US 3913722 A
A high speed printer has a drum with a cylindrical wall of resilient material. On the cylindrical wall, a series of type formations are arranged in a helical path about the external periphery. A feeding mechanism is provided for operating a printing medium past the periphery of the drum, in contiguity with the type formations. Driving means is provided for rotating the drum about the axis of the helical path and at the same time translating the drum longitudinally along the axis so that each type formation passes in substantially continuous succession past each of a plurality of spaced printing positions on the medium. A hammer element is located substantially inside of the drum. This hammer element is movable by the driving means together with the drum when the latter is translated longitudinally along its axis. When the hammer element is selectively actuated against the inside of the cylindrical wall of the drum behind a selected type element, resilient flexing of the cylindrical wall selectively imprints characters on the medium.
Description (OCR text may contain errors)
United States Patent 1191 Bowdle et al.
[4 Oct. 21, 1975 DRUM PRINTER  Inventors: Raymond Ralph Bowdle, Morgan Hill; Robert Junior Laybourn, San Jose, both of Calif.
 Assignee: International Business Machines Corporation, Armonk, NY.
 Filed: Aug. 28, 1972  Appl. No.: 284,297
 Published under the Trial Voluntary Protest Program on January 28, 1975 as document no. B 284,297.
 US. Cl. 197/54; 101/93.16; 101/93.23;
101/109  Int. Cl. B41J l/34  Field of Search 101/93,111, 109, 110; 197/53, 55, 18, 49, 1 R, 54
 References Cited UNITED STATES PATENTS 2,843,243 7/1958 Masterson 197/19 2,958,568 11/1960 Hagelbarger... 197/1 R 3,295,652 1/1967 Sasaki 197/53 3,326,346 6/1967 Sasaki 101/111 X 3,378,127 4/1968 Clary et al. 197/53 3,384,216 5/1968 Thayer 197/53 3,408,930 11/1968 Chamness et a1 101/93 3,415,184 12/1968 Perucca 10l/93 C 3,589,494 6/1971 Gloess 197/18 3,651,914 3/1972 Locke 197/49 3,651,916 3/1972 Becchi 101/93 C 3,717,234 2/1973 Koller 197/53 FOREIGN PATENTS OR APPLICATIONS 1,239,360 7/1971 United Kingdom Primary ExaminerRobert E. Bagwill Assistant ExaminerPaul J. Hirsch Attorney, Agent, or Firm-Shelley M. Beckstrand  ABSTRACT A high speed printer has a drum with a cylindrical wall of resilient material. On the cylindrical wall, a series of type formations are arranged in a helical path about the external periphery. A feeding mechanism is provided for operating a printing medium past the periphery of the drum, in contiguity with the type forma tions. Driving means is provided for rotating the drum about the axis of the helical path and at the same time translating the drum longitudinally along the axis so that each type formation passes in substantially continuous succession past each of a plurality of spaced printing positions on the medium. A hammer element is located substantially inside of the drum. This hammer element is movable by the driving means together with the drum when the latter is translated longitudinally along its axis. When the hammer element is selectively actuated against the inside of the cylindrical wall of the drum behind a selected type element, resilient flexing of the cylindrical wall selectively imprints characters on the medium.
5 Claims, 7 Drawing Figures .U.S. Patent Oct. 21, 1975 -Sheet10f2 3,913,722
US. Patent Oct.21, 1975 Sheet2of2 3,913,722
PTAPE DRUM PRINTER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a novel and improved drum printer for recording characters on a medium.
2. Description of the Prior Art A typical type of prior art drum printer is structured so that a formation of type elements is arranged in a helical path on the external periphery of the drum and a striking member or hammer acts to compress the medium between a face of the hammer and the type elements on the external drum surface. The drum is commonly driven in such a manner that it rotates about its axis and at the same time also translates longitudinally along the axis so that each type element passes each of the plurality of spaced printing positions of the medium, in substantially continuous succession.
Efforts have been made in recent years to provide a lowcost and compact type of drum printer. For example, drum printers have been provided with radially movable types that are struck by a hammer located inside of a drum. However, these devices have been considered somewhat bulky, unreliable, and also uneconomical in assembly and material costs. Accordingly, it has been found desirable to provide a low-cost, compact and improved drum printer which overcomes the disadvantages of such known prior art techniques.
SUMMARY OF THE INVENTION An important object of this invention is to provide a novel and improved drum printer structured so that it may be very small in size, yet low in cost.
Another object of this invention is to provide an improved drum printer which uses a drum of resilient material.
A further object of our invention is to provide a drum printer having a resilient cylindrical wall for supporting type formations, and a hammer arranged inside of the drum for front printing.
Still another object of this invention is to provide an improved drum printer wherein the type font is arranged on the drum in a spiral fashion and the drum is capable of continuously scanning a page without escapement.
In carrying out this invention in one form thereof, there is provided a high-speed drum printer which includes a cup-shaped drum having a cylindrical wall of resilient material. On the external surface of the cylindrical wall of the drum there is arranged a series of type formations. This series is disposed in a helical path on the periphery of the cylindrical wall. Mechanism is provided for feeding the recording medium past the periphery of the cylindrical wall. Driving means is included for continuously rotating the drum about the axis of the helical path and at the same time continuously translating the drum longitudinally along the axis so that each type element passes a plurality of spaced printing positions on the medium, in continuous succession.
With this arrangement, a pivoted hammer is located with its striking surface inside of the drum. This hammer is supported on a carriage which also rotatably supports the drum so that the hammer may move longitudinally with the drum when the drum is translating longitudinally along its axis. A hammer actuating mechanism is provided for selectively operating the striking surface of the hammer against the inside surface of the cylindrical wall behind a selected type element when a selected type element passes one of the printing positions. The impact of the actuating surface of the hammer upon the inside surface of the resilient cylindrical wall, causes resilient flexing of the drum wall against the medium to selectively imprint characters thereon. Such a structure allows convenient front printing in conjunction with a drum printer by placement of the hammer actuator inside the cavity of the drum. The overall drum printer is both compact and effective in operation.
BRIEF DESCRIPTION OF DRAWINGS The foregoing and other objects, features and advantages of this invention will be apparent from the following description of the drawings inwhich:
FIG. 1 is a perspective view of a drum printer embodying one form of our invention;
FIG. 2 is a left end view of the printer of FIG. 1, with the motor, side plate and selective driving mechanism removedto more clearly show the paper feed mechanism, carrier, drum interior, and hammer structures;
FIG. 3 is a fragmentary rear view showing the hammer actuating mechanism and the mode of striking the flexible drum wall;
FIGS. 4 and 5 show fragments of the cylindrical wall and-type formations thereon to illustrate by comparison the flexure of a formation in response to its actuation by the hammer;
FIG. 6 shows a modification of the drum and hammer arrangement for the drum printer of FIG. l,which provides two hammers disposed inside of the resilient drum wall; and
FIG. 7 illustrates by means of a fragmentary perspective view, the hammer, its supporting structure, and the associated hammer actuating mechanism.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Referring now to FIG. 1, there is shown a drum printer 11 for recording characters on paper 13 carried by a feed roll 15. The general arrangement of the drum printer 11 includes a slidable carriage 17 which supports a rotatable and slidable drum 19, together with a printing hammer 2]; a selective driving mechanism 23 for operating the drum l9 and hammer 21 in one direction (i.e., to the right, viewing FIG. 1) across the paper 13; a return mechanism 25 for bringing the drum and hammer back to their starting position on the left side of a page after each line has been printed; and a paper incrementing mechanism 27 for vertically spacing automatically from one to the next line after each line of print has been completed.
The selective driving mechanism 23 includes a motor 29 having its output wheel 31 coupled to an emitter wheel 33 by means of driving belt 35. The emitter wheel 33 includes peripheral teeth 37 which correspond in angular relationship to predetermined type characters or elements 39 located on the flexible cylindrical wall 41 of drum 19. More particularly, the emitter 43 preselects the desired tooth 37 of the emitter wheel 33 for each printing position of a line to determine which printing character 39 should be imprinted thereon.
The emitter wheel 33 is supported by means of a shaft 45 that has one of its ends rotatably trunnioned in one side plate 47. The other end 49 of the shaft 45 is rotatably trunnioned in the other side plate 51.
Shaft 45 is threaded with an acme thread 53 having a pitch of threads per inch. The threads 53 of the shaft 45 are also interrupted during each turn by a keyway slot 55 which runs longitudinally and axially from one end to the other of the peripheral surface of the shaft. Directly underneath and parallel to the driving shaft 45, there is located a first guiding shaft 57, which has one of its ends secured to side plate 47 and the other end secured to side plate 51.
The slidable carriage 17 is structured so that it includes a generally U-shaped body portion 59 having two upwardly extensive arms. 61 and 63 connected to a bight portion 65. Arm 61 has a lower cylindrical bore 67 for slidable bearing engagement with, the first guide shaft 57, and an upper cylindrical bore 69 for receiving thedrive shaft 45 therethroughpThe other arm 63 includes a lower cylindrical bore 71 for providing bearing cooperation with the first guiding shaft 57, and an upper cylindrical bore 73 for receiving the drive shaft 45 therethrough.
From viewing FIG. 1 it will be noted that an additional guide shaft 75 is extended in parallel relationship to the first guiding shaft 57, between side plates 47 and 51. Shaft 75 receives a lateral bearing arm 77 which extends frontwise (viewing FIG. 1) from the bight portion 65, to provide a partially cylindrical bearing channel 79 for stabilizing the sliding movement of carriage 17.
From viewing FIG. 1, it will be further noted that there is secured to the frontal face of upright 61 of body portion 59, a small electromagnet 81. The electromagnet 81 includes coil 83 which surrounds one arm of a U-shaped core member 85, and a pivoted magnetizable arm 87 which is attracted by the magnet 81 upon energization of the coil 83. Attached to the arm 87 is a small shaft 89 that is rotatably supported in a pair of opposed apertures 91 located at the top of upright arm 61. The shaft 89 has secured thereto a tongue 93 which is pivotally movable with both shaft 89 as well as its attached magnetizable arm 87. Tongue 93 is normally acted upon by a spring 95 so that its free end 97 is disposed upwardly and away from the threads 53 of shaft 45. The free end 97 of tongue 93 has integrally formed thereon a series of arcuate projections 99. The projections 99 serve as a half nut in cooperation with the thread 53 of shaft 45. Thus, when the coil 83 of the electromagnet 81. is energized, magnetic arm 87 of the electromagnet is attracted toward the coil so that tongue 93 pivots in opposition to its normal spring biasing force until projections 99 of the tongue are in threaded cooperation with the driving shaft 45. Then, upon rotation of the shaft 45 about its bearings, carriage 1.7 is gradually driven in a longitudinal direction from left to right (viewing FIG. 1) by means of the threaded engagement of the tongue 93 with shaft 45.
On upright arm 63 of carriage body portion 59, there is disposed a pivoted coupler 101 arranged for rotation on pivot pin 103, to lock the drum 19 at the desired longitudinal position on carriage 17. Coupler 101 has an arcuate surface 105 which engages an annular recess 107 formed in hub 109 of the drum 19. In addition, viewing FIG. 1, the drum 19 includes the aforemen tioned flexible cylindrical wall 41. Wall 41 has an annular internal groove which snaps into cooperation with an apertured metal disk 113 (FIG. 2). The disk 113 is preferably integral with the hub 109. It is considered advantageous that the annular groove of the drum .119
be located at the axial end of the drum located away from the electromagnet 81., so that the drum 19 essen= tially provides a cup-shaped recess for receiving hammer 21. Hub 113 has a key 114 (FIG. 2) formed thereon for drivably coupling drum 19 to keyway slot 55 of drive shaft 45.
The type elements 39 are arranged in spiral fashion,
on the external periphery of the flexible cylindrical wall 41 with the same pitch as the thread 53 ofshaft 45, in a manner well known in the art, so that upon each rotation of drum l9, withthe thread (projections 99) of tongue 93 enmeshed with thread 53 of shaft 45, the
type elements 39 on cylindrical wall 41 all pass one" printing position relative to the paper 13.
Turning now to an importantaspect of the present invention which helps achieve a low-cost, compact and efficient printing mechanism, it will be noted that on the side ofU-shaped body portion 59 opposite the lateral bearing arm 77 (viewing FIG. 1), there is located a hammer actuating mechanism 115 (see FIG. 3). Ac-
tuating mechanism 115 involves a core member .117
having an upper arm 1 19 that extends through coil 121.
The core member 117 is secured to the U-shaped body portion 59 by means of a non-magnetic plate 123 and screws 125. Plate 123 helps to support a magnetizable actuator 127 which is pivoted thereto by pin 129. The
operating finger 131 of actuator .127 engages the ing FIG. 7, the corner area 139 of hammer 21 has a 2 suitable aperture (not shown) to receive a bearing pin 140 which extends through two opposite horizontally extensivesides of the upright section .137 and is secured thereto. Hammer 21 is rotatable aboutits bear- I ing pin so that its actuating head 141 impacts on the inside surface of the cylindrical wall 41 opposite the type 39 (FIG/1) to compress these element into engage.- ment with the printing medium (e.g., paper 13).
In FIGS. 4 and 5 there are shown two views to illustrate the manner in which the actuating head 141. of
hammer 21 engages the inside surface of cylindrical wall 41 of drum 19. Thus, FIG. 4 shows theactuating head 141 in its inactive position, in radial alignment with one of the printing characters 39. For this position, the head 141 is disposed radially inwardly and spaced apart from the aligned printing character 39.. FIG. 5 showsthe head 141 after it has engaged theresilient wall behind the aligned printing character 39. It
will be noted that the external or actuating face of the character 39, is thus thrust radially outwardly from the axis of rotation of the drum 19 for engagement with the,
printing medium or a suitable carbonized ribbon adjacent to such a medium.
It will be seen that by securing the hammer actuating mechanism 115 to body portion 59 of the slidable carriage 17, and locating the hammer actuating head .141
inside of the recess of the flexible drum 19, the hammer 1 21 translates longitudinally with the drum. and is always in the proper printing position. Such an arrangement is very compact and leads to significant advantages in front printing. 1
The pivoted coupler 101 engages annular recess 107 of hub 109 of the drum 19' to normally retain it into coupled engagement with the slidable carriae 17. When it is desired to remove drum 19 for servicing, the arcuate portion 105 of the pivoted coupler is moved out of engagement with the circular recess 107 to disengage the drum 19. The drum may then be slid longitudinally along shaft 45 for appropriate removal from the printer 11, such as by first detaching side plate 51.
For returning the slidable carriage 17 to the left side of the page after the completion of each printed line,
a suitable return mechanism 25 has been provided. For the embodiment set forth in FIG. 1, the return mechanism 25 comprises a cord 143 which is secured to carriage body 59 by means of screw 144. Cord 143is extended around peripheral sections of the rotatable pully wheels 145 and 147. The end of the cord 143 opposite screw 144 is biased by spring 149, which is connected by link 150 to the side plate 51, so that the carriage 17 is normally urged to its left or return position. Thus, when the slidable carriage 17 has reached the right side of the page or any position to the right of its normal starting position (on the left side of the page), spring 149 exerts a pulling type biasing force on cord 143 which causes the carriage to return'to its initial starting position, to the left of the page.
Another important aspect of the present invention concerns the provision of a novel and improved paper incrementing mechanism 27 in the drum printer 11 (see FIG. 2). Essentially, the mechanism 27 includes an elongated actuator 151, a connecting rod 153 adjustably linked to the actuator 151 by a threaded nut 155, a rotatable rocker arm 157 coupled to the rod 153 at its bifurcated end 153a, a biasing spring 159 for normally urging the rocker arm 157 in a clockwise direction of rotation (viewing FIG. 2), and a ratchet wheel 161 drivably associated with a pawl 163, pivotally attached to the rocker arm 157 by pin 164.
The elongated actuator 151 has a ball-shaped end 165 which is acted upon by shoulder 167 located on the bottom of the slidable carriage 17. The supported end 169 of actuator 151 is bent over twice to provide a pair of arms 169a having aligned bearing apertures 17] (FIG. 1). The bearing apertures 171 receive a cylindrical pin 173 secured to a suitable support 174 so that the actuator 151 is rotatable about a vertical axis with the ball-shaped end 165 movable in the same general direction as the longitudinal axis of shaft 45.
Near the shorter end of the supporting section for actuator 151, there is formed an extension 175 that is pivotally connected to the threaded nut 155. Nut 155 is in adjustable engagement with a threaded end of connecting rod 153. The other end 153a of the connecting rod 153 is pivotally supported by means of a shaft 177 having its longitudinal axis in a horizontal direction. Shaft 177 also pivotally supports the ratchet wheel 161. The bottom end 179 of rocker arm 157 is connected to one end of the spring 159. The other end of the spring 159 is secured to the support 174. Spring 159 acts upon. the rocker arm 157 to bias it in a clockwise direction of rotation (viewing FIG. 2). The pawl 163 is pivotally linked to the other and opposite end of the rocker arm 157 from the end 179. Pawl 163 is gravity operated so that whenever the ratchet wheel rotates in a counterclockwise direction the driving end 183 of pawl 163 first allows the ratchet wheel 161 to rotate and then seats its sharp end in the next consecutive tooth. The shaft 177 is elongated and connected to a series of spaced apart driving spools (not shown) to drive the medium 13 and thereby progress flexible material therefrom one line space for each tooth of rotation of the ratchet wheel.
Another important advantage of the present invention resides in the fact that modular feed rolls may be provided with the printer 11. For example, in addition to handlingpaper material such as that shown in feed,
roll 15 for FIG. 1, the printing device 11 may also be interchangeably used for print cards suitably fed toward the rear or drum 19. I
It will now therefore be seen that we have provided a new and improved drum printer which readily lends itself to mass production manufacture. By placement of the hammer actuating surface inside of a flexible drum surface, a compact and low-cost arrangement is achieved for front printing on either paper or cards. One of the significant advantages residing in such an approach isthat it is no longer necessary to actuate a print hammer through a variable thickness document (such as a passport). The particular type of printer embodying our invention may be readily and beneficially used for a low-cost computer terminal.
Such a printer may also be utilized with two or more hammers advantageously located inside of,the drum. An example of this particular type of printer is shown in FIG. 6. Here, the structure of drum 19 and its flexible cylindrical wall 41 are essentially the same as for the main embodiment shown in FIG. 2. However, the slidable carriage 217 is different, in that it is guided by first and second shafts 257 and 275 which are in vertical alignment instead of horizontal alignment; The shafts 257 and 275 are in slidable cooperation with apertures 267 and 279, respectively, the latter of which resembles an open ended slot like slot 79 of the FIG. 1 embodiment.
To enable the alternative embodiment of FIG. 6 to support two hammers 21 that are diametrically opposed and located inside of drum 19, two separate and distinct hammer actuating mechanisms 215 are provided, which are suitably supported and carried by the carriage 217. For this particular modification of the original embodiment, each of the two diametrically opposed hammers might be operable by separate and discrete actuating mechanisms so that one hammer might be printing on paper while the other is printing at the same time on ajournal or on tape, as shown by the dash lines of FIG. 6.
While in accordance with the Patent Statutes, we have described what at present are considered to be the preferred aspects of this invention, it will be obvious to those skilled in the art that various changes or modifications may be made therein without departing from the present invention.
What we claim is:
l. A high speed printer for recording characters on a medium comprising:
a rotatable drum having a cylindrical wall of resilient material,
a series of type formations disposed in a helical path on the periphery of said cylindrical wall,
means for feeding the medium past the periphery of said cylindrical wall,
driving means for rotating said drum about the axis of said helical path and at the same time translating said drum longitudinally along said axis so that each type formation will pass in substantially continuous succession past each of a plurality of spacedprinting positions on the medium,
a striking member located at least partially inside of said drum and movable by said driving means together with said drum in a longitudinal direction when said drum is translating longitudinally along said axis, and
means for selectively actuating said striking member against the inside surface of said cylindrical wall behind a selected type formation whenever a selected type formation passes one of said printing positions, thereby causing resilient flection of said drum wall to selectively imprint characters on said medium;
said driving means comprising:
an elongated drive shaft rotatably driven by said motor,
said shaft having a series of threads formed on its periphery and a longitudinal slot formed on the periphery of said shaft in parallel relationship with the axis of rotation of said shaft,
therein for receiving said drive shaft,
pivoted and threaded element supported by said carriage and selectively cooperable with the threads on the periphery of the drive shaft for translating said carriage along the longitudinal axis of the drive shaft when said shaft is rotatably driven by said motor and the pivoted element is in threaded engagement with said drive shaft,
said drum including in addition to its cylindrical wall a hub, and
slidable carriage having at least one bore formed said hub having a key formed thereon for cooperation with the longitudinal slot of said shaft, so that the drum is rotatably driven by the shaft upon rotation thereof by the motor. 2. The high speedprinter of claim 1 wherein said carriage further supports a pivoted latch for couplingsaiddrum to said carriage.
3. The high speed printer of claim 2 wherein the carriage further includes two guiding channels, each of said guiding channels receiving a relatively fixed associ ated guiding shaft for guiding and stabilizing the carriage during driven movement thereof in response to energization of said motor.
4. The high speed printer of claim 3 wherein a spring biased cord is operable between one side of said carriage and a fixed support to return the printing carriage to its starting position after a page has been printed 5. The high speed printer of claim 4 wherein theselective actuating mechanism for the striking member includes a pivoted arm supported by the carriage, said arm having a slot therein for supporting saidstriking printing function, the other end of said striking member being positioned on the carriage for selective actuation by a magnetizable member supported by said carriage.