Focal Plane Shutter

Abstract

To provide a focal plane shutter which includes blades and hardly transmits shock due to blade drive to the outside and can materialize compact structure.SOLUTION: A focal plane shutter 1 comprises: a bottom board 10 in which an opening S is formed; blades 31, 32 which are movable in such a way as to open and close the opening S of the bottom board 10; blade arms 41-44 which are connected to the blades 31, 32; and a drive unit 20 driving the blades 31, 32. The drive unit 20 includes a base 21, drive shafts 22, 23 attached to the base 21, and drive levers 71, 72 which have arm connections 71C, 72C connected to the blade arms 41-44 and can rotate around the drive shafts 22, 23. The focal plane shutter 1 further comprises a shock absorption member 80 which is located between the bottom board 10 and the base 21 of the drive unit 20.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a focal plane shutter, and more particularly to a focal plane shutter for an imaging device having at least one blade. [Background technology]

[0002] In an imaging device such as a camera, an exposure aperture is opened and closed by moving a shutter blade at high speed to expose an imaging element. Conventionally, a focal plane shutter, which moves the shutter blade at high speed in one direction by an actuator, has been known as a blade driving device for driving the shutter blade. In such a focal plane shutter, a buffer member is arranged at the end of the movement path of a driving unit that drives the shutter blade in order to prevent the shutter blade from bouncing or being damaged by the impact when the shutter blade is driven at high speed (for example, see Patent Document 1).

[0003] However, even when such a buffer member is provided, it is difficult to sufficiently prevent the shock generated when the shutter blades are driven at high speed from being transmitted from the base plate of the focal plane shutter to the camera housing via the actuator drive shaft. If a shock is applied to the camera body, it will adversely affect the captured image, so in order to reduce the transmission of such a shock to the camera housing, it is possible to provide a shock absorbing mechanism between the focal plane shutter and the camera housing, but in this case the overall size of the camera will increase. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-64559 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the problems with the conventional technology, and has as its object to provide a focal plane shutter which is capable of realizing a compact structure and which is less susceptible to the transmission of shocks caused by the driving of the blades to the outside. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a focal plane shutter that is compact in structure and does not easily transmit shocks caused by driving of the blades. The focal plane shutter includes a base plate having an opening, at least one blade movable to open and close the opening of the base plate, an arm connected to the at least one blade, and a drive unit that drives the at least one blade. The drive unit includes a base, a drive shaft attached to the base, and a drive lever having an arm connecting portion connected to the arm and rotatable about the drive shaft. The focal plane shutter further includes a shock absorbing member disposed between the base plate and the base of the drive unit. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a front view showing a focal plane shutter according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of the focal plane shutter shown in FIG. [Diagram 3] FIG. 3 is an enlarged perspective view showing some components of the focal plane shutter shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of a focal plane shutter according to the present invention will be described in detail with reference to Figs. 1 to 3. In Figs. 1 to 3, identical or corresponding components are denoted with the same reference numerals, and duplicated explanations will be omitted. In addition, in Figs. 1 to 3, the scale and dimensions of each component may be exaggerated, and 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.

[0009] FIG. 1 is a front view showing a focal plane shutter 1 according to an embodiment of the present invention. As shown in FIG. 1, the focal plane shutter 1 according to this embodiment includes a base plate 10 in which a rectangular opening S is formed, six blades 31, 32 housed in a space (blade chamber) formed between the base plate 10 and a cover plate (not shown), and a drive unit 20 for driving (moving) these blades 31, 32. An opening of substantially the same shape as the opening S of the base plate 10 is formed in the cover plate, and an exposure opening is formed by the opening S of the base plate 10 and the opening of the cover plate. This focal plane shutter 1 is incorporated in a camera equipped with an imaging element (not shown) such as a CCD or CMOS sensor, and is fixed to a camera body (not shown) by, for example, inserting a screw into a fixing hole 2. The imaging element is located on the front side of the focal plane shutter 1 in FIG. 1, and light from a subject passes through the above-mentioned exposure opening and enters the imaging element on the front side of the paper.

[0010] Each of the blades 31 and 32 is a thin plate-like member extending in the X direction as a whole. In this embodiment, three blades 31 are stacked in the Z direction to form the rear curtain (rear blades) of the focal plane shutter 1. Also, three blades 32 are stacked in the Z direction to form the front curtain (front blades) of the focal plane shutter 1.

[0011] The focal plane shutter 1 also includes rear blade arms 41, 42 (arm portions) connected to the rear blade 31. Each rear blade 31 is connected to each rear blade arm 41, 42 by a connecting portion 51 so as to be rotatable with respect to each other. The rear blade arm 41 is configured to be rotatable about a support shaft 61, and the rear blade arm 42 is configured to be rotatable about a support shaft 62. With this configuration, each rear blade 31 and each rear blade arm 41, 42 form a link mechanism.

[0012] Similarly, the focal plane shutter 1 includes leading blade arms 43, 44 (arm portions) connected to the leading blade 32. Each leading blade 32 is connected to each leading blade arm 43, 44 by a connecting portion 52 so as to be rotatable with respect to each other. The leading blade arm 43 is configured to be rotatable about a support shaft 63, and the leading blade arm 44 is configured to be rotatable about a support shaft 64. With this configuration, each leading blade 32 and each leading blade arm 43, 44 forms a link mechanism.

[0013] Fig. 2 is an exploded perspective view of the focal plane shutter 1. As shown in Fig. 2, the drive unit 20 of the focal plane shutter 1 includes a plate-shaped base 21, drive shafts 22, 23 and a rotating shaft 24 extending from the base 21 in the +Z direction, a trailing blade drive lever 71 rotatably attached to the drive shaft 22, a leading blade drive lever 72 rotatably attached to the drive shaft 23, a control lever 73 rotatably attached to the rotating shaft 24 and capable of controlling the rotation of the trailing blade drive lever 71 and the leading blade drive lever 72, a cover plate 74 covering the trailing blade drive lever 71, the leading blade drive lever 72 and the control lever 73, and a fixed shaft 75 attached to the cover plate 74. The drive shaft 22 is provided coaxially with the support shaft 61 (see Fig. 1), and the drive shaft 23 is provided coaxially with the support shaft 63 (see Fig. 1).

[0014] Between the base 21 of the drive unit 20 and the base plate 10, a shock absorbing member 80 made of a flexible material such as butyl rubber or elastomer is disposed. A recess 12 having a shape corresponding to the shape of the shock absorbing member 80 is formed in the base plate 10, and the shock absorbing member 80 is accommodated in the recess 12 of the base plate 10. For example, the thickness of most of the shock absorbing member 80 in the Z direction is about 0.5 mm, and the depth of the recess 12 of the base plate 10 in the Z direction is about 0.5 mm.

[0015] As shown in FIG. 2, the fixed shaft 75 attached to the cover plate 74 is inserted into the shaft hole 27 formed in the base 21 and protrudes from the base 21 in the -Z direction. The shock absorbing member 80 has clearances 86 and 87 for passing the fixed shaft 75 extending from the base 21 in the -Z direction. As shown in FIG. 3, the clearances 86 and 87 of the shock absorbing member 80 allow the fixed shaft 75 extending from the base 21 in the -Z direction to be fixed to the base plate 10 without coming into contact with the shock absorbing member 80. For example, a screw (not shown) is inserted into the circular hole 17 of the base plate 10 from the -Z direction side, and the drive unit 20 is fixed to the base plate 10 by screwing the screw into the end of the fixed shaft 75 on the -Z direction side. In this way, the fixed shaft 75 can be fixed to the base plate 10 without coming into contact with the flexible shock absorbing member 80, so that the drive unit 20 can be firmly fixed to the base plate 10.

[0016] The rear blade drive lever 71 has a shaft portion 71A through which the drive shaft 22 is inserted, an attraction portion 71B which is attracted to an electromagnet (not shown), and an arm connection portion 71C which is inserted into a lever hole 41A (see FIG. 1) formed in the rear blade arm 41 and connected to the rear blade arm 41. The base portion 21 is formed with an arc hole 25 along an arc centered on the drive shaft 22, and the base plate 10 is also formed with an arc hole 13 along an arc centered on the drive shaft 22. The shock absorbing member 80 is also formed with an arc hole 81 along an arc centered on the drive shaft 22. The arm connection portion 71C of the rear blade drive lever 71 is connected to the lever hole 41A of the rear blade arm 41 through these arc holes 25, 81, 13.

[0017] The leading blade drive lever 72 has a shaft portion 72A through which the drive shaft 23 is inserted, an attraction portion 72B which is attracted to an electromagnet (not shown), and an arm connection portion 72C which is inserted into a lever hole 43A (see FIG. 1) formed in the leading blade arm 43 and connected to the leading blade arm 43. A notch 26 is formed in the base portion 21 along an arc centered on the drive shaft 23, and an arc hole 14 is formed in the base plate 10 along an arc centered on the drive shaft 23. A notch 82 is also formed in the shock absorbing member 80 along an arc centered on the drive shaft 23. The arm connection portion 72C of the leading blade drive lever 72 is connected to the lever hole 43A of the leading blade arm 43 through these notches 26, 82 and the arc hole 14.

[0018] In this configuration, when the rear blade drive lever 71 is rotated around the drive shaft 22, the rear blade arm 41 connected to the arm connection part 71C of the rear blade drive lever 71 rotates around the support shaft 61. When the rear blade arm 41 rotates around the support shaft 61, the above-mentioned link mechanism causes the rear blade arm 42 to also rotate around the support shaft 62, and the rear blades 31 move mainly in the ±Y direction on the XY plane while changing the overlapping areas.

[0019] The trailing blade drive lever 71 is rotated to a charge position on the +Y direction side by the control lever 73, and the attraction portion 71B is attracted to the electromagnet at the charge position, thereby holding the trailing blade drive lever 71 at the charge position. After that, when the control lever 73 returns to the initial position and the power supply to the electromagnet is cut off, the trailing blade drive lever 71 rotates toward the blade travel completion position by the force of a drive spring (not shown), and accordingly the trailing blade 31 moves mainly in the -Y direction.

[0020] Similarly, when the leading blade drive lever 72 is rotated around the drive shaft 23, the leading blade arm 43 connected to the arm connection portion 72C of the leading blade drive lever 72 rotates around the support shaft 63. When the leading blade arm 43 rotates around the support shaft 63, the leading blade arm 44 also rotates around the support shaft 64 due to the above-mentioned link mechanism, and the leading blades 32 move mainly in the ±Y directions on the XY plane while changing the overlapping areas.

[0021] The leading blade drive lever 72 is rotated to a charge position on the +Y direction side by the control lever 73, and the adsorption portion 72B is attracted to the electromagnet at the charge position, thereby holding the leading blade drive lever 72 at the charge position. After that, when the control lever 73 returns to the initial position and the power supply to the electromagnet is cut off, the leading blade drive lever 72 rotates toward the blade travel completion position by the force of a drive spring (not shown), and accordingly the leading blade 32 moves mainly in the -Y direction.

[0022] It is known that when the drive levers 71 and 72 rotate from the charge position to the blade travel completion position, a particularly strong impact is applied to the drive shafts 22 and 23. This impact is transmitted to the base 21 on which the drive shafts 22 and 23 are provided, but in this embodiment, since the impact absorbing member 80 is disposed between the base 21 and the base plate 10, the impact transmitted to the base 21 is absorbed by the impact absorbing member 80 and is not easily transmitted to the base plate 10. Therefore, the impact caused by the drive of the drive levers 71 and 72 is not easily transmitted from the base plate 10 to the outside (camera body), and the image to be captured is less likely to be adversely affected. In addition, since the impact caused by the drive of the drive levers 71 and 72 can be absorbed inside the focal plane shutter 1, there is no need to provide a mechanism for absorbing the impact outside the focal plane shutter 1, and the structure of the entire camera can be made compact.

[0023] Furthermore, if a mechanism for absorbing impact is provided outside the focal plane shutter 1, there is a possibility that a misalignment may occur between the base plate of the focal plane shutter that receives the impact and the image sensor of the camera where the impact is absorbed, which may adversely affect the captured image. However, in this embodiment, the impact transmitted to the base plate 10 of the focal plane shutter 1 is absorbed, thereby preventing a misalignment from occurring between the base plate 10 of the focal plane shutter 1 and the image sensor of the camera.

[0024] 2, an end of the arc hole 81 formed in the shock absorbing member 80 is formed thick, and an arc-shaped damper portion 83 is formed at the terminal end of the arc hole 81. When the arm connecting portion 71C of the trailing blade drive lever 71 rotating toward the blade travel completion position hits this damper portion 83, the shock when the trailing blade drive lever 71 stops is absorbed and mitigated by the damper portion 83, so that the shock transmitted to the base plate 10 can be further reduced. Note that damper accommodating portions 13A and 25A for accommodating the damper portion 83 of the shock absorbing member 80 are formed at the end on the -Y direction side of the arc hole 13 formed in the base plate 10 and the end on the -Y direction side of the arc hole 25 formed in the base 21, respectively.

[0025] Similarly, the end of the notch 82 formed in the shock absorbing member 80 is formed thick, and an arc-shaped damper portion 84 is formed at the end of the notch 82. When the arm connecting portion 72C of the leading blade drive lever 72 rotating toward the blade travel completion position hits this damper portion 84, the shock when the leading blade drive lever 72 stops is absorbed and mitigated by the damper portion 84, so that the shock transmitted to the base plate 10 can be further reduced. Note that damper accommodating portions 14A and 26A for accommodating the damper portion 84 of the shock absorbing member 80 are formed at the end of the -Y direction side of the arc hole 14 formed in the base plate 10 and the end of the -Y direction side of the notch 26 formed in the base 21, respectively.

[0026] Furthermore, since these damper portions 83, 84 are configured as part of the shock absorbing member 80, the shock associated with driving the drive levers 71, 72 is absorbed not only by the damper portions 83, 84 but also by other portions of the shock absorbing member 80, so that the shock associated with driving the drive levers 71, 72 can be more effectively mitigated.

[0027] Moreover, the base plate 10 in this embodiment has two positioning protrusions 15 that protrude toward the base 21 of the drive unit 20. Correspondingly, the shock absorbing member 80 is formed with positioning holes 85 that accommodate the positioning protrusions 15 of the base plate 10. With this configuration, the shock absorbing member 80 can be accurately positioned with respect to the base plate 10 simply by aligning the positioning protrusions 15 formed on the base plate 10 with the positioning holes 85 of the shock absorbing member 80 and inserting the positioning protrusions 15 of the base plate 10 into the positioning holes 85 of the shock absorbing member 80.

[0028] Furthermore, as described above, in this embodiment, the impact absorbing member 80 is housed within the recess 12 formed in the base plate 10, so that the impact absorbing member 80 can be disposed between the base 21 of the drive unit 20 and the base plate 10 without excessively increasing the thickness of the focal plane shutter 1 in the Z direction.

[0029] The material, shape, size, thickness, and degree of compression between the base 21 of the drive unit 20 and the base plate 10 of the shock absorbing member 80 can be appropriately changed in accordance with parameters such as the size of the exposure opening of the focal plane shutter 1 and the speed of the blades 31 and 32.

[0030] As described above, according to one aspect of the present invention, there is provided a focal plane shutter that is capable of realizing a compact structure and that is less susceptible to the transmission of shocks caused by the driving of the blades to the outside. The focal plane shutter includes a base plate having an opening, at least one blade that is movable to open and close the opening of the base plate, an arm portion connected to the at least one blade, and a drive unit that drives the at least one blade. The drive unit includes a base portion, a drive shaft attached to the base portion, and a drive lever that has an arm connecting portion connected to the arm portion and is rotatable around the drive shaft. The focal plane shutter further includes a shock absorbing member disposed between the base plate and the base portion of the drive unit.

[0031] According to this configuration, a strong shock generated when the drive lever is driven is transmitted to the base of the drive unit, but since a shock absorbing member is disposed between the base plate and the base, the shock transmitted to the base is absorbed by the shock absorbing member and is not easily transmitted to the base plate. This results in a structure in which the shock caused by the drive of the drive lever is not easily transmitted from the base plate to the outside (such as the camera body). In this way, since the shock caused by the drive lever being driven can be mitigated inside the focal plane shutter, there is no need to provide a mechanism for mitigating the shock outside the focal plane shutter, and a compact structure can be realized.

[0032] The shock absorbing member preferably has a damper portion that comes into contact with the drive lever of the drive unit to absorb the shock when the drive lever stops. When the drive lever comes into contact with such a damper portion, the shock when the drive lever stops is absorbed and absorbed by the damper portion, so that the shock transmitted to the base plate can be further reduced. In particular, since the damper portion is configured as a part of the shock absorbing member, the shock caused by the drive of the drive lever is absorbed not only by the damper portion but also by other parts of the shock absorbing member, so that the shock caused by the drive of the drive lever can be more effectively absorbed.

[0033] The drive unit may further include at least one fixed shaft attached to the base. In this case, it is preferable that the shock absorbing member has a recess for passing the at least one fixed shaft and fixing the shock absorbing member to the base plate. The recess of the shock absorbing member allows the fixed shaft attached to the base plate to be fixed to the base plate without contacting the shock absorbing member, so that the drive unit can be firmly fixed to the base plate.

[0034] The base plate may have at least one positioning protrusion protruding toward the base of the drive unit. The shock absorbing member may have a positioning hole for accommodating the at least one positioning protrusion of the base plate. With this configuration, the shock absorbing member can be accurately positioned with respect to the base plate by simply aligning the protrusion formed on the base plate with the positioning hole of the shock absorbing member and inserting the protrusion of the base plate into the positioning hole of the shock absorbing member.

[0035] Furthermore, a recess may be formed in the base plate, and the shock absorbing member may be accommodated in the recess of the base plate. By accommodating the shock absorbing member in the recess formed in the base plate in this manner, the shock absorbing member can be disposed between the base of the drive unit and the base plate without excessively increasing the thickness of the focal plane shutter.

[0036] Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and may be embodied in various different forms within the scope of the technical concept thereof. [Explanation of symbols]

[0037] 1 Focal plane shutter 10 Main plate 12 Recess 13,14 Arc hole 15 Positioning protrusion 20 Drive unit 21 Base 22,23 Drive shaft 24 Rotational Axis 25 Arc hole 26 Notch 27 Shaft hole 31 Rear wing 32 Leading Blade 41,42 Rear wing arm (arm part) 43,44 Front blade arm (arm section) 51,52 Connecting part 61~64 Support shaft 71 Rear blade drive lever 71A Shaft 71B Adsorption part 71C Arm connection part 72 Leading blade drive lever 72A Shaft 72B Adsorption part 72C Arm connection part 73 Control Lever 74 Cover plate 75 Fixed axis 80 Shock absorbing material 81 Arc hole 82 Notch 83,84 Damper section 85 Positioning hole 86,87 Relief section S opening

Claims

1. A base plate having an opening formed therein; At least one blade movable to open and close the opening in the base plate; An arm portion connected to the at least one blade; A drive unit for driving the at least one blade, A base and A drive shaft attached to the base; a drive lever having an arm connecting portion connected to the arm portion and rotatable about the drive shaft; A drive unit including: an impact absorbing member disposed between the base plate and the base of the drive unit; The focal plane shutter comprises:

2. 2. The focal plane shutter according to claim 1, wherein the shock absorbing member has a damper portion that comes into contact with the drive lever of the drive unit to absorb the shock when the drive lever stops.

3. The drive unit further includes at least one fixed shaft attached to the base; The impact absorbing member is provided with a recess for allowing the at least one fixed shaft to pass therethrough and for fixing the impact absorbing member to the base plate.

3. The focal plane shutter according to claim 1 or 2.

4. the base plate has at least one positioning protrusion protruding toward the base of the drive unit; The shock absorbing member is formed with a positioning hole for receiving the at least one positioning protrusion of the main plate.

4. The focal plane shutter according to claim 1.

5. A recess is formed in the base plate, The shock absorbing member is accommodated in the recess of the main plate. The focal plane shutter according to any one of claims 1 to 4.

Images