Optical System Wide Angle Resolution

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Solution Overview

Problem

Conventional optical systems that capture images at wide view angles suffer from image compression at the periphery, leading to lost information and reduced angular resolution, particularly at maximum view angles, making it difficult to maintain high image quality and resolution across the entire capture range.

Innovation Solution

The optical system is designed such that the rate of change of image height per view angle is greater than 0 at the maximum view angle, with a specific expression for the rate of change of view angle per image height, ensuring increased angular resolution across the entire image capture range while allowing for a wide view angle capture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If orthogonal projection method is used to capture wide view angle images, then the image capture range is widened, but the periphery of the image becomes compressed and information is lost

Engineering Contradiction:
Improveimage capture rangeVSAvoidinformation loss at periphery
Core Design Contradiction:
Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent changes the projection characteristics from conventional orthogonal projection (y = f·sinθ) to a new projection method expressed by y = a·f·sin(b·θ), where parameters a and b are optimized to maintain dy/dθ > 0 at maximum view angle. This parameter modification transforms the projection geometry to prevent periphery compression while preserving wide-angle capture capability.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If conventional optical systems are used for wide view angle capture, then the view angle is widened, but the angular resolution deteriorates at maximum view angle

Engineering Contradiction:
Improveview angleVSAvoidangular resolution
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent modifies the projection function parameters to ensure dy/dθ > 0 at the maximum view angle θmax. By optimizing parameters a and b in the expression y = a·f·sin(b·θ), the system maintains positive rate of change of image height per view angle even at maximum view angle, thereby preserving angular resolution across the entire field of view.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a dynamic projection system where the rate of change dy/dθ is maintained positive throughout the view angle range. This dynamic characteristic ensures that the optical system adapts to maintain resolution quality across varying view angles, particularly preventing the resolution collapse that occurs at maximum view angle in conventional systems.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If perspective projection method is used, then the image quality at center is maintained, but the image height diverges at wide angle requiring infinitely large imaging element

Engineering Contradiction:
Improveimage quality at centerVSAvoidimaging element size
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent transitions from perspective projection (y = f·tanθ) to a modified projection method (y = a·f·sin(b·θ)) that combines advantages of both perspective and orthogonal projections. The parameter b controls the projection curvature to maintain center image quality while parameter a scales the overall image height to remain finite at wide angles, eliminating the need for infinitely large imaging elements.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3214474B1Optical system, image capturing device and distance measuring system
Publication Date: 2019.07.24 HITACHI AUTOMOTIVE SYST LTD
  • EP3214474B1 patent drawingFigure 1
  • EP3214474B1 patent drawingFigure 2
  • EP3214474B1 patent drawingFigure 3

AI summary

Provided is a technology which is suitable for both widening an image capture view angle and securing an angular resolution across the entire image capture range. In an imaging optical system, a rate of change of an image height per view angle, i.e. dy/dθ, is greater than 0 at a maximum view angle θmax, a rate of change of a view angle per image height, i.e. D(θ) = 1/(dy(θ)/dθ), satisfies an expression D(θp) > {(D(θmax) - D(0))/θmaxθ}θp + D(0), with θp which lies in a range of 0 < θ < θmax, and it satisfies an expression 1.5 < (y(θs)/θs)/{(y(θmax) - y(θs))/(θmax - θs)} < 3.0 with a switching view angle θs of the rate of change D(θ) of the view angle per image height.