NZ242558A - Electronic identity tag reading system; preset code includes unique identifying sequence - Google Patents

Description

NEW ZEALAND PATENTS ACT, 1951 No.: 242558 Date: 30 April 1992 COMPLETE SPECIFICATION "Improvements in or Relating to a Method of Identifying Articles and/or an Article Identifying Means"" We, DAIRYING RESEARCH CORPORATION LIMITED, a company duly incorporated under the laws of New Zealand of 136 Silverdale Road, Hamilton, New Zealand hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- N.Z. PATENT OFFICE 2 2 AUG 1998 rlccived 24 2 5 5 8 This invention relates to methods and means for identifying articles and, in particular, though not necessarily solely, identifying animals.

Identifying methods and means for articles such as animals are in current use or disclosed in a number of different forms. In particular, a form of identifying method and means is disclosed in New Zealand Patent Application No. 233489. The method and apparatus described in that application requires a contact between a milking claw or the like carrying a contact point to the identity tag on the animal. The specification also refers to the use of a liquid jet for providing the conduction path between the reading means and the identity tag. However, the system described in that specification has some difficulty in operating reliably in regimes where the conduction path between the reading means and the identity tag is poor. In particular, the system as described in that complete specification would not allow an operator or farmer to act as the conductive path between the conduction point on the milking claw and the identity tag. Problems associated with the apparatus described in New Zealand Patent Application No. 233489 when an operator or fanner forms part of the circuit include insufficient voltage maintained across the tag integrated circuits to keep them functioning. The difference between the currents drawn by the tag during one logic state and the other is very small with respect to the total current drawn making identification of the logic states very difficult and the shape of the clock wave form degenerated causing clocking failures.

Therefore, it is an object of the present invention to provide a method of identifying articles and/or an article identifying means which overcomes at least some of these problems or at least provides the public with a useful choice. 1 Z. r'A! ^ OFF'1CE*""| S 2 2 AUG t996 RECEIVED 24 2 5 5 8 In a first aspect, the invention consists in identifying means for identifying an article comprising: a power supply generating an oscillating bipolar signal to a supply point; an identity tag for fitment to an article, said identity tag including signal varying means adapted to vary said signal from said power supply, when in a circuit with said power supply, in a unique manner in accordance with a preset code, said preset code including a non-unique calibration sequence and a unique identifying sequence, such that said varied signal has a calibration portion and an identifying portion; reading means associated with said power supply to sense said varied signal in said circuit and processing means to analyse said sensed signal and determine the identity of the tag and thereby the identity of the article to which the tag is fitted, said processing means including calibration means to calibrate said processing means according to said calibration portion of said signal and identification means to determine the identity of the tag according to said identification portion of said signal.

In a further aspect, the invention consists in A method of identifying an article comprising the steps of: supplying an oscillating bipolar signal to a supply point; providing a conduction path from said supply point to an identity tag fitted to an article, said identifying tag including signal varying means to vary said signal from said power supply when in a circuit with said power supply, in a unique manner in accordance with a preset code, said preset code including a non-unique calibration 24 2 5 5 8 sequence and a unique identifying sequence such that said varied signal has a calibration portion and an identifying portion; sensing at said supply point said varied signal in said circuit; and processing said sensed signal to determine the identity of the tag and thereby the identity of the article to which said tag is fitted, said processing including setting calibration parameters according to said calibration portion of said signal, and determining the identity of the tag according to said identifying portion of said signal in accordance with said calibration parameters.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

The preferred form of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a diagram of an identity tag fitted to a leg of an animal in accordance with the invention; Figure 2 is a diagrammatic view of a reading means and milking claw used in conjunction with one embodiment of the invention; Figure 3 is a block diagram of the reader hardware; Figure 4 is a circuit diagram of an identity tag in accordance with the invention; and ! ■ 7. f'MieiMT OFFICE ! 2 2 AUG 1996 -4- | j RECEIVED 2425 58 Figure 5 is a flow diagram for software used in the micro-processor for the analysis of the signal in accordance with the invention.

Referring to the drawings, identifying means are provided which include an identity tag 1 which may be fitted to an article such as, in this case, the leg of a cow 4. This fitment may include a strap 5 onto the leg 4.

The identity tag 1 includes a contact terminal 2 in the form of, for example, a contact plate.

A ground contact 3 is also provided on the identity tag 1 that is able to allow a path to ground either directly or through the article 4 to which the identity tag is fitted.

The identifying means also includes a reading means 6 which, in this case, is connected to a cow shed rail 7. The reading means 6 provides an isolating signal to a supply point 9 which, in this case, is provided on a milking claw 8. This signal may be supplied to the milking claw 8 and contact point 9 by a connecting cable 10.

Referring now to Figure 3, an oscillating bi-polar signal is produced which, in this case, comprises a signal oscillating between +12 volts and -12 volts. This signal is transmitted to the supply point or reader touch plate 9.

When the reader touch plate 9 is in communication with the contact plate 2 on the identity tag, the identity tag varies the signal produced such that sensing means 12 may sense the varied signal and supply information representative of the varied signal to processing means 13 such as a microcomputer for analysis.

It should be noted that the term microcomputer is used for the processing means. This could, of course, be a microprocessor, however, the incoming signal is in analogue form. To be processed by a microprocessor, it is necessary to convert this , -5- I : 2 2 AUG 1996 2425 5 signal into a digital input to the processor and, therefore, the term microcomputer is used as microcomputers generally have such hardware within them.

The identity tag 1 varies the signal in a manner unique to that identity tag. By sensing and analysing the varied signal, the processing means 13 can determine the identity of the tag and thereby the identity of the article to which it is known to be fitted.

In this particular embodiment, the microcomputer 13 produces digital outputs which are sent to a polarity switch 14 connected to a current supply. The output of this polarity switch is an oscillating bi-polar signal which is sent to the reader touch plate 9. When the reader touch plate 9 communicates with the contact plate 2 on the identity tag, the identity tag is energised.

As shown in Figure 4, the identity tag 1 includes a diode bridge 23 for full wave rectification of the incoming oscillating signal. The DC current output from this diode bridge is used to energise a shift register 24 which, in this case, comprises three integrated circuits. The shift register 24 is made up from three integrated circuits and can contain a 24 bit code which is unique to the identity tag. As the oscillating signal is received by the identity tag, each oscillation causes a single bit of the 24 bit code to be pushed out of the shift register 24. This code is in the form of a high or low and is received by a transistor 25 adjacent the contact plate 2. As each, for example high, point of the code is received by the transistor 25, the transistor allows a direct path to be created from the contact plate 2 to the ground contact 3. This effectively short circuits the rest of the identity tag circuitry and by doing so, will vary the resistance of the identity tag. This variation in resistance will cause increased current to be drawn , 5 N.z. PATENT OFFICE -6- j : — 2 2 AUG 1996 j —; { RECEIVED 242558 from the power supply and this increase in current can be measured by the sensing means 12 which senses the voltage across the resistor 30 in the reader hardware.

The output of the sensing means 12 is filtered by filter 31 to remove noise and applied to the processing means such as microcomputer 13 as an analogue input.

Referring again to the identity tag as shown in Figure 4, it should be noted that the tag includes a diode 34 in series with the transistor 25. This prevents the transistor drawing reader current during negative excitation and, when combined with the tag bridge rectifier 23, maintains voltage across the integrated circuits even while the transistor 25 is intermittently short circuiting the integrated circuits during positive excitation of the tag.

It should be noted that a 24 bit code is used in this embodiment, however, any other convenient length of code could be used. In this case, the 24 bit code includes a 4 bit code which is used as a check from the resistance in the remainder of the circuit. Obviously, conditions for the circuit for different animals or different environmental conditions can cause large variations in the resistance of the circuit as a whole. Therefore, the check sequence in the code is used to define a margin and logic levels on which the software as shown in Figure 5 operates.

Preferably, these check bits form the first 4 bits of the coded sequence.

A further 4 bits of the sequence for this embodiment, preferable the last 4, are used as a check sum to check the bits read in. These are used in much the same way as parity bits in computer hardware.

Figure 5 shows a full diagram for the analysis of the coded signal return to the microcomputer from the identity tag. -7- | N Z. PATENT QFFiCfc , 2 2 m 1996 ; RECEIVED 24 2 5 5 8 The system will generally operate at a current of no greater than 1 milliamp.

This will allow an operator or farmer to act as the bridge between the power supply point 9 on the milking claw 8 and the contact plate 2 on the identity tag 1 and the limit of 1 milliamp should ensure the welfare of both animal and operator.

The use of the bi-polar wave form so that the tag may be continuously powered and the greatly improved detector software which dynamically assesses the signal current level margins for distinguishing the on and off states and tracks drifts in the overall signal level during the measurement allows the system as a whole to operate in conditions where conventional systems could not reliably operate. In particular, they allow an operator to be used as the conductive path between the supply point 9 and the contact plate 2.

This means that the operator or farmer can simply hold the milking claw 8 in one hand and touch the identity tag 1 on an animal for the system to work in the identity of the tag to be read. This is more convenient than the system as disclosed in the prior art in which direct contact occurred.

N.Z. PATENT OFFICE 2 2 AUG 1996 FCCEIVED 242558

Claims (8)

WHAT WE CLAIM IS:

1. Identifying means for identifying an article comprising: a power supply generating an oscillating bipolar signal to a supply point; an identity tag for fitment to an article, said identity tag including signal varying means adapted to vary said signal from said power supply, when in a circuit with said power supply, in a unique manner in accordance with a preset code, said preset code including a non-unique calibration sequence and a unique identifying sequence, such that said varied signal has a calibration portion and an identifying portion; reading means associated with said power supply to sense said varied signal in said circuit and processing means to analyse said sensed signal and determine the identity of the tag and thereby the identity of the article to which the tag is fitted, said processing means including calibration means to calibrate said processing means according to said calibration portion of said signal and identification means to determine the identity of the tag according to said identification portion of said signal.

2. An identifying means as claimed in claim 1 wherein said signal varying means varies its internal resistance with respect to time in accordance with said preset code.

3. An identifying means as claimed in claim 1 or claim 2 wherein said calibration means defines a margin and logic levels for use by said identification means.

4. An identifying means as claimed in any one of the preceding claims wherein said unique identifying sequence includes a verifying sequence, said verifying sequence derived from the remainder of said preset code, and said processing means includes -9- N.Z. PATENT OFFICE 2 2 AUG 1996 RECEIVED Cm "V tm <J %J verifying means which derive a comparative sequence from said identification portion of said signal, and compare said comparative sequence to said verifying sequence to check the accuracy of the reading and notification means which provide a notification to the user dependent on the accuracy of said reading.

5. A method of identifying an article comprising the steps of: supplying an oscillating bipolar signal to a supply point; providing a conduction path from said supply point to an identity tag fitted to an article, said identifying tag including signal varying means to vary said signal from said power supply when in a circuit with said power supply, in a unique manner in accordance with a preset code, said preset code including a non-unique calibration sequence and a unique identifying sequence such that said varied signal has a calibration portion and an identifying portion; sensing at said supply point said varied signal in said circuit; and processing said sensed signal to determine the identity of the tag and thereby the identity of the article to which said tag is fitted, said processing including setting calibration parameters according to said calibration portion of said signal, and determining the identity of the tag according to said identifying portion of said signal in accordance with said calibration parameters.

6. A method as claimed in claim 5 wherein said unique identifying sequence of said preset code includes a verification sequence derived from said preset code, and said processing includes deriving a comparative sequence from said sensed signal and comparing said comparative sequence and said verification sequence to check the accuracy of said sensed signal. -10- N.Z. PATENT OFFICE 2 2 AUG 1995 -1 ^ 1V:' n 24 2 5 5 8

7. Identifying means as claimed in claim 1 and substantially as hereinbefore described with reference to the accompanying drawings,

8. A method of identifying articles as claimed in claim 5 and substantially as hereinbefore described with reference to the accompanying drawings. DATED THIS ?, I DAYOfOL^lo^S A.J. PARK & SON agents f3r Ihe ifetor t-^iuNT OFFICE -11- 2 2 AUG 1996 ALCG'VED