Optical communications – Optical transceiver – Including compensation
Reexamination Certificate
1998-09-22
2004-01-13
Pascal, Leslie (Department: 2633)
Optical communications
Optical transceiver
Including compensation
C398S009000, C398S015000, C398S022000, C398S025000, C398S033000, C398S135000, C398S017000
Reexamination Certificate
active
06678477
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spatial transmission optical transceiver (transmitter/receiver) for transmitting/receiving optical signals through space serving as a medium between terminal devices in a network in which a plurality of terminal devices are connected to one another through a serial bus.
Here, the serial bus is used a high-speed serial bus which is standardized in IEEE (The Institute of Electrical and Electronics Engineers) 1394 (“IEEE Standard for a High Performance Serial Bus”, IEEE Inc., 96.8).
2. Description of the Related Art
A requirement for transmitting a huge mass of data between equipments is now increasingly enhanced in connection with recent enhancement of processing capabilities of computers and increasing requirements for handling a mass of data which are represented by motion pictures.
FIG. 10
is a block diagram showing a network using IEEE1394.
In
FIG. 10
, the respective terminal devices are connected to one another through a feeder-affixed twisted pair line
82
into which a transmission path based on the IEEE1394 standard and a feeder are unified, and each terminal device applies a bias voltage to a twisted pair line. When a feeder-affixed twisted pair line is inserted into or removed from a terminal device, the terminal device concerned detects variation of the bias voltage to detect the insertion/removal of the feeder-affixed twisted pair line and transmits a reset signal to initialize an IEEE1394 network.
FIG. 11
is a block diagram showing the construction of a optical transceiver disclosed in Japanese Laid-open patent Application No. Hei-10-41898 which uses an optical fiber as a part of the transmission path. The optical transceiver is connected to a terminal device through a feeder-affixed twisted pair line based on the IEEE1394 standard, and an optical fiber can be used for a part of the transmission path of the IEEE1394 network.
The operation of the optical transceiver will be described hereunder.
In
FIG. 11
, the optical transceiver used through the optical fiber comprises a bias circuit
91
, a code conversion circuit
92
, a peak hold circuit
93
, a optical transmitter
94
, a optical receiver
95
, a power circuit
96
, an electrical connector
98
to which a feeder-affixed twisted pair line
97
based on the IEEE1394 standard is connected, and an optical connector
910
to which an optical fiber
99
is connected.
The optical transmitter
94
converts an electrical signal from the code conversion circuit
92
to an optical signal, and transmits the optical signal thus converted through the optical connector
910
onto an optical fiber
99
b
. The optical transmitter
94
has a function of converting the optical signal received by the optical connector
910
to an electrical signal, performing waveform shaping and then outputting it to the code conversion circuit
92
and the peak hold circuit
93
.
The feeder-affixed twisted pair line
97
has two twisted pair lines, and signals of two lines exist in the feeder-affixed twisted pair line
97
. The code conversion circuit
92
has a function of converting the signals of two lines to signals of one line so that the signals of two lines can be transmitted through the optical fiber
99
when an optical transmission is outputted, and a function of converting the optical signals of one line thus received to signals of two lines so that the signals can be transmitted on a twisted pair line.
The peak hold circuit
93
has a function of detecting the presence or absence of an optical signal on the basis of the electrical signal which is converted from the optical signal by the optical receiver
95
, and a function of controlling the bias circuit
91
on the basis of the detection result. The bias circuit
91
has a function of applying a bias voltage to each twisted pair line
912
a
and
912
b
of the feeder-affixed twisted pair line
97
connected to the electric connector
98
, and it is controlled on the basis of the output of the peak hold circuit
93
. Specifically, when it receives an optical signal, it applies a bias voltage to the twisted pair line
912
a
and
912
b
, and when it receives no optical signal, it stops the voltage application, whereby a terminal device can detect insertion/removal of a feeder-affixed twisted pair line
912
a
and
912
b
or insertion/removal of an optical fiber
99
a
and
99
b
to initialize the IEEE1394 serial bus.
Further, a communication system based on optical or electrical waves by using space as a medium may be utilized from the viewpoint that rewiring due to movement of terminal devices or arrangement of twisted pair lines (cables) in a wiring process spoils the beauty of the appearance. The radio transmission system based on optical technique is called as “optical spatial transmission system”, and it is described in “FUNDAMENTALS OF OPTOELECTRONICS” p. 26 issued by Keigaku Publication Co., Ltd., for example.
FIG. 12
is a block diagram showing an optical spatial transmission device disclosed in Japanese Laid-open Patent Application No. Hei-7-183849. The construction and operation of the optical spatial transmission device will be briefly described with reference to FIG.
12
.
In the optical spatial transmission device of
FIG. 12
, a transmitter
101
includes an encode circuit
102
for converting an input information signal to a base band code, a driver circuit
103
for driving a optical emission unit
104
on the basis of the base band code, and the optical emission unit
104
for converting an electrical signal from the driver circuit
103
to an optical signal and discharging the optical signal to space. A receiver
105
includes a optical reception unit
106
for receiving the optical signal from a spatial transmission path and converting the received optical signal to an electrical signal, a clock reproducing circuit
107
for reproducing a clock signal from the received optical signal, and a decode circuit
108
for reproducing a base band code from the reproduced clock signal and the electrical signal from the optical receiving unit
106
, and outputting an information signal.
In order to solve the rewiring problem due to motion of terminal devices and the appearance-spoiling problem due to the arrangement of cables in the above-described prior art, it is considered that the optical spatial transmission system is applied to the optical transmission/reception portion of the optical transceiver of FIG.
11
. In this case, when the optical communication path is intercepted in the neighborhood of the optical receiving unit and reflected optical is incident to the optical receiving unit, the optical spatial transmission device receives the reflection signal and thus cannot detect the interception of the communication path. Therefore, erroneous data are delivered to a terminal device, and thus the terminal device operates abnormally.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a spatial transmission optical transceiver which can transmit/receive an optical signal through space serving as a communication medium between terminal devices in a network in which plural terminal devices are connected to one another through a data transmission line based on IEEE1394.
In order to attain the above object, a spatial transmission optical transceiver according to the present invention is characterized by detecting interception of a communication path and insertion/removal of a data transmission line connected to a confronting optical transceiver for spatial transmission.
Particularly, even when the optical transceiver for spatial transmission receives reflected optical due to interception of a communication path in the neighborhood of a optical transceiver, the spatial transmission optical transceiver of the present invention detects the interception of the communication path. Specifically, the spatial transmission optical transceiver according to the present invention includes optical signal detection means for detecting the presence or absence of an optical
Matsuda Jun-ichi
Yamazaki Shuntaro
NEC Corporation
Pascal Leslie
Scully Scott Murphy & Presser
Sedighian M. R.
LandOfFree
Spatial transmission optical transceiver does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Spatial transmission optical transceiver, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spatial transmission optical transceiver will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3265200