Time of Flight Camera Depth Measurement Using Dynamic Frequency Modulation
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Solution Overview
Problem
Time of flight (TOF) camera devices face limitations in accurately measuring depth beyond a predetermined range due to fixed modulation frequencies, leading to inaccurate distance calculations when objects are farther away.
Innovation Solution
The TOF camera device employs a pulse generator to modulate a pulse signal, using a single frequency for both photo gate signals, with the first photo gate signal having a higher frequency than the second, allowing for increased measurable depth by combining depth information from both frames, even when images are overlapped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed modulation frequency is used in the TOF camera device, then the device structure is simple and operation is easy, but the measurement precision deteriorates when the object distance exceeds the predetermined depth
Solution Approach 1:
The patent applies dynamics by making the modulation frequency adjustable rather than fixed. The controller dynamically changes the modulation frequency based on the measured depth of the object, allowing the system to adapt to different ranging scenarios and maintain high measurement precision across extended depth ranges.
Solution Approach 2:
The patent changes the modulation frequency parameter to resolve the depth measurement limitation. By varying the modulation frequency, the system extends the measurable depth range while maintaining accuracy, directly addressing the contradiction between fixed-frequency simplicity and variable-frequency precision.
2Length of stationary object
If a fixed modulation frequency is used, then the device operation is simple, but the measurable depth range is limited
Solution Approach 1:
The system dynamically adjusts the modulation frequency based on the object's depth, enabling extension of the measurable depth range. The controller automatically manages the frequency switching, maintaining ease of operation while expanding the operational depth range.
Solution Approach 2:
The TOF camera device achieves multi-functionality by being capable of measuring both near and far objects with high precision through variable modulation frequency. This allows a single device to handle diverse ranging scenarios that would otherwise require multiple fixed-frequency systems.
3Measurement precision
If the modulation frequency is increased to improve depth measurement accuracy, then the measurable depth range increases, but the device complexity increases
Solution Approach 1:
The patent implements dynamic frequency selection where the controller adjusts the modulation frequency based on the object's depth. This dynamic approach allows the system to use higher frequencies for nearby objects (improving accuracy) and lower frequencies for distant objects (extending range), managing complexity through intelligent control rather than hardware complexity.
Solution Approach 2:
The system uses periodic modulation of the light source at different frequencies to measure depth at different ranges. By employing periodic actions at multiple frequencies sequentially, the system extends the measurable depth range while maintaining measurement precision through phase comparison techniques.
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 enables accurate depth measurement beyond the previously limited range, enhancing the camera's ability to recognize gestures and objects at greater distances by increasing the measurable maximum depth.
Implementation Method 1
a light source that is configured to emit light in synchronization with the pulse signal to irradiate an object with the light
Implementation Method 2
A time of flight (TOF) camera device detects an object using a phase delay, etc. generated while light modulated into a predetermined frequency is reflected and returned from the object
Data Source
AI summary
A time of flight (TOF) camera device and a method of driving the same are provided. The TOF camera device includes a pulse generator configured to generate a pulse signal, and generate a first photo gate signal and a second photo gate signal; a light source configured to irradiate an object with light emitted in synchronization with the pulse signal; and an image sensor configured to receive light reflected from the object in synchronization with the first photo gate signal during a first frame, and receive light reflected from the object in synchronization with the second photo gate signal during a second frame. The pulse generator is further configured to modulate the pulse signal so as to use a frequency of the light as a single frequency.