Position Detection Apparatus Using Differential Imaging to Isolate Indication Signals
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Solution Overview
Problem
Existing position detection apparatuses face accuracy issues when detecting an indication position of an indicator due to uneven light distribution in the detection area, particularly when external light or indoor illumination affects the detection process.
Innovation Solution
A position detection apparatus that captures image data both with and without the detection light, using differential image data to isolate the indication position by subtracting background image data obtained when the light source is off from operation image data, thereby reducing the influence of external light and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detection area is illuminated with detection light to improve the visibility of the indicator, then the indication position can be detected, but external light and indoor illumination create reflected light that decreases detection accuracy
Solution Approach 1:
The light source portion emits detection light in a periodic manner (alternating between on and off states). The imaging portion captures images at specific phases of this periodic cycle - specifically capturing a background image when the light is off and an operation image when the light is on. This periodic action allows separation of the detection light signal from the reflected light of external light sources.
Solution Approach 2:
The system performs preliminary capture of background image data when the detection light is not emitted, before capturing the operation image data when the detection light is emitted. This preliminary action of capturing the background without detection light enables subsequent differential processing to remove the influence of reflected light from external sources.
2Measurement precision
If captured image data is used directly for position detection, then the detection process is simple, but uneven light distribution and background light reduce detection accuracy
Solution Approach 1:
The patent introduces background image data as an intermediary element that mediates between the raw captured image data and the final position detection result. By performing differential processing between the operation image data and the background image data, the system creates corrected image data that has the influence of uneven light distribution and reflected light removed, thereby improving detection accuracy without requiring complex calibration procedures.
3Reliability
If the light source continuously emits detection light to maintain consistent detection conditions, then the detection process is continuous, but reflected light from external sources continuously interferes with detection accuracy
Solution Approach 1:
Instead of continuous emission, the light source operates periodically with alternating on and off phases. This periodic operation maintains detection capability while creating temporal separation between the detection light signal and the continuously present reflected light from external sources. The imaging portion synchronizes its capture operations with these periodic phases to achieve reliable detection.
Solution Approach 2:
The system maintains continuous detection capability by rapidly alternating between capturing background images (when light is off) and operation images (when light is on). This continuous cyclic operation ensures that detection can proceed without interruption while the useful action of emitting detection light is maintained only during the necessary phases to avoid continuous interference.
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 allows for highly accurate detection of the indication position by isolating the indication signal from background noise, enhancing the reliability of the detection process even in the presence of external light or indoor illumination.
Implementation Method 1
the image of the reflected light in which the external light entering from a window or the indoor illumination light is reflected on an object in the detection area
Implementation Method 2
a light source portion that emits detection light to the detection area
Data Source
AI summary
A position detection apparatus includes: an imaging portion that captures an image of a detection area for detecting indication positions of indicators; and an indicator detecting portion that detects the indication positions of the indicators based on operation image data captured by the imaging portion when indication operations by the indicators are performed in the detection area and background image data captured by the imaging portion when the indication operations by the indicators are not performed.