Touch Screen Routing Trace Configuration for Border Reduction
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Solution Overview
Problem
Conventional touch screen display devices face challenges in reducing border dimensions while maintaining accurate touch event detection due to limited board space for routing traces, as the current routing configurations consume significant space and lead to differences in routing trace path lengths, affecting signal uniformity and detection accuracy.
Innovation Solution
A touch sensitive input device with a routing trace configuration that combines single and double routing methods on the same touch panel, where transmit lines are coupled to routing traces on one side, both sides, and receive lines are coupled to a third side, allowing for reduced trace widths and compensating for path length differences through offset adjustments in digital sense signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional routing configurations are used to connect transmit lines to routing traces on both sides of the touch panel, then the routing trace path lengths can be balanced, but the border width consumes significant space
Solution Approach 1:
The transmit lines are divided into three subsets: first subset coupled to routing traces on only the first side, second subset coupled to routing traces on only the second side, and third subset coupled to routing traces on both sides. This segmentation allows different routing strategies for different groups of lines, reducing overall border width while managing path length variations.
Solution Approach 2:
Offset values are applied to digital sense signals based on their corresponding transmit line subset to compensate for path length differences. This parameter adjustment maintains detection accuracy despite the reduced and asymmetric routing configuration.
2Area of stationary object
If routing traces are reduced in width to save board space, then the border dimensions can be reduced, but the path length differences affect signal uniformity
Solution Approach 1:
Different offset compensation strategies are applied to different subsets of digital sense signals based on their routing characteristics. Signals from the first subset receive one offset value, signals from the second subset receive another offset value, and signals from the third subset receive a different offset value, customizing the compensation to local routing conditions.
Solution Approach 2:
Offset values are determined and applied in advance to the digital sense signals before further processing. This preliminary compensation corrects for the anticipated path length differences caused by the reduced routing configuration, ensuring signal uniformity is maintained throughout subsequent operations.
3Length of stationary object
If single routing method is used to reduce trace width, then border dimensions are reduced, but path length differences cause detection inaccuracies
Solution Approach 1:
Offset values are applied to compensate for the path length differences introduced by the single routing method. The offset values are specifically calculated for each subset of transmit lines to account for their unique routing path lengths, maintaining detection accuracy despite the reduced trace width.
Data Source
AI summary
Touch sensitive input devices and routing trace configurations designed to reduce border dimensions of such devices are provided herein. The touch sensitive input devices include a touch panel having a plurality of transmit lines and a plurality of receive lines, which are arranged with the plurality of transmit lines in a grid pattern, such that a sense node is disposed on the touch panel at each intersection of the transmit and receive lines. More specifically, the touch panel includes a first subset of the transmit lines coupled to routing traces on only a first side of the touch panel, a second subset of the transmit lines coupled to routing traces on only a second side of the touch panel, and a third subset of the transmit lines coupled to routing traces on both the first side and the second side of the touch panel. Methods are provided herein for compensating for differences in routing trace path lengths, so as to provide accurate detection of touch event locations on the touch panel.