Solid State Imaging Pixel Row Selection Redundancy
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Solution Overview
Problem
In solid-state imaging devices, failures in row selection lines, such as disconnection or short circuits, prevent the proper operation of switch circuits, leading to charge accumulation and abnormal output in affected and adjacent rows, making it difficult to read out charges from pixels.
Innovation Solution
The device incorporates two switch circuits per pixel connected in parallel to readout lines and separate row selection lines, with a shift register providing a common row selection signal to ensure at least one switch circuit operates even if a row selection line fails, and buffers are used to prevent signal failure from affecting adjacent lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single row selection line is used to control switch circuits in each pixel, then the device complexity is reduced, but the reliability deteriorates when the row selection line fails due to disconnection or short circuit
Solution Approach 1:
The patent applies local quality by providing different configurations to different parts of the pixel array. Specifically, pixels in the first through (M-1)-th rows have both first and second switch circuits with separate row selection lines, while pixels in the M-th row have only first switch circuits. This localized differentiation allows the system to achieve redundancy where needed while maintaining simplicity elsewhere, resolving the contradiction between device complexity and reliability.
Solution Approach 2:
The patent implements beforehand cushioning by pre-configuring dual switch circuits and separate row selection lines for pixels in rows 1 to M-1. This redundant structure is prepared in advance to cushion against potential failures of row selection lines or switch circuits. When a failure occurs, the backup path ensures continuous operation, thus preventing charge accumulation and spill-over before they can affect image quality.
2Reliability
If dual switch circuits with separate row selection lines are provided for each pixel, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by providing different configurations to different parts of the pixel array. Specifically, pixels in the first through (M-1)-th rows have both first and second switch circuits with separate row selection lines, while pixels in the M-th row have only first switch circuits. This localized differentiation allows the system to achieve redundancy where needed while maintaining simplicity elsewhere, resolving the contradiction between device complexity and reliability.
Solution Approach 2:
The patent applies partial or excessive action by providing redundant switch circuits and row selection lines for only (M-1) out of M rows. This partial redundancy is sufficient to prevent charge spill-over failures while avoiding the excessive complexity of duplicating the entire pixel array structure. The redundancy is applied to the extent necessary to solve the reliability problem without over-engineering the system.
3Reliability
If shift registers are provided at both ends of the row selection line to supply signals from both sides, then the reliability is improved, but the device complexity and signal interference risk increase
Solution Approach 1:
The patent applies segmentation by dividing the row selection signal supply function into separate segments. Instead of using a single shared shift register for the entire row selection line, the patent provides separate shift registers for the first and second row selection lines. This segmentation isolates potential failure points and prevents signal interference between the two selection lines, resolving the contradiction between reliability and complexity by distributing the function across independent units.
Solution Approach 2:
The patent applies the intermediary principle by introducing separate shift registers as intermediary devices between the signal source and the row selection lines. These shift registers act as independent mediators that can supply row selection signals without interfering with each other, even when failures or short circuits occur in the row selection lines themselves, thus improving reliability while maintaining manageable 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
This configuration allows for the successful readout of charges from each pixel even when a row selection line fails, preventing charge spill-over and maintaining image data integrity.
Implementation Method 1
a photodiode for converting light incident thereon into an electron is arranged in each pixel
Data Source
Figure 1
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AI summary
A solid-state imaging device 1A includes a photodetecting section 20, a vertical shift register section 60A, first row selection lines QA1 to QAM, and second row selection lines QB1 to QBM. The vertical shift register section 60A provides the row selection lines QAm and QBm of the m-th row with common row selection signals VSAm and VSBm. This realizes a solid-state imaging device which can read out charges from each pixel even when a row selection line fails.