Light Guiding Unit Refractive Index Bridge for Projectors
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Solution Overview
Problem
Existing light source apparatuses face a decrease in light utilization efficiency due to total reflection of light at the interface between the light guiding rod and the angle converter, caused by the lower refractive index of the angle converter compared to the light guiding rod, resulting in reduced light incident on the angle converter.
Innovation Solution
A light guiding unit with a wavelength conversion member and an angle converter where the light guiding member's side surfaces and end surface are buried in the angle converter, increasing the number of interfaces and reducing total reflection by matching the refractive indices, allowing more light to enter the angle converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an angle converter with lower refractive index is used to change light exiting angle, then light extraction efficiency is improved, but light utilization efficiency decreases due to total reflection at the interface
Solution Approach 1:
The patent introduces a bonding member as an intermediary substance between the light guiding rod and the angle converter. This bonding member has a refractive index that is higher than that of the angle converter but lower than or equal to that of the light guiding rod, serving as a refractive index bridge. The intermediary material reduces the refractive index difference at the interface, thereby reducing total internal reflection and allowing more light to enter the angle converter while maintaining the angle conversion function.
Solution Approach 2:
The patent changes the refractive index parameter of the bonding member to optimize light transmission. By selecting a bonding member with a specific refractive index range (higher than the angle converter's refractive index but lower than or equal to the light guiding rod's refractive index), the system achieves optimal light extraction and transmission efficiency at the interface between the light guiding rod and angle converter.
2Productivity
If the refractive index difference between light guiding rod and angle converter is large, then angle conversion function is enhanced, but total reflection increases and light entry to angle converter decreases
Solution Approach 1:
The bonding member acts as a refractive index intermediary that bridges the gap between the light guiding rod and angle converter. It provides a gradual transition in refractive index, reducing the abrupt change that causes total internal reflection, while still maintaining sufficient refractive index difference to achieve effective angle conversion.
Solution Approach 2:
The patent optimizes the refractive index parameter of the bonding member to balance two competing requirements: maintaining enough refractive index difference for effective angle conversion while reducing the refractive index difference sufficient to minimize total internal reflection and maximize light transmission.
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 configuration increases the amount of light entering the angle converter, enhancing light extraction efficiency and utilization, particularly by optimizing the burying depth to maximize fluorescence entry into the illumination homogenizing optical system.
Implementation Method 1
part of the light having exited out of the light guiding rod is disadvantageously totally reflected off the interface between the light guiding rod and the angle converter
Implementation Method 2
an angle converter is provided on the light exiting side of a light guiding rod including a wavelength conversion member to change the light exiting angle
Implementation Method 3
a light guiding rod including a wavelength conversion member
Data Source
AI summary
A light guiding unit includes a light guiding member that light enters and an angle converter that the light from the light guiding member enters. The light guiding member has a side surface and a light exiting end surface which intersects the side surface and via which the light exits. The angle converter includes a light incident section on which the light from the light guiding member is incident, a light exiting section via which the light incident on the angle converter exits, and a reflection section that reflects the light incident via the light incident section toward the light exiting section. The refractive index of the interior of the angle converter is greater than the refractive index of air. The refractive index of the interior of the light guiding member is greater than the refractive index of the interior of the angle converter.