FR2618100A1 - PERFECTED HAMMER RANGE PRINTER AND THIS ROW OF HAMMERES - Google Patents

Abstract

A printer with an improved hammer array is disclosed. The row 18 of hammers is mounted in a chamber formed in a base 26 of a shuttle 10 so as to be able to perform a reciprocating movement therein under the action of a cam mechanism 66. A fan 24 delivers air under it. pressure in an air chamber 20 and through a base support member 14 so that this air is channeled so as to pass over the control coils of the printing hammers. Field of application: impact printers.

Description

The invention relates to impact printers, and more particularly

  a line-by-line dot matrix printer in which an elongated row of hammers is reciprocated with respect to a length of printing paper, while magnetic hammer actuators mounted along the length of the row of hammers; together with hammer springs, are selectively activated to release the hammer springs and thereby print dots on the

length of printing paper.

  Printers are known in which an elongated row of hammers is bi-directionally reciprocated with respect to a length of printing paper for effecting dot impact printing. An example of such a printer is described

  in U.S. Patent No. 3,941,051.

  The above-mentioned patent describes a line-by-line dot matrix printer with an elongated row of hammers animated by bidirectional reciprocating motion.

  by a cam drive assembly. A turntable

  Tape, mounted in the printer in the immediate vicinity of the row of hammers, places a length of ink ribbon between several hammer springs in a parallel arrangement and spaced along the length of the row of hammers, and an adjacent plate or cylinder. A length of printing paper arranged between the length of the ink ribbon and the platen is advanced step by step through the printing station defined by the space between the row of hammers and the platen, the advance being ensured

by a coaching device.

  The printer described in the aforementioned patent

  makes an impression in the form of a dot matrix.

  While the row of hammers is reciprocated transversely across the printing paper, some, various, hammer springs located along the length of the row are released or triggered from their retracted positions, into which they are loaded by springs and in which they are normally retained by means of magnetic actuators of associated hammers. When each hammer spring is released or triggered, a free upper end of this spring, which carries an impact tip for printing a point, flies out of the retracted position forward so that the impact tip hits the length of ink ribbon against the print paper to print a stitch. The hammer spring then rebounds into the retracted position. Each of the magnetic hammer actuators comprises a permanent magnet connected to the free upper end of an associated hammer spring via a pole piece. The permanent magnet normally holds the hammer spring in the retracted position, loaded by a spring, in which this spring

  hammer is ready to be released or triggered. The action-

  hammer magnetic neur also comprises a magnetic coil surrounding the pole piece and having the effect, when momentarily excited, of overcoming the effects of the permanent magnet and releasing the spring of

  hammer to print a dot on the printing paper.

  In the rows of hammers of the type described in the aforementioned Patent No. 3,941,051, the various hammer springs are released or triggered rapidly and repeatedly while the row of hammers reciprocates back and forth on the length of the printing paper. The repeated excitation of the magnetic coils causes their rapid heating up, which makes it necessary to provide cooling of the coils. A device for cooling the coils is described in U.S. NI 4,033,255. This device uses cooling fins mounted on top of the magnetic coils. The cooling fins absorb the heat coming from the magnetic coils and easily give up the heat.to the air circulated under

  pressure on the fins. Another cooling device

  of the coils is described in US Pat.

  United States of America No. 4,044,668. In the latter patent, pressurized air is directed towards the rear of the row of hammers from where it enters the interior of the row through openings in a rear wall as well as the opposite open ends of the row of hammers. The air inside the row of hammers rises on the magnetic coils and leaves the

  the printer through a filtered exit passage.

  Although the cooling devices of the magnetic coils described in the patents No. 4,044,668

  and N 4033 255 cited above effectively ensure the cooling

  in most cases, these concepts are limited by their ability to adapt to certain

  configurations of rows of hammers. This is

  particularly true in the case of hammer rows of more recent designs in which the required printing speed may require a much larger number of hammer springs to be installed in a row of hammers of given dimensions. The design of magnetic hammer actuators can be revised to accommodate an increased number of hammer springs which are generally smaller in size and closer together. The row of high performance hammers

  thus obtained does not usually lend itself well to

  same, cooling using fins mounted on coils or configurations in which air is simply passed through

  inside the row of hammers.

  In rows of hammers of the type described in the aforementioned Patent No. 3,941,051, a certain degree of magnetic interaction occurs between adjacent magnetic actuators, due to their close physical proximity and, in some cases, the use of common components. Some degree of magnetic interaction is tolerable, especially when the performance requirements are not particularly great. As printing speeds increase, and in particular when the magnetic hammer actuators must be closer together to accommodate larger numbers of hammer springs, the problem of magnetic interaction becomes

much more serious.

  To minimize the effects of the magnetic interaction between adjacent magnetic hammer actuators, a number of techniques have been used. One technique which is described in U.S. Patent 4,280,404 is to vary the current applied to the coils as a function of the number of hammers triggered simultaneously. In another technique which is described in U.S. Patent No. 4,386,563, alternate hammer springs are triggered at different points in each trigger interval so that adjacent hammer springs are not triggered simultaneously. . Although the variants of hammer release techniques described in the two aforementioned patents are effective in minimizing the effects of magnetic interaction for many applications, it would be advantageous to avoid the need for such techniques and equipment and complications. additional operating conditions that result. Ideally, the tripping times

  hammers should be independent of these

  in such a way that the spacing of the dots on the paper

can vary infinitely.

  Most of the rows of hammers of the type described in the aforementioned Patent No. 3,941,051 comprise two elongated, generally cylindrical, pins fixed at their opposite ends and slidably mounted in bearings to allow reciprocating movement of the row of hammers. . Usually, these axes are of solid configuration and are attached to the opposite ends of the row of hammers, for example by gluing. In spite of the important care with which the bonding of the pins is carried out on the opposite ends of the row of hammers, the axes do not always align accurately on a common longitudinal axis of the row of hammers, and the resistance of the connection made between the axes and the row of hammers sometimes proves unsuitable. Therefore, it is possible to improve the arrangement of

  mounting axes in rows of hammers of this type.

  In rows of hammers of the type described in the aforementioned Patent No. 3,941,051, the hammer springs, which are placed in a generally parallel arrangement and spaced along the length of the row of hammers, are fixed by their lower ends to a surface mounting hammers extending the length of the row. Usually, each hammer spring is attached to the mounting surface by a relatively short screw which passes through a mounting plate, through the lower end of the hammer spring and which then enters a screw hole sinking into the row of hammers from the mounting surface of the hammer springs. Due to design considerations of the hammer row, the screw holes are usually of limited length, requiring the use of relatively short screws for mounting the hammer springs. Often, debris such as dirt and oil from surrounding parts accumulates between the tip of the screw and the rear portion of the screw hole after the screw has been laid. A more desirable configuration of hammer rows would thus not limit the size of the hammer spring mounting screws or cause debris to be trapped in the screw holes. In rows of hammers of the type described in the aforementioned patent N 3 941 051, a hood assembly is mounted on the row of hammers at the interface between

  this row and an adjacent paper board.

  The hood assembly receives a length of ink ribbon from the tape deck and maintains the length of ink ribbon between the impact tips of the hammer springs and the printing paper carried by the platen. When the various hammer springs are triggered, the impact tips for dot printing pass through openings in the bonnet assembly such that small portions of the length of the tape

  inking can be struck against the printing paper.

  if we. A lower edge of the hood assembly is usually

  It is fixed by means of screws or other suitable means of attachment to a lower part of the length of the hammer row in the immediate vicinity of the lower ends of the mounting of the hammer springs. The opposite upper edge of the hood assembly is desirably attached in a fixed disposition relative to the

row of hammers.

  In the particular row of hammers described in the aforementioned US Patent No. 3,941,051, substantially all of the structure of the hammer array carries a magnetic flux from the various permanent magnets of the magnetic hammer actuators. The upper edge of the bonnet assembly is conveniently connected to the fixed reference formed by an upper portion of the hammer row using the magnetic pull present

  practically in the entire row of hammers.

  However, in hammer array configurations in which the magnetic circuits are confined to much smaller areas and do not extend across a substantial portion of the hammer bank, other means must be used to secure the edge.

  top of the hood assembly to the row of hammers.

  It would therefore be desirable to have an improved air-cooling system of the rows of hammers, which eliminates the need for fins radiating heat on the magnetic coils and which optimizes the cooling action of the pressurized air in motion. inside a confined space in the row of hammers. It would further be advantageous to provide a row of hammers in which the magnetic interaction between magnetic hammer actuators, closely spaced, is minimized so that the triggering of each hammer spring can take place independently of the triggers of other springs of hammers and without the need to resort to compensation techniques such as a variation of the

  current of the coils or an offset of the trigger times

  is lying. It would also be advantageous to avoid having to fix separate pins on the opposite ends of the row of hammers for mounting this row so that it can reciprocate. It would still be advantageous to provide a row of hammers allowing the use of longer hammer spring mounting screws without debris retention in the rear portions of the screw holes. It would also be advantageous to provide other arrangements for securing the upper edge of the bonnet assembly to the row of hammers in cases where this row is not fully magnetized by the permanent magnets of the magnetic hammer actuators. It would also be advantageous to provide a row of hammers in which parts of the elements in the magnetic actuators of the hammers are configured to improve the containment and flow of the cooling air over them.

the magnetic coils.

  The above objects and other objects and features of the invention are realized by an array of improved design hammers, designed to solve many of the problems posed by

  rows of hammers of the prior art.

  Rows of hammers in accordance with the invention utilize an improved air cooling system in which pressurized air is introduced into a common manifold formed at the bottom of an elongated cavity within a shuttle hub in which is

  the row of hammers. The latter presents an agency

  an aperture spaced along its length, which openings suck air from the common manifold into a first manifold located in an area between the hammer springs and the hammer bank below the magnetic coils, in such a way that Air is introduced into the first manifold in a turbulent state at high speed. As a result, cooling is maximized within the confined space of the first manifold and in the presence of a large number of coils.

magnetic to cool.

  In a preferred arrangement of a row of hammers according to the invention, the openings extending through the row of hammers from the common manifold comprise first and second groups of openings. The openings of the first group extend approximately vertically between the bottom of the row of hammers and the first collector. Each opening of the second group extends approximately horizontally between the rear of the row of hammers, at an upper part of the common manifold, and the first manifold. Each opening of the second group extends through an elongated cavity within the hammer row, which forms a second manifold. In addition, the positions of the openings of the first and second groups are shifted along the length of the row of hammers. This arrangement raises the speed of

  the air inside the first collector in addition to

  generate considerable air turbulence so that the cooling of the magnetic coils, at the end

  top of the first collector, be optimized.

  According to one particular feature of the improved air cooling systems of the invention, the magnetic coils are mounted on flanged cores extended at their outer ends, in close proximity to the movable upper parts of the hammer springs. The cheeks of the nuclei extend so as to be closely juxtaposed to each other to form a dam for the air. The dam prevents most of the turbulent air, at high velocity in the first manifold, from escaping laterally by gaps between adjacent hammer springs. On the other hand, the air is essentially confined in the first manifold so as to rise above

  the magnetic coils and to produce the cooling action

desired development.

  In improved hammer rows according to the invention, the magnetic interaction between adjacent magnetic hammer actuators is minimized by the use of essentially independent magnetic circuits which, with one exception, are not interconnected by common magnetic elements. Each magnetic hammer actuator consists of two pole pieces between which is disposed a permanent magnet in the immediate vicinity of the rear parts of these pole pieces and on the front parts of which are mounted the magnetic coils. Each pair of pole pieces and the permanent magnet they frame are mounted in a groove of a common element of aluminum or other non-magnetic material forming part of the row of hammers. The resulting magnetic circuit of each magnetic hammer actuator is confined to the small area delimited by the permanent magnet, the pair of pole pieces, including their magnetic coils, and the small portion of the hammer spring at its end.

  outside extending between the pair of pole pieces.

  The hammer bank includes a group of permanent magnets which are each common to a different group of magnetic hammer actuators so that a portion of a permanent magnet extends through the space between each adjacent pair of magnetic actuators. of hammers. The presence of permanent magnets in the spaces between the magnetic actuators of the hammers serves to significantly limit the amplitude of the magnetic dispersion flux that would otherwise pass between the adjacent rear portions of each pair of pole pieces. In addition, according to the invention, the row of hammers consists of two different elongate elements which contain between them a single axis, made in one piece. The single axis, which extends beyond the opposite ends of the hammer row to facilitate assembly thereof and reciprocates, is of hollow configuration to minimize the weight of the hammer row. At the same time, the presence of a single axis improves the strength of the entire structure while avoiding having to fix different axes to opposite ends of the row of hammers, for example by gluing. In addition, the unique, one-piece configuration of the shaft provides axial alignment of its opposite ends, where the row of hammers is

mounted in opposite bearings.

  In rows of hammers according to the invention, the screw holes for mounting the hammer springs penetrate the hammer row from the mounting surface of the hammer springs and end in some, various, of a first. group of openings forming part of the advanced cooling system. Accordingly, each screw hole is open at both ends, one end being open to the outer side of the hammer row, to the mounting surface of the hammer springs, and the other end open to the inside of the hammer bank. 'one of the

  openings of the first group in the row of hammers.

  Therefore, longer mounting screws of the hammer springs can be put in place, the tip of the screws entering the associated cooling aperture if additional space is needed. In addition, the accumulation of oil or other debris in the

screw hole is avoided.

  In rows of hammers in accordance with the invention, the upper portions of the hood assembly are attached to the hammer row by means of independent sets of magnetic fasteners attached to the row of hammers. This avoids the need to magnetize the totality

  or virtually the entire row of hammers.

  Each magnetic attachment assembly includes two spaced pins mounted on an upper portion of the hammer row and projecting outwardly. An elongated base clip extends between the outer ends of the two pins to which it is attached by its opposite ends. A permanent magnet is attached to an intermediate portion of the base clip between its opposite ends. The magnetic attraction of the permanent magnet maintains an adjacent portion of the hood assembly in contact with the fastener. The magnetic fastener assembly, comprising the base clip, the permanent magnet and the outer ends of the pins, may be ground to have a common reference surface occupying a desired position relative to the hammer row and against which the hood set

is maintained.

  The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting example and in which: FIG. 1 is a perspective view

  exploded main elements of a printer, com-

  taking a shuttle assembly which includes an improved array of hammers according to the inventioon; FIG. 2 is a perspective view of

  elements of Figure 1, as well as a carrier plate

  ribbon and a driver device in a printer; FIG. 3 is an exploded perspective view of the improved row of hammers of FIG. 1, as well as a hood assembly and an elongated plate contained in the shuttle assembly of FIG. 1; - Figure 4 is a perspective view, partially cut away, of the row of hammers of Figure 1; FIG. 5 is a perspective view of the elongate shuttle base of the shuttle assembly of FIG. 1; FIG. 6 is a sectional view of the shuttle base of FIG. 5, mounted on a base support member shown in FIG. 1, together with a

  air chamber and a supply air duct com-

  premium; Figure 7 is a front view of the shuttle assembly of Figure 1; Figure 8 is a top view of the shuttle assembly of Figure 1; Fig. 9 is a rear view of the shuttle assembly of Fig. 1; Figure 10 is a view of the left end of the shuttle assembly of Figure 1; Figure 11 is a view of the right end of the shuttle assembly of Figure 1; Figure 12 is a bottom view of the shuttle assembly of Figure 1; Fig. 13 is a sectional view of the shuttle assembly of Fig. 1 taken along line 13-13 of Fig. 8; Fig. 14 is a perspective view of a small portion of the hammer row of Fig. 1, illustrating how air enters a first manifold according to an improved air cooling system; FIG. 15 is a sectional view of the shuttle assembly of FIG. 1, taken along line 1515 of FIG. 7, showing the opposite ends of FIG.

  the row of hammers in Figure 1 are hermetically closed

  according to the advanced air cooling system; FIG. 16 is a perspective view of four different pairs of pole pieces and a common permanent magnet forming the main parts of four different magnetic hammer actuators of the row of hammers of FIG. 1; FIG. 17 is a front view of the four pairs of pole pieces and the common permanent magnet of the device of FIG. 16, illustrating how the magnetic dispersion flux is limited by the presence of the permanent magnet; Fig. 18 is a sectional view of a portion of the hammer row of Fig. 1, showing an improved arrangement of hammer spring mounting screw holes according to the invention; FIG. 19 is a perspective view of a magnetic fastener assembly according to the invention for mounting an upper part of a bonnet assembly in a fixed position on an upper part of the row of hammers of FIG. 1; FIG. 20 is a front view of a magnetic coil assembly forming part of one of the magnetic hammer actuators and having core flanges configured to form a dam for air in accordance with the improved air cooling system. ; and

  FIG. 21 is a side view of the

  appears to magnetic coils of Figure 20.

  Figure 1 shows a shuttle assembly, as well as other elements of a printer 12 including a base support member 14 on which is mounted a cam drive assembly 16. The shuttle assembly 10 comprises an improved row 18 of hammers according to the invention, described in detail below. The base support member 14 is part of a building structure for the printer 12 and the shuttle assembly 10 is removably mounted on this element. An elongate hollow tube 20, which is mounted on the bottom of the base support member 14, opposite the shuttle assembly 10, is connected by a conduit 22 to a fan 24 or a

other source of compressed air.

  As described in detail in U.S. Patent Application No. 069,486 to Farb et al., Filed July 1, 1987 and entitled

  "PRINTER HAVING INTERCHANGEABLE SHUTTLE ASSEMBLY",

  the shuttle assembly 10 comprises a one-piece modular block which is interchangeable inside the printer 12. In this way, difficult and essential adjustments can be made to the shuttle assembly 10 and to the row 18 of hammers it contains during the manufacture of the assembly 10 in the factory. Then, if it becomes necessary to install or replace the row 18 of hammers while the printer 12 is in service or is in another remote location, the interchangeable shuttle assembly 10, on which the essential settings have already made, is easily installed in the printer 12 or is easily removed. As shown in FIG. 1, the shuttle assembly 10 includes an elongate shuttle base 26 in which the hammer row 18 is mounted. The shuttle base 26 has, at its left end 30, a lug 28 through which an opening 32 passes. The opposite end 34 of the right side of the shuttle base 26 comprises two lugs (not shown in FIG. 1). each traversed by an opening. The shuttle assembly 10 is removably mounted on the base support member 14 by means of three screws 36, 38 and 40. The screw 36 passes into the opening 32 of the tab 28 and enters the element 14 of the base support 36 for attaching the left end 30 of the base 36 of the shuttle to the support member 14. Similarly, the screws 38 and 40 pass through the openings of the legs of the right end. 34 of the base 26 of the shuttle and enter the base support member 14 to attach the right end 34 of the base 26 of the shuttle to the support member 14. A pin 42, which rises from a generally horizontal upper surface 44 of the base support member 14 in the immediate vicinity of the right end 34 of the base 26 of the shuttle, is received in a complementary opening in the bottom of the base 26 of the shuttle to properly position the right end 34 of the base 26 on the base support member 14. The opening for receiving the pin is shown and described below in

look at figure 12.

  As described in the aforementioned NI 069 486 application, the shuttle assembly 10 is easily, but precisely, installed on the base support member 14 inside the printer 12 by lowering the assembly to

  shuttle 10 on the base support member 14 within the

  printer 12 so that the pin 42 enters the complementary opening formed in the underside of the right end 34 of the base 26 of the shuttle. The shuttle assembly 10 is then rotated about the pin 42 to bring the left end 30 of the base 26 forward until a platen retainer plate 46, located at the end left 30, is received in a complementary opening 48 of a trainer

  which is shown in Figure 2. The training

  neur 50 constitutes the left-hand trainer forming part of two pinned drivers 50 and 52 which, together, form the driving device 54 for the printer 12. When the plate 46 for retaining the plate is housed in the complementary opening 48 , the screws 36, 38 and 40 are inserted through the legs and in the element 14 of

  base bracket and they are tight, but not locked.

  After small adjustments to properly orient the shuttle assembly 10 relative to the cam drive assembly 16 and the drive device 54, the screws 36, 38 and 40 are locked. is mounted on the front of the shuttle assembly 10 by means of two screws 58 and 60 as shown on

Figure 2.

  Disassembly of the interchangeable shuttle assembly

  12 of the printer 12 is performed by an inversion of the process just described. The tape deck 56 is removed from the shuttle assembly 10, after which the screws 36, 38 and 40 are removed. This allows the shuttle assembly 10 to be rotated on the pin 42 to remove the

  plate 46 for retaining the plate of the opening

  The shuttle assembly 10 can then be lifted from the element 14 of the spike driver 50.

  base support and removed from the printer 12.

  The shuttle assembly 10 encloses a printing station defined by a small gap of uniform size between the hammer row 18 and an adjacent platen 106. A length of printing paper being disposed in the printing station, as well as In a length of ink ribbon from the tape deck 56, the hammer row 18 prints the print paper in a dot matrix as described below. The printing paper is advanced step by step through the printing station in the shuttle assembly 10, dot line by dot line, conventionally, by means of the driving device 54. The latter does not advance to not print paper upward using the opposing pinned drivers 50 and 52 which engage with perforations in the opposite edges of the

printing paper.

  The cam drive assembly 16 is of suitable conventional design, such as the type disclosed in the aforementioned US Patent No. 3,941,051. The cam drive assembly 16 includes a driven flywheel 64 which is connected to a cam 66. A cam follower assembly 68, which is connected to one end of the hammer row 18, bears against a first A counterweight assembly 70 bears against the side of the cam 66 opposite that of the cam follower assembly 68 and is driven in phase opposition from the row 18

  of hammers under the effect of the rotation of the cam 66.

  The counterweight assembly 70 compensates for the alternating movement

  native of row 18 of hammers to eliminate the

  jolts or other vibratory movements that occur

otherwise.

  The row 18 of hammers, and in particular the magnetic coils of the magnetic actuators of the hammers that it contains, are cooled by a system which uses air under pressure. The pressurized air is produced by the fan 24 which is shown in FIG. 1. The fan 24 delivers pressurized air into the conduit 22 and into the elongated air chamber 20 which is connected to the lower surface of the air. base support member 14 and whose sealing with respect thereto is ensured by a foam seal 72 mounted on the top of the air chamber 20. The top of the air chamber 20 presents an elongated slot 74 through which

  passes the pressurized air in the chamber 20.

  Pressurized air rising through slot 74 enters and passes through a series of four openings 76 in the base support member 14. The openings 76 are arranged in an elongate configuration so as to be disposed above the slot 74 of the air chamber 20 and generally on the same extent as

this slit 74.

  As described below, the underside of the base of the shuttle assembly 10 has four openings which are arranged above the openings 76 of the base support member 14, in alignment, when the assembly shuttle 10 is mounted on this element 14. The pressurized air rising through the openings 76 in the base support member 14 from the air chamber 20 enters the shuttle assembly 10 while passing through the openings located in the bottom of the base 26 of the shuttle. Fig. 3 is an exploded perspective view showing the hammer row 18, a hood assembly 78, an elongate platen assembly 80 and the cam follower assembly 68 housed within the shuttle assembly 10 of which they form part. The row 18 of hammers comprises a single hollow shaft 82 made in one piece, mounted in this row and extending along the length thereof. The opposite ends of the axis 82, which are of hollow cylindrical configuration, project outwardly from opposite ends of the hammer row 18 to form two opposite axis lengths 84 and 86 outside the row. 18 of hammers. As described below, the axis lengths 84 and 86 are received in linear smooth bearings mounted in the shuttle base 26 to allow reciprocating the hammer row 18 along the longitudinal geometric axis of the rotor. 82. The cam roller assembly 68 is mounted on the end of the shaft length 84 and bears against the cam 66 of the cam drive assembly 16 in order to reciprocate the cam. the row 18 of hammers. Figure 4, which is a partially cut-away view, shows how the single axis 82 extends the full length of the hammer row 18, within it. The hood assembly 78, which is mounted on the hammer row 18, receives a length of ink ribbon 58 from the tape deck 56. The hood assembly 78, which is of a configuration folded to include front and rear portions 90 and 92 between which is arranged the length of the ink ribbon 88, is secured, by its lower edge 94, to the row 18 of hammers, along the length thereof. The hood assembly 78 is attached to the hammer row 18 along its lower edge 94, for example by fasteners 96 connected to opposite ends of the bottom edge 94 and attached to opposite ends of the hammer row 18.

by screws 98 and 100.

  An upper edge 102 of the hood assembly 78, opposite the lower edge 94, is secured in a fixed position relative to an upper portion of the hammer row 18 by a plurality of magnetic fastener assemblies 104 mounted at a distance from each other on the along an upper part of the row 18 of hammers. The magnetic fastener assemblies 104, which will be described in more detail below with reference to FIG. 19, can be accurately ground after being mounted on the hammer row 18 so as to define reference surfaces which are arranged accurate with respect to the upper part of the row 18 of hammers. The top edge 102 of the hood assembly 78 is held against the reference surfaces of the magnetic fastener assemblies

104 by magnetic attraction.

  As previously indicated, the hood assembly 78, which is mounted on the hammer row 18, forms a small gap of uniform dimensions to define a printing station in which the paper is located.

  printing. The printing station is formed by the

  appears to hood 78, together with an elongate plate 106 which forms the platinum assembly 80 with two axes 108 and

  located at opposite ends of this deck.

  The plate assembly 80 is mounted in a generally parallel arrangement spaced from the hammer row 18 so that the pins 108 and 110 extend over a

  common geometric axis which is parallel to the geometric axis

  longitudinal axis of the axis 82 of the row 18 of hammers. Platen 106 supports a length of printing paper 112 whose opposite edges have perforations 114. Opposite pinning drivers 50 and 52 shown in Fig. 2 engage with perforations 114 of opposite edges of printing paper 112. to produce a step-by-step movement of the paper

  printing 112 through the printing station.

  In the present example, the row 18 of hammers comprises, in total, 66 hammer springs 116 mounted along its length, in a parallel and spaced arrangement. Four hammer springs 116, only, are shown in Figure 3 for simplicity. The hammer springs 116 are mounted along a hammer spring mounting surface 118 extending over the

  length of the row 18 of hammers. The end

  The bottom of each hammer spring 116 is attached to the mounting surface 118 by a screw 120 which passes through a mounting plate 122, through the lower end of the hammer spring 116 and into a screw hole 124 which sinks into the row 18 of hammers from the

mounting surface 118.

  A different pair of pole pieces 126 and 128, mounted in a groove 130 extending along an upper portion of the hammer row 18, away from the hammer spring mounting surface 118 and substantially parallel to the this surface 118 is associated with each hammer spring 116. The pole pieces 126 and 128 are part of a magnetic actuator for the hammer spring 116. A permanent magnet 132 is disposed between the pole pieces 126 and 128, in the groove 130. A coil assembly 134, forming part of the magnetic hammer actuator comprises a first magnetic coil 136 mounted on the first pole piece 126 and a second magnetic coil 138 mounted on the second pole piece 128. The first and second magnetic coils 136 and 138 are disposed on the pole pieces 126 and 128 outside the groove 130 and in the immediate vicinity of a free upper end of the

hammer spring 116.

  The springs 116 of hammers are made of a resilient magnetic material such as spring steel. Each hammer spring 116 is normally held in a slightly bent, retracted, spring loaded position against the ends of the pole pieces 126 and 128 under the action of the permanent magnet 132 which closes a magnetic circuit passing through the pole pieces. 126 and 128 and an adjacent upper portion of the hammer spring 116. Each of the hammer springs 116 carries an impact tip 140 for the printing of a point, mounted on the free upper end of this spring 116. Each of the impact tips 140 is disposed in the immediate vicinity of a pair. different openings 142 located in the front and rear portions 90 and 92 of

the hood assembly 78.

  During printing and while the hammer row 18 is reciprocated with respect to the plate 106, the various hammer springs 116 are selectively released or "triggered" to print dots along the length of the paper. The release of each hammer spring 116 is effected by an excitation of the first and second coils 136 and 138 of the assembly 134 associated with this spring, this excitation being long enough to overcome the magnetic force. held by the permanent magnet 132 and projecting the free upper end of the hammer spring 116 away from the pole pieces 126 and 128. While the hammer spring 116 moves away from the pole pieces 126 and 128, the impact tip 140 passes through the pair of associated openings 142 of the hood assembly 78 to strike the length of the ink ribbon 88 disposed between the front and rear portions 90 and 92 of the assembly. the hood 78, against the length of printing paper 112 which is supported by the plate 106. After the impact, the hammer spring 116 returns by bouncing in the retracted position against the pole pieces 126 and 128 where it remains in the retracted position in preparation for the next release of the hammer spring 116. A "Kapton" strip 143, extending along the length of the hammer row 18, between the hammer spring mounting surface 118 and the groove 130 containing the pole pieces 126 and 128, dampens the arrival of the spring 116. hammer in the retracted position. The strip 143 of "Kapton", which is adjacent to the intermediate portions of the springs 116 of hammers, consists of several layers of "Kapton" which are superimposed on the

  to each other to form band 143.

  As previously indicated, the cam follower assembly 68 is mounted on the shaft length 84 to drive the hammer row 18 to reciprocate under the action of the cam drive assembly. 16. The cam follower assembly 68 comprises a roller 144 rotatably mounted in a yoke 146 from the outside of which it projects to bear against the cam 66 of the assembly 16. The yoke 146 is connected by a ring 150, located at the rear face of the yoke 146, to a bearing assembly 148. The ring 150 passes through a washer 152, into a shuttle coil spring 154 and into washers 155 to terminate at one end of the bearing assembly 148 surrounded by a reservoir 158 which bears against a lubricant wick 160 in which

  felt on the end of the landing assembly 148.

  The assembly 148 is mounted on a conical end 162 of the axis length 84. A locking screw, which is not shown and which is housed freely inside the ring 150 of the yoke 146, is mounted in the conical end 162 of the axis length 84. The locking screw defines the distance over which the yoke 146 can move away from the tapered end 162 while at the same time allowing limited movement of the yoke 146 to the conical end 162 against the resistance of the

  spring 154, so as to absorb the shocks that occur

  when the roller 144 follows the cam 66.

  The hammer row 18, on which the hood assembly 78 and the cam follower assembly 68 are mounted, is mounted, together with the platen assembly 80, to the base 26 of the shuttle, the shuttle which is shown in detail in Figure 5. The base 26 of the shuttle is of an elongate configuration, generally rectangular, between its ends 30 and 34 of left and right. As indicated above with reference to FIGS. 1 and 2, the left end 30 comprises the tab 28 through which the opening 32 is intended to receive the screw 36. The right end 34 of the base 26 of the shuttle comprises two spaced tabs 164 and 166 traversed by apertures 168 and 170 for receiving screws 40 and 42 shown

in Figure 1.

  The base 26 of the shuttle is configured to define bearing blocks 178 and 180 at its ends.

  right and left ends 34 and 30, respectively.

  The bearing block 178 has a recess 182 while the bearing block 180 has a recess 184. The recesses 182 and 184 are designed to receive the bearings

  linear rails mounted in these recesses and which, themselves,

  same, receive the lengths of axes 84 and 86 of the row 18 of hammers. This allows reciprocating the row 18 of hammers along the longitudinal geometric axis of the axis 82, which longitudinal axis extends in the longitudinal direction of the base 26 of the shuttle. The base 26 of the shuttle is also configured to define a bearing surface 186 located in the immediate vicinity and behind the recess 182, and a bearing surface 188 located behind and in close proximity to the recess 184. The bearing surfaces 186 and 188 are designed to receive the pins 108 and 110, respectively, located at the opposite ends of the plate 106. As described in more detail in the aforementioned application N 069 486, the pins 108 and 110 are held in position. placed on the bearing surfaces 186 and 188 by clamping assemblies 190 and 192 which are shown in FIGS. 8 to 11. The clamping assemblies 190 and 192 allow rotation of the pins 108 and 110 thereon to vary the angular orientation of the plate 106. Apertures 194 and 196 located in the base 26 of the shuttle, in the immediate vicinity of the bearing surfaces 186 and 188, receive mechanisms for adjusting the

  lateral positions of the axes 108 and 110.

  The base 26 of the shuttle further comprises a

  anti-rotation block 198 which is part of an anti-rotation assembly

  rotation 200 described in more detail in the aforementioned application N 069 486. The anti-rotation assembly 200, which is shown in a relatively detailed manner in the sectional view of FIG. 13, prevents the rotation of the row 18 of hammers while simultaneously allowing it

  to reciprocate.

  As shown in FIG. 5, the base 26 of the shuttle has a bottom 202 which extends along its length between opposite front and rear walls 204 and 206. The bottom 202 and the front and rear walls 204 and 206 are extend along the length of the base 26 of the shuttle, between the opposite bearing blocks 178 and 180. The anti-rotation block 98 extends outwardly of the front wall 204, at an intermediate portion of the length of the this front wall 204. The bottom 202 is configured to define three different transverse elements 208

  extending between the front and rear walls 204 and 206.

  The transverse elements 208, with the bearing blocks 178 and 180 arranged transversely, divide the length of the bottom 202 into four different compartments 210, 212,

214 and 216.

  Each of the four compartments 210, 212, 214 and 216 of the base 26 of the shuttle has an opening 218 therethrough. This is also shown in FIG. 12 which is a bottom view of the completed shuttle assembly 10. The four different openings 218, which are spaced from one another and which form an elongated aperture configuration, align with the openings 76 of the base support member 14 so

  to receive pressurized air introduced into the openings

  76. The pressurized air admitted through apertures 218 in the bottom 202 of shuttle hub 26 enters an elongate cavity extending the length of base 26 of the shuttle over compartments 210. , 212, 214 and 216. As described below, this elongate cavity forms a common collector located at the bottom and rear of the row 18 of hammers when the latter is mounted

in the base 26 of the shuttle.

  Figure 6 is a side view, largely in section, of the base 26 of the shuttle as well as the base support member 14, the air chamber 20 and the conduit 22. As previously described with reference to FIG. 1, the fan 24 delivers the air under pressure into the duct 22 into the interior of the chamber 20. The pressurized air in the air chamber rises through the slot 74 located at the party

  of the latter and enters the four openings.

  different tures 76 of the base support member 14.

  As shown in FIG. 6, the pressurized air introduced into the openings 76 passes therethrough and enters the openings 218 in the bottom 202 of the base 26 of the shuttle. The pressurized air from the openings 218 enters the compartments 210, 212, 214 and 216 of the base 26 where it enters the common collector located

  at the bottom of the row 18 of hammers as described below.

  The interface between the horizontal upper surface 44 of the base support member 14 and the bottom 202 of the base 26 of the shuttle is sealed by a piece of sealing tape 220 shown in FIG. 1 so

than the figure 6.

  Figures 7 to 13 show various views

  different from the shuttle assembly 10 in the completed state.

  The shaft length 94 at one end of the hammer row 18 is slidably journalled in a linear slide bearing 222 mounted on the recess 182 of the bearing block 178. A bearing cap 224 is disposed on the linear slide bearing 222. to fix the latter inside the recess 182. Similarly, the axis length 86 at the other end of the row 18 of hammers slidably slides in a linear sliding bearing 226 mounted to the Inside the recess 184 of the bearing block 180. A bearing cap 228 attached to the block 180 holds the linear slide bearing 226 in the recess 184. The details of the linear slide bearings 222 and 226 and the manner in which they are adjusted are described in the aforementioned application No. 069 486. As previously described with reference to FIG. 3, various hammer springs 116 are selectively released by the excitation of the associated coil assemblies 134. Lead wires 230 for one of the

  coil assemblies 134 are shown in FIG.

  The various coil assemblies 134 for the 66 different hammer springs 116 are connected to a control circuit outside the shuttle assembly 10. This connection is made by a number of conducting wires such as the wires 230 which are organized in six buses. wired 232 different along the length of the row 118 of hammers. The wired buses 232, which are better represented in FIGS. 7 and 8, and which rise from the coil assemblies 134, are clamped in position along the opposite side of the hammer row 18 by bars 234 and 236. clamping. The wired buses 232, which are shown cut just below the clamping bars 234 and 236 in FIGS. 7 and 8, terminate in connectors which are coupled with complementary connectors inside the printer 12 to establish the connection of the connectors. coil assemblies 134 with the control circuit after the installation of the shuttle assembly 10 into

the printer 12.

  Figure 13 shows in detail the anti-

  rotation 200 which is described in more detail in the aforementioned application N 069 486. The anti-rotation assembly 200 prevents the row 18 of hammers from rotating by enclosing, by allowing it to slide, the opposite faces of a metal plate 238 mounted on the rear face of the row 18 of hammers, in a central portion of this row 18, so as to prevent the rotation of the row 18 of hammers around the longitudinal axis of the axis 82 while simultaneously allowing a sliding movement of

  the metal plate 238 with respect to this anti-assembly

  rotation so that the row 18 of hammers can perform a reciprocating motion. A slider 240 of globally hemispherical shape slidably bears against one face of the metal plate 238, while an anti-recoil pad 242, fastened to one end of a spring loaded anti-recoil slider 244, slides against the opposite side of the

metal plate 238.

  The platen assembly 80 includes a platinum handle 246. This handle 246 is connected to the axis 108 located at one end of the plate 106 by an arrangement which comprises an adjustable ring 248 mounted on the axis. As described in detail in the aforementioned application N 069 486, the ring 248 of the axis is used to adjust the angular orientation of the handle 246 of the plate relative to the

platinum 106.

  Figure 12 is a bottom view of the shuttle assembly 10, showing the bottom 202 of the base 26 of the shuttle. As shown in FIG. 12, the bottom 202 has the four pressurized air intake openings 218 in the shuttle assembly 10 from the air chamber 20 through the support member 14. 'base. The bottom 202 of the base 26 of the shuttle

  also comprises a sleeve 250 arranged in the

  right end 34 of this bottom, between and in the immediate vicinity of the legs 164 and 166. The sleeve 250 has an opening 252 sized to closely receive the pin 42 which is mounted on the upper surface

  horizontal 44 of the element 14 support base.

  As previously described with reference to FIG. 3 which shows a front portion 253 of the hammer row 18, the front portion 253 has the mounting surface 116 of the hammer spring 116 and the groove 130 for mounting the various pole pieces 126 and 128 and permanent magnets 132 in this groove. Figure 3 also illustrates the lower surface 254 of the hammer row 18. FIG. 4 shows the lower surface 254 of the hammer row 18 and the part thereof opposite the front portion 253 of the row 18 shown in FIG. 3. As shown in FIG. 4, the row 18 of hammers has a rear surface 256 which joins the lower surface 254 via an oblique and lower surface 258. The integrated axis 282 extends through the interior of the hammer row 18 along a portion bottom of this row 18, at a location just above the lower surface 254 and midway between the rear surface 256 and the opposite front portion 253 of the row 18. The latter is mounted within the interior base 26 of the shuttle by positioning axis lengths 84 and 86, located at opposite ends of the hammer row 18, in the linear sliding bearings 222 and 226 which are mounted in the recesses 182 and 184 in the blocks. of p Steps 178 and 180 of the shuttle base 26 as previously described. Figure 13 shows the row 18 of hammers

  thus mounted in the base 26 of the shuttle.

  As indicated previously with reference to FIG. 5, the bottom 202 of the base 26 of the shuttle extends along the length thereof between the front and rear walls 204 and 206. The bottom 202, the front wall 204 and the rear wall 206 of the base 26 of the shuttle are shown in Fig. 13 as well as in Fig. 15 which is a sectional view of the shuttle assembly 10 without the row 18 of hammers. Figure 15 illustrates a shuttle envelope 260 which is connected to the front wall 204 so as to extend along the length of the shuttle base 26 between the opposed bearing blocks 178 and 180. The shuttle envelope 260 is also shown in Figure 13, but is partially hidden from the anti-rotation assembly which is at the very center of the base 26 of the shuttle. The shuttle assembly 260 forms, with the front wall 204 and the bottom 202 of the base 26 of the shuttle, a tight airtight hermetic enclosure extending along the length of the row 18 of hammers, d an area below the bottom surface 254 of the row

  18 of hammers, along the back surface 256 of that

  ci up to an upper portion 261 of this row 18. An airtight seal between the upper portion 261 of the row 18 of hammers and the envelope 260 of the shuttle is formed by a strip formed of a film 262 of polyester affixed sealingly to the inner face of a lip 264 at the upper end of the shuttle jacket 260 by a double-sided tape strip 266. The tape 262 and the double-sided tape 266, which the 15, extend over the entire length of the envelope 260 of the shuttle, between the opposite bearing blocks 178 and 180 of the base 26. During the reciprocating movements of the row 18 of hammers to inside the base 26 of the shuttle, the band 262, which is flexible and resilient, bears against the upper portion 261 of the row 18 of hammers to maintain a generally airtight seal therewith. As shown in Figure 13, a small opening 268 exists between the rear wall 206 of the base 26 of the shuttle and the row 18 of hammers along the length of the latter. The opening 268 is provided by an airtight seal formed by a strip of foam tape 270. The foam tape 270, which is mounted on the top of the back wall 206 along its length, extends to to contact a small portion of the lower surface 254 of the hammer row 18, to

  immediate proximity of the front portion 253 of the row 18.

  While the hammer row 18 is reciprocating within the base 26 of the shuttle, the foam tape 270, which is flexible and resilient, holds the airtight seal between the rear wall

  206 of the base 26 and the row 18 of hammers.

  It can thus be seen that the row 18 of hammers is located inside an elongate cavity 272 located in

  the base 26 of the shuttle assembly 10. The upper portion

  The elongated cavity 272 is closed by the shuttle envelope 260 and sealing is provided by the film web 262. The opposite lower portion of the elongated cavity 272 is sealed by the foam tape 270. The opposite ends of the elongate cavity 272, within and in close proximity to the opposed bearing blocks 178 and 180 of the base 26 of shuttle,

  are hermetically sealed by two

  Opposite cheetah, one of which is shown in Figure 15.

  As shown in FIG. 15, a bottom seal 274 is mounted inside the base 26 of

  the shuttle by means of two screws 276 and washers 278.

  The screws 276- pass through the bottom 202 of the base 26 of the shuttle and penetrate into the lower seal seal 274 to secure it in place. The lower seal 274 extends across the bottom 202 and between the front and rear walls 204 and 206 and has an upper surface 280 configured to mate with the lower portion of the hammer row 18. at one end of this row 18. The seal

  extreme lower 274 sealing forms a global joint-

  airtight with one end of the row 18 of hammers, at one end of the elongate cavity 272. A second lower seal extreme seal, of the same configuration as the lower extreme seal 274, is mounted in the base 26 of the shuttle, at its opposite end, so as to mate with the other end of the row 18 of hammers and to seal this end

of the elongated cavity 272.

  It has previously been noted that the fan 24 delivers pressurized air through the duct 22 into the air chamber 20 where the pressurized air passes through the openings 76 of the base support member 14 and into openings 218 of the bottom 202 of the base 26 of the shuttle. By passing through the openings 218 of the bottom 202 of the base 26 of the shuttle, the pressurized air enters the elongate cavity 272. The row 18 of hammers has several openings which suck air under pressure from the elongated cavity 272 through the interior of the hammer row 18 to an area outside the hammer row 18 below the coil assemblies 134. The air enters the area below the coil assemblies 134 with increased speed and

  significant turbulence. This improves the cooling action

  the turbulent air at high speed on the coil assemblies 134, allowing a cooling action of a large effect in the confined space

  adjacent to the coil assemblies 134.

  The various openings in the hammer row 18 comprise a first group of openings 282 and a second group of openings 284. The openings 282 of the first group are shown in FIG. 3 as well as in FIG. 282 of the first group, which openings are spaced approximately evenly along the length of the row 18 of hammers,

  extends approximately vertically between the surface

  The apertures 284 of the second group extend approximately horizontally in the row 18 of hammers from the rear surface 256, 254 of the hammer row 18 and a generally horizontal surface 286 located at the bottom of a first manifold 288. as shown in Fig. 4. As with the openings 282 of the first group, the openings 284 of the second group are also spaced approximately evenly along the length of the row 18 of hammers. As best seen in FIG. 13, each of the openings 284 of the second group extends from the rear surface 256 through a rear wall 290 of the hammer row 18 to a second manifold 292 formed by a inner cavity extending along the length of the row 18 of hammers. The openings 284 continue horizontally from the rear wall 290 through the second manifold 292 and through a wall 294 to a generally vertical surface 296 located at the first

collector 288.

  Fig. 14 shows a small portion of the first manifold 288 including the horizontal surface 286 and the vertical surface 296 which intersect at the bottom of the first manifold 288. Fig. 14 shows four of the first group openings 282 which are arranged approximately vertically and which lead to the horizontal surface 286. Figure 14 also shows four of the

  openings 284 of the second group which extend horizontally

  The apertures 282 and 284 of the first and second groups have positions alternating along the length of the first manifold 288 so as to be offset from one another to the vertical surface 296. As shown in FIG. on the length of

the row 18 of hammers.

  As shown in FIG. 13, the elongated cavity 272 between the hammer row 18 and the shuttle base 26 forms an air manifold which is common to the first group of openings 282 and the second group of openings. 284. In the present example, air is introduced into the common manifold formed by the elongate cavity 272 at a pressure of about 448 Pa. This produces an airflow of a flow rate of about 850 dm3 per minute. in the common manifold and through the openings 282 and 284 of the row 18 of hammers. As indicated by arrows in FIG. 13, the pressurized air entering the common manifold formed by the cavity 272 splits, a portion of the air entering the first group of openings 282 and the remaining portion of

  the air entering the second group of openings 284.

  The air entering the first group of apertures 282 rises through them and exits at the horizontal surface 286 as shown in Fig. 14. The air entering the second group of apertures 284 flows to through the rear wall 290 and into the second manifold 292. From the second manifold 292, the air flows through the extension of the second group of openings 284 in the wall 294. This air then leaves the openings 284 of the second group, on the vertical surface

* 296 as shown in Figure 14.

  The configuration of the first and second groups of openings 282 and 284 increases the speed of the air under pressure as it passes the common collector formed by the

  cavity 272 in the first manifold 288. This configuration

  It also associates the shifting of the two sets of apertures 282 and 284 to cause significant turbulence in the air entering the first manifold 288. As shown in FIG. 14, the air from the second group of apertures 284, which is introduced horizontally into the first manifold 288 after swirling around the second manifold 292, mixing with the offset vertical air jets from the first group of openings 282 in a highly turbulent manner. As a result, the first manifold 288 is filled with very turbulent air moving at a high speed, and this has been shown to improve

  noticeably the cooling effect of the air.

  The turbulent, high velocity air within the first manifold 288 rises to the coil assemblies 134 where it passes around the first and second magnetic coils 136 and 138 of each assembly 134 and over them. coils. Despite the relatively narrow spacing of the coil assemblies 134 and the large amount of heat they generate, the turbulent, high velocity air within the first manifold 288 appeared to cool more than conveniently. coil assemblies 134 without the need for finned structures or other devices

bulky.

  The first manifold 288, whose horizontal surface 286 is located at the bottom, is bounded on one side by the vertical surface 296. The side of the first manifold 288 opposite to the vertical surface 296 is partly made up of the free upper ends of the springs. hammers 116 in the region of the coil assemblies 134 o the free upper ends of the hammer springs 116 are normally in the retracted position against the pole pieces 126 and 128. The hammer springs 116 are spaced apart by

  relatively small spaces. To prevent turkish air

  bulent, at high speed, in the first manifold 288 to escape through the spaces between the hammer springs 116 instead of passing over the coil assemblies 134, a dam to

2 6 1 8 1.00

  air is formed. The dam is formed by large cheeks located on the nuclei carrying the first and second

  magnetic coils 136 and 138 of the coil assemblies 134.

  This is best shown in FIGS. 20 and 21 which show one of the coil assemblies 134. As shown in FIGS. 20 and 21, the coil assembly 134 includes the first and second magnetic coils 136 and 138 mounted together. The assembly 298 comprises a base 300 which is mounted on the row 18 of hammers, immediately outside the groove 130. The core assembly 298 comprises first and second cores 302 and 304 of coils which are extend outwardly of the base 300 and which respectively carry the first and second magnetic coils 136 and 138. The cores 302 and 304 have hollow interiors configured to receive the front portions of the pole pieces 126 and 128. first core 302 leads to a cheek 306, located at its outer end, adjacent to the end of the first pole piece 126. Similarly, the second core 304 leads to a cheek 308 located at s on the outside end

  adjacent to the end of the second pole piece 128.

  The cheeks 306 and 308 of the cores are arranged to be closely juxtaposed as shown by a small interface 310 therebetween. In addition, because of the relatively narrow spacing of pairs of pole pieces 126 and 128 along the length of groove 130, their core assemblies 298 are relatively close together so that their cheeks 306 and 308 are closely juxtaposed. with the cheeks 306 and 308 of

  adjacent core assemblies 298 on opposite sides thereof.

  Therefore, besides that the cheeks 306 and 308 of each core set 298 combine to form a nearly continuous wall at the outer ends of the coils

  magnetic strips 136 and 138, the cheeks 306 located in the

  outer trenches of the various pole pieces 126 form an almost continuous wall along the length of the

  130 at the outer ends of the magnet coils

  136. Similarly, the flanges 308 at the outer ends of the pole pieces 128 form an almost continuous wall along the length of the groove 130 at the outer ends of the magnetic coils 138. The wall or air barrier thus formed is opposed by highly efficient way to exhaust large quantities of turbulent air, at high speed, in the first manifold 288 through the spaces between the springs of

  adjacent hammers- 116. The air barrier requires

  all of the air to be passed over the magnetic coils 136 and 138 of each of the coil assemblies 134. Then the air is directed directly upwardly and outwardly of the shuttle assembly 10, as indicated

  by arrows at the top of Figure 13.

  As shown in FIG. 13, row 18 of

  hammers consists of two elongated elongated elements

  The first elongated member 312 forms the front portion 253 of the hammer row 18. The lower part of the elongated element 312 forms the mounting surface 118 of the hammer springs and the first manifold 288. The opposite upper part of the first elongate element 312 has the groove 130 for receiving the pole pieces 126 and 128 and the magnets permanent 132 and ends with the upper portion 261 of the row 18 of hammers. A portion of the bottom portion of the elongate member 312, opposite the hammer spring mounting surface 118, is configured to receive a circumferential portion of the axis 82 along its length. The second elongate member 314 is connected to the first elongated member 312 at its lower and upper portions. The lower portion of the second elongated member 314 forms a substantial portion of the lower surface 254 as well as the entire upper surface 256 and the oblique lower surface 258 of the row 18 of hammers. The lower portion of the second elongate member 314 is configured to receive a circumferential portion of the axis 82 along its length. A portion of the second elongate member 314 is spaced from the first elongated member 312 to form the second manifold 292 with the first elongated member 312, at a circumferential portion of

the axis 82.

  As indicated above, each of the hammer springs 116 is retained in the retracted position against an associated magnetic hammer actuator from which it is selectively released or tripped, this actuator comprising the two pole pieces 126 and 128, the permanent magnet 132 and the assembly 134 comprising the first and second magnetic coils 136 and 138. Despite the immediate proximity of the adjacent magnetic hammer actuators, due to the compact configuration of the hammer row 18, the magnetic interaction between these actuators is significantly minimized by a certain number of hammers. of features of the row 18 of hammers. One of these features is that with the exception of the permanent magnet 132, no magnetic material extends between two or more magnetic actuators and is therefore not common to these actuators. The elongated element 312 of the hammer row 18, which has the groove 130, is made of a non-magnetic material, namely aluminum in the present example. The second elongate element 314 of the hammer row 18 is also made of aluminum, as is the axis 82. The only magnetic element extending between adjacent magnetic actuators is the permanent magnet 132 which passes only no flow of

  leakage between adjacent magnetic actuators of hammers.

2618-100

  In the present example, a different permanent magnet 132 is associated with each different group of four magnetic hammer actuators. The various permanent magnets 132 are arranged end to end to form a generally continuous structure of permanent magnets along the length of the groove 130. FIG. 16 shows one of the permanent magnets 132 as well as the pole pieces of the four magnetic actuators of FIG. hammers that

  are associated with it. The permanent magnet 132 is of

  elongated figuration, generally rectangular, and is disposed between the rear portions 316 and 318 of each pair of pole pieces 126 and 128. The rear portions 316 and 318 of the pole pieces 126 and 128 and the permanent magnet 132 which is arranged between them are mounted in the groove 130 by means of an epoxy resin or other suitable non-magnetic adhesive. Each pair of pole pieces 126 and 128 has front portions 320 and 322 that extend outwardly of the groove 130 and receive the magnetic coils 136 and 138 of a set.

  different I34 to coils, as previously described. -

  Figure 17 is a front view of the permanent magnet and four pairs of pole pieces 126 and 128 associated therewith. It is very advantageous for the permanent magnet 132 to extend through the space included

  between each adjacent pair of pole pieces 126 and 128.

  In the absence of the permanent magnet 132 between adjacent pairs of pole pieces, a large leakage flux has appeared between the upper pole pieces 126 and the lower pole pieces 128. With the permanent magnet 132 extending through the spaces between the adjacent pairs of pole pieces 126 and 128 and therefore present in these spaces, however, it has been found that the leakage flux between the upper pole pieces 126 and the lower pole pieces 128 is significantly minimized. As shown in FIG. 17, the lines representing the magnetic flux extend from the first and second pole pieces 126 and 128 to the permanent magnet

Where they end.

  By using only non-magnetic materials between the various magnetic hammer actuators, with the exception of the permanent magnets 132, and extending the permanent magnets 132 between the adjacent pairs of pole pieces in the various magnetic actuators different from hammers, it appeared that unwanted magnetic interaction between actuators

  Magnetic adjoining hammers is notably

  bet. In this example, it appeared that this interaction was lowered to a level as low as

part for 10,000 or even less.

  Fig. 18 is a sectional view of a portion of the hammer row 18 showing the hammer spring mounting surface 118 and a hammer spring 116, the screw 120 and the mounting plate 122. As previously described with respect to FIG. 3, the lower end of each hammer spring 116 is attached to the mounting surface 118 by a different screw 120 which passes through the mounting plate 122 and through the lower end of the hammer spring 116 which enters the row 18 of hammers. A different mounting plate 122 is used for mounting each

pair of springs 116 of hammers.

  The hammer spring 116 mounting screw 120 enters a screw hole 324 in the hammer row 18 as shown in Fig. 18. The screw hole 324, which has an end at the mounting surface 118, is opening, because its opposite end opens into one of the openings 282 of the first group of the row 18 of hammers. Row 18 has 66 screw holes 324 spaced along its length at the hammer spring mounting surface 118 for mounting the 66 hammer springs 116. The number of first group openings 282 spaced along the length of the row 18 hammers is enough for each screw hole 324

  leads to one of the openings 282 of the first group.

  The screw holes 324 of the hammer row 18 have several advantages. On the one hand, the screw holes 324 are relatively long in that they extend from the mounting surface 118 of the hammer springs, over the entire length, to one of the openings 282 of the first group . This allows the mounting screws 122 to be relatively long and thus ensure a better and stronger mounting springs 116 of hammers. In addition, the screw 120 can extend completely through the screw hole 324 and enter into one, adjacent, openings 282 of the first group if necessary. The emergent configurations of the screw holes 324 have another advantage in removing dirt and other debris. When the mounting screw

  a hammer is inserted into a screw hole that is not

  edge, lubricant residues and other debris are caught between the end of the screw and the end of the screw hole where debris remains. On the other hand, in the configuration shown in FIG. 18, the open end of the screw hole 324, to one, adjacent, openings 282 of the first group, makes it possible to expel these debris in

the opening 282.

  As previously described with respect to FIG. 3, a plurality of magnetic fastener assemblies 104 are mounted on the hammer row 18 to hold the upper portions of the hood assembly 78 in a fixed position relative to the row 18. One of Magnetic fastener assemblies 104 are shown in detail in Figure 19. As shown, the magnetic fastener assembly 104 has two pins 326 and 328 attached to the upper portion 261 of the hammer row 18, at a different length portion. of the row 18 to protrude outwardly in a generally parallel and spaced disposition. An elongated base clip 330 extends between outer ends 336 and 338 of the pins 326 and 328, respectively, to which the opposite ends 332 and 334 of this clip are attached. Each of the ends 332 and 334 of the base clip 330 partially surrounds an associated one of the outer ends 336 and 338 of the pins 326 and 328 and is attached thereto by welding. A permanent magnet 340 is mounted on an intermediate portion 342 of the base clip 320 between its opposite ends 332 and 334. The permanent magnet 340 is attached to the intermediate portion 342 of the base clip 330 by three different rivets 344. which pass through an upper fastener 346, the magnet

  permanent 340 and the intermediate portion 342.

  After mounting pins 326 and 328 in the upper portion 261 of the hammer bank 18 and assembling the remaining portion of the magnetic attachment assembly 104 as shown, the various magnetic fastener assemblies 104 spaced along the length of the row 18 of hammers, at its upper portion 261, are ground as necessary so that each attachment assembly 104 has a reference surface 348 at a desired position relative to the upper portion 261 of the row 18 of hammers. The reference surface 348, which is formed of the outer ends of the pins 326 and 328, an edge of the base clip 330, a side edge of the permanent magnet 340 and an edge of the clip upper 346, receives the upper edge 102 of the hood assembly 78 and maintains this upper edge 102 in the desired position relative to the row 18 of hammers, this position being defined by the surface of

reference 348.

  In the present example, six sets of magnetic fasteners 104 are spaced along the length of the upper portion 261 of the hammer row 18. One of the magnetic clip assemblies 104 is shown in the cross-sectional view of FIG. 13. Also in the present example, the permanent magnet 340 is made of a magnetizable rubber magnet. After assembly of the magnetic attachment assembly 104 and its grinding, the rubber magnet is magnetized to form the permanent magnet

340.

  It goes without saying that many modifications

  can be made to the printer described and represented

  without departing from the scope of the invention.

Claims (35)

  A printer comprising an elongated frame structure mounted within the printer and having an elongate chamber (272), an elongate row (18) of hammers mounted in the elongated chamber of the frame structure and capable of performing a reciprocating motion, the row of hammers comprising a plurality of magnetic coils (136, 138) mounted along its length, a source (24) of pressurized air and means (20, 22) connecting the source of pressurized air to the chamber extending the frame structure to introduce pressurized air into the chamber, the printer being characterized in that the elongated row of hammers has a plurality of openings (282, 284) for passing air under pressure from of the chamber on the reels, each of the openings having an end located in the chamber and   an opposite end adjacent to the coils.   The printer according to claim 1, characterized in that the openings comprise a first group of openings (282) spaced along the length of the hammer row and extending between a first zone located in the chamber and in the adjacent zone. to the reels, and a second group of openings (284) spaced along the length of the hammer row and extending between a second zone in the chamber and the zone adjacent to the coils.   3. Printer according to claim 2, characterized in that the second group of openings is offset with respect to the first group of openings so that the openings of the second group alternate with those of the second group of openings.   first group along the length of the row of hammers.   4. Printer according to claim 2, characterized in that the chamber defines a common collector for the pressurized air introduced into this chamber by the means connecting the source of pressurized air to the elongated chamber, the area adjacent to the coils defining a first collector (282) and the   row of hammers having an elongated cavity defined   a second collector (292), the second group of openers   tures extending from the common manifold to the first manifold   through the second collector.   5. Printer according to claim 1, characterized in that the elongated frame structure   has an elongate base (26) for the shuttle (10)   an elongate chamber (272) whose bottom (202) has at least one opening (218) extending into the chamber, and the means connecting the pressurized air source to the elongate chamber comprises a member (14) ) of the base bracket on which the base of the shuttle is   mounted and which is traversed by an opening (76) communicating   with respect to the aperture (s) (218) of the bottom of the shuttle base, and means for introducing pressurized air from the pressurized air source into the aperture (s) passing through the support of base.   6. Printer according to claim 5, characterized in that the means for introducing air from the source of pressurized air into the opening or openings through the base support member comprise an air chamber. recess (20) mounted on the bottom of the base support member and whose hollow interior communicates with the opening or openings of the shuttle base, and a conduit (22) connected to the interior of the air chamber, the source of pressurized air comprising a fan (24) connected to the duct.   7. Printer according to claim 5, characterized in that the bottom (202) of the base of the shuttle has a plurality of openings (218) spaced along the length of the base and terminating in different parts of the length of the chamber and the means for introducing pressurized air from the source of pressurized air into the chamber of the shuttle base introduces pressurized air into   each of the openings of the bottom of the base.   8. Printer according to claim 5, characterized in that the chamber extends upwardly above the base of the shuttle and is covered with an elongate envelope (260) of shuttle mounted on the base and extending into an area adjacent to a   upper part (261) of the row of hammers.   The printer of claim 8, further characterized by an elongated strip (262) of flexible material connected to the shuttle envelope, along the length of said envelope and extending to enter   contact with the upper part of the row of hammers.   The printer of claim 5, further characterized by two extreme sealing seals (274) mounted in the chamber and each extending to contact with a different one of the opposite ends of the hammers for sealing the chamber at opposite ends of the row of hammers. 11. Printer according to claim 10, characterized in that the base of the shuttle forms an opening (268) in the chamber with a lower part of the row of hammers, along the length of the chamber, and in that a band (270) of flexible material is mounted on the base of the shuttle over the length of the chamber and extends to contact the lower portion (254) of the row of hammers to close watertight the opening in the room.   12. The printer according to claim 1, characterized in that the elongated row of hammers comprises several hammer springs (116) mounted along the length of the row, at the bases of the hammer springs, length of the row, at the bases of the springs of hammers, and having opposite upper ends, the row of hammers having a recessed portion (130) extending along its length, adjacent to the upper ends of the hammer springs, the magnetic coil assemblies (134) being mounted on the row of hammers, along its length, and extending to the upper ends of the hammer springs within the recessed portion of the row of hammers, the latter having a plurality of openings (282) spaced along its length and extending each through the row of hammers, a   lower zone of the row to the recessed part,   below the coil assemblies, in order to conduct pressurized cooling air, introduced into the lower zone of the row of hammers, up to the portion   hollowed out below the coil assemblies.   13. The printer as claimed in claim 12, characterized in that each of the magnetic coil assemblies comprises at least one coil (136 or 138) extending from the row of hammers in the recessed portion and ending in a cheek (306, 308) at its outer end, adjacent to the upper ends of the hammer springs, the core cheeks of the magnetic coil assemblies forming an air barrier in the region of the upper ends of the coil springs. hammers.   14. Printer according to claim 12, characterized in that the openings comprise a first group of openings (282) spaced along the length   of the row of hammers and extending almost vertically   between the lower zone of the row of hammers and the recessed portion of the row of hammers, and a second group of openings (284) spaced along the length of the row of hammers and extending approximately horizontally between a portion superior of the lower zone of the   row of hammers and the recessed portion of this row.   15. The printer as claimed in claim 14, characterized in that the row of hammers has a plurality of screw holes (324) each extending between an outer surface (118) of the hammer row and one of the openings (282) of the hammer row. first group, and each receiving a screw (120) for mounting one of the springs of hammers on the row.   The printer according to claim 14, characterized in that the recessed portion of the hammer bank has a generally horizontal surface at its bottom, to which the openings of the first group terminate, and a generally vertical and contiguous surface to which the openings of the second group. 17. Printer according to claim 14, characterized in that the openings of the first and second groups alternate along the length of the row of hammers.   in order to be offset from each other.   The printer according to claim 14, characterized in that the hammer bank has an elongate chamber (292) extending along the length of that row and disposed between the upper portion of the lower zone of the hammer row and the portion recess, each of the openings of the second group extending from the upper part of the lower zone of the row of hammers to the recessed portion through the elongate chamber. 19. A row of hammers for use in a printer, comprising an elongated nonmagnetic material frame, a plurality of hammer springs (116) mounted along the length of the elongate housing, by first ends of said springs opposing second free ends of said springs. , and a plurality of pairs of pole pieces (126, 128) mounted along the length of the elongate frame, each pair of pole pieces being adjacent to the second free end of a different one, hammer springs and at least one pole piece of each pair carrying a coil (136 or 138), the row of hammers being characterized in that it comprises an elongate, generally continuous structure of permanent magnets (132) extending along the length of the frame and arranged between the pieces poles of the group formed by pairs of pole pieces, the generally continuous structure of permanent magnets minimizing parasitic flux between the pieces polar of each pair.   20. row of hammers according to claim 19, characterized in that the generally continuous structure of permanent magnets consists of several permanent magnets (132) mounted end to end and each arranged between the pole pieces of each different, pairs of pole pieces, the pole pieces of each pair having rear ends disposed on opposite sides of one of the permanent magnets and opposite front ends extending to contact the second free end of one of the springs of hammers, coils (136, 138) being mounted on the front ends.   21. row of hammers according to claim, characterized in that the pairs of pole pieces of each different, pairs of pole pieces are spaced from each other along the length of the frame   lengthened and include one of the permanent magnets   part of the length of the elongate frame between the opposite pole pieces of each pair and between   spaced pairs of polar pieces.   22. Row of hammers according to claim 19, characterized in that the elongated non-magnetic material frame has, at its base, a surface (118) for mounting hammer springs extending along the length of the frame and a groove ( 130) extending over the length of the frame and spaced from the hammer spring mounting surface, the hammer springs being disposed in a generally parallel arrangement and spaced apart along the length of the frame and being each connected at its first end to the hammer spring mounting surface, the second free and opposite end of each hammer spring being adjacent to the groove, the pole pieces of each pair being mounted in the groove in close proximity to the second end of the one, different , hammer springs, several pairs of coils (136, 138) being each mounted on the pole pieces of a different pair of pole pieces outside the pole. groove, and the elongate, generally continuous structure of permanent magnets being disposed within the throat.   23. Row of hammers according to claim 22, characterized in that the generally continuous structure of permanent magnets comprises several elongate permanent magnets (132) arranged generally end to end inside the throat.   24. A row of hammers according to claim 23, characterized in that the frame is elongated in the direction of its length, each of the pole pieces is of elongated configuration, generally rectangular, and extends in a substantially perpendicular direction. to the elongation direction, and each of the permanent magnets   is of elongated configuration, generally   gular, and extends in the direction of elongation.   25. Row of hammers according to claim 23, characterized in that each of the elongated permanent magnets is disposed between the opposite pole pieces of four pairs of polar pieces.   26. Row of hammers to be used in a   printer, comprising an elongated frame, a plurality of   Magnetic hammer drums mounted on the frame along the length thereof and each associated with one, different, of several hammer springs (116), the row of hammers being characterized in that it comprises a single axis, hollow (82), made in one piece, mounted in the frame and extending along the length of said frame of opposite ends from which it projects outwardly for mounting the row of hammers so that it can reciprocate.   27. Row of hammers according to claim 26, characterized in that the axis is cylindrical hollow in cross section.   A row of hammers for use in a printer, comprising an elongated housing having a hammer spring mounting surface (118) extending over the length of the housing, and a plurality of hammer springs (116) mounted on the frame, along the mounting surface, the row of hammers being characterized in that the frame has a plurality of openings (282) spaced along its length, and a plurality of screw holes (324) also spaced along its length and extending each between the mounting surface of the hammer springs and one of the apertures, each of the hammer springs being mounted by means of a screw (120) passing through the hammer spring and penetrating into a different one, screw holes. 29. Row of hammers according to claim 28, characterized in that the openings are arranged in a generally vertical manner and have the effect of drawing air under pressure from the outside of the frame through them. to an opposite area of the building.   30. An assembly formed by an elongate row (18) of hammers, mounted to be reciprocated, and a bonnet assembly (78) mounted on the hammer row adjacent a platen (106) in a printer (12), characterized in that it comprises a plurality of magnetic fastener assemblies (104) mounted on the hammer bank and holding the hood assembly thereon, each of the magnetic fastener assemblies extending outwardly of the row of hammers and comprising a permanent magnet (340) mounted on this assembly and now on the latter a portion of   the hood assembly, by magnetic attraction.   An assembly according to claim 30, characterized in that each of the magnetic fastener assemblies has two pins (326, 328) attached to the hammer row and projecting outwardly, a base clip (320) extending between the two pins and secured by its opposite ends (332, 334) to said pins, and a permanent magnet (340) mounted on the base clip, at a portion thereof lying between its opposite ends.   32. The assembly of claim 31, characterized in that each of the opposite ends of the base clip is wound around a portion of one two pins and is soldered to it.   An assembly according to claim 31, further characterized by an upper fastener (346) disposed against the permanent magnet, on the opposite side to that of the base fastener, and by a plurality of rivets (344) securing the upper fastener and the permanent magnet to the attachment of base and crossing them.   34. A row of hammers in which cooling air is introduced into an area adjacent to a plurality of coils (136, 138) connected to the row of hammers, the area extending between the row (18) of hammers and several springs (116) hammers mounted on the row and adjacent the reels, the hammer row being characterized by a plurality of cheeks (306, 308) of coils (302, 304) of coils at the ends of the coils adjacent to the hammer springs, the cheeks coils extending outwardly from the coils and being closely juxtaposed to each other to form an air barrier for the cooling air passing between the hammer springs and the hammer row, and the coils. -   35. Row of hammers according to claim 34, characterized in that the coils are mounted on   polar pieces (126, 128) which project towards the former   the interior of the hammer row, in pairs, and which are spaced from adjacent pairs of pole pieces along the length of the row of hammers-so as to form first and second rows of pole pieces spaced along the length of the row of hammers and on which first and second rows of reels (136, 138) are mounted, the core cheeks of each of the first and second row reels extending so as to be closely juxtaposed to adjacent reed cheeks on opposite sides said cheeks in the same row and be closely juxtaposed to opposite coil cheeks in the other row.