Image Pickup Apparatus Exposure Control with Stepwise Gain Adjustment
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Solution Overview
Problem
Conventional image pickup apparatuses face challenges in suppressing luminance changes during motion with high shutter speed, often resulting in image degradation due to noise introduced by constant gain adjustments.
Innovation Solution
An image pickup apparatus with an image pickup device, an amplification unit, and a control unit that adjusts the electric charge accumulation time period and amplification factor in synchronization with changes in shutter speed, using a compensation gain to minimize luminance changes and restore the amplification factor to its original value in steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If exposure time is controlled using an electronic shutter with integral multiple of horizontal synchronous signal period, then shutter speed can be adjusted in discrete steps, but luminance changes significantly with each step change making it difficult to suppress luminance changes during motion
Solution Approach 1:
The patent changes the parameter of amplification factor in conjunction with exposure time adjustments. When exposure time is changed in discrete steps, the amplification factor is simultaneously adjusted to compensate for luminance changes, thereby maintaining stable output luminance despite discrete shutter speed changes.
Solution Approach 2:
The patent introduces dynamic adjustment of amplification factor that responds to changes in exposure time. The amplification factor is not fixed but varies dynamically based on the current exposure time setting, allowing continuous luminance control even when shutter speed changes in discrete steps.
2Stability of the object's composition
If gain is always added according to luminance of subject to suppress luminance changes, then luminance stability is improved, but noise in the image increases resulting in image degradation
Solution Approach 1:
The patent applies partial gain adjustment rather than always adding maximum gain. The amplification factor is adjusted only to the extent necessary to compensate for luminance changes caused by exposure time variations, avoiding excessive gain addition that would amplify noise and degrade image quality.
3Stability of the object's composition
If amplification factor is adjusted to compensate for exposure time changes, then luminance stability is improved, but the system complexity increases due to coordinated control of multiple parameters
Solution Approach 1:
The patent combines the control of exposure time and amplification factor into a unified exposure control mechanism. The control unit simultaneously manages both parameters based on the same luminance stabilization objective, reducing the need for separate independent control systems and simplifying the overall control architecture.
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 suppresses luminance changes during high shutter speed while minimizing image degradation, ensuring that the image quality is maintained by synchronizing gain adjustments with shutter speed changes.
Implementation Method 1
an image pickup device configured to accumulate electric charge corresponding to an amount of light incident on the image pickup device
Implementation Method 2
an amplification unit configured to amplify a signal obtained as a result of accumulating electric charge in the image pickup apparatus
Data Source
AI summary
An image pickup apparatus which is capable of suppressing changes in luminance during motion with high shutter speed while minimizing image degradation. An image pickup device accumulates electric charge corresponding to an amount of light incident thereon. An amplification unit amplifies a signal obtained as a result of accumulating electric charge in the image pickup apparatus. A control unit controls an electric charge accumulation time period in the image pickup device. An adjustment unit adjusts an amplification factor for the amplification unit. In a case where the control unit changes the electric charge accumulation time period while the image pickup device is repeatedly accumulating electric charge, the adjustment unit adjusts an amplification factor in accordance with the amount of change in the electric charge accumulation time period, and after adjustment, the adjustment unit brings the adjusted amplification factor close to an amplification factor before adjustment in steps.