Single-Node Channel Driver Circuit for Fast Touch Sensing
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Solution Overview
Problem
Projected capacitive touch sensors face challenges in accurately determining touch locations due to large parasitic capacitances, which require multiple integration cycles, increasing the time to make a determination and affecting user experience, especially in larger displays.
Innovation Solution
A channel driver circuit that employs a differential module, sigma-delta module, and driver module to generate a low impedance virtual signal and receive load-modified signals, while simultaneously detecting changes, using noise shaping to reduce noise and improve signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple integration cycles are used to overcome parasitic capacitance effects, then measurement precision improves, but response time increases
Solution Approach 1:
The patent changes the integration cycle parameter from multiple cycles to a single integration cycle, achieving both fast response time and accurate touch location detection by optimizing the integration process rather than repeating it multiple times
2Loss of time
If a single integration cycle is used, then response time decreases, but measurement precision deteriorates due to parasitic capacitance
Solution Approach 1:
The patent implements feedback mechanisms that allow accurate touch location detection in a single integration cycle by continuously monitoring and adjusting for parasitic capacitance effects, eliminating the need for multiple integration cycles
Solution Approach 2:
The patent optimizes circuit parameters and integration methodology to achieve high measurement precision with minimal integration time, fundamentally changing the approach from repeated integration to a single optimized integration cycle
Data Source
AI summary
A channel driver circuit includes a differential module and a driver module. In some examples, the channel driver circuit also includes a sigma-delta module. The differential module receives, via a single node of a load, a channel driving signal that is provided to the load at the single node (e.g., that is based on an electrical characteristic of the load) and generates an analog error signal that is based on the channel driving signal and a reference signal. The driver module is coupled to the differential module and generates the channel driving signal based on the analog error signal or a digital error signal corresponding to the analog error signal and transmits the channel driving signal via the single node to the load. The channel driver circuit simultaneously transmits the channel driving signal to the load at the single node and senses the channel driving signal at the single node.