Mailing machine including shutter bar control system

Abstract

A mailing machine base adapted to have a postage meter mounted thereon, wherein the meter has a postage printing drum and a drive gear therefor, and wherein the meter has a shutter bar movable in opposite directions through a predetermined distance for movement thereof out of and into locking engagement with the drive gear, the base comprising, structure for moving the shutter bar, a d.c. motor for driving the shutter bar moving structure, a microprocessor, including a program power switching structure connected between the microprocessor and d.c. motor, the switching structure including four power switches arranged in an H-bridge circuit configuration for driving the motor in opposite directions respectively corresponding to the opposite directions of movement of the shutter bar, and the microprocessor program including means for: (i) energizing the switching structure with a first signal for driving the d.c. motor in a given direction for a first time interval predetermined to cause the d.c. motor to move the shutter partially through the predetermined distance, (ii) energizing the switching structure with a second signal for driving the d.c. motor in the given direction for a second time interval predetermined to cause the d.c. motor to move the shutter bar substantially through the remainder of the predetermined distance, (iii) energizing the switching structure with a third signal for driving the d.c. motor in the direction opposite to the given direction for a time interval predetermined to cause the d.c. motor to decelerate movement of the shutter bar, and (iv) energizing the switching structure with a fourth signal for driving the d.c. motor in the given direction for a fourth time interval predetermined to move the shutter entirely through the remainder of the distance.