Method of marking and detecting disc index
View Patent ↗The present invention allows placement of a disc at an angular orientation by marking the disc with an index mark or feature that can be detected, such as by a disc stacking machine used in a servo track writer. Either index is used to rotate the disc to the angular position. The present invention includes marking a disc surface with a mark or feature. An apparatus, such a stacking machine, will read the mark or feature to orient the disc in an angular position. The stacking machine will stack the positioned discs for servo track writing.
1. A method for stacking two discs into a stacked disc array comprising:
obtaining each disc comprising an index mark adaptively indicating a rotational position of the respective disc;
orienting each disc in relation to the respective index mark in a disc stacking machine;
writing servo information to each of the discs;
removing the discs from the disc stacking machine; and
reorienting each disc in relation to the respective index mark to define a preselected offset in the servo information between the discs while stacking the discs to form the stacked disc array.
2. The method of claim 1 wherein the reorienting step is characterized by a zero offset.
3. The method of claim 1 wherein the orienting step comprises rotating the discs until at least one index mark is detected.
4. The method of claim 1 wherein the reorienting step is characterized by a nonzero offset.
5. The method of claim 1 wherein the obtaining step is characterized by more than two discs.
6. The method of claim 1 wherein the obtaining step is characterized by an index pattern comprising a first mark and a second mark.
7. The method of claim 6 wherein the obtaining step is characterized by first and second marks that are radially disposed.
8. The method of claim 6 wherein the obtaining step is characterized by first and second marks that are tangentially disposed.
9. The method of claim 6 wherein the obtaining step is characterized by the index pattern comprising a third mark.
10. The method of claim 1 wherein the obtaining step is characterized by the index mark of at least one of the discs being made by laser etching.
11. The method of claim 6 wherein the obtaining step is characterized by the first mark and the second mark comprising different sizes.
12. The method of claim 9 wherein the obtaining step is characterized by the first mark and at least one of the second mark and the third mark comprising different sizes.
13. The method of claim 1 wherein the removing step is characterized by operably eliminating the disposition of the discs relative to each other defined in the orienting step.