Cassette system having quick connect feature

Film (13) in a film cassette (15) is connected to a take-up reel (19) in a film transport mechanism (11) by means of mating connectors (20,30) attached to leaders (27,29) on the cassette film (13) and on the take-up reel (19). The connectors (20,30) are retained in contoured slots (41,51) on the cassette (15) and on the film transport mechanism (19) so that when the cassette (15) is loaded onto the transport mechanism (19), the connectors (20,30) will be in alignment. By arranging the connectors (20,30) for connection and disconnection in a direction perpendicular to the direction of travel of the film (13), an efficient connection can be effected and the connection remains stable during the operation of the film transport mechanism (11). In order to avoid the connectors (20,30) causing a distortion in the contour in the film (13) after winding onto the take-up reel (19), the leader (29) attached to the take-up reel (19) is provided with apertures (57) which, when the film (13) is wound around the take-up reel (19), are in alignment with the mated connectors (20,30). The use of the mating connectors (20,30) establishes a fixed relationship in the spacing between the film leader (29) on the take-up reel and an "initial" position on the film (13). If the film (13) is controlled in its position by a sprocketed capstan (35), the use of the mating connectors (20,30) reduces the possibility of positional error occurring as a result of an inaccuracy in the positioning of the film (13) when loading.

BACKGROUND OF THE INVENTION 
This invention relates to end feeding of webs from cassette packages, and 
more particularly to a system for accurate and automatic connection of a 
web from a cassette reel to a take-up mechanism in a transport assembly 
which is external to the cassette. The inventive system is particularly 
advantageous when used with non-continuous lengths of sprocketed film 
mounted about a single reel in a cassette. 
Cassette loading systems for feeding continuous webs must include a 
provision for some means to drive a web feeding mechanism. In some cases, 
it is not necessary to accurately position the web. In cases where it is 
necessary to accurately position the web, some means of providing 
information relating to initial position must be included either as 
information on the web or from a drive mechanism. 
In mechanisms using a web feed, it is desireable that most of the web feed 
mechanism be located outside of the cassette, in order that a single web 
feed mechanism may be used for a plurality of cassettes. 
Film in a continuous web, when unreeled from a cassette, must be wound onto 
the take-up reel in order to economize on space. If a specialized 
connector is used at the beginning of the film, this connector can cause 
the film to bulge at the place on the take-up reel where the connector 
rests. For this reason, film systems using connectors have not been 
popular. On the other hand, a connector establishes a positive positioning 
device. On systems in which it is established that a connector attachment 
must first be effected in order to effect transport of the film, it is 
very difficult to inadvertently position the film at an incorrect initial 
position. The only remaining sources for positional error would then be 
programming errors and errors derived from misinformation. 
In vehicle mounted moving map displays, it is desired that the vehicle's 
position and orientation correspond to a set of coordinates shown on the 
displayed map. When map information is provided in the form of a 
photographic film strip, the information contained in the film strip does 
not readily convey positional information. Directional orientation and a 
"y" position are determined by an orientation of a flying spot scanner's 
raster with respect to the direction and width, respectively, of the film 
strip, or in a similar manner by mechanical movements. The "x" position, 
on the other hand, is determined by the distance to which the film is 
transported out of the cassette feed reel to the mechanism's take-up reel. 
Film cassettes containing this type of map information are typically 
indexed by sprockets along the edges of film strip. For example, in one 
application, 35 mm film which meets the specifications of American 
National Standard Motion Picture Film is used. Positioning information is 
provided by a sprocketed capstan. The capstan's total rotational travel is 
indicated by an encoder assembly driven by the capstan. It is important 
that the initial position of the film be accurately established in order 
that a substantial initial positioning error not be transferred to 
subsequent film indicia. 
While it is important that the map be accurately positioned with respect to 
the vehicle for the purposes of the external visual reference of the pilot 
or vehicle operator, overlay information is typically provided on a moving 
map display in conjunction with the map material. For example, a 
down-looking radar assembly may provide such overlay information, in which 
the overlay information is expected to more-or-less coincide with the map 
information. It is important that other information, such as target 
designations, also coincide with information provided on the map. 
In order to accurately establish the initial "x" position of the film 
strip, it is necessary to carefully feed film leader from the cassette to 
film leader attached to the take-up mechanism. If this feeding is 
accomplished to the accuracy of the nearest sprocket, it is possible to 
identify the initial position of the film strip. Such a procedure has 
entailed cumbersome manipulation of film leader and was prone to cause 
positional inaccuracy as a result of the film being inaccurately 
positioned with respect to its initial sprocket position. Furthermore, 
prior art manual attachment of film leader from the cassette to film 
leader in the take-up assembly requires a great deal of manual 
manipulation of the film in order to achieve the desired result. In cases 
where the film is inaccessible or where time between different sorties is 
critical, such as requirement for manual manipulation of film leaders in a 
map reading system is not acceptable. 
It is desired to provide an arrangement for efficiently and accurately 
connecting film leaders in a cassette to a film leader attached to a 
cassette drive mechanism. It is therefore an object to provide a quick 
connect feature for rapidly loading film cassettes. It is a further object 
to provide a system in which loaded film cassettes are accurately 
positioned with respect to their initial film position. It is a further 
object to provide a system for loading film cassettes in which the film or 
film leader need not be manipulated in order to load the cassette. It is 
also an object to provide a film cassette loading system in which a film 
cassette can be loaded into a receiving drive mechanism in a place in 
which manuevering or visual inspection of the film would be difficult. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a film cassette loading system is 
provided in which film leader attached to a take-up spool in a film 
transport assembly is mated with film leader on a cassette. The mating is 
accomplished by a mechanical pin-and-socket connector pair, in which the 
pin and the socket have axes parallel to a transverse line on the film. 
Mating is accomplished when the film cassette is loaded into the film 
transport assembly. The connectors are retained in a position for 
engagement and disengagement by retainer arrangements on the cassette and 
on the transport assembly. The retainer arrangement on the cassette 
provides retention force for the cassette's connector when the connector 
is in the engagement/disengagement position, while allowing the film to 
move freely past the retainer arrangement after the film web has begun to 
be played into the transport assembly. 
In order to prevent the connectors from creating a distorting lump when the 
film is wound around the transport assembly's take-up spool, a recess is 
provided on the take-up spool and corresponding apertures are provided on 
the transport assembly's film leader. The apertures and recess correspond 
to the wound position of the connectors against the take-up spool. The 
film leader from the cassette then acts to press the connector pair 
through the apertures in the film leader and toward the recess in the 
take-up spool. As a result, film which is wound around the take-up spool 
retains a relatively circular profile, while allowing the mating pair of 
connectors to be wound about the inside of the film roll. 
In one embodiment, the invention contemplates a single film cassette design 
for an optical or electronic map reader device in which the cassette 
contains a single spool which contains the map information on film. The 
cassette housing completely encloses the film to protect the film from 
damage due to handling and to provide a means for film storage. The 
invention provides for automatic engagement of the film to a film leader 
installed in the map reader and eliminates the need for a delicate 
threading and calibration operation. Indexing of the film is accomplished 
through a film sprocket which is geared to a plurality of position 
transmitters which determine the film positioning for any area of the map. 
One section of film leader remains in the map reader attached to a take-up 
spool and initially engages the film sprocket. A first mechanical 
connector attached to the film leader is captured in a contoured slot in a 
film gate and is held in position. When the cassette is installed, a 
mating connector which is attached to the film in the cassette engages the 
first coupler. Upon a command to advance the film, the film gate is 
opened, thus permitting a drive motor on the film take-up spool to advance 
the film out of the cassette. To remove the film cassette, the film must 
be rewound into the cassette. When the film is rewound into the cassette, 
the film gate closes and captures the coupler, thus permitting the 
cassette to be removed. 
By providing such an arrangement, the film is automatically positioned to 
an accuracy such that the initial sprocket location can be determined. 
Furthermore, quick changes of film cassettes can be effected and visual 
inspection of the connection is unnecessary.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
This invention relates to feeding of webs, such as continuous film strips 
for a moving map display. Typically, information from such film strips is 
optically read at a film transport mechanism 11, shown in FIGS. 1 and 2. 
The film transport mechanism 11 withdraws film 13 from a film cassette 15, 
shown in FIG. 3. While two-reel film cassettes are known, the present 
invention uses film cassettes, such as film cassette 15, which have a 
single reel known as a supply reel 17. The film transport mechanism 11 
houses a second reel known as a take-up reel 19. The take-up reel 19 is 
located in the film transport mechanism 11 partly because the film 
transport mechanism 11 must be fairly complex in order to accurately 
determine the distance that the film 13 has been taken up by the film 
transport mechanism 11. 
As will be seen later, the film 13 in the cassette includes a mechanical 
connector 20 which is retained in an initial position (shown in FIG. 3) by 
a catch 22. Typically, the film 13 begins with a leader portion 27 which 
is identical to the remaining portion of the film 13, except that normal 
film information is not carried on the leader 27 and the leader 27 often 
has more strength than the remaining portion of the film 13. Referring to 
FIGS. 1 and 2, the film transport mechanism 11 has associated with it, 
film take up leader 29, which is attached to the take-up reel 19. The 
take-up leader 29 has, associated with it, a mechanical connector 30, 
which can mate with the connector 20 associated with the film 13 on the 
cassette 15. 
The film transport mechanism 11 includes an optical assembly such as a 
flying spot scanner (FSS) 33 (partially shown) and a film position 
transducer. The film position transducer includes a sprocketed capstan 35 
which is geared to a series of servo transducers 36 which are capable of 
providing an indication of the number of turns that the sprocketed capstan 
35 has rotated. In the preferred embodiment, three servo transducers are 
adequate to provide an indication of film positioning for any area of the 
map. The film 13, and film leaders 27, 29 include a series of evenly 
spaced sprocket holes 37 in accordance with standard film practice. In the 
preferred embodiment, 35 mm film is used and the sprocket holes are 
provided with dimensions per American National Standard Motion Picture 
Film standards. It is also possible to use film having different 
dimensions and different sprocket standards. The film 13 has an "initial" 
position in which map information to be displayed begins. Since the map 
information does not readily electronically identify itself with 
navigational data, the "initial" position must be established by further 
inputs to the transport mechanism's control system (not shown). By 
measuring this distance of the cassette's film leader 27 to the "initial" 
position, and by measuring the distance that the cassette film leader must 
travel in order to engage the sprocketed capstan 35, the distance that the 
film must travel to reach the "initial" position is established. The film 
position transducer is then able to determine the distance of film travel 
essentially by counting the number of sprocket holes 37 which the 
sprocketed capstan 35 engages. An idler capstan 39 is used to retain the 
film 13 in engagement with the sprocketed capstan 35. 
In the preferred embodiment, the position of the transport assembly's film 
leader 29 at the start of engagement is determined by the physical 
constraints of the transport assembly 11. The sprocketed capstan 35 
therefore merely follows the position of the film 13 or film leader 27, 
29. It is important that the distance between the capstan 35 and the film 
transport mechanism's optical system 33 by fixed within a desired accuracy 
of calibration. However, when the film transport's take-up leader 29 is 
connected to the cassette's leader 27, the respective connectors 30, 20 
are mated as will be described and maintain the fixed relationship of the 
film 13 with respect to the sprocketed capstan 35. It is important only 
that this accuracy be maintained to an extent necessary for allowing the 
sprocketed capstan 35 to engage sprocket holes 37 on the cassette's leader 
27 successively after engaging sprocket holes on the transport assembly's 
take-up leader 29. After the connectors 20, 30 have passed the sprocketed 
capstan 35, the position of the film 13 depends upon the capstan 35 
engaging successive sprocket holes 37 on the film strip 13, rather than on 
the possible movement of the connectors 20, 30. This is also important 
because the film 13 may slightly change its physical dimensions with age 
and changes of temperature, but distances from specific map features to 
nearby sprocket holes 37 is not subject to cumulative error and will not 
be significantly changed despite changes in the total length of the film 
strip 13. 
It should be noted that, while the use of the mating connectors 20, 30 
allows the "initial" position of the film strip with respect to leader 29 
to be pre-determined, the invention would work equally well with a system 
in which the "initial" position is given by electronically readable data 
on the film strip 13 itself. Thus, the present invention can be used with 
a system in which electronic data may or may not be encoded on the film. 
Conversely, the present system can ignore such film-encoded data, provided 
that the position of the cassette's connector 20 is known. 
Referring to FIGS. 3-5, the film 13 from the cassette 15 is fed from the 
cassette 15 through a slot 41. Referring to FIG. 5, slot 41 is contoured 
so that the cassette's connector 20 can be drawn only partially into the 
slot 41. The cassette's connector 20 has a cylindrical outer contour and 
includes a flange 43, which attaches to the film leader 27. The 
cylindrical shape of the connector 20 has an axis which extends parallel 
to the transverse direction of travel of the film 13. Referring to FIG. 1, 
connector 30 on the transport mechanism's film leader 29 has a similar 
profile. Referring also to FIGS. 2 and 5, one of the connectors 30 has a 
bore 45 along its center axis which is designed to engage a corresponding 
pin 46 on the other connector 30. The pin and bore are aligned 
perpendicularly to the direction of travel of the film 13 and therefore 
engage the connectors 20, 30 without urging the connectors 20, 30 to 
separate during travel of the film 13. On the other hand, if the cassette 
15 is placed into position on the film transporter mechanism 11 by a 
movement perpendicular to the direction of travel of the film 13, 
alignment of the pin 46 with the bore 45 causes the connectors 20, 30 to 
automatically become engaged upon insertion of the film cassette 15. It 
turns out that insertion of the film cassette 15 perpendicularly to the 
direction of travel of the film 13 is convenient because the perpendicular 
movement avoids any displacement of the film 13 in the direction of travel 
during the insertion process. 
In order to retain the cassette's film connector 20 in an appropriate 
position for engagement, the cassette's slot 41 has a contour which 
determines the position of the cassette's connector 20. In order to 
maintain that position, the catch 22 engages the cassette's connector 20 
so as to create a force to bias that connector 20 to remain in its start 
position. This biasing force is supplied by a cantilever rod spring 49, 
which presses against the catch 22 so as to create the biasing force. The 
amount of travel of the catch 22 is such that, when the narrower film 13 
passes through the slot 41, the catch 22 does not engage the film 13. 
Referring to FIG. 1, a film gate assembly 50 supports the take-up film 
leader 29 or the film 13 at the flying spot scanner 33. The film gate 
assembly 50 terminates with a contoured slot 51, although a catch 
corresponding to catch 22 is not used on the transport mechanism 11. 
Instead, the transport mechanism 11 unwinds the transport mechanism's film 
leader 29 until its connector 30 engages against its slot 51. The film 
gate assembly 50 includes a film gate 52 which is caused to pivot open by 
a solenoid 55. This pivoting open enables the film, which typically is 
transported at speeds up to about 20 meters/minute, to clear the film gate 
assembly during such high speed transport. 
The film gate 52 extends to contoured slot 51 and includes an articulated 
half 54 of slot 51. The movement of the film gate 52 including the 
articulated half 54 of slot 51 allows connector 30 to be released from the 
transport mechanism's contoured slot 51 whenever the film gate 52 is 
opened. 
It is also possible to avoid the use of an articulated part 54 of slot 51. 
Since the wide part of slot 51 faces the direction of the take-up reel 19, 
excess movement of the transport mechanism's film leader 29 to an unwound 
position would cause the transport mechanism's connector 30 to press 
against its slot 51 and consequently cause the leader 29 to buckle, 
presumably in a non-destructive fashion. 
Referring to FIG. 1, a tab 59 is pivotably mounted at the transport 
mechanism's contoured slot 51. The tab 59 is positioned so that the 
transport mechanism's connector 30 displaces the tab 59 to a "release" 
position (shown) when connector 30 is present in the slot 51. The tab 59 
is biased against such displacement so that when connector 30 is not in 
the slot 51, the tab 59 moves to a "lock" position. The function of the 
tab 59 is to prevent the cassette 16 from being removed or fully inserted 
when connector 30 is not in position. Therefore the cassette cannot be 
removed with the film 13 from the cassette 15 partially withdrawn. 
Secondarily, the tab 59 mandates that connector 30 be in approximate 
alignment at the slot 51 prior to inserting the cassette 15. 
After engagement, the connectors 20, 30 are aligned, as established by the 
bore 45 and the pin 46. This establishes the distance between the 
sprockets on the cassette's film 13 and leader 27, and the position of the 
transport mechanism's take-up leader 29. 
As the take-up reel 19 takes in the film 13, the connectors 20, 30 are 
necessarily wound around the take-up reel 19. As can be seen, the 
connectors 20, 30 are considerably thicker than the film 13. This would 
necessarily create a bulge in the film 13 as the film is wound around the 
take-up reel 19. In order to avoid this, the take-up reel 19 has a recess 
60 at its hub. A series of apertures 57 are provided in the take-up leader 
29 in order to allow the connectors 20, 30 to move inwardly against the 
hub recess 60 as the film 13 is wound around the take-up reel 19. The 
position of the apertures 57 is, therefore, determined by the anticipated 
alignment of apertures 57 with the connectors 20, 30 when the connectors 
are wound against the take-up reel 19. While it is possible to provide 
additional apertures on the cassette's film leader 27, in the preferred 
embodiment, no such additional apertures are provided. The cassette's film 
leader 27 then acts to press the connectors 20, 30 inwardly through the 
apertures 57 toward the hub recess 60. Unless the film 13 and film leader 
27 are fairly thick, some bulge will remain in the film 13 on the take-up 
reel 19. This bulge will be insignificant as long as it does not hinder 
the operation of the transport mechanism 11. 
The displacement of the mated connectors 20, 30 toward the recess 60 may 
change the distance between the film leaders 27, 29. As previously 
mentioned, the position of the film 13 is controlled by the movement of a 
film 13 against the sprocket capstan 35. Therefore, any shifting in the 
distance between the film leaders 27, 29 after the film leaders 27, 29 are 
on the take-up reel 19 is irrelevant with respect to the accuracy of the 
positioning of the film information. 
In the present embodiment, the supply reel 17 is driven by a drive 
connection 61 on the film transport mechanism 11 after the cassette 15 has 
been placed into a position on the film transport mechanism 11. It is also 
possible to provide other methods of driving the supply reel 17, such as 
the use of a separate motor in the cassette 15 or by the use of biasing 
means. 
It should be noted that, while a single embodiment has been described, the 
present invention is useful with a plurality of systems in which a 
cassette is used to provide a web of material and the web of material is 
received on a take-up reel external to the cassette. It is particularly 
adapted to systems in which a mechanical connector pair is engaged by 
movement transverse to the movement of the web, so that all that is needed 
for engagement is an alignment of the connectors prior to engagement. It 
is possible to use the present invention with data means other than film 
strips, such as magnetic tape. These and other variations in the preferred 
embodiment being possible, it is desired that the present invention be 
limited only by the claims.