CA1052432A - Actuator mechanisms for wire matrix printers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A wire matrix printer includes a print head having banks of print wires arranged for linear reciprocation toward and away from a recording surface by associated actuators. Outer or actuator ends of the wires define a vertically spaced and stepped array with actuators also in an array vertically spaced and stepped and respectively coupled to the outer print wire ends by armatures.
The inner or printing ends of the wires define a vertically spaced, nearly planar array near the recording surface, and a spaced, planar array at such surface. The banks are angularly spaced from a line extending perpendicularly from the recording surface, and the inner ends of the wires in each bank are alternately interleaved near the recording surface. The actuators in each bank also include torsion springs, pole pieces, a permanent magnet and an electrical coil about but not mechanically loading each armature. The pole pieces are magnetized by the permanent magnet to normally attract and hold each armature adja-cent thereto against the action of its associated torsion spring, thereby storing potential energy therein. The flux of the permanent magnet is momentarily neutralized for a selected arma-ture by energization of its associated coil to allow the armature too rotate on and about one of its pole pieces for impacting the inner end of the print wire couplet thereto against the recording surface due to conversion of the potential energy stored in the torsion spring to kinetic energy of the armature.

Description

Bellino 4-5-3-10 ~ 3~ Division ~

1 - This application is a division of application serial

2 number 227,828, filed May 27, 1975.

3 INTRODUCTION AND BACI~&ROUND -.

4 This invention relates generally to actuator mechanisms ;~
and more particularly to a compact, rapidly operating and 6 economical arrangement of print wires and actuating mechanisms 7 therefor in a wire matrix printer. The invention also relates 8 to certain features of actuator mechanisms and has particular 9 utility in the selective movement of workpieces such as the print wires, found in wire matrix printers.
11 Matrix printers of various designs have been known 12 for many years. Typical printers generally related to this 13 invention are disclosed in P. A. Brumbaugh et al. U. S. Patent 14 3,672,482; A. S. Chou et al. U. S. Patent 3,592,311; E. B. Finnegan U. S. Patent 3,627,096; R. S. Bradshaw U. S. Patent 3,217,640;
16 W. Wockenfuss et al. U. S. Patent 2,683,410; and K. A. Knutsen 17 U. S. Patent 2,869,455.
18 In various ones of the prior art matrix printers, 19 a column of vertically spaced print wires is usually mounted on a carriage and traversed across the surface of a recording 21 medium or sur~ace, such as paper. In a typical printer using 22 a 5 x 7 dot matrix ~or printed characters, the vertical column 23 of seven print wires travels across the recording medium sur-24 face, five-posi~ions- (or printing steps)-to-the-complete-character. At each possible printing position, selected ones 26 of the print wires (from zero to all seven) are actuated or -27 "fired" to impact or drive based on which wires were actuated.
28 Also, the selected wires may otherwise mark the recording medium 29 in any known fashion such as by punching holes therethrough.

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Bellino 4-5-3-10 Division A
g3 1 This invention, then seeks to improve such matri~
2 printers (1) by providing a rapidly operating, very light, com-3 pact, inexpensive, aasy to make print head and print wire assembly, 4 particularly one with essentially straight print wires, and (2) by providing very small, efficient, compact, easy-to-assemble and 6 extremely rapid actuating mechanisms for operating such print 7 wires. The invention also concerns a new and improved actuator, 8 having general utility in selectively moving workpieces, but 9 especially useful in selectively reciprocating an array of closely spaced parallel workpieces, such as the print wires of a matrix 11 printer.
12 This invention is also concerned with an improved 13 actuator mechanism of the general class disclosed in W. J. Zenner 14 Canadian patent 657,621 and G. Dirks U. S. patent 2,976,801.
The Zenner patent relates to a punch system, including 16 a combination of spring reeds and electromagnets for operating the 17 reeds, to selectively cock and fire the reeds and associat~d punch 18 elements. The present invention relates to improved actuators of 19 the Zenner type wherein potential energy is stored in a spring-like member, which improved actuators are small, compact, and low in 21 electrical power consumption.
22 The present invention, moreover, is also concerned with 23 improved magnetic actuator structures of the general class dis-24 closed in the Dirks patent. The Dirks patent relatPs to a dot printing system which includes a plurality of print levers having 26 printing surfaces thereon. The levers are continuously recip 27 rocated at a point intermediate the ends of the levers. Both ends 28 of each print lever are attracted and held ~y permanent magnets.
29 One of the permanent magnets also includes an electrical coil which, when energized, neutralizes the magnetic flux thereof. The 31 relative strengths of the permanent magnets are such tha~ if a Bellino 4-5-3-10 Division A
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1 particular neutralizing coil is not energi~ed, reciprocation of its 2 associated lever effects movement of the print end of that lever 3 away from its magnet to cause printing. If the coil is energized, 4 reciprocation of the lever moves only the non-printing end of that print lever away from the magnet and printing does not occur. The 6 present invention involves an improvement and simpli~ication of 7 Dirk type actuators by eliminating the continuous reciprocation and 8 one permanent magnet and simplifying other structural elements.
g Actuators of the Zenner type as well as other actuators, such as those of the Brumbaugh et al. and Chou et al. patents rely 11 on converting the potential energy stored in a reed or leaf spring 12 to kinetic energy of a print wire to effect printing. Accordingly, 13 anotper object of this invention is to improve on that concept by 14 using a torsion spring rather than a reed. Simply stated, a tor-sion spring, presents two advantages over a leaf spring. First, 16 in a torsion spring, the storage of potential energy is accom-17 panied by a uniform deformation. This means that other factors 18 (material, size~ being roughly equal, the torsion spring is cap-19 able of storing more potential energy per maximum stress more 20 efficiently and in a more compact manner with potentially less -21 movement than a leaf spring. Second, in a torsion spring, a mass 22 to be driven thereby is essentially divorced from the spring.
23 This i8 not true with a leaf spring wherein a significant part o~ -24 the mass driven is the spring itself. The larger mass of a leaf spring renders it slower in driving an o~ject, such as a print 26 wire. Thus this invention uses these advantages of torsion 27 springs to achieve a compact, efficient, high speed print head.
28 This invention further relates to the construction and geometry of 29 actuator mechanisms which include pole pieces and armatures and to circuit operating principles for such actuator mechanisms and also 31 relates to such actuator mechanisms which use a compact and low r~
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~ 3~ 1 l mass assembly of permanent magnets, pole pieces, armatures, and 2 coils.

4 In accordance with the present invention as applied to a two-position actuator o the type in which an armature is 6 attracted to a first position by a magnet against the action of a - 7 resilient member, thereby storing potential energy in the member, 8 which energy biases the armature toward a second position, and 9 selective energization of an elec~ric coil neutralizes the magnetic attraction of the magne~ for the armature to permit the resilient ll member to move the armature to the second position, an improvement 12 wherein the resilient member is a torsion spring; and the coil 13 surrounds, but does not mechanically load the armature.

FIG. l is a perspective view of a portion of a wire 16 matrix teleprinter, in accordance with the present invention, 17 viewed from a paper or other recording medium and looking toward 18 an operator's position and at the front of a print head according l9 to this inv~ntion;
FIG. 2 is an enlarged ragmentary perspective view of a 21 portion of the print head used in the teleprinter of FIG. l 22 according to the present invention, viewed from the operator's 23 side (the upper right in FIG. l);
24 FIG. 3 is a vertical section along line 3-3 of FIG. 2 illustrating the rear of one of a plurality of actuators of the 26 print head of this invention and a portion of a guide structure for 27 plural print wires operated by the actuators;
28 FIGS. 4 and 5 are a top and a side view, respectively, 29 of FIG. 3 taken along lines 4-4 and 5-5 of FIG. 3 and showing two adjacent actuators of the print head;

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1 FIG. 6 is a vertical eIevation along line 6-6 of FIG. 2 2 showing the geometry and relationship of a bank of the actuators 3 of FIGS. 3-5, their associated print wires, and the guide structure 4 therefor according to this invention;
FIG. 7 is a schematic, fragmentary perspective view 6 (not to scale) of the print wires depicted in FIGS. 3-6 and a 7 portion of the actuators therefor, illustrating some of the 8 basic principles of wire ma~rix printing, including typical 9 matrix characters printed according to the present inven~ion;
FIGS. 8 and 9 depict in greater detail the geometry 11 of printing ends of the print wires shown in FIG. 7 and their 12 relationship to other parts of the teleprinter of FIG. 1, wherein 13 FIG. 8 is a top view of the print wires in an unfired and a fired 14 state, and FIG. 9 is a side view of the wires in an unfired state;
FIG. 10 is a schema~ic, fragmentary (not to scale) 16 top view of several armatures of the actuators of FIG. 2 similar -17 to FIG. 4, showing both rest positions and fired positions of :~
18 the armatures and their associated print wires; :
19 FIG. 11 is a perspective view of the guide structure 20 for the print wires of the print head shown in part in FIGS. 3-6 -21 viewed from the same general perspective as in FIG. 1 in which -~
22 the guide block is not shown;
23 FIG. 12 is a sectional view taken along the line 12-12 24 of FIG. 11 showing additionally portions of the ac~uators of the present invention similar to FIG. 3;
26 FIG. 13 is a front view taken along line 13-13 of 27 FIG. 11;
28 FIG. 14 is an electrical schematic illustrating a 29 circuit for opera~ing the actuators of this invention; and FIG. 15 is a partial, detailed, side elevation of 31 pole pieces for the actuators of the present invention.

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Bellino ~-5-3-10 Division A

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2GENERAL PRINTER STRUCTUR~
3 FIGS. 1-5 4Referring first to FIGS. 1, 2, and 6, a wire matrix printer is illustrated which includes a print head 10 in accord-6 ance with one preferred embodiment of this invention.
7 The head 10 is mounted on a conventional carriage 11 for 8 linear traversing movement in a horizontal direction (designated X) 9 across a record medium, such as a paper 12 on which printing or other marking or punching is to take place. As viewed in FIGS. 1, 11 7, 11, and 13, ~he print head lO travels from right to left during 12 printing, similar to certain conventional typewriters and then 13 returns from the left to the right after each line has been printed 14 on the paper 12. In FIGS. 2, 3, 4, 10, and 12 which are all viewed from the operator's perspective, the print head 10 moves from left 16 to right during printing. When the terms "left" and "right" are 17 used hereafter they refer to the perspective of FIGS. 2 et al.
18 The~print head 10 includes a plurality of print 19 wires 21-27, seven being illustrated in FIGS. 1-5, 7-9, 6, and 11 for a conventional 5 x 7 dot matrix. Printing, free or inner 21 ends 30 of the print wires 21-27 are equally spaced vertically, as 22 shown at 31, in FIGS. 7 and 9 to print successive vertical 23 columns a-e o~ dots 32 (FIG. 7) on the paper 12 as necessary to 24 form selected characters 33 or other information or data thereon.
As is well known in the matrix printer art, the print wires 21-27 26 are selectively actuated as the head 10 traverses the paper 12 to 27 ~orm the charactexs 33 via a matrix (columns a-e) of the dots 32.
28 When the head 10 contains a single column of the seven print 29 wires 21-27, the traversal of the carriage 11 and the head 10 pro-vides the X dimension of a conventional 5 x 7 dot matrix, as is -31 well known, and the vertical print wire spacing 31 provides the Z
32 (height or vertical) dimension (FIGS. 7 and 9) o~ the characters 33.

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1 If lower case letters are to be printed, or if other more complex 2 characters or patterns are to be formed, then 7 x 9 or even larger 3 matrices are used, for example, by adding two or more print wires 4 to the wires 21-27 oX the print head 10.
Returning to FIGS. 1, 2, 4, and 6; the carriage 11 6 continuously traverses the paper 12 in the X or printing direction 7 by a reversible, constant speed, drive motor 34, which may turn a 8 belt and pulley transmission 35 to rotate a conventional helical 9 lead screw 36 on which the carriage 11 is threadedly mounted by a carriage nut 37 (FIG~ 6). Preferably, the carriage nut 37 is the 11 type described in commonly assigned Canadian patent application of 12 Arthur F. Lindberg, Serial No. 215,902, filed on December 12, 1974.
13 Alternatively, the carriage 11 may be driven in step-by-step 14 fashion across the paper 12 with the print head 10 stopping at each possible printing column a-e during its traversal across the 16 paper 12. The carriage 11 is mounted ~or linear reciproca~ion in 17 the X direction on a pair of guide rods 40 (FIGS~ 1 and 4), and is 18 reciprocated by the drive motor 34 between the left-hand start-of-19 line (extreme right of FIG~ 1) and the right-hand end-of-line (extreme left of FIG~ 1) positions in a generally conventional 21 fashion.
22 As the print head 10 travels across the paper 12 in the 23 X or printing direction past each possible printing position, such 24 as a-e in FIGo 7J selected ones of the print wires 21-27 are "fired"
or actuated "on-the-fly" to print a column a-e of from zero to seven 2~ vertical dots 30. As best depicted in FIGS. 4 and 5, the "firing"
27 or actuating of a wire 21-27, that is, a wire selected to effect 28 printing, is accomplished as follows: The selected wire 21-27 is 29 driven a short distance D (FIGS. 8 and 9) in the horizontal direction Y (perpendicular to both X and Z and to the paper 12) 31 thus impacting the printing end 30 of the selected wire or , - : '' ' ~ . ' , :

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5~3~ 1 1 wires 21-27 against a type ribbon 41 and further driving the 2 ribbon 41 and superjacent portions o the paper 12 against a backing 3 member or platen 42 in a well known manner.
4 When a desired length of a line 43 of characters 33 has been printed, or when ~he end-o-line position is reached, the

6 carriage 11 is returned to the start-of-line position and the

7 paper 1.2 is stepped upwardly one or more character lines 43 (see

8 FIG. 7) in the Z direction, as in a eonventional typewriter. Pre~-

9 erably, this is done automatically by a line feed mechanism 44 in preparation for the printing o~ following lines 43. While any known 11 line feed mechanism 44 may be used in accordance with the present 12 invention, one preferred mechanism 44 may be used in accordance with 13 the present invention, one preferred mechanism 44 is that se~ forth 14 in commonly-assigned copending Canadian application of Ingard B. Hodne, Serial No. 215,816, filed December 12, 1974. Gen-16 erally, the line feed mechanism 44 includes a coupling or clutch 45 17 responsive to a line feed signal which positions a platen gear 46 18 enmeshed with a speed reduction gear 47 for a preset time interval 19 during carriage return from the end-of-line position to the start-of-line position to rotate the platen 42 and to step the paper 12.
21 The gear 47 in turn is driven by a drive gear 50 mounted on the 22 lead screw 36 as shown in FI~. 1.
23 Various other arrangements for effecting relative 24 movement of the print head 10 and the paper 12 may be utilized.
For example, in printing the lines 43, the platen 42 may be rotated 26 and the paper 12 stepped a desired number of lines 43 at the end-27 of-line position of the head 10 and the next line 43 may be printed 28 on the return stroke while the carriage 11 is moving back to the 29 start-of-line position. Moreover, to print graphs or other pat- ;
terns generally referred to as "plotting," the platen 42 may be ::

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Bellino ~-5-3-10 Division A
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1 "rolled" (selectively moved up and down) independently of movement 2 of the carriage 11 by appropriate incoming data signals via cir-3 cuitry (not shown) connected to the drive motor 3~ to provide a 4 variable dimension to the graph or pattern. Moreover, the carriage 11 may be independently movable by a "slide-on-slide"
6 arrangement such as by using a linear electric motor of the type 7 s'nown in A. G. Wallskog Canadian patent 936,808, or G. Cless 8 Canadian patent 956,588. Other details o~ the carriage 11 and 9 other portions of general printing mechanisms and operating cir-cuits are not critical to thP present invention and may be arranged 11 as described in Brumbaugh et al. patent as well as the other matrix 12 printer patents previously cited.

Referring now to FIGS. 1-9 and 11 and especiall~ FIGS. 2 16 and 5-9 there is shown a preferred layout of the print wires 21 27 17 in accordance with certain principles of this invention.
18 In a preferred embodiment, the print head 10, is divided 19 into two halves or banks 10A and 10B, left and right banks, respec-tively, as viewed in FIG. 2. The print wires 21-27 are preferably 21 divided as equally as possible between the two banks 10A and 10B.
22 Center lines 51A and 51B of the banks 10A and 10B (FIGS. 2, 8, and 23 10) are angularly separated by an angle ~, which in the described 24 example is about 5, although other angular spacing may be used.
The center lines 51A, 51B, are in turn angularly separated by an 26 angle ~ from the center line 51 of the head 10 leaving a wedge~
27 shaped space between the banks 10A and 10B. ~ is about 2-1/2 in 28 this e~ample. The center line 51 lies on a common plane wi~h the 29 Y direction and is mutually perpendicular to both the X and Z
direction as well as to an impact line 53. The impact line 53 31 (FI&. 7) is the curved line which could be drawn between ~he .

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1 printing ends 30 of the wires 21-27, should all be "fired", where 2 such printing ends 30 impact on the ribbon 41 (lower part of 3 FIG. 8) in printing the columns a-e.
4 The print wires 21, 23, 25, 27 are contained in and actuated by the left bank lOA and the print wires 22, 2~, 26 are 6 contained in and operated by the right bank lOB, although the 7 reverse arrangement may also be used. The free ends 30 of the 8 wires 21-27 are alternately interleaved as shown in FIGS. l, 2, 5, g and 11 immediately adjacent to the impact line 53.
Of course, a single bank or more than two banks may be

11 used, if desired. In the former, no interleaving would be neces-

12 sary; in the latter cyclic alternate interleaving would preferably

13 be used.

14 The printing ends 30 of the print wires 21-27 are immediately adjacent and slightly separated from the impact 16 line 53 when all of the wires 21-27 are unfired.~ Such ends 30 are 17 arranged in a~spaced, vertical arrangement which is an almost per-18 fectly vertical, slightly staggered column, as shown in FIGS. 7, 8 l9 (top) and 13. At the impact line 53, assuming all of the wires 21-27 are fired, a perfectly vertical column of their print-21 ing ends 30 is formed (FIG. 1 and the lower part of FIG. 8). The 22 staggering in the unfired state is due, of course, to the angular 23 relation of the banks lOA and lOB, and to the fact that when the 24 wires 21-27 are unfired, a small distance D (FIGS. 6 and top of FIG. 8) exists between the printing ends 30 and the ribbon 41, 26 The distance D may vary from .010 to .060 inch and is typically 27 .035 inch within this range.
28 Specifieally, the printing end 30 of the topmost wire 21 29 as seen in FIGS. 2 and 8 (top) (FIGS. 8 and 1~, and as viewed from the paper 12) and the end 30 of every other odd-numbered wire 23, .

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1 25, and 27 is slightly to the left of the center line 51, while the 2 ends 30 of the even-numbered print wires 22, 24, and 26 are 3 slightly to the right thereof. The sa~e staggering is shown in ~ :
4 FIGS. 7, 11 and 13, but as viewed from the paper 12 so that, of course, "left" and "right" are reversed. As viewed from the top 6 in FI~. 8, the print wires 21-27 converge through the included 7 angle 9 (approximately 5 degrees, although this angle may be 8 adjustable) toward the impact line 53.
9 As shown in FIG. 7, the printing ends 30 of the wires 21-27 immediately adjacent the impact line 53 may be 11 machined to conform precisely to the curvature of the platen 42 as 12 shown from the side in FIG. 9. Moreover, as viewed in FIG. 8, the 13 wire ends 30 may be machined so that such ends are parallel to the 14 platen 42.
In any event, when one or more respective print 16 wires 21-27 are actuated or "fired", the wire moves forward toward 17 the platen 42 impacting the printing end 30 flatly against the 18 ribbon 41, and sandwiching the paper 12 between the ribbon and 19 the platen 42 along the impact line 53, the ends 30 of any actu-ated print wires 21-27 precisely conforming to the surEace of the 21 paper 12 held on the platen 42.
22 In a preferred embodiment, the wires 21-27 are 23 fabricated of music wire, or the like, approximately .013 inch in 24 diameter. The print wires 21-27 are, accordingly, relatively stiff and can be readily reciprocated short distances in the Y
26 direction to print characters without significant distortion or 27 bending.
28 Distortion or bending of the wires 21-27, as well as any 29 attendant lack of registration between the printing ends 30 and the impact l~ne 53, may also be obviated by a guide block 54 -~ 31 associated with the left and right-hand banks lOA and lOB of the ,. ..
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Bellino 4-5-3-10 Division A
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1 print head 10 as shown in FIGS. 2-6 and 11 and as discussed in 2 detail below. For simplicity, the guide block 5~ is not shown in 3 FIG. 1. Further, the guide block although preferably present is 4 not absolutely necessary, depending on the stiffness and other characteristics of the material constituting the wires 21-27. For 6 example a simple guide (not shown) a~ or near the printing ends 30 7 may suffice to vertically support and guide the wires 21-27.
8 The diameter and the vertical spacing 31 (for example, 9 .016 inch center to center) of the wires 21-27 are both dictated by the dot 32 size and the vertical spacing 31 desired in the 11 printed characters 33. In the specific operating embodiment of 12 the present invention, adjacent print wires 21-27 are vertically 13 spaced 31 by approximately .016 inch center-to-center a~ the 14 printing ends 30, and by twice that amount (.032 inch) in the banks lOA and lOB.
16 The wires 21-27 are of generally uniformly increasing -17 lengths proceeding upward from the bottom wire 27 to the top : .
18 wire 21 in the bank lOA and from the bottom wire 26 to the top 19 wires in the bank lOR as shown in FIGS. 1, 2, 6 and 11. This arrangement, as well as the vertical spacing 31 of the 21 wires 21-27, effects a horizontally-spaced, vertically stepped and 22 spaced configuration of actuator, fired or outer ends 55 of the -23 wires 21-27. In this example, the wire lengths vary uniformly 24. from about .750 inch for the bottom wires 27 and 26 in the respec 25 tive banks lOA and lOB to 2.250 inches for the top wires 21 and -26 22, again in the respective banks lOA and lOB. This straight, 27 parallel, horizontal wire configuration with the horizontal spac-28 ing and vertical spacing and stepping at the outer ends 55 29 achieves a compact, light, and economical print head assembly of closely spaced print wires, according to the invention. Because 31 the wires 21-27 are required to reciprocate only the very short ~ -13-.

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Bellino 4-5-3-10 Division A
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1 distance D in the Y direction, the wire lengths are made as short 2 as practically obtainable.

4 For simplicity, the guide block 54 is not shown in FIG. 1. However, referring to FIGS. 2, 3, 6, and 11, the 6 wires 21-27 may be periodically supported along their lengths and 7 at both their inner or printing ends 30 and their outer or 8 ac~uator ends 55 for precise horizontal reciprocation by the guide 9 block 54 which is associated with both banks 10A and 10B. The block 54 is made of DELRIN or other rigid, low friction material 11 and may be mounted to a mounting frame 56 or to the banks 10A, 10B
12 (the latter being preferred), in any convenient manner. Other 13 elements of the head 10 are also mounted to the frame 56 which has 14 a central cutou~ 57 for servicing the head 10 from below,and through which pass certain electrical connections as explained 16 more fully below. The frame 56 in turn, is mounted to the 17 carriage 11. Typically, this latter mounting may be effected by 18 a plurality of screws 60 as shown in FIGS. 1, 2, and 6.
19 The guide block 54 includes a pair of similar, horizontal, elongated members 61A and 61B. The members 61A and 21 61B are fastened together at their forward ends (in the Y sense) 22 and separated at their rearward ends to form a wedge 61 having a 23 wedge-shaped opening therein. The fastening of ~he members may be 24 by any convenien~ means, e.g. a screw, or the wedge 61 may be made, as by molding, in one piece. The wedge 61 oceupies the space 26 between, and extends at least the leng~h of, the banks 10A and 10B.
27 The wedge 61 subtends an angle equal to 0 or about 5. Formed 28 integrally with the members 61A and 61B are a plurality of 29 upstanding inger-line guides 63 aligned in pairs in the X direc-tion one guide 63 in each pair being respectively on the 31 members 61A and 61B. The guides 63 on each member 61A and 61B are - Bellino 4-5-3-10 Division A
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1 aligned along a line parallel to the respective axes 51A and 51B.
2 The guides 63 contain a plurality of parallel, horizontal vertic-3 ally spaced grooves 64 formed therein either during molding 4 thereof or by a material removal operation The grooves 64 may assume any desired cross-sectional configuration (a rectangular 6 one being shown) which constrains wires 21-27 therein both vertic-7 ally and laterally. As viewed from the rear (FIGS. 3 and 12) ~ corresponding grooves 64 in the guides 63 on one or ~he other side 9 of the wedge 61 are aligned. That is, the topmost groove 64 in all the guides 63 on the one member 61A are aligned horizontally. In 11 the example shown, as viewed in FIGS. 3 and 12, the guides on the 12 right member 61B of the wedge 61 have three grooves 64, and 13 guides 63 on the left member 61A have four, corresponding, of 14 course, to the number of print wires 21-27 in the respective banks lOA, 10~
16 The outer ends 55 of the wires 21-27 are vertically 17 stepped, as shown in ~IGS. 5, 6 and 10, and such ends 55 are hori-18 zontally spaced from each other in the Y direction. The guides 63 19 are formed to occupy these spaces. In the example shown, the guides 63 are about .500 inch apart.
21 The grooves 64 are at a height such that when the guide 22 block 54 is mounted either to the plate 56 or directly to the 23 banks lOA and lOB, the wires 21-27 are received therein, the topmost 24 grooves 64 in the guides 63 of the left member 61A receiving the uppermost wire 21 of the left bank lOA, the topmost groove 64 in 26 the guides 63 of the right member 61B receiving the uppermost 27 wire 22 of the right bank lOB, etc. The wires 21-27 are constrained 28 in their respective grooves 64 by a wedge-shaped closure 66.
29 The closure 66 may be elongated bar,having a plurality of wedge-shaped, upstanding fingers 67 thereon, the entire ~1 closure 66 belng entirely complementary in shape to the inside

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1 facing surfaces of the members 61A and 61B. Fingers 67 are so 2 located that when the closure 66 is located between the right and 3 left-hand guides 63 within the space 65 the fingers 67 mate with 4 the guides 63 to close the grooves 64. The closure 66 may be attached to the wedge 61 by any convenient means such as screws or 6 an adhesive.
7 With the closure 66 attached to the wedge 61 the 8 wires 21-27 are periodically supported along their lengths at each 9 guide 63. This support not only accurately positions the wires 21-27, but also obviates any sideways deflection or being of ~-11 the wires 21-27 as their printing ends 30 impact on the ribbon 41.
12 It should be pointed out that the guide block 54 merely 13 constrains the wires 21-27 to maintain the free, natural orienta-14 tion and configuration they would normally assume without the block 54 except for external influences, such as deformation during

16 a printing stroke and gravity. This is particularly true at the

17 printing or free ends 30.

18 As pointed out in describing FIG. 1 (in which the guide

19 block 54 is not shown) the free wire ends 30 assume an interle~ved, nearly vertically aligned, slightly staggered configuration 21 FIGS. 7, 11 and 13). This configuration is maintained by an 22 upstanding forward nib 68 attached to the front of the member 23 wedge 61. The nib 68 is in two halves 68A and 68B formed respec-24 tively at the front of the members 61~ and 61-B. The nib 68 contains (in this example) seven bores 70 having exactly this stag-26 gered configuration at the very front of the ifinger 68 (FIG. 13) 27 four of the bores 70 being respectively alignéd with the grooves 64 28 in the guides 63 on the left member 61A and three of which are 29 similarly aligned with the grooves 64 in the guides 63 on the right member 61B.

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~ Bellino 4-5-3-10 Division A
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1 The wires 21-27 and the guide block S4 are preferably 2 preassembled as in FIG. 11, this assembly then being associated 3 with the rest of the print head 10 as described below.

5 The outer or actuator ends 55 of the wires 21-27 are ~;
6 formed into loops 71 as shown in FIGS. l-ll, and especially in 7 FIGS. 5 and 7. The loops 71 serve as tension mounts, described 8 below, and also serve a guiding function for the wires 21-27 in aid 9 of the guides 63 and the finger 67. ;~
The loops 71 are generally U-shaped, the rear arm 72 of 11 the U running first toward the front arm 73 of the U and then from 12 a bend 7~ away from such front arm. A leg 75 of the U inter-13 connects the arms 72 and 73, the length of the leg 75 being -14 greater than the distance between the arms 72 and 73 at the bend 74.
16 The leg 75 and the lower, wider part of the front and ;~
17 rear arms 72 and 73 adjacent thereto are contained in and con-18 strained by a channel 76 partly formed in the inside and top 19 surfaces of each wedge 61A and 61B. The channels 76 are completed by the side surfaces of the closure 66 and reside between the 21 guides 63 in the Y direction. Such constrainment of the loops 71 -22 prevents both lateral displacement of ~he outer or driven ends 55 23 and rotation of the wires 21-27 on their major axes. The distance `
24 between the guides 63 and the fingers 67 is sufficient to permit enough movement of the loops 71 so that the wires 21-27 may travel 26 the distance D.
27 ACTUATORS - GENERAL; FIGS. 1-6, 10-15 28 As mentioned above, the print head 10 is divided into two 29 banks 10A and 10B. Each bank has a number of actuators 80 for the wires 21~27. The left-hand bank 10A includes a plurality of ~1 actuators 80-1, 80-3, 80-5, and 80-7, which selectively fire the .
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~ 43'~
1 print wires 21, 23, 25 and 27, respectively, associated therewith.
2 The right-hand bank 10B includes a plurality of actuators 80-2, 3 80-4 and 80-6, which selectiveIy fire the print wires 22, 24 and 4 26, respectively associated therewith. In the description of the preferred embodiment, the left-hand bank 10A includes four 6 actuators 80; the right-hand bank 10B three. This could, of 7 course, be reversed. Moreo~er, if instead of the 5 x 7 matrix 8 (having the seven print wires 21-27) of the preferred embodiment, 9 a matrix of 7 x 9 (having nine print wires~ is used, the added wires are divided as nearly as possible between the two banks 10A
11 and 10B for firing thereby. Thus, there is no more than a one-wire 12 difference between the total number of wires fired by the two 13 banks. Other than the number of print wires 21-27 associated 14 therewith, each bank 10A and 10B is essentially the same, the two being mirror images of each other, and, other than their height and 16 location, each actuator 80 in a given bank is the same as the 17 others. Each wire 21-27 is associated with its respective 18 actuator 80, in a manner described more fully below and the 19 actuators 80 in each bank 10A and 10B are vertically stepped and ~ ;
horizontally spaced in a manner similar to the actuator or driven 21 end 55 of the print wires 21-27.
22 Spe~ifically, each actuator 80 includes an armature 81 23 pivotable or rotatable on an axis 82 thereof, the construction of 24 the armatures 81 and the manner of their pivoting being described subsequently. A finger or extension 83 on, and pivotable with, 26 each armature 81 extends into the space 52 between the banks 10A
27 and 10B, and is coupled to the loop 71 at the actuator or outer 28 end 55 of one print wire 21-27 (see below), so that pivoting move- -29 ment of an armature 81 toward the platen 42 "fires" its coupled wire 21-27 and prin~ing is effected. Movement and or maintenance Bellino 4-5-3-10 ~ivision A
~.CIS~

1 of the armatures 81 away from the platen 42 effects non-printing 2 of the print wires 21-27. Movement of the print wires 21-27 toward ~ -~
3 and away from the platen 42 is guided by and constrained by the 4 guide block 54, as described above.
Except for their vertical height relative to the mounting 6 plate 56 and their varying distances from the platen 42, the 7 actuators 80 are the same.

9 Referring especially to FIGS. 1-6 and 12 each bank 10A, 10B contains a pair of pole pieces or plates 84 and B5. The pole 11 pieces 84 and 85 are parallel to each other in each bank and con-12 tain a plurality of generally aligned slots or cut-outs 91-94.
13 Conveniently, the pole pieces 84 and 85 may be fabricated by a 14 simple stamping operation from the appropriate ferromagnetic metal.
Similar plates 84-84 and 85-85 are, as assembled in the head 10, 16 mirror images of each other.

.
18 The right-hand plate 84 in the left bank 10A and the 19 left-hand or inside plate 84 in the bank 10B contain a series of :
essentially vertical slots or cut-outs 91 having a step at the 21 front thereof and being flat at the rear. The slots 91 define a 22 plurality of vertical projections 95 therebetween the top rear of 23 each of which is chamfered as shown at 96, and the rear of which 24 is stepped while the front surface 97 of which is flat. (See FIGS. 2 and 5.) 26 The effective width of the slots 91 in the Y direction 27 and at the upper end of the projections 95 is more than sufficient 28 to allow for pivoting movement of the armatures 81 therein.
29 Specifically, as described later, armature movement comprises rota-tion of the armature finger 83 about the armature axis 82 due to 31 pivoting of the armature 81 on such axis 82. Moreover, the .

.

Bellino 4-5-3-10 Division A
~ 3~
1 e~fective Y direction distance between the front surface 97 of any 2 one projection 95 and a baCk surface of the guide 63 adjacent the 3 next orward slot 9, must also be sufficient to permit such rota-4 tion. The vertical depth of the slot 91 is determined by magnetic flux concentration and isolation consideration, discussed subse-6 quently. Suffice it to say that flux considerations aside, the 7 slots 91 must have sufficient depth to accommodate the vertical 8 dimension of the armatures 81. The front surfaces 97, of the 9 projection 95 as well as the slots 91 are horizontally spaced in the Y direction in a manner similar to the spacing of the loops 71 11 at the actuator ends 55 of the wires 21-27. Bottom surfaces 100 12 of the slots 91 are vertically stepped upwardly from front-to-back 13 similar to the vertical stepping of the wire ends 55.
14 At the bottom of the plate 84 are slots or cut-outs 93, having somewhat the general shape of a backward F as viewed from 16 the space 52 between the banks 10A and 10B (FIGS. 5 and 6). The 17 slots 93 are generally vertically aligned with the projections 95.
18 The horizontal parts of the F 93 are genPrally semicircular in 19 shape and define a tab 101 therebetween having a forward facing (i.e. acing the platen 42), flat, vertical surace 102.
21 Between the bottom of the slots 91 and the top of the 22 slots 93 are flux isolation slots 92. These latter slots 92 23 create, within the limits of mechanical strength, the narrowest 24 tolerable land portions 104 and 105, respec~ively, in the plates 84, as shown, for a purpose discussed later. The slots 92 26 are generally vertically aligned with the rear hal of the slots 91.

28 The outside plates 85 are similar in most respects to the 29 plates 84 and similar reference numerals have been used for cor-responding features. Features with the same reference numerals and

-20-,. .. .

Bellino 4-5-3 10 Division A

1 in a given bank 10A and 10B are aligned from plate to plate as 2 viewed perpendicular to the plates' major surfaces (i.e., in the 3 X direction). The projections 95 on the plate 84 are not cham-4 fered as they are on the plate 84. Moreover, unlike the slots 93 in the plate 84, "F"-shaped slots 94 in the plates 85 are forward-6 facing as viewed rom the outside of the head 10. The horizontal 7 parts of the F 94 are also generally semicircular in shape and 8 define a tab 105 therebetween having a generally backward facing, 9 (i.e., away from the platen 42), 1at vertical surace 106. Pairs of the F slots 93 and 94 in a given "bank" are generally aligned 11 X-wise, 12 As viewed generally in the X direction, the flat ront 13 surfaces 97 of corresponding, aligned projections 95 are aligned.
14 That is, a line drawn therebetween is perpendicular to the major surfaces of the plates 84 and 85, and to the center lines 51A or 16 51B of the respective banks 10A or 10B. Referring to FIG. 10, how- -17 ever, and as viewed in the same manner (X-~ise) a line drawn 18 between the corresponding surfaces 102 and 106 of the generally .. .....
19 aligned tabs 101 and 105 defines an angle with the superjacen-t line drawn between the surfaces 97, because of an offset between the

21 surfaces 102 and 106. The offset is such that the surace 102 of

22 the tab 101 on the plate 84 is forward of (closer to the platen 42

23 than) the surface 106 of the tab 105 on the plate 85 as viewed on

24 a line perpendicular to the center lines 51~ and 51B.
Beside serving as magnetic pole pieces, the plates 84 and 26 85 are the mechanical frame for the banks 10A and 10B.

28 Each armature 81 includes a rectangular member 110 29 designed to be positioned in pairs of aligned slots 91-91 in the plates 84 and 85 in the banks 10A and 10B. The fingers 83 are con--31 nected to, and are preferably integral with, the members 110 and - . . , . -. , . . . ~ ~ . : .

Bellino 4-5-3-10 Division A
~ ~ 5 ~ ~ 3 1 protrude beyond the projections 95 into the space between the -~
2 banks lOA and lOB. In the unfired or unactuated position, the 3 members 110 are maintained with their aligned slot pairs 91-91, a 4 portion of the members 110 immediately adjacent the fingers 83 resting 1ush against the front surface 97 of the projection 95 in 6 the plate 84. In the same position a portion of the members 110 `~
7 remote from the fingers 83 rests flush against the front surface 97 .
8 of the projection 95 in the plate 85. Pivoting of the armatures 81 :~
9 about their axes 82 is effected by using an outside corner 116 of the surfaces 97 of the projections 95 on the outside plates 85 as 11 a pivot point for the members 110. Such pivoting results in the 12 rotation of the member 110, and the finger 83 toward and away from 13 the platen 42 to effect selective printing or non-printing of the 14 print wires 21-27 connected to the fingers 83 by the loops 71. Use of the corner 116 as a simple pivot is one of the major simplifying 16 features of the present invention. ~peration of armatures 81 as 17 described for 109 cycles resulted in no detectabl~ deleterious wear 18 at the interface of the corner 116 and the member 110.
19 Attached to and preferably, formed integrally with each member 110 is a vertically disposed elongated torsion spring 118 21 in the preferred form of a rod-like member having a rectangular 22 cross-section and formed by the same stamping operation which forms 23 the member 110 and its integral finger 83. The torsion springs 118 24 are maintained on the outside (left of the plate 85 in the bank lOA;
right of the plate 85 in the bank lOB) of the outside plates 85, the 26 major axis 120 thereof being generally parallel to, but slightly 27 displaced from, the pivoting axes 82, of the armatures 81, which 28 axes coincide with the corner 116. While the thickness of the tor-29 sion springs 118 may be the same as that of the members 110, their width must in any event be such as to permit torsional deformation 31 thereof for storage therein o~ potential energy. Typically, the .
Bellino 4-5-3-10 Division A

. 1 torsion springs 118 measure .028 inch generally in the ~ direction 2 (thickness) and .055 inch generally in the X direction (width).
3 Attached to, and preferably formed integrally with and 4 at the same time as, ~he torsion springs 118 are horizontal mount-ing bars 122. The bars 122 are used to mount the armatures 81 to 6 the pole pieces 84 and 85 for rotation as follows: The rectangular 7 members 110 are inserted into respective slots 91 in the plate 85 8 simultaneously with ~he insertion of the bars 122 into the slots 94 9 also in the plate 85. Continued insertion results in protrusion of the finger 83 from the slot 91 in the plate 84 and into the 11 space 52, as described above, the protrusion of an end of the 12 bars 122 from the slot 93 in the plate 84 also into the space 52. . -.
13 Opposite ends of the bars 122 immediately adjacent the ~orsion . :
1~ springs 118 are located outside the plates 85.
The ends protruding from the slot 93 may be bifurcated 16 as shown at 126 and 128. The furcations 126 and 128 reside on 17 either side of a lower, horizontal, rearward facing tab 130 formed 18 in the plate 84 beneath and slightly longer than the tabs 101, the 19 web between the furcations 126 and 128 resting on the top of the tab 130. Tabs 131, similar to the tabs 130 but forward facing are 21 formed in the plate 85 beneath and slightly longer than the 22 tabs 105. Both ends of the bar 122 rest on the top of these latter 23 tabs 131. The bar ends, the tabs 130 and 131, and the ' 24 furcations 126 and 128 all cooperate to maintain the bar 122 against thQ surfaces 102 and 106 of the tabs 101 and 105 in the 26 plates 8~ and 85, respectively.
27 Due to the offset of the surfaces 102 and 106 of the 28 tabs 101 and 105, such mounting of the armatures 81 results in the 29 members 110 assuming a neutral position whereat each member 110 rests against and is pivo~ed on the corner 116 of the ~1 projection 95 on the plate 85 at the same angle as the bars 122 ...

~: , . .. .

Bellino ~-5-3-10 Division A
~Q~ 3~ .
1 relative to a perpendicular to the major surfaces of the plates 84 2 and 85 (as well as to the center lines 51A and 51B) and the 3 finger 83 is spaced forwardly of the front surface 97 of the 4 projection 95 in the plate 84.
After assembly in the banks 10A and 10B, the tops of the . 6 bars 122 are stepped upwardly from front to back, again, similar 7 to the stepping of the ends 55 of the wires 21-27.
8 ACTUATORS - MOUNTING OF WIRE;S 21-27 THERETO
.
9 The wires 21-27 are mounted to their respec~îve armatures 81 by inserting the fingers 83 into the respective 11 loops 71. Specifically, the distance between the bend 74 and the :
12 ~ront arm 73 of the loop 71 is slightly less than the thickness of 13 the fingers 83 so that the fingers 83 are engaged therebetween.
14 Preferably, after the armatures 81 are all assembled in their respective banks 10A and 10B, such armatures are quickly, expediti-16 ously and simultaneously associated with their print wires 21-27 17 which have already been mounted in and constrained by the guide 18 block 54.
19 Because the armatures 81 rotate on their axes 82, and because the guide block 54 laterally constrains both the 21 wires 21-27 and their respective loops 71, the loops 71 must be 22 free to slide over the surface of the fingers 83. Specifically, 23 from the standpoint of the laterally constrained loops 71, rota-24 tion of the armatures 81 resul~s in an effective shortening thereof, thus slightly sliding the fingers 83 with respect to the 26 loops 71. The loop-finger 83-120 fit, is designed to permit such 27 sliding to take place. Again 109 operations of such an arrange-28 ment resulted in no wear serious enough to adversely affect the 29 operation of the print head 10.

Bellino 4-5-3-10 Division A
:~O~i~43~
ACTUATORS - PERMANENT MAGNETS
2 An elongated, upwardly sloping (from back to front) 3 cavity 132 is deined by the inside, facing vertical walls of the 4 plates 84 and 85, an imaginary plane defined by the stepped tops of the bars 122, and an imaginary plane defined by the stepped tops 6 of the slots 92. Into this cavity 132 in each bank 10A and 10B and 7 in direct contact with the plates 84 and 85 is inserted an elon- --8 gated permanent magnet 134 preferably a ceramic magnet, which when g magnetized has a magnetic permeability about the same as that of 10 air. As viewed in ~IG. 2, when the magnet 134 in the left bank 10A ;`- -11 is veiwed from the rear, the North pole is to the left while the 12 South pole is to the right. The reverse may also be true. The 13 magnet 134 in the right bank 10B may have its South pole to the 14 left and the North pole to the right, thus minimizing magnetic linkage between the two banks 10A and 10B. On the other hand, 16 from the viewpoint of assembly the print head 10, it is usually 17 preferable to have the North poles of both magnets 134 face the 18 same way (left or right) as well as the South poles (right or 19 left). While this latter arrangement may increase the flux linkage between ths banks 10A and 10B to some extent (between the facing, 21 oppositely magnetized poles of the magnets 134 along the center 22 line 51), it offers facility in assembling the head 10. Specific-23 ally, the magnets 134 may be inserted into their respective 24 cavities 132 in an unmagnetized state after assembly of the pole pieces 84 and 85 with the armatures 81. Prior to mounting the 26 wires 21-27 to the armatures 81, armature-pole piece assembly may 27 be conveniently subjected to a strong polarizing field as from a 28 horseshoe ele~tromagnet (not shown3 associated with ~he assembled 29 head 10 80 as to magnetize the ceramic magnets 134 in a well-known manner.

-25-r~
^-' Bel'lino 4-5~3-10 Division A

~ 3~
1 Preferably, the ultimate strength of the magnets 134 is 2 such that four ends are realized:
3 (A) First, the members 110 of the armatures 81 are 4 normally pulled against the respective'front surfaces 97 of the projections 95 in the plate 84 to rotate'the armatures 81 into the 6 unired position. Because such rotation of the members 110 varies 7 from the previously defined neutral position to torsionally distort 8 the torsion springs 118, potential energy is stored therein.
~ Each flux path or magnetic circuit is: From the North pole of the magnet 134, through land area 136 defined by adjacent 11 flux isolating slots 92, through the front surface 97 of the 12 projection 95 on the plate 85 through the member 110, through the 13 front surface 97 of the projections 95 on the plate 84, through 14 land area 136 on the plate 84, to the South pole of the magnet 134.
It should be noted that the chamfer 96 serves its function in the 16 magnetic circuit. Specifically, it has been found that reducing 17 the width of the projection 95 near the finger 83, as by the 18 chamfer 96, concentrates the flux to more effectively rotate and lg hold the ar~ature 81 in the rest position.
(B) The end 124 of each bar 122 is held against the 21 surface 102; the end 125 is held against the surface 106. In both 22 cases the force due to the magnetic attraction of the tabs 101 and 23 105 for the ends 124 and 125 is in aid of the mounting function 24 performed by the tab-end 131-125 and the tab~end-furcations 130-124-126/128. The magnetic forces are sufficient to maintain the

26 described position o the bars 122 notwithstanding any pivoting

27 motion of the members 110. This is in part due to the flu~ con-

28 centrating effect of the tabs 101 and 105 of the F's 93 and 94 in

29 attracting and holding the bar 122. It should be noted that the magnetic attraction between the tabs 101 and 105 and the bar is 31 also quite strong because of the pro~imity of the magnet 134 ' ' ' ' ,:

Bellino 4 5-3-10 I Division A

1 thereto. Of course, the bar 122 may be mechanically mounted to the 2 plate 84 or 85 or to the mounting frame 56 by deformation, screws, 3 rivets or an adhesive, but the mounting described is preferred due -4 to its simplicity and the ease of assembly the armatures 81 and plates 84 and 85, as well as to the convenient formation of the 6 cavity 132.
7 Each flux path is: From the North pole of the 8 magnet 134, through the land areas 136, through the tabs 101 and 9 131 through the bars 122, through the tabs 105 and 130 in the plate 84, through the land areas 136 in the plate 84 to the South 11 pole of the magnet 134.
12 (C) The members 110 are held against either the front 13 surface 97 of the projection 95 in the plate 84 (when the 14 armatures 81 are unfired) or against the outside corner 116 of such surface 97 (when the members 110 are pivoted away from the front 16 surface 97 of the projection 95 in the plate 84). In this way the 17 pivoting of the members 110 on the corners 116 is quite simple - no `
18 bearings, hinges or ~he like are necessary - the magnetic attrac-19 tion of the corner 116 therefor being suffi~ient.
(D) The plates 84 and 85 are maintained in a rigid, 21 stable structure. ! `
22 ACT~ATORS - ELECTROMAGNETS
23 As described above, the basic actuator ~0 for the print 24 wires 21-27 includes the stamped metal armatures 81 (comprising the finger 83, the member 110, the torsion spring 118, the bar 122), 26 the stamped metal pole pieces 84 and 85 (including the 27 slots 91 94), and the permanent magnets 134, all assembled together 28 with the wires 21-27 in the guide block 54 in a simple structure to 29 form the banks 10A and 10B.

. . . .

Bellino 4-5-3-10 Division A
~ 5~ ~ 3~ -~
1 Each actuator 80 also includes facilities 138, such as 2 an electric coil, for effecting the selective firing of its associ-3 ated print wire 21-27.
4 The function of each coil 138 is, upon selective application thereto of a voltage, to counteract or neutralize the 6 magnetic flux normally holding the portion of the member 110 adja-7 cent the finger 83 against the front surace 97 of the 8 projection 95 in the pla~e 84. Such counteraction on neutraliza-g tion permits the stored potential energ~ in the torsion spring 118 to rapidly move the member and finger (110 and 83~ forward toward 11 the platen 42, thus "firing" the associated print wire 21-27 to 12 effect printing on the paper 12.
13 Each coil 138 includes a bobbin 140 made of a phenolic 14 resin or other convenient electrical insulator. Wound on the bobbin 140 are a plurality of turns 142 o~ an insulated wire of a 16 sufficient number and in a proper direction and having sufficient 17 current carrying capacity to counteract the magnetic flux of the 18 permanent magnet 134 at whatever point in the actuators 80 the 19 coils 138 are located as discussed below.
The~preferred mounting position for the coils 138 has 21 been found to be a position surrounding, but not mechanically load-22 ing, the members 110. Specifically, flanged ends 144 of the 23 bobbins 140 are mounted between the plates 84 and 85 to the 24 interior faci!ng surfaces of the projections 95 in such a way that a central bore 146 of the bobbin 140 surrounds its associated 26 member 110. Because the volume swept out by the member 110 during 27 rotation of the armature 81 in a wedge having a rectangular cross-28 section, the bore 146 is preferably rectangular in cross-section, 29 although oth~r configurations may be used. Of course 9 the bore 146 is sufficientl~J large so as not to interfere with the pivoting of 31 the member 110 about the corner 116. Such mounting of the flanged .

. .

~ Bellino 4-5-3-lO
Division A
~ ~ 5 ~

1 ends 144 may be effected by locating fingers 148 formed integrally 2 with the bobbin flanges 144 and which are complementary in shape 3 to the stepped shape of the slots 91 in the plates 84 and 85. Of 4 course, other mounting schemes may also be used, as, for example, adhering a part of the flanges 144 to the projections 95 with an 6 appropriate adhesi~e. This latter scheme somewhat facilitates the 7 winding of the wire turns 142 on the bobbin 140 by eliminating the 8 locating fingers 148.
9 Application of an appropriate voltage to the coil 138 results in the generation of magnetic flux, the coil 138 and the 11 member 110 together acting as an electromagnet 138/110. This flux 12 counteracts the flux of the permanent magnet 134 such that a ;
13 selected print wire 21-27 is "fired". The counteracting flux as 14 viewed in FIG. 2 is primarily con~ined to a magnetic circuit as -follows: From the electromagnet's north pole (here the portion of 16 the member 110 remote from the finger 83) through the air to the 17 south pole (here the portion of the member 110 adjacent the 18 finger 83). Any tendency of the flu~ of one coil 138 to affect an 19 armature 81 other than its own armature 81 (so-called "crosstalk") is obviated by two features, namely, the slots 91-94 and the near-21 air permeability of the ceramic magnet 134. A third feature, the 22 thickness of the member 110, may also be adjusted to obviate 23 crosstalk.
24 First, the slots 91-94, as discussed previously, have the effect of creating narrowed land portions, such as those at 103, 26 104 and 136. Viewed from the standpoint of the flux generated by 27 the coil 138 in the electromagnet 138/110, the magnetic path from 28 north to south through the plates 84 and 85 (i.e., the path from 29 the north pole of the electromagnet 138/110, through the adjacent projection 95; through the lands 103 and 104 on the plate 85; up 31 through the next forward, and/or rearward projection 95 on ': . .

Bellino ~-5-3-10 Division A
~5'~ 3~
1 plate ~5 through the next forward or rearward member 110; down 2 through the adjacent projection 95 on the plate 84; through 3 lands 103 and 104 on the plate 84, up through the projection 95 on 4 plate 84 adjacent the south pole of the electromagnet 138/110) has a much higher magnetic reluctance than the magnetic circuit (the 6 member 110 and air) associated with the particular 7 electromagnet 138/110 energized.
8 Second, the permeability of the permanent ceramic 9 magnets 134 being about equal to that of air, as is well-known, there is no lower reluctance path than the one just described 11 between the plates 84 and 85 above the lands 102 and 103. In fact, 12 any path through the permanent magnet 134 probably has an even 13 higher reluctance than the more tortuous path through such 14 lands 102 and 103.
Third, although not necessary, the thickness of the 16 members 110 may be increased, as by attaching thereto a piece of 17 a ferromagnetic material to further decrease the reluctance 18 thereof. The reluctance of the magnetic path formed by the 19 member 110 and air for the electromagnet 138/110 may thus be so lowered as to essentially prevent any crosstalk.
21 It should also be noted that movement of onè of the 22 members 110 away from the front surface 97 of the projection 95 23 potentially has the effect of increasing the magnetic attraction 24 between other members 110 and their respective projections 95.
Specifically, the flux from the permanent magnet 134 formerly pass-26 ing through the now-pivoted member 110 tends to divide itself via 27 the pole pieces 84 and 85 through any non-pivoted members 110, 28 because the now-formed air gap between the pivoted member 110 and 29 the projection 95 increases the reluctance of that member's mag-netic circuit as to permanent magnet flux. However, the 31 combination of the slots 91-94 and the smallness of such air gap,

-30-~. . :
,, ', .

Bellino 4-5-3-10 Di~ision A
Z
- . .
1 being typically .045 inch, nearly obviates this effect. In any 2 event, each coil 138 may easily be so designed as to be able to :
3 generate sufficient magnetic flux to permit pivoting of its 4 associated armature 81 over the entire range of possible attractive forces between its related member 110 and the projection 95.
6 Referring now to FIGS. 3 and 12, the two ends 149 of the 7 wire 142 wound on each bobbin 140 are respectively positioned 8 adjacent to a pair of horizontal apertures 150 formed through the ~
9 lower part of the bobbin flange 144 which abuts the inside surface ~ . :
10 of the inside plates 84. The apertures 150 are aligned with "L"- `
11 shaped bores 152 formed in the locators 148. The bores 152 run 12 first horizontally away from the apertures 150 and then downwardly 13 to the end of the locator 148 near the bottom 100 of the slot 91.
14 The bores 152 contain a pair of rigid wire members 154 which run vertically down past the end of the locator along the outside of 16 the plates ~4. The upper ends of the wire members 154 are con-17 nected, as by soldering, to the ends 149 of the wire 142 near the 18 apertures 150. The lower ends of the wire members 154 are con-l.9 nected by appropriate means to a drive circuit 156 for each coi]. 138. Typically, the coils 138 are assembled with the plates 21 plates 84 and 85 by sliding the locators 148 into the complementary 22 shaped slots 91 prior to assembly of the armature 81 thereon. Such 23 assembly of the armatures 81, then, entails in part insertion of 24 the member 110 into the bore 146. As shown in FIG. 12, assembly of the guide blocks 54 may effect rigid placement of the coils 138 26 in the preferred embodiment where an adhesive is used to attach the 27 flanges 144 to the plates 84 and 85. Specifically, when the 28 block 54 is attached to the plates 84 and 85 as by screws 157 :~.
29 (FIG. 2) the members 61A and 61B of the wedge 61 bear against and lock the locators 148 as well as locating the guide block 54.

-31-. . . :, ' , ~
. '. . .................................................... :
. ' . ' ' ' ' ' ' ' ' ' : .

-~ ~ellino 4-5-3-10 Division A

~V~ 3~
1 Typically, the connection between the wire me~bers 154 2 and the drive circuit 156 may comprise in part printed circuit 3 paths 158 formed on a printed circuit board 158 (FIGS. l, 2 and 6) 4 in any well ~nown ~anner. In the preferred embodiment described, the printed circuit board 158 is located above the cutout 57 of the 6 frame 56 and may be attached at its front and rear ~o the hold 7 down 86 and the frame 56, respectively, by screws 161 as shown in 8 FIGS. 2 and 6. Conveniently, the paths 158 are connected to the 9 drive circuits 156 by a flexible cable and plug 162 (FIG. 6) which runs from beneath the board 160 to such circuits 156 located else-ll where in the teleprinter. The wire members 154 pass through 12 apertures 163, which may be plated through-holes, in the board 160 :13 and are connected to their respective printed circuit paths 158 by 14 soldering.

16 The function of the drive circuits 156 is to selectively 17 apply a voltage to one or more selected coils 138 to generate a 18 current in the wire 142 thereof which in turn generates a magnetic 19 field for counteracti~g or neutralizing the magnetic field of the permanent magnet 134. Ideally, due to power and speed considera-21 tions, the current ~hrough the coil 138 should rise sufficiently 22 fast and be of su~ficient magnitude to generate the counteracting 23 magnetic field as quickly as possible; then such current and the 24 counteracting magnetic field should both decay in a manner so that printing is effected. After printing, the current and the result-26 ing counteracting field should be low enough so that the 27 armature 81 is returned primarily due to the magnetic pull of the 28 permanent magnet 134 to its rest position in the shortest possible 29 time.

-32-' '.', ' .'" ;: ,, .: ~' :
' ',~ ' ' ' ,~ , , ;

~ellino 4-5 3-10 Division A
4L3'~

1 Specifically, experimentation has shown that it is during 2 the decay of the current in the coil 138 that the armature 81 moves 3 to print. More specifically, due to mechanical inertia of the 4 armature-inger-spring 81-83-118 and to the finite time it takes for the field of the permanent magnet 134 to become sufEiciently 6 neutralized in a particular armature 81 to permit movement thereof, 7 the torsion spring 118 begins to move such armature at a time near 8 that at which the coil current reaches its maximum. As coil cur-9 rent decays, the influence of the permanent magnet 134 on the ~-armature 81 begins to increase even though the armature 81 and the 11 finger 83 may have moved away from the projection 95. Thus, if 12 decay of the coil current is too rapid, the armature 81 either does 13 not move at all, or is pulled back to the rest position before 14 printing is ever effected. If such decay is too slow the arma-ture's print wire 21-27 may remain "fired" for too long (tearing 16 the paper 12 on the ribbon 41) and the repetition rate o~ the 17 head 10 becomes too slow. Thus, the control circuit 156 should be 18 capable of striking a balance between quite rapid and quite slow 19 decay o the coil current.
Also, the rise of the coil current, while not playing a 21 direct role in armature movement is, of course, necessary so that 22 sufficient flux is generated to counteract the field of the 23 permanent magnet. If this rise is too slow, not only is the head's 24 repetition rate slowed, but also power consumption increases. A
"too rapid" current rise is not detrimental, and~ if practical, may 26 increase the head's repetition rate. -27 It should also be noted that coil curren~ decay is 28 usually completed before the armature 81 returns to the rest 29 position. Thus, in general, each cycle of operation of a given armature starts with ~eginning of current rise in the coil and ends 31 with the return of the armature to the rest position.

-33-.
.

Bellino 4-5-3-10 Division A

~ 3~
1 ~eferring now to FIG. 14 an example of a simple 2 electrical drive circuit 156 for accomplishing the above ends are 3 depicted. Other arrangements may similarly be used as long as the 4 criteria described above are met.
Referring to FIG. 14, each drive circuit 156 includes the 6 coil 138 o~ one of the actuators 80. The coil 138 is connected in 7 parallel with a diode 164. The cathode of the diode 164 and one 8 end of the coil 138 are connected to a voltage source 166 such as 9 plus 40 volts D.C. The anode of the diode 164 and the other end of the coil 138 are connected to the collector 168 of a normally 11 off transistor 170. The emitter 172 of the transistor 170 is 12 grounded.
13 When it is desired to effect the printing of a selected 14 print wire 21-27 appropriate logic circuitry 174 connected to the base 176 of the transistor 170 generates a pulse which turns the 16 normally off transistor 170 on. Turning on the transistor 170 17 opens a conductive path from the voltage source 166 through the 18 coil 138 to ground through the emitter 172 and the collector 168.
19 As noted previously the direction of thè winding of the wire 142 on the bobbin 140 and the number of turns thereof are such that the 21 current passing through the coil 138 is sufficient to counteract or 22 neutralize the field rom the permanent magnet 134. After the 23 logic circuitry 174 has generated the pulse for firing the selected 24 print wire 21-27, the transistor 170 returns to its normally off condition. At this point in time current tends to continue to flow 26 through the coil 138. Such current now circulates in the circuit 27 through the diode 164 until it is dissipated. That is, such cur-28 rent slowly decays back toward zero. As the current decays toward 29 zero the counteracting or neutralizing effect of the coil 138 is continuously decreased, ultimately permitting the field of the 31 permanent magnet 134 to pull the armature 81 back to its rest

-34-:

/ `
Bellino 4-5-3-10 Division A
~ 3 1 position against the surface 97.
2 ACTUATORS ~- MISCELLANEOUS
3 As shown in FIGS. 4 and 10, the armatures 81 may be 4 partially covered by a layer of polyester film or tape 250 at selected locations. Typically the film is about .002" thick. The 6 film has been found to prevent fretting corrosion especially at the 7 interface of the armature member 110 and the corner 116.
8 A first possible location for the tape 250 is on the g portion 112 of the member 110 adjacent the finger 83. Specific-ally, the film 250 is adhered to the portion 112 in any convenient 11 way so that it is sandwiched between that portion and the front 12 surface 97 of the projection 95 on the plate 84 when the 13 armature 81 is in the rest position. The film 250 thus provides 14 a "built-in" gap between the member 110 and the surface 97 to pre-15 vent the member 117 "freezing" therebetween. As is well known, 16 the magnetic attraction between two ferromagnetic objects dQcrsases 17 as the square of the distance between them. Thus, it is slightly 18 easier for the torsion spring 118 to move the armature 81 upon 19 neutralization of the permanent magnet 134 by the coil 138 when the film 250 is used.
21 Another advantage realized by use of the film 250 at the 22 first location is that upon the rapid return of the armature 81 to 23 the rest position, rebound or bounce of the arma~ure 81 from the 24 surace 97 is reduced. Reduction of this rebound is achieved by the damping effects of the film 250 which depends on judicious 26 selection of the material of the film 250.
27 A second possible location for the film 250 is at the 28 interface of the member 110 and the corner 116. Here, the film 250 29 effects a wear reducing function and may with appropriate selection effect a lubricating function, as should be obvious.

-35-Bellino 4-5-3-lO
Division A
~ 32 1 As in the case of the first position, a "built-in" gap 2 is created by the film 250 at the interface of the second position.
3 Such gap resides between the portion 114 of the member 110 and the 4 front surface 97 of the projection 95, on the plate 85. This gap is not necessarily as desirable as the first gap, but the 6 permanent magnet 134 has suf~icient strength to maintain the 7 portion 114 adjacent the film 250 on the corner 116 during pivoting 8 of the armature 81.
9 A third possible loca~ion ~or the film 250 is on the finger 83. As noted above, because the armatures 81 rotate on 11 their axes 82, and because the guide block 54 prevents any lateral :
12 (X direction~ movement of the wire 21-27, including the loops 71 13 thereof, the effective "shortening" of the armature 81 causes the 14 finger 83 to slide beneath the front loop arm 73 and the bend 74.
5 Thus, the film 250 on the finger 83 both prevents wear and pro- :
16 vides lubrication for such sliding.
17 The film 250 may be placed on the members 110 at one or ~ :
18 more of the three possible locations. Conveniently the film is 19 placed thereon in a single piece overlying both the front and back surfaces of the flngers 83 and then running along and covering the 21 back side of the member 110 where it contacts the respective 22 surfaces 97.
23 Each actuator 80 may include a tension adjustment 256 24 for altering the amount of potential energy stored in the torsion springs 118. Specifically as shown in FIGS. 3 and 10 (left side) 26 a boss 258 having a threaded hole 260 therethrough may be formed 27 on the outside of the plates 84 immediately behind the 28 furcation 126 of the end 124 of the bar 122. Threaded into each 29 hole 260 is a set screw 262 bearing against the furcation 126.
Rotation o the screw 262 to move the furcation 126 and the bar 31 end 124 forward toward the platen 42 increases the amount o .

. . . ~ ' ~.

Bellino 4-5-3-10 Division A
~'3~ 3~3 1 potential energy in the torsion spring 118, considering the 2 armature 110 to be held in the rest position by the magne~ 134, by 3 further increasing the angle B.
4 Other arrangements may be used for adjusting tension.
` 5 For example, individual set screws (not shown) may be mounted to 6 the inside of the plate 84 behind the furcation 178 in a manner : 7 similar to that described immediately above. On the other hand as i 8 shown in FIG. 10 (right side) a single tension adjustment 264 for 9 all of the torsion springs 118 in a single bank 10A or 10B may be - 10 used. Specifically, bosses 258 similar to those discussed above 11 are similarly located on the plate 84. Only the hole 260 on the 12 forwardmost boss 258 is threaded, however, the rest of the 13 holes 260 being unthreaded. An elongated shaft 266 having its 14 front end threaded into the forwardmost boss 258 passes slidably through the other holes 260 via notches 268 formed in the ends 124 16 of the arms 122. Attached to the shaft 266 and bearing respec-17 tively on the arm ends 124 are a plurality of collars 270.
18 Rotation of the shaft 266, then, moves ~he ends 124 backward or 19 forward simultaneously to adjust the tension in the torsion springs 118.
21 Either tension adjustment scheme may be useful when 22 greater force at the printing ends 30 is desired, as, for example, 23 when numerous carbon copies of the data printed on the paper 12 are 24 desired. O course, giving due consideration to the strength of the magnet 134, the flux concentration at the surface 102, and the 26 attraction between that surface and the arm end 124 care must be 27 taken not to move the end 124 so far from the surface 102 that the 28 magnetic attraction therebetween is broken. Generally, tension 29 adjustment will effect only small incremental distances between the end 124 and the surface 102. Gross tension in the spring 118 is, 31 of course, determined by the o~fset between the surfaces 102 and , ;

Bellino 4-5-3-10 Division A
~5~ 3 1 106 as discussed previously.
2 Although several specific embodiments of the invention 3 are shown in the drawings and described in the foregoing specifica-4 tion, it should be understood that the invention is not limited to such specific embodiments, but is capable of modification and 6 rearrangement and substitution of parts and elements without 7 departing from the spirit of this invention. For example, instead 8 of the angularly related banks lOA and lOB, the print head 10 may 9 contain print wires all-in-a-line. Also, it may be desirable to mount the coils 138 elsewhere than surrounding the armatures 81, 11 for example on one or both projections 95 of each actuator 80. ~ -12 Moreover, the relative locations of the members 110, the torsion 13 springs 118 and the connection between the print wire loops 71 and 14 the fingers 83 may be changed and altered as desired. ~-. ..

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Claims (24)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An improved two position actuator of the type in which an armature is attracted to a first position by a magnet against the action of a resilient member, thereby storing potential energy in the member, which energy biases the armature toward a second position, and selective energization of an electric coil neutralizes the magnetic attraction of the magnet for the arma-ture to permit the resilient member to move the armature to the second position, wherein:
(a) the resilient member is a torsion spring; and (b) the coil surrounds, but does not mechanically load, the armature.

2. The actuator of claim 1 wherein the armature is mounted on the torsion spring for rotation about a torsional axis of the spring, and the magnet is a permanent magnet normally attracting the armature to the first position when the coil is de-energized.

3. The actuator of claim 2 which further comprises:
(c) a pair of pole pieces respectively adjacent opposite poles of the magnet, both pole pieces contacting the armature in the first position, the armature being rotatable on a first of the pole pieces to move the armature away from a second of the pole pieces when the armature moves to the second position.

4. The actuator of claim 3 which further comprises:
(d) an elongated member attached to the armature for movement therewith to move one end of the member into a selected position when the armature is in its second position and to move the end away from the selected position when the armature is in its first position.

5. The actuator of claim 4 wherein the armature is elongated, one end thereof being attached to the torsion spring and being adjacent to the first pole piece, the other end thereof being rotatable about the spring's torsional axis into contact with the second pole piece at the first armature position and away from the second pole piece at the second armature position, the actuator further comprising:
(e) an elongated member attached to the armature for movement therewith so that first end thereof is in a selected position at the second armature position and away from the selected position at the first armature position.

6. The actuator of claim 5 wherein the pole pieces comprise a pair of generally mutually parallel fingers, the fingers being parallel to the torsional axis of the spring and perpendicu-lar to the direction of armature movement.

7. The actuator of claim 6 wherein a second end of the elongated member is attached to the armature at the other end thereof.

8. A bank having a plurality of the actuators set forth in claim 7 wherein the first ends of the elongated members are separated from each other at the selected position to define a matrix.

9. The actuator bank of claim 8 wherein the major axes of the elongated members are mutually parallel, and which further comprises:
(f) means for mounting the elongated members for reciprocating motion along their major axes upon movement of the armature.

10. The actuator bank of claim 9 which further comprises:
(g) a first common plate member on which the first fingers are mounted; and (h) a second common plate member on which the second fingers are mounted, the plate members respectively contacting opposite poles of the magnet.

11. The actuator bank of claim 10 wherein the first and second fingers of each pair of fingers are mounted to their respec-tive plate members on the same side of the armature.

12. An actuator head comprising a plurality of the banks of claim 11 wherein the first ends of the elongated members are alternately interleaved at the selected position.

13. A print head for a matrix printer comprising the actuator head of claim 12, the head printing on a record medium, wherein the elongated members are print wires and the record medium is located at the selected position, the print head further comprising:
(i) means for traversing the first print wire ends across the record medium; and (j) means responsive to movement of the first print wire ends to the selected position for printing a dot on the medium.

14. An improved two position actuator as recited in claim 1 wherein:
the armature is mounted on the torsion spring for rotation of a rotational axis of the armature and about a torsional axis of the torsion spring; and the magnet comprises a permanent magnet normally attracting the armature to the first position.

15. The actuator of claim 14 wherein the magnet further comprises a pair of ferromagnetic pole pieces both contacting the armature at its first position, the pole pieces being respectively adjacent the opposite poles of the permanent magnet.

16. The actuator of claim 15 wherein the pole pieces comprise:
(d) respectively, spaced-apart first and second elongated fingers, the first finger having an edge coinciding with the rota-tional axis and remaining in contact with the armature during rotation thereof toward the second position, armature moving away from the second finger during rotation thereof toward the second position.

17. The actuator of claim 16 wherein the spring is elongated and attached at one end to the armature, the actuator further comprising:
(e) a ferromagnetic arm attached to the other end of the spring; and (f) means on the pole pieces for holding the arm stationary during rotation of the armature.

18. The actuator of claim 17 wherein the arm holding means comprises:
(g) tabs on the pole pieces for magnetically attracting and holding the arm by applying the flux of the magnet thereto.

19. The actuator of claim 18 wherein the arm, the fingers and the armature define a cavity for holding the magnet.

20. The actuator of claim 19 which further comprises:
(h) means for moving the arm about the torsional axis of the spring to adjust the amount of potential energy stored in the spring when the armature is in the first position.

21. The actuator of claim 15 which further comprises:
(d) an elongated member having an end;
(e) means for mounting the member for movement of the end into and away from a selected position; and (f) means responsive to movement of the armature to the second position for moving the end into the selected position, and responsive to movement of the armature to the first position for moving the end away from the selected position.

22. The actuator of claim 21 wherein the member mounting means comprises:
a guide block;
a plurality of guide fingers having apertures therethrough for receiving the member periodically along the length of the member;
a U-shaped loop formed in the member; and a channel in the block intermediate the guide fingers which receives the bridge of the U and a part of the legs of the U adja-cent the bridge for sliding motion therein.

23. The actuator of claim 22 wherein the guide finger apertures and the block channel are so arranged that movement of the member is linear and along the major axis thereof.

24. The actuator of claim 23 wherein the end moving means comprises:
an extension of the armature held in the U and engaged by the legs of the U.