Imaging Device Duty Ratio Harmonic Noise Reduction
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Solution Overview
Problem
Existing imaging devices face challenges in accurately generating depth images due to harmonic distortion caused by integer multiple duty ratios between light control signals and photo control signals, leading to reduced accuracy and performance.
Innovation Solution
The imaging device employs a logic circuit to generate raw data for depth images by using a light control signal with a non-integer multiple duty ratio, and a delay circuit to adjust the light control signal's delay time, optimizing the duty ratio to minimize harmonic noise and improve depth data accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an integer multiple duty ratio is used between light control signal and photo control signal, then device complexity is reduced, but measurement precision of depth images deteriorates due to harmonic distortion
Solution Approach 1:
The patent changes the duty ratio parameter from an integer multiple relationship to a non-integer multiple relationship between the light control signal and photo control signal. Specifically, it sets the duty ratio of the light control signal to 50% and the photo control signal to 25%, creating a non-integer multiple (2:1) relationship that eliminates harmonic distortion while maintaining simple control logic.
2Measurement precision
If duty ratio is optimized to minimize harmonic noise, then measurement precision of depth images is improved, but device complexity increases due to additional delay circuit and calibration
Solution Approach 1:
The patent introduces a delay circuit as an intermediary component between the logic circuit and the light source driver. This delay circuit adjusts the timing of the light control signal to achieve the optimal non-integer multiple duty ratio relationship, thereby reducing harmonic distortion without requiring complex control logic in the main processing unit.
3Measurement precision
If non-integer multiple duty ratio is used, then measurement precision of depth images is improved by reducing harmonic distortion, but ease of operation deteriorates due to additional calibration steps
Solution Approach 1:
The patent implements a self-calibration mechanism where the logic circuit automatically determines the optimal duty ratio relationship between light control and photo control signals. The system performs internal calibration by adjusting the delay time of the light control signal to minimize harmonic distortion, eliminating the need for manual calibration by the user.
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 reduces harmonic noise and enhances the accuracy of depth images by selecting a duty ratio that minimizes the difference between computed and actual depths, improving the overall performance of the imaging device.
Implementation Method 1
a photodiode configured to generate an electrical charge in response to light output by the light source and reflected from a subject
Data Source
AI summary
An imaging device includes a light source configured to operate by a light control signal having a first duty ratio; a pixel array in which a plurality of pixels are disposed, each of the plurality of pixels including a photodiode for generating electrical charges in response to a light reception signal output by the light source and reflected from a subject, and a pixel circuit for outputting a pixel signal corresponding to electrical charges of the photodiode; and a logic circuit configured to generate raw data for generating a depth image using the pixel signal, wherein the logic circuit inputs a photo control signal having a second duty ratio to the pixel circuit connected to the photodiode in each of the plurality of pixels, and wherein the first duty ratio is not an integer multiple of the second duty ratio.