CA1078750A - On-line tape library system - Google Patents

Abstract

Abstract of the Disclosure An on-line magnetic tape library system has a common transfer mechanism capable of advancement along a center aisle between rows of tape reels stored in one or more tape modules arranged in end-to-end relation. The transfer mechanism undergoes high-speed movement under the control of an operating program to different select-ed positions along the tape modules and includes a selec-tor mechanism capable of selective removal of a tape from a storage position for transfer to and from an automated reel mount unit for a tape transport in such a way that several tapes may be processed at one time.

Description

.
r ` The system of the present invention is intended in the specific embodiment described to incorporate the storage cell disclosed in United States Patent 3,868,018 entitled TAPE
REEL CARTRIDGE STORAGE CELL, and the apparatus disclosed in ~: :
United States Patent 3,920,195 entitled AUTOMATIC TAPE REEL ' MOUNT, both patents assigned to the same assignee as is the , present application.
¦ This invention relates to a novel and improved method and apparatus for storage and random retrieval of information, such as, information stored on magnetic tape reels;
and more particularly relates to a method and apparatus adapted for use with computers and the like for automated transfer of tape reel cartridges stored in preselected positions to and from one or more tape transport mechanisms in processing information on the tape.
It has been proposed to employ automated tape library systems for storage and handling of magnetic tape reels wherein a plurality of tape reel cartridges are stored in pre-selected positions and a transfer mechanism is utilized under the control of a computer to locate a given cartridge, remove it from its storage position and advance it to a tape transport ; where the tape cartridge is mounted on a drive spindle and information on the tape is processed. More sophisticated systems presently in use, commonly referred to as on-line tape library systems, permit storage and automatic retrieval of information on tape reels which are contained in self-threading tape cartridges, such as, a cartridge of the type disclosed .... , ~

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in United States Letters Patent to Fitzgerald et al No.
3,620,478, assigned to International Business Machines Corporation. Utilization of this type of tape cartridge avoids the time-consuming operation o~ removal of the tape reel from the cartridge for placement on the drive spindle of a tape transport mechanism, since in the self-threading cartridge, the cartridge can be loaded on ~, .
the drive spindle and information on the tape can be processed internally of the cartridge. At the same time, the self-threading tape reel cartridge is relatively large and bulky and, in the past, the handling has pre-sented a number of problems and difficulties associated both with respect to storage and handling of the tape as well as accurate positioning and alignment of the cartridge on the tape transport unit by the handling mechanism.
Moreover, now that commercially available tape transport units are capable of processing tape at high rates of speed it has become extremely important to provide a system capable of handling and transfering the cartridges to and from the tape transport units in the least possible time while affording maximum storage capacity for the greatest number of tape cartridges.
Accordingly, among the more important require-ments of automated tape library systems are maximum stor-age capacity, safe, dependable handling of the tape cartridges, particularly in transfer of the tape reels or cartridges to and from a storage position and the tape transport unit where the information is to be pro-cessed on the tape, and close coordination between the ,:

handling of the tape on the tape transport and advancement ofthe same or other tapes between the tape transport and the storage positions in the library.
In United States Patent 3,920,195 for AUTOMATIC
TAPE REEL MOUNT, there is disclosed apparatus for automatically advancing a tape reel from a pre-load station internally of the tape library to the drive spindle of a tape transport externally of the library; and after processing the tape, returning the tape to a post-load position internally of the library. The apparatus as disclosed can be controlled by an operating program from a computer and the like in close coordination with an automated transfer or selector/positioning mechanism for advancing the tapes between their respective storage positions and the tape transport. In order to achieve maximum storage capacity coupled with safe, rapid handling of the tape cartridges, it is desirable that the selector/
positioning mechanism operate independently of but in close coordination with the automatic tape reel mount and in such a way that the tape cartridges can be stored in rows or banks parallel to the tape reel mount along opposite sides of a center aisle, and the selector/positioning mechanism can be advanced along the center aisle under the control of an operating program to a given storage position where the tape cartridge is removed and thereafter advanced in a minimum of time to the pre-load position on the tape reel mount; or the tape cartridge can be ! removed by the selector/positioning mechanism either from the pre-load or a separate post-load station and returned in a minimum of time to its -`` 1(:~78~50 `....... ; :

original storage position. Accordingly, the selector/
positioning mechanism can be free to operate independent-ly of the tape transport in retrieving cartridges from storage for placement at a pre-load station for the tape transport or to return cartridges to storage as other cartridges are being advanced to or from the tape trans-port itself. Moreover, a common selector/positioning mechanism is capable of advancement along one or more modules of tape storage cells arranged in end-to-end r~lation to one another with selected modules pro-vided with separate tape transport and associated load-ing stations. A system of the type described places particularly severe demands and requirements upon the selector/positioning mechanism and its ability to handle a maximum number of tape cartridges in a safe, dependable manner and in close coordination with the handling of the tape cartridges at the tape transport station.
Accordingly, it is an object of the present ;~ invention to provide for a novel and improved tape stor-age and processing apparatus in which tape reels in stor-age may be automatically located and transferred between their respective storage positions and one or more tape transport mechanisms.
It is another object of the present invention ; to provide in a recorded tape library system for an auto-mated tape transfer mechanism which is capable of advance-ment to a tape storage location, engaging a selected tape and advancing it to a tape transport mechanism and vice versa in a minimum amount of time while providing for safe dependable handling of the tape.

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~' It is a further object of the present invention to provide for compact storage of recorded tapes in rows along opposite sides of a transfer mechanism to an on-line tape library system and wherein the transfer mechanism therefor is capable of selection and removal of a given tape in a dependable manner without danger of damaging the tape or its container.
It is a further object of the present invention to provide for a modular recording tape library system which can be readily modified to suit the needs of the user and in such a way that a common transfer mechanism is capable of advancing to one or more modules contain-ing tape storage cells along opposite sides of the modules, the tape transfer mechanism being operable in close opera-tion with a tape transport mechanism under an operating program from a computer and the like.
It is an additional object of the present in-vention to provide for a tape transfer mechanism which is ca~able of constant acceleration and deceleration between any two different points in a recording tape library system under operating command from a computer and the ; like in further cooperation with a positioning unit includ-ing a vacuum chuck for selective engagement and removal of tape reels or cartridges.
In accordance with the present invention, a modular recording tape library system contains rows of tape storage cells arranged along opposite sides of an elongated horizontal guide track, or center aisle, which is traversed by a unique form of selector/positioning or transfer mechanism. The transfer mechanism includes a self-propelled carriage movable horizontally of the 1(37~750 guide track, and the tape reel selector means is mounted for movement vertically of the carriage, the seIector means including a vacuum chuck movable in a horizontal direction transversely of the guide track into and away from engagement with a selected tape reel.
In accordance with the invention there is provided in an automated tape library system wherein record tape con-tainers are mounted in rows of storage cells along opposite sides of an elongated horizontal guide track, the combination therewith of: self-propelled carriage means including a vertical post mounted for horizontal movement along said guide track; tape container selector means mounted for movement vertically of said self-propelled carriage means, said tape container selector means including tape container engaging means movable in a horizontal direction transversely of said horizontal guide track; horizontal drive means for advancing said self-propelled carriage means along said horizontal guide track; vertical drive means for advancing said tape container selector means vertically of said self-propelled carriage 20 ~ means to a position alignment W~h a tape conta~er ~ be removed;
selector drive means for advancing said tape container engaging means toward and away from a storage cell for selected replacement or removal of a tape container; and rotational drive means for rotating said tape container engaging means about said vertical post between opposite sides of said rows of storage cells.
In a preferred embodiment of the present invention, the selector means and vacuum chuck are specifically designed for use in association with tape reels stored in self-threading tape cartridges which are stored in upright storage cells ~_ - ~ ~ 1078750 arranged in rows along opposite sides of the guide track. The ~-library system is comprised of storage ceIl modules wherein a ;~
plurality of modules can be arranged in end-to-end relation to one another and a common horizontal guide track extended through the modules for advancement of the carriage and associated selector means. One or more of the modules includes a tape transport mechanism provided with pre-load and post-load stations located internally of the library, the loading stations aligned in parallel with the storage cells and the tape selector means is capable of advancement to a position aligned with a given storage cell location and the selector means being rotatable about the carriage for advancement of the vacuum chuck horizontally into engagement with the peripheral edge of the tape cartridge.
`' The vacuum chuck will effect sealed engagement with the peripheral edge of the tape cartridge and, under negative pressure, will cause the tape cartridge to be removed ; from its storage location when the chuck is retracted horizontally away from the storage cell location. The tape cartridge removed is then advanced along the guide ~:

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~78'^~0 track to a point aligned with the pre-load station of the tape transport mechanism and advanced by the vacuum chuck into a receptacle provided for the tape on the pre-load station, following which the negative pressure is re-moved and the tape cartridge released at that station.
The selector/positioning mechanism is then available for use independently of handling of the tape cartridge by the tape transport mechanism either for advancement to another storage cell location for retrieval of another tape cartridge or for advancement to the post-load station on the tape transport assembly to recover a tape follow-ing processing for return to its original storage loca-tion.
A unique combination of transducer or sensing strips are provided for use in cooperation with an operat~
ing program in a computer and the like to control horizon-tal and vertical movement of the selector/positioning mechanism between different given points along one or ` more of the modules including a speed control system to control acceleration and deceleration of the mechanism between its start point and end point over a given dis-tance interval as well as to accurately center the mechanism with respect to a desired end point.
The above and other objects, advantages and features of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of a preferred form of invention when taken together with the accompany-ing drawings, in which:
Figure 1 is a perspective view with portions broken away of a preferred form of modular tape library system in accordance with the present invention.

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Figure 2 is a front view in elevation of the preferred form of selector/positioning mechanism for handling and transfer of tape cartridges in the library system.
Figure 3 is a cross-sectional view taken about lines 3-3 of Figure 2.
Figure 4 is a perspective view of a preferred form of tape cartridge selector assembly mounted on the selector/positioning mechanism.
Figure 5 is a cross-sectional view taken about lines 5-5 of Figure 2.
Figure 6 is a cross-sectional view taken about lines 6-6 of Figure 2.
Figure 7 is a sectional view taken about lines 7-7 of Figure 6.
Figure 8 is an enlarged front view of the front face of the vacuum chuck for the selector mechanism.
Figure 9 is a somewhat diagrammatic view of ; the module address sensing strip in accordance with the present invention.
Figure 10 is a diagrammatic view of the cell location sensing strip.
Figure 11 is a diagrammatic view of the verti-cal position sensing strip; and Figure 11 is an enlarged view in detail of a portion of the timing track of the sensing strip shown in Figure 10.
Figure 12 is a diagrammatic view of the sensing strip for translational movement of the cartridge selector -assembly.
Figure 13 is a diagrammatic view of a portion of the sensing strip for sensing rotational movement of the selector mechanism; and Figure 14 is a somewhat schematic view of the speed and position control circuit for the preferred form of library system.
Referring in detail to the drawings, a prefer-red form of on line automated tape library system L is illustrated in Figure 1. As shown in Figure l, the prefer-ed form of on-line automated tape library system L is illustrated in Figure l. As shown in Figure l, the pre-ferred form of library system L is illustrated from one end with portions of the outer walls or closure removed to illustrated disposition of rows of tape cartridges T
arranged in upstanding, side-by-side relation to one another in storage cells represented at C along opposite sides a series of storage modules M disposed in end-to-end relation to one another. A library control module M' is located intermediately of the storage module M
and has reel entry and exit doors El and E2 for insertion and removal of tape cartridges T. The control module Ml contains all of the necessary electronics for driving the electromechanical units of the system including the power supplies and electronic interface between the system and the selector channel of a conventional computer, such as the IBM System 360 and 370 through a standard I/O interface connection.
A selector/positioning or transfer mechanism represented at S advances along the center aisle of the entire system on an elongated horizontal guide track in the form of a drive rail R extending between the rows of tape cartridges T. The mechanism L includes a cartridge selector or picker mechanism B which is automatically controlled to move vertically and horizontally toward and away from the tape cartridges~ As will be hereinafter `` 1~7fl~7~0 described in more detail, the mechanism B also can be rotated about its vertical mounting post V when necessary to advance a tape cartridge from one side in loading or unloading onto and from the automatic reel mount unit A.
In the form of tape library module shown, the un-it A includes a tape transport D mounted externally of the module and directly outside of a passageway or opening P
through one side of the module with its drive spindle or hub H on an axis parallel to the axes of the tape cartridges T mounted in the module M. Passageway P af-fords access between the interior of the module and the tape transport in passing a selected tape cartridge through the passageway into engagement with the tape transport under the control of the reel mount assembly A. In processing information on the given tape reel, the reel mount unit A is disposed in the passageway P
between the tape transport D on the exterior of the module and a pre-load station N and a post-load station O located on the inner wall of the module adjacent to ; 20 the side edge of the passageway directly opposite to the tape transport and facing in the same direction. As illustrated, the pre-load station N is located directly above the post-load station O, and the stations N and O
are correspondingly formed of shallow, circular recept-acles 5 and 6, respectively, on a common, generally rectang-ular support affixed to the side wall of the module M
along a vertical edge of the passageway and facing in a direction normal to the passageway. For the purpose of describing the present invention, a representative form of tape cartridge T may be of the self~threading type in which an outer circular rim 9 encases the outer edge of .
,. i , ~07B~50 a magnetic tape reel and employs a vacuum threading sys-tem in the tape transport to selectively remove the lead-ing edge of the tape in processing information on the tape. For instance, the tape cartridge may be of the type disclosed in United States ~etters Patent to Fitzgerald et al No. 3,620,478 assigned to International Business Machines Corporation. There, the rim 9 is of generally U-shaped cross-sectional configuration having opposite sides overlapping the reel and joined together by an outer circumferential edge surface 9' and locating ribs on the edge are adapted to be aligned with keyways on the tape drive hub H.
The advantages and features of the tape library system of the present invention can be best appreciated from a consideration of the closely coordinated sequence of operations performed by the selector/positioning mech-anism S in cooperation with the tape reel mount unit A.
The selector/positioning mechanism S is advanced along the rail R under the control of an operating program from the central control module M' until the picker mechanism B is aligned opposite to a desired tape cartridge. The picker mechanism is advanced by a separate control or drive signal into engagement with the desired cartridge to re-move it from its cell and retract it to a center position.
The selector/positioning mechanism S is then moved along the rail to a position opposite to the pre-load and post-load stations N and O where the tape cartridge is aligned with the pre-load station N. If necessary, the picker mech-anism B may be rotated about the post D and advanced hori-zontally to move the cartridge into position at the pre-load station, at which point the tape cartridge is select-ively released by the picker mechanism in the receptacle.

14~78750 The picker mechanism is thereafter retracted away from the pre-load station, and the automatic reel mount unit A, in-dependently of the selector/positioning mechanism, transfers the tape cartridge from the pre-load station N to the tape transport D. After the information is processed on the tape by the tape transport, the reel mount assembly A is activated to remove the tape cartridge and return it through the passageway P into registration with the post-load station O. The mechanism S is then operative to advance the picker mechanism into engagement with the tape cartridge at the post-load station O and return it to its original storage position within the module M, all of this being accomplished under the control of the operating program from the control module M' in a manner to be hereinafter described. In the preferred form of invention, each storage module M contains five rows or levels of tape cartridges on each side of its center aisle, each row comprised of twenty-two cells C for reception of a corresponding number of tape cartridges.
Additionally, a space equivalent to approximately twenty : cell positions is used for disposition of an automatic reel mount unit A and its pre-load and poæt-load stations as described which are respectively disposed in horizon-tal alignment with the third and fourth levels of the tape cartridge cells. Accordingly, the selector/positioning mechanism S must be capable of traversing the entire length of the module system in a horizontal or "X" direction, advancing vertically between the different rows, or in a "Y" direction, advancing traversely of the length of the 30 modules toward and away from the cartridge cells as well ..
as the pre-load and post-load stations, or in a "Z" direc-tion; and of rotating through 180 for alignment with ~: - 12 -.

i ~)7875() cell positions on opposite sides of the module or in a "0" direction. Moreover, in advancing between the various cell positions and the reel mount stations, under command from a computer and the like the carriage must be accur-ately centered with respect to the cell postiion and reel mount stations for accurate loading and unloading of the tape cartridges. In accomplishing the foregoing, and specifically referring to Figures 2 and 3, the mechanism S includes the vertical post V mounted on a platform 10, the vertical motion carriage 12 disposed on the vertical post V and the picker mechanism B for engaging the tape cartridge and advancing between the cell positions and reel mount stations. The selector/positioning mechanism S is guided for advancement in the horizontal or "X" dir-ection along the rail R by front and rear pairs of upper and lower guide rollers 13 and 14, respectively, journal-ed on the platform 10. A horizontal drive motor 16 is mounted on the platform 10 and includes a downwardly projecting drive shaft, not shown, upon which is mounted a pinion 15 for engagement with a rack 20 formed along the entire length of one side face or flange of the guide rail R. In addition, an incremental encoder represented at 22 is keyed to the drive shaft of the motor 16 so as to be rotated by the drive shaft and to generate a ser-ies of pulses for the purpose of measuring the distance of advancement of the mechanism S along the rail R. The various power supply and logic lines into the selector/
positioning mechanism S from the library control unit are carried through a flexible belt 23 which is clamped at one end 24 to lateral extension 25 of the platform 10.
As shown, the flexible belt suitably extends over a pulley ~7E~S~

supported by a spring-loaded cable, not shown, so as to be capable of extension and retraction of the flexible belt 23 as it follows movement of the mechanism S through-out the length of the system. Although not illustrated in detail, certain of the connections from the flexible belt 23 extend to the drive motor 16 and encoder 22, while others extend upwardly through an extension 23' of the flexible belt 23 along a vertical channel 27. A
guide pulley 28 is slidable vertically of the channel, 'i3 10 and the extension 23~ is trained around the pulley and ,.~
attached to the vertical motion carriage 12 to feed the necessary power supply and logic lines into that carriage as well as the picker mechanism B. The channel 27 ex-tends approximately half-way up the vertical distance of .~ movement of the carriage 12 in guiding movement of the pulley over that distance in controlling extension and re-- traction of the belt extension 23'.
`~ In order to sense the distance and speed of movement of the entire mechanism along the rail R, a 20 series of upright transducer sensing strips 29, 30 and 31 are mounted on a common frame 32 for horizontal extension along the entire length of the library system. Outboard extension 34 of the main platform 10 carries a series of sensing means in the form of downwardly projecting transduc-er arm or block assemblies 29' and 30' which straddle the inboard and outboard strips 29 and 30; and also carries a pair of front and back transducer blocks 31' and 31"
which straddle the outer extreme strip 31. Each of the transducer arms includes a bank of light-emitting diodes 33 passing along one side of each transducer strip and a ,l~t7f~5~

bank of phototransistors 35 passing along the opposite side of the transducer strip; and each transducer strip presents alternate light and dark areas defining sensing members which selectively pass or interrupt the light beam from the light-emitting diodes in order to sense the location of the mechanism both with respect to each mod-~ ule and with respect to cell positions within each module.
; For this purpose, the inboard strip 29 is formed with al-ternate light and dark areas aligned with the cell posi-tions along the opposite or "front" side of the modules ; from the transducer strip 29, the outboard strip 30 pre-sents alternate light and dark areas aligned with the cell positions on the same or "back" side of the module, and the outer strip 31 presents light and dark areas to identify the frame or module location; ie., the particular module within which the mechanism is located. As will be hereinafter more apparent, the front and back trans-ducer blocks 31' and 31" are spaced apart a distance corresponding to the distance of displacement of the picker mechanism B when the latter is rotated 180 be-tween opposite sides of each module.
As shown in Figures 2 and 3, the vertical guide post V is hollow and of generally rectangular cross-section to present four flat elongated surfaces 35, 36, 37 and 38 which are arranged at 45 or diagonally to the direction of travel of the mechanism along the guide rail. Surfaces 35 to 38 present guide surfaces for upper and lower sets of guide rollers 39 and 40 on opposite front and rear sides of the post, each set of rollers being journaled on the vertical motion carriage 12 to guide its movement verti-cally with respect to the tape cartridge cells. Addition-ally, the vertical motion carriage 12 includes a ring-like support 42 in which the rollers 39 and 40 are journal-ed on diametrically opposed sides so as to engage the post 78~

V adjacent to the corners formed between the front surfaces35-36 and the rear surfaces 37, 38.
In order to drive the vertical motion carriage along the post V, a flexible power transmission belt 44 is trained over a drive gear 45 which is driven off of shaft 46 of drive motor 47, and the drive belt 45 has one side extending upwardly through the hollow interior of the post V to pass over a driven pulley 48 at the upper end of the post and be clamped as at 49 to the carriage 12.
The opposite end of the belt is clamped at 50 to the platform 10. A cog-type power transmission belt is prefer-ably employed as the belt 44 in cooperation with a spur gear 45 to impart positive driving motion to the carriage along the post as well as accurate braking when a desir-~ ,i "'~! ed position is reached. The location of the vertical motion carriage with respect to the post is accurately sensed by a vertical or "Y" transducer strip 52 which is affixed to the post and is straddled by a transducer block assembly 53 on the carriage frame 42 and which in a manner similar to that of the horizontal transducer assem-bly 29-31 is provided with a bank of light-emitting diodes 54 and phototransistors 55 on opposite sides of the strip.
The vertical transducer strip 52 presents alternate light and dark areas or sensing members aligned with the cell position and reel mount station levels in order to es-tablish accurate vertical alignment of the picker mechan-ism with a desired tape cartridge cell.
As shown in Figures 2, 4 and 5, the cartridge selector mechanism B is mounted for extension transversely of the length of the library system. The mechanisrn B is positioned on one side of the vertical motion carriage 12 directly beneath and to one side of the rear roller pairs 1~3i78~

40. The mechanism has a vertical mounting plate on frame 60 which is affixed to the cylindrical support 42 of t he carriage 12 and has mounted thereon a horizontal guide rod 61 provided with bumpers 62 at opposite ends. The guide rod supports vacuum chuck assembly 64 for horizontal sliding movement toward and away from a tape cartridge.
the chuck assembly 64 including a mounting arm 65 pro-vided with bushings 66 disposed on the guide rod 61, and a vacuum chuck 67 is mounted by a projecting flange 68 within the bifurcated end 65' of the mounting arm 65 for limited swinging or pivotal movement about a pivot pin 70.
The vacuum chuck 67 has a main body portion 71 provided with an arcuate concave face 72 curving downward-ly and forwardly away from the mounting arm 65. Affixed to the arcuate face 72 is a similarly concave flexible seal 74 having an outer peripheral lip or ridge 75 of elongated generally oval-shaped configuration. Opposite side edges of the ridge 75 are of a width equal to or slightly less than the width of the peripheral edge of a tape cartridge, as shown in Figure 8, and the seal is of a length to engage the lower circumferential surface portion of the tape cartridge for approximately 45 along its length.
The seal 74 is further provided with openings 76 which communi-cate with a vacuum line 78 through internal bores in the body which is aligned with the openings 76.
The vacuum line extends from a vacuum pump and motor 79 and is provided with a poppet valve 73 in the line to control opening and closing of the line for application of a negative pressure to the vacuum chuck. The vacuum seal as described is preferably composed of a rubber or ~ . . ., ~,, .

~l~78~7~ial rubber-like material which, when it contacts the peripher-al edge of the tape cartridge will form a seal against ~ the edge of the cartridge so that when a negative pressure ;~ or suction is applied through the vacuum line will posi-tively engage the cartridge for removal from its storage position.
Translational movement of the vacuum chuck to-ward and away from a tape cartridge is controlled by a carriage drive motor 80 having its drive shaft keyed to a belt drive pulley gear 81 for a flexible power trans-mission belt 82. The belt 82 is clamped as at 84 to the side of the mounting arm and is passed over an idler wheel 86 at the leading end of the plate 60. In its retracted position, the vacuum chuck assembly 64 is normally dis-posed within an open holder 88 which is secured to one side of the plate 60. The holder includes a pair of spaced vertical brackets 90, a horizontally extending bracket 91 and pads 92 on the lower ends of the brackets 90 so that when the vacuum chuck retracts the tape cart-ridge into the holder it will rest on the pads 92.
In order to maintain a proper attitude of the vacuum chuck with respect to the frame 60, upper and lower guide rollers 93 and 94, respectively, are journaled on the mounting arm 65 for engagement with the frame. In addition, a transducer block assembly 96 straddles a transducer strip 97 to sense the position of the vacuum chuck as it is moved between the retracted position and an extended position for selection of a tape cartridge so as to cause the voltage supplied to the motor 80 to be reduced to a level sufficient to permit the picker or selector mechanism B to coast into its final position with the mounting arm 65 abutting the stops or pads 62 on the guide rod 61 at opposite ends of its travel.

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10'78~S0 : .
The entire picker mechanism B is capable of undergoing swinging or rotational movement about the vertical post V under the control of a rotational drive motor 100 disposed in housing 102 beneath the vertical ~ motion carriage 12. As shown in Figure 7, drive motor ; 100 drives a pinion 104 about a ring gear 105 to advance - the picker mechanism B between substantially diametrically opposed positions on opposite sides of the vertical post V in order that the mechanism B can select tape cart-ridges from either side of the storage module. Bumpers 106 and 106' are affixed at spaced locations on the frame 60 for engagement with the stops 107 and 108 on opposite sides of the housing 102 of the motor 100. In addition, an encoder strip 110 shown in Figures 7 and 13 is mounted on the cylindrical support 42 and is sensed by a transducer assembly 111 to cause the motor to be deenergized a predetermined distance ahead of its stopping point so that the motor picker mechanism will then coast into its final position at the end of its travel.
Operation of the tape library system can be best appreciated and understood from a consideration of the transducer strip arrangement utilized in sensing dir-ection and speed of movement, as schematically shown in Figures 9 to 13 together with the functional diagram of the speed, direction and position control circuitry, shown in Figure 14. For example Figure 9 illustrates segments of the outer frame or module address strip 31 which is utilized to designate the location of the selec-tor mechanism S with respect to a given module within thesystem. As stated earlier, the system may be comprised ~7875{) .
of one or more library storage modules M and a centrally located library control module M'. Since the system is de-signed in such a way that modules can be added or removed, and a common carriage S advances along the entire length ~; of the system, means must be provided to command the carriage S to advance to a given module and to a speci-fic reel or station location within that module. To this end, the module address strip 31 is coded with a different module number for each module in the system;
and preferably, the coding appears at each reel location within each module. As shown in Figure 9, the coding on the frame address strip is binary with the black or dark-ened areas representing a logic "ONE" and the transparent or open areas representing a logic "ZERO". Thus, when the transducer block assembly 31~ or 31" is opposite a given reel location in module 1, it will generate a correspond-ing signal which is transmitted through the interface logic of the system to the operating program. Similarly, when the selector mechanism is advanced through module 2, the transducer block 31' or 31" will generate a signal representing the number "2". As noted from Figure 9, the darkened or shaded areas are repetitive throughout the module and located opposite to each reel location so that at each reel location within the module a frame or module address number will be generated along with the reel location within that module. As further noted from the segment representing module 34, the module location is represented by the sum of the binary numbers represent-ed by the darkened areas on the strip. Moreover, the module location will be sensed either by the transducer ; ~,, .:

~78750 block 31' or 31" depending upon the side of the module from which a reel is being selected by the picker mechanism B. In other words, if the carriage mechanism S is at the end of a module, the mechanism B may be aligned opposite to a reel location either at the end of that module or at the beginning of the next module, since the picker mechanism B will be offset lengthwise of the system several reel locations along the length of the system when it is rotated from one side of the system to the other.
Referring to Figure 9, the position of the mechanism S with respect to the reel positions along opposite sides of each module are designated by the in-board and outboard transducer strips 29 and 30, there being a separate transducer strip for the reel locations along the front and back side of each module as stated earlier.
The reel transducer strips in cooperation with the trans-ducer block assemblies 29' and 30' function in a corres-ponding manner to designate each reel location within a module, and accordingly only one of the strips 30 is shown in Figure 6 for the purpose of illustration. Specifically, as shown, strip 30 for the right side reels includes an increment track with a series of five reel address tracks which again are weighted in binary form to represent the numbers "ONE", "TWO", "FOUR", "EIGHT" and "SIXTEEN". In the same manner as described with reference to Figure 9, coding of the strip is binary with the darkened areas along each track representing a logic "ONE". Only a limited portion of the strip 30 is shown in Figure 10 for reel locations "THIRTEEN" to "EIGEITEEN", each location being represented by the sum of the numbers represented by the darkened areas along the five address tracks, as - 1~78~SO

, sensed by the transducer block 30' in passing the lead-ing edge of the darkened area, or increment marker, along the increment track with that reel location. Each increment marker in succession along the increment track as represented in Figure 10 is centered with respect to a reel location. The transducer block 30' will then trans-mit a signal to the interface logic indicating the loca-tion of the mechanism S as it passes each reel location so as to permit the computer to compare with the posi-tion commanded. Considered together with the descrip-tion of Figure 9, therefore, the computer will receive signals representing location of the selector mechanism both with respect to the modules and with respect to the reel locations within the module.~
Preferably, the selector or carriage mechanism S is caused to advance between positions at a predetermin-ed rate of acceleration and deceleration in order to achieve high speed movement and readily controlled brak-ing at the stop or final position opposite to a desired reel. To this end, the mini-computer 115 as represented 14, from the operating program of the requesting computer and from that calculate the distance between the start point and end point. The trajectory of movement of the selector mechanism can then b~ calculated algarithmically so as to establish a predetermined reference velocity, including a maximum velocity, to control acceleration and deceler-ation of the mechanism S over each different given dis-tance of movement between the start point and end point.
Once movement is initiated, signals generated by the trans-ducer block 2~' or 30' in passing the leading edge of ~ .
~'' .~
each increment marker provides the mini-computer 115 with a continuing measurement of distance against time and enables it to check actual speed of movement against the actual reference velocity. If an overspeed condition is detected, an error signal is generated by the mini-computer to reduce the voltage applied to the horizon-tal drive motor 22 whereby to cause a reduction ln speed, and the converse is true in the event of an underspeed condition. Most desirably the reference velocity is es-tablished to cause the mechanism S to accelerate overthe first one-half of its travel between the start and end points followed by deceleration to the last increment marker preceding the desired reel location at the end point.
In the preferred embodiment, a maximum velocity point is established so that for extended distance of movement, the mechanism is accelerated until it reaches that velocity and then remains there until it once again intercepts the refer-ence velocity line whereupon the mechanism is decelerated over its remaining distance of travel. When the mechanism reaches the last increment marker centered with respect to the end point or desired reel location, the signal generat-ed places the computer in a "stop lock mode". Thereafter, a stop lock control circuit 116 is activated to position the mechanism at the center point of that increment marker for the desired reel location. Specifically, when the trans-ducer block 29' or 30' senses the leading edge of the mark-er on the strip 29 or 30 aligned with the desired reel loca-tion, it will cause a signal to be transmitted to X-Y in-terface logic circuit 117, at which point the distance to the center of that marker is measured by a predetermined .

:~,Q7875~) number of pulses generated by the incremental transducer 22. An up/down counter circuit 118 is pre-set to count the pulses received from the incremental transducer 22 when the circuit is placed in the stop lock mode by the stop address signal from the transducer block. When the counter has counted up to a pre-set number of pulses it will transmit a signal to a digital-to-analog converter 119 which will in turn transmit an analog signal through a power ampli-fier 120 to reduce the voltage applied to the horizontal drive motor 116. If, as a result of inertial effects or other causes, the motor should over-run the pre-set position, the up/down counter 118 will cause reversing signals to be applied through the digital-to-analog con-verter 119 to reverse the direction of the motor until the null or center position is reached and assure accurate location of the picker with respect to the reel.
If the distance of horizontal movement between start and end points is relatively short, for instance, less than fifteen reel positions, the incremental trans-ducer 22 also may be utilized by the system to regulatethe velocity of travel over the entire distance simply by comparison of the pulses generated by the incremental transducer 22 with the reference velocity established by the computer. For example, a two-phase bidirectional LB 125-251LlB-l incremental encoder manufactured by Litton Industries may be employed with a permanent magnet drive motor of the type manufactured by 4020-63 Indiana General Corp. where the incremental encoder output is 250 pulses for each revolution, each pulses representing 0.0118 inches of movement. The transducer described provides a two-phase output, 90 out of phase so that 250 square wave pulses are generated for each revolution of the motor.

` ~7#~50 The stop lock control circuit will be hereinafter describ-ed in more detail in conjunction with the description of the functional diagram of Figure 14.
Referring to Figure 11, in a manner very much similar to that described with respect to horizontal motion of the mechanism S, the vertical motion carriage 12 operates both in a velocity mode for moving between vertically spac-ed reel locations and a stop lock mode for holding and final positioning of the carriage 12. By sense data re-ceived from the transducer block 53, the vertical motioncarriage 12 is accelerated from its initial position to a point half-way to the new or end point required. At the half-way point, the carriage begins to decelerate and to stop at the stop address. Acceleration and deceleration rates are constant so that the relationship between dis-tance traveled to velocity is the same for each move.
In carrying out vertical motion the vertical transducer motion strip 52 is coded as shown in Figure 11 to provide an address system divided into zones defining each differ-ent reel level along opposite sides of the module, the pre-load and post-load stations N and O being aligned with the reel levels. In the preferred form, five rows of reels ; extend along each side of the module, and the transducer strip 52 is correspondingly divided into five zones, the pre-load and post-load stations being aligned with the third and fourth levels. The reel levels or zones Y-l to Y-5, are represented in binary form by the transducer track numbers 1 to 3 which are weighted in binary form by bits "ONE", "TWO" and "FOUR", respectively, so that again each reel level is denoted by the sum of the numbers re-presented by the darkened areas of the tracks 1 to 3 as sensed by the transducer block 53 in passing over their "` 1~7~750 leading edges. Track 4 operates in a manner similar to the increment track on strip 30 to place the circuit in a stop lock mode when the leading edge of the increment marker for a given end point or reel level is sensed.
Finally, track 5 is a timing track which serves as a dis-tance measuring track to monitor progress of the movement as well as to control the speed of travel of the carriage 12 and to indicate its direction of travel. Advancement of the carriage is monitored by counting the alternate light and dark areas or timing markers on track 5, as 11 by calculating velocity in the minicomputer by measuring the time taken to travel between leading edges of successive markers. Simultaneously, directional movement is determin-ed by a pair of light-emitting diodes represented at 53' spaced from each other one-half the distance of each timing marker or track 5. A phase detector in the interface logic circuit 117 determines the direction of travel of the car-riage 12 by sensing the order of receiving signals from each of the diodes 53' in passing the leading edge of each timing marker. Similarly, in the stop lock mode, transducer block 53 includes another pair of light-emitting diodes and photo-transistors straddling track 4 of the transducer strip, the spacing between these diodes corresponding to the length of the increment markers. The output from the photo-transistors for track 4 is applied to a differential amplifier 122 which through power amplifier 123 applies the necessary control signals to the motor 47 until the increment marker is centered between the light-emitting diodes. The drive motor 47 also may be the same type of permanent magnet drive motor as used for the selector mechanism S.

1~78750 Referring to Figure 12, movement of the picker mechanism B toward and away from a tape cartridge is sensed by a transducer strip 97 which again includes al-ternate light and darkened areas, the darkened areas being weighted in binary form so that the transducer block 96 will generate signals indicating direction of movement and disposition of the picker mechanism at specified points along its travel as represented in Figure 12. It is believ-ed that Figure 12 is self-explanatory as to the various positions sensed by the transducer block and, since the picker mechanism travels over a fixed distance both toward and away from the tape cartridges, the drive motor may be driven at a constant velocity until it reaches a predeter-mined distance ahead of its end or stop point, at which point the voltage is reduced to the motor to permit the mechanism to coast home to its stop position.
Rotational movement of the picker mechanism B
is sensed by the transducer strip 110, as shown in Figure 12, which is located on the support frame 42 and is strad-: 20 dled by the transducer block assembly 111. Again, since rotation of the picker mechanism is over a fixed distance, the rotational drive motor 100 can be driven at a constant rate of speed between the dynamic braking points, as re-presented in Figure 13, at which point voltage to the motor is reduced to permit the picker mechanism to coast down to its end point abutting one of the rotational stops 107 or 108 on the motor housing.
Figure 14 diagrammatically illustrates the interrelationship between various movements of the selec-tor mechanism vertical motion carriage 12 and picker mechan-ism B. As shown, the operating program for the system 7~5~

maY be applied through a mini-computer, such as, a model DEC-PDP-11-05 manufactured by Digital Equipment Corporation of Maynard, Massachusetts and which translates move commands from a requesting computer (not shown), such as an IBM
360 and to convert those commands to instruction signals compatible with the system for control of speed, direction and position. The mini-computer establishes all critical addresses, such as "start", "maximum velocity", "declerate", "stop lock", and "fast stop". Horizontal and vertical movement of the selector mechanism S and vertical motion carriage 12 are simultaneously directed and controlled through the X-Y interface 117 which acts as a buffer be- ~ -tween the mini-computer and the external analog circuits and translates the computer control signals to a particular system function. When an operating command is received from the requesting computer, X and Y movement of the mechanism S and carriage 12 are ordered simultaneously while operating independently of one another to reach a given reel location. Thus if the vertical distance of movement is relatively short the motion carriage 12 will enter into a stop lock mode and reach its final vertical position well ahead of the final horizontal position of the mechanism S. Once movement is initiated, the signals generated by the various transducers in the X-Y subsystem are received through the X-Y interface and are processed by the mini-computer to sense the direction and distance of movement of the mechanism toward a desired end point.
As described, the mini-computer will compare the velocity information received with the reference velocity and correct for overspeed or underspeed conditions. When the mechan-ism S approaches its end point opposite to a given reel ~ . . .

"` 1~7~50 location, the stop lock control circuits as described for the X and Y movement are activated to center the picker mechanism with respect to a given reel. Relay circuits 128 and 129 are associated with the drive motors 16 and 47, respectively, to permit immediate breaking of the circuit in the event that either motor should run out of control or other malfunction should occur in the system.
Other sections of the X-Y drive system are re-presented in Figure 14 and will not be specifically enum-erated as they form no part of the present invention andconsist of conventional circuitry such as the line re-ceivers which receive the transducer data from the trans-ducers as described and convert them to standard logic levels together with the necessary line drivers to process the transducer signals and transmit to the mini-computer.
In addition, the control circuit includes an ARM interface 125 which applies the necessary control sig-nals to the automatic reel mount unit, and a Z-0 inter-face 126 applies the necessary control signals to the picker mechanism B in controlling the translational or Z
movement and the rotational or 0 movement of the picker mechanism. Briefly, the Z-~ control circuitry for the - picker mechanism is not activated until the vertical mo-tion carriage 12 has been advanced to the desired reel location, at which point the picker mechanism is activat-ed to advance the vacuum chuck into engagement with the reel, remove it from its storage location, and advance it either to or from the pre-load station of the automatic reel mount unit. Accordingly, the Z-0 control circuit in-cludes the necessary controls of the vacuum pump to selec-tively engage a tape cartridge in removing it from its `-- 1(11'7~750 storage location and to release the tape cartridge when it `
has reached its intended destination.
From the foregoing, it will be evident that the modular tape library system of the present invention is capable of highly efficient and rapid retrieval of in-formation stored on magnetic tape reels under operating command from a computer. The mechanism itself insures safe reliable handling of the tape cartridges and further permits removal and replacement of the tape cartridges from and into their storage locations while other tape cartridges are being processed independently of the sel-ector mechanism S by the automatic reel mount unit. Thus, in succession, the selector mechanism S is activated to undergo highspeed movement under controlled acceleration and deceleration to a given reel location. When the picker mechanism B is centered with respect to the reel, it is activated to advance the vacuum chuck into engagement with the peripheral edge of the tape cartridge containing ; the reel whereupon the vacuum pump is energized to apply the necessary vacuum to the vacuum chuck to positively en-gage the tape cartridge. Thereafter, the vacuum chuck is J,~ retracted to advance the tape cartridge into the holder -~ and the selective mechanism S is once again energized to transfer the tape cartridge to the pre-load station of the automatic reel mount unit for that module. The tape cart-ridge is then advanced into alignment with the receptacle on the pre-load station, the vacuum released in order to deposit the tape cartridge in the receptacle, after which the picker mechanism B is retracted away from the pre-load station. It is then free to be advanced to another reel location for selection of another tape cartridgel or can be advanced to the post-load station on the automatic reel . . .

mount unit to pick up a processed cartridge and return it to its storage position. The modular library system as described permits addition of modules to the system for increased storage and processing capacity. As each module is added to the system, another guide rail section and additional transducer strip sections must also be added for the purpose of sensing the module and reel locations within each added module. Most desirably, each module has its own automatic reel mount unit in order that the tape cartridges can be processed in the same module in which they are stored.
It will be understood that while the preferred form of the invention has been illustrated and described, changes in construction and arrangement may be made without departing from the spirit and scope of the invention as de-fined by the appended claims.r ~ 31 ~

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In an automated tape library system wherein record tape containers are mounted in rows of storage cells along opposite sides of an elongated horizontal guide track, the combination therewith of:
self-propelled carriage means including a vertical post mounted for horizontal movement along said guide track;
tape container selector means mounted for movement vertically of said self-propelled carriage means, said tape container selector means including tape container engaging means movable in a horizontal direction transversely of said horizontal guide track;
horizontal drive means for advancing said self-propelled carriage means along said horizontal guide track;
vertical drive means for advancing said tape container selector means vertically of said self-propelled carriage means to a position aligned with a tape container to be removed;
selector drive means for advancing said tape container engaging means toward and away from a storage cell for selected replacement or removal of a tape container;
and rotational drive means for rotating said tape container engaging means about said vertical post between opposite sides of said rows of storage cells.

2. In the system according to claim 1, said tape con-tainer engaging means including a vacuum chuck assembly having an arcuate flexible seal member conforming to the outer peri-phery of said tape container.

3. In the system according to claim 1, said horizon-tal drive means being operative to advance said carriage means between positions under controlled acceleration and deceler-ation.

4. In the system according to claim 1, said vertical post being hollow and of generally rectangular cross-section with its surfaces extending diagonally to the direction of travel of said selector means, said selector means including a rotatable support frame and guide roller means for guiding said frame vertically along the surfaces of said vertical post.

5. In the system according to claim 4, said vertical drive means including a drive motor and a power transmission belt having a portion thereof clamped to the said selector means.

6. In an automated tape library system wherein tape containing cartridges are stored in rows of storage cells disposed along opposite sides of a horizontal guide track, the combination comprising;
a cartridge mount unit including a tape deck mounted on one side of said system, a tape cartridge loading station adapted to receive a tape cartridge removed from a storage cell and a tape unloading station adapted to receive a tape cartridge from said deck, and means for advan-cing a tape cartridge between said tape cartridge loading station, tape deck and tape cartridge unloading station;
self-propelled carriage means including a vertical post mounted for horizontal movement along said guide track;
cartridge selector means mounted for move-ment vertically of said self-propelled carriage means, said cartridge selector means including cartridge engaging means movable in a horizontal direction transversely of said guide track;

first horizontal drive means for advanc-ing said self-propelled carriage means along said horizontal guide track;
vertical drive means for advancing said cartridge selector means vertically of said self-propelled carriage means in correlated relation with horizontal advance-ment of said self-propelled carriage means to a position aligned with a cartridge to be removed;
second horizontal drive means for advan-cing said cartridge engaging means toward and away from a storage cell for selected replacement or removal of a tape cartridge;
rotational drive means for rotating said tape container engaging means about said vertical post between opposite sides of said rows of storage cells.
control means associated with said self-propelled carriage means and cartridge selector means for ad-vancing said cartridge engaging means to a position aligned with a selected one of said loading station, said unloading station, and one of said storage cells, and position sensing means operative when said cartridge engaging means is aligned by said control means to activate said cartridge engaging means for advancement toward a respective one of said storage cells, loading and unloading stations.

7. In the tape system according to claim 6, said cart-ridge engaging means including vacuum chuck means having an arcuate flexible seal at one end conforming in contour to a peripheral edge portion of each tape cartridge whereby to es-tablish a sealed contact with the peripheral edge of a cart-ridge and vacuum applying means communicating with the interior of said seal to establish a vacuum therein when said seal en-gages a tape cartridge whereby said tape cartridge is positively engaged by said flexible seal for removal from a stored position and advancement with said carriage means to another selected position, and vacuum release means associated with said vacuum applying means to selectively release the vacuum from said vacuum chuck when the tape cartridge is advanced to the next position.

8. In the system according to claim 7, said cartridge engaging means being movable transversely of said guide track between an extended cartridge selecting position for engage-ment of said vacuum chuck means with a selected tape cartridge and a retracted position on said selector means, and holder means cooperating with said vacuum chuck means to retain a selected tape cartridge on said selector means in the retracted position.

9. In the system according to claim 6, said vertical drive means advancing said cartridge selector means vertically of said self-propelled carriage means simultaneously with hori-zontal advancement of said self-propelled carriage means.

10. In an automated tape library system wherein tape containing cartridges are stored in rows of storage cells dis-posed along opposite sides of a horizontal guide track the conbination comprising:
self-propelled carriage means including a vertical carriage mounted for horizontal movement along said guide track;
cartridge selector means mounted for move-ment vertically of said self-propelled carriage means, said cartridge selector means including cartridge engaging means movable in a horizontal direction transversely of said guide track;
first horizontal drive means for advancing said self-propelled carriage means along said horizontal guide track, cell location sensing members spaced at preselected inter-vals corresponding to the location of each cell in a row in parallel relation to said guide track, and horizontal sensing means on said self-propelled carriage means for generating a signal in response to movement past each one of said cell location sensing members;
horizontal position control means responsive to each signal generated by said horizontal sensing means to transmit a speed control signal to said first horizontal drive means whereby to cause said first horizontal drive means to accelerate said self-propelled carriage means between a start position and end position along a predetermined number of cell location sensing members followed by deceleration until an ap-proach position is reached adjacent to and ahead of each pre-determined end position;
vertical drive means for advancing said cartridge selector means vertically of said self-propelled carriage means to a position aligned with a cartridge to be removed;
second horizontal drive means for advancing said cartridge engaging means toward and away from a storage cell for selected replacement or removal of a tape cartridge;
rotational drive means for rotating said cartridge engaging means about said vertical post between opposite sides of said rows of storage cells; and limit stop means operative in response to deceleration of said self-propelled carriage means to the ap-proach position to precisely align said self-propelled carriage means with the end position to be reached.

11. An automated tape library system according to claim 10, said limit stop means including a separate set of sensing members centered with respect to each horizontal position, and said limit stop means being operative to center said self-pro-pelled carriage means with respect to each desired end point.

12. An automated tape library system according to claim 10, including a memory means having constant velocity control signals causing said first horizontal drive means to operate in a constant velocity mode when the distance of travel of said self-propelled carriage means exceeds a predetermined number of horizontal positions.

13. An automated tape library system according to claim 10, including vertical sensing members and limit stop means aligned with each row of cells, vertical sensing means associ-ated with said cartridge selector means and operative to gen-erate a signal in response to movement past each vertically spaced sensing member and said limit stop operative to center said selector means with respect to a desired cell level.

14. An automated tape library system according to claim 10, a series of storage cells being positioned in storage modules, there being a plurality of storage modules arranged in end-to-end relation and said guide track extending along the center aisle of said modules, and module sensing means between each module and said carriage means for generating a signal representing the location of said carriage means with respect to said modules.

15. An automated tape library system according to claim 14, said module sensing means including a plurality of sensing members arranged on a common strip extending lengthwise of said modules in closely spaced parallel relation to said cell loca-tion sensing members, said cartridge engaging means being offset from the rotational axis of said cartridge selector means so that for a given disposition of said carriage means along the length of said guide track said cartridge engaging means is ro-tatable between diametrically opposed positions in facing rela-tion to tape cartridges on opposite sides of said guide track longitudinally displaced from one another, said cell location sensing members including cell location sensing means for each side of said guide track in which said sensing means for the cell positions on one side is longitudinally displaced from the sensing means for the opposite side of said guide track a distance corres-ponding to the longitudinal displacement of said cartridge en-gaging means when rotated between diametrically opposed posi-tions about the rotational axis of said cartridge selector means.

16. An automated tape library system according to claim 10, said horizontal position control means including an incre-mental encoder operative to generate a series of pulses in response to advancement of said carriage means by said horizon-tal drive means along said guide track, said limit stop in-cluding means responsive to movement of said carriage means past said approach position to count the pulses from said incremental encoder and to stop said carriage means a predeter-mined number of pulses past the approach position.