| 摘要 |
A high frequency magnetic field exposure meter for use in an induction heat sealing operation for heat sealing the metal foil elements in closures 1 to the container 2 to be closed by said closure 1. The meter comprises a magnetic field sensing coil 16; a rectifier 17 to convert the a.c. output from said coil to a d.c. output; an integrating circuit 18 to integrate said d.c. output over an exposure period to a h.f. magnetic field 13; a display device 19 to indicate the integrated exposure value generated by the said integrating circuit 18. During operation the meter generates a quantitative reading indicating exposure to the h.f. magnetic flux as an integral of the magnetic flux, which generates the induction heating currents, over the exposure period during the induction heat sealing operation and said reading provides a useful measure of the induction heating generated in an induction heat sealable closure 1. <IMAGE> |
