Note: Descriptions are shown in the official language in which they were submitted.
CA 02556784 2006-08-23
RFID Reader and Range Indicating Method for the RFID Reader
FIELD OF INVENTION
[0001 ] The present invention relates to Radio Frequency Identification (RFID)
technology and more specifically to the range of an RFID reader.
BACKGROUND OF THE INVENTION
[0002] An RFID reader can read RFID tags that are within a particular range of
the
RFID reader. This range is generally a function of the RFID reader and more
particularly a function of the capabilities of the reader's antenna. Further
there may be
occasions where the read range changes during operation of the reader for
reasons that
may include the provision of reduced power to the antenna due to the power
remaining in the reader's battery. The read range of an RFID reader is also
influenced
by the "field of view" of the reader.
[0003] In current systems a user of an RFID reader must have historical
knowledge of
the reader's capability in order to guesstimate whether a particular tag,
which may be
present in a container, can be read. This process is inherently unpredictable
as the
user estimates the location of the tag and compares this to the knowledge of
the
reader's range. This unpredictability may lead to false negatives in the
reading
process where tags that are in fact present yet out of range of the reader are
falsely
determined as not being present. Further, any change in the range of the
reader during
operation will add to the unpredictability of the above process.
[0004] The operation of a typical RFID system is schematically illustrated in
Figure 1.
An RFID reader 102 has an internal antenna (not shown) that allows the RFID
reader
102 to provide an envelope 106 of RFID coverage associated with an antenna of
the
RFID reader 102. The envelope 106 represents the boundary of the RFID
coverage.
The shape of the envelope 106 is representational only and does not
necessarily reflect
the actual shape of the RFID coverage of the RFID reader 102. A first group of
RFID
tags 108 is present within the envelope 106, and will therefore be read by the
RFID
reader 102. Groups of tags 110 and 112 may possibly physically be located
quite
close to the group 108. However, if the groups 110 and 112 are located outside
the
envelope 106, they will not be read by the RFID reader 102. Thus without
knowledge
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of the coverage of the RFID reader 102, the user may falsely determine that
the tags
110 and 112 are not present.
SUMMARY OF THE INVENTION
[0005] It is an object of the invention to provide a method and system that
obviates or
mitigates at least one of the disadvantages of existing systems.
[0006] In accordance with an aspect of the present invention, there is
provided an
RFID reader, which includes an RF antenna for communicating with one or more
than
one tag using RF signals, a module for operating on the tag, a module for
analyzing a
range of the RFID reader, and a module for indicating based on the analysis a
potential area where the RFID reader is capable of implementing the operation
on the
tag.
[0007] In accordance with a further aspect of the present invention, there is
provided a
method for an RFID reader. The RFID reader includes an RF antenna for
communicating with one or more than one tag using RF signals and a module for
operating on the tag. The method includes the steps of analyzing a range of
the RFID
reader, and indicating based on the analysis a potential area where the RFID
reader is
capable of implementing the operation on the tag.
[0008] This summary of the invention does not necessarily describe all
features of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] These and other features of the invention will become more apparent
from the
following description in which reference is made to the appended drawings
wherein:
[0010] Figure 1 is a schematic diagram illustrating the operation of a typical
RFID
reader;
[0011] Figure 2 is a schematic diagram illustrating an example of an RFID
reader in
accordance with an embodiment of the present invention;
[0012] Figure 3 is a schematic diagram illustrating an example of a visual
indicator
provided by the RFID reader;
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[0013] Figure 4 is a diagram illustrating another example of the visual
indicator
provided by the RFID reader; and
[0014] Figure 5 is a flowchart illustrating the method of operating the RFID
reader in
accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
[0015] Figure 2 illustrates an example of an RFID reader in accordance with an
embodiment of the present invention. The RFID reader 120 of Figure 2 includes
an
RFID tag antenna system 122 ("Antenna" in Figure 2) and transceiver 124 for
communicating with tags 140. The RFID reader 120 may be a portal reader or a
handheld reader unit. The RFID reader 120 may have functionality of writing
information on the tags 140. The tags 140 may be read-only tags or read-write
tags.
The RFID tag antenna system 122 may include a directional antenna, an array
antenna
or an omni-directional antenna for RF signals. In the description, "RFID tag
antenna
system" and "antenna" may be used interchangeably.
[0016] The RFID reader 120 includes a controller 126 for operating the RFID
reader
120 and a memory 128 coupled to the controller 126. The RFID reader 120
further
includes a distance meter 130 and a range indicator 132. The distance meter
130 and
the range indicator 132 with the controller 126 provide to a user a visual
indicator for
indicating a potential area where the RFID reader 120 is capable of
implementing
proper operation (e.g., interrogation, read, write) on tags. The distance
meter 130 and
the range indicator 132 communicate with the controller 126. However, the
distance
meter 130 and the range indicator 132 may communicate with each other
directly.
[0017] The controller 126 is coupled to the transceiver 124 and the memory
128. The
controller 126 includes one or more than one logic processing unit, which may
include, but not limited to, one or more central processing units (CPUs),
digital signal
processors (DSPs), application-specific integrated circuits (ASIC), or
combinations
thereof.
[0018] The memory 128 includes a random access memory (RAM) and a read-only
memory (ROM). The memory 128 includes instructions and data for initializing
and
operating the RFID reader 120, such as, communication with the tags 140,
reading
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data from the tags 140, writing data on the tags 140, communication with an
external
device 142, and the operation of the distance meter 130 and the range
indicator 132.
The memory 128 may include flash memory, erasable programmable read-only
memory (EROPM), electronically erasable programmable read-only memory
(EEPROM), or combinations thereof.
[0019] The RFID reader 120 may include an interface 136 for communicating with
the external device 142 other than tags, such as a computer system, in a
wireless or
wired network. The external device 142 may include, for example, a display for
displaying visual information on a screen.
[0020] In Figure 2, all elements in the RFID reader 120 are illustrated
separately.
However, some or all of these blocks can be monolithically integrated onto a
single
chip.
[0021 ] The visual indicator is described in detail. The visual indicator
provides to the
user an indication that a candidate object(s) is partially or entirely within
the coverage
area of the antenna 122. Based on the visual indicator, the user can determine
that the
RFID reader 102 is appropriately positioned to operate on possible tags in the
candidate object. The candidate object may be a container or a box and
possibly
contain tags. In the description, the terms "candidate object" and "target
object" are
used interchangeably.
[0022] The visual indicator is a multi-dimensional illumination. The multi-
dimensional illumination may have, but not limited to, a rectangular shape
pattern, a
circular shape pattern, or an oval shape pattern. The dimension of the visual
indicator
at a distance from the RFID reader 120 is associated with the coverage area of
the
antenna 122 at that distance.
[0023] The distance meter 130 measures a distance between the RFID reader 120
and
the candidate object. The distance meter 130 may measure a straight-line
distance
between the RFID reader 120 and the candidate object. The distance meter 130
may
be an electronic distance meter, an electromagnetic distance meter, an optical
distance
meter or a laser distance meter. The distance meter 130 may repeatedly measure
the
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distance between the RFID reader 120 and the candidate object and calculate
the most
possible distance.
[0024] The result of the distance measurement is provided to the controller
126. The
controller 126 includes an analyzer 134 for analyzing the measured distance
and the
range of the RFID reader 120. The analyzer 134 may analyze the range of the
RFID
reader 120 in parallel to the distance measurement or separately from the
distance
measurement.
[0025] The analyzer 134 determines whether the candidate object is within the
range
of the RFID reader 120. The analyzer 134 determines one or more than one
dimension of the visual indicator on the candidate object (i.e., the
dimensions of an
illuminated area on the candidate object). The dimensions of the visual
indicator are
associated with the dimensions of the potential area on the candidate object.
[0026] For example, when the RFID reader 120 uses a rectangular shaped visual
indicator pattern, the analyzer 134 determines the width and height of that
rectangle.
Similarly, when the RFID reader 120 uses a circular shaped visual indicator
pattern,
the analyzer 134 determines the radius of that circle.
[0027] The dimension of the visual indicator at the position of the candidate
object is
determined by some function of the distance to the candidate object and the
RFID
reader's capabilities, such as, but not limited to, configured power output,
possibly
some environmental conditions, or a combination thereof. The environmental
conditions may include, but not limited to, temperature and humidity etc. The
controller 126 calibrates the range indicator 132 based on the result of the
analysis.
The range indicator 132 may directly communicate with the distance meter 130
for
this operation.
[0028] The range indicator 132 is calibrated based on the measured distance
and the
current range of the RFID reader 120. For example, depending on the distance,
the
candidate object may be completely illuminated or not be illuminated. The
dimension
of the visual indicator may be changed due to the read range changes during
operation
of the RFID reader 120.
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[0029] The range indicator 132 includes a multi-dimension projector for
projecting
the multi-dimensional illumination. The multi-dimension projector may be, but
not
limited to, an IR emitter, a laser light emitter, an array of LEDs etc. The
range
indicator 132 may include, for example, a 2-dimensinoal projector for
providing a 2-
dimensional visual image (e.g., rectangular image). The range indicator 132
may
utilize a multi-dimensional barcode scanner technique to project a multi-
dimensional
illumination pattern (i.e., visual indicator) on the candidate object. The 2-
dimensional
projector may include a projecting module of a 2-dimensional barcode scanner,
which
quickly provides a laser both vertically and horizontally to display the
illumination
pattern. The range indicator 132 may include a source for the visual
indicators, which
may, but not limited to, a laser, halogen, LED. The range indicator 132 may be
a
multicolor projector that changes color based on the analysis.
[0030] The range indicator 132 may further include a feedback device for
providing
feedback to user, other than visual indicators. The feedback device may
include, but
not limited to, a device for generating audible signals (e.g., beep), a device
for
generating readable message on a display (e.g., 152 of Figure 3), and a device
for
generating vibrations. The sound device may include, but not limited to, a
buzzer,
speaker or other simple audible output device. The feedback device operates
when
the candidate object is outside the range of the RFID reader 120. However, the
feedback device may provide the indicator when the candidate object is within
the
range of the RFID reader 120. The feedback device may be included in any
elements
of the RFID reader 120 other than the range indicator 132. The external device
142
may include the feedback device.
[0031 ] Figure 3 illustrates an example of a visual indicator provided by the
RFID
reader. The RFID reader 120A of Figure 3 is same or similar to the RFID reader
120
of Figure 2, and includes the distance meter 130 and the range indicator 132
of Figure
2. The RFID reader 120A includes a display 152 for displaying visual
information on
a screen, a plurality of keypads 154 for inputting information into the RFID
reader
120A, and a projector device 156. The projector device 156 is an element of
the range
indicator 132. In Figure 3, "158" represents an envelope of the RFID coverage.
The
shape of the envelope 158 is representational only and is not limited to that
shown in
Figure 3. In Figure 3, "170" represents a visual indicator at the position of
a candidate
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object 160, and is associated with the envelope 158 of the RFID coverage. In
Figure
3, "172" represents an illumination for the visual indicator 170, and is
projected from
the RFID reader 120A. The illumination 172 may be visible and may be a visual
indicator.
[0032] In this example, the RFID reader 120A determines that the candidate
container
160 is within the range of the RFID reader 120A, and illuminates a 2-
dimensional area
on the surface of the candidate container 160 by the visual indicator 170.
[0033] For example, as shown in Figure 3, if the candidate container 160 is
completely illuminated, the user of the RFID reader 120A can determine that
most or
all tags contained within the container 160 will be read. Further, the visual
indicator
170 or the illumination 172 provides an indication on whether any possible
tags
within the area between the RFID reader 120A and the candidate object 160 will
be
properly readable. The user may determine that any tags within the distance to
the
candidate object 160 are not positioned for proper operation of the RFID
reader 120A
by reviewing the visual indicator 170 or illumination 172.
[0034] Figure 4 illustrates another example of the visual indicator on the
candidate
object provided by the RFID reader 120A. In Figure 4, "180" represents an
illuminated area on the candidate object 160 and also represents the visual
indicator
on the candidate object 160, both of which are associated with the envelope
(not
shown) of the RFID coverage. In Figure 4, "182" represents an illumination for
the
visual indicator 180, and is projected from the RFID reader 120A. The
illumination
182 may be visible and may be a visual indicator.
[0035] In this example, an upper area in one surface of the candidate
container 160 is
illuminated. Thus, the upper area of the candidate container 160 is in the
range of the
RFID reader 120A, and the lower area of the candidate container 160 is not in
the
range of the RFID reader 120A. Any tags in the lower area of the candidate
container
160 will not be readable.
[0036] Further, the visual indicator 180 or the illumination 182 provides an
indication
on whether any possible tags within the area between the RFID reader 120A and
the
candidate object 160 will be properly readable. The user may determine that
any tags
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within the distance to the candidate object 160 are not positioned for proper
operation
of the RFID reader 120A by reviewing the visual indicator 180 or the
illumination
182.
[0037] In Figures 3-4, one surface of the candidate container 160 is partially
or
entirely illuminated. However, if the candidate container 160 is not
illuminated, the
user of the RFID reader 120A can determine that the container 160, the RFID
reader
120A, possible tags within the container 160 are not positioned for proper
interrogation, read, or write operation of the RFID reader 120A.
[0038] Figure 5 illustrates an example of the method of operating the RFID
reader in
accordance with an embodiment of the present invention. At step 200, the read
range
R of the RFID reader (e.g., 120 of Figure 2, 120A of Figures 3-4) is
determined. At
step 202, a distance between the RFID reader and a candidate object (e.g.,
container,
box) is determined (130 of Figure 2). At step 204, it is determined whether
the
candidate object is within the read range R of the RFID reader. At step 204,
the
dimension of an illuminated area is also determined. If the candidate object
is within
the read range R of the RFID reader, the range indicator (132 of Figure 2) is
calibrated, and projects the illuminated area at step 206. If the candidate
object is not
within the read range R of the RFID reader, a user receives a feedback (step
208),
such as beep, readable message, or indicator led.
[0039] In Figure 5, the step of determining the read range R of the RFID
reader (step
202) is implemented after the step of determining the distance to the
candidate object
(step 202). However, the step 202 may is implemented prior to step 200. As
described above, the range R of the RFID reader may be determined in parallel
to the
distance measurement or separately from the distance measurement.
[0040] According to the above embodiments, the user of the RFID reader can
determine that a candidate object which may have tags are located within the
range of
the RFID reader for proper interrogation, read or write operation. In
dependence upon
the visual indicator, the user can relocate the RFID reader or objects that
may contain
tags.
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[0041] The above embodiments are described using the candidate object
containing
possible tags. However, in a further embodiment, tags may be attached to the
surface
of the candidate object.
[0042] In a further embodiment, the candidate object is a tag itself or a
group of tags.
In this embodiment, the visual indicator provides to a user an indication that
the tag or
the group of tags are within the range of the RFID reader and are properly
read by the
RFID reader.
[0043] The above embodiments of the invention may be implemented in one or any
combination of hardware, firmware, and software. The invention may also be
implemented as instructions contained in or on a machine-readable medium,
which
may be read and executed by one or more processors to perform the operations
described herein. A machine-readable medium may include any mechanism for
storing, transmitting, and/or receiving information in a form readable by a
machine
(e.g., a computer). For example, a machine-readable medium may include a
storage
medium, such as but not limited to read only memory (ROM); random access
memory
(RAM); magnetic disk storage media; optical storage media; a flash memory
device,
etc. A machine-readable medium may also include a propagated signal which has
been modulated to encode the instructions, such as but not limited to
electromagnetic,
optical, or acoustical carrier wave signals.
[0044] The present invention has been described with regard to one or more
embodiments. However, it will be apparent to persons skilled in the art that a
number
of variations and modifications can be made without departing from the scope
of the
invention as defined in the claims.
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