Scanner Mirror Angular Offset Stabilizes Light Reception

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Solution Overview

Problem

The existing ranging devices using vibrating mirror modules with light receiving mirrors aligned in the same plane experience significant fluctuations in light reception, leading to inconsistent measurement accuracy due to varying effective light receiving surface areas as the mirrors pivot, resulting in pronounced differences in signal-to-noise ratios.

Innovation Solution

The proposed solution involves a scanner mirror configuration with first and second reflectors having light receiving faces that are angularly offset about a pivot axis, allowing them to pivot together while maintaining a relative positional relationship, ensuring a consistent effective light receiving surface area and reducing light reception fluctuations, with optimal offset angles between 75 to 105 degrees, particularly 90 degrees, to stabilize the signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If two light receiving mirrors are aligned in the same plane and pivoted together, then the light receiving surface area increases, but the effective light receiving surface area fluctuates significantly during scanning

Engineering Contradiction:
Improvelight receiving surface areaVSAvoidmeasurement accuracy
Core Design Contradiction:
Area of stationary objectVSMeasurement precision

Solution Approach 1:

The light receiving mirror is divided into two separate reflectors (first reflector and second reflector) that are angularly offset from each other. Each reflector independently receives light from different angular positions, preventing the effective receiving area from fluctuating during scanning. This segmentation resolves the contradiction by maintaining a constant effective light receiving area while improving measurement precision.

Inventive Principle:
Principle #1Segmentation

2Use of energy by moving object

If two light receiving mirrors are aligned in the same plane, then the light receiving capability is enhanced, but the signal-to-noise ratio fluctuates during scanning

Engineering Contradiction:
Improvelight receiving capabilityVSAvoidsignal-to-noise ratio
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

By dividing the light receiving function into two angularly offset reflectors, each reflector maintains a stable effective receiving area during scanning. This prevents the signal-to-noise ratio from fluctuating, thereby enhancing reliability while preserving light receiving capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each reflector is positioned at a specific angular offset to receive light from particular directions. This local specialization ensures that at any scanning angle, at least one reflector maintains optimal light reception, stabilizing the signal-to-noise ratio throughout the scanning range.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If light receiving mirrors are displaced during scanning, then the scanning function is achieved, but the effective light receiving surface area repeatedly increases and decreases

Engineering Contradiction:
Improvescanning functionVSAvoideffective light receiving surface area
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

The scanning function is achieved by displacing two angularly offset reflectors simultaneously. Their angular offset ensures that as one reflector's effective area decreases during scanning, the other's increases, maintaining a constant total effective light receiving area.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The two reflectors are positioned asymmetrically with an angular offset (preferably 90 degrees) between them. This asymmetric arrangement ensures that their effective receiving areas complement each other during scanning, preventing fluctuations while maintaining the scanning function.

Inventive Principle:
Principle #4Asymmetry

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 significantly reduces the fluctuation range of light received by the photodetector, enhancing measurement accuracy and uniformity across the pivot angle range by ensuring that the light receiving surface areas complement each other, thereby stabilizing the signal-to-noise ratio.

Implementation Method 1

a scanner mirror including a reflecting mirror having first and second reflectors that are pivotally arranged about a pivot axis, the first and second reflectors having light receiving faces, respectively

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3290987B1Ranging device comprising a scanner mirror
Publication Date: 2019.09.25 FUNAI ELECTRIC CO LTD
  • EP3290987B1 patent drawingFigure 1
  • EP3290987B1 patent drawingFigure 2~3
  • EP3290987B1 patent drawingFigure 4~5

AI summary

A scanner mirror (30) includes a reflecting mirror (50) and a driver. The reflecting mirror (50) has first (51) and second reflectors (52) that are pivotally arranged about a pivot axis (150). The first and second reflectors have light receiving faces, respectively. The light receiving faces face in directions that are angularly offset with each other about the pivot axis (150). The driver is configured to drive the reflecting mirror (50) to pivot the first and second reflectors within a specific angle range.