Optical Scanner Amplifier for Thin Retinal Display Cable

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Solution Overview

Problem

Existing optical scanning head-mounted displays and retinal scanning head-mounted displays often compromise on wearability and usability due to the size, weight, and thickness of the transmission cable connecting the head mount unit and the optical scanning controller.

Innovation Solution

Incorporating an amplifier in the head mount unit to amplify motion signals from the optical scanner and a difference generator with a filter in the optical scanning controller to stabilize and clean the signals, reducing the number of signal lines needed in the transmission cable, thereby minimizing noise and enhancing the flexibility and lightness of the cable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the transmission cable is made thicker to accommodate more signal lines, then signal transmission capability is improved, but the weight and thickness of the head mount unit increase

Engineering Contradiction:
Improvesignal transmission capabilityVSAvoidweight of head mount unit
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent extracts the signal processing functions (amplification, difference generation, filtering) from the optical scanning controller and relocates them to the head mount unit. This allows the transmission cable to carry only essential signals, reducing the number of required signal lines from multiple lines to just two lines, thereby reducing cable thickness and head mount unit weight while maintaining signal transmission capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the signal transmission parameters by implementing signal processing at the head mount unit end, which transforms the signal transmission requirements. Instead of transmitting multiple processed signals through thick cables, the system transmits raw sensor signals through thin cables and performs processing locally, changing the fundamental approach to signal transmission

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the transmission cable is made thinner to improve flexibility and wearability, then wearability is improved, but the number of signal lines must be reduced which may affect signal quality

Engineering Contradiction:
ImprovewearabilityVSAvoidsignal transmission quality
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies preliminary signal processing (amplification and filtering) at the head mount unit before transmission through the cable. By preprocessing the motion signals to amplify them and remove noise before they enter the transmission cable, the system ensures high signal quality is maintained even when using a thin cable with limited signal lines

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where motion signals from the optical scanner are processed, and the processed signals are used to control the optical scanning controller, which in turn controls the laser beam scanning. This closed-loop feedback system ensures that even with reduced cable capacity, the signal transmission quality remains high through continuous monitoring and adjustment

Inventive Principle:
Principle #23Feedback

3Device complexity

If more signal lines are included in the transmission cable, then signal processing capability is improved, but the cable weight and head mount unit size increase

Engineering Contradiction:
Improvesignal processing capabilityVSAvoidsize of head mount unit
Core Design Contradiction:
Device complexityVSVolume of moving object

Solution Approach 1:

The patent segments the signal processing functions into two locations: simple signal transmission through the cable and complex signal processing (amplification, difference generation, filtering) in the optical scanning controller. This segmentation allows the head mount unit to remain compact while maintaining advanced signal processing capability through strategic placement of processing components

Inventive Principle:
Principle #1Segmentation

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 configuration enhances the wearability and usability of the head mount unit by reducing its size and weight, improving the transmission cable's flexibility and reducing noise, while maintaining effective signal transmission and image projection quality.

Implementation Method 1

the head mount unit (HM) includes an amplifier (43) that amplifies a motion signal corresponding to a tilt of the mirror (31)

Methodology Applied
Scientific EffectSignal amplification:

Implementation Method 2

a filter (127) that removes noise from the difference signal generated by the difference generator (126)

Methodology Applied
Scientific EffectNoise filtering: Filter (electronic)

Data Source

PatentEP3318916B1Optical scanning head-mounted display and retinal scanning head-mounted display
Publication Date: 2019.09.04 MITSUMI ELECTRIC CO LTD
  • EP3318916B1 patent drawingFigure 1
  • EP3318916B1 patent drawingFigure 2
  • EP3318916B1 patent drawingFigure 3~4

AI summary

An optical scanning head-mounted display includes an optical scanning controller that emits, as image light, a laser beam in accordance with an image signal; a transmission cable that transmits the image light emitted from the optical scanning controller; and a head mount unit provided with an optical scanner including a mirror for scanning the image light transmitted by the transmission cable, wherein the head mount unit includes an amplifier that amplifies a motion signal corresponding to a tilt of the mirror, the motion signal being output from the optical scanner, and wherein the optical scanning controller includes a difference generator that generates a difference signal from the motion signal output from the amplifier through the transmission cable and a filter that removes noise from the difference signal generated by the difference generator.