JPS5923372Y2 - Plunger drive circuit - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a plunger drive circuit.

The recently popular switching mechanism for each operation in a tape recorder called a button switch includes a mechanical type that uses the pressing force of a push button, and an electric type that uses the suction force of a plunger.

Although plunger systems are more expensive than mechanical systems, they are easier to operate and are often used in high-end tape recorders.

In a tape recorder using such a plunger, it is necessary to maintain the plunger in the suction operation state even after switching to each operation state by the suction operation of the plunger, so that the plunger continues to be energized.

Therefore, such devices have problems with heat generation and power consumption from the plunger.

The plunger requires a large current at the start of suction, but the holding current after the suction operation can be made smaller compared to when the suction is started.

Conventionally, drive circuits have been developed that solve the above-mentioned problems by utilizing the characteristics of such plungers, but there have been problems such as the circuit becoming complicated and power consumption due to resistance.

The present invention has been developed in view of these points, and will be described in detail below with reference to the drawings.

The illustrated circuit is an embodiment of the present invention.
The emitter path is connected, and a capacitor 4 is connected between the base and ground.

A power supply transistor 5 is a bias resistor of the transistor 1.

Reference numeral 6 denotes a driving transistor whose collector is connected as a load to the plunger 2, whose emitter is grounded, and whose base is connected to the power supply path 3 via a switch 7 and a resistor 8; A bias control resistor 9 is connected between the base of the power supply transistor 1 and the bias control resistor 9 for controlling the bias of the transistor 1 after the plunger 2 has been sucked.

The plunger drive circuit of the present invention is constructed as described above, and the operation of this circuit will now be described.

When the switch 7 is in the open state, the driving transistor 6 is in a non-conducting state and the capacitor 4 is in a charged state.

In such a state, when the switch 7 is closed, the drive transistor 6 becomes conductive and the plunger 2 is energized, causing the plunger 2 to perform a suction operation, but at the start of this suction operation, the base potential of the power supply transistor 1 is the same as that of the capacitor. The power supply transistor 1 is deeply biased because it is held at a high potential for a short time due to the discharging operation of the charges stored in the power supply transistor 4 .

As a result, the potential of the power supply path 3, which is the emitter of the power supply transistor 1, is maintained at a high potential.

Therefore, at the start of suction, a large current flows through the plunger 2, and the plunger 2 performs a suction operation.

When the suction operation of the plunger 2 is completed, the charge stored in the capacitor 4 is discharged, and the base potential of the power supply transistor 1 is determined by the voltage division between the bias resistor 5 and the bias control resistor 9.

Therefore, if the bias by the bias resistor 5 and the bias control resistor 9 is set to be shallower than when the plunger 2 starts the suction operation, the emitter potential of the power supply transistor 1, that is, the potential of the power supply path 3 will decrease. Therefore, the attraction and holding current of the plunger 2 can be reduced.

As explained above, the plunger drive circuit of the present invention changes the holding current after the plunger suction operation by changing the bias of the transistor that supplies power to the plunger using the 1 to run sister that drives the plunger. This arrangement has the advantage that not only can the settings be made accurately, but also that the circuit configuration can be simplified.

[Brief explanation of the drawing]

The illustrated circuit is one embodiment of the plunger drive circuit of the present invention. Explanation of main drawing numbers 1...Power supply transistor, 2...
...Plunger, 3...Power supply path, 4...
... Capacitor 6 ... Drive transistor

Claims (1)

[Scope of utility model registration request] a power supply transistor whose collector is connected to a power supply and whose emitter is connected to a plunger as a load; a bias resistor connected between the collector and base of the power supply transistor; a capacitor connected between the base and ground; and a driving transistor, the plunger being connected as a load to the collector, and the collector being connected to the base of the power supply transistor via a bias control resistor. and when the driving transistor is inverted to a conductive state, the base bias of the power supply transistor is deepened for a short time by a discharge operation of the electric charge stored in the capacitor, and a high voltage is applied to the plunger; 2. A plunger drive circuit, characterized in that, after the plunger is sucked, the bias control resistor causes the base bias of the power supply transistor to be made shallow, thereby reducing the voltage applied to the plunger.