Position Detecting Device Polarization Filter Glossy Surface
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Solution Overview
Problem
Position detecting devices and projectors struggle with erroneous recognition of touch positions on glossy surfaces due to high reflection intensity, leading to incorrect touch position detection.
Innovation Solution
A position detecting device equipped with a light emission unit emitting light in a predetermined wavelength band, a polarization filter that transmits p-polarized light and blocks s-polarized light, and an imaging unit that images the surface obliquely through the polarization filter, along with a projector that projects light in a different wavelength band and associates the projected light position with the detected object position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera is used to detect touch position on a glossy surface, then touch position detection is enabled, but erroneous recognition occurs due to high reflection intensity
Solution Approach 1:
The patent introduces a polarization filter as an intermediary component between the imaging unit and the glossy surface. This filter selectively transmits p-polarized light (valid reflection from touch point) while blocking s-polarized light (invalid reflection from glossy surface), thereby mediating the interaction between the imaging system and the reflective surface to eliminate erroneous detections
Solution Approach 2:
The patent changes the polarization state parameter of the reflected light by using a polarization filter. By filtering based on polarization direction (p-polarized vs s-polarized), the system transforms the light field parameters to distinguish valid touch signals from invalid reflections, resolving the contradiction between enabling detection and ensuring reliability
2Ease of operation
If light reflection from glossy surface is utilized for touch detection, then touch input functionality is achieved, but wrong optical paths enter the camera causing erroneous recognition
Solution Approach 1:
The patent converts the harmful effect of high reflection intensity on glossy surfaces into a beneficial signal. By utilizing the polarization characteristics of reflected light, the system distinguishes between valid touch reflections (p-polarized) and invalid surface reflections (s-polarized), transforming the previously harmful glare into a useful detection mechanism
Solution Approach 2:
The polarization filter serves as an intermediary that selectively allows valid light paths (p-polarized) to pass through while blocking invalid light paths (s-polarized). This mediator component resolves the contradiction by enabling touch functionality while eliminating wrong optical path 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 configuration enhances the signal-to-noise ratio by distinguishing valid and invalid light paths, preventing erroneous touch position recognition and ensuring accurate detection on glossy surfaces.
Implementation Method 1
a polarization filter configured to transmit p polarized light of light reflected on the plane surface and to block s polarized light
Implementation Method 2
light reflected on the plane surface
Data Source
AI summary
Provided is a position detecting device including: a light emission unit configured to emit light in a predetermined wavelength band in a manner substantially parallel to a plane surface; a polarization filter configured to transmit p polarized light of light reflected on the plane surface and to block s polarized light thereof; and an imaging unit configured to perform imaging of the plane surface obliquely from above with the light in the predetermined wavelength band through the polarization filter.