US3904013A - Writing machines with fluid drive means - Google Patents

Abstract

A writing machine of the kind in which successive writing of characters side by side and line by line is effected on a record carrier led over a platen by means of character carrying type bars arranged side by side on an arcuate pivot axis and adapted, when actuated, to pivot to effect recording at a common recording point, is such that there is provided in common for a plurality of type bars, a fluid drive for producing pivoting movement of a selected type bar, fluid driven drive elements, one for each type bar, a fluid control in the region of each fluid drive element for connecting the fluid drive to the fluid driven element appropriate to a selected type bar and a selector moveable into one of a number of predetermined positions in accordance with the type bar to be selected. The selector is arranged, when moved to such a position, to bring about the coupling of the fluid drive to the fluid driven drive element of the selected type bar by operation of the fluid control in the region of that element.

Description

United States Patent Rummel 1 1 WRITING MACHINES WITH FLUID DRIVE MEANS [75| Inventor: Hermann RummeLDoerentrup,

Germany [73I Assignce; Nixdorf Computer AG, Paderborn,

Germany [22] Filed: Apr. 26, 1973 [21] Appl. No: 354,705

[311] Foreign Application Priority Data May 4, 1972 Germany 2221871 [521 11.5. C1. 197/15; 1()1/93.1; 235/91 F [51] Int. Cl r. B4lj 23/20 158] Field of Search 197/15, 19, 20, 1 R; 101/93 C, 93.1; 235/91 F; 178/29 [561 References Cited UNITED STATES PATENTS 897,959 9/1908 Cahill 197/15 1118916119 3/1914 Burbou 197/15 1,904,631 4/1933 Swanson 197/15 X 1937,98 12/1933 Rugh r r r .r 197/15 X 2.118.113 10/1941) Klcinschmidt, 178/29 2.979255 4/1961 Hubl 101/936 X 3,319,165 11/1965 Greene ct a1, 197/15 X 3 3=12 297 9/1967 Greene 197/15 X FOREIGN PATENTS OR APPLICATIONS 321144 9/1924 United Kingdom 197/15 1 1 Sept. 9, 1975 Germany r 197/15 Germany 197/15 Sheridan [57} ABSTRACT A writing machine of the kind in which successive writing of characters side by side and line by line is effected on a record carrier led over a platen by means of character carrying type bars arranged side by side on an arcuate pivot axis and adapted, when actuated, to pivot to effect recording at a common recording point, is such that there is provided in common for a plurality of type bars, a fluid drive for producing pivoting movement of a selected type bar, fluid driven drive elements, one For each type bar, a fluid control in the region of each fluid drive element for connecting the fluid drive to the fluid driven element appropriate to a selected type bar and a selector moveable into one of a number of predetermined positions in ac cordance with the type bar to be selected The selector is arranged, when moved to such a position, to bring about the coupling of the fluid drive to the fluid driven drive element of the selected type bar by open ation of the fluid control in the region of that element 28 Claims, 14 Drawing Figures PATENTED $5? 91975 3. 904. 013

PATENTED'SEP ems SHEET 6 [1F 7 WRITING MACHINES WITH FLUID DRIVE MEANS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to writing machines and more specifically to writing machines of the kind adapted to write characters successively and in successive lines on a record carrier which is fitted over a platen, the characters being written by type carried on type bars which are arranged side by side and pivoted at points lying in an arcuate line, each bar, when actuated, moving the character carried thereby to a predetermined common striking point.

ll. Description of the Prior Art The best known example of a writing machine of this kind is the ordinary typewriter, in which there is an arrangement of type bars on an arc of a circle which is so oriented with respect to the platen that the type bars, which may be either mechanically or electrically operated, are moved, when operated, to cause the type carrying ends thereof to strike the platen at the correct place. The mechanism required for operating the type bars is expensive and, in practice, has to be arranged so that the type bars. which are pivoted, may be operated with minimum efi'ort but nevertheless with precision and also with maximum speed. In writing machines with the type bars mounted in the same way, they have a single, common point of impingement on the platen, so that for all type bars and type characters the writing process is the same.

Developments in the field of data processing have produced a requirement for writing machines capable of very high writing speeds (i.e. speeds in terms of numbers of characters printed in a unit of time) combined with optimum writing accuracy and high operational reliability. Normal writing machines, such as typewriters are capable of writing speeds of up to about 20 to 24 strikes a second. Other writing mechanisms, operating with so-called golf ball heads are capable of writing speeds of about 20 strikes a second. If writing speeds above such values are to be attained by writing machines using type bars, it is necessary to reduce the mass of the moving elements, more particularly that of the type bars, and to use shorter type bars. In this way it is possible to achieve writing speeds of about 30 to 35 strikes a second. However, for satisfactory and reliable mechanical operation, the type bars must be strong enough to ensure that they will not be bent during the writing process or during their movement, or as a result of the action of the means used for driving them. In addition, where, as is the normal case, the type bars have bent type heads, there is a liability to the occurrence of undesired rolling movement because the center of gravity lies outside the pivoting plane passing through the point of mounting and the length of the bars. For this reason, too, the mass of the type bar cannot be reduced below a minimum value which puts an undesirably low limit to the attainable writing speed.

Known writing machines using type bars have to have a complex driving mechanism for each type bar. During the outward movement, i.e. movement from the rest position, each type bar drive must first of all overcome a restoring force which returns the type bar to its rest position after each strike. It is moreover desirable for each type bar to have positive acceleration when striking. However, because, in known machines with type bars, the driving impulse for a type bar ceases after about half the outward movement, only the kinetic energy which it has then attained is available to carry it on to the striking position and effect a printing strike and a substantial proportion of this energy is used up in increasingly tensioning the restoring spring. In addition, it is very difficult to achieve a lever ratio (mechanical advantage) for each type bar that will result in satisfactory writing in the shortest possible time and require a minimum amount of energy. The type bar driving mechanisms occupy so much space as to result in known writing machines being of such size as to make it necessary, practically speaking, for the type bars to be arranged on only a segment of an arc of a circle in front of the platen. Although it is known to arrange the type bars round a full circle lying either in front of or underneath the platen, this leads to a writing machine that is disproportionately large and moreover, is such that the driving mechanism obscures a view of the writing. Furthermore, with such an arrangement used in conjunction with a keyboard, the machine is necessarily far from compact. This is because in a type bar machine with mechanical drive to the type bars from a keyboard, the drive mechanisms are all oriented in the same direction, whereas the driven parts of the type bars must point in different directions because of the radial arrangement. In general, the driving and driven directions coincide only for the central type bar. F or all other type bars the difference in angle increases with the angle between the respective type bar and the central type bar the outermost type bars having the greatest difference between driving and driven directions. If the angle embraced by the segment in which the type bars (when at rest) lie, is more than and especially if it approaches 360 (i.e. approaches a full circle) it is practically impossible to obtain a clearly visible mechanically driven typing action in typewriters with constructions as used today.

Further requirements that a writing machine should fulfil concern the guiding of the record carrier on the platen. It is necessary to introduce the record carrier on to the platen, to lead it away from same and at the same time to be able to observe the writing process without hindrance. Record carriers used in data processing include not only ordinary sheets of paper but also, for example, invoice cards and other stiff record carriers which do not withstand bending over sharply.

It is thus necessary in known machines to make a variety of compromises in achieving high-speed writing machines and these compromises result, owing to limitations of the extent to which individual parts can be reduced in size and mass, in severe restriction of the writing speeds attainable. The present invention seeks to overcome these difficulties and, as will be seen later, does so by making it possible to use unusually short type bars arranged around a full circle immediately in front of the platen at the same time providing, for driving the type bars, a driving arrangement that does not involve expensive mechanisms comprising numerous mechanically moving elements between the type bars and a keyboard.

SUMMARY OF THE PRESENT INVENTION According to the present invention, there is provided a writing machine of the kind in which successive writing of characters side by side and line by line is effected on a record carrier led over a platen by means of a plurality of character carrying type bars arranged side by side on an arcuate pivot axis and adapted, when actuated, to pivot to effect recording at a common recording point, there is provided in common for a plurality of type bars, a fluid drive for producing pivoting move ment of a selected type bar, a plurality of fluid driven drive elements, one for each type bar, fluid control means in the region of each fluid drive element for connecting the fluid drive to the fluid driven element appropriate to a selected type bar and selector means moveable into one or other of a plurality of predetermined positions in accordance with the type bar to be selected, said last-mentioned means being arranged, when moved to such a position, to bring about the coupling of the fluid drive to the fluid driven drive element of the selected type bar by operation of the fluid control means in the region of that element.

The underlying idea of the invention lies in the realisation that if the type bars used for effecting writing are reduced in mass. less force is needed to cause them to pivot without loss of speed of the impelled bars and that it is perfectly practical to construct a fluid drive (this expression fluid drive" as herein used includes both pneumatic and hydraulic drives though, as will be apparent later, pneumatic drive is preferred) arrangement which, though small, is capable of providing forces which are entirely adequate for moving type bars of reduced weight at adequate speeds and fluid drive systems in accordance with this invention can be readily designed to produce the required forces and speeds such that adequate kinetic energy of the type bars for effecting writing is available. In addition there is design freedom to arrange a fluid drive system wherever desirable (in relation to the actual writing mechanism) remotely, if desired because the only necessary connections with the writing mechanism are pres sure or suction lines assigned to all type bars in common. The writing mechanism itself requires merely fluid operated drive elements so that pressure or vacuum acting on them causes them to move. By coupling fluid actuated drive elements by simple mechanical connections with the respective type bars, rapid and precisely controlled writing movement of the type bars can be achieved. The position of the type bars relative to the fluid control and fluid driven drive elements is immaterial, because no lever transmissions or articulated joints are needed therefor and there are no relatively large masses to be moved and which need to occupy given positions. Also, there is no need for strong restoring forces which have to be overcome. This is in sharp distinction to the usual known writing machines in which restoring forces are generated by the use of relatively strong springs. A further important advantage is that no difficulties or disadvantages arise, as happens in the case of known writing machines, be cause of changes in the direction of movement between the keys of a keyboard and a type bar driven by that key.

The fluid drive may be and preferably is an impulse fluid drive with pressure or vacuum impulses at a frequency which can be chosen equal to the speed of writing or to an integral multiple thereof. The provision of such an impulse drive makes it possible to realise a particularly simple control for operating a respective type bar. All that is needed in the fluid drive for this purpose is, for example, actuation of a valve by means of which the pressure or vacuum impulses can be transmitted direct to the fluid control in a selective manner. If these impulses have a frequency equal to the prescribed speed of writing or to an integral multiple thereof, then the exact point in time at which the valve opens is immaterial; all that matters is that a complete pressure or vacuum impulse can act. Naturally, this is especially reliable and satisfactory in the case in which the frequency of the pressure or vacuum impulses is an integral multiple of the speed of writing.

The pressure or vacuum impulses can be generated by simple pumping means. There may be one such pumping means assigned to all the type bars or there may be more than one, each being assigned to a group of type bars. Such pumping devices may be provided either singly and generate the pressure impulses and the vacuum impulses inside a working chamber or it is possible, alternatively, to provide two pumping devices which are displaced in phase, preferably working in phase opposition. The mechanical drive to such pumping means can be effected in a simple manner by rotary eccentric drives. By regulating the speed of rotation the impulse frequency can be adjusted to accord with different writing speeds. With an electrically or automatically actuated writing machine it is possible to adjust the aforesaid speed of rotation to give writing speeds of the order of strikes a second. This is because a fluid drive making only small movements has very little inertia indeed. Moreover, there are no undesirable dead" forces like those due to restoring springs, to be overcome.

instead of providing a pump or pumps a pulsed fluid drive can be obtained from a constant pressure source, such as an air line, by means of a rotary valve arrangement, eg one including a rotary sleeve having peripheral grooves and driven continuously by a rotating shaft the peripheral grooves providing desired connections at the desired times and for the desired periods between the pressure source and fluid control channels, the grooves covering and uncovering passages in a guide block for the rotary sleeve. Such an arrangement may be extremely reliable and simple. if the grooves are so arranged that they connect with a line of constant pressure at regular intervals of time during the rotation of the rotary sleeve they can serve to transmit the pressure into the fluid operated writing mechanism, a pulse-like interruption of the transmission being provided by the movement and the limited length of the peripheral grooves. It is possible in this way to generate pressure impulses whose sequence is independent of pumping speed. The impulses can be led to the drive elements for the type bars from two different directions, so that some act as though they were vacuum impulses because they act in a direction opposite to that of the others.

Alternatively, of course, pressure impulses could be obtained by means of linearly movable elements, e.g. slide valves or electromagnetic valves actuated at a given frequency.

As already stated the fluid drive used in carrying out the invention could be hydraulic or pneumatic or it may use both principles. This is obvious because any drive effect produced by a pneumatic drive could be produced by a hydraulic drive or vice-versa. A point to consider is that the incompressibility of the hydraulic liquid in a hydraulic drive may be advantageous as regards the attainment of high speeds of writing. Admittedly, problems of sealing arise, and the handling of liquids presents problems of a practical nature as compared with the handling of air. Another advantage of a pneumatic drive is that the specific gravity of air is negligibly small by comparison with that of a suitable liquid. As a result, the intrinsic forces required at the beginning of an impulse in a pneumatic drive medium are considerably smaller than in a hydraulic drive medium, because the small mass necessitates a correspondingly smaller force to achieve a given acceleration. As stated any fluid drive may be used but, for simplicity and shortness of description, pneumatic drives (which are preferred) will be assumed throughout in what follows.

ln a further advantageous development of the invention there is provided at least one pressure chamber which is concentric with the arcuate pivot axis of the type bars and is continuously connected with the drive and its volume is limited by a number of selector slide valves equal in number to the number of type bars present. The slide valves are arranged to be moved by releasing them by means of selector devices into positions in which they open communication between the pressure chamber and the respective drive element.

This further development of the invention makes possible a particularly compact writing machine. Where the type bars are arranged on a circle or, for example, on two semi-circular segments, they may have assigned to them a special drive segment provided with ducts for carrying the pressure medium, these ducts containing drive elements for the type bars. Where the type bars themselves are arranged on an arcuate pivot axis those ducts which lead the pressure impulses to the drive elements of the type bars may advantageously be arranged to emanate radially from the pressure chamber and extend in the radial direction. The provision of a continuous pressure chamber concentric with the pivot axis allows the pulsating pressure action of the drive means to be led to this pressure chamber in a particularly simple manner at a desired point of an overall writing segment with several type bars. The side channels potentially leading to respectively one drive element for respectively one type bar can then branch off from the arcuate pressure chamber. Such a drive element may be, for example, a piston inside a working cylinder, said piston causing the type bar to which it is assigned to pivot. If now the selector device is so arranged that only one of these branches for a drive element of a type bar is opened, then this is enough to ensure the complete outward movement of the type bar. As the number of selector slide valves provided equals the number of type bars present, there being one portion seated in a respective valve-like bore which, in certain positions of the selector slide valves, is connected with the working space of the type bar drive elements, the sole control operation consists in the release of the selector slide valve of the respectively selected type bar by the selector devices. This enables the slide valve in question to be moved by pressure acting on it when a pressure impulse arises in the pressure chamber until the channel from the arcuate pressure chamber is in communication with the working space for the drive element of the selected type bar.

In another development of the invention two concentric pressure chambers are provided, of which one is continuously connected with second drive elements for the type bars and, when pressure acts, produces a movement of the type bar (which it is assumed has just been pivoted away from its rest position) back into that position. In this way it is possible to produce the return movement of the type bars as well as their outward movement by means of pressure impulses. A double ended lever, for example, may be provided. Outward drive of a type ,bar is provided by one end of the lever as a result of pressure in the first pressure chamber, while the second lever arm is acted on as a result of pressure in the second pressure chamber. Thus no suction effect is required to return type bars into their rest positions and a somewhat more uniform mode of working of the writing mechanism is achieved.

Where the pressure is generated in pulses it is necessary to equalise the pressure between the working chambers of the drive elements and atmosphere during the intervals elapsing between individual pressure pulses. For this purpose a connection of a concentric pressure chamber with atmosphere can advantageously be made via the drive. This connection can, for example, be effected by control slide valves which are coupled with the drive shaft and which, in given positions of said shaft open a connection between the concentric pressure chamber and atmosphere. This is particularly advantageous where two pumping devices working in phase opposition are provided. The common drive shaft for these pumping devices then drives the two control slide valves, so that these work positively at a speed corresponding with the opposed phase operation and, for example, each may, in one extreme position connect one pumping device with atmosphere. Where the drive is effected by a rotary sleeve with peripheral grooves the connection of the pressure chamber with atmosphere can be run via the rotary element. For this purpose the element is suitably constructed as a sleeve rotatably arranged on a cylindrical pin or rod, with a connection provided between a peripheral groove and the space between the sleeve and the rod or pin. if this space communicates with atmosphere, as is easily arranged, then this will provide the required connection between the pressure chambers and atmosphere in given positions of the drive.

The choice between returning a type bar into its rest position either by suction or by pressure action leads to a choice between two different principles of working. When only one pumping device utilising pressure and vacuum is used, the excess pressure that arises in the pressure chamber when the type bar reaches the writing position is equalised with atmosphere by arranging the respective drive element to open a bore leading to atmosphere. Subsequently, reduced pressure is generated in the working space of the drive element. When the type bar has performed only a small part of its return path the drive element causes the bore leading to atmosphere to be reclosed, and the reduced pressure acts on the type bar via the drive element. Once the reduced pressure has reached a certain value it overcomes the retaining force with which the selector slide valve is held in its selected position. If the type bar has not yet reached its rest position and if the drive element still exerts a compressing action, the pressure is allowed to escape to atmosphere, for which purpose a connection between the working space and atmosphere is provided on the selector slide valve close to its rest position. In the corresponding working position of the drive that is then reached, the vacuum can equalise with the outside pressure via a connection passing through the drive. In this case a single chamber thus acts alternately as a pressure and as a vacuum chamber.

Where use is made of two pumping devices working in opposite phase or a source of constant pressure controlled by valve means to provide pulses the pressure chamber is connected to atmosphere via the drive in its vacuum position. This is because the vacuum position of the drive is that position in which the respectively actuated drive element for a type bar has been restored into its rest position. Irrespectively of whether this ensues by the action of pressure or vacuum, the normal pressure relationships must be re-established before the next work cycle takes place in order to ensure a satisfactory utilisation of the working capacity of the pneumatic drive. By arranging the rotary element for the drive to open a channel when in the vacuum position, pressure equalisation between the pressure chambers and atmosphere can be ensured in a very simple manner.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in and further explained in connection with the accompanying drawings, in which:

FIG. 1 illustrates one form of writing mechanism in accordance with the invention and having a pneumatic drive provided by a simple single acting diaphragm p ps FIG. 2 is a composite view of the writing mechanism of FIG. 1 looking in the direction of the arrows II, III and IV of FIG. 1,

FIG. 3 is a graphical figure showing pressure distribution and amplitude of motion in the pneumatic drive of FIG. 1 during a given portion of the operation,

FIG. 4 shows graphically the pressure distribution of the working volume of the writing mechanism of FIG. 1, during the given portion of .the operation,

FIG. 5 shows another form of a writing mechanism in accordance with the invention with a pneumatic drive provided by two diaphragm pumps working in opposite phases,

FIG. 6 shows a further form of writing mechanism in accordance with the invention with a pneumatic drive to which a constant pressure is fed and which generates a displaced-phase pressure effect,

FIG. 7 is another view of the pneumatic drive of FIG. 6 taken on the elevation VII-VII of FIG. 6,

FIG. 8 is a representation of a control element in the pneumatic drive shown in FIG. 7,

FIGS. 9 to 12 are sectional views taken on the lines IX, X. XI and XII of FIG. 8 of the control element of FIG. 8,

FIG. 13 is an explanatory working diagram of a writing mechanism as illustrated by FIG. 6, and,

FIG. 14 is an overall view of a writing machine in accordance with the invention.

DETAILED DESCRIPTION The figures illustrating writing mechanisms show in each case a type bar and its driving elements in side elevation. The elements common to all type bars, which in correspondence with the arrangement of all the type bars are in part constructed in the form of an arc of a circle, are therefore shown in section. These relationships are revealed by a comparison of the writing mechanisms with the overall view shown in FIG. I4.

FIGS. 1 and 2 show a type bar with associated pneumatic drive and pneumatic control in relation to a platen 24. There is a group of type bars arranged on an arc of a circle which is disposed in such a way that the pneumatic drive and the nature of the control common to all type bars can be seen. In addition, the type bar 10 with its associated movable drive elements can be seen. Individual parts which are unnecessary for an understanding of the invention, e.g. screwed joints, bearings and couplings are not illustrated in the figures.

The type bar 10 carries at its outer free end a type character 12. In the rest position it is held by an arcuate magnet strip 50 common to all the type bars. It is mounted on an arcuate bearing axis 16 shown in section in FIG. 1. When actuated the bar 10 pivots on the pivot axis 16 and swings its type character 12 along a circular path 20 to strike the platen 24. The arcuate bearing axis 16 is supported by a type bar segment 48 which has a guide slot for each type bar. Thus the type bar 10 can pivot inside the slot 18. At its pivot end on the bearing axis 16, the type bar 10 has gear teeth 14 engaging in corresponding teeth 28 on an intermediate bar lever 26. This intermediate bar lever 26 is pivoted on a further arcuate bearing axis 30 concentric with the axis 16 and has, diametrically opposite the teeth 28, further teeth 32 engaging teeth 34 on a drive lever bar 36 which is pivotably mounted on a further arcuate bearing axis 38. A slot 42 provided for each drive bar in a drive segment 54, permits pivotal movement of the drive lever bar 36. This movement is imparted by a piston 46 which is driven in manner to be described later. A buffer stop 22 made of elastic or hard resilient material is secured to the drive segment 54. The upper end of this stop is shaped as shown to prevent chattering of the type bar 10 directly on the platen 24 and ensures an interference-free return movement of the type bar 10 allowing striking of the platen 24.

An arcuate arrangement of selector bars is provided radially outside the type bar segment 48 and in front of the drive segment 54. The manner in which the pneumatic control for the type bars I0 is actuated will be later described but the selector bars work much in the same known way as the corresponding parts of a teleprinter for example. They are arranged in a surrounding ring, and can act on the control of every one of the type bars. Cut-away portions in the selector bars in accordance with a prescribed code ensure that each particular mutual positional combination, if set up, procures actuation of a selected type bar. The way in which the selected type bar is moved is yet to be described.

The pneumatic drive is provided underneath or outside the type bar segment 48 and the drive segment 54 and is secured to a bearing frame 86. The bearing frame 86 is optionally displaceably, and is mounted on bearing rods 90 and 94 by means of guides 92 and 96. The pneumatic drive is provided by a diaphragm pump with a pneumatic chamber 98 in which is a diaphragm 100 which is caused to vibrate from underneath by an eccentric rotary drive. It rhythmically compresses the air in the pneumatic chamber98 so that a pulse-like pneumatic driving force is generated for the type bars.

The following description gives the mode of functioning of the arrangement illustrated in FIGS. 1 and 2 and also describes further individual components. To begin with the generation of the pulsating driving force will be described together with its effect on the control and the drive of the type bars 10 in accordance with the settings of the selector bar arrangement 72.

The walls of the pneumatic chamber 98 are constituted by surfaces of the bearing frame 86, a frame 162 and a diaphragm plate 104 attached to the diaphragm. The said diaphragm 100 is clamped peripherally between the bearing frame 86 and the frame 102. it may consist, for example, of two air-impermeable material layers on whose top surface is a counterplate 101, the diaphragm 100 between itself between this plate 101 and the lower diaphragm structure rests with the periphery of the plate 104 on the lower edge of the frame 102. The diaphragm plate 104 is connected with the interior of a cylindrical guide sleeve 116 via a flexible airtight connection 114, which forms a duct 123. The guide sleeve 116 is secured to an eccentric bushing l 18 serving for the eccentric guiding of a square sectioned drive shaft 120. 1n addition, the diaphragm plate 104 is coupled directly to the guide sleeve 116 via rocker arm links 108, of which only one is shown in FIG. 1. In the position shown of the drive shaft 120 the pneumatic chamber 98 possesses its maximum volume and the air space above the diaphragm 100 is connected with atmosphere via a diaphragm bore 121, the duct 123, a duct 124 in the guide sleeve 116 and a bore 122 in the eccentric bushing 118. The rocker arms 108 are movably coupled to the diaphragm plate 104 with an extension via a pin 110. When the bushing 118 is turned by the drive shaft 120 an oscillatory movement of the diaphragm 100 ensues as a result of the rhythmic rise and fall via this coupling A pressure equalisation between the pneumatic system and the outside can alternatively take place via the flexible line 114 or the duct 123, in each case in the operational position shown in FIG. 1.

The pneumatic chamber 98 is connected with the type bar segment 48 via a pressure line 80. The pressure line 80 is secured in the type bar segment 48 and in the bearing frame 86 at both ends by means of screwed joints 82 and connecting elements 84 respectively. A duct 88 is provided in the bearing frame 86 and connects the connecting line 80 with the interior of the pneumatic chamber 98, so that during each upward movement of the diaphragm 100 an increase in pressure in the bore 60 of the type bar segment 48 is generated. This bore 60 is assumed to be common for all type bars, but, alternatively, there may be a number of such bores, each assigned to one respective group of type bars, so that each type bar is connected with the pneumatic drive by the shortest possible route.

When a pulse-like increase in pressure is generated in the bore 60 it arises also in a pressure chamber 58 via a transverse bore 52, which chamber runs in arcuate manner through the entire type bar segment 48 and is assigned to all type bars. An oscillating or pulse-like pneumatic pressure is therefore available in this pressure chamber 58. The frequency of the pulsing can be adjusted (by adjusting the speed of revolutions of the drive shaft 120) to correspond to a prescribed writing speed or an integral multiple of a prescribed writing speed.

Each type bar has a control assigned to it formed by channels provided in the driving segment 54 and each opened and closed by a selector slide valve 69 in a radial bore 62. In this way the already described pistons 46, which causes the drive lever bars 36 to pivot, are actuated.

The control process for actuating the type bar shown in FIG. 1 is initiated by bringing the arcuate selector rails of the arrangement 72 into a mutual position in which a flattened portion at the lower end of the selector slide valve 69 can fall through a gap formed by the cut-away portions of the selector bars. To carry out the adjustment movement the selector bars can be displaced mutually by an amount determined by their code around the entire arcuate arrangement of all type bars. For this purpose they are secured to the drive segment 54 by means of a bearing surface 78 or a bearing element 76 and several guide pins 74. When the selector rails are located in the position in which the flattened portion 70 shown can fall into a gap formed by their cut-away portions, then the selector slide valve 69 shown is moved downwards within the capture range of a magnetic strip 79, which then holds it. A branch bore 64 is now in communication with the pressure chamber 58 and the pulsating pneumatic pressure in said pressure chamber acts on the piston 46, which is in a widened bore extension 44 of the bore 64. The piston 46 accordingly moves towards the right from the rest position shown in FIG. 1. The portion 40 of the drive lever bar 36 is in the cut-away portion 47 of the piston 46 and accordingly the drive lever bar 36 is moved pivotally, swinging clockwise about the arcuate bearing axis 38. This movement causes a rotation of the intermediate lever bar 26 on its arcuate bearing axis 30 and the type bar 10 is caused to pivot about the arcuate bearing axis 16 so that the type character 12 swings to the platen 24 along the path 20. The impulse like control of the pneumatic pressure in the arcuate pressure chamber 58 and the initially acting retaining force of the magnetic strip 50 causes the type bar 10 to start its swing suddenly, so that, when it moves it does so fast and there is adequate kinetic energy to produce a good strike on the platen 24. As already mentioned the buffer stop 22 provides a springy stop for the type bar, preventing chattering of the character 12 on the platen 24 and initially return movement of the type bar 10.

The control of the final part of the movement of the type bar 10 ensues in the described manner to the point where the piston 46 during its outward movement, provides access to a bore 65 so that excess pressure present in the pneumatic system escapes to atmosphere through the bore 65. When this happens the driving force which previously acted directly on the piston 46, disappears. However, at this time, the type bar 10 still has kinetic energy so that it continues to move towards the platen 24 and strikes the buffer stop 22. The latter is so adjusted that the type character 12 can strike the platen 24 sharply, the spring action of the buffer stop 22 at once initiating the return movement of the type bar 10. As the intermediate lever bar 26, the drive lever bar 36 and the piston 46 are positively coupled with the type bar 10, these elements follow the movements of the said type bar 10, and the piston 46 is also moved back. The pneumatic drive, which now generates a suction effect, aids the return movement of the piston 46. In the meantime the diaphragm has been moved downwards by the further rotation of the drive shaft 120, so that the volume of the pneumatic chamber 98 now once more increases and a vacuum is formed in the space formed by the bore 60, the transverse bore 52 and the arcuate pressure chamber 58. This augments the return movement of the piston 46. During these events the selector slide valve 69 is still held in its lower position by the magnetic strip 79. The retaining force of the magnetic strip 79 is so chosen that the return of the selector slide valve 69 occurs suddenly and only when a certain vacuum is reached in the arcuate chamber 58. At this point in time, however, the type bar will already be close to the rest position (shown in FIG. 1 and within the capture range of the magnetic strip 50. During these events the piston 46 is once more moved to the left and air present in the bore 44 or in the bore 64 is released through a duct 66 to atmosphere in correspondence with its return movement if the selector slide valve 69 has meanwhile been moved back. This is made possible by providing a reduced diameter portion 68 on the selector slide valve 69. In this way the arrangement once more assumes the rest position shown in FIG. 1, in which a pressure equalisation between the pressure chamber 58 and atmosphere occurs via the diaphragm bore 121, the flexible duct 123 and the mutually opposite bores 124 and 122 of the rotary drive.

FIG. 2 shows an arrangement with several type bars 10 in various sections "-11 and III--III and in the elevation IV, as indicated in FIG. I. The pneumatic drive on the underside of the type bar arrangement is shown in side elevation. From the right-hand section IIII the nature of the feeding of the pulsating pressure into the arcuate pressure chamber 58 via the connecting line 80, the bore 60 and the transverse bore 52 is clearly to be seen. The parts of the pneumatic drive on the underside of the arrangement shown illustrate the assignment bf the pneumatic drive as individual units to all type bars 10 present in the side elevation of FIG. 2.

Section IIII shows the type bar segment 48 in partsectional representation. At its upper non-sectional end the slots 18 for the guide of the type bars 10 can be seen. Section III-III, which is displaced somewhat to the right by comparison to the Section IIII of FIG. 1, but in FIG. 2 is shown on the left next to Section IIII, reveals the arrangement of the selector slide valves 69 in their bores 62 in the drive segment 54. In addition there can be seen the flattened portions 70 of the selector slide valves 69 which, in dependence upon the setting of the arcuate selector bar arrangement 72, can fall into gaps formed by a particular mutual disposition of the cut-away portions 73. Furthermore. the coded distribution and dimensioning of the cut-away portions 73 on the inner periphery of a selector bar can be seen. By means of a slight displacement in the peripheral direction the selector bars can be adjusted mutually in a respective manner such that the flattened portion 70 of only a single prescribed selector slide valve 69 can engage lockingly in a gap. Arrows indicate the movement of the selector slide valves 69 in the radial direction.

It will further be seen how the drive segment 54 is po sitioned with respect to the type bar segment 48 and the way in which the arcuate pressure chamber 58 runs between the two segments 54 and 48. As already explained a pulsating pressure is continuously available, which pressure produces the pneumatic drive.

Finally, the side elevation IV, shows several type bars 10 with their type characters l2 and enables the nature of the overall writing arrangement with respect to the platen 24 to be understood.

FIG. 3 is a curve connecting pneumatic pressure p and displacement a of the diaphragm (ordinates) with the angular position in time wt (ahscissae) of the drive phragm to move up and down, and these two movements' in different directions produce excess and re- (ill shaft I20 relative to a zero position. The curve ignores pressure equalisation occurring in any particular position. The rotation of the drive shaft 120 causes the dia duced pressure respectively relative to atmosphere and with a frequency that is dependent on the speed of rev olution of the drive shaft 120. The representation in FIG.3, shows, as the initial state corresponding to the position shown in FIG. I, a vacuum having the value -p, which, as a result of the rotation of the drive shaft I20 by 1r is converted into a pressure +p, with the diaphragm passing through the central position when the pressure is zero. In this representation relative values are concerned whose magnitudes p and +p state a reduced pressure and excess pressure relative respectively to normal pressure. If no allowance is made for pressure equalisation or mechanical side-effects, a pressure variation with time of practically sinusoidal form would be generated in the pneumatic chamber 98, so that the curve of FIG. 3 is also a curve of displacement +A and A respectively of the diaphragm 100.

FIG. 4 typifies the actual course of the pressure in the pneumatic chamber 98 and in the arcuate pressure chamber 58 and, assuming an actuated selector slide valve 69 also shows the the time-varying force acting on the piston 46 which ultimately causes the type bar 10 to move. This representation assumes that, as a consequence of ceretain mechanical tolerances and because a certain time is required for the control movement of the selector slide valve 69 and the related in crease in volume of the pressure chamber 58 to occur. the increase in pressure in front of the piston 46 begins at a point in time that differs from zero time and zero angular position of the drive shaft 120. Following the pressure equalisation with atmosphere that ensues in this position, the pressure increases to a peak value of +Pk, when the piston 46 has already moved in its bore 44 and the type bar 10 has already been moved towards the platen 24. During this part of the curve (J to +Pk) the pressure continues to rise continuously in front of the piston 46 despite the size of the pneumatic chamber 98, because the volume that it frees is considerably less than that of the pneumatic chamber 98. The pressure valve +Pk is also higher than the value +P shown in FIG. 3, because during actual functioning a pressure equalisation takes place in the starting position shown in FIGv l and the compression process begins with at' mospheric pressure as the starting pressure.

The overall design is such that on reaching the pressure +Pk the drive to the type bar 10 comes to an end. At this point in time the bore 65 is opened by the piston 46 as already described, so that'a comparatively steep fall of pressure occurs in the system.

As already explained, the final portion of the movement of the type bar 10 ensues by virtue of the kinetic energy that has been imparted to it. Following striking of the platen 24 by the type character 12, the buffer stop 22 initiates the return movement of the type bar 10 and the positive link between the type bar I0 and the piston 46 via the intermediate lever bar 26 and the drive lever bar 36 causes the piston 46 to be moved backwards and closes the opening to the bore 65. The further rotation of the drive shaft causes the diaphragm 100 to move downwards, so that a vacuum is formed in the control system and in the arcuate pres sure chamber 58, as is shown in FIG. 4 by the negative course of the pressure eurve to a negative peak Pk. The negative pressure part of the curve to the extreme value Pk is not necessarily and is not shown as symmetrical lth respect to the abovedescribed positive course of the pressure curve. At a predetermined pressure between Zero or atmosphere and the value Pk the selector slide valve 69 responds and overcomes the retaining force exerted by the magnetic strip 79, so that the reduced diameter portion 68 of the selector slide valve 69 once more creates a connection between the bore 64 and the duct 66, to open the piston chamber to atmosphere.

The further course of the curve between Pk and zero now ensues with the mechanical parts of the apparatus in their rest positions, the further rotation of the drive shaft 120 alone governing the variation in pressure. When the drive shaft 120 inside its sleeve 116 once more approaches the position 211' shown in FIG. I, the pressure equalisation between the pneumatic chamber 98, and atmosphere ensues via the diaphragm bore 121, the flexible joint 114 and the bores 122 and 124, so that the atmospheric pressure is restored in the pneumatic control system, as is indicated in FIG. 4 by the steeply ascending part of the negative portion of the pressure distribution curve.

FIG. 5 shows an embodiment in which what may be called a two-part opposed phase drive is provided. In FIG. 5 there are many parts which correspond with parts of the apparatus in FIG. 1. Such parts are identifled in FIG. 5 by references the last two figures of which are the same as the two-figure references used for the corresponding parts in FIG. 1. Here there are two pneumatic chambers 298 and 298a which provide pumping action as the result of a common rotary drive. Control of the pressure relationships in the two pneumatic chambers 298 and 298a is effected by means of two control slide valves 326 and 3260 in bores 344 and 344a in a bearing frame 286. The bearing frame 286 holds the two-part pneumatic drive between two side plates, transverse rods 290 and 294 being provided as bearing elements between the side plates and, for the purpose of providing asymmetrical drive, certain moving parts are present in duplicate in a manner to be described later. They are connected with one another by means of moving transverse rods, which are shown shaded in FIG. 5. All this will be clearer later.

The writing mechanism shown in FIG. 5 together with the pneumatic chamber 298 is generally similar to that already described, there being a generally similar pneumatic control. The second pneumatic chamber 298a serves merely to return the type bar 210 to its rest position on a magnetic strip 250 following a strike, so that the generation of vacuum (as in the embodiment of FIG. 1) is unnecessary for this purpose, the return of the type bar 210 being also effected by pressure. The two pneumatic chambers 298 and 298a work in phase opposition, i.e. they act with their phases displaced by 180 or 11' respectively. This is preferred but is not essential for, as will be apparent later, a different relative phase displacement could be used.

The process of pneumatic control for the outward movement of the type bar 210 (mounted in a type bar segment 248) is effected in similar manner to that already described for FIG. I. In accordance with the ad justment of a selector bar arrangement 272, which is secured to the drive segment 254 by the intermediary of the parts 276 and 278 and is adjusted on guide pins 274, the flattened portion 270 of a selector slide valve 269 provided for each type bar 210 can engage lockingly in a gap of the selector bar arrangement 2'72 and can then be retained on a magnetic strip 279. Thus, when pressure is produced in the pneumatic chamber 298, the pressure generated is passed to an arcuate pressure chamber 258 via a duct 288, a connecting line 280 secured by means of connecting and union elements 284 and 282, a bore 260 and a transverse bore 252, and, as a result of the descent of the selector slide valve 269 in its bore 262, passes through a bore 264 to act on a piston 246 in a bore 244.

In this writing mechanism in which the return movement of the type bar also ensues under positive pressure, the pressure chamber used for the outward movement will be hereinafter termed the call chamber, and an arcuate pressure chamber used for the return movement will be hereinafter termed recall chamher.

The effect of the pressure on the piston 246 drives the upper part 240 of the drive lever bar 236 to the right. This lever bar is, in the construction of FIG. 5, doubled-ended and a slot 242 is provided for it in the drive segment 254. The lever bar 236 accordingly swings clockwise on its arcuate bearing axis 238, and causes the type bar 210, (shown broken-away in FIG. 5) to swing round towards the piston (not shown in FIG. 5), the drive to the type bar being, as in FIG. 1, through tooth gearing on the lever bar 236, the intermediate lever bar 226 and the type bar 210. The lower arm 241 of the drive lever bar 236 of course moves to the left displacing to the left a piston 247 in a bore 245. While compression in the call chamber 258 acts on the type bars 210 via the selector and drive elements until a connection to atmosphere is established via a bore 265, simultaneously expansion in a recall chamber 259 has no effect on the type bar 210 by virtue of a connection 342a to atmosphere produced by the control slide valve 326a. The recall chamber 259 is not used to aid the call-up chamber 258, because suction generated inside the former would act not only on the selected type bar 210 but on all type bars, selector slide valves 269 being assigned only to the call chamber 258.

During the return movement of the type bar the full compression pressure in the recall chamber 259 acts on all pistons 247. This pressure is led to it via a duct 288a a connecting line 2800 secured by means of union and connection elements 282a and 284a and a bore 260a. However, as all pistons except one are located in the rest position, only this one piston 247 can be moved. The reduced diameter 268 of the selector slide valve 269 together with the bore 266 leading to atmosphere serves the function of equalising the pressure during the return movement of the piston 246 as already described for arrangement of FIG. 1.

The two pneumatic chambers 298 and 298a are controlled by a common rotary drive. Each is constructed similarly to the chamber 98 of FIG. 1 and each has a diaphragm 300 or.300a with diaphragm plates 301 and 304 or 301a and 304a. Respective frames 302 and 3020 are provided having respective extensions 312 and 312a to which are imparted oscillatory movement. The rotary drive consists essentially of a square sectioned drive shaft 320 which may be arranged eccentrically inside a sleeve 318. This sleeve 318 is provided with four crank elements which are mutually displaced by about of which only two, 306 and 307 are revealed in the section shown in FIG. 5. The crank element 306 is coupled directly with a rocker arm 322 at a pivot pin 330, so that as a result of the rotation of the drive shaft 320 inside the eccentric sleeve 318 an oscillatory movement is transmitted to links 338 on pivot axes 336 and 310, and drive the extension 312 of the diaphragm plate 304 directly. The two rocker arms 332 are each mounted on one bearing point 334 in the bearing frame 286. A similar movement is imparted to the other diaphragm plate 304a via connecting bars 340 which couple the rocker arms 332 with like rocker arms 332a each secured to the bearing point 3340 in the bearing frame 286. These second rocker arms 32211 are coupled via links 3380 on pivot axes 336a and 3100 with the extensions 3120 on the diaphragm plates 3040 of the pneumatic chamber 2980. This drive coupling effects a positive phase-displaced working on the diaphragms in the two pneumatic chambers 298 and 2980.

The control slide valves 326 and 326a are provided for pressure equalisation in the pneumatic chambers 298 and 2980 and each has a portion of reduced diameter as shown. This portion can selectively connect a duct 324 or a duct 342a with atmosphere in dependence on the position of the respective control slide 326 and 326a respectively. The ducts 324 and 3240 lead to the pneumatic chambers 298 and 298a respectively, so that the pressure equalisation in the pneumatic chambers 298 and 29811 and hence in the call chamber 258 and the recall chamber 259 takes place through this channel. The reciprocating drive of the control slides 326 and 326a is effected on their outer projecting ends 360 and 3600. These projecting ends 360 and 360a are engaged by two connecting slide valves 354 which can move horizontally (as viewed in FIG. 5) by virtue of a pin and slot connection comprising a pin 358 and a slot 356. The second crank ele ments 307 on the eccentric sleeve 318 causes direction-changing levers 348 to move, namely on an articulated joint 346 about a bearing point 350, on which the direction-changing levers 348 are connected with the bearing frame 286. The direction-changing levers 348 are connected with one another via a transverse rod 352, on which their coupling with the control slide valves 326 and 326a via the connecting sliders 354 also ensues.

The rotary device shown in FIG. 5 is symmetrical. At both its ends facing a respective side plate the drive shaft 320 is provided with two crank elements 306 and 307. Accordingly, two rocker arms 332 and 332a, too, are provided on either side of the pneumatic drive. A connecting slide valve 354, a direction-changing lever 348 and a connecting rod 340 are similarly provided in duplicate. These elements are so connected as to provide a symmetrical drive by means of transverse rods 336, 336a and 352, which are shown in section in FIG. 5.

The action of the apparatus shown in FIG. 5 is now easy to appreciate. Rotation of the drive shaft 320 produces a rhythmic generation of pressure pulses in the pneumatic chambers 298 and 298a. As already described a respective lever arm 240 or 241 of the drive lever bar 236 is moved to the right by the appropriate piston 246 or 247. At the same time the respective other lever arm with its associated piston is moved to the left. During these events the control slide valves 326 and 3260 are driven directly by the drive shaft 320 in such a way that pressure equalisation as has already been described with reference to FIG. I, ensues via the ducts 342 and 342a. It needs to be considered, where applicable. that the respectively lockingly engaged selector slider 269 initially must be brought into its rest position by a suction effect linked to the expansion of the pneumatic chamber 298 while the duct 342 is closed off.

By suitably dimensionally the control slide valves 326 and 326a the movement of the type bar 210 and its type character 212 towards the platen may be made such that at the decisive moment when the type character 212 is just about to strike the platen. the drive to the type bar 210 ceases so that, at the moment of striking, the type bar 210 has only the kinetic energy imparted to its during its outward movement. In this way it is ensured that the record carrier on the platen is not hit too hard during the writing process, but just hard enough for optimum writing. To achieve this it is merely necessary so to dimension the control slide valves 326 and 326a that, at the correct moment, during the outward movement of the type bars 210, the connection between the duct 324a and atmosphere is opened. In fact by having control slide valves 326 and 326a having different dimensions, and selecting the most suitable ones for insertion it is possible to have a machine which can be thus adjusted to suit different requirements as regards writing speed, writing quality and writing intensity or where required, to work with a certain phase displacement between call and recall chamber.

FIG. 6 shows an embodiment of a writing mechanism in which, again, a double ended drive lever bar 436 is used. Here, as in FIG. 5, parts corresponding with parts in the embodiment of FIG. 1 are indicated with references the last two figures of which are the same as the two-figure references used for the corresponding parts in FIG. 1. In FIG. 6 the type bar segment is referenced 448 and is secured to a retaining device 449. The working of the type bar movement is similar to that de scribed in FIG. 5, but an alternative form of a selector bar arrangement 472 with selector bars adjustably secured on the drive segment 454 by the intermediary of 478 is used. A different pneumatic drive arrangement which works with continuously fed compressed air and is secured on a retaining plate 512 is provided. Com pressed air supplied from an air line 516 is divided into pressure pulses by a rotating control sleeve 500 and is fed respectively to one or other of two different connecting lines 480 and 465 secured with union and connecting elements 482 and 484. For this purpose the control sleeve 500 has peripheral grooves 504 which, in different positions of the rotating control sleeve 500, make the difference air connections. The peripheral grooves 504 are so dimensioned that, in conjunction with the inner wall of the body 514, channels are formed which move past supply and discharge bores 506, 508, 510 in the said body 514 as the control sleeve rotates. In this way connections to these bores are established. for the required control periods.

In the writing mechanism shown in FIG. 6 a call chamber 458 and a recall chamber 459 are provided in a drive segment 459. These chambers communicate with the connecting lines 465 and 480. The call chamber 458 is connected with the connecting line 465 via a transverse bore 461 and a duct 463. As in the previously described embodiments. pressure equalisation with atmosphere takes place in certain positions of the pneumatic drive, by the control sleeve 500. This is done by providing the control sleeve 500 with at least one radial bore 526 (FIG. 8), through which one or its peripheral grooves 504 is put into communication with atmosphere in predetermined positions via a duct pro vided between the control sleeve 500 and the drive shaft 502.

The functioning of the writing mechanism illustrated in FIG. 6 is one rotation of the drive shaft 502 will now be described. Assume initially that the call chamber 458 is not in communication with the pressure line 516. This will be the case when control sleeve 500 is in a position in which none of its peripheral grooves 504 makes such a connection possible. However, the call chamber 458 is connected with a bore 506 via the ducts 461 and 463 and the line 465, which bore 506 is, in the initial position of the drive shaft 502 under consider ation, connected with atmosphere via one of its peripheral grooves 504. This connection is blocked when the drive shaft 502 turns through a small angle and remains blocked until a position of about l50 with respect to the starting position has been reached. The selector bar arrangement 472 is so adjusted that, during the rotation phase from to 30 the gap that it forms is located underneath an intermediate element 470, so that the latter can lockingly engage in it and be retained by the magnetic strip 479. The intermediate elements 470 are held on a magnetic strip 471 in their rest position (shown in FIG. 6) said strip 471 being secured to the typ bar segment 448. When a rotation through 30 has ensued the call chamber 458 becomes connected with the pressure fed in through the line 516, this connection being made via a peripheral groove 504 in the control sleeve 500, the line 465 and the ducts 463 and 461. The pressure in the call chamber 458 now actuates that selector slide valve 469 whose intermediate element 470 happens to be opposite the gap formed with the selector bar arrangement 472. By virtue of a locking engagement in this gap the selector slide valve 469 gives access to a bore 464 leading to the piston 446, so that the piston 466 is moved to the right from the position shown in FIG. 6. During this event the piston 446 acts on one arm 440 of a drive lever bar 436, so that said bar pivots clockwise on its axis 438 and the type bar 410 is moved from the magnetic strip 450 towards the platen 424 by means of the toothed intermediate lever bar 426. The type character 412 accordingly moves over the arc of the circle 420 and strikes the record carrier on the platen. During this even the lower lever arm 441 of the lever bar 436 causes a piston 447 to be moved to the left from the position that it occupies in FIG. 6, so that the volume in front of the piston 447 in the recall chamber 459 and in the bore 445 connected with it diminishes. To prevent compression taking place during this action, the recall chamber 459 is connected with atmosphere via a peripheral groove in the control sleeve 500. Alternatively, pressure equalisation can ensue upwards as soon as the lower part of the selector slide valve 469 has moved past the bore 445 and its reduced diameter portion 464 faces the bore 445.

Pressure is fed to the call chamber 458 until the control sleeve takes up its l position approximately. It is then cut off by the appropriate peripheral groove 504 in the control sleeve 500. The type bar 410 however continued along its path because of the kinetic energy it has gathered and completes its writing movement automatically, while the piston 446 moves until an edge 466a of its bore is reached, after which pressure equalisation with the space in front of the piston 447 takes place. The call chamber 468 is once more connected with atmosphere after further rotation of the control sleeve 500 via the ducts 461, 463, the connecting line 465 and a periphal groove 504 in the control sleeve 500.

The second half of the rotation of the control sleeve 500 serves for the return movement of the type bar. Similar processes now take place in respect of the recall chamber 459 as have already been described for the call chamber 458. However, the movement of the drive lever arm 436 now ensues simultaneously with the return movement of the selector slide valve 469. For this purpose the call diameter 459 is connected with the pressure line 516 via the connecting line 480 and a peripheral groove 504 in the control sleeve 500. Previously, however, at the l position of rotation, its connection with atmosphere is eliminated. At the 2 l 0 position of rotation increase in pressure takes place and is maintained until rotation to about 300 occurs. As a result. the piston 447 is moved to the right and hence the drive lever bar 436 is caused to pivot anti-clockwise to its lower lever arm 441, so that the type bar 412 is returned by its rest position on the magnetic strip 450. At the same time the selector slide valve 469 is pushed upwards, so that it entrains the intermediate element 470 coupled with it in the region of a cut-away portion 473 in the drive segment 464 until it once more reaches the capture range of the magnetic strip 471, and is once more retained in its rest position. At this stage the bore 464 in front of the piston 446 is connected with atmospheric via the connection formed by the reduced diameter portion 468 of the selector slide valve 469 in the bore 460.

FIG. 7 is a view of the pneumatic drive of FIG. 6 taken on the line VII-VII of that figure. Referring to FIG. 7 the sleeve 500 of FIG. 6 is arranged in a block 514 on the drive shaft 502 and can be continuously rotated by it. It may, for example, be held on one end by a disc 522, while its other end is retained by a nut 524. Several bores 510 are provided in the block 514, some proceeding radially to the control sleeve 500 and some being in the longitudinal direction of the sleeve. In accordance with their functions certain of these bores are sealed with respect to atmosphere with suitable sealing element. The lines 465 and 480 (FIG. 6) leading to the type bar communicate with and are above the vertical bores 506 and 508. The arrangement may be mounted on the plate 512 which may be part of the framework of the writing machine.

FIG. 8 shows the control sleeve 500 itself. It has four peripheral grooves 504, which are so arranged and of such length that during rotation of the sleeve they provide through the bores 510 the control of a writing operation, as already described with reference to FIG. 6. FIGS. 9 to 12 illustrate, by way of example, a possible arrangement of the four peripheral grooves 504. These figures are, respectively, views on the sections IX, X, XI and X11 of FIG. 8. Other forms and arrangements of grooving are, of course, possible.

FIG. 13 is a diagram illustrating the working of a writing mechanism. for example as already illustrated and explained with reference to FIGS. 5 to 12. The representation of FIG. 13 covers one rotation of the drive shaft 502 between 0 and 360, and the key to the diagram is given beneath it, vertical shading representing under pressure, inclined shading representing closed to atmosphere, and no shading representing open to atmosphere. The upper part of the diagram relates to the call chamber and the lower part to the recall chamber.

As will be seen, and in correspondence with the description already given, the call chamber is closed very shortly after (it is shown in the diagram as closed at 0) so that no communication to atmosphere exists. Between 30 and l20 pressure from the pressure line exists inside the call chamber and produces a writing operation by outward movement of the selected type bar. At approximately 150 the call chamber is opened to atmosphere so that the described pressure equalising and return processes can take place. Between about l80 and 330 the recall chamber is closed ofi' from atmosphere and pressure operated return of the type bar to its rest position occurs between about 210 and 300. Between 330 and 360 there occurs pressure equalising in preparation of the chambers for a fresh writing operation, which is repeated when 0 is reached.

FIG. 14 is an overall view of a writing machine in accordance with the invention and having a writing mechanism as described already. Here again the last two figures in the references used in FIG. 14 are chosen to identify parts corresponding with parts in the earlier drawings. in accordance with this method of referencing the platen is referenced 624. As will be seen the type bars 610 with the type characters 612 at their ends are so short that a large number can be fitted in a circular arrangement without the provision of costly mechanical control and actuating elements in the region of their pivot axes. A selector bar arrangement 672, provided around the type bars 610 has cut-away portions arranged in accordance with a predetermined code distribution so that selection of one type bar 610 for operation requires a mutual rotation of the selector bars by a certain amount in the peripheral direction so as to form a gap for the selected type bar. This displacement or re-locating can be effected by pneumatic, hydraulic or electromagnetic drive devices 675, which are connected with the extensions 677 on the selector bars via coupling members 676.

The pneumatic or hydraulic drive can be seen in the lower part of FIG. 14 and may take nay of the forms already described. ln FIG. 14 it is assumed to be assigned to all the type bars 610 in common.

What is claimed is:

l. A writing machine of the kind in which successive writing of characters side by side and line by line is effected on a record carrier by means of a plurality of character carrying type bars arranged side by side of an arcuate pivot axis in their at rest position and adapted, when actuated, to pivot to effect recording at a common recording point, said record carrier mounted on a platen and including means to incrementally move said platen, comprising:

a. a fluid drive,

b. a plurality of fluid driven members, at least one of said fluid driven members associated with each said type bar and operable when fluidly connected to said fluid drive to pivot the type bar associated with said drive member to said common recording point,

c. a plurality of selector valve means, one of said selector valve means associated with each of said fluid driven members,

d. common means fluidly communicating said fluid drive to each of said selector valve means;

e. first means to selectively actuate said selector valve means to selectively fluidly communicate said fluid drive to the driven member to pivot the selected type bar to the common recording point. and

f. second means for fluidly communicating said fluid drive to the driven member of the selected type bar to urge the selected type bar toward its at rest position.

2. A machine as claimed in claim 1,

wherein a drive lever bar is assigned to each drive element and is positively coupled with the respective type bar, and the selector means are so arranged that each can be held in a selected position for a period of time sufficient to allow negative pressure produced in the drive to effect return of a previously driven drive element into its rest position.

3. A machine as claimed in claim I, wherein there is provided at least one pressure chamber which is concentric with the arcuate pivot axis of the type bars and is in constant communication with the drive, the volume of said chamber being limited by each of a number of selector slide valves equal to the number of type bars, each of said slide valves being arranged to be released by the selector means to move into a position in which communication is established between said pressure chamber and an appropriate drive element.

4. A machine as claimed in claim 3 wherein there are two concentric pressure chambers of which one is in constant communication with drive elements which are provided for the type bars and which, if actuated by fluid pressure, return their respective type bars into the rest position.

5. A machine as claimed in claim 4 wherein a double ended drive lever is assigned to each first and second drive element and is positively coupled with the respective type bar.

6. The machine as claimed in claim 4 wherein there is provided means for establishing a connection via the drive between the concentric chamber and atmosphere.

7. A machine as claimed in claim 6 wherein control slide valves coupled with the drive shaft are provided, said control slide valves being arranged when in predetermined positions of said drive shaft to open a connection between the concentric pressure chambers and atmosphere.

8. A machine as claimed in claim 4 wherein connection between the concentric pressure chambers is provided via the rotary valve arrangement.

9. A machine as claimed in claim 8 wherein the rotary valve arrangement comprises a sleeve rotatably mounted on a cylindrical rod and a connection provided between a peripheral groove in the sleeve and the space between said sleeve and said rod.

10. A machine as claimed in claim 8, wherein the first and second concentric pressure chambers are the terminal spaces of a bore, a selector slide valve in the form of a piston rod is arranged inside said bore, both pressure chambers being in communication with peripheral grooves in a rotary sleeve forming part of the rotary valve arrangement and the arrangement being such that in the two terminal positions of the selector slide vaive respectively one of the two drive elements has the space in front of its working surface connected with at mosphere.

11. A machine as claimed in claim 10 wherein the connections to atmosphere run past a portion of the selector slide valve having a reduced diameter.

12. A machine as claimed in claim 3 wherein the selector slide valves are arranged to move each to a rest position to open connections between the respective drive element and atmosphere.

13. A machine as claimed in claim 12 wherein the pressure chamber is connected with atmosphere via the drive in the extreme negative pressure position of said drive.

14. A machine as claimed in claim 13 wherein the drive is provided by a diaphragm pump coupled with an eccentric rotary drive, said connection to atmosphere in the extreme negative pressure position of the drive being provided by bores in the eccentric rotary drive and in the diaphragm and a flexible connection between the eccentric rotary drive and the diaphragm.

15. A machine as claimed in claim 12 wherein the respective selector slide valves are constructed like piston rods and are inside bores connected with the pressure chamber, each slide valve having a portion of reduced diameter provided between its ends, ports being provided in said bores proximate the reduced diameter portion of said slide valve and said slide valve which place said ports in communication with respectively the working space of the respective drive element and atmosphere according to its position.

16. A machine as claimed in claim 3 wherein there is provided means for establishing a connection via the drive between a concentric chamber and atmosphere.

17. A machine as claimed in claim 16 wherein control slide valves coupled with the drive shaft are provided, said control slide valves being arranged when in predetermined positions of said drive shaft to open a connection between the concentric pressure chambers and atmosphere.

18. The invention as defined in claim 1 and in which said fluid drive is a pulsating fluid drive supplying fluid pressure to said selector valve means, said fluid pressure cyclically vacillating between a positive and negative fluid pressure at a frequency equal to an integral multiple of the speed of writing.

19. The invention as defined in claim 18 wherein said actuated selector valve means is actuated during the period of positive fluid pressure and remains actuated into the period of negative pressure. said negative pressure being operable to initiate the return of said driven member to its original position.

20. The invention as defined in claim 19 wherein said negative pressure is operable to urge said actuated selector valve means toward its unactuated position.

21. A machine as claimed in claim 18 wherein the fluid drive is provided by means ofa rotating drive shaft driving at least one pumping device via an eccentric.

22. A machine as claimed in claim 21 wherein there are two pumping devices so coupled with the drive shaft as to work in phase-displaced manner with reference to one another.

23. A machine as claimed in claim 22 wherein the phase displacement is substantially 24. The invention as defined in claim 1 wherein the drive element for moving the type bar to said common recording point is a piston which is arranged inside a bore, and which in a predetermined working position opens a connection between said bore and atmosphere.

25. The invention as defined in claim 1, wherein means are provided for causing the drive force which is applied to move the selected type bar towards its striking position from its rest position to cease before said striking position is reached, said striking position being then reached due to stored kinetic energy in said selected type bar.

26. The invention as defined in claim 1 wherein the fluid drive is a pneumatic drive.

27. A machine as claimed in claim 18 wherein the pulses are derived by means of a rotary valve arrangement which is driven by a rotating drive shaft and to which pressure is supplied from a pressure line.

28. A machine as claimed in claim 27 wherein the rotary valve arrangement comprises a guide block having pressure line port and outlet port, a rotatable sleeve disposed in said block, said rotatable sleeve having peripheral grooves arranged to provide fluid connection intermittently between said pressure line and outlet ports.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,904,013

DATED 1 September 9, 1975 INVENTOR( i Hermann Rummel It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 15, line 20, delete "324" and insert -342.

line 22, delete "324" and "324a" and insert -342-- and --342a--.

Column 17, line 37, delete "466" and insert --446-.

line 46, delete "even" and insert --event-. line 66, delete "447' and insert 446-. line 67, delete "468" and insert 458--.

Column 18, line 9, delete "arm" and insert --bar--,.

line 11, delete "diameter" and insert -chamber-. line 20, delete "to" and insert -on--. line 21, delete "by" and insert -to--. line 25, delete "464" and insert --454--. line 61, delete "5" and insert -6--.

Signed and Scaled this tenth Day of February 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmissloner of Patents and Trademarks

Claims (28)

1. A writing machine of the kind in which successive writing of characters side by side and line by line is effected on a record carrier by means of a plurality of character carrying type bars arranged side by side of an arcuate pivot axis in their at rest position and adapted, when actuated, to pivot to effect recording at a common recording point, said record carrier mounted on a platen and including means to incrementally move said platen, comprising: a. a fluid drive, b. a plurality of fluid driven members, at least one of said fluid driven members associated with each said type bar and operable when fluidly connected to said fluid drive to pivot the type bar associated with said drive member to said common recording point, c. a plurality of selector valve means, one of said selector valve means associated with each of said fluid driven members, d. common means fluidly communicating said fluid drive to each of said selector valve means; e. first means to selectively actuate said selector valve means to selectively fluidly communicate said fluid drive to the driven member to pivot the selected type bar to the common recording point, and f. second means for fluidly communicating said fluid drive to the driven member of the selected type bar to urge the selected type bar toward its at rest position.

2. A machine as claimed in claim 1, wherein a drive lever bar is assigned to each drive element and is positively coupled with the respective type bar, and the selector means are so arranged that each can be held in a selected position for a period of time sufficient to allow negative pressure produced in the drive to effect return of a previously driven drive element into its rest position.

3. A machine as claimed in claim 1, wherein there is provided at least one pressure chamber which is concentric with the arcuate pivot axis of the type bars and is in constant communication with the drive, the volume of said chamber being limited by each of a number of selector slide valves equal to the number of type bars, each of said slide valves being arranged to be released by the selector means to move into a position in which communication is established between said pressure chamber and an appropriate drive element.

4. A machine as claimed in claim 3 wherein there are two concentric pressure chambers of which one is in constant communication with drive elements which are provided for the type bars and which, if actuated by fluid pressure, return their respective type bars into the rest position.

5. A machine as claimed in claim 4 wherein a double ended drive lever is assigned to each first and second drive element and is positively coupled with the respective type bar.

6. The machine as claimed in claim 4 wherein there is provided means for establishing a connection via the drive between the concentric chamber and atmosphere.

7. A machine as claimed in claim 6 wherein control slide valves coupled with the drive shaft are provided, said control slide valves being arranged when in predetermined positions of said drive shaft to open a connection between the concentric pressure chambers and atmosphere.

8. A machine as claimed in claim 4 wherein connection between the concentric pressure chambers is provided via the rotary valve arrangement.

9. A machine as claimed in claim 8 wherein the rotary valve arrangement comprises a sleeve rotatably mounted on a cylindrical rod and a connection provided between a peripheral groove in the sleeve and the space between said sleeve and said rod.

10. A machine as claimed in claim 8, wherein the first and second concentric pressure chambers are the terminal spaces of a bore, a selector slide valve in the form of a piston rod is arranged inside said bore, both pressure chambers being in communication with peripheral grooves in a rotary sleeve forming part of the rotary valve arrangement and the arrangement being sucH that in the two terminal positions of the selector slide valve respectively one of the two drive elements has the space in front of its working surface connected with atmosphere.

11. A machine as claimed in claim 10 wherein the connections to atmosphere run past a portion of the selector slide valve having a reduced diameter.

12. A machine as claimed in claim 3 wherein the selector slide valves are arranged to move each to a rest position to open connections between the respective drive element and atmosphere.

13. A machine as claimed in claim 12 wherein the pressure chamber is connected with atmosphere via the drive in the extreme negative pressure position of said drive.

14. A machine as claimed in claim 13 wherein the drive is provided by a diaphragm pump coupled with an eccentric rotary drive, said connection to atmosphere in the extreme negative pressure position of the drive being provided by bores in the eccentric rotary drive and in the diaphragm and a flexible connection between the eccentric rotary drive and the diaphragm.

15. A machine as claimed in claim 12 wherein the respective selector slide valves are constructed like piston rods and are inside bores connected with the pressure chamber, each slide valve having a portion of reduced diameter provided between its ends, ports being provided in said bores proximate the reduced diameter portion of said slide valve and said slide valve which place said ports in communication with respectively the working space of the respective drive element and atmosphere according to its position.

16. A machine as claimed in claim 3 wherein there is provided means for establishing a connection via the drive between a concentric chamber and atmosphere.

17. A machine as claimed in claim 16 wherein control slide valves coupled with the drive shaft are provided, said control slide valves being arranged when in predetermined positions of said drive shaft to open a connection between the concentric pressure chambers and atmosphere.

18. The invention as defined in claim 1 and in which said fluid drive is a pulsating fluid drive supplying fluid pressure to said selector valve means, said fluid pressure cyclically vacillating between a positive and negative fluid pressure at a frequency equal to an integral multiple of the speed of writing.

19. The invention as defined in claim 18 wherein said actuated selector valve means is actuated during the period of positive fluid pressure and remains actuated into the period of negative pressure, said negative pressure being operable to initiate the return of said driven member to its original position.

20. The invention as defined in claim 19 wherein said negative pressure is operable to urge said actuated selector valve means toward its unactuated position.

21. A machine as claimed in claim 18 wherein the fluid drive is provided by means of a rotating drive shaft driving at least one pumping device via an eccentric.

22. A machine as claimed in claim 21 wherein there are two pumping devices so coupled with the drive shaft as to work in phase-displaced manner with reference to one another.

23. A machine as claimed in claim 22 wherein the phase displacement is substantially 180*.

24. The invention as defined in claim 1 wherein the drive element for moving the type bar to said common recording point is a piston which is arranged inside a bore, and which in a predetermined working position opens a connection between said bore and atmosphere.

25. The invention as defined in claim 1, wherein means are provided for causing the drive force which is applied to move the selected type bar towards its striking position from its rest position to cease before said striking position is reached, said striking position being then reached due to stored kinetic energy in said selected type bar.

26. The invention as defined in claim 1 wherein the fluid drive is a pneumatic drive.

27. A machine as claimed in claim 18 wherein the pulses are Derived by means of a rotary valve arrangement which is driven by a rotating drive shaft and to which pressure is supplied from a pressure line.

28. A machine as claimed in claim 27 wherein the rotary valve arrangement comprises a guide block having pressure line port and outlet port, a rotatable sleeve disposed in said block, said rotatable sleeve having peripheral grooves arranged to provide fluid connection intermittently between said pressure line and outlet ports.

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