JPS63211418A - Key input device - Google Patents

Abstract

PURPOSE:To simplify the maintenance work by converting the analog voltage of a value corresponding to a resistance value of a variable resistance circuit, to a digital signal. CONSTITUTION:When one of key switches SW1-SW7 is depressed, the resistance value of a variable resistance circuit 1 is varied to a value corresponding to its key switches SW1-SW7, and the analog voltage from a voltage generating part RB becomes a value corresponding to its key switches SW1-SW7. This analog voltage is converted to a digital signal by an A/D converting part 5, it is discriminated by a control part, etc., through an input, etc., and the depressed switches SW1-SW7 are recognized. In such a way, the number of signal lines between the key switch side and the body side, and terminals can be decreased, and the generation rate of a fault due to a contact failure and a disconnection, etc., is reduced, and the mounting and maintenance can easily be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a key manual device for inputting information into various electronic devices such as computers and computer-applied devices.

(Prior Art and its Problems) In electronic devices such as computers and computer-applied devices, key-operated devices consisting of a large number of key switches are used to input information.

The simplest configuration of a key power device is to connect each terminal of a large number of key switches to the input port of the main body of the electronic device with an independent signal line, and to transmit the signal from each key switch to the input port individually. That's true. However, with this configuration, the number of signal lines connecting the keyboard or operation panel to which the key switch is installed and the main unit that has the input port increases in proportion to the number of key switches, which increases the number of terminals and connectors. As the number of poles increases, the incidence of failures due to poor contact and wire breakage increases, and this significantly impedes the simplification of wiring mounting design and work, as well as maintenance work, and the trend is particularly towards miniaturization or integration. This has had the problem of hindering the miniaturization of electronic devices.

In order to solve this problem, a key-powered device described in Japanese Patent Publication No. 53-20331 was proposed. This is a system in which two groups of signal lines are arranged in a matrix, and a key switch is connected to each intersection of the two groups. With this configuration, the number of signal lines between the keyboard and the main body is considerably reduced. , but for example, for 30 keyswitches, there are still 11
This method requires multiple signal lines and has the disadvantage that the control circuit for identifying each key switch is also complicated.

(Means for Solving the Problems) The present invention solves the above-mentioned problems, and the present invention is capable of significantly reducing the number of signal lines and terminals between the key switch side and the main body side. The purpose is to provide equipment;
The technical means includes a variable resistance circuit consisting of a plurality of key switches and a plurality of resistance elements connected to these key switches, and a voltage generation section that generates an analog voltage of a value corresponding to the resistance value of the variable resistance circuit. , and an AD conversion section that converts the analog voltage from the voltage generation section into a digital signal.

(Function) When any key switch is pressed; the resistance value of the variable resistance circuit changes to a value corresponding to that key switch, and the analog voltage from the voltage generator becomes a value corresponding to that key switch. This analog voltage is converted into a digital signal by an AD converter, and this is discriminated by a controller or the like via an input port or the like, and the pressed key switch is recognized.

(Example) Embodiments of the present invention will be described below based on the drawings.

In the figure, a keyboard K includes many key switches S.
WI to SW7, and each of these key switches SWI to S
Resistors R1-R7 are connected in series to W7, and each key switch SWI-SW7 and each resistor R
The series-connected bodies 1 to R7 are connected in parallel with each other to form a variable resistance circuit l whose outputs are terminals 2.3 at both ends.

The main body M has a constant voltage terminal 4 connected to a constant voltage power supply VC.
, a reference resistor RB for generating an analog voltage VA having a value corresponding to the resistance value of the variable resistance circuit 1 according to a voltage division ratio with the resistance value RA of the variable resistance circuit 1, and an AD converter for converting the analog voltage VA into a digital signal. 5, and a control section 6 consisting of a microcomputer or the like having a human-powered boat.

Here, assuming that the resolution of the AD converter 5 is 3 bits,
It is assumed that the reference voltage VREF (equal to the voltage of the constant voltage power supply VC) is 5V, and that the input voltage VIN and output data have the relationship shown in Table 1. The value in parentheses in the input voltage section of Table 1 is the median value.

The value of the reference resistance RB in Table 1 is 100Ω, and each key switch SW
If the values of the resistors R1 to R7 are set so that when I to SW7 are pressed, the analog voltage ■A becomes equal to the median value of the input voltage VrN, the values shown in Table 2 will be obtained.

Table 2 Then, the analog voltage VA generated by the pressed key switch among the key switches SWI to SW7 is
The output data DO to D2 after being converted into digital signals by the AD converter 5 are as shown in Table 3.

Table 3 This output data DO-D2 is input to the control unit 6, which of the pressed key switches SW1-SW7 is recognized, and the control unit processes the signal or information accordingly. can.

In the above embodiment, the keyboard and the main body M are two parts.
Connected by only one signal line, the number of signal lines and terminals is greatly reduced. Therefore, the connectors used to connect these devices should have a small number of pins (the incidence of failure due to poor contact or disconnection is low, it is easy to implement and maintain, and the equipment can be made smaller).

In the above-described embodiment, when increasing the number of key switches, the resolution (bit number) of the AD converter 5 may be increased, and the resistors R1 to R7 may be increased and set to appropriate values. Generally, if the number of bits of the AD converter 5 is n, the number N of distinguishable key switches is N=2'
-1.

For example, if an AD converter with a resolution of 6 bits is used, 6
Three key switches can be distinguished. Even in this case, the number of signal lines may be two. However, there may be additional signal lines for ground lines, indicator lights, and other special switches.

In the above embodiment, each key switch 3W1 to SW
7 and each of the resistors R1 to R7 are respectively connected in series. A variable resistance circuit connected in series with one end of the resistors R1 to R7 connected in series, and one end of each resistor R1 to R7 connected in series.
A variable resistance circuit connected to the connecting portion of R7 so as to be short-circuited by key switches SW1 to SW7 may be used. The reference resistor RB may be provided on the side of the constant voltage voltage avC. For the AD converter 5, for example, a microcomputer may be used as a control section, and an AD converter built into the microcomputer may be used.

(Effects of the Invention) According to the present invention, the number of signal lines and terminals between the key switch side and the main body side can be significantly reduced, the occurrence of failures due to poor contact or disconnection is low, and Also, maintenance becomes easier, and the equipment can be made smaller.

[Brief explanation of the drawing]

The drawing is a circuit diagram of a key manpower device according to an embodiment of the present invention. SWI~SW7...Key switch, R1~R7...
Resistor (resistance element), RB...Reference resistance (voltage generator), ■...Variable resistance circuit, 5...AD converter (AD
conversion part).

Claims (1)

[Claims] A variable resistance circuit consisting of a plurality of key switches and a plurality of resistance elements connected to these key switches, a voltage generation section that generates an analog voltage of a value corresponding to the resistance value of the variable resistance circuit, and a voltage generation section from the voltage generation section. A key input device comprising: an AD converter that converts an analog voltage into a digital signal.