Pulsed-Light Distance Measurement With Synchronized Subframes
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Solution Overview
Problem
Existing distance measurement devices using a subframe-based system face errors in measurement results due to differences in detection timing and signal levels between charge accumulation regions across subframes, particularly when performing phase calculations.
Innovation Solution
A distance measurement device that performs charge accumulation and signal detection across multiple subframes with synchronized timing, identifies the subframe corresponding to the pulsed light signal, and calculates distance using phase calculations based on synchronized detection signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of frames for charge accumulation processing is increased for subframes corresponding to farther distance measurement ranges, then the accumulated charge amount is increased, but differences in detection timing and detection signal level occur between charge accumulation regions across subframes, resulting in measurement errors
Solution Approach 1:
The patent applies preliminary action by determining and storing the number of frames for charge accumulation processing for each charge accumulation region before actual distance measurement. This pre-determined frame count is based on the specific detection timing and signal level requirements of each region, allowing the system to accumulate appropriate charge amounts while maintaining consistent detection parameters across all regions, thereby preventing measurement errors.
2Productivity
If phase calculation is performed between charge accumulation regions across subframes with different detection timings, then distance measurement is achieved, but measurement errors occur due to differences in detection timing and signal levels
Solution Approach 1:
The patent applies local quality by assigning different detection timing and signal level parameters to each charge accumulation region based on its specific characteristics. Each region is optimized locally with appropriate frame counts and detection parameters, allowing phase calculation to be performed accurately across regions without suffering from uniform parameter constraints. This localized optimization eliminates measurement errors while maintaining overall distance measurement capability.
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 measurement errors by ensuring consistent detection timing and signal levels across subframes, maintaining accurate distance measurements even in varied distance ranges.
Implementation Method 1
a photoelectric conversion region in which light that is the pulsed light reflected from the measurement target, is converted into charge
Implementation Method 2
a distance image measurement device capable of generating an image signal with improved distance resolution for objects in various distance measurement ranges, by using a sensor device that generates an image signal including distance information based on the time of flight (TOF) of light
Data Source
AI summary
A distance measurement device includes: a light source configured to irradiate a measurement target with pulsed light; a pixel circuit that includes a photoelectric conversion region in which light that is the pulsed light reflected from the measurement target, is converted into charge and a plurality of charge accumulation regions in which the charge converted in the photoelectric conversion region is accumulated; a signal detection unit configured to read, as a plurality of detection signals, signals corresponding to amounts of the charge accumulated in the plurality of respective charge accumulation regions; and a processor configured to control the light source, the pixel circuit, and the signal detection unit and calculate a distance using the plurality of detection signals. The processor is configured to: perform measurement in which the light source generates the pulsed light and charge accumulation processing is executed for a plurality of subframes each being a unit for performing the charge accumulation processing for sequentially accumulating charge in the plurality of charge accumulation regions within a set duration, and the signal detection unit acquires amounts of the charges accumulated in the plurality of charge accumulation regions as the plurality of detection signals for the pulsed light; execute identification processing of identifying a subframe in which a signal, of the plurality of detection signals, corresponding to the pulsed light is generated; and calculate a distance to the measurement target using a result of the identification processing and a phase of the signal, of the plurality of detection signals, corresponding to the pulsed light.