Steve,
Your memory serves you well. I have pulled encoder strips and the read head from several epson printers. They are 720 CPI which matches the 720 DPI resolution of the printer. I used those on my last CNC machine before using US Digital encoders (linear strips).
There was a DC motor attached to the axis that moves the print head and the encoder strip was just above the print head behind the belts.
So, to me the DC motor, coupled with the linear encoder is a servo motor.
Chris
--- In Homebrew_PCBs@yahoogroups.com, "alienrelics" <alienrelics@...> wrote:
>
> Interesting. Maybe I'm remembering some of the incorrectly, but I do recall encoder strips for DC motors moving the heads left and right.
>
> Hm.... I guess not the Epsons. I was remembering that incorrectly. You've got me there.
>
> HPs and Lexmarks, however, most definitely use encoder strips. Note that they still use steppers to move the paper. The DC motor is used to move the printhead.
>
> If it is being used as a servomotor, does it matter where the position sensor is?
>
> Steve Greenfield
>
> --- In Homebrew_PCBs@yahoogroups.com, "Paul Symansky" <symansky@> wrote:
> >
> > Steve,
> >
> >
> >
> > It's interesting that you say that. Out of the 25+ Epson and HP printers
> > I've torn down for parts, the vast majority use stepper motors over DC
> > servos. The ones that did use DC motors, but not necessarily servo motors,
> > used them for gross movement in the Y direction after being significantly
> > geared down.
> >
> >
> >
> > In general, stepper motors are far cheaper than true DC servo motors. DC
> > motors with separate optical encoders are a different story.
> >
> >
> >
> > Regards,
> >
> >
> >
> >
> >
> >
> >
> > Paul Symansky
> >
> >
> >
> > w: www.paulsymansky.com
> >
> > w: www.symtechlabs.com
> >
> >
> >
> > "Solum potestis prohibere ignes silvarum."
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>