DMD Chip Mounting in Vehicle Headlamps

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Solution Overview

Problem

The existing method for mounting a DMD chip in a motor vehicle headlight light module is not accurate enough, leading to undesirably tilted light distributions due to positional tolerances, which can result in oblique light-dark lines instead of parallel lines, affecting the light distribution's shape and clarity.

Innovation Solution

The method involves aligning the printed circuit board (PCB) with the DMD chip using an elastic connecting element to compensate for positional tolerances, ensuring the PCB is clamped without transmitting holding forces in the z-direction, and using adhesive bonds and screw tightening to secure the PCB to the central carrier element, with the elastic element generating a restoring force to maintain contact pressure within a defined range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a pin-and-slot structure is used for mounting the DMD chip, then the assembly is simple to manufacture, but the positioning precision is insufficient leading to tilted light distributions

Engineering Contradiction:
Improvepositioning precisionVSAvoidmounting structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a printed circuit board (PCB) as an intermediary component between the mounting structure and the DMD chip. The PCB provides a stable platform with integrated positioning features that achieve high positioning precision without requiring complex direct mounting structures. The PCB acts as a mediator that translates simple mounting operations into precise chip positioning.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the PCB transmits holding forces in the z-direction, then the DMD chip is securely held, but the PCB vibrates during operation subject to vibration

Engineering Contradiction:
Improveholding stabilityVSAvoidPCB vibration stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent extracts the vibration-prone force transmission function from the PCB by introducing dedicated support elements that handle z-direction holding forces. This separation allows the PCB to focus on its primary functions (electrical connections and planar positioning) while the specialized support elements manage vertical stabilization, reducing PCB vibration during operation.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If excessive clamping forces are applied to the DMD chip, then the chip is securely fixed, but the chip may be damaged

Engineering Contradiction:
Improvefixing reliabilityVSAvoidchip damage risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs elastic support elements that automatically adjust the clamping force parameters through elastic deformation. The elasticity provides a self-regulating mechanism where the force adapts to the chip's requirements, ensuring sufficient fixing reliability while preventing excessive forces that could cause damage. This dynamic parameter adjustment eliminates the need for precise force control during assembly.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If the DMD chip position is not precisely aligned, then the assembly process is faster, but the light distribution becomes tilted with slanted cut-off lines

Engineering Contradiction:
Improveassembly speedVSAvoidlight distribution accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements preliminary alignment features directly integrated into the PCB and support elements during the manufacturing stage. These pre-configured positioning structures eliminate the need for time-consuming post-assembly adjustments, enabling both fast assembly and high precision light distribution alignment to be achieved simultaneously through advance preparation of the mounting infrastructure.

Inventive Principle:
Principle #10Preliminary 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 prevents the PCB from swinging and ensures accurate light distribution by compensating for positional tolerances, maintaining contact pressure within safe limits to prevent damage, and providing a stable and reliable mounting solution for the DMD chip.

Implementation Method 1

The clamping force is generated by an elastic connecting element of the clamping element assembly as a restoring force of an elastic deformation that the elastic connecting element experiences during the assembly of the light module

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the fixing is carried out by adhesive bonds

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3578875B1Method of mounting and adjusting a dmd chip in a light module for a motor vehicle headlamp
Publication Date: 2023.03.08 MARELLI GERMANY GMBH
  • EP3578875B1 patent drawingFigure 1
  • EP3578875B1 patent drawingFigure 2
  • EP3578875B1 patent drawingFigure 3

AI summary

A method for mounting a circuit board carrying a DMD chip in a DMD light module for a motor vehicle headlight is presented.The method is characterized by the following steps: manufacturing a sub-module of the light module, wherein the central support element is elastically connected to the clamping element assembly and wherein the DMD chip is clamped between the support element and the clamping element; establishing a reference system by inserting the sub-module into an alignment device, which has a gripper movable by an actuator, an image signal-generating camera, and a control unit that processes image signals from the camera into control signals for the actuator; controlling the position of the gripper depending on a deviation of the position of the DMD chip from a target position so that the DMD chip assumes the target position; and fixing the DMD chip in the central support element when the target position is reached.