Projector Light Sources Using Time Division for High Luminance
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Solution Overview
Problem
Projectors with solid-state light sources face limitations in achieving high luminance due to etendue constraints and heat generation, leading to unnatural color balance and reduced picture quality, and existing solutions complicate miniaturization, increase costs, and power consumption.
Innovation Solution
A projector configuration with multiple solid-state light sources of different colors sharing the same light path, where some sources are operated in time division to increase luminance without mechanical switching, using dichroic prisms to manage light paths and polarization to enhance efficiency and reduce etendue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the drive current of red and green LEDs is increased to achieve higher luminance, then the luminance increases, but heat generation increases causing thermal saturation that limits further luminance improvement
Solution Approach 1:
The patent applies periodic action by operating red and green LEDs in time-division mode rather than continuously. The control unit alternates between driving red LEDs and green LEDs at different time intervals, allowing each LED to be driven at high current for short periods to achieve high luminance while having sufficient cooling time between pulses to prevent thermal saturation. This periodic operation resolves the contradiction between achieving high luminance and managing heat generation.
2Illumination intensity
If red or green LEDs are arranged in an array to increase optical output, then the optical output increases, but the etendue constraint prevents effective utilization of additional light
Solution Approach 1:
The patent applies segmentation by dividing the single LED array into multiple independently controllable LED groups (red LED groups and green LED groups). Each group can be driven separately in time-division mode, allowing the system to utilize the full optical output of each LED without violating etendue constraints. The segmentation enables effective use of multiple LEDs by controlling them in sequence rather than simultaneously, resolving the contradiction between increasing optical output and etendue limitations.
3Manufacturing precision
If the output of blue LED is controlled to achieve ideal white balance, then color accuracy improves, but the overall luminance is limited by the maximum output of red or green LEDs
Solution Approach 1:
The patent applies periodic action by time-division multiplexing red and green LEDs, allowing each to operate at maximum output during their respective time slots. The blue LED operates continuously or in synchronized intervals. This periodic operation enables the system to achieve both accurate white balance (by controlling blue LED output relative to the maximum output of red/green LEDs) and high overall luminance (by accumulating light output across all three colors over time), resolving the contradiction between color accuracy and overall brightness.
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 configuration achieves high luminance with improved color balance, reduces power consumption, and simplifies the design for smaller, cost-effective projectors with enhanced picture quality and shock resistance.
Implementation Method 1
a first illumination unit that includes a first solid-state light source that emits light of a first color and a second solid-state light source that emits light of a second color that differs from the first color and that irradiates light of the first and second colors that is emitted from the first and second solid-state light sources upon the first display element by way of the same light path
Implementation Method 2
a first solid-state light source that emits light of a first color and a second solid-state light source that emits light of a second color
Data Source
AI summary
Green and red light from first green and red light sources light a first element. Green and red light from second green and red light sources light a second element. Blue light from a blue light source light a third element. A control unit causes an image of a first video signal to be displayed on the first element during lighting of first red source, and causes an image of a second video signal to be displayed on the first element during lighting of the first green source. The unit causes an image of the first signal to be displayed on the second element during lighting of the second red source, and causes an image of the second signal to be displayed on the second element during lighting of the second green source. The unit causes an image of a third video signal to be displayed on the third element.