JPS6359229A - Relay method for space propagation optical communication - Google Patents

Abstract

PURPOSE:To improve the sureness of data transmission by placing a light emitting element to a region opposed to a region of a photodetector in the reception enable state while clipping a center axial line at the signal relay and scanning the element to be in the transmission enable state. CONSTITUTION:When the region P1 is, for example, the photodetecting plane, the region P5 opposed thereto while clipping the center axial line 0 is a light emitting plane. The photodetecting plane is moved, e.g., clockwise as shown in solid line arrow and each region is a light emission plane sequentially in the order of P1-P8. On the other hand, the light emitting plane is moved in the same direction at the same speed as shown in broken line arrow and each region becomes sequentially the photodetecting plane in the order of P5 P6 P7 P8 P1 P2 P3 P4. Thus, the photodetecting plane and the light emitting plane are formed opposite to each other while clipping the center axial line 0 at all times.

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a relay method for communication by spatial optical propagation using light as a carrier wave, and particularly relates to a relay method optimal for spatial propagation optical communication in idle circuits. I'll go.

2. Description of the Related Art In recent years, a space propagation optical communication system has been developed that uses light as a carrier wave to spatially transmit and receive information data. A system is being put into practical use that uses spatial light propagation to communicate with a master station, such as a host computer, located in the same idle station.

Conventionally, in such a space propagation optical communication system using an idle circuit, as shown in FIG.
The repeater 2 is attached to the
Transmission and reception using spatially propagating light is carried out between and the repeater 2,
On the other hand, the repeater 2 and a master station 4 such as a host computer are usually connected by a wire 5 such as an optical fiber or an ordinary electric wire cable, and transmission and reception is performed by non-space transmission via the wire 5. Met. However, in order to actually apply such a system, wiring work is required to connect the repeater 2 and the master station 4 with the wire 5, and when the master station 4 is moved, it is necessary to conduct wiring work again. There is the inconvenience of having to perform wiring replacement work.

Therefore, recently, as shown in FIG.
Systems are being developed that transmit and receive optical signals using space-propagating light not only between G and the repeater 2 but also between the repeater 2 and a master station 4 such as a host computer. According to such a system, there is no need for wiring work, and the master station can also be moved arbitrarily depending on the situation within the station 7, rearrangement, etc.

By the way, the repeater used in the system shown in FIG. It is desirable that both the receiving side (light-receiving side) and the transmitting side (light-emitting side) be non-directional so as to obtain the desired results. However, the light-emitting elements used in this type of communication, such as light-emitting diodes, have strong directivity and are usually effective only within an angular range of about 15 to 20', so they transmit (light-emit) omnidirectionally. In order to achieve this, it is necessary to use a large number of light emitting elements, at least about 40 to 50, to cover the entire area within 7. And if we use a large number of light emitting elements like this,
Even if the current consumption per light emitting element is small, a problem arises in that the current consumption of the repeater as a whole becomes significantly large.

Furthermore, in the system shown in Figure 8, when both the receiving side (light receiving side) and the transmitting side (light emitting side) are made omnidirectional,
In addition to the spatially propagating light from the original terminal equipment being incident on the light receiving element of the repeater, the spatially propagating light emitted from the light emitting element of the repeater itself is also incident due to multiple reflections and diffuse reflections within the repeater. In such cases, the received signal due to the original propagation light may be interfered with by the reflected signal, making it impossible to perform accurate signal relay. Such interference is similar to multipath interference in wireless communications, and will therefore be referred to hereinafter as multipath interference in this specification as well.

Regarding the former of the above two types of problems, that is, the problem of current consumption due to the use of a large number of light emitting elements, a solution has already been proposed in Japanese Patent Laid-Open No. 133744/1983. In this proposed repeater, multiple units that receive and emit light only in a certain range are prepared, and these units can be attached and removed from the repeater's mounting holder in all directions. According to the direction in which the terminal or master station is placed, the light emitting element that is actually used can be mounted only in that direction.
The number of light-receiving elements is reduced to reduce current consumption.

Problems to be Solved by the Invention Although the proposed repeater can solve the problem of current consumption to some extent, multipath interference still remains unsolved. That is, even in the proposed repeater, it was inevitable that the optical signal emitted from the light emitting element of the repeater would enter the light receiving element of the same repeater due to multiple reflections and diffuse reflections.

Furthermore, although the proposed repeater has the effect of reducing current consumption, the current consumption may increase in some cases.

In other words, if there are a large number of terminals and the terminals are located far apart from each other, the number of units that must be attached to the repeater will also increase, and in that case, the current consumption will inevitably increase to some extent. I didn't get it.

In addition, the above-mentioned proposed repeater has the problem that the unit must be attached or removed depending on the arrangement of the terminals and the master station, which requires a lot of effort.

The present invention was made against the background of the above-mentioned circumstances, and relates to a relay method in space propagation optical communication, particularly a relay method in which all transmission and reception between a repeater and other equipment is performed by optical signals using space propagation light. Basically, it is non-directional, and the current consumption can be significantly reduced, and at the same time, the reliability of data transmission can be increased by preventing interference such as multipath interference, and other troublesome work etc. It is an object of the present invention to provide a relay method that does not require the following.

Means for Solving the Problems This invention receives an optical signal based on spatially propagating light transmitted from a device by a light receiving element of a repeater, amplifies it in the repeater, and transmits it in space by a light emitting element of the repeater. In a method for relaying spatial propagation optical communication in which light is transmitted as an optical signal to another device, the repeater is configured to include, around a vertical axis, an inclined outer peripheral surface portion that is inclined with respect to the central axis thereof; The inclined outer circumferential surface is divided into a plurality of regions in the circumferential direction, and a light receiving element and a light emitting element are arranged in each region, and when relaying signals, the light receiving elements are set in a state where each region can receive data. , and the light emitting element is scanned in such a way that it is always in a transmittable state in an area located on the opposite side of the central axis with respect to the area of the light receiving element that is in a receivable state. It is necessary.

Function: In the relay method of the present invention, the relay is installed, for example, on a downward ceiling. Spatial propagation light as an optical signal transmitted from a wave device such as a terminal device is incident on the region (or adjacent region) of each region of the inclined outer surface of the repeater facing the direction of the device. . The light-receiving element is scanned so that each area becomes ready for reception, so when the light-receiving element in the area into which the optical signal from the device is incident becomes ready to receive, the optical signal is electrically transmitted by the light-receiving element in that area. It is converted into a signal and taken into the repeater. The signals captured in this way are subjected to demodulation, modulation, signal interpolation, amplification, waveform shaping, etc. in accordance with the signal modulation method in the repeater, and then spatial propagation from the repeater's light emitting element. It is transmitted as an optical signal using light. Since the light emitting elements are also scanned in each area so as to be in a transmittable state, optical signals as transmission signals are also sequentially transmitted from the light emitting elements in each area. No matter which direction the receiving device, such as a host computer, is located with respect to the repeater, the light emitting elements in each area are sequentially scanned as described above, so that the light emitting elements in any area can be The transmitted optical signal is always received by the light receiving section of the receiving device.

Here, the scanning phase of the light receiving element and the light emitting element is adjusted so that the area of the light receiving element that is ready for reception and the area of the light emitting element that is ready for transmission are always located on opposite sides of the central axis. is shifted by 180°. This means that the light-receiving elements in the area to which the light-emitting element to which the optical signal is currently being transmitted from the repeater and its surrounding areas are not ready for reception, and the light-receiving element in the area where the light-emitting element to which the optical signal is being transmitted is bent. This means that only the light-receiving element on the opposite side of the area is in a receivable state, so the optical signal emitted from that light-emitting element is reflected downward by multiple reflections and diffused reflection, and reaches the light-receiving element in a receivable state. There is little risk of it entering the
Therefore, the possibility that signal transmission accuracy will deteriorate due to multipath interference is significantly reduced.

Furthermore, as is clear from the above, not only the light-receiving elements but also the light-emitting elements are not all enabled for transmission at the same time, but are scanned so that each area is sequentially enabled for transmission. The light-emitting elements that are in operation are only a small part of the total number of light-emitting elements, and therefore the current consumption is much lower than when all the light-emitting elements are driven at the same time.

Embodiments Hereinafter, embodiments of the relay method of the present invention will be described with reference to FIGS. 1 to 6.

1 and 2 show an example of the external appearance of the repeater 2. In this example, the inclined outer peripheral surface portion 6 that is inclined by a predetermined angle O with respect to the vertical central axis O of the repeater 2 is It is divided into eight regions P1 to P8 at equal intervals in the direction. Each area P1 to P8 has three light emitting diodes (hereinafter referred to as "LED") as light emitting elements>7
a, 7b, 7c, and one photodiode (hereinafter referred to as "PD") 8 as a light receiving element. Here, three LEDs 7a to 7G in each area P1 to P8
are installed at slightly different angles from each other.

P belonging to each area P1 to P8 when relaying an optical signal using spatially propagating light using such a repeater 2
D. An example of the operating state of the LED is shown in FIG. In FIG. 3, a white area surrounded by a solid line indicates an area where the LED is in a transmittable state, and hereinafter the area where the LED is in a transmittable state, that is, a light emitting state is referred to as a light emitting surface. In addition, in FIG. 3, the area with crossed diagonal lines indicates the area where the PD is in a receivable state.Hereinafter, we will refer to the area where the PD is in a receivable state, that is, in a state where it can receive an optical signal and take in the signal. It is called the light receiving surface.

As shown in FIG. 3, for example, when the region Pl is the light-receiving surface, the region P5 on the opposite side of the center @ line O with respect to the region P1 is the light-emitting surface. For example, the light-receiving surface moves clockwise as shown by the solid arrow in FIG.
From the state in Figure 3, P1 → P2 → P3 → P4 → P5 → P6
Each region becomes a light emitting surface in the order of →P7→P8. On the other hand, the light emitting surface also moves in the same direction (clockwise in the illustrated example) and at the same speed as indicated by the broken line arrow in FIG. 3, and from the state shown in FIG. →P3→P
Each region becomes a light-receiving surface in the order of 4. Therefore, the regions on opposite sides of the central axis O are always the light-receiving surface and the light-emitting surface.

In the example shown in Fig. 3, the number of regions that simultaneously serve as light-emitting surfaces at a certain time is one region, and the number of regions that serve as light-emitting surfaces is one region, but in some cases there may be two or three regions. may also serve as a light-receiving surface or a light-emitting surface. FIG. 4 shows an example in which two regions simultaneously serve as light-receiving surfaces and two regions serve as light-emitting surfaces. In this case, for example, Pl
, P2 area (Pi + Pe
) is the light emitting surface, and from that state the light receiving surface is (P
I +P2 ) → (P2 +P3 ) → (P3 +P4
)→(P4 +Ps)→(Ps+P8)→(P
a 10P7) → (P7 +Pa) → (Pa 10Pt)
→(Pt+P2), and the light emitting surface also moves in the same way. Of course, the number of regions that simultaneously serve as light-receiving surfaces does not necessarily have to match the number of regions that simultaneously serve as light-emitting surfaces.

FIG. 5 shows a block diagram of an example of the circuit configuration of a repeater used in the method of the present invention.

In FIG. 5, eight receiving circuit units 91 to 98 correspond to each region ij/J and PD of P1 to P8, respectively.
From 8 onwards, when an optical signal from a device, for example an optical signal that has been CMI modulated with information data to be transmitted, is input to the PD corresponding to each unit, the optical signal is converted into an electrical signal and the data is obtained. A signal and a reception detection signal indicating that an optical signal has been input are output. The reception detection signal is sent to the reception unit determination circuit 10, which determines in which reception circuit unit 91 to 98 the optical signal was received, or in other words, to which region P1 to P8 the optical signal was incident, and the result is determined. It is given to the system controller 11. On the other hand, one of the receiving circuit units 91 to 98
The data signal output from the switch circuits 121 to 1
The signal is sent to the demodulator 13 via 28. Switch circuit 121
128 are directly controlled on and off by the switch control circuit 14, and the switch control circuit 14 is instructed by information from the system controller 11 which of the switch circuits 121 to 128 to turn on or off. The demodulator 13 not only demodulates the CMI-modulated data signal, but also performs signal interpolation and error correction, and its operation is controlled by signals from the system controller 11. The demodulated output signal of the demodulator 13 is input to the modulator 15, where it is CMI-modulated again. The modulated signals are provided to transmitting circuit units 161-168. These transmitting circuit units 161 to 168 are for causing the LEDs 7a to 7C in the respective regions P1 to P8 to emit light in accordance with the data signal from the modulator 15, and transmitting optical signals as spatially propagated light. , these transmitting circuit units 161 to 168 are sequentially scan-controlled in an order specified by a control signal from the transmitting unit control circuit 17 so as to be in a transmittable state (light emitting state).

In the circuit configuration shown in FIG. 5 as described above, the switch circuits 121 to 128 are connected to the receiving circuit units in the area located on the opposite side to the area corresponding to the transmitting circuit units 161 to 168 in the transmitting enabled state (light emitting state). It is controlled by the switch control circuit 14 to take in only the data signals from 91-98. For example, when the transmitting circuit unit 165 in the area P5 is in a transmittable state, only the switch circuit 121 of the output path of the receiving circuit unit 91 in the area P1 on the opposite side to the area 11Ps is turned on, and Only the data from the optical signal incident on the PD is taken in, while the other switch circuits 122~
Since 128 is in the off state, the receiving circuit units 92 to 9 receive optical signals incident on the PDs in areas P2 to P8.
8 data output signals are not accepted. As the transmission enabled states of the transmitting circuit units 1 to 161 to ]68 are sequentially scanned, the ON states of the switch circuits 121 to 128 are scanned. Only the data signals from the receiving circuit units 91 to 98 in the area on the opposite side are always taken in. In this way, the state in which the switch circuit of the output path of the receiving circuit unit in a certain area is in the on state corresponds to the reception enabled state for the PD in that area.

As described above, according to the circuit configuration shown in FIG. 5, it is possible to receive and transmit optical signals, that is, to relay optical signals, using the scanning method shown in FIG.

In addition, in the explanation regarding FIG. 5 of (above) E, when the number of areas that are simultaneously in a receiving state and the number of areas that are simultaneously in a transmitting state are both 1, that is, at the same time, the light-receiving surface,
Although we have explained the case where the number of regions that serve as light-emitting surfaces is both 1, it is also possible to maintain the same circuit configuration as shown in Figure 5 and set the number of regions that serve as light-receiving and light-emitting surfaces at the same time as desired by setting the system controller 11. can be changed to .

The scanning speed can also be changed arbitrarily by setting in the system controller 11, but generally one signal @ (1 bit signal @) is sent from an arbitrary position until the entire area is scanned. In order to reliably transmit and receive data, it is desirable to scan at a frequency equal to or higher than the frequency of the original signal bit multiplied by several times the number of divided regions, for example, 2 to 3 times. In other words, when the area is divided into eight areas as described above, one signal is transmitted or received by scanning all eight areas, so at least one signal is transmitted or received during one bit of the original signal. It is necessary for eight areas to be scanned, and in order to increase the reliability and reliability of data transmission and reception, a scanning frequency that is roughly several times higher than that is required, and in the end, the area division is different from the original bit frequency. A scanning frequency that is about 2 to 3 times higher is required.

In addition, in the example of FIGS. 1 to 4, the inclined outer peripheral surface portion 6 of the repeater 2
Although we have shown an example in which the area is divided into 8 areas P1 to P8, it goes without saying that the number of area divisions is not limited to 8. For example, as shown in FIG. You may do so. In this case as well, the number of areas that serve as light-receiving surfaces at the same time,
The number of regions that simultaneously serve as light emitting surfaces is not limited to one, but may be about two to four.

In addition, in the above examples, it was assumed that scanning is performed so that adjacent chain acids become ready for reception, and sequentially adjacent areas become ready for transmission, but in some cases, some Scanning may be performed while skipping areas. For example, when the number of area divisions is eight as shown in FIG. 2, scanning may be performed while skipping two areas. In this case, if the area is scanned clockwise from the area Pl in FIG. 2, the area in which reception is possible is from P1 to P4
The scanning is performed in the order of →P7→P2→P5→P8→P3→P6→P1. Of course, the area that becomes ready for transmission is scanned so as to be the area on the opposite side to the area that is ready for reception. For example, in the above example, P5 → P8 → P3
The scanning is performed in the order of →P6 →P1 →P4 →P7 →P2 →P5.

In addition, in the examples shown in Figures 1 and 2, three LEDs are placed in one area.
7a to 7G @ provided, but LE placed in one area
The number of D can be arbitrarily determined as necessary. Roughly speaking, in the examples shown in FIGS. 1 and 2, each of the regions P1 to P8 into which the inclined outer circumferential surface portion 6 is divided is an inclined plane, but depending on the case, it may be a curved surface, and in that case, the entire inclined outer circumferential surface portion 6 may be part of a continuous spherical surface. When the inclined outer circumferential surface portion 6 is made part of a continuous spherical surface in this way, each of the regions P1 to P8 divided in the circumferential direction also becomes a part of the same spherical surface, so that there are no boundaries between the regions in terms of appearance. It will not be possible.

Effects of the Invention As is clear from the above explanation, according to the relay method of the present invention, an optical signal based on spatially propagating light transmitted from a device is received by a light receiving element of a repeater, and this is amplified within the repeater. When transmitting spatially propagated light as an optical signal to other equipment using the light emitting element of the repeater, the reception and transmission are basically omnidirectional regardless of the position of the transmitting and receiving equipment. However, the number of light-emitting elements that are in the transmitting state (light-emitting state) at the same time is significantly smaller than that of all light-emitting elements, so power consumption is extremely low, and the light emitting state of the repeater is extremely low. There is little risk that the optical signal transmitted from the system will be received by the light-receiving element of the same repeater due to multiple reflections or diffuse reflections in the downward direction, and therefore there is a high possibility that the original received signal will be interfered with by the signal due to the reflection. few. Therefore, according to the relay method of the present invention, it is possible to perform non-directional middle curtain using the free space optical propagation method without using wires at low running cost and with high signal transmission accuracy.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of the external appearance of a repeater used in the relay method of the present invention, FIG. 2 is a bottom view of the repeater shown in FIG. 1, and FIG. FIG. 4 is a schematic diagram showing another example of the scanning situation of the repeater shown in FIGS. 1 and 2, and FIG. 5 is a schematic diagram showing an example of the scanning situation of the repeater shown in FIG. A block diagram showing the electrical circuit configuration of a repeater used in the method, FIG. 6 is a bottom view showing another example of a repeater used in the relay method of the present invention, and FIG. An explanatory diagram showing an example, FIG. 8 is an explanatory diagram showing a conventional relay method which is a premise of the present invention. 2...Repeater, 6...Slanted outer peripheral surface portion, P1-P
8... Area, 7a, 7b, 7C... Light emitting diode (LED) as a light emitting element, 8... Photodiode (PD) as a light receiving element

Claims (1)

[Claims] An optical signal based on spatially propagating light transmitted from a device is received by a light receiving element of a repeater, amplified within the repeater, and then converted into an optical signal based on spatially propagating light by a light emitting element of the repeater. In the relay method of space propagation optical communication for transmission to a device, the repeater is configured to include an inclined outer circumferential surface portion around a vertical axis that is inclined with respect to the central axis, and the inclined outer circumferential surface portion is configured to include: It is divided into a plurality of areas in the circumferential direction, and a light receiving element and a light emitting element are arranged in each area.When relaying signals, the light receiving element is scanned in each area so that it is ready for reception, and the light emitting element is A relay method in space propagation optical communication, characterized in that the element is scanned so as to become in a transmittable state in an area located on the opposite side of the central axis with respect to the area of the light receiving element in a receivable state.