Problem 3. Engineers at Hewlett-Packard have contracted your time to consult in the preliminary design
of a new industrial laser printer. Laser printers such as those manufactured by HP use a laser beam to
rapidly print copy pages. The engineers currently envision using a pivoting scanning mirror mounted to a
servo motor to position the laser beam. The motor's position will be controlled via a RC circuit consisting
of a variable 0-28 VDC source in series with a resistor and a 180 µF capacitor.
Laser
Pivotating
mirror
Drum
ionisator
Drum
Toner
Paper ionisator
(Image Credit: http://www.bbemg.be/en/main-emf/electricity-fields/uses-of-em-properties.html)
The engineers at HP have decided that the laser beam pointing control system must have a settling time
of $T_s = 293$ milliseconds to provide sufficient time for the toner to deposit onto the paper as it transits
across the drum. However, the engineers are not sure what resistor (or combination of resistors) to use
in the RC circuit to provide the required $T_s$, since the voltage source is variable between 0 and 28 V.
As the controls engineer hired to consult on the project, what is your recommendation?
