Laser Line Generator PWM Control for Safe Beam Intersections

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Solution Overview

Problem

Existing laser line generators lack the ability to efficiently manage beam intensity when generating lines and dots on multiple surfaces simultaneously, often resulting in excessive intensity at intersection points, which can be detrimental for accurate construction layout tasks.

Innovation Solution

The laser line generating device employs a gimbal assembly with multiple laser modules and pulse-width-modulation (PWM) duty cycles to independently control the intensity of horizontal and vertical lines, ensuring that the combined intensity at intersection points remains within safe limits by staggering and adjusting the duty cycles of the diodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple laser modules operate simultaneously to generate lines and dots on multiple surfaces, then productivity and functionality are improved, but the intensity at intersection points becomes excessive

Engineering Contradiction:
Improveability to generate lines and dots on multiple surfaces simultaneouslyVSAvoidintensity at intersection points
Core Design Contradiction:
ProductivityVSIllumination intensity

Solution Approach 1:

The patent applies periodic action by using pulse-width modulation (PWM) to alternately activate different laser modules in time-multiplexed sequences. Instead of all modules operating continuously simultaneously, they are activated in staggered time intervals, which reduces the cumulative intensity at intersection points while maintaining the ability to project lines and dots on multiple surfaces. This temporal separation of laser operations resolves the contradiction between multi-surface functionality and excessive intersection intensity.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent implements dynamics by making the laser module activation patterns adjustable and controllable through PWM duty cycles. The system can dynamically adjust which modules are active and for how long, allowing optimization of both productivity and intensity management. This dynamic control enables the system to adapt between different operational modes (e.g., single surface vs. multiple surfaces, different line configurations) while managing intersection point intensity.

Inventive Principle:
Principle #15Dynamics

2Illumination intensity

If laser beam intensity is increased for better visibility, then illumination intensity is improved, but safety and measurement precision deteriorate due to excessive brightness at intersection points

Engineering Contradiction:
Improvelaser beam visibilityVSAvoidaccuracy of construction layout tasks
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

By using periodic PWM activation of laser modules, the system maintains high visibility during each active period while preventing continuous overexposure at intersection points. The time-multiplexed operation ensures that no single intersection point receives cumulative intensity exceeding safe thresholds, thereby preserving measurement precision for construction layout tasks while still providing adequate beam visibility.

Inventive Principle:
Principle #19Periodic action

3Illumination intensity

If all laser modules operate at full power simultaneously, then illumination intensity is maximized, but the system exceeds maximum allowable intensity at intersection points

Engineering Contradiction:
Improveoverall laser beam brightnessVSAvoidexcessive intensity at intersection points
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent uses periodic PWM control to manage the operation of multiple laser modules. Instead of all modules running at full power simultaneously, they are activated in staggered time sequences with controlled duty cycles. This ensures that the cumulative intensity at any intersection point remains below maximum allowable thresholds while each module still operates at full power during its active period, maintaining overall illumination quality without exceeding safety limits.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system applies parameter changes by adjusting the PWM duty cycle percentages for each laser module based on operational conditions. When multiple modules need to operate, their individual duty cycles are reduced or staggered to keep intersection intensity within limits. This dynamic parameter adjustment allows the system to optimize between overall illumination intensity and intersection point intensity constraints.

Inventive Principle:
Principle #35Parameter changes

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 maintains the intensity of laser beams at intersection points at or below 140% of a single beam's intensity, preventing excessive brightness and ensuring accurate projection for construction layout tasks.

Implementation Method 1

A first laser diode 32, a second laser diode 52 and a third laser diode 62 are disposed in the cavity

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

The individual diodes 32, 52, 62 can be turned on and off independently

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 3

The gimbal assembly 26 is rotatable by gravity so that it levels the laser modules 20

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP3526543B1Power tool
Publication Date: 2024.02.28 STANLEY BLACK & DECKER INC
  • EP3526543B1 patent drawingFigure 1
  • EP3526543B1 patent drawingFigure 2
  • EP3526543B1 patent drawingFigure 3

AI summary

A laser beam generating device (10) includes a housing (11) a first laser diode (32) which generates a visible first output beam which projects outside of the housing (11) onto a surface and a second laser diode (42) which generates a visible second output beam which projects outside of the housing (11) onto the surface. The laser beam generating device (10) has a first mode in which the first laser diode (32) and the second laser diode (42) are both on. In the first mode, the first laser diode (32) is operated at a first duty cycle and the second laser diode (42) is operated at a second duty cycle. The first duty cycle and the second duty cycle are staggered.