Ocular fundus imaging apparatus

Abstract

To acquire a better photographed image.SOLUTION: An ocular fundus imaging apparatus includes an imaging optical system and acquires an ocular fundus image. The imaging optical system includes: a slit formation part for forming a slit opening through a slit plate and a mask when the slit plate and the mask for shielding an opening formed on the slit plate partially or selectively are arranged overlapped along an optical axis; a driving part for rotating the slit formation part, which can reverse a rotation direction of the slit formation part; a switching mechanism for switching area ratios between a shielding part and the slit opening formed in the slit formation part by changing positional relationships between the slit plate and the mask according to a normal or reverse rotation direction; and a fixing mechanism for fixing positional relationships between the slit plate and the mask that have been changed by the switching mechanism in conjunction with the rotation of the slit formation part.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to a fundus imaging device for obtaining a front image of a fundus. [Background technology]

[0002] Fundus photographing devices that photograph a front image of the fundus of a subject's eye are widely used in the field of ophthalmology. As a fundus photographing device, a device is known that scans a slit-shaped illumination light on the fundus by driving a slit arranged in an optical path, and sequentially projects an image of the illuminated slit-shaped area on the fundus onto a two-dimensional imaging plane according to the scanning, thereby obtaining a front image of the fundus. In this type of fundus photographing device, in order to enable good color photography, fluorescent photography, etc., a device has been proposed that has a slit forming section in which a slit plate and a mask are arranged overlapping along the optical axis, and changes the positional relationship between the slit plate and the mask depending on the forward / reverse rotation direction of the slit forming section to switch the area ratio of the light-shielding section and the slit opening of the slit forming section (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-42896 A Summary of the Invention [Problem to be solved by the invention]

[0004] Further improvements are desired in the above fundus photography device. For example, it has been found that there are cases where the rotation of the slit forming part becomes uneven (the rotation speed, acceleration, etc. becomes unstable), in which case the positional relationship between the slit plate and the mask becomes unstable, and the area ratio between the light blocking part and the slit opening changes during the rotation, resulting in a failure to obtain a photographed image with good brightness.

[0005] In view of the conventional technology, the present disclosure has as its technical object to provide a fundus imaging device capable of obtaining better captured images. [Means for solving the problem]

[0006] (1) A fundus imaging device according to a first aspect of the present disclosure is a fundus imaging device that includes an imaging optical system including an illumination optical system that illuminates the fundus of a subject's eye with illumination light, and a light receiving optical system including an image sensor that receives return light of the illumination light from the fundus, and obtains a fundus image that is a front image of the fundus based on a light receiving signal from the image sensor, wherein the imaging optical system includes a slit forming section that includes a slit opening and a light blocking section for forming a slit-shaped imaging area on the fundus, and a slit plate and a mask that partially or selectively blocks the opening formed in the slit plate are overlapped along an optical axis, thereby obtaining a fundus image through the slit plate and the mask. The optical system is characterized in that it comprises a slit forming section that forms the slit opening, a drive section that rotates the slit forming section in a direction in which the long side of the slit opening crosses at least one of the light beams of the illumination light and the return light, the drive section being capable of reversing the rotation direction of the slit forming section, a switching mechanism that switches the area ratio between the light-shielding section and the slit opening in the slit forming section by changing the positional relationship between the slit plate and the mask depending on whether the rotation direction is positive or negative, and a fixing mechanism that fixes the positional relationship between the slit plate and the mask changed by the switching mechanism in conjunction with the rotation of the slit forming section. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an external configuration of a fundus imaging apparatus. [Diagram 2] FIG. 2 is a diagram showing an optical system housed in the photographing unit. [Diagram 3] FIG. 2 is a block diagram showing a control system of the fundus imaging apparatus. [Figure 4] FIG. 13 is a diagram showing an optical chopper that can be used as a scanning unit. [Diagram 5] FIG. 4 is a diagram showing a slit plate which is a part of the slit forming portion. [Figure 6] FIG. 13 is a diagram showing a mask that is a part of a slit forming portion. [Figure 7] FIG. 7 is a diagram for explaining the pin holding portion by the mask, and is an enlarged view of the AA cross section in FIG. 6. [Figure 8] FIG. 6 is a diagram for explaining a connecting hole, and is an enlarged view of the vicinity of the connecting hole in FIG. 5. [Figure 9] FIG. 13 is a diagram showing the positional relationship between the connecting hole and the pin when the rotation of the slit plate is stopped. [Figure 10] This shows the state in which the slit plate connected to the mask is rotated clockwise. [Figure 11] This shows the state in which the slit plate connected to the mask is rotated counterclockwise. [Figure 12] 13 is a diagram illustrating a fixing mechanism in which a connecting hole and a pin are provided as one set. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [overview] Hereinafter, one exemplary embodiment will be described with reference to the drawings. Note that the items grouped in <> below can be used independently or in conjunction with each other.

[0009] For example, a fundus imaging device (e.g., imaging device 1) includes an imaging optical system (e.g., imaging optical system 10). For example, the imaging optical system includes an irradiation optical system (e.g., irradiation optical system 10a) and a light receiving optical system (e.g., light receiving optical system 10b). For example, the imaging optical system includes a slit forming unit (e.g., slit forming units 15a, 15b), a driving unit (e.g., driving unit 15c), a switching mechanism (e.g., switching mechanism 155), and a fixing mechanism (e.g., fixing mechanism 157).

[0010] <Irradiation optical system, light receiving optical system> For example, the illumination optical system illuminates the fundus of the subject's eye with illumination light. For example, the light receiving optical system has at least an image sensor. Also, for example, the light receiving optical system receives return light of the illumination light from the fundus by the image sensor. For example, the fundus imaging device obtains a fundus image, which is a front image of the fundus, based on a light receiving signal from the image sensor.

[0011] For example, the image sensor receives return light from the illumination area. In this embodiment, the fundus reflection light to the illumination light and the fluorescence from the fundus are collectively referred to as "return light." In this embodiment, the image sensor may be a two-dimensional light receiving element disposed at a fundus conjugate position.

[0012] <Slit forming section> For example, the slit forming unit includes a slit opening (e.g., slit openings 163, 165) for forming a slit-shaped photographing area on the fundus and a light blocking unit (e.g., light blocking unit 182). For example, the slit forming unit forms a slit opening via a slit plate (e.g., slit plate 160) and a mask (e.g., mask 180) for partially or selectively blocking the opening formed in the slit plate, by arranging them in layers along the optical axis. For example, the slit forming unit may be composed of an optical chopper (e.g., optical chopper 150).

[0013] For example, the slit plate may have two types of slit openings: a first slit opening (e.g., slit opening 165) having a narrower opening width, and a second slit opening (e.g., slit opening 163) having a wider opening width than the first slit opening. In this case, the mask may have a slit opening (e.g., slit opening 183) that selectively blocks light from either the first slit opening or the second slit opening and exposes the other. For example, the first slit opening having a narrower opening width is used in a normal color imaging mode, and the second slit opening having a wider opening width is used in a fluorescent imaging mode.

[0014] Also, for example, the slit plate may have one type of slit opening, and the mask may be configured to partially block light within the width of this slit opening.

[0015] <Drive unit> For example, the drive unit rotates the slit forming unit in a direction in which the long side of the slit opening intersects at least one of the luminous fluxes of the illumination light and the return light. For example, the drive unit is capable of reversing the rotation direction of the slit forming unit.

[0016] <Switching mechanism> For example, the switching mechanism changes the positional relationship between the slit plate and the mask depending on the forward or reverse rotation direction of the slit forming part, thereby switching the area ratio between the light blocking part and the slit opening in the slit forming part. For example, the switching mechanism mechanically switches the area ratio between the light blocking part and the slit opening in the slit forming part.

[0017] For example, the switching mechanism may be a delay generating mechanism (in other words, a deviation generating mechanism). In this case, for example, the delay generating mechanism may delay the power transmission from the drive unit to the slit plate and the mask by a predetermined amount of movement between the slit plate and the mask when the rotation direction of the slit forming unit is switched between forward and reverse. For example, when the slit forming unit is rotated in the forward direction, one of the slit plate and the mask is shifted in the reverse direction by a predetermined amount of movement with respect to the other. On the other hand, when the slit forming unit is rotated in the reverse direction, one of the slit plate and the mask is shifted in the forward direction by a predetermined amount of movement with respect to the other. This delay generating mechanism does not require an extra actuator for switching, and by utilizing the drive unit that rotates the slit forming unit, the area ratio between the slit opening and the light blocking unit can be switched with a simple configuration in which the positional relationship between the slit plate and the mask that are arranged overlapping along the optical axis is simply switched.

[0018] For example, the delay generating mechanism may be configured to include a pin (e.g., pin 187) provided on a first rotor of one of the slit plate and the mask, and a connecting hole (e.g., connecting hole 167) provided on a second rotor of the other of the slit plate and the mask, into which the pin is inserted. In this case, for example, the connecting hole may have a length that allows the pin to move in accordance with a predetermined amount of movement associated with the forward and reverse rotation directions of the slit forming part. For example, the length of the connecting hole through which the pin can move is set to the circumferential length of the rotor. The delay generating mechanism may be configured such that the driving unit rotates one of the first rotor and the second rotor, and power from the driving unit is transmitted to the other rotor through the connection between the pin and the connecting hole.

[0019] The delay generating mechanism can be rephrased as a deviation generating mechanism for deviating the power transmission from the drive unit by a predetermined amount of movement between the slit plate and the mask.

[0020] <Fixing mechanism> For example, the fixing mechanism fixes the positional relationship between the slit plate and the mask changed by the switching mechanism in conjunction with the rotation of the slit forming part. This allows a captured image with good brightness to be obtained without changing the area of ​​the slit opening during the rotation even if rotational unevenness (unstable rotation speed, acceleration, etc.) occurs during the rotation of the slit forming part. For example, the fixing mechanism may fix the positional relationship between the slit plate and the mask in conjunction with the forward and reverse rotation of the slit forming part.

[0021] For example, in the case where the switching mechanism is a delay generating mechanism, and one of the first rotating bodies, the slit plate and the mask, has a pin, and the other second rotating body has a connecting hole into which the pin is inserted, the fixing mechanism may have a pin holding part (e.g., holding part 190) that movably holds the pin, and a fixing hole (e.g., fixing hole 168) provided in the connecting hole, and may be configured to utilize the centrifugal force accompanying the rotation of the first rotating body. For example, the pin holding part holds the pin movably in the radial direction relative to the center of rotation of the first rotating body. For example, the fixing hole is formed so that the pin held in the pin holding part can move radially outward in response to a predetermined amount of movement associated with the forward and reverse rotation directions of the slit forming part. For example, the fixing hole may have a shape that fixes both the forward and reverse rotations of the second rotating body relative to the pin when the pin enters the fixing hole. In this case, the fixing mechanism may be configured so that the positional relationship between the slit plate and the mask is fixed by moving the pin to the fixing hole by the centrifugal force associated with the rotation of the first rotating body.

[0022] For example, the fixing hole may have a first fixing hole in which the pin is moved radially outward by a predetermined amount when the slit forming part is rotated in the forward direction, and a second fixing hole in which the pin is moved radially outward by a predetermined amount when the slit forming part is rotated in the reverse direction. Also, for example, the fixing hole may have a catch that prevents the second rotating body having the connecting hole from rotating in the reverse direction to the rotation direction when the pin enters the fixing hole by centrifugal force.

[0023] For example, when the fixing mechanism has the pin holding portion, it may further include a pulling force applying portion (e.g., spring 189) that applies a pulling force that moves the pin toward the rotation center of the first rotor. In this case, it is preferable that the pulling force is set to be smaller than the centrifugal force acting on the pin as the first rotor rotates. This allows the pin to be more reliably positioned away from the fixing hole toward the center of the connecting hole when the rotation stops, allowing smooth switching.

[0024] In addition, if no mechanism for applying a pulling force is provided, the pin may be configured to come out of the fixing hole when the rotor stops due to gravity acting on the pin. In this case, for example, by stopping the rotation of the rotor with the pin positioned vertically above the center of rotation of the rotor, the connecting hole is positioned downward, and the pin comes out of the fixing hole and moves to the connecting hole due to the action of gravity.

[0025] For example, when a plurality of sets of connecting holes into which pins are inserted and fixing mechanisms having fixing holes through which the pins are moved are provided, their centers of gravity may coincide with the rotation centers of the respective rotating bodies. In this case, the rotating bodies rotate in a more balanced manner than when there is only one set of connecting holes and fixing mechanisms. Note that "coincidence" also includes "approximate coincidence." The degree of the approximate coincidence may be determined based on the relationship of the required functions.

[0026] [Example] An example of this embodiment will be described with reference to the drawings. Fig. 1 is a diagram showing the external configuration of a fundus photographing device according to the example. Fig. 2 is a diagram showing an optical system housed in a photographing unit of the example. Fig. 3 is a block diagram showing a control system of the device according to the example.

[0027] <Appearance of the device> The external configuration of the photographing device 1 will be described with reference to Fig. 1. The photographing device 1 has a photographing unit 3. The photographing unit 3 mainly includes an optical system shown in Fig. 2. The photographing device 1 has a base 7, a drive unit 8, a face support unit 9, etc., and uses these to adjust the positional relationship between the subject's eye E and the photographing unit 3.

[0028] The driving unit 8 can move the housing 6 in which the photographing unit 3 is disposed in the left-right direction (X direction) and the front-back direction (Z direction, also called the working distance direction) relative to the base 7. The driving unit 8 also moves the photographing unit 3 in three-dimensional directions relative to the subject's eye E on the housing 6. The driving unit 8 has an actuator for moving the housing 6 or the photographing unit 3 in each of the predetermined movable directions, and is driven based on a control signal from the control unit 100. The face support unit 9 supports the subject's face. The face support unit 9 is fixed to the base 7.

[0029] The photographing device 1 further includes a monitor 120. The monitor 120 displays an observation image of the fundus, a photographed image of the fundus, an observation image of the anterior segment, and the like.

[0030] <Optical system> The optical system of the photographing device 1 will be described with reference to Fig. 2. The photographing device 1 has a photographing optical system (fundus photographing optical system) 10 and an anterior eye observation optical system 40. These optical systems are provided in the photographing unit 3. In Fig. 2, the position conjugate with the pupil of the subject's eye is indicated by a "△" on the photographing optical axis, and the fundus conjugate position is indicated by an "X" on the photographing optical axis.

[0031] The photographing optical system 10 includes an irradiation optical system 10a and a light receiving optical system 10b. In this embodiment, the irradiation optical system 10a includes a light source unit 11, a lens 13, a slit forming unit 15a, lenses 17a and 17b, a mirror 18, a mirror with a hole 20, and an objective lens 22.

[0032] The light receiving optical system 10b has an objective lens 22, a mirror with a hole 20, lenses 25a and 25b, a slit forming section 15b, and an image sensor 28. The mirror with a hole 20 is an optical path coupling section that couples the optical paths of the irradiation optical system 10a and the light receiving optical system 10b. The mirror with a hole 20 reflects illumination light from a light source to the subject's eye E, and transmits a portion of the fundus reflected light from the subject's eye E that passes through an opening to the image sensor 28.

[0033] In this embodiment, the light source unit 11 has a plurality of types of light sources with different wavelength bands. For example, the light source unit 11 has visible light sources 11a and 11b and infrared light sources 11c and 11d. The two light sources with the same wavelength band are arranged away from the imaging optical axis L on the pupil conjugate plane. The two light sources are arranged along the X direction, which is the scanning direction in FIG. 2, and are arranged axially symmetrically with respect to the imaging optical axis L. As shown in FIG. 2, the outer peripheral shape of the two light sources may be a rectangle whose length in a direction intersecting the scanning direction is longer than that in the scanning direction.

[0034] In FIG. 2, two visible light sources are shown, denoted by reference numerals 11a and 11b, but each of the light sources 11a and 11b includes a plurality of visible light sources for each wavelength. For example, light sources corresponding to the three colors of R (red), G (green), and B (blue) may be included in each of the visible light sources 11a and 11b. As a result, in this embodiment, any of the three colors of R (red), G (green), and B (blue) may be irradiated in any combination. For example, when a color fundus image is to be photographed, the three colors of R (red), G (green), and B (blue) may be irradiated. Also, when performing autofluorescence photography, which is a type of fluorescence photography, light of the wavelength of G (green) or B (blue) may be irradiated.

[0035] Light from the light source 11 passes through the lens 13 and is irradiated onto the slit forming portion 15a. In this embodiment, the slit forming portion 15a has a light transmitting portion (aperture) formed in an elongated shape along the Y direction. This causes the illumination light to be formed in a slit shape on the fundus conjugate plane (the area illuminated in a slit shape on the fundus is illustrated as symbol B).

[0036] In Fig. 2, the slit forming section 15a is displaced by the driving section 15c so that the light transmitting section crosses the photographing optical axis L in the X direction. This realizes the scanning of the illumination light in this embodiment. In this embodiment, scanning is also performed by the slit forming section 15b on the light receiving system side. In this embodiment, the slit forming sections 15a, 15b on the light projecting side and the light receiving side are driven in conjunction with each other by one driving section (driver).

[0037] In the irradiation optical system 10a, the images of the light sources are relayed by the optical system from the lens 13 to the objective lens 22 and formed on the pupil conjugate plane. That is, on the pupil conjugate plane, images of the two light sources are formed at positions separated in the scanning direction. In this way, in this embodiment, the two light projection areas P1 and P2 (exit pupils in this embodiment) on the pupil conjugate plane are formed as images of the two light sources.

[0038] The slit-shaped light that has passed through the slit forming portion 15a is relayed by the optical system from the lens 17a to the objective lens 22, and forms an image on the fundus Er. This forms a slit-shaped illumination light on the fundus Er. The illumination light is reflected on the fundus Er and taken out from the pupil Ep.

[0039] Here, since the aperture of the perforated mirror 20 is conjugate with the pupil of the subject's eye, the fundus reflected light used to capture the fundus image is limited to a part that passes through the image (pupil image) of the perforated mirror aperture on the pupil of the subject's eye. In this way, the image of the aperture on the pupil of the subject's eye becomes the light receiving area R (entrance pupil in this embodiment) in this embodiment. The light receiving area R is formed between two light projecting areas P1 and P2. In addition, as a result of appropriately setting the imaging magnification of each image, the diameter of the aperture, and the arrangement interval of the two light sources, the light receiving area R and the two light projecting areas P1 and P2 are formed so as not to overlap each other on the pupil. In other words, the exit pupil and the entrance pupil are separated. As a result, the occurrence of flare is effectively reduced.

[0040] The fundus reflected light that passes through the objective lens 22 and the aperture of the perforated mirror 20 forms an image of a slit-shaped region of the fundus Er at a fundus conjugate position via the lenses 25a and 25b. At this time, harmful light is removed by disposing the light transmitting portion of the slit forming portion 15b at the position of image formation.

[0041] The image sensor 28 is disposed at a fundus conjugate position. In this embodiment, a relay system 27 is provided between the slit forming section 15b and the image sensor 28, and thus both the slit forming section 15b and the image sensor 28 are disposed at a fundus conjugate position. As a result, both the removal of harmful light and the formation of an image are performed well. Alternatively, the relay system 27 between the image sensor 28 and the slit forming section 15b may be omitted, and both may be disposed in close proximity. In this embodiment, a device having a two-dimensional light receiving surface is used as the image sensor 28. For example, it may be a CMOS, a two-dimensional CCD, or the like. An image of a slit-shaped region of the fundus Er formed at the light transmitting section of the slit forming section 15b is projected onto the image sensor 28. The image sensor 28 is sensitive to both infrared light and visible light.

[0042] In this embodiment, as the slit-shaped illumination light scans the fundus Er, images (slit-shaped images) of the scanning positions on the fundus Er are sequentially projected for each scanning line of the image sensor 28. In this manner, the entire image of the scanning range is projected onto the image sensor in a time-division manner. As a result, a front image of the fundus Er is captured as the entire image of the scanning range.

[0043] The photographing optical system 10 has a diopter correction unit. In this embodiment, the diopter correction units (diopter correction optical systems 17 and 25) are provided in the independent optical paths of the irradiation optical system 10a and the receiving optical system 10b. Hereinafter, for convenience, the diopter correction optical system on the irradiation side is referred to as the irradiation side diopter correction optical system 17, and the diopter correction optical system on the receiving side is referred to as the receiving side diopter correction optical system 25. The irradiation side diopter correction optical system 17 of this embodiment includes a lens 17a, a lens 17b, and a driving unit 17c (see FIG. 3). The receiving side diopter correction optical system 25 of this embodiment includes a lens 25a, a lens 25b, and a driving unit 25c (see FIG. 3). In the irradiation side diopter correction optical system 17, the distance between the lens 17a and the lens 17b is changed, and in the receiving side diopter correction optical system 25, the distance between the lens 25a and the lens 25b is changed. This allows diopter correction to be performed in each of the irradiation optical system 10a and the light receiving optical system 10b.

[0044] <Split target projection optical system> As shown in Fig. 2, the photographing optical system 10 further includes a split index projection optical system 50 as an example of a focus index projection optical system. The split index projection optical system 50 projects two split indexes onto the fundus. The split indexes are used to detect the focus state. In this embodiment, the refractive power of the subject's eye E is obtained from the detection result of the focus state.

[0045] The split target projection optical system 50 may have at least a light source 51 (infrared light source), a target plate 52, and a deflection prism 53, for example. In this embodiment, the target plate 52 is disposed at a position corresponding to the imaging surface in the light receiving optical system 50. Similarly, the target plate 52 is disposed at a position corresponding to each of the slit forming portions 15a and 15b. In detail, when the diopter correction amount on the irradiation side and the light receiving side is 0D, the target plate 52 is disposed at a position approximately conjugate with the fundus of the emmetropic eye (0D eye). The deflection prism 53 is disposed closer to the target plate 52 than the target plate 52 and in the vicinity of the target plate 52.

[0046] The index plate 52 forms, for example, a slit light as an index. The deflection prism 53 splits the index light flux passing through the target plate 52 to form a split index. The split index is projected onto the fundus of the subject's eye via the irradiation-side diopter correction optical system 17 and the objective lens 22. Therefore, the split index is reflected in a fundus image (for example, a fundus observation image).

[0047] When the index plate 52 is displaced from the fundus conjugate position, the two split indices are separated on the fundus, and when the index plate 52 is placed at the fundus conjugate position, the two split indices are matched. The conjugate relationship is adjusted by the illumination-side diopter correction optical system 17 placed between the angle-deviating prism 53 and the subject's eye Er. In this embodiment, therefore, defocusing is performed while matching the illumination-side diopter correction amount and the light-receiving-side diopter correction amount. At this time, the separation state of the split indices indicates the focus state. By adjusting each of the illumination-side and light-receiving-side diopter correction amounts so that the two split indices are matched, the imaging surface and the slit forming units 15a and 15b each have a positional relationship conjugate with the fundus.

[0048] <Barrier filter> The photographing device 1 further includes a barrier filter 61. During fluorescence photographing, the light receiving optical system 10b guides the fluorescence from the fundus based on the excitation light to the image sensor 28. The barrier filter 61 may be disposed on an independent optical path of the light receiving optical system. The barrier filter 61 has a spectral characteristic that blocks light in the same wavelength range as the excitation light and passes the fluorescence. As an example, in this embodiment, the barrier filter 61 has a spectral characteristic suitable for spontaneous fluorescence photographing. For example, it blocks green or blue light, which is the excitation light, and passes light on the longer wavelength side to the image sensor 28 side. This allows the spontaneous fluorescence to be selectively received by the image sensor 28. As a result, a satisfactory spontaneous fluorescence image of the fundus is obtained. The photographing device 1 may include a drive unit 61a that inserts and removes the barrier filter 61. The insertion and removal of the barrier filter is controlled by, for example, the control unit 100.

[0049] <Anterior segment observation optical system> Next, the anterior-segment observation optical system 40 will be described. The anterior-segment observation optical system 40 shares the objective lens 22 and the dichroic mirror 43 with the photographing optical system 10. The anterior-segment observation optical system 40 further includes a light source 41, a half mirror 45, an image sensor 47, etc. The image sensor 47 is a two-dimensional image sensor, and is disposed, for example, at a position optically conjugate with the pupil Ep. The anterior-segment observation optical system 40 illuminates the anterior segment with infrared light and captures a front image of the anterior segment.

[0050] It should be noted that the anterior eye observation optical system 40 shown in FIG. 2 is merely an example, and the anterior eye may be imaged in an optical path independent of other optical systems.

[0051] <Details of the Optical Chopper> In this embodiment, an optical chopper 150 as shown in FIG. 4 is used as the slit forming units 15a and 15b and the driving unit 15c (see FIG. 3) of the photographing optical system 10. FIG. 4 is a diagram showing an optical chopper 150 applicable as a scanning unit in the optical system of FIG. 2. The optical chopper 150 has a wheel 151 with a plurality of slit openings formed on its outer circumference, and can scan the slits at high speed by rotating the wheel 151. Note that the slit openings in FIG. 4 are drawn diagrammatically. The wheel 151 is an example of a rotating body. The wheel 151 corresponds to the slit forming units 15a and 15b shown in FIG. 2. The main body 152 includes a driving unit 15c. The driving unit 15c is, for example, a motor capable of switching the direction of rotation between forward and reverse.

[0052] 2, the light source unit 11 to the mirror 18 of the irradiation optical system 10a and the perforated mirror 20 to the image sensor 28 of the light receiving optical system 10b are arranged in parallel in the X direction, but for example, by rotating the perforated mirror 20 and the mirror 18 by 90 degrees from the illustrated state and arranging them in parallel in the Y direction, the optical chopper 150 can be used as a scanning unit. In this case, by making the optical axis of the irradiation optical system 10a and the optical axis of the light receiving optical system 10b cross each other at two points, the upper end and the lower end of the wheel 151, the single optical chopper 150 can easily synchronize the scanning of the light projection system and the light receiving system.

[0053] In FIG. 4, position P1 below wheel 151 is defined as a position through which the optical axis of irradiation optical system 10a passes, and position P2 symmetrical to position P1 with respect to rotation center O is defined as a position through which the optical axis of light receiving optical system 10b passes.

[0054] Fig. 5 is a diagram showing a slit plate which is a part of the slit forming portion according to the embodiment, and Fig. 6 is a diagram showing a mask which is a part of the slit forming portion according to the embodiment.

[0055] In this embodiment, as shown in Fig. 5 and Fig. 6, the wheel 151 is formed by a slit plate 160 and a mask 180. Both are arranged overlapping along the optical axis with their rotation axes (rotation axis 161, rotation axis 181) coinciding with each other. In addition, the slit plate 160 and the mask 180 are rotated around their respective rotation axes (rotation axis 161, rotation axis 181) by transmitting power from the driving unit 15c.

[0056] In relation to the configuration of the slit plate 160 and the mask 180, the optical chopper 150 is provided with a switching mechanism 155 for switching the area ratio between the slit opening and the light blocking portion in the wheel 151. For example, when the slit plate 160 and the mask 180 are rotated by the drive unit 15c, the switching mechanism 155 changes the positional relationship between the slit plate 160 and the mask 180 according to the forward and reverse rotation direction, thereby switching the area ratio between the slit opening and the light blocking portion. In relation to the switching mechanism 155, the optical chopper 150 is provided with a fixing mechanism 157 for fixing the positional relationship between the slit plate 160 and the mask 180 in conjunction with the forward and reverse rotation directions of the slit plate 160 and the mask 180. Specific examples of the switching mechanism 155 and the fixing mechanism 157 will be described below.

[0057] 5, the slit plate 160 has two types of slit openings 163 and 165 with different widths, the same number of each, and they are arranged alternately. In this embodiment, 16 slit openings 163 and 165 are arranged at regular intervals (equidistant intervals). For example, the slit opening 163 is a wide slit opening and is used when obtaining a color fundus image. The slit opening 165 is a narrower slit opening than the slit opening 163 and is used when obtaining a fluorescent image of the fundus.

[0058] In FIG. 6, the mask 180 is a member for blocking one of the two types of slit openings 163, 165 formed in the slit plate 160 and opening the other. In this embodiment, the mask 180 has 16 slit openings 183 arranged at regular intervals so that a light-shielding portion 182 is formed between adjacent slit openings when the mask 180 is overlapped with the slit plate 160. The slit openings 183 are formed to be wider than either of the slit openings 163, 165. The regions between the 16 slit openings 183 are defined as the light-shielding portions 182. The mask 180 partially or selectively blocks the openings (slit openings 163, 165) formed in the slit plate 160.

[0059] In this embodiment, the rotation shaft 161 of the slit plate 160 is directly connected to the rotation shaft of the drive unit 15c. In other words, the power from the drive unit 15c is directly transmitted without delay. In addition, the mask 180 is attached to the slit plate 160 so as to be slidable in the rotation direction by a predetermined movement amount.

[0060] 6, a pin 187 is attached to the mask 180. In this embodiment, the pin 187 is composed of two pins, a first pin 187A and a second pin 187B. The first pin 187A and the second pin 187B are each held on the mask 180 by a holder 190 so as to be movable along a groove 188 extending in the radial direction of the mask 180 with respect to the rotation center O. The pin 187 is an element of the switching mechanism 155, and the groove 188 and the holder 190 are elements of the fixing mechanism 157.

[0061] 7 is a diagram for explaining holding portion 190 of first pin 187A by mask 180, and shows an enlarged view of the A-A cross section of first pin 187A in FIG. 6. For example, an annular groove 187m corresponding to the plate thickness of mask 180 is formed on the side surface of first pin 187A made of a cylindrical member. The inner cylindrical portion of annular groove 187 is inserted into groove 188 on the mask 180 side, so that first pin 187A is held by mask 180 so as to be movable along groove 188. Similarly, second pin 187B is held by holding portion 190 so as to be movable along groove 188 extending in the radial direction of mask 180.

[0062] A pulling force is applied to first pin 187A and second pin 187B in a direction toward center of rotation O by spring 189, which is an example of a pulling force applying portion. Spring 189 is an element of fixing mechanism 157. Here, the pulling force of spring 189 is set to be smaller than the centrifugal force acting on pin 187 as mask 180 rotates. The centrifugal force acting on pin 187 is mathematically determined from the relationship between the mass of pin 187, the radius of the position of pin 187 relative to center of rotation O, and the angular velocity of pin 187 as mask 180 rotates. Note that magnetic force may be used to apply the pulling force.

[0063] 5, the slit plate 160 is provided with a connecting hole 167 into which a pin 187 is inserted. The slit plate 160 and the mask 180 are connected via the pin 187 and the connecting hole 167. In this embodiment, since there are two pins 187, the connecting hole 167 also consists of a first connecting hole 167A into which a first pin 187A is inserted and a second connecting hole 167B into which a second pin 187B is inserted. The connecting hole 167 is an element of the switching mechanism 155.

[0064] FIG. 8 is a diagram for explaining the connecting hole 167, and is an enlarged view of the vicinity of the connecting hole 167 in FIG. 5. First, the first connecting hole 167A is an elongated hole having a length extending by a distance DA in the circumferential direction based on the rotation center O. The circumferential distance DA corresponds to the interval (1 / 32 of a circumference in this embodiment) between two types of adjacent slit openings 163, 165 in the slit plate 165, and is formed to a length that allows the first pin 187A to move in response to a predetermined amount of movement associated with the forward and reverse rotation directions of the wheel 151. That is, the distance DA is determined as follows. In FIG. 8, the circle indicated by the dotted line in the connecting hole 167 indicates the outline at the position where the pin 187 is moved relative to the connecting hole 167.

[0065] For example, with respect to the center of rotation O, the angle formed by a line LA1 passing through the center of the width of slit opening 163 (the width of the slit opening perpendicular to the longitudinal direction) and a line LA2 passing through the center of the width of adjacent slit opening 165 is defined as α (see FIG. 5). Furthermore, when the radius of pin 187 (first pin 187A) is r and the radius R relative to the center of rotation O is the radius of first connecting hole 167A in which the center of pin 187 (first pin 187A) is located, the distance DA is mathematically determined by the angle α, radius r, and radius R.

[0066] Since the first connecting hole 167A and the first pin 187A having the distance DA thus determined are connected to each other, the rotation of one of the rotating bodies, the slit plate 160 and the mask 180, is delayed by a predetermined movement amount (approximately 1 / 32 rotation=angle α in this embodiment) from the rotation of the other rotating body. In this case, the switching mechanism 155 functions as a delay generating mechanism that delays the power transmission from the drive unit 15c to the slit plate 160 and the mask 180 by a predetermined movement amount between the slit plate 160 and the mask 180.

[0067] For example, when the wheel 151 is rotated in the forward direction, the slit plate 160 and the mask 180 are shifted (displaced) in the opposite direction by a predetermined amount of movement relative to one of the rotating bodies. On the other hand, when the slit forming part is rotated in the reverse direction, the slit plate 160 and the mask 180 are shifted (displaced) in the forward direction by a predetermined amount of movement relative to one of the rotating bodies. This delay generating mechanism does not require an extra actuator for switching, and the area ratio of the slit opening and the light blocking part can be switched by using the drive part 15c with a simple configuration in which the positional relationship between the slit plate 160 and the mask 180 is simply switched. In other words, the delay generating mechanism is a displacement generating mechanism for shifting the power transmission from the drive part 15c between the slit plate 160 and the mask 180 by a predetermined amount of movement.

[0068] In this embodiment, the slit plate 160 is rotated by the driving unit 15c, and the pin 187 is connected to the connecting hole 167, so that the rotation of the slit plate 160 is transmitted to the mask 180. That is, the mask 180 is rotated subordinately to the rotation of the slit plate 160.

[0069] In addition, the connecting hole 167 is formed with a fixing hole 168 extending radially outward from the rotation center O in correspondence with the above-mentioned predetermined movement amount. The fixing hole 168 allows the pin 187 to move. The fixing hole 168 may be formed in such a shape that, when the pin 187 is inserted, both the forward and reverse rotations of the mask plate 160 relative to the pin 187 are fixed. In the first connecting hole 167A, a first fixing hole 168A extending in the line LA1 direction is formed. The length DB of the first fixing hole 168A in the line LA1 direction relative to the first connecting hole 167A may be such that the first pin 187A does not come out of the first fixing hole 168A when moved to the first fixing hole 168A located radially outward even if the rotation unevenness of the wheel 151 occurs. For example, the length DB of the first fixing hole 168A is set to be greater than the radius r of the first pin 187A when the first pin 187A is positioned on the line LA1 of the first connecting hole 167A. Therefore, when the first pin 187A is moved to the first fixing hole 168A by the centrifugal force acting on the first pin 187A, the positional relationship between the slit plate 160 and the mask 180 is fixed.

[0070] It is sufficient that the first fixing hole 168A is formed to have a catch that prevents the slit plate 160 from rotating in the opposite direction to the rotation direction. In this embodiment, the width of the first connecting hole 167A in the direction perpendicular to the line LA1 direction is slightly larger than the diameter of the first pin 187A (to the extent that the width of the slit opening does not change due to the light-shielding part of the mask 180). This makes it difficult for the first pin 187A to come off the first fixing hole 168A while the slit plate 160 is rotating.

[0071] In FIG. 8, the second connecting hole 167B is also formed with a second fixing hole 168B based on the same design concept as the first connecting hole 167A. However, while the first fixing hole 168A is formed in the direction of the line LA1, the second fixing hole 168B is formed in the direction of the line LA2. That is, the second fixing hole 168B is a line LB perpendicular to the line LA3 located midway between the lines LA1 and LA2, and is symmetrical with respect to the line LB passing through the center of rotation O. Therefore, when the first pin 187A is positioned on the line LA2 of the first connecting hole 167A, the second pin 187B is positioned on the line LA2 of the second connecting hole 167B, and the second pin 187B is moved toward the second fixing hole 168B by the centrifugal force acting on the second pin 187B. As a result, the positional relationship between the slit plate 160 and the mask 180 is fixed in response to switching of the slit plate 160 and the mask 180 by a predetermined amount of movement.

[0072] Also, a first recess 169A may be formed in first connecting hole 167A at a middle position (which may be a substantially middle position) of the above-mentioned predetermined movement amount (1 / 32 circumference=angle α) to move first pin 187A toward rotation center O. First recess 169A is formed so that the distance from rotation center O gradually decreases toward the middle position of first connecting hole 167A. Second connecting hole 167B may also be formed with second recess 169B, which is designed in a similar way to first recess 169A.

[0073] When the rotation of the slit plate 160 is stopped, the first pin 187A and the second pin 187B are not subjected to centrifugal force, and therefore the first pin 187A and the second pin 187B are both pulled toward the rotation center O by the spring 189. Therefore, as shown in FIG. 9 (FIG. 9 is a diagram showing the positional relationship between the connecting hole 167 and the pin 187 when the rotation of the slit plate 160 is stopped), the first pin 187A is located in the first recess 169A of the first connecting hole 167A, and the second pin 187B is located in the second recess 169B of the second connecting hole 167B. This makes it easier to stably and smoothly switch the predetermined amount of movement when the slit plate 160 is rotated in either the forward or reverse direction.

[0074] In this embodiment, there are two sets of connecting holes 167 and pins 187, and the centers of gravity of the two sets coincide with the rotation center O (approximately coincide with the rotation center O in this embodiment). Compared with the case of one set of connecting holes and pins described in JP2022-42896A, the center of gravity is not biased, and the slit plate 160 and the mask 180 rotate integrally in a well-balanced manner. In addition, even if three or more sets of connecting holes 167 and pins 187 are provided, it is sufficient that their centers of gravity are approximately coincident with the rotation center O.

[0075] As described above and shown in Figures 5 to 8, the switching mechanism 155 in this embodiment mainly includes a pin 187 and a connecting hole 167 as its components, and the fixing mechanism 157 mainly includes a groove 188, a holding portion 190 and a fixing hole 168 as its components.

[0076] <Control system> Next, a control system of the photographing device 1 will be described with reference to Fig. 3. In this embodiment, the control unit 100 controls each unit of the photographing device 1. The control unit 100 also processes various images obtained by the photographing device 1. In other words, in this embodiment, the control unit 100 also functions as an image processing unit.

[0077] The control unit 100 is a processing device (processor) having electronic circuits that perform control processing of each unit and arithmetic processing. The control unit 100 is realized by a CPU (Central Processing Unit) and a memory, etc. The control unit 100 is electrically connected to a storage unit 101 via a bus, etc. The storage unit 101 stores various control programs and fixed data, etc. In addition, temporary data, etc. may be stored in the storage unit 101. Images captured by the photographing device 1 may be stored in the storage unit 101. However, this is not necessarily limited to this, and the captured images may be stored in an external storage device (for example, a storage device connected to the control unit 100 via a LAN and a WAN).

[0078] The control unit 100 is also connected to various electric elements such as the drive unit 8, light sources 11a to 11d, image sensor 28, light source 41, image sensor 47, light source 51, input interface 110, and monitor 120. The control unit 100 controls the above-mentioned various components based on an operation signal output from the input interface 110 (operation input unit). The input interface 110 is an operation input unit that accepts an operation by an examiner. For example, the input interface 110 may be a mouse and a keyboard. The monitor 120 may be a touch panel, so that the monitor 120 has the function of the operation input unit.

[0079] <Operation> The operation of the imaging device 1 having the above-mentioned configuration will be described below, focusing on the change of the positional relationship between the slit plate 160 and the mask 180 and the operation of fixing the same.

[0080] First, the photographing unit 3 is aligned in a predetermined positional relationship with respect to the subject's eye on the subject's face supported by the face support part 9. For example, an anterior eye image of the subject's eye is captured by the imaging element 47 of the anterior eye observation optical system 40, and the driving of the driving part 8 is controlled to move the photographing unit 3 in the up, down, left and right directions so that the pupil center in the anterior eye image approximately coincides with the position of the photographing optical axis L. Also, the driving of the driving part 8 is controlled to move the photographing unit 3 in the working distance direction with respect to the subject's eye so that the pupil of the anterior eye image captured by the imaging element 47 is focused.

[0081] During alignment adjustment, the infrared light sources 11c and 11d are turned on, and the fundus of the subject eye is illuminated with infrared light by the irradiation optical system 10a. During alignment adjustment, the slit plate 160 is rotated clockwise by the drive unit 15c, and a narrow slit opening 165 is selected (the operation of switching the slit opening will be described in detail later), and the slit-shaped illumination light by the slit opening 165 is repeatedly scanned. Then, based on the signal output from the image sensor 28 every time the slit opening 165 passes through the optical path, the control unit 100 generates a fundus observation image at any time, and the image is displayed on the monitor 120 as a substantially real-time moving image.

[0082] In addition, the focus state in the irradiation optical system 10a and the light receiving optical system 10b is adjusted based on the acquired fundus observation image. In this embodiment, the diopter correction unit is driven to perform focus adjustment. At this time, both the irradiation side diopter correction optical system 17 and the light receiving side diopter correction optical system 25 of the diopter correction unit are driven. The focus adjustment for the fundus of the subject eye is performed by adjusting both the irradiation side diopter correction amount and the light receiving side diopter correction amount so that the two split indices appearing in the fundus observation image by the split target projection optical system 50 match.

[0083] When the alignment adjustment of the subject's eye and the focus adjustment of the fundus are completed, the fundus can be photographed. In this embodiment, a normal color photography mode and a fluorescent photography mode can be set (selected) as the photography mode. The color photography mode is set to photograph a fundus image based on fundus reflected light. The fluorescent photography mode is set to photograph a fluorescent fundus image. For example, the photography mode is set by the examiner operating the operation input unit of the input interface 110.

[0084] When the normal color photography mode is set, the light sources 11a and 11b simultaneously emit light of three colors, R (red), G (green), and B (blue). The barrier filter 61 is retracted from the optical path of the light receiving optical system 10b, and a fundus image is generated based on the exposure of the image sensor 28 of the light receiving optical system 10b. In this color photography mode, the positional relationship between the slit plate 160 and the mask 180 is changed so that the area ratio of the light blocking portion and the slit opening in the wheel 151 (slit forming portions 15a and 15b) is switched depending on whether the slit plate 160 is rotated forward or backward. In this embodiment, in the color photography mode, the switching mechanism 155 switches so that the light beam passes through the narrow slit opening 165. By setting the width of the slit-shaped photography area on the fundus to be relatively narrow, a photography image in which artifacts due to reflection at the objective lens 22 and the like are suppressed is photographed.

[0085] In the normal color photography mode, in this embodiment, the slit plate 160 is rotated clockwise. In this case, as shown in Fig. 10, the counterclockwise end of the first connecting hole 167A is moved until it abuts against the first pin 187A, and then the rotational driving force of the slit plate 160 is transmitted to the mask 180 via the first pin 187A. At this time, the positional relationship between the slit plate 160 and the mask 180 is such that the slit opening 183 of the mask 180 is positioned corresponding to the slit opening 165, and the slit opening 165 is exposed.

[0086] On the other hand, with regard to second pin 187B, after the counterclockwise end of second connecting hole 167B is moved until it abuts against second pin 187B, centrifugal force acting on second pin 187B causes second pin 187B to move into second fixing hole 168B against the pulling force of spring 189. As a result, while wheel 151 is rotating, the positional relationship between slit plate 160 and mask 180 is fixed in conjunction with the rotation direction of slit plate 160 with slit opening 165 exposed. Therefore, even if rotation unevenness (unstable rotation speed, acceleration, etc.) occurs in the rotating body (i.e. wheel 151), the area of ​​the slit opening does not change during the rotation, and a photographed image with good brightness can be obtained.

[0087] Next, a case where the fluorescent photography mode is set will be described. When the fluorescent photography mode is set, one color, G (green), is emitted from the light sources 11a and 11b during photography. Also, a barrier filter 61 is inserted into the optical path of the light receiving optical system 10b. As a result of inserting the barrier filter 61, it becomes unnecessary to consider the above-mentioned artifacts. When a photography trigger signal is received by the control unit 100, the slit plate 160 (i.e., the wheel 151) is rotated counterclockwise, opposite to the normal color photography mode, to switch to a slit opening 163 with a wider slit opening. That is, in the fluorescent photography mode, photography is performed with a wider slit opening than in the normal photography mode.

[0088] 11, when the slit plate 160 is rotated counterclockwise, the clockwise end of the second connecting hole 167B moves until it abuts against the second pin 187B, and the rotational driving force of the slit plate 160 is transmitted to the mask 180 via the second pin 187B. At this time, the positional relationship between the slit plate 160 and the mask 180 is such that the slit opening 183 of the mask 180 is positioned corresponding to the slit opening 163, exposing the slit opening 165.

[0089] On the other hand, first pin 187A is moved until the clockwise end of first connecting hole 167A abuts against first pin 187A, and then centrifugal force acting on first pin 187A causes first pin 187A to move into outer first fixing hole 168A against the pulling force of spring 189. As a result, the positional relationship between slit plate 160 and mask 180 is fixed in conjunction with the rotation direction of the rotating body while wheel 151 is rotating. Therefore, even if the rotation of the rotating body (wheel 151) is uneven, a photographed image with good brightness can be obtained.

[0090] When the rotation direction of the wheel 151 is reversed after a fundus observation image has been acquired, there is a time lag between when the rotation is reversed and when the desired rotation speed is reached. Therefore, when a fundus fluorescence image is to be photographed, the fundus fluorescence image is captured after a sufficient amount of time has elapsed since the photographing trigger signal was received.

[0091] As described above, the rotation of the slit plate 160 is switched between clockwise and counterclockwise by the driving unit 15c, so that one of the two types of slit openings 163 and 165 having different widths is selectively exposed. This makes it possible to switch the area ratio between the slit openings and the light blocking portion.

[0092] In this embodiment, as described above, as long as the wheel 151 is rotated in one direction, the positional relationship between the slit plate 160 and the mask 180 is fixed, and the width of the slit opening passing through the optical path is constant, so that fundus images are captured efficiently. That is, scanning with an inappropriate amount of light is easily suppressed, and in continuous shooting such as video shooting, a frame rate is easily ensured. In addition, since the shooting time per image is easily shortened, distortion due to eye movement is easily suppressed.

[0093] <Example of transformation> Although typical embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments shown here, and various modifications are possible.

[0094] For example, in the above embodiment, the slit forming units 15a and 15b selectively block light from two types of slit openings 163 and 165 formed in the slit plate 160 using the mask 180, but the present invention is not limited to this. The slit forming units 15a and 15b may be configured such that the width of one type of slit opening formed in the slit plate 160 is partially blocked by the mask 180 to form a narrow slit opening used in a normal color imaging mode and a wide slit opening used in a fluorescent imaging mode.

[0095] In the above embodiment, the slit plate 160 is directly rotated by the drive unit 15c, but the mask 180 may be directly rotated by the drive unit 15c. That is, the rotational power of the drive unit 15c may be directly transmitted to one of the rotating bodies of the slit plate 160 and the mask 180, and the rotational power may be indirectly (subordinately) transmitted to the other rotating body through the connection of the pin 187 and the connection hole 167.

[0096] Also, for example, the rotating body on which the pin 187 and the connecting hole 167 are arranged may be reversed from the above embodiment, with the pin 187 being arranged on the slit plate 160 and the connecting hole 167 being arranged on the mask 180.

[0097] In the above embodiment, an example in which two sets of connecting holes 167 and pins 187 are provided has been described, but these may be one set. Fig. 12 is a diagram for explaining fixing mechanism 155 in the case where connecting hole 167 and pin 187 are one set, and is a diagram showing an example of modification of connecting hole 167 of slit plate 160. In this case, for example, in mask 180, one pin 187 of first pin 187A and second pin 187B shown in Fig. 6 is used, and the other pin 187 and the associated groove 188 and spring 189 are eliminated.

[0098] 12, the connecting hole 167C is formed with a fixing hole 168C extending radially outward in the direction of the line LA2 with respect to the first connecting hole 167A shown in FIG. 8. The fixing hole 168C has a design concept similar to that of the first fixing hole 168A in FIG. 8, and the pin 187 is moved. When the slit plate 160 is rotated clockwise, the counterclockwise end of the connecting hole 167C is moved until it abuts against the pin 187, and then the pin 187 is moved to enter the fixing hole 168C by the centrifugal force acting on the pin 187. As a result, the positional relationship between the slit plate 160 and the mask 180 is fixed, and the slit opening 165 is exposed. When the slit plate 160 is rotated counterclockwise, as in FIG. 11, the pin 187 is moved to enter the first fixing hole 168A, thereby fixing the positional relationship between the slit plate 160 and the mask 180 with the slit opening 165 exposed.

[0099] When the connecting hole 167 and the pin 187 are one pair, the rotating body on which the pin 187 is arranged may be provided with a weight for balancing in the opposite direction with respect to the center of rotation O, and the rotating body on which the connecting hole 167 is arranged may be provided with a dummy hole for balancing in the opposite direction with respect to the center of rotation O. This provides good balance to the center of gravity of the wheel 151 during rotation.

[0100] In the above embodiment, a pulling force applying mechanism (e.g., spring 189) is provided to apply a pulling force to move pin 187 toward the rotation center O, but a special pulling force applying mechanism is not necessarily required. For example, the pin 187 may be configured to be disengaged from the fixing hole 168 when the wheel 151 stops due to gravity acting on the pin 187. For example, as shown in FIG. 12, in the case of the connecting hole 167 and the pin 187, the rotation of the wheel 151 (the slit plate 160 in this embodiment) is stopped in a state where the connecting hole 167 and the pin 187 are positioned vertically above the rotation center O. In this case, since the connecting hole 167 extending in the circumferential direction is positioned below the fixing hole 168, the pin 187 is disengaged from the fixing hole 168 by the action of gravity and moved toward the connecting hole 167. When the wheel 151 rotates at high speed, the pin 187 is moved to the fixing hole 168 according to the forward or reverse direction of the rotation, and the positional relationship between the slit plate 160 and the mask 180 is fixed.

[0101] In the above description, the fixing mechanism 157 for fixing the positional relationship between the slit plate 160 and the mask 180 uses the centrifugal force acting on the pin 187 as the wheel 151 rotates, but is not limited to this. For example, a latch mechanism may be provided on the connecting hole 167 side, and the rotating body on the pin 187 side may be fixed by the latch mechanism in conjunction with switching the rotation direction of the rotating body. In this case, if a stopper mechanism is provided that stops the rotation of the dependent rotating body when the rotation direction of the rotating body is switched, the fixing by the latch mechanism can be performed more reliably. For example, the stopper mechanism may be a mechanism that applies a frictional force to the side of the rotating body when the rotation direction is switched to stop the rotating body from moving, or a mechanism that inserts a pin into the engagement hole. Then, when the rotation is resumed, the stopper mechanism may be released. [Explanation of symbols]

[0102] 1. Imaging device 10. Shooting optical system 10a Irradiation optical system 10b Light receiving optical system 15a, 15b Slit forming section 15c Drive unit 150 Optical Chopper 155 Switching mechanism 157 Fixing mechanism 160 Slit plate 163 Slit Aperture 165 Slit Aperture 167 Connection hole 168 Fixing hole 169A, 169B recess 180 Mask 187 Pin 189 Spring 190 Holding part

Claims

1. A fundus imaging apparatus comprising an illumination optical system for irradiating illumination light onto the fundus of the eye under examination, and a light-receiving optical system including an image sensor for receiving the reflected light from the fundus of the illumination light, wherein a fundus image, which is a frontal image of the fundus, is acquired based on the light-receiving signal from the image sensor, The aforementioned imaging optical system is A slit forming unit comprising a slit opening and a light-shielding portion for forming a slit-shaped imaging area on the fundus, wherein a slit plate and a mask for partially or selectively shielding the opening formed in the slit plate are arranged superimposed along the optical axis, thereby forming the slit opening via the slit plate and the mask. A drive unit that rotates the slit forming unit in a direction in which the long side of the slit opening intersects at least one of the light beams of the illumination light and the reflected light, and a drive unit capable of reversing the rotation direction of the slit forming unit, A switching mechanism that changes the positional relationship between the slit plate and the mask according to the forward and reverse directions of rotation, thereby switching the area ratio between the light-shielding portion and the slit opening in the slit forming portion, A fixing mechanism that fixes the positional relationship between the slit plate and the mask, which has been changed by the switching mechanism, in conjunction with the rotation of the slit forming section, A fundus imaging device characterized by being equipped with the following features.

2. In the fundus imaging apparatus of claim 1, The switching mechanism is a delay mechanism that, when the forward or reverse direction of rotation is switched, delays the transmission of power from the drive unit to the slit plate and the mask by a predetermined amount of movement between the slit plate and the mask. The fundus imaging apparatus is characterized in that the fixing mechanism is a mechanism that fixes a delay of a predetermined amount of movement in conjunction with the forward and reverse rotation of the rotational direction.

3. In the fundus imaging apparatus of claim 2, The aforementioned delay generation mechanism is A pin is provided on one of the first rotating bodies of the slit plate and the mask, The slit plate and the other second rotating body of the mask are provided with a connecting hole into which the pin is inserted, The drive unit rotates one of the first and second rotating bodies, thereby transmitting power from the drive unit to the other rotating body through the connection between the pin and the connecting hole. The connecting hole has a length that allows the pin to move in accordance with the predetermined amount of movement associated with the forward and reverse directions of rotation. The aforementioned fixing mechanism is A pin holding portion that holds the pin so as to be movable in the radial direction with respect to the rotation center of the first rotating body, The pin is movable outward in the radial direction of the second rotating body, corresponding to the predetermined amount of movement associated with the forward and reverse rotation directions, and the connecting hole is provided in the connecting hole, The fundus imaging apparatus is characterized in that the positional relationship between the slit plate and the mask is fixed by the centrifugal force accompanying the rotation of the first rotating body, which moves the pin to the fixing hole.

4. In the fundus imaging apparatus of claim 3, The fixing mechanism has a tensile force applying part that applies a tensile force to the pin so as to move it toward the rotation center of the first rotating body, The fundus imaging apparatus is characterized in that the tensile force is set to be smaller than the centrifugal force acting on the pin as the first rotating body rotates.

5. In the fundus imaging apparatus of claim 3 or 4, A fundus imaging apparatus characterized in that multiple sets of the aforementioned pins, connecting holes, and fixing mechanisms are provided, and their centers of gravity coincide with the rotation centers of the slit plate and the mask.

Images