U.S. patent application number 12/972978 was filed with the patent office on 2011-04-14 for tracking systems, methods of locating and identifying rfids, and methods of tracking items.
This patent application is currently assigned to ROUND ROCK RESEARCH, LLC. Invention is credited to John R. Tuttle.
Application Number | 20110084808 12/972978 |
Document ID | / |
Family ID | 39321445 |
Filed Date | 2011-04-14 |
United States Patent
Application |
20110084808 |
Kind Code |
A1 |
Tuttle; John R. |
April 14, 2011 |
TRACKING SYSTEMS, METHODS OF LOCATING AND IDENTIFYING RFIDS, AND
METHODS OF TRACKING ITEMS
Abstract
Some embodiments include observable properties triggered upon
interrogation of RFIDs. The RFIDs can be passive RFIDs, and the
observable properties can be visible changes that require little
power to generate, and little or no power to maintain. The visible
information can include information about items tracked with the
RFIDs, such as shipping information. Some embodiments include
passive RFIDs utilizing a single antenna to power an
integrated-circuit chip and a visual identifier. Some embodiments
include methods of locating interrogated RFIDs. Some embodiments
include methods of tracking items.
Inventors: |
Tuttle; John R.; (Boulder,
CO) |
Assignee: |
ROUND ROCK RESEARCH, LLC
Mount Kisco
NY
|
Family ID: |
39321445 |
Appl. No.: |
12/972978 |
Filed: |
December 20, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11595683 |
Nov 10, 2006 |
7855643 |
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12972978 |
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Current U.S.
Class: |
340/10.1 |
Current CPC
Class: |
G06K 19/07703 20130101;
G06K 17/00 20130101 |
Class at
Publication: |
340/10.1 |
International
Class: |
H04Q 5/22 20060101
H04Q005/22 |
Claims
1. A tracking system, comprising: an interrogator; and a plurality
of passive RFIDs, at least one of the passive RFIDs being
configured to change an observable visible property responsive to
interrogation by the interrogator, the observable visible property
being a transient change that ceases without power input.
2. The tracking system of claim 1 wherein the observable visible
property transient change has a duration of less than 0.5
seconds.
3. The tracking system of claim 1 wherein the observable visible
property transient change has a duration of less than 10
milliseconds.
4. A tracking system, comprising: an interrogator; and a plurality
of RFIDs configured to change an observable property in the same
way upon being interrogated by the interrogator.
5. The tracking system of claim 4 wherein the observable property
is a visible property.
6. The tracking system of claim 4 wherein the RFIDs are passive
RFIDs, the observable property is a visible property, and the
changed visible property is stable without power input from the
interrogator.
7. The tracking system of claim 4 wherein the observable property
is a transient visible property that ceases without power input
from the interrogator.
8. The tracking system of claim 4 wherein the observable property
is a transient visible property that has a duration of less than
0.5 seconds.
9. The tracking system of claim 4 wherein the observable property
is a transient visible property that has a duration of less than 10
milliseconds.
10. A tracking system, comprising: an interrogator; and at least
one RFID which is configured to display a bar code responsive to
interrogation by the interrogator.
11. The tracking system of claim 10 wherein the at least one RFID
comprises a plurality of RFIDs configured to display bar codes
responsive to interrogation by the interrogator.
12. The tracking system of claim 11 wherein at least two of the
RFIDs of the plurality are configured to display the same bar code
as one another.
13. The tracking system of claim 11 wherein at least two of the
RFIDs of the plurality are configured to display different bar
codes from one another.
14. The tracking system of claim 11 wherein the RFIDs are passive
RFIDs.
15. The tracking system of claim 11 wherein the RFIDs are active
RFIDs.
16. A tracking system, comprising: an interrogator; and at least
one RFID which is configured to display shipping information
responsive to interrogation by the interrogator.
17. The tracking system of claim 16 wherein the at least one RFID
is a passive RFID.
18. The tracking system of claim 16 wherein the at least one RFID
is an active RFID.
19. A method of locating interrogated RFIDs, comprising: providing
an interrogator and a plurality of passive RFIDs, at least one of
the passive RFIDs being configured to change an observable visible
property responsive to interrogation by the interrogator; the
observable visible property change being a transient change that
has a duration of less than 0.5 seconds; and interrogating said at
least one of the passive RFIDs with the interrogator to trigger the
observable visible property.
20. The method of claim 19 wherein the providing the passive RFIDs
comprises providing passive RFIDs which include visible
identification regions comprising at least one of electronic ink,
electronic paper, ferroelectric material, and polymer
electrochromic material; and wherein the observable visible
property change includes an observable change in the at least one
of electronic ink, electronic paper, ferroelectric material, and
polymer electrochromic material.
21. The method of claim 19 wherein the interrogating triggers the
observable visible property transient change to have a duration of
less than 10 milliseconds.
22. A method of identifying interrogated RFIDs, comprising:
providing an interrogator and a plurality of RFIDs, all of said
RFIDs being configured to change an observable property in the same
way upon being interrogated by the interrogator; and interrogating
at least some of the RFIDs to trigger the observable property
change within all of the interrogated RFIDs.
23. The method of claim 22 wherein only some of the RFIDs are
interrogated, and further comprising observing the triggered
observable property change to ascertain an antenna power pattern of
the interrogator.
24. The method of claim 22 wherein the interrogating to trigger the
observable property change comprises triggering a visible property
change.
25. The method of claim 24 wherein the providing the RFIDs
comprises providing RFIDs which include visible identification
regions comprising at least one of electronic ink, electronic
paper, ferroelectric material, and polymer electrochromic material;
and wherein the triggering the visible property change includes
triggering an observable change in the at least one of electronic
ink, electronic paper, ferroelectric material, and polymer
electrochromic material.
26. The method of claim 22 wherein the providing the RFIDs
comprises providing passive RFIDs; the interrogating to trigger the
observable property change comprises triggering a visible property
change; and the triggered visible property change remains without
power input after the triggering.
27. The method of claim 22 wherein the interrogating to trigger the
observable property change comprises triggering a transient visible
property change that has a duration of less than 0.5 seconds.
28. The method of claim 22 wherein the interrogating to trigger the
observable property change comprises triggering a transient visible
property change that has a duration of less than 10
milliseconds.
29. A method of tracking items, comprising: providing an
interrogator; providing RFIDs associated with the items; and
interrogating the RFIDs to cause the RFIDS to display bar codes
which provide information regarding the items associated with the
RFIDs.
30. The method of claim 29 wherein the providing the RFIDs
comprises providing RFIDs which include visible identification
regions comprising at least one of electronic ink, electronic
paper, ferroelectric material, and polymer electrochromic material;
and wherein the causing the RFIDs to display bar codes includes
causing a change in the at least one of electronic ink, electronic
paper, ferroelectric material, and polymer electrochromic
material.
31. The method of claim 29 wherein the interrogating to cause the
RFIDs to display the bar codes comprises causing at least two of
the RFIDs to display the same bar code as one another.
32. The method of claim 29 wherein the interrogating to cause the
RFIDs to display the bar codes comprises causing at least two of
the RFIDs to display different bar codes from one another.
33. The method of claim 29 wherein the RFIDs include passive
RFIDs.
34. The method of claim 29 wherein the RFIDs include active RFIDs.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 11/595,683, filed on Nov. 10, 2006, the disclosure of which is
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention, in various embodiments, relates to
tracking systems, passive radio frequency identification devices
(RFIDs), methods of locating and identifying RFIDs, and methods of
tracking items
BACKGROUND
[0003] RFIDs have numerous uses, including, for example, inventory
tracking.
[0004] RFIDs are utilized in systems with interrogators. The
interrogators communicate with the RFIDs through radio-frequency
(RF) signals. The RFIDs can be either active devices or passive
devices. Active devices have their own power sources, and passive
devices rely solely on power from RF signals sent by the
interrogators.
[0005] Active devices have an advantage in that they can be
utilized further from an interrogator than passive devices, but
have the disadvantage that the power source within the active
devices has a limited lifespan. Also, active devices can be more
expensive than passive devices. Accordingly, passive devices and
active devices each have advantages and disadvantages that can
render one type of device more suitable for a particular
application than the other.
[0006] Present RFID systems have sufficient communications range
between tag and reader such that it is possible that many tags can
be present at one time within a reader antenna working volume.
Thus, when the interrogator reads a tag, the user may not be able
to determine which tag has been read. It could be one of many
because there is no visible indicator of which tag ID corresponds
with which physical tag. There exist applications, such as
inventory management, where an ID number relates to one specific
part. Any uncertainty or ambiguity in such systems may destroy the
integrity of the inventory tracking system. Because passive tags
have no power absent a reader, it has been problematic to provide a
visual indicator means that persists in the absence of incident
reader power on a passive tag.
BRIEF SUMMARY OF THE DRAWINGS
[0007] FIG. 1 is a diagrammatic view of an RFID embodiment.
[0008] FIG. 2 is a block diagram of circuitry of a passive RFID
embodiment.
[0009] FIG. 3 is a block diagram of circuitry of another passive
RFID embodiment.
[0010] FIG. 4 is a block diagram of circuitry of an active RFID
embodiment.
[0011] FIG. 5 is a diagram of a wireless communication system
embodiment.
[0012] FIG. 6 is a diagram of another wireless communication system
embodiment.
[0013] FIG. 7 is a diagram of several tagged items at a preliminary
processing stage of a tracking system embodiment.
[0014] FIG. 8 is a view of the tagged items of FIG. 7 shown at a
tracking stage subsequent to that of FIG. 7.
[0015] FIG. 9 illustrates a visual identification device embodiment
in two different configurations.
[0016] FIG. 10 illustrates another visual identification device
embodiment in two different configurations.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] Various systems and methods are disclosed for incorporating
observable identifiers into RFIDs. The observable identifiers can
be utilized for determining which RFIDs within a group of RFIDs are
interrogated by a particular interrogator. In some embodiments, the
observable indicators can be visible indicators which provide
information about items tracked with RFIDs. Such information can be
displayed as a bar code. Alternatively, or additionally, the
information can be displayed alphanumerically. An example
application utilizing an alphanumeric display is the visual display
of shipping information (for instance, origin, destination or time
of travel information). Alternatively, or additionally, a single
ON/OFF visual indicator area on an RFID tag may serve as an
indicator that an interrogator is presently communicating with that
tag by its ID number. Alternatively, or additionally, multiple
ON/OFF visual indicator areas on an RFID tag may serve as an
indicator that an interrogator is presently communicating with that
tag by its ID number.
[0018] An example of a radio frequency identification device (RFID)
having a visual indicator associated therewith is shown in FIG. 1
as device 10. The device 10 comprises a surface 11. A visual
identification (VID) region 12 is shown formed along a portion of
such surface. Although the shown VID region comprises only a
portion of surface 11, it is to be understood that the visual
identification region may comprise the entirety of surface 11.
[0019] The VID region 12 comprises one or more compositions that
can be modified in some selected characteristic so that a change in
the VID region is perceptible to a person looking at RFID 10. Such
change may be a change in color, and/or a change in an observed
pattern. Suitable compositions for utilization in VID region 12 are
compositions which create visible changes upon being subjected to
electrical power. It can be preferred that the visible changes be
induced with very little power input. For instance, if RFID 10 is a
passive device, there will be little power available to cause a
change. Alternatively, if device 10 is an active device, there will
be more power, but it may still be preferred that as little power
as possible be utilized to change observable properties within
region 12 so that charge can be conserved within the power
reservoir of the active device.
[0020] In some applications, very low power electronic displays
(which can be referred to zero-power electronic displays if the
displays convey information in the absence of power) are utilized
within the VID regions. Very low power displays can be particularly
useful for passive RFIDs, since passive RFIDs have little power
available with which to perform enunciation (with enunciation being
indication by the RFID that it has received a signal from an
interrogator). Passive RFIDs get all of their power from an
interrogator's electromagnetic field, and thus are generally not
powered (except for a little charge remaining on a power supply
capacitor) when an interrogator field is absent. Thus, if a VID
region is going to maintain a perceptible changed state, such as a
visible pattern, in the absence of an interrogator's
electromagnetic field, such should occur with zero power. Examples
of zero-power display technologies are electronic ink, electronic
paper, ferroelectrics, and polymer electrochromics. For instance,
Nemoptic of France manufactures various zero power display
materials.
[0021] FIGS. 2 and 3 show embodiment circuit configurations
suitable for passive RFIDs having VID regions.
[0022] Referring first to FIG. 2, such shows an embodiment of RFID
10 comprising an antenna 14, an integrated circuit chip 16, and
circuitry 18 associated with a VID region.
[0023] The circuitry 18 can comprise a substance which changes in
some characteristic visible to a person observing the VID region
when power is supplied to the substance. The visible change may
include, for example, one or any of a color change, contrast change
and pattern change. The circuitry 18 may be characterized as visual
identifier circuitry. Such visual identifier circuitry may be
configured to respond to power input by altering a visual
identifier observable by a person looking at the VID region 12
(FIG. 1) of RFID 10.
[0024] The integrated circuitry 16 includes RFID circuitry, and
also includes circuitry for controlling flow of power to the visual
identifier circuitry 18. In operation, interrogation of RFID 10
creates power in antenna 14. Such power is directed to circuitry 16
along the path diagrammatically illustrated by arrow 17. A portion
of the power reaching circuitry 16 is in turn directed from
circuitry 16 to visual identifier circuitry 18 along the path
diagrammatically illustrated by arrow 19. FIG. 2 also shows power
flow from RFID circuitry 16 to antenna 14 along a path 15. Such
power flow can be optional. When present, the flow along path 15
enables the RFID to send information out to a receiving device, in
addition to receiving a signal from an interrogator. The receiving
device can be the same as the interrogator that sent communication
to the RFID, or can be different.
[0025] Notably, the RFID of FIG. 2 comprises only one antenna. Such
antenna is configured to power both the RFID circuitry and the
visual identifier circuitry.
[0026] Referring to FIG. 3, another embodiment of a configuration
of circuitry within a passive RFID is illustrated. In the
configuration of FIG. 3, antenna 14 is directly coupled to both
integrated circuitry 16 and visual identifier circuitry 18. Thus,
power flow to visual identifier circuitry 18 proceeds along a new
path 21 that is direct from antenna 14, rather than proceeding
along a path from RFID circuitry 16 (such as the path 19 of FIG.
2).
[0027] The embodiments of FIGS. 2 and 3 may each provide advantages
associated therewith for particular applications. The embodiment of
FIG. 2 may be preferred if it is desired to control power input to
visual identification circuitry 18. The embodiment of FIG. 2 may
also be preferred if it is desired to controllably display patterns
or symbols that are to update or change. In contrast, the
embodiment of FIG. 3 may be preferred if it is desired to merely
have the RFID visually display that it is being interrogated. As
discussed in more detail below, the visual display may show a
pattern or other indication that only lasts about as long as power
is supplied to the RFID, or may change to a stable display that
remains in its altered state for at least some extended period in
the absence of power to the RFID.
[0028] FIGS. 2 and 3 depict embodiments of passive RFIDs, but
visual identification techniques may also be utilized with active
RFIDs. FIG. 4 shows an embodiment of an RFID 10 which is an active
RFID.
[0029] The RFID of FIG. 4 comprises the antenna 14, integrated
circuitry 16, and visual identification circuitry 18 discussed
above; and further comprises a power source 20. The power source 20
can comprise, for example, a battery.
[0030] A signal 21 is shown proceeding from antenna 14 to
integrated circuitry 16. Power from the battery is shown by arrow
23 as being utilized to power integrated circuitry 16. Power is
then directed from integrated circuitry 16 to visual identification
circuitry 18, as shown by arrow 25. Further, power can be directed
from integrated circuitry 16 to antenna 14, as designated by arrow
27.
[0031] The active RFID of FIG. 4 can be utilized alternatively to
the passive RFIDs of FIGS. 2 and 3, or in addition to the passive
RFIDs.
[0032] In the discussion of FIGS. 1-4, the identification region 12
of FIG. 1 is described as a visual identification region. It is to
be understood, however, that other user-identifiable
characteristics may be used in some embodiments. The other
user-identifiable characteristics may be any characteristics that
can be sensed by a person proximate the RFID (such as sound or
touch). However, characteristics other than visual characteristics
can utilize more power than the visual characteristics, and can be
more difficult to quickly and accurately locate. Thus, it may be
desirable to use visual characteristics.
[0033] The RFIDs of FIGS. 1-4 can be utilized in inventory or other
object tracking systems. FIG. 5 illustrates a tracking system 30
which includes an interrogator 32 and a plurality of RFIDs 34, 36,
38 and 40. The RFIDs 34, 36, 38 and 40 contain VID regions 44, 46,
48 and 50, respectively.
[0034] The interrogator 32 outputs a radio frequency signal 52
(diagrammatically illustrated by a plurality of waves) toward RFIDs
34, 36, 38 and 40.
[0035] The RFIDs comprise a first subset corresponding to RFIDs 36
and 38. The first subset is configured to change a user-observable
visible property within VID regions 46 and 48 upon interacting with
RF signals from interrogator 32. The RFIDs also include a second
subset corresponding to RFIDs 34 and 40. The second subset does not
change a user-observable visible property upon being interrogated
by the signal from interrogator 32. In some embodiments, the second
subset does not communicate with the radio frequency of the
interrogator. The RFIDs of the first subset (RFIDs 36 and 38) are
shown to have a "+" (i.e., a plus sign) formed in the VID regions
46 and 48, while the RFIDs of the second subset (RFIDs 34 and 40)
do not have any symbols formed in the VID regions thereof.
[0036] The system of FIG. 5 can be used for locating particular
RFIDs within a group of RFIDs. For instance, the system can be used
for locating the RFIDs 36 and 38 within the group comprising RFIDs
34, 36, 38 and 40. Alternatively, the system can be utilized for
locating the RFIDs 34 and 40 of such group by identifying the RFIDs
which did not change upon being interrogated with the signal from
interrogator 32. In any event, the system 30 can be utilized for
identifying particular RFIDs by configuring a subset of the RFIDs
to change a user-observable property upon interrogation, and
configuring another subset which does not change the
user-observable property upon such interrogation. The first and
second subsets of the RFIDs can then be simultaneously exposed to
interrogation, and the RFIDs that changed the user-observable
property can be distinguished from those that didn't to locate one
of the subsets of RFIDs relative to the other. The RFIDs are
considered to be simultaneously exposed to interrogation by an
interrogator if both are in the RF field of the interrogator at the
same time.
[0037] In some embodiments of the FIG. 5 application, momentary
visual identification of all RFID tags receiving sufficient power
from an electromagnetic field gives a user an observable signal of
which RFID tags are within range of an interrogator. Such signal
can be a visual representation of the range of the interrogator, or
a visual representation of the antenna power pattern when multiple
tags are used. If the signal is used as a visual representation of
an antenna power pattern, there can be a global command from the
interrogator to the RFIDs that says "Whoever you are, if you hear
me, turn on your indicator." This may be useful for verifying
functionality of an antenna installation, and/or finding minimum
acceptable reader power. Both of which may be useful for setting up
new installations, and for quality and/or diagnostic checks of
existing installations.
[0038] The change in the user-observable visibly property utilized
in the FIG. 5 application may be designed to use very little
energy, particularly if the RFIDs are passive RFIDs. Accordingly,
the visual identification region can include one or more of
electronic ink, electronic paper, ferroelectric material and
polymer electrochromic material. The user-observable visible
property can then correspond to a user-observable change in color
or pattern corresponding to a change in one or more of the
electronic ink, electronic paper, ferroelectric material and
polymer electrochromic material.
[0039] The RFIDs may be designed so that power is only required to
be provided to the VID region for a very brief period of time. This
enables a relatively small amount of power to be utilized to
display the visible property change. If the user-observable visible
property change requires power to maintain the property, the
property change may only be displayed for a very brief time to
reduce the amount of power consumed in showing the property change.
For instance, if the "+" symbols shown in VID regions 46 and 48 of
FIG. 5 require power to maintain the symbols, the symbols may only
be displayed transiently. Such transient display can be for long
enough for an observer to glimpse the symbols and identify which
RFID devices reacted to interrogation by interrogator 32, and yet
for a duration that is really no longer than needed for such
glimpse of the reacting RFIDs. For instance, in some embodiments
the visible property can be displayed for less than 0.5 seconds,
and in other embodiments for even less than 10 milliseconds.
[0040] Some electrically stimulated visible materials (such as some
electronic inks and polymer electrochromic materials) are known to
exist in two stable states that can be interchanged with input of
electrical power. Such materials can be utilized in the VID regions
of the RFIDs shown in FIG. 5. Interrogation of such RFIDs can then
trigger a change in the materials from one state to another to
trigger a visible property change corresponding to a new state of
the materials. The new state will remain after power input to the
VID region is ceased, and thus the new visible property will be
stable after the power input is ceased. An example visible property
change is a change from a blank VID region to a VID region
displaying a "+" symbol. Thus, materials that exist in two stable
states can be utilized to display symbols that remain within VID
regions after power input to the VID regions is stopped, rather
than displaying symbols that exist only transiently during the
input of power to the VID regions. Materials that exist in two
stable states can be considered to provide a toggle mode for a
display in a VID region. The display can toggle between the two
states at each communication with an interrogator, and can remain
in either state between communications with the interrogator.
[0041] In the application of FIG. 5, all of the visual
identification regions that reacted to interrogation show the same
visual property (the "+" symbol). Such can be effective if the
purpose of the visual change is to identify which RFIDs reacted to
interrogation. In other applications, some of the RFIDs can display
a different visual property than others. In such applications, the
particular visual property displayed by an RFID can be informative
of an item tagged with the RFID, as discussed below with reference
to FIGS. 7-10.
[0042] The application of FIG. 5 utilized a single interrogator.
Other applications can utilize a plurality of interrogators. For
instance, FIG. 6 shows a tracking system 60 comprising a second
interrogator 62 in addition to the components of the tracking
system 30 of FIG. 5. The system 60 specifically comprises the first
interrogator 32 discussed above with reference to FIG. 5, and
comprises the RFIDs 34, 36, 38 and 40. The RFIDs 36 and 38
correspond to the above-discussed first subset, and display the
user-observable visible property of a "+" symbol upon interrogation
from the first interrogator 32. The RFIDs 34 and 40 correspond to
the above-discussed second subset, and in the embodiment of FIG. 6
respond to interrogation by the second interrogator 62 to display a
"0" symbol. The first subset of RFIDs does not respond to the
interrogation by the second interrogator, and the second subset of
RFIDs does not respond to interrogation by the first interrogator.
The first interrogator can thus be considered to interrogate the
first subset of RFIDs selectively relative to the second set, and
the second interrogator can be thus be considered to interrogate
the second subset of RFIDs selectively relative to the first
set.
[0043] The interrogator 62 is shown to trigger a different visual
property in the second subset of RFIDs than is triggered in the
first subset by the first interrogator. In other applications, the
symbols generated by the first and second interrogators can be the
same as one another.
[0044] A user observing RFIDs 34, 36, 38 and 40 can utilize the
interrogator-generated visible property changes to distinguish
RFIDs that responded to the first interrogator from those that
responded to the second interrogator, and vice-versa. In the
embodiment of FIG. 6, a RFID tag's visual identification changes
state upon being interrogated only by certain interrogators, which
are written to the RFID memory. This embodiment can be used to
identify which of several interrogators are communicating with
particular tags.
[0045] RFIDs having VID regions can be utilized to display
particular information pertaining to tagged items. An example of
such application is discussed with reference to FIGS. 7-10.
[0046] Referring to FIG. 7, a plurality of items 70, 72, 74 and 76
is shown. The items have RFIDs 80, 82, 84 and 86 associated
therewith (in other words, are tagged with RFIDs 80, 82, 84 and
86). The RFIDs can be affixed to the items with glue or tape.
Alternatively, the RFIDs can be fixed to boxes which retain the
items. Regardless, the RFIDs associated with the items move with
the items through a particular process, such as, for example, a
parcel or object sorting process, or mail delivery process.
[0047] Referring to FIG. 8, the items 70, 72, 74, and 76 are
provided within range of an interrogator 90. The interrogator emits
an RF signal 92 which passes across RFIDs 80, 82, 84 and 86. The
RFIDs can emit return signals to the interrogator to pass
information to the interrogator. The RFIDs also have identification
regions which generate patterns in response to the RFIDs being
interrogated by interrogator 90. Such is diagrammatically
illustrated by lines extending across RFIDs 80, 82, 84 and 86. The
lines are shown extending horizontally, but it is to be understood
that the lines may extend vertically, or in any other desired
pattern.
[0048] The symbols formed on the RFIDs may be selected to be
descriptive of one or more properties of the items associated with
the RFIDs, and may be in a form either directly readable by a
person observing the visual identification regions, or readable
with appropriate equipment. For instance, FIG. 9 shows an example
RFID 80 before and after interrogation. Specifically, RFID 80 is
shown on the left side of FIG. 9 before interrogation, and on the
right side of FIG. 9 after interrogation. The interrogation has
generated a bar code 83 across RFID 80. Such bar code can be read
with an appropriate reader to ascertain information about an item
tagged with the RFID. The information may be selected to correspond
to anything of possible interest to a person tracking the item
associated with the RFID, including, for example, delivery
information. In some applications, several of the RFIDs can display
identical bar codes, particularly if the items associated with the
RFIDs are being treated identically to one another at the
processing stage in which the bar codes are displayed. In other
applications, several of the RFIDs can display different bar codes
from one another. Bar codes can be displayed in VID regions with
any suitable material, and in some applications can be displayed
with electronic paper.
[0049] FIG. 10 shows another embodiment of RFID 80 before and after
interrogation, with the RFID being shown in the left side before
interrogation and in the right side after interrogation. The RFID
has printing on its surface which labels "Origin," "Destination,"
and "Last Activity." Interrogation by the interrogator provides
information in locations (i.e., fields) proximate such printing to
convey shipping information to a person observing the RFID.
Specifically, the interrogated RFID indicates the point of origin,
the point of destination, and the last activity that has occurred
relative to the RFID. The RFID may be configured to display other
shipping information alternatively, or additionally, to that
shown.
[0050] The embodiments disclosed herein can be utilized in numerous
applications. Conventional RFIDs typically offer no external
physical indication that they have been, or are being,
interrogated. A range of an interrogator is frequently not
precisely known, so users can have difficulty determining which of
many possible RFIDs have been read. However, placement of indicator
displays on RFIDs in accordance with the embodiments disclosed
herein can permit users to visually identify which RFIDs have been,
or are being, interrogated. The visual identification can be in a
momentary or toggle mode. If the visual identification is in a
momentary mode, the visual identification can change state during
interrogation (for instance, about 10 milliseconds), or for a very
short time after the interrogation (for instance about 0.5
seconds). In some applications, there can be regulatory
restrictions to the length of time that the visual identification
is activated, such as, for example, a time of 0.5 seconds or
less.
[0051] Interrogators can be considered to have "formal" sessions of
communication with RFIDs during which data is exchanged between the
interrogators and the RFIDS. The visual change in a VID region may
be triggered to occur during formal sessions in some applications,
and in other applications the visual change may be timed to occur
before or after the formal sessions. If the visual change occurs
before or after a formal session, the change may be induced by
power provided from the interrogator. The RFID can operate in a
mode to only receive the power and change the visible display,
rather than to also engage in the data communication with the
interrogator that would occur in a formal session.
[0052] In compliance with the statute, the subject matter disclosed
herein has been described in language more or less specific as to
structural and methodical features. It is to be understood,
however, that the claims are not limited to the specific features
shown and described, since the means herein disclosed comprise
example embodiments. The claims are thus to be afforded full scope
as literally worded, and to be appropriately interpreted in
accordance with the doctrine of equivalents.
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