JPH0795643A - Button depression information recognition circuit for key telephone system - Google Patents

Abstract

PURPOSE:To allow the telephone system to cope with increase in key switches by dividing the circuit such that a key switch under an optical button is closed when the optical button is depressed, a predetermined analog voltage is produced, the voltage is converted into a digital voltage and corresponding button depression information is recognized to facilitate the software control. CONSTITUTION:Key switches S1-Sn-1 corresponding to connecting points of resistive elements R1-Rn divide respectively a power supply voltage and the divided voltage is led to an A/D converter 1. When, e.g. a button (i) of a key telephone system is depressed, the key switch S1 under the button (i) is closed, an analog voltage {(n-i)/n}V is led to the A/D converter 1, in which the voltage is converted into an analog voltage and it is fed to a button depression information recognition section 2. The recognition section 2 refers to the stored table to recognize which button is depressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a button press information recognizing circuit for a button telephone which identifies button press information from a button pressing operation on the button telephone.

[0002]

2. Description of the Related Art In a conventional button telephone, a plurality of output ports and a plurality of input ports are arranged in a matrix, and each intersection of this matrix is connected through a key switch arranged to press a button. The button press information is recognized by software by detecting which input port the pulse output output to a specific output port returns to by the microcomputer.

However, in the above-mentioned button press information recognizing circuit of the key telephone, it is very difficult to control the software, and it is easy to cause a trouble. In particular, when the number of key switches is large, it is more likely that trouble will occur.

In addition to this, the pulse output output to the output port is often mixed in the high gain analog amplifier circuit and converted into an audible signal as noise. Further, when it is actually realized in a button telephone, there is a drawback that the pattern amount becomes very large.

[0005]

As described above, since the conventional button press information recognition circuit of the button telephone adopts the pulse detection system by the matrix wiring,
Software control is very difficult, and problems often occur when the number of key switches is large. In addition, the pulse output output to the output port is often mixed with a high gain analog amplifier circuit and converted into an audible signal as noise. Further, it has a drawback that the pattern amount becomes very large.

The present invention has been made in order to solve the above-mentioned problems. It is easy to control software, can easily cope with an increase in the number of key switches, and has no influence on peripheral circuits. The purpose is to provide a circuit.

[0007]

To achieve the above object, a button press information recognition circuit of a button telephone according to the present invention comprises a plurality of resistance elements connected in series between a reference potential and a zero potential. One end is connected to the connection point between each element of the plurality of resistance elements, and it is arranged to press the button of the button telephone and is turned on by pressing the button. An analog / digital conversion unit that converts each derived voltage into a digital value, and a button press information recognition unit that recognizes corresponding button press information from the digital value obtained by the analog / digital conversion unit are provided. It is characterized by having done.

[0008]

In the button press information recognizing circuit of the button telephone having the above configuration, when an arbitrary button is pressed, the key switch arranged below the key switch is turned on to derive a predetermined analog voltage. This analog voltage is converted into a digital value, and the corresponding button press information is recognized from this digital value.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIG.

FIG. 1 shows the configuration of a button press information recognition circuit of a key telephone according to the present invention, in which n resistance elements R1 to Rn having the same resistance value between a power supply voltage V and a ground potential are connected in series. It is connected to the. Each resistance element R1
Key switches S1 to S at connection points between Rn and Rn, respectively.
One end of n-1 is connected.

Each of these key switches S1 to Sn-1 is arranged for pressing a button of a button telephone, and is turned on by pressing the button, and the analog voltage at each connection point is converted into an A / D (analog / digital) converter 1.
Derive to.

The A / D converter 1 converts an analog voltage into a digital value, and the converted digital value is sent to the button pressing information recognition section 2. The button press information recognition unit 2 is realized by a microcomputer and recognizes corresponding button press information from a digital value input by software.

The operation of the above arrangement will be described below.

First, the key switches S1 to Sn-1 corresponding to the connection points of the resistance elements R1 to Rn are respectively supplied with the power supply voltage V.
Is divided and the analog voltage is led to the A / D converter 1.
At this time, the analog voltage and the key switches S1 to Sn-1
The relationship with is {(n-1) / n} V, S when S1 is on.
When 2 is on, {(n-2) / n} V, ..., When Sn-1 is on, (1 / n) V.

For example, a button i (i
When any one of 1 to n-1) is pressed, the key switch Si arranged below is turned on, and the analog voltage {(n-i) / n} V becomes the A / D converter 1 Button press information recognizing unit 2
Sent to.

In the recognition unit 2, the voltage digital values when each button is pressed are stored in a table in advance. When the digital value is input, the table is referred to recognize which button is pressed. This can be easily realized by software using a microcomputer.

Therefore, since the button press information recognizing circuit of the key telephone having the above-mentioned configuration does not adopt the pulse detecting method but uses the analog voltage detecting method, the pulse output is mixed in the high gain analog amplifying circuit. No, there is no problem of affecting the peripheral circuits.

Further, since a predetermined analog voltage is generated in response to each button pressing operation, this is converted into a digital value, and the pressing information is recognized from this digital value, it can be realized by simple software. In particular, if a microcomputer having an A / D conversion function is used, the circuit configuration will be simple and the telephone can be miniaturized.

Needless to say, the present invention is not limited to the above-described embodiments, and can be implemented in various modifications without departing from the gist of the present invention.

[0020]

As described above, according to the present invention, it is possible to provide a button press information recognizing circuit for a button telephone which can easily control software, cope with an increase in the number of key switches, and have no influence on peripheral circuits. be able to.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a configuration of a button press information recognition circuit of a key telephone according to an embodiment of the present invention.

[Explanation of symbols]

 1 A / D converter 2 Button press information recognition unit R1 to Rn Resistance element S1 to Sn-1 Key switch

Claims (2)

[Claims] 1. A plurality of resistance elements connected in series between a reference potential and a zero potential, and one end thereof connected to a connection point between the resistance elements of the plurality of resistance elements, respectively, for pressing a button of a button telephone. A plurality of key switches that are turned on when the button is pressed, an analog / digital converter that converts the voltages respectively derived from the plurality of key switches into digital values, and an analog / digital converter. A button press information recognition circuit of a button telephone, comprising a button press information recognition unit for recognizing corresponding button press information from the obtained digital value. 2. The button press information recognition circuit of the button telephone according to claim 1, wherein the plurality of resistance elements have the same resistance value.