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Touch sensing method and apparatus

A touch sensor and equipment technology, which is applied in the direction of transmitting sensing components, keyboard codes, instruments, etc. by using electric/magnetic devices, and can solve problems such as errors and low effective bits

Active Publication Date: 2014-05-14
TEXAS INSTR INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This means that if a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC) is used to digitize this measurement, the touch capacitance measurement may be limited to about 5 least significant bits
Therefore, errors due to noise are prone to occur
Also, the base capacitance may drift over time, which introduces further errors

Method used

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  • Touch sensing method and apparatus
  • Touch sensing method and apparatus
  • Touch sensing method and apparatus

Examples

Experimental program
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Embodiment Construction

[0025] figure 1 A system 100 is shown according to an exemplary embodiment. As shown, system 100 generally includes a touch panel 102 and a touch panel controller 104 . Touch panel 102 typically includes one or more touch sensors (eg, touch keys) arranged in various ways (ie, array or line), and touch panel controller 104 typically includes an interface or I / F 106, AFE 108 , a digital front end (DFE) 110 , a host controller 112 and a control logic 114 .

[0026] In operation, touch panel controller 104 is capable of detecting touch events on touch panel 106 . To accomplish this functionality, the touchscreen controller 104 is able to “scanthrough” or select the various touch sensors on the touch panel 102 . Scanning or selection is typically done with interface 106 (which may include a multiplexer) to allow the appropriate or selected touch sensor to be coupled to AFE 108 . Once coupled to the selected touch sensor via interface 106 , AFE 108 determines whether a touch eve...

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PUM

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Abstract

A method for measuring for generating a touch capacitance measurement is provided. Gain and offset control signals are generated, where the gain and offset control signals are adjusted to compensate for base capacitance of a touch sensor. The gain control signal is applied to a touch sensor during a first phase of a clock signal, and the offset control signal is applied to an output circuit during a second phase of the clock signal. The output circuit is coupled to the touch sensor during the second phase of the clock signal. The touch capacitance measurement is generated by compensating for the base capacitance with the gain and offset control signals, and a gain is applied to the touch capacitance measurement.

Description

technical field [0001] The present invention relates generally to capacitive touch sensors, and more particularly to sensing subtle changes in capacitive touch sensors. Background technique [0002] Capacitive touch sensors (such as touch buttons) are increasingly used in human-machine interface devices. These touch sensors typically have a base capacitance and operate based on detecting an increase in base capacitance due to the presence of a dielectric (ie, finger) close to the sensor. In the case of some touch sensors, this change or change in base capacitance (which may be referred to as touch capacitance) can be as little as 0.5%. This means that if a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC) is used to digitize this measurement, the touch capacitance measurement may be limited to about 5 least significant bits. Therefore, errors due to noise easily occur. In addition, the base capacitance may drift over time, which introduces f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F3/044G09G3/20
CPCG06F3/044G06F3/04182G01D5/24H03M11/02G01P15/125H03M3/34H03M3/458
Inventor S·阿拉斯T·倪黑A·拉赫曼
Owner TEXAS INSTR INC