Patent Publication Number: US-2022226947-A1

Title: Positioning device for cards

Description:
The present invention relates to a positioning device for positioning a flat piece with respect to a treatment device, for instance for presenting a card or passport to a laser for engravement. In particular, the invention relates to a positioning device for positioning a card with respect to a treatment device under multiple angles and positions. Further, it relates to a method for operating the positioning device. 
     Flat pieces such as plastic cards are used in different technical areas and need to be treated in different ways. Cards can be used as passport card or identity card. For example, a card printer can be used to print an image and/or graphical elements on the flat piece, a laser may be used for engraving, the flat piece may be laminated, cured, cut, embossed or otherwise treated. 
     One requirement for performing such treatments and manipulations is an efficient and highly automated manner for handling the cards and for presenting the cards to the treatment devices. In some applications, there is a need of tilting and lifting the card and present it to the treatment device under different angles and positions. When rotating the card with respect to for instance a laser, the axis of the working beam will undergo an offset on the card. 
     It is an object of the invention to avoid the disadvantages of the prior art. 
     This object is solved by a positioning device according to claim  1  and a method of operating such a positioning device according to the independent method claim. Further advantages are defined in the dependent claims. 
     The object of the invention is achieved by a positioning device for rotatably and rectilinearly positioning a flat piece, especially a card, with respect to a treatment unit, preferred a laser, with an axis of treatment comprising a card holder for holding a card in a fixed position, wherein the card holder defines a virtual card surface plane coincident with the surface of a card facing the treatment unit once the card is placed in the card holder and wherein the card holder defines a virtual card center point coincident with the intersection point of the axis of treatment and the virtual card surface plane, a manipulator to which the card holder is attached, wherein the manipulator comprises a cardanic structure or cardanic element with a first axis of rotation and a second axis of rotation and a virtual pivot point being the intersection of the first and the second axis of rotation 
     In a further embodiment there are three linear guides, wherein each linear guide is flexibly attached to the cardanic element at a contact point. 
     In a further embodiment, the virtual pivot point of the cardanic element, the first axis of rotation and the second axis of rotation lie in the virtual card surface plane. 
     The positioning device for rotatably positioning a flat piece, especially a card like an identity card or a passport is a tool for presenting a card to a treatment unit. It comprises a card holder in which a card is received and fixed. Thus, the card holder can be handled in which the card is fixed. The card holder can be automatically picked up and moved around and the card contained in the card holder can be subjected to treatment. Especially, the card can be presented under different angles and positions to the treatment unit, preferred a laser. Thus, the card can be tilted with respect to the working axis of the beam of a laser and can be positioned closer or further away from the laser. Thus, the laser can engrave different areas under different angles and with different distances on the card. 
     The card holder is a mechanical tool for holding a card in a fixed position. Preferably the card holder can clamp the card, comprise elements to hold the card, make use of shifting frame parts to grip the card, etc. Preferably, the card holder is adjustable to fit for different sizes of cards. Preferably, the mechanism to adapt for different sizes of cards is used to hold the card at the same time. 
     The card holder has an opening to receive the card and thus defines a virtual card surface plane coincident with the surface of a card facing the treatment unit once the card is placed in the card holder. This virtual card surface plane is the area in the card holder where the card can be inserted and especially this virtual card surface plane is the plane of the surface of the card once inserted. This plane is confined by the type of cards, especially the thickness of cards to be inserted and by the frame elements of the card holder and is a virtual plane in the card holder. If no card is contained in the card holder, this virtual card surface plane is still defined with respect to the geometry of the card holder and the type of card to be inserted. 
     Further, the geometry of the card holder defines a virtual card center point. This virtual card center point is coincident with the intersection point of the axis of treatment and the virtual card surface plane. The axis of treatment is the axis of the working beam of the treatment unit, especially the working axis of the laser beam of the laser used for engraving. The card holder when attached to the manipulator defines one point of intersection between the working beam of the laser and the virtual card surface plane. Preferably, this point of intersection is the center of the working area on the card. Especially preferred this point of intersection is even the center of the card. It is possible that the working area is only a part of the card, for instance the left upper corner of the card. In such circumstances the intersection point of the axis of treatment and the virtual card surface plane is in the center of this area. If the center of the card or the whole card is going to be processed, it is advantageous to have the intersection point of the axis of treatment and the virtual card surface plane in the geometrical center of the card once inserted and it is preferably the point on the surface of the card facing the treatment unit when the card is presented perpendicular to the working axis of the treatment unit. 
     The positioning device further comprises a manipulator for translating and/or rotating the card holder and thus the card with respect to the treatment unit. By the use of the manipulator it is possible to tilt and rotate the card with respect to the treatment unit, especially with respect to the axis of the working axis of the treatment unit, for instance the axis of the working beam of the laser. 
     The card holder is attached to the manipulator. Thus, the card holder is moved according to the movement of the manipulator. Preferably, the card holder is attached to a gripper of the manipulator. 
     The manipulator comprises a cardanic structure or cardanic element with a first axis of rotation and a second axis of rotation and a virtual pivot point being the intersection of the first and the second axis of rotation. Such a cardanic structure preferably comprises rotational bearings and/or linear guidings and mechanical structures to ensure the movement along the first and second axis of rotation and thus around a virtual pivot point. With the structure of the guiding parts, a virtual cardanic point is achieved. With the cardanic element, a movement of the cardanic element—and insofar also of the connected parts, i.e. the card holder—around the virtual pivot point of the cardanic element is achieved. Thus, it is possible to move the cardanic system around this virtual pivot point thereby tilting the card holder and the position of the card with respect to the axis of treatment, especially the working beam of the laser. This is preferably done for two rotational degrees of freedom, meaning that the third rotational degree of freedom is prevented, at least coupled to another element e.g. the base of the manipulator. 
     The cardanic structure or element is preferably connected to three linear guides. A linear guide is a guide which performs a translational movement in one direction, for instance parallel to the direction of the working axis of the treatment unit or perpendicular to it. 
     Each linear guide is flexibly attached to the cardanic element at a contact point. These contact points are not in a straight line in space. Preferably, the first linear guide is directly connected with the cardanic element. For stability reasons it is also possible that the linear guide has an external linear guiding parallel with the first linear guide. The two other linear guides each are connected via a connecting rod with spherical bearing elements (ball joints) on both ends that connect all three translational degrees of freedom at each rod end, but allow all three rotational degrees of freedom at each rod end. By flexibly attaching the linear guide to the cardanic structure or element, it is possible—when performing a translational movement of the linear guide in z-direction—to allow for a movement of the cardanic element and the card holder around the first axis of rotation and/or the second axis of rotation of the cardanic element. The manipulator is preferably built with three parallel linear guides. Using these pillars makes it possible to move in focus direction (along the working axis of the laser) only or move around one of the angles around x (transport direction) or around y (in plane of card, perpendicular to x) or a combination of angles around xy or a combination of angles and focus. 
     The cardanic element is preferably constructed such that the virtual pivot point of the cardanic element, the first axis of rotation and the second axis of rotation lie in the virtual card surface plane. Thus, the intersection of the first and the second axis of rotation of the cardanic system are on the surface of a card once inserted facing the treatment unit, preferably the laser. With the alignment of the first and second axis of rotation to the (virtual) card surface and the positioning of the card in horizontal (X-Y) direction so that the mid-point of the working area on the card coincides with the optical axis of the laser, the virtual pivot point is placed in the middle of the working area of the card surface. Thus, the centerline of the two axis of rotation have a zero distance to the card surface and the distance between the midpoint of the working area of the card and the laser axis is zero. 
     In a further embodiment, a positioning device is provided, wherein the virtual pivot point is coincident with the virtual card center point. Thus, the virtual cardanic point or virtual pivot point is the virtual card center point, i.e. the center of the card. 
     Further, a positioning device is provided, wherein each linear guide is flexibly attached to the manipulator or preferably the cardanic structure via a spherical bearing element, especially a ball joint. Preferably, the first linear guide is connected with the cardanic element through (another) cardanic coupling which allows two rotational degrees of freedom, but does not allow the third rotational degree of freedom neither the three translational degrees of freedom. For stability reasons it is also preferred that the first linear guide has an external linear guiding parallel to that linear guide. The two other linear guides each are connected via a connecting rod with spherical bearing elements (ball joints) on both ends that connect all three translational degrees of freedom at each rod end, but allow all three rotational degrees of freedom at each rod end. This way of attachment allows for a movement of the linear guides in z-direction and for changing the angle between the linear guides and the cardanic element of the manipulator. 
     The linear guides can be arranged in any angle to each other. Preferably, the linear guides are arranged parallel to each other. With this arrangement it is very simple to realize a movement of the card towards to and away from the treatment device without any compensation for tilting and rotating. Thus, when using a laser the card can easily be positioned in different focus distances. Preferably, the linear guides are driven by controlled actuators like stepper motors, servo motors, linear motors, servo-pneumatics or piezo-motors. 
     Further, a positioning device is provided, further comprising an x-y shifting unit. With the x-y-shifting unit it is possible to move the card holder in the x-y plane, i.e. the plane perpendicular to the working axis of the treatment device. With a x-y shifting unit it is possible to shift the virtual pivot point of the cardanic system in x-y plane. Thus, the virtual pivot point can be placed at any point within the reach of the x-y shifting unit. For example, when treating a card with a laser under different angles it can be experienced that the working area on the card becomes smaller due to an unwanted goniometrically induced horizontal shift Lx(1−cos(alpha)). With the use of a x-y-shifting unit it is possible to cover the entire card or data page by shifting the set-up with the 3 actuators when placed on a x-y shifting unit or x-y-stage. Preferably, this is set up to run automatically, so it is possible to change over to another layout with no delay (from card to card) which brings more flexibility for the end user. Further, with a compensation in the x-y-plane it is possible to eliminate unwanted shift effects when tilting the card holder with respect to the working beam. 
     The x-y-shifting unit is preferably attached to the manipulator and is arranged to move the manipulator. Further, x-y-shifting unit can preferably move the complete setup with document and positioning unit to ensure all layouts can be handled more easily, for instance further different positions of the feature to be engraved on the card. Thus, with the x-y-shifting unit it is possible to change the virtual card center point for a new area to be processed on the same card. 
     Further, a positioning device is provided, further comprising a controller unit for controlling the movement of the linear guides and/or the x-y shifting unit. With a controller unit it is possible to program different optimized movements of the card holder by controlling the linear guides and/or the x-y shifting unit. Thus, it is possible to handle the cards and the tilting of the cards under different angles automatically and speed up the treatment time and throughput of cards. 
     The object of the invention is also achieved by an engraving unit comprising a positioning device according to the invention, a treatment unit, preferably a laser, a card handler and an interface to a transport unit for transporting cards. The interface can comprise an exchanger exchanging the engraved card with a blank card. 
     An engraving unit is a unit which handles the cards and engraves them. The card is fed to the engraving unit by a transport system and taken in by the interface to the transport system. This interface presents the card to the card handler. The card handler ensures the right position of the card to be processed and passes it on to the positioning device in a precise manner. The positioning device positions the card and the card holder with respect to the laser beam during treatment. Afterwards, the card is transferred back through the card handler and the interface to the transport unit. 
     The engravement unit is very sensitive to vibrations. However, the transport system usually is a source of vibrations in a scale to influence the quality of the engraving and this can lead to distortions in the engraved features. Thus, it is preferred to support the engraving unit, i.e. the engrave laser together with the card holder on an isolated base. This base is preferably supported by rubber vibration isolators or dampers. These isolators or dampers preferably have a high compliancy, i.e. preferably they have a low rigidity. Due to this compliancy, the exact position of the isolated base is unknown, even more its position can vary. Thus, the isolated base moves a bit during operation, i.e. it floats with an amplitude in all directions between ±1 and ±2 mm. 
     When looking at the card transportation, there are two steps of transferring a card from the non-isolated world to the isolated base (which floats). The first step is the transfer of a card between the non-isolated world and the isolated base and the second step to connect back with the main transport system. Preferably, there are two solutions to combine the bridging with the exchange function: 
     1. to connect the exchanger to the isolated base. 
     2. to connect the exchanger to the non-isolated world. 
     Thus, in one embodiment the treatment unit is isolated with respect to the transport unit as far as vibrations are concerned and the positioning device is also isolated with respect to the transport unit as far as vibrations are concerned. With this embodiment, the card handler and thus the exchanger is not isolated and the bridging will focus on the transfer of the card from the card handler to the positioning device and back. This is solution  2  as described above. 
     In the other embodiment, the card handler, i.e. the exchanger is also isolated with respect to the transport unit as far as vibrations are concerned. This is solution  1  as described above. With this embodiment, the bridge will focus on the transfer of the card from the transportation unit to the card handler. 
     For both solutions it is preferred to provide the rotator with a mechanical or magnetic lock at 12-o&#39;clock positions to release the card holder, so it can be pulled off in those positions. Further, the rotator has preferably lead-in faces that align the card holder to the rotator when the card holder is put back to the rotator by the aligner or the gripper of the manipulator. 
     With solution  1  it is preferred to also have a mechanical or magnetic lock at the 6-o&#39;clock position and/or provide an aligner at the 6-o&#39;clock position of the rotator of the card handler that pulls off the card holder from the rotator. Further, it is preferred to provide lead in faces that pick up and align the card holder to the main transport when the card holder is pulled off (downwards). Preferably, the down position of the cardholder (at 6-o&#39;clock) is equal to the main transport level, enabling transfer from main transport to card holder and back on. 
     With solution  2  it is preferred to provide lead-in faces on the gripper of the manipulator that align the card holder with the gripper. 
     In one embodiment, the card holder (with the card contained in the card holder) is transferable from the card handler to the positioning device and vice versa. The interface to the transport unit transfers a card from the transport unit to the card holder. The card holder is preferably attached to the rotator of the card handler. Preferably, there is provided a mechanical or magnetic lock for releasing the card holder on the 12 o&#39;clock position for transfer to the positioning device. 
     In one embodiment there is provided an engraving unit, wherein the card handler comprises a rotator with at least three positions, preferably with at least four positions (3-o&#39;clock, 6-o&#39;clock, 9-o&#39;clock and 12-o&#39;clock) to receive one card holder each. Preferably, the positions of the rotator have a lead-in face that align the card holder to the rotator when the cardholder is put back to the rotator. 
     In one embodiment there is provided an engraving unit, wherein the card handler comprises a camera which is adapted to take an image of a card holder once received in one of the positions of the rotator. Preferably, this information of the image is used to correct any off-set of the real position of the card to an ideal position of the card when engraving with the laser. Preferably, the image is taken before the position in which the card is engraved, for instance at the 9-o&#39;clock position instead of taking the picture in the cardholder under the laser (at 12-o&#39;clock). As a result, speed is increased since taking an image at 9-o&#39;clock can be done in parallel with the transfer and engraving at 12-o&#39;clock. Thus, the laser has not to wait for the image to be taken. 
     The object of the invention is also achieved by a method of operating a positioning device according to the invention, wherein the manipulator is moved according to the cardanic element and wherein the virtual pivot point of the cardanic element, the first axis of rotation and the second axis of rotation are placed on a predefined point in the space around the positioning device, preferably in the virtual card surface plane. 
     Further preferred is a method of operating a positioning device according to the invention, wherein the intersection of the first and the second axis of rotation is coincident with the virtual card center point. 
     Further, methods are preferred to transfer the cards from the transport unit to the card handler and to the positioning device and engraving the card and transferring back the card through all steps to the transport unit. Further details of the method are disclosed in the description in context of the products in this application above and in the detailed description of the figures. 
    
    
     
       The invention is described with respect to the figures. The figures show: 
         FIG. 1  a schematic view of an embodiment of a positioning device according to the present invention with two parallel linear guides and one perpendicular linear guide, 
         FIG. 2 a    a schematic top view of an embodiment of a positioning device according to the invention, 
         FIG. 2 b    a schematic side view of an embodiment according to  FIG. 2   a,    
         FIG. 3  a schematic side view of an embodiment of a positioning device with parallel linear guides, a treatment unit and a card handler according to the present invention, 
         FIG. 4  a schematic side view of an embodiment of a positioning device with non parallel linear guides, a treatment unit and a card handler according to the present invention. 
     
    
    
       FIG. 1  shows a schematic view of an embodiment of a positioning device according to the present invention with two parallel linear guides  26 . 2 ,  26 . 3  and one perpendicular linear guide  26 . 1 . A laser  100  with an axis L of the laser beam are directed on the center of a card holder  10  of a manipulator  20 . In the card holder  10  is a card  111  with a surface plane  11 . In the center of the card  111  is a virtual card center point  12 . Linear guides  26 . 2  and  26 . 3  are arranged parallel to each other in z-direction and connected to the manipulator  20  at contact points  24 . 2  and  24 . 3 , respectively. A third linear guide  26 . 1  is arrange perpendicular to the other linear guides  26 . 2  and  26 . 3 . The cardanic system  27  has two axis of movement A 1  and A 2 . The intersection of these axis A 1  and A 2  is the virtual pivot point  28  of the cardanic element or system  27 . By means of the manipulator, the card holder  10  and thus the card  111  can be moved around, especially in the beam of the laser  100 . These movements are rotational movements as well as linear movements, for instance towards the laser and away from the laser  100 . Further, a card handler  60  is shown with a rotator  65  and four different positions  66 . 3  (not shown),  66 . 6 ,  66 . 9  and  66 . 12  to hold a card holder  10 . 
       FIG. 2 a    shows a schematic drawing of an embodiment of a positioning device according to the invention. A positioning device  1  for rotatably positioning a card  111  with respect to a treatment unit (above the drawing plane) with an axis of treatment L is shown. A card holder  10  is holding a card  111  in a fixed position. Within the card holder  10  a virtual card surface plane  11  is shown which is coincident with the surface of the card  111  facing the treatment unit  100 , i.e. above the plane of drawing. 
     A virtual card center point  12  is coincident with the intersection point of the axis of treatment L and the virtual card surface plane  11 . The card holder  10  is attached to the manipulator  20  by the use of a gripper  15 . The manipulator  20  comprises 
     a cardanic element  27  with a first axis of rotation A 1  and a second axis of rotation A 2  and a virtual pivot point  28  being the intersection of the first and the second axis of rotation A 1  and A 2 . Further, three linear guides  26 . 1 ,  26 . 2 ,  26 . 3  can be seen in top view. Each linear guide  26 . 1 ,  26 . 2 ,  26 . 3  is flexibly attached to the cardanic element  27  at a contact point  24 . 1 ,  24 . 2 ,  24 . 3 . 
       FIG. 2 b    shows a schematic side view of an embodiment according to  FIG. 2 a   . In this view, the linear guides  26 . 1 ,  26 . 2  and  26 . 3  can be seen from the side and also the laser  100  and the axis of the laser beam L can be seen. The axis L coincides with the intersection of the axis of rotation A 1  and A 2  of the cardanic system  27 . The virtual card surface plane  11  coincides with the surface of the card  111  facing the laser  100 , i.e. the upper side of the card  111 . The virtual card center point  12  coincides with the intersection of the axis L and the surface of the card. 
     When moving the linear guides  26 . 1 ,  26 . 2 ,  26 . 3  the cardanic system  27  moves around the two axis of rotation A 1  and A 2  and thus creates a virtual pivot point  28  of the cardanic system  27  on the surface of the card  111  at the intersection of the laser beam L and the surface of the card. 
       FIG. 3  shows a schematic side view of an embodiment of a positioning device  1 , a laser as a treatment unit  100  and a card handler  60  according to the present invention. In the positioning device  1  the three linear guides  26 . 1 ,  26 . 2 ,  26 . 3  can be seen, whereas the columns  26 . 2  and  26 . 3  are pictured in flight. The cardanic element  27  is shown schematically without the guidings and the mechanical structure. The card holder  10  holds a card  111  whereas the surface of the card  111  coincides with the virtual card surface plane  11 . The first and second axis of rotation A 1  and A 2  of the cardanic system  27  are shown. A 2  is shown in dotted line whereas A 1  is perpendicular to the drawing plane. 
     The working beam along the axis L of the laser  100  is hitting the surface of the card  111  at the virtual card center point  12  which is also the virtual pivot point  28  of the cardanic system  27 . The card holder  10  is shown in a tilted angle around the axis A 1  but not tilted around the axis A 2 . The laser beam along axis L engraves an image on the card  111 . Further, a x-y shifting unit  30  is shown schematically with which the manipulator can be moved in x-y direction thus shifting the virtual pivot point of the system in the x-y plane. 
     In  FIG. 3 , also a card handler  60  is shown with a rotator  65  and four positions of the rotator  66 . 1 ,  66 . 2 ,  663 . and  66 . 4 . In these positions, card holders  10  are attached. A camera  68  is shown which is directed onto position  66 . 3 , i.e. the 9-o&#39;clock position of the rotator turning clockwise. 
     The camera takes an image of position  66 . 3  showing the card in the card holder in position  66 . 3  and any off-sets of the card from an ideal position of the card in the card holder. This information is used in the next step. When the rotator  65  rotates 90° clockwise, the card holder on position  66 . 3  moves to position  66 . 4 . The positioning device  10  takes the card holder and positions it in the laser beam L. A control unit  40  determines the off-set from the image taken on the 9-o&#39;clock position and compensates this off-set when controlling the cardanic element  27  by controlling the linear guides  26 . 1 ,  26 . 2 ,  26 . 3  thus moving the card holder in such a way that the laser engraves an image as planned and compensates for the off-set of the card in the card holder. The off-set can also be compensated by adjusting the laser beam when engraving or preferably a combination of both. 
       FIG. 4  shows a schematic side view of an embodiment of a positioning unit  20  with non parallel linear guides  26 . 1 ,  26 . 2  and  26 . 3 , a treatment unit  100  and a card handler  60  according to the present invention. The linear guides are not parallel and can manipulate the manipulator when attacking on the contact points. The cardanic system is only shown schematically and not shown in detail. The card holder  10  can be moved within the working area of the laser  100  and the axis of the beam L. The card handler  60  is shown and has the functions as described above. 
     REFERENCE SIGNS 
     
         
         A 1  first axis of rotation (of the cardanic element) 
         A 2  second axis of rotation (of the cardanic element) 
         L axis of treatment (of the treatment unit) 
           1  Positioning device 
           7  interface to a transport unit 
           8  transport unit 
           10  card holder 
           11  virtual card surface plane 
           12  virtual card center point 
           15  gripper 
           20  manipulator 
           23  spherical bearing element, especially a ball joint 
           24  contact point of the linear guide on the manipulator 
           26  linear guide 
           27  cardanic element 
           28  virtual pivot point of the cardanic element 
           30  x-y shifting unit 
           40  controller unit 
           60  card handler 
           65  rotator 
           66  position on the rotator for a card holder 
           68  camera 
           100  treatment unit, especially a laser 
           111  flat piece, especially a card