Solid-State Imaging Device Partial Discharge for High Frame Rate
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Solution Overview
Problem
Conventional solid-state imaging devices face challenges in achieving high frame rates due to potential variations in the p-well potential during thinning drive, leading to prolonged read and reset operations.
Innovation Solution
The implementation of a solid-state imaging device with first-group and second-group pixels, where charge is left behind in photoelectric conversion elements of skipped pixels to prevent overflow and stabilize the p-well potential, allowing for incomplete discharge and reduced read and reset times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge is completely discharged from photoelectric conversion elements of skipped pixels to prevent false signals, then image quality is improved, but read and reset operation time increases, limiting frame rate
Solution Approach 1:
The patent applies partial discharge by controlling the reset switch to discharge only a portion of the charge from photoelectric conversion elements of skipped pixels, rather than completely emptying them. This partial discharge is sufficient to prevent charge overflow into adjacent pixels while avoiding the full time penalty of complete discharge, thus resolving the contradiction between image quality and operation speed
Solution Approach 2:
The patent changes the discharge parameter by controlling the duration and timing of the reset switch activation. Instead of maintaining the reset switch in a fixed state, the control section dynamically adjusts the discharge amount based on the thinning drive requirements, enabling optimized balance between preventing false signals and maintaining high frame rates
2Productivity
If pixels are thinned for reading to achieve high frame rate, then productivity is improved, but potential variation in p-well occurs, prolonging read and reset operations
Solution Approach 1:
The patent implements feedback control where the control section monitors the thinning drive operation and adjusts the reset switch timing accordingly. The control logic responds to the operational state of the imaging device, dynamically optimizing the discharge timing to maintain p-well potential stability while achieving high frame rates through pixel thinning
Solution Approach 2:
The patent applies preliminary action by activating the reset switch before charge overflow can occur in skipped pixels during thinning drive. By proactively discharging charge in advance, the system prevents potential instability in the p-well before it develops, allowing high frame rate operation without compromising potential stability
3Reliability
If reset switch is kept active to prevent charge overflow from skipped pixels, then reliability is improved, but operation speed decreases due to extended reset time
Solution Approach 1:
The patent applies partial action by activating the reset switch only for the minimum necessary duration to prevent charge overflow, rather than keeping it continuously active. This controlled, temporary activation is sufficient to prevent false signals while minimizing the impact on operation speed, resolving the contradiction between reliability and speed
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 prevents false signals and stabilizes the p-well potential, enabling high-speed operation with reduced smearing, blooming, and color mixing, while shortening the read and reset times for high-frame-rate imaging.
Implementation Method 1
each of the pixels including a photoelectric conversion element for converting a light signal to signal charge and accumulating the charge
Data Source
AI summary
A solid-state imaging device includes first-group pixels 41, second-group pixels 42 skipped during thinning drive, and a scanning section 13. The scanning section 13 drives each of the first-group pixels 41 to perform read operation of outputting the output signal and initializing the amount of the signal charge accumulated in the photoelectric conversion element to a first level, and also drives each of the second-group pixels 42 to perform discharge operation of initializing the amount of the signal charge accumulated in the photoelectric conversion element to a second level that is higher than the first level and lower than a saturation signal level of the photoelectric conversion element 12.