US3429414A

US3429414A - Printer with print hammer mounted on movable carriage

Info

Publication number: US3429414A
Application number: US632955A
Authority: US
Inventors: Wilburn F Bradbury
Original assignee: SCM Corp
Current assignee: SCM Corp
Priority date: 1967-04-24
Filing date: 1967-04-24
Publication date: 1969-02-25
Anticipated expiration: 1986-02-25
Also published as: FR1558773A; GB1203396A; NL6805728A; ES352122A1; GB1203394A; BE713078A; DE1301361B; GB1203397A

Description

' Feb. 25, 1969 w. F. BRADBURY 3,429,414

PRINTER WITH PRINT HAMMER MOUNTED ON MOVABLE CARRIAGE Filed April 24, 1967 Sheet of 2 7 lol IN V EN TOR.

WILBUKN F. BRADBURY u 5 BY W4 ATTORNEY Feb. 25, 1969 w. F. BRADBURY PRINTER WITH PRINT HAMMER MOUNTED ON MOVABLE CARRIAGE Sheet Z of 2 Filed April 24, 1967 us INVENTOR.

wmaurm F.BRADBUKY BY WW ATTORNEY 3,429,414 PRINTER WITH PRINT HAMMER MOUNTED N MOVABLE CARRIAGE Wilburn F. Bradbury, Northbrook, IlL, assignor to SCM Corporation, New York, N.Y., a corporation of New York Filed Apr. 24, 1967, Ser. No. 632,955 US. Cl. 197-82 Claims Int. Cl. 1341i 19/00, 1/32, 19/76 ABSTRACT OF THE DISCLOSURE There is disclosed a printer with a movable carriage having a print hammer cooperable with a rotatably mounted platen. A spring constitutes the sole means for driving the print hammer into printing cooperation with the platen and an electromagnet constitutes the sole means for driving the print hammer out of printing cooperation With the platen and for holding the print hammer out of printing cooperation. A record medium is fed between the print hammer and the platen by feed wheels mounted to provide contact between the record medium and the platen essentially only at a printing zone. The platen can have a plurality of platen elements with which the print hammer cooperates to print on the record medium. The carriage is selectively coupled and uncoupled with a feed screw which drives the carriage in forward direction from a start-of-line position. The feed screw is cyclically rotated a predetermined amount through a clutch. When the carriage is to he returned to start-of-line position, the carriage is uncoupled from the feed screw and latched in uncoupled position until the carriage is returned to start-of-line position, and simultaneously, a drive connection is established for the feed wheels so that upon rotation of the feed screw the record medium is fed.

The principles of the invention are illustrated as being carried out in a printer of the type disclosed in US. patent application Ser. No. 278,241, filed May 6, 1963, now Patent No. 3,324,240, patented June 6, 1967. This type of printer is especially useful in conjunction with radio signaling systems as well as the usual telegraphic signaling channels. The incoming signal causes movement of the print hammer between a first position out of printing cooperation with a vaned platen and a second position in printing cooperation with the vaned platen. An incoming signal can have for example forty-eight pulse units, up to thirty-five of which can be used to produce up to thirty-five marks in forming each symbol. Upon receipt of a start signal, the print hammer starts to move lengthwise relative to the rotating platen and the symbol character is progressively formed on the record medium by cooperation of the print hammer with the rotating platen. The position of one platen element at the printing zone relative to the cooperating face of the print hammer and the position of the face of the print hammer relative to the start-of-line position determines the position of each mark or dot on the record medium.

It is another feature of the invention to provide a unitary print hammer having a face and an armature, with the print hammer being movable between a first position wherein the face is out of printing cooperation with 3,429,414 Patented Feb. 25, 1969 a platen and a second position wherein the face is in printing cooperation with the platen, spring means acting on the print hammer and constituting the sole means for driving the print hammer from the first position to the second position, and an electromagent cooperable with the armature and constituting the sole means for driving the print hammer from the second position to the first position and for holding the print hammer in second position against the force of the spring means each time the electromagnet is deenergized, the spring means always drives the print hammer against the record medium at the same rate of speed, and yet no auxiliary devices are required to return the print hammer to, or hold the print hammer at, the first position, when the electromagnet is energized.

It is another feature of the invention to provide a. selectively operable drive for feed wheels which feed the record medium. A latch operated by an electromagnet is tripped to enable a drive connection to the feed Wheels. The drive connection specifically includes a cam which is also useful to relatch the latch.

It is another feature of the invention to provide a printer with a clutching arrangement which is relatively simple yet reliable which prevents backlash from being imparted tion of an electromagent, and which is relatched by an element of the clutch.

Other features of the invention will become more apparent from the following detailed description and the accompanying illustrative drawings, in which:

FIGURE 1 is a side elevational view of a printer in accordance with the invention;

FIGURE 2 is a fragmentary perspective view of the Side of the printer depicted in FIGURE 1;

FIGURE 3 is a fragmentary side elevational view showing various components in different positions from the positions shown in FIGURES 1 and 2;

FIGURE 4 is a front elevational view of the printer;

FIGURE 5 is a sectional view showing mainly the platen in relation to a carriage which carries a print hammer, the print hammer being shown in printing cooperation With the platen and the record medium between the platen and the print hammer being omitted for clarity;

FIGURE 6 is a side elevational view of the carriage;

FIGURE 7 is an enlarged fragmentary sectional view taken along line 7-7 of FIGURE 9;

FIGURE 8 is a fragmentary side elevationl view showing the side of the printer which is opposite from the side shown in FIGURE 1;

FIGURE 9 is a fragmentary view as viewed upwardly and rearwardly from the lower front part of the printer, showing the clutch much enlarged for clarity; and

FIGURE 10 is a fragmentary perspective View of the print hammer.

Referring now to the drawings, there is disclosed a printer generally indicated at 20 having a frame generally indicated at 21. The frame 21 has a pair of spaced apart

side plates

22 and 23 securely held in position by a frame member 24, a bar 25, and a guide rod or shaft 26.

As best shown in FIGURE 9, a platen generally indicated at 27 is rotatably mounted between the

side plates

22 and 23.

Mounting structures

28 and 29 are locked against rotation by

noncircular projections

30 and 31 which fit snugly in mating noncircular holes 32 and 33 in

respective side plates

22 and 23. The platen 27 is secured to an axle or shaft 34 mounted in

ball bearings

35 and 26. The

bearings

35 and 36 are mounted in a recess in the

respective mounting structures

28 and 29. The platen 27 is shown to have a vaned or fluted tube 37 having a plurality of equally spaced, parallel platen elements or edges 38 about its periphery. The elements or edges, extending the full length of the tube 37, have small flats at their peripheries as best seen in FIGURE 7. End plates 39 and 40, secured to the ends of the tube 37, are secured to the axle 34. Sound deadening material 41 is disposed within the tube 37 and between the end plates 39 and 40.

A record medium R is fed between the platen 27 and a face 42 of a print hammer 43 so that the record medium R is in contact with the elements 38 at the printing zone. While the face 42 is generally perpendicular to a cooperating vane 38 at the printing zone, the face 42 is slightly canted, as shown in FIGURE 4. The record medium R is preferably composed of treated paper so that when the print hammer 43 is driven against the record medium R, a contrasting mark is formed thereon. In the event it is desired to use an untreated record medium, an ink ribbon can be fed between the face 42 of the print hammer 43 and the untreated record medium, as disclosed in the abovementioned US. patent application. In the present application, the record medium is drawn from a roll R journalled in side plates 44 disposed at each side of the roll R. The side plates 44 are secured to the frame member 24 and to a record medium guide 45. The record medium R is drawn over the guide 45 by belts or feed wheels 46 and 47 and is fed through the printing zone and passes in front of a guide 48 secured to the bar 25. The guide 48 guides the record medium R away from the platen 27 and the feed wheels 46 and 47.

The record medium R is engaged by the feed wheels 46 and 47 which, as best shown in FIGURE 7, bring the record medium R into contact with the platen 27 essentially only at the printing zone. The printing zone is considered to be the place where the face 42 of the print hammer 43 and a ridge or vane 38 of the platen 27 can cooperate to make a mark on the record medium R. The feed wheels 46 and 47 surround the rotational axis of the platen 27. The feed wheels 46 and 47 are depicted as having greater outside diameters than the outside diameter of the platen 27, and the rotational axis 50 of the platen 27 is disposed between the rotational axis 51 of the feed wheels 46 and 47 and the printing zone. The greater the diameter of the feed wheels 46 and 47 relative to the diameter of the platen 27, the less contact there is between the record medium R and the platen 27. A pair of

mounts

52 and 53 each carry rotatably mounted

rollers

54 and 55 which press the record medium R against the feed wheels 46 and 47. Each mount 53 is urged toward its respective feed wheel by a spring 56 which abuts a stud 57 mounted by a respective side plate.

The feed wheels 46 and 47 are shown to be composed of frictional material such as rubber and are adhesively secured to annular members or hubs 58 and 59 composed for example of a good bearing material such as nylon. The feed wheels can have pins or sprocket teeth (not shown) which would engage in feed holes (not shown) in a record medium, if desired. The members 58- and 59 are rotatably mounted about hearing or mounting

structures

28 and 29. The members 58 and 59 have gears 60 and 61 formed integrally therewith. Gears 60 and 61 mesh with respective gears 62 and 62' secured to a shaft 63 which is rotatably mounted in

side plates

22 and 23. Rotation of the shaft 63 causes rotation of

gears

62 and 62 and respective meshing gears 60 and 61 to effect rotation of the feed wheels 46 and 47 A carriage generally indicated at 64 is mounted for travel lengthwise with respect to the platen 27 by the guide rod 26 and by a shaft 65. The carriage has a body 66 with an enlarged hole 67 through which the guide rod 26 extends. A U-shaped plate 68 has opposed

side plates

69 and 70 which straddle the body 66. Guide slots 71 and 72 in the

respective side plates

69 and 70 straddle the guide rod 26 for guiding the carriage 64. The housing 66 has a bore 73 in which a bushing 74 is secured. The shaft 65 is slidably received by the bushing 74. The shaft 65, along with the guide rod 26, slidably guide the carriage 64. An electromagnet generally indicated at 75 has a U-shaped core 76 and a coil 77 received about one leg 78 of the core 76. The other leg 79 of the core 76 is adjustably clamped to the body 66 by screws 80 which extend through enlarged bores (not shown) in the leg 79 and are threadably received by the body 66.

The print hammer 43 is generally L-shaped and has an integral armature 81. A thin strip of non-magnetic stainless steel 82 is welded to the armature to provide a small constant air gap between the ends of arms 78 and 79 and the armature 8-1. The core 76 extends the full length of the armature 81 from a pivot 83 about which the print hammer 43 is pivotally mounted to the free end of the armature 81. The core 76 is preferably composed of laminated U-shaped sections as is conventional. As the arm 79 of the core 76 is immediately adjacent the pivot 83, the air gap between the armature 81 and the leg 79 of the core 76 remains constant, whereas the air gap between the armature 81 and the leg 78 changes. When the coil 77 is energized, the print hammer 43 is pivoted in a clockwise direction as viewed in FIGURE 5 until the strip 82 secured to the armature 81 contacts the end of the leg 78- of the core 76. In so doing, the force of the compression spring 84 is overcome. When the print hammer 43 is thus pivoted upon energization of the coil 77 the face 42 of the print hammer 43 moves out of printing cooperation with platen 27. The spring 84 is the means for driving the face 42 into printing cooperation with the platen 27, and the electromagnet 75 is the sole sole means for driving the face 42 into printing cooperation with the platen 27 and for holding the print hammer 43 out of such printing cooperation against the force of the spring 84. Thus, the need for auxiliary means for returning the print hammer 43 and holding the print hammer 43 out of cooperation with the platen 27 is obviated. A set screw 84' adjustably received in a threaded bore 85 in the body 66 can be turned to regulate the force ex erted by the spring 84 on the print hammer 43. The set screw 84' has an integral guide 86 for retaining the spring 84 in position and for enabling the spring 84 to expand and contract but otherwise preventing it from deflecting.

In US. patent application Ser. No. 278,241, the print hammer magnet is operated by a current pulse unit to drive the print hammer into printing cooperation with a platen element, whereas in the present application the print hammer 43 is driven into printing cooperation with a platen element 38 by the spring 84 as the result of a no-current pulse unit.

The carriage 64 is coupled and uncoupled by coupling means having a pawl 90 pivotally mounted to the body 66 by a pivot 91. The pawl 90 has a threaded segment 92 having a plurality of threads which, in the position shown in FIGURE 5, couple with the threads of a worm or feed screw 93. The pawl 90 is shown to be uncoupled from the feed screw 93 in FIGURE 6. An extension 94 of the pawl 90 extends into longitudinal groove 95 of the shaft 65 to urge the pawl 90 out of coupled position with respect to the feed screw 93. An adjustable stop 98 limits the pivotal movement of the pawl 90 away from coupled position. When the shaft 65 is in the position shown in FIGURE 5, the force of the spring 96 having been overcome, the extension 94 bears against an elongated fiat 97 of the groove 95. As the carriage 64 moves in forward direction, away from the start-of-line position, the extension 94 slides in contact with the flat 97. The pawl 90 can be provided with a roller (not shown) at the extension 94 so that there would be rolling contact with the flat 97, if desired. When the shaft is rotated into the position shown in FIGURE 6, the spring 96 is shown to urge the pawl out of coupling engagement with the worm 93.

An electric motor 99 (FIGURE 1) mounted by the frame member 24 drives a toothed pulley 100. The pul ley 100 drives a toothed endless belt 101, which in turn drives a toothed pulley 102. The pulley 102 selectively drives the feed screw 93 through a clutch generally indicated at 103. The feed screw 93 has marginal shaft ends 104 and 105 journalled in

respective side plates

22 and 23. A gear 106 and a cam 107 are secured to the shaft end 104 while the clutch 103 is connected to the marginal end 105. The gear 106 meshes with a gear 108 secured to the axle 34 of the platen 27. The pulley 101 is considerably smaller than the pulley 102, and the gear 106 is considerably smaller than the gear 108. The platent 27 thus rotates at a considerably slower speed than the speed to the motor shaft to which the pulley 100 is secured.

Referring now to FIGURE 9, the clutch 103 is shown to include an annular member 109 received about the shaft end 105 of the feed screw 93. The annular member 109 is secured to the shaft end 105 by a set screw 110 and has an axial slot 111 into which an end 112 of a coil spring 113 projects to prevent the spring 113 from rotating relative to the annular member 109 and the shaft end 105. A tubular clutch sleeve or element 114 is rotatably received about a shoulder 115 of the annular member 109. The end of 112 of the spring 113 is tightly abutted against the shoulder 116 of the annular member 109 while the opposite end of the spring 113 rides on a hardened hub 117 to which the pulley 102 is secured. The spring 113 encircles the annular member 109 and the hub 117. A bushing 118, secured in a bore 119 in the bearing 117, is rotatably received about the shaft end 105. A collar 120 secured to the shaft end 105 by a set screw 121 prevents the bearing 117 and its bushing 118 from shifting. A pin 122 mounted in the clutch element 114 has a stop 123 engageable with a shoulder 124 of the bearing 117. The end 113 of the spring 113 abuts the stop 123.

The clutch element 114 is rotatably received about a shoulder 126 of the bearing 117.

A latch generally indicated at 127 (FIGURE 8) is shown to include a latching element or member 128 having an armature 128 for an electromagnet 129. The latching element 128 is pivotally mounted on a pivot pin 130 secured to the side plate 23 and is normally held out of attracted position by a tension spring 131. The electromagnet 129 includes a coil 132 and a U-shaped core 133 secured to the side plate 23. A unitary lever 134 mounted on a pivot 135 is urged counterclockwise by a tension spring 136. With continued reference to FIGURE 8, the lever 134 has a latch arm or element 137 shown latched against counterclockwise movement by latch member 128, a follower arm 138 shown to be in the path of a cam 139 on the clutch element 114, and a stop arm 140 shown abutted against the face of a tooth 141 on the clutch element 114. When the coil 132 is energized the latch member 128 is pivoted counterclockwise, thereby causing the stop arm 140 to unblock the tooth 141 on the clutch element 114 and causing the follower arm 138 to ride on the clutch element 114 in the path of the cam 139. The cam 139 engages the follower arm 138 and drives the lever 134 clockwise far enough, against the urging of the spring 136, so that the latch member 128 can again engage the latch element or arm 137 and hold the lever 134 latched as indicated in FIGURE 8. When the stop arm 140 unblocks the tooth 141, the spring 113 of the clutch 103, upon frictional engagement with the clutch surface 117 of the hub 117, causes the shaft end 105 of the feed screw 93 to be driven. When the clutch element 114 has rotated until the tooth 141 comes into abutment with the stop arm 140, the rotation of the clutch element 114 is arrested. A pawl 142, pivotally mounted on a pivot 143, is urged into contact with the annular member 109, in alignment with a tooth 144, by a torsion spring 145. The pivot 143 is adjustably mounted at any location in an arcuate slot 146 in the side plate 23. Although the rotation of the clutch element 114 is arrested when the tooth 141 strikes the stop arm 140, the inertia of the feed screw 93 and attached gear 106, cam 107 and annular member 109 causes the annular member 109 to continue to rotate through a very slight angle until the pawl 142 clears the tooth 144 and is pivoted into abutment with the face of the tooth 144, as indicated in FIG- URE 8. Such continued rotation or overtravel of the annular member 109 relative to the clutch element 114 causes the spring 113 to unwind and expand to a greater inside diameter than the outside diameter of the hub 117 because the end 112 of the spring 113 continues to rotate relative to the end 113' of the spring 113 which is blocked by the stop 123 when the rotation of the clutch element 114 is arrested. Such overtravel must be sufiicient to release the spring 113 from gripping contact with the clutch surface 117 and further prevents any backlash in the feed screw 93. Each time the stop arm 140 unblocks or releases the tooth 141 spring 113 contracts and grips the clutch surface 117 and the clutch 103 is considered to be engaged.

Referring now to FIGURES 1 through 4 in particular, there is shown a lever 150 having a U-shaped end 151. The lever 150 is pivotally mounted on and relative to the shaft 65. A bracket 152 is secured to the lever 150. A tension spring 153 is attached at one end to the side plate 22 and at its other end to the bracket 152, thereby urging the lever 150 clockwise, as viewed in FIGURES 1 or 3 for example. A latch generally indicated at 154 includes a latch member 155 which cooperates with a latch shoulder 152 of the bracket 152 to latch the lever 150 in its counterclockwise position as viewed in FIGURE 1. The latch member 155, pivotally mounted about a pivot 15 7 is normally urged clockwise away from the electromagnet generally indicated at 158 by a spring 156. The latch member 155 has an armature 155' attractable by the electromagnet 158. The electromagnet 158 is shown to have a coil 159 and a U-shaped core 160 secured to the side plate 22. When the coil 159 is energized, the latch member 155 is urged counterclockwise from the position shown in FIGURE 1 to the position shown in FIGURE 3, thereby enabling the spring 153 to pivot the lever 150 about the shaft 65. In so doing, a roller 161, in the path of the cam 107, is pivoted against the low point of the cam 10 7 as indicated in FIGURE 3. A pawl 162 is shown engaged with a ratchet 163 and as the cam 107 rotates clockwise as seen in FIGURE 3, the lever 150 is driven counterclockwise by the cam 107 until a pin 164 secured to the lever 150 bottoms in the slot 165; as the cam 107 continues to drive the lever 150 and the pin 164 which it carries downwardly, the pawl 162 rotates the ratchet 163 clockwise, thereby rotating the shaft 63 to effect feeding of the record medium R. The slot 165 in the pawl 162 provides a lost-motion connection between the pin 164 and the pawl 162. With this lost-motion connection, the feed wheels 46 and 47 feed the record medium R one line at a time. When the high point of the cam 107 engages the roller 161, the lever 150 is driven counterclockwise to such an extent as to enable a lip 154' of the latch member 155 to latch the latch shoulder 152' as indicated in FIGURES 1 and 2. As the coil 159 is only momentarily energized to initially trip the latch 154, the latch member 155 quickly pivots clockwise, under the urging of the spring 156, into abutment with a face 152', so that latching will be effected as soon as the latch shoulder 152 is moved beneath the lip 154 of the latch member 155 as 'best seen in FIGURE 2. A spring 166 connected to the pawl 162 and to the side plate 22 keeps the pawl 162 in engagement with the ratchet 163, but has insufficient force to over-come the force of the spring 153.

When the latch 154 is tripped by energization of the coil 159, a latch member 170 having a hub 171 secured to the shaft 65 pivots clockwise along with the lever 150. The latch member 170 is normally held against a stop pin 172 secured to the lever 150 by a spring 173. When the lever 170 has pivoted clockwise, a latch member 174 is urged about a pivot 175 by a spring 174' into the path of a face 176. Thus, the latch member 170 is incapable of pivoting counterclockwise as viewed in FIGURE 3 when the cam 107 drives the lever 150 counterclockwise. So long as the latch member 170 remains pivoted clockwise (FIGURE 3), the shaft 65 is in the position shown in FIGURE 6 and the pawl 90 is uncoupled from the feed screw 93. The

latch members

170 and 174 are considered to form a latch generally indicated at 170". A tension spring 177, secured to the side plate 44 and trained about a pulley 178 rotatably mounted on a shaft 179, is connected to a flange 180' of the plate 68 at about the center line of the bushing 74. The spring 177 is used to return the carriage 64 to the start-of-line position. A stud 1 82 adjustably threaded into the body 66 of the carriage 64 strikes the latch member 174 a slight distance forward of the start-of-line position. When the carriage 64 arrives at the start-of-line position, the bushing 74 strikes a rubber bumper 181. The stud 182 pivots the latch member 174 out of the path of the face 176. As the lever 150 has been driven counterclockwise by the time the carriage 64 reaches the start-of-line position, the latch member 170 pivots counterclockwise (FIGURE 1) under the urging of the spring 173 as soon as the latch. member 174 is pivoted clear of the face 176. Counterclockwise pivoting of the latch member 170 rotates the shaft 65 into the position shown in FIGURE and couples the pawl 90 and the feed screw 93.

Operation In operation, assuming that the electric motor 99 is operating at essentially constant speed, and the carriage 64 is at the start-of-line position, the pulley 100 drives the pulley 102 through the belt 101. The clutch 103 is considered to be disengaged and hence the feed screw 93 is not driven. When a start signal is received by the coil 132, the latch member 128 is tripped and the lever 134 rotates counterclockwise as viewed in FIGURE 8, thereby causing the clutch 103 to become engaged. Engagement of the clutch 103 causes the feed screw 93 to feed the carriage away from the start-of-line position until the clutch 103 is disengaged. The feed screw 93 overtravels a minute distance relative to the distance traveled by clutch element 114 until the pawl 142 is in abutment with the tooth 144, thereby disengaging the clutch 103 and preventing any movement of the feed screw 93 until the clutch 103 is again engaged following a subsequent start signal. The feed screw 93 rotates a gear 106 which in turn drives the gear 108. The gear 108 drives the axle 34 and hence the platen 27. As the carriage 64 is traveling away from the start-of-line position and as the platen 27 is rotating, the normally energized coil 77 of the electromagnet 75 is deenergized each time the print hammer 43 is to be driven into printing cooperation with the platen 27 by the spring 84. The interruption of the energization, that is, de-energization of the coil 77, is only long enough to maintain the print hammer 43 in printing cooperation with the platen 27 for the necessary length of time, and thereupon the coil 77 is energized to drive the print hammer 43 out of printing cooperation with the platen 27. When print hammer 43 is in printing cooperation with an element 38 of the rotating platen 27, marking occurs on the record medium R. If letters or figures for example are to be printed, at start pulse for each successive letter or figure is used to energize the coil 132 and hence engage the clutch 103. This simultaneously causes rotation of the feed screw 93 and the platen 27.

Assuming that it is desired to return the carriage 64 to the start-of-line position, the electromagnet 129 (FIG- URE 8) and the electromagnet 158 are simultaneously energized. As soon as the electromagnet 158 is energized the lever 150 and the latch member 170 pivot clockwise as viewed in FIGURE 1. The latch member 170 rotates the shaft 65 from the position shown in FIGURE 5 to the position shown in FIGURE 6, thereby enabling the spring 96 to pivot the pawl into uncoupled position with respect to the feed screw 93. With the carriage 64 uncoupled from the feed screw 93, the spring 177 pulls the carriage 64 to the start-of-line position. As the electromagnet 75 is normally energized, the face 42 is held away from a vane 38 at the printing zone and hence the print hammer does not slide in contact with the record medium R as the carriage 64 is returned to the start-of-line position. Immediately before the carriage 64 reaches the start-ofline position, the stud 182 pivots the latch member 174 clockwise (FIGURE 4) causing unlatching of the latch 170', thereby enabling the spring 173 to pivot the latch member 170 and the shaft 65 counterclockwise into the position indicated in FIGURE 1. Such pivoting of the shaft 65 causes the pawl 90 to be rotated into the position shown in FIGURE 5. The latch member 170 can now pivot into the position shown in FIGURE 1 because the lever and its stop pin 172 have been driven counterclockwise by the cam 1 07 before the latch is unlatched. When the

electromagnets

129 and 158 were energized, the roller 161 was rotated into contact with the low point of the cam 107. The earn 107, being driven as soon as the clutch 103 is engaged, drives the lever 150 downwardly, causing the pawl 162 to rotate the latch 163. Rotation of the ratchet 163 drives the shaft 63 to which the gears 62 and 62' are secured. The

gears

62 and 62 in turn drive respective gears 60 and 61 to drive the feed wheels 46 and 47. When the lever 150 is driven counterclockwise from the position shown in FIGURE 3 to the position in FIGURE 1, the feed wheels 46 and 47 feed the record medium one line space.

The scope of the invention is not to be considered limited to the precise structure depicted in the drawings and described in the foregoing specification. For example the structure for feeding the record medium R is useful with a platen having letters and figures type characters and a print hammer having an appropriate face.

The invention may be embodied in other specific forms Without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being best defined by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

I claim:

1. In a printer: a platen, a carriage mounted for travel lengthwise with respect to said platen, said carriage having printing means cooperable with said platen, a rotatably mounted feed screw, means for releasably coupling said carriage and said feed screw, said coupling means being actuatable between coupled and uncoupled positions, and means for both guiding said carriage and for selectively actuating said coupling means to move between coupled and uncoupled positions, said guiding and actuating means including a member which serves both a guiding function an a selective actuating function.

2. In a printer as defined in claim 1, said guiding and actuating means including a pivotally mounted shaft, latch means for holding said shaft in one position to hold said coupling means in coupled position, means for tripping said latch means to enable said shaft to rotated to provide movement of said coupling means into uncoupled position.

3. In a printer: a platen, a carriage mounted for travel generally lengthwise with respect to said platen, said carriage having printing means cooperable with said platen,

a rotatably mounted feed screw, means for releasably coupling said carriage and said feed screw, said coupling means being actuatable between coupled and uncoupled positions with respect to said feed screw, a shaft having a longitudinal groove into which said coupling means extends, spring means for urging said coupling means into uncoupled position, said shaft being rotatable between a first position in which said coupling means is held in coupled position against the force of said spring means and a second position in which said spring means is free to urge said coupling means into uncoupled position, means for limiting the movement of said coupling means from its coupled position, latch means for holding said shaft in its first position, and means responsive to the tripping of said latch means for rotating said shaft into its second position.

4. In a printer: a platen, a carriage mounted for travel lengthwise with respect to said platen, said carriage having printing means cooperable with said platen, drive means, means for releasably coupling said carriage and said drive means, said coupling means being actuatable between coupled and uncoupled positions, means selectively engaging said drive means for feeding the record medium between said platen and said printing means, a latch for controlling selective engagement of said drive means and said feed means and for controlling movement of said coupling means between coupled and uncoupled positions, an electromagnet for tripping said latch, and means responsive to the tripping of said latch for efiecting movement of said coupling means to its uncoupled position and for enabling engagement of said feed means with said drive means to feed the record medium.

5. In a printer: a platen, a carriage mounted for travel lengthwise with respect to said platen, said carriage having printing means cooperable with said platen, rotatably mounted feed screw means, drive means, a clutch selectively connecting said drive means and said feed screw means, feed wheel means for feeding a record medium between said platen and said printing means, means for establishing a drive connection between said drive means and said platen, and means including a cam driven by said feed screw means for selectively establishing a drive connection between said feed screw means and said feed wheel means.

6. In a printer as defined in claim 5, including an electromagnet, and means responsive to said electromagnet and engageable with said clutch for enabling said clutch to rotate said feed screw means by a predetermined amount each time said electromagnet is operated.

7. In a printer as defined in claim 5, wherein said means for establishing a drive connection between said drive means and said platen includes means drivingly connecting said feed screw means and said platen.

8. In a printer: a platen, a carriage mounted for travel lengthwise with respect to said platen, said carriage having printing means cooperable with said platen, rotatably mounted feed screw means, drive means, a clutch selectively connecting said drive means and said feed screw means, feed wheel means for feeding a record medium between said platen and said printing means, means for establishing a drive connection between said feed screw means and said platen, and means for selectively establishing a drive connection between said feed screw means and said feed wheel means, wherein said selective drive connection establishing means between said feed screw means and said feed wheel means includes a latch and a cam, and an electromagnet for tripping said latch to enable said cam to actuate said feed wheel means, said cam being effective to reset said latch.

9. In a printer: a platen, a carriage mounted for travel lengthwise with respect to said platen, said carriage having printing means cooperable with said platen, rotatably mounted feed screw means, drive means, a clutch selectively connecting said drive means and said feed screw means, feed wheel means for feeding a record medium between said platen and said printing means, means for establishing a drive connection between said feed screw means and said platen, and means for selectively establishing a drive connection between said feed screw means and said feed wheel means; wherein said selective drive connection establishing means between said feed screw means and said feed wheel means includes a cam driven by said feed screw means, a follower movable into and out of engagement with said cam, stepping means operated by said follower, and means for selectively actuating said follower into engagement with said cam to effect stepping of said feed wheel means.

10. In a printer: a platen, a carriage mounted for travel generally lengthwise with respect to said platen, said carriage having printing means cooperable with said platen, a rotatably mounted feed screw, means for releasably coupling said carriage and said feed screw, said coupling means being actuatable between coupled and uncoupled positions, and means for both guiding said carriage and for actuating said coupling means to move between coupled and uncoupled positions, said guiding and actuating means including a pivotally mounted shaft, latch means for holding said shaft in one position to hold said coupling means in coupled position, and means for tripping said latch means to enable said shaft to rotate to provide movement of said coupling means into uncoupled position.

11. In a printer: a platen, a carriage mounted for travel with respect to said platen in forward direction from a start-of-line position and in carriage return direction, said carriage having printing means cooperable with said platen, means for driving said carriage, means for selectively coupling and uncoupling said drive means and said carriage to enable coupling during travel in forward direction and uncoupling during travel in carriage return direction an electromagnet, first latch means re sponsive to operation of said electromagnet for uncoupling said coupling means to enable travel of said carriage in carriage return direction, and second latch means for maintaining said coupling means uncoupled and removed from control of said first latch means until said carriage is returned to start-of-line position, means operated by said drive means for resetting said first latch means, and means operative upon return of said carriage to start-ofline position to trip said second latch means for permitting coupling of said coupling means under control of said first latch means to enable said carriage to be driven in forward direction.

12. In a printer: a platen, a print hammer having a face and an armature, said print hammer being movable between a first position wherein said face is out of printing cooperation with said platen and a second position wherein said face is in printing cooperation with said platen, spring means acting on said print hammer and constituting means for driving said print hammer from said first position to said second position, and an electromagnet cooperable with said armature and constituting the sole means for driving said print hammer from said second position to said first position against the force of said spring means and for holding said print hammer in said first position against the force of said spring means.

13. In a printer as defined in claim 12, wherein said spring means constitutes the sole means for driving said print hammer from said first position to said second position.

14. In a printer as defined in claim 12, wherein said platen includes a plurality of edges with which said face of said print hammer cooperates, and wherein said print hammer is pivotally mounted.

15. In a printer as defined in claim 12, a pivot disposed at one end of said armature for pivotally mounting said print hammer, said electromagnet including a U-shaped core and a coil, said core having a first leg terminating at said one end of said armature and a second leg terminating at the other end of said armature.

References Cited UNITED STATES PATENTS Crowell 10193 Masterson 10193 XR Palmer 197-16 Stutz et a1 10193 Brown et a1. 10193 Hoffmann 10193 Hornauer et a1. 10193 XR Nelson et a1 10193 Scheibeler 10193 XR Schacht 10193 Miller 10193 Yazejihan et a1. 10193 XR Kleinschrnidt et a1. 197144 XR ROBERT E. PULFREY, Primary Examiner.

EDGAR S. BURR, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,429,414 February 25, 1969 Wilburn F. Bradbury It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lines 5 and 27, electromagent", each occurrence, should read electromagnet line 48, "elevationl" should read elevational Colun 3, line 4, "26 should read 36 Column 4, line 37, before "means inse sole line 39, cancel "sole"; same line 39, "into should read out c Column 8, line 65, an" should read and line 70, "rotated" should read rotate Signed and sealed this 24th day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR

Commissioner of Patents Edward M. Fletcher, J 1'.

Attesting Officer