Tape drive system

A thermomagnetic layer on a slave tape has a Curie temperature above which it loses, and below which it stores, an image. Such layer is heated above the Curie temperature just before such layer records an image. To compensate for image stretching in such layer by the heat, the lines in a raster scan on the mirror-master tape are lengthened relative to such lines on a master tape during an image transfer between the tapes. To accomplish this, a rotary member holding the mirror-master tape has a larger diameter than, and rotates at the same angular speed as, a rotary member holding the master tape. To inhibit the slave tape separation from the heater by water vaporization in the thermomagnetic layer, (1) the heater heats such layer while the slave tape moves in a direction opposite to its movement during the image transfer or (2) a microwave oven heats such layer. The slave tape length may be determined from (1) the capstan revolutions for a reference tape of a given length and for the full length of the slave tape or (2) the angular revolutions of the slave tape supply and take-up reels at successive time instants, and the radius of the slave tape supply and take-up reels without tape on such reels. A sufficiently long slave tape may then be wound on the supply reel through an angular revolution of the particular reel dependent upon the image length on the master tape.

This invention relates to a system for, and a method of, recording an image 
on a slave tape. More particularly, the invention relates to a system for, 
and a method of, recording an image on a slave tape having a 
thermomagnetic layer with a Curie temperature above which the layer loses 
any image and below which the layer is capable of recording and storing an 
image. The invention particularly relates to a system for, and a method 
of, recording an image on a thermomagnetic layer of a slave tape with an 
accuracy and fidelity greater than that which has been capable of being 
attained in the prior art. 
Visual and audio information is often stored on a tape for playback at a 
subsequent time. For example, visual and audio information relating to 
popular motion pictures is stored on tapes. These tapes are rented or sold 
at neighborhood stores. A popular movie such as "Aladdin" or a movie 
winning an Academy Award has millions of taped copies distributed to 
satisfy the demands of purchasers and renters. Substantially all of these 
taped copies have to be made available at a pre-selected release date in 
order to satisfy the pent-up demand of viewers for such taped copies. 
Although the demand for movie rentals and sales is great, it still seems 
to be increasing significantly from year to year. 
Visual and audio information on tapes is not only provided in the form of 
movies for entertainment. It is also provided in large volume for business 
purposes. For example, large corporations deliver messages in the form of 
tapes to their sales personnel to acquaint such sales personnel with the 
construction, operation and advantages of new products. Since large 
corporations employ large numbers of sales personnel, many copies of 
such-messages have to be prepared for distribution to such sales 
personnel. 
The visual and audio information on most tapes is in magnetic form. One 
reason is that information in magnetic form can be relatively easily and 
inexpensively reproduced. For example, most reproducing apparatus in the 
home use magnetic heads to read the information stored magnetically on the 
tapes when the tapes are inserted into such apparatus. Another reason is 
that tapes with information recorded in magnetic form are less expensive 
to reproduce than tapes in other forms such as in optical form. 
One type of tape for recording information in magnetic form has a 
thermomagnetic layer on the tape. The thermomagnetic layer may be formed 
from a suitable material such as chromium dioxide. The thermomagnetic 
layer has a Curie temperature at or above which any magnetic information 
on the tape is destroyed and below which magnetic information can be 
recorded on the tape. Thermomagnetic tape is advantageous because 
information can be recorded on the thermomagnetic tape at a temperature at 
or somewhat below the Curie temperature by pressing a master tape against 
the thermomagnetic layer on the slave tape at such a temperature. This 
causes the surface of the thermomagnetic layer to become cooled to a 
temperature below the Curie temperature by contact with the cool surface 
of the master tape. As the thermomagnetic layer cools to a temperature 
below the Curie temperature, the magnetic information on the magnetic tape 
becomes transferred to the thermomagnetic layer on the slave tape. The 
information on the master tape thus becomes transferred in mirror form to 
the thermomagnetic layer on the slave tape without having to use any 
magnetic heads to write information on the slave tape. 
There is at least one apparatus now in use for transferring information in 
magnetic form on a master tape to a thermomagnetic layer on a slave tape. 
Although this apparatus is fast, it is large, cumbersome and expensive, 
and requires excessive electrical power. With the millions of copies that 
have to be made of a single movie such as the movie winning an Academy 
Award, it would be desirable to provide apparatus which is relatively 
inexpensive and which transfers information from a master tape to a slave 
tape in a minimal period of time. For example, it would be desirable to 
provide equipment which is relatively inexpensive and which transfer 
information from a master tape to a slave tape in a minimal period of 
time. For example, it would be desirable to provide equipment which is 
relatively inexpensive and which reproduces a two (2) hour movie in 
approximately thirty (30) to sixty (60) seconds without any need for using 
magnetic reproducing heads. Because of the desire, and actually the need, 
for such apparatus, a considerable effort has been devoted, and a 
significant amount of money has been expended, to develop apparatus which 
meet such criteria. In spite of such effort and such money expenditure, no 
satisfactory apparatus meeting such criteria has been provided to this 
date. 
The invention disclosed and claimed in application Ser. No. 07/733,174 
abandoned filed by us on Jul. 19, 1991 for a "Tape Duplicating System" and 
assigned by us to the assignee of record in this application provides 
apparatus which more than meets the criteria specified in the previous 
paragraph. It is able to record a two (2) hour movie in approximately 
thirty (30) to sixty (60) seconds such that the duplicated copy has the 
visual and audio fidelity of the original or master copy. It is compact so 
that it occupies relatively little space. This is important when a large 
number of apparatuses are used simultaneously in an enclosure such as a 
room to make duplicate copies. For example, the apparatus can be used to 
transfer the information on a master tape to a mirror-master tape, and 
subsequently the same apparatus can be used to transfer the information on 
the mirror-master tape to a slave tape, all without using recording heads. 
In one embodiment of the invention disclosed and claimed in application 
Ser. No. 07/733,174 abandoned, a mirror-master tape moves between first 
supply and take-up reels over a pinch roller. A slave tape moves between 
second supply and take-up reels over a capstan. First and second guides 
can be respectively constructed and adjustably positioned to regulate the 
movement of the mirror-master and slave tapes to aligned positions on the 
pinch roller and the capstan. A heater disposed between the capstan and 
the second guide heats only a thermomagnetic layer on the slave tape to at 
least the Curie temperature. The heater is adjustable in position to 
facilitate the movement of the slave tape to the aligned position on the 
capstan. A brake shoe between the capstan and the second supply reel 
controls the tension of the slave tape and damps any variations in the 
tension of the slave tape. A brake shoe between the pinch roller and the 
first supply reel controls the tension of the mirror-master tape and damps 
any variations in the tension of the mirror-master tape. 
The pinch roller is movable to a first position, locked in position 
relative to the capstan, in which it abuts the capstan to facilitate the 
transfer of magnetic information from the master tape to the slave tape. 
In this disposition, the pinch roller locks the heater in a fixed position 
relative to the capstan. The pinch roller and the associated guide are 
movable to a second position displaced from the capstan to facilitate the 
disposition of the mirror-master tape on the pinch roller and the slave 
tape on the capstan. The heater is pivotable relative to the capstan to 
facilitate the disposition of the slave tape on the capstan. The capstan, 
preferably of a unitary construction, receives forces to maintain the 
rotational axis of the capstan substantially constant. 
Since the tapes pass over surfaces between the brake shoes and the capstan 
and the pinch roller, the tensions on the mirror-master and slave tapes 
are not as closely regulated at the position of transfer of the magnetic 
information from the mirror-master tape to the slave tape as might 
otherwise be desired. Specifically, the tapes pass over alignment guides 
which have a variable friction with time and physical conditions. This 
variable friction inhibits a precise regulation of the tape tensions at 
the abutting positions between the capstan and the pinch roller where the 
magnetic information is transferred to the slave tape. 
In one embodiment of the invention disclosed and claimed by us in 
application Ser. No. 07/886,688 U.S. Pat. No. 5,392,976 filed by us on May 
19, 1992, for a "Tape Duplicating System" and assigned by us of record to 
the assignee of record of this application, a mirror-master tape movable 
in a closed loop including a pinch roller transfers a mirror-image to a 
slave tape movable in a closed loop including a capstan. A thermomagnetic 
layer on the slave tape has a Curie temperature above which magnetic 
information is destroyed and below which magnetic information can be 
recorded on such layer. The thermomagnetic layer is heated above the Curie 
temperature and is accordingly lengthened by thermal expansion just before 
the slave tape reaches the capstan. 
A first guide contiguous to the heater regulates the tension of the slave 
tape. A downstream portion of a peripheral surface, preferably defining a 
cylindrical segment, on the guide receives a pressurized fluid for sensing 
the tape tension in accordance with the tape width, the spacing from the 
axis of the peripheral surface and the fluid pressure. An upstream portion 
of the peripheral surface receives a vacuum adjustable to vary the spacing 
between the slave tape and the downstream portion. This regulates the tape 
tension. 
The mirror-master tape is lengthened by a second guide having the same 
construction as the first guide to compensate for the lengthening of the 
slave tape by the heater and the first guide, thereby producing a true 
mirror-image on the slave tape after the slave tape has cooled to the 
ambient temperature. Each of the mirror-master tape and the slave tape has 
a particular product of the Youngs modulus, tape width and tape thickness 
to provide a controlled strain on the tape when the tension on the tape is 
regulated. 
The invention disclosed and claim in application Ser. No. 07/886,688 
provides apparatus for, and methods of, regulating the tension of the 
mirror-master tape at a position contiguous to the pinch roller and for 
regulating the tension of the slave tape at a position contiguous to the 
heater, which is in turn contiguous to the capstan. The apparatus and 
method of application Ser. No. 07/886,688 are adapted to be used in the 
apparatus and method of co-pending application Ser. No. 07/733,174 and to 
constitute an improvement in the apparatus and method of co-pending 
application Ser. No. 07/733,174. Co-pending application Ser. No. 
07/733,174 also provides a master tape and a slave tape which may be 
constructed especially for the apparatus and method of the invention 
disclosed in such application to obtain all of the advantages provided by 
the apparatus and method of such application. 
In one embodiment of the invention disclosed and claimed in application 
Ser. No. 08/026,697 pending filed by us on Mar. 5, 1993, for a "Tape 
Duplicating System" and assigned of record to the assignee of record of 
this application, a mirror-master tape moves from a first supply reel to a 
first take-up reel in a first cassette. A slave tape moves from a second 
supply reel to a second take-up reel in a second cassette. A pinch roller 
locked in a first position between the first supply and take-up reels 
abuts a capstan between the second supply and take-up reels to transfer to 
the slave tape the image on the mirror-master tape. At the end of such 
transfer, a signal sensing the completion of the transfer causes the pinch 
roller to be unlocked and to be moved to a second position displaced from 
the first position. In this position, the second cassette is replaceable 
by another one of the second cassettes for an image transfer from the 
mirror-master tape to a slave tape to such other one of the second 
cassettes. 
In the invention disclosed and claimed in application Ser. No. 08/026,697 
(attorneys file D-2666) filed by Alfred M. Nelson and Robert P. Adams on 
Mar. 5, 1993, and assigned of record to the assignee of record in this 
application, the rotations of the supply reels produce eccentricities 
which vary the tensions of the tapes as the supply reels rotate. These 
tension variations are compensated at positions before the pinch roller 
and the capstan by springs guide the tapes and by damping members attached 
to the springs. The damping members are pre-stressed to provide damped 
compliances in accordance with the tension variations. Stiffeners are 
attached to the spring ends to provide for the compliances by the springs. 
Application Ser. No. 08/026,697 also discloses and claims a capstan which 
may be hollow, non-conductive, and non-magnetic to receive a magnetic head 
within the capstan. A constant amplitude alternating signal applied to the 
head to apply initially rising and then decaying amplitudes to the tape as 
it is displaced from the head erases any image on the slave tape by 
providing a magnetizing force greater than that of the slave tape but less 
than that of the mirror-master tape. Thus, the image on the mirror-master 
tape is transferred to the slave tape by the abutting tape relationship. 
In one embodiment of this invention, apparatus is provided for sequentially 
transferring a plurality of slave cassettes from a supply station and for 
processing the slave tapes in such slave cassettes to obtain a transfer to 
the slave tapes of an image on a mirror-master tape. The apparatus also 
provides for moving the slave cassettes to another station after the 
transfer of the image to the slave tapes and for storing the slave tapes 
in a stacked relationship in such other station. The apparatus provides 
such image transfers in a minimal time and with a minimal number of 
components and with a high resolution in the transfer of the image on the 
mirror-master tape to the slave tapes. The invention also includes methods 
of providing the functions specified above in this paragraph. 
In one embodiment of the invention disclosed and claimed in application 
Ser. No. 08/028,240 pending filed by Alfred M. Nelson, Charles E. Redman 
and Alan N. Raffaelli on Mar. 9, 1993, for "Tape Duplicating Apparatus and 
Method", slave cassettes each including a slave tape and having a 
peripheral groove are stacked in a first station. Gripping fingers are 
movable into the groove in the forward cassette, and into the groove in 
the next cassette, in the station grip the forward cassette. During the 
pivoting of the forward cassette to a second station, a cover on the slave 
cassette is pivoted to expose the slave tape. At the second station, the 
threading arms are moved from retracted to extended position. 
The slave cassette and the threading arms are then moved to a third station 
planar with a pinch roller which is displaced from the capstan. The 
threading arms are then retracted. With a mirror-master tape disposed on 
the pinch roller, the pinch roller is moved to a second position abutting 
the capstan. The pinch roller and capstan are then rotated to transfer the 
image on the master tape to the slave tape such that the image beginning 
is at the slave tape beginning. The pinch roller is moved to the displaced 
position; the threading arms are extended; the cassette is moved to the 
second station to decouple the slave tape from the capstan; and the 
threading arms are retracted. 
This invention provides a system for, and a method of, enhancing the 
accuracy with which an image on a master tape is duplicated on a slave 
tape. The system and method of this invention compensate for the 
stretching of the slave tape as a result of the elevated temperature in 
the slave tape at the time of the transfer of the image to the slave tape. 
Because of this compensation, the image on the slave tape after the 
contraction of the slave tape with the temperature reduction to ambient 
temperatures is a duplicate of the image on the master tape. 
The system and method of this invention also provide for an efficient 
operation of the heater over an extended period of time without any 
deterioration in the heater operation. The system and method of this 
invention further provide for an accurate determination of the full length 
of the slave tape and an accurate determination of the portion of this 
full length for receiving the image on the master tape. In this way, the 
slave tape can be wound on the supply reel in the slave tape cassette to 
such portion of the full length of the slave tape while the image on the 
mirror-master tape is transferred to the slave tape, thereby placing the 
slave tape cassette in readiness for the image on the slave tape to be 
provided to a viewer. 
The cassette is then moved to a position where belts are coupled to the 
cassette and the gripping fingers are thereafter released from the 
cassette. The belts then move the cassette to the mouth of a fourth 
station. Pins are rotated to position the cassette properly relative to 
the mouth of the fourth station. Continued pin rotations produce a 
movement of the cassette through the mouth and into the fourth station. 
In one embodiment of the invention, a thermomagnetic layer on a slave tape 
has a Curie temperature above which it loses, and below which it stores, 
an image. Such layer is heated above the Curie temperature just before 
such layer records an image. To compensate for image stretching in such 
layer by the heat, the lines in a raster scan on the mirror-master tape 
are lengthened relative to such lines on a master tape during an image 
transfer between the tapes. To accomplish this, a rotary member holding 
the mirror-master tape has a larger diameter than, and rotates at the same 
angular speed as, a rotary member holding the master tape.

Basic aspects of the system constituting this invention are disclosed and 
claimed in application Ser. No. 07/733,174 filed by Alfred M. Nelson and 
Robert P. Adams on Jul. 19, 1991, for a "Tape Duplicating System" and 
assigned of record to the assignee of record of this application. 
Improvements in this system are disclosed and claimed in application Ser. 
No. 07/886,688 filed by Alfred M. Nelson and Robert P. Adams on May 19, 
1992, for a "Tape Duplicating System" and assigned of record to the 
assignee of record of this application. Additional improvements are 
disclosed and claimed in application Ser. No. 08/026,697 filed by Alfred 
M. Nelson and Robert P. Adams on Mar. 5, 1993, for a "Tape Duplicating 
System" and assigned of record to the assignee of record of this 
application. Other improvements are disclosed and claimed in application 
Ser. No. 08/028,240 filed by Alfred M. Nelson, Charles E. Redman and Alan 
N. Raffaelli on Mar. 9, 1993, for a "Tape Duplicating Apparatus and 
Method". If any additional information should be needed to complete the 
disclosure of the invention claimed in this application, applicants intend 
to have such co-pending applications complete the disclosure. This is 
particularly true since applicants provide only a limited disclosure in 
this application of some of the features common to the co-pending 
applications. 
In one embodiment of the invention generally indicated at 11, a 
mirror-master tape 10 (FIG. 1) is provided with a mirror image of 
information such as visual pictures and aural sound to be reproduced on a 
slave tape 12. Preferably the mirror-master image of the visual and aural 
information is recorded in magnetic form on the mirror-master tape 10. The 
mirror-master image may be recorded in either analog or digital form. The 
visual and aural information may be provided in a layer of a magnetizable 
oxide such as an iron oxide on the surface of the mirror-master tape. The 
magnetizable oxide may be formed in a conventional manner on the 
mirror-master tape 10. 
The slave tape 12 (FIG. 1) preferably has a thermomagnetic layer on the 
tape. The thermomagnetic layer may be formed on the slave tape 12 from a 
suitable material such as chromium dioxide in a manner well known in the 
art. The thermomagnetic layer preferably has a Curie temperature above 
which magnetic information in the thermomagnetic layer is destroyed and 
below which the magnetic information on the mirror-master tape can be 
transferred in the mirror image to the thermomagnetic layer 14 on the 
slave tape by contact between the master and slave tapes. Preferably the 
image transfer occurs at a temperature close to the Curie temperature. 
When this occurs, the image transfer can occur by pressing the 
mirror-master and slave tapes together and can occur without any need to 
provide magnetic heads for transferring the magnetic information from the 
mirror-master tape 10 to the thermomagnetic layer on the slave tape 12. It 
will be appreciated that the magnetic layer on the mirror-master tape 10 
may also be formed from a thermomagnetic material. It will be further 
appreciated that the slave tape 12 does not have to have a thermomagnetic 
layer and that the image can be magnetically transferred from the 
mirror-master tape 10 to the slave tape 12 by the other techniques than 
thermomagnetic techniques. 
The mirror-master tape 10 can be initially wound on a supply reel 16 and 
can then be unwound from the supply reel 16 and wound on a take-up reel 
18. The unwinding of the mirror-master tape 10 from the supply reel 16 can 
be provided by a capstan motor 13 (FIG. 1) and the winding of the master 
tape on the take-up 18 reel can occur through the operation of a take-up 
motor 20 (FIG. 1). The reels 16 and 18 and the take-up motor 20 can be 
constructed in a conventional manner as in a video cassette 21 found in 
many homes. Similarly, a supply reel 22, a take-up reel 24 and a take-up 
motor 26 can be provided in a video cassette 28 for the slave tape 12. The 
cassettes 21 and 28 can be those used in video cassette recorders (VCR) 
for some time available commercially for showing home movies. 
FIG. 1 shows a system for transferring the image on the mirror-master tape 
10 to the slave tape 12. The mirror-master tape 10 extends from the supply 
reel 16 over a pin 30 in the cassette 21 to tensioning apparatus generally 
indicated at 32 for maintaining a substantially constant tension on the 
mirror-master tape regardless of variations in tape tension resulting from 
eccentricities in the rotation of the supply reel. The tensioning 
apparatus 32 is disclosed in detail and claimed in application Ser. No. 
08/026,697 (attorneys file D-2666). The tape 10 is disposed on a spring 34 
in the tensioning apparatus 32 and is then extended around pins 36 and 38. 
The tensioning apparatus 32 and the pins 36 and 38 are disposed on a 
member 40 pivotable as at 42 between an operative position shown in solid 
lines in FIG. 1 and a position displaced in a counterclockwise direction 
from the operative position as shown in FIGS. 5 and 6. The tensioning 
apparatus 32 may be considered as an articulator when the flow charts 
shown in FIGS. 29-35 for providing subroutines are discussed subsequently 
in this specification. 
The tape 10 then extends over a guide generally indicated at 44 in FIG. 1. 
The construction and operation of the guide 44 are fully disclosed and 
claimed in co-pending application Ser. No. 07/886,688. The guide 44 
receives a vacuum from a source 46 at its upstream end in the direction of 
tape movement and air under pressure from a source 48 at its downstream 
end. In this way, the tension of the master tape 10 is regulated at a 
substantially constant value just before the mirror-master tape moves to 
the periphery of a pinch roller 50. The mirror-master tape 10 then extends 
around a pin 52 at the end of a dancer arm 54, around a pin 56 and between 
a pair of pins 58 in the cassette 21 to the take-up reel 18 in the 
cassette. 
The slave tape 12 extends from the supply reel 22 between a pair of pins 60 
in the slave cassette 28 and then on the end of a spring 62 in tensioning 
apparatus generally indicated at 64. The tensioning apparatus 64 is also 
referred to as "an articulator" in the subsequent discussion relating to 
the flow charts shown in FIGS. 29-35. The tensioning apparatus 64 may have 
a construction and operation corresponding to the construction and 
operation of the tensioning apparatus 32. In this way, the tensioning 
apparatus 64 compensates in the tension of the slave tape 12 for changes 
in tension resulting from eccentricities in the rotation of the supply 
reel 22. 
The slave tape 12 then extends over a pin 66 to a guide generally indicated 
at 68. The guide 68 corresponds in function and operation to the guide 44. 
The guide 68 regulates the tension of the slave tape 12 just before the 
slave tape reaches a heater generally indicated at 70. The heater may have 
a construction and operation such as disclosed and claimed in co-pending 
application Ser. No. 07/733,174. In this way, the tensions of the 
mirror-master tape 10 and the slave tape 12 are respectively regulated by 
the guides 44 and 68 so that the image on the slave tape 12 will conform 
to the image on the mirror-master tape 10 after the thermomagnetic layer 
on the slave tape has cooled to ambient temperatures. In effect, the guide 
44 compensates for the extra length imparted to the slave tape 12 by the 
stretching resulting from the heater 70. 
The heater 70 is disposed between the guide 68 and a capstan 72 in 
contiguous relationship to the guide and the capstan. The capstan 72 abuts 
the pinch roller 50 in one operative relationship of the pinch roller and 
the slave tape 12 extends over the capstan. The capstan 72 is driven by 
the motor 13. The capstan 72 and the pinch roller 50 accordingly press the 
slave tape 12 against the mirror-master tape 10 after the heater 70 has 
heated the thermomagnetic layer on the slave tape to a temperature above 
the Curie temperature of the thermomagnetic layer to destroy any image in 
the thermomagnetic layer. 
It will be appreciated that the capstan 72, the heater 70 and the guide 68 
can be interchanged with the guide 44 and the pinch roller 50 without 
departing from the scope of the invention. The claims in the application 
should accordingly be interpreted broadly to cover the possibility of such 
an interchange. 
The contact between the mirror-master tape 10 and the slave tape 12 causes 
the slave tape to be cooled below the Curie temperature and the image on 
the master tape 10 to be transferred to the thermomagnetic layer on the 
slave tape. The slave tape 12 then extends around a pin 76 at the end of a 
dancer arm 78 and around a pin 80 to a pin 82 in the cassette 28. The 
slave tape 12 extends from the pin 82 to the take-up reel 24. 
A controller 84 (which may be a microprocessor) in FIG. 1 controls the 
operation of the take-up motors 20 and 26 for the take-up reels 18 and 24, 
the drive motor 13 and the power source to the heater 70. The controller 
84 also controls the operation of an actuator 86 which moves the guide 44 
and the pinch roller 50 to a first position with the pinch roller abutting 
the capstan 72 and a second position with the pinch roller displaced from 
the capstan. In the first position of the pinch roller 50, the image on 
the mirror-master tape is transferred to the slave tape 12 when the pinch 
roller and the capstan 72 are rotated. In the second position of the pinch 
roller 50, the mirror-master tape 10 can be disposed on the pinch roller 
and the slave tape 12 can be disposed on the capstan 72. 
An infrared source 85 is in an aperture in the slave cassette 28. An 
infra-red detector 87 receives the light from the source 85 and produce a 
signal when substantially all of the image on the mirror-master tape 10 
has been transferred to the slave tape 12. This causes the pinch roller to 
be moved from the position (FIG. 14) abutting the capstan 72 to the 
position (FIG. 13) displaced from the capstan. In the displaced position 
of the pinch roller 50, the capstan 72 is immediately stopped by 
de-energizing the drive motor 13 (FIG. 1). An infrared detector 89 detects 
when the slave tape 12 is broken or when all of the slave tape has been 
transferred from the supply reel 22. An infrared source 89 and an 
infra-red detector 91 may be similarly provided for the master tape 10. An 
infrared detector 93 detects when the mirror-master tape 10 is broken or 
when all of the master tape has been transferred from the supply reel 16. 
The system shown in FIG. 1 and described above has certain important 
advantages. It provides for the transfer of the image on the mirror-master 
tape 10 in the cassette 21 to the slave tape 12 in the cassette 28. Since 
the image transfer is from the tape in the cassette 21 to the tape in the 
cassette 28, the system can be relatively small and simple. Furthermore, 
since the image on the mirror-master tape 10 is transferred to the slave 
tape 12 in the cassette 28, the image on the slave tape is ready for 
immediate display since the cassette is a video cassette reproducer (VCR) 
of standard construction. The system is also advantageous in regulating 
the tensions of the mirror-master and slave tapes during the transfer of 
the image on the master tape to the slave tape. This provides for the 
transfer of the image on the mirror-master tape with high fidelity to the 
slave tape. 
The system shown in FIG. 1 is disposed at a 0.degree. station where the 
image on the mirror-master tape 10 can be transferred to the slave tape 
12. In this station, all of the components shown in FIG. 1 are in a common 
plane. Stated differently, the master cassette 21 is perpendicular to the 
pinch roller 50 and the slave cassette 28 is perpendicular to the capstan 
72. Before the image on the mirror-master tape 10 can be transferred to 
the slave tape 12, the mirror-master tape 10 has to be disposed on the 
guide 44 and the pinch roller 50 and the slave tape 12 has to be disposed 
on the guide 68, the heater 70 and the capstan 72. This is accomplished 
with certain components shown in FIG. 1 in positions defining a 15.degree. 
station. In the 15.degree. station, certain of the components defining the 
path of the slave tape 12 in FIG. 1 may be considered as being tilted 
upwardly from the plane of the paper through a suitable angle such as 
approximately 15.degree. with the right end of the cassette 28 in FIG. 1 
as a fulcrum. Similarly, the components defining the path of the 
mirror-master tape 12 in FIG. 1 may be considered as being tilted upwardly 
from the plane of the paper through an angle such as approximately 
15.degree. with the fulcrum near the left end of the cassette 21 in FIG. 
1. 
The mirror-master tape 10 is initially disposed on a plate 90 (FIG. 2) at a 
suitable angle such as an angle of approximately 90.degree. to the flat 
surface shown in FIG. 1. This flat surface is common to the guide 44, the 
pinch roller 50, the guide 68, the heater 70 and the capstan 72, the 
mirror-master tape 10 and the slave tape 12 during the time that the image 
on the mirror-master tape 10 is being transferred to the slave tape 12. 
This flat surface may be considered to be a 0.degree. position or station. 
The position of the master cassette 21 at the 90.degree. position is 
illustrated schematically at 21a in FIG. 2 and the position of the master 
cassette 21 at the 0.degree. position is illustrated schematically at 21b 
in FIG. 2. 
Before the mirror-master tape 10 is transferred from the 90.degree. 
position or station 21a to the 0.degree. position or station 21b, it is 
transferred to a position or station 21c. The position of the station 21c 
is between the positions or stations 21a and 21b and is at a suitable 
angle such as 15.degree. relative to the 0.degree. position 21b. The 
plate 90 (FIGS. 2, 5 and 6) is initially disposed at the 15.degree. 
position 21c. The plate 90 holds a pair of threading arms 92 and 94 (FIGS. 
5 and 6) and the dancer arm 54. The threading arms 92 and 94 are 
respectively pivotable on pins as at 96 and 98 between retracted and 
extended positions. 
The pivoting of the threading arms 92 and 94 is synchronized by of meshing 
gears 100 and 102 (FIGS. 5 and 6) respectively disposed on the pins 96 and 
98. The pin 30 (also shown in FIG. 1) is disposed at the free end of the 
threading arm 92 and a pin 104 is disposed at the free end of the 
threading arm 94. As shown in FIGS. 5 and 6, the threading arm 94 engages 
a lug 106 on the dancer arm 54 to pivot the dancer arm from the retracted 
position shown in FIG. 5 to the extended position shown in FIG. 6 as the 
threading arm pivots from the retracted position shown in FIG. 5 to the 
extended position shown in FIG. 6. The dancer arm 54 is pivotable as at 
110 and is spring loaded as at 112 to return the dancer arm from the 
extended position shown in FIG. 6 to the retracted position shown in FIG. 
5 when the threading arms 92 and 94 return from the extended positions 
shown in FIG. 6 to the retracted positions shown in FIG. 5. 
In the position shown in FIG. 5, the pin 30 on the threading arm 92 and the 
pin 104 on the threading arm 94 engage the master tape while the master 
tape 10 is still entirely within the cassette 21. This is the 15.degree. 
position of the station discussed above and is indicated at 21c in FIG. 2. 
With the cassette 21 disposed on the plate 90 in the position of the 
station 21c (FIG. 2), the threading arms 92 and 94 are pivoted from the 
retracted positions shown in FIG. 5 to the extended positions shown in 
FIG. 6. When the threading arm 94 is pivoted to the position shown in FIG. 
6, the threading arm 94 engages the lug 106 and moves the dancer arm 54 to 
the position shown in FIG. 6 against the action of the helical spring 112. 
In the position shown in FIG. 6, the pins 30 and 104 respectively on the 
threader arms 92 and 94 dispose the master tape 10 outwardly from the 
master cassette 21. The pin 52 on the dancer arm 54 engages the 
mirror-master tape 10 tightly against the pin 104. The plate 90 is then 
moved from the station 21c (the 15.degree. position) to the station 21 
(the 0.degree. ) position in FIG. 2. 
At the station 21b shown in FIG. 2, the threading arms 92 and 94 are 
retracted from the extended position shown in FIG. 6 to the position shown 
in FIG. 5. As the threading arms 92 and 94 retract, the dancer arm 54 
retracts because of the action of the spring 112. As the threading arms 92 
and 94 retract from the position shown in FIG. 6 to the position shown in 
FIG. 5, the articulator 32 pivots on the pin 42 from the position shown in 
FIGS. 5 and 6 to the position shown in FIG. 1 so that the mirror-master 
tape 10 becomes disposed on the spring arm 34 at the end of the spring 
arm. This causes the mirror-master tape 10 to become disposed on the 
spring arm 34, the guide 44 and the pinch roller 50 as shown in FIG. 1. 
The slave tape 12 receives a sequence of operations similar to that shown 
in FIGS. 1, 2, 5 and 6 for the master tape 10 and described above. The 
slave cassette 28 has different stations corresponding to the different 
stations for the master tape. Specifically, a plurality of slave cassettes 
28 are disposed in a stacked relationship in a station generally indicated 
at 120 at FIG. 2. The forward cassette in the station 120 is designated as 
28a to indicate its correspondence to the station 21a for the master 
cassette. 
The slave cassettes 28 are retained in the station 120 as by a leaf spring 
123 (FIGS. 2, 2A and 2B) wound in a helical configuration at one end on a 
pin 286. The helical portion of the leaf spring 123 is confined within a 
pair of spaced walls 124. A backing member 125 attached to the spaced 
walls 124 also tends to confine the helical portion of the leaf spring 
123. The leaf spring 123 urges the cassettes forwardly in the station. 
The leaf spring is attached to a post 127 at the forward end of the station 
120. A ramp 129 pivotable as at 131 abuts the forward periphery of the 
forward one of the cassettes in the station 120. The ramp 129 is biased 
upwardly by a compressed spring 133. The ramp 129 is depressed by a 
pivotal movement on the pin 131 against the action of the spring 133 when 
additional ones of the slave cassettes 28 are loaded into the station 120 
from the forward end of the cassette. 
The forward cassette 28a in the station 120 is pivoted through an arc 
indicated in broken lines at 122 (FIG. 2) to a position or station 28c 
corresponding to the station 21c for the master cassette. It will be 
appreciated that this pivotal movement is through an angle such as 
165.degree. for the slave cassette 28 as distinguished from a pivotal 
movement of the master cassette 10 through an angle such as approximately 
75.degree.. At the position or station 28c, an initial threading operation 
is provided corresponding to the initial threading provided on the 
cassette 21 at the station 21c. In other words, the slave tape 12 is moved 
from the position inside the cassette 28 to a position above the guide 68, 
the heater 70 and the capstan 72 with the pinch roller 50 displaced from 
the capstan. 
The slave cassette 28a is then pivoted to the position 28b corresponding to 
the position shown at 21b for the master tape 10. The pivoting occurs 
through an arc indicated schematically at 122 in FIG. 2. At this station, 
the master cassette 21 is perpendicular to the pinch roller 50 and the 
slave cassette 28 is perpendicular to the capstan 72. After the image on 
the mirror-master tape 10 has been transferred to the slave tape 12 at the 
position 28b, the slave cassette 28a is transferred to a position or 
station 28c and the slave tape 12 is removed from the guide 68, the heater 
70 and the capstan 72 and causes the slave tape 12 to be returned to a 
disposition entirely within the cassette 28. The slave cassette is then 
transferred into a station generally indicated at 250 in FIG. 2. 
As will be seen in FIG. 3, the slave cassette 28 has a groove 130. This 
groove is disposed at a forward periphery of each of the slave cassettes 
28 in the station 120. As shown in FIG. 3, a spring clip 132 is disposed 
in the groove 130 in the forward one of the cassettes 28 in the station 
120. A retaining pin 134 extends into the groove 130 in the forward 
periphery of the next one of the slave cassettes 28 in the station 120 and 
grips the rear periphery of the forward one of the cassettes. The spring 
clip 132 and the retaining pin 134 retain the forward one of the slave 
cassettes as the slave cassette is pivoted to the different positions or 
stations shown in FIG. 2. Although only one spring clip 132 and one 
retaining pin 134 are shown in FIG. 3, two (2) spring clips 132 and two 
(2) retaining pins 134 are actually provided (FIG. 15) to grip the forward 
one of the slave cassettes 28 at different heights on the slave cassette. 
This will be described in detail subsequently. 
When the slave cassette 28 is in the position or station 28c, it engages a 
plate 136 (FIGS. 7 and 8) corresponding to the plate 90 (FIG. 8b) for the 
mirror-master tape. The plate 136 contains threading arms 138 and 140 
respectively corresponding to the threading arms 92 and 94 for the master 
tape 10. The threading arms 138 and 140 are respectively pivotable on pins 
142 and 144. Pins 146 and 148 are respectively provided at the ends of the 
threading arms 138 and 140. The pins 146 and 148 engage the slave tape 12 
inside the slave cassette 28 in the retracted position of the threading 
arms shown in FIG. 7. The threading arms 138 and 140 are pivoted 
synchronously as by meshing gears 150 and 152 driven by a motor 154. 
The plate 136 also contains the dancer arm 78. The threading arm 140 
engages a lug 156 on the dancer arm 78 to drive the dancer arm from the 
position shown in FIG. 7 to the position shown in FIG. 8 as the threading 
arm is pivoted by the motor 154 from the position shown in FIG. 7 to the 
position shown in FIG. 8. The dancer arm 78 is pivotable on a pin 158 at 
one end of the threading arm. A suitable constrainable member such as a 
helical spring 160 becomes constrained when the dancer arm 78 becomes 
pivoted from the position shown in FIG. 7 to the position shown in FIG. 8. 
The constrained spring 160 returns the dancer arm 78 to the position shown 
in FIG. 7 when the motor 154 returns the threading arms 138 and 140 to the 
positions shown in FIG. 7 from the positions shown in FIG. 8. 
The threading arms 138 and 140 and the dancer arm 78 are in the positions 
shown in FIG. 7 when the slave cassette 28 reaches the position 28c after 
being withdrawn from the station 120 and pivoted from the position or 
station 28a to the position or station 28c. The position or station 28c 
corresponds to the 15.degree. position or station of the slave cassette. 
At this station, the threading arms 138 and 140 are rotated from the 
position shown in FIG. 7 to the position shown in FIG. 8. The threading 
arm 140 in turn drives the dancer arm 78 from the position shown in FIG. 7 
to the position shown in FIG. 8. FIG. 8A shows the slave tape 12 partially 
extended in the 15.degree. position or station. FIG. 8B shows the slave 
tape 12 in the fully extended position. 
In the position shown in FIG. 8, the slave tape 12 is disposed over guide 
68, the heater 70 and the capstan 72. The plate 136 is moved to the 
station 28b (the 0.degree. position) for the slave tape 12 after the tape 
has been extended to the position shown in FIG. 8. At this station, the 
threading arms 138 and 140 are retracted to the position shown in FIG. 7. 
This causes the dancer arm 78 to be retracted to the position shown in 
FIG. 7. In these positions of the threading arms 138 and 140 and the 
dancer arm 78, the slave tape 10 has the path shown in FIG. 1 with the 
slave tape being disposed on the guide 68, the heater 70 and the capstan 
72. At the same time that the threading arms 138 and 140 and the dancer 
arm 78 are retracted to the positions shown in FIGS. 1 and 7, the 
articulator 64 is moved from the position shown in FIGS. 7 and 8 to the 
position shown in FIG. 1. 
The slave cassette 28 is pivoted to the different positions shown in FIG. 3 
as by an arm 160 pivotable on a pin 162. The arm 160 is shown in FIG. 3 in 
a first position 160a corresponding to the position or station 28a for the 
slave cassette 28 and in a position 160c corresponding to the position or 
station 28c for the slave cassette. As will be seen in Figures subsequent 
to FIGS. 7 and 8, the arm 160 is mechanically coupled to an arm which 
drives the spring clip 132 with the arm 160 to rotate the slave cassette 
28 from the position or station 28a to the position or station 28c. 
A roller 164 (FIGS. 3 and 4) is disposed against the back side of the plate 
136. The roller 164 is disposed at the end of an arm 166 pivotable at its 
opposite end on a pin 168. A constrainable member such as a helical spring 
170 is disposed on the pin 168 so as to become constrained as the plate 
136 is moved from the 15.degree. position (shown in solid lines in FIG. 4) 
to the 0.degree. position (shown in broken lines in FIG. 4). As the spring 
170 becomes constrained, it exerts a force against the plate 136 to 
provide a controlled movement of the plate 136 to the 0.degree. position. 
In the 0.degree. position, the image on the mirror-master tape 10 is 
transferred to the slave tape 12. After the image on the mirror-master 
tape 10 has been transferred to the slave tape 12 and the plate 136 is 
returned to the 15.degree. position (the position or station 28c) for the 
slave cassette 28, the spring 170 operates to move the plate 136 to the 
15.degree. position. 
As shown in FIG. 11, the slave cassette 28 has a socket 172 concentric with 
the supply reel 22 and a socket 174 concentric with the take-up reel 24. 
Each of the sockets 172 and 174 is splined respectively to receive mating 
cylinders 176 and 178 on the plate 136 in the 15.degree. position of the 
plate. The mating cylinder 178 is driven by the take-up motor 26 in FIG. 1 
when the plate 136 is pivoted to the 0.degree. position (the position 28b 
of the slave cassette 28) in FIGS. 2, 3 and 4. 
After the image on the mirror-master tape 10 has been transferred to the 
slave tape, the threading arms 138 and 140 and the dancer arm 78 (FIGS. 1, 
7 and 8) are pivoted from the retracted position shown in FIG. 7 to the 
extended position shown in FIG. 8. This causes the slave tape 12 to become 
displaced from the guide 68, the heater 70 and the capstan 72. The plate 
136, the threading arms 138 and 140 and the dancer arm 78 are then moved 
with the slave cassette 28 to the 15.degree. position or station. The 
threading arms 138 and 140 and the dancer arm 78 are then moved from the 
extended position shown in FIG. 8 to the retracted position shown in FIG. 
7. In this relationship, the slave tape 12 becomes released from the 
threading arms 138 and 140 and the dancer arm 78 and becomes disposed 
entirely in the slave cassette 28 as shown in FIG. 7. 
As previously described, the slave cassettes 28 are initially located in a 
supply station 120 (indicated by the slave cassette 28a in FIG. 2) and are 
moved to the 15.degree. station indicated schematically at 28c in FIG. 2. 
The rotation is provided by a gear 180 (FIG. 17) which drives a bevel gear 
182 mounted on a support member 195. The bevel gear 182 in turn drives a 
shaft 184 on which is mounted the arms holding the spring clips 132 (also 
shown in FIG. 3). As previously described, the spring clips 132 are seated 
in the groove 130 (FIG. 3) at the forwardly facing periphery of the 
forward one of the slave cassettes 28 in the station 120. Each of the arms 
holding the spring clips 132 is formed by a block 186 (FIG. 17A) to which 
is attached as by bolts 187 a plate 188 holding one of the spring clips 
132. A slot 190 is provided in the block 186 at a position adjacent the 
plate 188. 
A bracket 192 (FIG. 17A) is disposed on a bearing 194 which is mounted on 
the shaft 184. The bracket 192 is attached as by bolts 196 to the plate 
136. A bracket 193 (FIG. 15) is mounted on a support member 195 and is 
provided with a lug 197 which overhangs the plate 136 and prevents the 
plate from moving past the 15.degree. station (the position 28c of the 
slave cassette 28 in FIG. 2) toward the 180.degree. position (the position 
28a of the slave cassette 28 in FIG. 2). This causes the plate 136 to be 
movable only between the 15.degree. position (the position 28c of the 
slave cassette 28 in FIGS. 2 and 3) and the 0.degree. position (the 
position 28b of the slave cassette 28 in FIG. 2). 
A pair of clevises generally indicated at 198 (FIGS. 15, 16, 17 and 17A), 
each defined by two (2) spaced discs, 199 with a groove 200 between the 
discs is also mounted on the shaft 184. A tyne 202 extends vertically from 
one of the discs in each clevis 198 into the slot 190 in the block 186 to 
move the block and the plate 188 rotationally with the clevis. Forked 
members 204 are disposed in the grooves 200 in the clevises 198 with the 
legs of each fork enveloping the associated groove. The forked members 204 
are mounted on rods 206 each of which is movable vertically in accordance 
with the rotary movements of a crank 208 (FIGS. 15 and 17). The crank 208 
is mounted on the support member 195. As may be seen in FIGS. 15 and 17, 
the crank 208 has a pair of pins 212 one of which engages the upper one of 
the rods 206 and the other one of which engages the lower one of the rods. 
The crank 208 is rotatable on a pin 214. Each of the rods 206 has a button 
215 (FIG. 17A) which moves on the support member 195 (FIGS. 15 and 17A) in 
accordance with the rotation of the crank 208. The crank 208 is driven by 
a motor 217 in FIG. 16. 
Each of the clevises 198 is attached as by bolts 216 (FIG. 17A) to a 
support member 218. The support member 218 has a socket 220 which receives 
the clevis 198. The support member 218 also has a socket 222 which 
receives one of the pins 134 (also shown in FIG. 3). The pin 134 is 
fixedly positioned relative to the support member 218 as by a set screw 
226. Each of the pins 134 has a finger 228 which is disposed in the groove 
130 (FIG. 3) in the forward periphery of the next one of the slave 
cassettes 28 in the station 120. The finger 228 may be tapered. The finger 
228 engages the rearward periphery of the forward one of the slave 
cassettes 28 in the station 120. Support members 230 (FIG. 17A) are 
disposed at the top and bottom of the shaft 184 and are suitably attached 
as by bolts 232 to the support member 195. The shaft 184 extends through a 
hole 234 in each of the support members 230. A bearing 236 is disposed 
between the shaft 184 and each of the support members 230. 
When the crank 208 is rotated in a counterclockwise direction on the pin 
214 as shown by the arrows in FIG. 17, one of the pins 212 on the crank in 
FIG. 17 drives the upper rod 206 downwardly and the other pin 212 on the 
crank drives the lower rod 206 upwardly. The upper one of the forked 
members 204 (FIG. 17A) moves downwardly with the associated rod 206 and 
drives the upper clevis 198 downwardly. This causes the finger 228 on the 
associated one of the pins 134 to become disposed in the top of the groove 
130 in the next one of the slave cassettes 28 in the supply station 120 
and to grip the forward one of the slave cassettes at the rear periphery 
of the slave cassette. 
In like manner, the lower one of the forked members 204 moves upwardly with 
the associated rod 206 and drives the lower clevis 198 upwardly. This 
causes the associated finger 228 on the associated one of the pins 134 to 
become disposed in the bottom of the groove 130 in the next one of the 
slave cassettes 28 in the supply station 120 and to grip the forward one 
of the slave cassettes at the rear periphery of this slave cassette. Since 
the forward periphery of the forward one of the slave cassettes 28 in the 
supply station 120 is also gripped at its upper and lower positions by the 
spring clips 132 (FIG. 3), the forward one of the slave cassettes 28 is 
firmly held at its forward and rear peripheries and is able to be pivoted 
from the supply station 120 (the 180.degree. position) to the position 28c 
(the 15.degree. position) in FIGS. 2 and 3 and the position 28b (the 
0.degree. position) in FIGS. 2 and 3. 
Each of the slave cassettes 28 has a spring loaded cover 230 (FIGS. 18-20) 
which is disposed over the slave tape 12 in the cassette. The 
spring-loaded cover 230 is conventional in tape cassettes now on the 
market. As the slave cassette 28 moves from the supply station 120 (the 
180.degree. position) toward the threading station (the 15.degree. 
position), the spring loaded cover 230 becomes opened by the mechanism 
shown in FIGS. 18-20. The opening of the cover 230 is initiated by the 
depression of a button 232 on the top peripheral surface of the slave 
cassette 28. A lug 234 on a bracket 236 depresses the button 232 as the 
slave cassette 28 swings past the lug. The bracket 236 is supported as by 
bolts 238 on the support member 195. 
As the slave cassette 28 continues to move toward the 0.degree. position, a 
pawl 240 at the end of an arm 242 engages the cover 230 and opens the 
cover to expose the slave tape 12. The arm 240 is pivotable as at 244 on 
the bracket 236. The pawl 240 is tapered as at 246. The pivotable 
relationship of the arm 242 and the taper 246 at the bottom of the pawl 
240 causes the pawl to ride upwardly as the slave cassette 28 moves toward 
the 15.degree. position or station, thereby providing for the continued 
movement of the slave cassette 28 toward the 15.degree. position. When the 
slave cassette 28 reaches the 15.degree. position or station, a pin 248 at 
the bottom of the plate 136 holds the cover 230 open to provide for the 
disposition of the slave tape on the capstan 72, the heater 70 and the 
guide 68 and the subsequent transfer of the image on the master tape 10 to 
the slave tape 12. 
After the image on the master tape 10 has been transferred to the slave 
tape 12, the slave cassette 28 holding the slave tape 12 is transferred 
from the 0.degree. station to the 15.degree. station. At the 15.degree. 
position, the threading arms 138 and 140 and the dancer arm 78 are 
retracted to the position shown in FIG. 7. The slave cassette is then 
pivoted to a receiving station generally indicated at 250 in FIGS. 21-28. 
The receiving station 250 is disposed at a 90.degree. position relative to 
the supply station 120 at the 180.degree. position and the image transfer 
station at the 0.degree. position. 
At the receiving station 250, the slave cassette 28 is transferred between 
a pair of belts 252 (FIGS. 21 and 23) movable in the 90.degree. direction. 
The belts are initially displaced by a distance greater than the height of 
the slave cassette 28 so that the slave cassette 28 can be easily disposed 
between the belts. The belts 250 are disposed on a pair of spaced pulleys 
254 (FIG. 23) so that the belts can be rotatable in a closed loop in the 
90.degree. direction. The pulleys 254 are in turn disposed within a pair 
of pulleys 256, one of the pulleys in each pair driving the other as by a 
belt 258. 
A motor 260 (FIG. 23) drives one of the pulleys 256 in the upper pair. A 
pulley 262 is rotatable with the other pulley 256 in the upper pair. The 
pulley 262 drives an endless belt 264 which in turn drives a pulley 266. 
Gears 268 and 270 are in turn driven by the pulley 266. The gear 270 is 
coupled to one of the pulleys 256 in the lower pair. With the belts 252 
disposed as shown in FIG. 23, the distance between the belts 252 is 
greater than the height of the slave cassette 28 to facilitate the 
transfer of the slave cassette to the position between the belts for 
transport by the belts. 
After the slave cassette 28 has been transferred between the belts 250, a 
solenoid 272 in FIG. 21 is energized. This causes an arm 274 mounted 
concentrically on the solenoid to rotate in a counterclockwise direction 
in FIG. 21. At its free end, the arm 274 has a roller 276 which engages a 
shelf 278 on which the pulley 266 is mounted. The pivotal movement of the 
arm 274 in the counterclockwise direction causes the shelf 278 to rise so 
that the lower one of the belts 252 engages the bottom surface of the 
slave cassette 28. 
The lowered position of the bottom belt 252 is shown in solid lines in FIG. 
21 and the raised position of the belt is shown in broken lines in FIG. 
21. The raised position of the bottom belt 252 is shown in solid lines in 
FIG. 22. When the belt is raised to the position shown in FIG. 22, the 
belt 264 becomes tilted because the gears 268 and 270 change from the 
vertical relationship shown in FIG. 23 to the skewed relationship shown in 
FIG. 22. 
After the lower belt 252 has become raised to the position shown in FIG. 
22, the support members 218 (FIG. 17A) are moved vertically so that the 
distance between the upper and lower fingers 228 is increased. This causes 
the fingers 228 to be removed from the rear peripheral surface of the 
slave cassette 28. Even though the fingers 228 become removed from the 
rear peripheral surface of the slave cassette 28, the slave cassette is 
retained firmly in position between the belts 252 in FIG. 23. The slave 
cassette 28 is then rotated through a relatively small angle such as a few 
degrees (e.g. 4.degree.) toward the 0.degree. position by the rotation of 
the gears 180 and 182 (FIG. 16). This allows the spring clips 132 to slip 
out of the grooves 130 in the slave cassette 28 so that the slave cassette 
28 is retained only by the belts 252. 
After the slave cassette 28 has been transferred to the belts 252 by 
raising the lower one of the belts, the motor 260 (FIG. 23) is operated to 
move the belts in a direction (see the arrow 281 in FIG. 25) for 
transferring the slave cassette to a platform 280 (FIG. 21) laterally 
displaced from a compartment 282 (FIG. 27) included in the station. As 
shown in FIG. 27, the slave cassettes 28 having a copy of the image from 
the mirror-master tape 10 are disposed in a stacked relationship in the 
compartment 282. 
The mechanism for transferring the slave cassette 28 into the compartment 
282 is shown primarily in FIGS. 21 and 24-28. The mechanism includes a 
motor 300 (FIG. 24) which drives a gear 302 (FIG. 21). The gear 302 is in 
mesh with a bevel gear 304 which drives a gear train generally indicated 
at 306 (FIGS. 21 and 24). A disc 308 (FIG. 24) is driven by one of the 
gears in the gear train 306 and a member 310 in the form of a segment of a 
cylinder is driven by another one of the gears in the gear train 306. A 
drive pin 312 is disposed on the periphery of the disc 308 and a drive pin 
314 is disposed on the periphery of the disc segment 310. A disc 316 (FIG. 
28) is disposed on the same shaft as the disc 308 to sense the light from 
a source 318 schematically shown in FIG. 25. The sensing is provided to 
insure that the drive pin 312 is in proper rotary position when the slave 
cassette 28 is transferred into the compartment 282. 
When the slave cassette 28 has been transferred to the compartment 282, the 
bottom belt 252 (FIG. 23) is lowered. This is partly to position the 
bottom belt 252 so that the pin 314 (FIG. 24) can be moved by the drive 
pins 310 into the compartment 282. The rotation of the drive pins 312 and 
314 is shown by arrows in FIG. 25. As will be seen in FIG. 25, the 
rotation of the disc segment 310 is in a clockwise direction and the 
rotation of the disc 308 is in a counterclockwise direction. 
When the slave cassette 28 reaches the platform 280, the drive pins 312 and 
314 are substantially in the positions shown in FIG. 25. The drive pins 
312 and 314 are then rotated to the positions shown in FIG. 26. In these 
positions, the drive pins 312 and 314 engage the rear peripheral surface 
of the slave cassette 28 at the opposite ends of this peripheral surface. 
As the drive pins 312 and 314 continue to rotate from the position shown 
in FIG. 26 to the position shown in FIG. 27, they drive the slave cassette 
28 from the platform 280 into the compartment 282 through a mouth 318 
through a mouth 319 in the compartment. As will be seen in FIGS. 24 and 
25, the mouth 319 of the compartment 318 is substantially parallel to, but 
displaced from the belts in the direction of movement of the belts. In 
this way, the belts 252 initially displace the slave cassettes in a 
direction parallel to the mouth 319 of the compartment 282 and, after the 
slave cassettes have been transferred to the mouth of the cassette, the 
slave cassettes are transferred through the mouth into the compartment. 
It will be appreciated that the drive pins 310 and 312 align the slave 
cassette 28 before they drive the slave cassette 28 into the compartment 
282. For example, if the slave cassette 28 is skewed to the left as shown 
in solid lines at 28f in FIG. 25, the drive pin 314 will engage the 
forward peripheral surface of the slave cassette 28 and will reposition 
the cassette to an aligned relationship before it reaches the rear 
peripheral surface of the slave cassette as shown in that Figure. 
Similarly, if the position of the slave cassette 28 is skewed to the right 
as indicated schematically in broken lines at 28g in FIG. 25, the drive 
pin 314 will engage the forward surface of the slave cassette as it moves 
from the position shown in FIG. 25 to the position shown in FIG. 26. As 
the drive pin 314 continues to move toward the position shown in FIG. 26, 
it will align the slave cassette so as to be able to clear the slave 
cassette and reach the position shown in FIG. 26. 
The apparatus shown in the drawings and described above may include several 
doors for purposes of safety. For example, the apparatus may include a 
door 330 (FIG. 2) pivotable as at 332 for preventing access in the closed 
position to the master cassette 21 in the 0.degree. and 15.degree. 
positions of the master cassette and for providing access in the open 
position to load the master cassette into the apparatus. The apparatus may 
also include a front door 334 (FIG. 2) pivotable as at 336. In the closed 
position, the door 334 prevents access to the components shown in FIG. 1 
including the pinch roller 50 and the capstan and the threading arms. In 
the open position, the door 334 provides access to these components. Only 
a portion of the door 334 is shown in FIG. 2. 
The apparatus may include a slidable door 342 (FIG. 12). The slidable door 
342 may be operated by a motor 344 (FIG. 2) and by a rack and pinion 
arrangement 346. The door 342 is slidable to a closed position preventing 
the forward one of the slave cassettes in the station 120 from being 
transferred to the 15.degree. and 0.degree. positions. A door 350 (FIG. 
10) is disposed at the front end of the supply station 120. In the open 
position, the door 350 provides for the insertion of additional ones of 
the slave cassettes 28 into the supply station 120. In the closed 
position, the door 350 prevents such insertion. 
FIG. 29 provides a flow chart showing a subroutine for positioning the 
master tape 10 to provide an image on the slave tape 12 in the forward one 
of the slave cassettes 28 after such slave cassette has been transferred 
to the 0.degree. position or station. As shown in FIG. 29, the subroutine 
for loading the mirror-master tape 10 and determining its length is 
selected in the software by selecting the proper "Call" subroutine in the 
software. 
As indicated in the flow chart in FIG. 29, a first step in the subroutine 
is to determine if the master tape 10 has been provided at the position 
21a in FIG. 2. A determination is then made as to whether the magazine 
door 330 on the master side is closed. This door is to prevent access to 
the master cassette 21 from an external position when the master tape is 
in an operative position. If the door 330 is not closed, an error is 
indicated in one of the lights 338 on the panel 340 and the subroutine is 
prevented from continuing. If the door 330 is closed, the master cassette 
21 is pivoted to the 15.degree. position or station. 
The mirror-master tape 10 is then wound so that substantially all of the 
tape is on the take-up reel 18 (FIG. 1) and the mirror-master tape 10 is 
at the beginning of the image or movie. The mirror-master tape 10 is 
thereafter wound on the supply reel 16 to the end of the tape as sensed by 
infrared sensor 91. The mirror-master tape 10 is then disposed on the 
pinch roller 50 at the 0.degree. station and the pinch roller is moved at 
the 0.degree. station into abutting relationship with the capstan 72. The 
mirror-master tape 10 is then rewound on the take-up reel 18 until the 
beginning of tape is sensed by infrared sensor 93. 
As part of the factory calibration of the tape drive system, the diameter 
of the capstan 72 is measured to a high accuracy. This capstan diameter 
measurement is made as follows: A known-length calibration tape is run 
from end to end with the pinch roller 50 and the capstan 72 in abutting 
relationship. The rotation angle of the capstan 72 is measured by counting 
pulses from a code wheel attached to the capstan as the calibration tape 
is run from end to end. Since the length of the calibration tape is known 
and the measurement of the rotation angle of the capstan is inherently 
accurate, the diameter of the capstan can be calculated with high 
accuracy. This calculated capstan diameter is stored in computer memory 
for subsequent measurements of the lengths of mirror-master tapes. 
During the rewinding of the mirror-master tape 10 on the take-up reel 18 at 
the 0.degree. station with the pinch roller 50 and the capstan 72 in 
abutting relationship, the length of the image on the mirror-master tape 
10 is determined. The mirror-master tape is run from one end to the other. 
The length of the mirror-master tape is determined relatively precisely 
during this run because the capstan 72 is well coupled to the 
mirror-master tape 10 by a force of the abutting pinch roller 50 at the 
0.degree. station and because the diameter and total rotation angle of the 
capstan are known with high accuracy. The location of the image on the 
mirror-master tape is located accurately by specifying that the beginning 
and end of the image be placed at a specific distance from the beginning 
and end of the master-tape. A return is then made to the software to 
obtain a selection in the software of the next subroutine to be performed. 
FIG. 30 illustrates a simplified flow chart of a subroutine for indicating 
the steps in preparing the mirror-master tape 10 to rewind the 
mirror-master tape. As a first step, the mirror-master tape is unthreaded. 
This includes the steps of moving the plate 90 to the 15.degree. position 
and retracting the threading arms 92 and 94 and the dancer arm to the 
position shown in FIG. 5. The mirror-master tape 10 is then rewound on the 
take-up reel 18 at the 15.degree. station to the position that constitutes 
the beginning of the tape (actually the end of the image or movie) on the 
mirror-master tape. The mirror-master tape 10 is thereafter rethreaded 
over the guide 44 and the pinch roller 50, and the mirror-master tape is 
returned to the 0.degree. position ready to transfer the image again to 
another slave tape 12. 
Although the subroutine shown in FIG. 30 and described above is 
satisfactory at the 15.degree. station, it will be appreciated that the 
subroutine may also be accomplished with the mirror-master tape 10 in the 
0.degree. position. This eliminates any necessity of transferring the 
master cassette 21 from the 0.degree. position to the 15.degree. position 
before the subroutine shown in FIG. 30 and described above is performed. 
FIG. 31 illustrates the flow chart for the subroutine of threading and 
unthreading the slave tape 12. As a first step, a determination is made as 
to whether the pinch roller 50 is open, in other words, whether the pinch 
roller is displaced from the capstan 72. If the pinch roller 50 is not 
open, it is opened. If the pinch roller 50 is open and a threading 
operation is being performed on the slave tape 12, the threading arms 138 
and 140 and the dancer arm 78 are extended at the 15.degree. position of 
the slave cassette 28 from the position shown in FIG. 7 to the position 
shown in FIG. 8. 
In the threading operation, the sliding door 342 (FIG. 12) is closed to 
optionally allow additional slave cossettes 28 to be loaded into station 
120. The plate 136 (FIGS. 2, 7 and 8) is then moved to the 0.degree. 
position and a determination is made as to whether there is any angular 
error in the positioning of the plate. If there is no error in such 
positioning, the operation of the motor for the sliding door 342 is 
interrupted. 
The threading arms 138 and 140 and the dancer arm 78 are then retracted 
from the position shown in FIG. 8 to the position shown in FIG. 7. If 
there is no error in such retraction, the articulator 64 is moved from the 
position shown in FIGS. 7 and 8 to the operative position shown in FIG. 1; 
the door 350 (FIG. 10) for the supply station 120 is unlocked; and a light 
is illuminated to indicate that this is a proper time for optionally 
loading additional ones of the slave cassettes 28 into the supply station 
120. 
If an unthreading operation is being performed, the articulator 64 for the 
slave tape 12 is initially moved from the operative position shown in FIG. 
1 to the extended position shown in FIGS. 7 and 8 to prevent the 
articulator from interfering with the threading operation. If there is no 
error in such movement, the threading arms 138 and 140 and the dancer arm 
78 are extended from the position shown in FIG. 7 to the position shown in 
FIG. 8. If there is no error in such extension, the sliding door 342 (FIG. 
12) is opened. The door 350 (FIG. 10) for the supply station 120 is then 
locked in the closed position. This prevents additional ones of the slave 
cassettes 28 from being inserted into the supply station 120. The lamp 
indicating the propriety of inserting the additional ones of the slave 
cassettes 28 into the supply station 120 is also turned off. 
The plate 136 (FIGS. 2, 7 and 8) is then moved from the 0.degree. position 
or station to the 15.degree. position or station. If there is no error in 
this positioning, the operation of the motor 344 (FIG. 2) for moving the 
sliding door 342 (FIG. 12) is discontinued. The threading arms 138 and 140 
and the dancer arm 78 are then moved from the extended position shown in 
FIG. 8 to the retracted position shown in FIG. 7. This completes the 
subroutine if there is no error. A different subroutine can then be 
selected. 
FIG. 32 shows the flow chart for a subroutine for transferring the slave 
cassettes 28 to the 0.degree. station and transferring the image on the 
master tape 10 to the slave tape 12 at the 0.degree. station. As a first 
step in this subroutine, a determination is made as to whether the door 
350 (FIG. 10) to the supply station 120 is open. If the door 350 is not 
open, the mechanism for gripping and transporting the slave cassettes 28 
is operated to move the mechanism to the 180.degree. position where the 
supply station 120 is located. This mechanism is shown in FIG. 15-17A. 
If the mechanism is properly positioned at the 180.degree. station, the 
forward one of the slave cassettes 28 in the supply station is gripped by 
the mechanism shown in FIGS. 15-17A. This slave cassette is moved to the 
0.degree. position or station if there is no error in the gripping of this 
slave cassette. If the slave cassette is properly positioned at the 
0.degree. position, the slave tape is mounted at the 0.degree. position 
and rewound to the zero position (so that all of the tape is on the supply 
reel 22). The slave tape 12 is then rewound on the tape-up reel 24 through 
a distance corresponding to the length of the image on the master tape 10. 
The slave tape 12 is now in a position to be rewound on the supply reel 16 
while the image on the master tape 10 is transferred to the slave tape. 
The slave tape is then moved to the 15.degree. position. 
If there is no error in the steps described in the previous paragraph, a 
determination is made as to whether the mirror-master tape 10 is rewound 
to the position for transferring the image on the mirror-master tape to 
the slave tape. If the master tape 10 has been properly rewound to the 
desired position, the threading arms 138 and 140 and the dancer arm 78 are 
extended from the position shown in FIG. 7 to the position shown in FIG. 
8; the slave cassette 28, the threading arms 138 and 140 and the dancer 
arm 78 are moved to the 0.degree. position; and the threading and dancer 
arms are retracted at the 0.degree. position to dispose the slave tape on 
the guide 68, the heater 70 and the capstan 72. If there is no error in 
these steps, the subroutine shown in FIG. 32 is completed as indicated by 
the "Return" block in FIG. 32. 
FIG. 33 is a flow chart of a subroutine for transferring the image on the 
mirror-master tape 10 to the slave tape 12. As a first step in the 
subroutine, a determination is made as to whether the master cassette 21 
is in place. If the master cassette 21 is not in place, the master 
cassette is loaded into the apparatus and the master tape 10 is disposed 
on the pinch roller 50 at the 0.degree. position or station. A 
determination is then made as to whether the supply station 120 is empty 
of slave cassettes 28. If the supply station 120 is empty of slave 
cassettes 28, an indication to this effect is provided. If the supply 
station 120 is not empty but the supply of the slave cassettes in the 
station is low, a display warning to this effect is provided so that the 
slave cassettes in the supply station can be replenished. 
As long as there are slave cassettes 28 in the supply station 120, the 
forward one of the slave cassettes in the supply station 120 is 
transferred to the 15.degree. position or station to receive the threader 
arms 138 and 140 and the dancer arm 78 (FIGS. 1, 7 and 8) and then to the 
0.degree. position or station. The slave tape in such cassette is then 
disposed on the guide 68, the heater 70 and the capstan 72. The pinch 
roller 50 is then moved to the closed position abutting the capstan 72 and 
the drive motor 13 (FIG. 1) for the capstan 72 is operated. 
The heater 70 is energized. If there is no error in energizing the heater 
70, the image on the master tape 10 is transferred to the slave tape 12. 
At the end of this image transfer or in the event of a heater or tape 
error, the heater 70 is turned off and the pinch roller 50 is moved from 
the position (FIG. 14) abutting the capstan 72 to the position (FIG. 13) 
displaced from the capstan. The rotation of the capstan 72 is 
discontinued. The motor 20 (FIG. 1) for the mirror-master tape 10 and the 
motor 26 for the slave tape 12 are de-energized. The mirror-master tape 10 
is then rewound on the take-up reel 24 to the position (the end of the 
image or movie) for initiating a transfer to a slave cassette 28. 
Concurrent with rewinding the mirror-master tape 10, the slave cassette 28 
is transferred to the receiving station 250. 
If there are slave cassettes 28 remaining in the supply station 120, the 
sequence is returned to the position designated as "A" in FIG. 33 to 
initiate the steps of transferring the image on the mirror-master tape 10 
to the tape 12 in the forward one of the slave cassettes 28 in the slave 
station 120. If the specified number of slave cassettes 28 have been 
coupled, the door 350 (FIG. 10) at the front of the supply 120 is unlocked 
and the light indicating the opportunity to insert additional ones of the 
slave cassettes 28 into the supply station 120 is illuminated. Additional 
ones of the slave cassettes 28 are then inserted into the supply station. 
FIG. 34 shows a flow chart of a subroutine for transferring one of the 
slave cassettes 28 to the receiving station 250 after the image on the 
mirror-master tape 10 has been transferred to the slave tape 12 in such 
cassette. The slave tape 12 is unthreaded from the guide 68, the door 350 
(FIG. 10) at the front of the supply station 120 is locked and the light 
indicating the opportunity to load additional ones of the slave cassettes 
into the supply station is turned off, as part of the unthread tape 
routine, and the slave tape is moved to the receiving station 250. 
FIG. 35 shows a flow chart of a relatively detailed subroutine for 
transferring one of the slave cassettes 28 into the receiving station 250 
after the image on the mirror-master tape 10 has been transferred to the 
slave tape 12 in such cassette. The slave cassette 28 is initially rotated 
from the 15.degree. station to the station 250, which is at 90.degree. 
relative to the supply station 120 and to the 0.degree. station. A 
determination is then made as to whether the compartment 282 (the output 
bin) is full. If the compartment 282 is full, an indication to this effect 
is provided on an output display (not shown). 
If the compartment 282 is not full, the lower one of the belts 252 is 
raised to engage the bottom surface of the slave cassette 28. When the 
lower one of the belts 252 (FIG. 23) has engaged the bottom surface of the 
slave cassette 28, the fingers 228 (FIG. 17A) are removed from engaging 
the rear periphery of the slave cassette 28. When the fingers 228 have 
cleared the slave cassette 28, the slave cassette 28 is rotated from the 
90.degree. position through a few degrees (e.g. 4.degree.) toward the 
0.degree. position. This allows the slave cassette 28 to become clear of 
the spring clips 132 (FIG. 3). The mechanism (FIGS. 15-17A) including the 
gears 180 and 182 is then retracted toward the 80.degree. position from 
the 86.degree. position and the belts 252 (FIG. 23) are operated to move 
the slave cassette 28 to the shelf 280 (FIG. 24). 
A determination is then made as to whether the image on the mirror-master 
tape 10 has been properly recorded on the slave tape 12. If the 
determination is in the negative, the subroutine is completed and the 
slave cassette 28 holding this slave tape is removed and therefore not 
advanced into the compartment 282. The lower one of the belts 252 is then 
lowered and the pins 312 and 314 are rotated as shown in FIGS. 25-27 to 
move the slave cassette 28 into the compartment 282. 
The apparatus and method described above have certain important advantages. 
They provide for a transfer of slave cassettes in sequence from the supply 
station 120 to the 15.degree. position or station where the threading arms 
138 and 140 and the dancer arm 78 are extended. The slave cassettes 28, 
the threading arms 138 and 140 and the dancer arm 78 are then moved to the 
0.degree. position or station and the slave tape is disposed on the guide 
68, the heater 70 and the capstan 72 by retracting the threading arms 130 
and 140 and the dancer arm 78 and by moving the articulator 64 to the 
operative position shown in FIG. 1. A similar procedure to that specified 
above is provided for the master cassette 21 when a different image than 
that previously provided is to be transferred to the slave tapes 12. 
The image on the mirror-master tape 10 is then transferred to the slave 
tape 12 in the slave cassette 28. The image transfer is provided so that 
the beginning of the image or movie is at the beginning of the slave tape 
12 when the slave tape is wound on the take-up reel 24 for the slave 
cassette 28. In this way, the slave tape 12 in the slave cassette 28 is in 
a position to be used by a viewer. The slave cassette 28 is then 
transferred to the output station 50 and is transferred into the station 
for disposition in a stacked relationship. 
FIG. 36 is a schematic block diagram of a system for regulating the heat 
produced by the heater 172 and for providing an almost instantaneous 
heating of the heater on a regulated basis when the apparatus shown in 
FIGS. 1-35 initially becomes operative. In FIG. 36, the heater 70 is shown 
as an equivalent electrical resistance. The system shown in FIG. 36 
includes a potentiometer 380 having an adjustable arm 382. The voltage on 
the adjustable arm 382 is introduced to a circuit 384 which multiplies the 
adjustable voltage by a transfer function such as a time constant to 
obtain a signal representing the desired amount of power to be introduced 
to the heater 70. 
The signal from the time constant circuit 384 is introduced to a 
differencing circuit 386 which also receives a signal input from a 
wattmeter 388. The output from the differencing circuit 386 is introduced 
to an integrator 390. The output from the integrator 390 in turn passes to 
a stage 392 for obtaining a square root of the output from the integrator. 
The output from the square root stage 392 then passes to a multiplier 394 
which also receives a signal on a line 396. The signal on the line 396 is 
an alternating signal having a particular waveform such as a sine wave or 
a square wave. A power amplifier 398 receives the output signal from the 
multiplier 394 and introduces an amplified signal to the heater 70. The 
input current and voltage to the heater are introduced to the wattmeter 
388. 
As will be seen, the system shown in FIG. 36 constitutes a closed loop 
servo for regulating the power introduced to the heater 70 in accordance 
with a desired amount of power represented by the voltage on the 
adjustable arm 382 of the potentiometer 380. This voltage is varied by the 
time constant provided by the stage 384. The resultant signal represents 
the desired power to be introduced to the heater 70. 
The resultant signal from the stage 384 is introduced to the comparator 386 
for comparison with the signal from the wattmeter 388. The signal from the 
wattmeter 288 represents at each instant the amount of power generated by 
the heater 70 at that instant. The output from the differencing circuit 
386 accordingly represents at each instant any difference between the 
desired power and the actual power introduced to the heater 70 at that 
instant. 
The difference signal from the differencing circuit 386 is introduced to 
the integrator 390 which integrates the difference signal at progressive 
instants of time. The output from the integrator 390 is introduced to the 
stage 392 which determines at each instant the square root of the output 
from the integrator 390. The output from the stage 392 accordingly 
represents the power introduced to the heater 70 at that instant. 
The square root output from the stage 392 is in the form of a variable 
direct voltage. This signal is introduced to the multiplier 394 for 
multiplication with an alternating signal, such as a sine wave signal or a 
square wave signal, on the line 396. The resultant alternating signal is 
amplified by the amplifier 398 and the amplified signal is introduced to 
the heater 70. 
In this way, the heat produced in the heater 70 at each instant is 
regulated in accordance with a desired amount of heat as represented by 
the voltage on the adjustable arm 382 of the potentiometer 380. The square 
root function 392 assures a relatively constant servo loop gain. Without 
the square root function 392, relatively small changes in the position of 
the potentiometer arm 382 at typical operating powers will cause large 
instantaneous changes in the heater power. It will be appreciated that the 
potentiometer 380 can be replaced by other command means such as a 
digital-to-analog converter connected to a microprocessor. The system 
shown in FIG. 36 and discussed above provides this regulation on an 
instantaneous basis. For example, this regulation is provided in less than 
a second after the slave tape 12 starts to move. 
The time constant stage 384 and the integrator 390 may be caged while the 
system shown in FIGS. 1-35 is not in use. When the time constant stage 384 
and the integrator 390 are caged, a low amount of power is introduced to 
these stages to prepare the system shown in FIG. 36 for instantaneous 
operation when the transfer of information from the master tape 10 to the 
slave tape 12 is initiated. When the transfer of information from the 
mirror-master tape 10 to the slave tape 12 is initiated, the time constant 
stage 384 and the integrator 390 are uncaged. 
When the slave tape 12 passes over the heater 70 and the capstan 72 with 
the capstan 72 disposed in abutting relationship to the pinch roller 50 
and with the capstan and the pinch roller at the 0.degree. positions, the 
heater 70 heats the thermomagnetic layer 14 on the slave tape above the 
Curie temperature. The thermomagnetic layer 14 in the slave tape 12 can 
have about five hundred milligrams (500 mg) of water for an eight hundred 
foot (800') tape. Some of this water is converted to steam by the heat 
from the heater 70. The steam causes the thermomagnetic layer 14 of the 
slave tape 12 to become separated from the surface of the heater. The 
steam also constitutes a variable barrier to the transfer of heat from the 
heater 70 to the thermomagnetic layer 14 on the slave tape 12. Similarly, 
other materials in the tape with volatile properties, as well as air, can 
cause a thermal barrier to the transfer of heat. 
The system constituting this invention regulates at a substantially 
constant value the amount of power transferred by the heater 70 to the 
thermomagnetic layer 14 on the slave tape 12. When the steam produced from 
the water in the thermomagnetic layer 14 causes the thermomagnetic layer 
14 to be separated from the external surface of the heater 70, the 
constant power from the heater causes the temperature of the heater to 
rise to such a temperature that the constant power is conducted through 
the steam barrier to the thermomagnetic layer. This localized increase in 
the temperature of the heater 70 sometimes causes the heater to crack 
after a relatively limited period of time. 
To increase the life of the heater 70, the system of this invention removes 
some of the water from the thermomagnetic layer 14 on the slave tape 12 
before the image on the mirror-master tape 10 is transferred to the 
thermomagnetic layer. For example, the system of this invention may remove 
about two hundred milligrams (200 mg) of water from the thermomagnetic 
layer 14 on the slave tape 12. By removing this water from the 
thermomagnetic layer 14 on the slave tape 12, the system of this invention 
inhibits the thermomagnetic layer 14 from becoming separated from the 
heater 70 during the transfer of the image on the mirror-master tape 10 to 
the thermomagnetic layer 14 on the slave tape 12. 
Two alternative arrangements may be provided for removing water from the 
thermomagnetic layer 14 of the slave tape 12 before the image on the 
mirror-master tape 10 is transferred to the thermomagnetic layer 14 on the 
slave tape 12. In one arrangement, the heater 70 is heated with the 
capstan 72 and the heater at the 0.degree. position. The pinch roller 50 
can be displaced from the capstan 72 or preferably can be disposed in an 
abutting relationship with the capstan. In this arrangement, the tape is 
moved in a direction opposite to that in which the image on the 
mirror-master tape 10 is transferred to the thermomagnetic layer 14 on the 
slave tape 12. The operation of the heater 70 may be under the control of 
the controller 84 in FIG. 1. 
In the other arrangement, the capstan 72 and the heater 70 may be at the 
15.degree. position. In this arrangement, the slave tape 12 may be passed 
through a microwave oven 400 (FIG. 40) whose operation is regulated to 
remove water from the thermomagnetic layer of the slave tape. At the 
15.degree. position, the pinch roller 50 does not abut the capstan 72. As 
will be appreciated, this occurs before the slave tape 12 is moved to the 
0.degree. position. Alternatively, the microwave oven 400 may be disposed 
at the 0.degree. position and the water may be removed by the microwave 
oven from the thermomagnetic layer 14 of the slave tape 12 in either the 
rewind or the transfer directions of the slave tape or in both directions. 
It will be appreciated that the water can be removed from the tape 12 
without converting the water to vapor. This is considered to be within the 
scope of applicants' invention. The water can also be removed from the 
tape 12 at a temperature below the Curie temperature if the Curie 
temperature is relatively high. It is also within the scope of the 
invention to remove the water from the tape 10 during the step of 
transferring the information on the mirror-master tape 10. For example, 
the speed of the mirror-master tape 10 and the slave tape 10 can be 
reduced during the transfer of the information on the master tape to the 
slave tape to remove the water from the slave tape during the transfer 
process. 
As previously described, the slave tape 12 is heated above the Curie 
temperature when it reaches the capstan 72 during the operation of 
transferring the image on the mirror-master tape 10 to the thermomagnetic 
layer 14 on the slave tape. The thermomagnetic layer 14 on the slave tape 
12 then becomes cooled by the mirror-master tape 10 below the Curie 
temperature when it contacts the mirror-master tape 10 at the abutting 
positions of the capstan 72 and the pinch roller 50. In this way, the 
image on the mirror-master tape 10 becomes transferred to the 
thermomagnetic layer 14 on the slave tape 12 at the abutting positions of 
the capstan 72 and the pinch roller 50. 
Although the temperature of the thermomagnetic layer 14 on the slave tape 
12 is below the Curie temperature at the abutting position with the 
mirror-master tape 10, this temperature is significantly above ambient. 
This causes the slave tape 12 to be stretched significantly in length 
relative to its length at ambient temperatures. When the length of the 
thermomagnetic layer 14 on the tape 12 has contracted from its length at 
the elevated temperatures to its length at ambient temperatures, errors 
are produced in the image on the slave tape 12 if a compensation has not 
been provided for the contraction in the length of the slave tape. These 
errors result from the contraction in the lengths of the lines in the 
raster scans defining the image on the thermomagnetic layer 14 of the 
slave tape 12 when the thermomagnetic layer contracts from its length at 
the elevated temperatures to its length at ambient temperatures. 
To overcome the disadvantage discussed in the previous paragraph, 
compensation should be provided for the contraction in the length of the 
lines in the raster scan on the thermomagnetic layer 14 of the slave tape 
12 as the length of the slave tape contracts from its length at the 
elevated temperatures to its length at ambient temperatures. This 
compensation may be provided by increasing the length of the lines in the 
raster scan on the mirror-master tape 10 relative to the length of the 
lines in the raster scan on a master tape 410. 
In one embodiment shown in FIG. 37, the mirror-master tape 10 may be 
disposed on a rotary member such as a cylinder 414 and the master tape 410 
may be disposed on a rotary member such as a cylinder 416. The cylinder 
414 may be provided with a greater diameter than the cylinder 416. The 
relative diameters of the cylinders 414 and 416 may correspond to the 
relative lengths of the slave tape 12 at the elevated temperatures when it 
contacts the mirror-master tape 10 and at the ambient temperature of the 
slave tape after it has cooled. 
In the relationship discussed in the previous paragraph, the cylinders 414 
and 416 may be rotated at the same angular speeds. During such rotations, 
the information on the master tape 410 may be read by a magnetic head 418 
disposed in contiguous relationship to the master tape and may be 
transferred to the mirror-master tape 10 by a magnetic head 420 disposed 
in contiguous relationship to the mirror-master tape. The resultant lines 
in the raster scan on the mirror-master tape 10 have the same stretched 
relationship as the lines on the slave tape 12 when the slave tape is at 
the elevated temperature. When the slave tape 12 cools to an ambient 
temperature, the lines in the raster scan on the thermomagnetic layer 14 
of the slave tape 12 have the same relationship as the lines in the raster 
scan on the master tape 410. Furthermore, the width of the slave tape 12 
at ambient temperatures corresponds to the width of the master tape 410. 
In this way, the image on the slave tape 12 at ambient temperatures is a 
duplicate of the image on the master tape 410. 
As previously described, it is desirable to wind the slave tape 12 on the 
supply reel 22 in the slave cassette 28 through a distance corresponding 
to the length of the image on the mirror-master tape 10. During this time, 
the image on the mirror-master tape 10 is transferred to the 
thermomagnetic layer 14 on the slave tape 12. In this way, the slave tape 
cassette 28 is ready for the image on the thermomagnetic layer 14 of the 
slave tape 12 to be displayed to a viewer. 
In order to transfer the image on the mirror-master tape 10 to the 
thermomagnetic layer 14 on the slave tape 12 so that the full image is 
provided on the thermomagnetic layer and the slave tape is in position to 
display the image without any lost time in the playback operation, the 
length of the image on the mirror-master tape 10 has to be known. This can 
be determined by techniques well known in the art. It is also desirable to 
know the length of the slave tape. This can be determined by arrangements 
individual to this invention. From the length of the image on the master 
tape and the length of the slave tape, a determination can be made of the 
angle through which the slave tape has to be wound on the supply reel 22 
or unwound from the take-up reel 24 in the cassette 28 in order for the 
image on the mirror-master tape 10 to be transferred to the slave tape 12 
without any excess length of the slave tape on the supply reel. 
One arrangement for determining the length of the slave tape 12 includes 
the use of a reference tape 430 (FIG. 38) of a known length such as eight 
hundred feet (800'). This tape is wound on one of the supply reel 16 or 
the take-up reel 18 in the mirror-master tape cassette 21 and the slave 
tape 12 is disposed on the supply reel 22 or the pinch roller 24. In FIG. 
38, only the take-up reel 18 is shown. The capstan 72 and the pinch roller 
50 are disposed in contiguous relationship in the 0.degree. position. 
The capstan 72 and the pinch roller 50 are then rotated so that the 
reference tape 430 becomes transferred between the supply reel 16 and the 
take-up reel 18 in FIG. 1. The angular revolution of the capstan 72 is 
then measured. The length of the reference tape can be divided by the 
angular revolution in moving the reference tape from the tape beginning to 
the tape end to give the distance per revolution of the capstan, which is 
the circumference of the capstan. Thereafter, as a tape of unknown length 
is moved in a non-slipping contact with the capstan, the length of the 
tape is defined by the previously determined circumference of the capstan 
times the number of revolutions of the capstan. 
In another arrangement shown in FIG. 39, a mirror-master tape is run from 
leader to leader, that is, from end to end, and the revolution angle of 
the capstan 72 is measured during this tape movement. The revolution angle 
is a measure of the length of the tape. The length of the tape is stated 
as the number of revolutions of the capstan. The actual length in a 
defined unit such as meters is not known. If the slave tape 12 is moved on 
the same capstan, its length can also be stated in terms of the number of 
the number of revolutions of the capstan. 
The image on the mirror-master tape is begun not at the beginning of the 
mirror-master-tape but rather the image is begun at some relatively small, 
but defined, distance from the beginning of the mirror-master tape 10. For 
example, the image can begin one meter (1 m.) from the beginning of the 
mirror-master tape 10. Likewise, the image stops a known distance from the 
end of the mirror-master-tape 10 e.g., a distance of 2 two meters (2 m.). 
The image on the slave tape 72 can start at the beginning of the slave 
tape, not after some distance as is the case for mirror-master tapes. For 
image transfer, the slave tape beginning is placed at the beginning of the 
image on the mirror-master tape, not at the mirror-master tape beginning. 
The positioning of the master tape relative to the beginning of the slave 
tape is located with little error because the diameter of the capstan can 
be illustratively known to two tenths of one percent (0.2%) accuracy. If 
the capstan diameter is known to such accuracy, the error is small in 
computing the one meter (1 m.) distance in terms of the circumference and 
the number of revolutions of the capstan. The beginning of the slave tape 
12 is located one meter (1 m.) from the beginning of the mirror-master 
tape 12, and therefore the image transfer starts at the beginning of the 
slave tape. The measurement of the distance of the two tapes in contact is 
made by using revolutions of the capstan, rather than computed distances, 
since the known master tape was measured in terms of revolutions of the 
capstan. This insures high length accuracy for images that can be hundreds 
of meters long. 
Another arrangement shown in FIG. 39 for determining the length of the 
slave tape 12 can also be used. In this arrangement, the slave tape 12 is 
transferred between the supply reel 22 and the take-up reel 24. As this 
transfer occurs, the angular revolutions of the supply reel 22 and the 
take-up reel 24 are respectively measured by detectors 440 and 442 at 
three (3) successive instants of time. Subscripted symbols are used to 
represent the rotation angles of the reels 22 and 24. The first number in 
the subscript is 1 for the reel 22 and 2 for the reel 24. The second 
number in the subscript indicates the measurement instant of time. For 
example, 1 indicates the first measurement instant of time and 3 indicates 
the third measurement instant of time. For example, a representation 
.theta..sub.11 indicates the first measurement instant of time of rotation 
angle in the reel 22. Similarly, a representation .theta..sub.23 indicates 
the third measurement instant of time of the rotation angle in the reel 
24. 
From the above, an equation can be written as follows: 
##EQU1## 
In the above equation, .theta..sub.f indicates the angular rotation of a 
particular one of the capstan 72, the supply reel 22 or the take-up reel 
24 to transfer the slave tape 12 between the supply and take-up reels. 
A measurement is then made of the radius of the particular one of the 
supply reel 22 or the take-up reel 24 without any tape on such reel. As an 
alternative, the radius may be assumed to be known from the specifications 
for that type of cassette. For an empty reel of a radius R, the thickness 
d of the slave tape 12, may be determined from the following equation: E1 
? ? 
##STR1## 
The length S.sub.f of the slave tape 12 may then be determined from the 
following equation: 
##EQU2## 
The angular revolution B of the particular one of the supply reel 22 and 
the take-up reel 24 for transferring an image of length L to the slave 
tape 12 may then be determined from the following equation: 
##EQU3## 
In the above equation, L indicates a desired length of tape, e.g. the 
length of the image on the slave tape 12. 
Another arrangement shown in FIG. 39 for determining the length of the 
slave tape 12 can also be used. In this arrangement, the slave tape 12 is 
transferred between the supply reel 22 and the take-up reel 24. The 
relationship between the length of the slave tape 12, the radius of the 
spool, the thickness of the tape, and the number of turns of the tape on 
the spool is: 
EQU S=N.pi.(2R+Nd) (5) 
where 
N=the number of turns of the tape; 
R=the radius of the spool; 
d=the thickness of the tape; 
S=the length of the tape. 
This equation can be solved for any one (1) of the four variables in terms 
of the other three. 
Initially the cassette has an empty spool and a more full spool. The length 
of tape run at any instant is known through the measurement of the 
revolutions of the capstan. The number of revolutions of the empty 
cassette is measured for a small number of revolutions, e.g. eight (8) 
revolutions. Assume a tape thickness such as nineteen microinches 
(19.mu."). Using the formula (5) above, the radius of the hub can be 
computed. The error in the hub radius is small, since the error caused by 
the tape thickness being off by, e.g. ten microns (10 .mu.), is small for 
the eight (8) turns. 
For this same instant, consider the more full spool. Using the same tape 
thickness assumed earlier, the number of revolutions of the more full 
spool is measured. A measurement is also made of the length of tape 
removed from the spool which equals the length of the tape measured by the 
revolutions of the capstan. Using the formula (5) above, the radius of a 
fictitious large hub on the more full spool is computed. 
Assume that the hub radius on the more full spool is in fact not the radius 
of the fictitious hub, but rather it is the radius of the empty hub 
already computed. Then the number of layers of tape between the fictitious 
radius and the empty hub radius is the difference between them divided by 
the assumed tape thickness. Add to this number of layers the number of 
turns measured for the more full spool. Now solve the formula for the 
length of the tape on the full reel using the number of turns on the more 
full spool, using the computed empty hub radius, and using the assumed 
thickness of the tape. This is the first (not so accurate) estimate of the 
total length of the tape on the cassette. 
When the spools have run to about one third of the tape length computed 
above, compute the tape thickness using the number of revolutions of the 
empty spool, the radius of the hub, and the length of the tape as metered 
by the revolutions of the capstan. This is an accurate measure of the tape 
thickness, and the total length of tape can be computed using the method 
of the previous paragraph. Thus the tape length, the tape width, the 
number of turns, and the hub radius can be computed. 
Although this invention has been disclosed and illustrated with reference 
to particular embodiments, the principles involved are susceptible for use 
in numerous other embodiments which will be apparent to persons skilled in 
the art. The invention is, therefore, to be limited only as indicated by 
the scope of the appended claims.