CMOS Image Sensor Pixel Block Reset Control

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Solution Overview

Problem

Conventional CMOS image sensors face a trade-off between image lag and dark current, and the use of voltage pumps to reduce image lag increases cost and power consumption while introducing noise.

Innovation Solution

The method involves dividing the pixel array into blocks, where one block exposes while another block is reset, eliminating the need for a voltage pump and allowing for longer resetting times, thus reducing image lag and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a voltage pump is used to reduce image lag, then image lag is reduced, but power consumption increases and noise is introduced

Engineering Contradiction:

Improveimage lag reductionVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The pixel array is divided into multiple pixel blocks that can be independently controlled. While one pixel block is performing exposure, another pixel block performs reset operations. This segmentation allows the reset function to be distributed across multiple blocks over time, eliminating the need for a voltage pump while maintaining effective reset timing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The reset operation is performed in advance during the exposure time of other pixel blocks. By utilizing the exposure time of one block to perform reset on another block, the reset action is completed before it is needed for the active block, eliminating the need for accelerated reset mechanisms.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a voltage pump is used to modify image lag, then image lag is modified, but cost and device complexity increase

Engineering Contradiction:

Improveimage lag controlVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The pixel array is divided into multiple pixel blocks with independent control signals. This segmentation allows the reset function to be distributed across multiple blocks over time, eliminating the need for a voltage pump while maintaining effective reset timing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different pixel blocks undergo reset and exposure operations in periodic cycles. While block A exposes, block B resets; while block B exposes, block C resets. This periodic alternation ensures continuous operation without requiring additional circuitry beyond the control logic.

Inventive Principle:

Principle #19Periodic action

3Reliability

If process parameters are changed to reduce image lag, then image lag is reduced, but dark current increases

Engineering Contradiction:

Improveimage lagVSAvoiddark current

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system maintains continuous useful action by having multiple pixel blocks operating in different phases. While one block exposes, another resets, ensuring that the reset function is continuously performed without interrupting the exposure of any block, thereby maintaining image quality without introducing dark current issues.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS7948537B2Method for resetting image sensing and image sensing device using the same

Publication Date: 2011.05.24 NOVATEK MICROELECTRONICS CORP

AI summary

A method for resetting image sensing and an image sensing device using the same are provided. The method for resetting image sensing includes generating a plurality of reset signals and a plurality of control signals, and using the reset signals and the control signals to control a pixel array to reset and expose. The pixel array has a plurality of pixel blocks, each of the pixel blocks has a plurality of pixel sensing units. When the plurality of pixel sensing units of one of the pixel blocks expose to acquire a plurality of sensing signals sequentially, the plurality of pixel sensing units of another one of the pixel blocks are reset.