U.S. patent application number 11/594115 was filed with the patent office on 2007-05-24 for fan system and seriate starting module and delayed starting unit thereof.
This patent application is currently assigned to DELTA ELECTRONICS, INC.. Invention is credited to Chien-Hua Chen, Wen-Shi Huang, Chia-Pin Wei.
Application Number | 20070116577 11/594115 |
Document ID | / |
Family ID | 38053714 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070116577 |
Kind Code |
A1 |
Chen; Chien-Hua ; et
al. |
May 24, 2007 |
Fan system and seriate starting module and delayed starting unit
thereof
Abstract
A fan system for receiving an input voltage from exterior
includes a first fan module, a second fan module and a seriate
starting module. The seriate starting module is electrically
connected with the first fan module and the second fan module. The
seriate starting module receives the input voltage and starts the
first fan module according to the input voltage, and starts the
second fan module according to the input voltage after the first
fan module is started for a predetermined time.
Inventors: |
Chen; Chien-Hua; (Taoyuan
Hsien, TW) ; Wei; Chia-Pin; (Taoyuan Hsien, TW)
; Huang; Wen-Shi; (Taoyuan Hsien, TW) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
DELTA ELECTRONICS, INC.
|
Family ID: |
38053714 |
Appl. No.: |
11/594115 |
Filed: |
November 8, 2006 |
Current U.S.
Class: |
417/7 ;
417/12 |
Current CPC
Class: |
Y02B 30/70 20130101;
F05D 2260/85 20130101; F04D 27/008 20130101; F04D 27/004
20130101 |
Class at
Publication: |
417/007 ;
417/012 |
International
Class: |
F04B 41/06 20060101
F04B041/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2005 |
TW |
094140585 |
Claims
1. A fan system for receiving an input voltage from exterior, the
fan system comprising: a first fan module; a second fan module; and
a seriate starting module electrically connected with the first fan
module and the second fan module for receiving the input voltage,
starting the first fan module according to the input voltage, and
starting the second fan module according to the input voltage after
the first fan module is started for a predetermined time.
2. The fan system according to claim 1, wherein the seriate
starting module comprises: a starting unit electrically connected
with the first fan module for receiving the input voltage and
starting the first fan module according to the input voltage; and a
delayed starting unit electrically connected with the second fan
module for receiving the input voltage and starting the second fan
module according to the input voltage after the first fan module is
started for the predetermined time.
3. The fan system according to claim 2, wherein the delayed
starting unit comprises: a starting circuit having a first switch
element and a second switch element, wherein the first switch
element receives the input voltage, and the second switch element
is electrically connected with the first switch element to control
the first switch element to start the second fan module; and a
delaying circuit electrically connected with the first switch
element and the second switch element for receiving the input
voltage, and controlling the first switch element and the second
switch element to start the second fan module after the first fan
module is started for the predetermined time.
4. The fan system according to claim 3, wherein the starting
circuit further has at least one diode, and the diode has a first
terminal for receiving the input voltage and a second terminal
electrically connected with the first switch element.
5. The fan system according to claim 4, wherein: each of the first
switch element and the second switch element is a transistor; the
first switch element has a source electrically connected with the
second terminal of the diode, and a drain electrically connected
with the second fan module; and the second switch element has a
gate electrically connected with the delaying circuit, and a drain
electrically connected with the second terminal of the diode and a
gate of the first switch element.
6. The fan system according to claim 5, wherein the first switch
element is a PMOS transistor and the second switch element is an
NMOS transistor.
7. The fan system according to claim 3, wherein the delaying
circuit comprises: a third switch element having one terminal for
receiving the input voltage; a fourth switch element electrically
connected with the third switch element; a first resistor having a
second terminal and a first terminal electrically connected with
the fourth switch element; a capacitor having a first terminal and
a second terminal, wherein the first terminal of the capacitor is
electrically connected with the second terminal of the first
resistor, the second terminal of the capacitor is grounded, and the
first terminal of the capacitor generates a control signal when the
fourth switch element turns on; and a comparator having a first
input terminal for receiving the control signal, a second input
terminal for receiving a reference signal, and an output terminal
electrically connected with the second switch element for
controlling the second switch element.
8. The fan system according to claim 7, wherein the delaying
circuit further comprises a fifth switch element electrically
connected with the first terminal of the capacitor, and a sixth
switch element electrically connected with the fifth switch
element.
9. The fan system according to claim 8, wherein the delaying
circuit further comprises: a second resistor having a second
terminal and a first terminal receiving the input voltage; a third
resistor having a first terminal electrically connected with the
second terminal of the second resistor, and a second terminal
grounded; and a fourth resistor having a first terminal
electrically connected with the sixth switch element, and a second
terminal electrically connected with the starting unit.
10. The fan system according to claim 8, wherein the third switch
element, the fourth switch element, the fifth switch element, and
the sixth switch element are all transistors.
11. The fan system according to claim 8, wherein the fifth switch
element and the sixth switch element are electrically connected
with the starting unit.
12. The fan system according to claim 11, wherein the starting unit
comprises another capacitor electrically connected with the fifth
switch element.
13. The fan system according to claim 7, wherein the predetermined
time is determined according to a charging time of the first
resistor and the capacitor.
14. The fan system according to claim 7, wherein the first input
terminal is a noninverting input terminal, and the second input
terminal is an inverting input terminal.
15. The fan system according to claim 7, wherein the first resistor
is a variable resistor.
16. The fan system according to claim 1, wherein each of the first
fan module and the second fan module comprises at least one
fan.
17. A method of resetting a delaying circuit, wherein the delaying
circuit is coupled with an input voltage from exterior and has a
capacitor and a switch element, and the switch element receives the
input voltage and is electrically connected with the capacitor and
grounded, the method comprising the steps of: separating the
delaying circuit from the input voltage; turning on the switch
element; and forming a discharge path from the capacitor to the
switch element so as to perform a discharging operation.
18. The method according to claim 17, wherein the switch element
turns on by a turn-on voltage provided by an additional
capacitor.
19. The method according to claim 18, wherein the switch element is
a transistor.
20. The method according to claim 17, wherein the switch element
has a base for receiving the input voltage and electrically
connected with the additional capacitor, a collector electrically
connected with the capacitor, and an emitter grounded.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This Non-provisional application claims priority under 35
U.S.C. .sctn.119(a) on Patent Application No(s). 094140585 filed in
Taiwan, Republic of China on Nov. 18, 2005, the entire contents of
which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The invention relates to a fan system and a seriate starting
module and a delayed starting unit thereof, and, in particular, to
a fan system having a plurality of fan modules, and a seriate
starting module and a delayed starting unit of the fan system.
[0004] 2. Related Art
[0005] Generally speaking, a large electronic system is always
equipped with a fan system to ensure that the electronic system can
be kept at the normal working temperature such that the electronic
system can operate normally.
[0006] FIG. 1 is a schematic illustration showing a conventional
fan system 1 disposed in an electronic system (not shown). The fan
system 1 receives an input voltage V.sub.in from exterior to serve
as an operation voltage. The fan system 1 mainly has a starting
module 11 and a plurality of fan modules 12a to 12n. After the
starting module 11 receives the input voltage V.sub.in, the fan
modules 12a to 12n are started simultaneously to dissipate the
heat. However, when the fan modules 12a to 12n are started
simultaneously, an extremely large start-up current and inrush
current are generated at the moment of starting. Thus, the
electronic system or the fan system 1 may crash or have
unpredictable malfunction, or even the electronic system or the fan
system 1 may be damaged.
[0007] As shown in FIG. 2, another conventional fan system 1' has a
plurality of starting modules 11a to 11n corresponding to the fan
modules 12a to 12n so as to start the fan modules 12a to 12n,
respectively.
[0008] In view of the above-mentioned problems, the prior art
adopts an analog starting control chip for starting the fan modules
12a to 12n in sequential, or a software module to control the
starting sequence of the fan modules 12a to 12n. Thus, the prior
art provides a protection mechanism for respectively starting the
fan modules 12a to 12n at different time instants so as to avoid
the malfunction caused when the fan modules 12a to 12n are
simultaneously started. However, the analog starting control chip
has a high price, and the software module has a complicated
architecture. Thus, the overall manufacturing cost of the
conventional fan system 1 is too high. In addition, the analog
starting control chip only can delay the starting time of each of
the fan modules 12a to 12n and cannot provide the function of
soft-start.
[0009] Thus, it is an important subject of the invention to provide
a fan system and a seriate starting module and a delayed starting
unit thereof to overcome the above-mentioned problems.
SUMMARY OF THE INVENTION
[0010] In view of the foregoing, the invention is to provide a fan
system and a seriate starting module and a delayed starting unit
thereof for starting a plurality of fan modules at different time
instants in a seriate manner so as to avoid the malfunction caused
when the fan modules are started simultaneously.
[0011] In addition, the invention is also to provide a fan system
and a seriate starting module and a delayed starting unit thereof
having the resetting effect to discharge the residual charges in
the fan system and thus avoid the malfunction.
[0012] To achieve the above, a fan system of the invention is for
receiving an input voltage from exterior. The fan system includes a
first fan module, a second fan module and a seriate starting
module. The seriate starting module, which is electrically
connected with the first fan module and the second fan module,
receives the input voltage, starts the first fan module according
to the input voltage, and starts the second fan module according to
the input voltage after the first fan module is started for a
predetermined time.
[0013] Furthermore, the invention also discloses a method of
resetting a delaying circuit, which is coupled with an input
voltage from exterior and has a capacitor and a switch element. The
switch element receives the input voltage and is electrically
connected with the capacitor and grounded. The method includes the
steps of: separating the delaying circuit from the input voltage,
turning on the switch element, and forming a discharge path from
the capacitor to the switch element so as to perform a discharging
operation.
[0014] As mentioned above, the fan system and the seriate starting
module and the delayed starting unit thereof according to the
invention can sequentially start a plurality of fan modules at
different time instants so as to avoid the malfunction caused by
the extremely large start-up current and inrush current, which are
generated by instantaneously starting the fan modules. The fan
modules are started in a time-sharing manner to ensure that the fan
system can operate normally, prevent the electronic system and the
fan system from being damaged, and replace the analog starting
control chip to reduce the overall manufacturing cost. In addition,
the invention further possesses the reset function of discharging
the charges remained in the fan system so as to prevent the
malfunction from occurring.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The invention will become more fully understood from the
detailed description given herein below illustration only, and thus
is not limitative of the present invention, and wherein:
[0016] FIG. 1 is a schematic illustration showing a conventional
fan system;
[0017] FIG. 2 is a schematic illustration showing another
conventional fan system;
[0018] FIG. 3 is a schematic illustration showing a fan system
according to a preferred embodiment of the invention; and
[0019] FIG. 4 is a circuit diagram showing a fan system according
to the preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention will be apparent from the following
detailed description, which proceeds with reference to the
accompanying drawings, wherein the same references relate to the
same elements.
[0021] FIG. 3 is a schematic illustration showing a fan system 2
according to a preferred embodiment of the invention. As shown in
FIG. 3, the fan system 2 may be applied to an electronic system
(not shown) in order to dissipate heat. The fan system 2 receives
an input voltage 91 from exterior to serve as an operation voltage.
The input voltage 91 may be supplied from the electronic system.
The fan system 2 includes a first fan module 21, a second fan
module 22 and a seriate starting module 23. Each of the first fan
module 21 and the second fan module 22 has a fan. Of course, the
user may dispose a plurality of fans in each of the first fan
module 21 and the second fan module 22 according to the heat
dissipating requirement so as to enhance the heat dissipating
effect.
[0022] The seriate starting module 23 includes a starting unit 231
and a delayed starting unit 232. The starting unit 231 electrically
connected with the first fan module 21 receives the input voltage
91 and starts the first fan module 21 according to the input
voltage 91. The delayed starting unit 232 includes a starting
circuit 233 and a delaying circuit 234. The starting circuit 233,
which is electrically connected between the second fan module 22
and the delaying circuit 234, receives the input voltage 91. The
delaying circuit 234 controls the starting circuit 233 to start the
second fan module 22 according to the input voltage 91 after the
first fan module 21 is started for a predetermined time.
[0023] Then, the fan system 2 of this embodiment starts the second
fan module 22 after the first fan module 21 is started for the
predetermined time, such that the first fan module 21 and the
second fan module 22 can be started at different time instants.
Thus, it is possible to avoid the malfunction caused by the
extremely large start-up current and inrush current, which are
generated when the first fan module 21 and the second fan module 22
are started simultaneously.
[0024] In addition, FIG. 4 is a circuit diagram showing a fan
system according to the preferred embodiment of the invention.
Referring to FIG. 4, the delayed starting unit 232 includes a
starting circuit 233 and a delaying circuit 234. The starting
circuit 233 has a plurality of diodes D.sub.1 to D.sub.4, a
plurality of resistors R.sub.1 and R.sub.2, a first switch element
Q.sub.1, a second switch element Q.sub.2, a plurality of capacitors
C.sub.1 and C.sub.5. The second switch element Q.sub.2 electrically
connected with the first switch element Q.sub.1 through the diode
D.sub.3 controls the first switch element Q.sub.1. In addition, the
delaying circuit 234 is electrically connected with the first
switch element Q.sub.1 through the diodes D.sub.1, D.sub.2 and is
further electrically connected with the second switch element
Q.sub.2 through the resistor R.sub.9. To be noted, the dispositions
of the diodes D.sub.1, D.sub.2 and the resistor R.sub.9 are used to
make the starting circuit 233 more stable, and are omissible.
[0025] Each of the first switch element Q.sub.1 and the second
switch element Q.sub.2 may be a transistor or any other electronic
element with the switch function. In this embodiment, the first
switch element Q.sub.1 is a PMOS transistor, and the second switch
element Q.sub.2 is an NMOS transistor. In addition, the diodes
D.sub.1 and D.sub.2 are connected in parallel. Each of the diodes
D.sub.1 and D.sub.2 has a first terminal for receiving the input
voltage 91. In this embodiment, each of the diodes D.sub.1 and
D.sub.2 may be a Schottky diode for avoiding the reverse current.
One terminal of the resistor R.sub.1 is electrically connected with
a second terminal of each of the diodes D.sub.1 and D.sub.2.
[0026] A source S of the first switch element Q.sub.1 is
electrically connected with the second terminals of the diodes
D.sub.1 and D.sub.2 to receive the input voltage 91. A drain D of
the first switch element Q.sub.1 is electrically connected with the
second fan module 22 and is used to start the second fan module 22.
A drain D of the second switch element Q.sub.2 is electrically
connected with the second terminals of the diodes D.sub.1 and
D.sub.2 through the resistor R.sub.1. The drain D of the second
switch element Q.sub.2 is further electrically connected with a
gate G of the first switch element Q.sub.1 through the diode
D.sub.3. A gate G of the second switch element Q.sub.2 is
electrically connected with the delaying circuit 234 through the
resistor R.sub.9.
[0027] A first terminal of the diode D.sub.3 is electrically
connected with the drain D of the second switch element Q.sub.2. A
second terminal of the diode D.sub.3 is electrically connected with
the gate G of the first switch element Q.sub.1. A first terminal of
the diode D.sub.4 is electrically connected with the source S of
the first switch element Q.sub.1. A second terminal of the diode
D.sub.4 is electrically connected with the second terminal of the
diode D.sub.3. A first terminal of the capacitor C.sub.1 is
electrically connected with the source S of the first switch
element Q.sub.1, and a second terminal of the capacitor C.sub.1 is
electrically connected with a first terminal of the resistor
R.sub.2. A second terminal of the resistor R.sub.2 is grounded.
[0028] The delaying circuit 234 includes a third switch element
Q.sub.3, a fourth switch element Q.sub.4, a fifth switch element
Q.sub.5, a sixth switch element Q.sub.6, a comparator U.sub.1, a
plurality of resistors R.sub.3 to R.sub.8 and R.sub.12 to R.sub.14,
at least one capacitor C.sub.2 and at least one diode D.sub.5. Each
of the third switch element Q.sub.3, the fourth switch element
Q.sub.4, the fifth switch element Q.sub.5 and the sixth switch
element Q.sub.6 may be a transistor or any other electronic element
with the switch function. In this embodiment, each of the third
switch element Q.sub.3, the fifth switch element Q.sub.5 and the
sixth switch element Q.sub.6 is an NPN transistor, and the fourth
switch element Q.sub.4 is a PNP transistor.
[0029] A base B of the third switch element Q.sub.3 electrically
connected with a first terminal of the resistor R.sub.3 receives
the input voltage 91. A collector C of the third switch element
Q.sub.3 is electrically connected with the diodes D.sub.1 and
D.sub.2 through a resistor R.sub.5. An emitter E of the third
switch element Q.sub.3 and a resistor R.sub.4 are grounded.
[0030] A base B of the fourth switch element Q.sub.4 is
electrically connected with the collector C of the third switch
element Q.sub.3. An emitter E of the fourth switch element Q.sub.4
is connected with an external power VCC.
[0031] The resistor R.sub.6 has a first terminal, which is
electrically connected with a collector C of the fourth switch
element Q.sub.4, and a second terminal.
[0032] The capacitor C.sub.2 has a first terminal, which is
electrically connected with the second terminal of the resistor
R.sub.6 through the diode D.sub.5, and a second terminal grounded.
In addition, the capacitor C.sub.2 starts to charge and generate a
control signal V.sub.1 at the first terminal of the capacitor
C.sub.2 when the fourth switch element Q.sub.4 turns on.
[0033] The comparator U.sub.1 has a first input terminal
input.sub.1, a second input terminal input.sub.2 and an output
terminal output. In this embodiment, the first input terminal
input.sub.1 is a noninverting input terminal and the second input
terminal input.sub.2 is an inverting input terminal. The first
input terminal input.sub.1 is electrically connected with the
second terminal of the resistor R.sub.6. The second input terminal
input.sub.2 is electrically connected with the resistors R.sub.7
and R.sub.8, and the resistors R.sub.7 and R.sub.8 form a
voltage-dividing circuit and provide a reference signal V.sub.ref
to the second input terminal input.sub.2. The output terminal
output, which is electrically connected with the gate of the second
switch element Q.sub.2 through the resistor R.sub.9, controls the
second switch element Q.sub.2.
[0034] A collector C of the fifth switch element Q.sub.5 is
electrically connected with the first terminal of the capacitor
C.sub.2. An emitter E of the fifth switch element Q.sub.5 is
grounded. A collector C of the sixth switch element Q.sub.6 is
electrically connected with a base B of the fifth switch element
Q.sub.5. A base B of the sixth switch element Q.sub.6 is
electrically connected with the input voltage 91 through the
resistor R.sub.12, and an emitter E of the sixth switch element
Q.sub.6 is grounded.
[0035] A first terminal of the resistor R.sub.12 receives the input
voltage 91. A second terminal of the resistor R.sub.12 is
electrically connected with a first terminal of the resistor
R.sub.13. A second terminal of the resistor R.sub.13 is grounded.
Both of the resistors R.sub.12 and R.sub.13 form a voltage-dividing
circuit. The base B of the sixth switch element Q.sub.6, which is
electrically connected with the second terminal of the resistor
R.sub.12, receives the divided input voltage. A first terminal of
the resistor R.sub.14 is electrically connected with the collector
C of the sixth switch element Q.sub.6. A second terminal of the
resistor R.sub.14 is electrically connected with the starting unit
231.
[0036] The starting unit 231 mainly includes a plurality of diodes
D.sub.6 to D.sub.9, a plurality of resistors R.sub.10 and R.sub.11,
two switch elements Q.sub.7 and Q.sub.8 and a plurality of
capacitors C.sub.3 and C.sub.4. The diodes D.sub.6 to D.sub.9, the
resistors R.sub.10 and R.sub.11, the switch elements Q.sub.7 and
Q.sub.8 and the capacitor C.sub.3 have the same constructions and
functions as those of the diodes D.sub.1 to D.sub.4, the resistors
R.sub.1 and R.sub.2, the switch elements Q.sub.1 and Q.sub.2 and
the capacitor C.sub.1, so the detailed descriptions thereof will be
omitted. In addition, the capacitor C.sub.4 is electrically
connected with the base B of the fifth switch element Q.sub.5 and
the collector C of the sixth switch element Q.sub.6 through the
resistor R.sub.14.
[0037] The operation principle of the fan system 2 will be
described in the following. First, after the seriate starting
module 23 receives the input voltage 91 at a first time, the
starting unit 231 and the delayed starting unit 232 simultaneously
receive the input voltage 91 as the operation voltage.
[0038] The diodes D.sub.6 and D.sub.7 of the starting unit 231
receive the input voltage 91 such that the switch element Q.sub.8
turns on and the capacitor C.sub.3 starts to charge until the
voltage value of the capacitor C.sub.3 reaches the turn-on voltage
of the switch element Q.sub.7. When the switch element Q.sub.7
turns on, the first fan module 21 starts to work. In this
embodiment, the charging circuit of the capacitor C.sub.3 and the
resistor R.sub.11 enables the current flowing through the first fan
module 21 to increase at a slow rate such that the effect of soft
starting can be achieved.
[0039] The delaying circuit 234 receives the input voltage 91, the
third switch element Q.sub.3 and the fourth switch element Q.sub.4
turn on, and the capacitor C.sub.2 starts to charge to generate the
control signal V.sub.1. After the predetermined time, the voltage
value of the control signal V.sub.1 is larger than the voltage
value of the reference signal V.sub.ref, and the output terminal
output outputs a positive voltage value to the gate of the second
switch element Q.sub.2 to control the second switch element Q.sub.2
of the starting circuit 233 to turn on. To be noted, the
predetermined time is determined according to the charging time of
the capacitor C.sub.2 and the resistor R.sub.6. The user can select
the different capacitor C.sub.2 and resistor R.sub.6 according to
the to-be-delayed time so as to adjust the predetermined time.
Alternatively, when the resistor R.sub.6 is a variable resistor,
adjusting the resistance of the resistor R.sub.6 can adjust the
predetermined time.
[0040] After the second switch element Q.sub.2 turns on, the
capacitor C.sub.1 starts to charge. When the voltage value of the
capacitor C.sub.1 reaches the turn-on voltage of the first switch
element Q.sub.1, the first switch element Q.sub.1 turns on to start
the second fan module 22 in a soft-starting manner.
[0041] In addition, the fan system 2 of this embodiment further has
the reset function, and the reset method is described in the
following. After the seriate starting module 23 receives the input
voltage 91, the switch elements Q.sub.7 and Q.sub.8 turn on, the
sixth switch element Q.sub.6 of the delaying circuit 234 turns on
according to the voltage-dividing operation of the resistors
R.sub.12 and R.sub.13, and the capacitor C.sub.4 starts to charge.
At this time, the potential of the base B of the fifth switch
element Q.sub.5 is about zero, which means that the fifth switch
element Q.sub.5 is off. When the user removes the fan system 2 from
the electronic system, that is, when the sending of the input
voltage 91 is stopped, the capacitor C.sub.4 starts to discharge,
and the voltage drop generated by the resistor R.sub.14 serves as a
tum-on voltage to turn on the fifth switch element Q.sub.5. At this
time, the capacitor C.sub.2 can form a discharge path through the
fifth switch element Q.sub.5 so as to discharge the charges stored
in the capacitor C.sub.2 and thus achieve the reset effect. Thus,
the malfunction can be avoided when the user inserts the fan system
2 back to the electronic system at the next time. Consequently, the
fan system 2 of this embodiment starts the first fan module 21 and
the second fan module 22 at different time instants using the
seriate starting module 23 so as to achieve the effect of seriate
starting and resetting. In addition, although only two fan modules
are illustrated in FIG. 4, the number of fan modules can be
adjusted according to the user's requirement.
[0042] In summary, the fan system and the seriate starting module
and the delayed starting unit thereof according to the invention
can sequentially start a plurality of fan modules at different time
instants so as to avoid the malfunction caused by the extremely
large start-up current and inrush current, which are generated by
instantaneously starting the fan modules. The fan modules are
started in a time-sharing manner to ensure that the fan system can
operate normally, prevent the electronic system and the fan system
from being damaged, and replace the analog starting control chip to
reduce the overall manufacturing cost. In addition, the invention
further possesses the reset function of discharging the charges
remained in the fan system so as to prevent the malfunction from
occurring.
[0043] Although the invention has been described with reference to
specific embodiments, this description is not meant to be construed
in a limiting sense. Various modifications of the disclosed
embodiments, as well as alternative embodiments, will be apparent
to persons skilled in the art. It is, therefore, contemplated that
the appended claims will cover all modifications that fall within
the true scope of the invention.
* * * * *