SAW Touch Panel Signal Segmentation for Position Detection
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Solution Overview
Problem
Large-size surface acoustic wave (SAW) touch panels face challenges in accurately detecting touch positions due to signal attenuation over long propagation distances, leading to weak signals that are difficult to distinguish from noise.
Innovation Solution
The implementation of multiple SAW segments propagated on the touch panel, with partial output electrical signals generated based on different portions of each SAW segment and amplified to varying degrees, forming a complete output electrical signal to enhance signal strength and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of the SAW touch panel is increased, then the area of the touch panel is improved, but the signal attenuation increases and the detection precision deteriorates
Solution Approach 1:
The patent divides the propagation path of SAW segments into multiple sections along the propagation direction. Each section corresponds to a specific reflection unit group, allowing the system to process and amplify signals from different segments independently. This segmentation enables the panel to maintain detection precision across large areas by treating distant segments with appropriate gain adjustments.
Solution Approach 2:
The patent applies different gain values to different segments of the SAW propagation path. Reflection units closer to the transmitting unit use lower gain, while those farther away use higher gain to compensate for signal attenuation. This local quality adjustment ensures that signals from all areas of the large panel are amplified to comparable levels, maintaining detection precision throughout the entire panel area.
2Area of stationary object
If the propagation distance of SAW signals is increased, then the area of the touch panel is improved, but the signal strength deteriorates
Solution Approach 1:
The patent dynamically adjusts the gain parameter for different reflection units based on their distance from the transmitting unit. By changing the gain parameter according to propagation distance, the system compensates for signal attenuation and maintains adequate signal strength across the entire large panel area, enabling effective touch detection even at the farthest points.
3Area of stationary object
If the number of reflection units is increased, then the area of the touch panel is improved, but the signal attenuation increases
Solution Approach 1:
The patent organizes reflection units into multiple groups or segments along the propagation path. Each segment is associated with a specific gain value, allowing the system to manage signal attenuation in a structured manner. This segmentation approach enables the panel to accommodate more reflection units across larger areas while maintaining signal integrity through targeted amplification of each segment.
Solution Approach 2:
The patent applies differentiated gain values to different groups of reflection units based on their positional characteristics. Reflection unit groups farther from the transmitting unit receive higher gain to compensate for the cumulative attenuation from multiple reflections. This local quality adjustment ensures that energy loss is compensated proportionally across the entire panel, enabling the use of numerous reflection units without excessive signal degradation.
4Power
If the gain is increased to compensate for signal attenuation, then the signal strength is improved, but the hardware gain performance limitations are reached
Solution Approach 1:
The patent divides the gain compensation into multiple discrete levels, one for each segment or group of reflection units. Instead of requiring a single high-gain amplifier that would push hardware limits, the system applies multiple moderate gain stages corresponding to different segments. This segmented approach achieves the necessary overall signal strength while keeping individual amplifier stages within their optimal performance ranges.
Solution Approach 2:
The patent adjusts the gain parameter in a distributed manner across multiple reflection unit groups rather than concentrating all gain requirements in a single stage. By changing and optimizing the gain parameter for each segment independently, the system achieves the necessary total amplification while maintaining each hardware stage within its linear operating region, avoiding distortion and performance degradation associated with excessive single-stage gain.
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
This approach significantly increases the size of the SAW touch panel that can be effectively used while maintaining signal quality, allowing for accurate detection of touch positions by amplifying the received SAW signals and maintaining them within a predefined range, thus overcoming the limitations of hardware gain performance.
Implementation Method 1
It converts an electrical signal to the SAW signal by using a transducer including a piezoelectric material
Implementation Method 2
These reflectors r are all partially transmissive and partially reflective
Data Source
AI summary
The present invention provides a method and device for position detection. For detection of a touch position, a segment of surface acoustic wave (SAW) is provided multiple times to be propagated on a SAW touch panel, and the multiple SAW segments are received by the SAW touch panel. In addition, during or after reception, partial output electrical signals are provided based on different portions of each received SAW segment to construct a complete output electrical signal.