ToF Camera Depth Accuracy via VCSEL Current Control
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Solution Overview
Problem
Existing camera devices using Time of Flight (ToF) methods for acquiring depth maps face challenges in accuracy due to varying reflectivity of light based on surface materials, and they lack the ability to selectively extract depth maps from specific regions within the field of view without additional hardware.
Innovation Solution
A camera device with a light output unit, a light receiving unit, and a control unit that adjusts the current applied to the light source based on object information such as surface material, area, and shape, using a VCSEL light source and polarization members to generate depth maps with improved accuracy and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed current is applied to the light source in ToF depth mapping, then the device structure remains simple, but the depth map accuracy decreases due to varying reflectivity of different surface materials
Solution Approach 1:
The patent applies dynamics by making the light source current adjustable rather than fixed. The control unit dynamically changes the current applied to the light source based on the reflectivity characteristics of different surface materials, enabling adaptation to varying measurement conditions without adding complex hardware structures.
Solution Approach 2:
The patent changes the electrical parameter (current) of the light source to optimize depth map accuracy. By adjusting the current magnitude according to the reflectivity of surface materials, the system compensates for varying light reflection characteristics, thereby improving measurement precision without requiring additional driving devices.
2Measurement precision
If additional driving devices are added to control light source current for different regions, then depth map accuracy for specific regions improves, but the device complexity and cost increase
Solution Approach 1:
The control unit is designed to perform multiple functions: it not only controls the timing and intensity of light source activation but also adjusts the current based on object information and desired measurement regions. This multi-functionality eliminates the need for separate driving devices for each region, reducing overall device complexity while maintaining high measurement precision.
Solution Approach 2:
The patent applies local quality by enabling the control unit to selectively adjust the light source current for specific regions within the field of view. Based on object information such as shape and position, the system optimizes the current applied to illuminate and measure particular areas, thereby achieving high-depth map accuracy for specific regions without requiring dedicated driving devices for each area.
3Measurement precision
If the light source current is increased to improve signal strength for low-reflectivity materials, then the depth map accuracy for those materials improves, but the energy consumption and potential damage to the light source increase
Solution Approach 1:
The patent dynamically changes the current parameter applied to the light source based on the reflectivity characteristics of the measured material. For low-reflectivity materials, the current is increased to enhance the reflected signal strength and improve depth map accuracy. For high-reflectivity materials, the current is reduced to minimize energy consumption and prevent potential damage to the light source, thereby optimizing the balance between measurement precision and energy efficiency.
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 camera device achieves high-accuracy depth map extraction, particularly for specific regions, by controlling the light source current and polarization, enhancing the precision of depth mapping across different surface materials and shapes without requiring additional driving devices.
Implementation Method 1
the light source may include a vertical cavity surface emitting laser (VCSEL)
Implementation Method 2
The light receiving unit may include a polarization member which selectively transmits an input light signal having a predetermined polarization angle of the input light signal
Implementation Method 3
a light receiving unit which receives an input light signal which is reflected from the object
Implementation Method 4
According to the ToF method, a flying time, that is, a time in which light is emitted, reflected, and returned is measured to calculate a distance to an object
Data Source
AI summary
A camera device according to an embodiment of the present invention includes a light output unit which generates an output light signal and emits the output light signal to an object, a light receiving unit which receives an input light signal which is reflected from the object and then input to the light receiving unit, a depth information generation unit which generates a depth map of the object using the input light signal input to the light receiving unit, and a control unit which controls the light output unit, the light receiving unit, and the depth information generation unit, wherein the light output unit includes a light source for generating the output light signal, and the control unit controls a current applied to the light source on the basis of information about the object.