JPH0797762B2 - Relay method in space propagating optical communication - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay method for performing communication by spatial light propagation using light as a carrier, and more particularly to a relay method optimal for indoor space propagation optical communication. is there.

2. Description of the Related Art In recent years, a spatial propagation optical communication system has been developed in which information data is spatially transmitted and received using light as a carrier wave, and in particular, it is the same as various terminal devices such as facsimiles, printers, cash registers, etc. as slave stations installed indoors. 2. Description of the Related Art A system for performing communication with a device as a master station placed in a room, such as a host computer, by spatial light propagation is being implemented.

Conventionally, in such an indoor space propagation optical communication system, as shown in FIG.
A repeater 2 is attached to each of the indoor terminals 3a to 3c and the repeater 2 performs transmission and reception by spatially propagating light, while the repeater 2 and the master station 4 such as a host computer are connected to each other. ,
Wire 5 such as optical fiber or ordinary electric wire cable
It was usual to connect and disconnect via the wire 5 and perform transmission / reception by non-spatial transmission. However, when actually applying such a system,
There is an inconvenience that the wiring work for connecting the repeater 2 and the master station 4 with the wire 5 is required, and that when the master station 4 is moved, the wiring must be changed again.

Therefore, recently, as shown in FIG. 8, not only between the terminals 3a to 3c and the repeater 2, but also between the repeater 2 and the master station 4 such as a host computer, an optical signal generated by the spatial propagation light is used. Transmission and reception systems are being developed. According to such a system, no wiring work is required, and the master station can be arbitrarily moved according to indoor conditions and rearrangement.

By the way, the repeater used in the system as shown in FIG. 8 is basically designed to be able to receive an optical signal from any location in the room and to transmit an optical signal to any location in the room. In addition, it is desirable that both the receiving side (light receiving side) and the transmitting side (light emitting side) be omnidirectional. However, a light emitting element used for this kind of communication, such as a light emitting diode, has a strong directivity and is normally effective only in an angle range of about 15 to 20 °, so that transmission (light emission) is performed nondirectionally. In order to achieve this, it is necessary to cover the whole area of the room with a large number of light emitting elements of at least 40 to 50.
When a large number of light emitting elements are used in this way, there arises a problem that the current consumption of the repeater as a whole becomes extremely large even if the current consumption per light emitting element is small.

In the system shown in FIG. 8, when the receiving side (light receiving side) and the transmitting side (light emitting side) are both omnidirectional,
In addition to the spatially propagating light from the original terminal equipment entering the light receiving element of the repeater, the spatially propagating light emitted from the light emitting element of the repeater itself may enter due to multiple reflections and irregular reflections in the room. In such a case, the received signal due to the original propagating light may be disturbed by the signal due to reflection, and accurate signal relay may not be performed. Such jamming is similar to multipath jamming in wireless communication and is therefore also referred to hereinbelow as multipath jamming.

Regarding the former one of the above-mentioned two kinds of problems, that is, the problem of current consumption due to the use of a large number of light emitting elements, one solution has already been proposed in JP-A-59-133744. In this proposed repeater, multiple units that receive and emit light only within a certain range are prepared, and those units can be attached to and removed from the repeater mounting holder in all directions. As a result, the number of light emitting elements and light receiving elements actually used is reduced by mounting the unit only in that direction according to the arrangement direction of the terminal device or the master station, and the current consumption is reduced.

Problems to be Solved by the Invention In the above-mentioned proposed repeater, although the problem of current consumption can be solved to some extent, multipath interference is still unsolved. That is, even with 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 reflection and irregular reflection.

In addition, although the proposed repeater has the effect of reducing the current consumption, the current consumption may increase in some cases. That is, when the number of terminals is large and the terminals are arranged apart from each other, the number of units to be attached to the repeater also increases, and in that case, the current consumption must increase to some extent. I didn't get it.

In addition, the above-mentioned proposed repeater has a problem that the unit must be attached and detached according to the arrangement of the terminal and the master station, which is troublesome for that purpose.

The present invention has been made in view of the above circumstances, and in a relay method in space propagating optical communication, particularly in a relay method of a method in which transmission and reception between a repeater and another device are all performed by optical signals by space propagating light, Basically, it is omnidirectional, and the current consumption can be made extremely small. At the same time, the reliability of data transmission can be increased by preventing interference such as multipath interference, and other troublesome work etc. The purpose of the present invention is to provide a relay method that eliminates the need.

MEANS FOR SOLVING THE PROBLEMS The present invention is directed to receiving a light signal of spatially propagating light transmitted from a device by a light receiving element of a repeater, amplifying the signal in the repeater, and spatially propagating the light signal of the repeater by a light emitting element. In the relay method of space propagation optical communication for transmitting to another device as an optical signal by light, the repeater is configured to include an inclined outer peripheral surface portion that is inclined with respect to the central axis line around a vertical axis line, The inclined outer peripheral surface portion 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, so that the light-receiving element can be received in each region during signal relay. And the light-emitting element is scanned so that the light-emitting element is in a transmittable state in an area that is always located on the opposite side of the area of the light-receiving element that is in a receivable area with the central axis interposed therebetween. To do.

Function In the relay method of the present invention, the relay is installed, for example, on the ceiling in the room. The spatially propagating light, which is an optical signal transmitted from a device such as a terminal, is incident on a region (or a region adjacent to the device) facing the direction of the device in each region of the inclined outer peripheral surface of the repeater. Since the light-receiving element is scanned so that it can be received in each area, when the light-receiving element in the area where the optical signal from the device is incident becomes receivable, the optical signal is electrically converted by the light-receiving element in that area. It is converted into a signal and taken into the repeater. The signal captured in this way is demodulated in the repeater according to the signal modulation method, modulated or interpolated, or amplified or waveform-shaped, and then propagated spatially from the light emitting element of the repeater. It is transmitted as an optical signal by light. Since the light emitting element is also scanned so that it can be transmitted in each area, the optical signal as a transmission signal is also sequentially transmitted from the light emitting element in each area. Even if the receiving device such as a host computer is located in any direction 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 are The transmitted optical signal is always received by the light receiving unit of the receiving side device.

Here, the scanning phase of the light receiving element and the light emitting element is 180 degrees so that the area of the light receiving element in the receivable state and the area of the light emitting element in the transmissible state are always located on the opposite sides of the central axis. Deviated. This means that the area to which the light emitting element to which the optical signal is currently transmitted from the repeater and the light receiving element in the area in the vicinity thereof are not in the receivable state, and the area to which the light emitting element to which the optical signal is being transmitted belongs. Since it means that only the light receiving element in the area on the opposite side is ready to receive, the optical signal emitted from that light emitting element is incident on the light receiving element in the ready state due to multiple reflection and irregular reflection in the room. Therefore, the risk of signal transmission accuracy deterioration due to multipath interference is significantly reduced.

Further, as is apparent from the above, not only the light-receiving element but also the light-emitting element are not set to the transmittable state at the same time, and scanning is performed so that the transmittable state is sequentially set for each area. Only a small part of all the light emitting elements are operating, and therefore, the current consumption is much smaller than that in the case where all the light emitting elements are driven at the same time.

Example An example of the relay method of the present invention will be described below with reference to FIGS.

FIG. 1 and FIG. 2 show an example of the appearance of the repeater 2. In this example, the inclined outer peripheral surface portion 6 inclined by a predetermined angle θ with respect to the vertical central axis 0 of the repeater 2 has a circumference. It is divided into _eight regions P _{1 to} P ₈ at equal intervals in the direction. In each of the regions P _{1 to} P ₈ , three light emitting diodes (hereinafter referred to as “LED”) 7a, 7b and 7c as light emitting elements and one photodiode (hereinafter referred to as “PD”) as a light receiving element are provided.
8 are provided. Here, the three LEs in each area P _{1 to} P ₈
D7a to 7c are attached so that the angles are slightly different from each other.

PDs, LEs belonging to the respective regions P _{1 to} P ₈ when relaying an optical signal by spatially propagating light using such a repeater 2
An example of the operating state of D is shown in FIG. In FIG.
A white area surrounded by a solid line indicates an area in which the LED is in a transmittable state, and hereinafter, an area in which the LED is in a transmittable state, that is, a light-emissive state is referred to as a light emitting surface. In FIG. 3, the shaded area indicates the area in which the PD is in the receivable state. In the following, the area in which the PD is in the receivable state, that is, in the state in which the optical signal can be received and the signal can be taken in is shown. It is called the light-receiving surface.

As shown in FIG. 3, for example, when the region P ₁ is the light receiving surface, the region P ₅ on the opposite side of the region P _{1 with the} central axis 0 interposed therebetween is the light emitting face. The light-receiving surface moves, for example, in the clockwise direction as shown by the solid line arrow in Fig. 3, and changes from the state of Fig. 3 to P ₁ → P ₂ → P ₃ → P ₄ → P ₅ → P ₆ → P ₇ → P ₈ . Each region becomes a light receiving surface in order. 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 in FIG. 3, P ₅ → P ₆ → P ₇ → P ₈ →
Each area becomes a light emitting surface in the order of P ₁ → P ₂ → P ₃ → P ₄ . Therefore, the area on the opposite side of the central axis 0 is always the light receiving surface,
It will be the light emitting surface.

Note that in the example of FIG. 3, the area that is the light emitting surface at the same time at one time is one area, and the area that is the light emitting surface is one area. However, depending on the case, there are two areas or three areas. May be the light receiving surface or the light receiving surface at the same time. FIG. 4 shows an example in which two areas simultaneously serve as a light receiving surface and two areas serve as a light emitting surface. In this case, for example, P ₁ ,
P ₂ region (P ₁ + P ₂₎ has a region (P ₅ + P ₆₎ is the light emitting surface of P _5, P ₆ of the opposite side in a state in which a light receiving surface, the light receiving surface from the state (P ₁ + P ₂ ) → (P ₂ + P ₃ ) →
_{(P 3 + P 4) →} (P 4 + P 5) → (P 5 + P 6) → (P 6 + P 7) →
Move to (P ₇ + P ₈ ) → (P ₈ + P ₁ ) → (P ₁ + P ₂ ), and also move the light emitting surface. Of course, it is not always necessary to match the number of regions serving as light-receiving surfaces at the same time as the number of regions serving as light-emitting surfaces.

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

In FIG. 5, eight receiving circuit units 9 _{1 to} 9 ₈ correspond to the PDs in the areas P _{1 to} P ₈ , respectively, and from these receiving circuit units 9 _{1 to} 9 ₈ , respectively. The optical signal from the device to the PD corresponding to the unit, for example, when an optical signal obtained by CMI-modulating the information data to be transmitted is incident, a data signal obtained by converting the optical signal into an electrical signal,
A reception detection signal indicating that an optical signal is incident is output. The reception detection signal is sent to the reception unit determination circuit 10 and it is determined which of the reception circuit units 9 _{1 to} 9 ₈ has received it, in other words, which of the regions P _{1 to} P ₈ the optical signal has entered. The result is given to the system controller 11. One of the receiver circuit units 9 ₁
Data signal output from -9 _8, the switch circuit 12 ₁ to 1
It is sent to the demodulator 13 via the 2 _8. Switch circuit 12 _{1 to} 12
₈ is directly on / off controlled by a switch control circuit 14, and the switch control circuit 14 is instructed by the information from the system controller 11 which switch circuit 12 _{1 to} 12 _{8 is} to be turned on or off. . The demodulator 13 not only demodulates a CMI-modulated data signal, but also performs signal interpolation and error correction, and its operation is controlled by a signal from the system controller 11. The demodulation output signal of the demodulator 13 is input to the modulator 15 and is CMI-modulated again.
The modulated signal is given to the transmission circuit units 16 _{1 to} 16 ₈ . These transmission circuit units 16 _{1 to} 16 ₈ respectively cause the LEDs 7a to 7c of the respective regions P _{1 to} P ₈ to emit light in accordance with the data signal from the modulator 15, and transmit the optical signal as spatial propagation light. And these transmitter circuit units 16 ₁
To 16 _8, in the order specified by the control signal from the transmission unit control circuit 17, it is scanned controlled so as to sequentially transmittable state (light emission state).

In the circuit configuration shown in FIG.
12 _{1 to} 12 ₈ are only data signals from the receiving circuit units 9 _{1 to} 9 ₈ in the area located on the opposite side to the area corresponding to the transmitting circuit units 16 _{1 to} 16 ₈ in the transmittable state (light emitting state) Is controlled by the switch control circuit 14. For example at the time when the transmission circuit unit 16 _fifth region P ₅ is in the transmittable state, the region of the opposite side with respect to the region P ₅
Switch circuit for output circuit of receiver circuit unit 9 ₁ for P ₁ 12 ₁
Only the data due to the optical signal incident on the PD in the area P ₁ is turned on and the other switch circuits 12 _{2 to} 12 ₈ are turned off, so that the areas P _{2 to} P ₈ are turned on.
The data output signals of the receiving circuit units 9 _{2 to} 9 ₈ due to the optical signal incident on the PD of cannot be taken in. Then, as the transmission enable states of the transmission circuit units 16 _{1 to} 16 ₈ are sequentially scanned, the ON states of the switch circuits 12 _{1 to} 12 ₈ are scanned, and thereby the transmission circuit units 16 in the area in the transmission enable state are scanned.
_{1-16 8} always receive circuit unit 9 ₁ ~ opposite to the area to
Only the data signals from 9 ₈ will be accepted.
The state in which the switch circuit of the output path of the receiving circuit unit in a certain area is turned on in this way corresponds to the receivable state for the PD in that area.

As described above, according to the circuit configuration of FIG. 5, the optical signal can be received and transmitted, that is, the optical signal can be relayed by the scanning method as shown in FIG.

In the above description with reference to FIG. 5, when the number of areas that are simultaneously in the receivable state and the number of areas that are simultaneously in the transmissible state are 1, that is, the number of areas that are both the light-receiving surface and the light-emitting surface are both. Although the case where the number is 1 has been described, the number of regions serving as the light-receiving surface and the light-emitting surface can be arbitrarily changed at the same time by setting the system controller 11 with the same circuit configuration of FIG.

Also, the scanning speed can be arbitrarily changed by setting with the system controller 11, but generally one signal (1 bit signal) is ensured from the area at an arbitrary position to the time when the entire area is scanned. To send and receive
It is desirable to scan at a frequency equal to or higher than the frequency obtained by multiplying the frequency of the original signal bit by several times the number of divided areas, for example, 2-3 times. That is, in the case of being divided into eight areas as described above, one signal is transmitted or received by scanning all eight areas, and therefore at least one bit of the original signal is at least It is necessary to scan 8 areas, and moreover, a scanning frequency that is several times higher than that is necessary in order to increase the reliability and reliability of data transmission / reception. × A scanning frequency of about 2 to 3 times or more is required.

In the example of FIGS. 1 to 4, the inclined outer peripheral surface portion 6 of the repeater 2 is used.
Has been divided into _eight areas P _{1 to} P ₈ , but the number of area divisions is not limited to eight, for example, the sixth area.
As shown in the figure, it may be divided into ₁₆ regions P _{1 to} P ₁₆ .
Also in this case, the number of regions that simultaneously serve as the light-receiving surface and the number of regions that simultaneously serve as the light-emitting surface are not limited to one, but can be about 2 to 4.

In addition, in the above-mentioned examples, it is assumed that the scanning is performed so that the areas that are sequentially adjacent to each other are in the receivable state and that the areas that are sequentially adjacent to each other are in the transmissive state, but in some cases, some areas are scanned. You may scan while skipping. For example, as shown in FIG. 2, when the number of area divisions is eight, scanning may be performed while skipping two areas. In this case, if the area P ₁ in FIG. 2 is scanned in the clockwise direction, the area in the receivable state is P ₁ → P ₄ → P ₇ →
Scanning will be performed in the order of P ₂ → P ₅ → P ₈ → P ₃ → P ₆ → P ₁ .
Of course, the area in the transmittable state is scanned so as to be the area on the opposite side of the area in the receivable state.For example, in the above example, P ₅ → P ₈ → P ₃ → P ₆ → P ₁ → P It will be scanned in the order of ₄ → P ₇ → P ₂ → P ₅ .

Also, in the example of FIGS. 1 and 2, three LEDs 7a are provided in one area.
7c are provided, the number of LEDs arranged in one area can be arbitrarily determined as needed. Furthermore, the first
In the example of FIG. 2 and FIG. 2, each region P _{1 in} which the inclined outer peripheral surface portion 6 is divided
Although have to P ₈ to the respective inclined planes, in some cases it may be a curved surface may be a part of a spherical surface continuous in its entirety when the inclination outer peripheral surface 6. When the inclined outer peripheral surface portion 6 is formed as a part of a continuous spherical surface as described above, each of the areas P _{1 to} P ₈ divided in the circumferential direction is also a part of the same spherical surface. Will not appear.

EFFECTS OF THE INVENTION As is clear from the above description, according to the relay method of the present invention, the optical signal by the spatially propagating light transmitted from the device is received by the light receiving element of the relay, and is amplified in the relay. When transmitting to another device as an optical signal by spatially propagating light by the light emitting element of the repeater, regardless of the position of the transmitting side device and the receiving side device, reception and transmission are basically omnidirectional. Although it can be performed, the number of light emitting elements that are in the transmitting state (light emitting state) at the same time is significantly smaller than the number of all the light emitting elements, so that the power consumption is extremely low and the light emitting element of the repeater is required. The optical signal transmitted from the receiver is less likely to be received by the light receiving element of the same repeater due to multiple reflections or irregular reflections in the room.Therefore, the signal due to the reflection interferes with the original received signal. Extremely low risk of injury. Therefore, according to the relay method of the present invention, it is possible to perform omnidirectional relay of the all-space optical propagation method that does not use wires at low running cost and high signal transmission accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing an example of the appearance of a repeater used in a relay method of the present invention, FIG. 2 is a bottom view of the repeater of FIG. 1, and FIG. 1 and 2 are schematic views showing an example of the scanning condition of the repeater, and FIG. 4 is a schematic diagram showing another example of the scanning condition of the repeater shown in FIGS. 1 and 2. FIG. 5 is a block diagram showing an electric circuit configuration of a repeater used in the relay method of the present invention, and FIG. 6 is a bottom view showing another example of the repeater used in the relay method of the present invention. FIG. 8 is an explanatory diagram showing an example of a conventional relay method, and FIG. 8 is an explanatory diagram showing a conventional relay method which is the premise of the present invention. 2 ...... repeater, 6 ...... inclined outer peripheral surface, P ₁ to P ₈ ...... region,
7a, 7b, 7c ... Light emitting diodes (LE
D), 8 ... Photodiode (PD) as a light receiving element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04B 10/17 10/22

Claims (1)

[Claims] 1. A light receiving element of a repeater receives an optical signal of spatially propagating light transmitted from a device, amplifies this in a repeater, and a light emitting element of the repeater converts the optical signal into another optical signal of spatially propagating light. In a relay method of space propagating optical communication for transmitting to a device, the repeater is configured to include an inclined outer peripheral surface portion that is inclined with respect to a central axis thereof around a vertical axis, and the inclined outer peripheral surface portion is a peripheral portion. The light receiving element and the light emitting element are arranged in each of the areas, and when the signal is relayed, the light receiving element is scanned so as to be in a receivable state for each area, and the light emitting element is also provided. In a space propagating optical communication system, in which an area of the light receiving element in a receivable state is scanned so as to be in a transmissible state in an area located on the opposite side of the central axis. Method.