TOF Sensor Sampling Ratio Control for High Dynamic Range Depth Sensing
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Solution Overview
Problem
Existing time-of-flight (TOF) based distance measuring techniques face challenges in balancing signal levels for near and far distances, leading to overexposure at close ranges and insufficient signal levels at long ranges in high dynamic range applications.
Innovation Solution
A method and system that adjust the ratio of signal samples taken at different distances by considering both depth and luminance information, using a TOF sensor to perform first and second signal samplings with different time differences for near and far ranges, respectively, and dynamically adjust the proportions based on obtained depth and luminance data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single signal sampling method is used for all distances, then the measurement mechanism remains simple, but overexposure occurs at close distances and insufficient signal level occurs at long distances
Solution Approach 1:
The patent divides the signal sampling process into multiple segments: first signal sampling for near distances and second signal sampling for far distances. Each sampling segment uses different time differences optimized for its specific distance range, allowing the system to maintain simple measurement mechanisms for each segment while achieving balanced signal levels across all distances.
Solution Approach 2:
The patent dynamically adjusts the first proportion and second proportion based on obtained depth information and luminance information. This dynamic adjustment allows the system to adaptively balance signal levels for near and far distances, resolving the contradiction between measurement simplicity and signal level balance.
2Ease of operation
If the first time difference is used for all signal samplings, then the sampling process is simple, but far distance signals become insufficient
Solution Approach 1:
The patent applies different time differences to different signal sampling processes: the first time difference is optimized for near distance signals while the second time difference is optimized for far distance signals. This local quality approach ensures that each sampling process has the appropriate time difference for its specific distance range, maintaining sampling simplicity while ensuring sufficient signal levels for all distances.
3Quantity of substance
If the second time difference is used for all signal samplings, then far distance signals are sufficient, but near distance signals become overexposed
Solution Approach 1:
The patent changes the time difference parameter based on the distance range being measured. By using the first time difference for near distances and the second time difference for far distances, the system optimizes signal levels for each range. The dynamic adjustment of first proportion and second proportion based on depth and luminance information further refines this parameter change to prevent overexposure and underexposure.
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 improves the effectiveness of high dynamic range sampling by balancing signal levels across varying distances, preventing overexposure or underexposure by optimizing the sampling proportions based on actual scene conditions.
Implementation Method 1
In the time-of-flight (TOF) based distance measuring techniques, pulse modulation measures the distance of the target by the time difference between the transmission and reception of light pulses
Implementation Method 2
a TOF sensor, including a pixel array having a plurality of pixels, wherein the TOF sensor is under the control of the control circuit and configured to control each pixel of a plurality of pixels to perform a first signal sampling
Data Source
AI summary
A time-of-flight distance measuring method and TOF distance measuring system. The distance measuring method includes: intermittently transmitting a plurality of pulses from a pulse generation unit; controlling a TOF sensor to allow each pixel of a plurality of pixels in the TOF sensor to continuously perform a first signal sampling first proportion for a first predetermined time on a first proportion of a plurality of reflected signals and performs a second signal sampling second proportion for a second predetermined time on a second proportion of a plurality of reflected signals, so as to generate a plurality of sampling results corresponding to the plurality of pixels; obtaining a plurality of depth information and a plurality of luminance information corresponding to the plurality of pixels according to the plurality of sampling results; and adjusting the first proportion and the second proportion according to the plurality of depth information and the plurality of luminance information.