Light Pulse Feedback System for Projection Optics
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Solution Overview
Problem
Laser-phosphor projection systems face non-linearity in light output due to thermal variations and speed control jitter in phosphor wheels, leading to inconsistent light pulses that are not adequately linearized, especially in high dynamic range projection applications.
Innovation Solution
A light pulse system with a feedback mechanism that includes a pump laser, current drive, conversion element, transmission element, and control unit to calibrate and control light pulses by measuring energy and adjusting amplitude and width based on bit plane data, ensuring consistent light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a spinning phosphor wheel is used to distribute thermal load, then thermal management is improved, but light output consistency deteriorates due to thermal variations and speed control jitter
Solution Approach 1:
The patent implements a feedback system where a detector measures the actual light output from the phosphor wheel and sends signals to a control unit. The control unit adjusts the pump laser pulse width dynamically based on these measurements, compensating for variations caused by thermal effects and speed jitter in the spinning phosphor wheel. This closed-loop feedback mechanism maintains consistent light output despite the mechanical imperfections of the rotating wheel.
Solution Approach 2:
The system dynamically changes the pulse width parameter of the pump laser based on real-time feedback from the detector. By adjusting this parameter in response to measured light output variations, the system compensates for thermal drift and speed variations in the phosphor wheel, maintaining consistent projection output without requiring perfect mechanical stability.
2Loss of time
If the pump laser is pulsed synchronously to bit planes, then projection timing is improved, but light output linearity deteriorates due to intensity variations around the wheel circumference
Solution Approach 1:
The feedback detector continuously monitors the actual light intensity produced by the phosphor wheel at each bit plane timing interval. The control unit uses this information to adjust the pump laser pulse width dynamically, ensuring that each bit plane receives the correct amount of light energy despite variations in phosphor wheel intensity around its circumference. This maintains both timing synchronization and output linearity.
Solution Approach 2:
Instead of using a fixed pump laser pulse width, the system dynamically adjusts the pulse width based on real-time feedback from the detector. This dynamic adaptation allows the system to maintain accurate timing synchronization with bit planes while simultaneously compensating for intensity variations in the phosphor wheel, achieving both goals that were previously contradictory.
3Reliability
If current methods to linearize the response are used, then light output consistency is improved, but system complexity increases due to requirements for consistent wheel rotation and speed control
Solution Approach 1:
The patent uses a feedback-based approach that simplifies the mechanical requirements. Instead of needing highly precise speed control mechanisms and consistent wheel rotation, the system simply measures the actual light output and adjusts the pump laser accordingly. This feedback mechanism achieves linearization and consistency without requiring complex mechanical precision, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The patent replaces complex mechanical speed control mechanisms with an electronic feedback system. Rather than relying on precise mechanical timing and rotation control, the system uses optical detection and electronic adjustment of laser pulse width to achieve the same goal. This substitution of mechanical complexity with electronic control simplifies the overall system while maintaining light output consistency.
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 system ensures consistent and precise light pulses by dynamically adjusting the amplitude and width of light pulses, accommodating thermal variations and speed control jitter, thereby improving the accuracy and consistency of light output for projection systems.
Implementation Method 1
the light from a pump laser is directed towards a phosphor material. The phosphor is typically bonded to a substrate and mounted on a spinning wheel
Implementation Method 2
the detector comprises a photodiode configured to receive the second part of the active light pulse and convert it to an electric current
Implementation Method 3
an integrator coupled to the photodiode to receive the electric current and to integrate the electric current to determine the total measure of energy of the active light pulse
Implementation Method 4
the transmission element comprises a partially transmissive mirror configured to reflect the first part of the active light pulse to the projection optics system and transmit the second part of the active light pulse to the feedback system
Data Source
AI summary
A system and method for controlling the energy of light pulses for use with a projection optics system is provided. The system includes a light source configured to emit light pulses, a transmission element configured to transmit a first part and a second part of an active light pulse, the first part being transmitted to the projection optics system, and a feedback system including a detector configured to receive the second part of the active light pulse and determine a total measure of energy of the active light pulse, and a control unit configured to receive the total measure of energy and in response control an amplitude of a subsequent light pulse. In some implementations, the control unit may additionally set a threshold value for communication to a comparator to compare against the total measure of energy and in response control the width of the active light pulse.