JP2001044943A - Optical bus system device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform communication between two optical buses without performing optical-to-electrical and electrical-to-optical conversions and also to simultaneously perform communication of respective intra-optical buses and respectively inter-optical buses without increasing the degree of multiplexing of multiple transmission. SOLUTION: Modules M11, M12,..., M1n are connected to an optical bus 1, and modules M21, M22,..., M2m are connected to an optical bus 2. The modules M11, M12,..., M1n and the modules M21, M22,..., M2m are respectively provided with a light emitting element and a light receiving element so that they can transmit and receive an optical signal. The buses 1 and 2 are connected by an optical transmission line 3 without performing optical-to-electrical and electrical-to-optical conversions. The line 3 is provided with a channel setting part 4 setting its transmission channel. The part 4 is composed of a wavelength filter, a polarization filter, etc., in accordance with a multiplex transmission system. The transmission channels of the buses 1 and 2 are defined as two channels for channels 1 and 2, and the channel 1 is set for communication between the buses 1 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical bus system, and more particularly, to an optical bus system in which a plurality of optical buses are connected to extend the optical bus.

[0002]

2. Description of the Related Art As the data processing speed of an LSI (semiconductor integrated circuit) has been dramatically increased, a wiring board (circuit board) on which the LSI is mounted is required to have an improved signal transmission capability. The signal transmission means within the signal processing device or between the devices is generally configured in a parallel architecture using a bus of a plurality of channels. Even in a personal computer or a workstation, an ALU, a register, a timer / counter, Functional blocks such as a ROM and a RAM are connected by a bus of 16 to 64 channels.

[0003] However, a parallel architecture requires a large number of wires and connectors. Therefore, further parallelization has been promoted by increasing the number of wiring layers and miniaturization, and the transmission capacity of the bus has been improved.However, due to signal delay and transmission waveform distortion caused by capacitance between wirings and wiring resistance,
Multilayering and miniaturization of wiring are reaching their limits. In addition, electromagnetic noise (EMI: Electr
Logic (Interference) is also a major problem. Therefore, the processing capability of the signal processing device is often limited by the transmission capability of the bus on the wiring board.

In order to overcome the limitations of this electric bus,
An optical connection technology in a system called optical interconnection has been considered. As for optical interconnection, see “Tadaji Uchida, 9th Circuit Packaging Academic Conference, 15C
01, pp. 201-202 "," H. Tomimimur
o, et al. , “Packaging Techn.
ology for Optical Interco
nects ", IEEE Tokyo, No. 33,
pp. 81-86, 1994], Osamu Wada, Electronics Apr. 1993, pp. 195-86. 52-55 ", various forms are proposed depending on the configuration of the system.

Further, in order to perform high-speed arithmetic processing, various parallel processing devices for operating a plurality of CPUs (processors) in parallel have been proposed. As a conventional parallel processing device, a plurality of CPUs are connected to a common bus system, and a group of memories similarly connected to the common bus system are connected to a plurality of CPs.
There is a method shared by U. This shared bus system includes a shared bus, an arbiter circuit that arbitrates an access request from a device connected to the shared bus to arbitrate an access request and permits access, a device that inputs and outputs data to and from a shared memory, and the like. It consists of.

[0006] In order to provide the system with expandability, a system in which a plurality of buses are connected by a bridge has been considered. This connects a plurality of buses to which a plurality of modules are connected. It is also possible to connect a plurality of buses in cascade.

Japanese Unexamined Patent Publication No. Hei 3-204761 discloses a bus connection device used as a shared bus system in a system having a plurality of CPUs or a hierarchical multiprocessor system. The bus connection device detects a request from each processor for access to another processor, connects each processor via a plurality of buses in response to the detected access request, and detects a frequency of use of each bus. Means for simultaneously processing a plurality of tasks by multiplexing buses whose use frequency is equal to or more than a predetermined value.

Japanese Patent Application Laid-Open No. 4-247551 discloses a data transmission system for transmitting data between a transmission device connected to a single bus and a transmission device connected to a duplex bus. The data transmission system includes a single bus transmission circuit for transmitting and receiving data transmitted from a transmission device connected to a single bus, and a dual bus transmission circuit for transmitting and receiving data transmitted from a transmission device connected to a duplex bus. And data relay determination means for determining interruption of data relay from the other when data is relayed from one of the single bus transmission circuit and the duplex bus transmission circuit, and the data transmitted from the single bus and the duplex Determines whether the data transmitted from the bus is normal on a first-come, first-served basis, and transmits the data when the data is normally received. Data can be transmitted quickly without the need for software.

However, in any of the above methods, as long as the system is constituted by an electric bus, only a pair of signal processors can transmit data on one bus at a given time. Even if such a multiplex transmission method is used, there is a limit to speeding up data processing. Further, even if a multiplex bus system is used, only one-to-one communication between modules is multiplexed, and it is necessary to provide a plurality of buses for multiplexing.

On the other hand, Japanese Patent Application Laid-Open No. 6-291749 discloses an SCS using the optical connection technology described above.
A method of connecting a half-duplex bus such as I or GPIB by a full-duplex transmission line using an optical fiber is shown. In this method, a control circuit is provided in a relay device connected to the relay transmission line, and control of blocking / release of a transmission path from the bus side to the relay transmission line side is controlled according to a signal state on the bus side.

[0011]

However, in the method disclosed in Japanese Patent Laid-Open No. 6-291749, a relay device for connecting the buses is required to connect the buses. However, if a relay device is provided in the connection between the optical buses, the optical signal is once converted into an electric signal by the relay device, and the electric signal is further converted into an optical signal. There is a problem that the noise increases, and an element for light / electricity and electric / light conversion is required, thereby increasing the circuit scale.

In addition, when a plurality of optical buses are connected, there is a problem in how to control communication in each optical bus and communication between each optical bus. Japanese Unexamined Patent Publication No. Hei 6-291749 does not describe anything about this point, and the method of Japanese Patent Laid-Open No. Hei 6-291749 cannot simultaneously perform communication in the optical bus and communication between the optical buses. Cannot be processed at the same time.

When connecting a plurality of optical buses, as shown in FIG. 16, an optical bus 1 to which modules M11, M12... M1n are connected, and an optical bus 2 to which modules M21, M22. If simply connected via the optical transmission line 3, since there is no relay device, the optical bus 1 and the optical bus 2 are connected to one bus, and the optical bus 1 and the optical bus 2 cannot be controlled independently.

That is, when the optical bus 1 and the optical bus 2 are independent buses, for example, the module M1 in the optical bus 1
1 and M13 and communication between the modules M21 and M24 in the optical bus 2 can be performed at the same time. However, when the optical bus 1 and the optical bus 2 are connected to one bus, the multiplexing is performed. Without transmission, the modules M11, M13
Between the modules M21 and M24,
It cannot be done at the same time.

Even when multiplex transmission is used, the degree of multiplexing must be increased. That is, when the optical bus 1 and the optical bus 2 are connected to one bus, for example, the optical bus 1
Between the modules M11 and M13 in the optical bus 2, communication between the modules M21 and M24 in the optical bus 2, and
In order to simultaneously perform three communications, that is, communications between the two modules M12 and M23, the multiplicity must be 3 or more.

As the multiplex transmission method of light, wavelength multiplex transmission, time division multiplex transmission, amplitude multiplex transmission, polarization multiplex transmission, and the like, or a combination thereof can be considered. Therefore, it is necessary to provide a light emitting element, a light emitting element driving circuit, an element or a circuit for separating multiplexed signals, and the like, and it is not always easy to realize multiplex transmission.

Therefore, when a plurality of optical buses are connected, it is desirable that communication in the optical bus and communication between the optical buses can be performed simultaneously without increasing the degree of multiplexing.

Therefore, the present invention can perform communication between two optical buses without performing optical / electrical and electrical / optical conversions, and thus without causing a signal delay, and can perform multiplex transmission. The communication in the optical bus and the communication between the optical buses can be performed simultaneously without increasing the severity.

[0019]

An optical bus system apparatus according to the present invention is capable of connecting a plurality of modules for transmitting and receiving optical signals and transmitting and receiving optical signals to and from a first optical bus capable of optically transmitting over a plurality of transmission channels. A second optical bus capable of connecting a plurality of modules and optically transmitting by at least one transmission channel; and a light of the second optical bus among a plurality of optically transmittable transmission channels of the first optical bus. An optical transmission path for transmitting an optical signal between the first and second optical buses through at least one transmission channel that can be transmitted.

In this case, the second optical bus can also be capable of transmitting light through a plurality of transmission channels, and in that case, the optical transmission line is connected to the first optical bus.
And one or more fixed channels among the plurality of optically transmittable transmission channels of the second optical bus,
An optical signal may be transmitted between the first and second optical buses.

[0021]

In the optical bus system apparatus of the present invention configured as described above, communication between two optical buses is performed without performing optical / electrical and electrical / optical conversions, and thus without causing signal delay. And communication between the optical buses and communication between the optical buses can be performed simultaneously without increasing the degree of multiplexing.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment ... FIG. 1] FIG.
1 shows a first embodiment of the optical bus system device of the present invention.

The optical bus system of this embodiment includes optical buses 1 and 2, n modules M11, M12,... M1n are connected to the optical bus 1, and m modules M21, M21, M22 ... M2m are connected.

The optical transmission medium of the optical buses 1 and 2 is not particularly limited as long as optical transmission is possible, and one using an optical fiber coupler, one using a sheet-shaped optical waveguide, or one using free space propagation is used. Things, etc.

The modules M11, M12... M1n and the modules M21, M22.
U, a memory, and the like, each of which includes a light emitting element and a light receiving element and can transmit and receive an optical signal.

The optical bus 1 and the optical bus 2 are connected by the optical transmission line 3 without using a light receiving element and a light emitting element, that is, without performing light / electricity and electric / light conversion. The optical transmission line 3 is not particularly limited as long as optical transmission is possible, and may be one using an optical fiber, one using an optical waveguide, one using free space propagation, or the like.

The optical transmission line 3 is provided with a channel setting section 4 for setting the transmission channel. The channel setting unit 4
As described later, it is configured by a wavelength filter, an optical switch, an optical switching element, a polarization filter, and the like according to the multiplex transmission system.

In the optical bus 1, the modules M11, M12
... Because the bus is connected between M1n, when signal light emitted from one module is received by another module, the received light intensity is at most 1 / n of the emitted light intensity. Similarly, in the optical bus 2, the modules M21, M22,.
Since the bus connection is used, when the signal light emitted from one module is received by another module, the received light intensity is at most 1 / m of the emitted light intensity. for that reason,
When the optical bus 1 and the optical bus 2 are simply connected, for example, the signal light emitted from the module M11 is transmitted to the module M24.
When receiving light at, the received light intensity is at most 1 / m of the emitted light intensity
× n, which is 1 / n of the case of optical transmission in the optical bus 2.

In order to avoid this decrease in the light receiving intensity, the connection between the optical bus 1 and the optical bus 2 is, for example, a one-to-one connection as shown in a specific example described later.

In this embodiment, the optical buses 1 and 2 are
In addition to enabling multiplex transmission, the communication channel between the optical buses 1 and 2 is not fixed to a specific channel. The method of multiplex transmission may be any of wavelength multiplex transmission, time division multiplex transmission, amplitude multiplex transmission, polarization multiplex transmission, etc., as long as it is an optical multiplex transmission system. Further, these multiplex transmission systems may be combined.

As an example, assume that the transmission channels of the optical buses 1 and 2 are two channels, channels 1 and 2. in this case,
For example, in order for module M11 to communicate with module M14, channel 1 is acquired in optical bus 1, and
Communication is performed through channel 1. At this time, the module M12 in the optical bus 1
In order to perform communication with the communication device 21, a vacant channel 2 is acquired and communication is performed through the channel 2. Further, at the same time, in order for the module M22 to communicate with the module M24, the channel 1 is acquired in the optical bus 2 and the communication is performed by the channel 1.

As described above, in this embodiment, the communication in the optical bus 1, the communication in the optical bus 2, and the communication between the optical buses 1 and 2 can be simultaneously performed by the two transmission channels.

In the case of the wavelength division multiplexing transmission system, a certain wavelength λ
1 is set as channel 1 and the other wavelength λ2 is set as channel 2, and the channel setting unit 4 uses the wavelength filter to set λ1 or λ2 according to which of channels 1 and 2 is used for communication between the optical buses 1 and 2. It is assumed that only signal light having a wavelength of λ2 is passed.

In the case of the time division multiplex transmission system, a certain time timing T1 is set to channel 1 and another time timing T2 is set to channel 2 in synchronization with a clock, and the channel setting unit 4 controls the channel 1 by an optical switch. , 2
Is used for communication between the optical buses 1 and 2,
It is assumed that the optical signal is passed only at the time timing of T1 or T2.

In the case of the amplitude multiplex transmission system, a certain threshold A
The channel setting unit 4 determines that the amplitude equal to or less than the threshold value Ath is channel 1 and the amplitude exceeding the threshold value Ath is channel 2.
Depending on which of channels 1 and 2 is used for communication between optical buses 1 and 2, an optical switching element such as an EP allows only optical signals having an amplitude equal to or less than threshold value Ath or an amplitude exceeding threshold value Ath to pass. Shall be.

In the case of the polarization multiplexing transmission system, a certain polarization direction D1 is used as a channel 1 and another polarization direction D2 is used as a channel 2. The channel setting unit 4 uses a polarization filter to set one of the channels 1 and 2 to an optical bus. It is assumed that only the signal light in the polarization direction of D1 or D2 is passed, depending on whether it is for communication between 1 and 2.

FIG. 2 shows a second embodiment of the optical bus system according to the present invention.

In this embodiment, the optical buses 1 and 2 are
Multiplex transmission is enabled, and the communication channel between the optical buses 1 and 2 is fixed to a specific channel. The rest is the same as the first embodiment except for the channel setting unit 4 as described later.

When the communication channel between the optical buses 1 and 2 is not fixed to a specific channel as in the first embodiment, the use efficiency of the optical bus may be reduced. For example,
The transmission channels of the optical buses 1 and 2 are channels 2 and 2
In the optical bus system which is a channel, when the module M12 in the optical bus 1 wants to communicate with the module M21 in the optical bus 2, only the channel 2 is available in the transmission channel of the optical bus 1, and the channel 2 is not used. When the module M12 is already used for communication in the optical bus 2, the module M12 has to wait for communication until a transmission channel becomes available.

On the other hand, when the communication channel between the optical buses 1 and 2 is fixed to a specific channel as in the second embodiment, the communication requests between the optical buses 1 and 2 are sent simultaneously. As long as there is no communication, the communication in the optical bus 1, the communication in the optical bus 2, and the communication between the optical buses 1 and 2 can always be performed at the same time, and the use efficiency of the optical bus can be improved.

As an example, the transmission channels of the optical buses 1 and 2 are assumed to be two channels of channels 1 and 2 and channel 1
Is set for communication between the optical buses 1 and 2. In this case,
For example, the channels M2 and M11
And communicates between modules M via channel 2
When the communication is performed between the modules M12 and M21, the communication can be performed between the modules M12 and M21 by the channel 1 at the same time.

In this example, in the case of the wavelength division multiplexing transmission system, it is assumed that the channel setting unit 4 allows only the signal light of the wavelength corresponding to the channel 1 to pass through the wavelength filter. In the case of the time division multiplex transmission system, the channel setting unit 4 allows the optical switch to pass the optical signal only at the time timing corresponding to the channel 1, and in the case of the amplitude multiplex transmission system, the channel setting unit 4 Means that only an optical signal having an amplitude corresponding to channel 1 is passed by the optical switching element, and in the case of the polarization multiplexing transmission system, the channel setting unit 4 uses a polarization filter to change the polarization direction corresponding to channel 1. It is assumed that only the signal light is passed.

FIG. 3 shows a first example of an arbitration method in the optical bus system according to the present invention. The bus configuration of the optical bus system device is the same as that described in the first or second embodiment.

In this example, the modules M11, M12... M1n connected to the optical bus 1 are connected to the intra-bus arbitration unit 11, and the modules M21, M2 connected to the optical bus 2.
2... M2m are connected to the intra-bus arbitration unit 12, and the intra-bus arbitration units 11 and 12 are connected to the inter-bus arbitration unit 13.
Is controlled.

The modules M11, M12... M1n are sent to the arbitration unit 11 in the bus, and the modules M21, M22... M2m are sent to the arbitration unit 12 in the bus. And a request flag. A plurality of transmission destination module numbers can be specified.

The bus arbitration units 11 and 12 receive the bus request signal, select a request in accordance with the presence / absence of destination contention and the priority of the request, assign a channel, and transmit the channel as an arbitration result signal. The source module number, the destination module number, and the assigned channel number are transmitted to the source module. The intra-bus arbitration units 11 and 12 can allocate channels to a plurality of modules that have been requested at the same time.

When there is a request for communication between the optical buses 1 and 2, the requesting arbitration unit 11 or 12 transmits the request to the inter-bus arbitration unit 13. Bus arbitration unit 13
Receives the request, and transmits a source module number, a destination module number, a request priority, and a request flag to the arbitration unit 12 or 11 in the request destination as a bus request signal.

The request destination arbitration unit 12 or 11 in the bus
In response to the bus request signal, the request is selected and the channel is allocated, and the arbitration result signal includes the source module number, the destination module number, and the assigned channel number, etc. Send to module. The inter-bus arbitration unit 13 transmits a signal of the arbitration result to the requesting bus arbitration unit 11 or 12,
The requesting bus arbitration unit 11 or 12 transmits the arbitration result signal to the transmission source module.

Further, the inter-bus arbitration unit 13 transmits the assigned channel number to the channel setting unit 4, and the channel setting unit 4 sets the transmission channel of the optical transmission line 3 to the assigned channel. The source module starts a bus cycle with the assigned channel.

FIG. 4 shows a second example of the arbitration method in the optical bus system according to the present invention. The bus configuration of the optical bus system device is the same as that described in the first or second embodiment.

In this example, the modules M11, M12... M1n connected to the optical bus 1 and the modules M21, M22... M2m connected to the optical bus 2 are connected to the bus arbitration unit 14. The channel setting unit 4 is controlled.

The modules M11, M12... M1n and the modules M21, M22.
Then, a source module number, a destination module number, a request priority, and a request flag are transmitted as bus request signals. A plurality of transmission destination module numbers can be specified.

In this example, communication within the optical bus 1 and optical bus 2
The bus arbitration unit 14 selects a request and allocates a channel, including communication within the optical bus 1 and communication between the optical buses 1 and 2, and outputs a source module number, a destination module number, and When the channel is allocated, the allocated channel number is transmitted to the transmission source module.

When the bus arbitration unit 14 allocates a channel to a request for communication between the optical buses 1 and 2,
The assigned channel number is transmitted to the channel setting unit 4, and the channel setting unit 4 sets the transmission channel of the optical transmission path 3 to the assigned channel. The source module starts a bus cycle with the assigned channel.

[Example of Multiplex Transmission Combining Polarization Multiplex Transmission and Amplitude Multiplex Transmission: FIGS. 5, 6, 7 to 11] As a multiplex transmission method for the optical buses 1 and 2, for example, polarization multiplex transmission and amplitude Multiplex transmissions can be combined. A specific example in that case is shown below.

(Specific Configurations of Optical Buses 1 and 2 and Optical Transmission Line 3) FIGS. 5 and 6 show specific examples of the optical buses 1 and 2 and the optical transmission line 3 shown in FIGS.

In this example, the optical buses 1 and 2 respectively
On one end face of the optical transmission media 1e, 2e, light input / output sections 1a to 1e are provided corresponding to the modules connected to the optical buses 1, 2.
1d, 2a to 2d are provided, and on the opposite end surfaces 1f, 2f,
It is assumed that connection ports 1g and 2g are provided.
g and 2g are opposed to each other, and the space between the connection ports 1g and 2g is defined as an optical transmission line 3 using free space propagation.

As the optical transmission media 1e and 2e, for example,
A transparent plate made of PMMA (polymethyl methacrylate) is used. Each of the light input / output sections 1a to 1d and 2a to 2d shows the same light input section and light output section for the sake of convenience in the drawing. However, in practice, the light input section and the light output section are separated from each other. It is provided with a stagger. Thereafter, the light input / output sections 1a to 1d, 2
a to 2d each represent a light incident portion as the case may be;
In some cases, it means a light emitting portion.

The signal light incident on each of the light input / output sections 1a to 1d is diffused by a light diffusion section described later, propagates in the optical transmission medium 1e, is reflected by the end face 1f, and is reflected by the light input / output section 1a. To 1d. Similarly, the signal light incident on each of the light input / output units 2a to 2d is diffused by a light diffusion unit described later, propagates in the optical transmission medium 2e, is reflected by the end face 2f, and is reflected by the light input / output unit 2a. To 2d.

FIG. 5 shows that the signal light incident on the light input / output unit 1a is diffused into the optical transmission medium 1e by a light diffusion unit, which will be described later, of the light input / output unit 1a, reflected on the end face 1f, and is input / output. At the same time as light is transmitted from the units 1b to 1d and transmitted through the optical bus 1, the signal light entering the light input / output unit 2a is transmitted to the optical transmission medium 2e by the light diffusion unit described later of the light input / output unit 2a. Is diffused into the inside, is reflected by the end face 2f, and enters and exits the light input / output sections 2b-2
FIG. 3D shows a state where light is transmitted from the optical bus 2 and transmitted through the optical bus 2.

FIG. 6 shows that the signal light incident on the light input / output unit 1d is diffused into the optical transmission medium 1e by a light diffusion unit described later of the light input / output unit 1d, reflected on the end face 1f, and is input / output. At the same time as light transmission from the units 1a to 1c and optical transmission in the optical bus 1 is performed, the signal light incident on the light input / output unit 1a proceeds in the optical transmission medium 1e without being diffused, and is connected to the connection port. 1g, and further enters a light diffusion portion of the connection port 2g of the optical transmission medium 2e to be described later, is diffused in the optical transmission medium 2e, exits from the light input / output portions 2a to 2d, and exits from the optical bus 1. This shows a state where optical transmission to the bus 2 is performed.

The optical transmission media 1e and 2e are PMM
When A is used, light loss occurs in the optical transmission media 1e and 2e, but the loss is not a problem because the transmission distance is as short as several cm.

(Method of polarization multiplex transmission) FIG. 7 shows a method of polarization multiplex transmission in this example.

In this example, arbitration is performed by the method shown in FIG. 4 and control described later is performed by the bus arbitration unit 14. However, arbitration is performed by the method shown in FIG. The control described later may be performed by 11 or 12.

Each module connected to each of the light input / output sections of the optical buses 1 and 2 is provided with a light emitting element drive circuit 21 and a light emitting element 22. An optical switching unit 24 is provided. In this example, the light switching unit 24 includes a polarization direction rotation unit 25 and a polarization beam splitter 26. Each module is provided on a circuit board.

The light emitting element 2 is driven by the light emitting element driving circuit 21.
2 is driven, and the light emitting element 22 obtains reference 0-degree polarized signal light, that is, for example, linearly-polarized signal light perpendicular to the paper surface. The 0-degree polarized signal light is supplied to the polarization direction rotation unit 2.
At 5, the channel setting signal from the bus arbitration unit 14 leaves the polarization at 0 degrees or rotates the polarization by 90 degrees.

Then, the 0-degree polarized signal light passing through the polarization direction rotating unit 25 travels straight through the polarization beam splitter 26 as shown in FIG. The light enters the light diffusion unit 28 of the incident part, is diffused into the optical transmission media 1e, 2e by the light diffusion unit 28, and
The light is reflected by 2f, emitted from the respective light emitting portions of the optical buses 1 and 2, and used for communication in the optical buses 1 and 2 as shown in FIG.

On the other hand, the signal light that has been polarized by 90 degrees through the polarization direction rotating unit 25, that is, for example, the linearly polarized light parallel to the paper surface, as shown in FIG.
The light is reflected and shifted in the polarization beam splitter 26, enters the shifted position with respect to the light diffuser 28 of the corresponding light incident part of the optical buses 1 and 2, and is not diffused and the optical transmission media 1e and 2e. After traveling through the inside, they reach the connection ports 1g and 2g of the end faces 1f and 2f, and are used for communication between the optical buses 1 and 2 as shown in FIG.

For example, as shown in FIG. 8, the polarization direction rotating unit 25 loads a TN (twisted nematic) liquid crystal 33 between the transparent electrodes 31 and 32 and, as shown in FIG. When an OFF voltage is applied between the electrodes 31 and 32, the signal light from the light emitting element 22 in FIG. 7 is transmitted without rotating the polarized light, and as shown in FIG. When the ON voltage is applied,
The polarization of the signal light from the light emitting element 22 is rotated by 90 degrees, and the OFF voltage and the ON voltage are switched by the channel setting signal from the bus arbitration unit 14.

In the case of the polarization multiplex transmission, the connection ports 1g and 2g of the optical buses 1 and 2 as shown in FIG.
With the polarizing filters 1s and 2s and the light diffusing unit 1 respectively.
t, 2t, and the signal light of 90-degree polarization for communication between the optical buses 1 and 2 shown in FIG.
As shown in FIG. 9 (A), the signal light having the polarization of 90 degrees passes through the polarization filter 1 s of the connection port 1 g of the optical bus 1 and is transmitted to the optical bus 2. 6 is made to diffuse into the optical transmission medium 2e of the optical bus 2 as shown in FIG. 6 by being incident on the optical diffusion section 2t of the connection port 2g of the optical bus 1 shown in FIG. , 2
When the 90-degree polarized signal light for communication between the two is transmitted from the optical bus 2 to the optical bus 1, the 90-degree polarized signal light is transmitted as shown in FIG. 9B. By passing through the polarization filter 2s of the connection port 2g of the optical bus 2 and entering the light diffusion unit 1t of the connection port 1g of the optical bus 1,
The light is diffused in the optical transmission medium 1e of the optical bus 1.

(Method of Amplitude Multiplex Transmission) The amplitude multiplex transmission in this example is executed by changing the light intensity of the signal light transmitted from each module by the number of gradations according to the multiplicity. In this case, a channel for amplitude multiplex transmission is set by a channel setting signal from the bus arbitration unit 14 so that signal lights having the same light intensity are not transmitted simultaneously from a plurality of modules connected to the same optical bus.

On the receiving side, the light on which the signal lights incident on the respective light incident portions of the optical buses 1 and 2 are superimposed is transmitted to the optical buses 1 and 2.
2 are emitted from the respective light emitting portions. Each module separates the signal light of each channel from the superimposed signal light based on the channel setting signal from the bus arbitration unit 14, and detects the necessary signal light.

Specifically, when the multiplicity of the amplitude multiplexing transmission is set to 2, the signal light intensity is set to L1 and H1 with respect to the signal level 0 and 1 in the channel 1, and the signal level is set to 0 and 1 in the channel 2 , 1, the signal light intensity is L2, H2. Note that H1 and H2 have different intensities.

When the received signal light is only the signal light of channel 1, the light intensity of the received signal light is L
1, H1 and L2, H2 when the received signal light is only the signal light of channel 2, but the received signal light is a signal light of channel 1 superimposed on the signal light of channel 2. , L1 + L2, L1 + H
2, L2 + H1, H1 + H2.

The L1, L2, L1 + L2, H1, H
The signal light of channel 1 and the signal light of channel 2 are separated from the eight light intensities of 2, L1 + H2, L2 + H1, and H1 + H2. If L1 and L2 are made negligibly smaller than H1 and H2, L1 = L2 = 0 and 0, H
By discriminating the four light intensities of 1, H2, H1 + H2, the signal light of the channel 1 having the light intensities of 0, H1 and
The signal light of channel 2 having the light intensity of 0, H2 can be separated.

One method for changing the light intensity of the signal light is as follows:
As shown in FIG. 7, the light emitting element driving circuit 21 is controlled by the channel setting signal from the bus arbitration unit 14 to change the driving current of the light emitting element 22 and change the light emission intensity of the light emitting element 22.

As another method, as shown in FIG. 10, instead of the light emitting element 22, a light emitting element array 23 in which a plurality of light emitting elements 23a are arranged is used.
The light emitting element drive circuit 21 is controlled by the channel setting signal from 4 to change the number of light emitting elements in the light emitting element array 23 and change the light emission intensity of the entire light emitting element array 23.

On the receiving side, in each module, the signal light emitted from the corresponding light emitting portion of the optical bus is received by the light receiving element, and the analog signal of the output of the light receiving element 41 is received as shown in FIG. The digital signal is converted into a digital signal by the A / D converter 42, and the converted digital signal is supplied to the discrimination circuit 43. The discrimination circuit 43 responds to the light intensity based on the channel setting signal from the bus arbitration unit 14. The signal level is read, the signal of each channel is separated, and a necessary signal is detected.

(Combination of Polarization Multiplexing Transmission and Amplitude Multiplexing Transmission) In the case where the polarization multiplexing transmission has two channels of 0 degree polarization and 90 degree polarization, and the amplitude multiplexing transmission has two channels as in the specific example described above. In addition, multiplex transmission of four channels can be realized.

In this case, the signal light of 0 degree polarization and small amplitude is channel 1, the signal light of 0 degree polarization and large amplitude is channel 2, and the signal light of 90 degree polarization and small amplitude is channel 3. If the signal light having a large amplitude of 90 degrees is used as the channel 4, the 90 degree polarization is used for communication between the optical buses 1 and 2 as shown in FIG. 7B and FIG.
Channels 1 and 2 are used for communication in the optical buses 1 and 2, and channels 3 and 4 are used for communication between the optical buses 1 and 2. Communication can be performed simultaneously.

In this case, though omitted in FIG. 7,
A polarization splitting means is provided in each of the light emitting portions of the optical buses 1 and 2 so that the signal light emitted from the light emitting portion is converted into the 0 degree polarized signal light of the channel 1 or 2 and the signal light of the channel 3 or 4 9.
In each module, the signal light of each polarization is received by a separate light receiving element, and the signal of channel 1 and the signal of channel 1 are respectively obtained by the method shown in FIG. 2 and a signal of channel 3 and a signal of channel 4 so as to detect necessary signals.

[Example of multiplex transmission combining wavelength multiplex transmission and time division multiplex transmission ... FIGS. 5, 6, and 12 to 15] As multiplex transmission methods of the optical buses 1 and 2, for example, wavelength multiplex transmission and Time division multiplex transmission can also be combined. A specific example in that case is shown below.

(Specific Configurations of Optical Buses 1 and 2 and Optical Transmission Path 3) The optical buses 1 and 2 and the optical transmission path 3 shown in FIGS. 1 to 4 combine the above-described polarization multiplexing transmission and amplitude multiplexing transmission. In the same way as in the case of the above, the configuration shown in FIGS. 5 and 6 is adopted.

(Wavelength multiplex transmission method) FIG. 12 shows a wavelength multiplex transmission method in this example.

Note that this example is also a case where arbitration is performed by the method shown in FIG. 4 and control described later is performed by the bus arbitration unit 14. However, arbitration is performed by the method shown in FIG. The control described later may be performed by 11 or 12.

Each module connected to each of the light input / output sections of the optical buses 1 and 2 is provided with a light emitting element drive circuit 21 and two light emitting elements 22a and 22b.
A light switching unit 24 is provided at each light incidence unit. In this example, the light switching unit 24 includes the light emitting elements 22a, 22
2b and the prism 27. Each module is provided on a circuit board.

The light emitting element drive circuit 21 is controlled by the channel setting signal from the bus arbitration unit 14 to obtain, for example, a signal light having a wavelength of 780 nm as the signal light from the light emitting element 22a and the signal light from the light emitting element 22b. As the signal light, for example, a signal light having a wavelength of 850 nm is obtained.

A wavelength filter coated with a multilayer film is provided on the surface of the prism 27 so that light having a wavelength of 780 nm travels straight through the prism 27 and light having a wavelength of 850 nm is reflected inside the prism 27.

As a result, 78 from the light emitting element 22a
The signal light having a wavelength of 0 nm is, as shown in FIG.
The light travels straight through the prism 27, enters the light diffuser 28 of the corresponding light incident part of the optical buses 1 and 2, is diffused into the optical transmission media 1e and 2e by the light diffuser 28, and has end faces 1f and 2f.
Then, the light is emitted from each of the light emitting portions of the optical buses 1 and 2 and used for communication in the optical buses 1 and 2 as shown in FIG.

On the other hand, 85 from the light emitting element 22b.
The signal light having the wavelength of 0 nm is, as shown in FIG.
The light is reflected and shifted in the prism 27, enters the corresponding light incident portion of the optical buses 1 and 2 at the shifted position with respect to the light diffusing portion 28, and is not diffused and the optical transmission media 1e and 2e.
After traveling through the inside, they reach the connection ports 1g and 2g of the end faces 1f and 2f, and are used for communication between the optical buses 1 and 2 as shown in FIG.

In the case of wavelength multiplex transmission, the connection ports 1g, 2 of the optical buses 1, 2 are used as shown in FIG.
g is composed of wavelength filters 1u and 2u and light diffusion units 1t and 2t, respectively, and signal light having a wavelength of 850 nm for communication between the optical buses 1 and 2 shown in FIG. When transmitted to the optical bus 2, FIG.
As shown in (A), the signal light having the wavelength of 850 nm passes through the wavelength filter 1u of the connection port 1g of the optical bus 1 and enters the light diffusion unit 2t of the connection port 2g of the optical bus 2. As shown in FIG. 6, the signal light having a wavelength of 850 nm for communication between the optical buses 1 and 2 shown in FIG. Conversely, when the signal light is transmitted from the optical bus 2 to the optical bus 1, the signal light having the wavelength of 850 nm passes through the wavelength filter 2u of the connection port 2g of the optical bus 2 as shown in FIG. The optical transmission medium 1 of the optical bus 1 is incident on the light diffusing portion 1t of the connection port 1g of the optical bus 1.
e.

(Method of Time Division Multiplexing Transmission) Time division multiplexing transmission in this example is executed by changing the timing of the signal light transmitted from each module with respect to the clock by the number of timings according to the degree of multiplexing. In this case, the channel setting signal from the bus arbitration unit 14 controls the time division multiplexing transmission channel so that the signal light is not transmitted simultaneously from the plurality of modules connected to the same optical bus at the same timing with respect to the clock. Set.

On the receiving side, the light on which the signal lights incident on the respective light incident portions of the optical buses 1 and 2 are superimposed is transmitted to the optical buses 1 and 2.
2 are emitted from the respective light emitting portions. Each module separates the signal light of each channel from the superimposed signal light based on the channel setting signal from the bus arbitration unit 14, and detects the necessary signal light.

Specifically, when the multiplicity of the time division multiplex transmission is set to 2, as shown in FIG. 14, the signal light of channel 1 is transmitted at the rising edge of the clock, and the signal light of channel 2 is It is transmitted at the falling edge of the clock.

On the receiving side, in each module, the signal light emitted from the corresponding light emitting portion of the optical bus and shown as the multiplexed signal light in FIG. As shown, the output signal of the light receiving element 41 is supplied to a detection circuit 44, which detects the signal level at the clock rising or falling timing based on the channel setting signal from the bus arbitration unit 14. Is read, the signal of channel 1 and the signal of channel 2 are separated, and a necessary signal is detected.

(Combination of Wavelength-Division Multiplexing Transmission and Time-Division Multiplexing Transmission) When wavelength-division multiplexing transmission is performed using two channels of a wavelength of 780 nm and 850 nm, and time-division multiplexing transmission is performed using two channels as in the specific example described above. In addition, multiplex transmission of four channels can be realized.

In this case, the signal light having the wavelength of 780 nm at the timing of the rising edge of the clock is supplied to the channels 1 and 78.
A signal light having a wavelength of 0 nm and a clock falling timing is channel 2 and a signal light having a wavelength of 850 nm and a clock rising timing is channel 3 and 850.
Assuming that the signal light having the wavelength of nm and the falling timing of the clock is the channel 4, FIGS.
Since the wavelength of 850 nm is used for communication between the optical buses 1 and 2 as shown in FIG. 7, channel 1 and channel 2 are used for communication in the optical buses 1 and 2, and channel 3 and channel 4 are used for the optical buses 1 and 2. Communication between the optical buses 1 and 2 and communication between the optical buses 1 and 2 can be performed simultaneously for communication between the optical buses.

In this case, though not shown in FIG. 12, a wavelength separating means is provided in each of the light emitting portions of the optical buses 1 and 2 so that the signal light emitted from the light emitting portions is transmitted to the channel 1.
Alternatively, the signal light having a wavelength of 780 nm is divided into the signal light having a wavelength of 780 nm and the signal light having a wavelength of 850 nm of the channel 3 or 4. In each module, the signal light having each wavelength is received by a separate light receiving element. By the method shown in FIG. 15, a signal of channel 1 and a signal of channel 2 are separated, and a signal of channel 3 and a signal of channel 4 are separated to detect a necessary signal.

[Other Embodiments] In the second embodiment, an example of which is shown in FIG. 2, the optical buses 1 and 2 are each capable of multiplex transmission (two channels in the example of FIG. 2).
This is a case where the communication channel between the optical buses 1 and 2 is fixed to a specific channel (channel 1 in the example of FIG. 2).
The communication channel between the optical buses 1 and 2 may be fixed to a specific channel, and only one of the optical buses may be multiplexed.

For example, in an optical bus system in which the frequency of use of the optical bus 2 is lower than that of the optical bus 1, the transmission channels of the optical bus 1 are two channels, channels 1 and 2, and the transmission channel of the optical bus 2 is channel 1 Channel 1 is used for communication between optical buses 1 and 2 as one channel.

In this case, for example, in order for the module M11 to communicate with the module M14, a channel 2 is acquired in the optical bus 1 and communication is performed by the channel 2. At the same time, if the module M12 in the optical bus 1 wants to communicate with the module M21 in the optical bus 2,
If channel 1 is vacant in the optical bus 2, channel 1 can be acquired and communication can be performed through channel 1. At the same time, if the module M22 wants to communicate with the module M24, and if the channel 1 is vacant in the optical bus 2, the module M22 can acquire the channel 1 and communicate with the channel 1.

That is, in this example, communication in the optical bus 1 and any one of communication in the optical bus 2 and communication between the optical buses 1 and 2 can be performed simultaneously.

[0103]

As described above, according to the present invention, the first and second optical buses are connected to each other without depending on the optical bus expansion method for performing the optical / electrical and electrical / optical conversion. Communication between the first and second optical buses can be performed, the configuration is simple,
An extended optical bus system capable of high-speed transmission without signal delay due to optical / electric and electric / optical conversion can be realized.

According to the first, second or third aspect of the present invention, the communication in the first optical bus and the communication in the second optical bus can be performed without increasing the degree of multiplexing. Any one of the communication between the second optical buses can be performed simultaneously, or the communication in the first optical bus, the communication in the second optical bus, and the first and second optical buses Communication between them can be performed simultaneously, and the performance of the entire system can be improved by executing multitasking.

According to the invention of claim 4, communication in the first and second optical buses can be performed independently and simultaneously by arbitration of the first and second arbitration units in the bus. The inter-arbitration unit can perform communication between the first and second optical buses without changing the arbitration in the first and second optical buses by the first and second intra-bus arbitration units.

According to the fifth aspect of the present invention, the bus arbitration unit accepts the requests from the first and second optical buses at the same time, so that the request with the highest priority can be selected, and the use efficiency of the optical bus can be reduced. Can be improved.

According to the sixth aspect of the present invention, it is possible to realize an optical bus system capable of multiplex transmission and expansion of the optical bus and capable of high-speed transmission with improved use efficiency of the optical bus.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of an optical bus system device of the present invention.

FIG. 2 is a diagram showing a second embodiment of the optical bus system device of the present invention.

FIG. 3 is a diagram showing a first example of an arbitration method in the optical bus system device of the present invention.

FIG. 4 is a diagram showing a second example of the arbitration method in the optical bus system device of the present invention.

FIG. 5 is a diagram showing a specific example of first and second optical buses and an optical transmission line connecting them, and a state of optical transmission in the optical bus.

FIG. 6 is a diagram showing a specific example of first and second optical buses and an optical transmission line connecting them, and a state of optical transmission within the optical bus and between the optical buses.

FIG. 7 is a diagram illustrating a specific example of polarization multiplexing transmission.

FIG. 8 is a diagram illustrating an example of a polarization direction rotating unit in FIG. 7;

FIG. 9 is a diagram illustrating a configuration of a connection port in a specific example of polarization multiplexing transmission.

FIG. 10 is a diagram illustrating an example of a method of changing light intensity in the case of amplitude multiplex transmission.

FIG. 11 is a diagram illustrating a configuration example of signal detection in the case of amplitude multiplex transmission.

FIG. 12 is a diagram illustrating a specific example of wavelength division multiplexing transmission.

FIG. 13 is a diagram illustrating a configuration of a connection port in a specific example of wavelength division multiplexing transmission.

FIG. 14 is a diagram illustrating a specific example of time division multiplex transmission.

FIG. 15 is a diagram illustrating a configuration example of signal detection in the case of time division multiplex transmission.

FIG. 16 is a diagram illustrating a possible example of connecting two optical buses.

[Explanation of symbols]

1, 2 optical buses 1a-1d, 2a-2d optical input / output sections 1e, 2e optical transmission medium 1f, 2f end faces 1g, 2g connection ports 1s, 2s polarization filters 1t, 2t optical diffusion sections 1u , 2u ... wavelength filter 3 ... optical transmission path 4 ... channel setting unit M11, M12 ... M1n, M21, M22 ... M2m ... module 11, 12 ... bus arbitration unit 13 ... bus arbitration unit 14 ... bus arbitration unit 21 ... light emission Element driving circuit 22, 22a, 22b Light emitting element 23 Light emitting element array 24 Light switching unit 25 Polarization direction rotating unit 26 Polarized beam splitter 27 Prism 28 Light diffusion unit 41 Light receiving element 42 A / D converter 43 ... Discrimination circuit 44 ... Detection circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 12/46 12/28 (72) Inventor Shinobu Koseki 430 Nakai-cho Sakai, Ashigara-gun, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. In-house (72) Inventor Ken Uemura 430 Sakai Nakai-cho, Ashigara-kami-gun, Kanagawa Prefecture Inside Green Tech Naka Fuji Xerox Co., Ltd. (72) Inventor Keishi Fujimaga 430 Sakai Nakai-cho Sakai-Kamigawa, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. Person Masao Funada 430 Border, Nakai-cho, Ashigagami-gun, Kanagawa Green Tech Nakai Fuji Xerox Co., Ltd. F-term (reference) 5K002 AA01 AA03 BA03 BA31 DA01 DA02 DA03 DA10 5K033 AA01 CA11 CB08 DA05 DA13 DB05 DB19 DB22

Claims (6)

[Claims] A plurality of modules for transmitting and receiving optical signals can be connected, a first optical bus capable of transmitting light via a plurality of transmission channels, and a plurality of modules for transmitting and receiving optical signals can be connected. A second optical bus capable of transmission, and at least one of the plurality of transmission channels capable of optical transmission of the first optical bus, which is a transmission channel capable of optical transmission of the second optical bus, The first,
An optical transmission path for transmitting an optical signal between the second optical buses. 2. The optical bus system device according to claim 1, wherein said second optical bus is also capable of transmitting light through a plurality of transmission channels. 3. The optical bus system device according to claim 2, wherein said optical transmission line is one or more fixed ones of a plurality of optically transmittable transmission channels of said first and second optical buses. An optical bus system device for transmitting an optical signal between the first and second optical buses by a channel. 4. The optical bus system device according to claim 1, wherein said first optical bus arbitrates a request for communication in said first optical bus from a module connected to said first optical bus. An in-bus arbitration unit; a second in-bus arbitration unit for arbitrating a request for communication in the second optical bus from a module connected to the second optical bus; and the first or second A request for communication between the first and second optical buses from a module connected to the optical bus is sent from the first or second bus arbitration unit of the request source to the second or second request destination. 1 arbitration unit in the bus, and the arbitration result of the second or first arbitration unit in the bus of the request destination is transmitted via the arbitration unit in the first or second bus of the request source. An optical bus system device comprising: an inter-bus arbitration unit that transmits data to a module. 5. The optical bus system device according to claim 1, wherein said first optical bus is a module connected to said first optical bus and said first optical bus is a module connected to said second optical bus.
A request for communication in the optical bus, or communication in the second optical bus, or communication between the first and second optical buses,
An optical bus system device that includes a bus arbitration unit that arbitrates. 6. A circuit board, comprising: a first and a second optical bus; a plurality of signal light transmitting sections each of which emits a signal light and emits the signal light from a signal light emitting end; A plurality of signal light receiving units that receive the signal light incident on the signal light incident end are provided; the first and second optical buses are respectively provided on an optical transmission medium and the optical transmission medium; A plurality of light incident portions into which the signal light transmitted from the signal light transmitting portion is incident, respectively, and the signal lights provided to the optical transmission medium, respectively incident on the light incident portions, are diffused into the optical transmission medium. After that, a plurality of light emitting units that emit as signal light to be transmitted to the signal light receiving unit, and provided on the optical transmission medium, the signal light incident on the light incident unit, the other optical bus Connection port that emits as signal light that enters the optical transmission medium DOO has, wherein the first optical bus connection port second connection port of the optical bus, optical bus system device disposed to face each other.