Apparatus for Loading and Unloading the Leader Block of a Tape Cartridge

The present invention relates generally to the storage of data on magnetic recording tape, and in particular, to the storage of data on magnetic tape in cartridge form.

In the course of developing various systems for the storage of data on magnetic recording tape, particularly off-line storage of data in the form of back-up storage, a variety of different formats have been developed. Many of these formats call for the tape to be contained in an appropriate cartridge, both to facilitate handling of the tape while in use, and to protect the tape while in storage.

Recently, IBM Corporation has announced a tape cartridge which is primarily intended for use in its Model 3480 data storage system, for the storage of relatively large quantities of data (on the order of 200 megabytes). Details regarding the construction of this type of tape cartridge (hereinafter referred to as a 3480 tape cartridge) may be had with reference to U.S. Pat. No. 4,452,406. By way of general description, the 3480 tape cartridge is comprised of a single reel containing a quantity of magnetic tape and contained in a rectangular enclosure having dimensions on the order of 4 inches in width, 5 inches in length, and 1 inch in height. The cartridge enclosure includes an aperture in one of its major faces, to receive means for rotating the reel of tape contained within the cartridge, and an aperture in one of its corners, for gaining access to the free end of the web of tape. A so-called "leader block" is connected to the free end of the tape, and is frictionally received within the open corner of the cartridge so that it is capable of being withdrawn from and replaced within the cartridge by appropriate means.

In connection with the 3480 tape cartridge, IBM Corporation has also developed equipment for receiving the tape cartridge and for properly placing the web of tape which it contains in operative association with a magnetic read/write head. Further details regarding such equipment may be had with reference to U.S. Pat. Nos. 4,432,508; 4,399,959; 4,399,936; and 4,335,858, which illustrate various different devices which have been developed by the IBM Corporation to accommodate its 3480 tape cartridge.

Unlike many of the other types of tape cartridges which have been developed for use in the off-line storage of data, the IBM 3480 tape cartridge houses only a single reel of magnetic recording tape. The leader block which is connected to the free end of the web of tape is used to introduce the web of tape to the transport apparatus (and the read/write head). To this end, the transport apparatus must be provided with appropriate means for withdrawing the leader block from its nesting within the 3480 tape cartridge, and for threading the leader block (and the web of tape) through the apparatus and past the read/write head. Of course, means must also be provided for unthreading the web of tape (and the leader block) from the apparatus, and for replacing the leader block within its nesting in the 3480 tape cartridge.

Accordingly, special means must be provided to engage the leader block assembly, and to guide the leader block (and the tape which follows) through the transport apparatus which is to operate upon the web of tape. This requires care in withdrawing the leader block from the tape cartridge, and in guiding the web of tape from the supply reel of the tape cartridge, past the read/write head, and into engagement with the take-up reel which is traditionally provided to cooperate with the supply reel in transporting the web of tape through the apparatus and past the read/write head. This necessitates the development of an appropriate path for threading the leader block through the apparatus, as well as means which have sufficient driving forces to withdraw the leader block from its normally seated position within the tape cartridge, and to replace the leader block within this normally seated position after the tape cartridge has been used.

To meet these needs, as well as other design requirements regarding data density and performance characteristics, those devices described in the above-identified United States patents each make use of a loading mechanism which is essentially separate from the remainder of the apparatus which is used to operate upon the magnetic recording tape. In each case, a track or groove is provided for guiding the leader block through the desired tape path and to the take-up reel, under the influence of a dedicated driving means which is separate from the various components comprising the tape transport. Although several different mechanisms are described, in each case a separate motor and track/groove drive is provided to achieve proper interfacing of the web of tape with the apparatus.

As a result of this and other design considerations, those devices which have been developed to operate upon IBM 3480 tape cartridges have generally been large, cumbersome and expensive. While this can be justified in connection with relatively large, mainframe applications, such design constraints have significantly limited, if not totally precluded use of the 3480 tape cartridge in connection with relatively low cost, minicomputer or microcomputer applications.

Yet another consideration which has inhibited use of the 3480 tape cartridge in mini/micro-computer applications is one of space. It is generally impractical, and therefore undesirable, to necessitate the purchase of an apparatus for off-line, back-up storage or the like which is significantly larger than the primary equipment which the apparatus is to support. In fact, due to the prevalent use of 51/4 inch magnetic recording (floppy) discs in connection with such applications, a de facto standard has come about for any form of storage equipment (floppy disc, hard disc, cartridge, etc.) which is to replace or relate to such conventional storage means. The recognized "form factor" or "footprint" of a standard 51/4 inch magnetic recording disc calls for a container or housing having dimensions on the order of 53/4 inches in width, 8 inches in depth and 31/4 inches in height. Those devices described in the above-identified patents are not adaptable to such applications.

Accordingly, limitations of cost and size have significantly limited the ability to use the IBM 3480 tape cartridge in mini/micro-computer applications.

It is therefore a primary object of the present invention to provide an apparatus for receiving and operating upon an IBM 3480 tape cartridge, which is sufficiently compact to fit within a standard 51/4 inch footprint or form factor.

It is also an object of the present invention to provide such an apparatus with means for engaging the leader block of the tape cartridge, for loading and unloading of the magnetic recording tape which it contains, without compromising performance of the tape cartridge.

It is also an object of the present invention to provide such means in an apparatus which is simple and reliable in operation, and which is cost effective even in connection with mini/micro-computer applications.

These and other objects are achieved according to the present invention by providing a simplified means for loading and unloading the leader block of a 3480 tape cartridge, making use of a loading/unloading mechanism which is directly associated with the take-up reel of the apparatus rather than a separate mechanism. To this end, the take-up reel of the apparatus is provided with a linkage which extends from the periphery of the take-up reel, and which has a pin for engaging the leader block of the tape cartridge. The pin of the linkage is caused to proceed along a specified path, following a camming surface under the influence of an over-center spring, to achieve effective transfer of the leader block from the tape cartridge, through its specified tape path, to the take-up reel, and vice versa. Consequently, leader block loading and unloading is accomplished without requiring the use of an additional drive mechanism for this purpose, significantly reducing the number of components of the apparatus, and enabling the apparatus to be reduced to a size which can be fit within a standard 51/4 inch footprint or form factor.

For further detail regarding a leader block loading mechanism in accordance with the present invention, reference is made to the following detailed description, taken in conjunction with the following illustrations.

FIG. 1 is a top plan view of an apparatus for loading and unloading the leader block of a tape cartridge in accordance with the present invention, showing the tape cartridge as it is initially received within the apparatus.

FIG. 2 is partially sectioned, side elevational view of the apparatus shown in FIG. 1.

FIGS. 3 to 5 are top plan views similar to FIG. 1, showing sequential operation of the leader block loading mechanism.

FIGS. 6 and 7 are top plan views similar to FIG. 1, showing operation of the apparatus as the leader block is unloaded.

In the several views provided, like reference numerals denote similar structure.

Although specific forms of the invention have been selected for illustration in the drawings, and the following description is drawn in specific terms for the purpose of describing these forms of the invention, this description is not intended to limit the scope of the invention which is defined in the appended claims.

FIGS. 1 and 2 show a transport apparatus 1 for receiving and operating upon an IBM 3480 tape cartridge 2 in accordance with the present invention. To be noted is that the apparatus 1 is sufficiently compact to be received within the confines of a standard 51/4 inch form factor or footprint.

The tape cartridge 2 generally comprises a quantity of tape 5 wound upon a supply reel 6 and contained within a housing 7. Suitable means (preferably a geared, magnetic coupling) are provided for placing the supply reel 6 in operative association with a supply motor 3 positioned beneath the surface 8 of the transport apparatus 1. A corner 9 of the housing 7 is open, and receives a leader block 10, which is used to securely engage the free end 11 of the web of tape 5 in the manner shown.

After being received within the transport apparatus 1, the tape cartridge 2 is then readied for further operation as follows. First, the supply reel 6 is operatively connected to the supply motor 3 which is positioned beneath the surface 8 of the transport apparatus 1, so as to achieve desired rotation of the supply reel 6 in accordance with the selected mode of operation of the transport apparatus 1. Second, a configured pin 15 is brought into engagement with the slot 12 (and counterbore 12a) which is conventionally provided in the leader block 10 of the tape cartridge 2, so as to operatively connect the leader block 10 with the leader block loading/unloading mechanism 20, and ready the leader block 10 for loading into the transport apparatus 1 as will be described more fully below. Such operative connections may be developed in any of a number of ways, such as by lowering the tape cartridge 2 from a standby position in alignment above the geared, magnetic coupling and configured pin, to an operative position for engaging such components.

The leader block loading/unloading mechanism 20 is generally comprised of three major components including a configured take-up reel 21, a contoured camming surface 22, and an engagement mechanism 23.

The take-up reel 21 is operatively connected to a take-up motor 19 by a concentric hub 24 and coupling 25. The hub 24 is attached to the take-up motor 19, and includes a cylindrical wall 24a which serves to receive the web of tape 5. The coupling 25 is nested within the hub 24, and is operatively connected to the hub 24 by a pair of pegs 27 which depend from the coupling 25 and into a concentrically arranged pair of slots 26 formed in the hub 24.

The coupling 25 is additionally provided with a cavity 28 which is correspondingly configured to the leader block 10 of the tape cartridge 2, and the wall of the hub 24 is provided with a corresponding slot 32 which permits communication with the cavity 28 of the coupling 25 upon proper alignment of the hub 24 and coupling 25 as will beoome apparent from the description which follows. The cavity 28 is preferably configured to securely receive the leader block 10 so that the rear face 29 of the leader block 10 fills the slot 32 and co-terminates with the periphery of the hub 24, essentially completing the periphery of the hub 24 so as to properly receive the web of tape 5. The upper surface 30 of the coupling 25 is provided with a flange 31 which, as a secondary function serves to retain the web of tape 5 to the take-up reel 21, and as a primary function serves to receive the engagement mechanism 23, at the pivot 35.

The engagement mechanism 23 is generally comprised of an arm 36 which extends from the pivot 35 to the pin 15 which is used to engage the slot 12 of the leader block 10, and a spring 40 which is connected between an attachment point 41 fixed on the arm 36 and an attachment point 42 fixed on the flange 31. For reasons which will become apparent from the following description, the spring 40 is pivotally connected between the flange 31 and the arm 36 so that the spring 40 is caused to proceed through an "over-center" position wherein in certain orientations, compression of the spring 40 will cause a clockwise rotation of the arm 36 about the pivot 35, while in other orientations, compression of the spring will cause a counter-clockwise rotation of the arm 36 about the pivot 35. Such rotation is responsive to the position of the pivot 35 with respect to the line of forces developed between the attachment points 41, 42.

The contoured camming surface 22 is positioned above the flange 31 of the take-up reel 21 so that the take-up reel 21 and the engagement mechanism 23 are capable of movement beneath the contoured camming surface 22, but so that the upper end 43 of the pin 15 is capable of following the face 44 of the contoured camming surface 22 to achieve loading and unloading of the leader block 10 as follows.

FIGS. 3-5 show sequential operation of the loading/unloading mechanism 20 of the present invention to transfer the leader block 10 of the tape cartridge 2 from its seated position within the corner 9 of the housing 7, past a read/write head 45, and to the cavity 28 formed in the take-up reel 21, so that the web of tape 5 is ready for transport between the supply reel 6 and the take-up reel 21 under the influence of the motors 3, 19.

To accomplish this, the take-up reel 21 is caused to undergo a counter-clockwise movement under the influence of the take-up motor 19. In the course of initiating such movement, the slots 26 of the hub 24 are caused to proceed through a defined angle until such time as the pegs 27 engage the ends 46 of the slots 26, directly coupling the motor 19 to the coupling 25. The stored kinetic energy resulting from such movement has been found to be sufficient to cause a retraction of the engagement mechanism 23 which is sufficient to snap the leader block 10 from its nesting within the housing 7. Further detail regarding this "snapping" action may be had with reference to a co-filed and commonly owned United States patent application Ser. No. 842,487 filed Mar. 21, 1986 in the name of Jay Smith and entitled "Apparatus for Coupling a Drive Motor to a Leader Block Loading/Unloading Mechanism", the subject matter of which is incorporated by reference as if fully set forth herein.

Further retraction of the engagement mechanism 23 responsive to continued counter-clockwise rotation of the take-up reel 21 causes the pin 15 (with the leader block 10 attached) to progress to the left as shown in FIG. 3, bringing the upper end 43 of the pin 15 into engagement with the face 44 of the contoured camming surface 22. At this point, the spring 40 serves to urge the pin 15 toward the face 44 of the contoured camming surface 22 as the pin 15 progresses along the defined contour.

Further counter-clockwise rotation of the take-up reel 21 serves to guide the leader block 10 through the transport apparatus 1 for delivery to the take-up reel 21. As a result of this motion, the web of tape 5 is caused to progress around an idler roller 47 and past a pair of bearings 48 disposed on opposite sides of the read/write head 45 to develop an appropriate tape wrap at this interface.

With reference to FIG. 4, the leader block 10 is eventually drawn inwardly along the segment 49 of the camming surface 22, toward the cavity 28 of the take-up reel 21. Further counter-clockwise rotation of the take-up reel 21 causes the leader block 10 to enter the cavity 28. To enable the leader block 10 to enter the cavity 28, two considerations arise. First, the leader block 10 must arrive in general alignment with the cavity 28 as the take-up reel 21 is rotated. Such dynamic placement of the leader block 10 is accommodated by the configuration of the engagement mechanism 23. Second, the slot 32 in the hub 24 must be aligned with the cavity 28 in the coupling 25 for the leader block to enter the cavity 28. This is accomplished by properly placing the slot 32 in relation to the slots 26 of the hub 24, so that the slot 32 and the cavity 28 are brought in alignment when the pegs 27 contact the ends 46 of the slots 26 as previously described.

As the leader block 10 enters the cavity 28, the line of forces of the over-center spring 40 as defined by the attachment points 41, 42 crosses the pivot 35. As a consequence of this, the spring 40 now serves to urge the leader block 10 inwardly toward the center of the take-up reel 21, assuring that the leader block 10 becomes fully and firmly seated within the cavity 28, as shown in FIG. 5. As a result, the periphery of the hub 24 becomes completed by the surface 29 of the leader block 10, permitting the web of tape 5 to be wound around the take-up reel 21 for subsequent transport between the supply reel 6 and the take-up reel 21 in otherwise conventional fashion. To be noted is that this results in a positive engagement of the web of tape 5 by a hub 24 which is rigidly coupled to the take-up motor 21, so as to assure that the web of tape 5 is properly transported in accordance with generally recognized principles.

Of course, the web of tape 5 must be transported between the supply reel 6 and the take-up reel 21 in a manner which assures that the web of tape 5 is in proper contact with the read/write head 45. In delivering the leader block 10 to the take-up reel 21 as previously described, this is automatically assured by proper placement of the bearings 48 with respect to the read/write head 45.

Having properly threaded the web of tape 5 through the transport apparatus 1, and having placed the web of tape 5 in appropriate contact with the read/write head 45, desired transfers of data may then take place in otherwise conventional manner. This proceeds until such time as the transfer of data has been completed and the tape cartridge 2 is to be unloaded from the transport apparatus 1. In essence, this is acoomplished by reversing the above described steps. However, there are certain differences which should be noted in this regard.

The first step necessary is to rotate the supply motor 3 in a clockwise direction until such time as the web of tape 5 is fully unwound from the take-up reel 21. At this point, the forces developed by the spring 40 will still be such as to urge the leader block 10 toward the center of the take-up reel 21. These forces are overcome by placing an appropriate tension on the web of tape 5 under the influence of the supply motor 3. With reference to FIG. 6, this serves to pull the leader block 10 from the cavity 28 of the take-up reel 21, until such time as the line of forces again crosses the pivot 35. As a result the forces developed by the spring 40 will then be such as to direct the leader block 10 generally outwardly, so as to again bring the upper end 43 of the pin 15 into contact with the segment 49 of the camming surface 22.

Continued clockwise rotation of the supply motor 3 causes the pin 15, and the leader block 10, to progress along the face 44 of the camming surface 22, until such time as the web of tape 5 and the end 29 of the leader block 10 are returned to the housing 7 of the tape cartridge 2, and the end of the leader block 10 which is engaged by the pin 15 is in a position just outside of its nesting in the corner 9 of the tape cartridge 2, with reference to FIG. 7. A guide 50 is preferably provided to assist the leader block 10 in clearing the idler roller 47, just prior to entering the tape cartridge 2.

Further action upon the reels 6, 21 is needed to force the leader block 10 into its nesting in the corner 9 of the tape cartridge 2. The energy required to fully snap the leader block 10 into the housing 7 is again primarily supplied by the hub 24 which connects the take-up reel 21 to the drive motor 19. As previously described in referencing the co-filed U.S. patent application of Jay Smith, entitled "Apparatus for Coupling a Drive Motor to a Leader Block Loading/Unloading Mechanism", the kinetic energy needed to return the leader block 10 to its nesting is again capable of being developed as a result of respective slippage between the slots 26 of the hub 24 and the pegs 27 of the coupling 25. After such steps have been taken to seat the leader block 10 in the housing 7, the take-up reel 21 may be retracted slightly, if desired, to test the seating of the leader block 10 and make sure that it has been fully snapped back into the housing 7.

It will therefore be seen that the foregoing apparatus serves well to satisfy each of the objectives previously set forth. The means used to load and unload the leader block 10 are directly associated with the take-up reel 21, as distinguished from a fully independent threading/unthreading mechanism. The movements necessary for proper operation of the apparatus are developed by properly configuring the flange 31 and the arm 36 of the engagement mechanism 23, in combination with the storage of energy provided as a result of interaction between the hub 24 and coupling 25 of the take-up reel 21. Moreover, these benefits are achieved within the confines of a transport apparatus 1 which is capable of fitting within the standard 51/4 inch form factor or footprint which is preferred in connection with mini/micro-computer equipment.

It is to be understood that the foregoing apparatus is capable of variation without departing from the spirit and scope of the present invention. For example, the read/write head 45 and the bearings 48 are capable of being moved to different locations along the surface 8 of the transport apparatus 1, and with respect to one another. Also capable of variation is the contour of the camming surface 22. It is also possible for different engagement mechanisms 23 to be developed by varying the configuration of the arm 36, or by varying the configuration of the take-up reel 21. The spring 40 is also capable of variation, so long as an appropriate over-center configuration is selected. If desired, the spring 40 can even be replaced with equivalent structures such as a double-sided cam, for example. Additionally, although use of the interactive hub 24 and coupling 25 as previously described is preferred, to reduce the size and current requirements for the take-up motor 19, it is also possible to eliminate such structures in favor of a rigid coupling, if desired, provided an appropriate take-up motor 19 is used.

It will therefore be understood that various changes in the details, materials and arrangement of parts which have been herein described and illustrated in order to explain the nature of this invention may be made by those skilled in the art within the principle and scope of the invention as expressed in the following claims.