Image Pickup Apparatus Day-Night Mode Switching Control
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Solution Overview
Problem
Existing image pickup apparatuses experience mode switching instability, known as 'hunching,' when transitioning between day and night modes due to varying luminance conditions, often resulting in inappropriate mode selection and increased costs from additional optical sensors.
Innovation Solution
An image pickup apparatus that uses an image sensor and processor to determine the ratio of infrared and visible light based on image signals, setting conditions for optimal mode switching between day and night modes by analyzing the ratios and adjusting the infrared cut filter's position in the optical path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the infrared cut filter is extracted from the optical path to increase sensitivity in low luminance state, then sensitivity is improved, but color balance collapses and mode switching instability (hunching) occurs
Solution Approach 1:
The patent uses feedback by continuously monitoring the luminance signal from the image sensor and comparing it against threshold values to dynamically control the infrared cut filter extraction. The system determines whether to extract or insert the filter based on the current luminance level, creating a closed-loop control system that adapts to changing lighting conditions and prevents hunching by making switching decisions based on real-time feedback rather than fixed thresholds.
Solution Approach 2:
The patent implements dynamic switching control by using variable threshold values that change based on the current operating mode. When in day mode, a first threshold is used for switching to night mode, and when in night mode, a second threshold (different from the first) is used for switching back to day mode. This dynamic threshold adjustment prevents oscillation around a single threshold value and stabilizes mode transitions.
2Reliability
If a threshold is set to prevent hunching, then mode switching stability is improved, but the photographing in night mode continues without switching to day mode even when object luminance rises
Solution Approach 1:
The patent applies dynamics by implementing different threshold values for different switching directions. The first threshold controls switching from day mode to night mode, while the second threshold controls switching from night mode to day mode. This asymmetric threshold design allows the system to be stable in preventing hunching while remaining adaptable to luminance changes in both directions, ensuring timely mode transitions when appropriate.
3Reliability
If an optical sensor is added for photometry of visible light only, then auto day-night function stability is improved, but the cost of the image pickup apparatus rises
Solution Approach 1:
The patent applies universality by making the image sensor serve multiple functions: it acts as both the primary imaging device and the photometric sensor for detecting luminance levels. By utilizing the luminance signal already generated by the image sensor for mode switching decisions, the system eliminates the need for a separate optical sensor, reducing cost while maintaining the stability of the auto day-night function.
Solution Approach 2:
The patent merges the photometric function into the existing image sensor system. Instead of having separate imaging and photometry components, the system combines these functions by using the luminance signal from the image sensor for both image formation and luminance-based mode switching control, thereby reducing component count and cost.
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
Prevents hunching and ensures timely switching between day and night modes at a lower cost without the need for additional sensors, maintaining accurate mode selection under various lighting conditions.
Implementation Method 1
an image sensor which outputs an image signal depending on an optical image formed through an image pickup optical system
Implementation Method 2
an infrared cut filter for correcting a visual sensitivity in front of an image sensor. The infrared cut filter blocks out light in a near-infrared range
Data Source
AI summary
An image pickup apparatus that is capable of preventing hunching certainly at low cost and of switching between the day mode and the night mode at an optimal timing. An image sensor outputs an image signal depending on an optical image formed through an image pickup optical system. A mode setting unit sets a photographing mode for photographing using the image sensor from among a day mode and a night mode in which sensitivity for a wavelength range corresponding to infrared light is higher than that in the day mode. An obtaining unit obtains ratio information about the ratios of the infrared light and visible light based on the image signal in the night mode. A condition setting unit sets a determination condition that is used for switching the photographing mode to the day mode from the night mode based on the ratio information.