Phosphor Wheel Flicker Control via Back-Surface Detection
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Solution Overview
Problem
Light source devices with phosphor wheels experience flicker due to variations in phosphor layer thickness and concentration, leading to cyclic changes in fluorescent light intensity, which can be exacerbated by damage or gaps in the phosphor layer, and existing solutions that address this issue reduce the intensity of illumination light.
Innovation Solution
A light source device with a phosphor rotating body, a first excitation light source, a detection light generation unit, an optical detection unit, and a control unit that adjusts the intensity of the excitation light based on detection signals from a second position on the phosphor wheel, ensuring uniform illumination without blocking the fluorescent light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light sensor is arranged in the vicinity of the collimator lens to detect fluorescent light for controlling excitation light intensity, then flicker can be prevented, but the intensity of the illumination light is decreased because the light sensor blocks a portion of the fluorescent light
Solution Approach 1:
The light sensor is moved from the optical path of the fluorescent light (near the collimator lens) to a different spatial dimension (the back surface of the phosphor wheel). This allows the sensor to detect fluorescent light for flicker prevention without blocking the illumination light path, thereby resolving the contradiction between flicker prevention and maintaining illumination intensity
Solution Approach 2:
The phosphor wheel itself serves as an intermediary structure that enables the light sensor to be positioned on its back surface. This intermediary arrangement allows the sensor to access fluorescent light emitted by the phosphor wheel without interfering with the forward-directed illumination light, thus preventing flicker while maintaining full illumination intensity
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
Prevents flicker by maintaining uniform fluorescent light intensity and preventing phosphor deterioration, while ensuring the illumination light intensity is not reduced, thus addressing the cyclic changes caused by thickness variations, damage, or gaps in the phosphor layer.
Implementation Method 1
a phosphor layer that is formed on the wheel surface and that contains a phosphor that emits fluorescent light in response to excitation light
Implementation Method 2
The light sensor converts the fluorescent light to an electrical signal, and this output signal is proportional to the intensity of the fluorescent light
Data Source
AI summary
A light source device includes: a phosphor rotating body on which a phosphor that is formed on a surface and that is used in a rotating state with an axis of rotation that is perpendicular to the surface; a first excitation light source that generates first fluorescent light by irradiating first excitation light upon a first position that is separated from the center of rotation on the surface; a detection light generation unit that irradiates detection light upon a second position that is separated from the center of rotation on the surface and that differs from the first position; an optical detection unit that supplies a detection signal corresponding to emission light emitted from the phosphor rotating body in response to the detection light; and a control unit that receives the detection signal and controls the intensity of the first excitation light on the basis of the detection signal.