Touch Detection Driver Circuit Continuous Sensing
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Solution Overview
Problem
Existing self-capacitance touch sensors require a two-step process to drive and sense electrodes, which is sequential and exclusive, limiting their ability to continuously detect touches and proximity.
Innovation Solution
A driver circuit incorporating an operational transconductance amplifier coupled with a current mirror allows for simultaneous and continuous driving and sensing of electrodes, enabling continuous touch detection by mirroring the current and processing changes in capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-step sequential process is used to drive and sense electrodes, then the device complexity is reduced, but the touch detection continuity is limited and settling time increases
Solution Approach 1:
The patent implements continuous touch detection by eliminating the sequential two-step process and enabling simultaneous drive and sense operations. The driver circuit continuously drives the electrode while the sensing circuit continuously senses capacitance changes, allowing uninterrupted touch detection without initialization delays or settling times.
Solution Approach 2:
The patent merges the drive and sense operations into a single simultaneous process. By combining these previously separate sequential operations into concurrent operations using a unified driver circuit architecture, the system achieves continuous detection without the time losses associated with switching between drive and sense modes.
2Device complexity
If sequential drive and sense operations are performed, then the circuit design is simpler, but the touch sensitivity is reduced
Solution Approach 1:
Continuous sensing operation allows the system to constantly monitor capacitance changes without interruption. This continuous monitoring improves touch sensitivity by capturing subtle capacitance variations that might be missed during transitions between sequential drive and sense phases, enabling more precise touch detection.
3Device complexity
If two-step sequential processing is used, then the device structure is simplified, but the detection speed is limited
Solution Approach 1:
The continuous operation mode eliminates the time required to switch between drive and sense phases. By maintaining uninterrupted drive and sense operations simultaneously, the system achieves faster detection response times compared to sequential processing where the system must wait for one phase to complete before initiating the next.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances touch sensitivity, allows for rail-to-rail sensing, and reduces output impedance, enabling efficient detection of touches and proximity without initialization delays or limited settling times.
Implementation Method 1
A driver circuit incorporating an operational transconductance amplifier coupled with a current mirror allows for simultaneous and continuous driving and sensing of electrodes
Implementation Method 2
enabling continuous touch detection by mirroring the current and processing changes in capacitance
Implementation Method 3
a change in capacitance may occur within the touch screen at a position of the touch sensor of the touch screen that corresponds to the position of the object within the touch sensitive area of the touch sensor
Data Source
AI summary
A method includes driving, by a first driver circuit, a current through an electrode and detecting, by a sensing system, a touch based on a change in capacitance at the electrode. The first driver circuit includes a first operational transconductance amplifier and a first current mirror. A second current mirror is coupled to the sensing system. A first switch is coupled to the first current mirror. A second switch is coupled to the first current mirror and the first operational transconductance amplifier. A third switch is coupled to the first operational transconductance amplifier and the second current mirror. A fourth switch is coupled to the second current mirror. A fifth switch is coupled to the first operational transconductance amplifier. A sixth switch is coupled to the first operational transconductance amplifier. A seventh switch is coupled to the first operational transconductance amplifier, the first current mirror, and the second current mirror.