JPS62219017A - Keyboard circuit - Google Patents

Abstract

PURPOSE:To reduce the number of parts of a switching circuit and the power consumption and to scan contacts at high speed by adding a turn-on contact detecting circuit and a parallel/serial transforming circuit to a key matrix to reduce the number of interface signals. CONSTITUTION:This keyboard circuit consists of a key matrix 2 where plural key switches 1 are arranged in a matrix, a turn-on contact detecting circuit 12 which has two kinds of threshold level and consists of plural comparator amplifying circuits, and a parallel/serial contransforming circuit 13 which transforms the parallel output of the turn-on contact detecting circuit 12 to one serial data and generates a control signal which indicates it to the reception side that the duration of the turn-on state of a depressed contact can be discriminated and serial data can be received. Since the turn-on contact detecting circuit 12 and the parallel/serial transforming circuit 13 are added to the key matrix 2, the serial data signal and the control signal are enough for interface to each control circuit system even when one key matrix 2 is connected to two control circuits independent of each other of a telephone type terminal equipment or the like by switching and is controlled, and thus, the number of interface signals is reduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention arranges a plurality of key switches in a matrix, monitors the on/off states of the plurality of key switches in the key matrix, and detects the on-state keys. The present invention relates to a keyboard circuit that generates a key operation signal indicating a switch and sends the key operation signal to a transmission line for input into a computer or the like, and particularly relates to improvements for reducing the number of interface signals and power consumption.

[Conventional technology]

As shown in FIG. 9, a conventional keyboard includes a key matrix 2 in which a plurality of key switches 1 (the basic structure of which is enlarged and shown in a chain line) is arranged in a matrix, and The key scanning control circuit 3 monitors the on/off state of the key switch 1 and generates a key operation signal indicating the key switch 1 is in the on state. Terminal S, ~S, 1 is key matrix 1
The terminals R, -R, are connected to the lines of each column, and are connected to power supplies V, C via resistors 4, respectively.

The key scanning control circuit 3 sequentially outputs scanning signals from the terminals 31 to S7, and the scanning signal is input to one of the terminals R0 to RI through the key switch 1 which is in an on state. Depending on the combination of the terminal to which the scanning signal is output and the terminal to which the scanning signal is input, the key switch 1 is turned on.
, and detect which key switch 1 has been pressed.

The key scanning control circuit 3 generates key operation data corresponding to the key switch 1 whose ON state has been detected, and transmits it to the upper control unit via the system bus 5.

[Problem that the invention seeks to solve]

In the case of conventional keyboard circuits, one key matrix is connected to two independent control circuits and controlled by switching, for example in a telephone terminal device, when the device power is turned on, key matrix 2 is connected to the device control section. and scan,
When the device is powered off, the key matrix 2 needs to be connected to the telephone circuit and scanned.

FIG. 10 shows an example of a circuit of such a telephone type terminal device, in which a control circuit 6. A first group of relays 8 and a second group of relays 9 are provided between the key matrix 2 and the telephone circuit 6.
Scanning signal from 1 to 1st relay group 8 (811 to S0)
A third relay group 1 is connected between the return signal (R1a to R□) line and the second relay group 9 to the telephone circuit 63.
0 is inserted, and the first to third groups of relays 8 to 10 are controlled by the contact switching control circuit 11. For example, the first and second groups of relays 8.9 are controlled by the control circuit 6b. When switched to the control circuit 6. The scanning signal (S+b''S,, b) from the key matrix 2 is given as a scanning signal (S, ~S,) via the first group of relays 8, and each return signal (S, ~S,) from the key matrix 2 is The R+ "" R-) line is connected to each return signal (Rr b to R1,
lb) connected to the line.

In this type of use (example), the two independent control circuit systems must be electrically isolated, so generally the 10th
As shown in the figure, at the demarcation point between each control circuit system and the key matrix 2, a method is used in which switching is performed using a relay or the like. ~R, , ) both have a large number of signals, so in the conventional case, ■The number of relays and their drive circuit components is large, ■The connection distance is relatively short, ■The number of connecting cables is large, ■The relay etc. and its drive circuit have a large number of parts, which has the disadvantage of high power consumption.

SUMMARY OF THE INVENTION An object of the present invention is to provide a keyboard circuit that overcomes these drawbacks.

[Means for solving problems]

The keyboard circuit of the present invention includes an on-contact detection circuit composed of a plurality of comparator circuits for detecting the on/off states of key switches on a key matrix in which a plurality of key switches are arranged in a matrix, and A parallel-to-serial conversion function that converts parallel data from the detection circuit into serial data, generates and receives one control signal that transmits sampling timing and key switch on time information to the receiving side, and receives power from the receiving side. It is characterized by having a circuit.

〔Example〕

Next, one embodiment of the present invention will be described using the drawings.

FIG. 1 is a block diagram of a keyboard circuit according to an embodiment of the present invention. This keyboard circuit includes a key matrix 2 in which a plurality of key switches 1 are arranged in a matrix, an on-contact detection circuit 12 having two different threshold levels, each composed of a plurality of comparator amplifier circuits, Converts the parallel output of the on-contact detection circuit 12 into one serial data, and generates a control signal indicating to the receiving side that it is possible to identify the duration of the on state of the push contact and to receive the serial data. , and a parallel/serial conversion circuit 13 having a function of receiving power from the receiving side.

As mentioned above, the on-contact detection circuit 1 is connected to the key matrix 2.
By adding 2 and the parallel-to-serial conversion circuit 13, even if one key matrix and 2 are connected to two independent control circuits and controlled by switching, as in the above-mentioned telephone terminal device, each The interface with the control circuit system can be performed using the above-mentioned serial data signal and control signal, so the number of signals does not increase as shown in FIG. 10 mentioned above.
Interface signals have been reduced.

Here, FIG. 2 shows an example of the circuit configuration of the on-contact detection circuit 12, the key matrix 2, and the on-contact detection circuit 12.
In order to detect the on/off state of the key matrix 2, a plurality of comparator amplifier circuits 14y1 to 14ya, which are arranged in the X direction and the Y direction and have two types of threshold levels, are shown. 14. , to 14-, the circuit configuration of the on-contact detection circuit 12 is shown.

Comparator amplifier circuit 14. A Y-direction on-contact detection signal is sent from the 14y7 side, and the comparator amplifier circuit 14. , to 14X, an X-direction on-contact detection signal is sent out from the sides. Furthermore, formation of the on-detection signal in the on-contact detection circuit 12 can be performed as follows.

That is, as shown in FIG.
-Pull-up resistor 15yI for each signal line of y1
~15y7 is connected, and also XI~X.

Pull-down resistors 15. ,~15
I is connected, and a transistor 16Q is provided to detect the current flowing through the pull-up resistor, the turned-on key switch, and the pull-down resistor when any key switch 1 is turned on, and when any key switch 1 is turned on, the pull amplifier resistor is connected. , the key switch, the pull-down resistor, and the base resistor 16R, this causes the transistor 16° to operate, and its collector output is taken out as an on-detection signal. Furthermore, when key switch 1 is turned on, the X and y signal lines of that key switch are at the same level, and the threshold level of each (two types) of comparator amplifier circuits in each direction is set to 2.
This is converted into a value signal, and on-contact detection signals in the Y direction and the X direction are sent out.

Further, the above-mentioned parallel-to-serial conversion circuit 13 can be constituted by a transmission shift register 18, a transmission shift register control circuit 19, and a driver circuit 20, as shown in FIG. In other words, this parallel-to-serial conversion circuit is
A transmission shift register 18 that converts parallel data from the on-contact detection circuit 12 into serial data, and a shift clock d and a data set signal C1 output as shown in the time chart of FIG. 4 to supply this transmission shift register 18. A transmission shift register control circuit 19 that generates a control signal g serving as a signal enable signal f and a serial data acquisition signal to the receiving side (a signal instructing the sampling time to the receiving side);
In addition to outputting current to the data line based on the serial data e as shown in the figure, the driver circuit 20 also serves to receive power from the data line.

The on-contact detection signal shown in FIG. 4 from the on-contact detection circuit 12 is given to the transmission shift register control circuit 19, and the on-contact detection signal at that time is sent to the transmission shift register as parallel data signals 1 to N. 18, where it is converted into serial data e using a shift clock d synchronized with the lock signal a as shown in FIG. A control signal g as shown in FIG. 4 is sent from the register control circuit 19 side to the receiving side. In this way, it is only necessary to send serial data e and one control signal g to the receiving side,
Therefore, even if a switching circuit is installed in the middle of an application in which two control circuits are switched and connected, the number of parts in the switching circuit can be reduced, and on the receiving side, serial data can be converted to parallel data. All you have to do is convert.

Examples of how the keyboard circuit of this embodiment is used are shown in FIGS. 5 to 8 below.

First, FIG. 5 shows a block diagram of the circuit including the receiving side. The receiving side circuit reproduces the parallel data based on the serial data and its control signal from the transmitting side shown in Figure 1, and generates an output enable signal that is an identification signal for the duration of the ON state of the push contact. At the same time, the key contact data 1 to N from the serial-to-parallel converter circuit 21 is sent to the serial-to-parallel converter circuit 21, which has the function of supplying power to the transmitting side, and the upper control unit via the system bus 22. It is comprised of a control circuit 23 that performs interface control for transmission.

As shown in FIG. 6, the serial-to-parallel conversion circuit 21 on the receiving side includes a reception shift register 24 that converts serial data e (FIG. 7) into parallel data, and a control signal g (FIG. 7).
Based on the shift clock h of the reception shift register 24
, a reception shift register control circuit 25 that generates an output enable signal i (FIG. 7), and a receiver circuit 26 that not only reproduces serial data based on current changes in the data line but also supplies power to the data line. Can be configured. Note that FIG. 7 shows a time chart of the signals in FIG. 6.

Figure 8 is applied to the usage example shown in Figure 10.
This is a replacement when the keyboard circuit of this embodiment is used.

As shown in FIG. 8, a serial-to-parallel conversion circuit A27 is provided on the telephone circuit 61 side, and a serial-to-parallel conversion circuit 82B and a parallel-to-serial conversion circuit B29 are provided on the control circuit 6b side. In the illustrated state, The keyboard circuit parallel-to-serial conversion circuit 13 and the serial-to-parallel conversion circuit A27 on the six telephone circuit sides are connected to the switching circuit 3.
0 through a first switching contact 31 and a second switching contact 32, thereby allowing the transmission of serial data and control signals as described above. Switching of the switching circuit 30 is performed by the control circuit 6b, and in the case shown, the telephone circuit 6a side is the receiving side, but when the control circuit 6b side is the receiving side, , the first switching contact 3 of the switching circuit 30
1 may be switched to the serial/parallel conversion circuit 828 side.

In addition, in FIG. 8, the serial/parallel converter circuit 828 and the parallel/serial converter circuit B29 are integrated into a 1-chip CPU in the circuit actually used.
etc., and can be included in the control circuit 6b.

〔Effect of the invention〕

As explained above, the present invention adds an on-contact detection circuit and a parallel-to-serial conversion circuit to the key matrix and reduces the number of interface signals. The number of parts can be reduced, ■ connection cables can be easily extended, ■ power consumption is reduced, and ■ contact scanning speed is increased.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram showing an embodiment of the present invention, Fig. 2 is a circuit block diagram of an example of an on-contact detection circuit and a diagram showing the connection relationship with a key matrix, and Fig. 3 is a diagram of a parallel-to-serial conversion circuit. A circuit block diagram showing an example, Fig. 4 is a diagram showing a time chart of a parallel-serial conversion circuit, Fig. 5 is a diagram showing the keyboard circuit of Fig. 1 and a circuit on the receiving side, Fig. 6 is a diagram showing the serial/parallel circuit on the receiving side. Figure 7 is a circuit block diagram showing an example of a conversion circuit; Figure 7 is a diagram showing a time chart of a serial-to-parallel conversion circuit; Figure 8 is a circuit block diagram showing an example of the use of the keyboard circuit in Figure 1; Figure 9 is a conventional Diagram showing the circuit configuration of the keyboard, No. 10
The figure is a circuit diagram showing an example of the use of a conventional circuit. 1...Key switch 2...Key matrix 6,...Telephone circuit 6b...Control circuit 12...On contact detection circuit 13.29...Parallel-serial conversion circuit 14y+~14. ．． 1.14.1 to 14X1... Comparator width circuit 18... Transmission shift register 19... Transmission shift register control circuit 21.27.2
8...Serial-to-parallel conversion circuit 30...Switching circuit agent Yoshiyuki Iwasa
× Figure 3 Figure 4 Figure 6 Figure 7 K Large K-

Claims (1)

[Claims] (1) An on-contact detection circuit consisting of multiple comparator circuits to detect the on/off states of key switches on a key matrix arranged in a matrix, and a It has a parallel-to-serial conversion circuit that converts parallel data into serial data, generates one control signal that transmits sampling timing and key switch on time information to the receiving side, and receives power from the receiving side. A keyboard circuit featuring: