Projection Display Blue Light Reflection for Color Temperature Control
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Solution Overview
Problem
Existing projection image display devices face a challenge in switching between high and low color temperature modes without compromising the brightness of the projected image, as using a dark filter to lower color temperature results in reduced image brightness.
Innovation Solution
A projection image display device comprising a blue light source, a phosphor that produces yellow light, and a filter that reflects a portion of the blue light back onto the phosphor, allowing it to produce additional yellow light, thereby maintaining image brightness while adjusting color temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a dark filter is used to lower the color temperature, then the color temperature is reduced, but the brightness of the projected image is lowered
Solution Approach 1:
The patent changes the optical path and light interaction parameters by introducing a reflective filter that redirects blue light onto the phosphor. This parameter change allows the system to maintain brightness while adjusting color temperature, resolving the contradiction between lowering color temperature and maintaining brightness.
Solution Approach 2:
The reflective filter acts as an intermediary element that mediates between the blue light source and the phosphor. By reflecting blue light onto the phosphor, it enables additional yellow light production without blocking the primary light path, thus maintaining brightness while adjusting color temperature.
2Adaptability or versatility
If a dark filter is used to adjust color temperature, then the color temperature changes, but the brightness is reduced
Solution Approach 1:
The patent introduces a dynamic light interaction mechanism where the reflective filter can be positioned to reflect blue light onto the phosphor when color temperature adjustment is needed. This dynamic approach allows the system to switch between normal operation and color temperature adjustment mode without permanent brightness loss.
Solution Approach 2:
The reflective filter serves as a versatile intermediary that enables color temperature adjustment through controlled blue light reflection. This intermediary mechanism provides adaptability for color temperature control while preserving brightness by not blocking the main light path.
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 solution effectively inhibits the lowering of image brightness when switching to low color temperature mode by reflecting a portion of the blue light back onto the phosphor, increasing the yellow light production and maintaining image brightness.
Implementation Method 1
the yellow phosphor is irradiated by a laser light from the blue laser light source and converts the energy of the irradiating laser light into a yellow light of a wavelength band including a red band and a green band
Implementation Method 2
a filter (50) that reflects a portion of the blue illumination light reflected by the phosphor toward the phosphor
Data Source
AI summary
A projection image display device includes: a light source that emits a blue illumination light; a phosphor that produces, in a region irradiated by the blue illumination light, a yellow illumination light including a component in a red band and a component in a green band from a portion of the blue illumination light and that reflects the blue illumination light and the yellow illumination light; and a filter that reflects a portion of the blue illumination light reflected by the phosphor toward the phosphor. The filter reflects the portion of the blue illumination light so as to be imaged at a position displaced from a region on a phosphor surface irradiated by the blue illumination light, and the phosphor produces a yellow illumination light also from the blue illumination light reflected by the filter.