JPS63241746A - Improved tape transport cartridge - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to tape transport, and more particularly to recording and/or tape transport.
or to a device for causing movement of a magnetic recording tape with respect to a playback head. More particularly, the present invention relates to an improved tape drive system in which the tension applied to the tape varies from the beginning of the tape (BOT) to the end of the tape (BOT).
The average tension is low and uniform up to T).

Tape transport mechanisms are, of course, well known in the art. Tape transport devices of the same general type as those of the present invention are disclosed in commonly assigned U.S. Pat. No. 3,620,473, U.S. Pat. This is exemplified by the device disclosed in No. A tape transport device typically includes a tape handling mechanism, a magnetic tape capable of storing a program, a read/write head, and a drive motor.

- type of tape drive system employs a circumferential drive belt to drive the tape pack. The belt runs in a path that contacts the tape pack, and the tape is driven by a capstan. A typical circumferential belt drive system includes a spring-loaded idler that tensions the drive belt and provides the tape tension necessary to maintain the tape in contact with the read/write head and avoid tape slippage. It can have a brake and a brake to establish the rotational speed difference of the tape.

A particular problem in the prior art relates to the absolute level of tape tension and the average tape tension from BOT to EOT. but,
In practice, the tape tension increases significantly at the beginning and end of the tape, and the average tape tension is higher than the desired constant level. High tension levels in the BOT and EOT create stresses that, in severe cases, can distort the tape.

Additionally, the increased average tape tension causes wear on the tape and read/write heads, wastes power as more input is required to drive this unit, and generally reduces tape transfer from reel to reel. becomes worse.

The above problems of the prior art are overcome or alleviated by the present invention which incorporates a pair of rotary brakes into a circumferential belt drive system. A dual-rotating brake is located adjacent to the tape pack to increase separation between the drive belt and the tape near where the tape exits or joins the tape pack, and to increase the contact angle between the drive belt and the tape pack. position to increase. As a result, contact between the drive belt and the tape is concentrated at the location of maximum interlayer pressure on the tape. As a result,
A system is obtained with significant improvements and advantages of the present invention compared to the prior art.

1, 2 and 3, a tape transport unit according to a preferred embodiment of the invention is shown, with FIG. 2 schematically illustrating the path of the recording tape and drive belt. Figures 1 and 2
In the tape transport device shown in FIGS. and 3, the recording tape is housed in two reels 0.12 rotatably mounted on a cartridge base II. Depending on the direction of tape movement, one reel acts as a supply reel;
The other reel acts as a take-up reel. reel 10
,! 1 is attached to a shaft mounted on a precision ball bearing that allows the reel to rotate. According to the present invention, no driving force or braking force is transmitted to any of the freely rotating reel shafts. In addition to the reels 10 and 12, the tape transport device shown in FIGS. 1, 2, and 3 also includes a magnetic tape 14 to be transported between the reels, a drive motor I6, and a rotatable cap attached to the cartridge body 11. It includes a stan I8 and a drive belt 20 that couples the motor 16 to the capstan 18 such that the motor drives the capstan.

The tape transport attachment is also clearly visible in FIG. It includes a contacting read/write head 24.

If reel 0 is functioning as a supply reel and reel 12 is functioning as a take-up reel, the path of the recording tape 14 is from around the reel 10, across the first tape guide 26, and then through the operation of the head assembly 24. It traverses the gap, then passes a BOT/EOT photoelectric sensor, indicated generally at 28, then traverses the second tape guide and enters around the tape pack of take-up reel 12. The only transport element that contacts the tape oxidized surface on the outside of the tape pack is the read/write
Note that this is the working gap plane of the write head 24. The back side of the tape rather than the oxidized side is the tape guide 2.
Contact 6.30. The presence of special transport elements in contact with the tape oxidation surface reduces oxide wear and increases tape life.

It will also be noted that BOT/EOT sensor 28 has been omitted from FIGS. 2 and 3 to facilitate understanding of the present invention. The tape packs and elements described above are well known in the art.

Of course, if reel 12 functions as a supply reel and reel 10 is a take-up reel, the path of recording tape 14 would be reversed as described above.

The path (forward direction) of the endless circumferential drive belt 22, which is preferably an endless plastic film, e.g. a polyimide film such as KapLon or a polyester film such as Mylar, extends around a portion of the periphery of the tape pack of the reel 10. around the first rotary brake 32 (b), around the idler roller 35, around the idler roller 34 for belt tension, around the idler 33, around the second rotary brake 32 (a), around the reel 12
around part of the tape pack, capstan 18
around and return to the starting point on the tape pack of Reel IO. Brakes 32 (2L), 32 (b) are magnetic hysteresis brakes as known in the art, but could also be friction brakes. A belt tensioning idler roller 34 is rotatably mounted on a shaft at a first end of a spring loaded arm 36 and a counterweight 38 is mounted at the opposite end of the arm 36. The arm 36 is mounted on a rotatable shaft 37 mounted on a bearing 36 in a housing 39 of the base 11. The tensioning spring for arm 36 is indicated at 40. The spring 40 is a torsion spring, with one end being grounded to the base 1 at a post 42, and the other end of the spring 40 being attached to a post 44 on the arm 36.
The main body of is wrapped around the housing 39. Spring 4
0 maintains a substantially constant tension on the belt 22 as the tape 14 transitions from the beginning to the end of the tape by pressing the arm 36 and idler roller 34 in a direction that imposes a tensile load on the belt. A counterweight 38 is attached to the arm 36 to counteract fluctuations in belt tension that may result from vibrational forces experienced by the tape transport unit.
It helps to dynamically balance the The direction of transition of the belt 22 is from the supply tape reel, across the dual brake and idler/pulley system, and toward the take-up reel.

Capstan 18 is driven by motor 16 via drive belt 20. The speed of drive motor 16 can be controlled in a conventional manner using feedback from a capstan mounted tachometer. The direction of rotation of the motor, capstan, and drive belt is determined by which reel functions as the supply reel and which acts as the take-up reel.

The tape driving force is transferred from the capstan 18 to the peripheral drive belt 2.
2 and from belt 22 to the outermost layer of tape 14 on reel 10° 12. Power transmission is accomplished by the normal static friction forces present at the belt-to-carb-squeen interface and the belt-tape interface. The circumferential belt 22 is maintained at the proper tension at all times by a spring loaded belt tensioning arm 36 and a roller 34 mounted thereon. A spring-loaded belt tensioning arm and associated roller 34
It helps to compensate for small changes in the total linear distance around the belt path due to changes in the total tape length arrangement between the two reels. The frictional forces at the belt-to-capsun and belt-tape interfaces are suitable for driving the tape without significant slip even during rapid start-stop operations. FIGS. 1 and 2 were incorporated into U.S. Patent No. 4,455,000.
A comparison with FIGS. 1 and 3 of U.S. Pat. No. 4,455,001 shows that the present invention differs from the structure shown in FIG. 1 of U.S. Pat. No. 4,455,001 in the following respects. That is, (1) a pair of rotary brakes 3 rather than the single rotary brake of the prior patent;
Contains 2 (a), 32 (b): Reel 1011
2 increases the separation of the drive belt from the tape on top and increases the contact angle between the drive belt and the tape pack on each reel (the angle of U.S. Pat. No. 4,455,001 shown in FIGS. 4 and 5). (3) Establishing the desired wrap angle around brake 32(b). including an idler 35 that serves; and (4
) Idler 33 is located where the brake is located in the prior patent.
is included.

Dual brakes, namely brakes 32 (a), 32 (
The use of b) and the arrangement of these brakes with respect to tape reel 10112 are important features of the invention. 2
As a result of the presence and arrangement of the rotary brakes 32 (a), 32 (b), the magnetic tape 1 is
4, and the tape tension at the beginning of the tape and at the end of the tape is noticeably lower. Lower average tape tension and lower tension levels at the beginning and end of the tape result in longer tape life since high tension is detrimental to tape life. These low tension levels also provide several other important benefits as discussed below.

Setting the torque of a single rotation brake to obtain the desired tape tension to produce the best tape/head interface pressure is well known in tape transport systems. In the system of the invention, the total torque of the two brakes is equal to or slightly less than the torque required for a single brake, and the brake torque is divided approximately equally between the two brakes; The torque level of each brake is equal to half the torque of a single brake, or
or smaller.

6 and 7, typical tension curves are shown for bed-driven tape transport devices according to the prior art and the present invention, respectively, where the transport devices are used for the same application and use the same tape and tape reel. operated under the same conditions. FIG. 6 shows tape tension T versus tape transition from BOT to EOT.

Tape tension varies from approximately 2.4 ounces to 4.5 ounces, with a significant increase in tension as the tape approaches BOT or EOT. FIG. 6 shows an upholstery turn known in the art, often referred to as a "butterfly" or "bowtie" curve or pattern.

In the system shown in FIG. 3, the required tension is 2.
4 ounces and 2.4 of the period from BOT to EOT.
Tensions greater than ounces represent power drain and excessive wear of the tape.

Referring to FIG. 7, there is shown a tension curve for a system comparable to that of FIG. 6, but employing the dual brake configuration of the present invention. As can be seen, the absolute level of tension is much lower, ranging from 1.2 ounces to 2.9 ounces.

The curves are much flatter and closer together, but
This means that the average tape tension from BOT to EOT is low;
and close to the absolute minimum required for proper operation of the system. As shown in FIG. 7, since the average value and absolute value of the tape tension obtained by the present invention are low,
Tape life is increased and tape deformation, especially at the beginning and end of tape transition, is reduced or eliminated. The lower average tape tension results in less wear on the read/write head 24 and also reduces abrasion of particles from the head that can contaminate the tape and/or transport system. Because the power drain of the prior art is reduced, less power is required to drive the unit (ie, the unit is more efficient). Also, the more uniform interface between the tape and the read/write head facilitates tape transfer from reel to reel.

The benefits realized from the dual brake system of the present invention are unexpected and non-obvious. Although the explanation for the operation of the invention and the achievement of its several important advantages is not always fully understood, theories have been developed that provide some explanation. However, this theory is only the best currently understood and may not necessarily be correct or accurate. The invention is not limited to this theory. Two brakes 32(a), 32(b
) is the angle at which the drive belt 22 contacts the tape pack (a
), (b) are located to maximize. That is, U.S. Pat.
20,473, 3,974,982 and 4,555.0H)
, in which case the tape enters and exits the tape pack (the tape pack is the area where the tape is most relaxed on the tape pack and slippage between the drive belt and the tape is most likely to occur), and the drive belt 22 and the tape pack contact is concentrated at the rear of the tape pack, i.e. in the area of maximum interlayer pressure of the tape pack. This results in a system in which more tape mass is driven by the belt, and the instantaneous linear velocity of the tape pack is more constant.

This differs from prior art systems in which the drive belt contacts the tape pack at a smaller angle, thus driving only the first few layers of tape (i.e. driving a lower tape mass). This tends to result in uneven tape tension as the tape is wound. Tape tension is established by establishing a small instantaneous linear velocity difference between the tape exiting the payout reel and the tape entering the take-up reel. It is well known in the art to establish this instantaneous velocity difference by means of a brake placed in the path of the drive belt. In order to establish this instantaneous speed difference, the use of twin brakes in the present invention and the placement of the twin brakes to increase the angles (a), (b) will help establish a symmetrical load in the belt path. As a result, the instantaneous tape speed difference is expected to become more constant. A more constant instantaneous velocity difference results in a more constant average tape tension, especially for BO
The absolute tape tension is lower in the T and EOT regions, resulting in several unexpected advantages of the present invention.

For example, as seen in FIGS. 2 and 3, in the present invention, the angle (a) changes from a minimum of 30° to a maximum as the tape moves from initially being entirely on the reel 12 to being entirely on the reel 10. The angle (b) varies from a minimum of 20° to a maximum of 35°. In contrast, prior art single brake systems using the same tape
As the tape moves from initially being entirely on reel 12 to being entirely on reel 10, the angle (a) increases to 11).
Varying from 12° to maximum 23°, angle (b) minimum 10
It varies from 18° to a maximum of 18°. Both angles (a), (b
) is always at least 20°.
It is believed that this contributes to the advanced performance of the present invention. Although the invention has been illustrated and described, various modifications and substitutions may be made without departing from the spirit and scope of the invention.

[Brief explanation of the drawing]

1 is a top plan view of a dual-brake tape transport system according to a preferred embodiment of the present invention; FIG. 2 is a schematic diagram of the tape transport system of FIG. 1 at the beginning of tape mode; and FIG. 3 is a top plan view of the tape transport system of FIG. 1 at the end of tape mode. FIG. 1 is a schematic diagram of a tape transport device, FIGS. 4 and 5 are schematic diagrams of a prior art single brake tape transport device at the beginning and end of tape mode, respectively, and FIG. 6 is a typical prior art tape transport device. FIG. 7 is a graph illustrating an exemplary improved tape tension curve for the tape transport system of the present invention. 10, l 2. , , reel, 14. ,,magnetic tape, 16. ,, drive motor, +8. ,, Capstan, 20. ,, drive belt, 26.30
13. Tape guide, 28. ,, sensor, 32 (a
), 32 (b), , brake, 33.35, ,
Idler. Procedural Amendment 411.3 ≠ 5//8 Sketch Cartridge 3, Person Making Amendment 4, Agent

Claims (1)

[Claims] 1. A tape transport device, comprising: a base on which a tape transport element is mounted; a first tape transport means rotatably mounted on the base; a first tape transport means rotatably mounted on the base; a second tape transport means attached to the tape transport means; magnetic tape means forming a tape pack on each of the tape transport means and extending between the tape transport means to transfer tape between the tape transport means; drive belt means for contacting said tape pack in each of said second tape transport means to transfer tape between said first and second tape transport means; drive means for said drive belt means; adjacent to said first tape transport means; a first rotary brake means adjacent to said first tape transport and in contact with said drive belt means; a first rotary brake means adjacent to said second tape transport in contact with said drive belt means adjacent to said second tape transport means; 2 rotational braking means; the first braking means is connected to the drive belt means and the first rotary braking means;
a second brake means is positioned with respect to said first tape transport means to establish a first predetermined angular relationship between said drive belt means and said second tape transport means; positioned to establish a second predetermined angle. 2. said first braking means, said second braking means and said drive belt means maintain the least varying tension in said first braking means over a majority of the transition of said tape means between said first and second tape transport means; and a second tape transport means, interacting to establish said tape means between said tape transport means and said second tape transport means. 3. The first braking means, the second braking means and the drive belt means control the first and second tape transport means for most of the transition of the tape means between the first and second tape transport means. 2. The tape transport apparatus of claim 1, wherein the tape transport apparatus interacts to establish a substantially constant tension in said tape means therebetween. 4. The first braking means is configured to concentrate the contact area between the drive belt means and the tape on the first tape transport means in an area of maximum intermediate layer pressure of the tape in the first tape transport means. 2. The tape transport of claim 1, wherein the second brake means is located to concentrate the area of contact between the drive belt means and the tape on the second tape transport means in an area of maximum interlayer pressure. Device. 5. The first braking means and the second braking means are positioned to establish an angle of at least 20° between the drive belt and the tape in the first and second tape transport means. Tape transport device. 6. The first braking means has an angle of about 30 degrees to about 33 degrees.
positioned with respect to said first tape transport means to establish an angle of about 35° to 20°, said second braking means establishing an angle of about 35° to 20° as said tape transitions between said first and second tape transport means. 2. The tape transport device of claim 1, positioned relative to said second tape transport means to establish an angle. 7. The tape transport device according to claim 1, wherein the torques of the first and second braking means are substantially equal. 8. A total braking torque is selected to establish a predetermined desired tape tension and a predetermined pressure between said tape and the read/write head, and a torque of each of said first and second braking means. 2. The tape transport device of claim 1, wherein the set value is less than or equal to half of the total brake torque.