KR100631503B1 - Keypad apparatus for telephone - Google Patents

Abstract

The present invention relates to a technology that simplifies the circuit configuration of a keypad applied to a telephone and the like, and enables the controller to easily recognize which key signal is input without additional processing. The present invention includes a pull-up resistor unit 41 for supplying each divided voltage to each input port of the microcomputer 43 using a plurality of pull-up resistors connected in series; A key matrix 42 for connecting two different connection points of the pull-up resistors to the ground terminals in common as each key is pressed; It is achieved by the microcomputer 43 which scans which input port of the plurality of input ports a signal of "ground potential" level is input and determines which key signal is input based on the scanning result.

Description

Keypad Device for Phones {KEYPAD APPARATUS FOR TELEPHONE}

1 is a circuit diagram of a keypad of a conventional telephone.

2 is another exemplary diagram of a keypad of a conventional telephone.

3 is a timing pulse waveform diagram of a microcomputer in FIG.

4 is an exemplary circuit diagram of a keypad device of a telephone according to the present invention.

*** Description of the symbols for the main parts of the drawings ***

41: pull-up resistor 42: key matrix

43: microcomputer

The present invention relates to a design technology of a keypad applied to a telephone, and more particularly, to simplify the circuit configuration of the keypad, and to allow the controller to easily recognize which key signal is input without additional processing. It is about.

1 is a keypad circuit diagram of a conventional telephone according to the related art. As shown therein, resistors R1-R3 are connected in series between a power supply terminal VCC and a ground terminal, and a connection point of the resistors R1-R3 is shown. A keypad 11 to which respective keys KEY1-KEY3 are connected between the ground terminals; An A / D converter 12 for converting an analog voltage output at a different level into a digital signal in response to each key (KEY1-KEY3) being pressed on the keypad 11; Based on the output voltage of the A / D converter 12, it is composed of a microcomputer 13 that performs a corresponding function by determining which key signal is input. The operation thereof will be described as follows.

First, referring to the keypad 11, the resistors R1-R3 are connected in series between the power supply terminal VCC and the ground terminal, and each key (B) between the connection point of the resistors R1-R3 and the ground terminal is connected. KEY1-KEY3) is connected.

Therefore, when the key KEY1 is pressed, the ground potential is supplied to the A / D converter 12 through the resistor R0, and when the key KEY2 is pressed, the connection point potential of the resistor R1 and the resistor R2 is the resistor. The A / D converter 12 is supplied to the A / D converter 12 through R0, and when the key KEY3 is pressed, the connection point potential of the resistor R1 and the resistors R2 and R3 is connected to the A / D converter 12 through the resistor R0. Is supplied.

The A / D converter 12 converts an analog voltage input at a different level into a digital signal as the respective keys KEY1-KEY3 are pressed on the keypad 11, and outputs the digital signal. The digital computer 13 outputs the digital signal. Based on the signal, which key is pressed among the keys KEY1-KEY3, that is, which key signal is input, the corresponding control function is performed.

On the other hand, Figure 2 shows another example of a telephone keypad according to the prior art. That is, FIG. 2 is a matrix keypad using a timing signal, and its operation will be described with reference to FIG. 3.

The microcomputer 22 outputs a timing pulse as shown in FIG. 3 with a predetermined time difference in its output ports P11-P13, and at this time, scans the input port P21 and selects one of the keys KEY1-KEY3. Determine if it is pressed.

For example, a pulse is output to the output port P11 at the timing as shown in FIG. 3A, and when it is detected that a "high" signal is input to the input port P21, it is determined that the key KEY1 is pressed. do. Similarly, a pulse is output to the output port P12 at the timing as shown in FIG. 3 (b), and when it is detected that a "high" signal is input to the input port P21, it is determined that the key KEY2 is pressed. . Similarly, a pulse is output to the output port P13 at the timing as shown in FIG. 3C. At this time, when it is detected that a "high" signal is input to the input port P21, it is determined that the key KEY3 is pressed. .

 However, in the conventional keypad such as the former, a large number of resistors are required as well as an A / D converter, so that the configuration is complicated and the cost increases. In addition, in the latter conventional keypad, since a timing pulse for recognizing a key signal must be output from the microcomputer, the result is a burden on the microcomputer, which makes it difficult to faithfully perform the original function.

Accordingly, an object of the present invention is to provide a keypad device having a simple configuration so that the control unit can easily determine the input key signal without any processing.

The first feature of the present invention is to minimize the number of resistors used in the keypad.

A second feature of the invention is that the controller does not require additional processing such as timing processing.

According to a third aspect of the present invention, the controller may determine which key signal is input by checking a change in logic value of each input port.

FIG. 4 is a block diagram illustrating an exemplary keypad device for a telephone according to the present invention. As shown therein, a pull-up resistor R1-R3 is connected in series to a power supply terminal VCC, and the pull-up resistor R1- is connected. Pull-up resistor sections 41 each connecting the connection points N1-N3 of R3 to the input ports P1-P3 of the microcomputer 43, which will be described later; Key matrix 42 for connecting the connection points N1, N2, N1, N3, and N2, N3 to ground terminals in common according to the pressing of each key KEY1, KEY2, and KEY3. Wow; Scans which of the input ports P1-P3 is input to the "ground potential" level, and determines which key signal is input from the key matrix 42 based on the scanning result, thereby controlling the corresponding control function. It is configured as a microcomputer 43 to perform the operation of the present invention configured as described in detail as follows.

First, when the pull-up resistor unit 41 is examined, the pull-up resistors R1-R3 connected in series are connected to the power supply terminal VCC, and each connection point N1-N3 of the resistors R1-R3 is micro. It is connected to the input ports P1-P3 of the computer 43, respectively.

On the other hand, the connection points N1 and N2 are respectively connected to two fixed terminals of the key KEY1, and the movable terminal of the key KEY1 is connected to the ground terminal. Therefore, when the key KEY1 is pressed, the connection points N1 and N2 are connected to the ground terminal through the key KEY1.

The connection points N1 and N3 are connected to two fixed terminals of the key KEY2, respectively, and the movable terminal of the key KEY2 is connected to the ground terminal. Therefore, when the key KEY2 is pressed, the connection points N1 and N3 are connected to the ground terminal through the key KEY2.

The connection points N2 and N3 are respectively connected to two fixed terminals of the key KEY3, and the movable terminal of the key KEY2 is connected to the ground terminal. Therefore, when the key KEY3 is pressed, the connection points N2 and N3 are connected to the ground terminal through the key KEY3.

Therefore, when the keys KEY1-KEY3 are not all pressed in the key matrix 42, the voltages sequentially divided by the resistors R1-R3 are respectively applied to the input ports P1-P3 of the microcomputer 43. Is entered. At this time, the microcomputer 43 confirms that a voltage of a predetermined level or more is supplied to the input ports P1-P3, and determines that no key is pressed among the keys KEY1-KEY3. That is, it is determined that no key signal is input.

However, when the key KEY1 is pressed by the user, as described above, the connection points N1 and N2 are connected to the ground terminal through the key KEY1, so that the input of the microcomputer 43 is performed. Ground potentials are supplied to ports P1 and P2. Therefore, the microcomputer 43 scans that the ground potential is input to the input ports P1 and P2, and determines that the current key KEY1 is pressed.

In addition, when the key KEY2 is pressed by the user, as described above, the connection points N1 and N3 are connected to the ground terminal through the key KEY2, so that the input of the microcomputer 43 is performed. Ground potentials are supplied to ports P1 and P3. Accordingly, the microcomputer 43 scans that the ground potential is input to the input ports P1 and P3 and determines that the current key KEY2 is pressed.

In addition, when the key KEY3 is pressed by the user, the connection point N2, N3 is connected to the ground terminal through the key KEY3 as described above, so that the input of the microcomputer 43 is performed. Ground potentials are supplied to ports P2 and P3. Accordingly, the microcomputer 43 determines that the current key KEY3 is pressed by scanning that the ground potential is input to the input ports P2 and P3.

In the above description, three keys (KEY1-KEY3) have been described as an example. However, when additional keys are added, a series resistor may be added to the connection point N3 and an input port of the microcomputer may be added accordingly.

As described in detail above, the present invention connects each connection point of the pull-up resistor to the input port of the microcomputer, and also connects two different connection points to the ground terminal through the respective keys, and in the microcomputer, any input port. By scanning whether a signal having a ground potential level is input to the terminal and determining the input key signal based on the scanning result, the configuration of the keypad is simplified, and the microcomputer side can easily judge the input key signal without any processing. The cost savings are effective.

Claims (3)

A pull-up resistor unit for supplying each divided voltage to each input port of the microcomputer using a plurality of pull-up resistors connected in series; A key matrix for connecting two different connection points of the pull-up resistors to the ground terminals in common as each key is pressed; A keypad apparatus for a telephone, comprising: a microcomputer configured to scan which input port of a plurality of input ports a signal of a "ground potential" level is input and determine which key signal is input based on the scanning result. The pull-up resistor unit connects the pull-up resistors R1-R3 to the power supply terminal VCC, and connects the connection points N1-N3 between the resistors R1-R3 to the input port of the microcomputer. Keypad device of a telephone, characterized in that configured to connect to each of P1-P3). The key matrix of claim 1, wherein each of the connection points (N1, N2), (N1, N3), (N2, N3) between the pull-up resistors R1-R3 of the pull-up resistor unit is selected from each of the keys (KEY1-KEY3). Keypad device of a telephone, characterized in that configured by connecting to the ground terminal through.

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