U.S. patent application number 11/934621 was filed with the patent office on 2008-03-13 for method and system for aiming an rfid reader.
Invention is credited to Lihu M. Chiu.
Application Number | 20080061147 11/934621 |
Document ID | / |
Family ID | 37009295 |
Filed Date | 2008-03-13 |
United States Patent
Application |
20080061147 |
Kind Code |
A1 |
Chiu; Lihu M. |
March 13, 2008 |
METHOD AND SYSTEM FOR AIMING AN RFID READER
Abstract
A method and system for enhancing the accuracy of RFID tag
reading is disclosed. An imaging device is used to facilitate
aiming of the RFID tag in a manner that mitigates the likelihood of
inadvertently reading a nearby RFID tag instead of the desired tag.
In this manner, the utility of the RFID reader is substantially
enhanced.
Inventors: |
Chiu; Lihu M.; (Arcadia,
CA) |
Correspondence
Address: |
MACPHERSON KWOK CHEN & HEID LLP
2033 GATEWAY PLACE
SUITE 400
SAN JOSE
CA
95110
US
|
Family ID: |
37009295 |
Appl. No.: |
11/934621 |
Filed: |
November 2, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11073081 |
Mar 4, 2005 |
|
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11934621 |
Nov 2, 2007 |
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Current U.S.
Class: |
235/472.02 ;
340/10.3 |
Current CPC
Class: |
G06K 7/0008 20130101;
G06K 17/0025 20130101; G06K 7/10386 20130101 |
Class at
Publication: |
235/472.02 ;
340/010.3 |
International
Class: |
G06K 7/10 20060101
G06K007/10 |
Claims
1-26. (canceled)
27. A method for making an RFID reader assembly, the method
comprising: providing an RFID reader; providing an imaging device;
attaching the imaging device to the RFID reader, wherein the
imaging device is configured to scan an image of an RFID tag;
coupling a vision controller to the imaging device, wherein the
vision controller is configured to send a signal, based on a signal
received from the imaging device, to the RFID reader when the
selected RFID tag is to be read; and providing a drive controller
coupled to the vision controller, wherein the vision controller is
configured to send a second signal, based on a signal from the
imaging device, to the drive controller to control the movement of
the RFID tag.
28. The method as recited in claim 27, further comprising attaching
a display to the RFID reader, the display being configured to show
an image from the imaging device.
29. The method as recited in claim 27, further comprising attaching
a range finder to the RFID reader, the range finder being
configured to facilitate the definition of a boundary that can be
shown upon the display device.
30-36. (canceled)
37. The method of claim 27, further comprising providing a bar code
reader, wherein the vision controller is configured to send a
signal, based on a signal from the imaging device, to the bar code
reader when a bar code is to be read.
38. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/073,081, filed Mar. 4, 2005, which is
incorporated herein by reference in its entirety for all
purposes.
TECHNICAL FIELD
[0002] The present invention relates generally to radio frequency
identification (RFID). The present invention relates more
particularly to a method and system for aiming an RFID reader in a
manner that enhances the likelihood of reading a desired RFID tag
rather than a nearby RFID tag.
BACKGROUND
[0003] RFID tags for identifying goods are well known. They can be
applied to either the goods themselves or to packaging for the
goods. RFID tags typically comprise an integrated circuit or chip
and an antenna coupled to the chip. Information regarding the goods
is stored upon the chip. For example, this information can include
identification information, manufacturing information (such as what
manufacturing processes have already been performed and/or what
manufacturing process is to be performed next), customer
information, or shipping information. RFID tags can be formed upon
labels to facilitate their application to the goods or
packaging.
[0004] The antenna typically comprises a plurality of conductive
traces formed upon a substrate, such as the label. The antenna
facilitates communication between the chip and an RFID reader
and/or writer. Information is read from an RFID chip by first
interrogating the chip with a reader. The reader transmits a signal
that is picked up by the antenna and is then communicated to the
chip. The chip subsequently responds by communicating a signal to
the antenna that is then transmitted to the RFID reader.
[0005] The information can be read by either a hand-held RFID
reader or a stationary RFID reader. Hand-held RFID readers can be
used in warehouses, for example. In a warehouse, an RFID reader can
be used to locate a desired item (having an RFID tag) from among
many similar items.
[0006] Stationary RFID readers can be used in manufacturing
processes. For example, they can be used to determine what
manufacturing process is to be performed next on an item passing
along a conveyor. Thus, an RFID reader can be used to determine
what color an item is to be painted or what accessories are to be
added thereto. Such information can be used to determine where in a
manufacturing plant the item goes next and thus facilitates
automation of the manufacturing process.
[0007] One problem with contemporary RFID readers is that they tend
to be undesirably indiscriminate with regard to which RFID tag is
being read. Although they are somewhat directional with respect to
how the beam is transmitted therefrom, they are not completely
directional. The transmitted beam has some amount of spread and is
thus capable of reading other RFID tags that are proximate the
desired RFID tag. Generally, if an RFID reader is pointed directly
at the desired RFID tag, it is much more likely to read only that
particular RFID tag. However, if the RFID reader is slightly off
(not well aimed), then it may read a nearby RFID tag instead. Thus,
it is sometimes difficult to know which item's RFID tag is being
read.
[0008] For example, if a person is looking for an item in a
warehouse, the RFID reader may indicate the presence of the desired
item on a shelf. However, if there are other similar items nearby,
then the user may have difficulty determining which of the items is
the desired one. As such, it is desirable to provide a way to
better aim RFID readers or otherwise determine when they are
pointed at a selected RFID tag.
BRIEF SUMMARY
[0009] Systems and methods are disclosed herein to provide an RFID
reader that is capable of enhanced discrimination among nearby RFID
tags. For example, in accordance with an embodiment of the present
invention, an RFID reader is combined with an imaging device. The
imaging device is configured to facilitate aiming of the RFID
reader such that inadvertently obtaining readings from RFID tags
other than the desired RFID tag is less likely.
[0010] More specifically, in accordance with one embodiment of the
present invention an RFID reader has a built-in imaging device and
display. The display shows where the RFID reader is pointed, so
that it can more accurately be pointed only at a desired RFID tag,
while avoiding pointing it at other nearby RFID tags. This
embodiment is well suited for hand-held use.
[0011] In accordance with another embodiment of the present
invention, an RFID reader is associated with an imaging device and
machine vision is used to determine when the RFID reader is aimed
at a desired RFID tag. In this manner, manufacturing processes are
enhanced. This embodiment is well suited for stationary use.
[0012] This invention will be more fully understood in conjunction
with the following detailed description taken together with the
following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a semi-schematic side view of an exemplary
hand-held RFID reader, according to one embodiment of the present
invention;
[0014] FIG. 2 is enlarged front view of the display of FIG. 1;
[0015] FIG. 3 is a block diagram of a representative manufacturing
process that uses a stationary RFID reader, according to another
embodiment of the present invention; and
[0016] FIG. 4 is a flow chart showing the sequence of operation for
the manufacturing process of FIG. 3.
[0017] Embodiments of the present invention and their advantages
are best understood by referring to the detailed description that
follows. It should be appreciated that like reference numerals are
used to identify like elements illustrated in one or more of the
figures.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] One exemplary embodiment of the present invention is
illustrated in FIGS. 1 and 2. This exemplary embodiment is a
hand-held RFID reader assembly 20 that can be carried by a person
and used to identify goods and/or retrieve information relating to
the goods. For example, hand-held RFID reader assembly 20 can be
carried about a warehouse and used to locate goods that are to be
shipped out.
[0019] With particular respect to FIG. 1, hand-held RFID reader
assembly 20 can comprise a reader 21 having a handle 23 extending
downwardly therefrom. An imaging device 22 can be formed to reader
21 such it that images scenes in the direction that the hand-held
RFID reader assembly 20 is pointing. A display 24 can be formed to
the body such that it is readily viewable by a person holding
hand-held RFID reader 20.
[0020] Imaging device 22 can be an electronic imaging device, such
as a CCD imager. Imaging device 22 provides an output to display
24. Imaging device 22 and display 24 cooperate to define an aiming
device for hand-held RFID reader 20. Thus, by viewing display 24, a
user can determine what item reader 21 is pointed toward. It is the
RFID tag of this item that reader 21 is most likely to read.
[0021] Imaging device 22 can alternatively be an all-optical
(non-electronic) imaging device. For example, imaging device 22 can
be similar to an optical viewfinder device of a film camera.
[0022] With particular reference to FIG. 2, display 24 optionally
comprises indicia formed thereon to facilitate more accurate aiming
of reader 21. For example, display 24 can comprise crosshairs 25
and/or circular bulls eye target which is comprised of concentric
circles 26 and 27.
[0023] Optionally, the indicia can comprise a gradient, such that
display 24 becomes either lighter or darker from the center to the
outer edges thereof. For example, a dark dot can be formed at the
center of the display (such as between cross hairs 25). The dot can
define the center of a gradient that becomes lighter as the
gradient is further from the dot.
[0024] In each instance, the indicia are used to aim hand-held RFID
reader assembly 20 by helping the user to center the desired RFID
tag to be read in display 24. Thus, cross-hairs 25 may be placed
over the RFID tag and/or the RFID tag may be positioned within
inner circle 27. Such aiming of reader 21 helps to assure that
hand-held RFID reader assembly 20 is pointed at the desired item
and thus tends to mitigate the likelihood of obtaining a reading
from a nearby RFID tag.
[0025] Optionally, a range finder 28 (FIG. 1) can be used to
determine the range from imaging device 22 to the RFID tag to be
read. Range finder 28 facilitates the use of indicia that better
indicate the likelihood that a desired RFID tag will be read and
that nearby RFID tags will not be read. For example, range finder
28 can be configured to cooperate with display 24 such that indicia
formed thereon delineate a predetermined threshold of the output
power of the excitation beam of RFID reader 21.
[0026] Range finder 28 can be an active range finder, such as an
ultrasonic range finder, a microwave range finder, or a laser range
finder. Alternatively, range finder 28 can be a passive range
finder such as a split view range finder. Such passive range
finders are particularly suitable for use with all-optical imaging
devices.
[0027] More particularly, range finder 28 can cooperate with
display 24 to position cross-hairs 25, one of the circles 26 or 27,
and/or a desired portion of a gradient at the 3 dB power boundary
of a cross-section the excitation beam of RFID reader 21 in the
plane of the image (in the area of the RFID tag). That is, display
24 can provide a visual representation of the power of the
excitation beam of RFID reader 22.
[0028] For example, inner ring 26 can represent the 3 dB boundary.
Inner ring 26 would then vary in size as the distance between
imaging device 22 and the RFID tag changes, to reflect the changing
size of the 3 dB boundary. An RFID tag within this boundary is much
more likely to be read than an RFID tag outside of this boundary.
Thus, in use the goal is to aim the RFID reader assembly 20 such
that the desired RFID tag is within the boundary and all other RFID
tags are outside of the boundary.
[0029] It is worthwhile to appreciate that the use of a 3 dB power
boundary is by way of example only, and not by way of limitation.
Other power or non-power boundaries may similarly be used. The
level and/or pattern of the particular boundary used may be based
upon the readability of a tag. The readability of a tag can depend
upon the type of tag. For example, different types of tags
typically have different antennas that can affect the readability
thereof. Optionally, the user can select the level and/or pattern
of the boundary to be displayed, such as by selecting the type of
tag to be read.
[0030] Referring now to FIG. 3, another exemplary embodiment of the
present invention is shown. In this exemplary embodiment, a
stationary RFID reader assembly 50 is configured for stationary
use, such as in an assembly or test line. Stationary RFID reader
assembly 50 comprises a reader 46 having an imaging device 47
formed thereto. However, imaging device 47 can alternatively be
separate from reader 46. Indeed, imaging device 47 can be disposed
away from reader 46. For example, imaging device 47 can be several
inches, or even several feet, away from reader 46. Imaging device
47 can generally be located anywhere that facilitates imaging of
the RFID tags in a manner that enhances the ability of reader 46 to
discriminate among adjacent RFID tags.
[0031] In this instance, stationary RFID reader assembly 50 is used
in a manufacturing process to test RFID tags after bar codes have
been printed onto labels that contain the RFID tags. Optionally, a
bar code reader 42 can similarly be used to verify the printing
process by checking the bar codes that were printed upon the
labels. The use of imaging device 46 assures that both the proper
RFID tag and the proper bar code are being read.
[0032] According to this exemplary manufacturing process, a
printer/RFID writer 41 prints bar codes upon label stock 45 from
supply reel 44. The printed labels are then wound onto take-up reel
48. Label stock 45 comprises a plurality of labels. Each label
comprises an RFID tag. One or more bar codes can be printed upon
each label. The labels can be placed upon the packages of goods
that are to be shipped from a warehouse. For example, the RFID tag
can contain a unique serial number, a product or model number,
information regarding the product (such as its size, color, and
included options), and an address to which it is to be shipped. The
bar code(s), if used, can contain similar, though typically less,
information. Alpha-numeric information (text) of at least an
address can also be printed upon the label.
[0033] It is important to verify the accuracy and integrity of the
RFID tags and/or the bar codes. The RFID tags and/or the bar codes
are frequently used to route the package to its intended recipient.
Thus, verifying the accuracy and integrity of the RFID tag and/or
the bar codes can assure, among other things, that the printer/RFID
writer 41 is functioning properly and that the package is likely to
arrive at the intended location.
[0034] A printer/RFID writer 41 prints the bar codes upon the
labels and programs the RFID tags. More particularly, a print head
43 of printer/RFID writer 41 prints the bar codes and any
alpha-numeric information, while an RFID writer 40 writes the
desired information to the RFID tag of the label.
[0035] Bar code reader 42 verifies the accuracy and integrity of
bar codes printed upon the labels. Similarly, RFID reader 46
verifies the accuracy and integrity of RFID tags associated with
the labels.
[0036] When verifying the accuracy and integrity of the bar codes
and RFID tags, it is important to know which bar codes/RFID tags
are being checked. Because the individual labels are close to one
another on the label stock, it is possible to make mistakes
regarding which labels are being read. This is particularly true
for the RFID tags, since RFID reader 46 will typically be less
directional than bar code reader 42.
[0037] Imaging device 47 images the labels that pass from supply
reel 44 to take-up reel 48. A signal representative of the images
made by imaging device 47 can be provided to machine vision
controller 49. Machine vision controller 49 can be configured to
recognize when a label is disposed beneath RFID reader 46 in a
manner that mitigates the likelihood of inadvertently reading the
RFID tag of an adjacent label.
[0038] Thus, machine vision controller 49 can determine when RFID
reader 46 is to read a label. Machine vision controller 49 thus can
provide a signal to RFID reader 46 that determines when RFID reader
is to read an RFID tag. Similarly, machine vision controller 49 can
provide a signal to bar code reader 42 that determines when bar
code reader 42 is to read a bar code. Optionally, machine vision
controller 49 can provide a control signal to a drive controller 48
of printer/RFID/ writer 41 so as to control the movement of label
stock 45 with respect to bar code reader 42 and/or RFID reader 46.
Thus, according to one or more aspects of the present invention a
way is provided for determining when an RFID reader is pointed
toward a selected RFID tag, so as to mitigate the likelihood of
inadvertently reading a wrong RFID tag.
[0039] Generally, a range finder is not needed in such industrial
process applications because the distance between RFID reader 46
and the RFID tags is usually fixed. However, in applications where
this distance is not fixed, a range finder may cooperate with
machine vision controller to assure that the desired RFID tag is
within a predetermined boundary, as discussed above. For example, a
range finder may be used when scanning different sized boxes as
they move on a conveyer belt, since the different sizes can define
different ranges.
[0040] Embodiments described above illustrate, but do not limit,
the invention. It should also be understood that numerous
modifications and variations are possible in accordance with the
principles of the present invention. Accordingly, the scope of the
invention is defined only by the following claims.
* * * * *