US3739648A

US3739648A - Roller band reciprocating drive mechanism

Info

Publication number: US3739648A
Application number: US00145653A
Authority: US
Inventors: M Payst
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1971-05-21
Filing date: 1971-05-21
Publication date: 1973-06-19
Anticipated expiration: 1990-06-19

Abstract

A drive mechanism for converting small amplitude linear motion of a driving member into large amplitude linear rolling motion of a driven element is disclosed. The drive mechanism consists of an improved roller band, or ''''rolamite'''' device which has a pivotable roller guide member and a resiliently tensioned band.

Description

[ June 19, 1973 United States Patent 1 Payst ROLLER BAND RECIPROCATING DRIVE OTHER PUBLICATIONS MECHANISM D. F. Wilkes; Rolamite: A New Mechanical Des ign [75] Inventor: Michael W. Payst, Raleigh, N.C.

Concept; Sandia Laboratory Research Report SC RR 67 656 October, 1967 Pages 36, 108, 70, 111, 113, 124 and 160 22 Filed:

Primary Examiner-Charles J. Myhre [21] Appl. No.: 145,653

Assistant ExaminerWesley S. Ratliff, Jr. AttorneyHanifin and Jancin and Edward H. Duffield [57] ABSTRACT A drive mechanism for converting small amplitude linear motion of a driving member into large amplitude linear rolling motion of a driven element is disclosed.

Field of Search [56] References Cited UNITED STATES PATENTS The drive mechanism consists of an improved roller band, or rolamite device which has a pivotable roller guide member and a resiliently tensioned band.

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INVENTOR MICHAEL W. PAYST BMW AGENT ROLLER BAND RECIPROCATING DRIVE MECHANISM BACKGROUND form linear reciprocating motion in one plane into linear reciprocation in another plane, these devices have generally employed linkages, pushers and rocker arms, cranks and connecting rods or gears, all of which are more cumbersome and complicated to build and are less efficient than a roller band device which eliminates nearly all but rolling friction. Similarly, while roller band devices of other types have been developed, they have not been adapted to produce large amplitude linear driven motion in response to small amplitude linear driving input. Also, while these prior art devices have functioned for their intended purposes, they have all, with the exception of roller band devices, been bulkier, less efficient and far more complicated in structure. Therefore, these devices are more expensive to build and maintain and they are less easily adapted to suit a wide variety of applications.

OBJECTS It is an object of this invention to provide an improved traversing drive apparatus which has very low frictional losses.

It is a further object of this invention to produce a large linear motion of a driven member from a relatively small linear motion of a driving memberina new and improved fashion.

It is still a further object of this invention to move a scanning head across a line of data bearing material in an improved manner with a minimum of mechanical complexity.

It is also an object of this invention to provide a reciprocating drive apparatus of an improved structure which is easily adaptable to a wide variety of applications.

SUMMARY This invention improves on known types of rolamite or roller band devices by combining the effects of two elements. First, as has been known in the prior art, the roller band itself is resiliently tensioned to allow for increasing the amount of wrap of the. band about the roller members. The resilient tensioning of the band member also provides the motive force for drawing the rolling members and the scanning head, orother load attached to the rollers, back and forth across the length of the guideways to perform useful work. It also takes up the slack in the band produced by the changes which take place in the relative spacing between the roller members as they traverse the length of the guideways.

Secondly, the addition of a pivoting .or movable guideway provides a means for changing the interguideway spacing to bias the direction of travel of the roller members in one direction of the other. While this feature has been separately known in the prior art, it is new in the art to utilize a movable guideway as a means for initiating motion of i the roller members from one end of the guideways to the other. Furthermore, the resilient tensioning mount, when combined with the pivoting guide, not only provides a means for moving the rollers along the guideways with greater force, but it also provides a return or restoring force to move the roller members and any load attached thereto back to the starting position. This is a new result in the art of roller band devices in general.

DRAWINGS FIG. 1 illustrates a simplified embodiment of the present invention in which the movable guideway and resilient band tensioning members are clearly shown.

FIG. 2 is an illustration of the action produced by moving the movable guideway to a position parallel to the other guideway.

FIG. 3 illustrates, in dashed lines, the action produced by depressing the movable guideway still further and it also shows, in solid lines, the resting position of the roller band and rollers when a movable guide is held in its fully depressed position.

FIG. 4 illustrates an embodiment of the invention which incorporates a scanning head and mounting apparatus for the scanning head.

FIG. 5 illustrates one means for driving the movable guideway.

FIG. 6 illustrates another means for driving the movable guideway.

FIG. 7 illustrates another embodiment of scanner similar to FIG. 4 but having a scanning head which rotates with the roller to which it is attached.

FIG. 7 also illustrates how one of the rotatable members may be provided with end flanges for guiding it along the guideway and for keeping the other rotatable member in alignment therewith.

One embodiment of my invention is shown in FIGS. 1, 2 and 3. In these figures a roller band reciprocating drive mechanism having a flexible band 3 is shown with the band looped in a general S shape about rotatable members 1 and 2. Guidewalls or

guideways

4 and 5 enclose the flexible band and the rotatable members within a space which is not wider than the combined cross-sectional demensions of the rotatable members with the flexible band wrapped about then as shown. Guideway 4 is shown as being pivotally mounted in mount 6 by pin 7 to provide for convergent or divergent movement of guideway 4 with relationship to guideway 5. Mount 6 also serves to stop the motion of the roller cluster and band when they reach the limit of travel in that direction. At the opposite end of

guideways

4 and ,5, end piece 8 restrains the pivotal motion of guideway4 so that the spacing between

guideways

4 and 5 does not exceed the dimension previously specified. Italso serves as a stop to halt the motion of the roller cluster and band.

End 9 of flexible band 3 issecured to guideway 5 by screw means 10, but any suitable fastening device could be used. Opposite end 11 of band 3 is provided with a resilient tensioning means 12 in the form of a helical spring. It is necessary that end 11 be resiliently tensioned to allow for the increased wrapping of flexible band 3 about rotatable members 1 and 2 when movable guideway 4 is moved convergently toward guideway 5. It also serves to take up the slack generated in flexible band 3 when movable guideway 4 is moved divergently with respect to guideway 5. The resilient tensioning means 12 also provides force which acts through the flexible band to move rotatable members 1 and 2 back and forth between

guideways

4 and 5 together with any load which may be attached to rotatable members 1 and 2.

The embodiment shown in FIG. 4 is similar in most respects to that shown in FIGS. 1 through 3 with the exception that drive link pin 13 is inserted in rotatable member 2 so that the translational motion of rotatable member 2 can be imparted to scanning head 14 attached to pin 13. Both embodiments operate in the same manner as will be described further below.

With the exception of a small amount of sliding contact between band 3 and guideway 4 and band 3 and end piece 8, during the initial depression of guideway 4 into convergence with guideway 5, the movement of the rotatable members and the loop in the deformed band from one end of the guideways to the other is characterized by strictly rolling contact of exceedingly low frictional resistance. Of course, the hardness and surface finish of the materials of the guideways, rollers and band affect the amount of friction and the ease with which rolling contact between the various members is initiated and maintained. To the end that friction may be reduced to a minimum, the materials of

guideways

4 and 5, rotatable members 1 and 2 and band 3 should be relatively hard, such as steel, and provided with smooth surface finishes. The small initial sliding friction could be overcome by placing some smaller rollers at the points of contact, but nearly flush with the surfaces of guideway 4 and end piece 8.

FIGS. 4 and 7 show two more embodiments of my invention as adapted to provide a controlled speed, bidi rectional scanning drive in a data scanner. in FIG. 4, a data scanning head 14, which may be magnetic, optical or electrical, is attached to roller 2 by a link pin 13 for reciprocation with roller 2. In this embodiment, means are further provided by way of guide pins 17, guide member 15 and guideslot 16 to prevent rotation of the scanner head with roller 2. However, as shown in FIG. 7, another embodiment of a scanner can be utilized in which the scanning head is rotated by roller 2. Either scanner embodiment takes full advantage of my improved drive mechanism to achieve controlled, relatively long sweeps back and forth across a data medium.

As shown in FIG. 7, end flanges 18 may be added to roller 1 to guide roller 1 along guidewall 4 and to keep roller 2 and band 3 in alignment with roller 1 and the guideways.

OPERATION Transverse motion of rotatable members 1 and 2 from one end of the guideway configuration to the other is initiated as shown in FIG. 2 by applying a force tending to move movable guideway 4 into convergence with guideway 5. The angle A, shown in FIG. 1, depicts the angle which a line joining the centers of rotatable members 1 and 2 makes with a fixed horizontal line prior to the depression of movable guideway 4. As shown in FIG. 2, angle A is reduced to angle B when guideway 4 is parallel to guideway 5, and a greater portion of band 3 is wrapped around rotatable members 1 and 2. This is accompanied by a deflection and increase in length of resilient tensioning means 12 as shown. In FIG. 3, the dotted or dashed line running vertically through the upper guide member and band indicates the point of furthest extension of the tensioning means 12 when the upper guide is fully depressed into maximum convergence illustrated in phantom at the right of FIG. 3. The final position in FIG. 3 of the end of the band 3 is as depicted and, it will be noted, this position is still somewhat to the right of the least energy position shown for the end of band 3 in FIG. 1. The extension of spring 12 from its position of least energy in FIG. 1 through elongation in FIG. 2 to its maximum expansion illustrated by the dotted line in FIG. 3 is intended to illustrate the extensible resilient tensioning just described. Continued depression of movable guideway 4 results in a further decrease of the angle B until the angle C shown in phantom lines in FIG. 3 is reached. At that point, rotatable members 1 and 2, under the urging of resilient tensioning means 12 and the inherent resiliency of deformed band 3, tend to move to the left as shown to reach a less highly stressed, or lower energy, position as shown at the left of FIG. 3. The ending position of rotatable members 1 and 2 in FIG. 3 is characterized by angle D which is greater than angle C but less than angle B. It also shows the return of end 11 partially towards its original undeflected position due to the decreased amount of wrap of band 3 about rotatable members 1 and 2. If the configuration shown in FIG. 3 is released, i.e., if the depressing force on the opposite end of movable guideway 4 is released, the guideway will move to its upward or diverging relationship as shown in FIG. 1 and the rotatable members will move to the position shown in FIG. 1 following the same combined rolling and sliding mode of translation as that which occurred in FIG. 3 just described. This is the lowest energy or least stressed configuration.

A full discussion of the physical phenomena which are operative in roller band devices in general will be found in Atomic Energy Commission Document SC- RR-67-656B, by D. F. Wilkes. As taught therein, it is clear that many modifications in the flexible band, in its material, configuration and in its tension, can be made in order to vary the amount of force which is required to cause the rotatable members to translate along the guideways; and conversely, the amount of force which they will exert on a load attached to the rotatable members as they move along the guideways. Similarly, mahy other changes may be made as taught therein in the configuration of the rotatable members, their numbers and in the stopping means or blocks at either end of the guideways without changing the basic mode of operation of my invention. It would, thus, be obvious to one of ordinary skill, when using the teachings of Wilkes, to construct my invention in other configurations to achieve different force and travel characteristics without departing from by basic contributions of the combined movable guideway and resilient band tensioning features which allow the use of a roller band device as a linear drive mechanism.

Any suitable means for applying a force to the nonpivoted end of the movable guideway, such as an eccentric cam or a reciprocating plunger or even the application of pressure by hand would achieve the same result. Similarly, any suitable means of mounting at least one guideway for convergent and divergent movement with relationship to the other guideway will satisfactorily achieve the result when applied in combination with the resilient tensing means. The resilient tensioning means may also be in a variety of forms, such as, for instance, a weight and cable instead of a helical spring. It is not necessary that one guideway be fixed, for both could be made pivotal or given a degree of freedom to move with relationship to each other as taught herein since the resulting convergent and divergent relationship is the same regardless of whether or not both guideways moves with respect to the other. All that is required is that the guideways converge and diverge alternately under the influence of some external driving force to produce the linear translation of the rotatable members and any load attached thereto.

As used herein, the terms convergent and divergent mean that the guideways will converge and diverge alternately when viewed from a point at which the moving force is applied to one of the movable guideways and looking toward the point at which pivoting occurs with respect to one or both movable guideways. Stated simply, this means that the point of convergence (or divergence) between the guideways will move from a location towards one end of the guideways to a location toward the other end. This is clearly shown in FIGS. 1 through 3 where the point of convergence between the guideways moves from a position toward the left hand side in FIG. 1 to a position towards the right hand side in FIG. 3 due to the application of force F as shown in FIGS. 2 and 3. This action creates one-half of a full reciprocation of rotatable members 1 and 2 from one end of the

guideways

4 and 5 to the other. Upon release of the force F, the geometry is reversed to create the other half of a full reciprocation as discussed above. It can thus be seen that looking at either given end of the guideways, alternate convergence and divergence will be seen to exist at that end during a full reciprocation of the rotatable members.

As used herein, the term rolamite is taken to comprehend a relatively new mechanism already developed in the art, which includes a group or pair of adjacent rotatable members or rollers which are supported between spaced surfaces or walls of a guideway by a flexible tension band or ribbon to form a stable or locked, free-rolling roller band cluster. The band extends in a generally S-shaped configuration partially around the rotatable members and may be held under tension by suitable fasteners, such as screws or bolts, which attach or fasten the band ends at opposite extremities and on opposing walls of the guideway. The summation of the diameters of the rotatable members is at least slightly greater than the distance between walls of the guideway so as to maintain a locked or stable, rollerband cluster. The band tension produces a torque which urges the rotatable members firmly toward their respective restraining walls and holds their axes parallel to each other, the combined effect of band tension and restraining walls being to urge the rollers toward each other.

ADVANTAGES My invention has .many advantages over the devices known in the prior art, but chief among them are the following:

It provides a simple, rugged, reliable and easily constructed linear actuator which is quickly adaptable to a wide variety of linear traverse applications, including the application to a scanning device, as shown herein.

It is compatible with a great variety of power actuation means for driving the movable guideway, such as cams, pushrods, hand pressure and the like which are generally easily installed in most mechanical and tromechanical devices.

It requires little or no lubrication, is easily cleaned, and can be adapted to provide a wide range of load and distance traverse variations without changing the basic power actuator.

It can be cheaply made and has a long life since there is little wear produced by its operation. It can be made of a variety of materials.

While this invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In a rolamite device having a plurality of rotatable members, a tension band looped about said members, and guideways confining said rotatable members and tension band, the improvement creating a reciprocating drive mechanism therefrom comprising, in combination:

means for mounting at least one of the guideways for elecconvergent and divergent movement with respect to the other guideway in response to a motive force;

means for applying a motive force to said movable guideway to cause it to alternately converge and diverge with respect to the other guideway; and

extensible resilient support and tensioning means affixed to one end of said band for resiliently holding said band in tension and to take up the slack produced in said band due to the partial unwrapping thereof from about said rotatable members as they traverse said guideways from the convergent ends to the divergent ends thereof.

2. A device as described in claim 1, further including:

a scanning transducer; and

means for mounting said scanning transducer for movement by at least one of said rotatable members.

3. A device as described in claim 2, wherein said scanning transducer is attached to one of the rotatable members of said rolamite for movement therewith.

4. A roller band mechanism comprising:

a housing having at least two opposed walls;

a plurality of rotatable members disposed intermediate said walls and having combined cross-sectional dimensions greater than the maximum spacing be tween said walls;

a flexible band looped in a general S-shaped fashion about adjacent ones of said rotatable members; said band having a portion thereof secured to said housing and disposed adjacent one of said walls and having another portion thereof disposed adjacent the wall opposite; means for mounting at least one of said walls for alternate convergent and divergent movement with respect to the other said wall; means for applying a motive force to said movable wall to cause said wall to alternately converge and diverge with respect to the other wall; and extensible resilient support and band tensioning means, affixed to the end of said band which is oppositethe end of said band secured to said housing, for elongating to allow for increased wrapping of said band about said rotatable members due to said convergence of said guideways caused by said motive force and for taking up slack in said flexible band created by the partial unwrapping of said band from about said rotatable members during the movement of said members along said walls and for moving said rotatable members longitudinally between said walls whenever one of said walls is moved into convergence with its opposite wall at the ends of said walls at which said rotatable members then reside.

5. A data scanner, comprising:

a housing having at least two opposed walls;

a plurality of rotatable members disposed intermediate said walls and having combined cross-sectional dimensions greater than the maximum spacing between said walls;

a flexible band looped in a general S-shaped fashion about adjacent ones of said rotatable members; said band having a portion thereon secured to said housing and disposed adjacent one of said walls and having another portion thereof disposed adjacent the wall opposite;

means for mounting at least one of said walls for convergent and divergent movement with respect to the other said wall;

force applying and releasing means for causing said movable wall to alternately converge and diverge with respect to its opposite wall;

a data sensor associated with at least one of said rotatable members for longitudinal movement therewith; and

resilient support and band tensioning means affixed to the end of said band which is opposite the end of said band decured to said housing, said means being for elongating to allow for increased wrapping of said band about said rotatable members due to said convergence of said walls caused by said force applying and releasing means and for taking up slack in said flexible band created by the partial unwrapping of said band from about said rotatable members during the movement of said members along said walls and for moving said rotatable members longitudinally between said walls whenever one of said walls is moved into convergence with its opposite wall by said force applying and releasing means.

6. A data scanner as described in claim 5, wherein:

at least one of said rotatable members has a mounting member affixed to a face thereof for rotation with said rotatable member; and

said sensor is mounted on said mounting member for rotation therewith.

7. A data scanner, comprising:

a housing having at least two opposed walls;

resilient support and band tensioning means affixed to the end of said band which is opposite the end of said band secured to said housing, said means being for elongating to allow for increased wrapping of said band about said rotatable members due to said convergence of said walls caused by said force applying and releasing means and for taking up slack in said flexible band created by the partial unwrapping of said band from about said rotatable members during the movement of said members along said walls and for moving said rotatable members longitudinally between said walls whenever one of said walls is moved into convergence with its opposite wall by said force applying and releasing means;

a guide member supporting said sensor and for restraining rotation of said sensor with said rotatable member; and

one of said rotatable members is provided with a central axial aperture and said sensor is mounted on a member inserted into said aperture.

8. A data scanner as described in claim 7, wherein:

at least one of said rotatable members is provided with enlarged diameter end face flanges for guiding said rotatable member along a guideway and for keeping said other rotatable member in longitudinal alignment with said first rotatable member.

Claims

1. In a rolamite device having a plurality of rotatable members, a tension band looped about said members, and guideways confining said rotatable members and tension band, the improvement creating a reciprocating drive mechanism therefrom comprising, in combination: means for mounting at least one of the guideways for convergent and divergent movement with respect to the other guideway in response to a motive force; means for applying a motive force to said movable guideway to cause it to alternately converge and diverge with respect to the other guideway; and extensible resilient support and tensioning means affixed to one end of said band for resiliently holding said band in tension and to take up the slack produced in said band due to the partial unwrapping thereof from about said rotatable members as they traverse said guideways from the convergent ends to the divergent ends thereof.

2. A device as described in claim 1, further including: a scanning transducer; and means for mounting said scanning transducer for movement by at least one of said rotatable members.

4. A roller band mechanism comprising: a housing having at least two opposed walls; a plurality of rotatable members disposed intermediate said walls and having combined cross-sectional dimensions greater than the maximum spacing between said walls; a flexible band looped in a general S-shaPed fashion about adjacent ones of said rotatable members; said band having a portion thereof secured to said housing and disposed adjacent one of said walls and having another portion thereof disposed adjacent the wall opposite; means for mounting at least one of said walls for alternate convergent and divergent movement with respect to the other said wall; means for applying a motive force to said movable wall to cause said wall to alternately converge and diverge with respect to the other wall; and extensible resilient support and band tensioning means, affixed to the end of said band which is opposite the end of said band secured to said housing, for elongating to allow for increased wrapping of said band about said rotatable members due to said convergence of said guideways caused by said motive force and for taking up slack in said flexible band created by the partial unwrapping of said band from about said rotatable members during the movement of said members along said walls and for moving said rotatable members longitudinally between said walls whenever one of said walls is moved into convergence with its opposite wall at the ends of said walls at which said rotatable members then reside.

5. A data scanner, comprising: a housing having at least two opposed walls; a plurality of rotatable members disposed intermediate said walls and having combined cross-sectional dimensions greater than the maximum spacing between said walls; a flexible band looped in a general S-shaped fashion about adjacent ones of said rotatable members; said band having a portion thereon secured to said housing and disposed adjacent one of said walls and having another portion thereof disposed adjacent the wall opposite; means for mounting at least one of said walls for convergent and divergent movement with respect to the other said wall; force applying and releasing means for causing said movable wall to alternately converge and diverge with respect to its opposite wall; a data sensor associated with at least one of said rotatable members for longitudinal movement therewith; and resilient support and band tensioning means affixed to the end of said band which is opposite the end of said band decured to said housing, said means being for elongating to allow for increased wrapping of said band about said rotatable members due to said convergence of said walls caused by said force applying and releasing means and for taking up slack in said flexible band created by the partial unwrapping of said band from about said rotatable members during the movement of said members along said walls and for moving said rotatable members longitudinally between said walls whenever one of said walls is moved into convergence with its opposite wall by said force applying and releasing means.

6. A data scanner as described in claim 5, wherein: at least one of said rotatable members has a mounting member affixed to a face thereof for rotation with said rotatable member; and said sensor is mounted on said mounting member for rotation therewith.

7. A data scanner, comprising: a housing having at least two opposed walls; a plurality of rotatable members disposed intermediate said walls and having combined cross-sectional dimensions greater than the maximum spacing between said walls; a flexible band looped in a general S-shaped fashion about adjacent ones of said rotatable members; said band having a portion thereon secured to said housing and disposed adjacent one of said walls and having another portion thereof disposed adjacent the wall opposite; means for mounting at least one of said walls for convergent and divergent movement with respect to the other said wall; force applying and releasing means for causing said movable wall to alternately converge and diverge with respect to its opposite wall; a data sensor associated with at least one of said rotatable members for longitudinal movement therewitH; and resilient support and band tensioning means affixed to the end of said band which is opposite the end of said band secured to said housing, said means being for elongating to allow for increased wrapping of said band about said rotatable members due to said convergence of said walls caused by said force applying and releasing means and for taking up slack in said flexible band created by the partial unwrapping of said band from about said rotatable members during the movement of said members along said walls and for moving said rotatable members longitudinally between said walls whenever one of said walls is moved into convergence with its opposite wall by said force applying and releasing means; a guide member supporting said sensor and for restraining rotation of said sensor with said rotatable member; and one of said rotatable members is provided with a central axial aperture and said sensor is mounted on a member inserted into said aperture.

8. A data scanner as described in claim 7, wherein: at least one of said rotatable members is provided with enlarged diameter end face flanges for guiding said rotatable member along a guideway and for keeping said other rotatable member in longitudinal alignment with said first rotatable member.