| Electronic devices and systems -> Monitor Keywords |
|
|
 
Electronic devices and systemsElectronic devices and systems description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060290475, Electronic devices and systems. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This patent application is a continuation of, and incorporates by reference the entire disclosure of, U.S. patent application Ser. No. 10/525,408, which has been accorded a filing date of Apr. 17, 2006. U.S. patent application Ser. No. 10/525,408 is a national-stage filing of PCT/AU2003/001072, filed Aug. 23, 2003. FIELD OF INVENTION [0002] In arrangements the invention has been developed primarily as a radio frequency identification ("RFID") tag for a parcel, document or postal handling system and will be described hereinafter with reference to these applications. However, the invention is not limited to those particular fields of use and is also suitable to inventory management, stock control systems, and other applications. [0003] The present invention provides novel and inventive electronic devices. BACKGROUND ART [0004] Passive RFID tags are known, and generally include a resonant tuned antenna coil electrically connected to an integrated circuit (IC). Examples of such RFID tags include: U.S. Pat. No. 5,517,194 (Carroll et al); U.S. Pat. No. 4,546,241 (Walton); U.S. Pat. No. 5,550,536 (Flaxel); and U.S. Pat. No. 5,153,583 (Murdoch). [0005] Systems that employ RFID typically include an interrogator that generates a magnetic field at the resonant frequency of the tuned antenna coil. When the coil is located within the magnetic field, the two couple and a voltage is generated in the coil. The voltage in the coil is magnified by the coil's Q factor and provides electrical power to the IC. With this power, the IC is thereby able to generate a coded identification signal that is ultimately transmitted to the interrogator. [0006] Limitations arise because the resonant current that flows in the tuned antenna coil also generates a magnetic field in the region of the coil. That is, if there is an object--such as a second tag with a second coil--disposed near the first coil, the voltage generated by the first coil (and the second coil as well) will be reduced by the partial cancellation--or even complete cancellation--of these respective fields. In turn, this consequential reduction in power will not allow the first tag (and likely the second tag as well) to reliably provide an identification signal to the interrogator. [0007] In this light, many fields that employ such tags--such as baggage handling services, letter carrying services, inventory management systems, etc.--cannot be processed in "dense" configurations. In other words, such articles must be sufficiently spread apart for the tags--and systems incorporating such tags--to operate reliably. Such "density" limitations thus tend to result in speed and efficiency restrictions. [0008] In order to address these problems several inventive arrangements have been developed. As mentioned above and whilst these arrangements have been developed with particular regard to radio frequency identification systems that clearly also have advantageous application in a number of other applications. [0009] The discussion of the prior art within this specification is to assist the addressee understand the invention and is not an admission of the extent of the common general knowledge in the field of the invention. SUMMARY OF INVENTION [0010] According to a first aspect of the invention there is provided a device having a switched impedance that can be switched between a first state and a second state wherein, in the first state, the device acts as a voltage multiplier and, in the second state, the device acts as a rectifier. [0011] Preferably in the first state the device acts as a voltage doubler and in the second state the device acts as a full wave bridge rectifier. Furthermore the switched impedance preferably comprises a switch in series with a capacitor. [0012] In preferred embodiment, the full wave bridge rectifier comprises a Wheatstone bridge diode arrangement having a first and a second input and a first and a second output, with the switched impedance being connected between a first input terminal and a first output terminal of the diode arrangement. As such the switched impedance may be connected between a first input terminal and a first output terminal of the rectifier. [0013] In the ideal the voltage doubler has a voltage gain of two, and transforms the load impedance by a factor of 8. In contrast, the full wave rectifier, in the ideal, has a voltage gain of one, and transforms the load impedance by a factor of 2. Thus, in arrangements, when embodied in the form of a RFID device with an antenna coil, the voltage doubler circuit is arranged to draw a significantly larger current from the antenna coil, and acts as the normal current state rectifier whilst, in contrast, when the full wave rectifier is switched "on" during a low current state significantly less current is drawn. [0014] Other aspects and preferred aspects are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention. [0015] For example according to a second aspect of the invention there is provided a method of selectively controlling current, the method comprising providing a device operable in one of a first state or a second state, coupling an impedance to the device to enable the switching of the device between a first state and a second state wherein, in the first state, the device acts as a voltage multiplier and, in the second state, the device acts as a rectifier. The method may include using a receiving means to receive a signal, and selectively controlling the amount of current in the receiving means by switching between the first state and the second state. Further preferred features of the invention will become apparent. BRIEF DESCRIPTION OF THE DRAWINGS [0016] Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [0017] FIG. 1 is a symbolic circuit diagram of a preferred embodiment of the invention; [0018] FIG. 2 is a symbolic circuit diagram of the embodiment shown in FIG. 1; [0019] FIG. 3 is a symbolic circuit diagram of a voltage doubler circuit associated with the embodiment of the invention shown in FIGS. 1 and 2; Continue reading about Electronic devices and systems... Full patent description for Electronic devices and systems Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Electronic devices and systems patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Electronic devices and systems or other areas of interest. ### Previous Patent Application: Wireless communication device interconnectivity Next Patent Application: Improved coupling of communications signals to a power line Industry Class: Communications: electrical ### FreshPatents.com Support Thank you for viewing the Electronic devices and systems patent info. IP-related news and info Results in 0.31884 seconds Other interesting Feshpatents.com categories: Accenture , Agouron Pharmaceuticals , Amgen , AT&T , Bausch & Lomb , Callaway Golf 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
