초록 ▼

The actual resonant frequency of an ultrasonic horn is tracked actively while the horn is operating in a working environment, such as in a clinical analyzer where the horn is partly immersed in a liquid bath in which a series of liquid-filled cuvettes are passed near the horn to dissolve solid table

The actual resonant frequency of an ultrasonic horn is tracked actively while the horn is operating in a working environment, such as in a clinical analyzer where the horn is partly immersed in a liquid bath in which a series of liquid-filled cuvettes are passed near the horn to dissolve solid tablets in the cuvettes. The horn is driven initially by a signal of fixed amplitude but at a frequency which is varied between set limits about a nominal resonant frequency. Ultrasonic vibration waves of the horn are sensed and fed back for rectification and peak detection over the scan operation. The peak feed back level is held and a second scan is initiated with the drive signal at the same fixed amplitude. When the rectified feedback signal level substantially attains that of the held peak level, a comparison is determined and control logic acts to lock on the frequency at which the comparison was established for a given operating time period.

대표청구항 ▼

Apparatus for driving an ultrasonic horn at a resonant frequency actively determined during operation of the horn under varying load conditions, comprising: frequency scanning and drive means for driving an ultrasonic horn with a drive signal of determined amplitude and frequency; feedback means in

Apparatus for driving an ultrasonic horn at a resonant frequency actively determined during operation of the horn under varying load conditions, comprising: frequency scanning and drive means for driving an ultrasonic horn with a drive signal of determined amplitude and frequency; feedback means in the vicinity of the horn for sensing ultrasonic vibration waves from the horn in an operating environment when driven by said frequency scanning and drive means, and for producing an output signal corresponding to the frequency and amplitude of said ultrasonic waves; rectifier means for detecting the output signal of said feedback means and for developing a direct current amplitude signal representative of the amplitude of said output signal; peak detector means coupled to said rectifier means for developing a peak signal corresponding to the maximum level of said amplitude signal attained during a first scan of said frequency scanning and drive means, wherein said drive signal is at a fixed amplitude but is varied in frequency between limits about a nominal frequency; comparator means coupled to said rectifier means and said peak detector means for comparing said amplitude signal and said peak signal with one another over a second scan of said frequency scanning and drive means between said frequency limits with said fixed amplitude drive signal, and for producing a match signal indicative of a resonant condition for said horn when said amplitude and said peak signals are substantially equal; and control means coupled to said comparator means and said frequency scanning and drive means for controlling said first and said second scan operations and interrupting said second scan in response to said match signal, and for enabling said scanning and drive means to continue to operate the horn at a frequency corresponding to said resonant condition for a given time period.