US 3572489 A
Description (OCR text may contain errors)
United States Patent  Inventor John 0. Schaefer Lexington, Ky.
 Appl. No. 774,281
 Filed Nov. 8, 1968  Patented Mar. 30,1971
 Assignee International Business Machines Corporation Armonk, N.Y.
 TYPEWRITER WITH EXTENDED WRITING LINE 4 Claims, 2 Drawing Figs.
Primary Examiner-Ernest T. Wright, Jr. Attorneys-Hanifin and J avin and E. Ronald Coffman ABSTRACT: The writing line of a moving print element typewriter is extended beyond the typewriter side frame by employing a long paper carriage and effecting conjoint opposite direction movement of the paper carriage of a print element carrier. Absolute movement of the paper carriage and the print element carrier is thus less in each case than the length of the writing line. A mechanical interconnection is employed to allow control over both movements to be obtained by controlling the movement of the print element carrier. Movement of the print position between adjacent letters is accomplished by moving the print element two-thirds of a letter space to the right and simultaneously moving the paper onethird of a letter space to the left to minimize the effective inertial loads on the system.
Patented March 30, 1971 1 3,572,489
JOHN 0. SCHAEFER 6Y8 PM W ATTORNEY.
l TYEEWMTEE WlTlil EXTENDED WRITING MNE DISCLOSURE OF THE INVENTION CROSS REFERENCE Reference is made to application Ser. No. 774,276 entitled Typewriter With Extended Writing Line, filed simultaneously herewith by W. A. l-leidt, L. E. Palmer and J. O. Schaefer, which discloses a typewriter having a movable paper carriage and a movable print element which are controlled to achieve an extended writing line.
Conventional typewriters have employed a moving paper carriage for advancement of a single character printing along a writing line. Also, existing typewriters, such as that shown in U.S. Pat. No. 2,879,876, employ a stationary'paper holding device and an incrementally moving print element carrier for letter feed advancing.
Both forms of known typewriters have practical limits to extension of their writing line. In the moving paper carriage machine, the writing line is limited by the ability to control rapid feed of a large mass and the ability to accept a large overhang space requirement for the machine. In the fixed paper machine, the writing line is limited bythe practical width of the entire machine which must exceed that of the writing line. in both forms of existing machines, extension of the writing line increases the difficulty of maintaining proper control over letter feeding by the usual main spring device which is required to operate uniformly over a larger effective stroke or distance.'
My invention overcomes the limitations and difficulties inherent in existing machines by combining both forms of letter feed advance in a unique manner. A machine constructed in accordance with my invention will occupy less desk space for a given writing line than a machine having only a movable paper carriage. in addition, my typewriter reduces the speed and distance over which the large mass of the paper carriage is required to be moved and thereby has eliminated the necessity of specific ancillary mechanism such as air cylinders, for carriage deceleration.
A novel interconnection between the paper carriage and the print element carrier in my invention allows the total horizontal control over the printing position to be achieved by mechanisms essentially like those currently employed in the IBM Selectric" typewriter manufactured and sold by International Business Machines Corporation, Armonk, New York and described in IBM Customer Engineering Instruction Manual Form EN 24 1 5032 1 published Apr., 1964 by International Business Machines Corporation, Armonk, New York.
While it has in the past been proposed to build typewriters with movable print elements and paper carriages for the purposes of achieving variable spacing as shown in U.S. Pat. No. 470,704, or for the purpose of prhviding changeable type faces as shown in U.S. Pat. No. 2,ll78,037, neither of these prior uses of combined moving paper and moving print mechanisms provide or otherwise teach any mechanism by which the writing line of a typewriter can be effectively extended as herein disclosed.
OBJECTIVE It has been an objective of this invention to effectively extend the writing line of a single element-type typewriter and without correspondingly extending the typewriter size and without excessively adding to the machine complexity.
MECHANISM CONCEPTS Aforesaid copending application Ser No. 774,276 discloses the basic concept of adding together the travel of a letter feeding print element to the travel of a paper holding carriage to provide an efficiently extended writing line. My invention employs this basic concept to particular advantage by interconnecting the print element carrier and the paper carriage for conjoint movement in opposite directions whereby all displacement of the printing position is achieved by the combined movement of both the print element and the paper carriage. By providing this interconnection, l have retained control over the printing position by the normal letter feed, backspace, tabulation, and carrier return mechanisms thus minimizing the complexity of the overall final machine.
Also, by dividing the motion of the printing position between the relatively small print element carrier and the relatively large paper carriage, the velocity of each is reduced with the result that the motion of the large mass paper carriage can be controlled without such expedients as air cylinder decelerators usually employed in large powered typewriters. l have taken particular advantage of this motion division in a preferred embodiment of my invention by dividing the motion unequally so that the print element carrier moves twice as far and twice as fast as the large mass paper carriage. I have also discovered that by the use of flexible steel cables to provide the novel interconnection between the paper carriage and the print element carrier there is inherently provided sufficient intemal resiliency to minimize shock due to abrupt arresting of the moving system.
These and other objects, concepts and advantages of my invention will be more completely understood from the following detailed description of a preferred illustrative embodiment of my invention wherein reference is made to the accompanying drawing, of which:
FIG. 1 is a perspective view of a typewriter having an extended writing line obtained through use of my invention; and
FIG. 2 is an exploded perspective view of the principal active elements of my invention showing their structural details and interrelationships.
Referring now more specifically to the drawing, in FIG. 1 there is shown a typewriter 10 having a frame 11, character defining means, print head or type element 20, and paper holding means such as a platen 30. The type element 20 is operated by mechanisms not shown herein but fully disclosed in U.S. Pat. No. 2,919,002. As disclosed in U.S. Pat. No. 2,919,002, the type element 20 is supported on a carrier 21 which in turn is slidably mounted for lateral movement along a rectilinear path 22 on parallel tracks provided by a rotatable shaft 23 and a letter feed control escapement rack 24.
Platen 30 is mounted on a carriage 31 that is supported in a pair of tracks or rails 32 by interposed roller bearings 33 of known construction for lateral movement along a rectilinear path 34 parallel to path 22. Type element 20 and platen 30 define therebetween a character print position 12, which by conjoint, oppositely directed movement of the type element 20 and platen 30 along their respective paths 22 and 34 defines a writing line 13. To obtain the conjoint movement, the carrier 21 is interconnected with carriage 31 by motion transmitting means such as a flexible braided steel cable 40. Cable 40 is connected by eye-clevis 41 to an upstanding stud 25 on the carrier 21. Frame mounted idler pulleys 42 and 43 guide cable 40 to motion-transforming block and tackle pulley 44 mounted on a stub shaft 35 carried by the platen carriage 31. The cable 40 is anchored at its other end to the frame ll by an eye-clevis 45 and an anchor bracket 14. The interconnection provided by cable 40 causes the platen carriage 3i and the print element carrier 21 to move conjointly in opposite directions and in a motion ratio of 1 to 2. More specifically, if carrier 21 is displaced 1 inch to the left in FIG. 2, cable 40 and pulley 44 will cause carriage 31 to move one-half inch to the right. Print position 12 will effectively be displaced atotal of 1 inches.
Carrier 21 and carriage 31 are moved in the forward or letter feeding direction by means of a clock spring 51 mounted on the frame 11 by a cage or mounting bracket 52. Clock spring 51 is continuously effective to impositively urge a shaft 53 counterclockwise. Shaft 53 is mounted in frame 111 by bearing 54 and carries a capstan 55 for winding a flexible braided steel cord or cable so that provides a one-way driver connection to the carriage 31. Cable 60 is tracked over idler pulleys 61, 62, and 63, tensioning idler pulley 64, and motiontransforming pulley 65 and is anchored at its free end to the frame 11 by an eye-clevis 66 on a frame bracket 15. Motiontransforming pulley 65 is rotatably supported on a stub shaft 36 carried by the platen carrier 31. Accordingly, counterclockwise rotation of shaft 53 by clock 51 winds cord 60 onto capstan 55 and draws motion-transforming pulley 65 and the platen carriage 31 leftwardly. Leftward movement of platen carriage 31 moves motion-transforming pulley 44 leftwardly to draw the type element carrier 21 rightwardly through interconnecting cable 40.
Printing position 12 is moved in the reverse or line return direction through a normally disengaged spring clutch 56 that is selectively operable by a control shoe 57 to connect a source of continuous rotating motion from shaft 58 to drive the shaft 53 in a clockwise direction as more completely described in U.S. Pat. No. 2,909,935, A capstan 59 is secured to shaft 53 for winding a flexible braided steel cord or cable 70 that provides a one-way driving connection to the carrier 21. Cable 70 is tracked over idler pulleys 71, 72 and 73 and is connected at its free end to the carrier 21 through an eye-clevis 74 that engages a carrier mounted hook 26. Engagement of spring clutch 56 by clockwise rotation of shoe 57 causes clockwise rotation of shaft 53 to wind cord 70 on capstan 59 and draw carrier 21 leftwardly. Leftward motion of carrier 21 acts through interconnecting cable 40 to draw platen carriage 31 rightwardly. Clockwise motion of shaft 53 also winds the clock spring 51 to store energy therein.
lt can be seen that winding of cord on either capstan 55 or 59 is simultaneously accompanied by an unwinding of cordfrom the other capstan. Tension in cords 40, 60 and- 70 is maintained by springs 67 which are connected to the frame 11 and to a slidably mounted pin shaft 68 which supports tensioning pulley 64 to urge pulley 64 leftwardly and thereby take up slack in the cable system.
Lateral control of the printing position 12 is fundamentally accomplished through the escapement rack 24 which is mounted on the frame 11 by screws 16 and is provided with a series of holding teeth 81 each of which individually define a specific horizontal letter space printing position 12. The carrier 21 includes a rearward extending bracket portion 82 that supports a letter feed escapement pawl 83 by a fixed pin or stud 84 that is received in an elongated pawl slot 85. The position of pawl 83 thus reflects the position of carrier 21. A spring 86 urges the pawl 83 rightwardly and forwardly into an engagement with the rack teeth 81. Normally, clock spring 51 urges carrier 21 rightwardly against the holding action of pawl 33. The pawl 83 is further provided with a tab portion 87 by which the pawl 83 can be lifted from the rack teeth 81. When so lifted, pawl 83 will be moved forwardly by a pring 86 as permitted by slot 85 and will fall into the next succeeding rack tooth 81. The clock spring 51 will thus be freed to move the carriage 31 leftwardly and the carrier 21 rightwardly by one letter space until pin 84 again comes to rest at the rightward edge of slot 85. Mechanism for operating the tab 87 is completely disclosed in U.S. Pat. No. 3,126,998.
As mentioned above, each tooth 81 of the rack 24 defines a discrete horizontal location of printing position 12. The teeth 81 are not, however, spaced horizontally apart by a distance equal to the distance between adjacent print positions 12, since the total spacing includes not only motion of the carrier 21 which is controlled by the rack 24, but also the motion of platen carriage 31 which is one-half of the carrier 21. Accordingly, if it is desired to employ l2-pitch type, i.e., type sized to print 12 characters per inch, rack 24 will be constructed with 12 teeth per two-thirds inch or l8 teeth per inch. Each operation of escapement pawl 83 thus will allow the carrier 21 to move rightwardly by two-thirds of a letter space increment and through cord 40 and motion transformer 44 will allow platen carriage 31 to move leftwardly the remaining one-third of the spacing increment. It can be seen that other print position controls, such as tabulation, backspace, and carrier return will function in a similar manner to position the carrier 21 and platen carriage 31 by acting directly on and in conjunction with the type element carrier 21.
It is to be understood that various structural modification can be made through the embodiment shown while retaining the benefits of my invention. Specifically, the control of letter feed position can be applied to the platen carriage 31 instead of to the carrier 21, the motion transmitting cord system disclosed can be replaced by the equivalent gearing, and other forms of typing mechanism can be substituted for the type element 20 shown herein. Having thus described and illustrated the concepts of my invention, I define the subject matter sought to be patented by the following claims:
1. A typewriter having a frame, character defining means, and paper holding means cooperable therewith to mutually define a printing position; first track means carried by said frame and supporting said character defining means for movement along a first rectilinear path, and second track means carried by said frame adjacent said first track means supporting said paper holding means for movement along a second rectilinear path that is parallel to said first path, whereby said printing position can be displaced to define a writing line and wherein the improvement comprises:
motion transmitting means interconnecting said character defining means and said paper holding means comprising means for transmitting motion therebetween for effecting conjoint, oppositely directed movement of said character defining means and said paper holding means along their respective paths;
a shaft rotatably mounted on said frame, means for selectively driving said shaft in either rotational direction;
a first one-way power transmitting connection between said shaft and said character defining means for transmitting displacement force thereto upon rotation of said shaft in one direction; and
a second one-way power transmitting connection between said shaft and said paper holding means for transmitting displacement force thereto upon rotation of said shaft in the other direction.
2. A typewriter having a frame, relatively low mass character defining means, and relatively high mass paper holding means cooperable therewith to mutually define a printing position; first track means carried by said frame and supporting said character defining means for movement along a first rectilinear path, and second track means carried by said frame adjacent said first track means supporting said paper holding means for movement along a second rectilinear path that is parallel to said first path, whereby said printing position can be displaced to define a writing line and wherein the improvement comprises:
motion transmitting means interconnecting said character defining means and said paper holding means for conjoint, oppositely directed movement along their respective paths, said motion transmitting means including motion transforming means for causing relatively greater movement of said character defining means than said paper holding means; and
means for moving said character defining means and said paper holding means relative to said writing line.
3. A typewriter as defined in claim 2 wherein said means for moving said character defining means and said paper holding means comprises:
a shaft rotatably mounted on said frame;
means for selectively driving said shaft in either rotational direction;
a first one-way power tr transmitting connection between said shaft and said character defining means for transmitting displacement force thereto upon rotation of said shaft in one direction; and
a second one-way power transmitting connection between said shaft and said paper holding means for transmitting force thereto upon rotation of said shaft in the other direction.
6 relationship with said character defining means and selectively engageable with said rack means to retain said character defining means in any of a plurality of spaced positions along said r rack means relative to said frame.