Infrared Distance Sensing with Refracted Wide-Angle BPF Reception
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Solution Overview
Problem
Existing distance measurement devices for autonomous driving face a trade-off between maintaining a high signal-to-noise ratio (S/N ratio) and receiving light from a wide angle range, as band-pass filters often shield obliquely incident light, reducing the effective measurement angle.
Innovation Solution
Incorporating a band-pass filter member with a refraction member, such as a microlens array or prism sheet, to refract obliquely incident light onto the band-pass filter, allowing wide-angle measurement while maintaining a high S/N ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a band-pass filter is used to improve the S/N ratio by blocking light in wavelength ranges other than the measurement light, then the S/N ratio is improved, but the angle range of light that can be received by the light-receiving element is narrowed due to short-wavelength shift when light is incident in an oblique direction
Solution Approach 1:
A refraction member is introduced as an intermediary component between the band-pass filter and the light-receiving element. This refraction member refracts obliquely incident measurement light so that it becomes substantially perpendicular to the band-pass filter, allowing the filter to transmit the light effectively while still receiving light from a wide angle range.
Solution Approach 2:
The solution addresses the angular limitation by adding a spatial transformation function through the refraction member. This changes the dimensional relationship between incident light angles and filter transmission characteristics, allowing oblique light to be redirected into the perpendicular transmission range of the band-pass filter.
2Adaptability or versatility
If the wavelength range of the band-pass filter is widened to allow obliquely incident measurement light to pass through, then the angle range of light reception is improved, but light with wavelengths other than the measurement light wavelength can also transmit through the filter, resulting in a decrease in the S/N ratio
Solution Approach 1:
The refraction member acts as a mediator that separates the functions of angle acceptance and wavelength filtering. It handles the angular component by refracting oblique light into the perpendicular range, while the band-pass filter maintains its narrow wavelength selection capability, thus preserving the S/N ratio while expanding the angle range.
3Adaptability or versatility
If a large number of distance measurement devices are mounted on one automobile to measure distance to objects in all directions, then the angle range of measurement is improved, but the device complexity and cost increase
Solution Approach 1:
The modified distance measurement device achieves multi-directional light reception capability within a single device. The refraction member enables the light-receiving element to effectively receive measurement light from a wide angle range, making one device capable of performing the function that previously required multiple devices.
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 device can measure infrared rays reflected by objects over a wide angle range with a high S/N ratio, enabling effective distance measurement for autonomous driving applications.
Implementation Method 1
a refraction member that refracts the infrared ray incident onto the band-pass filter in a direction substantially perpendicular to the band-pass filter
Data Source
AI summary
An object is to provide a distance measurement device capable of receiving measurement light reflected by an object by responding to a wide angle range with a high S/N ratio. The object is achieved by the distance measurement device including: an infrared light source; a light receiving section that receives an infrared ray emitted from the light source and reflected by an object; and a band-pass filter (BPF) member that is disposed on a light-receiving surface side of the light receiving section and through which the infrared ray is transmitted, in which the BPF member includes a BPF and a refraction member that is disposed in contact with the BPF and refracts the infrared ray.