US2926768A - Single element printing mechanism - Google Patents

Description

March 1, 1960 2 Sheets-Sheet 1 Filed Sept. 25. 1958 S Rmun mmmD JM ru E W V n 1 NW 4 H1 HM. J 1 s V f #W W on E cm 3 mm mm x cm 2 a a Mm om m. s @E m ATTORNEY March 1, 1960 F. E. BECKER EIAL 2,925,768

SINGLE ELEMENT PRINTING MECHANISM 2 Sheets-Sheet 2 Filed Sept. 23, 1958 United States Patent 2,926,768 SINGLE ELEMENT PRINTING MECHANISM Application September 23, 1958, Serial No. 762,753 Claims. (Cl. 19-7--52) This invention relates to printing mechanisms, and more particularly to a' single element print head having improved means for centering it while moving to printing position.

There is shown in an application by I. E. Hickerson et al., Serial No. 547,481, filed November 17, 1955, now U.S. Patent No. 2,895,584, a single element print head which may be rotated and tilted to locate characters selectively in position for printing. Associated with this print head'are balls which are continuously urged by springs into engagement with notched members for detenting the head in its different rotated and tilted positions. Movement of the balls over the notched members produces an objectionable noise and results in a drag on the head, making it necessary that greater energy be used in positioning the head than would be required if the detenting means did not come into operation until the printing positionwwas reached. The action of the balls on the notched members also fails to produce a positive detenting of the head An object of this invention is to provide an improved detenting means for a print head which may be rotated and tilted to present any one of a plurality of characters thereon in printing position.

Another object is to provide for a print head which maybe rotated and tilted as it is moved toward engagement with a platen a detenting means which is operable to positively center the head just before engagement withthe platen takes place.

Still'another object is to provide detent elements which are controlled by a single operating member to effect the centering of a print head in different tilted and rotated positions.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a front vertical section of a single element print head with its operating mechanism, and having associated therewith an improveddetenting device.

Fig. 2 is a vertical section taken on the plane of the line 22 in Fig. 1, but showing the head in a tilted position.

Fig. 3 is an exploded view of the mechanism shown in Figs. 1 and 2 Referring to the drawings, it will be noted that there is shown a print head and operating means therefor generally like that shown and described in the application to Hickerson et a1. referred to above. This comprises a head 1 in the form of a hollow truncated sphere and having characters 2 arranged on its outer surface in rows and columns. Extending downwardly from the upper end of the head is a cylindrical portion 3 resting upon a flange'4 ofa sleeve-shaped member 5 which is rotatably supported by a block 6. Overlying the flange 4 is a plate 7 which is fastened to the block 6 by screws 8 for holdnected at its inner end to a ing the sleeve member 5 on theblock. A cap 10 is of the headlfor holdingithe latter in place.

Brazed to theright hand side of -the block 6, as shown in Figs. 1 and 3, is. a plate 11 having a beveled gear portion12formed thereon. Another plate 14is brazed to projectin 'portions on 'thenleft side of the block and has radially extending teeth 15 along its lower edge. Guided in'openings between the plate 14 and the block is a member 16 which is pivoted at 17 and has a projecting portion18 engageablewith teeth 19 around the lower edge of the print headl for detenting the latter in a rotated position. A springi20 urges the member 16 toward a positioninwhich theportion 18 engages the teeth 19.

Extending along opposite sides of the block 6, see Figs. 1 and 3, are arms 22 of a yoke 23. Pins 24 extend through openings in the yoke arms and the block to support the latter for tilting motion about a horizontal axis. At the lower end of the yoke is asleeve portion 25 extending into an opening in a support 26, and a flange 27 on the sleeve portion 25 engages the top of the support and is attached to the latter by screws 28, as shown in Fig. 2. Extending through the sleeve portion 25 and an opening in the yoke 23 is a tubular shaft 30 carrying a bevel gear segment31 which meshes with the bevel gear portion 12 for operating the latter to tilt the print head about the pins 24. Fixed to the lower end ofthe tubular shaft is a pulley sector 32 which is operated by a tape 33 against the action of a spring 34. Extending through the tubular shaft 30 is a rod36 having an enlarged head 37 at its upper end resting upon the end of the tubular shaft 30. Formed in this head is a recess, and a pin 38 extends across the recess and is received within a slot in a member 39 so as to permit a rocking of the latter about a horizontal axis while it is rotated about its own longitudinal axis by the shaft 36. At the upper end of the member 39 is another slot receiving pin 44) which extends across and is fixed at its ends to sleeve-shaped member 5. Rotation of the member 39 causes the member 5 and the print head 1 to rotate therewith while permitting a tilting of the head relative to the member 39. Connected to the lower end of the rod 36 is a pulley 42 which may be rotated by a tape 43 against the action of a helical spring 44. This spring is con hub portion of the pulley 42, and is connected at its outer end to a housing consisting of a cap 45 and a cover plate 46 attached to the bottom of the support 26 by screws and43 may be actuated by a mechanism like that shown in an application by L. E. Palmer, Serial No. 653,806, filed April 19, 1957, for tilting and rotating the print head 1 to its difierent printing positions.

The support 26 is mounted for rocking motion on trunnions Sll extending into openings in a carrier 51 slidably mounted on a shaft 52. The structure of the carrier 51 and its mounting may be like that described in the Palmer application referred to. The trunnions 50 are made in the shape of sleeves so the tapes 33 and 43 may extend through them to their actuating mechanisms.

Formed in one side of the yoke 23 is a slot 54 guiding a lever 55 which is'pivotally supported by a pin 56 carried by the yoke. The lever has an arm 57 extending through an arcuate opening 58 in the member 16, and another arm 59 projecting below the yoke. Arm 57 acts on the member 16 to position the latter about its pivot 17 and also, when raised, extends between. the teeth 15 on the plate 14 to center the print head in its tilted position. A spring 60 tends to swing the lever 55 to a position for engaging its arm 57 with the teeth 15. With Patented-Mar. l, 1960:

47. The tapes 33 3 wardly by the spring 20 to engage the projecting portion 18 with the teeth 19 on the print head.

Pivotally mounted on the support 26 is a lever 62 engageable with the arm 59 on the lever 55 for rocking the latter in a clockwise direction against the action of the spring 6%. The outer end of the lever 62 is bent downwardly to provide a portion 63 which is engaged by a lever 64 pivotally supported at its lower end on a stud 65 fixed to the carrier 51. Engagement between the lever 64 and the portion 63 of the lever 62 is such that the support 26 may be rocked on its trunnions 50 relative tothe carrier 51 without affecting the actuation of the lever 62 by the lever 64. Mounted upon the shaft 52 between the sides of the carrier 51 is a sleeve 67 which is keyed for rotation with the shaft but is permitted to slide longitudinally thereof. The ends of the sleeve engage the sides of the carrier so that it moves with the latter along the shaft. Fixed to the sleeve 67 by any suitable means is a face cam 68 which acts on a projecting portion 70 of the lever 64 for swinging the latter about the stud 65.

During a printing operation, the shaft 52 is caused to make one revolution. At the beginning of the revolution, the projecting portion 70 on the lever 64 rests against the high portion of the cam 68 so that the lever 64 is rocked to its left hand position in Fig. 3. This causes the lever 62 to be rocked against the arm 59 of the lever 55 to hold the latter in such a position that its arm 57 is disengaged from the teeth 15. At the same time, the arm 57 acts against the member 16 at the lower edge of the opening 58 and causes the member 16 to be rocked downwardly about its pivot 17 so the projecting portion 18 is removed from the teeth 19 around the lower edge of the print head. With the parts in this position, the tapes 33 and 43 may be actuated to tilt and rotate the print head. At the moment in the cycle when the rotating tilting of the head has been completed, the low dwell on the cam 68 comes opposite the projecting portion 70 on the lever 64 and permits the latter to rock in a clockwise direction in Fig. 3. This releases the lever 62 so that it may turn under the action of the lever 55 which is rocked in a counter-clockwise direction by the spring 69. The rocking of the lever 55 results in a swinging of the member 16 to engage its portion 18 with the teeth 19 on the print head and, at the same time, to effect an engagement of the arm 57 on the lever 55 with the teeth 15 on the plate 14. By this operation, a positive centering and locking of the print head in printing position is obtained.

While the print head is being tilted and rotated by the tapes 33 and 43, the support 26 is rocked about the trunnions 50 to bring the print head into engagement with a platen, not shown, for effecting printing. To accomplish this, a cam follower 72 .is provided with an arm 73 extending into a slot 74 in the support 26 and pivotally connected to the latter by a pin 75, as shown in Fig. 1. Formed in the cam follower is a slot 77 receiving the end of a pin 78 which extends through a slot 79 in the side of the frame 51 and is clamped to the latter by a nut 80. Extending from the follower 72 are arms 82 and 35 engaging c-ams 84 and 85, respectively, fixed to the sleeve 67. As the shaft 52 rotates, the cams 84 and 85 act on the arms 82, S3 to rock the follower 72 about the pin 78 and cause the support 26 to swing upwardly about the trunnions 50. The rocking of the follower may be varied by shifting the position of the pin 78 in the slots 77 and 79. The cams are so formed that the driving of the follower 72 is discontinued before the print head strikes the platen. Inertia of the moving parts will cause the print head to continue its movement toward the platen. Connected to the bottom of the support 26 is a member 87 having an arm 88 which engages a cam-shaped anvil 89 mounted on the sleeve 67, and having a hub portion 90 connected to the sleeve by a set screw 91. Engagement with the anvil takes place while the print head is in free flight and just before it contacts the platen. This produces a whipping action in the mechanism supporting the print head to effect a sharp engagement of the latter with the platen. The anvil may be adjusted manually on the sleeve 67 to vary the point at which the whipping action takes place. As soon as a printing operation has been completed, the cam 68 rocks the lever 64 to effect a removal of the detenting members from the teeth 15 and 19 so the print head is free for positioning again by the tapes 33 and 43.

While there have been shown and described the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. A printing mechanism comprising, in combination, a carrier, a rotatable shaft slidably supporting said carrier, a base member pivotally mounted on said carrier, a type head, means mounting said type head on said base member for angular movement relative thereto, means movable with said type head and having detenting teeth formed thereon, an element engageable with said detenting teeth for centering and holding said type head in a printing position on said base member, means operating on rotation of said shaft for rocking said base member on said carrier to effect a printing by said type head, and means including a cam rotatable with said shaft for engaging said element with said detenting teeth just before printing takes place.

2. The mechanism of claim 1 including a sleeve keyed for rotation with said shaft and operatively connected to said carrier for movement therewith, and means connecting said cam to said sleeve.

3. A single element printing mechanism comprising, in combination, a base member, means supporting said base member for pivotal movement about a horizontal axis, a tilt member mounted on said base member for tilting motion relative thereto about a horizontal axis, a type head mounted on said tilt member for rotation about an axis perpendicular to the axis of said tilt member, detenting teeth formed around the lower edge of said type head, an element pivotally connected to said tilt member and engageable with said detenting teeth for centering and holding said type head in a position to which is is rotated, means fixed to said tilt member and providing detenting teeth arranged arcuately about the axis of said tilt member, a member pivotally supported by said base member and engageable with the detenting teeth on said means for centering and holding said tilt member in a position to which it is tilted, said pivot member engaging said element for controlling its position relative to the detenting teeth on said type head, means for rocking said base member on its pivotal support to effect printing by said print head, and means operating just before printing takes place to move said pivotally supported member into engagement with the detenting teeth on said means and to effect engagement of said element with the detenting teeth on said head.

4. A printing mechanism comprising, in combination, a carrier, a rotatable shaft slidably supporting said carrier, a base member pivotally mounted on said carrier, a tilt member mounted on said base member for tilting motion relative thereto about a horizontal axis, a type head mounted on said tilt member for rotation about an axis perpendicular to the axis of said tilt member, detenting teeth formed around one end of said type head, an element pivotally connected to said tilt member and engageable with said detenting teeth for centering and holding said type head in a position to which it is rotated, means yieldingly urging said element toward engagement with said teeth, means fixed to said tilt membeer and providing detenting teeth arranged arcuately about the axis of the said tilt member, a member pivotally supported by said base member for engagement with said arcuately arranged teeth and for controlling the position of said eiement, means including a lever mounted on said carrier and acting against said pivotally supported member, and cam means on said shaft acting against said lever, said cam means normally operating through said lever to hold said pivotally supported member in a position out of engagement With said arcuately arranged teeth, said pivotally supported member operating in such position to hold said element out of engagement with the detenting teeth on said head, said cam means operating on rotation of said shaft to a predetermined point for releasing said lever.

5. A printing mechanism comprising, in combination, a carrier, a rotatable shaft slidably supporting said carrier, 21 base member mounted on said carrier for pivotal moveof said characters for printing, means driven by said shaft for rocking said base member to eifect printing by said head, detenting teeth on said head and said tilt member, and means controlled by said shaft and operable to engage said detenting teeth on movement of said head to a point just short of printing.

References Cited-in the file of this patent UNITED STATES PATENTS 641,916 Wright Jan. 23, 1900 1,141,831

Russell June 1, 1915

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