JP5985948B2 - Optical communication system - Google Patents

Description

  The present invention relates to an optical communication system.

  For example, in an in-vehicle optical communication system, it is required to support various devices such as HD (High-Definition) video, mobile phones, and tablet terminals. ing. On the other hand, in-vehicle optical communication systems are required to have higher reliability than conventional systems, and there is a so-called fault tolerance system that operates normally as a network even if a malfunction occurs in some of the components. It is necessary.

  As a light source used in such an optical communication system, there is a surface emitting laser described in Patent Document 1, for example. This surface emitting laser is a vertical cavity surface emitting laser (VCSEL), and a first mesa set and a second mesa set connected by different wiring layers are arranged on a rotation target with respect to a reference point on a substrate. In addition, the light emission point of the laser can be switched while suppressing the optical axis shift.

JP 2006-302981 A

  When incorporating a light source such as a VCSEL into the above-described optical communication system for in-vehicle use, the reliability of the light source is still insufficient. At present, in order to reduce the initial failure rate, burn-in tests are performed to apply temperature and electrical stress, and a standard for failure due to mounting failure or wear is established. However, for example, there is a problem that cannot be discriminated even by a burn-in test, such as a sudden operation stop caused by a crystal defect. Therefore, a configuration capable of easily realizing fault tolerance on the system side is desired.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical communication system capable of operating a network normally even when a malfunction occurs in some of the components.

  To solve the above problems, an optical communication system according to the present invention includes a pair of optical signal transmission units that transmit optical signals and an optical signal reception unit that receives optical signals transmitted from the optical signal transmission unit. An optical communication system comprising an optical transceiver, wherein the optical signal transmitter and the optical signal receiver are connected to each other via an optical fiber, and the optical transceiver includes a plurality of light emitting units constituting the optical signal transmitter A light intensity detection unit for detecting the light intensity of the optical signal from the other party optical transceiver received by the optical signal receiving unit, and detection information regarding the light intensity of the optical signal detected by the light intensity detection unit A detection information transmission unit to be transmitted to the device, a detection information reception unit to receive the detection information from the counterpart optical transceiver, the detection information received by the detection information reception unit, and a threshold table relating to the light intensity of the light emitting unit held in advance And based on the comparison result It is characterized by comprising a control unit for switching the light emitting unit used in the optical signal transmitting unit.

  In this optical communication system, in a pair of optical transceivers, the optical intensity of an optical signal transmitted from a counterpart optical transceiver is detected, and detection information indicating a detection result is transmitted to the counterpart optical transceiver. In the optical transmitter / receiver that has received the detection information, the control unit switches the light emitting unit by comparing the detection information with a threshold table that is held in advance. Therefore, in this optical communication system, even if a failure occurs in some of the components, fault tolerance can be easily realized on the system side. In addition, in this optical communication system, the reliability of the entire system can be ensured by switching control of the light emitting unit regardless of the reliability of the light emitting unit itself, so the burn-in test process can be omitted, and the cost of system construction Can be reduced.

  Moreover, it is preferable that an optical signal transmission part is comprised by VCSCEL provided with the several light emission part. When a VCSEL is used as a light source, a plurality of light emitting portions that selectively emit light can be formed close to each other. Therefore, the optical signal transmitter can be formed compactly.

  The plurality of light emitting units are preferably arranged so as to be rotationally symmetric with respect to the optical axis center of the optical fiber. In this case, the coupling between the light emitting unit and the optical fiber can be made uniform.

  Moreover, it is preferable that the plurality of light emitting units are arranged so that each emitted light is coupled to the same core of the optical fiber via a lens. Thereby, a single optical fiber can be applied to a plurality of light emitting units, and the configuration of the optical communication system can be simplified.

  According to the optical communication system of the present invention, the network can be operated normally even if a defect occurs in some of the components.

It is a figure which shows schematic structure of the optical communication system which concerns on one Embodiment of this invention. It is a block diagram which shows the functional component of the optical communication system shown in FIG. It is a figure which shows schematic structure of the light emitting element used for an optical signal transmission part. It is a figure which shows the coupling | bonding state of a light emitting element and an optical fiber. It is a figure which shows an example of the threshold value table stored in memory. It is a sequence diagram which shows operation | movement of an optical communication system.

  Hereinafter, preferred embodiments of an optical communication system according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an optical communication system according to an embodiment of the present invention. As shown in the figure, the optical communication system 1 is configured by connecting a pair of optical transceivers T (T 1, T 2) with an optical fiber 2. The optical communication system 1 is used as, for example, an in-vehicle network system mounted on an automobile or the like, and a network loop is formed between optical transceivers T1 and T2 arranged at predetermined positions of a vehicle body.

  As shown in FIG. 2, the optical transceivers T1 and T2 include an optical signal transmitter 11 that transmits an optical signal, an optical signal receiver 12 that receives an optical signal, and an optical signal receiver as shown in FIG. 12, a memory 13 for storing information based on the optical signal received at 12, a microcomputer 14 for reading the information stored in the memory 13, and a NIC (Network Interface Card) 15 for processing the information read by the microcomputer 14. A controller (control unit) 16 that controls the operation of the optical signal transmission unit 11. In FIG. 2, for convenience of showing the connection state, the positions of some of the components are different between the optical transceiver T1 and the optical transceiver T2, but the components held by both are the same. .

  As illustrated in FIG. 3, the optical signal transmission unit 11 is configured by a VCSEL 21 including a plurality of light emitting units 23, for example. The VCSEL 21 has three light emitting portions 23 a to 23 c on one side of the substrate 22, three anode bonding pads 24 corresponding to the respective light emitting portions 23, and a cathode bonding pad 25 common to each light emitting portion 23. doing.

  The light emitting unit 23 is disposed in the vicinity of the central portion on the one surface side of the substrate 22, and is disposed in an annular shape so as to be rotationally symmetric with respect to the optical axis center of the optical fiber 2. The distance between the light emission parts 23 and 23 is 20 micrometers, for example. The optical fiber 2 to which the light emitted from the light emitting unit 23 is coupled is, for example, a multimode optical fiber having a core diameter of 50 μm. As shown in FIG. 4, the light emitting unit 23 is arranged so that each emitted light is coupled to the same core 2 a of the optical fiber 2 via the condenser lens R.

  Further, as shown in FIG. 2, a thermometer 17 that detects the temperature around the light emitting unit 23 is disposed in the vicinity of the VCSEL 21. As the thermometer 17, for example, a sensor using a semiconductor junction is used. The thermometer 17 detects the temperature around the light emitting unit 23 at all times or at a constant cycle, and outputs detection information indicating the detected temperature to the memory 13.

  This optical signal transmission unit 11 has a function as a detection information transmission unit 31 that transmits detection information related to the light intensity of an optical signal detected by a light intensity detection unit 32, which will be described later, to the counterpart optical transceiver T. . When the optical signal transmission unit 11 receives a data string in which the detection information is incorporated from the NIC 15, the optical signal transmission unit 11 transmits an optical signal including the data string to the optical transceiver T of the other party.

  The optical signal receiving unit 12 is configured by a photodiode using, for example, InGaAs as a photoelectric element. When receiving the optical signal from the counterpart optical transceiver T, the optical signal receiving unit 12 outputs a data string included in the optical signal to the NIC 15. The optical signal receiving unit 12 has a function as a light intensity detecting unit 32 that detects the light intensity of the optical signal from the counterpart optical transceiver T. The optical signal receiving unit 12 detects the optical intensity of the optical signal received from the optical transceiver T of the other party at all times or at a constant cycle, and the detection information indicating the detected optical intensity is digitally converted by the A / D converter 18. Output to the memory 13.

  Furthermore, the optical signal receiving unit 12 has a function as a detection information receiving unit 33 that receives detection information related to the light intensity of the optical signal of the optical signal transmitting unit 11 of the own device from the optical transceiver T of the other party. The optical signal receiver 12 converts the received detection information related to the optical intensity of the optical signal of the optical signal transmitter 11 of the own device into an electrical signal and outputs the electrical signal to the NIC 15.

  The memory 13 is a part that receives and stores light intensity detection information about the counterpart optical transceiver T from the optical signal receiver 12. The memory 13 is a part that receives and stores detection information related to the light intensity of the optical signal for the optical signal transmitter 11 of the own device from the microcomputer 14. Further, the memory 13 stores a threshold value table regarding the light intensity of the light emitting unit 23. FIG. 5 shows an example of the threshold value table stored in the memory. In the example shown in the figure, the horizontal axis represents temperature and the vertical axis represents light intensity, and the threshold value of the light intensity of the light emitting unit 23 is set according to the temperature. This threshold value table may be a setting common to the light emitting units 23a to 23c, or may be a setting for each of the light emitting units 23a to 23c.

  The microcomputer 14 is a part that reads the detection information of the light intensity of the counterpart optical transceiver T stored in the memory 13 via the I2C interface. The microcomputer 14 reads the detection information from the memory 13 at regular intervals, and outputs the read detection information to the NIC 15. The microcomputer 14 is a part that receives detection information regarding the light intensity of the optical signal for the optical signal transmission unit 11 of the own device from the NIC 15. The microcomputer 14 outputs the received detection information to the memory 13 for writing.

  The NIC 15 is a part that encodes the detection information of the light intensity of the counterpart optical transceiver T received from the microcomputer 14. The encoded detection information is added to the head portion of the data string included in the optical signal, for example. Also, the NIC 15 outputs detection information regarding the light intensity of the optical signal of the own optical signal transmission unit 11 received from the optical signal reception unit 12 to the microcomputer 14.

  The controller 16 compares the detection information related to the light intensity of the optical signal transmission unit 11 received by the optical signal receiving unit 12 with the threshold table related to the light intensity of the light emitting unit 23 previously stored in the memory 13. This is a part for switching the light emitting unit 23 used in the optical signal transmitting unit 11 based on the comparison result. More specifically, the controller 16 refers to the memory 13 constantly or at a constant cycle, and detection information regarding the light intensity of the optical signal of the own optical signal transmission unit 11 stored in the memory 13 and a threshold table. And read. Further, the controller 16 reads out the detection result of the temperature around the light emitting unit 23 by the thermometer 17 from the memory 13. Then, the controller 16 determines whether the light intensity exceeds the threshold value under the detected temperature.

  As a result of the comparison, if it is determined that the light intensity exceeds the threshold, the controller 16 determines that the light emitting unit 23 of the VCSEL 21 that is currently driven is normal, and continues to use it. At this time, the controller 16 controls the drive current of the light emitting unit 23 based on the detected light intensity so that the light amount of the light emitting unit 23 becomes an appropriate value within a range exceeding the threshold value. On the other hand, when it is determined that the light intensity is equal to or lower than the threshold value, it is determined that the light emitting unit 23 of the VCSEL 21 that is currently driven is abnormal, and the light emitting unit 23 to be driven is switched to another light emitting unit 23. In this embodiment, for example, if the light emitting unit 23 to be initially driven is the light emitting unit 23a, if it is determined that there is an abnormality in the light emitting unit 23a, the light emitting unit 23b is used next and the light emitting unit 23b is used. If it is determined that there is an abnormality, the light emitting unit 23c is used next.

  Subsequently, the operation of the optical communication system 1 having the above-described configuration will be described. FIG. 6 is a sequence diagram showing the operation of the optical communication system.

  As shown in the figure, in the optical communication system 1, for example, an optical signal is transmitted from the optical transceiver T1 to the optical transceiver T2 (step S01). In the optical transceiver T2, the optical intensity of the optical signal received by the optical signal receiver 12 is detected (step S02). The detection information received in step S02 is digitally converted by the optical transceiver T2, temporarily stored in the memory 13, read out by the microcomputer 14, encoded by the NIC 15, and incorporated in the data sequence of the optical signal ( Step S03). Then, the optical signal incorporating the detection information is transmitted from the optical transceiver T2 to the optical transceiver T1 (step S04).

  In the optical transceiver T1 that has received the optical signal in which the detection information is incorporated, the optical signal is converted into an electrical signal and output to the NIC 15. Further, the microcomputer 14 reads the detection information from the NIC 15 and stores it in the memory 13. Next, the controller 16 compares the light intensity of the optical signal indicated by the detection information with the threshold value table (step S05), and controls the light emitting unit 23 based on the comparison result (step S06).

  In step S06, it is determined whether the light intensity of the optical signal exceeds the threshold value under the temperature detected by the thermometer 17. And when it is judged that the light emission part 23 is normal, use of the light emission part 23 currently driven is continued and control of the drive current to the light emission part 23 is implemented. When it is determined that the light emitting unit 23 is abnormal, the light emitting unit 23 to be driven is switched to another light emitting unit 23.

  As described above, in the optical communication system 1, in the pair of optical transceivers T1 and T2, the optical intensity of the optical signal transmitted from the counterpart optical transceiver T is detected, and the detection information indicating the detection result is detected. Transmit to the optical transceiver T. In the optical transceiver T that has received the detection information, the controller 16 switches the light emitting unit 23 by comparing the detection information with a threshold table held in advance. Therefore, in this optical communication system 1, even if a malfunction occurs in some of the components, fault tolerance can be easily realized on the system side. Further, in this optical communication system 1, since the reliability of the entire system can be ensured by switching control of the light emitting unit 23 regardless of the reliability of the light emitting unit 23 itself, the burn-in test process can be omitted. Construction costs can be reduced.

  Further, in the optical communication system 1, when it is determined that the light emitting unit 23 is normal, the use of the currently driven light emitting unit 23 is continued and the drive current to the light emitting unit 23 is controlled. . As described above, by monitoring the light intensity of the light emitting unit 23 on the network, the automatic power control of the light emitting unit 23 can be realized.

  Moreover, in the optical communication system 1, the optical signal transmission part 11 is comprised by VCSCEL21 provided with several light emission parts 23a-23c. When a VCSEL is used as the light source, the light emitting portions 23a to 23c that selectively emit light can be formed close to each other. Therefore, the optical signal transmitter 11 can be formed compactly. Further, the light emitting units 23 a to 23 c are arranged so as to be rotationally symmetric with respect to the optical axis center of the optical fiber 2, so that the coupling between the light emitting units 23 a to 23 c and the optical fiber 2 can be made uniform. The change in the amount of light due to the arrangement of the light emitting unit 23 can be suppressed.

  Furthermore, in the optical communication system 1, the light emitting units 23 a to 23 c are arranged so that each emitted light is coupled to the same core 2 a of the optical fiber 2 via the condenser lens R. Thereby, the single optical fiber 2 can be applied with respect to the several light emission parts 23a-23c, and simplification of the structure of the optical communication system 1 is achieved.

  DESCRIPTION OF SYMBOLS 1 ... Optical communication system, 2 ... Optical fiber, 2a ... Core, 11 ... Optical signal transmission part, 12 ... Optical signal receiving part, 16 ... Controller (control part), 21 ... VCSEL, 23 (23a-23c) ... Light emission part , 31 ... detection information transmission unit, 32 ... light intensity detection unit, 33 ... detection information reception unit, R ... condensing lens, T1, T2 ... optical transmission / reception device.

Claims (4)

A communication system formed by connecting an optical transceiver one pair optical fiber,
Each of the pair of optical transceivers is
An optical signal transmitter that transmits an optical signal to the optical transceiver of the other party via the optical fiber;
An optical signal receiving unit that receives an optical signal transmitted from the counterpart optical transceiver via the optical fiber;
A plurality of light emitting units constituting the optical signal transmitting unit;
A light intensity detector for detecting the light intensity of the optical signal from the optical transceiver of the previous SL party,
A storage unit for storing detection information indicating a detection result by the light intensity detection unit;
A detection information transmission unit that adds the detection information stored in the storage unit to the optical signal and transmits the optical signal to the optical transceiver of the other party;
A detection information receiving unit that receives detection information transmitted from the counterpart optical transceiver in response to transmission of the optical signal by the optical signal transmitting unit ;
Control for comparing the detection information received by the detection information receiving unit with a threshold table relating to the light intensity of the light emitting unit held in advance, and switching the light emitting unit used in the optical signal transmitting unit based on the comparison result And an optical communication system.   2. The optical communication system according to claim 1, wherein the optical signal transmission unit is configured by a VCSCEL including the plurality of light emitting units.   The optical communication system according to claim 1, wherein the plurality of light emitting units are arranged to be rotationally symmetric with respect to an optical axis center of the optical fiber.   4. The light according to claim 1, wherein each of the plurality of light emitting units is arranged such that each emitted light is coupled to the same core of the optical fiber via a lens. Communications system.

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