U.S. patent application number 12/111866 was filed with the patent office on 2008-08-28 for electric field sensor device, transceiver, positional information obtaining system, and information input system.
This patent application is currently assigned to Nippon Telegraph and Telephone Corporation. Invention is credited to Hakaru Kyuragi, Tadashi Minotani, Katsuyuki Ochiai, Aiichirou Sasaki, Nobutarou Shibata, Mitsuru Shinagawa.
Application Number | 20080205904 12/111866 |
Document ID | / |
Family ID | 33556162 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080205904 |
Kind Code |
A1 |
Shinagawa; Mitsuru ; et
al. |
August 28, 2008 |
Electric Field Sensor Device, Transceiver, Positional Information
Obtaining System, and Information Input System
Abstract
When a human hand (100) holds a transceiver (3a), the hand holds
a bottom of an external wall surface and a side of the external
wall surface of an insulating case (33). Therefore, a transmitting
and receiving electrode (105) and an insulating film (107) cover
not only the bottom of the external wall surface but also the side
of the external wall surface of the insulating case (33). A first
ground electrode (131), a second ground electrode (161), and a
third ground electrode (163) are attached to upper portions of the
internal wall surface of the insulating case (33) apart from the
transmitting and receiving electrode (105). An insulating foam
member (7a) is interposed between the insulating case (33) and a
transceiver main body (30), and an insulating foam member (7b) is
interposed between the transceiver main body (30) and a battery
(6).
Inventors: |
Shinagawa; Mitsuru; (Tokyo,
JP) ; Ochiai; Katsuyuki; (Chiyoda-ku, JP) ;
Minotani; Tadashi; (Tokyo, JP) ; Sasaki;
Aiichirou; (Tokyo, JP) ; Shibata; Nobutarou;
(Tokyo, JP) ; Kyuragi; Hakaru; (Tokyo,
JP) |
Correspondence
Address: |
JOHN S. PRATT, ESQ;KILPATRICK STOCKTON, LLP
1100 PEACHTREE STREET
ATLANTA
GA
30309
US
|
Assignee: |
Nippon Telegraph and Telephone
Corporation
Tokyo
JP
|
Family ID: |
33556162 |
Appl. No.: |
12/111866 |
Filed: |
April 29, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10524485 |
Feb 14, 2005 |
|
|
|
PCT/JP04/09159 |
Jun 29, 2004 |
|
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|
12111866 |
|
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Current U.S.
Class: |
398/186 |
Current CPC
Class: |
G06F 3/041 20130101;
G06F 1/163 20130101; H04B 13/005 20130101 |
Class at
Publication: |
398/186 |
International
Class: |
H04B 10/04 20060101
H04B010/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2003 |
JP |
2003188553 |
Jul 23, 2003 |
JP |
2003278171 |
Aug 6, 2003 |
JP |
2003287753 |
Claims
1. An information input system comprising: electric field inducing
means that is contacted or operated by an electric field
transmission medium, and induces an electric field in said electric
field transmission medium according to a physical quantity based on
the contact or operation; a transceiver that receives the electric
field induced in said electric field transmission medium, applies
the electric field to a polarization modulator or an optical
intensity modulator, polarization-modulates or optical
intensity-modulates laser light according to the electric field,
converts the polarization-modulated or optical intensity-modulated
laser light into an electric signal, extracts an electric signal
having a frequency component concerning a physical quantity based
on said contact or operation from the converted electric signals,
and outputs the electric signal concerning the physical quantity
based on said contact or operation; and information processing
means for inputting therein the electric signal concerning the
physical quantity based on said contact or operation from said
transceiver, and obtaining information corresponding to the
physical quantity based on said contact or operation by said
electric field transmission medium.
2. An electric field sensor device that modulates optical intensity
of laser light based on an electric field to be detected, thereby
detecting said electric field, said electric field sensor device
having an electric field sensor unit and a light receiving circuit,
wherein said electric field sensor unit includes: laser light
emitting means; branching means for branching a laser light emitted
from said laser light emitting means into a first laser light and a
second laser light that are different from each other; and optical
intensity modulating means with which said electric field to be
detected is coupled, that modulates the optical intensity of said
first laser light based on said coupled electric field, and said
light receiving circuit includes: first light/voltage converting
means for converting the optical intensity of said first laser
light modulated by said optical intensity modulating means into a
voltage signal; second light/voltage converting means for
converting the optical intensity of said second laser light
branched by said branching means into a voltage signal; and
differential amplifying means for differentially amplifying the
voltage signal obtained by conversion by said first light/voltage
converting means and the voltage signal obtained by conversion by
said second light/voltage converting means.
3. The electric field sensor device according to claim 2, wherein
said electric field sensor unit further includes an optical
variable attenuator that attenuates the optical intensity of said
second laser light obtained by branching by said branching means,
and said second photoelectrical converting means inputs said second
laser light attenuated by said optical variable attenuator.
4. The electric field sensor device according to claim 2, wherein
said electric field sensor unit further includes a first optical
variable attenuator that attenuates the optical intensity of said
first laser light obtained by branching by said branching means at
a predetermined rate, and a second optical variable attenuator that
attenuates the optical intensity of said second laser light
obtained by branching by said branching means at a rate higher than
an attenuation rate of said first optical variable attenuator, said
optical intensity modulating means inputs therein said first laser
light attenuated by said first optical variable attenuator, and
said second photoelectrical converting means inputs therein said
second laser light attenuated by said second optical variable
attenuator.
5. The electric field sensor device according to claim 2, wherein
said first light/voltage converting means includes: first
light/current converting means for converting the optical intensity
of said first laser light modulated by said optical intensity
modulating means into a current signal; a first voltage source that
applies an inverse bias voltage to said first light/current
converting means; and a first load resistor that converts said
current signal obtained by conversion by said first light/current
converting means into a voltage signal, and said second
light/voltage converting means includes: second light/current
converting means for converting the intensity of said second laser
light obtained by branching by said branching means into a current
signal; a second voltage source that applies an inverse bias
voltage to said second light/current converting means; and a second
load resistor that converts said current signal obtained by
conversion by said second light/current converting means into a
voltage signal.
6. The electric field sensor device according to claim 5, wherein
at least one of said first load resistor and said second load
resistor is a variable resistor.
7. The electric field sensor device according to claim 5, wherein
at least one of said first voltage source and said second voltage
source is a variable voltage source.
8. The electric field sensor device according to claim 2, wherein
said light receiving circuit further includes amplifying means for
amplifying at least one of the voltage signal obtained by
conversion by said first light/voltage converting means and the
voltage signal obtained by conversion by said second light/voltage
converting means.
9. A transceiver that receives information based on an electric
field induced in an electric field transmission medium, thereby
receiving the information via said electric field transmission
medium, said transceiver comprising: said electric field sensor
device according to claim 2; a signal processing circuit that at
least removes a noise from a voltage signal output from said
electric field sensor device; noise detecting means for detecting
quantity of a noise component of the voltage signal output from
said signal processing circuit; and a control signal generator that
generates a control signal to variably control a variable value of
said electric field sensor unit or said light receiving circuit
based on the detection data output from said noise detecting means.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 10/524,485 filed Feb. 14, 2005, entitled "Electric Field Sensor
Device, Transceiver, Positional Information Obtaining System, and
Information Input System," which is a 371 of PCT/JP2004/009159,
filed Jun. 29, 2004 the entirety of which is incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a transceiver that is used
to carry out data communications between wearable computers, for
example. More particularly, the present invention relates to a
transceiver that can receive information via an electric field
transmission medium by receiving information based on an electric
field induced in the electric field transmission medium.
[0003] The present invention further relates particularly to a
transceiver including a transceiver main body that can transmit
information via an electric field transmission medium by inducing
an electric field based on the information to be transmitted from a
transmitting electrode to the electric field transmission medium, a
battery that drives the transceiver main body, and an insulating
case that incorporates the transceiver main body.
[0004] The present invention further relates to an electric field
sensor device that detects an electric field by modulating the
optical intensity of laser light based on an electric field to be
detected, and a transceiver that has the electric field sensor
device.
[0005] The present invention further relates to positional
information obtaining system including electric field inducing
means for inducing an electric field in an electric field
transmission medium corresponding to a position at which the
electric field inducing means is brought into contact with the
electric field transmission medium, and a transceiver that obtains
information at the above position by receiving the electric field
induced in the electric field transmission medium and converting
the electric field into an electric signal.
[0006] The present invention further relates to an information
input system that obtains information based on positional
information and the like from the positional information obtaining
system.
BACKGROUND ART
[0007] In recent years, a computer with a new concept of being
wearable like clothes and able to be operated and used in this
state is drawing attention. This computer is called a wearable
computer, and is realized based on small and high-performance
personal digital assistants.
[0008] Progressive researches are also conducted on a technique of
carrying out data communications between plural wearable computers
via parts of a human body such as arms, shoulders, and bodies. This
technique is already proposed in patent literatures and the like
(for example, see Japanese Patent Application Laid-Open No.
2001-352298 (pages 4 to 5, FIGS. 1 to 5)). FIG. 1 shows an image of
carrying out communications between plural wearable computers via a
human body. As shown in FIG. 1, a wearable computer 1 and a
transceiver 3' that is brought into contact with the wearable
computer 1 constitute one set. A set of a wearable computer 1 and a
transceiver 3' can carry out data communications with other set of
a wearable computer 1 and a transceiver 3', via a human body. The
wearable computer 1 can also carry out data communications with
other set of a personal computer (PC) 5 which is other than the
wearable computer 1 mounted on the human body and a transceiver 3'a
installed on a wall or the like, or a set of the PC 5 and a
transceiver 3'b installed on a floor or the like. In this case, the
PC 5 is not brought into contact with the transceivers 3'a and 3'b
unlike the wearable computer 1 and the transceiver 3', but is
connected via a cable 4, to the transceivers 3'a and 3'b.
[0009] Regarding the data communications via a human body, a signal
detection technique according to an electro-optic method using a
laser light and an electro-optic crystal is utilized. With this
arrangement, an electric field based on information (data) to be
transmitted is induced in a human body (i.e., electric field
transmission medium), and information based on the electric field
induced in the human body is received, thereby achieving
transmission and reception of the information. The technique of
data communications via the human body is explained in detail with
reference to FIG. 2.
[0010] FIG. 2 is an overall configuration diagram of a transceiver
main body 30' that is used to carry out data communications via a
human body 100. As shown in FIG. 2, the transceiver main body 30'
is used in a state of being in contact with the human body 100 via
a transmitting and receiving electrode 105' and an insulating film
107'. The transceiver main body 30' receives data supplied from the
wearable computer 1 via an I/O (input/output) circuit 101, and
transmits the data to a transmitter 103. The transmitter 103
induces an electric field in the human body 100 as an electric
field transmission medium from the transmitting and receiving
electrode 105' via the insulating film 107'. The transmitter 103
transmits this electric field to other transceiver 3' mounted on
other part of the human body 100 via the human body 100.
[0011] In the transceiver main body 30', the transmitting and
receiving electrode 105' receives an electric field induced in the
human body 100 and transmitted from a separate transceiver 3'
mounted on other part of the human body 100 via the insulating film
107'. An electric field sensor unit 110' that constitutes an
electric field sensor device 115' applies the received electric
field to the above electro-optic crystal, thereby generating a
polarization change and an intensity change in the laser light. A
light receiving circuit 152' that constitutes the electric field
sensor device 115' receives the polarization-changed and
intensity-changed laser light, and converts the laser light into an
electric signal, and processes this electric signal such as
amplifies this electric signal. A signal processing circuit 116
that constitutes a receiver circuit 113 removes a frequency
component other than a frequency component concerning reception
information as the electric field to be detected out of electric
signals of various frequencies (i.e., extracts only the frequency
component concerning the reception information) with a band pass
filter that constitutes the signal processing circuit 116, thereby
removing noise from the electric signal. A waveform shaping circuit
117 that constitutes the receiver circuit 113 shapes the waveform
(i.e., carries out a signal processing) of the electric signal that
passes the signal processing circuit 116, and supplies the
waveform-shaped electric signal to the wearable computer 1 via the
input/output circuit 101.
[0012] As shown in FIG. 3, the electrode can be divided into two
for transmission and for reception, respectively. In other words,
the transmitter 103 induces an electric field in the human body 100
as an electric field transmission medium from a transmitting
electrode 105'a via an insulating film 107'a. On the other hand, a
receiving electrode 105'b receives an electric field induced in the
human body 100 and transmitted from a separate transceiver 3'
mounted on other part of the human body 100 via an insulating film
107'b. Other configurations and their operation are similar to
those shown in FIG. 2.
[0013] For example, as shown in FIG. 1, the wearable computer 1
mounted on the right arm makes the transceiver 3' induce an
electric signal concerning transmission data as an electric field
in the human body 100 as an electric field transmission medium, and
transmit the electric field to other parts of the human body 100 as
shown by a wavy line. On the other hand, the wearable computer 1
mounted on the left arm can make the transceiver 3' receive the
electric field transmitted from the human body 100, return the
electric field to the electric signal, and receive reception
data.
[0014] The computer such as the wearable computer 1 and a personal
digital assistant such as a portable telephone need to be compact
considering convenience of mounting on the human body 100 and
carrying as shown in FIG. 1.
[0015] However, along miniaturization of the computer and the
personal digital assistant, input of information to the computer
and the personal digital assistant become difficult.
[0016] On the other hand, the electric field sensor unit 110' in
the transceiver main body 30' includes ones which convert the
polarization change of laser light into the intensity change like a
polarization modulator, and ones which directly convert the
intensity change of the laser light like optical intensity
modulators such as an electroabsorption (EA) optical intensity
modulator and a Mach-Zehnder optical intensity modulator.
[0017] An electric field sensor unit 110'a and a light receiving
circuit 152'a that use a polarization modulator 123 is explained
with reference to FIG. 4 and FIG. 5, and then, an electric field
sensor unit 110'b and a light receiving circuit 152'b that use an
optical intensity modulator 124 is explained with reference to FIG.
6 to FIG. 8.
[0018] First, as shown in FIG. 4, the electric field sensor unit
110'a using the polarization modulator 123 includes a current
source 119, a laser diode 121, a lens 133, the polarization
modulator 123 such as an electro-optic element (electro-optic
crystal), a first and a second wave plates 135 and 137, a
polarizing beam splitter 139', and a first and a second lenses 141a
and 141b.
[0019] The light receiving circuit 152'a includes a first
photodiode 143a, a first load resistor 145a, a first constant
voltage source 147a, a second photodiode 143b, a second load
resistor 145b, a second constant voltage source 147b, and a
differential amplifier 112.
[0020] Of the above, the polarization modulator 123 has sensitivity
in only the electric field that is coupled in a direction
perpendicular to a proceeding direction of laser light that is
emitted from the laser diode 121. The intensity of the electric
field changes optical characteristic, that is, a birefringence
index, of the polarization modulator 123. The change of the
birefringence index of the polarization modulator 123 changes the
polarization of the laser light. A first electrode 125 and a second
electrode 127 are provided on both side surfaces of the
polarization modulator 123, that are opposite in a vertical
direction in the drawing. The first electrode 125 and the second
electrode 127 face each other perpendicular to the proceeding
direction of the laser light from the laser diode 121 in the
polarization modulator 123, and can couple the electric field with
the laser light at a right angle.
[0021] The electric field sensor unit 110'a is connected to the
receiving electrode 105'b via the first electrode 125. The second
electrode 127 that is opposite to the first electrode 125 is
connected to a ground electrode 131, and functions as a ground
electrode to the first electrode 125. The receiving electrode 105'b
detects an electric field that is transmitted after being induced
in the human body 100, transmits this electric field to the first
electrode 125, and can couple the electric field with the
polarization modulator 123 via the first electrode 125.
[0022] With this arrangement, the laser light output from the laser
diode 121 according to the current control from the current source
119 is made parallel light via the lens 133. The first wave plate
135 adjusts the polarization state of the parallel laser light, and
inputs the laser light to the polarization modulator 123. The laser
light that is incident to the polarization modulator 123 is
propagated between the first and the second electrodes 125 and 127
within the polarization modulator 123. During the propagation of
the laser light, the receiving electrode 105'b detects the electric
field that is transmitted after being induced in the human body
100, and couples this electric field with the polarization
modulator 123 via the first electrode 125. Then, the electric field
is formed from the first electrode 125 toward the second electrode
127 connected to the ground electrode 131. Since the electric field
is perpendicular to the proceeding direction of the laser light
that is incident from the laser diode 121 to the polarization
modulator 123, the birefringence index as the optical
characteristic of the polarization modulator 123 changes, and the
polarization of the laser light changes accordingly.
[0023] The second wave plate 137 adjusts the polarization state of
the laser light of which polarization is changed by the electric
field from the first electrode 125 in the polarization modulator
123, and inputs the laser light to the polarizing beam splitter
139'. The polarizing beam splitter 139' separates the laser light
input from the second wave plate 137, into a P wave and an S wave,
and converts the laser light into optical intensity change. The
first and the second lenses 141a and 141b condense respectively the
laser light that is separated into the P wave component and the S
wave component by the polarizing beam splitter 139'. The first and
the second photodiodes 143a and 143b that constitute photoelectric
converting means receive the laser light, convert the P wave light
signal and the S wave light signal into electric signals
respectively, and output the electric signals. The first load
resistor 145a, the first constant voltage source 147a, the second
load resistor 145b, and the second constant voltage source 147b
convert the current signals output from the first and the second
photodiodes 143a and 143b, into voltage signals. The differential
amplifier 112 can extract a voltage signal (intensity modulation
signal) concerning reception information by differential. The
extracted voltage signal is supplied to the signal processing
circuit 116 shown in FIG. 2 and FIG. 3.
[0024] As shown in FIG. 5, the phase of a voltage signal Sa
according to the first photodiode 143a and the phase of a voltage
signal Sb according to the second photodiode 143b are deviated by
180 degrees. Therefore, the differential amplifier 112 amplifies
the signal component of the opposite phase, and subtracts and
removes noise of the in-phase laser light.
[0025] The signal processing circuit 116 shown in FIG. 2 and FIG. 3
removes noise from the signal. The waveform shaping circuit 117
shapes the waveform of the signal, and supplies the signal to the
wearable computer 1 via the input/output circuit 101.
[0026] The electric field sensor unit 110'b and the light receiving
circuit 152'b that use the optical intensity modulator 124 is
explained with reference to FIG. 6 to FIG. 8. Constituent parts
identical with those of the electric field sensor unit 110'a and
the light receiving circuit 152'a that use the polarization
modulator 123 are assigned with the same reference numerals.
[0027] As shown in FIG. 6, the electric field sensor unit 110'b
that uses the optical intensity modulator 124 includes the current
source 119, the laser diode 121, the lens 133, the optical
intensity modulator 124 such as an electroabsorption (EA) optical
intensity modulator and a Mach-Zehnder optical intensity modulator,
and the lens 141.
[0028] The light receiving circuit 152'b includes the photodiode
143, the load resistor 145, the constant voltage source 147, and a
(single) amplifier 118.
[0029] The optical intensity modulator 124 is configured to change
the optical intensity of the light that passes due to the intensity
of the coupled electric field. The first electrode 125 and the
second electrode 127 are provided on both side surfaces of the
optical intensity modulator 124, that are opposite in a vertical
direction in the drawing. The first electrode 125 and the second
electrode 127 face each other perpendicular to the proceeding
direction of the laser light from the laser diode 121 in the
optical intensity modulator 124, and can couple the electric field
with the laser light at a right angle.
[0030] The electric field sensor unit 110'b is connected to the
receiving electrode 105'b via the first electrode 125. The second
electrode 127 that is opposite to the first electrode 125 is
connected to the ground electrode 131, and functions as a ground
electrode to the first electrode 125. The receiving electrode 105'b
detects an electric field that is transmitted after being induced
in the human body 100, transmits this electric field to the first
electrode 125, and can couple the electric field with the optical
intensity modulator 124 via the first electrode 125.
[0031] An electroabsorption (EA) optical intensity modulator 124a
as one example of the optical intensity modulator 124 is briefly
explained with reference to FIG. 7.
[0032] As shown in FIG. 7, when laser light having constant optical
intensity is input, the electroabsorption optical intensity
modulator 124a varies the optical intensity according to the
detection signal concerning the electric field with the constant
optical intensity as the maximum. In other words, the intensity of
the input laser light is attenuated based on the detection signal
concerning the electric field.
[0033] A Mach-Zehnder optical intensity modulator 124b as one
example of the optical intensity modulator 124 is briefly explained
with reference to FIG. 8.
[0034] As shown in FIG. 8, the Mach-Zehnder optical intensity
modulator 124b has two waveguides 203a and 203b having light
refraction indexes different from that of a substrate 201 formed on
the substrate 201, thereby confining laser light input via a lens
205 within the waveguides 203a and 203b and branching the laser
light. The first electrode 125 and the second electrode 127 apply
an electric field to one of the branched laser lights and couple
the electric field with the laser light. Thereafter, the
Mach-Zehnder optical intensity modulator 124b emits the laser light
via the lens 207. When the electric field is applied to one of the
laser lights, the phase of this laser light can be slightly delayed
or advanced from that of the laser light which is not applied with
the electric field.
[0035] Referring back to FIG. 6, the laser light output from the
laser diode 121 based on the current control by the current source
119 is made parallel light via the lens 133. The parallel laser
light is incident to the optical intensity modulator 124. The laser
light that is incident to the optical intensity modulator 124 is
propagated between the first and the second electrodes 125 and 127
within the optical intensity modulator 124. During the propagation
of the laser light, the receiving electrode 105'b detects the
electric field that is transmitted after being induced in the human
body 100 as explained above, and couples this electric field with
the optical intensity modulator 124 via the first electrode 125.
Then, the electric field is formed from the first electrode 125
toward the second electrode 127 connected to the ground electrode
131. Based on this coupling of the electric field, laser light of
changed optical intensity is emitted. The photodiode 143 of the
light receiving circuit 152'b receives the laser light via the lens
141. As a result, the photodiode 143 converts the laser light into
a current signal according to the optical intensity of the laser
light. The load resistor 145 and the constant voltage source 147
convert the current signal output from the photodiode 143 into a
voltage signal, and output this voltage signal. The output voltage
signal is amplified by the amplifier 118, and is supplied to the
signal processing circuit 116 shown in FIG. 2 and FIG. 3.
[0036] The signal processing circuit 116 shown in FIG. 2 and FIG. 3
remove noise. The waveform shaping circuit 117 shapes the waveform,
and supplies the signal to the wearable computer 1 via the
input/output circuit 101.
[0037] However, the optical intensity modulator 124 shown in FIG. 6
cannot extract the intensity modulation signal by differential as
shown in FIG. 5, unlike the polarization modulator 123 shown in
FIG. 4 that converts the polarization change of the laser light
into the intensity change. Therefore, the optical intensity
modulator 124 cannot carry out a differential detection. When the
photodiode 143 directly receives the output from the optical
intensity modulator 124 without carrying out a differential
detection, noise of the laser light cannot be removed, which
results in poor S/N ratio of the reception signal and degradation
of communication quality.
[0038] A human hand (human body 100) may hold a set of the
transceiver 3' and the wearable computer 1, as shown in FIG. 9. The
transceiver 3' shown in FIG. 9 has such a configuration that the
transceiver main body 30' is attached to the bottom of the internal
wall surface of the insulating case 33 configured by an insulator,
and a battery 6 that drives the transceiver main body 30' is
attached on the upper surface of the transceiver main body 30'.
Further, the transmitting and receiving electrode 105' is attached
to the bottom of the external wall surface of the insulating case
33, and this transmitting and receiving electrode 105' is covered
with the insulating film 107'. Parts other than the operation/input
surface of the wearable computer 1 are covered with an insulating
case 11.
[0039] However, when the hand holds the transceiver 3' as shown in
FIG. 9, even when an electric field E1 for transmission is induced
in the human hand (human body 100) from the transmitting and
receiving electrode 105', electric fields E2' and E3' thereof
return from the hand to the transceiver 3' via the side surface of
the insulating case 33. Therefore, the transceiver 3' does not
carry out normal transmission operation.
DISCLOSURE OF THE INVENTION
[0040] The present invention has been achieved in the light of the
above situation, and it is an object of the present invention to
provide a technique of normally carrying out transmission and
reception operation of a transceiver even if a human body as an
electric field transmission medium contacts a wide surface out of
an external wall surface of the transceiver, wherein the
transceiver includes a transceiver main body that can transmit and
receive information via the electric field transmission medium, a
battery that drives this transceiver, and an insulating case that
covers the transceiver main body.
[0041] Further, the present invention has been made in the light of
the above situation, and has an object of suppressing degradation
of communication quality of an electric field sensor device using
an optical intensity modulator to detect an electric field and a
transceiver having this electric field sensor device.
[0042] Further, the present invention has been made in the light of
the above situation, and has an object of providing a technique of
easily inputting information to a computer and a personal digital
assistant each of which is used in a set with a transceiver that
can transmit and receive information via an electric field
transmission medium.
[0043] In order to achieve the above objects, a first aspect of the
present invention provides a transceiver including: a transmitting
and receiving electrode that induces an electric field in an
electric field transmission medium, and receives the electric field
induced in said electric field transmission medium; a transceiver
main body that generates said electric field based on information
to be transmitted in said transmitting and receiving electrode, and
converts said electric field generated in said transmitting and
receiving electrode into reception information, thereby
transmitting and receiving information via said electric field
transmission medium; a first structure that is interposed between
said transmitting and receiving electrode and said electric field
transmission medium; a second structure that is interposed between
said transceiver main body and said electric field transmission
medium; a battery that drives said transceiver main body; and a
third structure that is interposed between said transceiver main
body and said battery, wherein each of said first, said second, and
said third structures is composed of at least one of metal, a
semiconductor, and an insulator, and is equivalent as a parallel
circuit of a resistor and a capacitor.
[0044] A second aspect of the present invention provides the
transceiver according to the first aspect of the invention, wherein
the impedance of said second structure and the impedance of said
third structure are larger than the impedance of said first
structure.
[0045] A third aspect of the present invention provides the
transceiver according to the second aspect of the invention,
wherein said first structure is an insulating film that covers said
transmitting and receiving electrode against said electric field
transmission medium.
[0046] A fourth aspect of the present invention provides the
transceiver according to the second aspect of the invention,
wherein said second structure and said third structure are
insulating members.
[0047] In order to achieve the above objects, a fifth aspect of the
present invention provides a transceiver including: a transceiver
main body that induces an electric field based on information to be
transmitted in an electric field transmission medium from a
transmitting electrode, thereby transmitting the information via
said electric field transmission medium; a battery that drives said
transceiver main body; and an insulating case that incorporates
said transceiver main body, wherein said transmitting electrode is
provided on the whole surface of a portion of an external wall
surface of said insulating case, said electric field transmission
medium closely approaching the portion, and is covered with an
insulating film so as not to be in direct contact with said
electric field transmission medium.
[0048] A sixth aspect of the present invention provides the
transceiver according to the fifth aspect of the invention, further
including an insulating member between said battery and said
transceiver main body.
[0049] A seventh aspect of the present invention provides the
transceiver according to the sixth aspect of the invention, wherein
the insulating member is a foam member containing air.
[0050] An eighth aspect of the present invention provides the
transceiver according to the sixth aspect of the invention, wherein
said insulating member is a plurality of wooden pillars.
[0051] A ninth aspect of the present invention provides the
transceiver according to the sixth aspect of the invention, wherein
said insulating member is a cushion member having predetermined gas
confined therein.
[0052] A tenth aspect of the present invention provides the
transceiver according to the fifth aspect of the invention, further
including a ground electrode that defines a reference voltage which
is necessary to drive said transceiver main body, and that is
attached to an internal wall surface of said insulating case.
[0053] An eleventh aspect of the present invention provides the
transceiver according to the fifth aspect of the invention, further
including a ground electrode that defines a reference voltage which
is necessary to drive said transceiver main body, and that is
attached to an external device at the outside of said insulating
case.
[0054] In order to achieve the above objects, a twelfth aspect of
the present invention provides a transceiver including: a
transceiver main body that induces an electric field based on
information to be transmitted in an electric field transmission
medium from a transmitting electrode, and receives information
based on the electric field induced in said electric field
transmission medium with a receiving electrode, thereby
transmitting and receiving the information via said electric field
transmission medium; a battery that drives said transceiver main
body; and an insulating case that incorporates said transceiver
main body, wherein said transmitting electrode is provided on the
whole surface of a portion of an external wall surface of said
insulating case, said electric field transmission medium closely
approaching the portion, and is covered with a first insulating
film so as not to be in direct contact with said electric field
transmission medium, and said receiving electrode is provided on an
external wall surface of said first insulating film, and is covered
with a second insulating film so as not to be in direct contact
with said electric field transmission medium.
[0055] In order to achieve the above objects, a thirteenth aspect
of the present invention provides a transceiver including: a
transceiver main body that induces an electric field based on
information to be transmitted in an electric field transmission
medium from a transmitting electrode, and receives information
based on the electric field induced in said electric field
transmission medium with a receiving electrode, thereby
transmitting and receiving the information via said electric field
transmission medium; a battery that drives said transceiver main
body; and an insulating case that incorporates said transceiver
main body, wherein said receiving electrode is provided on the
whole surface of a portion of an external wall surface of said
insulating case, said electric field transmission medium closely
approaching the portion, and is covered with a first insulating
film so as not to be in direct contact with said electric field
transmission medium, and said transmitting electrode is provided on
an external wall surface of said first insulating film, and is
covered with a second insulating film so as not to be in direct
contact with said electric field transmission medium.
[0056] In order to achieve the above objects, a fourteenth aspect
of the present invention provides a transceiver that receives
information based on an electric field induced in an electric field
transmission medium, thereby receiving information via said
electric field transmission medium, said transceiver including:
memory means for storing information based on two electric signals
and positional information determined according to the electric
signal information, by relating these pieces of information to each
other; electric field detecting means for detecting an electric
field transmitted after being induced in said electric field
transmission medium, and converting a change of said electric field
into an electric signal; a band pass filter that passes only a
signal component having a predetermined band containing said two
electric signals out of electric signals obtained by said electric
field detecting means; and position conversion processing means for
referring to said memory means and obtaining positional information
corresponding to the information based on said two electric signals
that pass said band pass filter.
[0057] A fifteenth aspect of the present invention provides the
transceiver according to the fourteenth aspect of the invention,
wherein said memory means stores information based on signal
intensity of two electric signals and positional information
determined according to the signal intensity information, by
relating these pieces of information to each other, said band pass
filter includes: a first band pass filter that passes only a signal
component having a first band containing one of said electric
signals obtained by said electric field detecting means; and a
second band pass filter that passes only a signal component having
a second band different from said first band containing the other
of said electric signals obtained by said electric field detecting
means, said transceiver further comprising signal intensity
measuring means for measuring signal intensity of a signal
component which passes through said first band pass filter and
signal intensity of a signal component which passes through said
second band pass filter, wherein said position conversion
processing means refers to said memory means and obtains positional
information corresponding to the information based on signal
intensity of the signal component which passes through said first
band pass filter and signal intensity of the signal component which
passes through said second band pass filter measured by said signal
intensity measuring means.
[0058] A sixteenth aspect of the present invention provides the
transceiver according to the fifteenth aspect of the invention,
wherein said memory means stores information of an intensity
difference between electric signals and positional information
determined according to the information, by relating these pieces
of information to each other, and said position conversion
processing means calculates a difference between intensity of the
signal component which passes through said first band pass filter
and intensity of the signal component which passes through said
second band pass filter measured by said signal intensity measuring
means, refers to said memory means, and obtains the positional
information corresponding to the intensity difference.
[0059] A seventeenth aspect of the present invention provides the
transceiver according to the sixteenth aspect of the invention,
wherein an external device can rewrite the relation between the
information of the intensity difference and the positional
information stored in said memory means.
[0060] An eighteenth aspect of the present invention provides the
transceiver according to the fifteenth aspect of the invention,
wherein said memory means stores information of an intensity ratio
between electric signals and positional information determined
according to the intensity ratio information, by relating these
pieces of information to each other, and said position conversion
processing means calculates a ratio of intensity of the signal
component which passes through said first band pass filter to
intensity of the signal component which passes through said second
band pass filter measured by said signal intensity measuring means,
refers to said memory means, and obtains the positional information
corresponding to the intensity ratio.
[0061] A nineteenth aspect of the present invention provides the
transceiver according to the eighteenth aspect of the invention,
wherein an external device can rewrite the relation between the
information of the intensity ratio and the positional information
stored in said memory means.
[0062] A twentieth aspect of the present invention provides the
transceiver according to the fourteenth aspect of the invention,
wherein said memory means stores information based on a phase
difference between two electric signals and positional information
determined according to the phase difference information, by
relating these pieces of information to each other, said band pass
filter includes: a first band pass filter that passes only a signal
component having a first band containing one of said electric
signals obtained by said electric field detecting means; and a
second band pass filter that passes only a signal component having
a second band different from said first band containing the other
of said electric signals obtained by said electric field detecting
means, the transceiver further comprising phase detecting means for
detecting a phase of the signal component which passes through said
first band pass filter and a phase of the signal component which
passes through said second band pass filter, wherein said position
conversion processing means calculates a difference between the
phase of the signal component which passes through said first band
pass filter and the phase of the signal component which passes
through said second band pass filter detected by said phase
detecting means, refers to said memory means, and obtains the
positional information corresponding to the phase difference.
[0063] A twenty first aspect of the present invention provides the
transceiver according to the twentieth aspect of the invention,
wherein an external device can rewrite the relation between the
information of the phase difference and the positional information
stored in said memory means.
[0064] In order to achieve said objects, a twenty second aspect of
the present invention provides a positional information obtaining
system including: an electric field transmission sheet that
transmits an electric charge and has any point thereon contacted by
an electric field transmission medium; a first and a second signal
generators that are disposed respectively at different positions on
said electric field transmission sheet, and induce electric fields
based on electric signals having a first band and a second band
respectively on said electric field transmission sheet; and a
transceiver that receives information based on an electric field
induced in said electric field transmission medium, thereby
receiving the information via said electric field transmission
medium, wherein said transceiver includes: memory means for storing
information based on two electric signals and positional
information determined according to the electric signal
information, by relating these pieces of information to each other;
electric field detecting means for detecting an electric field
transmitted after being induced in said electric field transmission
medium, and converting a change of said electric field into an
electric signal; a band pass filter that passes only a signal
component having a predetermined band containing said two electric
signals out of electric signals obtained by said electric field
detecting means; and position conversion processing means for
referring to said memory means and obtaining the positional
information corresponding to the information based on said two
electric signals that pass said band pass filter.
[0065] In order to achieve said objects, a twenty third aspect of
the present invention provides an information input system
including: an electric field transmission sheet that transmits an
electric charge and has any point thereon contacted by an electric
field transmission medium; a first and a second signal generators
that are disposed respectively at different positions on said
electric field transmission sheet, and induce electric fields based
on electric signals having a first band and a second band
respectively on said electric field transmission sheet; a
transceiver that receives information based on an electric field
induced in said electric field transmission medium, thereby
receiving the information via said electric field transmission
medium, said transceiver including: memory means for storing
information based on two electric signals and positional
information determined according to the electric signal
information, by relating these pieces of information to each other;
electric field detecting means for detecting an electric field
transmitted after being induced in said electric field transmission
medium, and converting a change of said electric field into an
electric signal; a band pass filter that passes only a signal
component having a predetermined band containing said two electric
signals out of electric signals obtained by said electric field
detecting means; and position conversion processing means for
referring to said memory means and obtaining the positional
information corresponding to the information based on said two
electric signals that pass said band pass filter; and a wearable
computer that has computer memory means that stores positional
information and input information corresponding to the positional
information by relating these pieces of information to each other,
refers to said computer memory means based on the positional
information input from said transceiver, and obtains the input
information.
[0066] In order to achieve said objects, a twenty fourth aspect of
the present invention provides an information input system
including: electric field inducing means that is contacted or
operated by an electric field transmission medium, and induces an
electric field in said electric field transmission medium according
to a physical quantity based on the contact or operation; a
transceiver that receives the electric field induced in said
electric field transmission medium, applies the electric field to a
polarization modulator or an optical intensity modulator,
polarization-modulates or optical intensity-modulates laser light
according to the electric field, converts the
polarization-modulated or optical intensity-modulated laser light
into an electric signal, extracts an electric signal having a
frequency component concerning a physical quantity based on said
contact or operation from the converted electric signals, and
outputs the electric signal concerning the physical quantity based
on said contact or operation; and information processing means for
inputting therein the electric signal concerning the physical
quantity based on said contact or operation from said transceiver,
and obtains information corresponding to the physical quantity
based on said contact or operation by said electric field
transmission medium.
[0067] In order to achieve said objects, a twenty fifth aspect of
the present invention provides an electric field sensor device that
modulates optical intensity of laser light based on an electric
field to be detected, thereby detecting said electric field, said
electric field sensor device having an electric field sensor unit
and a light receiving circuit, wherein said electric field sensor
unit includes: laser light emitting means; branching means for
branching a laser light emitted from said laser light emitting
means into a first laser light and a second laser light that are
different from each other; and optical intensity modulating means
with which said electric field to be detected is coupled, that
modulates the optical intensity of said first laser light based on
said coupled electric field, and said light receiving circuit
includes: first light/voltage converting means for converting the
optical intensity of said first laser light modulated by said
optical intensity modulating means into a voltage signal; a second
light/voltage converting means for converting the optical intensity
of said second laser light branched by said branching means into a
voltage signal; and differential amplifying means for
differentially amplifying the voltage signal obtained by conversion
by said first light/voltage converting means and the voltage signal
obtained by conversion by said second light/voltage converting
means.
[0068] A twenty sixth aspect of the present invention provides the
electric field sensor device according to the twenty fifth aspect
of the invention, wherein said electric field sensor unit further
includes an optical variable attenuator that attenuates the optical
intensity of said second laser light obtained by branching by said
branching means, and said second photoelectrical converting means
inputs therein said second laser light attenuated by said optical
variable attenuator.
[0069] A twenty seventh aspect of the present invention provides
the electric field sensor device according to the twenty fifth
aspect of the invention, wherein said electric field sensor unit
further includes a first optical variable attenuator that
attenuates the optical intensity of said first laser light obtained
by branching by said branching means at a predetermined rate, and a
second optical variable attenuator that attenuates the optical
intensity of said second laser light obtained by branching by said
branching means at a rate higher than an attenuation rate of said
first optical variable attenuator, said optical intensity
modulating means inputs therein said first laser light attenuated
by said first optical variable attenuator, and said second
photoelectrical converting means inputs therein said second laser
light attenuated by said second optical variable attenuator.
[0070] A twenty eighth aspect of the present invention provides the
electric field sensor device according to the twenty fifth aspect
of the invention, wherein said first light/voltage converting means
includes: first light/current converting means for converting the
optical intensity of said first laser light modulated by said
optical intensity modulating means into a current signal; a first
voltage source that applies an inverse bias voltage to said first
light/current converting means; and a first load resistor that
converts said current signal obtained by conversion by said first
light/current converting means into a voltage signal, and said
second light/voltage converting means includes: second
light/current converting means for converting the intensity of said
second laser light obtained by branching by said branching means
into a current signal; a second voltage source that applies an
inverse bias voltage to said second light/current converting means;
and a second load resistor that converts said current signal
obtained by conversion by said second light/current converting
means into a voltage signal.
[0071] A twenty ninth aspect of the present invention provides the
electric field sensor device according to the twenty eighth aspect
of the invention, wherein at least one of said first load resistor
and said second load resistor is a variable resistor.
[0072] A thirtieth aspect of the present invention provides the
electric field sensor device according to the twenty eighth aspect
of the invention, wherein at least one of said first voltage source
and said second voltage source is a variable voltage source.
[0073] A thirty first aspect of the present invention provides the
electric field sensor device according to the twenty fifth aspect
of the invention, wherein said light receiving circuit further
includes amplifying means for amplifying at least one of the
voltage signal obtained by conversion by said first light/voltage
converting means and the voltage signal obtained by conversion by
said second light/voltage converting means.
[0074] In order to achieve said objects, a thirty second aspect of
the present invention provides a transceiver that receives
information based on an electric field induced in an electric field
transmission medium, thereby receiving the information via said
electric field transmission medium, said transceiver including:
said electric field sensor device according to the twenty fifth
aspect; a signal processing circuit that at least removes a noise
from a voltage signal output from said electric field sensor
device; noise detecting means for detecting quantity of a noise
component of the voltage signal output from said signal processing
circuit; and a control signal generator that generates a control
signal to variably control a variable value of said electric field
sensor unit or said light receiving circuit based on the detection
data output from said noise detecting means.
BRIEF DESCRIPTION OF THE DRAWINGS
[0075] FIG. 1 is an image diagram of carrying out communications
between plural wearable computers via a human body.
[0076] FIG. 2 is an overall configuration diagram of a conventional
transceiver main body.
[0077] FIG. 3 is an overall configuration diagram of another
conventional transceiver main body.
[0078] FIG. 4 is a detailed configuration diagram of an electric
field sensor unit and a light receiving circuit of a conventional
(polarization modulation type) transceiver main body.
[0079] FIG. 5 is a diagram showing a waveform of an input signal of
a differential amplifier shown in FIG. 4.
[0080] FIG. 6 is a detailed configuration diagram of an electric
field sensor unit and a light receiving circuit of a conventional
(optical intensity modulation type) transceiver main body.
[0081] FIG. 7 is a principle diagram when an optical intensity
modulator used in the electric field sensor unit of the
conventional (optical intensity modulation type) transceiver main
body is an electroabsorption type.
[0082] FIG. 8 is a principle diagram when the optical intensity
modulator used in the electric field sensor unit of the
conventional (optical intensity modulation type) transceiver main
body is a Mach-Zehnder.
[0083] FIG. 9 is an image diagram showing a using state of a
combination of a transceiver and a wearable computer that are held
in a human hand.
[0084] FIG. 10 is an image diagram of a front view showing a using
state of a transceiver and a wearable computer according to a first
embodiment of the present invention.
[0085] FIG. 11 is an image diagram of a top plan view showing a
using state of the transceiver and the wearable computer according
to the first embodiment of the present invention.
[0086] FIG. 12 is a diagram showing frequency bands for information
communication, a signal generator A, and a signal generator B,
respectively.
[0087] FIG. 13 is an overall configuration diagram of a transceiver
main body within the transceiver according to the first
embodiment.
[0088] FIG. 14 is an overall configuration diagram of a transceiver
main body within a transceiver according to a second
embodiment.
[0089] FIG. 15 is a diagram showing a concrete example of an
electric field transmission sheet according to the first and the
second embodiments.
[0090] FIG. 16 is a diagram showing a concrete example of the
electric field transmission sheet according to the first and the
second embodiments.
[0091] FIG. 17 is a diagram showing a concrete example of the
electric field transmission sheet according to the first and the
second embodiments.
[0092] FIG. 18 is an overall configuration diagram of a transceiver
main body according to third to seventh embodiments of the present
invention.
[0093] FIG. 19 is a detailed configuration diagram of an electric
field sensor unit and a light receiving circuit of a transceiver
main body according to the third embodiment.
[0094] FIG. 20 is a detailed configuration diagram of an electric
field sensor unit and a light receiving circuit of a transceiver
main body according to the fourth embodiment.
[0095] FIG. 21 is a detailed configuration diagram of an electric
field sensor unit and a light receiving circuit of a transceiver
main body according to the fifth embodiment.
[0096] FIG. 22 is a detailed configuration diagram of an electric
field sensor unit and a light receiving circuit of a transceiver
main body according to the sixth embodiment.
[0097] FIG. 23 is a detailed configuration diagram of an electric
field sensor unit and a light receiving circuit of a transceiver
main body according to the seventh embodiment.
[0098] FIG. 24 is an overall configuration diagram of a transceiver
main body according to an eighth embodiment of the present
invention.
[0099] FIG. 25 is a diagram showing an equivalent circuit between a
human body, a transmitting and receiving electrode, and a
transceiver main body.
[0100] FIG. 26 is a diagram showing an equivalent circuit between a
human body, a transceiver main body, and a battery.
[0101] FIG. 27 is an overall configuration diagram of a transceiver
and a wearable computer according to a ninth embodiment of the
present invention.
[0102] FIG. 28 is a functional block diagram showing mainly a
function of the transceiver main body.
[0103] FIG. 29 is a detailed configuration diagram of an electric
field sensor device.
[0104] FIG. 30 is an image diagram showing a using state of the
transceiver and the wearable computer shown in FIG. 27.
[0105] FIG. 31 is an overall configuration diagram of a transceiver
and a wearable computer according to a tenth embodiment of the
present invention.
[0106] FIG. 32 is an overall configuration diagram of a transceiver
and a wearable computer according to an eleventh embodiment of the
present invention.
[0107] FIG. 33 is an overall configuration diagram of a transceiver
and a wearable computer according to a twelfth embodiment of the
present invention.
[0108] FIG. 34 is an overall configuration diagram of a transceiver
and a wearable computer according to a thirteenth embodiment of the
present invention.
[0109] FIG. 35 is an overall configuration diagram of a transceiver
and a wearable computer according to a fourteenth embodiment of the
present invention.
[0110] FIG. 36 is a diagram showing other embodiment of the present
invention.
[0111] FIG. 37 is a diagram showing other embodiment of the present
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0112] Exemplary embodiments (hereinafter, referred to as
"embodiments") according to the present invention are explained in
detail below with reference to the drawings.
[0113] A transceiver 3 according the embodiments of the present
invention induces an electric field based on information to be
transmitted in an electric field transmission medium (such as the
human body 100), and receives information based on an electric
field induced in the electric field transmission medium, thereby
transmitting and receiving information via the electric field
transmission medium.
[0114] First, an embodiment of a transceiver that can easily input
information to a particularly miniaturized wearable computer is
explained.
FIRST EMBODIMENT
[0115] A first embodiment is explained below with reference to the
drawings.
[0116] FIG. 10 is an image diagram of a front view showing a using
state of the transceiver 3 and the wearable computer 1 according to
the first embodiment. FIG. 11 is an image diagram of a top plan
view showing the using state.
[0117] As shown in FIG. 10, an insulating sheet 301 is adhered to a
flat surface of a table 300, and an electric field transmission
sheet 302 that can transmit an electric field is adhered to a flat
surface of the insulating sheet 301. Signal generators A and B are
disposed at different comers on the flat surface of the electric
field transmission sheet 302. As shown in FIG. 11, when the
electric field transmission sheet 302 is rectangular, these signal
generators are disposed at different optional comers.
[0118] Each of the signal generators A and B has a configuration
similar to that including the transmitter 103, the transmitting
electrode 105'a, and the insulating film 107'a as shown in FIG. 3,
and can induce an electric field based on an electric signal
concerning transmission frequencies fa and fb respectively on the
electric field transmission sheet 302 as shown in FIG. 12.
[0119] FIG. 13 is an overall configuration diagram of a transceiver
main body 30a within the transceiver 3 according to the present
embodiment.
[0120] As shown in FIG. 13, the transceiver main body 30a is
similar to the conventional transceiver main body 30' in that the
transceiver main body 30a has the I/O (input/output) circuit 101,
the transmitter 103, the transmitting electrode 105a, the
insulating films 107a and 107b, the receiving electrode 105b, the
electric field sensor device 115, the signal processing circuit
116, and the waveform shaping circuit 117. The transceiver main
body 30a according to the present embodiment further has band pass
filters 11a and 11b, signal intensity measuring units 13a and 13b,
a position conversion processor 15, and a memory 17.
[0121] The I/O circuit 101 is used for the transceiver main body
30a to input and output information (data) to and from an external
device such as the wearable computer 1. The transmitter 103
consists of a transmitter circuit that induces, based on the
information (data) output from the I/O circuit 101, an electric
field concerning this information in the human body 100. The
transmitting electrode 105a is used for the transmitter 103 to
induce an electric field in the human body 100, and is used as a
transmitting antenna. The insulating film 107a is an insulator film
disposed between the transmitting electrode 105a and the human body
100, and prevents the transmitting electrode 105a from directly
contacting the human body 100.
[0122] The receiving electrode 105b is used to receive an electric
field transmitted after being induced in the human body 100 from
the wearable computer 1 and the transceiver 3' that are mounted on
other part of the human body 100 and the PC 5 and the transceivers
3'a and 3'b, and is used as a receiving antenna. The insulating
film 107b is an insulator film disposed between the receiving
electrode 105b and the human body 100, like the insulating film
107a.
[0123] The electric field sensor device 115 has a function of
detecting an electric field received by the receiving electrode
105b, and converting this electric field into an electric signal as
reception information. The signal processing circuit 116 consists
of an amplifier 114 that amplifies an electric signal transmitted
from the electric field sensor device 115, and a band pass filter
151. This band pass filter 151 is a filter circuit having a
characteristic of limiting the band of an electric signal output
from the amplifier 114 and removes unnecessary noise and an
unnecessary signal component, thereby passing a signal component of
only a frequency band of a constant width (f1 to f2) for
information communication as shown in FIG. 12 out of the electric
signals output from the amplifier 114.
[0124] The waveform shaping circuit 117 shapes the waveform (signal
processing) of an electric signal transmitted from the signal
processing circuit 116, and supplies the processed electric signal
to the wearable computer 1 via the I/O circuit 101.
[0125] The band pass filter 11a is a filter circuit having a
characteristic of limiting the band of an electric signal output
from the amplifier 114 and removes unnecessary noise and an
unnecessary signal component, thereby passing a signal component of
only a frequency band (fa) for the signal generator A as shown in
FIG. 12 out of the electric signals output from the amplifier 114.
The signal intensity measuring unit 13a is a circuit that measures
signal intensity of an electric signal concerning the signal
component that is passed by the band pass filter 11a.
[0126] The band pass filter 11b is a filter circuit having a
characteristic of limiting the band of an electric signal output
from the amplifier 114 and removes unnecessary noise and an
unnecessary signal component, thereby passing a signal component of
only a frequency band (fb) for the signal generator B as shown in
FIG. 12 out of the electric signals output from the amplifier 114.
The signal intensity measuring unit 13b is a circuit that measures
signal intensity of an electric signal concerning the signal
component that is passed by the band pass filter 11b.
[0127] The memory 17 stores an intensity difference between two
electric signals and a specific position in a two-dimensional space
by relating these pieces of information to each other. According to
the present embodiment, an optional position on the electric field
transmission sheet 302 shown in FIG. 10 and FIG. 11 and the
intensity difference are related to each other in advance. An
external device such as the wearable computer 1 can rewrite the
relationship between the intensity difference and the specific
position stored in the memory 17, via the I/O circuit 101.
[0128] The position conversion processor 15 is a CPU (central
processing unit) or the like that calculates a difference between
the signal intensity measured by the signal intensity measuring
unit 13a and the signal intensity measured by the signal intensity
measuring unit 13b, and collates this intensity difference with the
intensity difference stored in the memory 17, thereby converting
the calculated intensity difference into a specific position in a
two-dimensional space.
[0129] A method of specifying a position using the transceiver main
body 30a and the signal generators A and B according to the present
embodiment is explained next.
[0130] As shown in FIG. 10 and FIG. 11, in the state that the
signal generators A and B are installed on the electric field
transmission sheet 302 and driven, a person who wears the wearable
computer 1 and the transceiver 3 touches a specific position
.alpha. on the electric field transmission sheet 302. As a result,
the receiving electrode 105b receives electric fields from the
signal generators A and B via the finger (human body 100) and the
insulating film 107b. The electric field sensor device 115 couples
(applies) the received electric fields to an electro-optic crystal,
not shown, of the electric field sensor device 115, converts the
electric fields into electric signals, and transmits the electric
signals to the signal processing circuit 116. The amplifier 114 of
the signal processing circuit 116 amplifies the electric signals,
and transmits the amplified electric signals to the band pass
filter 151. However, the electric signals concerning the electric
fields from the signal generators A and B do not pass through the
band pass filter 116.
[0131] The electric signals transmitted from the amplifier 114 are
also transmitted to the band pass filters 11a and 11b.
[0132] The band pass filter 11a passes the signal component of only
the band (fa) for the signal generator A out of the electric
signals concerning the electric fields from the signal generators A
and B, and transmits this signal component to the signal intensity
measuring unit 13a. The signal intensity measuring unit 13a
measures signal intensity of the electric signal concerning the
signal component that is passed by the band pass filter 11a.
[0133] On the other hand, the band pass filter 11b passes the
signal component of only the band (fb) for the signal generator B
out of the electric signals concerning the electric fields from the
signal generators A and B, and transmits this signal component to
the signal intensity measuring unit 13b. The signal intensity
measuring unit 13b measures signal intensity of the electric signal
concerning the signal component that is passed by the band pass
filter 11b.
[0134] The position conversion processor 15 calculates an intensity
difference between the signal intensity measured by the signal
intensity measuring unit 13a and the signal intensity measured by
the signal intensity measuring unit 13b, and collates this
intensity difference with the intensity difference stored in the
memory 17, thereby converting the calculated intensity difference
into the specific position .alpha. in the two-dimensional space on
the electric field transmission sheet 202.
[0135] Finally, the position conversion processor 15 transmits the
position information (data) at the specific position .alpha.
obtained by the position conversion processor 15 to the wearable
computer 1 via the I/O circuit 101.
[0136] As explained above, according to the present embodiment, the
intensity difference between the signal intensity measured by the
signal intensity measuring unit 13a and the signal intensity
measured by the signal intensity measuring unit 13b is calculated.
This intensity difference is collated with the intensity difference
stored in the memory 17, thereby converting the calculated
intensity difference into the specific position in the
two-dimensional space. With this arrangement, the positional
information at the specific position ox on the electric field
transmission sheet 302 that is touched with the finger (human body
100) can be input to the wearable computer 1 or the like.
Therefore, there is an effect that information can be easily input
to the wearable computer 1 or the like.
[0137] In the above embodiment, the position conversion processor
15 calculates the intensity difference between the signal intensity
measured by the signal intensity measuring unit 13a and the signal
intensity measured by the signal intensity measuring unit 13b. The
position conversion processor 15 may also calculate an intensity
ratio of the signal intensity measured by the signal intensity
measuring unit 13a to the signal intensity measured by the signal
intensity measuring unit 13b. In this case, the memory 17 needs to
store the intensity ratio between the two electric signals and the
specific position in the two-dimensional space by relating these
pieces of information to each other.
SECOND EMBODIMENT
[0138] A second embodiment is explained with reference to the
drawings.
[0139] FIG. 14 is an overall configuration diagram of a transceiver
main body 30b within a transceiver according to the second
embodiment. Constituent parts that are identical with those
according to the first embodiment are assigned with same reference
numerals, and their explanation is omitted.
[0140] A phase detector 23a shown in FIG. 14 is a circuit that
detects a phase of an electric signal concerning a signal component
which is passed by the band pass filter 11a.A phase detector 23b is
a circuit that detects a phase of an electric signal concerning a
signal component which is passed by the band pass filter 11b.
[0141] A memory 27 stores a phase difference between two electric
signals and a specific position in a two-dimensional space by
relating these pieces of information to each other. According to
the present embodiment, an optional position on the electric field
transmission sheet 302 shown in FIG. 10 and FIG. 11 and the phase
difference are related to each other in advance. An external device
such as the wearable computer 1 can rewrite the relationship
between the phase difference and the specific position stored in
the memory 27, via the I/O circuit 101.
[0142] A position conversion processor 25 is a CPU or the like that
calculates a difference between the phase measured by the phase
detector 23a and the phase measured by the phase detector 23b, and
collates this phase difference with the phase difference stored in
the memory 27, thereby converting the calculated phase difference
into a specific position in a two-dimensional space.
[0143] A method of specifying a position using the transceiver 30b
and the signal generators A and B according to the present
embodiment is explained next.
[0144] As shown in FIG. 10 and FIG. 11, in the state that the
signal generators A and B are installed on the electric field
transmission sheet 302 and driven, a person who wears the wearable
computer 1 and the transceiver 3 touches the specific position
.alpha. on the electric field transmission sheet 302. As a result,
the receiving electrode 105b receives electric fields from the
signal generators A and B via the finger (human body 100) and the
insulating film 107b. The electric field sensor device 115 couples
(applies) the received electric fields to an electro-optic crystal,
not shown, of the electric field sensor device 115, converts the
electric fields into electric signals, and transmits the electric
signals to the signal processing circuit 116. The amplifier 114 of
the signal processing circuit 116 amplifies the electric signals,
and transmits the amplified electric signals to the band pass
filter 151. However, the electric signals concerning the electric
fields from the signal generators A and B do not pass through the
band pass filter 151.
[0145] The electric signals transmitted from the amplifier 114 are
also transmitted to the band pass filters 11a and 11b.
[0146] The band pass filter 11a passes the signal component of only
the band (fa) for the signal generator A out of the electric
signals concerning the electric fields from the signal generators A
and B, and transmits this signal component to the phase detector
23a. The phase detector 23a detects a phase of the electric signal
concerning the signal component that is passed by the band pass
filter 11a.
[0147] On the other hand, the band pass filter 11b passes the
signal component of only the band (fb) for the signal generator B
out of the electric signals concerning the electric fields from the
signal generators A and B, and transmits this signal component to
the phase detector 23b. The phase detector 23b detects a phase of
the electric signal concerning the signal component that is passed
by the band pass filter 11b.
[0148] The position conversion processor 25 calculates a phase
difference between the phase measured by the phase detector 23a and
the phase measured by the phase detector 23b, and collates this
phase difference with the phase difference stored in the memory 27,
thereby converting the calculated phase difference into the
specific position ox in the two-dimensional space on the electric
field transmission sheet 302.
[0149] Finally, the position conversion processor 25 transmits the
position information (data) at the specific position .alpha.
obtained by the position conversion processor 25 to the wearable
computer 1 via the I/O circuit 101.
[0150] As explained above, according to the present embodiment,
effect similar to that according to the first embodiment is
obtained.
[0151] Concrete examples according to the first and the second
embodiments are explained below with reference to FIG. 15 to FIG.
17.
FIRST EXAMPLE
[0152] FIG. 15 and FIG. 16 show an example that the above
embodiments are applied to an electric field transmission sheet
302a and a keyboard of a personal computer. As shown in FIG. 15, a
picture of a keyboard is printed on the electric field transmission
sheet 302a. When a person touches a specific position .alpha.1, it
is possible to specify the touched key based on respective
distances x1 and y1 from the signal generators A and B.
[0153] As described above, positional information, that is, the
distances x1 and y1 from the signal generators A and B respectively
in this case, is transmitted from the transceiver 3 to the wearable
computer 1. The wearable computer 1 has a table showing a
relationship between the positional information and the input
information that is the same as the relationship between the
position on the electric field transmission sheet 302a and the
print information at this position. As a result, the wearable
computer 1 can understand the information that the person intends
to indicate.
SECOND EXAMPLE
[0154] FIG. 17 shows an example that the above embodiments are
applied to an electric field transmission sheet 302b such as a
touch panel, a touch screen, and a showcase. Similarly, when a
person touches a specific position (x2, for example, it is possible
to specify the touched position based on respective distances x2
and y2 from the signal generators A and B
[0155] According to the above embodiments, "two signal generators"
and "an electric field transmission sheet" are used. When a person
touches the electric field transmission sheet with a hand (finger),
electric signals from the two signal generators are transmitted to
a transceiver via the hand (human body 100). The transceiver
separates the two electric signals, and obtains information about
distances from the two signal generators to the touched position,
based on the two electric signals. The gist of the present
invention is not limited to this.
[0156] For example, the present invention can be applied not only
to a two-dimensional plane surface but also to a three-dimensional
space. In other words, when "three signal generators" and a
three-dimensional "electric field transmission medium" are used,
the three signal generators can transmit signals to a finger that
indicates a certain three-dimensional point via the electric field
transmission medium. The transceiver can separate the three
signals. As a result, the transceiver obtains positional
information of the point indicated by the person within a
three-dimensional space. This information is transmitted to an
information device such as a wearable computer. When a person
indicates a certain point within a three-dimensional space, the
intended information can be input to the information device.
[0157] When the transceiver has a sufficient processing speed, the
transceiver can understand the information of the position of a
finger as information about the move of the finger. In other words,
for example, when the electric field transmission sheet is touched
with the finger, the transceiver can understand the move of the
finger in real time. When this information is transmitted to an
information device such as a wearable computer, the move
information itself or information relevant to the move information
intended by a person can be input to the information device.
[0158] The information transmitted to the transceiver via the human
body is not limited to a signal based on which a position (speed)
can be obtained. For example, when the electric field transmission
sheet has a function of detecting a pressure, the pressure signal
can be also converted into an electric field, and can be
transmitted to the transceiver via a finger or the like. In this
case, the transceiver can obtain the information of pressing force
that a person intends. When this information is transmitted to an
information device such as a wearable computer, the information
device can obtain information corresponding to the pressing
force.
[0159] While it is explained above that the information device such
as a wearable computer has information corresponding to position
information or pressure information intended by a person, the
transceiver itself may have this information. With this
arrangement, the transceiver itself can obtain information intended
by a person. Alternatively, a third device other than the
information device such as a wearable computer and the transceiver
can have this information, and the information device and the
transceiver can obtain the information from this third device.
[0160] An embodiment of a transceiver that employs an optical
intensity modulator in the electric field sensor unit is explained
next.
THIRD EMBODIMENT
[0161] An electric field sensor device 115a, and an optical
intensity modulation transceiver (hereinafter simply referred to as
a "transceiver") 3 having the electric field sensor device 115a
according to a third embodiment of the present invention are
explained with reference to FIG. 18 and FIG. 19.
[0162] FIG. 18 is an overall configuration diagram of a transceiver
main body 30c that is used to carry out data communications via the
human body 100. FIG. 18 is an overall configuration diagram common
to the third to seventh embodiments.
[0163] As shown in FIG. 18, the transceiver main body 30c has the
I/O (input/output) circuit 101, the transmitter 103, the
transmitting electrode 105a, the receiving electrode 105b, the
insulating films 107a and 107b, the electric field sensor device
115 (the electric field sensor unit 110, and a light receiving
circuit 152), the signal processing circuit 116, and the waveform
shaping circuit 117.
[0164] The I/O circuit 101 is used for the transceiver main body 3c
to input and output information (data) to and from an external
device such as the wearable computer 1. The transmitter 103
consists of a transmitter circuit that induces, based on the
information (data) output from the I/O circuit 101, an electric
field concerning this information in the human body 100. The
transmitting electrode 105a is used for the transmitter 103 to
induce an electric field in the human body 100, and is used as a
transmitting antenna. The receiving electrode 105b is used to
receive an electric field transmitted after being induced in the
human body 100 from the wearable computer 1 and the transceiver 3'
that are mounted on other part of the human body 100 and the PC 5
and the transceivers 3'a and 3'b, and is used as a receiving
antenna.
[0165] The insulating film 107a is an insulator film disposed
between the transmitting electrode 105a and the human body 100, and
prevents the transmitting electrode 105a from directly contacting
the human body 100. The insulating film 107b is an insulator film
disposed between the receiving electrode 105b and the human body
100, and prevents the receiving electrode 105b from directly
contacting the human body 100.
[0166] The electric field sensor unit 110 that constitutes the
electric field sensor device 115 has a function of applying an
electric field received by the receiving electrode 105b to the
laser light, thereby changing the optical intensity of the laser
light.
[0167] The light receiving circuit 152 that constitutes the
electric field sensor device 115 has a function of receiving the
laser light of which optical intensity is changed, converting the
laser light into an electric signal, and performing signal
processing such as amplification of this electric signal. The
signal processing circuit 116 consists of at least a band pass
filter. This band pass filter removes a frequency component other
than a frequency component concerning reception information as an
electric field to be detected among electric signals having various
frequencies (that is, takes out only the frequency component
concerning the reception information), thereby performing signal
processing such as removal of noise from the electric signal.
[0168] The waveform shaping circuit 117 shapes the waveform (signal
processing) of an electric signal transmitted from the signal
processing circuit 116, and supplies the processed electric signal
to the wearable computer 1 via the I/O circuit 101.
[0169] The electric field sensor device 115a according to the third
embodiment as one example of the electric field sensor device 115
is explained in detail with reference to FIG. 19. The electric
field sensor device 115a according to the present embodiment has an
electric field sensor unit 110a as one example of the electric
field sensor unit 110, and a light receiving circuit 152a as one
example of the light receiving circuit 152. The electric field
sensor device 115a is provided in the transceiver main body 30c as
one example of the transceiver main body 30.
[0170] The electric field sensor unit 110a according to the present
embodiment consists of the current source 119, the laser diode 121,
the lens 133, a beam splitter 139, the optical intensity modulator
124, and the first and the second lenses 141a and 141b.
[0171] The optical intensity modulator 124 is configured to change
the optical intensity of light that passes depending on the
electric field intensity to be coupled. The first electrode 125 and
the second electrode 127 are provided on both side surfaces of the
optical intensity modulator 124, that are opposite in a vertical
direction in the drawing. The first electrode 125 and the second
electrode 127 sandwich from both sides the proceeding direction of
the laser light from the laser diode 121 within the optical
intensity modulator 124, and can couple the electric field with the
laser light at a right angle.
[0172] The electric field sensor unit 110a is connected to the
receiving electrode 105b via the first electrode 125. The second
electrode 127 that is opposite to the first electrode 125 is
connected to a ground electrode 131, and functions as a ground
electrode to the first electrode 125. The receiving electrode 105b
detects an electric field that is transmitted after being induced
in the human body 100, transmits this electric field to the first
electrode 125, and can couple the electric field with the optical
intensity modulator 124 via the first electrode 125.
[0173] The laser light that is output from the laser diode 121
based on the current control by the current source 119 is made
parallel light via the lens 133. The parallel laser light is
incident to the beam splitter 139. The beam splitter 139 is an
optical system that branches the incident laser light into two
laser lights and outputs the branched lights. A first laser light
obtained by the branching by the beam splitter 139 is incident to
the first lens 141a via the optical intensity modulator 124. A
second laser light obtained by the branching by the beam splitter
139 is incident to the second lens 141b not via the optical
intensity modulator 124.
[0174] The light receiving circuit 152a has a first set including
the first photodiode 143a that converts the first laser light into
a current signal according to the optical intensity of the first
laser light of which optical intensity is modulated by the optical
intensity modulator 124, the first constant voltage source 147a
that applies an inverse bias voltage to the first photodiode 143a,
and the first load resistor 145a that converts the current signal
obtained by conversion by the first photodiode 143a into a voltage
signal, and a second set including the second photodiode 143b that
converts the second laser light into a current signal according to
the optical intensity of the second laser light received via the
second lens 141b, the second constant voltage source 147b that
applies an inverse bias voltage to the second photodiode 143b, and
the second load resistor 145b that converts the current signal
obtained by conversion by the second photodiode 143b into a voltage
signal.
[0175] With this arrangement, the first photodiode 143a receives
the first laser light that passes through the optical intensity
modulator 124 and the first lens 141a of the electric field sensor
unit 110a, and the first set outputs a voltage signal (including a
signal component) as a result. The second photodiode 143b receives
the second laser light that passes through the second lens 141b of
the electric field sensor unit 110a, and the second set outputs a
voltage signal (not including a signal component) containing noise
of the laser light as a result.
[0176] The light receiving circuit 152a also has the differential
amplifier 112 that differentially amplifies a voltage signal
obtained by conversion by the first load resistor 145a and a
voltage signal obtained by conversion by the second load resistor
145b. The differential amplifier 112 differentially amplifies the
voltage signals, and supplies the output to the signal processing
circuit 116 shown in FIG. 18.
[0177] As explained above, according to the present embodiment,
laser light is branched immediately before the laser light is
incident to the optical intensity modulator 124. One laser light is
input to the optical intensity modulator 124, and is used as laser
light (including a signal component) for detecting an electric
field. The other laser light is not input to the optical intensity
modulator 124, and is used as laser light (not including a signal
component) for only removing noise from the laser light. Therefore,
it is possible to remove noise from the laser light even when the
optical intensity modulator 124 is used that cannot differentially
take out an intensity modulation signal unlike the polarization
modulator 123 that converts a polarization change of the laser
light into an intensity change.
FOURTH EMBODIMENT
[0178] An electric field sensor device 115b, and the optical
intensity modulation transceiver 3 having the electric field sensor
device 115b according to a fourth embodiment of the present
invention are explained with reference to FIG. 20.
[0179] The electric field sensor device 115b according to the
present embodiment has the following electric field sensor unit
110b in place of the electric field sensor unit 110a of the
electric field sensor device 115a according to the third
embodiment. Constituent parts of the electric field sensor unit
110b that are identical with those of the electric field sensor
unit 110a are assigned with the same reference numerals, and their
explanation is omitted. Since the light receiving circuit 152a
according to the present embodiment has the same configuration as
that of the light receiving circuit 152a according to the first
embodiment, explanation of the light receiving circuit 152a is
omitted.
[0180] As shown in FIG. 20, the electric field sensor unit 110b
according to the present embodiment has a first optical variable
attenuator 134A inserted between the beam splitter 139 and the
optical intensity modulator 124, and has a second optical variable
attenuator 134B inserted between the beam splitter 139 and the
second lens 141b. The first and the second optical variable
attenuators 134A and 134B attenuate the optical intensity of laser
light by a predetermined rate.
[0181] However, of the two laser lights obtained by branching by
the beam splitter 139, the first laser light passes through the
optical intensity modulator 124, but the second laser light does
not pass through the optical intensity modulator 124. Since
transmission efficiency of the second laser light is higher than
that of the first laser light, both transmission efficiencies need
to be balanced. According to the present embodiment, attenuation of
the second optical variable attenuator 134B through which the
second laser light passes is set larger than attenuation of the
first optical variable attenuator 134A through which the first
laser light passes.
[0182] With this arrangement, the first optical variable attenuator
134A attenuates the optical intensity of the first laser light
obtained by branching by the beam splitter 139, and then the first
photodiode 143a converts the first laser light into a current
signal. The second optical variable attenuator 134B attenuates the
optical intensity of the second laser light obtained by branching
by the beam splitter 139, and then the second photodiode 143b
converts the second laser light into a current signal. The
attenuation of the laser light that passes through the first
optical variable attenuator 134B is larger than the attenuation of
the laser light that passes through the second optical variable
attenuator 134A.
[0183] As explained above, according to the present embodiment,
noise is removed from the laser light, by inserting the first and
the second optical variable attenuators 134A and 134B. Therefore,
input signals to the differential amplifier 112 can be balanced
even when the laser light is branched.
[0184] When the second optical variable attenuator 134B by itself
can balance input signals to the differential amplifier 112, the
first optical variable attenuator 134A can be omitted.
FIFTH EMBODIMENT
[0185] An electric field sensor device 115c, and the optical
intensity modulation transceiver 3 having the electric field sensor
device 115c according to a fifth embodiment of the present
invention are explained with reference to FIG. 21.
[0186] The electric field sensor device 115c according to the
present embodiment has the following light receiving circuit 152b
in place of the light receiving circuit 152a of the electric field
sensor device 115a according to the third embodiment. Constituent
parts of the light receiving circuit 152b that are identical with
those of the light receiving circuit 152a are assigned with the
same reference numerals, and their explanation is omitted. Since
the electric field sensor unit 110a according to the present
embodiment has the same configuration as that of the electric field
sensor unit 110a according to the first embodiment, explanation of
the electric field sensor unit 110a is omitted.
[0187] As shown in FIG. 21, in place of the first and the second
load resistors 145a and 145b according to the third embodiment, the
light receiving circuit 152b according to the present embodiment
has first and second variable load resistors 145A and 145B
respectively. The first and the second variable load resistors 145A
and 145B have variable load resistances, and the resistance of the
second variable load resistor 145B is set larger than that of the
first variable load resistor 145A.
[0188] With this arrangement, voltage signals that are output from
the first photodiode 143a and the second photodiode 143b can have
the same signal intensity.
[0189] As explained above, according to the present embodiment, in
place of the first and the second load resistors 145a and 145b
according to the first embodiment, the light receiving circuit 152b
has the first and the second variable load resistors 145A and 145B
respectively, thereby removing noise from the laser light.
Therefore, input signals to the differential amplifier 112 can be
balanced even when the laser light is branched.
[0190] When input signals to the differential amplifier 112 can be
balanced using only one of the first and the second variable load
resistors 145A and 145B, one of these variable load resistors can
be omitted.
SIXTH EMBODIMENT
[0191] An electric field sensor device 115d, and the optical
intensity modulation transceiver 3 having the electric field sensor
device 115d according to a sixth embodiment of the present
invention are explained with reference to FIG. 22.
[0192] The electric field sensor device 115d according to the
present embodiment has the following light receiving circuit 152c
in place of the light receiving circuit 152a of the electric field
sensor device 115a according to the third embodiment. Constituent
parts of the light receiving circuit 152c that are identical with
those of the light receiving circuit 152a are assigned with the
same reference numerals, and their explanation is omitted. Since
the electric field sensor unit 110a according to the present
embodiment has the same configuration as that of the electric field
sensor unit 110a according to the first embodiment, explanation of
the electric field sensor unit 110a is omitted.
[0193] As shown in FIG. 22, in place of the first and the second
constant voltage sources 147a and 147b according to the third
embodiment, the light receiving circuit 152c according to the
present embodiment has first and second variable voltage sources
147A and 147B respectively. The first and the second variable
voltage sources 147A and 147B have variable voltages, and the
voltage of the second variable voltage source 147B is set smaller
than that of the first variable voltage source 147A.
[0194] With this arrangement, voltage signals that are output from
the first photodiode 143a and the second photodiode 143b can have
the same signal intensity.
[0195] As explained above, according to the present embodiment, in
place of the first and the second constant voltage sources 147a and
147b according to the third embodiment, the light receiving circuit
152c has the first and second variable voltage sources 147A and
147B respectively, thereby removing noise from the laser light.
Therefore, input signals to the differential amplifier 112 can be
balanced even when the laser light is branched.
[0196] When input signals to the differential amplifier 112 can be
balanced using only one of the first and the second variable
voltage sources 147A and 147B, one of these variable voltage
sources can be omitted.
SEVENTH EMBODIMENT
[0197] An electric field sensor device 115e, and the optical
intensity modulation transceiver 3 having the electric field sensor
device 115e according to a seventh embodiment of the present
invention are explained with reference to FIG. 23.
[0198] The electric field sensor device 115e according to the
present embodiment has the following light receiving circuit 152d
in place of the light receiving circuit 152a of the electric field
sensor device 115a according to the third embodiment. Constituent
parts of the light receiving circuit 152d that are identical with
those of the light receiving circuit 152a are assigned with the
same reference numerals, and their explanation is omitted. Since
the electric field sensor unit 110a according to the present
embodiment has the same configuration as that of the electric field
sensor unit 110a according to the first embodiment, explanation of
the electric field sensor unit 110a is omitted.
[0199] As shown in FIG. 23, there are provided a first and a second
variable gain amplifiers 149A and 149B that amplify voltage signals
output from the first and the second photodiodes 143a and 143b
respectively before these voltage signals are input to the
differential amplifier 112. The first and the second variable gain
amplifiers 149A and 149B have variable voltage gains, and the
voltage gain of the second variable gain amplifier 149B is set
smaller than that of the first variable gain amplifier 149A.
[0200] With this arrangement, voltage signals that are output from
the first photodiode 143a and the second photodiode 143b can have
the same signal intensity.
[0201] As explained above, according to the present embodiment,
there are provided the first and the second variable gain
amplifiers 149A and 149B that amplify voltage signals output from
the first and the second photodiodes 143a and 143b respectively
before these voltage signals are input to the differential
amplifier 112, thereby removing noise from the laser light.
Therefore, input signals to the differential amplifier 112 can be
balanced even when the laser light is branched.
[0202] When input signals to the differential amplifier 112 can be
balanced using only one of the first and the second variable gain
amplifiers 149A and 149B, one of these variable gain amplifiers can
be omitted.
[0203] For the optical intensity modulators according to the third
to the seventh embodiments, an electroabsorption (EA) optical
intensity modulator, a Mach-Zehnder optical intensity modulator,
and the like can be employed as in the conventional practice.
EIGHTH EMBODIMENT
[0204] A transceiver main body 30d of a transceiver according to an
eighth embodiment of the present invention is explained with
reference to FIG. 24.
[0205] The transceiver main body 30d according to the present
embodiment has an overall configuration as shown in FIG. 24. The
transceiver main body 30d excluding an electric field sensor device
215, a noise detector 218, and a control signal generator 219 has
the same configuration as that of the transceiver main body 30c
according to the third embodiment, and therefore, identical parts
are assigned with the same reference numerals and their explanation
is omitted.
[0206] The transceiver main body 30d according to the present
embodiment uses any one of the electric field sensor devices 115b
to 115e according to the fourth to the seventh embodiments, for the
electric field sensor device 215. The transceiver main body 30d
includes the noise detector 218 that detects a magnitude of noise
of a voltage signal output from the signal processing circuit 116,
and the control signal generator 219 that generates a control
signal to variably control variable values of the electric field
sensor unit 110 and the light receiving circuit 152 that constitute
the electric field sensor device 215, based on detection data
output from the noise detector 218. The noise detector 218 detects
a level of noise that remains in the electric signal output from
the signal processing circuit 116, that is, a level of noise that
is present in a frequency band concerning reception information as
an electric field to be detected.
[0207] The "variable value" means the following in respective
embodiments. According to the fourth embodiment (FIG. 20), the
variable value means attenuation of the optical intensity of the
first and the second optical variable attenuators 134A and 134B.
According to the fifth embodiment (FIG. 21), the variable value
means resistance of the first and the second variable load
resistors 145A and 145B. According to the sixth embodiment (FIG.
22), the variable value means a voltage of the first and the second
variable voltage sources 147A and 147B. According to the seventh
embodiment (FIG. 23), the variable value means a voltage gain of
the first and the second variable gain amplifiers 113A and
113B.
[0208] As explained above, according to the present embodiment,
there is an effect that, even after the transceiver main body 30d
is manufactured, a variable value can be automatically changed and
adjusted.
[0209] Next, an embodiment of a transceiver is explained, the
transceiver including a transceiver main body that can transmit and
receive information via an electric field transmission medium, a
battery that drives the transceiver main body, and an insulating
case that covers the transceiver main body, and the transceiver
being of a type that a human body (hand) as the electric field
transmission medium contacts a wide surface of an external wall
surface.
[0210] The main point of the embodiment of the transceiver is
explained first. Regarding the transceiver and the wearable
computer shown in FIG. 9, the equivalent circuit between the human
body (hand), the transmitting and receiving electrode, the
transceiver main body, and the battery is considered.
[0211] FIG. 25 is a diagram showing an equivalent circuit between a
human body, a transmitting and receiving electrode, and a
transceiver main body.
[0212] In FIG. 9, the human body 100 and the transmitting and
receiving electrode 105' are separated by the insulating film 107'.
Therefore, impedance between the human body 100 and the
transmitting and receiving electrode 105 can be expressed by the
equivalent circuit as shown in FIG. 25.
[0213] In order to realize highly reliable communications via the
human body 100, an induced alternate current electric field
(frequency f) to the human body 100 needs to be large. In order to
increase the induced alternate current electric field (frequency
f), the impedance between the human body 100 and the transmitting
and receiving electrode 105 needs to be small. As shown in FIG. 25,
a resistance component of the impedance between the human body 100
and the transmitting and receiving electrode 105 is considered very
large. Therefore, in order to make the impedance small, the
capacitance component needs to be set large.
[0214] In order to increase the capacitance component, it is
effective to use a material having a large dielectric constant for
the insulating film 107 or decrease the thickness of the insulating
film 107. It is also effective to have a large area of the
transmitting and receiving electrode 105 to indirectly face the
human body over a wide range.
[0215] However, when the insulating film 107 is too thin, there is
a high possibility that the human body 100 directly touches the
transmitting and receiving electrode 105, and a risk that a large
current flows to the human body 100 increases. Therefore, when the
area of the transmitting and receiving electrode 105 is increased,
the capacitance can be increased while securing safety, which is
preferable. When the transmitting and receiving electrode 105 is
made large, a shielding effect can be expected.
[0216] FIG. 26 is a diagram showing an equivalent circuit between a
human body, a transceiver main body, and a battery.
[0217] In order to realize highly reliable communications via the
human body 100, it is necessary to avoid inducing an unnecessary
alternate current electric field (frequency f) between the human
body 100, the transceiver main body 30, and the battery 6. For this
purpose, impedance between these items needs to be increased,
thereby decreasing mutual coupling capacitance.
[0218] When an insulator is interposed between the items, and in
order to increase this effect, it is necessary to use an insulator
having a small dielectric constant, or decrease an area of contact
between the insulator, the human body 100, the transceiver main
body 30, and the battery 6, or increase the thickness of the
insulator.
[0219] From the above viewpoint, the following embodiment is
considered to carry out secure and highly reliable communications
via the human body in the transceiver shown in FIG. 9.
NINTH EMBODIMENT
[0220] A ninth embodiment is explained below with reference to FIG.
27 to FIG. 30.
[0221] FIG. 27 is an overall configuration diagram of a transceiver
3a and the wearable computer 1 according to a ninth embodiment of
the present invention. FIG. 28 is a functional block diagram
showing mainly a function of the transceiver main body 30. FIG. 29
is a detailed configuration diagram of an electric field sensor
device 115'. FIG. 30 is an image diagram showing a using state of
the transceiver 3a and the wearable computer 1 shown in FIG.
27.
[0222] As shown in FIG. 27, the transceiver 3a consists of the
insulating case 33 formed with an insulator, a device incorporated
in the insulating case 33, and the following members attached to
the outside of the insulating case 33.
[0223] An insulating foam member 7a that weakens electric coupling
between the insulating case 33 and the transceiver main body 30 is
attached to the bottom of the internal wall surface of the
insulating case 33. The transceiver main body 30 that carries out
transmission and reception of data (information) to and from the
wearable computer 1 is attached to the upper surface of the
insulating foam member 7a. An insulating foam member 7b that
weakens electric coupling between the transceiver main body 30 and
the battery 6 is attached to the upper surface of the transceiver
main body 30. The battery 6 that drives the transceiver 30 is
attached to the upper surface of the insulating foam member 7b. In
other words, the insulating foam member 7a is sandwiched (supported
in a sandwiched state) between the insulating case 33 and the
transceiver main body 30, and the insulating foam member 7b is
sandwiched between the transceiver main body 30 and the battery 6.
The insulating foam members 7a and 7b are formed with numerous
holes containing air. Therefore, the insulating foam member 7a can
restrict transmission of noise between the insulating case 33 and
the transceiver main body 30. The insulating foam member 7b can
restrict transmission of noise between the transceiver main body 30
and the battery 6.
[0224] A first ground electrode 131 described later is extended
from the transceiver main body 30, and is attached to an upper part
of the internal wall surface of the insulating case 33 apart from
the transmitting and receiving electrode 105 in a state that the
first ground electrode 131 is not in contact with other devices
(such as the battery 6, and the wearable computer 1). A second
ground electrode 161 and a third ground electrode 163 described
later are extended from the transceiver main body 30, and are
attached to an upper part of the internal wall surface of the
insulating case 33 apart from the transmitting and receiving
electrode 105 in a state that these ground electrodes are not in
contact with other devices (such as the battery 6, and the wearable
computer 1) and the first ground electrode 131.
[0225] The transmitting and receiving electrode 105 is attached to
the bottom of the external wall surface and the side of the
external wall surface of the insulating case 33, thereby covering
the whole of the transmitting and receiving electrode 105 with the
insulating film 107. Parts other than the operation/input surface
of the wearable computer 1 are covered with the insulating case
11.
[0226] The transceiver main body 30 is similar to the conventional
transceiver main body 30' in that the transceiver main body 30 has
the I/O (input/output) circuit 101, the transmitter 103, the
transmitting and receiving electrode 105, the insulating film 107,
the electric field sensor device 115', and the receiving circuit
113 (the signal processing circuit 116, and the waveform shaping
circuit 117). These configurations are explained below.
[0227] The I/O circuit 101 is used for the transceiver main body 30
to input and output information (data) to and from an external
device such as the wearable computer 1. The transmitter 103
consists of a transmitter circuit that induces, based on the
information (data) output from the I/O circuit 101, an electric
field concerning this information in the human body 100. The
transmitting and receiving electrode 105 is used for the
transmitter 103 to induce an electric field in the human body 100,
and is used as a transmitting antenna. The transmitting and
receiving electrode 105 is also used to receive an electric field
transmitted after being induced in the human body 100, and is used
as a receiving antenna. The insulating film 107 is an insulator
film disposed between the transmitting and receiving electrode 105
and the human body 100, thereby preventing the transmitting and
receiving electrode 105 from directly contacting the human body
100.
[0228] The electric field sensor device 115' has a function of
detecting an electric field received by the transmitting and
receiving electrode 105, and converting this electric field into an
electric signal as reception information.
[0229] The signal processing circuit 116 of the receiving circuit
113 amplifies an electric signal transmitted from the electric
field sensor unit 115', limits the band of the electric signal, and
removes unnecessary noise and an unnecessary signal component.
[0230] The waveform shaping circuit 117 shapes the waveform (signal
processing) of an electric signal transmitted from the signal
processing circuit 116, and supplies the processed electric signal
to the wearable computer 1 via the I/O circuit 101. The transmitter
103, the receiving circuit 113, and the I/O circuit 101 can be
driven with the battery 6.
[0231] The electric field sensor unit 115' is explained in detail
with reference to FIG. 29. This is explained again although the
outline is already explained with reference to FIG. 4.
[0232] The electric field sensor unit 115' restores the electric
field received by the transceiver main body 30 to the electric
signal. This processing is carried out by detecting the electric
field according to an electro-optic method using laser light and an
electro-optic crystal.
[0233] As shown in FIG. 29, the electric field sensor unit 115'
consists of the current source 119, the laser diode 121, the
electro-optic element (electro-optic crystal) 123, the first and
the second wave plates 135 and 137, the polarizing beam splitter
139, the plural lenses 133, 141a, and 141b, the photodiode 143a and
143b, and the first ground electrode 131.
[0234] Of the above, the electro-optic element 123 has sensitivity
in only the electric field that is coupled in a direction
perpendicular to a proceeding direction of laser light that is
emitted from the laser diode 121. The electro-optic element 123
changes optical characteristic, that is, a birefringence index,
according to the electric field intensity, and changes the
polarization of the laser light based on the change of the
birefringence index. The first electrode 125 and the second
electrode 127 are provided on both side surfaces of the
electro-optic element 123, that are opposite in a vertical
direction in FIG. 29. The first electrode 125 and the second
electrode 127 sandwich the proceeding direction of the laser light
from the laser diode 121 in the electro-optic element 123, and can
couple the electric field with the laser light at a right
angle.
[0235] The electric field sensor unit 115' is connected to the
transmitting and receiving electrode 105 via the first electrode
125. The second electrode 127 that is opposite to the first
electrode 125 is connected to the first ground electrode 131, and
functions as a ground electrode to the first electrode 125. The
transmitting and receiving electrode 105 receives an electric field
that is transmitted after being induced in the human body 100,
transmits this electric field to the first electrode 125, and can
couple the electric field with the electro-optic element 123 via
the first electrode 125.
[0236] On the other hand, the laser light output from the laser
diode 121 according to the current control from the current source
119 is made parallel light via the lens 133. The first wave plate
135 adjusts the polarization state of the parallel laser light, and
inputs the laser light to the electro-optic element 123. The laser
light that is incident to the electro-optic element 123 is
propagated between the first and the second electrodes 125 and 127
within the electro-optic element 123. During the propagation of the
laser light, the transmitting and receiving electrode 105 receives
the electric field that is transmitted after being induced in the
human body 100 as explained above, and couples this electric field
with the electro-optic element 123 via the first electrode 125.
Then, the electric field is formed from the first electrode 125
toward the second electrode 127 connected to the ground electrode
131. Since the electric field is perpendicular to the proceeding
direction of the laser light that is incident from the laser diode
121 to the electro-optic element 123, the birefringence index as
the optical characteristic of the electro-optic element 123
changes, and the polarization of the laser light changes
accordingly.
[0237] The second wave plate 137 adjusts the polarization state of
the laser light of which polarization is changed by the electric
field from the first electrode 125 in the electro-optic element
123, and inputs the laser light to the polarizing beam splitter
139. The polarizing beam splitter 139 separates the laser light
incident from the second wave plate 137, into a P wave and an S
wave, and converts the laser light into optical intensity
change.
[0238] The first and the second lenses 141a and 141b condense
respectively the laser light that is separated into the P wave
component and the S wave component by the polarizing beam splitter
139. The first and the second photodiodes 143a and 143b receive the
laser light, convert the P wave light signal and the S wave light
signal into respective current signals, and output the current
signals. As described above, the current signals output from the
first and the second photodiodes 143a and 143b are converted into
voltage signals using resistors. Then, the signal processing
circuit 116 shown in FIG. 28 performs signal processing of
amplification of the voltage signals and removal of noise.
[0239] According to the transceiver main body 30 of the present
embodiment, the first ground electrode 131 that becomes a reference
point of voltage for the electric field sensor unit 115' is
extended to the outside of the transceiver main body 30 as shown in
FIG. 27. The second ground electrode 161 that becomes a reference
point of voltage for the signal processing circuit 116 and the
third ground electrode 163 that becomes a reference point of
voltage for the transmitter 103 are extended in common to the
outside.
[0240] A using state of the transceiver 3a and the wearable
computer 1 according to the present embodiment is explained next
with reference to FIG. 30.
[0241] As shown in FIG. 30, when the human hand (human body 100)
holds the transceiver 3a, the hand holds the bottom of the external
wall surface and the side of the external wall surface of the
insulating case 33. In this case, the transmitting and receiving
electrode 105 and the insulating film 107 cover not only the bottom
of the external wall surface but also the side of the external wall
surface of the insulating case 33. Therefore, although transmission
electric fields E1, E2, and E3 are induced from the whole of the
insulating case 33, return of a part of the electric fields from
the hand to the transceiver 3 via the side surface of the
insulating case 33 is restricted.
[0242] As explained above, according to the present embodiment, the
transmitting electrode (the transmitting and receiving electrode
105, in this case) is attached to a wide surface, including not
only the bottom surface (bottom) but also the side surface (side)
and the like, of the external wall surface of the insulating case
33, and is covered with the insulating film 107. Therefore, even
when the human hand holds the transceiver 3a, it is possible to
prevent a part of the transmission electric fields returning from
the hand back to the transceiver 3a.
[0243] Further, because the first ground electrode 131, the second
ground electrode 161, and the third ground electrode 163 are
attached to the upper parts of the internal wall surface of the
insulating case 33 apart from the transmitting and receiving
electrode 105, it is possible to prevent leakage of an unnecessary
signal from the transmitting and receiving electrode 105 to the
transceiver main body 30, and the ground can be reinforced.
[0244] Further, because the insulating foam member 7a is sandwiched
between the insulating case 33 and the transceiver main body 30,
and the insulating foam member 7b is sandwiched between the
transceiver main body 30 and the battery 6, it is possible to
restrict noise from entering the transceiver main body 30 from the
battery 6 and the insulating case 33.
TENTH EMBODIMENT
[0245] A tenth embodiment is explained below with reference to FIG.
31.
[0246] FIG. 31 is an overall configuration diagram of a transceiver
32 and the wearable computer 1 according to the tenth embodiment.
Constituent parts according to the tenth embodiment identical with
those according to the ninth embodiment are assigned with the same
reference numerals, and their explanation is omitted.
[0247] According to the present embodiment, as shown in FIG. 31,
insulating pillars 99a and 99b are employed in place of the
insulating foam members 7a and 7b according to the ninth
embodiment.
[0248] According to the present embodiment, contact areas between
the insulator, the human body 100, the transceiver main body 30,
and the battery 6 are made small, respectively. Therefore, there is
a further significant effect that an unnecessary alternate current
field is not induced.
[0249] Wooden materials other than the foamed materials may be used
for the insulating pillars 99a and 99b. However, a light and stiff
member like paulownia is preferable.
[0250] While pillars are employed in the present embodiment, a
block structure may be also employed.
ELEVENTH EMBODIMENT
[0251] An eleventh embodiment is explained below with reference to
FIG. 32.
[0252] FIG. 32 is an overall configuration diagram of a transceiver
3c and the wearable computer 1 according to the eleventh
embodiment.
[0253] According to the present embodiment, as shown in FIG. 32,
the second and the third ground electrodes 161 and 163 are extended
from the insulating case 33 of the transceiver 3c, and are attached
to the side surface (side) of the insulating case 11 of the
wearable computer 1.
[0254] As explained above, according to the present embodiment, in
addition to the effect of the ninth embodiment, the second and the
third ground electrodes 161 and 163 are positioned farther from the
transmitting and receiving electrode 105 than that according to the
ninth embodiment. Therefore, leakage of an unnecessary signal from
the transmitting and receiving electrode 105 to the transceiver
main body 30 can be prevented more securely, and the ground can be
further reinforced.
TWELFTH EMBODIMENT
[0255] A twelfth embodiment is explained below with reference to
FIG. 33.
[0256] FIG. 33 is an overall configuration diagram of a transceiver
3d and the wearable computer 1 according to the twelfth embodiment.
Constituent parts according to the twelfth embodiment identical
with those according to the ninth embodiment are assigned with the
same reference numerals, and their explanation is omitted.
[0257] According to the present embodiment, as shown in FIG. 33,
the first ground electrode 131 is extended from the insulating case
33 of the transceiver 3d, and is attached to the side surface
(side) of the insulating case 11 of the wearable computer 1.
[0258] As explained above, according to the present embodiment, in
addition to the effect of the ninth embodiment, the first ground
electrode 131 is positioned farther from the transmitting and
receiving electrode 105 than that according to the ninth
embodiment. Therefore, leakage of an unnecessary signal from the
transmitting and receiving electrode 105 to the transceiver main
body 30 can be prevented more securely, and the ground can be
further reinforced.
THIRTEENTH EMBODIMENT
[0259] A thirteenth embodiment is explained below with reference to
FIG. 34.
[0260] FIG. 34 is an overall configuration diagram of a transceiver
3e and the wearable computer 1 according to the thirteenth
embodiment. Constituent parts according to the thirteenth
embodiment identical with those according to the ninth embodiment
are assigned with the same reference numerals, and their
explanation is omitted.
[0261] According to the present embodiment, as shown in FIG. 34,
the transmitting and receiving electrode 105 is divided into a
transmitting electrode 105a exclusively used for transmission and a
receiving electrode 105b exclusively used for reception. The
transmitting electrode 105a is disposed at a position corresponding
to the transmitting and receiving electrode 105 shown in FIG. 31.
The receiving electrode 105b is disposed on an external bottom
surface of the insulating film 107a as shown in FIG. 34. The
receiving electrode 105b is also covered with the insulating film
107b to prevent the human body from being in direct contact with
the receiving electrode 105b. According to the present embodiment,
the insulating film 107 shown in FIG. 31 is expressed as the
insulating film 107a.
[0262] As explained above, according to the present embodiment, the
transmitting electrode 105a is relatively large, and covers
substantially the whole of the insulating case 33, and the
receiving electrode 105b is small. Therefore, in addition to the
effect of the ninth embodiment, there is an effect that a rate of
returning of a part of the electric fields for transmission from
the hand is small.
[0263] The layout positions of the transmitting electrode 105a and
the receiving electrode 105b may be replaced, like a transceiver 3f
shown in FIG. 35 (a fourteenth embodiment).
OTHER EMBODIMENTS
[0264] According to the eleventh and the twelfth embodiments, one
ground electrode is attached to the side surface of the insulating
case 11 of the wearable computer 1. However, the attaching mode is
not limited to this. The first ground electrode 131, and the second
and third ground electrodes 161 and 163 can be attached to the side
surface of the insulating case 11 of the wearable computer 1,
without the first ground electrode 131 contacted with the second
and third ground electrodes 161 and 163.
[0265] According to the ninth and the eleventh to the thirteenth
embodiments, the insulating foam member 7a is sandwiched between
the insulating case 33 and the transceiver main body 30, and the
insulating foam member 7b is sandwiched between the transceiver
main body 30 and the battery 6. The layout is not limited to this.
As shown in FIG. 36, an integrated insulating foam member 8 that
covers both the battery 6 and the transceiver main body 30 without
these members contacted with each other can be used. Further, as
shown in FIG. 37, a cushion insulating member 9 in which gas like
air is confined can be used instead of the foam member.
INDUSTRIAL APPLICABILITY
[0266] As explained above, according to the present invention,
there is an effect that when an electric field transmission medium
like a human body touches a position in a two-dimensional space,
information can be easily input to the wearable computer 1 and the
like via the electric field transmission medium.
[0267] Further, according to the present invention, laser light is
branched (separated) before the laser light is incident to optical
intensity modulating means. One laser light is input to the optical
intensity modulating means, and is used as laser light for
detecting an electric field. The other laser light is not input to
the optical intensity modulating means, but is used as laser light
for only removing noise from the laser light. Therefore, there is
an effect that it is possible to remove noise from the laser light
even when the optical intensity modulating means is used that
cannot differentially take out an intensity modulation signal like
the modulator that converts a polarization change of the laser
light into an intensity change.
[0268] Further, according to the present invention, the
transmitting electrode is attached to a wide surface, including not
only the bottom surface (bottom) but also the side surface (side),
of the external wall surface of the insulating case. Therefore,
even when the human hand holds the transceiver, it is possible to
prevent a part of the transmission electric fields returning from
the hand back to the transceiver.
* * * * *