JP2000098447A - Shutter for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of a shape memory alloy incorporated in a shutter for a camera as a motive power source. SOLUTION: This shutter for the camera is assembled by using a bottom plate 12 having an aperture, and a light shielding blade is arranged so that it can be actuated on the aperture 12 on the back surface side of the bottom plate. A set member 4 opening/closing the aperture 12 by actuating the light shielding blade and the shape memory alloy 5 engaged with the member 4 and giving motive power necessary to actuate the light shielding blade are assembled on the front surface side thereof. The end of the memory 5 is engaged to freely displace with respect to the member 4 by using a terminal metal fitting 6. Thus, stress exerted on the end of the alloy 5 with the displacement of the member 4 is softened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a camera shutter. More specifically, the present invention relates to a camera shutter structure using a shape memory alloy as a power source.

[0002]

2. Description of the Related Art As an example of a conventional camera shutter,
FIG. 6 shows a focal plane shutter. A rectangular opening 12 (shown by a two-dot chain line) is provided in the center of the main plate 1. In the set state (start position), the four front blades 10 overlap each other to cover the opening 12 on the focal plane. Although not shown, a rear blade group is arranged below the front blade group so as to overlap. Unnecessary movement of the tip of each light-shielding blade is regulated by the blade holder 14. An arm 15 is pivotally supported at the left end of the main plate 1 so as to be rotatable about a shaft 16. Each leading blade 10 is locked at its rear end to an arm 15 through a hole 19. The rear blade group is also locked by an arm (not shown). The arm 15 is provided with an operation hole 17. Correspondingly, the base plate 1 is provided with a guide groove 18 along the movement locus of the operation hole 17 accompanying the rotation of the arm 15. Although not shown, a guide groove 18 is provided in the operation hole 17.
A drive pin that penetrates the base plate 1 from the back surface to the front surface via the base plate 1 is engaged. When a shutter release button (not shown) is pressed, the drive pin moves upward by a biasing force applied along a guide groove 18 provided in the main plate 1. Accordingly, the arm 15 engaged with the drive pin in the operation hole 17 rotates upward about the shaft 16. By this rotation, the leading blade 10 runs vertically upward from the illustrated start position toward the stop position to open the opening 12. Next, a rear blade group (not shown) travels in a vertical direction from the start position to the stop position, and covers the opening 12 to complete the exposure.

FIG. 7 is a schematic diagram showing a driving mechanism of a focal plane shutter, in a state before setting (pause state).
Is represented. As shown, a pair of drive members 20a and 20b and a set member 4 are assembled on the main plate 1 having the openings 12 formed therein. One driving member 20a is attached so as to be rotatable about a shaft 16a implanted in the main plate 1. The driving member 20a is provided with an iron core 21a and a driving pin 22a. The drive pin 22a penetrates the guide groove 18a provided in the main plate 1 and protrudes to the rear surface side to operate one of the front blade group and the rear blade group. The base plate 1 has an electromagnet 2 corresponding to an iron core 21a provided on a driving member 20a.
3a is provided. The other driving member 20b has the same configuration, and operates the other of the front blade group and the rear blade group. The set member 4 disposed between the drive members 20a and 20b is rotatable about a shaft 4p implanted on the main plate 1.

FIG. 8 is a partial plan view schematically showing a set state of a driving mechanism of a focal plane shutter. When the set member 4 shifts from the rest state shown in FIG. 7 to the set state shown in FIG.
a, and the drive pin 22a is
Is moved from one end to the other end, and one of the front blade group and the rear blade group is set to the start position. In this state, the iron core 21a attached to the driving member 20a is attracted to the electromagnet 23a. Similarly, the other driving member 20b is displaced, and the other of the front blade group and the rear blade group is set to the start position. Thereafter, the set member 4 returns to the rest state while leaving the pair of drive members 20a, 20b attracted by the electromagnets 23a, 23b at the set position. Next, when a shutter release button (not shown) is pressed, the electromagnets 23a, 23
3b is released, and the pair of driving members 20a, 20
b rotates sequentially according to the biasing force given in advance. Thereby, the front blade group and the rear blade group sequentially shift from the start position to the stop position, and the exposure operation is performed.

[0005]

Recently, there has been an increasing demand for downsizing and motorization of cameras, and various proposals have been made and implemented to respond to the demands. Regarding the motorization, a film winding operation is automatically performed by a motor, and a lens is also driven by a motor to automatically perform focus adjustment. or,
The use of motorized shutters has been advanced, and not only the set operation but also the release operation has been performed electrically. By motorizing the release operation, the shutter can be released immediately after the automatic focus adjustment is performed, and advantages such as less missed shutter chances can be obtained. Further, by making the setting operation electric, there is an advantage that the setting operation does not have to be performed manually.

On the other hand, there is an extremely strong demand for miniaturization,
In particular, the emergence of advanced photo system films has further accelerated. However, when the shutter is electrified, the size of the camera is inevitably increased, which goes against the demand for downsizing. For example, it is common to use an electromagnet or plunger for the release operation of a focal plane shutter, but these parts are quite large as camera parts even if they are small, and they have a three-dimensional shape. From that
It is difficult to mount compactly with other parts.
When the shutter is set electrically, it is common that the shutter is driven in association with the film winding by driving a motor. In this case, even though the motor can be shared, an interlocking mechanism such as a gear is required, which greatly restricts the layout in the camera.

[0007] In order to achieve both motorization and miniaturization of the camera,
Japanese Patent Application Laid-Open No. H10-104605 discloses a technique for setting a focal plane shutter using a shape memory alloy as a power source.
No. 78601, JP-A-10-96976, JP-A-10-115848, JP-A-10-1235
No. 83, JP-A-10-123585 and the like.

For example, the setting operation of the focal plane shutter is performed using a thin wire shape memory alloy as a power source. This makes it possible to make the mounting structure of the camera compact to some extent. One end of the shape memory alloy thin wire is locked to the set member, and the other end is locked to the main plate. The shape memory alloy generates heat when energized and self-shrinks, causing the set member to rotate from the rest position to the set position. After that, it returns from the set state to the rest state through a cooling process. However, since the end of the thin line of the shape memory alloy is fixed to the set member, a stress is applied to the end of the shape memory alloy every time the set member reciprocates between the rest position and the set position. The end of the shape memory alloy is liable to be broken due to metal fatigue, shortening the service life and reducing the reliability. There was a problem that the camera would malfunction due to sudden disconnection.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems of the prior art, the following measures have been taken. That is, the camera shutter according to the present invention has, as a basic configuration, a base plate having an opening, a light-shielding blade operably disposed on the opening, and opening and closing of the opening by operating the light-shielding blade. And a power means disposed on the base plate and engaging with the mechanism means to provide power required for operating the light shielding blade.
As a characteristic feature, the power unit includes a shape memory alloy that is deformed in response to energization, and a universal terminal that displaceably engages an end of the shape memory alloy with the mechanism unit. The stress applied to the end of the shape memory alloy due to the displacement is reduced. Specifically, the universal terminal includes a shaft fixed to the mechanism, and a metal fitting for attaching an end of the shape memory alloy to the shaft so as to be freely rotatable around the shaft. The shape memory alloy has a thin wire shape, one end of which is engaged with the mechanism means, and the other end of which is locked to the base plate. In one embodiment, the light-shielding blade includes a plurality of light-shielding blades that travel from a start position to a stop position over an opening constituting a focal plane. In this case, the mechanism includes a set member for setting the light shielding blade from the stop position to the start position, and the shape memory alloy is engaged with the set member.

The camera shutter according to the present invention uses a shape memory alloy that can be miniaturized as a power source. The end of the shape memory alloy is attached to a shutter operating mechanism (mechanical means) via a universal terminal. With this configuration, it is possible to reduce the stress applied to the end of the shape memory alloy due to the displacement of the operation mechanism, which leads to an improvement in the reliability of the camera shutter.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic plan view and a side view showing a first embodiment of a camera shutter according to the present invention. The first embodiment is an example in which the present invention is applied to a focal plane shutter. As shown, the focal plane shutter is assembled using a base plate 1 having an opening 12. Although not shown, a plurality of light shielding blades are arranged on the back surface of the base plate 1 so as to be able to operate on the opening 12. These light-shielding blades are divided into a front blade group and a rear blade group. The light-blocking blades travel from the start position to the stop position over the opening 12 forming the focal plane, and perform the exposure operation of the camera. On the surface of the base plate 1, a mechanism for operating the above-described light-shielding blade to open and close the opening 12 is assembled. Specifically, the set member 4 is attached so as to be rotatable about a shaft 4p implanted in the main plate 1. Although not shown, a driving member is assembled to the main plate 1 so as to be rotatable about a shaft 16a. A drive pin is attached to the drive member, and penetrates a guide groove 18a formed in the main plate 1 from the front surface to the back surface, and is engaged with one of the front blade group and the rear blade group. Further, although not shown, an iron core is attached to the driving member side, and an electromagnet is attached to the main plate 1 side. Further, another driving member (not shown) is attached to the main plate 1 so as to be rotatable about the shaft 16b. A drive pin is also formed on this drive member, penetrates from the front surface to the back surface through a guide groove 18b opened in the main plate 1, and is engaged with the other of the front blade group and the rear blade group.
The configuration and operation of the above-described mechanism are basically the same as those of the focal plane shutter shown in FIGS.

Power means is further compactly incorporated on the surface of the base plate 1, and engages with the above-described mechanism means.
It provides the power required to operate the shading vanes. In the present invention, the power means is a shape memory alloy 5 which is deformed in response to energization.
And a free terminal whose end is displaceably engaged with the mechanism. The stress applied to the end of the shape memory alloy 5 due to the displacement of the mechanism is reduced. In particular,
The universal terminal comprises a shaft 7 fixed to a set member 4 constituting a mechanism, and a shape memory alloy 5 rotatably displaceable around the shaft 7.
And a metal fitting 6 for attaching the end of the metal. In the present embodiment, the shape memory alloy 5 has a fine wire shape, one end of which is engaged with the set member 4 via the metal fitting 6, and the other end is locked to the main plate 1 via the metal fitting 3. . In this embodiment, the thin linear shape memory alloy 5 is stretched to the right side through the upper side from the left side of the base plate 1 using a pair of rollers 8. The tensioner 2 and the stopper 9 are arranged between the pair of rollers 8. The tensioner 2 prevents the shape memory alloy 5 from loosening and falling off the roller 8 or the like.
When a current is applied between the pair of terminal fittings 3 and 6, the thin line-shaped shape memory alloy 5 contracts and deforms, and the set member 4 rotates counterclockwise from the rest position (shown by a solid line) to a set position (two points). (Indicated by a dashed line). At this time, since the end of the shape memory alloy 5 is attached to the set member 4 via the universal terminal, the stress accompanying the rotation of the set member 4 is reduced, and the fatigue and disconnection of the shape memory alloy 5 are prevented. be able to. By using the universal terminal, the end of the shape memory alloy 5 can always be easily directed to the fulcrum of the roller 8 regardless of the position of the set member 4.

FIG. 5 is a schematic sectional view showing a specific configuration of the universal terminal. As shown, the universal terminal has a stepped screw structure. The universal terminal includes a shaft (step screw) 7 fixed to the set member 4 and a metal fitting 6 attached around the shaft so as to be freely rotatable. An end of the shape memory alloy is caulked to the metal fitting 6.

The operation of the focal plane shutter shown in FIG. 1 will be described with reference to FIG. (A) shows a rest state before setting. The shape memory alloy 5 is not energized and is loose. The tensioner 2 works to absorb the slack of the shape memory alloy generated in the relaxed state.
In the rest state, the setting member 4 is at the rest position, and the terminal fitting 6 faces the roller 8. (B) shows a set state. When the shape memory alloy 5 is energized, it shrinks and deforms,
The setting member 4 rotates counterclockwise about the shaft 4p. Even in this state, the terminal fitting 6 faces the fulcrum of the roller 8. When the setting member 4 shifts from the rest position to the setting position, the light shielding blade (not shown) is set to the start position. Thereafter, as shown in (C), the energization of the shape memory alloy 5 ends, and the shape memory alloy 5 relaxes. Accordingly, the setting member 4 rotates clockwise about the shaft 4p, and returns to the rest state. In order to facilitate the return from the set state to the rest state, a biasing force by a normal spring is applied to the set member 4. At this time, as described with reference to FIGS. 7 and 8, the light shielding blade is kept at the start position by the holding force of the electromagnet. Next, when the release button is pressed, the energization of the electromagnet is stopped, and the leading blade group and the trailing blade group sequentially travel from the start position to the stop position to perform the exposure operation.

FIG. 3 is a schematic view showing a second embodiment of the camera shutter according to the present invention. In the present embodiment, the opening and closing of the opening 51 is performed using one light-shielding blade 50. (A) shows a shielding state, and an opening 51 is a light shielding blade 50.
Covered with. The light-shielding blade 50 is rotatable about a shaft 50p, is urged in a counterclockwise direction by a spring 53, and is in contact with the contact 52. An operation piece 54d of a drive lever is engaged with the end 50t of the light shielding blade 50. The operation piece 54d has a predetermined elasticity. (B) shows an open state. When the operating piece 54d of the drive lever moves from left to right in the drawing by operating a release lever (not shown), the light-shielding blade 50
, The opening 51 is opened. Subsequently, as shown in FIG.
When 4d moves away from the end 50t, the light shielding blade 50
With the urging force of No. 3, it returns in the counterclockwise direction, contacts the stud 52, and shields the opening 51. The above operation completes one exposure.

FIG. 4 is a schematic diagram showing the entire structure of the camera shutter shown in FIG. This camera shutter includes a drive lever 54 and a charge lever 5 in addition to the light shielding blade 50.
5, a thin line shape memory alloy 57 and a release lever 58 are provided. As described above, the operating piece 5 of the drive lever 54
4d is engaged with the end 50t of the light shielding blade 50. When the release lever 58 is operated in this state, the drive lever 5
The operation piece 54d of No. 4 shifts from left to right in the drawing, and one exposure operation is performed as shown in FIGS. In order to prepare for the next exposure operation, it is necessary to return the operation piece 54d of the drive lever 54 from the position shown in FIG. 3C to the position shown in FIG. Charge lever 5 for this
5 is used. A spring 56 is attached to one end of the charge lever 55, and a thin wire-shaped shape memory alloy 57 is attached to the other end via a universal terminal 60. When the shape memory alloy 57 is energized, the charge lever 55
Rotate around the center 9 and push the drive lever 54 to return to the initial position. At this time, the release lever 58 is
4 and the next release operation becomes possible. Since the shape memory alloy 57 is attached to the charge lever 55 via the universal terminal 60, it is possible to reduce the stress accompanying the rotational displacement of the charge lever 55.

[0017]

As described above, according to the present invention,
In a camera shutter, a shape memory alloy used as a power source is attached to an operation mechanism of a light-shielding blade via a universal terminal, thereby relieving stress applied to an end of the shape memory alloy due to displacement of the operation mechanism. . With such a configuration, it is possible to provide a highly reliable and highly reliable camera shutter.

[Brief description of the drawings]

FIG. 1 is a schematic plan view and a side view showing a first embodiment of a camera shutter according to the present invention.

FIG. 2 is a schematic diagram for explaining the operation of the first embodiment.

FIG. 3 is an operation explanatory diagram of a second embodiment of the camera shutter according to the present invention.

FIG. 4 is a schematic diagram illustrating an overall configuration of a second embodiment.

FIG. 5 is a schematic partial sectional view showing a configuration of a universal terminal used for a camera shutter according to the present invention.

FIG. 6 is a plan view showing an example of a conventional focal plane shutter.

FIG. 7 is a schematic view showing a conventional focal plane shutter.

FIG. 8 is a schematic view showing a conventional focal plane shutter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ground plate, 2 ... Tensioner, 3 ... Metal fittings, 4
... Set member, 5 ... Shape memory alloy, 6 ... Hardware, 7 ... Shaft, 8 ... Roller, 12 ... Opening

Claims (4)

[Claims] 1. A base plate having an opening, a light-shielding blade operably disposed on the opening, a mechanism for operating the light-shielding blade to open and close the opening, and a mechanism disposed on the base plate. A camera means provided with power means for engaging the means to apply power required for operating the light-shielding blade, wherein the power means comprises: a shape memory alloy which is deformed in response to an electric current; and an end of the shape memory alloy. A shutter for a camera, comprising: a free terminal that displaceably engages a portion with the mechanism means, wherein a stress applied to an end of the shape memory alloy with the displacement of the mechanism means is reduced. 2. The apparatus according to claim 1, wherein the universal terminal comprises a shaft fixed to the mechanism, and a metal fitting for attaching an end of the shape memory alloy to the shaft so as to be rotatable and displaceable around the shaft. 2. The camera shutter according to 1. 3. The shape memory alloy according to claim 1, wherein the shape memory alloy has a fine wire shape, one end of which is engaged with the mechanism means, and the other end of which is locked to the main plate. Camera shutter. 4. The light-shielding blade comprises a plurality of light-shielding blades traveling from a start position to a stop position over an opening constituting a focal plane, and the mechanism sets the light-shielding blade from the stop position to the start position. 2. The camera shutter according to claim 1, further comprising a set member, wherein the shape memory alloy is engaged with the set member.