Touch Sensor and Signal Generation Method Thereof

• US 20080204422A1
• Filed: 05/17/2006
• Published: 08/28/2008
• Est. Priority Date: 06/16/2005
• Status: Active Grant

• Current Assignee: ATLab, Inc.
• Original Assignee: ATLab, Inc.
• Inventors: Moon, Byung-Joon, Hong, Jae-Surk
• Granted Patent: US 7,956,850 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/94031 Calibration involving digital processing
• CPC Class Codes: H03K 2217/960715 Rc-timing; e.g. measurement of variation of charge time or discharge time of the sensor

Abstract

A touch sensor and a signal generation method thereof are provided. The touch sensor includes: an input signal generation unit generating an input signal; a reference signal generation unit delaying the input signal by a predetermined time to generate a first signal; a plurality of touch sensing signal generation units having a touch pad and delaying the input signal differently according to whether or not the touch pad is touched to generate a second signal; a plurality of variable delay units varying a delay time in response to a control signal and delaying the second signal in response to the varied delay time to generate a varied second signal; a plurality of touch signal generation units generating a touch signal according to a difference in delay time between the first signal and the second signal; and a control unit receiving and analyzing the plurality of touch signals, generating touch outputs when the touch pad is in a touched state, and supplying the control signals to the variable delay units when the touch pad is in a standby state. Accordingly, the delay value may be automatically adjusted even when the delay value, which has been initially set, is varied due to an external environment, so that the touch pad may be prevented from being mis-operated.

Claims

1. A touch sensor, comprising:

an input signal generation unit generating an input signal;

a reference signal generation unit delaying the input signal by a predetermined time to generate a first signal;

a plurality of touch sensing signal generation units having a touch pad and delaying the input signal differently according to whether or not the touch pad is touched to generate a second signal;

a plurality of variable delay units varying a delay time in response to a control signal and delaying the second signal in response to the varied delay time to generate a varied second signal;

a plurality of touch signal generation units generating a touch signal according to a difference in delay time between the first signal and the second signal; and

a control unit receiving and analyzing the plurality of touch signals, generating touch outputs when the touch pad is in a touched state, and supplying the control signals to the variable delay units when the touch pad is in a standby state.

2. The touch sensor according to claim 1, wherein the reference signal generation unit has a plurality of serially connected inverters.

3. The touch sensor according to claim 1, wherein the reference signal generation unit has a capacitor connected to a ground voltage.

4. The touch sensor according to claim 1, wherein each of the touch sensing signal generation units generates the second signal by delaying the input signal longer than the first signal when the touch pad is in a touched state and delaying the input signal shorter than the first signal when the touch pad is not in a touched state.

5. The touch sensor according to claim 1, wherein each of the variable delay units has a plurality of delay components and receives the control signals from the control unit so that some of the delay components are activated in response to the control signals, and delays the second signals by delay times of the activated delay components to output the varied second signals.

6. The touch sensor according to claim 5, wherein each of the delay components has a multiplexer outputting one of two inputs in response to the control signals, and a plurality of inverters receiving an output of the multiplexer as an input and delaying the input by a predetermined time to output the input.

7. The touch sensor according to claim 1, wherein each of the touch signal generation units is a flip-lop which latches the varied second signal in response to the first signal and generates the touch signal.

8. The touch sensor according to claim 1, wherein each of the touch signal generation units is a flip-flop which latches the first signal in response to the varied second signal and generates the touch signal.

9. The touch sensor according to claim 1, wherein in the standby state, the control unit holds the most recent touch output until adjustment of the control signal for all of the touch pads is completed.

10. The touch sensor according to claim 9, wherein the control unit sequentially supplies the control signals to the respective variable delay units while the touch pad is not in the touched state.

11. The touch sensor according to claim 5, wherein the control unit obtains the control signal as minimum delay value when a value of the touch signals becomes a value indicating that the touch pad is in the touched state, and calculates differences between the minimum delay value and a sensitivity of the touch pad to determine a control value of the control signals.

12. A method of generating a touch signal of a touch sensor, comprising:

generating an input signal;

delaying the input signal by a predetermined time to generate a first signal;

delaying the input signal differently according to whether a touch pad is touched to generate a second signal;

varying a delay time in response to a control signal and delaying the second signal in response to the varied delay time to generate a varied second signal;

generating a touch signal according to a difference in delay time between the first signal and the second signal; and

receiving and analyzing the touch signal, generating a touch output when the touch pad is in a touched state, and adjusting the control signal when the touch pad is in a standby state.

13. The method according to claim 12, wherein adjusting the control signal comprises:

holding the most recent touch outputs in the standby state, varying the control signal, and receiving the touch signal to obtain a minimum delay value; and

adjusting the control signal using the obtained minimum delay value.

14. The method according to claim 13, wherein obtaining the minimum delay value comprises:

obtaining the control signal as the minimum delay value when a value of the touch signal becomes a value indicating that the touch pad is in a touched state while varying the control signal.

15. The method according to claim 13, wherein adjusting the control signal comprises:

checking whether the adjustment of the control signal is performed when the touch pad is in a non-touched state;

determining a control value using the obtained minimum delay value, and generating the determined control value as a control signal upon determination that the adjustment is performed when the touch pad is in the non-touched state; and

releasing the holding of the touch output upon determination that the adjustment is not performed when the touch pad is in the non-touched state.

16. The method according to claim 13, wherein adjusting the control signal further comprises:

releasing the holding of the touch output when the adjustment of the control signal is completed.

17. The method according to claim 15, wherein the control value is determined by calculating a difference between the minimum delay value and a touch sensitivity of the touch pad.