Laser Display Stray Light Control via APC Area Segmentation
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Solution Overview
Problem
Laser beams used in Head Up Displays (HUD) scatter as stray light within enclosures, causing noticeable interference with rendered images, especially in low-peripheral brightness environments like nighttime driving.
Innovation Solution
An image display apparatus and method that adjusts laser beam output values by identifying and controlling Auto Power Control (APC) areas outside the rendering range, using a brightness detecting unit to determine APC areas and control laser diodes to minimize stray light influence, with a configuration that blocks stray light from reaching the projection surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser beams are emitted for adjusting output values inside an enclosure, then the output values can be calibrated, but stray light scatters and degrades image quality
Solution Approach 1:
The patent divides the scanning range into multiple sections and selectively emits laser beams only in specific sections that do not cause stray light to reach the projection surface. This segmentation approach allows output calibration while avoiding stray light interference in the image display area.
Solution Approach 2:
The patent applies different emission strategies to different spatial regions. Laser beams are emitted in certain sections for calibration purposes while avoiding other sections where emission would cause stray light to interfere with the projected image, creating localized quality control in different areas of the scanning range.
2Object-affected harmful factors
If an enclosure is used to block laser beams during adjustment, then stray light is contained, but the system complexity increases
Solution Approach 1:
The patent extracts the stray light blocking function from a physical enclosure structure and replaces it with selective laser beam emission control. By using software/control logic to determine which sections to emit in, the system achieves stray light containment without adding mechanical enclosure complexity.
Solution Approach 2:
The patent replaces the mechanical enclosure system with a control-based system that uses scanning position information and section division logic to prevent stray light generation. This substitution eliminates the need for additional mechanical blocking structures while achieving the same stray light containment effect.
3Measurement precision
If laser beams are emitted in all sections for calibration, then calibration is comprehensive, but stray light interference increases
Solution Approach 1:
The patent performs calibration using only a partial set of scanning sections rather than all sections. By selecting specific sections that do not cause stray light to reach the projection surface, the system achieves sufficient calibration accuracy without the excessive action of emitting in all sections, thereby avoiding stray light interference.
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 effectively reduces stray light interference to an unnoticeable level, ensuring high-quality HUD displays even in low-light conditions.
Implementation Method 1
a brightness detecting unit to detect a brightness distribution in a rendering area in which an image is rendered
Implementation Method 2
Laser scanning image display apparatuses that reflect laser beams on Micro Electro Mechanical System (MEMS) mirrors to scan the laser beams and project images
Implementation Method 3
control laser diodes to minimize stray light influence
Implementation Method 4
reflect laser beams on Micro Electro Mechanical System (MEMS) mirrors to scan the laser beams
Data Source
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AI summary
An image display apparatus (100 or 800) includes a laser light source unit (164), a scan mirror unit (170), a rendering control unit (132), a detecting unit (122 or 145), and an output adjusting control unit (134). The rendering control unit (132) controls the laser light source unit (164) in such a way that a display image is rendered in a range smaller than a scan range of the scan mirror unit (170) based on input display image data. The detection unit (122 or 145) detects a range to be a reference for setting a laser beam output position for adjusting an output of the laser beams based on the display image data. The output adjusting control unit (134) controls the laser light source unit (164) in such a way that the laser beams for adjusting an output of the laser beams are output at a position outside the range where the display image is rendered in the scan range of the scan mirror unit (170), and the position is based on the range detected by the detecting unit (122 or 145).