Laser Projection Display White Balance Stability During Dimming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser projection display devices using semiconductor lasers face issues with white balance variations due to dimming operations, as they do not account for changes in light-forward current characteristics, leading to inconsistent brightness and image quality.
Innovation Solution
A laser projection display device is designed with an optical sensor and image processing unit that detects light levels and adjusts drive signals to maintain constant white balance during dimming operations by using multiple semiconductor lasers and dichroic mirrors for RGB light synthesis, along with a light-emission control unit that adjusts current control ranges and LUTs to manage brightness and grayscale effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If dimming operation is performed to change brightness of display image, then optical intensity is adjusted, but white balance varies due to variation in amount of light-forward current characteristics of semiconductor laser
Solution Approach 1:
The patent applies preliminary action by performing grayscale correction during the flyback period (non-video display period) before the actual video display begins. The system extrapolates test signals during this preliminary phase, calculates actual grayscale characteristics, and stores correction data in advance, so that when dimming operation occurs during video display, the white balance is already corrected and remains stable.
Solution Approach 2:
The patent implements feedback by measuring actual grayscale characteristics during the flyback period, comparing them with ideal characteristics, and using this feedback information to automatically perform grayscale correction during normal operation. The system continuously monitors and adjusts the semiconductor laser characteristics based on measured data, ensuring white balance stability even during dimming operations.
2Manufacturing precision
If grayscale correction is performed by extrapolating test signal during flyback period, then actual grayscale characteristics are calculated and stored, but there is no consideration for dimming operation and white balance still varies
Solution Approach 1:
The patent applies dynamics by making the grayscale correction system adaptive to different operating conditions including dimming operations. The system dynamically adjusts the correction parameters based on the currently selected LUT (Look-Up Table) configuration, which corresponds to different brightness levels. When dimming changes the brightness level, the system switches to the appropriate LUT that has been pre-calculated for that brightness condition, maintaining white balance stability across dynamic operating states.
3Adaptability or versatility
If multiple LUTs are prepared for different maximum amount of light settings, then brightness can be adjusted, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing multiple LUTs during the flyback period for different maximum amount of light settings (different brightness levels). Instead of calculating corrections in real-time during video display, the system prepares all necessary correction data in advance and stores them in memory. When dimming operation changes the brightness level, the system simply switches to the pre-prepared LUT corresponding to that brightness level, avoiding complex real-time calculations while maintaining adaptability.
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 reduces white balance variations and maintains image quality by dynamically adjusting light output and current control ranges, ensuring consistent brightness and minimizing grayscale loss during dimming operations.
Implementation Method 1
an optical sensor that detects the amount of light of the laser light beams which are generated by the laser light source
Implementation Method 2
using multiple semiconductor lasers and dichroic mirrors for RGB light synthesis
Data Source
AI summary
The laser projection display device includes: a photo-sensor for detecting the quantity of laser light generated by the laser light source; and an image processing unit for processing a drive signal on the basis of the quantity of light of the detected laser light and supplying the processed drive signal to a driving unit for the laser light source. Right after the dimming, the image processing unit supplies the drive signal to the driving unit for the laser light source on the basis of the quantity of light of the detected laser light within a second execution cycle shorter than a first execution cycle which is the execution cycle used during the normal operation.