Interactive Projector Detection Light Irradiation for Position Accuracy
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Solution Overview
Problem
Existing interactive projectors face challenges in achieving sufficient contrast between the pointing element and the projected screen, making it difficult to accurately detect the position of the pointing element, especially when external light is present.
Innovation Solution
The interactive projector employs a detection light irradiation section that emits near-infrared light, ensuring high contrast between the pointing element and the projected screen, even when the pointing element is outside or inside the screen, by adjusting the position of the detection light irradiation section to maintain high contrast across the projected screen area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detection light is emitted to detect the pointing element position, then the position detection capability is improved, but the contrast between the pointing element and the projected screen becomes insufficient when the pointing element is outside the screen
Solution Approach 1:
The patent applies local quality by differentiating the contrast requirements for different spatial regions. Inside the projected screen area, high contrast is maintained for accurate detection. Outside the screen area, the contrast is intentionally reduced below the threshold to prevent false detection, while still allowing the imaging section to capture the pointing element position through other means.
Solution Approach 2:
The patent changes the contrast parameter dynamically based on the pointing element's position relative to the projected screen. When the pointing element is inside the screen, the contrast is maintained above the threshold for accurate detection. When outside the screen, the contrast is reduced below the threshold to avoid misidentification, thus adapting the detection parameter to the spatial context.
2Adaptability or versatility
If the detection light irradiation section is positioned to detect pointing elements outside the screen, then the detection range is expanded, but the contrast inside the projected screen area decreases
Solution Approach 1:
The patent implements local quality by creating different contrast zones: inside the projected screen where high contrast enables accurate detection, and outside the screen where reduced contrast prevents false positives. This spatial differentiation allows the system to expand detection range while maintaining detection accuracy within the valid interaction area.
Solution Approach 2:
The patent inverts the conventional approach by not uniformly maximizing contrast across the entire detection area. Instead, it intentionally reduces contrast outside the projected screen area while maintaining it inside, using the threshold as a boundary condition to define the valid interaction zone rather than treating the entire detection area uniformly.
3Measurement precision
If high contrast is maintained across the entire detection area, then the pointing element is easily distinguishable, but false detection occurs when the pointing element is outside the projected screen
Solution Approach 1:
The patent changes the contrast parameter based on the spatial relationship between the pointing element and the projected screen. By setting the contrast threshold as a dynamic criterion rather than a fixed value, the system achieves high detection accuracy inside the screen while preventing false detections outside the screen, thus improving both measurement precision and detection reliability.
Solution Approach 2:
The patent employs feedback by using the projected screen's position information to dynamically adjust the contrast threshold for detection. The system continuously monitors whether the detected pointing element position falls within the projected screen area and adjusts the contrast requirement accordingly, providing feedback-based validation that prevents false detections outside the valid area.
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 configuration allows for accurate detection of the pointing element's position on the projected screen, both with and without external light, enhancing the usability and reliability of the interactive projector system.
Implementation Method 1
The detection light irradiation section is adapted to emit detection light used for detection of the pointing element toward an area of the projected screen
Implementation Method 2
the pointing element is irradiated with detection light such as an infrared ray, and the detection light reflected by the pointing element is imaged by the camera
Data Source
AI summary
An interactive projector includes a projection section, a detection light irradiation section, an imaging section, and a position detection section adapted to detect a position of the pointing element with respect to the projected screen based on an image, which is taken by the imaging section and includes the pointing element. The detection light irradiation section is disposed so that (i) first contrast in an image taken in the state in which the tip of the pointing element has contact with one position outside the projected screen is lower than a threshold value set in advance, and (ii) second contrast in an image taken in the state in which the tip of the pointing element has contact with an arbitrary position in the projected screen is higher than a threshold value set in advance for distinguishing the pointing element from the projected screen.