JP6188331B2 - Light control device - Google Patents

Description

  The present invention relates to a light amount adjusting device such as a diaphragm device mounted on a lens barrel of an imaging device such as a digital camera.

  In some compact digital cameras, an ND filter is incorporated in an aperture device mounted on a lens barrel. This diaphragm device arbitrarily enters and retracts the ND filter to and from the diaphragm opening, and includes two drive sources: a motor that drives the diaphragm and an actuator that drives the ND filter.

  By allowing the ND filter to enter the aperture opening, it is possible to reduce the amount of light passing through the aperture opening without changing the aperture amount. Therefore, the amount of light can be reduced without reducing the aperture more than a predetermined value, and the diffraction phenomenon can be prevented.

  On the other hand, an aperture device mounted on a lens barrel of a digital single lens reflex camera that can shoot still images and moving images is required to be driven at a high speed in order to improve the continuous shooting speed in still image shooting. Smooth low-speed driving is required.

  The smooth low-speed driving mentioned here means that low-speed driving is performed with high resolution. If the aperture operation has a low resolution in moving image shooting, a discontinuous and unnatural light quantity change is acquired as a moving image and the quality is deteriorated, so that smooth low-speed driving is required.

  Further, when shooting a high-luminance subject, it is necessary to set the aperture to a small aperture state to increase the shutter speed, or to attach an ND filter to the tip of the lens barrel. However, if the aperture is too small, the resolution deteriorates due to the influence of diffraction. This deterioration in resolution is more pronounced in high-quality video modes such as full high-definition shooting.

  Also, if the shutter speed is made faster than a predetermined speed during moving image shooting, an uncomfortable image such as a rough frame-by-frame moving image may be generated, and this becomes more noticeable as the moving subject is shot. Furthermore, it is troublesome and time consuming for the photographer to attach the ND filter to the tip of the lens barrel every time depending on the luminance of the photographing subject.

  Conventionally, a diaphragm device mounted on a lens barrel of a digital single-lens reflex camera is driven by a single motor, so that high-speed driving and low-speed driving are performed within the range of the characteristics of the motor.

  For example, in a diaphragm device using a stepping motor as a drive source, high-speed driving performance for continuous shooting in still image shooting is ensured by 1-2 phase driving, and smooth low-speed driving in moving image shooting is achieved by microstep driving. (Patent Document 1).

JP-A-62-240942

  In Patent Document 1, since the diaphragm device is driven by one stepping motor, for example, if the magnetic flux density of the rotor magnet is increased so as to satisfy the high speed driving performance, the smooth low speed driving performance is impaired due to the increase of cogging torque. . For this reason, there is no choice but to balance the high speed driving performance and smooth low speed driving performance of the aperture device by driving one stepping motor, and both the improvement of the high speed driving performance of the aperture device and the improvement of the smooth low speed driving performance are compatible. It is difficult.

  In addition, the above-described diaphragm device incorporating the ND filter mounted on the lens barrel of the compact digital camera also includes two drive sources, but has only one drive source for driving the diaphragm. Problem arises.

  Therefore, the present invention can achieve both an improvement in high-speed driving performance during continuous shooting of still images and an improvement in smooth low-speed driving performance during movie shooting, and an amount of light that can be made less susceptible to diffraction. An object is to provide an adjusting device.

In order to achieve the above object, a light amount adjusting device of the present invention includes a plurality of light shielding members each having a first shaft portion and a second shaft portion and operable in a direction to open and close a photographing optical path; A first drive member in which the first shaft portions of the plurality of light shielding members are respectively fitted rotatably, a first motor that rotationally drives the first drive member, and the plurality of light shielding members A plurality of cam hole portions are formed in which the second shaft portions of the plurality of cam hole portions are slidably engaged, and one cam hole portion of the plurality of cam hole portions is formed by another cam hole portion. A second drive member provided with a portion in which an end of the first region is extended in the circumferential direction; a second motor that rotationally drives the second drive member; and the one cam hole portion It has a shaft part that is slidably fitted to the extended part, and can rotate so that it can move forward and backward with respect to the photographing optical path. And supported, by entering the photographing optical path, and a neutral density filter for dimming the quantity of light passing through the photographing optical path, said first region, the distance from the center of the second driving member It is a region that does not change in the circumferential direction, and the plurality of light shielding members rotate the first driving member by the first motor or rotate the second driving member by the second motor. When driven, it operates in a direction to open and close with respect to the photographing optical path, and the neutral density filter advances and retreats with respect to the photographing optical path by rotationally driving the second driving member by the second motor. Operatively enters the imaging optical path by rotation of the second driving member in the direction in which the plurality of light shielding members open, and from the imaging optical path by rotation in the direction in which the plurality of light shielding members of the second driving member closes. Evacuate, The resolution when opening and closing the plurality of light shielding members by driving the first motor is higher than the resolution when opening and closing the plurality of light shielding members by driving the second motor. .

  According to the light amount adjustment device of the present invention, it is possible to achieve both improvement in high-speed driving performance during continuous shooting of still images and improvement in smooth low-speed driving performance during moving image shooting, and make it less susceptible to diffraction. be able to.

It is a disassembled perspective view of the aperture stop apparatus which is an example of embodiment of the light quantity adjustment apparatus of this invention. It is sectional drawing in the assembly state of the diaphragm | throttle device shown in FIG. It is a figure which shows the initial state which retracted | retracted from both the aperture blade and the ND filter from the opening part of the 2nd drive member. (A) is a figure which shows the state which a diaphragm blade moved to the small aperture position with respect to the opening part of the 2nd drive member, and the ND filter retracted, (b) is with respect to the opening part of the 2nd drive member It is a figure which shows the state which the aperture blade retreats (aperture open | release) and the ND filter has approached. It is a figure which shows the state which the aperture blade moved to the small aperture position with respect to the opening part of the 2nd drive member, and the ND filter entered. (A) is a figure which shows the state which a diaphragm blade moved to the small aperture position with respect to the opening part of the 2nd drive member, and the ND filter retracted, (b) is with respect to the opening part of the 2nd drive member It is a figure which shows the state to which the aperture blade moved to the intermediate aperture position and the ND filter entered. It is a figure which shows the state which the aperture blade moved to the small aperture position with respect to the opening part of the 2nd drive member, and the ND filter entered.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view of a diaphragm device as an example of an embodiment of a light amount adjusting device of the present invention, and FIG. 2 is a cross-sectional view of the diaphragm device shown in FIG. 1 in an assembled state. In the present embodiment, an aperture device mounted on a lens barrel of a digital single-lens reflex camera is taken as an example.

  As shown in FIGS. 1 and 2, the diaphragm device of the present embodiment includes a first motor 1, a cover member 3, a second motor 2, a base member 4, a first drive member 5, and diaphragm blades 6 to 11. The second drive member 12 and the ND filter 13 are provided. Here, the diaphragm blades 6 to 11 correspond to an example of a light shielding member of the present invention, and the ND filter 13 corresponds to an example of a neutral density filter of the present invention.

  The first motor 1 is a stepping motor having m poles, and a pinion 1a is fixed to the tip of the output shaft. In the cover member 3, an opening 3a is formed at the center, and an arc-shaped cutout hole 3b is formed between the opening 3a and the outer periphery. The pinion 1a is inserted into the cutout hole 3b from the upper surface side of the cover member 3 in the figure, and the first motor 1 is fixed to the cover member 3 in this state.

  The second motor 2 is a stepping motor having n poles, and a pinion 2a is fixed to the tip of the output shaft. In the base member 4, an opening 4a is formed at the center, and an arc-shaped cutout hole 4d is formed between the opening 4a and the outer periphery.

  The pinion 2a is inserted into the cutout hole 4b from the lower surface side of the base member 4 in the figure, and the second motor 2 is fixed to the base member 4 in this state. Further, the base member 4 is provided with a shaft hole 4b in which the rotation shaft 13c of the ND filter 13 is rotatable, and an annular rib 4c in which the outer peripheral portion of the second drive member 12 is rotatably fitted. ing.

  The first drive member 5 is a member that opens and closes the aperture blades 6 to 11, and has an opening 5c at the center and a gear portion 5b at the outer periphery. Further, an annular protrusion 5a is provided around the opening 5c of the first drive member 5, and holes 5d to 5i are formed on the radially outer surface of the annular protrusion 5a.

  The annular protrusion 5a is rotatably fitted in the opening 3a of the cover member 3, and the first pinion 1a of the first motor 1 meshes with the teeth formed on the radially outer side of the gear part 5b. The drive member 5 is rotationally driven by the first motor 1.

  The diaphragm blades 6 to 11 are provided with first shaft portions 6a to 11a on one surface and second shaft portions 6b to 11b (partially not shown) on the other surface.

  The second drive member 12 is a member that opens and closes the diaphragm blades 6 to 11 with respect to the photographing optical path and moves the ND filter 13 forward and backward with respect to the photographing optical path. An opening 12a is formed at the center. A gear portion 12b is provided on the outer peripheral portion. The second drive member 12 is rotationally driven by the second motor 2 when the pinion 2a of the second motor 2 meshes with the teeth formed on the radially inner side of the gear portion 12b.

  The second drive member 12 is provided with cam holes 12c to 12h. The cam holes 12c to 12h include a first region where the distance from the center of the second drive member 12 does not change, and a second region that gradually approaches the center of the second drive member 12 from the first region. Are formed continuously (see FIG. 3).

  The second shaft portions 6b to 11b of the diaphragm blades 6 to 11 are slidably engaged with the cam holes 12c to 12h from the surface side (upper surface side in the drawing) of the second drive member 12. Further, the second shaft portion 13d of the ND filter 13 is slidably engaged with the cam hole portion 12f from the back surface side (the lower surface side in the drawing) of the second drive member 12.

  The ND filter 13 includes a filter portion 13a, an arm portion 13b, a first shaft portion 13c, and a second shaft portion 13d, and operates in a direction that moves forward and backward with respect to the imaging optical path.

  The cover member 3 is fixed to the base member 4 with the first driving member 5, the diaphragm blades 6 to 11, the second driving member 12, and the ND filter 13 sandwiched between the base member 4. At that time, the annular protrusion 5a of the first drive member 5 is fitted into the opening 3a of the cover member 3 and is rotatably supported.

  The diaphragm blades 6 to 11 are disposed between the first drive member 5 and the second drive member 12, and the first shaft portions 6 a to 11 a of the diaphragm blades 6 to 11 are arranged in the first drive member 5. The holes 5d to 5i are respectively fitted so as to be rotatable. The second shaft portions 6b to 11b are slidably fitted in the cam hole portions 12c to 12h of the second drive member 12, respectively.

  The ND filter 13 is disposed between the second drive member 12 and the base member 4, and the first shaft portion 13 c of the ND filter 13 is rotatably fitted in the shaft hole portion 4 b of the base member 4. The second shaft portion 13d is slidably fitted in the cam hole portion 12f of the second drive member 12. Further, the outer periphery of the second drive member 12 is rotatably fitted to the inner periphery of the annular rib of the base member 4.

  The opening 4a of the base member 4, the opening 5c of the first driving member 5, and the opening 12a of the second driving member 12 have substantially the same diameter, and any of these three members regulates the maximum opening. But it ’s okay. In the present embodiment, the opening 12a of the second driving member 12 will be described as a photographing optical path.

  Then, by rotating the first motor 1 counterclockwise in FIG. 1 and rotating the pinion 1a in the same direction, the first motor 1 is rotated through the gear portion 5b meshing with the pinion 1a. 1 is transmitted to one drive member 5. Thereby, the 1st drive member 5 rotates in the clockwise direction of FIG. At this time, the second motor 2 and the second drive member 12 are stopped.

  Further, since the first shaft members 6 a to 11 a of the aperture blades 6 to 11 are fitted in the holes 5 d to 5 i of the first drive member 5, the first drive member 5 rotates to change the first shaft portions 6 a to 11 a. The two shaft portions 6 b to 11 b move along the cam hole portions 12 c to 12 h of the second drive member 12. As a result, the aperture blades 6 to 11 rotate in the direction (close direction) to enter the imaging optical path with the first shaft portions 6a to 11a as fulcrums and are arranged at the aperture position. The aperture opening amount (aperture value) of the aperture blades 6 to 11 is controlled by the number of driving steps from the aperture stop state of the first motor 1.

  Similarly, by rotating the second motor 2 in the counterclockwise direction of FIG. 1 and rotating the pinion 2a in the same direction, the rotation of the second motor 2 is caused via the gear portion 12b meshing with the pinion 2a. It is transmitted to the second drive member 12. Thereby, the 2nd drive member 12 rotates in the clockwise direction of FIG. At this time, the first motor 1 and the first drive member 5 are stopped.

  Further, in the diaphragm blades 6 to 11, the second shaft portions 6 b to 11 b move along the cam hole portions 12 c to 12 h of the second drive member 12 by the rotation of the second drive member 12. As a result, the aperture blades 6 to 11 rotate in the direction (close direction) to enter the imaging optical path around the first shaft portions 6a to 11a and are arranged at the aperture position. The aperture opening amount (aperture value) of the aperture blades 6 to 11 is controlled by the number of driving steps from the aperture open state of the second motor 2.

  Here, when the number of poles of the first motor 1 is m and the number of poles of the second motor 2 is n, by setting m> n, the pinion 1a of the first motor 1 having a large number of poles is set. The number of steps required for one rotation is greater than that of the pinion 2a.

  For example, if the number of poles of the first motor 1 is set to 20 and the number of poles of the second motor 2 is set to 10, the number of steps required for one rotation of the pinion 1a of the first motor 1 during 2-2 phase driving. Is 40, and the number of steps required for one rotation of the pinion 2a of the second motor 2 is 20.

  When the reduction ratio between the pinion 1a and the gear portion 5b is P and the reduction ratio between the pinion 2a and the gear portion 12b is Q, and P = Q is set, the aperture blades 6 to 11 are opened to a small aperture state. The total number of steps when driving is larger in the first motor 1 having a larger number of poles.

  For example, when driving the aperture blades 6 to 11 from the open state to the small aperture state, if the first motor 1 requires three rotations, the second motor 2 also needs three rotations, and the number of drive steps of the first motor 1 Is 40 × 3 = 120, and the number of driving steps of the second motor 2 is 20 × 3 = 60.

  That is, the resolution when the diaphragm blades 6 to 11 are subjected to the diaphragm operation by driving the first motor 1 is higher than the resolution when the diaphragm blades 6 to 11 are subjected to the diaphragm operation by driving the second motor 2. . Therefore, driving the diaphragm blades 6 to 11 with the first motor 1 enables smoother driving. This is advantageous when the diaphragm blades 6 to 11 are driven at a low speed, and is suitable for moving image shooting.

  Further, when driving to the same aperture value, the number of drive steps is smaller when driven by the second motor 2 than when driven by the first motor 1. Therefore, when driving at the same driving frequency, driving with the second motor 2 enables faster driving, which is suitable for still image shooting for the purpose of improving the continuous shooting speed.

  In this embodiment, m> n and P = Q are set. However, the same effect as described above can be obtained even if m = n and P> Q. For example, if the number of poles m of the first motor 1 and the number of poles n of the second motor 2 are both set to 10 poles, the pinion 1a of the first motor 1 and the second motor 2 of the first motor 1 are driven during 2-2 phase driving. The number of steps required for one rotation of the pinion 2a is 20.

  Further, when the diaphragm blades 6 to 11 are driven from the open state to the small diaphragm state, the first motor 1 has a reduction ratio P of 30 (the number of teeth of the pinion 1a is 8, gear so that the small motor is in six rotations. The number of teeth of the part 5b is set to 240).

  Further, the reduction ratio Q is set to 15 (the number of teeth of the pinion 2a is 12 and the number of teeth of the gear portion 12b is 180) so that the second motor 2 is in the small-aperture state after three rotations. As a result, the number of driving steps of the first motor 1 is 20 × 6 = 120, and the number of driving steps of the second motor 2 is 20 × 3 = 60, and the same effect as described above can be obtained.

  Next, with reference to FIG. 3 to FIG. 7, an operation example of the aperture stop device of the present embodiment will be described. 3 to 7, illustrations other than the diaphragm blades 6 to 11, the second drive member 12, and the ND filter 13 and the gear portion 12 b of the second drive member 12 are omitted for convenience of explanation. ing.

  3 is a diagram illustrating an initial state of the aperture device, FIGS. 4 and 5 are diagrams for explaining an operation example of the aperture device in the still image shooting mode, and FIGS. 6 and 7 are operation examples of the aperture device in the moving image shooting mode. It is a figure for demonstrating.

  First, an initial state of the diaphragm device will be described with reference to FIG. In FIG. 3, all of the diaphragm blades 6 to 11 and the ND filter 13 are retracted from the photographing optical path. The second shaft portions 6 b to 11 b of the diaphragm blades 6 to 11 are located at the boundary between the first region and the second region of the cam hole portions 12 c to 12 h of the second drive member 12, and the ND filter 13. The second shaft portion 13 d is located at the end of the first region of the cam hole portion 12 f of the second drive member 12.

  Next, with reference to FIG. 4 and FIG. 5, an operation example of the diaphragm apparatus in the still image shooting mode will be described. FIG. 4A is a diagram illustrating a state in which the aperture blades 6 to 11 are moved to the small aperture position and the ND filter 13 is retracted with respect to the imaging optical path. When the second motor 2 is rotated forward from the state of FIG. 3 and the second drive member 12 is rotated in the clockwise direction in the figure, the cam holes 12c to 12h are moved to the clockwise direction as shown in FIG. Move around.

  At this time, in the diaphragm blades 6 to 11, the second shaft portions 6b to 11b move along the second regions of the cam hole portions 12c to 12h, and the hole portions 5d to 5d of the first drive member 5 in the stopped state. It rotates around the first shaft portions 6a to 11a fitted to 5i. As a result, the diaphragm blades 6 to 11 are rotated in the direction of entering the photographing optical path, and the small diaphragm state shown in FIG.

  FIG. 4B is a diagram illustrating a state in which the aperture blades 6 to 11 are retracted (open the aperture) and the ND filter 13 enters the imaging optical path. When the second motor 2 is rotated in the reverse direction from the state of FIG. 3 and the second drive member 12 is rotated in the counterclockwise direction in the figure, the cam holes 12c to 12h are moved in the counterclockwise direction.

  At this time, the ND filter 13 is fitted into the shaft hole 4b of the base member 4 by the second shaft 13d being pushed by the end of the first region of the cam hole 12f (the left end in the figure). It rotates counterclockwise around the first shaft portion 13c.

  Then, when the filter portion 13a of the ND filter 13 rotates to the center of the photographing optical path (optical axis center), the driving of the second motor 2 is stopped, and the state shown in FIG. When the filter portion 13a of the ND filter 13 is rotated to the center of the photographing optical path, the stopper portion provided on the second drive member 12 is brought into contact with the stopper portion provided on the base member 4, and at this point of contact. The driving of the second motor 2 may be stopped.

  At this time, since the second shaft portions 6b to 11b of the diaphragm blades 6 to 11 move only in the first regions of the cam hole portions 12c to 12h of the second drive member 12, the diaphragm blades 6 to 11 are The state retracted from the photographing optical path is maintained.

  Further, the cam hole portion 12f of the second drive member 12 has an end portion of the first region extended from the other cam hole portions 12c to 12e, 12g, and 12h, and the second shaft portion of the ND filter 13 is extended. 13 d does not interfere with the second shaft portion 9 b of the diaphragm blade 9.

  FIG. 5 is a diagram illustrating a state in which the aperture blades 6 to 11 have moved to the small aperture position and the ND filter 13 has entered the imaging optical path. From the state of FIG. 4B, the first motor 1 is rotated forward to rotate the first drive member 5 counterclockwise in the drawing. Here, since the first shaft members 6a to 11a of the aperture blades 6 to 11 are fitted in the holes 5d to 5i of the first drive member 5, the first drive member 5 is rotated counterclockwise. The first shaft portions 6a to 11a move in the same direction by the rotation in the direction.

  Thereby, after the 2nd axial parts 6b-11b of the aperture blades 6-11 move the 1st area | region of the cam hole parts 12c-12h of the 2nd drive member 12, they move along a 2nd area | region. Then, the aperture blades 6 to 11 are rotated in the direction of entering the photographing optical path to be in the small aperture state shown in FIG.

  As described above, in the still image shooting mode, when only the diaphragm blades 6 to 11 are subjected to the diaphragm operation, the second motor 2 may be driven to rotate forward. Further, when both the diaphragm blades 6 to 11 and the ND filter 13 enter the photographing optical path, the second motor 2 is driven to rotate backward to bring the ND filter 13 into the in-coming state, and then the first motor 1 is moved forward. The diaphragm blades 6 to 11 are squeezed to rotate.

  Next, an example of the operation of the aperture device in the moving image shooting mode will be described with reference to FIGS. FIG. 6A is a diagram illustrating a state in which the aperture blades 6 to 11 are moved to the small aperture position and the ND filter 13 is retracted with respect to the imaging optical path.

  When the first motor 1 is rotated forward from the state of FIG. 3 and the first drive member 5 is rotated counterclockwise in the figure, the first drive member 5 is fitted into the holes 5d to 5i. The first shaft portions 6a to 11a of the diaphragm blades 6 to 11 move in the same direction.

  As a result, the second shaft portions 6b to 11b of the diaphragm blades 6 to 11 move along the second regions of the cam hole portions 12c to 12h of the second drive member 12, and the diaphragm blades 6 to 11 enter the photographing optical path. The small aperture state shown in FIG.

  Here, in FIG. 5, the driving amount of the first motor 1 when the diaphragm blades 6 to 11 are moved to the small aperture state with the ND filter 13 entering the imaging optical path is denoted by A. In FIG. 6A, if the driving amount of the first motor 1 when the diaphragm blades 6 to 11 are moved to the small aperture state with the ND filter 13 retracted from the photographing optical path is B, A is B More (A> B).

  FIG. 6B is a diagram illustrating a state in which the diaphragm blades 6 to 11 have moved to the intermediate diaphragm position and the ND filter 13 has entered the imaging optical path.

  When the second motor 2 is reversely rotated from the state of FIG. 6A to rotate the second drive member 12 counterclockwise in the figure, the cam hole portions 12c to 12h of the second drive member 12 are formed. Move in the same direction.

  At this time, the ND filter 13 includes a first shaft portion 13c in which the second shaft portion 13d is pushed by the end portion of the first region of the cam hole portion 12f and is fitted into the shaft hole portion 4b of the base member 4. Rotate counterclockwise around the center.

  The driving of the second motor 2 is stopped when the filter portion 13a of the ND filter 13 rotates to the center of the imaging optical path (optical axis center). When the filter portion 13a of the ND filter 13 is rotated to the center of the photographing optical path, the stopper portion provided on the second drive member 12 is brought into contact with the stopper portion provided on the base member 4, and at this point of contact. The driving of the second motor 2 may be stopped.

  At this time, since the second shaft portions 6b to 11b of the diaphragm blades 6 to 11 move to the middle of the second region of the cam hole portions 12c to 12h of the second drive member 12, the diaphragm blades 6 to 11 are Move in the opening direction. That is, as shown in FIG. 6B, when the filter portion 13a of the ND filter 13 is rotated to the center of the photographing optical path, the aperture blades 6 to 11 are in the intermediate aperture state.

  In this way, the amount by which the passage light amount increases by opening the diaphragm blades 6 to 11 to the intermediate diaphragm position and the amount by which the passage light amount decreases by the ND filter 13 entering the center of the photographing optical path are made the same. Thus, it is possible to prevent a change in the amount of passing light when the ND filter 13 enters.

  For example, the rotation angle of the second drive member 12 for causing the ND filter 13 to enter the imaging optical path is set to an angle at which the aperture F value is changed from F22 to F11 and the light quantity is quadrupled. What is necessary is just to make it the light reduction amount of the filter 13 become 1/4.

  FIG. 7 is a diagram illustrating a state in which the aperture blades 6 to 11 have moved to the small aperture position and the ND filter 13 has entered the imaging optical path.

  When the first motor 1 is rotated forward again from the state of FIG. 6B and the first driving member 5 is rotated counterclockwise in the drawing, the holes 5d to 5i of the first driving member 5 are formed. The first shaft portions 6a to 11a of the fitted diaphragm blades 6 to 11 move in the same direction. Thereby, the 2nd axial parts 6b-11b move to the aperture blades 6-11 along the cam hole parts 12c-12h of the 2nd drive member 12, and become a small aperture state shown in FIG.

  As described above, in the moving image shooting mode, when only the aperture blades 6 to 11 are operated for the aperture operation, the first motor 1 may be driven to rotate forward. Further, when both the diaphragm blades 6 to 11 and the ND filter 13 are allowed to enter the photographing optical path, the first motor 1 is driven to rotate in the forward direction to cause the diaphragm blades 6 to 11 to perform the diaphragm operation (intermediate diaphragm). The second motor 2 is rotated in the reverse direction to bring the ND filter 13 into the entering state. Thereafter, in order to further reduce the amount of light, the first motor 1 is driven to rotate in the forward direction again and the diaphragm blades 6 to 11 are subjected to the diaphragm operation (small diaphragm).

  For example, in the moving image shooting mode, when the amount of light is exceeded even if the aperture blades 6 to 11 are moved to a small aperture position where the influence of diffraction does not occur (FIG. 6A) during shooting, the ND filter 13 is moved to the shooting optical path. After entering (FIG. 6B), the diaphragm blades 6 to 11 may be squeezed (FIG. 7). At this time, since there is no change in the amount of passing light when the ND filter 13 enters, it is possible to perform exposure control that does not give an uncomfortable feeling that the brightness changes suddenly during photographing.

  As described above, in the present embodiment, in the aperture operation using only the aperture blades 6 to 11, the still image shooting mode is driven by the second motor 2 that is deficient in resolution but can be driven at high speed, and in the movie shooting mode. The first motor 1 is driven with a high resolution and smooth low-speed driving. In this way, by using both shooting modes properly, it is possible to achieve both high-speed driving and smooth low-speed driving in shooting still images and moving images.

  Further, in the present embodiment, when the diaphragm blades 6 to 11 and the ND filter 13 are operated, in the still image shooting mode, the second motor 2 is driven to rotate backward to bring the ND filter 13 into the ingress state, and then the second The first motor 1 is driven to rotate in the forward direction, and the diaphragm blades 6 to 11 are subjected to the diaphragm operation. In the moving image shooting mode, the first motor 1 is driven to rotate in the forward direction to stop the diaphragm blades 6 to 11, and then the second motor 2 is driven to rotate in the reverse direction to bring the ND filter 13 into the entering state. Furthermore, when it is desired to narrow down the diaphragm blades 6 to 11, the first motor 1 is driven to rotate forward again to cause the diaphragm blades 6 to 11 to perform a diaphragm operation.

  Accordingly, when it is desired to set the ND filter 13 in the small aperture state, it is possible to set it more quickly during still image shooting. In addition, it is possible to automatically enter the ND filter 13 during still image shooting and moving image shooting without providing a dedicated motor for operating only the ND filter 13. For this reason, since it is possible to take measures against high luminance without further reducing the aperture diameter, it is difficult to be affected by diffraction.

  In the present embodiment, in moving image shooting using the ND filter 13, the diaphragm blades 6 to 11 are driven in the opening direction in conjunction with the entry of the ND filter 13, so that there is no change in the amount of passing light. This enables exposure control that does not give a sense of incongruity such that the brightness changes suddenly during shooting.

  The configuration of the present invention is not limited to that exemplified in the above embodiment, and the material, shape, dimensions, form, number, arrangement location, and the like can be changed as appropriate without departing from the scope of the present invention. It is.

DESCRIPTION OF SYMBOLS 1 1st motor 2 2nd motor 3 Cover member 4 Base member 5 1st drive members 6-11 Diaphragm blade 12 2nd drive member 13 ND filter

Claims (5)

A plurality of light shielding members each having a first shaft portion and a second shaft portion and operable in a direction to open and close the photographing optical path;
A first drive member in which the first shaft portions of the plurality of light shielding members are respectively fitted so as to be rotatable;
A first motor that rotationally drives the first drive member;
A plurality of cam hole portions that are slidably engaged with the second shaft portions of the plurality of light shielding members are formed, and one cam hole portion of the plurality of cam hole portions is provided with another cam hole portion. A second drive member provided with a portion in which the end of the first region is extended in the circumferential direction from the cam hole;
A second motor that rotationally drives the second drive member;
A shaft portion that is slidably fitted in the extended portion of the one cam hole portion is supported so as to be able to move forward and backward with respect to the photographing optical path, and enters the photographing optical path. And a neutral density filter for reducing the amount of light passing through the photographing optical path,
The first region is a region where the distance from the center of the second drive member does not change in the circumferential direction,
The plurality of light shielding members are configured to rotate the first driving member by the first motor, or to rotate the second driving member by the second motor, so that Work in the direction to open and close
The attenuating filter moves forward and backward with respect to the imaging optical path by rotating the second drive member by the second motor, and the plurality of light shielding members of the second drive member are opened. Entering the imaging optical path by rotation of the second drive member, retracting from the imaging optical path by rotation of the plurality of light shielding members of the second drive member,
The resolution when opening and closing the plurality of light shielding members by driving the first motor is higher than the resolution when opening and closing the plurality of light shielding members by driving the second motor. Light quantity adjustment device.   In the still image shooting mode, the second motor is driven to bring the neutral density filter into the shooting optical path, and then the first motor is driven to close the plurality of light shielding members from the open state. In the moving image shooting mode, the plurality of light-shielding members are moved from the open state to the close direction by driving the first motor, and the second motor is driven in this state. 2. The light amount adjusting device according to claim 1, wherein a neutral density filter is caused to enter the photographing optical path, and the plurality of light shielding members are in an intermediate aperture state in which an aperture opening is covered with the neutral density filter.   In the still image shooting mode, the driving amount of the first motor when operating the plurality of light blocking members from the open state to the small aperture state with the neutral density filter entering the photographing optical path is the neutral density filter. 3. The light amount according to claim 1, wherein the amount of light is larger than a driving amount of the first motor when the plurality of light shielding members are operated from an open state to a small aperture state in a state of being retracted from the photographing optical path. Adjusting device.   The number of poles of the first motor is m, the number of poles of the second motor is n, the reduction ratio when the first driving member is rotationally driven by the first motor is P, the second motor 2. When the reduction ratio when the second drive member is rotationally driven by a motor is Q, m> n and P = Q, or m = n and P> Q. The light quantity adjusting device according to any one of claims 1 to 3.   5. The light amount adjusting device according to claim 1, wherein the light shielding member is a diaphragm blade, and the neutral density filter is an ND filter.

Images