HUD Light Source Device Power Balance Control

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Solution Overview

Problem

Existing heads-up displays (HUDs) face challenges in setting a desired power balance between laser beams of different wavelengths, leading to limitations in generating high-color-reproducibility desired colored light.

Innovation Solution

The implementation of a light-source device with a semiconductor laser unit that modulates laser beams of red, green, and blue colors, using a light deflector and scanning mirror system to adjust the power balance and luminance based on ambient temperature and external light conditions, allowing for precise control of light emission through a control system that includes a FPGA, CPU, and MEMS controller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If semiconductor lasers with different wavelengths are used to generate colored light, then color variety is improved, but power balance control becomes difficult

Engineering Contradiction:
Improvecolor varietyVSAvoidpower balance control
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The patent employs feedback control by detecting the actual light output of each semiconductor laser and adjusting the drive current accordingly. The control unit receives light amount information from detectors and modifies the drive signals to achieve the desired power balance between different wavelength lasers, thereby resolving the control difficulty while maintaining color variety.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the drive current parameters for each semiconductor laser based on detected light amounts and temperature conditions. By dynamically adjusting electrical parameters (current magnitude and timing) rather than physical parameters, the system achieves precise power balance control across multiple wavelengths without complicating the manufacturing process.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If power balance between laser beams is adjusted for color accuracy, then color reproducibility is improved, but system complexity increases

Engineering Contradiction:
Improvecolor reproducibilityVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses a universal control unit that handles multiple functions: it controls drive currents for all semiconductor lasers, processes detection signals from all light detectors, performs temperature compensation, and calculates power balance adjustments. This multi-functional approach achieves precise color reproducibility without proportionally increasing system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the control functions for multiple lasers into a single integrated control unit, and merges the detection and adjustment processes into a unified feedback loop. By combining related functions rather than implementing separate systems for each laser, the patent achieves high color reproducibility while keeping the overall system complexity manageable.

Inventive Principle:
Principle #5Merging (Combining)

3Stability of the object's composition

If ambient temperature compensation is implemented, then light output stability is improved, but measurement and control complexity increases

Engineering Contradiction:
Improvelight output stabilityVSAvoidtemperature measurement and control
Core Design Contradiction:
Stability of the object's compositionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements self-service temperature compensation where the system uses its own temperature sensors and control logic to automatically detect temperature changes and adjust laser output accordingly. The control unit monitors temperature and autonomously modifies drive currents to maintain stable light output, eliminating the need for external temperature control systems and reducing measurement complexity.

Inventive Principle:
Principle #25Self-service

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 solution enables the generation of desired colored light with improved color reproducibility and visibility, adapting to varying ambient conditions and external light levels, enhancing the display quality of virtual images in HUDs.

Implementation Method 1

a light source unit (11) including three semiconductor lasers (111R, 111G, and 111B) that emit light beams having different wavelengths

Methodology Applied
Scientific EffectLight emission from semiconductor laser: Light Emitting Diode

Implementation Method 2

a light deflector (15) and a scanning mirror (20)

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3293564B1Light-source device, image display apparatus, and mobile object
Publication Date: 2020.07.22 RICOH CO LTD
  • EP3293564B1 patent drawingFigure 1
  • EP3293564B1 patent drawingFigure 2
  • EP3293564B1 patent drawingFigure 3

AI summary

A light-source device (300) including a light-emitting element (111R, 111G, and 111B) to emit light, a light-receiving system (LR), an acquisition unit (700a), a setting unit (700b), and an adjuster (700c). The light-receiving system (LR) receives the light emitted from the light emitting element (111R, 111G, and 111B). The acquisition unit (700a) acquires a wavelength of the light emitted from the light emitting element (111R, 111 G, and 111B). The setting unit (700b) sets a target value of an amount of the light received by the light-receiving system (111R, 111G, and 111B) based on the wavelength acquired by the acquisition unit (700a). The adjuster (700c) adjusts an amount of the light emitted from the light emitting element (111R, 111 G, and 111B) such that the amount of the light reaches the target value of the light that is set with the setting unit (700b).