Method and apparatus for the application of a protective film to one face of a series of ophthalmic lenses.

DESCRIPTION

The present invention relates to a method and an apparatus for gluing a protective film on a face of a series of ophthalmic contact lenses or "contact lenses" following the preamble of claims 1 and 6.

In the field of ophthalmic lens manufacturing, it is often necessary to apply an adhesive film on the surface of a lens to protect it against lightning or attacks by foreign bodies, for example during an operation called "blocking" or "fixing" ("glantage") of a lens (operation that consists of fixing a metal block on a face of the lens, by casting a low melting point metal, for the subsequent mounting of the lens on the carrier of a surface finishing machine, a beading machine or a polishing machine for ophthalmic lenses). The application of a protective adhesive film of this type is very particularly recommended in the case of contact lenses of orgaonic matter, but can also be carried out in the case of glass lenses.

To apply the adhesive film on a face of a lens, it is known (from US-A-4 242 162, on which the preambles of claims 1 and 6 are based) to place the lens in a cavity open upwards , on a support that can be displaced vertically in the cavity under the action of a cat or cric. An adhesive tape is then carried manually over the cavity in which the lens is and closes it. An annular mandible is then manually displaced and applies the adhesive tape and holds it against the edge of the cavity opening. The lens holder is then moved vertically upwards by means of the cric, which has the effect of applying the adhesive tape against the upper face of the lens, possibly with the help of vacuum if the cavity was connected to a vacuum pump. The adhesive tape is then manually cut by the operator around the lens with the help of a cutting tool of the "cutter" type. The jaw is then opened manually and the lens is evacuated manually with the adhesive film washer glued on its upper face. All or almost all the operations indicated above were therefore carried out manually and, therefore, at a relatively slow rate. In addition, since the adhesive tape is initially flat and that the face to be protected from the lens usually has a curved surface, it is generally not possible to avoid the formation of folds during the application of the adhesive tape on the face of the lens, in particularly when said face of the lens has a strong curvature (ie a small radius of curvature). Such folds impair the good adhesion of the adhesive tape on the face of the pentilla and the obtaining of a layer of uniform thickness between the lens and the metal block which is subsequently glued on the adhesive film.

The present invention therefore aims to provide a method and an apparatus that allow a protective film to be glued on a face of a series of ophthalmic lenses at a clearly higher rate than with the previously known technique.

Subsidiarily, the present invention also aims to provide an apparatus of the genus indicated above in which the protective film is applied on the face of the lens without creasing, even if said face has a small radius of curvature.

Subsidiarily, the invention also aims to provide an apparatus of the geonero indicated above, capable of applying the protective film on the entire face of the lens to be protected, whatever the diameter of said lens.

The method of the present invention for gluing a protective film on a face of a series of ophthalmic lenses comprises the operations that consist of placing a lens of said series of lenses on a support, in developing a roll of a complex tape formed by a tape adhesive, which has an adhesive face, and by a removable tape covering said adhesive face, and in separating the removable tape from the adhesive tape to allow the application of the adhesive tape on a face of the lens placed on said support, and it was characterized in that it comprises punching a predetermined diameter hole, larger than that of the lens, in the removable tape separated from the adhesive tape, in regrouping the punctured removable tape and the adhesive tape in such a way that a round portion of the adhesive face of the adhesive tape remains exposed through the hole of the punctured removable tape, in passing the punctured removable tape and the adhesive tape between said support and a support buffer, in applying said exposed proportion of the adhesive face of the adhesive tape on a face of the lens placed on the support, by relative displacement of at least one of said supports and buffering towards each other, in cutting the adhesive tape around the peripheral edge of the lens, in evacuating the lens with the cut portion of adhesive tape stuck on the face of said lens and forming said protective film, in evacuating the remaining cut-off portion of the adhesive tape and the punctured removable tape and in repeating the preceding operations for each lens of said series.

Preferably, during the operation of applying the adhesive tape on a face of a lens, the removable tape is punctured in preparation of the operation of applying the adhesive tape on a face of the next lens of said series of contact lenses. In addition, during the operation of applying the adhesive tape on one side of a lens and the operation of cutting the adhesive tape, the complex tape is preferably clamped between two jaws that have aligned circular holes that have an internal diameter corresponding to the diode of the hole punched in the removable tape.

The apparatus for carrying out the process of the present invention is characterized in that it also comprises a first set of ro2

017 538 guiding screws for guiding the complex belt along a predetermined path, a second set of guiding rollers for guiding the removable tape of the belt competes along a loop-shaped path, which separates from said predetermined path and re-melts with this, a punching device placed in the loop path to punch the removable tape, a lens holder located on the side of said predetermined path of the complex tape, on the side of the removable tape, downstream of said loop path, a support buffer located on the other side of said predetermined path in alignment with the lens holder, at least one of said lens and lens holder mounts being mounted mobile support perpendicularly to said predetermined path, at least one drive means coupled to one of said contact lens and buffer supports to press between them the complex belt, a cutting device located in the predetermined path of the complex belt downstream of said loop path, and a drive means acting on the complex tape to move it along said predetermined path.

Preferably, the punching device has a punch and a die having a diameter of the largest existing ophthalmic lenses. Preferably, the cutting device comprises a support mounted with rotational capacity around an axis that is perpendicular to the predetermined path of the complex belt, two cutting blades that are mounted on said support and extend parallel to said axis with equidistance from the east. , and a motor coupled to said support to rotate it with the two cutting blades around said axis. Advantageously, the two cutting blades are adjustable in relation to the axis of rotation of the cutting device.

Other features and advantages of the present invention will excel better during the following description, given by way of example with reference to the accompanying drawings in which:

Figure 1 is a view, partly in side elevation and partly in vertical section, showing an embodiment of the apparatus of the present invention.

Figure 2 is a sectional view showing, on a larger scale, the punching device of the apparatus of Figure 1.

Figure 3 is a view, partly in side elevation and partly in vertical section, showing, on a larger scale, other active elements of the apparatus of Figure 1.

The apparatus of Figure 1, which can be part of a machine for preparing and "blocking" or "fixing" ophthalmic lenses, comprises a developer coil 1 and a winding coil 2, which are mounted with rotational capacity in a frame or chassis 3. The winding coil 2 can be rotated by a motor 4, for example an electric motor whose output shaft 5 is coupled to the drive shaft 6 of the winding coil 2 by means of an appropriate transmission 7, for example a chain transmission .

The developing coil 1 carries a roll 8 of a complex tape 9 formed by an adhesive tape 9a and a removable tape 9b that covers the adhesive face of the adhesive tape 9a. The complex tape 9, which develops from the roll 8, first passes over a first table 11 and then on a guide roller 12 at whose exit the removable tape 9b is separated from the adhesive tape 9a. Next, the removable tape 9b follows a looping path passing successively around the two guide rollers 13 and 14, and the two belts 9a and 9b are regrouped as they pass together between a pair of rollers 15 and 16. Next, the complex belt 9 passes over a second table 17, a short distance from the upper face of this, and then around a guide roller 19, to finally be developed on the winding coil 2. The complex tape 9 can be for example constituted by a tape sold by the company "3M" under the reference "1641".

The apparatus of Figure 1 also includes a punching device 21 (shown in more detail in Figure 2) which is installed in the loop path followed by the removable tape 9b, between the guide rollers 13 and

14. Preferably, the punch 22 and the die 23 of the punching device 21 respectively have an outer diameter and an inner diameter that are somewhat larger than the diameter of the largest existing ophthalmic lenses. For example, the diameter of the punch 22 and the die 23 could be between 85 and 90 mm. For its operation, the punch 22 is coupled to the piston rod 24a of a cric 24, for example a pneumatic cric. Each time the punch 22 is actuated, the washer cut eastward on the tape 9b is ejected by blowing compressed air through a hole 25 drilled in the center of the front face of the punch 22. The hole 25 communicates with a passage 26, which is radially perforated in the punch 22 and which, when occupied, is positioned in the position shown in the left part of Figure 2, in turn communicates with a passage 27 radially perforated in the matrix 23 and connected by a connector 28 and a tube (not shown) to a source of compressed air (not shown).

The apparatus of Figure 1 further comprises a lens holder 29, a support buffer 31 and a cutting device 32. The support 29, on which a lens L can be placed, of which one of the two faces, for example The convex face, should be covered with a protective film, is located under a circular hole 34 (which is best seen in Figure 3) of table 17. The hole 34 has a diameter equal to or slightly larger than the diameter of the holes formed by the punching device 21 on the tape 9b. The lens L can be held on the support 29, for example, by means of a suction device not shown. The support buffer 31 is located above the complex belt 9 and the hole 34. The support 29 or the tampon 31, preferably both, can be moved towards each other as will be seen later, to apply the adhesive tape 9a of the complex tape 9 on the exposed face of the lens L carried by the support 29.

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As this is more particularly visible in Figure 3, the area 17a of the table 17, which borders the hole 34, is slightly raised with respect to the flat upper face of said table, so that it forms a fixed jaw capable of cooperating with a movable jaw 35 to clamp the complex tape during the operation of applying the adhesive tape 9a on the exposed face of the lens L and during the cutting operation of the adhesive tape (operations which will be described later). The mobile jaw 35 has a circular hole 36 which has an inside diameter equal to or slightly larger than that of the hole 34 and which is axially aligned with this. The movable jaw 35 extends between two parallel arms 37 and is fixed to these, one of these arms being only visible in the drawings, and both are pivotally mounted, at one end, around an axis 38. At its other end, the arms 37 are articulated by an axis 39 respectively at the ends of the branches of a U-shaped stirrup 41. The bottom portion of the stirrup 41 is fixed to the cylinder 42 of a cric, for example a cric pneumatic, the piston rod 43 of which is fixed

17. Thus, by operating the cric 42, 43, the mobile jaw 35 can be separated at will of the complex belt 9 to release it and allow its advance, and can be pressed against the fixed jaw 17a to clamp the tape 9.

A carriage 44 (Figure 1) is mobile with respect to the table 17 in a direction parallel to the hole axis 34, as indicated by the double arrow

F. The carriage 44 is coupled to the piston rod 45 of a cric, for example a pneumatic cric, and can be moved between two limit positions defined respectively by adjustable stops 47 and 48. Two detectors 49 and 51 are respectively associated with the stops 47 and 48 and emit a signal when carriage 44 reaches the corresponding lamellar position.

At its lower end, the support 29 is coupled to a shaft 52 that can be rotated in a predetermined angle, in both directions of rotation, by a drive device 53 carried by the carriage 44. The drive device 53 may be constituted for example by a pinán that is fixed to the tree 52 and that meshes with a rack attached to a cric, for example a pneumatic cric. Thus, the support 29 can be displaced between a first position, in which the support 29 and the lens L carried by it are aligned with the hole 34 of the table 37, and a second position, in which the support 29 is separated side of hole 34. The first and second positions of the support 29 can be defined by a protrusion piece 54, which is fixed to one side of the support 29 and which can come into contact with one or the other of two stops (not shown) fixed to the carriage 44 Two detectors (in figure 1 a single detector 55 is visible) are respectively associated with these last two stops and emit a signal when the support 29 is in the corresponding position.

When the carriage 44 is in the position defined by the stop 47 and the support 29 is in the second position (laterally separated from the hole 34 of the table 17), the upper part of the support 29 appears in a window (not shown) provided in The chassis of the device. In this position of the support 29, a lens L may be placed on the support 29 (possibly evacuated from said support) manually or by means of an appropriate transfer device. When the support 29 is in its first position (aligned with the hole 34 of the table 17) and the hill 44 is moved by the cric 46 to the position defined by the stop 48, the lens L previously placed in the support 29 is pressed against the adhesive face of the adhesive tape 9a of the complex tape 9 through the hole 34 of the table 17.

The support pad 31 is designed so that it can adapt to the shape of the exposed surface of the lens L when it is pressed against the adhesive tape 9a and repels the latter against the support pad 31. Although tampoán 31 may have an element of a compressible and elastically deformable material, it is preferably constituted by a tool such as that described in the European patent application of the same applicant, filed on March 11, 1988, under number 88 400577.8 and entitled "Self-adapting tool to the surface of an ophthalmic lens." Briefly stated and as shown in Figure 3, the support pad 31 comprises a support 56 that has a cavity 57 open towards the table 17. Two elastically deformable membranes 58 and 59 are fixed by its peripheral edge to the lataeral walls of the cavity 57 and define between them a space that is filled with an incompressible material, in small grains, for example glass or steel balls 61 having a diameter of approximately 1 mm. Thus, when the lens L and the tape 9a are pressed against the membrane 59, the assembly 58-61 deforms and adapts closely to the adjacent face of the lens L. The assembly 58-61 can then be temporarily stiffened, so that form a rigid support surface by vacuuming a side hole of the support 56 connected by a connector 62 and by a tube (not shown) to a vacuum source (also not shown).

The support 56 of the support buffer 31 is coupled to the lower end of the piston rod 63 of a cric, for example a pneumatic cricket, whose cylinder 64 is fixed to a carriage 65. By driving the cric 63, 64, the support buffer 31 it can be separated at will of the complex tape 9 and of the table 17 and brought into contact with the mobile jaw 35, in the immediate proximity of the non-adhesive face of the tape 9a. The carriage 65 is mounted movable with respect to the chassis 3 and the table 17, for example by means of a ball guide, in a direction parallel to the plane of the table and the path followed by the belt 9.

The cutting device 32 is supported by another carriage 66, which is mounted movable with respect to carriage 65, for example by means of a ball guide, in a direction perpendicular to the plane of the table 17 and the path followed by the tape 9 To the carriage 66 the cylinder 67 of a cric is fixed, for example a pneumatic cricket, whose piston rod 68 is supported by the carriage 65. Thus, by operating the cricket 67, 68, the carriage 66 can move between a high position , in which the dis4

017 538 positive cut 32 is separated from the tape 9, and a low position, in which the cutting device is operative to cut the tape 9. Two stops (not shown) can be provided to define respectively the high and low positions of the car 66. Two detectors 69 and 71 emit signals respectively when car 66 reaches its high position and when it reaches its low position.

The carriage 65 was coupled to the piston rod 72 of a cric, for example a pneumatic cricket, whose cylinder 73 is fixed to the chassis 3. Thus, by driving the cricot 72, 73, the carriage 65 can be moved at will between a first position the limit, in which the support buffer 31 was aligned with the hole 34 of the table 17, and a second position of the limit, in which the cutting device 32 was aligned with said hole 34. Stoppers (not shown) may be provided to define the two aforementioned boundary positions of the car 65. A few detectors may also be provided for emitting signals, respectively when the car 65 reaches the first position and when it reaches its second position.

As shown in Figure 3, the cutting device 32 may comprise a fork 74, in the form of a fork, which was fixed to the lower end of a hollow tree 75 that extends perpendicularly to the table 17. The tree 75 is mounted with possibility of rotation by means of appropriate bearings in a bearing 70 fixed to carriage 66. An tree 76 extends inside the hollow amber 75 and was fixed, at its upper end, to a plate 77, fixed in turn to carriage 66. The shaft 75 and the support 74 can be rotated around the shaft 76 by a motor 78, for example an electric motor. A crenellated pulley 79 fixed to the output shaft of the motor 78 transmits the west rotation movement, by means of a crenellated belt 81, to another crenellated pulley 82 fixed to the hollow shaft 75. At least one cutting blade, preferably two cutting blades 83, constituted for example by scalpel blades, are mounted on the support 74 and extend parallel to the axis of the tree 76 equidistant from said axis. Preferably, the two cutting blades 83 are of adjustable separation with respect to the axis of the amber 76, so that their separation can be adjusted according to the external diode of the lens on which the protective film should be applied. To do this, each of the two cutting blades 83 is fixed to a blade holder 84. A screw 85 is mounted with rotational capacity, at its two ends, by appropriate bearings, on the two branches of the fork-shaped bracket 74. The screw 85 has two threaded parts having reverse passages, each of the two threaded parts being screwed into a corresponding threaded hole of one of the two blade holders 84. A conical pinion 86 is fixed to the screw 85 in its central part and meshes with another conical pinion 87 that is fixed to the fixed shaft 76. Two guide pieces 88 and 89, respectively fixed to the leaf holders 84 prevent them from turning with the screw 85 , however, allowing them to move along said screw. Thus, due to the engagement between the fixed pin 87 and pin 86, when the shaft 75 and the bracket 74 are rotated by the motor 78, the two leaf holders 84 and the leaves 83 associated therewith are approached or separated one of the another followed the direction of rotation of the 78 engine. By having the passages of the two screw threads 85 known values ​​and also having the transmission ratio, which is defined by the two pins 86 and 87 and by the two pulleys 81 and 82, a value also known, it is possible to regulate precisely, whenever desired, the separation between the two cutting blades 83, using as the motor 78 a stepper motor and numerical control. Sensors 91, 92 and 93 allow to control the rotation of the cutting device 32 and the position of the cutting blades 83.

The various detectors described above are electrically connected to a control and control box containing a microprocessor that commands the operation of the apparatus following an operating cycle that will now be described.

The lens holder 29 being in its second position (separated from the hole 34 of the table 17) waiting for a lens, a lens is placed on said support 29, manually, by an operator, or automaotically, by means of a appropriate transfer device. Next, the operator enters the manufacturing code of the lens L on a keypad (not shown), a code that indicates in particular to the microprocessor the value D of the lens diameter, so that the microprocessor can rotate the motor 78 in a revolution number appropriate to regulate the separation of the two cutting blades 83 of the cutting device 32 to a slightly higher value (for example: D + 1mm) than that of the diode of the lens L placed on the support 29. Instead of entering the manufacturing code by means of a keyboard, it was observed that the code could have previously been registered in the lens itself, for example in Shape of a bar code. In the latter case, the device may be equipped with a code reader, which reads the bar code and transmits it to the microprocessor. Then the operating cycle is started by a manual command determined by the operator and / or by a validation signal emitted by a detector (not shown) that can be provided on the support 29 and that emits said validation signal when detects the presence of a lens on the support 29.

Next, the motor 4 is started to move the coil 2 in order to wind the complex belt 9 on it and, consequently, to develop it from the coil 8 of the coil 1. The motor 4 stops when a hole previously formed in the tape 9b of the complex tape 9 by the punching device 21 coincides with the hole 34 of the table 17. For example, the motor 4 can be stopped by the signal emitted by a detector 94 (figure 2) which was supported by the matrix 23 and which was arranged to detect the passage of the rear edge of a hole that has just been formed in the belt 9b by the punching device 21, provided, of course, that the length of the path followed by the tape 9b between the detector 94 and the edge of the

017 538 hole 34 of the table 17 has been conveniently regulated in advance, so that it corresponds to an integer multiple of the distance between the centers of two successive holes formed in the tape 9b by the punching device

21.

At the same time, the support 29 is brought, by the drive device 53, to its first position (aligned with the hole 34 of the table 17). Immediately after stopping the engine 4, the cric 42 is actuated in order to firmly tighten the complex belt 9 between the movable jaw 35 and the fixed jaw 17a. Next, the cric 64 is actuated in order to bring the support buffer 31 to its low position, in contact with the mobile jaw 35. Next, the cric 46 is operated in order to move the carriage 44 and the support 29 towards the top to press the lens L against the round portion of the adhesive face of the adhesive tape 9a, which was exposed through the hole 34 of the lames17 of the tape hole 9b of the complex tape. By doing so, the lens L repels the adhesive tape 9a against the support buffer 31 which, deformed, adapts to the shape of the upper face of the lens L. Since, during this operation, the complex tape 9 was firmly held by the jaws 35 and 17a and since the adhesive tape 9a is of a relatively extensible material, the adhesive tape is applied and glued on the upper surface of the lens L without folds forming on said tape.

During the operation of applying the adhesive tape on the upper face of the lens L, the cric 24 is actuated in order to punch a new hole in the tape 9b.

Then, following a possible mode of operation of the apparatus, the support pad 31 is raised again to its high position by means of the cric 64 and then the carriage 65 is moved to the left (seen in Figures 1 and

3) by means of the cric 73, in order to bring the cutting device 32 in alignment with the hole 34 of the table 17. In this position, the axis of the tree 76 was axially aligned with the axis of the lens carried by the support 29. The cric 67 is then actuated to lower the cutting device whose two blades 83 pass through the adhesive tape 9a. Assuming that the transmission ratio determined by the two pulleys 79 and 82 and by the two conical pins 86 and 87 is equal to 1 and that the passage of the two threads of the screw 85 is equal to 0.5 mm, then the motor 78 in such a way that its output shaft made a half turn and that each of the two cutting blades 83 describes a 180 ° arc for cutting the adhesive tape 9a. Actually, each of the two sheets 83 describes a spiral portion. Indeed, in addition to its rotational movement, each cutting blade moves, under the action of screw 85, by 0.25 mm in the direction of the edge of the lens L. It follows that the washer cut by the sheets 83 in the adhesive tape 9a remains fixed to said tape at two diametrically opposite points of the washer, but this is not harmful since the two fixing points are very small and can easily break into the moment of the evacuation of the lens L with the adhesive washer attached to its upper face.

Next, the cutting device 32 is raised to its high position by means of cric 67 and the carriage 65 is returned by cric 73 to its initial position in which the support pad 31 was aligned with the hole 34 of the table 17. At the same time, the carriage 44 is lowered to its low position by the cric 46, the support 29 is carried by the actuation device 53 to its second position (separated from the hole 34 of the table 17) to allow the evacuation of the lens L, manually or by means of an appropriate transfer device, and the placement of a new lens on the support 29, and the mobile jaw 35 is separated from the complex belt 9 by the cric 42 in order to release said tape. Next, the motor 4 is driven again and the cycle described above begins again with the new lens placed on the support 29.

It followed another mode of operation, which is preferable to the mode of operation described above from the point of view of the duration of the cycle of operation, after the adhesive tape 9a has been applied on the upper face of the lens L in the manner described previously, the vacuum is practiced in the space 95 between the adhesive tape 9a and the membrane 59 of the support buffer 31, in order to keep the lens L under the support pad 31. For this, the movable jaw 35 has a passage 96 connected by a connector 97 and by a tube (not shown) to a vacuum source (also not mounted). Next, the carriage 44 is brought to its low position by the cric 46, which has the effect of lowering the support 29, but the lens L remains supported by the support buffer 31 at the same time under the effect of the adhesive substance of the adhesive tape 9a and under the effect of the vacuum and in the space 95. Next, the support 29 is brought to its second position by the drive device 53 waiting for a new lens. During this time, a transfer device (not shown) is set below hole 34 of table 17 to support the contact lens L. The atmospheric pressure is then restored in space 95 and the support buffer 31 is brought to its high position by cric 64. Next, the carriage 65 is moved to bring the cutting device 32 in alignment with the hole 34 of the table 17 and said cutting device is driven as described above to cut the adhesive tape 9a around the edge of the lens L . After this cutting operation, the cutting device is returned to its high position by cric 67, car 65 is returned to its initial position by cric 73, the contact lens L with the adhesive washer attached to its upper face is evacuated towards another treatment station by the aforementioned transfer device and, finally, the movable jaw 35 is separated from the tape 9 by the cric 42 in order to release said tape. A new operating cycle can then be started with a new lens that is placed on the support 29 during the cutting operation of the adhesive tape 9a by means of the cutting device 32.

A tape end detector 98 (Figure 1) pro6

017 The total stoppage of the device and the issuance of a warning signal, when it detects the end of the tape 9. Under these conditions, a new roll 8 of complex tape 9 is installed in the developing coil 1. At the front end of the complex tape 9 of the new roll 8, the adhesive tape 9a is separated from the removable tape 9b and its front ends are spliced, respectively, with the rear ends, still present on the table 11, of the adhesive tape 9a and the removable tape 9b of the previously used complex tape 9. Furthermore, if, at this time, the winding coil 2 is full, the complex belt 9 is advanced through the apparatus until the new complex tape 9 reaches beyond the guide roller 19. The complex tape 9 is then sectioned, the Complex perforated tape roll presents in the winding coil 2 is evacuated and the front end of the new complex tape 9 is fixed to the winding coil

two. The device is then ready to operate again.

From the foregoing, it is clear that the method and apparatus of the present invention, which have been described above, allow a serial protective film to be glued on ophthalmic lenses, whatever its diameter, without wrinkling of the protective film and with a minimum of human intervention, insofar as the apparatus can be highly automated. In addition, the device can operate at a relatively high rate. Reasonable forecasts follow, the device may treat approximately one hundred and fifty lenses per hour.

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