JP7624336B2 - Blade drive device and imaging device equipped with same - Google Patents

Description

The present invention relates to a blade drive device and an imaging device equipped with the same, and in particular to a blade drive device for driving shutter blades in an imaging device such as a camera.

In imaging devices such as cameras, the exposure aperture is opened and closed by moving the shutter blades at high speed to expose the imaging element. Conventionally, focal plane shutters, which are made up of a leading blade and a trailing blade, are known as blade drive devices that drive the shutter blades at high speed, and which move the leading blade and the trailing blade in the same direction by an actuator. In such focal plane shutters, the space formed between two base plates is often divided into a leading blade chamber and a trailing blade chamber by a partition plate, and the leading blade is often housed in the leading blade chamber and the trailing blade is often housed in the trailing blade chamber (see, for example, Patent Document 1).

If such a partition becomes deformed or damaged, it is thought that this could have a negative effect on the operation of the leading and trailing blades, so it is preferable for the partition to have as high a rigidity as possible. On the other hand, when a blade moving at high speed stops, the blade may sway in the thickness direction. For this reason, if the rigidity of the partition is made high, it is thought that the swaying blade may come into contact with the partition and be damaged.

JP 2001-281732 A

The present invention was made in consideration of the problems with the conventional technology, and aims to provide a blade drive device that can operate at high speeds while reducing the impact on the blades of the partition plate that separates the leading blade chamber from the trailing blade chamber.

According to one aspect of the present invention, there is provided a blade drive device capable of high-speed operation while reducing the influence of a partition plate separating a leading blade chamber and a trailing blade chamber on the blades. The blade drive device includes a pair of base plates having an opening, at least one leading blade movable between a first closing position that closes the opening and a first retracted position located on the blade running direction side of the opening, at least one trailing blade movable between a second retracted position located on the opposite side of the opening in the blade running direction and a second closing position that closes the opening, and a partition section that divides a space formed between the pair of base plates into a leading blade chamber that houses the leading blade and a trailing blade chamber that houses the trailing blade. The partition section includes a first partition plate that extends around a first region located on the blade running direction side of the opening, and a second partition plate that extends around a second region located on the opposite side of the opening in the blade running direction.

FIG. 1 is a front view showing a blade drive device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing a part of the blade drive device shown in FIG. FIG. 3 is a cross-sectional view taken along line AA of FIG. FIG. 4 is a front view showing a state when the blade drive device shown in FIG. 1 has completed an exposure operation. FIG. 5 is a front view showing the relationship between the partition plate and the base plate in the blade drive device shown in FIG. FIG. 6 is a schematic diagram showing the relationship between the rear blade and the partition plate when the exposure operation shown in FIG. 4 is completed.

Below, an embodiment of a blade drive device according to the present invention will be described in detail with reference to Figs. 1 to 6. In Figs. 1 to 6, identical or corresponding components are given the same reference numerals and duplicated descriptions will be omitted. In addition, in Figs. 1 to 6, the scale and dimensions of each component may be exaggerated or some components may be omitted. In the following description, unless otherwise specified, terms such as "first" and "second" are used only to distinguish components from each other and do not indicate a specific order or sequence.

Figure 1 is a front view showing a blade drive device 1 in one embodiment of the present invention. The blade drive device 1 in this embodiment is described as a focal plane shutter incorporated in an optical device such as a camera, but this is merely an example, and the blade drive device according to the present invention is not limited to use as such a shutter. Figure 1 shows the state when the setting operation by the camera is completed.

As shown in FIG. 1, the blade drive device 1 in this embodiment includes a first base plate 10 with a rectangular opening, a second base plate 12 (cover plate) with an opening of substantially the same shape as the opening of the first base plate 10, and eight blades 31 to 38 housed in the space formed between the pair of base plates 10, 12. An exposure opening S is formed by the openings of the base plates 10, 12. This blade drive device 1 is incorporated into an imaging device equipped with an imaging element (not shown) such as a CCD or CMOS sensor. The imaging element is located on the front side of the blade drive device 1 in FIG. 1, and light from a subject passes through the exposure opening S of the base plates 10, 12 and enters the imaging element.

Figure 2 is an exploded perspective view showing a part of the blade drive device 1, and Figure 3 is a cross-sectional view taken along line A-A in Figure 1. In Figure 3, in order to facilitate understanding, the thickness of some elements is exaggerated and the elements on the +Z direction side of the first base plate 10 are omitted from the illustration, resulting in a simplified overall view. As shown in Figure 2, each of the blades 31 to 38 is a thin plate-like member that extends in the X direction as a whole. In this embodiment, of the blades 31 to 38, the blades 31 to 34 that are stacked in order become the leading blades that make up the leading curtain of the focal plane shutter, and the blades 35 to 38 that are stacked in order become the trailing blades that make up the trailing curtain.

A first partition plate 51 and a second partition plate 52 are disposed between the first base plate 10 and the second base plate 12 (not shown in FIG. 2). These partition plates 51, 52 are both disposed between the leading blades 31-34 and the trailing blades 35-38, and as shown in FIG. 3, a leading blade chamber R1 that houses the leading blades 31-34 is formed between the partition plates 51, 52 and the second base plate 12, and a trailing blade chamber R2 that houses the trailing blades 35-38 is formed between the partition plates 51, 52 and the first base plate 10.

The blade drive device 1 also includes leading blade arms 41, 42 connected to the leading blades 31-34, and trailing blade arms 43, 44 connected to the trailing blades 35-38. The leading blades 31-34 are connected to the leading blade arms 41, 42, respectively, by rivets or the like, and the leading blades 31-34 and the leading blade arms 41, 42 are rotatable relative to each other. Thus, a link mechanism is formed by each of the leading blades 31-34 and the leading blade arms 41, 42. The trailing blades 35-38 are connected to the trailing blade arms 43, 44, respectively, by rivets or the like, and the trailing blades 35-38 and the trailing blade arms 43, 44 are rotatable relative to each other. Thus, a link mechanism is formed by each of the trailing blades 35-38 and the trailing blade arms 43, 44.

The leading blade arm 41 is configured to be rotatable around the rotation shaft 21, and the leading blade arm 42 is configured to be rotatable around the rotation shaft 22. As shown in FIG. 2, a leading blade drive lever 61 is disposed on the +Z direction side of the first base plate 10. This leading blade drive lever 61 is configured to be rotatable around the rotation shaft 21, and a connecting portion 45 is provided at the tip of the leading blade drive lever 61. An arc hole 11 is formed in the first base plate 10 along an arc centered on the rotation shaft 21, and the connecting portion 45 of the leading blade drive lever 61 is connected to the connecting hole 41A of the leading blade arm 41 through this arc hole 11.

The rear blade arm 43 is configured to be rotatable around the rotation shaft 23, and the rear blade arm 44 is configured to be rotatable around the rotation shaft 24. As shown in FIG. 2, a rear blade drive lever 62 is disposed on the +Z direction side of the first base plate 10. This rear blade drive lever 62 is configured to be rotatable around the rotation shaft 23, and a connecting part 46 is provided at the tip of the rear blade drive lever 62. An arc hole 13 is formed in the first base plate 10 along an arc centered on the rotation shaft 23, and the connecting part 46 of the rear blade drive lever 62 is connected to the connecting hole 43A of the rear blade arm 43 through this arc hole 13.

In this configuration, when the leading blade drive lever 61 is rotated around the rotation shaft 21 by a drive mechanism (not shown), the connecting portion 45 of the leading blade drive lever 61 moves along the arc hole 11, and the leading blade arm 41 connected to this connecting portion 45 rotates around the rotation shaft 21. When the leading blade arm 41 rotates around the rotation shaft 21, the leading blade arm 42 also rotates around the rotation shaft 22 due to the link mechanism described above, and the leading blades 31 to 34 move mainly in the Y direction on the XY plane (movement plane) while changing the overlapping areas.

Similarly, when the trailing blade drive lever 62 is rotated around the rotation shaft 23 by a drive mechanism (not shown), the connecting part 46 of the trailing blade drive lever 62 moves along the arc hole 13, and the trailing blade arm 43 connected to this connecting part 46 rotates around the rotation shaft 23. When the trailing blade arm 43 rotates around the rotation shaft 23, the above-mentioned link mechanism causes the trailing blade arm 44 to also rotate around the rotation shaft 24, and the trailing blades 35 to 38 move mainly in the Y direction on the XY plane (movement plane) while changing the area where they overlap with each other.

In the completed state of the setting operation shown in FIG. 1, the leading blades 31-34 cover the opening S, and the trailing blades 35-38 are retracted to a position on the +Y side of the opening S. When the leading blade drive lever 61 and the trailing blade drive lever 62 are driven from this state by the drive mechanism, the leading blades 31-34 and the trailing blades 35-38 move mainly in the -Y direction (blade travel direction) on the XY plane. At this time, the trailing blade 35 moves in the -Y direction while being separated from the leading blade 34 in the Y direction. Therefore, a slit for exposure is formed between the leading blade 34 and the trailing blade 35. This slit moves in the -Y direction together with the movement of the leading blades 31-34 and the trailing blades 35-38, and exposure of the imaging surface is performed. FIG. 4 shows the state when this exposure operation is completed.

At the completion of the exposure operation shown in FIG. 4, the trailing blades 35-38 are blocking the opening S, and the leading blades 31-34 are retracted to a position on the -Y side of the opening S. In this way, the leading blades 31-34 are movable between a blocking position (first blocking position (FIG. 1)) that blocks the opening S and a retracted position (first retracted position (FIG. 4)) located on the -Y side (blade travel direction) of the opening S, and the trailing blades 35-38 are movable between a retracted position (second retracted position (FIG. 1)) located on the +Y side of the opening S and a blocking position (second blocking position (FIG. 4)) that blocks the opening.

Figure 5 is a front view showing the relationship between the partition plates 51, 52 and the base plates 10, 12. As shown in Figure 5, the first partition plate 51 extends around the first region S1 located on the -Y direction (blade running direction) side of the exposure opening S, and has a base 511 extending in the X direction and arms 512 extending from both sides of the base 511 toward the +Y direction. The second partition plate 52 extends around the second region S2 located on the +Y direction side of the exposure opening S, and has a base 521 extending in the X direction and arms 522 extending from both sides of the base 521 toward the -Y direction. The arms 512 of the first partition plate 51 and the arms 522 of the second partition plate 52 are arranged to face each other in the Y direction with a small gap between them.

In general, in a focal plane shutter that drives the blades at high speed, the vibration and impact that the blades receive are greatest when the exposure operation is completed and the blades stop. Therefore, when the exposure operation is completed, the blades on the -Y direction (blade travel direction) side along which the blades 31 to 38 move will vibrate significantly. As mentioned above, if the rigidity of the partition plate located near the blade that vibrates significantly is high, the vibrating blade may come into contact with the partition plate and be damaged. On the other hand, it is preferable to increase the rigidity of the partition plate on the opposite side in the +Y direction to increase reliability.

From this perspective, in this embodiment, the partition plate separating the leading blade chamber R1 and the trailing blade chamber R2 is divided into two in the blade running direction, thereby reducing the effect of the partition plate on the blades 31 to 38 and enabling the blades 31 to 38 to operate at high speed. In other words, the material and thickness of the first partition plate 51 located in the -Y direction area and the second partition plate 52 located in the +Y direction area can be changed according to the characteristics of the blades passing nearby. For example, the first partition plate 51 located in the -Y direction area where the blades are expected to swing significantly when the exposure operation is completed can be made of resin, so that when the nearby blades swing in the thickness direction (Z direction), the partition plate 51 can bend to reduce damage to the blades, while the second partition plate 52 located in the +Y direction area can be made of a highly rigid metal.

In this way, in order to effectively respond to the swaying of the blades in the -Y direction and ensure the rigidity of the partition plate in the +Y direction, it is preferable that the first area S1 surrounded by the first partition plate 51 is smaller than half of the total area of the opening S, and that the second area S2 surrounded by the second partition plate 52 is larger than half of the total area of the opening S.

In addition, the inventor discovered in the process of developing the present invention that the second rear blade (rear blade 36) sways the most in the thickness direction when the exposure operation is completed, and found that when the dividing position G of the partition plate 51 and the partition plate 52 is set near the area W (shaded area) where the rear blade 35 (first rear blade) and the rear blade 36 (second rear blade) overlap when the exposure operation is completed, as shown in FIG. 6, a good balance is achieved between responding to the blade's swing and ensuring the rigidity of the partition plate. Therefore, it is preferable that the first partition plate 51 and the second partition plate 52 are arranged so as to face each other in the Y direction near the area W where the rear blade 35 and the rear blade 36 overlap when the rear blades 35 to 38 move to a position that blocks the opening S (second blocking position).

In addition, the terms used in this specification, such as "top," "bottom," "upper," "lower," "upper side," "lower side," "bottom," and other terms indicating positional relationships, are used in relation to the illustrated embodiment and may change depending on the relative positional relationship of the devices.

As described above, according to the first aspect of the present invention, a blade drive device capable of high-speed operation while reducing the influence of a partition plate separating a leading blade chamber and a trailing blade chamber on the blades is provided. This blade drive device includes a pair of base plates having an opening, at least one leading blade movable between a first closing position that closes the opening and a first retracted position located on the blade running direction side of the opening, at least one trailing blade movable between a second retracted position located on the opposite side of the opening in the blade running direction and a second closing position that closes the opening, and a pair of partition plates that divide the space formed between the pair of base plates into a leading blade chamber that houses the leading blade and a trailing blade chamber that houses the trailing blade. The pair of partition plates includes a first partition plate extending around a first region of the opening located on the blade travel direction side, and a second partition plate extending around a second region of the opening located on the opposite side of the blade travel direction. It is preferable that at least one of the material and thickness of the first partition plate and the second partition plate is different.

In this way, by separating the leading blade chamber that houses the leading blade from the rear blade chamber that houses the rear blade with two partition plates separated in the blade running direction, it is possible to change the material and thickness of the partition plate according to the characteristics of the blades passing nearby so as to reduce the impact on the blades. Therefore, with the blade drive device of the present invention, it is possible to operate the blades at high speed while reducing the impact on the blades of the partition plate that separates the leading blade chamber and the rear blade chamber.

It is preferable that the first area of the opening is smaller than half of the total area of the opening, and the second area of the opening is larger than half of the total area of the opening.

The at least one rear blade may include a first rear blade that enters the opening first when moving from the second retracted position to the second closed position, and a second rear blade that enters the opening following the first rear blade when moving from the second retracted position to the second closed position. In this case, it is preferable that the first partition plate and the second partition plate are arranged to face each other in the blade running direction near an area where the first rear blade and the second rear blade overlap at the second closed position.

According to a second aspect of the present invention, there is provided an imaging device including the above-mentioned blade drive device and an imaging element arranged on a surface on which light transmitted through the openings of the pair of base plates of the blade drive device forms an image.

Though we have described preferred embodiments of the present invention, it goes without saying that the present invention is not limited to the above-mentioned embodiments and may be embodied in various different forms within the scope of its technical concept.

REFERENCE SIGNS LIST 1 Blade drive device 10, 12 Base plate 11, 13 Circular arc hole 21-24 Rotating shaft 31-34 Leading blade 35-38 Trailing blade 41, 42 Leading blade arm 43, 44 Trailing blade arm 45, 46 Connecting portion 51 First partition plate 52 Second partition plate 61 Leading blade drive lever 62 Trailing blade drive lever 511, 521 Frame portion 512, 522 Arm portion G Dividing position R1 Leading blade chamber R2 Trailing blade chamber S Opening portion S1 First region S2 Second region

Claims (5)

A pair of base plates having openings formed therein;
at least one leading blade movable between a first closing position that closes the opening and a first retracted position that is located on the blade running direction side of the opening;
at least one rear blade movable between a second retracted position located on the opposite side of the opening in the blade travel direction and a second closing position that closes the opening;
a partition portion that divides a space formed between the pair of base plates into a leading blade chamber that houses the leading blade and a trailing blade chamber that houses the trailing blade,
The partition portion is
a first partition plate extending around a periphery of a first region located on the blade travel direction side of the opening;
a second partition plate extending around a periphery of a second region located on an opposite side of the opening with respect to the blade travel direction,
Blade drive device. The blade drive device according to claim 1, wherein at least one of the material and thickness of the first partition plate and the second partition plate is different. the first area of the opening is less than half of a total area of the opening;
the second area of the opening is greater than half of the total area of the opening;
The blade drive device according to claim 1 or 2. The at least one rear wing is
a first rear blade that enters the opening first when moving from the second retracted position to the second closing position;
a second rear blade that enters the opening following the first rear blade when moving from the second retracted position to the second closing position,
the first partition plate and the second partition plate are disposed to face each other in the blade running direction near a region where the first rear blade and the second rear blade overlap at the second closing position.
The blade drive device according to claim 3 . The blade drive device according to any one of claims 1 to 4,
an imaging element disposed on a surface on which an image is formed by light transmitted through the openings of the pair of base plates of the blade drive device.

Images