JP2018200336A - Light amount adjustment device - Google Patents

Abstract

To provide a light amount adjustment device which restricts variation in precision of an aperture diameter between a completely open position and a minimal diaphragm position of an optical path aperture, by inhibiting looseness of a rotary plate that performs opening and closing operation of multiple diaphragm blades.SOLUTION: A light amount adjustment device comprises: multiple diaphragm blades 15 changing an aperture diameter of an optical path aperture 12; a rotary plate 14 turning to move the multiple diaphragm blades 15 along the optical path aperture 12; a cam plate 17 guiding an opening and closing direction of the multiple diaphragm blades 15 with turning of the rotary plate 14; and a base plate 13 turnably supporting the rotary plate 14. Further, the light amount adjustment device is provided with: energizing means 31 energizing the rotary plate 14 to a diaphragm blade 15 side; and energization force adjusting means 41 changing energization force of the energizing means 31 applied to the rotary plate 14 with turning of the rotary plate 14 by abutting on the energizing means 31.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light amount adjustment device that is mounted on an imaging device such as a video camera or a still camera, or a projector or other projection device, and adjusts the light amount in shooting or projection.

  In general, this type of light quantity adjusting device has a ring-shaped rotary plate having an optical path opening corresponding to a photographing (projection) optical path, and a plurality of aperture blades for adjusting the light quantity are arranged along the rotary plate so as to be opened and closed. Thus, the amount of light taken into the optical path opening is adjusted from fully open to the minimum aperture (Patent Documents 1-3).

  In Patent Documents 1-3, a plurality of diaphragm blades are arranged around an optical path opening provided in a rotary plate, and the iris for narrowing the optical path opening into a circular shape from a small diameter to a large diameter by the plurality of diaphragm blades. A light amount adjusting device employing an aperture method is disclosed. Such a light quantity adjusting device can perform a diaphragm operation so that the opening diameter changes stepwise.

  The light amount adjusting device includes a ring-shaped rotary plate and a cam plate each having a circular optical path opening, and a plurality of the light quantity adjusting devices disposed between the rotary plate and the cam plate and arranged in a scale shape along the peripheral surface of the optical path opening. And a driving mechanism for rotating the rotary plate in a predetermined direction to open and close the plurality of diaphragm blades. The rotary plate is provided with a plurality of support holes for rotatably supporting each diaphragm blade, and the cam plate has a cam hole for guiding each diaphragm blade so as to be opened and closed along the optical path opening. The plurality of aperture blades are arranged so that the base ends of adjacent aperture blades circulate while overlapping. That is, the diaphragm blades are sequentially placed on the upper side while being shifted, and a part (end) of the last diaphragm blade is arranged in a plane in the circumferential direction so as to overlap the lower side of the first diaphragm blade. Become. The plurality of diaphragm blades arranged in this way can narrow the optical path opening to a predetermined opening diameter by rotating in a predetermined direction via a rotary plate and a cam plate.

JP 2010-276654 A JP 2012-237790 A JP2013-020165A

  In the light quantity adjusting device, it is known that the posture of each diaphragm blade that opens and closes on the optical path opening affects the aperture accuracy. For this reason, it is desirable to minimize the distance between the rotary plate on which the diaphragm blades are disposed and the cam plate. However, in order to hold the rotary plate freely, a certain distance between the base plate and the drive mechanism is required. It is necessary to secure space.

  However, by ensuring such a space, the rotary plate is likely to rattle, and as a result, the interval between the rotary plate and the cam plate varies irregularly. As a result, there is a problem in that the postures of the diaphragm blades vary and the aperture accuracy decreases.

  Therefore, the present invention can prevent variation in aperture accuracy between the fully open position of the optical path opening and the minimum aperture position by preventing the rotary plate that performs the opening and closing operation of the plurality of aperture blades. An object is to provide a light amount adjusting device.

  In order to solve the above-described problems, a light amount adjusting device according to the present invention includes a plurality of diaphragm blades that change the aperture of an optical path opening, and a rotary plate that rotates to move the plurality of diaphragm blades along the optical path opening. And a light amount adjusting device comprising: a cam plate that guides the opening and closing directions of the plurality of aperture blades as the rotary plate rotates; and a base plate that rotatably supports the rotary plate. Biasing means for biasing on the diaphragm blade side is provided, and biasing force adjusting means for changing the biasing force of the biasing means against the rotary plate in contact with the biasing means and rotating the rotary plate is provided. Provided.

  According to the light amount adjusting device of the present invention, rattling when the rotary plate rotates can be suppressed by the biasing means that biases the rotary plate toward the diaphragm blade. Further, by providing the urging force adjusting means for changing the urging force of the urging means with respect to the rotary plate, the optical path opening can be opened and closed by an appropriate urging force according to the opening / closing position of each aperture blade.

  Further, the biasing force adjusting means includes a biasing guide having a height difference, and the biasing guide has an inclined surface that gradually increases from the fully open position of the optical path opening toward the minimum aperture position. The urging force can be increased with respect to the direction of suppressing the rising of each diaphragm blade. As a result, it is possible to reduce variations in aperture accuracy at the minimum aperture position.

It is a disassembled perspective view of the light quantity adjustment apparatus of this invention. It is a perspective view before the assembly | attachment of a base plate and a rotary plate. It is principal part sectional drawing of a light quantity adjustment apparatus. It is a perspective view of the base plate equipped with the urging means. It is the perspective view which showed the rotational position of the rotary plate when an optical path opening is fully opened. It is sectional drawing of FIG. It is the perspective view which showed the rotational position of the rotary plate when an optical path opening was made into the minimum aperture stop. It is sectional drawing of FIG.

  Hereinafter, with reference to the drawings, an embodiment of a light amount adjusting device according to the present invention will be described in detail. FIG. 1 is an exploded view showing the configuration of the light amount adjusting device 11. The light quantity adjusting device 11 includes a base plate 13 having a rotation drive unit, a rotary plate 14 rotatably held on the base plate 13, a plurality of diaphragm blades 15 disposed on the rotary plate 14, and a plurality of diaphragm blades. The cam plate 17 that opens and closes the cam plate 15 and the cover plate 18 that covers the cam plate 17 are assembled so that the optical path openings 12 centering on the optical axis O coincide with each other.

  Each of the diaphragm blades 15 opens and closes the optical path opening 12 in a circular shape while sequentially overlapping, thereby adjusting the diaphragm of the light amount.

  As shown in FIG. 2, the rotary plate 14 has an engagement step portion 22 along the inner peripheral surface of the optical path opening 12 on the side facing the base plate 13, and this engagement step portion 22 is used as the optical path opening of the base plate 13. 12 to be assembled. The engagement step portion 22 is provided with a plurality of engagement pieces 26 toward the outside of the optical path opening 12, and the engagement pieces 26 are provided along the inner peripheral surface of the optical path opening 12 of the base plate 13. Insert into the engagement hole 27. And it engages by shifting to a predetermined rotation angle. On the inner side of the engagement piece 26, there is provided a sliding projection 30 that contacts the bottom surface of the base plate 13. As described above, the engagement piece 26 slidably sandwiches the back surface side of the base plate 13 to secure a space in which the rotary plate 14 can rotate with respect to the base plate 13.

  Passive teeth 28 are formed on a part of the outer peripheral portion of the rotary plate 14. The passive teeth 28 are provided at positions that mesh with a rotation gear 29 of a rotation drive unit (drive motor) M attached to the base plate 13. Then, by rotating the drive motor M forward and backward, the rotary plate 14 slides clockwise or counterclockwise in the circumferential direction with respect to the base plate 13, and the plurality of aperture blades 15 are closed along with this slide. Rotate between the direction and the opening direction.

  As shown in FIG. 3, the plurality of aperture blades 15 are arranged to be opened and closed in a sliding space S between the rotary plate 14 and the cam plate 17. When the optical path opening 12 is fully opened, it fits in the sliding space S between the rotary plate 14 and the cam plate 17, and when narrowing down to the minimum, each diaphragm blade 15 spreads like a scale, The front end portions 15a are supported with each other. In the present embodiment, as shown in FIG. In the case of such seven sheets, when the optical path opening 12 is fully opened, an overlapping portion of the three diaphragm blades 15 is generated in the sliding space S between the rotary plate 14 and the cam plate 17. Therefore, the sliding space S needs an interval that can accommodate the three diaphragm blades 15.

  The sliding space S is set according to the height of the engaging step portion 22 provided on the rotary plate 14. In the present invention, a biasing means 31 that biases the rotary plate 14 toward the diaphragm blade 15 is provided. At the same time, an urging force adjusting means for changing the urging force of the urging means 31 against the rotary plate 14 as the rotary plate 14 rotates is provided. The urging force adjusting means is formed by an urging guide 41 that has a height difference and abuts against the diaphragm blade 15. This makes it possible to prevent the rotary plate 14 from rattling caused by having the sliding space S in accordance with the opening / closing operations of the plurality of aperture blades 15.

  As shown in FIG. 2, the urging means 31 includes a ring-shaped support portion 34 that is mounted along the outer periphery of the engagement step portion 22 of the rotary plate 14, and an outward direction from the outer peripheral surface of the support portion 34. Are integrally formed by a plurality of connecting portions 33 projecting from the connecting portion 33 and a leaf spring portion 32 extending in an arc shape along the inside of the outer peripheral surface of the rotary plate 14. When the rotary plate 14 is made to face the surface side of the base plate 13 with the surface on which the biasing means 31 is mounted turned upside down, the biasing means 31 follows the outer peripheral surface of the optical path opening 12 of the base plate 13. It is attached to the fitting recess 42 formed.

  FIG. 4 shows a state in which the biasing means 31 is mounted in the fitting recess 42, and has a biasing force inclined upward from the base end portion 32b of the leaf spring portion 32 toward the tip end portion 32a. The tip 32a is provided with a sliding projection 35 that contacts the biasing guide 41.

  The urging guide 41 has an inclined surface protruding in an arc shape along the direction in which the leaf spring portion 32 of the urging means 31 extends. The urging guide 41 abuts on a sliding projection 35 provided at the tip 32 a of the leaf spring portion 32 of the urging means 31 and is formed with a length along the rotational range of the rotary plate 14. .

  5 and 6 show the rotational position of the rotary plate 14 in a state where the plurality of aperture blades 15 are opened and the optical path opening 12 is fully opened. In this state, the distal end portion 32a of the leaf spring portion 32 of the urging means 31 is in contact with the low portion 41a of the urging guide 41, so that the rotary plate 14 is moved to the plurality of aperture blades 15 (not shown) with the lowest urging force. To the side). For this reason, rattling can be prevented without excessively pressing the rotary plate 14, and the rotary plate 14 can be smoothly rotated.

  7 and 8 show the rotational position of the rotary plate 14 in a state where the plurality of aperture blades 15 are closed and the optical path opening 12 is minimized. In this state, the distal end portion 32a of the plate spring portion 32 of the urging means 31 is in contact with the height 41b of the urging guide 41, so that the rotary plate 14 is moved to the plurality of aperture blades 15 (not shown) with the strongest urging force. To the side). In such a minimum aperture position, the overlapping portions of the aperture blades 15 increase, and the jump at the tip portion of the aperture blades 15 thereby increases. Therefore, the rotary plate 14 rattles by suppressing the pressure caused by the spring-up. Can be prevented.

  The urging guide 41 with which the leaf spring portion 32 abuts is provided in accordance with the rotation radius of the rotary plate 14 where the plurality of aperture blades 15 rotate between the position where the optical path opening 12 is fully opened and the minimum aperture position. A tapered inclined surface that gradually increases from the fully open position toward the minimum aperture position is formed.

  The rotary plate 14 is provided with a rotation shaft hole 25 that engages with a rotation shaft pin 24 provided at the base end portion of each diaphragm blade 15, and the cam plate 17 has a rotation shaft of each diaphragm blade 15. A cam hole 19 slidably engaged with a cam pin 23 protruding on the opposite side of the pin 24 is provided.

  The cam holes 19 are provided according to the number of the diaphragm blades 15, and the cam pins 23 move along the cam holes 19 by the rotation of the rotary plate 14, so that the leading ends of the diaphragm blades 15 are mutually connected. The optical path opening 12 can be closed or opened in a circular shape while overlapping.

  The cover plate 18 has an outer shape corresponding to a lens barrel shape of an imaging device (not shown) to be mounted, and is formed with a material and dimensions suitable for the light amount adjusting device 11 by metal or synthetic resin. . A plurality of cam grooves 21 corresponding to the plurality of cam holes 19 formed in the cam plate 17 are formed in the cover plate 18. As shown in FIG. 3, the cover plate 18 is assembled to the base plate 13 with the cam plate 17 disposed on the back surface side and having a space for accommodating the plurality of aperture blades 15 and the rotary plate 14.

  In the present invention, when the rotary plate 14 rotates by providing the biasing means 31 between the rotary plate 14 that drives the plurality of aperture blades 15 and the base plate 13 that supports the rotation of the rotary plate 14. It has become possible to greatly reduce shakiness and noise. Further, by providing a biasing guide 41 having a height difference for changing the biasing force of the biasing means 31 on the side of the rotary plate 14 with which the biasing means 31 abuts, the aperture of the optical path opening 12 is adjusted. By obtaining an optimal urging force according to the opening / closing positions of the plurality of aperture blades 15, it is possible to perform an aperture operation with high accuracy.

  The plurality of biasing guides 41 are formed in accordance with a rotation range regulated by the passive teeth 28 of the rotary plate 14. The rotation range of the rotary plate 14 restricted by the passive teeth 28 corresponds to the reciprocation distance between the fully open position of the optical path opening 12 and the minimum stop position by the plurality of stop blades 15. The plurality of leaf spring portions 32 and the plurality of urging guides 41 are at least at three locations and equidistant from each other in the circumferential direction of the base plate 13 and the rotary plate 14 in order to maintain a rotational balance by the plurality of diaphragm blades 15. It is preferable to provide in.

O Optical axis M Drive motor S Sliding space 11 Light quantity adjusting device 12 Optical path opening 13 Base plate 14 Rotary plate 15 Aperture blade 15a Tip 17 Cam plate 18 Cover plate 19 Cam hole 21 Cam groove 22 Engaging step 23 Cam pin 24 Rotating shaft Pin 25 Rotating shaft hole 26 Engaging piece 27 Engaging hole 28 Passive tooth 29 Rotating gear 30 Sliding projection 31 Biasing means 32 Leaf spring portion 32a Tip portion 32b Base end portion 33 Connecting portion 34 Supporting portion 35 Sliding projection 41 With Force guide (biasing force adjustment means)
41a Low part 41b High part 42 Fitting recess

Claims (5)

A plurality of diaphragm blades that change the aperture of the optical path opening, a rotary plate that rotates to move the plurality of diaphragm blades along the optical path opening, and the plurality of diaphragm blades as the rotary plate rotates In a light amount adjusting device comprising a cam plate that guides the opening and closing direction and a base plate that rotatably supports the rotary plate,
An urging means for urging the rotary plate toward the diaphragm blades is provided, and an urging force for changing the urging force of the urging means with respect to the rotary plate in contact with the urging means and rotating the rotary plate. A light amount adjusting device provided with a force adjusting means. The biasing means includes a plurality of leaf springs arranged along the direction in which the rotary plate rotates,
2. The light amount adjusting device according to claim 1, wherein the urging force adjusting means includes a plurality of urging guides corresponding to the leaf spring portions and having a height difference with respect to a direction in which the leaf spring portions abut. .   The light amount adjusting device according to claim 2, wherein the urging force adjusting means has a tapered inclined surface that is inclined along a rotation direction of the rotary plate.   The light amount according to any one of claims 1 to 3, wherein the biasing force adjusting means is inclined so as to gradually increase from a position at which the optical path opening is fully opened by the plurality of aperture blades toward a direction in which the optical path is reduced to the minimum diameter. Adjustment device.   The light amount adjusting device according to claim 1, wherein the urging unit is provided between the base plate and the rotary plate, and the urging force adjusting unit is provided on the rotary plate.

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