Touch Sensing System Power Management via Grouped Unit Segmentation
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Solution Overview
Problem
Capacitive touch sensing systems for medium and large-sized devices face challenges in reducing power consumption during idle states due to the large number of driving units and sensing units, which affects touch sensitivity and driving performance.
Innovation Solution
The system divides sensing units and analog-to-digital converters into groups, powering down some units while keeping others active to conserve power without compromising touch sensitivity, by sequentially activating groups and units in an idle state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sensing units and driving units is increased to support medium and large-sized touch screens, then the touch sensitivity and driving performance are improved, but the power consumption increases significantly
Solution Approach 1:
The touch screen is divided into multiple zones with different sampling frequencies. High-resolution sampling is applied only to zones where touch input is detected, while low-resolution sampling is applied to other zones. This segmentation allows the system to maintain high touch sensitivity where needed while reducing power consumption in inactive areas.
Solution Approach 2:
The sampling frequency of each zone is dynamically adjusted based on touch activity. When a touch is detected in a particular zone, that zone transitions to high-frequency sampling mode. When no touch is detected, the zone transitions to low-frequency sampling mode. This dynamic adaptation resolves the contradiction between maintaining high touch sensitivity and reducing power consumption.
2Use of energy by moving object
If the driving velocity is reduced to lower power consumption in idle state, then the power consumption is reduced, but the touch report rate and sensing velocity decrease
Solution Approach 1:
The system implements periodic sampling with variable frequencies across different zones. Instead of continuous high-frequency sampling across the entire screen, the system performs sampling at different periodic intervals based on zone activity. This periodic action with adaptive frequencies maintains the necessary touch report rate while significantly reducing power consumption during idle states.
Solution Approach 2:
The system applies full sampling frequency only to the minimal necessary portions of the screen where touch activity occurs, rather than maintaining full frequency across the entire display. This partial action approach ensures adequate touch reporting performance is maintained where needed while avoiding excessive power consumption in inactive regions.
Data Source
AI summary
A touch sensing system and a method of controlling power consumption thereof are disclosed. The touch sensing system includes a plurality of sensing units, which sample a voltage received from a touch screen and accumulate the sampled voltage, and a plurality of analog-to-digital converters converting an output of the sensing units into digital data. The sensing units and the analog-to-digital converters are divided into a plurality of groups in an idle state. Each of the plurality of groups includes at least two sensing units and one analog-to-digital converter. At least one sensing unit included in at least one group is powered down in the idle state. An analog-to-digital converter is powered on during the group it belongs to is powered on.