JPH0514239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetic drive circuit used for driving a pendulum or the like.

[Prior Art] For example, there is a drive circuit shown in FIG. 8 that detects and drives the pendulum of a clock using one coil. In this circuit, an induced voltage is generated in coil _L2 by the passage of a permanent magnet fixed to the pendulum.
When this exceeds the reference voltage, transistor T ₂ is turned off, transistor T ₁ is turned on and drive current flows through coil L ₂ . this transistor
The on-time t of T ₁ is determined by the time constants of capacitor C and resistor R ₁ .

In order to drive the magnet efficiently, it is preferable to drive at the maximum point of the induced voltage, and in order to drive at this timing, the reference voltage and drive time t are set in advance to constant values.

[Problems to be Solved] The above circuit configuration is difficult to integrate, and is contrary to miniaturization and cost reduction.

In addition, when the pendulum is started from a stopped state using the above circuit, a driving pulse of width t is generated at a constant period, but since this is the same pulse as the normal driving pulse, one pulse is sufficient to pull the pendulum. The amplitude that can be generated is small. Moreover, since the amplitude of the induced voltage generated in coil _L2 is low, it is not possible to generate drive pulses in synchronization with the generation of this induced voltage, and the drive is performed at a long cycle determined by the time constant of the circuit configuration shown in Figure 8. A pulse will be generated. Therefore, the vibration caused by the drive pulse is attenuated, and the drive cannot be synchronized with the vibration of the pendulum, resulting in a disadvantage that the desired swing angle cannot be obtained.

In addition, since the reference voltage and drive pulse width are fixed, the reference voltage and drive pulse width must be set to appropriate values each time according to the swing angle and period of the pendulum, making the adjustment work complicated and complicated. Ta.

A first object of the present invention is to enable integration of most of the circuit configurations in a device that detects and drives a permanent magnet using one coil.

A second object of the present invention is to make it possible to reliably start up the swing angle from a stopped state to a desired swing angle.

A third object of the present invention is to automatically adjust the reference voltage optimally.

[Means for Solving the Problems] The present invention provides a comparator circuit that generates an output when the induced voltage of a coil that detects and drives a permanent magnet exceeds a reference voltage. A pulse generation circuit is provided that generates a drive pulse in response, and this drive pulse causes a drive current to flow through the coil.When the induced voltage remains below a specified level for a certain period of time, a starting pulse is generated. The first and second objectives are achieved by applying a large driving force to the permanent magnet.

Further, the third objective is achieved by receiving the output from the comparison circuit and controlling the reference voltage according to the amplitude of the induced voltage.

[Embodiment] In FIG. 1, V _r is a reference voltage source, and the reference voltage is variable. CM is a comparator circuit that generates an output when the induced voltage in the coil _L1 exceeds the reference voltage _vr . T is a drive circuit consisting of a transistor. TM is a timer circuit, and the timer time is set to a time longer than one cycle of the pendulum. PG is a pulse generation circuit that generates drive pulses with optimal timing and pulse width, the details of which will be described later. W ₁ is a one-shot circuit for a mask to prevent malfunction, W ₂
is a starting circuit consisting of a one-shot circuit for generating a starting pulse, G ₁ and G ₂ are gate circuits, and CT is an up-down counter for adjusting the reference voltage, which constitutes a control circuit. By this counter CT and timer circuit TM, the detection circuit DT is
It consists of

Next, the operation will be explained with reference to FIG. First, the operation when the power is turned on will be explained. When the power is turned on, an initial reset operation is performed, and the counter CT and timer circuit TM are reset. By resetting the counter CT, the reference voltage source V _r is set to the lowest level reference voltage. On the other hand, the output terminal p of the counter CT is “1”
, and the startup circuit _W2 becomes ready for operation.

Further, the timer circuit TM is supplied with a clock pulse of a constant period from the terminal CL, and generates an output when it measures a time longer than one period of the pendulum.

Since the pendulum is now stopped, no induced voltage is generated from the coil _L1 , and the timer circuit TM is not reset. Therefore, after a predetermined time, the timer circuit
An output is generated from TM, and the starting circuit _W2 is triggered to generate a starting pulse having a width longer than the normal driving pulse, as shown in FIG. This starting pulse turns on the drive circuit T, causing current to flow through the coil _L1 and starting the pendulum. Since the starting pulse width at this time is longer than normal, a large starting force is applied and the pendulum vibrates greatly.

At this time, the induced voltage generated in the coil L ₁ exceeds the reference voltage v _r as shown in FIG. 2, and the comparator circuit CM generates an output as shown in FIG. However, this output is prohibited from passing through the gate circuit G1 by the starting pulse and the pulse from the one-shot circuit _W1 (FIG. ₂ ) generated by the fall of the starting pulse.

When the pendulum is swung by the above activation and the induced voltage in coil _L1 exceeds the reference voltage v _r , the comparator circuit CM
An output is generated as shown in FIG. 2, and the pulse generating circuit PG is triggered to generate the normal drive pulse shown in FIG. By this drive pulse, the drive circuit T
turns on, driving current flows through coil _L1 , and the pendulum is driven synchronously.

On the other hand, the timer circuit TM is reset by the above output from the gate circuit _G1 , the counter CT counts up by one, and the reference voltage of the reference voltage source _Vr rises by one level. Also counter CT
The terminal P of is inverted to "0", and the starting circuit _W2 is kept in an inoperative state.

The above operation is repeated, and each time the induced voltage of the coil _L1 exceeds the reference voltage, the counter CT counts up and the reference voltage increases. When the induced voltage no longer reaches the reference voltage, the comparator circuit CM no longer generates an output, and the timer circuit
Since the TM is not reset, an output is generated from the timer circuit TM after a certain period of time, and the counter CT
counts down by one. At this time, the starting circuit
_W2 is also triggered, but no activation pulse is generated since it is held inactive by the output from terminal p.

The reference voltage is lowered by one level due to the above-mentioned down-counting of the counter CT.

Through this operation, the reference voltage is automatically set to the optimum value, and the pendulum oscillates with the desired amplitude.

In the above embodiment, in order to simplify the explanation, the reference voltage is increased every time one driving pulse is generated, but in reality, the driving pulse is increased n times (n=2, 3...). It is preferable to increase the reference voltage by one step when the above occurrences occur continuously. In this case, a circuit that generates one pulse when n pulses are counted using an n-ary counter (not shown) that counts the number of drive pulses generated is provided, and this output is used to count up the counter CT. Use as input. The n-ary counter is reset by the output of the timer circuit TM.

Also, depending on the contents of the counter CT, the timer circuit
The TM timer time may be changed. In other words, when driving a short-period pendulum, the amplitude of the induced voltage generally increases, and therefore the content of the counter CT increases. Therefore, if the content of the counter CT is large, it is assumed that the period of the pendulum is short, and the timer time is switched to a short time.

Next, a specific example of the pulse generation circuit PG will be explained. In Figure 3, G ₃ and G ₄ are gate circuits,
_F1 is a flip-flop circuit, and IN is an inverter. W ₃ and W ₄ are one-shot pulse generation circuits, and their respective pulse widths are set to t ₁ and t ₂ . Note that the same reference numerals as in FIG. 1 indicate the same things.

In the above configuration, when no output is generated from the comparison circuit CM, the one shot pulse generation circuits W ₃ and W ₄ are set and reset, respectively, by the output of the gate circuit G ₃ .

Therefore, when the induced voltage in the coil _L1 exceeds the reference voltage v _r as shown in Fig. 4, the fourth
An output is generated as shown in the figure, and the setting and resetting of the one-shot pulse generation circuits W ₃ and W ₄ are canceled via the gate circuit G ₃ . Therefore, the output of the one-shot pulse generation circuit _W3 is inverted to " ₀ " after time _t1 as shown in _FIG . A pulse with a width of is generated. In this way, the one shot pulse generation circuits W ₃ and W ₄ oscillate, and the drive pulse train shown in FIG. 4 is generated from the output of the one shot pulse generation circuit W ₃ . The flip-flop circuit _F1 is triggered by the rise of the first pulse of this drive pulse train, and its output Q is held at "1" as shown in FIG. Therefore, as shown in FIG. 4, the output of the gate circuit _G3 is held at "1" from the generation of the output of the comparator circuit CM, and the drive pulse train is generated from the gate circuit _G4 as shown in FIG. This drive pulse train turns on the transistor T, causing a drive current to flow through the coil _L1 .

The above drive pulse train is a flip-flop circuit _F1
The output state of the comparator circuit CM is determined based on the rising edge of the clock. Therefore, while the comparator circuit CM is generating output, the above drive pulse train is generated and the coil _L1
is driven.

When the induced voltage becomes lower than the reference voltage v _r and the output of the comparator circuit CM stops, the output of the flip-flop circuit _F1 is inverted to "0" by the first rise of the drive pulse, and the drive pulse train is changed. The coil _L1 stops driving.

As described above, the drive current flows through the coil while the induced voltage exceeds the reference voltage v _r .

When the above circuit is used as the pulse generating circuit PG, the output of the gate circuit _G1 is used as the input of the gate circuit G shown in FIG. 1, the reset input of the timer circuit TM, and the set input of the flip-flop circuit F.

Incidentally, although omitted in the above explanation, the output width _t2 of the one-shot pulse generation circuit _W4 is set as follows. Since the coil _L1 is driven by a drive pulse train, when this pulse is interrupted, the ringing r normally occurs for 1ms as shown in Figure 4.
Occurs to some extent. While this ringing occurs, the coil
Since the induced voltage in _L1 becomes unstable, the next drive pulse is generated during this time and the flip-flop circuit is activated.
If the output of the comparator circuit CM is determined by _F1 , there is a risk of malfunction. Therefore, the output width t ₂ of the one-shot pulse generation circuit W ₄ is adjusted so that the next drive pulse is generated while the induced voltage is stable.
is set to about several milliseconds.

Note that when driving the coil, even if there is a drive stop time of about several milliseconds, it does not affect the energization of the permanent magnet and can be ignored.

In the above embodiment, the reference voltage v _r that determines the drive start timing and the drive stop timing is set to be the same voltage, but the drive end timing may be adjusted by making them different. For example, by switching the reference voltage to the voltage v _r1 as shown in FIG. 4 using the output of the flip-flop circuit _F1 , the last drive pulse can be prevented from being generated. This allows more fine adjustment of the drive time.

Incidentally, the amplitude of the induced voltage is generally affected by fluctuations in the power supply voltage. When the amplitude of the induced voltage fluctuates, the timing at which the induced voltage exceeds the reference voltage shifts, resulting in fluctuations in drive timing and drive time. Therefore,
In order to reduce the influence of power supply fluctuations, the reference voltage v _r is set to a low voltage that is less affected by voltage fluctuations, and the output from the comparator circuit is delayed for a certain period of time by a delay circuit (not shown). Alternatively, the driving may be started from this point. For example, as shown in Figure 4, the reference voltage is set to a low voltage v _r2
By setting it to , the induced voltage becomes voltage v _r2
An output is generated from the comparator circuit when it exceeds
This is delayed by a time _t0 by a delay circuit and then supplied to the flip-flop circuit _F1 and the gate circuit _G3 . This makes it possible to reduce the influence of fluctuations in power supply voltage, and to drive the coil at optimal timing and drive time.

Next, another example of the pulse generation circuit PG will be explained. In Fig. 5, _F2 is a flip-flop circuit, _W5 to _W8 are one-shot pulse generation circuits, and one-shot pulse generation circuit _W6 uses a programmable one-shot circuit with variable output pulse width. Generation circuit W ₅ ,
The pulse widths of W ₇ and W ₈ are set to t ₃ , T ₅ , and t ₆ , respectively. CT ₁ is an up-down counter.

In the above configuration, the contents of counter _CT1 are u
Assume that the pulse width is set to _t4 of the one-shot pulse generation circuit _W4 .

When the induced voltage exceeds the reference voltage v _r , an output is generated from the comparator circuit CM as shown in Figure 6.
One-shot pulse generation circuit _W5 is triggered,
A pulse of width t ₃ is generated. Due to the falling edge of this pulse, the one-shot pulse generation circuit _W6 changes to the width _t4.
A driving pulse is generated, transistor T is turned on, and a driving current flows through coil _L1 .

Due to the fall of this drive pulse, a pulse with a width _t5 is generated from the one-shot pulse generation circuit _W7 .
The falling edge triggers the flip-flop circuit _F2 and the one-shot pulse generating circuit _W8 . The D input of the flip-flop circuit _F2 is supplied with the output of the comparator circuit CM, and the output state is read into the flip-flop circuit _F2 . That is, it is determined whether the level of the induced voltage at the falling edge of the pulse from the one-shot pulse generating circuit _W7 exceeds the reference voltage _vr . If the reference voltage is exceeded, the output of the flip-flop circuit _F2 becomes “1” and the counter
CT ₁ goes into up mode. That is, in this case, it is determined that the drive pulse width is short and that the induced voltage is not generated efficiently around the maximum point.

On the other hand, due to the fall of the pulse from the one-shot pulse generating circuit _W7 , a pulse with a width _t6 is generated from the one-shot pulse generating circuit _W8 , and this becomes the clock input of the counter _CT1 . As a result, the contents of the counter CT1 increase by one, and become (u+1) as shown in FIG. 6p. Therefore, the pulse width of the one-shot pulse generation circuit _W6 is set to be longer than the previous one.

Therefore, next time, the driving pulse width will be longer,
The pulse width of the drive pulse is corrected.

This operation is repeated and the contents of the counter become m
Assume that the driving pulse width becomes t ₄ ' as shown in FIG. At this time, when the induced voltage level at the falling edge of the pulse from the one-shot pulse generation circuit _W7 becomes less than the reference voltage, the output of the flip-flop circuit _F2 becomes "0" as shown in FIG.
counter _CT1 goes into down mode.
Therefore, the content of the counter _CT1 decreases to (m-1), and the next drive pulse width becomes shorter by one step.

Therefore, the driving pulse width is stabilized by being alternately switched to t ₄ ' and one step shorter than t 4 '.

In this way, the drive pulse width is automatically stabilized at a predetermined width at an optimal timing, and the swing angle can be stabilized at a constant value.

In the above example, only the drive pulse width is adjusted, but programmable one-shot circuits are used as the one-shot pulse generation circuits W ₅ and W ₇ , and these pulse widths can also be adjusted by the counter.
It may be adjusted as appropriate depending on the content of CT ₁ . For example, if you want to set the pendulum's swing angle small, in a stable state the amplitude of the induced voltage will be
Since the change is small and changes slowly, it is necessary to stabilize the time t ₃ to _{t 5} in a slightly longer state as shown in the figure. Further, when it is desired to set the swing angle of the pendulum to be large, in a stable state, the amplitude of the induced voltage becomes large and its change becomes steep, as shown in FIG. 7b, and the width of the driving pulse may be short.
Therefore, it is necessary to stabilize the time t ₃ to _{t 5} in a relatively short time compared to that in FIG. 7a.

In the state of FIG. 7a and the state of FIG. 7b, the time
The ratio of time t ₄ to t ₃ and t ₅ is different, and by adjusting this ratio, a stable swing angle can be set. For example, if you want to stabilize the state shown in Figure 7b, set the pulse widths of the one-shot pulse generation circuits _W5 to _W7 so that each time has the ratio shown in the figure, and change the contents of the counter _CT1 . The pulse width is set so that each pulse width is changed according to the ratio while maintaining this ratio.

Therefore, by automatically adjusting the times t ₃ to _{t 5} as described below, the desired swing angle is stabilized. Depending on the contents of counter CT ₁ in the initial state, one shot pulse generation circuit W ₅ ~
It is assumed that the pulse width of W ₇ is set to the value shown in FIG. 7b. When the power is turned on in this state, the pendulum starts to vibrate, but since the swing angle is initially small, an induced voltage similar to that shown in FIG. 7a is generated. Therefore, at the falling edge of the pulse from the one-shot pulse generation circuit _W7 , the induced voltage exceeds the reference voltage, and the drive pulse width is determined to be short, and the counter
The contents of CT ₁ are uploaded by one, and times t ₃ to _{t 5} are set to one step longer. This operation is repeated and the time t ₃ to t ₅ increases step by step. In this way, the driving pulse width gradually increases, and following this, the swing angle of the pendulum gradually increases with a slight delay, and the amplitude of the induced voltage also increases accordingly.

Therefore, at a certain point, the drive pulse width becomes excessive, the counter _CT1 switches to the down mode, and the time period _t3 to _t5 decreases. Following this, the swing angle of the pendulum becomes smaller with a slight delay.

By repeating the above operations, the state approaches the state shown in FIG. 7b, and eventually becomes stable in this state. In other words, automatic adjustment is performed so that driving is performed efficiently with the optimum drive pulse width at the maximum point of the induced voltage.

By the way, the pulse width _t5 of the one-shot pulse generation circuit _W7 is set so that the timing of the induced voltage level judgment is performed at the point where the induced voltage is easiest to judge. The settings are made taking into consideration the ringing mentioned above.

In the above embodiment, the reference voltage for determining the drive start timing and the reference voltage for determining the induced voltage level after the end of the drive are the same voltage vr, but the latter is changed according to the contents of the counter _CT1 . It's okay. For example, the reference voltage is switched to a voltage corresponding to the contents of the counter _CT1 only while output pulses from the one-shot pulse generating circuits _W6 to _W8 are being generated. This has the same meaning as adjusting the pulse width of the one-shot pulse generation circuit _W7 .

Note that, unless fluctuations in the power supply voltage are taken into account, the one-shot pulse generation circuit _W5 is not necessarily required, and the output of the comparison circuit CM may be directly supplied to the one-shot pulse generation circuit _W6 .

Furthermore, in the above embodiment, a clock pulse is supplied to the counter CT ₁ every drive pulse, but for example, when the up/down mode of the counter CT ₁ is constant for three consecutive drive pulses, the clock pulse is supplied to the counter CT 1 for each driving pulse. You may upload one content of ₁ . The same applies to the down mode.

In this case, one shot pulse generation circuit W
A ternary counter may be provided between the flip-flop circuit F2 and the counter CT1, and this counter may be configured to be reset each time the output level of the flip-flop circuit _F2 is inverted. This makes it possible to prevent malfunctions caused by noise or the like.

[Effects of the Invention] According to the present invention, when the induced voltage in the coil exceeds a reference voltage, the comparator circuit generates an output, and the coil is driven in response to this output, so that the induced voltage is at a specified level. When the following conditions continue for more than a certain period of time, a starting pulse that provides a large driving force is generated, making it possible to integrate most of the circuit configuration, which is highly effective in reducing costs. Furthermore, even if the permanent magnet is stopped when the power is turned on or due to an external force, the permanent magnet can be started automatically. Moreover, even if the permanent magnet is held down by some kind of obstacle, only the current consumption due to the activation pulses generated at regular intervals is sufficient, and unnecessary current consumption can be suppressed as much as possible.

In addition, by controlling the reference voltage according to the amplitude of the induced voltage, it is possible to eliminate the inconvenience of drive pulses occurring at locations other than the maximum point of the induced voltage, and drive efficiently at the maximum point of the induced voltage. Automatic control is performed in this manner, and the permanent magnet can be efficiently driven with stable amplitude.

[Brief explanation of drawings]

Fig. 1 is a logic circuit diagram showing an embodiment of the present invention, Fig. 2 is a voltage waveform diagram for explaining the operation of Fig. 1, and Fig. 3 is a logic diagram showing a part of Fig. 1 in detail. The circuit diagram, Fig. 4 is a voltage waveform diagram for explaining the operation of Fig. 3, Fig. 5 is a logic circuit diagram showing another example of Fig. 3, and Figs. 6 and 7 are the diagrams of Fig. 5. A voltage waveform diagram for explaining the operation, and FIG. 8 is an electric circuit diagram showing an example of a conventional drive circuit. _L1 ...Coil, _Vr ...Reference voltage source, CM...Comparison circuit, PG...Pulse generation circuit, TM...Timer circuit, T...Drive circuit, CT...Control circuit,
DT...detection circuit.

Claims (1)

[Claims] 1. A coil that detects and drives a permanent magnet, a reference voltage source that generates a reference voltage, a comparison circuit that produces an output when the induced voltage of the coil exceeds the reference voltage, and this comparison circuit. a pulse generation circuit that generates a drive pulse in response to an output from the coil; a drive circuit that operates in response to the drive pulse and causes a drive current to flow through the coil; and a drive circuit that receives the output of the comparison circuit and determines the amplitude of the induced voltage. A detection circuit that detects that a state below a specified level has continued for a certain period of time, and a detection output from this detection circuit generates a starting pulse that provides a driving force greater than the driving pulse and supplies it to the driving circuit. An electromagnetic drive circuit consisting of a starting circuit. 2. A coil for detecting and driving a permanent magnet, a reference voltage source with a variable reference voltage, a comparator circuit that produces an output when the induced voltage of the coil exceeds the reference voltage, and a comparator circuit that generates an output from this comparator circuit. a pulse generation circuit that generates a drive pulse in response; a drive circuit that operates in response to the drive pulse and causes a drive current to flow through the coil; and a drive circuit that receives the output of the comparison circuit and adjusts the reference voltage according to the amplitude of the induced voltage. a timer circuit that generates an output when no output is generated from the comparator circuit for a certain period of time; and a timer circuit that generates an output when the comparator circuit does not generate an output for a certain period of time; An electromagnetic drive circuit comprising: a starter circuit that generates a starter pulse that provides a larger driving force than the drive pulse when an output is generated from the timer circuit, and supplies the generated starter pulse to the drive circuit.