JPS5830300Y2 - Low voltage power on/off device for small electronic equipment - Google Patents

Description

[Detailed description of the invention] This invention is a small electronic device that turns on and off the power supply from the power source to the load by mechanically operating the normally open contact in small electronic devices such as magnetic sheet type recorders and playback machines. This invention relates to a low-voltage power supply on/off device for equipment.

A small magnetic card recording/playback machine presses the start switch to keep the motor, recording/playback amplifier, pilot lamp, etc. in an on state, and the motor rotates the turntable to record on or play back the magnetic card. When the rotation speed reaches a predetermined number of revolutions, a stop switch is automatically activated and the load is turned off.

Since the main purpose of small magnetic sheet type recording and playback devices is generally as small personal learning devices, it is convenient to use batteries as the main power source for convenience of use. The actual situation is that the power supply voltage is 2.5 to 3.5 square meters, and the power capacity is also limited.

Therefore, it is very important to minimize the power consumption during non-operation and to lower the operating voltage.

In order to solve this problem, attempts have been made to replace the conventional operation control switch mechanism using relays and the like with electronic circuits using transistors, SCRs, and the like.

Examples thereof are shown in FIGS. 1 and 2.

The electric hold switch in Fig.
It is a combination of a switching transistor TR and a switching transistor TR, and utilizes the holding function of flip-flops F and F.

However, in order to keep the switching transistor TR in the on state, it is necessary to supply current to the flip-flops F and F, which are holding function elements, resulting in power loss.

Furthermore, if the holding function element is formed of a flip-flop, an initial reset is required, which causes the problem that the entire circuit becomes complicated.

This was devised to eliminate the complexity of the entire circuit that occurs when flip-flops are used as holding function elements.
This is the electrical hold switch shown in FIG.

That is, the self-holding function of the SCR is used instead of configuring the holding function element with a flip foot.

This electrical holding switch circuit includes a stop switch S2 consisting of a normally closed contact switch, a start switch S2 consisting of a normally open contact switch, SC'R as a self-holding functional element, a switching transistor TR1, a protective resistor R1, R2 and R3.

Briefly explaining the operation of this circuit, when the start switch S2 is pressed, a pulsed current flows through the gate of the SCR, turning on the SCR.

Therefore, the switching transistor TR1 becomes conductive, and power is supplied to the load.

Next, when the stop switch S1 is pressed, the current between the emitter and the base of the switching transistor TR1 is cut off, so that the SCR is turned off, and therefore the switching transistor TRI becomes non-conductive.

However, since the stop switch S1 is configured with a normally closed contact switch, it has low reliability.
1 becomes open, the SCR is turned off and the switching transistor TR1 is held in a non-conductive state, causing a problem in that the operation of the device stops midway.

The purpose of this invention is to achieve the above-mentioned effect by configuring both the start switch and stop switch in the operation control switch circuit of a low-voltage power supply on/off device for small electronic equipment, such as a magnetic sheet type recorder/player, as normally open contact switches. An object of the present invention is to provide a power on/off device that solves the problem.

FIG. 3 is an electrical circuit diagram for explaining one embodiment of this invention. As shown in the figure, the emitter-collector circuit of a PNP transistor TR2 that controls on/off the load is connected in series with the load. The emitter-collector circuit of a PNP transistor TR3 functioning as a self-holding function element is connected to the base of the transistor TR2 through a base current limiting resistor R4.

The base of this transistor TR3 is connected to the collector side, that is, the load side, of the transistor TR2 through a resistor R5, and the normally open contact switch S3 for starting and the NPN
) It is connected to the negative potential side of the power supply E through a parallel circuit with the collector-emitter circuit of the transistor TR4.

Further, the collector of the transistor TR3 is connected to the base of the transistor TR4, and the base of the transistor TR4 is connected to the negative potential side of the power source E through a resistor R6 and a normally open stop contact switch S4.

In the circuit shown in FIG. 3, now the transistor T
If R4 is non-conductive, transistors TR3 and TR2 are also non-conductive and no power is supplied to the load.

In this state, when the normally open contact switch S3 for starting is instantaneously closed, the transistor TR3 becomes conductive, the transistor TR2 becomes conductive, and power is supplied to the load.

After that, the switch S3 is opened and the transistor TR
A bias voltage is supplied to the base of the transistor TR4 by the resistor R6, and the transistor TR4 becomes conductive, so that the transistor T R3j T R2 continues to conduct, and power continues to be supplied to the load.

In this way, when power is supplied to the load and, for example, the turntable rotates a predetermined number of times and the stop switch S4 consisting of a normally open contact is turned on, the base-emitter of the transistor TR4 is turned on. The transistor TR4 is short-circuited and becomes non-conductive, so that the transistor TR3
And TR2 becomes non-conductive, cutting off the current to the load.

As is clear from the above description, according to the present invention, when the switching transistor TR2 is in a non-conducting state, no power is consumed other than the dark current of the switching transistor TR2, and the operating power supply The voltage is the base-emitter voltage of the switching transistor TR2 and the self-holding transistor T R3t T R
It is sufficient if the voltage is higher than the sum of the saturation voltage of 4, so 2■
It is enough.

Furthermore, since both the start switch and stop switch are normally open contact switches, that is, instantaneous closing switches, reliability during equipment operation is improved, and since normally open contact switches can be used, switches with small switching capacity can be used. Therefore, there are effects such as being able to reduce the size of the device.

[Brief explanation of the drawing]

1 and 2 are diagrams showing a conventional example of a switch circuit for operation control, and FIG. 3 is an electrical circuit diagram for explaining an embodiment of this invention. E...power supply, L...load, TR2...switching transistor for load control, TR3, T'R4...transistor for self-holding, S3...normally open contact switch for starting, S4... Normally open contact switch for stop.

Claims (1)

[Claims for Utility Model Registration] A switching transistor TR2 in which a load that generates the function of a quantum device is connected in series to an emitter-collector circuit, and power is supplied to a series circuit of the load and the switching transistor TR2. a resistor R4 whose one end is connected to the base of the transistor TR2, an emitter-collector circuit of the transistor TR3, and one end of which is connected to the connection point between one pole of the power supply E and the load. A series circuit consisting of a resistor R6, a resistor R5 connected in parallel with the load, and a transistor T whose emitter side is connected to one pole of the power supply E.
a series circuit consisting of a collector-emitter circuit of R4; and a start circuit connected between the connection point of the base of the transistor TR3 and the collector of the transistor TR4 and one pole of the power source E for driving the load. a normally open contact switch S3, a stop switch connected between the connection point of the collector of the transistor T'R3 and the base of the transistor TR4, and one pole of the power source E, for canceling the drive of the load; Normally open contact switch S
4. A low voltage power supply on/off device for small electronic equipment, characterized by comprising the following.