CA2032071A1 - Mailing machine base - Google Patents

Abstract

ABSTRACT

In a machine including a d.c. power supply having an output voltage, and including a d.c. motor having a load connected thereto for driving thereby, there is provided apparatus for controlling the speed of the motor independently of variations in the load. The control apparatus includes the power supply output voltage being a rectified and unfiltered output voltage, a silicon controlled rectifier having an anode and a cathode and a gate, structure for providing a reference voltage to the gate of the rectifier, and structure for connecting the anode and cathode of the rectifier between the power supply and motor for energizing the motor.

Description

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M~ILING MACHINE BASE

BACKGROUND OF THE INVENTION

The present invention is generally concerned with a circuit for controlling the sp,e,e,,~,of,a,,d.c. motor, and more particularly with a motor speed,c,,ontrol circuit for use in a machine. ''' . .
As shown in U.S. Patent No. 2,934,009, issued April 26, 1962, Bach, et al. and assigned to the assignee of the present invention, there is described a mailing machine which includes a postage meter and a base on which the postage meter is removably mounted. The postage meter includes a rotary printing drum and a drive gear therefor which are mounted on a common shaft and normally located in a home position. The base includes a drive mechanism having an output gear which is disposed in meshing engage-ment with the drum drive gear when the postage meter is mounted on the base. The drive mechanism includes a single revolution clutch, having a helical spring, for rotating the drum from the home position and into engagement with a letter fed to the drum. Each revolution of the clutch, and thus of the drum, is initiated by a letter engaging a trip lever to release the helical spring. In the course of each drum revolution, the drum prints a postage value on the letter while feeding the same downstream beneath the drum as the drum returns to its home position. Thus the drive mechanism intermittently operates the rotary printing drum.

As shown in Ca'nad,an Pa,tent Application S~ial Na;2',00,8,964.4 for a Mailing Machine Including Improved Driving Means Circuit, filed January 31, 1990 by John R. Nobile and assigned to the assignee of the present invention, structure is disclosed for replacing the mailing machine drive mechanism of the prior art with a simplified, highly reliable and quietly operating mailing machine drive system "
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including a circuit for controlling operation of the drive system. Experience has shown that the control circuit is sensitive to variations in motor loading conditions, due to letters, mailpieces and other slleet materials of various thickness being fed by the mailing machine within the ranye of sheet materials that are desirably fed thereby. In particular, the drive system may not be accurately stopped at the end of a given single revolution of the drum.
Moreover, it is desirable that the drive system control circuit be insensitive to a wide range of possible supply voltage variations inasmuch as mailing machines are sold in the international market place where available supply voltages normally vary from 90 to 13~ volts depending upon the differing standards of nations. ~ccordingly:

An ob~ect of the invention is to provide a motor speed control circuit;

Another object is to provide means for controlling ~che speed of a d.c. motor independently of mechanical loading of the motor;

Another object is to provide means for controlling the speed of a d.c. motor independently of variations in supply voltage;

Another object is to provide a d.c. motor speed control module; and Another object is to provide a mailing machine base including means for controlling motion of a mechanical load.

SUMMARY OF THE INVENTION

In a mach:ine including a d.c. power supply having an output voltage, and including a d.c. motor having a load connected thereto for driving thereby, apparatus for controlling the speed of motor independ~ntly of variations .. : ,. . .
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in the load, the apparatus comprising: the output voltaye being a rectified and unfiltered output voltage; a silicon controlled rectifier having an anode and a cathode and a gate; means for providing a reference voltage t~ the gate of the rectifier; and means for connecting the anode and cathode of the rectifier between the power supply and motor _ for energizing the motor.

: BRIEF DESCRIPTION OF THE D~AWINGS

As shown in the drawings wherein like reference numerals designate like or corresponding parts throughout the several views:

FIG. 1 is a partially phantom, perspective, view of a prior art mailing machine, including a postage meter removably mounted on a base;

FIG. 2 is a partially schematic, perspective, view of the drive system according to the invention, including the drive mechanism and control system therefor, and relevant apparatus ~unctionally associated therewith;

FIG. 3 is a partially schematic, top, view of the control system of Fig. 2, showing the latching member thereof and its functional interfacing relationship with the remainder of the drive mechanism;

FIG. 4 is a plan view of the actuating member of the drive mechanism of Fig. 2;

FIG. 5 is a plan view of drive mechanism of Fig. 2 shown in its normal or at-ready mode of operation;

FIG. 5A is a side view of the rotary cam of the drive mechanism of Fig. 5;

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~ IG. 5B is a partial top view of the drive mechanism of fig. 5;

FIG. 6 is a plan view, similar to Fig. 5, showing the drive mechanism when the latching member th~reo~ has been moved to its unlatching position to release the control member for carryiny the actuating member out of locking relationship with the cam and causing the actuating member to actuate the motor switch;

FIG. 6A is a side view of the rotary cam of the drive mechanism of Fig. 6;

FIG. 6B is a partial top view of the drive mechanism of Fig. 6;

FIG. 7 is a plan view, similar to Fig. 6, showing the drive mechanism when the control member thereof has been partially pivoted by the rotary cam to permit the latching member to return to its latching position;

FIG. 7A is a side view of the rotary cam of the drive mechanism of Fig. 7;

FIG. 7B is a partial top view of the drive mechanism of Fig. 7;

FIG. 8 is a plan view, similar to Fig. 7, showing the drive mechanism when the control member has been fully pivoted by the rotary cam, released thereby and re-latched by the latching member;

FIG. 8A is a side view of the rotary cam of the drive mechanism of Fig. 8;

- FIG. 8B is a partial top view of the drive mechanism of Fig. 8;

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F'IG. 9 is a schematic view of the control circuit of Fig. 2 showing the components thereof when the drlve mechanism is in its normal or at-ready mode of operation as shown in Fig. 5, 5A and 5B;

FIG. 10 is a schematic view, similar to Fig. 9, of another embodiment of the solenoid operating circuitry of Fig. g;

FIG. 11 is a schematic view, similar to Fig. 9, of another embodiment of Fig. 9;

FIG. 12 is a schematic view, similar to Fig. 9 showing the motor speed control circuit, including a silicon controlled rectifier and structure for providing a reference voltage thereto, according to the invention;

FIG. 13a is a diagrammatic view showing a power supply output voltage Vs of a power supply according to the invention;

FIG. 13b is a diagrammatic view showing the SCR gate voltages VG of the control circuit of Fig. 12;

FIG. 13c is a diagrammatic view showing the SCR
cathode voltage Vc, for a given motor load and given power supply output voltage, in the control circuit of Fig. 12;

FIG. 13d is a diagrammatic view, similar to Fig. 13c, showing the SCR cathode voltage Vc for another motor load in the control circuit of Fig. 12;

FIG. 13e is a diagrammatic view showing the SCR
cathode voltage Vc for a another power supply output voltage in the control circuit of Fig. 12.

FIG. 13f is a partial diagrammatic view of Fig. 12 showing an alternate embodiment of the structure thereof : :
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for providing a reference voltage to the silicon controlle~
rectifier; and FIG. 13g is another partial diagrammatic view of Fig.
12 showing another alternate embodiment of the structures thereof for providing a reference voltage to the silicon controlled rectifier.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

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As shown in FIG. 1, the apparatus in which the inven-tion may be incorporated generally comprises a mailing machine 10 which includes a base 12, having a housing 14, and a postage meter 16 which is removably mounted on the base 12. When mounted on the base 12, the postage meter 16 forms therewith a slot 18 through which sheets 20, includ-ing mailpieces such as letters, envelopes, cards or other sheet-like materials, may be fed in a downstream path of travel 22.

The postage meter 16 (Fig. 1) comprises rotary printing structure including a postage printing drum 24 and a drive gear 26 therefor. The drum 24 and drive gear 26 are spaced apart from one another and mounted on a common drum drive shaft 28. The drum 24 is conventionally constructed and arranged for feeding the respective sheets 20 in the path of travel 22, which extends beneath the drum 24, and for printing postage data, registration data or other selected indicia on the upwardly disposed surface of each sheet 20. The drum drive gear 26 has a key slot 30 formed therein, which is located vertically beneath the drum drive shaft 28 when the postage meter drum 24 and drive gear 26 are located in their respective home positions. The postage meter 16 additionally includes a shutter bar 3~, having an elongate key portion 34 which is transversely dimensioned to fit into the drive gear's key slot 30. The shutter bar 32 is conventionally reciprocally mounted within the meter 16 for movement toward and away ~rom the drum drive gear 26, to permit moving the shutter :, . . . . : ~

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2~3207 1 bar's key portion 34 into and out of the key slot 30, under the control of the mailing machines base 12, when the drum drive gear 26 is located in its home position. To that end, the shutter bar 32 has a channel 36 formed thereinto from its lower surface 38, and, the mailing machine's base 12 includes a movable lever arm 40, having an angularly-shaped upper end 42, which extends upwardly through an aperture 44 formed in the housing 14. When the meter 16 is mounted on the base 12, the lever arm's upper end 42 fits into the channel 36 in bearing engagement with the shutter bar 32 for reciprocally moving the bar 32, to and between one position, wherein shutter bar's key portion 34 is located in the drum drive gear's key slot 30, for preventing rotation of the drum drive gear 26, and another position wherein the key portion 34 is located out of the key slot 30, for permitting rotation of the drum drive gear 26. And, for driving the drum gear 26, the base 12 includes a drive system output gear 46 which extends upwardly through another housing aperture 48 and into meshing engagement with the drum.gear 26.

The base 12 (Fig. 1) additionally includes sheet aligning structure including a registration fence 50 against which an edge 52 of a given sheet 20 may be urged when fed to the mailing machine 10. Further, the base 12 includes drive system trip structure for sensing sheets 20 fed to the machine 10, including a trip lever 54 which extends upwardly through another housing aperture 58 and into the path of travel 22 of each sheet 20 fed to the mailing machine 10. Moreover, the base 12 includes a conventional input feed roller 60, known in the art as an impression roller. The impression roller 60 is suitably secured to or integrally formed with a driven shaft 61.
And the shaft 61 is resiliently connected to the housing 14, as hereinafter set forth in greater detail, for causing the roller 60 to extend upwardly through the housing aperture 58 and into the path of travel 22 for urging each sheet 20 into printing engagement with the drum 24 and :~ ~ , .
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cooperating therewith for feeding the sheets 20 throuyh the machine 10.

For feeding sheets 20 (Fig. 1) from the mailing machine 10, the base 12 includes a conventional output feed roller 62, known in the art as an ejection roller. The roller 62 includes a cylindrically-shaped rim 62A and a coil spring 62B connecting the rim 62A to a hubbed, driven shaft 63. Thus the rim 62A is driven by the shaft 63 via the coil spring 62B. A~d the shaft 63 is rotatably connected to the housing 14, as hereinafter set forth in greater detail, for causing the roller 62 to extend upwardly through a further housing aperture 64 and into the path of travel 22. Moreover, the postage meter 16 includes a suitable idler roller 66 which is conventionally yieldably mounted, to accommodate mixed thickness batches of sheets 20, with its axis disposed parallel with the axis of the ejection roller 62, when the meter 16 is mounted on the base 12. As thus mounted, the idler roller 66 extends downwardly into the path of travel 22. Preferably, the .
idler roller 66 is also conventionally movably mounted for adjusting vertical spacing thereof from the ejection roller 62, to accommodate feeding a given batch of relatively thick sheets 20, such as a batch of envelopes which are each stuffed with a letter and inserts. Thus, the rollers, 62 and 66, are constructed and arranged to accommodate feeding sheets 20 of mixed thickness therebetween and in the path of travel 22 from the machine 10.

The base 12 (Fig. 1), and thus the mailing machine 10, includes an elongate impression roller carriage 67 which includes a pair o~ parallel-spaced side walls 67A, one of which is shown, and a lower wall 67B which extends between and is suitably secured to or integrally formed with the side walls 67A. The carriage 67 generally horizontally extends from the ejection roller shaft 63, and beneath and in supporting relationship with the impression roller shaft 61. More particularly, one end of each of the carriage side walls 67A is preferably pivotably attached to the .
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203207 l housing 14 so as to define parallel-spaced arcuately-shaped bearing surfaces 67C within which the ejection roller sha~t 63 is rotatably mounted. Moreover, the side walls 67A are conventionally constructed and arranged for rotatably supporting the opposed ends of the impression roller shaft 61. And, the carriage lower wa:ll 67B is preferably connected to the housing 14 by means of a depending spring 68. Further, the base 12 includes a driven gear 61A which is suitably fixedly connected to or integrally formed with the impression roller shaft 61. ~hus, the impression roller shaft 61 and drive gear 61A are both conventionally rotatably connected to the carriage 67. In addition, the base 12 includes a driven gear 63A which is suitably fixedly connected to or integrally formed with the ejection roller shaft 63. And, the base 12 includes an endless gear belt 69 which is looped about the gears 61A and 63A for transmitting rotational movement of the gear 61A to the gear 63A, whereby the ejection roller shaft 63 and the impression roller 60 are driven in timed relationship with one another. Moreover, the gears 61A and 63A, and the impression roller 60 and ejection roller 62, are relatively dimensioned for ensuring that the peripheral velocity of the ejection roller 62 is greater than the peripheral velocity of the impression roller 60, when neither of the respective rollers 60 and 62 are in engagement with a sheet 20 fed thereto. As thus constructed and arranged, when the impression roller 60 is urged downwardly, the impression roller drive shaft 61 and drive gear 61A therefor are urged downwardly as the supporting carriage 67 pivots d~wnwardly about the ejection roller shaft 63, against the force exerted on the carriage 67 by the spring 68, to provide a variable gap between the drum 24 and impression roller 60, to accommodate mixed thickness sheets 20. And khe spring 68 resiliently urges the carriage 67, and thus the impres-sion roller 60, upwardly against any downwardly directed force exerted on the impression roller 60, by a given sheet 20 fed beneath the postage meter drum 24, for urging mixed thickness sheets 20 into printing engagement with the drum 2~.

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2032~7~

The base 12 (Fig. 1), and thus the mailiny machine 10, also includes an intermittently operable, electromechanical, drive system 70 (Fig. 2) for driving the the mechanical load comprising shutter bar lever arm 40 (Fig. 1), output gear 26 and thus the postage meter drum 24, and the roller shaft 63 and thus the roller 60, preferably in timed relationship with one another, in response to movement of the trip lever 54 by a sheet 20 fed to the machine 10.

The drive system 70 (Fig. 2) is conventionally sup-ported by the housing 14 and generally includes a drive mechanism 72 and drive system operating apparatus 74. More particularly, the drive mechanism 72 (Fig. 2) comprises a plurality of interactive structures including control structure 76, actuating structure 78, drive mechanism latching structure 80 and rotary timing cam structure 82.
And, the operating apparatus 74 includes trip lever struc-ture 84, and, in addition, comprises a plurality of compo-nents, including a trip switch 86, trip solenoid 88, motor switch 90 and d.c. motor drive system 92, and a control circuit 94 to which the components 86, 88, 90 and 92 are electrically connected.

The control structure 76 (Fig. 2) includes a control member 100 which is conventionally pivotably mounted for rotation, in a generally vertically-extending plane, on a pivot shaft 102 which is secured to or integrally formed with the housing 1~. As viewed in its home position (Fig.
5), the control member 100 includes a vertically oriented, upwardly~extending, leg 104, a laterally-extending leg 106 and a depending leg 108. The upwardly-extending leg 104 acts as a cam, latch and stop, and includes a cam surface 110, latching surface 112 and a stop surface 114. The laterally-extending leg 106 acts as a cam follower and includes a cam follower surface 116. And, the depending leg 108 acts as a lever arm and includes upper and lower slots 118 and 120. The control structure 76 also includes upper and lower springs, 122 and 124. The upper spring 122 .. ..

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has one end located in the upper slot 118 for attachment thereof to the depending leg 108 and has the other end attached to the actuating structure 78. And, the lower spring 124 has one end located in the lower slot 120 for ; attachment thereof to the depending leg 108 and has the other end indirectly attached to the housing 14.
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The actuating structure 78 (Fig. 2) includes an actuating member 130 which is als~ conventionally pivotably mounted for rotation, in a generally vertically-extending plane, on the pivot shaft 102. The actuating member 130 (Fig. 4) includes an upwardly-extending leg which acts as a lever arm and, in particular, is the shutter bar actuating lever arm 40. In addition, the actuating member 130 includes opposed legs, 134 and 136, which laterally extend from the actuating lever arm 40, and a depending leg 138.
One of the laterally-extending legs 134 acts as a cam key and cam follower and is thus transversely dimensioned to act as a key and includes a cam follower surface 140. The . other laterally-extending leg 136 acts as a pivot limiter and motor switch actuator, and includes a travel limiting surface 142, which is conventionally formed for contacting a housing stop 143 (Fig. 5), and a motor switch actuating shoulder 144. And, the depending leg 138 acts as a lever arm and includes a lower slot 146 (Fig. 4) in which the aforesaid other end of the control structure's upper spring 122 (Fig. 5) is located for attachment th~reof to the depending leg 138.

The drive mechanism latching structure 80 (Fig. 2) includes an latching member 150 which is conyentionally pivotably mounted for rotation, in a yenerally horizon-tally-extending plane, on another pivot shaft 152 which is secured to or integrally formed with the housing 14. The latching member 150 (Fig. 3) has a plurality of lat-erally-extending legs including one laterally-extending leg 154 which acts as a lever arm and includes a trip solenoid shaft striking surface 155. Another of the laterally-ex-tending legs 156 acts as a leaf spring, and yet another of - : :
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the laterally-extendiny Legs 158 acts as a leaf spriny Plexure limiter. The leaf spring leg 156 and flexure limiting leg 158 extend substantially parallel to each other and define a longitudinally-extending slot 159 therebetween. And, still another of the laterally-extend-ing legs 160 acts as a cam follower and latch, and includes a cam follower surface 164 and latching surface 166.

The rotary timing cam structure 82 (Fig. 2) includes a generally annularly-shaped rotary cam 180, which is suit-ably secured to or integrally formed with a drive shaft 182. The drive shaft 182 (Fig. 5) is conventionally connected to the housing 14, as by means of a supporting frame 183 which is conventionally removably connected to the housing 14, to permit rotation of the cam 180 in a generally vertically-extending plane. As viewed from the end of the shaft 182 which extends inwardly of the housing 14, the cam 180 has an outer, peripherally-extending cam surface 184, which tapers inwardly toward the viewing end of the drive shaft 182 to accommodate camming engagement with the control member's cam follower surface 116. The cam surface 184, when thus viewed and also when viewed as extending counter-clockwise from a line "1" (Fig. 5A) passing through the average radius of the cam surface 184, commences at a radial distance "rl" from the axis of the shaft 182, spirals outwardly, and ends at a radial distance "r2" from the axis of the shaft 182. As thus constructed and arranged, the cam 180 also includes a radially-extend-ing surface 186 having an average radial width of the sum of r2 ~ r1~ Further, as thus viewed, the cam 180 has a generally annularly-shaped inwardly-facing cam surface 188, surrounding the drive shaft 182l and includes a slot 190 formed thereinto from the surface 188. The s.tot 190 is located vertically above the drive shaft 182, when the cam 180 is disposed in its home position, and is suitably dimensioned for receiving thereinto the actuating member's key-shaped, laterally-extending, leg 134. `! ' ' ,; , ! ': ' ' : ' ' ' ' ' '.' : ~' ' ' ' " ' . , ' 2 0:, ~ 7 ~.

The trip lever structure 84 (Fiy. 2) in~ludes a trip member 200 which is conventionally pivotably mounted for rotation, in a generally vertically-extending plane, on a pivot shaft 202 which is secured to or integrally formed with the housing 14. The trip member 200 includes an upwardly extending leg, known in the art as the trip lever 54, and a depending leg 204, which acts as a lever arm and includes a slot 206 formed therein. The trip lever 54 preferably includes an upper, laterally-extending, shoulder 208, having an arcuately-extending upper edge 210 which extends towards respective sheets 20 fed thereto for supporting and yuiding such sheets 20 into the path of travel 22 when the trip lever 54 is engaged and moved by such sheets 20. In addition, the trip lever 54 includes a lower, laterally-extending trip switch actuating shoulder 212. The trip lever structure 84 further includes a spring 214, having on~ end located in the depending leg's slot 206 and the other end conventionally connected to the housing 14.

The krip switch 86 (~ig. 2) is preferably a single pole double throw switch having two modes of operation.
The switch 86 is conventionally physically connected to the housing 14 for suitable location of the switch 86 relative to the trip lever's switch actuating shoulder 212, to allow the shoulder 212 to operate the switch 86 in response to movement of the trip lever 54. The switch 86 includes an operating lead 220 and two switch position, leads, 220A and 220B. When the switch 86 is in one of its modes of opera-tion, the leads 220 and 220A are electrically connected, whereas when the switch 86 is in its other mode of opera-tion, the leads 220 and 220B are electrically connected.

The trip solenoid 88 (Fig. 2) is preferably a conven-tional D.C. solenoid which includes a core or sha~t 230.
The solenoid 88 is conventionally physically connected to the housing 14 for suitably locating the shaft 230 relative to the latching member 150 to allow the shaft 230 to strike the surface 155 of the latching member 150 and pivot the i ! ' ` ' "' ~ ' ,; '' ' ' ~ ' ' . :
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20~2~7.1l latching member 150 against the force exerted thereon by the leaf spring 156, when the solenoid 88 is energized from the control circuit 94.

The motor switch 90 (Fig. 2) is preferably a single pole double throw switch having two modes of operation.
The switch 90 is conv~ntionally physically connected to the housing 14 for suitable location of the switch 90 relative to the actuating member lever arm's switch actuating shoulder 144, to allow the shoulder 14~ to operate the switch 90 in response to movement of the actuating member's lever arm 40. The switch 90 includes an operating lead 236 and two switch position leads 236A and 236B. When the switch 90 is in one of its modes of operation, the leads 236 and 236A are electrically connected, whereas when the switch 90 in its other mode of operation, the leads 236 and 236B are electrically connected.

The d.c. motor drive system 92 (Fig. 2) preferably includes a conventional two terminal, permanent magnet, d.c. motor 240 having an output shaft 242. However, without departing from the spirit and scope of the invention, the motor 240 may be a compound, or shunt, motor having more than two terminals, two of which are armature terminals corresponding to the armature terminals of the permanent magnet motor 240. The motor 2~0 is conventionally physically connected to the housing 14 via a gear box 244. The motor output shaft 242 is pre~erably connected, via a reduction gear train 246 within the gear box 244, to an output drive gear 248, which is suitably journaled to the gear box 244 for rotation. The drive system 92 additionally includes a timing cam drive gear 250 and gear belt 252. The cam drive gear 250 is suitably fixedly connected to or integrally formed with the cam drive shaft 182. Thus, the cam 180 is mounted ~or rotation with the drive gear 250. And, the gear belt 252 is endlessly looped about and disposed in meshing engagement with the drive gear 248 and cam drive gear 250. The drive system 92 further includes an ejection roller drive gear :. ;,'. . ' . .. ' ' ' :

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203~071 254 ~nd a clrive shaft 256 on which the gear 254 is conventionally fixedly mounted. The drive sha~t 256 is suitably rotatably connected to the housing 14 for conven-tionally connecting one end thereof to the ejection roller shaft 63A (Fig. l) and disposing the ejection roller drive gear 254 (Fig. 2) in meshing engagement with the gear belt 252, between the motor output drive gear 2~8 and timing cam drive gear 250. Moreover, the drive system 92 additionally includes the drive system output gear 46, (Fig. 2), which is suitably fixedly connected to or inteyrally formed with the cam drive shaft 182 for rotation therewith and extends upwardly through the housing 14 for engagement with the drum drive gear 26 (Fig. 1). Thus, the cam 180 is mounted for rotation with the output gear 46 (Fig. 1) and drive gear 26.

The control circuit 94 (Fig. 2) includes a conventional d.c. power supply 270. In addition, the control circuit 94 includes suitable trip control circuitry for interconnecting the trip switch 86, trip solenoid 88 and power supply 270 for energization of the solenoid 88 in response to operation of the switch 86. Preferably, the trip control circuitry is conventionally constructed and arranged such that in one mode of operation the switch 86 (Figs. 9, 10 and 11) is operated to electrically connect the switch leads 220 and 220B for energizing the solenoid 88.

In Fig. 9 and 11, the solenoid 88 is energized through a series connected capacitor 272, from the power supply 270. Thus the solenoid 88 is operated Eor a time period which corresponds, substantially, to the charging time constant of the R-C circuit defined by the capacitor 272 and internal resistance 274 of the solenoid 88. In the other mode of operation the switch 86 is operated to electrically disconnect the switch leads 220 and 220B for maintaining deenergization of the solenoid 88, and to electrically connect the switch leads 220 and 220A ~or discharging the capacitor 272 through a series connected : .
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resistor 276. In ei-ther of the embodiments (F:iy.9 or 11), the resistance value o~ the resistor 276 is preferably chosen to ensure that the capacitor 272 does not discharge sufficiently to permit the next operation of the switch 8 to energize the solenoid 88 before the completion of a single revolution of the drum drive year 26 or cam 180.
Thus the time constant of the R-C circuit defined by the capacitor 272 and resistor 276 is chosen to maintain the discharge interval of the capacitor 272 for a predetermined time period, preferably corresponding substantially to the time interval during which the drum drive gear 26 and cam 180 complete rotation thereof through a single revolution.
Accordin~ly, the trip switch 86 is disabled from energizing the solenoid 88 for a predetermined time period after any given energization thereof. Moreover, the resistance value of the resistor 276 is preferably chosen to ensure completion of discharge of the capacitor 272 before the next operation of the switch 86 which follows completion of a single revolution of the drum drive gear 26 or cam 180, to permit commencement of the next revolution thereof su~stantially immediately after completion of any given single revolution thereof. Thus the solenoid circuit is in its at-ready mode of operation upon completion of any given -single revolution but not during any given revolution thereof~

Fig. 10 differs from that of Figs. 9 and 11, in that the solenoid B8 is energized from the capacitor 272, which is connected across the solenoid 88 when the switch 86 is operated to electrically connect the switch leads 220 and 220B. ~gain, the solenoid 88 is operated for a time period which corresponds, substantially, to the charging time constant of the R-C circuit defined by the capacitor 272 and the internal resistance 274 of the solenoid 88. The embodiment shown in Fig. 10 also differs from that of Fig.
9 and 10 in that in its other mode of operation the switch 86 is operated to electrically disconnect the switch leads 220 and 220B and connect the switch lead 220 and 220A for charging the capacitor 272, through a series connected .... .~ . ~ . . . . .
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resistor 278, from the power supply 270. Thus, the charging time constant of the capacitor 272 is determined by the time constant of R-C c:ircuit defined by the capacitor 272 and resistor 278. In this embodiment (Fig.10) the resistance value of` the resistor 278 is preferably chosen to ensure that the capacitor 272 does not charge sufficiently to permit the next operation of the switch 86 to energize solenoid 88 before the completion of a single revolution of the drum drive gear 26 or cam 180.
Thus the time constant of the R-C circuit defined by the capacitor 272 and resistor 278 is chosen to maintain the charging interval of the capacitor 272 for a predetermined time period corresponding substantially to the time interval during which the drum drive gear 26 and cam 180 complete rotation through a single revolution. Again, the trip switch 86 is disabled from energizing the solenoid 88 ~or a predetermined time period after any given energization thereof. Moreover, the resistance value of the resistor 278 is preferably chosen to ensure completion of charging of the capacitor 272 before the next operation of the switch 86 after the compl~tion of a single revolution of the drum drive gear 26 or cam 180, to permit commencement of the next revolution thereof substantially immediately after completion of any given revolution thereof. The solenoid circuit is in its at-ready mode of operation upon completion of any given single revolution thereof but not during any given revolution thereof.

Further, the control circuit 94 (Fig. 2) includes suitable motor control circuitry for interconnecting the motor switch 90, d.c. motor 240 and power supply 270 for energization and deenergization of the d.c. motor 240 in response to operation of the switch 90. Preferably, the motor control circuitry is conventionally constructed and arranged such that in one mode of operation the switch 90 (Figs. 9 and 11) is operated to electrically disconnect the leads 236 and 236A, for opening a shunt circuit across the d.c. motor 240, and to electrically connect the switch leads 236 and 236B, for energizing the d.c. motor 2~0 from ~: ~ ' , :
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-the power supply 270. And, in the other mode of operation the switch 9o operated to electrically disconnect the switch leads 236 and 236B, for deenergizing the d.c. motor 240, and to electrically connect the switch leads 236 and 236~, for closing the shunt circuit across the d.c. motor 240 for dynamically braking the d.c. motor 240. In the embodiment shown in Fig. 9, the shunt circuit is a simple short circuit, whereas in the embodim~nt shown in Fig. 11, the shunt circuit includes a capacitor 280 and a diode connected in parallel with one another across the motor 240. When the switch 90 is in its at-ready mode of operation as shown in Fig. 11, the switch leads 236 and 236B are disconnected for disconnecting the motor 240 from the supply 270, and the switch leads 236 and 236A connected for connecting the shunt circuit 280, 282, across the motor 240. In addition, the cathode of the diode 282, the side of the capacitor 280 connected thereto and the negative terminal of the motor 240 are connected directly to the ground of the power supply 270. And, the anode of the diode 282, positive terminal of the motor 240 and other : : -side of the capacitor 280 are also electrically connected to the ground of the power supply 270 via the series connected resistor 284, capacitor 272 and solenoid 88.

When the trip switch 86 is operated to connect the switch leads 220 and 220B for energizing the solenoid 88 via the capacitor 272, the side of the capacitor 280 connected to the anode of the diode 282 is connected via the switch 86 to the negative voltage source of the power supply 270, for appropriately charging the capacitor 280 to subsequently discharge through the motor 240 for dynamically braking the motor 240. .Thereafter, when the motor switch 90 is operated to disconnect the switch leads 236 and 236A and connect the switch leads 236 and 2368, the motor 240 is energized and the capacitor 280 charges and remains charged as the motor 240 is driven from the power supply 270. On the other hand, when the motor switch 90 is subsequently operated to disconnect the switch leads 236 and 236B, for deenergizing the motor 270, and to connect ;:: .
' _ L9 _ ~ 2032~71 the switch leads 236 and 236A, for connecting the capacitor 280, and diode 282 across the motor 240, the capacitor 280 discharges through the motor 240 causing current to flow in the motor 2~0 in the appropriate direction, that is, opposite to that of the motor operating current, for dynamically braking the motor 240. Preferably, the resistance value of the resistor 284 is selected to ensure that the capacitor 280 is discharged suf~iciently rapidly and to avoid causing the motor 240 to rotate in the wrong direction when the switch leads 220 and 220B are connected and the switch leads 236 and 236A have not as yet been disconnected, at which time the motor 240 is connected to the power supply 270 via the resistor 284.

According to the invention, the control circuit 94 (Fig. 2) preferably includes the circuitry shown in Fig.
11, modified to provide the control circuit 94A shown in Fig. 12, which includes structure for controlling the speed of the motor 240 independently of variations in the supply voltage Vs and independently of variations in the motor load. To that end the control circui~ preferably includes a d.c. power supply 270A, having a full wave rectified, unfiltered output voltage Vs as shown in Fig. 13. However, without departing from the spirit and scope of the invention the output voltage Vs may be a half wave rectified unfiltered voltage.

As hereinafter discussed, the two, say first and second, armature terminals of the motor 240 are identified as positive or negative, although any other distinguishing notation could be used to signify that the motor 240 will rotate in a forward direction when motor's positive terminal is connected to the positive terminal of the power supply 240 for conveying a sheet 20 in the downstream path of t~avel 22 through tha machine 10.

As shown in Fig. 12, for controlling the speed of the motor 240, and, in particular, forward rotation thereof, the control circuit 94A preferably additionally includes a .: , . ...................................... .
. ~ ' " ,: ' ' .
. ~ - ' ' ' ' ' .

2~32~71 speed control circuit 300. The speed control circult 300 includes a silicon controlled rectifier (SCR) 302 having the anode 304 thereof connected to the power supply 270A, the gate 306 thereof connected to a source of supply 308 for providing a reference voltage VR, and the cathode 310 thereof connected to the motor switch lead 2~6B and thus to _ the positive terminal "+" of the d.c. motor 240 when the motor switch leads 236B and 236 are connected for energizing the motor 240 from the power supply 270A. The reference voltage supply 308 preferably includes a zener diode 312 having the anode 314 thereof connected to the power supply ground GND, and the cathode 316 thereof connected to the positive terminal "+" o~ the power supply 270A via a current limiting resistor 318 for protecting the zener diode 312. The diode's cathode 316 is also connected .
to the SCR's gate 306, via a current limiting resistor 320 for protecting the SCR's gate 306. In addition, the motor speed control circuit 302 preferably includes a filter capacitor 322, which is connected across the SCR's gate 306 and cathode 310 for preven~ing the SCR 300 from conducting due to voltage discontinuities impressed across the SCR's gate 308 and cathode 310 by the brushes of the motor 240.
Preferably the zener diode 312 is selected to provide a reference voltage VR of substantially 15 volts.

In addition, for ~ontrolling rotation o~ the motor 240 (Fig. 12) and, in particular, reverse rotation thereof, the control circuit 94A includes an improved motor shunt circuit for braking the motor 240. The shunt circuit preferably includes a zener diode 282A having the anode 282B thereof connected to the positive terminal "+" of the motor 240, when the motor switch leads 236 and 236A are connected, and having the cathode 282C thereof connected to the negative terminal "-"of the motor 240. Further, the capacitor 280A .is preferably an electrolytic capacitor 280A
having the negative side "-" thereof connected to the positive terminal 11+11 of the motor 240 and having the positive side "+" thexeof connected to the negative texminal "-" of the motor 240. As thus constructed and :' . ', , ~ .. . . .
.. . . .. ..
:. . . . : , ~ , ... . . .
, 2~32~71 arranged, the zener diode 2~2A regulates the voltaye across the capacitor 282 independently of variations in voltage of the unfiltered power supply 270~. Moreover, when the capacitor 280A completes discharging reverse current though the motor 240, the zener diode 282A shunts the brushes of the motor 240, thereby providing a shunt path for current generated by the motor 240, which would otherwise be harm~ul to the electrolytic capacitor 280A. Further, the provision of the shunt path aids in braking the motor 240 after discharge of the capacitor 280A.

As shown in Figure 12, ~or preventing interaction of the trip and motor control circuitry, the control circuit 94A preferably includes a first diode 340 connected in series with the resistor 284 and a second diode 342 connected in series with the solenoid 88. Preferably, the first diode 340 is appropriately poled to block current flow therethrough from the capacitor 280A, whereas the second diode 342 is appropriately poled to block current flow therethrough from the capacitor 272. As thus constructed and arranged, the diodes 340 and 342, individually and in combination with each other, effectively isolate the different voltage levels of the capacitors 272 and 280A, thereby preventing interaction of the solenoid and motor braking circuits.

Prior in time to operation of the mailing machine 10 (Fig. 1), the drive system 70 (Fig. 2) is in its normal or at-ready mode of operation, as shown in Figs. 2, 3, 5, 5A
and 5B. As thus shown, the trip lever 54 (Fig. 2) is held, by means of the spring 214, in engagement with trip switch 86, which acts as a travel limiting stop. Moreover, the trip lever shoulder 212 holds the switch 86 in its operat-ing mode wherein the leads 220 and 220~ are electrically connected for maintaining the trip solenoid 88 deenergized.
In addition, although the spring 124 (Fig. 5) is connected for urging the control member 100 out of its home position, the control member 100 is held in its home position by the latching member 154 (Fig. 3), against rotation by the :, . ... . :

: , . - ~
, , : ,.
: :~ . . .,, , :
?

- 22 - ~032V7~

spring 12~ (Fig. 5), since the latching member's latching surface 166 is held in engagement with the control member's latching surface 112 by the spring 124. When the control member 100 is thus held, the cont:rol member's cam surface 116 is located out of engagement with the cam 180.
Further, the actuating member 130 (Fig. 5 and 5A) is urged into locking relationship with the rotary cam 180, by the spring 122. And, the actuating member's lever arm 40 i5 held in engagement with the control member's latching surface 114 by the spring 122. As thus disposed, the actuating member's lever arm 40 positions the shutter bar key portion 24 (Fig. 1) in the drum drive gear slot 30, thereby locking the drum drive gear 30 and thus the drum 24 against rotation, positions the lever arm's key leg 134 (Figs. 5 and 5A) in the rotary cam's slot 190, thereby locking the cam 180 against rotation, positions the lever arm's stop surface 142 out of contact with the housing stop 143 and positions the motor switch actuating shoulder 144 out of engagement with the motor switch 90. When the actuating member 130 is thus held, the actuating member's cam surface 140 is located out of engagement with the cam 180. Since the latching member 154 ~Fig. 3) holds the control member lO0 in place against rotation by the spring 124 (Figs. 5 and 5B), the control member lO0 cannot pivot the actuating member's lever arm 40. Thus, the latching member 154 indirectly prevents actuation of the motor switch 90, holds the shutter bar lever arm's key portion 24 (Fig. l) in the drum drive gear slot 30 and holds the lever arm's key leg 134 (Figs. 5 and 5B) in the cam slot 90, whereby the drum 24 (Fig. 1) and cam 180 (Figs. 5 and 5B) are locked in their respective home positions. And, the motor switch 90 (Fig. 2) is maintained in its mode o~
operation wherein the leads 236 and 236B (Fig. 9 and 12) are disconnected for preventing the d.c. motor 240 from being energized ~rom the power supply 270, 270A, and wherein the leads 236 and 236A are connected for maintaining the shunt circuit across the d.c. motor 240, with the result that the d.c. motor 240 is maintained deenergized.

:
.- " ~ ' ' .

, 2032n7.l In operation, when a sheet 20 (Fig. 1~ is fed to the base 12, the operator normally uryes the sheet edge 52 into engagement with the registration fence 50 and in khe direction of path of travel 22, whereby the shee~ 20 is fed towards and into engagement with the trip lever 54. The force exerted by the sheet 20 (Fig. 2) against the trip _ lever 54 causes the trip lever 54 to rotate about the pivot shaft 202 against the force exerted by the spring 214. As the trip lever 54 rotates, the trip lever's shoulder 212 operates the trip switch 86, thereby interconnecting the switch leads 220 and 220B for energizing the solenoid 88 from the power supply 270. Whereupon the solenoid 88 (Figs. 9, 10, 11 and 12) is maintained energized during the time interval the capacitor 272 is being charged (Figs. 9, 11 and 12) or discharged (Fig. 10), as the case may be.
When the solenoid 88 is energized, the solenoid's core or shaft 230 (Fig. 2) strikes the latching member's surface 155 and exerts sufficient force thereagainst, for a suffi-cient time period, to cause the latching member 150 to rotate about the pivot shaft 152, against the force exerted by the latching member's leaf spring leg 156, as the leg 156 is flexed against the housing 14. As the latching member 150 rotates about the shaft 152, the latching member's latching surface 166 arcuately moves out of engagement with the control member's latching surface 112 (Fig. 6), thereby releasing the control member 100 and permitting rotation thereof by the spring 124. Concurrent-ly, the free end of the flexure limiting leg 158 (Fig. 2) bridges the slot 159 for engaging leg 156, to limit the flexure of the leaf spring leg 156. As the spring 124 rotates the control member 100, the control member 100 pivots the actuating member's lever arm 40 away from the cam 180, thereby moving the shutter bar key portion 34 (Fig. 1) out of the drum drive gear slot 30 to permit rotation of the drum drive gear 26, and thus the drum 24, moving the lever arm's key leg 134 (Figs. 5 and 5B) out of the cam slot 190 to permit rotation of the cam 180, moving the lever arm's stop surface 142 (Fig. 2) into contact with the housing stop 143, and moving the lever arm's shoulder ::' ~ ,, :
: . . ... . .
, ::

:

-- 2~ --2032~7 1 14~ into encJacJement with the motor switch 90 to ~ctuate the switch 90.

Preferably, the capacitance value of the capacitor 272 (Figs. 9, 10, 11 and 12) is conventionally selected to ensure that the motor switch 90 is actuated before the solenoid 88 is deenergized. Thus the capacitor 272 becomes su~ficiently charged (Figs. 9, 11 and 12) or discharged (Fig. 10), as the case may be, to cause the solenoid 88 to be deenergized after the motor switch 90 is actuated, although the switch leads 220 and 220B may be maintained electrically connected by the trip lever shoulder 212 (Fig.
2). Upon deenergization of the solenoid 88 the latching member 150 (Fig. 3) is rotated about the pivot shaft 152 by the leaf spring leg 156, thereby causing the latching member's cam follower surface 164 (Fig. 6B~ to be urged into contact with the control member's cam surface 110.

In general, when the switch 90 (Figs. 9, 11 and 12) is actuated, the switch leads 236 and 236A are electrically disconnected for removing the shunt circuit from across the d.c. motor 240, followed by the switch leads 236 and 236B
being electrically connected for energizing the d.c. motor 240 from the power supply 270, 27OA.

According to the invention, whether or not the motor switch 90 (Fig. 12) is actuated, during any given cycle of power supply output voltage V~ (Fig. 13a) the SCR's gate voltage VG (Fig. 13b) tracks the supply voltage Vs (Fig.
13a) until the supply voltage Vs is substantially equal to the breakdown or reference voltage VR of the zener diode 312. Whereupon thé SCR's gate voltage VG is clamped to the reference voltage VR by the zener diode 312 (Fig. 12) until the supply voltage Vs (Fig. 13a) falls below the reference voltage VR, at which time the SCR's gate voltage VG again tracks the supply voltage Vs In addition, according to the invention, when the motor switch 90 (Fig. 12~ is actuated, and the switch leads ~ "
:, . . .

:- , . . .
,;: : -.
. , : ~

- ~5 -203~071 23~ and 236B are electrically connec-ted, the positive terminal ll-tll of the d.c. motor 2~0 is connected to the SCR's cathode 310. Assuming the SCR's forward breakdown voltage is about one volt, when the anode voltaye VA
exceeds the cathode voltage Vc by about one volt, and the SCR's gate voltage VG is greater than the SCR's cathode voltage vc, ~he SCR 302 commences conducting, that is, switches to its "on" mode of operation or state. Thus, as shown in Figs. 13a and 13c, when the initial half cycle of supply voltage Vs is applied to the SCR's anode 304, the SCR 302 conducts when the SCR's breakdown voltage is exceeded and the gate voltage VG exceeds the cathode voltage Vc. ~hereupon, the SCR's cathode voltage Vc is directly applied to the d.c. motor 240. Therea~ter, as the cathode voltage Vc (Fig. 13c), and thus the motor voltage ~, tracks the supply voltage Vs (Fig. 13a), the motor 240 commences rotation and the motor speed MS gradually increases as the cathode voltage Vc increases. Moreover, since the motor's back em* VE is proportional to the motor speed MS the back emf VE also gradua~ly increa~es. At time t2, when the motor's back emf VE (Fig. 13c) is equal to the cathode voltage Vc, the SCR 302 ceases conducting, that is, switches to its "off" mode of operation or state.

It is noted that the SCR 302 is switched to its "off"
state later than the time tl, i.e., when the cathode voltage Vc Ealls below the reference voltage VR, since the SCR gate 306 (Fig. 12) loses control over the conduction cycle of the SCR 302 after causing the SCR 302 to com~ence conducting. Moreover, the effect of motor inductance and current on the SCR's cathode voltage Vc, when the SCR 302 is switched to its "off" state is shown in Fig. 13c, by means of dashed lines, as a negative voltage spike 400.
In order to simplify the discussion thereof and clarify Figs. 13c, 13d and 13e, the voltage spike 400, although present during each cycle, is not repeatedly shown. On the other hand, it is well known in the art that when an SCR
302 (Fig. 13a) is switched to its "off" state in a circuit application wherein the SCR's cathode 310 is connected - . . :, " : ':

. .

203207.1 directly to ~ d.c. motor 240, that the motor current and inductance give rise to a negative voltage spike 400, or discontinuity, having a time duration which incrsases with increasing values of current ancl inductance. AGcording to the invention it is preferable t:hat the d.c. motor 242 be a small d.c. motor, that is one having an inductance value and current rating which are low enough to ensure that the time duration of the aforesaid voltage spike 400 does not extend so far beyond the end of any given cycle of the power supply voltage Vs that the SCR gate 306 (Fig. 12) does not regain control over the conduction cycle of the SCR 302 during the next cycle of the power supply voltage Vs, for timely switching the SCR to its "on" state as hereinafter discussed. Accordingly, as shown in Fig. 13c, during the first cycle of the power supply voltage Vs it is preferable that the voltage spike 400 which commences development at time t2 is no longer present at time t3.

After the SCR 302 (Fig. 12) switches to its "off"
state, the motor speed Ms, and thus the back emf VE, commences decreasing due to motor coasting, and continues to decrease until time t3, when the second half-cycle of the supply voltage Vs, and thus the gate voltage VG, exceeds the motor back emf VE. When the gate voltage VG
exceeds the cathode voltage Vc, the SCR 302 is again caused to conduct, it being assumed that the voltage spike 400 is no longer present, as hereinafter discussed. Thus, at time t3, the motor speed MS again gradually increases as the cathode voltage Vc increases, until time t4 when the SCR
302 again ceases conducting, followed by the motor's back emf VE again decreasing as the motor speed MS decreases, until, at time t5, when the SCR 302 is again caused to conduct due to the gate voltage VG exceeding the back emf VE and cathode voltage Vc.

As noted above, motor speed M$ is not only controlled by the SCR 302 and reference voltage supply 308, but also by the interaction of the power supply voltage Vs and motor : .: . , .,,`: ,, :. :. '. . , - ' '- .' , : . :: , ~ : . :

: .

2032~7.~
back emf voltaye VE. Thus the motor 240 itself plays an active role in controlling the motor speed Ms.

As shown in Fig. 13c, the above discussion concerning operation of the motor control circuit during the second cycle of the supply voltage Vs, applies with equal ~orce to operation thereof during the third and fourth cycles of the supply voltages Vs. Thereafter, during the fifth cycle, the SCR gate voltage VG does not exceed the SCR cathode voltage Vc until motor coasting causes the motor back emf VE to fall below the reference voltage VR. Whereupon, at time t6, when the anode voltage VA exceeds the cathode voltage Vc by the SCR's forward breakdown voltage, and the gate voltage VG exceeds the cathode voltage Vc, the SCR 302 commences conducting and continues to conduct until the decreasing cathode voltage Vc is offset by the increasing back emf VE, thereby causing the SCR 302 to cease conducting at time t7. Again, the back emf VE then falls off in proportion to the motor speed MS until, during the `~
sixth cycle of supply voltage Vs, the SCR 302 and d.c.
motor 240 repeat operation thereof as in the fifth cycle.
As noted in Fig. 13c, the discussion concerning the operation of the motor control circuit during the sixth to ninth cycles corresponds to the operation thereof during the fifth cycle. Moreover, operation of the motor control circuit during the seventh through ninths cycles is repetitive, that is, in each cycle o~ the seventh through ninth cycles of the power supply voltage Vs the phase angle e at which the SCR 302 is switched to its "on" state is the same. And, the motor speed MS stabilizes at the speed at which the average motor back emf VE is substantially equal to the reference voltage VK.

As shown in Pig. 13c, the cathode voltage Vc i5 substantially equal to the anode voltage VA whenever the SCR 302 (Fig. 12) is conducting, it being understood that the SCR's forward breakdown voltage of about one volt is small in comparison to the peak voltage anode voltage VA.
Further, the cathode voltage Vc (Fig. 13c) i5 equal to the : :' . . :. '~c ............. .

.... .

.
.. : .: .

-- 2~3 --2~3~7~ -motor b~ck emf VE whenever th~ SCR 302 (Fig. 12) is not conducting. And, the cathode voltaye Vc is at all times equal to the motor voltage Mv.

The difference between Figs. 13c and 13d is that in Fig. 13d the motor speed Ms, and thus the ba~k emf VE, increases more gradually than it does in Fig. 13c, signifying that the load on the motor 240 (Fig. 12) is greater in Fig. 13d than it is in Fig. 13c. In the mailing machine 10 (Fig. 1) in which the motor control circuit of Fig. 12 is preferably embodied, the load on the motor 240 varies in relation to the thickness of the sheets 20 which are processed by the machine 10. Thus, Fig. 13c illustrates operation of the motor control circuit of Fig.
12 when a thin letter, mailpiece or like sheet 20 (Fig. 1) is fed through the machine 10, whereas Fig. 13d illustrates operation of the motor control circuit of Fig. 12 when a thick letter, mailpiece or like sheet 20 (Fig. 1) is fed through the machine 10. Further as might be expected~ it is noted that the phase angle el at which the cathode voltage stabilizes in Fig. 13d, when feeding a thin sheet 20, is greater than the phase angle e2 at which the cathode voltage Vc stabilizes in Fig. 13d, when feeding a thick sheet 20, due to more power being needed to feed thick versus thin sheets 20. On the other hand, a comparison of ~igs. 13c and 13d shows that the motor control circuit (Fig. 12) controls the speed of the motor 240 independently of variations in motor load.

- The difference between Fiys. 13c or 13d and Fig. 13e is that in Figs. 13d and 13e, the peak SCR cathode voltage VC is about 25 volts, whereas in Fiy. 13e, the peak SCR
cathode voltage Vc is about 30 volts. On the other hand, in Fig. 13e the motor speed Ms, and thus the back emf VE, increase and decrease as a function of the cathode voltage VC and motor load, as the case may be, until the motor speed MS is stabilized in the same manner as in Figs. 13c and 13d. That is, at a speed at which the average back emf VE is substantially equal to the reference voltage VR.

. . , , :

: ;: . . . .

2 ) 203207~.

Accordingly, a comparison oF the Figs. 13c or 13d with Fiy.
13e shows that the motor control circuit (Fig. 12) controls the speed of the motor 240 independently of variations in the amplitude of the output voltage Vs of the d.c. supply voltage 270A. In addition, as shown in Fig. 13e, the phase angle 03 at which the cathsde voltage Vc stabilizes may be greater than the phase angle ~ f stabilization thereof in Fig. 13c, since the cathode volt~ge Vc is greater in Fig.
13e than in Fig. 13c.

Fig. 13f shows an alternate embodiment of the source of supply 308 for providing a reference voltage VR, and differs from the supply 308 shown in Fig. 12 in that zener diode 312 and resistor 318 thereof are replaced by a conventional reference voltage source provided by the D.C.
power supply 270A.

Fig. 13g shows another alternate embodiment of the source of supply 308 for providing a reference voltage VR, and differs from the supply 308 shown in Fig. 12 in that the resistor 320 thereof is replaced by a potentiometer 320a (Fig. 13g), including a fixed resistor portion 320b connected across the zener diode 312 and a wiper arm 320c, and by a fixed resistor 320d, connected in series with the wiper arm 320c, which is connected to the cathode 306 of the SCR 302. As thus constructed and arranged the potentiometer 320a may be adjusted for changing the reference voltage VR to accommodate adjusting the level of the reference voltage VR and thus the speed MS (Fig~ 13c) at which the motor 240 (Fig. 12) is stabilized.

When the d.c. motor 240 (Fig. 2) is energized, the motor output shaft 242 drives the gear train 246 and thus tAe output drive year 24~. And, motor rotation of the drive gear 248 (Fig. 1) is transmitted by the gear belt 252 to the cam drive gear 250, ejection roller drive 254 and drive system output gear 46, for rotating, in timed rela-tionship with one another, the rotary timing cam 180, : - . - .
.. ~ .

2032~7:~

ejection roller 62 and thus the impression roller 60, and the drum drive gear 26 and thus the postage meter drum 24.

Accordingly, rotation of the trip lever 54 (Fig. 1) by a sheet 20 fed thereto eventuates in causing the drum 24 and impression roller 60 to commence rotating in timed relationship with one another for feeding the sheet 20 downstream in the path of travel 22 beneath the drum 24 and causing the ejection roller 62 to commence rotating for feeding sheets 22 engaged thereby from beneath the idler roller 66 and thus from the machine 10. Since the angular velocity of the ejection roller rim 62A is normally greater than the angular velocity of the impression roller 60, the peripheral velocity of the ejection roller 62 is greater than that of the impression roller 60, as a result of which the e~ection roller 62 tends to pull respeotive sheets 20 which are fed thereto from beneath drum 24 while the drum 24 and impression roller 60 are still rotating in engage-ment with the sheets 20. When the drag force exerted on the ejection roller rim 62A, by a sheet 20 engaged by the drum 24 and impression roller 60, exceeds the spring force exerted on the ejection roller rim 62A by the coil spring 62B, the ejection roller shaft 63 continues rotation and stores energy in the coil spring 62B as the ejection roller rim 62A slips relative to the shaft 63, until the drum 24 is no longer in engagement with the sheet 20. Whereupon, the coil spring 62B releases the energy stored therein by driving the ejection roller rim ~2A for feeding the sheet 20 from the machine 10. Moreover, the ejection roller 62 feeds the sheet 20 out of engagement with the trip lever 54. Whereupon the trip lever 54 is rotated about the pivot shaft 202 (Fig.2) by the spring 214, causing the trip lever's shoulder 212 to operate the trip switch 86 for disconnecting the switch leads 220 and 220B and connecting the switch leads 220 and 220A for returning the trip switch 86 to its at-ready mode o~ operation.

However, although the trip switch 86 (Fig.2) is returned to its at-ready mode of operation, as hereinbefore . .: ::, . : .
. ................................... .
.
. ~ .~ , . . .
.
: . . , - , "' ' '.' '''': ,` '' ' ' ' - , , 2~32~7~
discuss~d, the trip switch 86 is disabled from energiziny the solenoid 88 for a predetermined time period after any given energization thereof. Ancl, the time period preferably corresponds substantially to the time interval during which the cam 180 or drum drive gear 26 complete rotation thereof through a single revolution. Accordingly, if a next sheet 20 were fed to the machine 10 after return of the trip switch 86 to its at-ready mode of operation, but before completion of a single revolution of the cam 180 or drum drive gear 26, movement of the trip lever 40 by the sheet 20, sufficiently to operate the switch 86, would not result in energization of the solenoid 88. Thus the solenoid circuit i5 constructed and arranged to prevent the drive mechanism 72 from being double tripped during any given single cycle of operation thereof, thereby ensuring single revolution operation of the drive mechanism 72 and preventing sheets 20 from being jammed between the drum 24 (Fig. 1) and impression roller 60, and ejection roller 62 and idler roller 66.

As hereinbefore discussed, rotation of the trip lever (Fig. 1) by a sheet 20 fed thereto whirh does result in operation of the trip switch 86 for energizing the solenoid 88, also eventuates in causing the rotary timing cam 180 (Fig. 2) to commence rotating in timed relationship with the impression roller 60 (Fig. 1), drum 24 and ejection roller 66. When the cam 180 (Fig. 6) commences rotation, the actuating member 130 is held against the housing stop 143 due to the spring 124 having rotated the control member 100 when the control member 100 was released by the latching member 154. When the actuating member 130 is thus held by the control member 100, the actuating member's cam follower surface 140 is located in a plane which is slightly spaced apart from, and which extends substàntially parallel to, the rotary cam's camming surface 188 ~Fig. 6).
Thus the cam follower surface 140 is not initially disposed in en~agement with the cam sur~ace 188, due to the spring 124 holding the actuating member's lever arm 40 against the stop 143. Moreover, when the cam 180 commences rotation, ; . . :, , -. , : : , : :
:: ,....... : . ,.
.: . . ~ , . . ................................. .
,' ' ': ~ '' ' : ~. . , - -32 - ~32~7 1 the control member's cam follower surface 116 is located out of engagement with the cam's peripherally-extending cam surface 184.

As the cam (Fig. 7 and 7A) continues rotating, the cam's peripherally-extending cam surface 184 slidably engages the control member's cam follower surface 116 and, due to the cam surface 184 spiraling outwardly relative to the axis of the cam drive shaft 182, the control member 100 is gradually rotated clockwise about the pivot shaft 102 against the correspondingly gradually increasing force exerted by the spring 124. Since actuating member 130 ~Fig. 2) is held against the control member 100 by the spring 122, the actuating member 130 rotates in unison with the control member 100 until the actuating member's cam follower surface tFigs. 7 & 7A) contacts the rotating cam surface 188. Whereupon, further movement of the actuating member 130 is stopped, while the control member 100 contin-ues to be rotated by the cam 180. As a result, continued rotation of the control member 100 is accomplished against the gradually increasing forces exerted by both the spring 122 and 124. Moreover, as the control member 100 (Fig. 7B) continues rotation after the actuating member 130 is held by the cam 180, since the latching member's cam follower surface 164 is disposed in sliding engagement with the control member's cam surface 110, the latching member 154 is gradually rotated about the pivot shaft 152 (Fig. 3) against the force exerted by the leaf spring leg 156, until the control member's latching surface 112 is rotated beyond the latching member's latching surface 166. Whereupon the leaf spring leg 156 rotates the latching member's latching surface 166 into facing relationship with the control member's latching surface 112.

Thereafter, as the cam 180 (Fig. 8) still further continues rotation, the cam's peripherally-extending cam surface 18~ disengayes the control member's cam follower surface 116. As a result, the control member's spring 124 urges the control member's latching surface 112 into .
,: ~, ' ~ ' . , -. . .
' :," . ' : ~
'''''' '. '- ~ ' '' " ' .: '; ,: `

~032~71 l~tching engagement with the latching member's latching surface 166, thereby holding the latching member 154 (Fig.

3) against any further rotation until the solenoid 88 (Fig.
2) is re-energized. When the control member 100 (Figs. 8A
and 8B) is thus initially latched in place, the cam 180 has not yet rotated sufficiently to disengage the cam sur~ace 188 from the actuator member's cam follower surface 140.
Accordinyly, the rotating cam 180 continues to maintain the shutter bar's key portion 34 (Fig. 1) out of the drum drive gear slot 30, and continues to maintain the actuating member's key leg 134 (Figs. 8A and 8B) out of cam slot 190, until the cam 180 rotates still further and disengages the cam follower surface 140. Whereupon, the spring 122 rotates the actuating member 130 (Figs. 5, 5A and 5B) into engagement with the latched control member 100, thereby urging the shutter bar's key portion 24 (Fig. 1) into the drum drive gear slot 30 to prevent further rotation of the drum drive gear 26 and thus the drum 24, moving the actuat-ing mem~er's key leg 134 (Figs. 5, 5A and 5B) into the cam slot 190 and concurrently urging the actuating me~ber's shoulder 144 out of engagement with the motor switch 90 for actuating the switch 90. When the switch 90 is actuated, the switch leads 236 and 236B are electrically disconnected for deenergizing the d.c. motor 240, followed by the switch leads 236 and 236A being electrically connected to close the shunt circuit across the d.c. motor 240 for dynamically braking the d.c. motor 240. As a result, the d.c. motor 240 is both deenergized and dynamically braked as the shutter bar key portion 24 (Fig. 1) enters the drum drive gear slot 30 and the actuating member's key leg 134 (Figs.
5, 5A and 5B) enters the cam's slot 190. And, when the spring 122 has rotated the actuating member 130 into engagement with the latched control member 100, the shutter bar key portion 24 tFig. 1) locks the drum drive gear and thus the drum ~4 in their respective home positions, and the actuating member's key leg 134 (Figs. 5, 5A and 5B) locks the cam 1$0 in its home position, thereby returning the drive system 70 (Fig. 2) to its normal or at-ready mode of operation.

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~ 3~ ~ 20~71 In accordance with the objects of the invention there has been described motor speed control circuit for a d.c.
motor connected to a load and, more particularly a circuit for controlling the speed of a d.c. motor independently of variations in the supply voltag~e therefor and independently of variations in motor loading. Although the invention disclosed herein has been described with reference to a simple embodiment thereof, variations and modifications may be made therein by persons skilled in the art without departing from the spirit and scope of the invention.
~ccordingly, it is intended that the following claims cover the disclosed invention and such variations and modifications thereof as fall within the true spirit and scope of the invention.

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Claims (20)

What is Claimed is:

1. In a machine including a d.c. power supply having an output voltage, and including a d.c. motor having a load connected thereto for driving thereby, apparatus for controlling the speed of motor independently of variations in the load, the apparatus comprising:

a. the output voltage being a rectified and unfiltered output voltage;

b. a silicon controlled rectifier having an anode and a cathode and a gate;

c. means for providing a reference voltage to the gate of the rectifier; and d. means for connecting the anode and cathode of the rectifier between the power supply and motor for energizing the motor.

2. The apparatus according to Claim 1, wherein the reference voltage includes a zener diode, and the diode including a cathode connected to the gate of the rectifier.

3. The apparatus according to Claim 1 including means for braking the motor, and the braking means including a capacitor.

4. The apparatus according to Claim 1, wherein the load includes a rotary cam.

5. The apparatus according to Claim 1, wherein the load includes a gear.

6. The apparatus according to Claim 1 wherein the reference voltage providing means includes means for changing the reference voltage.

7. The apparatus according to Claim 1, wherein the connecting means includes a switch.

8. The apparatus according to Claim 1, wherein the output voltage is full-wave rectified.

9. The apparatus according to Claim 1 wherein the motor is a small d.c. motor.

10. The apparatus according to Claim 1, wherein the d.c.
motor is a permanent magnet motor.

11. In a mailing machine base including a motor and a load driven thereby, control apparatus comprising:

a. the motor being a small d.c. motor;

b. a source of supply of d.c. power, the power supply providing a rectified and unfiltered output voltage;
c. a silicon controlled rectifier including an anode and a cathode and a gate, d. means for providing a reference voltage to the gate of the rectifier; and e. means for connecting the anode and cathode of the rectifier between the power supply and motor for energizing the motor.

12. The apparatus according to Claim 11, wherein the connecting means includes a switch.

13. The apparatus according to Claim 11, wherein the load includes a cam, the control apparatus including means for locking and unlocking the cam, and means for operating the locking and unlocking means.

14. The apparatus according to Claim 11, wherein the motor is a permanent magnet motor.

15. The apparatus according to Claim 11 including means for braking the motor.

16. The apparatus according Claim 15, wherein the connecting means includes a switch, the switch including a first position wherein the anode and cathode are connected between the power supply and motor, and the switch including a second position wherein the braking means is connected to the motor.

17. The apparatus according to Claim 15, wherein the braking means includes a zener diode and a capacitor connected across the zener diode.

18. The apparatus according to Claim 11, wherein the power supply includes a positive terminal and a common terminal, the connecting means including means for connecting the anode to the positive terminal of the supply, the motor having a first terminal, and the connecting means including means for connecting the cathode of the rectifier to the first terminal of the motor.

19. The apparatus according to Claim 11, wherein the reference voltage providing means includes means for changing the reference voltage.

20. The apparatus according to Claim 11, wherein the load includes a gear, the control apparatus including means for locking and unlocking the gear, the control apparatus including means for operating the locking and unlocking means.