Phosphor Wavelength-Conversion Projector for Focus-Free Speckle Reduction
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Solution Overview
Problem
Existing projectors require focusing operations when the distance to the projection surface changes, leading to potential image blur and speckle noise due to high-coherence projection light interference.
Innovation Solution
A projector design that includes a first light source device with a wavelength conversion member and an exit part configured to emit light with reduced coherence, using a tapered structure to enhance light extraction efficiency and reduce speckle noise, allowing focus-free projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If laser beam is used for projection light, then directionality is improved and focus-free projection is enabled, but coherence increases causing speckle noise
Solution Approach 1:
The light source is divided into multiple independent laser beams corresponding to different pixels, with each beam having slightly different emission characteristics. This segmentation reduces overall coherence while maintaining the directional properties needed for focus-free projection.
Solution Approach 2:
Different regions of the light source emit light with locally optimized properties - the exit part creates localized emission zones with controlled coherence characteristics, allowing each pixel's light to maintain directionality while the overall system reduces speckle noise through varied local coherence properties.
2Object-generated harmful factors
If conventional light source is used, then speckle noise is reduced, but directionality decreases requiring focusing optics
Solution Approach 1:
The patent replaces conventional mechanical focusing optics with a light source design that inherently provides directional emission through its structural configuration - the exit part geometry and phosphor arrangement create automatic directionality without requiring additional optical elements.
3Measurement precision
If focusing optics are added, then image focus is improved, but device complexity increases
Solution Approach 1:
The light source structure itself performs the focusing function that would otherwise require separate optical components. The exit part geometry and internal light propagation paths are designed to automatically provide the necessary beam directionality, making the system self-sufficient and eliminating additional complexity.
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 projector achieves clear, speckle-noise-reduced images without the need for focusing optics, maintaining image quality across varying distances.
Implementation Method 1
a wavelength conversion member which includes a phosphor, and which is configured to convert the first light emitted from the light emitting element into second light having a second wavelength band different from the first wavelength band
Data Source
AI summary
A projector according to the present disclosure is a projector configured to project an image on a projection target in a focus-free state, including a first light source device, and a light modulation element configured to modulate light emitted from the first light source device. The first light source device includes a light emitting element configured to emit first light having a first wavelength band, a wavelength conversion member which includes a phosphor, and which is configured to convert the first light emitted from the light emitting element into second light having a second wavelength band, and an exit part which is disposed along a central axis of the wavelength conversion member, and which is configured to emit the second light generated by the wavelength conversion member.