JPH0441328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film autoloading device for a camera, and more particularly to an autoloading device that automatically winds a film onto a spool by friction between the outer periphery of the spool and the film.

Traditionally, the film is fed by a sprocket,
Many attempts have been made to simplify film loading by automatically winding the fed film onto a spool. Among these methods, the method of pressing the film against the spool's outer circumference with a roller and using the frictional force between the spool and the film to pull the film around the spool is superior to other methods in terms of simple structure and reliable film tension.

However, in this method, it is difficult to regulate the vertical position of the film, especially at the leader section at the film's tip. It is easy for the spool to bite into the spool and form a loop that is larger than the spool's outer circumference. If this phenomenon occurs, the subsequent film winding diameter will increase significantly, and there is a risk that the film will come into pressure contact with the spool chamber wall before the entire film is wound, making subsequent winding impossible.

In order to prevent this phenomenon, the leading edge of the film must be at the ideal position in the width direction of the film determined by the guide rails above and below the aperture and the teeth of the sprocket, or the leading edge must be at the ideal position as shown in Figure 1. It is desirable that it be located at a certain level (indicated by a in the figure) below the position. Shifting the leading edge of the film below the ideal position in this manner will be referred to as skewing.

However, if the offset amount is too large, the following film will be wound at an angle, and the film will gradually move upward, resulting in the so-called bamboo shoot phenomenon. When this phenomenon occurs, there is a risk that the film will rub against the upper wall of the spool chamber, making it impossible to wind the film.

In order to solve these problems, we provided a protrusion on the film guide member that forced the film to one side, made the lower part of the spool thicker than other parts, and held the film at the bottom using the principle of a central pulley. JP-A-55-156928 proposes a device in which a flange is provided on the lower side of the spool to prevent the amount of shifting from increasing to a certain extent. Also special request in 1982
In No. 58047, the driving force from the spool and roller is generated upward from near the center of the film width, and the difference in the driving force between the top and bottom forces the film downward.

However, in the former case, the amount of offset is forcibly determined by the flange, so depending on the winding pattern of the film leader, even though a certain amount of offset has occurred in some places, the tip may be re-aligned. There is a possibility that it will spring up downward and get caught in the subsequent perforation, or that a bamboo shoot phenomenon will occur even though the amount of shifting is small. This is due to differences in properties between film manufacturers and changes in properties under high and low temperatures, and it is extremely difficult to determine the best point for the amount of biasing.

In the latter case, although the amount of shifting is free, there is no means to prevent the occurrence of the bamboo shoot phenomenon.

The present invention solves the above-mentioned drawbacks of the prior art, and provides an autoloading device that can sufficiently shift any film to one side and prevent the bamboo shoot phenomenon.

The present invention will be explained in detail below with reference to embodiments shown in FIGS. 2 to 6.

In FIG. 2, 2 is a camera body, 3 is a film take-up spool, and 4 is a film feed sprocket. Reference numeral 5 denotes an openable and closable back cover which is pivotally connected to the camera body via a shaft 5a, and rollers 6 and 7 are rotatably supported by the back cover. Reference numeral 8 is a guide plate which is pivotally supported on the camera body by a shaft 8a and which receives the leading edge of the film.
is held rotatably and biased counterclockwise by a spring (not shown) to move the roller 10a to the spool 3.
It is designed to be pressed against the outer periphery of the Reference numeral 9 denotes a film guide plate provided on the side near the sprocket, which is pivotally supported on the camera body by a shaft 9a, rotatably holds rollers 11a, 11b, and 11c by a shaft 11, and is supported by a spring (not shown). The roller is energized in the direction of pressing against the spool.

As is well known, the spool 3 and the sprocket 4 are connected by a gear and friction mechanism, and the circumferential speed of the spool 3 is set to be greater than that of the sprocket 4.

As shown in FIG. 3, a flange portion 3a is formed at the upper end of the spool 3, and a rubber 13 is wound around the outer periphery of the spool as a high friction member. The roller 10a is provided at a position that presses the upper edge of the film leader section approximately in the center of the film width against the rubber 13, and the rollers 11a and 11c are provided at positions corresponding to the upper and lower perforations of the film. is provided at a position corresponding to the above 10a. The lower roller 11c is larger than the other rollers 11a and 11b, and the film is pressed against the rubber 13 by the roller 11c.

Next, the operation of the above configuration will be explained.

As shown in FIG. 2, when the camera starts winding with the film 12 loaded in the camera, an unillustrated mechanism causes the sprocket 4 and spool 3 to move in the direction of the arrow while maintaining the above relationship. Rotate.

Since the perforation of the film meshes with the teeth of the sprocket 4 and is pressed against the sprocket by the rollers 6 and 7, the film is pushed out from the position shown in the figure toward the spool, and its tip is guided by the guide plate 8 and pushed onto the roller 10a. and spool 3. The state at this time is shown in FIG.

As mentioned above, the circumferential speed of spool 3 is
However, the feed amount of the film is determined by the sprocket, and the frictional force between the film and the rubber 13 of the spool is stronger than the frictional force of the friction mechanism, so the friction mechanism slips and the spool 3 Sprocket 4 can only rotate as much as it feeds the film. At this time, the film is pulled in opposite directions by the sprocket 4 and the spool 3 with a force corresponding to the frictional force of the friction mechanism.

The arrow 14 in FIG.
0a and the spool 3, and the arrow 15 indicates the force applied by the sprocket 4 to the film 12.
is the force applied to the perflation of At this time, only the lower perforation of the film is still hooked to the sprocket 4, so a couple of forces are applied to the film 12 by the above-mentioned forces 14 and 15, and in this state, the film is As 12 is fed, its tip points downward as shown by the broken line. This downward force continues until both the upper and lower perforations of the film engage the teeth of the sprocket.

Furthermore, the tip of the film 12 advances along the inner wall 2a of the spool chamber shown in FIG.
pushed between. This state is shown in FIG.
Since the film was guided to the inner wall of the spool chamber as described above, it was wound loosely around the spool 3 as shown in the figure.

At this time as well, since the leading edge of the film is in a downward state, it is driven by the roller 11c and the spool 3.
Therefore, the leading edge of the film 12 is fed out without being bitten into the perforation.

Further, the leading edge of the film is guided by the succeeding film and pushed between the succeeding film and the spool 3 at the roller 10a. In this state, the friction generated between the film tip and the spool 3 is greater than the friction between the films, so slippage occurs between the films, and the peripheral speed of the spool 3 becomes greater than the peripheral speed of the sprocket 4 again. Therefore, the film that was loosely wound around the spool 3 gradually comes into close contact with the spool. At this time, since the leading end of the film is facing downward and the trailing part is moving straight, a part of the film is bent and lifted upward while being in close contact with the spool.

If the amount of shifting is large, the amount of lifting of the film will also be large, causing the bamboo shoot phenomenon and the above-mentioned disadvantages.However, in the present invention, since the amount of lifting of the film is regulated by the flange 3a at the upper end of the spool, the amount of lifting of the film becomes large. The film does not lift to the extent that this phenomenon occurs.
Since the succeeding film advances straight, a stable winding condition is achieved as shown in FIG.

Note that the size of the spool flange does not need to be that large;
The amount of protrusion for three sheets is sufficient.

Further, in this embodiment, the roller 10a is located approximately at the center in the width direction of the film, but by lowering the roller 10a, the magnitude of the above-mentioned couple is reduced and the amount of biasing is also reduced, so the amount of biasing can be adjusted appropriately. Adjustment is also possible.

As described above, according to the present invention, the couple is used to shift the tip of the film downward only at the initial stage when the film leader is at the sprocket position. It is possible to prevent the tip of the section from biting into the perforation, and the subsequent film can be wound in a stable state.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the film being shifted to one side;
Figure 2 and subsequent figures show examples of the present invention. Figure 2 is a cross-sectional view of the film winding section, Figure 3 is a longitudinal cross-sectional view of the spool and roller section, and Figure 4 is a film winding section using a sprocket and roller. FIG. 5 is a perspective view showing the state in which the film has gone around the spool, and FIG. 6 is a front view showing the state at the start of close winding of the film. 1: Film, 2: Camera body, 3: Spool, 4: Sprocket, 5: Back cover, 6, 7: Roller, 8, 9: Film guide plate, 10, 11: Roller, 12: Film, 13: Rubber.

Claims (1)

[Claims] 1. A film autoloading device comprising a spool having a cylindrical outer periphery made of a high-friction member and at least two guide plates for guiding the leader portion of the film in the circumferential direction of the spool. In the camera, a flange portion is provided at the top of the spool, and a guide plate that the leader portion of the film first reaches is a guide plate that presses the film onto the spool, and a flange portion near the upper edge of the leader portion. a roller member that presses the film, and a sprocket that engages perforations at both upper and lower ends of the film and pushes the film toward the spool at least when the film is wound around the spool; The sprocket is interlocked with the film through a friction mechanism that is smaller than the frictional force between the film and the spool, and the circumferential speed of both is set so that the spool has a larger peripheral speed than the sprocket. The roller member and the sprocket are positioned so that even when the leader portion of the film is pressed against the spool by the roller member, the leader region is pushed out by the sprocket. A camera having an automatic film loading device, characterized in that when the leader section is pushed between the roller member and the spool, the leader section is directed downward by a force couple.