Patent US3842340A successfully refreshed from Google Patents.
US3842340A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Generator for producing ultrasonic oscillations
Assignee: US Philips Corp
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Filing: 1970-02-16
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Granted: 1974-10-15
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Expires: 1990-02-16
Abstract
Abstract An ultrasonic generator with means for automatically adjusting the oscillation frequency to provide maximum power to the load. The generator includes a DC-AC converter operating into a resonant circuit that is coupled to the transducer. The converter includes first and second switching devices alternately switched by the frequency modulated output of a frequency controllable oscillator. The modulation frequency is derived across a resistor in the converter circuit and is compared with the modulation frequency in a phase detector to produce a control signal whose polarity is determined by the phase relationship of the compared signals. This control signal controls the oscillator to a frequency at which the transducer delivers maximum power to a load.
Inventors
- 👤 R Brandquist
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:23
CPC Classifications
B; B06; B06B; B06B1/00; B06B1/02; B06B1/0207; B06B1/0223; B06B1/0238; B06B1/0246; B06B1/0253; B06B2201/00; B06B2201/70; B06B2201/71
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
188 words
A generator for producing ultrasonic oscillations, comprising a resonant circuit and a transducer coupled thereto to receive the output energy thereof, a direct current source coupled in circuit to two switching devices controlled by means of a controllable oscillator so as to convert the DC current into an alternating current, means for applying said alternating current to said resonant circuit, means connected to said switching devices and to said controllable oscillator for modulating said alternating current, a comparison device connected to said modulating means and to a parallel resistor included in the alternating current circuit, said resistor deriving a signal that exhibits an amplitude response to the frequency variations which determines the sign of the derivative of the current with respect to the current frequency, said comparison device providing an output signal whose polarity is determined by the phase relationship between the signal derived across the resistor and the signal received from said modulating means, and means for applying said output signal as a control signal to said controllable oscillator thereby to vary the frequency thereof in a direction tending to optimize the energy transfer to the transducer.
Claim 2
Dependent Claim
188 words
A generator for producing ultrasonic oscillations, comprising a resonant circuit and a transducer coupled thereto to receive the output energy thereof, a direct current source coupled in circuit to two switching devices controlled by means of a controllable oscillator so as to convert the DC current into an alternating current, means for applying said alternating current to said resonant circuit, means connected to said switching devices and to said controllable oscillator for modulating said alternating current, a comparison device connected to said modulating means and to a parallel resistor included in the alternating current circuit, said resistor deriving a signal that exhibits an amplitude response to the frequency variations which determines the sign of the derivative of the current with respect to the current frequency, said comparison device providing an output signal whose polarity is determined by the phase relationship between the signal derived across the resistor and the signal received from said modulating means, and means for applying said output signal as a control signal to said controllable oscillator thereby to vary the frequency thereof in a direction tending to optimize the energy transfer to the transducer.
Claim 3
Dependent Claim
113 words
A generator as claimed in claim 1 wherein said modulating means comprises a signal generator and a modulator, the output signal from the controllable oscillator being frequency modulated in said modulator by the output signal from the signal generator, and wherein said comparison device comprises a phase sensitive detector one input circuit of which is connected to the alternating current circuit and includes a lowpass filter for selecting the modulation signal component from said alternating current, means connecting the other input circuit of said detector to the output of the signal generator, and means connecting the output of said phase sensitive detector to said controllable oscillator to supply said output control signal thereto.
Claim 4
Dependent Claim
43 words
A generator as claimed in claim 2 wherein said resonant circuit is tuned to the nominal operating frequency of the controllable oscillator and said signal generator supplies a signal of a frequency that is lower than the operating frequency of the controllable oscillator.
Claim 5
Dependent Claim
160 words
An ultrasonic generator comprising, a source of DC current coupled to a DC to AC converter circuit that includes a resonant circuit, a resistor, and at least two controlled switching devices each with a control electrode coupled to the output of a frequency controllable oscillator, a transducer coupled to said resonant circuit, means interposed betWeen the output of said oscillator and said control electrodes for modulating the output signal of the oscillator at a lower frequency than the oscillator frequency to produce across said resistor an amplitude response to the frequency variations with a signal component at said lower frequency, means coupled to said resistor for deriving an error control signal whose polarity is determined by the phase relationship of said signal component relative to the lower frequency modulating signal, and means for applying said control signal to the control input of said oscillator so as to vary the frequency thereof in a sense tending to null the error signal.
Claim 6
Dependent Claim
160 words
An ultrasonic generator comprising, a source of DC current coupled to a DC to AC converter circuit that includes a resonant circuit, a resistor, and at least two controlled switching devices each with a control electrode coupled to the output of a frequency controllable oscillator, a transducer coupled to said resonant circuit, means interposed betWeen the output of said oscillator and said control electrodes for modulating the output signal of the oscillator at a lower frequency than the oscillator frequency to produce across said resistor an amplitude response to the frequency variations with a signal component at said lower frequency, means coupled to said resistor for deriving an error control signal whose polarity is determined by the phase relationship of said signal component relative to the lower frequency modulating signal, and means for applying said control signal to the control input of said oscillator so as to vary the frequency thereof in a sense tending to null the error signal.
Claim 7
Dependent Claim
101 words
An ultrasonic generator as claimed in claim 4 wherein said error signal deriving means comprises a phase detector with a first input coupled to said resistor and a second input coupled to said signal modulating means to receive the modulation signal of said lower frequency, said phase detector producing an error signal of one polarity when the compared input signals thereto are in phase and of the opposite polarity when the compared input signals are in phase opposition, the frequency of said oscillator being either increased or decreased until the amplitude response of the circuit to the modulation frequency is zero.
Claim 8
Dependent Claim
43 words
An ultrasonic generator as claimed in claim 5 further comprising a filter connected between said resistor and said first input of the detector and tuned to pass signals of said lower frequency and to block the passage of signals of the oscillator frequency.
Claim 9
Dependent Claim
65 words
An ultrasonic generator as claimed in claim 5 wherein said signal modulating means comprises, a modulator having one input coupled to the output of the oscillator and an output coupled to the control electrodes of said switching devices, and a signal generator supplying a signal of said lower frequency to a second input of the modulator and to said second input of the phase detector.
Claim 10
Dependent Claim
22 words
An ultrasonic generator as claimed in claim 4 wherein said resonant circuit is tuned to the operating frequency of the controllable oscillator.
Claim 11
Dependent Claim
96 words
An ultrasonic generator as claimed in claim 8 wherein said resonant circuit comprises a transformer with a secondary winding coupled to the transducer and a primary winding coupled to said switching devices to form first and second series circuits across the DC source that includes said resistor in common and a first part of the primary winding and one switching device in the first series circuit and a second part of the primary winding and a second switching device in the second series circuit, and a capacitor connected in parallel with one of said transformer windings.
Claim 12
Dependent Claim
59 words
An ultrasonic generator as claimed in claim 9 further comprising an inductor connected in series in common with each of said first and second series circuits across the DC source, said inductor having an inductance that is much larger than the inductance of said primary winding, and first and second diodes individually connected in series with said switching means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |