JPS58188944A - Optical communication system - Google Patents

Abstract

PURPOSE:To perform effective optical communication between a single master station and plural slave stations, by providing the master station with directional characteristics of transmission and reception covering all the slave station and each slave station with those covering only the single master station. CONSTITUTION:The master station 12 which has LEDs and photodiodes on a spherical surface is provided on the attachment surface 11 of a ceiling or wall. The LEDs and photodiodes are arranged with nearly equal density on the spherical surface to obtain wide directivity. When transmission and reception are not performed simultaneously, one kind of diodes are used as LEDs during the transmission and as photodiodes during reception. On the other hand, the slave stations 13, 14, and 15 uses directional beam for transmission or reception and they emit light within an angle 2theta and receives light within the angle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an optical communication system comprising a single master station and a plurality of slave stations. The configuration of a wireless optical transmission/reception system that is suitable for inter-device communication between information processing devices and that allows slave stations to move freely is shown below.

[Description of prior art]

Between the computer terminal and the interface device for connecting it to the VR computer, it is necessary to perform communication between a large number of slave stations and the Chinese master station.In this case, the slave stations It is desirable that the installation location of the floor layout can be moved freely.
Further, it is desirable that the master station does not make any adjustments even if the position of the slave station changes.

Conventionally, the terminal and the interface device are connected by a copper wire or an optical cable, or by, for example, the method used in the US N-Connection Proceedings of Engineering I! KE vol, 6
7 NO, 11, NOVBMBERj979 pp14
74-1486 II Wirel, e8s In-Ho
use DateC○mmunication Vi
a Diffuse Infrar@d Rad
As stated in iat-1On#, the transmitting light is emitted almost omnidirectionally1, and the optical reception characteristics are also almost omnidirectional, giving the slave station a degree of freedom in movement.

However, the former method requires a lot of work to change the cable installation, and the latter requires a high output as a transmitter to compensate for the decrease in the received light level due to the diffusion of the signal light and the decrease in reception $2 due to the influence of background light. In addition to the disadvantage of requiring high speed, there are also problems in terms of safety for human eyes, power consumption, 'I#', heat, etc.

[Object of the Invention] The present invention improves the above, and aims to provide a wireless optical communication system that can reduce the transmitted optical power and increase the distance between the master station and the slave station. purpose.

[Key points of the invention]

In the master station of the present invention, both the transmitting and receiving systems are almost omnidirectional, so that there is no restriction on the position of the slave station, and in the slave station, both the transmitting and receiving systems are directional, and the transmitted light is It is characterized by effectively projecting optical power to the optical receiving system of the master station, and for reception, suppressing light from directions outside the master station to reduce the influence of background light.

[Explanation of Examples]

Embodiments of the invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of a communication system according to an embodiment of the present invention, in which communication between a single master station 1 and a plurality of slave stations 2 to 6 is 4i using Wi7. In order to freely select the position of the slave station, the light emitted by the master station must be omnidirectional or have a wide directivity that covers the entire movement range of the slave station.

For this reason, a light emitting diode is used as a light source. Light-emitting diodes that are molded into lens-like resin are particularly suitable. In this case #1, omnidirectional light is emitted mostly within the hemisphere, so if you mount the master station on the ceiling or wall, you can achieve the required omnidirectional or wide directional light without using any optical system. becomes.

Furthermore, if it is necessary to project almost uniform light over the entire space, or if the transmitted light output is insufficient for one light emitting diode, multiple tubes may be used.

On the other hand, the optical reception characteristics of the master station are numerous! In order to receive and accept light beams from slave stations whose light beams may change, it is necessary to have the same directivity as the transmitting beam.

Since each child station only needs to perform transmission and reception 5 to a single master station, it is possible to give directivity to both transmission and reception. FIG. 2 is a configuration diagram of a butterfly according to the present invention--an embodiment of the present invention, and is an example of the configuration when transmitting and receiving light within a hemisphere. 1lti, a surface for mounting on ceilings, strips, etc., and a main station with 12 light emitting diodes and photodiodes on a photosphere-shaped surface.

By arranging the light emitting diodes and photodiodes at approximately equal density on this hemispherical surface, a wide directivity can be obtained. In addition, if transmitting and receiving are not carried out at the same time, one type of diode tube can be used as a light emitting diode when transmitting, and when receiving K
It can also be used as an Fi photodiode.

The slave stations 13 to 15Fi are configured to have directional beams for transmission and reception, and each transmits light within an angle of 20,
It also receives light within this angle. For example, even if the optical axis 19 of the slave station 15 is slightly deviated from the master station 12, the configuration is such that communication is possible if there is a new station within an angle of 2θ.

Next, the advantage of providing directivity only to the slave stations will be explained.

FIG. 3 is a diagram showing an example of a configuration of an optical transmitting/receiving system of a slave station.

In this example, the Fi light emitting diode is used as a light source by supplying a forward current during transmission, and is used as a photodiode by applying a reverse bias voltage during reception, and the lens 21 is shared for transmission and reception. Now, if the effective diameter of the light emitting diode is A and 17, and the focal length of the lens 21 is f, then the light spreading angle is θ, and the light emitting diode is the lens 21.
When the expansion AK# of the lens is extended, the bending of the light on both the left and right sides of the lens is equal.
The incident component [7] is focused within the angle of the angle and is emitted. Therefore, when the optical axis 26 is aligned in the direction of the master station, the amount of signal light received by the optical receiving system of the master station is far greater than when there is no lens 21 and the output light from the light emitting diode is diffused in all directions. many. This makes it possible to reduce the area of the receiving system of the master station by that much, and the amount of unnecessary background light received is reduced. It is possible to reduce the output light power of a light emitting diode.

On the other hand, when receiving data from a slave station, only light within the range of the angle θ described above enters the light emitting diode 20, so background light is reduced and the ratio of the surface area of the lens 21 to the effective area of the light emitting diode is reduced. Can receive many signal lights. The transmission optical power of the master station can be reduced from this kw.

In the above explanation, the transmitting and receiving diodes are shared, but it is also possible to use a seven-way diode dedicated to receiving.

In this case, it is necessary to use both KFi, a lens-light-emitting diode combination, and a lens-photodiode combination at the same time, or to combine the light-emitting diode and photodiode into a single lens by means of a half mirror.

Although the above description deals with bidirectional communication, the present invention can also be implemented in the case of unidirectional communication from a master station to a slave station or from a slave station to a master station. In this case as well, if the master station only transmits, the background light elimination effect of the slave station can lower the transmitting optical power of the master station, and if the slave station only transmits, the optical power reaching the master station will decrease. Since this increases, the transmission optical power of the slave station can be lowered.

[Explanation of effects]

As described above, according to the present invention, in communication between a large number of slave stations and a single master station, both the master station and the slave stations have almost no direction, even if the slave stations are configured to change freely. This has the advantage that the optical transmission power can be significantly lowered compared to the case where the transmitting/receiving characteristics are similar, and the distance between the #i master station and the slave station can be increased.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2 is a block diagram of another embodiment of the present invention. FIG. 5 is a partial configuration diagram of the embodiment of the slave station in FIG. 2. l...Master station, 2-6...Slave station, 12...Master station, 1
3 to 15...Slave station, add...Light source or receiver, 2
1... Lens, θ... Angle that determines the transmitting and receiving directivity. Patent Applicant NEC Corporation Representative Patent Attorney Naotaka Ide? P11 Day 2 Figure '25 M3 Figure

Claims (1)

[Claims] (1) In a system that performs optical communication between a single master station and a diagonal number of slave stations, the transmission and/or reception directional characteristics of the master station are busy so as to envelop all the slave stations with which it communicates. An optical communication system characterized in that the transmission and/or reception directional characteristics of the slave stations are configured narrowly so as to envelop the single master station.