JP2024108251A - Light quantity control device and optical equipment - Google Patents

Abstract

To solve a problem in which a tilt of an ND filter or a blade member during rotation of the ND filter, in particular, around a rotation axis is great, and by the tilt, the ND filter or the blade member might deform.SOLUTION: An amount-of-light adjustment device of the present invention comprises: a base plate member 1 that has an opening part transmitting light provided; a cover member 2 that is fixed to the base plate member 1; an amount-of-light adjustment member 3 that moves with respect to the opening part; and an actuator that actuates the amount-of-light adjustment member 3. The base plate member 1 and the cover member 2 have a rail group that is curved outward on an amount-of-light adjustment member 3 side, and forms a space where the amount-of-light adjustment member 3 moves. Of the space the rail group forms, a thickness of a space formed on an actuation shaft side of the actuator relative to the opening part and formed by a first rail pair 1d/2d is thinner than that of a space formed on a tip end side of the amount-of-light adjustment member 3 and formed by a second rail pair 1f/2f.SELECTED DRAWING: Figure 9

Description

The present invention relates to a light intensity adjustment device used in optical imaging devices such as digital still cameras, and to optical devices equipped with a light intensity adjustment device.

ND filters are known as one of the exposure control methods used in digital still cameras, video cameras, and digital cameras. ND filters adjust the amount of light taken in by forming a vapor-deposited film on a substrate, and the substrate is generally made of synthetic resin.

There are two main types of ND filter configurations known for incorporation into cameras. One is a configuration in which an ND filter is provided on a blade member having an aperture smaller than the exposure aperture, covering the aperture. The other is a configuration in which no blade member is used, and the exposure aperture is covered by an ND filter alone. In either case, the ND filter and blade member are stored in a blade chamber formed by a base member and a cover member, or a sheet member. Patent Document 1 discloses a blade member provided with an ND filter as an optical filter.

JP 2017-40720 A

Patent Document 1 describes a blade chamber that houses an ND filter or a blade member, the thickness of which is constant throughout. Also, to prevent non-operation, the blade chamber is set to be somewhat large, and as a result, when the ND filter rotates, the ND filter or the blade member becomes significantly tilted, particularly around the rotation axis, and this tilting can cause deformation of the ND filter or the blade member.

In order to solve the above problems, the light amount adjusting device of the present invention comprises:
A base plate member having an opening for passing light therethrough;
A cover member fixed to the base plate member;
a light amount adjusting member that moves relative to the opening;
a drive unit that drives the light amount adjustment member,
the base plate member and the cover member have a rail group that is convex toward the light amount adjustment member and forms a space in which the light amount adjustment member moves,
The thickness of the space formed by the group of rails, which is formed by a first pair of rails closer to the drive shaft of the drive unit than the opening, is thinner than the thickness of the space formed by a second pair of rails formed on the tip side of the light amount adjustment member.

According to the present invention, it is possible to prevent the ND filter or the blade member from tilting around the rotation axis, making it difficult for the ND filter or the blade member to deform.

FIG. 1 is an exploded perspective view of a light amount adjustment device according to a first embodiment of the present invention; FIG. 1 is an explanatory diagram of a base plate member of a light amount adjustment device according to a first embodiment of the present invention; FIG. 1 is an explanatory diagram of a cover member of a light amount adjustment device according to a first embodiment of the present invention; FIG. 1 is an explanatory diagram of a blade member of a light amount adjustment device according to a first embodiment of the present invention; FIG. 1 is an explanatory diagram of a driving unit of a light amount adjustment device according to a first embodiment of the present invention; FIG. 1 is an explanatory diagram of a light amount adjustment device according to a first embodiment of the present invention in an open state; FIG. 1 is an explanatory diagram of a closed state of a light amount adjustment device according to a first embodiment of the present invention; FIG. 1 is a cross-sectional view of a light amount adjustment device according to a first embodiment of the present invention; 1 is an explanatory diagram of a cross section AA and a cross section BB of a light amount adjustment device according to a first embodiment of the present invention; FIG. 11 is an explanatory diagram of a blade member of a light amount adjustment device according to a second embodiment of the present invention; FIG. 1 is an explanatory diagram of an optical device equipped with a light amount adjustment device according to the present invention;

The following describes in detail an embodiment of the present invention with reference to the attached drawings.

First Embodiment
1 is an exploded perspective view of a light amount adjusting device according to a first embodiment of the present invention. The light amount adjusting device is used as a light amount adjusting device for an imaging device such as a digital camera, and is mainly composed of a base plate member 1, a cover member 2, an ND filter 3, a blade member 4, a drive unit 5, and a drive unit cover 6.

Figure 2 is an explanatory diagram of the base plate member 1. The base plate member 1 has an opening 1a that is concentric with the optical axis of the light passing through it. The base plate member 1 also has a sector-shaped opening 1b that is open over the range of movement of the ND filter 3, preventing the ND filter 3 from coming into contact with the base plate member 1 and causing damage to the ND filter 3. The base plate member 1 also has a rotating shaft 1c, and the shaft hole 4a provided in the blade member 4 fits into this rotating shaft 1c. The base plate member 1 also has rails 1d, 1e, and 1f that are convex toward the blade member 4, and together with the rails of the cover member 2 described later, form a blade chamber (space) that stores the ND filter 3 and the blade member 4. The base plate member 1 also has protrusions 1g and 1h, each of which acts as a mechanical stopper for the blade member 4.

Figure 3 is an explanatory diagram of the cover member 2. The cover member 2 has an opening 2a concentric with the optical axis, similar to the base plate member 1, and a fan-shaped opening 2b, similar to the base plate member 1. The opening 2b is open over the movement range of the ND filter 3, and prevents the ND filter 3 from coming into contact with the cover member 2 and scratching the ND filter 3. The cover member 2 also has an insertion portion 2c, through which the rotating shaft 1c of the base plate member 1 is inserted. Furthermore, the cover member 2 has rails 2d, 2e, and 2f that are convex toward the blade member 4, and are provided at approximately the same position as the rails 1d, 1e, and 1f of the base plate member 1. The ND filter 3 and the blade member 4 are housed in a blade chamber formed by the rails 1d, 1e, and 1f of the base plate member 1 and the rails 2d, 2e, and 2f of the cover member 2. Of these rail groups, rails 1d and 2d form a pair, and rails 1e and 2e, and rails 1f and 2f also form rail pairs, with each pair forming a space in which the blade member 4 runs. Rails 1d and 2d are provided closer to the drive unit 5 than the opening 2b. Rails 1f and 2f are provided on the tip side of the blade member 4. Rails 1f and 2f are provided closer to the opening 2b than the drive shaft of the drive unit 5.

Figure 4 is an explanatory diagram of the blade member 4. The blade member 4 has an axial hole 4a into which the pivot shaft 1c of the base plate 1 fits. In addition, a long hole 4b is provided near the axial hole 4a, into which a protrusion 5a' (drive shaft) of the drive unit 5 fits. The ND filter 3 and the blade member 4 are attached by adhesion, which involves applying adhesive to the recess 4c of the blade member 4 and attaching the ND filter 3 from above. In this embodiment 1, there are two recesses 4c, and therefore two adhesion points, but the number of recesses 4c and the number of adhesion points may be only one or more than two.

Figure 5 is an explanatory diagram of the drive unit 5. The drive unit 5 is a mechanism for opening and closing the ND filter 3 and the blade member 4, and is, for example, an electric actuator such as a moving magnet actuator. The moving magnet actuator has, for example, an arm part 5a in which resin is insert-molded onto a rotor magnet magnetized with two poles (N pole and S pole) on the outer periphery of a permanent magnet, and a yoke 5b arranged on the outer periphery of the arm part 5a, and is an actuator that rotates the arm part 5a by utilizing the attractive and repulsive forces generated between the arm part 5a and the yoke 5b when electricity is applied to the coil 5c. The arm part 5a also has a protrusion 5a' that fits into a long hole 4b provided in the blade member 4.

Figure 6 is an explanatory diagram of the open state of the ND filter 3 and the blade member 4 in this embodiment 1. The flat surface 4d of the blade member 4 is abutted against the protrusion 1g, and the ND filter 3 and the blade member 4 are in a retracted state so as not to cover the opening 1a.

Figure 7 is an explanatory diagram of the ND filter 3 and the blade member 4 in the closed state in this embodiment 1. The flat surface 4e of the blade member 4 is abutted against the protrusion 1h, and the ND filter 3 and the blade member 4 cover the opening 1a.

In the first embodiment, the ND filter 3 and the blade member 4 rotate to open and close the opening 1a, but the ND filter 3 and the blade member 4 may move in parallel to open and close the opening 1a. Also, any light amount adjustment member other than the ND filter attached to the blade member may be used as long as it is a member that adjusts the amount of light.

Figure 8 is a cross-sectional explanatory diagram of the state in which the various parts in this embodiment 1 are assembled into a unit and in a closed state. The area around the rotation axis 1c of the base plate member 1 is cross-section A-A, and the opposite side (tip side) is cross-section B-B.

Figure 9a is an explanatory diagram of the A-A cross section in this embodiment 1. Around the rotation axis 1c, only the blade member 4 is located in the blade chamber Gd formed by rails 1d and 2d. Around the opening 2a, the ND filter 3 and the blade member 4 are located in the blade chamber Ge formed by rails 1e and 2e. The blade chamber Ge is set to be slightly wider since the adhesive parts of the ND filter 3 and the blade member 4 are located there.

Figure 10b is an explanatory diagram of the B-B cross section in this embodiment 1. The ND filter 3 and the blade member 4 are located in the blade chamber Gf formed by the rail 1f and the rail 2f. The ND filter 3 and the blade member 4 at the B-B cross section are free ends. In this embodiment 1, the blade member 4 abuts against the rail 1f, and the ND filter 3 abuts against the rail 2f, but the reverse configuration is also possible, and it is also possible for only either the ND filter 3 or the blade member 4 to abut.

The first embodiment is characterized in that the end face of rail 2d protrudes toward the ND filter 3 and blade member 4 more than the end face of rail 2f. This configuration suppresses tilt of the blade member 4 around the rotation axis 1c, and prevents deformation. It is also possible to configure the end face of rail 1d to protrude toward the ND filter 3 and blade member 4 more than the end face of rail 1f of the base member 1, and further to configure both the end face of rail 1d and the end face of rail 2d to protrude from the end faces of rails 1f and 2f.

In this embodiment 1, the thickness of the blade chamber Gd is smaller than the thickness of the blade chamber Gf. With this configuration, when the blade member 4 collides with the protrusion 1g or protrusion 1h of the base plate member 1, the thickness of the blade chamber Gd is kept small, which makes it possible to prevent the blade member 4 from tilting and to prevent deformation of the shaft hole 4a.

In the first embodiment, with regard to the relationship between the blade chambers, it is preferable that the thickness of the blade chamber Ge is greater than the thickness of the blade chamber Gf. The ND filter 3 and the blade member 4 are fixed by adhesion, and this adhesion point is located inside the blade chamber Ge. In other words, the adhered portion of the ND filter 3 moves into the blade chamber Ge.
At the adhesive portion, the thickness of the adhesive is added to the thickness of the ND filter 3 and the blade member 4; however, by making the thickness of the blade chamber Ge large, the ND filter 3 and the blade member 4 can slide smoothly.

Second Embodiment
10 shows the blade member 4 of the light amount adjustment device of the second embodiment. By providing three recesses 4c and dispersing the load on the adhesive portion during rotation of the ND filter 3 and the blade member 4, the risk of damage to the adhesive portion or the ND filter 3 can be reduced.

Third Embodiment
FIG. 11 shows an interchangeable lens 221 for a single-lens reflex camera, serving as an image capture device equipped with the light amount adjustment device described in the first and second embodiments, and the internal configuration of a camera body to which the interchangeable lens is attached.

The lens barrel of the interchangeable lens 221 houses a photographing optical system including a variable magnification lens 232, the light amount adjustment device 100 of embodiment 1, and a focus lens 229.

The image sensor 225, which is composed of photoelectric conversion elements such as a CCD sensor or a CMOS sensor, is disposed in the camera body and photoelectrically converts the subject image formed by the interchangeable lens 221 to output an electrical signal. By changing the aperture of the light amount adjustment device 100 or by moving an ND filter (not shown) forward or backward, the brightness of the subject image formed on the image sensor 225 (i.e., the amount of light reaching the image sensor 225) can be appropriately set.

The electrical signal output from the image sensor 225 is converted to a digital signal in the image processing circuit 226 and undergoes various image processing. This generates an image signal.

By rotating the zoom ring 231, the user can move the variable magnification lens 232 to change the magnification (zooming). The controller 222 detects the contrast of the image signal, controls the focus motor 228 in accordance with the contrast, and moves the focus lens 229 to perform autofocus. Alternatively, the controller 222 may control the focus motor 228 and move the focus lens 229 to perform autofocus based on a detection signal from a focus detection means that uses a phase difference detection method (not shown).

Furthermore, the controller 222 controls the actuator (drive unit) of the light amount adjustment device 100 based on the photometric value of a photometric means (not shown) or an image signal to adjust the amount of light. This makes it possible to make the blur and ghosting that occurs during shooting appear natural, allowing high-quality images to be recorded.

The present invention is not limited to the single-lens reflex camera described above, but can also be widely applied to optical devices such as digital cameras with integrated lenses and video cameras.

The above-described embodiments are merely representative examples, and various modifications and alterations are possible when implementing the present invention.

1 Base plate member
1a Opening 1d, 1e, 1f Rail 2 Cover member
2a Opening 2d, 2e, 2f Rail 3 ND filter
4 Blade member
5 Drive unit 6 Drive unit cover

Claims (6)

A base plate member having an opening for passing light therethrough;
A cover member fixed to the base plate member;
a light amount adjusting member that moves relative to the opening;
a drive unit that drives the light amount adjustment member,
the base plate member and the cover member have a rail group that is convex toward the light amount adjustment member and forms a space in which the light amount adjustment member moves,
A light intensity adjusting device characterized in that, among the spaces formed by the group of rails, the thickness of the space formed by a first pair of rails on the drive shaft side of the drive unit relative to the opening is thinner than the thickness of the space formed by a second pair of rails formed on the tip side of the light intensity adjusting member. The light amount adjusting device according to claim 1, characterized in that the thickness of the space formed by the rail group, which is formed by the third rail pair on the opening side of the drive shaft of the drive unit, is thicker than the thickness of the space formed by the second rail pair. The light amount adjustment device according to claim 1, characterized in that the first pair of rails protrudes further toward the light amount adjustment member than the second pair of rails. The light amount adjustment device according to claim 2, characterized in that the portion of the light amount adjustment member to which the ND filter is attached moves in the space formed by the third rail pair. The light amount adjustment device according to claim 4, characterized in that the light amount adjustment member is a blade member to which the ND filter is attached at three points. 6. An optical device comprising: the light amount adjusting device according to claim 1; and an imaging element that captures an image of light that has passed through the light amount adjusting device.

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