Split Color Wheel Segment for Blue Laser Phosphor Mixing
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Solution Overview
Problem
Current solid state illuminated projectors using blue laser diodes and phosphor wheels face challenges in achieving aesthetically pleasing color points, particularly with the dominant purplish blue color contribution, due to the use of less expensive blue laser diodes, and suffer from complexity and efficiency issues with existing methods to modify the blue color using cyan phosphors.
Innovation Solution
A color wheel configuration that alternately generates blue light directly from the laser and indirectly through cyan phosphor emission, with a thicker cyan phosphor coating applied uniformly over the reflective surface, allowing for simultaneous direct and indirect blue light contributions, enabling more flexible grayscale intensity settings and improved color point adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a blue laser diode is used to generate blue light directly, then the system achieves high brightness and efficiency, but the color point becomes purplish and aesthetically displeasing
Solution Approach 1:
The blue segment is divided into two functional regions: a first region with cyan phosphor coating for indirect blue light generation, and a second region without phosphor coating for direct blue light transmission. This segmentation allows the system to combine both phosphor-converted blue light (aesthetically pleasing) and direct blue light (bright) to achieve the desired color point while maintaining high brightness.
Solution Approach 2:
Different regions of the blue segment are assigned different properties: the first region has cyan phosphor coating to modify color, while the second region remains transparent to preserve direct blue light transmission. This local differentiation enables simultaneous optimization of color quality and brightness in different spatial zones of the same segment.
2Object-affected harmful factors
If cyan phosphor is used to modify the blue color point, then the color quality improves, but the system complexity and manufacturing difficulty increase
Solution Approach 1:
By dividing the blue segment into two regions with different phosphor coating characteristics, the patent simplifies the manufacturing process. The first region can be coated with uniform cyan phosphor while the second region remains uncoated, allowing for more straightforward manufacturing compared to attempting uniform partial transmission through a single complex coating layer.
3Object-affected harmful factors
If cyan phosphor coating is applied to the blue segment, then the blue color point is modified, but light efficiency decreases due to absorption and re-emission losses
Solution Approach 1:
The blue segment is segmented into a first region with cyan phosphor for color modification and a second region without phosphor for efficient direct light transmission. This segmentation ensures that not all blue light passes through phosphor material, thereby minimizing energy losses from absorption and re-emission while still achieving adequate color point modification through the phosphor-containing region.
Solution Approach 2:
The patent merges the outputs from two different regions: indirectly generated blue light from the phosphor-coated first region and directly transmitted blue light from the uncoated second region. This combination allows the system to benefit from both color modification and high efficiency light transmission, offsetting the energy losses in the phosphor region with the efficient transmission in the non-phosphor region.
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 approach allows for a more uniform and repeatable modification of the blue color point, reducing complexity and improving light efficiency by using a thicker cyan phosphor coating and alternating direct and indirect blue light contributions, enhancing the overall color gamut and image quality.
Implementation Method 1
indirectly through cyan phosphor emission
Implementation Method 2
over the reflective surface
Data Source
AI summary
Apparatus for generating blue color illumination for use in a projection system a color wheel with segments of respective different color light emitting phosphors formed over light non-transmitting portions and at least one blue color generating segment. The blue color generating segment has cyan color light emitting phosphor formed over a light non-transmitting first portion and a second portion that transmits blue laser light through the wheel. A dichroic filter directs blue laser light from a light source onto the respective segments as the color wheel rotates. The light strikes the first and second portions of the blue color generating segment to generate blue light at a color point determined by both blue laser light and phosphor emitted cyan light.