TOF Sensor Distance Correction via Multi-Period Depth Subtraction
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Solution Overview
Problem
Time of flight (TOF) sensors face challenges in accurately measuring distances beyond one period of an emitted light signal due to high costs associated with direct TOF methods and inaccuracies in indirect TOF methods for long-distance measurements.
Innovation Solution
An electronic apparatus that uses a light emitter and receiver to acquire phase shift information, allowing for the subtraction of depth values from different time periods to correct distance measurements, and includes a lens unit to adjust emission range and prevent lens flare, enabling accurate long-distance measurements without increasing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct TOF method is used for high-speed measurement, then measurement speed is improved, but unit cost increases due to expensive TDC element
Solution Approach 1:
The patent replaces the expensive, complex TDC element with a simpler, more cost-effective timing mechanism that uses readily available components. The system achieves high-speed measurement capability through a different architectural approach that doesn't rely on costly specialized hardware, thereby reducing unit cost while maintaining measurement speed.
2Ease of manufacture
If indirect TOF method is used to measure phase difference, then cost is reduced, but measurement accuracy deteriorates for objects beyond one period distance
Solution Approach 1:
The patent segments the measurement process into multiple time periods, capturing depth images at different phases. By dividing the measurement into discrete time segments and combining the results, the system extends the measurable distance range beyond a single light period while maintaining the cost benefits of the indirect TOF method.
Solution Approach 2:
The system uses feedback from multiple depth image acquisitions at different time periods to correct and refine distance measurements. By iteratively processing depth images captured across multiple periods and using the accumulated phase information, the system achieves accurate long-distance measurements while maintaining cost-effectiveness.
3Length of stationary object
If multiple depth images are acquired at different time periods and subtracted, then long-distance measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent employs periodic acquisition of depth images at different time periods, using the natural periodicity of the light modulation signal. This periodic approach simplifies the processing by allowing systematic subtraction and comparison of depth images captured at known phase intervals, thereby extending measurable distance while managing complexity through regular, predictable measurement cycles.
4Length of stationary object
If light emission range is increased to improve long-distance measurement, then measurement range is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic adjustment of the lens unit to optimize the emission range based on measurement requirements. By dynamically changing the lens configuration rather than maintaining a fixed wide emission range, the system achieves the necessary measurement range only when needed, thereby reducing overall power consumption while maintaining the capability for long-distance measurements.
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 accurate distance measurement of objects at long distances while reducing costs and power consumption, improving the reliability of depth images by correcting for errors and adjusting emission range.
Implementation Method 1
capable of measuring a distance of an object existing at a long distance by using a phase shift of light
Implementation Method 2
A time of flight (TOF) sensor acquires distance information of an object based on flight time or phase information of light of an emitted towards the object
Implementation Method 3
a lens unit provided on an emission path of the emitted light, the lens unit being configured to adjust an emission range of the emitted light
Implementation Method 4
a non-reflective coating member configured to prevent at least a portion of the reflected light acquired by the light receiver from being reflected by the lens unit to reach the light receiver again
Data Source
AI summary
An electronic apparatus is provided. The electronic apparatus according to the disclosure includes: a light emitter; a light receiver; a memory; and a processor, wherein the processor is configured to: acquire a first depth image based on first reflected light acquired during a first time period and store the first depth image in the memory, acquire a second depth image based on second reflected light acquired during a second time period following the first time period, and acquire distance information between the electronic apparatus and the object included in the second depth image by subtracting a first depth value of each pixel of the first depth image from a second depth value of each pixel of the second depth image, and correct the distance information by using a compensation value acquired based corresponding to time information on the second time period.