Browse Prior Art Database

Ultrasonic Welding/Real Power Monitor

IP.com Disclosure Number: IPCOM000076805D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Aujla, PS: AUTHOR [+3]

Abstract

The circuit of the drawing measures the power applied to an ultrasonic bonder and the load on the bonder tip. The bonder is represented schematically by a signal source 2, a source impedance 3, and a load impedance 4. The voltage e that appears across load 4 is a component of the power applied to the load. A resistor 5 of low-resistance value is connected in the circuit to produce a voltage el that is proportional to the load current. Operational amplifiers 7 and 8 apply these voltages to a multiplier circuit 9 that produces an output eel, which signifies the instantaneous value of power applied to impedance 4. A filter 10 converts the instantaneous value to a value proportional to the average bonder power, VI Cos theta. This signal at a terminal 11 is useful for controlling the bonding operation.

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Ultrasonic Welding/Real Power Monitor

The circuit of the drawing measures the power applied to an ultrasonic bonder and the load on the bonder tip. The bonder is represented schematically by a signal source 2, a source impedance 3, and a load impedance 4. The voltage e that appears across load 4 is a component of the power applied to the load. A resistor 5 of low-resistance value is connected in the circuit to produce a voltage el that is proportional to the load current. Operational amplifiers 7 and 8 apply these voltages to a multiplier circuit 9 that produces an output eel, which signifies the instantaneous value of power applied to impedance 4. A filter 10 converts the instantaneous value to a value proportional to the average bonder power, VI Cos theta. This signal at a terminal 11 is useful for controlling the bonding operation.

Circuits 12, 13 and 14 receive the instantaneous voltage signal at the output of operational amplifier 7 and produce on line 15, a signal proportional to the RMS value of the voltage. Circuit 12 forms the square of the instantaneous voltage value. Circuit 13 filters the squared value to remove the double- frequency term and circuit 14 forms the square root of this value, as is required to convert an instantaneous voltage to an RMS voltage. Output 15 is combined in a divide circuit 16 with the average power value at terminal 11 to produce the quotient, I Cos theta. This signal is also useful for controlling the bonding operation.

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