JPH0359631A - Attracting mechanism for film plane holding device - Google Patents

Abstract

PURPOSE:To reduce the current consumption by supplying a one-shot pulse current to a fixed coil arranged outside a movable permanent magnet at the time of photography and attracting the rear surface end part of the movable permanent magnet to the rear end surface of a yoke, and expanding a sealed variable space. CONSTITUTION:One end of a suction rubber shaft 11 is fitted to the center part of the suction rubber 6 which forms the sealed variable space and moving magnets 8 and 9 are fixed to the shaft 11; and the fixed coil 7 is arranged outside them and the front end part of the magnet 8 is attracted to the front end surface of the yoke 15 with its attractive force except in photography. For fixed exposure, the one-shot pulse current is supplied to the fixed coil 7, the rear end part of the moving magnet 9 is attracted to the rear end surface of the yoke 15 to expand the sealed variable space, and when the current is cut off, this state is maintained with the attractive force of the magnet 9. When the exposure is completed, a one-shot pulse current having the opposite polarity is supplied to the fixed coil 7 to return the moving magnets 8 and 9 to their original positions. Consequently, no current need not be supplied during film attraction and the electric consumption is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suction mechanism of a film flatness holding device of a camera for maintaining the correct flatness of a film every time a photograph is taken.

(Prior Art) A mechanism called a so-called tunnel system is employed to hold the film in the aperture section of a conventional camera using a silver halide film.

However, since this mechanism only regulates the top and bottom edges of the film, the flatness may not be negligible depending on environmental conditions such as temperature and humidity, or the material of the film. Under these conditions, the flatness of the film becomes a problem.

To solve this problem, the inventor of the present invention has already proposed a film flatness holding device that can maintain flatness even in the center of the film.

FIG. 7 is a partially sectional perspective view schematically showing the film flatness holding device.

Film rails 2, 2 are placed above and below the film aperture on the surface of the camera body 1 where the film aperture is provided.
．． Pressure plate rails 3, 3 are provided on the outside thereof.

A pressure plate spring 54 is caulked to the film pressure plate 4 with a caulking stud 55, and the pressure plate 4 is attached to the back cover of a camera (not shown) via the pressure plate spring.

A plurality of through holes 4a are provided near the center of the pressure plate 4,
On the back side of the pressure plate, there is an annular fixing plate 4 surrounding the group of through holes.
1 is attached by screws 42.

A cup 40 for air suction is attached to the fixed plate 41 through a bellows 43 in an airtight manner.

Further, the pressure plate 4 has a stud 5, a screw 52. Installation is ear 53
An outer yoke 49 is fixed by the outer yoke 49, and a bearing 48 having a through hole 50 is supported at the center of the outer yoke 49.

A shaft 47 is fixed to the center of the cup 40, and the shaft 47 is loosely fitted into a through hole 50 of a bearing 48.

The spring 46 is inserted between the bearing 48 and the cup 40, so that the assembly of the cup 40 and the bellows 43 is biased toward the pressure plate 4, and the cup 40 is in contact with the fixed plate 41.

A movable coil 44 is provided on the outer periphery of the cup 40, and this portion is inserted into the gap between the ring magnet 45 and the yoke 49.

(Problems to be Solved by the Invention) In the film plane holding device described above, when photographing, current is supplied to the movable coil 44, and the ring magnet 45. York 49. A magnetic circuit is formed through gaps between the magnet 45 and the moving coil 44 and between the moving coil 44 and the yoke. Therefore, according to Fleming's left-hand rule, the movable coil 44 is attracted in a direction away from the pressure plate 4, the volume of the bellows increases, and the vicinity of the center of the film 16 is attracted to the pressure plate 4.

The above mechanism has the disadvantage that current must continue to flow through the moving coil while the film is being sucked, resulting in large current consumption.

The purpose of the present invention is to eliminate the need to continue supplying current to the coil during film suction and holding, and to reduce the amount of current dissipation to an extremely low level.
It is an object of the present invention to provide a suction mechanism for a film flatness holding device having a simple configuration.

(Means for Solving the Problems) In order to achieve the above object, the suction mechanism of the film plane holding device according to the present invention is provided with a through hole of I or more in size in the pressure plate of the camera, and a variable sealing mechanism on the back surface of the pressure plate surrounding the through hole. In a suction mechanism of a film flatness holding device that forms a space and tightly adsorbs the film onto a pressure plate by expanding the volume of the sealed variable space, the suction mechanism is movable in a direction perpendicular to the pressure plate;
a drive shaft that expands the volume of the sealed variable space when moved in a direction away from the pressure plate; a ring-shaped movable permanent magnet fixed to the drive shaft; and a fixed coil disposed outside the movable permanent magnet. and a yoke that is provided around the fixed coil and has both ends capable of being attracted to the front end and the rear end of the movable permanent magnet, respectively, and an attraction mechanism drive circuit that supplies current to the fixed coil. When not photographing, the front end of the movable permanent magnet is in contact with the front end surface of the yoke due to the attractive force of the permanent magnet, and when photographing, a one-shot pulse current is passed through the fixed coil to The rear end of the movable permanent magnet is attracted to the rear end of the yoke to expand the sealed variable space, and even when the current is cut off, this state is maintained by the attraction force of the movable permanent magnet, and after the completion of imaging, the fixed coil The movable permanent magnet is returned to its original position by passing a one-shot pulse current of opposite polarity through the magnet.

According to such a configuration, the flatness of the film can be maintained during exposure by simply supplying a one-shot pulse current from the drive circuit immediately before film exposure and a one-shot pulse current of opposite polarity immediately after film exposure, and the current Consumption can be reduced.

(Example) Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a partially sectional perspective view showing an embodiment of the suction mechanism of the film flatness holding device according to the present invention.

A pressure plate 4 mounted on the back cover of the camera (not shown) is pressed against rails 3.3 above and below the side of the camera where the film aperture is provided.

The upper and lower ends of the film 16 are regulated by the rails 2, 2 and the pressure plate 4 provided inside the rails 3.3.

A through hole 4 for film suction is provided near the center of the pressure plate 4.
A large number of a are provided.

The outer periphery of a conical suction rubber 6 is airtightly fixed to the back side of the pressure plate so as to surround the group of through holes 4a.

This suction rubber 6 is the center part (the part corresponding to the apex of the cone)
The end portion 11b of the suction rubber shaft (drive shaft) 11 is attached to this hole.

The end portion 11b of the suction rubber shaft 11 has a flange shape, and as described later, when the suction rubber shaft 11 moves to the right, the flange portion comes into contact with the inner wall of the suction rubber 6 to form a more reliable airtight state. be done.

The other end Lea of the suction rubber shaft 11 also has a large shaft diameter, and is loosely fitted into a bearing 13a provided in the center of the case 13 that houses the entire mechanism section.

A magnet mounting member 14, to which an annular moving magnet A8 and a moving magnet B9 are fixed, is loosely fitted into the center of the suction rubber shaft 11.

This magnet mounting member 14 is restricted from moving in the left direction by an E ring 19 engaged with the suction rubber shaft 11, and a spring lO is inserted between the magnet mounting member 14 and the end 11a of the suction rubber shaft 11. There is.

The magnet mounting member 14 is always pressed against the E-ring 19 by the spring 10.

As shown in FIG. 3, the polarity of the moving magnet 8 is such that the pressure plate side is the north pole and the opposite side is the south pole, and the moving magnet 9 has the polarity such that the moving magnet 8 side is the south pole and the opposite side is the north pole.

A fixed coil 7 is arranged outside the moving magnet 8.9, and a yoke 15 is attached to the case 13 so as to surround the fixed coil 7.

Ends 15a and 15b of the yoke 15 protrude inward from the fixed coil 7, with the end 15a being a part of the N pole side of the moving coil 8, and the end 15b being a part of the N pole side of the moving coil 9.
It can be adsorbed to a part of the pole via spacers 5 and 12, respectively.

FIG. 4 is a block diagram showing an embodiment of a drive circuit for operating the suction mechanism.

This suction mechanism drive circuit releases the film suction during film feeding and applies suction force only during film exposure.

When the start signal (11) of the front curtain of the shutter is input to the signal processing circuit 24, the film suction pump control circuit 20 applies a rectangular one-shot pulse P1 to the coil 7 as shown in FIG. 3(a). A signal generated when the exposure by the shutter is completed.

When the trailing curtain run completion signal (12) is input, the film adsorption pump control circuit 20
applies a one-shot pulse P2 having a polarity opposite to that of the one-shot pulse P1 to the coil 7.

FIG. 2 is a schematic diagram for explaining the magnetic circuit formed in FIG. 1.

As shown in FIG. 1(a), immediately before film exposure, the N pole of the moving magnet 8 is attracted to the end 15a of the yoke 15 due to the magnetic force of the moving magnet 8, and the film 16 is attracted to the pressure plate 4. It has not been.

When the one-shot pulse P1 is applied by the film suction pump control circuit 20, an N pole is generated at the end 15a of the coil 15, and an S pole is generated at the end 15b, and the yoke 15 → spacer 5 → magnet 8 → magnet attachment A magnetic circuit is formed along the path of member 14 -> magnet 9 -> gap -> spacer 12 - yoke 15 .

Therefore, the north pole of the magnet 8 repels the north pole generated at the end 15a, and the north pole of the magnet 9 is attracted to the south pole generated at the end 15b, causing the magnet mounting member 14 to start moving rightward. .

At this time, a force for moving the suction rubber shaft 11 is transmitted via the spring 10, so that the central portion of the suction rubber 6 is subjected to a force for gradual movement in response to the movement of the magnet attachment member 14, causing it to move to the right.

FIG. 1(b) shows a state in which the N pole of the magnet 9 is attracted to the end portion 15b of the yoke 15, and the film 16 is attracted to the pressure plate 4. In this state, the pulse P1 is not supplied to the coil 7, and the coil 7 is maintained only by the attractive force generated by the magnetic force of the magnet 9.

After the exposure is completed, the film adsorption pump control circuit 20 generates a one-shot pulse P having the opposite polarity to the one-shot pulse P1.
2 is applied, the yoke 15→spacer 12→magnet 9→magnet mounting member 14→magnet 8→
A magnetic circuit is formed along the path from gap to spacer 5 to yoke 15, and an N pole is generated at the end 15b and an S pole is generated at the end 15a, so the N pole of the magnet 9 is repelled and the N pole of the magnet 8 is attracted. Then, the magnet mounting member 14 starts moving leftward and returns to its original position.

FIG. 3 (bl shows the temporal change in the force with which the film 16 is attracted).

The reason why the rise of the suction force is gentler than that of the pulse P1 is that the force is directly transmitted to the suction rubber by the spring 10, and damage to the suction rubber is alleviated.

FIG. 5 is a sectional view showing another embodiment of the present invention.
) shows a state in which the film (not shown) is not suctioned, and (b) shows a state in which it is suctioned.

The difference from the embodiment shown in Fig. 1 is that the moving magnet is
11, and the number of yokes and coils is two.The other configurations are the same as in FIG.

One moving magnet 31 is fixed to a magnet mounting member 36 that is loosely fitted onto the suction rubber shaft 11.

Two coils 3 are placed on the outside of this moving magnet 31.
2 and 33 are arranged, and yokes 34 and 3 respectively.
It is housed in 5.

Yokes 34 and 35 are attached to case 13.

FIG. 6 is a diagram for explaining the magnetic circuit of FIG. 5.

The pressure plate side of the moving magnet 31 is magnetized to the north pole, and the opposite side is magnetized to the south pole, and when the film is not attracted, the north pole of the moving magnet 31 is attracted to the end 34a of the yoke 34.

In the case of this embodiment, the drive circuit is capable of simultaneously supplying current to the coils 32 and 33. During film exposure, the drive circuit supplies the coil 32 with an N pole at the end 34a of the yoke 34, and the coil 33 with the yoke. A one-shot pulse current having a polarity such that an N-pole is generated is applied to the end portion 35a of the electrode 35 (FIG. 6(a)).

As a result, the moving magnet 31 moves to the right, and as shown in FIG. 6(b), the moving magnet 31 moves to the right.
The pole is attracted to the end 35a of the yoke 35.

When the exposure is completed, the coil 3
A one-shot pulse current having a polarity opposite to that during film exposure is applied to 2 and 33.

As a result, the moving magnet 31 returns to its original position, and the film suction operation during film exposure is completed.

(Effects of the Invention) As explained above, the present invention has a suction mechanism that suctions film to the pressure plate of a camera, and one end of the suction rubber shaft is attached to the center of the suction rubber that forms a sealed variable space, and a moving magnet is attached to this shaft. A fixed coil is placed on the outside of the moving magnet, and when not shooting, the front end of the moving magnet is attracted to the front end of the yoke by the attraction force of the magnet, and when film is exposed, a fixed coil is placed on the outside of the moving magnet. By applying a shot pulse current, the rear end of the moving magnet is attracted to the rear end of the yoke, expanding the sealed variable space. When the current is cut off, this state is maintained by the attraction force of the moving magnet, and after the exposure is completed, the fixed coil The moving magnet is returned to its original position by passing a one-shot pulse current of opposite polarity through the magnet. Therefore, during film exposure, it is only necessary to supply a driving current at the start and end of film suction, and there is no need to supply current during film suction, resulting in the effect that electricity consumption can be reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the suction mechanism of the film flat holding device according to the present invention. Fig. 2 is a diagram for explaining the magnetic circuit formed in Fig. 1, Fig. 3(a) is a diagram showing the characteristics of the current flowing through the coil,
Fig. 3 (bl is a diagram showing the attraction force of the movable magnet. Fig. 4 is a block diagram showing an embodiment of a drive circuit for operating the attraction mechanism, and Fig. 5 is a diagram showing another embodiment of the present invention. in,
Figure (a) shows the state in which the film is not suctioned;
b) shows the state in which the film is being sucked. FIG. 6 is a diagram for explaining the magnetic circuit of FIG. 5. FIG. 7 is a partially sectional perspective view showing an example of a conventional film flatness holding device. 2.3...Rail 4...Press plate 5.12...Spacer 6...Suction rubber 7...Coil 8...Movable permanent magnet A (ring-shaped moving magnet A) 9... Movable permanent magnet B (ring-shaped moving magnet B) 10... Spring 11... Suction rubber shaft 13... Case 14. 36... Magnet mounting member 15... Yoke (7... Arrow 18 ... Magnetic circuit 20 ... Film adsorption pump control circuit 24 ... Signal processing circuit 31 ... Movable permanent magnet (ring-shaped moving magnet) 32 ... Coil A 33 ... Coil B 34 ...・Yoke A 35... Yoke B 40... Cup 41... Fixed plate 42... Screw 43... Bellows 44... Moving coil 45... Ring magnet 6... Spring 7...・Cup shaft 8...Fixed bearing 9...Outer yoke 0...Fixed bearing center hole l...Stat 2...Screw 3...Mounting with ear 4...Press plate spring 5...・Caulking studs

Claims (1)

[Claims] One or more through-holes are provided in the pressure plate of the camera, a sealed variable space is formed on the back surface of the pressure plate surrounding the through-holes, and the film is held flat by closely adsorbing the film onto the pressure plate by expanding the volume of this sealed variable space. In the suction mechanism of the device,
a drive shaft that is movable in a direction perpendicular to the pressure plate and expands the volume of the sealed variable space when moved in a direction away from the pressure plate; a ring-shaped movable permanent magnet fixed to the drive shaft; A fixed coil arranged outside the permanent magnet, a yoke provided around the fixed coil and having both ends capable of being attracted to the front end and the rear end of the movable permanent magnet, respectively, and a yoke that connects the fixed coil with an electric current. and a suction mechanism drive circuit for supplying the fixed coil. By applying a one-shot pulse current to the movable permanent magnet, the rear end of the movable permanent magnet is attracted to the rear end face of the yoke to expand the sealed variable space, and even when the current is interrupted, this state is maintained by the attractive force of the movable permanent magnet. A suction mechanism for a film flatness holding device, characterized in that the movable permanent magnet is configured to return the movable permanent magnet to its original position by passing a one-shot pulse current of opposite polarity through the fixed coil after the completion of photographing.