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No Spin DVD

A DVD player that has no spinning mechanism.
(+3, -3)
  [vote for,

The problem with dvd players is that they have to spin for the laser in the read head to read them, and the disc can only spin so fast before it explodes (really!), my idea is to make a dvd reader that dosn't need to spin the dvd to read it. DLP (Digital LIght Processing) televisons use microscopic mirrors to move projected light to positions on the screen, adapting this technology to the dvd reader, the read head would fire its laser at the mirrors, the mirrors would reflect the beam to any spot on the DVD, and it would reflect, as normal, back to the mirrors and read head. The advantages of this would be a dvds read speed wouldn't be limited by the spin of the disc, the disc would be perfectly, but the speed of the mirrors, and since they are so small, it would be pretty damn fast, also the dvd could be any shape, round, square, oblate rectilinear spheroid (!?!), whatever, and if the DLP chips could be made cheaply ennough we could have dvd players (and recorders) with practicly no moving parts at all, cheap as hell and would last forever. Well there it is, tell me what you think.
Hirudinea, Jun 05 2009

5 Dimensional DVD http://news.bbc.co..../nature/8060082.stm
not quite the same, but interesting nonetheless [simonj, Jun 05 2009]

LowPower CD player LowPower_20CD_20player#1149278074
[xaviergisz, Jun 05 2009]

Some numbers on blue light Optical media http://www.memorex....lue_Laser_Jun06.pdf
Dimensional and data rate comparisons to CD, DVD/R etc. [csea, Jun 09 2009]


       Its good! It would allow colossal DVDs to be made because there would be no concern about the spin being too strong on the outer edge. I am thinking Yap Island big.
bungston, Jun 05 2009

       I'm pretty sure we've done this one a couple of times already (at least), in different guises. DLPs, being mechanical, have a pretty limited response.
AbsintheWithoutLeave, Jun 05 2009

       somebody tell me why they don't spin the head instead of the disc; could keep "explosions" to a minimum.
FlyingToaster, Jun 06 2009

       See the Peter Sellers Film "Running, jumping standin still" (on Youtube) in which a man places a gramaphone record on a tree stump and runs arround it with the pickup arm: Like this only faster. The dvd won't explode. With lab centrifuges they get over this problem by spinning in a vacuum.
giligamesh, Jun 06 2009

       //The dvd won't explode// if you keep it under 72x or so, but why waste the energy moving a 16g CD when you can move a <1g rw head/arm ? Since that would be capable (I imagine) of moving much faster, you could get "72x" from start to finish as CLV instead of rat's-ass CAV... could use centrifugal momentum (err centripetal?) as well as you moved the head in and out.
FlyingToaster, Jun 07 2009

       //With lab centrifuges they get over this problem by spinning in a vacuum// are you saying it is air friction that kills the DVDs at high speed, rather than centripetal forces?
loonquawl, Jun 07 2009

       +1 Cheap and very high capacity solid state with incredibly fast read speeds. Would this system allow them to be written to?
DIYMatt, Jun 08 2009

       //Wonder how many megabytes on a DVD there are in the area of one old punch tape hole// About two-and-a-half. (assuming 4.6GB/DVD and a one-tenth of an inch diameter hole)
coprocephalous, Jun 08 2009

       I was wondering how this might work. My best guess is to have a laser firing through the hole in the middle of the stationary DVD onto a rotating mirror. Then, changing the angle of this mirror from the horizontal would cause the laser to be reflected onto particular tracks on the underside of the DVD. The beam would reflect off the DVD onto a cylindrical mirror wrapped aound the DVD and then onto a single detector mounted just below the rotating mirror and also vertically below the hole in the DVD.
hippo, Jun 08 2009

       [hippo]: that idea is great! the smaller circumference of the mirror would mean higher attainable speeds (as the mirror could be designed without as much an eye on cost as a DVD, still higher).   

       DVDs could come in any shape.   

       This seems very bakeworthy.
loonquawl, Jun 08 2009

       Double or triple wind the DVD and read it with multiple heads at a time.
vincevincevince, Jun 08 2009

       If this works well, a pretty big if, then it would be interesting to examine the optimimum topology or optimal topologies associated with different types of data access.   

       Certain topologies will be better for the RAM-type that [Ian...] alludes to. Others better for sequentially stored and accessed, like [hippo]'s simple parabolic reflector. Very interesting as a thought experiment.   

       However, in practical use, addressing becomes an issue. Not the actual address per se (you could have FAT 2^x for all I care), but rather how much energy and information is needed to access a specific address for the information you derive. With spinning disks and known position heads, we plot addresses by knowing the frequency of rotation of the medium, the position of the data on the "spiral", and the position of the reading head. And for the energy of getting the disk spinning and maintaning that rpm, and adjustments to the read/write head we receive a certain amount of data. Spinning the disk can be viewed as a "once off" energy input. No such efficiency is evident with the multiple mirror proposition. Unless you presume the read head is set in one position. In that case you eliminate a lot of the advantages of this idea.   

       Never mind the energy loss, we are also required, in this instance, to compute close to the readable data amount of information (about the mirrors, or at least convey that data to the mirrors) to get the information from this system. You must remember that current disk reading systems are fed data from known positions, from both information and "reader". This may not sound different from accessing the data from movable mirrors, but it is.   

       It is not sounding so good so far.   

       However, I do believe there are tricks, or methodologies, to mitigate at least the information obstacles. Energy obstacles are not my concern here, these have been dealt with before.
4whom, Jun 08 2009

       I like the idea of square media, or at least mostly square. The coordinates of the mirror in the x and y axis would give you your addressing with a 'reference mark' on each corner to let the reader know which direction the media was inserted. If it's not exactly square, then it would only go in 1 direction, reducing the space lost to reference marks. In this case, tracks would be positions along 1 axis, from one side to the other. No spiral or spin needed.
gryphon327, Jun 09 2009

       It seems to me that the most obvious way to implement this idea is to use a cylindrical "disk", with the data encoded on the inner surface.   

       For the reading device, a mirror would be mounted (at a 45 degree angle) on the end of a spinning shaft, whose axis would coincide with the cylinder's axis.   

       The shaft could be moved "up" and "down" the disk (corresponding to inwards and outwards) as data is read.   

       The "vertical" position of the shaft would be controlled in two ways -- firstly, by a motor for making gross position changes, and secondly by the motor spinning the mirror (but highly geared down).   

       The only real problem with this idea, is that you can't easily stack your "disks."
goldbb, Jun 09 2009

       I think there are several fundamental problems with getting this to work at all, (let alone in real or multiple x speeds.)   

       One problem has to do with the dimensions of the pits on the media. These are _small!_ (e.g. 0.62um width for HD DVD, 1.6um for plain old CD. "Blu-ray" DVDs are so called because a 405nm (0.4um) laser must be used to read the pits.   

       The optics that allow reading of pits of this extremely small size require lenses to be no more than a few mm from the disc surface; for Blu-ray, this becomes a few microns (um). It would be extremely difficult to fold the optical path to include a DLP mirror (current DPLs have mirrors of about 16x16um.)   

       Yet another problem is noise (in the optical, mechanical and electrical systems.) I am skeptical that this could be overcome.   

       As [bigsleep] suggests, data rate is going to be problematical. [Ian Tindale] proposes a "holographically high resolution ... sensor" to read all 15-20GB (that's Bytes) at once. Let alone the original poster's "cheap as hell." 8( Sounds like magic to me!   

       Of course, as I. Asimov says, "Any sufficiently advanced technology is indistinguishable from magic."
csea, Jun 09 2009


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