Laser Power Control for Projector Brightness and Safety
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Solution Overview
Problem
Projectors using lasers as a light source face challenges in increasing brightness while maintaining sufficient contrast, especially in bright surroundings, and in adhering to laser safety standards, as the power of laser light emission is difficult to control effectively across different image colors.
Innovation Solution
An image projection apparatus with multiple color lasers, a synthesis element, an optical modulation element, and a controller that adjusts the power of laser beams based on the input image to ensure the power of the projected light does not exceed safety standards, allowing for optimized brightness and compliance with laser safety regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the power of laser light is increased to improve projector brightness, then brightness is improved, but the laser safety standard is violated
Solution Approach 1:
The patent implements dynamic control of laser power output based on the input image signal. The controller adjusts the drive current to the laser diode in real-time according to the brightness and color information of the projected image, allowing the system to operate at high power when needed while maintaining safety standards during normal operation.
Solution Approach 2:
The patent changes the operating parameters of the laser diode by adjusting drive current based on image signal characteristics. The controller modifies parameters such as pulse width modulation duty cycle and current amplitude to achieve optimal brightness while maintaining compliance with laser safety classifications.
2Object-affected harmful factors
If the power of laser light is reduced to satisfy laser safety standards, then safety compliance is improved, but projector brightness deteriorates
Solution Approach 1:
The system dynamically adjusts laser power output based on real-time image signal analysis. By controlling the laser drive current according to the specific requirements of different image content, the system achieves both safety compliance and optimal brightness performance.
Solution Approach 2:
The patent employs periodic pulse-width modulation to control the laser output. The controller divides the projection frame into multiple time slots and applies periodic switching of the laser diode, allowing high power operation during active projection periods while maintaining lower average power levels for safety compliance.
3Device complexity
If the laser operates at constant power without image dependency, then device complexity is reduced, but brightness optimization is lost
Solution Approach 1:
The controller receives feedback from the image signal and adjusts the laser drive current accordingly. The feedback mechanism processes the input image data to determine optimal laser power levels, achieving brightness optimization while maintaining manageable system complexity through integrated control.
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 enables projectors to maintain safety standards while preventing unnecessary power consumption and maximizing brightness, ensuring compliance with laser safety standards by dynamically adjusting laser power according to the input image.
Implementation Method 1
light sources (1, 2, 3) provided for each of a plurality of colors to emit a laser beam in a corresponding color
Implementation Method 2
a synthesis element (4) that synthesizes laser beams in each color emitted by the light sources (1, 2, 3) for each color
Implementation Method 3
an optical modulation element (6) that modulates synthesized light resulting from the synthesis by the synthesis element (4) according to an image signal
Data Source
AI summary
To control a laser used as a light source according to an input image, while satisfying a safety standard, a projector includes lasers provided for each of a plurality of colors, a dichroic mirror that synthesizes laser beams emitted by the lasers, an LCOS panel that modulates synthesized light by the dichroic mirror, and a projection lens that projects the light modulated by the LCOS panel. A processor determines rate of power of the laser beams according to the image signal, determines, according to the rate of the power, an upper limit value of the power of the projected laser beam in each color to the extent that the upper limit value satisfies a safety standard, and adjusts the laser beam in each color emitted by the corresponding laser so as to prevent the projected light beam in each color from exceeding the upper limit value.