Light intensity control devices and optical instruments

Abstract

To provide a light intensity control device that facilitates miniaturization of the aperture and shutter. [Solution] To solve the above problems, the light intensity adjustment device of the present invention comprises a base member 101 having a fixed aperture 101a through which light passes; a plurality of aperture blades 116 that move in a plane perpendicular to the optical axis to form an aperture smaller than the fixed aperture; a drive source 102 that moves the aperture blades; a light intensity adjustment member 104 that moves back and forth in the fixed aperture to adjust the amount of light; and a drive source 110 that operates the light intensity adjustment member. At least one of the light intensity adjustment members 104 is positioned between the aperture blade guide shafts 101b and 101c, which are installed on the base member 101.

Description

Technical Field

[0001] The present invention relates to a light amount adjusting device mounted on an optical device such as an imaging device or an interchangeable lens. The present invention also relates to an optical device provided with the light amount adjusting device.

Background Art

[0002] A light amount adjusting device mounted on an optical device such as a digital camera or a video camera drives a stepping motor or the like as a drive source, rotates a diaphragm blade via a rotating member configured with gears, and changes the area of the light passage opening to adjust the amount of light passing through the device, or includes a moving magnet type electromagnetic drive unit as a drive source and a dimming filter that advances and retreats in the light passage opening to cover and open the light passage opening. (See Patent Document 1).

[0003] Patent Document 1 discloses a light amount adjusting device that uses a moving magnet type electromagnetic drive unit as a drive source to move a shutter blade and a diaphragm blade forward and backward in a light passage opening.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the configuration disclosed in Patent Document 1, since the drive sources of the diaphragm and the shutter and their blades are arranged over the entire circumferential direction, the device is likely to be enlarged over the entire circumferential direction.

[0006] The present invention provides a light amount adjusting device capable of reducing the size of the device and an optical device provided with the same.

Means for Solving the Problems

[0007] To solve the above problems, the light intensity adjustment device of the present invention comprises a base member provided with an opening through which light passes; a plurality of aperture blades that move in a direction perpendicular to the optical axis of the light passing through the opening and move back and forth relative to the opening to form a smaller aperture than the opening; a first drive unit positioned away from the opening and moving the plurality of aperture blades back and forth; a plurality of guide shafts provided on the base member and guiding the aperture blades; a light intensity adjustment member that moves back and forth relative to the opening; and a second drive unit that rotates a magnet to operate the light intensity adjustment member, wherein the light intensity adjustment member is positioned between the plurality of guide shafts. [Effects of the Invention]

[0008] According to the present invention, space can be used effectively, and a light intensity adjustment device equipped with a light intensity adjustment member and aperture for light reduction or shading can be made smaller. [Brief explanation of the drawing]

[0009] [Figure 1] Front view of the light intensity control device according to Example 1 [Figure 2] Rear view of the light intensity control device according to Example 1 [Figure 3] Perspective view of the light intensity control device according to Example 1 [Figure 4] Exploded perspective view of the light intensity control device according to Example 1 [Figure 5] Operation diagram of the shutter of the light intensity control device according to Example 1 [Figure 6] Operation diagram of the aperture of the light intensity control device according to Example 1 [Figure 7] Front view of the light intensity control device according to Example 2 [Figure 8] Rear view of the light intensity control device according to Example 2 [Figure 9] Exploded perspective view of the light intensity control device according to Example 2 [Figure 10] Operation diagram of the ND filter of the light intensity control device according to Example 2 [Figure 11] Operation diagram of the ND filter of the light intensity control device according to Example 3 [Figure 12] Schematic diagram of an imaging device equipped with the aperture device of Example 1.

Embodiments for Carrying Out the Invention

[0010] (Example 1) Embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6.

[0011] FIG. 1 is a plan view of a light quantity adjustment device according to an embodiment of the present invention. A rear view of the light quantity adjustment device is shown in FIG. 2, a perspective view of the light quantity adjustment device is shown in FIG. 3, and an exploded perspective view of the light quantity adjustment device is shown in FIG. 4. FIG. 5 shows an operation diagram of the shutter of the light quantity adjustment device, and FIG. 6 shows an operation diagram of the aperture.

[0012] In these figures, the base member 101 is a member that supports the structure of the shutter, and a fixed aperture (opening) 101a through which light passes is provided. Among the outer surfaces (one surface in the optical axis direction) of the base member 101, a later-described aperture drive unit 102 and a shutter drive unit 110 are attached at positions away from the fixed aperture 101a.

[0013] The aperture drive unit 102 is attached to the base member 101 and serves as a drive source for the aperture. The aperture drive unit 102 can use an electromagnetic actuator such as a stepping motor or a galvanometer. The aperture drive unit includes an output shaft 102b, and by electrically controlling the aperture drive unit 102, it can be rotated at an arbitrary angle.

[0014] The drive arm 103 has pin drive pins 103i and 103j as transmission parts for driving a later-described aperture blade group 116 at both ends sandwiching the position of the output shaft 102b. The pin drive pin 103i is engaged with the aperture blade 117, and the pin drive pin 103j is engaged with the aperture blade 118. The aperture drive arm 103 is fixed to the output shaft 102b of the aperture drive unit by press-fitting or adhesion, etc., and rotates around the output shaft 102b as the rotation center, and the aperture drive lever 103 also rotates in accordance with the rotation of the output shaft 102b.

[0015] The aperture blade group 116 consists of two aperture blades 117 and 118. The aperture blades 117 and 118 are thin plate-like members having light shielding properties, and have drive long holes 117i and 118j through which the blade drive pins 103i and 103j are inserted. The aperture blades 117 and 118 are formed by press-molding a thin resin sheet coated with a light shielding paint, or by press-molding a thin metal plate subjected to a lubrication treatment, or by mold molding so as to be in a thin plate shape.

[0016] Next, the structure of the shutter unit will be described. The base member 101 is a member that serves as a substrate of the light quantity adjustment device 100, and a device opening 101a for allowing light to pass through is formed.

[0017] The cutting member 109 is assembled parallel to the base member 101 such that the fixed opening 101a and the fixed opening 109a are coaxial, and forms a shutter blade chamber in which the shutter blade group 104 is housed between the base member 101 and the partitioning member 109.

[0018] As described above, the shutter drive unit 110 is attached to the outer surface (one surface in the optical axis direction) of the base member 101.

[0019] The magnet 111 has its outer peripheral surface magnetized to two poles (N pole, S pole). The shutter drive lever 112 is configured integrally with the magnet 111. Examples of the integral method include fixing with an adhesive, and in the case of resin, insert injection molding. The magnet 111 and the shutter drive lever 112 configured integrally are supported by a drive lever rotation shaft (not shown) provided on the base member 101 and can perform a rotational movement.

[0020] The stator yoke 113 made of a soft magnetic material is disposed on the outer peripheral curved surface of the magnet 111. The electromagnetic coil unit 114 is configured by winding a coil made of a conducting wire around a bobbin. This electromagnetic coil unit 114 is attached to the base member 101 in a state where the stator yoke 113 is inserted.

[0021] The actuator cover 115 is attached to the base member 101 and holds the stator yoke 113 and the shutter drive lever 112.

[0022] As shown in the figure, the magnet 111, shutter drive lever 112, stator yoke 113, electromagnetic coil unit 114, and actuator cover 115 are assembled to form an electromagnetic actuator, which becomes the shutter drive unit 110 and drives the shutter blade group 104 described later.

[0023] The shutter blade group 104 consists of multiple shutter blades, and the light intensity adjustment device in this embodiment consists of four shutter blades 105, 106, 107, and 108. As a light intensity adjustment member that is operated by rotating a magnet, the above-mentioned shutter blades (light-shielding blades), aperture blades, or neutral density filters such as ND filters can be used.

[0024] Next, the operation of the shutter will be explained with reference to the diagram. Figure 5(a) shows the shutter blades 105, 106, 107, and 108 retracted from the fixed aperture 101a, which serves as the light passage.

[0025] Figure 5(b) shows the shutter blades 105, 106, 107, and 108 covering the fixed opening 101a, which serves as the light passage.

[0026] The shutter blades 105, 106, 107, and 108 are made of thin, light-shielding plate-like members and have shutter blade rotation holes 105a, 106a, 107a, and 108a and cam holes 105b, 106b, 107b, and 108b. The shutter drive lever 112 is rotated by the shutter drive unit 110, and the shutter blades 105, 106, 107, and 108 rotate around the shutter blade rotation holes 105a, 106a, 107a, and 108a, covering or opening the fixed opening 101a.

[0027] The base member 101 is provided with guide shafts 101b and 101c for the aperture blade group 116. In the retracted state, the shutter blades 105, 106, and 107 are retracted to the side opposite to the side with the guide shafts 101b and 101c relative to the fixed aperture 101a, in a plane perpendicular to the optical axis direction. In the retracted state, the shutter blade 108 is positioned on the side opposite to the aperture drive unit 102 relative to the fixed aperture 101a, in a plane perpendicular to the optical axis direction. Furthermore, the shutter blade 108 is positioned such that a part of its shape fits between the guide shafts 101b and 101c. The rotation hole 108a of the shutter blade 108 is positioned on the side opposite to the side with the guide shafts 101b and 101c relative to the fixed aperture 101a.

[0028] The guide shafts 101b and 101c are designed to be positioned with a certain clearance to avoid collision with the shutter blades 108. Here, if L1 is the length from the rotation hole 108a of the shutter blades 108 to the guide shaft 101b, and L2 is the length from the rotation hole 108a of the shutter blades 108 to the guide shaft 101c, then when L1 = L2, the guide shafts 101b and 101c can be brought closest to the shutter blades 108, making it possible to miniaturize the light intensity adjustment device 100 in the lateral direction.

[0029] Next, the operation of the aperture will be explained with reference to the diagram. Figure 6(a) shows the aperture blades 117 and 118 retracted from the fixed opening 101a of the aperture base plate, which serves as the light passage.

[0030] When the aperture drive unit 102 is rotated clockwise from the state shown in Figure 6(a), the aperture drive lever 103, which is press-fitted onto the output shaft 102b of the aperture drive unit, rotates, causing the blade drive pins 103i and 103j to rotate clockwise. The aperture blade 117 receives force from the cam hole 117i fitted onto the blade drive pin 103i and moves linearly downward in Figure 6 along the guide holes 117b and 117c fitted onto the guide shafts 101b and 101c. The aperture blade 118 receives force from the cam hole 118j fitted onto the blade drive pin 103j and moves linearly upward in Figure 6 along the guide holes 118b and 118c fitted onto the guide shafts 101b and 101c. The aperture formed by the aperture blades 117 and 118, through which light passes, becomes smaller, and the amount of light passing through the light intensity adjustment device 100 can be reduced.

[0031] Figure 6(b) shows the aperture drive unit 102 rotated further from (a). This allows for a further reduction in the amount of light passing through the light intensity control device 100.

[0032] Figure 6(c) shows the state after further rotation of the aperture drive unit 102 from (b). The aperture blades 117 and 118 close the fixed opening 101a, which is the light passage opening, and block out light.

[0033] By rotating the rotation phase of the aperture drive unit 102 to any position, it is possible to change the aperture opening shown in Figures 6(a) to (c) to any area, thereby adjusting the amount of light passing through the light intensity adjustment device 100.

[0034] Furthermore, by rapidly rotating the aperture drive unit 102 from any of the states shown in Figures 6(a) to (b) to the state shown in Figure 6(c), the fixed aperture 101a can be shielded from light, thereby allowing it to be used as a shutter device.

[0035] As shown in Figures 1-6, the shutter blades 108 are positioned between the shafts 101b and 101c for the aperture blade guides, which are installed on the base member 101.

[0036] By arranging the shutter structure and aperture blade guide axis in this way, space can be used effectively, making it possible to miniaturize the external dimensions of the light intensity adjustment device 100.

[0037] (Example 2) The configuration of the light intensity control device 200 of Example 2 of the present invention will be described in detail with reference to Figures 7 to 10. In the configuration of this embodiment, components the same as those in Example 1 are denoted by the same reference numerals.

[0038] Figure 7 is a plan view of the light intensity control device in Example 2. Figure 8 shows a rear view of the light intensity control device, and Figure 9 shows an exploded perspective view of the light intensity control device. Figure 10 shows the operation diagram of the ND filter.

[0039] In these figures, the aperture drive unit 102, aperture drive lever 103, and aperture blade group 116 are substantially the same as those of the aperture device 100 in Embodiment 1.

[0040] Next, I will explain the structure of the neutral density filter. The neutral density filter is sometimes called an ND (Neutral Density) filter, and will be referred to as an ND filter below.

[0041] The ND drive unit 206 is a moving magnet type drive unit consisting of an electromagnetic coil, similar to the shutter drive unit 110 in Embodiment 1. The ND drive lever 207 rotates together with the magnet 109.

[0042] The ND vane 202 consists of an ND filter 204 that reduces the amount of light passing through and an ND retaining vane 203 that holds the ND filter. The ND vane 202 has a vane rotation hole 203a that fits with the vane rotation shaft 201d of the base member and a cam hole 203b that fits with the ND drive lever 207. The ND vane 203 rotates around the vane rotation hole 203a by the ND drive unit 206, moving forward and backward into the device opening (opening) 201a of the base member, and can reduce the amount of light passing through the device opening 201a. The ND vane 202 is positioned so that a part of its shape fits between the guide shafts 201b and 201c.

[0043] In this embodiment, the light intensity adjustment element is an ND filter, but by changing the characteristics of the filter, the same configuration can be used with various optical filters such as IR cut filters and bandpass filters.

[0044] The partition member 205 is mounted parallel to the base member 201, forming an ND vane chamber between the partition member 205 and the base member 201 where the ND vane 202 is housed.

[0045] As shown in Figures 7-10, the ND blade 202 is positioned between the shafts 201b and 201c for the aperture blade guide, which are installed on the base member 201.

[0046] By arranging the ND structure and aperture blade guide axis in this way, space can be used effectively, making it possible to reduce the external size of the light intensity adjustment device 200.

[0047] (Example 3) The configuration of the light intensity control device 300 in Example 3 of the present invention will be described in detail with reference to Figure 11. In the configuration of this embodiment, components the same as those in Example 1 or Example 2 are denoted by the same reference numerals.

[0048] Figure 11 shows the operation diagram of the ND filter in the light intensity control device of Example 3.

[0049] Example 3 is a modification of Example 2 in which the ND vane 202 is replaced with an ND vane 302. While the ND vane 202 of Example 2 consisted of an ND filter and an ND retaining vane that held the ND filter, the ND vane 302 has a vane rotation hole 302a and a cam hole 302b that engages with the ND drive lever 207 in the ND filter base material.

[0050] The ND blade 302 is positioned such that a portion of its shape fits between the guide shafts 301b and 301c. The operating principle is the same as in Embodiment 2.

[0051] As shown in Figure 11, the ND blade 302 is positioned between the shafts 301b and 301c for the aperture blade guides, which are installed on the base member 301. By arranging the ND structure and aperture blade guide shafts in this way, space can be used effectively, making it possible to miniaturize the external dimensions of the light intensity adjustment device 300.

[0052] (Example 4) Figure 12 shows the internal configuration of an interchangeable lens 421 for an interchangeable lens camera, which is an imaging device equipped with the light intensity adjustment device 300 described in Example 3, and the camera body to which the interchangeable lens is attached. The light intensity adjustment device 300 may be the light intensity adjustment device 100 described in Example 1 or the light intensity adjustment device 200 described in Example 2.

[0053] The lens barrel of the interchangeable lens 421 houses a photographic optical system including a variable magnification lens 432, a light intensity adjustment device 300 (which includes an aperture, shutter, and ND filter, as described in the third embodiment), and a focusing lens 429.

[0054] The image sensor 425, composed of photoelectric conversion elements such as a CCD sensor or CMOS sensor, is located inside the camera body and outputs an electrical signal by photoelectric conversion of the subject image formed by the interchangeable lens 421. By changing the aperture of the light intensity adjustment device 300, controlling the timing of the movement of the shutter blade group 104, or moving the ND filter 302 forward and backward, the brightness of the subject image formed on the image sensor 425 (i.e., the amount of light reaching the image sensor 425) can be appropriately set.

[0055] The electrical signal output from the image sensor 425 is converted into a digital signal in the image processing circuit 426 and subjected to various image processing steps. This generates an image signal.

[0056] The user can perform zooming by rotating the zoom ring 431 to move the variable magnification lens 432. The controller 422 detects the contrast of the image signal and controls the focus motor 428 according to the contrast to move the focus lens 429 and perform autofocus. Alternatively, the controller 422 may control the focus motor 428 and move the focus lens 429 to perform autofocus based on the detection signal of a focus detection means using a phase difference detection method (not shown).

[0057] Furthermore, the controller 422 controls the aperture drive unit 102, shutter drive unit 110, and ND drive unit 206 of the light intensity adjustment device 300 based on the photometric value of a photometric means (not shown) or the image signal, thereby adjusting the amount of light. This makes it possible to create natural-looking bokeh and ghosting during shooting, and to record high-quality images.

[0058] Furthermore, the present invention is not limited to the interchangeable lens type camera described above, but can be broadly applied to optical devices such as digital cameras with integrated lenses, video cameras, and cameras built into smartphones.

[0059] The embodiments described above are merely representative examples, and when implementing the present invention, each embodiment may be used. Various transformations and modifications are possible.

[0060] Furthermore, the present invention is not limited to interchangeable lenses for cameras, but can be broadly applied to optical equipment such as digital cameras and video cameras with integrated lenses. The above-described light intensity adjustment device is preferably used in an imaging device that includes an image sensor that captures an image of light that has passed through the light intensity adjustment device. [Explanation of Symbols]

[0061] 100, 200, 300 light intensity adjustment device 101, 201, 301 Base members 105, 106, 107, 108 Shutter blades 109 Partition Member 117, 118 aperture blades

Claims

1. A base member having an opening through which light passes, A plurality of aperture blades move in a direction perpendicular to the optical axis of the light passing through the opening, advancing and retracting relative to the opening, and forming a smaller aperture than the opening; A first drive unit is positioned away from the aforementioned opening and moves the plurality of aperture blades back and forth, The base member is provided with a plurality of guide shafts that guide the aperture blades, A light intensity adjusting member that moves forward and backward relative to the opening, It comprises a second drive unit that rotates the magnet to operate the light intensity adjustment member, The light intensity adjustment member is positioned between the plurality of guide axes. A light intensity control device characterized by the following features.

2. The length from the rotating hole of the light intensity adjustment member, which is positioned between the plurality of guide shafts, to one of the guide shafts, The distance from the rotating hole of the light intensity adjustment member to the other vane guide shaft is equal. The light intensity adjustment device according to feature 1.

3. The light intensity adjusting member is a light-shielding vane, and the opening is opened or covered by the light-shielding vane moving forward and backward in the opening. The light intensity adjustment device according to feature 1.

4. The light intensity adjustment member is a light-reducing filter. The light intensity adjustment device according to feature 1.

5. A base member having an opening through which light passes, A plurality of aperture blades move in a direction perpendicular to the optical axis of the light passing through the opening, advancing and retracting relative to the opening, and forming a smaller aperture than the opening; A first drive unit is positioned away from the aforementioned opening and moves the plurality of aperture blades back and forth, The base member is provided with a plurality of guide shafts that guide the aperture blades, Multiple light-shielding vanes that move forward and backward relative to the opening, A second drive unit rotates a magnet to operate the plurality of light-shielding vanes, and comprises In the state in which the plurality of light-shielding vanes are retracted from the opening, A light intensity adjustment device characterized in that at least one of the plurality of light-shielding vanes is retracted in a plane perpendicular to the optical axis direction, on the side opposite to the side on which the guide axis is provided relative to the opening.

6. The plurality of light-shielding blades consist of four blades, and in the state where the plurality of light-shielding blades are retracted from the opening, Three of the aforementioned multiple light-shielding vanes are retracted in a plane along a direction perpendicular to the optical axis, on the side opposite to the side where the multiple guide axes are provided relative to the opening. The light intensity control device of the fifth feature.

7. An optical instrument comprising a light intensity adjustment device as described in any one of claims 1 to 6, and an image sensor for imaging light that has passed through the light intensity adjustment device.

Images