Projection Apparatus Power Control for Thermal Luminance Correction
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Solution Overview
Problem
Projection image quality degrades due to thermal fluctuations in light sources like LEDs and semiconductor lasers, which cause variations in luminance during color sequential projection.
Innovation Solution
A projection apparatus and method that adjusts power supply to light-emitting devices to correct luminance decreases caused by heat generation, using current value waveforms that account for heat accumulation across fields, and includes sensors to measure and adjust for deviations in light quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If full-level current value is passed through the R-LED in the R field period to maintain light quantity, then luminance is improved, but heat generation increases causing rapid decrease in amount of luminescence
Solution Approach 1:
The control apparatus pre-calculates and stores correction values for the drive current before projection. These correction values are determined in advance based on the relationship between drive current and light quantity characteristics, allowing the system to compensate for heat-induced luminance degradation without real-time measurement delays
Solution Approach 2:
The control apparatus measures the actual light quantity from each color field and uses this feedback to adjust the drive current for subsequent fields. By comparing measured light quantity against target values, the system dynamically corrects current levels to maintain consistent luminance across R, G, and B fields despite thermal fluctuations
2Temperature
If current value is decreased from full level in the G field to reduce heat generation, then heat generation is reduced, but amount of luminescence decreases largely immediately after field changes
Solution Approach 1:
The control apparatus applies preliminary anti-action by pre-increasing the drive current in the G field based on stored correction values. This anticipatory adjustment compensates for the expected luminance drop that would occur due to heat accumulation from previous fields, ensuring smooth transitions without visible flicker or brightness variation
Solution Approach 2:
The system dynamically adjusts drive current levels for each color field based on accumulated heat effects. Rather than using fixed current values, the control apparatus varies current levels adaptively across R, G, and B fields, optimizing the balance between heat generation and luminance output for each transition
3Ease of operation
If previously set power is supplied to the light source, then power control is simple, but amount of luminescence fluctuates by influence of heat generation degrading projection image quality
Solution Approach 1:
The control apparatus performs self-service by automatically measuring light quantity and adjusting drive currents without requiring manual intervention. The system autonomously calculates correction values, stores them in memory, and applies them across color fields, maintaining high image quality while simplifying operation through automated compensation for thermal effects
Solution Approach 2:
The system changes the drive current parameter dynamically based on measured light quantity and stored correction characteristics. By adjusting current levels as a variable parameter rather than maintaining a fixed power setting, the system compensates for thermal degradation while keeping the control interface 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
Maintains consistent light quantity across fields, preventing thermal fluctuations from degrading image quality and ensuring stable projection performance.
Implementation Method 1
a plurality of light-emitting devices for respectively emitting lights of a plurality of colors
Implementation Method 2
a decrease in luminance due to heat generation of the plurality of light-emitting devices
Data Source
AI summary
There is provided a projection apparatus including a plurality of light-emitting devices for respectively emitting lights of a plurality of colors, a projecting unit for forming an optical image of a plurality of color components for each frame and sequentially projecting the optical image, and a power control unit for adjusting power to be supplied to the plurality of light-emitting devices to correct a decrease in luminance due to heat generation of the plurality of light-emitting devices.