Optical Scanning Device Stray Light Noise Reduction
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Solution Overview
Problem
Conventional optical scanning devices for image display apparatuses suffer from image noise due to diffusely reflected stray light, which is particularly noticeable in varying light environments like automobiles, especially at night.
Innovation Solution
An optical scanning device that includes multiple light sources with specific wavelengths (600 nm or more) and a light deflector system, where the light receivers detect the light at predetermined timings to adjust the scanning position and reduce stray light interference by using red light with a wavelength of 650 nm as the signal light, minimizing image noise in both bright and dark conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light sources with wavelength less than 600 nm are used for optical scanning, then the scanning light can be effectively detected by the light receiver, but diffusely reflected stray light mixes with the scanning light causing image noise
Solution Approach 1:
The patent changes the wavelength parameter of the light source from conventional visible light (less than 600 nm) to near-infrared light (600 nm or more). This parameter change allows the scanning light to be distinguished from stray light based on wavelength, enabling the light receiver to detect only the scanning light while ignoring diffusely reflected stray light, thus eliminating image noise.
2Reliability
If the light receiver continuously monitors all light in the apparatus, then all light sources can be detected, but stray light is mixed with scanning light reducing image quality
Solution Approach 1:
The patent applies local quality by making the light receiver selectively responsive to specific wavelength ranges. The light receiver is configured to detect only near-infrared light (600 nm or more) while being insensitive to other wavelengths, creating a localized detection capability that distinguishes scanning light from stray light based on their spectral characteristics.
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 effectively reduces image noise caused by stray light in both bright and dark environments by using light with a wavelength of 600 nm or more, specifically 650 nm, as the signal light, enhancing image quality and visibility in automotive head-up displays.
Implementation Method 1
a light deflector scans light emitted from a plurality of light sources on a surface to be scanned
Implementation Method 2
a light receiver receives light emitted from at least one of the light sources
Data Source
AI summary
An optical scanning device includes a plurality of light sources, a light deflector, a light receiver, and circuitry. The light deflector scans light emitted from the plurality of light sources on a surface to be scanned. The light receiver receives light emitted from at least one of the light sources, at a predetermined timing. The circuitry adjusts a scanning position of the light deflector based on a timing at which the light receiver receives the light. The circuitry turns on at least one of the plurality of light sources that emits light having a wavelength of 600 [nm] or and causes the light receiver to receive the light at the predetermined timing.