Image Sensor Average Switch for Power and SNR Trade-off

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Solution Overview

Problem

Conventional image sensors face challenges in reducing power consumption while maintaining signal-to-noise ratio (SNR) in power saving modes, as they either ignore pixel data or fail to effectively lower system power consumption through averaging operations.

Innovation Solution

The image sensor employs an average switch to alternate between normal and low power modes, averaging pixel data between readout lines and turning off parts of the readout circuit, including the use of dummy pixels to reduce power noise and consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If pixel circuits in even columns are turned off to save power, then total power consumption is reduced, but a part of pixel data is ignored

Engineering Contradiction:

Improvetotal power consumptionVSAvoidpixel data

Core Design Contradiction:

Use of energy by moving objectVSLoss of information

Solution Approach 1:

The patent merges data from odd and even column pixel circuits through averaging switches that combine signals from both columns during low power mode, ensuring that data from even columns (which would otherwise be ignored) is integrated into the final output, thus preventing information loss while maintaining power savings

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If averaging operation is performed on pixel data, then signal-to-noise ratio is improved, but system power consumption is not reduced

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidsystem power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic switching between normal mode and low power mode through control logic that selects different operational states of the averaging switches and readout circuits, enabling the system to perform averaging operations only when necessary while reducing power consumption during low power mode by turning off unnecessary circuit components

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies averaging operations selectively to specific columns (odd and even columns) rather than all columns uniformly, with averaging switches configured to operate on particular pixel data streams based on the operational mode, thus optimizing the balance between noise reduction and power consumption

Inventive Principle:

Principle #3Local quality

3Measurement precision

If averaging switches are conducted to average pixel data, then SNR is improved, but power consumption increases

Engineering Contradiction:

ImproveSNRVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent employs periodic switching between normal mode and low power mode, where averaging switches are activated periodically based on operational requirements, allowing the system to achieve noise reduction benefits when needed while minimizing energy consumption during low power mode by deactivating the averaging switches and related readout circuits

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS10609319B2Image sensor capable of averaging pixel data

Publication Date: 2020.03.31 PIXART IMAGING INC

AI summary

An image sensor including a first pixel circuit, a second pixel circuit, a first readout line, a second readout line, a first readout circuit, a second readout circuit and an average switch is provided. The first and second pixel circuits are in two columns of a pixel array. The first readout line transmits pixel data of the first pixel circuit to the first readout circuit. The second readout line transmits pixel data of the second pixel circuit to the second readout circuit. The average switch is arranged between the first and second readout lines and used to electrically connect the first and second readout lines in an average mode to average the pixel data on the first and second readout lines.