Solid-State Imaging Device Pixel Control for Dynamic Range
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Solution Overview
Problem
The existing solid-state imaging devices have limited flexibility in setting charge accumulation periods for each pixel, which restricts the dynamic range of the device.
Innovation Solution
A solid-state imaging device with a photodetecting unit comprising M×N pixel units, each equipped with a photodiode, amplifying transistor, transfer transistor, readout transistor, first initialization transistor, and second initialization transistor, where one transistor performs on/off operations based on a row control signal and the other based on a column control signal, allowing for varied charge accumulation periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two transfer transistors connected in parallel are used with row and column control signals, then sensitivity and dynamic range can be variously set, but the degree of freedom in accumulation period setting is not sufficient
Solution Approach 1:
The patent divides the control of charge accumulation into two independent segments: one controlled by row control signals and the other by column control signals. Each segment can be independently adjusted, enabling flexible control of accumulation periods. This segmentation allows multiple discrete accumulation periods to be set for each pixel by combining different row and column control signal timings, thereby increasing the degree of freedom without requiring additional transistors.
Solution Approach 2:
The patent implements dynamic control of charge accumulation periods by making the accumulation timing adaptable through row and column control signals. The accumulation period can be dynamically adjusted for each pixel unit based on the timing of these control signals, allowing the system to respond to varying lighting conditions and capture requirements. This dynamic adjustment mechanism provides versatility in setting accumulation periods without increasing hardware complexity.
2Adaptability or versatility
If multiple discrete accumulation periods are set for each pixel, then dynamic range is widened, but device complexity increases
Solution Approach 1:
The row control signals and column control signals serve multiple functions: they control the transfer transistors for charge transfer, initialize the photodiode and amplifying transistor, and determine the accumulation period timing. By making these control signals multi-functional, the patent achieves wide dynamic range through multiple discrete accumulation periods without requiring separate dedicated control circuits for each function, thereby avoiding excessive device complexity.
Solution Approach 2:
The row and column control signals act as intermediaries that coordinate the timing of multiple operations (charge transfer, initialization, and accumulation) across different pixel units. These intermediary control signals enable the system to implement multiple discrete accumulation periods by combining different signal timing patterns, achieving enhanced dynamic range while keeping the control architecture relatively simple and modular.
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 configuration enables the setting of multiple discrete accumulation periods for each pixel, thereby widening the dynamic range and improving sensitivity and image capture capabilities, especially for images with varying luminance.
Implementation Method 1
a photodiode that generates a charge of an amount according to an incident light amount
Data Source
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AI summary
A solid-state imaging device includes a photodetecting unit, a row control unit, a column control unit, and a signal readout unit. The photodetecting unit includes M×N pixel units P(1,1) to P(M,N) two-dimensionally arrayed in M rows and N columns. Each pixel unit P(m,n) includes a photodiode PD, an amplifying transistor Tr1, a transfer transistor Tr2, a readout transistor Tr3, a first initialization transistor Tr4, and a second initialization transistor Tr5. One of the transfer transistor Tr2 and the first initialization transistor Tr4 performs an on/off operation based on a control signal output from the row control unit, and the other performs an on/off operation based on a control signal output from the column control unit. Thus, a solid-state imaging device capable of setting an accumulation period of various patterns different for each pixel is realized.