JPH1198081A - Optical communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical communication device which performs light axis matching in a short time and performs a follow-up operation to an optical transmitter-receiver. SOLUTION: A light receiving part 24 converges incident light by a receiving side lens and the light is made incident as a light spot on a quarter photodetector. Four output light receiving signals of the quarter photodetector have their levels detected by a light receiving level detection circuit 26 and are inputted to a CPU 20 to calculate level deviations in the both directions of (x) and (y). The CPU 20 performs rotation control of a motor 28 for a pan direction and a motor 29 for a tilt direction so that an absolute value of the level deviations may be threshold that is preliminarily defined or less. A light emitting part 23 and a light receiving part 24 are rotated by the rotations of the motors 28 and 29. With this, because the light spot is positioned at an almost center of the quarter photodetector, it can perform light axis matching with the optical transmitter-receiver that emits light. Also, a follow-up operation to the optical transmitter-receiver due to relative movement can be similarly performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication device,
In particular, the present invention relates to an optical communication device that is connected to a portable terminal and enables the terminal to communicate with a partner terminal by an optical signal.

[0002]

2. Description of the Related Art In recent years, a LAN (local area network) for communicating between terminals such as personal computers, servers, and workstations, which are distributed and installed in relatively small areas such as in the same site or building. Are rapidly spreading. In such a LAN, the terminals as components are loosely coupled to each other so that they can operate independently. Each terminal can be moved for portable use, but if all of the terminals are wired, it is inconvenient to use. A LAN using an optical transmission line as a unit is known.

In a LAN using this optical transmission line, for example, as shown in FIG. 8, terminals 11 and 12 are connected to, for example, optical transceivers 13a, 13b,
13c. Further, the optical transceivers 13a, 13b, 13c are connected to transceivers 14a, 14b, 14c fixed corresponding to the ceiling, respectively. Transceivers 14a, 14b and 14c
Are connected to a server or the like (not shown) via the Ethernet line 15.

The terminal 11 comprises an information processing device 11a such as a personal computer or a printer, and an optical communication device 11b connected to the information processing device 11a by a cable. Similarly, the terminal 12 includes an information processing device 12a and an optical communication device 12b connected thereto by a cable. Each of the optical transmitting / receiving devices 13a to 13c constantly emits a guide light, and when receiving transmission light from the optical communication devices 11b and 12b, optical communication with the optical communication device is enabled. .

The optical communication devices 11b and 12b are controlled by information processing devices 11a and 12a, whereby the information processing devices 11a and 12a are connected to the optical communication devices 11b and 12b connected to the optical communication devices 11b and 12b. Communication is performed between the nearest one of the transmitting and receiving devices 13a, 13b, and 13c, the transceiver connected to the optical transmitting and receiving device, and the partner terminal (not shown) via the Ethernet line 15. It is possible.

In the LAN having such a system configuration, the conventional optical communication devices 11b and 12b have optical transmission / reception devices 13a to 13c which always emit guide light.
Scanning the optical transmitting and receiving unit in a certain range, detecting the maximum position of the optical receiving level within the range, and moving the optical transmitting and receiving unit to the position in order to search for the nearest optical transmitting and receiving device. Thus, the optical axis between the optical transceiver and the optical transceiver is aligned.

[0007]

However, in the above-mentioned conventional optical communication apparatus, the light receiving level (light receiving level) must be measured at all points within a preset scanning range. There is a problem that it takes a long time. Further, since the conventional optical communication device has a configuration in which the light receiving section has a single light receiving area, it is impossible to detect the moving direction even if it is known that the light receiving section has been moved, so that the following operation is impossible.

[0008] The present invention has been made in view of the above points,
An object of the present invention is to provide an optical communication device capable of performing optical axis alignment in a short time.

Another object of the present invention is to provide an optical communication device capable of following an optical transmission / reception device.

[0010]

According to the present invention, in order to achieve the above-mentioned object, an optical scanning moving a light receiving section and a light emitting section is performed by the light receiving section in order to detect the guide light radiated from the optical transceiver. A light that performs while monitoring the received light signal, performs optical axis alignment between the light receiving unit and the light emitting unit and the optical transmitting and receiving device after detecting the guide light, and then performs optical communication with the optical transmitting and receiving device via the light receiving unit and the light emitting unit. In a communication device, a split photodetector used as a light receiving unit and having a light receiving area divided into three or more, a light receiving level detecting circuit for detecting each output light receiving signal level of the split light receiving area of the split photodetector, and Calculating a level deviation in both x and y directions indicating a deviation of the position of the light spot on the divided photodetector from the center position of the divided photodetector based on the received light level detection signal output from the received light level detection circuit. Calculating means, and moving control means for controlling the movement of the positions of the light receiving unit and the light emitting unit based on the level deviation calculated by the calculating unit, such that the absolute value of the level deviation is smaller than a preset threshold. It is configured.

In the present invention, x, which indicates a deviation of the position of the light spot on the split photodetector from the center position of the split photodetector,
Since the positions of the light receiving unit and the light emitting unit are controlled to move so that the absolute value of the level deviation in both y directions is smaller than a preset threshold value, the light is transmitted even when the optical transceiver is fixed or relatively moved. The spot can be made to be substantially at the center position on the split photodetector.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an optical communication apparatus according to the present invention. In this embodiment, the LAN optical communication devices 11b and 12b having the system configuration shown in FIG.
It is a device used as. In FIG. 1, a central processing unit (CPU) 20 includes an A / D conversion unit 21 and a storage unit 2.
2 for controlling each part of the apparatus and supervising the operation of the entire apparatus. At the time of optical axis alignment performed prior to communication, the CPU 20 starts a processing operation described later by pressing the search switch (SW) 32.

The light emitting section 23 operates under the control of the CPU 20, and operates as a large-scale semiconductor integrated circuit (LSI) 25 for optical modulation and demodulation.
The optical signal is subjected to electro-optical conversion of the encoded transmission signal from the optical disc, and an optical signal whose light intensity is modulated by the transmission signal is output. The light receiving unit 24 converts the received light into a received signal that is an electric signal,
The received signal is supplied to an optical modulation / demodulation LSI 25 for demodulation, and is supplied to a light reception level detection circuit 26 to detect a light reception level.

The light emitting section 23 and the light receiving section 24 have a CP
In response to a drive signal input from U20 via a motor driver 27, the respective optical axis positions are controlled to move in the pan direction and the tilt direction by a pan direction motor 28 and a tilt direction motor 29 which are driven independently of each other. . The pan direction limit SW 30 is a switch that is turned on at the limit point of the scanning range of the optical axis of the light emitting unit 23 and the light receiving unit 24 in the pan direction. Similarly, the tilt direction limit SW 31 is
The switch is turned on at the limit of the scanning range of the light emitting unit 23 and the light receiving unit 24 in the tilt direction of the optical axis.

The CPU 20 and the optical modulation / demodulation LSI 25 are 10 BAS which are an example of LAN transmission line specifications standardized by 802.3 of the Institute of Electrical and Electronics Engineers (IEEE) of the United States.
It is connected to an information processing device (not shown) such as a personal computer (11a or 12a in the example of FIG. 8) via a driver 33 and a jack 34 based on the E-T with a twisted pair cable.

In this way, during communication after optical axis alignment, which will be described later, transmission data from the information processing device is supplied to the optical modulation / demodulation LSI 25 via the jack 34 and the driver 33, modulated, and then emitted from the light emitting unit. The signal is converted into an optical signal by 23 and transmitted. On the other hand, the transmission data from the partner terminal is the optical transmission / reception device (13a to 13c in the example of FIG. 8).
After being converted into an optical signal and received by the light receiving unit 24,
The signal is demodulated by the optical modulation / demodulation LSI 25 and further transmitted to the information processing device through the driver 33 and the jack 34.

The mechanism itself of the optical communication apparatus according to the present embodiment having such a block configuration is disclosed by the present applicant in Japanese Patent Application No. 9-784.
No. 67 (Title of Invention "Optical Transceiver")
The optical communication device shown in the plan view of FIG. 2 can be used as it is. In FIG. 2, the center point of the transmitting lens 41 is provided at a position away from the center point of the receiving lens 42 by δ in parallel with the axial direction of the shaft of the motor 29 for tilt direction. Each of the transmitting lens 41 and the receiving lens 42 is an aspherical lens, and can greatly reduce the focal length as compared with a spherical lens. The transmitting lens 41 constitutes the light emitting section 23 together with a light emitting element (not shown) provided at a lower portion in a direction perpendicular to the paper surface. The receiving lens 42 constitutes the light receiving section 24 together with a light receiving element (not shown) provided at a lower portion in a direction perpendicular to the paper surface.

A first shaft 44 supporting an optical transmission / reception unit composed of the light emitting section 23 and the light receiving section 24 is
6 and 47 are rotatably supported. Arms 46, 4
Reference numeral 7 denotes a bifurcated fork-shaped support member together with a back plate 51 supporting one end thereof, and a second shaft 48 as a base shaft extending from the rear surface of the back plate 51 in a direction opposite to the arms 46 and 47. The first bearing 45 is attached to the arms 46 and 47 to support the shaft 44.

The tilt direction motor 29 includes a small-diameter gear (not shown) having a central portion fixed to the motor shaft, a large-diameter gear 52 meshing with the small-diameter gear, and a worm 53 integrally formed with the large-diameter gear 52. , Together with the toothless wheel 54 integrally attached to the first shaft 44, constitutes a first rotation mechanism.

On the other hand, a pan-direction motor 28 (not shown in FIG. 2) has a small-diameter gear 55 whose center is fixed to the motor shaft, a large-diameter gear 56 meshed with the small-diameter gear 55, and a large-diameter gear 56. Worm 5 integrated with
7 and the toothless wheel 58 integrally attached to the second shaft 48 constitute a second rotation mechanism. The second shaft 48 is attached to a second support member 50 via a second bearing 49.

As a result, as shown in the schematic perspective view of FIG. 3, the light transmitting / receiving unit 60 composed of the light emitting section 23 and the light receiving section 24 including the transmitting lens 41 and the receiving lens 42 is provided with a tilt direction motor. Is rotated about the axis 44 in the tilt direction of + θ or −θ in the vertical plane, and is rotated by the pan direction motor in the pan direction of + α or −α in the horizontal plane about the axis 48. .

Here, the light receiving section 24 in the embodiment of the present invention focuses the incident light by the receiving lens 42 and forms it as a light spot, which is a quadrant photodetector (PD) shown in the plan view of FIG. 70. As shown in FIG. 4A, the quadrant photodetector 70 has a well-known configuration including four photodetectors (divided light receiving areas) PD, PD, PD, and PD. In the present embodiment, the optical axis alignment and the tracking operation are performed using the four-divided photodetector 70.

Next, the optical axis alignment and follow-up operation of the embodiment shown in FIG. 1 will be described with reference to FIGS. 4, 5 and 6, and the optical scanning order shown in FIG. FIG.
When the search SW 32 is pressed, the CPU 20 starts the optical axis alignment and following operation by the operation according to FIGS. 5 and 6 according to the program stored in the storage unit 22 in advance. That is, first, the CPU 20
7, a drive signal is supplied to a pan direction motor 28 and a tilt direction motor 29, respectively.
The rotation angles of 8 and 29 are controlled independently of each other, and by rotating the optical transmitting / receiving unit 60 shown in FIG. 3 in the pan direction ± α and the tilt direction ± θ, the light transmitting / receiving Search for guide light (Step 10 in FIG. 5)
1, 102).

The above-described optical scanning scans a predetermined range from a start position S in a predetermined order shown in ascending numerical order, as shown in FIG. 7, for example. 7, the vertical axis indicates the angle in the vertical plane rotation direction (angle in the tilt direction), and the horizontal axis indicates the horizontal plane rotation direction (angle in the pan direction).
“12” indicates scanning in the first scanning range, and “13” to “2”.
“6” indicates scanning in the second scanning range, and “27” to “39” indicate scanning in the third scanning range.

During the above-described optical scanning, the CPU 20 outputs a received light level detection signal input to the A / D converter 21 from a received light level detection circuit 26 for detecting the received light level of the light received by the light receiving section 24 in FIG. The CPU 20 monitors whether or not light is detected based on the detected light.
After setting a moving step STEPX (= Nx) in the direction and a moving step STEPY (= Ny) in the y direction (step 103), a light receiving signal from the light receiving section 24 is obtained.
More specifically, a level deviation dVx in the x direction and a level deviation dVy in the y direction are calculated based on a light reception level detection signal input from the quadrant photodetector 70 in FIG. Ask (Step 10
4).

Here, the level deviation dVx is obtained by (PD light receiving level + PD light receiving level)-(PD light receiving level + PD light receiving level), and level deviation dVy is (PD light receiving level + PD light receiving level)-( PD
(Light receiving level + PD light receiving level).

Subsequently, the absolute value | dVx | of the level deviation in the x direction is smaller than a preset threshold value Vox,
It is determined whether the absolute value | dVx | of the level deviation in the x direction is smaller than a preset threshold value Vox (step 105). Since the light spot is located substantially at the center, the process ends. In other cases, since the light spot is shifted to any one, | dVx | ≧ Vox
Is determined (step 106). | DVx
When | ≧ Vox, since the displacement in the x direction is large, it is determined whether or not the displacement direction is the same as before (step 107). When | dVx | <Vox, the shift in the x direction is smaller than the threshold value Vox, and the process proceeds to step 112 described later in FIG. 6 to detect the shift in the y direction.

If it is determined in step 107 that the direction deviating from the previous time is different,
Since the moving step STEPX in the direction is too large, the STEPX is changed to a half value (step 10).
8) On the other hand, when the direction deviating from the previous time is the same, the above-described movement step STEPX in the x direction is not changed, and
Proceeding to step 109 in FIG. 6, the level deviation dVx in the x direction
It is determined whether is negative.

When dVx <0, (light receiving level of PD + light receiving level of PD) <(light receiving level of PD +
(PD light receiving level), (PD light receiving level + PD light receiving level) is (PD light receiving level + P
4A, the pan direction motor 28 is controlled so that the quadrant photodetector 70 moves leftward in FIG. 4A by step STEPX (step 110), and dVx ≧ 0. In the case of, the pan direction motor 28 is controlled so that the quadrant photodetector 70 moves rightward by step STEPX in the opposite direction (step 1).
11).

Subsequently, the same operation as described above is performed in the y direction. That is, it is determined whether or not | dVy | ≧ Voy (step 112). When | dVy | ≧ Voy, the deviation in the y direction is large, so it is determined whether or not the deviation direction is the same as before (step 113). . | D
When Vy | <Voy, the deviation in the y direction is the threshold value Voy.
Since it is smaller, the process proceeds to step 104 in FIG.
The level deviations dVx and dVy in the direction are calculated again.

If it is determined in step 113 that the direction deviating from the previous time is different,
Since the moving step STEPY in the direction is too large, the STEPY is changed to a half value (step 11).
4) On the other hand, when the direction deviating from the previous time is the same, the above-described movement step STEPY in the y direction is not changed.
It is determined whether the level deviation dVy in the y direction is negative (step 115).

When dVy <0, (PD light receiving level + PD light receiving level) <(PD light receiving level +
(PD light receiving level), (PD light receiving level + PD light receiving level) is (PD light receiving level + P
D (light receiving level D), the tilt direction motor 29 is controlled so that the quadrant photodetector 70 moves upward in FIG. 4A by step STEPY (step 116), and dVy ≧ 0. In the case of, the tilt direction motor 29 is controlled such that the quadrant photodetector 70 moves downward by step STEPY in the opposite direction (step 117).

When the processing of step 116 or 117 is completed, the CPU 20 then proceeds to step 10 of FIG.
Proceeding to 4, the level deviations in the x and y directions are calculated again to confirm the result of the previous movement control, and the same operation as above is repeated.

Thus, for example, when a light spot exists at the position indicated by 71 in FIG. 4B on the four-divided photodetector 70, the absolute value | dVx | of the level deviation in the x direction is smaller than the threshold value Vox. And the movement control such that the absolute value | dVy | of the level deviation in the y direction becomes smaller than the threshold value Voy, as shown by 72 in FIG.
It will be located almost at the center of the quadrant photodetector 70,
The optical axis can be adjusted by matching the respective optical axes of the light transmitting / receiving device that emits the guide light and the light receiving unit 24.

In this case, in this embodiment, since the four-divided photodetector 70 is used, it is possible to detect which position of the light shift position is shifted on the two-dimensional plane. It is not necessary to measure all the light receiving levels, and the time required for optical axis alignment can be shortened as compared with the related art. Incidentally, according to the experimental results of the present inventor, the time required for optical axis alignment, which conventionally required about 30 seconds to 2 minutes, is greatly reduced to about 3 seconds to 20 seconds according to this embodiment. Was completed.

Further, according to this embodiment, even when the light spot on the four-divided photodetector 70 moves from the center position as shown by 73, the dV is obtained by the same processing as described above.
Since the moving direction is known from x and dVy, the absolute value | dVx | of the level deviation in the x direction is smaller than the threshold value Vox,
In addition, the absolute value | dVy |
By performing a movement control smaller than oy on the optical transmitting and receiving unit (the optical transmitting and receiving unit 60 in FIG. 3) including the light emitting unit 23 and the light receiving unit 24, as shown in FIG. A light spot 74 is provided at the center of the split photodetector 70.
Can be quickly followed.

Note that the present invention is not limited to the above-described embodiment, and it is only necessary to find out how much a photodetector to be used is shifted on a two-dimensional plane. Photodetectors can also be used. However, 5
In the case of division or more, calculation becomes troublesome. Therefore, actually, division into four is most desirable.

[0039]

As described above, according to the present invention,
The light receiving unit uses a divided photodetector having three or more divided areas on the light receiving surface, detects which side of the light receiving spot position in the x direction or the y direction is shifted, and detects the light spot on the divided photodetector. Since it can be almost at the center position, the time required for optical axis alignment with the partner optical transmitting / receiving device can be significantly reduced as compared with the conventional case, and when the partner optical transmitting / receiving device relatively moves. Can also cause the optical communication device to follow the partner optical transmitting / receiving device at a higher speed than in the past.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of an optical communication device according to the present invention.

FIG. 2 is a plan view of an example of a mechanism previously proposed by the present applicant that can be used as a mechanism of the optical communication apparatus of FIG. 1;

FIG. 3 is a schematic perspective view illustrating rotation of a light receiving unit and a light emitting unit in the mechanism of FIG. 2;

FIG. 4 is a diagram illustrating a quadrant photodetector used by the apparatus of the present invention and an operation description;

FIG. 5 is a flowchart for explaining the operation of the embodiment of FIG. 1 (part 1);

FIG. 6 is a flowchart for explaining the operation of the embodiment of FIG. 1 (part 2);

FIG. 7 is an explanatory diagram of an example of optical scanning according to the embodiment of FIG. 1;

FIG. 8 is a system configuration diagram of an example of a main part of a LAN system to which the present invention can be applied.

[Explanation of symbols]

 11b, 12b Optical communication device 20 Central processing unit (CPU) 23 Light emitting unit 24 Light receiving unit 25 Modulation / demodulation large-scale semiconductor integrated circuit (LSI) 26 Light receiving level detecting circuit 27 Motor driver 28 Pan direction motor 29 Tilt direction motor 32 Search switch (SW) 41 Transmitting lens 42 Receiving lens 60 Optical transmitting / receiving unit 70 Quadrant photodetector

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masato Nakamura 3-12-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside the Victor Company of Japan (72) Inventor Yasutoshi Sakai 3-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Address: Victor Company of Japan, Ltd. (72) Kentaro Iguchi 3-12-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture No. NTT Data Communication Co., Ltd. (72) Inventor Masamichi Sato 3-3-3 Toyosu, Koto-ku, Tokyo Inside NTT Data Communication Co., Ltd. (72) Inventor Kazuki Yanaka Tokyo NTT Data Communication Co., Ltd., 3-3-3, Toyosu, Koto-ku, Tokyo

Claims (4)

[Claims] 1. An optical scanning device that moves a light receiving unit and a light emitting unit while monitoring a light receiving signal from the light receiving unit in order to detect a guide light emitted from an optical transceiver. An optical communication device that performs optical communication between the light receiving unit and the light emitting unit and the optical transmitting and receiving device through the light receiving unit and the light emitting unit after performing optical axis alignment with the optical transmitting and receiving device, wherein the light receiving unit is used as the light receiving unit. A divided light detector having a light receiving area divided into three or more, a light receiving level detecting circuit for detecting each output light receiving signal level of the divided light receiving area of the divided light detector, and a light receiving level detecting circuit. X, y indicating the deviation of the position of the light spot on the split photodetector from the center position of the split photodetector based on the output light reception level detection signal
Calculating means for calculating the level deviation in both directions, based on the level deviation calculated by the calculating means, the positions of the light receiving unit and the light emitting unit so that the absolute value of the level deviation is smaller than a preset threshold. An optical communication device comprising: movement control means for controlling movement. 2. A moving mechanism for rotating the light receiving section and the light emitting section independently of each other in a pan direction and a tilt direction, and an absolute value of a level deviation calculated by the calculating means. 2. The optical communication apparatus according to claim 1, further comprising: a driving unit that drives and controls the rotating mechanism so as to rotate the light receiving unit and the light emitting unit in a direction smaller than a preset threshold. . 3. The light-receiving device according to claim 1, wherein when the absolute value of the level deviation is larger than a preset threshold value and when a level deviation in a direction different from that in the previous driving control is input, The optical communication device according to claim 2, wherein the rotation amounts of the unit and the light emitting unit are changed and set to values smaller than the previous values. 4. The divided photodetector is a four-divided photodetector comprising first to fourth divided light-receiving areas, and the calculating means includes a first divided light-receiving area of the four-divided photodetector and a first divided light-receiving area. From the sum of the respective light receiving signal levels of the second divided light receiving regions adjacent to the first divided light receiving region in the y direction, the third and third light receiving regions which are adjacent to the first and second divided light receiving regions in the x direction, respectively. A value obtained by subtracting the sum of the respective light receiving signal levels of the four divided light receiving areas is calculated as a level deviation in the x direction, and the first divided light receiving area of the four-divided photodetector and the x direction of the first divided light receiving area are calculated. From the sum of the respective light receiving signal levels of the third divided light receiving area adjacent to the second and fourth divided light receiving areas respectively adjacent to the first and third divided light receiving areas in the y direction. The value obtained by subtracting the sum of the light receiving signal levels is y
The optical communication apparatus according to claim 1, wherein the optical communication apparatus calculates the level deviation in a direction.