U.S. patent application number 16/933003 was filed with the patent office on 2021-08-19 for light emitting apparatus and non-transitory computer readable medium.
This patent application is currently assigned to FUJIFILM BUSINESS INNOVATION CORP.. The applicant listed for this patent is FUJIFILM BUSINESS INNOVATION CORP.. Invention is credited to Kiyofumi AIKAWA.
Application Number | 20210256231 16/933003 |
Document ID | / |
Family ID | 1000005018808 |
Filed Date | 2021-08-19 |
United States Patent
Application |
20210256231 |
Kind Code |
A1 |
AIKAWA; Kiyofumi |
August 19, 2021 |
LIGHT EMITTING APPARATUS AND NON-TRANSITORY COMPUTER READABLE
MEDIUM
Abstract
A light emitting apparatus includes a light source, and a
processor configured to perform control to cause the light source
to blink in a blink pattern corresponding to output information
including identification information unique to the light emitting
apparatus, and configured to, when causing the light source to
blink by repeating the blink pattern, change a time interval
between the blink patterns.
Inventors: |
AIKAWA; Kiyofumi; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJIFILM BUSINESS INNOVATION CORP. |
Tokyo |
|
JP |
|
|
Assignee: |
FUJIFILM BUSINESS INNOVATION
CORP.
Tokyo
JP
|
Family ID: |
1000005018808 |
Appl. No.: |
16/933003 |
Filed: |
July 20, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06K 7/10712
20130101 |
International
Class: |
G06K 7/10 20060101
G06K007/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2020 |
JP |
2020-025120 |
Claims
1. A light emitting apparatus comprising: a light source; a
processor configured to perform control to cause the light source
to blink in a blink pattern corresponding to output information
including identification information unique to the light emitting
apparatus, and when causing the light source to blink by repeating
the blink pattern, change a time interval between a first
occurrence of the blink pattern and a second occurrence of the
blink pattern subsequent to the first occurrence of the blink
pattern; and an acceleration sensor, wherein the processor is
further configured to, when causing the light source to blink by
repeating the blink pattern, change the time interval between the
first occurrence of the blink pattern and the second occurrence of
the blink pattern when the acceleration sensor detects that the
light emitting apparatus is stationary, and make the time interval
between the blink patterns constant when the acceleration sensor
detects that the light emitting apparatus is moving.
2. The light emitting apparatus according to claim 1, wherein the
processor is configured to randomly change the time interval
between the first occurrence of the blink pattern and the second
occurrence of the blink pattern.
3. The light emitting apparatus according to claim 2, wherein the
processor is configured to set the time interval to a time period
that is n times a blink time period of the blink pattern and
randomly change the n, the n being a positive integer.
4.-6. (canceled)
7. The light emitting apparatus according to claim 1, wherein the
processor is configured to, when the acceleration sensor detects
that the light emitting apparatus is stationary, make the time
interval longer than when the acceleration sensor detects that the
light emitting apparatus is moving.
8.-12. (canceled)
13. A non-transitory computer readable medium storing a program
causing a computer included in a light emitting apparatus to
execute a process, the process comprising: performing control to
cause a light source included in the light emitting apparatus to
blink in a blink pattern corresponding to output information
including identification information unique to the light emitting
apparatus; when causing the light source to blink by repeating the
blink pattern, changing a time interval between a first occurrence
of the blink pattern and a second occurrence of the blink pattern
subsequent to the first occurrence of the blink pattern; and when
causing the light source to blink by repeating the blink pattern,
change the time interval between the first occurrence of the blink
pattern and the second occurrence of the blink pattern when an
acceleration sensor detects that the light emitting apparatus is
stationary, and make the time interval between the blink patterns
constant when the acceleration sensor detects that the light
emitting apparatus is moving.
14. A light emitting apparatus comprising: a light source; an
acceleration sensor; means for performing control to cause the
light source to blink in a blink pattern corresponding to output
information including identification information unique to the
light emitting apparatus; means for, when causing the light source
to blink by repeating the blink pattern, changing a time interval
between a first occurrence of the blink pattern and a second
occurrence of the blink pattern subsequent to the first occurrence
of the blink pattern; and means for, when causing the light source
to blink by repeating the blink pattern, changing the time interval
between the first occurrence of the blink pattern and the second
occurrence of the blink pattern when the acceleration sensor
detects that the light emitting apparatus is stationary, and making
the time interval between the blink patterns constant when the
acceleration sensor detects that the light emitting apparatus is
moving.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2020-025120 filed Feb.
18, 2020.
BACKGROUND
(i) Technical Field
[0002] The present disclosure relates to a light emitting apparatus
and a non-transitory computer readable medium.
(ii) Related Art
[0003] There is a system including plural light emitting
apparatuses and a camera. Each light emitting apparatus (also
referred to as a tag) is attached to an object, such as a person or
an item, and includes a light source that blinks in a blink pattern
corresponding to output information including unique identification
information. The camera is an apparatus that captures an image of
light rays emitted by the light sources of the plural light
emitting apparatuses. The system identifies the individual light
emitting apparatuses (individual objects) on the basis of the blink
patterns of the light emitting apparatuses appearing in an image
captured by the camera, and specifies the positions of the
individual objects. Hereinafter, this system will be referred to as
a light emitting apparatus recognition system.
[0004] Japanese Unexamined Patent Application Publication No.
2006-153828 discloses an apparatus in which an infrared generator
irradiates many tags with infrared light having an ID superimposed
thereon, and a tag having an ID identical to the ID emits
light.
[0005] Japanese Unexamined Patent Application Publication No.
2005-252399 discloses a system including an optical tag whose light
source blinks to represent a unique ID and a video camera that
captures an image of the blink of the light source. In this system,
the ID is decoded by processing a camera image obtained by the
video camera, and a light point of the optical tag included in the
camera image is tracked.
SUMMARY
[0006] In a system that recognizes a light emitting apparatus, when
two or more objects each having a light emitting apparatus attached
thereto approach each other and light rays emitted by the two or
more light emitting apparatuses appear in a small region of an
image captured by a camera, blink patterns of the individual light
emitting apparatuses may appear overlapping with each other in the
captured image and may be unrecognizable.
[0007] Aspects of non-limiting embodiments of the present
disclosure relate to, even in a case where two or more objects each
having a light emitting apparatus attached thereto approach each
other and light rays emitted by the two or more light emitting
apparatuses appear in a small region of an image captured by a
camera, making it possible to recognize blink patterns of the
individual light emitting apparatuses in the captured image.
[0008] Aspects of certain non-limiting embodiments of the present
disclosure overcome the above disadvantages and/or other
disadvantages not described above. However, aspects of the
non-limiting embodiments are not required to overcome the
disadvantages described above, and aspects of the non-limiting
embodiments of the present disclosure may not overcome any of the
disadvantages described above.
[0009] According to an aspect of the present disclosure, there is
provided a light emitting apparatus including a light source, and a
processor configured to perform control to cause the light source
to blink in a blink pattern corresponding to output information
including identification information unique to the light emitting
apparatus, and configured to, when causing the light source to
blink by repeating the blink pattern, change a time interval
between the blink patterns.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Exemplary embodiments of the present disclosure will be
described in detail based on the following figures, wherein:
[0011] FIG. 1 is a diagram illustrating a schematic configuration
of a tag recognition system according to an exemplary embodiment of
the present disclosure;
[0012] FIG. 2 is a block diagram of the tag recognition system;
[0013] FIG. 3 is a diagram illustrating an example of a case where
blink patterns of two tags do not temporally overlap each
other;
[0014] FIG. 4 is a diagram illustrating an example of a case where
blink patterns of two tags temporally overlap each other;
[0015] FIG. 5 is a diagram for describing that the image capturing
area per pixel varies according to a place;
[0016] FIG. 6 is a diagram for describing that light rays of plural
tags appear in one pixel in a frame image;
[0017] FIG. 7 is a diagram for describing identification of two
tags in a case where blink patterns of the two tags do not
temporally overlap each other;
[0018] FIG. 8 is a diagram for describing identification of two
tags in a case where blink patterns of the two tags temporally
overlap each other;
[0019] FIG. 9 is a diagram illustrating an example of time
intervals of blink patterns of tags;
[0020] FIG. 10 is a block diagram of a tag recognition system
according to another exemplary embodiment;
[0021] FIG. 11 is a diagram illustrating an example of time
intervals of blink patterns of tags according to the other
exemplary embodiment;
[0022] FIG. 12 is a block diagram of a tag recognition system
according to still another exemplary embodiment; and
[0023] FIG. 13 is a diagram illustrating an example of time
intervals of blink patterns of tags according to the related
art.
DETAILED DESCRIPTION
[0024] Hereinafter, individual exemplary embodiments of the present
disclosure will be described in detail with reference to the
attached drawings. The configurations described below are examples
for description and may be changed as appropriate in accordance
with the specifications or the like of a system, an apparatus, or a
member. In a case where there are plural exemplary embodiments,
modification examples, or the like, use of the features thereof in
appropriate combination is originally assumed. In all figures, the
same components are denoted by the same reference numerals and a
duplicate description will be omitted.
[0025] FIG. 1 is a diagram illustrating a schematic configuration
of a tag recognition system 10 according to an exemplary embodiment
of the present disclosure. The tag recognition system 10 includes
plural tags 12 and a camera 14. Each of the tags 12 is a light
emitting apparatus attached to a movable object, such as a person,
an animal, or an item, and including a light source 18 that blinks
in a blink pattern corresponding to output information including
unique identification information. The camera 14 is an apparatus
that captures an image of light rays emitted by the light sources
18 of the plural tags 12. The tag recognition system 10 also
includes a recognition apparatus 16 that identifies the individual
tags 12 on the basis of light rays emitted by the light sources 18
of the plural tags 12 and appearing in an image captured by the
camera 14 and specifies the positions of the individual tags 12.
The number of tags 12 and the number of cameras 14 are changed as
appropriate.
[0026] FIG. 1 illustrates an example in which the tag recognition
system 10 is used to manage manufacturing of printed materials. A
process of manufacturing printed materials includes a printing step
of performing printing on a medium, a post-processing step of
performing cutting, folding, or the like on a printed result (also
referred to as an intermediate 62) obtained through the printing
step, and a delivery step (not illustrated) of delivering a
post-processed result (not illustrated, also referred to as an
intermediate 62) obtained through the post-processing step. In a
printing company, various types of printed materials are
manufactured. The process to be performed varies according to a
printed material, and thus a work procedure manual 60 is managed
together with the intermediate 62. For example, there are operators
for individual steps. An operator receives the work procedure
manual 60 and the intermediate 62 from an operator of the preceding
step, processes the intermediate 62 in accordance with the work
procedure manual 60, fills out the work procedure manual 60 by hand
to indicate that the step has been completed, and transfers the set
of the work procedure manual 60 and the processed intermediate 62
to the next step. The set of the work procedure manual 60 and the
intermediate 62 may be placed in a space for in-progress items to
be processed in the next step, as illustrated in FIG. 1.
[0027] The tag recognition system 10 is used to specify the current
step or current position of each printed material. As illustrated
in FIG. 1, the tags 12 are attached to the respective work
procedure manuals 60, and the light sources 18 of the tags 12 blink
on the basis of pieces of identification information unique to the
printed materials having the tags 12 attached thereto. The camera
14 captures an image of light rays emitted by the light sources 18
of the plural tags 12, and the captured image is transmitted to the
recognition apparatus 16. The recognition apparatus 16 identifies
the individual printed materials (individual intermediates 62) on
the basis of the light rays emitted by the light sources 18 of the
individual tags 12 and appearing in the captured image, and
specifies the positions of the individual printed materials. This
usage style of the tag recognition system 10 is merely an example,
and the usage style of the tag recognition system 10 is not
limited.
[0028] FIG. 2 is a block diagram of the tag recognition system 10
according to the present exemplary embodiment. The tag recognition
system 10 includes the tag 12 serving as a light emitting
apparatus, the camera 14, and the recognition apparatus 16. The
light source 18 of the tag 12 is an infrared light emitting element
that emits an infrared ray. The camera 14 is an infrared camera
capable of capturing an image of an infrared ray emitted by the
light source 18 of the tag 12. The camera 14 includes a wide-angle
lens and is thus capable of capturing an image at 180 degrees or a
wide angle approximate to 180 degrees.
[0029] The tag 12 includes the light source 18 that blinks with an
infrared ray on the basis of identification information 26 unique
to the tag 12, a processor 20 electrically connected to the light
source 18, a memory 22 that stores a program 24 for operating the
processor 20 and the identification information 26 unique to the
tag 12, and a battery (not illustrated) that supplies power to the
individual components in the tag 12. The processor 20 reads out the
program 24 from the memory 22 and operates in accordance with the
program 24, thereby functioning as a computer. In particular, the
processor 20 operates in accordance with the program 24 to function
as a blink pattern controller 30 that performs control to cause the
light source 18 to blink in a blink pattern corresponding to output
information including the identification information 26, and a time
interval controller 32 that performs control to change the time
interval between blink patterns when causing the light source 18 to
blink by repeating the blink pattern.
[0030] The recognition apparatus 16 is connected to the camera 14
in a wired or wireless manner. The recognition apparatus 16
includes a processor 40, a shift register 42, and a memory (not
illustrated) that stores a program for operating the processor 40.
The processor 40 acquires moving images sequentially transmitted
from the camera 14 and stores, in the shift register 42, image data
of still images obtained by extracting frames from the moving
images. Hereinafter, the image data of a still image obtained by
extracting a frame from a moving image will be referred to as a
frame image. The shift register 42 temporarily stores captured
images (also referred to as captured moving images) composed of
many frame images captured by the camera 14 within a certain past
period. The processor 40 functions as a tag recognition unit 46
that reads out a captured image from the shift register 42,
interprets the blink of the light source 18 of the tag 12 appearing
in the captured image to identify the tag 12, and specifies the
position of the tag 12 on the basis of the position of light in the
captured image.
[0031] In a case where the tag recognition system 10 includes
plural cameras 14, one common recognition apparatus 16 may be
provided for the plural cameras 14. In this case, when images of
the tag 12 are captured by the plural cameras 14, the position of
the tag 12 may be specified on the basis of the positions of the
individual cameras 14 and the images captured by the individual
cameras 14.
[0032] Next, a blink pattern of the light source 18 of the tag 12
will be described. FIG. 3 is a diagram illustrating an example of a
case where blink patterns 90a and 90b of two tags 12a and 12b do
not temporally overlap each other. FIG. 4 is a diagram illustrating
an example of a case where the blink patterns 90a and 90b of the
two tags 12a and 12b temporally overlap each other. In FIG. 3 and
FIG. 4, the right-left direction represents a time axis.
[0033] As illustrated in FIG. 3, a blink pattern is formed of a
start pattern indicating the start of the blink pattern and an
identification pattern defined uniquely to each tag. The processor
20 of the tag 12 reads out start information (not illustrated) and
the identification information 26 unique to the tag 12 from the
memory 22, and encodes the start information and the identification
information 26 to generate a start pattern and an identification
pattern. That is, output information formed of the start
information and the identification information is encoded to
generate a blink pattern.
[0034] Each of the start pattern and the identification pattern is
formed by combining plural 0 or 1. 0 or 1 is represented by using
twice a frame time period (also referred to as two frame time
periods). OFF for two frame time periods of the light source 18 of
the tag 12 represents 0, and ON for two frame time periods of the
light source 18 of the tag 12 represents 1. Here, a frame time
period is a time interval of a frame image captured and acquired by
the camera 14. For example, in a case where the camera 14 acquires
30 frame images per second, the frame time period is about 33
milliseconds. The start pattern is formed of a bit string of 5 bits
that is common to the tags 12a and 12b, and the identification
pattern is formed of a bit string of 8 bits that varies between the
tags 12a an 12b. The light sources of the tags 12a and 12b are
controlled to repeatedly output the blink patterns 90a and 90b,
respectively.
[0035] The blinks of the light sources of the tags 12a and 12b are
captured by the camera 14, and the captured frame images are
sequentially transmitted to the recognition apparatus 16. As
illustrated in FIG. 3 and FIG. 4, the recognition apparatus 16
includes the shift register 42 for 26 frame images. The frame
images from the camera 14 are sequentially input to the shift
register 42.
[0036] The recognition apparatus 16 performs OR operation on two
adjacent frame images 80 stored in the shift register 42 to
generate a bitmap image 82, and generates bit unit data 43 formed
of 13 bitmap images 82. Here, the bitmap image 82 is an image
obtained by, for example, comparing the luminance values of pixels
at the same positions in the two frame images 80 and forming the
individual pixels by adopting the larger luminance values.
[0037] As described above, each of 0 (OFF) and 1 (ON) of the blink
pattern of the tag is represented by using two frame time periods
and appears in two consecutive frame images. Thus, as a result of
checking, every two frame time periods, the bit unit data 43 formed
by combining the bitmap images 82 each of which is obtained by
performing OR operation on two frame images, blink patterns of the
tags gradually appear in the bit unit data 43, as illustrated in
FIG. 7. FIG. 7 illustrates an example in which the blink pattern
90a of the tag 12a appears in a lower left portion of the bit unit
data 43 and the blink pattern 90b of the tag 12b appears in a lower
right portion of the bit unit data 43. Each bitmap image 82
constituting the bit unit data 43 is image data for one screen, and
thus a code sequence as illustrated in FIG. 7 can be obtained for
the pixels of one screen.
[0038] The tag recognition unit 46 of the recognition apparatus 16
interprets the bit unit data 43, thereby acquiring the pieces of
identification information 26 of the tags 12a and 12b and
identifying the tags 12a and 12b. The tag recognition unit 46
specifies the positions of the tags 12a and 12b on the basis of the
positions of light rays emitted by the light sources of the tags
12a and 12b and appearing in a frame image.
[0039] In some cases, light rays emitted by light sources of plural
tags may appear overlapping with each other in a frame image. FIG.
5 illustrates a state where the camera 14 is placed at a
predetermined height from a flat plane 70 and the camera 14
captures an image of light rays emitted by light sources 18a and
18b of two tags (the contours of the tags are not illustrated)
placed on the flat plane 70. At the vicinity of the center of the
lens of the camera 14 (at the portion of capturing an image of the
vicinity of the region directly below the camera 14), the distance
from the camera 14 to the flat plane 70 is short, and thus the
image capturing range on the flat plane 70 at an angle of view a of
the camera 14 is narrow. On the other hand, at the vicinity of the
edge of the lens of the camera 14 (at the portion of capturing an
image of an edge side away from the camera 14), the distance from
the camera 14 to the flat plane 70 is long, and thus the image
capturing range on the flat plane 70 at an angle of view a of the
camera 14 is wide. This means that the image capturing area per
pixel of an image capturing device of the camera 14 is small at the
vicinity of the region directly below the camera 14 and is large at
the edge side away from the camera 14.
[0040] Thus, in a case where the light sources 18a and 18b of two
tags are located close to each other at the edge side away from the
camera 14 as illustrated in FIG. 5, there is a high possibility
that the camera 14 captures an image of light rays overlapping each
other of the two light sources 18a and 18b. In a case where the
camera 14 captures an image of light rays overlapping each other,
the light rays overlapping each other of the two light sources 18a
and 18b appear in one pixel 76 in each frame image 80 forming a
captured image 84 of the camera 14 as illustrated in FIG. 6, and
thus the individual tags are not identifiable.
[0041] In addition to the case where light rays emitted by the two
light sources 18a and 18b appear overlapping with each other in the
frame image 80, there may be a case where light rays emitted by the
two light sources 18a and 18b appear in pixels close to each other
or a case where each of light rays emitted by the two light sources
18a and 18b appears in plural pixels and the parts thereof overlap
each other or close to each other. In these cases, when the frame
image 80 is processed in units of a certain number of pixels (for
example, in units of 8.times.8 pixels or 32.times.32 pixels), for
example, there is a possibility that the individual tags are not
identifiable.
[0042] In the above-described case, there are plural tags at the
edge side away from the camera 14. Also in a case where there are
plural tags directly below the camera 14, when the number of pixels
of the image capturing device of the camera 14 is small (low
resolution) or when the tags are very close to each other, light
rays emitted by the plural tags appear in the same pixel or pixels
close to each other in the frame image 80, and a similar problem
may occur.
[0043] As illustrated in FIG. 3, when a time difference Tdif
between the blink patterns 90a and 90b of the two tags 12a and 12b
is a time period corresponding to 1 bit (two frame time periods) or
longer, the two individual tags 12a and 12b are identifiable even
if the two tags 12a and 12b are located close to each other and
light rays emitted by the two light sources 18a and 18b appear in
the same pixel of a frame image. As illustrated in FIG. 7, when the
pixels of the bit unit data 43 in which light rays emitted by the
two light sources 18a and 18b appear are checked every two frame
time periods, the blink pattern 90a of the tag 12a (the code
surrounded by a broken line at the lower left in FIG. 7) appears
first and then the blink pattern 90b of the tag 12b (the code
surrounded by a broken line at the lower right in FIG. 7) appears.
Thus, the individual tags 12a and 12b are identifiable.
[0044] On the other hand, in a case where the blink patterns 90a
and 90b of the two tags 12a and 12b temporally overlap each other
as illustrated in FIG. 4, that is, in a case where the time
difference Tdif between the blink patterns 90a and 90b of the two
tags 12a and 12b is a negative value, the individual tags 12a and
12b are not identifiable when the two tags 12a and 12b are located
close to each other and light rays emitted by the two light sources
18a and 18b appear in the same pixel of a frame image. FIG. 8
illustrates a change in code sequence when the pixels of the bit
unit data 43 in which light rays emitted by the two light sources
18a and 18b appear are checked every two frame time periods at the
timings of the blink patterns 90a and 90b illustrated in FIG. 4. As
illustrated in FIG. 8, the blink pattern 90a of the tag 12a is
supposed to appear in the broken-line enclosure at the lower left.
However, in the third bit from the right indicated by "error", 0 is
replaced with 1 that is at the top of the start pattern "10001" of
the tag 12b illustrated in FIG. 4, and thus the blink pattern 90a
of the tag 12a does not appear. Also, the blink pattern 90b of the
tag 12b is supposed to appear in the broken-line enclosure at the
lower right. However, in the second and third bits from the left
indicated by "error", 00 is replaced with 11 that is at the end of
the identification pattern "01001011" of the tag 12a illustrated in
FIG. 4, and thus the blink pattern 90b of the tag 12b does not
appear. Thus, the individual tags 12a and 12b are not
identifiable.
[0045] The temporal overlap between the blink patterns 90a and 90b
of the two tags 12a and 12b illustrated in FIG. 4 continues for a
long time in the related art. As illustrated in FIG. 13, in the
related art, when the tags 12a and 12b repeatedly output the blink
patterns 90a and 90b, a blink time period Tpat of each blink
pattern 90a of the tag 12a is identical to a blink time period Tpat
of each blink pattern 90b of the tag 12b, and a time interval Tint
of the blink patterns 90a of the tag 12a is identical to a time
interval Tint of the blink patterns 90b of the tag 12b. Thus, the
blink pattern 90a of the tag 12a and the blink pattern 90b of the
tag 12b temporally overlap each other repeatedly over a long
time.
[0046] Accordingly, the tags 12 of the present exemplary embodiment
have a mechanism of operating to ensure the opportunity to
recognize the blink patterns of the individual tags 12 in an image
captured by the camera 14 even in a case where light rays emitted
by two or more tags 12 appear in a small region of the captured
image. This is realized by the processor 20 of the tag 12 (see FIG.
2) functioning as the time interval controller 32 that changes the
time interval Tint between blink patterns when causing the light
source 18 to blink so as to repeatedly output a blink pattern.
[0047] Accordingly, as illustrated in FIG. 9, an opportunity is
made in which the blink time periods Tpat of the blink patterns 90a
and 90b of the tags 12a and 12b are staggered from each other, and
an opportunity to identify the blink patterns 90a and 90b of the
tags 12a and 12b in an image captured by the camera 14 is ensured
even in a case where light rays emitted by the tags 12a and 12b
appear in a small region of the captured image.
[0048] Alternatively, the time interval controller 32 of the tag
12a (12b) may randomly change the time interval Tint between the
blink patterns 90a (90b) when causing the light source 18 to blink
so as to repeat the blink pattern 90a (90b). In this case, an
opportunity is more likely to be made in which the blink time
periods Tpat of the blink patterns 90a and 90b of the tags 12a and
12b are staggered from each other, compared to a case where the
time interval Tint between the blink patterns 90a (90b) is changed
in accordance with a certain rule.
[0049] Alternatively, the time interval controller 32 of the tag
12a (12b) may set the time interval Tint between the blink patterns
90a (90b) to a time period that is n times (n is a positive
integer) the blink time period Tpat of the blink pattern 90a (90b)
and may randomly change n. In this case, an opportunity is more
likely to be made in which the blink time periods Tpat of the blink
patterns 90a and 90b of the tags 12a and 12b are staggered from
each other, compared to a case where the time interval Tint between
the blink patterns 90a (90b) includes a time period shorter than
the blink time period Tpat of the blink pattern 90a (90b).
[0050] Next, a tag recognition system 10A according to another
exemplary embodiment will be described. FIG. 10 is a block diagram
of the tag recognition system 10A according the other exemplary
embodiment. The block diagram in FIG. 10 is different from the
block diagram in FIG. 2 in that a tag 12A includes an acceleration
sensor 50 in FIG. 10. The acceleration sensor 50 is electrically
connected to the processor 20 and outputs a detection signal to the
processor 20.
[0051] In the present exemplary embodiment, when the processor 20
of the tag 12A functions as the time interval controller 32 and
causes the light source 18 to blink so as to repeat a blink
pattern, the processor 20 changes the time interval Tint between
blink patterns when the acceleration sensor 50 detects that the tag
12A is stationary, and makes the time interval Tint between blink
patterns constant when the acceleration sensor 50 detects that the
tag 12A is moving. FIG. 11 is a diagram illustrating an example of
time intervals Tint of blink patterns 90a, 90b, and 90c of tags
12Aa, 12Ab, and 12Ac according to the present exemplary embodiment.
The tags 12Aa and 12Ab are tags detected as being stationary by the
acceleration sensor 50, and the tag 12Ac is a tag detected as
moving by the acceleration sensor 50. When the tag 12Ac is moving,
there is a high possibility that the light ray emitted by the tag
12Ac is away from the light rays emitted by the other tags 12Aa and
12Ab in an image captured by the camera 14, and there is a high
possibility that an opportunity to identify the blink pattern of
the tag 12Ac in the captured image is ensured even if the time
interval Tint between the blink patterns 90c of the tag 12Ac is not
changed. Thus, with the configuration according to the present
exemplary embodiment, it is possible to prevent an unnecessary
change in the time interval Tint between the blink patterns 90c of
the moving tag 12Ac.
[0052] In the exemplary embodiment illustrated in FIG. 10, when the
acceleration sensor 50 detects that the tag 12A is stationary, the
time interval controller 32 may set the time interval Tint between
blink patterns to be longer than when the acceleration sensor 50
detects that the tag 12A is moving. FIG. 11 illustrates the
operation with this configuration. When the tag 12Ac is moving and
the time interval Tint between the blink patterns 90c is long, the
tag 12Ac may disappear from the image capturing range of the camera
14 before the light ray emitted by the tag 12Ac appears in an image
captured by the camera 14, and it may be impossible to track the
tag 12Ac. On the other hand, when the tags 12Aa and 12Ab are
stationary, the blink patterns 90a and 90b reliably appear in an
image captured by the camera 14 even if the time interval Tint
between the blink patterns 90a and the time interval Tint between
the blink patterns 90b are long, and thus there is no concern
described above about the tag 12Ac. Thus, when the tags 12Aa and
12Ab are stationary, excessive blinks of the light sources 18 of
the tags 12Aa and 12Ab may be suppressed by setting the time
interval Tint between the blink patterns 90a and the time interval
Tint between the blink patterns 90b to be long. In addition, as a
result of setting the time interval Tint between the blink patterns
90a of the tag 12Aa and the time interval Tint between the blink
patterns 90b of the tag 12Ab to be long, the blink patterns 90a of
the tag 12Aa and the blink patterns 90b of the tag 12Ab are less
likely to temporally overlap each other. Accordingly, even in a
case where light rays emitted by the tags 12Aa and 12Ab appear in a
small region of an image captured by the camera 14, an opportunity
to identify the blink patterns 90a and 90b of the tags 12Aa and
12Ab in the captured image is ensured more reliably.
[0053] Next, a tag recognition system 10B according to still
another exemplary embodiment will be described. FIG. 12 is a block
diagram of the tag recognition system 10B according the other
exemplary embodiment. The block diagram in FIG. 12 is different
from the block diagram in FIG. 2 in that a tag 12B includes a
photodetector 52 in FIG. 12. The photodetector 52 is electrically
connected to the processor 20 and outputs a detection signal to the
processor 20.
[0054] In the present exemplary embodiment, when the processor 20
of the tag 12B functions as the time interval controller 32 and
causes the light source 18 to blink so as to repeat a blink
pattern, the processor 20 changes the time interval Tint between
blink patterns when the photodetector 52 detects light emitted by
the light source 18 of another tag, and makes the time interval
Tint between blink patterns constant when the photodetector 52 does
not detect light emitted by the light source 18 of another tag.
When the photodetector 52 of the tag 12B does not detect light
emitted by another tag, there is a high possibility that the light
emitted by the tag 12B is away from the light emitted by the other
tag in an image captured by the camera 14, and there is a high
possibility that an opportunity to identify the blink pattern of
the tag 12B in the captured image is ensured even if the time
interval Tint between the blink patterns of the tag 12B is not
changed. Thus, with the configuration described above, it is
possible to prevent an unnecessary change in the time interval Tint
between the blink patterns of the tag 12B when the photodetector 52
of the tag 12B does not detect light emitted by another tag.
[0055] In the above-described individual exemplary embodiments, the
light source 18 of the tag 12 emits an infrared ray, and the camera
14 is an infrared camera that captures an image of the light.
Alternatively, the light source 18 of the tag 12 may emit visible
light (a kind of electromagnetic wave) instead of an infrared ray,
and the camera 14 may be configured to capture an image of the
visible light.
[0056] The blink pattern output from the light source 18 of the tag
12 may be a pattern in which an end pattern follows an
identification pattern or a pattern in which a pattern for error
detection or correction is added. The type of blink pattern is not
limited.
[0057] In the above-described individual exemplary embodiments, the
tag recognition unit 46 of the recognition apparatus 16 identifies
the tag 12 in a captured image and specifies the position of the
tag 12. Alternatively, the tag recognition unit 46 may be
configured to identify the tag 12 in a captured image and not to
specify the position of the tag 12. In this specification,
"recognition of the tag (light emitting apparatus)" may include
identification of the tag in a captured image and may not include
specification of the position of the tag. The "tag recognition
system" includes a system that identifies a tag (light emitting
apparatus) in a captured image and that does not specify the
position of the tag (light emitting apparatus).
[0058] In the embodiments above, the term "processor" refers to
hardware in a broad sense. Examples of the processor include
general processors (e.g., CPU: Central Processing Unit) and
dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC:
Application Specific Integrated Circuit, FPGA: Field Programmable
Gate Array, and programmable logic device).
[0059] In the embodiments above, the term "processor" is broad
enough to encompass one processor or plural processors in
collaboration which are located physically apart from each other
but may work cooperatively. The order of operations of the
processor is not limited to one described in the embodiments above,
and may be changed.
[0060] The foregoing description of the exemplary embodiments of
the present disclosure has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the disclosure to the precise forms disclosed.
Obviously, many modifications and variations will be apparent to
practitioners skilled in the art. The embodiments were chosen and
described in order to best explain the principles of the disclosure
and its practical applications, thereby enabling others skilled in
the art to understand the disclosure for various embodiments and
with the various modifications as are suited to the particular use
contemplated. It is intended that the scope of the disclosure be
defined by the following claims and their equivalents.
* * * * *