Image Sensor Current Summing for Low-Power Noise Suppression
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Solution Overview
Problem
Existing image sensor technologies consume high power when converting pixel signals into digital signals and do not effectively add signals from multiple pixels while suppressing noise.
Innovation Solution
An image sensor with a plurality of sample-and-hold circuits, converters, and switches that allow for adding or independently outputting currents corresponding to pixel signals, reducing power consumption and noise influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel signals are converted to digital signals and then added, then signal addition is achieved, 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 achieves signal addition while reducing power consumption, as analog current addition requires less energy than digital conversion and processing
Solution Approach 2:
The patent introduces current signals as an intermediary form between voltage signals and digital signals. The signal processing chain becomes: voltage signal → current signal (via converter) → current addition (via adder) → output, where the current signal serves as an intermediate representation that enables low-power addition operations
2Object-affected harmful factors
If signals from multiple pixels are added, then noise suppression is improved, but circuit complexity increases
Solution Approach 1:
The patent merges multiple pixel signals into a single added output signal through current addition. By combining signals from multiple pixels in the analog current domain using simple current adders rather than digital processing, the patent achieves noise suppression through signal averaging while maintaining relatively simple circuit architecture
Solution Approach 2:
The patent replaces complex digital signal processing mechanisms with simpler analog current addition mechanisms. Instead of using digital converters, processors, and algorithms for signal addition and noise suppression, the patent uses direct analog current addition circuits that are simpler in structure and operation
3Duration of action of stationary object
If sample-and-hold circuits are used for each pixel, then signal holding capability is improved, but device area increases
Solution Approach 1:
The patent makes the sample-and-hold functionality universal by sharing a single sample-and-hold circuit among multiple pixels. The same sample-and-hold circuit is reused for different pixels at different times, allowing each pixel to benefit from signal holding capability without requiring dedicated sample-and-hold circuits for each pixel, thus reducing overall device area
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 enables efficient power management and noise reduction by adding pixel signals as currents, enhancing image quality and reducing power consumption.
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.