ToF Distance Sensing Exposure Control Across Near and Far Ranges
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Solution Overview
Problem
Existing distance measuring devices using the ToF method face limitations in irradiating a wider range of distances with light due to power consumption and laser output intensity constraints, leading to exposure variations only in parts of the measuring range, particularly in short distance sections.
Innovation Solution
A distance measuring device with a control unit that performs exposure control based on the distance between the device and the subject, ensuring a wider range is irradiated with light and maintaining consistent exposure times to achieve a designated confidence value across different viewing distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If automatic exposure control is performed to acquire maximum confidence value within saturation threshold, then high-quality distance image is obtained, but exposure variation occurs only in part of short distance section due to power consumption and laser output intensity limits
Solution Approach 1:
The patent implements dynamic exposure control by switching between two operating modes: first operating mode uses maximum exposure time for distant subjects, while second operating mode uses shorter exposure time for nearby subjects. The control unit dynamically selects the appropriate mode based on detected subject distance, enabling adaptability across the entire distance measuring range while maintaining high-quality distance images throughout.
2Illumination intensity
If laser output intensity is increased to irradiate wider distance range, then more sections are sufficiently illuminated, but power consumption exceeds allowable limit
Solution Approach 1:
The patent applies local quality by providing different exposure conditions for different distance zones. Nearby subjects receive light with maximum exposure time, while distant subjects receive light with extended exposure time up to a maximum value. This spatially differentiated approach ensures sufficient illumination across the entire distance range without requiring uniformly high power consumption throughout.
Solution Approach 2:
The control unit periodically determines subject distance and switches between first and second operating modes based on the detected distance. This periodic assessment and mode switching enables the system to adapt light irradiation to actual distance requirements, maintaining adequate illumination while minimizing overall power consumption by using maximum exposure time only when necessary for distant subjects.
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 allows for effective exposure control over a broader distance range, ensuring high-quality distance images are acquired by maintaining a consistent light amount and confidence value, even in varying distances and lighting conditions.
Implementation Method 1
The ToF method is a method for measuring a distance to a subject (measuring object) by irradiating the subject with light from a light source and detecting a flight time of the light until the irradiation light is reflected by the subject and returns to a light detection unit.
Data Source
AI summary
A distance measuring device of the present disclosure includes: a light source that irradiates a subject with light; a light detection unit that receives reflected light from the subject based on irradiation light from the light source; and a control unit that performs exposure control according to a distance between the distance measuring device and the subject. Furthermore, an electronic device of the present disclosure includes the distance measuring device having the configuration described above.