Laser Display Scanning Control for Oblique Projection
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Solution Overview
Problem
Existing display devices face limitations in maintaining image quality when projecting video obliquely, with trapezoidal distortion and increased beam spot diameter issues at higher inclination angles, restricting the projection angle and requiring rapid mirror speed control.
Innovation Solution
A display device configuration that includes a laser light source, condensing lens, swinging mirror, scanning position determining unit, and control unit, which uses pre-calculated scanning waveforms and correction amounts to adjust the scanning line density and lens focus, allowing for equalized scanning and reduced beam spot diameter even at higher inclination angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the inclination angle at the time of oblique projection is increased, then the adaptability of the display device is improved, but the beam spot diameter is enlarged and image quality deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction amounts in a lookup table (LUT) that compensates for beam spot enlargement at different inclination angles. The correction amount LUT stores predetermined correction values based on inclination angle, allowing the system to automatically apply the appropriate correction without real-time calculation, thus maintaining beam spot diameter control while enabling higher inclination angles.
Solution Approach 2:
The patent changes parameters by adjusting the correction amount based on the inclination angle through the correction amount LUT. When the inclination angle changes, the system retrieves the corresponding correction amount from the LUT and applies it to modify the display data, thereby compensating for beam spot diameter variations and maintaining image quality across different projection angles.
2Adaptability or versatility
If the inclination angle at the time of oblique projection is increased, then the adaptability of the display device is improved, but trapezoidal distortion occurs and image quality deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating trapezoidal distortion correction values and storing them in the correction amount LUT. The correction amounts are predetermined for various inclination angles and scanning positions, allowing the system to apply corrections in advance based on the actual projection conditions without requiring complex real-time calculations.
Solution Approach 2:
The patent changes parameters by dynamically adjusting the correction amount retrieved from the LUT based on the inclination angle and scanning position. The correction amount varies with these parameters to compensate for trapezoidal distortion, transforming the distorted image data into a corrected form that maintains geometric accuracy at different projection angles.
3Manufacturing precision
If the swinging speed of the mirror is changed for trapezoidal distortion correction, then the manufacturing precision is improved, but the device complexity increases due to rapid speed control requirements
Solution Approach 1:
The patent replaces the mechanical approach of dynamically adjusting mirror swinging speed with a data processing approach. Instead of controlling the mirror's mechanical speed to correct trapezoidal distortion, the system uses a correction amount LUT to pre-calculate and store correction values, then applies these corrections to the display data. This substitutes complex mechanical speed control with simpler data retrieval and application.
Solution Approach 2:
The patent changes the approach from mechanical parameter control (mirror speed) to data parameter correction (correction amount in LUT). By storing correction amounts in the LUT and applying them to display data, the system achieves trapezoidal distortion correction without requiring rapid changes in mirror swinging speed, thereby reducing device complexity.
4Device complexity
If the scanning line density is not equalized, then the device complexity is reduced, but the manufacturing precision of the display deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating scanning line density correction values and storing them in the correction amount LUT. The correction amounts are predetermined for various scanning positions and inclination angles, allowing the system to equalize scanning line density by retrieving and applying the appropriate correction values without requiring complex real-time scanning control adjustments.
Solution Approach 2:
The patent changes parameters by adjusting the correction amount in the LUT based on scanning position and inclination angle. This correction compensates for variations in scanning line density caused by oblique projection, equalizing the line density across the display area without requiring complex changes to the scanning control mechanism itself.
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
This configuration maintains image quality and increases the permissible inclination angle for oblique projection without rapid mirror speed changes, addressing trapezoidal distortion and beam spot enlargement issues.
Implementation Method 1
a condensing lens which condenses the laser light generated by the laser light source on the display unit
Implementation Method 2
a swinging mirror on which the laser light passing through the condensing lens is incident and which reflects the laser light while scanning in a vertical direction and a horizontal direction of the image
Data Source
AI summary
The present invention prevents image quality degradation due to pixel enlargement even when using an increased angle of inclination on projecting an image obliquely from a laser scanning display device. A swing mirror is controlled so that the scanning line density in the vertical direction of a display section is uniform in accordance with information including the angle of inclination, the distance of projection, and the display size of the display device with respect to the display section. A lens control driver is controlled so that a collecting lens has a focal point on the display section in accordance with a scanning position in the vertical direction of the swing mirror. The swing mirror or an image correction processing unit is controlled so that a display size in the horizontal direction of a display image on the display section is uniform regardless of the scanning position in the vertical direction.