Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1998-12-18
2001-01-09
Hofsass, Jeffery A. (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S572700, C340S010400, C343S719000
Reexamination Certificate
active
06172608
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a system for remote identification of or telemetry from objects using electronically interrogatable coded labels. In particular the invention relates to a system for automated identification of articles in a warehouse or in a cargo shipping system wherein an electronic sub-system called an interrogator including a transmitter and receiver extracts by electromagnetic means useful information from an electronically coded label attached to such articles as they are processed through sorting operations or are stacked, inventoried or collected within a warehouse. Although the present invention is herein described with reference to warehouse operations, it is to be appreciated that it is not thereby limited to such applications. Thus the identification or telemetry system of the present invention may be applied to object identification operations generally.
BACKGROUND OF THE INVENTION
A simplified diagram of the type of system to which the invention relates is shown in FIG.
1
. The system uses the principle of electromagnetic communication in which an interrogator containing a transmitter generates an electromagnetic signal which is transmitted via an interrogator antenna to an electronic label containing a label receiving antenna. The label antenna may receive a proportion of the transmitted energy, and through a rectifier may generate a DC power supply which may be used for operation of a reply generation circuit, connected either to the label receiving antenna or to a separate label reply antenna, with the result that an information bearing electromagnetic reply signal is transmitted from the label back to the receiver of the interrogator.
In the diagram of
FIG. 1
the antennae within the interrogator and the label take the form of inductive loops. When separation between the interrogator and the label is much less than a wavelength at the operating frequency, the principal form of direct coupling between such inductive loops is provided by reactive energy storage fields surrounding those antennae and is expressed in terms of mutual inductance depicted as M
1
in
FIG. 1
, between those loops.
In practical installations of electronic labelling systems it is desirable that labels be robust, easy to install and of low cost, All of these considerations suggest that the labels, and hence the coupling loop within the labels, be made physically small. Because some components within the label may also be fragile, it is sometimes desirable that the label be embedded well within rather than attached to the object being identified.
All these considerations combine to make the interrogation range which may be achieved with such labels and within practical restraints smaller than is desirable. This limitation is particularly relevant where the object to be identified is large, and its placement in relation to the interrogator is uncertain. Although the problem of limited interrogation range of the label can be alleviated somewhat by insuring that it is placed close to the edge of the object to be identified, there frequently occur situations in which objects to be identified are stacked, so that other objects prevent ready access of an interrogator antenna to an edge of the object closest to the label position.
One solution to this problem could be the use of a large antenna placed externally to the label, and directly connected thereto. However, such a solution generally leads to labels becoming of an unacceptable cost and fragility, and being of unsuitable dimensions for attachment to a variety of objects.
SUMMARY OF THE INVENTION
In one aspect of the present invention the problems discussed in the preceding paragraphs may be alleviated by the addition of a parasitic antenna, sometimes known as an auxiliary antenna, which while not being directly connected to the label, does have some coupling thereto, and has coupling also to the interrogator antenna. Such coupling between the interrogator antenna and the parasitic antenna can, either as a result of the parasitic antenna being physically large or through a portion of it lying close to the interrogator antenna, easily exceed direct coupling between the interrogator and the label. Thus the parasitic antenna may through being of a larger size collect more energy from the interrogation field, which may by virtue of electromagnetic compatibility regulations, be constrained to have a low value.
The parasitic antenna may in addition visit more of the external regions of a large item to be identified, so that however that item is stacked, there is the possibility of bringing the antenna of an interrogator system into reasonable proximity to the parasitic antenna. In addition, the parasitic antenna may be shaped or oriented to be responsive to more field directions than is practicable for the label antenna itself. Moreover, the parasitic antenna may be made conformable to a range of objects of shape unpredictable at the time of manufacture of the label itself, or to objects whose shapes change over time.
The parasitic antenna may also simultaneously provide enhanced coupling between an interrogator and a plurality of electronic labels which the interrogator interrogates either simultaneously or within a short space of time.
In all of these circumstances the parasitic antenna preferably should have appropriate coupling to the label antenna or the label circuits, so that a significant portion of the energy received by the parasitic antenna may be transferred to the label, and a significant portion of the reply generated by the label may in turn be transmitted via the parasitic antenna back to the interrogator.
According to the present invention there is provided an identification and telemetry system including an interrogator containing an interrogator antenna for generating at an interrogation frequency an interrogation signal adapted to excite over an electromagnetic coupling path at least one coded label containing a label antenna and a label microcircuit, said coded label being adapted to extract energy from said label antenna and to generate a label reply signal, said label reply signal being adapted to be conveyed to a label reply antenna and via an electromagnetic coupling path to a receiver in said interrogator, wherein said label antenna is placed in proximity to a further antenna being a parasitic antenna coupled electromagnetically with said interrogator antenna and with said label antenna so as to enhance transfer of power between said interrogator and said coded label.
According to one aspect of the present invention the coupling between the further or parasitic antenna and both interrogator and label may be provided by mutual inductance. This is a non-contact form of coupling which may provide significant advantages in installation, in that there is no necessity for electrical contacts to be made or exposed, and thus the disadvantages of such contacts which include corrosion or accidental damage to the label through direct electric contact to damaging potentials may be avoided. In addition installation is simplified as the time to make contacts may be eliminated from the installation procedure.
According to another aspect of the present invention, such coupling either between the label and the parasitic antenna or between the parasitic antenna and the interrogator can be provided by mutual capacitance. The latter may be created by placing elements in proximity.
Coupling between the label antenna and the parasitic antenna may be further enhanced by shaping the parasitic antenna so that currents therein produce enhanced electromagnetic fields in the small region occupied by the label antenna.
According to another aspect of the invention, the parasitic antenna can be made resonant at the operating frequency of the interrogation system. It is particularly advantageous if this resonance could be created by appropriate shaping of the parasitic antenna to create an appropriate combination of inductance, capacitance and flux collecting area, without there being any contacts made within
Hofsass Jeffery A.
Integrated Silicon Design Pty. Ltd.
Larson & Taylor PLC
Tweel , Jr. John
LandOfFree
Enhanced range transponder system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Enhanced range transponder system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Enhanced range transponder system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2555727