Photography – With film drive – Having significant electronic circuit detail
Reexamination Certificate
1997-11-14
2001-01-16
Lee, Eddie C. (Department: 2851)
Photography
With film drive
Having significant electronic circuit detail
C396S408000, C396S409000
Reexamination Certificate
active
06175696
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a camera capable of sensing a film jam.
2. Description of the Related Art
A well-known type of patrone is loaded in a camera in a state where the leading end (leader) of a film protrudes therefrom. In general, when the patrone is set in a patrone chamber, the leader is drawn out to a take-up spool and a rear cover of the camera is closed, automatic loading of the film is started to take up the film. At this time, if the amount of the leader to be drawn out is too large or too small, automatic loading ends in failure, or the film is inadvertently overdrawn and exposed to light. Furthermore, when prints are obtained from an exposed and developed film (negative or positive), particularly by an automatic printing machine, they may be contrary to the intention of the photograph since the photographing conditions are not known to a photo laboratory.
Accordingly, there has recently been proposed a new type of film and film cartridge.
FIG. 3
is a perspective view showing a cartridge chamber
14
of a camera using such a film, and a cartridge
10
. A leading portion (leader) of the film is completely wound in the cartridge
10
without protruding outside. When the cartridge
10
is inserted in the cartridge chamber
14
of the camera, a cover (not shown) of the cartridge chamber
14
is closed for shading.
FIG. 6
is a perspective view showing the states of the cartridge
10
and the film inside the camera. Numerals
13
,
19
a
,
19
b
. . .
21
a
, and 16 to 18 respectively denote a film, perforations previously provided on the film, and frame areas to be exposed which are so defined corresponding to two perforations as illustrated that an image is formed therein. The film leader does not protrude from the cartridge
10
before loading as shown in FIG.
3
. When the cartridge
10
is loaded in the camera, a fork
15
is rotated by a motor in an extruding direction (in the clockwise direction in
FIG. 3
) to rotate a spool
23
in the cartridge
10
, by which the film
13
is extruded from the cartridge
10
. This motion for extruding the film
13
from the cartridge
10
is referred to as “thrusting”. Areas
24
to
26
capable of magnetic recording are provided for their respective frames, and can record in the exposed frame which the type of light source, exposure value, the date and the like.
This type of cartridge is provided with a disc, referred to as “data disc”, on which the type of the film, the number of frames to be exposed and the ISO speed are recorded in a bar code.
FIG. 4
is a plan view of a data disc
22
, and
FIG. 5
is a longitudinal sectional view of a part of the cartridge
10
adjacent to the data disc
22
. The data disc
22
is fixed on the spool
23
to rotate in a one-to-one relation to the rotation of the spool
23
. A photoreflector
3
is placed at a position shown in
FIG. 5
, and information on the data disc
22
is read based on signals from the photoreflector
3
while rotating the fork
15
in the rewind direction.
The use of the above-mentioned type of film eliminates the disadvantages of the prior art.
When the cartridge is loaded in the camera, the film wound in the cartridge is thrust and slid between a pressure plate and a guide rail. The film leader, which has reached the take-up spool in the camera, is wound on the take-up spool and the film is taken up in correlation to the rotation of the take-up spool. This automatic loading ends in response to sensing of the first frame. During thrusting, the film may be caught somewhere (referred to as “jammed”), which results in loading failure.
U.S. patent application Ser. No. 670278/1991, now U.S. Pat. No. 5,521,667, suggests reducing the time taken to recover from loading failure by detecting a jam from the change in film transport speed by using a film transport speed detector located near an aperture, once rewinding the film when the jam occurs while the film is being thrust, and restarting thrusting of the film before the film is completely wound in the cartridge.
However, realization of the above suggestion requires the film transport speed detector, which increases the size and cost of the camera.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a camera comprising a measuring construction for measuring the thrust amount of a film from a film cartridge, and a sensing construction for sensing the position of a leader portion of the film, wherein the camera judges that a jam has occurred when the measuring construction measures a predetermined thrust amount of the film and the sensing construction does not sense that the leader portion of the film has moved to a predetermined position.
Accordingly, it is possible to detect a jam simply and accurately.
REFERENCES:
patent: 5255034 (1993-10-01), Shimada et al.
patent: 5398090 (1995-03-01), Ezawa
patent: 5467155 (1995-11-01), Miyazaki et al.
patent: 5521667 (1996-05-01), Egawa et al.
patent: 5548359 (1996-08-01), Wakabayashi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Lee Eddie C.
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