JP4375076B2 - Optical wireless transmission system - Google Patents

Description

The present invention relates to an optical wireless transmission system, and more particularly, relates to suppress optical wireless transmission system signal error caused by shields in the space transmission path.

  The optical wireless system for propagating light in free space has a higher degree of freedom in installation and less restrictions on places, etc., compared to the case of connecting by wire.

However, in optical wireless transmission in the atmosphere, light path shielding due to rain, fog, smoke, birds, and the like causes signal errors and causes reception interruption . In order to prevent such signal errors and reception interruptions due to such optical path shielding, conventionally, a spatial diversity system using a plurality of optical transmission systems, that is, a plurality of light sources and a plurality of light receivers, has been employed. In digital transmission, error correction using an error correction code is also performed.

Further, from a viewpoint different from data transmission by space diversity, systems disclosed in Patent Documents 1 and 2 are known as transmission systems using a plurality of light sources and a plurality of light receivers. For example, Patent Document 1 describes a signal transmission system in which an optical transmission / reception device for search is provided in addition to an optical transmission / reception device for communication. Patent Document 2 describes a signal transmission system in which a visible light source for confirmation is provided separately from an infrared light source for communication that cannot be confirmed with the naked eye.
JP-A-8-129678 JP-A-9-069815

  In the spatial diversity method using a plurality of light sources and a plurality of light receivers, a plurality of optical transmission systems are prepared, and the transmitter / receiver becomes complicated, leading to an increase in cost. Furthermore, when a plurality of light sources are shielded at the same time, it is inevitable that a signal error will occur. Therefore, it is necessary to arrange the light sources apart from each other. This means that it is necessary to prepare a plurality of optical transmission devices and to prepare a distribution device and a transmission path for distributing data to these optical transmission devices. This also greatly increases the cost of the system.

An object of the present invention is to provide an optical wireless transmission system capable of suppressing signal errors even when a shield such as a bird enters a space transmission path.

The optical wireless transmission system according to the present invention is an optical wireless transmission system that transmits and receives signals between a first optical transmission / reception device and a second optical transmission / reception device via a spatial transmission path. The first optical transmission / reception device includes a first signal light generation device that generates a first signal light directed to the second optical transmission / reception device, and a second signal light from the second optical transmission / reception device. A first receiver for receiving light, and a shielding member disposed around the first receiver for receiving light and blocking the input of the second signal light to the first receiver. The first shielding detectors to be detected before interference with the input to the first receiving light receiver and the detection outputs of the first shielding detectors according to the detection outputs of the first shielding detectors. And a first communication control device that temporarily stops the output of the first signal light from the first signal light generator when the output of the shield detector indicates the presence of the shield. The second optical transmission / reception device includes a second signal light generation device that generates the second signal light and a second reception light that receives the first signal light from the first optical transmission / reception device. a light receiving device, the accordance with the transmission stop of the first signal light of the first optical transceiver, a second communication to pause the output of the second signal light from the signal light generator of this second And a control device.

The optical wireless transmission system according to the present invention is an optical wireless transmission system that transmits and receives signals between a first optical transmission / reception device and a second optical transmission / reception device via a spatial transmission path. The first optical transmission / reception device includes a first signal light generation device that outputs a first signal light directed to the second optical transmission / reception device to a spatial transmission path, and a first signal light generation device from the second optical transmission / reception device. A first receiving light receiver for receiving the second signal light, and an obstacle to the input of the second signal light to the first receiving light receiver disposed around the first receiving light receiver. According to the detection outputs of the plurality of first shielding detectors and the plurality of first shielding detectors that detect the shielding object before the interference to the input to the first receiving light receiver, A first communication control device for temporarily stopping the output of the first signal light from the first signal light generator when the output of the first shield detector indicates the presence of the shield; It has. The second optical transmission / reception device receives the second signal light generation device that outputs the second signal light to the spatial transmission path, and the first signal light from the first optical transmission / reception device. A second receiving light receiver and a shielding object disposed around the second receiving light receiver and obstructing the input of the first signal light to the second receiving light receiver; A plurality of second shield detectors that detect before interference with the input to the receiving light receiver, and any second shield detector according to the detection outputs of the plurality of second shield detectors And a second communication control device that temporarily stops the output of the second signal light from the second signal light generator when the output of the signal indicates the presence of the shielding object. .

  According to the present invention, the intrusion of the shielding object into the space transmission path is detected before the shielding object interferes with the input of the signal light to the receiving light receiver, and transmission is temporarily stopped according to the detection result. The signal transmission error due to the intrusion of the shield can be greatly reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic block diagram of a first embodiment of the present invention. The optical transmission / reception device 10A transmits data D1 to the optical transmission / reception device 10B via the spatial transmission path 12, and the optical transmission / reception device 10B transmits data D2 to the optical transmission / reception device 10A via the spatial transmission path 12.

  The configuration of the optical transceiver 10A will be described. The optical transceiver 10A includes a light source 16A that outputs signal light, a light receiving device 18A for receiving signals, and a plurality of light receiving devices 20A for detecting optical path shielding as optical elements. FIG. 2 is a plan view showing an arrangement example of the light source 16A, the light receiver 18A, and the light receiver 20A. The plurality of light receivers 20A are arranged at substantially equal angular intervals on the same radius around the light source 16A and the light receiver 18A. In this embodiment, the optical transceivers 10A and 10B project signal light with a beam that diffuses in accordance with transmission. The light receiver 20A is arranged so as to be positioned in the periphery within the spread range of the signal light beam projected from the optical transceiver 10B. Specifically, the signal light beam output from the light source 16A of the optical transmission / reception device 10A is adjusted so as to expand to include the light receiver 20B of the optical transmission / reception device 10B in the beam peripheral portion, and the light source 16B of the optical transmission / reception device 10B. The signal light beam output from is adjusted so as to expand to the extent that the light receiver 20A of the optical transceiver 10A is included in the beam peripheral portion.

  The communication control device 22A applies data D1 input from an external device (not shown) to the buffer 24A, and controls data writing and reading of the buffer 24A. The buffer 24A temporarily stores the data D1 from the communication control device 22A, and applies the storage data D1 to the drive circuit 26A in accordance with a read command from the communication control device 22A or automatically. The drive circuit 26A causes the light source 16A to emit light according to the data D1 from the buffer 24A. As a result, the light source 16A outputs the signal light beam toward the optical transceiver 10B.

  The optical transceiver 10B has the same configuration as the optical transceiver 10A. The optical transmission / reception device 10B includes a light source 16B, a signal receiving light receiver 18B, and a plurality of light path shielding detection light receivers 20B as optical elements. These optical elements 16B, 18B, and 20B are shown in FIG. The light source 16A, the light receiver 18A, and the light receiver 20A are arranged in the same manner as in the arrangement example.

  The signal identification device 28A identifies the data D2 from the output signal of the light receiver 18A, and applies the identified data D2 to the communication control device 22A. Further, the optical path interruption identifying device 30A identifies whether or not the shielding object 14 has entered the spatial transmission path 12 based on the presence or absence of the output of the light receiver 20A, and applies the identification result to the communication control device 22A. The operation of the communication control device 22A when the optical path blocking identification device 30A detects the intrusion of the shielding object 14 will be described in detail later.

  The communication control device 22B applies data D2 input from an external device (not shown) to the buffer 24B, and controls data writing and reading of the buffer 24B. The buffer 24B temporarily stores data D2 from the communication control device 22B, and applies the stored data D2 to the drive circuit 26B in accordance with a command from the communication control device 22B or automatically. The drive circuit 26B causes the light source 16B to emit light according to the data D2 from the buffer 24B.

  The signal identification device 28B identifies the data D1 from the output signal of the light receiver 18B, and applies the identified data D1 to the communication control device 22B. Further, the optical path cutoff identifying device 30B identifies whether or not the shielding object 14 has entered the spatial transmission path 12 based on the presence or absence of the output of the light receiver 20B, and applies the identification result to the communication control device 22B. When the optical path blocking identification device 30B detects the intrusion of the shielding object 14, the communication control device 22B operates in the same manner as the communication control device 22A.

  First, transmission of data D1 from the optical transceiver 10A to the optical transceiver 10B will be described. The communication control device 22A applies data D1 input from an external device (not shown) to the buffer 24A. When the communication control device 22A does not detect the shielding object 14 in the spatial transmission path 12, the communication control device 22A simply uses the buffer 24A for rate adjustment. Data D1 read from the buffer 24A in accordance with the transmission rate on the spatial transmission path 12 is applied to the drive circuit 26A. The drive circuit 26A drives the light source 16A according to the data D1 from the buffer 24A to emit light. Thereby, the light source 16A outputs the signal light beam carrying the data D1 toward the light receiver 18B of the optical transceiver 10B. However, the signal light beam output from the light source 16A is incident not only on the light receiver 18B but also on a plurality of light receivers 20A arranged around the light receiver 18B.

  The light receiver 18B converts the signal light from the light source 16A into an electrical signal. The signal identification device 28B identifies the data D1 from the output of the light receiver 18B. If there is no transmission error, the signal identification device 28B outputs data D1.

  Similarly, the light source 16B of the optical transmission / reception device 10B emits signal light carrying the data D2 toward the light receiver 18A of the optical transmission / reception device 10A. This signal light is incident not only on the light receiver 18A but also on a plurality of light receivers 20A arranged around the light receiver 18A.

  If the shield 14 is not present between the light receiver 20A and the light source 16B, the output signal light of the light source 16B is incident on the light receiver 20A, and the light receiver 20A outputs an electrical signal corresponding to the incident signal light. To do. When the shield 14 is present between the light receiver 20A and the light source 16B, the output signal light of the light source 16B is not incident on the light receiver 20A, and the light receiver 20A does not output an electrical signal. Therefore, by monitoring the output level of the light receiver 20A, the shield 14 can transmit a spatial transmission before blocking the light path between the light source 16A and the light receiver 18B or the light path between the light source 16B and the light receiver 18A. Intrusion of the shield 14 into the road 12 can be detected. The optical path cutoff identifying device 30A identifies whether or not the shielding object 14 has entered the spatial transmission path 12 based on the output level of the light receiver 20A, and notifies the communication control device 22B of the identification result. When any one of the optical path interruption identifying devices 30A notifies the communication control apparatus 22A of the optical path interruption, the communication control apparatus 22A stops reading data from the buffer 24A until there is no optical path interruption. As a result, the light source 16A stops outputting signal light, and data transmission from the optical transceiver 10A to the optical transceiver 10B is temporarily stopped.

  When the light source 16A temporarily stops the output of the signal light, the output levels of the light receiver 18B and all the light receivers 20B are lowered in the optical transceiver 10B. As a result, the communication control device 22B can know that the optical transmission / reception device 10A has temporarily stopped data transmission, and accordingly, the communication control device 22B temporarily stops transmission of data D2 toward the optical transmission / reception device 10A. The communication control device 22B waits for the data transmission of the optical transmission / reception device 10A to resume.

  After stopping data transmission for a certain time, the communication control device 22A instructs the drive circuit 26A to cause the light source 16A to output test light for investigating the presence or absence of the shield 14 on the spatial transmission path 12. Since this test light is merely used to confirm whether or not the shield 14 still exists on the spatial transmission path 12, it may be, for example, either continuous (CW) light or pulsed light.

  If there is no shield 14 on the spatial transmission path 12, all the light receivers 20B of the optical transceiver 10B receive the test light and the output level thereof increases. The all-optical path blocking identification device 30B notifies the communication control device 22B that there is no shielding object 14 on the spatial transmission path 12. In response to this notification, the communication control device 22B resumes reading the data D2 from the buffer 24B. The drive circuit 26B drives the light source 16B according to the data D2 from the buffer 24B. The light source 16B outputs the signal light that carries the data D2 toward the optical transceiver 10A. Thereby, the transmission of the data D2 from the optical transceiver 10B to the optical transceiver 10A is resumed.

  The light receiver 18A receives the signal light from the light source 16B, and the signal identification device 28A identifies the data D2 from the output signal of the light receiver 18A, and supplies the reception data D2 to the communication control device 22A.

  At the same time, the plurality of light receivers 20A also receive the signal light from the light source 16B. The all-optical-path cutoff identifying device 30A identifies from the output level of the corresponding light receiver 20A that there is no shield 14 on the spatial transmission path 12, and notifies the communication control unit 22A accordingly. In accordance with this notification, the communication control device 22A stops the output of the test light and reads the continuation of the data D1 from the buffer 24A. The drive circuit 26A drives the light source 16A according to the data D1 from the buffer 24A and outputs signal light. In this way, transmission of data D1 from the optical transceiver 10A to the optical transceiver 10B is resumed.

  Even if the test light is output, if the output level of any one of the light receivers 20B is low, the shielding object 14 still exists on the spatial transmission path 12. In this case, the communication control device 22B waits for the output levels of all the light receivers 20B to rise while keeping the transmission of the data D2 stopped. Since the transmission of the data D2 is not resumed, the optical transceiver 10A continues to emit the test light without resuming the transmission of the data D1.

  Although it has been described that one optical transmitter / receiver 10A outputs test light after the data transmission by the shield 14 is stopped, of course, both optical transmitter / receivers 10A, 10B output test light after a certain period of time after data transmission is stopped. You may make it do. In that case, the time from the stop of data transmission to the output of the test light may be the same or different in both the optical transceivers 10A and 10B.

  FIG. 3 shows a schematic block diagram of the second embodiment of the present invention. The same components as those in the embodiment shown in FIG.

  In the embodiment shown in FIG. 3, polarized waves that are orthogonal to each other, that is, P wave and S wave are used depending on the data transmission direction. For example, P waves are used for data transmission from the optical transceiver 40A to the optical transceiver 40B, and S waves are used for data transmission from the optical transceiver 40B to the optical transceiver 40B. Therefore, a polarization multiplexer / demultiplexer 42A and a projection / condensing lens 44A are added to the optical transmission / reception device 10A as components of the optical transmission / reception device 40A, and a configuration of the optical transmission / reception device 10B is added to the optical transmission / reception device 40B. A polarization multiplexer / demultiplexer 42B and a projection / condensing lens 44B are added as elements. The polarization multiplexers / demultiplexers 42A and 42B are so-called polarization beam splitters (PBS).

  The operation of the changed part will be described. The light source 16A of the optical transceiver 40A outputs P-wave signal light or test light. The polarization multiplexer / demultiplexer 42A is installed so as to supply P-wave light from the light source 16A to the projection / condensing lens 44A and supply S-wave light from the projection / condensing lens 44A to the light receiver 18A. The

On the other hand, the light source 16B of the optical transceiver 40B outputs S-wave signal light or test light. Polarization demultiplexer 42B supplies the light of S-wave from the light source 16B in the projection-condenser lens 44B, it is disposed the light of P-wave from the projection-condenser lens 44B to supply the light receiver 18B The

  The polarization multiplexer / demultiplexer 42A supplies the output light of the light source 16A to the projection / condensing lens 44A. The projection / condensing lens 44A projects the light from the polarization multiplexer / demultiplexer 42A toward the optical transceiver 40B. The signal light beam output from the optical transmission / reception device 40A is diffused as described above, reaches the optical transmission / reception device 40B, and enters the projection / condensing lens 44B and the light receiver 20B of the optical transmission / reception device 40B. The projection / condensing lens 40B makes the signal light from the optical transceiver 40A incident on the polarization multiplexer / demultiplexer 42B. The polarization multiplexer / demultiplexer 42B supplies the signal light from the optical transceiver 40A to the light receiver 18B according to the polarization. The operations of the light receivers 18B and 20B and the subsequent devices are the same as those in the first embodiment.

  The polarization multiplexer / demultiplexer 42B supplies the output light of the light source 16B to the projection / condensing lens 44B. The projection / condensing lens 44B projects the light from the polarization multiplexer / demultiplexer 42B toward the optical transceiver 40A. The signal light beam output from the optical transmission / reception device 40B diffuses as described above, reaches the optical transmission / reception device 40A, and enters the projection / condensing lens 44BA and the light receiver 20A of the optical transmission / reception device 40A. The projection / condensing lens 40A enters the signal light from the optical transceiver 40B into the polarization multiplexer / demultiplexer 42A. The polarization multiplexer / demultiplexer 42A supplies the signal light from the optical transceiver 40B to the light receiver 18A according to the polarization. The operations of the light receivers 18A, 20A and the subsequent devices are the same as in the first embodiment.

  In the embodiment shown in FIG. 3, projection / condensing lenses 44A and 44B, that is, signal provisional entrances and exits can be arranged at the centers of the light receivers 30A and 20B. Thereby, it can respond similarly to the penetration | invasion of the shield from which direction.

  In the second embodiment, the polarization is varied depending on the transmission direction, but the wavelength may be varied depending on the transmission direction. In that case, instead of the polarization multiplexers / demultiplexers 42A and 42B, wavelength-dependent optical couplers, so-called wavelength division multiplexing (WDM) optical couplers, may be used.

  FIG. 4 shows a schematic block diagram of a fourth embodiment of the present invention. In each of the embodiments described above, the plurality of optical path shielding detection light receivers 20A arranged around the signal receiving light receiver 18A detected leakage of the signal light beam. However, in this embodiment, the signal light beam is cylindrical. A plurality of shielding object detection beams are arranged separately from the signal light beam so as to surround the signal light beam, and the shielding object detection beams are detected by a plurality of light path shielding detection light receivers arranged around the signal receiving light receiver. . Since the signal light beam can be narrowed, the signal-to-noise ratio (SNR) of the signal light is improved and the transmission distance can be extended.

  The optical transmission / reception device 110A transmits data D1 to the optical transmission / reception device 110B via the spatial transmission path 112, and the optical transmission / reception device 110B transmits data D2 to the optical transmission / reception device 110A via the spatial transmission path 112.

  The optical transmission / reception device 110A includes, as optical elements, a signal light source 116A, a signal receiving light receiver 118A, a plurality of light sources 120A that output a shielding object detection beam, and a plurality of light receivers 122A that receive the shielding object detection beam. Similarly, the optical transceiver 110B includes, as optical elements, a signal light source 116B, a light receiving device 118B for signal reception, a plurality of light sources 120B that output a shielding object detection beam, and a plurality of shielding object detection devices that receive the shielding object detection beam. The photoreceiver 122B is provided. The light sources 116A and 120A and the light receivers 118A and 122A of the optical transceiver 110A are disposed so as to face the light receivers 118B and 122B and the light sources 116B and 120B corresponding to the optical transceiver 110B, respectively. That is, the optical receiver 118B receives the output beam of the signal light source 116A. The light receiver 118A for receiving signals receives the output beam of the signal light source 116B. The shielding object detecting light receiver 122A receives the output beam of the facing shielding object detection beam output light source 120B. The light detector 122B for detecting the shielding object receives the output beam of the shielding object detection beam output light source 120A that faces it.

  The shielding object detection beams output from the light sources 120A and 120B and incident on the light receivers 122A and 122B are arranged so as to surround the signal light beams output from the light sources 116A and 116B and input to the light receivers 118B and 118A in a cylindrical shape. . That is, the plurality of light sources 120A and the plurality of light receivers 122A are alternately arranged at substantially equal intervals on a circle having a predetermined radius with the light sources 116A and 118A as the centers. As a result, when the shield 114 enters the space transmission path 112, the shield 114 can be detected before the shield 114 blocks the signal light beam. FIG. 5 is a plan view illustrating an arrangement example of the signal light source 116A, the light receiver 118A, the plurality of light sources 120A, and the plurality of light receivers 122A.

  The communication control device 124A of the optical transmission / reception device 110A applies data D1 input from an external device (not shown) to the buffer 126A, and controls data writing and reading of the buffer 126A. The buffer 126A temporarily stores the data D1 from the communication control device 124A, and applies the stored data D1 to the drive circuit 128A in accordance with a read command from the communication control device 124A or automatically. The drive circuit 128A causes the light source 116A to emit light according to the data D1 from the buffer 126A. Thereby, the light source 116A outputs the signal light beam toward the optical transceiver 110B. This signal light beam is incident on the light receiver 118B of the optical transceiver 110B.

  The communication control device 124B, the buffer 126B, and the drive circuit 128B of the optical transmission / reception device 110B operate in the same manner as the communication control device 124A, the buffer 126A, and the drive circuit 128A of the optical transmission / reception device 110A. The signal light beam output from the light source 116B is incident on the light receiver 118A of the optical transceiver 110A.

  The signal identification device 130A identifies the data D2 from the output signal of the light receiver 118A, and applies the identified data D2 to the communication control device 124A. Similarly, the signal identification device 130B identifies the data D1 from the output signal of the light receiver 118B, and applies the identified data D1 to the communication control device 124B.

  The drive circuit 132A drives the light source 120A in pulses or DC, and the drive circuit 132B drives the light source 120B in pulses or DC. The light receiver 122B of the optical transceiver 110B receives the output beam of one light source 120A facing the optical transceiver 110A. Similarly, the optical receiver 122A of the optical transceiver 110A receives the output beam of one light source 120B facing the optical transceiver 110B. Each optical path block identification device 134A identifies whether or not the shielding object 114 has entered the spatial transmission path 112 from the output level of the corresponding light receiver 122A, and applies the identification result to the communication control device 124A. Similarly, each optical path interruption identifying device 134B identifies whether or not the shield 114 has entered the spatial transmission path 112 from the output level of the corresponding light receiver 122B, and applies the identification result to the communication control device 124B. The operation of the communication control devices 124A and 124B when the optical path blocking identification devices 134A and 134B detect the intrusion of the shielding object 114 will be described in detail later.

  First, transmission of data D1 from the optical transceiver 110A to the optical transceiver 110B will be described. The communication control device 124A applies data D1 input from an external device (not shown) to the buffer 126A. When the communication control device 124A does not detect the shielding object 114 in the spatial transmission path 112, the communication control device 124A simply uses the buffer 126A for rate adjustment. Data D1 read from the buffer 126A according to the transmission rate on the spatial transmission path 112 is applied to the drive circuit 128A. The drive circuit 128A drives the light source 116A according to the data D1 from the buffer 126A to emit light. As a result, the light source 116A outputs a signal light beam carrying the data D1 toward the light receiver 118B of the optical transceiver 110B. The light receiver 118B of the optical transceiver 110B converts the signal light from the light source 116A of the optical transceiver 110A into an electrical signal. The signal identification device 130B identifies the data D1 from the electrical signal output from the light receiver 118B. If there is no transmission error, the signal identification device 130B outputs data D1.

  Similarly, the light source 116B of the optical transceiver 110B emits signal light that carries the data D2 toward the light receiver 118A of the optical transceiver 110A. The optical receiver 118A of the optical transceiver 110A converts the signal light from the light source 116B of the optical transceiver 110B into an electrical signal. The signal identification device 130A identifies the data D2 from the output electrical signal of the light receiver 118A. If there is no transmission error, signal identification device 130A outputs data D2.

  It is assumed that the shield 114 blocks any shield detection beam between the light sources 120A and 120B and the light receivers 122A and 122B. At this time, the output level of the light receiver that receives the shielding object detection beam shielded by the shielding object 114 decreases. For example, it is assumed that the light reception level of any one of the light receivers 122A is lowered. Then, the optical path blocking identification device 134A corresponding to the light receiver 122A notifies the communication control device 124A of the detection of the shielding object. When the communication control device 124A receives the shielding object detection notification from any of the optical path shielding identification devices 134A, the communication control device 124A stops reading data from the buffer 126A until it receives notification of the absence of the shielding object from all the optical path shielding identification devices 134A. . As a result, the light source 116A does not output the signal light beam. That is, data transmission from the optical transceiver 110A to the optical transceiver 110B is temporarily stopped.

  When the signal light output from the light source 116A of the optical transceiver 110A is temporarily stopped, the output level of the light receiver 118B is lowered in the optical transceiver 110B. As a result, the communication control device 124B of the optical transmission / reception device 110B can know that the optical transmission / reception device 110A has temporarily stopped data transmission, and in response, temporarily transmits data D2 toward the optical transmission / reception device 110A. Stop. The communication control device 124B waits for the data transmission / reception device 110A to resume data transmission.

  Of course, when the communication control device 124B receives the shielding object detection notification from any of the optical path shielding identification devices 134A prior to the temporary stop of the data transmission of the optical transmission / reception device 110A, the absence of the shielding object from all the optical path shielding identification devices 134A. Until the notification is received, the data reading from the buffer 126B is stopped. That is, the optical transmission / reception device 110B temporarily stops transmission of the data D2 to the optical transmission / reception device 110A.

  The communication control device 124A resumes data transmission when the output of the all-optical path shielding identification device 134A indicates the absence of the shielding object. That is, the communication control device 124A resumes reading the data D1 from the buffer 126A. The drive circuit 128A drives the light source 116A according to the data D1 from the buffer 126A. The light source 116A outputs the signal light that carries the data D1 to the optical transceiver 110B.

  The light receiver 118B of the optical transceiver 110B receives the signal light from the light source 116A, and the signal identification device 130B identifies the data D1 from the output signal of the light receiver 118B, and supplies the received data D1 to the communication control device 124B. . Thereby, the optical transmission / reception device 110B can know the resumption of data transmission of the optical transmission / reception device 110A. In response to the resumption of transmission, the communication control device 124B of the optical transmission / reception device 110B confirms whether or not the output of the all-optical path shielding identification device 134B indicates the absence of the shielding object. The communication control device 124B does not resume the transmission of the data D2 when the output of any one of the light path shielding identification devices 134B indicates the detection of the shielding object. When the output of the all-optical path shielding identification device 134B indicates the absence of the shielding object, the communication control immediate cover 124B resumes transmission of the data D2 to the optical transmission / reception device 110A.

  In the embodiment shown in FIG. 4, as in the embodiment shown in FIG. 3, by adding polarization multiplexers / demultiplexers 42A and 42B or wavelength filters, the signal light beam from the optical transceiver 110A to the optical transceiver 110B is added. The signal light beam from the optical transceiver 110B to the optical transceiver 110A can be arranged on the same optical path in the spatial transmission path 112. This facilitates optical axis adjustment.

  Although the invention has been described with reference to specific illustrative embodiments, various modifications and alterations may be made to the above-described embodiments without departing from the scope of the invention as defined in the claims. This is obvious to an engineer in the field to which the present invention belongs, and such changes and modifications are also included in the technical scope of the present invention.

It is a schematic block diagram of the first embodiment of the present invention. It is a top view which shows the example of arrangement | positioning of 16 A of light sources, light receiver 18A, and light receiver 20A. It is a schematic block diagram of the second embodiment of the present invention. It is a schematic block diagram of the fourth embodiment of the present invention. It is a top view which shows the example of arrangement | positioning of the light source 116A, the light receiver 118A, the light source 120A, and the light receiver 122A.

Explanation of symbols

10A, 10B: Optical transceiver 12: Spatial transmission line 14: Shield 16A, 16B: Light sources 18A, 18B: Light receivers 20A, 20B: Light receivers 22A, 22B: Communication controllers 24A, 24B: Buffers 26A, 26B: Drives Circuits 28A, 28B: Signal identification devices 30A, 30B: Optical path interruption identification devices 40A, 40B: Optical transmission / reception devices 42A, 42B:
42A, 42B: Polarization multiplexers / demultiplexers 44A, 44B: Projection / condensing lenses 110A, 110B: Optical transmission / reception device 112: Spatial transmission path 114: Shields 116A, 116B: Signal light sources 118A, 118B: Light reception for signal reception Units 120A and 120B: Light sources 122A and 122B that output a shielding object detection beam. Light receivers 124A and 124B that receive the shielding object detection beam. Communication control devices 126A and 126B: Buffers 128A and 128B: Drive circuits 130A and 130B: Signal identification Devices 132A and 132B: Drive circuits 134A and 134B: Optical path interruption identification device

Claims (9)

An optical wireless transmission system that transmits and receives signals between a first optical transceiver and a second optical transceiver via a spatial transmission path,
The first optical transceiver (10A, 40A, 110A)
A first signal light generator (16A, 26A; 116A, 128A) for generating a first signal light directed to the second optical transceiver (10B, 40B, 110B);
A first receiver for receiving light (18A, 28A; 118A, 130A) for receiving the second signal light from the second optical transceiver (10B, 40B, 110B);
The second receiving light (18A, 28A; 118A, 130A) is arranged around the first receiving light receiver (18A, 28A; 118A, 130A), and the second signal light is input to the first receiving light receiver (18A, 28A; 118A, 130A). A plurality of first shield detectors (20A, 20A, 14A) that detect a shield (14, 114) that disturbs the input before disturbing the input to the first receiver (18A, 28A; 118A, 130A). 30A; 122A, 134A), and
According to the detection outputs of the plurality of first shield detectors (20A, 30A, 122A, 134A), the output of any of the first shield detectors (20A, 30A; 120A, 134A) is the shield ( 14, 114), the first communication control device (22A) that temporarily stops the output of the first signal light from the first signal light generator (16A, 26A; 116A, 128A) , 124A)
And
The second optical transceiver (10B, 40B, 110B)
A second signal light generator (16B, 26B; 116B, 128B) for generating the second signal light;
A second receiver for receiving light (18B, 28B; 118B, 130B) for receiving the first signal light from the first optical transceiver (10A, 40A, 110A);
The first optical transceiver (10A, 110A) in accordance with the transmission stop of the first signal light, those second signal light generator (16B, 26B; 116B, 128B ) said second signal light from Communication control device (22B, 124B) for temporarily stopping output
An optical wireless transmission system comprising: The second optical transceiver (10B, 40B, 110B) further includes
The second signal receiver (18B, 28B; 118B, 130B) is disposed around the second signal receiver (18B, 28B; 118B, 130B), and the first signal light is input to the second signal receiver (18B, 28B; 118B, 130B). A plurality of second shield detectors (20B, 30B) that detect a shield (14, 114) that disturbs the input before disturbing the input to the second receiver (18B, 28B; 118B, 130B). 122B, 134B)
And
The second communication control device (22B, 124B), according to the detection output of the plurality of second shield detectors (20B, 30B, 122B, 134B), any second shield detector (20B). , 30B; 120B, 134B) indicates the presence of the shield (14, 114), the second signal light from the second signal light generator (16B, 26B; 116B, 128B). The optical wireless transmission system according to claim 1, wherein the output is temporarily stopped. An optical wireless transmission system that transmits and receives signals between a first optical transceiver and a second optical transceiver via a spatial transmission path,
The first optical transceiver (10A, 40A, 110A)
A first signal light generator (16A, 26A; 116A, 128A) for generating a first signal light directed to the second optical transceiver (10B, 40B, 110B);
A first receiver for receiving light (18A, 28A; 118A, 130A) for receiving the second signal light from the second optical transceiver (10B, 40B, 110B);
The first receiving light receiver (18A, 28A; 118A, 130A) is disposed around the first receiving light receiver (18A, 28A; 118A, 130A), and the second signal light is input to the first receiving light receiver (18A, 28A; 118A, 130A). A plurality of first shield detectors (20A, 30A) that detect a shield (14, 114) that interferes with the signal before disturbing the input to the first receiver (18A, 28A; 118A, 130A). 122A, 134A);
According to the detection outputs of the plurality of first shield detectors (20A, 30A, 122A, 134A), the output of any of the first shield detectors (20A, 30A; 120A, 134A) is the shield ( 14, 114), the first communication control device (22A) that temporarily stops the output of the first signal light from the first signal light generator (16A, 26A; 116A, 128A) , 124A)
And
The second optical transceiver (10B, 40B.110B)
A second signal light generator (16B, 26B; 116B, 128B) for generating the second signal light;
A second receiver for receiving light (18B, 28B; 118B, 130B) that receives the first signal light from the first optical transceiver (10A, 40A, 110A);
The second signal receiver (18B, 28B; 118B, 130B) is disposed around the second signal receiver (18B, 28B; 118B, 130B), and the first signal light is input to the second signal receiver (18B, 28B; 118B, 130B). A plurality of second shield detectors (20B, 30B) that detect a shield (14, 114) that disturbs the input before disturbing the input to the second receiver (18B, 28B; 118B, 130B). 122B, 134B);
According to the detection outputs of the plurality of second shield detectors (20B, 30B, 122B, 134B), the output of any of the second shield detectors (20B, 30B; 120B, 134B) is the shield ( 14 and 114), the second communication control device (22B) that temporarily stops the output of the second signal light from the second signal light generator (16B, 26B; 116B, 128B). , 124B)
An optical wireless transmission system comprising: The first optical transceiver (10A, 40A, 110A) further includes a first buffer (24A, 126A) for temporarily storing first data to be transmitted by the first optical transceiver (10B, 110B). The first signal light generator (16A, 26A; 116A, 128A) includes the first data according to the first data read from the first buffer (24A, 126A). Outputting the first signal light to be conveyed;
The second optical transceiver (10B, 110B) further includes a second buffer (24B, 126B) for temporarily storing second data to be transmitted to the first optical transceiver (10A, 110A). Then, the second signal light generator (16B, 26B; 116B, 128B) carries the second data according to the second data read from the second buffer (24B, 126B). The optical wireless transmission system according to any one of claims 1 to 3, wherein the second signal light is output. 4. The optical wireless transmission system according to claim 1, wherein the first shield detector includes a light receiver (20 </ b> A) that receives leakage of the second signal light. 5. The optical wireless transmission system according to claim 3, wherein the second shielding object detector includes a light receiver (20B) that receives leakage of the first signal light. The first optical transceiver (110A) outputs a plurality of first obstacles that output a first shielding object detection beam that spatially surrounds the first and second signal lights in the spatial transmission path (112). An object detection beam output light source (120A),
6. The optical wireless transmission according to claim 1, wherein the second shielding object detector includes a light receiver (122 </ b> B) that receives the first shielding object detection beam. 7. system. The second optical transceiver (110B) outputs a plurality of second obstacles that output a second shielding object detection beam that spatially surrounds the first and second signal lights in the spatial transmission path (112). An object detection beam output light source (120B),
The optical wireless transmission system according to claim 7, wherein the first shield detector includes a light receiver (122A) that receives the second shield detection beam. The first optical transmitter / receiver (40A) further propagates the first signal light and the second signal light through the same beam position in the opposite directions on the spatial transmission path (12). Optical coupler (42A)
The second optical transmitter / receiver (40B) further propagates the first signal light and the second signal light through the same beam position in the opposite directions on the spatial transmission path (12). The optical wireless transmission system according to claim 1, further comprising: an optical coupler (42 </ b> B).

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