Surface Imaging in Personal Care Devices Using Pattern-Based 3D Sensing
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Solution Overview
Problem
Existing personal care devices with integrated imaging functions face challenges in accurately determining the orientation and distance of a surface relative to the device, which is crucial for optimal operation, and existing 3D reconstruction methods are not suitable for compact integration and suffer from inaccuracies due to device and surface movement.
Innovation Solution
A personal care device with an on-board illumination system projecting a known pattern, combined with an image sensor, detects the pattern's shape to derive surface orientation and distance, using collimating lenses, depth-focused beams, or axicon lenses to create patterns that change with depth, and employs motion sensors to stabilize device motion for accurate 3D modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If structured light patterns or calibration grids are projected onto the tissue surface to enable 3D reconstruction, then 3D modeling capability is achieved, but the device requires large and/or multiple projector systems or additional laser sources which are not suitable for compact integration into a handheld personal care device
Solution Approach 1:
The patent combines the illumination system and image sensor into a single integrated imaging system within the handheld device. The illumination system projects a known pattern while the image sensor captures the reflected light, merging functions that would traditionally require separate projector and camera systems. This integration enables compact form factor while maintaining 3D reconstruction capability through the use of a single optical axis alignment between illumination and sensing components.
Solution Approach 2:
The patent uses a simplified optical copy approach by projecting a known illumination pattern and analyzing its distortion in the captured image. Instead of requiring complex structured light projectors, the system projects a basic pattern (such as a grid or geometric shape) and derives 3D information from the pattern's deformation, shadow, or perspective distortion in the 2D captured image. This copying approach enables 3D reconstruction with minimal optical components.
2Measurement precision
If 2D images with superposed distorted light patterns are used for 3D reconstruction, then 3D modeling is enabled, but the movement of handheld devices and the object being imaged causes inaccuracy and drift in the reconstruction
Solution Approach 1:
The patent implements feedback mechanisms by continuously capturing images during device movement and using the known illumination pattern as a reference. The system detects the pattern's position, orientation, and distortion in each captured image, then uses this information to calculate and correct for device motion and surface movement. This feedback loop enables real-time compensation for drift and maintains reconstruction accuracy despite handheld device movement.
Solution Approach 2:
The patent projects a known illumination pattern onto the surface before capturing the image, establishing a reference frame in advance. By having the pattern projected and captured simultaneously, the system preemptively captures the geometric relationship between the device and surface at each moment. This preliminary establishment of geometric reference enables subsequent processing to accurately reconstruct 3D shape even during motion, as each captured frame contains self-contained geometric information.
3Measurement precision
If an inertia measurement unit is used to obtain position and orientation of the camera relative to the object being imaged, then 3D image construction from multiple viewpoints is enabled, but the system complexity increases and accuracy is reduced due to device movement
Solution Approach 1:
The patent enables the imaging system to self-determine its position and orientation relative to the surface by analyzing the captured image of the known illumination pattern. Instead of requiring external inertial sensors, the system uses computer vision algorithms to detect the pattern's geometric transformation (scaling, rotation, skew) in the 2D image and inversely calculate the camera's pose. This self-service approach eliminates additional sensors while providing the necessary pose information for 3D reconstruction.
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
Enables precise determination of surface orientation and distance, allowing for improved 3D modeling and feedback, reducing the need for additional sensors and improving the accuracy of 3D reconstruction by stabilizing device motion.
Implementation Method 1
an illumination system in the head for projecting a known illumination pattern onto a surface to be imaged; an image sensor in the head capturing images of the surface to be imaged; detect the illumination pattern in the captured images
Implementation Method 2
The illumination system comprises a light source and a collimating lens. The collimating lens projects a fixed pattern (i.e. fixed size and shape) to all depths. In some examples, the position of the pattern within the field of view of the image sensor may be used to derive depth information.
Data Source
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AI summary
A personal care device comprises an illumination system for projecting a known illumination pattern onto a surface to be imaged and an image sensor for capturing images of the surface to be imaged. The illumination pattern is detected in the captured images and an orientation of the surface to be imaged is derived from a shape of the illumination pattern.