JPS6257340B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fundus camera suitable for general photography and fluorescence fundus photography.

Fluorescence fundus photography is one type of fundus photography, in which the fundus is illuminated with excitation light with a wavelength near blue, timing the time that frioretsen sodium, etc. injected through the cubital vein reaches the intraocular circulation system, and then removing the blood from the blood column. This is performed by generating fluorescent light and photographing only the fluorescent light from among the reflected light from the subject's eye. At that time, a barrier filter is installed in the imaging optical path and an exciter is installed in the illumination optical path to separate wavelengths, so the amount of light decreases depending on the transmission characteristics of the filter, and the fluorescence generated in the fundus of the eye decreases. Since the light emission rate is quite low, a larger amount of illumination light is required compared to general color photography.

On the other hand, in a fundus camera in which the imaging system and illumination system are arranged coaxially, a sunspot is provided in the illumination optical path to prevent part of the illumination system from reflecting off the cornea and entering the imaging system. A method of blocking reflected light in advance has been practiced for a long time. However, recently,
As objective lenses became wider (45 degrees), harmful light reflected by the crystalline lens became a problem. This is because with a conventional fundus camera (30°), the sunspot shadow, or image, covers not only the reflective area of the cornea but also the crystalline lens. This is because the shadow is shortened and harmful light is also generated in the crystalline lens.

As a countermeasure for this, Japanese Patent Publication No. 51-24249 removes the light reflected by the crystalline lens surface by forming a sunspot image on the front surface or between the front and back surfaces of the crystalline lens. A sunspot is provided in the illumination system that is conjugate with the posterior surface to remove scattered light from within the crystalline lens and the posterior surface of the crystalline lens.

By the way, forming a sunspot image within the subject's eye means that the amount of illumination light decreases accordingly, which is inconvenient for fluorescence fundus photography.

On the other hand, since the angle of view of the fundus illumination system of the fundus camera is constant, a certain range is always illuminated, and if variable magnification is possible, it is set to the wide-angle side, so the narrow-angle On the side, the area is illuminated beyond the area that is actually photographed. In the case of a concave surface such as the fundus of the eye, scattered reflected light generated in the peripheral area is likely to cause ghosts or flares.

In Japanese Patent Application No. 53-49025 (Japanese Unexamined Patent Publication No. 54-141095), this type of difficulty can be eliminated since the periphery of the photographed area is shielded from light by the image of the aperture.

An object of the present invention is to eliminate harmful light generated by the anterior segment and fundus of an eye to be examined, and to increase the amount of illumination light when performing special photography.

A first embodiment will be described below with reference to the drawings.

In the figure, E is the eye to be examined, Ef is the fundus, Ec is the cornea, and Ep is the pupil. Reference numeral 1 denotes an objective lens, which is set at a certain distance from the eye E to be examined and has a function of forming a fundus image. Reference numeral 2 denotes a perforated mirror having an aperture 2a, and the aperture 2a functions as a photographic diaphragm. 3 is a focusing lens, 4 is a fixed lens, 5 is a relay lens, 7 and 8 are lenses that move for variable magnification, and the lenses 3 to 8 constitute a variable magnification imaging system.
9 is a shutter, 10 is a photographic film, and the above members 1 to 10 constitute a photographing system.

In addition, focusing for photography is done using relay lens 5.
The optical path length between the lens and the film 10 may be changed, and the variable magnification imaging system may employ a method in which a turret type lens with different focal lengths is attached in addition to the zoom lens.

Next, reference numeral 11 denotes a focus shaft, which is connected to a focus knob (not shown). Reference numeral 12 denotes a focusing lever, which is fixed to the focusing shaft 11 on one side and connected to the focusing lens 3 through a pin and an elongated hole on the other hand, so that the focusing lens 3 moves in the direction of the optical axis when a focusing operation is performed. .

A zooming shaft 13 is connected to a zooming knob or a zooming motor, and a magnification small gear 14 is fixed to this shaft. 15 is a variable power gear. Reference numeral 16 denotes a part of a cam ring, and a cam groove is formed on the tube, and each cam ring is engaged with a pin fixed to the lens group. The other side of the pin engages with a linear cam in the optical axis direction, but this is not shown. The variable power large gear 15 is fixed to the cam tube 16, and meshes with the variable power small gear 14 for driving, and when the variable power small gear 14 is rotated, the large variable power gear is driven and rotates to the cam tube. Rotate 16 and change magnification lens 7
and 8 respectively along predetermined cam curves.

Next, 17 is a flip-up mirror, and when observing, the photographic lens 5
It is installed obliquely between the shutter 9 and the shutter 9, guides the finder light beam by reflection, and is retracted out of the photographing optical path during photographing. A field lens 18 is arranged at a position substantially conjugate with the film 10 with respect to the mirror 17. 19 is a mirror for changing the optical path, and 20 is an eyepiece. Further, 21 is a light source for observation such as an incandescent bulb, 22 is a condenser mirror, 23 is a first condenser lens, 24 is a light source for photography such as a strobe tube, and 25 is a second condenser lens.
Reference numeral 26 denotes a ring slit plate having an annular opening, and a light shielding area 26a at the center serves to form a shadow area through which photographing light passes. Reference numeral 27 denotes a black dot for shielding light, which is attached, for example, to a transparent flat plate.

28 is a mirror for changing the optical path, and 29 and 30 are relay lens groups. The perforated mirror 2 has the function of dividing photographing light and illumination light, and is arranged at the intersection of the optical axis of the photographing system and the optical axis of the relay lens group. The ring slit plate 26 and the pupil Ep of the eye to be examined are conjugate. Also sunspot 2
7 is conjugate with the surface of the fundus side of the crystalline lens Es when the angle of view is wide, and its size is the size that covers the area through which the photographing light (luminous flux reaching the film) passes through the lens surface on the fundus side. do. 21 to 30 above
, the objective lens 1, and the effective mirror 2 constitute an illumination system.

In the above configuration, the light beam emitted from the observation light source 21 is converged onto the ring slit plate 26 via the first and second condenser lenses 23 and 25, and illuminates the ring slit plate 26. The illuminated opening of the ring slit plate 26 becomes an annular secondary light source and emits a light beam, which is reflected by the mirror 28 and relay lens groups 29, 30.
The light is converged at the pupil Ep to form a secondary light source image almost on the perforated mirror 2, and is reflected there, and further forms a secondary light source image on the pupil Ep by the objective lens 1.
Uniformly illuminate Ef over a wide area. Scattered reflection occurs in the illuminated fundus Ef, and the general reflected light that passes through the aperture 2a of the perforated mirror 2 passes through the central region of the secondary light source image, that is, the light-shielding area (image 26a), and enters the subject's eye. exit, enter objective lens 1,
There, an image is formed and an intermediate image is formed. Next, the light beam passes through the central aperture 2a of the perforated mirror 2, enters the variable magnification imaging systems 3 to 8, converges and emerges there, is reflected by the flip-up mirror 17, and forms a fundus image near the field lens 18. From there, the fundus image can be observed through the eyepiece lens 20.

Next, 50 is the photographic field diaphragm, which uses a crimson diaphragm with a variable aperture diameter, as will be explained later. The function of this diaphragm is to cover the part of the fundus Ef that is illuminated by the illumination light with the image of the diaphragm, excluding the part to be photographed, to prevent harmful light from being mixed into the illumination light. Therefore, the position of this diaphragm must be conjugate with the fundus Ef, regardless of the field of view of the eye to be examined, and at the same time, the diaphragm blades must be opened and closed in accordance with the angle of view of the marginal shadow system.
Reference numeral 51 denotes a transmission member for the aperture opening/closing signal, which consists of a flexible tube that does not expand or contract and a flexible release cable 51a that slides inside the tube. You can assume that. A fixed metal fitting 52 fixes one end of the transmission member to the housing of the fundus camera. Reference numeral 53 denotes a cam surface contact, which is fixed to the tip of the cable 51. Note that both ends of the cable are made to have strong rigidity, so that the amount of feeding and feeding at one end is accurately transmitted to the other end. Reference numeral 54 denotes a circumferential cam plate, which is fixed to the zooming shaft 13 and rotates according to the zooming operation.The amount of cam displacement depends on the angle of view of the photographing system, that is, the range to be photographed on the fundus and the illumination diaphragm 58. Decide so that the range of light blocking is harmonious.

A movable plate 55 is movable in the optical axis direction of the illumination system while being guided by a guide mechanism (not shown), and the aperture 50 mentioned above is fixed thereon. This movable plate 55 is connected to the above-mentioned focusing lever 12 with a pin and a slotted hole, so when the focusing lens 3 moves during a focusing operation and the photographing system focuses on the fundus Ef, the aperture 55 moves with respect to the relay lens 30, the perforated mirror 2, and the objective lens 1 so as to be conjugate with the fundus Ef.

56 is the other end of the signal transmission member 51, and the movable plate 55
is fixed to the edge of the 57 is a connecting pin that connects the opening/closing member of the diaphragm 50 and the release cable 51a.

Figure 2 shows the diaphragm and connecting pin viewed from above, Figures 3 and 4 show the view from the optical axis direction, and Figure 3 shows the diaphragm blades corresponding to a wide angle of view. When the aperture is fully opened, FIG. 4 shows when the aperture blades are most narrowed down corresponding to the narrow angle of view.

In FIGS. 2 to 4, 59 is a sliding plate, which is provided with elongated holes 59a and 59b for guiding. Reference numerals 60 and 60' are guide screws which are screwed into the support of the aperture blades of the aperture 50. These guide screws 60 and 60' have elongated holes 59a.
and 59b are loosely fitted, and as a result, the sliding plate 59
becomes movable in a direction perpendicular to the optical axis X.

Reference numeral 61 denotes an opening/closing pin of the diaphragm 50, which fits into the hole 59c of the sliding plate 59, so that when the sliding plate 59 moves, the diaphragm blades 50a open and close. Reference numeral 62 denotes a lever, which is rotatably supported by a shaft 63, and this shaft 63 is implanted in the rising portion 55a of the movable plate 55. A long hole 62a is provided at one end of the lever 62, and a pin 64 is installed in the bent portion of the sliding plate 59.
and the elongated hole 62a constitute a pin/elongated hole connection. The other end of the lever 62 is bent and comes into contact with the aforementioned connecting pin 57. The sliding plate 59 and the movable plate 55 are arranged so that the lever 62 is always in contact with the connecting pin 57.
A tension coil spring 65 is attached to a part of the lever 62, and always biases the lever 62 counterclockwise.

Next, the removal of scattered light and reflected light by the crystalline lens Es will be explained.

In FIG. 1, 74 is a black point moving cam, which is fixed to the zooming shaft 13. The amount of displacement of the cam is determined according to the change in the angle of view, and if no harmful light is generated by the crystalline lens when the angle of view is narrow, the black dot 27 will come into contact with the light-shielding area 26a of the ring slit plate, and then the angle of view will change. To determine the position of a sunspot for each angle of view so that no harmful light is generated even if the image is enlarged, and illumination light is not needlessly blocked. 71 is a member equivalent to the signal transmission member 51, and 71a is a release cable. Reference numeral 72 indicates a fixing hardware for fixing the member 71, and 72a indicates an adjustment screw for adjusting the position of the tip 73 of the release cable. On the other hand, reference numeral 81 denotes a support cylinder, which is fixed to a housing (not shown), through which an illumination optical path passes, and to which a ring slit plate 26 is attached. A protruding flat plate 81a is provided on the outside of the cylinder 81, and a hole is bored in the protruding flat plate so that the end of the signal transmitting member 71 is inserted so that the other end 76 of the release cable 71a of the signal transmitting member 71 protrudes. The portion 75 is fixed to the flat plate 81a. 77 is a slide plate, and 78 is a slide shaft, both of which are integrated.The slide shaft 78 fits into guide holes 81b and 81c provided in a part of the support cylinder 81, and is parallel to the optical axis of the illumination system. It can be slid on. On the other hand, slide shaft 7
As shown in this figure and FIG. At this time, in order to place the black dot 27 inside the cylinder 81, the cylinder is provided with long grooves 81a and 81b parallel to the optical axis, and the legs 80a and 80 of the fixing hardware 80 are
b pass through the long grooves 81a and 81b, respectively. 7
9 is a return coil spring, and a plate 81 protrudes from the cylinder.
a and the sunspot fixing hardware 80, and the coil spring expands to close the legs 80a, 80b of the fixing hardware.
When the lens contacts one end of the long grooves 81a and 81b, the black dot 27 becomes conjugate with the fundus side of the crystalline lens Es, but the zooming shaft 13 rotates and the cam 74 rotates, and the tip 73 of the cable touches the circumferential surface of the cam 74. When the other end 76 of the cable is pushed in, the other end 76 of the cable protrudes by that amount and pushes down the slide plate 77 and the slide shaft 78, and as a result, the black dot fixing hardware 80 is pushed into the return spring 79.
move against. At this time, when the photographing system takes the narrowest angle of view, the cam lift of the cam 74 is maximum and the end 76 of the cable protrudes the most, so that the black dot 27 approaches the ring slit plate 26 most.

Next, in this figure and FIGS. 6 to 8, 82-2 is an exciter, and the exciter 82-2 is fixed to the filter frame 83. The filter frame 83 is engaged with the guide groove 81d of the support cylinder 81 and is slidable in the direction perpendicular to the plane of the first figure, and can be freely slid from the outside. −
1 (Figs. 6 and 8), and is inserted into the optical path so that the optical path length between the slit plate 26 and the condenser lens 25 does not change even when the exciter 82-2 is removed from the optical path. . Furthermore, 8
5 is a roller, which is rotatably supported by a bent portion of the slide plate 77; 84 is a cam plate, the side surface of which engages with a roller 85; The cam plate 84 is fixed to the filter frame 83 as shown in FIG. When the exciter 82-2 is inserted into the illumination optical path, the roller 85 contacts the trough 84a of the cam plate.
b.

Therefore, as shown in Fig. 6, when the parallel plate 82-1 is inserted and normal color photography is carried out, the position of the sunspot 27 is important, and the position of the cable is important depending on the angle of view of the photography system. The tip 76 protrudes, and the black spot 27
If the angle of view becomes the widest angle, the optical end 76 of the cable will be retracted the most, and the trough 84a of the cam plate 84 will come into contact with the roller 85. On the other hand, when the exciter 82-2 is inserted as shown in FIG. 7, and at the same time the barrier filter 88 shown in FIG. 1 is inserted in the photographing optical path, there is no need to shield the crystalline lens by sunspots. This is because, as is well known, the exciter and barrier filter have different transmission wavelength ranges, so even if the light that has passed through the exciter is reflected and scattered by the crystalline lens and mixed into the photographing light, it will be blocked by the barrier filter. . Therefore, as the filter frame 83 moves, the cam plate 84 pushes down the roller 85, and the slide plate 77
As the slide plate 78 is moved against the spring 79, the black spot 27 is brought closer to the ring slit plate 26. When the ridge 84b of the cam plate 84 and the roller 85 engage, the slide plate 77 moves the optical end 7 of the cable.
6, and even if the imaging system is set to a narrow angle and the tip 76 of the cable protrudes the most, it will not push the slide plate 77. Note that the sunspots can also be transferred in conjunction with the attachment of the barrier filter.

In the above configuration, as shown in FIG. 1, when the examiner looks through the eyepiece 20 to observe the fundus Ef and performs a focusing operation, the focus shaft 11 rotates, the focus lever 12 also rotates, and the focus is adjusted. Lens 3 moves. Note that during normal photographing, the exciter 82-2 and the barrier filter 88 are kept out of the optical path.

When the system focuses on the fundus of the eye, the examiner stops the focusing operation and keeps the focusing lens 3 at that position. At that time, focus lever 12
The moving plate 55 moves according to the rotation of the eye, and brings the diaphragm 50 into a conjugate relationship with the fundus Ef.

On the other hand, when a zooming operation is performed and the zooming shaft is rotated, the small gear 14 rotates, and the large gear 15 that meshes with this rotates to drive the cam tube 16, so the variable magnification lenses 7 and 8 have a predetermined relationship. Move with
The focal length, that is, the angle of view of the variable magnification imaging system is changed by a desired amount. At the same time, the cam plate 54 also rotates, and the contact 5
3 is pushed down or the contact 53 is allowed to rise, and the release cable 51a moves in the axial direction, so the connecting pin 57 also protrudes or retracts.

The lever 62 in FIG. 3 rotates according to the amount of movement of the connecting pin 57 in and out, and the sliding plate 59 also moves.
The opening/closing pin 61 also swings, and the aperture blades 50a are closed or opened.

Furthermore, when the cam plate 54 is rotated, another cam plate 74 is also rotated to push down the tip 73 or to raise the tip 73, thereby releasing the release cable 71a.
moves in the axial direction, so the other end of the cable 7
6 also protrudes or retracts. Therefore, the slide plate 77 and the shaft 78 move according to the amount of movement of the tip 76 in and out, and the black dot 27 occupies a position according to the angle of view.

In this way, when the imaging system is set to wide angle (short focal length), the aperture blades 50a are opened and the entire imaging field on the fundus is illuminated with illumination light, and the sunspot 27 prevents the generation of harmful light on the crystalline lens. However, when the angle is set to a narrow angle (long focal length), the aperture blades 50a are narrowed down and the periphery of the photographed area is covered with the shadow of the aperture, and the sunspot no longer blocks illumination light. Note that, also at each intermediate angle of view, the surrounding area of the continuously changing photographing angle of view is covered as the angle of view changes. Furthermore, as mentioned earlier, when the lens is mounted in a turret style, the angle of view changes discontinuously, so it goes without saying that the movement of the sunspot and the opening and closing of the aperture also become discontinuous.

Also, when taking fluorescent photographs, an exciter is attached to move the sunspot to a position where it does not block the illumination light.

According to the present invention described above, harmful light generated in the anterior segment and fundus of the eye to be examined can be removed at each angle of view during general photography, and also for special photography that requires a large amount of light such as fluorescence photography. This has the effect of making it possible to use the amount of illumination light as effectively as possible, thereby eliminating wasteful use of the amount of power supplied.

[Brief explanation of the drawing]

FIG. 1 is an optical cross-sectional view showing the embodiment, FIG. 2 is a top view showing the aperture drive unit, and FIGS. 3 and 4 are respectively,
FIG. 5 is a front view of the diaphragm drive unit, FIG. 5 is a perspective view of the black spot drive unit, FIGS. 6 and 7 are sectional views of the black spot drive unit, and FIG. 8 is a perspective view of the filter frame. In the figure, 3 is a focusing lens, 12 is a focusing lever, 27 is a focus, 50 is an aperture, 51 is an aperture opening/closing signal transmission member, 71 is a black spot movement signal transmission member, 77 is a slide plate, 78 is a slide shaft, 7
8 is a return spring, 82-2 is an exciter, 83 is a filter frame, 84 is a cam plate, and 88 is a barrier filter.

Claims (1)

[Scope of Claims] 1. A fundus that is equipped with a fundus illumination system and a fundus photography system and is capable of not only general photography but also fluorescence photography in which the wavelengths of the fundus illumination light and fundus photography light are separated, and variable magnification photography is possible for each. In the camera, a ring slit is installed in the fundus illumination system at a position optically conjugate with the anterior segment of the examinee's eye, a field diaphragm is installed at a position optically conjugate with the fundus of the examinee's eye, and the fundus illumination system during general photography. A light-shielding object is located inside the eye, and the ring slit image is formed in the vicinity of where the ring slit image is formed in the anterior segment of the subject's eye, and removes harmful light from the anterior segment. means for changing the light blocking area of the anterior segment of the eye to be examined by the light shielding object so as to increase the amount of illumination light; means for changing the aperture area of the field stop according to magnification change during general photography; A fundus camera comprising means for disabling a function of removing harmful light in the anterior segment of the subject's eye.