CA1045570A - Type carrier print deflection blocking means for a single element printer - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A single-element type carrier printing mechanism is provided with an element movable to block tangential deflection of the type carrier at printing impact with the platen, is normally disengaged from frictional contact with the type carrier during rotational positioning of the type carrier. The deflection blocking element includes a blocking arm pivotally mounted for free rotation relative to the type carrier, provided with an abutment adapted to act against a blocking surface form on the type carrier. The blocking arm is also provided with teeth for detent engagement, with a tilt detent device which moves the blocking arm from its normally disengaged position into engagement with the blocking surface to prevent impact deflection.

Description

~455~
BACKGROUN~ OF THE INVENTIO~
The invention relates to a single-element printer for a typewriter and more particularly to an arrangement for prevent~
ing deElection of the type carrier during printing impact with the typewriter platen.
This invention is an improvement of the single-element ;
type carrier support apparatus described in U.S. Patent 3,924,726 by ~erbert Decker, issued December 9, 1975. The patent describes ;~
a typehead support which includes a support member having a projecting abutment adapted to act against a support surface :; .....
formed on the type carrier to preclude downward tangential movement of the type carrier resulting from a component of the impacting force, thereby to prevent blurring or smearing of the printed type character. While the apparatus achieves its intended purpose, it has been found that friction which develops between the support member and the support surEace of the type carrier has an undesirable effect during the rotational position-ing motion of the type carrier. One suggested solution to this problem is to leave an air gap between these two surfaces. This solution, however, would have a disadvantageous effect on the 'I . .
quality of the typing.
Broadly speaking the present invention provides, in -a single element printer comprislng: a hollow inverted cup-shaped type carrier havlng type characters on its outer periphery located in rows and columns, a platen, a tilt bridge axially supporting the type carrier for rotational movement to :' :
position a selected column of type characters opposite the ~laten, the tilt member having detent teeth thereon, support means pivotally~ supporting the tilt bridge for tilting movement about a tilt a~is to pos~ition a selected row of type characters opposite the platen, the support means being movable from a rest-position to a printing position to impact a selected type character against the platen, the type carrier on impact dap/

~.~9,55~
experiencing deEormation with lower portions tending to move tangentially relative to the platen and support member, the type carrier having a blocking surEace located in a radial plane, a blocking arm freely pivotally supported on the tilt axis having a radially extending abutment located opposite the platen and proximately beneath and spaced from the blocking surface for arresting tangential movement of the typehead relative to the platen and relative to the support member on impact of a selected type character against the platen, means on the tilt bridge and the blocking arm for supporting the blocking arm spaced from the blocking surface, the blocking ar~ having teeth which extend bet~een the detent teeth on the tilt bridge, and tilt detent means movable into engagement with detent teeth on the tilt bridge and teeth of the blocking arm for movlng the block-lng arm and its abutment lnto engagement with the blocking surface and for finally tiltably positioning the tilt bridge.
SUMMARY OF THE INVENTION
Thus, a single-element type carrier printing mechanism i9 provided with means which block de~lection of the type carrier at printing impact with the platen, yet which are disengaged from frictional contact with the type carrier during rotational positioning of the type carrier. The deflection blocking means lncludes the blocking arm plvotally mounted for free rotation relative to the type carrier, the arm having the abutment adapted to act against the blocking surface formed on the type carrier and teeth for detent engagement with detent means whicb selectively engage the blocking arm with the blocking surface to prevent impact deflection or wbich allow disengagement of the arm from the blocking surface to allow frictionless rotational positioning of the type carrier.
A recess may be proviaed in the arm for the receipt of a finger extending from a tilt brldge rotatably supporting the type carrier. The recess and finger are dimensioned and dap/

4S57C) con~igured to provide substantial play therebetween. The tilt bridge is also provided with teeth for detent engagement with the detent means. When the type carrier is in the non-printing position, the blocking arm is pivoted downwardly under its own weight so that the upper surface of the recess in the arm rests against the upper surface of the finger. In this position, the abutment on the blocking arm is disengaged from the blocking surface on the type carrier and the type carrier may thus be rotationally positioned free from frictional contact with the blocking arm. Also in this position, the teeth on the blocking arm are positioned so as to protrude into the gaps deEined by the recesses between the detent teeth on the tilt bridge. When the Cype carrler is p~sitiDned '', ' ': .
. .
I

~ , . .

; ' ' ' ' - 3a - ' `

dap/

557~
for printing and is being driven to print, the detent means acts against the teeth on the blocking arm to drive the blocking arm upwardly and outwardly, pivoting the arm so that the abutment engages the blocking surface on the type carrier, preventing tangential escape of the type carrier on impact, and thus preventing blurring or smearing of the printed character.
j' Additionally, the detent means moves between the tilt bridge teeth and the teeth on the blocking ~nm to fina~ly ~nd pr~ci~ely tilt positl~n the type carrier to print the deslred character.

OBJECTS OF T~-IE INVENTION
¦ An object of the invention is to block the downward tangential ¦ motion oi the type carrier incident to impact to prevent blurrlng or smearing o the printed type character during printing, yet to permit friction-free rotational positioning of the type carrier.
It i9 an additional ob~ect of the invention to s~lpport the type ! carrier during it~ downward tangential motion by means which are simple, accur~te and trouble-free, Other obiects and many of the attendant advantages of the present invention wiLl become apparent to those skilled in the art from a reading of the following detailed description taken in conjunction with the accompanying drawing wherein like reference characters designate like parts and primed reference characters designate equivalent parts and wher~ein:

BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a partial cross-sectional view of the type carrier head and type carrier support means shown in print impacting position.
Figure 2 is a det~il showing the final tilt positioning and print ~eflection blocking detent means in non-impacting position.
Figure 3 is a detail showing the final tilt positioning and print ¦ deflection blocking detent means in print impacting position.

¦ F~gure 4 is a cross-sectional detail of the typle carrier support ¦ means engaging the type carrier head illustrating an embodiment wherein the type carrier print deflection blocking means is provided with rotatlonal detent means.
_ 4 -I
- .... : .,, : .. , ., , .. ~. . . . .

~0~557~
~ igure 5 is a cross-section of an additional embodiment of the type carrier print deflection blocking means having an alternative rotational detent means provided therein.
DETAILED DESCRIPTION OF THE INVE~TION
Referring to Figure l of the drawing, a type carrier, generally indicated by numeral l0, is shown having a generally inverted hollow cylinder or barrel shape and having vertical columns and horizontal rows of raised type characters 12 spaced around the outer periphery of the type carrier wall 14. ~:
Type carrier l0 i5 supported on arbor 16 fixed on shaEt ~ :
18 rotatably mounted on til-t bridge 20 which is pivotally mounted on forked impact arm 22 by means of pivot pin 24 deEining a tilt ~.
axis for tiltably positioning type carrier l0 to present the desired row oE type to the face oE platen 26. ~ tilt position-ing arm 28, pivotally connected with tilt bri.dge 20 by means of pivot pin 30, i8 connected with means not shown to tilt the type carrier to a selected row pOSitiOII, Type carrier l0 is also keyed to arbor 16 for rotational : positioning to present the desiFed column of type opposite ` 20 platen 26.
; On command, type carrier l0 is rotat:ionally positioned by conventional means not shown and finally positioned by a rotate de-tent (not shown) associated with rotational detent teeth 32 formed at the internal surface of type carrier wall 14.
At the same time, the type carrier is tiltably positioned by.
forces transmitted through arm 28 to pivot tilt bridge 20 and .
thereby tilt the type carrier, and is impacted against platen 26 by the movement of arm 22. The roational positioning, tilt -positioning and impacting means for~ no part of the i.nvention ~
and may be any conventional means such as that described in :
U.S. Patent ~OSn 3,825,102 issued July 23, 1974 and 3,838,764 ~
issued October l, 1974 by the same inventor. ~ :

~'~ dap/ . ~

:~4557~

Tilt bridge 20 is provided with a finger 34 extending laterally toward the platen and also with downwardly extending teeth 36 forming recesses 37 therebetween. A print deflection b:Locking arm 38 is mounted for free rotation about pivot pin 24. Print deflection blocking ann 38 is similarly provided with downwardly extending teeth 40 forming recesses 41 therebetween, and is also provided with a recess 42 and abutment 44. Recess 42 of print deflection blocking arm 38 has a configuration and a dlmension signigi~antly greater than the width of finger 34 of tilt bridge 20 to accept finger 34 extending therethrough so as to accommodate a substantial amoun~ o~
play between print deflection blocking arm 38 and tilt bridge 20. Abutment 44 of print deflection blocking arm 38 extends laterally and upwardly from the print deflection blocking arm and presents an upper surface 45 which is adapted to cooperate with a lower print deflection blocking surface 33 forllle~l by the lower extremities of rotation detent teeth 32 Also shown in ~`igure ~1 is a pivot lever 46 which pivotally supports a detent arm 48 carrying a final tilt positioning detent tooth 50, adapted to cooperate witll teetl1 3~, 40 and recesses 37, 41 of tilt bridge 20 and print deflection blocking am 38. Pivot lever 46, together with detent arm 48 and detent tooth 50, are positioned by conventional means not shown to cooperate with tilt briclge 20 and print deflection blocking arm 38 to accurately finally tilt position and : support type carrier 10 to print a preselected type character 12, as explairl~{l further herein.
Prior to rotational and initial tilt indexing of type carrier 1() and to impacting of the type carrier with the platen, pivot lever 46 1s positioned so that, as shown in Figure 2, detent arm 48 maintains final tilt positioning detent tooth 50 in disengaged or non-contacting relation witl teeth 36, 40 of tilt bridge 20 and print deflection bloc~ing arm 38. In ,, this positlon, print deflection blocking arm 38, due to gravity and to the free pivotal connection around pivot pin 24, rests in a downward or unenga~ed position, with the upper surface 43 of recess 42 of print deflection blocking arm 38 resting on the upper surface 35 of finger 34 of tilt bridge 20.

- 6 ~

1~455'7~

In thls position, teeth 40 of print deflection blocking arm 38 extend into the gaps defined by recesses 37 formed by teeth 36 of tilt bridge 20. Also in this position3 abutment 44 of print deflection blocking arm 38 is lowered out of frictional engagement with lower print deflection blocking surface 33 deined by the lower extremities of rotation detent teeth 32.
In operation, to print a preselected type character, type carrier 10 is rotatively positioned by means not sho~n to present to the face of platen 26 the column of type on which the preselected character is located, Since print deflection blocking arm 38 is in the downward or rest position with upper surface 43 of recess 42 of print deflection blocking arm 38 resting on upper surface 35 of finger 34 of tilt bridge 20, type carrier lO
is free to rotate without frictional engagement between upper surface 45 o~
abutment 44 of prlnt deflection blocking arm 38 and print deflection blocl;ing surface 33 of rotation detent teeth 32.
At the same tirrle, type carrier 10 is tilt positioned to present the row of type on which the preselected character is located to face platen 26 and is then driven forward with impacting force toward tlle platen by ~' arm 22, controlled by means not shown.
-. I During the impacting motion and after type carrier 10 has been positioned to present the preselected character for printing, pivot lever 46 is actuated, carrying detent arm 48 to drive tilt positioning detent tooth ~¦ 50 into recesses 37, 41 formed between teeth 36, 40 of tilt bridge 20 an(l print deflection blocking arm 38, as sllown in Figure 3 Detent tooth 50 ! provides a carrrrrting surface against which teeth 40 of print deflection blocking ~ arrrt 38 ride and are camrned upwardly and outwardly 9 raising print deflection blocking arm 38 so that upper surface 43 of recess 42 of the arm is lifted .oP of its resting position on upper surface 35 of finger 34 of tilt brid~e l 20 and also so that the upper s~rface 45 of abutment 44 of print deflection . i 1'.
blocking arm 38 rests against lower print deflection blocking surface 33 of I rot~tion detent teeth 32, as showrl in Figure 1. In this position, detent .~ ,i ' . .
` .

4~5'~

tooth 50 detains print deflection blocking arm 38 firmly so that a downward tangential escape oi type carrier 10 is reliably prevented during prlnting, Blurring or smearing of the type character is thus prevented Detent tooth 50 has the additional ~unction of finally and precisely positioning the described character in the tiLt direction. If, prior to printing, type carrier 10 is tilted too far so that tilt correction is required in the counterclockwise direction as viewed in Figure 1, detent tooth 50 encounters the appropriate tooth 36 on tilt bridge 20 and tilts the type carrier counterclockwise as pivot lever 46 drives detent tooth 50 into print position. Type carrier 10 will thus be rotated so that blocking surface 33 formed by rotational detent teeth 32 moves down~ardly to meet upper surface 45 of sbutment 44 of print deflection blocking arm 38 being dri~en upwardly by the action oE detent tooth 50 against teeth 40. The type carrier and blocking arm come to rest in the posltion shown in Figures l and 3, with the type carrier finally and precisel~ positioned for printing the deslred ~haracterO
If, however, type carrier 10 is tilted too little 90 that tilt correction i9 required in the clockwise direction, as viewed in Figure l, clockwise po~ltioning of type carrier 10 is effected by the action of detent tooth 50 driving upper surlace 45 of abutment 44 of arm 38 against blocking surface 33 of the type carrier. Ai the type carrier is tilt positioned, tooth 36 of til~ bridge 20 is rotated along with the type carrier, and cmnes to rest against detent tooth 50, as shown ln Figure 3, when the type carrier 1~ correctly tilt positloned to print the desired character. Thus, during final clockwi~e tilt positioning, detent tooth 50 does not encounter teeth 36 of ti}t bridge 20 until the positioning has been completed due to the po~ition of teeth 36 and to the size and configuration of xecesses 37 relative to the size of detent tooth 50.
Once the type character has been printed, detent lever 46 and detent arm 48 are returned to the disengaged positlon, disengaging de~ent tooth 50 from teeth 369 40 of tilt bridge 20 and print defllection blocking &rm 38~ allowing print deflection blocking arm 38 to all t~ the rest position~

Il Ij .

~0~S7~
and disengaging surface 45 of abutmerlt 44 from print deflection blocliingsurface 33 of rotation detent teeth 3~. Thereafter, when a new rotational indexing is performed, there is no friction between print deflection blocliing arm 38 and type carrier 10.
In the embodiment illustrated in Figure 4, abutment 44' of print deflection blocking arm 38' is provided with a dimple or protrusion 57 extending upwardly from upper surface 45' of the abutment for rotational detention of type carrier 10 at a selected column in coopera~ion with rotation detent teeth 32 of the type carri'er and for simllltaneouj print deflection blocking of the type carrier.
In the ernbodiment of Figure 5, abutment 44" of print deflection blocking arm 38" is provided with a ball 54, which protrudes througll the upper surface 45" of abutment 44" through a hole 56 in the abutment. nall 54 is retained in tlle slnall diameter notched hole 56 by a flat sprlllg 58 ~,7hich is fastened as by retaining means 60 to the abutrllellt. Ball 54, similar to the ernbodiment of Figure 4, simultaneously rotationally detents the type carrier in cooperation with rotation detent teeth 32 of the type carrier and blocks downward tangential movement of the type carrier during printing.

;

I CLAIM:

': .

_ 9 _

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a single element printer comprising:
a hollow inverted cup-shaped type carrier having type characters on its outer periphery located in rows and columns, a platen, a tilt bridge axially supporting said type carrier for rotational movement to position a selected column of type characters opposite said platen, said tilt member having detent teeth thereon, support means pivotally supporting said tilt bridge for tilting movement about a tilt axis to position a selected row of type charaters opposite said platen, said support means being movable from a rest position to a printing position to impact a selected type character against said platen, said type carrier on impact experiencing deformation with lower portions tending to move tangentially relative to said platen and support member, said type carrier having a blocking surface located in a radial plane, a blocking arm freely pivotally supported on said tilt axis having a radially extending abutment located opposite the platen and proximately beneath and spaced from said blocking surface for arresting tangential movement of said typehead relative to said platen and relative to said support member on impact of a selected type character against said platen, means on said tilt bridge and said blocking arm for supporting said blocking arm spaced from said blocking surface, said blocking arm having teeth which extend between the detent teeth on said tilt bridge, and tilt detent means movable into engagement with detent teeth on said tilt bridge and teeth of said blocking arm for moving said blocking arm and its abutment into engagement with said blocking surface and for finally tiltably positioning said tilt bridge.

2. In a printer as recited in claim 1, wherein said means on said tilt bridge and said blocking arm comprise a finger on said tilt bridge and a recess formed in said blocking arm for receipt of said finger, said recess having a dimension greater than the width of said finger so as to allow relative movement between said blocking arm and said tilt bridge.

3. In a printer as recited in claim 1, wherein said detent means includes a detent tooth movable to enter between a tooth of said tilt bridge and a tooth of said blocking arm to move said blocking arm abutment into engagement with said block-ing surface and to finally tiltably position said tilt bridge.

5. In a printer as recited in claim 1 wherein said blocking surface on said type carrier is defined by the lower extremities of a plurality of rotational detent teeth formed on said type carrier.

5. In a printer as recited in claim 4 wherein said abutment is provided with a protrusion for rotational detent engagement with the rotational detent teeth of said type carrier.

6. In a printer as recited in claim 5 wherein said protrusion is a dimple formed on the abutment.

7. In a printer as recited in claim 5 wherein said protrusion is the surface of a ball protruding through a hole formed in said abutment.