US3085504A

US3085504A - Printing apparatus

Info

Publication number: US3085504A
Application number: US863364A
Authority: US
Inventors: Paige Walter Griffin; Paul R Hoffman
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1959-12-31
Filing date: 1959-12-31
Publication date: 1963-04-16
Anticipated expiration: 1980-04-16

Description

April 16, 1963 Filed Dec. 5l, 1959 W. G. PAIGE ETAL PRINTING APPARATUS 6 Sheets-Sheet 1 1N VEN TORS.

W. GR|FF\N PAIGE PAUL R. HOFFMAN April 16, 1963' w. G. PAlsE ETAL 3,085,504

PRINTING APPARATUS lFiled Dec.i 31, 1959 6 Sheets-"Sheet 2 Fig. 2

lso |76 1N VEN TOR.

W. GRIFFIN PAIGE PAUL R. HOFFMAN AGENT )l BY April 16, 1963 w. G. PAIGE ETAL PRINTING APPARATUS 6 Sheets-Sheet 3 Filed Dec. 3l, 1959 JNVENToRs. w. GRxFFlN PAIGE PAUL R. HOFFMAN 1MM, K. /ll

AGENT April 16, 1963 w. G. PAIGE Em. 3,085,504

PRINTING APPARATUS Filed Dec. 31, 1959 6 Sheets-Sheet 4 JNVENTORS. iq/5 w. GRIFFlN PAlGE BY PAUL R. HOFFMAN AGENT April 16, 1963 w. G. PAIGE ETAL 3,085,504

PRINTING APPARATUS Filed Dec. 31, 1959 6 Sheets-Sheet 5 AGENT April 16, 1963 w. G.PA1GE ETAL PRINTING APPARATUS 6 Sheets-Sheet 6 Filed Dec. 5l, 1959 vom INVENTORS.

W. GRIFFIN PAIGE PAUL. R. HOFFMAN o o BY QS AGENT 08m m www. o

3,085,564 PIIENTENG APPARATUS Waiter Griihn Paige, Paoli, and Paul E. Hoffman, Woodlyn, Fa., assignors to Burroughs Corporation, Detroit, Mich., a corporation of Michigan Filed Bec. 31, 1959, Ser. No. 863,364 1l Claims. (Cl. itil-93) This invention relates to novel printing apparatus and particularly to high speed multiple printing apparatus.

More particularly, this invention relates to printers which print with preformed type and utilize a platen over which a document is passed and the print is impressed from the front. These printers have Several favorable features in that they produce a high quality impression, and the printed `line becomes immediately visible. These machines print on any stock thickness that can be wrapped around a platen, and handle any width of continuous roll paper or single documents of random width.

The speed yof most platen front printing machines is limited by the large masses which carry the type members, by the necessity to stop or slow down the printing elements and return each to its home position, and by the time required to select one of the many characters contained on the element. The high speed of the printing machine of the present invention is due to the shape and mounting of multifaced printing elements and to time sharing in the movement of operating parts of the apparatus for the selection of characters. In front printers of conventional construction each printing element has one character face and can move vertically only in one direction. ln the apparatus of the present invention, each printing element can be reciprocated past the printing line of the platen, and while this movement is occurring it can be rotated about its axis to one of its character bearing faces.

The principal object of this invention -is to provide an improved high speed printing apparatus for effecting multiple printing operations.

Another object of this invention is to provide an improved printing apparatus capable of effecting full line printing at high speeds and with economy in the number and design of the operating parts.

Another object of this invention is to provide in printing apparatus novel shaped printing elements and associated parts which enable the elements to be closely spaced in side by side arrangement relative to a document which is to be printed upon and which further enable these elements to be simultaneously displaced, lineally and rotatably, to present a selected one of a multiplicity of characters on each element for printing.

Another object of the invention is to provide in printing apparatus improved means for imparting both linear and rotatable displacements simultaneously of the printing elements and for controlling the operation thereof.

In carrying out the objects of the invention, a printing mechanism embodying the invention includes a plurality of type elements or bars arranged opposite a print-receiving document. Each type bar includes a plurality of type bearing faces and is mounted for rotation in a carrier which may be moved past the platen of the mechanism. The elevation of the type bar as well as the selection of a given face thereof is determined by signals from electrical control circuits. The selection of one of the faces of each type bar is caused by the movement of a pinion which is twisted through an angle by a pair of racks which engage opposed surfaces of the pinion. With each cycle of machine operation the two racks reciprocate in opposite directions in a manner to cause the axis of the pinion to remain stationary but imparting rotative oscillation to the pinion. The pinion is connected by a torsion wire to the type bar and. in the present embodiment of assetti Patented Apr. 16, 1963 the invention an arresting member (having a like number of -faces as the print bar) is provided which follows the motion ofthe type bar.

A locating electromagnet infront `of each arresting member will, when energized, act thereupon to stop further rotary motion of the type bar while at the same time its driving ytorsion wire absorbs any additional torque applied thereto by the racks. A pawl structure and actuating means therefor, upon signal from the control circuits, will cause the pawl structure to engage the carrier and interrupt its lineal movement to thus present a selected character opposite the platen for printing. Thereafter the print hammer associated with each carrier is released to drive the print bar to the platen, where the character impression is produced on a document overlying the platen.

Various other objects, advantages and meritorious features will become more fully apparent from the following specification, appended claims and accompanying drawings, wherein:

FIG. 1 is a perspective view of a printing apparatus embodying the invention;

FIG. 2 is a vertical sectional View through the apparatus of FIG. 1;

FIG. 3 is a sectional view similar to FIG. 2 but in larger scale showing a different position of the operating parts thereof;

FIG. 4 is a sectional view of the type bar actuating mechanism showing the position of the parts for immobilizing a type bar of the apparatus;

FIG. 5 is a greatly enlarged view of one of the prismatic print bars and associated elements connected thereto for controlling its operation;

FIG. 6 is a composite view showing the three faces of one of the prismatic type bars;

FIG. 7 is an enlarged cross sectional view taken along the line 7-7 of FIG. 5;

FIG. 8 is an enlarged cross sectional view taken along the line 3-8 of FIG. 5;

FIG. 9 is an enlarged cross sectional view of the arresting member taken along the Aline 9--9 of FIG. 5;

FIG. l0 is an enlarged cross sectional View of drive pinion for a print bar taken along the line lll-10 of FIG. 5;

FIG. ll is an enlargedcross sectional view of the print bar taken along the line 1].-11 of FIG. 6';

FIG. 12 is an enlarged cross sectional view taken along line 12--12 of FIG. 5 and illustrating the angular displaced relation of its type bar to its arresting member;

FIG. 13 is an enlarged cross sectional view taken along the line 13-13 of FIG. Z showing the members for arresting rotation of a type bar;

FIG. 14 is a greatly enlarged sectional view taken through line 14-14 of FIG. 2 showing the relation of the hammer mechanism to the type carrier and type bar;

FIG. l5 is an enlarged elevational view partly in section, illustrating the position of the type bar before striking the platen;

FIG. 16 is a view similar to FIG. 15 but showing the type bar in striking engagement with the platen;

FIG. 17 is an enlarged longitudinal sectional view through a portion of the platen illustrating different positions of a plural number of type bars with respect thereto;

FIG. 18 is an enlarged sectional view through a group of adjacent type bars showing their close proximity to one another and different rotative positions assumed thereby;

FIG. 19 is a schematic View illustrating an electrical control circuit for controlling the operation of the apparatus;

FIG. 19a is a view of a portion of a record member utilized for controlling the operation of the apparatus.

The various figures illustrate a preferred embodiment of the invention of which FIG. 1 shows the general organization thereof. The printing mechanism includes certain supporting members which may comprise a base plate 20, a left side plate 22 and a right side plate 24. Bridging the space between the side plates are certain major operating elements of the mechanism including a platen 26 around which a print receiving member or sheet 28 may be partially wound in the manner illustrated in FIG. 1. The opposite ends of the platen may be suitably journalled in the side plates for intermittent rotation for advancing the sheet from line position to line position in a conventional manner. The preferred embodiment of the invention is capable of printing a whole line of characters on the sheet at one time and for this purpose a plurality of multi-faced rotatable type elements or bars 30 are provided, one at each printing station. The number of such printing elements may vary but for printing wide sheets, as many as 120 elements or type bars may be mounted in close side by side relation in the mechanism. Also bridging the space between the side plates are two

shafts

32 and 34, the former serving to control the operation of print hammers 36, one of which is shown in FIG. 1, and the other serving to provide driving cams for controlling the vertical reciprocation of the type elements. As will be described in more detail hereinafter, each type element or bar 30 is rotatably journalled in a carrier or frame 38 and the two together are capable both of vertical reciprocating movement and lateral movement toward and away from the platen. In addition, each type bar has an independent rotative movement about its longitudinal axis relative to its carriers.

Externally of the side plate 22 there is shown in FIG. 1 certain driving elements for operating the movable parts of the mechanism. An endless driving belt 40 which is connected to the source of power, not shown, such as an electric motor, drives sheave wheel 42, which, through pinion 44, drives larger gear wheel 46 fixed on the extremity of the hammer operating shaft 32. An endless belt 48 is driven from a sheave wheel 50 on shaft 32 past the idler 52 to sheave wheel 54, carried by stub shaft 56. The stub shaft is journalled in the side plate 22 and as will be described in more detail hereinafter, carries a cam barrel 58 slotted as at 60 for driving a pair of

reciprocating racks

62 and 64. The two racks extend across the space between the two side plates below and in line with the type elements or bars 30 and serve as will be described hereinafter to rotate these elements to present their different faces to the platen. As will be described in more detail hereinafter, the connection between the cam barrel S8 and the rack bars `62 and 64 is such as to reciprocate these two shafts in time sequence, but in opposite directions to one another, to impart the desired rotary movement to the type elements.

Included in the printing mechanism are certain control devices for selecting the desired character of each type element for printing impression upon the record member or sheet 28. Such devices are electrically operated and controlled from a circuit such as that shown in FIG. 19. In general the control devices are in a form of electro-magnetic instrumentalities. Three banks of such magnetic devices are generally indicated at 66, 68, and 70 which, as shown in FIG. 1, extend across the space between the

side plates

22 and 24 and are supported thereby. 1

Magnetic devices 66 are used to control the vertical movement of the type carriers 38 during the time that the toothed rack members `62 and 64 impart rotational movement to the type bars 30 through a 240 degree angle and return in a manner which will be described in detail hereinafter. When the face of each type bar carrying the selected character which is to be printed is rotated so that it is opposite the platen, the magnetic devices 68 lock and prevent the type bar from rotating further. The final vertical position of the type bar is fixed when magnetic devices 70 thereafter activate pawl structure to engage and arrest the type carrier against further vertical movement. This occurs when the selected character is thus positioned at its proper elevation opposite the platen. Thereafter rotation of the print hammer cam shaft 34 to its drop off position permits the print hammers to be powered by drive springs to strike the back of the type carrier and to thus impact the type bars against the platen.

It may be briefly mentioned at this time that each type bar 30 is mounted for rotation in its carrier 38 and it will be understood that a similar mounting is provided for the remaining type bars in the printer at each character position along the platen. Because of the novel provision for applying rotative movement to all of the type bars from a driving device common to all, and other economies in the operating parts, the size of the printer may be made considerably smaller than line printers heretofore developed. The illustrated embodiment of the invention may be roughly about 12 high and 12 deep, and its width of course will be dependent on the number of print bars employed in the printer.

The print or type bars "30, of which there can be any number, are spaced in the present embodiment on 1/10 centers, lO to the inch. As seen now in FIGS. 2, 5 and 6, each type bar 30 exhibits the form of a narrow equilateral triangular prism which may have upper and lower sets of printing characters formed on the three faces thereof. The three faces of each type bar assume an equilateral triangle and in order to provide extremely close side by side spacing of the type bars, the apexes of these faces may be suitably bevelled as shown in the cross sectional views of FIGS. 7, ll and 18. As best seen in FIGS. 3 and 6, the type bar 30 normally stands in a neutral position such that its mid-point designated by the reference character 31 lies opposite the printing line position of the platen 26. Each type bar is rotatably mounted in the type carrier or frame 38 for rotation about its longitudinal axis and for this purpose includes integral spindle extensions of reduced cross section designated 72 and 74, and an intermediate reduced portion 76 which are mounted in bearing portions 78, 8l) and 82 respectively of the type carrier.

Depending from the lower extremity of each type bar is an elongated torsion member 84 of reduced cross section which serves to transmit torque to the type bar 30. A suitable construction for the torsion member is a narrow cylindrical rod or wire of beryllium copper alloy. Secured to the lower end of torsion wire 84 is an elon gated generally cylindrical member 86 which serves to transmit torque from the previously mentioned

rack members

62 and 64 to the type bar 30 which is xed in a similar manner to the upper end of the torsion wire. 'Ihe elongated cylindrical member 86 is formed with toothed portions or splines 88, such as shown in FIG. l0, which extend lengthwise along the outer periphery of the member are for a distance substantially greater than the height of the rack members which drive the same.

'In order to arrest the rotation imparted to the type bar 30 by the toothed member 86, an arresting sleeve member 90 is shown encircling the intermediate portion of torsion wire 84 and may be xed thereto in any suitable manner, such as by having its upper end tightly crimped or soldered to the wire as shown at 92 in FIG. 5. As shown in FIG. 9, the balance of the arresting member is hollowed interiorly to provide a bore 94 which is slightly larger in diameter than the wire 84 and permits the torsion stresses or twists to occur over a major portion of the wire. The member which is arrested is moreover shown in the present embodiment of thc invention as be ing of the same general external conguration as the type bar and has three at faces, 96, 98 and 10i) which form t an equilateral triangle in cross section as shown in FIG.

9. The faces of the arresting prism 90 are preferably angularly offset 45 with respect to the printing faces of the type bar 30 and this may be seen in greater detail in FIG. l2. Thus, the apex formed by the

faces

96 and 100 is aligned with the center of the printing face 30a of the type bar, while the apex formed by the faces 96 and 9S is similarly aligned with face Sile of the type bar and the remaining apex is thus correspondingly aligned with the remaining face Stirb thereof. The length of torsion wire 84 between the secured upper end 92 of the arresting member 90 and its securement to the lower end of the type bar provides a flexible driving connection which not only transmits torque but is sufficiently flexible to allow the lateral movement oi' the carrier 3S and its type bar toward and away from the platen for printing impact upon the recording member or sheet 23.

As earlier mentioned herein, sleeve 9i) forms part of the mechanism for arresting rotation of the type bar 30 with which it is associated. Mounted adjacent to the side of each sleeve opposite to the carrier 3d, there is provided a detent device controlled for movement into and out of engagement with the sleeve 9h and when so engaged acting to hold the same and the type bar from rotation. A preferred detent device comprises a grooved vwheel 102 shown in FIGS. 3 and 13. The groove of the wheel corresponds to the angularity of the side faces of the sleeve 9d as shown in `FlG. 13 such that when the wheel is moved `into engagement therewith the walls of the groove make surface contact with two adjacent sides ot' the sleeve thus securely holding the sleeve and the type bar from rotative movement. The wheel 132 is freely journalled on a pin 10d mounted across the upper biurcated end of a lever 106. As shown in PEG. 3, the opposite lower end of the lever is pivoted lon a pin 03 secured to the upper edge of a cross bar lid which serves similarly to support the pivot pins and levers of the remaining detent devices of the machine. The lever we is yieldingly urged out of engagement with its respective sleeve 9i? by means of a spring 112 tixed at one end, such as to the lower end of the cross bar Zilli?, and secured at the other end to a small projecting arm M4 forming a lateral extension of the lever in the manner shown in PEG. 3. Under control of signals from the control circuit, the lever 1% is forced toward the sleeve 9i? against the resistance of spring M2 to bring its wheel MZ into locking engagement with the sleeve. For this purpose, there is provided a push rod 116 kfor each lever which, as shown in ilG. 3, is in abutting engagement with the side of the lever opposite the sleeve. The push rod is actuated by one of the electromagnets 11S in the bank of magnetic devices 68. The push rod is coupled to the armature 12% of the electr-omagnet by a suitable collar ft2?. rlxed to the push rod. The opposite end of the armature 1219 may be hinged to a wall member of the bank itl in any suitable manner, and it is apparent upon energization of the magnet H8 it will attract the armature and push the rod 116 in the direction of the lever and cause interlocking engagement of the wheel le?. with the sleeve 9d. When this occurs the selected apex of the arresting sleeve 9) enters the groove of the wheel, and the wheel thus restrains the sleeve and its associated type bar from further rotation, and moreover correctly aligns the selected face ot the type bar so that it is in printing position. The wheel 120, because of its journal mounting on pin ldd, however, permits longitudinal travel tof the arresting sleeve 3) even though it is in locking engagement therewith. This enables the sleeve and associated torsion wire and printing bar to be vertically positioned while it is held from rotation.

With reference to FiGS. l, 2 and 3, each carrier 38 and its type bar .3d mounted therein is guided for vertical reciprocation so that the two sets of type characters on each of the three faces of the prismatic type bar may be presented opposite to the printing platen 2'6. When the machine is at rest, the type bar 30 is in its neutral position so that one set of printing characters on each face lies above the printing line of the platen and the other set of characters on the same face lie below the printing line. The lower portion of each type carrier 38 is slidably received in a slot of a comb member 13th extending across the machine which prevents sidewise movement of the carrier, but at the same time operates to guide the carrier for vertical movement. In a similar manner the comb 13d serves to guide the remaining type carriers of the machine.

Each type carrier 38, in addition, includes two sets of

teeth

132 and 134, along its lower edge portion, the spacing of each tooth corresponding to the vertical distance or displacement between adjacent characters of each set of characters on the faces of the prismatic type bar. Thus, corresponding to each character on the type bar as seen in FiG. 6, there is a corresponding tooth on the type carrier. On each of the three type faces, as seen in FIG. 6, there are shown nine characters above the midpoint 3i and nine characters or symbols below the midpoint, -and in the same manner, the set of teeth 132 includes nine teeth and the set of teeth 134 likewise includes nine demarcations. The two sets of teeth 132 and E34 are preferably longitudinally spaced apart on the carrier and oppositely inclined to one another as shown in IFlGS. 2 and 3. As will be brought out in greater detail later, the medium which controls the operation of the printer determines in which direction the type bar shall travel, that is, up or down.

F or providing the reciprocating movement of each type bar and carrier assembly, there are provided two actuators in the form of levers and i4@ mounted in superposed relation to one another and in straddling relation to the cross shaft 34 previously mentioned. With reference to FIGS. 2 and 3, it is to be noted that the 'two levers are outwardly bent intermediate their respective length to also straddle a cross frame member i142 which has its ends supported in the

side plates

22 and 24 of the machine. The ends of the levers adjacent to the type carrier y38 are tapered to provide relatively pointed extremities, each of which is receivable in a notch located on the rear side of the type carrier. The pointed end 144 of the upper lever is receivable in notch 146 of the carrier; and the pointed end 148 of the lower level 144 is receivable in the notch 150 of the carrier. The opposite or rear ends of the levers are pivotally connected to the arms of a bell crank lever 152 which yis .pivoted at its midportion to a frame member 154 extending across the machine from one side wall to the other. The rear end of the upper lever is connected by pin 156 to the upper arm of the bell crank lever and similarly the rear end of the lower lever is connected by pin 15S to the lower arm of the bell crank lever. In FlG. 2, the two levers are shown in full line in the normal or at rest position of the machine. The two levers, however, are capable of movement outwardly away from one another from their full line positions shown in FlG. 2 to the dotted line positions illustrated in that figure. It is to be noted that in the normal or at rest position of the levers that the pointed end M8 of the lower lever is in engagement with its respective notch 150 whereas the pointed end 146 of the upper lever is free or clear of its respective notch "1416. it is apparent that if in this position a slightly counterclockwise movement is imparted to the bell crank lever 152 it will project the pointed end of the lever 138- into its notch in the carrier while at the same time withdrawing the pointed end of the lower lever 1li-0 from its respective notch in the carrier.

For the printing of each line of characters, the two

levers

138 and 146 are urged outwardly away from one another and if one or the other is engaged with its respective notch in the carrier it will cause the carrier to partake of this same movement. To provide the opening and return movements of the two levers, there are provided a pair of transversely extending hails 160* and 162, the former bail being located above the upper lever 138 in approximate alignment with the shaft 34 and the latter bail being located below the lower lever 140 likewise in approximate alignment with the shaft and the other bail. Each bail may be similarly formed out of a narrow strip of metal and extends across machine and has its opposite ends mounted for swingable movement about an axis toward and away from the shaft 34. As shown in FIG. 2, the lower edge of the upper bail 160 is inturned upon itself in the form of a U-shape to serve as an abutment 164 for engaging the upper tier of levers `1318. The opposite edge of the upper bail is outwardly turned to form a ange 166. A spring 168 is connected to each upper lever 138 at one end and to the tlange 166 of the bail at the other end. The lower bail 162 is similarly formed as the upper bail having an abutment 170 for engagement by the lower tier of levers 140 and a flange 172 between which and each lower lever a spring 174 extends. Each

spring

168 or 174 yieldingly urges its respective lever against the abutment of its bail and tends to cause the lever to follow the movement of the bail.

Each bail, as previously mentioned, is swingable about an axis toward and away from the shaft 34. For this purpose the opposite end of the upper bail is secured to arms or segments 176 located externally of the two side plates, one associated with each side plate. The lower bail 162 is similarly secured to arms 178 externally of the side walls. To provide clearance for the movement of the bails between their innermost and outermost positions, the side walls of the machine are provided with cutouts. For the upper bail 160, each side plate is provided with an outwardly opening cutout 180 extending slightly short of the shaft 34. For the lower bail 162 each side wall is provided with similarly shaped aligned opening 182, suicient clearance being provided by the opening to allow swinging movement of the bail about its axis.

During the operation of the machine the two

bails

160 and 162 are caused to be simultaneously moved away from the shaft and returned during each line printing cycle. This is accomplished in the illustrated embodiment of the invention by the provision of rollers, and a cam carried on each extremity of the rotating shaft 34. One cam is shown at 184 which, as shown in FIG. 1, is mounted on the shaft 34 externally of the left side plate 22 partially under the larger gear wheel 46. The shape of the cam is illustrated by the dotted outline thereof appearing in FIGS. 2, 3 and by a full line thereof in FIG. 4. A similar cam is mounted on the opposite extremity of the shaft 34 externally of the right side plate 24. As probably best shown in FIG. 4, each cam is double lobed, that is, it is provided with t-wo rises approximately 180 degrees apart from one another. Riding on each cam are a pair of rollers for guiding the bails. The roller for the upper bail is indicated at 1186 and is journalled to a pin axed to the outer side of the ann 176. The roller for the lower bail 162 is indicated at 188 and is similarly mounted with respect to arm 178. It is evident that upon continuous rotation of the two cams 184 in the same direction that the rollers will r-ide thereon and cause their respective bails to oscillate about their respective pivotal mountings on the side plates. As this movement occurs the two

levers

138 and 140 will be urged by their respective springs 16S and 174 to follow the bails. The return movement of the levers is preferably cushioned by means of a resilient strip 190 secured to the cross member 142 and extending the length thereof. Each lever opposite the cushioning strip may be provided with a lateral flange forming a heel for abutment against the strip as shown in FIGS. 2, 3 and 4. To guide the levers in their movements, the cross member 142 may be provided along its upper and lower edges with combs, indicated at 192 and 194 respectively, in the slots of which the levers are disposed for guidance in their movement.

Normally, as earlier mentioned, the pointed end of the lower actuator or lever 140 is received in its respective notch of its associated type carrier and upon move ment of the bails outwardly away from one another it will be urged by the spring 174 to follow the lower bail and in so doing move the carrier 38 and its respective type bar downwardly to cause the upper groups of characters on the faces of the type bar to traverse the printing line position. If, on the other hand, the bell crank lever 152 is oscillated slightly counterclockwise it will move the pointed end of the upper actuator or lever 133 into engagement with its respective notch 146 in the type carrier, which simultaneously withdraws the lower lever from its notch. The movement of the upper lever in following its bail will cause the carrier and its type bar to move upwardly thereby causing the lower sets of characters on the type bar to pass by the printing line position.

Rocking movement of the bell crank lever 152 is ptovided by a push rod 196 which, as shown in FIGS. 2 and 3, abuts a at 198 provided on the bell crank lever. The movement of the push rod 196 is controlled by an electromagnet 200 carried by the bank of magnetic devices 66. The armature 202 of the electromagnct is coupled to the push rod and upon energization of the electromagnet it will urge the rod outwardly thus rocking the bell crank lever counterclockwise to produce the shift in position of the two

levers

138 and 140. Associated with each bell crank lever is a spring 204 connected at one end thereto and at the opposite end to any fixed portion of the machine such as a flange projecting from the housing for the bank of magnetic devices 66, this spring yieldingly resisting the counterclockwise movement of the bell crank lever and returning the same to the initial starting position following de-energization of the electromagnet 200. The head 206 on the push rod may serve as a spacer which upon abutment with the adjacent wall of the bank 66 limits further clockwise movement of the bell crank lever and resets the two levers in the normal starting position thereof shown in FIG. 2.

It is evident, therefore, from the description thus far, that no signal is required to energize an electromagnet to cause the lower lever 144 to move the type carrier and type bar downwardly and in the absence of a signal this would occur during each line printing cycle. However, if the electromagnet 200 is energized by an electrical pulse applied thereto, as will be later described, it will shift the positions of the two

levers

138 and 140 and cause the former to engage the type carrier and move the same upwardly in timed sequence with the outward movement of the upper bail 160. It is to be noted that the two

levers

138 and 140 are not required to following the movement of their respective bails but are yieldingly urged to do so by the springs 16S and 174.

When the type carrier 38 is moved vertically, one or the other of the sets of

teeth

132 or 134 corresponding respectively to the characters on the upper and lower half portions of the type bar are moved past a position arresting device including a rockable shoe 210 having teeth engaging portions at each end thereof. When a particular selected character is opposite the platen, the shoe is urged into engagement with the associated tooth corresponding to that character. For this purpose, the shoe 210 is articulated as at pivot 212, the latter being carried by the upper end of a bell crank 214 which in turn is pivoted at its lower extremity as at 216 on a transverse frame member 218. A spring 220 engaging an upper arm portion of the bell crank 214 at one of its ends and secured to a hook portion 222 affixed to the transverse frame member 218 at its other end yieldingly urges the bell crank in a clockwise direction. In its normal position the shoe 210 is free of the toothed edges of the type carrier 38 and thus permits movement of the two sets of teeth past the shoe member. Upon receipt of a code signal an electromagnet 224 of the bank of magnets 70 will become energized and attract its armature 226 which in turn will impart movement to push rod 228 to urge the bell crank 214 in a counterclockwise direction against the tension of the spring 220. Depending upon which direction the carrier 38 is in motion past the arresting shoe 210, the upper or lower outer edge portions of the shoe may engage either set of

inclined teeth

132 or 134 along the type carrier. When so engaged, the shoe holds the carrier and its type bar from further vertical movement. This in turn restrains further swinging movement of the

actuator lever

138 or 140, `as the case may be, from following its respective bail. The bail springs 168 and 174 stretch under these circumstances as the bails continue to swing to their outermost positions. Disposed above the upper edges of the shoes and bell cranks 214 is a transverse -frame member 230 which includes comb-like slots 232 which restrain the bell cranks against lateral or sidewise movement during their pivotal travel. The engagement of the shoe with a tooth of either set of teeth disposed along the edge of the carrier completes the character selection for its associated type bar.

Thereafter, in the printnig cycle as previously mentioned the type bar 30 and carrier 3S may be moved forwardly toward the platen to make the printing impression on the document. The forward movement of the carrier is provided by a slight fulcruming action thereof about the upper terminal end of the base of the slot of the comb member 13D in which it is guided. It will be recalled that at this time in the printing cycle the turn arresting lever 166 pivoted thereto has been moved to bring the wheel into locking engagement with the sleeve 90. To provide the impacting motion of the type bars, the previously mentioned hammers 36 are slidably guided in slots of

comb members

236 and 238 which extend transversely between the inner surfaces of the

side plates

22 and 24. The forward end portion of each hammer is reduced in height to provide a head for abutting the rear side of the associated carrier at the sarne elevation as the printing line position on the platen, The rearward portion of each hammer 36 is generally arcuately shaped as indicated at 243 so as to partially surround the hammer cam drive shaft 32 and includes a right angle heel shaped insert 244 of high wearing quality located on the inner edge of the extremity of the arcuate portion of the hammer.

The hammer drive shaft 32 includes a pair of drop-off cut-outs located 180 apart and extending substantially the length of the shaft. The heel portion 244 of each hammer is urged into the cut-outs when the latter are brought into alignment therewith. Each hammer is powered for forward movement by a spring 246 which is connected at one of its ends to the crest of the arcuate portion 243 of the hammer land at its opposite end to a post 24S projecting upwardly from the comb member 236. Thus when one of the drop-off notches of the hammer shaft 32 is opposite the heel portion of the hammer 36 the spring 246 urges the hammer forward an amount equal to the depth of the notch and in doing so it abuts and moves the type carrier 38 and its associated print bar 3) toward the platen thus to make a printing impression upon the document 2S. It is understood that for visible recording a suitable inked ribbon or the like is interposed between the hammers and the document. It is observed that the lateral portion of the heel 244 of each hammer rides on the upper surface of a transverse guide member 250 bridging the space between the

side plates

22 and 24 and supported thereby. Further rotation of the hammer shaft 34 will cause the camming surface thereof to retract the hammer 36, and at the same time thereby stretch the power springs 246, so that the hammers are restored to their neutral position as shown in FIG. 2, prior to the start of a further printing cycle.

For resetting the hammers, each hammer 36 is provided with a forward hooked extension 240 which, as best shown in FIG. 14, overlies the rear side portion of its associated type carrier 38 and is received in an elongated vertical recess 242 of the carrier. The extension moves with Ithe hammer and is ineffective when the harnmer drives the carrier forwardly to make a printing impression. However, when the hammer is returned to its starting position, the hooked end of the extension engages the rear wall of the recess 242 and retracts the carrier to its normal position. At times during the cycling of the machine one or more of the type carriers and their respective type bars may not be vertically moved. To avoid impact of such unmoved type bars with the document, the rear edges of the carriers 3S, as shown in FIG. 18, are each provided with a notch 245. In the neutral position of the carriers, these notches are in line with the path of travel of the heads of the hammers and the heads enter these notches without abutting the carriers and thus avoiding applying an impact force thereto.

With reference now to FlGS. 2 and 4, provision is made for disabling each type bar and its carrier at its column position along the printing line. This enables the operator to vrender ineective cert-ain of the type bar operating mechanisms to obtain .a desired format of printed material on the document or to immobilize a useless group of type bars if the document is shorter in width than the row of type bars in the machine. For this purpose each upper actuator lever 138 is provided with an inclined surface 256 :at `its rearmost extremity. Associated with each such lever is a manually Ioperable arm 25S pivotally mounted on a pin 266 within a slot of a transverse comb member 262 aixed in any suitable manner to the machine such as the wall of the housing for the bank of magnetic devices 264. The arm 25S includes an enlarged or lobe portion 266 serving as a cam which when the yarm is rotated in the clockwise direction to full line position shown in FIG. 4 eng-ages the previously mentioned surface 256 to thrust the upper lever i138 in the forward direction. When so rota-ted against the action of spring 264 the toe portion 144 of the upper lever 138` will move into its mating notch 146 of type carrier 38, but not sufciently to fully withdraw the toe portion 148 of the lower lever 140 from its mating notch 150. With both levers so engaged in their associated type carrier, as shown in FIG. 4, the outward movement of the upper and lower bails 16)t and 162 will merely stretch their associated springs .168i and 174 without imparting any motion to the type carrier 38. 1t is evident in this condition that the two bails exert through their respective associated levers 13S and 14S equal and opposite forces on the associated type carrier 33 and thus no total movement accrues to the type car- =rier. To releasably hold each arm 253 in disabling or nondisabling position, a spring detent 261 -is provided which is yieldingly received in spaced notches on the pivoted end of the arm in the manner illustrated in FIGS. 2 and 4.

The marmer of absorbing the impact forces occurring during Contact of the printin-g type bar 30 with the platen 26 `and paper 2S is best shown in FlGS. 15 and 16. With reference rst to FIG. 15, it is observed that the two bearing portions 78 and S2 of each type carrier 38 are slightly elongated in the direction of its printing impact movement, shown greatly enlarged for clarity. The lower bearing portion 30, not shown in FIG. 15, is similarly elongated. The spindle extensions 72 and 74 of each type bar 30, as well as the intermediate spindle portion 76 thereof, are thus provided with a slight play in the carrier yin the fore `and aft direction of movement thereof. Normally the resulting slight clearance, shown at 73 for the top spindle 72, will be at the right of the spindles of the type bar as illustrated in FIG. 15. The type bar and carrier assemblies yare so designed that when a selected face of `a type bar is in impact printing position, a clearance substantially equal to that for the type bar spindles is provided between the apex 77 of the type opposite to the selected face and :the forward edge of the type carrier 38. This clearance is indicated at 79 in FIG. 15 and extends the length of the type bar. When, however, the type carrier and associated type bar have been moved forwardly to strike the platen, the apex 77 is brought into line contact with the leading edge of the carrier 38 and correspondingly the clearances for the type bar spindles designated by

reference characters

73 and 75 in FIG. 15 have correspondingly been absorbed and now appear to the left of the spindles as shown in FIG. 16. By means of this provision the sheer stresses which would occur at the spindle portions are eliminated and the impact force is transmitted from the leading edge of the carrier to the confronting apex 79l of the type bar along the length thereof.

To provide the torque to rotate the type bars 30 in their respective carriers 38, a common means for all the type bars is provided. In the illustrated embodiment of the invention such means comprises the two previously mentioned rack bars 62 yand 64 which, as shown in FIG. 1, are square shaped in cross-section for the major portion of their lengths within the machine. For supporting and slidably guiding these -support bars for reciprocal motion each bar is provided with a cylindrical extension at each end thereof extending through suitable bushings in the adjacent side plate of the machine. One such extension for the rack bar 62 is indicated at 270 in FIG. 1, and that for the rack bar 64 at 272. The inner faces of thc rack bars, as illustrated in FIG. `l, are provided with teeth which mesh with the elongated pinions 86 carried on the lower ends of the torsion bars 84. To reciprocate the rack bars in unison, but in opposite directions to one another, an operating connection is provided between the cam barrel 58 and the

cylindrical extensions

270 and 272 located adjacent thereto. The illustrated connection comprises a rocking arm 274 pivoted adjacent one end on bracket 276 on an axis indicated at 277 located between the two extensions of the rack bars. The other end of the rocking arm is provided with a cam follower 278 which rides in the groove 60 of the cam barrel 58. The shape of the groove 60 is `so designed that during one 1'0- tation of the cam barrel it rocks the arm 274 first in one direction and then in the other and thereby imparts a reciprocating motion to the rack bars 62 and 64 causing them in 'turn to move in one direction opposite to one another and then return in the opposite direction. The reciprocating movement of the rack bars applies torque to the type bar pinions 86 while keeping their axes stationary, and in turn this torque is transmitted by the torsion wires 84 to the type bars. Although the pinions 86 are lifted or lowered concurrently with the type bars, nevertheless due to their elongated extent the pinions maintain meshing engagement with the teeth of the rack bars regardless of the position they :assume with respect thereto.

The three-faced or prismatic construction of the type bars 30, especially when their apexes are beveled or charnfered in the manner previously described, enables them to be assembled or packed in very close proximity to one another as shown by the group of type bars in FIGS. 17 and 18. Regardless of whether selected ones of the type bars are locked against rotary motion or not, they are sufficiently clear of one another to rotate on their axes relative to one another. As shown in FIG. 18, two of the Itype bars, the third and fifth of the group, have been restrained from further rotary movement to present one of their faces for printing while the remaining 4three type bars are shown as undergoing equal angular displacement beyond the held type bars. During each machine cycle the type bars of the present embodiment of the invention are oscillated about their respective axes 240 to successively bring their respective faces opposite to the platen. By virtue of the common drive means for applying torque to all of the type bars, they will, unless restrained by the locking devices, oscillate the same angular distance and in the same direction in unison about their respective axes and thus by this provision avoid the necessity of providing individual means for applying a separate torque to each type bar. FIG. 17 exemplifies the action of a group of the type bars 30 with respect to the platen 26 and a document 28 thereon. Several of the type bars 12 are shown in this figure at the instant of impact with the document to print two words while the remaining type bars are shown as having been rendered inelective so as to provide the spaces between the words.

As illustrated in FIGS. 1 and 2, the banks of

electromagnetic devices

66, 68 and 70 are shown as mounting their respective devices in groups of four, each group occupying a common vertical plane. This compact arrangement is desired because of the larger dimensions of these devices as compared with the width of the type bars and their associated operating elements. In the arrangement shown, each such group of four electromagnets have their respective operating connections made to four ad jacent type bar operating assemblies in the machine. Thus, it is to be understood that the

push rods

116, 196 and 228, similar to those already described, are connected to and actuated by the armatures of the three remaining electromagnets in each grouping thereof in the banks. As shown in the drawings the push rods may be of varying lengths to reach the armature to which they are connected.

Although electrical signals may be derived from any suitable source for energizing the electromagnetic actuators in the

banks

66, 68 and 70, one desirable method of input data decoding is shown on FIG. 19. The input data are assumed to be obtained from a record member, such as a card 280, FIG. 19a, similar to cards used by some tabulating business machines. The card contains the coded information for printing a line of characters in one cycle of machine operation. This card enters and is retained in a card sensing chamber 281 provided with brushes 282 which provide circuit continuity through punched holes 283 in said card. The illustrated card 280 has the coded holes therein provided in crossing rows and columns, the rows extending vertically in FIG. 19a and the columns extending horizontally. As indicated by the brackets in the figure, the card is divided into two zones, the first zone containing rows designated R, X and O and the second zone containing rows designated 1 to 9 inclusive. Each column on the card is representative of a particular columnar printing position produced by the machine, the order of the card columns corresponding to the order of the type bars from one to the other end of the platen. The information in the first zone of the card determines the direction of vertical movement of the type bars, whether up or down, and also determines the selection of one of the three faces of the type bars to be presented to the platen for printing.- The information in the second zone of the card determines the positions at which type bars will be arrested in their vertical movements.

For the purpose of this description it is assumed that the presence of an R hole in each column of the card selects one side or face of the type bar 30 corresponding to the card column, the presence of an X hole another side of the type bar, and the absence of either R or X hole the third side of the type bar. The presence of an O hole in a card column causes the corresponding type carrier 38 to rise, the absence of an O hole causes the carrier to depress. The presence of a 1 to "9 hole a given card column will cause the arrest of the vertical motion of the corresponding type carrier 38 at the elevation corresponding to the number of the hole. It is understood that the coding on the record member and the arrangement of the letter characters on the type bars may be varied.

The circuit shown in FIG. 19 is representative of a control circuit for one type bar operating assembly, it being assumed that a similar circuit is provided for each of the remaining type bar operating assemblies. The sensing of holes in the card rows R, X and O will energize corresponding storage relays 284, 285 and 286.

Relays

284 and 285 continue being energized through the provision of current limiting resistors 287. The third relay 286 need merely be pulsed to momentarily close its circuit through switch 302 which is suicient to shift the upper lever 133 toward the carrier and bring its toe portion into engagement with its respective notch 146 where 4the toe portion will be retained through the upward movement ot' the carrier by sliding eng-agement of its heel plate along the side of the cross frame member 142. The three

relays

284, 285 and 286 establish a circuit continuity from the input line 364 to the turn arrest electromagnet 118 and the direction control electromagnet 200i. Switches 291, 292, 293 and their respective operating cams 288, 239, 290, which are driven synchronously by the bail drive shaft 34, cause through turn arrest actuator 118 the type bar to be arrested at the position pre- 1etermined by the energization of the

relays

284, 235 and 286 and to release actuator 118 at the same point of the return stroke of the rack bars 6'2 and 64, thus avoiding unnecessary oscillation of the arresting sleeve 99 and subsequent overstressing of the torsion wire 84. Switches 28S, 2%9 and 2% determine when and how long the turn arrest -actuator 118 is energized.

Circuit breaker 294, which may be operated from shaft 341, causes all relays to drop out at the proper cycle point. The elevation stop actuator 224 becomes energized through one of the l to 9 holes of the card by the provision of a rotating brush commutator 2% which may be fixed to shaft 34 for moving in synchronism with the type carrier 38. When brush 2% senses a hole in the card it closes circuit to relay 30d energizing the same and closing switches 36S and 210v and providing a closed circuit from input line 3M through switch 311i to stop electromagnet actuator 224. Thus, when rendered conductive, brush 295 will select one of the nine teeth contained in either set of

teeth

132 or 134 in the type carrier 38 in either the up or down stroke thereof, whichever direction has been determined by the presence or absence of a O hole in the card.

As an example of the printing operation, if it is desired to print an ampersand & by one of the type bars, one of the columns of the card 280 in FIG. 19a so designated in the left margin is provided with punched holes in each of the 0, X and 7 row positions thereof. The presence of the O hole causes energizing of relay 286 and results in the movement of upper lever 138, which requires only a momentary actuation of electromagnet 2% as previously described. The presence of the i hole energizes relay 235 and closes

switches

297 and 301. Relay 236 establishes circuit continuity through Contact 362 from the input line 3114 to elevation actuator 299 thus causing the selection of an tip-stroke for the type carrier. At the same time circuit continuity is made from the input line through switch 292, now closed by cam 2S9 and closed relay Contact 301, to tum-arrest actuator 113 at 153 of the machine cycle. Upon energization, actuator 118 positions the type bar so that the side thereof containing the & is facing toward the platen. As shown in FIG. 6, the ampersand 8a is spaced seven character positions from the neutral or mid-point of the type bar. Simultaneously the rising of the type carrier continues and when the brush 295 senses hole 7 of the card the electromagnet actuator 224 stops further movement of the type carrier and associated type bar. After completion of the print cycle, the rotation of cam 289 will bring its drop-off surface opposite to switch contact 292 opening the same. This will release the turn arresting actuator 118 at the same point of the return stroke of the rack bars 62 and 64.

As another example, when coded information is indicated on the card 2S@ for a number, such as 5, to be printed, there will be an absence of punched holes at the R, X and O positions in the column of the card corresponding to the selected type bar. The absence of an O causes the type carrier to be depressed. Since none of the

relays

284, 285 and 286 become energized, the circuit is closed to the turn arrest actuator 11S by the closing of switch 295 by cam 22d during the rotation of the latter from 216 to 280 thus placing the side 14 face of the type bar containing number characters opposite to the platen, and the type bar is arrested at the fth tooth during its down stroke when commutator brush 295 senses the number 5 hole on the card. The printing cycle will be completed in the manner described in the previous example.

Having described a preferred form of the invention it will be understood that other forms thereof will fall within the scope of its teaching and the following claims:

What is claimed is:

1. In printing apparatus, an elongated type carrier, an elongated multi-faced type bar journalled for rotation about its longitudinal axis in said type carrier, each face of said bar having two longitudinally spaced apart groups of printing characters thereon, one group of such characters disposed normally above and the other group of such characters disposed normally below a printing line position of the apparatus, means for linearly moving the carrier and the type bar together in opposite directions to cause either the upper or the lower groups of characters to pass the printing position, a pawl structure and means for causing the structure to engage the carrier during its lineal movement to interrupt said movement, torsion wire means connected to the type bar, means for applying torque to rotate the torsion wire means and the type bar during said lineal movement, and means for arresting rotation of the type bar while torque is applied to the torsion wire means, whereby a given type character contained in a given group of characters on a given face of the type bar may be presented for printing.

2. In a printing device, a type carrier, an elongated multi-faced type bar journalled for rotation on said t-ype carrier, each face of said bar having two spaced apart groups of type characters thereon, one group disposed normally above and the other below a vertical printing line position of the printing device, means for selectively moving the carrier lineally to cause either group of characters to pass the printing position, a pawl structure and means for causing the structure to engage the carrier during its lineal movement to interrupt said movement, torsion Wire means connected to said type bar, elongated pinion means connected t0 said torsion wire means, a pair of slidable members each having a series of rack teeth, said members being arranged to move in parallel paths, said pinion means mutually coacting with the teeth of each of said members, means connected to said members to cause the same to move in opposite directions and to impart rotative movement to sai-d pinion means and said type bar through said torsion wire means Without displacement of said pinion means in a direction normal to its axis, a sleeve member having a like number of faces as said type ybar encircling said torsion wire and secured to said type bar, wheel means, and means for causing the twheel means to move into engagement with a pair of adjacent faces of said sleeve member to stop the rotation of the same whereby said torsion wire permits said pinion to complete its rotation while the sleeve member is locked against rotation while at the same time permitting lineal movement of the type lbar and pinion under the action of the lineal moving means associated with the type carrier.

3. In a printing device having a platen, a type carrier, an elongated type bar exhibiting the shape of a triangular prism having type characters on its three faces thereof, said faces being disposed to form an equilateral triangle,

f means for selectively moving the carrier lineally to cause the characters to pass a printing position, means for engaging the carrier during its lineal movement to interrupt said movement, means for rotating said type fbar to present one of said faces to said platen, said type bar being journalled on said carrier for rotation about its axis such that when one of said faces is disposed in its printing position relative to said platen the apex of the type bar opposite to said face is juxtaposed along an edge of the carrier, said type bar being journalled in said carrier with sufficient clearance to permit relative movement 15 therebetween and toward one another to enable said apex to engage said edge of said carrier in line contact therewith, and means for impelling the type bar and carrier toward the platen whereby the impact stresses of the type bar with the platen are absorbed and distributed in line contact of said apex with said edge of said type carrier.

4. In printing apparatus, a type carrier, a multi-faced type bar journalled for rotation in said carrier about its longitudinal axis, means for moving the type bar along said axis, yieldable means aixed to said bar and aligned with said longitudinal axis, means connected to said yieldable means for applying torque thereto to effect rotation of said type bar and to present its faces sequentially to a printing position, and means for arresting the rotation of said type bar while thereafter increasing the torque applied to said yieldable means so that a selected one of its faces is stopped in a printing position whereby said yieldable means is twisted about said longitudinal axis.

5. In printing apparatus, a type carrier, an elongated multi-faced type bar journalled for rotation about its longitudinal axis in said carrier, means for moving said type bar along said axis, torsion means affixed to said bar, means for applying torque oscillatibly to said torsion means to effect rotation of said type bar in opposite directions about its longitudinal axis to present its faces sequentially to a printing position, and means for arresting the rotation of said type bar so that one of its faces is stopped with a selected type in said printing position while the further torque applied by said torque applying means to said torsion means is absorbed in deformation of the latter.

6. In printing apparatus, a multi-faced type bar journalled for rotation about its longitudinal axis, torsion means secured to one end of said type fbar, pinion means secured to said torsion means, rack means coacting with said pinion means for applying torque to said torsion means to turn said type bar about its longitudinal axis, and means for arresting the rotation of said type bar while said rack means continuously applies torque to rotate the pinion means which operates to twist said torsion means.

7. In printing apparatus, a multi-faced type bar journalled for rotation about its longitudinal axis, a torsion rod connected at one end to said type bar, a pinion secured to the opposite end of the torsion rod, means for rotating said pinion means to effect turning movement of said type -bar about its longitudinal axis so as to present its faces sequentially to a printing position, and means for selectively arresting the turning movement of said type bar to dispose one of its faces in the printing position while said rotating means through said pinion continues to apply torque to the torsion rod, said torsion rod acting to absorb by twisting on its axis the continued application of the torque after the type bar has been arrested.

8. In printing apparatus, a plurality of multi-faced type [bars individually journalled for rotation about their respective longitudinal axes, means for oscillatibly rotating the type bars about their respective axes including a torsion element individual to each type -bar and serving to transmit driving torque thereto, the oscillatibly rotating movement applied to each type bar sequentially presenting its type faces to a printing position in the apparatus, rotation limiting means in one position thereof individual to each type bar for selectively arresting its rotation while torque is concurrently applied to the torsion element to rotate the latter, each torsion element twisting on its axis to absorb the torque applied thereto after the rotation of its respective type bar has been arrested, said rotation limiting means being movable to a second position out of engagement with the type bar whereby said torsion element is restored to its untwisted position, and means for moving said rotation limiting means between said one and second positions.

9. In printing apparatus, a like plurality of elongated multi-faced type bars each journalled for rotation about and for bodily movement along its axis, a pinion associated with each type bar, a torsion element connecting each type bar with its associated pinion, rack means common to said pinions and operable to apply torque thereto to rotate the torsion elements and the type bars in unison, means for bodily moving said type bars along their respective longitudinal axes and carrying their respective pinions along therewith while the same are being rotated by said rack means, and means for selectively arresting the rotation of the type bars to present one of their respective faces in a printing position while torque is continuously applied by the rack means to rotate .the pinions, said torsion elements thereby twisting on their respective axes to absorb the applied torque after the rotation of their respective type bars have been arrested.

l0. In printing apparatus, an elongated print member having portions of its longitudinal extent shaped in the iform of a three-faced prism, type characters carried on each of the three faces of one of the prism portions of the member, means journalling the opposite ends of the print member for rotation about its longitudinal axis,

means for rotating the print member on its axis to present the different faces thereof for printing, and a per-ipherally grooved wheel engageable with any one of the apexes of another prism portion of the print member and acting when so engaged to releasably hold the member from rotation.

`ll. In a printing apparatus, a plurality of type carriers, a plurality of elongated type bars each in the form of a equiangular triangular prism and corresponding in number to said carriers, a plurality of type characters disposed upon each of the lateral faces of said prism, said type bars being closely spaced one to another and each, journalled for rotation about its longitudinal axis in a corresponding carrier, a pair of rack means common to al1 said type bars, means for actuating each rack means in an opposite direction with respect to the other to thereby rotate said type bars about their longitudinal axes, whereby the lateral edges of each type bar formed by intersections of its lateral faces thereof are in approximate touching contact with lateral edges of type bars on each side of and immediately next adjacent thereto.

References Cited in the le of this patent UNITED STATES PATENTS 543,164 Weiss Iuly 23, 1895 723,567 White Mar. 24, 1903 1,333,890 Wright Mar. 16, 1920 1,542,223 Dolph June 16, 1925 1,926,891 Bryce Sept. 12, 1933 2,157,035 Torkelson May 2, 1939 2,320,810 Carroll Iune l, 41943 2,577,092 Sampson Dec. 4, 1951 2,709,959 Beattie June 7, 1955 2,847,105 Carroll Aug. 12, 1958

Claims

4. IN PRINTING APPARATUS, A TYPE CARRIER, A MULTI-FACED TYPE BAR JOURNALLED FOR ROTATION IN SAID CARRIER ABOUT ITS LONGITUDINAL AXIS, MEANS FOR MOVING THE TYPE BAR ALONG SAID AXIS, YIELDABLE MEANS AFFIXED TO SAID BAR AND ALIGNED WITH SAID LONGITUDINAL AXIS, MEANS CONNECTED TO SAID YIELDABLE MEANS FOR APPLYING TORQUE THERETO TO EFFECT ROTATION OF SAID TYPE BAR AND TO PRESENT ITS FACES SEQUENTIALLY TO A PRINTING POSITION, AND MEANS FOR ARRESTING THE ROTATION OF SAID TYPE BAR WHILE THEREAFTER INCREASING THE TORQUE APPLIED TO SAID YIELDABLE MEANS SO THAT A SELECTED ONE OF ITS FACES IS STOPPED IN A PRINTING POSITION WHEREBY SAID YIELDABLE MEANS IS TWISTED ABOUT SAID LONGITUDINAL AXIS.