Laser Display Device Stabilizing Output to Reduce Speckle Noise
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Solution Overview
Problem
Existing display devices with laser beam generation capabilities face issues of brightness unevenness and speckle noise due to unstable laser outputs during relaxation oscillation, which affect the quality of projected images.
Innovation Solution
A display device with a laser beam generation portion that continuously supplies current for a period longer than the initial relaxation oscillation period to stabilize output, and controls the output to stop at least once during scanning of each image forming element, thereby reducing brightness unevenness and speckle noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If laser beams of relaxation oscillation states are used to project pictures, then speckle noise is suppressed, but brightness unevenness occurs in the projected picture
Solution Approach 1:
The patent applies periodic action by oscillating the laser beams at a frequency between 100 Hz to 1000 Hz during the period when relaxation oscillation occurs. This periodic oscillation prevents the laser beams from remaining in a static interference state, thereby suppressing speckle noise while maintaining stable brightness output through controlled temporal variation
Solution Approach 2:
The patent changes the operational parameters of the laser diodes by supplying modulated current that induces relaxation oscillation. By controlling the current modulation frequency and amplitude, the system transforms the laser output characteristics to achieve both speckle noise suppression and brightness uniformity simultaneously
2Illumination intensity
If current is continuously supplied to laser beam generation portion for period longer than first period, then brightness stability is improved, but speckle noise may increase
Solution Approach 1:
The control portion implements periodic oscillation of the laser beams at frequencies between 100 Hz to 1000 Hz during the extended current supply period. This periodic modulation prevents coherent interference patterns from forming, thereby suppressing speckle noise while the extended duration ensures brightness stability is achieved
Solution Approach 2:
The system transitions from a static laser operation mode to a dynamic oscillating mode. By continuously modulating the laser beam parameters through periodic oscillation, the system adapts to prevent speckle noise formation while maintaining stable average brightness output over the extended operation period
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 achieves stable brightness and reduced speckle noise by generating a stable laser output and preventing interference, ensuring consistent image quality and minimizing color unevenness at image boundaries.
Implementation Method 1
a laser beam generation portion supplied with current thereby outputting a laser beam
Implementation Method 2
a projection portion projecting an image formed by a plurality of image forming elements on an arbitrary projection area by scanning the laser beam
Data Source
AI summary
Disclosed is a display device capable of inhibiting a projected picture from occurrence of brightness unevenness while reducing speckle noise. The display device (100) includes a control portion (15) continuously supplying current to a laser beam generation portion (12, 13, 14) nonstop for a period longer than a first period thereby controlling the laser beam generation portion to output the laser beam and controlling the laser beam generation portion to stop the output of the laser beam at least once in a second period scanning one image forming element (1, 2).