Improved Pulse-Width Modulated Motor Control Technique
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Printer and typewriter print mechanisms, at the end of a print line, require short stopping distances and then a fast direction reversal. This causes rapid motor deceleration and acceleration, and results in undesirably large motor currents. Described is a technique whereby the reverse motion response of a direct current motor is improved by using an improved pulse-width modulated drive circuit. In present DC motor drive circuits, as shown in Fig. 1, the pulse-width modulation input is applied only to transistors 1 and 2, depending on direction. Transistors 3 and 4 are not pulse-width modulated, and are controlled by direction only. In Figs. 1 and 3, the DC motor is modelled as a series RLC circuit. When the mechanism is going to the left, capacitor 5 of this RLC circuit accumulates a charge in the direction shown.