Abstract:
A method for marking an ophthalmic lens according to predetermined patterns includes supplying a plate ( 1 ) provided with engravings ( 4 ), filling the engravings ( 4 ) with marking ink, applying a pad ( 7 ) to the engravings ( 4 ), applying the pad ( 7 ) to the ophthalmic lens ( 5 ). The method involves a stage for pre-preparing the pad ( 7 ) in such a way that at least two movable with respect to each other inking portions ( 12, 13 ) are defined and a transformation stage for modifying the arrangement of the inking portions ( 12, 13 ) which is carried out between the stage for applying the pad ( 7 ) to the plate ( 1 ) and the stage for applying the inked pad to the lens ( 5 ).

Description:
FIELD OF THE INVENTION 
   The invention relates to the general field of marking ophthalmic lenses. 
   It concerns more particularly a method and a device for depositing ink onto an ophthalmic lens in accordance with predetermined shapes. 
   BACKGROUND OF THE INVENTION 
   The fabrication processes generally employed to obtain a finished ophthalmic lens trimmed to the shape of a particular frame typically include steps during which the ophthalmic lens receives markings on its surface. For example, the lens may receive dots or crosses identifying a particular point (for example the optical center of the ophthalmic lens), axis lines (for example to indicate the axis on which astigmatism is corrected), shapes delimiting a particular area (for example near vision area or distant vision area in the case of progressive ophthalmic lenses). Likewise, it may be necessary to effect markings relating to the identification of the ophthalmic lens or other commercial markings. 
   Of the diverse technologies for causing a mark to appear on the surface of an ophthalmic lens, marking with the aid of an inked pad applied to said surface is routinely employed for its low operating cost and its marking accuracy. 
   Thus there are known processes for depositing ink onto an ophthalmic lens during which an ophthalmic lens is disposed on a support in the vicinity of a plate with engravings reproducing the shapes to be printed on the lens, this plate being commonly referred to as a “printing plate”. 
   The printing plate and the ophthalmic lens are both accessible to an elastically deformable pad, generally of silicone. The pad is first applied to the surface of the printing plate after it has been inked (i.e. after the engravings on the printing plate have been filled with ink). The pad is then moved away from the surface of the printing plate, the ink contained in the engravings adhering to the pad to form an inked pad. 
   The inked pad is then applied to the surface of the ophthalmic lens to be marked and the ink disposed in the engravings on the printing plate is then transferred from the pad to the surface of the ophthalmic lens. 
   A method of printing markings on a progressive ophthalmic lens is also known from the document US 2003/0107704. This method deposits on an ophthalmic lens a pattern that includes a graduated portion. 
   This method can therefore be used to print the same pattern on progressive ophthalmic lenses with different characteristics. The graduations are used afterwards to identify particular points specific to each type of lens. 
   Thanks to this method, it is therefore not necessary to have a marking specific to each of the types of progressive ophthalmic lenses. 
   SUMMARY OF THE INVENTION 
   The object of the invention is to improve this type of ophthalmic lens printing method. 
   To this end, the invention is directed to a method of marking an ophthalmic lens according to predetermined patterns, this method including the following steps:
         provision of a plate having engravings reproducing said predetermined patterns according to a first arrangement;   filling of said engravings with a marking ink;   application of a pad to the engravings on said plate so that the ink contained in the engraving adheres to the pad to form an inked pad carrying said patterns according to the first arrangement;   application of the inked pad to an ophthalmic lens, in such a manner as to deposit thereon the ink disposed in accordance with said predetermined patterns;       

   this method being characterized in that it includes a prior step of preparation of the pad so as to delimit at least two inking portions mobile one relative to the other and in that it further includes, between the step of application of the pad to the plate and the step of application of the inked pad to the lens, a transformation step during which the arrangement of the inking portions is modified by relative displacement of said inking portions to determine a second arrangement of said patterns whereby the patterns are deposited on the lens according to the second arrangement. 
   Starting with only one printing plate, such a method enables the printing of different sizes or shapes of patterns by a single application of the pad to the ophthalmic lens, starting from an initial pattern on the printing plate. 
   Thus a single printing plate can be used to print lenses with different characteristics. 
   For example, to each type of progressive ophthalmic lens there corresponds a specific marking in which the marking identifying the distant vision area is positioned very accurately relative to the marking identifying the near vision area. 
   If the “distant vision” marking is carried by one of the portions of the surface of the pad and the “near vision” marking is carried by another portion of the surface of the pad, the relative position of these two markings can be adjusted for each type of ophthalmic lens. 
   Each lens receives the marking that is specific to it and not a universal graduated marking that necessitates a subsequent step of reading the graduations. 
   This method may be implemented with the following preferred features:
         the relative displacement of said inking portions is effected by displacing one of the inking portions using an actuator;   the second arrangement of the patterns is determined by positioning one of the inking portions against abutments;   the method further includes a step of adjustment of said abutments before the positioning of the inking portion;   said step of adjustment of the abutments is effected simultaneously with other steps;   during the step of application of the pad to the engravings, the inking of the pad by all of said engravings is effected.       

   According to one embodiment, the marking method further includes, between the step of filling of the engravings and the step of application of the pad to the engravings, a configuration step during which the arrangement of the inking portions is modified by relative displacement of said inking portions to feature a predetermined inking arrangement of said patterns thanks to which the patterns carried by the inked pad are deposited according to said inking arrangement. 
   During the step of application of the pad to the engravings, the inking of the pad may be effected by only some of said engravings, said inking arrangement of the pad enabling selection of engravings for inking the pad. 
   A method according to this embodiment enables the use of a printing plate having an area with engravings common to different predetermined patterns as well as areas with specific engravings. Before inking the pad, the two inking portions are first positioned relative to each other so that said area with common engravings inks one of the inking portions whereas a chosen specific area inks the other inking portion. 
   After inking, the transformation step enables the pad to reconstitute the predetermined patterns to be applied to a lens. 
   Thus a single printing plate having a common inking area and specific inking areas may be used to deposit on different lenses different patterns having a common area, rather than a multitude of specific printing plates. 
   The invention also consists of a device for marking an ophthalmic lens in accordance with predetermined patterns, this device being adapted to implement the method described above and including:
         a support for receiving a plate with engravings reproducing said predetermined patterns according to a first arrangement;   a support for receiving an ophthalmic lens;   a device for inking the plate;   a pad having an inking surface through which it is adapted to be moved selectively opposite the first support in an inking position or the second support in a marking position;       

   this device being characterized in that the pad includes at least two inking portions mobile the one relative to the other and in that a displacement drive member is provided for displacing said inking portions between the inking position and the marking position, thanks to which the pad is adapted to be inked with said patterns disposed according to the first arrangement, said patterns being adapted to be disposed according to a second arrangement in the marking position. 
   The device may equally be implemented with the following preferred features:
         a first of said inking portions is coupled to a first rigid member and a second of said inking portions is coupled to a second rigid member, the first rigid member and the second rigid member being adapted to be displaced the one relative to the other, and in that said displacement drive member acts on at least one of the rigid members;   the first inking portion is mounted on a fixed support and the second inking portion is mounted on a mobile support;   the mobile support is adapted to be driven by an actuator;   the mobile support is adapted to cooperate with fixed abutments;   the mobile support is adapted to cooperate with mobile abutments;   the first inking portion and the second inking portion are mounted on the same fixed support, the second portion being made from an elastically deformable material and being coupled to a rigid bar mobile relative to said fixed support;   said rigid bar is attached to the fixed support by a ball-joint;   said rigid bar is adapted to be driven by an actuator; and   the first inking portion and the second inking portion are made of silicone.       

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the invention become apparent in the light of the following description of a preferred embodiment given by way of nonlimiting example, description given with reference to the appended drawings, in which: 
       FIG. 1  represents a printing plate seen from above including visible engravings; 
       FIG. 2  is an ophthalmic lens seen from above after markings have been printed on its surface from the  FIG. 1  printing plate; 
       FIG. 3  is a perspective view of a pad according to the invention; 
       FIG. 4  is a view similar to  FIG. 3 , a portion of the pad having been moved away from the rest of the pad; 
       FIG. 5  is an exploded view of the pad from  FIGS. 3 and 4 ; 
       FIGS. 6 and 7  are views from above of a pad according to a different embodiment of the invention, this pad being respectively in a first position and a second position; 
       FIGS. 8 to 11  are diagrammatic profile views showing successive steps of the marking of an ophthalmic lens in accordance with the invention; 
       FIG. 12  is a perspective view of a pad according to an alternative embodiment of the invention; and 
       FIG. 13  is a perspective view of the pad from  FIG. 12  with a portion of the pad moved away from the rest of the pad; 
       FIG. 14  represents, seen from above, a printing plate adapted to implement the method according to another embodiment of the invention; 
       FIG. 15  represents the step of inking of a pad by the  FIG. 14  printing plate; 
       FIG. 16  is a view of the pad from  FIG. 15  after the transformation step. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows the surface of an inking plate  1  intended to cooperate with a pad, this plate being commonly called a “printing plate”. 
   This printing plate  1  has a plane and smooth surface  2  (that visible in this  FIG. 1 ), optionally varnished, and which includes an inking area  3 . 
   In this inking area  3 , engravings  4  are made on the surface  2 . Each pattern visible on the printing plate  1  in  FIG. 1  corresponds to one of these engravings  4  and may be effected, for example, by machining or by a chemical process for removing material. 
     FIG. 2  represents an ophthalmic lens  5  seen from above. This lens is, in the present example, a raw lens that has not yet been trimmed, that is to say machined to the shape of a particular frame, which explains its circular shape. 
   The ophthalmic lens  5  has on one of its faces markings  6  produced with ink and reproducing the disposition of the engravings  4  on the printing plate  1  from  FIG. 1 . The ophthalmic lens  5  has in fact received the markings  6  by the application of a previously inked pad to the inking area  3  of the printing plate  1 , in accordance with the method explained hereinafter. 
     FIG. 3  represents a pad  7  adapted to be inked by the printing plate  1  and to deposit the ink on the lens  5 . 
   The pad  7  includes a support  8  to which is fixed a first pad portion  9  made from an elastically deformable material suitable for printing ink, such as silicone, for example. 
   The pad  7  also includes a second pad portion  10  fixed to a mobile member  11 . 
   The second pad portion  10  is made from the same material as the first portion  9  and the mobile member  11  is made from a rigid material. 
   The first pad portion  9  has a contact surface for its cooperation with the printing plate  1  and the lens  5 , this surface being called the “first surface”  12 . Likewise, the second pad portion  10  has a contact surface called the “second surface”  13 . 
   The first surface  12  and the second surface  13  together form an inking surface  14 . The first pad portion  9  and the second pad portion  10  also have a complementary shape so that, when these two members are placed one against the other (which is the case in  FIG. 3 ), the first surface  12  and the second surface  13  are situated in alignment with each other to form a continuous inking surface  14 . 
   Conversely, in  FIG. 4 , the mobile member  11  having been moved, the second pad portion  10  is moved away from the first pad portion  9  so that here the inking surface  14  is discontinuous. 
   The exploded view of  FIG. 5  shows the mechanism for moving the mobile member  11 . 
   The support  8  is in fact attached to a chassis  15  by a set of spacers  16 . The chassis  15  is thus disposed parallel to and facing the support  8 . 
   On this chassis  15  are disposed two jacks  17 ,  18  each having a mobile rod  19 ,  20  the end whereof is fixed to the mobile member  11 . 
   Note that in this  FIG. 5 , for reasons associated with the arrangement of the exploded view, the mobile member  11  has been represented in two parts separated by a horizontal cut. The mobile member  11  is in reality as shown in  FIG. 3 . It is composed of two parallel walls  21 ,  22  held in face-to-face relationship by two spacers  23  (the imaginary cut of  FIG. 5  is made through the spacers  23 ). 
   The chassis  15  further receives a set of three cams  24  each mounted to turn about an axis perpendicular to the chassis  15 . Two of these cams  24  are adapted to cooperate with one of the edges of the wall  21  whereas the third cam  24  is adapted to cooperate with the adjacent edge of this wall  21 , as in  FIG. 5 . Each of the cams  24  is driven in rotation by a motor (not shown). 
   To the chassis  15  there are further fixed three fixed abutments  25  disposed in the same manner as the cams  24  but on the other side of the wall  21  of the mobile member  11 . 
   The mobile member  11  can therefore be moved between a first extreme position in which the wall  21  is disposed against the fixed abutments  25  and a second extreme position in which the wall  21  is disposed, thanks to the jacks  17 ,  18 , against the cams  24  which form adjustable abutments. 
     FIGS. 6 to 11  relate to a pad according to an embodiment other than that represented in  FIGS. 3 to 5 , only the exterior shapes of the first pad portion  9  and the second pad portion  10  having been modified. The numbering used until now applies also to this embodiment which is functionally identical to the previous one. 
     FIG. 6  shows the pad  7  in a position corresponding to that of  FIG. 3 , the second pad portion  10  being disposed against the first pad portion  9 . 
   The mobile member  11  is then disposed against the fixed abutments  25 . 
   As for  FIG. 7 , it shows the pad  7  in a position corresponding to that of  FIG. 4 , the second pad portion  10  being moved away from the first pad portion  9 . The mobile member  11  is at this time disposed against the cams  24 . 
   The elements described hereinabove operate in the manner indicated hereinafter. 
   In  FIGS. 8 to 11 , the printing plate  1 , the lens  5  and the pad  7  are fitted into a printing machine not shown that is well known in this type of application. 
   The printing plate  1  and the lens  5  are respectively positioned on supports mobile in lateral translation whereas the pad  7  is mobile in vertical translation. 
   Referring to  FIG. 8 , the printing plate  1  is first subjected to the passage of an inking member  26  adapted to fill the engravings  4  of the printing plate  1  with ink. The inking member  26  is a bottomless tank which, when it is pressed against the surface  2  of the printing plate  1 , can contain ink  27 . The rim of the inking member  26  adjacent the printing plate  1  is formed by a doctor blade  28  extending all around the inking member  26 . 
   The inking member  26  is held fixed against the printing plate  1  whereas the latter, from the  FIG. 8  position to the  FIG. 9  position, is moved laterally in translation so that the inking member  26  is disposed in the inking area  3  of the printing plate  1  ( FIG. 8 ) and afterwards on the surface  2  of the printing plate  1  ( FIG. 9 ). This enables the engravings  4  to be filled with ink  27 , after which the ink is wiped from the surface of the inking area  3  by the doctor blade  28  to leave ink only in the engravings  4 . 
   The pad is then lowered onto the inking area  3  ( FIG. 9 ). Note that although in this  FIG. 9  the pad  7  is disposed against the printing plate  1  when it is in its position corresponding to  FIG. 7  it may equally well undergo this operation when it is in the position corresponding to  FIG. 6 . 
     FIG. 10  shows the next step during which the pad  7  is lifted and the printing plate  1  is moved in translation to free the space available under the pad  7 . The pad  7  then has on its first surface  12  and its second surface  13  the inked patterns  29  formed beforehand by the engravings  4  of the printing plate  1  and which have now adhered to the pad  7 .  FIG. 7  shows these inked patterns  29 . 
   The pad  7  with the inked patterns  29  forms an inked pad. This pad may then be adjusted as a function of the relative positions to be imparted to the markings  6  when they are produced on the lens  5 . 
   For example, in the case of  FIGS. 6 and 7 , the printing plate  1  and the pad  7  are such that, during the  FIG. 9  step, a set of inked patterns  29  is disposed on the first surface  12  whereas a single inked pattern  29 , corresponding in our example to the near vision measurement area of a progressive lens, is disposed on the second surface  13 . 
   During the step corresponding to  FIG. 10 , the cams  24  are driven to form abutments such that, when the mobile member  11  is disposed against these abutments, the second surface  13  (and consequently the patterns  29  that it carries) and the first surface  12  (and consequently the patterns  29  that it carries) are in the relative position required for the type of lens  5  concerned. 
   The jacks  17 ,  18  are then operated to place the mobile member  11  against the cams  24  and thereby effect the positioning thereof. 
   Note that the adjustment of the cams  24  may be effected in masked time, for example during the steps corresponding to  FIGS. 8 and 9 . 
   The step of  FIG. 11  corresponds to the printing as such of the patterns on the lens  5 . For this, the lens  5  is moved in translation under the pad  7 , the latter being lowered onto the surface of the ophthalmic lens  5  to deposit thereon the inked patterns  29  that on the lens  5  will become the markings  6  visible in  FIG. 2 . 
   The aptitude of the cams  24  to form mobile abutments as well as the possibility of displacement of the mobile member  11  thus enable the forming on a lens  5  of markings  6  the unitary elements whereof are produced by the engravings  4  on the printing plate  1  but have been adapted as a function of the particular type of lens. 
     FIGS. 12 and 13  relate to an alternative embodiment of the pad  7 . The numbering used hereinabove is retained for elements with the same function. 
     FIG. 12  shows a pad  7  the second pad portion  10  whereof is fixed to the support  8 , like the first pad portion  9 . 
   The second pad portion  10  includes a rigid bar  30  embedded in the material of the second portion  10 . This rigid bar is also articulated in a ball-joint  31  fixed relative to the support  8 . 
   One of the ends of the bar  30  is disposed in the vicinity of the second surface  13  whereas the other of these ends, beyond the ball-joint  31 , is coupled by an articulation  32  to two transverse rigid bars  33  themselves coupled to the rods  19 ,  20  of two jacks fixed to the support  8 . 
   In  FIGS. 12 and 13  only the ends of the rods  19 ,  20  of the actuators are represented for greater clarity. 
   When the pad  7  is in the  FIG. 12  position, its layout corresponds to that of the pad from  FIG. 3 , the rods  19 ,  20  of the jacks being deployed. 
   To move to the configuration corresponding to that of  FIG. 4 , that is to say to move the second surface  13  away from the first surface  12 , the rods  19 ,  20  of the jacks are retracted, which causes pivoting of the bar  30  about the ball-joint  31  and consequently displacement of the end of the bar  30  close to the second surface  13  in the direction away from the first pad portion  9 . 
     FIGS. 14 to 16  show another embodiment of the method according to the invention. 
   A printing plate  34  (see  FIG. 14 ) is first prepared for the inking of a pad  35  (see  FIG. 15 ). This printing plate  34  includes an area A of “common” engravings and areas B, C and D of “specific” engravings. 
   This printing plate  34  applies to three different types of lens respectively a first type of marking corresponding to the common area A associated with the specific area B, a second type of marking corresponding to the common area A associated with the specific area C, and a third type of marking corresponding to the common area A associated with the specific area D. This single printing plate  34  is therefore used to mark different lenses by selecting the specific areas to be associated with a common area. 
   After the passage of an inking member over the printing plate from  FIG. 14  in a similar manner to the previous embodiments, a pad  35  undergoes a configuration phase during which its first portion  36  and its second portion  37  are positioned relative to each other so that the first portion  36  can be inked by the engravings of the area A and the second portion  37  can be inked only by one of the specific areas. In the  FIG. 15  example, this is the specific area C. 
     FIG. 15  illustrates the operation of inking the pad  35 , showing the latter disposed against the printing plate  34 , the engravings of the areas A and C, which are used to ink the pad  35 , being represented in dashed line through the pad  35 . 
   The pad  35 , having undergone successively a configuration step and then an inking step, thereafter undergoes a transformation step terminating in the  FIG. 16  position. 
     FIG. 16  is a view from above of the inked pad  35  (the patterns that it carries being represented in dashed line through the pad  35 ) which, after this transformation step, features a predetermined arrangement of the patterns corresponding to the area A relative to the patterns corresponding to the area C. In this position, the pad  35  may then be applied to an ophthalmic lens in the same way as in the embodiments described hereinabove. 
   As for the example of  FIGS. 15 and 16  relating to the area C, the pad  35  may undergo a configuration step in which the second portion  37  is disposed face-to-face with the area B or D, or any other group of selected engravings on the printing plate  34 , to then become, by virtue of the transformation step, the inked pad  35  of  FIG. 16 , the second portion  37  whereof will in this case carry other patterns. 
   The modularity of the pad  35  being exploited both for inking the pad  35  and for application of the patterns to the ophthalmic lens, a large number of different predetermined markings may be applied to different lenses by the same printing plate  34 . 
   Variant embodiments of the device described may be envisaged without departing from the scope of the invention. In particular, the various elements may be used in a printing machine other than that described with reference to  FIGS. 8 to 11 . Likewise, types of markings  6  other than those described may be produced.