Method for improving the start up of an ultrasonic system under zero load conditions
US6898536B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 4, 2002 |
| Grant date | May 24, 2005 |
| Priority date | — |
| Expiry date | Feb 26, 2023 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB06B2201/76
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
The start up performance of an ultrasonic system under zero load conditions is improved by setting a phase set point in a frequency control loop such that, at start up under zero load conditions, the phase set point intersects a point on a phase-frequency response curve which has a low positive slope. This intersection point on the phase-frequency response curve changes as the load is increased and the system Q is decreased. The controller “seeks” a target 0° impedance phase angle. The frequency of the ultrasonic generator is set to an off-resonance frequency which is lower than the resonance of any known hand piece/blade combination. In order for the drive voltage to not exceed the physical limit of the system, the drive current is set to a low level. The drive frequency is then smoothly increased in steps until the target 0° impedance phase delta is located.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.