Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1999-08-04
2002-12-31
Mullen, Thomas (Department: 2632)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200, C359S199200
Reexamination Certificate
active
06501574
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical multiplex transmission apparatus and an optical multiplex transmission method, which enable each of a plurality of control nodes connected to a common optical multiplex transmission path to have its operation mode changed over to a multiplex communication mode wherein the control node performs multiplex communication through an interface for use on multiplex transmission, that is provided to this control node, and to a sleep mode wherein this interface is kept inoperative. More particularly, the invention concerns an optical multiplex transmission apparatus and an optical multiplex transmission method, which can be simplified by changing over the control node from the sleep mode to the multiplex communication mode without providing a wake-up signal electric wire.
2. Related Art
An optical multiplex transmission apparatus for performing multiplex communication has recently been loaded on a vehicle. This optical multiplex transmission apparatus is constructed by a plurality of control nodes being connected to a common optical multiplex transmission path such as an optical fiber.
Each control node has provided therein a multiplex communication interface for performing multiplexing of data and thereby performing transmission and reception thereof, whereby transmission and reception of data are done between microcontrollers provided in the respective control nodes through the multiplex interface and optical multiplex transmission path.
Also, in order to suppress the power consumption maximally, each control node has a change-over function for changing over the mode thereof to a multiplex communication mode for performing multiplex communication through the multiplex transmission interface and to a sleep mode for causing the multiplex transmission interface to be kept inoperative and thereby causing a decrease in the current consumption.
At an ordinary time, the control node is operated in the sleep mode to thereby suppress useless power consumption. When prescribed starting conditions have been satisfied, the mode of the control node is changed over, by a wake-up signal, to the multiplex communication mode in which the operational condition of the microcontroller is made “on” through the multiplex transmission interface.
FIG. 1
is a block diagram illustrating the construction of a type of conventional optical multiplex transmission apparatus. In the optical multiplex transmission apparatus illustrated in
FIG. 1
, it is arranged that a master node
101
serving as a control node and a plurality of slave nodes
102
a
to
102
n
controlled by this master node
101
are connected in the form of a ring by an optical multiplex transmission path
103
(
103
a
to
103
n
) such as an optical fiber, whereby a multiplex communication signal is transmitted in the direction indicated by the arrows.
It is to be noted that in each node Rx represents the reception of a multiplex communication signal and Tx represents the transmission of a multiplex communication signal. Also, a wake-up signal electric wire
104
for transmitting a wake-up signal from the master node
101
to the slave nodes
102
a
to
102
n
is provided.
As described above, the wake-up signal electric wire
104
is provided separately from the optical multiplex transmission path
103
that is a data transmission line. At the time of activation after turning on a main power source, a given node, for example, a master node
101
, transmits a wake-up signal to all the slave nodes
102
a
to
102
n
through the wake-up signal electric wire
104
. Upon receipt of the wake-up signal, each slave node
102
a
to
102
n
changes over the interface portion from the sleep mode to the multiplex communication mode.
In this way, every one of the slave nodes
102
a
to
102
n
is transferred from the sleep mode to the multiplex communication mode, and then bi-directional communication can be made between each node through the optical multiplex transmission path
103
.
However, in the conventional optical multiplex transmission apparatus, although the slave nodes can be stably activated by using a wake-up signal, the wake-up signal electric wire had to be provided separately from the optical multiplex transmission path that is a data transmission line.
Providing this wake-up signal electric wire is due to the following reason. In the sleep mode, the current consumption is appreciably limited. Therefore, in a case where having used the optical multiplex transmission path, the power source of a light receiving portion must be made “off” in order that the apparatus may be in sleep mode.
For this reason, in order to activate from the sleep mode, as illustrated in
FIG. 2
, separately from optical interfaces (optical IFs)
106
a
,
106
b
of, for example, a light receiving portion, etc., the wake-up signal electric wire, i.e., electric interfaces (electric IFs)
107
a
,
107
b
were provided, whereby the apparatus was activated from the sleep mode by using a wake-up signal which is a kind of electric signal. Therefore, there was the problem that the wire reduction effect resulting from the multiplex communication was impaired. In addition, the wiring or distribution of the wake-up signal electric wire became complex or costly.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an optical multiplex transmission apparatus and optical multiplex transmission method which enable the system to be simplified, and enable each control node to be activated and commence its communication, without providing any wake-up signal electric wire separately from a data transmission line.
To attain the above object, there is provided an optical multiplex transmission apparatus wherein a plurality of control nodes are connected to an optical multiplex transmission path; and each control node performs communication, through a multiplex communication portion for use in multiplex transmission that has been provided therein, with another control node, the each control node comprising: a light receiving portion that operates by having a power source signal supplied thereto and receives an optical signal from the another control node; a mode changing-over portion that alternately changes over the mode of the control node between a multiplex communication mode for performing multiplex communication and a sleep mode in which the multiplex communication portion is kept inoperative every prescribed period of time; and a light reception control portion that has alternately repeated therein a power source supply time length corresponding to the multiplex communication mode during which the power source is supplied and a power source non-supply time length corresponding to the sleep mode during which the power source is not supplied, and that produces a power source supply pulse signal wherein a duty ratio between the power source supply time length and the power source non-supply time length is preset and supplies the power source supply pulse signal to the light receiving portion, whereby when the mode changing-over portion changes over the mode of the control node from the sleep mode to the multiplex communication mode and the light receiving portion has received a light signal, the mode changing-over portion causes the multiplex communication mode to be maintained while the light signal is being received, and the light reception control portion causes the power source to continue to be supplied to the light receiving portion while the light signal is being received.
According to this invention, the multiplex communication mode and sleep mode are alternately repeated every prescribed period of time and the power source supply pulse signal having a preset duty ratio is supplied to the light receiving portion. Therefore, the current consumption that is made during the sleep mode is suppressed to a value that falls within a permissible range. Further, when the mode of the control node has been changed over from the sleep mode to the multiplex communication mod
Nakajima Katsutoshi
Nishiyama Hiroshi
Norizuki Akira
Saito Yoshikazu
Tomita Akiyoshi
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Mullen Thomas
Yazaki -Corporation
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