Miniaturised tape cartridge drive

Abstract: A miniaturized cartridge-type tape drive for data storage applications has a main support frame (12) upon which is mounted a tape-drive motor (14) and a transducer-positioning motor (16), disposed one behind the other in generally tandom position. Both such motors preferably have generally flat silhouettes, enabling the drive to be small and compact, and both motors are directly-coupled to corresponding actuating members: a tape-driving capstan (18) for the tape-drive motor, and a rotary positioning cam (22) for the transducer-positioning motor. An elongated transducer-positioning linkage arm (40) extends from the rotary cam, to the transducer, and is pivotally mounted in mounts on the frame. The arm is biassed into contact with the cam (22) at one end, and the transducer (28) at the other by means of a spring (54).

Description: The invention relates to a magnetic tape drive, particularly of the cassette (cartridge) type. In the past, many different types of magnetic tape data memories have been devised or proposed, and at an earlier point in time such devices constituted the most widely used long-term storage medium for large quantities of data. A very frequently-encountered form of such a tape memory, used with large main-frame computers, utilizes relatively wide tape (on the order of one-half inch or 12.7 mm) which is used with large, open reels, in a reel-to-reel configuration. With the increasingly widespread development and use of smaller types of data processing and/or word processing equipment, involving "stand-alone" desk-top processor devices comparable in physical size to the input terminals used in larger computer installations, there has been an increasing emphasis on the development of smaller forms of data storage devices. Thus, a significant advent in the development of "stand-alone" terminals (described in US-A-3 760 375) utilized tape cassettes of the nature typically used in audio equipment, embodying eighth-inch (3.18 mm) tape. Following that, the "floppy" disc ("diskette") was developed and has now come into widespread use, particularly in office-type or business computer applications. Also, many developments have taken place in "hard" disc drives and memory units to make them suitable for such use, e.g., development of "Winchester"-type drives. In this increasing development, the two major underlying purposes are the need to obtain increased amounts of storage without corresponding increase in physical size, as well as the need to actually reduce the size of both the storage media and of the drive which utilizes the same. Thus, "floppy" disk media and drives have become available in sizes on the order of one-half that of the initial such devices, and the same is certainly true of "hard" disc drives, in which the media diameter has been reduced to approximately five and one-quarter inches, 133 mm (for "mini" disc drives) and to on the order of three and three-quarter inches, 95.3 mm (and indeed, in some instances, three inches, 762 mm) in more recent units (often known as "micro" disc drives). Accordingly, there is an increasing need for analogous developments in tape storage media and drives, particularly for longer-term storage, in as much as high storage capabilities may be achieved a relatively low cost by the use of tape media, and the use of tape as storage media lends itself very admirably to "backup" or "archive" storage for the disc memories used as working or operating storage during entry or processing operations. The present invention provides a miniaturized tape drive in response to the aforementioned increasing need experienced in actual practice. US 3,583,708 shows a cartridge-type tape drive having the features shown in the pre-characterising portion of claim 1. The device employs two rotary solenoids to drive the tape and position the tape head respectively. A multi-part cam assembly connects the tape head and tape head positioning motor, and extends generally vertically in the housing. The rotary solenoids and upright cam mechanism severely restrict the minimum height of the tape drive, therefore. According to the present invention there is provided a miniaturized cartridge-type tape drive having the features set out in the characterising portion of claim 1. Apparatus in accordance with the invention may, for example, be implemented in either of two known size classifications; i.e., either the now-standard "mini-floppy" package having a five and one-quarter inch (133 mm) "half-high" form factor, or the "micro-mini" package having a three and one-half inch (88.9 mm) form factor. In either case, the unit may be designed to be directly compatible with, and to use, the standard mini-floppy interface. The intended or most preferred form of tape media for use in the apparatus of the invention is the "mini-cartridge" which utilizes tape having a width of 0.150 inches (3.81 mm), for example of the type known commercially as the "DC-100" and, in a cartridge containing a 185-foot (56.4 meter) length of similar tape, apparatus in accordance with the invention will readily provide storage in excess of ten megabytes even in a formatted-type storage arrangement, i.e., of the order of from ten to twenty time the storage capacity typically encountered on one "mini-floppy" disc. Preferably the transducer-moving linkage means includes pivotally mounted arm apparatus which includes a pivot suspension mounting disposed generally between the cam means and the transducer mounting and guiding means. This mounting may comprise a pair of oppositely-disposed and mutually-spaced pivot shaft extremities, and said main frame may carry a pair of spaced journals each disposed along an opposite side of the frame, said journals rotatably receiving said spaced pivot shaft extremities thereby pivotally supporting said arm apparatus. Preferably also, the arm apparatus includes arm portions extending from the pivotal axis towards the cam means (rearwardly with respect to the main frame), the portions extending convergently towards one another and being interconnected in the area of the cam means, where the cam follower is joined to the arm apparatus. The arm apparatus may include a forwardly-projecting portion (i.e. extending from the axis towards the transducer) and being operatively, and preferably pivotally, coupled with the transducer or the transducer mounting and guiding means. A biasing member may be provided which may act to maintain operative contact between the cam means and the cam follower; the projecting portion and the transducer or transducer-mounting and guiding means; or both of them. The foregoing advantages and characteristics are obtained through the use of multiple recording tracks on the tape (e.g., eight such tracks on the type of tape indicated, approximately equivalent to track density on the order of 60 tracks per inch or 23.6 per cm), at recording densities on the order of 6,400 bits per inch (2500 per cm). Substantially enhanced performance is preferably achieved through use of "embedded servo" information recorded on the tape media, with closed-loop servo positioning of the transducer (head) in order to accurately follow (i.e., track) along the centerline of each of the multiple recording tracks on the tape, and also to accurately reposition the head at any desired track on the tape, start/stop and random access operation thus being entirely within the capabilities of the unit. Particular advantageous attributes of the apparatus in accordance with the invention include, in an overall package of exceedingly small physical size, highly reliable and yet completely flexible transducer head-positioning apparatus capable of shifting the head in small increments for accurate positioning and tracking operation and yet capable of accurate and rapid track-to-track or multiple-track head positioning operation. At the same time, highly accurate and consistent tape transport is made possible by the componentry utilized and the component-placement in the physical configuration employed. Additionally, novel and unusual head-positioning arm components and suspension provide for desirable consistency and reliability in positioning and tracking operations. The invention may be carried into practice in various ways and one specific embodiment will now be described with reference to the drawings, in which: Figure 1 is an overhead perspective view of a tape drive in accordance with the invention, the electronics circuit-board having been removed to show internal details; Figure 2 is a bottom plan view of the apparatus shown in Figure 1; Figure 3 is a fragmentary, rear perspective view showing a portion of the apparatus depicted in Figure 2; Figure 4 is a fragmentary, perspective view showing a portion of the apparatus depicted in Figure 1; Figure 5 is an enlarged, overhead plan view of the head-positioning arm assembly utilized in the apparatus of the preceding Figures; Figure 6 is a front elevational view of the positioning arm assembly shown in Figure 5; Figure 7 is a right side elevation of the apparatus shown in Figures 5 and 6; Figure 8 is a cross-sectional elevation taken through the plane VIII-VIII of Figure 5; Figure 9 is a cross-sectional elevation taken through the plane IX-IX of Figure 5; and Figure 10 is a cross-sectional elevation taken through the plane X-X of Figure 5. Referring now in more detail to the drawings, the overall tape drive, designated by the numeral 10 (Figures 1 and 2) will be seen to comprise a generally rectangular main frame 12 which peripherally encloses, and on which is mounted, the various operating components of the drive, the largest of which are a tape-driving capstan motor 14 and a head-positioning stepper motor 16. As illustrated, the capstan drive motor 14 is preferably located in the underside portion of the frame and generally centrally thereof, and mounted so that the tape-driving capstan 18, which is coupled directly to (or an integral part of) the output shaft of the drive motor 14, extends upwardly and is located in the upper portion of the frame, generally equidistant between the sides thereof and positioned directly behind the front face 20 of the drive, which defines a rectangular aperture 21 through which the tape cartridge is inserted. As will be understood, the tape cartridge is a relatively narrow rectangular object, and when inserted into the drive it is disposed generally coplanar with respect to the main frame 12 and located such that the tape drive access opening in the cartridge lies contiguous with the capstan, so that the latter may engage the tape or tape-driving wheel, within the cartridge. Upon engagement, the capstan motor is caused to pivot near or about its center of mass. Such pivoting is opposed by a spring acting against the motor, thus insuring positive engagement of the motor capstan to the driven wheel within the cartridge. The pivoting of the motor about its center of mass greatly reduces vibration. The head-positioning stepper motor 16 is mounted and positioned in a manner generally opposite that of the capstan-drive motor 14, i.e., the body of the stepper motor is disposed in the upper portion of the main frame, with the drive shaft extending downwardly into the bottom portion of the frame enclosure. Stepper motor 16 is used to rotate a head-positioning cam 22 (Figures 2 and 3) which is mounted directly on the motor output shaft and which is physically disposed in a position behind the capstan drive motor 14. The head-positioning cam 22 is preferably a rotary, single-face cam having a central hub portion 24 which receives the drive shaft of the stepper motor 16, and which has a radially-projecting helically-shaped cam face 26 preferably having approximately 300 o of rotational surface. In a particular preferred embodiment, the stepper motor 16 provides 1.8° of output shaft rotation per step, and is driven in a "half-stepping" mode, so as to yield 0.9° of rotation each half-step. The rise of the cam face 26 is preferably such as to provide, as described below, one-half mil (0.005 inches or 0.127 mm) of transducer head movement relative to the tape for each such half-step of the stepper motor. With such a configuration, the total excursion of allowable head movement is somewhat greater than the nominal total width of the tape (0.150 inches or 3.81 mm), providing for complete placement and positioning of the head at any point along the width of the tape, commencing from a position alongside the edge of the tape (i.e., not in registry with the tape). Referring to Figures 1 and 4, a transducer head 28 is fixedly mounted within a head-carrier or slide 30, and the latter is slidably mounted on a pair of cylindrical guide rods 32, 34 which pass through a set of complementary parallel passages in the head carrier 30. Preferably, the guide rods 32 and 34 depend from a retainer or mount 35 secured in place to a cross member 112 of the frame 12. With this arrangement, the head and its carrier remain in precisely-positioned orientation and location with respect to the tape path, immediately alongside the tape drive capstan 18; in this positional relationship, however, the head is shiftable across the width of the tape, as noted above. The head-positioning motion of the cam 22 is imparted to the head carrier 30 and head 28 through a pivotal control arm 40 shown in operative position in Figure 2, with individual attributes being shown in Figures 2, 3, 5, 6, 7, 8, 9 and 10. Referring more particularly to the Figures just noted, the control arm assembly 40 comprises a pivotal mounting shaft or axle 42 which is journaled in opposite sides of the main frame 12 at a point generally between the cam 22 and the head and head carrier 30, 28. Extending rearwardly from the axle 42 is a generally V-shaped (or U-shaped) follower portion 44 having a particular cross-sectional configuration to be described more fully hereinafter and carrying a cam follower 46 disposed generally at the apex of the V-shaped configuration and comprising, in effect, a projecting tab extending toward the axle 42. At the end extremity of the cam follower tab 46 is a rounded embossment or attached ball structure (cam contact) 48 which constitutes the element which actually contacts and slides along the inclined cam face 26 of cam 22. The cam contact 48 may actually be a rotatably-mounted ball bearing element if desired, but need not be a rotatable element if the cam face has at least moderately lubricious surface characteristics, as provided for example by polymeric materials such as acetal (which is preferred) or of the general nature of those materials sold under the marks "Nylon" or "Delrin". Such materials also provide for efficacious manufacture of the cam itself, through injection molding techniques. Projecting forwardly from one side of the rear portion 44 of the control arm 40 is a head-translating arm extension 50 (Figure 5), having a rounded or spherically-shaped contact element 52 which may be essentially similar to the contact element 48 at the rear portion of the control arm assembly, noted above. The forwardmost portion of the arm extension 50 projects under the transducer head carrier 30 (see Figures 3, 4 and 5), with the contact element 52 in contact with the underside of the head carrier 30 to raise the latter in accordance with downward movement imparted to the rear portion 44 of the control arm assembly 40 by the operation of cam 22 acting upon cam follower 46 through its contact member 48. Such upward head carrier motion is opposed, and returned, by an appropriate spring element 54 (Figures 1 and 4) disposed above the head carrier and mounted upon the frame cross member 112 so that a projecting end portion 55 of the spring bears downwardly against the top of the head carrier with sufficient force to overcome system friction and vibration, but with a small enough spring rate to avoid flexure of the arm. As may be seen in Figures 5, 6, 7, 9 and 10, the forwardly-projecting arm extension 50 preferably carries an upwardly-concave embossment 56, which reinforces and strengthens the arm extension and thereby avoids flexure thereof in imparting motion to the head and head carrier in the manner noted just above. In this respect, it will be observed that arm extension 50 is preferably an integral portion of the arm structure 44, extending from a side 44 b thereof as a curved projection (Figures 5, 7 and 9). This further augments the structural integrity of the overall arm assembly, and helps to avoid such flexure during head-translating actions. Such rigidity or non-flexure of the overall arm assembly is an important factor in the accurate operation of the device, bearing in mind the fact as stated above that it is desirable to accurately control head translation in movements of a half mil (0.127 mm). This performance is further enabled by providing the rear portion 44 of the control arm with a curved, somewhat channel-shaped cross section, particularly illustrated in Figure 8. In this manner, the structure of the overall arm assembly is made to be as light in weight as possible to reduce its susceptibility to vibration, and yet as rigid in performance as possible, while at the same time enabling inexpensive manufacture of the arm by way of a multiple-step stamping operation, commencing with an appropriately-configured flat, narrow strip of sheet metal. To even further augment the structural rigidity and performance of this member, and to further accommodate the severe space limitation imposed by the desired package size, the rearwardly-extending portion 44 thereof progressively narrows as it proceeds toward the cam follower portion 46, thus lending a somewhat trapezoidal configuration to the two sections 44 a and 44 b (Figure 6) and bringing their rolled or curved lower and upper edges 43 and 45 respectively, closer together in the vicinity of the cam follower projection 46. Minimization of size and weight, without reduction in strength or performance, and indeed with maximized performance characteristics, will be seen to be carried throughout the design, configuration, and structural attributes of the apparatus in accordance herewith. The numerous attributes involved in the preferred embodiment of the control arm assembly 40 will be apparent from the preceding discussion. Similar considerations will also be apparent upon considering the structural nature of the main frame 12, which as illustrated in Figures 1 and 2 is preferably a double-walled, cross-ribbed structure manufactured by injection molding of a tough, rigid polymeric material such as for example glass-filled polycarbonate. In this manner, the use of a metal casting is avoided without attendant loss of structural rigidity and dimensional stability, and with probable improvement in cost and/or weight characteristics. Other aspects also contribute significantly to the small size and compactness of the unit, as well as to its reliability and freedom from error-contributing factors. For example, even things as fundamental as the initial choice of the tape drive motor and the head-positioning motor are very important since the physical size and placement of these elements have such an important bearing on the nature and performance of other necessary structural elements. At the same time, however, such basic factors as high standards of performance, long operational life, high reliability, low cost, and of course reliable and plentiful sources of supply, are also of great importance. In this regard, the head-positioning stepper motor 16, as illustrated physically in Figure 1, is perhaps of surprising physical size in relation to the overall size of the tape drive itself, as a result of full consideration of the foregoing factors. To facilitate the very compact arrangement required by the extremely small physical size limitations imposed by the packaging requirements, as noted previously, both the drive motor 14 and the stepper motor 16 are preferably of "pancake" type, having substantially greater width (diameter) than thickness. The preferred stepper motor is a four-phase permanent magnet type which, in the size relation shown, will provide holding torque on the order of 400 grams per centimeter minimum. As previously indicated, the desired step angle is 1.8° per whole step (0.9 o per half step), with 300° of allowable motor rotation, preferably limited by an appropriate stop 27 (Figure 3) on the positioning cam 22, which is configured to come into abutting contact with one or the other side of a fixed stop 29 depending from a rear cross member 212 of the frame 12, one such position of abutment preventing movement beyond the cam position shown in Figure 3 and the other position of abutment performing a like function at the other extremity of cam rotation. As also illustrated in Figures 1 and 2, the tape-transport drive motor 14 is also of relatively large physical size for such a small tape drive unit. Preferably, this is also a relatively flat pancake-style servo motor, which may be of the type carrying stator coils on a printed circuit-board with commutation by Hall-Effect switching devices. Final drive speed, at the edge of the drive capstan 18, is such that it provides a tape speed on the order of 39 inches per second (99 cms per second), for which a nominal motor output shaft speed of the order of about 1,300 rpm is desirable. This motor should be speed-controlled by closed-loop servo techniques, and thus the motor should employ or embody an integrated tach generator, which may desirably be optical (light-chopping) in nature. As previously indicated, the cam 22 may simply be of the single-faced variety, with the cam face having a rise factor on the order of forty percent; thus, with 300° of allowable rotation, the overall length of transducer head movement provided by the cam will be on the order of 0.166 inches or 4.22 mms (thus, actually exceeding the total width of the intended tape). Also as previously indicated, both the cam and the tape drive capstan 18 are preferably direct-coupled to their respective motor output shafts, to further enhance precision control and eliminate error source. The control arm 40, in the type of "architecture" or configuration illustrated, translates the rotational movement of the cam 22 from its location near the rear of the drive to the head carrier 30 and the head 28 mounted therein, which are located at a point relatively closer to the front of the drive, spaced inwardly from the front panel 20 thereof the extent necessary to permit full insertion of the intended tape cartridge, whose width thus corresponds generally to the spacing between the capstan and the front of the main frame. To span this relatively substantial distance while precluding any significant torsion or bending effects, the control arm 40 has particular attributes of stiffness and rigidity, while at the same time preferably being extremely lightweight. Thus, the arm configuration shown in Figures 5 to 10 inclusive, while unconventional, is very desirable. In this respect, significant and preferable attributes of the arm assembly 40 include its generally pivotal nature and the location of pivot points between the cam and the transducer head, together with the various rolled and stamped shape attributes providing for the desired degree of structural rigidity already noted above. In this respect, it will be noted that the portion of the control arm disposed rearwardly of the pivot axis employs a high degree of structural reinforcement (i.e., rolled curves, bends, etc.), while the forwardly-projecting extension arm 50 includes the long embossment 56. Although the particular nature of the transducer head 28 may take a number of different forms, the head-positioning components which have been described provide for accurate, incremental control motion sufficient to position a single channel or magnetic gap at any desired position across the entire width of the tape, and preferably alongside as well, for edge-locating procedures. Such a head may employ a one channel, bi-directional read/write magnetic structure, which preferably is of a wide-write, narrow-read character. The effective track width recorded by the head should be of the order of about 0.016 inches (0.41 mm), in order to obtain track densities on the order of about 60 tpi (or 23.6 per centimetre) as indicated above. As will be understood, the overall operation of a tape drive in accordance herewith is intended to be under the overall control of a master controller constituting the user's primary processor, or operating as a function thereof. Notwithstanding this, a drive in accordance herewith is intended to include its own general operating electronics which, for purposes not particularly or directly involved in the present specification, desirably incorporates a micro-processor for such functions as servo-controlled track seek and centering utilizing embedded servo blocks recorded on the tape media, as well as a variety of other such functions. While the general attributes of such an operating system are well within the skill of the art, a more detailed description of a preferred type of control system is set forth in U.S. Patent 4,472,750, issued September 18, 1984. Preferably, the componentry which constitutes such an operating system is embodied in a PC board which may conveniently be secured atop the main frame, for example to internally-threaded stand-offs 12(a) - 12(d), inclusive (Figure 1), to in effect provide a closure therefor at the same time. Electrical connectors 60, 62 for making the necessary connections to such a circuitboard from the operative components of the drive may be nested within appropriate recesses defined by the frame 12, or otherwise secured with respect thereto. Also, the frame 12, as by its cross arm 112, may support an optical sensor block 64 for end-of-tape and beginning-of-tape sensing functions, as well as supporting cartridge-present and write-protect switches 66, 68.

Claims: A miniaturized cartridge-type tape drive comprising: a main support frame (12) defining a tape cartridge admittance opening (21); a tape drive motor (14) being mounted for support upon said frame (12); a tape-driving member (18) coupled to the output shaft of said drive motor (14) for rotation thereby and positioned in coplanar alignment with said cartridge admittance opening (21) to transport the tape in said cartridge; a transducer-positioning motor (16) mounted for support upon said frame (12); cam means (22) coupled to said transducer-positioning motor (16) to be driven thereby; transducer-moving linkage means (40) for coupling movements of said cam means (22) to a transducer (28); and transducer mounting and guiding means (30, 32, 34) adjacent said tape-driving member (18), for movably mounting said transducer (28) at said location and guiding movement of such transducer (28) transversely across the path of said tape at said tape-driving member (18), said transducer-moving linkage means (40) being operatively coupled to said transducer (28) to impart said guided movement thereto; characterized in that: the tape drive motor (14) is of flat silhouette having a height less than its width and is located behind said cartridge admittance opening (21); the transducer positioning motor (16) is of flat silhouette and is located behind said tape drive motor (14) and said cartridge admittance opening (21); and said transducer-moving linkage means (40) extends lengthwise of said frame (12) from the area of said cam means (22) to a location adjacent said tape-driving member (18). The tape drive of claim 1 wherein the tape drive motor (14) is located immediately behind said cartridge admittance opening (21); and the transducer positioning motor (16) is located behind said tape drive motor (14) with respect to said cartridge admittance opening (21) and said frame (12); A tape drive in accordance with claim 1 or claim 2 wherein the cam means (22) is directly coupled to an output shaft of the transducer-positioning motor (16). A tape drive in accordance with any one of the preceding claims wherein the cam means (22) comprises a rotary cam member. A tape drive in accordance with any one of the preceding claims wherein the transducer-moving linkage (40) includes a pivotally-mounted arm apparatus. A tape drive in accordance with claim 5 wherein the arm apparatus includes pivotal axis (42) disposed generally between the cam means (22) and the transducer (28). A tape drive in accordance with claim 5 or claim 6, wherein the arm apparatus includes are portions (44a, 44b) extending from the pivotal axis towards the cam means (22), the arm portions extending convergently toward one another and being interconnected in the area o the cam means (22). A tape drive in accordance with claim 5 or claim 6 or claim 7 wherein the arm apparatus includes a portion (5) projecting forwardly of the axis (42) towards the transducer (28), and being operatively coupled to the transducer (28) or the transducer mounting and guiding mens (30). A tape drive in accordance with any one of the preceding claims including biasing means (54) to urge either the cam means (22) and linkage means together, or the linkage means (40) and the mounting-and-guiding means (30) together, or both of these. A tape drive in accordance with any one of claims 5 and 9, wherein the arm apparatus comprises a member formed from sheet-like material and has a plurality of integral longitudinal extending portions (56) which are angularly-disposed relative to one another, for augmenting beam strength and reducing flexure of the arm apparatus during transducer-moving operation. A tape drive as claimed in any one of the preceding claims in which the drive is for data storage use and has an overall size of the same order as a half-high "mini-floppy" disc drive. A tape drive in accordance with Claim 6 wherein the pivotal axis is disposed closer to the transducer (28) than the cam means (22).

Inventors: BOLT MICHAEL LOREN, HENKE STEVEN EDWARD, IRWIN SAMUEL NELSON, LUM FRANCIS, BOLT, MICHAEL LOREN, HENKE, STEVEN EDWARD, IRWIN, SAMUEL NELSON, LUM, FRANCIS
Applicants: SEAGATE TECHNOLOGY, SEAGATE TECHNOLOGY, INC.
Application year: 1985
Main classification: G11B5
IPC codes: G11B5, G11B25