US3832942A

US3832942A - Flying parallel printer for table electronic calculators

Info

Publication number: US3832942A
Application number: US00350364A
Authority: US
Inventors: S Murayoshi
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1972-04-19
Filing date: 1973-04-12
Publication date: 1974-09-03
Anticipated expiration: 1991-09-03
Also published as: PL92136B1; GB1366840A; DE2319256A1; DE2319256B2; JPS5254412Y2; JPS495324U

Abstract

A printer comprising a plurality of type hammers each provided with a trigger lever mounted for pivotal motion thereon for a limited range of movement relative to the respective type hammer. Each type hammer has a controller associated therewith, and each controller is actuated by an electromagnet associated therewith. When any one electromagnet is energized, the controller associated therewith moves the trigger lever into the path of movement of a projecting edge of a flip shaft so that the latter may flip the trigger lever to thereby cause the trigger lever and the type hammer to move in swinging motion to effect printing of a symbol on the printing sheet.

Description

United States Patent [191 Murayoshi Sept. 3, 1974 [54] FLYING PARALLEL PRINTER FOR TABLE 3,623,429 11/1971 lmahashi et a1 101/93 C ELECTRONIC CALCULATORS 3,673,956 7/1972 Hukor et a1. 101/93 C [75] Inventor: Seiii Murayoshi, Tokyo, Japan [73] Assignee: Ricoh Co., Ltd., Tokyo, Japan [22] Filed: Apr. 12, 1973 [21] Appl. No.: 350,364

[30] Foreign Application Priority Data Apr. 19, 1972 Japan 47-46883 52 US. Cl 101/93 c [51] Int. Cl B4lj 9/08 [58] Field of Search 101/93 C; 235/61 P [56] References Cited UNITED STATES PATENTS 3,255,693 6/1966 Eissfeldt et al 101/93 C 3,289,575 12/1966 Wassermann 1 101/93 C 3,292,531 12/1966 Mutz 101/93 C 3,517,611 6/1970 Fink 1 lOl/93 C 3,587,456 6/1971 Jaensch 101/93 C Primary Examiner-Robert E. Pulfrey Assistant ExaminerEdward M. Coven Attorney, Agent, or Firm-Cooper, Dunham, Clark, Griffin & Moran [57] ABSTRACT A printer comprising a plurality of type hammers each provided with a trigger lever mounted for pivotal mo- 11 Claims, 15 Drawing Figures PATENTEnsEP 31914 WEE-I 1 0f 6 SHEET 20$ 6 PATENTEDSEP 3mm FIG F-IG.4

PATENTED SEP 3 74 SHEET 3 OF 6 PATENTED 31974 3.832.942

SNEEI 50$ 6 PATENTEU SEP 74 SHEET B 0! 6 FIG.||

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FIGQRZ FLYING PARALLEL PRINTER FOR TABLE ELECTRONIC CALCULATORS BACKGROUND OF THE INVENTION This invention relates to flying parallel printers for table electronic calculators, and more particularly it is concerned with a flying printer comprising a plurality of type hammers arranged in side-by-side relationship on a single shaft. 7

Table electronic calculators of the type having a printer attached thereto generally operate such that when keys arranged on the upper surface of the instrument are depressed manually, logic circuits are actuated and the result of calculation can be recorded on a printing sheet by a printing mechanism.

Proposals have hitherto been made to use various types of printing mechanisms or printers for printing the result of calculations on a printing sheet. Printers of the prior art generally have had a disadvantage in that they are complex in construction and difficulty is experienced in actuating the type hammers in good timing relative to the type cylinder rotating at high speed. Misoperation of the type hammers results in double printing or no printing of a symbol.

When the type cylinder rotates at low speed or when the flip shaft rotates at low speed, there is no trouble. However, when the number of revolutions of the flip shaft reaches 3,000 or more, misoperation of the type hammers tends to occur.

SUMMARY OF THE INVENTION This operation has as its object the provision, in a table electronic calculator of the type having a rotating type cylinder, of a flying parallel printer compact in size and simple in construction which is free from the disadvantage of printing the same symbol twice or printing no symbol at all.

The characterizing feature of the invention is that each of the type hammers has a trigger lever pivotally connected to the type hammer and adapted to be flipped at a suitable time by a projection edge formed in a shaft rotating at high speed, each trigger lever being caused by an associated controller to move in swinging motion relative to the respective type hammer, so that the trigger lever can be moved into and out the path of movement of the projecting edge of the shaft, whereby a printing operation can be performed by the type hammer. The provision of each type hammer with a trigger lever simplifies the construction of a printer and permits the printer to operate positively as compared with conventional printers attached to table electronic calculators.

BRIEF EXPLANATION OF THE DRAWINGS FIG. 5 is an exploded perspective view of a type ham mer in relation to an associated controller and a flip shaft;

FIG. 6 is an enlarged side view of the type hammer assembly in explanation of a hammering operation of each type hammer;

FIG. 7 is an exploded perspective view of a ribbon feed mechanism forming a part of the printer of FIG.

FIG. 8 is a plan view of the ribbon feed mechanism;

FIG. 9 to FIG. 14 are views in explanation of operation of the ribbon feed mechanism; and

FIG. 15 is a view showing the operation of a ribbon changing mechanism forming a part of the printer of FIG. 1.

DETAILED DESCRIPTION FIG. 1 is a plan view of a flying parallel printer incorporating the present invention. Arranged between vertically oriented right and left base plates 1 and 2 are a type cylinder 3, a printing sheet feed roller 4, a plurality of type hammers 5 arranged in side-by-side relationship and juxtaposed to the peripheral surface of the type cylinder 3, a flip shaft 6 (FIG. 5 adapted to actuate the type hammers 5, a ribbon 9 wound on two

reels

7 and 8 and having a portion disposed between the peripheral surface of the type cylinder 3 and the plurality of type hammers 5, and a ribbon feed mechanism.

The aforementioned parts and mechanism are suitably driven by a motor M rotating at high speed and having an output shaft Ma extending through the left base plate 1 outwardly thereof and mounting a transmission wheel 10 at its outward end. The flip shaft 6 (FIG. 5) and a center shaft 3a (FIG. I) for the type cylinder 3 extend through the two base plates I and 2 outwardly thereof. An outer end portion 6a of flip shaft 6 (FIG. 2) extending out of the left side plate 1 has a power transmission wheel 11 secured thereto. An endless timing belt 12 is trained over the transmission wheels 10 and 11 to transmit the drive force of motor M to the flip shaft 6. The two transmission wheels also function as flywheels, so that a great amount of inertial and rotational moment energy can be stored in the flip shaft 6.

Rotation of the flip-shaft 6 is transmitted to the type cylinder 3 and to the ribbon feed mechanism. More specifically, as shown in FIG. 3, an outer end portion 6b of flip shaft 6 extending out of the right side plate 2 has a gear 13 securedthereto and in meshing engagement with a larger diameter gear 14 which has a coaxial and integral smaller diameter gear 15 maintained in meshing engagement with a gear 16 secured to the center shaft 3a for the type cylinder 3 extending out of the right base plate 2. The number of revolutions of the type cylinder 3 is set such that the type cylinder 3 rotates through an angle corresponding to the distance between two adjacent rows of symbols of figures thereon for each complete revolution of the flip shaft 6. In the embodiment shown and described herein, there are 15 rows of figures or symbols on the periphery of the type cylinder 3, so that a speed ratio of 1/ l5 can be obtained through the gear train 13 and 16.

Rotation of the flip shaft 6 and rotation of the type cylinder 3 are sensed by detector means. As shown in FIG. 2, rotation of flip shaft 6 is sensed-by a detection means consisting of a ring 17 secured to transmission wheel 11 and formed with two projections 17a and 17b and an electric pulse generator 18 sensing the movement of projections 17a and 17b. More specifically, the electric pulse generator 18 consists of a cylindrical permanent magnet 19 and a sensing coil 21 wound on a center shaft 20 extending upwardly from the pennanent magnet 19. When projections 17a and 17b move over the upper end surface of center shaft 20, pulse voltage is produced in the sensing coil 21 as a result of changes in the magnetic flux and taken out as electric pulses.

The two projections 17a and 17b extending outwardly from the ring 17 form therebetween an angle of about 60 with respect to the center of ring 17. When the ring 17 rotates in the direction of an arrow a, the sensing coil 21 senses the movement of projection 17b and generates an electric pulse which renders a controller actuating electromagnet (subsequently to be described) ready for energization. The electromagnet is then energized by a signal from a logic circuit. The energization takes place while the sensing coil 21 senses the movement of projection 17a. Accordingly, from the time one projection 17b is sensed till the other projection 17a is sensed, or while the ring 17 rotates through an angle of about 300, the controller actuating electromagnet remains energized, so that a type hammer 5 associated with the electromagnet is actuated by the flip shaft 6 to effect printing of a figure.

In actual'practice, however, there is a slight gap between electric timing and mechanical timing so as to reduce as much as possible the impact which might otherwise be applied fully to the parts. Thus, the flip shaft 6 flips a trigger hammer disposed at the other end of the type hammer after the electromagnet is deenergized to cause the type hammer to operate as subsequently to be described.

In the embodiment shown and described herein, two projections 17a and 17b are used for causing a type hammer to operate. It is to be understood that only one projection may be used in place of the two projections.

Referring to FIG. 2, the end portion of the center shaft 30 extending out of the left base plate 1 has a short cylinder 22 secured thereto. The short cylinder 22 rotates in the direction of an arrow 11 and has a chip 23 fitted in its periphery and disposed radially of the cylinder 22. A magnetic head 24 is arranged near the short cylinder 22. When the short cylinder 22 rotates and the chip 23 passes by the head 24, a magnetic change is caused in the magnetic head 24 which produces an induced pulse voltage which is taken out as an electric pulse signal. Generation of this signal indicates that the type cylinder 3 has made one complete revolution.

The calculator of this embodiment adopts a random start system of the print initiation type, so that it is possible to type out quickly a signal produced by an electric calculation circuit when printing is effected. More specifically, the printer is set through a home signal such that an electric signal or a so-called timing signal which is generated when projection 17a moves on the shaft of sensing coil 21 makes figures on the type cylinder 3 to be associated with specific positions. Thus, upon receipt of a printing initiation signal, printing can be started with any figure on the periphery of the type cylinder 3. That is, the type cylinder 3 rotates through an angle corresponding to the distance between the adjacent two rows of figures on the type cylinder 3 when projection 17a makes one complete revolution relative to shaft 20, and the timing signal is used as a signal indicating the initiation or termination of printing.

Printing sheet feed, ribbon feed and ribbon color switching are also controlled by a timing signal.

The function of a home signal which is generated when the chip 23 moves by the head 24 is to select the quantity of current supplied to an electromagnet MG (FIG. 4) or the time interval during which the electromagnet is energized to attract the other arm 30b of a controller 30 from two angles of rotation 01 and 03 formed by two projections 17a and 1712 as shown in FIG. 2.

In this embodiment, the angle 62 is selected and its value is 300. It is understood that the value may be 200 or depending on the capacity of the electromagnet MG. A timing signal and a home signal function to associate each numeral on the type cylinder to a specific position. For example, a timing signal which is generated when projection 17a moves on shaft 20 and a home signal which is generated when the chip 23 passes by the head 24 overlap, and the hammers are indexed with the row of figures zero when the machine is inoperative.

As shown in FIG. 1, l5 figures and two other symbols are formed in relief and arranged axially of the type cylinder 3 in each of the 13 rows of symbols arranged peripherally around the type cylinder 3.

As shown in FIG. 1, the type cylinder 3 is formed in relief on its periphery with numerals and other symbols arranged in 13 rows disposed axially of the cylinder and in 17 columns disposed peripherally of the cylinder. The 13 axial rows are each for one of FIGS. 0 to 9 and three symbols. Of the 17 peripheral columns, fifteen columns are for figures from 0 to 9 and three symbols, and two columns are for symbols. Indexed with one of l3 peripheral rows of symbols is an assembly of l7 type hammers 5, for example, one type hammer 5 for each symbol in the row. The type hammers 5 are parallel to the type cylinder 3 and flip shaft 6 as shown in FIG. 4 and pivotally supported for swinging motion on a shaft 25 mounted between the two base plates 1 and 2.

Referring to FIGS. 46, each type hammer 5 includes an upwardly extending arm 5a disposed near the periphery of the type cylinder 3 and formed with a hammer 5b at one upper side thereof. Each type hammer 5 also includes a downwardly extending arm 50 having a trigger lever 26 pivoted thereon at 26a. Each trigger lever 26 has a leg 26a and a projection 26b adapted to be brought into engagement with the periphery of the flip shaft 6 when the trigger lever 26 is brought to its operative position.

The trigger lever 26 is adapted to swing clockwise about its pivot 26a in FIG. 4 and FIG. 6 into its operative position. The movement of trigger lever 26 relative to the type hammer 5 restricted by stopper means provided on the type hammer and trigger lever. More specifically, the stopper means comprises a pin 27 connected to a tail 260 of the trigger lever 26 and an opening 5d fonned in another arm 50 of the type hammer 5 for receiving the pin 27 therein. The opening 5d has a diameter such that when the trigger lever 26 swings clockwise about the pivot 26a, the pin 27 is brought into engagement with the edge of opening 5d as the projection 26b is brought into contact with the periphery of the flip shaft 6, so that the trigger lever 26 stops swinging. The type hammer 5 is normally urged to swing counter clockwise about shaft 25 by the biasing force of a spring 29 mounted between arm 5a and a guide 28 for the arm 50, the swinging of the type harnmer 5 being precluded by a stop shaft 38 positioned against arm 5c. The tail 260 of trigger lever 26 mounted on the arm 50 of type hammer 5 is pushed upwardly by one arm 30a of an actuator 30 pivotally connected to a support shaft 31 parallel to shaft 25. The number of actuators 30 corresponds to that of type hammers 5.

There are two types of actuators 30 arranged alternately on shaft 31. One type has the other arm 30b extending straightforwardly from one arm 30a while the other type has the other 30b extending downwardly from free end of one arm 30a at right angles thereto, the other arm 30b being attracted by the corresponding electromagnet MB irrespective of the types. The reason why there are two types of actuators 30 is that it is desired to reduce the space occupied by electromagnets MG. Since the electromagnets MG are large in size, they occupy a large space if arranged in one row. To reduce the space, therefore, odd-numbered actuators 30 each have the other arm 30b bent downwardly from one arm 30a thereof at right angles thereto, and the corresponding electromagnet MG is juxtaposed thereto. Thus each of the electromagnets MG which attracts the other arm 30b of each of the evennumbered actuators 30 is disposed below the other arm 30b extending straightforwardly from one arm 30a, so that each electromagnet MG attracting the other arm 30b of each even-numbered actuators 30 exerts its force of attraction in a direction at right angles to the direction in which each electromagnet MG attracting the other arm 30]) of each odd-numbered actuator 30 exerts exerts its force of attraction as shown in FIG. 4.

The one arm 30a of each actuator 30 has a front end portion 30c bent downwardly in key shape and having a pushup member 32 secured thereto. A spring 33 is mounted between the front end portion 30c of each actuator 30 and an immovable member (not shown) so as normally to urge the controller 30 to swing clockwise about shaft 31 by its biasing force. Thus, the other arm 30b of each actuator 30 is spaced apart from the associated electromagnet MG, and clockwise swinging of each actuator 30 is limited by one arm 30a abutting against a stopper 34. Another spring 35 is mounted between each trigger lever 26 and an immovable member (not shown) so as to urge each trigger lever 26 to swing counter clockwise about pivot 26a, and counter clockwork swinging of each trigger lever 26 is limited by the pin 27 maintained in contact with the edge of opening 5d as shown in FIG. 6.

Each trigger lever 26 is adapted to be flipped by the flip shaft 6 when the former moves into its operative position. More specifically, the flip shaft 6 juxtaposed to trigger lever 26 has a large diameter and is formed integrally in its periphery with a projecting edge 6a. Thus, when the flip shaft 6 rotates, a trigger lever 26 maintained in engagement with the periphery of the flip shaft 6 is flipped downwardly by the projectingedge 6a.

A hammering operation of each type hammer of the type hammer assembly constructed as aforementioned will now be described. Normally, the flip shaft 6 is rotated in the direction of an arrow C in FIG. 4, FIG. 5 and FIG. 6 by the aforementioned drive mechanism. When an electric pulse signal for causing the electromagnet to stand by for energization is generated by the sensing coil 21 shown in FIG. 2, a printing signal is produced by a logic circuit. This energizes the electromagnet MG associated with the figure to be printed. Energization of the electromagnet MG results in the other arm 30b of the actuator 30 associated with the particular electromagnet MG being attracted to the electromagnet, so that the actuator 30 swings counter clockwise in FIG. 6 about shaft 31 against the biasing force of spring 33 to the shown broken line position. Movement of the actuator 30 into the broken line position causes the pushup member 32 at the front end of one arm 30a to push and move upwardly the tail 260 of the associated trigger lever 26, so that the trigger lever 26 swings clockwise about its pivot 260 against the biasing force of spring 35. The range of swinging is limited by the pin 27 moving in the opening 5d till it is brought into contact with the edge of opening 5d. Swinging of the actuator 30 is also limited by the pin 27 being brought into engagement with the upper edge of opening 51!. Thus, the spacing between the other arm 30b and electromagnet MG can be adjusted suitably.

The aforementioned swinging of trigger lever 26 brings it to the broken line position in FIG. 6 in which the projection 26b is brought into contact with the periphery of the flip shaft 6. Soon after this, the projection 26b is flipped downwardly by the projection edge 6a of the rotating flip shaft 6. This results in the arm 50 of the associated type hammer 5 being pushed downwardly about pivot 26a, so that the type hammer 5 swings clockwise about shaft 25 against the biasing force of spring 29 and hammers on the printing sheet on the type cylinder 3. Thus, a predetermined figure or symbol is printed on the printing sheet.

The aforementioned hammering operation of the type hammer takes place very quickly. Since the flip shaft 6 rotates at high speed, printing speed is correspondingly very high. Thus, the precision of the electromagnet MG attracting the actuator 30 raises a problem. Generally, an electromagnet requires a rise time before it exerts a predetermined attraction after a current is passed through it, and a decay time before it is completely de-energized after the supply of current is cutoff. Preferably, the rise time and decay time are as short as possible. In the type hammer assembly, if the rise time is long, the projecting edge 6a will pass the flip position before the trigger lever 26 moves into'its operative position, so that no printing of a numeral or symbol will occur. If the decay time is long or if the electromagnet MG has excessive residual magnetic energy, trigger lever 26 will be maintained in the operative position even after printing is finished, so that the projecting edge 6a can flip the trigger lever 26 twice and cause double printing of a numeral or symbol to occur. It is thus desirable that the two times be minimized, though it is impossible to reduce them to zero.

This invention provides means for freeing the type hammers from the adverse influences of electromagnets. More specifically, when any type hammer 5 is moved clockwise in swinging motion about shaft 25 to hammer on a numeral or symbol, the trigger lever 26 mounted on the arm 50 of the particular type hammer also moves in swinging motion about shaft 25 with the type hammer as a unit. Thus, the arm 30a of actuator 30 which operates to push and move the trigger lever 26 upwardly is subjected to a force which is exerted in a direction in which the push-up force is exerted. This force tends to cause the actuator 30 to swing clockwise about shaft 31 against the attracting force of the electromagnet MG. Therefore, if the type hammer assembly is designed such that the electromagnet MG is deenergized when or immediately before the trigger lever 26 swings together with the type hammer 5, the actuator 30 will be forced to be restored to its original position mechanically as soon as the supply of current to the electromagnet MG is cut off. The controller thus restored to its original position will be retained in such position by the biasing force of spring 33.

In this way the controller is prevented from being actuated by the energizing force acting on the electromagnet during the decay time, or by residual magnetism in the electromagnet or by tackiness of the oil used to lubricate the mechanical parts, because the aforementioned return mechanism and the biasing force of the spring overcome the forces due to these causes. Upon restoration of the actuator 30 to its original position, the trigger lever 26 is also restored to its original position by the biasing force of spring 35. This moves the projection 26b completely out of the path of movement of the projection edge 6a of flip shaft 6, thereby preventing printing of the same figure or symbol twice. Since printing of the same figure or symbol twice is precluded by the return mechanism according to the invention, one has only to pay attention to the timing of energizing of each electromagnet MG so as to prevent a numeral or symbol.

As aforesaid, the hammering operation of each type hammer according to the invention is such that each type hammer and the trigger lever 26 associated therewith are normally independent of each other, but they act as a unit after the trigger lever 26 is caused to swing clockwise. Thus, the type hammer 5 performs hammering through the intermediary of the trigger lever 26. The actuator 30 which operates to move the trigger lever 26 into the path of movement of the projecting edge 6a of the flip shaft 6 is actuated by the electromagnet MG. Since the magnetic force of the electromagnet MG only serves to actuate the actuator 30 and the lever 26, and does not serve to force the type hammer 5 to operate, it is not required to have an electromagnet of high capacity. Moreover, since the movement of the trigger lever 26 is limited by the stopper 27 on the type hammer 5, the need to provide a guide for the trigger lever 26 or an additional stop for controlling the movement of the trigger lever 26 is eliminated, thereby permitting to reduce the size of the type hammer assembly.

The feed mechanism for the ribbon 9 interposed between the type hammers 5 of the type hammer assembly and the type cylinder 3 and hammered by each type hammer on to the type cylinder 3 will now be described.

As shown in FIG. I, this mechanism is disposed between the two base plates 1 and 2 and arranged rearwardly and upwardly of the type hammer assembly. Mounted between base plates 1 and 2 is a horizontal support plate 40, which is best shown in an exploded view in FIG. 7. The horizontal support plate 40 is formed in the central portion of its upper edge, or the edge nearer to the type hammers, with an inward cutout 40a which serves as a guide path for the movement of a change-over plate 41 as subsequently to be described. Two

cutouts

40b and 400 of a larger width than cutout 40a are formed symmetrically with respect to cutout 40a on the left and on the right thereof.

Cutouts

40b and 400 are adapted to receive therein depending portions 41a and 41b respectively of the change-over plate 41, which are formed in the left and right wings in the upper portion of the plate 41.

The support plate is also formed at the left and right corners of the upper edge thereof with inwardly bent

inclined edges

40d and 40e respectively which face each other. Ribbon guides 42 and 43, subsequently to be described, are adapted to come into contact with

inclined edges

40d and 40e respectively. The support plate 40 is formed in the central portions of the left and right side edges thereof with downwardly bent depending

portions

40f and 40g respectively which are secured by rivet shafts 44 and 45 (See FIG. 2 and FIG. 3) to left and right base plates I and 2 respectively so as to hold the horizontal support plate 40 in place between base plates 1 and 2.

The support plate 40 is also formed, at the comers of the left and right side edges nearer to the lower edges thereof, with upwardly bent rise portions 40h and 401' respectively, which pivotally support

bases

46a and 47a or ribbon

color switching arms

46 and 47 respectively. The switching

arms

46 and 47 extend from their bases toward the type cylinder 3, and their free end portions are interconnected by a connector 48. The

arms

46 and 47 are formed on the underside of their free ends with inwardly

bent projections

46b and 47b respectively, which support thereon upright

ribbon guide shafts

49 and 50 respectively.

A substantially rectangular opening 40j is formed downwardly of the central portion thereof for receiving therein a connecting pin 51 connected to a tail end 41c of the change-over plate 41 to face downwardly. A loop spring 52 (See FIG. 9), subsequently to be described, is mounted on pin 51. Reel support

upright shafts

53 and 54 are arranged on the support plate 40 and disposed symmetrically on left and right of opening 40j with respect thereto.

Ratchet wheels

57 and 58 are rotatably mounted on

shafts

53 and 54 through plate springs 55 and 56 respectively. The

ratchet wheels

57 and 58 are formed on their peripheries with teeth which are oriented in opposite directions. Thus, when they are moved by respective pawls, as subsequently to be described, one ratchet wheel 57 rotates counter clockwise about support shaft 53, while the other ratchet wheel 58 rotates clockwise about support shaft 54. The

ratchet wheels

57 and 58 are formed in their bodies with three

openings

57a and 58a respectively which are disposed equidistantly from one another with respect to the

shafts

53 and 54. Pins 7a and 8a, which are formed integrally on the underside of ribbon reels 7 and 8 (See FIG. 8) mounted on shafts S3 and 54 re spectively, are adapted to be received in

openings

57a and 58a. Thus, when the ratchet wheels rotate, the reels rotate intermittently to feed the ribbon from one reel to the other reel. E-rings 59 and 60 are mounted on

shafts

53 and 54 respectively so as to preclude dislodging of the plate springs 55 and 56 and ratchet

wheels

57 and 58 which are mounted on

shafts

53 and 54 respectively.

The lower end portions of

support shafts

53 and 54 extend downwardly through the support plate 40 and support the ribbon guides 42 and 43, at their bases 42a and 43a respectively, for swivel motion. The ribbon guides 42 and 43 have free end portions 42b and 43b respectively which extend toward the tape cylinder 3. The free ends of ribbon guides-42 and 43 are bent upwardly to form rise portions 420 and .43c're spectively which rise about the level of horizontal support plate 40, each of

rise portions

420 and 430 being bent in the middle in the form of a letter L in section.

Vertical slits

61 and 62 are formed in the bent portions of

rise portions

42c and 43c respectively for guiding the ribbon 9 which moves therethrough.

The ribbon guides 42 and 43 constructed as aforementioned are formed in the inner lateral edge of free end portions 42b and 43b with depending portions 42e and 432 respectively which are pulled outwardly by springs 63 and 64 respectively, so that the

guides

42 and 43 diverge in going toward the free ends, and the

rise portions

420 and 430 are urged toward being positioned against the

inclined edges

40d and 40e of supporting plate 40 respectively (See FIG. 1, FIG. 8 and FIG. 11). Depending portions 42d and 43d are also formed in the inner lateral edge of free end portions 42b and 43b of ribbon guides 42 and 43 respectively to perform the function of pushing and moving connect-' in

g arms

65 and 66 respectively when the

guides

42 and 43 swivel about

support shafts

53 and 54 respectively.

The connecting

arms

65 and 66 have bases 65a and 66a disposed below the ribbon guides 42 and 43 and pivotally connected to

shafts

53 and 54 respectively. A spacer washer 67 and an E-ring 68 are mounted on shaft 53 to prevent dislodging of connecting arm 65 and ribbon guide 42 downwardly from support shaft 53, while a stopper ring 69 and an E-ring 70 are mounted on shaft 54 to prevent dislodging of connecting arm 66 and ribbon guide 43 downwardly from support shaft 54.

The connecting

arms

65 and 66 have horizontal

free end portions

65b and 66b respectively which extend toward the type cylinder 3 and further outwardly from the underside of the upper edge of support plate 40. The

free end portions

65b and 66b are bent upwardly at their free ends to form rise portions 650 and 660 respectively. Change-over plate switching members or

claws

71 and 72 are pivotally mounted on the connecting

arms

65 and 66 through

pins

73 and 74 respec tively, and their tail ends are bent downwardly to form depending portions 71a and 72a respectively which extend inwardly of the connecting

arms

65 and 66 respectively. Compression springs 75 and 76 are mounted between the depending portions 71a and 72a of

claws

71 and 72 and downwardly bent portions 65d and 66d formed in the outer lateral edge of connecting

arms

65 and 66 respectively.

Thus, change-over plate switching member 71 is normally urged to move clockwise about pin 73 while claw 72 is normally urged to move counterclockwise about shaft 74. The movements of

claws

71 and 72 are limited by their front edges abutting against the rise portions 650 and 66c of connecting

arms

65 and 66 respectively. Sharp portions 71b and 72b are formed in the inner lateral edges of

claws

71 and 72 respectively to face each other.

The connecting

arms

65 and 66, on which

claws

71 and 72 are mounted in this way, are connected to each other by a spring 77. Thus, connecting arm 65 is normally urged to move clockwise about support shaft 53 while connecting arm 66 is normally urged to move counterclockwise about support shaft 54. The movements of connecting

arms

65 and 66 are limited by the inner lateral edges thereof abutting against the depending portions 42e and 43e of

guides

42 and 43, which are pulled outwardly by springs 63 and 64 respectively. The resilience of the springs 63 and 64 is greater than the resilience of spring 77 (See FIGS. 11). Thus, the connecting

arms

65 and 66 normally extend toward the type cylinder 3.

A change-over plate moving member 78 is disposed parallel to the connector 48 below the horizontal support plate 40 and in the vicinity of support shaft 54. Member 78 is pivotally supported by a shaft 79 connected to support'plate 40, and includes an inwardly extending arm 78a, which pivotally supports at its end one end 80a of a connecting bar 80, which is disposed at right angles to moving member 78. The other end 80b of connecting bar 80 is disposed below the cutout 40a formed in support plate 40 and fixed to a shaft 82 extending downwardly from the head of changeover plate 41 through cutout 40a.

A roller 83 formed with a peripheral groove 83a is mounted on shaft 82 such that the edge of cutout 40a is received in' the peripheral groove 83a of roller 83. Thus, when the moving member 78 pivots counterclockwise, the changeover plate 41 is moved into cutout 40a through connecting bar 80. The change-over plate 41 which is formed in the left and right wings thereof with downwardly bent depending portions 41a and 41b is also formed on the left and right sides of its tail 410 with feed pawls 41a and 41b respectively. The change-over plate 41 moves when the left feed pawl 41d engages ratchet wheel 57, so that the ratchet wheel 57 is intermittently moved a distance corresponding to one tooth counter clockwise about shaft 53. When the right feed pawl 41c engages ratchet wheel 58, the movement of changeover plate 41 causes the ratchet wheel 58 to move intermittently a distance corresponding to one tooth clockwise about shaft 54. A loop spring 52, as shown in FIG. 9, is mounted between a connecting pin 51 secured to the tail 41c of changeover plate 41 and shaft 81. Accordingly, the tail 41c oscillates about shaft 82 and deviates either to right or left from a straight

line connecting shafts

81 and 92 to each other. As a result, one of the feed pawls is brought into engagement with the respective ratchet wheel. In FIG. 9, the change-over plate 41 is shown as having been pivoted clockwise about shaft 82 by the biasing force of loop spring 52 to bring the left feed pawl 41d into engagement with ratchet wheel 57. Thus, when the change-over plate 41 moves in this manner, left ratchet wheel 57 rotates counterclockwise.

As shown in FIG. 8, a return check pawl 84d engages ratchet wheel 57. A return check pawl support 84 has a base 84a that is pivotally supported by a shaft 85 connected to support plate 40, and a free end portion which extends above the change-over plate 41. A pin 86 is connected to thefront end of the free end portion, and a loop spring 88 is mounted between the pin 86 and an immovable pin 87. The pin 87 is disposed on the support plate 40 in a position disposed on a straight line connecting shafts 82 and to each other, and extends upwardly through a square opening 41f formed in the changeover plate 41.

Branches

84b and 84c are fonned integrally with the return check pawl support 84 and extend from opposite sides thereof which are juxtaposed to ratchet

wheels

57 and 58 respectively. The front ends of the left and

right branches

84b and 84c are bent downwardly to form return check pawls 84d and 842 which are adapted to engage

ratchet wheels

57 and 58 respectively. The left return check pawl 84d, formed on the left side of support 84, prevents ratchet wheel 57 from rotating clockwise about support shaft 53 when the former is in engagement with the ratchet wheel, while the right return check pawl 84e, formed on the right side of support 84, prevents ratchet wheel 58 from rotating counterclockwise about support shaft 54 when the former is en engagement with the ratchet wheel. The return pawl sup port 84 is adapted to be caused, by the action of the changeover plate 41, to have its free end portion incline toward the ratchet wheel with which the feel pawl is in engagement, so that the return check pawl is in engagement therewith too. In FIG. 8, the free end of return check pawl support 84 is inclined toward the ratchet wheel 57 with which the feed pawl 41d is maintained in engagement, so that the return check pawl 84d is maintained in engagement with ratchet wheel 57 too, thereby preventing the ratchet wheel from rotating clockwise.

Referring to FIG. 1, a pair of reel keep

members

207 and 208 are pivotally supported, at their bases 207a and 208a, by shaft 85. A spring 209 is mounted between bent portions 20717 and 208 formed in reel keep

members

207 and 208 respectively, so that inner surface of one reel keep member 207 is maintained in light pressing engagement with the periphery of reel 7 and the inner surface of the other reel keep member 208 is maintained in light pressing engagement with the pe riphery of reel 8. The reel keep

members

207 and 208 perform the function of preventing excess rotation of the reels due to inertia when the reels rotate.

Referring to FIG. 7, the change-over plate 41 is moved through the connecting bar 80 as the moving member 78 oscillates about support shaft 79. The mov ing member 78, which moves the connecting bar 80, has an outwardly extending end portion 78b which is bent downwardly to form a bent depending portion 780 formed therein with an opening 78d for receiving therein a pin 89 connected to one arm 90a of a pivotal lever 90. As shown in FIG. 3, the pivotal lever 90 is disposed outwardly of right base plate 2 and is pivotally supported by a shaft 91, and the inwardly directed pin 89 is connected to one arm 90a extending upwardly from shaft 91 through a square opening 2a formed in the right base plate 2 and the opening 78d formed in the pivotal lever 78.

Referring to FIGS. 3 and 7, the pivotal lever 90 has the other arm 90b which extends obliquely downwardly and ends in a form 900 for receiving therein a pin 93 connected to one arm 92a of a slide lever 92 which is formed in its central portion with a longitudinal slot (not shown). The slide lever 92 is held in place as the end portion of the shaft 25 extending outwardly through the right base plate 2 and received the slot. Thus, the slide lever 92 is inclined obliquely right wardly upwardly and disposed outwardly of the right base plate 2.

Formed at the end portion of a portion of the slide lever 92 extending obliquely leftwardly downwardly is a fork 92b for receiving therein a pin 94 connected to the right base plate 2. The portion in which the form 92b is formed further extends downwardly to form an extension 92c to which a pin 93 is connected. Thus, when the slide lever 92 moves longitudinally thereof, the pivotal lever 90 is caused, through pin 93, to oscillate about support shaft 91. Longitudinal reciprocating motion of the slide lever 92 is caused to take place by the pivoting of a bell-crank which is pivotally supported by a shaft 96 connected to the right base plate 2.

The bell-crank 95 has one arm 95a which is formed therein with a slot 95b for receiving therein a pin 97 connected to one arm 92a of the slide lever 92, and the other arm 950 which is formed therein with a fork (not shown) for receiving therein an eccentric cam (not shown). The eccentric cam is mounted on a shaft 99 supporting a gear 98 to which rotation is transmitted from the aforementioned gear 13. Rotation of gear 98 is transmitted to the eccentric cam through a clutch (not shown) which is normally rendered inoperative by a stopper 100 and a stopper lever 101, but is actuated when an electromagnet 102 is energized to attract the stopper 100 thereto, so that rotation of gear 98 can be transmitted to the eccentric cam. Actuation of the eccentric cam causes the bell-crank 95 to oscillate about support shaft 96 as indicated by arrows P, so that the slide lever 92 is reciprocated longitudinally thereof by the pin 97 connected to one arm 95a of the bell-crank 95.

Referring to FIG. 1, a feed pawl 103 is mounted at the other arm 92d of the slide lever 92 and performs the function of intermittently rotating the printing sheet feed roller 4. More specifically, roller 4 is mounted on a rotary shaft 104 disposed between the left and right base plates 1 and 2 and supported thereby, one end portion 104a of shaft 104 extending outwardly through the right base plate 2 and mounting thereon, as shown in FIG. 3 a ratchet wheel 105 which is engaged by the feed pawl 103. Thus, the pawl 103 moves the ratchet wheel 105a distance corresponding to one tooth as the slide lever 92 makes one reciprocating motion, so that the printing sheet feed roller 4 is intermittently rotated to feed a printing sheet (not shown).

Operation of the ribbon feed mechanism constructed as aforementioned will now be described. The ribbon 9 used in this embodiment is fixed at opposite ends thereof to

reels

7 and 8. That is, the starting end of ribbon 9 is secured to a shaft for supporting reel 7 while the terminating end thereof is secured to a shaft for supporting reel 8. The ribbon 9 payed out from reel 7 is passed through the

slits

61 and 62 formed in ribbon guides 42 and 43 respectively and trained between the type cylinder 3 and type hammers 5 through ribbon guide shafts 49 and 50 (See FIG. 1).

Assuming that instructions to feed the ribbon are given to the electromagnet 102, the electromagnet attracts the stopper 100 and actuates or engages the clutch, so that rotation of gear 98 is transmitted to the eccentric cam to rotate the same. Rotation of theeccentric cam causes the bell-crank 95 to move clockwise about support shaft 96. Clockwise movement of the bell-crank 95 causes the slide lever 92 to move, through the pin 97 mounted on one arm 95a, obliquely rightwardly upwardly in FIG. 3. This movement of the slide lever 92 results in the feed pawl 103 causing the ratchet wheel 105 to rotate clockwise, thereby rotating roller 4 to feed the printing sheet. At the same time, the movement of the slide lever 92 causes the pivotal lever 90, through the pin 93 connected to the slide lever 92, to move clockwise about support shaft 91. This movement of the lever 90 causes the moving member 78, through the pin 89 connected to one end 90a, to move counter clockwise about support shaft 79 in FIG. 9.

This movement of the moving member 78 pulls the counting bar 80, which is connected to one end 78a thereof, outwardly or downwardly in FIG. 9. This re sults in the change-over plate 41, which is connected to the moving member 78 through the shaft connected to the connecting bar 80, being pulled downwardly too.

Downward movement of the change-over plate 41 causes the feed pawl 41d, which is formed integrally with the change-over plate 41 and is maintained in engagement with ratchet wheel 57, to be released from engagement with one tooth of ratchet wheel 57 and brought into engagement with a preceding tooth thereof. Thereafter, as the bell-crank 95 moves in the reverse direction, or counter clockwise, about support shaft 96, the slide lever 92 moves obliquely leftwardly downwardly in FIG. 3. This movement of the slide lever 92 causes the pivotal lever 90 to move clockwise about shaft 91. This causes the moving member 78, through pin 89, to move clockwise about support 'shaft 79. This moves the connecting bar 80 upwardly, as shown in FIG. 10, thereby moving the change-over plate 41 upwardly through shaft 82.

Upward movement of the change-over plate 41 causes the feed pawl 41d to move ratchet wheel 57 counterclockwise about support shaft 53, thereby rotating reel 7 counterclockwise. Thus, the reel 9 is moved from reel 8 to reel 7 a distance corresponding to one tooth of ratchet wheel 7. In this way, ribbon 9 is intermittently moved as the slide bar 92 makes one reciprocating motion.

As the ribbon 9 fed from reel 8 draws near the tenninating end thereof, ribbon 9 is tensioned between ribbon guide shaft 50 and the shaft for reel 8 to which the end of ribbon 9 is secured. If the ribbon is formed therein with an eyelet, the eyelet will be caught by either slit 61 or 62, and guide 42 and 43 will swing.

Slits

61 and 62 may be formed in round shafts. If this is the case, however, a ribbon having an eyelet cannot be used with the printer. The provision of

slits

61 and 62 permits both types of ribbon to be used.

When ribbon 9 is tensioned as aforementioned, the ribbon guide 43 which guides the ribbon moves counterclockwise about shaft 54 as shown in FIG. 12 against the biasing force of spring 64. The counterclockwise movement of guide 43 causes the depending portion 43d of guide 43 to push and move connecting arm 66, so that the claw 72 on the arm moves into the path of movement of the bent depending portion 41b of the change-over plate 41. Thus, when the change-over plate 41 moves downwardly, its bent depending portion 41b abuts against claw 72 and change-over plate 41 is caused to move counterclockwise about shaft 82, as shown in FIG. 13, because the point at which portion 41b abuts claw 72 serves as a pivot for an instant. This brings the feed pawl 41c into engagement with ratchet When the changeover plate 41 moves counterclockwise as aforementioned, tail end 410 thereof flips the return check pawl 84e formed on the branch 84c of return check pawl support 84, so that the return check pawl support 84 moves clockwise about support shaft 85. This brings return check pawl 84c into engagement with ratchet wheel 58 by virtue of the biasing force of loop spring 88, as shown in FIG. 14.

In this way, the ribbon feed mechanism according to the invention permits the change-over plate 41 to be wheel 58 by virtue of the biasing force of loop spring automatically released from one ratchet wheel 57 and brought into engagement with the other ratchet wheel 58 to reverse the direction of movement of the ribbon when all the ribbon is moved from reel 7 to reel-8. It will be understood that, after the change-over plate is switched from one ratchet wheel to the other ratchet wheel, return check pawl 41e intermittently rotates ratchet wheel 58 clockwise each time the slide lever 92 makes one reciprocating motion.

When claw 72 is moved into the path of movement of the change-over plate 41 after the latter has completed its downward movement, depending portion 41b pushes claw 72 upwardly and moves the same clockwise about shaft 74 against the biasing force of spring 76, while depending portion 41b moves upwardly so as to temporarily move claw 72 out of the path of movement of depending portion 41b. Claw 72 is restored to its position in the path of movement of depending portion 41b by the biasing force of spring 76 after depending portion 41 has completed its upward movement, so that the change-over plate 41 can be switched while depending portion 41 moves downwardly.

A ribbon color switching mechanism for switching the printing ribbon 9 between two colors will now be described. The printing ribbon 9 used in this embodiment consists of two portions as shown in FIG. 2 and FIG. 3, one portion being an upper half 9a of the ribbon and black in color and the other half portion being a lower portion 91) of the ribbon and red in color. Normally, the black half 9a of the ribbon is indexed with the type hammer assembly.

Referring to FIGS. 2 and 3, an outwardly directed pin 106 is connected to the free end portion of one ribbon color switching arm 46 to which ribbon guide-shaft 49 is connected as shown in FIG. 2. Pivotally connected to pin 106 is one end portion 107a of a vertically disposed connecting rod 107, which has the other end portion 107b depending therefrom outwardly of left base plate 1 and formed as a larger width portion 1076 at its end. A vertically disposed slot 108 is formed in the larger width portion 107( for receiving therein a shaft 109 extending outwardly from left base plate 1. A spring 111 is mounted between the larger width portion 107(- and a pin connected to the upper portion of left base plate 1 so as to urge connecting rod 107 to move upwardly by its biasing force.

The upward movement of connecting rod 107 is normally prevented by a stop arm 112 pivoted at an arm 113 extending outwardly from the outer upper portion of left base plate 1. The stop arm l12 has a free end portion 112a which extends downwardly parallel to connecting rod 107, and is bent at its front end toward connecting rod 107 to form an engaging portion 112b. A spring 114 is mounted between the free end portion 112b of stop arm 112 and shaft 109 to urge stop arm 112 to pivot clockwise about shaft 113. However, this movement is prevented by the engaging portion 1l2b of stop arm 1 12 engaging the larger width portion 1070 of connecting rod 107.

The side edge of larger width portion 107e, engaged by engaging portion 112b, is bent downwardly at its lower portion toward left base plate 1 to form a bent portion 107d abutting against engaging portion 112b.

An electromagnet 115 adapted to be energized when a ribbon color switching signal, is produced is disposed near the free end portion 112a of stop arm 112, or rightwardly of free end portion 112a in FIG Z. The

electromagnet 1 15, which is mounted on left base plate 1, attracts the free end portion 112a of stop arm 112 thereto when energized, thereby releasing bent portion 107d from engagement by engaging portion 112b. Upon bent portion 112d being released from engaging portion 112b, the connecting rod 107 is moved upwardly by the biasing force of spring 111 and pushes ribbon color switching arm 46 upwardly into a position shown in FIG. 15. The other ribbon color switching arm 47 is also pushed upwardly through the connector 48 into its upper position, so that the ribbon 9 is moved upwardly and the lower red portion 9b is indexed with the type hammers while the upper black portion 9a is moved upwardly out of index with the type hammers.

Means is provided for automatically restoring the ribbon 9 to its original position in which the upper black portion 9a is indexed with the type hammers when the electromagnet 115 is de-energized. This is accom-' plished by a pin 116 connected to the other ribbon color switching arm 47 and a bell-crank 117. More specifically, the pin 1 16 extending outwardly from the free end portion 47b of the other ribbon color switching arm 47, as shown in FIG. 3 and FIG. 7, is received in a fork l17b formed at the end of one arm 117a of bellcrank 117 pivotally supported by rivet shaft 45 and disposed outwardly of right base plate 2, as shown in FIG. 3. The other arm 117(' of bell-crank 117 extends at right angles to slide lever 92 and its front end extends between right base plate 2 and slide lever 92.

A pin 118 is connected to slide lever 92 to extend rightwardly of slide lever 92 in FIG. 3 toward right base plate 2. Pin 118 performs the function of pushing and moving the other arm 117C of bell-crank 117 about shaft 45. More specifically, when ribbon color switching arm 47 moves in pivotal motion, bell-crank 117 is caused, through pin 116, to move counterclockwise about shaft 45. This moves the other arm 1170 into engagement with pin 118. If slide lever 92 makes a reciprocating motion at this time, pin 118 pushes and moves the other arm 117C and causes bell-crank 117 to move clockwise about shaft 45 when slide lever moves obliquely leftwardly downwardly. Clockwise movement of bell-crank 117 causes ribbon

color switching arms

46 and 47 through pin 116 to move downwardly from their upper positions shown in FIG. 15, so that the upper black portion 9a of ribbon 9 is indexed with the type hammers.

If the electromagnet 115 remains de-energized at this time, downward movement of ribbon color switching arm 46 results in the connecting rod 107 moving downwardly, with the result that the bent portion 107d of larger width portion l07c is engaged and locked by the engaging portion [12b of stop arm 112. Thus, the ribbon 9 which is switched from black to red is automatically switched to black again. However, if the electromagnet 115 remains energized at this time, the ribbon

color switching arms

46 and 47 are moved upwardly again by the biasing force of spring 111 after moving downwardly, so that the lower red portion 9d of ribbon 9 is indexed with the type hammers.

The aforementioned ribbon color switching mechanism is provided with an elevating mechanism for use when the old ribbon is replaced by a new ribbon. As shown in FIG. 2, a stop arm moving arm 119 is secured at its base to stop arm 112, and a spherical pusher 120 is secured to the front end portion of arm 119. The

moving arm 119, which is secured at its base to the base of stop arm 112, has a free end portion extending upwardly, in a direction opposite to the direction in which the free end portion of stop arm 112 extends, and supporting the spherical pusher at its end.

When the old ribbon is replaced by a new ribbon the reels are removed from the support shafts before replacement is effected. Ribbon 9 can be removed more readily when the red portion 9b is indexed with the type hammers because the ribbon is in its upper position. Thus, the old ribbon can be readily replaced by a new ribbon if the ribbon 9 is moved manually to the upper position, even if the calculator is disconnected from the power source. The ribbon 9 can be moved manually to the upper position if pusher 120 is moved in the direction of an arrow F in FIG. 2.

Movement of pusher 120 in the direction of arrow F results in both stop arms 112 and pusher 120 moving counterclockwise about shaft 113 in FIG. 15, thereby releasing engaging portion 1 12b from engagement with bent portion 107d. This permits the connecting rod 107 to be moved upwardly by the biasing force of spring 111, so that ribbon color switching arm 46 moves in pivotal motion and the ribbon 9 moves upwardly into its upper position. Thus, replacement of the old ribbon of a new ribbon can be facilitated.

I claim:

1. A flying parallel printer for a table electronic calculator comprising: a type cylinder, a plurality of type hammers each having an upper end carrying a type symbol, means for pivotally supporting the type hammers with the symbol carrying upper ends thereof facing the type cylinder and movable between a rest position away from the type cylinder and a printing position against the type cylinder, means for biasing each type hammer toward its rest position, a plurality of trigger levers each associated with an individual type hammer, means for pivotally securing each trigger lever to its associated type hammer, means for limiting the relative motion of each trigger lever with respect to its associated type hammer to a defined range whose boundaries are defined by a typing position and a rest position of the trigger lever, means for biasing each trigger lever towards its rest position, a plurality of actuators each associated with an individual trigger lever and each carrying a push up member, means for pivotally supporting the actuators for movement of each actuator between a typing position in which its push up member engages the associated trigger lever and moves it to its typing position and a rest position in which it does not so engage the associated trigger lever, means for biasing each actuator toward its rest position, means for moving selected actuators to their typing positions to thereby move the associated trigger levers to their typing positions, and means for pivoting each trigger lever which is in its typing position against the force of its biasing means to cause it to engage and move the associated type hammer to its typing position, with the symbol carrying upper end of the type hammer against the type cylinder, wherein the means for limiting the relative motion between each trigger lever with respect to its associated type hammer comprises means defining an opening in one of the associated pair of a hammer and a lever and a pin extending from the other one of said associated pair of a hammer and a lever into said opening and engaging one side wall of said opening when the trigger lever is in its typing position and engaging an opposite side wall of said opening when the trigger lever is in its rest position.

2. A printer as in claim 1 wherein the means for pivotally supporting the actuators comprises a shaft and each actuator comprises a forward arm extending in a forward direction from said shaft and carrying said push-up member and a back arm extending in a different direction from said shaft in operative proximity to the means for moving selected actuators to be selectively engaged and moved thereby.

3. A printer as in claim 2 wherein the back arms of each adjacent pair of actuators extend in two different directions, with the back arms of alternating actuator members extending in the same direction from said shaft.

4. A printer as in claim 3 wherein the means for moving selected actuators comprises a plurality of electromagnets each associated with an individual actuator, said electromagnets disposed in two rows parallel to the shaft supporting the actuators, with each adjacent pair of electromagnets of each row associated with a pair of actuators separated from each other by a single actuator.

5. A printer as in claim 4 wherein each alternating actuator of a first sequence of alternating actuators is L- shaped, and each actuator of a second sequence of alternating actuators is substantially straight.

6. A flying parallel printer for a table electronic calculator comprising: a type cylinder, a plurality of type hammers each having an upper end carrying a type symbol, means for pivotally supporting the type hammers with the symbol carrying upper ends thereof facing the type cylinder and movable between a rest position away from the type cylinder and a printing position against the type cylinder, means for biasing each type hammer toward its rest position, a plurality of trigger levers each associated with an individual type hammer, means for pivotally securing each trigger lever to its associated type hammer, means for limiting the relative motion of each trigger lever with respect to its associated type hammer to a defined range whose boundaries are defined by a typing position and a rest position of the trigger lever, means for biasing each trigger lever towards its rest position, a plurality of actuators each associated with an individual trigger lever and each carrying a push up member, means for pivotally supporting the actuators for movement of each actuator between a typing position in which its push up member engages the associated trigger lever and moves it to its typing position and a rest position in which it does not so engage the associated trigger lever, means for biasing each actuator toward its rest position, means for moving selected actuators to their typing positions to thereby move the associated trigger levers to their typ ing positions, and means for pivoting each trigger lever which is in its typing position against the force of its biasing means to cause it to engage and move the associated type hammer to its typing position, with the symbol carrying upper end of the type hammer against the type cylinder, said pivoting means comprising a rotating flip shaft having a radially extending projecting edge for engaging during each revolution of the flip shaft each trigger lever which is in its typing position and positively moving during the same revolution the type hammer associated with each engaged trigger lever from the rest position to the typing position thereof.

7. A printer as in claim 6 wherein the means for moving selected actuators comprises a plurality of electromagnets each associated with an individual actuator.

8. A printer as in claim 6 wherein the means for limiting the relative motion between each pair of a type hammer and an associated trigger lever comprises means defining an opening in one of said hammer and an associated lever and a pin extending from the other one of said pair of a hammer and an associated lever extending into said opening and engaging one side wall of the opening when the trigger lever is in its typing position and engaging an opposite side wall of said opening when the trigger lever is in its rest position.

9. A printer as in claim 6 wherein each actuator is centrally pivoted and comprises a forward arm carrying said push-up member and extending forwardly of the pivot and a back arm extending in a different direction from said pivot in operative proximity to the means for moving selected actuators to be selectively engaged and moved thereby.

10. A printer as in claim 9 wherein the back arms of a first sequence of alternating actuators point in a first direction and the back arms of a second alternating sequence of actuators point in a different second direction.

11. A printer as in claim 10 wherein the means for moving selected actuators comprises a plurality of electromagnets each associated with an individual actuator,

said electromagnets arranged in two rows each aligned with the back arms of each alternating sequence of actuators.

Claims

5. A printer as in claim 4 wherein each alternating actuator of a first sequence of alternating actuators is L-shaped, and each actuator of a second sequence of alternating actuators is substantially straight.

6. A flying parallel printer for a table electronic calculator comprising: a type cylinder, a plurality of type hammers each having an upper end carrying a type symbol, means for pivotally supporting the type hammers with the symbol carrying upper ends thereof facing the type cylinder and movable between a rest position away from the type cylinder and a printing position against the type cylinder, means for biasing each type hammer toward its rest position, a plurality of trigger levers each associated with an individual type hammer, means for pivotally securing each trigger lever to its associated type hammer, means for limiting the relative motion of each trigger lever with respect to its associated type hammer to a defined range whose boundaries are defined by a typing position and a rest position of the trigger lever, means for biasing each trigger lever towards its rest positioN, a plurality of actuators each associated with an individual trigger lever and each carrying a push up member, means for pivotally supporting the actuators for movement of each actuator between a typing position in which its push up member engages the associated trigger lever and moves it to its typing position and a rest position in which it does not so engage the associated trigger lever, means for biasing each actuator toward its rest position, means for moving selected actuators to their typing positions to thereby move the associated trigger levers to their typing positions, and means for pivoting each trigger lever which is in its typing position against the force of its biasing means to cause it to engage and move the associated type hammer to its typing position, with the symbol carrying upper end of the type hammer against the type cylinder, said pivoting means comprising a rotating flip shaft having a radially extending projecting edge for engaging during each revolution of the flip shaft each trigger lever which is in its typing position and positively moving during the same revolution the type hammer associated with each engaged trigger lever from the rest position to the typing position thereof.

11. A printer as in claim 10 wherein the means for moving selected actuators comprises a plurality of electromagnets each associated with an individual actuator, said electromagnets arranged in two rows each aligned with the back arms of each alternating sequence of actuators.