JPS6327726B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] A switch circuit is attached to a keyboard with a matrix circuit configuration, and when the power is turned on, a specific key switch is set to the input state, and then a specific key switch is set to the input state by the first pulse of a clock pulse for sending a specific address signal. Then,
It is returned to the open state, and thereafter the open state is maintained by refreshing the clock pulse for sending a specific address signal.

This makes it possible to initialize the keyboard easily and inexpensively.

[Industrial application field]

The present invention relates to a keyboard initial setting (first keystroke) method.

Keyboards are commonly used as input terminal devices for information processing systems, and when you get one, you input information by pressing a key switch on the keyboard to select input information. It is necessary to constantly press the specified key switch for the first time, and there is a desire for a simple method for automatically performing the required key switch for the first press.

[Conventional technology]

The keyboard of the key input terminal that interfaces with the central processing unit of an information processing system generates a digital code signal corresponding to the keystroke input from the key switches arranged on the matrix circuit and sends it to the central processing unit. In this case, the general method is to send an address scanning signal for detecting a keystroke input from an encoder to the X side and Y side of the matrix circuit.

The circuit diagram in attached Figure 1 illustrates this, and 1
2 is an encoder connected to the central processing unit via signal lines 4 and 5, and 3 is provided between the matrix circuit 1 and encoder 2, and is connected to the Y-side input. It is a multiplexer that also performs address detection. Note that the X-side input multiplexer function is housed in the encoder 2 described above. Further, a signal line 4 is a switch code signal line for detecting key press input sent to the central processing unit, and a signal line 5 is a clock signal line for specifying an address.

In a keyboard equipped with such a matrix circuit, for example, a matrix circuit consisting of 8 (m = 8) on the X side and 16 (n = 16) on the Y side has a 7-bit configuration (of the 7 bits, 4 bits are Y
By sequentially sending out the address scanning signals of the side selection bits (3 bits apply to the X side selection bits), a key switch of a keystroke input is detected.

Incidentally, the circuit diagram in FIG. 1 attached hereto shows a 3-bit configuration, in which of the clock signal lines 5, A is the clock signal line for the least significant bit, B is the clock signal line for the middle bit, and C is the clock signal line for the most significant bit. Using the upper bit clock signal line, for example, fix the lower bit signal line A and scan from Xo to Xm on the X side, then move to the middle bit signal line B and scan from Xo to Xm on the X side. The scanning is repeated until the signal line C of the upper bit is scanned, and finally the signal line C of the upper bit is scanned, and the same is repeated on the Y side.

[Problem that the invention seeks to solve]

By the way, conventionally, in the initial stage of keyboard input, it is often the case that a key switch for selecting specific input information is pressed for the first time. For example, when inputting only English characters into an information processing system for the first time, or when inputting only English characters, it is necessary to constantly press a specific key switch on the keyboard for the first time.

In such a case, an input method similar to the conventional automatic key input has been considered, such as providing a memory circuit in which the processing procedure is programmed in the encoder 2.

However, providing a programmed memory circuit in the encoder 2 increases the cost considerably and is not economically desirable.

The present invention proposes a method for carrying out such an initial set (initial input) simply and inexpensively.

[Means for solving problems]

The purpose of this is to attach a switch circuit to a keyboard with a matrix circuit configuration to which a key switch is connected, to set the key switch for selecting specific input information to the input state when the power is turned on, and then to set the key switch for selecting specific input information to the input state. This is achieved by an initial setting method in which a pulse signal is input to return the key switch for selecting the specific input information to the open state, and thereafter the open state is maintained by refreshing the clock pulse for sending the specific address signal. .

[Effect]

The present invention includes a switch circuit to set a specific key switch to an input state when the power is turned on.
Next, it is returned to the open state by the first pulse of the clock pulse for sending a specific address signal, and
Thereafter, the open state is maintained by refreshing the clock pulse for sending a specific address signal.
Such a switch circuit is simple and inexpensive.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached circuit diagram of FIG. 1 and FIG. 2 showing an operation time chart of the circuit of FIG. 1.

In FIG. 1, the basic structure and functions of the encoder 2, multiplexer 3, etc. for detecting key input of the matrix circuit 1 are the same as described above. In addition, as described above, scanning on the clock signal line 5 is a scanning method in which scanning is performed sequentially from the clock signal line A for lower bits to the clock signal line C for upper bits, and this scanning is repeated. Keystroke input is detected by .

In the present invention, a switch circuit consisting of an FF circuit 7, a NAND gate element 8, and an inverter 9 is added to such a conventional configuration. The FF circuit 7 is a flip-flop with a negative output connected to the clock signal line C of the upper bit by a signal line CL and operated by the clock pulse signal. Moreover, at first, when the power supply Vcc is turned on, the encoder 2
When a reset signal is input from the FF circuit 7 through the signal line RS, the output of the FF circuit 7 is at H level.

In addition, the inverter 9 is connected to a specific key switch K.
(The so-called key switch for selecting specific input information that is input for the first time when the power is turned on) X side address signal line
_Furthermore , the outputs of this inverter 9 and the FF circuit 7 are connected to a NAND gate element 8, and the output of the NAND gate element 8 is connected to the Y side address signal line _Y1 of a specific key switch K. is connected to by the signal line OUT.

Next, the operation of this keyboard circuit will be explained with reference to FIG.

In the figure, waveforms Xo to Xm are clock pulses that sequentially scan the X side signal lines Xo to Xm of the matrix circuit 1, and waveforms A to C are clock pulses that sequentially scan the X side signal lines Xo to Xm of the matrix circuit 1.
Based on the counting pulse from C, the multiplexer 3 sequentially selects the Y side signal lines Yo to Yn. As shown in the figure, the period between the falling edge of the pulse waveform A and the falling edge of the pulse waveform C is the key scan period, and all the key switches in the matrix circuit 1 are scanned once to detect the key switch of the key input.

In addition, waveform Q is the output waveform of FF circuit 7, waveform OUT
is the output waveform of the NAND gate element 8.

Thus, when the keyboard power supply Vcc is turned on, the output of the FF circuit 7 becomes H level as described above, and at that point the upper bit clock signal line C
If is not selected, it is at H level. At the same time as the power is turned on, the lower bit clock signal line A is selected, and when a clock pulse (Low pulse) is input to the address signal line _X1 , the inverter 9 operates and the output becomes H level. Then, depending on the H level of both outputs, the NAND gate element 8
outputs an L level, and the signal line _Y1 becomes an L signal through the output line OUT. On the other hand, as mentioned above, since the L signal is input from the signal _line
become.

Next, when the clock signal line C of the upper bit is selected by sequential scanning, a clock pulse is input to the FF circuit through the signal line CL, and as a result,
The output of the FF circuit 7 becomes L level. On the other hand, since the inverter 9 is connected to the X-side address signal line _X1 , which is refreshed faster than the bit clock signal line, its output is constantly at the H level.
Due to the L level from the FF circuit 7, the NAND gate element 8 outputs an H level, and _Y1 becomes an H signal.
The specific key switch K returns to the non-keyed state (open state).

In this way, while the output of the inverter 9 is constantly at the H level, the output of the FF circuit 7 is also refreshed repeatedly by the clock signal line C of the upper bit and is at the L level, and as a result,
The NAND gate element 8 constantly outputs an H signal, the signal line OUT is at the H level, and a specific key switch K maintains a non-keyed state (open state). Therefore, the additional circuit according to the present invention has no circuit meaning except when the power is turned on, and becomes a circuit that is activated only when the power is turned on.

Note that in the above embodiment, the clock pulse for sending a specific address signal is the clock signal of the upper bit, but this is because the scanning of the clock signal of the upper bit is normally performed near the end of one scan, so _Y1 is set to H. This is because the signal can be retained for a long time.
However, once _Y1 can be held at the H signal, there is no need to worry about the scanning signal near the end.

Furthermore, when this switch circuit is no longer needed, the output line OUT can be disconnected, and it is also easy to connect this switch circuit to another part.

〔Effect of the invention〕

As can be seen from the above description, according to the present invention, there is an advantage that a specific key switch that can automatically input keystrokes only once when the power is turned on can be easily and inexpensively inserted.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram with a switch circuit according to the present invention, and FIG. 2 is an operation timing chart of FIG. 1. In the figure, 1 is a matrix circuit, 2 is an encoder, 3 is a multiplexer, 4 is a switch code signal line for detecting keystroke input, 5 is a clock signal line for address specification, 6 is a key switch, 7 is an FF circuit,
8 is a NAND gate element, 9 is an inverter, Vcc
indicates the power supply.

Claims (1)

[Claims] 1. A switch circuit is attached to a keyboard with a matrix circuit configuration to which a key switch is connected, and when the power is turned on, the key switch for selecting specific input information is set to the input state, and then the first pulse signal of the clock pulse for sending a specific address signal is set to the input state. A method for initializing a keyboard, characterized in that the key switch for selecting the specific input information is returned to an open state upon input, and thereafter the open state is maintained by refreshing a clock pulse for sending out the specific address signal. .