Projection Apparatus Color Balance Correction via Temperature Feedback
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Solution Overview
Problem
Semiconductor light emitting elements used in projectors experience variations in light emission wavelength and sensitivity with temperature changes, disrupting color balance in projected images, as existing methods fail to accurately correct for these changes.
Innovation Solution
A projection apparatus and method that includes temperature detection and light intensity measurement units to correct light emission intensity for each semiconductor light emitting element, ensuring accurate color balance by using lookup tables to determine correction factors based on measured temperatures and illuminances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If semiconductor light emitting elements are used as light sources, then power consumption and size are improved, but color balance stability deteriorates due to temperature-induced wavelength variations
Solution Approach 1:
The patent implements a feedback control system where an illuminance sensor continuously measures the light output from semiconductor light emitting elements, and a control unit adjusts the drive current to maintain consistent luminance despite temperature-induced wavelength shifts. This closed-loop feedback mechanism resolves the contradiction by automatically compensating for the instability caused by temperature variations.
Solution Approach 2:
The patent changes the operational parameters of semiconductor light emitting elements by adjusting drive current based on measured luminance values. When wavelength shifts cause luminance deviations, the control unit modifies the drive current parameter to compensate, thereby maintaining color balance stability while continuing to use energy-efficient semiconductor light sources.
2Adaptability or versatility
If multiple semiconductor light emitting elements with different wavelengths are combined, then color image capability is improved, but luminance balance becomes difficult to maintain due to temperature sensitivity
Solution Approach 1:
The patent uses an illuminance sensor to measure the luminance output of each semiconductor light emitting element (red, green, blue) and feeds this information back to a control unit. The control unit then adjusts the drive current for each element to achieve and maintain accurate luminance balance, enabling reliable color image projection despite temperature variations affecting multiple elements.
Solution Approach 2:
The patent implements dynamic adjustment of drive currents for multiple semiconductor light emitting elements based on real-time luminance measurements. Rather than using fixed drive currents, the system continuously adapts the operational parameters of each element to maintain accurate color balance, resolving the manufacturing precision issue through dynamic control.
3Measurement precision
If illuminance sensor measurement is used for brightness adjustment, then color balance correction is improved, but measurement accuracy deteriorates due to temperature-induced wavelength shifts
Solution Approach 1:
The patent creates a feedback loop where the illuminance sensor measures luminance and the control unit uses this information to adjust drive currents. The system compensates for temperature-induced measurement errors by dynamically adjusting operational parameters based on the measured values, thereby maintaining accurate brightness control despite wavelength shifts.
Solution Approach 2:
The patent compensates for measurement inaccuracies caused by wavelength shifts by changing the operational parameters (drive currents) of the light emitting elements. When the illuminance sensor detects luminance deviations due to temperature-induced wavelength changes, the control unit adjusts the drive current to restore accurate luminance levels, effectively correcting the measurement information loss.
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 color balance across projected images even with temperature variations of semiconductor light emitting elements, preventing disruptions in color balance and ensuring accurate tone representation.
Implementation Method 1
semiconductor light emitting elements such as light emitting diodes (LEDs) or laser diodes (LDs)
Implementation Method 2
an illuminance sensor 28... measures an illuminance of light
Implementation Method 3
a temperature sensor 29... detects a temperature of the LD 18
Data Source
AI summary
A projection unit projects the optical image formed by the optical image formation unit toward a projection target. A temperature detection unit detects a temperature of each type of the semiconductor light emitting elements during light emission. A measurement unit measures an intensity of light from each type of the semiconductor light emitting elements during light emission. A light emission control unit (a) corrects a measurement result from the measurement unit using a detection result from the temperature detection unit and (b) controls the light emission intensity for each of the semiconductor light emitting elements based on the corrected measurement result.