JPS6382017A - Information input device - Google Patents

Abstract

PURPOSE:To hold the load on an interface power source nearly constant even if the number of inputs of contact information becomes extremely large by providing a switching circuit which controls the supply of the interface power source optionally. CONSTITUTION:The switching circuit 4 controls the supply of the interface power source to respective photocouplers 11 - 1n with a control signal. A photocoupler 6 is turned on with the control signal and then a transistor 5 turns off, so that none of the respective photocouplers 11 - 1n is powered on. Therefore, the photocouplers are powered on only when necessary and no power source is supplied in other cases. Consequently, the load on the interface power source is held nearly constant even if the number of pieces of contact information increases greatly, and the power source capacity can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an information input device, and more particularly to an information input device that inputs a plurality of contact information from the outside while electrically insulating the information using a photocoupler.

[X and I Information processing equipment is provided with an interface to input information from the outside, and an example of this interface is to input multiple contact information from the outside by electrically insulating the input and output of the interface. There is a method that uses a photocoupler for input.

An example of a circuit using such a system is shown in FIG.
By electrically shorting each of the input terminals 1 to 1n to the negative side of the device power supply, each photocoupler is turned on and electrical continuity is established between a pair of output terminals of each photocoupler. It is something. Note that 21 to 2n are current limiting resistors, and each of the photocouplers 11 to 1n is connected to the positive side of the device power supply through the current limiting resistors 21 to 2n, respectively, and is supplied with operating power.

In this configuration, when the external input contact 3 shown by the dotted line is in the closed state, current is supplied to the photocoupler 11 via the resistor 21 and the closed contact 3, so the photocoupler 11 is turned on. , contact open information is generated at the output of the pair.

The same applies to other photocouplers.

In the conventional photocoupler isolated information input circuit described above,
When a contact that inputs contact information from the outside is in a closed state, an interface current constantly flows. Therefore, as the number of input information increases, the capacity of the interface power supply increases, and it is necessary to determine the power supply capacity a by considering the number of input signals.

OBJECTS OF THE INVENTION An object of the present invention is to provide an information input device that can maintain a substantially constant load on an interface power supply even when the number of input information becomes extremely large, and does not require an increase in its capacity. That's true.

According to the present invention, there is provided an information input device for inputting a plurality of contact information from the outside while electrically insulating the information using a photocoupler, and in which the operating power source of the photocoupler can be freely controlled on and off. There is obtained an information input device characterized in that a switching circuit is provided and the operating power source is controlled to be turned off except when waiting for input of the contact information.

1l3 The present invention will be described in detail below using the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention, and parts equivalent to those in FIG. 2 are designated by the same reference numerals. In this example, a switching circuit 4 for power on/off control is provided between the current limiting resistors 21 to 2n of each of the photocouplers 11 to 1n and the positive side of the interface power supply. Is this switching circuit 4 an interface? The supply of lWI to each of the photocouplers 11 to 1n is controlled by a control signal.

The switching circuit 4 includes a switching transistor 5, a photocoupler 6 for on/off control of the transistor 5, and a base bias resistor 7 for the transistor 5. When this photocoupler 6 is turned on by a control signal, the transistor 5 is turned off and no operating power is supplied to each of the photocouplers 11 to 1n. Therefore, it is possible to supply power to the photocouplers 11 to 1n only when necessary, and not to the others.

Therefore, by providing an interface power on/off switching circuit 4 for each unit of information (a collection of information such as 8 bits or 16 bits that needs to be input at one time), the interface power can be turned on immediately before inputting the information. It is possible to freely perform control such as supplying power and cutting off the power supply after inputting information. Therefore, the load on the interface power supply has a very large number of input information (even if
This makes it possible to maintain a substantially constant value and also to reduce the power supply capacity.

Here, a photocoupler 6 is used to control on/off of the switching transistor 5, and this is to electrically isolate a control signal for turning on/off the power from inside the device from the power supply side.

This is because the input section for external contact information is electrically insulated, so even if the switching circuit 4 is added, this insulation still needs to be guaranteed.

As described above, according to the present invention, by providing a switching circuit that can arbitrarily control the supply of interface power, even if the number of input contact information becomes extremely large, the load on the interface power supply can be reduced to almost nothing. It has the advantage that it can be maintained constant and the power supply capacity can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional information input device. Explanation of symbols of main parts

Claims (2)

[Claims] (1) An information input device that inputs a plurality of contact information from the outside while being electrically isolated using a photocoupler, which is provided with a switching circuit that can freely control on/off the operating power of the photocoupler, and the contact information An information input device characterized in that the operating power source is controlled to be turned off except when inputting. (2) The information input device according to claim 1, wherein the switching circuit is configured to input an on/off control signal to a switching element via a photocoupler.