JP5368697B2 - Light control device, lens device, camera system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for improving a diaphragm aperture error without changing the basic constitution of a diaphragm device. <P>SOLUTION: The light quantity adjusting device has a plurality of diaphragm blades arranged to overlap one another, a stepping motor for driving the diaphragm blades, and a cam member abutting on the diaphragm blades and guiding them. The plurality of diaphragm blades are operated along the cam member by the stepping motor to adjust the opening of the diaphragm aperture. A frictional force applying means is provided for increasing sliding frictional force from the open side of the diaphragm aperture in the mutual sliding contact part of the diaphragm blades to the vicinity of an intermediate diaphragm. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a light amount adjusting device mounted on, for example, a lens barrel of a camera.

  As a conventional light amount adjusting device, there is an electromagnetic driving device having a stepping motor of a 1-2 phase driving method in which a plurality of aperture blades are step-driven to change the aperture opening degree. If this device stops at a position where the cogging torque is unstable when the power is cut off, the aperture stops the rotor at a stable position where the diaphragm blades are shifted by one step from the small aperture side to the open side. An error occurs. Further, since the direction of deviation cannot be specified, if the positive direction is the small aperture side and the negative direction is the open side, an aperture error of ± 1 step occurs (for example, Patent Document 1).

Moreover, in order to improve the said subject, there exists a technique which restricts the direction shifted for one step forcibly to one direction (positive direction or negative direction) to one direction, and improves aperture accuracy (for example, patent) Reference 2).
JP-A-1-164258 JP-A-5-249538

  In Patent Document 1, when shooting is performed with the exposure corrected in stages (shifted) by an auto exposure bracketing (hereinafter referred to as AEB) function or the like, the exposure does not change or is overcorrected with respect to the exposure correction command. As a result, a result contrary to the photographer's intention may occur. Further, in Patent Document 2, since the driving is forcibly performed for one step, the aperture diameter error for at least one step must be allowed.

  In either case, by always energizing, it can be held at the desired stop position without causing a one-step aperture error. However, after driving to the desired stop position for power saving, drive It is desirable to cut off the energization for the purpose.

  This invention is made in view of the said subject, and implement | achieves the technique which can improve the aperture error by the cogging torque after electricity supply interruption | blocking, without changing the basic composition of a diaphragm | throttle device.

In order to solve the above-described problems, a light amount adjusting device of the present invention abuts on a plurality of diaphragm blades that are arranged so as to overlap each other to form a diaphragm aperture, a stepping motor that drives the diaphragm blades, and the diaphragm blades. and a cam member for guiding Te, wherein a light amount adjustment device of the diaphragm blades of by the stepping motor Rifuku number is actuated along said cam member to regulate an opening degree of the throttle opening, the throttle The blades overlap each other when the aperture opening is in an open state, the leading end of the aperture blade contacts another adjacent aperture blade, and the aperture when the aperture opening is in a small aperture state. be those not in contact with the other diaphragm blade adjacent is pushed up is the tip of the blade, the cogging torque acting on the rotor when energization of the said stepping motor It exceeds manner, to form a high friction coefficient unit having a higher coefficient of friction than the other surface of the diaphragm blades in the distal portion of the diaphragm blade.

Further, the light amount adjusting device of the present invention guides a plurality of diaphragm blades that are arranged so as to overlap each other to form a diaphragm aperture, a stepping motor that drives the diaphragm blades, and a shaft portion of the diaphragm blade. and a cam member which cam holes are formed, said a light amount adjusting device for adjusting an opening degree of the plurality of diaphragm blades is operated along the cam hole the diaphragm opening by a stepping motor, the stepping The coefficient of friction of the side surface of the cam hole with which the shaft portion of the aperture blade abuts when the aperture opening is in an open state so as to exceed the cogging torque acting on the rotor when energization to the motor is interrupted , When the aperture opening is in the small aperture state, the friction coefficient is set higher than the friction coefficient of the side surface of the cam hole with which the shaft portion of the aperture blade abuts .

  According to the present invention, it is possible to improve the aperture error due to the cogging torque after energization interruption without changing the basic configuration of the expansion device.

  Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings.

  The embodiment described below is an example for realizing the present invention, and should be appropriately modified or changed according to the configuration and various conditions of the apparatus to which the present invention is applied. It is not limited to the embodiment.

[Camera system]
First, a camera system equipped with a lens device to which the light amount adjusting device of the present invention is applied will be described.

  FIG. 6 is a block diagram showing a camera system to which a lens device to which the light amount adjusting device of the present invention is applied is mounted.

  In FIG. 6, reference numeral 200 denotes a camera body, and 300 denotes an interchangeable lens body that is detachably attached to the camera body 200. The interchangeable lens body 300 is attached to the camera body 200 to constitute an interchangeable lens autofocus (AF) single-lens reflex camera. doing.

  The camera body 200 includes a power switch 203, a release switch 204, and a camera CPU 201. The lens body 300 includes a lens CPU 301, a focusing device 306, and a diaphragm device 307.

  The camera CPU 201 is composed of a microcomputer and controls the distance measuring device 208, the photometric device 205, the exposure device 206, the storage device 207, the display device 209, and the like. The camera CPU 201 communicates with the lens CPU 301 when the lens contact 302 and the camera contact 202 are connected when the lens body 300 is mounted.

  The power switch 203 can be operated from the outside, and the camera CPU 201 is activated by turning on the power switch 203 so that power can be supplied to each actuator and sensor in the system and the system can be operated.

  The release switch 204 is a two-stroke switch that can be operated from the outside, and its operation signal is input to the camera CPU 201. If the first stroke SW of the release switch 204 is ON, the camera CPU 201 drives the focusing lens to the focusing device 306 based on the determination of the exposure amount by the photometry device 205 and the distance measurement calculation result of the subject by the distance measurement device 208. Performs in-focus operation and in-focus determination by command. Thereby, the photographing preparation state is entered.

  When the camera CPU 201 detects that the second stroke SW of the release switch 204 has been operated to ON, the camera CPU 201 transmits a drive command for the diaphragm device 307 to the lens CPU 301 in the lens body 300. Then, the aperture device 307 is driven, and an exposure start command is transmitted to the exposure device 206 to perform an actual exposure operation. When an exposure end signal is received, a recording start command is transmitted to the storage device 207 to store a captured image. Execute the process.

  The display device 209 displays various shooting conditions such as an aperture value and shutter speed, the number of shots, the remaining battery level, and various modes according to commands from the camera CPU 201.

  The lens CPU 301 controls operations of various device circuits such as a focusing device 306 and a diaphragm device 307 built in the lens body 300 as a control unit. The lens CPU 301 communicates with the camera CPU 201 when the lens body 300 is attached to the camera body 200 and the lens contact 302 and the camera contact 202 are connected.

  The focusing device 306 includes an in-focus lens and a lens holding member as an optical system, a focusing lens driving unit for driving the focusing lens to a target position, and a driving force of the focusing lens driving unit. And a transmission mechanism for transmitting as a moving force. The focusing device 306 includes a focusing lens driving circuit that is controlled by the lens CPU 301 according to the movement amount information of the focusing lens transmitted from the camera CPU 201 and sends a driving command to the focusing lens driving unit.

  The aperture device 307 has a plurality of aperture blades that are arranged on the circumference so as to overlap each other and form an aperture opening, and has an aperture mechanism that sets the aperture (area) of the aperture opening. The aperture device 307 includes a drive unit for driving the aperture mechanism and a drive circuit that is controlled by the lens CPU 301 in accordance with the aperture operation command transmitted from the camera CPU 201 and sends a drive command to the drive unit.

[Light control device]
FIG. 1 is an exploded perspective view of a diaphragm device according to an embodiment to which the light amount adjusting device of the present invention is applied. FIG. 2 is a perspective view of the drive unit of FIG. 3 and 4 are side views for explaining a method of assembling the diaphragm mechanism and the drive unit of FIG. FIG. 5 is a partial cross-sectional view of FIG.

  1 and 2, the light amount adjusting device of the present embodiment includes a cover member 1, a rotor 2, bobbins 5a and 5b, a yoke 9, a bearing member 10, a position detector 12, a case member 13, a rotary plate 14, and a diaphragm blade. 15 and a cam plate 16. Here, the cover unit 1, the rotor 2, the bobbins 5a and 5b, the yoke 9, the bearing member 10 and the like constitute a drive unit. The position detector 12, the case member 13, the rotary plate 14, the diaphragm blade 15, the cam plate 16, and the like constitute an aperture mechanism.

  The cover member 1 is made of an elastic material such as synthetic resin, and houses the rotor 2 and the bobbins 5a and 5b. A bearing hole 1a is formed in a substantially central portion of the cover member 1, and holes 1b-1 to 1b-4 through which the terminals of the bobbins 5a and 5b are inserted are formed around the bearing hole 1a. Further, on both sides of the cover member 1, there are provided protruding pieces 1 c for pressing the position detector 12 and seats 1 d for pressing and fixing the cover member 1 to the case member 13.

  The projecting piece 1 c is provided with holes 1 c-1 to 1 c-3 through which the terminal portion 12 a of the position detector 12 is inserted, and a protrusion 1 j (pressing portion: see FIG. 2) that contacts the end surface of the position detector 12. It has been. The seat 1d is provided with fastening member insertion holes 1d-1 and fitting pieces 1e-1 and 1e-2 for positioning in the case member 13 by fitting. Also, a thin piece portion (thin portion) 1f is provided near the bearing hole 1a of the seat portion 1d.

  Further, the cover member 1 is provided with an elastic piece 1k having a locking claw portion (locking portion) 1k-2 for snap-fit coupling to the case member 13 at the tip. Further, the cover member 1 is provided with fitting portions 1g-1, 1g-2, 1h-1 to 1h-4, and 1i-1 to 1i-4 for fitting and positioning the yoke 9. .

  The rotor 2 is composed of a permanent magnet, and a disk-shaped core 3 is fixed to the inner peripheral portion by adhesion or the like. A rotating shaft 4 is fitted and fixed to the core 3 by press fitting or the like, and an end portion of the rotating shaft 4 on the cover member 1 side is rotatably supported in a bearing hole 1a of the cover member. Further, a washer 7 is interposed between the core 3 and the bearing member 10 to reduce sliding friction between the end surface of the core 3 and the end surface of the bearing member 10. The washer 7 is made of a material having high lubricity.

  The bobbins 5a and 5b are made of synthetic resin or the like and have a terminal portion for supplying power. In addition, coils 6a and 6b are attached to the bobbins 5a and 5b, and coil lead wires are wound around the terminal portions and subjected to plating with solder. Further, an insulating sheet member 8 is interposed between the coils 6a and 6b and the yoke 9 so as to prevent both from conducting. The seat member 8 is formed with a relief hole portion 8a of the bearing member 10 and relief hole portions 8b-1 and 8b-2 of the yoke 9.

  The yoke 9 is made of a soft magnetic material, and stator portions 9b-1 and 9b-2 bent so as to face the rotor 2 in the radial direction, and a hole portion 9a for fixing the bearing member 10 by press-fitting or the like. And it has fitting surface portions 9c-1 to 9c-6 for fitting with the cover member 1.

  The bearing member (bearing portion) 10 is made of a magnetic material, and has a bearing hole 10a that rotatably supports an end portion of the rotating shaft 4 on the opposite side of the cover member 1 and a flange portion 10b. A pinion 11 is fixed to the tip of the rotating shaft 4 protruding from the bearing hole 10a. The pinion 11 has a hole portion 11a for fixing the rotary shaft 4 by press fitting or the like, and a gear portion 11b for transmitting the rotational force of the drive unit to the rotary plate 14.

  The position detector 12 uses a position detection element such as a photo interrupter and detects the rotational position of the rotary plate 14. The position detector 12 is provided with a terminal portion 12a.

  The case member 13 is made of synthetic resin or the like and has a protruding portion 13a protruding in the optical axis direction. The case member 13 has a receiving surface portion 13a-3 with which the back surface of the seat portion 1d of the cover member 1 abuts, and fitting end surfaces 1e-1-a, 1e-2-a of the fitting piece portions 1e-1, 1e-2. Is provided with a fitting protrusion 13a-2-a. The fitting protrusion 13a-2 is also provided on the back surface.

  Further, the case member 13 is fitted with a screw hole portion 13a-1 for fastening the fastening member 17 inserted into the fastening member insertion hole 1d-1, an insertion hole portion 13b of the pinion 10, and a flange portion 10b of the bearing member 10. A hole 13c and a seating surface 13d for contacting the end surface of the yoke 9 are provided.

  Further, the case member 13 is provided with a housing part 13e for housing the position detector 12, a relief hole 13g for the shielding plate part 14a of the rotary plate 14, and an insertion hole 13f for the elastic piece part 1k. Further, the case member 13 has insertion grooves 13h-1 to 13h-3 of the snap fit portions 16b-1 to 16b-3 of the cam plate 16, fitting holes of the positioning shafts 16a-1 and 16a-2, and a groove 13i-. 1,13i-2 is applied. Furthermore, the case member 13 is provided with a fitting hole 13j into which the fitting ribs 14b-1 to 14b-6 of the rotary plate 14 are fitted.

  The rotary plate (drive member) 14 is made of synthetic resin or the like, and is provided with a shielding plate portion 14a as a detection piece for shielding the projection light of the position detector 12. Further, the rotary plate 14 is provided with fitting rib portions 14b-1 to 14b-6 for fitting in the fitting hole portion 13j and rotating the rotary plate 14 about the optical axis.

  Further, the rotary plate 14 is provided with a gear portion 14 c that meshes with the gear portion 11 b of the pinion 11 and transmits a rotational driving force to the rotary plate 14. Furthermore, the rotary plate 14 is fitted with a fitting hole 14d for fitting the fitting shafts 15a-1, 15b-1, 15c-1, 15d-1, 15e-1, 15f-1 of the diaphragm blade 15. -1 to 14d-6 are provided.

  Further, the rotary plate 14 has projections 14e-1 to 14e-3 (14e-3 not shown) for contacting the end surface of the case member 13 in the optical axis direction to determine the position of the rotary plate 14 in the optical axis direction. ) Is provided. The protrusions 14e-1 to 14e-3 are arranged approximately equally around the optical axis. An opening 14 f is provided at the center of the rotary plate 14.

  The aperture blade 15 is made of synthetic resin or a thin metal plate, and is fitted with fitting shaft portions 15a-1, 15b-1, 15c-1, 15d-1, which are fitted into the fitting hole portions 14d-1 to 14d-6. 15e-1 and 15f-1. Further, the diaphragm blade 15 has shaft portions 15a-2, 15b-2, 15c-2, 15d-2, 15e-2, 15f-2 (15b-2) that engage with the cam holes 16c to 16h of the cam plate 16. 15c-2 and 15d-2 are not shown).

  The cam plate (cam member) 16 includes cam holes 16 c to 16 h and shaft portions 16 a-1 and 16 a-2 for positioning with the case member 13. Further, the cam plate 16 is provided with snap fit portions 16b-1 to 16b-3 and an opening hole portion 16k for snap fitting the cam plate 16 to the case member 13.

[Assembly procedure of drive unit]
Next, the assembly procedure of the drive unit will be described with reference to FIGS.

  First, the outer diameter portion of the bearing member 10 is fixed to the hole 9 a of the yoke 9 by press fitting or the like, and the bearing member 10 is attached to the yoke 9. In this state, the flange portion 10b of the bearing member 10 contacts the end surface of the yoke 9, and the bearing member 10 is positioned with respect to the yoke 9. Further, the hole portions 8 b-1 and 8 b-2 of the sheet member 8 are inserted into the stator portions 9 b-1 and 9 b-2 of the yoke 9, and the sheet member 8 is laid on the yoke 9.

  Next, the hollow holes (not shown) of the bobbins 5a and 5b to which the coils 6a and 6b are attached are inserted into the stator portions 9b-1 and 9b-2 of the yoke 9. Next, the washer 7 is inserted through the rotating shaft 4 of the rotor unit in which the rotor 3 and the rotating shaft 4 are integrated, and the tip of the rotating shaft 4 is fitted into the hole 10 a of the bearing member 10.

  Next, the yoke 9 is attached to the cover member 1. At the time of such attachment, the fitting surface portions 9c-1-a to 9c-4-a and 9c-5 and 9c-6 of the yoke 9 are fitted to the fitting portions 1h-1 to 1h-4, 1g-1, 1g-. 2 respectively. As a result, the state shown in FIG. 2 is obtained. Here, when the fitting surface portion and a part of the fitting portion, for example, the fitting surface portions 9c-5 and 9c-6 and the fitting portions 1g-1 and 1g-2 are set to be press-fitted, the yoke 9 is attached to the cover member 1. It is fixed, and there is no need to inadvertently disassemble and reassemble during assembly. And the assembly of a drive unit is completed by fixing the pinion 11 to the front-end | tip part of the rotating shaft 4 by press injection.

  Next, a procedure for attaching the cover member 1 of the drive unit to the case member 13 of the aperture mechanism will be described with reference to FIGS.

  First, as shown in FIG. 3, the cover member 1 of the drive unit is moved to the case member 13 of the diaphragm mechanism from the optical axis direction. At that time, the position detector 12 is housed in the housing portion 13 e of the case member 13. Next, the cover member 1 is further moved closer to the case member 13, and the fitting end faces 1e-1-a and 1e-2-a are fitted to the fitting protrusions 13a-2-a and 13a-2-b ( (Not shown). Further, the outer diameter of the flange portion 10 b of the bearing member 10 is fitted into the hole portion 13 c of the case member 13.

  By these fittings, the cover member 1 is positioned on the case member 13, and the terminal portions 12a are inserted into the holes 1c-1 to 1c-3 simultaneously with the fitting. When the cover member 1 is further moved closer to the case member 13, the end surface of the seat portion 1d comes into contact with the receiving surface portion 13a-3. The receiving surface portion 13a-3 is an inclined surface, and as shown in FIGS. 1 and 3, a height difference α is provided in a line direction connecting the center of the hole portion 13a-1 and the center of the hole portion 13c. The hole 13c side is lower.

  Next, when the cover member 1 is tightened into the case member 13 by the fastening member 17, the thin piece portion 1f is elastically deformed so that the end surface of the seat portion 1d follows the receiving surface portion 13a-3 having a height difference. Since the height difference α is lower on the hole 13c side than the hole 13a-1, the elastic deformation generates a force with which the end surface 9e of the yoke 9 abuts against the seat surface 13d. In this state, the positions of the yoke 9 and the case member 13 in the optical axis direction are determined, and the position of the pinion 11 is arranged at an appropriate position.

  Thereby, good meshing between the gear portion 11b of the pinion 11 and the gear portion 14c of the rotary plate 14 is maintained, and an accurate opening diameter by the aperture blade 15 is obtained. The protrusion 1d-2 provided on the seat 1d receives the end surface of the seat 1d by the end surface of the fastening member 17 pressing the protrusion 1d-2 when the fastening member 17 is tightened. It is intended to actively follow the surface portion 13a-3 and is provided closer to the thin piece portion 1f.

  On the other hand, in the state where the cover member 1 is attached to the case member 13, as shown in FIG. 5, the slanted portion 1 k-1 of the locking claw portion 1 k-2 of the elastic piece 1 k and the locking applied to the case member 13. The nail | claw part 13k contacts. At this time, since the position of the inclined surface portion 1k-1 is set so that the elastic piece portion 1k has a slight amount of deflection, referring to FIG. 3, the contact force of the end surface 9e of the yoke 9 to the seat surface 13d The cover member 1 is held by the case member 13 while having (biasing force).

  Furthermore, in this state, as shown in FIG. 5, the protrusion 1j of the cover member 1 abuts on the end surface 12b of the position detector 12, and the protruding piece 1c presses the position detector 12 with a slight amount of deflection. keeping.

  Here, as shown in FIGS. 4 and 5, P is the approximate center position of the thin piece 1 f of the cover member 1 that is elastically deformed, Q is the position where the end surface 9 e of the yoke 9 is in contact with the seat surface 13 d, and the elastic piece Let R be the position where the slope 1k-1 of the 1k locking projection 1k-2 contacts the locking claw 13k. Further, S is a position where the projection 1j of the protruding piece 1c contacts the end surface 12b of the position detector 12.

  Further, the vertical component force f1a of the force f1 that the yoke member 9 presses the seating surface 13d at the point Q with respect to the line segment PQ is f1a, the vertical component force with respect to the line segment PR of the force f2 that the cover member 1 receives at the point R is f2a, and the cover. A vertical component force of the force f3 received by the member 1 at the point S with respect to the line segment PS is defined as f3a.

  When the length of the line segment PQ is L1, the length of the line segment PR is L2, and the length of the line segment PS is L3, the relationship f1a · L1 + f2a · L2> f3a · L3 is satisfied.

  By satisfying at least the above-mentioned relationship, the cover member 1 is lifted from the case member 13 against the force received by the projection 1j of the projecting piece 1c (the contact force of the end surface 9e against the seat surface 13d is not obtained). Can be avoided. Therefore, good meshing between the gear portion 11b of the pinion 11 and the gear portion 14c of the rotary plate 14 is maintained, and an accurate opening diameter by the aperture blade 15 is obtained.

  As described above, in this embodiment, the position detector 12 can be accurately positioned and fixed with respect to the shielding plate portion 14 a of the rotary plate 14 by the urging force of the cover member 1. Thereby, the fluctuation | variation of the detection timing by the position shift of the position detector 12 can be avoided.

  Further, the cover member 1 is configured to hold the case member 13 in the optical axis direction so that the drive unit is incorporated in the optical axis direction without rotating. Thereby, it is not necessary to provide a flange portion for fixing the drive unit, and space saving can be realized.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  For example, in the above embodiment, the case where the elastic piece 1k is provided on the cover member 1 is illustrated. However, if the relationship of f1a · L1> f3a · L3 is satisfied, the elastic piece 1k may be omitted. Good.

  Further, the receiving surface portion 13a-3 of the case member 13 is not necessarily an inclined surface. For example, the receiving surface portion 13a-3 provided with the protruding portion and the end surface of the seat portion 1d abut against each other with a pressing force to elastically deform the thin piece portion 1f and attach the end surface 9e of the yoke 9 to the seat surface 13d. You may make it contact | abut with power. Moreover, you may provide the said projection part in the seat part 1d side instead of the receiving surface part 13a-3 side.

  Further, the contact between the end surface 9e of the yoke 9 and the seat surface 13d of the case member 13 may be contact by a plurality of protrusions. Further, when the cover member 1 and the yoke 9 are set to be press-fitted, the yoke 9 is fixed to the cover member 1, so that the contact portion with the seating surface 13 d is not the end surface 9 e of the yoke 9 but one of the cover members 1. It is good also as a part.

  Now, when the light quantity adjusting device having the above configuration is driven by the stepping motor of the 1-2 phase driving system, the torque characteristics as schematically shown in FIGS. 7 and 8 are obtained.

  FIG. 7 shows the torque characteristics at a certain rotor stop position during one-phase energization, FIG. 8 shows the torque characteristics at a certain rotor stop position during two-phase energization, the horizontal axis represents the rotor rotation angle, and the vertical axis represents The torque is a characteristic for a half circumference (180 °) when a certain rotor position is set as a reference (0 °). Reference numeral 101 denotes torque (coil generation torque) generated in the rotor when the coil is energized, and reference numeral 102 denotes cogging torque. The positive direction in the figure is the small aperture direction (or the open direction), and the negative direction is the open direction (or the small aperture direction). 103 is the sliding friction torque in the positive direction (torque mainly due to the sliding friction force between the adjacent diaphragm blades), 104 is the sliding friction torque in the negative direction (torque mainly due to the sliding friction force between the adjacent diaphragm blades) ). However, the positive and negative directions of the sliding friction torque are opposite to the coil generation torque and the cogging torque for convenience. The small aperture is a state in which the aperture value is controlled to be the maximum (the aperture aperture diameter is minimum), and the open aperture is controlled to have the aperture value being the minimum (diaphragm aperture diameter is maximum). It is in the state.

  The black circles 105 and 108 are magnetically stable positions of the coil generation torque. A position indicated by a black dot 106 is a magnetically stable position of the cogging torque.

  First, paying attention to FIG. 7 during one-phase driving, the magnetically stable positions of the coil generation torque and the cogging torque coincide at a position where the rotor rotation angle is 75 °. If the power supply to the coil is cut off in this state, only the cogging torque is obtained, but the rotor is maintained at that position because it stops at the magnetically stable position of the cogging torque.

  On the other hand, when attention is paid to FIG. 8 during two-phase energization, the position of the rotor rotation angle of 90 ° is a magnetically stable position of the coil generation torque, but at that position, the cogging torque is a magnetically unstable position. Therefore, when the power supply to the coil is cut off in this state, the rotor moves to the position of the rotor rotation angle of 75 ° or 105 ° by the cogging torque and stops at the magnetically stable position of the cogging torque. However, this is a case where the sliding friction torque is not taken into consideration, and when there is a sufficient sliding friction torque, the rotational movement of the rotor can be stopped by overcoming the torque to be moved to the magnetically stable position of the cogging torque. On the other hand, when the sliding friction torque is extremely small, the cogging torque is superior to the sliding friction torque due to the vibration of the rotor at the time of stopping, and the rotor rotates and moves to a magnetically stable position.

  FIG. 9 shows changes in the sliding friction torque from the open position to the small stop. Reference numeral 111 denotes a conventional sliding friction torque, and reference numeral 112 denotes a time when the diaphragm blade starts to rise when the diaphragm blade operates toward the small diaphragm side. The close-up is a phenomenon in which when a plurality of aperture blades are overlapped on the circumference to form an aperture opening, the aperture protrudes in the optical axis direction as the entire aperture blade is operated to a small aperture. That is, since the adjacent diaphragm blades are displaced in the optical axis direction, the edges of the adjacent diaphragm blades push up the diaphragm blade between the vicinity of the intermediate diaphragm and the small diaphragm side, and the entire diaphragm blade operates to the small diaphragm The opening protrudes in the direction of the optical axis as it goes. Reference numeral 113 denotes a limit sliding friction torque that does not move to the magnetically stable position when the cogging torque is stopped at the magnetically unstable position and the current is cut off. The intermediate diaphragm is a diaphragm state that is intermediate between the small diaphragm and the full aperture.

  Now, looking at the change of the sliding friction torque in FIG. 9, the sliding friction torque 111 is relatively low in the vicinity of the open to middle diaphragm, and is stopped at the magnetically unstable position of the cogging torque to cut off the energization. Sometimes it moves to a magnetically stable position. On the other hand, if it starts to increase further by narrowing down, the sliding friction torque will increase rapidly, and even if it stops at the magnetically unstable position of the cogging torque and cuts off the current, it will not move to the magnetically stable position. . However, it is not necessary that the sliding friction torque be large, and coil generation torque that can overcome it is necessary. Increasing the sliding torque in the dark clouds is not preferable because it leads to an increase in device size and power consumption. .

  Therefore, in this example, the frictional force applying means described below is used to increase the sliding friction torque from the open side to the vicinity of the middle diaphragm, and the small diaphragm side is configured not to increase the sliding friction torque without increasing the coil generation torque. The aperture diameter accuracy is improved.

  FIG. 10 shows an open state of the diaphragm blades of the light amount adjusting device to which the present invention is applied. Reference numeral 121 in the figure shows a cross-sectional view of one of the plurality of diaphragm blades. The tip portion where the diaphragm blades are in sliding contact with each other has a surface with a higher friction coefficient than the other surfaces (hereinafter referred to as a high friction coefficient portion). ) 121a is formed. The high friction coefficient portion 121a is formed on all the diaphragm blades. In the state of the intermediate aperture from the open side, the high friction coefficient portion 121a is always in contact with the surface 122a of the adjacent aperture blade 122, so that a sliding frictional force is obtained.

  On the other hand, FIG. 11 shows a small aperture state of the aperture blade of the light amount adjusting device to which the present invention is applied. In this state, as described above, the diaphragm blade 121 in which the edge portions 122a and 123a of the adjacent diaphragm blades 122 and 123 are disposed is pushed up. Due to this mechanism, the diaphragm blades ascend in the optical axis direction as a whole. Further, in this state, the surface 121a at the tip of the diaphragm blade 121 leaves the adjacent diaphragm blade surface 122a due to the uplift, so that no sliding friction force is generated by the high friction coefficient portion 121a.

  With the above configuration, the sliding friction torque is as indicated by 114 in FIG. That is, the sliding friction torque increases only in the vicinity of the open to middle aperture and exceeds the sliding friction torque 113 of the movement limit, and does not increase in the vicinity of the small aperture. Therefore, it is not necessary to increase the coil generation torque by increasing the size of the drive unit or increasing the power consumption, and stable aperture diameter accuracy can be obtained from open to small apertures.

  In FIGS. 10 and 11, a surface having a higher coefficient of friction than the other surfaces is formed at the tip of the diaphragm blade. However, as shown in FIGS. The same effect can be obtained even in a configuration in which is pressed.

  FIG. 12 shows an open state of the diaphragm blades of the light amount adjusting device to which the present invention is applied. At the tip of the diaphragm blade 131, a bent portion 131a and a contact surface portion 131b that contacts the end surface of the adjacent diaphragm blade 132 are provided. In the state from the open state to the intermediate stop, the contact surface portion 131b is in contact with the end face of the adjacent stop blade 132. Further, in this state, since the diaphragm blades are slightly bent, the contact surface portion 131b is in contact with the end surfaces of the adjacent diaphragm blades 132 while pressing. Thereby, a sliding frictional force can be obtained from the open position to the intermediate aperture.

  On the other hand, FIG. 13 shows a small aperture state of the aperture blade of the light amount adjusting device to which the present invention is applied. In this state, as described above, the leading end of the diaphragm blades is lifted by the uplift phenomenon, so that the contact surface portion 131b leaves the end surface of the adjacent diaphragm blade 132 and does not increase the sliding frictional force.

  With the above configuration, the sliding friction torque is as indicated by 114 in FIG. That is, the sliding friction torque increases only in the vicinity of the open to middle aperture and exceeds the sliding friction torque 113 of the movement limit, and does not increase in the vicinity of the small aperture. Therefore, even in this configuration, it is not necessary to increase the coil generation torque by increasing the size of the drive unit or increasing the power consumption, and a stable aperture diameter accuracy from open to small aperture can be obtained. In the above configuration, the diaphragm blade tip is bent, but the same effect can be obtained even if the entire surface of each diaphragm blade is formed into a curved surface.

  By the way, in each of the above-mentioned configurations, the sliding frictional force is generated by the diaphragm blades. The structure which generate | occur | produces dynamic friction force may be sufficient. That is, in a configuration in which the cam hole (16c to 16h in FIG. 1) side surface and the shaft portion (15a-2 to 15f-2 in FIG. 1) of the aperture plate engage with each other, the friction coefficient on the cam side surface is reduced to the small aperture side. By forming so that the open side is higher than the above, the same effect as described above can be obtained.

  Further, the shaft portion is configured to be elastically deformed when a force (side pressure) is applied in a direction orthogonal to the axial direction of the shaft portion, and the width dimension of the cam hole is made slightly smaller than the shaft portion diameter. Then, the sliding friction force acting on the shaft portion is changed by gradually changing the opening side and the small aperture side (for example, the width dimension on the open side <the width size on the small aperture side) to change the side pressure to the shaft portion. The effect similar to the above can be obtained by changing between the wide open and the small aperture.

It is a disassembled perspective view of the light quantity adjustment apparatus of embodiment which concerns on this invention. It is a perspective view of the drive unit of the light quantity adjustment apparatus shown in FIG. It is a figure explaining the assembly method of the aperture mechanism and drive unit of the light quantity adjusting device shown in FIG. FIG. 2 is an assembly diagram of a diaphragm mechanism and a drive unit of the light amount adjusting device shown in FIG. FIG. 5 is a partial cross-sectional view of FIG. 4. It is a block diagram which shows the camera system with which the lens apparatus to which the light quantity adjustment apparatus of this invention was applied was mounted | worn. It is a figure which shows the sliding friction torque of the light quantity adjustment apparatus to which this invention is applied. It is a figure which shows the sliding friction torque of the light quantity adjustment apparatus to which this invention is applied. It is a figure which shows the change of the sliding friction torque of this invention and the conventional light quantity adjustment apparatus. It is a figure which shows the open state of the aperture blade of the light quantity adjustment apparatus to which this invention is applied. It is a figure which shows the small aperture state of the aperture blade of the light quantity adjustment apparatus to which this invention is applied. It is a figure which shows the open state of the aperture blade of the light quantity adjustment apparatus to which this invention is applied. It is a figure which shows the small aperture state of the aperture blade of the light quantity adjustment apparatus to which this invention is applied.

Explanation of symbols

1 Cover member 1d-2 Thin piece (thin part)
1j Protruding part (pressing part)
1k Elastic piece 1k-2 Locking claw part (Locking part)
2 Rotor 3 Core 4 Rotating shaft 6 Coil 7 Washer 8 Sheet member 9 Yoke 10 Bearing member (bearing portion)
11 Pinion 12 Position detector 13 Case member 14 Rotary plate (drive member)
15 Diaphragm blade 16 Cam plate (cam member)

Claims (4)

Includes a plurality of diaphragm blades for forming the aperture stop is disposed so as to overlap each other, a stepping motor for driving the diaphragm blades, and a cam member which abuts the guide with the diaphragm blades, Ri by said stepping motor a light amount adjusting device for adjusting an opening degree of the throttle opening of the diaphragm blades of the multiple is actuated along said cam member,
When the aperture opening is in an open state, the aperture blades are overlapped with each other so that the front end of the aperture blade contacts another adjacent aperture blade, and the aperture opening is in a small aperture state. The tip of the diaphragm blade is pushed up and does not come into contact with other adjacent diaphragm blades,
A high coefficient of friction portion having a higher coefficient of friction than the other surface of the diaphragm blade is formed at the tip of the diaphragm blade so as to exceed the cogging torque acting on the rotor when the energization to the stepping motor is cut off. A light amount adjusting device characterized by that. A plurality of aperture blades that are arranged so as to overlap each other and that form an aperture opening, a stepping motor that drives the aperture blades , and a cam member that is formed with a cam hole that contacts and guides the shaft portion of the aperture blades A light amount adjusting device that adjusts the opening of the aperture opening by operating the plurality of aperture blades along the cam hole by the stepping motor;
The friction coefficient of the side surface of the cam hole with which the shaft portion of the aperture blade abuts when the aperture opening is opened so that the cogging torque acting on the rotor when the energization to the stepping motor is interrupted is exceeded. The light quantity adjusting device is characterized in that the coefficient of friction is set to be higher than the friction coefficient of the side surface of the cam hole with which the shaft portion of the diaphragm blade abuts when the aperture opening is in a small aperture state . A light amount adjustment equipment according to claim 1 or 2,
An optical system having a plurality of lenses;
A lens device comprising: a control unit that controls the light amount adjusting device and the optical system. A lens device according to claim 3 ;
A camera system comprising: a camera device to which the lens device is detachable.

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