Optical Proximity Sensing With Opposed 1D Arrays for Touch Screens
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Solution Overview
Problem
Existing light-based touch screens require numerous light emitters and detectors along all four edges of the screen, making it difficult to integrate them into existing electronic devices without significant layout changes and increasing the bill-of-materials cost.
Innovation Solution
A one-dimensional array of alternating light emitters and detectors is used along opposite edges of the screen, with triangulation to determine object location, reducing the number of components required and enabling integration in a limited area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light emitters and detectors are placed along all four edges of the screen, then two-dimensional touch detection capability is achieved, but the number of components increases and integration difficulty increases
Solution Approach 1:
The patent divides the touch detection function into two separate one-dimensional arrays: one array of light emitters and another array of light detectors. This segmentation allows the system to achieve two-dimensional touch detection capability while using fewer total components compared to placing detectors along all four edges. The emitter array projects light beams across the screen, and the detector array receives reflected light, enabling coordinate determination through triangulation.
Solution Approach 2:
The patent transitions from a two-dimensional arrangement of components (detectors along all four edges) to a one-dimensional arrangement (separate emitter and detector arrays along opposite edges). This dimensional reduction maintains the capability for two-dimensional touch detection while significantly reducing component count and simplifying integration into existing devices.
2Reliability
If numerous light emitters and detectors are used along all four edges, then complete coverage for touch detection is achieved, but bill-of-materials costs increase
Solution Approach 1:
By segmenting the touch detection system into separate emitter and detector arrays positioned along opposite edges, the patent reduces the total quantity of optical components required. This segmentation maintains comprehensive touch detection coverage across the screen while minimizing component count, thereby reducing bill-of-materials costs.
Solution Approach 2:
The light beams projected by the emitter array serve multiple functions: they illuminate the screen for display purposes and simultaneously serve as the detection medium for touch sensing. This multi-functionality eliminates the need for separate illumination systems, reducing overall component quantity and cost.
3Measurement precision
If light emitters and detectors are placed along all four edges, then accurate touch location detection is achieved, but integration into existing devices becomes difficult
Solution Approach 1:
The patent simplifies integration by reducing the component arrangement from two-dimensional (along all four edges) to one-dimensional (along opposite edges only). This dimensional change allows the sensor arrays to be integrated into existing device layouts more easily while maintaining accurate touch location detection through the triangulation method.
Solution Approach 2:
The patent introduces light beams as an intermediary medium that connects the emitter array and detector array. These light beams traverse the screen area, enabling touch detection without requiring direct placement of components along all edges. This intermediary approach facilitates easier integration into existing device structures.
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 configuration allows for efficient two-dimensional touch detection with reduced components, facilitating integration into existing devices and lowering costs.
Implementation Method 1
The light detectors detect light from the emitters that has been reflected by an object inserted into the light beam path
Implementation Method 2
The distance between an emitter and a detector that detects light reflected from the emitter's beam, together with the fixed angle, is used to determine the location of the reflecting object by triangulation
Data Source
AI summary
An optical method for identifying locations of objects in a plane, including serially projecting light beams along a detection area, from a plurality of locations along an edge of the detection area, whereby a reflective object inserted into the detection area reflects the projected light beams, directing the reflections of the projected light beams arriving at the edge of the detection area onto a plurality of light detectors, in a manner that maximizes amounts of reflected light arriving at the detectors when the light arrives at a particular angle in relation to the edge, and calculating two-dimensional coordinates of the inserted object in the detection area based on the particular angle and the outputs of the detectors.