JPH046977B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a push-button switch input circuit for detecting the position on a matrix of a press-connected push-button switch in an input device using a matrix switch.

Conventionally, as a method for detecting the change of a large number of switches from an open state to a closed state, the number of input signal lines is saved by arranging the switches in a matrix, such as switches installed on a keyboard device or an operation desk. Conventionally, the input circuit for this purpose has generally been constructed as shown in FIG.

In other words, 1 is a matrix switch, but its
The axis signal lines x ₁ , x ₂ , . . . are connected to the timing signal generation circuit 2, and the Y-axis signal lines y ₁ , y ₂ , . sequentially sends timing pulses to each X-axis signal line x ₁ , x ₂ , . . . as shown in FIG.

Now, when any one of the matrix switches is pressed and connected, the timing pulse is transmitted to any of the corresponding Y-axis signal lines y ₁ , y ₂ , . . . through the pressed switch, and the latch circuit 3 and its output terminal a ₁ ,
Since it appears as a digital signal in either _{a 2} , . . . , the position of the pressed switch on the matrix can be identified by processing this data.

However, in the conventional circuit shown in FIG. 1, at least one timing pulse needs to be sent while the push button switch is pressed, so one period T of the timing pulse sent to each X-axis signal line is The timing circuit 2 must be set short, and if there are many push button switches, the timing circuit 2
Moreover, the latch circuit 3 is required to be extremely high-speed, making it complicated and expensive.

The present invention has been made in order to eliminate the drawbacks of the conventional push button switch input circuit as described above, and the present invention is to connect each of the X-axis and Y-axis signal lines to light emitting elements of the first and second photo coupler groups, respectively. A signal generated at the output of the light-receiving element by the current flowing therein is inputted to each input terminal of the data register, and also connected to the light-emitting element of the second photo coupler group, and a current flowing therethrough. The signals generated at the outputs of the light receiving elements are input to each input terminal of the data register, respectively, and a trigger photo is connected in series with the second photo coupler group so that all the current flowing through the photo coupler group passes through.・Providing a push button switch input circuit in which a coupler is connected and the output of the light receiving element is inputted to the set input terminal of the data register with a required delay through a latch pulse generator and a delay circuit. purpose.

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 3 is a circuit diagram showing an embodiment of the push button switch input device according to the present invention.

In this figure, 1 is a matrix switch circuit, and there are push buttons S at the intersections of the X-axis signal lines x ₁ , x ₂ , ... x _n and the Y-axis signal lines y ₁ , y ₂ , ... y _o , respectively. _X -axis signal lines x ₁ to x _o are connected to the cathodes of photo diodes 401 to 40 m of each photo coupler 41 to 4 m in the first photo coupler group 4 _, and the anode side are supplied with power through protective resistors 51 to 5m, and the photocoupler outputs generated in phototransistors 411 to 41m paired with these photodiodes are input to predetermined input terminals D ₄₁ , D ₄₂ , . . . of the data register, respectively. ..., D ₄ m.

On the other hand, the Y-axis signal lines y ₁ to y _o are connected to the anodes of the photo diodes 701 to 70n constituting the second photo coupler group 7, respectively, and the cathodes are concentrated at one point to the trigger photo coupler 8. The output terminals of the photo transistors 711 to 71n paired with the photo diode of the second photo coupler group 5 are respectively connected to the anode of the photo diode 801 and its cathode side is grounded. Connect to input terminals D ₇₁ to D _7o . Further, the output of a phototransistor 811 paired with the trigger photocoupler 8 is connected to a latch pulse generating circuit 9, and this output is connected to the set signal input terminal of the data register 6 via a delay circuit 10.

The push button switch input device of the present invention constructed as described above operates as follows. Now, if switch S ₁₁ of matrix switch group 1 is pressed,
The photodiode 401, the X-axis line _x1 , the switch _s11 , the Y-axis line _y1 , and the photodiode 70 are connected to the photodiode 401 by the power supply +V supplied through the protective resistor 51.
While the switch s ₁₁ is pressed, a current i as shown in FIG. As a result, the phototransistors 411, 711 and 811 inside the photo couplers _{41, 71} and ₈ become conductive at the timing shown in FIG. It becomes electric potential. On the other hand, the latch pulse generating circuit 10 generates a latch pulse by receiving the output of the trigger photo coupler 8, and this signal is processed by the delay circuit 10 in the next stage with a required delay time t as shown in FIG. 4c. The signal reaches the set signal input terminal s of the data register 6.

The data register 6 then performs the necessary logical operations on the three types of signals and inputs them to the input terminals _D41 and
Output O ₄₁ and corresponding to the ground potential signal of D ₇₁
A high potential as shown in FIG. 4d is output to O ₇₁ , and low potential is output to other output terminals O ₄₂ to O _4o and O ₇₂ to O _7o .

By processing the digital signal at the output terminal of the data register 6 obtained in this way using, for example, a microcomputer, it is possible to identify that the pressed switch is _s11 .

Since the present invention is configured and operates as described above, it does not require an expensive high-speed timing pulse generation circuit as in conventional push button switch input devices, and the switch pressing operation is not limited to the period thereof. Accurate operation can always be expected regardless of the operating proficiency of the operator, and since signals are sent and received via a photocoupler, it also has the effect of preventing malfunctions due to noise.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional push button switch input circuit, FIG. 2 is a timing chart showing its operation, FIG. 3 is a block diagram showing an embodiment of the push button switch input circuit according to the present invention, and FIG. Figures a to d are timing charts illustrating the operation of each part. 1...Matrix switch circuit, _s11 to s _on
...Push button switch, x ₁ to x _n ...X axis signal line,
y ₁ to y _o ...Y-axis signal lines, 4 and 7...First and second photocoupler groups, 401 to 40m and 7
01 to 70n...photocoupler light emitting element, 4
11 to 41m and 711 to 71n...Photocoupler light receiving element, 6...Data register, 8
...Trigger photo coupler, 801... Light emitting element of trigger photo coupler, 811... Light receiving element of trigger photo coupler, 9... Latch pulse generator, 10... Delay circuit.

Claims (1)

[Claims] 1. In a matrix switch input circuit in which switches are arranged at the intersections of a large number of X-axis signal lines and Y-axis signal lines, each of the X-axis and Y-axis signal lines is connected to a first and a second photo coupler, respectively. connected to the light emitting elements of the group and said first and second photo-diodes.
The light receiving element output of each coupler group is configured to be inputted to a predetermined input terminal of a data register, and the light emitting element of the trigger photo coupler is connected in series with the light emitting element of the second photo coupler group. By inputting the light receiving element output to the set input terminal of the data register via a latch pulse generator and a delay circuit, a signal appears at the input terminals of the data register corresponding to the X-axis and Y-axis signal lines, respectively. and a signal appearing at the set input terminal to detect which of the matrix switches has transitioned from an open state to a closed state.