LED Series Current Limiting Circuit for Peak Overcurrent Isolation

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Solution Overview

Problem

Existing light source devices using LEDs connected in series face issues with instantaneous peak currents due to time-lags in detecting and controlling current changes, leading to overcurrent and potential failures in normal light-emitting elements.

Innovation Solution

Incorporating a peak current limiting circuit with a current detector consisting of a resistor and a coil, which induces a peak voltage to control the current instantly, reducing the duration of peak current flow to protect other elements from overcurrent.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a laser beam is focused to a small spot size to achieve high processing precision, then manufacturing precision is improved, but the beam diameter becomes smaller which limits the available power and processing speed

Engineering Contradiction:
Improveprocessing precisionVSAvoidbeam diameter
Core Design Contradiction:
Manufacturing precisionVSLength of moving object

Solution Approach 1:

The patent divides the laser beam into multiple separate beams using beam splitting elements (such as beam splitting mirrors or prisms). Each beam can be independently focused to a small spot size for high precision processing, while the total power is distributed across multiple beams. This segmentation allows simultaneous achievement of small spot size and sufficient power by processing multiple locations or by combining the effects of multiple focused beams.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extends the processing from a single focal point to multiple focal points arranged in specific spatial patterns (such as arrays or grids). By distributing the focused beams in the transverse plane, the system achieves high precision at each point while maintaining overall processing capability through parallel operation or sequential scanning of multiple locations.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If the laser beam diameter is increased to improve processing speed and power delivery, then productivity is improved, but the manufacturing precision and spot size control deteriorate

Engineering Contradiction:
Improveprocessing speedVSAvoidspot size control
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

By splitting the high-power laser beam into multiple lower-power beams, each beam can be tightly focused to a small spot size for precision processing. The overall processing speed is maintained or enhanced through parallel processing of multiple spots or through efficient scanning patterns that utilize the distributed beam arrangement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines multiple focused beams to process a workpiece simultaneously at multiple locations. The effects of individual beams are merged to achieve overall high productivity while each beam maintains small spot size for precision. The combined processing action of multiple beams equals or exceeds the productivity of a single high-power beam while maintaining superior precision.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If uniform beam intensity distribution is used to simplify processing, then ease of operation is improved, but manufacturing precision deteriorates due to insufficient peak power density

Engineering Contradiction:
Improveprocessing simplicityVSAvoidcutting precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent creates different intensity distributions for different parts of the beam profile or for different beams in the array. Each beam or region can be optimized with appropriate intensity concentration to achieve the required peak power density for precision processing, while the overall system remains relatively simple to operate through standardized beam generation and positioning procedures.

Inventive Principle:
Principle #3Local quality

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 limits peak currents to prevent failures in light-emitting elements, ensuring a stable constant current flow even when one element fails, thus protecting the entire series connection.

Implementation Method 1

an optical system which focuses a laser beam to a small spot size on a workpiece

Methodology Applied
Scientific EffectOptical focusing: Focusing

Implementation Method 2

irradiating a workpiece with the laser beam

Methodology Applied
Scientific EffectOptical to thermal energy conversion: Absorption (EM radiation)

Data Source

PatentEP4080995B1Light source device
Publication Date: 2026.04.08 NICHIA CORP
  • EP4080995B1 patent drawingFigure 1
  • EP4080995B1 patent drawingFigure 2
  • EP4080995B1 patent drawingFigure 3

AI summary

[Problem to be Solved] Provided is a light source device in which light-emitting output can be increased by simultaneously turning on a plurality of light-emitting elements, and occurrence of a failure in any of light-emitting elements can be prevented from having an effect on other light-emitting elements. [Solution] A light source device of the present disclosure supplies a constant current to a diode load 10 that includes a plurality of light-emitting elements 1 connected in series. The light source device includes a power supply circuit 20 connected to the diode load 10 and a peak current limiting circuit 30 connected in series to the diode load 10. The peak current limiting circuit 30 includes a current detector 31 that is connected in series to the diode load 10 and a current-regulating circuit 32 that controls a current to the diode load 10 by a detection voltage of the current detector 31. Further, the current detector 31 comprises a series circuit including a resistor 4 and a coil 5.