Optical Touch-Screen Imager Using Corner-Positioned CMOS Sensors
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Solution Overview
Problem
Existing touch-screen technologies face challenges with durability, brightness, cost, power consumption, and scalability, particularly in optical touch-screen imagers that rely on dense infrared sensor and LED arrays or bulky cameras.
Innovation Solution
An optical touch-screen imager design featuring a pair of image sensors positioned at corners of a touch area, coupled with a radiation source, where the image sensors have adjustable angular fields of view and are integrated with CMOS or CCD technology, allowing for efficient detection of object positions using radiation blocking, and a compact, low-height design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flexible membrane technology is used for touch screens, then the touch screen can be implemented, but the membrane is not durable and reduces display brightness and contrast
Solution Approach 1:
The patent removes the flexible membrane layer from the touch screen structure, replacing it with an optical imager system that directly detects touch events through light blocking detection, thereby eliminating the durability and brightness reduction issues caused by the membrane
Solution Approach 2:
The patent replaces the mechanical flexible membrane structure with an optical detection system using image sensors and light sources, where touch events are detected through changes in light patterns rather than mechanical deformation of a membrane
2Measurement precision
If a dense array of photosensors and LEDs is used for adequate resolution, then touch detection accuracy is improved, but the system becomes too expensive and too power-hungry
Solution Approach 1:
The patent uses standard off-the-shelf image sensor arrays that are designed for general imaging applications, allowing these multi-functional components to serve both imaging and touch detection purposes, thereby reducing cost and power consumption compared to specialized dense sensor arrays
Solution Approach 2:
The patent uses conventional image sensor technology and processing algorithms originally designed for digital imaging, adapting them for touch detection purposes rather than requiring custom-built specialized sensors, which reduces both cost and power requirements
3Measurement precision
If a dense array of photosensors and LEDs is used for adequate resolution, then touch detection accuracy is improved, but the system becomes too expensive
Solution Approach 1:
The patent employs standard image sensor arrays and LED arrays that are mass-produced for consumer electronics, making them inexpensive and readily available, rather than requiring custom-manufactured specialized touch sensors
Solution Approach 2:
The patent combines the touch detection function with existing display technologies and standard imaging components, eliminating the need for separate specialized touch sensor layers and reducing overall system cost
4Device complexity
If cameras are used to replace IR photosensors, then the number of sensors is reduced, but the cameras are bulky, making the touch-screen large, thick and heavy
Solution Approach 1:
The patent positions image sensors at the corners of the display rather than distributing them across the entire surface, and uses localized light sources at the edges, thereby achieving touch detection functionality with minimal component mass and maintaining a thin, lightweight profile
Solution Approach 2:
The patent positions image sensors and light sources at the boundaries and corners of the display area, using the perimeter space efficiently to achieve touch detection without adding bulk to the central display region, maintaining a thin and lightweight design
5Measurement precision
If custom arrays of LEDs and sensors are created for each screen size, then adequate resolution is achieved, but the system is not scalable
Solution Approach 1:
The patent uses standard image sensor arrays and LED arrays that can be configured for different screen sizes and resolutions by adjusting the detection algorithms and light source positioning, eliminating the need for custom-manufactured sensor arrays for each application
Solution Approach 2:
The patent achieves adaptability to different screen sizes by changing software parameters such as the field of view angle, light source positioning coordinates, and touch detection threshold values, rather than requiring physical reconfiguration of hardware arrays
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 solution provides a cost-effective, power-efficient, and scalable touch-screen solution with improved durability and user-friendliness by accurately detecting object positions with reduced thickness and weight, addressing the limitations of previous technologies.
Implementation Method 1
An optical touch-screen imager includes a radiation source and a pair of image sensors positioned at corners of a touch area. The image sensors receive the radiation and detect blockages of the radiation by an object
Data Source
AI summary
Embodiments of an apparatus comprising a CMOS image sensor including a pixel array formed in a substrate and a light guide formed on the substrate to receive light traveling in a plane parallel to a plane of the pixel array and incident on the edge of the image sensor and to re-direct the incident light into at least one pixel of the pixel array. Embodiments of an optical touch-screen imager comprising a substantially planar touch area and a detector positioned adjacent to the touch area, the detector comprising a CMOS image sensor as described above.