Servo Feedback Control for Scanning Beam Display Alignment
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Solution Overview
Problem
Scanning-beam display systems face challenges in maintaining precise alignment and image quality due to changes in the laser beam position over time, caused by factors like temperature fluctuations, humidity, and mechanical jitter, which can lead to misalignment and color shifts in the displayed images.
Innovation Solution
The implementation of a servo control system using an invisible servo beam and optical servo sensors to monitor the position of the servo beam and adjust the timing of the excitation beam pulses, ensuring precise alignment and maintaining image quality by using reference marks and dynamic focusing mechanisms to correct for distortions and misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a scanning beam display system uses a light-emitting screen with fluorescent materials, then the screen can emit visible light to form images, but the alignment of the scanning beam may drift over time due to temperature fluctuations, humidity, and mechanical jitter, leading to misalignment and color shifts
Solution Approach 1:
The patent employs an optical servo sensor to detect the position of the scanning beam by receiving reflected light from reference marks on the screen. The sensor generates a monitor signal that is fed back to a control unit, which dynamically adjusts the timing of excitation beam pulses to correct alignment drift. This closed-loop feedback mechanism continuously compensates for beam position variations caused by environmental factors and mechanical jitter, maintaining precise alignment without affecting the visible light emission from fluorescent materials.
Solution Approach 2:
The patent introduces an intermediary invisible servo beam that is scanned along with the excitation beam to interact with optically reflective reference marks on the screen. The servo beam serves as a mediator between the scanning system and the optical servo sensor, enabling position detection without directly interfering with the visible image formation. This intermediary approach allows precise alignment monitoring while maintaining the primary function of visible light emission from the light-emitting screen.
2Manufacturing precision
If the system dynamically adjusts beam timing to correct alignment drift, then alignment precision is maintained, but the system complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The patent merges the servo control function with the existing scanning beam system by using the same scanning optics to scan both the excitation beam and the invisible servo beam along identical or overlapping paths. The optical servo sensor is positioned to receive reflected light from the same screen area that displays images, combining imaging and alignment monitoring functions in a single optical path. This merging approach reduces the need for separate, independent alignment systems, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The scanning beam system is designed to perform multiple functions: the excitation beam illuminates fluorescent materials to form visible images, while the co-scanned invisible servo beam simultaneously serves as a positioning probe that interacts with reference marks for alignment monitoring. The optical servo sensor and control unit serve dual purposes by monitoring both beam position and providing feedback for real-time alignment correction. This multi-functionality approach allows the system to maintain high alignment precision without proportionally increasing complexity, as single components perform multiple roles.
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 maintains the alignment of the scanning beam on the screen, reducing visible effects of misalignment and ensuring consistent image quality by dynamically adjusting the beam positioning and focusing, thus improving the overall performance and reliability of the scanning beam display system.
Implementation Method 1
parallel light-emitting stripes which absorb light of the excitation beam to emit visible light to produce images
Implementation Method 2
Each stripe divider is optically reflective. An optical servo sensor is positioned to receive light of the servo beam scanning on the screen including light reflected by the stripe dividers
Data Source
AI summary
Scanning beam display systems that scan at least one invisible servo beam and an excitation beam onto a screen that emits visible light under excitation of the light of the excitation beam and control optical alignment of the excitation beam based on positioning of the servo beam on the screen via a feedback control.