Averaging Circuit for Solid-State Image Pickup Devices
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Solution Overview
Problem
High-pixel digital cameras face challenges in maintaining image quality due to increased power consumption and chip area, leading to difficulties in achieving high frame rates and causing moiré fringes when pixel thinning is employed.
Innovation Solution
A solid-state image pickup device with an averaging circuit that groups pixels to average signals accumulated in signal accumulation circuits, allowing for output of averaged signals, which reduces random noise and moiré fringes, thereby improving image quality without significant power consumption increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If pixel thinning is employed to reduce chip area, then chip area is reduced, but moiré fringes occur and image quality deteriorates
Solution Approach 1:
The patent combines signals from multiple pixels (specifically four pixels: first, second, third, and fourth pixels) into a single output signal through an averaging circuit. This merging approach allows the system to maintain effective resolution while reducing the physical chip area required, as multiple photodetectors share a common readout path. The combining of signals eliminates moiré fringes by preventing the formation of interference patterns that occur when individual pixels are thinned or removed.
Solution Approach 2:
The patent segments the pixel array into groups of four pixels that are read out sequentially rather than simultaneously. By dividing the reading process into time-multiplexed segments, the system can maintain the full pixel array on the chip while reducing the effective readout bandwidth requirements. This segmentation allows four pixels to be processed as a single unit, reducing the chip area needed for parallel readout circuits while preventing moiré fringe formation.
2Productivity
If high frame rate is achieved through increased power consumption, then frame rate is improved, but power consumption increases
Solution Approach 1:
The averaging circuit merges and averages signals from four pixels before output, which reduces the total number of signal readout operations required. Instead of reading out each pixel separately at high frame rates, the system reads out averaged signals from pixel groups, significantly reducing the bandwidth and power consumption of the readout circuitry while maintaining the ability to achieve high frame rates.
Solution Approach 2:
The patent implements a partial reading approach where only the averaged signal from four pixels is read out rather than reading all individual pixel signals. This partial action reduces the total number of readout operations by a factor of four, thereby reducing power consumption while still capturing the essential image information. The excessive action of averaging multiple pixels provides redundancy that enables lower power consumption without sacrificing frame rate.
3Area of stationary object
If pixel thinning is employed to reduce chip area, then chip area is reduced, but image quality deteriorates
Solution Approach 1:
The patent merges signals from four pixels into a single output signal through averaging, which maintains image quality by preserving the combined signal strength while reducing the effective chip area. The merging process ensures that the total light collection area is maintained even though the physical footprint is reduced, as four photodetectors work together to produce one output signal with equivalent signal-to-noise ratio.
Solution Approach 2:
The patent changes the parameter of signal processing by introducing an averaging circuit that processes signals from multiple pixels before output. This parameter change allows the system to maintain effective resolution and image quality while reducing the physical chip area, as the averaging operation optimizes the signal characteristics without requiring each individual pixel to be large or well-resolved.
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
The solution effectively suppresses moiré fringes and reduces random noise, enhancing image quality while maintaining low power consumption, even at high frame rates.
Implementation Method 1
a first substrate 101 including a unit pixel cell having a photoelectric conversion element
Data Source
AI summary
A solid-state image pickup device in which a first substrate and a second substrate including circuit elements forming pixels and disposed therein are electrically connected by a connection unit, may include an averaging circuit that averages signals accumulated in signal accumulation circuits respectively included in the two or more pixels that are pixels included in the same group and are averaging targets, and an output circuit that outputs the averaged signals from the pixels. The pixels may be classified into a plurality of groups and each group may include the plurality of pixels. The pixels may include photoelectric conversion elements disposed in the first substrate, and the signal accumulation circuits that are disposed in the second substrate and accumulate signals that are generated by the photoelectric conversion elements and are input via the connection unit.