ToF Light Reception Timing Shift for Interference Filtering
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Solution Overview
Problem
Existing time-of-flight (ToF) methods for distance measurement are prone to erroneous calculations due to interference from other light sources, leading to increased processing load and power consumption when random offsets are used to differentiate between reflected and interference light.
Innovation Solution
A light receiving device and method that introduces a shift period in the light emission timing, altering the ratio of shift periods within medium periods to disrupt periodicity and enable accurate distance calculation by distinguishing reflected light from interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If random offset is inserted every time pulsed light is emitted to differentiate reflected light from interference light, then measurement precision is improved, but processing load and power consumption increase
Solution Approach 1:
The patent applies periodic action by inserting offsets at regular intervals (every N times of pulsed light emission) rather than every single emission. This periodic approach maintains the ability to differentiate interference light while significantly reducing the processing load and power consumption compared to continuous random offset insertion.
Solution Approach 2:
The patent uses preliminary action by pre-setting fixed offset values in advance rather than generating random offsets in real-time for each emission. This allows the system to prepare offset patterns beforehand, reducing the computational burden during actual distance measurement operations.
2Measurement precision
If random offset is inserted every time pulsed light is emitted to differentiate reflected light from interference light, then measurement precision is improved, but device complexity increases
Solution Approach 1:
By making the offset insertion periodic rather than continuous, the patent simplifies the circuit design and control logic. The system only needs to implement offset insertion at specific intervals, reducing the complexity of timing control and signal processing circuits.
Solution Approach 2:
The patent changes the parameter of offset insertion frequency from every emission to every Nth emission. This parameter change simplifies the overall system complexity while maintaining the core functionality of interference light differentiation through fixed offset values.
3Reliability
If offset is inserted frequently to prevent erroneous distance measurement from interference light, then reliability is improved, but loss of time increases due to processing overhead
Solution Approach 1:
The periodic offset insertion strategy ensures that interference light can still be detected and filtered out reliably, as interference patterns will be captured at regular intervals. This maintains measurement reliability while minimizing the time lost to offset processing compared to continuous insertion.
Solution Approach 2:
The patent applies partial action by inserting offsets only at necessary intervals rather than continuously. This partial approach is sufficient to identify and eliminate interference light effects while reducing the overall processing time and computational overhead.
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 reduces processing load and power consumption while effectively filtering out interference, ensuring accurate distance measurements by identifying and excluding false data from other light sources.
Implementation Method 1
In the distance measurement by a time of flight (ToF) method, pulse-like light (pulsed light) is emitted to a subject to be measured at a predetermined cycle, and reflected light from the subject is detected, thereby measuring a round-trip time of light and calculating a distance to the subject.
Implementation Method 2
a light receiving unit that receives reflected light in which light emitted from a light emitting unit according to a light emission instruction issued on the basis of a predetermined processing cycle is reflected by a subject
Data Source
AI summary
A light receiving device according to the present technology includes: a light receiving unit that receives reflected light in which light emitted from a light emitting unit according to a light emission instruction issued on the basis of a predetermined processing cycle is reflected by a subject; and a calculation unit that calculates information regarding a distance to the subject according to a difference between a light emission timing of the light emitting unit and a light reception timing of the light receiving unit, in which the light emission instruction is issued at a timing delayed by a shift period with respect to a reference timing in each cycle of the predetermined processing cycle for each medium period including a plurality of small periods each including one time of light emission, and a ratio of the shift period to each of the small periods is changed for each large period including a plurality of the medium periods.