US5559507A — Signal transmission and tag reading circuit for a…

Claim 1

Independent Claim 211 words

A signal transmission and tag power variation measurement circuit for an inductive tag reader wherein the tag reader is operative with a tag having an ID means for providing a data signal and a receiving coil coupled to the ID means for inducing a power supply voltage, the tag reader including a differential driver means coupled to a power source for producing first and second complementary drive signals, the gag power variation measurement circuit comprising: a coil having first and second ends; paired capacitors, including a first capacitor for first differentially coupling said first complementary drive signal to said first end of the coil, and a second capacitor for second differentially coupling said second complementary drive signal to said second end of said coil, wherein each of said first and second differential couplings generates an electromagnetic field which is emitted from said coil, and wherein both of said first and second capacitors sense a data signal output from the tag; rectifier means coupled to the first and second sides of the coil means in parallel with said capacitance bank for producing a rectified encoded signal representing the data signal; and signal conversion means, coupled to said rectifier means, for providing an output signal representative of the data signal of the tag.

Claim 2

Dependent Claim 211 words

A signal transmission and tag power variation measurement circuit for an inductive tag reader wherein the tag reader is operative with a tag having an ID means for providing a data signal and a receiving coil coupled to the ID means for inducing a power supply voltage, the tag reader including a differential driver means coupled to a power source for producing first and second complementary drive signals, the gag power variation measurement circuit comprising: a coil having first and second ends; paired capacitors, including a first capacitor for first differentially coupling said first complementary drive signal to said first end of the coil, and a second capacitor for second differentially coupling said second complementary drive signal to said second end of said coil, wherein each of said first and second differential couplings generates an electromagnetic field which is emitted from said coil, and wherein both of said first and second capacitors sense a data signal output from the tag; rectifier means coupled to the first and second sides of the coil means in parallel with said capacitance bank for producing a rectified encoded signal representing the data signal; and signal conversion means, coupled to said rectifier means, for providing an output signal representative of the data signal of the tag.

Claim 3

Dependent Claim 173 words

Apparatus for measuring power variations in an inductively coupled tag reader system, wherein the system includes a tag having ID means for providing a data signal and a receiving coil coupled to the ID means, and tag reader means having differential driver means coupled to a power source for producing first and second complementary drive signals, the apparatus comprising: field coil means for receiving the first and second complementary drive signals through a first and second capacitor, respectively, each capacitor being coupled at a respective end of said field coil means, and for producing an electromagnetic field in the field coil to induce a voltage in the receiving coil proportional to the data signal of the tag; rectifier means coupled to the field coil means for producing a rectified output signal indicative of the data signal of the tag comprising a DC element and an AC element superimposed on the DC element; and filter means coupled to the rectifier means for filtering the rectified output signal and for providing a filtered output signal.

Claim 4

Dependent Claim 173 words

Apparatus for measuring power variations in an inductively coupled tag reader system, wherein the system includes a tag having ID means for providing a data signal and a receiving coil coupled to the ID means, and tag reader means having differential driver means coupled to a power source for producing first and second complementary drive signals, the apparatus comprising: field coil means for receiving the first and second complementary drive signals through a first and second capacitor, respectively, each capacitor being coupled at a respective end of said field coil means, and for producing an electromagnetic field in the field coil to induce a voltage in the receiving coil proportional to the data signal of the tag; rectifier means coupled to the field coil means for producing a rectified output signal indicative of the data signal of the tag comprising a DC element and an AC element superimposed on the DC element; and filter means coupled to the rectifier means for filtering the rectified output signal and for providing a filtered output signal.

Claim 5

Dependent Claim 128 words

An inductively coupled tag reader system for reading data stored in a tag, the reader system comprising: balanced differential coil driver means for producing first and second complementary drive signals; balanced resonant coil means for receiving the first and second complementary drive signals and for routing the first and second drive signals through a coil thereof, the balanced resonant coil means coupling the first complementary drive signal through a first capacitor coupled to a first end of the coil and coupling the second complementary drive signal through a second capacitor coupled to a second end of the coil; detection and filtering means for sensing variations in the power in the coil resulting from inductive coupling with the tag, the variations representative of the data stored in the tag.

Claim 6

Dependent Claim 128 words

An inductively coupled tag reader system for reading data stored in a tag, the reader system comprising: balanced differential coil driver means for producing first and second complementary drive signals; balanced resonant coil means for receiving the first and second complementary drive signals and for routing the first and second drive signals through a coil thereof, the balanced resonant coil means coupling the first complementary drive signal through a first capacitor coupled to a first end of the coil and coupling the second complementary drive signal through a second capacitor coupled to a second end of the coil; detection and filtering means for sensing variations in the power in the coil resulting from inductive coupling with the tag, the variations representative of the data stored in the tag.

Claim 7

Dependent Claim 66 words

The system of claim 3, wherein the balanced resonant coil means further comprises: field coil means for generating an electromagnetic field; means for interconnecting the field coil means and the first and second complementary drive signals; and inductively coupling an electromagnetic field to the tag for inducing voltage and current in the tag to enable the transmission of the data signal to the field coil means.

Claim 8

Dependent Claim 38 words

The apparatus of claim 4, wherein the field coil means further comprises a field coil having first and second inputs and the means for interconnections comprises a pair of equal-valued capacitors for providing a high common-mode noise rejection.

Claim 9

Dependent Claim 88 words

The system of claim 3, wherein the detection and filtering means further comprises rectifier means attached to the field coil means in parallel with the first and second complementary drive signals for converting an induced voltage and current to a rectified power signal comprising a DC element and an AC element superimposed on the DC element, the DC element proportional to a signal from the tag, the AC element proportional to variations in the signal from the tag, the variations representative of the data stored in the tag.

Claim 10

Dependent Claim 21 words

The apparatus of claim 6, wherein the rectifier means further comprises a full-wave bridge rectifier for directly sensing the induced voltage.

Claim 11

Dependent Claim 117 words

An inductively coupled tag reader system for reading data transmitted by a tag, comprising: driver means attached to a signal source for producing first and second complementary drive signals; field coil means for receiving the first and second complementary drive signals and for generating an electromagnetic field inducing a voltage in the tag; and means for inducing a voltage quantitatively related to data transmitted by the tag in the field coil means; rectifier means attached to the field coil means for sensing and converting the induced voltage to an intermediate signal; and filter means attached to the rectifier means for converting the intermediate signal to a filtered output signal representative of the data transmitted by the tag.

Claim 12

Dependent Claim 117 words

An inductively coupled tag reader system for reading data transmitted by a tag, comprising: driver means attached to a signal source for producing first and second complementary drive signals; field coil means for receiving the first and second complementary drive signals and for generating an electromagnetic field inducing a voltage in the tag; and means for inducing a voltage quantitatively related to data transmitted by the tag in the field coil means; rectifier means attached to the field coil means for sensing and converting the induced voltage to an intermediate signal; and filter means attached to the rectifier means for converting the intermediate signal to a filtered output signal representative of the data transmitted by the tag.

Claim 13

Dependent Claim 63 words

The tag reader system of claim 8, wherein the field coil means comprises a coil having a first input, and a second input, wherein the first input is attached through a first capacitor to one of the first and second complementary drive signals and the second input is attached through a second capacitor to another of the first and second complementary drive signals.

Claim 14

Dependent Claim 37 words

The apparatus of claim 8, further comprising first and second capacitors, wherein the field coil means is coupled, at respective ends thereof, to the first and second complementary drive signals through the first and second capacitors, respectively.

Claim 15

Dependent Claim 51 words

The apparatus of claim 8, wherein the field coil means comprises a coil having first and second inputs, the first input being differentially coupled to the first complementary drive signal through a first capacitor, and the second input being differentially coupled to the second complementary drive signal through a second capacitor.

Claim 16

Dependent Claim 32 words

The apparatus of claim 11, wherein each of the first and second inputs is coupled to one of the first and second complementary drive signals by one of the pair of capacitors.

Claim 17

Dependent Claim 27 words

The apparatus of claim 8, wherein the rectifier means comprises a plurality of diodes arranged as a full wave bridge rectifier for directly sensing the induced voltage.

Claim 18

Dependent Claim 37 words

The apparatus of claim 8, wherein the signal source of the driver means comprises an oscillator circuit for producing a recurring signal coupled to a complementary driver circuit for producing the first and second complementary drive signals.

Claim 19

Dependent Claim 14 words

The apparatus of claim 8, wherein the filter means comprises a high impedance filter.

Claim 20

Independent Claim 96 words

A method for reading data transmitted by a tag in an inductively coupled tag reader system comprising the steps of: generating an electromagnetic field using a differential driver means capacitively attached in parallel to a balanced resonant coil detection means; inductively coupling the balanced resonant coil detection means to the tag using the electromagnetic field; inducing a voltage and current in the balanced resonant coil detection means and the tag; and directly sensing variations in the induced voltage and current using a detection and filtering means, the variations representative of the data stored in the tag.

Claim 21

Independent Claim 96 words

A method for reading data transmitted by a tag in an inductively coupled tag reader system comprising the steps of: generating an electromagnetic field using a differential driver means capacitively attached in parallel to a balanced resonant coil detection means; inductively coupling the balanced resonant coil detection means to the tag using the electromagnetic field; inducing a voltage and current in the balanced resonant coil detection means and the tag; and directly sensing variations in the induced voltage and current using a detection and filtering means, the variations representative of the data stored in the tag.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-09-24	2000-03-25	2000-09-24	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-09-24	2004-03-25	2004-09-24	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-09-24	2008-03-25	2008-09-24	$7700.00	Window Closed / Lapsed

Signal transmission and tag reading circuit for an inductive reader

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