Optical Touch System Dynamic Light Intensity Calibration
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Solution Overview
Problem
Optical touch systems face challenges in accurately detecting touch positions due to overexposure or underexposure issues when using reflective frames, as high-intensity light from the light emitting unit can cause errors in detecting objects close to the light source, while reducing light intensity leads to poor detection of objects farther away from the light emitting unit.
Innovation Solution
The system employs a reflecting unit, light emitting modules, and an image detecting module to alternately provide first and second detecting lights with different intensities, allowing the processing unit to determine the object's position by analyzing signals generated when the object obstructs portions of these lights, thereby calibrating light intensity to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the illumination intensity of the light emitting unit is maintained at sufficient intensity to cover the whole display panel, then the detection range is improved, but the light detector becomes overexposed to reflected light from objects close to the light source, causing detection errors
Solution Approach 1:
The patent applies dynamics by making the light intensity adjustable rather than fixed. The control unit dynamically adjusts the light emitting unit's intensity based on the detected position of the touch object. When the object is close to the light source, the intensity is reduced to prevent overexposure; when the object is far from the light source, the intensity is increased to ensure sufficient illumination for detection.
Solution Approach 2:
The patent changes the physical parameter of light intensity based on the spatial relationship between the light source and the touch object. The control unit modifies the illumination parameter dynamically, reducing intensity for close objects and maintaining or increasing intensity for distant objects, thereby resolving the contradiction between detection range and detection accuracy.
2Measurement precision
If the light intensity of the light emitting unit is reduced to avoid detecting high intensity reflected light, then overexposure is prevented, but objects on the region of the display panel away from the light emitting unit can be hardly detected
Solution Approach 1:
The system dynamically adjusts light intensity based on real-time detection of object position. When an object is detected far from the light source, the control unit increases the light emitting unit's intensity to ensure sufficient illumination reaches the distant object, thereby maintaining detection capability across the entire display panel while avoiding overexposure of close objects.
Solution Approach 2:
The illumination parameter is changed adaptively according to the distance between the light source and the touch object. For distant objects, the system increases light intensity to extend effective detection range; for close objects, it reduces intensity to prevent overexposure, thus resolving the trade-off between detection range and accuracy.
3Device complexity
If a single light intensity is used for the light emitting unit, then the device complexity is reduced, but the detection precision varies for objects at different distances from the light source
Solution Approach 1:
The system performs preliminary detection to determine the position of the touch object before adjusting the light intensity. The control unit first detects where the object is located on the display panel, then proactively adjusts the light emitting unit's intensity to the appropriate level for that specific position, ensuring optimal detection precision without requiring complex hardware.
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 effectively avoids detection errors by using higher intensity light for distant objects and lower intensity light for close objects, enhancing the precision of touch detection and reducing manufacturing costs without compromising accuracy.
Implementation Method 1
The light emitting module is disposed beside the base plane and provides a first detecting light and a second detecting light with different intensities by turns, where the first detecting light and the second detecting light are transmitted to the reflecting unit through a front of the base plane
Implementation Method 2
The reflecting unit reflects the first detecting light and the second detecting light and causes the first detecting light and the second detecting light to be transmitted to the image detecting module through the front of the base plane
Implementation Method 3
When the object approaches or touches the base plane, at least a portion of the first detecting light and at least a portion of the second detecting light are obstructed by the object
Data Source
AI summary
An optical touch system including a reflecting unit, at least one light emitting module, at least one image detecting module, and a processing unit is provided. The reflecting unit, the light emitting module, and the image detecting module are disposed beside a base plane. The light emitting module provides a first detecting light and a second detecting light with different intensities by turns. The first detecting light and the second detecting light are transmitted to the reflecting unit. The image detecting module generates a first signal and a second signal. When an object approaches or touches the base plane, at least a portion of the first detecting light and a portion of the second detecting light are obstructed by the object. The processing unit determines a position of the object. Additionally, a method of touch detection, a method of calibration, and a computer program product are also provided.