Abstract:
Various methods and apparatus for simultaneously texturing two single-sided hard memory disks is provided. The two disks are placed in a concentric contact merge orientation such that the outwardly facing surface of each disk may be simultaneously subjected to texturing by equipment designed to texture one double-sided disk.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Priority is claimed from U.S. Provisional Patent Application Ser. Nos. 60/417,623 and 60/417,711, both filed Oct. 10, 2002, which are incorporated by reference herein in their entirety. 
    
    
     The subject matter of the present application is related to the following applications, each of which has a filing date of May 9, 2003: U.S. patent application Ser. No. 10/434,550 entitled “Single-Sided Sputtered Magnetic Recording Disks” in the name of Clasara et al. (Publication No. US-2003-0211361-A1); U.S. patent application Ser. No. 10/435,361 entitled “Dual Disk Transport Mechanism Processing Two Disks Tilted Toward Each Other” in the name of Grow et al. (Publication No. US-2003-0208899-A1); U.S. patent application Ser. No. 10/435,358 entitled “Information-Storage Media With Dissimilar Outer Diameter and/or Inner Diameter Chamfer Designs On Two Sides” in the name of Clasara et al. (Publication No. US-2003-0210498-A1); U.S. patent application Ser. No. 10/435,360 entitled “Method of Merging Two Disks Concentrically Without Gap Between Disks” in the name of Buitron (Publication No. US-2004-0016214-A1); U.S. patent application Ser. No. 10/434,551 entitled “Apparatus for Combining or Separating Disk Pairs Simultaneously” in the name of Buitron et al. (Publication No. US-2004-0035757-A1); U.S. patent application Ser. No. 10/435,572 entitled “Method of Simultaneous Two-Disk Processing of Single-Sided Magnetic Recording Disks” in the name of Buitron et al. (Publication No. US-2003-0211275-A1); U.S. patent application Ser. No. 10/435,161 entitled “W-Patterned Tools for Transporting/Handling Pairs of Disks” in the name of Buitron et al. (Publication No. US-2003-0209421-A1); U.S. patent application Ser. No. 10/435,295 entitled “Method for Servo Pattern Application on Single-Side Processed Disks in a Merged State” in the name of Valeri (Publication No. US-2004-0013011-A1); U.S. patent application Ser. No. 10/535,227 entitled “Cassette for Holding Disks of Multiple Form Factors” in the name of Buitron et al. (Publication No. US-2004-0069662-A1); U.S. patent application Ser. No. 10/434,546 entitled “Automated Merge Nest for Pairs of Magnetic Storage Disks” in the name of Crofton et al. (Publication No. US-2004-00721535-A1); U.S. patent application Ser. No. 10/435,293 entitled “Apparatus for Simultaneous Two-Disk Scrubbing and Washing” in the name of Crofton et al. (Publication No. US-2004-0070859-A1); U.S. patent application Ser. No. 10/435,362 entitled “Cassette Apparatus for Holding 25 Pairs of Disks for Manufacturing Process” in the name of Buitron et al. (Publication No. US-2004-0068862-A1); and U.S. patent application Ser. No. 10/434,540 entitled “Method of Lubricating Multiple Magnetic Storage Disks in Close Proximity” in the name of Buitron et al. (Publication No. US-2003-0209389-A1). Each of these applications is incorporated by reference in its entirety as if stated herein. 
     FIELD OF THE INVENTION 
     The present invention is directed to various apparatus and associated methods for simultaneously processing two hard memory disks. More specifically, the present invention relates to simultaneous single-sided texturing of pairs of disks. 
     BACKGROUND OF THE INVENTION 
     Hard disk drives are an efficient and cost effective solution for data storage. Depending upon the requirements of the particular application, a disk drive may include anywhere from one to eight hard disks and data may be stored on one or both surfaces of each disk. While hard disk drives are traditionally thought of as a component of a personal computer or as a network server, usage has expanded to include other storage applications such as set top boxes for recording and time shifting of television programs, personal digital assistants, cameras, music players and other consumer electronic devices, each having differing information storage capacity requirements. 
     Typically, hard memory disks are produced with functional magnetic recording capabilities on both sides or surfaces of the disk. In conventional practice, these hard disks are produced by subjecting both sides of a raw material substrate disk, such as glass, aluminum or some other suitable material, to numerous manufacturing processes. Active materials are deposited on both sides of the substrate disk and both sides of the disk are subject to full processing such that both sides of the disk may be referred to as active or functional from a memory storage stand point. The end result is that both sides of the finished disk have the necessary materials and characteristics required to effect magnetic recording and provide data storage. These are generally referred to as double-sided process disks. Assuming both surfaces pass certification testing and have no defects, both sides of the disk may be referred to as active or functional for memory storage purposes. These disks are referred as double-sided test pass disks. Double-sided test pass disks may be used in a disk drive for double-sided recording. 
     Conventional double-sided processing of hard memory disks involves a number of discrete steps. Typically, twenty-five substrate disks are placed in a plastic cassette, axially aligned in a single row. Because the disk manufacturing processes are conducted at different locations using different equipment, the cassettes are moved from work station to work station. For most processes, the substrate disks are individually removed from the cassette by automated equipment, both sides or surfaces of each disk are subjected to the particular process, and the processed disk is returned to the cassette. Once each disk has been fully processed and returned to the cassette, the cassette is transferred to the next work station for further processing of the disks. 
     More particularly, in a conventional double-sided disk manufacturing process, the substrate disks are initially subjected to data zone texturing. Texturing prepares the surfaces of the substrate disks to receive layers of materials which will provide the active or memory storage capabilities on each disk surface. Texturing may typically be accomplished in two ways: fixed abrasive texturing or free abrasive texturing. Fixed abrasive texturing is analogous to sanding, in which a fine grade sand paper or fabric is pressed against both sides of a spinning substrate disk to roughen or texturize both surfaces. Free abrasive texturing involves applying a rough woven fabric against the disk surfaces in the presence of a slurry. The slurry typically contains diamond particles, which perform the texturing, a coolant to reduce heat generated in the texturing process and deionized water as the base solution. Texturing is typically followed by washing to remove particulate generated during texturing. Washing is a multi-stage process and usually includes scrubbing of the disk surfaces. The textured substrate disks are then subjected to a drying process. Drying is performed on an entire cassette of disk drives at a time. Following drying, the textured substrate disks are subjected to laser zone texturing. Laser zone texturing does not involve physically contacting and applying pressure against the substrate disk surfaces like data zone texturing. Rather, a laser beam is focused on and interacts with discrete portions of the disk surface, primarily to create an array of bumps for the head and slider assembly to land on and take off from. Laser zone texturing is performed one disk at a time. The disks are then washed again. Following a drying step, the disks are individually subjected to a process which adds layers of material to both surfaces for purposes of creating data storage capabilities. This can be accomplished by sputtering, deposition or by other techniques known to persons of skill in the art. Following the addition of layers of material to each surface, a lubricant layer typically is applied. The lubrication process can be accomplished by subjecting an entire cassette of disks to a liquid lubricant; it does not need to be done one disk at a time. Following lubrication, the disks are individually subjected to surface burnishing to remove asperities, enhance bonding of the lubricant to the disk surface and otherwise provide a generally uniform finish to the disk surface. Following burnishing, the disks are subjected to various types of testing. Examples of testing include glide testing to find and remove disks with asperities that could affect flying at the head/slider assembly and certification testing which is writing to and reading from the disk surfaces. Certification testing is also used to locate and remove disks with defects that make the surface unuseable for data storage. The finished disks can then be subjected to a servo-writing process and placed in disk drives, or placed in disk drives then subjected to servo-writing. The data zone texturing, laser zone texturing, scrubbing, sputtering, burnishing and testing processes are done one disk at a time, with each surface of a single disk being processed simultaneously. 
     Although the active materials and manufacturing processes, by their nature, are difficult and expensive to employ, over the years, the technology used to manufacture hard memory disks has rapidly progressed. As a result, the density of information that can be stored on a disk surface is remarkable. Indeed, double-sided test pass disks used in personal computers have much greater storage capacity than most consumers require during the useful life of the computer. Consumers thus are forced to pay substantial amounts for excess storage capacity and the components to access the excess storage capacity. This has caused some disk drive manufacturers, in some current applications, to manufacture and sell disk drives which utilize only one side of a double-sided test pass disk for storage purposes or which use the good side of a double-sided process disk where one surface passed certification testing and the second surface failed. In either case, the second surface, despite being fully processed, is unused. However, the disk drive manufacturer reduces its cost by eliminating the mechanical and electrical components needed to access the unused disk surface. These disk drives are referred to as single-side drives and are typically used in low-end or economy disk drives to appeal to the low cost end of the marketplace. Although this approach may reduce some cost, it does not reduce the wasted cost of manufacturing the unused storage surface of each disk. Thus, substantial savings can be achieved by not only manufacturing disks with a single active or functional side, but doing so in a cost-effective manner. 
     In contrast to a double-sided disk, a single-sided disk has only one functional memory surface with active recording materials. It is not a double-sided process disk where one side is not accessed or where one side has failed testing. Rather, manufacturing processes are applied in a controlled manner only to one side of the disk using unique single-sided processing techniques. In contrast to conventional double-sided disks, active recording materials are only applied to, and full processing is only conducted on, one side of the disk. Thus, substantial savings are achieved by eliminating processing the second side of each disk. 
     Additionally, the present invention achieves advantages by utilizing conventional double-sided disk manufacturing equipment and processes, with limited modification. The present invention enables simultaneous processing of two substrate disks through the same equipment and processes used to manufacture double-sided disks. Simultaneously processing two substrate disks results in the production of two single-sided disks in the same time and using essentially the same equipment as currently is used in the production of one double-sided disk. However, each single-sided disk has only a single active or functional surface. For illustrative purposes  FIG. 1  shows a side-by-side schematic representation of the processing of one double-sided disk D d , depicted on the left side of  FIG. 1 , versus the simultaneous processing of two single-sided disks D s , depicted on the right side of  FIG. 1 . In each case, the double-sided disk or the two single-sided disks are subjected to the same process steps  1  through N, but the single-sided disk processing produces two disks in the same time the double-sided disk processing produces one disk. 
     A benefit provided by simultaneous single-sided processing of disks is a substantial cost savings achieved by eliminating the application of materials to and processing of one side of each disk. A further, and potentially significant cost savings can be achieved by utilizing existing double-sided disk processing equipment, with limited modification, to process pairs of single-sided disks. A still further benefit is a substantial increase in production (or reduction in processing time depending upon perspective). By utilizing existing double-sided disk processing equipment, approximately twice the productivity of a conventional double-sided production process is achieved (on the basis of numbers of disks produced) in the production of single-sided disks. Moreover, these increased productivity levels are achieved at approximately the same material cost, excepting the substrate disk, as producing half as many double-sided disks. 
     The simultaneous processing is achieved by combining two substrate disks together into a substrate disk pair or disk pair. A disk pair is two substrate disks that are oriented in a back-to-back relationship with the back-to-back surfaces either in direct physical contact or closely adjacent with a slight separation. The separation can be achieved with or without an intervening spacer. The substrate disk pair progresses through each process step in much the same way as one double-sided disk, but with only the outwardly facing surface of each disk in the pair being subjected to the full process. Thus, the outwardly facing surface of each pair becomes the active or functional surface and the inwardly facing surface of each pair remain inactive or non-functional. 
     For convenience and understanding, the following terms will have the definitions set forth:
         a) “R-side” and “L-side” refer to the active side and inactive side of a disk, respectively. R-side is the side that does or will have active recording materials and memory capability. The R-side may also be referred to as the active or functional side. The L-side is the side that has little or no active recording materials or memory capabilities; it is non-functional or inactive from a data storage stand point.   b) “Merge” means to bring two disks closer together to form a pair of disks, a disk pair or a substrate pair.   c) “Demerge,” conversely, means that a merged pair of disks is separated from each other.   d) “Disk” means a finished memory disk and all predecessor configurations during the manufacturing process starting with a substrate disk and progressing to a finished memory disk, depending upon the context of the sentence in which it is used.   e) “Disk pair” or “substrate pair” means two disks positioned in contact merge, gap merge or spacer merge orientation.   f) “Double-sided disk” means a single disk which has been subjected to double-sided processing, whether or not both sides of the disk have passed testing or only one side has passed testing.   g) “Gap merge” means a pair of disks that have been merged, but a space is maintained between the two merged disks. One or more spacers may or may not be used to maintain the gap or space. Gap merge includes both concentric and non-concentric merge. It should be understood that there is no precise dimension or limit to the space between the disks that causes them to be gap merged. Gap merge also includes the situation where the gap between the disks gradually decreases from one perimeter edge to the opposite perimeter edge of the disks when the two disks are angled toward each other. An example is when the bottom perimeter edges of the disks are spaced apart and the upper perimeter edges are in contact.   h) “Single-sided disks” means a single disk which has been subjected to single-side processing, where only one surface of the disk is fully processed.   i) “Spacer merge” means a spacer body is used to create spacing between two gap-merged disks.   j) “Contact merge” means a merged pair of disks where the inside surface of each disk is in contact with the inside surface of the other disk. Contact merge includes concentric and non-concentric merge.   k) “Concentric merge” means that two merged disks have the same axis and, assuming the two disks have the same outside diameter and inside diameter (as defined by the center aperture), their outer and inner perimeter edges are aligned.   l) “Concentric contact merge” means a pair of disks that are oriented in both a contact merge and a concentric merge.   m) “Non-concentric merge” or “off-centered merge” means the two merged disks are not concentric to each other or their perimeter edges are not aligned.   n) “Non-concentric contact merge” means the two contact merged disks are not concentric to each other or their perimeter edges are not aligned.       

     Referring to  FIG. 2 , a cross-section of a pair of gap-merged disks is shown. The R-side (active or functional side) is the outwardly facing surface R of each disk within the pair. The L-side (inactive or nonfunctional side) is the inwardly facing surface L of each disk within the pair. In comparison, a cross-section of a pair of concentric contact merged disks is shown in  FIG. 3 . The relative orientation of the R-side and L-side of each disk remains the same, however, the L-side of each disk of the pair are in contact and the outer and inner perimeter P of each disk is aligned with the outer and inner perimeter P of the other disk. 
     A conventional double-sided disk is shown in  FIG. 4 . The left side surface is referred to as the “A” side and the right side surface is referred to as the “B” side. Both the A and B sides are subjected to processing, including the addition of active or magnetic materials. In contrast, with reference to  FIGS. 2 and 3 , the R-side of each disk in a pair of disks is oriented on the outside of the pair and is subjected to processing in the same fashion as the A and B sides of a double-sided disk. Conversely, the L-side of each disk in a pair of disks is oriented on the inside of the pair and is not subjected to full processing in the same fashion as the A and B sides of a double-sided disk. 
     SUMMARY OF THE INVENTION 
     These and other benefits are addressed by the various embodiments and configurations of the present invention. For example, a benefit provided by the present invention is an increased output in the production of finished disks achieved by texturing two single-sided disks simultaneously. Another benefit is that, with limited modifications, the present invention can process pairs of single-sided disks utilizing existing processing equipment originally designed and built to texture double-sided disks. This results in substantial capital equipment savings which would otherwise be spent unnecessarily modifying existing equipment or creating new equipment to process single-sided disks. Moreover, as should be appreciated from a review of the specification and referenced drawings, the present invention has applicability in data zone texturing processes and laser zone texturing processes. 
     The present invention is generally directed to methods and apparatus for texturing the surface of two single-sided disks simultaneously. In one embodiment, a pair of gap merge disks are removed from a carrier. The pair of disks are repositioned into a concentric contact merge orientation. The outwardly facing surface of each disk in the pair, the R-side, is then subjected to some form of texturing, including data zone texturing or laser zone texturing. The disk pair is then demerged into a gap merge orientation and returned to the carrier. Another pair of disks is then removed from the carrier and the process is repeated. 
     To prevent relative movement or slippage between the disks during data zone texturing, it may be desirable to submerge the disk carrier in a liquid, such as water, in order that a liquid film is positioned between the disks prior to merging the pair of disks into a concentric contact merge orientation. The liquid film will act as an adhesive and facilitate unified movement of the disks. This promotes consistent and uniform texturing of each disk. 
     While the pair of disks are preferably in a concentric contact merge orientation during texturing, they may alternatively be positioned in a gap merge orientation. However, because pressure is applied to the outer surface of each disk in the disk pair during the data zone texturing process, a spacer merge orientation may be necessary for this process. Because laser zone texturing does not involve applying any physical force to the surface of the disks, spacers would not be required. 
     There are generally two data zone texturing techniques: fixed abrasive texturing and free abrasive texturing. In fixed abrasive texturing or free abrasive texturing with slurry, diamond particles, coolant water, strips of paper or fabric embedded with fine grit are brought in contact with and pressed against the outwardly facing surface (R-side) of each disk in the pair. In free abrasive texturing, a rough woven fabric is brought in contact with the R-side of each disk in a pair in the presence of a slurry. The slurry contains diamond particles for texturing the disk surfaces, a coolant to reduce heat created during texturing and a deionized water base solution. In the case of laser texturing, a laser beam is focused on desired locations of the disk surface and no mechanical force is applied against the disks. The disks are rotated in unison and the R-side surface of each disk is thereby textured as desired. Upon completion of the texturing, the disks are demerged. 
     The demerge methods and apparatus may vary depending upon how the disks are textured. This is primarily due to the fact that the force required to separate or demerge disk pairs is proportional to the force applied against the disks during texturing. In other words, disks which are pressed or forced together are harder to separate than disks that are not forced together. Thus, because the data zone texturing process applies a relatively large force against the disk surfaces, a relatively large force is needed to separate the disks. To reduce the possibility of damaging the disks, the demerge force is preferably spread or dispersed over a larger area of the disk perimeter by configuring the demerge tool to act upon a greater surface area. Conversely, because the forces applied to the disk surfaces during laser zone texturing are substantially smaller, the demerge tools can be smaller and can apply a smaller force over a smaller area of the disk perimeters. 
     In one embodiment, the demerge tool is wedge-shaped and engages the contact merge disks at their interface. In the case of data zone texturing, a pair of wedge-shaped demerge tools engage the disk pair from opposite directions along a substantial portion of the outer perimeter of each disk pair. In the case of laser zone texturing, the demerge tools may be smaller rollers with a W-shape in cross-section. The W-shape creates a similar wedge which is used to separate the disks. Any number of such rollers may be used, although three or four are preferable for not only demerging but for controlling the pair of disks following the demerge procedure. In a second embodiment, applicable only to data zone texturing, the demerge tool may comprise one or more nozzles which direct a focused stream of water at the interface of the disk pair. 
     The above-described embodiments and configurations are not intended to be complete nor exhaustive. As will be appreciated, other embodiments of the invention are possible utilizing, alone or in combination, one or more features set forth above or described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic of a double-sided disk manufacturing process, on the left, and a schematic of a single-sided disk manufacturing process, on the right. 
         FIG. 2  is a cross-section of a pair of gap merged disks. 
         FIG. 3  is a cross-section of a pair of concentric contact merged disks. 
         FIG. 4  is a cross-section of a conventional double-sided process disk. 
         FIG. 5A  is a front elevation view of an apparatus for handling disk pairs, with a pair of disks removed from a cassette. 
         FIG. 5B  is a cross-sectional view taken along the line  5 B— 5 B of  FIG. 5A . 
         FIG. 6  is an enlarged view of a portion of the apparatus for handling pairs of disks shown in  FIG. 5B . 
         FIG. 7  is a front elevation view of the apparatus for handling pairs of disks shown in  FIGS. 5A and 5B . 
         FIG. 8  is a cross-sectional view of the apparatus of  FIG. 7  taken along line  8 — 8  of  FIG. 7 . 
         FIG. 9A  is an enlarged view of the upper portion of the disk handling apparatus of  FIG. 8 . 
         FIG. 9B  is an enlarged view of the upper portion of an alternative embodiment of the disk handling apparatus shown in  FIG. 9A . 
         FIG. 10A  is a front elevation view of a second apparatus for handling pairs of disks. 
         FIG. 10B  is a side elevation view of the disk handling apparatus shown in  FIG. 10A . 
         FIG. 11  is an enlarged view of a portion of the disk handling apparatus shown in  FIG. 10B . 
         FIG. 12  is a plan view of a roller for engaging pairs of disks. 
         FIG. 13  is a top elevation view of the disk handling apparatus shown in  FIG. 10A , further showing a disk carrying cassette and a spindle for engaging disk pairs. 
         FIG. 14A  is a front elevation view of a pair of disks engaged at their central aperture by a spindle. 
         FIG. 14B  is a side elevation view of the disks and spindle shown in  FIG. 14A . 
         FIG. 15A  is a side elevation view of the spindle shown in  FIGS. 14A and 14B , but extended to permit engagement with a pair of disks. 
         FIG. 15B  is a front elevation view of the spindle of  FIG. 15A . 
         FIG. 16A  is a front elevation view of a pair of texturing rollers positioned to texture the surface of a disk. 
         FIG. 16B  is a side elevation view of a pair of texturing rollers positioned to provide data zone texturing to the surface of two disks. 
         FIG. 17A  is a front elevation view of a demerge tool for demerging a pair of contact merge disks. 
         FIG. 17B  is a left side elevation view of the apparatus of  17 A. 
         FIG. 18A  is a front elevation view of the demerge tool shown in  FIG. 17A , showing the demerge tool engaging a pair of disks. 
         FIG. 18B  is a right elevation plan view of the apparatus shown in  FIG. 18A . 
         FIG. 19  is a front elevation view of the demerge saddle shown in  FIG. 17A . 
         FIG. 20  is a top elevation view of the demerge saddle shown in  FIG. 19 . 
         FIG. 21  is a perspective view of the demerge tool shown in  FIG. 19 . 
         FIG. 22  is a cross-section view taken along line  22 — 22  of  FIG. 20 . 
         FIG. 23A  is a front elevation view of a disk handling apparatus positioned to lower a pair of disks from a demerge tool to a cassette. 
         FIG. 23B  is a side elevation view of the apparatus of  FIG. 23A . 
         FIG. 24  is an enlarged portion of the disk handling apparatus and demerge tool shown in  FIG. 23B . 
         FIG. 25  is a front elevation view of an alternative embodiment of a demerge tool, showing the demerge rollers engaging a pair of disks. 
         FIG. 26  is a side elevation view of a demerge roller engaging a pair of disks. 
         FIG. 27  is a cross-section view taken along line  27 — 27  of  FIG. 25 . 
         FIG. 28  is a side elevation view of a laser zone texturing apparatus. 
         FIG. 29  is a front elevation view of the demerge tool shown in  FIG. 25 , showing the demerge rollers disengaged from the disk pair. 
         FIG. 30  is a top elevation view of the demerge device tool of  FIG. 29 . 
         FIG. 31  is a top elevation view of the demerge tool shown in  FIG. 25 , further showing a retracted spindle. 
         FIG. 32  is a front elevation view of a demerge roller. 
     
    
    
     It should be understood that the drawings are not necessarily to scale. In certain instances, details which are not necessary for an understanding of the invention or which render other details difficult to perceive may have been omitted. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning to  FIGS. 5A ,  5 B, a cassette  10  is shown holding multiple pairs of gap merge disks D. The apparatus dimensions discussed herein relate to 95 millimeter diameter disks having a thickness of about 0.050 inches, unless otherwise stated. The spacing between disks of this size in a gap merge pair is preferably about 0.035 inches, although the space can extend from about 0.025 inches and larger. It should be understood that the apparatus and method of the present invention will work with disks of different diameters and thicknesses, in which case dimensions may vary from those stated herein. The gap merge orientation of the pairs of disks is best illustrated in  FIG. 5B . 
     As shown in  FIGS. 5A and 5B , one embodiment of a lift saddle  12  is utilized to remove and return pairs of disks from and to the cassette. The lift saddle  12  has an arcuate shaped disk engaging portion  14  comprising two channels or grooves  16  separated by a raised center ridge or tooth  18  ( FIGS. 6–9 ). The outer walls  20  of the disk engaging portion  14  support the outside edge of the disks. The saddle  12  includes two recesses or bores  22  positioned central to its body for receiving and securing push rods  24 . The push rods  24  move the lift saddle  12  between a first position beneath the cassette  10  and a second position extended through and above the cassette, as seen in  FIGS. 5A ,  5 B. As a result, the lift saddle  12  can remove and return pairs of disks from and to the same or a different cassette. 
     In the texturing processes it is preferable, although not required, to position the cassette  10  of disks in a tank of deionized water or similar liquid such that the disks are fully submerged. As discussed in greater detail below, in the preferred embodiment, the disk pair will be repositioned into a contact merge orientation. A liquid film between the disks helps prevent relative slippage of the disks during the texturing process. Placing the disks in a submerged environment allows a sufficient film to form on the disks and act as an adhesive when in a contact merge orientation. The cassette  10  is also positioned in an indexing apparatus, not shown, that incrementally moves the cassette as pairs of disks are returned from processing so that not-yet-processed disks are positioned for removal for processing by the lift saddle. 
     The push rods  24  will move the lift saddle  12  to a position where it will engage a first pair of gap merge disks and remove the pair to a position above the cassette ( FIGS. 5A ,  5 B). In the raised position, shown in  FIG. 5B , the pair of disks will be engaged by additional processing equipment, discussed below. In the embodiment shown, primarily used in connection with data zone texturing, and in connection with a 95 millimeter diameter disks having a thickness of 0.050 inches, the flat portion  26  of each channel of the lift saddle has a width (W 1  in  FIG. 9 ) of approximately 0.046 inches. The center to center distance between the channels is 0.075 inches (W 2  in  FIG. 9 ). Therefore, the width of the center ridge  16  is 0.025 inches; this is also the gap distance between the L-side of each disk in a pair. The angle of the side walls  20  for each channel  16  is approximately 40 degrees, and the angle formed by the walls of the center ridge or tooth  18  is approximately 40 degrees. In the preferred embodiment, the disks include a chamferred outer perimeter edge that matches or closely matches the angle of the tooth and outer walls which permits the flat portion  26  to have a width less than the thickness of the disk. The dimensions of the disk engaging portion of the lift saddle can be altered to accommodate disks of different size, diameter and thickness. 
     In order to process two R-sides (active sides) simultaneously, the non-functional or non-active sides (L-sides) of the disk pair are preferably merged. For texturing, the disk pair is preferably positioned in a concentric contact merge orientation. It is preferable when texturing two disks simultaneously that there be no relative movement or slippage between the two contact merge disks. To enhance the ability of two disks to move in unison, i.e. not to slip relative to each other, a fluid layer is uniformly deposited between the inactive side (L-side) of each disk. The fluid layer acts as a binding agent to keep the disks together. This may be accomplished by submerging the disks in a pool of deionized water. When the lift saddle removes two disks from the cassette, the water will drain away, leaving the desired water or film layer on the surface of the disks. The layer is preferably between 0.1 and 10 microns thick. Because the disks are polished substrate disks at this point in the manufacturing process, the relative flatness of the surface will increase stiction between the two disks. 
     With reference to  FIGS. 10–13 , once a pair of gap merge disks are positioned above the cassette  10  by the lift saddle  12 , the pair is engaged by a plurality of rollers or grip fingers  28 . The rollers  28  are rotatably mounted on merge arms  30 . The merge arms  30 , in turn, are mounted for lateral movement on a rotatable housing  32 . As illustrated in  FIGS. 11 and 12 , the rollers  28  are shaped to remove the gap between the disks and create a concentric contact merge orientation, i.e., to merge the disks. More specifically, the channel  34  formed in the rollers has a flat base portion  36  having a width W 3  similar to that of the flat portion  26  of the channel  16  of the lift saddle  12  (approximately double thickness of a single disk). The beveled inside walls  38  are oriented at a preferred angle of approximately 94 degrees to accommodate the 45-degree chamfer in the outer perimeter edge of the disks and function to engage the pair of disks along their outer perimeter while the disks are simultaneously supported by the lift saddle  12  in a gap merge orientation. It should be appreciated that the angle of the rollers can change to complement the angle of the chamfer in the disk perimeter. As the merge arms  30  move laterally inwardly, the lift saddle  12  retracts. This lateral inward movement of the merge arms  30  moves the rollers  28  laterally inwardly and into engagement with the disks. As a result, the space between the pair of disks is removed. A flexible or plastic cup  40  is mounted on the housing  32  and applies an outward force F, seen in  FIG. 10B , which also facilitates removal of the gap between the disks and assists in squeezing some of the deionized water out from between the disks. The force applied by the cup is typically no more than ten pounds and further increases the stiction between the disks. The plastic cup may be used in either data zone texturing or laser zone texturing. The disks are also drawn together or merged by the capillary action created as the deionized water drains out from between the disk pair as the lift saddle  12  removes the disk pair from their submerged position in the cassette  10 . Although four rollers are shown, three rollers are sufficient to securely hold and merge the pair of disks and allow the lift saddle to retract. 
     Once the rollers  28  have securely grasped the disk pair and the saddle  12  has retracted, the housing rotates 90 degrees. (Clockwise in  FIG. 13 .) The disks are now positioned to be engaged by a spindle assembly  42 . The spindle assembly  42 , illustrated in  FIGS. 14A ,  14 B,  15 A,  15 B,  16 A and  16 B, is primarily used in connection with data zone texturing, although any suitable spindle assembly would work, and this spindle assembly could also be used for laser zone texturing. The spindle assembly  42  includes an expandable collette  44  positioned at the end of a spindle shaft  46 . The collette  44  includes a series of teeth or a jaw set  48  alternately offset to engage the internal edge  50  formed by the central aperture  52  of each disk. Thus, every other tooth engages one disk and the remaining teeth engage the other disk. The spindle assembly  42  further includes a longitudinally extendable cam shaft  54  with a camming member  56  disposed on the distal end of the shaft  54 . In operation, with the cam shaft  54  extended as shown in  FIG. 15A , the diameter of the collette  44  is less than the diameter of the central aperture  52  of the disks. When the cam shaft  54  is retracted, the cam member  56  interacts with inside of the collette  44  to expand the collette  44 , causing the teeth  48  to engage the internal edge  50  of the central aperture  52  of both disks. Alternatively, as shown in  FIGS. 14A ,  14 B and  15 B, some of the teeth  48  may extend through the central aperture  52  of both disks and engage the outer surface  58  of the outer disk to further facilitate securement of the disk pair and prevent disk to disk slippage. Once the spindle shaft  46  is secured to the disks, the grip fingers or rollers  28  release and the disk pair is fully supported by the spindle shaft  46  in concentric contact merge orientation. In the preferred embodiment, a flexible cup  40  is also utilized as a counterbalance to the spindle assembly  42 . The cup  40  is positioned on the housing  32  opposite the spindle assembly  42 . The cup  40  is hollow to allow the spindle assembly  42  to expand through the central aperture  52  of the disks. The cup  40  provides a surface which pushes against the disks to counterbalance engagement of the disks by the spindle. The cooperation of all elements creates a concentric contact merge pair of disks securely affixed to the spindle assembly  42 . 
     Once the pair of disks is secured on the spindle assembly  42 , the rollers  28  disengage and move away from the disks. The housing  32  then rotates back to its original position. Four texturing rollers  60  are then positioned as shown in  FIGS. 16A and 16B ; two on each side of the spindle and two in contact with each disk. If fixed abrasive texturing is utilized, an abrasive tape or fabric, not shown, is wrapped around the rollers  60 . The abrasive tape contains fine grit or diamond particulate. If free abrasive texturing is utilized, a rough woven fabric is wrapped around each roller and a slurry is applied to the fabric and rotating disks to texture the disks. The slurry contains diamond particulates to texturize the disk surfaces, coolant to maintain lower temperatures and a deionized water base solution. In either texturing process, each of the rollers  60  is pressed against a portion of a disk surface with approximately 2.75 pounds of force while the spindle assembly spins the pair of disks at approximately 1,000 revolutions per minute. This action textures the data zone of the R-side of each disk. Optimum texturing is achieved if the two disks do not slip relative to each other. The inward pressure on the disk pair created by the opposed action of the texturing rollers further increases stiction between the disks. 
     A demerge tool  62  is used to unload the pair of textured disks from the spindle assembly  42 . The demerge tool  62  is illustrated in FIGS.  13  and  17 – 22 . The demerge tool includes a pair of demerge saddles  64  that are mounted on the housing  32  such that they can move laterally relative to the housing to engage opposite outer perimeter edges of the disks. As best seen in  FIGS. 19 and 22 , the demerge saddles  64  include a curved portion  66 . The curved portion  66  includes a pair of parallel channels or grooves  68  with a ridge or wedge  70  separating the two channels. Similar to the lift saddle  12 , the channels  68  are curved to follow the radius of the disk pair. The channels  68  may have a V-shape in cross-section, or, as shown in  FIG. 22 , the demerge saddle channels  68  may have a flat bottom portion. The walls  72  of the channels  68  are angled to match the angle of the chamfer of the outer perimeter edge of the disks. Thus, if the disks have a 45-degree chamfer, the side walls  72  will be formed at about 90 degrees. 
     In addition to engaging the disk pair, a function of the demerge saddle  64  is to demerge the disk pair and reposition the disk pair from a concentric contact merge orientation to a gap merge orientation. Accordingly, the wedge  70  abuts the groove  74  formed by the chamfers of the abutting L-side disk surfaces ( FIG. 18B ). To successfully demerge the pair of disks, the demerge tool  62  must overcome the stiction between the pair of disks. In this circumstance, the stiction is increased due to the pressure applied against the disk surfaces, such as by the tape rollers  60  against the disks, due to the water layer between the disks and due to the relative flatness of the L-side disk surfaces. In this embodiment, the demerge saddles  64  are designed to apply up to approximately 10 pounds of force to demerge the disk pair, although it is preferred to use less force to minimize potential damage to the disks. The amount of force needed can be reduced by applying the demerge tool against a larger perimeter edge of the disks. The demerge tool  62  is also designed to support the disk pair in order to allow the spindle assembly  42  to disengage before the demerge force is applied. The lower, inwardly extending portion  76  of each demerge saddle  64  supports the disk pair after the spindle assembly  42  has disengaged ( FIG. 18A ). 
     With the disk pair securely engaged by the demerge tool  62 , the housing  32  rotates to position the demerge tool  62  above the cassette as shown in  FIGS. 23A and 23B . The lift saddle  12  raises and engages the lower perimeter edge of the disk pair. The gap merge spacing of the channels  16  of the lift saddle  12  correspond to the gap merge spacing of the channels  68  of the demerge saddles  64  as shown in  FIG. 22 . When the disk pair is re-engaged by the lift saddle  12  ( FIGS. 23A ,  23 B,  24 ), the demerge saddles  68  disengage. The lift saddle  12  lowers the disk pair and seats them in the cassette  10 . The cassette  10  then indexes to a new position and the lift saddle  12  engages and removes a new pair of disks from the cassette  10 . The preferred sequence has one pair of disks engaged on the spindle assembly  42  and being textured while a second pair that has just completed texturing is returned to the cassette and a new, untextured pair is loaded between the rollers  28 . 
     As previously stated, the present invention can also be utilized for laser zone texturing the R-side surfaces of the disks. In contrast, with laser zone texturing, the disk surfaces are not mechanically contacted. As a result, there is even less stiction between the disks. Therefore, the demerge tool  62  may be configured differently for a laser zone texture process than for a data zone texture process. 
       FIGS. 25–32  illustrate a second embodiment of a disk handling assembly  78 . This disk handling assembly is primarily designed for laser zone texturing operations, although it could also be used for handling disks at other points in the manufacturing process. In laser zone texturing, a pair of gap merge disks are engaged by a lift saddle  12  and removed from a cassette. The lift saddle, shown in  FIG. 9B , has subtle differences with respect to the disk engaging portion  14  compared to the lift saddle illustrated in  FIG. 9A  and is primarily intended for use in data zone texturing processes. In particular, outer walls  20  include an upper surface  20   a  and a lower surface  20   b . The upper surfaces of the opposed side walls form a 40-degree angle, the lower surfaces of the opposed side walls form a 20-degree angle. The interface between the upper surface  20   a  and lower surface  20   b  occurs at 0.040 inches above the flat portion  26  which forms the base of the channels  16  (H 1  in  FIG. 9B ). The width of each channel W 1  is 0.046 inches for disks having a thickness of 0.050 inches. The height H 2  of the center ridge  18  is 0.097 inches. The width of the center ridge W 3  is 0.045 inches. 
     The disk handling apparatus  78  of  FIGS. 25–32  can be used to engage and remove disks from a lift saddle  12 , such as shown in  FIG. 9B , and to return disks to a lift saddle  12  and is primarily intended for use in laser zone texturing. The disk handling assembly  78  includes two separate but identical disk handling mechanisms  80  positioned at opposite ends of a rotatable plate  82 . Thus, the disk handling assembly  78  can simultaneously handle two different pairs of disks. The rotatable plate  82  has a pivot point  84  at its center which allows the plate to move through a 180-degree motion moving each disk pair between a first and second position. The first position is located above a cassette such that a lift saddle can lift a pair of disks to the first position and the disk pair can be engaged by a first disk handling mechanism  80  disposed at one end of plate  82 . Simultaneously, the second disk handling mechanism  80 , disposed at the opposite end of the plate  82 , has transported a second disk pair to a second position for processing. When the processing is completed, the plate  82  rotates and the second disk handling mechanism returns the processed disks to the first position where the disk pair is loaded on the lift saddle  12  and returned to a cassette and the first disk handling mechanism  80  moves the unprocessed disks to the second position for processing. 
     The mechanism includes four gap rollers  86  rotatably mounted on arms  88  ( FIGS. 25 ,  27 ,  29 – 31 ). The arms  88  move laterally on a rotatable plate  82 , allowing the rollers  86  to engage and disengage the disk pair. A gap roller  86  is shown in  FIG. 32 . As shown, the roller  86  has a pair of channels  90  separated by a control wedge  92 . Each channel has a flat bottom portion  94 , although each channel could also be V-shaped in cross-section instead. As with the other rollers described herein, the angle formed by the inner side walls  96  and the walls  98  of the wedge  92  correspond to the angles of the outer perimeter edge chamfer of the disks. As shown in  FIG. 26 , the rollers  86  are designed to maintain gap merge orientation of the disks. 
       FIGS. 25 and 27  show a disk handling mechanism  80  engaging a pair of disks, such as following disengagement of the pair by a lift saddle  12 . In this context, the plate  82  will rotate the disk handling mechanism to the second or processing location for presentation of the disk pair to a spindle assembly  42 . As shown in  FIG. 31 , the disk assembly will engage the pair and position the disk pair for engagement by a spindle assembly  42  for subsequent processing. The disk handling mechanism  80  will disengage the disk pair, as shown in  FIGS. 29 ,  30 . As shown in  FIG. 28 , such processing may include laser zone texturing performed by a pair of laser beams  100 . The lasers perform laser zone texturing on the R-side surface of each disk. Following processing, the disk handling mechanism  80  will re-engage the disk pair ( FIGS. 25–27 ) and the spindle assembly  42  will disengage. As shown in  FIGS. 30 and 31 , the grip rollers  86  will position themselves at the outer perimeter of the pair of contact merged disks. The arms  88  will press inwardly on the disk pair, forcing the wedge  92  between the pair of disks. Because the stiction is less than that formed between the disks during data zone texturing, the gap rollers  86  are mechanically sufficient to demerge the disks, allowing the spindle assembly to fully disengage. In this embodiment, approximately four pounds of force applied by the gap rollers will demerge the disks. In contrast, because the stiction between the contact merged disk pair is greater in the data zone texturing context, the demerge tools  62  engage the disks over a much greater perimeter length than do the gap rollers  86 . The larger contact area provides greater mechanical leverage to more readily separate the contact merge pair. 
     The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the invention are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the invention. 
     Moreover, though the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g. as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.