U.S. patent application number 09/416920 was filed with the patent office on 2002-04-18 for interfacing a conditional access circuit to a digital device using input and output stream switching.
Invention is credited to CANDELORE, BRANT L..
Application Number | 20020044656 09/416920 |
Document ID | / |
Family ID | 23651842 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020044656 |
Kind Code |
A1 |
CANDELORE, BRANT L. |
April 18, 2002 |
INTERFACING A CONDITIONAL ACCESS CIRCUIT TO A DIGITAL DEVICE USING
INPUT AND OUTPUT STREAM SWITCHING
Abstract
The present invention is a method and apparatus for interfacing
a host and a conditional access circuit to a digital device. A
switching circuit is coupled to the host and the conditional access
circuit to switch input streams into output streams. The input
streams include a host stream from the host and the output streams
include an interface output stream. An interface circuit is coupled
to the steering circuit and the digital device to transfer the
interface output stream to the digital device.
Inventors: |
CANDELORE, BRANT L.;
(ESCONDIDO, CA) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN LLP
12400 WILSHIRE BOULEVARD
7TH FLOOR
LOS ANGELES
CA
90025
|
Family ID: |
23651842 |
Appl. No.: |
09/416920 |
Filed: |
October 13, 1999 |
Current U.S.
Class: |
380/201 ;
348/E7.061; 380/210; 725/31 |
Current CPC
Class: |
H04N 7/163 20130101;
H04N 21/4367 20130101; H04N 2005/91364 20130101; H04N 21/4181
20130101; C12Q 1/6837 20130101 |
Class at
Publication: |
380/201 ;
380/210; 725/31 |
International
Class: |
H04N 007/167 |
Claims
What is claimed is:
1. An apparatus to interface a conditional access circuit to a
digital device, the apparatus comprising: a switching circuit
coupled to a host and the conditional access circuit to switch
input streams into output streams, the input streams including a
host stream from the host, the output streams including an
interface output stream; and an interface circuit coupled to the
switching circuit and the digital device to transfer the interface
output stream to the digital device.
2. The apparatus of claim 1 wherein the host stream is in one of
scrambled and clear formats.
3. The apparatus of claim 2 wherein the conditional access circuit
includes a de-scrambler and a copy protection circuit, the
de-scrambler receiving a de-scrambler input stream and generating a
de-scrambled stream.
4. The apparatus of claim 3 wherein the output streams further
include a copy stream to the copy protection circuit and the
de-scrambler input stream to the de-scrambler.
5. The apparatus of claim 4 wherein the input streams further
include the de-scrambled stream from the de-scrambler and an
interface input stream from the interface circuit.
6. The apparatus of claim 5 wherein the switching circuit
comprises: a first switching element coupled to the host and the
de-scrambler to provide the interface output stream from an
internal stream and the de-scrambled stream; and a second switching
element coupled to the digital device, the copy protection circuit
and the de-scrambler to provide the copy stream from the
descrambled stream and the interface input stream.
7. The apparatus of claim 6 wherein the internal stream provides
the de-scrambler input stream and wherein the host stream provides
the internal stream.
8. The apparatus of claim 6 further comprising: a third switching
element coupled to the first switching element, the digital device
and the de-scrambler to provide the de-scrambler input stream to
the de-scrambler from the host stream and the interface input
stream.
9. The apparatus of claim 8 further comprising: a fourth switching
element coupled to the first and third switching elements to
provide the internal stream from the host stream and a scrambled
stream; and a scrambler coupled to the fourth switching element and
the de-scrambler to provide the scrambled stream from the
de-scrambled stream.
10. The apparatus of claim 1 wherein the interface circuit provides
a 1394 serial interface.
11. A method to interface a conditional access circuit to a digital
device, the apparatus comprising: switching input streams into
output streams by a switching circuit coupled to a host and the
conditional access circuit, the input streams including a host
stream from the host, the output streams including an interface
output stream; and transferring the interface output stream to the
digital device by an interface circuit.
12. The method of claim 11 wherein the host stream is in one of
scrambled and clear formats.
13. The method of claim 12 wherein the conditional access circuit
includes a de-scrambler and a copy protection circuit, the
de-scrambler receiving a de-scrambler input stream and generating a
de-scrambled stream.
14. The method of claim 13 wherein the output streams further
include a copy stream to the copy protection circuit and the
de-scrambler input stream to the de-scrambler.
15. The method of claim 14 wherein the input streams further
include the de-scrambled stream from the de-scrambler and an
interface input stream from the interface circuit.
16. The method of claim 15 wherein switching comprises: providing
the interface output stream from an internal stream and the
de-scrambled stream by a first switching element; and providing the
copy stream from the de-scrambled stream and the interface input
stream by a second switching element.
17. The method of claim 16 wherein the internal stream provides the
de-scrambler input stream and wherein the host stream provides the
internal stream.
18. The method of claim 16 further comprising: providing the
de-scrambler input stream to the de-scrambler from the host stream
and the interface input stream by a third switching element.
19. The method of claim 18 further comprising: providing the
internal stream from the host stream and a scrambled stream by a
fourth switching element; and providing the scrambled stream from
the de-scrambled stream by a scrambler.
20. The method of claim 11 wherein the interface circuit provides a
1394 serial interface.
21. A system comprising: a host to provide a content; a conditional
access device coupled to the host to provide conditional access to
the content, the condition access device having a conditional
access circuit; a digital device coupled to the conditional access
device to access the content; and a circuit coupled to the host and
the digital device to provide interface between the conditional
access device and the digital device, the circuit comprising: a
switching circuit coupled to the host and the conditional access
circuit to switch input streams into output streams, the input
streams including a host stream from the host, the output streams
including an interface output stream, and an interface circuit
coupled to the switching circuit and the digital device to transfer
the interface output stream to the digital device.
22. The system of claim 21 wherein the host stream is in one of
scrambled and clear formats.
23. The system of claim 22 wherein the conditional access circuit
includes a de-scrambler and a copy protection circuit, the
de-scrambler receiving a de-scrambler input stream and generating a
de-scrambled stream.
24. The system of claim 23 wherein the output streams further
include a copy stream to the copy protection circuit and the
de-scrambler input stream to the de-scrambler.
25. The system of claim 24 wherein the input streams further
include the de-scrambled stream from the de-scrambler and an
interface input stream from the interface circuit.
26. The system of claim 25 wherein the switching circuit comprises:
a first switching element coupled to the host and the de-scrambler
to provide the interface output stream from an internal stream and
the descrambled stream; and a second switching element coupled to
the digital device, the copy protection circuit and the
de-scrambler to provide the copy stream from the descrambled stream
and the interface input stream.
27. The system of claim 26 wherein the internal stream provides the
de-scrambler input stream and wherein the host stream provides the
internal stream.
28. The system of claim 26 wherein the switching circuit further
comprises: a third switching element coupled to the first switching
element, the digital device and the de-scrambler to provide the
de-scrambler input stream to the de-scrambler from the host stream
and the interface input stream.
29. The system of claim 28 wherein the switching circuit further
comprises: a fourth switching element coupled to the first and
third switching elements to provide the internal stream from the
host stream and a scrambled stream; and a scrambler coupled to the
fourth switching element and the de-scrambler to provide the
scrambled stream from the de-scrambled stream.
30. The system of claim 21 wherein the interface circuit provides a
1394 serial interface.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention is related to conditional access
devices. In particular, the present invention is related to
interfacing a conditional access device to a digital device.
[0003] 2. Description of Related Art
[0004] Modern set-top boxes generally have a receiver to receive
program data, or content, from a service provider and generate
multiple transport streams. The content is normally scrambled
before being transmitted to the receiver. The scrambled content is
then de-scrambled by a conditional access (CA) device. Currently,
entitlement management messages (EMM) typically use unique keys or
signatures to deliver a group key or access parameters to CA
devices. An EMM is a message used to deliver privileges (e.g.,
rights, keys) to a CA device. Typically the group are users or
customers who share a particular set of entitlements. The National
Renewable Security System (NRSS) defines two types of CA devices or
modules: an NRSS part A module supporting a smart card form factor,
and an NRSS part B module supporting a PCMCIA form factor.
[0005] The unscrambled content is then transferred or downloaded to
a digital device such as a display device (e.g., digital
television) for program viewing or a recording device (e.g.,
digital video cassette recorder) for program recording. In many
scenarios, multiple digital devices are connected to the
conditional access device for simultaneous activities such as
viewing while recording or viewing at different display
locations.
[0006] A standardized interface between the conditional access
device and the digital device is desirable. However, it is
important to safeguard the content or transport streams from
unauthorized copying by the digital device. In addition, the
interface should be flexible enough to accommodate several usage
options such as store and playback.
[0007] Therefore, there is a need to have an efficient and flexible
technique to interface a conditional access device to a digital
device.
SUMMARY
[0008] The present invention is a method and apparatus for
interfacing a host and a conditional access circuit to a digital
device. A switching circuit is coupled to the host and the
conditional access circuit to switch input streams into output
streams. The input streams include a host stream from the host and
the output streams include an interface output stream. An interface
circuit is coupled to the steering circuit and the digital device
to transfer the interface output stream to the digital device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The features and advantages of the present invention will
become apparent from the following detailed description of the
present invention in which:
[0010] FIG. 1 is a diagram illustrating a system in which one
embodiment of the invention can be practiced.
[0011] FIG. 2 is a diagram illustrating a digital receiver and a
decoder according to one embodiment of the invention.
[0012] FIG. 3 is a diagram illustrating a conditional access system
according to one embodiment of the invention.
[0013] FIG. 4A is a diagram illustrating a switching circuit
according to one embodiment of the invention.
[0014] FIG. 4B is a diagram illustrating another switching circuit
according to one embodiment of the invention.
[0015] FIG. 4C is a diagram illustrating a switching circuit with a
re-scrambler according to one embodiment of the invention.
DESCRIPTION
[0016] The present invention is a method and apparatus to interface
a host and a conditional access circuit to a digital device. A
switching circuit is coupled to the host and the conditional access
circuit to switch input streams into output streams. The input
streams include a host stream from the host. The output streams
include an interface output stream. An interface circuit is coupled
to the switching circuit and the digital device to transfer the
interface output stream to the digital device. The conditional
access circuit includes a de-scrambler and a copy protection
circuit. The de-scrambler receives a de-scrambler input stream and
generates a de-scrambled stream. The output streams further include
a copy stream to the copy protection circuit and the de-scrambler
input stream to the descrambler. The input streams further include
the de-scrambled stream from the de-scrambler and an interface
input stream from the interface circuit.
[0017] In one embodiment, the switching circuit comprises a first
switching element coupled to the host and the de-scrambler to
provide the interface output stream from an internal stream and the
de-scrambled stream; and a second switching element coupled to the
digital device, the copy protection circuit and the de-scrambler to
provide the copy stream from the de-scrambled stream and the
interface input stream.
[0018] The switching and interface circuit provides flexibility in
data routing for input and output streams to support a variety of
platforms, configurations, or environments.
[0019] In the following description, numerous specific details are
set forth in order to provide a thorough understanding of the
present invention. It will be apparent, however, to one of ordinary
skill in the art that the present invention may be practiced
without these specific details. In other instances, well-known
architectures, steps, and techniques have not been shown where
unnecessary for an understanding of the present invention. For
example, specific details are not provided as to whether the method
is implemented in a station as a software routine, hardware
circuit, firmware, or a combination thereof. The term "stream"
refers to a transport stream which is typically in a digital
form.
[0020] FIG. 1 is a diagram illustrating a system 100 in which one
embodiment of the invention can be practiced. The system 100
includes a program data receiver 110, a transmission medium 120, an
audio system 130, a digital video recorder or player 140, a disk
recording unit 150, a display 160, a control unit 170, and a
network CA unit 180. Any of the audio system 130, the digital video
recorder or player 140, the disk recording unit 150, the display
160 and the control unit 170, or any combination thereof may be
referred to as a digital device.
[0021] The program data receiver 110 includes a digital receiver
112 and a decoder 114. The digital receiver 112 receives digital
bitstream or data including program data from one or more service
providers. Such service or content providers may include
terrestrial broadcasters, cable operators, direct broadcast
satellite (DBS) companies, companies providing content for download
via the Internet, book publisher, software companies distributing
software products, or any similar content and/or service provider.
The program data may include system information, entitlement
control messages, entitlement management messages, content, and
other data. System information may include information on program
names, time of broadcast, source, method of retrieving and
decoding, copy management commands that provide digital receivers
and other devices that control how, when, and what program data may
be replayed, retransmitted, copied, and/or recorded. These copy
management commands may also be transmitted along with entitlement
control messages (ECM), which are generally used by the conditional
access unit to regulate access to a particular channel or service.
Entitlement management messages (EMM) may be used to deliver
privileges such as rights and de-scrambling keys. As known, a
decryption or de-scrambling key is generally a code that is
required to restore the scrambled data, and may be a function of
the rights granted. Finally, content in the program data may
include audio and video data, which may be in s scrambled or
encrypted or clear format. In one embodiment, the program data
receiver 110 is a television set where the digital receiver 112 is
a set-top box integrated therein, and the decoder 114 is a Motion
Picture Experts Group (MPEG) decoder.
[0022] The transmission medium 120 operates to transmit control
information and data including program data between the program
data receiver 110 and other components in the system 100. The
transmission medium 120 may include air, fiber optics, electronic
and magnetic media, computer network connection, telephone
connection, and any other communication media.
[0023] The audio system 130 is coupled to the transmission medium
130 to provide audio services. The audio system 130 may include
speakers, an audio player/recorder such as a compact disk player,
or other magneto-optical disc that may be used to play and/or
record audio data. The digital video recorder/player 140 is coupled
to the transmission medium 120 to provide video services. The
digital video recorder/player 140 may be used to record analog or
digital video, audio, and other data transmissions. In one
embodiment, the digital video recorder/player 140 may be used to
replay or record the program data received by the program data
receiver 110 and transmitted over the transmission medium 120.
[0024] The disk recording unit 150 may also be coupled to the
program data receiver 110 and other components via the transmission
medium 120. The disk recording unit 150 may be a personal computer
system, a stand-alone hard disk recording unit, or other disk
recording device capable of recording analog or digital audio,
video and data transmissions, including the program data received
and transmitted by the program data receiver 110.
[0025] The display 160 may include a television display, a monitor
display or other devices capable of processing and displaying video
signals. In one embodiment, the display 160 is a digital television
set. The control unit 170 may also be coupled to the transmission
medium 120 to coordinate and control the operation of some or each
of the components on the system 100, as well as other devices
remotely coupled thereto.
[0026] The network conditional access (CA) unit 180 may also be
coupled to the transmission medium 120. The network CA unit 180
operates to re-scramble program data with content in clear format
such that the system 100 supports the simultaneous transmission of
program data in clear and scrambled format. The network CA unit 180
may be a CA device that operates as a second CA device in a system
embodiment where the program data receiver 110 operates as a master
CA device.
[0027] FIG. 2 is a diagram illustrating a digital receiver 112
according to one embodiment of the invention. The digital receiver
112 includes a central processing unit (CPU) 210, a tuner 220, a
demodulator 230, a conditional access (CA) unit 240, and a
demultiplexer 250.
[0028] The control processing unit 210 performs control functions
for the tuner 220, the CA unit 240 and the demultiplexer 250. The
CPU 210 may determine the frequency in which a channel is broadcast
or otherwise transmitted. The CPU 210 may support a graphical user
interface (GUI), such as electronic programming guide (EPG) to
allow a user to navigate through various channels and program
options to select a desired channel or program for viewing,
listening, recording and the like.
[0029] The tuner 220 selects a frequency of the signal received by
the program data receiver 110 (in FIG. 1) under the control of the
CPU 210. The tuner 220 processes, amplifies, digitizes, and
generates a bitstream to the demodulator 230.
[0030] The demodulator 230 demodulates the bitstream received from
the tuner 220 to provide the program data as originally
transmitted. The type of demodulation performed by the demodulator
230 depends on the type of transmission as well as the modulation
process used in the transmission process. Examples of the
demodulation includes quadrature amplitude modulation (QAM)
demodulation, quadrature phase shift key (QPSK) demodulation, and
vestigial side band (VSB) demodulation. In addition, the
demodulator 230 may perform error correction on the received
bitstream.
[0031] The conditional access unit 240 may be integral or external
to the digital receiver 112. The CA unit 240 provides conditional
access to the program data as provided by the demodulator 230. The
program data is typically scrambled using an access key. The CA
unit 240 may be used in an external or split mode. In the external
mode, the CA unit 240 de-scrambles the program data content and
decrypts the keys externally; e.g., as is the case with the
National Renewable Security System (NRSS) conditional access
modules. In a split conditional access unit, the program data
content is de-scrambled within the digital receiver 112, while the
key decryption is done externally, e.g., via a smart card.
[0032] The demultiplexer 250 receives the de-scrambled or
unscrambled content from the CA unit 240. The demultiplexer 250
separates the system information from the content in the program
data, and according to one embodiment, parses the program data for
packet identifiers that are associated with the system information,
audio information, and video information, and then transmits the
system information to the control processing unit 210 and the audio
and video information to the decoder 114 (in FIG. 1).
[0033] When the CA device 240 is used externally to the digital
receiver 112, the digital receiver 112 is typically referred to as
a host. In the following, a host is used to describe a digital
receiver or any device or system that can provide a transport
stream to the CA device. A digital device is any one of the audio
system 130, the digital video recorder or player 140, the disk
recording unit 150, the display 160 and the control unit 170 (shown
in FIG. 1), or any combination thereof.
[0034] FIG. 3 is a diagram illustrating a conditional access (CA)
device 240 according to one embodiment of the invention. The CA
device 240 includes a switching and interface circuit 310, a CA
circuit 320, a CA processor 330, and a smart card interface
340.
[0035] The switching and interface circuit 310 is coupled to the
host, the CA circuit 320 and the digital device to provide
interface between the CA device 240 and the digital device. The
switching and interface circuit 310 includes a switching circuit
312 and an interface circuit 314. The CA circuit 320 scrambles a
stream and generates a copy-protected stream to the host. The CA
circuit 320 includes a copy protection circuit 322 and a
de-scrambler 324.
[0036] The switching circuit 312 is coupled to the host and the CA
circuit 320 to switch input streams into output streams. The input
streams include a host stream from the host, a de-scrambled stream
from the de-scrambler 324, and an interface input stream from the
interface circuit 314. The output streams include an interface
output stream to the interface circuit 314, a de-scrambler input
stream to the de-scrambler 324, and a copy stream to the
copy-protection circuit 322.
[0037] The interface circuit 314 is coupled to the switching
circuit 310 and a digital device to transfer the interface output
stream from the switching circuit 310 to the digital device and the
interface input stream from the digital device to the switching
circuit 310. The interface circuit 314 convert the interface output
stream into the corresponding interface protocol, and the stream
from the digital device into the proper stream to the switching
circuit 310. In one embodiment, the interface protocol is the 1394
serial interface protocol. The digital device may be any one of the
audio system 130, the digital video recorder or player 140, the
disk recording unit 150, the display 160 and the control unit 170
(shown in FIG. 1), or any combination thereof. It is contemplated
that the digital device has a corresponding interface compatible
with the interface circuit 314, e.g., supporting the same interface
protocol.
[0038] The de-scrambler 324 receives and de-scrambles the
de-scrambler input stream from the switching circuit 310 to
generate the de-scrambled stream. The de-scrambler 324 receives the
control and a de-scrambling key from the CA processor 330.
[0039] The copy protection circuit 322 receives the copy stream
from the switching circuit 312 and generates a copy protected
stream to the host. In general, the host then receives a
de-scrambled and copy-protected stream from the CA device 300.
[0040] The CA processor 330 provides control and coordination of
conditional access operations. The CA processor 330 may also
provides control to the switching circuit 312 to control the
switching or data selection functions. The smart card interface 340
provides interface to the smart card. In one embodiment, the smart
card interface 340 is the PCMCIA card interface.
[0041] The switching circuit 312 provides a number of switching
methods to the input streams to the output streams. Alternative
embodiments exist to provide several data paths for the streams to
be routed or steered within the switching circuit 312.
[0042] FIG. 4A is a diagram illustrating a switching circuit 312A
according to one embodiment of the invention. The switching circuit
312A includes a first switching element 410 and a second switching
element 420.
[0043] The first switching element 410 receives the host stream
from the host and the de-scrambled stream from the de-scrambler 324
(shown in FIG. 3). The host stream may be in a scrambled or clear
format. The first switching element 410 generates an internal
stream, and generates the de-scrambler input stream to the
de-scrambler 324 and the interface output stream to the interface
circuit 314.
[0044] The first switching element 410 includes a connection to
connect the host stream to the internal stream and the de-scrambler
input stream. In other words, the host stream is the internal
stream and also the de-scrambler input stream. The first switching
element 410 further includes a data selector, or multiplexer, 412.
The data selector 412 receives at its inputs the host stream and
the descrambled stream and provides the interface output stream.
The data selector 412 may be controlled by the CA processor 330 (in
FIG. 3).
[0045] The second switching element 420 includes a data selector
422. The data selector 422 receives at its inputs the interface
input stream from the interface circuit 314 (in FIG. 3) and the
de-scrambled stream from the de-scrambler 324 (in FIG. 3), and
generates the copy stream to the copy protection circuit 322 (in
FIG. 3). The data selector 422 may be controlled by the CA
processor 330 (in FIG. 3).
[0046] The first and second switching elements 410 and 420 provide
flexible data routing for the input and output streams. A number of
scenarios exist. For example, the host stream may be in scrambled
format and is routed to the descrambler 324. The de-scrambler 324
de-scrambles the scrambled host stream. The data selector 412 then
selects the de-scrambled host stream to the interface output
stream. The interface output stream is the host stream in the clear
format. The interface circuit 314 then sends the clear host stream
to the digital device such as a digital television for displaying
the original content. In another scenario, the host stream may be
in the clear format and can be delivered directly to the interface
output stream via the data selector 412. The digital device may
provide a return path of a clear stream to the switching element
420 to be sent to the copy protection circuit 322. The copy
protection circuit 322 then provides a copy protected stream to the
host.
[0047] FIG. 4B is a diagram illustrating a switching circuit 312B
according to one embodiment of the invention. The switching circuit
312B includes the first and second switching elements 410 and 420
(in FIG. 4A) and a third switching element 430.
[0048] The third switching element 430 includes a data selector
432. The data selector 432 receives the internal stream from the
first switching element 410 and the interface input stream from the
interface circuit 314 (in FIG. 3), and provides the de-scrambler
input stream to the de-scrambler 324 (in FIG. 3). The third
switching element 430 may be controlled by the CA processor 330 (in
FIG. 3).
[0049] The first, second, and third switching elements 410, 420,
and 430, provide further flexible data routing for the input and
output streams. With the addition of the third switching element
430, the de-scrambler input stream may be taken from the host
stream or from the return stream provided by the digital device.
The return stream from the digital device may be scrambled and is
de-scrambled by the de-scrambler 324.
[0050] FIG. 4C is a diagram illustrating a switching circuit 312C
according to one embodiment of the invention. The switching circuit
312C includes the first, second, and third switching elements 410,
420, and 430 (in FIG. 4B), a fourth switching element 440, and a
scrambler 450.
[0051] The fourth switching element 440 includes a data selector
442. The data selector receives the host stream and a scrambled
stream from the scrambler, and generates the internal stream to the
first switching element 410. The fourth switching element 440 may
be controlled by the CA processor 330 (in FIG. 3).
[0052] The scrambler 450 receives the de-scrambled stream from the
descrambler 324 and provides the scrambled stream to the fourth
switching element 440. The scrambler 450 may act as a re-scrambler
for the return stream from the digital device.
[0053] The first, second, third, and fourth switching elements 410,
420, 430, and 440, and the scrambler 450 provide further
flexibility in data routing for the input and output streams. A
number of scenarios exist. For example, a "store and playback"
scheme can be supported which allows a scrambled content, either
from the broadcast stream from the host or locally scrambled, to be
recorded or played back through the switching and interface
circuit. For example, a scrambled content may be provided by a
digital device via the interface input stream. The scrambled
content is then de-scrambled by the de-scrambler 324 via the
switching element 430. This de-scrambled content is then
re-scrambled by the scrambler 450 and goes through the switching
elements 440 and 410 to the interface circuit 314. The re-scrambled
content is then transferred to the same or different digital device
via the interface circuit 314. At the same time, the de-scrambled
content can be copy protected by the copy protection circuit via
the switching element 420 and sent to the host.
[0054] While this invention has been described with reference to
illustrative embodiments, this description is not intended to be
construed in a limiting sense. Various modifications of the
illustrative embodiments, as well as other embodiments of the
invention, which are apparent to persons skilled in the art to
which the invention pertains are deemed to lie within the spirit
and scope of the invention.
* * * * *