Diaphragm-Integrated IR-Cut Filter for Camera Mode Transition

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Solution Overview

Problem

Existing camera IR-filter arrangements suffer from flickering between night and day modes due to low light levels during transitions, causing poor image quality and wear on actuators, and current solutions like light sensors do not fully address these issues.

Innovation Solution

A fixed bandpass IR filter and an IR-cut filter integrated within the camera's diaphragm, where the diaphragm's aperture adjustment controls the relative coverage by the IR-cut filter, allowing seamless transitions between modes without a movable IR-cut filter, enabling more radiation to reach the image sensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a movable IR-cut filter is used to switch between day and night modes, then color image quality is improved during daytime, but the actuator experiences wear and flickering occurs during mode transitions

Engineering Contradiction:

Improveimage quality stabilityVSAvoidactuator lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent combines the IR-cut filter with the diaphragm structure, merging two separate components (filter and aperture control) into a single integrated unit. This eliminates the need for a separate movable IR-cut filter actuator, thereby reducing mechanical wear while maintaining the ability to switch between day and night modes through diaphragm aperture adjustment.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The diaphragm is given dual functionality: it serves both as the aperture control for exposure and as the mounting structure for the IR-cut filter. By making the diaphragm universal, the patent eliminates the need for a dedicated movable filter mechanism, reducing actuator wear while preserving mode-switching capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a movable IR-cut filter is used for mode switching, then color balance is maintained during daytime, but light level drops too low during transition causing flickering

Engineering Contradiction:

Improvecolor balance stabilityVSAvoidlight level during transition

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent employs continuous aperture adjustment of the diaphragm rather than discrete on/off switching. This dynamic control allows gradual transition between modes, maintaining sufficient light levels throughout the transition process and eliminating flickering while preserving color balance through the integrated IR-cut filter.

Inventive Principle:

Principle #15Dynamics

3Productivity

If an IR-cut filter is completely removed during night mode, then IR radiation detection is maximized, but the filter mechanism adds complexity and potential failure points

Engineering Contradiction:

ImproveIR radiation detection efficiencyVSAvoidfilter mechanism complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

By integrating the IR-cut filter into the diaphragm structure, the patent eliminates the need for a separate filter mounting mechanism and actuator. This simplification reduces device complexity and potential failure points while maintaining the ability to fully remove the filter from the optical path during night mode for maximum IR radiation detection.

Inventive Principle:

Principle #5Merging (Combining)

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 solution eliminates the need for a movable IR-cut filter, reduces artifacts, and allows for smooth transitions between day and night modes, improving image quality and extending the lifespan of camera components.

Implementation Method 1

a fixedly arranged bandpass IR filter (106) allowing transmission of radiation only in a defined spectral region

Methodology Applied

Scientific EffectBandpass filtering: Filter (optical)

Implementation Method 2

an IR-cut filter (112) arranged to block any IR wavelength transmitted by the fixed band-pass filter

Methodology Applied

Scientific EffectIR wavelength blocking: Absorption (EM radiation)

Implementation Method 3

the diaphragm's aperture adjustment controls the relative coverage by the IR-cut filter, allowing seamless transitions between modes

Methodology Applied

Scientific EffectAperture control:

Implementation Method 4

the image sensor of the camera has a spectral response with a non-negligible component in the infrared

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS10386554B2IR-filter arrangement

Publication Date: 2019.08.20 AXIS

AI summary

An infrared (IR) filter arrangement for a camera having an associated IR illuminator, the arrangement comprising: a fixedly arranged bandpass IR filter filtering out IR frequencies other than those from the IR illuminator; and an IR cut filter at least blocking any IR wavelength transmitted by the fixed band-pass filter, the IR filter being integrated in a diaphragm of the camera, such that closing of the diaphragm aperture entails an increased relative proportion of the diaphragm aperture being covered by the IR cut filter, and opening of the diaphragm aperture entails a decreased relative proportion of the diaphragm aperture being covered by the IR cut filter.