COF Driving Circuit Noise Avoidance Line for Touch Sensing
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Solution Overview
Problem
Display devices with built-in touchscreens face issues with touch sensing errors due to increased noise when a chip-on-film (COF) type touch driving circuit is integrated with a source driving circuit, leading to inaccuracies in detecting touch coordinates.
Innovation Solution
A COF type driving circuit with a noise avoidance line structure is implemented, where the noise avoidance line is located outward of the outermost touch channel line and not connected to the display panel, receiving a noise avoidance signal identical or in phase with the touch driving signal to reduce noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a COF type source driving circuit is integrated with a touch driving circuit, then the number of driving circuit components is reduced, but touch sensing errors occur due to noise
Solution Approach 1:
The patent segments the driving circuit into separate source driving circuit and touch driving circuit regions on the circuit film, with dedicated signal lines for each function. This spatial segmentation allows independent optimization of each circuit's performance while maintaining integration benefits.
Solution Approach 2:
The patent introduces an intermediary shielding structure between the source driving circuit signal lines and touch channel lines. This intermediary element acts as a noise barrier, preventing electromagnetic interference from the source circuit from affecting touch sensing operations.
2Area of stationary object
If touch channel lines are placed adjacent to data channel lines for compact layout, then area is reduced, but noise interference increases causing sensing errors
Solution Approach 1:
The patent places an intermediary shielding line or ground line between adjacent touch channel lines and data channel lines. This intermediary structure physically separates the two signal types while maintaining compact overall layout, blocking noise transmission between neighboring lines.
Solution Approach 2:
The patent applies different structural characteristics to different regions of the circuit film. Specifically, noise shielding structures are applied locally at critical interfaces between source and touch circuits, while other regions maintain standard compact routing to minimize overall area.
3Ease of manufacture
If outermost touch channel lines are used without additional shielding, then manufacturing is simplified, but noise avoidance is insufficient leading to sensing errors
Solution Approach 1:
The patent incorporates noise shielding structures for outermost touch channel lines during the initial circuit film fabrication process. By pre-configuring these protective structures before final assembly, the design maintains manufacturing simplicity while ensuring noise protection is built-in from the start.
Data Source
AI summary
A display device having a built-in touchscreen and a driving chip, a circuit film, and a chip-on-film (COF) type driving circuit included in the display device. The COF type driving circuit performs data driving and touch driving in a combined manner. A source driving circuit outputs image data voltages through data channels. At least one touch driving circuit outputs touch driving signals through touch channels. The source driving circuit and the at least one touch driving circuit are mounted on an integrated circuit film. Data channel lines electrically connected to the data channels and touch channel lines electrically connected to the touch channels are disposed on the integrated circuit film. The noise avoidance line disposed on the integrated circuit film is located outward of an at least one outermost touch channel line.