CMOS Image Sensor Motion Sensing Using Dual Integration Times

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Solution Overview

Problem

CMOS image sensors face a trade-off between reducing power consumption and maintaining performance, with existing methods not effectively optimizing both factors for motion sensing in mobile devices.

Innovation Solution

The implementation of a method using a pair of pixels with distinct integration times and a readout circuit to generate comparison signals, allowing for efficient motion sensing by comparing signals from each pixel, thereby optimizing power usage while maintaining performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the integration time is increased to improve motion sensing accuracy, then the measurement precision is improved, but the power consumption increases

Engineering Contradiction:

Improvemotion sensing accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The pixel array is divided into multiple pixel groups, where each group contains pixels with different integration times (first integration time and second integration time). This segmentation allows simultaneous capture of moving and stationary objects with different exposure durations, enabling motion detection through comparison while managing power consumption by not requiring all pixels to operate at maximum integration time continuously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The image sensor alternates between different integration time periods in a periodic manner. During certain frame periods, pixels use the first integration time, while during other frame periods, they use the second integration time. This periodic switching enables the system to achieve motion sensing capabilities without continuously operating at high power consumption levels, as the longer integration time is applied only periodically to specific pixel groups.

Inventive Principle:

Principle #19Periodic action

2Use of energy by moving object

If the integration time is decreased to reduce power consumption, then the power consumption is reduced, but the measurement precision deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidmotion sensing accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The integration time parameter is changed across different pixel groups and time periods. By varying the integration time parameter (using first integration time for some pixels and second integration time for others), the system optimizes the balance between power consumption and motion sensing accuracy. The readout circuit compares signals from pixels with different integration time parameters to detect motion, ensuring that power consumption is reduced without sacrificing measurement precision.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If multiple pixels with different integration times are used to sense motion, then the motion sensing capability is improved, but the device complexity increases

Engineering Contradiction:

Improvemotion sensing capabilityVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The image sensor is designed to perform multiple functions using the same pixel array and readout circuit. The system can operate in different modes (capturing moving objects, stationary objects, or both simultaneously) by controlling the integration times of different pixel groups. This multi-functionality reduces the need for separate dedicated sensors for different purposes, thereby managing device complexity while improving motion sensing capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The pixel array is pre-configured with multiple pixel groups that have different integration time characteristics. The readout circuit is pre-designed to compare signals from these pixel groups and generate comparison signals indicating motion. This preliminary configuration enables motion sensing to be performed automatically without requiring complex real-time processing or additional hardware, thus improving motion sensing capability while keeping device complexity manageable.

Inventive Principle:

Principle #10Preliminary action

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 effective motion sensing with reduced power consumption, enhancing the operational characteristics of CMOS image sensors in mobile devices.

Implementation Method 1

generating a first pixel signal by using the first pixel during a first integration time of a frame period, generating a second pixel signal by using the second pixel during a second integration time of the frame period

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS9204143B2Image sensor, operation method thereof, and system including the same

Publication Date: 2015.12.01 SAMSUNG ELECTRONICS CO LTD

AI summary

A motion sensing method is implemented by an image sensor, the image sensor including a first pixel and a second pixel. The method includes outputting a first pixel signal of the first pixel during a first integration time of a frame period, outputting a second pixel signal of the second pixel during a second integration time of the frame period, and generating comparison signals indicative of a sensed moving object by comparing the first pixel signal and the second pixel signal.