US3455429A - Escapement mechanism for a carriage - Google Patents

Description

July 15, 1969 H. SCHWEIZER I ESCAPEMENT MECHANISM FOR A CARRIAGE 7 Sheets-Sheet 1 Filed June 1, 1966 5 5 2 mm 3 mm m a 5 J. W. t

INVENTOR HORST SCHIEI ER "ML ATTORNEY July 15, 1969 H. SCHWEIZER v ESCAPEMENT MECHANISM FOR A CARRIAGE 7 Sheets-Sheet 2 Filed June 1, 1966 N Q ww 319 a 1 R mw H M I V f: ANN 3 w w q E 5 a l f: a x a all C 5 Rh 11 B INVENTOII HORST SCHRBIZBR ATTORNEY July 15, 1969 H. SCHWEIZER 3,455,429

ESCAPEMENT MECHANISM FOR A CARRIAGE Filed June 1, 1966 T Sheets-Sheet 5 INVEN'I'OR HORST SCHWEIZER Tommy July 15, 1969 H. SCHWEIZER ESCAPEMENT MECHANISM FOR A CARRIAGE 7 Sheets-Sheet 4 Filed June 1, 1966 QM UE INVENTOR HORST SCHHEIZER (es M ATTORNEY July 15, 1969 H. SCHWEIZER ESCAPEMENT MECHANISM FOR A CARRIAGE '7 Sheets-Sheet 5 Filed June 1, 1966 INVENTOR HORST SCHWEIZER ATTORNEY y 1969 H. SCHWEIZER 3,455,429

ESCAPEMENT MECHANISM FOR A CARRIAGE Filed June 1, 1966 7 Sheets-Sheets INVBNTOR HORST SCHHBIZER ATTORNEY July 15, 1969 H. SCHWEIZER ESCAPEMENT MECHANISM FOR A CARRIAGE 7 Sheets-Sheet '7 Filed June 1. 1966 INVENTOR HORST SCHWEIZER "My A'r'ronunv United States Patent 3,455,429 ESCAPEMENT MECHANISM FOR A CARRIAGE Horst Schweizer, Wilhelmshaven, Germany, assignor to Olympia Werke A.G., Wilhelmshaven, Germany Filed June 1, 1966, Ser. No. 554,951 Claims priority, appligltiloi Germany, June 1, 1965,

Int. Cl. B41j 19/58, 19/62 U.S. Cl. 197-84 18 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to an escapement mechanism for the paper carriage of a typewriter, and more particularly to an escapement mechanism permitting carriage steps of diiferent length proportionate to the dimensions of a typed character.

It is one object of the invention to improve known escapement mechanisms serving this purpose, and provide an escapement mechanism which reliably operates, is of simple construction, and can be inexpensively manufactured.

Another object of the invention is to provide an escapement mechanism permitting proportionate spacing of typed characters, and providing particularly great play between the escapement pawls and the teeth of the carriage rack before the falling of the pawls into recesses of the rack.

Another object of the invention is to provide an escapement mechanism capable of controlling carriage steps which are equal to, or greater than the pitch of the carriage rack.

This object of the invention cannot be obtained by known escapement mechanisms, which require a number of escapement pawls at least corresponding to the number of different carriage steps.

Another object of the invention is to provide an escapement mechanism requiring only a comparatively small number of pawls for obtaining a greater number of carriage steps, so that a carriage rack of smaller thickness than in known constructions can be used.

The escapement mechanism of the present invention employs a set of escapement pawls which are mounted for turning and translatory movement so that an engaging portion or tooth on each escapement pawl can move rearwards relative to the rack of the carriage which moves forward in writing direction under the action of a carriage spring.

The engaging portions of the pawls have dilferent distances from stop portions thereon which engage a blocking shaft on which the pawls are mounted. The stop portions are staggered relative to each other a predetermined distance which is an integral fraction of the pitch of the rack bar, and the number of escapement pawls is the pitch of the rack bar divided by the predetermined distance. One of the pawls is at any time in a blocking position abutting a tooth of the carriage rack with an engaging portion, and abutting a blocking shaft with a stop portion so that a carriage cannot move under the action of the carriage spring until the blocking pawl is released.

Each escapement pawl is controlled by at least one and lice preferably two releasing members which have staggered coupling portions cooperating with a series of selector members extending across the releasing members. The arrangement is such that, if different selector members are actuated under the control of the typewriter keys, different groups of pawls are released from the rack bar for movement in rearward direction, then engage the rack bar again, and move with the same in forward direction until the carriage is blocked after a step whose length depends on which selector member was actuated.

One embodiment of the invention comprises a set of escapement pawls, each pawl having an engaging portion cooperating with the recesses of the carriage rack, and a stop portion, the stop portions and engaging portions being spaced different distances on each pawl so that the stop portions are staggered in the direction of carriage movement a predetermined equal distance which is an integral fraction of the pitch of the rack; supporting means for supporting the pawls for movement between a normal engaged position located in a recess of the rack and a released position, and also for movement in the released position along the rack, and including blocking means, preferably a shaft supporting the pawls for turning and translatory movement, and being engaged by the stop portion leading in the forward direction of carriage movement so that the carriage is blocked; biassing means biassing the pawls to rnove rearwardly opposite to the forward direction, and into the engaged position; a set of releasing means respectively cooperating with the pawls and movable to a releasing position for moving the respective pawl to the released position; and selector means for selectively moving the releasing means to the releasing position so that corresponding selected pawls are moved to the released position and move rearward until the respective engaging portions engage a recess of the rack. Thereupon, the biassed carriage moves with the pawls forward until blocked by a selected pawl whose stop portion leads in the forward direction. In this manner the carriage moves a step whose length is between one and a selected plurality of the equal distances which the stop portions of the pawls are spaced from each other.

This predetermined distance will be hereinafter referred to as e, and is an integral fraction of the pitch t of the rack. In the preferred emobdiment of the invention three pawls are provided in the set, so that t is equal to 3e.

In the preferred embodiment of the invention, each releasing means includes a pair of first and second releasing members cooperating with the same pawl. When the first releasing member is actuated, it turns the respective pawl to the released position, and permits the pawl to move the distance e until again returning to the engaged position. When the second releasing member is actuated, the pawl is held in the released position until it has moved a distance of t+e and is then permitted to move back to the engaged position. The first and second releasing members have staggered coupling portions cooperating with a set of transverse selector members crossing the releasing members.

Releasing members which are moved by selector members to the releasing position, are locked by a locking means until the respective pawl has performed its function and is again returned by the carriage.

The selector members and the ends of the coupling portions of the releasing members are arranged so that the first selector mem'ber causes the carriage to move one step having the distance e, and the last selector member causes the carriage to move the distance 62. However, by increasing the number of releasing members, or of the escapement pawls an even greater number of diiferent carriage steps can be obtained.

In contrast to the prior art, in which selector means directly act on the escapement pawls, the present invention provides releasing means which permit the use of a smaller number of escapement pawls for obtaining the same number of different steps as can be accomplished by the prior art constructions. In accordance with the present invention, the releasing function is separated from the blocking function of the escapement pawls, and each pawl is associated with an independent releasing means, preferably including two or more releasing members.

The releasing members have releasing portions cooperating with control portions of the escapement pawls. The releasing portions of the first releasing members overlap the control portion of the respective pawls the distance e, and the releasing portions of the second releasing members overlap the control portions of the pawls the distance e+t. Consequently, the respective pawls are held in the released position by releasing members in releasing position until they have moved the length of the respective releasing portion. When the control portion of a pawl moves beyond the respective releasing portion, the pawl is free to fall into a corresponding recess of the carriage rack.

The releasing members are spring biased in a direction opposite to the carriage writing movement, and normally abut the respective pawls. The selected releasing members are locked in the releasing position until they are again returned to the normal position by the respective pawl moving with the engaged carriage in the forward writing direction.

The provision of two releasing members for each escapement pawl, wherein the second set of releasing members is spaced a full pitch distance from the respective correlated releasing members of the first set, is particularly advantageous, but only one releasing member for each pawl has to be provided for obtaining the objects of the invention.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of specific embodiments when read in connection with the accompanying drawing, in which:

FIG. 1a is a fragmentary elevation, partially in section along line 1a1a in FIG. 1b, and illustrating one embodiment of the escapement mechanism of the invention together with parts of a carriage return mechanism and of a back spacing mechanism which are not an object of the invention;

FIG. 1b is a fragmentary plan view of the embodiment of FIG. 1a;

FIG. 2 is a perspective view illustrating the main parts of the embodiment of FIG. la;

FIG. 3a is an elevation partially in section along line 3a3a in FIG. 3b, and FIG. 3b is a plan view, partially sectioned, illustrating the escapement mechanism in a first operational position, some parts being omitted for the sake of clarity;

FIG. 4a is an elevation, and FIG. 4b is a plan view, partially in section, illustrating the escapement mechanism in another operational position;

FIG. 5a is an elevation, and FIG. 5b is a plan view, partially in section, illustrating the escapement mechanism in a third operational position;

FIG. 6 is a fragmentary sectional view taken on line 6-6 in FIG. 3a; and

FIG. 7a is an elevation, and FIG. 7b is a plan view, partially in section, illustrating a modified escapement mechanism according to the present invention, parts identical with the parts illustrated in FIGS. 1a and lb being omitted for the sake of clarity.

Referring now to the drawing, and more particularly to FIGS. la andlb, the paper carriage of a typewriter h s an e p ment rack 1 and i biased by the carriage spring, not shown, to move in a forward writing direction indicated by the arrow 2.

The teeth 3 and the recesses of the rack 1 are spaced a pitch t which is equal to three predetermined distances e. Generally speaking, the distance e is an integral fraction of the pitch of rack 1. FIGS. 3a and3b show lines 34- spaced the distance e from each other, and slightly heavier lines spaced the distance I from each other.

An escapement mechanism P includes a set 4 of three escapement pawls 4 4 4 guided in slots of a comb 32 and whose engaging portions 5 5 5 which will be generally referred to as engaging portions 5, cooperate with the recesses between the teeth 3 of rack 1.

The set 4 of escapement pawls 4 4 4 is mounted on a stationary shaft 7, for turning movement into and out of the recesses between teeth 3, and also for movement in the direction of rack bar 1.

In the following description, parts of the mechanism which are respectively associated with the three pawls 4 4 4 will be referred to by a reference numeral with a corresponding subscript. The same reference numeral will be used in the specification without subscript where no distinction between the three elements of the respective set is required.

Pawls 4 have slots 6 (6 6 6 open at one end and closed at the other end by semi-circular stop portions 6' (6' 6' 6' which are spaced different distances L L L, from the tip of the respective engaging portion 5, as clearly shown in FIG. 3!). Distance L +e is distance L and distance L is distance L +e, so that the stop portions 6' 6' 6' are staggered the distance 2 from each other when engaging portions 5 register and are located in the same recess. However, since distance e is selected to be an integral fraction of the pitch 1, the stop portions 6' are also staggered the distance e from each other when some of the engaging portions 5 are located in different recesses of rack bar 1, as shown in FIGS. 4a and 5a.

Since FIG. la is a section along line la-la in FIG. lb, the foremost pawl 4 appears in dash and dot lines, and pawls 4 and 4 in solid lines. For the sake of simplicity, the reference numerals are mainly applied to those parts which have the subscript 2 and are correlated with pawl 4 Each of pawls 4 is biassed by a spring 8 engaging an arm 9 thereof for turning movement in counterclockwise direction about shaft 7 to an engaging position in which engaging portion 5 is located in a recess of rack 1, but springs 8 also urge pawls 4 to move rearwards opposite to the direction of the arrow 2 along teeth 3, which is possible when the engaging portion 5 is in a position released from the rack teeth 3.

FIG. 1a shows the engaging portions 5 5 5 of pawls 4 4 4 located in the same recess between adjacent teeth 3" and 3" of rack 1, abutting tooth 3" under the action of the carriage spring which urges the carriage to move in the forward direction of arrow 2. Consequently, the flank of tooth 3 urges pawls 4 toward the left, overcoming the weaker springs 8 so that the longest pawl 4 abuts with its semi-circular stop portion 6' on shaft 7 so that carriage movement is blocked. Stop portions 6' and 6' of the shorter pawls 4 and 4 are spaced from blocking shaft 7 the distances 2 and 2e, respectively, so that only pawl 4 blocks the carriage.

The position of pawls 4 shown in FIG. la in which all engaging portions 5 register and are located in the same recess is a basic position, but other positions are assumed by the pawls 4 in which the respective stop portions 6' of another pawl 4 abuts blocking shaft 7, and in which different engaging portions 5 are located in adjacent recesses between rack teeth 3, as will be explained hereinafter with reference to FIGS. 4a and 5a.

As shown in FIGS. 3b and 1b, pawls 4 have projecting control portions 10 (10 10 10 of which control por tion 10 is best seen in FIG. 1a. Control portions 10 have control shoulders 10, control shoulders 10 10' 10' be.

ing staggered from each other distance e so that shoulders are spaced the same distance from stop portions 6'.

Releasing means are provided for moving each pawl 4 independently of the other pawls 4 from the normal engaged position in which its engaging portion is located in a recess of rack 1 to a released position in which the respective portion 5 is located outside of the rack 1 so that spring 8 can move the respective pawl 4 rearward opposite to the direction of arrow 2.

1n the preferred embodiment of the invention, each releasing means includes two releasing members 11 and 111: so that releasing members 11 11 11 and releasing members 11a 11a and Ha are provided, as best seen in FIGS. lb and 2. Releasing members 11 and 11a have abutments 11', 11a of which an abutment 11' is shown in FIGS. 1a and 3a to abut control shoulder 10' of pawl 4 As best seen in FIG. 3b, each pawl 4 is associated with a pair of releasing members 11, 11a, and the abutments 11', 11a abut the same control shoulder 10" of the pawl 4 with which the respective pair of releasing members 11, 11a is associated.

Releasing members 11, 11a have slots 12 open to the right as viewed in the drawing and embrace shaft 7 so that all releasing members 11, 11a are guided for longitudinal and turning movement. Springs 13 and 13a are respectively connected with each pair of releasing members 11, 11a and urge the same to turn in counterclockwise direction until stops 14, 14a abut a stationary abutment 15 of the frame 50 of the machine. FIG. la shows stops 14 and 14a engaging abutment 15 under the action of the respective springs 13 and 13a. The longitudinal position of releasing members 11, 11a is determined by the staggered position of control shoulders 10' so that the semi-circular end walls of slots 12 are also staggered distances 2.

Each releasing member 11, 11a has a releasing portion 16, 16a. Releasing portions 16, 16a project over the respective control portion 10 of the associated pawl 4. As shown for releasing portions 16 and 16a, the releasing portion 16 projects over the associated control portion 10 a distance e, whereas the releasing portion 16a of releasing member 11 associated with the same control portion 10 projects over the same a distance t+e so that the ends of releasing portions 16 and 16a of each pair of releasing members are spaced the distance r.

Springs 8 are secured to a U-shaped member 52 which is mounted for turning movement on a shaft 53 and held by springs 8 in a stationary position in which a shaft 43 on the legs thereof abuts a stationary abutment 50". A member 57 is mounted on shaft 43 for turning movement and supports another member 54 for angular movement on a pair of pins 55 and 55a.

Parts 52, 53, 54, 57 belong to a back spacing mechanism S which is not an object of the invention. For the purposes of the present invention, parts 52, 54 and 57 can be assumed to be stationary. Shaft 43 is engaged by a lever 35 which is part of the back spacing mechanism S, which is not an object of the invention and which does not participate in the operation of the escapement mechanism P according to invention.

Each releasing member 11, 11a is a double-armed lever, one end of which is formed by releasing portions 16, 16a, while the other end has end faces 18, 18a. The end faces 18 are spaced the distance 2 from each other, and the end faces 18a are also spaced the distance 2 from each other. The end faces 18, 18a of each pair of releasing members 11, 11a are spaced the distance 3e which is equal to the pitch t, as best seen in FIG. 3b. All releasing members 11, 11a have the same total length.

Selector means in the form of a set of selector members 21-26 are located under the coupling portions of releasing members 11, 11a which are bounded by the end faces 18, 18a. The selector members 21-26 are spaced the distance e from each other and cross the releasing members 11, 11a as best seen in FIGS. 3b, 4b and 5b.

Each selector member 21 to 26 is independently operated under control of a type lever with which the re spective selector member 21 to 26 is associated. As will be explained hereinafter, operation of different selector members 21 to 26 causes carriage steps of different length as required for proportionate spacing, and upon operation of a typewriter key and actuation of the corresponding selector member 21 to 26, the carriage will be permitted to move a step whose length is proportionate to the dimensions of the letter or character with which the respective key is associated. The operation of selector members for proportionate spacing is well known, and not an object of the present invention.

As will be explained hereinafter, the selector member 21 is not required for controlling the carriage to make steps proportional to the characters of the keyboard and consequently selector member 21 is shown in broken lines. If provided, actuation of selector member 21 will result in movement of the carriage a distance e in the direction of the arrow 2, which is insufiicient for spacing two imprints.

By actuation of selector members 22, 23, 24, 25, 26, respectively, the carriage is controlled to move steps having the length 22, 3e, 4e, 5e, and 6e, respectively. As

explained above, the distance 3e corresponds to the pitch between the teeth of rack 1, and the distance 6e corresponds to twice the pitch t of the rack bar 1.

If it is desired to produce carriage steps of even greater length, a third releasing member is added to each pair of releasing members 11, 11a to cooperate with the control portion 10 of the respective pawl 4. The length of the releasing portion 16- of a third releasing member would be 2t+e, that is the distance 2t longer than releasing portion 16 of releasing member 11. The end face 18 of such a third releasing member would have to be located two pitch distances t to the right of the corresponding end face 18 of the respective releasing member 11. Additional selector members would have to be provided to cooperate with the third releasing members, and the slots 6 of pawls 4 would have to be made longer to prevent a slipping off of the pawls 4 when moving the distance 2t to the right. However, since carriage steps having lengths between two and six distances 2 are suflicient for perfect proportionate spacing of the imprints, the modification including third releasing members will not be further described.

Releasing members 11, 11a have locking teeth 30 at the upper edges thereof. A U-shaped locking means 48 has a locking portion 31 and two arms 48, 48" mounted for angular movement on a pair of eccentric shaft portions 7' of shaft 7 whose diameter is smaller than the diameter of shaft 7 so that locking means 48 turns about the axis of eccentric shaft portions 7' which is parallel to the axis defined by shaft 7 about which pawls 4 and releasing members 11, 11a turn. Arms 48, 48" have slots open to the right as viewed in FIG. la receiving shaft portions 7 and being held on the same by a spring 49 connecting arm 48" with member 57 which is immovable during operation of the escapement mechanism P so that spring 49 urges locking means 48 to turn in counterclockwise direction about shaft portions 7' to a position in which a sharp edge of locking portion 31 abuts a stationary stop 51 on the frame of the machine. In this normal position of the locking means 48, the locking teeth 30 of releasing members 11, 11a are spaced from locking portion 31. By turning of shaft 7, shaft portions 7' are displaced so that the position of locking means 4 8 is adjusted in relation to locking teeth 30. Turning of shaft 7 has no influenece on pawls 4 and releasing members 11, 11a.

When any one of the selector members 21 to 26 is actuated to move upwards into engagement with coupling portion 17, releasing members 11, 11a which cross the respective actuated selector member 21 to 26 are turned in clockwise direction as viewed in FIG. la so that locking teeth 30 engage the edge of locking portion 31 and turn locking means 48 in clockwise direction against the action of spring 49. The selected and locked releasing members 11, 11a are prevented from moving to the right, as viewed in FIG. 1a, under the action of springs 13, 13a.

When selected releasing members 11, 11a are turned by actuated selector members 21 to 26, the respective releasing portions 16, 16a act on control portions 10 of the associated pawls to turn the respective selected pawls 4- in clockwise direction about shaft 7, to a released position in which the recesses of rack 1 are not engaged by engaging portions of the respective selected pawls 4. Consequently, springs 8 pull the selected pawls 4 in the released position rearward opposite to the forward writing direction of the carriage.

Control portions of released pawls 4 slide under releasing portions 16, 16a of the respective releasing members 11, 11a, and when control shoulders 10" have moved beyond the same, the respective engaging portions 5 fall again into a recess under the action of springs 8. The smallest distance through which a pawl 4 can move is the distance e, and the greatest distance is the distance 22. If only releasing member 11 of a pawl 4 is selected and actuated, the respective pawl 4 will move a distance e to the right, and when the releasing member 11a of a pawl 4 is actuated, the respective pawl 4 will move a distance t-l-e rearward before falling into a recess of the rack 1. In the first case, the engaging portion 5 will fall into the next following recess, and in the second case engaging portion 5 will fall into the second following recess of the rack 1.

Since pawls 4 have a very small mass and are biassed by strong springs 8, they move very rapidly rearward when released from the rack 1 by a releasing member 11, 11a and such rearward movement takes only a few milliseconds. The heavy paper carriage with rack 1 starts moving in forward direction as indicated by arrow 2 very slowly due to its inertia so that engaging portions 5 are again located in recesses of rack bar 1 when the carriage moves forward whereby all pawls 4 are moved by the carriage in forward direction until the stop portion 6" of a leading pawl 4 abuts shaft 7.

The leading pawl 4 whose stop portion 6 blocks the carriage movement is always the pawl which, after reengagement of portions 5 in recesses of the rack bar 1, has its stop portion 6' located farthest to the left as viewed in the drawing in the direction of forward carriage movement.

Stepwise carriage movement for different distances will now be described in detail with reference to FIGS. 3a 3b, 4a, 4b, 5a and 5b. The parallel lines 34 which are spaced distances e permit an evaluation of the movements of engaging portions 5 and rack bar 1 in relation to a fixed point. The trailing flank of engaging portion 5 of pawl 4 which blocks carriage movement, is hatched in FIGS. 3b, 4b and 512.

If in the position of FIGS. 3a, 3b, a selector member 21, shown only in FIG. 1a, would be actuated, engaging portion 5 would be moved out of the recess in rack bar 1 by releasing portion 16, so that a carriage would start movement to the left. Engaging portion 5 of the second pawl 4 would be taken along by the rack bar 1 and engage shaft 7 after movement of the carriage a distance e so that the carriage would be stopped. The resulting position would correspond to the position of FIGS. 5a and 5b, except that teeth 3', 3" and 3" would be displaced one pitch distance r to the right. In this position, pawl 4 blocks carriage movement by engaging with its stop portion 6' blocking shaft 7, while stop portion 6' is spaced one distance e, and stop portion 6' is spaced two distances 2 from shaft 7, and in which engaging portion 5 of the longest pawl 4 engages the next rearwardly located recess of rack bar 1 located forwardly of tooth 3' which would be located one pitch distance to the right as viewed in FIG. 5a. The carriage would have moved one step e which is not required for proportionate spacing of the characters printed by a typewriter, so that selector member 21 can be omitted.

If, starting from the position of FIGS. 3a and 3b, selector member 22 is actuated, for causing a carriage step having the length 2e, releasing members 11 and 11 are operated, and pawls 4 and 4 turned to the released position, while releasing members 11 and 11 are locked by engagement of locking teeth 30 by locking portion 31. The relased pawls 4 and 4 fall into the next rearwardly located recess in front of tooth 3' while the still engaged pawl 4 is taken along by the carriage in forward direction until its stop portion 6' abuts shaft 7 so that pawl 4 blocks carriage movement by engagement of tooth 3.

Pawls 4 are now in the position shown in FIGS. 4a and 4b.

When starting from the position of FIGS. 3a and 3b selector member 23 is actuated, all three releasing members 11 11 11 are operated, and all three pawls 4 4 4 are moved to the released position. Engaging portions 5 fall, after moving a distance corresponding to the length of releasing portions 16, into the next following recess of rack bar 1, abutting tooth 3", so that the pawls 4 are moved by the carriage in forward direction until they are in a position corresponding to the position of FIGS. 3a and 3b, however with teeth 3', 3" and 3" shifted the pitch t to the left. Pawl 4 blocks the carriage movement and the carriage has moved a distance I or 3e.

If, starting from the position of FIGS. 3a and 31:, selector member 24 is actuated, the releasing members 11 of all pawls 4, and also releasing member 1141 are turned and locked with locking teeth 30 on locking portion 31. Pawls 4 and 4 fall into the next following recess of rack bar 1 located forwardly of tooth 3' so that stop portions 6' and 6' are spaced four and five distances 2, respectively, from shaft 7, disregarding the carriage movement in forward direction which has started in the meantime. Pawl 4 cannot fall at the same time into the recess, since the respective releasing portion 16a of the operated releasing member 11a holds pawl 4 until the same has passed tooth 3 so that engaging portion 5 falls into the recess rearwardly of tooth 3 and abuts the leading flank of the next following rearwardly located tooth of rack 1. Pawl 4 is moved by the paper carriage until after a movement of the paper carriage of four distances e, stop portion 6' of pawl 4 abuts shaft 7 in the position of FIG. 5. As noted above, this position corresponds to the movement of the carriage a distance 2, except for the different position of the carriage and of the displacement of teeth 3, 3", 3" for the distance 1 since the distance 4e is t+e.

Starting from the position of FIGS. 3a and 3b, actuation of selector member 25 will cause operation of releasing members 11 11 11 and also of releasing members 11a and 11a;. The paper carriage moves five steps e, and engaging portion 5 engages the recess forwardly of tooth 3, while engaging portions 5 and 5 controlled by re leasing members 11a 1111 fall in the second next recess of rack 1 behind tooth 3' since the longer releasing portions 16a, prevent an earlier return of the respective pawls 4 to the engaged position.

If the selector member 26 is actuated, all six releasing members 11 and 11a are operated, all pawls 4 are turned, and the long releasing portions 16a permit return of the pawls 4 to the engaged position located in the second rearwardly located recess, corresponding to a carriage step having the length of six distances e until stop portion 6' of pawl 4 engages shaft 7 to block the carriage after a movement of the carriage a distance 2t, corresponding again to the position of FIG. 3a, with teeth 3, 3", 3" displaced two pitch distances t to the left.

While all operations have been described starting from the position of FIGS. 3a and 3b, any of the positions illustrated in FIGS. 4a, 4b and 5a, 5b can be used as starting position, and the carriage will move distances 2e to 6e, depending on the actuation of selector members 22 to 26.

The construction of the invention can be modified by providing more than three pawls 4, in which event the distance e is the distance tdivided by the number of pawls. On the other hand, only two pawls 4 and 4 can be provided in which event the pitch t is equal to 2e. Three releasing members are then required for each pawl 4, as explained above, and it would still be possible to obtain carriage steps having a length between 2e and 6e.

Since releasing members 11, 11a do not have to sustain substantial forces, the releasing members 11, 11a can be made lighter and thinner than pawls 4 which have to block carriage movement. As is particularly apparent from FIG. 6, six releasing members 11, 11a and three pawls 4 can be easily provided adjacent each other across the thickness of rack bar 1. In the present invention, two releasing members 11, 11a are associated with each pawl 4 and obtain steps having a length between 2 and be. In known escapement mechanisms, seven pawls are required for obtaining six different steps of the carriage, and the pitch t is equal to seven distances e. Consequently, the construction of the present invention permits the use of less than half the number of pawls required by the prior art for producing six different steps of the carriage. The number of pawls substantially determines the thickness of rack bar :1, and the number of the releasing members 11, 11a is of lesser importance, since they are thinner.

FIGS. 7a and 7b illustrate a modification of the construction of the pawls 104 and releasing members 111, 11:1a. Pawls 104 are illustrated in a position in which all engaging portions 105 are located in the same recess. Instead of the control portions of the above described embodiment of FIG. 1a, each pawl 104 has a laterally projecting control pin 110, all control pins 110 being spaced the same distance from the respective engaging portions 105 so that pins 110 register when engaging portions 105 register. The distances between engaging portions 105 and stop portions 106' are different, as best seen in FIG. 7b.

Each control pin 110 is embraced by an open slot 111', ll la respectively of releasing members 111, 111a whose left slot end portions 111", 111a", superimposed in FIG. 7a, abut pins 110. Above slots 111, 111a releasing members 111, 111a have releasing portions 116, =116a, respectively, which project from the center of pins 110 in rearward direction a distance e, and a distance t+e respectively. The lower edges of slots :111', 111a guide releasing members 111, 111a depending on the angular position of the respective pawl 104, and substitute for the abutment of arms 14 on the stop face 15 in the embodiment of FIG. 1a by limiting the turning movement under the action of springs 113, 113a in counterclockwise direction. The upper edges of slots 111', 111a guide pawls 104, if one of the selector members 22 to 26- is actuated, for movement in rearward direction, until pins :110 slide off the end faces at the right of releasing portions 116,

11611 and engage rack 1.

'When one of releasing members 111 .is actuated pin 110 takes along releasing member 111a since it is located in its slot 111a. However, since the respective releasing member '111a is not raised by the selector member 22 and 23 and its left end is free and not locked by locking portion 31, pin 110 of the released pawl 104 slides off releasing portion 116 of the operated releasing member 111, and takes along the freely movable releasing member 111a when falling with its engaging portion 105 into a recess of rack 3.

A guide portion 111" and 111a on releasing members 111 and 111a, respectively, located at the lower end of the respective slots 111', 111a assists the movement of engaging portion 105 into a recess of rack 1, when the releasing member 111a is operated. In this manner,

the return of the pawls 104 to the engaged position is more rapidly efiected.

In the embodiment of FIGS. 7a and 7b, pins 110 act on the edges of slots 111', 111a while moving in forward direction with engaging portions engaged by the teeth of rack '1 so that the displaced and locked releasing members 111, 111a are moved out of engagement with the locking portion 31 and return to the normal position by the action of springs 113 and 113a.

In the embodiment of-FIGS. la and lb, the engaged pawls 4 which are moved to the left by the carriage moving forward in the direction of the arrow 2, engage with control portions 10 the slanted edges of the releasing portions 16 and 16a of releasing members 11, '11a in the releasing position, and turn the same back to the normal position in which locking teeth 30 are separated from locking portion 31.

What is claimed as new and desired to be secured by Letters Patent is:

1. An escapement mechanism for a carriage having a rack with teeth and recesses spaced a predetermined pitch and being biased to move in a forward writing direction, comprising, in combination, a set of escapement pawls, each pawl having an engaging portion cooperating with said recesses and a stop portion, said stop portions and engaging portions being spaced different distances on each pa'wl so that said stop portions are staggered in said direction a predetermined equal distance which is an integral fraction of said pitch; supporting means supporting said pawls for movement between a normal engaged position in which the respective engaging portion is located in one of said recesses, and a released position, and also for individual movement in said released position along said rack, and including blocking means engaged by the stop portion leading in said forward direction under the action of said biased carriage so that forward carriage movement is blocked; biasing means biasing said pawls to move rearward opposite to said forward direction, and into said engaged position; a set of releasing means respectively cooperating with said set of pawls, each releasing means having a normal position and a releasing position for moving the respective pawl to said released position; selector means for selectively moving said releasing means to said releasing position so that corresponding selected pawls are moved to said released position and move rearward until the respective engaging portions engage a recess whereupon said biased carriage moves with the engaged pawls forward until blocked by the selected pa-wl whose stop portion leads in said forward direction, whereby said carriage means moves a step whose length is between one and a selected plurality of .said predetermined equal distances; and locking means for locking selected releasing means in said releasing position, said releasing means being engaged by said pawls dui-ing movement of the same in said engaged position with said carriage means in said forward direction, so that said releasing means is separated from said locking means and returns to said normal position.

2. An escapement mechanism for a carriage having a rack withteeth and recesses spaced a predetermined pitch and being biased to move in a forward writing direction, comprising, in combination, a set of escapement pawls, each pawl having an engaging portion cooperating with said recesses and a stop portion, said stop portions and engaging portions being spaced different distances on each pawl so that said stop portions are staggered in said direction a predetermined equal distance which is an integral fraction of said pitch; supporting means supporting said pawls for movement between a normal engaged position in which the respective engaging portion is located in one of said recesses, and a released position, and also for individual movement in said released position along said rack, and including blocking means engaged by the stop portion leading in said forward direction under the action of said biased carriage so that forward carriage movement is blocked; biassing means biassing said pawls to move rearward opposite to said forward direction, and into said engaged position; a set of releasing means respectively cooperating with said set of pawls, each releasing means having a normal position, and a releasing position for moving the respective pawl to said released position, each releasing means including a pair of first and second releasing members, each pair of releasing members cooperating with one of said pawls, said first and second releasing members having first and second releasing portions cooperating with the respective pawl, said first and second releasing portions of each pair of releasing members being spaced said pitch from each other, said first releasing portions of said first releasing members being staggered said predetermined distance from each other, and said second releasing portions of said second releasing members being staggered said predetermined distance from each other; and selector means for selectively moving said first and second releasing members to said releasing position so that corresponding selected pawls are moved to said released position and move rearward until the respective engaging portions engage a recess whereupon said biassed carriage moves with the engaged pawls forward until blocked by the selected pawl whose stop portion leads in said forward direction, whereby said carriage means moves a step whose length is between one and a selected plurality of said predetermined equal distances.

3. An escapement mechanism according to claim 2 wherein said first and second releasing members have first and second coupling portions; wherein said first and second coupling portions of each pair of first and second releasing members are spaced said pitch; wherein said first coupling portions of said first releasing members are spaced from each other said predetermined distance; wherein said coupling portions of said second releasing members are spaced from each other said predetermined distance; and wherein said selector means include a plurality of selector members extending across said first and second releasing members, said selector members being spaced from each other said predetermined distance, and being independently movable to an actuated position engaging corresponding coupling portions of selected releasing members so that by selective operation of said selector members selected releasing members are moved to said releasing position for moving corresponding selected pawls to said released position.

4. An escapement mechanism according to claim 3 wherein said blocking means include a stationary shaft; and wherein said releasing members and said escapement pawls are mounted on said shaft for turning movement and translatory movement; including spring means for urging said first and second releasing members to abut the respective correlated pawls in said normal position; and locking means for locking said releasing members in said releasing position against movement by said spring means.

5. An escapement mechanism according to claim 4, wherein said locking means is a U-shaped member having arms mounted for turning movement on said shaft, and a locking portion connecting said arms, said releasing members having locking portions, respectively, cooperating with said locking portion in said releasing position of said releasing members.

6. An escapement mechanism according to claim 5, wherein said shaft has eccentric shaft portions supporting said arms of said blocking member for turning movement; and wherein said shaft is turnable with said shaft portions to adjust the position of said locking member in relation to said releasing members.

7. An escapement mechanism for a carriage having a rack with teeth and recesses spaced a predetermined pitch and being biassed to move in a forward Writing direction, comprising, in combination, a set of escapement pawls, each pawl having an engaging portion cooperating and engaging portions being spaced different distances 12 with said recesses and a stop portion, said stop portions on each pawl so that said stop portions are staggered in said direction a predetermined equal distance which is an integral fraction of said pitch; supporting means supporting said pawls for movement between a normal engaged position in which the respective engaging portion is located in one of said recesses, and a released position, and also for individual movement in said released position along said rack, and including blocking means engaged by the stop portion leading in said forward direction under the action of said biassed carriage so that forward carriage movement is blocked; biassing means biassing said pawls to move in a rearward direction opposite to said forward direction and into said engaged position; a set of releasing means respectively cooperating with said set of pawls, each releasing means being mounted on said supporting means for turning movement between a normal position and a releasing position for moving the respective pawl to said released position, and for translatory movement along said rack, said releasing means having coupling portions staggered said predetermined distance in said rearward direction; spring means for urging said releasing means to move in said rearward direction and to assume said normal position; stop means for limiting movement of said releasing means in said normal position; and selector means including a set of selector members extending parallel to each other across said coupling portions and being spaced from each other said predetermined distance so that actuation of any selector member causes engagement of the same with said coupling portion of an associated releasing means for moving the latter to said releasing position so that corresponding selected pawls are moved to said released position and move rearward until the respective engaging portions engage a recess of said rack whereupon said biassed carriage moves with the engaged pawls forward until blocked by the selected pawl Whose stop portion leads in said forward direction, whereby said carriage means moves a step whose length is between one and a selected plurality of said predetermined equal distances.

8. An escapement mechanism according to claim 7, wherein each of said pawls has a control portion, and each of said releasing means has a releasing portion cooperating with said control portion of the respective pawl, said releasing portions projecting over said control portions said predetermined distance so that each pawl is prevented from moving to said engaged position while said control portion thereof is in engagement with said releasing portion of the respective releasing member in said releasing position.

9. An escapement mechanism according to claim 7, wherein each releasing means includes a releasing member mounted on said supporting means for turning movement between said normal and releasnig positions; wherein each releasing member includes a releasing portion, and each pawl includes a control portion, said releasing portions of said releasing members projecting in rearward direction of carriage movement said predetermined distances, respectively, over said control portions; and including locking means for locking said releasing members in said releasing position.

10. An escapement mechanism according to claim 7 wherein said set of escapement pawls consists of a given number of pawls; and wherein said pitch is equal to said predetermined distance multiplied by said number.

11. An escapement mechanism for a carriage having a rack with teeth and recesses spaced a predetermined pitch and being biassed to move in a forward Writing direction, comprising, in combination, a set of escapement pawls, each pawl having an engaging portion cooperating with said recesses and a stop portion, said pawls having slots bounded by said stop portions, said stop portions and engaging portions being spaced different distances on each pawl so that said stop portions are staggered in said di rection a predetermined equal distance which is an integral fraction of said pitch, said pawls having control portions staggered from each other said predetermined distance; supporting means supporting said pawls for movement between a normal engaged position in which the respective engaging portion is located in one of said recesses, and a released position, and also for individual movement in said released position along said rack, and including blocking means including a shaft passing through said slots of said pawls for supporting the same for turning and translatory movement and being engaged by the stop portion leading in said forward direction under the action of said biassed carriage so that forward carriage movement is blocked; biassing means biassing said pawls to move in a rearward direction opposite to said forward direction, and into said engaged position; a set of releasing means respectively cooperating with said set of pawls and having slots through which said shaft passes for supporting said releasing means for turning and translatory movement, each releasing means having a normal position, and a releasing position for moving the respective pawl to said released position, said releasing means having releasing portions staggered from each other said predetermined distance and respectively engaging said control portions of said pawls; spring means urging said releasing means with said releasing portions into abutment with said control portions, respectively; locking means for locking said releasing means in said releasing positions and being released by said pawls, respectively, during return of the same in said forward direction with said carriage; means for limiting movement of said releasing means in said normal position under the action of said spring means; and selector means for selectively moving said releasing means to said releasing position so that corresponding selected pawls are moved to said released position and move rearward until the respective engaging portions engage a recess whereupon said biassed carriage moves with the engaged pawls forward until blocked by the selected pawl whose stop portion leads in said forward direction, whereby said carriage means moves a step whose length is between one and a selected plurality of said predetermined equal distances.

12. An escapement mechanism for a carriage having a rack with teeth and recesses spaced a predetermined pitch and being biassed to move in a forward writing direction, comprising, in combination, a set of escapement pawls, each pawl having an engaging portion cooperating with said recesses and a stop portion, said stop portions and engaging portions being spaced different distances on each pawl so that said stop portions are staggered in said direction a predetermined equal distance which is an integral fraction of said pitch; supporting means supporting said pawls for movement between a normal engaged position in which the respective engaging portion is located in one of said recesses, and a released position, and also for individual movement in said released position along said rack, and including blocking means engaged by the stop portion leading in said forward direction under the action of said biassed carriage so that forward carriage movement is blocked; biassing means biassing said pawls to move in a rearward direction opposite to said forward direction, and into said engaged position; a set of releasing means respectively cooperating with said set of pawls, respectively, and having locking teeth, each releasing means having a normal position, and a releasing position for moving the respective pawl to said released position; a locking means including a locking portion having a sharp edge extending across said releasing means, said locking teeth being engaged by said edge of said locking portion in said releasing position of said releasing means; spring means biassing said releasing means to move to said normal position when disengaged from said locking means, said pawls in said engaged position moving forward with said rack disengaging the respective releasing means from said locking portion; and selector means for selectively moving said releasing means to said releasing position so that corresponding selected pawls are moved to said released position and move rearward until the respective engaging portions engage a recess whereupon said biassed carriage moves with the engaged pawls forward until blocked by the selected pawl =whose stop portion leads in said forward direction, whereby said carriage means moves a step whose length is between one and a selected plurality of said predetermined equal distances.

13. An escapement mechanism for a carriage having a rack with teeth and recesses spaced a predetermined pitch and being biassed to move in a forward writing direction, comprising, in combination, a set of escapement pawls, each pawl having an engaging portion cooperating with said recesses and a stop portion, said stop portions and engaging portions being spaced different distances on each pawl so that said stop portions are staggered in said direction a predetermined equal distance which is an integral fraction of said pitch; supporting means supporting said pawls for movement between a normal engaged position in which the respective engaging portion is located in one of said recesses, and a released position, and also for individual movement in said released position along'said rack, and including blocking means engaged by the stop portion leading in said forward direction under the action of said biassed carriage so that forward carriage movement is blocked, said blocking means including a shaft supporting said pawls for turning and translatory movement; biassing means biassing said pawls to move a rearward direction opposite to said forward direction, and into said engaged position; a set of releasing means respectively cooperating with said set of pawls, each releasing means having a normal position, and a releasing position for moving the respective pawl to said released position, said releasing means abutting said pawls, respectively, when the latter are in said engaged position and said releasing means are in said normal position; spring means urging said releasing means into abutment with said pawls, respectively, and to move in said rearward direction; locking means for locking selected releasing means in said releasing position; said shaft of said blocking means having eccentric shaft portions supporting said locking means for turning movement and being turnable for adjusting the position of said locking means in relation to said releasing means; and selector means for selectively moving said releasing means to said releasing position so that corresponding selected pawls are moved to said released position and move rearward until the respective engaging portions engage a recess whereupon said biassed carriage moves with the engaged pawls forward until blocked by the selected pawl whose stop portion leads in said forward direction, whereby said carriage means moves a step whose length is between one and a selected plurality of said predetermined equal distances.

14. An escapement mechanism for a carriage having a rack with teeth and recesses spaced a predetermined pitch and being biassed to move in a forward writing direction, comprising, in combination, a set of escapement pawls, each pawl having an engaging portion cooperating with said recesses and a stop portion, said stop portions and engaging portions being spaced different distances on each pawl so that said stop portions are staggered in said direction a predetermined equal distance which is an integral fraction of said pitch, said pawls having contrtol portions staggered said predetermined distance in the direction of carriage movement; supporting means supporting said pawls for movement :between a normal engaged position in which the respective engaging portion is located in one of said recesses, and a released position, and also for movement in said released position along said rack, and including blocking means including a shaft supporting said pawls for turning and translatory movement and being engaged by the stop portion leading in said forward direction under the action of said biassed carriage so that forward carriage movement is blocked; biassing means biassing said pawls to move in a rearward direction opposite to said forward direction, and into said engaged position; a set of releasing means respectively cooperating With said set of pawls, each releasing means having a normal position, and a releasing position for moving the respective pawl to said released position, each releasing means including a pair of first and second releasing members, said first and second releasing members having first and second releasing portions, a pair of first and second releasing portions projecting in said rearward direction over the control portion of the respective pawl, said first releasing portions being spaced from each other said predetermined distance, said second releasing portions being spaced from each other said predetermined distance, and said first and second releasing portions of each pair of first and second releasing members being spaced from each other said pitch, said first and second releasing members having first and second coupling portions, said first couplin-g portions being staggered relative to each other said predetermined distance, said second coupling portions being staggered relative to each other said predetermined distance, and said first and second coupling portions of each pair of first and second releasing members being staggered relative to each other said pitch; and selector means for selectively moving said releasing means to said releasing position so that corresponding selected pawls are moved to said released position and move rearward until the respective engaging portions engage a recess whereupon said biassed carriage moves with the engaged pawls forward until blocked by the selected pawl whose stop portion leads in said forward direction whereby said carriage means moves a step whose length is between one and a selected plurality of said predetermined equal distances, said selector means including a set of selector members cooperating with said coupling portions and being spaced from each other said predetermined distance so that movement of any selector member into engagement 'wi-h corresponding associated coupling portions of selected releasing members causes movement of the same to said releasing position whereby the associated selected pawls are moved to said released position and remain in the same until said control portion has passed in rearward direction beyond the associated re leasing portions of selected releasing members in said releasing position.

15. An escapement mechanism according to claim 14 and including locking means for locking said selected releasing members in said releasing position, said releasing portions of locked releasing members being engaged by the control portions of the respective associated pawls when the same are in said engaged position and move forward with said carriage whereby said releasing members are unlocked from said locking means.

16. An escapement mechanism according to claim 14 wherein said set of escapement pawls includes three escapement pawls; and wherein said predetermined distance is one third of said pitch.

17. An escapement mechanism according to claim 14 wherein said control portions are rectangular projections having forwardly located shoulders staggered said predetermined distance; and wherein said releasing members have abutments abutting said shoulders in said normal position of said releasing members; and wherein said releasing portions project over said control portions adjacent said control shoulders.

18. An escapement mechanism according to claim 14 wherein said control portion is a pin laterally projecting from each pawl; and wherein each of said first and second releasing members is formed with a slot in which the pin of the associated pawl is located, said slot being bounded on one side by said releasing portion of the respective releasing member.

References Cited UNITED STATES PATENTS 2,385,035 9/1945 Smathers 197-84 2,547,449 4/ 1951 Dodge 197-84 2,753,973 7/1956 Dodge et al. 197-84 2,818,154 12/1957 Letterman et al. 197-84 2,862,595 12/1958 Toggenburger 197-84 2,872,015 2/1959 Toggenburger 197-91 2,905,303 9/1959 Palmer et al 197-84 2,972,401 2/1961 Salto 197-84 3,288,262 11/1966 Salto 197-84 3,288,263 11/1966 Salto 197-84 X ERNEST T. WRIGHT, J 11,, Primary Examiner US. Cl. X.R. 197-91

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