Solid-State Imaging Device Optical Black Gray Units
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Solution Overview
Problem
Existing solid-state imaging devices face challenges in real-time correction of offset and gain variations in output signals, particularly due to temperature changes and limitations in signal correction methods, leading to vertical stripes in images.
Innovation Solution
Incorporating optical black units and optical gray units with photoelectric conversion elements and amplifying units, along with a correction circuit that uses reference voltages to generate output signals in dark and intermediate states, allowing for real-time correction of offset and gain variations across pixel units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction data is acquired in advance before imaging operation, then offset and gain variations can be compensated, but temperature changes after imaging starts make correction insufficient
Solution Approach 1:
The patent applies preliminary action by acquiring correction data in advance through optical black units and optical gray units before the imaging operation starts. These units capture reference signals during a dark state and intermediate state, respectively, allowing offset and gain variations to be compensated before actual imaging begins. This preliminary correction addresses the technical contradiction by preparing correction data in advance while the imaging device is still in a stable thermal state.
2Measurement precision
If gain is set indirectly from reset level, then offset correction is achieved, but correction is ineffective in portions not related to reset level and gain
Solution Approach 1:
The patent applies segmentation by dividing the correction process into distinct segments handled by different units: optical black units for offset correction (dark state), optical gray units for gain correction (intermediate state), and pixel units for actual imaging. This segmentation allows each unit to specialize in specific correction aspects, achieving both offset and gain correction effectively across different signal levels.
Solution Approach 2:
The patent applies parameter changes by utilizing different signal levels (dark state and intermediate state) to correct different parameters. The optical black unit operates at a dark state level to correct offset, while the optical gray unit operates at an intermediate state level to correct gain. By changing the operating parameter (signal level), the system achieves comprehensive correction coverage.
3Measurement precision
If reference voltage is supplied to one column at boundary, then correction data can be acquired, but vertical stripes occur due to offset and gain variations between columns
Solution Approach 1:
The patent applies universality by making the optical black units and optical gray units functionally equivalent to pixel units in terms of structure (same photoelectric conversion element and amplifying unit). This multi-functionality allows these reference units to serve dual purposes: providing correction data for their own column and enabling correction of offset and gain variations across all columns, thereby preventing vertical stripe artifacts.
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
Enables real-time correction of offset and gain variations, reducing vertical stripes and improving image quality by using optical black and gray units to generate reference signals for pixel units, thereby simplifying the initial correction process and enhancing imaging accuracy.
Implementation Method 1
pixel units each of which has a photoelectric conversion element
Data Source
AI summary
A solid-state imaging device 1 according to an embodiment of the invention includes: pixel units P(x, y) each of which includes a photoelectric conversion element and an amplifying unit for a pixel unit and which are two-dimensionally arranged; at least one row of optical black units Pob(x, y) each of which includes a photoelectric conversion element, an amplifying unit for a pixel unit, and a light shielding film that covers the photoelectric conversion element, the photoelectric conversion element and the amplifying unit for a pixel unit being the same as those of the pixel unit P(x, y); and at least one row of optical gray units Pog(x, y) each of which includes an amplifying unit for a pixel unit which is the same as that of the pixel unit and to which a reference voltage is input. The value of the reference voltage is less than the value of the output signal from the photoelectric conversion element in a saturated state.