Vibrator Drive Control Circuit for Moisture-Induced Holding Force Loss
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Solution Overview
Problem
Vibration-type actuators experience a decrease in holding force due to moisture and humidity, leading to misalignment issues when idle for a long time or used in high-humidity environments, as the frictional force between the vibrator and driven body is reduced.
Innovation Solution
A drive control circuit that generates an elliptical motion with a component parallel to the driving direction, utilizing a control unit to output an alternating-current signal to the electro-mechanical energy conversion element, which removes moisture through frictional energy generation, thereby restoring the holding torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vibrator and driven body are left stationary for a long time or used in high-humidity environment, then moisture accumulates on the frictional sliding surfaces, but holding force decreases due to reduced friction
Solution Approach 1:
The patent applies periodic vibration to the vibrator at specific intervals (when stationary for long periods or in high-humidity environments). This periodic action generates frictional heat that removes accumulated moisture from the contact surfaces, restoring holding force without requiring continuous vibration or additional mechanical components.
Solution Approach 2:
The patent utilizes mechanical vibration of the vibrator to generate frictional energy at the contact surfaces with the driven body. By controlling the vibration characteristics (amplitude, frequency, duration), the system generates sufficient heat to evaporate moisture while maintaining positional stability during normal operation.
2Reliability
If additional mechanisms are added to maintain positional relationship, then holding force stability improves, but device complexity increases
Solution Approach 1:
The patent employs the vibrator's own vibration function to restore holding force rather than adding separate positioning mechanisms. The same electro-mechanical energy conversion element that drives the system is used to generate frictional heat for moisture removal, eliminating the need for additional actuators, sensors, or control mechanisms.
Solution Approach 2:
The vibrator serves dual functions: (1) generating driving force through elliptical motion during normal operation, and (2) restoring holding force by generating frictional heat when moisture accumulates. This multi-functionality eliminates the need for dedicated moisture removal mechanisms or additional positioning systems.
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
The solution effectively restores holding torque and prevents misalignment by generating frictional energy on the contact surfaces, even in high-humidity conditions or after a long period of inactivity, ensuring reliable operation of the vibration-type actuator.
Implementation Method 1
a piezoelectric element, which is an electro-mechanical energy conversion element, is bonded to a first side of a plate-like elastic body
Implementation Method 2
frictional energy is generated to remove moisture existing on frictional sliding surfaces of the vibrator and the driven body
Data Source
AI summary
A drive control circuit restores a holding force when a vibrator and a driven body have been left at a standstill for a long time period and when they are used in a high-humidity environment. A drive circuit outputs an alternating-current signal, which is to be applied to an electro-mechanical energy conversion element, based on an output from a control unit. The control circuit controls the drive circuit with first timing such that elliptical motion produced in the vibrator takes a path of which a component parallel to a driving direction of the driven body is large as compared to such a path that a speed at which the driven body is driven is the maximum. The first timing is different from second timing with which relative positions of the vibrator and the driven body are changed.