Single-fiber bidirectional controller area network bus

Patent metadata

Field	Value
Publication number	US-10615876-B2
Application number	US-201916355712-A
Country	US
Kind code	B2
Filing date	Mar 16, 2019
Priority date	Apr 18, 2017
Publication date	Apr 7, 2020
Grant date	Apr 7, 2020

Abstract

A controller area network (CAN) comprising a plurality of CAN nodes that communicate via a CAN bus that comprises a fiber optical network. The fiber optical network uses a single fiber and a single wavelength for transmit and receive, and comprises a passive reflective optical star. The reflective optical star comprises an optical mixing rod having a mirror at one end. The other end of the reflective optical star is optically coupled to the transmitters and receivers of a plurality of optical-electrical media converters by way of respective high-isolation optical Y-couplers. Each CAN node produces electrical signals (in accordance with the CAN message-based protocol) which are converted into optical pulses that are broadcast to the fiber optical network. Those optical pulses are then reflected back to all CAN nodes by the reflective optical star.

First claim

The invention claimed is:

1. A data communications system comprising:
a plurality of controller area network nodes which operate electrically;
a plurality of signal converters electrically coupled to respective controller area network nodes of the plurality of controller area network nodes, each signal converter comprising electrical circuitry that converts differential signals to digital signals and vice versa;
a plurality of transmit optical subassemblies electrically coupled to respective signal converters of the plurality of signal converters, each transmit optical subassembly comprising a respective transmitter that converts digital signals from a respective signal converter to optical pulses;
a plurality of receive optical subassemblies electrically coupled to respective signal converters of the plurality of signal converters, each receive optical subassembly comprising a respective receiver that converts optical pulses to digital signals which are sent to a respective signal converter; and
a fiber optical network optically coupled to the transmitters and receivers for enabling the plurality of controller area network nodes to communicate with each other, wherein the fiber optical network comprises a reflective optical star and a fiber bundle comprising a plurality of optical fibers which optically couple the plurality of transmit optical subassemblies and the plurality of receive optical subassemblies to the reflective optical star,
wherein each optical fiber of the plurality of optical fibers of the fiber bundle has a jacketed portion and a raw end; and
wherein the reflective optical star comprises:
an optical mixing rod optically coupled to the raw ends of the plurality of optical fibers of the fiber bundle;
a mixing rod sleeve that surrounds the optical mixing rod;
a fiber bundle sleeve that surrounds the raw ends of the plurality of optical fibers of the fiber bundle; and
a star outer housing that surrounds the fiber bundle sleeve and the mixing rod sleeve.

2. The system as recited in claim 1 , wherein an end face of each optical fiber of the plurality of optical fibers of the fiber bundle is bonded to an end face of the optical mixing rod.

3. The system as recited in claim 1 , wherein an end face of the fiber bundle sleeve and an end face of the mixing rod sleeve abut each other.

4. The system as recited in claim 1 , wherein an axial portion of the fiber bundle sleeve has a tapered internal surface which constrains the raw ends of the of the plurality of optical fibers of the fiber bundle.

5. The system as recited in claim 1 , wherein the reflective star coupler further comprises a mirror disposed at one end of the optical mixing rod.

6. The system as recited in claim 1 , wherein the fiber optical network further comprises a plurality of optical Y-couplers optically coupled to the reflective optical star, each optical Y-coupler comprising transmit and receive branches which are respectively optically coupled to the transmitter and receiver associated with a respective signal converter, and wherein the transmit branch of each optical Y-coupler comprises a first optical fiber having a first side face, the receive branch of each optical Y-coupler comprises a second optical fiber having a second side face that confronts the first side face, and each optical Y-coupler further comprises a layer of reflective material disposed between the first and second side faces of the transmit and receive branches.

7. The system as recited in claim 1 , wherein the star outer housing is provided with an access hole for injection of adhesive between the star outer housing and the fiber bundle sleeve and the mixing rod sleeve.

8. The system as recited in claim 1 , wherein each controller area network node of the plurality of controller area network nodes comprises a respective controller area network controller and a respective controller area network transceiver electrically coupled to the respective controller area network controller, the controller area network controllers being configured to communicate using bitwise arbitration.

9. The system as recited in claim 8 , wherein each signal converter of the plurality of signal converters comprises:
a first amplifier having differential input terminals respectively connected to CANH and CANL terminals of a respective controller area network transceiver and an output terminal;
an OR gate having first and second input terminals and an output terminal;
a first AND gate having a first input terminal connected to the output terminal of the first amplifier, a second input terminal configured and connected to receive an inverted bit from the output terminal of the OR gate, and an output terminal connected to a respective transmit optical subassembly;
a second AND gate having a first input terminal connected to receive an inverted bit from the output terminal of the first AND gate, a second input terminal connected to a respective receive optical subassembly, and an output terminal connected to the first input terminal of the OR gate; and
a second amplifier having an input terminal connected to the output terminal of the second AND gate, a first output terminal connected to the CANH terminal of the respective controller area network transceiver, and a second output terminal configured and connected output an inverted voltage signal to the CANL terminal of the respective controller area network transceiver.

10. The system as recited in claim 9 , further comprising a shift register having an input terminal connected to the output terminal of the second AND gate and an output terminal connected to the second input terminal of the OR gate.

11. A data communications system comprising:
a plurality of electrical devices configured for sending and receiving electrical signals representing data, wherein each of the electrical devices comprises a respective controller configured to broadcast messages, and a respective transceiver electrically coupled to the respective controller;
a plurality of signal converters electrically coupled to respective ones of the transceivers, each signal converter comprising electrical circuitry that converts differential signals to digital signals and vice versa;
a plurality of transmit optical subassemblies electrically coupled to respective signal converters of the plurality of signal converters, each transmit optical subassembly comprising a respective transmitter that converts digital signals from a respective signal converter to optical pulses;
a plurality of receive optical subassemblies electrically coupled to respective signal converters of the plurality of signal converters, each receive optical subassembly comprising a respective receiver that converts optical pulses to digital signals which are sent to a respective signal converter; and
a fiber optical network optically coupled to the transmitters and receivers for enabling the plurality of electrical devices to communicate with each other, wherein the fiber optical network comprises:
a reflective optical star;
a plurality of optical Y-couplers, each optical Y-coupler comprising a transmit branch that is optically coupled to a respective transmit optical subassembly via a respective plastic optical fiber of a first plurality of plastic optical fibers and a receive branch that is optically coupled to a respective receive optical subassembly via a respective plastic optical fiber of a second plurality of plastic optical fibers; and
a third plurality of plastic optical fibers which respectively optically couple the plurality of optical Y-couplers to the reflective optical star, wherein each plastic optical fiber of the third plurality of plastic optical fibers has a jacke

Assignees

• Boeing Co

Inventors

• Truong Tuong K
• Chan Eric Y
• Koshinz Dennis G
• Nguyen Kim Quan Anh
• Pang Barkhung Henry
• Ramey Sean M
• Jackson Timothy E

Classifications

• H04L2012/40215

  Controller Area Network CAN · CPC title

• G02B6/4246

  Bidirectionally operating package structures · CPC title

• H04B10/66

  Non-coherent receivers, e.g. using direct detection · CPC title

• H04L12/40 Primary

  Bus networks · CPC title

• H04B10/27

  Arrangements for networking · CPC title