JP2024093749A - Light control devices and optical instruments - Google Patents

Abstract

A light amount adjustment device capable of reducing the difference in accuracy due to posture is provided.
[Solution] The lens comprises a base plate 50 having an opening, an aperture blade 10 that adjusts the amount of light passing through the opening, and a drive ring 20 that drives the aperture blade, wherein the aperture blade has a rotation center pin 11 which is inserted into a hole 51 provided in the base plate, and a drive ring is arranged on the side opposite to the side on which the rotation center pin of the aperture blade is provided, and has at least one of the rotation center pin support parts 52 which protrude around the hole toward the aperture blade and which protrudes toward the rotation center pin of the drive ring.
[Selected figure] Figure 2

Description

The present invention relates to a light amount adjustment device, also known as an aperture device, that is mounted on optical devices such as cameras and interchangeable lenses.

High precision and smooth operation are required for light quantity adjustment devices such as those described above. The drive ring rotates around a fixed aperture to rotate multiple aperture blades in the opening and closing directions, and the amount of light is adjusted by changing the size of the aperture (variable aperture) formed by the multiple aperture blades. This type of aperture device is also called an iris-type aperture device.

To reduce the curling of the blades, Patent Document 1 describes a configuration in which the drive ring and cover are each provided with protrusions that hold down the blades of the aperture blades.

JP 2020-140059 A

However, in the aperture device of Reference 1, if the engagement between the drive pin and the drive ring insertion hole is small, the aperture blades tend to tilt, and the accuracy changes depending on the position.

In order to solve the above problems, the light amount adjusting device of the present invention comprises:
A base plate having an opening;
an aperture blade for adjusting the amount of light passing through the aperture;
A drive ring that drives the aperture blades,
The aperture blade has a rotation center pin,
The rotation center pin is inserted into a hole provided in the main plate,
the drive ring is disposed on a surface of the aperture blade opposite to a surface on which the rotation center pin is provided,
The aperture is characterized in that it has at least one of a rotation center pin support portion protruding toward the diaphragm blade around the hole and a rotation center pin support portion protruding toward the rotation center pin of the drive ring.

According to the present invention, the movement of the aperture blades in the optical axis direction within the blade travel space can be reduced by using the rotation center pin support part on the base plate or drive ring. As a result, the accuracy difference due to the position can be reduced.

FIG. 2 is a perspective view of the aperture stop device according to the first embodiment. 1 is an exploded perspective view of a diaphragm device according to a first embodiment of the present invention; FIG. 4 is a perspective view of a drive ring in the aperture stop device of the first embodiment. FIG. 2 is a perspective view of an aperture blade in the aperture device of the first embodiment. FIG. 4 is a perspective view of a base plate in the aperture stop device of the first embodiment. FIG. 2 is a cross-sectional view of the aperture stop device according to the first embodiment. FIG. 4 is a diagram showing the range in which blades overlap in the aperture stop device of the first embodiment. FIG. 11 is a perspective view of a drive ring in the aperture stop device of the second embodiment. FIG. 11 is a cross-sectional view of a diaphragm apparatus according to a second embodiment. FIG. 11 is a diagram showing the overlapping range of blades in the aperture stop device of the second embodiment. FIG. 1 is a schematic diagram of an imaging apparatus equipped with an aperture device.

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

Example 1
Fig. 1 shows an assembled state of an iris diaphragm device 7 as a light amount adjusting device according to the first embodiment of the present invention. Fig. 2 shows an exploded view of the light amount adjusting device according to the first embodiment. Note that although a diaphragm device will be described here, a shutter device or a diaphragm device having a shutter function is also included in the light amount adjusting device according to the first embodiment of the present invention.

The aperture device 7 has an actuator 1, a pressing member 40, a drive ring 20, a number of aperture blades 10, a base plate 50, and a photointerrupter 3.

The actuator 1 is an electromagnetic actuator such as a stepping motor. A pinion gear 2 that rotates and drives a drive ring 20 is attached to the output shaft of the actuator 1. The actuator 1 and the pinion gear 2 form a drive source unit.

The photointerrupter 3 is used as a sensor for detecting the initial position of the drive ring 20. The actuator 1 is attached to the pressing member 40 by a screw 61.
When the diaphragm device 7 is mounted on an imaging device described later, the central axis 5 of the diaphragm device 7 coincides with the optical axis of the imaging device. In the following description, the direction parallel to the central axis 5 is referred to as the thrust direction. The pressing member 40, the drive ring 20, the multiple diaphragm blades 10, and the base plate 50 are stacked in this order in the thrust direction. That is, the drive ring 20 is disposed on the opposite side of the diaphragm blades 10 from the base plate 50, and the pressing member 40 is disposed on the opposite side of the diaphragm blades 10 and the drive ring 20 from the base plate 50. The direction and surface perpendicular to the thrust direction are referred to as the radial direction and radial surface, respectively.

The aperture blades 10 are arranged in a plurality in the circumferential direction of the fixed opening 54 formed in the base plate 50. In this embodiment 1, seven aperture blades 10 are used. Note that the number of aperture blades is not limited to seven, and may be any other number.

Figure 4 shows an enlarged view of one diaphragm blade 10. The diaphragm blade 10 is arranged so as to be nearly parallel to the radial plane, and has a flat blade portion having a light-blocking function, and a rotation center pin 11 and a cam pin 12 that protrude from the blade portion in opposite directions in the thrust direction. The positions of the rotation center pin 11 and the cam pin 12 in the radial plane are different from each other.

3 shows an enlarged view of the drive ring 20. The drive ring 20 has a light passage opening 24 at its center, and furthermore, the entire back surface serves as a blade support portion. In addition, radial support walls (rotation support portions) 22 extending toward the pressing member in the direction of the optical axis 5 are formed at a plurality of locations (seven locations in the first embodiment) in the circumferential direction of the drive ring 20. A radial protrusion 23 of the drive ring 20 fits into the inner peripheral portion of the pressing member 40, and is supported rotatably around the optical axis 5.
The drive ring 20 is formed with cam grooves 21 into which the cam pins 12 of the seven diaphragm blades 10 are inserted and engaged.

A gear portion 25 that meshes with the pinion gear 2 is formed on a portion of the outer periphery of the drive ring 20. The gear portion 25 is formed by extending radially outward from the radial protrusion 23.

Furthermore, at one circumferential location on the drive ring 20, a light-shielding protrusion 26 is provided that fits between the light-emitting portion and the light-receiving portion of the photointerrupter 3 to provide light shielding.

As shown in FIG. 2, the pressing member 40 is formed in a ring shape with a light passage opening 44 in its center, and is arranged to cover (press) the aperture blades 10 and drive ring 20 arranged between the pressing member 40 and the base plate 50, and is fixed to the base plate 50 with four screws 60.

Figure 5 shows the base plate 50, which is formed in a ring shape with a light passage opening 54 as a fixed opening in its center, and the ring-shaped portion is formed with multiple drive hole portions 51 (seven as many as the aperture blades 10) into which the rotation center pins 11 of the multiple aperture blades 10 each engage.

In addition, around the drive hole there is a rotation center pin support portion 52 to reduce the amount of change in the engagement caused by the rotation center pin 11 coming out due to its position.

Figure 6 shows a cross-sectional view of this embodiment 1, in which the aperture blade 10 travels through the blade travel space 81 formed between the drive ring 20 and the base plate 50. At this time, the drive ring 20 is supported so as to be sandwiched between the base plate 50 and the pressing member 40, and the space necessary for the aperture blade 10 to operate is provided.

Normally, when open, the aperture blades 10 overlap each other by three blades in the direction of the optical axis 5 of the travel space 81, and when closed, the overlap is two blades.

In addition, the movement of the rotation center pin 11 in the thrust direction within the blade running space 81 is further restricted by the rotation center pin support portion 52.

When open, the aperture blades overlap only one another in the direction of the optical axis 5 at the drive pin support portion 52, whereas in the past there were two.

Figure 7 shows the overlapping range of the blades in the aperture device of Example 1, where multiple aperture blades 10 overlap in the overlapping range 70, with only one blade passing over the drive pin support portion 52, reducing the amount of overlap of the blades.

The drive pin support 52 makes it difficult for the blades of the rotation center pin 11 of the aperture blade 10 to tilt without interfering with the operation of the aperture blade 10 as shown in Figures 6 and 7, which reduces the interweaving of the blades when the blades are stopped down and reduces changes in accuracy due to differences in posture.

In this embodiment, "supporting (or holding)" the aperture blade 10 means providing the necessary play for smooth rotation of the aperture blade 10 while restricting the movement of the aperture blade 10 so that it does not rattle or fall off any further. In other words, it does not mean holding it down so that there is no play in any direction other than the rotation direction (thrust direction).

In the aperture device 7 configured as described above, when the actuator 1 operates and the pinion gear 2 rotates, the drive ring 20 rotates (in the circumferential direction) around the central axis 5 relative to the base plate 50 and the pressing member 40. The drive ring 20 transmits the driving force from the actuator 1 to the seven aperture blades 10 via the cam pins 12. As a result, each aperture blade 10 rotates around the rotation center pin 11 as the cam pins 12 move along the cam groove portions 51. By controlling the rotation position of the drive ring 20 by the actuator 1, the rotation positions of the multiple aperture blades 10, that is, the size (diameter) of the aperture opening (variable aperture) formed by the blade portions of the multiple aperture blades 10, is controlled. The amount of light passing through the light passing openings 44, 24, 54 can be changed (adjusted) according to the aperture opening diameter.

The initial rotational position of the drive ring 20, which is necessary to control the rotational position of the drive ring 20, can be detected by detecting a signal indicating that the light-shielding protrusion 26 of the drive ring 20 has entered between the light-emitting and light-receiving parts of the photointerrupter 3 and blocked the light from the light-emitting part.

Example 2
In the second embodiment, the main plate 50 does not have a drive pin support portion 52, while a drive ring 120 has a drive pin support portion 122 formed around the entire circumference as shown in FIG.

Figure 9 shows a cross-sectional view of this embodiment 2, where the blade travel space 181 is determined by the space created by the drive ring 120 and the base plate 50. At this time, the drive ring 120 is supported so as to be sandwiched between the base plate 50 and the pressing member 40, and the space necessary for the aperture blade 10 to operate is provided.

In addition, the movement of the rotation center pin 11 in the direction of the optical axis 5 within the blade running space 181 is further restricted by the drive pin support portion 122.

Figure 10 shows the overlapping range of the blades in the aperture device of Example 2, where multiple aperture blades 10 overlap in overlapping range 170, with only one blade passing over the drive pin support portion 122.

The drive pin support 122 makes it difficult to reduce the engagement amount of the rotation center pin 11 of the aperture blade 10 without interfering with the operation of the aperture blade 10 as shown in Figures 9 and 10, and can reduce changes in accuracy due to differences in posture. By providing at least one of the rotation center support parts of Example 1 and Example 2, changes in accuracy due to differences in posture can be reduced, and both may be provided.

Example 3
FIG. 11 shows an interchangeable lens 221 for a single-lens reflex camera, serving as an imaging device equipped with the diaphragm 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 photographic optical system including a variable magnification lens 232, the aperture device 100 of embodiment 1 that narrows the optical path, 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 diaphragm 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 stepping motor (actuator) 1 of the aperture 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 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 variations are possible when implementing the present invention.

REFERENCE SIGNS LIST 1 actuator 2 pinion gear 3 photointerrupter 10 aperture blade 20 drive ring 40 pressing member 50 base plate 52 rotation center pin support portion

Claims (5)

A base plate having an opening;
an aperture blade for adjusting the amount of light passing through the aperture;
A drive ring that drives the aperture blades,
The aperture blade has a rotation center pin,
The rotation center pin is inserted into a hole provided in the main plate,
the drive ring is disposed on a surface of the aperture blade opposite to a surface on which the rotation center pin is provided,
a rotation center pin support portion protruding toward the aperture blade around the hole and/or a rotation center pin support portion protruding toward the rotation center pin of the drive ring. The light amount adjustment device according to claim 1, characterized in that only one of the aperture blades overlaps in the optical axis direction at the rotation center pin support portion. The light amount adjusting device according to claim 1, characterized in that the rotation center pin support part is provided on the drive ring and is arranged so as to overlap the hole and its periphery. The light amount adjustment device according to claim 3, characterized in that the rotation center pin support portion is convex and provided on the side of the drive ring on which the aperture blade slides. 5. 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.