Servodrive apparatus for driving the postage printing drum in a postage meter

Claim 2

In a postage meter having a postage printing drum mounted for rotation from and to a home position in single revolution increments and means for transporting individual pieces of mail, each at substantially the same speed with respect to each other, said pieces of mail being delivered into operative engagement with the incrementally rotating drum to be printed with postage at a fixed location on each of said pieces of mail, a servodrive apparatus for driving the drum and for controlling the angular velocity of the drum to be substantially equal to a preset angular velocity, said servodrive apparatus comprising: drive means for driving the printing drum; sensing means for sensing the angular displacement of the drum and for producing a signal proportional to the developed angular velocity; a signal generator for producing a signal proportional to the preset angular velocity; a comparator for receiving the signals of the signal generator and said sensing means for sensing the angular displacement of the drum and for producing a signal proportional to the developed angular velocity; a comparator for comparing the sensed angular velocity of the drum and the preset angular velocity; and control means operatively connected and responsive to said drum substantially at the preset angular velocity.

Claim 3

The servodrive apparatus for a postage meter as claimed in claim 1 wherein said sensing means comprises: a signal generator for producing a displacement signal proportional to the angular displacement of the drum; and a differentiating circuit connected to said displacement signal generator for producing a velocity signal proportional to the angular velocity of the drum.

Claim 4

The servodrive apparatus for a postage meter as claimed in claim 2 wherein said displacement signal generator comprises: means for generating a voltage; a potentiometer having a fixed resistance connected across said voltage generating means and a slider coupled to the drum to produce the signal proportional to the angular displacement of the drum.

Claim 5

The servodrive apparatus for a postage meter as claimed in claim 1 wherein said preset angular velocity comprises increasing, constant, and decreasing angular velocity phases, wherein said signal generator is connected to said comparator for producing a ramp signal proportional to the increasing velocity phase of the preset angular velocity.

Claim 6

The servodrive apparatus for a postage meter as claimed in claim 4 wherein said comparator comprises: a comparator amplifier to which said ramp signal generator and said sensing means are connected, said comparator amplifier being connected to said control means for producing a driving signal during the increasing velocity phase proportional to the difference between the ramp and velocity signals to regulate said control means.

Claim 7

The servodrive apparatus for a postage meter as claimed in claim 1 wherein said preset velocity comprises increasing, constant and decreasing velocity phases and wherein said signal generator is connected to said comparator for producing a run signal proportional to the constant velocity phase of the preset angular velocity.

Claim 8

The servodrive apparatus for a postage meter as claimed in claim 6 wherein said sensing means comprises: a feedback control circuit connected to said drive means for producing a feedback signal proportional to the angular velocity of said drive means and of the drum.

Claim 9

The servodrive apparatus for a postage meter as claimed in claim 7 wherein said comparator comprises: a comparator amplifier to which said run signal generator and feedback control circuit are connected, said comparator amplifier being connected to said control means for producing a driving signal during the constant velocity phase which is proportional to the difference between the run and feedback signals, for the purpose of regulating said control means.

Claim 10

The servodrive apparatus for a postage meter as claimed in claim 1 wherein said sensing means comprises: a signal generator for producing a deceleration control signal proportional to the angular displacement of the drum from the home position; a feedback control circuit connected to said drive means for producing a feedback signal proportional to the angular velocity of said drive means.

Claim 11

The servodrive apparatus for a postage meter as claimed in claim 9 wherein said preset velocity comprises increasing, constant, and decreasing velocity phases, and wherein said comparator comprises: an amplifier to which said deceleration control signal generator and feedback control circuit are connected, said amplifier being connected to said control means for producing a driving signal responsive to the deceleration control and feedback signals to regulate said control means to electronically detent the drum to the home position substantially at the decreasing velocity phase of the preset velocity.

Claim 12

The servodrive apparatus for a postage meter as claimed in claim 10 wherein said deceleration control signal generator comprises: means for generating a voltage; a potentiometer having a fixed resistance connected across said voltage generating means and a slider coupled to the drum to produce the signal proportional to the angular displacement of the drum from the home position; and an amplitude limited amplifier for amplifying the output signal of said potentiometer.

Claim 13

In a postage meter having a postage printing drum mounted for rotation from and to a home position in single revolution increments, means for transporting individual pieces of mail into operative engagement with the incrementally rotating printing drum to be printed with postage, means for generating a cycle start signal when each piece of mail passes a predetermined point in the transport means, a shutter bar for locking the drum at the home position, a shutter bar actuator responsive to the cycle start signal to unlock the shutter bar to permit rotation of the drum, and a reset actuator for resetting the shutter bar after the mail has been printed with postage; a servodrive apparatus for driving the drum and for controlling the angular velocity of the drum to be substantially equal to a preselected angular velocity, said servodrive apparatus comprising: drive means for driving the drum; a switch for starting said drive means when the shutter bar actuator operates to unlock the shutter bar; sensing means for sensing the angular displacement of the drum and for producing a velocity signal proportional to the developed angular velocity; signal means for producing a signal proportional to the preselected angular velocity; comparator means operatively connected to said sensing means and said signal means for generating an error signal proportional to the difference between the developed angular velocity and the preselected angular velocity; control means operatively connected to said comparator and responsive to the error signal, said control means for controlling said drive means to drive the printing drum substantially at the preselected velocity; and means for sensing when the drum has returned to the home position and for subsequently operating the reset actuator.

Claim 14

In a postage meter having a postage printing drum mounted for rotation from and to a home position in single revolution increments, means for transporting individual pieces of mail into operative engagement with the incrementally rotating printing drum to be printed with postage, means for generating a cycle start signal when each piece of mail passes a predetermined point in the transport means, a shutter bar for locking the drum at the home position, a shutter bar actuator responsive to the cycle start signal to unlock the shutter bar to permit rotation of the drum, and a reset actuator for resetting the shutter bar after the mail has been printed with postage; a servodrive apparatus for driving the drum and for controlling the angular velocity of the drum to be substantially equal to a preselected angular velocity, said servodrive apparatus comprising: drive means for driving the drum; a switch for starting said drive means when the shutter bar actuator operates to unlock the shutter bar; sensing means for sensing the angular displacement of the drum and for producing a velocity signal proportional to the developed angular velocity; signal means for producing a signal proportional to the preselected angular velocity; comparator means operatively connected to said sensing means and said signal means for generating an error signal proportional to the difference between the developed angular velocity and the preselected angular velocity; control means operatively connected to said comparator and responsive to the error signal, said control means for controlling said drive means to drive the printing drum substantially at the preselected velocity; and means for sensing when the drum has returned to the home position and for subsequently operating the reset actuator.

Claim 15

The servodrive apparatus for a postage meter as claimed in claim 12 wherein said preselected velocity comprises increasing, constant, and decreasing velocity phases, and wherein said signal means for producing a signal proportional to the preselected velocity comprises: a ramp signal generator connected to said comparator means for producing a ramp signal proportional to the increasing velocity phase; a run signal generator connected to said comparator means for producing a run signal proportional to the constant velocity phase; and a deceleration control signal generator connected to said comparator means for producing a deceleration control signal proportional to the angular displacement of the drum from the home position.

Claim 16

The servodrive apparatus for a postage meter as claimed in claim 13 further comprising: switching means for selectively, sequentially connecting said ramp, run, and deceleration control signal generators through said comparator means to said control means respectively during the increasing, constant and decreasing velocity phases of the preselected velocity.

Claim 17

The servodrive apparatus for a postage meter as claimed in claim 13 wherein said comparator means comprises: a first comparator amplifier to which said ramp signal generator and angular displacement sensing means are connected; and a second comparator amplifier to which said run and deceleration control signal generators, and first comparator amplifier are connected.

Claim 18

The servodrive apparatus for a postage meter as claimed in claim 15 further comprising: a first switch for selectively connecting said first comparator amplifier to said second comparator amplifier; a second switch for selectively connecting said run signal generator to said second comparator amplifier; and a third switch for selectively connecting said deceleration control signal generator to said second comparator amplifier.

Claim 19

The servodrive apparatus for a postage meter as claimed in claim 16 further comprising: a servodrive start signal generator coupled to the shutter bar actuator for starting said ramp signal generator to generate a ramp signal, for closing said first switch and for opening said second and third switches when the shutter bar is unlocked.

Claim 20

The servodrive apparatus for a postage meter as claimed in claim 16 further comprising: an acceleration cut-out network coupled to said ramp and run signal generators for closing said second switch and for opening said first and third switches when said ramp signal is greater than said run signal.

Claim 21

The servodrive apparatus for a postage meter as claimed in claim 16 further comprising: an end run signal genertor operable after the mail has been imprinted with postage and the constant velocity phase has been completed to close said second and third switches and to open said first switch.