Optical Ranging Apparatus Using Segmented Pixel Groups
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Solution Overview
Problem
Existing ranging apparatuses based on optical Time Of Flight (TOF) technology are susceptible to noise and require complex drive circuits, making them burdensome for CPUs and difficult to operate effectively, especially when dealing with noise spikes and varying exposure periods.
Innovation Solution
A ranging apparatus and method that emit intensity-modulated lights with different time lengths, using a simple light-detecting unit and calculating unit to calculate distances based on phase differences, with exposure periods established in a single pattern and controlled by a reference time changer, reducing noise susceptibility and CPU burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple patterns of exposure periods are used to measure distance, then measurement precision is improved, but device complexity increases due to complex drive circuits
Solution Approach 1:
The patent divides the light-detecting surface into multiple pixel groups, where each group is independently controlled by a simple gate signal. This segmentation allows different pixel groups to capture light during different time periods within a single frame, effectively implementing multiple exposure patterns without requiring complex drive circuits. Each pixel group operates independently with simple timing control, resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If multiple patterns of exposure periods are used to measure distance, then measurement precision is improved, but ease of operation deteriorates due to CPU burden
Solution Approach 1:
The patent segments the frame period into multiple sub-periods, with each pixel group capturing data during its assigned sub-period. This temporal segmentation eliminates the need for complex multi-frame sequences, allowing the CPU to process data from all pixel groups within a single frame. The simplified timing control and single-frame operation significantly reduce CPU burden while maintaining the ability to perform multiple virtual exposure measurements.
3Measurement precision
If exposure periods are extended to capture more light, then measurement precision is improved, but noise susceptibility increases due to noise spikes
Solution Approach 1:
The patent implements periodic action by dividing the frame period into multiple sequential sub-periods, with each pixel group capturing light during its designated sub-period. This periodic temporal division allows the system to achieve the effect of multiple exposure measurements without extending the total exposure time for each pixel group. By concentrating measurements into short, periodic intervals distributed across the frame, the system reduces susceptibility to temporal noise spikes while maintaining measurement precision.
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
The solution reduces noise interference and simplifies the circuitry, allowing for accurate and stable distance measurement without the need for complex calibration, as exposure periods can be adjusted based on external control signals without changing start times, thus reducing processing time and CPU load.
Implementation Method 1
an image capturing device 204 for detecting reflected light from an object 202 irradiated with the modulated light from the light source 200
Data Source
AI summary
A first ranging apparatus includes a light-emitting unit for emitting a series of first through fourth modulated lights which have respective different time lengths from a reference time to respective time points at which the first through fourth modulated lights start being emitted, a light-detecting unit for detecting reflected lights from an object that is irradiated with the first through fourth modulated lights, and a calculating unit for calculating the distance up to the object based on the phase difference between the first through fourth modulated lights and the reflected lights. The light-emitting unit comprises a start time controller for controlling the time lengths. The light-detecting units samples the amounts of the reflected lights in exposure periods established at a constant cycle length from the reference time.