Variable Gain Amplifier for High Dynamic Range Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current image pickup devices using linear sensors face limitations in dynamic range, leading to inaccurate photometry, especially in high-contrast situations, and existing solutions either require multiple preliminary light emissions or compromise live view functionality and resolution.
Innovation Solution
An image pickup device with a pixel array, amplifier unit, and gain-setting unit that allows for multiple gain settings, enabling pixel signals to be amplified and read out with different gains during a single exposure, expanding the dynamic range and enabling accurate photometry without degrading resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple preliminary light emissions are performed to expand dynamic range, then photometric accuracy is improved, but release time lag increases
Solution Approach 1:
The patent changes the gain parameter of the amplifier to achieve multiple amplification levels (e.g., 1x, 2x, 4x) from a single pixel signal. By varying the amplifier gain instead of performing multiple exposures, the system expands the measurable dynamic range while maintaining a single exposure time, thus eliminating release time lag.
Solution Approach 2:
The patent segments the amplification process into multiple gain stages within a single exposure. The pixel signals are read out once and then processed through different amplification levels, effectively creating multiple measurement ranges from one exposure event, thereby avoiding the need for multiple preliminary light emissions.
2Measurement precision
If pixel summation method is used to expand dynamic range, then dynamic range is improved, but resolution degrades
Solution Approach 1:
Instead of summing multiple pixel signals (which degrades resolution), the patent changes the amplification parameter of the read-out amplifier. This allows the same single pixel signal to be amplified at different levels, expanding dynamic range without any loss of spatial resolution or photometric accuracy.
3Speed
If thinning-out reading is performed to speed up read-out, then read-out speed is improved, but resolution degrades
Solution Approach 1:
The patent uses amplifier gain variation instead of thinning-out pixel read-out. This maintains full-resolution pixel signal read-out while still achieving high-speed processing through electronic amplification control, thereby preserving both resolution and read-out speed.
4Device complexity
If single gain amplification is used, then device complexity is reduced, but dynamic range is limited
Solution Approach 1:
The patent introduces dynamic gain control into the amplifier, allowing the gain level to be adjusted based on the brightness conditions. This dynamic adaptation enables the single amplifier to handle a wide dynamic range by automatically selecting appropriate amplification levels, maintaining device simplicity while expanding measurement capability.
Solution Approach 2:
The amplifier's gain parameter is made variable with multiple predetermined levels. This parameter change capability allows the same hardware amplifier to function across multiple dynamic ranges, effectively multiplying the measurable light intensity range without adding multiple physical amplifiers.
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 allows for accurate photometry with one-time exposure, expanding the dynamic range and maintaining high resolution, even in high-luminance conditions, while supporting live view functionality.
Implementation Method 1
a pixel array formed by a plurality of pixels including photoelectric conversion elements
Implementation Method 2
an amplifier unit configured to be capable of having at least two gains set therein, and amplify and output the pixel signals
Data Source
AI summary
An image pickup device which makes it possible to expand the dynamic range of photometry. The image pickup device comprises a pixel array, a pixel reader, a row selector, a column selector, a gain circuit, a gain selector. The pixel array comprises a plurality of pixels including photoelectric conversion elements and arranged in the horizontal direction and in the vertical direction. The pixel reader reads out selected pixel signals from the pixel array. The gain circuit is capable of having at least two gains set therein, and amplifies and outputs the pixel signals read out from the pixel array by the pixel reader. The gain selector sets different gains in the gain circuit such that pixel signals amplified by the different gains can be obtained for one-time read-out from the pixel array by the pixel reader.