Optical Filter Elements Equalized Reflected Light Color Ghosting

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Solution Overview

Problem

Ghosting issues arise when light attenuation filters are used in imaging optical systems, causing discomfort to photographers during filter switching due to changes in reflected light colors.

Innovation Solution

The solution involves a light amount adjusting device with optical filter elements having substantially equal reflected light colors, which reduces the perceived change in ghost color when switching filters, thereby minimizing photographer discomfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light attenuation filter is used to suppress light amount, then the opening diameter can be maintained, but ghost is readily formed causing discomfort to photographers

Engineering Contradiction:
Improvelight amount suppressionVSAvoidghost formation
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies color changes by designing optical filter elements with specific reflected light color characteristics. The filter elements are engineered to have reflected light colors that are substantially equal to each other, which transforms the harmful ghost effect into a less noticeable phenomenon by making the ghost color consistent and less distracting to photographers.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent changes the parameter of reflected light color by controlling the spectral characteristics of the optical filter elements. By adjusting the reflected light color parameters to be substantially equal across different filter elements, the patent reduces the visual impact of ghosting while maintaining the light attenuation function.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If multiple ND filters are provided and switched according to luminance, then light amount control is improved, but ghost color changes cause discomfort during switching

Engineering Contradiction:
Improvelight amount controlVSAvoidghost color change
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent systematically applies color changes by designing multiple optical filter elements with different light transmittances but substantially equal reflected light colors. This allows the system to switch between filters for different luminance conditions while maintaining consistent ghost color, thereby improving adaptability without the discomfort of changing ghost colors.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent creates equipotentiality in terms of reflected light color across different filter elements. By making the reflected light colors substantially equal, the patent ensures that switching between filters does not create noticeable changes in ghost color, providing a uniform visual experience across different operating conditions.

Inventive Principle:
Principle #12Equipotentiality

3Illumination intensity

If the opening diameter is reduced to suppress light, then light amount is controlled, but image quality degrades due to hunting phenomenon or diffraction

Engineering Contradiction:
Improvelight amount controlVSAvoidimage quality
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent introduces an intermediary solution by using optical filter elements with controlled reflected light colors. These filters act as mediators that allow light amount suppression without requiring reduction of the opening diameter, thereby avoiding the hunting phenomenon and diffraction effects that would otherwise degrade image quality.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 approach effectively reduces the sense of discomfort caused by ghosting by ensuring that the reflected light colors of the optical filter elements remain consistent, even when switching, resulting in a more stable imaging experience.

Implementation Method 1

reflected light colors of the optical filter elements substantially equal

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2894513B1Light intensity adjusting device, imaging optical system, and imaging device
Publication Date: 2023.04.26 CANON DENSHI KK
  • EP2894513B1 patent drawingFigure 1~2
  • EP2894513B1 patent drawingFigure 3~4
  • EP2894513B1 patent drawingFigure 5A~5C

AI summary

This invention reduces a sense of discomfort that a ghost gives to a photographer when switching an optical filter in accordance with the luminance of an object. A light amount adjusting device includes a plurality of optical filter elements having different light transmittances. The plurality of optical filter elements have substantially equal reflected light colors.