Blade-driving device, optical device, and method for producing arm

This application is a continuation of and claims priority to International Patent Application No. PCT/JP2013/078870 filed on Oct. 24, 2013, which claims priority to Japanese Patent Application No. 2012-241983 filed on Nov. 1, 2012, subject matter of these patent documents is incorporated by reference herein in its entirety.

(i) Technical Field

The present invention relates to blade-driving devices, optical devices and methods for producing arms.

(ii) Related Art

There is known a device in which a blade opens and closes an opening of a board. Such a device includes an arm for driving the blade and a drive member for driving the arm. Japanese Unexamined Patent Application Publication No. 07-168248 discloses an arm attached with a reinforcement member.

Depending on a thickness or a material of the reinforcement member, the reinforcement member might be partially peeled off from the arm.

According to an aspect of the present invention, there is provided a blade-driving device includes: a board including an opening; a blade opening and closing the opening; an arm driving the blade and made of a synthetic resin; a drive member driving the arm; and a reinforcement member formed with a laser welding mark indicating a mark formed by laser welding the reinforcement member and the arm together, and made of a synthetic resin.

FIG. 1 is a front view of inner structure of a focal-plane shutter according to the present embodiment;

FIG. 2 is an external perspective view of the focal-plane shutter;

FIG. 3 is a sectional view taken along line A-A of FIG. 1 ;

FIG. 4 is an enlarged view of a board and arms;

FIG. 5 is an enlarged view of the arm; and

FIG. 6 is an explanatory view of a variation of a laser welding mark.

In the present embodiment, a focal-plane shutter 1 will be described as an example of a blade-driving device. FIG. 1 is a front view of inner structure of the focal-plane shutter 1 according to the present embodiment. FIG. 2 is an external perspective view of the focal-plane shutter 1 . The focal-plane shutter 1 is employed in an optical instrument such as a digital camera or a still camera. The focal-plane shutter 1 includes a board 10 , a leading blade 20 A, a trailing blade 20 B, arms 31 a , 32 a , 31 b , and 32 b , drive members 40 a and 40 b , output members 50 a and 50 b , and rotors 72 a and 72 b . Additionally, the rotors 72 a and 72 b , and the output members 50 a and 50 b are omitted in FIG. 1 . The board 10 includes an opening 11 . The leading blade 20 A and the trailing blade 20 B open and close the opening 11 . The rotor 72 a is included in an actuator for driving the leading blade 20 A. The rotor 72 b is included in an actuator for driving the trailing blade 20 B. Each actuator includes a stator around which a coil is wound, and is omitted in FIGS. 1 and 2 .

The leading blade 20 A includes plural blades 21 a to 23 a . The trailing blade 20 B also includes plural blades. Each of the leading blade 20 A and the trailing blade 20 B can shift between an overlapped state where the plural blades overlap one another and an expanded state where the plural blades are expanded. These plural blades recede from the opening 11 in the overlapped state to bring the opening 11 into a fully opened state. These plural blades close the opening 11 in the expanded state to bring the opening 11 into a fully closed state. FIGS. 1 and 2 illustrate the state where the expanded leading blade 20 A closes the opening 11 and the trailing blade 20 B recedes from the opening 11 .

The leading blade 20 A is connected to the arms 31 a and 32 a . The trailing blade 20 B is connected to the arms 31 b and 32 b . As illustrated in FIG. 1 , the arms 31 a , 32 a , 31 b , and 32 b are rotatably supported by spindles 14 a , 15 a , 14 b , and 15 b provided in the board 10 , respectively.

The drive members 40 a and 40 b drive the arms 31 a and 31 b , respectively. The drive members 40 a and 40 b are provided with drive pins 43 a and 43 b connected to the arms 31 a and 31 b , respectively. The board 10 is formed with escape slots 13 a and 13 b for permitting the movement of the drive pins 43 a and 43 b , respectively. The drive members 40 a and 40 b will be described later in detail. The rotors 72 a and 72 b are respectively connected to the output members 50 a and 50 b . The rotation of the rotors 72 a and 72 b rotates the output members 50 a and 50 b , so the drive members 40 a and 40 b rotates, which drives the leading blade 20 A and the trailing blade 20 B, respectively. The positions of rotational axes of the output members 50 a and 50 b and the drive members 40 a and 40 b are different from one another. Additionally, the output members 50 a and 50 b and the drive members 40 a and 40 b are respectively formed with gear portions 55 a , 55 b , 45 a , and 45 b . The gear portions 55 a and 45 a mesh with each other, and the gear portions 55 b and 45 b mesh with each other, so that the rotation of the output members 50 a and 50 b respectively rotate the drive members 40 a and 40 b.

As illustrated FIG. 2 , the board 10 is formed with a positioning portion 19 a near one end of the escape slot 13 a . Likewise, a positioning portion 19 b is formed near one end of the escape slot 13 b . The other ends of the escape slots 13 a and 13 b are provided with rubbers Ga and Gb for absorbing the impact of the drive members 40 a and 40 b , respectively. In addition, the board 10 is assembled with a holder holding the above actuators not illustrated.

As illustrated in FIG. 1 , connection pins Pa 1 to Pa 3 connect the arm 31 a with the leading blade 20 A. Connection pins Pb 1 to Pb 3 connect the arm 31 b with the trailing blade 20 B. Also, the arm 32 a is connected with the leading blade 20 A by connection pins without reference numerals. Likewise, the arm 32 b is connected with the trailing blade 20 B by connection pins. The connection pins Pa 1 to Pa 3 and Pb 1 to Pb 3 have the same shape and the same size.

FIG. 3 is a sectional view taken along line A-A of FIG. 1 . In addition, in FIG. 3 , the arm 31 a , the connection pins Pa 1 to Pa 3 , and the blades 21 a to 23 a are illustrated, but the board 10 and the like are omitted. The connection pins Pa 1 to Pa 3 connect the respective blades 21 a to 23 a with the arm 31 a . The arm 31 a is bonded with a reinforcement member 31 A. This will be described later in detail.

Next, the arms 31 a and 31 b will be described. FIG. 4 is an enlarged view of the board 10 , and the arms 31 a and 31 b . In addition, FIG. 4 illustrates the arm 31 a in a state where the leading blade 20 A recedes from the opening 11 . The arm 31 a is formed with: through holes h 1 to h 3 through which the connection pins Pa 1 to Pa 3 respectively penetrate; and an insertion hole h 4 into which the drive pin 43 a of the drive member 40 a is inserted. The arm 31 a is partially bonded with the reinforcement member 31 A. Also, the arm 31 b is partially bonded with a reinforcement member 31 B. This ensures the rigidity of the arms 31 a and 31 b , thereby preventing from being bent and damaged. Herein, the arms 31 a and 31 b have the same shape, the same size, and the same material. Likewise, the reinforcement members 31 A and 31 B have the same shape, the same size, and the same material. The arms 31 a and 31 b each has a thin plate shape, and the reinforcement members 31 A and 31 B each has a thin plate shape. The arm 31 a and the reinforcement member 31 A are made of synthetic resins. In FIG. 4 , the reinforcement member 31 A is bonded on a rear side of the arm 31 a , and the reinforcement member 31 B is bonded on a front side of the arm 31 b.

FIG. 5 is an enlarged view of the arm 31 a . FIG. 5 illustrates the movable directions DA and DB of the drive pin 43 a , inserting into the insertion hole h 4 , of the drive member 40 a . Since the drive member 40 a reciprocally rotates in a predetermined range, the drive pin 43 a moves in the opposite directions. The reinforcement member 31 A is bonded to the arm 31 a by laser welding. FIG. 5 illustrates a laser welding mark L indicating a mark of the laser welding to bond the reinforcement member 31 A to the arm 31 a . The through hole h 3 having the same size is commonly formed in the arm 31 a and the reinforcement member 31 A, and the insertion hole h 4 having the same size is commonly formed therein. The reinforcement member 31 A is bonded to the arm 31 a by laser welding, so the bonding strength can be ensured, even in a case where the reinforcement member 31 A is thin. For example, in a case where the reinforcement member 31 A is bonded to the arm 31 a by adhesive bonding, this might arise a problem such as the leakage of the excess adhesive bond into the insertion hole h 4 . In the present embodiment, the bonding is achieved by laser bonding, thereby solving such a problem.

The laser welding mark L includes: a region L 1 extending in such a direction as to arrange two of the through hole h 3 and the insertion hole h 4 ; a region L 2 curving from the region L 1 to surround the periphery of the insertion hole h 4 ; and a region L 3 extending from the region L 2 in such a direction as to arrange the insertion hole h 4 and the through hole h 3 . The regions L 1 and L 3 are positioned to sandwich two of the through hole h 3 and the insertion hole h 4 . The laser welding mark L entirely has a substantially S-shape, and meanders. This ensures the length of the laser welding mark L relative to the area of the reinforcement member 31 A, thereby ensuring the bonding strength between the reinforcement member 31 A and the arm 31 a . Further, the laser welding mark L has a linearly shape, so the workability of the laser welding is facilitated.

The shape of the insertion hole h 4 will be described. The through hole h 3 has a circular shape, whereas the insertion hole h 4 has an oblong hole shape extending radially from a support spindle hole h 5 . The support spindle hole h 5 is inserted by the spindle 14 a , and the arm 31 a is rotatably supported about the spindle 14 a . The insertion hole h 4 includes: edge portions h 41 and h 43 facing each other and serving as short sides; and edge portions h 42 and h 44 facing each other and serving as long sides. The edge portions h 41 and h 43 curve. The edge portions h 42 and h 44 have linearly shapes. The region L 2 of the laser welding mark L is evenly spaced from the edge portion h 42 and parallel thereto. In addition, the shape of the drive pin 43 a corresponds to that of the insertion hole h 4 .

For example, while the drive member 40 a is rotating and the drive pin 43 a is moving in the movable direction DA, the periphery of the insertion hole h 4 , specifically, the edge portion h 42 receives the force from the drive pin 43 a in the movable direction DA. In the present embodiment, the region L 2 of the laser welding mark L intersects with the direction in which the periphery of the insertion hole h 4 receives the force from the drive pin 43 a , that is, the movable direction DA of the drive pin 43 a , while the drive pin 43 a is moving in the movable direction DA. Thus, the parts, of the arm 31 a and the reinforcement member 31 A, tending to receive the force from the drive pin 43 a are bonded by laser welding. This prevents the reinforcement member 31 A from being peeled off from the arm 31 a , and the bonding strength therebetween.

For example, in a case where the distance is partially uneven between the region L 2 and the edge portion h 42 tending to receive the force, that is, the region L 2 is not evenly spaced from the edge portion h 42 , the reinforcement member 31 A might be partially peeled off from the arm 31 a around the edge portion h 42 . In the present embodiment, the region L 2 is formed to be evenly spaced from the edge portion h 42 that tends to receive the force from the drive pin 43 a . This prevents the reinforcement member 31 A from being peeled off from the arm 31 a around the edge portion h 42 .

Further, in the present embodiment, in order not to cause the force to focus on one point from the drive pin 43 a in the movable direction DA when the drive member 40 a abuts with the end of the escape slot, the edge portion h 42 has a linear shape corresponding to the shape of the drive pin 43 a . This prevents the reinforcement member 31 A from being peeled off from the arm 31 a , and also prevents the damage to the arm 31 a and the reinforcement member 31 A.

Furthermore, as illustrated in FIG. 5 , the religions L 1 , L 2 , and L 3 of the laser welding mark L surround one half or more of the periphery of the insertion hole h 4 . It is therefore possible to ensure the bonding strength around the insertion hole h 4 to which the load tends to be applied due to the movement of the drive pin 43 a.

Moreover, the reinforcement member 31 A is formed with the through hole h 3 , and as indicated by the laser welding mark L, a part of the arm 31 a around the through hole h 3 is also reinforced. Further, an increase in size of the reinforcement member 31 A relative to the arm 31 a ensures the length of the L. Also, the through hole h 3 is formed closest, among the through holes h 1 to h 3 , to the rotation fulcrum of the arm 31 a . This increases the area of the reinforcement member 31 A, and ensures the bonding strength around the insertion hole h 4 to which the load tends to be applied due to the movement of the drive pin 43 a.

Further, as mentioned above, the connection pins Pa 1 to Pa 3 and Pb 1 to Pb 3 have the same shape and the same size. For this reason, in a case of the reinforcement member in the present embodiment is employed in another focal-plane shutter, the conventional connection pins can be used, so the bonding strength between the arm and the reinforcement member can be ensured without using a special connection pin.

Also, as illustrated in FIG. 3 , the reinforcement member 31 A has a thin plate shape thinner than the arm 31 a . Thus, the reinforcement member 31 A can be appropriately bonded to the arm 31 a by laser welding.

Additionally, as illustrated in FIG. 3 , the reinforcement member 31 A is provided on the surface, of the arm 31 a , opposite to the surface facing the blades 21 a to 23 a . Therefore, this makes it possible to prevent the abutment of the edge of the outer peripheral shape with the blades 21 a to 23 a . It is thus possible to appropriately reinforce the arm while the steady movements of the blades 21 a to 23 a are ensured.

FIG. 6 is an explanatory view of a variation of a laser welding mark. A laser welding mark L′ includes: a region L 2 ′ curving; a region L 4 ′ extending to sandwich the insertion hole h 4 between the region L 2 ′ and the region L 4 ′. The region L 4 ′ extends between the insertion hole h 4 and the through hole h 3 . The region L 2 ′ intersects with the movable direction DA of the drive pin 43 a , so the parts, of the arm 31 a and the reinforcement member 31 A, tending to receive the force from the drive pin 43 a are bonded by laser welding. Further, the region L 4 ′ intersects with the movable direction DB of the drive pin 43 a , so parts, of the arm 31 a and the reinforcement member 31 A, tending to receive the force from the drive pin 43 a are bonded by laser welding. This ensures the bonding strength therebetween.

Also, the reinforcement member 31 A and the arm 31 a may be laser welded so as to include the region L 2 parallel to the edge portion h 42 illustrated in FIG. 5 , and the region L 4 ′ parallel to the edge portion h 44 illustrated in FIG. 6 . The arm 31 b and the reinforcement member 31 B may be formed with the laser welding mark L illustrated in FIG. 5 , or the laser welding mark L′ illustrated in FIG. 6 . In addition, laser welding marks may be formed in the opposite sides so as to be evenly spaced from respective linearly edge portions.

Next, a description will be given of a method for producing the arm 31 a by laser welding. The arm 31 a and the reinforcement member 31 A separately formed beforehand are positioned by jigs. Specifically, the arm 31 a and the reinforcement member 31 A are overlapped such that the through hole h 3 and the insertion hole h 4 of the arm 31 a positionally and respectively correspond to the through hole h 3 and the insertion hole h 4 of the reinforcement member 31 A, and the through hole h 3 and the insertion hole h 4 are inserted by respective rod-shaped jigs. Two holes having the same shape and the same size are inserted by the rod-shaped jigs, so the arm 31 a and the reinforcement member 31 A are positioned relative to each other. In this way, two of the arm 31 a and the reinforcement member 31 A are positioned by use of the through hole h 3 and the insertion hole h 4 , whereby the positioning is facilitated. Next, the arm 31 a and the reinforcement member 31 A are laser welded by a laser welding device.

The arm 31 a is produced in this way. After laser welding, the arm 31 a is connected to the blade 21 a to 23 a by the common connection pins Pa 1 to Pa 3 and is assembled to the board 10 , and the drive pin 43 a of the drive member 40 a is inserted into the insertion hole h 4 . After that, the board 10 is assembled with the output member 50 a and the rotor 72 a , so the focal-plane shutter 1 is produced.

While the exemplary embodiments of the present invention have been illustrated in detail, the present invention is not limited to the above-mentioned embodiments, and other embodiments, variations and modifications may be made without departing from the scope of the present invention.

In the present embodiment, the leading blade 20 A and the trailing blade 20 B are driven by use of the actuators. However, the present invention is not limited to this. For example, the operation of an electromagnet and a spring may drive the blade through the drive member.

Further, the present embodiment has described the focal-plane shutter 1 , but the present invention is not limited to this configuration. For example, it may be a blade-driving device for opening and closing an opening of a board by a single blade.

Finally, several aspects of the present invention are summarized as follows.

According to an aspect of the present invention, there is provided a blade-driving device includes: a board including an opening; a blade opening and closing the opening; an arm driving the blade and made of a synthetic resin; a drive member driving the arm; and a reinforcement member formed with a laser welding mark indicating a mark formed by laser welding the reinforcement member and the arm together, and made of a synthetic resin. The bonding of the synthetic resin-made reinforcement member to the synthetic resin-made arm by laser welding can ensure the bonding strength therebetween.

According to another aspect of the present invention, there is provided an optical device including the above blade-driving device.

According to another aspect of the present invention, there is provided a method for producing an arm for driving a blade opening and closing an opening of a board, including: commonly inserting a jig into insertion holes respectively formed in an arm and a reinforcement member; inserting a jig into through holes respectively formed in the arm and the reinforcement member and different from the insertion holes; and laser welding the arm and the reinforcement member.