Projector Light Source Boxes with Dedicated Photodetectors
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Solution Overview
Problem
Existing projector technologies face challenges in maintaining optimal white balance when using solid-state light sources of different colors, especially when driving currents are simultaneously supplied, as the light detection element struggles to detect light from each color separately, making it difficult to adjust light intensity effectively.
Innovation Solution
A projector design with multiple light source boxes, each containing a photodetector and drive units, where a controller adjusts the power supply to maintain the light output at a reference value specific to each color, ensuring accurate detection and adjustment of light intensity for each color, regardless of simultaneous current supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one light detection element is used to detect light from multiple color LEDs simultaneously, then the device complexity is reduced, but the measurement precision of light intensity for each color deteriorates
Solution Approach 1:
The patent divides the light detection function into separate segments by providing one light detection element for each color of LED. This segmentation allows each detection element to be optimized for its specific color wavelength, thereby maintaining high measurement precision while using multiple simple detection elements rather than one complex multi-color detector.
2Productivity
If driving currents are simultaneously supplied to solid-state light sources of respective colors, then the productivity of image display is improved, but the difficulty of detecting and measuring light intensity for each color increases
Solution Approach 1:
The patent assigns separate light detection elements to each color channel, enabling independent measurement of each color's light intensity even when all LEDs are driven simultaneously. This segmentation eliminates the measurement interference that would occur with a single shared detector, allowing simultaneous driving to proceed without compromising measurement accuracy.
Solution Approach 2:
The patent introduces separate light detection elements as intermediaries between the simultaneous light emission and the measurement process. Each detection element acts as a dedicated mediator for its specific color, converting the complex simultaneous multi-color detection problem into multiple simple single-color detection tasks.
3Ease of operation
If the luminance of solid-state light sources is allowed to change with temperature and time, then the ease of operation is improved, but the stability of white balance deteriorates
Solution Approach 1:
The patent implements a feedback control system where light detection elements continuously monitor the actual luminance of each LED, and the controller adjusts the driving currents based on these measurements. This closed-loop feedback compensates for temperature-induced and time-induced luminance changes, maintaining stable white balance while requiring minimal manual intervention from the operator.
Solution Approach 2:
The system performs self-adjustment through automatic feedback control, where the controller autonomously compensates for luminance drift without requiring user intervention. The light detection elements and controller work together to self-correct white balance issues, maintaining stability while keeping the operation simple for the user.
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 solution allows for constant optimal white balance in projectors, regardless of environmental changes or material variations, and supports both time-division and simultaneous driving methods, ensuring accurate light detection and adjustment for each color.
Implementation Method 1
a photodetector that detects light from the solid-state light source is provided within each of the light source boxes
Data Source
AI summary
A projector includes a plurality of light source boxes (1R, 1G, 1B) each accommodating at least one solid-state light source, emission colors of accommodated solid-state light sources being different from each other, a plurality of photodetectors (205c, 206c, 207c) that are provided within respective light source boxes and that detect light from the solid-state light sources, a plurality of drive units (202 to 204) that supply current to solid-state light sources (205b, 206b, 207b) provided within respective light source boxes, and a controller (201) that holds a reference value for the solid-state light source provided within each light source box for each emission color, that causes each drive to supply current to the solid-state light source provided within each light source box, and that adjusts the amount of current output from each drive unit such that the output value of each photodetector is at a reference value which corresponds to the emission color of the solid-state light source which is a corresponding target of light detection.