Note: Descriptions are shown in the official language in which they were submitted.
809P0~8A
11-29-84 - tPTO Copy ~
CA~R~ ~3ITEI I~PR~9:D FII~I Ll~DE:R
CAPll~RING ~IS
DESCRIPTION
1 - .
, Technical Field
¦ The present invention relates
I ~ generally to a still camera of the 35mm type
l . having a swing-open back door which when open
¦ exposes the interior of the camera housing for
film loading, and, more particularly, to a
unique take-up spool design and posltioning
control therefor which ensures receipt and
reliable capture of a film leader in a slot
therein when the take-up spool is su~sequently
rotated.
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The invention relates to a camera, and more
particularly to an improved film leader recapturing mechanism.
In the field of electrically operated 35 mm
cameras there exists a variety of means whereby -the camera
may be loaded rapidly and easily. A variety of approaches
have been used to accomplish this. One is disclosed in
U.S. Patent No. 4,416,525. An unslotted take-up spool with
one or more slightly radially projecting film-engaging
capture hooks disposed to engagingly capture a film leader
driven over and around the take-up spool by a sprocket,
motor-driven through a slip-clutch when the shutter release
button is depressed. Here the user need not bother about
threading the film leader through a slot in the take-up
spool, as was required by conventional cameras where occasionally
a hook on the spool projecting into the slot failed to capture
a film apexture, thereby making it impossible to advance
the film. Such film capture failure is believed due to
the fact that the slot and capture hook are not ideally
positioned or formed to ensure captuxe of the film leader~
In the patent described above, to insure that the capture
hooks disenga~e without tearing the film on rewind, the
take-up spool is driven overspeed with respect to the cassette
take-up
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rate during rewind, so as to shuffle the film
off automatically~ Where cost reduction is the
principal objective, as in the case of the
present invention, the prior requirement that
the user place the film leader in a take-up
spool slot is retained, but the leader capture
reliability is enhanced by the features of the
invention to be described, which involve less
expensive mechanism that that disclosed in said
patent. Other less desirable prior approaches
~o take-up spool film capture use a friction
coating such as a synthetic rubber-like coating
around the take-up spool, and loading gates and
feeding shoes to insure that the film is fed
around the spool during initial leader advance
to secure at least one tight turn thereabout.
80th of the àforementioned systems tend to be
inherently complex, and therefore expensive as
opposed to the long-standing method of
inserting the film into or through a suitably
disposed capturing slot in the take-up spool.
While not a requirement of the broad
aspects of the present invention, in a motor
driven embodiment thereof, as in said patented
camera, it is desirable that some form of
tension-sensing film feed control be
incorporated into the camera, wherein the
sudden build-up of film tension at and end-of-
film condition in the take-up spool is sensed
by one means or another to disable further film
advance, or to automatically switch the camera
into a rewind drive configuration, where the
ilm is automatically rewound into the
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cassette. Such tension-responsive system~
place a rather substantial load upon the take-
up spool drive, and hence on the take-up spool
itself, which must be sufficiently rugged to
withstand the tension surges involved. A
simple, rugged, small one-piece take-up spool,
preferably made as a single molded plastic
part, and capable of absorbing these tension
surges without fracture would be a desirabl~
feature of the most preferred form of the
invention
Prior to the present invention, to
the applicant's knowledge, there has no~ been
provided an inexpensive film-capture system for
a back-loading 35mm camera which is easi}y
threaâed in under adverse lighting conditions
without the use of special guide shoes or
related paraphenalia, which preserves the
requisite structural integrity of a small
diameter take-up spool under high stress
conditions, and which is of simple one-piece
inexpensive construction.
Summary of the Invention
According to a feature of the
invention the camera features a motor driven
take-up spool having a wide-aperture film-
capturing slot having a film-engaging hook
therein, the camera featurinq a means
preferably motor driven which enables the
positioning of the take~up spool in a precise
position so as to present the take-up spool
s
slot in an optimum position for placement and
capture of the film leader. In the preferred
form of the invention, where the camera uses an
electric motor for film wind and rewind, the
take-up spool is automatically moved into this
optimum position by this same motor responsive
to opening of the camera loading door attendant
to a film loading operation. To that end,
position sensing switching means are provided
associated with the take-up spool which, in
conjunction with a door-actuated switch,
energizes the motor to cause a partial rotation
of the spool to the ideal loading position.
In accordance with a specific aspect
of the invention, the take-up spool slot has a
unique size and shape. Thus, instead of being
a narrow slot formed in the periphery of a
cylindrical, thin, hollow shell forming the
take-up spool, with a hook projecting
substantially into the slot! as in the case of
the take-up spool disclosed in copending Canadian
Patent Appln. 450,121, filed March 21, 1984, the slot
has a much greater width and the capture hook
projects only slightly into the slot. ~lso the
slot is preferably formed in a take-up spool
which is a thick-walled, hollow, cylindricalt
synthetic plastic molded part. The slot, which
will be more fully described hereafter, permits
a unique placement and construction of the
captured tooth. Also, the take-up spool can
then take the forces built up therein when film
tension responsive means are incorporated in
the camera as previously described.
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The concept of providing a means for
positioning the take-up spool in a precise
optimum position, such as by an electric motor
drive responding to the opening the of the film
chamber door, is disclosed in above-identified
copending Canadian Patent Application Serial No.
450,121. This invention as shown
therein is applied to a half-frame, drop-in
loading camera. Unlike conventional 35mm full
frame cameras, the film cartridge and film
leader are inserted edgewise into small slots
and openings in the camera housing end wall,
and the user has no access to the film leader
once the cartridge is inside the camera. There
is also no full view of the take-up spool slot
to aid the operator to place the film leader
into the slot the slot opens the axial end of
the spool. When the take-up spool is properly
positioned, the film leader-receiving slot
automatically is aligned with another slot in
the camera end walls so that the film leader is
guided ther~by into the take-up spool slot upon
dropping of the film into the camera. The
automatic spool positioning means is here a
practical necessity. Thus, to provide an
automatic means for positioning the take-up
spool in a pre-determined position where the
poorly visible slot is aligned with the plane
of the end of the film leader would not
necessarily suggest such an automatic
positioning feature in a camera where the take-
up spool slot and film leader are fully visible
and accessible.
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In the preferred form of the
invention, when the film chamber door is opened
to fully expose the film chamber, the take-up
spool is automatically moved into its ideal
position. The user merely drops the cassette
into the cassette-receiving chamber and then
places the end of the film leader into the take-
up spool slot without other special threading
operations. On closure of the door, pressure
on the film leader is then such as to present
the film leader in an ideal position to be
captured by the hook on the take-up spool as
soon as khe take-up spool is advanced in a film
winding direction. Film advancement can be
automatically initiated by closure of the door
or by subsequent operation of the shutter
release button.
Other advantages and features of the
invention will become apparent upon making
reference to the specification, claims, and
drawings to follow.
Brief Description of Drawin~s
Figure 1 is a perspective view of a
bac~-loading 35mm camera with the back open
prior to loading and showing the take-up spool
film slot properly positioned for film
threading;
Figure ~ is a partial perspective
Yiew of the take-up spool of ~igure 1, and
additionally showing a sector cam affixed
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thereto and rotatably operating a feeler switch
according to the position of the take-up spool
with respect to the camera housing;
Figure 3 is a representative circuit
providing for automatic orientation of the take-
up spool attendant to opening the camera back
to the configuration indicated in Figur~ 1 by
selectively actuating associated internal
electric motor drive means;
Fig~re 4A is a cross section view
along the section lines 4A-4A indicated in
Figure 1 where the camera i5 oriented so that
the film compartment is open at the top of the
camera housing and showing the take-up spool
properly positioned for film loading;
. .
Figure 4B is a partial plan view o~
the take-up spool of Figure 1 in the vicinity
of the film-loading slot, also showing a film
leader proximate to the take-u~ spool jus~
prior to engagement therewith;
Figure 4C is a view of the camera
similar to that shown in Figure 4A, and showing
a film leader loosely hooked to the take-up
spool prior to closure of the camera door;
Figure 4D is a view similar to that
shown in Figure 4C after an initial partial
rotation of the take-up spool in a film-
advancing direction and;
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Figure 5 is an enlarsed view of the
central portions of Figure 4A.
Detailed Description of the Invention
Figure 1 shows an electrically
operated camera of generally conventional
design to which the teachings of the present
invention are applied. The camera lO feature~
a housing 12 having a cassette-receiving
chamber 16, a take-up spool 22, a pair of ilm
guide rails 1~, 20 integral with the housing
12, a film advance metering sprocket 30, a
pushbutton 28 serving to actuate the shutter
and to automatically initiate advance of a
subsequent film advance by electric motor drive
means (not shown), and an end-of-film switching
memb~r 32 for disconnecting the motor drive
system when the film leader has been rewound
clear of the take-up spool 22. Also shown is
hinged swing-open film compartment closure door
14 secured in a closed positi on by a latch l~
and carrying a customary pressure plate 36
which serves to flatten the film against the
guide rails 18 and 20 when the door is closed.
In particular, there are mounted in the housing
switch actuating members 34 and 32 configured
to be actuated responsively to opening or
closure of the door 14 by engagement with a
corresponding tang 38 or a shelf 40
respectively, each being integral with the door
14. The upper switch member 34 may be
associated with conventional switching reset
means for reconfiguring the electronic
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circuitry (not shown) of the camera from a rewind to a
forward film advancing configuration responsively to either
opening or closing the door 14. Switch member 32, similarly
responsively actuated by movement of the door 14 between
opened and closed positions, serves to actuate special drive
circuitry for driving the take-up spool 22 to present the
film leader loading slot 24 to be oriented properly outward
for the next film loading operation.
The take-up spool is shown as a thick-walled
cylinder 22 having an unusually wide film leader-receiving
slot 24 terminating at widely separated end walls 70, 72.
This slot and associate capture hook 26 are shown in detail
in Figure 2 and in Figures 4A-4D at various phases of the
capture process. Figure 4A shows the orientation of the
film loading slot 24 properly positioned for loading when
the camera housing is resting on its front wall so that
the film compartment open onto the top thereof. Figure
4B is a partial plan view of the take-up spool shown in
Figure 4) with the slot 24 similarly positioned, i.e. facing
directly outward from the housing 12. The film loading
slot 24 is configured only slightly longer than a width
of the leader end of a standard film 62 so that the end
perforations 64-64 thereon will be -~properly aligned with
respect to the capture hook 26 when the end is inserted
into the slot 24. With particular respect to the slot con-
figuration, and its relationship to the hori~ontal surface
of the guide rail 20 (see
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also Figure 1~, it will be noted that the slot
is defined in its long direction by two
inwardly extending walls 56, 58 hereinafter
referred to as the leading and trailing walls
respectively. The leading wall 56 is shown
extending in almost a vertical direction and is
formed by a substantially radial cut through
the relatively thick-walled take-up spool
cylinder 22 and accessing a cylindrical leader-
accepting interior chamber having a defining
interior wall 60. The trailing wall 58, on the
other hand, is disposed to lie generally
horizontally (and thus makes a substantial
angle to a radial line). Also it is out of
alignment with respect to the plane of the
captured film leader, so that at most only the
radially innermost portion of the trailing wall
58 contacts the film prior to initial advance
thereof.
The trailing wall 58 has near one end
thereof a locally ~ircumferentially extendiJ-Ig
hook 26 extending in a leading or film-
advancing direction therefrom. The outer
periphery 26a of the hook is a continuation o~
the cylindrical outer periphery of the take-up
spool and it terminates in a depending sur~ace
26c orming a film aperture capture point or
edge 26b. It will be noted that as viewed ~rom
directly above the loading slot 24 tFi~ure 4B),
the leading edge 26b of the hook 26 extends
only slightly beyond the rightmost projection
o~ the trailing wall. Figure 4C shows the film
leader extended beyond the position shown in
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~i~ure 4B so that the hook 26 captures one of
the perforations 64. Here the film is only
loosely extending over the guide rail 20, the
door not yet having been closed. It will be
further noted that the radially outermost
portions of the trailing wall 58 are not yet in
contact with the film 6~. Figure 5 shows a
portion of the spool 22 in more detail with
respect to this phase of capture.
Figure 4~ shows the orientation of
the take-up spool and the film after a modest
portion of initial film advance, and wherein
the entire trailing wall 58 has been brought
into contact with the proximate surface of the
film 62. Here it will be noticed that the film
is now fully engaged on the capture hook 26,
being fully flattened against the surface of
the trailing wall 58. A relatively thick-
walled take-up spool is provided to insure
adequate mechanical strength. It ~ill be
a~preciated that if the trailing wall 58 were
not so angled back with respect to the capture
region of the film as shown in Figure 4C, there
would be a strong likelihood that a
convent;onally radially oriented trailing wall
configured similarly to the leading wall 56
might well cam the film out of engagement with
the hook 26, thereby causing feeding failure
and loss of film.
Further, it will be not~d, with
particular respect to Figure 4B, that the
relative orientation of the leading and
13 ~ S
trailing walls 56, 58 provides a relatively
wide range of initial insertion angles of the
~ilm leadex; i.e. the orientation of the leader
need not be precise in order to secure reliable
film capture. Thus, the effective insertion
area of the take up spool 22 is raised, without
substantially impairing the structural
integrity of the take-up spool itself. Also
this geometry provides a secure anchoring for
the hook 26 over a distance substantially
greater than would be provided by a radially
disposed leading wall such as 56, since the
effective area of anchorage between ~he hook 26
and the trailing wall 58 is substantially
greater than the thickness of the annulus
defined between t~e outer surface of th~ take-
up spool 22 and interior wall 60 thereof. By
this means additional strength is imparted to
the take-up hook as well.
- With respect to the aforementioned
ta~e-up spool positioniny s~stem, Figure 2
shows in partial form the take-up spool 22
having mounting shafts 44, 46 affixed to
conventional bearing and drive means ~not
shown~ and further having a sector cam ~2
affixed to one end thereof. A sector 48 t
constituting an inward extension of a radial
portion of the outer sur~ace of the cam 42
slidingly engages an appropriately shaped
sensor blade 50 to drive the sensor blade in an
oscillatory motion between extreme positions
according to the orientation of the cam 42 as
- the take-up spool is rotated by the motor drive
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means. A sensor contact 52 is positioned to
confront the sensor blade 50, these two
contacts constituting elements of a switch S2
(see Figure 3). Rotation of the take-up spool
26 holds the sensor blade SO and the sensor
contact 52 in a closed condition thereby
completing the electrical circuit therebetween
until the take-up spool is rotated to the
appropriate position shown in Figure 1 (see
also Figure 4A), whereupon the sensor blade 50
springs to a circuit-opening condition.
Figure 3 shows a representative
circuit for automatically repositioning the
take-up spool 22 when the door 14 is opened
after rewind. A modified conventional motor
driven film advance control circuit is shown.
The conventional portions of this circuit are
represented by a film advance control circuit
FACC powered by a battery B and responsive
through actuation of switch S3 (responsively
coupled to pushbutton G~ ) to energize a relay
coil R for a predetermined period via line Ll,
which completes the circuit from relay coil R
~o the opposite side of battery B. The movable
contactor C of a single pole double throw relay
energized contacting system alternatively
throws a short circuit across the motor M
connected between terminals A and C of switch
S4 to brake film advancet or ~hen the contactor
C contacts terminal B, applies electrical drive
to the motor M from the battery B. Control of
the motor direction is controlled by a polarity
of reversing switch PRS having its switching
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state responsive to the internal switching
condition of the film advance control circuit
FACC. The film advancing control circuit FACC
is reset to the forward configuration by well-
known means according to the settings of the
end-of-film sensing switch associated with the
switch member 31 of Figure 1, and a door-
actuated switch SR operatively associated with
the door actuated switch member 34. A variety
of means are well-known in the art for
accomplishing such programmed reversa.l of the
motor drive polarity via the polarity switch
PRS according to these switch sensings.
With respect to the present
invention, upon termination of rewind, and with
the film advancing control circuit preferably
designed to set the polarity reversing switch
PRS to forward (advancing) polarity, opening
the camera door allows switch mem~er 32 to
close its associated switch Sl. In the event
that the slot 24 (Figure 2) is not properly
positioned, switch S~, corresponding to sensor
blade 50 and sensor contact 52, will be in a
ciosed-circuit condition. Thus, it will be
seen that one end of the coil of the relay R
will b~ grounded, resulting in the energization
of the relay to cause the movable contactor C
to contact terminal ~. This causes electrical
power to be delivered to the motor M from the
battery B. The take-up spool will therefore be
immediately energized to a forward direction,
rotation continuing until the cam sector 48
cause.s sensor blade 50 to move away from the
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sensor contact 52, thereby breaking this
circuit and terminating motor drive power. At
this point, the slot 24 is properly facing
outward form film insertion.
Thus, there has been described a
convenient and inexpensive system for reliably
threading the film into a 35mm (or similar~
camera having a swing-open back, and having all
of the advantanges of a narrow diame~er take-up
spool, and overcoming many of the principal
drawback~ thereof as previously outlined in the
Background Prior Art. 8y automatically
positioning a single slot in the take-up spool
at optimum position for accepting a film
leader, and by optimally positioning the
dimensions of the aperture itself, its defining
walls, and the capture hook thereon, a reliable
and inexpensive system is provided which allows
for an inexpensive solution to the problems
previously outlined.
While the invention has been
described with reference to a preferred
embodiment, it will be understood by those
skilled in the art that various changes may be
made and equivalents may be substituted for
elements thereof without departing from the
scope of the invention. In addition, many
modifications may be made to adapt a particular
situation or material to the teachings of the
invention without depar~ing from the essential
scope thereof. Therefore, it is intended that
the scope o~ ~he claimed invention not be
limited to a particular embodiment disclosed as the best
mode contemplated for carrying out the invention, but that
the scope of the claimed invention will include all embodi-
ments and equivalents falling within the scope of the general
principles disclosed herein.
Thus, for example, a great variety of sensing
means may alternatively be used in use of the cam-actuated
slot positioning switch previously described. Such variants
as a suitably placed commutator-type switch may equally
well be employed, as may a variety of other electrical sensing
means, including optical sensing means. Further, although
the present disclosure describes momentarily actuating the
motor drive circuitry to reorient the take-up spool by driving
the spool in a forward or film-advancing direction responsively
to switching circuitry actuated by opening the loading door,
clearly similar circuitry could readily be devised which
would respond to actuation of the end-of-film sensor which
terminates the rewind operation. Alternatively the door
latch 13 itself could be coupled to switching means (Sl' -
Figure 1) so that unlatching the door actuates the reorienta-
tion drive. The designation of the actuating switch in
Figure 3 as "Sl/Sl"' indicates that this switch may be placed
in either of the two locations. Moreover, once the film
has disengaged after rewind, the switching circuitry could
be adapted to continue the rewind drive of the take-up spool
until it is properly positioned. In short, switching means
responsive either to an end-of-film condition, or to operations
attendant to the opening of the camera door may
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be used to drive the take-up spool either in an
advancing or a rewinding direction to po~ition
tbe slot Eor the next loa~in operation.
