Analog drive for ultrasonic probe with tunable phase angle
US4970656A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 20, 1989 |
| Grant date | Nov 13, 1990 |
| Priority date | — |
| Expiry date | Oct 20, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB06B2201/55
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
The system uses a tunable inductor in series with the piezoelectric crystal excitation transducer in the probe which has a flux modulation coil. The bias current through this flux modulation coil is controlled by the system. It is controlled such that the inductance of the tunable inductor cancels out the capacitive reactance of the load impedance presented by the probe when the probe is being driven by a driving signal which matches the mechanical resonance frequency of the probe. The resulting overall load impedance is substantially purely resistive. The system measures the phase angle and monitors the power level. The system uses this information to adjust the bias current flowing through the flux modulation coil to maintain the substantially purely resistive load impedance for changing power levels. This information is also used to adjust the frequency of the driving signal to track changing mechanical resonance conditions for the probe at different power levels. This method of operation insures substantially maximum power transfer efficiency and substantially linear power control over a range of power dissipation levels. There is also disclosed an analog circuit to measure the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.