U.S. patent application number 13/430543 was filed with the patent office on 2012-07-19 for optical network unit transceiver module having direct connect rf pin configuration.
This patent application is currently assigned to FINISAR CORPORATION. Invention is credited to Jinxiang Liu, Tat Ming Teo.
Application Number | 20120183300 13/430543 |
Document ID | / |
Family ID | 40351459 |
Filed Date | 2012-07-19 |
United States Patent
Application |
20120183300 |
Kind Code |
A1 |
Liu; Jinxiang ; et
al. |
July 19, 2012 |
OPTICAL NETWORK UNIT TRANSCEIVER MODULE HAVING DIRECT CONNECT RF
PIN CONFIGURATION
Abstract
Methods for providing a direct connect RF pin configuration for
an ONU transceiver module to connect directly to an external
component. The ONU module communicates with an optical network. The
ONU module further includes an RF interface and a direct connect RF
pin configuration to communicate using RF signals. In one
embodiment, the direct connect RF pin configuration includes two
ground pins and a data pin which are spaced apart and directly
connected to a PCB of the ONU. The opposing ends of the pins are
directly connected to a PCB of an external component, such as an
ONU host box. The pins are thus spaced apart such that they do not
impede each others' function and available for direct connection to
the external component.
Inventors: |
Liu; Jinxiang; (Singapore,
SG) ; Teo; Tat Ming; (Singapore, SG) |
Assignee: |
FINISAR CORPORATION
Sunnyvale
CA
|
Family ID: |
40351459 |
Appl. No.: |
13/430543 |
Filed: |
March 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12188132 |
Aug 7, 2008 |
8145058 |
|
|
13430543 |
|
|
|
|
60955489 |
Aug 13, 2007 |
|
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Current U.S.
Class: |
398/116 |
Current CPC
Class: |
H05K 1/0237 20130101;
H05K 2201/10318 20130101; H05K 1/141 20130101; H05K 1/0219
20130101; H05K 2201/042 20130101 |
Class at
Publication: |
398/116 |
International
Class: |
H04B 10/00 20060101
H04B010/00 |
Claims
1. A method for constructing a direct connection between an optical
network unit module and an external component, the method
comprising: tuning one or more characteristics of at least one
ground pin and at least one data pin to achieve a desired
impedance; securing a first end of the at least one ground pin and
the at least one data pin to an RF interface of an optical network
unit such that the at least one ground pin is spaced apart from the
at least one data pin; disposing a second end of the at least one
ground pin and the at least one data pin through a housing of the
optical network unit wherein the second end of the at least one
ground pin and the at least one data pin extends outwardly and is
available to be directly connected to an external component; and
securing the second end of the at least one ground pin and the at
least one data pin to a printed circuit board (PCB) of the external
component.
2. The method of claim 1, wherein the one or more characteristics
of the at least one ground pin and the at least one data pin
includes size, shape, composition and attachment method.
3. The method of claim 1, wherein tuning one or more
characteristics of the at least one ground pin and the at least one
data pin includes utilizing optimization software.
4. The method of claim 1, wherein tuning one or more
characteristics of the at least one ground pin and the at least one
data pin includes iteratively changing characteristics to achieve a
desired impedance.
5. The method of claim 1, wherein tuning one or more
characteristics of the at least one ground pin and the at least one
data pin includes tuning using simulation software.
6. The method of claim 1, further comprising: determining a desired
limit to back reflection at the RF interface; and tuning one or
more characteristics of the at least one ground pin and the at
least one data pin to achieve the desired limit to back
reflection.
7. The method of claim 1, wherein securing a first end of the at
least one ground pin and the at least one data pin to an RF
interface of an optical network unit and securing the second end of
the at least one ground pin and the at least one data pin to a PCB
of the external component comprises using at least one of
soldering, welding, applying conductive epoxy, applying conductive
adhesive, or using a slip fit connection.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 12/188,132 filed Aug. 7, 2008 which claims the
benefit of U.S. Provisional Patent Application Ser. No. 60/955,489
filed on Aug. 13, 2007, applications which are incorporated herein
by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. The Field of the Invention
[0003] The present invention relates to optical network unit (ONU)
transceiver modules. More particularly, the present invention
relates to ONU transceiver modules having individual pins to couple
an RF interface component of the module to an external component,
such as an optical network unit host box.
[0004] 2. Background
[0005] Passive optical networks (PON) allow a host to communicate
efficiently with a number of users. A PON infrastructure often
includes an optical line termination (OLT) unit on the carrier side
of the network and a pluggable optical network unit (ONU)
transceiver module on the user's side. The OLT is operatively
associated with many ONUs through a passive optical splitter. In
particular, a single line of fibers is often directed from the OLT
to the passive optical splitter. Additional fibers then run from
the passive optical splitter to each of the ONUs. Optical signals
coming from the OLT are split and directed along the additional
fibers to the ONUs. Optical signals from the ONUs are sent directly
from the ONU to the passive optical splitter, which allows the
signal to be passed on to the OLT. In such a configuration, the
bandwidth is shared between the ONUs by allocating various time
slots in which the ONUs transmit to the OLT and other time slots in
which the OLT is transmitting to the ONUs or by selecting different
wavelengths for use by the OLT and the ONU. A group of ONUs may
reside on the same host, such as an ONU host box.
[0006] Recent efforts have been directed toward configuring PONs to
receive/transmit radio frequency (RF) signals, such as media or
broadcast signals used in, but not limited to televisions, radios,
and the like. Accordingly, ONUs have been configured to receive RF
signals sent over the PON, allowing the ONUs to communicate via
optical, electrical and RF signals. However, it would be
advantageous to reduce costs of manufacturing ONUs and, hence,
generate competitive pricing for ONUs.
BRIEF SUMMARY
[0007] These and other limitations are overcome by embodiments of
the invention which relate to systems and methods for optimizing
the conversion of multiple analog signals utilizing one analog to
digital converter as controlled by firmware and/or software
associated with optoelectronic devices.
[0008] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential characteristics of the claimed subject
matter, nor is it intended to be used as an aid in determining the
scope of the claimed subject matter.
[0009] One embodiment of the invention includes an optical network
unit (ONU) transceiver module that includes a housing, a printed
circuit board disposed in the housing, an optical connector
disposed on the printed circuit board and configured to connect to
an optical fiber to access an optical network, a transmit line
including a laser driver coupled to the optical connector and a
laser for transmitting optical signals through the optical fiber,
and a receive line including an optical receiver coupled to the
optical connector and a first post amplifier for converting optical
signals to electrical signals. The ONU module further includes an
RF interface disposed on the printed circuit board and configured
to receive and transmit RF signals to and from the external
component and convert RF signals to electrical signals and vice
versa, and a direct connect RF pin configuration having at least
one ground pin, at least one data pin spaced apart from at least
one data pin, and means for connecting a first end of the at least
one ground pin and the at least one data pin to the RF interface.
The second end of the at least one ground pin and the at least one
data pin extends outwardly through two or more apertures of the
housing such that the second end of each pin is available to be
directly connected to the external component. Means for securing
the direct connect RF pin configuration includes soldering,
welding, conductive epoxy, conductive adhesive, a slip fit
connection, and the like.
[0010] Another embodiment of the invention includes a method for
providing a direct connection between a PCB of an ONU module RF
interface and a PCB of an external component using a direct connect
RF pin configuration. The method includes determining a desired
impedance for at least one ground pin and at least one data pin,
tuning one or more characteristics of the at least one ground pin
and the at least one data pin to achieve the desired impedance,
securing a first end of the at least one ground pin and the at
least one data pin to a PCB of an RF interface of an optical
network unit such that the at least one ground pin is spaced apart
from the at least one data pin, disposing a second end of the at
least one ground pin and the at least one data pin through two or
more apertures of a housing of the optical network unit wherein the
second end of the at least one ground pin and the at least one data
pin extends outwardly and is available to be directly connected to
an external component, and securing the second end of the at least
one ground pin and the at least one data pin to a PCB of the
external component.
[0011] Additional features and advantages of the invention will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by the practice of
the invention. The features and advantages of the invention may be
realized and obtained by means of the instruments and combinations
particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] To further clarify the above and other advantages and
features of the present invention, a more particular description of
the invention will be rendered by reference to specific embodiments
thereof which are illustrated in the appended drawings. It is
appreciated that these drawings depict only typical embodiments of
the invention and are therefore not to be considered limiting of
its scope. The invention will be described and explained with
additional specificity and detail through the use of the
accompanying drawings in which:
[0013] FIG. 1 illustrates a prior art optical network unit (ONU)
having a mini coaxial RF connector which allows for connection to
an external component via a cable;
[0014] FIG. 2A illustrates a prior art ONU having an RF connector
which allows for direct connection to an external component;
[0015] FIG. 2B illustrates the prior art RF connector in further
detail;
[0016] FIG. 3 schematically illustrates an example of an ONU that
may be implemented in the present invention;
[0017] FIG. 4A illustrates an interior view of an optical network
unit showing a direct connect RF pin configuration according to one
example of the present invention;
[0018] FIG. 4B illustrates an ONU having direct connect RF pin
configuration available for direct connection to an external
component.
[0019] FIGS. 5A and 5B illustrate two different examples of
securing the direct connect RF pin configuration according to
aspects of the present invention;
[0020] FIG. 6 is a flow diagram illustrating a method for providing
a direct connection between the PCB of an RF interface to the PCB
of an external component with direct connect RF pin
configuration.
DETAILED DESCRIPTION
[0021] The present invention relates to optical network unit (ONU)
transceiver modules, which allow users access to an optical
communication network. The ONU is positioned on an optical access
line and converts optical data to electrical data. ONUs are
generally configured to be pluggable into a host box printed
circuit board (PCB). In particular, the present invention relates
to systems, methods and devices for connecting an RF interface on
an ONU with an external component (such as a host box PCB) in a
manner which drastically reduces the cost associated with
manufacturing the ONU systems.
[0022] FIG. 1 illustrates a conventional ONU module 10 capable of
connection to a fiber optic cable 12 for the input and output of
optical and/or other electromagnetic signals. ONU transceiver
module has I/0 pins 14 for communicating with an external host via
electrical signals. Additionally, FIG. 1 illustrates that ONU
module 10 uses a subminiature coaxial RF connector 16, such MMCX,
MCX, FME, SMA, SMB, or SMC connector, to connect an RF interface
inside the ONU module 10 with an external component (such as the
PCB of a host box) via a connector cable (not shown).
[0023] FIG. 2A illustrates another prior art ONU module 20 that
connects to a fiber optic cable 12 for input/output of optical
signals and communicates electrically via I/O pins 24. ONU module
20 also includes an RF connector 26 that provides direct connection
between the ONU module 20 and an external component. One example of
this type is shown in further detail in FIG. 2B.
[0024] FIG. 2B illustrates that the connector 26 includes a metal
casing 28 with integral peripheral pin features 30a. In the
illustrated example, the peripheral pin features 30a may be ground
pins. The connector 26 also includes a central pin 30b, which may
be a data pin. The central pin 30b is coupled to a central plastic
portion 32, which may serve to isolate the central pin 30b from the
peripheral pins 30a, thereby preserving the separate function of
each pin type. Accordingly, the connector 26 includes pin features
which are secured together with an intervening structure that
maintains the pins spaced apart. The ends of peripheral pin
features 30a and central pin 30b extend from the top and bottom of
the metal casing 28 and plastic portion 32, respectively, to enable
the RF connector to be connected to the ONU module as well as to an
external component. However, both the RF connector configurations
of FIG. 1 and FIG. 2 add to the cost and complexity involved in
connecting an ONU module RF interface to external components.
[0025] In contrast, the present invention provides systems, methods
and devices for connecting an RF interface on an ONU module with an
external component in a manner which reduces the cost associated
with manufacturing ONU systems. Turning to FIG. 3, a schematic
diagram of one embodiment of an ONU module 100 is illustrated. The
ONU module 100 receives an optical signal from fiber 105 using
receiver 120. The receiver 120 acts as an opto-electric transducer
by transforming the optical signal into an electrical signal. The
receiver 120 provides the resulting electrical signal to a
post-amplifier 130. The post-amplifier 130 amplifies the electrical
signal and provides the amplified signal to an external host 115 as
represented by arrow 170. The external host 115 may be, in one
example, an ONU host box capable of housing and communicating with
multiple ONU modules.
[0026] The ONU module 100 may also receive electrical signals from
the host 115 for transmission onto the fiber 110. Specifically, the
laser driver 135 receives an electrical signal from host 115 as
represented by the arrow 175, and drives the transmitter 125 (e.g.,
a laser or Light Emitting Diode (LED)) to emit optical signals onto
the fiber 110, where optical signals are representative of the
information in the electrical signal provided by the host 115.
Accordingly, the transmitter 125 serves as an electro-optic
transducer. Thus, the receiver 120 and transmitter 125 provide an
optical connection to the optical fibers 105, 110. In one
embodiment, the fibers 105 and 110 may be combined in a single
coaxial optical fiber cable.
[0027] The ONU module 100 includes a control module 150, which may
evaluate operating conditions, such as, but not limited to,
temperature, voltage, and low frequency changes (such as receive
power) from the post-amplifier 130 (as represented by arrow 180)
and/or from the laser driver 135 (as represented by arrow 185).
This allows the control module 150 to optimize the dynamically
varying performance, and additionally detect when there is a loss
of signal. The control module 150 can also control the operation of
post amplifier 130, and/or laser driver 135, and, hence, can
control the operation of ONU module 100. The control module 150 can
also communicate with host 115 using, for example, a two-wire I2C
interface shown as the serial data (SDA) and serial clock (SCL)
lines.
[0028] The control module 150 may have access to a persistent
memory 140, which in one embodiment, is an Electrically Erasable
and Programmable Read Only Memory (EEPROM). The persistent memory
140 and the control module 150 may be packaged together in the same
package or in different packages without restriction. Persistent
memory 140 may also be any other non-volatile memory source.
[0029] The ONU module 100 also includes an RF interface 155 which
is configured to receive and/or transmit video and/or RF signals
from and/or to external host 115 as shown by line 152. The RF
interface also converts RF signals to electrical signals and can
communicate those signals to and from control module 150 as shown
by line 154. The ONU module 100 is thus configured to be able to
communicate via optical, electrical and RF signals. Generally, the
components of the ONU module 100 are connected (e.g., soldered) to
a printed circuit board (not shown).
[0030] Turning to FIG. 4A, the RF interface of the ONU module
includes a direct connect RF pin configuration 402. FIG. 4A
illustrates a portion of a printed circuit board (PCB) 400 of an
ONU module and a portion of an RF interface in particular. In the
embodiment of FIG. 4A, the direct connect RF pin configuration 402
comprises three spaced-apart pins--two ground pins 405a and a
central data pin 405b. The pins 405a, 405b are secured directly to
the PCB 400 of the RF interface using a connection means 415. The
connection means 415 may be made using welding, solder, conductive
adhesive, conductive epoxy, slip fit, and the like. The central
data pin 405b and ground pins 405a are configured to extend
outwardly such that they can be connected directly to the PCB of an
external component (not shown). Furthermore, the direct connection
of the pins 405a, 405b to the PCB 400 of the ONU module serves to
maintain the pins spaced apart so that they do not impede each
other in their respective functions. As such, the RF interface will
be able to communicate directly with the PCB of the external
component.
[0031] The characteristics of the pins for the direct connect RF
pin configuration include size, composition and attachment method
that can be selected to tune the impedance of the RF interface to
about 50 .OMEGA. or about 75 .OMEGA.. Such tuning can be achieved
through iterative adjustments. Tuning may also be achieved via
simulations using software. Adjustments to the characteristics of
the pins can include changing the diameter of the ground pins to be
about 4 mm or using ground pins that are larger in diameter than
the data pin.
[0032] Characteristics of the pins can also be selected to limit
the back reflection of power at the RF interface. Back reflection
is the amount of incident power reflected back at the source
measured in decibels (dB). The characteristics of the pins can be
adjusted so that the back reflection is less than about -16 dB,
less than about -26 dB, less than about -30 dB, or less than about
-40 dB at frequencies at about 1 GHz. Further a buffer may be added
of about 10 dB.
[0033] While a three-pin direct connect RF pin configuration will
be shown and described in FIGS. 4A through 5B, in some embodiment,
only a single ground pin and a single data pin could be used.
Alternatively, more than one ground pin and more than one data pin
could also be used. Further, while the pins are shown as
substantially cylindrical, it will be appreciated that ground pins
and/or data pins may have varying cross sections along the length
thereof. For example, the ends of the pins may be wider than an
intermediate portion of the pin to provide more surface area in
order to make the pins more easily connected to the PCB of either
the ONU module or the external component. Further, the sizes of the
ground pins and data pin could differ. In one embodiment, a fat
ground pin design is used. Finally, the spacing between pins and
alignment of pins may vary depending on design considerations.
[0034] FIG. 4B illustrates an example of a ONU module 450
incorporating the novel direct connect RF pin configuration of FIG.
4A to enable a direct connection to be formed during assembly of an
ONU system between the RF interface of the ONU module 450 and an
external component (not shown). The ONU module 450 includes
connection to a fiber optic cable 452 for the input and output of
optical and/or other electromagnetic signals. ONU module 450 has
I/O pins 454 for communicating with an external host via electrical
signals.
[0035] ONU module 450 also includes an RF interface having a direct
connect RF pin configuration 402 that is directly connected to an
RF interface located on a PCB (not shown) of the ONU module 450
(see FIG. 4A). The housing 456 of the ONU module 450 includes three
apertures 458 sized and placed to allow the individual pins 405a,
405b to be disposed therethrough. When the pins 405a, 405b are
disposed through apertures 458, they extend outwardly so that they
are available for direct connection to an external component (not
shown). Preferably, the apertures do not touch the sides of the
pins. However, in some embodiments, the apertures may touch the
sides of the pin, but it should be noted that the primary source
for maintaining the pins as spaced apart comes from the direct
connection of the pins to the PCB of the ONU module that serves to
maintain the pins spaced apart so that they do not impeded each
other in their respective functions. In one example, means for
directly connecting the direct connect RF pin configuration to the
external component include, but are not limited to, soldering,
welding, conductive adhesive, conductive epoxy, or slip fitting the
exposed ends of the pins 405a, 405b to a PCB of an external
component.
[0036] As will be appreciated, the particular direct connect RF pin
configuration shown in FIGS. 4A and 4B allows for the same benefits
as conventional RF connectors, while drastically reducing the cost
associated with conventional RF connector designs, such as
eliminating plastic and/or a metal casing, removing additional
hardware such as a RF cable, as well as eliminating the need for
more costly locking mechanisms, screw-type mechanisms, and the
like. In one example, it is estimated that the present invention
results in a cost reduction of about 95%.
[0037] As discussed above, the individual pins for the direct
connect RF pin configuration may be numbered, sized, shaped, spaced
apart, and/or aligned in various manners to achieve a particular RF
design configuration.
[0038] FIG. 5A illustrates one embodiment for connecting the direct
connect RF pin configuration of the ONU module to a PCB of an
external component. In this embodiment, the direct connect RF pin
configuration comprises a plurality of pins 502. As mentioned
above, the pins may be one or more ground pins and one or more data
pins. The PCB 504 of the ONU module is directly connected to pins
502 using solder 508. On the other side, the pins 502 are directly
connected to a PCB 506 of an external component using solder 508.
The direction connection of the pins 502 to the PCB 504 of the ONU
module serves to maintain the pins 502 spaced apart so that they do
not impeded each other in their respective functions.
[0039] FIG. 5B illustrates that pins 502 can be connected to the
PCB 506 of an external component using a slip fit connection. For
example, slip fit connection may include a plurality of female
receptacles 510 disposed on PCB 506, each sized and spaced to
receive one of the pins 502. As such, pins 502 are able to make
contact with the conductive female receptacle 510 and may be
further bonded to the female receptacles using solder, adhesive,
epoxy, and the like. FIGS. 5A and 5B are presented only by way of
example and not by way of limitation. As discussed above, other
means for directly connecting the pins 502 to PCB 504 and/or 506
can be utilized. For example, a slip fit connection may be used at
both ends of the pins 502 rather than just on one end, or, other
connections means may be used such as welding, conductive epoxy,
conductive adhesive, and the like.
[0040] FIG. 6 illustrates a method for securing an ONU module and
an external component using the novel direct connect RF pin
configurations of the present invention. In at least one example, a
method includes determining a desired impedance or range of
impedance (600). The method may also include selecting the
characteristics of one or more of the pins to limit the back
reflection at the interface (605) and then tuning the
characteristics of the pins including size, shape, composition and
attachment method of one or more of the pins to achieve the desired
impedance (610) and/or back reflection (615). In one example tuning
the characteristics of one or more of the pins includes utilizing
optimization software. In other cases, the characteristics may be
selected and analyzed and then iteratively changed to achieve the
desired impedance and/or back reflection range. In one embodiment,
the characteristics of the pins may be selected based on the
configuration of the PCB of the external component and whether the
external component utilizes a particular PCB connection, such as a
slip fit connection having a particular size, shape or spacing.
[0041] The method may also include connecting one end of a pin
directly to the PCB of an ONU module RF interface 620 and then
connecting the second end of the pin directly to the PCB of the
external component 625. In particular, the connection to the RF
interface and to the external component includes the pins being
separated from each other while directly securing the pins to the
PCB of the RF interface and to the PCB of the external component,
such as by welding, soldering, conductive epoxy, conductive
adhesive, slip fit connection, and the like. The process may be
performed as many times as desired. Accordingly, the method
provides that an RF interface can be directly connected to an
external component using a direct connect RF pin configuration.
Further, the direct connections at the PCB boards maintain the pins
as spaced apart so that no additional intervening structure is
required along the length of the pins to keep the pins spaced
apart. Thus, the pins are able to keep spaced apart so as to not
impede each others functions, while the air between the pins
provides sufficient insulatory function.
[0042] Embodiments of the invention have referred to optical
network unit transceiver modules. However, those of skill in the
art will appreciate that the concepts taught herein with regard to
novel direct connect RF pin configurations may be applied to any
other opto-electronic module or device. Furthermore, embodiments of
opto-electronic modules described herein have been described as
including both hardware and/or software components.
[0043] Embodiments may also include physical computer-readable
media and/or intangible computer-readable media for carrying or
having computer-executable instructions, data structures, and/or
data signals stored thereon. Such physical computer-readable media
and/or intangible computer-readable media can be any available
media that can be accessed by a general purpose or special purpose
computer. By way of example, and not limitation, such physical
computer-readable media can include RAM, ROM, EEPROM, optical
storage devices, magnetic storage devices, semiconductor storage
media, solid-state storage media, or any other physical medium
which can be used to store desired data in the form of
computer-executable instructions, data structures and/or data
signals, and which can be accessed by a processor. Within the
opto-electronic modules, intangible computer-readable media can
include electromagnetic means for conveying a data signal from one
part of the module to another, or even exterior of the module, such
as through circuitry residing in the module.
[0044] When information is transferred or provided over a network
or another communications connection (either hardwired, wireless,
or a combination of hardwired or wireless) to a host or other
external component, hardwired devices for sending and receiving
computer-executable instructions, data structures, and/or data
signals (e.g., wires, cables, optical fibers, electronic circuitry,
chemical, and the like) should properly be viewed as physical
computer-readable mediums while wireless carriers or wireless
mediums for sending and/or receiving computer-executable
instructions, data structures, and/or data signals (e.g., radio
communications, satellite communications, infrared communications,
and the like) should properly be viewed as intangible
computer-readable mediums. Combinations of the above should also be
included within the scope of computer-readable media.
[0045] Computer-executable instructions include, for example,
instructions, data, and/or data signals which cause the
opto-electronic module to perform a certain function or group of
functions. Although not required, aspects of the invention have
been described herein in the general context of computer-executable
instructions, such as program modules, being executed by a
processor, in network environments and/or non-network environments.
Generally, program modules include routines, programs, objects,
components, and content structures that perform particular tasks or
implement particular abstract content types. Computer-executable
instructions, associated content structures, and program modules
represent examples of program code for executing aspects of the
methods disclosed herein.
[0046] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes which come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
* * * * *