CA1104874A - Print band support mechanism - Google Patents

Abstract

Abstract of the Disclosure A print band is trained around a drive pulley and an idler pulley, the pulleys being spaced apart to provide a band path therebetween and along a printing station. The drive pulley is supported in fixed position whereas the idler pulley is supported in a cradle by resilient means to permit the idler pulley to move toward and away from the drive pulley.
Such movement is accomplished by a cam member axially fixed in position and rotatable to move the idler pulley support cradle to and from the drive pulley. A pair of edge guide rollers and a pair of flexible levers act as limits when loading the band on the pulleys.

Description

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In the field of hlgh speed prlnters 9 the drum printer has proved to be very suecessEul ln provldlng a rotating surface agalnst which print hammers lmpact the characters carried on such surface. Hcwever, the need for a reduction in weight along with compactness in size and decrease in C05t has brought about the endless print band which carrie~ the type characters in a line along the print station and past the print hammers. Such print han~lers are constructed in a bank which includes hammer drive solenoids for causing the hammers to be driven ag~inst the type characters on the band in a sequence dictated by the desired printing program.
The prin~ band i8 trained around a drive pulley and a drlven or idl~r pulley normally in horizontal manner, such pulleys being crowned to provide a tracking surface for the band. Provisions may also be made in th~ suppor~ing structure for the pulleys to permit rapid changing of the print bands while at the s~me time maintaining proper tension on the band during operation.
Representative prior art relating to the sub~ect matter o~ the present invention is disclo~ed in United States patent No. 3~362,325, issued on January 9, 1968 to W. P. Fo~ter, wherein an endlass belt mask i9 ~ournaled around a driving pulley and a driLven~pulley, the driven pulley being mounted on ;

a spring loaded V-shaped base. ~ pair of support rods span the base and springs nn the support rods along with ad~ustlng mean~

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provide bias and displacement oE on~ pulley from the oth~r pulley. United States patent No. 3,955,500, i~sued on May 11, 1976 to F. A. Mahoney et al., diLscloses type band idler pulley mechanism wherein the idler pul.Ley is supported from a trolley carrled by a pair of r~ . Sprlngs on the rails between the trolley and retaining rings maintain a predetermlned force on the band and notches in the rails for the retaining rings enable different size bands to be used.
Summary_of the Inventlon The present invention relates to band printers and more particularly to support means for an erldless band contain-ing type characters on the circumference thereof. A motor drives one pulley which is in a fixed position, such pulley be-ing referred to as the drive pulley and around which the endless band is trained. A second or idler pulley is spaced from the drive pulley and is supported in a cradle carried on resllient member~ which permlt the idler pulley to be moved toward and away from the drive pulley. The cradle 1~ U-shaped and is urged in a direction away~fr~m the drlve pulley by a spring which cooperates wlth a cam m~mber in positloning ~he ldler pulley in a flrst or a second po9it~0n when changing the type charaeter endless band. The assembly of drive and driven pulleys, the prin~ band, and assocLated supporting mem~er~ are carried in a gate structure whLch is swingable at one end thereof from an operating positLon wherein the print band is ad~acent the b~nk of hammers to a~n:open po~ition or lvading paper in~o the printer

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or for loading a print band on the pulleys. The gate structure also includes a pair of guide rollers and a pair o~ flexible levers which are contacted by one edge of the print band when loading the band on the pulleys to properly position the band along a line cooperable with the line of impact of the print hammer against the type characters on the print band.
In accordance with the invention there is provided support means for an idler member of a drive system having a drive member swpported for rotation about and movement longitudinally on a fixed axis and spaced from said idler member, and an endless band trained around said idler member and sald dri~e member, said support means including a cradle frame member rotat-ably supporting said idler member; spaced apart ~ springs parallel to said 1'"'`~
axis and substantially equal in length resiliently supporting said cradle frame member enabling movement of said idler member in a direction toward and a~ay~rom said drive mem~er; rotatable camming means operably connected with ~ald cradle .frame member for causing movement of said idler member a pre-determined distance in the direction toward said drive member; and spring ~eans aligned with said idler member and with said drive member and engageable ~th said rotatable camming means and with said cradle frame member for bias-lng said idler member in the direction away from said drive member.
: 20 In accordance with another aspect of the invention there is pro-Yided in a printer having a gate structure, a drive member supported for rotation about and movement longitudinally on an axis fixed with respect to said gate structure, an idler member spaced from said drive member, an end-less type character carrier trained around said drive member and said idler member, and means supporting said idler member including a cradle frame mem-ber supporting said idler member for rotation about an idler axis; spaced a-part leaf springs parallel to said idler axis and connected with said gate tructure or resiliently supportlng said cradle frame member enabling~move-ment ~ said idler member in a direction toward and away from said drive ~.
~eMfier; camming means connected with said gate structure and with said cradle ~:
rame member for moving said idler member in the direction toward said drive member upon rotation of said camming means; and spring means positioned be ~ `
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tween said drive member and said idler member and engageable with said camming means and with said cradle Erame member for biasing said idler member in a direction away from said drive member.
In accordance with the above discussion) the principal object of the present invention is to provide means permitting the prin-t band to be easily changed.
Another object of the present :invention is to provide means ac-commodating variations in print band length.
An additional object of the present invention is to provide means which will tolerate pulley runout.
A further object of the present invention is to provide means for maintaining uniform tenslon in the print band.
Additional advantages and features of the present invention will be-come apparent and Eully understood from a reading of the following descrip-; tion taken together with the annexed drawings, in which:
Figure 1 is a perspective view of a portion of a printer in-corporating the subject matter of the present invention;
Figure 2 is a plan view of the print band gate structure including the drive and driven pulleys with the print band trained therearound;
~igure 3 is an elevational view of the print band gate structure shown in Pigure 2, with portions removed therefrom and r 4a ~

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showing the resllient support members for the driven pulley;
F~. 4 is an enlarged v~w of the driven pulley support members;
Fig. S is An elevatlGrlAl view o the print band and associated apparatus, taken along the llne of printing; ~nd Fig. 6 is an enlarged, exploded view of the cam s~ructure for positioning the drlven pulley.
As seen in Fig. 1, a printer incorporatlng the sub-Ject matter of the present invention utilize3 a b~nd for carrying the type characters thereon, such band printer distin-guishing from a drum printer in a number of area~ ~nd features, the most significant area being the type carrying structure.
The prlnter lO, of course9 includes the framework of vertical side plates 12 and 14~ which support the print band gate structure 16, the hammer bank 18, the paper forms tractors 20 and 22 carried o~ shafts 24 and 26, the power supply and servo drlve 289 and other major parts whlch wil~ be explained in further detail hereinafter. An on-off switch 30 is located ~t the lower right ~ront of the printer, a start-stop switch 32 and a ~orms eed swltch 34 are positioned un the top right front o~ the printer, and forms handling control mechanism 36 is located on l:~e left slde of the printer. A transformer 3 and a blower unit 40 are disposed ~nder the gate struc~ur~ 16~
the blower unil: pro~iding cooling to the various areas snd parts ; of ~he printer., Fonm paper or like record media 41 i8 caused ~o be ~: - 5 -~: :
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driven or pulled by the tractors 20, 22 from a forms stack below the gate structure 16, upwardly past the printing station be-tween a type band 54 and the hammer bank 18, and out an exit slot at the rear of the printer. A ribbon (not shown in Figure 1) is caused to be driven from a ribbon spool rotatable on the spindle 42 which is supported on a frame member 44 and driven by a motor 46 located at the left side of the gate structure 16, the ribbon being guided in a path rearward of the gate structure and onto a ribbon spool rotatable on a splndle 48 which is supported on a frame member 50 and driven by a motor 52 at the right side of the gate structure.
The print or type band 54 is caused to be rotated in a counter-clockwise direction by the drive pulley 56, at the left side of the gate structure 16~ and around a driven or idler pulley 58 located at the right side of the structure 16, the band 54 being directed in a path adjacent a platen (not .~ shown in~Figure 1) and past a print station and positioned to be impacted by hammers aligned in a horizontal manner forward of the hammer bank 18. A hammer bank drive motor 60 is provided for driving or moving the hammer bank in a horizontal direction for purposes not relevant to the subject matter of the present invention.

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In Figure 2 is shown a plan view of the gate st:ruc-ture 16 with certa:in portions removed, and ln Figure 3 is an eleva-tional view of the gate structure, partly in cross section to better show the parts of the invention, such structure including an enclosed framework 70 supporting a mo-tor 72 having a drive shaft 7~ for rotating a pulley 76 about which a belt 78 is trained for driving a pulley 80 on a shaft 82 supported from and journaled in suitable bearings in the framework 70 and in an upper frame member 8~ and causing rotation of the drive pulley 56 about which the print band 5~ is trained. Such print band 5~ is of the endless belt type and, as mentioned above, follows a path adjacent the platen and past the print station : where the hammers 86 impact aganst the characters on the band.
The drive pulley 56 is fixed in location but the driven or idler pulley 58 is supported in a manner to be movable in a direction toward and away from the drive pulley 56 as explained hereinafter. As illustrated in Figure 3, pulley 56 is supported on a light spring 88 so as to assume a floating position axially : with respect to the shaft 82, such pulley 56 being also crowned ~ 20 to provide proper tracking of the band in relation to the - supports and guiding devices therefor.
The idler pulley 58 is carried on a shaft 90 which is journaled in suitable bearings 89 and 91 in a U-shaped frame member or cradle 92 which is secured to a pair of spring-].ike or flexlble leaP sprin~ supporting members 9~ and 9~ which _ 7 _ . ' ~

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extencl upwardly fram a 1~7er portion of the gate structure framework 70, such u~7ar~1y extending supportlng members 94 and 96 being ~jolne~ by sultable means to a b~se member 98 secured to such l~wer portlon of the structure 70 and ~he upper ends of the members 94 and 96 being secured to opposite ends of the cradle 92. Such spring-like memkers 94 and 9S are qpaeed frcm each other and provide the sole support for the cradle 92 ~nd hence the idler pulley 58, and allow the cradle ~12 to move in the di-rection of ~he phantom lines as sh~wn in Fig. 4. The U-8hap~d 10 member or cradle 92 is open at one side thereof to permi~ load-ing and unloading of the prlnt band 54. As a eature of the invention, the leaf springs 94 and 96 provide the first portion of structure which permits or enables the idler pulley 58 to ~nove toward and from the drive pulley 56. The axis of the idler pulley shaft 90 remains parallel to its original position (that shown by the solid line illustration of the cradle 92 and the supporting members 94 and 96 in Fig. 4) while being subjected to horizontal motion or dlsplaced from the original position as shown in expanded form by the phantom lines in Fig. 4. The ~mall 20 vertieal displacement of the crsdle 92 resulting from the horl-zontal mot~on has no ~ertic~al effect on the pulley system sin~e the pulley 56 iB9 in effect, floatlng and is dependent upon ;: certaln guide means ~or retaining the b~nd 54 in a vertical posi-tion during ~ts, travel past the print ha~er~ 86. In this manner, : ~he idler pulley 58 remains aligned with the drive pulley 56.
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In Fig. S ~is; sh~owN a s~de vlew o the llne up o the , :`

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associated parts at the printillg station wherein a platen 110 is supported frc~ the gate structure framework 70~ A tape 112 i9 located adjacent the pla~en llO to provide a bearing surface for the print band 54 as it travels past the platen 1109 the print ba~d having type characters 114 thereon in raised surface manner. An ink ribbon 116 is caused to be driven in a path ad~acent the print band 54 and a ribbon shield 118 is supported between the ribbon 116 and the form paper 120, the shield having an elongated slot therein corresponding to the position of ~he line of print hammers 86. Such ribbon shield 118 provides protection ~or the paper 120 from the ink ribbon 116 upon i~pact of the hammers 86 agalnst the type characters 114.
Means is also provided for ease in changing the print band 54 wherein the tension on the band is released and the idler pulley 58 is moved in a direction toward the drive pulley 5S. Assuming that a band 54 is to be installed or loaded on the mschine, the gate structure framawork 7V is placed or swung ! ~ into an open position (as shown by the phantom lines in Fig. 23 by means of a pivot 122 wherein the print station is freely accessibIe therefor as well as for loading the form paper 120 on the drive tractors 20 and 22~ With the gate structure framework 70 in t~e open po~ition, a release lever 124 (Flgs. 2 . ~ and 3) is swung nlnety degree~ about a pivot pin 126 supported from a sub-structure 128 of the gate structure framework 70, ~ .
As seen more clearly ln Fig, 6" the pivot pin I26 is journaled in the sub-struc~ure 128 and includes a cam surface 130 on one , . ..

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side thereof in extended n~anner for eng~gement with and operat-ing in a bore 131 of a T-shapPd bushing member 132 which lncludes an ad~usting screw m~mber 134 about whLch ~ spring 136 is placed for exerting compression between an end portion 133 of the cradle g~, and a si.de port:ion of the bushing member 132, thereby urging the ldler pulley 58 ln fl direction away ~rom the drive pulley 56 (to the left in F`ig. 3). A bearing plate 135 for one end of the spring 136 ls secured to the end portion 133 of the cradle 92 by suitable means and such plate ha~ an apert~re therein for passage of the screw member 134. When the release lever 124 i~ turned or rokated 90 degrees ~Fig. 2), the bushing member 132 is caused to be moved to the ri~ht (Fig. 3) by reason of the camming action of the surface 130 in the bore 131 and along with release of pressure on the spr1ng 136~ the cradle 92 is caused to be moved to the right on itssupporting spring members 94 and 96. Another feature of the invention is the cammlng means which provide~ the second portion of the structure which positively cau~es the idler pulley 58 to mo~e toward and away fram the drive pulley 56. This slight displace-.
ment of the cr~dle 92 tb the phantom line positlon of Fig. 49~long with the idler pulley 58 carried thereby, permits the operator ~o easily load the print:band 54 on ~he drive pulley 56 and on the icller pulley 58. The extended or enlarged portion :` of the cam surface 130 rotates and operate~ within th~ bore 131 of the member 132 to move t:he cradle 92 from the ~o~id line or first posltion ~howlng in Fig. 4 to the phantom line or sero:nd :

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position showing ~nd return. The ~crew member 134 also providee for adjusting the precise position of the cradle 92 ~n relation to the plvot pin 126 to all~w for slight variatlons in length of dlfferent print bands.
Means is also provlde~ for assurlng that the print band 54 is properly placed or positioned when loading such band on the pulleys 56 and 58. As ilLustrated in Figs. 2 and 3, a ~: pair of ed~e guide rollers 140 and 142 are ~ournaled ln one side of the gate structure framework 70 (opposlte from the print station) to provi~e a support and guide for the print band edge along one side of the gate structure. A palr Gf resilient levers 144 and 146 are secured to the ga~e structure framework 70 on the print station side thereof ~Fig. 2), the levers being formed so as to be normally bowed into an open position (see the phantom showing in Fig. 2)~ such positlon of the levers providing a support or limit for the edge of the print band 54 when loadLng thereof, With the 1ower edge of the print band 54 in contact with the edge guide rollers 140 and 142, and in con-tact with the top surface of the levers 144 and 146 along the prin~ statlon s:Lde of the gate structure9 the release lever 1~4 is rotated 90 degrees to mo~e the cradla 92 and the idler pulley ., ,; 58 toward:the left to ~ension the print band 54 for the : operating condil:ion. Frame members 148 and 150 of the printer are engage~ by t:he levers 144 and 146 when the ~ate str~cture 16 .
~: is swung to the closed posltion~ thereby causing such levers to :be straightened~ as shown ln ull lines in Fig. 2, to ~ positlon ~, :

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free and clear of engagement with the prlnt band 54. When the printer 10 is operating~ there i9 a slight clearance between the lower edge of the print band 54 and the top surface of the levers 144 and 1469 as seen in Fig. 5.
It is thus seen that herein shown and described i6 a print band support mechani6m or as~embly which provide~
structure for the drive pulley and the idler pulley to enable simple loading of the print band7 to AllGw for var~atlons ln band length, and to provlde for uniform band tension. The idler pulley is supported frGm fl~xible members to allow such idler pulley to mo~e toward and away from the drive pulley, and the camming means provldes the positive action to causQ such mo~e-ment for the intended puryose. The apparatu~ enables the accomplishment of the ob~ects and advantages mentioned above, a~d while only one embodiment of the invention has been disclosed herein9 variations thereof may occur to those skLlled in the art. It is thus contemplated that all such varia~ions, not departing from the spirit and scope o~ the inven~ion hereof, are to be construed;ln accordance with the following claims.

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Claims (10)

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

1. Support means for an idler member of a drive system having a drive member supported for rotation about and movement longitudinally on a fixed axis and spaced from said idler member, and an endless band trained around said idler member and said drive member, said support means including a cradle frame member rotatably supporting said idler member; spaced apart leaf springs parallel to said axis and substantially equal in length re-siliently supporting said cradle frame member enabling movement of said idler member in a direction toward and away from said drive member; rotatable cam-ming means operably connected with said cradle frame member for causing move-ment of said idler member a predetermined distance in the direction toward said drive member; and spring means aligned with said idler member and with said drive member and engageable with said rotatable camming means and with said cradle frame member for biasing said idler member in the direction away from said drive member.

2. The support means of Claim 1 wherein said frame member is U-shaped to define an opening permitting removal of said band from said idler member.

3. The support means of Claim 1 including guide means for supporting said band independently of said drive member and idler member.

4 In a printer having a gate structure, a drive member supported for rotation about and movement longitudinally on an axis fixed with respect to said gate structure, an idler member spaced from said drive member, an end-less type character carrier trained around said drive member and said idler member, and means supporting said idler member including a cradle frame member supporting said idler member for rotation about an idler axis; spaced apart leaf springs parallel to said idler axis and connected with said gate structure for resiliently supporting g said cradle frame member enabling move-ment of said idler member in a direction toward and away from said drive mem-ber; camming means connected with said gate structure and with said cradle frame member for moving said idler member in the direction toward said drive member upon rotation of said camming means; and spring means positioned be-tween said drive member and said idler member and engageable with said camming means and with said cradle frame member for biasing said idler member in a direction away from said drive member.

5. In the printer of Claim 4 wherein said drive and idler members are pulleys and said carrier is a band having type characters thereon.

6. In the printer of Claim 4 including guide means for supporting said band independently of said drive member and idler member.

7. In a printer having a type character carrying structure pivotally supported therefrom and including a drive pulley and a driven pulley with a type character band trained around the pulleys, a plurality of hammers adapted to impact against the type characters in printing operations; a guide means for supporting said type character band and maintaining its position with respect to said hammers independently of said drive pulley and driven pulley;
cradle means for journaling said driven pulley for rotation about an axis;
parallel spaced apart leaf springs connected with said type character carry-ing structure and with said cradle means for resiliently supporting said cradle means to enable linear movement of said driven pulley in a direction toward and away from said drive pulley; camming means connected with said type character carrying structure and with said cradle means for moving said driven pulley in the direction toward said drive pulley, and spring means linearly positioned between said drive pulley and said driven pulley and en-gageable with said cradle means and with said camming means for biasing said driven pulley in the direction away from said drive pulley.

8, In the printer of Claim 7 including pivot means permitting swinging of said type character carrying structure from said plurality of hammers for permitting removal of said band from said drive and said driven pulleys.

9. In the printer of Claim 7 wherein said drive pulley is mounted for rotation about and movement longitudinally on a fixed drive axis.

10. In the printer of Claim 7 including a cradle member supported from said type character carrying structure for journaling said driven pulley.