Wearable Projector Palm Focus Control via 3D Feedback

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Solution Overview

Problem

Wearable projecting devices experience poor stability in image definition when projecting onto a palm surface due to variations in the relative position between the device and the palm, caused by finger movement.

Innovation Solution

A focusing method that continuously acquires position information of the projection center on the palm, calculates the distance, determines and adjusts the focal length of the lens set, and corrects it in real-time using a 3D camera and processing module, ensuring high stability of image definition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the wearable projecting device is worn on a finger for portability and ease of operation, then the ease of operation is improved, but the stability of image definition deteriorates due to finger movement causing relative position variations

Engineering Contradiction:
ImprovewearabilityVSAvoidstability of image definition
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system continuously detects the position of the projection center on the palm surface and uses this feedback to dynamically adjust the focal length of the lens set, creating a closed-loop control system that maintains image quality despite finger movement

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The focal length of the lens set is made dynamically adjustable rather than fixed, allowing the optical system to adapt in real-time to changing distances between the projector and palm surface

Inventive Principle:
Principle #15Dynamics

2Reliability

If the focal length is adjusted in real-time to maintain image definition, then the stability of image definition is improved, but the device complexity increases due to additional sensors and control mechanisms

Engineering Contradiction:
Improvestability of image definitionVSAvoidcomplexity of focusing system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system uses the projection center detection capability that is already inherent to the wearable projector to also determine distance and control focusing, making the system self-sufficient without requiring separate complex measurement devices

Inventive Principle:
Principle #25Self-service

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 method achieves stable and clear image projection on the palm surface by dynamically adjusting the focal length in response to finger movements, maintaining image quality across changing positions.

Implementation Method 1

acquiring, by means of a 3D camera, position information of a projection center, on a palm surface, of the wearable projecting device

Methodology Applied
Scientific Effect3D imaging: Time of Flight

Implementation Method 2

determining a focal length of a lens set in the wearable projecting device; adjusting the focal length of the lens set

Methodology Applied
Scientific EffectLight refraction: Refraction

Data Source

PatentEP3139600B1Projection method
Publication Date: 2020.09.30 BOE TECHNOLOGY GROUP CO LTD
  • EP3139600B1 patent drawingFigure 1
  • EP3139600B1 patent drawingFigure 2
  • EP3139600B1 patent drawingFigure 3~4

AI summary

A wearable projecting device, a focusing method and a projection method thereof are disclosed. The focusing method includes: acquiring position information of a projection center of the wearable projecting device on a palm; determining a distance between the projection center and the wearable projecting device according to the acquired position information of the projection center of the wearable projecting device on the palm at a set frequency; determining a focal length of a lens set in the wearable projecting device according to the determined distance between the projection center and the wearable projecting device; and adjusting the lens set according to the determined focal length of the lens set. This focusing method improves stability of definition in display of images projected on the palm surface by the wearable projecting device.