Imaging System Day/Night Switching With ND Filter Threshold Correction
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Solution Overview
Problem
Imaging apparatuses face challenges in accurately switching between day and night modes under varying infrared light conditions, particularly in environments with significant infrared light, leading to mode hunting and loss of color balance.
Innovation Solution
An imaging apparatus that includes a processor to acquire a parameter related to subject brightness, determine filter insertion based on predetermined conditions, and correct thresholds for mode switching based on the ND filter's transmittance, ensuring robust mode transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the infrared cut filter is removed to increase sensitivity in low illuminance conditions, then the sensitivity is improved, but the color balance is lost due to near-infrared light passage
Solution Approach 1:
The patent changes the parameter of the switching threshold based on the transmittance characteristics of the ND filter. When an ND filter is inserted, the threshold for switching between day and night modes is adjusted to account for the filter's effect on light transmission, particularly in the near-infrared region. This ensures accurate mode switching regardless of the ND filter's presence or transmittance value.
2Measurement precision
If the switching threshold is corrected based on maximum gain, then the mode switching timing is improved, but the correction is insufficient in environments with significant infrared light
Solution Approach 1:
The patent introduces a correction mechanism that adjusts the switching threshold based on the ND filter's transmittance characteristics. The correction amount is determined by the ND filter transmittance, which directly affects how much near-infrared light passes through. This parameter change approach allows the system to compensate for the ND filter's impact on brightness measurement, enabling stable mode switching even in environments with significant infrared light.
3Measurement precision
If the switching threshold is corrected based on the amount of infrared light, then the mode switching accuracy is improved, but the system complexity increases
Solution Approach 1:
The patent uses the ND filter transmittance as an intermediary parameter to correct the switching threshold. Instead of directly measuring infrared light amounts, the system uses the known transmittance characteristics of the ND filter (which is already controlled by the exposure control unit) to infer and correct for infrared light effects. This intermediary approach achieves accurate correction without requiring additional infrared sensors or complex measurement mechanisms.
4Measurement precision
If the ND filter transmittance is considered in threshold correction, then the mode switching accuracy is improved, but the device complexity increases
Solution Approach 1:
The system uses information already available within the exposure control unit (the ND filter transmittance setting) to perform the threshold correction. The exposure control unit, which already manages the ND filter for exposure purposes, also provides the transmittance information needed for mode switching correction. This self-service approach allows the mode switching function to benefit from existing data without requiring separate measurement systems or additional hardware complexity.
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
Enables precise and timely switching between day and night modes, maintaining image quality and color balance by accounting for ND filter transmittance, reducing mode hunting and noise-related issues.
Implementation Method 1
an imaging apparatus generally includes, in front of an imaging element, an infrared cut filter for correction of vision sensitivity that does not pass light rays in the near-infrared region
Implementation Method 2
the transmittance (degree of dimming) of light of an optical filter such as a neutral density (ND) filter
Data Source
AI summary
An imaging apparatus includes at least one processor, and a memory coupled to the at least one processor. The memory stores instructions that, when executed by the at least one processor, cause the at least one processor to acquire a parameter related to a brightness of a subject; determine whether to insert a first filter configured to attenuate infrared light into a light path of an imaging optical system, based on whether the acquired parameter satisfies a predetermined condition; and correct the predetermined condition based on whether a second filter different from the first filter and configured to attenuate light is inserted into the light path of the imaging optical system.