Imaging Device Raindrop Detection Prism Light Path
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Solution Overview
Problem
Conventional imaging devices for vehicles suffer from reduced light reception in the lower portion of the image sensor due to the reflection polarization prism, leading to lower brightness and reduced accuracy in vehicle detection and post-processing tasks.
Innovation Solution
An imaging device configuration that includes a light emitter, an illumination light guiding member such as a reflection polarization prism, an imager, and an optical member like a wavelength filter, which allows illumination light to be directed to both the first and second light-receiving portions of the image sensor without interruption, ensuring consistent light reception and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a reflection polarization prism is mounted on the inner wall surface of the windshield to enable raindrop detection, then raindrop detection capability is improved, but light reception at the lower portion of the image sensor is reduced
Solution Approach 1:
The image sensor is divided into two distinct light-receiving portions: a first light-receiving portion for receiving light from the front area and a second light-receiving portion for receiving reflected illumination light to detect raindrops. This segmentation allows each portion to be optimized for its specific function, with the first portion maintaining full light reception capability for vehicle detection while the second portion is dedicated to raindrop detection through reflected light.
2Measurement precision
If the reflection polarization prism is positioned to illuminate the windshield for raindrop detection, then raindrop detection accuracy is improved, but brightness in the lower portion of the imaged area is reduced
Solution Approach 1:
Different regions of the image sensor are assigned different functional qualities: the first light-receiving portion maintains high light reception for general imaging and vehicle detection, while the second light-receiving portion is specifically configured to receive reflected illumination light for raindrop detection. This local differentiation allows each region to excel at its specific task without compromising the other.
Solution Approach 2:
The reflection polarization prism acts as an intermediary optical element that redirects illumination light onto the windshield and captures the reflected light. By positioning the prism to direct light paths appropriately, it enables raindrop detection functionality while the patent further introduces an optical member to prevent the prism from blocking light flux intended for the first light-receiving portion.
3Difficulty of detecting and measuring
If the reflection polarization prism is used to direct illumination light onto the windshield, then raindrop adhesion detection is improved, but light flux from the front area is interrupted
Solution Approach 1:
An optical member is introduced as an intermediary element positioned between the reflection polarization prism and the first light-receiving portion. This optical member specifically transmits light flux from the front area while blocking or redirecting the illumination light path, thereby preventing the prism from interrupting the light flux needed for the first light-receiving portion while still enabling raindrop detection functionality.
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 prevents a relative reduction in light reception at the first light-receiving portion close to the second light-receiving portion, enhancing the accuracy of image data and subsequent processing, such as vehicle detection and raindrop detection.
Implementation Method 1
The reflection polarization prism transmits the illumination light and is configured to be incident the illumination light on the windshield and to receive reflection light on the reflection polarization prism with the second light-receiving portion of the image sensor. By using the reflection polarization prism, it is possible to be made incident the illumination light on the inner wall surface of the wind shield to satisfy a condition in which the illumination light is totally reflected on an area (non-adhesion area) where the rain drop is not adhered on the outer wall surface of the windshield.
Implementation Method 2
an optical member like a wavelength filter, which allows illumination light to be directed to both the first and second light-receiving portions of the image sensor without interruption
Data Source
AI summary
An imaging device includes a reflection polarization prism having an incident surface on which illumination light emitted from a light emitter is incident and a transmission surface that passes the illumination light entered the incident surface through one surface of a light-transmitting member, an imager including an image sensor having a first light-receiving portion that receives light from a predetermined imaging area transmitting the light-transmitting member and a second light-receiving portion adjacent to the first light-receiving portion that receives the illumination light reflected on an opposite surface to the one surface of the light-transmitting member, and an optical member that emits the light introduced from the predetermined imaging area to the first light-receiving portion and emits the illumination light reflected on the opposite surface of the light-transmitting member to the second light-receiving portion.