JPH0525704U - Solenoid drive circuit - Google Patents

Abstract

(57) [Abstract] [Objective] The present invention aims to reduce the number of transistors used to one, to reduce the cost, and to almost eliminate the heat generation of the circuit section. . According to the invention, a normal type solenoid 34, a switching transistor 33 having a collector and an emitter connected to a power source through the solenoid 34 in series, and a pulse having a duty ratio of 100% is provided on a base of the switching transistor 33. And a pulse selective input means 31 comprising a CPU for selectively inputting a pulse having a set duty ratio and making the solenoid 34 in an attracting state by a pulse having a duty ratio of 100% and holding the solenoid by a pulse having a set duty ratio. Be prepared.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a solenoid drive circuit that drives a solenoid.

[0002]

[Prior Art]

 Conventionally, solenoid drive circuits include a solenoid drive circuit that uses a self-holding solenoid and a solenoid drive circuit that uses a normal solenoid. In a solenoid drive circuit using a self-holding solenoid, a self-holding solenoid 9 is driven by four transistors 1 to 4 and two resistors 5 and 6 and inverters 7 and 8 as shown in FIG. There is something.

In this solenoid drive circuit, when a high level input signal is input to the input terminal 10 and a low level input signal is input to the input terminal 11, the transistors 1 and 2 are turned on and the transistors 3 and 4 are turned on. Is turned off, an on-current i ₁ flows from the power source Vcc to the self-holding solenoid 9 via the transistors 1 and 2, and the self-holding solenoid 9 is in an attracting state. When a high-level input signal is input to the input terminal 11 and a low-level input signal is input to the input terminal 10, the transistors 3 and 4 are turned on and the transistors 1 and 2 are turned off. The off-current i ₂ flows through the self-holding solenoid 9 through the solenoids 3 and 4, and the self-holding solenoid 9 is returned to the return state.

As another solenoid driving circuit using a self-holding solenoid, as shown in FIG. 8, a self-holding solenoid 15 with a tap T is formed by two transistors 12 and 13 and two resistors 14 and 15. There is something that drives.

In this solenoid drive circuit, when a high level input signal is input to the input terminal 17 and a low level input signal is input to the input terminal 18, the transistor 12 is turned on and the transistor 13 is turned off. The on-state current i ₁ flows from the power source Vcc through the transistor 12 to a portion below the tap T of the self-holding solenoid 16 to bring the self-holding solenoid 16 into an attracting state. When a high-level input signal is input to the input terminal 18 and a low-level input signal is input to the input terminal 17, the transistor 13 is turned on and the transistor 12 is turned off, so that the power source Vcc passes through the transistor 13. Then, the off-current i ₂ flows to a portion above the tap T of the self-holding solenoid 16 and the self-holding solenoid 16 is returned to the reset state.

As shown in FIG. 9, there is a solenoid drive circuit that uses a normal type solenoid to drive the normal type solenoid 24 by transistors 19, 20 and resistors 21 to 23, as shown in FIG.

In this solenoid drive circuit, when the normal type solenoid 24 is driven, a high level input signal is first input to the input terminal 25 and a low level input signal is input to the input terminal 26, so that the transistor 19 is turned on, the transistor 20 is turned off, and the current i flows from the power source Vcc to the normal type solenoid 24 through the transistor 19 to bring the normal type solenoid 24 into the attracting state. Then, when a high-level input signal is input to the input terminal 26 and a low-level input signal is input to the input terminal 25, the transistor 20 is turned on and the transistor 19 is turned off. A current i smaller than that in the suction state flows through the normal type solenoid 24 through 20 in series, and the normal type solenoid 24 is held. Further, when a low-level input signal is input to the input terminals 25 and 26, the transistors 19 and 20 are turned off, the current i does not flow through the normal solenoid 24, and the normal solenoid 24 returns to the recovery state.

[0008]

[Problems to be solved by the device]

 Since the solenoid drive circuits 1 to 4 are composed of four transistors 1 to 4 or two transistors 12, 13, 19 and 20, the number of transistors used is large. Moreover, in the solenoid drive circuit, since the self-holding solenoids 9 and 16 are used, the cost is higher than that in the case of using the normal solenoid. Further, in the above solenoid drive circuit, since the holding current is continuously supplied to the normal solenoid 24 via the resistor 21 after the normal solenoid 24 is attracted, the holding current is kept large. It must be used, and the resistor 21 generates a large amount of heat.

The present invention aims to provide a solenoid drive circuit which can improve the above-mentioned drawbacks, reduce the number of transistors used to one, reduce the cost, and substantially eliminate the heat generation in the circuit section. To aim.

[0010]

[Means for Solving the Problems]

 To achieve the above object, the present invention provides a normal type solenoid, a switching transistor having a collector and an emitter connected to a power source through the solenoid in series, and a duty ratio of 100% at a base of the switching transistor. Pulse and the pulse of the set duty ratio are selectively input, and the solenoid is attracted by the pulse of the duty ratio of 100%, and the solenoid is held by the pulse of the set duty ratio. Pulse selective input And means.

[0011]

[Action]

 When a pulse having a duty ratio of 100% is input to the base of the switching transistor by the pulse-selective input means, the normal solenoid is in the attracting state. Further, when a pulse having a set duty ratio is inputted to the base of the switching transistor by the pulse selective input means, the normal type solenoid is brought into a holding state.

[0012]

【Example】

 FIG. 1 shows an embodiment of the present invention. A one-chip microcomputer (hereinafter referred to as CPU) 31 selectively outputs a pulse width modulation pulse (PWM pulse) having a duty ratio of 100% and a PWM pulse having a smaller set duty ratio from the PWM output terminal P. The PWM output terminal P is connected to the base of the switching transistor 33 via the resistor 32. The emitter of the switching transistor 33 is grounded, and the collector is connected to the power supply Vpp through the normal type solenoid 34. A back electromotive voltage protection diode 35 is connected in parallel to the normal solenoid 34.

FIG. 2 shows a solenoid driving routine of the CPU 31. When starting the suction state of the normal type solenoid 34, the CPU 31 first outputs a PWM pulse having a duty ratio of 100% from the PWM output terminal P and starts counting the clock by a timer. A PWM pulse having a duty ratio of 100% from the PWM output terminal P of the CPU 31 is input to the base of the switching transistor 33 via the resistor 32, and the switching transistor 33 is continuously turned on. Therefore, the normal type solenoid 34 is in the attracting state due to the current Is flowing from the power source Vpp through the switching transistor 33, that is, attracting the load with the original attracting force. At this time, the PWM pulse Vin output from the PWM output terminal P of the CPU 31, the base input current Iin of the switching transistor 33, and the current Is flowing through the normal solenoid 34 are, for example, when the frequency of the PWM pulse Vin is low, as shown in FIG. When the frequency of the signal voltage Vin is high, the current Is flowing through the normal type solenoid 34 has a waveform as shown in FIG. 3B.

Next, the CPU 31 determines whether or not the time measured by the timer reaches the set time, and when the time measured by the timer reaches the set time, the PWM pulse from the PWM output terminal P is set to the set duty ratio. Switch to the PWM pulse of. Since the average current Is of the normal type solenoid 34 is proportional to the duty ratio of the PWM pulse Vin output from the PWM output terminal P of the CPU 31, the duty ratio of the PWM pulse Vin is switched from 100% to a smaller value. The average current Is of the normal type solenoid 34 is switched to a set value required to maintain the attracted state of the normal type solenoid 34, and the attracted state of the normal type solenoid 34 is maintained. Here, the set time and the set duty ratio are obtained by calculation or experiment, or set by sequentially decreasing the duty ratio of the PWM pulse Vin at the time of manufacturing the product to determine an appropriate value. Is set to 100 to 200 ms, and the set duty ratio is set to 30% to 50%.

Further, when the normal type solenoid 34 is restored, the duty ratio of the PWM pulse Vin output from the PWM output terminal P of the CPU 31 is switched to almost 0, the switching transistor 33 is turned off, and the normal type solenoid 34 is turned off. The solenoid 34 returns.

FIG. 4 shows a part of another embodiment of the present invention. In this embodiment, the lever 35 is connected to the shaft 34a of the normal type solenoid 34 in the above embodiment, and when the normal type solenoid 34 is returned, the shaft 34a and the lever 35 are in the positions indicated by the solid lines in FIG. When the normal solenoid 34 attracts the shaft 34a, the lever 36 moves to the position indicated by the dotted line in FIG. The photo sensor 37 does not detect the lever 36 when the normal solenoid 34 returns, and the output signal becomes high level, and when the normal solenoid 34 attracts the shaft 34a, the output signal becomes low level by detecting the lever 36. become. Further, in this embodiment, the solenoid drive routine of FIG. 5 is executed by the CPU 31 instead of the solenoid drive routine of FIG. 2 in the above embodiment. That is, when starting the suction state of the normal solenoid 34, the CPU 31 first outputs a PWM pulse having a duty ratio of 100% from the PWM output terminal P. Then, the CPU 31 checks the output signal of the photo sensor 37, and when the normal type solenoid 34 is in the suction state and the output signal of the photo sensor 37 becomes low level (L), the PWM pulse from the PWM output terminal P is output. By switching to the PWM pulse of the set duty ratio, the suction state of the normal type solenoid 34 is maintained.

FIG. 6 shows another embodiment of the present invention. In this embodiment, a constant current circuit 38, a pulse generator 39, a switching means 40 and a pulse selective input means consisting of a timer are used in place of the CPU 31 in the embodiment of FIG. 1, and the switching means 40 is operated by a timer. To do. That is, when the suction state of the normal type solenoid 34 is started, first, the timer starts timing and the constant current from the constant current circuit 38 passes through the switching means 40 and the resistor 32 to the base of the switching transistor 33. When the normal type solenoid 34 is input, a current flows from the power source Vpp through the switching transistor 33 and enters the attracting state. After that, when the timer measures a set time, for example, 100 ms to 200 ms, the switching means 40 is switched by the output signal of the timer, and the pulse from the pulse generator 39 with a duty ratio smaller than 100% is switched to the switching means 40. , Is input to the base of the switching transistor 33 through the resistor 32, and the average current Is of the normal type solenoid 34 is switched to a set value necessary for maintaining the suction state of the normal type solenoid 34, and the suction state of the normal type solenoid 34 is changed. Is retained.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and can be arbitrarily used in a mechanism for setting the normal solenoid in the suction state and then holding it.

[0019]

[Effect of the device]

 As described above, according to the present invention, a normal type solenoid, a switching transistor whose collector and emitter are connected to a power source through the solenoid in series, and a pulse having a duty ratio of 100% are provided on the base of the switching transistor. A pulse having a set duty ratio is selectively input, and a pulse having a duty ratio of 100% causes the solenoid to be in a suction state, and a pulse having a set duty ratio causes the solenoid to be held. Since it is provided, the number of transistors used can be reduced to one, and the cost can be reduced by using the normal type solenoid, and the heat generation of the circuit part can be almost eliminated.

[Submission date] January 10, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

[0018] The present invention is not limited to the above embodiments, it is possible to use a normal solenoid optionally in mechanism for holding the subsequently in the Aspirate state.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a solenoid driving routine of the CPU in the embodiment.

FIG. 3 is a waveform diagram showing a signal waveform of each part of the embodiment.

FIG. 4 is a plan view showing a part of another embodiment of the present invention.

FIG. 5 is a flowchart showing a solenoid driving routine of the CPU in the embodiment.

FIG. 6 is a circuit diagram showing another embodiment of the present invention.

FIG. 7 is a circuit diagram showing a conventional solenoid drive circuit.

FIG. 8 is a circuit diagram showing another conventional solenoid drive circuit.

FIG. 9 is a circuit diagram showing another conventional solenoid drive circuit.

[Explanation of symbols]

 31 CPU 33 Switching Transistor 34 Normal Solenoid 36 Lever 37 Photo Sensor 38 Constant Current Circuit 39 Pulse Generator 40 Switching Means

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[Procedure amendment]

[Submission date] January 10, 1992

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

Claims (1)

[Scope of utility model registration request] 1. A normal type solenoid, a switching transistor whose collector and emitter are connected to a power source through the solenoid in series, and a pulse having a duty ratio of 100% and a pulse having a set duty ratio at the base of the switching transistor. And a pulse-selective input means for selectively inputting and to bring the solenoid into a suction state with a pulse having a duty ratio of 100% and holding the solenoid with a pulse having a set duty ratio. Drive circuit.