Vibration Actuator Encoder Layout for Backlash-Resistant Position Detection
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Solution Overview
Problem
Vibration type actuators face challenges in accurately detecting relative movement between the vibrating body and the contact body due to backlash or misalignment, leading to reduced positioning accuracy and unstable driving.
Innovation Solution
The actuator incorporates a vibrating body with protrusion portions and a contact body, supported by a holding unit and a support unit with guide portions and guide receiving portions, along with a position detection unit fixed to overlap with the guide receiving portions, ensuring precise alignment and detection of relative positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an encoder main body and a scale are attached to detect relative movement, then positioning capability is provided, but backlash or misalignment causes the encoder main body to move relative to the scale, reducing measurement precision
Solution Approach 1:
The patent introduces guide portions and guide receiving portions as intermediary elements that mediate between the support unit and holding unit. These guide structures constrain relative movement directions and reduce the impact of backlash, allowing the encoder to accurately detect only the intended vibrational movement rather than spurious movements from loose connections.
Solution Approach 2:
The patent creates a stable reference frame by fixing the encoder main body to the support unit and the scale to the holding unit in a manner that eliminates differential movement caused by backlash. The guide portions ensure both components operate from stable, aligned reference positions, making the measurement system equipotential and accurate.
2Stability of the object's composition
If guide portions and guide receiving portions are provided to constrain relative movement, then alignment stability is improved, but device complexity increases
Solution Approach 1:
The patent divides the support and holding units into distinct segments with dedicated guide portions and guide receiving portions. This segmentation allows each component to have a specific function - the guide portions constrain movement in one direction while allowing vibration in another, providing stability without requiring complete rigidification of the entire structure.
Solution Approach 2:
The patent applies guidance and constraint features only at specific locations where needed - the guide portions are provided on one unit while guide receiving portions are provided on the other unit at corresponding positions. This localized application of structural features provides necessary stability without adding complexity throughout the entire device.
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 enhances the actuator's positioning accuracy by minimizing the impact of backlash and misalignment, allowing for stable and accurate driving.
Implementation Method 1
a vibrating body that includes an electrical-mechanical energy conversion element
Implementation Method 2
a vibration type actuator obtains a driving force by bringing a vibrating body and a driven body into pressure contact and frictionally driving the vibrating body and the driven body relative to each other using vibration excited in the vibrating body
Data Source
AI summary
In a vibration type actuator according to the present invention, a lower support member includes a pair of guide portions that guide a relative position of a holding member and the lower support member in a second direction, and the holding member includes a pair of guide receiving portions that are guided by the pair of guide portions. An encoder main body is fixed to the lower support member at a position overlapping with an area sandwiched between the pair of guide receiving portions as viewed from the second direction.