WO1997039879A1

WO1997039879A1 - Damage repair

Info

Publication number: WO1997039879A1
Application number: PCT/GB1997/001124
Authority: WO
Inventors: Christopher Davies; Matthew Derek Archer
Original assignee: Belron International N.V.
Priority date: 1996-04-23
Filing date: 1997-04-23
Publication date: 1997-10-30
Also published as: ID16821A; AU2397197A; ZA973486B; GB9608363D0

Abstract

Surface damage or flaws (particularly cracks in vehicle windscreens) are repaired using apparatus having a walled bore which surrounds the surface flaw or damage, and a vacuum port communicating through the wall to the bore permitting a region at or adjacent the open end of the bore to be at least partially evacuated of air/gas. A plunger is movable along the bore to urge filler material (resin or the like) into the damage or flaw. A reservoir holds the filler material, which is subsequently dispensed from the reservoir to be introduced to the surface flaw or damage via a flowpath defined through the plunger.

Description

Damage Repair

This invention relates to damage repair, and in particular repair of damaged surfaces where a high quality finish is required. The invention is particularly adapted for repair of surface flaws or damage in transparent screens, panels, panes or covers such as architectural or vehicle windows, windscreens (windshields) or the like.

When a stone or other debris strikes a vehicle laminated windscreen a conical surface crack or "pock mark" frequently results as a cone shaped piece of glass is caused to separate from one of the glass laminations.

Techniques are known for repairing damaged surfaces such as vehicle windscreens, in which cracks, pits or other flaws are infilled with resin material which subsequently cures to fill the flaw. Finally excess cured resin is removed by abrasion and polishing to give a high quality surface finish. In order to ensure a good optical finish by encouraging full resin penetration into the flaw, it is necessary to remove air from (or "de-gasify") the flaw as far as possible. It is furthermore desirable to remove air bubbles from the resin prior to curing a s far as possible in order to provide a good quality optical finish to the repair. For the repair a resin material is selected which, when cured, has a refractive index closely approximating to the glass being repaired.

Techniques and apparatus for repairing damaged vehicle windscreens are known, for example from US-A-4419305, US-A- 4385015, US-A-4047863, US-A-4826413, US-A-4753693, US-A-5069836, US-A-5156853, US-A-4569808, US-A-565217, and US-A-5234525. US-A- 4419305, US-A-4385015, US-A-4047863, US-A-4826413 and US-A- 4569808 disclose windscreen repair apparatus in which a plunger is movable in a walled bore to force resin into the surface damage, crack or flaw. Means for effecting a partial vacuum in the bore (to partially evacuate the damage, crack or flaw) is utilised in each technique.

Problems exist with such prior art techniques particularly in relation to introducing the resin material into the bore which risks exposure of an operator to the resin material which may be hazardous and harmful to health. Furthermore, application of the correct desired force to the plunger to press the resin home without causing crack propagation or further damage to the windscreen is difficult and relies upon operator skill and experience.

It is an object of the invention to provide a repair technique and apparatus providing increased operator safety and an improved means of introducing filler material to the flawed or damaged surface.

It is a further object of the invention to enable operation of the plunger to be bore closely controlled and gauged, thereby reducing operator influence in the effectiveness of the repair process.

It is a yet further object of the invention to improve de-gasing of the flaw or damage and the applied filler material prior to curing, and also improve the effectiveness of the vacuum suction which effects the de-gasing.

An improved technique and apparatus have now been devised.

According to a first aspect, the invention provides apparatus for repairing surface flaws or damage, comprising:

(a) a walled bore having an open end arrangeable in use to substantially surround a surface flaw or damage, and a vacuum port communicating through the wall to the bore, which port permits a region at or adjacent the open end of the bore to be at least partially evacuated of air/gas;

(b) a plunger movable along the bore; and,

(c) a reservoir for flowable filler material; wherein, the reservoir is arranged to hold the flowable filler material prior to introduction of the flowable filler material to the surface damage or flaw, the filler material subsequently being dispensable from the reservoir to be introduced to the surface flaw or damage via a flowpath defined at least a partially through the plunger. It is preferred that the plunger seals (preferably slidingly seals with) the bore so as to define a sealed region about the surface flaw or damage. It is therefore preferred that seal means is provided between the plunger and the bore.

Desirably, the end of the walled bore is provided with a terminal seal (such as an '0' ring seal or the like) arranged to extend about the surface flaw or damage.

The apparatus is preferably operated such that the substantially sealed region is provided about the surface damage or flaw, followed by at least partially evacuating air/gas from the sealed region prior to introducing filler material into the sealed region to penetrate and thereby repair the surface damage or flaw.

Because the sealed region is evacuated of air prior to the introduction of filler into the chamber, the need to de-gas the flaw solely through the applied filler (which is necessary with known techniques) is removed. This reduces the de-gassing time and ensures maximum de-gassing of the flaw.

Advantageously, the flowpath for the filler material communicates with the interior of the walled bore through the end of the plunger. Preferably at least a portion of the flowpath extends internally through the plunger.

The flowpath desirably comprises injection means actuatable to introduce the filler material into the surface damage or flaw when surrounded by the open end of the walled bore. The injection means advantageously comprises a reservoir for the flowable filler material, the reservoir being defined internally of the plunger.

In a preferred embodiment, the injection means comprises a syringe having a cylinder positioned within the interior of the plunger and a piston movable within the cylinder. The syringe is preferably sealed in a (preferably axial) receiving bore provided in the plunger.

The syringe may carry a pre-determined, dosed, amount of filler material (preferably of a curable fluid resin) . Beneficially, the syringe is arranged to lock with syringe piston fully advanced in the syringe cylinder housing subsequent to dispensing of the filler material. Advantageously, the syringe piston and syringe cylinder housing are provided with complementary engaging locking formations for this purpose.

The filler material may be supplied as a discrete packaged dose, for example contained in a breachable or rupturable container or capsule. The container or capsule would be arranged to rupture or be breached upon actuation of the injection means.

It is believed that a syringe and /or a packaged dose of filler material for use in surface repair and having any or all of the features described may be novel and inventive per se.

It is preferred that the plunger is capable of being advanced along the bore (preferably by means of sliding without substantial axial rotation) from a retracted or partially retracted position to an advanced position in which it is arranged to press the filler material into the damage or flaw.

It is preferred that stop means is provided arranged to hold the plunger relative to the bore in a predetermined partially retracted position, the stop means being arrangeable in a release orientation in which relative movement of the plunger along the bore to the advanced position is permitted.

It is believed that such a feature is both novel and inventive per se. According to a third aspect, the invention therefore provides apparatus for repairing flawed or damaged surfaces, which apparatus comprises a plunger movable along a bore in order to press filler material into the surface damage or flaw, stop means being provided arranged to hold the plunger relative to the bore in a predetermined retracted or partially retracted position, the stop means being arrangeable selectively in a release orientation in which movement of the plunger in the bore to an advanced position for pressing the filler material into the flaw or damage is permitted.

Advantageously, the stop means comprise respective abutment portions of the plunger and associated with the bore. The abutment portions are preferably arranged to engage or abut one another in the retracted position (to inhibit advancement of the plunger in the bore to the advanced position) . The abutment portions are selectively arrangeable in a release configuration in which advancement of the plunger in the bore to the advanced position is permitted.

Desirably, the respective abutment portions of the plunger and associated with the bore are orientable in the release position from the abutment position by means of rotating the plunger about its axis in the bore.

Advantageously, one of either the plunger or the bore is provided with a projection or rib, the other of either the plunger or bore being provided with a slot or keyway dimensioned to receive the projection or rib. In the release position, the plunger is rotationally orientated such that the projection or rib lines up with the keyway or slot permitting relative movement of the plunger along the bore with the rib or projection guided in the keyway or slot.

Desirably, the plunger is arranged to be introduced through the proximal end of the bore and advanced to the partially retracted position in which the plunger and bore are held relative to one another by the stop means.

It is preferred that the plunger is arranged to be advanced along the bore by means of the vacuum pressure acting on the plunger.

It is believed that such an arrangement is novel and inventive per se; accordingly another aspect of the invention provides apparatus for repairing flawed or damaged surfaces which apparatus comprises a plunger movable along a bore to define a sealed region about the flaw and/or to press filler material into the surface damage or flaw, wherein the plunger is arranged to be advanced along the bore by means of vacuum pressure acting on the plunger.

It is preferred that the vacuum is applied via a vacuum port provided in the bore, the vacuum port being at a level below the level of the distal end of the plunger when held in the partially retracted position by the stop means.

It is preferred that the distal end of the bore is surrounded by a suction cup to which a vacuum line is arranged to be connected. Desirably, It is once again believed that such an arrangement is both novel and inventive per se, and accordingly, apparatus comprising a vacuum suction cup for use in repairing surface defects and having a flexible peripheral skirt for engaging the surface and being resiliently collapsible from an expanded configuration, provides a further aspect of the invention.

It is preferred that the flexible skirt is arranged to collapse concertina or bellows fashion such that, in collapsing, the distal end of the bore is drawn into contact with the surface about the flaw or defect.

Advantageously, the surface engaging portion of the peripheral skirt of the suction cup comprises a rim of a frustoconical portion of the skirt. Desirably, as the skirt collapses, the proportion of the frustoconical portion in contact with the surface increases until the frustoconical portion folds to lie substantially flat against the surface.

The invention is particularly suited to repair of surfaces of screens, panels, panes or covers which are transparent (or at least translucent) to light.

It is preferred that, in circumstances where the filler material requires forced curing by means of applied radiation, curing is effected by means of radiation delivery means positioned on the opposite side of the screen to the surface damage or flaw. It is believed that such an arrangement is novel and inventive per se.

The invention will now be specifically described in a preferred embodiment, by way of example only, and with reference to the accompanying drawings in which;

Figure 1 is a schematic sectional representation of apparatus for use in a prior art repair technique;

Figure 2 is a schematic sectional representation of apparatus for use in the technique according to the invention;

Figures 3a and 3b are sectional representations of the apparatus of Figure 2 in consecutive stages of operation (skirt collapsed) ;

Figure 4 is a detailed view of a part of the apparatus shown in Figure 2; Figure 4a is a sectional view along A-A in Figure 4;

Figure 5 is a perspective view of the apparatus of Figures 2 to 4; and

Figure 6 is a perspective view, from the underside of the apparatus of Figures 1 to 5.

Known apparatus 101 comprises a suction cup 102 connected to a vacuum line 103, the suction cup being provided with a central aperture through which a de-gasification chamber 104 is introduced to have a distal portion surrounding the flaw in the surface to be repaired. The de-gasification chamber 104 is provided with a radial vacuum port 105 which communicates with the interior of the suction cup to effect a vacuum in the de- gasification chamber 104 and remove air from the flaw when the proximal end of the de-gasification chamber is sealed. The relatively rigid rim 106 of suction cup 102 is placed on the windscreen 109 with the vacuum pump in operation, with the distal end of de-gasification 104 chamber surrounding the flaw (i.e. the crack or pit) . Before the bore of de-gasification chamber 104 is sealed by plunger 107 (see below) , the reduced pressure (vacuum) in the region inside the suction cup 102 but outside the chamber 104 is sufficient to hold the apparatus in position on the screen. It should be noted that at this stage the proximal end of chamber 104 is open to the atmosphere and the air pressure in the chamber 104 is therefore at atmospheric.

Subsequently, liquid resin is introduced via a pipette through the open proximal end of the de-gasification chamber 104 and flows into the flaw. The chamber is then sealed by introducing a screw threaded plunger 107 into the screw threaded proximal end of the de-gasification chamber. The liquid resin infiltrates the surface flaw whilst vacuum is applied via the suction cup 102 to de-gasify the flaw and resin. After a considerable time period has elapsed (typically five minutes) the plunger 107 is screwed down into the de-gasification chamber to its full extent until the distal face 108 of the plunger abuts the flawed surface pressing the resin fully into the flaw. After a further period of a few minutes has elapsed, the vacuum is switched off and the cup is allowed to re-pressurise. The apparatus is subsequently removed from the surface being treated.

Following this, a plastics cover strip is placed over the liquid filled flaw, and a UV curing lamp applied from above the screen to fully cure the resin. Finally, excess resin is removed by means of an abrasion instrument, and the surface is polished.

Disadvantages exist with the technique described because effective de-gasification of the flaw only takes place when the resin has been applied; it is therefore necessary for air in the flaw to be drawn through the resin for complete de- gasification. Furthermore, the need for manually introducing liquid resin into the de-gasification chamber is unsatisfactory because the liquid resin is often an irritant to operator skin. In addition, it has been found that the vacuum seal of the suction cup at the surface is often unsatisfactory, the pressure within the cup sometimes increasing, or an excessively power rated vacuum pump being needed. A further danger is that of the operator over screwing the plunger in the bore which could result in excess force being applied to the screen resulting in crack propagation.

Apparatus of the general type described above is disclosed in US-A-4419305 and US-A-4385015.

Referring now to Figures 2 onwards, there is shown screen damage repair apparatus l comprising an annular rigid plastics housing 2 provided with an axial bore 3, the distal end of which projects into a cavity defined by a peripheral flexible rubber skirt 4.

A plunger 5 is a push fit in the interior of bore 3 of housing 2, plunger 5 being provided with '0' ring seals 6 to effect a sliding seal between the shaft of the plunger 5 and the interior bore of housing 2. Plunger 5 is provided with an enlarged annular collar portion 7 having, at a peripheral position, a longitudinally extending open ended slot or keyway 8 which is dimensioned to receive a complementary rib 9 projecting inwardly from an enlarged mouth portion 10 of bore 3 in housing 2. The proximal end of plunger 5 is provided with an enlarged knurled head 11. Plunger 5 is also provided with an axial bore within which is sealed (by frictional engagement) the outer housing 12 of a syringe 13. Syringe 13 contains a dosed amount of acrylic resin and is provided with a hand actuatable piston 14.

A vacuum line connection port 15 is provided in the rigid housing 2, a vacuum passage communicating through the housing with a vacuum aperture 16 provided in communication with the region bounded by skirt 4. When skirt 4 is placed on a portion of a screen to be repaired and the vacuum applied, air is removed from the region bounded by skirt 4 which consequently collapses concertina fashion such that rubber stops 25 and the distal end of bore 3 abut the screen. The apparatus is positioned such that when the skirt 4 collapses under the influence of the applied vacuum, the flaw to be repaired is bounded by the open distal end of bore 3 which is provided with a terminal 'O' ring seal 17.

Continued application of the vacuum causes air to be removed from the flaw via a radial de-gassing port 18 in bore 3. The applied vacuum causes plunger 5 to be drawn along bore 3 to a position in which the lowermost shoulder of enlarged collar portion 7 engages with the uppermost surface of rib 9. This engagement holds the plunger 5 in a predetermined position relative to the bore 3, with the distal end of the plunger above the level of the de-gassing port 18 (as shown in figure 3a) . The applied vacuum is maintained with the plunger held in the engaged position to effect substantially complete removal of air from the flaw. It is important to note that the apparatus provides for effective complete de-gassing of the flaw before resin is introduced into the flaw.

With the enlarged neck portion 7 of the plunger 5 remaining in the engaged position with rib 9 the syringe piston 14 is fully advanced in syringe housing 12 to dispense filler resin into the now de-gassed flaw. In preferred apparatus the resin is loaded in piston housing 12 in a discrete rupturable sealed capsule (not shown) , the capsule rupturing to release its contents when syringe piston 14 is advanced. This provides a further degree of separation of the operator from the potentially harmful resin.

Subsequently, head 11 of plunger 5 is rotated about its axis (causing the entire plunger 5 to correspondingly rotate) until slot or keyway 8 in enlarged collar projection 7 lines up with rib 9. The pressure differential between atmospheric/ ambient and the reduced pressure within bore 3 (due to the applied vacuum) then draws plunger 5 further along the housing bore 3 with rib 9 being received in and slidingly guiding, keyway 8. Plunger 5 is drawn along housing bore 3 until shoulder 19 (below head 11) approaches the upper peripheral rim 20 of the mouth of housing 2. In this fully advanced position (as shown in figure 3b) , the distal end face of plunger 5 is level with the distal opening of bore 3 and presses the dispensed resin fully into the flaw to be repaired. A further important feature of the technique is that in actuating plunger 5 to press the resin home into the damage flaw, the operator does not need to gauge whether the plunger has been advanced sufficiently, nor is operator manual force required to advance the piston to the required degree. The operator simply rotates head 11 to line up rib 9 and keyway 8, and the plunger is drawn automatically along the bore 3 of housing 2 under a constant predetermined force applied by the vacuum.

After the plunger has been held in the advanced position for sufficient time to allow the resin to fully penetrate the damage flaw, the vacuum may be allowed to collapse and the apparatus removed from the screen. The repair may then be finished as with prior art techniques, for example, by curing utilising an applied U.V. light source held above the screen and subsequent abrading and polishing to produce a high quality finish. U.V. curing is essential when U.V. curing resins are used to effect the repair, such as U.V. curing aerobic acrylic materials conventionally used in the art and disclosed for example in US-A-4419305, US-A-4385015, US-A-4047863, US-A- 4826413, US-A-4753693, US-A-5069836, US-A-5156853, US-A-4569808, US-A-565217, and US-A-5234525. US-A-4419305, US-A-4385015, US-A- 4047863, US-A-4826413 and US-A-4569808.

Alternatively, the resin may be cured from below the screen using an applied radiation source 9 (typically heat or more preferably light) , with the vacuum and plunger apparatus remaining in position on the outer surface of the screen (preferably with plunger 5 in the fully advanced position) . This is most effective where a non-U.V. curing resin (and therefore non-U.V. radiation) is used because laminated vehicle windscreens, for example, often have an intermediate layer which acts as a barrier to U.V. radiation to an extent. Suitable non- U.V. curing resins are disclosed and discussed for example in the trade journal Adhesives Age (April 1995) ; for example materials commercially available from Dynamax Corporation may be used.

A preferred feature of the apparatus 1 is that the thumb pressure head 21 of syringe piston 14 is provided with "snap-fit" projections 22 arranged to engage with complementary receiving recesses 23 provided on the shield 24 of syringe housing 12 when the syringe piston 14 is in its fully advanced position. This provides a permanent lock to prevent syringe piston 14 subsequently being removed from syringe housing 12, thereby preventing operator exposure to any residue resin remaining in the syringe.

The technique and apparatus described provides the following significant advantages over known apparatus and techniques for repairing damage flaws:

1. It is possible to remove air from the damage flaw to a maximum extent prior to introducing resin into the region of the repair. This provides a repair of improved optical quality finish.

2. Advancement of the plunger is controlled automatically at a predetermined force of application dependant on, and determined by, the applied vacuum pressure. This increases ease of operation and prevents flaw (crack) propagation due to excess force applied to the screen by the plunger. The degree of operation skill required for effective repair is accordingly reduced. 3. Operator exposure to the potentially harmful resin is minimised.

4. Vacuum leakage of air is minimised by the provision of the flexible concertina skirt which is capable of deforming to confirm to the curvature of curved screens and surfaces.

Claims

claims :

1. Apparatus for repairing surface flaws or damage, the apparatus comprising:

(b) a plunger movable along the bore; and,

(c) a reservoir for flowable filler material; wherein, the reservoir is arranged to hold the flowable filler material prior to introduction of the flowable filler material to the surface damage or flaw, the filler material being dispensable from the reservoir to be introduced to the surface flaw or damage via a flowpath defined at least a partially through the plunger.

2. Apparatus according to claim 1, wherein the flowpath for the filler material communicates with the interior of the walled bore through the end of the plunger.

3. Apparatus according to claim 1 or claim 2, wherein a portion of the flowpath extends internally through the plunger from the reservoir.

4. Apparatus according to any preceding claim, wherein the injection means is provided comprising the flowpath and actuatable to introduce the filler material into the surface damage or flaw.

5. Apparatus according to claim 4, wherein the injection means comprises the reservoir for the flowable filler material, the reservoir being provided internally of the plunger.

6. Apparatus according to claim 4 or claim 5, wherein the injection means is carried with the plunger such that the injection means and the plunger are movable together along the walled bore.

7. Apparatus according to any of claims 4 to 6, wherein the injection means comprises a syringe having a cylinder comprising the reservoir positioned within the interior of the plunger and a piston movable within the cylinder.

8. Apparatus according to claim 1 , wherein the syringe is arranged coaxially with the plunger.

9. Apparatus according to claim 7 or claim 8, wherein the syringe is arranged to lock with syringe piston fully advanced in the syringe cylinder subsequent to dispensing of the filler material.

10. Apparatus according to claim 8, wherein the syringe piston and the syringe cylinder carry respective complementary engaging locking formations arranged to lock when the syringe piston is fully advanced in the syringe cylinder.

11. Apparatus according to any preceding claim, wherein the open end of the walled bore is provided with a terminal seal arranged to extend about the surface flaw or damage.

12. Apparatus according to any preceding claim, wherein the plunger moves in sealing contact with the bore such that a substantially sealed region can be defined about the surface flaw or damage by the walled bore proximate the open end thereof, and the end of the plunger.

13. Apparatus according to claim 12, wherein seal means is provided between the plunger and the bore.

14. Apparatus according to any preceding claim, wherein the plunger is capable of being advanced along the bore (preferably by means of sliding without substantial axial rotation) from a retracted or partially retracted position to an advanced position in which it is arranged to press the filler material into the damage or flaw.

15. Apparatus according to claim 14, wherein stop means is provided arranged to hold the plunger relative to the bore in a predetermined partially retracted position, the stop means being arrangeable in a release orientation in which relative movement of the plunger along the bore to the advanced position is permitted.

16. Apparatus according to any preceding claim, wherein the open end of the walled bore is surrounded by a suction cup to which a vacuum line is arranged to be connected.

17. Apparatus according to claim 16, wherein the suction cup comprises a flexible peripheral skirt which is arranged to resiliently collapse from an expanded configuration to a collapsed configuration when vacuum pressure is applied.

18. Apparatus for repairing surface flaws or damage, the apparatus comprising:

(a) a walled bore having an open end arrangeble in use to substantially surround a surface flaw or damage, and a vacuum port communicating through the wall to the bore, which port permits a region at or adjacent the open end of the bore to be at least partially evacuated of air/gas; and,

(b) a suction cup surrounding the open end of the walled bore, the suction cup being connectable to a vacuum line and comprising a flexible peripheral skirt arranged to contact the surface about the flaw to be repaired, the skirt being resiliently collapsible from an expanded configuration to a collapsed configuration when vacuum suction is applied to the space in the interior of the cup.

19. Apparatus according to claim 17 or 18, wherein the flexible skirt is arranged to collapse concertina or bellows fashion such that, in collapsing, the distal end of the bore is drawn into contact with the surface about the flaw or defect.

20. Apparatus according to any of claims 17 to 19, wherein stop means are provided, the stop means being spaced about the walled bore internally of the suction cup so as to engage the surface adjacent the flaw or damage, and thereby stabilise the cup, when the skirt is collapsed.

21. Apparatus according to any of claims 17 to 20, wherein the surface engaging portion of the peripheral skirt of the suction cup comprises a frustoconical rim portion of the skirt, the proportion of the frustoconical rim portion in contact with the surface increasing as the skirt collapses until the frustoconical portion folds to lie substantially flat against the surface.

22. Apparatus according to any of claims 18 to 21, further comprising a plunger movable along the bore.

23. Apparatus according to claim 22, wherein the plunger moves in sealing contact with the bore such that a substantially sealed region can be defined about the surface flaw or damage by the walled bore proximate the open end thereof, and the end of the plunger.

24. Apparatus according to claim 23, wherein seal means is provided between the plunger and the bore.

25. Apparatus according to any of claims 22 to 24, wherein the plunger is capable of being advanced along the bore from a retracted or partially retracted position to an advanced position in which it is arranged to press the filler material into the damage or flaw.

26. Apparatus according to claim 25, wherein stop means is provided arranged to hold the plunger relative to the bore in a predetermined partially retracted position, the stop means being arrangeable in a release orientation in which relative movement of the plunger along the bore to the advanced position is permitted.

27. Apparatus according to any of claims 18 to 26, wherein the open end of the walled bore is provided with a terminal seal arranged to extend about the surface flaw or damage.

28. Apparatus according to any of claims 1 to 17 or claims 22 to 26, wherein the plunger is arranged to be advanced along the bore by means of the pressure differential between atmospheric/ambient pressure and the reduced/vacuum pressure in the interior of the walled bore.

29. Apparatus for repairing surface flaws or damage, the apparatus comprising:

(b) a plunger movable along the bore; wherein, the plunger is arranged to be advanced along the bore by means of pressure differential between atmospheric/ambient pressure and the reduced/vacuum pressure in the interior of the walled bore.

30. Apparatus according to any of claims 1 to 17 or claims 22 to 26, or claim 28 or 29, wherein stop means is provided arranged in a stop orientation to hold the plunger relative to the bore in a predetermined partially retracted position, the stop means being arrangeable in a release orientation in which relative movement of the plunger along the bore to the advanced position is permitted.

31. Apparatus for repairing surface flaws or damage, the apparatus comprising:

(b) a plunger movable along the bore in order to press filler material into the surface damage or flaw; and,

(c) stop means arranged to hold the plunger relative to the bore in a predetermined retracted or partially retracted position, the stop means being arrangeable selectively in a release orientation in which movement of the plunger in the bore to an advanced position for pressing the filler material into the flaw or damage is permitted.

32. Apparatus according to claim 30 or claim 31, wherein the stop means comprise respective abutment portions of the plunger and associated with the bore.

33. Apparatus according to claim 32, wherein the abutment portions are arranged, when the plunger is in a retracted position relative to the bore, to engage or abut one another in an abutment configuration and thereby inhibit advancement of the plunger in the bore.

34. Apparatus according to claim 33, wherein the abutment portions are selectively arrangeable in a release configuration in which advancement of the plunger in the bore from the retracted (or partially retracted) position toward the advanced position is permitted.

35. Apparatus according to claim 34, wherein the respective abutment portions of the plunger and associated with the bore are orientable in the release configuration from the abutment position by means of rotating the plunger about its axis in the bore.

36. Apparatus according to any of claims 30 to 35, wherein one of either the plunger or the bore is provided with a projection or rib, the other of either the plunger or bore being provided with a slot or keyway dimensioned to receive the projection or rib, the projection or rib and the slot or keyway being such that, in the release position, the plunger is rotationally orientated such that the projection or rib lines up with the keyway or slot permitting relative movement of the plunger along the bore with the rib or projection guided in the keyway or slot.

37. Apparatus according to any of claims 30 to 36, wherein the plunger is arranged to be introduced through the proximal end of the bore and advanced to the partially retracted position in which the plunger and bore are held relative to one another by the stop means.

38. Apparatus according to any preceding claim for use in repairing a flaw in, or damage to, a vehicular or architectural window or screen (such as a vehicle windscreen) .

39. Apparatus according to any preceding claim, wherein the filler material comprises a curable resin material.

40. A method of repairing a surface flaw or damage on an obverse face of a transparent or translucent screen or panel, the method comprising applying vacuum suction apparatus to the surface about the flaw or damage so as to draw air/gas from the region of the surface damage or flaw; applying flowable filler material to the location of the flaw or damaged surface before, during, or after drawing air/gas using the vacuum apparatus; and, subsequently curing the filler material using a curing agent; wherein the curing is effected by means of directing curing radiation through the screen or panel from the reverse face of the screen or panel; and, wherein the filler material comprises a non-ultra violet curing material and the curing radiation is substantially non-ultra violet; and/or, wherein the vacuum suction apparatus is maintained in position on the obverse face of the screen or panel whilst curing radiation is directed from the reverse face of the screen or panel.

41. A method according to claim 40, wherein the vacuum suction apparatus comprises apparatus according to any of claims 1 to 39.

42. Apparatus comprising a syringe for dispensing flowable filler material to repair a surface flaw or damage, which syringe comprises a cylinder and a piston movable within the cylinder, the syringe being arranged to lock with the syringe piston fully advanced in the syringe cylinder subsequent to dispensing of the filler material.

43. Apparatus according to claim 42, wherein the syringe piston and the syringe cylinder carry respective complementary engaging locking formations arranged to lock when the syringe piston is fully advanced in the syringe cylinder.