Micromirror Actuator Assembly with Dual PCB and Spacer

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Solution Overview

Problem

Micromirror actuator assemblies face challenges in controlling the movement of micromirrors without straining surrounding components, leading to deformation of printed circuit boards (PCBs), audible noise, and reduced precision due to unconfined kinetic energy, which existing solutions like increasing PCB thickness or material rigidity may not adequately address.

Innovation Solution

The implementation of a dual-PCB micromirror actuator assembly with a flexible frame and additional spacers, where the micromirror is sandwiched between a lower and upper PCB, and optionally a deformation-resistant supporting cover, to reduce deformation of the lower PCB during scanning by providing additional rigidity and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the PCB thickness is increased or material rigidity is enhanced to reduce deformation during micromirror scanning, then the structural stability improves, but the device complexity and cost increase

Engineering Contradiction:
ImprovePCB structural stabilityVSAvoiddevice complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The PCB is divided into two separate boards: a lower PCB that undergoes deformation during micromirror scanning and an upper PCB that remains rigid and stable. This segmentation allows each PCB to be optimized independently for its specific function, avoiding the need to make the entire PCB structure overly rigid or thick.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A spacer component is introduced as an intermediary element between the lower PCB and the upper PCB. The spacer provides mechanical support and maintains the relative positioning between the two PCBs, enabling the lower PCB to deform freely while the upper PCB remains stable, thus solving the structural stability issue without increasing overall device complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If additional supporting elements are added to reduce PCB deformation during scanning, then the micromirror control precision improves, but the device complexity increases

Engineering Contradiction:
Improvemicromirror control precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The support structure is segmented into two functional parts: the lower PCB that allows controlled deformation for micromirror scanning and the upper PCB that provides rigid support. This segmentation enables precise micromirror control by isolating the deformation to only the lower PCB, maintaining control precision without adding complex support mechanisms throughout the entire structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spacer acts as an intermediary support element that provides mechanical reinforcement to the lower PCB during scanning without interfering with the micromirror's movement. This intermediary structure enhances micromirror control precision by stabilizing the supporting structure while allowing the lower PCB to deform controllably, avoiding the need for complex active control mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Weight of moving object

If the PCB is made thinner to reduce weight and cost, then the device becomes more compact and cost-effective, but the PCB deformation increases during scanning

Engineering Contradiction:
ImprovePCB weightVSAvoidPCB deformation control
Core Design Contradiction:
Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The PCB system is segmented into a lower thin PCB that is acceptable to deform during scanning and an upper thicker PCB that provides structural stability. This allows the lower PCB to be made thinner, reducing overall weight and cost, while the upper PCB compensates for any deformation issues, maintaining stability where needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spacer serves as an intermediary structural element that compensates for the thinness of the lower PCB during scanning. It provides the necessary mechanical support to prevent excessive deformation while allowing the lower PCB to remain thin, thus achieving both weight reduction and deformation control without requiring the entire PCB structure to be thick and heavy.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 configuration effectively reduces deformation of the lower PCB, enhances micromirror control, and maintains a compact and cost-effective design by using thinner PCBs and strategically positioned spacers, while also providing protection during handling and assembly.

Implementation Method 1

a first actuator, such as a piezoelectric actuator, affixed to the frame and configured to selectively tilt the micromirror

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

Desired movement of the micromirror may be induced via selective bending of a flexible frame that supports the micromirror

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3844548B1Micromirror actuator assembly
Publication Date: 2023.09.20 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3844548B1 patent drawingFigure 1
  • EP3844548B1 patent drawingFigure 2
  • EP3844548B1 patent drawingFigure 3

AI summary

A micromirror actuator assembly (100) includes a lower printed circuit board (PCB) (102), an upper PCB (104), and a frame (106) spaced away from the lower PCB and spaced away from the upper PCB between the lower PCB and the upper PCB. A micromirror (112) is rotatably attached to the frame. A plurality of piezoelectric actuators (116A, 116B) are affixed to the frame and configured to selectively deform the frame to scan the micromirror.