JP2875848B2 - Film plane holding mechanism - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a film flat surface holding mechanism for sucking and holding a film rear surface so that a film surface becomes flat during photographing.

(Prior Art) FIGS. 8 and 9 show a film holding mechanism of a conventional camera called a tunnel system.

FIG. 8 is a sectional view including the optical axis of a conventional single-lens reflex camera,
FIG. 9 is an enlarged view showing the relationship between the film, the film aperture, and the pressure plate.

The pressure plate 74 presses against the pressure plate rail 73 on the body side, and the film
The upper end and the lower end of 75 are pressed by the film rail 72 so that the flatness of the film is ensured.

In this conventional holding mechanism, since only the upper end and the lower end of the film are regulated, the vicinity of the central portion of the film rises, and a gap of ΔL is inevitably generated.

The gap ΔL may not be negligible depending on environmental conditions such as temperature and humidity or the material of the film, and may not be negligible when photographing with a high-performance lens having a small depth of focus.

Therefore, the present inventor has already proposed an apparatus for maintaining the flatness by sucking and holding a film to solve the above problem on the pressure plate.

This film suction holding device is provided with a number of small through holes in the pressure plate, forms a variable sealed space on the back of the pressure plate, and enlarges this variable sealed space, thereby attracting the central part of the film to the pressure plate by suction and close contact. , To ensure flatness.

(Problem to be Solved by the Invention) This film suction holding device is of a type in which a spring is provided outside the variable container and a biasing force is constantly applied to the variable container in a direction of reducing the volume.

Although it is common to all the other mechanical parts of the camera including the above-mentioned device, it is desirable that the mechanism for achieving the purpose is as simple as possible and has high operation reliability.

The object of the present invention is to meet the above-mentioned demand, and is different from the proposed structure in which the variable enclosed space is constantly reduced, by applying a biasing force in the direction in which the variable enclosed space is constantly expanded, An object of the present invention is to provide a relatively simple and reliable film plane holding mechanism.

Means for Solving the Problems In order to achieve the above object, a film plane holding mechanism according to the present invention is provided on a pressure plate of a camera having a plurality of small through holes, and a film disposed on a back surface of the pressure plate, and a film on the pressure plate. A variable container that forms a variable sealed space through the through hole between the rear surface and a spring that is inserted between the pressure plate and the variable container and that applies a biasing force in a direction to always expand the variable container; A regulating member that regulates the urging force of the spring in the direction of expanding the variable container; a charging mechanism that accumulates the urging force of the spring by pressing the regulating member; and a release that releases the urging operation of the charging mechanism. Mechanism and
At the time other than photographing, the spring is charged to minimize the variable sealed space of the variable container, and at the time of photographing, the accumulation operation is released, the variable space is enlarged by the urging force of the spring, and the film is pressed against the film. It is constituted so that it may be adsorbed.

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

FIG. 1 is a cross-sectional view showing an embodiment of a variable container portion of the film plane holding mechanism according to the present invention.

The configuration of the variable container portion is used in common for three embodiments described later.

The pressure plate 4 attached to the back cover of the camera (not shown) includes rails 3 above and below the surface on which the film aperture is provided.
Pressed to 3.

The upper and lower ends of the film 5 are regulated by rails 2 and 2 and a pressure plate 4 provided inside the rails 3 and 3.

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

The outer peripheral portion of the suction rubber 6, which forms a sealed variable space through the through hole 4a with the back surface of the film, is fixed to the back side of the pressure plate via a suction rubber mounting member 9.

The central portion of the suction rubber 6 has a hole, through which the shaft portion 8b of the vacuum shaft 8 as a regulating member is inserted.

The vacuum shaft 8 includes a circular portion 8a and a shaft portion 8b protruding from the circular portion 8b.

The back surface of the circular portion 8a is adhered to the suction rubber 6. A spring 7 is inserted between the circular portion 8 a of the vacuum shaft 8 and the pressure plate 4.

The spring 7 always exerts an urging force in a direction of expanding the space of the variable container including the suction rubber 6, the vacuum shaft 8, and the like. Therefore, the urging force is accumulated in the spring 7 by pressing the vacuum shaft 8 to the left in the drawing, and the volume of the variable container is minimized.

FIG. 1 (a) shows a state where the volume of the variable container is minimum before suctioning the film.

By releasing the lock of the vacuum shaft 8 (locking members are shown in each of the three embodiments), the volume of the variable container is enlarged by the urging force of the spring 7, and a state of film suction is formed.

FIG. 1 (b) shows a state where the volume of the variable container is enlarged.

FIG. 2 is a perspective view showing a first embodiment of the film plane holding mechanism according to the present invention.

This is an example in which the rotational driving force of a motor is used as an energy storage drive source and an energy release force of the charging mechanism.

The charging mechanism and the release mechanism are a cam 10 for regulating the end of the vacuum shaft 8, a gear 16 fixed to the cam 10 by a shaft 15, a motor 14, and gears 17 and 18 for changing the rotational speed of the motor 14 and transmitting the rotation to the gear 16. And 19, a shielding plate 11 fixed to the shaft 15, and a photocoupler including a light emitting diode 13 and a phototransistor 12 are integrally formed.

The shielding plate 11 is provided with a notch groove 11a for detecting the accumulation stop position of the spring 7 and a notch groove 11b for detecting the suction start position.

FIG. 3 is a view for explaining the suction holding operation of the first embodiment, and is a view showing the relationship between the rotational position of the cam 10 and the volume of the variable container closed space.

The state of FIG. 2 showing the completion of the spring energy accumulation is the time of FIG.
This is when t ₁ is reached, and the maximum center-to-outer circumference distance L _{1 of the} cam 10 is
Engaged end of the vacuum shaft 8, the volume of the closed space is set to the minimum V ₂ to the outer peripheral position at which the.

Once in prestressed completion state at the time t _1, the motor drive signal is input according to start shooting, the motor 14 is rotated, the rotational force via the gears 19, 18, 17 and 16 further shaft 15 cam It is transmitted to 10. The cam 10 is rotated clockwise, and the end of the vacuum shaft 8 falls to the outer peripheral portion of the cam 10 at the minimum center outer peripheral distance L ₂ by the urging force of the spring 7.

The notch groove 11 of the shielding plate 11 is located at the optical axis position of the photocoupler.
If b is reached, the light emitting diode 13 is incident on the phototransistor 12, the signal is input to the motor control circuit (not shown), the driving of the motor 14 is stopped (time t _2).

From time t ₁ to t ₂ is a film suction actuation period. Although the enclosed space has not become the maximum of the volume V ₁ was at time t _2, gradually approaches the maximum volume V ₁ by the restoring force of the suction rubber 6 in the after suction hold period.

When the photographing is completed, the motor 14 rotates again, the cam 10 further rotates clockwise, and the accumulating operation of the spring 7 starts. The end of the vacuum shaft 8 climbs the outer peripheral slope of the cam, and the spring 7 is compressed. The notch groove 11a of the shielding plate 11 linked to the cam 10 reaches the optical axis of the photocoupler, and the phototransistor 1
At the time when light is incident on 2, the motor 14 is stopped, and the accumulating operation ends.

Variable container returns to the minimum volume V ₂ With this prestressing operation, this state is maintained until the start of the next shot.

 FIG. 4 is a perspective view showing a second embodiment of the present invention.

This is an example in which the rotational force of the motor is used as the energy storage drive source of the charging mechanism, and the attraction force of the electromagnet is used as the force for releasing the energy storage.

The charging mechanism is mounted on a base 30 and a bearing 31 for slidably holding the vacuum shaft 8. The charging mechanism is rotatably mounted on the base 30 via a pin.
The rotation lever 32, which is locked by c, the spring 43, which locks on the pin 44 and applies a rotating force to the rotation lever 32 in a counterclockwise direction, the base 30.
A pin 42 for limiting the counterclockwise rotation of the rotary lever 32, a motor 37, gears 35 and 36 for shifting and transmitting the torque of the motor 37, and a tip 32b of the rotary lever 32 fixed to the gear 35 The charge cam 34 that rotates the rotation lever 32 clockwise by rotating the rotation lever 32 clockwise by engaging the outer circumference with
In addition, a switch 33 is turned on around the outer periphery of the charge cam 34 to stop the motor at a predetermined position where the volume of the variable container becomes minimum.

The release mechanism is a locking claw 40 rotatably attached to the pin 39 implanted in the base 30, a spring 41 for applying a biasing force to the locking claw 40 in a counterclockwise direction, and a suction end of the locking claw 40. And an electromagnet 38.

FIG. 5 is a diagram for explaining the suction holding operation of the second embodiment, and is a diagram showing the relationship between the driving state of the electromagnet, the rotational position of the rotary lever, and the volume of the closed space. 4 shows the energy-storing completion of the spring is when it becomes a time t ₀ shown in FIG. 5,
End of the vacuum shaft 8 in a position of maximum thickness L ₂ of the rotating lever 32 is locked, the volume of the closed space is at the minimum V _2.
After completing prestressed in the time t _0, when the electromagnetic drive signal in accordance with imaging start is input, the electromagnet 38 attracts the attraction member is attached to the distal end of the locking claw 40 is rotated in a clockwise direction. Therefore, the end 32a of the rotating lever 32 locked by the locking portion 40a of the locking claw 40 is released, and the rotating lever 32 starts rotating counterclockwise by the urging force of the spring 43. Along with this, the end of the vacuum shaft 8 is
Slides down the slope 32c, reaches the minimum thickness L ₁ a position, counterclockwise rotation of the rotating lever 32 is prevented by the pin 42 (FIG. 5 time t _1).

The time t ₁ in the closed space is not turned up to the volume V _1, it approaches the maximum volume gradually by the restoring force of the suction in the rubber 6 (t ₂ from FIG. 5 t ₁₎ suction holding period after this.

When the photographing is completed (t _{2 in} FIG. 5), the motor 37 starts rotating and transmits a counterclockwise rotational force to the charge cam 34 via the gears 36 and 35. When the rotation of the rotation lever 32 is restricted by the pin 42, the end 32b of the rotation lever 32
Is in contact with the outer periphery at the position where the distance between the center and outer periphery of the charge cam 34 is minimum.

Therefore, the end 32 of the rotary lever 32 is gradually rotated clockwise by the counterclockwise rotation of the charge cam 34, and the end 32 a of the rotary lever 32 moves up the slope 40 b of the locking claw 40 and the vacuum shaft 8. End of the slope 32 of the rotary lever 32
Go up c again.

Immediately before the end 32b of the rotary lever 32 reaches the position where the distance between the center and the outer circumference of the charge cam 34 is maximized, and immediately before the distance between the center and the outer circumference falls to the minimum position, the end 32a of the rotary lever 32 is engaged with the locking claw 40. Locks to the stop 40a. Therefore, even if the end 32b of the rotary lever 32 is displaced from the outer periphery of the charge cam 34, the spring 43 prevents the counterclockwise rotation.

When the end portion 32a of the rotary lever 32 is locked to the locking portion 40a, the end of the vacuum shaft 8 is
It reaches the slope of maximum thickness L ₂ position of the.

Thus prestressing operation ends from t ₂ to t _3, the variable container is returned to minimum volume V ₂ With this prestressing operation, this state is maintained until the start of the next shot.

 FIG. 6 is a perspective view showing a third embodiment of the present invention.

This is an example in which an electromagnetic force is used as an energy storage drive source and an energy release power of the charging mechanism.

The charging mechanism and the release mechanism are provided with a locking lever 53 to which a biasing force is applied clockwise by a spring 56, mounted on the same shaft as the locking lever 53, and provided with a biasing force in a counterclockwise direction by a spring 55 in a counterclockwise direction. Yoke plates 50 and 5 which are integrally fixed by a locking auxiliary lever 54 and a collar 52 whose rotation is limited to a pin 53a implanted in the locking lever 53
1, a screw shaft having a screw groove 62b at the periphery thereof, the rotation of which is restricted by the guide 63a of the bearing 63 and the axial end of which can be moved by the guide 63a of the bearing 63, the other end being supported by the bearing 63 of the yoke plate 51, respectively. The spring 64 is rotatably mounted on the screw shaft 62 by meshing with the screw groove 62b.
The drive 61, which is urged in the counterclockwise direction and is restricted from rotating in the counterclockwise direction by the rotation stop pin 60 implanted in the yoke 50, the flat movable coil 58 fixed to the drive 61 and the yoke 50 Fixed flat magnet
It is composed of 59.

The release pin 57 implanted at the end of the driver 61 is a driver
When the 61 rotates clockwise, it comes into contact with the tip of the locking auxiliary lever 54, and when the flat movable coil 58 is supplied with power from a drive circuit (not shown), the electromagnetic force generated between the flat movable coil 58 and the flat magnet 59 causes the clock to move. A rotational force is given in the direction.

A circumferential groove 8a is provided at the tip of the vacuum shaft 8 for fitting with the tip of the locking lever 53.

FIG. 7 is a diagram for explaining the operation of the third embodiment.
FIGS. 7A to 7E are partial views showing the engagement relationship between the locking lever and the vacuum shaft and the contact relationship between the screw shaft and the vacuum shaft, respectively.

FIG. 7A shows a state in which the tip of the locking lever 53 is a vacuum shaft 8.
The variable container constituted by the suction rubber 6 and the like has a minimum volume, and the spring 7 is in an energized state. FIG. 6 shows this state.

When imaging is started and a small current with a short pulse width is applied to the flat movable coil 58 from the drive circuit, the driver 61
Rotate clockwise against 64. The rotation amount is an angle slightly larger than α ゜ since the applied current is a small current. When the driver 61 rotates clockwise, the release pin 57 pushes up the tip of the locking auxiliary lever 54 in a counterclockwise direction, and the side edge of the locking auxiliary lever 54 pushes up the pin 53a. The power is transmitted to the locking lever 53, and the tip of the locking lever 53 is disengaged from the circumferential groove 8a of the vacuum shaft 8. Therefore, the spring 7 pushes up the circular portion 8a of the vacuum shaft 8 by the accumulating force, and enlarges the variable container made of the suction rubber 6 or the like.

 Thereby, the film 5 is sucked by the pressure plate 4.

The distal end of the vacuum shaft 8 moves to a position where it abuts on the distal end of the screw shaft 62.

FIG. 7B shows a state when the above operation is performed.

When the application of the small current ends, the electromagnetic force disappears, so that the driver 61 rotates counterclockwise by the urging force of the spring 64, and the rotation is stopped by the rotation stop pin 60. As a result, the locking lever 53 whose tip has moved to a position away from the outer periphery of the vacuum shaft 8 is rotated clockwise by the urging force of the spring 56 and comes into contact with the outer peripheral surface of the vacuum shaft 8.

FIG. 7 (c) shows the state at that time, in which the film is held by suction.

Next, the photographing is completed, and a current larger than the current required for release is applied to the flat movable coil 58, so that a large electromagnetic force is generated, and the driver 61 swings clockwise at a large angle θ. As a result, the distal end of the release pin 57 lifts the distal end of the locking auxiliary lever 54, and the distal end of the locking auxiliary lever 54 escapes, so that the distal end of the releasing pin 57 moves to a position beyond the distal end of the locking auxiliary lever 54. Accordingly, the screw shaft 62 is pushed out in the direction of the variable container by the rotation of the driver 61.

The rotation of the screw shaft 62 is prevented by the guide 63a, and the movement of the driver 61 toward the variable container is prevented by the yoke plate 50.
, And the teeth of the driver 61 slide in the screw groove, so that the screw shaft 62 pushes the vacuum shaft 8 against the spring 7.

The reason why the screw shaft 62 hardly moves in the axial direction at the time of release is that the rotation angle α is small.

The leading end of the locking lever 53 moves away from the outer peripheral surface of the vacuum shaft 8 in conjunction with the raising of the locking assist lever 54, and the release pin 57 passes through the leading end of the locking assist lever 54, whereby the locking lever 53 is moved. The force pushing up in the counterclockwise direction disappears. Therefore, the tip of the locking lever 53 hits the outer peripheral surface of the vacuum shaft 8 again, and when the circumferential groove 8a of the vacuum shaft 8 is pushed to the position of the locking lever 53, the tip of the locking lever 53 becomes circular. It is fitted in the circumferential groove 8a again.

 FIG. 7D shows this state.

When the application of the current is completed, the electromagnetic force disappears, so that the driver 61 is rotated counterclockwise by the spring 64 and returns to the original position.

As a result, the screw shaft 62 retreats, but since the vacuum shaft 8 is locked by the locking auxiliary lever 54, the vacuum shaft 8 returns to the original position apart from the vacuum shaft 8.

The release pin 57 also rotates counterclockwise and again contacts the tip of the locking auxiliary lever 54, but since the locking auxiliary lever 54 escapes clockwise, the release pin 57 moves beyond the distal end of the locking auxiliary lever 54 and returns to its original position. To the position. The locking auxiliary lever 54 which has escaped clockwise returns to the original position by the spring 55.

 FIG. 7 (e) shows this state.

7 (c) to (e) are the accumulating operations for the spring 7.

(Effects of the Invention) As described above, according to the present invention, a spring is inserted between a variable container and a pressure plate to constantly apply a biasing force to the variable container in a direction of increasing the volume, and the charging member controls the regulating member. , And the releasing means cancels the storing operation of the spring. Therefore, the mechanism is relatively simple, and a highly reliable film plane holding mechanism can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a variable container portion of a film plane holding mechanism according to the present invention, and FIG. 2, FIG. 4, and FIG.
FIG. 1 is a perspective view showing first, second and third embodiments of the film plane holding mechanism according to the present invention, and FIGS. 3, 5 and 7 are views of the first, second and third embodiments. FIG. 8 is a sectional view including the optical axis of a conventional single-lens reflex camera, and FIG. 9 is an enlarged view showing a relationship among a film, a film aperture, and a pressure plate. 2 ... Film rail 3 ... Pressing plate rail 4 ... Pressing plate 5 ... Film 6 ... Suction rubber 7 ... Spring 8 ... Vacuum shaft 10 ... Cam 11 ... Shielding plate 12 ... Phototransistor 13 ... Light emission Diode 14,37 Motor 15 Shaft 16,17,18,19,35,36 Gear 30 Base 31 Bearing 32 Rotating lever 33 Switch 34 Charge cam 38 Electromagnet 39, 42, 44 Pin 40 Locking claw 41, 43, 55, 56, 64 Spring 50, 51 Yoke plate 52 Collar 53 Locking lever 54 Locking aid Lever 57: Release pin 58: Flat movable coil 59: Flat magnet 60: Rotation stop pin 61: Driver 62: Screw shaft 63: Bearing

Claims (1)

(57) [Claims] 1. A pressure plate of a camera having a plurality of small through-holes, a variable container disposed on the back surface of the pressure plate, and forming a variable sealed space through the through-hole between the back surface of the film on the pressure plate, A spring that is inserted between the pressure plate and the variable container and applies a biasing force in a direction to always expand the variable container; and a regulating member that regulates a biasing force of the spring in a direction to expand the variable container. A charging mechanism that accumulates the urging force of the spring by pressing the regulating member; and a release mechanism that cancels the urging operation of the charging mechanism. A film plane holding device configured to minimize the variable sealed space of the variable container, release the accumulation operation at the time of photographing, expand the variable space by the urging force of the spring, and attract the film to the pressure plate. Structure.