Optical Touch Device Using Time Index Lookup Table
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Solution Overview
Problem
Conventional optical touch devices require complex triangulation computations to determine touch locations, which complicates the process of distinguishing actual touches from ghost touches.
Innovation Solution
An optical touch device with first and second light beam scanning modules, each with a rotating actuator and mirror, continuously scans a touch region with varying incident angles, generating time index signals used by a processing unit in conjunction with a look-up table to locate touches without complex triangulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If triangulation computation is used to determine touch locations, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent pre-calculates and stores correspondence relationships between incident angles and touch positions in a lookup table before operation. During actual touch detection, the system simply queries the pre-computed table using measured incident angles, avoiding real-time triangulation computations while maintaining high positioning accuracy
Solution Approach 2:
The patent replaces the complex mathematical triangulation computation system with a simplified lookup table query system. By substituting real-time computational processing with pre-computed data retrieval, the system achieves the same measurement precision with significantly reduced computational complexity
2Measurement precision
If triangulation computation is used to distinguish actual touches from ghost touches, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system pre-computes and stores the correspondence between incident angles, touch positions, and touch validity judgments (actual vs. ghost touches) in a lookup table. During operation, both position determination and touch validation are achieved through simple table queries, eliminating time-consuming real-time computations while maintaining high detection accuracy
3Measurement precision
If complex computation is used for touch location determination, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent performs all complex triangulation computations and stores their results in a lookup table during system initialization or calibration phase. During actual touch processing, the system achieves high-speed operation by querying pre-computed results, thereby maximizing processing speed without sacrificing measurement precision
Solution Approach 2:
The patent substitutes real-time complex computational processing with efficient lookup table queries. This replacement transforms the system from computation-intensive operation to data retrieval-intensive operation, significantly improving processing speed and productivity while maintaining the same level of measurement precision
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
Enables efficient and accurate location of touches within the touch region, simplifying the process by using time index signals and reducing computational complexity.
Implementation Method 1
The first mirror is positioned to reflect the first light beam to generate the first scanning light beam incident into the touch region
Implementation Method 2
The first rotating actuator is coupled to the first mirror for continuously rotating back and forth the first mirror about the first center to thereby vary the first incident angle of the first scanning light beam within the predetermined angle range during each scanning cycle
Implementation Method 3
The first light sensor module is mounted to the peripheral region for sensing at least one reflected first scanning light beam generated due to reflection of the first scanning light beam by at least one touch within the touch region so as to output a first sensing signal
Implementation Method 4
The processing unit is operable to locate the at least one touch based on a first candidate one of the time indexes, which is represented by the first time index signal that is received by the processing unit upon receipt of the first sensing signal by the processing unit
Data Source
AI summary
An optical touch device includes: two light beam scanning modules each scanning a touch region of a panel body with a scanning light beam, whose incident angle varies with time, and outputting a time index signal associated with the incident angle; two light sensor modules each sensing a corresponding reflected scanning light beam generated due to presence of a touch within the touch region so as to output a sensing signal; and a processing unit for locating the touch based on the time index signal from each light beam scanning module, the sensing signal from each light sensor module, and a look-up table having pieces of angle information corresponding to a series of time indexes and associated with the incident angle of each scanning light beam.