Borderless Touchscreen Panel Routing Traces Beneath Electrodes
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Solution Overview
Problem
Conventional capacitive touchscreen panels have an inactive border region due to routing circuitry along the outer edges, reducing the size of the active touch-sensitive area and affecting usability and display capabilities.
Innovation Solution
A borderless touchscreen panel design where transmit and sensing electrodes are arranged to allow receiving traces to be routed beneath the electrodes, eliminating the need for an inactive border by integrating them within the active area, using a two-phase interlaced scanning method and reducing sensor pitch to compensate for potential accuracy issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If routing circuitry is disposed along the outer edges of the touchscreen panel, then the circuitry can be easily routed and connected, but it creates an inactive border that reduces the active touch-sensitive area
Solution Approach 1:
The patent moves the routing circuitry from a two-dimensional edge-based arrangement to a three-dimensional configuration by routing traces through the thickness of the panel layers. Receiving traces are routed beneath transmit electrodes in the Z-direction, allowing circuitry to pass through the active area without interfering with touch detection, thereby eliminating the inactive border while maintaining routing functionality
Solution Approach 2:
The patent nests the receiving traces within the space occupied by the transmit electrodes by routing the receiving traces beneath the transmit electrodes. This nested arrangement allows both sets of traces to coexist in the same planar footprint without interfering with each other, enabling the elimination of the border region while maintaining proper circuit routing
2Area of stationary object
If receiving traces are routed beneath transmit electrodes, then the inactive border is eliminated and active area increases, but trace coupling and signal integrity become more challenging
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the receiving traces and transmit electrodes. This dielectric layer electrically isolates the two trace types while allowing them to be in close proximity, preventing signal interference and maintaining signal integrity. The dielectric material acts as a mediator that enables the nested routing arrangement without compromising electrical performance
Solution Approach 2:
The patent extracts the routing function from the traditional edge-based location and embeds it within the active area by routing receiving traces beneath transmit electrodes. This extraction allows the circuitry to be relocated from the border region into the previously inactive border area, effectively expanding the active touch-sensitive area while maintaining proper signal routing through careful trace design
3Measurement precision
If the sensor pitch is reduced to compensate for blind spots, then the touch detection accuracy improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary compensation by designing the outermost transmit and sensing electrodes to extend beyond the traditional border region. This preliminary extension of electrodes into the former border area creates overlapping sensing zones that compensate for the blind spots that would otherwise exist at the panel edges, improving touch detection accuracy without requiring excessive reduction in sensor pitch
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Increases the active area of the touchscreen panel by eliminating the inactive border, maintaining touch detection and display functionality without obstructing the active region, and reducing the impact of blind spots through optimized sensor arrangement and pitch reduction.
Implementation Method 1
a first set of receiving traces routed beneath the first transmit electrode and extending in the first direction along a length of the first transmit electrode, the first set of receiving traces coupled to a first subset of the rows of series-connected sensing electrodes
Implementation Method 2
Touchscreen panels implement sensing circuitry to detect a user touch on the display panel
Data Source
AI summary
A borderless touchscreen panel includes a first conductive layer having rows of capacitive sensors and receiving traces, and a second conductive layer having columns of sensor bars and transmitting traces. The capacitive sensors are coupled to control circuitry via the receiving traces, and the sensor bars are coupled to the control circuitry via the transmitting traces. Peripheral sensor bars are disposed over the receiving traces such that the receiving traces can be routed within an active portion of the borderless touchscreen panel without obstructing its touch-detection capabilities. Furthermore, the receiving traces are comprised of a transparent material such as indium tin oxide, and therefore do not obstruct the display capabilities of the active portion. Thus, there is no need for an inactive border region since the receiving traces are disposed within the active portion without obstructing either the touch-detection or display capabilities of the borderless touchscreen panel.