Touch Panel Noise Reduction via Scanning Stop and Reset
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Solution Overview
Problem
Existing liquid crystal display devices with touch panels face challenges in temporarily stopping and restarting scanning of signal lines without introducing noise, which affects touch detection accuracy and panel durability.
Innovation Solution
A display device with a touch panel that includes scanning signal lines, a drive pulse output circuit, a clock signal output circuit, and a touch panel control unit, which allows for temporary stopping and restarting of scanning by using a reset start signal generation circuit to manage the active potential and clock signals, reducing noise interference during touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scanning is temporarily stopped in the middle of scanning signal lines for touch detection, then touch detection accuracy is improved, but noise from potential variations may interfere with detection
Solution Approach 1:
The patent applies preliminary action by resetting the finally applied active potential to a non-active potential before restarting scanning. This reset operation prepares the system in advance to eliminate potential noise from residual potentials, ensuring clean touch detection measurements when scanning resumes.
Solution Approach 2:
The patent implements periodic action by alternating between scanning periods and stop periods for touch detection. During stop periods, scanning is temporarily halted to perform touch detection without interference from scanning signal variations. This periodic alternation between scanning and detection phases ensures both display functionality and accurate touch detection.
2Stability of the object's composition
If scanning signal lines are continuously scanned for display refresh, then display quality is maintained, but touch detection cannot be performed during scanning periods
Solution Approach 1:
The patent divides the operation into periodic scanning periods for display refresh and stop periods for touch detection. During scanning periods, active potential is applied to maintain display quality. During stop periods, scanning is halted to enable touch detection. This periodic alternation resolves the contradiction by allocating different time periods for different functions.
Solution Approach 2:
The patent performs preliminary reset of the active potential to non-active potential during stop periods before restarting scanning. This preliminary action ensures that when scanning resumes, there is no residual potential interference, maintaining display stability while enabling touch detection during stop periods.
3Device complexity
If reset and start signals are generated externally, then scanning control is simplified, but circuit scale increases and frame size expands
Solution Approach 1:
The patent merges the reset start signal generation circuit with the existing drive pulse output circuit by arranging both on the same TFT substrate. The reset start signal generation circuit shares the substrate and spatial resources with the drive pulse output circuit, integrating multiple functions into a unified structure. This merging reduces overall circuit scale and prevents frame size expansion while maintaining simplified control signal generation.
Solution Approach 2:
The TFT substrate serves multiple functions by hosting both the drive pulse output circuit and the reset start signal generation circuit. This multi-functional use of the substrate eliminates the need for separate external circuits, reducing overall device complexity and frame size while maintaining the capability to generate both scanning and reset/start signals.
Data Source
AI summary
A display device with a touch panel includes: a plurality of scanning signal lines, which are aligned in a rectangular display region and in parallel with a side of the rectangular display region, to which an active potential as a potential for making a pixel transistor conductive is applied; drive pulse output circuits which sequentially apply the active potential to the scanning signal lines in the display region; a clock signal output circuit which applies a first clock signal as a clock signal for the drive pulse output circuits to a first clock signal line and stops the application of the first clock signal to the first clock signal line for a stop period during which the sequential application of the active potential is stopped in the middle thereof; and a touch panel control unit which detects contact with a display surface during the stop period.