GB2457928A - A device for cleaning an optical compenent - Google Patents

Abstract

A device for cleaning an optical component such as end face of an optical connector, comprises a cleaning unit 2 and a drive unit 4 which are releasably engageable with each other. The cleaning unit comprises a housing 6 from which a cleaning tool 14 projects. The cleaning tool 14 is supported by a bushing 16 independently of the drive unit 4. The drive unit 4 has a motor 60 which drives the operation of the cleaning unit 2. A cleaning yarn is fed from a supply spool 10 over the tip of the cleaning tool 14 and back to a take-up spool 12. At the same time, the cleaning tool 14 is oscillated about its lengthwise axis so that the yarn passing over the tip 20 performs an effective cleaning action on the end face of an optical component. The releasably engageable drive unit includes an output element 68 that cooperates with an input member (26, fig 2) of the cleaning unit.

Description

A device for cleaning an end face of an optical component This invention relates to a device for cleaning an end face of an optical component, which component may particularly, although not exclusively, be an optical fibre transmission cable inserted at one end into a ferrule of a connector.

Optical fibres are commonly used in communication systems. In such systems, it is frequently necessary to make connections between optical fibres, or between an optical fibre and another optical or electro-optical component. Connectors for this purpose comprise connector parts which are engageable with one another to make the connection, and which each receive an optical fibre end provided with a ferrule. The ferrule serves to support the fibre itself in the proper alignment within the connector part.

Optical fibres are extremely thin (less than I Op for single mode fibre) and consequently any dirt on the end face of the ferrule can cause significant signal degradation if the dirt, or even a speck of dust, lies over the end of the optical fibre. Any contamination (dust, oil -frequently from human hands, film residues condensed from vapour in the air, grease, powdery coatings resulting from water or other solvents evaporating, etc.) on the end face of the ferrule into which the fibre is assembled can caused significant signal degradation, as in the basic connector the ends of the fibre (assembled into the ferrule) are polished such that the two fibre ends of the mating connectors can abut.

Roughness on the surface such as dust on the fibre ends or any slight angular misalignment will leave a gap between the cores. This gap will result in a deterioration in optical signal at that point of the network scheme due to deterioration of return loss, insertion loss of the optical interface. Consequently, when making connections between optical fibres, it is essential that ferrule ends be thoroughly cleaned before the connector parts are fitted together. Cleaning the ferrule ends in situ is difficult because the ferrule ends are recessed in the connector parts. Since many of the contaminants are too small to be seen with the naked eye, it is also important that every fibre connector be inspected with a microscope before a connection is made. Such fibre inspection scopes are designed to magnify and display the critical portion of the ferrule where the connection will occur.

There are recognised standards and recommendations for ferrule cleaning, for

example as follows:

Inspection Criteria for SMF Pigtail and Patchcord Connectors _____ ______________ ________ Afloweble Viuible Contr inetaon Z Descrbteon Diameler Non-Re movabJes Smith Widtk5 la Area Neer Core <25 urn None None NRs C 2 urn are Acceptable lb Cladding 25urnto Totelof5NRs<Sum None>Sunt urn None> Sum ______________________ --Epoxy RingZone 120 urn to Any Any 2 ContactDiameter l30umto None> 10 urn None> 10 urn 250 urn ________________________ _________________ 251) urn to 3 Feirule Diameter None> 30 urn Any 400 urn ______________ Acceptance criteria for receptacles Aftowable Defects and Scratches2' Zone Description Diameter Defects (diametefl4" Scratches (wldthl' Is Critical Zone (SM 0 to 25 pm none none Fibers Only) ______________ ________________ ________________ Critical Zone(MM 0 to 66 pm $ c 5 un $ C 3 IUfl FibersOnly) ______________ none>Spm none>3pm lb Cladding Zone 25 to 120 pm any <5 pm none > 3 pm' (SM Fibers Only) 3 from 5.10 pm none> 10 urn' _________________ Cladding Zoner $6 to 120 pm any <5 pm none >3 pm' (MM Fibers Only) 3from5-lOpm none >10 pm' _________________ -Adhelve Zone 120 to 130 pm any __________________ 2 Contact Zone 130 to 250 pm any <20 pm any 3 from 20-50 urn none >50 pm' _________________

Table Nores:

1) When Inspecting after po!istIng or sttile performing gu�tlty assurance of a new connector, a limit of S fine scratcheS (<3 pin) may be set In Zone lb In order to establish that a reliable process is being used by the manufacturer 2) Any contaminants that are removab'e must be cleaned from the end-lace 3) Any defects or scratches that extend across mui(ipe zones are eubect to the most stringent criteria 4) The size of a defect is equal to the largest circle that con comp'etely encompass the defect 5) Defects ore defined as permanent iron-linear features". This Includes cantamln�tiOn, pits, etc. 6) Scratches are defined as "permanent linear features" 7) MT ferrutes (e.g. ribbon) have aIlowabe edge chipping from 115 to 125 pm (see section 4.1.3) 8) Zone 2 criteria does not apply to MT-ferrule or Metallic-ferrule connectors (see section 4.1.3 and 4.1.4) Various forms of connector are available, including PC, APC and UPC, and it is desirable for a cleaning device to be able to clean different connector types and sizes.

Devices are available for cleaning the end faces of optical fibre ferrules when in place in the respective connector parts. For example, W02004/073896 discloses such a cleaning device which comprises a handset into which a cartridge can be inserted. The handset accommodates a motor and a power supply, for example batteries, for driving the motor. The cartridge is provided with a cleaning tool which, when the cartridge is installed in the handset, projects through a nose of the handset for engagement with the ferrule to be cleaned. The nose of the handset thus supports the cleaning tool during a cleaning operation. The cleaning medium itself is a yarn or thread which is fed over the tip of the cleaning tool. In use, the yarn is drawn from a supply spool over the tip of the cleaning tool, and is taken up on a take-up spool. The take-up spool is driven by the motor in the handset through a drive mechanism which is coupled with the output shaft of the motor when the cartridge is inserted into the handset.

The drive mechanism also acts on the cleaning tool to rotate it about its own axis through approximately 1800 in each direction.

The nose of the handset is mounted resiliently on the body of the handset and is configured to cooperate with the respective connector part. When the nose engages the connector part, a micro-switch is closed to supply power to the motor. This actives the yarn feed and the rotation of the cleaning tool so that clean yarn is continuously supplied to the interface between the tip of the cleaning tool and the end face of the ferrule, while being rotated backwards and forwards over the ferrule about the axis of the cleaning tool. Control circuitry for the motor terminates the power supply to the motor after a predetermined operative cycle which may, for example, be less than 5 seconds, during which the cleaning tool may rotate through approximately 180° once in each direction.

The cleaning device disclosed in W020041073896 is ergonomically cumbersome, and consequently difficult to use. The need for the handset to be configured so as to provide a cavity into which the cartridge is inserted means that the handset has to be relatively large. Since connections between optical fibres often need to be made in confined spaces which are densely occupied by optical fibres and other circuit components, the size of the handset can make it difficult to position the cleaning tool accurately in a selected connector part. Also, it is possible for the nose to be resiliently pushed back sufficiently far on contact with the connector part to operate the microswitch and start the motor before the tip of the cleaning tool has properly engaged the end face of the ferrule. Consequently, the cleaning cycle can be initiated too early resulting in inadequate cleaning of the ferrule end face. Furthermore, since cooperation between the nose of the handset and the connector part is required to activate the motor, the device lacks versatility, since the handset may not be appropriate for different styles of connector.

According to the present invention there is provided a device for cleaning an end face of an optical component, the device comprising a cleaning unit having a housing which supports a cleaning tool, a supply reel and a take-up reel for a cleaning yarn which extends over the end of the cleaning tool, the housing accommodating a drive mechanism which is adapted to advance the cleaning yarn and to rotate the cleaning tool to perform a cleaning operation, the device further comprising a drive unit which is releasably engageable with the cleaning unit and accommodates a drive means having an output element which cooperates with an input element of the drive mechanism when the drive unit is engaged with the cleaning unit, the cleaning tool extending from the housing during a cleaning operation without contact with the drive unit.

The present invention thus avoids the need for a handset including a cavity to receive a cartridge. Consequently, the device can be made more compact and lighter in weight.

The drive unit may comprise a housing which is engageable with an opening in the housing of the cleaning unit, for example by way of a snap fit. The wall of the housing of the cleaning unit that defines the opening may have at least one aperture which is engageable with a respective resilient lug of the drive unit.

The drive unit may be configured as a handle of the device. The drive means may be an electric motor, in which case the drive unit may be provided with a manually operable switch for operating the motor. The drive unit may also accommodate a power supply for the motor, for example at least one battery.

The cleaning unit housing may have a partition which divides the interior of the housing into separate compartments, one of which accommodates the supply spool and the other of which accommodates the take-up spool.

The partition may be provided with an aperture for the passage of the cleaning yam.

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example to the accompanying drawings in which: Figure 1 shows a cleaning device with casing parts omitted; Figure 2 shows a cleaning unit of the device of Figurel; Figure 3 shows a drive unit of the device of Figure 1; and Figure 4 shows a yarn guide of the cleaning unit shown in Figure 2.

The cleaning device as shown in Figure 1 comprises a cleaning unit 2 and drive unit 4.

The cleaning unit 2 comprises a housing 6 made up of two generally symmetrical housing parts. Similarly the drive unit comprises a housing 4 made up of two generally symmetrical housing parts 8. In Figures 1 to 3, one of each of the pairs of housing parts 6, 8 is omitted, to expose the internal features of the cleaning device.

The cleaning unit 2 accommodates a supply spool 10 and take-up spool 12 for a cleaning yarn (not shown in the drawings). In the context of the present invention the expression "yarn" is used to designate any suitable filamentary, thread-like or ribbon-like material suitable for cleaning end faces of an optical component.

A cleaning tool 14 is supported by a bushing 16 in the housing 6. The cleaning tool 14 is constituted by a yarn guide which is shown more clearly in Figure 4. The yam guide 14 is an elongate component having an integral gear wheel 18 at one end and an operative tip 20 at the other. The gear wheel 18 has a pair of through holes 22 which are aligned with a pair of diametrically opposite grooves 24 extending the full length of the yarn guide 14.

In use of the cleaning device, yarn is taken from the supply spool 10 through one of the holes 22, along the corresponding groove 24, around the tip 20, down the other groove 24, through the other hole 22 to the take-up spool 12. Thus, it will be appreciated that the yarn projects outwardly slightly from the tip 20 to present a yam surface to the component to be cleaned. The region of the yarn guide 14 near the tip 20 may be provided with a cylindrical sleeve (not shown) which encloses the yarn within the grooves 24 at the thinnest region of the yarn guide 14. This protects the yarn from damage as the tip of the yarn guide 14 is inserted into a connector part for a cleaning operation. The sleeve may be a polymer sleeve which is heat shrunk onto the yarn guide 14.

A drive mechanism is accommodated within the housing 6. The drive mechanism comprises an input gear wheel 26 which, via further gear wheels 28, 30 drives the take-up spool 12 via a toothed periphery 32. A connecting arm 34 is pivotably connected at one end to the take-up spool 12 and pivotably connected at its other end to a crown wheel 36. The crown wheel 36 engages the gear wheel 18 of the yarn guide 14.

The interior of the housing 6 is provided with a partition 38 which defines compartments 40, 42 within the housing 6. The supply spool 10 is situated within the compartment 40, while the take-up spool 12 is situated in the compartment 42. In addition, all of the components of the drive mechanism are situated in the same compartment 42 as the spool 12, the result being that the supply spool 10 is isolated from all other moving components of the cleaning unit 2. This avoids contamination of the fresh cleaning yam on the supply spool 10. The partition 38 has an opening 39 for the passage of the yam. A transparent window 44 is provided in the housing 6 to make the supply spool visible from the outside in order to determine the quantity of yarn remaining on the spool 10. A suitable scale or other indication may be provided on the spool flanks to provide a quantitative indication of the length of yarn remaining, possibly expressed in the number of cleaning operations that can be performed before the yarn runs out. On each side of the supply spool 10 there is a spring 45 which is compressed between the spool 10 and the internal surface of the housing 6 to apply proportional friction to the spool 10 to resist its rotation.

The yam guide 14 has a flange 46. A compression spring 48 is compressed between the flange 46 and an internal wall of the casing 6, so as to bias the tip 20 outwardly of the housing 6. The yarn guide 14 can be pressed inwardly of the housing 6 against the force of the spring 48, this movement being accompanied by sliding of the teeth of the gear wheel 18 along the teeth of the crown wheel 36.

The housing 6 has an opening 50 surrounded by a generally cylindrical extension 52.

The extension 52 has two oppositely disposed rectangular openings 54 (only one visible in Figure 2) and a front opening 56.

The housing 8 of the drive unit 4 is received at one end within the cylindrical sleeve 52.

A pair of resilient lugs (not shown) on the housing 4 are engageable in the openings 54 to retain the drive unit 4 within the sleeve 52. A trigger 58 mounted on the drive unit 4 is exposed through the opening 56.

The drive unit 4 accommodates an electric motor 60 and a pair of batteries 62 serving as the power supply for the motor 60. A microswitch 64 operable by the trigger 58 and a circuit board 66 provided with control circuitry for the motor 60 are also accommodated within the housing 4. Alternatively, the motor 60 may be replaced by a manual drive means, such as a handle.

The output shaft of the motor 60 carries a worm gear 68 which, when the drive unit 4 is engaged with the cleaning unit 2, meshes with the drive gear 26.

Although not shown in the drawings, the housing 6 will be provided with a removable nose piece extending over at least most of the exposed part of the yam guide 14. The tip of the nose piece may be configured to engage a specific style of connector, and a plurality of exchangeable nose pieces may be supplied with the cleaning device to fit a variety of connectors of different styles. Figure 5 shows an alternative embodiment in which provision is made for the nose piece to be mounted resiliently with respect to the housing 6. The fixed bushing 18 of Figures 1 and 2 is replaced by a piston 70 which is slidable in the lengthwise direction of the yarn guide 14 within the housing 6, but fixed against rotation. To enable this, the piston is provided with projections 72 which are received in grooves 74 in the housing 6. A spring 76, of lower spring rate than the spring 48, acts between the piston 70 and a wall 78 of the housing 6, to urge the piston outwardly of the housing 6.

The piston is internally screw threaded at the end facing the tip 20 of the yarn guide 14, so that it can receive a replaceable nose piece. When fitted, the nose piece projects out of the housing through an opening 80 to extend up to or beyond the tip 20. The nose piece may is thus resiliently mounted on the housing 6 so as to be movable from a rest position, in which the nose piece fully or partially encloses the part of the yarn guide 14 which projects from the housing 6, to a retracted position, in which at least the tip 20 is exposed.

For use, the cleaning unit and drive unit 4 are connected together as shown in Figure 1 and the tip 20 of the yarn guide 14 is inserted into a connector so as to bring the portion of the yarn extending across the tip 20 into contact with the end surface of the optical fibre ferrule within the connector. In use of the embodiment of Figure 5, this action pushes the nose piece and the piston 70 back against the action of the spring 76 after the nose piece has contacted the connector, to allow the tip 20 to engage the ferrule in the connector. Eventually the movement of the piston 70 will be arrested by abutment between an internal shoulder (not visible in Figure 5) of the piston 70 and a flange 82 of the yarn guide 14 (see Figure 4). As the device is pressed further into the connector, the spring 48 is compressed so as to create a pre-determined contact force between the yarn and the ferrule end face. The trigger 58 is then depressed to operate the microswitch 64 which starts a cleaning cycle. The motor 60 is energised, causing the take-up spool 12 to rotate via the drive mechanism comprising the gear wheels 59, 26, 28, 30 and the toothed periphery 32. Rotation of the take-up spool 12 draws the yarn over the yarn guide 14 from the supply spool 10. The yarn passes through the opening 39 in the partition 38. By this process the length of yarn contacting the ferrule is constantly renewed so that any contamination of the end face of the ferrule is removed from the vicinity of the ferrule to avoid repeat contamination or abrasion from dust or other particles.

Rotation of the spool 12 is transmitted by the connecting arm 34 to the crown wheel 36 where it is converted into oscillating rotational movement. This movement is transmitted to the gear wheel 18 with the result that the yarn guide 14 is rotated through something less than a full rotation, for example 180 0 in either direction. This motion provides an oscillating rotational wiping action of the yarn on the end face of the ferrule to enhance the cleaning action.

The cleaning cycle is controlled by the control circuitry on the circuit board 66.

Typically, a single part-rotation of the yarn guide 14 in each direction will suffice to achieve adequate cleaning of the end face of the ferrule.

When the supply of yarn on the supply spool 10 is exhausted the cleaning unit 2 is detached from the drive unit 4 and replaced by another cleaning unit 2 having a full supply spool 10. The exhausted cleaning unit may be returned for recycling, since many of the components can be reused provided that the supply spool 10 is replaced by a new spool carrying fresh yarn.

The cleaning unit 2 may be replaceable for different applications. Different connectors may use ferrules of different diameter, and consequently it may be desirable to use yarn guides 14 having different tip diameters. For example ferrules of 2.5mm are common, so for many applications the tip 20 will have a diameter slightly less than 2.5mm so that it will fit within a connector recess containing the ferrule. It is becoming increasingly common for connectors to employ ferrules having a diameter of 1.25mm and consequently the device may also need to be used with a yarn guide 14 having a tip diameter of corresponding size. It is also known for optical fibres to be cabled together in a common jacket in the form of a ribbon. It is therefore desirable to provide yarn guides having a geometry suitable for use with ribbon connectors. This can be achieved simply by fitting to the drive unit 4 a cleaning unit 2 having a yarn guide 14 with the desired characteristics for the operation to be carried out.

Because the cleaning unit 2 does not constitute a cartridge which has to be inserted into an enclosure formed by a handset of the device, the device can be made relatively compact and, as shown in the drawings, can have a slim profile tapering towards the projecting cleaning tool 14. The device is therefore able to access optical connectors easily, even in confined working areas.

As shown in Figure 1, the drive unit 4 is configured as a handle, with the trigger 58 positioned conveniently for operation by a user holding the device by the handle. As shown, the handle projects from the cleaning unit 2 at an angle, for example between 900 and 150°, such as approximately 130°, which provides an ergonomically convenient relationship between the length-wise direction of the drive unit 4 and the axis of the yarn guide 14. However, it will be appreciated that other angular relationships between the drive unit 4 and the cleaning unit 2 may be appropriate. For example the drive unit 4 may be aligned with the axis of the yarn guide 14. The batteries 62 are situated relatively low down on the handle, which lowers the centre of gravity of the device as a whole, making it more comfortable to use.

Although not shown, the central shaft of one or both of the spools 10, 12 may be non-cylindrical in order to assist proper movement of the yarn off and onto the spools.

Thus, for example the shaft may taper from one end to the other. It is envisaged that a device in accordance with the present invention can be used with a yarn of finer denier than is currently used, so enabling a single cleaning unit 2 to perform an increased number of cleans, for example 200 -2500 cleans, before the yarn supply is exhausted.

Claims (11)

1. Claims 1. A device for cleaning an end face of an optical component, the device comprising a cleaning unit having a housing which supports a cleaning tool, a supply spool and a take-up spool for a cleaning yarn which extends over the end of the cleaning tool, the housing accommodating a drive mechanism which is adapted to advance the cleaning yarn and to rotate the cleaning tool to perform a cleaning operation, the device further comprising a drive unit which is releasably engageable with the cleaning unit and accommodates a drive means having an output element which cooperates with an input element of the drive mechanism when the drive unit is engaged with the cleaning unit, the cleaning tool extending from the housing during a cleaning operation without contact with the drive unit.
2. 2. A device as claimed in claim 1, in which the drive unit comprises a housing which is engageable with an opening in the housing of the cleaning unit.
3. 3. A device as claimed in claim 2, in which the drive unit is a snap fit in the opening.
4. 4. A device as claimed in claim 2 or 3, in which the wall of the housing defining the opening has at least one aperture which is engageable by a resilient lug provided on the drive unit.
5. 5. A device as claimed in any one of the preceding claims, in which the drive unit is configured as a handle of the device.
6. 6. A device as claimed in any one of the preceding claims, in which the drive means is an electric motor.
7. 7. A device as claimed in claim 6, in which the drive unit is provided with a switch for controlling operation of the motor.
8. 8. A device as claimed in claim 6 or 7, in which the drive unit accommodates a power supply for the motor.
9. 9. A device as claimed in any one of the preceding claims, in which the housing of the cleaning unit is provided with an internal partition which divides the interior of the housing into separate compartments which respectively accommodate the supply and take-up reels.
10. 10. A device as claimed in claim 8, in which the partition has an opening for the passage of the cleaning yarn.
11. 11. A device for cleaning an end face of an optical component substantially as described herein with reference to, and as shown in, the accompanying drawings.