Time-of-Flight Camera Dual Mode Sensor
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Solution Overview
Problem
Time-of-flight cameras face limitations in power efficiency and operational flexibility for monitoring tasks, particularly in detecting motion without requiring additional image analysis or high-power illumination.
Innovation Solution
A time-of-flight camera system that operates in both 3D mode and power saving mode, using a single sensor with two integration nodes to determine distance and detect motion based on differential values, allowing for reduced power consumption and motion detection using ambient light without additional illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the time-of-flight camera operates in 3D mode with modulation signal for distance determination, then accurate distance measurement is achieved, but power consumption increases
Solution Approach 1:
The system dynamically switches between two operational modes: 3D mode for accurate distance measurement and power saving mode for motion detection. The camera adapts its operating parameters (modulation frequency, illumination intensity) based on the detection task requirements, using higher power only when 3D distance measurement is needed and lower power when motion detection suffices
Solution Approach 2:
The system changes key operating parameters including modulation frequency and illumination intensity based on the operational mode. In power saving mode, the modulation frequency is reduced and illumination intensity is lowered compared to 3D mode, enabling motion detection with reduced power consumption while maintaining the ability to switch to full 3D mode when required
2Measurement precision
If the time-of-flight camera uses additional illumination and image analysis for motion detection, then motion detection accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The system extracts motion detection capability from the full 3D imaging function by using only the differential signal between integration nodes A and B. This allows motion detection without requiring complete image analysis, additional illumination sources, or complex processing algorithms, thereby reducing device complexity while maintaining detection accuracy
Solution Approach 2:
The existing integration nodes A and B, designed for distance measurement, are also utilized for motion detection by computing their differential values. This multi-functionality eliminates the need for separate motion detection hardware or additional illumination systems, reducing overall device complexity while enabling accurate motion detection
3Measurement precision
If the time-of-flight camera operates at high frequency for detailed detection, then detection precision is improved, but power consumption increases
Solution Approach 1:
The system employs periodic action by switching between high-frequency 3D mode operation and low-frequency power saving mode based on detection needs. The camera operates at high frequency only when 3D distance measurement is required, and switches to low-frequency operation for motion detection tasks, thereby reducing overall power consumption while maintaining detection precision when needed
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
Enables efficient power management and flexible operation, allowing for motion detection without additional image analysis and reduced power usage, with the ability to switch to 3D mode upon detecting motion, while maintaining accurate distance measurement capabilities.
Implementation Method 1
the time-of-flight sensor is preferably operated independently from the illumination means by means of a control signal for motion detection... an object motion is determined based on a differential value at the integration nodes
Implementation Method 2
Time-of-flight cameras in particular refer to time-of-flight camera systems or TOF-camera systems which derive time-of-flight information from a phase shift of emitted and received radiation
Implementation Method 3
PMD-cameras comprising photo mixing detectors (PMDs)
Data Source
AI summary
A method for operating a time-of-flight camera including a time-of-flight sensor comprising an array of time-of-flight pixels with at least two integration nodes, wherein in a 3D mode the time-of-flight sensor and an illumination means are operated by means of a modulation signal and on the basis of the charges accumulated at the integration nodes distance values are determined, characterized in that in a power saving mode the time-of-flight sensor is operated with a control signal for motion detection, the frequency of which is lower than a lowest frequency of the modulation signal for a distance determination in the 3D mode, wherein an object motion is determined based on a differential value at the integration nodes is provided.