Optical Scanner Phase Control for Image Area Protection

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Solution Overview

Problem

Existing optical scanners face issues with irradiation fields entering the image area, affecting image quality due to changes in resonance frequency caused by temperature variations and deterioration over time, leading to reduced image quality and interference.

Innovation Solution

The implementation of a control unit that adjusts the phase difference and drive frequency of the light deflector to ensure the irradiation fields overlap with detection fields without entering the image area, using a shielding mechanism to prevent interference and maintain image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the optical scanner uses a wide deflection angle to achieve stable operation despite resonance frequency changes, then reliability is improved, but the irradiation field enters the image area causing image quality degradation

Engineering Contradiction:
Improvestable operationVSAvoidimage quality
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The optical scanner is divided into functional zones: an image area for displaying images and a non-image area (including detection fields) for synchronization detection. The scanning beam is segmented in time and space to operate in different zones during different phases of the scanning cycle, preventing irradiation field intrusion into the image area while maintaining stable wide-angle operation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary synchronization detection in the non-image area before the beam enters the image area. By detecting the irradiation field in advance in the detection field region and adjusting timing/phasing accordingly, the system ensures that when the beam transitions to the image area, proper synchronization is already established, preventing image quality degradation

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If the optical scanner operates with resonance frequency changes due to temperature and deterioration, then adaptability is improved, but the irradiation field enters the image area affecting image quality

Engineering Contradiction:
Improvetemperature compensationVSAvoidimage quality
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system uses photodetectors in the detection field to detect the irradiation field and generate feedback signals. This feedback is used to adjust the timing and phasing of the scanning beam, ensuring that even when resonance frequency changes occur due to temperature or deterioration, the beam timing is corrected to prevent intrusion into the image area

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts scanning parameters (timing, phasing, deflection angle) based on detected resonance frequency changes. By monitoring the irradiation field position and modifying operational parameters in real-time, the system adapts to temperature and deterioration effects while maintaining proper beam positioning to avoid image area contamination

Inventive Principle:
Principle #35Parameter changes

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 solution effectively reduces the impact of resonance frequency changes on image quality by ensuring irradiation fields do not enter the image area, thereby maintaining stable and high-quality image projection.

Implementation Method 1

a light deflector 13 that scans the irradiation light 600 emitted from the light-source device 11

Methodology Applied
Scientific EffectLight deflection: Reflection

Implementation Method 2

a synchronous detection system 60A that detects the irradiation light 600

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentEP3709068B1Optical scanner, display system, and mobile object
Publication Date: 2022.11.23 RICOH CO LTD
  • EP3709068B1 patent drawingFigure 1~2
  • EP3709068B1 patent drawingFigure 3
  • EP3709068B1 patent drawingFigure 4

AI summary

An optical scanner (10) includes a light source (11) configured to emit irradiation light, a light deflector (13) configured to scan the irradiation light emitted from the light source (11) in a first scanning direction and in a second scanning direction intersecting with the first scanning direction, and a photodetector (60A, 60B) configured to detect the irradiation light when the light deflector (13) scans a detection field (60A, 60B). The light source (11) is turned on in a first irradiation field (601A) scanned by the light deflector (13) from the detection field (60A, 60B) to an end (630L, 630R) in the first scanning direction, and the light source (11) is turned on in a second irradiation field (602A) scanned by the light deflector (13) from the end (630L, 630R) in the first scanning direction towards the detection field (60A, 60B). An edge of the first irradiation field (601A) on the detection field (60A, 60B) side is caused to move to get close to the detection field (60A, 60B) from a position away from the detection field (60A, 60B), and an edge of the second irradiation field (602A) on the detection field (60A, 60B) side is caused to move to get close to the detection field (60A, 60B) from a position away from the detection field (60A, 60B).