Method for a tray exchange during continuous production of disks

#1. Field of the Invention

#This invention relates generally to a method of continuous production of disks that have a thin film coat and more particularly to a method of exchanging a disk tray after a film buildup has occurred without interrupting production of the couture.

#2. Description of the Prior Art

#FIG. 1 is a schematic representation of the coater and disk/tray handler used in the present invention.

#Referring to the drawing, there is generally disclosed at 10 a thin film coater. The coater may be any suitable coater such as a Unaxis Big Sprint Coater. The coater 10 includes a rotating disk loading mechanism 11. A disk/tray handler 20, having a rotatable table 21, is provided to position a plurality of disk trays 30, each containing six disks 40 proximate the disk loading mechanism 11. The disk/tray handler may be any suitable handler such as a Steag Hamatech disk/tray handler. The table 21 of the disk/tray handler 20 rotates between four positions, positions A through D. Position A may be referred to as a load position, position B a transfer position, position C an unload position and position D an intermediate position. The positions A through D are located at 0 degrees, 90 degrees, 180 degrees and 270 degrees on the table 21 of the disk/tray handler 20. The four disk trays 30 on the table 21 rotate between the positions A through D, as previously described. The disk trays 30 includes two halves that are separated and loaded with six disks 40. The disk tray halves are then reassembled at position A. Such disk tray halves are well known in the art. The table 21 of the disk/tray handler 20 is then rotated to position B. At position B, the disk tray 30 is taken by the rotating disk loading mechanism 11 and the disk tray 30, with the disks 40, are placed in the coater 10. The disk tray 30 is circulated through the coater 10 to coat a first side of the disks 40. The disk tray 30 is then removed from vacuum part of the coater by the coater disk load mechanism, grasped by the disk/tray handler, flipped 180 degrees, and replaced onto the coater disk load mechanism, loaded into the vacuum part of the coater to coat the second side of the disks 40. The disk tray 30 is again removed from the vacuum part of the coater by the coater disk load mechanism, grasped by the disk/tray handler, flipped 180 degrees and returned to the disk tray position B. The table 21 of the disk/tray handler 20 is rotated 90 degrees to move the disk tray 30, with the now coated disks 40, to position C. At position C, the disk tray 30 is separated into halves and the double-sided thin film coated disks 40 are removed by the Steag disk/tray handler and the tray reassembled. The table is then rotated to Position D. Position D of the disk/tray handler 20 is located 180 degrees from the position B where the disk trays 30 are loaded and unloaded from the coater 10. At position D, the trays are empty of disks 40.

#The disk trays 30 have a thin layer of film coated each time they cycle through the coater 10. Eventually the thin film builds up on the trays 30 to the point of flaking off, thereby causing debris detrimental to the disk performance. Alternately, the thin film would build up thick enough to shadow the outside diameter data area of the disks 40 during the coating which is detrimental to disk performance. Therefore, periodically the disk trays 30 that have a buildup of film coating need to be exchanged for clean disk trays 30. Normally this tray exchange has been done at an intermediate position of the rotating disk loading mechanism 11 of the coater 10. That is, as viewed in FIG. 1, the rotating disk loading mechanism 11 usually rotates between the coater and position B. However, when the trays 30 are exchanged, the disk loading mechanism 11 will rotate only 90 degrees and it is in that intermediate disk loading position that the trays 30 are exchanged. This is also the position where the masks for the larger disks were exchanged. However, if the tray exchange is done at the intermediate disk loading position of the coater 10, the disk tray 30 either has disks 40 that have been coated or it must not have been loaded with disks 40 from the disk/tray handler 20. If the tray 30 has disks in it when the exchange is made, there is a high probability that the disks 30 will be scrapped due to either damage by manual removal from the disk tray, contamination due to exposure to dust and debris or a lack of an easy way to place the disks back into the production flow. If, on the other hand, the tray was not loaded with disks 30 and is exchanged at the intermediate disk loading position of the coater, the tray will either have to have gone through the coater 10 without product disks or the tray introduced will have to go through the coater 10 without disks. The exchanging of the thin film coated trays 30 at the intermediate disk loading position of the coater 10 results in loss of production disks and/or results in interruption of continuous production. Further, when there is a shutdown or pause in the production to take the trays 30 out at the intermediate disk loading position, the temperature of the coater 10 may change and it is often necessary to go through the warm-up cycle again if the coater 10 cools off during the exchange. The warming up to reach equilibrium can take up to 20 minutes.

#The present invention is an exchange of the thin film coated trays with clean trays 30 at position D in the disk/tray handler 20. This exchange at position D allows for the continuous, uninterrupted production of disks 30. Further, it does not result in loss of product disks or production inefficiency. The handler 20 is at position D approximately 20 seconds which easily allows for the exchange of the clean tray 30 for the thin film coated tray 30 either manually or with a robot.