JPH0130750Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a processing circuit that employs a mechanical contact type switch as a signal input source.

In general, mechanical contact type switches have the disadvantage that their operation becomes unstable unless a large current flows beyond a certain level, in case a film forms on the contacts. On the other hand, if the input signal is given by a mechanical contact switch, the constant voltage circuit must have a large current capacity, and in reality there is no need to provide such a large constant voltage circuit in the processing circuit. Well then,
Currently, mechanical contact type switches are not normally used.

The present invention was devised in view of this problem, and when a mechanical contact type switch is used as an input signal source, stable operation can be achieved using a mechanical contact type switch without using a constant voltage circuit with a large current capacity. The basic objective is to provide a connection structure for a mechanical contact type switch that can guarantee the switch and ensure good operation of the processing circuit.

Therefore, in the present invention, a mechanical contact type switch as a signal input source of the processing circuit is connected to a constant voltage circuit that is the power supply of the processing circuit, and at the same time, the constant voltage circuit is connected to the power supply side of the constant voltage circuit itself. The basic feature is that a large current can be passed through a mechanical contact type switch without placing a large burden on the switch.

Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiments.

In the drawing, 1 is a processing circuit having two terminals 1a and 1b as input terminals, 2 is a constant voltage circuit that provides a stabilized constant voltage to the processing circuit, and this constant voltage circuit connects its output line 2a to the processing circuit. 1
and to two mechanical contact type switches 3 and 4 provided for signal input via resistors 5 and 5' and protective diodes 6 and 6', respectively.

The input terminals 1a and 1b of the processing circuit 1 are connected to the resistors 5 and 5' and the protective diodes 6 and 1b, respectively.
6', and when the mechanical contact switch 3 is turned on, the voltage of the input terminal 1b is lowered, and when the mechanical contact switch 4 is turned on, the voltage of the input terminal 1b is reduced.
The voltage at the input terminal 1a is lowered, and the voltage drop is used as a signal input to perform predetermined data processing.

In this embodiment, the resistance values of the resistors 5 and 5' are increased to minimize the amount of current flowing through the resistors 5 and 5'.
When the switches 3 and 4 are turned on, the voltage of the output line 2a of the constant voltage circuit 2 is prevented from decreasing.
Therefore, the amount of current flowing from the output line 2a of the constant voltage circuit 2 through the resistors 5, 5' and the diodes 6, 6' is very small, and the amount of current flowing through the mechanical contact type switches 3, 4 is very small.
Since there is a risk that the switch will not operate reliably even if the switch is turned on, each mechanical contact type switch is connected to a protective resistor 8, 7' by another power supply line 7, 7', as shown in the figure.
8' to the power supply 9 of the constant voltage circuit 2, and when the mechanical contact switches 3 and 4 are turned on, a current is simultaneously supplied to the output side of the constant voltage circuit and from the power supply 9 of the constant voltage circuit. By supplying the signal to the contact type switch, a stable input signal is provided to the processing circuit without causing fluctuations in the output voltage of the constant voltage circuit. Therefore, the protective resistors 8 and 8' are connected to the mechanical contact type switches 3 and 8'.
The resistance value is set to be small so that sufficient current can be supplied for stable operation of 4.

As is clear from the above explanation, the present invention provides an input signal to a processing circuit powered by a constant voltage circuit using a mechanical contact type switch, and when the mechanical contact type switch is turned on, , ensuring stable operation by supplying current not only from the output side of the constant voltage circuit but also from the power source of the constant voltage circuit through the protective resistor, allowing a relatively large current to flow through the mechanical contact switch. The present invention provides a connection structure for a mechanical contact type switch characterized by the following features.

Therefore, according to the present invention, even if the amount of current flowing from the output line of the constant voltage circuit to the mechanical contact type switch is reduced, the mechanical contact type switch receives sufficient current from the power supply of the constant voltage circuit via the protective resistor. Mechanical contact type switches can operate stably because a certain amount of current flows through them.

In addition, since the amount of current flowing from the output line of the constant voltage circuit to the mechanical contact type switch is reduced,
The voltage of the output line will not drop, will not affect the processing circuit and cause it to malfunction, and will not affect other circuits using the output line.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing the connection structure of the mechanical contact type switch according to the present invention. 1... Processing circuit, 1a, 1b... Input signal terminal, 2... Constant voltage circuit, 2a... Output line,
3, 4... Mechanical contact switch, 5, 5'... Resistor, 6, 6'... Protection diode, 7, 7'...
Connection line, 8, 8'...Resistor, 9...Power supply for constant voltage circuit.

Claims (1)

[Scope of utility model registration request] A mechanical contact type switch is connected via a resistor and a diode to the output line of a constant voltage circuit that supplies a stabilized voltage to a processing circuit equipped with at least one signal input terminal, and a The input terminal is connected between the above resistor and the diode, and a signal is input to the signal input terminal by turning on and off the mechanical contact switch.
A current that is sufficiently larger than the current supplied from the output line side of the constant voltage circuit when the mechanical contact switch is turned on is applied between the diode side contact of the mechanical contact switch and the input power source of the constant voltage circuit. A protective resistor for the on/off operation of the contact is supplied from the input power supply side of the voltage circuit to the contact of the mechanical contact switch to ensure its on operation, and the current taken out from the constant voltage circuit when the mechanical contact switch is turned on is connected. A connection structure for a mechanical contact type switch characterized by suppressing fluctuations in the output voltage of a constant voltage circuit due to sudden changes in the voltage.