MEMS Laser White Balance Stabilization
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Solution Overview
Problem
Semiconductor lasers in small-sized projection projectors experience changes in white balance due to temperature variations, affecting light quantity and wavelength, making it difficult to maintain consistent image display.
Innovation Solution
An image display device with a light source, drive unit, reflecting mirror, image processing unit, optical sensor, and temperature sensor that adjusts light quantity and synchronization signals to maintain constant white balance by measuring light and temperature, and applying correction signals to the light source drive unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light quantity of the semiconductor laser is increased to compensate for temperature changes, then the light quantity can be maintained constant, but the white balance shifts due to wavelength changes
Solution Approach 1:
The patent implements a feedback control system that uses an optical sensor to detect the actual light quantity and wavelength of the semiconductor laser, compares these values against target values, and adjusts the drive current accordingly. This closed-loop feedback mechanism allows simultaneous compensation for both light quantity fluctuations and wavelength shifts, resolving the contradiction between maintaining constant light output and preserving white balance.
Solution Approach 2:
The patent dynamically changes the drive current parameters of the semiconductor laser based on temperature measurements and real-time optical characteristics. By adjusting the current magnitude and timing characteristics in response to temperature variations, the system maintains both adequate light quantity and stable wavelength, thereby preserving white balance while compensating for temperature-induced drift.
2Reliability
If the forward current characteristics of the semiconductor laser are adjusted to maintain light quantity, then the light output remains stable, but the wavelength shifts causing white balance changes
Solution Approach 1:
The optical sensor provides real-time feedback on the actual light output and wavelength characteristics of the semiconductor laser. This feedback is processed by the control unit which adjusts the drive current parameters to compensate for both light quantity variations and wavelength shifts, ensuring both reliability of light output and stability of white balance simultaneously.
Solution Approach 2:
The control system performs multiple functions by using a single feedback mechanism to address both light quantity stabilization and wavelength control. The optical sensor and control unit work together to simultaneously manage both parameters, making the system universally capable of maintaining both light output stability and color consistency despite temperature changes.
3Device complexity
If no temperature compensation is applied, then the device complexity is low, but the white balance changes significantly with temperature
Solution Approach 1:
The patent introduces a feedback control system with an optical sensor that continuously monitors the semiconductor laser output and provides signals to the control unit. This feedback mechanism enables automatic temperature compensation by adjusting drive current based on real-time optical characteristics, achieving stable white balance without requiring complex manual calibration or multiple separate control systems.
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 solution effectively reduces temperature-induced changes in white balance, ensuring consistent image display quality by controlling light quantity and wavelength fluctuations.
Implementation Method 1
an optical sensor configured to measure a light quantity of light generated at the light source
Implementation Method 2
a temperature sensor configured to measure a temperature of the light source
Implementation Method 3
a reflecting mirror configured to reflect light generated at the light source and externally project the light
Data Source
AI summary
A change in the white balance caused due to the temperature is reduced in an image display device using MEMS and a laser light source. An image processing unit of the device superposes a signal based on a first measured value of a light quantity at a first temperature on a image signal to be supplied to the laser light source. An amplification factor of the light source drive unit is changed so that a second measured value at a second temperature comes close to the first measured value at the first temperature as a target value based on the second measured value at which the light quantity of light generated at the laser light source is measured at the second temperature different from the first temperature on the signal based on the first measured value.