IL28608A - Dual motion typewriter - Google Patents

Description

Dual motion typewriter I.l.M. (ISRAEL)LTD. and DAN OLAMI IBM (ISRAEL) LIMITED Inventor: Dan Olami DUAL MOTION TYPEWRITER The present invention relates to improvements in typewriters and aims at making them convertible for writing from left to right as » well as from right to left.

Most of the typewriters are designed to write from left to right, which is the usual direction for languages written with Latin characters, but there are other languages, e.g. Arabic or Hebrew, which are^written from right to left. Accordingly, typewriters have been proposed that use the mechanism of the Latin version of typewriters but in which a I r SZ 9-67-004 - 1 - number of parts, particularly those responsible for the reverse motion of the carriage, take the form of mirror images of the parts effecting a left to right motion.

Other proposals were directed to modifications in the draw band mechanism, some suggesting the alternate attachment of the draw band to one or the other end of the carriage depending on the desired direction of typing, some suggesting the use of an auxiliary intermediary pinion interposed between the pinion of the escapement wheel and the rack.

Typewriters with mechanisms outlined above in general terms have been described in Israel patent No. 1110 where a reversion mechanism comprises a carriage draw band connectable to one or the other end of the carriage. In addition, the direction of rotation of the escapement wheel is reversible either by inverting the rotation of the wheel itself or by interposing an intermediary escapement pinion between the usual pinion rigidly connected to the escapement wheel and the rack affixed to the carriage. The present invention does not make use of change of draw band connection nor does it have provision for changing the direction of rotation of an escapement wheel.

Israel patent No. 1181 is an improvement over patent Ho. 1110 in that it discloses two spring drums turning in opposite directions and cooperating with two draw bands, or one endless draw band, means being provided for alternatively arresting one of the drums. The invention to be described below does not require the provision of two spring drums and two draw bands or one endless band. Δ modification of the above-mentioned shown in Israel patent No. 2771» where there is only one spring drum located near one end of the typewriter frame, and where the end of the draw band is fixed to the carriage. Pins are provided on the frame and on the carriage, respectively, in such a way that they are aligned with one another when the carriage is in its middle position. The direction of movement of the carriage can be changed by eliding the draw band from one pi onto the other while the carriage is at its middle position, the band being supported on a slidable roll. The teaching of the present invention has no relation to a slidable draw band and its associated features.

Another solution is proposed in Israel patent No. 6518 which relates to a bookkeeping machine in which the numbers have to be written from left to right and the narration from right to left. The solution proposed consists in the provision of an electromagnet controlled by contacts actuated by the universal bar of the typing mechanism, which electromagnet operates the backspacing mechanism so as to provoke an escapement of the carriage by one step against the pull of the draw band any time a letter key has been actuated. While it is a common eature of patent 6518 and the present invention to use the known backspace mechanism for escapement in the reverse direction, the two solutions are distinct by the way the backspace mechanisms are operated. One disadvantage of the mechanism of patent 6518 is the necessity of having an electromagnet, a solenoid or a servo-motor and another is its limitation to typewriters having a universal bar. Further important disadvantages reside in the lack of provision for power-operated displacements of the platen or prin station with connection with said displacement, in connection with carriage or carrier return.

Israel patent No. 17345 discloses a carriage drive mechanism adapted to be coupled to the carriage in either of two dispositions, with displacing means operating the drive mechanism in dependence on their being fully actuated or not. The full actuation of the said displacing means is prevented by abutting means. The present invention does not make use of the alternative coupling of the carriage drive mechanism to the carriage nor does it have displacing means adapted to be operated either in full or less.

Yet another solution to the dual motion problem in typewriters is addressed in Israel patent Ho. 20940 which discloses an arrangement with two racks and an escapement pinion being engageable with either of the racks by means of a rack-reversing lever. In addition to this the direction of operation of the draw band 1B reversed. While the typewriter of the present Invention may be equipped with an escapement rack and a backspace rack, there is no engagement pinion, and accordingly, there is no relation between the solution of patent No. 20940 and the invention to be described.

Of course, to convert a typewriter from latin writing to writing in a script that calls for reversed movement not only requires the operational functions to be reversed but also the type face to be entirely changed. In conventional type "bar typewriters this change is not so easily implemented as a great number of type bars have to be exchanged, an operation that element requires considerable skill. With the advent of workable single/ typewriters in which the whole type font is arranged on the spherical surface of a type head, this situation has completely The present invention generally suggests a number of appropriate changes to be made in any single mode typewriter for it to be able to write in a direction opposite to the one for which it was originally designed.

The present invention more particularly has for its object a typewriter with dual motion capabilities where the conversion between the two modes is easily implemented.

An embodiment of the present invention will now be described by way of example with reference to a single element typewriter. It is clear that a man skilled in the art will be able to apply the teaching of this invention also to the conventional type bar typewriter. The following description will make reference to the attached drawings in which: . .

Fig. 1 is a perspective view of the essential parts of the print · escapement, space and backspace mechanisms; Fig. 2a, 2b show the conversion keybutton and the escapement trigger in two different positions; Fig. 3 shows the conversion of the backspace mechanism for effecting "reversed" print escapement; Fig. 4 shows the means for converting the space mechanism; SZ 9-67-004 - 3 - Fig . 5 is a view of the mechanism for the "rever s ed" backspace operation ; Fig . 6 is a perspective view of the connection between the . tabulator and index mechanism.

Typewriters for office us e or for. us e as input/output printer s for data proces sing equipment contain a number of operational functions which can be initiated manually by depr es sion of keybuttons on the keyboard or by energization of magnets as s ociated with the respective functional keys . The se functions include the print escapement, the spacing, the backspacing, the carriage or carrier return, the line spacing and the tabulator operations .

The e s capement mechanism controls the movement of the carriage or the carrier, as the case may be , along the writing line. The spacebar mechanism provides the operator with a means of moving the carriage or carrier one space along the writing line in writing direction without typing a character on the paper . It is- used, mainly for spacing between words . By means of the backspace mechanism the operator is enabled to move the carriage or carrier in the direction opposite to the writing direction . It is primarily used in error correction and in centering headings . The carriage or carrier return serves to enable the operator to start a new line , automatically providing a line spacing of the paper .

SZ 9- 67- 004 - 4 - The tabulator mechanism permits the operator to position the carriage or carrier quickly to a predetermined point on the writing line. The tabulator is used in typing columns of figures or for indenting paragraphs.

In power operated typewriters, all of these functions are initiated by depression of separate functional keybuttons provided on the keyboard of the typewriter, whereby the force the operator is to apply is determined solely by the reset spring associated with the respective key-button, while the functional, operation ifself is powered by the motor.

The typewriter designed in accordance with the present invention retains all of these functions for both modes of operation, i.e. when typing from left to right as well as when typing from right to left, without duplication, of the parts necessary for performing the said functions.

The typewriter of this invention rather makes use of the mechanisms present on each regular typewriter but employs some of them for different functions in the two modes of operation as will be shown in more detail hereafter.

The conversion between the two modes is being made as easy as possible: it works by simply switching a conversion keybutton on the keyboard from one position to the other.

In view of the fact that most of the typewriters on the market are SZ 9-67-004 - 5 - designed to write from left to right, as for Latin character s , this mode of operation - for the purpos es of the following des cription - will be called the "normal" mode , while the mode of operation enabling the writing from right to left will be designated the " rever sed" •mode . t Referring to Fig . l , the "normal" print escapement operation will now be des cribed. Always when one character has been printed, the type head carrier is to as sume a new position one unit space away from the previously printed character . Thus , the striking of a character keybutton not only s erves to actuate the type head for printing, it also causes the type head, carrier to advance in writing direction .

An escapement rack 1 is mounted solidly to the machine frame (not shown) behind the type head carrier and beneath an es capement bracket which forms part of the carrier . A s tud 2 on the bracket serves to support an escapement pawl 3 so that it pivots front to rear . A spring 4 extending from pawl 3 to the bracket exerts a force to the right and foreward on the es capement pawl 3. The pawl has an elongated hole 5 at its mounting point, that allows the pawl to move laterally. While the pawl 3 is engaged in the escapement rack 1 , the force of the mainspring of the typewriter holds the carrier to the right so that the pivot stud 2 rests against the end of the elongated hole 5.

SZ 9- 67- 004 - 6 - Briefly, an escapement operation is obtained by forcing the escapement pawl 3 to the rear out of engagement with the teeth of rack 1. Because it is relatively light in weight, the pawl 3 is snapped to the right by its spring 4 as soon as it comes clear of the rack tooth. The escapement pawl 3 is then allowed to move back to the front into engagement with the next tooth of rack 1. During this opera tion, the carrier advances one distance between two neighbouring teeth to the right until it comes to rest against escapement pawl 3.

The stud 2 serves also as a pivot point for a backspace pawl 6 which is normally in engagement with a backspace rack 7. For a backspace operation, the carrier must move to' the left, and since the backspace pawl 6 is mounted on the carrier, movement of pawl 6 forces the carrier and the escapement pawl 3 to the left. The backspace pawl 6 is held in mesh with the teeth of the backspace rack 7 by means of an extension spring 8. The backspace rack 7 is located below the escapement rack 1 and is suspended on the machine frame by means of shoulder screws extending through elongated holes in it. An extension spring 10 forces the rack 7 toward the right. The backspace rack 7 is actuated for a backspace operation by a bellcrank 11 through an adjustable intermediate lever 12 pivoted on a stud 13.

Upon depression of the backspace keybutton (not shown) a backspace interposer 14 ist released to the rear causing an operational latch 15 SZ 9-67-004 - '7 - to be pushed under a cam follower lever 16. Operation of the cam (not shown) causes the cam follower lever 16 to pull the latch down rotating the bellcrank 11 which in turn forces the backspace rack 7 to the left. The backspace pawl 6 resting against one tooth of rack 7 causes the carrier to follow the movement of rack 7. As the backspace rack 7 forces the carrier to the left, the escapement pawl 3 is allowed to click from one tooth of the escapement rack 1 to the next. Upon completion of the backspace operation bellcrank 11 releases the backspace rack 7 to return to its home position thereby causing the backspace pawl 6 to click behind the next tooth on rack 7.

As has been explained above, the print escapement and backspace operations require the -pawls 3 and 6 to come out of engagement with their respective racks 1 and 7. To this end, a flat torque bar 17 is pivotally supported in the machine frame just behind racks 1 and 7.

The pivot point of the torque bar 17 is near its bottom such that its pivoting causes its top to move to the rear. The escapement and backspace pawls 3 and 6 each have a lug extending down behind the bar such that when the bar 17 pivots, the tips of the pawls are cleared from the teeth of their racks.

An escapement trigger 18 is provided to rotate the torque bar 17 in order to obtain an escapement operation. The trigger 18 hooks on a SZ 9-67-004 - 8 - lug 19 attached to one end of the torque bar and pulls downward to cause the torque bar to rotate. The escapement trigger 18 is pivotally supported by a pin 20 on a lever 21 and is held forward over the lug 19 by an extension spring 22 between the lower end 23 of the escapement trigger and a rear extension 24 of the lever 21. Downward movement of the lever 21 carries the trigger 18. down to rotate the torque bar 1.7.

The lever is restored and held in its rest position by an extension spring . ' The lever 21 is operated by an escapement cam 26 mounted to a filter shaft 27. This shaft acts to operate the character selection mechanisms,, the print escapement, the shift interlock, and the spacebar lockout o device. Its rotation is restricted to 180 each time a character is printed. Resting on the escapement cam 26 is a cam follower 28 mounted on a lever 29 which is pivotally supported by a shaft 30. A link 31 serves to connect levers 29 and 21 in order to transmit the cam movement to the escapement trigger 18.

Depression of a character keybutton during the "normal" operation causes the filter shaft 27 to rotate by 180° actuating the escapement trigger 18 to rock the torque bar 17 which in turn clears the escapement and back- , space pawls 3 and 6, respectively, from their associated racks 1 and 7, thus permitting thie carrier to move one unit escapement step to the right.

SZ 9-67-004 - 9 - Depression of the backspace keybutton in the "normal'Operation causes the backspace interposer 14 to actuate the backspace bell- crank 11 which shifts the backspace rack 7 to the left forcing also the carrier to move to the left one unit step.

For a "reverse" printing operation the carrier must be able to move from right to left, and for a "reverse" backspace operation it must be able to move from left to right. To achieve the "reversed" print escapement, the backspace mechanism. described above is used togethe with the dead key mechanism and the velocity control. The dead key mechanism provides a non-escaping selection of some characters, e.g. the grave accent and the circumflex accent. When the dead key-button is depressed an associated bail (not shown), to which a wire cable 32 is attached, is moved foreward, thus exerting a pull on that wire cable which in turn is connected to the escapement trigger 18. Operation of the dead keybutton thus causes the escapement trigger 18 to pivot about pin 20 and to release lug 19 on the torque bar 17. With the escapement trigger disengaged from the torque bar, no motion can be imparted to the latter by the escapement cam 26 and accordingly, no escapement will occur after print. For the "reverse" operation of the typewriter, it is necessary that the "normal" escapement be prevented after each printing operation.

SZ 9-67-004 - 10 - 4 A conversion keybutton 33 (Fig.2) placed on the keyboard and having two positions, respectively associated with the "normal" (Fig.2a) and "reversed" (Fig.2b) modes of operation, is mounted on a conversion lever 34 which is pivotally supported on a stud 35. The lever 34 is connected to a control arm 36 by. means of a link 37. Also, connected to the control arm 36 is a dead key link 38 which is fixed to one of a pair of levers 39 and 40 swivel- mounted on a plate 41.

Attached, to lever 40 is the wire cable 32.

In the "normal" position of conversion keybutton 33, the intermediate mechanism is in its rest position and no pull is exerted on wire cable 32 (Fig.2a). Thus, the escapement trigger 18 is in engagement with the lug 19 on the torque-bar 17 and accordingly, an escapement operation is initiated. after each printing of a character. In the "reversed" position of conversion keybutton 33, however, its conversion lever 34 actuates link 37 which causes the motion in counter-clockwise direction of control arm 36 which in turn actuates the pair of levers 39 and 40 (Fig.2b). As the lever 40 rotates about its axis 42, it exerts a pull on wire cable 32, which causes the escapement trigger 18 to rotate in clockwise direction and to disengage from lug 19.

When a character is printed under these conditions, the operation of cam 26 (Fig.1) will have no effect on the torque bar 17 and thus no "normal" escapement will occur.

SZ 9-67-004 . . 11 X It is of course necessary that each character print be followed by an escapement operation, and in the "reverse" mode of operation this escapement should be from right to left. A spacing operation in this direction is "normally" obtained by actuation of the backspace mechanism. Therefore, for the "reverse" print escapement operation the "normal" backspace operation can be used. Provision must be made to operate the "normal" backspace mechanism upon each character print in the "reverse" mode of operation. How this can be obtained will now be described in detail.

As has been explained above, the filter shaft 27 (Figs. 1 and 3) revolves o 180 for each printing operation. Fixed upon the filter shaft is a double- lobed cam 43 (Fig.3). A cam follower 44 continuously follows the cam 43. Follower 44 is supported to pivot about a shaft 45. Pivoting about the same shaft is a cam follower stop 46 that is set- screwed to the follower 44. In engagement with the. lower end 47 of cam follower stop 46 is a latch 48 which is connected to the conversion keybutton 33 by means of a link 49 (Fig.2a and 2b).

A depression of the conversion keybutton 33 causes a pull on link 49 and with it a rotation of the latch 49 in counter-clockwise direction about its pin 50. The rotation of latch 48 provokes its disengagement from the cam follower stop 46. An extension spring 51 exerts a pull on the stop 46 SZ 9-67-004 - 12 - and on the set- screwed cam follower 44 which is now free to follow the cam 43 as it rotates upon printing. When the cam follower is on the low dwell of cam 43, it pulls on a wire cable 52 which is connected to the backspace interposer 14. A pull on wire cable 52 causes the backspace interposer to move downward - the same motion that is caused by pressing the backspace keybutton. Attached to the front of interposer 14 is a small pivoting latch 54. The latch is spring loaded upward against the interposer by a spring 55 so that its top portion forms a hook 56 for the interposer. The latch 5.4 hooks under a bracket 57 to hold the interposer foreward. When the interposer is pulled down by the wire cable 52, the hook 56 is released from bracket 57 allowing the interposer to be snapped to the rear by an extension spring 58.

Resting against interposer 14 is a hooklike latch 59 which is maintained against the interposer by a small spring 60. When the interposer is snapped to the rear, it forces the latch.59 to the rear to hook under a cam follower 61. The cam follower is then operated to pull down the latch 59 and actuate the backspace mechanism. The latter is not part of the present invention and will therefore not be described.

As the cam follower 61 is operated, the interposer 14 is restored to the front by a restoring lever 62. This causes the spring between the interposer and the latch 59 to be extended, and this tends to pull the SZ 9-67-004 - - 13 - latch out from under cam follower 61 before the operation is completed. In its restored position, the interposer is again latched by the hook 56 engaging the bracket 57.

From the foregoing description it will be clear that upon each depression of a character keybutton in the "reversed" mode of operation, the "normal" print escapement is suppressed by the dead key mechanism 32 through 40, while an escapement operation in the "reverse" direction is achieved by means of the backspace mechanism..

Another operation that is to be considered in a dual mode typewriter is the spacing operation which is used mainly for spacing between consecutive words. In the "normal" typewriter this operation causes the print head carrier to advance to the right one space at a time without typing of a character. In the "reversed" mode of operation, this spacing should cause the carrier to advanc.e to the left one space at a time.

The spacing operation is initiated by depression of a spacebar 63 (Fig.4) mounted in the keyboard of the typewriter just in front of the character keybuttons. The spacebar operates by tripping the escapement pawl 3 (Fig.l) and the backspace pawl 6 out of their racks 1 and 7, respectively, as on a print escapement operation. The two escapement operations are identical except for the method of actuating the escapement trigger lever 21.

SZ 9-67-004 - '14 - Attached to the right end of the spacebar shaft 64 is an operating arm 65 that touches down on a spacebar keylever 66 when the spacebar 63 is depressed. Movement of the keylever causes a pawl 67 to unlatch the spacebar interposer (which is not shown in the drawing). The latching mechanism has already been described in connection with the backspace mechanism, and in fact, the spacebar interposer. is identical with the backspace interposer 14 (Figs. 3 and 4). As the spacebar interposer is unlatched, it is snapped to the rear causing the spacebar cam (not shown) to operate, and pulling the escapement trigger lever 21 (Fig.1) down. Movement of this lever causes rotation of the torque bar 17 just as during a print escapement operation. As the torque bar 17 rotates, it forces the escapement pawl 3 and the backspace pawl 6 out of their respective racks allowing them to snap to the right. Meanwhile the torque bar 17 restores and lets the pawls re-enter their racks. The pawls move with the type head carrier until the escapement pawl 3 seats in the next. tooth of rack 1 to limit the movement of the carrier.

Mounted on the spacebar keylever 66 is a pin 68 which extends over the backspace keylever 69. Slideably supported on the latter is a horseshoe-like slider 70 that is permanently in contact with control arm 36. The control arm is operated by the conversion keybutton 33 by means of link 37, as shown in Figs.2a and 2b. In the "reversed" SZ 9-67-004 - 15 - mode of operation the slider 70 is slided to the front so that pin 68 is located above a shoulder 71 of slider 70. As the spacebar is depressed, the spacebar keylever 66 is moved down such that pin 68 presses onto shoulder 71 causing the backspace keylever 69 tcactuate its keylever pawl 3>Z. The pawl when moving down causes latch 54 to release the backspace interposer 14 which then initiates a "normal" backspace operation as described above . It is to be noted in this connection that the "normal" spacing operation that would occur upon depressing the spacebar, is prevented by the dead key mechanism which is active during the "reversed" operation under control of the conversion keybutton 33 (Figs. 2a and 2b).

In addition, a space interlock is used to keep the spacebar keylever pawl 67 out of engagement with the spacebar interposer (not shown). This interlock consists of a wire cable 72 connected with one end to the conversion lever 34 (Fig.2) and with the other end to keylever pawl 67. It will be clear to those skilled in the art that the wire cable 72 is secured by clamping means to appropriate places in the machine to guarantee its proper functioning.

The backspace mechanism provides the operator with a means of positioning the type head carrier one space in the direction opposite to the writing direction, in other words, it permits the type head to SZ'9-67-004 - 16 - ί return to the position where the last or any earlier character was printed. For the "normal" mode of operation, the backspace direction is from right to left; for the "reversed" mode of operation, the type head is to move from left to right for a backspace operation. This is the direction the type head moves into when a "normal" spacing operation is performed. The "reversed" backspace operation therefore makes use of the space mechanism. It is, however, necessary that an additional "reversed" backspace keybutton is provided on the keyboard.

Reference is now made to Fig.5 where a "reversed" backspace key-button 73 is fixed to a keylever 74 which is slideably supported by plate 41. Keylever 74 actuates a member 75 to which it is rotatably connected by means of a pin 76, the keylever being able .to pivot on a shaft 77. The member 75 is spring- loaded by a spring 78 attached to one of its ends, which spring'forces the member to rotate in clockwise direction. Also connected to keylever 74 is lever 40 whose pivot axis 42 is supported by keylever 74. Attached to the other end of member 75 is a wire cable 79 which links the member 75 to an arm 80 pivotally mounted to the front plate 81 of the interposer guide (not shown). The arm 80 has a protrusion 82 aligned with the space interposer 83 ¾f . &ί-¾¾* ¾'ΐ' -) .

As the "reversed" backspace keybutton 73 is depressed, its keylever 74 actuates member 75 such that it pivots about its shaft 77 exerting a pull SZ 9-67-004 - 17 - on wire cable 70j. This motion is transmitted to arm 80 which is pulled down against the force of a spring 84. The downward movement of arm 80 caus es its protrus ion 82 to engage the space interpos 83 which is lowered such that its latch is released in a way similar to that des cribed in connection with Fig . 3 for the backspace inter-pos er 14. Lowering the space interpo's er 83 causes it to be snapped to the rear thereby actuating the "normal" space mechanism which provokes a one- step carrier movement to the right.

It is to be noted that the depres sion of the backspace keybutton 73 caus e s the lever. 40 to be lowered, - since the axis 42 of that lever is connected to the keylever 74. Fig . 2a shows the cons tellation of the parts with the lever 40 lowered . The effect is that wire cable 32 is pushed s o that spring 22 may rotate the escapement trigger 1 8 to engage lug 1 9 of the torque bar 1 7. Thus the dead key mechanism is released from the control of the conversion keybutton 33 when the backspace keylever is depres sed.

After a typing line has been completed, the carrier is to return to the appropriate "margin - for the "normal" mode of operation to the left margin, for the "rever sed" mode to the right margin - , and an index operation is to be effected, i . e . the paper must be advanced . to the next writing line . An appropriate mechanism to perform this SZ 9- 67- 004 - . 1 8 - carrier return operation for the "reversed" mode of operation is the "normal" tabulator mechanism. Since the line spacing direction remains the same for both modes of operation, the regular index mechanism is to be connected to the tabulator mechanism. For the "reversed" carrier return operation it is mandatory that all previous tabulator stops be cleared. Only one tabulator stop is set to determine the right hand margin.

Since the tabulator mechanism per se does not form part of the present invention, only a very brief description thereof is given in order to facilitate the comprehension of its connection to the indexing mechanism. For a tabulator operation to take place, the escapement and backspace pawls 3 and 6 (Fig.l), respectively, must be released' from their racks 1 and 7 to allow carrier movement. The pawls must be latched in their released position to continue the movement, and they must be allowed to restore to their racks at the proper time. These two functions are performed by a tabulator lever (not shown) which is operated by a manual process. A tabulator keylever 85 (Fig.6), to which a tabulator keybutton 86 is attached, is mounted in the keyboard the same as the letter keylevers. Depression of the tabulator keybutton 86 causes via a connecting link and a bellcrank the tabulator torque bar to be tilted. This torque bar is. mounted the same as the escapement torque bar 17 (Fig.1). As the tabulator torque SZ 9-67-004 - 19 - bar is tilted, a lug at the front of a tabulator lever contacts the e s capement and backspace pawls 3 and 6 and forces them out of mesh with their racks 1 and 7. The pawls are then latched so that they are pr evented from interrupting the tabulator operation prior to the carrier reaching the next tabulator s top.

For the purpos e of the "reversed" mode of operation the tabulator mechanism is to be connected to the indexing mechanism so as to effect a line spacing operation upon " rever s ed" carrier return.

Accordingly, an additional keylever 87 is arranged in the keyboard. The lower end 88 of keylever 87 engages a bail 89 which is mounted in the machine frame underneath the keyboard. Keylever 85 rests with its lower end 90 on a roller 91 supported by the bail 89. As the tabulator keybutton 86 is depres sed, the bail 89 is pushed downward lowering 'keylever 87 to which is mounted a pin 92 extending over a line space slider 93 . The latter is supported by an index keylever 94 which is operable by an index keybutton 95 for initiating a manual line space operation. The line space slider 93 may be moved into either of two positions by the control arm 36. The way of operation of pin 92 and slider 93 is identical with that explained in connection with Fig . 4 for pin 68 and slider 70: In the "normal" mode of operation control arm 36 keeps, the shoulder 96 of slider 93 out of engagement with pin 92 when the latter is moved downward with its keylever 87.

SZ 9- 67- 004 - 20 - In the " r ever s ed" mode, however , pin 92 engages shoulder 96 upon- depres sion of tabulator keybutton 86 transmitting its motion to index keylever 94 which now initiates a line space operation, A manual actuation of index keybutton 95 does , of cour se, have no effect on the tabulator mechanism .

Obtaining a " revers ed" tabulation is pos sible, but only to a limited degree, by using the "normal" carrier return mechanism and the left margin stop. With that, "rever sed" tabulation can be achieved to a single position only. The carrier return mechanism in the "normal" mode of operation provides a powered return of the carrier to the left margin and an automatic line spacing of the paper . When us ed for the " revers ed" tabulation operation, the line spacing normally occurring with the carrier return is to be prevented.. The line spacing operation is controlled by an index interposer similar to the backspace interpos er 14 (Fig . 3) , and arranged adjacent to the latter underneath the keyboard. As has been explained in connection .with the backspace interposer , operation of the function as sociated with the interposer is obtained upon unlatching that imposer from ' the common bracket 57.. It will be clear to a man skilled in the art that it is merely neces sary to prevent unlatching of the index interpos er for the index operation to be suppres s ed, and this is to occur only when the "normal" carrier return keybutton is depressed to achieve a SZ 9- 67- 004 - 21 - I "revers ed11 tabulation operation . Accordingly, a wire cable could, for example, be arranged with one end underneath the carrier return keybutton, and with the other end fixed to the space interpos er . Means could be provided that, depending on the setting of the conversion keybutton 33 , would bring the wire cable into or out of engagement with the carrier return keybutton . With the conversion keybutton 33 in the "rever se" position , the wir e cable would have' to be placed underneath the carrier return keybutton so that upon the depression thereof the wire cable would be pushed to exert a holding pres sure on the index interpos er which is then maintained in its latched position . Thus , no index operation would occur . With the conversion keybutton 33 in its "normal" position , the wire cable will have to be removed fr om underneath the carrier return key-button so that the index interpos er is not prevented from being actuated during a carrier return operation.

SZ 9- 67- 004 - 22 - 28608/2

Claims (9)

1. Power-driven electric, typewriter designed to type in one direction, comprising a printing mechanism, a print escapement mechanism, space and backspace mechanisms, and tabulator and index mechanisms, characterized in that, in order to allow "reversed" typing, means are provided comprising a conversion key-button mounted on a pivotally supported keylever which is in operating connection with a wire cable via intermediary members, permitting the backspace mechanism to effect "reversed" print escapement and space operations, permitting the space mechanism to be operated to effect "reversed" backspace operations, and permitting the tabulator mechanism to be operable for "reversed" displacement of print station and platen with respect to each other for starting a new line, whereby the index mechanism is brought in functional connection with the tabulator mechanism.

2. Typewriter according to Claim 1, characterized in that the conversion keybutton is arranged to be able to assume two positions, respectively associated with the "normal" and "reversed" modes of operation of the typewriter, which keybutton in its "reversed" position converts the "normal" backspace mechanism to operate as a "reversed" print escapement mechanism while preventing "normal" print escapement, that the said conversion keybutton further converts the "normal" spacebar mechanism to effect "reversed" spacing, and that the said conversion keybutton connects the index mechanism to the tabulator mechanism. 28608/2^. 24 -

3. · Typewriter according to claim 1, characterized in that between an interpoeer of the backspace mechanism and a cam follower riding on a cam of the printing mechanism, a cable is connected such that it causes a backspace operation to be initiated by unlatching the interposer when the said cam follower exerts a pull on said cable, the cam follower being controlled by the conversion keybutton by means of intermediate links.

4. Typewriter according to claim 2, characterized in that the conversion keybutton is linked to a control arm which controls the position of a slider for bringing the latter into or out of engagement with a pin mounted on a spacebar keylever which is operable by the spacebar, the said slider being assembled on a keylever associated with the backspace mechanism so as to effect a backspace operation upon depression of the spacebar when the conversion ke -button assumes its "reversed" position.

5. · Typewriter according to claim 2, characterized in that the conversion keybutton is linked to a control arm which controls the position of an escapement trigger for bringing the latter into or out of engagement with a torque bar of the print escapement mechanism so as ½o permit print escapement in the "normal" position of the conversion keybutton, and to prevent print e scapement in the "reversed" position of the conversion keybutton.

6. # Typewriter according to claim 5, characterized in that the control arm is connected vit a link and levers to one end of a cable whose other end is fixed to the escapement rrigger in such a manner that the latter is brought out of engagement with the escapement torque bar when the conversion keybutton is in its "reversed position* 25 28608/2^

7. Typewriter according to claim 1, characterized in that a "reversed" backspace keybutton is provided to operate a lever pivotally supported so as to be able to etert a pull on a cable extending between said lever and an arm equipped with a protrusion which is aligned with an interposer of the space mechanism so as to actuate the said interposer ¾ en the said keybutton is depressed to initiate a "reversed" backspace operation.

8. Typewriter according to claim 2, characterized in that the conversion keybutton is linked to a control arm which controls the position of a slider for bringing the latter into or out of engagement with a pin mounted on a keylever which is operable by a tabulator keybutton, the slider being assembled on. a key> lever associated with the index mechanism eo as to effect a line space operation upon depression of the tabulator keybutton with which the "reversed" displacement between print station and platen is initiated, when the conversion keybutton is in its "reversed" position.

9. Typewri eraccording to any of the foregoing claims, characterized in that its printing mechanism comprises a single element print head which on its spherical surface carries the type faces and vhich is mounted on a carrier for being moved in writing direction with respect to the stationary platen. For the Applicants DR. RTNERS By: