JPH04314042A - Film feeding amount detecting device for camera - Google Patents

Abstract

PURPOSE:To prevent useless load in film feeding from being imposed while making the diameter of a sprocket small and making a camera compact. CONSTITUTION:A roller member 3 which is pressed to a film surface and rotated by receiving driving force with the feeding of a film 2 by frictional force, and a sprocket 7 which is coaxially constituted with the roller member and formed to have a first rotating range where it rotates in a state where a tooth part engages with a perforation and a second rotating range where it rotates in a state where the tooth part does not engage with the perforation in the case of feeding one frame of the film are provided, then an elastic member 12 which connects the roller member 3 with the sprocket 7 and which generates smaller frictional force than that between the roller member and the film surface is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a film advance detection device for a camera using a film having a large pitch of perforations (at least one per screen).

0002

2. Description of the Related Art In conventional cameras, there are the following film feed amount detection means for feeding film by a fixed length.

1) A sprocket with teeth that mesh with the perforations of the film is used, and the amount of rotation of the sprocket as the film is fed is detected by a pulse plate, etc. 2) A roller pressed against the film 3) A device in which the amount of rotation of the roller member accompanying film feeding is detected by a pulse plate, etc. 3) A device in which the perforation of the film is detected by a photoreflector, etc.
However, in 1) to 3) above,
It had the following drawbacks.

First, 1) will be explained using FIG. 11. In FIG. 11, the pitch of the perforation P (this corresponds to the pitch of one frame of film) is L, the radius of the bottom circle excluding the tooth 101a of the sprocket 101 is B, and the tooth of the tooth 101a is If the length is A, the outer diameter of the sprocket 101 is "A+B", but "A+B"
must satisfy at least the relationship (A+B)2≧B2+(L/2)2. From this,
The outer diameter of the sprocket 101 is "L/2" or more. Therefore, if a film with a large pitch L of perforations P is used, the sprocket 101 will become large.

[0005] In 2), errors occur due to slippage between the roller and the film, and as a result, they accumulate, resulting in large errors.

[0006] In the above-mentioned method 3, the cost of the camera increases because it is necessary to include a photodetector element such as a photoreflector and its driving circuit. Moreover, the camera control circuit for controlling them becomes expensive and complicated. Furthermore, since the film feed amount cannot be output mechanically,
It is not possible to use a mechanical counter to measure the number of film frames, but a counter using a liquid crystal display or the like must be used, which also increases the cost of the camera.

[0007] Therefore, the applicant of the present application has proposed a method that can eliminate each of the above-mentioned drawbacks: ``A roller member that is pressed against the film surface and rotates by receiving a driving force as the film is fed by frictional force. , which rotates integrally with the roller member, and whose teeth engage with the perforations of the film when feeding one frame of the film, and which rotate while engaging with the perforations of the film. and a sprocket having a shape that has a second rotation range that rotates with the teeth not engaging the perforations,'' was filed on the same day. .

[0008]

[Problems to be Solved by the Invention] By providing a device configured as described above, it is possible to prevent errors in film feed amount and complicated circuit configurations, and to prevent Since the diameter of the camera can be made small, the camera can be made compact, and it can be said to be a very effective device. However, in the above structure, the roller member is at rest when the teeth of the sprocket are sliding on the film, so the roller member is also sliding on the film.
Since this amount of frictional force caused a loss in the film feeding force, the applicant of the present application has devised a new device to solve this problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a film feed amount detection device for a camera that can prevent unnecessary film feeding loads, reduce the diameter of a sprocket, and make the camera more compact. It is to be.

0010

SUMMARY OF THE INVENTION The present invention provides an elastic member that connects a roller member and a sprocket and generates a frictional force smaller than the frictional force between the roller member and the film surface.

[0011]

[Operation] The elastic member connects the roller member and sprocket by generating a friction force that is smaller than the friction force between the roller member and the film surface. - In the second rotation range where the roller member rotates without engaging the foration, the coupling force between the roller member and the sprocket is lost, and only the roller member can rotate due to the frictional force with the film surface. I have to.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show a first embodiment of the present invention. FIG. 1 is a perspective view showing the main structure of the present invention, and FIG. 2 is a sectional view thereof.

In these figures, 1 is a film cartridge, and 2 is a film having perforations 2a and 2b. In this embodiment, in order to explain this feature in an easy-to-understand manner, it is assumed that there is only one perforation per frame of film. In other words, if the aperture size is "36mm", 1
The pitch of the pieces is 38mm. Therefore, perforet
The pitch L between sections 2a and 2b is also 38 mm.

3 is a roller rotatably disposed on the camera body (not shown) so as to receive rotational force as the film 2 travels; 4 is a position opposing the roller 3 with the film 2 sandwiched therebetween; A pressing roller is rotatably attached to a portion 5a of a pressing lever 5, which will be described later, 5 is a pressing lever rotatably attached to a camera body (not shown) at a portion 5b, and 6 is a pressing lever with one end attached. The lever 5 is fixed to the camera body (not shown) and presses the other end.
This spring is attached to the arm 5c of the lever 5 and urges the pressing lever 5 in the counterclockwise rotation direction to press the pressing roller 4 against the roller 3.

A sprocket 7 is rotatably fitted onto the shaft 8 and has a gear portion 7b and a tooth portion 7a. Further, the sprocket 7 is sandwiched between washers 13 and 14 on both sides, and is pressed onto a protrusion 8a of the shaft 8 by a spring 12, which will be described later.

12 is a spring, and the other end is a protrusion 8 of the shaft 8.
It is locked at part b so that it does not come out, and this spring 1
The pressing force of 2 generates a frictional force between the roller 3 and the sprocket 7. Therefore, as the roller 3 rotates, the shaft 8 rotates, and the sprocket 7 rotates due to the frictional force caused by the pressing force of the spring 12. Also, the washers 13 and 14
The sprocket 7 and the protrusion 8a of the shaft 8 are rotated.
This is also to prevent the spring 12 and sprocket 7 from sticking together.

10 is a gear portion 7 of a sprocket 7 at one end.
It has a gear part 10a that meshes with the gear part 10a, and a shaft having a disk 9 at the other end, and is configured to be rotatable around the camera body (not shown). 11 is a conductive part 11a and a non-conductive part 11b
A pulse base is formed on the base plate and is fixed to the disk 9. 15 and 16 are pulse contacts that generate pulse signals as the pulse base 11 rotates; the pulse signals generated here are output to a control circuit (not shown) that controls various operations of the camera; It is processed as a signal for detecting the amount.

The film cartridge 1 used in this embodiment is the one proposed in US Pat. No. 4,834,306.

In the above structure, the film 2 is
The film is pushed out from inside the film cartridge 1 and fed by a known film feeding gear train such as No. 67534, and is then fed by known means (for example, hooking the perforations with a nail, or rolling the film with a roller). The film is wound onto the camera's film take-up spool by being pressed by a member, etc.). The process before the film 2 is wound around the camera's film take-up spool is shown in FIG.

As the film 2 is further fed from this state, it enters between the roller 3 and the pressing roller 4. Due to the frictional force generated by the biasing force of the spring 6, the roller 3 rotates to the right as the film 2 is fed. Furthermore, the sprocket 7, which is configured to rotate with the roller 3 through frictional force, also rotates in the right direction, and its teeth 7a abut against the surface of the film 2. FIG. 4 shows this state.

After this, even if the film 2 is further fed, the sprocket 7 does not rotate because the teeth 7a of the sprocket 7 are in contact with the surface of the film 2. However, roller 3
is connected to the sprocket 7 by frictional force, and the structure is such that the frictional force between the roller 3 and the film 2 is greater than this frictional force, so even if the sprocket 7 is stopped, the film As the film 2 is fed, the roller 3 is rotated by the film 2. Therefore, film 2 and low
The loss is considerably smaller than the loss due to the frictional force with La3.

As the film 2 is further fed, the part
Since the foration 2a is in a position where it can engage with the tooth 7a, the tooth 7a and the perforation 2a are connected as shown in FIG.
engages with.

[0023] After that, the perforation 2a and the tooth part 7
Since the sprocket 7 is engaged with the sprocket a, the sprocket 7 rotates as shown in FIG. 6 as the film 2 is fed.

The sprocket 7 is rotated until the perforation 2a and the tooth 7a are disengaged from each other as shown in FIG.
is positioned with the perforation 2a of the film 2 and rotates, and the roller 3 rotates due to friction with the film 2.

[0025] Here, if the diameter of the roller 3 is D, then
Since the sprocket 7 is constructed in the relationship of D×π<L, the tooth portion 7a of the sprocket 7 comes into contact with the film 2 surface before the next perforation 2b comes to a position where it can engage with the tooth portion 7a. It rotates by the frictional force of the spring 12 until it reaches the contact position. This state is shown in FIG.

Even when the film 2 is fed until the next perforation 2b is reached, the roller 3 rotates, but the sprocket 7 slips between the washer 13 and the sprocket 7 and does not rotate. This sliding position is between the washer 13 and the sprocket 7, between the washer 13 and the spring 12, or between the spring 12 and the protrusion 8b, depending on the frictional force.

[0027] Before reaching the states shown in Figs. 7 and 8, the roller 3 may slip slightly on the surface of the film 2, and the amount of feed of the film 2 and the amount of rotation of the roller 3 may not exactly match. , if the diameter D of the roller 3 is set sufficiently smaller than "L/π", the tooth 7 will be removed before the next perforation 2b comes.
A will come into contact with the second side of the film. Then, the next perforation 2b engages with the tooth portion 7a, and the sprocket 7 and the perforation 2b of the film 2 are repositioned, so that there is no rotational error of the sprocket 7.

FIGS. 9 and 10 show a second embodiment of the present invention, and parts similar to those in the first embodiment are given the same reference numerals.

The difference from the first embodiment is that the film 2
The roller 3 which rotates in contact with the film 2 is arranged not only on one side of the film 2 but also on both sides. In other words, one end has a low
A roller 16b is provided at the other end of the shaft 16 having the roller 3, and this roller 16b and the previous roller 3 are brought into contact with the film 2.

With this structure, slippage between the film 2 and the rollers 3, 16b is almost eliminated. Further, since both end surfaces abut against the film 2, twisting and tilting of the film 2 are eliminated.

According to each of the above embodiments, the roller 3 (and 16b), which is pressed against the film 2 surface and receives rotational force as the film 2 is fed due to frictional force, is connected to the sprocket 7.
are connected by the frictional force of the spring 12, and this spring 12
Since the structure is such that the frictional force between the roller 3 and the film 2 is larger than the frictional force between the roller 3 and the film 2, even if the sprocket 7 is stopped, the roller 3
is rotated by the film 2, and only the sprocket 7 slides on the film 2 at this time, so no unnecessary load is applied to the film feeding.

[0032]

[Effects of the Invention] As explained above, according to the present invention,
An elastic member is provided that connects the roller member and the sprocket and generates a friction force smaller than the friction force between the roller member and the film surface.
In the second rotation range in which the elastic member rotates without being engaged with the action, the elastic member loses the bonding force between the roller member and the sprocket, and only the roller member can rotate due to the frictional force with the film surface. I have to. Therefore, it is possible to reduce the diameter of the sprocket, thereby making the camera more compact, and at the same time, it is possible to prevent unnecessary film feeding loads from being applied.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of main parts in a first embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of main parts in the first embodiment of the present invention.

FIG. 3: The film is rolled in the first embodiment of the present invention.
FIG.

FIG. 4: The film is rolled in the first embodiment of the present invention.
FIG. 3 is a plan view showing the state immediately after entering the position of RA.

5 is a plan view showing the state at the time when the film feeding progresses from the state shown in FIG. 4 and the teeth mesh with the perforations; FIG.

6 is a plan view showing a state in which film feeding has further progressed from the state in which the tooth portions of FIG. 4 are engaged with the perforations; FIG.

7 is a plan view showing a state in which the film feed further advances from the state shown in FIG. 6 and the tooth portion comes out of the perforation; FIG.

8 is a plan view showing a state before the film feeding progresses further from the state shown in FIG. 7 and the teeth mesh with the next perforation; FIG.

FIG. 9 is a perspective view showing the configuration of main parts in a second embodiment of the present invention.

FIG. 10 is a sectional view showing the configuration of main parts in a second embodiment of the present invention.

FIG. 11 is a diagram illustrating the relationship between a conventional sprocket and film perforations.

[Explanation of sign]

2 Film 3 Roller 4 Pressing roller 7 Sprocket 7a　　　Tooth part 12 Spring 11 Pulse base 14,15 Pulse contact piece 16b Roller

Claims (1)

[Claims] Claim 1: A roller member that is pressed against the film surface and rotates by receiving a driving force as the film is fed due to frictional force; , a first rotation range in which the teeth engage and rotate with the perforations of the film;
A camera comprising: a sprocket having a second rotation range that rotates when not engaged with the sprocket; and signal generating means for generating a signal corresponding to the rotation speed of the sprocket as a film feed amount. The film feed amount detecting device is provided with an elastic member that connects the roller member and the sprocket and generates a frictional force smaller than the frictional force between the roller member and the film surface. Features: Camera film advance detection device.