Solid-State Imaging Apparatus Dynamic Range Expansion via Multi-Readout
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Solution Overview
Problem
Existing solid-state imaging apparatuses face challenges in expanding dynamic range while maintaining synchronicity of carrier accumulation periods, particularly in still image photography, due to high dark currents in the floating diffusion region and holding capacitors, which restrict signal amplitude and lead to unsuitable dynamic range expansion signals.
Innovation Solution
The apparatus includes a photoelectric conversion unit, a carrier accumulation unit, and a readout unit that reads signals multiple times during a single accumulation period and resets the carrier after each reading, utilizing a holding capacitor to increase dynamic range and prevent dark current suppression, ensuring synchronicity between accumulation periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the accumulation period of the dynamic range expansion signal is made short to reduce dark current, then dark current is reduced, but the synchronicity of the photo diode signal and dynamic range expansion signal is harmed
Solution Approach 1:
The patent divides the accumulation period into multiple segments, reading out the dynamic range expansion signal multiple times during a single accumulation period of the photo diode. This segmentation allows the carrier accumulation unit to hold the signal without requiring a short accumulation period, thereby reducing dark current while maintaining synchronicity through multiple synchronized readout operations
Solution Approach 2:
The patent introduces a carrier accumulation unit as an intermediary between the photo diode and the readout circuit. This intermediary unit holds the carrier from the dynamic range expansion signal during the photo diode's accumulation period, enabling multiple readout operations without affecting the synchronicity of the original signals while reducing the impact of dark current
2Duration of action of moving object
If the accumulation period is long to capture still images like fireworks, then image quality is improved, but dark current increases and restricts signal amplitude
Solution Approach 1:
The patent segments the long accumulation period into multiple readout intervals, allowing the system to maintain a long accumulation period for capturing still images while performing multiple readout operations. This reduces the effective impact of dark current by distributing the readout across multiple shorter intervals without sacrificing the total accumulation time
Solution Approach 2:
The carrier accumulation unit acts as an intermediary that holds the carrier signal throughout the entire long accumulation period, enabling multiple readout operations without requiring the photo diode to be reset multiple times. This maintains the long accumulation period benefits while managing dark current through controlled readout intervals
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 expands the dynamic range by approximately five times compared to previous methods, reduces noise, and ensures synchronicity of signals, particularly beneficial for long-duration still images like fireworks, by reading and processing signals in the same accumulation period.
Implementation Method 1
a photoelectric conversion unit for generating a carrier by a photoelectric conversion and for accumulating the carrier generated
Data Source
AI summary
A solid-state imaging apparatus of a dynamic range enlarged by reading out a carrier accumulated in a carrier accumulation unit at a plurality of times during a single carrier accumulation time period.