TECHNICAL FIELD

The present invention relates to a fibreoptic switch which will ⁴ enable one or more of an n number of incoming optofibres to be 5 connected with a respective one of an m number of outgoing optofibres.

PRIOR ART

A switch affords a possibility of disposing connections in an ordered array. In the case of opto techniques, the connections

10 consist of optofibres. Manual installation of these fibres in the absence of any ordered lay-out will ultimately result in an unbelievable bundle of tangled fibres which is almost impossible to unravel or which requires expensive de-installation. Attempts have beenmade to provide mechanical solutions whichwill overcome

15 these problems. One solution has been to arrange incoming and outgoing optofibres perpendicularly to one another in one plane, and to mount raisable and lowerable mirrors or like light deflec¬ ting devices at the points at which the fibre axes intersect one another. The drawback with this solution is that it requires the

20 provision of many optical components of high precision. Attenua¬ tion in signal transmission is also high.

Other solutions attempted with switches of this kind have included arranging the incoming and outgoing optofibres in a matrix system.

The switch includes a plurality of optical dividers each connected 25 to a respective incoming optofibre, a plurality of optical switches disposed at the matrix intersection points, and a v plurality of optical combiners each connected to a respective outgoing optifibre. Each switch includes an optoelectric element, an amplifier and an electrooptic element. Because of the large

30 number of structural components involved, a switch of this kind is expensive and complicated, particularly in the case of large switchs affording many coupling possibilities. The switch also requires a continuous supply of current.

DISCLOSURE OF THE INVENTION

The object of the present invention is to avoid the drawbacks of known switchs by providing an optical switch which is inexpensive and reliable and to which current need only be supplied when a change-over is made, and which is of simple construction. This object is achieved with a switch which includes a matrix block provided with light transmission devices which extend in an n number of rows and m number of columns between an input side and an output side, and in that the incoming optofibres on the input side are each displaceable linearly along a respective row of light transmission devices and the outgoing optofibres on the output side are each displaceable linearly along a respective column of light transmission devices. This arrangement enables incoming optofibres to be displaced respectively along their corresponding rows to a desired column of light transmission devices and an outgoing optofibre in a corresponding column to be displacedto a corresponding row of light transmissiondevices for mutual connection of the selected optofibres.

The light transmission devices arepreferablywaveguides, optical fibres or the like. The incoming and outgoing optofibres are advantageously arranged on slides or like devices capable of being displaced in corresponding guide grooves in the matrix block, said light transmission devices terminating in the bottoms of respective guide grooves.

Each slidewill preferably include a spring-biasedball capable of engaging a recess provided in each guide groove and corresponding to eachrowand column of light transmission devices respectively, so as to enable respective optofibres to be set to their correct positions.

An advantage is affordedwhen the slides can be moved in the guide grooves with the aid of steppingmotors or the like, and, when seen in cross section, the slides will preferably have a trapezoidal configuration with the trapezium base facing towards the matrix

block. The guide grooves are correspondingly configured and the optofibres terminate in the base of the trapezoidal slides.

An optical switch constructed in accordance with the invention t- . provides several advantages. One advantage is that there is no

4 5 need to directly remount the connections, i.e. the optofibres, thereby avoiding tangles. The particular arrangement of a matrix enables the maximum number of coupling possibilities to be obtained, i.e. themaximumpossiblenumberof combinationsbetween inputs and outputs.

10 The use of a wave conductor, optical fibre or the like as the light transmission devices affords the advantage that low attenuation can be achieved in all set-ups.

Because the optofibres are disposed on slides or the like capable of being displaced in corresponding guide grooves in the matrix

15 blocks, there is obtained a very simple mechanical construction. The provision on each slide of a spring-biased ball, which can engage in a recess formed in each guide groove and corresponding to each row and column of light transmitting devices respectively, affords the advantage of enabling respective optofibres to be

20 positioned very accurately.

Because the slides can be displaced in the guide grooves with the aid of stepping motors or the like, and because the slides have a trapezoidal cross-section with thebase facing towards the matrix block and because the guide grooves have a corresponding con- 25 figuration, the optofibres can be accurately positioned with the aid of simple means and the mechanical construction is reliable. No separate means are required to hold the slides in position on the matrix block.

The invention will now be described in more detail with reference 30 to an exemplifying embodiment thereof and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a preferred embodiment of an inventive optical switch,

Figure 2 is a sectional view of one part of the switch illustrated in Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION

Figure 1 illustrates in perspective a preferred embodiment of an inventive optical switch. The switch includes a matrix block 1 having a plurality of light transmission devices 2 which are arranged in n number of rows and m number of columns. For the sake of illustration, only four rows and four columns have been shown on the drawing, although it will be understood that any number of rows and columns may be provided and that the number of rows and columns is only restricted by the size of the switch and by what can be considered reasonable from the aspect of construction. Neither need the rows and columns be of mutually equal numbers, as in the case of the illustrated embodiment, but can be varied independently of one another. The light transmission devices 2 extend through the matrix block 1 from an input side to an output side and consist of waveguides, optical fibres or simply of a hole which extends through thematrix block, provided that the block is narrow.

The incoming optifibres 3 on the input side are arranged on slides 4 which are inserted in guide grooves 5 in the matrix block 1 and which can be displaced therealong. The guide grooves 5 are disposed so that each of said grooves will extend along a respec¬ tive row of the n number of rows of light transmitting devices 2, with the light transmitting devices terminating in the bottom of respective grooves 5. Similarly, the outgoing optofibres 6 on the output side are disposed on slides 7, which are inserted in guide grooves 8 in the matrix block 1 and can be displaced therealong. The grooves 8 are disposed perpendicularly to the grooves 5 and each of the grooves 8 extends along a respective column of the m number of columns of light transmitting devices 2, and the light

transmittingdevices terminate inthebottom of respective grooves 8. When seen in cross-section, the slides 4 and 7 have a trapezoi¬ dal configuration, with the base of the trapezium facing towards the matrix block 1. The guide grooves 5 and 8 have a corresponding configuration, so as to guide and hold the slides positively in the matrix block. Both the incoming and outgoing optofibres 3 and 6 are therewith terminated in the base of the trapezoidal slides.

The aforedescribed arrangement enables connections to be made selectively between the incoming and outgoing optofibres. For instance, the incoming optofibre in row 1 can be moved to the third column and the outgoing optofibre in column 3 can be moved to row 1, so as to connect these two optofibres together. Similarly, remaining optofibres can be moved selectively to desired rows and columns respectively, so as to establish the desired connections.

Movement of the slides, and therewith of the optofibres, to the desired rows and columns can be effected with the aid of stepping motors or the like (not shown) which drive the slides. In order to ensure that the correct setting is obtained, each slide 4 or 7 is provided with a spring-biased ball 9 in the base of the slide, immediately adjacent the optofibre, as illustrated in Figure 2, which is a sectional view of part of a guide groove 5 or 8 in the matrix block and a part of a corresponding slide 4 or 7. Each guide groove 5 or 8 is provided with corresponding recesses 10 in which the spring-biased ball 9 can engage and which are located imme- diately adjacent the mouths of the light transmission devices 2. This arrangement enables movement of respective slides to be accurately controlled, so that the optofibre and the light trans¬ mitting device will be in alignment with one another, therewith to achieve the best possible light transmission and the smallest possible attenuation.

It will be understood that the aforesaid optofibres, both the incoming and the outgoing fibres, may also include groups of optofibres, such as band fibre cable having, for instance, eight fibres, in which case each incoming fibre group can be connected to an outgoing optofibre group.

It will also be understood that the invention is not restricted to the aforedescribed and illustrated embodiment, and that modifica¬ tions can be made within the scope of the following Claims.