Touch Signal Multiplexer and Load Compensation Circuit for Display Substrates
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Solution Overview
Problem
Existing touch display devices face challenges in achieving full-screen border integration due to limited touch pad numbers and incomplete charging of touch electrodes, particularly in medium to large-size high-resolution screens, where the distance between bonding pads and ICs restricts the number of effective touch pads and leads to parasitic capacitance issues.
Innovation Solution
A display substrate design that incorporates a touch signal multiplexer and load compensation circuits, allowing touch signals to be loaded onto touch signal lines in a time division mode, with load compensation circuits addressing parasitic capacitance by loading compensation signals onto other lines, thereby reducing the number of touch pads required and ensuring complete charging of touch electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of touch pads is increased to support more touch signal lines, then the touch functionality is improved, but the non-display area and border width increase
Solution Approach 1:
Multiple touch signal lines are merged and multiplexed through a single touch pad using time-division multiplexing. The touch selection circuit switches between different touch signal lines based on control signals, allowing one touch pad to serve multiple lines sequentially. This reduces the total number of touch pads needed while maintaining full touch functionality across all signal lines.
Solution Approach 2:
Each touch pad is designed with multi-functionality through the touch selection circuit that can connect the same touch pad to different touch signal lines at different times. The touch pad serves multiple purposes by being dynamically reassigned to different signal lines, thereby reducing the overall quantity of touch pads required for the display.
2Manufacturing precision
If touch signal lines are densely arranged to improve resolution, then the display quality is improved, but parasitic capacitance between adjacent lines increases
Solution Approach 1:
The load compensation circuit performs preliminary compensation by pre-charging or discharging touch signal lines before and after the main touch signal transmission. This preliminary action counteracts the parasitic capacitance effects that would otherwise distort the touch signals, allowing for denser line arrangement without signal interference.
Solution Approach 2:
The load compensation circuit provides feedback compensation by monitoring the charge state of touch signal lines and adjusting the compensation signals accordingly. This feedback mechanism ensures that parasitic capacitance effects are continuously compensated for, enabling higher density touch signal line arrangements while maintaining signal integrity.
3Length of stationary object
If the distance between bonding pads and ICs is reduced to achieve full-screen integration, then the border width is reduced, but the number of effective touch pads is limited
Solution Approach 1:
The touch selection circuit merges multiple touch signal lines into a single touch pad connection, allowing the limited number of bonding pads to support more touch signal lines through time-division multiplexing. This merging approach enables full-screen integration with reduced border width while maintaining adequate touch pad coverage.
Solution Approach 2:
The patent transitions from a spatial one-to-one mapping between touch pads and signal lines to a temporal multiplexing approach. By adding the time dimension through sequential switching, the limited bonding pads can effectively serve multiple signal lines, overcoming the physical constraints of reduced border width.
4Measurement precision
If touch electrodes are completely charged to ensure accurate touch detection, then the detection precision is improved, but the charging time increases
Solution Approach 1:
The load compensation circuit performs preliminary charging or discharging of touch signal lines before the main touch detection phase. This preliminary action ensures that the electrodes are properly initialized and charged to the correct levels, improving detection precision while the time investment is minimized through efficient sequencing.
Solution Approach 2:
The touch selection circuit uses periodic switching to sequentially charge and discharge touch signal lines in a rhythmic pattern. This periodic action allows complete charging of all electrodes in a systematic manner, ensuring detection precision while managing total charging time through optimized periodic cycles.
Data Source
AI summary
The present disclosure provides a display substrate and a display device, including a display area and a non-display area on at least one side of the display area; and a plurality of touch signal lines in the display area as well as a plurality of groups of touch selection circuits, a plurality of groups of load compensation circuits and a plurality of touch pads in the non-display area. The load compensation circuits are connected with the touch selection circuits, one group of touch selection circuits is electrically connected with one touch pad and at least two touch signal lines, and one group of load compensation circuits and one group of touch selection circuits connected with each other are electrically connected with one same touch signal line, and are arranged side by side in a vertical direction of the touch signal line.