JP2007281992A - Optical spatial communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical spatial communication device which prevents the incorrect acknowledgement about the cause of cutting in communication. <P>SOLUTION: When the communication is disconnected according to a certain cause in S3, it moves to S4. In S4, the level of receiving light is judged whether it is changed suddenly or not and when the receiving light is changed gradually, it moves to S5 and it is judged that the cutting of communication is caused by bad weather and an elapsed history is preserved in S6. Then it moves to the process in S7. When the level of receiving light is judged so that it is changed suddenly in S4 while the deviating amount of optical axis and the level of reception of light are dropped at the same time in S8, it is judged that it is instantaneous cutting due to obstacles in S9, and the elapse history is recorded together with a time in S10 and it moves to the process in S7. When the light receiving level is not deteriorated together with the change of deviating amount of optical axis upon change of the receiving optical level in S8, it is judged in S11 that the deviation of optical axis is due to gust, earthquake or the like and the elapse history is preserved in S12 together with the time and, thereafter, the alarm of abnormality is transmitted to the manager of a network in S13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical space communication apparatus that transmits information to a remote place via a light beam.

  In general, an optical space communication apparatus that performs communication by propagating a light beam in free space needs to reduce the divergence angle of the light beam as much as possible in order to communicate light power efficiently. However, if the light beam divergence angle is narrowed, the light beam is likely to be detached from the other device due to wind pressure or vibration of the building or installation base, distortion due to temperature fluctuation, angle fluctuation due to aging, etc., making stable communication difficult. It becomes.

  For this reason, there has been proposed an apparatus having an optical axis deviation correction function in which the light beam always faces the counterpart apparatus by correcting the angle change even if the angle of the apparatus changes. For this reason, the position of the light beam L from the counterpart device is detected using an optical position detection element.

  FIG. 6 shows a front view of the above-described optical position detecting element composed of the four divided photodiodes 1a to 1d. When the light spot S is incident on the photodiodes 1a to 1d, the position of the light spot S can be detected by comparing the outputs of the photodiodes 1a to 1d. A signal from the optical position detection element is processed as angle correction information and output to the drive circuit as a drive signal. The drive mechanism is driven by this drive signal and adjusted so that the outputs of the photodiodes 1 a to 1 d are all equal, that is, the position of the light spot S reaches the center of the light position detection element 1.

  In this way, optical axis deviation correction is performed so that the transmitted light is directed in the direction of the received light, that is, the direction of the counterpart device.

However, in the optical space communication device, communication disconnection occurs due to various factors, and depending on the cause of the communication disconnection, it may be necessary to take measures to restore communication. The following (a) to (c) can be considered as causes of the communication interruption.
(A) The amount of light from the counterpart device is insufficient due to the attenuation of the light beam due to worsening weather such as rain or snow.
(B) When an obstacle enters between the own device and the counterpart device.
(C) When the optical axis deviates due to external factors such as gusts and earthquakes.

  In the case of bad weather of (a), communication is restored if the weather recovers, and in the case of obstacle of (b), it is restored if the obstacle is removed from the optical path. The phenomenon of (a) and (b) is an operation state assumed for an optical space communication apparatus that performs information communication using a light beam. There is no need to issue an abnormal warning.

  However, in the case of (c) due to an external factor, communication does not recover even after a lapse of time, and it is necessary to perform a recovery operation by humans. Therefore, it is necessary to issue an abnormality warning to the network administrator.

  In order to solve this problem, Patent Document 1 discloses means for determining the cause of communication interruption based on the pattern of the change rate of the received light level and the communication interruption time.

JP 2003-188829 A

  However, in Patent Document 1, a case where an obstacle has entered between the own device and the counterpart device and a case where the optical axis is deviated due to an external factor such as a gust or an earthquake are determined based on the communication interruption time. Yes. Therefore, when an obstacle stays for a long time between the own device and the partner device, the communication is interrupted by the obstacle, but the optical axis shift occurs due to an external factor, and the communication is erroneously recognized. May end up.

  An object of the present invention is to provide an optical space communication device that solves the above-described problems and prevents erroneous recognition of the cause of communication interruption.

  In order to achieve the above object, the technical feature of the optical space communication device according to the present invention is an optical space communication device in which light is transmitted by being arranged facing each other at remote points, and a region that receives light from the counterpart device Are divided into a plurality of photoelectric conversion elements, an angle calculation unit for calculating an angle formed by the optical axis of the counterpart device and the optical axis of the own device based on the output of the photoelectric conversion element, and a total of the photoelectric conversion elements A total received light amount calculation unit for calculating a received light amount; a determination unit that determines a cause of communication disconnection based on a time change of an output value of the angle calculation unit and an output value of the total received light amount calculation unit; and Warning means for warning when it is determined that a communication interruption has occurred due to a deviation between the optical axis of the counterpart device and the optical axis of the own device.

  According to the optical space communication device according to the present invention, it is possible to accurately determine the cause of the communication disconnection, so that a communication disconnection due to an external factor that requires human work is quickly detected, and an abnormal warning is given. You can notify the network administrator.

  The present invention will be described in detail based on the embodiment shown in FIGS.

  FIG. 1 shows a configuration diagram of a space optical transmission apparatus according to the present embodiment, and shows only one of a pair of apparatuses for transmitting / receiving opposing light beams. In the housing 11, driving devices 14, 15, polarization beam splitter 16, beam splitter 17, lens 18, optical position, whose angles are displaced using transmission / reception optical lenses 12, 13, mirrors 14 a, 15 a from the counterpart device side, are located. The detection elements 19 are arranged in sequence. In the incident direction of the polarization beam splitter 16, a lens 20 and a light emitting element 21 including a semiconductor laser light source are provided, and in the branching direction of the beam splitter 17, a lens 22 and a light receiving element 23 are provided.

  The output of the optical position detection element 19 is connected to the control circuit 24, and the output of the control circuit 24 is connected to the drive devices 14 and 15 via the drive circuits 25 and 26, respectively.

  When laser light polarized so that the polarization direction is horizontal to the paper surface is emitted from the light emitting element 21 toward the lens 20 and the polarization beam splitter 16, the laser light reflected by the polarization beam splitter 16 is transmitted to the transmission / reception light lens 13, 12 and exits to the other device. At this time, the transmission / reception light lens 12 becomes a substantially horizontal light beam L having a slight spread.

  Further, the light beam L transmitted from the counterpart device passes through the transmission / reception light lenses 12 and 13 and the mirrors 14a and 15a, the polarization direction is set perpendicular to the paper surface, and is orthogonal to the transmission light. The light passes through the splitter 16 as it is and enters the beam splitter 17. Then, the light beam L is split at the beam splitter 17, most of the light beam L is reflected, enters the light receiving element 23 through the lens 22, and the other light beam transmitted through the beam splitter 17 passes through the lens 18 to be light. The light enters the position detection element 19.

  The signal obtained by the light position detecting element 19 is output to the drive circuits 25 and 26 via the control circuit 24 and is output to the drive devices 14 and 15 to adjust the direction of the light beam.

  FIG. 2 is a block circuit configuration diagram relating to the optical position detection element 19, and the optical position detection element 19 is constituted by four divided photodiodes 19a to 19d. Outputs of the individual photodiodes 19a to 19d are connected to received light amount detectors 31a to 31d for converting a voltage corresponding to the received light amount into a received light amount level value. The outputs of the received light amount detectors 31a to 31d are connected to an angle error calculator 32 and a received light amount calculator 33 that calculates the sum of the received light amounts.

  The outputs of the angle error calculation unit 32 and the received light amount calculation unit 33 are connected to a communication disconnection cause analysis unit 34 that determines the cause of communication disconnection from a temporal change. It is connected to an abnormality notification unit 35 that informs the device administrator of the cause.

  The light beam L transmitted from the counterpart device enters the light position detection element 19 as a light spot S, and each of the photodiodes 19a to 19d outputs a voltage corresponding to the area on which the light spot S is incident. Each output voltage of the photodiodes 19a to 19d is converted into a light reception level value by the light reception amount detection units 31a to 31d, and each light reception level value is output to the angle error calculation unit 32 and the light reception amount calculation unit 33. The angle error calculation unit 32 calculates the amount of optical axis deviation from the counterpart device, and the received light amount calculation unit 33 calculates the total light reception level of the optical position detection element 19.

  The optical axis deviation amount and the total light receiving level obtained in this way are input to the communication interruption cause analysis unit 34, and the communication interruption cause analysis unit 34 detects the communication interruption and analyzes the cause of the communication interruption. .

  FIG. 3 is a graph showing a change in the optical axis deviation amount and the total received light amount of the photodiodes 19a to 19d when the optical axis deviation occurs due to the external factor (c) described in the background art. When the counterpart device or the own device causes an optical axis shift from the position of the light spot S1 without the optical axis shift due to an external factor, the position of the light spot S along the optical axis shift from S1 to S4 in time series. And move. The amount of optical axis deviation increases with the movement of the light spot S, but the total amount of received light hardly changes as long as the light spot S is in the optical position detection element 19. When the position of the light spot S changes further than S3 and moves outward from the light position detecting element 19, the total amount of received light decreases.

  The amount of optical axis deviation is calculated from the difference in the amount of light received by each of the photodiodes 19a to 19d. Accordingly, as the light spot S moves outward from the optical position detection element 19, the difference in the amount of received light decreases, and the optical axis is reached when the light spot S completely moves outward from the optical position detection element 19. The amount of deviation is zero.

  4A and 4B are graphs showing changes in the amount of optical axis deviation and the total amount of light received when, for example, an obstacle enters the optical path and blocks the light beam as described in the background art. Show. When an obstacle enters the optical path from the state of the light spot S5 with no optical axis deviation and is blocked, the light spot changes from S5 to S8. Here, the position of the light spot S does not change, and the light intensity of the light spot S decreases by the amount of light shielded. Therefore, as the obstacle enters the optical path, the amount of optical axis deviation increases and the total amount of received light decreases.

  As described above, the temporal change in the optical axis deviation and the total received light quantity before the communication interruption is stored in the memory, and if the fluctuation range of the total received light quantity is within a certain range at the time of the optical axis deviation change, it is external. Judged as optical axis misalignment due to factors. Otherwise, it can be determined that an obstacle has entered the optical path and has blocked the light beam.

  FIG. 5 shows a flowchart of the communication disconnection detection and communication disconnection cause analysis processing. First, when analysis processing is started in step S1, the received light level of the light position detecting element 19 is acquired by the received light amount calculation unit 33 in step S2, and then in step S3, the received light level acquired in step S2. To determine whether or not the communication is interrupted. In the normal communication state, the process returns to step S2, and steps S2 and S3 are repeated. If the communication is interrupted for some reason, the process proceeds to step S4.

  In step S4, it is determined whether or not the rate of change of the received light level has changed abruptly. If the received light level has gradually changed, the process proceeds to step S5, where it is determined that communication has been interrupted due to bad weather, the history is stored in the memory in step S6, and the process proceeds to step S7.

  If it is determined in step S4 that the received light level has changed abruptly, it is determined in step S8 whether there is a momentary interruption due to an obstacle or off-axis due to an external factor. That is, it is determined whether or not the received light level obtained by the received light amount calculation unit 33 has decreased along with the change in the light shift amount obtained by the angle error calculating unit 32. The factors that cause the received light level to drop to the level at which communication is interrupted at a stretch from maintaining the received light level above a certain level are the case of an optical axis shift due to an external factor, and an obstacle entering the optical path. However, there can be two ways of blocking light.

  If the light shift amount and the light reception level are simultaneously reduced, it is determined in step S9 that there is an instantaneous interruption due to an obstacle, and in step S10, the elapsed history is recorded in the memory with time, and the process proceeds to step S7.

  In step S8, if the amount of light deviation does not change even if the light reception level changes, in step S11, the elapsed history is stored in the memory with time in step S12 as the optical axis deviation due to an external factor. After that, an abnormality warning is sent to the network administrator.

  In this way, when the communication interruption cause analysis unit 34 determines that the optical axis shift is caused by an external factor, the abnormality notification unit 35 is notified of the occurrence of the abnormality, and the abnormality notification unit 35 that has received the notification displays a warning, Notify the system administrator of the occurrence of an abnormality through warning sound and communication. In this case, since the optical axis is off due to an external factor, it does not return until the reset start. Therefore, when the external factor is removed and the reset start is pressed, the process starts from step S1.

  In step S7, the received light level is acquired. In step S14, it is determined whether or not the received light level is equal to or higher than the communication disconnection level. If it is equal to or higher than the communication disconnection level, the process proceeds to step S15, the level recovery is stored in the elapsed history with time, and the process returns to step S2.

It is a block diagram of an optical space communication apparatus. It is a block circuit block diagram regarding an optical position detection element. It is a graph which shows the change of the optical axis deviation | shift amount and the total light reception amount in the case of the optical axis deviation | shift by an external factor. It is a graph of the change of the optical axis deviation | shift amount and total light reception amount when an obstruction approachs on an optical path and interrupts | blocks light. It is an operation | movement flowchart figure. It is a front view of the element for position detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Case 14, 15 Drive mechanism 16 Polarization beam splitter 17 Beam splitter 19 Optical position detection element 19a-19d Photodiode 21 Light emission element 23 Light reception element 24 Control circuit 25, 26 Drive circuit 31a-31d Light reception amount detection part 32 Angle error calculation Unit 33 received light amount calculation unit 34 communication disconnection cause analysis unit 35 abnormality notification unit

Claims (6)

  In an optical space communication device that communicates with light by opposingly arranging between distant points, the photoelectric conversion element divided into a plurality of regions that receive light from the counterpart device, and the output of the photoelectric conversion element An angle calculation unit that calculates an angle formed by the optical axis of the counterpart device and the optical axis of the own device, a total received light amount calculation unit that calculates a total received light amount of the photoelectric conversion element, an output value of the angle calculation unit, and the Determining means for determining a cause of communication disconnection based on a time change of an output value of the total received light amount calculation unit; and when the determining means causes the optical axis of the counterpart device to deviate from the optical axis of the own device, the communication disconnection An optical space communication device comprising warning means for warning when it is determined that the error has occurred.   If the output value of the total received light amount calculation unit is within a predetermined range when the output value of the angle calculation unit changes outside the predetermined range, 2. The optical space communication apparatus according to claim 1, wherein it is determined that the optical axis is shifted between the optical axis and the own apparatus.   When the output value of the angle calculation unit and the output value of the total received light amount calculation unit are simultaneously changed outside a predetermined range, the determination unit determines that the optical axis of the counterpart device and the optical axis of the device itself The optical space communication apparatus according to claim 1, wherein the optical space communication apparatus is not determined to be a deviation.   When the change speed when the output value of the total received light amount calculation unit changes outside a predetermined range is equal to or lower than a predetermined speed, the determination means determines the optical axis of the counterpart device and the own apparatus. The optical space communication apparatus according to any one of claims 1 to 3, wherein it is not determined that the optical axis is deviated from the optical axis.   The optical space communication apparatus according to any one of claims 1 to 4, wherein the photoelectric conversion element is a quadrant photodiode. The optical space communication apparatus according to claim 1, further comprising a storage unit that stores an output value of the angle calculation unit and an output value of the total received light amount calculation unit.

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