Coarse Scan and Targeted Active Mode Scan for Touch
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Solution Overview
Problem
Touch sensitive devices consume significant power due to continuous scanning for touch or proximity events, even when no objects are present, leading to battery drain and inefficiency.
Innovation Solution
Implementing a coarse scan, such as a banked common mode scan, to detect the presence or absence of touch events, and dynamically adjusting the operation to perform or skip fine scans based on the results, reducing power consumption by idling unused sense channels and reallocating scan time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous fine scan is performed to detect touch events, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The scanning process is divided into two distinct segments: a coarse scan that divides the touch panel into regions to detect general touch presence, and a fine scan that performs detailed detection only in regions where touches are detected. This segmentation allows the system to reduce overall scanning operations while maintaining detection precision where needed.
Solution Approach 2:
Instead of performing a complete fine scan across the entire touch panel continuously, the system performs partial scanning by conducting fine scans only in specific regions where touches are detected during the coarse scan phase. This partial action significantly reduces power consumption while maintaining detection precision for actual touch events.
2Speed
If continuous fine scan is performed to ensure responsiveness, then speed is improved, but use of energy increases
Solution Approach 1:
The system implements periodic coarse scans at lower power consumption levels, followed by conditional fine scans only when touches are detected. This periodic alternating pattern maintains system responsiveness by regularly checking for touches while consuming significantly less power than continuous fine scanning would require.
3Use of energy by moving object
If coarse scan is used to reduce power consumption, then use of energy is improved, but measurement precision deteriorates
Solution Approach 1:
The detection process is segmented into two stages: initial coarse scanning for low-power touch presence detection, followed by targeted fine scanning for precise touch location and characterization. This segmentation allows the system to use low-power coarse scanning most of the time while maintaining high precision when actual touches occur.
Solution Approach 2:
The coarse scan acts as an intermediary between the low-power state and the high-precision fine scan. It detects potential touch regions and triggers fine scans only when necessary, serving as a power-efficient mediator that maintains overall system precision while reducing average power consumption.
4Adaptability or versatility
If dynamic scanning adjustment is implemented, then adaptability is improved, but device complexity increases
Solution Approach 1:
The system uses feedback from coarse scan results to dynamically adjust the scanning strategy. When touches are detected in specific regions, the system automatically triggers fine scans in those regions; when no touches are detected, fine scans are skipped. This feedback mechanism provides adaptability while keeping control logic relatively simple through clear conditional rules.
Data Source
AI summary
Power consumption of touch sensing operations for touch sensitive devices can be reduced by implementing a coarse scan (e.g., banked common mode scan) to coarsely detect the presence or absence of an object touching or proximate to a touch sensor panel and the results of the coarse scan can be used to dynamically adjust the operation of the touch sensitive device to perform or not perform a fine scan (e.g., targeted active mode scan). In some examples, the results of the coarse scan can be used to program a touch controller for the next touch sensing frame to idle when no touch event is detected or to perform a fine scan when one or more touch events are detected. In some examples, the results of the coarse scan can be used to abort a scheduled fine scan during the current touch sensing frame when no touch event is detected.