US3432083A - Pinch roller - Google Patents

Description

March 11, 1969 J, RENTSCHLER ET AL 3,432,083

PINCH ROLLER Filed May 26, 1966 FIE 1 4 I V /1///l/ FIE 2 e, y WZQA, u, 5

mi M Em 0 7 m; 7 ed 4 Wm m/ f X m f United States Patent 3,432,083 PINCH ROLLER John H. Rentschler and Loren J. Sewall, Minneapolis,

Minn., assignors to Minnesota Rubber Company, Minneapolis, Minn., a corporation of Minnesota Filed May 26, 1966, Ser. No. 553,118 US. Cl. 226-186 7 Claims Int. Cl. B65h 17/20 ABSTRACT OF THE DISCLOSURE This invention relates to tape'driving assemblies. More particularly, it relates to tape-driving assemblies wherein a new and improved pinch roller construction is utilized to provide improved sound transducing performance.

Tape-driving assemblies, as they are known today, include serious disadvantages which are identified in the trade as wow and flutter characteristics. Such Wow and flutter characteristics are actually interferences which are transferred into the sound transducing equipment with the result that the performance is not as satisfactory as desired although, of course, in general the reproduction is considered to be of a high quality. In other words, al though it is possible to obtain a high quality performance in sound transducing equipment, there is still definite room for improvement particularly if wow and flutter characteristics can be completely eliminated or minimized. It is a general object of our invention to eliminate or substantially minimize the adverse effect of such wow and flutter characteristics and to thereby improve the general over-all performance of sound transducing equipment. We have accomplished this goal by providing a substantially improved tape-driving assembly.

The tape-driving assembly in sound transducing equipment is of primary importance for the wow and flutter characteristics are produced as a result of variations in the speed with which the tape is moved past the head, creating the wow characteristic and other interferences which are induced in a transverse direction to produce the flutter characteristic. We have found that we can substantially improve the performance of sound transducing equipment by improving the construction of the tape-driving assembly as outlined below.

It is a general object of our invention to substantially improve the performance of sound transducing equipment by eliminating or substantially minimizing the wow and flutter characteristics by providing a tape-driving assembly of improved and novel construction.

A more specific object is to provide a new and improved tape-driving assembly which will provide substantially 20-30 percent reduction in wow and flutter characteristics.

Another object is to provide a novel and improved tape- 3,432,083 Patented Mar. 11, 1969 ICC driving assembly construction which will greatly improve the quality of the second transduced by sound transducing equipment if the pinch roller is maintained at the same size and which will, if miniaturization is desired, provide the same level of performance with a tape-driving assembly of substantially lesser size.

Another object is to provide a tape-driving assembly having a pinch roller of such construction as to substantially eliminate and at least greatly minimize many of the adverse effects and consequences resulting from pinch roller constructions as heretofore known and utilized in sound transducing equipment.

Another object is to provide novel and improved tapedriving assemblies which will prolong the life of a tape so that satisfactory performance may be obtained from the sound transducing equipment for a greater period of time.

Another object is to provide novel and improved tapedriving assemblies which are particularly suited for use in slow moving tapes such as are utilized in automobile tapeplayers and are heretofore characterized, because of such slow movement, by the accentuation of the wow and flutter characteristics of the tape-driving assembly.

These and other objects and advantages of our invention will more fully appear from the following description, made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

FIG. 1 is a plan view of a transparent cartridge having a conventional tape therein and having the pinch roller thereof mounted in position so as to engage a conventional drive roll of a tape player;

FIG. 2 is a fragmentary sectional view taken approximately on line 22 of FIG. 1, with the drive roll shown in elevation; and

FIG. 3 is an end elevational view of the improved pinch roller shown in FIGS. 1 and 2.

The pinch roller of a tape-driving assembly is that portion of the assembly which pinches the tape against the drive roll so as to cooperatively move the tape past the sound transducing head. Pinch rollers, as heretofore known, are characterized by a metal or plastic hub which is mounted upon a fixed shaft and carries a suitable rubber tire or covering which may or may not be molded around the exterior of the hub and functions to engage the tape and press the same against the relatively hard drive roll of the tape-driving assembly. We have discovered that by utilizing a particular type of elastomer and by manufacturing the pinch roller entirely of such an elastomer and mounting the same directly upon the shaft rather than to utilize a hub, we can accomplish a 2030 percent reduction in wow and flutter characteristics in such a tape-driving assembly. It must be borne in mind that a pinch roller must be of such a construction that it will maintain its shape and press the tape against the drive roll in such a manner as to provide a uniform speed for the tape and at the same time minimize the transmission thereto of the high and low frequency interferences which are commonly referred to as Wow and flutter characteristics. We have found that if we eliminate the use of a metal or plastic hub entirely and mount the pinch roller directly upon the supporting shaft, we can accomplish a substantial reduction in such wow and flutter characteristics. Moreover, by manufacturing the pinch roller in such a manner as to minimize the contact between the end of the roller with the shaft supporting structure, we can substantially minimize the amount of interfering vibrations which may be transmitted to the tape to produce either the Wow or the flutter characteristics. We have found that we can substantially in crease the life-span of a tape while at the same time substantially improve the quality of performance.

To accomplish the above we have utilized an elastomer having a durometer of 5590 hardness Shore A and having high modulus characteristics. In addition, We eliminate the hub and manufacture the pinch roller entirely of this elastomer, the elastomer preferably being a urethane elastomer. As a result, we find that we are able to greatly diminish the production and transmission of vibration to the tape and consequently we are successful in substantially improving the quality of performance of the sound transducing equipment.

FIGS. 13 disclose the preferred embodiment of our invention wherein a sound transducing head 5 which is carried by a frame '6 is shown in tape playing position relative to a tape 7 disposed within a transparent plastic cartridge 8. It will be noted that the tape 7 is withdrawn from the innermost convolution of the coil of tape from whence it passes around an idler roll 9, past the head 5 and between the drive roll and the pinch roller, the latter being indicated generally by the numeral 11. The tape then passes to and becomes the outermost convolution of the coil carried by the reel 12. This arrangement is conventional in many tape-players. It will be noted that the cartridge 8 is adapted to he slid into the frame 6 to the position shown so that the drive roll 10 will extend into a recess 13 formed in the corner of the cartridge 8 to accommodate the same and permit the same to positively engage the tape and, with the pinch roller 11, cooperatively drive the same.

The construction of our pinch roller 11 is best shown in FIG. 2. The drive roll is driven by a source of power such as a motor (not shown) through a shaft 14 extending thereto. As shown, the drive roll is rotatably mounted on the frame 6 for rotation about a fixed axis. The cartridge 8 is formed in two opposing halves the lower which carries a hollow plastic post 15 and the upper which carries a snugly fitting shaft 16 which telescopes into the post 15 to cooperatively provide a fixed shaft upon which the pressure roller 11 may be mounted and about which it may rotate freely.

The pressure roller 11, as shown, is generally cylindrical in shape and has a central bore 17 within which a plurality of circumferentially spaced axially extending recesses 18 are formed. These recesses are for the purpose of retaining lubricant, such as a silicone grease, and the diameter of the bore is equal or only very slightly greater than the diameter of the shaft 15. The entire roller 11 is manufactured of an elastomeric material having a 55-90 durometer hardness Shore A and having high modulus characteristics. We prefer to utilize elastomeric material having a 60-80 durometer hardness Shore A with high modulus characteristics but we have found that we may utilize materials of 7090 durometer hardness Shore A without such materials being necessarily of the high modulus characteristics. It will be appreciated that the term high modulus characteristics, as is conventional in the trade, is utilized with reference to such characteristics with respect to a given durometer hardness Shore A.

Although we prefer to utilize a urethane elastomer, we find that silicone rubber, styrene butadiene rubber, ethylene propylene rubber, and nitrile butadiene may be utilized with satisfactory results.

As best shown in FIG. 2, we prefer to utilize a cylindrical shaped roller 11, the end portions of which are reduced as shown and indicated by the numerals 19 and 20. As shown in FIGS. 2 and 3, we have provided at each end of the roller an annular rib such as indicated by the numerals 21 and 24- which function as bearing surfaces against the side walls of the cartridge 8. By so reducing the contact between the roller and the walls of the cartridge 8, we find that We can greatly diminish vibrations and Scratching, etc., which are normally produced through contact and relative movements of the relatively hard materials present when a metal or plastic hub is utilized. Moreover, with the much greater mass of rubber utilized (for a given construction) any vibrations and other interferences are greatly dampened so that the interferences which are transmitted to the tape 7 that is pinched between the drive roll 10 and the pinch roller 11 are either eliminated or greatly diminished. Thus we have found that a tape-driving assembly of the type described herein will greatly improve the quality of performance of sound transducing equipment within which such an assembly is utilized. It will be appreciated, of course, that the radius of the roller 11 is equal to or slightly less than the distance between the tape engaging surface of the drive roll 10 and the axis of the shaft 16 in order to apply sufiicient pressure to the tape 7 to cause the latter to be positively driven by the drive roll 10 at a uniform speed.

It will be noted that the non-reduced portions of the roll 11 which define the tape engaging surface 22 have end surfaces which carry a plurality of concentrically arranged annular ribs 23 which extend axially away from such ends and define annular grooves or dams therebetween. The function of these ribs is to provide dams to prevent radial egress of the lubricant to the tape engaging surface 22 with consequent destruction of the tape.

As indicated above, we have found that a tape-driving assembly of the type disclosed herein appears to prolong the life of the tape if the same size pinch roller is utilized since it does not wear off the lubricant from the back side of the tape as readily as a conventional pinch roller. Removal of the lubricant from the back side of the tape tends to cause the tape to pull off the reel with more difficulty and consequently induce wear upon the front side of the tape with the net result that the tape will have a shorter life span. We have found that we obtain a better performance from sound transducing equipment if our pinch roller construction is utilized and we believe that this can be attributed to the substantial reduction of surface contact between the ends of the roller and the case or mounting, to the provision of a greater mass of dampening material, and to the elimination of relative movement between relatively hard materials which cause scratching and other vibrations that are readily transmitted to the tape and cause the tape to progress irregularly with consequent wow and flutter characteristics. Moreover, we have found that because of this improved performance it is possible to miniaturize pinch rollers substantially and still obtain the level of performance currently available or, in the alternative, we can produce the pinch roller of the size presently being utilized and greatly improve the quality of sound transduced.

It will be understood, of course, that our improved pinch roller may be utilized in tape players other than those which employ cartridge tapes.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of our invention which consists of the matter shown and described herein and set forth in the appended claims.

What is claimed is:

1. A tape-driving assembly for cooperatively moving a tape past a sound-transducing member comprising:

(a) a drive roll mounted for rotation about its axis and having a tape-engaging circumferential surface;

(b) a nonrotatable shaft positioned adjacent said drive roll and having a longitudinal axis extending parallel to said axis of said drive roll;

(c) an all-elastomeric generally cylindrically shaped member having a -9O durometer hardness Shore A and high modulus characteristics and a cylindrical uninterrupted tape-engaging surface defining the maximum radial dimensions of said member;

((1) said member having an axially extending bore and axially outwardly extending protuberances carried by at least one end of said member, said member being mounted directly on said shaft in shaft-engaging pierced relation for rotation thereabout; and

(e) the radius of said cylindrical tape-engaging surface being equal throughout its axial length to the distance between said longitudinal axis of said shaft and said tape-engaging surface of said drive roll to adapt the same to engage and resiliently hold such a tape against said drive roll surface in driven relation thereto.

2. A tape-driving assembly for cooperatively moving a tape past a sound-transducing member comprising:

(a) a drive roll mounted for rotation about its axis and having a tape-engaging circumferential surface;

(b) a nonrotatable shaft positioned adjacent said drive roll and having a longitudinal axis extending parallel to said axis of said drive roll;

(c) an all-elastomeric generally cylindrically shaped member having a 55-90 durometer hardness Shore A and high modulus characteristics and a cylindrical uninterrupted tape-engaging surface defining the maximum radial dimensions of said member;

(d) said member having an axially extending bore and being mounted directly on said shaft in shaft-engaging pierced relation for rotation thereabout, said member further including radially reduced end portions and a nonreduced tape-engaging intermediate portion, and annularly arranged bearing structure carried by at least one of said reduced end portions and extending axially outwardly therefrom and formed integrally therewith to provide minimal bearing area for the rotation of said member when its axis of ro tation has a vertical component; and

(e) the radius of said cylindrical tape-engaging surface being equal throughout its axial length to the distance between said longitudinal axis of said shaft and said tape-engaging surface of said drive roll to adapt the same to engage and resiliently hold such a tapeagainst said drive roll surface in driven relation thereto.

3. A tape-driving assembly for cooperatively moving a tape past a sound-transducing member comprising:

(a) a drive roll mounted for rotation about its axis and having a tape-engaging circumferential surface;

(b) a nonrotatable shaft positioned adjacent said drive roll and having a longitudinal axis extending parallel to said axis of said drive roll;

(c) an all-elastomeric generally cylindrically shaped member having a 5590 durometer hardness Shore A and high modulus characteristics and a cylindrical uninterrupted tape-engaging surface defining the maximum radial dimensions of said member;

((1) said member having an axially extending bore having at least one axially extending lubricant-retaining recess formed in its bore-defining surface, and being mounted directly on said shaft in shaft-engaging pierced relation for rotation thereabout; and

(e) the radius of said cylindrical tape-engaging surface being equal throughout its axial length to the distance between said longitudinal axis of said shaft and said tape-engaging surface of said drive roll to adapt the same to engage and resiliently hold such a tape against said drive roll surface in driven relation thereto.

4. A pinch roller assembly for pinching a tape against a capstan comprising:

(a) a fixed nonrotatable rigid shaft;

(b) an all-elastomeric generally cylindrically shaped member having a 55-90 durometer hardness Shore A and high modulus characteristics, said member including integrally formed protuberance structure with minimal contact area arranged concentrically of the bore of said member and extending axially outwardly therebeyond from at least one end of said member to function as a bearing for said member when the axis of said shaft has a vertical component; and

(c) said cylinder having an uninterrupted cylindrical tape-engaging surface defining the maximum radial dimensions of said cylinder and an axially extending bore and being mounted directly on said shaft in shaft-engaging relation for rotation thereabout.

5. A tape-driving assembly for cooperatively moving a tape past a sound-transducing member comprising:

(a) a drive roll mounted for rotation about its axis and having a tape-engaging circumferential surface;

(b) an all-elastomeric generally cylindrically shaped member having a 5590 durometer hardness Shore A and high modulus characteristics, said member including at least one annular rib formed on at least one of its ends and extending axially outwardly therefrom to arrest flow of lubricant from the bore of said member to its tape-engaging surface; and

(c) said cylinder having an uninterrupted cylindrical tape-engaging surface defining the maximum radial dimensions of said cylinder and an axially extending bore and being mounted directly on said shaft in shaft-engaging relation for rotation thereabout.

6. A tape-driving assembly for cooperatively moving a tape past a sound-transducing member comprising:

(a) a drive roll mounted for rotation about its axis and having a tape-engaging exterior surface;

(b) an all-elastomeric cylindrically shaped member having a uniform hardness throughout of 55-90 durometer Shore A and an uninterrupted cylindrical tape-engaging surface, said member including an axially extending shaft-engaging surface defining a central bore and having at least one axially extending lubricant-retaining recess formed therein and extending throughout the axial length of said shaft-engaging surface;

(c) and a nonrotatable shaft having a longitudinal axis extending parallel to said axis of said drive roll and disposed to support said elastomeric member in tapeengaging relation with said drive roll and being fixed with respect to said drive roll when said elastomeric member is so disposed, said tape-engaging surface of said elastomeric member, when the latter is so disposed, engaging such tape and resiliently holding such tape against said drive roll surface in driving relation thereto.

7. In a tape-driving assembly having a main housing including a sound transducing member and a drive roll mounted for rotation about its axis including a tape-em gaging circumferential sunface and having a tape cartridge adapted to be inserted into the main housing in operable engagement with the drive roll and the sound transducing member, the improvement comprising:

(a) an all-elastomeric cylindrically shaped member having a uniform hardness throughout of 55-90 durometer Shore A and an uninterrupted cylindrical tape-engaging surface, said member including an axially extending shaft-engaging surface defining a central bore and having at least one axially extending lubricant-retaining recess formed therein and extending throughout the axial length of said shaftengaging surface; and

(b) a nonrotatable shaft having a longitudinal axis extending parallel to the axis of the drive roll and fixedly disposed within the tape cartridge and adjacent the periphery thereof to support said elastomeric member in tape-engaging relation with the drive roll in the main housing and being fixed with respect to the drive roll when the tape cartridge and elastomeric member are operably inserted in the main housing, said tape-engaging surface of said elastomeric member, engaging such tape and resiliently holding such tape against said drive r011 surface in driving relation thereto.

References Cited UNITED STATES PATENTS 2,959,334 11/1960 -Uritis 226191 3,042,281 6/1962 B alvin et a1. 226l91 3,073,590 1/1963 Romeo et a1. 226-187 8 3,132,788 5/1964 Johnson 226-186 3,310,214 3/1967 Nesin 226181 2,990,092 6/1961 Begun et a1. 226-491 X M. HENSON WOOD, 111., Primary Examiner.

RICHARD A. SCHACHER, Assistant Examiner.

US. Cl. X.R. 226-190

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