U.S. patent application number 12/461225 was filed with the patent office on 2009-12-17 for illuminative light communication system.
This patent application is currently assigned to Nakagawa Laboratories, Inc.. Invention is credited to Shinichiro Haruyama, Takaaki Ishigure, Yasuhiro Koike, Toshihiko Komine, Masao Nakagawa.
Application Number | 20090310976 12/461225 |
Document ID | / |
Family ID | 32180882 |
Filed Date | 2009-12-17 |
United States Patent
Application |
20090310976 |
Kind Code |
A1 |
Nakagawa; Masao ; et
al. |
December 17, 2009 |
Illuminative light communication system
Abstract
An light source control unit controls the flashing of a light
source and the light amount of a light source according to
information to be transmitted. Thus, light, which is modulated
according to the information to be transmitted, is emitted from the
light source. The light emitted from the light source is made to
enter an optical fiber to pass therethrough and enter a
light-scattering body which scatters and radiates the modulated
light incident from the optical fiber. The scattered light serves
as illumination light as it is. Furthermore, if the illumination
light is decoded by a decoding unit after being received by a
photoreceptor unit of a receiving set, then information carried by
the illumination light can be received.
Inventors: |
Nakagawa; Masao; (Kanagawa,
JP) ; Komine; Toshihiko; (Shizuoka, JP) ;
Haruyama; Shinichiro; (Kanagawa, JP) ; Ishigure;
Takaaki; (Kanagawa, JP) ; Koike; Yasuhiro;
(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.: |
12/461225 |
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/JP03/13539 |
Oct 23, 2003 |
|
|
|
12461225 |
|
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Current U.S.
Class: |
398/183 |
Current CPC
Class: |
G09F 9/33 20130101; H04B
10/1141 20130101; F21Y 2115/10 20160801; H04B 3/54 20130101; H01L
2924/3025 20130101; H01L 25/0753 20130101; H04B 2203/5412 20130101;
F21V 33/0052 20130101; H04B 10/116 20130101; H04B 2203/5458
20130101; H05B 47/195 20200101; H05B 47/185 20200101; H01L
2224/48091 20130101; H01L 2224/48247 20130101; F21K 9/20 20160801;
F21K 9/65 20160801; H04B 10/1149 20130101; H05B 47/19 20200101;
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: |
398/183 |
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 system for transmitting data
using illuminative light, comprising: a light source that emits
light for lighting; a light source control unit that controls
blinking or light intensity of the light source in accordance with
data to be transmitted and controls the light source to emit
modulated light; an optical fiber that transmits the modulated
light emitted from the light source; and a light scatterer that is
provided at an end of the optical fiber, scatters the modulated
light transmitted through the optical fiber, and emits the
scattered, modulated light; wherein the scattered light emitted
from the light scatterer is used for lighting and transmission of
the data.
2. The illuminative light communication system according to claim
1, wherein the optical fiber and the light scatterer are made of a
plastic material.
3. The illuminative light communication system according to claim
1, wherein the optical fiber and the light scatterer are integrated
into one.
4. The illuminative light communication system according to claim
1, wherein the light source emits an ultraviolet ray or a blue
light; and fluorescer is mixed in the light scatterer.
5. The illuminative light communication system according to claim
1, wherein a plurality of light sources is provided and emits
different color lights, respectively.
6. The illuminative light communication system according to claim
5, wherein the light source control unit controls blinking or light
intensity of at least one of the light sources.
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. 2003-323052 filed Sep. 16, 2003, the contents of which are
incorporated herein by reference in their entireties.
DISCLOSURE OF THE INVENTION
[0002] The present invention aims to provide an illuminative light
communication system that allows high-quality communication and
increase in a communication rate using a lighting device with an
optical fiber.
[0003] According to such objective, an illuminative light
communication system for transmitting data using illuminative light
includes a light source that emits light for lighting, a light
source control unit that controls blinking or light intensity of
the light source in accordance with data to be transmitted and
controls the light source to emit modulated light, an optical fiber
that transmits the modulated light emitted from the light source,
and a light scatterer that is provided at an end of the optical
fiber, scatters the modulated light transmitted through the optical
fiber, and emits the scattered, modulated light. The scattered
light emitted from the light scatterer is used for lighting and
transmission of the data.
[0004] The optical fiber and the light scatterer can be made of a
plastic material. The optical fiber and the light scatterer can be
integrated into one.
[0005] The light source that emits an ultraviolet ray or a blue
light can be used; and fluorescer can be mixed in the light
scatterer to carry out lighting and communication by the
fluorescer. Alternatively, multiple light sources that emit
different color lights, respectively, can be provided. In this
case, the light source control unit can control blinking or light
intensity of at least one of the light sources.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is an explanatory diagram of a first embodiment of
the present invention;
[0007] FIG. 2 is an explanatory diagram of a first modified example
of the first embodiment, according to the present invention;
[0008] FIG. 3 is an explanatory diagram of a second modified
example of the first embodiment, according to the present
invention;
[0009] FIG. 4 is an explanatory diagram of a second embodiment,
according to the present invention;
[0010] FIG. 5 is a schematic block diagram of a modified example of
the second embodiment, according to the present invention;
[0011] FIG. 6 is a diagram describing an application, according to
the present invention;
[0012] FIG. 7 is a diagram describing an example of a conventional
lighting element using an optical fiber; and
[0013] FIG. 8 is a diagram describing an exemplary conventional
lighting element using an optical fiber. In the drawing, 401
denotes a light source, and 402 denotes an optical fiber. As shown
in FIG. 8, in the conventional lighting element using the optical
fiber 402, light emitted from the light source 401 such as a
halogen lamp, an LED, or a laser enters an end of the optical fiber
402, which then emits to the outside from the other end. This
emitted light is used for lighting.
DETAILED DESCRIPTION OF THE INVENTION
[0014] According to this method, since light with a favorable
rectilinear progression characteristic is emitted from a point
light source or an end of the optical fiber 402, a large amount of
light is emitted to a narrow viewing angle. Therefore, when
directly looking at an end of the optical fiber 402, it is very
bright. In addition, there is a disadvantage that wide-range
lighting is impossible. To solve this problem, a diffusing plate is
provided at the output end of the optical fiber 402 to diffuse
light emitted from that end of the optical fiber 402, thereby
widely emitting light, and reducing brightness.
[0015] On the other hand, indoor wireless optical communication
technologies have been used along with advancement in high-speed
communication technologies. More specifically, the infrared LAN has
been widely used not only in offices but also homes. However, a
transmitter/receiver, which is an access point to the infrared LAN,
must be provided on the ceiling. When there is an interference
between the access point and a terminal, data communication is
typically impossible. Furthermore, it is necessary to control
electric power for preventing an adverse influence on the human
body such as eyes, and is thus impossible to carry out high-speed
and high-quality communication.
[0016] To solve such problems, an illuminative light communication
system has been considered. The present invention shows a structure
for carrying out lighting and communication using an optical
fiber.
[0017] FIG. 1 is an explanatory diagram of a first embodiment of
the present invention. In the drawing, 411 denotes a light source
controller, 412 denotes a light source, 413 denotes an optical
fiber, 414 denotes a light scatterer, 415 denotes a reflector
plate, 421 denotes a receiver, 422 denotes a light receiving unit,
and 423 denotes a demodulator. A high-speed response device such as
an LED or a laser diode is used as the light source 412, which
emits light for lighting.
[0018] The light source controller 411 controls blinking or light
intensity of the light source 412 in accordance with data to be
transmitted. As a result, modulated light is emitted from the light
source 412.
[0019] The optical fiber 413 sends light emitted by the light
source 412 from one end to the other end. A glass fiber and a
plastic optical fiber (POF) may be used as the optical fiber 413.
According to comparison of these fibers, since the POF is lighter
and can have a larger diameter than a glass fiber, optical energy
density per POF cross section is lower than that of the glass
fiber. As a result, higher power optical energy may be transmitted.
In addition, the POF can be easily connected and has more
flexibility than the glass fiber.
[0020] The light scatterer 414 is provided at an end of the optical
fiber 413, and radiates light transmitted through the optical fiber
413. A high-intensity scattering optical transmission polymer may
be used as the light scatterer 414. The high-intensity scattering
optical transmission polymer may be made of a highly scattering
optical transmission (HSOT) polymer having a micron-order of a
non-uniform structure in, for example, a photonics polymer, and may
be used as a highly effective visible light scatterer for a
lighting element. When using the POF as the optical fiber 413,
since the light scatterer 414 and the optical fiber 413 are made of
plastic, integrating them into one is possible. For example, this
integration may be carried out by individually fabricating each of
them, or alternatively, by making adjustments to additives and
fabrication conditions. The light scatterer 414 may have an
arbitrary shape. For example, it may have a hemispherical shape as
shown in FIG. 1, to the center of which an end of the optical fiber
413 is connected.
[0021] The reflector plate 415 has a mirror surface facing the
light scatterer 414, and returns scattered light from the top of
the light scatterer 414 into the light scatterer 414 so as to
increase the amount of scattered light from the bottom of the light
scatterer 414. This reflector plate 415 may be made of another
material. Alternatively, it may have a reflecting surface formed by
coating or depositing a reflector material upon a reflecting
surface. Note that this exemplary structure is assumed to have the
hemispherical light scatterer 414 as shown in FIG. 1 to illuminate
from a room ceiling. In such a case, since the flat surface of the
hemisphere faces the ceiling, and emission of scattered light from
this surface is unnecessary, the reflector plate 415 is provided on
the flat surface of the light scatterer 414 so as to increase
lighting efficiency. However, when it is unnecessary to improve the
shape of a lighting element and/or lighting efficiency, a structure
without the reflector plate 415 is possible.
[0022] The receiver 421 receives the modulated scattered light
emitted from the light scatterer 414 via the optical fiber 413 as
described above, resulting in reception of the transmitted data. To
do this operation, it is made up of a light receiving unit 422 and
a demodulator 423. The light receiving unit 422 receives modulated
scattered light emitted from the light scatterer 414 via the
optical fiber 413, converts it to an electric signal, and then
transmits the resulting signal to the demodulator 423. The
demodulator 423 demodulates the electric signal corresponding to
the intensity of the light received by the light receiving unit
422, and reconstructs the original data. This allows reception of
transmitted data.
[0023] An exemplary operation of a first embodiment according to
the aforementioned the present invention is described. The present
invention can be used as a lighting element as is when not
transmitting data. In other words, light emitted from the light
source 412 enters into and passes through the optical fiber 413,
and then enters the light scatterer 414. The light scatterer 414
scatters the incident light from the optical fiber 413, and
scatters and radiates it. Note that light emitted from the flat top
surface of the hemispheric light scatterer 414 is reflected by the
reflector plate 415, entering the light scatterer 414 again, and is
then scattered. This light scattered by the light scatterer 414
should be used as illuminative light.
[0024] In this manner, when using the light scatterer 414 as a
lighting element, the light scatterer 414 is provided at an output
end of the optical fiber 413, and light passing through the optical
fiber 413 is radiated as scattered light. Therefore, brightness per
unit area is lower than that provided through directly illuminating
from an end of the optical fiber 413. Accordingly, in direct sight,
it is not so bright. In addition, the light scatterer 414 can
illuminate a wide area.
[0025] Furthermore, in the case of integrating the light scatterer
414 and the optical fiber 413 into one, only the light scatterer
414 needs to be provided indoors, and large devices such as
conventional lighting elements are unnecessary. In addition, indoor
light sources such as conventional lighting elements are
unnecessary as long as light can be transferred via the optical
fiber 413 regardless of the position of the light source 412.
Accordingly, when used in a place where a problem such as an
electrical short circuit may develop, the light source 412 may be
used as a lighting element and may be deployed in another room and
the optical fiber 413 may be extended thereto. This allows safe
lighting without developing problems such as an electric leakage
and an electrical short circuit.
[0026] When transmitting data, the data to be transmitted is
provided to the light source controller 411. The light source
controller 411 controls blinking or light intensity of the light
source 412 in accordance with the received data to be transmitted,
thereby emitting light modulated in accordance with the data to be
transmitted from the light source 412. As with the aforementioned
case of lighting, modulated light emitted from the light source 412
enters into the optical fiber 413, and passing it through to the
light scatterer 414. The light scatterer 414 scatters the incident
modulated light from the optical fiber 413 and then emits the
resulting scattered light. Even if the light scatterer 414 has
scattered light, there is no influence on the frequency of the
modulated light as long as that frequency is lower than the optical
frequency. As a result, modulated scattered light is emitted from
the light scatterer 414.
[0027] In addition, since a high-speed response device is used as
the light source 412 as described above, the light source
controller 411 can control fast blinking and/or light intensity,
resulting in change in fast blinking and/or light intensity of
modulated scattered light emitted from the light scatterer 414.
However, high-speed change in blinking and/or high-speed light
intensity is unperceivable to the human eye, and it seems like
light illuminates at an almost constant light intensity. As a
result, scattered light emitted from the light scatterer 414 can be
used as illuminative light as is even when it has been
modulated.
[0028] When receiving data, the light receiving unit 422 of the
receiver 421 should receive the modulated scattered light emitted
from the light scatterer 414. Light received by the light receiving
unit 422 is converted to an electric signal, and the resulting
electric signal is then transmitted to the demodulator 423. Data
can then be reconstructed by the demodulator 423 demodulating that
signal.
[0029] In this way, lighting and data transmission are possible.
According to the conventional optical fiber communication, it is
difficult to move a receiver because an optical fiber must be
extended to the receiver. On the other hand, the present invention
allows data reception wherever illuminative light can be received.
In addition, since direct connection to the optical fiber is
unnecessary, the receiver is movable. For example, it is possible
to use a portable terminal together with the receiver 421. In
addition, according to the conventional infrared data communication
and wireless communication, a specific transmitter besides a
lighting element must be provided. On the other hand, the present
invention allows lighting and communication by providing the light
scatterer 414 as a lighting element, which is typically provided
indoors, and extending the optical fiber 413 instead of an electric
wire.
[0030] In addition, since scattered light is emitted by the light
scatterer 414, an expanded illuminative range can be provided,
allowing expansion in communicative range. Furthermore, a high
electric power ranging from several watts to several tens of watts
is needed for lighting. However, since that power can be used for
communication, high-speed and high-quality communication is
possible.
[0031] FIG. 2 is an explanatory diagram of a first modified example
of the first embodiment according to the present invention. In the
drawing, the same symbols are given to the same parts as those in
FIG. 1, and repetitive descriptions thereof are thus omitted. With
the aforementioned structure, since communication is possible as
long as a receiver 421 can receive illuminative light, the shape of
the light scatterer 414 may be arbitrary, and various shapes are
available. The first modified example shows a case that a
flat-plate light scatterer 414 is used as an example. Note that the
structure and operation are the same as those described above
except that the shape of the light scatterer 414 is a flat
plate.
[0032] By using such flat-plate light scatterer 414, incident light
to the light scatterer 414 from the optical fiber 413 is scattered
in the horizontal direction, and light scattered in the vertical
direction is emitted from a flat surface. By using scattered light
emitted from the flat surface as illuminative light, the light
scatterer 414 can be used as a two-dimensional illuminative light
source. This allows provision of a very thin lighting element as
thin as the light scatterer 414.
[0033] Note that when there is a surface from which emission of
scattered light is unnecessary, a reflector plate 415 shown in FIG.
1 or a reflecting surface corresponding to the reflector plate 415
may be formed on that surface. In the exemplary structure shown in
FIG. 2, the reflector plate 415 is provided upon the upper surface
of the flat-plate light scatterer 414. This reflector plate 415
returns the scattered light emitted from the top of the light
scatterer 414 into the light scatterer 414 again, allowing increase
in lighting efficiency.
[0034] In addition, since light passing through an optical fiber
413 has a rectilinear progression characteristic, sufficient
scattering by only a single-plate light scatterer 414 may be
impossible. In such cases, multiple-plate light scatterers 414 may
be overlapped. This allows increase in scattering angle, and
emission of further uniformly scattered light over a wider angle.
In addition, a reflector plate may be provided on a surface
opposite to a joint surface between the light scatterer 414 and the
optical fiber 413 so as to reflect rectilinear propagating light,
changing the propagating direction, and thereby sufficiently
scattering it. Alternatively, sufficient scattering may also be
achieved by using multiple optical fibers from which incident
lights hit the light scatterer 414 in multiple directions.
[0035] FIG. 3 is an explanatory diagram of a second modified
example of the first embodiment according to the present invention.
In the drawing, the same symbols are given to the same parts as
those in FIG. 1, and repetitive descriptions thereof are thus
omitted. 416 denotes a fluorescent material. In the second modified
example, ultraviolet rays or a blue LED or a laser diode is used as
a light source 412. In addition, a light scatterer 414 is mixed
with the fluorescent material 416.
[0036] Incident ultraviolet rays or blue light emitted from the
light source 412 via an optical fiber 413 hit the light scatterer
414. As with fluorescent lamps, the fluorescent material 416 in the
light scatterer 414 is then exited by the incident ultraviolet rays
or blue light, resulting in emission of white light. This white
light is radiated from the light scatterer 414. The light radiated
from the light scatterer 414 may be used as illuminative light for
lighting. In addition, control of the light source 412 to blink or
to emit a controlled intensity of light in accordance with data to
be transmitted allows the light source 412 to emit modulated
ultraviolet rays or blue light. As a result, modulated white light
is radiated from the light scatterer 414. Reception of that white
light by the light receiving unit 422 in the receiver 421 allows
data communication.
[0037] Note that the light scatterer 414 in this case is not
limited to having a hemispheric shape as shown in FIG. 3, and
various shapes such as a flat plate as shown in FIG. 2 are
available.
[0038] FIG. 4 is an explanatory diagram of a second embodiment of
the present invention. In the drawing, the same symbols are given
to the same parts as those in FIG. 1, and repetitive descriptions
thereof are thus omitted. In the second embodiment, multiple
optical fibers 413 are connected to a single light scatterer 414,
and lights with different wavelengths are sent to the optical
fibers 413, respectively. In the exemplary structure shown in FIG.
4, a red, a green, and a blue light source are used as a light
source 412, and color lights emitted from the light sources 412
enter into three optical fibers 413, respectively.
[0039] The red, the green, and the blue light entered into the
respective optical fibers 413 passing therethrough then hit the
light scatterer 414. Respective incident color lights that hit the
light scatterer 414 scatter and mix with each other, resulting in
radiation of white light. Accordingly, when using light emitted
from the light scatterer 414 as illuminative light, it can be used
as a white light source. Needless to say, besides using it as a
white light source, illuminative light with an arbitrary color can
be provided by making adjustments to intensity respective color
lights.
[0040] In the case of data communication, all of or some of those
multiple light sources 412 may be controlled to be driven at the
same time. In the exemplary structure shown in FIG. 4, only an LED
or a laser diode which emits red color light is controlled to be
driven and a green and a blue LED or laser diodes are not
controlled to be driven. Consequently, only red light is modulated,
but other color lights are not. For example, such a structure is
effective when the light receiving unit 422 in the receiver 421 has
the highest sensitivity to red light or infrared rays.
[0041] When some of color lights are modulated as described above,
it is desirable that the receiver 421 receives and demodulates
those modulated optical components. For example, in the case where
red light is modulated by the exemplary structure shown in FIG. 4,
data can be reliably received by selectively receiving red light
using various well-known methods and then demodulating it by the
demodulator 423; wherein those various well-known methods may be
one that provides a red light passing filter, one that uses the
light receiving unit 422 having high optical sensitivity to red
light, or one that divides red light using a prism.
[0042] Note that light passing through the multiple optical fibers
413 can be arbitrary and is not limited to the aforementioned red,
green or blue light, and that light intensity may be changed as
desired. For example, the same color light may be used to increase
light intensity. Alternatively, when using the red, the green, and
the blue light source 412, as described above, three-color light s
may enter into a single optical fiber 413. In addition, color of
light to be modulated in transmitting data is not limited to red,
and other multiple color lights should be modulated.
[0043] In the structure shown in FIG. 4, the light sources 412 may
be controlled to be driven individually in accordance with
different pieces of data, respectively, allowing transmission of
multiple pieces of data. In other words, it is possible to transmit
first data using red light, second data using green light, and
third data using blue light. By selecting a color of light to be
received by the receiver 421, transmitted data can be selectively
received based on the selected color.
[0044] In addition, besides multiple optical fibers 413 through
which illuminative light passes, another optical fiber for data
transmission may be provided to transmit data by controlling a
light source corresponding to that optical fiber. In this case, use
of a white light source allows transmission of data without
changing illuminative light color. Alternatively, use of infrared
light also allows data transmission.
[0045] FIG. 5 is a schematic block diagram of a modified example of
the second embodiment according to the present invention. As shown
in FIG. 5, for example, when modulating only lights with specific
colors, a structure of providing a light scatterer 414 with
modulated light from only a light source 412, which is controlled
to be driven by a light source controller 411, via the optical
fibers 413 and directly providing a light scatterer 414 with lights
emitted by light sources 412, which emit lights with other colors,
is possible. In this case, since incident color lights are mixed
and synthesized at the light scatterer 414, the resulting
synthesized lights may be used as illuminative light. Moreover,
since a specific color light is modulated, and that optical
component thereof is received by a light receiving unit 422 in a
receiver 421 and then demodulated by a demodulator 423, data can be
reconstructed. FIG. 5 shows an example of modulating red light, but
the present invention is not limited to this. Alternatively, blue
or green light may be modulated, or two of the three colors may be
modulated.
[0046] FIG. 6 is a diagram describing an exemplary structure of an
application, according to the present invention. In this exemplary
structure, data is broadcast to multiple rooms. As described above,
according to the present invention, that structure may be used as a
lighting element. Therefore, light scatterers 414 are provided on
the room ceilings. In the case of illuminative light communication,
communication quality decreases due to shadows. When providing the
light scatterers 414 on the ceilings as described above, shadows of
someone or something are difficult to generate, which allows
avoidance of such a shadowing problem.
[0047] Meanwhile, multiple light scatterers 414 provided in a room
A are exemplified. By providing multiple light scatterers 414, it
is possible to further decrease adverse influences by shadows. When
providing multiple light scatterers 414, modulated light may be
transmitted to the multiple light scatterers 414 from the same
light source via optical fibers 413. Therefore, it is unnecessary
to provide the light source controller 411 and the light source for
each lighting element, thereby considerably reducing cost for
installation of transmitters. Needless to say, it is possible to
provide a structure of transmitting different pieces of data from
the multiple light scatterers 414. In this case, data can be
selectively received by selecting illuminative light received by a
receiver 421.
[0048] Similarly, the light scatterer 414 is also provided in a
room B. In this case, modulated light may be transmitted to the
room B from the same light source in the room A. As a result, the
same data can be broadcast to different rooms. In this case, the
light source controller 411 and the light source 412 can be shared
by different rooms.
[0049] Note that in the aforementioned first and the second
embodiment, unidirectional data communication has been described.
However, since the optical fibers 413 allows light to pass through
bi-directionally, bi-directional data communication is naturally
possible. In other words, light emitted from a light source
existing outside of the light scatterers 414 is output from an end
of the light source 412 via the light scatterers 414 and the
optical fibers 413. This structure is used to control a light
source existing outside of the light scatterers 414 to be driven to
emit modulated light. This modulated light is output from an end of
the optical fibers 413 on the light source 412 side. A light
separating means such as a half mirror is provided between the
light source 412 and the optical fibers 431, light emitted from the
end of the optical fibers 413 on the light source 412 side is
separated and received, and is then demodulated, resulting in
reception of transmitted data. This allows bi-directional data
communication. Note that the intensity of incident light to the
optical fibers 413 via the light scatterers 414 becomes extremely
weak due to scattering by the light scatterers 414. However,
improved optical sensitivity and signal identifying technology
allows reliable data communication.
[0050] According to the present invention as described above,
provision of an optical fiber and a light scatterer allows lighting
and illuminative light communication. Moreover, it is unnecessary
to provide a lighting element and a communication device on a
ceiling separately as with prior arts. In addition, illuminative
light communication allows high-electric power communication.
Therefore, high-speed and high-quality communication is possible.
In addition, since a lighting element has large electric power and
is typically deployed at a site that is difficult to develop
shadows, a shadowing problem with infrared LAN, or a problematic
phenomenon that communication is interrupted due to an interference
may considerably decrease. Furthermore, light emitted from a light
source is output from a light scatterer via an optical fiber. In
this case, only light is used without an electric circuit, allowing
simplification of a system and prevention of development of
problems such as an electrical leakage and an electrical short
circuit.
* * * * *