JPS5935226A - Keyboard input circuit - Google Patents

Abstract

PURPOSE:To detect a key selecting point by a simple circuit even when the number of key selection points is large, by connecting resistance groups to longitudinal and lateral conductor lines of a key matrix, and utilizing voltage drops across the resistance the resistance groups due to key operation. CONSTITUTION:The longitudinal and lateral conductors LC1-LCn of the keyboard matrix 20 are connected to the resistor groups VR1, R0-Rn-1, and VR2, and VR'1, R'0-R'n-1, and VR'2, and those resistance groups are connected to a constant voltage +5V and the ground through changeover switches 21 and 22, respectively. When a desired intersection Xii in the matrix 20 is depressed, a divided voltage in the resistance corresponding to the point Xii is A/D-converted 24 through some resistance groups VR'1-VR'2 and the side of the contact (b) of a relay 23 and then supplied to a CPU through an input interface IF25. Then, relays 21-23 are changed over by a relay driving circuit 27 and a divided voltage in the VR'1-VR'2 is A/D-converted 24 through some of the VR1-VR2 and the contact (m) of the relay 23 and inputted to the CPU through the IF25. The CPU discriminates the position of the Xii by those two voltages.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a keyboard input circuit used in a Japanese word processor, etc., and particularly when a key whose key selection point is the intersection of a key matrix date matrix is - This invention relates to a code input circuit.

[Technical background of the invention]

For example, in a Japanese word processor, there are various ways to input kanji information from the keyboard.
There is a method in which a key on which kanji information is printed points to the surface of a single card in some way, thereby inputting information regarding the pointed position. In this case, on the bottom of the keyboard,
As shown in Fig. 1, the conductors 1 are arranged in a matrix, and by pressing on the intersection point of the matrix from the key date surface, the conductor 1 in the vertical and horizontal directions corresponding to this intersection point is
There are things that take advantage of the fact that they come in contact with each other. It is conceivable that a digital circuit such as an encoder may be used as a part of the key for electrically detecting the two conductive wires 1 in contact as an input circuit.

[Problems with background technology]

However, the key matrix node with a very large number of selection points -
If an attempt is made to implement a keyboard input circuit for a computer using a digital circuit as described above, the digital circuit will require a large number of darts and other components, and will be expensive.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a key input circuit that can detect selection points selected by key operation using a simple circuit even if the key matrix has a large number of selection points in some parts. It provides:

[Outline and summary of the invention]

In other words, the key number of the present invention? - The mode input circuit connects a resistor between each conductor in the vertical direction of the key matrix node, and also connects a resistor between each conductor in the horizontal direction,
A constant voltage is applied to both ends of the longitudinal inter-conductor resistance group or the lateral inter-conductor resistance group, and the voltage is applied from one point of the resistance group to which the constant voltage is not applied among the two resistance groups. A switching circuit for deriving voltage is provided, and the switching circuit is switched once during one key operation of the key matrix board, and the voltage is controlled to be derived from the two resistor groups once each during one key operation. The two derived voltages are each subjected to A/D conversion, and processing for detecting a key selection point related to a key operation is performed based on the two converted data.

Therefore, the combination of the voltage level of the vertical conductor and the voltage level of the horizontal conductor is different for each key selection point, and the combination of the two conversion data obtained by condylar A/D conversion of each voltage level is Each key selection point is different, so
It becomes possible to detect key selection points. In this case, one A/
As long as the digital signal corresponding to the key selection points can be obtained from the D converter, the circuit configuration can be simple even when there are many key selection points. [Embodiments of the Invention] The present invention will be explained below with reference to the drawings. An example of this will be described in detail.

In FIG. 2, 20 is an ordinary key date matrix, and a plurality of conductors "R1 to L8" are arranged in the horizontal direction.
n and a plurality of conductors arranged in the vertical direction, 1 to Lc
It has n. The key matrix code is, for example, as shown in FIG. 3, in which a plurality of vertical conductors (for example, metal bars) Lci, etc. are arranged at regular intervals on an insulating substrate 30, and the conductors are arranged between each arrangement. . An insulator 31 is provided so as to slightly protrude from the surface of the first plate. A plurality of horizontal conductors (for example, metal bars) LR1, etc. are arranged at regular intervals on these insulators 31, and an insulator sheet 3 is placed on these conductors Lai, etc.
2 is placed. Therefore, in the above-mentioned key matrix board, the intersection of the vertical and horizontal conductors when viewed from the board surface becomes the key selection point.
Where is the intersection Xii between cj and the horizontal conductor LRt? - It is possible to perform key selection by pressing from the surface blood, bending a part of the conductor Lit in the direction of the gap 33, and bringing it into contact with the conductor Lci.

On the other hand, R1-Rn is a resistor group connected between adjacent conductors of the vertical conductors Lc1 to LCn), and a resistor R
A resistor R6 is connected to one end of the switch 1, and resistors R8l and Rn at both ends are connected to the switching relay contact 21°220 first contact (for example, break contact) through corresponding variable resistors VR1 and VB2. has been done. Also, R1'~
R'-1 is a resistor group connected between adjacent conductors of the horizontal conductors LR1 to LRn, and a resistor R6' is connected to one end of the resistor R1', and a resistor R6' is connected to one end of the resistor R1'; R6
'.

Rrl'-1 corresponds to variable resistors VR,', VR
2' and 6- are connected to the second contact (for example, make contact) side m of the relay contacts 21 and 22. A constant voltage (for example, 5V) is applied to the movable contact C of the relay contact 21, and the movable contact C of the relay contact 22 is grounded. Furthermore, the aforementioned series-connected variable resistors VR,
Resistors Ro to Rn, l variable resistor (1) R variable resistor - The connection point between the variable resistor VB, 1 and the resistor R8 in the R2 group is connected to the second contact side m of the switching relay contact 23. Similarly, the variable resistor VR1' and the resistor R6' to
Rn', one point in the group of variable resistors vR2', for example the connection point between variable resistor VR1' and resistor R6', is connected to the first contact side of the switching relay contact 23. and,
The movable contact C of this relay contact 23 is connected to the A/D converter 2
The output data of this A/D converter 24 is input to the central processing unit (CPU) of the microcomputer via the input interface 25. Also, in order to cause the K CPU to take in the output data of the A/D converter 24 when the intersection of the key matrix board 2o is pressed, for example, a cover having a built-in microswitch is used. - Suppression operation on the surface of the board shall be performed,
The microswitch is configured to be turned on at the time of this operation, and the data acquisition timing of the CPU is controlled by this on signal. After the above data is taken in, the CPU generates a control output to switch the relay contacts 21, 22, and 23 from the break side to the make side m, and then outputs the subsequent output data of the h/6 converter 24 again. After the input, the control output is interrupted and the relay contacts 21, 22, 23 are returned to the original break side. 26 is an output interface, 27 is a relay drive circuit, and the relay contact 21°22.2
This is for switching between 3 and 3. Then, as described above, the CPU performs two data imports at high speed during one key operation, and based on these two import data, the CPU performs a process for detecting the selected point by the key operation. Arithmetic processing is performed, and the result of the arithmetic operation is processed as keyboard selection point input data, and, for example, kanji data corresponding to each selection point is read from a ROM (read only memory).

In the keyboard input circuit configured as described above, when the key matrix selects a certain selection point Xii of the - code 20, first the series resistance group (VR, . . .
The divided voltage in the series resistance group (VR4'~vR2)
') and the break contact side of the relay contact 23, the signal is led to the A/D converter 24, where it is A/D converted,
This converted data passes through the input interface 25 to the CPU.
be taken in. Next, relay contacts 21, 22゜23
are switched at the same time, and the divided voltage in the series resistance group (VR,'~vR2') corresponding to the selection point X becomes a part of the series resistance group (VR1~VR2) and the relay contact 23.
A/
This converted data is input to the input interface 25.
CPUKID is entered through . Then, the CPU selects a selection point = 9 based on the combination of the imported two conversion data.
- Xi+ 'c # Issue.

Note that if the number of vertical conductors and horizontal conductors of the key matrix node 20 is, for example, 256 each, and therefore the number of selection points is 256 x 256 = 65536, then A
The /D converter 24 has an 8-bit output and can convert the input voltage level into 256 types of digital values. Nowadays, monolithic, inexpensive A/D converters can be easily obtained, and it is advantageous that an 8-bit A/D converter with extremely stable performance can be used.

According to the keyboard input circuit as described above, a digital signal corresponding to a selected point is obtained using approximately the same number of resistors as the number of conductors of the key matrix node, three relay contacts, and one A/D converter. The structure is simpler than that of a digital circuit such as an encoder that is required in the past, and the effect of simplifying the structure is particularly great as the number of selected points of the key matrix node increases.

It should be noted that the present invention is not limited to the above embodiment, and other switching circuits may be used in place of the relay contacts 21, 22, and 23.

〔Effect of the invention〕

As described above, according to the keyboard input circuit of the present invention,
Even when there are a large number of selection points in the key matrix, the selection points selected by key operation can be detected using a simple circuit, and this is extremely effective when applying the kanji input key of a Japanese word processor to one card, etc. be.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the selection point of one key matrix, FIG. 2 is a configuration explanatory diagram showing one embodiment of the key matrix input circuit according to the present invention, and FIG. 3 is a diagram showing the selection point of one key matrix. It is a sectional view partially showing an example of the key date of a figure. LR1~LRn, Lo1~Lcn...Conductor, Ro-R
n-4゜Ro'~Rn-1...Resistor, 20...Key matrix port, 21, 22.23...Relay contact, 24...A/D converter. Figure 1

Claims (1)

[Claims] Multiple conductors in the vertical direction and multiple conductors in the horizontal direction
A key matrix node which is arranged in an IJ box shape and is usually insulated from each other, the intersection of the matrices corresponds to the key selection point, and the conductors of the intersection where the key is operated are in contact with each other, and this key matrix date. a first resistor group each having a resistor group connected between each of the vertical conductors of the first resistor group and applying a different voltage to each of the vertical conductors when a constant voltage is applied between both ends; a second resistor group having a resistor group connected between each horizontal conductor of the key matrix date, and applying a different voltage to each horizontal conductor when a constant voltage is applied between both ends; , switching the application of the constant voltage to the first resistor group or the second resistor group during one key operation on the key matrix board, and switching the application of the constant voltage to the first resistor group or the second resistor group; A switching circuit that derives the voltage at one point of the resistor group that does not exist, an A/D converter that digitally converts the voltage derived twice per one key operation by this switching circuit, and this A/D converter. A keyboard input circuit comprising processing means for detecting a key selection point based on output data, and control means for controlling switching of the switching circuit.