JP2015079199A - Amount-of-light adjustment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time required for transition to a minimum aperture state from a full-aperture state in amount-of-light adjustment devices.SOLUTION: An amount-of-light adjustment device according to the present invention comprises: a stationary frame member that has an opening serving as a through-hole where an optical axis passes through; an annular rotation drive member that is rotatable around the optical axis relatively to the stationary frame member; a plurality of cum grooves that are formed in the rotation drive member; a plurality of blade members that, in a periphery of the optical axis, is provided in the stationary frame member, is rotatably disposed around a shaft parallel to the optical axis, and has driven pins engaging with the cum grooves provided, respectively; and a stepping motor that rotatably drives the rotation drive member. An aperture diameter of the opening formed by respective edges of the plurality of blade members can be changed, and a shape of the cum groove is determined so that a relation between a rotation angle of the rotation drive member and the amount of change in an AV value increases a tilt as the rotation angle increases in a direction where the AV value is larger.

Description

  The present invention relates to a light amount adjusting device that adjusts the amount of light passing through an opening by changing the aperture diameter using a plurality of blade members.

  Some lens devices provided in an imaging apparatus such as a still camera or a video camera include a light amount adjusting device called a so-called diaphragm device on an optical path through which a light beam passes in order to perform light amount adjustment.

  As a light amount adjusting device, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2011-107584, a plurality of blade members arranged around the optical axis are rotated around an axis parallel to the optical axis to open an opening. The structure which changes the aperture of is known.

  In the light amount adjusting device disclosed in Japanese Patent Application Laid-Open No. 2011-107584, the rotation angle of the stepping motor that generates power for driving the blade member and the change in the aperture value are in a non-linear relationship. A change amount of the aperture value with respect to the rotation angle becomes small.

JP 2011-107584 A

  In an imaging apparatus that captures still images, it may be required to increase the number of continuous shots per second. For this reason, in the light quantity adjusting device, it is desired to reduce the time required from the open state to the minimum aperture state.

  The present invention has been made in view of the above-described points, and an object of the present invention is to shorten the time required for transition from the open state to the minimum aperture state in the light amount adjusting device.

  A light amount adjusting device according to an aspect of the present invention includes a fixed frame member having an opening that is a through hole through which an optical axis passes, and an annular rotational drive that can rotate around the optical axis relative to the fixed frame member A member, a plurality of cam grooves formed in the rotation drive member, and around the optical axis, arranged rotatably around an axis parallel to the optical axis provided in the fixed frame member, An opening formed by each edge portion of the plurality of blade members; and a plurality of blade members provided with driven pins that engage with the cam grooves; and a stepping motor that rotationally drives the rotation driving member. The light amount adjusting device is capable of changing the aperture of the rotation drive member so that the relationship between the rotation angle of the rotation drive member and the amount of change in the AV value increases as the rotation angle increases in the direction in which the AV value increases. The shape of the cam groove is It is fit.

  According to the present invention, it is possible to shorten the time required for transition from the open state to the minimum aperture state in the light amount adjusting device.

It is a perspective view of a light quantity adjustment device. It is a disassembled perspective view of a light quantity adjustment apparatus. It is the figure seen from the arrow [3] direction of FIG. 1, Comprising: It is a front view of a light quantity adjustment apparatus. It is the elements on larger scale which expand and show the area | region shown by code | symbol [4] of FIG. It is a top view of a blade member. It is a side view of a blade member. It is a perspective view of a torsion spring. It is the figure which showed only the blade | wing member and the rotational drive member in the open state. It is the figure which showed only the blade member and the rotational drive member in the minimum aperture state. It is the elements on larger scale which show the relationship between a blade member and a rotation drive member in the viewpoint fixed with respect to the rotation drive member. It is a graph which shows the relationship between the rotation angle of a rotation drive member, and the variation | change_quantity of an aperture value.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings used for the following description, the scale of each component is made different in order to make each component recognizable on the drawing. It is not limited only to the quantity of the component described in (1), the shape of the component, the ratio of the size of the component, and the relative positional relationship of each component.

  First, a schematic configuration of a light amount adjusting apparatus according to an embodiment of the present invention will be described below. FIG. 1 is a perspective view showing an appearance of a light amount adjusting apparatus according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the light amount adjusting device of FIG. FIG. 3 is a front view of the light amount adjusting device as viewed from the direction of the arrow [3] in FIG. FIG. 4 is a partially enlarged view showing a part of FIG. 3 (area indicated by reference numeral [4]) in an enlarged manner.

  As shown in FIGS. 1 to 3, etc., the light amount adjustment device 10 of the present embodiment includes a fixed frame member 11, a rotation drive member 12, a plurality of blade members 13, a lid member 14, a torsion spring 15, It is mainly composed of a stepping motor 16, an urging spring 18, a position sensor 20 and the like.

  The light amount adjusting device 10 constitutes a so-called diaphragm mechanism provided in a lens device of an imaging device such as a still camera or a video camera. The light amount adjusting device 10 has an opening 10a through which the optical axis L in the lens device passes. The light amount adjusting device 10 includes a plurality of blade members 13 that are rotatable around an axis parallel to the optical axis L disposed around the opening 10a, and advances and retracts the plurality of blade members 13 into the opening 10a. Thus, the aperture through which the light beam along the optical axis L can pass is changed.

  Among the constituent members of the light amount adjusting device 10, the fixed frame member 11 is a basic constituent member in the light amount adjusting device 10. The fixed frame member 11 is formed in a substantially annular shape as a whole, and has a substantially circular opening 11a at a substantially central portion thereof.

  Specifically, the fixed frame member 11 is formed by an annular flat surface portion 11p, an outer peripheral wall surface 11m, and an inner peripheral wall surface 11n. Here, the outer peripheral wall surface 11m is a wall-shaped portion formed so as to surround the outer peripheral edge portion of the annular flat surface portion 11p. The inner peripheral wall surface 11n is a wall-shaped portion formed so as to surround the inner peripheral edge portion of the annular flat surface portion 11p. With this configuration, the fixed frame member 11 forms an annular housing having an internal space formed by the annular flat surface portion 11p, the outer peripheral wall surface 11m, and the inner peripheral wall surface 11n. A rotation drive member 12 and a plurality of blade members 13 are accommodated in the internal space of the fixed frame member 11 (details will be described later). Moreover, the site | part which opposes the annular plane part 11p of the fixed frame member 11 is opening, and the cover member 14 is arrange | positioned so that this opening site | part may be covered. As described above, the fixed frame member 11 and the lid member 14 form a casing portion of the light amount adjusting device 10.

  A plurality of stepping motors 16 (in this example) are provided on one side surface of the annular flat surface portion 11p of the fixed frame member 11 on the outer surface side opposite to the side where the internal space portion is formed. Two) screws 17 are fixed. For this purpose, a plurality (two in this example) of screw holes 11d are formed in the vicinity of the attachment part of the stepping motor 16 in the annular plane part 11p.

  The stepping motor 16 is an electric actuator for rotating the rotation drive member 12 by a predetermined amount in a predetermined rotation direction at a predetermined timing. In the present application, as an example, the stepping motor 16 has a rotating drive shaft. The drive shaft of the stepping motor 16 is disposed so as to penetrate through a through hole 11f formed in a predetermined portion of the annular flat surface portion 11p of the fixed frame member 11. A pinion gear 16 a is fixed to the tip end side of the drive shaft of the stepping motor 16. The pinion gear 16 a meshes with the sector gear 12 d of the rotation drive member 12. With this configuration, the rotational driving force of the stepping motor 16 is transmitted to the rotational driving member 12 via the driving shaft, the pinion gear 16a, and the sector gear 12d. In response to this rotational driving force, the rotational driving member 12 is configured to be rotationally driven by a predetermined amount in a predetermined direction.

  The rotation driving member 12 is a blade driving member provided for receiving the driving force of the stepping motor 16 to drive the plurality of blade members 13. The entire rotation drive member 12 is formed in a substantially annular shape having a slightly smaller diameter than the fixed frame member 11, and has a substantially circular opening 12a at a substantially central portion thereof. The rotation drive member 12 is disposed so as to be rotatable with respect to the fixed frame member 11 in the internal space of the fixed frame member 11.

  A sector gear 12d is formed at a portion of the outer peripheral edge of the rotational drive member 12. As described above, the pinion gear 16a of the stepping motor 16 is engaged with the sector gear 12d.

  Further, a coil spring locking portion A12b that locks one end of the urging spring 18 is formed at one portion in the vicinity of the outer peripheral edge portion of the rotation driving member 12. The coil spring locking portion A12b is an on-axis portion formed so as to protrude in a direction substantially orthogonal to the radial direction of the rotation drive member 12. The tip of the coil spring locking portion A12b is formed in a substantially hook shape so that one end of the biasing spring 18 can be locked.

  Correspondingly, a through groove portion 11b having a predetermined length along the radial direction is formed at a predetermined portion of the annular flat surface portion 11p of the fixed frame member 11. Thereby, when the rotation drive member 12 is accommodated in a predetermined portion of the internal space portion of the fixed frame member 11, the coil spring locking portion A12b penetrates the through groove portion 11b and the outer surface side (circular circle) of the fixed frame member 11 is obtained. It protrudes and is arrange | positioned in the ring plane part 11p. In this state, when the rotation driving member 12 receives the driving force of the stepping motor 16 and rotates, the coil spring locking portion A12b is configured to move along the through groove portion 11b.

  On the other hand, on the outer surface side of the fixed frame member 11 (one side surface side of the annular flat surface portion 11p), a coil spring engagement projecting in the vicinity of the through groove portion 11b in the same direction as the coil spring locking portion A12b. Stop part B11c is formed. The tip of the coil spring locking portion B11c is formed in a substantially hook shape so that the other end of the biasing spring 18 can be locked. The other end of the biasing spring 18 is locked to the coil spring locking portion B11c.

  As described above, one end of the urging spring 18 that is an urging member such as a coiled coil spring is locked to the coil spring locking portion A12b. With this configuration, the rotation drive member 12 disposed so as to be rotatable with respect to the fixed frame member 11 is always urged toward one rotation direction by the urging spring 18. In this case, the urging direction of the rotation driving member 12 by the urging spring 18 is, for example, a direction in which the plurality of blade members 13 driven by the rotation of the rotation driving member 12 narrows the optical path diameter (referred to as a closing direction). . In addition to this example, the biasing direction of the rotary drive member 12 by the biasing spring 18 may be a direction in which the optical path diameter is in an open state (referred to as an opening direction).

  On the other hand, a plurality of cam grooves 12c having a predetermined cam curve are formed in a planar portion that forms an annular shape of the rotation drive member 12. In the plurality of cam grooves 12c, driven pins 13c (described later) of the plurality of blade members 13 are cam-fitted. That is, the plurality of cam grooves 12c serve as driving units that drive the plurality of blade members 13, respectively. Therefore, the plurality of cam grooves 12 c are formed in the same number as the plurality of blade members 13. In the present embodiment, an example in which seven blade members 13 are arranged is shown. Therefore, in this example, seven cam grooves 12c are formed.

  The plurality of blade members 13 are arranged so as to overlap each other, thereby forming a substantially circular opening, and each of the blade members 13 performs a predetermined movement, thereby changing the aperture diameter and adjusting the amount of light passing therethrough. It is a light shielding member. Each of the plurality of blade members 13 is configured by, for example, a thin sheet member. As described above, in the present embodiment, an example constituted by seven blade members 13 is shown.

  Each of the plurality of blade members 13 is pivotally supported on a support shaft (not shown in FIGS. 1 and 2) of the fixed frame member 11 so as to be rotatable about each base. And stored in the internal space. At this time, each of the driven pins 13 c of the plurality of blade members 13 is cam-fitted in each of the plurality of cam grooves 12 c of the rotation driving member 12.

  In this manner, the opening portion of the fixed frame member 11 is covered with the lid member 14 in a state where the rotation driving member 12 and the plurality of blade members 13 are accommodated in the internal space of the fixed frame member 11. In this case, the fixed frame member 11 and the lid member 14 are fastened and fixed by, for example, a plurality of screws 19 or the like.

  The lid member 14 is formed in a substantially annular shape having substantially the same diameter as the fixed frame member 11, and has a circular opening 14a at a substantially central portion thereof. The lid member 14 covers the opening portion of the fixed frame member 11 and prevents members (such as the rotation drive member 12 and the plurality of blade members 13) housed in the internal space of the fixed frame member 11 from dropping off. It serves as a restraining member.

  Each driven pin 13c (described later) of each blade member 13 accommodated in the internal space is engaged with the inner surface side of the lid member 14 (the surface facing the internal space of the fixed frame member 11). A bottomed groove 14b for guiding the movement of the 13 driven pins 13c is formed. The lid member 14 is formed with a plurality of cutout portions 14c (the same number as the blade members 13) for exposing the vicinity of the base end portion that is the rotation center of each blade member 13 housed in the internal space. Yes.

  Further, a torsion spring locking portion A 14 d for hooking one arm 15 b (described later; see FIG. 4) of the torsion spring 15 and a main body portion 15 c of the torsion spring 15 are provided in the vicinity of the notch portion 14 c of the lid member 14. A spring support shaft 14e for winding and holding is provided (not shown in FIGS. 1 and 2; see FIGS. 3 and 4). The torsion spring locking portion A14d and the spring support shaft 14e are formed so as to protrude outward from the outer surface side of the flat surface portion of the annular shape of the lid member 14. The tip of the torsion spring locking portion A14d is formed in a substantially hook shape so that one arm 15b of the torsion spring 15 can be locked. One arm 15b of the torsion spring 15 is locked to the torsion spring locking portion A14d. The tip of the spring support shaft 14e is formed in a substantially hook shape so that the main body 15c of the torsion spring 15 does not fall out.

  The torsion spring 15 is a biasing member that always biases the blade member 13 in one direction so that the diameter of the plurality of blade members 13 is closed or opened. In the present embodiment, it is assumed that the direction of the urging force of the torsion spring 15 is set so that the blade member 13 is in the closing direction.

  Here, the detailed configuration of the torsion spring 15 itself will be described with reference to FIG. FIG. 7 is an enlarged perspective view showing the torsion spring 15 applied to the light amount adjusting device 10 of the present embodiment in an enlarged manner.

  The torsion spring 15 has a main body 15c wound in a coil shape, one arm 15b extending from one end of the main body 15c, and another arm 15a extending from the other end of the main body 15c. Is formed. The torsion spring 15 is a biasing member that uses a biasing force in the torsional direction. One torsion spring 15 is provided corresponding to each of the plurality of blade members 13.

  As shown in an enlarged view in FIG. 4, the main body portion 15c of the torsion spring 15 is wound around the spring support shaft 14e. The spring support shaft 14e is disposed substantially coaxially with the support shaft provided on the fixed frame member 11 that rotatably supports the blade member 13. One arm 15 b of the torsion spring 15 is locked to a torsion spring locking portion A 14 d of the lid member 14, and the other arm 15 a is locked to a torsion spring locking portion B 13 e provided on the blade member 13.

  Further, the light amount adjusting device 10 of the present embodiment has a position sensor 20 that detects the position of the rotation drive member 12. As the position sensor 20, for example, a photointerrupter or the like is applied. The position sensor 20 is arranged in a predetermined portion inside the housing portion in which the fixed frame member 11 and the lid member 14 are combined, that is, in a concave portion indicated by reference numeral 14f in FIG. And fixed to the casing. Correspondingly, a light-shielding blade portion 12 e that acts on the position sensor 20 is formed on the outer peripheral edge portion of the rotation driving member 12. And this light-shielding blade | wing part 12e is comprised so that it can pass between the light transmission / reception parts of the said position sensor 20. FIG.

  5 and 6 are enlarged views showing the blade member 13 applied to the light amount adjusting device 10 of the present embodiment. Among these, FIG. 5 is a plan view of the blade member 13. FIG. 6 is a side view of the blade member 13.

  As illustrated, the blade member 13 is a light shielding member formed of, for example, a thin plate-like sheet member as described above. The blade member 13 is formed in a substantially lunate shape and is cam-fitted into the main blade portion 13a which is the main portion of the blade member 13 and the cam groove 12c of the rotation driving member 12 to drive the blade member 13. A driven pin 13c, a torsion spring locking portion B13e for locking the other arm 15a of the torsion spring 15, a support portion 13h having a through hole 13d through which the support shaft of the fixed frame member 11 passes, and the like. ing.

  The plurality of blade members 13 configured as described above are rotatably supported by a plurality of support shafts provided on the fixed frame member 11. This configuration will be specifically described as follows. In other words, for example, on the other side surface side (inner side surface of the internal space portion) of the annular flat surface portion 11p of the fixed frame member 11, the number of the support shafts corresponds to each of the plurality of blade members 13 (in this embodiment). 7) and are planted over the entire circumference at predetermined intervals in the radial direction.

  And the through-hole 13d of the support part 13h provided in the base part of each blade | wing member 13 is each penetrated with respect to each of said several spindle. Accordingly, the blade member 13 is pivotally supported so as to be rotatable about the support shaft 11e as a central axis. At this time, the blade member 13 is housed and disposed in the internal space of the fixed frame member 11. Therefore, the blade member 13 is housed and disposed in the inner space of the fixed frame member 11 so as to be rotatable within a predetermined range.

  FIG. 8 is a diagram showing only the blade member 13 and the rotation drive member 12 in the state where the amount of light passing through the light amount adjusting device 10 is maximized (open state). FIG. 9 is a diagram showing only the blade member 13 and the rotation driving member 12 in a state where the amount of light passing through the light amount adjusting device 10 is minimized (minimum aperture state). FIG. 10 is an enlarged view for showing the relationship between the blade member 13 and the rotary drive member 12 at a viewpoint fixed to the rotary drive member 12.

  As shown in FIG. 10, when the rotation driving member 12 and the fixed frame member 11 are relatively rotated around the optical axis L, the blade member 13 is fixed by the engagement of the cam groove 12c and the driven pin 13c. It rotates around a support shaft provided on the frame member 11. The support shaft of the blade member 13 is parallel to the optical axis L, and the main blade portion 13a moves so as to approach or move away from the optical axis L when the blade member 13 rotates around the support shaft. In the light amount adjusting device 10, the shape of the opening through which the light beam can pass is determined by the edge portion 13i of the main blade portion 13a of the plurality of diaphragm blades 13 disposed around the opening 10a.

  As shown in FIG. 9, when the rotation driving member 12 is driven by the stepping motor 16 in the closing direction (direction indicated by arrow C in FIG. 9) relative to the fixed frame member 11 around the optical axis L. The plurality of blade members 13 rotate in a direction in which the main blade portion 13a approaches the optical axis L, and the area of the opening through which the light beam can pass becomes narrow.

  Further, as shown in FIG. 8, the stepping motor 16 causes the rotation driving member 12 to move relative to the fixed frame member 11 around the optical axis L in the opening direction that is opposite to the closing direction (arrow O in FIG. 8). When driven in the direction indicated by), the plurality of blade members 13 rotate in a direction in which the main blade portion 13a moves away from the optical axis L, and the area of the opening through which the light beam can pass is widened.

  FIG. 11 is a graph showing the relationship between the rotation angle of the rotation drive member 12 and the area of the aperture through which the light beam can pass in the light amount adjusting device 10. In FIG. 11, the horizontal axis indicates the rotation angle R of the rotary drive member 12, and the vertical axis indicates the AV value. On the horizontal axis, 0 is a so-called open state in which the area of the opening is the largest in the light amount adjusting device 10, and the rotation angle of the rotary drive member 12 in the closing direction increases as the horizontal axis moves to the right. Regarding the vertical axis, the intersection of the vertical axis and the horizontal axis is the AV value in the open state. As the AV value increases, that is, as the vertical axis increases, the area of the opening of the light amount adjusting device 10 decreases.

  As shown in FIG. 11, in the light amount adjusting apparatus 10 of the present embodiment, the relationship between the rotation angle R of the rotation drive member 12 and the AV value is not a linear relationship, and the AV value changes as the rotation angle R increases. The amount increases. That is, the line indicating the relationship between the rotation angle R of the rotation drive member 12 and the AV value is not a straight line but a downwardly convex curve in which the inclination of the curve increases as the rotation angle R increases.

  In the present embodiment, the rotational drive member 12 is configured to be rotationally driven by the stepping motor 16, and thus the amount of change in the AV value per minimum drive unit angle (one step) of the stepping motor 16 is not constant. As the AV value increases (the narrower), the amount of change in the AV value per minimum drive unit angle of the stepping motor 16 increases. In other words, the amount of change in the AV value per pulse, which is the shortest signal for driving the stepping motor 16, increases as the AV value increases (is narrowed down).

  More specifically, in the present embodiment shown in FIG. 11, the relationship between the rotation angle R of the rotation drive member 12 and the AV value is expressed by a quadratic function. Note that the relationship between the rotation angle R of the rotation driving member 12 and the AV value from the open F value of the lens apparatus having the light amount adjustment device 10 may be a relationship in which the inclination increases as the rotation angle R increases. The above higher-order curve relationship may be used.

  As described above, in the light amount adjusting apparatus 10 of the present embodiment, the amount of change in the AV value per minimum driving unit angle of the stepping motor 16 increases as the AV value increases, that is, as the minimum aperture state is approached. For this reason, the rotation angle of the stepping motor 16 required for the transition from the open state to the minimum aperture state can be reduced, and the time required for the transition from the open state to the minimum aperture state can be shortened.

  Note that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. The apparatus is also included in the technical scope of the present invention.

  Needless to say, the light amount adjustment device according to the present invention is not limited to a form provided in a so-called still camera, but may be provided in an electronic apparatus having an imaging function such as a video camera or a mobile communication terminal.

10 Light quantity adjustment device,
10a opening,
11 Fixed frame member,
11a opening,
11b through groove,
11d screw hole,
11c Coil spring locking part,
11f through hole,
11m outer wall surface,
11n inner wall surface,
11p circular plane part,
12 Rotation drive member,
12b Coil spring locking part A,
12c cam groove,
12d sector gear,
12e shading blade,
13 blade member,
13a main blade part,
13c driven pin,
13d through hole,
13e Torsion spring locking part,
13h support part,
13i edge,
14 Lid member,
14a opening,
14b bottomed groove,
14c Notch,
14d Torsion spring locking part A,
14e spring support shaft,
15 Torsion spring,
15a other arm,
15b one arm,
15c body part,
16 Stepping motor,
16a pinion gear,
17 screws,
18 Biasing spring,
19 Screw,
20 position sensor,
L Optical axis.

Claims (3)

A fixed frame member having an opening which is a through hole through which the optical axis passes;
An annular rotary drive member rotatable around the optical axis relative to the fixed frame member;
A plurality of cam grooves formed in the rotation drive member;
Around the optical axis, a plurality of blades that are rotatably arranged around an axis parallel to the optical axis provided on the fixed frame member, and are each provided with a driven pin that engages with the cam groove Members,
A stepping motor that rotationally drives the rotational drive member;
A light amount adjusting device capable of changing the aperture of the opening formed by each edge of the plurality of blade members,
The shape of the cam groove is determined so that the relationship between the rotation angle of the rotation drive member and the amount of change in the AV value increases as the rotation angle increases in the direction in which the AV value increases. A characteristic light amount adjusting device.   The light amount adjusting apparatus according to claim 1, wherein a relationship between the rotation angle and the amount of change in the AV value is along a higher order curve.   The light amount adjusting device according to claim 2, wherein a relationship between the rotation angle and the change amount of the AV value is along a quadratic curve.

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