Image Sensor Current Summing for Low-Power Pixel Signal Addition
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Solution Overview
Problem
Existing image sensor technologies face challenges in efficiently adding pixel signals while minimizing noise and reducing power consumption, particularly when converting signals from multiple pixels.
Innovation Solution
The image sensor employs a configuration with multiple sample-and-hold circuits, converters, and a switch that allows for the addition or independent output of currents corresponding to pixel signals, thereby reducing noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel signals are converted to digital signals and then added, then signal addition can be performed, but power consumption increases
Solution Approach 1:
The patent changes the parameter domain of signal processing from digital to analog current domain. By converting pixel signals to current signals and performing addition in the current domain rather than digital domain, the patent reduces power consumption while maintaining signal addition capability. The converter circuits transform voltage signals to current signals, enabling low-power analog addition operations.
2Device complexity
If multiple pixels share a vertical output line, then device complexity is reduced, but signal addition becomes difficult
Solution Approach 1:
The patent introduces sample-and-hold circuits as intermediary components between the vertical output line and the addition operation. These circuits temporarily store signals from multiple pixels, enabling subsequent addition operations without requiring complex real-time switching arrangements. This intermediary approach maintains simple shared output line architecture while enabling flexible signal addition.
3Quantity of substance
If signals are sampled and held in capacitors, then signal storage is achieved, but noise from reset signals is introduced
Solution Approach 1:
The patent extracts the reset signal component from the pixel signal before the addition operation. By separately sampling and holding reset signals and optical signals, then subtracting the reset component from the optical signal, the patent removes harmful reset noise while preserving the desired image information. This extraction approach isolates and eliminates the harmful reset noise component.
4Adaptability or versatility
If pixel signals are output independently, then signal processing flexibility is maintained, but power consumption increases
Solution Approach 1:
The patent merges multiple pixel signals into a single current signal through addition operations. By combining signals from multiple pixels into one aggregated current signal that can be processed by a single ADC, the patent reduces the number of active circuits and power-consuming operations while maintaining processing flexibility through selective addition control via switches.
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 enables efficient signal addition across multiple pixels with reduced noise and power consumption, enhancing image quality and performance.
Implementation Method 1
a plurality of converters that convert the signals held in the plurality of sample-and-hold circuits to currents corresponding to potentials of the signals
Data Source
AI summary
An image sensor comprises: a plurality of sample-and-hold circuits that sample and hold a plurality of signals input from a plurality of different pixels; a plurality of converters that convert the signals held in the plurality of sample-and-hold circuits to currents corresponding to potentials of the signals, respectively; a switch that connects/disconnects the plurality of converters; and a plurality of output circuits wherein, in a case where the switch connects the plurality of converters, the currents converted by the plurality of converters are added and output from one of the plurality of output circuits, and, in a case where the switch disconnects the plurality of converters, the currents converted by the plurality of converters are output from the plurality of output circuits, respectively.