Mailing machine including sheet feeding control means

A mailing machine base comprising:

• a. means for sensing a sheet fed to the base;
• b. a plurality of rollers for feeding the sheet;
• c. a d.c. motor for driving the rollers;
• d. a microprocessor;
• e. a comparator connected between the microprocessor and the d.c. motor for receiving therefrom a signal corresponding to the back e.m.f. voltage and providing the microprocessor with a comparison signal;
• f. a power switch connected between the motor and microprocessor;
• and
• g. the microprocessor programmed for:
• i. responding to the sensing means sensing a sheet fed to the machine to initially energize the power switch with a first signal for a first time interval predetermined to cause the d.c. motor to accelerate the rollers at a substantially constant rate substantially to a constant sheet feeding speed at the end of the first time interval,
• ii. providing a reference voltage signal to the comparator corresponding to a desired d.c. motor back e.m.f. voltage for causing the d.c. motor to drive the rollers at the constant sheet feeding speed,
• iii. determining whether the comparison signal indicates that the back e.m.f. voltage is greater than the reference voltage at the end of the first time interval and successively thereafter,
• iv. energizing the power switch with a second signal for a second predetermined time interval if the comparison signal indicates that the back e.m.f. voltage is not greater than the reference voltage and delaying said energization with the second signal if the comparison signal indicates that the back e.m.f. voltage is greater than the reference voltage, thereby causing the d.c. motor to drive the rollers at substantially the constant sheet feeding speed.

In a mailing machine including means for sensing a sheet fed thereto, a plurality of rollers for feeding the sheet, a d.c. motor for driving the rollers, a microprocessor, and a comparator for receiving a back e.m.f. voltage signal from the d.c. motor, a process for controlling the d.c. motor comprising the steps of:

• a. a providing a power switch between the motor and microprocessor;
• b. programming the microprocessor to respond to the sensing means sensing a sheet fed to the machine to energize the power switch with a first signal for a first time interval predetermined to cause the d.c. motor to accelerate the rollers substantially to a constant sheet feeding speed at the end of the first time interval;
• c. programming the microprocessor to provide a reference voltage signal to the comparator corresponding to a desired d.c. motor back e.m.f. voltage for causing the d.c. motor to drive the rollers at the constant sheet feeding speed;
• d. connecting the comparator to the microprocessor for receiving therefrom a signal comparing the reference voltage and back e.m.f. voltage;
• e. programming the microprocessor to determine whether the back e.m.f. voltage is greater than the reference voltage at the end of the first time interval and successively thereafter;
• f. programming the microprocessor to energize the power switch with a second signal for a second predetermined time interval if the comparison indicates that the back e.m.f. voltage is not greater than the reference voltage and delaying said energization with the second signal if the comparison indicates that the back e.m.f. voltage is greater than the reference voltage, thereby causing the d.c. motor to drive the rollers at substantially the constant sheet feeding speed.