Key input device
A key input device for data input means of a device is provided. The key input device includes a first terminal for outputting a key input signal, a second terminal spaced apart from the first terminal and having at least two divided parts, wherein all the divided parts contact the first terminal during a key input operation, at least one resistor allocated to each of the divided parts of the second terminal, connected in parallel to each other, and having respectively different resistance values, and a processor chip for controlling a corresponding key input operation according to respectively different voltage values outputted from the first terminal, by at least one corresponding resistor that is electrically and selectively connected to each of the divided parts.
1. A key input device for data input, comprising:
a first terminal for outputting a key input signal;
a second terminal spaced apart from the first terminal and having at least two divided parts, wherein all the divided parts contact the first terminal during a key input operation;
at least one resistor allocated to each of the divided parts of the second terminal, connected in parallel to each other and having respectively different resistance values; and
a processor chip controlling a corresponding key input operation according to respectively different voltage values outputted from the first terminal, by at least one corresponding resistor that is electrically and selectively connected to each of the divided parts.
2. The key input device of claim 1 , wherein the processor chip further comprises an Analog-Digital Convertor (ADC) port for digitalizing an analog signal outputted from the first terminal and delivering it to the processor chip.
3. The key input device of claim 2 , wherein the processor chip codes a key input signal inputted to the ADC port and controls to output a corresponding key value for a predetermined corresponding voltage value.
4. The key input device of claim 1 , wherein the second terminal is equally divided.
5. The key input device of claim 3 , wherein the number of the corresponding key values is the maximum number of patterns derived from the following equation according to the n number of divided second terminals,
∑
i
=
1
n
C
i
n
=
Maximum
number
of
patterns
.
6. The key input device of claim 1 , wherein the first terminal and the second terminal are disposed on a Printed Circuit Board (PCB).
7. The key input device of claim 6 , further comprising a dome sheet on the top surfaces of the first terminal and the second terminal as a key input switch, the key input switch connecting electrically and selectively the first terminal with each of the divided parts of the second terminal according to a pressurizing operation.
8. The key input device of claim 7 , wherein the first terminal and the second terminal are carbon contact pads.
9. The key input device of claim 7 , wherein when the dome sheet presses the second terminal to contact the first terminal, each divided part of the second terminal is electrically connected to the first terminal by a different resistance value.
10. The key input device of claim 3 , wherein the processor chip confirms which key is pressed using a process recognizing a voltage output from the first terminal and converting it into a code through the ADC port connected to the first terminal.
11. The key input device of claim 1 , wherein the first terminal is spaced a predetermined distance from the second terminal.
12. The key input device of claim 1 , wherein the first terminal is spaced from and disposed inside the second terminal of a hollow type.
13. The key input device of claim 1 , wherein the second terminal is spaced from and disposed inside the first terminal of a hollow type.