JPS62252914A - Solenoid driving circuit - Google Patents

Abstract

PURPOSE:To reduce the size of a solenoid driving circuit by continuously outputting a control signal when a solenoid attracts, and intermittently outputting it when the solenoid sticks to decrease power consumption and the amount of heat generated with a simple configuration. CONSTITUTION:When a CPU 11 supplies a control signal to a solenoid 14, an input/output circuit 12 outputs a drive signal (a) to a driver 13. The signal (a) continuously becomes a low level during a predetermined period that the solenoid 14 needs to attract, and then repeats high and low levels. As a result, a transistor TR1 is turned OFF and a transistor TR2 is turned ON at attracting time so that a current I1 continuously flows to the solenoid 14. Since the TR1, TR2 repeat ON and OFF at the time of sticking, the current I1 and a circulating current I2 alternately flow to the solenoid 14. Thus, power consumption at the time of sticking is reduced, and the amount of heat generated is decreased. The size of the circuit can be also reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a solenoid drive circuit for driving a solenoid for switching a distribution gate or the like used in, for example, a thermal transfer copying machine.

(Prior Art) Conventionally, a solenoid performs a suction operation of a plunger by applying a predetermined voltage, and after suction, the plunger is maintained in a suction state by the same voltage. For this reason, even though there is no need to apply much current after suction, a large current is supplied to the solenoid in order to maintain the suction state. Therefore, there have been problems in that the power consumption increases and the amount of heat generated is large. Therefore, in the past, a resistor was used to drive the solenoid with a large current during suction and a small current during suction, or the same bobbin was used to change the current supplied during suction and suction. A method has been considered, such as providing a solenoid with a different number of turns to use two types of flow paths.

However, when using a resistor, there is a drawback that the resistor has to have a relatively large power, resulting in an increase in size. Furthermore, when the paths are provided separately, there is a drawback that the cost of the solenoid itself becomes high.

(Problems to be Solved by the Invention) This invention eliminates the drawbacks of the solenoid, such as increased power consumption, increased heat generation, larger size, and higher cost, and can reduce the consumed gI power with a relatively simple configuration. Moreover, it is an object of the present invention to provide a solenoid drive circuit that is compact and can reduce the amount of heat generated.

[Configuration of the Invention (Means for Solving Problems) The solenoid drive circuit of the present invention includes a solenoid in which a backflow prevention diode is connected in parallel, a drive means for driving the solenoid, and a drive means for the drive means. connected, and outputs a control signal continuously when the solenoid is suctioned,
It is comprised of a signal generating means that intermittently outputs a control signal when the solenoid is attracted.

(Operation) This invention continuously supplies a current flowing through the solenoid by continuously supplying a control signal to a solenoid in an attraction state, and a control signal to a solenoid in an attraction state. By intermittently supplying the current, the current flowing through the solenoid is continuously supplied within a range in which the attraction force of the solenoid does not fall below a predetermined value.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a solenoid drive circuit according to the present invention. Reference numeral 11 denotes a CPU (central processing unit) that outputs control signals for controlling the drive of solenoids, which will be described later. Reference numeral 12 denotes an input/output circuit having a plurality of ports, which responds to control signals for the solenoid supplied from the CPU 11. It outputs a drive signal. Above CPU
11 and the input/output circuit 12 constitute a signal generating means. Further, reference numeral 13 denotes a drive section serving as a drive means for driving the solenoid 14 using a drive signal supplied from the input/output circuit 12.

The drive section 13 is connected to the port P of the input/output circuit 12. That is, the base of the pre-drive transistor TR1 in the drive unit 13 is connected to the input/output circuit 12.
N
source v1. The emitter of this transistor TR1 is grounded. Further, the collector of the transistor TRI is connected to the li source v1 via a resistor R2, and is also connected to the base of a drive transistor TR2. The emitter of this transistor TR2 is grounded. Further, the collector of the transistor TR2 is connected to the power supply V2 via the solenoid 14. Furthermore, the anode of a diode D is connected to the collector of this transistor TR2, the cathode of this diode D is connected to the Ii source v2, and the diode D is connected in parallel to the solenoid 14.

Next, the operation based on such #l formation will be explained.

The input/output circuit 72 is connected to the solenoid 14 from the cpuii.
When the control signal is supplied, a drive signal as shown in FIG. 2(,a) is output to the drive unit 13. In other words, the CPU
In response to the control signal supplied from 11, the input/output device 12
A drive signal as shown in FIG. 2(a) is supplied from the boat P to the base of the pre-drive transistor TR1.

This drive signal is applied to the solenoid 14 during suction, for example.
is a low level signal during the period of 500m5 required for suction operation, and while the solenoid 14 is in the suction state during suction, the high level signal and low level signal are 5ms.
It is repeated every time.

Note that switching between high level signal and low level signal is done by C.
Since this is done using the clock signal of the PU 11, it can be easily changed.

As a result, during attraction, the transistor TR1 is turned off by the low level signal supplied from the input/output circuit 12, so that the base of the transistor TR2 is supplied with the high level signal shown in FIG. 3(b). Then,
Transistor TR2 turns on, and solenoid 14
A current (1) as shown in FIG. 2(C) flows through. Therefore, the solenoid 14 performs the suction operation by being continuously supplied with the current (1).

After the suction operation of 500 m5 is completed, during suction, the transistor TRI is turned on by the high level signal supplied from the input/output circuit 12, so the base of the transistor TR2 is supplied with the low level signal shown in FIG. is supplied. Then, by turning off the transistor TR2, a back electromotive force is generated, and the solenoid 1
A current I2 as shown in FIG. 4 (C) flows through the current I2. Then, the transistor TR1 is turned off by the low level signal supplied from the input/output circuit 12, so that the high level signal shown in FIG. 2(b) is supplied to the base of the transistor TR2. Then, it goes off. Hereinafter, the input/output circuit 12
As the high level signal and low level signal are repeatedly supplied from
plays repeatedly. Therefore, even if the drive signal is intermittent, currents 11 & 5 and 12 are continuously supplied to the solenoid 14, thereby maintaining the adsorption state. That is, as shown in FIG. 3, the relationship between the stroke and the suction/adsorption force in the solenoid is such that as the stroke becomes larger, the suction/adsorption force decreases, and as the stroke becomes smaller, it increases. Therefore, the adsorption force of the solenoid in the adsorption state is very large, so even if the drive signal is intermittent and the flow becomes small, adsorption can be maintained.

As mentioned above, when suction requires large force, 10
The solenoid 14 is driven with a large force by outputting a drive signal with a duty of 0%, and the solenoid 14 is driven with the minimum required force by intermittently outputting a drive signal during adsorption. This eliminates the need for extra current to be supplied during adsorption, making it possible to prevent heat generation and reduce power consumption. Therefore, small solenoids can be used without the need for special resistances or paths.

Note that in the above embodiment, the input/output circuit 12 is
The drive signal from is switched at a duty ratio of 5ms, but if the low level of the drive signal becomes long, the current becomes intermittent and the solenoid's adsorption force decreases, but if it is within a range where the current does not become intermittent, for example, it can be changed. It is possible.

Note that in the above embodiment, the input/output circuit 12 is
For example, the input/output circuit 12 may generate a drive signal in accordance with the sentence signal supplied from the CPU 11.

[Effects of the Invention] As described above in detail, the present invention can provide a solenoid drive circuit that can reduce the amount of power consumed by a relatively simple configuration, is small in size, and can reduce heat generation. .

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a block diagram schematically showing a solenoid drive circuit, FIG. 2 is a timing chart shown to explain the operation, and FIG. 3 is a solenoid suction diagram. FIG. 3 is a diagram showing characteristics. 11...CPU, 12...I/O circuit, 13...
Drive unit, 14... Solenoid, TR1, TR2...
Transistor, D...diode.

Claims (2)

[Claims] (1) A solenoid in which a backflow prevention diode is connected in parallel, a driving means for driving this solenoid, and a control signal connected to this driving means, which continuously outputs a control signal when the solenoid is suctioning, and intermittently outputs a control signal when the solenoid is suctioning. 1. A solenoid drive circuit comprising: signal generation means for outputting a control signal to the solenoid drive circuit. (2) The signal generating means is capable of arbitrarily setting the timing of the control signal that is intermittently output when the solenoid is attracted within a range where the current flowing through the solenoid is continuous. The solenoid drive circuit described.