« PreviousContinue »
(12) UIllt€d States Patent (10) Patent N0.: US 8,054,160 B2 Corrado et al. (45) Date of Patent: Nov. 8, 2011 (54) RFID TAG POWER CONSERVATION SYSTEM 5,774,876 A 6/1998 Woolley et al. AND METHOD 6,104,295 A 8/2000 Gaisser et al. 6,154,139 A ll/2000 Heller (75) Inventors: Anthony P. Corrado, Nederland, CO i)aIf:)SI::1;>1,‘et al' (US); RBX T- Logan, SHPBIIOL CO (US) 6,614,721 B2 9/2003 Bokhour 6,765,484 B2 7/2004 Eagleson et al. (73) Assignee: Innovation Law Group, Ltd., Sequim, 6,838,992 B2 1/2005 TenarvitZ WA (US) 7,295,108 B2 11/2007 Corrado et al. 2003/0227386 A1 12/2003 Pulkkinen et al. . . . . . 2005/0040241 A1 2/2005 Ra kar ( * ) NOt1Ce3 Sublectlo any d15C1a1mer>_ the term Ofthls 2005/0206503 A1* 9/2005 Coirado et a1, ,,,,,,,,,,,, H 340/10,5 patent 1s extended or adjusted under 35 2006/0065439 A1 3/2006 Oh et 31, U,S,C, 154(b) by 912 days, 2006/0075269 A1 * 4/2006 Liong et al. ................. .. 713/300 (21) Appl NO _ 12/045 553 FOREIGN PATENT DOCUMENTS , WO WO 0133748 A1 10/2001 (22) Filed: Mar. 10, 2008 * cited by examiner (65) Prior Publication Data Primary Examiner i George Bugg US 2008/0218351 Al Sep. 1 1, 2008 Assistant Examiner * Sisay Yacob (74) Attorney, Agent, or Firm * Innovation Law Group, Related U.S. Application Data Ltd_; Jacques M_ Dunn’ ESq_ (60) Provisional application No. 60/894,152, filed on Mar. 9, 2007. (57) ABSTRACT (51) Int_ CL Active multi-modal RFID tags, illuminator/tag/reader sysH04Q 5/22 (200601) tems, circuit architecture and opera-tional algorithms for bat(52) U S Cl 340/10 1_ 340/10 34_ 340/10 4_ tery power conservation that extends tag battery life from a ' ' ' 6"5"_"3"40/10 5 340/10 52, ’340/572'4f typical 6 months to >5 years. The inventive system is particu340/3 1_ 4’0/3 2_ 7'13/300_ 713'/31’0_ 713/32'0f larly useful in asset and person tracking/inventory systems ' ’ ' ’ ’ ’ 713/321’ Where power conservation is critical. The tag is configured . . . With a micro-processor operational instruction set algorithm, (58) Fleld 0f34Cé73ss2lfiga9t;0I; 5 53410;’ modifiable on the fly via RF or IR, to synchro-nize a periodic 340/559 '22’ 53'9 ’26 1 8_ '7I3/3'00’ tag awaken/sense envelope that overlaps the illuminator trig713/310' 32’0 32'4 ’330 37'5’ 400 401’ ger pulse cycle and put the tag into deep, power conservation ’ 73/560 563 60’(L60’1_ 765/28’ sleep forNperiods ofilluminator cycles. When the tag sees an S 1. t. fil f lit ’ h h. t ’ illuminator signal withadifferent ID, or no illuminator signal ee app lea Ion e or Comp e e Seam Is my at all, it transmits that anomaly via RF to a reader. This means (56) References Cited the object or person with which the tag is associated has been
5,640,144 A 6/1997 Russo et al. 5,742,914 A 4/1998 Hagenbuch
moved out of the original illuminator field of view, permitting near real time investigation and tracking.
§__ -. :.,..,,___..~>i Sensors J
U.S. Patent Nov. 8, 2011 Sheet 2 012 US 8,054,160 B2
2B: infra-red Receiver “On” cycie to check for presence of in-fra~red.
1 RFID TAG POWER CONSERVATION SYSTEM AND METHOD
CROSS-REFERENCE TO RELATED APPLICATION
This is the Regular U.S. Application of Provisional Application Ser. No. 60/894,152 filed by the same inventors under the same title on Mar. 9, 2007, the priority of which is claimed under 35 US Code Sections 119, 120 ff.
The invention relates to active bimodal RFID tags, and more particularly to systems, circuit architecture and operational algorithms for conservation of battery power that extends the life of such tags, from a current life of about 6 months, to in excess of 5 years. Such tags are particularly useful in asset tracking and inventory systems in which power conservation is a key commercial criterion.
Radio Frequency Identification (RFID) applications are proliferating as the economies of automated tracking and identification are being realized by the global community. RFID systems of tags and readers provide the ability to detect, read, and/or write data to tags that are affixed to “things” and/or persons to track and further to transfer this data to another computer-related or controlled device for either data storage or action. Cost and utility of the RFID tag are the predominant parameters dictating applicability of this technology.
Hospitals are particularly interested in investing in this technology. Location tracking utilizes a system comprised of tags that respond to a location stimulator, a trigger device (trigger) that cause a tag to respond and readers which record the tag’s output signal that indicates presence and location.
There are two types of RFID tags in the marketplace: passive and active tags. Passive tags convert energy transmitted to them from a reader into a reflected signal that radiates back to the initiating reader device to effect communications. If a metallic or water-laden object is in front of the signal, then the tags will be blocked and not work. Passive readers are large and cumbersome and best suited to fixed installations as field tag read and write capabilities require large readers and direct line of sight. Active tags perform very well but are higher in cost than passive tags and therefore are restricted to specific applications that can carry a higher unit cost.
Battery powered (active RFID) tags provide more functionality, features and reliability than can be realized from passive tags. However, the cost of replacing drained batteries far exceeds the cost of the product and can be the criteria for selection of one device over another. For instance, a battery powered tag can be purchased for $10.00, but the cost of replacing the battery, primarily due to the labor costs of locating, disassembly and battery replacement can be $30$120.00.
As a new class of RFIDs, active (battery powered) bimodal RFID tags suggest promise for a wide range of usages, particularly for indoor applications such as equipment inventory and location. Such tags include both RF and IR communication transmitters, receivers or transceivers, depending on their configuration. However, since they are active tags, they have not had significant impact on the field as they are limited in life by their battery capacity. Current batteries offered Lithium Thionyl Chloride for extended life; Lithium Magne
sium coin-type cells for inexpensive, shorter lived applications; Lithium Iron Phosphate and Lithium Ion types (more expensive); and Alkaline.
For currently available active bimodal RFID tags having both RF and IR transceivers, the battery life is on the order of only ~6-12 months for indoor use. This short battery life is due to the microprocessor instruction set algorithm awakening the tag from a partial power-down state to fully powered every 5 seconds for full processing of any signal detected. Typically, this process includes a scan of a few milliseconds (on the order of 1.5-2.5 msec) to detect an IR or RF signal. e.g., from an illuminator (also called a trigger device), and then an additional time period to fully process the signal for any identification information and signal message content to be acted-on. This frequent repeated cycling to full power to process all incoming signal information rapidly drains the battery, such that the battery must be replaced within ~6-12 months to insure continued operation. In typical enterprises, such as hospitals, ofiices, manufacturing facilities, retail or warehouse operation, research facilities and the like, thousands of such tags are required to implement the equipment inventory and location systems. In addition to the cost of replacement batteries, the necessary staff, record keeping and logistic requirements to keep track of battery check and change-out has created a serious financial barrier to the adoption of such tags for such inventory/location systems.
Although there are improvements in battery technology, there is currently nothing on the horizon that promises more than an incremental 10-20% increase in battery life, not enough to change the financial adoption equation for systems employing active bimodal RFID tags.
In addition, in current systems, the illuminator is always on. However, that not only burns out the power supply of the illuminator, but also causes totally unacceptable “black-out” interference with all other equipment that uses IR or RF to communicate, such as televisions, CD players, computer mice and keyboards, radios, networks, and other IR controllers for equipment, including medical and industrial equipment.
Accordingly, there is a need in the art for a paradigm shift in tag system architecture and functional wake-up and scan algorithms by which such tags operate so that currently available batteries can be used in a manner that they have operational life spans of 5-10 times the currently expected battery life.
THE INVENTION Summary, Including Objects and Advantages
The invention is directed to active, battery powered, multimodal RFID tags having RF, IR, US (ultra-sound) and Laser receivers, transmitters or transceivers that are configured primarily for indoor operation, including novel circuit architecture and operational wake-up and scan algorithms for detection of periodic signal beacons from illuminators that result in significant and unexpected improvements in battery life. More particularly, the invention is directed to a paradigm shift in the operational algorithm, enabled in firmware and unique circuitry, that functions to conserve battery power of active, battery powered, bimodal RFID tags so that they have a useful, functional life on the order of 5 to 10 times longer than a tag powered by the same battery but not having the inventive system. The inventive tags are particularly useful when afiixed to hard assets or personnel
The inventive tags may be configured in several embodiments, e.g., considering a bimodal RF/IR RFID tag, by way of