Wily & Ed, RW Q&A response plus ECD's RW machina....
(Thanks to you both for encouragement to this RW novice)
Wily:
1.a. Initialization should be incorporated into our roll to roll since other automated processes already use it.
It is a bulk process for batches for them but could be accomplished by a scanning laser towards the end of ECD's roll to roll line whose laser power and duration is tunable to the requirements of the particular phase change material being deposited (GeSbTe,AgInSbTe,AgVInSbTe or others). The latter, TDK's AVIST, has the claimed property of largely crystallizing onto the substrate during the amorphous deposition process reducing subsequent initialization time because of the material. Since it is a heat process, it could be done thermally through a radiant heater, skipping laser, and relying on bulk en-masse heating as well. Whichever way, the duration of initialization will have to be customized to the phase change mix/material going through the roll to roll machine which seems easily done.
1.b. As for lowering the cost of -RW to the cost of -R, I can only say maybe we'll get low enough that the market won't care. Phase changeRW does have a few extra steps: initialization to set the fresh disk up for recording and deposition of two extra dielectric layers that sandwich the phase change recording layer and
act as heat sinks to speed the quenching post melt and also the cooling during annealing (I think). So, I don't think RW media will match -R costs of production, but at some point the price differential won't be a deciding factor between the two IMO. (One is ideal for archival real-time unalterable recording and the other is ideal for rewrite/update/reuse/modification reflecting the changing focus of attention.
1.c. Formatting in the manufacturing process I think refers to creation of the surface architecture of the disk (I think) such as the spiral patterned grooves on the disk. It also refers (I think) to any pre-placed marks on the disk that might be used for tracking correction and clocking.
The groove widths,track pitch vary with each 'format', CD-RW, DVD-RAM, DVD-RW or DVD+RW.
These grooves in the disk are described (sometimes) as 'pregrooves' in the polycarbonate, the substrate, so I take that (cautiously) to mean that the grooves are pre-existing prior to the deposition of the subsequent layers.onto an RW polycarbonate substrate: dielectric layer then phase change recording layer, then 2nd dielectric layer, then reflective layer and protective layer. I think the polycarbonate in a liquid/molten state can be via injection/compression molding embossed under pressure inside the mold against an etched metal foil to yield a substrate with grooves, even cyclical wobbling grooves, and any clocking/addressing pits...
all of which can be done to an accuracy approaching 1/100th of a micron! So, the polycarbonate can receive these fine disruptions of its surface (=definition of embossing, or molding or carving) via injection/compression molding against such finely etched metallic foils, it is the liquid polycarb and the fine precision of etching capable with these foils (Ni based I believe)... which yields such finely embossed disks. After this molding/fine embossing then deposition begins, in batch process or for GE Ovonic in roll to roll serially through separate chambers for each layer (and initialization towards the end of the line).
2 Regarding ongoing conservative expectations....
4 M Inc, a Swiss manufacturer of rewritable disk manufacturing machinery with a recent deal with
Asahi, gives these production figures for their biggest machine: 8200 rewritable DVD single-sided disks/24 hours or 4100 rewritable DVD double-sided disks/24 hours or up to 3 million per year. All this is on Site: 4m-inc.com with details inside pdf docs.
So did Stempel say output is 1 disk/second (And, what kind of disk) at the shareholder's meeting?
If so, then 86,400 seconds/day or 31,536,000 disks per year per machina ;-)
Ed,
Wandering through the RW wilderness courtesy of google, I finally found a site worth shouting about:
Mansuripur's update on optical disk technology from April 1998, may sound old but for me better than any other. Ed, he addresses your MEMs point as a replacement for microactuators and his use of the language is brilliant... even I could understand most of it, most of the time. To encourage you and others, here are the areas covered in this well-illustrated paper: (#7 below is of passing interest)
itri.loyola.edu
1.Basic disk architecture and recording
2. Numerical Aperture
As NA increases:
the spot size decreases (wavelength-in-a-vacuum*/NA) where lambda is
wavelength in a vacuum
and depth of focus decreases (wavelength*/NA^2)
and coma aberration increases (wavelength*/NA^3)
and spherical aberration increases (wavelength*/NA^4)
3.Tracking feedback loops, vertical and horizontal explained
4. Laser and LED developments
5. MEMs for future, better tracking vs. microactuators
6. Polycarbonate birefringence properties vs. amorphous polyolephin.
7. "ECD is the tech. leader in phase change and optical media." This is one of the very scarce web references to ECD outside of govt. Grants and direct papers from ECD that I have run across in terms of optical media.
8. MO drives/media
9. Phase change media 'aging' = segregation,stress buildup, microcrack formation, etc.
10. Quick amorphisation, relatively slow crytallization, as the atoms must line up in formation, come to 'attention' in reveille terms
11. near field optics and solid immersion lenses reduce spot size
12. "Land and groove" recording (-RAM) vs. groove only recording (-RW,+RW)
13. Exchange-coupled magnetic multilayers -- "Alfranco" got left in the
dust on this one.
14. Stacked Optical disks and double layer disks
15. Copy protection references
and in conclusion Mansuripur says:
"Removability, backward compatibility andinterchangability carry with them a demanding burden, called 'standards' that must be agreed to by the entire industry. The customers demand this as they do not want a repeat of the VHS/Betamax situation a few years ago.
And he sees the future for optical disks involving:
1. blue laser
2. increased numerical aperture of the objective lens of the driver
3. near field optics
4. multilayer
(and one should add multilevel from Calimetrics now to his 1998 list.)
Mansuripur says with just items 1-4 above, increases of 50-100 fold are
not unreasonable to expect in the next 5-10 years.
Regards,
Al |
