JPS5819621Y2 - key identification circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a key identification circuit that provides a key switch at the intersection of two sets of signal lines and identifies whether or not each key switch has been pressed. The purpose is to reduce unnecessary noise.

Generally, the key identification circuit is located at the intersection of the key human input signal lines 1 to 3 and the key output signal lines 4 to 6, as shown in FIG.
key switches 7 to 15 are provided, and the key output line 4
The second key identification signal input terminals 19 to 21 are connected to the other input terminals of the two-man powered AND gates 16 to 18, one input terminal of which is connected to the two-man powered AND gate 16.
~18 output terminals are connected to each input terminal of the three-man power OR gate 22, and the output terminal of the three-man power OR gate 22 is connected to the key identification signal output terminal 23, while the above-mentioned key human power signal lines 1 to 3 are connected to the key identification signal output terminal 23. First key identification signal input terminals 24 to 26
was connected.

In order to identify which key has been pressed in a key identification circuit having such a configuration, for example, only the key human input signal line 1 is set to logic level "1" and the second key identification signal input terminals 19 to 19 are connected to each other. 21 in order from "O" to "1", then only the key human input signal line 2 is set to "1", and then the key identification signal input terminals 19 to 21 are set in order from "o" to '1', and then Key human power signal line 3 only 1”
As a result, the key identification signal input terminals 19 to 21 are set to 0 in order.
”, then repeat the cycle of going from N to jl.

In the above process, the key identification signal output terminal 23
The key human power signal lines 1 to 3 are from “0” to “1”
The key switches 7-15 are identified by determining which one of the key identification signal input terminals 19-21 becomes "1".

However, in the above-mentioned key identification circuit, the key switches T to 15 placed at the intersections of the key human input signal lines 1 to 3 and the key output signal lines 4 to 6, and the first key identification signal input connected to those signal lines. Terminals 24 to 26 or multiple 2
The circuit portion including the human-powered AND gates 16 to 18 is separated, so that the key human-powered signal lines 1 to 3 and the key output signal lines 4 to 6 are stretched long, and the key human-powered signal lines 1 to 3 are connected to each other. If a pulse-like signal that alternates between "1" and "1" is constantly generated, there is a drawback that there is an increased possibility that noise will travel from the key human input signal lines 1 to 3 to other parts.

For example, if the F'M/
When an AM audio broadcast receiving section is installed, there is a drawback that the F'M/AM audio broadcast receiving section is interfered with by the above-mentioned noise.

Another conventional circuit that overcomes the drawbacks of the conventional circuit is as follows.

In other words, the other conventional circuit does not identify each of the multiple key switches, but first detects that any key switch has been pressed, and then detects that any key switch has been pressed. By identifying which key switch was pressed only for a certain period of time after detecting the
This is intended to avoid the generation of a pulsed signal having a value of 1'' and to avoid the influence of noise due to this pulsed signal.

Hereinafter, this conventional circuit will be explained in detail with reference to the drawings.

FIG. 2 shows an example of the configuration of the key identification circuit of the secondary path;
In the figure, 50 to 52 are first key identification signal input terminals, each of which is connected to one input terminal of the three first two-man OR games 4 (53 to 55).

The output terminal of a first RS flip-flop 56 is integrally connected to the other input terminal of the two-man OR gates 53 to 55, and the reset terminal and set terminal of the RS flip-flop 56 are connected to the output terminal of the first RS flip-flop 56. No. 2 key identification signal input terminals (57, 58) are connected.

Key human power signal lines 59 to 61 are connected to the output terminals of the two human power OR gates 53 to 55.

Key output signal lines 62 to 64 are arranged in a matrix so as to have nine intersections with the key human input signal lines 59 to 61.

Key switches 65 to 73 are installed at each of the above intersections to connect the two sets of signal lines.

The key output signal lines 62 to 64 are connected to respective input terminals of a second three-person OR gate 74, and the output terminal of the three-person OR gate 74 is connected to a first key identification signal output terminal 75.

Further, the key output signal lines 62 to 64 are connected to one input terminal of three two-man power AND gates 76 to T8,
Other input terminals of the two-man power AND gates 76-78 are connected to three third key identification signal input terminals 79-81, respectively.

The output terminals of the two-manpower AND gates 76 to 78 are connected to respective input terminals of a third three-manpower OR gate 81, and the output terminal of the three-manpower OR gate 82 is connected to a second key identification signal output terminal 83. has been done.

Next, the operation of the key identification circuit will be explained.

When the set/reset terminals of the RS flip-flop 56 are both "O", the level of the output terminal of the RS flip-flop 56 does not change, and when the set terminal becomes 1", the output terminal becomes 61", and the reset terminal becomes "0". When it becomes 1", the output terminal becomes O".

As the first stage of key identification, a logic level "1" signal is sent to the second key identification signal input terminal 57 connected to the set terminal of the first RS flip-flop 56, and a second key signal connected to the reset terminal is sent. O'' to identification signal input terminal 58
When a signal is applied, the RS flip-flop 56
The output terminal of will be 1”.

Therefore, the logic level of the output terminals of the three first two-man OR gates 53-55 and the key human-power signal lines 59-61 becomes "1".

In the above state, when the key switches 65-73 are not pressed, the key output signal lines 62-64 are all at the 0'' level.

Therefore, the first key identification signal output terminal 75 remains at the 0'' level.

However, if any of the key switches 65-73 is pressed, any of the key output signal lines 62-64
■", and the first key identification signal output terminal 75 becomes 1".

When the first key identification signal output terminal 75 becomes "1", it is determined that one of the keys has been pressed, although it is not yet known which key was pressed.

1" to the second key identification signal input terminal 58 connected to the reset terminal of the first RS flip-flop 56, and 1" to the second key identification signal input terminal 57 connected to the set terminal. In addition, the output terminal of the RS flip-flop 56 becomes 0''.

This completes the first stage of key identification. Once the first stage is completed, the process moves on to the second stage of key identification.

In the second stage of key identification, for example, only the input terminal 50 of the first key identification signal input terminals 50 to 52 is set to "1",
The other input terminals are turned on.

Then, only one terminal of the third key identification signal input terminals T9 to T81 is set to '1' in order.

Next, the first key identification signal input terminal 51 is set to 1, and the third key identification signal input terminals 79 to 81 are sequentially set to 1 one by one.

Next, the first key identification signal input terminal 52 is set to "1", and the third key identification signal input terminals 79 to 81 are sequentially set to "1" one by one.

This completes the second stage of key identification, and the second key identification signal output terminal 83 is connected to the first key identification signal input terminal 50 to
52 and the third key identification signal input terminals 79 to 81 become "1", it is possible to identify which key has been pressed.

For example, when the key switch 72 is pressed, the second key identification signal output terminal 83 becomes n ln only when the key human input signal line 61 is 1'' and the key output signal line 80 is 1', and the key switch 72 is pressed. It can be identified that 72 was pressed.

After the first and second stages of key identification are completed, another circuit block performs the work corresponding to the identified key.

By performing key identification using the above procedure, it is possible to constantly apply a pulse-like signal between 0 and 1, which occurs in the second stage of key identification, to the key human input signal lines 59 to 61. Preventable and therefore key human power signal line 59
It is possible to reduce the possibility that noise is generated from the pulsed signals generated in the key input signal lines 59 to 61 and that the noise adversely affects other circuits disposed near the key human input signal lines 59 to 61.

Similarly, if the parts other than the key switches 65 to 73 are housed together with other circuits in a single chip semiconductor circuit, the output terminals of the two-man OR gates 53 to 55 also serve as output terminals for the semiconductor circuit, Key switch 65-73
Since the key human power signal lines 59 to 61 and the key output signal lines 62 to 64 are wired long, suppressing the pulse-like signals generated in the key human power signal lines 59 to 61 as much as possible is called noise reduction. It is particularly effective from this point of view.

The present invention, as shown in FIG. 2, uses a key human power signal line 61 to detect whether or not a key switch in a group, for example, one of the key switches 11 to 73, is still being pressed. This is intended to prevent pulse-like signals of "0" and 1 from being applied.

FIG. 3 shows a configuration example of the key identification circuit of the present invention, and the same reference numerals as in FIG. 2 indicate the same configuration elements.

The difference in FIG. 3 from FIG. 2 is that a second RS flip-flop 84 is provided, and a first RS flip-flop 84 is provided at its set terminal.
A key identification signal input terminal 52 is connected to the key identification signal input terminal 52, one input terminal of the first two-man OR gate 55 is connected to its output terminal, and a fourth key identification signal input terminal 85 is connected to its reset terminal. It is that you are.

The function of this RS flip-flop 84 will be explained next.

First, consider the case where any of the key switches 65 to 67 is pressed.

The first stage of key identification is the same as in the description of FIG.

Next, proceeding to the second stage of key identification, the first key identification signal input terminals 50 to 52 are sequentially set to "1", and the second
It is possible to identify which of the key switches 65 to 67 has been pressed in the same manner as in the explanation of the figures.

However, unlike the case in FIG. 2, since the RSS flip-flop 8 is provided, in the second stage the fourth key identification signal input terminal 85 is O" and the output terminal of the RS flip-flop 84 is "0". If the first key identification signal input terminal 52 becomes 1", the RS flip-flop 84
The output terminal becomes "1" and remains "1" from then on.

Therefore, when repeating the first to second steps described in FIG.
It is necessary to reset the output terminal of the RS flip-flop 84 to '0' by setting the key identification signal input terminal 52 to '1' and the first key identification signal input terminal 52 to '0'.

Next, let us consider a case in which the flip-flop 84 is activated, for example, when any of the key switches 71 to 73 is pressed.

As in the case of the explanation of FIG. 2, it is possible to identify which key has been pressed after passing through the first and second stages of key identification.

However, unlike the case described in FIG. 2, the output terminal of the RS flip-flop 84 remains at 1'' during the second stage.

Next, let us move on to a task corresponding to any of the identified key switches 71 to 73, and consider that in that task it is necessary to repeatedly determine whether the identified key is still pressed.

In that case, "1" is input to the first key identification signal input terminal 52.
is applied many times, and at the same time, 1'' is applied many times to any one of the third key identification signal input terminals 79 to 81.

However, n 1 n at the first key identification signal input terminal 52
Even if is applied in a pulse-like manner many times, the output terminal of the RS flip-flop 84 remains at "1", so during that time there is no pulse-like signal that takes "1" and "0" on the key input signal line 61.

Then, before moving on to the first stage of key identification, in which it is detected that any key has been pressed, the reset terminal of the RS flip-flop 84 is set to "1".
Set the set terminal to “0” and set its output terminal to “0” I)
-t=knit.

In the configuration shown in FIG. 3, when any one of the key switches 71 to 73 is identified many times in succession, a pulse-like signal of "0" and "1" is applied to the key human input signal line 61 during that time. can be prevented.

Note that in the above embodiment, the second RS flip-flop 84
is provided only for the OR gate 55, but it may be provided for all OR gates 53-55.

As described above, according to the present invention, unlike the case where key switches provided at each intersection of a plurality of key human input signal lines and a plurality of key output signal lines are individually identified, the key identification signal input terminal of the first group At this time, the output of the OR gate that inputs all the outputs of the key output signal line is generated, and it is detected that one of the key switches becomes conductive. 1st. A predetermined pulse is input to the second key identification signal input terminal to identify a key switch in a conductive state, and a plurality of first key identification signals are input to one input terminal of the plurality of first OR gates. Since a second RS flip-flop is provided on part or all of the connection line to which the input terminal is connected, the key switch can be used to repeatedly identify one of a group of key switches. “O” between human signal lines
It is possible to prevent a pulse signal of 1" from being applied.

Therefore, even when a key switch is pressed intermittently, the noise generated when detecting the key switch being pressed can be extremely reduced, which is a practical advantage.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram of a conventional key identification circuit, FIG. 2 is a wiring diagram of another conventional key identification circuit, and FIG. 3 is a wiring diagram of an embodiment of the key identification circuit of the present invention. 50.51.52...First key identification signal input terminal, 53, 54, 55.74.82...
OR gate, 56...RS flip-flop,
57゜58... Second key identification signal input terminal,
59゜60.61...Key human power signal line, 62
, 63゜64...Key output signal line, 65~T
3... Key switch, 75... First key identification signal output terminal, 76.77.78...A
ND gate, 79,80°81...Third key identification signal input terminal, 83...Second key identification signal output terminal, 84...Second RS Flip-flop, 85...Fourth key identification signal input terminal.

Claims (1)

[Scope of utility model registration request] A plurality of key human power signal lines and a plurality of key output signal lines intersect in a matrix, a plurality of key switches are respectively connected to each intersection, and an output terminal is connected to each of the plurality of key human power signal lines; a plurality of first OR gates each having a plurality of first key identification signal input terminals connected to its input terminal, an output terminal being connected to the other input terminal of the plurality of first OR gates, and a reset terminal; and a first RS flip-flop whose set terminal is connected to a plurality of second key identification signal input terminals, whose input end is pre-connected to the plurality of key output signal lines, and whose output terminal is connected to a first key identification signal input terminal. One input terminal is connected to each of the second OR gate to which the identification signal output terminal is connected and the plurality of key output signal lines, and each of the plurality of third key identification signal input terminals is connected to the other input terminal. the plurality of AND gates and the output terminals of the plurality of AND gates are respectively connected to the input terminals,
a third OR gate whose output terminal is connected to the second key identification signal output terminal, and the third OR gate is controlled by simultaneous output from the first RS flip-flop to the plurality of first OR gates. Detects that one of the key switches is in a conductive state by generating an output,
The first and second key identification signal input terminals are sequentially driven to identify a key-switch that is in a conductive state, and the plurality of first keys are connected to one input terminal of the plurality of first OR gates. A second RS flip-flop is provided in part or all of the connection lines to which the identification signal input terminals are respectively connected, and the output terminal of the second RS flip-flop is connected to the first RS flip-flop.
and connect the set terminal to one input terminal of the OR gate, and connect the set terminal to the first key identification signal input terminal,
A key identification circuit characterized in that the reset terminal of the second RS flip-flop is connected to a fourth key identification signal input terminal.