JP2009239800A - Communication device and communicating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the amount of information in optical space communication. <P>SOLUTION: A communication device includes a light receiving unit which receives a light beam carrying information, a decoder which reads the information from the light beam, a retroreflector which reflects the light beam, and a response pattern forming unit which determines a response pattern based on the information and forms the response pattern by interrupting a portion of reflected light from the retroreflector. Information can be returned not only by ON/OFF of the reflected light but also by the response pattern, thereby a large amount of information can be communicated by optical space communication. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical space communication technology.

  A retroreflector (eg, a corner cube) is known in which incident light incident from a light source is reflected in the opposite direction by being substantially parallel to the incident light and returning to the direction of the light source. By arranging an optical shutter on the reflective surface side of the retroreflector and controlling on / off of the optical shutter, it is possible to implement optical space communication by placing information on the reflected light.

Listed below are prior art documents that the applicant has learned about optical space communications.
JP 2000-244408 A JP 2001-298420 A JP 2007-163014 A JP-A-6-317757 JP 7-218636 A JP 7-264135 A JP-A-9-080165 JP-A-10-086770

  In order to transmit a large amount of information by optical communication using a retroreflector and an optical shutter, a high-speed shutter operation is required. However, an optical shutter that can operate at a high speed is expensive, and there is a problem that high power is required for the drive unit of the optical shutter.

  As an inexpensive optical shutter, for example, an optical shutter using liquid crystal can be used. However, the operation speed of the liquid crystal is on the order of several tens of ms, and high-speed switching cannot be performed. In optical communication using such an inexpensive optical shutter, it is difficult to transmit and receive a large amount of information.

  A communication apparatus according to the present invention determines a response pattern based on information, a light receiving unit that receives a light beam carrying information, a decoding unit that reads information from the light beam, a retroreflector that reflects the light beam, and a recursive property A response pattern forming unit that forms a response pattern by blocking a part of the reflected light from the reflector.

  The communication system according to the present invention includes a transmission device and a response device. The transmission device includes a light emitting unit that emits a light beam that carries information, a camera, and a light reception pattern analysis unit. The response device includes the configuration of the communication device according to the present invention. The camera captures the reflected light. The light reception pattern analysis unit reads the response pattern from the captured reflected light.

  According to the present invention, information can be put on reflected light not only by turning on / off the optical shutter but also by a response pattern, so that a large amount of information can be communicated by optical space communication.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Example of shooting system]
In a situation where an enemy or ally is confused in an area that is in a battle state, a function for identifying a target (person, vehicle, etc.) and identifying whether it is an enemy or ally is required. In such an operation scene, confidentiality (a question about a target is not detected in the surroundings) is required. If communication is performed using a radio wave medium, directivity is poor and radio waves reflected to the surroundings may be detected by the enemy. Therefore, light with high directivity such as laser light is desirable as the communication medium. In the case of such light, since directivity is high, it is necessary to accurately grasp the direction (location of the interrogation device) in which the target receiving the light returns a signal. Otherwise, the reply light must be emitted at a wide angle, which requires a large amount of power and is also problematic in terms of confidentiality.

  One possible solution to this problem is to use a retroreflector as a response device. The retroreflector has a characteristic of reflecting incident light in a direction in which the light has entered (retroreflection retroreflection). Therefore, by modulating the reflected light and carrying information, it is possible to return a response signal without having to detect the location of the interrogator. In such an optical communication apparatus, it is desired to transmit more information with a cheaper mechanism.

  Referring to FIG. 4, the communication system according to the present embodiment is a shooting system that controls shooting by individually identifying a plurality of vehicles 15. The optical communication system in the present embodiment includes a transmission device 1 and a response device 2. The transmission device 1 is mounted on, for example, a helicopter. The response device 2 is attached to each of the plurality of vehicles 15.

  When a helicopter or the like equipped with the transmission device 1 shoots at the vehicle 15, the transmission device 1 generates a question signal 3 that carries the question information by modulating the laser light, and transmits the question signal 3 to the communication target vehicle 15. .

  The response device 2 decodes the question signal 3 to recognize the question information, generates a predetermined response pattern based on the recognition, and sends the response signal 4 carrying the response pattern in the direction of the light source of the question signal 3. Send back.

  The transmission device 1 receives the response signal 4 and analyzes the response pattern included in the response signal 4. The transmission device authenticates the vehicle 15 based on the result of the analysis. As a result of authentication, if the vehicle 15 recognizes that it is a friend, the helicopter or the like stops shooting.

  This shooting system can be applied to missile seekers. In that case, by irradiating the target with the question signal 3 and analyzing the reflected light, when the missile approaches the target, it can be determined whether the target is an enemy. In the case of an ally, the occurrence of misfiring can be reduced by stopping the fuze operation of the missile.

[Example of carry-out amount management system]
FIG. 5 shows a system for managing the unloading amount of a truck by optical space communication. The response device 2 is attached to each of the plurality of tracks 16. Each response device 2 includes an input device and a storage device. When loading soil or the like on each truck 16, the loading amount is input by the input device and recorded in the storage device.

  The transmission device 1 is installed in equipment on the side that manages the carry-out amount of the truck 16. The transmission device 1 irradiates the target track 16 with the question signal 3. When the response device 2 of the target truck 16 receives the question signal 3, the response device 4 generates a response signal 4 that conveys information on the loading amount by modulating and reflecting the question signal 3 according to the stored loading amount. To send back in the direction of the transmitter 1. The transmission device 1 receives and decodes the response signal 4 and reads information on the load amount. With such communication, the transmission device 1 can grasp the carry-out amount of each truck even when a plurality of trucks are present at a short distance in the carry-out management of earth and sand by the truck.

  FIG. 6 shows an example of the response signal 4 sent back from the response device 2 to the transmission device 1. The optical shutter of the response device 2 has a plurality of sections arranged in a two-dimensional matrix. By controlling these plural sections independently, the response signal 4 has a two-dimensional response pattern formed by the presence or absence of reflected light. In the pattern example P2 in FIG. 6, among the rows of the two-dimensional response pattern, the rows where the reflected light is present in all the sections (between the first row and the second row and between the second row and the third row) , It is treated as a delimiter line that separates the data lines containing the data. Coded data is shown in the first, second, and third lines separated from each other by the separation line. For example, if the section having reflected light is 1 and the section having no reflected light is 0, the first row, the second row, and the third row are continued, and a binary number “011100100101110” is obtained. When loading the earth and sand on the truck 16, if a numerical value indicating the loading amount is input to the input unit of the response device 2, the response device 2 encodes the numerical value according to a predetermined rule, and the response as shown in FIG. 6. The optical shutter is controlled to form a pattern. The transmission device 1 restores a numerical value indicating the load amount by decoding the response pattern of the response signal 4.

[Configuration of communication system]
FIG. 1 shows a configuration of a communication system. The transmission device 1 includes a light emitting unit 1-1, a code signal generating unit 1-2, a camera 1-3, and a light receiving pattern analyzing unit 1-4. The light emitting unit 1-1 wirelessly transmits laser light. The code signal generator 1-2 outputs a light emission code signal to the light emitter 1-1. The camera unit 1-3 captures a camera light reception pattern that is a reflected light pattern of the laser light emitted from the light emitting unit 1-1. The light reception pattern analysis unit 1-4 reads a response pattern, which is information from the response device 2, from the camera light reception pattern captured by the camera unit 1-3, and extracts information included in the response pattern.

  The response device 2 includes a light receiving unit 2-1, a decoding unit 2-2, a response pattern generation control unit 2-3, and a response pattern generation unit 2-4. The light receiving unit 2-1 receives the interrogation signal 3 which is a laser beam emitted from the light emitting unit 1-1 of the response device 1, and converts it into an electrical signal. The decoding unit 2-2 decodes the electric signal generated by the light receiving unit 2-1 in response to the question signal 3, and extracts the question information. The response pattern generation control unit 2-3 determines that the question information obtained by the decoding conforms to a predetermined rule stored in advance and is a legitimate question, determines a response pattern according to the question information, and the response pattern Generate response information that specifies. The response pattern generation unit 2-4 returns the laser beam 3 in the direction of the transmission device 1 by retroreflection. At that time, the response pattern generation unit 2-4 forms a response pattern by blocking a part of the reflected light of the laser beam that carries the interrogation signal 3. As a response pattern, for example, as shown in pattern example P1 in FIG. 1, if the cross pattern is determined as a friend mark, when the transmitting apparatus 1 detects the cross pattern, the target can be identified as the friend.

  FIG. 2 is a cross-sectional view of the response pattern generation unit 2-4 as viewed from the side. The response pattern generation unit 2-4 includes the retroreflective sheet 10. The reflective surface of the retroreflective sheet 10 is disposed on the same side as the light receiving surface of the light receiving unit 2-1. The retroreflective sheet 10 is a two-dimensional retroreflector in which a large number of glass beads 11 are arranged in a matrix on a substrate. The incident laser beam 14 is refracted at the incident surface incident on the glass bead 11 and is reflected by the reflecting surface 12 disposed facing the back side of the glass bead 11. The reflected laser light is refracted at the exit surface when exiting from the glass beads 11, and as a result, the reflected light 4 is reflected in the opposite direction in parallel to the incident light, and is sent back to the light source of the incident light.

  A liquid crystal shutter 13 is disposed on the reflective surface side of the retroreflective sheet 10, that is, on the light source side of incident light. The liquid crystal shutter 13 includes two polarizing plates arranged in parallel and a liquid crystal layer arranged therebetween. The liquid crystal shutter 13 is arranged in a matrix on a surface parallel to the surface of the retroreflective sheet 10, and has a plurality of sections on / off controlled independently. The response pattern generation control unit 2-3 that is a drive unit of the liquid crystal shutter 13 controls the voltage applied to the liquid crystal to change the optical rotation of the liquid crystal in each of the plurality of sections. With this controlled optical rotation, the polarization direction of polarized light that has passed through the first polarizing plate as viewed from the direction in which the light enters is rotated or not rotated. As a result, the light transmittance of the liquid crystal shutter 13 changes and the optical shutter is turned on / off.

  FIG. 3 is a diagram for explaining the communication timing between the transmission device 1 and the response device 2. The horizontal axis indicates the time axis. The transmitting device 1 generates a question signal 3 including a header and a password by transmitting a plurality of laser pulses at a predetermined timing. When the response device 2 receives the header, the response device 2 subsequently receives the password and decodes the password.

  When the reception of the password is completed and the validity of the question signal 3 is authenticated as a result of decoding by the decoding unit 2-2, the response is made during a predetermined time (between time t0 and time t2 in FIG. 3B). The pattern generation control unit 2-3 drives the liquid crystal shutter 13 so as to generate a response pattern stored in advance. The transmission device 1 irradiates the response device 2 with a laser pulse at time t1 between time t0 and time t2. This laser light is sent back as reflected light 4 in the direction of the transmitter 1 by the retroreflective sheet 10. A response pattern is formed on the reflected light 4 by the liquid crystal shutter 13. The camera 1-3 captures the reflected light 4. The light reception pattern analysis unit 1-4 analyzes the photographed reflected light 4 and compares it with a predetermined reference, and outputs an enemy friend determination result.

  The response pattern generation control unit 2-3 can store a plurality of two-dimensional patterns formed sequentially in time series. In this case, when the decoding unit 2-2 authenticates the question signal 3, the liquid crystal shutter 13 is sequentially driven according to the plurality of two-dimensional patterns, and the laser light that bears each of the plurality of two-dimensional patterns as the reflected light 4. Sequentially sent back to the transmitter 1.

Next, effects of the communication system having the above configuration will be described.
By using the retroreflective property on the response side, the following points are effective.
(1) Since an optical medium is used, it is possible to ask questions over a narrow range. This characteristic allows questions to be identified and identified. In addition, since the question signal does not reach in a direction other than the target, confidentiality is high.
(2) Reflection by the retroreflector is not only specular reflection but also recursion in which incident light is reflected in the same direction, so that power saving of the transmitted light can be achieved.
(3) Since the system responds by modulating the reflected light of the retroreflector, the response can be made without detecting the direction in which the response signal should be directed.

  If a communication system having a retroreflective characteristic is realized by one corner cube, there is one communication line. Therefore, for example, in the case of digital communication in which an optical shutter is arranged in front of a retroreflector and response signals are modulated by controlling the presence or absence of reflected light by driving the optical shutter, the operation speed of the optical shutter is the data Higher speed is required as the amount increases.

  As a configuration of such an optical shutter, for example, an optical crystal having an electro-optic effect (hereinafter referred to as an EO crystal) is disposed between two polarizing plates having the same polarization direction, and a voltage applied to the EO crystal. There is a configuration in which light passing through two polarizers is turned on / off by turning on / off. In the case of this method, the EO crystal itself is expensive and the applied voltage becomes a high voltage, so that the size of the EO crystal driving unit is increased.

  In addition, when a liquid crystal is used instead of the EO crystal, an optical shutter can be configured. However, since the operation speed of the liquid crystal is as low as about 30 ms, high-speed reflected light cannot be turned on / off. Therefore, when the one-line digital data transmission as described above is considered, the amount of data that can be transmitted is reduced.

  On the other hand, in the response device 2 of the present embodiment, a retroreflective pattern can be generated two-dimensionally by using a reflector in which the retroreflective sheet 10 and the liquid crystal shutter 13 are combined. Data transmission is possible. Therefore, it is possible to compensate for the disadvantage that the switching time of the liquid crystal is slow and to transmit a larger amount of data.

  As the retroreflector, a retroreflective sheet using glass beads is described in FIG. 3, but instead, a plurality of corner cube-shaped reflective surfaces arranged in a plane may be used. Moreover, although the liquid crystal shutter is described in the drawing as the optical shutter function, this function is a function for controlling the transmission of light and does not specify a material. For example, when the above-mentioned EO crystal is used instead of the liquid crystal shutter 13, the above-described problems can be alleviated by adopting the configuration of the present embodiment.

1 shows a configuration of a communication system. The structure of a response pattern production | generation part is shown. It is a timing chart for demonstrating data transmission / reception. An operation example of the shooting system is shown. An operation example of the carry-out amount management system is shown. An example of transmission data is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission apparatus 1-1 Light emission part 1-2 Code signal generation part 1-3 Camera 1-4 Light reception pattern analysis part 2 Response apparatus 2-1 Light reception part 2-2 Decoding part 2-3 Response pattern generation control part 2-4 Response pattern generator 3 Question signal 4 Reflected light 10 Retroreflective sheet 11 Glass beads 12 Reflecting surface 13 Liquid crystal shutter 14 Laser light 15 Vehicle 16 Tracks P1, P2 Pattern examples

Claims (8)

A light receiving portion for receiving a light beam carrying information;
A decoding unit for reading the information from the light beam;
A retroreflector that reflects the light beam;
A response pattern forming unit that determines a response pattern based on the information and forms the response pattern by blocking a part of the reflected light from the retroreflector. The communication device according to claim 1,
The response pattern forming unit includes:
An optical shutter disposed on the reflective surface side of the retroreflector and having a plurality of sections;
And a control unit that forms the response pattern by independently controlling light transmittance of the plurality of sections based on the information. A communication device according to claim 2, wherein
The communication apparatus, wherein the optical shutter is a liquid crystal shutter. The communication device according to any one of claims 1 to 3,
The said response pattern formation part is a communication apparatus which interrupts | blocks all the reflected light by the said retroreflector, when the said information does not follow the predetermined rule memorize | stored previously. The communication device according to any one of claims 1 to 4,
The response pattern is a plurality of two-dimensional patterns formed sequentially in time series. A communication device according to any one of claims 1 to 5,
Furthermore, an input device is provided,
The said response pattern formation part is a communication apparatus which converts the data input with respect to the said input device into the said response pattern by a predetermined conversion rule. A transmitting device;
A response device;
The transmitter is
A light-emitting unit that emits a light beam carrying information;
A camera,
A light receiving pattern analysis unit,
The response device is:
A light receiving portion for receiving the light beam;
A decoding unit for reading the information from the light beam;
A retroreflector that reflects the light beam;
A response pattern is determined based on the information, and a response pattern forming unit that forms the response pattern by blocking a part of light reflected by the retroreflector,
The camera captures the reflected light;
The light reception pattern analysis unit reads the response pattern from the reflected light that has been photographed. A communication system according to claim 7,
The said light reception pattern analysis part authenticates the target irradiated with the said light ray by collating the said response pattern with the pattern for the comparison memorize | stored previously. The communication system.

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