Optical Touch Input System Corner Sensor Reference Calibration
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Solution Overview
Problem
Infrared type touch input systems suffer from low touch resolution in upper areas due to dead zones caused by the angle formed by infrared sensors, leading to inaccurate touch detection and requiring larger system sizes, and are prone to errors from misalignment of optical sensor modules during manufacturing and assembly.
Innovation Solution
An optical touch input system is designed with optical sensor modules at multiple corners of a display panel, using retro-reflectors to emit and detect light, allowing for accurate touch detection by correlating impulse signals with reference angles, thereby eliminating dead zones and compensating for misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If infrared sensors are positioned at corners to cover the entire display panel, then the coverage area is improved, but dead zones are created in upper areas due to angle limitations, reducing touch resolution
Solution Approach 1:
The system divides the detection task into multiple segments by placing optical sensor modules at multiple corners (at least three corners) of the display panel. Each corner module detects a specific region, and the controller integrates information from all modules to achieve full-coverage detection without dead zones, resolving the contradiction between coverage area and measurement precision.
2Manufacturing precision
If optical sensor modules are manually aligned during assembly, then manufacturing precision is improved, but the complexity and time of the assembly process increase
Solution Approach 1:
The system implements self-alignment functionality where the controller automatically determines the positions of optical sensor modules by receiving direct light signals and establishing reference information. This eliminates the need for manual alignment during assembly, reducing assembly complexity while maintaining high positioning precision through automated calibration.
3Measurement precision
If optical sensor modules are positioned at multiple corners to eliminate dead zones, then touch detection accuracy is improved, but the system size and device complexity increase
Solution Approach 1:
Each optical sensor module serves multiple functions: it detects touch events in its local region, provides direct light signals for reference establishment, and contributes to overall system calibration. This multi-functionality reduces the need for separate calibration components, thereby managing system complexity while achieving high detection accuracy through multiple corner modules.
4Manufacturing precision
If reference information is established based on direct light signals from corner emitters, then positioning accuracy is improved, but the system requires additional emitters and detectors increasing device complexity
Solution Approach 1:
The system merges the functions of emitters and detectors into integrated optical sensor modules positioned at corners. Each module contains both emission and detection capabilities, allowing direct light signals to be used for reference establishment without requiring separate emitter and detector components. This integration reduces overall device complexity while maintaining high positioning accuracy.
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
The system achieves improved touch accuracy and reduced errors by establishing new references based on direct light signals from emitters at corners, enhancing the effective viewing angle and allowing for correct touch detection regardless of sensor module alignment.
Implementation Method 1
Retro-reflectors are configured to retro-reflect light emitted by the optical sensor modules
Implementation Method 2
emitting light by emitters located at respective first, second, and third corners of the display panel, and receiving direct light by a detector located at a fourth corner of the display panel
Data Source
AI summary
A method of establishing a reference in an optical touch input system and a corresponding display panel, includes emitting light by emitters located at respective first, second, and third corners of the display panel, and receiving direct light by a detector located at a fourth corner of the display panel, the detector at the fourth corner detecting respective first, second, and third impulse signals generated by the direct light of the emitters located at the respective first, second, and third corners, the respective first, second, and third impulse signals corresponding to pixel positions of the detectors located at the fourth corner and correlating the respective pixel positions of the respective first, second, and third impulse signals with respective predetermined first, second, and third reference angles of the display panel.