Optical Touch Apparatus Ghost Point Elimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical touch technology faces challenges in accurately identifying multiple touch points due to the generation of ghost points, which increases complexity and calculation time, especially with increasing numbers of touching objects, and current solutions involve adding more sensors, thereby increasing costs.
Innovation Solution
The optical touch apparatus and method employ a light source module and two optical sensing modules positioned at the corners of the touch area, operating in different touch modes to control the light source and sense signals, allowing for the determination of touch features and positions without increasing the number of sensors, thereby reducing ghost point occurrences and calculation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If more sensors are added to determine ghost points and filter real touch points, then multi-touch accuracy is improved, but product cost increases
Solution Approach 1:
The light source module alternates between emitting light and not emitting light in different touch modes. In the first touch mode, the light source emits light for sensing; in the second touch mode, the light source does not emit light for sensing. This periodic action allows the system to capture different sensing signals that can be used to identify and eliminate ghost points, achieving accurate multi-touch detection without adding more sensors.
Solution Approach 2:
The system changes the working state parameter of the light source module between different touch modes. By controlling the light source to emit or not emit light, the system creates different optical conditions that result in distinguishable sensing signals. This parameter change enables the processing unit to differentiate between real touch points and ghost points through signal analysis, maintaining measurement precision without increasing sensor quantity.
2Measurement precision
If more sensors are added to determine ghost points and filter real touch points, then multi-touch accuracy is improved, but calculation time increases
Solution Approach 1:
The system uses periodic light emission and non-emission cycles to generate distinguishable sensing signals. By capturing signals during different light states, the processing unit can efficiently identify ghost points through pattern recognition rather than complex calculations involving multiple simultaneous sensor readings, thereby reducing calculation time while maintaining accuracy.
Solution Approach 2:
The system extracts ghost point information from the sensing signals by analyzing the differences between signals obtained in different touch modes. Instead of processing all sensor data simultaneously, the system extracts and compares specific signal characteristics that indicate ghost points, simplifying the calculation process and reducing computation time while maintaining high identification accuracy.
3Adaptability or versatility
If the quantity of touching objects increases, then multi-touch capability is improved, but complexity of identifying and calculating touch positions increases
Solution Approach 1:
The periodic light emission pattern creates distinct signal signatures for each touch event. When multiple touching objects are present, the system captures sensing signals during different light states, and the processing unit can separate and identify each touch point by analyzing the temporal and spatial patterns of the signals, reducing the complexity of multi-touch identification.
Solution Approach 2:
The light source module acts as an intermediary that modulates the sensing signals based on touch events. By controlling the light source to emit or not emit light, the system creates intermediate signal states that help the processing unit distinguish between real touch points and ghost points, even when multiple touching objects are present, thereby simplifying the overall processing complexity.
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 enables accurate multi-touch functionality with reduced product costs and calculation time by effectively distinguishing real touch points from ghost points, enhancing the efficiency of optical touch systems.
Implementation Method 1
A determination is made according a touching feature generated by the optical sensing module according to a part of light from the touch light source being reflected or blocked by a touching object
Data Source
AI summary
An optical touch apparatus including a light source module, two optical sensing modules and a processing unit is provided. The light source module provides a touch light source for a touch area. The optical sensing modules are disposed corresponding to two corners of the touch area. The processing unit is coupled to the light source module and the optical sensing modules, and controls the light source module to provide the touch light source in a first touch mode and a second touch mode and stop providing the touch light source in a third touch mode. Each of the optical sensing modules continuously senses and outputs a plurality of sensing signals. The processing unit determines a plurality of touching features of the sensing signals respectively to calculate positions of a plurality of touching objects on the touch area. An optical touch method is also provided.