US3827543A

US3827543A - Typewriting mechanism for a typewriter machine

Info

Publication number: US3827543A
Application number: US00255697A
Authority: US
Inventors: R Kawano; M Otsuka; K Goda; H Yamakawa
Original assignee: Kurosawa Tele Communications Ltd
Current assignee: Kurosawa Tele Communications Ltd
Priority date: 1972-05-22
Filing date: 1972-05-22
Publication date: 1974-08-06
Anticipated expiration: 1991-08-06

Abstract

A typewriting mechanism for a typewriter machine in which mechanism a swingable hammer bracket supporting a typewheel having a number of types formed on the surface of the typewheel, is driven by a single rotary magnet without being disconnected from a type-character selecting mechanism so that the typewheel strikes against the platen and a type-character on the surface of the typewheel is printed on the typewriter paper around the platen. The single rotary magnet also actuates a locking mechanism of the typewheel and a lever for driving an ink ribbon feed mechanism.

Description

Aug. 6, 1974 Decker et a1. 197/55 m of the type- 3,344,378 9/1967 Wilhelmson 3,405,794 10/1968 Means..,............... 3,461,996 8/1969 3,674,126 7/1972 Primary ExaminerRobert E. Pulfrey Assistant ExaminerR. T. Rader Attorney, Agent, or Firm-Maleson, Kimmelman and Ratner [57] ABSTRACT A typewriting mechanism for a typewriter machine in which mechanism a swingable hammer bracket supporting a typewheel having a number of types formed on the surface of the typewheel, is driven by a single rotary magnet without being disconnected from a type-character selecting mechanism so that the typewheel strikes against the platen and a type-character on the surface of the typewheel is printed on the typewriter paper around the platen. The single rotary magnet also actuates a locking mechanis wheel and a lever for driving an ink ribbon feed anism.

yoshi all of Japan Communications Tokyo, Japan 197/55, 335/272 B41j l/32 197/55, 18, 52, 16; 335/272 TYPEWRITING MECHANISM FOR A TYPEWRITER MACHINE [75] lnventors: Reijiro Kawano; Kazuhiro God both of Kawasaki; Hiroshi Yamakawa, Tokyo; Masa Otsuka, Kawasaki,

Assignee: Kurosawa Tel- Limited,

Filed: May 22,

Appl. No.: 255,697

Field of Search References Cited UNITED STATES PATEN Unite States Patent Kawano et al. I

mech

8 Claims, 23 Drawing Figures Ellner Segawa et a1. 966 Burchfield PATENTEBMIB m n I 3.827. 543

sum 03 0f 10 PAIENIEBMIB B1914 :3. 82 7. 543

sum ouur 1o i PAIENIEMHB 6 3.827.543

sum as or 10 I w 3 TORQUE OF THE I HAMMER MAGNET y i- M A //TORQUE OF SPRING /PRINTING POINT v 1 v I 9| 2 e0 ANGLE PAIENIEM B 3 am 543 saw 07 or 10 mramaowc 6m "3.827.543

sum as one,

TORQUE ANGLE Fig. I40; Fig, [4b

mamcuwc m" 3.827. 543

sum *oaar 10- PATENTEB 5 I974 AMOUNT OF OPERATION sum 5 mar 10 Fig. 7

RETURN OF FEED PAWL OF THE RIBBON FEED MECHANISM REBBON FEED OPERATION TYRE CHARACT ER SELECTING PRINTING OPERATION LOCKING OPERATION RELEASE OF LOCKING TIME \PRINTING MOMENT ONE COMPLETE CYCLE OF THE TYPEWR ITI NG ORERATI ON TYPEWRITING MECHANISM FOR A TYPEWRITER MACHINE In some conventional typewriting mechanisms of a typewriter machine employing a system such as a typewheel or type cylinder having types formed on the surface thereof, directly strikes against the platen, the printing motion of the typewheel is produced through the operation of cams mounted on a hammer shaft driven through a clutch mechanism and the restoring motion of the typewheel after completion of the printing of a type-character is carried out by a restoring spring, or alternatively the printing motion is produced by a spring force and the restoring motion is carried out through the operation of a cam mechanism.

However, these conventional mechanisms are accompanied by such drawbacks that not only is the top speed of the typewriting operation restricted but also, the typewriting mechanism is very complicated and is accompanied by high production cost and extremely high operation noise.

In some other conventional typewriting mechansisms, the printing motion of the typewheel is produced by an absorption type magnet such as a plunger type magnet.

In this mechanism, there are the advantages that the arrangement of the mechanism is relatively simple and control of the hammering action can be easily carried out. However, there are such serious drawbacks that the restoring action of the magnet takes a long time due to its poor stroke to torque characteristics and also, the initial torque of the magnet is very small and as a result, high-speed typewriting operation, now in great demand, can not be achieved.

Furthermore in this mechanism, not only does the change of excitation time of the magnet produce change of printing pressure but also, simultaneous em ployment of a particular free-flight mechanism is required to form a free-flight region in the printing motion of the typewheel and moreover, impact sound produced by the absorbing motion of the plunger magnet, adds undesirable noise to the sound of the printing operation.

Therefore an object of the present invention is to eliminate the above-mentioned drawbacks of the conventional typewriting mechanism of a typewriter machine.

Another object of the present invention is to provide a typewriting mechanism for a typewriter machine which can achieve high-speed typewriting operation.

A further object of the present invention is to provide a typewriting mechanism of a typewriter machine which can reduce operating noise.

Another object of the present invention is to provide a high-speed typewriting mechanism for a typewriter machine whereby the typewriting operation sequence including locking operation of the typewheel after completion of a type-character selection, printing operation, and ribbon feeding operation can be continuously carried out by employing a single driving source.

A still further object of the present invention is to provide a rotary type magnet which can be used for said driving source of the typewriting mechanism of a typewriter machine.

The foregoing and other objects, features and advantages of the present invention will be apparent from the ensuing description with reference to the accompanying drawings illustrating a preferred embodiment of the present invention wherein:

FIG. 1 is an outside view of the typewriter machine employing a type carrier provided with the typewriting mechanism of the present invention;

FIG. 2 is a plan view of the type carrier provided with the typewriting mechanism of the present invention;

FIGS. 3 and 4 are opposite side views of FIG. 2;

FIG. 5 is a schematically perspective view of the mechanism for selecting a type-character;

FIG. 6 is a schematically perspective view for illustrating the mechanism for locking the typewheel;

FIG. 7 is a schematical side view for illustrating the printing operation of the typewriting mechanism of the present invention;

FIG. 8 is a partial view illustrating the operation of the toggle spring employed in the typewriting mechanism of the present invention;

FIG. 9 is a schematic view illustrating the positional relationship between the rotor and stator of the rotary magnet used in the typewriting mechanism of the present invention;

FIG. 10 is a diagram showing the torque characteristics curve of the rotary magnet according to FIG. 9;

FIG. 11 is a disassembled perspective view of an example of the rotary magnet;

FIG. 12a, b, c and d are diagrams illustrating the positional relationship of the rotor and stator of the rotary magnet and the torque characteristic curves;

FIG. 13a and b are diagrams illustrating another positional relationship of the rotor and stator of the rotary magnet and the torque characteristics curve;

FIG. 14a and b are diagrams illustrating still another positional relationship of the rotor and stator of the rotary magnet and the torque characteristics;

FIG. 15 is a partial plan view illustrating the mechanism for feeding an ink ribbon;

FIG. 16 is a partial side view of FIG. 15;

FIG. 17 is a diagram illustrating the operation sequence carried out by the typewriting mechanism of the present invention.

FIG. 1 is an outside view of a typewriter machine provided with a type carrier 11 having a typewriting mechanism according to the present invention.

The type carrier 11 carries out carriage spacing movement in the directions shown by the arrow "8 along a conventional platen 13 when the carrier 11 is required for typewriting operation through an ink ribbon (not shown) on a typewriting paper 15 borne on the platen 13.

Reference numeral 17 shows a keyboard carrying thereon a number of keys, tabulation bar and a space bar, etc.

Reference numeral 19 shows a part of the driving mechanism of the platen 13 and other parts.

Referringto FIG. 2 to FIG. 4 illustrating a detailed assembly of the type carrier 11, there is shown a hammer bracket 21 supporting a type wheel 31, a rotary type hammer magnet 23, a gear box 25, a ribbon feedmechanism 27 and

carrier frames

29a, 29b arranged at the opposite sides of the bracket 21.

The box-like hammer bracket 21 is swingablyassembled to the

carrier frame

29a, 29b via pivots 33, and also, the hammer bracket 11 is combined with a shaft 23a of a hammer magnet'23 by means of a lever arm 35 via a locking lever 37 and as a result, according to the rotary action of the output shaft 23a of hammer magnet 23 upon being energized via an electrical lead 24, the hammer bracket 21 performs the printing operation as later described in detail. I

At the rear portion of hammer bracket 21, the gear box 25 is arranged stationary with respect to

carrier frames

29a, 29b and through the gear box 25,

shafts

39 and 41 are disposed for selecting a required typecharacter from a number of type-characters formed on the surface of a typewheel 31, that is, the rotation of

respective shafts

39 and 41 causes a later described typecharacter selecting operation so that the required character on the typewheel 31 is located at a selected position where the character can be printed.

At the rear

most frames

29a and 29b, a pair of

roller members

45, 47 are disposed so as to be able to slide along a stationary guide rail 49.

Also, at the

foremost frames

29a, 29b, a pair of

guide bushes

51, 53 are disposed through which a stationary guide shaft 55 transversely extends.

The guide rail 49 and the guide shaft 55 allow the type carrier 11 to shift in to and fro transverse directions along them.

A spacing belt 57 is fixed to a bracket member 59 rigidly combined with

frames

29a, 29b so that the type carrier 11 is shifted to an arbitrarily selected printing position by shifting forces in the to and fro transverse directions given via the belt 57.

The ribbon feed-mechanism 27 is disposed at an upper portion of

frames

29a, 29b of type carrier 11 so as to provide a feeding force to carry out the ink ribbon feed operation.

Now the operation of the typewriting mechanism according tothe present invention will be described in more detail in accordance with the operation sequence from the selection of a certain type to the completion of the typing of that type.

FIG. schematically illustrates the mechanism for selecting a type character to be printed from a number of type characters arranged on the surface of typewheel 31 in the vertical and circumferential directions.

A shaft 65 rotatably mounted on hammer bracket 21 via a bearing 66 and supporting typewheel 31 which is slidably mounted on the shaft 65 operates as a type character selection shaft in the circumferential direction which may be called circumferential typewheel selection shaft.

Numeral 67 is a rack member having rack gear teeth 69 formed at the front edge thereof and vertically slidably mounted on hammer bracket 21 while being rotatably associated with typewheel 31. This rack member 67 operates as a type-character selection element in the vertical direction.

Numeral 73 is a spiral gear rigidly fixed to the lower portion ofcircumferential typewheel selection shaft 65. The elongated shaft 39 transmits the action of the circumferential type-character selection to the typewheel 3 from the outside and also, the elongated shaft 41 transmits the other action of the vertical type-character selection to the typewheel 31 from the outside.

Shafts

39 and 41 have rectangular shaped cross-sections. Numeral 75 is a spiral gear housed in the gear box 25 and rigidly mounted on shaft 39 so that the spiral gear 75 together with shaft 39 are capable of sliding in accordance with the carriage spacing movement of hammer bracket 21. Numeral 77 is a spur gear fixedly mounted on shaft 41 so that spur gear 77 together with shaft 41 are capable of sliding also in accordance with the carriage spacing movement of hammer bracket 21. Numeral 79 is an idler gear concentrically and rotatably mounted on a flange (not shown) of spiral gear 75 while being in a meshing engagement with spur gear 77 and rack gear teeth 69 of rack member 69. That is gear 79 receives its driving force from gear 77.

As will be understood from the foregoing and later description, hammer bracket 21 is capable of swinging about pivots 33 with respect to

carrier frames

29a and 29b (not shown) so as to carry out the printing operation. A line A-A passing through the center of pivots 33 in the axis of the above-mentioned swinging movement of hammer bracket 21.

According to one of features of the present invention, spiral gear 75 and idler gear 79 keep a meshing engagement with spiral gear 73 and rack gear teeth 69 of rack member 67 respectively on the line A-A'. In other words, the respective meshing points always lie on the line A-A' about which hammer bracket 21 swings to carry out the printing action.

In this case, a suitable amount of backlash may be provided at the respective meshing points so that interference between respective gears may be avoided when hammer bracket 21 starts to swing for carrying out the printing action.

In the above arrangement of a type-character selection mechanism, when a signal which commands the selection of a certain typecharacter, is given to both

shafts

39 and 41, both

shafts

39 and 41 rotate to the preselected amount of rotation required for selecting the certain type-character on typewheel 31 and the rotational movement of shaft 39 is transmitted to shaft 65 through the meshing engagement of spiral gears 75 and 73 so as to effectuate the circumferential typewheel selection while the rotational movement of shaft 41 is simultaneously transmitted to rack member 65 through the meshing engagement of

gears

77 and 79 and rack gear teeth 69 so as to effectuate the vertical typewheel selection. That is to say, typewheel 31 is positioned to a predetermined printing position where a selected type on the surface thereof can be printed on a typewriter paper (not shown) upon swinging of hammer bracket 21 about pivots 33.

According to the above arrangement wherein the meshing points of the gears for transmitting the typecharacter selecting action always correctly lie on the axis about which hammer bracket 21 swings to carry out the printing action, it is not necessary to disengage the type-character selecting mechanism from hammer bracket 21 supporting typewheel 31 every time hammer bracket 21 carries out the printing action so that the printing action of hammer bracket 21 can be continuously carried out after completion of the typecharacter selecting operation without any interruption and this fact results in the high-speed typewriting operation capability of the typewriting mechanism of the present invention.

Now referring to FIG. 6, a mechanism for locking typewheel 31 after completion of the circumferential and the vertical type-character selection, is schematically and perspectively shown.

As is seen from FIG. 3, thislocking mechanism is arranged at the lower portion of swingable hammer bracket 21 of the type carrier 11.

In FIG. 6, immediately before completion of the type-character selecting operation, hammer magnet 23 is energized to rotate output shaft 23a in the clockwise direction against the force of a spring 103 and as a result locking lever 37 starts to rotate in the counterclockwise direction about shaft 370 and against the force of a spring 105 via lever arm 35 and engages with a notch 85a of a trigger lever 85 at its one end 37b. And at this moment, the other end 370 of locking lever 37 is disconnected from an engagement with a vertical locking lever 87 and a rotational locking lever 89 so that bothlocking levers 87' and 89 are rotated about a vertical shaft 91 in the clockwise direction due to the forces of respective springs 93- and 95.

As a result of this, locking levers 87 and 85 simultaneously engage with one of the locking grooves 97 formed at the rear edge of rack member 67 and one of the locking teeth 101 of a locking wheel 99 fixed at the lower end of shaft 65 of typewheel 31 respectively as shown in FIG. 6, and typewheel 31 is then put into a locked state so that a certain selected type thereon can be correctly printed by the swinging movement thereof.

It should be understood from FIG. 6 that at the moment when the typewriting operation is completed and hammer magnet 23 is-deenergized, the forces of the

springs

103 and 105 cause locking lever 37 to rotate in the clockwise direction so that the end 370 of locking lever 37 returns to re-engage with both vertical and ro- -tational locking levers 87 and 89 while causing a coun- 31 while referring to FIG..7, energized hammer magnet 23 continues to pull locking lever 37 via lever arm 35

againstsprings

103 and 105 until the end 37b of locking lever 37 contacts the upper edge of notch 85a of trigger lever 85 and the counterclockwise rotation of locking lever 37 is restricted momentarily by trigger lever 85.

However, further pulling force of hammer magnet 23 applied to locking lever 37 via lever arm 35 causes hammer bracket 21 to start its swinging action about pivots 33 fixed to

carrier frames

29a, 29b (not shown in FIG. 7) from an initial position away from platen 13 (not shown in FIG. 7).

As soon as the swinging action of hammer bracket 21 starts, hammer magnet 23 is deenergized, and there fore, the torque thereof applied to output shaft 23a is reduced. However, at this moment due to the inertia of swinging hammer bracket 21, the printing operation of hammer bracket 21 is positively achieved, that is to say, typewheel 31 strikes against the typewriter paper 15 around platen 13 through the ink ribbon similar to the conventional manner so that the selected type-chamber is printed on the. paper 15.

When typewheel 31 strikes against platen 13 through paper 15, sudden stoppage of the swinging action of hammer bracket 21 produces inertial rotation of output shaft 23a which maintains locking lever 37 in the pulled state by lever arm 35 and as a result, locking of typewheel 31 is kept during the printing action of hammer bracket 21.

When the inertial rotation of output shaft 23a of hammer magnet 23 is exhausted, the forces of springs 103 and act to release the locking of typewheel 31 as previously explained and simultaneously, act to bring back hammer bracket 21 to the initial position where hammer bracket 21 contacts a stopper 107 fixedly attached to the inner side of carrier frame 29a as shown in FIG. 4.

Thus, the printing operation of hammer bracket 21 is completed.

Here it should be noted in FIGS. 3 and 8 that a toggle spring 109 bridged between carrier frame 29a and hammer bracket 21 has its neutral point at the preselected position which is five-sixths the distance from the initial position of hammer bracket 21 to platen 13.

Therefore, when hammer bracket 21 is swung exceeding the neutral position, toggle spring 109 forces hammer bracket 21 to further swing toward platen 13, and until hammer bracket 21 reaches the neutral position, toggle spring 109 applies the spring force to hammer bracket 21 so as to restrict the swinging action of hammer bracket 21. That is to say, toggle spring 109 always resists the occurrence of both swinging and returning actions of hammer bracket 21, so that both locking and release of locking of typewheel 31 are accomplished before the occurrence of movement of hammer bracket 21.

Now, a brief description of the rotary type hammer magnet 23 will be given with reference to FIG. 9 and FIG. 10.

FIG. 9 illustrates the positional relationship between the stator and the rotor of the rotary magnet 23.

In the structure of hammer magnet 23, a rotor fixedly mounted on output shaft 23a (FIG. 6) and having equi-angularly spaced poles 117 rotates with respect to a stationary stator 119 which has poles arranged at the same pitch as poles 117 of rotor 115.

In the non-operating state, poles 117 of rotor 115 are positioned so as to be staggered from poles 121 of stator 119 by an angle 6, as shown in FIG. 9(a,).

In this state, when stator 1 19 is energized, the attractive force acting between stator 119 and rotor 115 produces maximum torque which makes rotor 115 rotate with output shaft 23a, and when rotor 115 rotates until poles 117 are aligned with poles 121 of stator 119 (position 0,, of FIG. 9(a refers to), the torque of output shafts 23a or rotor 115 is extinguished.

FIG. 10 indicates the torque characteristics curve of rotary hammer magnet 23 with respect to the difference of angle of stagger between rotor 115 and stator 119.

In the case where this hammer magnet 23 is employed for driving the typewriter mechanism of the present invention, the arrangement is such that at an angular position 1 of FIG. 10, the printing action of typewheel 31 starts, and at an angular position 0,, of FIG. 10, the printing of a type is completed.

In FIG. 10, a dotted line indicates a torque characteristics curve of spring 103 which resists the rotation of rotor 115 and output shaft 23a.

According to the foregoing, it will be understood that at the initial state of printing action of typewheel 31, hammer magnet 23 applies a large torque to typewheel 31 so as to effectively accelerate the swinging action of typewheel 31, but according to the progress of the swinging action of typewheel 31, the torque of hammer magnet 23 becomes small while the torque of the resisting spring 103 becomes large and as a result, the printing action of typewheel 31 is carried out merely by its inertial swinging action so that printing of a type is performed by a momentary contact only of typewheel 31 with platen 13. Therefore, clear and uniform printing of a type can be achieved because no vibrating action of typewheel 31 occurs due to the small contact pressure between typewheel 31 and platen 13. That is to say, double printing action of typewheel 31 can be completely avoided.

Also, it will be understood that by controlling the exciting current given to hammer magnet 23, control of the printing torque. applied to typewheel 31 is easily carried out. I I

Therefore, corresponding to the number of typewriter papers which must be printed at the same time, the above contact pressure between typewheel 31 and platen 13 can be suitably and easily controlled.

Further, it will be understood that according to the employment of rotary hammer magnet 23, impact occurs only when typewheel 31 strikes against platen l3 and also, when hammer bracket 21 returns to stopper 107 (FIG. 4) and as a result, noise of the typewriting mechanism is extremely reduced compared with the conventional mechanism wherein heavy hammering action is used for producing printing pressure.

Further, it will be understood from FIG. that as the torque of hammer magnet 23 is almost zero, return of typewheel 31 due to the torque of spring 103 starts immediately after completion of printing of a type so that the whole typewriting operation can be carried out at high-speed.

Now, further detailed description with respect to the rotary type hammer magnet will be hereinafter mentioned referring to an example thereof shown in FIG. 11 toFIG. 14. t

InFIG. l1,shaft 23a ismade of magnetic material, and rotors 115a, 115b having a plurality of

poles

117a, 117b, are fixedly mounted on shaft 23a. Numeral 123 is a bobbin made of non-magnetic material and is arranged on shaft 23a and between rotors 115a, 115b while keeping suitable gaps between bobbin 123 and these other elements. .Numeral 127 is an excitation winding installed on the bobbin 123. Numerals 119a, 11% are stators inserted over rotors 115a, 115b, and excitation windings 127 while keeping slight radial air gaps therebetween. These stators 119a, 11% are provided with poles 121a, 12lb arranged at the same equiangular spaces as rotor-

poles

117a, 117b. Numerals 129a, 12% are bearings supporting the opposite ends of shaft23a so that shaft 23a can be rotated. Numerals 131a, 131b are bracket members for stationarily supporting the above-mentioned stators 119a, 11% as well as holding bearings 129a, 12% as shown in FIG. 11.

Numeral 125 is a pawl provided for the abovementioned bobbin 123 for restricting the rotation of bobbin 123.

In the above arrangement of the hammer magnet 23, when excitation current is applied to excitation windings 127, magnetic flux through shaft 23a, rotors 115a,

b and stators 119a, 11% is formed and as a result, magnetic attractive forces are produced between

poles

117a and 121a, and between poles 1l7b and 121b, re spectively.

These attractive forces produce a torque on rotors 115a, 115b and shaft 23a when poles of rotors 115a, 115b and poles of stators 119a, 11% are in a staggered relationship and as a result, shaft 23 rotates until the rotors and stators are aligned.

When the excitation is stopped, shaft 23a with rotors 115a, 115b is capable of returning to the initial state by a suitable means such as a spring.

Now, assuming that in the non-operating initial state, poles of rotors 115a, 115b are positioned between poles of stators 119a, 11% as shown in FIG. 12c, and in the operating state, poles of rotors 115a, 115b are magnetically attracted to poles of stators 119a, 1 19b as shown in FIG. 12a, the torque characteristics curve shown in FIG. 12d is obtained corresponding to angle of stagger between poles of rotors 115a, 115b and stators 119a, 11% in both angular directions as shown by angles 0 and -0 in FIG. 12a.

In FIG. 12d, 6 and 6, indicate positions where the maximum torque is obtained from rotors 115a, 115b.

' FIG. 120 indicates the positional relationship between rotors 115a, 115b and stators 119a, 11% when this maximum torque is obtained.

As is seen from FIG. 120, the maximum torque can be obtained when

poles

117a, 117b of rotors 115a, 115b depart from poles 121a, l21b of stators 119a, 11%.

The positions 6 and 6 of FIG. 12d indicate the second zero torque positions where poles 1170, 117b of rotors 115a, 115b are positioned in the middle of

poles

121a, 121b of stators 119a, 11% as is seen from FIG. 12c.

In the torque characteristics shown in FIG. 12d, if the region 6, only from the position 6 is used, the initial torque becomes maximum while the end torque becomes minimum.

Therefore, the initial maximum torque serves as an acceleration torque for shaft 23a and the end minimum torque serves to restrict the impacting action of shaft 23a.

Referring to FIG. 13a, b, another positional relationship between the rotors and stators of hammer magnet 23 and its torque characteristics curve are indicated.

In FIG. 13a, an example wherein stators 119a and 11% are staggered from each other by an angle 0,, is shown and in this case, the maximum torque obtained from shaft 23a may be reduced in value. However, an averaged torque characteristics curve can be obtained as shown in FIG. 13b. And it will be understood that if 0,, is suitably changed, any kind of torque characteristics curve can be obtained.

FIG. 14a, b indicates another case in which output shaft 23a of hammer magnet 23 has a large end torque, because the rotation of output shaft 23a is stopped by a suitable magnetic stop member provided over a portion of the respective poles of rotor 115a or 11512. That is to say, when the motion of shaft 23a is stopped by the stop member, magnetic attractive forces between rotors 115a, 115b and stators 119a, 1191; produce the largest or maximum torque as shown in FIG. 14b.

In this case, the magnitude of the end torque can be suitably set by changing the number of stop members which may be provided for all poles 117a, 1l7b of rotors 1 15a, 1 15b or for merely selected numbers of poles 117a; ll7b of rotors 115a, 115b.

Of course, the stop members may be provided for

poles

121a, 121b of the stators instead whereby the same effect as the foregoing can be expected.

- Further, in the above arrangement of the rotary type magnet, sliding surfaces exist only in bearings 129a, 12% and as a result, the abrasion effect which exists in the conventional plunger type magnet, can be greatly reduced or eliminated.

Also, almost all elements such as rotors 115a, 115b, stators 119a, 119b, and a shaft 23a, are made of magnetic material, so that the leakage of magnetic flux produced by energizing of excitation windings 127 is very small and as a result, a magnetic driving source of superior efficiency can be obtained.

Now, the typewriting mechanism of the present invention will be again considered.

FIGS. 15 and 16 illustrate a mechanism for. feeding In the above mechanism, the ribbon feed operation is carried out when hammer bracket 21 swings back to the initial position.

When hammer bracket 21 swings toward platen 13 to carry out a printing operation, feed pawl 153 of the ribbon feed mechanism 27 returns to its initial position.

FIG. 17 is a diagram schematically illustrating the operational sequence of the typewriting mechanism of the present invention, and the abscissa indicates time (T), and the ordinate indicates progress of the respective operations.

In the diagram of FIG. 1, period T, represents one complete cycle of the typewriting operation from the type-character selection to the release of locking of the typewheel. In the period T firstly, the type-character selecting operation is carried out and then, immediately before completion of the type-characterselecan ink ribbon for-the next: typewriting operation after completion of printing of a certain type.

This mechanism is actuated by the swinging action of hammer bracket 21.

In FIGS. 15 and 16, when hammer bracket 21 carries out swinging action as described before, a feed arm 141 engaged with a pin 143 fixed to hammer bracket 21 is actuated to carry out a swinging action about an axis 145, and this swinging action of feed arm 141 is transmitted to the ribbon feed mechanism 27 via a feed link Feed link 141 is connected to the middle portion of a feed lever 149 which is rotatable about a vertical axis 151 disposed at one end of feed lever 149, and therefore, movement of feed link 147 in the direction shown by an arrow .Pcauses the swinging motion of feed ratchet wheel 155a through engagement of a stop pawl 157a and ratchet of ratchet wheel 155a as can be seen from FIG. 15.

A spring 159 provides a spring force to effectuate positive engagement of feed pawl 153 and ratchet wheel 155a and also, of back stop lever 157 and ratchet wheel 155a.

The rotation of ratchet wheel 155a provides the ribbon feeding operation through spool 161a because a ribbon cartridge (not shown) which contains an ink ribbon, is mounted on both spools 161a, 161b.

That is, when one of the spools 161a, 161b rotates, the winding action of an ink ribbon is carried outwithin the cartridge.

When the ribbon feed operation caused by ratchet wheel 155a is completed, feed pawl 153 engages with ratchet-wheel l55b through a reversing mechanism (not-shown) and the ribbon feed operation caused by 6 ratchet wheel 155b is carried out in the reverse direction of the foregoing.

tion, the locking operation of the typewheel starts and when the locking operation is completed, the printing operation starts and the printing of a type is completed at time T After completion of the printing operation, the ribbon feeding operation and the releasing operation of locking of the typewheel are carried out.

It will be understood from the foregoing and the diagram of FIG. 17 that as the locking of the typewheel is released immediately after completion of the printing operation, the next typewriting operation can start immediately and as a result, high-speed typewriting can be achieved according to the present invention.

Now it is to be understood that numerous variants and modifications of the typewriting mechanism of the typewriter machine can be effectuated within the scope and the spirit of the present invention.

What is claimed is:

l. A typewriting mechanism for a typewriter machine comprising bracket means capable of swinging about an axis toward the platen of the typewriter machine, a typewheel having a number of types on the surface thereof and rotatably and vertically movably supported by said bracket means,

said typewheel being capable of selecting one of said types through a type-character selecting mechanism having a gear meshing engagement, rotary magnet means combined with said bracket means and actuating the swinging motion of said bracket means upon being electrically energized so that said typewheel strikes against said platen while carrying out printing of a type of said typewheel,

rotary magnet means comprising a rotatable shaft,

rotor poles which are fixedly mounted on and equiangularly arranged around said rotatable shaft, stator poles equiangularly arranged around said rotor poles, and excitation windings provided for excitation of said stator poles and said rotor poles, and rotor poles, and

spring means for maintaining an initial position of said bracket means, said initial position of said bracket means being defined by a fixedly arranged stopper with which said bracket means comes into contact by the force of said spring means,

said rotary magnet means being associated with said bracket means in a manner so that when said bracket means stays in the initial position said rotor poles are positioned so as to be angularly staggered from said stator poles.

2. A typewriting mechanism for a typewriter machine as claimed in claim 1, wherein the center of swing of said bracket means and the points of contact of the pitch circles of respective meshed gears of said typecharacter selecting mechanism lie on the same line.

3. A typewriting mechanism for a typewriter machine as claimed in claim 1, further comprising link means driven by said rotary magnet means combined with said bracket means, said link means locking the rotational and vertical motion of said typewheel with respect to said bracket means whereby said selected type is positioned to be printed.

4. A typewriting mechanism for a typewriter machine as claimedin claim 1, further comprising lever means actuated by said bracket means through said swinging motion of said bracket means, said lever means including a feed pawl for driving an ink ribbon feed mechanism, said feed pawl engaging said feed mechanism to feed said ink ribbon when said bracket means swings back to an initial position and said feed pawl returning to its initial position when said bracket means swings so that saidtype wheel strikes against said platen.

5. A typewriting mechanism for a typewriter machine as claimed in claim 1, wherein said bracket means and said rotary magnet means are combined into carriage means which carries out carriage spacing motion along said platen during the typewriting operation.

6. A typewriting mechanism for a typewriter machine comprising:

bracket means capable of swinging about an axis toward the platen of the typewriter machine;

a typewheel having a number of types on the surface thereof and rotatably and vertically movably supported by a vertical shaft mounted on said bracket means;

type-character selecting means including gear meshing engagement for carrying out selection of one of said types of which is to be printed;

a rotary magnet having an output shaft rotated upon electrical energization of the rotary magnet;

means for actuating a swinging motion of said bracket means upon rotation of the output shaft of said'rotary magnet so that said typewheel strikes against said platen while carrying out printing of a type of said typewheel, said actuating means comprising a first lever arm radially extending from said output shaft of said rotary magnet, a second lever arm having one end connected to the outermost end of said first lever arm and the other end associated with bracket means, and spring means for exerting restoring force on said second lever arm,

said rotary magnet and said bracket means being incorporated into a carriage means carrying out spacing motion along said platen during the typewriting operation; v

said rotary magnet comprising rotor poles which are fixedly mounted on and equiangularly arranged around said output shaft, stator poles equiangularly arranged around said rotor poles, and excitation windings provided for excitation of said stator poles and said rotor poles; and

said spring means for maintaining an initial position of the bracket means, said initial position of said bracket means being defined by a fixedly arranged stopper with which the bracket means comes into contact by the force of the spring means;

said rotary magnet being associated with said bracket means in a manner so that when the bracket means stays in the initial position said rotor poles are positioned so as to be angularly staggered from said stator poles.

7. A typewriting mechanism for a typewriter machine as claimed in claim 6, wherein said type-character selecting means comprises:

a first rectangular traverse shaft rotated to transmit a circumferential type-character selecting motion to said typewheel;

a second rectangular transverse shaft rotated to transmit a vertical type-character selecting motion to said typewheel;

a first gear fixedly mounted on said first transverse shaft transversely sliding in accordance with said spacing movement of said bracket means;

a second gear fixedly mounted on said second transverse shaft transversely sliding in accordance with the spacing movement of said bracket means;

an idler gear freely rotatable on said first rectangular transverse shaft and being in meshing engagement with said second gear;

a third gear fixedly mounted on said vertical shaft and engaging with said first gear to cause said circumferential type-character selecting motion of said typewheel via said vertical shaft upon rotation of said first shaft;

a rack member having gear teeth formed at one vertical edge thereof and vertically slidably mounted on said bracket means while being rotatably associated with said typewheel, said rack gear teeth being in meshing engagement with said idler gear to cause said vertical type-character selecting motion of said typewheel upon rotation of said second shaft, and;

the points of contact of the pitch circles of said first and third gears and of said idler and rack gears lie on the center line of swinging motion of said bracket means.

8. A typewriting mechanism for a typewriter machine as claimed in claim 6, further comprising locking means for releasably locking said typewheel upon printing of said type to be printed comprising:

a member having vertically arranged teeth defining locking grooves between said adjacent teeth and vertically slidably mounted on said bracket means while being rotatably associated with said typewheel;

a locking gear fixed on said vertical shaft;

a first horizontal locking lever angularly movable on said bracket means and being engageable with one of said locking grooves of said member in an operated position thereof;

a second horizontal lever angularly movable on said bracket means and being engageable with said locking gear in an operated position thereof;

spring means for urging said first and second horizontal locking levers to initial positions thereof, and;

a third locking lever associated with said second lever arm to urge said first and second locking levers to the operated position from the initial positions in accordance with said electrical energization of said rotary magnet.

Claims

1. A typewriting mechanism for a typewriter machine comprising bracket means capable of swinging about an axis toward the platen of the typewriter machine, a typewheel having a number of types on the surface thereof and rotatably and vertically movably supported by said bracket means, said typewheel being capable of selecting one of said types through a type-character selecting mechanism having a gear meshing engagement, rotary magnet means combined with said bracket means and actuating the swinging motion of said bracket means upon being electrically energized so that said typewheel strikes against said platen while carrying out printing of a type of said typewheel, rotary magnet means comprising a rotatable shaft, rotor poles which are fixedly mounted on and equiangularly arranged around said rotatable shaft, stator poles equiangularly arranged around said rotor poles, and excitation windings provided for excitation of said stator poles and said rotor poles, and rotor poles, and spring means for maintaining an initial position of said bracket means, said initial position of said bracket means being defined by a fixedly arranged stopper with which said bracket means comes into contact by the force of said spring means, said rotary magnet means being associated with said bracket means in a manner so that when said bracket means stays in the initial position said rotor poles are positioned so as to be angularly staggered from said stator poles.

2. A typewriting mechanism for a typewriter machine as claimed in claim 1, wherein the center of swing of said bracket means and the points of contact of the pitch circles of respective meshed gears of said type-character selecting mechanism lie on the same line.

4. A typewriting mechanism for a typewriter machine as claimed in claim 1, further comprising lever means actuated by said bracket means through said swinging motion of said bracket means, said lever means including a feed pawl for driving an ink ribbon feed mechanism, said feed pawl engaging said feed mechanism to feed said ink ribbon when said bracket means swings back to an initial position and said feed pawl returning to its initial position when said bracket means swings so that said type wheel strikes against said platen.

6. A typewriting mechanism for a typewriter machine comprising: bracket means capable of swinging about an axis toward the platen of the typewriter machine; a typewheel having a number of types on the surface thereof and rotatably and vertically movably supported by a vertical shaft mounted on said bracket means; type-character selecting means including gear meshing engagement for carrying out selection of one of said types of which is to be printed; a rotary magnet having an output shaft rotated upon electrical energization of the rotary magnet; means for actuating a swinging motion of said bracket means upon rotation of the output shaft of said rotary magnet so that said typewheel strikes against said platen while carrying out printing of a type of said typewheel, said actuating means comprising a first lever arm radially extending from said output shaft of said rotary magnet, a second lever arm having one end connected to the outermost end of said first lever arm and the other end associated with bracket means, and spring means for exerting restoring force on said second lever arm, said rotary magnet and said bracket means being incorporated into a carriage means carrying out spacing motion along said platen during the typewriting operation; said rotary magnet comprising rotor poles which are fixedly mounted on and equiangularly arranged around said output shaft, stator poles equiangularly arranged around said rotor poles, and excitation windings provided for excitation of said stator poles and said rotor poles; and said spring means for maintaining an initial position of the bracket means, said initial position of said bracket means being defined by a fixedly arranged stopper with which the bracket means comes into contact by the force of the spring means; said rotary magnet being associated with said bracket means in a manner so that when the bracket means stays in the initial position said rotor poles are positioned so as to be angularly staggered from said stator poles.

7. A typewriting mechanism for a typewriter machine as claimed in claim 6, wherein said type-character selecting means comprises: a first rectangular traverse shaft rotated to transmit a circumferential type-character selecting motion to said typewheel; a second rectangular transverse shaft rotated to transmit a vertical type-character selecting motion to said typewheel; a first gear fixedly mounted on said first transverse shaft transversely sliding in accordance with said spacing movement of said bracket means; a second gear fixedly mounted on said second transverse shaft transversely sliding in accordance with the spacing movement of said bracket means; an idler gear freely rotatable on said first rectangular transverse shaft and being in meshing engagement with said second gear; a third gear fixedly mounted on said vertical shaft and engaging with said first gear to cause said circumferential type-character selecting motion of said typewheel via said vertical shaft upon rotation of said first shaft; a rack member having gear teeth formed at one vertical edge thereof and vertically slidably mounted on said bracKet means while being rotatably associated with said typewheel, said rack gear teeth being in meshing engagement with said idler gear to cause said vertical type-character selecting motion of said typewheel upon rotation of said second shaft, and; the points of contact of the pitch circles of said first and third gears and of said idler and rack gears lie on the center line of swinging motion of said bracket means.

8. A typewriting mechanism for a typewriter machine as claimed in claim 6, further comprising locking means for releasably locking said typewheel upon printing of said type to be printed comprising: a member having vertically arranged teeth defining locking grooves between said adjacent teeth and vertically slidably mounted on said bracket means while being rotatably associated with said typewheel; a locking gear fixed on said vertical shaft; a first horizontal locking lever angularly movable on said bracket means and being engageable with one of said locking grooves of said member in an operated position thereof; a second horizontal lever angularly movable on said bracket means and being engageable with said locking gear in an operated position thereof; spring means for urging said first and second horizontal locking levers to initial positions thereof, and; a third locking lever associated with said second lever arm to urge said first and second locking levers to the operated position from the initial positions in accordance with said electrical energization of said rotary magnet.