Camera with guiderails shaped to provide film flatness in the im

Photography – With film drive – Mechanical detail

Patent

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Details

396440, 396535, G03B 100, G03B 1700

Patent

active

058782974

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a camera, and more particularly, to a camera to which a photographic film cartridge that is of a photographic film feed type and that has a structure for preventing loose film wind is adapted.


BACKGROUND ART

In the past, photographic film cartridges disclosed in U.S. Pat. No. 5,251,840 and Japanese Unexamined Patent Publication No. 5-45801 have been known as photographic film cartridges capable of feeding photographic film stowed in a cartridge when the photographic film cartridge is loaded in a camera.
In the conventional photographic film cartridge, flanges molded using a flexible raw material are engaged with both ends of a spool, about which photographic film is wound, within the cartridge. Juts of annular tongues molded unitedly along the margins of the flanges are used to wrap part of the outermost circumference of the photographic film wound about the spool from both ends of the film. Thus, loose wind of photographic film is prevented.
When the spool is rotated in a feed direction, the photographic film rotates together with the spool without being wound loosely. In the vicinity of a film port of a cartridge body, the photographic film is fed outside while thrusting the juts in a film-width direction.
The details of the structure of the foregoing conventional photographic film cartridge, and the film feed operation will be described in conjunction with the sectional view of a cartridge of FIG. 7 and the view showing a film feed path of FIG. 8 in which a camera in which film feed is under way is viewed from behind.
In a cartridge 101, photographic film 102 is, as shown in FIG. 7, stowed in a cartridge body 101a and wound about a spool 103 in the cartridge body 101a. Flanges 105 and 106 molded using a flexible raw material are respectively engaged with opposite ends of the spool 103 in the cartridge. Annular juts 105a an 106a, for preventing loose winding of the film 102, are formed unitedly along the outer margins of the flanges 105 and 106.
The film 102 fed from the cartridge 101 having the foregoing structure to a camera passes, as shown in FIG. 8, behind a photographic aperture 108 of the camera and is then wound about a spool 107 in the camera. At this time, the annular juts 105a and 106a of the flanges 105 and 106 are elastically deformed to be thrust in a width direction of the film in the vicinity of a film port 104 by means of the film 102. The annular juts 105a and 106a thus apply respectively pressing forces F and F' to the film. The deformed portions of the juts 105a and 106a are denoted by reference numerals 105b and 106b. A perforation 102a is formed by piercing the film 102 at given intervals along one edge of the film 102 in the width direction thereof.
When the conventional photographic film cartridge 101 is employed in a camera, as mentioned above, the film 102 receives the pressing forces F and F' resulting from elastic deformation of the flanges 105 and 106 in the vicinity of the film port 104. If the camera is left intact in this state for a long period of time, the film 102 undergoes deformation, which disables the film from being reset soon, because the pressing forces F and F' have operated on the film for the aforesaid long period of time.
FIGS. 9 and 10 show a section of the film in the width direction thereof. FIG. 9 shows the section of the film in a normally curled state in which the film does not receive the pressing forces F and F'. FIG. 10 shows a curled state of the film after the film has received the pressing forces F and F' shown in FIG. 8 for a prolonged period of time.
In FIGS. 9 and 10, the emulsion-coated side of the film 102 is denoted by reference numeral 102b. In general, the photographic film 102 has a curling characteristic that the emulsion-coated side 102b becomes concave. As shown in FIG. 9, the magnitude C1 of a curl in the normally deformed state is within a given range. As shown in FIG. 10, the emulsion-coated side 102b of the film 102 having received the pressing forces F and F' for a prolonged per

REFERENCES:
patent: 1957904 (1934-05-01), Ord
patent: 2192692 (1940-03-01), Nerwin
patent: 3387546 (1968-06-01), Winkler et al.
patent: 4933693 (1990-06-01), Beach
patent: 5097278 (1992-03-01), Tamamura et al.
patent: 5251840 (1993-10-01), Niedospial

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