Method and apparatus for deactivating electromagnetic detection

Details Method and apparatus for deactivating electromagnetic detection Method and apparatus for deactivating electromagnetic detection

1991-01-25

1992-10-06

Ng, Jin F.

Communications: electrical

Condition responsive indicating system

Specific condition

34082514, 34082572, G08B 1314

Patent

active

051535629

ABSTRACT:
A method of deactivating electromagnetic detection labels comprising a resonant circuit, in which an interrogation field is generated, the frequency of which is varied through a frequency range comprising the resonant frequency of the resonant circuit of the detection label, and in which a label is deactivated with an amplified interrogation field. According to the invention, the frequency of the interrogation field is continuously and periodically varied between a first and a second frequency; upon detection of a detection label, the resonant frequency of the label is detected, and at at least one of the subsequent times the periodically varying frequency passes the detected frequency, the field intensity at the location of the detection label is greatly increased for a short period of time. Apparatus for deactivating detection labels comprises a transmitter/receiver comprising a transmitter/receiver circuit for generating an interrogation field with a continuously and periodically varying frequency, and determining at what value of the varying frequency a label is detected; and a circuit for greatly increasing the field intensity for a short period of time at one or more moments when the value of the varying frequency is again reached.

REFERENCES:
patent: 3810147 (1974-05-01), Lichtblau
patent: 4567473 (1986-01-01), Lichtblau
patent: 4728938 (1988-03-01), Kaltner
patent: 4876555 (1989-10-01), Jorgensen
patent: 4906974 (1990-03-01), Rehder
patent: 4920335 (1990-04-01), Andrews
patent: 5012225 (1991-04-01), Gill

Affiliated with

Also associated with

Rating

Method and apparatus for deactivating electromagnetic detection does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method and apparatus for deactivating electromagnetic detection , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for deactivating electromagnetic detection will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1192440