US3578132A

US3578132A - Half-space carriage return mechanism for typewriters

Info

Publication number: US3578132A
Application number: US702568A
Authority: US
Inventors: Venanzio Micheletti Cremasco; Domenico Roano
Original assignee: Olivetti SpA
Current assignee: Telecom Italia SpA; Olivetti SpA
Priority date: 1967-02-06
Filing date: 1968-02-02
Publication date: 1971-05-11
Anticipated expiration: 1988-05-11
Also published as: DE1611471A1; GB1189765A; FR1553357A; SE330031B; CH470262A; DE1611471C3; JPS4841654B1; DE1611471B2; BE710078A

Abstract

A half-space carriage return mechanism for typewriters, having a rack secured to the carriage and normally engaged by an escapement dog adapted to be disengaged momentarily from the rack to letter space the carriage, comprises a pawl movable in a first direction to engage the rack and to return the carriage half a space, and means actuatable for momentarily disengaging the pawl from the rack simultaneously with disengagement of the escapement dog when and only when the pawl is in the position in which it has backspaced the carriage through half a space, to cause said carriage to be advanced offset half a space with respect to normal letter spaced positions.

Description

United States Patent 2,212,692 8/1940 Kitchens 605,201 6/1898 Latta Inventors Appl. No. Filed Patented Assignee Priority HALF-SPACE CARRIAGE RETURN MECHANISM ITOR TYPEWRITERS 4 Claims, 3 Drawing Figs.

197/82, 197/ 84R Int. Cl B4lj 19/62 Field of Search 197/84,

References Cited UNITED STATES PATENTS Primary Examiner-Emest T. Wright, Jr. Attorney-Kevin C. McMahon ABSTRACT: A half-space carriage return mechanism for typewriters, having a rack secured to the carriage and normally engaged by an escapement dog adapted to be disengaged momentarily from the rack to letter space the carriage, comprises a pawl movable in a first direction to engage the rack and to return the carriage half a space, and means actuatable for momentarily disengaging the pawl from the rack simultaneously with disengagement of the escapement dog when and only when the pawl is in the position in which it has backspaced the carriage through half a space, to cause said carriage to be advanced offset half a space with respect to normal letter spaced positions.

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VENAN MICH TT' RE I OME NO HALF-SPACE CARRIAGE RETURN MECHANISM FOR TYPEWRITERS BACKGROUND OF THE INVENTION The present invention relates to a half-space carriage return mechanism for typewriters, having a toothed spacing member connected to the carriage and normally engaged by an escapement dog.

Various half-space return mechanisms of this kind are known. In general, with these mechanisms when it is desired to insert an omitted letter in a word, it is necessary to depress the backspace key as each typing key is depressed. Following the striking of each type, the backspace key must also be released. The combined action of the release of the backspace key and the operation of the escapement mechanism causes the carriage to advance; one space and a half instead of one space. There has already been proposed an arrangement for returning the carriage half a space, in which the escapement dog is mounted on a support which is displaced on the depression of the half-space return key, whereby the escapement tooth can.

thereafter be actuated while the half-space return key is kept depressed. Due to the dual function of the escapement dog, however, this arrangement is subject to trouble with the escapement and carriage rebound.

SUMMARY OF THE INVENTION tions, a pawl, a support pivotally mounting said pawl, a

depressible half-space carriage return key, means operable at the depression of said key for moving said support to displace said pawl so as to engage said spacing member and to return said carriage half a space, said operable means keeping said support so moved as long as said key remains depressed, means associated with said pawl and actuatable simultaneously with said spacing control means, and an element on said pawl normally ineffective for being operated by said associated means, said element upon so displacing said pawl becoming effective, said associated means when operating said element causing said pawl to turn on said support for tem-- porarily disengaging said spacing member thus causing said carriage to be advanced stepwise offset half a space with respect to said letter spaced positions.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial plan view of an electric typewriter incorporating a half-space return mechanism according to the invention,

FIG. 2 is a partial section taken on the line 11-11 of FIG. 1, and

FIG. 3 is a section taken on the line III-Ill of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring more particularly to FIG. 2, the reference 5 indicates generally the usual paper carriage of an electric typewriter, which is slidable transversely on a guide 6 fixed to the frame of the machine and is pulled towards the left (FIG. 1) by the conventional carriage draw spring indicated generally by the reference 7. Moreover, there is fixed to the carriage 5 a toothed spacing member formed by a rack 8 normally engaged by a movable escapement dog 9.

The escapement dog 9 is pivotally mounted on a pin 10 carried by a lever 11 and is held in engagement with the rack 8 by a spring 12. The lever 11 is pivotally mounted on a fixed pin 13 and is urged in a clockwise direction by a spring 14, the action of which predominates over that of the spring 12. As the action of the carriage draw spring 7 predominates over that of the spring 14, however, the rack 8 normally keeps the lever 11 bearing against a fixed stop 15. One end 16 of the lever 11 is normally engaged by a lug 17 of a hook 18 pivotally mounted on a fixed pin 19 and urged in a clockwise direction by a spring 20.

The escapement dog 9 is actuated to cause the carriage 5 to advance stepwise by means of a cam 21 (FIG. 2) which, on the depression of each typing key, is rotated through a cycle of in a known manner by a driving shaft 22 rotating continuously. Bearing normally against the cam 21 through the action of a spring 23 is a roller 24 on a lever 25 pivotally mounted on a fixed spindle 26. The lever 26 cooperates with a bent lug 75 of an escapement control lever 27 fixed on a shaft 28 rotatable on the machine frame. The lever 27 is provided with a projection 29 adapted to cooperate both with a projection 30 of the hook 18 (FIG. 1) and with one end 31 of a lever 32 having a slot 33 in engagement with a fixed pin 34. The lever 32 is normally kept bearing against the fixed stop 15 by a spring 35 and is provided with :1 lug 36 adapted to cooperate with a shoulder 37 of the escapement dog 9.

At each typing cycle, the cam 21 (FIG. 2) causes the lever 25 to rotate in an anticlockwise direction, whereby the control lever 27 is rotated in a clockwise direction. The projection 29 of the control lever 27 first engages the end 31 (FIG. I) of the lever 32, which is rotated in an anticlockwise direction. The lug 36 of the lever 32 then acts on the shoulder 37 of the escapement dog 9, which is disengaged from the rack 8. Immediately afterwards, the projection 29 engages the projection 30 of the hook 18, which releases the lever 11. By the effect of the spring 14, the liner 11 is now rotated in a clockwise direction until it is arrested against a fixed stop 38.

As the lever 11 rotates, it causes the escapement dog 9 to move towards the right and perform a retrograde stroke. The shoulder 37 of the escapement dog 9 now leaves the lug 36, whereby the spring 12 causes the escapement dog 9 to reengage the following tooth of the rack 8 independently of the action of the cam 21. Due to the action of the spring 7, the rack 8 now carries the dog 9 along towards the left, bringing the lever 11 back so that it bears against the fixed stop 15. If, after the reengagement of the escapement dog 9 with the rack 8, the lever 32 is still-held rotated, the lug 36 be to the left of the shoulder 37 when the carriage 5 moves to the left. The slot 33 then allows the lever 32 a certain movement along the pin 34. When the control lever 27 returns to the inoperative position, it permits the hook 18 to reengage the lever 11 and the lever 32 to return in any case to the position shown in FIG. 1.

The shoulder 37 (FIG. 1) allows the dog 9 to reengage the rack 8 in any case irrespective of the speed and the profile of the cam 21. The retrograde stroke of the dog 9 towards the right allows it to reengage under any circumstance with the rack 8 at the following gap. In fact, even though the profile of the cam 21 is such as normally to permit the spring 7 to shift the carriage 5 slightly to the left from standstill before the reengagement of the dog 9, when typing is done at speed the carriage 5 could be in a state of rebound at the instant of disengagement of the dog 9, whereby it would be shifted with some delay in respect to the case when the dog 9 is disengaged while the carriage 5 is at a standstill. The dog 9 would then be able to reengage the same gap in the rack 8, which would then be unable to effect the step of advance.

The typewriter is equipped with a mechanism for returning the carriage 5 half a space, said mechanism comprising a pawl 41 adapted to cooperate with the rack 8. The pawl 41 is fulcrumed on a pin 42 fixed on a support formed of a lever 43 fulcrumed on a fixed pin 44. Means for moving the lever 43 are provided, said means comprising a connecting rod 45 connected by a pin 39 and a slot 40 to the pawl 41. The connecting rod 45 is fulcrumed on a pin 46 of a lever 47 and is provided with a slot 48 engaging the pin 42. The connecting rod 45 is moreover equipped with a stud 49 normally bearing through the action of a spring 50 against a projection 51 of the lever 43. Finally, the pawl 41 is provided with an element or projection 52 adapted to cooperate with a pawl-tuming member formed of an arm 53 fixed on the shaft 28, when the pawl 41 is moved to the right with respect to the position of FIG. 1.

The lever 47 is pivotally mounted on a fixed pin 54 and is provided with an aperture 55 in which there is engaged one end of a lever 56 pivotally mounted on a fixed spindle 74 (FIG. 3). The lever 56 is equipped with a roller 57 normally bearing through the action of a spring 58 against a cam rotatable on the shaft 22. As the spring 58 prevails over the spring 50, it keeps the mechanism inoperative, as shown in FIG. 1. The cam 59 is arranged to be picked up for rotation with the shaft 22 by means of a clutch comprising a toothed wheel 60 fixed on the shaft 22 and a clutch pawl 61 pivotally mounted on the cam 59 at 62 and connected at 63 to a ring 64. The ring 64 in turn is connected to the cam 59 by means of two small levers 65 and a spring 66.

Normally, the ring 64 is arrested by engagement of a lug 67 thereon against a lug 68 of a lever 69 pivotally mounted at 70 and carrying the usual half-space return key 71. The lug 68 can moreover cooperate with a second lug 72 on the ring 64, which second lug 72 is about 180 from the lug 67 with respect to the shaft 22, but at a greater distance from the latter. The

key 71 can be depressed until it abuts against a fixed pin 73.

The half-space return mechanism operates in the following manner.

By depressing the key 71, the lug 68 of the lever 69 is brought clear of the lug 67 of the ring 64, but into the path of the lug 72. The spring 66 then causes the ring 64 to rotate in an anticlockwise direction (FIG. 3) with respect to the cam 59, causing the pawl 61 to engage with the wheel 60. Driven through the pawl 61, the wheel 60 now carries the cam 59 along in an anticlockwise direction from the inoperative position shown in FIG. 3 to an operative position in which the lug 72 is arrested against the lug 68 of the lever 69.

During this rotation, the cam 59 allows the spring 58 to rotate the lever 56 in an anticlockwise direction through a first stroke thus rocking the lever 47 (P10. 1) in a clockwise direction and moving the connecting rod 45 towards the right a predetermined stroke. The connecting rod 45 then rocks the lever 43 on the pin 44, whereby the pawl 41 is first with the rack 8, as shown in chain-dotted lines in FIG. 1, and then pushes the rack 8 together with the carriage backwards half a space against the action of the spring 7.

1f the key 71 is now released (FIG. 3), the lug 68 frees the lug 72 and is brought back into the path of the lug 67 of the ring 64. The

coupling

60, 61 is reengaged and causes the cam 59 to rotate through another 180 in an anticlockwise direction, as a result of which the carriage 5 returns to the original position.

If, on the contrary, the key 71 is kept depressed, the pawl 41 (FIG. 1) holds the carriage 5 shifted to the right half a space. if, keeping the key 71 depressed, a typing key is now depressed, when the lever 25 (P16. 2), rocks the arm 27 to disengage the escapement dog 9, the lever 53 (FIG. 3) rotates bodily with the arm 27 and the shaft 28 and temporarily disengages the pawl 41 from the rack 8.

The pawl 41 remains disengaged from the rack 8 for the time determined by the profile of the cam 21. This time is normally sufficient for the spring 7, causing the carriage 5 to start from standstill, to move the carriage 5 to the left by an amount such as to allow the pawl 41 to reengage the following tooth of the rack 8. The dog 9, on the other hand, reengages the following tooth of the rack 8 independently of the cam 21, as has been seen before. The carriage 5 can now advance one space to the left with respect to the initial position, being arrested again against the pawl 41. It is thus possible to effect the insertion of a character or symbol erroneously omitted by actuating the typing keys while the key 71 is kept depressed.

Since the typing speed which can be obtained in the case where the operator keeps the half-space return key 71 depressed is lower than the normal speed, the initially standing state of the carriage 5 at the time when the pawl 41 is disengaged is normally observed. If, by accident, the pawl 41 is not engaged with the rack 8, for example owing to the stopping of the shaft 22 before the end of the cycle of the cam 21, the rack 8 is stopped in any case by the escapement dog 9, whereby no disadvantage occurs.

it is therefore clear that the lever 27 and arm 53 fixed on the shaft 28 are able to disengage the pawl 41 shifted to the right temporarily from the rack 8 simultaneously with the escapement dog 9, to advance the carriage 5 one space out of phase by half a space with respect to the advance controlled by the dog 9.

It is understood that various modifications, improvements and additions of parts may be made in and to the half-space return arrangement hereinbefore described without departing from the scope of the invention as defined by the appended claims.

We claim:

1. In a typewriter having a transversely movable carriage, a toothed spacing member connected to said carriage, an escapement dog normally engaging said spacing member, and

. spacing control means actuatable to disengage said escapement dog temporarily from said spacing member to cause said carriage to advance stepwise to letter spaced positions, a halfspace carriage return mechanism comprising in combination:

a. a pawl,

b. a support pivotally mounting said pawl,

c. a depressible half-space carriage return key,

d. means operable at the depression of said key for moving said support to displace said pawl so as to engage said spacing member and to return said carriage half a space, said operable means keeping said support so moved as long as said key remains depressed,

e. means associated with said pawl and actuatable simultaneously with said spacing control means, and

f. an element on said pawl normally ineffective for being operated by said associated means, said element becoming effective when said operable means so displace said pawl, said associated means when operating said element causing said pawl to turn on said support for temporarily disengaging it from said spacing member simultaneously with disengagement of said escapement dog for causing said carriage to be advanced under the control of said pawl stepwise offset half a space with respect to said letter spaced positions.

2. A mechanism according to claim 1, wherein said toothed spacing member is formed of a rack secured to said carriage, comprising in combination:

g. a pawl-turning member included in said associated means and actuatable to engage said element, said element being normally out of the path of said pawl-tuming member and being brought on said path upon the displacement of said pawl by said operable means,

h. an escapement control member included in said spacing control means for causing disengagement of said escapement dog from said rack, and,

i. a connecting member for directly interconnecting said escapement control member and said pawl-turning member as to be secured to each other.

3. A mechanism according to claim 2, comprising in combination:

j. a first cam included in said operable means and power driven from an inoperative position to an operative position to so move said support on depression of said key and power driven from said operative position to said inoperative position on release of said key to cause said support to be restored, and

k. a second cam included in said spacing control means and power operated cyclically to actuate said pawl-turning and escapement control members in such a manner that said escapement dog when disengaged in this way performs a retrograde stroke and reengages said rack after said retrograde stroke independently of said first cam.

4. A half-spaced carriage return mechanism for a typewriter having a letter space carriage advance mechanism which includes an escapement dog engageable with a toothed spacing member connected to the carriage for holding the carriage against the action of the carriage advance biasing means, and means for disengaging the dog for allowing the carriage to advance under bias and for reengaging said dog with said spacing member for stopping said carriage after it has advanced one character space, comprising: I I

a pawl, normally uncoupled from said spacing member,

a depressible half-space carriage return key,

means operated by the depression of said key for displacing said pawl for engaging said pawl with said spacing member to return said carriage by one-half character space, said engaging means holding said pawl in its displaced position as long as said key is depressed, means coupled to and operable substantially simultaneously with said escapement dog disengaging means for disengaging said pawl, only when said pawl is in its displaced position, from said spacing member substantially simultaneously with the disengaging of said dog, and

means for recoupling said pawl with said spacing member to stop said spacing member after it has advanced under the influence of said biasing means a distance of onecharacter space from said half character space returned position.

Claims

1. In a typewriter having a transversely movable carriage, a toothed spacing member connected to said carriage, an escapement dog normally engaging said spacing member, and spacing control means actuatable to disengage said escapement dog temporarily from said spacing member to cause said carriage to advance stepwise to letter spaced positions, a half-space carriage return mechanism comprising in combination: a. a pawl, b. a support pivotally mounting said pawl, c. a depressible half-space carriage return key, d. means operable at the depression of said key for moving said support to displace said pawl so as to engage said spacing member and to return said carriage half a space, said operable means keeping said support so moved as long as said key remains depressed, e. means associated with said pawl and actuatable simultaneously with said spacing control means, and f. an element on said pawl normally ineffective for being operated by said associated means, said element becoming effective when said operable means so displace said pawl, said associated means when operating said element causing said pawl tO turn on said support for temporarily disengaging it from said spacing member simultaneously with disengagement of said escapement dog for causing said carriage to be advanced under the control of said pawl stepwise offset half a space with respect to said letter spaced positions.

2. A mechanism according to claim 1, wherein said toothed spacing member is formed of a rack secured to said carriage, comprising in combination: g. a pawl-turning member included in said associated means and actuatable to engage said element, said element being normally out of the path of said pawl-turning member and being brought on said path upon the displacement of said pawl by said operable means, h. an escapement control member included in said spacing control means for causing disengagement of said escapement dog from said rack, and, i. a connecting member for directly interconnecting said escapement control member and said pawl-turning member as to be secured to each other.

3. A mechanism according to claim 2, comprising in combination: j. a first cam included in said operable means and power driven from an inoperative position to an operative position to so move said support on depression of said key and power driven from said operative position to said inoperative position on release of said key to cause said support to be restored, and k. a second cam included in said spacing control means and power operated cyclically to actuate said pawl-turning and escapement control members in such a manner that said escapement dog when disengaged in this way performs a retrograde stroke and reengages said rack after said retrograde stroke independently of said first cam.

4. A half-spaced carriage return mechanism for a typewriter having a letter space carriage advance mechanism which includes an escapement dog engageable with a toothed spacing member connected to the carriage for holding the carriage against the action of the carriage advance biasing means, and means for disengaging the dog for allowing the carriage to advance under bias and for reengaging said dog with said spacing member for stopping said carriage after it has advanced one character space, comprising: a pawl, normally uncoupled from said spacing member, a depressible half-space carriage return key, means operated by the depression of said key for displacing said pawl for engaging said pawl with said spacing member to return said carriage by one-half character space, said engaging means holding said pawl in its displaced position as long as said key is depressed, means coupled to and operable substantially simultaneously with said escapement dog disengaging means for disengaging said pawl, only when said pawl is in its displaced position, from said spacing member substantially simultaneously with the disengaging of said dog, and means for recoupling said pawl with said spacing member to stop said spacing member after it has advanced under the influence of said biasing means a distance of one character space from said half character space returned position.