FR2489575A1 - BAND ELEMENT DRIVE DEVICE - Google Patents

Abstract

TAPE DRIVE DEVICE. IT INCLUDES TWO BLOCKS 30, 40 OF WRAPPED TAPE CARRIED BY ROTATING HUBS 29, 39 AND COUPLED TOGETHER BY A SOFT ENDLESS BELT 23 WHICH IS IN FRICTIONAL SUPPORT WITHOUT SLIP AGAINST THE OUTER LAYERS OF THE BLOCKS AND PASSES IN A BELT TENSIONER WHICH INCLUDES AT LEAST ONE HARD ROLLER 20, 22 AND ONE ROLLER 21 WITH VISCO-ELASTIC SURFACE 48 PRESSES AGAINST ANOTHER ON THE OPPOSITE SIDES OF THE BELT AND THUS GENERATES A ROLLING FRICTION SO THAT, WHEN THE BELT IS PULLED BETWEEN THE ROLLERS, THE PART OF THE BELT LEAVING THE TENSIONER IS TENERED THAN THAT ENTERING IT, BELT 23 THUS NOWING THE BAND UNDER THE DESIRED TENSION BETWEEN THE BLOCKS. APPLICATION TO MAGNETIC TAPE CASSETTES FOR HIGH QUALITY DIGITAL, ANALOGUE OR AUDIO RECORDINGS.

Description

The present invention relates to the devices

  bands and it relates to

  more particularly to training devices

  element in bands that consist of two blocks of ele-

  in strips coupled by a belt for winding

  and unroll the strip element from one block to the other.

  A band-type driving device with accu-

  strap used in a tape cartridge

  magnetic is particularly interesting.

  The basic principle of the operation of magnetic tape drives, in

  cassettes or not, which use belt belts

  endless, thin and flexible, to carry the

  tape from one coil to another energized is the

  flat belt with two pulleys. In such a belt drive, one pulley is the "driving" pulley and the other is the "driven" pulley or the "load". In such a device, there is a soft strand (under a low tension) and a stretched strand (under a high tension) of the endless belt, the tensioned strand being always "downstream" of the driven pulley, in the direction of moving the belt, and being located between the driving pulley and the driven pulley. Since any elastic material elongates when it is under tension, the stretched strand of the endless belt is more

  thin than the soft strand and, since such arrangements

  belt drive systems are always endless closed-loop systems, the continuity of the mass flow must exist to meet the laws

  of physics. This means that at any point in the

  belt drive, an equal amount of belt mass must pass per unit of time. This therefore requires that the speed of the belt in the strand

  stretched (thinner) of a training device to

  must be larger than the speed of the belt

  in the soft strand (larger) in a proportionate

  the difference in thickness.

  Magnetic tape cassettes have already been manufactured in various configurations and in a variety of ways.

  range of capabilities for recording applications.

  sound, analogue and digital The first models

  the tape cassettes used capstans with pressure rollers to move the web and various slide coupling or brake configurations as part of the coiled drive devices to create web tension. Since the application of the Coulomb friction law in any mechanical device results in high energy losses and poor control capacity, the first cassettes left much to be desired in terms of accuracy and reliability. uniformity of speed for applications to the recording of

  analog data. In addition, because of energy losses,

  it was not possible to obtain rapid acceleration and deceleration for applications to

digital computers.

  Magnetic tape units are already known

  and belt-driven magnetic tape cassettes in which an endless flexible peripheral belt is in contact with a coil-wound tape block (a tape wound on a rotatably mounted bobbin hub) in such a manner that Belt movement produced by external sources of rotational energy causes the conveyance of the tape from one block of tape to another. Such devices are described in the following documents: IEE Transactions on Magnetics, Vol. MAG-14 No. 4, July 1978, pages 171-175, Newell article entitled "An Improved ANSI-Compatible Magnetic Tape Cartridge", US Patent Nos. 2,658,398, 2,743,878; No. 3,114,512; No. 3,125,311; No. 3,154,308, No. 3,297,268; No. 3,305,186; No. 3,467,338; 3,514,049, 3,620,473; Nos. 3,692,255 and 3,907,230 and patents

  French 2,212,981; Nos. 2,220,841 and 2,260,165.

  In magnetic tape units and tape-driven magnetic tape cassettes, the

  belt is preferably separated from the magnetic tape

  tick while the tape passes the magnetic heads.

  Recording and reading ticks to minimize disruption of web movement due to elasticity differences between belt and web. We create the tension in the magnetic strip in

  causing the belt to move to the hoisting side

  or receiver, of the training device at a speed slightly greater than that at which it

  moved on the unwinding side, or debtor, as described above.

  above. This result is achieved by using double differential capstans or braking devices in

the path of the belt.

  Belt-driven cassettes

  described in the prior art possesses

  effectively tooth the ability to produce a live motion of the web in both directions and can be removed en bloc from the tape unit as stand-alone devices. However, because of the very low modulus of elasticity of the elastomeric belts used in some cassettes, which is necessary to power up the tape, the resonant frequencies of the belt systems are so low that they greatly limit the rates.

  acceleration and deceleration or departure times-

  stopping tape drive devices in casset-

  you. High acceleration and deceleration rates are of vital importance for high speed computer tape units. A quick acceleration

  of the tape in the cassettes of the prior art technique.

  re can also produce tension stresses

  excessive and harmful in the substrate of the strip.

  In addition, the elastic characteristics of the belts do not allow the precise control of the variations of

  instantaneous speed which is essential for recording

  high-frequency precision analogue and for high-speed digital recording and

  high flux inversion density used in

cations to computers.

  The prior art teaches, in general, the construction of belt cassettes driven by a peripheral belt which requires the use of elastomeric material belts having

  very low elastic moduli and prior art.

  However, there is no means for accurately adjusting the useful tension of the web after completion of the cassette assembly. In the cassettes of the prior art, the useful tension of the strip is

  invariable after assembly of the device and is

  the physical and elastic characteristics of the materials used and the variations in the dimensions of the

  parts of the cassette, due to manufacturing tolerances

  cation. Thus, the main means used in the prior art to create the voltage difference in the endless belt have been mechanical braking devices, differential double capstans, coulomb friction or clamping a thick

  rubber strap. A disadvantage of these provisions

  of the prior art, apart from the one

  uses braking means, is that it is not possible

  to adjust the useful tension of the belt after assembly.

  elements. The final tension is determined by the manufacturing tolerances of the individual parts and by

  the elastic characteristics of the material of the cour-

  and variations in these characteristics. The disadvantages of the prior art devices which use mechanical braking means are, in particular, their low reliability and the nonuniformity of the voltage due to uncontrollable variation and often

  instantaneous friction characteristics of the materials

  used and the significant variation in the characteristics of

  friction coefficient as a function of temperature and

employment.

  Briefly, an embodiment of the

  The present invention is a device for driving a strip element. Two rotating band element blocks wind up and unwind between them the strip element. An endless belt couples rotationally between the web-like block members, without slippage between the belt and the web member, and a belt tensioner creates a greater tension in the portion of the endless belt that leaves the belt. Belt tensioner only in the one that enters it. The belt tensioner comprises at least first and second rotary rollers. The first pebble has a periphery

  hard surface and the second roller has an outer periphery

  visco-elastic. The first and second rollers are pressed against each other on opposite sides of the endless belt so that when the belt is pulled between them, the rolling friction between the rollers creates a higher tension in the part. of the

belt that leaves the tensioner.

  With the embodiment of the present invention, it is now possible to achieve a mechanically reliable and simple tape tensioning mechanism which does not have the disadvantages and limitations of the

  devices of the prior art.

  With one embodiment of the present invention, it is also possible to provide means and a mechanism for accurately adjusting the final payload of the web after assembling the web member driving device, thereby enabling to compensate for the tolerances of the organs and the variations of the elastic characteristics of the endless belt and other material of the organs. An embodiment of the present invention also allows the use of endless belts having a high tensile modulus of elasticity. As a result, the training device can be used in

  tape cassettes used in

  cations for high-speed, high-density digital recording, such as those used in computers.

  In addition, the embodiment of the

  vention makes it possible to create a mechanism for

  magnetic tape intended for use in

  cases where it is necessary to make a registration

  highly accurate or low-wheeze analog with reliable performance over a wide range of

  temperatures and under severe ambient conditions.

  The embodiment of this

  The invention also has great flexibility in adapting

  to adapt it to specific needs

individual applications.

  Other features of the invention

  will appear on reading the following description

  and examining the accompanying drawings in which:

  Figure 1 is a Shematic representation

  that of the fundamental phenomenon of rolling friction; Figure 2 is a diagram that represents a

  type of tensioning mechanism used in one embodiment of

  of the present invention; Fig. 3 is a diagram showing a preferred tensioning mechanism for use in a preferred embodiment of the present invention; Fig. 4 is a diagram showing another preferred tensioning mechanism for use in another preferred embodiment of the present invention; Figure 5 is a schematic plan view

  a magnetic tape drive intended for

  to be used in applications for recording

  digital high speed under a high density, the boot having been removed to show the internal organs of the cassette; Figure 6 is a schematic plan view

  a tape cassette intended to be used

  in applications for analog recording and precision audio and embodying the present invention; the box was removed to show the internal organs of the cassette;

  Figure 7 is a schematic isometic view

  another cassette or a magnetic tape unit.

  which has coaxial coils for the recording of

  either numerically or audio, embodying the present invention;

  Figure 8 is an isometric diagrammatic view

  another cassette or other unit

  magnetic stripe with coaxial coils for

  analog precision record, embodying the present invention; Figure 9 is an enlarged top plan view of the tensioning mechanism shown in Figure 5, this view showing the mechanism which serves to fine-tune the useful tension of the web;

  Figure 10 is a sectional view of the mechanism

  tensioning device of Figure 9, along the lines 10-10 of Figure 9; and Figure It is a view from below of

  tape tensioner mechanism, seen through the boot.

  Figure 1, to which reference will be made, represents a hard cylinder rolling on a flat surface of elastomeric material. Based on in-depth scientific studies and on experimental as well as analytical analysis, the principles of what is called in the

  technical "rolling friction" are mathematical-

  well defined and empirically verified. Scientific studies have shown that the energy losses that occur when rolling a hard cylinder under a

  load on a surface of elastomeric material are mainly

  because of elastic hysteresis losses in the

  elastomeric material. The magnitude of the rolling friction

  depends on the load or the amount of deformation of the elastomeric material, the diameter of the hard

  elastic characteristics of the elastomer.

  It has been shown that when a hard roll rolls on a flat elastomeric surface, the elastomer in the forward portion of the contact circle segment is compressed so that elastic work is performed on it. The elastomer which is in the back part of the contact circle resumes elastically

  its shape and pushes the cylinder forward. If the elasto-

  mother was ideally elastic, the energy

  due when the elastomer resumes its shape would be exactly

  This is equal to the energy expended for compression in the forward portion of the contact region so that no net force would be required to rotate the cylinder. In practice, however, all

  elastomers behave like viscoelastic

  and dissipate energy, when deformed, by internal friction or hysteresis. It's this loss

  of energy during the recovery of shape of the elastic material

  tomère which is reflected in the work necessary to roll the cylinder on the surface. If we consider a cylinder 1 having a radius R, subjected to a load W per unit length of the cylinder and if we denote by 2a

  the rope of the contact arc with a substrate 2 in

  In the elastomer, the pressure at a point X of the contact center is given, according to the old Hertz (1881) analysis, by the equation A. If the cylinder moves forward on a very small distance J, the work done by the pressure on a band of width dx will be pdx (xJ / R) and the total work done by the front half of the cylinder

will be given by equation AA.

  Therefore, the work done per unit of displacement distance of the cylinder is given by equation B. A complementary analysis carried out by Hertz shows that the equation BB applies, equation in which -E is the modulus of elasticity of Young ety is

the ratio of Poisson.

  By substituting for this value the term "a" in the equation that defines the work performed per unit length of the cylinder, equation C is obtained. Figure 2 shows a tensioning mechanism

  tape intended for use in the present invention.

  who uses the phenomenon to

  conducts rolling friction in a winding mechanism

  their tape or tape element, such as a recording

  two-coil belt-type or tape cassette. This diagram shows a cylinder or hard roller 3 which is rotatably mounted, ideally by means of a bearing without friction, on an axis 4. The roller 3 mounted on the shaft is pushed into contact with a second roller by the reference 6 on the outer periphery of which is bonded a thick bandage 5 of elastomeric material and which also mounted to

  rotation, ideally by means of a friction-free

  on a fixed axis 7. The hard cylinder 3 is firmly

  pressed into the tire 5 made of elastomeric material for

  a certain deformation value of the elastomer and a thin endless flexible belt 8 is placed between the two rollers and subjected to a prior tension by application of a pulling force T2 *.

  that the T1 pulling force required to make

  The two cylinders 3 and 6 in the direction indicated by the arrows and to move the belt in the direction indicated by the arrow 18 is greater than the force T2 by an amount proportional to the amount of deformation of the tire 5. elastomeric material. The axis 4 is movable or adjustable so that the pressure between the rolls 3 and 6 can be selected and adjusted to produce the required voltage value. The way in which the axis 4 and, consequently, the cylinder 3 are

  set will be described with reference to Figures 9-11.

  We can calculate the magnitude of the force T1 so

  using the equation C. This method of

  it works in both directions; however, the diameters of the rolls 3 and 6, designated respectively by the reference R1 and by the reference R2, must be equal so that the force T2 has, after reversal of the direction of movement, the magnitude that the force T1 had before

the inversion.

  Figure 3 represents a tense mechanism

  preferred bandwidth for use in the

  present invention. With this arrangement, a central roller

  tral 10 on which is bonded a thick tire 9 of elastomeric material is rotatably mounted, preferably by means of a bearing without friction, on a fixed axis 14. In this embodiment, two cylinders or hard rollers 11 and 12 likewise diameter, indicated by the radius R, are rotatably mounted, ideally by means of rolling without friction, on moving axes or it

  13 and 15 respectively (these axes are

  in the manner described with reference to axis 4 of the

  Figure 2). The cylinders 11 and 12 are arranged symmetrically

  around the central cylinder 10, as shown.

  Each of the hard rollers 11 and 12 is mounted so that it can be pressed individually in the tire 9 of elastomer material of the roller 10. A thin flexible endless belt 16 is placed between the two hard rollers 11 and 12 and the bandage 9 in matter

  elastomer of the central roller 10 and is subjected to

  beforehand by a pulling force T2. The pulling force T1 required to rotate the three rollers in the direction indicated and to move the belt in the direction of travel indicated by the arrow

  17 is greater than the force T2 of a proportional quantity

  the importance of the deformation of the elastomeric material 9 at the points of contact with the hard rollers 11 and 12. It is also possible, in this case, to calculate with accuracy, by means of the equation C, the magnitude of the force T1 needed to move the belt 16. The embodiment also works in both directions. The advantage of this embodiment over that shown in FIG. 2 is that the diameter R of the hard rollers 11 and 12 and the diameter R2 of the central roller 10 can be chosen in the manner described in FIG.

  optimal for the best performance.

  However, the diameters of the hard rollers 11 and 12 must be equal so that the force T2 has, after reversal of the direction of movement, a magnitude equal to that which had

the force T1 before this inversion.

  FIG. 4 shows another tensioning mechanism that can be used in accordance with the present invention, although its use is less advantageous than that shown in FIG. 3. According to this arrangement, a hard cylindrical roller 104 is disposed centrally and

  mounted, ideally by means of a frictionless bearing

  On a fixed axis 105, two cylindrical rollers 102 and 107 are mounted symmetrically around the central roller 104, as shown. Thick bandages 101 and 106 of elastomer material are glued respectively

  on the cylindrical roller 102 and on the cylindrical roller

  107. The outside diameters of the tires 101 and 106 of elastomeric material must be equal and each of the rollers 102 and 107 is rotatably mounted, ideally by frictionless rolling means, on a movable or adjustable axis 103 and, respectively, 108 ( adjustable in the manner described with reference to axis 4 of Figure 2). Each of the rollers 102 and 107 provided with a bandage of elastomeric material is mounted so that it can

  be pressed individually against the hard roller 104.

  In this embodiment too, a thin

  flexible endless belt 110 is placed between the hard roller 104 and the rollers 102 and 107 each provided with a bandage

  elastomer material and is subjected to a pre-tensioned

  In this embodiment also, the pulling force T1 required to rotate the three rollers in the indicated directions and to move the belt 110 in the direction indicated by the arrow 109 is superior. to the T2 force of a size proportional to the deformation

  bandages 101 and 106 at their respective contact points

  with the hard roller 104. The magnitude of the force T1 can also be accurately calculated using Equation C.

  This embodiment also functions

  in both directions; however, the fact that the belt is in contact with the elastomeric tires of the rollers 102 and 107 can produce undesirable instantaneous variations in the force of the

T1 traction.

  Figure 5 shows a tape cassette intended primarily for use in

  tape recorders in a digital data cassette

  high speed and high density used for computer applications, this cartridge embodying the present invention. In this embodiment a common base 19, which is the lower part of the casing of the cassette, ensures the assembly of all organs. A thin endless flexible belt 23 is guided through the tensioning mechanism, 21, 22, similar to that described with reference to FIG. 3, and is guided by pulleys 27 and 42 of belt return which, ideally, are mounted on the

  bearings without friction, and on a gabestan of

  34 which is also ideally mounted on bearings without friction so as to come into contact with the magnetic tape blocks 30 and 40 on

  an arc of at least 75. The belt has a trans-

  and a modulus of elasticity uniform throughout the length and is preferably coated with a thin layer of a high friction polymer to form a non-slip interface with the blocks

  wound tape 30 and 40 and with the training capstan

  34. The material of the belt preferably has

  a minimum modulus of elasticity of 280 hbar.

  The two idler belt pulleys 27 and 42 are mounted on pins 26 and 46 carried by respective brackets 25 and 43 which are pivotally mounted

  respectively about an axis 28 and about an axis 45.

  The supports 25 and 43 are pivotally mounted on the base 19 about the axes 28 and 45 in such a way that they can pivot the idle pulleys 27 and 42 when they are biased by compression springs 24 and 44 in directions that subject the belt to tension

prior.

  The forces exerted by the springs of

  24 and 44 on the supports 25 and 43 are

  to be of a size suitable for generating in the belt an initial tension which is large enough to prevent slippage between the belt 23, on the one hand, and the wrapped tape blocks 30 and 40 and the capstan drive 34, on the other hand, under the most unfavorable conditions of acceleration and inertia. This spring-mounted method of

  belt return pulleys 27 and 47 also compensates for

  the changes in the minimum belt length required when the web is transferred from one roll to the other without any loss of useful tension in the belt.

  Two coil hubs 29 and 39 on the

  which the magnetic tape is wound are mounted, ideally by means of frictionless bearings, on pins 31 and 41 which are rigidly fixed to the base 19. The band 33 is wound in a spiral on the coil hubs 29 and 39, in in opposite directions, so as to allow the transport of the web under tension from one reel hub to the other. A tape guiding path is defined by three web guides 32, 36 and 38 disposed between the two reel hubs so that the web

  is brought into contact with a set 37 of magnetic head

  read / write and prevented from entering into

  The drive capstan 34 is rotated clockwise with respect to the Figure by an external capstan motor 47, which causes the capstan to move. belt 23 following its guided course also in the direction of clockwise, as indicated by the arrows. This movement of the belt causes, thanks to the non-sliding contact of the belt with the outer strip thickness of the rolled tape blocks 30 and 40, the transport of the web, of the reel hub 39, which is the reel for this direction of movement of. the web, up to the spool hub 29, which

constitutes the receiver coil.

  The elastic deformation adjusted with precision

  of the elastomer tire 48 of the central roller 21 at its points of contact with the hard rollers 20 and 22, as described with reference to FIG. 3, requires that the part of the belt in contact with the belt on the block of the receiving belt 30 is further tensioned to pull the belt through the tensioning mechanism than the portion of the belt in contact with the belt on the debonding belt block 40. This increased tension of the portion of the belt on the receiving side has This causes the belt to move faster on that side than the portion of the belt on the debtor side to maintain the continuity of the mass flow. This increased speed of the belt on the receiving side causes tension of the web when the

  band is already stiff and it also gives the mechanis-

  me the ability to remove any slack that could occur in the band between the debtor and receiver band blocks when no slippage occurs between

the band and the belt.

  The roller control means shown in FIGS. 9 to 11 will now be described. This arrangement allows precise adjustment of the useful tension of the web in the cassette after the cassette has been fully assembled. The central roller 21 on which a thick tire 48 of elastomeric material is bonded is mounted by means of ball bearings 52, ideally without friction, on a fixed axis 51. The axis 51

  is rigidly fixed to the base 19. The cylindrical rollers

  20 and 22 are both mounted by means of ball bearings 50, ideally without friction, on

  axles 54 and 55 respectively mounted eccentrically

  is lying. The eccentric arrangement of the axes makes it possible to adjust with precision the elastic deformation of the tire 48 made of elastomeric material so as to obtain and maintain the exact value of the desired tension of the strip. The eccentric shafts are rotatably mounted on the base 19 by means of retaining rings 53 or similar mounting devices. After adjustment, the eccentric axes are immobilized in rotation relative to the base 19

by means of machine screws 56.

  We will now refer to the mode of

  This embodiment is a tape cassette primarily designed for use in analog and audio recording applications.

  precision with a low weep. In this embodiment,

  All of the members are also mounted on a common base 200. Three rollers, which have been designated by the general reference 204, are essentially identical to the rollers 20, 21 and 22 which constitute the tensioning mechanism of FIG. for pre-tensioning the belt are substantially the same as the elements 24 to 28 in FIG. 5 and the elements 208 for pre-tensioning the web are substantially the same as the elements 42 to 46 in FIG. . The

  main difference in this mode of

  5 is that a single external motor driven capstan 68 is in direct contact with the magnetic tape and thus constitutes the direct means for moving the tape 80,

  supply spool 77 to the take-up spool 62.

  In this embodiment, the belt 79 is a passive element and serves only to establish the tension of the belt. Instead of going around a drag capstan, as in the embodiment of the

  Figure 5, the belt 79 is guided around two

  64 and 75 of the belt remover which are mounted

  means of rolling ideally without friction,

  Actually on a fixed axis 66 and on a fixed axis 74. This guidance of the belt 79 ensures a minimum winding angle or contact of the belt 79

  with the wrapped tape blocks 61 and 76 considerable

  This increased contact angle with the rolled tape blocks requires only a much lower initial tension value of the belt by the tensioning members 206 and 208. in turn, a very regular rotational movement of all rotating bodies and serves as the basis for the low-wheezing performance necessary for precision analog recording and for the audio recording of very

high quality.

  The web 80 is guided between the debonded roll tape block 76 and the receiver rolled tape block 61 by at least three low friction web guides 65, 71, and 73. The single outer capstan 68 has

  engine is in direct contact with the magnetic

  tick 80 to ensure very fast speed control

  which is essential for the registration of

  with a faint wail. The sliding frictionless interface between the motor capstan 68 and the belt is achieved by a spring-loaded pressure roller 75 which firmly grips the belt against the capstan. As shown in FIG. 6, this is preferably effected by mounting the pressure roller 67 rotatably on an axis 81 which is rigidly fixed to a support 70. The support 70 is pivotally mounted by means of an axis 82 on a support 83 so that it can be pushed under pressure against the outer capstan 68 motor by a compression spring 69. A support 84 has a C-shaped and serves as a support for mounting the spring 69 and organ retainer for the support 70 for mounting the pressure roller when the pressure roller 67 does not bear against the capstan 68 with its motor. Access allowing contact between the

  magnetic tape and heads 72 for reading and recording

  between two Band Guides 71 and 73,

low friction.

Referring now to Figure 7 which shows a tape unit or a tape cassette in which the receivers and receivers coiled band blocks 202 and 204 are placed in one arrangement.

  coaxial. This embodiment is more particularly

  suitable for digital data recording applications. In this embodiment, an endless belt 90 is guided in a loop path

  closed so that it is in non-slip contact

  with the debonded wrapped tape block 212 between the idler pulleys 100 and 92 of the belt guide. Upon leaving the belt guide idler pulley 92, the belt passes between the elements 93, 94, 95 and 96 of the tensioner mechanism so that the belt 90 is in non-slip contact with the receiver rolled belt block 210 between the pulleys. Crazy 91 and 99 belt guide. The elements 93 and 96 are hard rollers similar to the rollers 20 and 22 of FIG. 5. The element 94 is a central roller and the element 95 is

  a tire of elastomeric material respectively similarly

  21 and the tire 48 of FIG. 5. Pressure is applied between the rollers 93 and 96 and the tire 95 made of elastomeric material as described with reference to FIG. 5. previously explained, the belt 90 moves faster in its part between

  the drive roller 98 and the roller 93 of the

  The tensioning mechanism, which is in non-slip contact with the debonded wrapped tape block 212, also provides a useful and accurately adjustable web tension in this embodiment. For the sake of clarity, the actual wound tape blocks 210 and 212 have been shown partially broken away in FIG. 7. The belt drive capstan 98 mounted in the cassette provides non-slip contact between the belt and a belt. external capstan 97 motor, in a manner similar to that described with reference

in Figure 5.

  Figure 8 represents yet another mode of

  embodiment of the invention in which the mechanism

  The tape drive is incorporated in a tape drive or

  tape cassette in which tape blocks

  The debtor and receiver 216 and 214 are placed in a coaxial arrangement. This embodiment is more

  particularly suitable for applications in the field of

  analog recording or recording

high quality audio.

  In this embodiment, an endless belt 11OA is guided in a closed loop path so that it is in non-slip contact with the debonded wrapper block 216 between idler pulleys 119 and 112 for belt guidance. Upon leaving the belt guide idler pulley 112, the belt 11A passes between the elements 113, 114, 115 and 116 of the tensioner mechanism so that the belt 90 is in non-slip contact with the receiver rolled belt block 214 between the

  idler pulleys 111 and 118 for belt guidance. accordance

  In accordance with the previously described principles, the belt, in this embodiment, moves at a greater speed between the idle pulleys 111 and 118 where the belt is in contact with the take-up reel than between the idle pulleys 112 and 119 where the belt is in contact with the supply reel. The elements-113, 114, 115 and 116 are identical to the elements 20, 21, 48 and 22 of Figure 5 and operate in the same way. In this way, a useful and adjustable band tension with

  precision is also generated in this embodiment of

  tion. For the sake of clarity, the actual wound-up tape blocks are shown partially broken away in FIG. 8. In this embodiment, the tape 122 which is wound in the debtor and receiver tape blocks 216 and 214 is driven directly by a capstan. 121 external motor cooperating with a

  pressure roller 120 spring to form an inter-

  sliding-free face, similar to that described with reference to FIG. 6. The portion of the strip 122 located between the debiting and receiving rolls

  and in contact with the power capstan has been

on the figure.

  During the description of the embodiments

  of the present invention and in the general description of

  In accordance with the principles of the invention, reference has been made to the use of belts having a modulus of elasticity of 280 or more hars. The use of belts having this modulus of elasticity constitutes the embodiment

  preferred because of the particular applications

  these embodiments. However, the principles of operation of the tensioning mechanism of the

  present invention are also applicable to

  Belt rests with lower elastic moduli

at 280 hbars.

  The operating principle of this tensioning mechanism

  is based on the energy losses that occur during

  a hard roller (roll) is rolled under a load on an elastomeric material that is softer than the

  hard pebble material. These energy losses are essential

  This is due to the loss of elastic hysteresis in the elastomer. Therefore, regardless of the magnitude of the modulus of elasticity of the material of the belt, the modulus of elasticity of the elastomeric material must be less than that of the material of the belt. The modulus of elasticity of the belt, the module

  elasticity of the tire made of elastomeric material, the thick-

  The size of the outer diameter of the tire, the size of the outer diameter of the hard roller, and the size and deformation rate of the elastomeric material (caused by the force between the rollers) can be selected in a well-known manner. to provide optimum tension profile and optimum performance of the tensioner mechanism for each

  -realization or individual application in a product.

  Although the material used for the wiper has been described as an elastomeric material, any viscoelastic material may be used for

  create the phenomenon of rolling friction. Preferably

  Preferably, the viscoelastic material is selected from a preferred group of elastomers, namely silicone rubber, which has a uniform modulus of elasticity over a

wide range of temperatures.

  In summary, a device has been described above.

  strip element drive. The device

  consists of two blocks of rotating belt element

  such as wound tape blocks 20 and 40 (FIG. 5), 61 and 76 (FIG. 6) 210 and 212 (FIG. 7), 214 and 216 (FIG. 8), for winding and unrolling between them the element gang. An endless belt, such as the belt 23 of FIG. 5, the belt 90 of FIG. 7 and the belt 11OA of FIG. 8, couples the rotating web element blocks in rotation. The belt tensioner is intended to create greater tension in the part of the endless belt that leaves

  belt tensioner only in the part that enters it.

  The belt tensioner comprises at least first and second rollers, such as the rollers 21-48 and 22 of Figure 5, the rollers 21-48 and 22 of Figure 6, the rollers 94-95, 96 of Figure 7 and the rollers 114-115, 116 of Figure 8. The first roller has a hard outer periphery and the second roller has an outer periphery of elastomeric material. The first and second rollers are pressed against each other on the opposite sides of the endless belt so that when the belt is pulled between them, the rolling friction between the rollers generates a greater tension in the

  part of the belt that leaves the tensioner.

  Although the belt tensioner of Figure 3, which has an elastic intermediate roller and two hard outer rollers, has been shown to be used in the embodiments of the invention shown in Figures 5, 6, 7 and 8, it will be understood that the belt tensioner shown in Figure 4 can be used in its place so that the device thus comprises a hard intermediate roller between two outer rollers of elastomeric material. It will also be understood that with some degradation of inversion performance characteristics, the two-roller arrangement of FIG. 2 can be used in the embodiments of FIGS. 6, 7 and 8 by removing one of the two outer rollers

  and making other appropriate changes to the

  drive and tensioner.

  Although embodiments of the invention have been described for purposes of illustration, it will be understood that various changes, modifiers and substitutions may be made or made to such embodiments without departing therefrom for that purpose. spirit of the invention such

  as defined by the appended claims.

Equations

  P. Equation A Equation AA Equation B y Equation BB Equation C R s R 'JPx dx 0n 2Wa 3WT 3 Trt)

L = -W. R E]

2 YZ

= 30 U, R l / zE

Claims (27)

  1. Device for driving a strip element, characterized in that it comprises two rotating band element blocks (30, 40, 61, 76; 210, 212; 214, 216), an endless belt ( 8, 16, 110, 23, 79, 90, 11QA) coupling between two in rotation the strip element blocks and a belt tensioner, the belt tensioner comprising at least two rollers, one of which (3, 11, 12   104, 20, 22, 93, 96, 113, 116) has an outer periphery   and the other (6, 10, 102, 107, 21, 94, 114) has an outer periphery visco-elastic, these rollers at least two in number being pressed against each other on the faces opposite of the endless belt so as to deform the viscoelastic outer periphery so that when the belt is pulled between the   rollers, the rolling friction caused by the deformation   a higher tension in the part of the belt that leaves the tensioner than in the part enter the tensioner.   2. tape drive device according to claim 1 characterized in that the belt tensioner is bidirectional and comprises at least one roller in addition to the other two rollers and said, among these rollers, first and second rollers (11, 12, 102, 107, 20, 22, 93, 96, 113, 116) are either of a first type characterized by a hard outer periphery, or of a second type characterized by an outer periphery visco- elastic and a third roller (10, 104, 21, 94, 114) is of the opposite type to that of the first and second rollers, the first and third rollers being pressed against each other on the opposite faces of the belt without   end (16, 110, 23, 79, 90, 110A) and the second and third   pebbles being pressed against each other on opposite sides of the endless belt so as to thereby deform the viscoelastic outer periphery so that,   when the endless belt is pulled into one or the other   Between the rollers, the rolling friction caused by the deformation creates a greater tension in the part of the belt that leaves the tensioner than in the part that enters it. Band-type drive device according to Claim 2, characterized in that the first and second rollers (11, 12, 20, 22, 93, 96, 113, 116) are of the type having a hard outer periphery and in that the third roller (10, 21, 94, 114) is of the type having a   visco-elastic outer periphery.   Band-type drive device according to Claim 2, characterized in that the first and second rollers (102, 107) are of the type having an external visco-elastic periphery and in that the third roller (104) is of the type having a hard outer periphery. Band-type drive device according to Claim 2, characterized in that the roller of the second type comprises a cylindrical roller (10, 102, 107, 21, 94, 114) carrying a viscoelastic band (9, 101, 106, 48, , 115).   Band-type drive device according to Claim 5, characterized in that the inside of the   viscoelastic bandage is stuck to the outer periphery top of the cylindrical roller.   Band drive device according to claim 2 characterized in that each of the rollers   is mounted on bearings with virtually no friction.   Band-type drive device according to Claim 2, characterized in that the rollers of the first type have an outer periphery which is harder than the endless belt and in that the rollers of the second type have a more elastic outer periphery. that the endless belt.   9. Device for driving strip element according to claim 2 characterized in that it comprises means (53-56) for adjusting the pressure between the first   and third rollers (20, 21) and for independently adjusting   pressure between the second and third rollers (22, 21).   Band-type drive device according to Claim 2, characterized in that the belt blocks (30, 40, 61, 76) are mounted approximately in the same plan.   Band-type drive device according to Claim 2, characterized in that the endless belt is in substantially no-slip contact with each block of element in band.   Band-type drive device according to Claim 2, characterized in that the endless belt is in substantially non-slip contact with   each strip element block on an arc of at least 75.   13. Band drive device   according to claim 12 characterized in that it comprises   at least two crazy pulleys (27, 42) and a capstan   rotary belt drive (34) guiding the conveyor belt   endless belt on such a contact arc of at least 75.   Band drive device according to Claim 13, characterized in that it comprises means (24, 25, 28, 43, 44, 45) for applying a spring load to each of the idle pulleys (27). , 42) so as to put the endless belt (23) under a pre-tension in non-slip contact with each   strip element blocks (30, 40).   15. Band drive according to the claim   14 characterized in that the idler pulleys are arranged on the path of the belt on the sides   opposite of the belt tensioner and between the   in the belt and that the belt drive capstan is disposed on the path of the belt between   the element blocks in band and on the side of the blocks of ele-   in the opposite strip to the tensioner belt.   The tape member driving apparatus according to claim 14, characterized in that the belt drive capstan (34) is positioned to engage an outer motor capstan (47). Band drive device according to claim 2, characterized in that the endless belt is in substantially non-sliding contact with   each strip element block on an arc of at least 1350.   18. Strip element driving device   according to claim 17, characterized in that it comprises   at least four belt idlers (206, 208, 64, 75) for guiding the endless belt (79) over a contact arc of at least 1350, in that first and   second idler pulleys (64, 75) with belt are position-   on the side of the endless belt opposite the side where the belt tensioner (204) is located, and third and fourth idler belt pulleys (206, 208) are positioned on opposite sides of the belt tensioner (204). belt and between the tensioner and the blocks strip element (62, 76).   19. Strip element driving device   according to claim 18 characterized in that the third   third and fourth idler pulleys are spring-loaded idlers (20, 208) for subjecting the endless belt to pre-tension so as to substantially prevent slippage between the endless belt and the blocks strip element.   20. Device for driving strip element according to claim 19 characterized in that it comprises at least one pressure roller (67) arranged to 2489-575   come to bear against the tape element <80) between strip element blocks.   21. Band drive device   according to claim 20 characterized in that it comprises   means for subjecting the pressure roller to the load of a spring (69) in the direction of the element   in band (80) so as to create a non-slip interface   between the strip element and an outer capstan (68) with motor.   Band drive device according to claim 2, characterized in that the strip element blocks (210, 212, 214, 216) are mounted coaxially with rotation approximately around the same axis.   23. Band drive device   according to claim 22 characterized in that the cour-   endless belt (90, 110A) is in substantially non-slip contact with each strip element block on a arc of at least 1800.   Band drive device according to claim 23, characterized in that it comprises at least four idler pulleys (91, 92, 99, 100, 111, 112, 118, 119) for guiding the endless belt. on a bow of contact of at least 180.   Band drive device according to claim 24 characterized in that it comprises a bidirectional capstan (97) for belt drive designed to abut against the endless belt (90). Band drive device according to claim 25, characterized in that the capstan (97) guides the endless belt (90) from the plane of a strip element block (210 or 212) to the plane. from the other block in-band element (212 or 210).   27. Strip element driving device   according to claim 24 characterized in that it comprises   a bidirectional capstan (121) designed to bear against the strip element between the blocks strip element (214, 216).