US3882990A

US3882990A - Error correction system for typewriters or printing devices

Info

Publication number: US3882990A
Application number: US330648A
Authority: US
Inventors: Jesus F Genesio
Original assignee: Messa Maquinas De Escrever S A
Current assignee: Messa Maquinas De Escrever S A; MESSA-MAQUINAS DE ESCREVER Sarl
Priority date: 1972-05-25
Filing date: 1973-02-08
Publication date: 1975-05-13
Anticipated expiration: 1992-05-13
Also published as: JPS4927327A; CH562691A5; DE2301565A1; ES411985A1; GB1418009A; IT986871B

Abstract

A novel error correction system applicable to any type of typewriter or printing apparatus having a ribbon with an appropriate strip for obliterating printed letters, comprises a correction key which is simultaneously associated (1) with the ribbon-position selection mechanism by means of a lever that, through the action of a spring, pulls the ribbon vibrator link to the correction position; (2) with the escapement mechanism by means of a link which causes the escapement impeller to move, thereby removing it from the normal operating position; and (3) with the backspacing system of the typewriter by means of a surface of the reverse lever which, by acting on a link screw, operates the backspace dog and therefore the typewriter carriage backspaces one space. When the correction system is engaged, however, the escapement impeller remains free to be operated if desired by a space bar.

Description

O United States Patent 11 1 1111 3,882,990

Genesio May 13, 1975 ERROR CORRECTION SYSTEM FOR 3,212,616 /1965 Frechette et 61.. l97/82 TYPE RITERS 0R PRINTING DEVICES 3,270,852 9/1966 Fondiller 197/181 X W 3,397,767 8/1968 Hobbs 197/181 [75] Inventor: Jesus F- n sl Al ueirao, 3,595,362 7 1971 Wolowitz l97/l8l x Portugal 3,729,081 4/1973 Ozimek et a] l97/l8l X [73] Assignee: Messa-Maquinas de Escrever,

' Prtmarv Exammer-Ernest T. Wright, Jr. .A. M S R L Mem amm Portugal Attorney, Agent, or F1rmBrOwdy & Nelmark [22] Filed: Feb. 8, 1973 [21] Appl. N0.: 330,648 S RACT A novel error correction system applicable to any type of typewriter or printing apparatus having a ribbon Foreign Apphcatlon Pnonty Data with an appropriate strip for obliterating printed let- May 25,1972 POl'IUgZll 57870 ters, comprises a correction y is Simultzb neously associated (1) with the ribbon-position selec- [52] U.S. Cl. 197/181; 197/91; 197/151; tion mechanism by means of a lever that through the l 97/157 action of a spring, pulls the ribbon vibrator link to the [51] Cl B41J correction position; with the escapement mecha [58] Field Of Search 197/91, 151, 156, 181, nism y means of a which causes the escapement l97/8O 157 impeller to move, thereby removing it from the normal operating position; and (3) with the backspacing [56] References C'ted system of the typewriter by means of a surface of the ITED STATES PATENTS reverse lever which, by acting on a link screw, oper- 1,223,279 4/1917 Helmond 197/80 ates the backspace dog and therefore the typewriter 1,290,723 l/l9l9 Dodge 197/82 carriage backspaces one space. When the correction 3,149,7Il 9/1964 Wolowitz 197/151 X tem is engaged, however, the escapement impeller WOIOWltZ X remains free to be operated desired a space bar 3,204,745 9/1965 Wolowitz 197/156 x 3,204,746 9 1965 Wolowitz 197 151 x 8 Clams, 8 Drawmg Flgures 80 7A 277 31 29 11 9 5A 7 fl I0 2e 11' I r 42 26A 5 g 8 25 44 1 52 20 1, 24 l oi i 'KL n 5 3 23 2 4 =g= g .a

PATENTEDHAYISISYS $882,990

SHEET 10? a PATENTED MAY 1 3 I975 SHEET 2 U? 4 ERROR CORRECTION SYSTEM FOR TYPEWRITERS OR PRINTING DEVICES FIELD OF INVENTION This invention concerns typewriters or printing apparatus and is related to the impression and colour systems. It consists of a mechanism providing the possibility of changing automatically the ribbon strip that operates the colour system and simultaneously positioning the machine carriage that supports the writing sheet or the printing system at the point where it is desired to print until such retention is released through subsequent action on the apparatus.

BACKGROUND It is common practice to correct printing errors by using a material that covers the wrongly printed character and which is normally white so as to be similar to the writing paper. The pigment is adherent to a strip of paper and covers the wrongly printed character by means of the type action of the printing system of the machine. The impregnated paper with the pigment is held manually by the typist who puts it between the writing sheet with the wrong character and the machine ribbon, with the pigment facing towards the writing sheet. To correctly apply this system, one must proceed as follows:

Backspace the machine carriage which supports the writing sheet or the printing system until the wrong character is at the printing position.

b. Place the pigment paper in the proper position to eliminate the wrongly printed character and strike again the wrong character.

c. Backspace the machine carriage or the printing system placing the erasure at the printing position.

d. Strike the correct character.

This system, although in common use, is somewhat cumbersome because it compels the typist to move out of her writing position with the resulting loss of efficiency.

Another system has been developed that consists in the use of a two strip ribbon of the usual black and red ribbon type, one strip, generally the upper one, being black, and the other strip being impregnated with an opaque pigment for the correction of errors. In a rough process using this type of ribbon, the correction is made in the following manner: I

a. Backspace the machine carriage with the writing sheet or the printing apparatus until the wrong character is in the printing position.

b. Operate the colour system in order to place the opaque pigment strip in the writing position.

c. Eliminate the wrongly printed character by striking again the wrong character.

d. Operate the colour selection system to set the black strip in the writing position.

e. Backspace the machine carriage or the printing apparatus placing the erased position in the writing position.

f. Strike the correct character.

A more developed process employing the same king of ribbon, as referred above, consists in the use of a special backspace key to correct mistakes. In this sytem. both backspace keys, the normal backspace and the auxiliary backspace, are connected to the colour selecting system so that. when making a correction, the

ribbon strip changes automatically whether the auxiliary backspace key or the normal key is operated.

In this system the correction is made in the following manner:

a. Using the auxiliary backspace, backspace the machine carriage that holds the writing sheet or the printing apparatus, until the wrong character is in the writing position. The ribbon is changed automatically to the opaque pigment.

b. Eliminate the wrongly printed character by striking again the wrong character.

c. Using the normal backspace, backspace the machine carriage or the printing apparatus to place the erased position in the writing position, the opaque pigment strip being changed automatically to the writing strip.

d. Strike the correct character.

SUMMARY The present invention refers to a correction system for typewriters wherein the machine carriage which holds the writing sheet or the printing apparatus, when backspaced to a wanted printing position, is held in that same position until the necessary erasure processes are accomplished and the correction is made by printing the correct character, and is released later on for the normal writing to proceed.

Another use of this invention is related to a system which applied in a typewriter permits it to print a character on a ribbon strip different from the normal writing one, without movement of the carriage which holds the writing sheet or the printing apparatus and without it being necessary to operate previously the normal system of ribbon-strip selection.

The invention can be applied to a typewriter or printing apparatus and this application will be described, or it can be used in a certain number of functions that require the following:

Simultaneous automatic change of the ribbon strip by operation of the colour system and retention of the carriage holding the writing sheet or the printing apparatus at a determined point until one or more operations are completed.

Retention of the carriage holding the writing sheet or printing system at a certain point until one or more operations are completed.

The invention will be described in relation to a carriage shift machine with an immovable printing system but it is applicable in typewriters with:

Segment shift A movable printing system, or

Carriage shift and movable printing system.

The invention will be described in relation to a typewriter with an error correction fixture which works with a ribbon having two longitudinal strips one of which has an ink enabling it to print the characters as usual, and the other having an opaque pigment which, when applied over a wrongly typed character, covers it completely so as to make it invisible and to permit the printing of the correct character.

In brief, the typewriter with error correction fixture has a special key correction key connected to the invented mechanism, which may have three positions.

1' position Rest position. In this position the correction fixture is not operated.

2"" position Selected by depressing the special key, starting from the rest position, until resistance is met. The key is then retained manually in this position.

3" position Obtained by depressing the special key until the end of its stroke, passing through the 2" position, and then releasing it (this position is automatically released by striking any key).

When the special key is depressed to take up the 3" position, the machine carriage backspaces a space and remains blocked, i.e. there is no escapement of the machine in the next stroke of any character, and the ribbon strip is changed so that the white strip is presented for the next stroke of any character.

When the key corresponding to the wrong character is depressed, this character is obliterated because it is covered by the white pigment, no movement of the machine carriage taking place, and the ribbon strip is changed so as to present the writing ribbon strip on the next stroke of any character. Finally, when the correct character key is depressed, this character is printed and the machine carriage proceeds as in normal typing.

In this summary description it is assumed that before the special key is depressed, the carriage has stopped at the position immediately following the one we wish to correct. However, the carriage may be stopped at any position after the one to be corrected. The special key must therefore be depressed until the end of its stroke as often as required to set the carriage with the wrong character in the printing position, the correction being then performed as above described.

In this summary description it is also assumed that when the key corresponding to the wrong character is depressed it stays completely covered by the white pigment. However, owing to wear or to ribbon imperfections the wrongly printed character may not be completely covered by the white pigment. In such a case, before depressing the key corresponding to the correct character, the special key must be depressed into its 2" position, and, while in this position, the key corresponding to the wrong character is struck as often as necessary for the character to be covered completely by the white pigment. The correct character key must then be depressed after the special key is released.

The invention provides for a key release key to release the correction fixture. This key is required, when, after depressing the special key it is found unnecessary to make a correction. In such a case, it will be necessary to release the correction fixture that was operated by the special key and that blocked the machine carriage and changed the ribbon strip, by depressing the release key once.

The correction of a character is made by the following operations:

I. Depress the correction key once or several times to set the character to be corrected at the printing position.

2. Depress the key corresponding to the wrongly written character.

3. Depress the key corresponding to the correct character.

An advantage of this invention is its simplicity in view of the small number of parts used in comparison with other inventions which function with the same sequence of operations.

Another advantage of this invention which does not exist in other existing error correction systems consists in the possibility of erasing perfectly the wrongly written character by means of several strokes on the wrong character, by selecting a certain position of the correction key (2"" position for the described invention). This enables difficulties due to wear or to imperfect ribbons to be overcome. In other existing error correction systems, the perfect erasure of the wrong character is only achieved by returning several times to the beginning of the operating sequence.

Another advantage of this invention not existing in other existing error correction systems, is the fact that when the correction key is in any of the two working positions, the machine escapement being blocked (so that no movement of the carriage occurs when any character is struck), the machine carriage may be moved by operating either the space bar or the carriage release lever without moving .the correction system from the position it occupies.

This advantage provides the user with great operating facilities especially in erasing operations of complete words.

BRIEF DESCRIPTION OF DRAWING For a better understanding of the device an..example is shown in no way restricting the invention of one of the ways of using the invention. This example is illustrated in the drawing in which:

FIG. 1A is a plan view of an embodiment showing the error correction device in its normal position;

FIG. 1B is a partial side elevation view of some elements shown in FIG. 1A;

FIG. 2A is a plan view of the same error correction device of FIG. 1A in a position corresponding to the 2" position of the special correction key which position is obtained by depressing the special correction key starting from the normal or rest position until a slight resistance is felt and holding it manually in that position;

FIG. 2B is a partial side elevation view similar to FIG. 1B, but in the second position; FIG. 2C is an enlarged plan view of a detail shown in FIG. 2A;

FIG. 3A is a plan view of the same error correction device of FIGS. 1A and 2A, in the corresponding position No. 3 of the special correction key which position is obtained by depressing the special correction key, starting from the normal or rest position, until the end of its stroke, going through the 2" position, and

FIG. 3B is a side elevation view similar to FIGS. 18 and 2B, but in the third position; and FIG. 4 is an exploded perspective view of the embodiment in the third position.

DETAILED DESCRIPTION Referring to the drawing in which the same parts are represented by the same reference numerals, there is provided a conventional typewriter keyboard provided with an extra or correction key 1 for effecting the purposes of the present device. The correction key 1 is connected to a lever 2 which is pivoted about a horizontal shaft 3. The back end of the lever 2 is connected to one end of an elongated link 4, and in turn the back end of the link 4 is connected to a reverse lever 5 which is pivoted about a vertical shaft 6.

Special correction key lever 2 is biased into its normal rest position by spring 19 connected to typewriter frame 55 as shown in FIG. 1B, 2B and 3B. This is a conventional form of insuring that

keys

1, 28, 30, once depressed, return to normal rest position upon release. Release key 30 and character keys 28 have a similiar spring biasing though not shown in the figures.

The back portion of the reverse lever 5 comprises a face 75 and a stop pawl 7 having a nose 7A. The pawl 7 is pivotally mounted along with reverse lever 5 on bolt 13 and has a pawl bar 80 as shown in FIGS. 1A, 2A, 2C, and 3A. Spaced adjacent the stop pawl 7 is a horizontal plate 40 mounted on the typewriter frame 55 as shown in FIG. 4. The plate 40 comprises a vertically extending flange 42 on which there is pivotally mounted, via a horizontal shaft 24, a positioning lever 8. A tension spring 23 extending from the plate 40 to I the bottom of positioning lever 8 urges the positioning lever 8 to the position of FIGS. 3A and 4. The positioning lever 8 has a surface 8A which engages the reverse lever face 75 when the special correction key 1 is in its first position as shown in FIG. 1A and discussed below, and the nose 7A of the pawl 7 when the special correction key 1 is in its second position as shown in FIGS. 2A and 2C and as discussed below.

Also connected to the bottom of the positioning lever 8 is the back end of an elongated link 25, the front end of which is connected through a slot 26A to a universal bar 26 which extends across the width of the keyboard. The universal bar 26 is provided with a round shaft 27 about which the universal bar 26 is capable of pivoting during usage of the invention by striking any character key as represented by character key 28, having a lever 29, during the correction procedure. A second extra key, or release key 30, engages the universal bar 26 by way of its lever 31.

The reverse lever 5 further comprises an arm 5B which angles back toward the keyboard. A spring 9 extends from the end of the arm 58 to a generally vertically extending lever 10 which is pivoted on a support 44 mounted to the typewriter frame 55 as shown in FIG. 4 about a horizontal axis 46. The lever 10 is provided with a notch 90 at its upper end in which a ribbon vibrator link 11 rests. The vibrator link 11 extends in one direction to a conventional ribbon vibrator mechanism shown generally at 48, and in the other direction extends to a conventional ribbon color selector 50. Mounted in the ribbon vibrator 48 in the conventional manner is a ribbon 91 consisting of at least two portions: 91A, containing a printing ink impregnant, and 91B impregnated with an opaque correction material.

A spring 18 urges the lever 10 to its most vertical posi-,

tlon.

The reverse lever 5 also has a surface 5A into which extends a screw 20 from a conventional backspace bellcrank 52 which lies below the reverse lever 5. Extending from the screw 20 is a link 21 which is connected to. and operates a backspace dog 22 which in turn meshes with a rack 54 in the normal manner. As shown in FIG. 4, the rack 54 is integrally connected to the paper support carriage 62 of the typewriter, shown in cutaway in FIG. 4, in the conventional manner; also, in the conventional manner, the paper support roll, not shown, is connected to the paper support carriage 62.

A bolt 13 on the reverse lever 5 is connected to a link 12 which extends across the typewriter to the escapement mechanism shown generally at 56. The mechanism 56 includes an escapement impeller 14 which normally effects movement of the carriage by rotating a rigid dog 58 thus causing a loose dog 60 to release the rack 54, all in a conventional manner. As shown in partial cutaway in FIG. 4, the rack 54 is also connected in the conventional manner to paper support carriage 62. Longitudinal movement of the escapement impeller 14 to advance the carriage 62 is effected by typing, i.e. depression of a key, such as key 28, and the consequent movement of its typebar35, connected to its respective key by link 36 in the conventional manner which moves a space arch 64; the space arch 64 in turn acts on the impeller 14 through linkages 66 which rotate about an axis 68 and exert pressure through a screw head 15, which extends through the impeller 14, on a bolt 16 connected to the impeller 14 and advancing the carriage 62. This is accomplished in the conventional manner by an impeller stud 92 engaging the arm ofa release lever 94 and rotating the release lever 94 about its axis 93 thus rotating the rigid dog 58 and effecting movement of the carriage 62 as explained above.

Also, in the conventional manner, a space bar 96 can effect advancement of carriage 62. This is done by pressing down on the space bar 96 which rotates a space bar lever 98 about its axis, i.e., the horizontal bar 97. This action causes the escapement impeller 14, which is connected to the space bar lever 98 by a space link 99, to move in the same direction as discussed above with regard to linkage 66 movement. This in turn engages release lever 94 with escapement impeller stud 92 causing the rack 54, and consequently carriage 62, to advance.

The link 12 is connected to the impeller 14 via a spring at point 72. A spring 17 biases the impeller 14 in its normal operative position so that screw head 15 is in contact with the bolt 16 to provide normal advancement of the carriage during typing.

When the correction key 1 is depressed until a slight resistance is felt and is kept in the same position by letting the finger remain on it (position No. 2 see FIG. 2B), this causes the rotation of lever 2 aroung shaft 3 and pulls link 4 that rotates the reverse lever 5 around shaft 6 until the stop pawl 7 encounters a slight resistance offered by the positioning lever 8. This slight resistance is caused by nose 7A of the stop pawl 7 engaging the surface 8A of lever 8. This is shown more clearly by referring to FIGS. 2A and 2C. In FIG. 2C nose 7A of pawl 7 has been engaged by surface 8A of positioning lever 8. Pawl 7 has rotated slightly due to the pressure exerted by surface SA on nose 7A, but rotation of pawl 7 is blocked by pawl bar engaging reverse lever 5 as shown in FIG. 1A. Through the action of nose 7A engaging surface 8A reverse lever 5 is thus maintained in the position shown in FIG. 2A until universal bar 26 is engaged by depressing any character key 28. This rotates positioning lever 8 through the movement of elongated link 25 and against the spring bias of tension spring 23. The rotation of positioning lever 8 disengages surface 8A from nose 7A allowing spring 9 to return reverse lever 5 to its normal position shown in FIG. 1A.

As shown in FIGS. 3A and 33 when the special correction key 1 is depressed to the full extent of its stroke, elongated link 25 is moved in the direction of the arrow in FIG. 2A by the special correction key ls lever 2 engaging universal bar 26 as shown in FIG. 3B. This causes reverse lever 5, under the urging of elongated link 4, to rotate past the point where nose 7A engages surface 8A. This results in reverse lever 5 rotating to a position shownin FIG. 3A after special correction key 1 is released. Positioning lever 8 under the urging of tension spring 23 rotates to block the rotation of reverse lever 5 under the urging of its biasing spring 9. Pawl 7 and reverse lever 5 engage positioning lever 8 as shown in FIG. 3A. This causes pawl 7 to rotate in a direction opposite to that which it rotated when special correction key I was in the position described above with respect to FIGS. 2A and 2C. This rotation of pawl 7 is partially blocked by pawl bar 80 engaging reverse lever as shown in FIG. 3A.

The rotation of reverse lever 5 causes the operation of two devices as follows:

I. COLOUR SELECTION DEVICE Lever under the action of spring 9 pulls the ribbon vibrator link 11 to the correction position as shown in FIG. 2A i.e. to a position in which the white correction strip 918 of the ribbon 91 is presented in the next stroke of any character.

2. ESCAPEMENT DEVICE Link I2 pulled by bolt 13 laterally moves the escapement impeller 14 through the spring 70 against the action of the spring 17 keeping the impeller 14 from operating because the bolt 16 is moved away from screw head 15.

This process of by passing carriage advancement enables the wrong character to be struck as often as necessary to complete the erasure without movement of the carriage 62 by means of the operation of space arch 64, although the carriage 62 can be advanced by means of the space bar 96 which operates the escapement impeller 14 in the conventional manner.

By taking the finger from the correction key 1 the whole correction device returns to its initial position owing to the tension of springs 9, I7 and 18.

In a similar way to that described previously, when the correction key I is depressed to the end ofits stroke (position No. 3 see FIGS. 3 and 4), it rotates lever 2 around shaft 3 and pulls link 4 that rotates the reverse lever 5 around shaft 6.

The rotation of the reverse lever 5 operates several devices as follows:

1. Positioning Device Lever 8 when free from the opposition of the stop pawl 7 and reverse lever 5, turns around shaft 24 by the action of spring 23 to a position that permits retention of the reverse lever 5. In its rotation movement lever 8 drags link 25 to the position shown in FIG. 3A with the front end of-the link 25 at the back end of the slot 26A.

3. Backspace Device The surface 5A of the reverse lever 5 acting on screw of link 2l operates the backspace dog 22. The machine carriage backspaces one space.

4. Escapement Device Link 12 pulled by bolt 13 laterally displaces the escapement impeller 14 removing it from the work area so that thecarriage will not advance because the screw head 15 does not act on bolt 16.

The simultaneous action of these four devices with retention of the reverse lever 5 by lever 8 permits the wrong character to be obliterated without movement of the machine carriage 62.

The correction device returns to the initial or normal writing position after any character, for example character key 28, is struck by means of the respective lever 29 acting on universal bar 26. The bar 26 turns around shaft 27 and pulls link 25 which rotates the positioning lever8 to its normal position. With the rotation of lever 8 there is a release of the reverse lever 5 and the whole mechanism returns to its rest position shown in FIG. 1A under the action of tension springs l7 l8 and 9. The correct character may then be printed in the space of the wrong character obliterated. and the carriage 62 then advances in the normal manner.

The error correction device provides for the use of a correction device release key 30. This key 30 is always used when the correction key 1 is operated to its 3"" position, and it is then found not necessary to perform any correction. Depressing key 30, by means of the respective lever 31, acts on universal bar 26. This bar 26 turns around shaft 27 and drags link 25 which causes rotation of lever 8 to the normal position shown in FIG. 1A. With the rotation of lever 8 the release of the reverse lever 5 occurs and the whole device returns to the normal or rest position under the action of springs l7, l8 and 9.

The device according to the invention, besides the referred advantages. has many others, such as:

When the machine carriage 62 is stopped in a position after the one to be corrected, successive backspaces can be performed with the correction key 1 so as to place the wrong character in the printing position.

When the correction device is operated, i.e. set to erase, the machine carriage 62 can be moved by the space bar 96 or manually, either in one direction or the other.

It has a release key 30 for the device. The largest parts of the system are wire links and springs leading to great simplicity and economy in manufacture and maintenance.

I claim: I. In a typewriter for use with ribbons providing a printing field and a print-obliterating field, said typewriter including a printing means comprising a plurality of character keys for printing on paper:

means to support the paper; means for normal advancement of said paper support means during the printing operation including an escapement impeller and a space arch operatively connected to said escapement impeller to effect advancement of said paper support means when any of said character keys is depressed;

advancing means for advancing said paper support means independent of said space arch, said advancing means including a space bar operatively connected to said escapement impeller for advancing said paper support means independent of said space arch;

means for positioning a ribbon between said printing means and the paper on said paper support means; means to select the ribbon field; and

means to'"'backspace said paper support means, the

improvement comprising:

correction means comprising means to simultaneously l operate said backspace means, (2) operate said means to select the ribbon field to shift to a print-obliterating field and (3) bypass advancement of said paper support means by preventing operation of said escapement impeller by said space arch and without interference with said means for advancing said paper support means independent of said space arch, so that said paper support means can be moved, by said means for advancing said paper support means independent of said space arch, after engagement of said correction means, while operation of said space arch does not effect operation of said means for normal advancement of said paper support means.

2. A device in accordance with claim 1, wherein said correction means comprises a correction key having three positions including a first rest position, a second position and a third position, said correction means effecting, (1) said operation of said backspace means, (2) said operation of said means to select the ribbon field, and (3) said bypassing of advancement of said paper support means by prevention of advancement of said escapement impeller by said space arch, when said correction key is in said third position; and

when said correction key is in said second position said correction means effecting only (1) said operation of said means to select the ribbon field, and (2) said bypassing of advancement of said paper support means by prevention of advancement of said escapement impeller by said space arch;

said correction means further comprising means to maintain said correction key in said third position during print-obliterating.

3. A device in accordance with claim 2 further comprising release means to disengage said correction means whereby said correction key returns from said third position to said first position without effecting print-obliterating, said release means including a release key.

4. A device in accordance with claim 2 wherein said correction means further comprises means to return said correction key from said third position to said first position upon the striking of a character key to effect print-obliterating.

5. A device in accordance with claim 1, wherein said correction means comprises:

a correction key and a generally horizontally disposed reverse lever controlled by said correction key;

ribbon shifting means controlled by said reverse lever;

means associated with said reverse lever to operate said backspace means upon movement of said reverse lever; and

bypass means controlled by said reverse lever to prevent operation of said escapement impeller by said space arch. thereby preventing advancement of said paper support means during striking one of said plurality of character keys to effect printobliterating;

said bypass means comprising bypass linking means extending from said reverse lever to said escapement impeller to move said escapement impeller laterally upon movement of said reverse lever so that the striking of one of said plurality of character keys will not effect longitudinal movement of said escapement impeller to thereby advance said paper support means; A

spring means urging said escapement impeller in the lateral direction opposite from said linking means.

6. A device in accordance with claim 5, wherein said correction means further comprises positioning and return means to initially position said reverse lever during print-obliterating and to then return said correction key to said first position after print-obliterating, said positioning and return means comprising:

a generally vertically disposed positioning lever,

spring means biasing said positioning lever into interference with said reverse lever, positioning lever linking means extending from said positioning lever toward said correction key, a universal bar means connected to the correction key end of said positioning lever linking means;

said universal bar means being so positioned that when the correction key is depressed to the third position thereof thereby causing positioning of said reverse lever by interference with said positioning lever, and thereafter said universal bar means is struck by depressing one of said plurality of character keys of said printing means, said positioning lever linking means is pulled by said universal bar means and said positioning lever is thereby pulled against the action of said spring biasing means thereby permitting, by removing the interference of said positioning lever with said reverse lever, rotation of said reverse lever and return of said correction key to the first position thereof.

7. A device in accordance with claim 5 wherein said bypass linking means comprises an elongated link extending from said reverse lever and a spring extending from said elongated link to said escapement impeller.

8. A device in accordance with claim 5 wherein said ribbon shifting means comprises a generally vertically disposed ribbon shifting lever connected to said reverse lever by a connecting spring, and a ribbon vibrator link controlled by said ribbon shifting lever; and

wherein said means to operate said backspace means comprises a connection between said reverse lever and said backspace means.

Claims

1. In a typewriter for use with ribbons providing a printing field and a print-obliterating field, said typewriter including a printing means comprising a plurality of character keys for printing on paper: means to support the paper; means for normal advancement of said paper support means during the printing operation including an escapement impeller and a space arch operatively connected to said escapement impeller to effect advancement of said paper support means when any of said character keys is depressed; advancing means for advancing said paper support means independent of said space arch, said advancing means including a space bar operatively connected to said escapement impeller for advancing said paper support means independent of said space arch; means for positioning a ribbon between said printing means and the paper on said paper support means; means to select the ribbon field; and means to backspace said paper support means, the improvement comprising: correction means comprising means to simultaneously (1) operate said backspace means, (2) operate said means to select the ribbon field to shift to a print-obliterating field and (3) bypass advancement of said papeR support means by preventing operation of said escapement impeller by said space arch and without interference with said means for advancing said paper support means independent of said space arch, so that said paper support means can be moved, by said means for advancing said paper support means independent of said space arch, after engagement of said correction means, while operation of said space arch does not effect operation of said means for normal advancement of said paper support means.

2. A device in accordance with claim 1, wherein said correction means comprises a correction key having three positions including a first rest position, a second position and a third position, said correction means effecting, (1) said operation of said backspace means, (2) said operation of said means to select the ribbon field, and (3) said bypassing of advancement of said paper support means by prevention of advancement of said escapement impeller by said space arch, when said correction key is in said third position; and when said correction key is in said second position said correction means effecting only (1) said operation of said means to select the ribbon field, and (2) said bypassing of advancement of said paper support means by prevention of advancement of said escapement impeller by said space arch; said correction means further comprising means to maintain said correction key in said third position during print-obliterating.

5. A device in accordance with claim 1, wherein said correction means comprises: a correction key and a generally horizontally disposed reverse lever controlled by said correction key; ribbon shifting means controlled by said reverse lever; means associated with said reverse lever to operate said backspace means upon movement of said reverse lever; and bypass means controlled by said reverse lever to prevent operation of said escapement impeller by said space arch, thereby preventing advancement of said paper support means during striking one of said plurality of character keys to effect print-obliterating; said bypass means comprising bypass linking means extending from said reverse lever to said escapement impeller to move said escapement impeller laterally upon movement of said reverse lever so that the striking of one of said plurality of character keys will not effect longitudinal movement of said escapement impeller to thereby advance said paper support means; spring means urging said escapement impeller in the lateral direction opposite from said linking means.

6. A device in accordance with claim 5, wherein said correction means further comprises positioning and return means to initially position said reverse lever during print-obliterating and to then return said correction key to said first position after print-obliterating, said positioning and return means comprising: a generally vertically disposed positioning lever, spring means biasing said positioning lever into interference with said reverse lever, positioning lever linking means extending from said positioning lever toward said correction key, a universal bar means connected to the correction key end of said positioning lever linking means; said universal bar means being so positioned that when the correction key is depressed to the third position thereof thereby causing positioning of said reverse lever by interference with said positioning lever, and thereafter said universal bar means is struck by depressing one of said plurality of character keys of said printing means, said positioning lever linking means is pulled by said universal bar means and said positioning lever is thereby pulled against the action of said spring biasing means , thereby permitting, by removing the interference of said positioning lever with said reverse lever, rotation of said reverse lever and return of said correction key to the first position thereof.

8. A device in accordance with claim 5 wherein said ribbon shifting means comprises a generally vertically disposed ribbon shifting lever connected to said reverse lever by a connecting spring, and a ribbon vibrator link controlled by said ribbon shifting lever; and wherein said means to operate said backspace means comprises a connection between said reverse lever and said backspace means.