US3715021A

US3715021A - Variable drive apparatus

Info

Publication number: US3715021A
Application number: US00093339A
Authority: US
Inventors: G Caspari
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1970-11-27
Filing date: 1970-11-27
Publication date: 1973-02-06
Anticipated expiration: 1990-02-06
Also published as: FR2115819A5; CH538937A; DE2157836A1; JPS545652B1; DE2157836C2; CA960986A; GB1330460A; IT940593B

Abstract

Apparatus for imparting various rotational motions to a driven member in which a constantly rotating driving member transmits a predetermined angular velocity to the driven member by means of a frictional coupling. The angular velocity of the driven member is varied by overcoming the driving torque applied to the driven member by the frictional coupling. Means cooperating with the driving and driven members serve, respectively, to brake and to reverse the rotational motion of the driven member.

Description

United States Patent 1191 C aspari 1 VARIABLE DRIVE APPARATUS [75] Inventor:

[73] Assignee: Burroughs Mich.

22 Filed: Nov. 27, 1970 21 App1.No.:93,339

Georg K. Caspari, Plymouth, Mich.

Corporation, Detroit,

52 U.S.Cl ..197/82,197/16,l97/84R, 197/90, 197/176 51 Int.Cl. ..B4lj 19/00 [58]- Field of Search ..197/16, 19, 20, 82, 84, 84 A, 197/84 B, 90, 89, 176, 177, 178, 179

[56] References Cited UNITED STATES PATENTS 3,313,389 4/1967 Cralle ..197/16 X 3,578,129 5/1971 Katu ...197/187 X 3,315,776 4/1967 Barkdoll et a1. 197/82 X 3,554,347 1/1971 Perkins ..197/87 UX 1 Feb. 6, 1973 3,313,387 4/1967 Lenney ..197/84 X 3,225,886 12/1965 Cetran et a1 ..197/84 2,704,591 3/1955 Bogert 197/90 X 2,886,160 5/1959 Frey ..197/84 Primary Examiner--Robert E. Pulfrey Assistant ExaminerR. T. Rader Att0rneyl(enneth L. Miller and Edwin W. Uren [57] ABSTRACT Apparatus for imparting various rotational motions to a driven member in which a constantly rotating driving member transmits a predetermined angular velocity to the driven member by means of a frictional coupling. The angular velocity of the driven member is varied by overcoming the driving torque applied to the driven member by the frictional coupling. Means cooperating with the driving and driven members serve, respectively, to brake and to reverse the rotational motion of the driven member.

11 Claims, 4 Drawing Figures PATENTEDFEB s 1975 SHEET 2 OF 2 VARIABLE DRIVE APPARATUS BACKGROUND OF THE INVENTION This invention relates generally to apparatus for imparting variable rotational motions to a driven member and, more particularly, to apparatus for controllably translating a print carrier along a print line in a printing machine.

In a single element type printing machine, such as an impacting -ball printer, it is required that the print elementor ball be translated along a print line adjacent to a platen for printing characters in a desired format upon a medium interposed between the print element and the platen. A common means for so displacing a print element is by engaging it with a rotatable screw so that the speed and direction of rotation of the screw varies the speed and direction of linear translation of the print element. The control of the rotational motion of the screw is a task requiring a high degree of precision, for the spacing of printed characters, margins, and all other spacing variables in a printing format are dependent upon precise translation of the print element. In a situation where the printing element prints several successive characters on-the-fly the element must be moved at a speed synchronized with the electronically established print rate and character decoding process. In other types of printers where the print element is escaped, accurate control of the stops and starts of the print element must be maintained. In orderto move along the print line for a relatively long distance without printing a character, the print element must be moved as rapidly as feasible to cut the time that printing is held in abeyance. Also the print element must be capable of back spacing, as well as returning from a tabulated position over a long distance at a high rate of speed to a starting print position. Further complicating the requirements of a lead screw rotating apparatus, are considerations of print element acceleration and deceleration which must be given attention to avoid undue strain on the printing apparatus as well as for purposes of synchronizing the print element position with a desired printing operation.

SUMMARY OF THE INVENTION Accordingly, it is a primary aim of this invention to carry out'all of the aforementioned requirements of a print element positioning apparatus in an inexpensive, reliable and efficient manner.

More particularly, it is an object of the present invention to accomplish all of the aforementioned functions in conjunction with one single-speed driving means.

It is a correlated object of the invention to utilize the same driving means for the print element positioning apparatusas is used by the printing machine for print decoding, such that carrier travel is always synchronized with the decoding process.

It is further an object of the invention to effect a change in print element translation velocity by the engagement of a single clutch.

It is still another object of the invention to achieve uniform acceleration of the printing element in escapement and rapid two-stage acceleration in tabulation and return.

A further object of the invention is to decelerate a tabulating or returning print element in two stages in order to avoid excessive stress on the system, while at the same time facilitating high speed movement of the print element.

In accordance with the invention, an electronic printing machine is provided with a print decoder and a timing unit which mechanically positions the print element of the machine. The mechanical energy for carrying out this function is derived from a constant speed driving means. A driving member of a variable drive apparatus is coupled to the driving means for synchronous rotation therewith. For imparting various rotational motions to a driven member that in turn moves a print element carrier, the driving member is coupled to the driven member by a variable coupling means. This means is responsive to electronic carrier control signals for imparting predetermined rotational motions to the driven member. All movements of the driven member, and consequently of the print element carrier, are maintained in constant synchronization with the decoding process.

Another important aspect of the invention is the manner in which the variable coupling means transforms the constant rotation of the drivingmember into the many different motions required by the printing format. In particular, two rotational speeds of the driven member are attained by coupling an input side of a clutch to the driving member, thus driving the input member at a predetermined second angular velocity. The driven member is coupled to the driving member by means of a friction coupling which imparts a predetermined first angular velocity to the driven member. The clutch is connected to the driven member such that engagement of the clutch overcomes the driving torque of the friction coupling and changesthe rotational speed of the driven member to the second predetermined angular velocity.

BRIEF DESCRIPTION OF THE DRAWINGS timing relationships of the several component parts of the variable drive apparatus.

DETAILED DESCRIPTION OF THE DRAWINGS Turning now to the drawings herein like reference characters designate identical elements in each of the four figures, and particularly to FIG. 1, there is shown in schematic form the preferred carrier control apparatus incorporated in an electronic printingmachine'. In such a printing machine a print element carrier 10 is translatable along a predetermined print line by means of a lead screw 12 to which the carrier is engaged by any suitable means. The characters that are to be printed and the order of their printing is stored in an associated memory of a central processor 14 which transmits such information in electronically coded form to a print decoder and timing unit 16. In order to correctly position the print element 18 of the carrier and to actuate a printing impact of the element, the print decoder and timing unit 16 decodes the electronic information transmitted to it by the central processor 14 and communicates the decoded information via a mechanical linkage to the carrier. The power for driving the mechanical linkage of the carrier 10 is provided by a constant speed motor 20 coupled to the print decoder and timing unit 16 by a driving member or shaft 22.

The translation of the carrier 10 along the print line is controlled by the rotation of the lead screw 12 that is in turn driven by variable drive apparatus 24 coupling the driving member 22 with the screw 12. In order to effect the required variation in angular velocity of the lead screw 12, the variable drive apparatus 24 in response to electronic signals from the carrier drive control logic 30, translates the unidirectional constant velocity of the driving member or shaft 22 to a bidirectional, multi-velocity output. The variable drive apparatus 24 also serves to brake the rotation of the lead screw 12 for varying periods of time to achieve an escapement or backspace motion of the carrier 10.

The carrier drive control logic maintains a record of the position of the carrier 10 with the assistance of a position readout device 32 coupled to the lead screw 12. The next desired carrier position is communicated to the carrier drive control logic 30 from the central processor 14 and compared with the present carrier position. When the carrier 10 is located a predetermined distance from the desired position, the control logic 30 is programmed to generate certain electrical control signals to the variable drive apparatus 24 to correctly position the carrier by rotating the lead screw 12. Carrier drive control logic of the variety required is disclosed in a U.S. Pat. No. 3,403,386 entitled Format Control issued to Perkins et al and having common ownership herewith.

In FIG. 2 is illustrated the preferred embodiment of the variable drive apparatus 24. As was described in connection with FIG. 1, a driving member or shaft 22 is rotatable by a motor at a substantially constant angular velocity about a longitudinal axis through the center of the shaft. The rotating driving shaft 22, as stated, is also coupled to the print decoder and timing unit 16 (FIG. 1), so that the rotational motion imparted to the lead screw 12 is always synchronized with the decoding and timing operation of the printing machine. It is from this synchronized driving shaft 22 that all carrier motion is ultimately derived. Variable coupling means, as hereinafter described, serves to vary the driving effect of the driving shaft 22 upon the lead screw 12.

For driving a driven member or shaft 26 at a first or slow angular velocity, an annular geared rim 34 of a friction coupling 36 is engaged by means of a pinion 38 and idler gear 40 to the driving shaft 22. The pinion gear 38 is firmly attached to rotate with the driving shaft 22 and the idler gear 40 is independently supported to rotate in engagement with both the pinion gear and the geared rim 34 of the friction coupling 36. Rotation of the driving member 22 thus rotates the geared rim 34 of the friction coupling 36 in a common direction therewith and at a predetermined velocity.

An inner disk 42 of the friction coupling 36 has an outer periphery positioned in slidable abutment with an inner periphery of the annular geared rim 34 so that rotation of the geared rim frictionally engages the inner disk, thereby tending to rotate the disk with a torque determined by the frictional force between the abutting peripheries of the inner disk and the geared rim. Accordingly, the inner disk 42 may rotate independently of the geared rim 34 if enough torque is applied to the disk to overcome the frictional force between it and the geared rim. To permit the driven shaft 26 to rotate in one direction substantially independently of the friction coupling 36, the inner disk 42 is coupled to the driven shaft by a one-way slip coupling, such as the overrunning spring clutch 44 illustrated in FIG. 3 (but blocked from view in FIG. 2). The spring clutch 44 is configured in the form ofa spiral spring having one end portion 46 wrapped about a sleeve 48 extending from the inner disk 42 of the friction coupling 36, and the other end portion 50 wrapped about an enlarged section 52 of the driven shaft 26. The sleeve 48 of the disk 42 is loosely mounted on the driven shaft 26 to rotate independently thereof. Upon counterclockwise rotation of the friction coupling 36, as shown in FIG. 3, the sleeve 48 of the inner disk 42 is engaged by the spring clutch 44 to carry with it the driven shaft 26 in an effectively rigid fashion whereas a counterclockwise torque on the driven shaft 26 tending to rotate it ahead of the friction coupling tends to disengage the spring clutch from the sleeve of the inner disk. The action of the spring clutch 44 operates to permit the angular velocity of the driven shaft 26 to be increased without having to overcome the relatively high torsional resistance of the friction coupling 36.

The driven member 26 is rotated at an increased angular velocity by an electromagnetic clutch 54 having an input member 56 coupled by a belt and pulley arrangement 58 to the driving shaft 22. The size of the respective pulleys determines the rate of angular velocity for the input member 56 of the electromagnetic clutch 54, that rate being greater than that of the friction coupling 36. Thus, when the electromagnetic clutch 54 engages in response to an electrical signal from the carrier drive control logic 30 (FIG. 1), an output member (not shown) of the clutch 54 connected to the driven shaft 26 transmits the increased or second predetermined angular velocity to the driven member 26 by overcoming the driving influence of the frictional coupling 36, as heretofore described.

The driven member 26 is further connected to a rotation reversal means that is comprised of two similar electromagnetic clutches respectively termed the reverse clutch 60 and the forward clutch 62. An input member (not shown) of the forward clutch is attached to the driven shaft 26 to rotate in the same direction therewith. A geared rim 64 of the input member of the forward clutch 62 engages a similar geared rim 66 of an input member of the reverse clutch 60 for imparting an opposite rotation thereto. Both of these clutches 60-62 are coupled by means of a common belt 68 to a pulley 70 on the lead screw 12 so that the lead screw may be rotated in a forward or reverse direction depending upon which of the two clutches are engaged.

The portion of the apparatus thus far described serves to control the rotational motion of the driven member in two ways: rate and direction. There is another function however, that remains to be implemented in order to precisely control the translation of the carrier along the print line. That is, the carrier 10 must be stopped and started in precise locations and at precise times. The preferred braking means is described in detail i Burroughs Series L Field Engineering Technical Manual, section 2, pages l18-l 19 in connection with Burroughs Models 12000, L3000 and L4000 accounting computers. Briefly, the braking means operates to stop the rotation of the lead screw 12 by engaging a tooth 72 ofa detent wheel 74 with bidirectional latches 7676, the detent wheel being attached to the lead screw for rotation therewith. The bidirectional latches 7676 are biased into engagement with individual teeth 72 of the the detent wheel 74. There are two ways in which the latches 7676 may be disengaged from the wheel 74, one resulting in intermittent disengagement and the other in continuous disengagement. The former is accomplished by actuating an interposing solenoid 78 which effectively engages the braking system with an eccentric cam 80 on the driving shaft 22. The resulting camming action cyclically operates through a mechanical linkage 82 to pull the latches 76--76 away from the detent wheel at constant predetermined intervals. Continuous disengagement is accomplished by actuating a pair of hold solenoids 84-84 which magnetically pivot the latches 7676 away from the detent wheel 74 whenever the solenoidsare actuated. The actuation of the hold solenoid 84 84 allows the lead screw 12 long periods of rotation for tabulation and return operations while the interposer solenoid 78 is actuated to initiate escapement or backspacing movement. A more comprehensive explanation of the operation of the braking means in relation to carrier movement will hereinafter be undertaken.

OPERATION In connection with the timing diagrams of FIG. 4, a preferred timing relationship of the various elements of the variable drive apparatus 26 may be illustrated. A chain of timing pulses is generated by the print decoder and timing unit 16 in synchronization with the driving shaft 22 (FIG. 1). These pulses are used as a timing basis by the carrier drive control logic in determining and generating the other signals for initiating the various functions of the variable drive apparatus 24.

To initiate an escapement operation, a forward clutch engagement signal is generated by the carrier drive control logic 30 at the leading edge of a timing pulse 86. Coincident with the initiation of the forward clutch engagement signal the interposer solenoid 78 is activated by anothersignal from the carrier control logic 30. After the forward clutch 62 is engaged, there is a slight hesitation before the eccentric cam 80 pulls bidirectional latches 76-76 out of engagement with the detent wheel 74 in the manner heretofore described. During this slight hesitation the friction coupling 36 begins to slip, thereby applying a predetermined torsional load to the lead screw 12 so that disengagement of the latches 7676 effects a substantially uniform acceleration 88 until it reaches the first angular velocity 90 determined by the non-slip angular velocity of the driven member 26. As the eccentric cam 80 rotates with the driving member 22, the bidirectional latches 76-76 periodically engage each succeeding tooth 72 of the detent wheel 74 for a short period 92 in which a print command from the print decoder and timing unit 16 activates an impact of the print element 18 of the carrier 10 to print a character. Escapement continues cyclically with the forward clutch 62 remaining engaged until after the last escapement cycle. Each time the bidirectional latches 7676 engage the detent wheel 74, the inner disk 42 of the friction coupling 36 is. halted and the outer rim 34 remains driven, consequently prestressing theleadscrew 12 with a predetermined torsional load that is used to accelerate the lead screw to a predetermined angular velocity when the bidirectional latches are cammed out of engagement with the detent wheel. A back space is accomplished in the same manner as an escapement, the only difference being that instead of engaging the forward clutch 62, the reverse clutch is engaged to rotate the lead screw 12 in the opposite direction.

For tabulation of the print carrier 10 it is desirable that the carrier be moved at an accelerated velocity in order to minimize lapses in the printing operation. A tabulation process is begun in the same manner as an escapement, with the interposer solenoid 78 and the forward clutch 62 activated simultaneously as at 94 in FIG. 4. After the interposer solenoid 78 has removed the bidirectional latches 7676 from engagement with the detent wheel 74, the hold solenoids 84-84 are activated to hold the bidirectional latches out of engagement with the detent wheel. The hold solenoids 84-84 are not used to initially disengage the bidirectional latches 7676 in the preferred configuration, because the force of the camming action initiated by the activation of the interposer solenoid 78 is more precise in time and of greater magnitude than the force that is applied by the hold solenoids 84-84. Such camming action provides a faster and more positive start of lead screw rotation and carrier motion. As the carrier 10 starts to accelerate, as at 96, under the influence of the friction coupling 36, the high speed clutch 54 is engaged to increase the angular velocity of the driven member 26 to the predetermined second velocity thereof as heretofore described. The carrier velocity 98 is thus determined by the angular velocity imparted to the driven shaft 26 by the high speed clutch 54. The carrier continues to tabulate until some predetermined distance before a desired stopping point is reached. At such time the high speed clutch 54 is disengaged, as at 100 in FIG. 4. inherent drag in the system, including the resistance of the residual torque of the slipping spring clutch 44 against the rotating driven shaft 26, serves to decelerate the lead screw 12 to the first or slow angular velocity imparted to the screw by the friction coupling 36. At a second predetermined distance of carrier travel after deceleration, the hold solenoid 84 is deactuated, as at 102, and the bidirectional latches 7676 thereafter reengage the detent wheel 74 to brake the rotation of thelead screw 12, the rim 34 of the friction coupling thereafter continuing to rotate independently of the disk 42.

With a slight modification, the variable drive apparatus could be adapted for on-the-fly printing, in which the carrier would be continuously moved during a printing operation rather than escaping as described above. Such carrier movement may be effected in a similar manner as tabulation, except the high speed clutch 54 would not be engaged. Rather, the rotational speed of the geared rim 34 of the friction coupling 36 would be adjusted by the relative sizes of the pinion 38 and idler 40, to achieve a proper rate of angular velocity for on-the-fly carrier translation. In such an application the angular velocity of the lead screw 12 would always be synchronized with the timing of the print decoder and timing unit 16, consequently the critical problem of synchronizing print rate and print element positioning with carrier translation is greatly simplified.

While the invention has been described in conjunction with a specific embodiment it is evident that many modifications and alternatives not truely departing from the inventive concept residing therein will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace within the scope of the appended claims all such modifications and alternatives that reside with the inventive concept herein disclosed.

What is claimed is:

1. In a printing machine having a print decoder and timing unit for decoding electrical signals representing a character to be printed by a printing element, said unit being mechanically driven by a constant speed driving means and effective to generate an electrical timing pulse in synchronization with said driving means, and having also carrier drive control logic responsive to said timing pulse for generating electronic carrier control signals and variable drive apparatus for translating a carrier of said printing element along a print line, said apparatus comprising,

a rotatable driving member coupled with said driving means for synchronous rotation therewith, a rotatable driven member drivably associated with said driving member, a rotatable carrier driver coupled to said driven member, and variable coupling means drivably coupling said driving member with said driven member,

said variable coupling means said having at least two separate driving connections between said driving member and said driven member for rotatively driving the driven member in the same direction but at different angular velocities thereby to translate said printing element carrier in one direction along the print line but at different speeds for letter spacing and tabulation,

a rotation reversal connection between said driving member and said driven member for reversing the rotation of said carrier driver thereby to translate said printing element carrier in the opposite direction along the print line,

brake means for stopping the rotation of said carrier driver thereby to halt translational movement of said print element carrier, and

means for rendering each of said driving and reversal connections and said brake means responsive to individual ones of said electronic carrier control signals, whereby the stopping, starting, speed and direction of motion of the printing element carrier along the print line is controlled in synchronization with said print decoder and timing unit in accordance with a predetermined printing format.

2. In a printing machine having a print decoder and timing unit for decoding electrical signals representing a character to be printed by a printing element, said decoder being mechanically driven by a constant speed driving means and effective to generate an electrical timing pulse in synchronization with said driving means, and having also carrier drive control logic responsive to said timing pulse for generating electronic carrier control signals, variable drive apparatus for translating a carrier of said printing element along a print line, said apparatus comprising,

a driving member coupled with said driving means for synchronous rotation therewith, a driven member drivably associated with said driving member, a carrier driver coupled to said driven member, and variable coupling means drivably coupling said driving member with said driven member, said variable coupling means being operative to vary the driving effect of said driving member upon said driven member and said carrier driver in response to said electronic carrier control signals, said carrier thus being translated at a variable velocity along the print line in synchronization with said print decoder and timing unit in accordance with a predetermined printing format,

said variable coupling means comprising,

a friction coupling frictionally engaged with said driven member for transmitting a first predetermined torque thereto,

a first means drivably coupling said driving member with said friction coupling for driving said driven member in a first direction at a first predetermined angular velocity,

an engageable clutch having an output member fixedly attached to said driven member for rotation therewith and an input member controllably engageable into driving relationship with said output member in response to a first electrical signal for transmitting a second predetermined driving torque to said driven member,

second coupling means drivably coupling said input member of each engageable clutch with said driving member for rotation of said input member in said first direction at a second predetermined angular velocity, said second predetermined angular velocity being greater than said first predetermined angular velocity,

rotation reversal means coupled to said driven member and responsive to a second electrical signal for reversing the direction of rotation of said carrier driver, and

braking means coupled to said carrier driver and responsive to said driving means and to a third electrical signal for braking the rotational motion of said carrier driver and said driven member, whereby the stopping, starting, speed and direction of angular motion of said carrier driver is controllable by corresponding ones of said electrical signals.

3. in printing apparatus having means for varying the angular velocity of a driven member, said means comprising,

a driving member,

means for rotating said driving member at a constant angular velocity,

a friction coupling frictionally engaged with said driven member for transmitting a first predetermined driving torque thereto,

first means drivably coupling said driving member with said friction coupling for driving said driven member at a first predetermined angular velocity,

an engageable electromagnetic clutch having an output member fixedly attached to said driven member for rotation therewith and further having an input member controllably engageable into driving relationship with said output member for transmitting a second predetermined driving torque to the driven member, and

second means drivably coupling the said input member with said driving member for rotating said input member at a second predetermined angular velocity in the same direction as applied by said first coupling means but at a greater velocity than said first predetermined angular velocity, whereby the engagement of said engageable clutch overcomes the first predetermined driving torque of said friction clutch to rotate said driven member at said second predetermined angular velocity.

4. Apparatus as defined by claim 3 wherein said friction coupling is comprised of an annular disk having a geared annular rim engaged with said first coupling means, said rim having an inner periphery frictionally engaged with the periphery of an inner disk, said inner disk being drivably coupled to said driven member.

5. Apparatus as defined by claim 4 further including a one-way slip clutch for coupling the inner disk of said friction coupling with said driven member, said oneway slip clutch being rigidly engaged with said driving member for transmitting said first driving torque thereto, but effective to disengage said friction coupling from said driving member under the influence of said second driving torque transmitted to said driven member by said engageable clutch.

6. A mechanism as defined by claim 5 wherein said one-way slip coupling is a spring clutch having one end portion coupled to said friction coupling and another end portion coupled to said driving member.

7. in printing apparatus, print carrier positioning mechanism including means for varying the angular motion of a print carrier driver in response to corresponding electrical signals, said means comprising,

a driven member operatively coupled to said print carrier driver,

a driving member,

means for rotating said driving member at a constant angular velocity,

second coupling means drivably coupling said input member with said driving member for rotation of said input member in said first direction at a second predetermined angular velocity, said second predetermined angular velocity being greater than said first predetermined angular velocity,

rotation reversal means coupled to said driven member and responsive to a second electrical signal for reversing the direction of rotation of said print carrier driver, and

braking means coupled to said print carrier driver and responsive to said driving means and to a third electrical signal for braking the rotational motion of said carrier driver and said driven member whereby the stopping, starting, speed and direction of angular motion of said print carrier driver is controllable by corresponding ones of said signals.

8. Apparatus as defined in claim 7 further comprising a one-way slip clutch for drivably engaging said friction coupling with said driven member at said first predetermined angular velocity, said one-way slip clutch being operative to disengage from said friction coupling when said driven member is accelerated by said engageable clutch, said one-way slip clutch remaining disengaged until said driven member decelerat'es to an angular velocity equal to said first predetermined angular velocity.

9. Apparatus as defined in claim 8 wherein said oneway slip clutch is a spring clutch having one end portion coupled to said friction coupling and another end portion coupled to said driven member.

10. In printing apparatus, print carrier positioning mechanism including means for varying the angular motion and direction of a print carrier driver in response to corresponding electrical signals, said means comprising,

a driven member operatively coupled to said print carrier driver,

a driving member normally rotatable at a constant velocity,

a first coupling means drivingly coupling said driving member with said driven member for driving the latter in a first direction at a first angular velocity,

a second coupling means for disengagingly coupling said driving member with said driven member and operable when coupled thereto to drive the latter in the same direction as said first coupling means but at a different angular velocity, said second coupling means being responsive to a first electrical signal for performing its aforesaid coupling function,

rotation reversal means disengagingly coupling said driven member with said print carrier driver'and responsive to a second electrical signal for reversing the direction of rotation of said print carrier driver, and i braking means coupled to said print carrier driver and responsive to said driving means and to a third electrical signal for braking the rotational motion of said carrier driver and said driven member whereby the stopping, starting, speed and direction of angular motion of said print carrier driver is controllable by corresponding ones of said signals.

33 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3,7 5, 4 Bas d Feb. 6, 1973 Invenfm-(s) Georg Karl Caspari It is certified that error appears in the above-ideantiffned patent and that said Letters Patent are hereby corrected as shown below:

Col. 7, line 32, after "and" insert --the printing machineline 3 after "and" insert --further having- Col. 8,line I, delete "decoder" and substitute therefore --unj line 7, after "and" insert --the machine-; line 9, after the comma insert --and having-.

Signed and sealed this 3rd day of July i973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Rene Tegtmeyer I I I Attesting Officer Actin Commissioner -of Patents

Claims

1. In a printing machine having a print decoder and timing unit for decoding electrical signals representing a character to be printed by a printing element, said unit being mechanically driven by a constant speed driving means and effective to generate an electrical timing pulse in synchronization with said driving means, and having also carrier drive control logic responsive to said timing pulse for generating electronic carrier control signals and variable drive apparatus for translating a carrier of said printing element along a print line, said apparatus comprising, a rotatable driving member coupled with said driving means for synchronous rotation therewith, a rotatable driven member drivably associated with said driving member, a rotatable carrier driver coupled to said driven member, and variable coupling means drivably coupling said driving member with said driven member, said variable coupling means said having at least two separate driving connections between said driving member and said driven member for rotatively driving the driven member in the same direction but at different angular velocities thereby to translate said printing element carrier in one direction along the print line but at different speeds for letter spacing and tabulation, a rotation reversal connection between said driving member and said driven member for reversing the rotation of said carrier driver thereby to translate said printing element carrieR in the opposite direction along the print line, brake means for stopping the rotation of said carrier driver thereby to halt translational movement of said print element carrier, and means for rendering each of said driving and reversal connections and said brake means responsive to individual ones of said electronic carrier control signals, whereby the stopping, starting, speed and direction of motion of the printing element carrier along the print line is controlled in synchronization with said print decoder and timing unit in accordance with a predetermined printing format.

2. In a printing machine having a print decoder and timing unit for decoding electrical signals representing a character to be printed by a printing element, said decoder being mechanically driven by a constant speed driving means and effective to generate an electrical timing pulse in synchronization with said driving means, and having also carrier drive control logic responsive to said timing pulse for generating electronic carrier control signals, variable drive apparatus for translating a carrier of said printing element along a print line, said apparatus comprising, a driving member coupled with said driving means for synchronous rotation therewith, a driven member drivably associated with said driving member, a carrier driver coupled to said driven member, and variable coupling means drivably coupling said driving member with said driven member, said variable coupling means being operative to vary the driving effect of said driving member upon said driven member and said carrier driver in response to said electronic carrier control signals, said carrier thus being translated at a variable velocity along the print line in synchronization with said print decoder and timing unit in accordance with a predetermined printing format, said variable coupling means comprising, a friction coupling frictionally engaged with said driven member for transmitting a first predetermined torque thereto, a first means drivably coupling said driving member with said friction coupling for driving said driven member in a first direction at a first predetermined angular velocity, an engageable clutch having an output member fixedly attached to said driven member for rotation therewith and an input member controllably engageable into driving relationship with said output member in response to a first electrical signal for transmitting a second predetermined driving torque to said driven member, second coupling means drivably coupling said input member of each engageable clutch with said driving member for rotation of said input member in said first direction at a second predetermined angular velocity, said second predetermined angular velocity being greater than said first predetermined angular velocity, rotation reversal means coupled to said driven member and responsive to a second electrical signal for reversing the direction of rotation of said carrier driver, and braking means coupled to said carrier driver and responsive to said driving means and to a third electrical signal for braking the rotational motion of said carrier driver and said driven member, whereby the stopping, starting, speed and direction of angular motion of said carrier driver is controllable by corresponding ones of said electrical signals.

3. In printing apparatus having means for varying the angular velocity of a driven member, said means comprising, a driving member, means for rotating said driving member at a constant angular velocity, a friction coupling frictionally engaged with said driven member for transmitting a first predetermined driving torque thereto, first means drivably coupling said driving member with said friction coupling for driving said driven member at a first predetermined angular velocity, an engageable electromagnetic clutch having an output member fixedly attached to said driven member for rotation therewith and further having an input mEmber controllably engageable into driving relationship with said output member for transmitting a second predetermined driving torque to the driven member, and second means drivably coupling the said input member with said driving member for rotating said input member at a second predetermined angular velocity in the same direction as applied by said first coupling means but at a greater velocity than said first predetermined angular velocity, whereby the engagement of said engageable clutch overcomes the first predetermined driving torque of said friction clutch to rotate said driven member at said second predetermined angular velocity.

5. Apparatus as defined by claim 4 further including a one-way slip clutch for coupling the inner disk of said friction coupling with said driven member, said one-way slip clutch being rigidly engaged with said driving member for transmitting said first driving torque thereto, but effective to disengage said friction coupling from said driving member under the influence of said second driving torque transmitted to said driven member by said engageable clutch.

7. In printing apparatus, print carrier positioning mechanism including means for varying the angular motion of a print carrier driver in response to corresponding electrical signals, said means comprising, a driven member operatively coupled to said print carrier driver, a driving member, means for rotating said driving member at a constant angular velocity, a friction coupling frictionally engaged with said driven member for transmitting a first predetermined torque thereto, a first means drivably coupling said driving member with said friction coupling for driving said driven member in a first direction at a first predetermined angular velocity, an engageable clutch having an output member fixedly attached to said driven member for rotation therewith and an input member controllably engageable into driving relationship with said output member in response to a first electrical signal for transmitting a second predetermined driving torque to said driven member, second coupling means drivably coupling said input member with said driving member for rotation of said input member in said first direction at a second predetermined angular velocity, said second predetermined angular velocity being greater than said first predetermined angular velocity, rotation reversal means coupled to said driven member and responsive to a second electrical signal for reversing the direction of rotation of said print carrier driver, and braking means coupled to said print carrier driver and responsive to said driving means and to a third electrical signal for braking the rotational motion of said carrier driver and said driven member whereby the stopping, starting, speed and direction of angular motion of said print carrier driver is controllable by corresponding ones of said signals.

8. Apparatus as defined in claim 7 further comprising a one-way slip clutch for drivably engaging said friction coupling with said driven member at said first predetermined angular velocity, said one-way slip clutch being operative to disengage from said friction coupling when said driven member is accelerated by said engageable clutch, said one-way slip clutch remaining disengaged until said driven member decelerates to an angular velocity equal to said first predetermined angular velocity.

9. Apparatus as defined in claim 8 wherein saiD one-way slip clutch is a spring clutch having one end portion coupled to said friction coupling and another end portion coupled to said driven member.

10. In printing apparatus, print carrier positioning mechanism including means for varying the angular motion and direction of a print carrier driver in response to corresponding electrical signals, said means comprising, a driven member operatively coupled to said print carrier driver, a driving member normally rotatable at a constant velocity, a first coupling means drivingly coupling said driving member with said driven member for driving the latter in a first direction at a first angular velocity, a second coupling means for disengagingly coupling said driving member with said driven member and operable when coupled thereto to drive the latter in the same direction as said first coupling means but at a different angular velocity, said second coupling means being responsive to a first electrical signal for performing its aforesaid coupling function, rotation reversal means disengagingly coupling said driven member with said print carrier driver and responsive to a second electrical signal for reversing the direction of rotation of said print carrier driver, and braking means coupled to said print carrier driver and responsive to said driving means and to a third electrical signal for braking the rotational motion of said carrier driver and said driven member whereby the stopping, starting, speed and direction of angular motion of said print carrier driver is controllable by corresponding ones of said signals.