Piezoelectric Actuator Layout for Accurate Motion Detection
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Solution Overview
Problem
In actuator devices with piezoelectric drive and detection bodies on opposite surfaces of a metal substrate, variations in the relative positional relationship between these components lead to inaccuracies in detecting the operation amount of a movable portion, necessitating complex signal subtraction to account for phase differences.
Innovation Solution
The actuator device includes a configuration where piezoelectric drive and detection bodies are positioned with aligned centers and separated by bonding members to maintain a fixed relative position, with electrical connections to a reference potential, ensuring accurate detection of the movable portion's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If piezoelectric drive body and detection body are disposed on opposite main surfaces of metal substrate, then structural support is improved, but relative positional variation occurs leading to detection accuracy degradation
Solution Approach 1:
A resin layer is introduced as an intermediary between the piezoelectric drive body and metal substrate, and between the piezoelectric detection body and metal substrate. This resin layer acts as a bonding mediator that maintains fixed relative positions while allowing the piezoelectric bodies to be disposed on opposite surfaces, thus resolving the contradiction between structural support and positional stability.
Solution Approach 2:
The patent specifies controlling the thickness of the resin layer to be 0.01 mm or more and 0.5 mm or less, and controlling the distance between piezoelectric bodies to be 1 mm or more and 5 mm or less. By optimizing these dimensional parameters, the patent achieves both structural support from opposite-surface disposition and minimal positional variation for accurate detection.
2Measurement precision
If piezoelectric drive body and detection body are disposed on same main surface of metal substrate, then relative positional stability is improved, but device complexity increases due to wiring and signal routing
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement (both piezoelectric bodies on the same surface) to a three-dimensional arrangement (piezoelectric bodies on opposite surfaces bonded through the substrate thickness). This dimensional change allows both bodies to maintain stable relative positions while simplifying wiring by utilizing the thickness direction for signal routing through the substrate.
3Volume of moving object
If piezoelectric drive body and detection body are closely positioned, then device size is reduced, but phase difference between signals increases leading to detection accuracy degradation
Solution Approach 1:
The patent optimizes the distance between piezoelectric drive body and detection body to be 1 mm or more and 5 mm or less, and controls the resin layer thickness to be 0.01 mm or more and 0.5 mm or less. These parameter optimizations achieve compact device size while maintaining sufficient separation to minimize phase difference and ensure accurate detection.
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 enables precise detection of the movable portion's operation by minimizing phase differences and enhancing accuracy, thereby improving the actuator's performance.
Implementation Method 1
a piezoelectric drive body disposed on one main surface of the metal substrate; and a piezoelectric detection body disposed on the other main surface of the metal substrate
Data Source
AI summary
An actuator device includes a wiring substrate; a metal substrate; a first electrode unit provided to the metal substrate; a piezoelectric drive body disposed on the first electrode unit; a second electrode unit disposed on a first main surface of the piezoelectric drive body; a piezoelectric detection body disposed on the second electrode unit; a third electrode unit disposed on a third main surface of the piezoelectric detection body; a connection unit; an input unit; and an output unit. The connection unit is configured to be electrically connected to a reference potential on an outside such that a potential of the second electrode unit becomes the reference potential. The input unit is configured to input a drive signal to the first electrode unit from the outside. The output unit is configured to output an output signal generated in the piezoelectric detection body, to the outside from the third electrode unit.