초록 ▼

The package includes a body and a closure. A readily breakable electrical oscillatory network sans power supply is physically connected between the body and the closure. The network is tuned to resonate at a predetermined frequency. The package is monitored by a transmitter-receiver when it is distr

The package includes a body and a closure. A readily breakable electrical oscillatory network sans power supply is physically connected between the body and the closure. The network is tuned to resonate at a predetermined frequency. The package is monitored by a transmitter-receiver when it is distributed to a customer. The transmitter produces pulse signals in a carrier frequency band which overlaps the resonant frequency of the network. During monitoring the package is placed in the field of the transmitter and the oscillatory network is excited to produce a decaying pulse for each transmitter pulse. The receiver is gated during the interval when each transmitter pulse is generated but is receptive of the corresponding decaying pulse from the network. If the package is sealed, the oscillatory network is intact and the receiver receives decaying pulses which produce visual or audible signals. If the package has been opened, the network is broken and no signals are produced.

대표청구항 ▼

A closed container including a body and a closure for closing said body, at least one electrical oscillatory network having no power supply including a capacitor and an inductor, and means connecting said network at one region thereof to the internal surface of said closure and at another region the

A closed container including a body and a closure for closing said body, at least one electrical oscillatory network having no power supply including a capacitor and an inductor, and means connecting said network at one region thereof to the internal surface of said closure and at another region thereof to said body so that when said container is opened by removal of said closure from said body said network is broken.