Automatic Means to Trigger RFID Transmitters

• US 20100194535A1
• Filed: 04/12/2010
• Published: 08/05/2010
• Est. Priority Date: 10/17/2008
• Status: Active Grant

• Current Assignee: Michael Kenneth Pedigo
• Original Assignee: Michael Kenneth Pedigo
• Inventors: Pedigo, Michael Kenneth
• Granted Patent: US 8,174,364 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

An RFID reader requires significant levels of power supply current, upwards or beyond 0.5 amps. Much of this power requirement is expended to activate the reader'"'"'s radio frequency transmitter. For example, the reader'"'"'s transmitter may constantly be active awaiting a RFID tag entering within its electromagnetic field. This is the usual operation for readers utilized in door entry security, inventory control, shipping and receiving management, and contactless point of sale. However, sometimes an adequate power source, such as AC mains, is not available to provide continuous transmitter operation and instead a battery is used to power the reader.

This invention detects that a RFID tag is within reader range without using the reader'"'"'s RF transmitter at full power. As a RFID tag is brought within range of a reader'"'"'s antenna there is significant mutual inductance coupling between the tag antenna and the reader'"'"'s antenna and this invention provides an especially sensitive detector of this mutual inductance. The detection of mutual inductance automatically triggers the reader'"'"'s transmitter to a higher power which is necessary to fully activate the RFID tag.

Claims

1. A radio frequency identification (RFID) system that includes;

an antenna,

an antenna switch,

a phase lock loop,

a RFID decoder,

and a microcontroller or microprocessor.

2. A radio frequency identification (RFID) system of claim 1 wherein said antenna switch connects either said RFID decoder or said phase lock loop to said antenna.

3. A radio frequency identification (RFID) system of claim 1 wherein said phase lock loop includes a voltage controlled oscillator (VCO) that is phase locked to the RFID carrier frequency.

4. A radio frequency identification (RFID) system of claim 1 wherein said microcontroller or microprocessor provides an antenna switch control signal to said antenna switch.

5. A radio frequency identification (RFID) system of claim 1 that has an electrically selectable configuration that places said radio frequency identification (RFID) system into a low power consumption configuration wherein said antenna is connected through said antenna switch to said phase lock loop.