JP2787439B2 - Film holding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film holding device for a camera having a mechanism for measuring and controlling a film feed amount by a photoelectric detector or the like. 2. Description of the Related Art Some motor-driven compact cameras loaded with a 35 mm film film use a photo sensor to count the number of film perforations passed by a photo sensor instead of one-frame feed control by a driving sprocket. 2. Description of the Related Art There is known a camera in which film single-frame feed control is performed based on a count value. In such a camera, the film is fed by the take-up spool drive, and the rotation of the motor driving the take-up spool is stopped by the count signal from the photo sensor. Further, in the pre-winding type camera, the loaded film is all wound in advance on a take-up spool, and each time one frame is photographed, the patrone shaft is driven to rewind the film into the patrone one frame at a time. However, as described above, in the case of a camera that performs single-frame feed control of a film without using a driving sprocket, a mechanical interlocking mechanism from the motor to the driving sprocket can be omitted. On the other hand, there is a disadvantage that the frame intervals are likely to be uneven. That is, in a camera using a drive sprocket, the drive sprocket is always engaged with the perforation, so that accurate film one-frame advance can be achieved simply by controlling the drive of the drive sprocket. With a camera that does not have a mechanism to mechanically prevent the movement of the film after one frame of film has been fed, when the film feed motor is stopped, only the film will be slightly idle, This is because, when vibration is applied to the camera, the film is loosened in the patrone or from the winding spool of the camera, and the film slightly moves behind the aperture. To prevent this, a load may be applied to the film so that the film does not easily move. However, if such a configuration is simply adopted, when the film is continuously fed, That is, when a film is rewound by a normal camera or when a preliminary winding is performed by a preliminary winding type camera, the film feeding load is increased, which is disadvantageous in terms of power consumption. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks. The present invention has been made in consideration of the above-described drawbacks. It is an object of the present invention to provide a film holding device in which the feeding load is not increased when the film is fed. SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides, apart from a pressure plate for pressing a film from behind on a film receiving surface on which an aperture is formed, a back surface of the film outside an effective exposure range. Is elastically pressed against the film receiving surface by the elastic film pressing portion. That is, in one embodiment of the present invention, a camera that includes a pressure plate for pressing the film from the back surface toward the film receiving surface on which the aperture is formed, and that does not use a driving sprocket for the film feeding means, is provided separately from the pressure plate. There is provided a film pressing means for pressing the back surface of the film toward the film receiving surface outside the effective exposure range determined by the aperture, and the film pressing means has one end fixed to the camera back lid side and the other end. It is a cantilevered leaf spring provided with a film pressing portion abutting on the back surface of the film, and this leaf spring has an end portion on the upstream side when the film is continuously fed, and the film pressing portion holds the film. The film holding section is arranged so as to be located on the downstream side when continuous feeding is performed, and the film holding section is provided at least when film feeding is stopped. Provided at a position in contact with the back of the. According to another aspect of the present invention, there is provided a camera having a pressure plate for pressing a film from a back surface toward a film receiving surface having an aperture formed therein and using no drive sprocket as a film feeding means. Separately, film holding means for holding the back of the film toward the film receiving surface outside the effective exposure range determined by the aperture is provided, and the film holding means has one end fixed to the camera back lid side, The other end is a cantilevered leaf spring provided with a film pressing portion abutting on the back surface of the film, and the leaf spring is provided on the upstream side when the one end portion continuously feeds the film. The pressing portion is arranged so as to be located on the downstream side when the film is continuously fed, and the film pressing portion is provided with a perforation. It is provided in contact with the back surface of the film in the area not. The direction of one-frame film feeding and the direction of continuous film feeding always have the opposite relationship. Therefore, by devising the shape of the film pressing spring urging the film pressing portion as described above, the urging force of the film pressing spring can be made to work strongly or weakly in accordance with the film feeding direction. This makes it possible to prevent the frame intervals from becoming irregular without increasing the load during continuous film feeding. Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a perspective view of a camera using the present invention when viewed from the inside, and FIG. 2 is a view of the camera using the present invention taken along a film feeding direction. It shows a cross section of a main part. In FIGS. 1 and 2, an aperture for defining an exposure area for one frame of a film is formed on a film receiving surface 2 formed on a camera body 1, and as shown in FIG. First, an effective exposure range 4 is defined on the film 3, and photographing is performed in this range. A well-known film rail and pressure plate rail are formed on the film receiving surface 2. The pressure plate 5 is attached to the back cover 7 via a pressure plate spring 6, and the front surface of the pressure plate 5 contacts the pressure plate rail. Then, the film 3 is passed through a gap (tunnel interval) formed between the film rail and the front surface of the pressure plate 5. The feeding direction of the film 3 is as shown in FIG.
In the figure, the direction is the left-right direction. Note that this camera is a prewinding camera that does not use a driving sprocket for film feeding. Immediately after the film is loaded, the film 3 is continuously fed rightward in FIG. 2 (to the left in FIG. 1). The entire length of the film 6 is wound on the winding spool of the camera. Each time a picture is taken, a motor drives a patrone shaft that is rotatably built into the patrone, and the photographed film 3 is wound around the patrone one frame at a time. The back cover 7 is provided with bosses 7a at two places, and the above-mentioned pressure plate springs 6 are fitted into the bosses 7a. The pressure plate 5 is provided with openings 5a and 5b having recesses. The bosses 7a are loosely inserted into the openings 5a and 5b, and screws 9 for preventing the boss 7a from being screwed into ends of the respective bosses 7a. Is being worn. A plate-shaped film pressing spring 10 is formed integrally with the pressure plate spring 6 along the feeding direction of the film 3. This film holding spring 10
The front end portion extends from the upstream side to the downstream side when the film 3 is continuously fed, that is, toward the pre-winding direction, and a roller 12 is attached to the front end portion by a shaft 11. Since the pressure plate spring 6 has a biasing force in a direction in which the front end thereof presses the rear surface of the film 3, the roller 12 projects toward the film 3 through the opening 5 c of the pressure plate 5. As shown in FIG. 2, a recess 13 is provided on the receiving surface 2 corresponding to the roller 12. Therefore, the film 3 is sandwiched between the roller 12 and the recess 13. As a result, as shown, the film 3 is slightly deformed so as to enter the recess 13. Then, when the film 3 is fed in the winding direction (the direction of one frame feed after photographing), a pressing force in the feed direction of the film 3 is applied to the tip of the film holding spring 10. This pressing force acts in a direction in which the leading end of the film pressing spring 10 bites into the recess 13, so that the film pressing spring 10 effectively presses the rear surface of the film 3 via the roller 12, and Give the load. On the other hand, the film 3 is a film holding spring 1
When the film is fed in the direction in which the leading end of the film holding spring 10 is oriented, that is, in the pre-winding direction, the pressing force from the back of the film received by the leading end of the film holding spring 10 causes the leading end of the film holding spring 10 to rise from the recess 13. Acts in the direction. Therefore, the load on the back surface of the film 3 during the preliminary winding is smaller than that during the winding. A contact piece 15 is disposed behind the roller 12, and the contact piece 15 is held by a support member 16 fixed to the wall surface of the back cover 7 and made of non-conductive plastic or the like. A conductor 17 is connected to the contact piece 15 via a support member 16, and is connected to a circuit for detecting the presence or absence of the film together with the conductor 18 connected to the pressure plate spring 6. That is, the tip of the film holding spring 10 and the contact piece 15 are usually separated by a fixed distance, but when the film 3 is loaded, the rollers 12 are pressed down and come into contact with each other. Circuit 3 is short-circuited
Is confirmed. The operation of the above embodiment will be described. When the film 3 is loaded into the camera body 1 and the back cover 7 is closed, the film 3 is sandwiched in a tunnel space formed by the pressure plate 5 urged by the pressure plate spring 6 and the film receiving surface 2. At this time, the roller 12 urged by the film holding spring 6
Presses the outside of the effective exposure range 4 of the film 3 in the direction from the back cover 7 toward the film receiving surface 2. In addition, due to this reaction, the leading end portion of the film holding spring 10 behind the contact piece 15 and the roller 12 that has been separated comes into contact with the contact piece 15, and the presence of the film 3 is confirmed, and preliminary winding is started. As described above, the plate-like film pressing spring 10 is formed along the feeding direction of the film 3, and the leading end is extended in the pre-winding direction in which the film 3 is continuously fed. The urging force of the film pressing spring 10 is reduced by the pressing force received from the back surface of the film 3 during the continuous feeding, and the feeding load of the film 3 is reduced. When the preliminary winding is completed, the shutter is charged and the preparation for photographing is completed. When shooting is performed by releasing the shutter, a feeding motor (not shown) is driven in the camera body 1,
The patrone shaft built in the patrone rotates in the film winding direction. Thus, one-frame film feeding is started. When the number of perforations 3a reaches an appropriate number by a photo sensor (not shown), a stop signal is generated, the driving of the feeding motor is stopped, and one frame feed is completed. By the way, at the moment when the feeding motor is stopped, inertia acts, for example, the patrone shaft slightly rotates in the same direction by the amount of backlash, and the film 3 often moves accordingly. However, since the roller 12 urged by the film pressing spring 10 comes into contact with the back surface of the film 3 to apply an appropriate load, the film 3 does not move due to the influence of the inertia described above. Further, even when the feeding of the film 3 is stopped, since the load is applied to the film 3 by the pressing of the roller 12, the film 3 moves due to the influence of vibration applied to the camera body 1 and the screen interval becomes uneven. Nor. The roller 12 used in the above-described embodiment is omitted, and the leading end of the film holding spring itself forms the film 3.
FIG. 3 shows an embodiment in which is pressed. Note that the same reference numerals are used for members common to the above-described embodiment. In this embodiment, the distal end of the film holding spring 20 is bent as shown in the figure, and the contact surface with the back surface of the film is rounded. The function of this contact surface is exactly the same as that of the roller 12 of the above embodiment. The front end bent toward the back cover 7 serves as a film detection switch for checking the presence or absence of the film 3 by pairing with a contact piece 15 provided behind the front end. As described above, according to the film holding device of the present invention, apart from the pressure plate, the film holding unit is pressed against the back surface of the film outside the effective exposure range.
The film pressing spring for urging the film pressing portion is formed in a plate shape so as to be along the film feeding direction, and the tip end of the film pressing portion which is urged is directed to the downstream side during continuous feeding of the film. As a result, an appropriate load is applied to the film at the time of feeding one frame of the film to prevent the frame intervals from being irregular, and the load is not increased at the time of continuous feeding of the film, so that the power supply is wasted. No wasting. In addition, if the film holding spring is formed integrally with the pressure plate spring, the number of parts can be reduced, the number of assembling steps can be rationalized, and the present invention can be implemented at low cost. Further, since the film holding spring takes a different position depending on the presence or absence of the film, the switch can be turned on and off by this, so that it can also be used as a means for detecting the presence or absence of the film.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an inner surface of a back cover of a camera using the present invention. FIG. 2 is a sectional view of a main part of a back cover part of the camera shown in FIG. FIG. 3 is a cross-sectional view of a main part of a back cover part of a camera using another embodiment of the present invention. [Description of Signs] 2 film receiving surface, 3 film, 5 pressure plate, 6 pressure plate spring, 7 back cover, 10 film pressing spring, 12 rollers.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-218433 (JP, A) JP-A 50-89331 (JP, U) JP-A 63-180839 (JP, U) 43702 (JP, U) Jiko 6-6332 (JP, Y2) (58) Fields studied (Int. Cl. ⁶ , DB name) G03B 17/28 G03B 1/48

Claims (1)

(57) [Claims] A camera having a pressure plate for pressing the film from the back surface toward the film receiving surface on which the aperture is formed, and in a camera that does not use a driving sprocket for the film feeding means, separately from the pressure plate, the effective exposure range determined by the aperture. Film holding means for holding the rear surface of the film toward the film receiving surface outside is provided, the film pressing means having one end fixed to the camera back lid side and the other end contacting the rear surface of the film. The leaf spring is provided at one end thereof at an upstream side when the film is continuously fed, and at a downstream side when the film holding section continuously feeds the film. The film pressing portion is provided at a position such that the film pressing portion is in contact with the back surface of the film at least when the feeding of the film is stopped. Film hold-down device, characterized in that. 2. In a camera that includes a pressure plate that presses the film from the back toward the film receiving surface on which the aperture is formed, and that does not use a driving sprocket in the film feeding means, separately from this pressure plate, the effective exposure range determined by the aperture Film holding means for holding the back of the film toward the film receiving surface outside is provided, and the film holding means has one end fixed to the camera back cover and the other end abutting against the back of the film. Portion is a cantilevered leaf spring, the leaf spring is located on the upstream side when the one end portion continuously feeds the film, when the film pressing portion continuously feeds the film. The film holding portion is disposed so as to be located on the downstream side, and the film holding portion contacts the rear surface of the film in a region where the perforation is not provided. Film hold-down device, characterized in that provided on so that.