Printing Device With Interchangeable Printing Members

Abstract

A printing device comprising a continuously rotating disc having a plurality of flexible type carrying segments and a hammer for causing individual segments to move into contact with a paper on a platen. Control means are provided for actuating the hammer at the proper instant relative to the constantly rotating disc so that the preselected character is printed.

Description

CROSS REFERENCES TO RELATED APPLICATION

Applicant claims priority from corresponding Italian Patent application Ser. No. 50314-A/68 filed Jan. 29, 1968.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a high-speed serial printing device for typewriters, teleprinters, calculators, accounting machines and similar office machines, including a disc of elastically flexible material in constant rotation and having one or more series of types distributed around one or more respective circumferential zones, the disc being subdivided into equal sectors each of which carries a type for the or each of the said zones. A hammer is adapted to be actuated under the control of an input code to effect the rapid printing of the characters of said disc when the disc has been correctly positioned.

2. Description of the Prior Art

Printing devices of this kind are known in which the type disc is unremovable and therefore permits only a single kind of printing corresponding to the series of types carried by it. The art of printing for office purposes, however, often requires the use of kinds of printing types which differ according to the characteristics of the printing sheet, for which reason it is necessary to have available a plurality of machines of the kind described or it is necessary to resort to machines of a different kind. Moreover, in the case where the printing device is fed by machines which operate with different codes, it will always be necessary to interpose a code converter between the feeding machine and the printing device, which operates with its own fixed code, and this makes the use of the printing device complicated and costly.

SUMMARY OF THE INVENTION

The object of the invention is to avoid these drawbacks and to provide a serial printing device which is adapted to operate at high speed with the maximum simplicity and reliability of operation.

According to the present invention there is provided a printing device comprising a flat or dished type disc mounted on a support, and paper support means, the disc support or the paper support means being movable to provide for serial printing from the disc along a line on the paper, the disc being of elastically flexible material slotted to provide a plurality of equal sectors, each of which carries one or more types in one or more corresponding circumferential zones of the disc, the device further comprising a hammer for striking a selected sector to effect printing, means for rotating the disc continuously, and means for providing signals indicative of the angular position of the disc for comparison with input code signals to determine the instant of operation of the hammer, the disc being mounted removably on the disc support and interchangeably with other type discs.

Moreover, in the known printing devices of the kind described there is a certain friction between the sector-like tongue or strips of the disc and the striking hammer if the arrangement is not properly timed and well adjusted so that the time for the striking of said hammer on a tongue and the rebound of the hammer is less than the time taken by the type disc to perform a rotation equal to the angle occupied by a sector-like tongue. In order to avoid fouling or obstruction between the hammer and the tongues of the disc, with resultant damage to the tongues themselves it is further proposed that the hammer has a head which is articulated and held in the position suitable for rapid printing by means of a return spring.

Another disadvantage of the known printing devices of the kind described is that the movement of a type whose tongue has been rapidly struck by the hammer is oblique with respect to the printing plane, inasmuch as it is the result of the compounding of two movements, that is the constant rotation of the disc and the movement perpendicular to the disc itself owing to the effect of the bending of the tongue. Therefore, since each type carried by a tongue does not have a movement exclusively perpendicular to the printing plane, it drags partially on the latter with detriment to the distinctness of the impressed characters. In order to obviate this drawback the sectors can also be flexible in the circumferential direction, so that at the instant of impact with the printing sheet each type tongue can be checked so as to render the dragging with respect to the printing sheet very slight and thus avoid smudging of the print.

Finally, in a known printing device of the kind described in which said disc is carried by a transversely movable carriage, step-by-step advance of the carriage is effected by a screw set in motion by the continuous rotation of a motor by means of a friction clutch and arrested in the successive printing positions by means of a ratchet gear controlled by an electromagnet, the control of this electromagnet being effected by means of a special control device. This device, however, still has the disadvantage of requiring two separate devices for controlling the striking of the selected type and for the movement of advance. This disadvantage can be obviated in that signals generated by the rotation of the type disc control the electromagnet.

BRIEF DESCRIPTION OF THE DRAWINGS:

The invention will be described in more detail, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of one embodiment of a printing device according to the invention;

FIG. 2 is a front view of the type disc and associated parts included in the printing device of FIG. 1;

FIG. 3 is a cross-sectional view taken along line III--III of FIG. 2; and

FIG. 4 is a perspective view of a second embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

Referring to FIG. 1, the printing device includes a printing roller or platen 1, on which there lies a printing sheet 2, and also a carriage 3 movable transversely of the printing sheet along a guide 4.

The carriage 3 runs on the guide 4 by means of rollers 5 mounted on ball bearings and is drawn along by a screw 6 engaging with a nut screw 34 fast with the carriage. Mounted on the carriage is a pulley 7 rotatable on a spindle 8 and rotated by friction by a belt 9 running on a driving pulley 10, an idler pulley 11 and two opposing rollers 12, 13 which serve to keep the belt 9 under tension and frictionally engaged with the pulley 7 over a circumferential arc. The driving pulley 10 is constantly rotated by an electric motor not shown in the drawing. A type disc 14 is mounted fast and coaxial with the pulley 7, on spindle 8, and is locked thereto by means of a resilient stirrup or circlip 16 engaging in a groove 15.

The disc 14 (FIGS. 1 and 2) is made of elastically flexible material (for example steel) and has its peripheral rim portion subdivided into sector-like tongues or strips 17 which are alike and separated by radial slots 18 of constant width. A segment 19 of the peripheral rim portion is without said tongues 17 and its width is chosen so as to obtain a certain optical result, as will be made clear hereinafter.

Each tongue 17 carries a printing type 32 (FIGS. 2 and 3) belonging to a series or set of types distributed around a circumferential zone of the disc 14. If it is desired to have a larger number of printing types available, each tongue may carry a second printing type 33 belonging to a second series or set of types distributed around a second circumferential zone of the disc 14. In this second case, the disc must be connected to a suitable positioning system 64 indicated diagrammatically in FIGS. 2 and 3, which is adapted to shift the disc 14 perpendicularly to the writing line for choosing a printing type belonging to one or the other series available on the disc 14.

Pivoted on a pin 21 fixed to the carriage 3 is a hammer 20 normally bearing against a stop pin 23 owing to the action of a return spring 22 anchored to the carriage. The arm of the hammer 20 has a certain elastic flexibility. The stop pin 23 is carried by a bail 24 which is also fulcrumed on the pin 21. The bail 24 is normally held so that it bears against a stop (not shown in FIG. 1) fast with the carriage 3 owing to the effect of a return spring 25 anchored to the carriage. Fixed to the bail 24 is the armature 26 of an electromagnet 27 supported by the carriage 3 and controlled in the manner which will be described hereinafter.

The operative end 28 of the hammer 20 carries an articulated head 29 mounted on a pin 30 and held in the normal state by a return spring 31 anchored to the arm of the hammer 20.

When the electromagnet 27 attracts the armature 26, the bail 24 pivots on the pin 21 and acts on the hammer 20 by means of the pin 23, carrying the hammer along in rapid rotation about the pin 21 until the rod 20 strikes against a stop element 62, after which the end 28 of the hammer continues its movement owing to the effect of the elastic bending of the rod 20 and the hammer goes on to strike a tongue 17 of the type disc 14. Under the effect of the blow of the hammer, the tongue 17 bends with respect to the disc 14 and strikes the printing sheet 2 arranged on the platen 1, imprinting the character thereon. A suitable ribbon inking system not shown in the drawing co-operates in the printing of the characters on the sheet 2.

The sectors of the type disc are also flexible in the plane of the disc itself, i.e. in the circumferential direction, so that each tongue 17, which after being struck by the hammer 20 has an oblique movement with respect to the printing sheet 2 due to the effect of the compounding of the rotary and bending movements, can be checked or braked in its peripheral speed of rotation at the instant of impact of the type with the printing sheet in such manner as to render the dragging of the printing type with respect to the sheet very slight.

The articulated head 29 of the hammer 20 avoids fouling occurring in the course of the printing operation between the tongues 17 of the constantly rotating type disc and the hammer itself when the striking of the hammer is not properly timed and the time for the striking of said hammer on the tongue and the rebound of the hammer is not well adjusted so as to be within and less than the time taken by the type disc to perform a rotation equal to the angle occupied by a tongue 17. The articulation of the head 29 prevents damage to the tongues of the disc 14 and intervenes in the cases of malfunction which have just been mentioned by means of the rotation of the head 29 under the action of impact with the side of a tongue and reduces the effect to a mere rubbing of the head 29 on the tongue following the strike by the hammer.

As has already been said, the transverse advance of the carriage 3 takes place by means of the system consisting of the screw 6 and the nut screw 34. The advance is of the step-by-step type, each step being equal to the distance between two successive columns of writing, and is controlled by a system comprising a ratchet wheel 35 fast with the screw 6 and controlled by a pawl 36, a driven gear wheel 37 coaxial with the ratchet wheel 35 and connected to it by friction under the action of a pressure spring 38, and a driving gear wheel 39 meshing with the driven gear 37 and rotated continuously by an electric motor not shown in the drawing. This motor may be the same motor that produces the rotation of the pulley 10.

The pawl 36 is pivoted on a pin 40 and is held in the normal position for locking the ratchet wheel 35 by the action of a spring 41 connected to a fixed point of the frame of the machine. The pawl 36 carries an armature 42 which can be attracted by an electromagnet 43 fixed to the frame of the machine when it is energized in the manner described hereinafter.

When the armature 42 is attracted, the ratchet wheel 35 can couple itself freely to the gear 37 by friction and the screw 6 is therefore caused to rotate, thus producing an advance of the nut screw 34 and of the carriage 3 fast with it. So that the advance may take place by successive steps corresponding to the successive columns of writing, the rotation of the ratchet wheel 35 by an angle equal to a tooth is such as to permit the transverse advance of the carriage 3 by a column of writing, for which reason the armature 42 must be controlled by the electromagnet 43 so that the pawl 36 releases the ratchet wheel 35 only for the time necessary for a rotation equal to one tooth; that is, the pawl 36, by disengaging itself from one tooth, will release the ratchet wheel 36, thereafter to lock it by immediately engaging the following tooth.

A return spring not shown in the drawing enables the carriage 3 to be returned to the starting position at the end of each line of writing or when a command for return to the beginning is supplied.

The system enabling the position of the type disc 14 to be controlled so as to obtain the printing of the selected character will now be briefly described.

The selection of the type for printing can be effected by means of a known optical system which employs a light source and photosensitive means which co-operate with a timing disc; the latter has a reference notch and a series of notches each corresponding to a different angular position of the types. The data received as input, for example from a keyboard, from a perforated tape or a magnetic recording tape, from the store of a computer, actuate the printing hammer when a given type is in the printing position.

More particularly, in this embodiment of the invention, the type disc 14 is used as the timing disc and as notches there are employed the radial slots 18 which separate the sector-like tongues 17. The reference notch is constituted by the sector 19 without any tongues, which has a radial depth greater than the ring of tongues 17, as can be seen from FIGS. 1, 2 and 3. A light source 44 sends a light beam which is picked up through the apertures in the disc 14 by two photoelectric cells 45, 46. The photoelectric cell 45 picks up the light beam transmitted by the source 44 through the slots 18 and the aperture 19, while the photoelectric cell 46 receives only the light beam transmitted through the aperture 19.

The photoelectric cell 45 is connected to a counter 50 which advances by one step at each light pulse received by the photoelectric cell 45 through the apertures in the disc 14. The counter 50 counts cyclically in synchronism with the rotation of the disc 14, in other words it advances by one step at each rotation of the disc 14 equal to the angle of a sector 17 and returns to the initial configuration after a complete revolution of said disc, so that to each configuration of the counter there corresponds a well-defined type on the disc 14. The zero position of the disc 14, and correspondingly of the counter 50, is identified by the passage of the aperture 19 in front of the light source 44. In this condition, in order to obtain reliable zeroizing of the counter 50, the photoelectric cell 46 is also energized (as explained hereinbefore) and causes a zeroizing pulse to be transmitted to the counter 50. Moreover, the counter 50 operates so that each configuration assumed by it represents the type carried by the tongue 17 which is currently in the position suitable for printing, that is in correspondence with the head 29 of the hammer 20. A suitable comparison device 52 provides for comparing the representation in code of the character to be printed supplied at the input with the configuration of the computer 50, producing in the case of coincidence a pulse which energizes the electromagnet 27 and thereby causing the action of the hammer 20 on the disc 14 in correspondence with the character to be printed. The light pulse produced at the photoelectric cell 46 by the passage of the aperture 19 in front of the source 44 also causes the energization of the electromagnet 43 and, therefore, the raising of the pawl 36 for a time sufficient for the ratchet wheel 35 to perform a rotation equal to one tooth, so that the carriage 3 advances by one printing step in the manner which has been described hereinbefore.

This printing device according to the invention can therefore operate continuously, printing a character for each revolution of the type disc and advancing by one printing step at the end of each revolution of the disc. It is clear that the device described will permit printing only if there is present a character supplied as input to the device and the transverse advance of the carriage can be arranged to occur only when there is a following character to be printed.

It will be observed that the electromagnet 43 is controlled by pulses generated by the rotation of the type disc 14, which therefore also performs the function of command of the transverse advance. It will moreover be observed that the aperture 19 in the disc 14 also performs another function, inasmuch as by stroboscopic effect it produces for the observer the persistence of an optical window or gate in correspondence with the head 29 of the hammer, thus permitting immediate reading of the characters printed.

FIG. 4 shows a modified embodiment of the printing device according to the invention. The purpose of this second constructional form is to increase the strength of the tongues 17 of the type-bearing element, reduce the peripheral speed of the types carried by the element and permit easier selection of the various series of types distributed over different circumferential zones.

To this end, the type-bearing disc is strongly dished to the form of a bell 47 the lateral surface of which is subdivided into tongues 48 disposed generally parallel to the axis of the disc and separated by slots 49. Two or more series of types 50, 51 may be disposed on different circumferential zones, so that each tongue 48 carries a type of each series. This bell shape of the type-bearing element makes it possible to obtain, for an equal number and given peripheral width of the tongue sectors, tongues which are less tapered and with a wider zone of attachment 52 than in the embodiment with the plane disc which is shown in FIGS. 1 and 2; this structure therefore becomes more robust as a whole. Moreover, with the bell shape of the type-bearing element, for an equal number and peripheral width of the tongue sectors and for an equal speed of rotation of the type-bearing element, the peripheral speed of the types becomes lower and, therefore, the dragging of the types on the printing sheet which is the cause of blurring of the print is further reduced.

Finally, with the bell shape of the type-bearing element, it is possible to obtain easy positioning of said element in correspondence with the selection of the types of one or the other series, as described hereinafter.

The bell 47 is mounted removably on a shaft 54 which has a pulley 55 keyed thereto. The shaft 54 is slidable in but rotates as one with the pulley 55 owing to the effect of a key 56 engaging in a groove 60. The pulley 55 lies in a fixed plane and is set in motion by a belt 57 which is kept tensioned against an arc of the pulley by two opposing rollers 58 and 59.

The shaft 54 can thus slide axially under the action of a positioning electromagnet 61 which permits the selection of the types of the series 50 or the series 51. The notch of a sector 53 of the bell 47 enables the same stroboscopic effects to be obtained as with the aperture 19 in the disc of FIG. 1 for observation of the characters printed.

Fig. 4 does not show the other conventional parts forming part of the printing device for reasons of simplicity and clarity and because they can easily be adapted from the embodiment illustrated in FIG. 1.

It is to be noted that in both the embodiments illustrated in FIGS. 1 and 4 the type-bearing disc is mounted removably on the carriage and can therefore be exchanged for other type-bearing discs so as to permit different kinds of printing. Moreover, an important advantage of the invention is that the interchangeable type-bearing elements make it possible for the printing device to operate when the feed is effected by means of different input codes, inasmuch as it will be sufficient to choose the distribution of the types on the tongues of the carrying member in such manner that it is in relation to the selected input code. In other words, since there corresponds to each configuration of the counter mentioned before a well-defined type on the type-bearing element, to be precise that which is in the position suitable for being struck at the instant of the configuration, and as the same configuration of the counter represents different types according to the code to which reference is made, in order to obtain a type-bearing element which can function with a given code it will be sufficient to distribute the types thereon in such manner that, once the element has been mounted on the printing device, there corresponds to each configuration assumed by the counter during the rotation of the type-bearing element, in the striking position, that type which is represented by the said configuration in the code selected.

Although only a single type disc has been described in relation to each embodiment, it is clear therefore, that a series of interchangeable discs will be provided. In general such discs will all carry some corresponding types, as well as types individual to certain discs only, and on some discs types will be positioned differently from the corresponding types on other discs in accordance with different input codes with which the discs are intended for use.

Various modifications of, and alternatives to, the embodiments described are naturally possible. For example, the arrangement of the printing sheet with respect to the type-bearing element and the hammer may be changed and the step-by-step transverse advance system may be modified by keeping the type-bearing element in a fixed position and translating the platen with the relevant printing sheet instead.

Claims

I claim:

1. A printing system adapted for printing characters of any particular language in response to coded input information from a selected one of a plurality of input units wherein said input units utilize different coded signals to represent the same character to be printed, comprising:

rotatable disc support means for carrying a single mounted disc;

a character carrying disc dished to the form of a bell removably mounted on said rotatable support, said disc adapted to carry characters corresponding to input information from one of said plurality of input units, said disc comprising elastically flexible material and including a plurality of equal sectors, each of the sectors of the disc being substantially L-shaped, each of said sectors carrying one of said characters disposed in a circumferential zone of the disc, said characters being located on the outer surface of the bell adjacent the disc's circumferential periphery,

paper support means disposed adjacent to said mounted disc and said rotatable disc support means, said support means being movable relative to said paper support means to provide for serial printing from the disc along a line on a paper supported by said support means;

an actuable hammer adjacent said mounted disc when the sector is at a given angular position, the hammer striking the inner surface of the disc;

means for rotating said mounted disc to move each of said plurality of sectors of the disc seriatim through said given angular position; and,

control means for providing a coded indication of the particular circumferentially located sector which is passing through said given angular position, said control means including a reference point on said disc and means for detecting said reference point, said coded indication being compared with said coded input information from said selected one of said input units so that correspondence between said indication and said information causes said hammer to be activated to print one of said characters, the character being printed being determined by the disc mounted on said support.

2. A printing system adapted for printing characters of any particular language in response to coded input information from a selected one of a plurality of input units wherein said input units utilize different coded signals to represent the same character to be printed, comprising:

rotatable disc support means for carrying a single mounted disc;

a character carrying disc removably mounted on said rotatable support, said disc adapted to carry characters corresponding to input information from one of said plurality of input units, said disc comprising elastically flexible material and including a plurality of equal sectors, each of said sectors carrying one of said characters disposed in a circumferential zone of the disc,

paper support means disposed adjacent to said mounted disc and said rotatable disc support means, said support means being movable relative to said paper support means to provide for serial printing from the disc along a line on a paper supported by said support means;

an actuable hammer adjacent said mounted disc for striking a sector of said plurality of sectors of said mounted disc when the sector is at a given angular position, said hammer including an arm, an articulated head mounted on said arm substantially perpendicular thereto, and release means for releasing said head from a rigid position, said means for releasing being adapted to cooperate with the edges of said sectors to be activated when the head of said hammer, striking between adjacent sectors, strikes the edge of one of said adjacent sectors, said means for releasing being inoperative when said hammer head strikes a single sector, said means for releasing including a return spring connecting said head and said arm for biasing said head to an unreleased position;

means for rotating said mounted disc to move each of said plurality of sectors of the disc seriatim through said given angular position; and,

control means for providing a coded indication of the particular circumferentially located sector which is passing through said given angular position, said control means including a reference point on said disc and means for detecting said reference point, said coded indication being compared with said coded input information from said selected one of said input units so that correspondence between said indication and said information causes said hammer to be activated to print one of said characters, the character being printed being determined by the disc mounted on said support.

3. A printing device comprising:

a rotatable disc support mounted on a transversely movable carriage;

a type carrying disc mounted on said rotatable support, said disc comprising elastically flexible material and including a plurality of equal circumferentially located sectors, each sector carrying a type disposed in a circumferential zone of the disc, said disc being removably mounted on the support and selectively interchangeable with other type discs;

paper support means disposed adjacent said disc, said rotatable disc support and said support means being relatively movable to provide for serial printing from the disc along a line on a paper supported by said support means;

a hammer adjacent the disc and actuable for striking a sector of said plurality of sectors of the disc at a given angular position of the disc;

means for rotating the disc to move each of said plurality of sectors seriatim through said angular position;

indicating means for providing signals indicative of the sector of said plurality of sectors occupying said angular position of the disc for comparison with input code signals to determine the proper instant for operation of the hammer;

a continuously rotating motor for advancing said carriage step-by-step past a printing station;

a friction clutch coupling said motor to said carriage;

ratchet means for arresting successive portions of said carriage in said printing station;

an electromagnetic device cooperating with said ratchet means and energizable to permit a one-step movement of said carriage; and,

control means for generating a command signal to energize said electromagnet, said control means including a reference gap on said disc and a photoelectric means for generating said command signal upon detecting said gap during rotation of said disc.

4. A printing device comprising:

a rotatable disc support;

a type carrying disc mounted on said rotatable support, said disc comprising elastically flexible material and including a plurality of equal circumferentially located sectors, each sector carrying a type disposed in a circumferential zone of the disc, each of said sectors being identified by a code signal, said disc being removably mounted on the support and selectively interchangeable with other type discs;

paper support means disposed adjacent said disc, said rotatable disc support and said support means being relatively movable to provide for serial printing from the disc along a line on a paper supported by said support means;

a hammer adjacent the disc and actuable for striking a sector of said plurality of sectors of the disc at a given angular position of the disc;

means for rotating the disc to move each of said plurality of sectors seriatim through said angular position;

indicating means including:

a plurality of equal reference slots on said disc, each of said slots being defined by two contiguous sectors of said plurality of sectors,

a reference gap on said disc, said gap being wider than each slot of said plurality of slots,

a photoelectric system including means for generating a counting pulse upon detecting one of said slots and a start command upon detecting said reference gap during rotation of said disc,

and counter means for representing cyclically the code signals identifying the successive sectors of said plurality, said counter being responsive to said start command to represent the sector next passing through said given angular position after said gap and being further responsive to each counting pulse to represent each of the following sectors; and

control means for comparing the code signal indicative of the particular sector of said plurality of sectors which is passing through said given angular position of the disc with an input code signal to determine the proper instant for operation of the hammer.