Abstract:
A system for coating items using a self-contained vacuum fixture. The system providing lower cost, complexity, and form factor in a coating machine. A self-contained, self-generating vacuum feature avoids the need for an external vacuum supply. The system providing fewer errors and downtime.

Description:
RELATED APPLICATIONS  
       [0001]    This patent application claims the benefit under 35 U.S.C. 119 of U.S. Provisional Patent Applications Nos. 60/337,223, filed Dec. 3, 2001, and 60/337,251, filed Dec. 3, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to systems for coating items, and more particularly to a system for spin coating items using a self-contained vacuum fixture.  
         BACKGROUND  
         [0003]    Coating vacuum systems include a holding device for holding the item to be coated. For example, machines that coat opthalmic lenses use an external vacuum supply which provides vacuum to some of the actuators in the system and provides a vacuum to the holding device. Such machines spin the lens while a chemical process is used to coat the lens.  
           [0004]    [0004]FIG. 1 is a diagram showing a prior art spin coating system  8  using a holding device  4  requiring an external vacuum source  6  to hold part  5 . The prior art spin coating system  8  communicates the vacuum using vacuum input line  7  connected to the external vacuum source  6 . The vacuum reaches holding device  4  via vacuum supply line  2  and rotary union  3 .  
           [0005]    System  8  has several problems. For example, the spinning aspect creates complications in providing vacuum to the holding device  4 . In such systems the holding device  4  must receive vacuum during the spinning, or the part  5  to be coated (i.e., lens) will fall.  
           [0006]    Another problem is that the external vacuum source  6  and connected vacuum components are prone to failure. Such failures increase downtime and the cost of maintenance.  
           [0007]    Another problem is that one type of existing vacuum generating source utilizes an external air supply plumbed to an air driven vacuum generator. This vacuum generation can be problematic due to contaminations and/or insufficient air supply. Air driven vacuum generators also require and use large volumes of air.  
           [0008]    Another example of vacuum generation is a central stand-alone electric vacuum pump. This component, too, is prone to failure.  
           [0009]    Yet another problem is that external vacuum sources add to the cost of a coating system and the amount of space required to operate the machine.  
           [0010]    Thus, there is a need in the art for an improved system for coating items providing reduced downtime, maintenance and cost.  
         SUMMARY  
         [0011]    The present invention relates to a system for coating items using a self-contained vacuum fixture. The present system solves the problems in the art stated above and other problems not expressly stated herein.  
           [0012]    In one embodiment, the system uses a vacuum fixture having a self-contained vacuum feature so that an external vacuum system is not required. The system also does not require the vacuum line and components needed to supply vacuum to the fixture.  
           [0013]    In one application, the present system is employed in spin coating machines. It is understood that other applications are possible, and one of skill in the art will appreciate other uses upon reading and understanding the present specification.  
           [0014]    This summary is intended to provide an overview of the subject matter of the present patent application. It is not intended to provide an exhaustive or exclusive explanation of the invention. The detailed description is included to provide further information. And the claims appended to the application and their equivalents provide the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0015]    [0015]FIG. 1 is a diagram showing a prior art system using a holding device requiring an external vacuum system.  
         [0016]    [0016]FIG. 2 is a diagram showing a coating system including one embodiment of the self-contained vacuum fixture with self-generated vacuum according to one embodiment of the present system.  
         [0017]    [0017]FIG. 3 is a top view diagram of a multiple station system showing wash, coat, and cure positions according to one embodiment of the present system.  
         [0018]    [0018]FIG. 4 is a side view of the system of FIG. 3 according to one embodiment of the present system.  
         [0019]    [0019]FIG. 5 is a diagram of one example of a self-contained vacuum fixture according to one embodiment of the present system.  
         [0020]    [0020]FIG. 6 is a diagram of the self-contained vacuum fixture of FIG. 5 in a vacuum released state according to one embodiment of the present system.  
         [0021]    [0021]FIG. 7 is a diagram of the self-contained vacuum fixture of FIG. 5 in a vacuum held state according to one embodiment of the present system.  
         [0022]    [0022]FIG. 8 is a side view showing one example of attachment of the vacuum fixture according to one embodiment of the present system.  
         [0023]    [0023]FIG. 9 is a side view showing one example of attachment of the vacuum fixture according to one embodiment of the present system.  
         [0024]    [0024]FIG. 10 shows one example of a pick and place application employing the vacuum fixture according to one embodiment of the present system.  
         [0025]    [0025]FIG. 11 shows one example of a pick and place application employing the vacuum fixture according to one embodiment of the present system.  
     
    
     DETAILED DESCRIPTION  
       [0026]    This detailed description is intended to provide details on how to make and use the present invention, including a best mode of the invention. The embodiments provided herein may differ in electrical, mechanical, and chemical nature without departing from the scope of the present invention. It is understood that some organizational variation in the embodiments of apparatus and method provided herein may fall within the scope of the present invention, which is provided by the appended claims and equivalents thereto.  
         [0027]    The present system and teachings provide advantages over the previous methods and apparatus, including, but not limited to, solving the problems stated in the art in the Background.  
         [0028]    [0028]FIG. 2 is a diagram showing a coating system  200  including one embodiment of the self-contained vacuum fixture  222  with self-generated vacuum according to one embodiment of the present system. Fixture  222  holds a part  210  for coating by a chemical spray from nozzle  260 . Motor  205  can turn the fixture  222  to evenly spin coat the part  210  within coating chamber  220 . The chemical residing in coating reservoir  230  is pressurized by pump motor  250  and sent from pump head  270  through filter  240  to nozzle  260 . The coating reservoir  230  and pump motor  250  form an assembly  280  which is attached to the coating chamber  220 . In one embodiment the attachment uses a ¼ turn cw attachment point to a nylon coating chamber bottom. Such a system uses a ¼ ccw turn removal. In one embodiment the resevoir  230  is nylon material.  
         [0029]    In one embodiment, the pump head  270  is built into the bottom of the reservoir and is magnetically coupled to the pump motor making a seal-less fit between pump head and pump motor.  
         [0030]    The coating reservoir and pump are removable without loss of coating fluid, as there are no external fluid tubes leading to a pump or filter. This provides a quick change feature which is desireable in coating machines. This also avoids loss of fluids due to external tubes running to the pump or filter, making all fluids in the reservoir ready for coating delivery. The pump also stays primed. A shorter time is needed to apply chemicals. Chemical overspray is reduced.  
         [0031]    In one embodiment, the lens head is lowered onto a coating fountain and the coating fans out over the lens. The lens is rotating at approximately 200 RPM to allow coating to flow over the full surface of the lens. Coating applied in this manner avoids the need for aeration of coating fluid imparted on the lens. This also leaves the lens free of pits.  
         [0032]    In one embodiment of the system in FIG. 2, the self-contained vacuum fixture  222  is the embodiment shown in FIG. 5 and discussed below. In one embodiment, the self-contained vacuum fixture  222  is a suction cup. In one embodiment, the attachment mount is the example of FIG. 8, discussed below. In one embodiment, the attachment mount is the example of FIG. 9, discussed below.  
         [0033]    [0033]FIG. 3 is a top view diagram showing a multiple feature system including wash  300 , coat  310 , and cure  320  positions according to one embodiment of the present system. Arm  330  pivots to place the self-contained vacuum fixture (not shown) at the different positions. Motor  340  spins the self-contained vacuum fixture.  
         [0034]    [0034]FIG. 4 is a side view of the system of FIG. 3 according to one embodiment of the present system. Arm  330  holds self-contained vacuum fixture  422  in position. Arm  330  also moves the vacuum fixture  422  up or down as required. Motor  340  spins fixture  422  and part  400 .  
         [0035]    [0035]FIG. 5 is a diagram of one example of a self-contained vacuum fixture  500  according to one embodiment of the present system. In this example, fixture  500  includes a cup  505  attached to a spool  510 . A ball detent  515  holds spool  510  in position as the cup/spool assembly is depressed. An o-ring  520  applies pressure to ball detent  515 . When an object is pressed onto the vacuum cup  505 , air is pressurized within the spool  510  and the pressurized air moves the seal plunger  560  off of seal allowing air to escape. Once air escapes the plunger  560  seats on a seal creating a vacuum on the object so that the object remains on the cup  505 . The seal plunger  560  mates with spool seal  530  to maintain the vacuum and is kept in position in part with the force exerted by spring  540 . FIG. 7 is a diagram of the self-contained vacuum fixture of FIG. 5 in a vacuum held state according to one embodiment of the present system.  
         [0036]    To remove the object, it is pulled away from the cup to break its seal and dissipate the vacuum. This occurs because pulling on the object also pulls vacuum cup  505 , which draws spool  510  out of body  580 . As the spool  510  is drawn out of the body, the ball detent  515  will leave its groove and the seal plunger  560  is stopped by plunger retaining pin  535 . After the seal plunger  560  is stopped, the vacuum is broken as the seal plunger  560  is pulled out of the spool seal  530 . The object can be removed from vacuum cup  505  since the vacuum has been lost. Spool  510  cannot leave body  580  since it stops when it reaches spool retaining pin  525 . The released state of the self-contained vacuum fixture of FIG. 5 is shown in FIG. 6, according to one embodiment of the present system.  
         [0037]    This design provides an affirmative hold of the object in the held state. The design also provides a way to remove the object without excessive force on the object and the overall assembly.  
         [0038]    In one embodiment the materials are non-ferrous. In one embodiment the materials are ferrous. In varying embodiments, differently shaped vacuum cups  505  are employed. The type of vacuum cups used are determined by the size and shape of object to be held. In one embodiment, an automatic release is used whereby the object is released with an electrical valve operation. It is understood that the vacuum fixture  500  is used in rotating embodiments. In alternate embodiments, the vacuum fixture  500  is used in non-rotating embodiments. It is understood that the vacuum fixture  500  may be used in different spatial positions and orientations.  
         [0039]    One skilled in the art, upon reading and understanding this demonstrative embodiment, will understand that variations in the design of the self-contained vacuum fixture may occur without departing from the scope of the present invention.  
         [0040]    [0040]FIG. 8 is a side view showing one example of attachment of the vacuum fixture according to one embodiment of the present system. The self-contained vacuum fixture  822  is attached to the motor shaft  810  of motor  800  using set screws. In the embodiment shown three set screws  820  are used; however, it is understood that other numbers of screws may be used. In alternate embodiments, other fasteners may be used without departing from the scope of the present system.  
         [0041]    [0041]FIG. 9 is a side view showing one example of attachment of the vacuum fixture according to one embodiment of the present system. A quick change adapter  900  is used to provide a quick change between fixtures  822 . In the embodiment shown, the quick change adapter  900  is attached to motor shaft  910  using set screws  820 . Vacuum fixture  822  includes a channel  930  which mates with lock pin  920  when inserted into the quick change adapter  900 . Spring  910  provides tension on the stem of vacuum fixture  822  to maintain lock pin  920  in fixed engagement with the channel  930 . The vacuum fixture  822  is removed by an upward force and turning of the fixture.  
         [0042]    Upon reading and understanding the specification one skilled in the art will appreciate that other quick locking mechanisms may be used.  
         [0043]    [0043]FIG. 10 and FIG. 11 show examples of a pick and place application employing the vacuum fixture according to one embodiment of the present system. In one embodiment, applications for pick and place incorporate and control electrically activated detents. In one embodiment the pick and place system controls mechanical detents. Such embodiments may be useful for applications where the heavier objects are handled.  
         [0044]    It is also contemplated that a number of vacuum fixtures may be automatically changed using a quick change adapter and the pick and place system programmed to engage and disengage fixtures. This allows the system to use a plurality of vacuum fixtures. In one embodiment the system uses a different fixture for a differently-shaped object. In another embodiment, the system uses different fixtures having different holding forces for differently weighted objects. It is also contemplated that the system may select different fixtures for different portions of a process. Such as a chemical resistant vacuum fixture for a coating process and a heat resistant fixture for a curing process. Other variations are possible without departing from the scope and spirit of the present system.  
         [0045]    Lens Coating Applications  
         [0046]    In embodiments where lens coating is performed a number of chemicals and chemical processes may be employed, including coating, curing, spin coating, dip coating, cleaning. One such application is the application of scratch resistant and scratch proof coatings on optical lens blanks. The processes include the chemicals needed for each operation. It is understood that known chemical processes and chemicals may be used, including  
         [0047]    MFR Chemical Numbers  
         [0048]    Ultra Optics #UV-NVC COATING SOLUTION  
         [0049]    Ultra Optics #PFD 1600 THERMAL  
         [0050]    Ultra Optics #UV-NV COATING SOLUTION  
         [0051]    Ultra Optics #UVX  
         [0052]    Ultra Optics #UV 33  
         [0053]    LTI/Colburn #SHC 3100  
         [0054]    LTI/Colburn #HT 2000  
         [0055]    LTI/Colburn #HT 825  
         [0056]    LTI/Colburn #HT 150  
         [0057]    SDC- #SILVUE 339  
         [0058]    Those skilled in the art will understand that other processes may be performed and that other chemicals may be used with the system provided herein.