JPH03109837A - Optical data transmission system - Google Patents

Abstract

PURPOSE:To attain optical data multiplex transmission with the same carrier frequency and not requiring tight optical axis alignment between an exchange and a terminal equipment by providing a reception means in which photodetectors are planerly arranged, a transmission means in which light emitting elements with directivity are planerly arranged, an optical means guiding a transmission light and a reception light and a processing means. CONSTITUTION:An exchange 20 is provided with a reception section 32 in which photodetectors are planerly arranged, a transmission section 34 in which light emitting elements with directivity are planerly arranged similarly, optical means 36, 38 guiding a transmission light and a reception light, and a processing means 40 processing the transmission/reception signal between the reception means 32 and the transmission means 34 and the position information of terminal equipments 24, 26 and the exchange applies transmission/reception of optical data with plural terminal equipments 24, 26 having one set of light emitting and light receiving elements. The exchange 20 detects the position of the transmission terminal equipment based on the position of the photodetector receiving a light and forms a line with a light emitting element at a position effective to the transmission. Thus, a 2-way multiple space propagation light utilized optical data transmission system is realized, in which no optical alignment between the transmitter and the receiver is required and the terminal equipments 24, 26 are moved freely and their positions are detectable.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an optical data transmission system applied to a multiple-line simultaneous communication system using spatially propagating light, particularly an optical data transmission system applied to a local area network or other internal optical data communication. Regarding data transmission systems.

[Prior Art] As multiplexing methods for space propagation optical communication systems, there are 1) methods using different wavelengths, 2) methods using space division or applying polarization, and 2) methods using time division.

As an example of different wavelengths,
61 r Space Propagation Optical Transmitter/Receiver". As shown in FIG. 9, this device has a space C between terminals A and B, each of which has a plurality of transmitting sections 1 and a plurality of receiving sections 2, which are mutually coupled with an optical fiber 3 and an optical coupler 4. is transmitted and received as a single beam of light with multiple wavelengths through a lens 5 whose direction is adjusted by a direction adjustment mechanism 6. here,
Since the space C is assumed to be outdoors, the following effects can be obtained: only the lens system is exposed to the outdoor environment, directivity adjustment is easy because of the single beam, and outdoor structures can be reduced.

In addition, as an example of the conventional technology of the space division multiplexing method,
-109867 r TV remote control position detection device". This device automatically adjusts the absolute volume and balance of the left and right speakers of the TV according to the position of the person watching the TV. It is composed of a light receiving section 11. The remote controller 7 has means for generating position detection signals, communication signals, and infrared signals (not shown), and the light receiving section 11 has a nondirectional communication signal detection light receiving element 8 and a reflector IO to generate high directivity. It has a plurality of light receiving elements 9 for remote control position detection provided therein. The direction θ of the position of the person watching the television is determined by the directivity corresponding to the number of light receiving elements 9 for detecting remote control positions, and the distance is determined from the intensity of the received light of the light receiving elements 8 for detecting communication signals.

In the case of the above-mentioned multiplexing method using different wavelengths, it is necessary to combine different wavelengths for the same number of lines, and therefore, it is necessary to combine the number of optical transmitters and optical transmitters according to the number of combinations of wavelengths. . Further, in the embodiment shown in FIG. 9, the movable range of the terminals of the optical transmitting section and the optical receiving section is limited to the connection range of the optical fiber 3 in each terminal.

On the other hand, when applying the latter method of space division multiplexing or polarization, in order to prevent interference between lines, the direction characteristics of the transmitted light or the received light must be narrow directional characteristics, and the direction must be precisely adjusted for each terminal. There is a need.

Furthermore, the time division multiplexing method has the disadvantage that it is necessary to synchronize each terminal in principle and that continuous data transmission and reception cannot be performed.

[Problem to be Solved by the Invention 1] The present invention solves the drawbacks of the prior art, and provides a bidirectional system that eliminates the need for optical axis adjustment between the transmitter and receiver, allows the terminal to move freely, and allows its position to be detected. The purpose of this invention is to provide a spatially multiplexed optical data transmission system using spatially propagated light.

[Means for Solving the Problems] An optical data transmission system according to the present invention includes a receiving section in which light receiving elements are arranged in a planar manner, a transmitting section in which directional light emitting elements are arranged in a planar manner, and guiding transmitted light and received light. transmitting and receiving optical data to and from a plurality of terminals each having a set of light transmitting and receiving elements, by means of an exchange having optical means for processing, receiving means, and processing means for processing transmission and reception signals between the transmitting means and position information of the terminals; The exchange is characterized in that it detects the position of a transmitting terminal based on the position of a light-receiving element that receives light, and also forms a line with a light-emitting element at a position effective for transmission.

[Function] The present invention uses a space division multiplexing method, but in order to avoid narrow directivity transmission and reception characteristics, which are the drawbacks of the same method, and the requirement for strict directional adjustment of the transmitter and receiver, the switching system interposed between the terminals is It is an array with a large number of light-emitting and light-receiving elements laid out in a planar shape. This array can be easily fabricated using current semiconductor and electronic technology. An optical system consisting of a lens common to all light receiving elements is arranged in the front direction perpendicular to the array surface of the light receiving element, so that light from the transmitting terminal arriving from a direction forming an arbitrary angle with the array surface is always directed to one of the light receiving elements. By adjusting the focus to be focused on the light receiving element, the position of the transmitting terminal can be centrally determined from the position of the light receiving element.

An optical system consisting of a lens common to all the light emitting elements is arranged vertically in the front direction on the array surface of the light emitting elements, and based on the position information, the light emitting elements effective for transmission are selected and the sending angle is set. For example, a return circuit from the receiving terminal to the transmitting terminal can be formed. In this case, the light transmitted from the transmitting terminal only needs to illuminate the light-receiving optical system of the exchange with an amount of light above a certain level, and □ Directivity is not a particular issue. By providing this information, interference with the Brazilian line and interception by third parties can be prevented.

Similarly, a line is formed between another transmitting terminal and the exchange, and one terminal and multiple terminals are connected through the exchange? !
A large number of communication lines between one terminal and a plurality of other terminals are simultaneously formed.

[Embodiments] Next, embodiments of the optical data transmission system according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the basic configuration of a system according to the present invention. The terminals 24, 26, . . . , 28 and the exchange 20 are bidirectionally connected by light via a light transmitting/receiving section 22.

By installing the exchange 20 in a place with good visibility, such as above the ceiling or wall, wireless communication without crosstalk between terminals is facilitated.

FIG. 2 is an embodiment of the exchange shown in FIG.

The exchange 20 includes a light transmitting/receiving section 22 and an information processing section 40. The light transmitting/receiving section 22 includes a two-dimensionally laid out light receiving element array 32. Similarly, it is composed of a light emitting element array 34, a half mirror 36, and a lens 38. The information processing section 40 is composed of a control circuit 42 and a switching circuit 44.

Next, the operation of this device will be explained, taking as an example the case where transmission is performed from the terminal 24 to the terminal 26. The transmitted light from the terminal 24 is transmitted through the half mirror 36 by the lens 38 and focused on the element AR of the light receiving element array 32. Element A
R is selected centrally depending on the location of the terminal 24. The information on the transmitted light includes an identifier signal between the own terminal and the other terminal, and transmission parameters for line selection. to the latest location information of the terminal 24.

Next, the control circuit 42 similarly detects from the identifier signal that the other terminal is the terminal 26, and selects the corresponding element BS of the light emitting element array 34 from the already stored position information of the terminal 26. A calling signal from the terminal 24 is transmitted to the terminal 26 via the half mirror 36. Terminal 2
When the terminal 6 receives the signal from the exchange 20, it sends its own terminal's identifier signal to the exchange 20 as a response signal. When the transmitted light from the terminal 26 reaches the exchange 20, it is transmitted through the half mirror 36 by the lens 38 and focused on the element BR of the light receiving element array 32 corresponding to the position of the terminal 26. Furthermore, when the control circuit 42 confirms the connection with the terminal 26, it selects the element AS of the light emitting element array 34 corresponding to the position of the terminal 24, and notifies the terminal 24 of the connection with the terminal 26.

The exchange circuit 44 controls the connection between the elements AR1BR of the light receiving element array 32 and the elements AS and BS of the light emitting element array 34, and forms a bidirectional communication line. When a predetermined communication line is formed, the control circuit 42 enters a standby state in which it receives signals from other terminals in order to independently form lines between the other terminals. Further, the control circuit 42 periodically causes the light emitting elements of the light emitting element array 34 to emit light one after another, receives response signals from other terminals at the light receiving element array 32, and stores the latest position of each terminal.

The line is disconnected when one of the terminals stops transmitting light, which is detected by the information processing unit 40 and restores the connection state.

The received light is focused on the light receiving element array 32 at a focal point large enough to be received by one of the elements, and when multiple elements receive light, the SN determines which signal to select or combine. The control circuit 42 determines the state of the propagation path, such as ratio and fading.

FIG. 3 shows an example of the main circuit configuration of the information processing section 40 of the exchange shown in FIG. 2. The same functional parts are designated by the same reference numerals as those shown in FIG. 2, and only the main parts are given the same reference numerals. Photodiode AR46 as a light receiving element and LED BS as a light emitting element
This is an example in which one each of 60 is taken out and connected with a crossbar type exchange circuit and a control circuit using a microcomputer. The signal received by the photodiode AR46 is amplified by the amplifier 48 and first inputted to the signal detection circuit section 100. The signal detection circuit section 100 has a function of detecting which light receiving element receives light and sending a human signal to the data register 50.

When the two D flip-flops 52 and 54 are both cleared and in a ready state, only the signal received by one light receiving element is connected to the data register 50. At this time, the D flip-flops 52 and 54 take the value of state 3 in FIG. In this example, terminal K is connected and a signal is input to data register 50 from the line R.

When a signal is input to the data register 50, the microcomputer 5
An interrupt signal is sent to 6. The microcomputer 56 determines the terminal identifier, position, destination, and transmission parameters from the data register 50 value and the D flip-flop 52.54 value. Next, the microcomputer 56 causes the light emitting element 60 corresponding to the destination terminal to emit light, calls the terminal J (not shown), and when a response is confirmed, directly connects the receiving circuit SK to the transmitting circuit TJ on the analog switch 58. Reconnect. Then, the value of the D flip-flop 52 is changed from 1 to Ol
That is, after entering state 2 or 63 in FIG. 4 and prohibiting human input from other terminals, the signal detection circuit section 100 is returned to the standby state.

FIG. 5 shows another embodiment of the light transmitting/receiving section used in the present invention. In the embodiment shown in FIG. 2, the light receiving element array and the light emitting element array 66 are formed on different planes, but in the embodiment shown in FIG. The two-dimensional light emitting and receiving elements 64 are formed alternately on the top, and the half mirror is omitted. In this device, the distance between the adjacent elements of the light-emitting element and the light-receiving element becomes large, and a dead zone may occur. However, the area of the elements is sufficiently small compared to the size of the focal point, and the elements are arranged densely. Therefore, the above problem can be avoided by controlling the signals of a plurality of elements as described above.

FIG. 6 shows a further embodiment of the light transmitting/receiving section in the present invention. A filter 76 that passes only light from the terminal is placed on the light receiving element array 72, and a transparent light emitting element array 74 is mounted on top of the filter 76 to form an optical system consisting only of the lens 70. However, in this embodiment, the wavelength 1 passing through the filter 76 is
Since the wavelength 2 is used as the received light and the blocked wavelength 2 is used as the transmitted light, it is necessary to use light of two types of wavelengths.

FIG. 7 shows an example of a system in which there are connections between a plurality of exchanges and a plurality of external lines. Let us consider the case of transmitting from the external line 82 to the terminal 90. Signals from external line 82 are transmitted through terminal 86 to switch 78. Further, the transmission to the exchange 80 may be performed using either a method using light or a method in which the exchanges are directly connected to each other with a cable 94. As a method using light, non-line-of-sight transmission or long-distance transmission is performed from the exchange 78 via the repeater 88. Similarly, it can also be transmitted to the terminal 86 from an external line 84 connected to the exchange 80. The interface between an external line and a terminal or exchange can be easily achieved by the electrical/optical mutual conversion using the photodiode and LED described in the embodiment of FIG.

FIG. 8 further shows an embodiment of a system in which a portion of the optical signal is routed through optical fiber 96.

In this embodiment, an exchange 78, an exchange 80, and a terminal 90 are connected by an optical fiber 96 to cope with non-line-of-sight transmission, long-distance transmission, and secret transmission due to barriers such as walls.

[Effects of the Invention] According to the present invention, the positions of terminals are detected centrally, there is no need for strict optical axis alignment between the exchange and the terminals, and optical data multiplex transmission using the same carrier frequency is possible. Furthermore, terminals can be moved freely within a range of sufficient signal strength, and the transmission range can be easily expanded because there is great flexibility in connection with cables, optical fibers, and repeaters.

The system according to the present invention can be applied to internal optical data communications, such as internal optical data communications, internal location confirmation devices, internal mobile telephones, paging, large exit management, security, and local area networks.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of an optical data transmission system according to the present invention, FIG. 2 is a diagram showing an embodiment of a switch used in the system of FIG. 1, and FIG. 3 is a diagram showing an information processing section of the system according to the present invention. FIG. 4 is a truth table of the D flip-flop shown in FIG. 3. FIGS. , FIGS. 7 and 8 are diagrams showing other embodiments in which the transmission range is expanded using multiple exchanges and cables or optical fibers in the system according to the present invention, and FIG. 9 is a diagram showing a conventional space propagation optical transmission/reception system. Fig. 10 is an explanatory diagram of a conventional TV remote control position detection device.Explanation of symbols of main parts Exchanger Light transmitter/receiver section Light receiving element array Light emitting element array Half mirror Lens Information processing section Control circuit Switching circuit Data register D flip-flop 5, microcomputer analog switch, exchange, repeater cable, optical fiber, signal detection circuit section

Claims (1)

[Claims] 1. In an optical data transmission system in which one exchange and a plurality of terminals are connected by light propagating in space, each of the plurality of terminals has a set of light transmitting/receiving elements; The exchange includes a receiving means in which light receiving elements are arranged in a planar manner, a transmitting means in which directional light emitting elements are arranged in a planar manner, an optical means for guiding the transmitted light and the received light, the receiving means and An optical data transmission system comprising processing means for processing transmitted and received signals between transmitting means and position information of the terminal. 2. The optical data transmission system according to claim 1, wherein in the exchange, the light receiving elements and the light emitting elements are alternately arranged on the same plane. 3. In the system according to claim 1, the exchanger is characterized in that an optical filter is provided on the light receiving element, and a planarly transparent light emitting element is further provided on the optical filter. Optical data transmission system.