Background of the Invention

Field of the Invention

This invention relates generally to the field of magnetic tape transport systems, and, more particularly, to a high-performance tape path arrangement for such systems.

Related Art

In the course of developing various systems for the storage of data, data processing systems have traditionally utilized magnetic tape as a data storage medium. Typically, the magnetic tape is contained in an appropriate cartridge to facilitate handling of the magnetic tape while in use as well as to protect the tape while in storage. An example of such a magnetic tape which has found applications in both the audio recording and computer industries is die data cartridge form as defined by American National Standard Institute

(ANSI) Standard X3.180-1990. This cartridge has a single supply reel of magnetic tape that has a tape leader block attached to the free end of the tape.

The IBM Model 3480 tape drive ("IBM" is a registered trademark of

International Business Machines Company) utilizes this cartridge. Due to the prevalence of the 3480 tape drive system in the computer and data processing industries, this magnetic tape cartridge has become known in the industry as the 3480-type cartridge.

In common tape drive systems the magnetic tape cartridge in which the magnetic media is enclosed is inserted into a tape transport system. The magnetic tape is then wound and rewound between a supply reel contained within the tape cartridge and a take-up or machine reel in the tape transport system. The tape is transported along a tape path which brings the tape into contact with, or adjacent to, a magnetic tape head located along die tape path. Magnetic tape heads used in present-day tape drive systems are multi-track tape heads having separate read and write elements associated with each data track on the magnetic tape. This enables multi-track magnetic tape heads to read and write several streams of data (one per track) simultaneously. The magnetic tape is typically guided past the read/write head by air bearings which provide an interface of forced air with the magnetic tape to lower friction forces between the tape and bearing surface.

Examples of magnetic tape drive systems which store 18 tracks of data on the half-inch magnetic tape housed in the 3480-type cartridge are the

StorageTek 4480 tape drive system, available from Storage Technology Corporation, Louisville, Colorado, U.S.A., and the IBM 3480 tape drive system, available from IBM Corporation, Armonk, New York, U.S.A. Examples of magnetic tape drives which will store 36 tracks of data on the same half-inch magnetic tape are the (not yet publicly available but soon to be released) StorageTek 4940 and 4490 tape drive systems, manufactured by Storage Technology Corporation; and die IBM 3490 tape drive system, manufactured by IBM Corporation.

Recently, there has been a great demand for increasing the data Λroughput of magnetic tape transport systems used in conjunction with high-speed digital computers. In order to utilize the high-speed capabilities of these computers, it is necessary to increase the amount of data stored on a

agnetic tape and to increase the speed at which the data is written to or retrieved from the magnetic tape media.

One improvement which has been made to achieve these goals has been the reduction in tape thickness. This improvement increases the amount of data which is stored in a single magnetic tape cartridge without changing the widdi of the tape. Changes in tape width generally require a reconfiguration of the tape transport system. By increasing the amount of tape accumulated on a single reel, the amount of data which is stored in a single magnetic tape cartridge is also increased. By increasing the amount of data stored in a single magnetic tape cartridge, die number of cartridges which must be loaded into, transported, and unloaded from a tape transport to transfer a given amount of data is decreased. By eliminating the time required to perform the mechanical loading and unloading of additional tape cartridges, he overall data throughput of the tape transport system is increased.

However, reducing the thickness of the magnetic tape greatly reduces its strength. Conventional tape drive systems, such as those mentioned above, apply a biasing load of approximately 3 grams to the edge of d e tape to guide and control the tape as it moves from the supply reel to the take-up reel. This loading has been successfully used in conventional tape transports to guide and control standard film magnetic tapes which are presently used in die industry.

Standard film magnetic tapes are .001 inches (1 mil) thick. However, applying a tape edge loading of this magnitude to thin film magnetic tapes has been found to result in substantial tape wear. Thin film magnetic tapes generally have thicknesses in the range of .0003 to .0007 inches (.3 to .7 mils). This reduces the overall life expectancy of the thin film magnetic tapes and increases the potential for read/write errors. In addition, widi die advent of magnetic tapes which are progressively thinner, tape buckling and loss of control may also occur. For example, it has been found

that conventional tape drive systems are unable to support 0.3 mil thick magnetic tapes without causing excessive tape wear and experiencing loss of tape control.

In addition to reducing the thickness of the magnetic tapes, other data storage technologies have been advanced to increase the data throughput of tape transports. Of particular relevance is the advance in magnetic tape head technology to increase, among other things, the track density of die magnetic tapes. Track density is defined as die number of data tracks per unit widtii of magnetic tape. Two characteristics associated with track density are track widtii, defined as the actual width of an individual data track; and track pitch, defined as the distance from the center of one data track to the center of a neighboring data track. As magnetic tape head size decreases, the track pitch and track width of the magnetic tapes is decreased, tiiereby increasing track density.

An example of the increasing track density can be seen by comparing the StorageTek 18-track 4480 tape drive system with die StorageTek 4940 36-track tape drive system. Both systems support die half-inch magnetic tape contained in die 3480-type cartridge. The magnetic tape used in die 4480 18-track tape drive system has a track pitch of approximately 630 μm and a track widtii of approximately 540 μm. The magnetic tape used in die 4940

36-track tape drive system has a track pitch of approximately 315 μm and a track widdi of approximately 285 μm. Thus, the track width of the 36-track system is approximately half the track width of the 18-track system. Also, the distance between data tracks in the 36-track system is approximately a third of die distance between the data tracks in die 18-track system.

This increased track density requires the magnetic tape in the 36-track tape drive to be guided with stricter tolerances across the magnetic tape head

to prevent lateral tape movement of the tape relative to the magnetic tape head. If lateral movement occurs, data may be lost in the reading and writing of the tape. Thus, increasing track density requires a corresponding increase in the accuracy with which the magnetic tape is guided and controlled. Presently, conventional tape drive systems guide magnetic tapes with a tape movement accuracy in the lateral direction of approximately ± .0003 inches at the magnetic tape head. This accuracy has been found to be insufficient to guide magnetic tapes in tape transport systems supporting track densities which are greater tiian or equal to those of the 36-track systems discussed above.

In addition to the above technological advances in magnetic tapes and magnetic tape heads, additional improvements are desired to increase the data throughput of tape transport systems. In particular, it is desirable to increase die speed at which the magnetic tape is driven through die tape transport system. Conventional tape drive systems presently move the magnetic tape at approximately 2 meters per second (m/s) while reading and writing data to the tape. When rewinding a magnetic tape from the take-up reel back to the supply reel, conventional tape drive systems transport the tape at approximately 6 m/s. Increasing the speed at which the tape travels past the magnetic tape head increases the data transfer rate of the system. This directly increases the speed at which the associated digital computers may operate. In addition, increasing the rate at which d e magnetic tape is rewound onto die supply reel after the data transfer has been completed decreases the time in which die tape cartridge is in the tape transport. Thus, increasing the speed at which a magnetic tape is transported through the system increases die data diroughput of the tape transport system by increasing the number of cartridges which may be processed by the tape transport in a given unit of time.

Another factor which contributes to the data diroughput of a tape transport is the tape threading mechanism. The tape threading mechanism

must not only thread the magnetic tape through the tape transport system as quickly as possible, it must do so with sufficient sensitivity to avoid damaging the tape. This is particularly true for thin film magnetic tapes having a tape thickness of 0.3-0.7 mils. In addition, the tape threading mechanism must control the velocity of the tape as the direction of the tape is changed during die threading process to avoid excess tape from being retrieved from the supply reel causing undue slack (and subsequently, undue tension) to occur in the tape. Thus, it is desirable to increase the data throughput of die tape transport system by improving the capability of the tape transport system to quickly control the variations in the tape movement while efficiently threading thin film, high density magnetic tapes onto a tape transport.

The read and write signals generated and received by the magnetic tape head are typically channeled dirough an electronic read/write pre-amplifier card. The read/write pre-amplification card performs well known preamplification functions on the read signals received from die magnetic tape head. This is necessary due to die relatively small amplitude of die read signals with respect to he lengtii of the interconnecting cable. Conventional tape drive systems include magnetic tape heads which have a connector fitting on the magnetic head. One end of an electrical cable is connected to die connector fitting and the other end of d e electrical cable is attached to a connector on the read/write pre-amp card. Since the read/write pre-amplification card is not located adjacent or proximate to die magnetic tape head, this cable can be up to 2 feet in length in some conventional tape drive systems.

As the widtii of magnetic tape tracks decreases, the magnitude of the electrical signals produced by such reduced size magnetic tape read heads are also reduced. As the amplitude of tiiese electrical signals is decreased, it is desirable to decrease die lengtii of the electrical cable(s) which connect the

magnetic tape head to the read/write pre-amp card. Thus, it is desirable to have a shorter distance between the magnetic tape head and the read/write pre-amp card to reduce the attenuation of the read signals prior to their reaching die card. Shorter distances also reduce die amount of noise which is introduced along the length of the cable. In addition, it is also desirable to decrease die number of interconnections which must take place between cables and components to transfer the read signals to the read/write pre-amplification card. Each connector introduces potential noise and signal loss.

Another characteristic of tape transport systems which affects data diroughput is die overall length of the tape path from the supply and take-up reels to the magnetic tape head. A tape path with a short distance has less capacity to gain the necessary lateral position control over the magnetic tape prior to it passing the tape head. Thus, conventional tape transport systems control the lateral positioning of the tape by applying greater tape edge forces in a shorter distance. This causes excessive wear and damage to thin film magnetic tapes. This problem is exacerbated widi the advent of narrower magnetic data tracks, since greater accuracy in the control and guidance of die magnetic tape is necessary in systems implementing such tape formats. Thus, conventional tape path systems are incapable of obtaining the necessary control over thin film magnetic tapes, and die means of control conventionally used tends to damage die thin film tapes.

What is needed ti erefore, is a tape transport system which is capable of accurately and efficiently tiireading, transporting, and rewinding high-density, tiiin film magnetic tapes at very high speeds.

Summary of the Invention

The present invention is a high performance tape path system. The high performance tape path system is comprised of a number of tape guidance devices which provide varying levels of control and guidance to the magnetic tape as it travels along a tape path between a supply reel and a take-up reel.

The arcuate tape path has a magnetic tape head assembly at a central position. On each side of the magnetic tape head assembly are fine tape guidance devices which provide precise and accurate control of die magnetic tape. Adjacent to each of the fine tape guidance devices along die tape path are tape cleaner block assemblies which are used to clean the tape as it approaches and departs the area of the tape head. Adjacent to each of the tape cleaner block assemblies are coarse tape guidance devices which provide the initial control and guidance of the magnetic tape.

The high performance tape path system is electrically and mechanically coupled to a read/write pre-amplification card via two electrical connectors.

The use of a parallel latching device enables these two connectors to be connected and disconnected widi a single mechanical movement. This places the pre-amp card as close as possible to the magnetic tape head. The high performance tape path system is coupled to the tape transport in which it operates via two pneumatic fittings and three electrical connectors. One pneumatic fitting is dedicated to providing pressurized air dirough a pneumatic distribution system to die various tape guidance devices and magnetic tape head. The other pneumatic fitting is dedicated to providing a vacuum to die tape cleaner assemblies to remove debris from the tape path. The three electrical connectors provide all electrical connections between the high performance tape path system and die tape transport. All components related to the high performance tape path system are mounted on or coupled to a

sub-deck, making the high performance tape path system a modular unit which is easily removable from the tape transport.

An advantage of the present invention is that it can support thin film magnetic tapes having a tape thickness in the range of 0.3-0.7 mils. In addition, the present invention is capable of handling standard film magnetic tapes which are presently used in the industry.

A further advantage of the present invention is the ability to provide tape edge guidance at the tape head with a lateral positional accuracy of less tiian ± .25 mils, resulting in a total tape movement in the lateral direction of no more than .5 mils. This enables the high performance tape path system to implement magnetic tape heads which are capable of writing greater than 36 tracks of data to a half-inch magnetic tape.

A further advantage of die present invention is the increased radius of die arcuate tape path. This curvature reduces die amount of tape edge loading required to guide die magnetic tape, thereby enabling the present invention to gently guide and support thin film magnetic tapes traveling at high speeds widiout causing excessive tape wear.

A further advantage of die present invention is the location of the tape transducer closer to die supply reel. This enables the present invention to provide die tape threading mechanism with tension feedback to stabilize the magnetic tape faster than in conventional tape drive systems. This enables the tape threading mechanism to more quickly respond to variations in the tape movement.

A further advantage of the present invention is the ability to provide tape cleaning proximate to and at both sides of the magnetic tape head. This

reduces die number of data transfer errors and improves the error recovery capability of the tape transport.

A further advantage of the present invention is the location of the read/write pre-amp card adjacent to the tape head assembly. It has been found that, as the magnetic tape data tracks become narrower and their signals become fainter, the relative position of the read/write pre-amp card and magnetic tape head as well as the magnetic head assembly configuration used in conventional tape drive systems interfere with the successful implementation of more advanced magnetic tape heads. This reduces the distance that the read signals have to travel prior to reaching the read/write pre-amp card, reducing attenuation and signal loss. In addition, die present invention utilizes a magnetic tape head widi an integral flex circuit coupled to connectors located on the bottom of the sub-deck for connection to the read/write pre-amplifier card. This reduces die number of electrical connections between the magnetic head and read/write pre-amp card. Also, this shorter distance enables the present invention to support magnetic heads which produce extremely faint read/write signals by preventing attenuation and noise disturbances.

A further advantage of the present invention is the overall length of the tape path from the supply and take-up reels to the magnetic tape head. A tape path with a short distance has more difficulty in gaining the necessary control over the magnetic tape prior to it passing the tape head. Thus, conventional tape transport systems control the tape with a greater application of forces in a shorter distance which causes excessive wear and damage to tiiin film magnetic tapes. This problem is exacerbated widi die advent of narrower magnetic data tracks, since greater accuracy in the control and guidance of die magnetic tape is necessary in systems implementing such tape formats. Conventional tape drive systems attempt to achieve these guiding tolerances by applying much greater tape edge loading. The use of gentler compliant

guides along a portion of the 4940's tape path, coupled with the longer tape path length, provides accurate tape guiding and lower wear rates as compared to conventional systems. The present invention, by providing a longer tape path with gentler compliant guides controls and guides thin film magnetic tapes at significantly greater speeds than conventional systems without causing tape wear or damage.

In addition to increasing the speed at which a magnetic tape is threaded, transported, and rewound, odier characteristics of the tape transport have been considered to increase data throughput. One particular area has been the operational efficiency of he system regarding repair and maintenance. Conventional tape transport systems typically have a tape path which is semi-fixed in die tape transport system. That is, the components which establish the tape path from the supply reel to the take-up reel are dispersed throughout the tape transport and are individually removable. Tape transports having tiiis type of configuration are difficult and time-consuming to maintain and repair. Typically, a tape transport is rendered inoperable during the repair and maintenance of a single tape path component. As a result, the data throughput of the tape transport is adversely affected by this type of configuration.

A further advantage of die present invention is die modular nature of its construction. The entire tape path is located on a removable modular tape deck which also includes the read/write pre-amp card. This modular design enables quick repair and maintenance of the high-performance tape path system enabling a technician to remove the tape deck by disconnecting two pneumatic and two electrical connections. This will enable the tape drive system to remain operational for a greater length of time by reducing die impact of an inoperable tape path system component to the time it takes to replace such a single modular tape path unit. Thus, the data throughput of die

tape transport is not impacted by die repair and maintenance of the tape path system components.

The high-performance tape path system of the present invention is therefore able to support thin film, high-density magnetic tapes at 4 m/s when transferring data to and from the magnetic tape. This results in a data transfer rate which is approximately twice the data transfer rate of conventional tape transport systems. In addition, the present invention is capable of transporting tapes at 10 m/s when data is not being transferred to/from die tape (for example, during the rewinding of the tape). This is significantly greater than the rewind speed of conventional tape transport systems.

Further features and advantages of the present invention as well as the structure and operation of various embodiments of die present invention are described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit of a reference number identifies the drawings in which the reference number first appears.

Brief Description of the Figures

The present invention will be described with reference to the accompanying drawings, wherein:

Figure 1 is a perspective view of a tape transport system main deck illustrating the location of die major components, including the high performance tape path system of the present invention;

Figure 2 is a top perspective view of he preferred embodiment of die high performance tape path system of the present invention;

Figure 3 is a simplified top view of the high performance tape path system;

Figure 4 is an exploded view of the high performance tape path system illustrating those components mounted on the top surface of the high performance tape path sub-deck;

Figure 5 is a bottom perspective view of die high performance tape path system with the read/write card omitted for clarity;

Figure 6 is an exploded bottom perspective view of the high performance tape path system illustrating those components mounted on die bottom surface of the high performance tape path sub-deck; and

Figure 7 is a simplified diagram illustrating the potential tape movement experienced at the air bearing gap.

Detailed Description of the Preferred Embodiments

Table of Contents

I. Introduction

II. Tape Transport Architecture III. Tape Path System Overall Architecture

IV. Tape Guidance Devices

A. Initial Tape Guidance Devices

B. Coarse Tape Guidance Devices

C. Fine Tape Guidance Devices D. Tape Guidance Device Locations

V. Tape Cleaner Assemblies

VI. Tape Tension Transducer

VII. Pneumatic Distribution

VIII. Magnetic Tape Head Assembly IX. Electrical Interface

I. Introduction

The present invention is a high-performance tape path system capable of achieving tape speeds which are substantially greater than conventional tape path systems while guiding die tape in a gentler manner. The present invention is capable of supporting high-density magnetic tapes which are

.0003-.0007 inches in thickness with greater control and sensitivity than conventional tape transport systems. The high-performance tape path system achieves this increased accuracy and control without causing substantial tape wear or damage to the tape.

The high-performance tape path system of the present invention is a single modular unit which includes a platform on which all the components associated with the tape path system are mounted or attached, including a read/write pre-ampliation card, and pneumatic and electrical distribution systems. The high-performance tape path system of the present invention achieves this increased operational capability by improving various components of the tape path system and relating these components in such a manner that their contribution to the overall tape path system design is optimized.

77. Tape Transport Architecture

Figure 1 illustrates a top perspective view of a tape transport 100 illustrating the relative position of the major components of the tape transport, including a high-performance tape path system 110 of the present invention. Figure 1 further illustrates the position of tape path system 110 relative to a tape threading arm 106, a supply reel 102 located in a magnetic tape cartridge 103, and a machine or take-up reel 104. When a magnetic tape is inserted into tape transport 100, tape threading mechanism 106 attaches to a leader block of the magnetic tape cartridge and direads the magnetic tape in an arcuate path around high-performance tape path system 110 to take-up reel 104.

777. Tape Path System Overall Architecture

Figure 2 illustrates a top perspective view of the preferred embodiment of the high performance tape patii system 110 of the present invention. Figure 3 illustrates a simplified top view of high performance tape path system 110. Referring to Figures 2 and 3, a general description of die major components of tape path system 110 is now discussed. All components relating to high performance tape path system 110 are integral with, mounted

on, or attached to, a read/write sub-deck 202. Below read/write sub-deck 202 is a read/write pre-amplification card 204. Read/write pre-amplification card 204 is also mechanically coupled to sub-deck 202 via support columns 224, and is electrically connected to the components on sub-deck 202 (discussed below).

In the preferred embodiment, there are eight major components of tape path system 110 which guide and control the magnetic tape as it travels along a tape path 302. Following tape path 302 (shown in Figure 3), the first component of tape path system 110 diat the magnetic tape interfaces with is an initial tape guidance device 208. The magnetic tape then continues to travel along tape path 302 until it comes under die control of a coarse tape guidance device 210. The magnetic tape is then cleaned by a tape cleaner assembly 212. Lastly, the magnetic tape passes a fine tape guidance device 214. Coarse tape guidance device 210 and fine tape guidance device 214 provide increasing control over the movement of die magnetic tape as it travels along tape path 302 from the supply reel to the magnetic tape head assembly 216. This enables tape path system 110 to achieve the necessary accuracy of tape movement control of the magnetic tape as it passes over magnetic tape head assembly 216.

Components which are functionally similar to coarse tape guidance device 210, tape cleaner assembly 212, and fine tape guidance device 214 are located on die opposite side of magnetic tape head assembly 216. These include a fine tape guidance device 218, a tape cleaner assembly 220, and a coarse tape guidance device 222. This side of tape path system 110 is referred to as the take-up reel side since the magnetic tape is transferred between take-up reel 104 and magnetic tape head assembly 216. The opposite side of tape path system 110 is referred to as die supply reel side since the magnetic tape is transferred between supply reel 102 located within magnetic tape

cartridge 103 and magnetic tape head assembly 216. This mirror image configuration of components on the supply reel and take-up reel sides enables tape path system 110 to optimally read and write data to the magnetic head in both directions (discussed further below).

Referring to Figure 2, die mechanical relationship between a read/write pre-amplification card 204 and sub-deck 202 is discussed. The executed functions and interface are described below. Pre-amplification card 204 is configured to have a shape and size which fits within support columns 224. Support columns 224 of the read/write sub-deck 202 are likewise configured to hold read/write pre-amplification card 204 widi clips 232. Each support column 224 has a support column read/write card recess 226 which provides a surface against which the read/write pre-amp card 204 is held. A clip 232 attached to each support column 224 in a horizontal clip recess 228 and a support column vertical slot 230.

Thus, by physically attaching read/write pre-amplification card 204 to sub-deck 202 and by mounting all components relating to the guidance and control of the magnetic tape along the tape path, tape path system 110 is an integral, modular, removable unit. It is common to involve the read/write pre-amplification card 204 in the troubleshooting of die tape path system and its components. By having the read/write pre-amplification card 204 and sub-deck 202 in a single, modular unit, the complete assembly may be removed from the tape transport system for repair and maintenance. The high-performance tape path system 110 may then be replaced by another high-performance tape path system during this repair and maintenance period. Thus, die data diroughput of the tape transport system, in which the high-performance tape path system 110 is contained, is increased due to the reduction in downtime during repair and maintenance. There are additional benefits to locating die read/write pre-amplification card 204 in such close

proximity to the magnetic tape head assembly 216. These additional benefits are discussed in detail below.

IV. Tape Guidance Devices

Referring to Figures 2 and 3, in the high performance tape path system 110 of the present invention, the magnetic tape is primarily controlled by the five tape guidance devices discussed above: initial tape guidance device 208, coarse tape guidance device 210, fine tape guidance device 214, fine tape guidance device 218, and coarse tape guidance device 222. As will be discussed in detail below, these tape guidance devices have different configurations and perform different functions to control the movement of the magnetic tape as it travels through high performance tape path system 110. These different configurations and functions are dependent upon die location of the tape guidance device along die tape path in high performance tape path system 110. All five tape guidance devices contain air bearings which provide a cushion of air on which the magnetic tape travels.

The read/ write sub-deck 202 has raised platforms on which the pneumatic tape guidance devices are mounted. The pneumatic tape guidance devices receive pneumatic pressure and/or vacuum from pneumatic source(s) through a pneumatic distribution system. This pneumatic pressure/vacuum is fed dirough die bottom surface of read/write sub-deck 202 to supply ports on the top surface of the sub-deck 202 on the associated raised platforms.

The five pneumatic tape guidance devices fall into three categories according to die function diat they perform. The first category of tape guidance devices have, as tiieir primary function, the traverse or radial positioning of die magnetic tape as it travels along tape path 302. This first category of tape guidance devices includes initial tape guidance device 208.

Initial tape guidance device 208 performs the initial traverse positioning of the magnetic tape as it leaves the supply reel and begins to travel along tape path 302 on the high performance tape path system 110.

The second category of tape guidance devices have as their primary function the initial lateral stabilization of the magnetic tape as it begins its travel along tape path 302. This second category of tape guidance devices includes coarse tape guidance device 210 and coarse tape guidance device 222. Coarse tape guidance device 210 performs the initial lateral stabilization of the magnetic tape as it comes from supply reel 102. Coarse tape guidance device 222 performs the initial lateral stabilization of the magnetic tape as it comes from take-up reel 104.

The third category of tape guidance devices have as their primary function the accurate and precise lateral and transverse guidance and control of the magnetic tape for proper alignment with die magnetic tape head 216. This category of tape guidance devices includes fine tape guidance device 214 and fine tape guidance device 218. Fine tape guidance devices 214 and 218 are required to provide the most accurate guidance and control of the magnetic tape since they are located closest to the magnetic tape head 216. Each of these pneumatic tape guidance devices is discussed below in accordance with the above categories.

A. Initial Tape Guidance Devices

Initial tape guidance device 208 is die first major component of this high performance tape path system 110 which die magnetic tape encounters once it has left the supply reel 102. As a magnetic tape is unwound from a supply reel within a magnetic cartridge, die exit angle of die tape changes as die amount of magnetic tape remaining on the supply reel decreases. Initial

tape guidance device 208 provides the optimum support arc for positioning of the magnetic tape to avoid having the magnetic tape come in contact with the leader block retaining walls of the magnetic tape cartridge as the exit angle of the magnetic tape changes.

Referring to Figure 4, initial tape guidance device 208 is mounted on platform 408 of sub-deck 202. Initial tape guidance device 208 includes an air bearing 402 which is pneumatically coupled to a pneumatic source through die pneumatic port 431 in platform 408. Pneumatic port 431 extends through platform 408 and sub-deck 202 to couple air bearing 402 to a pneumatic distribution system (discussed further below). Initial guidance device 208 is also comprised of an air bearing cover 404 which is placed over air bearing 402. Air bearing cover 404 includes a flange which extends over the orifices on the front surface of air bearing 402. Air bearing cover 404 provides a fixed surface under which die magnetic tape is initially threaded by tiireading arm 106. Air bearing screws 406 are used to secure air bearing cover 404 and air bearing 402 to platform 408.

Thus, as shown in Figure 1, placing initial tape guidance device 208 in close proximity to supply reel 102 and magnetic tape cartridge 103 enables die high-performance tape path system 110 to initially position the magnetic tape for optimal performance and to provide an initial fixed padi between air bearing cover 404 and sub-deck 202 top surface.

B. Coarse Tape Guidance Devices

After the magnetic tape is initially positioned by initial tape guidance device 208, die magnetic tape then travels along tape path 302 until it comes under die control of coarse tape guidance device 210. Initial tape guidance device 208 and coarse tape guidance device 210 are positioned relative to each

other and shaped such that the magnetic tape smoothly transitions from one to the other and is properly positioned when it comes in contact with coarse tape guidance device 210.

Referring to Figure 4, coarse tape guidance device 210 is a bi-compliant tape guidance device having an air bearing 412 and two spring assemblies 422, 424. Spring assemblies 422,424 provide a compliant, mechanically-induced, bias load to either die top or bottom edges of the magnetic tape as it travels along tape path 302 past air bearing 412.

Upper spring assembly 422 applies compliant tape edge loading to the top edge of die magnetic tape. Lower spring assembly 424 applies compliant tape edge loading to die opposite (bottom) edge of die magnetic tape. Both spring assemblies 422, 424 have a number of flat springs with ceramic guide buttons at their distal ends which contact the magnetic tape. The bi-compliant tape guidance devices are described in a commonly owned U.S. patent application, entitled "Bi-compliant Tape Guide, " filed on August 20, 1993

(attorney docket number 7509.017), naming as inventors Barry K. Spicer, Christian A. Todd, Donovan M. Janssen, and Richard W. VanPelt, herein incorporated by reference in its entirety. In a preferred embodiment of die present invention, the upper spring assembly 422 and lower spring assembly 424 each have 4 flat springs. This number of flat springs was determined to provide optimal coarse control over the magnetic tape given the tape movement variations which are experienced by the magnetic tape coming from the supply reel. However, as one skilled in die relevant art will recognize, any number of springs may be used which meets the requirements of a given application.

As illustrated in Figure 4, dual air bearing 412 is positioned over a bottom plate 418 and is attached to platform 438 on read/write sub-deck 202.

-01.

Air bearing 412 is pneumatically coupled to a pneumatic source (not shown) through pneumatic port 435 in sub-deck platform 438. Upper spring assembly 422 is attached to the top of air bearing 412 and secured with upper spring assembly cover 426. The four flat spring mounted guide buttons of upper spring assembly 422 extend out over the air ports of air bearing 412 to contact the top edge of the magnetic tape.

As shown in Figure 4, lower spring assembly 424 is not positioned below air bearing 412. Instead, lower spring assembly 424 is positioned such diat the spring elements approach the bottom of the tape path from the opposite side of the magnetic tape path 302. Lower spring assembly 424 is secured in a lower spring assembly recess 436 in read/write sub-deck 202. Lower spring assembly 424 is secured to sub-deck 202 by lower spring assembly cover 428 and lower spring assembly cover screws 434. From tiiis position in sub-deck 202, the four flat springs of lower spring assembly 424 extend to below tape path 302 to apply a compliant biasing load to the bottom edge of the magnetic tape.

The use of compliant flat springs in tape guidance devices is known in die art. However, tiiere are a number of disadvantages associated with the use of conventional compliant flat springs. First, the accuracy of the biasing load which is applied to the magnetic tape edge is determined by die flatness of the spring. Typically, the tolerance of the spring flatness can be held only to within ±5 mils. This causes large variations and limited control in tape edge loading. These loading variations result in excessive wear to thin film magnetic tapes which are .7 mils or less in thickness. In addition, die large variations and limited control provided by conventional flat springs have been found to cause thin film magnetic tapes to buckle. This is due to the large variation in tape edge loading by die guide button. As a result, the tolerances of the spring flatness are critical when guiding thin film magnetic tapes.

The upper and lower spring assemblies 422,424 of bi-compliant coarse tape guidance device 210 of the present invention apply an accurate predetermined tape edge loading on the top and bottom edges of the magnetic tape. This tape edge loading is the minimum loading necessary to provide the desired initial guidance at this location along tape path 302. In addition, die variations in applied load from one spring element to the next has been essentially eliminated in the coarse tape guidance device 210 of the present invention. These benefits have been achieved by presetting the applied loads of the upper and lower spring assemblies 422,424 in a process described in a commonly owned U.S. patent application, entitled "Compliant Guide

Assembly For a Magnetic Tape Transport Including a Method and Fixture For Calibrating the Same," filed on September 17, 1993 (attorney docket number 1411.0350000), naming as inventors Wayne E. Church, Donovan M. Janssen, and Willis A. Straight, herein incorporated by reference in its entirety.

In the preferred embodiment of die present invention, die metiiods employed in die above-referenced patent application have been used in all flat spring assemblies used in the high-performance tape path system 110. These will be discussed below widi reference to their associated tape guidance device.

The use of a bi-compliant tape guidance device which applies a precise and known bias load to either edge of a passing magnetic tape enables the high performance tape path system 110 of the present invention to considerably reduce the variations in tape movement. The total tape movement experienced at a point in tape path 302 immediately before coarse tape guidance 210 is ± .008-.010 inches. Variations in tape movement after the magnetic tape passes the last flat spring element of coarse tape guidance device 210 is approximately ± .003 inches. These achievements in tape guidance are achieved in the high-performance tape path system 110 while applying the

minimum load necessary to the tape edges, resulting in minimal wear to the tape.

Referring to Figure 4, coarse tape guidance device air bearing 412 is one of two air bearings which comprise dual air bearing 410. Dual air bearing 410 is a single air bearing which is separated into two sections: air bearing 412 for the coarse tape guidance device 210 and air bearing 414 for the fine tape guidance device 214. Dual air bearing 410 has a recess 444 which separates coarse tape guidance device air bearing 412 and fine tape guidance device air bearing 414. Positioned in recess 444 is a tape cleaner assembly 212 (discussed below).

The previous discussion has been directed to coarse tape guidance device 210, which is positioned on the supply reel side of high-performance tape path system 110. Coarse tape guidance device 222, which is positioned on die take-up reel side of high-performance tape path system 110, performs the same functions and is comprised of similar elements as coarse tape guidance device 210. Coarse tape guidance device 222 is comprised of an air bearing 464, an upper spring assembly 474, and a lower spring assembly 476. Upper spring assembly 474 is secured to the top surface of air bearing 464 by an upper spring assembly cover 478 and upper spring assembly cover screws 484. Lower spring assembly 476 is secured in a lower spring assembly recess

488 in sub-deck 202 by a lower spring assembly cover 480 and lower spring assembly cover screws 486.

Air bearing 464 is attached to fixed tape guide 466 by dual air bearing screws 482. Air bearing 464 is then attached to platform 490 and receives pneumatic pressure/vacuum through pneumatic port 439 on sub-deck platform

490. Dual air bearing 460 is comprised of coarse tape guidance device air bearing 464 and fine tape guidance device air bearing 462. Dual air bearing

460 has a recess 494 in which tape cleaner assembly 220 is positioned (discussed below).

One significant difference between coarse tape guidance device 210 and coarse tape guidance device 222 is the number of flat spring elements comprised in the respective upper and lower spring assemblies. Upper and lower spring assemblies 474, 476 of coarse tape guidance device 222 have six flat spring elements each. Upper and lower spring assemblies 422, 424 of coarse tape guidance device 210, however, have four spring elements each. The additional spring elements which are used in coarse tape guidance device 222 are due to the tape movement variations which are experienced by the magnetic tape which is received from the take-up reel versus the supply reel. Thus, to achieve the same tape movement tolerance of ± .003 inches of the magnetic tape as it leaves the last spring element of coarse tape guidance device 222, additional spring elements were found to be necessary. Thus, as one skilled in the relevant art would know, die particular number of spring elements which are used in coarse tape guidance devices 210,222 is a function of the particular application in which the high performance tape head system 110 is used and die stability of the magnetic tape as it comes from the supply and take-up reels.

In summary, coarse tape guidance devices 210,222 provide accurate, predetermined, tape edge loading to the magnetic tape as it travels from both the supply reel and die take-up reel along tape path 302 to the magnetic tape head assembly 216. Coarse tape guidance devices 210,222 are bi-compliant tape guidance devices which provide compliant tape edge loading on botii sides of the magnetic tape. This dual compliance allows for greater variations in tape movement. Thus, coarse tape guidance devices 210,222 provide the maximum tape guidance and control without causing tape wear or buckle of thin film magnetic tapes. This is achieved by presetting die loading on each

compliant flat spring, thereby reducing variations in applied tape edge loading and increasing the tolerance of each flat spring. This ensures accurate and reduced tape loading.

C. Fine Tape Guidance Devices

The high performance tape head system 110 of the present invention is comprised of two fine tape guidance devices 214,218. Referring to Figure 4, fine tape guidance device 214 is comprised of an air bearing 414, an upper spring assembly 440, and a fixed tape guide 420. Fine tape guidance device 214 is, therefore, a uni-compliant tape guidance device. That is, the tape edge loading which is applied to the magnetic tape as it passes air bearing

414 is compliant only on the tape edge which receives a biased loading from die upper spring assembly 440. The fixed tape guide 420 is not compliant, but rather provides a fixed surface against which the magnetic tape is positioned.

Upper spring assembly 440 is attached to air bearing 414 by upper spring assembly cover 426 and upper spring assembly cover screws 432. Dual air bearing 414 is attached to 202 platform 438 on sub-deck 202. Air bearing

414 is pneumatically coupled to a pneumatic source via pneumatic port 435 in sub-deck platform 438.

As described above, dual air bearing 410 comprises air bearing 412 and air bearing 414. Dual air bearing 410 is secured to the platform 438 via dual air bearing screws 430. The pneumatic port which supplies air bearings 412 and 414 is pneumatic port 435. Pneumatic port 435 is used to supply air pressure/vacuum to botii air bearings 412 and 414. This is because in the preferred embodiment of the high performance tape head system 110, the pneumatic pressure in the coarse tape guidance device 210 and fine tape guidance device 214 is always die same. However, as one skilled in the

relevant art would know, coarse tape guidance device 210 and fine tape guidance device 214 may be separately pressurized.

Referring to Figure 4, fixed tape guide 416 is comprised of coarse tape guidance device base plate 418 and fine tape guidance device fixed tape guide 420. As described above, coarse tape guidance device 210 is a bi-compliant tape guidance device. Therefore, coarse tape guidance device base plate 418 does not have fixed teeth which extend out from below air bearing 412 to provide a fixed reference upon which the magnetic tape is guided. Instead, coarse tape guidance device 210 provides compliant tape edge loading to die bottom edge of the magnetic tape via lower spring assembly 424.

Likewise, fine tape guidance device 218 is comprised of an air bearing 462, an upper spring assembly 472, and a fixed tape guide 468. Upper spring assembly 472 is attached to die top surface of air bearing 462 by upper spring assembly cover 478 and upper spring assembly cover screws 484. Air bearing 462 is attached to read/write sub-deck 202 platform 490 and its pressure is pneumatically reduced via pneumatic port 439.

Fixed tape guide 466 is comprised of coarse tape guidance device base plate 470 and find tape guidance device fixed tape guide 468. Base plate 470 and fixed tape guide 468 operate in a similar manner as base plate 418 and fixed tape guide 420, described above. As described above with reference to coarse tape guidance devices 210,222, die upper spring assemblies 472,440 of fine tape guidance devices 214,218 may also be assembled and calibrated according to the above-referenced patent application, "Compliant Guide Assembly for a Magnetic Tape Transport Including a Method and Fixture for Calibrating the Same."

In the preferred embodiment of the present invention, fine tape guidance devices 212,218 are uni-compliant tape guidance devices. Alternatively, fine tape guidance devices 212,218 may be pneumatically controlled tape guidance devices. Pneumatically controlled tape guidance devices are described in a commonly owned U.S. patent application, entitled

"Pneumatic Compliant Tape Guidance Device," filed on November 16, 1992, application no. 07/977,065, naming as inventor Christian A. Todd, herein incorporated by reference in its entirety.

In such an embodiment, fine tape guidance devices 212,218 would pneumatically apply a biasing load to the top of the passing magnetic tape.

The tape guidance devices would include approximately the same number of guide buttons as the fine tape guidance devices described above. However, these guide buttons are attached to pneumatically-controlled pistons which operate with pneumatic cylinders under die control of a pneumatic source. The pneumatic compliant tape guidance device also includes a pneumatic chamber for distributing die pressure/vacuum received via a supply port from a pneumatic source.

This embodiment of fine tape guidance devices 212,218 enables high performance tape path system 110 to apply a vacuum to the pneumatic tape guidance devices to retract the guide buttons from the tape path 302 during die tiireading of the magnetic tape by threading arm 106. More importantly, pneumatically controlling the guide buttons with a pressure and vacuum enables extremely accurate control over the tape edge loading. In addition, die applied tape edge loading may be changed quickly and easily by varying the pressure/vacuum. Also, the pneumatic compliant tape guidance device may be configured such diat individual guide buttons are controlled separately. This enables the tape guidance device to apply a specific customized biased loading profile along die associated air bearing.

D. Tape Guidance Device Locations

Referring to Figures 2 and 3, the fine tape guidance devices form an arcuate tape path 302 which extends from a point proximate to supply reel 102 to a point proximate to take-up reel 104. As discussed below with reference to tape transducer 234, the curvature of tape path 302 enables the high performance tape path system 110 to provide a smooth, continuous movement to the magnetic tape as it travels along tape path 302 while providing a minimum amount of air pressure to maintain tape flight between the magnetic tape and air bearings.

The length of tape path 302 provides the high performance tape path system 110 with a greater distance for guiding the magnetic tape once it leaves supply reel 102 or take-up reel 104. This distance, coupled with the greater radius of arcuate tape path 302, provides a gentler process of controlling the magnetic tape within the required tolerances. This greater control is achieved by using multiple tape guidance devices along tape path 302, each providing progressively greater control over the magnetic tape as the magnetic tape travels toward magnetic tape head assembly 216. This same arrangement is used on die machine-reel side of high performance tape path system 110. However, diere is no need for an initial tape guidance device analogous to initial tape guidance device 208. This is because take-up reel 104 is not contained in a magnetic tape cartridge having internal leader block retaining walls which may damage the magnetic tape.

Take-up reel 104 has been configured with flanges which are spaced closer together than in conventional tape path systems. This reduced flange spacing reduces staggerwrapping (the uneven wrapping of the magnetic tape around die reel). This in turn reduces die magnitude of tape movement as the tape leaves take-up reel 104.

Referring to Figures 2 and 3, fine tape guidance devices 214,218 are positioned on each side of tape head assembly 216. These fine tape guidance devices accurately guide and control the magnetic tape to prevent lateral movement of the magnetic tape as it passes magnetic tape head assembly 216. This enables the high performance tape path system 110 of the present invention to support magnetic tape heads capable of writing data to a magnetic tape having a track density of 72 data tracks per half-inch tape.

Referring to Figure 7, the distance between fine tape guidance device 414 and fine tape guidance device 462 is referred to as air bearing gap 714. Air bearing gap 714 is considerably smaller than the air bearing gap of conventional tape transport systems. Tape guide button 702 is the guide button of upper spring assembly 440 which is closest to magnetic tape head assembly 216. Likewise, guide button 704 is the guide button of upper spring assembly 472 which is closest to tape head assembly 216. Likewise, tape reference edges 706 and 708 are part of fixed tape guides 420 and 468, respectively. Thus, air bearing 414 is located behind magnetic tape 716. Likewise, air bearing 462 is located between compliant guide button 802 and reference edge 706.

As shown in Figure 7, air bearing gap 714 is the distance the magnetic tape 716 travels while not under the control of any guiding force. Thus, providing tape edge guidance at a much closer distance to the read/write head 710 reduces the unguided portion of tape path 302. This reduces the amplitude of the potential tape motion 712 which may be experienced at read/write head 710.

In die preferred embodiment, the tolerance of the magnetic tape 716 as it passes read/write head 710 is ± .00025 inches. The high performance tape path system 110 of the present invention is therefore capable of achieving

tape edge guidance error at the read/write head 710 which is less than .0005 inches. This variation in tape movement enables the high performance tape path system 110 of the present invention to support magnetic tape heads which write data to thin film high-density magnetic tapes.

V. Tape Cleaner Assemblies

Referring to Figures 1 and 2, high performance tape path system 110 of the present invention includes two tape cleaner assemblies 112,120. Referring to Figure 4, tape cleaner assembly 112 is positioned on the supply reel side of high performance tape path system 110. Tape cleaner assembly 112 is comprised of a cleaner element 452 which is attached to sub-deck platform 438. Cleaner element 452 is coupled to a pneumatic vacuum source via pneumatic port 433 in platform 438. Cleaner element 452 is positioned on a cleaner element bottom plate 456 and has a cleaner element top plate 454, all of which are secured to platform 438 via cleaner element screws 458.

Likewise, tape cleaner assembly 120, which is positioned on die take-up reel side of die high performance tape path system 200, has similar components. Tape cleaner assembly 120 is comprised of a cleaner element 498, a bottom plate 403, and a top plate 401. These components are secured to a platform 490 of sub-deck 202 via cleaner element screws 405. Cleaner element 498 is coupled to a pneumatic source via pneumatic port 437 in platform 490.

As discussed above, dual air bearings 410,460 have recesses 444,494, respectively. These recesses are designed to receive tape cleaner assemblies

212 and 220, respectively. Likewise, fixed tape guides 416,466 have recessed areas 446,496, respectively, to receive bottom plates 456,403, respectively.

Similarly, upper spring assembly covers 426,478 have recessed areas 442,492, respectively, to receive top plates 464,401, respectively.

Although tape cleaner assemblies 212,220 are located on the dual air bearing supply platforms 438,490, respectively, they are not pneumatically coupled to dual air bearings 410,460. Tape cleaner assemblies 212,220 receive a vacuum to remove debris from the magnetic tape. Conversely, dual air bearings 410,460 receive an air pressure to provide a buffer of air between air bearings 410,460 and the magnetic tape. The pneumatic distribution of die high performance tape path system 110 is discussed in detail below.

Referring again to Figures 2 and 3, the location of tape cleaner assemblies 212,220 are now discussed. Tape cleaner assemblies 212,220 are positioned as close as possible to tape head assembly 216 without sacrificing the benefits of providing guidance proximate to magnetic tape head 710. This enables the high performance tape path system 110 to provide accurate control of the magnetic tape while achieving certain benefits with tape cleaner assemblies described below. In addition, high performance tape path system 110 has two tape cleaner assemblies instead of a single cleaner assembly as found in conventional tape path systems.

Locating two cleaner assemblies as close as possible to magnetic tape head assembly 216 instead of locating one cleaner assembly at a further distance from the tape head assembly 216 increases die data diroughput of the data transport system for the following reasons. First, having a dual cleaner block arrangement enables the high performance tape path system to reduce the debris seen at the magnetic head 710 irrespective of the direction the magnetic tape is coming from. In other words, in conventional tape path systems, the magnetic tape is cleaned prior to interfacing with the read/write magnetic head only when the tape travels in a single direction. With the high performance

tape path system 110, the magnetic tape 716 is cleaned prior to interfacing with magnetic tape head 710 when the magnetic tape is traveling from the supply reel to the take-up reel, as well as when the tape is traveling from the take-up reel back to the supply reel. This increases the efficiency of the data transfer function by reducing the number of data transfer errors which require the data to be rewritten to the magnetic tape.

VI. Tape Tension Transducer

Referring to Figures 2 and 3, tape tension transducer 234 is shown coupled to coarse tape guidance device 210. Referring to Figure 3, a partial cut-away view of coarse tape guidance device 210 is provided to show die position of tape transducer 234 relative to air bearing 412. The use of a pressure transducer to determine tape tension in a tape transport system is known in the art. Typically, the magnetic tape is passed around an arcuate surface defined by an air bearing which provides a gaseous cushion between the magnetic tape and the arcuate surface. Air is typically used to create the gaseous cushion, however, any other type of gaseous material suitable for a given application may be used. Referring to Figure 4, tape tension transducer 234 is coupled to a sense port 450 to determine the pressure between the magnetic tape and the air-bearing 412 arcuate surface. Since the tape tension is directly proportional to die pressure measured at the sense port, the tension of the magnetic tape can be readily determined.

The tape tension transducer 234 of the high performance tape transport system 110 is located considerably closer to supply reel 102 than in conventional tape transport systems. This is due to the use of coarse tape guidance device 210. The bi-compliant nature of coarse tape guidance device

210 enables the high performance tape transport system 110 to establish enough control over the magnetic tape at an earlier point in tape path 302.

Tape tension transducer 234 must have a greater sensitivity to measure the lower pressure which is used to maintain tape flight in tape path system 110. As a result, conventional tape tension transducers which have amplifiers located on an interface board at some distance from the tape tension transducer are not practical. Tape tension transducer 234 has an amplifier which is integral with the tape tension transducer 234. As a result, die signal which is generated by tape tension transducer 234 is of sufficient amplitude to be transmitted to read/write pre-amplification card 204. Locating tape tension transducer 234 closer to the supply reel enables the high performance tape path system to provide quicker feedback to the tape threading mechanism to achieve gentler handling of thin film magnetic tapes during loading. This gentler handling prevents excessive tension, presently experienced in conventional tape path systems, from damaging the thin film magnetic tapes during the tape loading process.

Referring to Figure 4, tape tension transducer 234 has an electrical connector 427 which extends dirough an electrical connector aperture 431 in sub-deck 202. This enables tape tension transducer 234 to be easily replaced without removing sub-deck 202. The tape threading mechanism which utilizes the outputs of tape tension transducer 234 is described in the commonly owned U.S. Patent No. 5,219,129 to Spicer et al., entitled "Tape Threading

Mechanism," herein incorporated by reference in its entirety.

VII. Pneumatic Distribution

Referring to Figures 2 through 4, the pneumatic connections of the high performance tape transport system 110 of the present invention are illustrated. Referring to Figure 2, there are two pneumatic fittings 236,238 which are located in pneumatic fitting channels 304 and 306, respectively.

Pneumatic fittings 236,238 are comprised of top plenums 407,413 and bottom

plenums 409,415, respectively. Top plenums 407,413 are connected to bottom plenums 409,415 through sub-deck 202. O-rings 411,417 are used to provide a sealed connection between the top and bottom plenums. Pneumatic fitting 236 is used to interface high performance tape path system 110 with a vacuum source. Pneumatic fitting 238 is used to interface high performance tape path system 110 with a pressure source. Thus, only two pneumatic fittings are required to pneumatically interface the high performance tape path system 110 with tape transport system 100. In addition, locating pneumatic fittings 236,238 on the top surface of read/write sub-deck 202 provides easy access for the installation and removal of die system.

Referring to Figures 5 and 6, a bottom perspective view of high performance tape path system 110 is illustrated in an assembled and exploded view, respectively. Bottom plenum 409 is connected to cleaner assembly pneumatic tubes 502,504, which are in turn connected to cleaner assembly pneumatic fittings 602,604, respectively. These pneumatic fittings are in turn connected to pneumatic ports 433,437, respectively. Thus, top plenum 407, bottom plenum 409, cleaner assembly pneumatic tubes 502,504, and pneumatic fittings 602,604 provide a single pneumatic vacuum system to remove debris gathered by tape cleaner assemblies 212 and 220.

Bottom plenum 415 is connected to pneumatic tubes 506, 508, 510.

Tape guidance device pneumatic tube 506 provides pressure to fine tape guidance device 214 and coarse tape guidance device 210 through pneumatic fitting 606. Pneumatic fitting 606 couples pneumatic tube 506 with pneumatic tube 508, which applies pressure to initial tape guidance device 208 through pneumatic fitting 608. Pneumatic tube 510 provides air pressure to fine tape guidance device 218 and coarse tape guidance device 222 through pneumatic fitting 610. Pneumatic fittings 608,610 are coupled to pneumatic ports 435

and 460, respectively. As discussed above, pneumatic ports 435,439 are connected to dual air bearings 410,460, respectively.

Also connected to bottom plenum 415 is pneumatic tube 512. Pneumatic tube 512 provides air pressure to tape head assembly 216. The use of air pressure by the tape head assembly 216 is described below. Thus, the top plenum 413, bottom plenum 415, pneumatic tubes 506,508,510,512, and pneumatic fittings 606, 608, 610 form a complete pneumatic system which provides air pressure to all the necessary components of the high performance tape path system 110.

As shown in Figure 5, the pneumatic tubes and plenums are configured to run along the bottom of read/write sub-deck 202. Thus, having all pneumatic distribution components attached to die sub-deck 202 and not dispersed throughout tape transport system 100 enables the quick removal, installation, and maintenance of high performance tape path system 110.

V777. Magnetic Tape Head Assembly

Referring to Figures 2 and 3, magnetic tape head assembly 216 is located approximately in the center of read/write sub-deck 202 between fine tape guidance device 214 and fine tape guidance device 218. Thus, magnetic tape head assembly 216 is located approximately at the center of tape path 302. Read/write sub-deck 202 has a recessed area, referred to as die microscope access area 242, in its top surface in front of magnetic tape head assembly 216. Microscope access area 242 provides access to view the read and write gaps of the magnetic tape head 710 to verify diat tiiey are perpendicular with die tape path 302.

Magnetic tape head assembly 216 is comprised of a tape lifter valve 448 which is used to lift magnetic tape 716 away from magnetic tape head 710 when magnetic tape 716 is stopped or is being fast-forwarded or rewound from take-up reel 104 back to the supply reel 102. Tape lifter valve 448 controls the pneumatic pressure which is applied to die magnetic tape 716 through the magnetic tape head assembly 216 to control tape flight over magnetic tape head assembly 216. Tape lifter valve 448 is pneumatically coupled to the magnetic tape head assembly 216 dirough tape lifter valve pneumatic fitting 445 and lifter valve pneumatic tube 425. On the underside of tape lifter valve 448 is a pneumatic port (not shown) which couples tape head pneumatic tube 512 to tape lifter valve 448 through the read/write sub-deck 202. Tape head pneumatic tube 512 is connected to bottom plenum 415 which is in turn coupled to top plenum 413 which receives pneumatic pressure from a pneumatic source.

Referring to Figures 4 and 6, tape lifter valve 448 is controlled through electrical signals received from a transport control system (not shown). Tape lifter valve 448 has a connector 443 which is connected to cable assembly 632 through connector aperture 308. Cable assembly 632 has a tape lifter valve connector 636 which mates with tape lifter valve connector 443 through aperture 308. Connector 636 is connected to blind mating connector 514 dirough cable assembly 632. Tape lifter valve 448 controls magnetic tape head tape flight by controlling the application of pneumatic pressure received dirough pneumatic tube 512 based on electrical signals received from the tape transport control system through cable assembly 632. This accurate control of magnetic tape flight is an important feature of the present invention. Due to the above features, a magnetic tape may be rewound past magnetic head 710 at 10 meters per second (10 m/s). Contacting magnetic head 710 at this speed will cause excessive wear on the magnetic head and tape.

Magnetic tape head assembly 216 is electrically connected to read/write pre-amplification card 204 through magnetic tape head cable assembly 429. Cable assembly 429 is referred to as a flex circuit. This is because it is actually part of magnetic head assembly 216. Since flex circuit 249 is part of the magnetic head assembly 216, two 100-pin connectors which would typically be used to connect cable assembly 425 to the magnetic tape head assembly 216 have been eliminated. This reduces signal loss without interfering with the modular nature of magnetic tape head assembly 216. Cable assembly 429 extends through read/write sub-deck 204 to connect with parallel latching device connectors 628,630. Parallel latching device connectors 628,630 are used to connect cable assembly 429 with read/write pre-amplification card 204. This arrangement enables die high performance tape path system 110 to reduce the number of electrical connections which typically exist between magnetic tape head 710 and read/write pre-amplification card 204. This enables the high performance tape path system 110 to successfully transfer read signals from magnetic tape head 710 which have a low signal strength. The use of flat cable assembly 429 coupled widi the close location of read/write pre-amplification card 204 with magnetic tape head assembly 216 reduces die need for shielding the interface cables and increases the reliability of the read signals received from magnetic tape head

710.

The relative position of magnetic tape head 710 with respect to magnetic tape path 302 may be adjusted widi tape head skew adjustment screw

612, tape head skew adjustment nut 514, and tape head shims 423. The implementation and use of these elements are considered to be known to those skilled in die relevant art.

IX. Electrical Interface

The electric interfaces of the high performance tape path system 110 of the present invention are now described with reference to Figures 2, 5 and 6. First, the electrical interface between the read/write pre-amplification card 204 and die various components mounted on sub-deck 202 will be described.

Then, the electrical interface between the high performance tape path system 110 and tape transport system 100 will be described.

In the preferred embodiment of die present invention, there are three components of the high performance tape path system 110 which interface with read/write pre-amplification card 204 and tape transport 104. They are die tape tension transducer 234, magnetic tape head 710, and interface lifter valve 448. The magnetic tape head 710 is connected to pre-amplification card 204 via two connectors. These connectors are parallel latching device connector 628 and parallel latching device connector 630. Blind mating connector 514 connects tape tension transducer 234 and tape lifter valve 448 to the tape transport control system.

The physical mating of these connectors with connectors located on the read/write pre-amplification card 204 is achieved dirough die use of parallel latching device 240. Parallel latching device 240 ensures die parallel mating of connectors 628,630 and pre-amplification card 204. Referring to Figure 6, parallel latching device 240 is comprised of a guide 626 which is secured to die bottom surface of sub-deck 202. Guide 626 works in conjunction with a lock and eject catch member located on pre-amplification card 204 (not shown). Located between connectors 628,630 is a torsion bar 620 which has cams 618 coupled to each end. Torsion bar 620 is connected to connectors

628,630 via retainers 622 and retainer pins 624. Parallel latching device 240 is fully described in a commonly owned U.S. Patent No. 5,232,375, to

Christian A. Todd, entitled, "Parallel Latching Device for Connectors," issued on August 3, 1993.

Read write pre-amplification card 204 is therefore located extremely close to magnetic tape head 710. In the high performance tape path system 110, this distance is approximately 2 inches. In the conventional tape path systems described above, this distance is at least 12 inches. As described above widi reference to the magnetic tape head, the signals from die read/write tape head 710 are analog signals which are of small amplitude. As magnetic data tracks decrease in width, these signals will become fainter and more susceptible to noise and attenuation. Thus, high performance tape path system 110 can support present and future magnetic tape heads due to having die shortest possible distance between pre-amplification card 204 and tape head 710, as well as die elimination of connectors between these two components. In addition, using the parallel latching device accurately mates the tape head connectors to the read/write pre-amplifier card thus preventing errors due to misalignment or bent pins.

Referring to Figure 2, high performance tape path system 110 is coupled to tape transport system 110 via three electrical connectors. One electrical connector 242 is illustrated. The other electrical connector, which is located on the opposite side of read/write pre-amplification card 204, is obstructed from view by sub-deck 202. Thus, the electrical interface between high performance tape path system 110 and tape transport system 100 are reduced to tiiree electrical connectors.

While the invention has been particularly shown and described widi reference to preferred embodiments thereof, it will be understood by tiiόse skilled in the relevant art diat various changes in form and detail may be made dierein without departing from die spirit and scope of the invention.