JPH02112316A - Transistor switch - Google Patents

Abstract

PURPOSE:To reduce the cost of general-use transistor(TR) switch by providing both over current restricting function and timer switch function at an output TR. CONSTITUTION:The current restricting function to cope with an A-type load is applied to a TR 11, and the same output TR 11 is used for the timer switch function to operate by the over current. As a result, the TR can be reduced, simultaneously a specially deviated large heat radiating plate for output TR protection can be eliminated, and as a matter of fact, on output TR protecting fuse is made unnecessary. Further, at the TR switch shown in a figure, since the current disconnected due to the over current is made into an over current condition again by the reopening/reclosing of a TR switch control switch 1, replacing components like the fuse is unnecessary even when a short-circuit accident is generated. Thus, the mass production of the generally applicable TR switch is attained, and the costs can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a contactless electrical switch using a transistor (hereinafter abbreviated as "transistor switch").

Traditionally, transistor switches have been extremely durable and reliable compared to contact type switches and electromagnetic relay switches when used with an appropriate load current.

However, in the case of loads such as motor loads or incandescent lamps that flow a large current at the beginning of operation (hereinafter referred to as Δ-type loads), unless a special large-capacity Hatake Cadran Sister is used, they may be damaged instantly or are extremely durable. A transistor switch with no characteristics. Conventional transistor switches that can handle type A loads require an extra large capacity output transistor and are very expensive. Figure 1 shows an example of the wiring diagram. Another method is to provide a current limiting function in the output quadrant sister and use a normal transistor to handle the △ type load, but this method generates a special amount of heat in the output quadrant sister when the load circuit is shorted. A large heat sink is required, making the device extremely large, and the fuse does not operate and cannot be used because the load circuit has such a current limit. Figure 2 shows an example of the wiring diagram. As explained above, in order to complete a general-purpose transistor switch that can be used with any load without being damaged, the only way to create a conventional transistor switch is to combine an extra-large capacity output transistor switch with a heather, or to combine it with an extra-large heat sink and a current limiter. Because of the lack of Naturally, general-purpose transistor switches that could be used without any special load restrictions were few in number and expensive, so they did not become popular.

As a result, transistor switches for general use, which could not be mass-produced, were naturally expensive.

The present invention is an attempt to solve the various problems mentioned above and to reduce the price of a general-purpose transistor switch.

To illustrate an embodiment of the present invention and explain its operation, Fig. 1 shows an embodiment of a conventional transistor switch. Use a large-capacity output run sister that can withstand current sufficiently and will not be damaged. Simultaneous C: A fuse is used as the output run sister protection device t (hereinafter abbreviated as "protection 1!il"). In the figure (1)
is a switch for controlling a transistor switch, (3) is a power supply, 6) is a small transistor for controlling an output run sister, and (7) is a resistance.

Figure 2 shows the miniaturization of the output run sister (8) by a total of 9 mainly due to the effects of the resistor (9) and Zener diode (10).
It has a configuration that can adequately handle the mold load. Then, a large amount of heat generated in the event of a short-circuit accident in the load (2) is removed using an extra large heat sink of the quad run sister (8). J! It is used as a protection against losses (4). However, the disadvantage is that the external size is large and the output run sister may be damaged if the short circuit continues for too long. In the figure, (1) is a switch for controlling a transistor switch, (3) is a power supply, 6) is a small transistor for controlling an output run sister, and (7) is a resistor.

Part 3 shows an embodiment of the present invention, in which the output run sister (11) is provided with a current limiting function that can handle a square load, and at the same time, the same output run sister (11) is provided with a timer that operates due to overcurrent. It is configured to also function as a switch. At the same time as reducing the size of the quadratic sister, an extra large heat sink for protecting the output quadrant sister cannot be omitted, and of course, a fuse for protecting the output quadrant sister is also unnecessary. In addition, in the transistor switch of the illustrated embodiment, the current cut off due to overcurrent is turned on again by reopening and closing the transistor switch control switch (1), so even if a short-circuit accident occurs, there are no parts such as fuses that need to be replaced. Since it is not necessary, it is a very good way to protect the Ikadran Sisters. The control switch (1) of the transistor switch is not particularly limited, and any suitable switch can of course be selected. In order to commercialize transistor switches in large quantities, it was very important to not only have a low price, but also to be able to choose the type of load, and to avoid failures even if the load was short-circuited.However, this invention overcomes the various problems mentioned above. This solution also enables mass production of general-purpose transistor switches and lowers prices. Note that (2) in the figure shows the load of the transistor switch, and 3) is the power supply (9) (12) (14)
The symbol (7) is a resistor, (13) is a capacitor for the timer switch, (10) is a Zener diode, (6), and the symbol (15) is an NP/L-type small transistor. is PNP
Show type. The part surrounded by the dotted line in (4) is mainly the parts related to the timer switch configuration.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram of a conventional transistor switch, and is an example in which a large transistor is used for a Δ-type load and a fuse is used as a protection device. Use current limit to maintain the current limit for the curved load! This is an example in which a large heat sink is used as the device. FIG. 3 is a wiring diagram showing an embodiment of the present invention in which the output run sister has current limiting and timer switch functions.

Claims (1)

[Claims] A transistor switch characterized by having an output transistor with both an overcurrent limiting function and a timer switch function.