Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3522903 A
Publication typeGrant
Publication dateAug 4, 1970
Filing dateMar 14, 1968
Priority dateMar 14, 1968
Also published asDE1912199A1, DE1912199B2
Publication numberUS 3522903 A, US 3522903A, US-A-3522903, US3522903 A, US3522903A
InventorsWilliam A Lloyd
Original AssigneeVarian Associates
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Paper strip puller having differentially driven pullers to prevent sluing of the strip
US 3522903 A
Abstract  available in
Images(2)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Aug. 4 ,1910

. w. A. LLOYD 3,522,903 PAPER STRIP LER HAVING DIFFERENTIALLY DRIVEN I PULLERS PREVENT SLUING OF THE STRIP Filed March 14, 1968 2 Sheets-Sheet l mvrsmoa WILLIAMA. LLOYD FIG. I

[77, L ATTORNEY BY i Aug; 4, 11910 Filed March 14, 1968 w. ALLLoYD 3,522,903 PAPER STRIP FULLER HAVING DIFFERENTIALLY DRIVEN PULLERS TO PREVENT SLUING OF THE STRIP 1 2 Sheets-Sheet 2 :n 1 z 1 :1 J r\ l 1 I 7 qw 5% u a I. 2 i;1\ g :N ",8 b i l &..M

co co 40 wvv ' 3 Q. .5 egg w m (0 t V '5 I g (D I f E (o i Yve Ln :7, i

- a .0 Q :2 7; 41 m Q m A a 2 I j as "L N y m Q 5 ,-r' I! .1 I Q N :3 k mm 1 INVENTOR. N- l g 7 WILLIAM A. LLOYD .TIVORNEY U.S. Cl. 226-188 United States Patent 3,522,903 PAPER STRIP PULLER HAVING DIFFERENTIALLY DRIVEN PULLERS TO PREVENT SLUING OF THE STRIP William A. Lloyd, San Jose, Calif., assignor to Varian Associates, Palo Alto, Calif., a corporation of California Filed Mar. 14, 1968, Ser. No. 713,003 Int. Cl. B65h 17/08 6 Claims ABSTRACT OF THE DISCLOSURE An electrographic strip chart recorder is disclosed. The recorder includes a supply roll of electrographic recording paper. A drive roller structure frictionally engages the paper and pulls it from the supply roll past an electrographic recording head which forms electric charge images to be developed upon a charge retentive surface of the paper. The charge image bearing paper is pulled past a toner station which develops the images. The drive roller includes a pair of separately rotatable drive segments disposed at opposite ends of the roller and frictionally engaging opposite side edges of the recording paper. A drive motor drives the separate drive rollers through the intermediary of a diiferential gear train serving to divide the driving force supplied from the motor to the drive rollers such that one of the drive rollers may rotate faster than the other and such that the same pulling tension force is transmitted to opposite side edges of the paper. In this manner, the paper is pulled from the supply roll without sluing the .paper to one side or the other of the drive roller structure.

In one embodiment the differential gear train is contained inside of the drive roller structure, whereas, in a second embodiment, the differential gear train is disposed externally of the drive roller structure.

DESCRIPTION OF THE PRIOR ART Heretofore, electrograhic recorders have been built wherein the electrographic recording paper was pulled past the recording head from a supply roll via the intermediary of a motor driven drive roller structure. An example of such a prior electrographic recorder is disclosed and claimed in US. patent application 661,871 filed Aug. 21, 1967 and assigned to the same assignee as the present invention. In this prior recorder, the drive roller extended laterally of the strip of recording paper and frictionally engaged the recording paper over substantially the entire length of the outer surface of the roller.

The problem with such a prior roller structure is that if for some reason the paper starts to be pulled from the supply roll unevenly the roller will continue to exaggerate this condition causing the paper to slue across the drive roller. This can cause the recorded images on the recording paper to slue to one side or the other of the paper and when the paper is traveling at high rates of speed, as in excess of tens of inches per second, it can result in wrinkling of the paper causing the recording to be improperly recorded or developed or both and can result in a breakdown in the operation of the recorder.

3,522,903 Patented Aug. 4, 1970 ice Therefore, a need exists for an improved paper pulling structure which will cause the paper to be pulled evenly \from the supply roll to prevent a sluing of the paper as pulled from the supply roll.

SUMMARY OF THE PRESENT INVENTION The principal object of the present invention is the provision of an improved apparatus for pulling sheet material from a supply roll.

One feature of the present invention is the provision, in an apparatus for pulling sheet material from a supply roll, of a pair of rotatable drive means engaging the sheet material on opposite sides of the longitudinal center line of the material and including means for proportioning the drive forces applied to said pair of drive means to transmit substantially equal pulling tension forces to the strip of sheet material on opposite sides of its center line, whereby the sheet material is caused to be pulled from the supply roll without sluing same to one side or the other.

Another feature of the present invention is the same as the preceding feature wherein the sheet material is paper and the drive force proportioning means includes a differential gear train having two output drive axles with each of said axles being connected to separate ones of said pair of rotatable drive means for dividing the driving force between the pair of rotatable drive means to transmit the same pulling force to opposite sides of the paper.

Another feature of the present invention is the same as any one or more of the preceding features wherein the pair of rotatable drive means comprises a pair of separately rotatable segments of a roller and wherein the outer surface of the roller is arranged to frictionally engage the paper for pulling same from the supply roll.

Another feature of the present invention is the same as the preceding feature wherein the roller is hollow and the differential gear train is disposed inside the hollow roller structure.

Other features and advantages of the present invention will become apparent upon a perusal of the following specification taken in connection with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to FIG. 1 there is shown an electrographic recorder 1 incorporating features of the present invention. The recorder 1 includes a pair of input terminals 2 and 3 to which an input signal E is applied to be measured and recorded. The input signal is fed to a preamplifier 4 wherein it is amplified and fed to the input of an analog-to-digital converter 5. The analog-to-digital converter tracks the input signal E and produces a binary data output 6 representative of the input signal E The binary output signal is fed to an array of electrographic writing electrodes 7 extending crosswise of an electrographic recording paper 8 having a conductive paper backing and a thin dielectric charge retentive surface facing the array of writing electrodes 7.

A cylindrical frictional drive roller structure 9, more fully described below, frictionally engages the paper 8 and pulls the paper 8 past the array of writing electrodes 7 from a supply roll 11. A takeup roll 12 takes up the recording paper 8 after it has passed over the drive roller 9. Alternatively, the takeup roll 12 may be omitted.

The writing electrode array 7 has one of its electrodes selected and energized by the output of the analog-todigital converter for laying down a line charge image 13 on a charge retentive surface of the recording paper 8. The line charge image 13 is a signal trace representative of the input signal E to be recorded. The signal writing electrodes 7 cooperate with a second channel shaped writing electrode structure 14 disposed on the conductive side of the recording paper 8 and operated at a suitable potential such that the writing potential applied to the selected electrode of the array 7 produces approximately -400 to --900 volts relative to the channel electrode 14.

An electrographic recorder employing an array of writing electrodes energized by the output of an analog-todigital recorder is disclosed and claimed in copending US. application 582,767, filed Sept. 28, 1966 and assigned to the same assignee as the present invention.

An electrographic toner channel 15 is disposed facing the drive roller structure 9. The toner channel 15 includes a toner slot 16 cut through the side wall of the channel facing the roller 9 and has its marginal edges curved to conform to the curved cylindrical surface of the drive roller structure 9.

Liquid electrographic toner (ink) is supplied to the toner channel 15 from a reservoir 17 by means of a liquid toner line 18. A vacuum pump 19 draws a suitable vacuum on the top of the toner channel 15, as of -15 inches of water, by means of a vacuum line 21. The vacuum head drawn on the toner channel 15 causes the liquid toner within the reservoir to be drawn via liquid line 18 into the toner channel to a predetermined level within the toner channel above the toner slot 16. A float valve, not shown, controls the conductance of a vacuum bypass line to the reservoir for maintaining the liquid level within the toner channel 15 at a desired height. A toner channel supplied with a vacuum head and interconnected to a reservoir and including a bypass float control liquid level means is disclosed and claimed in copending US. application 577,443, filed Sept. 6, 1966 and assigned to the same assignee as the present invention.

A spring bias force, schematically indicated by tension spring 23 interconnecting the inking channel 15 and the drive roller 9, causes the drive roller 9 to press the recording paper 8 against the marginal edges of the toner slot to assure formation of the liquid seal therebetween. In this manner, the vacuum head may be pulled on the toner channel 15 to draw the toner into the channel 15 and the toner slot 16. The drive roller structure 9 is rotationally driven by means of a belt 25 and a pair of pulleys 26. Drive pulley 26' is driven from the shaft of a motor 27, only partially shown.

An idler roller 28 is disposed on the charge retentive side of the paper 8 between the recording head 7 and the supply roll 11 to assure that the electrographic paper 8 is properly positioned with respect to the writing array 7 and channel electrode 14. In addition, the idler rollers 28 may be engraved with chart scale indices and supplied with a suitable writing potential for laying down charge images on the recording corresponding to the chart scale indices to be printed thereon.

A pair of idler drive wheels 29 are carried upon an axle 31 extending laterally of the recording paper 8 above the drive roller structure 9. A spring bias force, schematically 4 indicated by tension spring 32, interconnects the idler axle 31 and the axle 33 of the drive roller 9. The spring bias force between the idler rollers 29 and the frictional drive roller 9 causes the paper 8, at its marginal edges, to be sandwiched between the idler rollers 29 and the drive roller 9, thereby assuring a good frictional engagement between the drive roller 9 and the paper for pulling the paper from the supply roll 11.

Referring now to FIG. 2 the cylindrical drive roller structure 9 is shown in greater detail. The drive roller structure 9 includes the main drive axle 33 extending longitudinally of and within the roller structure 9. The axle 33 is captured in bearings 34 at its ends to permit rotation of the drive axle 33. The drive pulley 26 is affixed to the drive axle 33 at one end thereof externally of the drive roller structure 9. The drive roller cylindrical structure 9 includes a pair of outer drive segments 35 and 36, respectively, separately driven from the drive axle 33 via the intermediary of a differential gear train 37. The outer drive segments 35 and 36, respectively, are formed by the outer raised portions of hollow cylindrical drive sleeves 38 and 39 which are each supported from the axle 33 via centrally apertured headers 41 holding centrally disposed axially aligned oil impregnated bushings 42 such that the drive sleeves 38 and 39 are free to rotate relative to the drive axle 33.

The difierential gear train 37 includes a pair of beveled drive gears 43 fixedly secured to the transverse headers 41 at the inner ends of each of the drive sleeves 38 and 39, respectively. A pair of diametrically opposed beveled pinion gears 44 mesh with the drive gears 43 and are carried at the opposite ends of a transverse axle 45 fixedly secured to the drive axle 33. The transverse axle 45 forms a spider of the differential gear train 37.

The differential gear train 37 serves to divide the driving force supplied from the motor via the drive axle 33 between the pair of rotatable drive segments 35 and 36, respectively. The differential gear train 37 also permits one of the drive segments 35 or 36 to turn faster than the other such that the same pulling tension force is transmitted to opposite side edges of the recording paper 8. In other words, if slack develops in the paper at one marginal edge relative to the other marginal edge of the paper, the differential gear train 37 permits the drive roller segment 35 or. 36 which is on the slack side to rotate faster and to take up the slack to produce a uniform pulling tension on the paper at opposite side marginal edges of the paper. This prevents the paper from sluing across the roller structure 9 and assures that the paper will be pulled uniformly from the supply roll 11.

A plurality of idler roller segments 46, perhaps better shown in FIG. 3, are disposed intermediate the outer drive segments 35 and 36, respectively. The idler segments 46 are hollow cylindrical sleeve members having an inside diameter slightly larger than the outside diameter of the drive sleeves 38 and 39, respectively, such that the idler segments are free to rotate independently on the drive sleeves 38 and 39.

The outer surface of the drive roller 9 is formed by a relatively thin layer 47, as of 0.063" thick, of a compressible resilient material having relatively high frictional characteristics for frictionally gripping the paper 8. The outer surface layer 47 should also be chemically inert to the liquid toner. Such a resilient material includes the synthetic elastomers such as polyurethane and neoprene. The compressible resilient characteristic of the outer layer 47 of the drive roller structure 9 facilitates formation of the liquid seal between the paper 8 and the marginal edges of the toner slot 16 and, in addition, permits the drive roller 9 to frictionally engage the surface of the idler rollers 29 at the outer marginal edge of the paper 8 such that the idler rollers 29 can be frictionally driven from the drive roller structure 9, thereby producing a double frictional drive action on the paper 8 which is sandwiched between the drive roller structure 9 and the idler rollers 29.

In a typical example of a drive roller structure 9, such a structure has been employed to pull a wide strip of electrographic paper which is approximately 0.0035" thick at a speed of approximately 150" per second without encountering sluing and wrinkling of the paper 8.

Referring now to FIG. 3 there is shown an alternative paper drive roller structure of the present invention. Drive roller structure 9' of FIG. 3 is similar to that of FIG. 2 except that the differential gear train is disposed externally of the drive roller structure 9'. The drive roller structure 9 of FIG. 3 is especially suited for applications where the drive roller is too small in diameter to house the differential gear train structure 37. In the drive roller structure 9' of FIG. 3, the drive roller segments and 36 together with-the idler roller segments 46 are separately rotatably supported upon an axle 33. A pair of drive pulleys 48 and 49 are fixedly secured to the separate drive rollers 35 and 36, respectively. Drive belts 411 and 52 interconnect the drive pulleys 48 and 49, respectively, with drive pulleys 53 and 54, respectively, which latter pulleys are fixedly secured to outputs drive axles 55 and 56 of the diiferential gear train structure 37. Output axle 55 comprises a sleeve rotatably and con centrically supported with respect to a centrally disposed drive axle 57 which is driven from the motor 27 via pulleys 58 and a drive belt 59. The spider 45 of the differential gear train 37 is fixedly secured to the end of the drive axle 57. Drive axle 57 and output drive axle 56 are rotatably supported at their ends in bearing assemblies 61.

In operation, the roller drive structure 9' of FIG. 3 operates in substantially the same manner as previously described with regard to FIG. 2 to produce a uniform pulling tension on the paper at opposite marginal side edges of the paper.

Although the differentially driven paper pulling drive roller structures 9 and 9' of FIGS. 2 and 3 have been described as employed in an electrographic recorder, this is not a requirement. The paper pulling apparatus of the'present invention may be utilized to advantage wherein it is desired to pull continuous strips of sheet material from a supply roll without encountering sluing of the sheet material as drawn from the supply roll. More particularly, the sheet material need not be paper but may include other types of sheet material such as thin sheets of plastic. In addition, the drive roller structure '9 need not be limited to a frictional engagement with the paper ,or sheet material but may include sprocket type drive wheels wherein the teeth of the sprocket engage a series of perforations distributed along the marginal side edges of the sheet material being drawn from the supply roll. Furthermore, the paper pulling apparatus of the present invention need not be limited in its use with electrographic recorders but may be used with other recorders and printers such as, for example, in electrostatic character printers and electrophotographic imaging devices.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a transport apparatus for pulling a continuous strip of sheet material comprising:

a pair of rotatable drive means for transmitting two pulling tension forces to the strip of sheet material on opposite sides of the longitudinal center line of the strip of sheet material;

means for applying a drive force;

a differential train gear means powered by the means for applying a drive force and having a pair of drive axles one of which is connected to each of the rotatable drive means for permitting one of the rotatable drive means to rotate faster than the other and for proportioning the drive force to transmit substantially equal pulling tension forces to the strip of sheet material on opposite sides of the longitudinal center line to prevent sluing of the sheet material;

the improvement which comprises a roller device for engaging and pulling the strip of sheet material, and the pair of rotatable drive means comprising a pair of separately rotatable segments of the roller device.

2. The apparatus of claim 1 wherein the roller device is hollow and the pair of rotating drive means and the differential gear train means are disposed therein.

3. The apparatus of claim 1 wherein the outer surface of the roller device frictionally engages the strip of sheet material for pulling the sheet material.

4. The apparatus of claim 1 wherein at least one idler segment is provided on the roller 'device which is freely rotatable relaitve to the separately rotatable segments.

5. The apparatus of claim 4 wherein the separately rotatable segments of the roller device are disposed at the opposite ends of the roller device and further wherein at least one idler segment is disposed between the separately rotatable segments.

6. The apparatus of claim 1 including a pair of idler wheels, means for spring biasing the idler wheels toward the separately rotatable segments for sandwiching the sheet material between the separately rotatable segments and the idler wheels to increase the frictional engagement between the separately rotatable segments and the sheet material.

References Cited UNITED STATES PATENTS 3,052,396 9/1962 Butscher 226l92 3,119,537 1/1964 Smits 226-188 X RICHARD A. SCHACHER, Primary Examiner US. Cl. X.R. 226-190,

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3052396 *Mar 13, 1959Sep 4, 1962United States Steel CorpSelf-centering rolls
US3119537 *Jun 27, 1962Jan 28, 1964Smits Robert GMultiple differential rotary mechanical drive
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4527174 *Jun 23, 1983Jul 2, 1985Alps Electric Co., Ltd.Sheet pressing mechanism in a pen type recording device
US4538516 *Aug 13, 1981Sep 3, 1985Somerset Technologies, Inc.Torque-assist system for printing belts
US4863085 *May 29, 1987Sep 5, 1989Noritsu Kenkyu Center Co., Ltd.Apparatus for transporting a strip of photographic printing paper in a printer
US9403652Jan 13, 2011Aug 2, 2016Hewlett-Packard Development Company, L.P.Spindle
US20110017082 *Jan 27, 2011Raimon CastellsPrinting system
WO2000069764A1 *May 9, 2000Nov 23, 2000Kern AgDevice for processing strips of forms
Classifications
U.S. Classification226/188, 226/195, 346/136, 400/579, 226/190
International ClassificationG01D15/24, B65H16/10, B65H23/038, G01D15/28, B65H20/02, E04C2/08
Cooperative ClassificationG01D15/24, E04C2/08, B65H20/02, B65H2404/13211, G01D15/28
European ClassificationB65H20/02, E04C2/08, G01D15/24, G01D15/28