U.S. patent application number 12/461223 was filed with the patent office on 2009-12-03 for illuminative light communication device and lighting device.
This patent application is currently assigned to Nakagawa Laboratories, Inc.. Invention is credited to Shinichiro Haruyama, Toshihiko Komine, Masao Nakagawa.
Application Number | 20090297167 12/461223 |
Document ID | / |
Family ID | 32180882 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090297167 |
Kind Code |
A1 |
Nakagawa; Masao ; et
al. |
December 3, 2009 |
Illuminative light communication device and lighting device
Abstract
In the case of performing communication by using illumination
light when the illumination is on, switches are turned on, a signal
modulated in an optical modulation part in accordance with
information is superposed to a power waveform for the illumination
with a power distributor and the illumination 16 is driven in a
modulated state. When the illumination is off, the switches are
turned off, a switch is turned on and a communication part is
driven in a modulated state by the optical modulation part. The
communication part can be constituted so as to include an infrared
light emitting element part to perform infrared communication when
the illumination is off. Consequently communication can be
performed not only when the of illumination is on but also when the
lighting is kept off. The communication device can be constituted
of one element integrating the illumination part and the
communication part, so that a compact system can be
constituted.
Inventors: |
Nakagawa; Masao; (Kanagawa,
JP) ; Komine; Toshihiko; (Shizuoka, JP) ;
Haruyama; Shinichiro; (Kanagawa, JP) |
Correspondence
Address: |
RADER FISHMAN & GRAUER PLLC
LION BUILDING, 1233 20TH STREET N.W., SUITE 501
WASHINGTON
DC
20036
US
|
Assignee: |
Nakagawa Laboratories, Inc.
Tokyo
JP
|
Family ID: |
32180882 |
Appl. No.: |
12/461223 |
Filed: |
August 5, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10532250 |
Sep 29, 2005 |
7583901 |
|
|
PCT/JP2003/013539 |
Oct 23, 2003 |
|
|
|
12461223 |
|
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Current U.S.
Class: |
398/182 |
Current CPC
Class: |
H04B 10/1141 20130101;
F21K 9/65 20160801; F21V 33/0052 20130101; H04B 3/54 20130101; F21K
9/20 20160801; H05B 47/19 20200101; H04B 2203/5458 20130101; H04B
10/116 20130101; H01L 2924/3025 20130101; H05B 47/185 20200101;
H01L 2224/48247 20130101; F21Y 2115/10 20160801; H05B 47/195
20200101; G09F 9/33 20130101; H01L 2224/48091 20130101; H04B
2203/5412 20130101; H01L 25/0753 20130101; H04B 10/1149 20130101;
H01L 2224/48091 20130101; H01L 2924/00014 20130101; H01L 2224/48091
20130101; H01L 2924/00 20130101; H01L 2924/3025 20130101; H01L
2924/00 20130101 |
Class at
Publication: |
398/182 |
International
Class: |
H04B 10/04 20060101
H04B010/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 24, 2002 |
JP |
2002-309557 |
Dec 4, 2002 |
JP |
2002-352075 |
Jan 10, 2003 |
JP |
2003-004560 |
Feb 17, 2003 |
JP |
2003-037746 |
Mar 14, 2003 |
JP |
2003-070673 |
Mar 25, 2003 |
JP |
2003-082278 |
Mar 26, 2003 |
JP |
2003-084819 |
Jun 6, 2003 |
JP |
2003-161859 |
Jun 23, 2003 |
JP |
2003-177816 |
Sep 16, 2003 |
JP |
2003-323052 |
Claims
1. An illuminative light communication device, comprising: a
lighting unit that emits light for lighting; a modulator that
controls blinking or light intensity of the lighting unit in
accordance with data, thereby modulating the emitted light; a
communicating unit that transmits the data through optical
communication other than illuminative light communication; and a
switching unit that changes over respective operations of the
modulator and the communicating unit based on whether the lighting
unit is on or off; wherein the switching unit changes over such
that the communicating unit can operate while the lighting unit is
off.
2. The illuminative light communication device according to claim
1, wherein the communicating unit transmits data through infrared
light communication.
3. The illuminative light communication device according to claim
2, wherein: the lighting unit comprises a plurality of LED devices;
the LED devices comprise an infrared light emitting device that can
selectively emit infrared light; and the infrared light emitting
device is used as the communicating unit.
4. An illuminative light communication device, comprising: a
lighting unit that emits light for lighting; and a modulator that
controls blinking or light intensity of the lighting unit in
accordance with data, thereby modulating the emitted light; wherein
in response to an on-switching instruction, the modulator modulate
in accordance with the data while supplying sufficient electric
power for lighting to the lighting unit, while in response to an
off-switching instruction, the modulator modulate in accordance
with the data to allow the lighting unit to blink a number of times
necessary for communication.
5. A lighting device for emitting illuminative light, comprising:
an illuminative light emitting device that emits white light for
lighting; and an infrared light emitting device that emits infrared
light for infrared data communication.
6. The lighting device according to claim 5, wherein the
illuminative light emitting device is controlled for modulation to
carry out illuminative light communication independently of the
infrared light emitting device.
7. The lighting device according to claim 5, wherein the
illuminative light emitting device comprises a red, a blue, and a
green light emitting device, and the infrared light emitting device
is arranged along with each light emitting device.
8. The lighting device according to claim 5, wherein the
illuminative light emitting device comprises a blue or an
ultraviolet light emitting device and fluorescer that is provided
surrounding the light emitting device.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/532,250 filed Oct. 23, 2003, as
International Application No. PCT/JP03/013539, now pending, the
contents of which, including specification, claims and drawings,
are incorporated herein by reference in their entirety. This
application claims priority from Japanese Patent Application Serial
No. 2003-070673 filed Mar. 14, 2003, the contents of which are
incorporated herein by reference in their entireties.
BACKGROUND OF THE INVENTION
[0002] The present invention aims to provide an illuminative light
communication device, which allows communication even without
lighting and effectively utilizes infrared light data
communication, and a lighting device preferable for such
illuminative light communication device.
[0003] According to such objective, the illuminative light
communication device includes a lighting unit that emits light for
lighting, a modulator that controls blinking or light intensity of
the lighting unit in accordance with data, thereby modulating the
emitted light, a communicating unit that transmits the data through
optical communication other than illuminative light communication,
and a switch that changes over respective operations of the
modulator and the communicating unit based on whether the lighting
unit is on or off. The switch changes over such that the
communicating unit can operate while the lighting unit is off. The
communicating unit may be structured so as to transmit data through
infrared light data communication.
[0004] As described above, in addition to illuminative light
communication that is made possible by the lighting unit outputting
illuminative light modulated by the modulator, illuminative light
communication is carried out while the lighting unit is on, using a
conventional communication unit such as infrared light
communication unit. On the other hand, without lighting,
communication is carried out using a communication unit such as
infrared light data communication. This allows continuous
communication even without lighting.
[0005] Note that when carrying out infrared light data
communication, an infrared light emitting device that can
selectively emit infrared light can be included in multiple LED
devices in the lighting unit. As a result, it is unnecessary to
separately provide another communicating unit to be used without
lighting, and an indoor lighting unit that is deployed so as to
prevent generation of a shadow can be used for infrared light data
communication. This allows reduction in influences of shadowing,
and stable infrared light data communication.
[0006] An illuminative light communication device includes a
lighting unit that emits light for lighting and a modulator that
controls blinking or light intensity of the lighting unit in
accordance with data, thereby modulating the emitted light. In
response to an on-switching instruction, the modulator modulates in
accordance with the data while supplying sufficient electric power
for lighting to the lighting unit while in response to an
off-switching instruction, the modulator modulates in accordance
with the data to allow the lighting unit to blink a number of times
necessary for communication.
[0007] This structure allows communication with lighting with
sufficient light intensity for lighting, and communication using
emitted light only required for the communication when light
intensity is unnecessary or without lighting. As a result, users
can turn the lighting either on or off, and optical communication
is possible even without lighting.
[0008] Furthermore, a lighting device for emitting illuminative
light includes an illuminative light emitting device that emits
white light for lighting and an infrared light emitting device that
emits infrared light for infrared data communication. The
illuminative light emitting device can be controlled for modulation
to carry out illuminative light communication independently of the
infrared light emitting device. This allows illuminative light
communication with lighting by illuminative light emitted from the
illuminative light emitting device, and infrared light data
communication without lighting by infrared light emitted from the
infrared light emitting device. As a result, communication is
possible even without lighting, although communication could not be
carried out through conventional illuminative light communication
without lighting. In addition, an additional communicating unit is
not needed for infrared light data communication, influences of
shadowing can be reduced and stable infrared light data
communication can be carried out, thereby increasing the
possibility of infrared light data communication.
[0009] Note that the lighting device can be structured of a red, a
blue, and a green light emitting device in line with the infrared
light emitting devices. Alternatively, it may be structured of
infrared light emitting devices in line with illuminative light
emitting devices, which are made up of a blue or an ultraviolet
light emitting device and fluorescer provided surrounding the light
emitting devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a block diagram of an illuminative light
communication device, according to a first embodiment of the
present invention;
[0011] FIG. 2 is a table describing exemplary operations defined
according to respective combinations of an ON and an OFF status of
switches 12 through 14;
[0012] FIG. 3 is a schematic diagram of an exemplary lighting
element, according to the present invention, which is preferable to
being used for the illuminative light communication device,
according to the present invention;
[0013] FIG. 4 is a diagram describing an application of an
exemplary lighting element, according to the present invention, to
the illuminative light communication device, according to the
present invention;
[0014] FIG. 5 is a schematic diagram of another exemplary lighting
element, according to the present invention, which is preferable to
being used for the illuminative light communication device,
according to the present invention;
[0015] FIG. 6 is a diagram describing another application of an
exemplary lighting element, according to the present invention, to
the illuminative light communication device, according to the
present invention;
[0016] FIG. 7 is a block diagram of an illuminative light
communication device, according to a second embodiment of the
present invention; and
[0017] FIGS. 8A-8B each is a diagram of an exemplary structure of a
typical white LED; FIG. 8A shows an exemplary structure using three
color light emitting elements; and FIG. 8B shows an exemplary
structure using fluorescer.
DETAILED DESCRIPTION OF THE INVENTION
[0018] FIG. 8 is a diagram of a configuration of an exemplary
typical white LED. In the drawing, 331 and 341 denote LED devices,
332 denotes a red light emitting element, 333 denotes a green light
emitting element, 334 denotes a blue light emitting element, 342
denotes a light emitting element, and 343 denotes fluorescer. An
exemplary white LED shown in FIG. 8A is configured such that the
red light emitting element 332, the green light emitting element
333, and the blue light emitting element 334 are arranged in the
LED device 331. White light can be seen when red, green, and blue
light emitted from respective light emitting elements are
mixed.
[0019] In the case of an exemplary white LED shown in FIG. 8B, a
blue or an ultraviolet light emitting element 342 is provided in
the LED device 341, and the fluorescer 343 is provided surrounding
the light emitting element 342. As with a fluorescent lamp, the LED
device 341 has the fluorescer 343, which emits white light when
blue light or ultraviolet light emitted from the light emitting
element 342 is irradiated on the fluorescer 343. As a result, white
light is emitted.
[0020] Since such single LED device has less light intensity for
lighting, an LED array made up of multiple LED devices is typically
used. In the following description, the LED array may be referred
to as just LED. Such LED array is used for some traffic control
signals, rear lamps of an automobile, desk lamps, and foot lights,
for example. The features of LEDs are longer life, smaller size,
and lower power consumption than those of conventional illuminative
light sources such as incandescent lamps and fluorescent lamps.
Accordingly use of LEDs as a future illuminative light source is
considered.
[0021] In addition, another feature of light emitting elements such
as LEDs is a very fast response speed since a preheating time is
unnecessary. Paying attention to those features such as a fast
response speed and electrical controllability, a study of
superimposing a signal on an illuminative LED light and thereby
transferring the signal has been conducted.
[0022] Lighting elements are often provided on the ceiling or a
wall surface, or a pole is set up to irradiate a certain area from
above, thereby preventing generation of a shadow. Typically,
wireless communication including optical communication has a
problem of shadowing which causes decrease in signal intensity and
disturbance in communication behind an object. However, since
lighting elements are often provided so as to prevent shadowing as
described above, this means that illuminative light communication
is possible without development of shadowing. In addition, there is
an advantage that high communication quality is ensured using a
high electric power for lighting.
[0023] However, use of illuminative light develops a problem that
illuminative light communication cannot be carried out without
lighting. Lights may be kept on even when unnecessary. However,
users may not appreciate keeping lights turned on when unnecessary
in view of energy conservation, or lighting may be prohibited at
night, for example. There is a problem that communication cannot be
carried out without lighting and cannot be carried out when
unattended, at night, or while using a projector.
[0024] On the other hand, infrared light communication has been
widely used, and standardization has been carried out by the
infrared data association (IrDA) or the like. There is fear that
infrared light communication may adversely influence the human body
such as eyes. As a result, it is impossible to carry out high
electric power communication. In addition, it is characterized in
that it is easily influenced by shadowing, which causes decrease in
communication quality due to characteristics of light when an
obstruction such as a user exists. From these reasons, an available
range is limited, and that communication may not be stably carried
out.
[0025] To solve such problems, a communication device with the
following structure uses illuminative light and infrared light
together and is available even without lighting.
[0026] FIG. 1 is a block diagram of an illuminative light
communication device, according to a first embodiment of the
present invention. In the drawing, 311 denotes an optical
modulator, 312 through 314 denote switches, 315 denotes an electric
power divider, 316 denotes a lighting unit, 317 denotes a
communicating unit, 321 denotes a data terminal, and 322 denotes a
light receiving unit. A light source which emits light for lighting
is provided in the lighting unit 316. Since a semiconductor light
emitting element capable of operating at a fast response speed such
as a white LED is used as a light source, illuminative light
communication is possible by controlling blinking and/or light
intensity. In addition, the communicating unit 317 may transmit
data using an optical communication method other than illuminative
light communication such as infrared light communication. Note that
the lighting unit 316 and the communicating unit 317 may be
deployed in the same device to be described later. Needless to say,
those may be formed separately.
[0027] The optical modulator 311 and the electric power divider
315, which are used as a modulation means according to the present
invention, modulate illuminative light by controlling blinking
and/or light intensity of the lighting unit 316 in conformity with
data. In this exemplary structure, the optical modulator 311
modulates received data using a predetermined modulation method,
superimposes the resulting modulated data on an electric power
waveform, and then transmits the resulting superimposed data
waveform to the electric power divider 315 via the switch 313 or to
the communicating unit 317 via the switch 314. This allows control
of light intensity and on/off control of the lighting unit 316 and
the communicating unit 317.
[0028] The electric power divider 315 mainly supplies electric
power to the lighting unit 316. When an electric power superimposed
with modulated data to be transmitted from the optical modulator
311 via the switch 313 is supplied, this electric power is supplied
to the lighting unit 316.
[0029] The switches 312 through 314, which are switching means of
the present invention, are turned on or off in conformity with an
external command for turning on or off. The switch 312 allows or
prohibits electric power supply to the electric power divider 315,
thereby turning lights on or off. The switch 313 allows or
prohibits provision of the modulated data to the electric power
divider 315, thereby allowing or prohibiting transmission of data
via illuminative light (illuminative light communication) while the
lighting unit 316 is illuminating. The switch 314 allows or
prohibits transmission of the modulated data to the communicating
unit 317. Note that either the switch 312 or the switch 313 is
turned on or both of them are turned off at the same time.
[0030] FIG. 2 is a table describing exemplary operations defined
according to respective combinations of an on and an off status of
the switches 312 through 314. When the switch 312 is on, the switch
313 is off, and the switch 314 is on, the communicating unit 317
carries out communication while the lighting unit 316 is
illuminating as shown in FIG. 2 (1). Note that in FIG. 2,
communication by the communicating unit 317 is described as
`infrared light communication`, but the present invention is not
limited to this. When setting of the switches 312 and 313 is the
same as that just described, and the switch is off, only lighting
is carried out without carrying out communication as shown in FIG.
2 (2). In this case, illuminative light is not used for
communication. When the switch 312 is off, the switch 313 is on,
and the switch 314 is on, as shown in FIG. 2 (3), the lighting unit
316 carries out lighting and illuminative light communication, and
the communicating unit 317 also carries out data communication. In
this configuration, when the switch 314 is off, the lighting unit
316 carries out lighting and illuminative light communication as
shown in FIG. 2 (4). When both switches 312 and 313 are off, the
lighting unit 316 is not used. In this configuration, when the
switch 314 is on, the communicating unit 317 carries out data
communication as shown in FIG. 2 (5). Otherwise, when the switch
314 is off, neither lighting nor communication is carried out as
shown in FIG. 2 (6).
[0031] For example, in the case of carrying out communication when
lighting is needed, data communication by the communicating unit
317 or illuminative light communication by the lighting unit 316
may be carried out by turning the switch 312 on, the switch 313
off, and the switch 314 on as shown in FIG. 2 (1), or turning the
switch 312 off, the switch 313 on, and the switch 314 either on or
off as shown in FIG. 2 (3) or FIG. 2 (4). On the other hand, when
lighting is unnecessary, data communication by the communicating
unit 317 is carried out by turning both switches 312 and 313 off,
and the switch 314 on as shown in FIG. 2 (5).
[0032] As described above, illuminative light communication with
lighting is possible, and communication without lighting is also
possible. When infrared light communication is used as a
communication method for the communicating unit 317 as described
above, since infrared light is invisible, a person cannot sense the
brightness during communication. Therefore, communication can be
carried out even without lighting.
[0033] FIG. 3 is a schematic diagram of an exemplary lighting
element, according to the present invention, which is preferable to
be used for the illuminative light communication device, according
to the present invention. FIG. 4 is a diagram describing an
exemplary application of the lighting element, according to the
present invention, to the illuminative light communication device,
according to the present invention. In the drawing, the same
symbols are given to the same parts as those in FIG. 8, and
repetitive descriptions thereof are thus omitted. 335 denotes an
infrared light emitting element. As shown in FIG. 8, needless to
say, typical LEDs for lighting emit only visible lights, and do not
emit infrared light. Accordingly, in the case of carrying out
infrared light communication by the communicating unit 317 as
described above, an infrared light LED must be additionally
provided as the communicating unit 317. Needless to say, different
LEDs may be used in the lighting unit 316 and the communicating
unit 317. Alternatively, since both LEDs have similar structures,
they can be integrated into one. An example of this case is shown
in FIG. 3.
[0034] In the example shown in FIG. 3, the infrared light emitting
element 335 is provided in an LED which emits white light by mixing
red, green, and blue emitted lights as shown in FIG. 8A. Even
though the infrared light emitting element 335 is provided in this
manner, the package size is several millimeters wide and several
millimeters high, which is almost the same as that of typical
LEDs.
[0035] To use such lighting element in an illuminative light
communication device, as shown in FIG. 4, the red light emitting
element 332, the green light emitting element 333, and the blue
light emitting element 334 are electrically connected to the
electric power divider 315 so as to receive electric power with
lighting or modulated electric power during illuminative light
communication. In addition, the infrared light emitting element 335
is connected to the optical modulator 311 via the switch 314,
allowing the optical modulator 311 to modulate and drive the
infrared light emitting element 335 when the switch 314 is turned
on. Furthermore, a shared electrode may be grounded along with the
optical modulator 311 and the electric power divider 315.
[0036] For ordinary lighting, a visible white illuminative light is
emitted by mixing three color lights emitted from the red light
emitting element 332, the green light emitting element 333, and the
blue light emitting element 334. High-speed modulation of this
illuminative light allows illuminative light communication. In
addition, light emitted from the infrared light emitting element
335 is invisible. However, high-speed modulation of light to be
emitted allows wireless communication using invisible infrared
light.
[0037] As described above, illuminative light communication by
carrying out high-speed modulation of respective lights emitted
from the red light emitting element 332, the green light emitting
element 333, and the blue light emitting element 334, and infrared
light communication by carrying out high-speed modulation of light
emitted from the infrared light emitting element 335 can be changed
over by changing settings of the switches 312 through 314 as
described above. For example, when both lighting and communication
are required, the red light emitting element 332, the green light
emitting element 333, and the blue light emitting element 334 are
operated to emit respective lights, and at the same time the
emitted lights are modulated at a high speed, thereby transmitting
data. As a result, since an optical power needed for lighting may
also be used for communication, high-speed and high-quality
communication can be carried out. In addition, when lighting is
unnecessary but communication is required, communication is carried
out by modulating and driving the infrared light emitting element
335 and operating it to emit infrared light. In this case, since
infrared light is invisible, communication can be carried out even
without lighting. In addition, typically, since people are often
absent when lights are off, adverse influences on the human body
such as eyes can be decreased.
[0038] Needless to say, infrared light communication may also be
carried out with lighting, by modulating and driving the infrared
light emitting element 335. In this case, what should be done on a
receiver side is to receive only infrared light, and there is no
need to deal with multiple wavelengths, allowing provision of a
simplified structure.
[0039] Alternatively, communication using both illuminative light
and infrared light may be carried out by modulating and driving
respective lights from the red light emitting element 332, the
green light emitting element 333, the blue light emitting element
334, and also modulating and driving light from the infrared light
emitting element 335. In this case, since all power is available,
higher-speed and higher-quality communication than that using the
aforementioned methods is possible.
[0040] Note that since the red light emitting element 332, the
green light emitting element 333, the blue light emitting element
334, and the infrared light emitting element 335 in the
configuration shown in FIG. 3 may be driven independently, multiple
pieces of data can be transmitted at the same time by dividing
wavelengths.
[0041] FIG. 5 is a schematic diagram of another exemplary lighting
element, according to the present invention, which is preferable to
be used for the illuminative light communication device according
to the present invention. FIG. 6 is a diagram describing another
application of an exemplary lighting element, according to the
present invention, to the illuminative light communication device
according to the present invention. In the drawing, the same
symbols are given to the same parts as those in FIG. 8, and
repetitive descriptions thereof are thus omitted. 344 denotes an
infrared light emitting element. In the example shown in FIG. 5,
the infrared light emitting element 344 is provided in the LED
device 341 structured as shown in FIG. 8B.
[0042] To use such a lighting element in the illuminative light
communication device, as shown in FIG. 6, the light emitting
element 342 is electrically connected to the electric power divider
315 and receives electric power with lighting, and receives
modulated power during illuminative light communication. In
addition, the infrared light emitting element 335 is electrically
connected to the optical modulator 311 via the switch 314, allowing
the optical modulator 311 to modulate and drive the infrared light
emitting element 335 while the switch 314 is turned on.
Furthermore, a shared electrode may be grounded along with the
optical modulator 311 and the electric power divider 315.
[0043] For ordinary lighting, white light is emitted by irradiating
the fluorescer 343 with blue light or ultraviolet light emitted
from the light emitting element 342. In this case, illuminative
light can be used for communication by carrying out high-speed
modulation and driving the light emitting element 342. In addition,
modulation and driving of the infrared light emitting element 344
allow wireless communication using invisible infrared light.
[0044] As with the example shown in FIG. 3, when both lighting and
communication are required, modulation and driving of the light
emitting element 342 are carried out, thereby transmitting data. As
a result, since optical power needed for lighting can also be used
for communication, high-speed and high-quality communication can be
carried out. In addition, when lighting is unnecessary but
communication is required, communication is carried out by
modulating and driving the infrared light emitting element 335 to
emit infrared light. In this case, since infrared light is
invisible, communication can be carried out without lighting. In
addition, typically, since people are often absent when lights are
off, adverse influences on the human body such as eyes can be
decreased.
[0045] Needless to say, as with the example shown in FIG. 3, with
lighting, infrared light communication may be carried out by
modulating and driving the infrared light emitting element 344, or
by modulating and driving both the light emitting element 342 and
the infrared light emitting element 344. Note that according to the
configuration shown in FIG. 5, it is possible to transmit different
pieces of data in parallel by driving the light emitting element
342 and the infrared light emitting element 344 individually,
however, it is impossible to transmit different pieces of data via
a red, a green, and a blue illuminative light wavelength,
respectively.
[0046] FIG. 7 is a block diagram of an illuminative light
communication device, according to a second embodiment of the
present invention. Symbols in the drawing are the same as those in
FIG. 1. According to the aforementioned first embodiment,
communication without lighting is carried out by the communicating
unit 317, which is additionally provided. In the second embodiment,
an example where communication is carried out by a lighting unit
316 without a communicating unit 317 without lighting is shown.
[0047] In this exemplary structure, a switch 312 is used for
turning lights on or off while a switch 313 is used for changing
over between carrying out and not carrying out communication.
[0048] An electric power divider 315 drives the lighting unit 316
in accordance with the statuses of the respective switches 312 and
313. It carries out optical communication by modulating in
accordance with data to be transmitted while supplying electric
power sufficient for lighting to the lighting unit 316. On the
other hand, it carries out communication without lighting by
modulation-controlling in conformity with data to be transmitted so
as to make the lighting unit 316 blink a necessary number of times
for communication.
[0049] For example, when the switches 312 and 313 are turned on,
illuminative light communication is carried out through modulation
while the lighting unit 316 is illuminating. In addition, when the
switch 312 is turned off and the switch 313 is turned on,
communication is carried out by driving the lighting unit 316 in
conformity with a modulation signal from an optical modulator 311,
and making the lighting unit 316 emit for a short time in
conformity with data to be transmitted. Short time light emission
is unperceivable. Accordingly, even when light is actually emitted,
it appears to the human eye as if not illuminating, thereby
allowing carrying out communication even when not illuminating.
Note that when the switch 312 is turned on and the switch 313 is
turned off, ordinary lighting is carried out; otherwise, when both
the switches 312 and 313 are turned off, communication is not
carried out without lighting.
[0050] In this manner, since without lighting, the lighting unit
316 is controlled not to continuously illuminate, but is allowed to
illuminate for a short time in conformity with data, visible light
communication can be carried out by the lighting unit 316 while it
appears to the human eye as if not illuminating.
[0051] As described above, other than communication through short
time light emission, communication by making the lighting unit 316
emit a low intensity of light that allows communication is
possible. In this case, without lighting, communication is often
possible as long as lighting is not completely prohibited, or
illuminating with almost the same intensity as that provided by a
safety lamp.
[0052] As described above, the present invention allows provision
of an illuminative light communication device capable of carrying
out communication even without lighting, and also provision of a
lighting element preferable to be used for the illuminative light
communication device.
[0053] An illuminating facility may be available around the clock,
or otherwise, may not illuminate while unattended, while surrounded
by sunlight or while using a projector. An attempt of data
transmission using only illuminative light in such a case develops
a problem that lighting is required as data is transmitted. The
present invention allows communication even without lighting by
carrying out infrared light communication without lighting, or by
using a low light intensity for short-time communication.
[0054] In addition, in the case of using infrared light
communication, provision of a lighting element integrally made up
of an illuminative light emitting element and an infrared light
emitting element allows infrared light communication without
lighting, as described above. Furthermore, lights ranging from
visible light to infrared light can be emitted by an integrated
element, which allows decrease in device size. In other words,
rather than using an independent lighting system and an independent
infrared data communication system, a new compact system structured
by integrating lighting elements can be provided. From a different
point of view, wireless infrared light data communication has been
well-known, but it has been structured regardless of lighting. In
other words, a transmitter/receiver unit other than a lighting unit
is fixed to the ceiling. Therefore, it is often difficult to fix it
across a large area of the ceiling, and an adverse influence of
shadowing or the like may prevent utilization thereof. However, use
of the lighting elements, according to the present invention,
allows easy integration of an infrared light data communication
system and a lighting system. Since lighting units are typically
fixed to a large area of the ceiling or the like, the lighting
elements, according to the present invention, can be easily fixed
to the large area for data communication. As a result, an adverse
influence of shadowing is decreased, and reliable wireless infrared
light communication can be provided.
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