Laser Projection Display Light Control Feedback Mechanism

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Solution Overview

Problem

Existing laser projection display devices face challenges in stabilizing light intensity due to time degradation and temperature variations in semiconductor lasers, leading to luminance and chromaticity changes that affect the display screen, particularly when adjusting brightness according to environmental conditions.

Innovation Solution

A laser projection display device with a light emission control unit that adjusts the current setting for the semiconductor laser light source using a light sensor to maintain a target light amount, performing multiple light emissions with a predetermined current difference during the fly-back period to optimize current settings and stabilize light control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a current value searching method is used to suppress variation in laser light amount, then light amount control is improved, but measurement precision deteriorates due to errors in target value achievement

Engineering Contradiction:

Improvelight amount control stabilityVSAvoidtarget value accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the light amount detected by the light sensor is fed back to the light emission control unit. This feedback loop enables continuous adjustment of the drive current to achieve the target light amount, resolving the contradiction by using detected values to correct search errors and improve measurement precision while maintaining control stability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical/search-based current value searching method with an optical measurement-based approach. By using a light sensor to directly detect the light amount and comparing it with the target value, the system substitutes the indirect search process with a direct measurement and control approach, improving precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If light control processing is performed to adjust display brightness, then adaptability to environment is improved, but luminance stability deteriorates due to shifts at mode boundaries

Engineering Contradiction:

Improvebrightness adjustment capabilityVSAvoidluminance consistency

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by performing light amount control adjustment before the light control mode changes take effect. The light emission control unit adjusts the drive current in advance based on the detected light amount, ensuring that when the light control mode switches, the luminance remains stable and avoids shifts at boundaries.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The feedback mechanism continuously monitors the actual light amount and adjusts the drive current accordingly. This feedback control ensures that even when light control modes change, the system maintains luminance stability by compensating for any shifts through real-time adjustment based on detected values.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If multiple light emissions are performed with predetermined current difference during fly-back period, then manufacturing precision is improved, but loss of time increases

Engineering Contradiction:

Improvecurrent setting accuracyVSAvoidadjustment time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent utilizes the periodic fly-back period of the scanning system to perform multiple light emissions with different current settings. By scheduling the precision adjustment measurements during the existing periodic fly-back intervals, the system achieves high manufacturing precision without adding significant time loss, as the adjustments occur during already allocated non-display time windows.

Inventive Principle:

Principle #19Periodic action

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 approach effectively stabilizes light amount control and minimizes luminance and chromaticity changes, ensuring a consistent display experience by accurately adjusting current settings to maintain target light values, thus reducing user-perceived brightness and color shifts.

Implementation Method 1

a light sensor detecting a light amount of the laser light generated by the laser light source

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

a laser light source generating laser light of a plurality of colors

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS9961313B2Laser projection display device

Publication Date: 2018.05.01 HITACHI LG DATA STORAGE INC

AI summary

A laser projection display device 1 includes a laser light source driving unit 4 setting a current which drives a laser light source according to an image signal, a light sensor 10 detecting a light amount of the laser light generated by the laser light source 5, and a light emission control unit 22 emitting light by supplying a standard image signal and a current setting signal to the laser light source driving unit and setting the laser light source driving unit such that the light amount detected by the light sensor becomes a target value. The light emission control unit supplies the current setting signal to the laser light source driving unit such that light emission is performed a plurality of times with a predetermined current difference, in a fly-back period in one frame of the image signal.