JPH0486640A - Film feeding mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a film feeding mechanism installed in an optical device such as a still camera, and particularly relates to a film feeding mechanism having a driven sprocket driven by the film. .

(Prior art) Known still cameras that use roll film include:
The camera is equipped with a sprocket that rotates in conjunction with the movement of the film, and this sprocket functions as a bridge member of the film movement amount detector and as a component of the film feeding mechanism.

The sprocket consists of a sprocket shaft rotatably supported by the camera body frame, and two sprocket wheels fixed to both ends of the sprocket shaft, and both sprocket wheels are in phase with each other ( In other words, the sprocket teeth were completely identical and had sprocket teeth provided at the same position along the circumferential direction.

FIG. 5 shows a known sprocket 5 as described above, in which 51 is a sprocket shaft, and 52 and 53 are attached to both ends of the sprocket shaft 51.
52a and 53a are teeth formed on the respective sprocket wheels 52 and 53.

(Problems to be Solved by the Invention) The conventional sprocket shown in FIG. 5 has the following problems.

When manufacturing the sprocket 5, it is inevitable that a slight difference e will occur in the positions of the teeth 52a and 53a of the sprocket wheels 52 and 53, which are in the same phase position, respectively, due to manufacturing errors, but such a difference e exists. For cameras equipped with sprocket 5, during film feeding,
When the teeth of each sprocket wheel 52 and 53 enter the perforation hole in the film, and when the sprocket leaves the perforation hole, the teeth are so far offset from the center of the half-omission hole that they contact the edge of the hole. As a result, (i) noise is generated, (ii) film feeding load increases, (if) resistance to film feeding increases significantly and film feeding stops, (
iv) When the ambient temperature is low (for example, -10 or lower), phenomena such as film breakage and accidents occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved film transport mechanism that is less likely to cause unwanted contact between the film and the sprocket teeth.

[Means for Solving the Problem] As mentioned above, the main cause of the sprocket teeth coming into contact with undesirable positions on the film is the difference e between the positions of the teeth of the same phase on each of the two sprocket wheels. It is something that happens.

In the present invention, in order to prevent the above-mentioned difference e from occurring, a cylindrical body or a cylindrical body having a smooth outer peripheral surface is provided at one end of the sprocket shaft instead of one sprocket wheel, thereby preventing the above-mentioned various phenomena from occurring. It is characterized by being able to prevent

[Function] In the film feeding mechanism of the present invention, a sprocket wheel having teeth that fit into the perforation holes on one side edge of the film is provided at one end of the sprocket shaft, and the other end of the sprocket shaft has a smooth outer peripheral surface. Since a cylindrical body (or cylindrical body) with No incorrect contacts occur.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

1 and 2 are diagrams for explaining a first embodiment of the present invention. In FIGS. 1 and 2, 1 is a camera body, 2 is a spool for winding film, and 3 is a sprocket. As shown in FIG. 2, the sprocket 3 has a sprocket wheel 32 at one end of a sprocket shaft 31, and a sprocket wheel 32 at the other end of the shaft 31.
A smooth cylindrical body 33 having an outer diameter the same as the diameter of the root circle of No. 2 is provided. A plurality of teeth 32a are protruded from the outer peripheral surface of the sprocket wheel 32 at the same pitch as the large perforation on one side edge of the film.

In a camera in which the sprocket 3 of this embodiment having the above-described structure is arranged as shown in FIG. 1, the teeth 32a of the sprocket wheel 32 enter and exit only into and out of each perforation hole at the lower edge of the film during film feeding. As long as the distance between the large-sized holes and the distance between the teeth of the word gap 32a are equal, forced contact between the word gap 32a and the film will not occur, and therefore, film feeding failure due to excessive film feeding load will not occur. There is no risk of noise caused by film cutting accidents or contact with film parts.

FIG. 4 shows a sprocket 4 in which a sprocket wheel 42 is fixed to the upper end of a sprocket shaft 41 and a smooth cylindrical body 63 is fixed to the lower end of the shaft 41. The same effects as those of the above-mentioned embodiments can be obtained even in a camera that uses a conventional camera. FIG. 3 shows a camera equipped with the sprocket 4 as a component of the film feeding mechanism.

It goes without saying that the distance between the teeth 42a protruding from the sprocket wheel 42 of the sprocket 4 is equal to the distance between the perforation holes of the film (not shown).

[Effects of the Invention] As explained above, the improved film feeding mechanism of the present invention is equipped with a sprocket to which a sprocket wheel is fixed only at one end. It is possible to prevent various phenomena caused by misalignment between another hole position and the sprocket tooth position, and the manufacturing cost of the film feeding mechanism including the sprocket is also lower than before. I can do it.

[Brief explanation of the drawing]

1 is a rear front view of a camera equipped with a film feeding mechanism according to the present invention; FIG. 2 is an enlarged perspective view of an embodiment of a sprocket as a component of the film feeding mechanism shown in FIG. 1; Figure 3 is a rear front view of a camera equipped with the sprocket shown in Figure 4, Figure 4 is an enlarged perspective view of the sprocket shown in Figure 3, and Figure 5 is an enlarged perspective view of a conventional sprocket. , is. 1...Camera body 2...Spool 3.4.
5... Sprocket 31.41.51... Sprocket shaft 32, 42.5
2.53... Sprocket wheel 32a, 42
a, 52a, 53a, ... tooth 33.43.
...Smooth cylindrical body and 4 others Figure 2 Figure 1 Figure Figure

Claims (1)

[Claims] 1. In a film feeding mechanism having a sprocket that rotates in conjunction with the movement of the film, a sprocket wheel is fixed to one end, and a sprocket wheel is fixed to the other end with a diameter equal to the diameter of the root circle of the sprocket wheel. A film feeding mechanism characterized by comprising a sprocket shaft to which a smooth cylindrical body or a smooth cylindrical body having an outer diameter is fixed.