Note: Descriptions are shown in the official language in which they were submitted.
1078750
.
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
.... , ~
. ', ' , . .~ - . ,. , : ;
~'
1~78750
~.
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
10787S0
,:
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.
;
-- 4 --
8750
~'
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
~:
:~
~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.
~ .
,
1(37~37SO
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
-- 8 --
8750
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
-- 10 --
.
,. 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.
-- 11 --
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
- 14 -
,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
- 15 -
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
- 16 -
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.
- 18 -
- ::
: ::
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
-- 19 --
~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
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~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
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78750
.~
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
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.
:~,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.
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` ~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
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"` 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.
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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
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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
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~ . . .
"` 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
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`-- 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
- 30 -
. . .
8750
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
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