Integrated DAC Control for Micromechanical Actuators With Low Interference

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Solution Overview

Problem

Existing micromechanical actuators in devices like spatial light modulators face issues with increased susceptibility to interference, limited bandwidth, and high power dissipation due to parasitic loads, which hinder a compact and efficient design.

Innovation Solution

Implementing a digital interface with integrated digital-to-analog converters on the SLM chip, incorporating the column line capacitance into capacitive voltage dividers, and eliminating operational amplifiers to reduce power dissipation and interference, while maintaining precision and speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an analog interface is used to transmit address voltages to micromechanical actuators, then the actuators can be controlled precisely, but the system becomes more susceptible to interference and consumes more power due to parasitic loads

Engineering Contradiction:
Improvecontrol precisionVSAvoidinterference susceptibility
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the analog interface with a digital interface, substituting the continuous voltage signal transmission with discrete digital signal transmission. This eliminates the analog signal path that is susceptible to interference while maintaining control precision through digital-to-analog conversion integrated on the same substrate.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the digital-to-analog conversion function from the external control circuit and integrates it directly onto the SLM chip substrate. This removes the need for external analog signal transmission and eliminates the parasitic loads associated with external analog interfaces.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of operation

If an analog interface with external control circuit is used, then the actuators can be controlled, but the overall system design becomes less compact due to large parasitic loads

Engineering Contradiction:
Improveactuator controlVSAvoidsystem compactness
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges the control circuit and the SLM chip into a single integrated structure on the same substrate. The digital-to-analog converter is integrated directly on the SLM chip, eliminating separate external components and reducing overall system complexity while maintaining actuator control functionality.

Inventive Principle:
Principle #5Merging (Combining)

3Power

If the control circuit applies full address voltage to parasitic loads, then the actuators receive sufficient voltage, but power dissipation increases significantly

Engineering Contradiction:
Improvevoltage deliveryVSAvoidpower dissipation
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent substitutes the analog voltage delivery system with a digital signal system that consumes less power. The integrated digital-to-analog converter on the same substrate eliminates the need to drive high-voltage signals through external parasitic loads, significantly reducing power dissipation while maintaining adequate voltage delivery to actuators.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of operation

If analog switches and external control circuits are used, then the actuators can be addressed, but the bandwidth of the analog lines is limited

Engineering Contradiction:
Improveactuator addressingVSAvoidbandwidth
Core Design Contradiction:
Ease of operationVSSpeed

Solution Approach 1:

The patent replaces the analog switching and signal transmission system with a digital signal system. Digital signals have inherently wider bandwidth and faster transmission speeds compared to analog signals, enabling higher frame rates and faster actuator addressing while maintaining the ability to address all actuators in the array.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Achieves a compact, low-loss, and interference-resistant system design with reduced power consumption, enabling precise control of micromechanical actuators at high frame rates.

Implementation Method 1

a digital-to-analog converter (DAC) which provides a voltage to be applied to the connecting structure by an adjustable capacitive voltage division which is dependent on a digital input value of the digital-to-analog converter

Methodology Applied
Scientific EffectCapacitive voltage division: Capacitance

Implementation Method 2

This is achieved, for example, by a balance between electrostatic or electromagnetic forces on the one hand and restoring spring forces on the other

Methodology Applied
Scientific EffectElectrostatic force: Electrostatics

Implementation Method 3

This is achieved, for example, by a balance between electrostatic or electromagnetic forces on the one hand and restoring spring forces on the other

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentEP3850614B1Micromechanial actuators with integrated digital-to-analog converters, method and computer program
Publication Date: 2025.07.09 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3850614B1 patent drawingFigure 1
  • EP3850614B1 patent drawingFigure 2
  • EP3850614B1 patent drawingFigure 3

AI summary

An arrangement for controlling micromechanical actuators, comprising a digital-to-analog converter and a plurality of micromechanical actuators; wherein: the micromechanical actuators are coupled to a connecting structure; the digital-to-analog converter is designed to provide a voltage that can be applied to the connecting structure, by a selectable capacitive voltage division that is dependent on a digital input value of the digital-to-analog converter; and the digital-to-analog converter is designed to directly integrate the capacity of the connecting structure (Ccol) into the capacitive voltage division.