Optical Touch Screen Using Dual Imagers for Brightness and Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch screens, particularly those with signature capture capabilities, face issues of durability, reduced screen brightness, and high power consumption, especially with flexible membrane and IR sensor technologies, which are not adaptable to various screen sizes effectively.
Innovation Solution
An optical touch screen arrangement using dual linear optical imagers or cameras with charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) arrays, positioned above the display screen, intersecting their fields of view to detect touches without flexible membranes, maintaining screen brightness and minimizing power consumption, and easily adaptable to different screen sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flexible membrane technology is used for touch screens, then the screen can detect touches, but the membrane wears out and becomes damaged in demanding commercial applications
Solution Approach 1:
The patent replaces the mechanical flexible membrane system with an optical imaging system using CCD or CMOS cameras. Instead of relying on a physical membrane that can wear out, the system uses digital imaging sensors to detect touch points, eliminating the mechanical component that causes reliability issues in commercial applications.
Solution Approach 2:
The patent creates an optical copy or image of the touch screen surface using cameras positioned to capture the display area. This optical copying approach allows touch detection without direct physical contact with a membrane, as the camera captures light reflected from or transmitted through the display surface where touches occur.
2Ease of operation
If flexible membranes are positioned over the display, then touch detection is enabled, but screen brightness and contrast are reduced
Solution Approach 1:
The patent eliminates the flexible membrane layer entirely by substituting it with an optical imaging system. The cameras are positioned to capture the display surface directly without requiring a membrane overlay, thereby maintaining the display's optical properties and brightness while enabling touch detection through image processing.
3Adaptability or versatility
If dense arrays of IR LEDs and sensors are used for signature capture, then signature capture capability is achieved, but power consumption becomes too high and custom arrays must be created for each screen size
Solution Approach 1:
The patent uses standard, off-the-shelf CCD or CMOS camera modules that can be adapted to different screen sizes through simple positioning and field-of-view adjustment. This universal approach eliminates the need for custom-designed sensor arrays for each application, reducing development costs and allowing the same hardware platform to serve multiple screen sizes without requiring custom power-intensive IR LED arrays.
Solution Approach 2:
The patent replaces the power-intensive IR LED array system with a passive optical imaging system using standard cameras. Instead of actively illuminating the entire screen with IR LEDs, the system uses the camera's sensor array to detect light in the visible or near-infrared spectrum, dramatically reducing power consumption while maintaining signature capture capability.
4Measurement precision
If IR sensor technology with dense sensor arrays is used, then touch detection works well for location sensing, but the system becomes too expensive and power-intensive for some applications
Solution Approach 1:
The patent substitutes the power-intensive active IR sensing system with a passive optical imaging system using standard cameras. The cameras capture images of the touch area, and image processing algorithms determine touch location with high precision. This approach achieves comparable or superior location resolution with significantly lower power consumption, as the cameras only need to be activated when touch events are detected, rather than continuously illuminating and sensing the entire screen.
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 solution provides a durable, high-resolution touch screen with minimal power consumption and no reduction in screen brightness, enabling effective signature capture across various screen sizes without the need for delicate membranes or extensive power usage.
Implementation Method 1
Each imager has a row of light sensors, for example, a charge coupled device (CCD) array or a complementary metal oxide semiconductor (CMOS) array, for detecting light over a generally planar field of view
Data Source
AI summary
An optical touch screen arrangement includes two optical cameras arranged so that their planar fields of view intersect each other in a touch area situated adjacent a display screen operative for displaying visual prompts to solicit action from a user. The user's finger, or a pen, entering the touch area is detected, as is the user's signature.