Patent Publication Number: US-3874287-A

Title: Printing machines

Description:
United States Patent [191 Aldea [451 Apr. 1,1975  
 [ 4] PRINTING MACHINES [75] Inventor: Jacques Aldea, Danjoutin, France [73] Assignee: Societe HoneywellBull (Societe Anonyme), Paris, France [22] Filed; June 5, 1973 [21] Appl. No.: 367,253  
 [52] US. Cl. fill/93.48 [51] Int. Cl B4lj 9/42 [58] Field of Search 101/93 C, 111  
 [56] References Cited UNITED STATES PATENTS 3,155,033 11/1964 Nelson et a1. 101/93 C 3.228.325 H1966 Miller 101/93 C 3,359,921 12/1967 Arnold ct a1... 101/93 C 3,630,142 12/1971 Fu1ks ct a1. 101/93 C 3,636,868 1/1972 Johnston et a1 lOl/93 C 3.673.955 7/1972 Curtiss et al. 101/93 C Primary Examiner-Edgar S. Burr Assistant Examiner-Edward M. Coven Attorney, Agent, or Firm-Fred Jacob [57] ABSTRACT A printing machine is provided comprising a character support that passes in front of a print medium, a striking block with N striking elements which each include a print hammer, elastic means for supplying the striking force for the hammer, a device which keeps the hammer under tension and releases it at the instant of the strike, means for arming the hammer and means for damping the hammer. The damping means comprises N tongues each disposed on a support coated witha layer of material having a strong damping power, each tongue being associated with a striking element.  
 15 Claims, 6 Drawing Figures PATENTEUAPR 1191s 3, 874,287  
 sum 2 OF 3 FIGZ b SEiZET 3 OF 3 PATENTEU APR 1 W5 YFIGJb PRINTING MACHINES BACKGROUND OF THE INVENTION The present invention concerns high speed printing machines and deals in particular with a system of dampers for printing hammers.  
  Modern high speed printers include a print medium before which a character support passes which is subject to a periodical movement such that each printable character is offered at each print position of a print line. With the agreement of each print position of a line, a striking means which releases a print hammer at the desired moment, i.e., when the character to be printed happens to be in the corresponding printing position.  
  For various reasons, varying from printer to printer, the return movement of the hammers after a strike must be rapidly clamped by dampers (for example, in certain printers the movement of the hammers must be capable of being performed with precision in a matter of milliseconds; in other printers, the stepping movement of the print medium can only be initiated when the movement of the hammers is completely stopped, etc.). However, since the printing hammers must have a sufficiently high force to accomplish uniform printing for several copies and since, consequently, their return energy after a strike is not negligible, damping of the hammers must be efficient.  
  As far as the printers with mechanical release are more particularly concerned, it is known that the tension of their hammers must be renewed after each printing of a printing line. It may be observed then, that for these printers, the operations of restoring the tension of the hammers and of the dampers must be closely coordinated, in fact, they must be simultaneous.  
  Certain printers with mechanical release meet these requirements. In these, the striking means use potential energy, stored in the form of elastic energy by springs for setting in motion of the printing hammers, and in clude a magnet, which must be a permanent magnet or an electromagnet, which holds the printing hammer under tension, the spring blades which function as support for the printing hammers being tensioned, the elastic energy of the strike being released by suspension of the action of the magnet by a release winding. After the striking of a printing line, the tension of the hammers is renewed (they are again placed under tension against the magnetic yokes of the magnets) by a first system of tension renewal consisting of cams and levers.  
  The printing hammers consist of small flat bars, a section of which is bent functioning as an armature; the latter is intended to be pressed against the magnetic yoke of the magnet.  
  Above each hammer, close to the printing line of the write medium, a damper of plastic material is positioned; it blocks the hammer until the latter is engaged by the magnet.  
  Before a strike occurs, this damper is removed by pivoting during a short period, to release the corresponding hammer by means of a system of cams and levers also functioning as tension renewal of the dampers. The systems of tension renewal of the hammers and that of the dampers act simultaneously.  
  These striking devices involve some drawbacks. On the one hand, the presence of the two systems of tension renewal makes these striking devices more complicated, hence more expensive, and on the other hand,  
 their delicate synchronization and the arrangement of the dampers delays the moment when the printed line can be seen, which makes the eventual control of the printing more difficult.  
 SUMMARY OF THE INVENTION The present invention remedies these drawbacks by arranging the dampers in a simple manner above the magnets for supporting the hammers and by utilizing a system of tension renewal common to hammers and dampers. The printing machine according to the inven tion includes:  
 1,. A character support that passes in front of a print medium;  
 2. A striking block with N striking means of which each includes;  
 a printing hammer,  
 elastic means supplying the striking energy of the hammer,  
 a device that keeps the hammer under tension before each strike and releases it at the moment of the strike;  
 3. Means for imparting tension to the hammers; and  
 4. Damping means for the hammers.  
  The printing machine is characterized in that the damping means consist of N tongues, each placed on a support coated with a layer having a strong shockabsorbing power, in the vicinity of the aforementioned devices, each tongue being associated with a striking means in such a manner that, during the return movement, the hammers act on said tongues so as to dampen the oscillations of the hammers.  
  In a preferred form of design of the invention, the printing machine, moreover, includes mechanical links connecting said support with said arming means in such a manner that the placing of the hammers and of said tongues .under tension be simultaneous. Said elastic means consist of two metallic rods supporting the hammer and being attached to a support block common to all hammers.  
  In a particular form of embodiment of the invention, each magnetic device includes a magnet (either a permanent magnet or an electromagnet) associated with a magnetic circuit comprising two pole pieces against which the hammer is pressed when it is under tension, and a release winding, generating, at the moment of the strike, a magnetic induction field so that the flux in the pole pieces passes through a minimum value, releasing the hammer. The arming means preferably include, on each of the two ends of said support block, two elastic blades and an arm carrying at its end a wheel in contact with a cam. The shock-absorbing tongues are best constructed of a plastic material, and preferably of a rubber material.  
  The means for mechanical linkage comprise on each of the two ends of the striking block a lever in solid connection with the tongue support whose attachment point is fastened on the frame of said machine; this lever is driven by adjustable bushings, by a beam support positioned on the end of the support block of the hammers.  
 I I BRIEF DESCRIPTION OF THE DRAWING- The invention will be better understood during the following description, presented with reference to the attached drawing, which is offered for explanatory, not limiting purposes,a form of embodiment in accordance with the invention. ln the drawing:  
 FIG. 1 is a schematic view in perspective of the printer system with its set of dampers; FIG; 2a is&#39;a cross-sectional view through a damping tongue and its support, and illustrates a layer of low energyrestoring power between damping tongues supported upon a beam.  
  EIG. 2b is a top plan view of the arrangement of FIG. 2a and illustrates a plurality of individual damping tongues. FIG. 3a is a schematic side view of the printer system or printing machine of this invention, and illustrates schematically striking hammers at their point of contact with the dampered tongues after rebounding in a direction away from the printing characters and an associated printing medium.  
  FIG. 3b is a view similar to FIG. 3a, and illustrates the manner in which the printing machine is reset prior to a rearming operation.  
  FIG. 30 is a view similar to FIGS. 3a and 3b, and illustrates the armed condition of the printing machine.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT An example of the printer according to the invention is represented in perspective, in FIG. 1. This printer includes a character support 1 carrying a number N of characters 100, 101, 102, etc... The support shown here is an endless belt carrying type, but it may also be, for example, another linear character support, or a drum. This character support 1 passes before a print medium 2 and a set of striking devices 4. For a better understanding of FIG. 1, only the two end striking devices 4A and 4B are here represented.  
  In the example of embodiment described here, the system consists of 132 or 144 striking devices 4 which are grouped in sub-systems of 8 devices. Each striking device 4 includes (see also FIG. 3) a magnetic holding device generally referred to by the reference numeral 5, which includes individual holding devices 5a and 5b for the devices 4A and 4B, respectively. This device may,&#39;for example, be of that type described in French Pat. No- 1,453,936 and French Pat. application No. 71 07104, filed &#39;on Mar. 2, 1971 for a Striking device for the rapid printing of characters, by the claimant. One, as well as the other, of these devices consists of a magnet (permanent or electromagnet) connected with a magnetic circuit having two pole pieces, against which the hammer is applied when armed, and a release winding, generating at the moment of the strike, a magnetic induction field such that the flux in these pole pieces of said circuit passes through a minimum value, while a hammer 6, 6A and 6B equipped with a protruding part 61, 61A and 61B, functions as a magnetic armature for the holding device 5. This hammer 6 is fastened to a support block or carriage 7 by elastic metallic blades 8 and 9, 8A and 9A, respectively, 88 and 9B for the devices 4A and 4B.  
  Arming means are associated with the set of hammers 6 and include at the two ends of the support block 7 and the system 3 flexible, metallic blades 10A and 11A, 10B and 11B, firmly connected, on the one hand, with the, support block 7, and on the other hand, with the frame of the printer. Thus, one may say that the support block 7 is suspended on the frame of the printer by the blades 10A and 11A, 10B and 118.  
  The ends of the arms 12A and 12B are equipped with wheels 13A and 13B which are in contact with the cams 14A and 14B, respectively, driven in a rotational movement in the direction indicated by the arrows F and F2. 7 v  
  The wheel 13A and 13B are held against the cams 14A and 14B by the effect of the drawsprings 22A and 228.  
  To dampen the oscillation movement of the hammers when they have just struck a character, the printer comprises a set 15 of dampers 16, 16A and 168 for the devices 4A and 4B, respectively. These shockabsorbers 16 are attached to a support beam 17 which covers, as may be seen in FIG. 1, the entire length of the system 3 of the striking devices above the magnetic holding devices 5 of the hammers 6. For convenience of the drawing, the cross-section of the beam 17 is represented rectangular, but obviously the form of this section is so calculated as to support the normal forces exerted by the effect of the hammers on this support by means of the tongues, during their return movement.  
  It should be pointed out that in the case in which the hammers 6 are pressed against their holding devices 5 the assembly 15 is tilted in relation to a direction perpendicular to the surface struck by the characters or, that which turns out to be the same, perpendicular to the striking axis of the hammers.  
  The beam 17 is supported at its ends by two levers 18A and 18B whose attachment points 19A and 19B are located on the frame of the printer. These levers 18A and 18B are driven by means of adjustable bushings 21A and 21B by beam supports 20A and 20B located at the ends of the support block 7 of the hammers 6. Thus, it may be seen that the set 15 of dampers is tied to the means of tension renewal via the levers 18A and 18B, the beam supports 20A and 20B and the bushings 21A and 218.  
  FIG. 2a is a sectional view of a damper 16, and of the support beam 17, and FIG. 2b is a plan view showing a subset of 8 dampers 161 to 168. In the design example described here, each damper 16 has the form of a thin tongue made of plastic material. These tongues rest on the beam 17 through the intermediary of a layer 23 of rubber of any other material that has a low energy-restoring power. This layer 23 very significantly reinforces the damping power of the tongues 16. The layer 23 fully, or partially covers the support 17. Each subset of 8 tongues corresponds with a subset of 8 striking devices 4. These subsets are attached to the beam 17 by screws inserted through the holes 24 and 25.  
  The operation of the printer and set of dampers is illustrated in FIG. 3. In that illustration, the printer is shown in side view and any one of the striking devices 4 is represented.  
  The operation is divided essentially into three phases sequentially represented in FIGS. 3a, 3b and 3c and described hereafter.  
  1. Phase 1: FIG. 3a a strike has just occurred (the hammer having been released by the device 5), the hammer 6 is engaged by the damper 16 which contacts the upperpart of the magnetic armature 61 of the hammer 6. The latter rests outside the field of action of the magentic holding devices. The blades 8 and 9 -are roughly straight and the blades 10A and 10B; 11A and 11B are bent. Thewheels 13A and 13B are in contact with the protruding, non-concave parts of the cams 14A and 14B. 7 i v 2. Phase 2: FlG.&#39;3b the cams 14A and 14B revolve in the direction indicated by the arrows F, and F the wheels 13A and 13B come into contact with the latters concave part. The support block 7 is displaced in a parallel direction to the longitudinal axis of the arms 12A and 12B (due to the elasticity of the blades 10A and 10B, 11A and 118) in the direction of the arrow F i From this it follows that the blades 8 and 9 and the hammer 6 also move in that direction; the armature 61 now comes into contact with the magnetic holding device 5 to be held, pressed against it. The damper 16 is no longer in contact with the upper part of the armature 61 and has just occupied a position which is roughly parallel with the longitudinal axis of the arms 12A and 128. The blades 10A and 10B, 11A and 11B are no longer bent, and become straightened. It is clear that the damping of the oscillation movement of the hammers occurs between the phases 1 and 2, after the force of the return movement of the hammer to the holding device 5 has just forcefully pressed the damper 16 against the rubber coating 23 of the beam 17, which at the same time absorbs the said energy.  
  3. Phase 3: H6. the cams 14A and 14B continue revolving in the direction of the arrows F and F the wheels 13A and 13B are again at the protuding, nonconcave part ofthe cams. The support block 7, thereafter, moves in the direction of thearrow F Since the armature 61 remains attracted by the magnetic holding device 5, the blades 8 and 9, 10A and 10B, 11A and 118, as a result, bend anew. The damper 16 comes to rest on the armature 61 and bends slightly. The blades 8 and 9 store a certain elastic energy. The hammer 6 is again ready to strike.  
 What is claimed is:  
  1. A printing machine comprising a character support carrying a number of printing characters and a plurality of striking hammers between which is adapted to pass a printing medium. means for resiliently mounting said striking hammers for movement toward and away from said printing characters, means for deflecting said resilient mounting means for arming said striking hammers for movement toward said printing characters, means for selectively holding and releasing said armed striking hammers whereby upon the release thereof said striking hammers move toward said printing characters and rebound therefrom, means for damping said striking hammers during the rebound movement thereof in a direction away from said printing characters, said damping means being supported by a beam spanning said striking hammers, said damping means being defined by a plurality of tongues each tongue being associated with one of said striking hammers, said arming means including a carriage carrying said resilient mounting means, said arming means further including means for moving said carriage toward said printing characters for deflecting said resilient mounting means whereby said striking hammers are armed. and means responsive to said last-mentioned movement of said carriage for moving said beam and the damping tongues carried thereby toward said striking hammers generally simultaneously with the move ment of said carriage toward said printing characters therebyto position said tongues to intercept the striking hammers duringthe rebound movement thereof.  
  [2. The printing machine as defined in claim 1 wherein said damping means includes a layer of high damping power material sandwiched between said beam andsaid tongues. i  
  3. The printing machine as defined: in claim 1 wherein said tongues are constructed from high damping power materiaL- I 4. The printing machine as defined in claim 1 including means for mounting said beam for pivotal motion toward and away from said striking hammers, and said responsive means includes connection means between said beam mounting means and said carriage whereby said beam and the damping tongues carried thereby are moved generally simultaneously with the movement of said carriage.  
  5. The printing machine as defined in claim 1 including means for resiliently biasing said carriage for movement in a direction away from said striking hammers whereby return movement of said carriage away from said printing characters after a printing operation is achieved under the influence of said biasing means.  
  6. The printing machine :as defined in claim 1 wherein said beam and the damping tongues carried thereby are disposed a predetermined distance from said printing characters in the armed condition of said striking hammers with said damping tongues each being in overlying deflected engagement with an associated striking hammer.  
  7. The printing machine as defined in claim 1 wherein said beam and the damping tongues carried thereby are disposed a predetermined distance from said printing characters in the armed condition of said striking hammers with said damping tongues each being in overlying deflected engagement with an associated striking hammer, and said beam and damping tongues are disposed at an acute angle to-the horizontal in said armed condition.  
  8. The printing machine as defined in claim 1 wherein said beam and the damping tongues carried thereby are disposed a predetermined distance from said printing characters in the armed condition of said striking hammers with said damping tongues each being in overlying deflected engagement with an associated striking hammer, and upon release of selected ones of said striking hammers by said selectively holding and releasing means the associated damping tongues resume their normal undeflected condition in line to intercept the selected ones of said striking hammers during the rebound movement thereof.  
 - 9. The printing machine as defined in claim 1 wherein said means for moving said carriage toward said printing characters include rotatable cam means.  
  10. The printing machine as defined in claim 2 wherein said tongues are constructed from high damping power material.  
  11. The printing machine as defined in claim 4 wherein said machine includes a frame said beam mounting means include a pair of levers, means connecting a first end of each lever to said beam, means pivotally connecting a second end of each lever to said frame, and said connection means connects said carriage to said pair of levers between the first and second ends thereof.  
  12. The printing machine as defined in claim 4 including means for resiliently biasing said carriage for movement in a direction away from said striking hammers whereby return movement of said carriage away from said printing characters after a printing operation is achieved under the influence of said biasing means.  
  13. The printing machine as defined in claim 11 including means for resiliently biasing said carriage for movement in a direction away from said striking hammers whereby return movement of said carriage away from said printing characters after a printing operation is achieved under the influence of said biasing means.  
  14. The printing machine as defined in claim 11 wherein said beam and the damping tongues carried thereby are disposed a predetermined distance from said printing characters in the armed condition of said said printing characters include rotatable cam means.