Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:

> 
> the hp3d has 300x300 dpi.
> i don't think this would work.
> but it would really be nice to simply print to a normal lj.
> 
> (in a laser printer, how is the laser deflected in the horizontal?)
> 
> you would also have to adopt all the paper sensors for x/y exposing.
> 
> regards
> stefan
> 

Actually, the resolution depends upon a lot of things.  It might have
been limited by the optics, or it might have been limited by the
control circuitry (e.g. memory for the bitmap, processing speed, etc.).

The laser is deflected horizontally by a servo-motor-driven spinning
mirror (I think it's a hexagonal mirror in the LJIII).  If I recall
correctly, the speed is set by a clock crystal, and the laser is
sychronized by sensing when it reaches a certain point of deflection
(at that point, it's reflected with a small mirror into a fiber-optic
cable that leads to a photosensor on the control board).

At first, I was thinking that the original LJIII control circuitry
could be fooled into doing all of my work for me by adapting the
paper-path mechanism to move the laser scanner down the length of the
PCB board, rather than its normal activity of moving the paper through
a printer.  I haven't given up on this notion, but it might be easier
and more robust to simply develop my own control interface for
managing the scanning mechanism and possibly do the image-to-bitmap
conversion in the attached computer.

Incidently, I understand that you can buy machines to do stuff like
this, along with ultra-sensitive photoresist to speed up the exposure
process.  The biggest problem, of course, is throughput: it's simply
faster for mass production right now to do everything with a mask.

Jonathan