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Posted by Bill Vermillion on 01/08/06 19:35
In article <2ru0s11o7is8s16nqeibt5stdigraqk7qm@4ax.com>,
Roy L. Fuchs <roylfuchs@urfargingicehole.org> wrote:
>On Sat, 07 Jan 2006 23:05:06 GMT, bv@wjv.com (Bill Vermillion) Gave
>us:
>
>>In article <lmqqr15hkqurje5139hjnjqitd6ck91qdf@4ax.com>,
>>Roy L. Fuchs <roylfuchs@urfargingicehole.org> wrote:
>>>On 5 Jan 2006 06:41:30 -0800, "NYC XYZ" <jack_foreigner@yahoo.com>
>>>Gave us:
>>>
>>>>
>>>>Gil wrote:
>>>>> "baked" ??
>>>>
>>>>
>>>>Okay, "sun-tanned."
>>>
>>
>>> Production discs do NOT get burned by a laser, they get STAMPED by a
>>>plastic stamping machine!
>>
>>Actually they are molded. Stamping went away with the 45's and
>>LPs. And it's amazing how dirty a pressing plant seems to be.
>>It's the carbon black added to the plastic that seems to be
>>everywhere.
>>
>>Bill
> It's a clear polycarbonate gob, which is stamped or pressed.
> Injection molding would introduce bubbles. No carbon black anywhere.
I know there is no carbon black in CD/DVD production. I was
talking about the time I was in a pressing plant and I did refer
to 45s and LPs. It's amazing how good records sounded when you see
the way they are made with so much hand labor.
Slap the label down, put on a hunk of black plastic, lower the
stamper while you inject steam into the plates backing the
stampers, let it sit for about 7-10 seconds, hit the cold water too
cool the plastic, raise the stamper, lift out the disk.
If you didn't let it sit long enough or get it hot enough you got
'non-fill' where the plastic did not go fully into the grooves
which gave you a noisy recording because of the small air-spaces
that never got plastic.
If you didn't cool it enough you cuold pinch the disk a bit and
ruin it.
I don't recall if they were then stacked on a spindle and then had
the flash trimmed, or if they trimmed the flash and then stacked
them.
As to 'molding' DVDs take a look at some of the sites for DVD
manufacturers.
Here is something from a press release a year ago.
----------
Archive Press Release
Release date: December 8, 2004
JVC Develops Eco-friendly DVD Disk Made from Cone Starch-based
Polylactide
Tokyo (JCNN) - Victor Company of Japan (TSE: 6792; "JVC") has
developed an eco-friendly DVD disk made from cone starch-based
polylactide.
The disk incorporates polyactide-based transparent plastic
for optical disk use, which JVC jointly developed with Toray
Industries, to improve the disk's heat resistance by about
15 deg C, compared to conventional disks. The new plastic
with superb optical properties can also be used for CDs, BDs
(Blue-ray disks), and other optical disks. This disk has minute
signal pits formed using the same injection molding method
that is used for conventional disks. JVC will exhibit the
eco-friendly disk in Eco Products 2004 to be held at Tokyo Big
Sight from December 9.
Copyright 2004 Japan Corporate News Network. All rights reserved
_________________________________________________________________
And from the neasia.nikkeibp.com web archives here is another
snippet on molding. You'll note that Pioneer can use injection
molding to get 35GB disks. I also include a couple of other pieces
from the same article. I try to check NEAsia out at least once
a month. Lots of really good info there.
--------
Next-Gen ROM Manufacture
Another issue attracting considerable interest in the
next-generation optical drive field is volume-production
technology, especially that which reduces cost. Pioneer Corp has
solved the basic technical problems involved in using injection
molding to press read-only disks with 25 Gbytes of capacity
per side. The firm uses the thin cover layer approach, and its
technology raises the possibility of enabling packaged media with
HDTV resolution movies in the near future. The firm has used
an injection molding system designed for existing DVD disks to
fabricate a 25-Gbyte read-only disk. Measured playback signal
jitter (Fig 2) is kept under 10%. The firm believes it is now
possible to make next-generation optical media without major
equipment modifications.
Lens Manufacture by Etching
There are also proposals for new volume-production techniques for
optical components. Sony, for example, has announced a plasma etching
technique for forming multiple lenses at once on a glass substrate.
The firm is first aiming to use this technology for the DVR-blue
specification.
The specification uses a combination of large and small aspherical
lenses to create an object lens with an NA of 0.85. Glass aspherical
lenses, however, suffer from excessive metal mold costs, and low
productivity because only a few can be made at a time.
The firm's newly-developed technology is capable of batch-forming
about 400 lenses on a single glass substrate two inches (about 50mm)
in diameter (Fig 3). The firm plans to eventually use an 8-inch (about
200mm) substrate to form thousands of lenses at once.
The firm has only developed a prototype of the smaller of the two
lenses, the one closest to the disk. Sony plans to increase the lens
diameter of the smaller lens along with the working distance (WD:
distance between disk and lens), and apply the same fabrication method
to the larger lens as well.
If both lenses are made with this volume-production technology, it has
the potential to significantly reduce optical pickup assembly cost as
well. The glass substrates, one with large lenses and the other with
small lenses formed, can be arranged vertically and semiconductor
wafer technology (adopted for positioning) can be used to batch-align
all the lenses at once.
Near-Field Recording
Now that some of the key technical problems are being resolved for
next-generation optical disks, researchers are beginning to address
the issues of how to boost areal recording density past HDD levels.
Already, densities of 50 Gbits/inch^ 2 , equivalent to that of
existing HDDs, have been achieved in experiments. At ISOM 2000, there
were a number of reports of similar densities under close-to-product
conditions, and of significantly higher densities as well. In
particular, there were many reports on nearfield technology.
For example, Sony has succeeded in recording and reading back data
using near-field technology with a solid immersion lens (SIL), while
performing tracking control. Near-field technology has finally taken a
big step from the demonstration of the recording and read principles
to the investigation of practical implementation in actual equipment.
An optical disk was fabricated with a land-groove structure, with
tracking control data in the grooves, and marks recorded to the land
tracks (Fig 4). The control method was the standard push-pull design.
The minimum recording mark length was 107nm, and record/read using
those marks showed a C/N ratio of 41dB. Areal recording density, as
calculated from the linear recording density, was equivalent to 40
Gbits/inch^ 2 . Track pitch was 360nm, however - wider than the 180nm
equivalent to that areal recording density.
Another issue attracting considerable interest in the next-generation
optical drive field is volume-production technology, especially that
which reduces cost. Pioneer Corp has solved the basic technical
problems involved in using injection molding to press read-only disks
with 25 Gbytes of capacity per side. The firm uses the thin cover
layer approach, and its technology raises the possibility of enabling
packaged media with HDTV resolution movies in the near future.
The firm has used an injection molding system designed for existing
DVD disks to fabricate a 25-Gbyte read-only disk. Measured playback
signal jitter (Fig 2) is kept under 10%. The firm believes it is now
possible to make next-generation optical media without major equipment
modifications.
--------
--
Bill Vermillion - bv @ wjv . com
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