JP2003271291A - Key scan device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease size of a device and reduce numbers of LSIs and signal lines in a key scan circuit. <P>SOLUTION: Each of terminals (7, 8 and 9) including keys (i and j) (1≤i≤m, 1≤j≤n) is connected in one case, and not connected in another case. Resistances (2 and 3) are connected with some of the terminals of the keys (i and j) in accordance with the state in which each terminal of each key is connected or not connected, so that combination for the connection may vary. Further, a power source VDD supplies a part of the resistance 3 with electric power. Then, a detecting means 6 detects electric characteristics which is generated in correspondence to the state in which each terminal of the key (i or j) is connected or not connected. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key scanning device for realizing a signal input / output interface generally required for scanning keys, which is generally mounted on electronic equipment, and more particularly to an ASIC (application specif).
ic integrated circuit) such as a key scan device that can minimize the input and output signals of integrated circuits.

[0002]

2. Description of the Related Art An input device having a plurality of keys is often mounted on an electronic device. A user inputs a particular command into the electronic device by pressing those keys located on the input device.

If the input device has a plurality of keys,
A key scanning device that performs a key scan to determine the key pressed by the user is essential. Normal,
The keys are arranged in a matrix according to the number of keys, and the keys are required in the number corresponding to the m × n matrix. That is, it is necessary to secure a large number of input / output interfaces in an integrated circuit such as an ASIC.

Further, processing such as scanning which key is pressed by the scan circuit inside the LSI, and a processing unit inside the LSI detecting which key is pressed by an interrupt signal from the scan circuit Is running.

Furthermore, as integrated circuits such as ASICs are made smaller, the miniaturization of chips and the miniaturization of packages are progressing.

[0006]

As described above, in the conventional key scanning device, the key scanning circuit and the interface for scanning the key to determine the depressed key, that is, the input / output interface with the integrated circuit such as ASIC. Are required in large numbers.

From the circuit portion where the key is arranged, L
Since the number of signal lines input to SI is large, it is difficult to downsize the key scanning device.

Further, since the circuits such as the scan circuit inside the LSI are large, it is difficult to miniaturize the LSI.

Further, in order to suppress the increase in the size of the device in which the key scanning device is mounted, it is necessary to reduce the parts, and the adoption of small parts leads to an increase in manufacturing cost.

In view of these problems in the prior art described above, the present invention provides a key scan device capable of reducing the size of the device and further reducing the number of signal lines of the LSI and the key scan circuit. The purpose is to

[0011]

A key scanning device according to the present invention has a plurality of terminals and is in a connected state in which the respective terminals are connected or in a non-connected state in which the respective terminals are unconnected. A plurality of keys which can be in the above state, and some of the respective keys so that the combination to be connected changes depending on whether the respective terminals of the respective keys are connected or not connected. Depending on whether a plurality of resistors connected to the terminals, a power source for supplying power to a part of the resistors, and the terminals of any one of the keys are connected. And a detection means for detecting the electrical characteristics generated by the above.

Further, the key scanning device of the present invention has a plurality of terminals and a connection state in which the respective terminals are connected,
And a plurality of keys that can be set to any one of the non-connection states in which the respective terminals are not connected, and the keys are connected depending on whether the respective terminals of the keys are in the connection state or the non-connection state. So as to change the combination, a plurality of resistors connected to some terminals of each of the keys, a constant voltage means for keeping one end of each of the resistors at a constant voltage, and one of the keys. Voltage value detecting means for detecting a voltage value based on the resistance according to whether or not each of the terminals of the key is in a connected state.

With the above arrangement, the interface for executing the key scan can be performed with a minimum of one line. In addition, the reduction in the number of interfaces can contribute to the miniaturization of the device and the miniaturization of the device and the progress of miniaturization of the package. Further, the voltage value based on the resistor can be assigned to each key individually by the arrangement of the resistor.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A key scanning device according to an embodiment of the present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a functional block diagram of a key scanning device according to an embodiment of the present invention. The key scanning device of this embodiment is
Keys (i, j) arranged in a matrix (1 ≦ i ≦ m,
1 ≦ j ≦ n; m and n are natural numbers. n = 1, 2, 3, ...
,), The resistor 2 arranged in the column direction, the resistor 3 arranged in the row direction, the resistor 4 grounded, and LS.
It is provided with an A / D converter (analog-digital converter) 6 in I5 and a power supply VDD. Here, the row direction refers to the left and right directions in FIG. 1, and the column direction refers to FIG.
Shows the vertical direction.

Each key (i, j) has three terminals, and when the key (i, j) is pressed, the key (i, j)
All the terminals of j) become conductive. On the contrary, when the key (i, j) is released, all the terminals of the key (i, j) become non-conductive. In the present embodiment, the key (i,
j) are regularly arranged in a matrix and m in a square shape.
× n keys (i, j) are arranged.

The resistor 2 arranged in the column direction has one end in the middle of all the keys (i, j) arranged in the row direction of the resistor 2, that is, the key (i, j) in FIG. It is connected to the second terminal 8 shown.

For example, Rci (1.ltoreq.i.ltoreq.m) is connected to the second terminal 8 of the key (i, 1) arranged immediately to the right, and further the second terminal of the key (i, 1). 8 is connected to the second terminal 8 of the key (i, 2) located immediately to the right. That is, from Rci and (i, 1) to (i, n)
Up to the second terminals 8 of the n keys are connected.

The other end of the resistor 2 arranged in the column direction is grounded. In the above example, another terminal other than the terminal connected to the Rci key (i, 1) is grounded.

The resistor 3 arranged in the row direction has one end of all the keys (i, j) arranged in the column direction of the resistor 3, unlike the case of the resistor 2, the key (i, j). )
Is connected to the third terminal 9 shown on the right.

For example, Rrj (1.ltoreq.j.ltoreq.n) is connected to the third terminal 9 of the key (1, j) disposed immediately below, and the third terminal of the key (1, j) is further connected. 9 is connected to the third terminal 9 of the key (2, j) located immediately below it. That is, from Rrj and (1, j) to (m, j)
Up to m keys of the third terminal 9 are connected.

The other end of the resistor 3 arranged in the row direction is connected to the power supply VDD. The power supply VDD is a constant voltage source. In the above example, another terminal different from the terminal connected to the key (1, j) is connected to the power supply VDD.

The first terminal 7 of the key (i, j) is connected to the A / D converter 6 and the resistor 4. The resistor 4 is for discharging electric charges that may be accumulated in the first terminal 7.

Resistor 4 includes resistors Rci and R arranged in the column direction and the row direction shown in FIG. 1, respectively.
It is set to have a sufficiently large value as compared with rj (1 ≦ i ≦ m, 1 ≦ j ≦ n). In other words, for the resistors Rci and Rrj (1 ≦ i ≦ m, 1 ≦ j ≦ n), the resistor 4 has the effect of insulating the outside world from the first terminal 7 of each key.

The A / D converter 6 detects the voltage value on the signal line connecting the first terminals 7 of all the keys (i, j). Based on this voltage value, the LSI5
The (largescale integrated circuit) can detect which key is pressed. That is, when the key (i, j) (1 ≦ i ≦ m, 1 ≦ j ≦ n) is pressed, a voltage value uniquely determined by the resistance Rci and the resistance Rrj is input to the A / D converter 6. In Figure 1,
Although only one A / D converter is installed, two or more A / D converters may be installed and connected to the first terminal 7 of a predetermined key (i, j). For example, the keys in the upper half of FIG. 1 may be connected to the first A / D converter, and the keys in the lower half may be set to be connected to the second A / D converter.

In this case, since the resistance value may be set in the circuit connected to each A / D converter, the number of voltage values that the A / D converter needs to identify is reduced. Therefore, the possibility that more accurate voltage value detection can be realized increases.

Further, in this case, it is possible to reduce the resistance value to half by finely setting the resistance value. Furthermore, since it is possible to have the same circuit configuration on the top and bottom,
As the resistors arranged in the column direction, resistors having the same resistance value can be used. Therefore, it is not necessary to prepare many resistors having different resistance values.

Further, instead of the A / D converter 6 for measuring the voltage value, a detector for measuring the current value may be arranged. The A / D converter 6 may be any device as long as it can detect electrical characteristics that change when a key is pressed, that is, a change in voltage value, current value, or the like.

FIG. 2 is an enlarged view of a portion including four keys at the upper left of FIG. FIG. 3 is a diagram showing voltage values detected by the A / D converter when each of the keys shown in FIG. 1 is pressed alone. In FIG. 3, the voltage value of the power supply VDD is 1 for simplicity. When the voltage value of VDD is V, V may be applied to the value of each item in which the voltage value is described. The operation when the key is actually pressed will be described in detail below. Key (i, j) (1 ≦ i ≦
When m, 1 ≦ j ≦ n) is pressed, the voltage value of the first terminal 7 of the key (i, j) becomes equal to the voltage value between Rci and Rrj. When the key (i, j) is pressed, one end of Rci is grounded and the other end is connected to the first terminal 7 and one end of Rrj. Further, the other end of Rrj is connected to the power supply VDD.

Therefore, the first terminal 7 of the key (i, j)
The voltage value of is V times Rci / (Rci + Rrj). When only the key (i, j) is pressed, this voltage value is detected by the A / D converter 6. For example,
If the key (1,1) is pressed, the first key of the key (1,1)
The voltage value of the terminal 7 becomes Rc1 / (Rc1 + Rr1).
If the key (1, 2) is pressed, the key (1, 2)
The voltage value of the first terminal 7 becomes Rc1 / (Rc1 + Rr2).

Rci and Rrj (1≤i shown in FIG. 3
Rci / (Rci + Rr) consisting of ≦ m and 1 ≦ j ≦ n)
Adjust all Rci and Rrj so that j) are all different values. As a result, if the pressed key is different, the voltage value detected by the A / D converter 6 is also different. Therefore, in this case, if the voltage value detected by the A / D converter 6 is applied to the table shown in FIG. 3, the LSI 5 can determine which key is pressed.

As a further development, even if some of the keys are pressed at the same time, if it is necessary to enable the pressing of the keys, the A / D converter 6 detects the pressing of those keys. The voltage value of Rci /
The resistance values Rci and Rrj (1 ≦ rci + Rrj) (1 ≦ i ≦ m, 1 ≦ j ≦ n) are different from each other.
i ≦ m, 1 ≦ j ≦ n) is adjusted.

As a result, when a key that is supposed to be pressed is pressed, it is possible to reliably determine which key is pressed.

Further, the resistance value may be set in consideration of all cases in which there is a possibility of being further developed and being pressed. In this case, if the user mistakenly performs a meaningless key operation, a warning sound or a warning display is displayed on the C screen.
It is also possible to set to output to a speaker, a screen, etc. through PU.

The key scanning device according to the above-described embodiment enables an interface for executing a key scan with a minimum of one line. In addition, since the size of the interface can be reduced, the LS is becoming smaller and smaller as the size and weight of the device are reduced.
I can also contribute greatly. (Comparative example) FIG.
FIG. 2 is a functional block diagram of a key scanning device for comparison with the key scanning device according to the embodiment shown in FIG. 1. In FIG. 4, the key has two terminals.

The key scanning device shown in FIG.
The key [i, j] (1 ≦ i ≦ m, 1 ≦ j ≦ 2), the resistor 12 arranged in the column direction, the resistor 13 arranged in the row direction, and the resistor 13 arranged in the LSI 5. It is equipped with an A / D converter 6-k (1 ≦ k ≦ m) and a power supply VDD.

Each key [i, j] is the same as the key of the key scanning device according to the embodiment of the present invention shown in FIGS. 1 and 2, except that it has two terminals. Further, the resistors 12 arranged in the column direction are also arranged in the same manner as the resistors 2 of the key scan device according to the above-described embodiment.

The resistors 12 arranged in the column direction are connected to the first terminals 14 of the keys [i, j]. The first terminal 14 is shown to the left of the key [i, j] in FIG.

The resistors 13 arranged in the row direction are connected to the second terminal 15 of each key. The second terminal 15 is shown to the right of the key [i, j] in FIG. In the example of FIG. 4, as compared with the above-described embodiment, the number of terminals to be arranged increases because the key has only two terminals.

That is, in the example of FIG. 4, when the numbers of resistors in the same number of keys, 2n, are compared, the number of resistors in the row direction becomes n times. Furthermore, the length of the signal line connecting to the key may increase according to the increased resistance number.

Further, the A / D converter 6-k (1≤k≤
m) also needs to be connected for each resistor 12 arranged in the column direction. This also has only two terminals for the keys [i, j]. Therefore, if the connections of the resistors 12 arranged in the column direction are connected, the resistors 12 arranged in all the column directions have voltage values. Therefore, the possibility that the A / D converter cannot detect the voltage value increases. With this, it becomes impossible to detect the voltage value by the pressed key, so that it is necessary to arrange the A / D converters by the number of the resistors 12 arranged in the column direction. Since the A / D converter occupies a large area in the LSI, the A / D converter is connected to the resistor 12 like this.
If the number of the above is arranged, the chip area is increased. An increase in chip area leads to an increase in cost.

On the other hand, the key scanning device according to the embodiment of the present invention shown in FIGS. 1 to 3 can be completed with only one A / D converter. In addition, since the keys can be arranged in a matrix, the required resistance can be minimized. Therefore, the mounting area can be reduced and the manufacturing cost can be suppressed.

The present invention is applicable to any device as long as it is a device for electrically sending a signal to an LSI or the like to transmit a command to a CPU or the like by pressing a specific key or the like. For example, keyboard, telephone input device,
It can be used for a remote controller or the like. In particular, it is effective for a device in which the transmission path between the circuit of the key part and the LSI is limited.

The present invention is not limited to the above-described embodiments, but can be implemented with various modifications within the technical scope thereof.

[0044]

According to the key scan device of the present invention, the size of the device can be reduced and the number of signal lines with the LSI can be reduced.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a key scanning device according to an embodiment of the present invention.

FIG. 2 is an enlarged view in which a part including four keys at the upper left of FIG. 1 is enlarged.

FIG. 3 is a diagram showing a voltage value detected by an A / D converter when each key shown in FIG. 1 is pressed alone.

4 is a functional block diagram of a key scanning device for comparison with the key scanning device according to the embodiment shown in FIG. 1. FIG.

[Explanation of symbols]

2 resistance 3 resistance 4 resistance 5 LSI 6 converter 7 First terminal 8 second terminal 9 3rd terminal 12 resistance 13 resistance 14 First terminal 15 Second terminal

Claims (10)

[Claims] 1. A plurality of keys that have a plurality of terminals and can be in any one of a connected state in which the respective terminals are connected and a non-connected state in which the respective terminals are not connected And a plurality of resistors connected to some terminals of each of the keys so that the combination to be connected changes depending on whether the terminals of each of the keys are connected or not connected, A power supply that supplies power to a part of each of the resistors, and a detection unit that detects an electrical characteristic that occurs depending on whether or not the terminals of any of the keys are in a connected state, A key scanning device comprising: 2. The resistance value of each resistor is set so that the key in the connected state among the keys and the value of the electrical characteristic detected by the detection means in this case correspond to each other. The key scanning device according to claim 1, wherein the key scanning device is a key scanning device. 3. The key scanning device according to claim 1, wherein the detection means is connected to a terminal of the keys that is not connected to a resistor. 4. The detection means is connected to one of the terminals of each of the keys, which is not connected to a resistor, by one signal line. Key scanning device. 5. The power source is connected to one end of one of the resistors connected to each key, and the other end of the resistors connected to each of the keys is grounded. The key scanning device according to any one of claims 1 to 4. 6. A plurality of keys having a plurality of terminals and capable of being in any one of a connected state in which the respective terminals are connected and a non-connected state in which the respective terminals are not connected And a plurality of resistors connected to some terminals of each of the keys so that the combination to be connected changes depending on whether the terminals of each of the keys are connected or not connected, A constant voltage means for keeping one end of each resistor at a constant voltage, and a voltage for detecting a voltage value based on the resistor according to whether or not each terminal of any one of the keys is in a connected state. A key scanning device comprising: a value detecting unit; 7. The resistance value of each of the resistors is set so that the key in the connected state of the keys and the voltage value detected by the detection means in this case correspond to each other. The key scanning device according to claim 6. 8. The key scanning device according to claim 6, wherein the voltage value detection means is connected to a terminal of the terminals of each key that is not connected to a resistor. 9. The voltage value detecting means is connected to one of the terminals of each of the keys, which is not connected to a resistor, by one signal line.
Key scanning device described in. 10. One of resistors connected to each key.
10. The constant voltage means is connected to one end of one resistor, and one end of the other resistor connected to each of the keys is grounded. Key scanning device.