JP2019032570A - Focal plane shutter for camera and camera - Google Patents

Abstract

To provide a focal plane shutter for camera capable of improving the response performance of a shutter curtain while reducing the drive electric power for the shutter curtain, and a camera.SOLUTION: A focal plane shutter for camera 1 comprises: a shutter curtain 150 configured to operate to open/close an opening 211 formed in a base plate 210; arms 141 and 142 which are rotatably supported by a shaft portion provided on the base plate 210 and connected to the shutter curtain 150; a drive gear 131 connected to the arms 141 and 142; and an actuator 120 for driving the shutter curtain 150 via the arms 141 and 142 and the drive gear 131. The actuator 120 includes: a yoke 122; a coil 121; a rotator 123; and an output gear 124 which is fixed to the rotator 123 so as to rotate on a rotation axis together with the rotator 123 and is engaged with the drive gear 131.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a focal plane shutter for a camera and a camera.

  A focal plane shutter for a camera generally includes a ground plate provided with an opening for irradiating light from a subject to a solid-state imaging device, and a blade group attached to the ground plate so that opening / closing of the opening can be changed. With curtains. The shutter curtain is driven, for example, using an actuator that rotates a rotor (rotor) by a magnetic force generated by a coil (see, for example, Patent Document 1).

  By the way, in recent cameras, there are demands such as an increase in the size of an image sensor and an increase in shutter speed. When a large image sensor is mounted, the opening of the base plate is usually increased according to the size of the image sensor, and the blades for opening and closing the image sensor are also enlarged, and the blades are heavy accordingly. Therefore, it may be necessary to increase the driving force for driving the blade by the actuator. In order to realize a high shutter speed, it is often desirable to increase the movement acceleration of the blades. Therefore, it may be necessary to increase the driving force for driving the blade by the actuator. As a method for increasing the driving force, it is conceivable to enlarge the rotor and the yoke constituting the actuator.

JP 2012-215658 A

  However, when the rotor and the yoke are increased, the detent torque generally increases, and as a result, the responsiveness of the shutter curtain may decrease, or the driving power required to drive the shutter curtain may increase. There is. Here, the detent torque is an attractive force that acts between the rotor and the yoke when no electromagnetic force is generated from the coil, that is, when the yoke is not excited.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a focal plane shutter for a camera and a camera capable of improving the response of the shutter curtain and reducing the driving power of the shutter curtain. .

In order to achieve the above object, a focal plane shutter for a camera according to the present invention comprises:
A shutter curtain that operates to open and close an opening provided in the base plate;
An arm that is rotatably supported by a shaft provided on the main plate and connected to the shutter curtain;
A drive gear coupled to the arm;
An actuator for operating the shutter curtain by the arm and the drive gear,
The actuator is
York,
A coil wound around the yoke;
A rotor that operates around the rotation axis to operate the shutter curtain by a magnetic force acting from the yoke when the coil is energized;
An output gear fixed to the rotor, rotatable around the rotation axis together with the rotor, and meshing with the drive gear;
The yoke is
A first sub yoke;
A second sub-yoke disposed at a distance from the first sub-yoke in the direction of the rotation axis of the rotor, and provided with a permanent magnet;
The permanent magnet is
The arrangement direction of the N pole and the S pole is arranged along one closed magnetic path that can be formed by the second sub yoke and the rotor.

The drive gear is
A main body provided with teeth that mesh with the output gear;
And an extension part extending from the main body part and connected to the arm.

  The yoke may be one that overlaps at least a part of the drive gear in the thickness direction of the base plate.

Further, the output gear has a plurality of first teeth arranged in an arc around the rotation axis,
The drive gear has a plurality of second teeth arranged in an arc around the rotation axis,
The plurality of first teeth may be meshed with the plurality of second teeth.

From another viewpoint, the camera according to the present invention is
The focal plane shutter for the camera,
A lens portion including one or more lenses;
A control unit that controls the operation of the focal plane shutter for the camera at the time of shooting;
A solid-state imaging device that converts light imaged through the lens unit into an electrical signal in accordance with the operation of the camera focal plane shutter.

  According to the present invention, the second sub yoke is provided with a permanent magnet. The magnetic force from the permanent magnet biases the rotor in the rotational direction at the time of photographing by appropriately setting the direction of the permanent magnet. Therefore, the initial movement of the rotor at the time of shooting can be made faster than when no permanent magnet is provided. Therefore, it becomes possible to improve the response of the shutter curtain.

  Further, since the rotor can be rotated using not only the electromagnetic force from the coil but also the magnetic force from the permanent magnet while the shutter curtain is operated at the time of shooting, it is more than the case where no permanent magnet is provided. The magnetic flux density of the yoke can be saturated with a small electric power. Accordingly, it is possible to reduce the driving power of the shutter curtain.

It is a perspective view of the camera concerning an embodiment. It is a disassembled perspective view of the focal plane shutter for cameras which concerns on embodiment. It is a front view of the focal plane shutter for cameras concerning an embodiment. It is a front view of a shutter curtain, an actuator, a drive gear, and an output gear concerning an embodiment. FIG. 5 is a cross-sectional view of the shutter curtain, the actuator, the drive gear, and the output gear according to the embodiment, taken along line AA in FIG. 4. It is a circuit diagram of a control device concerning an embodiment. It is operation | movement explanatory drawing of the actuator which concerns on embodiment. It is operation | movement explanatory drawing of the focal plane shutter for cameras which concerns on embodiment. It is operation | movement explanatory drawing of the actuator which concerns on embodiment. It is operation | movement explanatory drawing of the focal plane shutter for cameras which concerns on embodiment. It is operation | movement explanatory drawing of the actuator which concerns on embodiment. It is a top view of an actuator concerning a modification. It is a front view of the focal plane shutter for cameras concerning a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the camera 1000 according to the present embodiment includes a camera focal plane shutter 1, a control device 3, a solid-state imaging device 5, a housing 1001 that houses these, and one or a plurality of ones. A lens unit 1020 including a lens. The camera 1000 is a digital camera, a still camera, or the like. The housing 1001 is provided with operation buttons 1010 that are operated by the user at the time of shooting. The control device 3 is a device that controls the operation of the entire camera 1000, and includes a processor, a memory, and the like. For example, when the operation button 1010 is pressed during shooting, the control device 3 operates the camera focal plane shutter 1. The solid-state imaging device 5 is an element that converts light imaged through the lens unit 1020 into an electric signal, and is configured by, for example, a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary MOS) image sensor, or the like. In the present embodiment, the camera focal plane shutter 1 will be described as a single curtain type.

  As shown in FIG. 2, the camera focal plane shutter 1 is a so-called square shutter, and includes a base plate 210, a shutter curtain 150, arms 141 and 142, a drive gear 131, an actuator 120, and a holder 220.

  The base plate 210 has an opening 211 having a rectangular shape in plan view in a part thereof. As shown in FIG. 3, shaft portions 143 and 144 that rotatably support the arms 141 and 142 are provided on the outer peripheral portion of the opening 211 in the base plate 210. Further, the base plate 210 has a shaft portion 143 that rotatably supports a drive gear 131 described later.

  The shutter curtain 150 includes a plurality of blades. In the present embodiment, the shutter curtain 150 includes four blades 151, 152, 153, and 154. The shutter curtain 150 is connected to the arms 141 and 142, and moves up and down in plan view in conjunction with the arm 141 turning around the shaft portion 143 and the arm 142 turning around the shaft portion 144 at the time of shooting. Moving.

  Specifically, the shutter curtain 150 is in a state of covering a part of the opening 211 as the blades 151, 152, 153, and 154 move from the superimposed state. When the blades 151, 152, 153, 154 further move from this state, the shutter curtain 150 is unfolded and the opening 211 is fully closed.

  The superimposed state is a state in which a plurality of blades 151, 152, 153, and 154 overlap each other on the outer periphery of the opening 211 of the base plate 210 in plan view. In the superimposed state, the opening 211 is entirely open in plan view.

  The unfolded state is a state in which the plurality of blades 151, 152, 153, 154 are unfolded to cover the opening 211 of the ground plate 210 in plan view. In the unfolded state, the opening 211 is in a fully closed state in which everything is covered in plan view. FIG. 3 shows the shutter curtain 150 in the unfolded state.

  A shutter curtain 150 is connected to the arms 141 and 142. The arm 141 is rotatably supported by a shaft portion 143 provided on the main plate 210. The arm 142 is rotatably supported by a shaft portion 144 provided on the main plate 210. As shown in FIG. 3, the arm 141 is connected to the blade 151 through the pin 141a, is connected to the blade 152 through the pin 141b, is connected to the blade 153 through the pin 141c, and is connected to the blade 151 through the pin 141d. 154. The arm 142 is connected to the blade 151 through the pin 142a, connected to the blade 152 through the pin 142b, connected to the blade 153 through the pin 142c, and connected to the blade 154 through the pin 142d. Yes.

  As shown in FIG. 4, the actuator 120 includes a yoke 122, a coil 121 wound around a part of the yoke 122, and a rotor 123 that rotates around the rotation axis J <b> 2 to operate the shutter curtain 150. . The coil 121 is connected to the control device 3 through a conductive wire. The rotor 123 rotates by a magnetic force acting from the yoke 122 when the coil 121 is energized. The coil 121 is made of a conductive material such as copper. The rotor 123 is formed of a magnet magnetized so that the N pole and the S pole are aligned in a direction perpendicular to the rotation axis J2.

  As shown in FIGS. 2 and 5, the yoke 122 has a first sub yoke 122 a and a permanent magnet 122 d partially embedded therein, and is disposed away from the first sub yoke 122 a in the direction of the rotation axis J <b> 2 of the rotor 123. A second sub yoke 122b. The yoke 122 includes a shielding member 122c that is interposed between the first sub-yoke 122a and the second sub-yoke 122b and shields the electromagnetic field of the first sub-yoke 122a and the electromagnetic field of the second sub-yoke 122b from each other. Thereby, since the loss of the magnetic flux in the 1st sub yoke 122a can be reduced, the utilization efficiency of the electromagnetic force which generate | occur | produces in the coil 121 can be improved, and the electric power which should be supplied to the coil 121 can be reduced. .

  The first sub-yoke 122a has a long columnar shape with a substantially rectangular cross section, and two leg pieces 125a arranged in parallel with each other and a columnar shape with a substantially rectangular cross section, and connects one end of each of the two leg pieces 125a. And has a substantially C-shape as a whole. And the site | part of the one end side (-Z direction side of FIG. 5) in the rotating shaft J2 direction of the rotor 123 is located between the other end parts of the two leg pieces 125a. The first sub yoke 122a is made of a magnetic material.

  The second sub-yoke 122b also has substantially the same shape as the first sub-yoke 122a in plan view, and connects the two leg pieces 126a arranged in parallel to each other and one end of each of the two leg pieces 126a. And a piece 126b. And the site | part of the other end side (+ Z direction side of FIG. 5) in the rotating shaft J2 direction of the rotor 123 is located between the other end parts of the two leg pieces 126a. The second sub yoke 122b is made of a magnetic material. Further, as shown in FIG. 5, the thickness (first thickness) W1 of the first sub yoke 122a is set to be thicker than the thickness (second thickness) W2 of the second sub yoke 122b. That is, the cross sectional area of the first sub yoke 122a is set larger than the cross sectional area of the second sub yoke 122b. Here, if the magnetomotive forces of the magnetic circuits corresponding to the magnetic paths formed in the first sub yoke 122a and the second sub yoke 122b are the same, the magnetic flux density of the magnetic flux flowing through the first sub yoke 122a flows through the second sub yoke 122b. It becomes larger than the magnetic flux density of the magnetic flux. The ratio between the thicknesses W1 and W2 is that the force (detent torque) acting on the rotor 123 from the first sub yoke 122a is the force acting on the rotor 123 from the second sub yoke 122b when the coil 121 is not energized. It is set to be larger than that. As a result, the shutter curtain 150 can be maintained in the superimposed state while the detent torque acting on the rotor 123 is weakened while the coil 121 is not energized.

  The permanent magnet 122d is arranged so that the arrangement direction of the N pole and the S pole is along one closed magnetic path that can be formed by the second sub yoke 122b and the rotor 123. Here, the arrangement direction of the N pole and the S pole is, in other words, the magnetization direction of the permanent magnet 122d. This one closed magnetic path has a path that returns from the rotor 123 to the rotor 123 through one leg piece 126a of the two leg pieces 126a, the connecting piece 126b, and the other leg piece 126b. The permanent magnet 122d is embedded in the connecting piece 126b so that the alignment direction of the N pole and the S pole coincides with the direction from one of the two leg pieces 126a to the other (the + X direction in FIG. 4). The shielding member 122c is made of a nonmagnetic material such as a resin material. The shielding member 122c has substantially the same shape as the first sub yoke 122a and the second sub yoke 122b in plan view.

  The drive gear 131 is for driving the arm 141, is provided integrally with the arm 141, and the rotation axis J <b> 1 coincides with the central axis of the shaft portion 143. The drive gear 131 is fixed to the base end of the arm 141 opposite to the side connected to the shutter curtain 150. As shown in FIG. 2, the drive gear 131 has an insertion hole 131a through which the shaft portion 143 is inserted. When the drive gear 131 rotates on the rotation shaft J1, the arm 141 turns around the shaft portion 143 accordingly. .

  The output gear 124 is a gear for transmitting the torque generated by the actuator 120 to the drive gear 131. The output gear 124 according to the present embodiment is fixed to the rotor 123 by fitting, and thereby rotates in conjunction with the rotor 123. The output gear 124 has teeth provided in an arc shape, and these teeth mesh with the drive gear 131.

  According to such a configuration, when the rotor 123 rotates, the output gear 124 rotates about the rotation axis J <b> 2 of the rotor 123, and the output of the output gear 124 is transmitted to the drive gear 131. When the drive gear 131 rotates, the arm 141 fixed to the drive gear 131 turns the drive gear 131 around the rotation axis J1. Then, the shutter curtain 150 moves as the arm 141 turns. When the rotor 123 rotates counterclockwise, the state of the shutter curtain 150 shifts from the superimposed state to the deployed state. On the other hand, when the rotor 123 rotates clockwise, the state of the shutter curtain 150 shifts from the expanded state to the superimposed state.

  The holder 220 holds the actuator 120. The holder 220 is fixed to the base plate 210 with an adhesive or the like. The holder 220 is formed from a synthetic resin or the like. As shown in FIG. 2, the holder 220 includes a holder main body 220a and a lid portion 220b. The holder body 220a includes a shaft portion 223 that rotatably supports the rotor 123 of the actuator 120. A screw hole 220c is provided on the side of the holder main body 220a facing the lid 220b, and a through hole 220d is provided at a position corresponding to the screw hole 220c in the lid 220b. The lid 220b is fixed to the holder main body 220a by screwing a screw 221 inserted through the through hole 220d into the screw hole 220c.

  Next, the configuration of the control device 3 will be described. The control device 3 controls the state of the shutter curtain 150 by supplying a current to the coil 121. As shown in FIG. 6, the control device 3 includes a drive circuit 320 that drives the camera focal plane shutter 1, a control circuit 310 that controls the drive circuit 320, and a battery that supplies power to the drive circuit 320 and the control circuit 310. 300.

  The battery 300 is a power source that supplies a voltage within a range of, for example, a maximum of 3.2 V to a minimum of 2.2 V to the drive circuit 320 and the control circuit 310.

  The drive circuit 320 has a function of switching the direction of the current flowing through the coil 121, and is configured from a bridge-structured circuit including four transistors Tr11, Tr12, Tr13, Tr14. Here, when a current flows in the coil 121 from the left side to the right side in FIG. 6, the yoke 122 is excited so that the + Z direction side in FIGS. 3 and 4 is the N pole and the −Z direction side is the S pole. And Further, when a current flows through the coil 121 from the right side to the left side in FIG. 6, the yoke 122 is excited so that the −Z direction side in FIGS. 3 and 4 is the N pole and the + Z direction side is the S pole. To do.

  The control circuit 310 individually controls the transistors Tr11, Tr12, Tr13, and Tr14 included in the drive circuit 320. The control circuit 310 is connected to an input device (not shown) having an operation button 1010 provided on the camera 1000. When the operation button 1010 is pressed by the user, the input device outputs to the control circuit 310 a photographing instruction signal instructing to drive the blades 151, 152, 153, and 154 constituting the shutter curtain 150. The control circuit 310 moves the shutter curtain 150 from the superimposed state to the deployed state or from the deployed state to the superimposed state in response to the input of the shooting instruction signal.

  Next, the operation of the camera focal plane shutter 1 according to the present embodiment will be described. First, before photographing, a current is not supplied from the control circuit 310 to the coil 121 of the actuator 120 in a so-called non-energized state. In this state, in the first sub yoke 122a, as shown in FIG. 7A, the magnetic field represented by the magnetic field line MP11 that exits from the N pole of the rotor 123 and enters the S pole of the rotor 123 becomes dominant. Yes. In this case, a detent torque is applied from the first sub-yoke 122a to the rotor 123 in the clockwise direction as viewed from the + Z direction in FIG. 7A (see arrow AR11). On the other hand, in the second sub-yoke 122b, as shown in FIG. 7B, the permanent magnet 122d is arranged such that the arrangement direction of the N pole and the S pole (+ X direction in FIG. 4) coincides with the extending direction of the connecting piece 126b. Embedded in the connecting piece 126b. In the second sub yoke 122b, the magnetic field represented by the magnetic field line MP12 that exits from the N pole of the permanent magnet 122d and enters the S pole of the rotor 123 and exits from the N pole of the rotor 123 and enters the S pole of the permanent magnet 122d is dominant. It has become. As a result, a force is applied from the second sub-yoke 122b to the rotor 123 in a direction to rotate counterclockwise when viewed from the + Z direction in FIG. 7B (see arrow AR12).

  As described above, the thickness W1 of the first sub yoke 122a is set to be thicker than the thickness W2 of the second sub yoke 122b. Thus, the detent torque that acts on the rotor 123 from the first sub yoke 122a is larger than the force that acts on the rotor 123 from the second sub yoke 122b. Therefore, as shown in FIG. 8, a force is applied to the rotor 123 and the output gear 124 in the clockwise direction as viewed from the + Z direction (see arrow AR13), and the drive gear 131 is viewed from the + Z direction. A force in a direction to rotate counterclockwise acts (see arrow AR14). As a result, the shutter curtain 150 is maintained in a superimposed state.

  When the operation button 1010 is pressed during shooting, the control circuit 310 turns on the transistors Tr11 and Tr14 and turns off the transistors Tr12 and Tr13. As a result, current flows in the coil 121 from the left side to the right side in FIG. 6, and the yoke 122 is excited so that the + Y direction side in FIGS. 3 and 4 is the N pole and the −Y direction side is the S pole.

  In this state, in the first sub-yoke 122a, as shown in FIG. 9A, the magnetic field represented by the magnetic field line MP21 that exits from the N pole of the rotor 123, passes through the coil 121, and enters the S pole of the rotor 123. Become dominant. In this case, a force in a direction of rotating counterclockwise when viewed from the + Z direction is applied from the first sub yoke 122a to the rotor 123 (see arrow AR21). On the other hand, in the second sub yoke 122b, as shown in FIG. 9 (b), it exits from the N pole of the permanent magnet 122d, enters the S pole of the rotor 123 through the coil 121, and exits from the N pole of the rotor 123. The magnetic field represented by the magnetic field line MP22 entering the S pole of the permanent magnet 122d becomes dominant. As a result, a force is exerted on the rotor 123 from the second sub yoke 122b in a direction to rotate counterclockwise when viewed from the + Z direction (see arrow AR22).

  Thus, the force acting on the rotor 123 from the first sub yoke 122a and the force acting on the rotor 123 from the second sub yoke 122b are both in the direction in which the rotor 123 is rotated counterclockwise when viewed from the + Z direction. Works. Therefore, as shown in FIG. 10, the rotor 123 and the output gear 124 rotate counterclockwise when viewed from the + Z direction (see arrow AR23), and the drive gear 131 rotates clockwise when viewed from the + Z direction (arrow). AR24). Then, the shutter curtain 150 moves from the superimposed state to the deployed state (see arrow AR25).

  After a specific time has elapsed since the shutter curtain 150 is in the unfolded state, the control circuit 310 turns off the transistors Tr11 and Tr14 and turns on the transistors Tr12 and Tr13. As a result, a current flows through the coil 121 from the right side to the left side in FIG. 6, and the yoke 122 is excited so that the −Y direction side in FIGS. 3 and 4 is the N pole and the + Y direction side is the S pole.

  In this state, in the first sub yoke 122a, as shown in FIG. 11A, the magnetic field represented by the magnetic field line MP31 that exits from the N pole of the rotor 123, passes through the coil 121, and enters the S pole of the rotor 123. Become dominant. In this case, a force in a direction to rotate clockwise as viewed from the + Z direction acts on the rotor 123 from the first sub yoke 122a (see arrow AR31). On the other hand, in the second sub yoke 122b, as shown in FIG. 11 (b), it exits from the N pole of the permanent magnet 122d, enters the S pole of the rotor 123 through the coil 121, and exits from the N pole of the rotor 123. The magnetic field represented by the magnetic field line MP32 entering the south pole of the permanent magnet 122d becomes dominant. As a result, a force is applied from the second sub yoke 122b to the rotor 123 in a direction in which the second sub yoke 122b rotates counterclockwise as viewed from the + Z direction (see arrow AR32).

  At this time, the force acting on the rotor 123 from the first sub yoke 122a is larger than the force acting on the rotor 123 from the second sub yoke 122b. Therefore, contrary to the case shown in FIG. 9, the rotor 123 and the output gear 124 rotate clockwise, and the drive gear 131 rotates counterclockwise. Then, the shutter curtain 150 moves from the unfolded state to the superimposed state. The force acting on the rotor 123 from the second sub yoke 122b acts in a direction that inhibits the clockwise rotation of the rotor 123. Therefore, when the shutter curtain 150 moves from the deployed state to the superimposed state, the acceleration of the shutter curtain 150 is smaller than when the shutter curtain 150 moves from the superimposed state to the deployed state.

  As described above, according to the focal plane shutter 1 for a camera according to the present embodiment, the permanent magnet 122d is provided on the second sub yoke 122b. The magnetic force from the permanent magnet 122d biases the rotor 123 in the rotation direction (counterclockwise direction) at the time of photographing by appropriately setting the direction of the permanent magnet 122d. Therefore, since the rotor 123 can be urged in the rotation direction at the time of shooting before shooting, the initial movement of the rotor 123 at the time of shooting can be made faster than when the permanent magnet 122d is not provided. Therefore, it is possible to improve the response of the shutter curtain 150.

  Further, while the shutter curtain 150 is operated at the time of photographing, the rotor 123 can be rotated using not only the electromagnetic force from the coil 121 but also the magnetic force from the permanent magnet 122d, so that the permanent magnet 122d is provided. It is possible to saturate the magnetic flux density of the yoke 122 with a smaller electric power than in the case where it is not. Accordingly, it is possible to reduce the driving power of the shutter curtain 150.

  In addition, the permanent magnet 122d according to the present embodiment is arranged such that the arrangement direction of the N pole and the S pole is along one closed magnetic path that can be formed by the second sub yoke 122b and the rotor 123. Yes. Accordingly, when the shutter curtain 150 is shifted from the superimposed state to the deployed state, the force for rotating the rotor 123 counterclockwise when viewed from the + Z direction in FIG. 4 is increased. Therefore, the acceleration of the shutter curtain 150 can be increased.

(Modification)
Although the embodiment of the present invention has been described above, the present invention is not limited to the configuration of the above-described embodiment. For example, the permanent magnet 122d may be disposed so as to apply a force for rotating the rotor 123 clockwise from the second sub yoke 122b to the rotor 123. In this case, the permanent magnet 122d only needs to be embedded in the connecting piece 126b so that, for example, the arrangement direction of the N pole and the S pole coincides with the + X direction in FIG.

  The configuration of the yoke 122 according to the above-described embodiment having the shielding member 122c interposed between the first sub yoke 122a and the second sub yoke 122b has been described. However, the configuration is not limited to the configuration having the shielding member 122c. . For example, a configuration in which a gap is formed between the first sub yoke 122a and the second sub yoke 122b may be used. According to this configuration, since the shielding member 122c can be omitted, the number of parts of the yoke can be reduced, and the weight of the yoke can be reduced.

  In the actuator 120 according to the above-described embodiment, the example in which the permanent magnet 122d in the second sub yoke 122b is embedded in the connection piece 126b has been described. However, the position where the permanent magnet 122d is embedded is limited to the connection piece 126b. is not. For example, like the actuator 2120 shown in FIG. 12, the permanent magnet 2122d may be embedded in one leg piece 2126a of the second sub-yoke 2122b having two leg pieces 2126a and a connecting piece 2126b.

  In the embodiment described above, the thickness W1 of the first sub yoke 122a is set to be thicker than the thickness W2 of the second sub yoke 122b, so that the coil 121 can be rotated from the first sub yoke 122a without being energized. The configuration in which the force acting on the child 123 is larger than the force acting on the rotor 123 from the second sub yoke 122b has been described. However, the configuration in which the force acting on the rotor 123 from the first sub-yoke 122a is larger than the force acting on the rotor 123 from the second sub-yoke 122b when the coil 121 is not energized is used. It is not limited. For example, the gap between the first sub yoke 122a and the rotor 123 may be set to be smaller than the gap between the second sub yoke 122b and the rotor 123.

  In the above-described embodiment, the configuration in which no current is supplied from the control circuit 310 to the coil 121 of the actuator 120 in the state before photographing is described, but the present invention is not limited to this configuration. For example, in a state before photographing, the control circuit 310 may be configured to keep the transistors Tr11 and Tr14 off and the transistors Tr12 and Tr13 on. As a result, a current flows through the coil 121 from the right side to the left side in FIG. 6, and the yoke 122 is excited so that the −Y direction side in FIGS. 3 and 4 is the N pole and the + Y direction side is the S pole. In this state, a force in a direction to rotate clockwise as viewed from the + Z direction acts on the rotor 123 from the first sub yoke 122a (see arrow AR21). Since the force acting on the rotor 123 from the first sub yoke 122a is larger than the force acting on the rotor 123 from the second sub yoke 122b, the shutter curtain 150 is maintained in a superimposed state. .

  According to this configuration, it is not necessary to adjust the ratio between the thickness of the first sub yoke 122a and the thickness of the second sub yoke 122b, so that the actuator 120 can be easily manufactured.

  In the above-described embodiment, an example of a so-called single-curtain type camera focal plane shutter 1 including one shutter curtain 150 has been described, but the number of shutter curtains 150 is not limited to one. For example, the camera focal plane shutter may have a so-called two-curtain type configuration including two shutter curtains 150.

  As shown in FIG. 13, the camera focal plane shutter 3001 according to this modification includes two sets of the actuator 120, the drive gear 131, the output gear 124, the shutter curtain 150, and the like described in the first embodiment.

  In the focal plane shutter 3001 for the camera, for example, the shutter curtain 150 on the −Y direction side in FIG. 13 can be set as a so-called front curtain, and the shutter curtain 150 on the + Y direction side can be set as the rear curtain. In this case, the control circuit first executes the shutter driving process of the first embodiment for the shutter curtain 150 of the front curtain to change the shutter curtain 150 of the front curtain from the fully open state to the fully closed state, and then again to the fully open state. The drive circuit is controlled to After that, when a preset time elapses, the control circuit executes the shutter driving process of the first embodiment for the shutter curtain 150 of the rear curtain, so that the shutter curtain 150 of the rear curtain is changed from the fully open state to the fully closed state. Then, the drive circuit is controlled so as to be fully opened again. Since the solid-state imaging device is provided at a position where the light passing through the opening 3211 of the base plate 3210 is imaged, the shutter curtain 150 of the rear curtain is fully opened after the shutter curtain 150 of the front curtain is changed from the fully closed state to the fully opened state. Images can be captured during the time until the closed state.

  In the above-described embodiment, the example in which the shutter curtain 150 includes the four blades 151, 152, 153, and 154 has been described. However, the number of blades constituting the shutter curtain is not limited to four. For example, the number may be less than four or more than four.

  In the above-described embodiment, an example in which one shutter curtain 150 functions as a rear curtain has been described. However, for example, one shutter curtain 150 may be driven as a front curtain and then driven as a rear curtain. Good.

  In the digital camera according to the above-described embodiment, when the operation button 1010 is pressed while the shutter curtain 150 is fully opened (superimposed state), the shutter curtain 150 is fully closed (deployed state), and then the shutter is again opened. The example in which the curtain 150 is fully opened has been described. For example, the shutter curtain 150 may be fully opened when the shutter curtain 150 is fully closed and the operation button 1010 is pressed, and then the shutter curtain 150 may be fully closed again. In this case, the exposure time can be adjusted by adjusting the time during which the shutter curtain 150 is fully open.

1: focal plane shutter for camera, 3: control device, 5: solid-state imaging device, 120: actuator, 121: coil, 122: yoke, 122a: first sub yoke, 122b: second sub yoke, 122c: shielding member, 122d, 2122d: Permanent magnet, 123: Rotor, 124: Output gear, 131: Drive gear, 131a: Insertion hole, 141, 142: Arm, 141a, 141b, 141c, 141d, 142a, 142b, 142c, 142d: Pin, 143 144, 223: Shaft, 150: Shutter curtain, 151, 152, 153, 154: Blade, 210, 3210: Ground plate, 211, 3211: Opening, 220: Holder, 220a: Holder body, 220b: Lid, 221 : Screw, 300: Battery (power source), 310: Control circuit, 320: Drive Circuit, 1000: Camera, 1001: casing, 1010: operation buttons, 1020: lens unit, J1, J2: rotary shaft, Tr11, Tr12, Tr 13, Tr14: transistor

Claims (5)

A shutter curtain that operates to open and close an opening provided in the base plate;
An arm that is rotatably supported by a shaft provided on the main plate and connected to the shutter curtain;
A drive gear coupled to the arm;
An actuator for operating the shutter curtain by the arm and the drive gear,
The actuator is
York,
A coil wound around the yoke;
A rotor that operates around the rotation axis to operate the shutter curtain by a magnetic force acting from the yoke when the coil is energized;
An output gear fixed to the rotor, rotatable around the rotation axis together with the rotor, and meshing with the drive gear;
The yoke is
A first sub yoke;
A second sub-yoke disposed at a distance from the first sub-yoke in the direction of the rotation axis of the rotor, and provided with a permanent magnet;
The permanent magnet is
The arrangement direction of the N pole and the S pole is arranged along one closed magnetic path that can be formed by the second sub yoke and the rotor.
Focal plane shutter for camera. The drive gear is
A main body provided with teeth that mesh with the output gear;
An extension portion extending from the main body portion and coupled to the arm,
The focal plane shutter for a camera according to claim 1. The yoke overlaps at least a part of the drive gear in the thickness direction of the ground plane,
The focal plane shutter for a camera according to claim 1 or 2. The output gear has a plurality of first teeth arranged in an arc around the rotation axis,
The drive gear has a plurality of second teeth arranged in an arc around the rotation axis,
The plurality of first teeth mesh with the plurality of second teeth,
The focal plane shutter for a camera according to any one of claims 1 to 3. A focal plane shutter for a camera according to any one of claims 1 to 4,
A lens portion including one or more lenses;
A control unit that controls the operation of the focal plane shutter for the camera at the time of shooting;
A solid-state imaging device that converts light imaged through the lens unit into an electrical signal in accordance with the operation of the camera focal plane shutter;
camera.