JP3276321B2 - Optical communication device - Google Patents

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. 9, terminals 11 and 12 are, for example, optical transceivers 13a, 13b, 13a and 13b fixed to the ceiling of a building.
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. In addition, the contents of the optical transmission packet and the return optical packet relayed in real time from the partner optical transmitting and receiving apparatus are compared, and if the two match, it is determined that the packet is normal. Determines that a positional shift has occurred, and performs optical axis alignment again by the above method.

[0007]

However, in the above-mentioned conventional optical communication apparatus, when the content of the optical transmission packet and the content of the return optical packet do not coincide with each other more than a predetermined number of times, it is determined that the position is misaligned. Therefore, for example, even when a person passes in front of the light emitting unit or the light receiving unit and interrupts the optical path, they do not match continuously more than a predetermined number of times, so that it is not possible to distinguish between the positional deviation and the optical path interruption. Therefore, conventionally, there is a problem in that scanning for optical axis alignment does not need to be restarted, and scanning for optical axis alignment is started even when the optical path is interrupted.

Further, in the conventional optical communication apparatus, at the time of scanning for optical axis alignment, scanning is performed in which the optical transmission / reception unit having at least the light emitting unit and the light receiving unit is rotated stepwise and then stopped. The light reception level is being measured. However, at the moment when the optical transmission / reception unit stops after the rotation, there is a slight attenuation vibration without mechanically stopping completely. Therefore, in order to prevent an erroneous measurement of the received light level due to the vibration, a margin of 100 ms is taken. , A relatively long time is fixedly set as the waiting time of the light reception level measurement, so that there is a problem that the time for optical axis alignment (search time) is long.

[0009] 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 that can improve usability by performing scanning for optical axis alignment only when necessary.

It is another object of the present invention to provide an optical communication device capable of performing optical axis alignment in a short time.

[0011]

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 light receiving 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 the communication device, a light receiving level detecting circuit for detecting an output light receiving signal level of the light receiving section, a turning means for integrally turning the positions of the light receiving section and the light emitting section based on an external drive signal, and a light receiving level detection Calculating means for calculating a level deviation indicating the deviation of the position of the light spot on the light receiving portion from the center position based on the light receiving level detection signal output from the circuit; and calculating the level deviation based on the level deviation calculated by the calculating means. A driving means for supplying a driving signal to the rotating means so that the absolute value of the level deviation is smaller than a preset threshold value, and a light receiving level fluctuation based on a light receiving level of a light receiving level detecting circuit after the driving by the driving means is completed. Monitoring means for monitoring whether or not a light-receiving level change has occurred, and when the monitoring means detects the occurrence of a light-receiving level change, the light-receiving level detection signal output from the light-receiving level detection circuit is fetched a plurality of times at predetermined time intervals. It has a configuration including first determining means for determining whether or not the received light level fluctuation has been reduced based on the difference between the maximum value and the minimum value among the level detection signals, and a control means. Where the above control
The means is used when it is determined that the received light level fluctuation has subsided.
The first value of the received light level detection signal and the received light level
Of the received light level detection signal acquired before the
When the absolute value of the difference from the second value is equal to or less than the first threshold
Causes the monitoring means to continue the monitoring operation,
Calculate if the absolute value of the difference between the values is greater than the first threshold
Re-calculate the level deviation by means and adjust the optical axis.
Start, and when the first value is smaller than the second threshold,
Restarting the optical scanning by the rotation means to start the optical axis alignment first
It is a means to start over.

According to the present invention, it is determined whether or not the received light level fluctuation has subsided based on the difference between the maximum value and the minimum value among a plurality of received light level detection signals taken when the occurrence of the received light level fluctuation is detected. By capturing the value of the received light level detection signal when it is determined that the level change has subsided, and comparing the captured value with the value of the received light level detection signal before the occurrence of the received light level fluctuation, the cause of the received light level fluctuation can be obtained. Judge, and based on the judgment result,
Since one of the continuation of the monitoring operation by the monitoring unit, the recalculation of the level deviation by the calculation unit, and the optical scanning by the rotation unit is executed, optimal control according to the factor can be performed.

Further, according to the present invention, immediately after the rotation of the light receiving portion and the light emitting portion, the light receiving level detection signal is fetched a plurality of times at predetermined time intervals, and the difference between the maximum value and the minimum value of the plurality of light receiving level detection signals is obtained. It is determined whether or not the received light level fluctuation has subsided based on the above, and only when it is determined that the received light level fluctuation has subsided, the level deviation is calculated by the calculating means. It is not necessary to set the level measurement waiting time (fixed), and the waiting time corresponding to the variation of the mechanism and the aging can be obtained.

[0014]

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

FIG. 1 is a block diagram showing an embodiment of the 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. 9) via a driver 33 and a jack 34 based on the E-T with a twisted pair cable.

Thus, 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 and modulated, and then 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. 9).
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 unit 23 and the light receiving unit 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. .

Next, the operation of the embodiment shown in FIG. 1 will be described in more detail.

The present embodiment is characterized in that the CPU 20 of FIG. 1 executes an operation according to flowcharts of FIGS. 4 to 6 described later. After the optical axis alignment operation described later,
The CPU 20 first measures the light receiving level according to a program stored in the storage unit 22 in advance (Step 101 in FIG. 4). That is, the light receiving signal received by the light receiving unit 24 of FIG. 1 and converted into an electric signal is supplied to a light receiving level detecting circuit 26, and after its level is detected, the CP
The data is converted into digital data by the A / D converter 21 of the U 20 and measured by the CPU 20. The measured value of the light receiving level at this time is assumed to be ADOLD.

Subsequently, the CPU 20 measures the light receiving level in the same manner (step 102 in FIG. 4). The measured value of the light receiving level at this time is assumed to be ADNEW1. Then, CP
U20 is the measured value ADOLD and ADN of the light reception level.
The absolute value of the difference from EW1 is calculated, and it is determined whether or not the calculated value is larger than a predetermined first threshold ADTRH1 (for example, 40 mV) (Step 103 in FIG. 4).
At first, since the measured values ADOLD and ADNEW1 of the light receiving level are respectively equal to each other, a determination result indicating that they are not large is obtained, and the process returns to step 102 again to measure the light receiving level and update the value of ADNEW1.

Thereafter, the CPU 20 updates the measured value ADNEW1 of the received light level and the measured value A of the first received light level.
The absolute value of the difference from DOLD is calculated, and a comparison is again made whether the calculated value is greater than the first threshold value ADTRH1 (step 103 in FIG. 4). In this manner, the processing of steps 102 and 103 is repeated until the absolute value of the difference between the measured value ADOLD and ADNEW1 of the received light level becomes larger than the first threshold value ADTRH1, and the measured value ADNEW1 of the received light level becomes a certain time. It is updated at intervals.

If it is determined in step 103 that the absolute value of the difference between the measured light level ADOLD and ADNEW1 is larger than the first threshold ADTRH1, the CPU 20 determines that the light level has fluctuated. The A / D conversion value (measured light reception level) of the light reception level detection signal input from the light reception level detection circuit 26 is taken in, for example, three times at 10 ms intervals (step 10 in FIG. 4).
4). FIG. 7 shows an example of a change in the light receiving level. In this case, three light receiving levels at 10 ms intervals shown in FIG.

Subsequently, the CPU 20 obtains a difference between the maximum value and the minimum value among the three measured values of the received light level, and further determines whether or not the difference value is larger than the first threshold value ADTRH1 ( Step 105 in FIG. 4). When the above difference value is larger than ADTRH1, it is determined that the fluctuation of the light receiving level is still large, and the A / D conversion value (light receiving level measurement value) of the light receiving level detection signal is taken in three times at intervals of 10 ms. (Step 104) It is compared whether the difference between the maximum value and the minimum value is greater than ADTRH1 (Step 105).

As described above, the 3 fetched at 10 ms intervals
The difference between the maximum value and the minimum value of the two received light level measurement values is A
If it is greater than DTRH1, steps 104 and 1
05 is repeated, and the difference between the maximum value and the minimum value is ADTR
It is determined that the fluctuation of the light receiving level has stopped at the time when the light receiving level becomes equal to or less than H1. The measured value of the light receiving level at this time is assumed to be ADNEW2.

Next, the CPU 20 determines the above-described measured light receiving level ADNEW2 when the fluctuation of the light receiving level has subsided.
Is compared with the first received light level measurement value ADOLD (step 107 in FIG. 4), and ADOLD and ADNEW are compared.
2 is equal to a second threshold ADTRH2 (for example,
When a comparison result of not more than 40 mV) is obtained, there is no or substantially no displacement, and it is assumed that the light reception level variation factor is due to a person or the like blocking the optical path of the light receiving unit 24. Judgment, the process returns to step 102 without starting scanning for optical axis alignment, and measures the light receiving level again to monitor the fluctuation of the light receiving level, and ADN
Update EW1.

In step 107, the measured light receiving level ADNEW2 and the first measured light receiving level ADO
When a comparison result indicating that the absolute value of the difference from the LD is larger than the second threshold value ADTRH2 is obtained, it is determined that the light reception level variation factor is due to the positional displacement due to the minute movement, and the optical axis is determined. Proceeding to step 111 in FIG. 5 to start the alignment scan, the level deviation dV in both the x and y directions
Calculate x, dVy. That is, the optical axis alignment in this case does not restart scanning from the beginning while monitoring the light. The optical transmitting and receiving unit including the light emitting unit 23 and the light receiving unit 24 so that the level deviations dVx and dVy fall within a predetermined range. Is finely moved, that is, a so-called fine search is performed.

Here, as shown in FIG.
In the case of a four-divided photodetector composed of four divided light receiving areas PD to PD, the level deviation dVx is obtained by (PD light receiving level + PD light receiving level) − (PD light receiving level + PD light receiving level), and the level deviation is obtained. dVy is (PD light receiving level + PD light receiving level) − (PD
(Light receiving level + PD light receiving level).

In step 111, the level deviation dV
After calculating x and dVy, the absolute value | dVx | of the level deviation in the x direction is set to a predetermined threshold value Vox.
It is determined whether the absolute value | dVy | of the level deviation in the y direction is smaller than a preset threshold Voy (step 112 in FIG. 5). First, it is determined whether or not | dVx | ≧ Vox (step 113 in FIG. 5).

When | dVx | ≧ 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 114 in FIG. 5). | DVx | <V
In the case of ox, since the shift in the x direction is smaller than the threshold value Vox, the process proceeds to step 119 described later in FIG. 6 to detect the shift in the y direction.

If it is determined in step 114 that the direction deviating from the previous time is different,
Since the movement step STEPX in the direction was too large, the STEPX was changed to a half value (step 1 in FIG. 5).
15) 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 the process proceeds to step 116 in FIG.
It is determined whether Vx is negative.

When dVx <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 (the light receiving level of D) is controlled by controlling the pan direction motor 28 so that the quadrant photodetector moves to the left by step STEPX (step 11 in FIG. 6).
7) When dVx ≧ 0, the pan direction motor 28 is controlled so that the quadrant photodetector moves rightward by step STEPX in the opposite direction (step 11 in FIG. 6).
8).

Subsequently, the same operation as described above is performed in the y direction. That is, it is determined whether or not | dVy | ≧ Voy (step 119 in FIG. 6), and | dVy | ≧ Vo
In the case of y, since the displacement in the y direction is large, it is determined whether or not the displacement direction is the same as before (step 1 in FIG. 6).
20). When | dVy | <Voy, the deviation in the y direction is smaller than the threshold value Voy, so the process proceeds to step 111 in FIG. 5, and the level deviations dVx and dVy in the x and y directions are calculated again.

If it is determined in step 120 that the direction deviating from the previous time is different, the previous y
Since the movement step STEPY in the direction was too large, the STEPY was changed to half the value (step 1 in FIG. 6).
21) 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, and it is determined whether or not the level deviation dVy in the y direction is negative (step 122 in FIG. 6).

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
The tilt direction motor 29 is controlled such that the quadrant photodetector moves upward by step STEPY so as to be equal to the light receiving level of D (step 12 in FIG. 6).
3) When dVy ≧ 0, the tilt direction motor 29 is controlled such that the quadrant photodetector moves downward by step STEPY in the opposite direction (step 12 in FIG. 6).
4).

When the processing in step 123 or 124 is completed, the CPU 20 then proceeds to step 11 in FIG.
Then, the process proceeds to 1 and the level deviations in the x and y directions are calculated again in order to confirm the result of the previous movement control, and the same operation as described above is repeated.

The absolute value of the level deviation in the x direction |
The light spot is positioned substantially at the center of the quadrant photodetector by the movement control such that dVx | is smaller than the threshold value Vox and the absolute value | dVy | of the level deviation in the y direction is smaller than the threshold value Voy. As a result, the optical axes of the incident light and the light receiving unit 24 can be aligned so that the respective optical axes thereof coincide with each other.
After the optical axis alignment is completed (after the fine search is completed), the process returns from step 112 to step 101 in FIG. 4, and the process is restarted from the beginning.

On the other hand, in the step 107, the measured value AD of the received light level when the fluctuation of the received light level has subsided.
When a comparison result indicating that NEW2 is smaller than a preset third threshold value ADTRH3 (for example, 100 mV) is obtained, the light reception level measurement value ADNEW2 is a noise level, and the light reception level fluctuation factor is cut off. Alternatively, it is determined that the shift is due to a large positional shift, and the process proceeds to step 108 in FIG. 5 to start scanning for optical axis alignment.
Start scanning while monitoring the light. That is, the scanning for optical axis alignment at this time is a search to be restarted from the beginning.

That is, the CPU 20 controls the motor driver 2
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 the optical transmission / reception unit 60 shown in FIG. 3 is rotated in the pan direction ± α and the tilt direction ± θ, so that the light transmission / reception from the optical transmission / reception device can be roughly performed. Search for guide light (Step 10 in FIG. 5)
8, 109).

In the above-described optical scanning, for example, as shown in FIG. 8, scanning is performed within a predetermined range from the start position S in a predetermined order shown in ascending numerical order. In FIG. 8, the vertical axis represents the angle in the vertical plane rotation direction (the angle in the tilt direction), the horizontal axis represents the horizontal plane rotation direction (the angle in the pan direction), and “0” to “0”.
“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 light scanning, the CPU 20 generates a light receiving level detection signal inputted from the light receiving level detecting circuit 26 for detecting the light receiving level of the light received by the light receiving section 24 shown in FIG. The CPU 20 monitors whether or not light is detected based on the detected light.
After setting the moving step STEPX (= Nx) in the direction and the moving step STEPY (= Ny) in the y direction (step 110 in FIG. 5), the light receiving level input from the light receiving section 24 through the light receiving level detecting circuit 26 is set. Based on the detection signal, a level deviation dVx in the x direction and a level deviation dVy in the y direction are obtained by calculation (step 1 in FIG. 5).
11).

Hereinafter, as described above, steps 111 to 111
A process for optical axis alignment is performed by 124. After completing the optical axis alignment for matching the optical axes of the incident light and the light receiving unit 24 (after the search), the process returns from step 112 to step 101 in FIG. 4, and the process is restarted from the beginning. As described above, in this embodiment, based on the difference between the maximum value and the minimum value of the received light level measured within the range of 30 ms, it is determined whether the received light level fluctuation has subsided, and it is determined that the received light level fluctuation has subsided. Judgment of what the fluctuation factor is at the light receiving level, and when the fluctuation factor is interrupted by a person or the like passing through the optical path of the light receiving unit, no operation is performed, and a malfunction of the conventional search restart can be prevented. Even if the cause of the displacement is displacement, by changing the search process for optical axis alignment when the displacement is small and large, unnecessary scanning can be eliminated when the displacement is small. Search time can be reduced.

Next, another embodiment of the present invention will be described. This other embodiment comprises the flowcharts of FIGS. 5 and 6 (that is, step 108 is executed first immediately after the start), and after steps 123 and 124, processing similar to steps 104 and 105 is performed. Is added, and the process returns to step 111 after the process is completed.

That is, in this embodiment, during the search process, immediately after the rotation of the optical transmission / reception unit, the light receiving level detection signal output from the light receiving level detecting circuit 26 is fetched three times at 10 ms intervals, and these three times are received. Judgment is made based on the difference between the maximum value and the minimum value of the received light level detection signal as to whether the received light level fluctuation has subsided, and it is judged that the received light level fluctuation has subsided when the difference between the maximum value and the minimum value is below a predetermined threshold value. Only when this is done, the level deviations dVx and dVy are calculated in step 111 based on the received light level detection signal at the time when the received light level fluctuation has disappeared.

Therefore, according to this embodiment, it is not necessary to set the light receiving level measurement waiting time (fixed) for preventing erroneous measurement due to the vibration of the optical transmitting / receiving unit, and the time required for optical axis alignment (search time). Can be shortened as compared with the related art, and the waiting time can be obtained according to the variation of the mechanism and the aging, so that the search reliability can be improved.

It should be noted that the present invention is not limited to the above embodiment.
When it is determined that W2 <ADTRH3, processing such as sounding a warning sound in parallel with the search processing or to prompt the search processing may be performed.

[0053]

As described above, according to the present invention,
Optimal control according to the light reception level fluctuation factor can be performed. For example, if the difference between the two light reception level measurement values before and after the light reception level fluctuation is the same, the fluctuation factor causes a person or the like to pass through the optical path of the light reception unit. Since no operation is performed by judging that the search has been interrupted, a malfunction of the conventional search restart can be prevented. In addition, when the absolute value of the difference between the two measured light reception levels is larger than the first threshold, the variation factor Is determined to be a small positional deviation, the level deviation is recalculated by the calculation means to start the optical axis alignment, thereby making unnecessary scanning in the optical axis alignment unnecessary, thereby reducing the search time. Can be shortened.

According to the present invention, the level deviation is calculated by the calculating means only when it is determined that the fluctuation of the light receiving level has subsided. Since it is not necessary to set the time (fixed), the time required for optical axis alignment (search time) can be shortened compared to the past,
Since the waiting time corresponding to the variation of the mechanism and the secular change can be obtained, the search reliability can be improved.

[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 flowchart for explaining the operation of the embodiment of FIG. 1 (part 1);

FIG. 5 is a flowchart for explaining the operation of the embodiment of FIG. 1 (part 2);

FIG. 6 is a flowchart for explaining the operation of the embodiment of FIG. 1 (part 3);

FIG. 7 is a diagram illustrating an example of a change in a light reception level and a light reception level taken in an embodiment of the present invention.

FIG. 8 is an explanatory diagram of an example of optical scanning according to the embodiment of FIG. 1;

FIG. 9 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 detection 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

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Motoyasu Nagashima 3-3-3 Toyosu, Koto-ku, Tokyo NTT Data Communication Corporation (72) Inventor Masamichi Sato Toyosu, Koto-ku, Tokyo JP-A-11-95882 (JP, A) JP-A-11-98082 (JP, A) JP-A-11-958-3 98081 (JP, A) JP-A-8-149077 (JP, A) JP-A-7-231301 (JP, A) JP-A 8-223117 (JP, A) JP-A 8-139676 (JP, A) JP-A-9-307502 (JP, A) JP-A-6-265638 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00 -14/08 G06F 3/00

Claims (3)

(57) [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 transmitting / receiving device and the light transmitting / receiving device via the light receiving unit and the light emitting unit after performing optical axis alignment between the light transmitting / receiving unit and the light transmitting / receiving device, the output of the light receiving unit being A light reception level detection circuit for detecting a light reception signal level; a rotation unit for integrally controlling the positions of the light reception unit and the light emission unit based on an external drive signal; and a light reception output from the light reception level detection circuit Based on a level detection signal, calculating means for calculating a level deviation indicating a deviation from the center position of the position of the light spot on the light receiving unit, based on the level deviation calculated by the calculating means, A driving unit that supplies the driving signal to the rotation unit so that an absolute value of the bell deviation is smaller than a preset threshold, based on a light reception level of the light reception level detection circuit after driving by the driving unit is completed. Monitoring means for monitoring whether a light-receiving level change has occurred; and when the monitoring means detects the occurrence of the light-receiving level change, the light-receiving level detection signal output from the light-receiving level detection circuit is repeated a plurality of times at predetermined time intervals. Fetching, first determining means for determining whether or not the received light level fluctuation has subsided based on a difference between a maximum value and a minimum value among the plurality of received light level detection signals, and when it is determined that the received light level fluctuation has subsided. Taking
A first value of the received light level detection signal
The received light level detection acquired before the level fluctuation occurs
The absolute value of the difference between the output signal and the second value is less than or equal to the first threshold.
The monitoring operation by the monitoring means is continued,
Wherein when the absolute value of the difference between the first and second values is larger than the previous SL first threshold to initiate the optical axis alignment made to perform a recalculation of the level difference by the calculation means, the first An optical communication device comprising: a controller that restarts the optical scanning by the rotating unit when the value of the optical axis is smaller than a second threshold value and restarts the optical axis alignment from the beginning. 2. The control means according to claim 1, wherein said first value is equal to said first value .
When less than 2 of the threshold, the optical communication apparatus according to claim 1, wherein the beep. 3. In order to detect the guide light emitted from the optical transmission / reception device, optical scanning for moving a light receiving unit and a light emitting unit is performed while monitoring a light receiving signal from the light receiving unit. An optical communication device that performs optical communication between the light transmitting / receiving device and the light transmitting / receiving device via the light receiving unit and the light emitting unit after performing optical axis alignment between the light transmitting / receiving unit and the light transmitting / receiving device, the output of the light receiving unit being A light reception level detection circuit for detecting a light reception signal level; a rotation unit for integrally controlling the positions of the light reception unit and the light emission unit based on an external drive signal; and a light reception output from the light reception level detection circuit Based on a level detection signal, calculating means for calculating a level deviation indicating a deviation from the center position of the position of the light spot on the light receiving unit, based on the level deviation calculated by the calculating means, Driving means for supplying the driving signal to the rotating means so that the absolute value of the bell deviation is smaller than a preset threshold, and immediately after the rotation of the light receiving unit and the light emitting unit by the rotating means, The received light level detection signal output from the received light level detection circuit is captured a plurality of times at predetermined time intervals, and it is determined whether or not the received light level fluctuation has been reduced based on a difference between a maximum value and a minimum value of the plurality of received light level detection signals, An optical communication apparatus comprising: a second determination unit that causes the calculation unit to calculate the level deviation only when it is determined that the received light level fluctuation has subsided.