RIBBON FEED AND REVERSING MECHANISM FOR TYPEWRITERS
United States Patent 3630337
A typewriter is provided with ribbon feed and reversing mechanism whereby when one ribbon spool becomes empty and the other correspondingly becomes full, the resistance to rotation of one or other spool causes the drive to be reversed so that as typing proceeds the ribbon is progressively wound back from the full spool to the empty one. There is a driving spindle which is rotated to and fro as the carriage makes its alternative typing and return traverses and racks one or other of two spool spindles through pawl and ratchet mechanisms. The driving spindle carries a cam which rotates inside an oscillatable member, and if the latter is prevented from rotating, oscillates the latter to operate the pawl and ratchet mechanisms. Upon one of these mechanisms encountering undue resistance to operation due to resistance of its spool to rotation, the oscillatable member is stepped round by the cam from one alternative position to another. The eccentric member carries an eccentric device which operates within a female member to displace the latter. Each pawl and ratchet mechanism is provided with a bluffing device, and according to the displaced position of the female member one or other of these devices is rendered operative to bluff its associated pawl and ratchet mechanism (thereby discontinuing the drive to the associated spool spindle) and the other of these bluffing devices is rendered inoperative to bluff the associated pawl and ratchet mechanism and the drive is thereby transferred to the other spool spindle.
US Patent References:
/1103300.html
Candsiedel - July 1914 - 1103300
Ribbon feed mechanism of typewriters
Byers - July 1962 - 3047120
/1103300.html
Candsiedel - July 1914 - 1103300
Ribbon feed mechanism of typewriters
Byers - July 1962 - 3047120
Application Number:
04/886262
Publication Date:
12/28/1971
Filing Date:
12/18/1969
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
400/220.200
International Classes:
B41J33/18; B41J33/48; B41J33/516; B41J33/14; B41J33/46
Field of Search:
197/160-165,151
Primary Examiner:
Pulfrey, Robert E.
Assistant Examiner:
Pellegrino, Stephen C.
Claims:
What is claimed is
1. A ribbon feed and reversing mechanism for a traversing carriage typewriter, comprising:
2. The apparatus as described in claim 1, wherein said bluffing means comprises a bluff-operating eccentric device rotationally movable with the oscillatable device between alternative positions for the alternative bluffing of the pawl and ratchet mechanisms, a female member encircling said eccentric device and displaceable thereby to alternative positions, and bluffing connections extending from said female member to each pawl and ratchet mechanism, whereby one of said mechanisms is nonoperative and the other operative according to the position of the female member.
3. The apparatus as described in claim 2, wherein said bluffing connection extending from said female member to each pawl and ratchet mechanism comprises a bluff bar movable endwise by said female member between bluffing and inoperative positions.
4. The apparatus as described in claim 1, wherein said driving cam has a plurality of crests for producing a plurality of oscillations of the oscillatable device during each revolution of the cam.
1. A ribbon feed and reversing mechanism for a traversing carriage typewriter, comprising:
2. The apparatus as described in claim 1, wherein said bluffing means comprises a bluff-operating eccentric device rotationally movable with the oscillatable device between alternative positions for the alternative bluffing of the pawl and ratchet mechanisms, a female member encircling said eccentric device and displaceable thereby to alternative positions, and bluffing connections extending from said female member to each pawl and ratchet mechanism, whereby one of said mechanisms is nonoperative and the other operative according to the position of the female member.
3. The apparatus as described in claim 2, wherein said bluffing connection extending from said female member to each pawl and ratchet mechanism comprises a bluff bar movable endwise by said female member between bluffing and inoperative positions.
4. The apparatus as described in claim 1, wherein said driving cam has a plurality of crests for producing a plurality of oscillations of the oscillatable device during each revolution of the cam.
Description:
CROSS REFERENCE TO RELATED APPLICATIONS
Reference is made to Brit. Pat. application No. 60,540/68 of 24th Dec. 1968, Edward Victor Byers, from which priority is claimed.
SUMMARY OF THE INVENTION
The invention concerns typewriters of the type having a traversing carriage, and two rotatable mountings for two ribbon spools between which spools the ribbon is fed as the carriage traverses, the mountings being driven alternatively in opposite directions so that the ribbon is first wound onto one spool and drawn off the other and is subsequently wound back onto the other spool and drawn off the first spool, whereby each spool is alternately wound and subsequently emptied. The invention is concerned with an improved mechanism for securing the automatic reversal of the ribbon feed when either spool becomes empty.
The invention therefore provides ribbon feed and reversing mechanism for a typewriter of the type specified, comprising a driver which is rotatable as the carriage traverses, alternative driving means driven by the driver for driving one mounting in one direction and the other in the reverse direction, and reversing means for automatically changing over from one driving means to the other upon predetermined resistance of a mounting to rotation and for thereby effecting the reversal of the ribbon feed.
Specifically, there may be a rotatable driving cam, a device oscillatable by the rotating driving cam and normally held in any one of alternative rotational positions by a detent unless prevented from being oscillated whereupon said device is moved by the cam from one to another of the rotational positions, pawl and ratchet mechanisms operable by said device to drive the spool mountings in opposite directions and each operable, on encounting predetermined resistance of the associated mounting to rotation, to prevent said device from being oscillated, a bluffing device for each pawl and ratchet mechanism each bluffing device being movable between a bluffing position in which the associated pawl and ratchet mechanism is inoperative and an inoperative position in which said associated pawl and ratchet mechanism is operative, and means whereby the rotational position of the oscillatable device determines which of the bluffing devices is operative.
According to an important subsidiary feature of the invention, the last said means comprises a bluff-operating eccentric device rotationally movable with the oscillatable device between alternative positions for the alternative bluffing of the pawl and ratchet mechanisms, a female member encircling the eccentric device and displaceable thereby to alternative positions, and bluffing connections extending from the female member to the pawl and ratchet mechanisms whereby one or the other of the latter is bluffed according to the position of the female member.
In order that the invention may be better understood, reference will now be made to the drawings accompanying the Provisional Specification in which:
FIG. 1 is a sectional elevation of the ribbon feed and reversing mechanism;
FIG. 2 is an inverted plan view of a portion thereof, partly in section;
FIG. 3 is an inverted plan of a further portion of the mechanism;
FIG. 4 is an end elevation of the pawl and ratchet mechanism for driving a representative one of the two ribbon mountings, while
FIG. 5 is an exploded view showing the main components of the feed and reversing mechanism.
In the accompanying drawings, those parts of the typewriter of the type specified, which are not essential to an understanding of the invention (e.g. the keyboard, platen, carriage and associated mechanisms) are not illustrated, such parts being of a conventional and generally understood character.
The ribbon feed and reversing mechanism comprises a driving spindle 10 which (being coupled to the carriage by any suitable mechanism, not shown) rotates first in one direction then the other as the carriage makes its alternate typing and return traverses, and two spool spindles 11, 12 each driven thereby through pawl and ratchet mechanism The three spindles are appropriately journaled in the frame or chassis 13 of the typewriter and the included angle between the lines joining the axis of spindle 10 with the axes of spindles 11 and 12 is 90° or nearly so. The upper ends of the two spindles 11, 12 constitute mountings for the removable reception of two typewriter spools 14, 15 between which the ribbon 16 extends. The function of the mechanism provided by this invention is to wind the ribbon off a full spool (such for example as 14) onto an empty spool (such for example as 15) and, when the initially full spool 14 becomes empty and the initially empty spool 15 becomes full, to reverse the direction of the ribbon feed so that the ribbon is then wound back onto the spool 14 from spool 15.
At their lower ends the spindles 11, 12 carry ratchet wheels 17, 18 respectively, having oppositely arranged teeth so that the spindles can be racked round in opposite directions. At its lower end the spindle 10 carries a driving cam 19 having a plurality of circumferentially spaced crests or lobes to produce a plurality of complete oscillations of the oscillating device, hereinafter described, in each revolution. In the illustrated construction cam 19 is substantially triangular and operates in a substantially square track recess 20 within a track wall 21 formed on the upper surface of a disc 22. This track wall 21 is located within holes 23a, 24a in annular portions 23, 24 formed on the ends of pawl-carrying bars 25, 26. Hole 23a in bar 25 is substantially circular and track wall 21 is a rotational fit in it. Hole 24a in bar 26 is elongated in the direction of the length of that bar. The other end of bar 25 has a pair of oppositely directed pawls 27 for racking the ratchet wheel 17 in one direction, and two recesses 28. Similarly the opposite end of bar 26 has two oppositely directed pawls 29 for racking the rack wheel 18 in the opposite direction, and two recesses 30. The first said end of bar 25 has a slot 30 in which a pin 31 on the first said end of bar 26 is engaged, the two bars being coupled together by a tension spring 32. This spring holds s detent nose 33 projecting inwards from the periphery of the hole 23a in bar 25 into engagement with any one of four detent notches 34 provided one in each of the four outer faces of the wall 22. It will thus be appreciated that the disc 22 (which, with its track wall 21 and parts 43, 44, 45 hereinafter mentioned, constitute the aforesaid oscillatable device) has four alternative rotational positions but is normally prevented from rotation, while feed is taking place, by detent nose 33 engaging in one of the notches 34.
As a result, for each complete rotation of the triangular cam 19 the disc 22 is caused to make three complete oscillations which oscillate the bars 25, 26 and so cause either spindle 11 or spindle 12 to be racked round by one or other of the pawl and ratchet mechanisms consisting of pawls 27 on the bar 25 and the teeth of ratchet wheel 17 and pawls 29 on bar 26 and the teeth of ratchet wheel 18. One or other of these pawl and ratchet mechanisms is bluffed or rendered inoperative while the other is rendered operative by bluffing mechanisms now to be described.
Below the pawl bars 25, 26 there are the respective bluff bars 35, 36 which are pivotally connected to one another at 37 at one end. Near its free end bluff bar 35 carries two upstanding pins 37 adapted to engage the recesses 28 in the underside of pawl bar 25, while near its free end the bluff bar 36 carries upstanding projections 38 adapted to engage the recesses 30 in the underside of pawl bar 26. The arrangement is such that if either bluff bar 35 or 36 is retracted towards the axis of shaft 10 the other one is projected. The projections 37 and 38 of the retracted bar 35 or 36 engage the recesses 28 or 30 of the pawl bar 25 or 26 and thus permit the pawls of that bar to engage the teeth of ratchet wheel 17 or 18 as the case may be. The projections 38 or 37 of the projected bluffing bar 36 or 35 are disengaged from these recesses and therefore hold the associated pawl bar 26 or 25 in an upper position in which its pawls cannot engage the associated ratchet wheel. Springs 41 acting on discs 42 urge the pawl bars 25, 26 downwards.
One bluffing bar is projected and the other retracted when either spool 14, 15 ceases to rotate, by the following mechanism. At the underside of disc 22 there is an annular wall 43 having projecting from it a long radial lug 44 and two shorter lugs 45 at 90° to lug 44. These lugs and annular wall in effect constitute an eccentric device; they are located in a hole 46 through a female member 47 on the end of bar 36. The periphery of hole 46 has four inwardly protruding lands 48 at 90° to each other. One of these lands is engaged by the long lug 44 and two others are engaged by the shorter lugs 45 while the remaining land is engaged by the periphery of wall 43. Thus according to whichever of the four lands 48 is engaged by the long lug 44 (that is to say, according to the rotational position of the disc 22 and the eccentric device) one or other of the bars 35, 36 will be held projected and the other retracted. In FIG. 3 the bar 36 is held projected, and bar 35 is retracted, and this results in spindle 11 being racked round the spindle 12 remaining stationary.
When either of the spool spindles 11, 12 is held against rotation, the associated pawl bar 25 or 26 is prevented from oscillating and this in turn prevents the disc 22 from being oscillated by the rotating cam 19. Rotation of the cam 19 therefore causes the disc 22 to rotate so that one of the notches 34 which has hitherto been engaged by the nose 33 is disengaged therefrom and the next notch 34 is brought to a position in which it is engaged with the nose. Thus the disc 22 and the parts 43 to 45 thereon make a movement through 90° between alternative positions and this causes the long lug 44 at the underside of disc 22 to remove itself from one land 48 on bar 36 (with which land it has hitherto been engaged to hold bluff bar 35 or 36 projected) and to move rotationally into engagement with the next land 48. Thereby the female member 47 is displaced and the first mentioned bluff bar is retracted and the other bluff bar is projected, with the result that the drive is transferred from one of the spindles 11, 12 to the other spindle so that the ribbon is wound alternatively onto spool 14 from ribbon 15 and subsequently onto spool 15 from ribbon 14.
The resistance to rotation of the spools, resulting in the changeover, occurs because one end of the ribbon 16 is anchored to spool 14 and the other end to spool 15. Thus when one spool becomes empty the pull of the ribbon prevents that empty spool and its spindle, from being rotated and simultaneously the fact that the end of the ribbon is anchored to the empty spool prevents the full spool, and its spindle, from being rotated.
Cam 19 is formed on the underface of a member 50 keyed to spindle 10 and positioned against a shoulder on the latter. The inner ends of bars 25, 26, 35, 36 and the disc 22, are position between member 50 and a disc 51 which is a push fit on the end of the spindle. This disc has a cylindrical boss 52 extending through disc 22 into engagement with the under face of cam 19.
The various parts 17, 18, 19, 22, 25, 26, 35, 36, 42, 50 and 51 may be moulded from a suitable "plastic" material.
It is within the scope of the invention to drive spindle 10 through a one-way coupling, or free wheel device, so that the spindle is only rotated as the carriage makes its typing traverses and is not rotated during the reverse traverses.
Reference is made to Brit. Pat. application No. 60,540/68 of 24th Dec. 1968, Edward Victor Byers, from which priority is claimed.
SUMMARY OF THE INVENTION
The invention concerns typewriters of the type having a traversing carriage, and two rotatable mountings for two ribbon spools between which spools the ribbon is fed as the carriage traverses, the mountings being driven alternatively in opposite directions so that the ribbon is first wound onto one spool and drawn off the other and is subsequently wound back onto the other spool and drawn off the first spool, whereby each spool is alternately wound and subsequently emptied. The invention is concerned with an improved mechanism for securing the automatic reversal of the ribbon feed when either spool becomes empty.
The invention therefore provides ribbon feed and reversing mechanism for a typewriter of the type specified, comprising a driver which is rotatable as the carriage traverses, alternative driving means driven by the driver for driving one mounting in one direction and the other in the reverse direction, and reversing means for automatically changing over from one driving means to the other upon predetermined resistance of a mounting to rotation and for thereby effecting the reversal of the ribbon feed.
Specifically, there may be a rotatable driving cam, a device oscillatable by the rotating driving cam and normally held in any one of alternative rotational positions by a detent unless prevented from being oscillated whereupon said device is moved by the cam from one to another of the rotational positions, pawl and ratchet mechanisms operable by said device to drive the spool mountings in opposite directions and each operable, on encounting predetermined resistance of the associated mounting to rotation, to prevent said device from being oscillated, a bluffing device for each pawl and ratchet mechanism each bluffing device being movable between a bluffing position in which the associated pawl and ratchet mechanism is inoperative and an inoperative position in which said associated pawl and ratchet mechanism is operative, and means whereby the rotational position of the oscillatable device determines which of the bluffing devices is operative.
According to an important subsidiary feature of the invention, the last said means comprises a bluff-operating eccentric device rotationally movable with the oscillatable device between alternative positions for the alternative bluffing of the pawl and ratchet mechanisms, a female member encircling the eccentric device and displaceable thereby to alternative positions, and bluffing connections extending from the female member to the pawl and ratchet mechanisms whereby one or the other of the latter is bluffed according to the position of the female member.
In order that the invention may be better understood, reference will now be made to the drawings accompanying the Provisional Specification in which:
FIG. 1 is a sectional elevation of the ribbon feed and reversing mechanism;
FIG. 2 is an inverted plan view of a portion thereof, partly in section;
FIG. 3 is an inverted plan of a further portion of the mechanism;
FIG. 4 is an end elevation of the pawl and ratchet mechanism for driving a representative one of the two ribbon mountings, while
FIG. 5 is an exploded view showing the main components of the feed and reversing mechanism.
In the accompanying drawings, those parts of the typewriter of the type specified, which are not essential to an understanding of the invention (e.g. the keyboard, platen, carriage and associated mechanisms) are not illustrated, such parts being of a conventional and generally understood character.
The ribbon feed and reversing mechanism comprises a driving spindle 10 which (being coupled to the carriage by any suitable mechanism, not shown) rotates first in one direction then the other as the carriage makes its alternate typing and return traverses, and two spool spindles 11, 12 each driven thereby through pawl and ratchet mechanism The three spindles are appropriately journaled in the frame or chassis 13 of the typewriter and the included angle between the lines joining the axis of spindle 10 with the axes of spindles 11 and 12 is 90° or nearly so. The upper ends of the two spindles 11, 12 constitute mountings for the removable reception of two typewriter spools 14, 15 between which the ribbon 16 extends. The function of the mechanism provided by this invention is to wind the ribbon off a full spool (such for example as 14) onto an empty spool (such for example as 15) and, when the initially full spool 14 becomes empty and the initially empty spool 15 becomes full, to reverse the direction of the ribbon feed so that the ribbon is then wound back onto the spool 14 from spool 15.
At their lower ends the spindles 11, 12 carry ratchet wheels 17, 18 respectively, having oppositely arranged teeth so that the spindles can be racked round in opposite directions. At its lower end the spindle 10 carries a driving cam 19 having a plurality of circumferentially spaced crests or lobes to produce a plurality of complete oscillations of the oscillating device, hereinafter described, in each revolution. In the illustrated construction cam 19 is substantially triangular and operates in a substantially square track recess 20 within a track wall 21 formed on the upper surface of a disc 22. This track wall 21 is located within holes 23a, 24a in annular portions 23, 24 formed on the ends of pawl-carrying bars 25, 26. Hole 23a in bar 25 is substantially circular and track wall 21 is a rotational fit in it. Hole 24a in bar 26 is elongated in the direction of the length of that bar. The other end of bar 25 has a pair of oppositely directed pawls 27 for racking the ratchet wheel 17 in one direction, and two recesses 28. Similarly the opposite end of bar 26 has two oppositely directed pawls 29 for racking the rack wheel 18 in the opposite direction, and two recesses 30. The first said end of bar 25 has a slot 30 in which a pin 31 on the first said end of bar 26 is engaged, the two bars being coupled together by a tension spring 32. This spring holds s detent nose 33 projecting inwards from the periphery of the hole 23a in bar 25 into engagement with any one of four detent notches 34 provided one in each of the four outer faces of the wall 22. It will thus be appreciated that the disc 22 (which, with its track wall 21 and parts 43, 44, 45 hereinafter mentioned, constitute the aforesaid oscillatable device) has four alternative rotational positions but is normally prevented from rotation, while feed is taking place, by detent nose 33 engaging in one of the notches 34.
As a result, for each complete rotation of the triangular cam 19 the disc 22 is caused to make three complete oscillations which oscillate the bars 25, 26 and so cause either spindle 11 or spindle 12 to be racked round by one or other of the pawl and ratchet mechanisms consisting of pawls 27 on the bar 25 and the teeth of ratchet wheel 17 and pawls 29 on bar 26 and the teeth of ratchet wheel 18. One or other of these pawl and ratchet mechanisms is bluffed or rendered inoperative while the other is rendered operative by bluffing mechanisms now to be described.
Below the pawl bars 25, 26 there are the respective bluff bars 35, 36 which are pivotally connected to one another at 37 at one end. Near its free end bluff bar 35 carries two upstanding pins 37 adapted to engage the recesses 28 in the underside of pawl bar 25, while near its free end the bluff bar 36 carries upstanding projections 38 adapted to engage the recesses 30 in the underside of pawl bar 26. The arrangement is such that if either bluff bar 35 or 36 is retracted towards the axis of shaft 10 the other one is projected. The projections 37 and 38 of the retracted bar 35 or 36 engage the recesses 28 or 30 of the pawl bar 25 or 26 and thus permit the pawls of that bar to engage the teeth of ratchet wheel 17 or 18 as the case may be. The projections 38 or 37 of the projected bluffing bar 36 or 35 are disengaged from these recesses and therefore hold the associated pawl bar 26 or 25 in an upper position in which its pawls cannot engage the associated ratchet wheel. Springs 41 acting on discs 42 urge the pawl bars 25, 26 downwards.
One bluffing bar is projected and the other retracted when either spool 14, 15 ceases to rotate, by the following mechanism. At the underside of disc 22 there is an annular wall 43 having projecting from it a long radial lug 44 and two shorter lugs 45 at 90° to lug 44. These lugs and annular wall in effect constitute an eccentric device; they are located in a hole 46 through a female member 47 on the end of bar 36. The periphery of hole 46 has four inwardly protruding lands 48 at 90° to each other. One of these lands is engaged by the long lug 44 and two others are engaged by the shorter lugs 45 while the remaining land is engaged by the periphery of wall 43. Thus according to whichever of the four lands 48 is engaged by the long lug 44 (that is to say, according to the rotational position of the disc 22 and the eccentric device) one or other of the bars 35, 36 will be held projected and the other retracted. In FIG. 3 the bar 36 is held projected, and bar 35 is retracted, and this results in spindle 11 being racked round the spindle 12 remaining stationary.
When either of the spool spindles 11, 12 is held against rotation, the associated pawl bar 25 or 26 is prevented from oscillating and this in turn prevents the disc 22 from being oscillated by the rotating cam 19. Rotation of the cam 19 therefore causes the disc 22 to rotate so that one of the notches 34 which has hitherto been engaged by the nose 33 is disengaged therefrom and the next notch 34 is brought to a position in which it is engaged with the nose. Thus the disc 22 and the parts 43 to 45 thereon make a movement through 90° between alternative positions and this causes the long lug 44 at the underside of disc 22 to remove itself from one land 48 on bar 36 (with which land it has hitherto been engaged to hold bluff bar 35 or 36 projected) and to move rotationally into engagement with the next land 48. Thereby the female member 47 is displaced and the first mentioned bluff bar is retracted and the other bluff bar is projected, with the result that the drive is transferred from one of the spindles 11, 12 to the other spindle so that the ribbon is wound alternatively onto spool 14 from ribbon 15 and subsequently onto spool 15 from ribbon 14.
The resistance to rotation of the spools, resulting in the changeover, occurs because one end of the ribbon 16 is anchored to spool 14 and the other end to spool 15. Thus when one spool becomes empty the pull of the ribbon prevents that empty spool and its spindle, from being rotated and simultaneously the fact that the end of the ribbon is anchored to the empty spool prevents the full spool, and its spindle, from being rotated.
Cam 19 is formed on the underface of a member 50 keyed to spindle 10 and positioned against a shoulder on the latter. The inner ends of bars 25, 26, 35, 36 and the disc 22, are position between member 50 and a disc 51 which is a push fit on the end of the spindle. This disc has a cylindrical boss 52 extending through disc 22 into engagement with the under face of cam 19.
The various parts 17, 18, 19, 22, 25, 26, 35, 36, 42, 50 and 51 may be moulded from a suitable "plastic" material.
It is within the scope of the invention to drive spindle 10 through a one-way coupling, or free wheel device, so that the spindle is only rotated as the carriage makes its typing traverses and is not rotated during the reverse traverses.