U.S. patent application number 11/713727 was filed with the patent office on 2007-08-02 for electronic device using fuel cells.
Invention is credited to Tomoichi Kamo, Yasushi Muranaka, Akira Tanaka.
Application Number | 20070178344 11/713727 |
Document ID | / |
Family ID | 32040630 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070178344 |
Kind Code |
A1 |
Tanaka; Akira ; et
al. |
August 2, 2007 |
Electronic device using fuel cells
Abstract
An electronic apparatus includes a power generation panel having
a film/electrode assembly formed by joining an electrolyte film, an
anode electrode and a cathode electrode, and a fuel supply layer
for supplying fuel to the film/electrode assembly. The electronic
apparatus further includes a main body having a semiconductor
circuit for performing operational processing, and a cover member
for covering the main body. When a power supply for the electronic
apparatus is turned on, a space is provided between the power
generation panel and the main body.
Inventors: |
Tanaka; Akira; (Mito,
JP) ; Kamo; Tomoichi; (Tokai, JP) ; Muranaka;
Yasushi; (Hitachinaka, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-3873
US
|
Family ID: |
32040630 |
Appl. No.: |
11/713727 |
Filed: |
March 5, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10622553 |
Jul 21, 2003 |
7201989 |
|
|
11713727 |
Mar 5, 2007 |
|
|
|
Current U.S.
Class: |
429/429 ;
429/483; 429/513; 429/7 |
Current CPC
Class: |
G06F 1/26 20130101; G06F
1/1635 20130101; G06F 1/1637 20130101; G06F 1/1616 20130101; H01M
8/2475 20130101; Y02B 90/10 20130101; Y02E 60/50 20130101; H01M
2250/30 20130101; H01M 8/04089 20130101; H01M 8/04955 20130101 |
Class at
Publication: |
429/022 ;
429/007 |
International
Class: |
H01M 8/04 20060101
H01M008/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2002 |
JP |
2002-289363 |
Claims
1. An electronic apparatus comprising a power generation panel
having a film/electrode assembly formed by joining an electrolyte
film, an anode electrode and a cathode electrode, and a fuel supply
layer for supplying fuel to the film/electrode assembly, the
electronic apparatus further comprising a main body having a
semiconductor circuit for performing operational processing, and a
cover member for covering the main body, wherein when a power
supply for the electronic apparatus is turned on, a space is
provided between the power generation panel and the main body.
2. The electronic apparatus according to claim 1, wherein when the
power supply for the electronic apparatus is turned off, a first
distance between the power generation panel and the main body is
shorter than a second distance between the power generation panel
and the main body established when the power supply for the
electronic apparatus is turned on.
3. The electronic apparatus according to claim 1, further
comprising a fuel cell in which fuel is supplied to the power
generation panel when the power supply for the electronic apparatus
is turned on.
4. The electronic apparatus according to claim 1, further
comprising a fuel cell in which fuel is supplied to the power
generation panel when the power supply for the electronic apparatus
is turned off.
5. A fuel cell in which fuel is supplied to the power generation
panel when the power supply for the electronic apparatus according
to claim 1 is turned on.
6. A fuel cell in which supply of fuel to the power generation
panel is stopped when the power supply of the electronic apparatus
according to claim 1 is turned off.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 10/622,553, filed Jul. 21, 2003, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to an electronic device having a fuel
cell, and more particularly to an information electronic device
using a fuel cell of a type which directly oxidizes methanol.
[0003] Fuel cells have advantages of high energy efficiency in
directly taking electric energy electro-chemically from a fuel, and
eco-friendly because fuel cells' emission matter is chiefly water.
Therefore, attempts are being made to apply fuel cells to
automobiles, distributed power supplies, and information electronic
devices. Above all, for information electronic devices, fuel cells
are drawing attention as power supplies capable of long-term
continuous operation to take the place of lithium batteries, and
various kinds of information electronic devices are being devised
which are equipped with fuel cells.
[0004] For example, there are an information electronic device with
a built-in fuel cell made of hydrogen storing alloy (see
JP-A-09-213359, p. 3, FIG. 1) and an information electronic device
using a methanol fuel cell (see JP-A-2002-49440, p. 3, FIG. 2).
[0005] Among methanol fuel cells, a type which takes electricity by
direct oxidation of liquid methanol, namely, the so-called Direct
Methanol Fuel Cell hereafter referred to as DMFC has an advantage
that the fuel cell does not require an auxiliary device, such as a
reformer, therefore, the battery system is formed with relative
ease compared with fuel cell stacks.
[0006] As a fuel for the cathode, oxygen is required, and normally
air that includes oxygen is used.
[0007] Generally, with fuel cells, the larger cell surface, or, the
larger electrode surface provides greater power output. However,
because the size of electronic devices imposes a limit to the area
of the fuel cell, the fuel cell needs to be formed in a structure
that offers greater output while keeping the cubic volume
unchanged.
SUMMARY OF THE INVENTION
[0008] Therefore, according to the present invention, instead of
supplying air through one side of the casing of the fuel cell to
generate electricity as in the prior art, a fuel cell is used which
is so structured as to supply air through at least two surfaces of
the casing of the fuel cell, and supplies fuel from the inside of
the casing.
[0009] When such a fuel cell is mounted on an electronic device, it
is necessary to supply air to the two air-intake surfaces of the
casing of the fuel cell simultaneously.
[0010] The present invention has an object to provide a fuel cell
for use on an electronic device, which is so structured as to
supply air from at least two surfaces of the casing.
[0011] The fuel cell for use on an electronic device is not mounted
in the electronic device as in the conventional design. This fuel
cell is provided with an empty space for air to enter between the
fuel cell and the electronic device, and is set in a manner that
the side of the fuel cell which is opposite the side facing the
electronic device is exposed to the ambient air.
[0012] Other objects, features and advantages of the invention will
become apparent from the following description of the embodiments
of the invention taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows an external appearance of an information
electronic device provided with a fuel cell according to a first
embodiment of the present invention;
[0014] FIG. 2 is a diagram showing a cross section of the display
of the information electronic device in a power stop mode;
[0015] FIG. 3 is a diagram showing a cross section of the display
of the information electronic device in a power supply mode;
[0016] FIG. 4 is a flowchart for explaining the relation between
states of a power supply switch of the information electronic
device and operations of the fuel cell;
[0017] FIG. 5 shows a schematic cross section of the fuel cell and
the display section of an information electronic device provided
with the fuel cell according to a second embodiment of the present
invention;
[0018] FIG. 6 is a diagram showing a schematic sectional view of a
display section of an information electronic device provided with a
fuel cell according to a third embodiment of the present invention
and the fuel cell in power supply mode;
[0019] FIG. 7 is a diagram showing a schematic cross section of a
display of an information electronic device provided with a fuel
cell according to a fourth embodiment of the present invention and
the fuel cell in power supply mode; and
[0020] FIG. 8 is a schematic diagram of a cross section of the fuel
cell according to the present invention.
DESCRIPTION OF THE EMBODIMENTS
Embodiment 1
[0021] FIG. 1 shows an external appearance of an information
electronic device provided with a fuel cell according to a first
embodiment of the present invention. It is assumed that an
information electronic device according to this embodiment is a
so-called notebook computer (a personal computer) or a PDA
(Personal Digital Assistant), which comprises a main body having
semiconductor circuits for executing arithmetic operations and a
cover member (display section 2 in FIG. 2) covering the main body.
A fuel cell is composed mainly of a power generator panel 1 and a
fuel tank 3, and the whole of them all is referred to as a fuel
cell. The fuel tank 3 is a container to store a fuel to be supplied
to the power generator panel 1. The fuel tank 3 is mounted not on
the cover member (display section 2 in FIG. 2) but on the notebook
computer main body side. Further, the fuel tank 3 is not integral
with the notebook computer but is provided separately. The power
generator panel 1 includes electrodes (the anode 9 and the cathode
10 as shown in FIG. 8) and an electrolyte film (FIG. 8), and causes
a fuel to react with oxygen from the air. This power generator
panel is in a flat plate in this embodiment, and is mounted facing
the reverse side (the side without the display 12) of the display
section 2 of the information electronic device 4. In this
embodiment, an LCD screen is shown as the display 12, but the
present invention is not limited to this kind of display. The
information electronic device 4 is any of information electronic
devices other than a notebook computer as shown in FIG. 1, such as
an information electronic device which has a central processing
unit (CPU) and a display included in the same casing, and this
embodiment can be adopted in an electronic device which is provided
with a fuel cell.
[0022] FIG. 1 shows the fuel cell setting state when power is not
supplied, or, in a power stop mode, which means that this fuel cell
setting state is linked with turning off of power supply of the
information electronic device. FIG. 2 shows the cross section of
the display section 2 and the power generator panel 1 of the
information electronic device in power stop mode. In the power
generator panel 1 of the fuel cell, the surface 1a (hereafter
referred to as a first surface) on the display section side of the
information electronic device is either in contact with or very
close to the information electronic device, and the other surface
1b (hereafter referred to as a second surface) 1b opposite to the
first surface facing the display section of the information
electronic device is exposed to atmospheric air. The second surface
1b is set integrally with the information electronic device so that
the external appearance of the second surface viewed from the rear
of the display section 2 is flat. In this embodiment, the external
appearance is made to look flat as viewed from the rear of the
display section 2 in consideration of design in appearance. The
rear side 2b of the display section of the information electronic
device is in contact with the first surface 1a so that the power
generator panel 1 is integral with the information electronic
device, or the rear side of the information electronic device is
made closer to the first surface 1a than in power supply mode at
least to such an extent that air supply to the first surface 1a is
decreased or power generation efficiency is reduced, with the
result that the whole of the information electronic device 4
combining the information electronic device with the fuel cell is
reduced in thickness and improved in portability.
[0023] In addition, by providing a recessed area to accommodate the
power generator panel in the rear side 2b of the display section,
the portability is further enhanced.
[0024] FIG. 3 shows a cross section of the display section 2 and
the power generator panel 1 of the information electronic device
when power is supplied, namely, in power supply mode. This power
supply mode is linked with turning on of the information electronic
device 4. As is clear from FIGS. 2 and 3, the distance between the
power generator panel and the electronic device differs between the
power supply mode and the power stop mode. In other words, the
space between the power generator panel 1 and the information
electronic device 4 becomes wide or narrow. The distance between
the power generator panel 1 and the information electronic device 4
is put differently, the distance between an arbitrary point in the
casing of the power generator panel 1 and an arbitrary point in the
casing of the information electronic device 4. In the power
generator panel 1 of the fuel cell, by structuring the power
generator panel as shown in FIG. 3, a space is formed between the
first surface 1a and the display section 2b to supply air through
the first surface 1a. Also, the second surface 1b is exposed to
atmospheric air and the air can be supplied through this surface.
In this manner, as the power generator panel 1 of the fuel cell is
shifted from the state in FIG. 2 to the state in FIG. 3, it takes
in the air required to produce electricity through two surfaces of
the casing of the fuel cell.
[0025] The power generator panel 1 is mechanically supported on the
display section 2 through a support member 5. The support member 5
is folded (not shown) in the state shown in FIG. 2, namely, in
power stop mode, and is pulled out slidingly in power supply mode
and enters the state shown in FIG. 3. Then, the support member 5 is
slided in power stop mode and returned back to the original
position in the information electronic device, in other words,
returned to the state shown in FIG. 2. In this embodiment, the
support member 5 is formed by a resin frame. The support member 5
is a metal frame or an elastic spring-type structure. The power
generator panel 1 and the information electronic device 4 are
electrically interconnected by a cable. The power generator panel 1
is connected to a fuel tank 3 by a flexible fuel supply pipe. Thus,
when the information electronic device is changed over from the
power supply stop mode to the power supply mode and the power
generator panel 1 is moved, the electrical connection is maintained
and, since the power generator panel 1 is supported mechanically,
supply of fuel is also maintained.
[0026] The power supply to the information electronic device is
limited to a fuel cell as desired, but it is arranged that electric
power is obtained from a lithium secondary cell or an AC
adapter.
[0027] As in conventional coupling between secondary cells and
information electronic devices, the fuel cell in this embodiment is
so designed as to be electrically and mechanically removable from
information electronic devices. Therefore, when it is necessary to
change a defective fuel cell, maintenance work is easy to carry
out.
[0028] When a fuel cell in the present invention is used to replace
the existing secondary cell, the place where the existing secondary
cell is mounted is used mainly as a place to store electric
connectors (not shown) to the fuel tank or the fuel cell.
[0029] Electric connectors are preferably designed to maintain
compatibility with the secondary cell. The fuel cell comprises the
power generator panel 1 and the fuel tank 3, and the power
generator panel 1 and the fuel tank 3 are separable from each
other. The output terminal (not shown) of the power generator panel
1 is not fixed to the fuel tank 3 but it is wired to the connector
of the main body of the information electronic device.
[0030] FIG. 8 is a diagram showing a cross section of the power
generator panel 1. The power generator panel 1 comprises a
plurality of membrane-electrode assemblies (each formed by joining
together an electrolyte 8, an anode 9, and a cathode 10, and
hereafter referred to as MEA). The MEAs are incorporated in the
casing 11 of the power generator panel, and because the casing 11
has slits (not shown) formed in it, the cathode is partially
exposed to the outside. Each MEA is supplied with fuel from a fuel
supply layer 7. The fuel supply layer 7 is composed of a material
holding methanol as a fuel used in this embodiment. The material is
desirably a madreporite having a multitude of pores of a size
holding a fuel by capillary force and supplying the MEAs with a
fuel. For example, a desirable material is a metal madreporite with
methanol resistance, a ceramic madreporite or a carbon madreporite.
The madreporite with electric conductivity is insulated from the
electrodes (not illustrated). Alternatively, the madreporite is
formed of glass fiber. In the present invention, a madreporite made
of SUS was used. The fuel supply layer 7 holding a fuel is provided
to supply electricity even when the fuel tank 3 was dismounted.
This is because fuel can be held in the pores of the madreporite
for a while even when fuel supply from the fuel tank 3 was
interrupted. As the fuel supply layer 7 is larger, the power
generation time is longer after the fuel tank 3 is dismounted, but
with the information electronic device for which thinning of
product thickness is the important task, the fuel supply layer 7
was made 1 mm, which enables a minimum necessary time of 10 seconds
or longer to be secured for replacement of the fuel tank 3. As has
been described, according to the present invention, it becomes
possible to replace the fuel tank while electric connection between
the power generator panel 1 and the information device is
maintained.
[0031] The fuel tank 3 is mounted on top of the power generator
panel 1. The fuel is supplied from the fuel tank 3 by using gravity
and capillary force. Besides the top of the power generator panel
1, the fuel tank 3 is placed at the installation location for the
conventional secondary cell below the power generator panel 1. In
other words, it is placed under the palm rest or at the edge
portion of the main body of the information electronic device. In
this case, fuel transportation from the fuel tank is by capillary
force or by a small pump (not shown) built in the information
electronic device.
[0032] The connectors for electric connections are preferably
provided also for a system to transmit information about remaining
amount of the fuel in addition to a system to supply electric power
required to drive the information electronic device. In all cases,
those connectors are provided for the same kinds of systems as when
a secondary cell is used. At least one or more systems are
dedicated to supply of power and it is all very fine when multiple
systems are provided to supply power to the drive parts in the
information electronic device. It is preferable to provide a part,
such as a DC/DC converter, to change electric power produced by the
generator panel 1 to a voltage suitable for the information
electronic device, and also provide a super capacitor or an ultra
capacitor to cope with instantaneous power.
[0033] Also, it is possible to provide power supplies other than
the fuel cell, a secondary cell, for example, for use as an
auxiliary power supply for starting the information electronic
device, a power supply to cover maximum output, and another power
supply for monitoring specific events.
[0034] As shown in FIG. 4, when the power switch of the information
electronic device is turned on, the power supply mode is detected,
the power generator panel 1 of the fuel cell is separated from the
main body of the information electronic device, thereby forming a
space to supply air from, and the supply of fuel is started. The
method by which the power generator panel 1 of the fuel cell is
separated from the main body of the fuel cell is electrical or
mechanical or manual. No problem occurs when the information
electronic device enters a start-up state while the power generator
panel 1 of the fuel cell is opened manually. With information
electronic devices other than those driven solely by a fuel cell,
for example, an information electronic device, which is connected
to a fuel cell and a secondary cell or the like, is preferably
provided with a function to make a decision whether it is connected
with an AC adapter, or a conventional secondary cell or a fuel
cell, and so on, when the power switch is turned on.
[0035] To stop the information electronic device, the power switch
is turned off, at which the power stop mode is detected, and after
a specified termination process is finished, the power generator
panel 1 of the fuel cell is returned to the former position,
namely, into the state shown in FIG. 2, and is substantially in one
body with the main body of the information electronic device, and
the supply of fuel is stopped. Here, "substantially in one body"
means that it appears to be a single body. The method by which the
power generator panel 1 of the fuel cell is brought to the former
position is electrical or mechanical or manual. When the power
generator panel 1 of the fuel cell is brought manually to the
former position, the information electronic device may enter the
power stop mode. In other words, the on/off operation of the power
switch and the power supply/stop mode and the in/out action of the
power generator panel 1 may be linked.
[0036] Further, a change-over between the power supply mode and the
power stop mode is linked with the open/close action between the
display section 2 and the main body of the information electronic
device.
[0037] With the current state of technology, it is difficult for an
electrolyte as a component of the MEA to completely block the
transmission of methanol. For this reason, when a fuel, such as
methanol, directly contacts an electrolyte film 8, which is a part
of the power generator, the fuel is consumed even if the
information electronic device 4 is not operating. Therefore, in the
present invention, the supply and stoppage of the fuel is linked
with a switch-over of the power supply mode and the power stop
mode, and consumption of fuel such as methanol while the
information electronic device 4 is inoperative is minimized and
thereby the fuel is saved, namely, a substantially prolonged
operation is made possible. When, by improvement of the electrolyte
film, the transmission of fuel, such as methanol, is blocked or
substantially reduced, it is not always necessary to link supply or
stoppage of fuel with a change-over of the power supply mode and
the power stop mode.
[0038] The power generator panel 1 of the fuel cell when in power
supply mode is not necessarily required to be in parallel with the
display section 2 of the information electronic device, but the
power generator panel may be inclined to facilitate dissipation of
steam produced.
[0039] This embodiment uses a DMFC for the fuel cell, but the fuel
cell is not limited to this type. A wide range of fuel cells, such
as PEFC, may be used as long as the structure of the fuel cell is
such that air is taken from at least two surfaces of the casing of
the fuel cell. The reason for "at least" mentioned above is as
follows. Firstly, a structure is conceivable which has an MEA as an
air-inlet passage mounted at the end face of the power generator
panel 1 other than the first surface 1a and the second surface 1b,
and secondly, the structure is not necessarily a rectangular body
but may be polygonal in cross section. In this case, when a total
sum of the areas through which air is taken is large, the power
generation capacity is greater than in the case where air is taken
only from two surfaces.
[0040] The mounting location of the power generation panel 1 is not
limited to the rear of the display section 2, but may be attached
to the rear side of the information electronic device (on the
underside of the keyboard 13). In this case, legs may be attached
to the power generator panel 1 to provide a space between the
second surface 1b of the generator panel and the place where the
information electronic device is set down (on a desk, for
example).
[0041] In this embodiment, methanol is used as fuel, but it is
possible to use hydrogen or a gas containing hydrogen, a liquid
containing hydrogen atoms, such as ethanol, diethyl ether, or
ethylene glycol.
Embodiment 2
[0042] FIG. 5 shows a sectional view of the fuel cell and the
display section 2 of an information electronic device provided with
the fuel cell according to a second embodiment of the present
invention. The fuel cell comprises a fuel tank 3 and a power
generator panel 1, and the fuel tank 3 and the power generator
panel 1 are put together as one body. The fuel cell is dismounted
from the information electronic device 4. When in power supply
mode, the information electronic device is provided with a fuel
cell, and when in power stop mode in which the information
electronic device 4 is not used, such as in transit, the fuel cell
is dismounted from the information electronic device 4, and
therefore the information electronic device becomes thinner, and
the portability improves.
[0043] The power generator panel 1 is in a flat plate, and is
mounted at the rear side 2b of the information electronic device in
a manner facing the flat display section 2. A projection 6 is
formed at a part of the casing of the fuel cell to provide a space
between the information electronic device 4 and the fuel cell. This
projection may be provided on the information electronic device
side.
[0044] In the power supply mode in which the fuel cell is provided,
in the power generator panel 1 of the fuel cell, the first surface
1a is not substantially in contact with the information electronic
device, and the second surface 1b is exposed to the atmospheric
air. Therefore, the air can be taken from those two surfaces.
[0045] The fuel cell is formed by combining the fuel tank 3 and the
power generator panel 1 in a single body, with the result that the
fuel cell is simplified in structure, and made easy to manufacture
and the price can be reduced.
Embodiment 3
[0046] FIG. 6 shows a schematic cross section of the display
section 2 of the information electronic device 4 provided with a
fuel cell according to a third embodiment of the present invention
and the fuel cell in power supply mode. In the power stop mode, as
shown in FIG. 1 of the first embodiment, the power generator panel
1 of the fuel cell is in contact with and in one body with the
information electronic device. When the power switch is turned on,
the power supply mode is detected, the power generator panel 1 of
the fuel cell is separated from the information electronic device
4, by which a space is formed to supply air to the MEAs, and the
fuel begins to be supplied. As regards the shape of the space to
supply air to the power generator, as shown in FIG. 6, the power
generator panel 1 of the fuel cell is bent at least one or more
points in a so-called accordion-fold. The mechanism of this bending
may be electrical, mechanical or manual as in the first embodiment.
When the power generator panel 1 of the fuel cell is moved away
manually, the information electronic device may enter a start-up
state. The direction in which the panel is bent may be in the
horizontal direction (in the direction of the depth in FIG. 6)
other than in the vertical direction as shown in FIG. 6. When the
information electronic device 4 is stopped, the power switch is
turned off as in the first embodiment, at which the power stop mode
is detected, and when a specified termination process is finished,
the power generator panel 1 of the fuel cell is returned to the
former position, comes into contact with the information electronic
device 4, and the supply of fuel is stopped.
[0047] The method by which the power generator panel 1 of the fuel
cell is brought to the former position may be electrical,
mechanical or manual. When the power generator panel 1 of the fuel
cell is brought to the former position, the information device may
enter a power stop mode. Even when the information electronic
device is toppled over inadvertently in power supply mode, because
the power generator panel 1 of the fuel cell is bent in an
accordion-fold, it is less likely to be damaged than the power
generator panel structured in a single flat plate.
Embodiment 4
[0048] FIG. 7 is a schematic cross section showing the display
section 2 of the information electronic device 4 provided with a
fuel cell according to a fourth embodiment of the present invention
and the fuel cell in power supply mode. In the stop mode in which
electric power is not supplied, the power generator of the fuel
cell is substantially in one body with the information electronic
device as shown in FIG. 1 of the first embodiment. When the power
switch is turned on, the power supply mode is detected, the power
generator panel 1 of the fuel cell is slided up beyond the
information electronic device 4 (in vertical direction in FIG. 7)
to thereby obtain a space to supply air to the first surface 1a of
the power generator panel 1, and the fuel begins to be supplied,
and the supply of fuel is started. The fuel tank 3 is incorporated
in the information electronic device 4, and a small pump is used to
supply a fuel to the power generator panel 1 through a flexible
fuel supply pipe. Besides a single flat panel type, the power
generator panel 1 may be structured such that a flat panel consists
of strips which are folded in power supply mode, and the panel
unfolds into a single flat panel when power is supplied. As has
been described, instead of in the through-thickness direction (the
left-right direction in FIG. 7) of the display section 2 of the
information electronic device, the power generator panel 1 extends
in the vertical direction of the display section 2, so that the
information electronic device 4 can maintain the thinness even when
it is made operative.
[0049] In this case, it is conceivable that the power generator
panel is made to extend laterally (in the depth direction in FIG.
7) of the display section 2.
[0050] According to the present invention, an electronic device
with a fuel cell is provided which is so structured as to supply
air from at least two surfaces of the casing for better energy
efficiency.
[0051] It should be further understood by those skilled in the art
that although the foregoing description has been made on
embodiments of the invention, the invention is not limited thereto
and various changes and modifications may be made without departing
from the spirit of the invention and the scope of the appended
claims.
* * * * *