Optical Overlay Filter for IR Touch Screen Interference
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Solution Overview
Problem
Touch screen systems in environments exposed to sunlight, such as aircraft cockpits, face interference from external infrared radiation, causing receivers to receive continuous signals even when the user touches the screen, leading to intermittent or incorrect touch detection due to the low output power of transmitters to conserve energy.
Innovation Solution
An optical overlay with a plano-convex lens and parallel ridges forming an optical filter is positioned around the perimeter of the electronic display system, filtering non-planar radiation and reducing external infrared interference by reflecting stray radiation away from the receivers using a dark coating and sawtooth geometry filter ridges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the transmitter output power is reduced to conserve energy, then energy consumption is reduced, but the receiver continues to receive external infrared radiation causing incorrect touch detection
Solution Approach 1:
The patent introduces an optical overlay with filter ridges as an intermediary component between the transmitter and receiver. This overlay selectively blocks external infrared radiation from reaching the receiver while allowing the transmitted infrared signals to pass through, thereby protecting the receiver without requiring increased transmitter power
Solution Approach 2:
The patent converts the harmful effect of external infrared radiation into a beneficial filtering mechanism. By using the ridges to reflect and block stray infrared radiation, the system turns the problematic external radiation into a filtered signal that no longer interferes with touch detection, allowing low-power operation while maintaining reliability
2Reliability
If the transmitter output power is increased to overcome external interference, then touch detection accuracy is improved, but energy consumption increases
Solution Approach 1:
The optical overlay acts as a protective intermediary that filters out external infrared radiation before it reaches the receiver. This allows the system to maintain accurate touch detection with low transmitter power, as the overlay prevents external interference rather than relying on high-power signals to overcome it
Solution Approach 2:
The patent extracts and removes the harmful external infrared radiation component from the signal path using the filter overlay. By taking out the interfering radiation before it reaches the receiver, the system maintains reliability without needing to increase transmitter power to compensate for interference
3Object-affected harmful factors
If the optical overlay includes filter ridges to block external radiation, then external infrared interference is reduced, but the device complexity increases
Solution Approach 1:
The patent implements the filter functionality using a thin optical overlay with ridges formed on its surface. This thin-film approach provides effective radiation filtering while maintaining a compact, lightweight structure that integrates easily with the display system, minimizing the increase in device complexity
Solution Approach 2:
The ridges on the optical overlay are formed with specific curved geometries that optimize their ability to reflect and block stray infrared radiation. The curved surfaces of the ridges enhance the filtering effect while maintaining a relatively simple overall structure that can be manufactured using standard molding techniques
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 optical overlay effectively filters out external infrared radiation, ensuring accurate touch detection by maintaining the integrity of the IR signal path and reducing interference from sources like sunlight, thereby enhancing the reliability of touch screen systems in sunlight-exposed environments.
Implementation Method 1
The combination of the planar surface of the inner wall and the convex surface of the outer wall may form a plano-convex lens
Implementation Method 2
filtering non-planar radiation and reducing external infrared interference by reflecting stray radiation away from the receivers
Implementation Method 3
The combination of the first plurality of ridges and the second plurality of ridges may form an optical filter
Data Source
AI summary
An optical overlay filters radiation striking the overlays at a non-planar incidence angle while passing and focusing in-plane signals. In embodiments, an optical overlay comprises an inner wall, an outer wall, an upper wall, and a lower wall. The inner wall may be formed to include a planar surface. The outer wall may be spaced apart from the inner wall and may be formed to include a convex surface. The combination of the planar surface of the inner wall and the convex surface of the outer wall may form a plano-convex lens. The upper wall may include a first plurality of ridges that are generally parallel to the inner wall. The lower wall may include a second plurality of ridges that are generally parallel to the inner wall. The combination of the first plurality of ridges and the second plurality of ridges may form an optical filter.