JPH09198180A - Key input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a compact structure and also to simplify the key reading operations for a key input device by discriminating the keys in a single frame period of a display signal by means of the key signals of different phases. SOLUTION: A key (a) is read in a section A of timing of a key signal, and a key A is read in a section B of timing of the key signal. In other words, it is discriminated that the key (a) is read in the section A of the key signal against a key signal S1 and an input line I1 and the key A is read in the section B of the key signal respectively. Therefore, it is possible to discriminate keys by a single key signal and in a single step by using the key signals of different phases in a single frame period of a liquid crystal drive signal. As a result, a light turn-off control operation can be omitted for a liquid crystal display device. Thus a compact structure is attained and the key reading operations are simplified. Furthermore, two keys can be discriminated to a single key signal and a single input line and the number of keys can be easily increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key input device such as a small electronic computer or a word processor, and a signal line for transmitting a drive signal for driving a display device and a signal for transmitting a key signal for discriminating the type of the key. The present invention relates to a key input device in which a part of a line is shared.

[0002]

2. Description of the Related Art Conventionally, a small electronic computer is roughly divided into a liquid crystal display device, a key input device, and a computing device. In such an integrated circuit used in a small-sized computer, the configuration is enlarged and the number of pins is increased along with the increase in functions. Although integrated circuits have been downsized due to advances in semiconductor technology, there is a limit to downsizing due to an increase in the number of pins. Therefore, the signal line for transmitting the drive signal of the liquid crystal display device and the signal line for transmitting the key signal of the key input device are made common to reduce the number of pins.

In such a small electronic computer, as described above, the signal line for transmitting the drive signal of the liquid crystal display device and the signal line for transmitting the key signal of the key input device are made common, so that the drive signal is And the key signal must be distinguished. Therefore, as shown in FIG. 7, each liquid crystal drive signal ((a), (b), (c),
(D), ½ bias, ¼ duty), the key reading pulse signal (hatched portion in FIG. 7) is output at regular intervals. This key reading pulse signal determines whether to read the key signal output at the same timing.

On the other hand, the key signal read by this key reading pulse signal is as shown in FIG. 8 ((a), (b),
As shown in (c) and (d), each key signal of a single key is output every time a key is pressed corresponding to each key, and the pressed key is discriminated by this key signal. .

That is, the pressed key is discriminated by a two-step operation in which the reading of the key signal is judged by the key reading pulse signal on the liquid crystal drive signal, and then the pressed key is judged by the key signal. It was done.

As described above, when the key pressed through the two-step operation is discriminated, the output of the liquid crystal drive signal is stopped between the two operations in order to surely read the key signal, and the liquid crystal display is displayed. I had to take action to erase it.

[0007]

As described above,
In a conventional small-sized electronic computer including a key input device and a display device and having a common signal line for transmitting a key signal and a drive signal for the display device, it is necessary to discriminate between the key signals.
Since the stepwise operation is required, the operation for controlling the turn-off of the display device is required between the two operations. For this reason, a configuration for performing the extinguishment control is required, which causes an increase in size and complexity of the configuration.

Therefore, the present invention has been made in view of the above, and an object thereof is to enable a key signal to be read in a one-step operation and to eliminate the need for a light-off control operation in a display device. It is an object of the present invention to provide a key input device which is capable of downsizing the configuration, simplifying the key reading operation, and easily adding a key.

[0009]

In order to achieve the above object, the invention according to claim 1 is a key matrix having a plurality of keys for inputting information consisting of characters and symbols as a key signal, and inputting information. The same input line as an input circuit to which a key signal given through the key in the state of being input is input via an input line, and an input control circuit for controlling the timing at which the input circuit inputs the key signal. A signal for generating a plurality of key signals having different phases within one frame period of a display drive signal for driving the display device and supplying the display drive signal to the display device, corresponding to the plurality of keys respectively connected to the display device. And a key signal generation circuit for outputting the key signal generated through the common key signal output line to the corresponding key.

According to a second aspect of the present invention, in the key input device according to the first aspect, the key signal generating circuit sets the signal level of the key signal to a high level or every n (n> 1) frames of the display drive signal. The input control circuit is changed to a low level alternately, and the input control circuit controls the input circuit to a low level or a high level input enable state according to a signal level of a key signal which alternately changes to a high level or a low level. .

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a key input device according to an embodiment of the invention described in claim 1 or 2.
FIG. 3 is a diagram showing a configuration of the input port shown in FIG. 1, and FIG. 3 is a diagram showing a configuration of a small-sized computer provided with the key input device shown in FIG.

First, before describing the configuration of the key input device, the configuration of a small computer will be described with reference to FIG.

In FIG. 3, the small electronic computer includes a key matrix 1 having a plurality of keys for inputting information consisting of characters and symbols as a key signal, a liquid crystal display device 2, and a key input device, and is a control center of the computer. The large-scale integrated circuit 3 is provided. The key signal is generated from a key input device in the large scale integrated circuit 3, and a key signal output line 5 is shared with a signal line 4 for transmitting a liquid crystal drive signal from the large scale integrated circuit 3 to the liquid crystal display device 2. Each of the keys is given to the corresponding key (shown by a circle in FIG. 3) of the key matrix 1 via a key and the key is pressed. The key that was created is determined.

Next, the configuration of the key input device will be described with reference to FIG.

In FIG. 1, the key input device has key signals S1 to S superimposed on the liquid crystal drive signal of the liquid crystal display device 2.
Key signal generating circuit 7 for generating 4 and input lines I1 to I4
An input port 8 is provided for inputting a key signal via the.

The key signal S1 generated from the key signal generating circuit 7 is supplied from the key signal generating circuit 7 to the keys a, b, c, d.
Is output to the keys a, b, c, and d via the diode D1 connected in the opposite direction toward. Furthermore, the key signal S
1 is output from the key signal generation circuit 7 to the keys A, B, C and D through the diode D3 connected in the forward direction toward the keys a, b, c and d. The key signal S2 generated from the key signal generation circuit 7 is a diode D2 connected in the opposite direction from the key signal generation circuit 7 toward the keys e and f.
Is output to the keys e and f via. Furthermore, the key signal S
2 is output from the key signal generation circuit 7 to the keys E and F via the diode D4 connected in the forward direction toward the keys E and F.

Input line I1 is connected to keys a, e, A, E, input line I2 is connected to keys b, f, B, F, input line I3 is connected to keys c, C, and input line I4. Is the key d,
D.

The key signal generating circuit 7 is, for example, as shown in FIG. 4, each liquid crystal drive signal (1/2 bias, 1 bias).
The key signal (hatched portion in FIG. 4) is output on (/ 4 duty). In FIG. 4, the key signals S1 to S4 are output so that their phases are shifted and their timings are different within one frame period of the liquid crystal drive signal. Further, when the liquid crystal drive signal is divided into, for example, an A section and a B section for every two frame periods (hereinafter referred to as one cycle), a pull-down (low level) key signal is output in the A section and a pull-up (high level) is output in the B section. ) Key signal is output.

Next, the configuration of the input port 8 shown in FIG. 1 will be described with reference to FIG.

In FIG. 2, the input ports 8 are connected in common with their gate terminals connected in series between the power supply VDD and the ground, and the series connection points are connected through the input terminals 9 to the corresponding input lines. And a P-channel FET 10 and N connected to the large-scale integrated circuit 3 shown in FIG.
The channel FET 11 and a timing circuit 12 connected to the commonly connected gate terminals of the FETs 10 and 11 to control switching of the FETs 10 and 11 are configured.

The timing circuit 12 makes the FET 10 conductive in the section A of the timing of the key signal shown in FIG.
The FET 11 is controlled to be in the non-conducting state to be in the pull-up state, and the pull-down key signal is input by forming a current path with the pull-down key signal. In the section B of the timing of the key signal shown in FIG. The input port 8 is controlled to input the pull-up key signal by forming the current path with the pull-up key signal by controlling the FET 10 in the non-conduction state and the FET 11 in the conduction state to set the pull-down state. ing.

Next, the operation of reading the key signal in the above configuration will be described.

First, when the key signal a in FIG. 1 is pressed and the timing of the key signal shown in FIG. 4 is in the section A, the key a is input to the input port 8 when the key signal S1 is output. Is read. That is, it is determined by the large scale integrated circuit 3 that a current flows from the input port 8 through the input line I1, the key a and the diode D1 to the output terminal of the key signal S1 of the key signal generation circuit 7 and the key a is pressed. To be done.

On the other hand, when the key signal a in FIG. 1 is pressed and the timing of the key signal shown in FIG. 4 is in section B, the key signal is in the pull-up state and the input port connected to the input line I1. Since 8 is in the pull-down state, no current path is formed between the input port 8 and the key signal generating circuit 7, and the key a is not read into the input port 8. The keys b, c, d, e, and f are the same as the key a for the corresponding key signals and input lines.

Next, when the key signal A in FIG. 1 is pressed and the timing of the key signal shown in FIG. 4 is in section B, the key A is input port 8 when the key signal S1 is output. Read in. That is, the large-scale integrated circuit 3 determines that the current has flowed from the key signal generation circuit 7 to the input port 8 via the diode D3, the key A, and the input line I1 and the key a has been pressed.

On the other hand, when the key signal A in FIG. 1 is pressed and the timing of the key signal shown in FIG. 4 is in the section A, the key signal is in the pull-down state and the input port 8 connected to the input line I1. Is in a pull-up state, no current path is formed between the input port 8 and the key signal generation circuit 7, and the key A is not read into the input port 8. The keys B, C, D, E, and F are the same as the key A for the corresponding key signals and input lines.

As described above, the key a is read in the section A of the timing of the key signal, while the key A is read in the section B of the timing of the key signal. In other words, for the key signal S1 and the input line I1, the key signal A
The key read in the section is the key a and the key signal B
It is determined that the key read in the section is the key A.

Therefore, by using the key signal whose phase is shifted within the period of one frame of the liquid crystal drive signal,
It is possible to discriminate the key in one step with one key signal. As a result, the operation of turning off the light in the liquid crystal display device becomes unnecessary, and the size of the structure and the key reading operation can be simplified.

Further, it is possible to discriminate the two keys from one key signal and the input line, and it is possible to easily add the keys.

FIG. 5 is a diagram showing a configuration of a key input device according to another embodiment of the invention described in claim 1.

The feature of this embodiment is shown in FIG.
1 to the embodiment shown in FIG.
D4 is deleted, and the key signal generating circuit 13 outputs different key signals S1 to S8 corresponding to the respective keys arranged in different columns, that is, the keys a,
b, c, d and the keys A, B, C, D are made to correspond to different key signals S1, S5, respectively, and the keys e, f are made to correspond to the keys E, F.
The different key signals S2 and S6 are associated with each other, the key signals S1 to S4 are always in the pull-down state as shown in the timing chart of FIG. 6, and the key signals S5 to S8 are always pulled as shown in the timing chart of FIG. The key is read in the up state, and the rest is the same as the above-described embodiment.

Even in such an embodiment, the key can be read in the same manner as the above-mentioned embodiment, and the same effect can be achieved.

The key input device of the present invention is not limited to the input device of a small-sized computer, but can be applied to various portable or stationary information processing devices, word processors, and OA equipment input devices.

[0035]

As described above, according to the present invention, the key discrimination is performed by using the key signals having different phases within one frame period of the display drive signal, so that one-step operation is performed. It is possible to discriminate the key entered in step (2), and it is possible to eliminate the need for the operation of the extinguishing control in the display device. This makes it possible to reduce the size of the configuration and simplify the key reading operation.

Further, since the level of the key signal is alternately changed for each predetermined section and the input state of the input circuit for receiving the key signal is changed, it is possible to easily add the key.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a key input device according to an embodiment of the invention described in claim 1 or 2.

FIG. 2 is a diagram showing a configuration of an input port shown in FIG.

FIG. 3 is a diagram showing a configuration of a small-sized computer including the key input device of the present invention.

FIG. 4 is a diagram showing a timing chart of the apparatus shown in FIG.

FIG. 5 is a diagram showing a configuration of a key input device according to another embodiment of the invention described in claim 1 or 2.

6 is a diagram showing a timing chart of the device shown in FIG.

FIG. 7 is a diagram showing a timing chart of a conventional key input device.

FIG. 8 is a diagram showing key signals in a conventional key input device.

[Explanation of symbols]

 1 key matrix 2 liquid crystal display device 3 large-scale integrated circuit 4 signal line 5 key signal output line 6 input line 7, 13 key signal generation circuit 8 input port 9 input terminal 10 P-channel FET 11 N-channel FET 12 timing circuit D1 ~ D4 diode

Claims (2)

[Claims] 1. A key matrix having a plurality of keys for inputting information consisting of characters and symbols as a key signal, and a key signal given through the key in a state of inputting information through an input line. An input circuit to be input, an input control circuit for controlling the timing when the input circuit inputs a key signal, and a display for driving a display device corresponding to each of the plurality of keys connected to the same input line. A plurality of key signals having different phases are generated within one frame period of the drive signal, and the generated key signals are associated with the signal line for supplying the display drive signal to the display device through the common key signal output line. And a key signal generation circuit for outputting to the key. 2. The key signal generation circuit alternately changes the signal level of the key signal to a high level or a low level for every n (n> 1) frames of the display drive signal, and the input control circuit has a high level. 2. The key input device according to claim 1, wherein the input circuit is controlled to a low level or high level input enable state according to a signal level of a key signal that alternately changes to a level or a low level.