Abstract:
An extrusion and inspection apparatus is provided. Specifically, the apparatus includes a generally horizontal surface adapted to support a substrate and a coating die that extrudes fluid onto the substrate. A shuttle having a bridge with the coating die mounted thereon moves the coating die generally parallel to the substrate. In addition to lateral motion parallel to the substrate, the apparatus includes a gauging member that positions the die to at least one predetermined position above the substrate. A light source secured to the bridge is also employed to illuminate the substrate before and/or after coating. The apparatus also includes an imager secured to the bridge where the imager obtains images of the substrate during illumination.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Patent Application Ser. No. 60/911,017, filed on Apr. 10, 2007, and which is hereby incorporated by reference for all purposes. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates generally to methods and apparatus for depositing material onto a substrate. 
       BACKGROUND OF THE INVENTION 
       [0003]    In many applications today, extruders are employed to provide films onto substrates. Some of these applications include the production of Flat Panel Displays (FPD) and semiconductors. Additionally, for the purposes of quality assurance (among other purposes), inspection of the film on the substrate is employed. Conventionally, separate machines are employed to perform the functions of extruding a film and inspecting the film. Some examples of such conventional apparatuses are U.S. Pat. Nos. 5,853,812; 4,938,994; and 6,309,692. Therefore, there is a need for a method and apparatus that can perform both the functions of extrusion and inspection. 
       SUMMARY 
       [0004]    The present invention, accordingly, provides an extrusion and inspection apparatus in accordance with a preferred embodiment of the present invention. Specifically, the apparatus includes a generally horizontal surface adapted to support a substrate and a coating die that extrudes fluid onto the substrate. A shuttle having a bridge with the coating die mounted thereon moves the coating die generally parallel to the substrate. In addition to lateral motion parallel to the substrate, the apparatus includes a gauging member that positions the die to at least one predetermined position above the substrate. A light source secured to the bridge is also employed to illuminate the substrate before and/or after coating. The apparatus also includes an imager secured to the bridge where the imager obtains images of the substrate during illumination. 
         [0005]    In accordance with a preferred embodiment of the present invention, a method of extruding and inspecting is also provided. A substrate is illuminated prior to coating. Images of the substrate are obtained during illumination prior to coating. A bridge is adjusted to a predetermined height above the substrate. The bridge is moved in a plane that is generally parallel to the substrate. A liquid is extruded onto the substrate. The substrate and extrudate are illuminated. Images of the substrate and extrudate are obtained, and the substrate and extrudate are evaluated to determine the positions of errors. 
         [0006]    Additionally, in accordance with a preferred embodiment of the present invention, a system for coating a substrate with a material is provided. The system includes a movable shuttle, a dispenser carried by the shuttle, a chuck for holding the substrate, and an imaging apparatus carried by the shuttle and arranged to obtain image characteristics of the substrate before and/or after coating. The dispenser dispenses the material onto the substrate, and the substrate remains in a fixed position relative to the shuttle. 
         [0007]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
           [0009]      FIG. 1  is an isometric view of an extrusion and inspection apparatus in accordance with a preferred embodiment of the present invention; and 
           [0010]      FIG. 2  is an isometric view of the inspection camera system in accordance with a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Referring to  FIG. 1  of the drawings, the reference numeral  100  generally depicts the coating apparatus  100  according to a preferred embodiment of the present invention. A base  102  with a rail system  104  mounted thereon forms a foundation along which the shuttle or transport system  106  travels for cleaning and priming of the dispensing head or die  118 , and coating operations of the substrate  108 . Specifically, the dispensing head or die  118  and a gauging member (not shown) are mounted to the bridge  110 , which extends generally perpendicular between the rails of the rail system  104 . 
         [0012]    Also, a chuck  114  is secured to the base  102  through chuck holders  116 . Chuck  114  provides support and positioning of substrate  108 . Preferably, the chuck  114  employs a vacuum to secure or “hold down” the substrate  108  in a generally fixed horizontal position relative to the shuttle  106  during operation of the coating apparatus  100 . In a preferred embodiment of this invention, chuck holder  116  comprises a structure which will preferably support the chuck  114  principally at a plurality of points around the periphery of the chuck  114 . Correspondingly, the chuck  114  is ground so that it is as flat as possible as supported. Alternatively, the chuck  114  can be formed so as to selectively deform to compensate for deformation in the shuttle  106  and head  118 . 
         [0013]    In particular, a gauging member (not shown) can be implemented on the shuttle  106  to fine tune the gap between the dispenser or dispensing head  118  and the substrate  108  in real time during the coating operation. A height sensor as part of the gauging member (not shown) is appropriately zeroed while the head  118  is at the correct height, and a correction signal is subsequently generated whenever the height deviates above or below the preset level. The height sensor typically comprises one or more non-contact laser sensors that measure the relative height above the substrate  108 , which constitutes an indirect feedback control. Alternatively, a physically contacting probe or rod can be used to supply direct feedback control 
         [0014]    These feedback controls are used by a control system to adjust the height of the dispensing head  118  and the bridge  110 . The control system for the gauging member is generally comprised of computer hardware and software that convert the feedback signal into information suitable to drive the position motor(s) to restore the dispensing head to the proper height. This process of height self-correction typically begins at the start of the coating process and continues throughout the coating process. However, it is preferable to make this adjustment only at the start of the coating process (to compensate for various thicknesses of different substrates), and to not make adjustments during the coating. 
         [0015]    In operation, the dispensing head  118  moves above the chuck  114  supporting substrate  108 . During motion of the dispensing head  118 , its height can be adjusted by the gauging member (not shown). The dispensing head  118  is preferably a linear extrusion head attached to fluid manifold preferably containing a bead forming orifice substantially as described in U.S. Pat. No. 4,696,885, titled “METHOD OF FORMING A LARGE SURFACE AREA INTEGRATED CIRCUIT.” Although a stationary substrate  108  and movable shuttle  106  is preferred because it occupies less space, the head  118  and camera systems  200  could be maintained stationary while the substrate  108  is moved relative thereto. 
         [0016]    The travel of the shuttle  106  preferably will be at least long enough to permit the dispensing head  118  to coat the largest substrate to be placed on the apparatus  100  and to clear the substrate  108  by a sufficient distance to permit the substrate  108  to be removed by external personnel or machinery. Although, this range may be reduced by providing for some movement of the substrate  108  during coating. The travel of the shuttle  106  will preferably also be long enough so that in addition to clearing the substrate  108 , the shuttle  106  will be able to gain access to utility station  112 . 
         [0017]    To reduce the system footprint, and to improve coating performance, particularly on the leading edge of a substrate  108  (starting point for the coating operation), substrate  108  is located as close as possible to utility station  112 . Preferably, the shuttle  106  carries the bridge  110  and the dispensing head  118  to the utility station  112  for head cleaning and for priming of the bead either before or during the loading of the substrate  108 . The shuttle  106  then carries the bridge  110  and the dispensing head  118  to the near edge of the substrate  108  (the side closest to the station  112 ) so that coating of the substrate  108  may begin. The shuttle  106  then carries the dispensing head  118  across the substrate at a carefully monitored and predetermined rate, preferably under computer control, while the dispensing head  118  dispenses coating material at a controlled rate onto the substrate  108 . Once the shuttle  106  has traveled to a point where the dispensing head  118  has coated the entire substrate  108  or that portion to be coated, fluid flow to the dispensing head  118  is discontinued. 
         [0018]    It should also be appreciated that there is no limitation that the present invention coat the entire surface of the substrate  108 . For example, the motion of the head  118  may be stopped at some point prior to fully coating a substrate  108  where only a portion of the substrate  108  is desired to be coated. Additionally, or alternatively, the length of the head  118  may be such that only a portion of the substrate  108  is coated even with full travel of the head  118 . 
         [0019]    In addition to extruding a liquid onto the substrate  108 , the apparatus  100  also inspects the substrate  108 . During the manufacture of Thin Film Transistor (TFT) screens, Liquid Crystal Displays (LCDs), and other such devices, it is important to identify processing defects. To accomplish this, a number of camera systems  200  are employed. Each of these systems  200  are secured to or mounted on the bridge  110 , so that, upon completion of the extrusion process(es), inspection of the substrate  108  can commence. By incorporating the camera systems  200  into the apparatus  100 , the number of machines used to process or otherwise manufacture the finished product, such as an LCD, is reduced. This reduction in the total number of machines necessary to produce such products results in a reduction in the overall footprint of the equipment, and in a reduction of the total investment for the manufacturing line. 
         [0020]    Now turning to  FIG. 2  of the drawings, the camera systems  200  can be seen in greater detail. Each of the camera systems  200 , which are secured or mounted to the bridge  100  include a light source  202 . Typically, this light source is a solid state light source, such as a Light Emitting Diode (LED) or diode laser. The light source  202  illuminates the substrate  108  and the extrudate located on the substrate  108 . Operating in conjunction with the light source  202  are a number of imagers or cameras  204 , which are preferably high resolution Charged Coupled Devices (CCDs), that detect radiation reflected off of the substrate  108  and/or the extrudate. Incorporated with these cameras  204  are optical elements, such as diffraction limited optical elements, to produce clearer images and reduce optical errors. Typically, these systems  200  are adapted to detect particles on the extrudate or surface of about 10 μm in size. 
         [0021]    Now turning back to  FIG. 1 , in operation, prior to and upon completion of the extrusion process(es), the bridge  110  passes back over the substrate  108  and the extrudate located on the substrate  108 . Light source(s)  202  of the respective systems  200  illuminate the substrate  108  and/or extrudate. Light or radiation reflected off of the substrate  108  and/or extrudate is captured by the respective cameras  204  and are relayed to a data capture system (not shown) which interprets the results and reports errors in the extrusion processing or in the substrate  108 . Additionally, the systems  200  can also be employed to examine substrate  108  without any particular coating process. 
         [0022]    Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.