 using the output _T3 of the waveform synthesis circuit 92. At the third second, the length of the normal drive pulse is 2.9 m sec. If the rotor cannot be rotated with this pulse width, the same operation is repeated and driving can be performed with a normal drive pulse width close to the limit at which the rotor can rotate. However, when the content of the binary counter 143 reaches 16, the output of the AND gate 144 becomes "H" and the content of the up-down counter 148 becomes -1. Therefore, for example, if normal driving is performed at 3.4 m sec, the next normal driving pulse of 2.9 m sec
sec. Therefore, if it can rotate at 2.9 m sec, it will continue to drive at 2.9 m sec, but
If the rotation cannot be completed with 2.9m sec, 2.9m sec.
sec, detects that it is not driven, rotates the rotor with a corrected drive pulse, increases the content of the up-down counter by 1, and the length of the next normal drive pulse becomes 3.4 msec again. Furthermore, in the case of a wristwatch with a calendar, the calendar is advanced for about 6 hours a day, which increases the load. In this case as well, the device that normally drives at 3.4 m sec now runs at 3.9 m sec and 4.4 m sec only during calendar feed.
It is now possible to drive with a pulse of m sec, and once the pulse has become long, it is shortened by 0.5 m sec after 16 seconds. This means that the motor can be driven with a pulse width that is just the limit that allows the rotor to rotate, reducing the power consumption of the motor. will be able to drive the clock in its lowest condition. In the embodiment, the binary counter 143 is a four-stage flip-flop binary counter.
A drive pulse and a correction drive pulse are issued at the same time once every 16 seconds. Therefore, when aiming to further reduce power consumption, by further increasing the number of stages of the binary counter 143, it is possible to reduce the rate at which both a normal drive pulse and a correction drive pulse are generated within a second. However, if the number of counter stages is increased too much, the load becomes large and the drive pulse width becomes long, and then when the load becomes small, it takes time to return to the original pulse width. Therefore, the number of stages of this binary counter becomes meaningless even if it is too large. As described above, according to the present invention, it becomes easy to test the function and performance of an electronic timepiece having the above-mentioned highly effective low power consumption drive circuit for a motor, which is highly effective. In addition, in this example, the explanation was given using a one-piece stator type motor, but this effect remains the same even with a two-piece stator type motor that has been conventionally used for watches, and the same great effect can be obtained. .

[Brief explanation of the drawing]

Fig. 1 is an example of the display mechanism of a general analog display type electronic wristwatch, Fig. 2 is an example of the circuit configuration of a conventional electronic wristwatch, Fig. 3 is an example of the drive current waveform of a step motor, and Fig. 4 is is an example of a drive pulse train according to the present invention; FIGS. 5, 6, and 7 are explanatory diagrams of a principle of rotor motion detection; FIG. 8 is an example of a drive current waveform of a step motor; and FIGS. FIG. 10 shows an example of a rotor operation detection circuit and an example of a detected voltage waveform, FIGS. 11 and 13 show the relationship between the rotation angle of the rotor and the induced voltage after the rotor is driven, and FIG. 12 shows the relationship between the rotor rotation angle and the induced voltage.
An example of a rotor operation detection circuit based on another principle, Fig. 14 shows the current waveform and induced voltage waveform when the drive pulse width is varied, and Fig. 15 shows the relationship between the drive pulse width and the subsequent peak potential. The graph shown in FIG. 16 is an example of the induced voltage waveform detected by rotor operation.
FIG. 17 is a block diagram of one embodiment of the present invention.
Figure 8 is a time chart of pulses necessary for this embodiment, Figure 19 is a configuration diagram of the drive circuit and detection circuit, Figures 20a and b are detailed configuration diagrams and block diagrams of the comparator, and Figures 21a and b. 22 is an explanatory diagram of the operation of the comparator, and FIG. 22 is a configuration example of the control circuit according to the present invention. 1... Stator, 6... Rotor, 7... Coil, 10... Crystal oscillation circuit, 11... Frequency dividing circuit,
12... Pulse synthesis circuit, 13a, 13b... Drive inverter, 90... Oscillation circuit, 91... Frequency division circuit, 92... Waveform synthesis circuit, 93... Control circuit, 94... Drive circuit, 95... ...motion detection circuit,
96...Step motor, 97...Reset input terminal.

Claims (1)

[Claims] 1. A step motor for moving the clock hands, a reference signal generation means for generating a time signal, and a drive pulse group having different effective powers and a correction pulse having a sufficiently large effective power by combining the outputs of the reference signal generation means. A waveform synthesis circuit that generates a waveform, a drive circuit that supplies one of the drive pulses to the step motor in synchronization with a time signal, and a drive circuit that detects rotation or non-rotation of the step motor immediately after the drive pulse is supplied. In an electronic watch comprising a detection circuit and a control circuit that supplies a correction pulse to a drive circuit to compensate for non-rotation when non-rotation is detected, the control circuit supplies a correction pulse to a drive circuit to compensate for the non-rotation when non-rotation is detected. A drive pulse with an effective power one level higher is supplied to the drive circuit, and when no rotation is detected for a predetermined period of time, a drive pulse with an effective power one level lower than the previous drive pulse is supplied. At the same time, when the step motor resumes rotation from a stopped state, a drive pulse having a minimum effective power is supplied from the waveform synthesis circuit to the drive circuit.