JP3490796B2 - Fundus camera - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera for photographing a fundus retina of an eyeball of a subject, and more particularly, to improve operations of alignment and working distance adjustment of a fundus photographing optical system. The present invention relates to a fundus camera designed for automation of operations.

[0002]

2. Description of the Related Art In recent years, fundus photography has become widely used in medical examinations because many useful medical findings such as arteriosclerosis and hypertension can be obtained. This fundus photography
The subject's eye is guided to a fixed position by a fixation target, illumination light is introduced into the fundus through the pupil of the subject's eye, and the fundus is photographed through the pupil. For this purpose, it is necessary to match the optical axis of the imaging device and the optical pupil with the optical axis of the eye to be inspected and the pupil, that is, to perform “alignment” and “working distance matching”. In the past, an examiner operated the position of the optical system in the XYZ directions with a joystick or the like, depending on the state of a finder image or a monitor image of a photographing device, to perform the “alignment” and “working distance adjustment”.

This "alignment" and "working distance adjustment"
The operation requires skill, and in order to improve the operability, a manual guide that also serves as "working distance adjustment" for the "alignment" has been proposed, for example, as shown in Japanese Patent Publication No. 56-5533. As for the photographing apparatus, as shown in Japanese Patent Publication No. 58-43090, alignment of a housing equipped with a photographing system in the vertical / horizontal direction and adjustment in the front / rear direction can be performed to align the eye with a fundus camera and the like and the eye to be examined. There has been proposed an ophthalmologic apparatus provided with an adjusting system capable of accurately adjusting a working distance which is an interval. Also, in order to improve the accuracy of automatic alignment and automatic focusing in the fundus camera, the fixation target, which is unnecessary during automatic alignment, and the projection index light for focusing are extinguished, and unnecessary during automatic focusing. Japanese Patent Application Laid-Open No. 5-95907 discloses that a light source for detecting a fixation target and a working distance is extinguished.

[0004]

However, not only the fundus camera which is normally used in the past, but also the fundus camera which can accurately perform the alignment and the working distance alignment of the improved type can be used. The adjustment and the adjustment of the working distance require a troublesome operation, and each of them requires considerable time and skill before shooting. Further, although a fundus camera equipped with the automatic alignment or automatic focusing device has been proposed, there is no one that continuously operates from automatic alignment to automatic working distance adjustment and further to automatic focusing.

The present invention has been made in view of the above circumstances, and improves troublesome operations such as "alignment" and "working distance adjustment" without requiring labor and learning, and the head of the subject is improved. We provide a fundus camera that can automatically perform alignment and working distance to the subject's eye simply by fixing the target to the jaw table and then fixing the target with the subject's eye and operating the machine. In addition, it is an object of the present invention to provide a fundus camera capable of continuously performing focusing and performing fundus imaging.

[0006]

In order to achieve the above object, in a fundus camera of the present invention, an illumination optical system for illuminating the fundus of an eye to be inspected and a fundus for illuminating the fundus by a television camera. A fundus photographing optical system for photographing, an anterior segment observation optical system capable of observing the anterior segment through an objective lens of the fundus photographing optical system, and an anterior segment observation optical system from two directions outside the optical axis Based on the alignment index projection means for alternately illuminating and projecting two alignment indexes on the surface, and the corneal reflection image position of the alignment index observed by the anterior ocular segment observation optical system, the fundus imaging optical system is moved toward the eye to be examined. And means for guiding.

As the two alignment indexes, the indexes are alternately projected from two directions that form an angle with the optical axes of the anterior ocular segment observing optical system and intersect each other such as orthogonal to each other. It is a good idea to be able to guide the reflected light of the alignment index from the cornea to the intersecting slit-shaped gates in the anterior segment observation screen by the anterior segment observation optical system while being arranged.

In order to detect the working distance of the fundus photographing optical system, the working distance detection index projection optical system for projecting the two alignment indexes and the index that alternately lights up toward the eye to be examined, and the working distance detection. Working distance detection means for detecting the working distance based on the reflected light from the cornea of the index, and means for guiding the fundus imaging optical system in the direction of the eye to be examined until the working distance detection means detects the corneal reflected light of the working distance detection index. It is effective to provide the fundus camera.

[0009]

The fundus camera of the present invention, having the structure described in claim 1, alternately lights and projects two alignment indexes on the ocular spherical surface from two directions outside the optical axis of the anterior ocular segment observation optical system. Then, when the anterior segment of the eye is observed by the anterior segment observation optical system through the objective lens of the fundus imaging optical system, the interference of each alignment index light is eliminated and the cornea is located at two positions outside the center of the cornea on the anterior segment image. A light spot that is a reflection image can be formed. Therefore, based on the position of the corneal reflection image of the alignment index on the observed anterior segment image, it is possible to easily and automatically perform the alignment by the means for guiding the fundus imaging optical system in the direction of the subject's eye, and the alignment is performed with a simple configuration. Can easily and automatically perform fundus imaging.

As the two alignment indexes, the indexes are arranged so as to be projected alternately from two directions that form an angle with the optical axes of the optical axes of the anterior segment observation optical system and intersect with each other. By allowing the reflected light of the alignment index from the cornea to be guided to the intersecting slit-shaped gates in the anterior ocular segment observation screen, the two alignment indices are reliably projected onto the cornea, and the alignment index from the cornea Alignment can be performed easily and accurately using the slit-shaped gate that intersects the reflected light as a guide. In this case, the guidance can be easily performed by setting the intersecting angles of the intersecting planes and the intersecting slits at right angles, but it is not necessarily required to be at right angles and any intersection angle can be used.

The retinal camera is provided with a working distance detection index projection optical system for projecting an index that alternately lights up with the two alignment indexes toward the eye to be examined, and the working distance detection index is provided by the working distance detection means. A means for guiding the eye fundus imaging optical system in the direction of the eye to be examined until the working distance detecting means detects the corneal reflected light of the working distance detection index so as to detect the working distance based on the reflected light from the cornea. By doing so, it is possible to prevent the three index lights of the two alignment indexes and the working distance detection indexes from interfering with each other,
Even during the "working distance adjustment" operation, the alignment can be simultaneously controlled to continue the alignment (following the alignment), and the working distance can be automatically adjusted.

[0012]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an optical path diagram of the embodiment, FIG. 2 shows an irradiation state of two alignment index lights on an eye spherical surface at the time of alignment, and FIG. 3 shows alignment on an imaging screen at the time of alignment. A state in which the light spot, which is the index image, is moved to perform alignment is shown.

In FIG. 1, an illumination optical system adapted to illuminate the fundus of the eye 1 to be inspected, and a fundus photographing optical system capable of observing or taking a photograph of the fundus by the television camera 10 based on the illumination light irradiating the fundus. System, the anterior ocular segment observation optical system that allows the anterior ocular segment to be observed by the TV camera 27 through the objective lens 5 of the fundus photographing optical system, and the eyeball from two directions outside the optical axis of the anterior ocular segment observation optical system. Alignment index projection means for lighting and projecting two alignment indexes on the surface 2;
The optical axis 4 of the fundus photographing optical system is passed through the oblique optical axis and
Working distance detection index projection optical system for projecting an index that alternately lights up with the alignment index of the eye toward the eye to be examined, and the reflected light from the cornea of the working distance detection index to detect the fundus imaging optical system and the pupil of the eye to be examined. There is shown a photographing system 3 including a working distance detection optical system for detecting a working distance, which is a distance to the eye, and a focusing index projection optical system for projecting a focusing index on the fundus of the eye. Reference numeral 3 is moved by a drive mechanism to be described later in each of three directions, that is, the Z direction, which is the direction of the optical axis 4 of the fundus photographing optical system, and the X and Y directions orthogonal to the optical axis.

As a light source for illuminating the fundus of the eyeball 1, a strobe discharge tube 11 used for photographing a fundus retina and a halogen lamp 38 used for focusing of a fundus photographing optical system are used.
Condensing lens that emits light from the common illumination optical axis 16
After passing through 20, the light is reflected by a perforated mirror 6 (the outer shape is circular due to the centering of the hole) and passes through the objective lens 5 along the optical axis 4 so that the corneal reflected light is excluded and enters the eye 1 to be inspected. Has become.

Visible light emitted from the stroboscopic discharge tube 11 for photography is focused on the position of the circular slit 14 by the condenser lenses 12 and 13, and then passes through the circular slit 14 to pass through the mirror 15.
Is reflected on the illumination optical axis 16 by being bent by the flat glass 17, condenser lens 18, half mirror 19, condenser lens 20.
The image of the circular slit which is focused in the vicinity of the perforated mirror 6 is formed on the perforated mirror 6 and is reflected by the mirror 6, and the objective of the optical system on the optical axis 4 of the fundus photographing optical system. The light passes through the lens 5, converges at the corneal vertex position, passes through the pupil position of the eyeball 1 (the position of the iris diaphragm), and irradiates the retina surface of the fundus of the eyeball 1. The positions of the strobe discharge tube 11, the circular slit 14, and the apex of the cornea of the eyeball 1 are in a conjugate relationship. That is, the illumination light enters the eye to be inspected only from the ring-shaped passage of the circular slit 14 and illuminates the fundus through the pupil. At this time, the reflected light from the center of the cornea is cut off and does not directly enter the objective lens.

In the fundus photographing optical system, an objective lens 5 is disposed on the optical axis 4 of the fundus photographing optical system which should be located on the eye axis so as to face the eye 1 to be examined and form an optical pupil in the pupil portion of the eye. It is set up. Then, a perforated mirror 6, a focus lens 7, and a relay lens 8 are sequentially arranged at predetermined positions on the optical axis 4, and a movable focus lens 7 (focus index projection optical described later) is provided. When the fundus image is focused and formed on the CCD light-receiving surface 9 on the front of the rear TV camera (fundus color imaging TV) 10 by adjusting the position of the movable part of the system) The reflected light from the fundus of the eye enters the CCD light receiving surface 9 to detect the focus. Then, the index light for autofocusing is turned off and the strobe discharge tube 11 emits light to photograph a fundus image. In the present embodiment, the fundus focusing detection and the fundus imaging are performed by the CCD 9 of the same TV camera 10. However, the light receiving element for the fundus focusing detection uses the optical path of the fundus photographing optical system behind the focus lens 7. Alternatively, the focus may be detected by the focus detection CCD or PSD arranged on the branched optical axis.

In order to make index light for autofocus incident on the eye 1 to be inspected, a focusing index branched laterally in parallel to the optical axis of the fundus photographing optical system with respect to the half mirror 19 provided on the illumination optical axis 16. Converging lens at predetermined positions on the optical axis of the projection optical system
44, a pair of left and right fixation targets 43L, 43R, split prism 4
2, a projection lens 41, an autofocus index slit 40, a condenser lens 39, and a halogen lamp 38 which is an autofocus index light source are arranged. The light from the halogen lamp 38 integrally forms a movable part of the focusing index projection optical system, and works in conjunction with the focus lens 7 on the optical axis 4 of the fundus photographing optical system. Then, after passing through the focusing lens slit 40, the projection lens 41, the split prism 42, the condenser lens 44, the half-focusing mirror 19 reflects the focusing target light, and the focusing lens 20 is placed on the illumination optical axis 16. After that, the light is reflected by the perforated mirror 6, passes through the objective lens 5 on the optical axis 4 of the fundus photographing optical system, and the cornea reflected light is excluded and enters the eye 1 to be inspected.

The pair of left and right fixation targets 43L and 43R presents the subject with either the left or right fixation target corresponding to the subject's eye from the time of alignment to the time of photographing, and at the time of focusing and strobe light. At the time of photographing by light emission, it is moved together with the movable portion of the focusing index projection optical system that works in conjunction with the focus lens 7 and presented to the subject so that it can be seen well when focused.

Further, in order to observe the anterior segment in order to know the alignment state of the ocular spherical surface 2, an anterior segment observation optical system capable of observing the anterior segment through the objective lens 5 of the fundus photographing optical system is provided. It is provided. That is, an image from the ocular spherical surface 2 is obtained by a small half mirror 23 which is arranged at a predetermined position close to and behind the perforated mirror 6 on the optical axis 4 of the fundus photographing optical system so as to intersect the optical axis 4 by 45 °. The light beam is bent at a right angle to the optical axis, and the alignment monochrome TV camera 27 of the alignment through the lens 25 for anterior segment photographing arranged on the optical axis 24 of the folded anterior segment observation optical system. CCD
An image of the anterior segment is formed on the light receiving surface 26.

Further, in order to alternately turn on and project the two alignment indexes on the ocular spherical surface 2 from two directions outside the optical axis of the anterior ocular segment observation optical system, the near infrared light which is the alignment index light is emitted. Two diodes are provided at predetermined positions. That is, on the front side of the objective lens 5 of the fundus photographing optical system, on a plane orthogonal to the X and Y directions, including the fundus photographing optical optical axis 4 which also serves as the optical axis (front part) of the anterior segment observation optical system. From two directions forming an angle with the optical axis 4, the optical axes of the light emitting diodes are directed to the eye spherical surface 2 of the eye 1 to be inspected, and two infrared light emitting diodes 21 and 22 are arranged. Are alternately projected onto the eye spherical surface 2 of the eye 1 to be inspected. FIG. 2 shows an anterior ocular segment image illuminated by infrared light emitting diodes 21 and 22 arranged on two horizontal and vertical orthogonal planes including an observation or photographing optical axis 4 on an eye spherical surface 2 of an eye 1 to be examined. The state of observation (from the V direction) through the objective lens 5 is shown.

As a result, the two alignment index lights for the X and Y directions are emitted from the light emitting diodes 21 and 22 to the ocular surface 2 of the eye.
When the light is irradiated onto the eye, the reflected light can be received and detected on the CCD light receiving surface 26 of the monochrome television camera 27 for the eyeliment together with the anterior segment image. In detecting the alignment index light by the CCD light receiving surface 26, in order to eliminate mutual interference with the working distance detection index light described later, the two alignment index lights are alternately turned on with the working distance detection index light. The alignment in the XY directions is detected in synchronization with the lighting of. (See Figure 5).

In order to detect the working distance of the fundus photographing optical system with respect to the eye 1 to be inspected, the working distance detecting index projection is performed as if it has an optical axis 31 'inclined about 45 ° with respect to the optical axis 4 of the fundus photographing optical system with respect to the ocular spherical surface 2. An optical system is provided, and a working distance detecting optical system is provided on the optical axis 35 in a symmetrical direction on the opposite side of the fundus photographing optical system optical axis 4, and detects corneal reflected light of working distance detecting index light. Then, the working distance of the fundus photographing optical system is detected.

That is, an infrared light emitting diode (infrared LED) 31 which is a light source of the working distance detection index is provided at a predetermined position on the optical axis 31 'of the working distance detection index projection optical system,
The infrared light from the infrared light emitting diode 31 is collected by a condenser lens.
32, the working distance detection index slit 33, and the projection lens 34 are incident on the eye spherical surface 2, and the reflected light from the eye spherical surface (cornea) 2 travels on the optical axis 35 of the working distance detecting optical system and is condensed. lens
The light enters the light receiving element (PSD) 37 for detecting the working distance via 36 and detects the working distance of the fundus photographing optical system.
The infrared light emitting diode (infrared LED) 31 for the working distance detection index is turned on at the time of alignment at the beginning of photographing, as described above, the two infrared light emitting diodes 21 for the alignment index for the X direction and the Y direction. , 22 lights up alternately. That is, XY in FIG.
As shown in the timing chart for the XY detection CCD 26 for lighting two alignment indexes and working distance detection indexes, the three index lights of the two alignment indexes and the working distance detection indexes can be prevented from interfering with each other. Even during the operation for adjusting the working distance, it is possible to adjust the working distance of the fundus imaging optical system while simultaneously controlling the alignment and continuing the alignment.

Next, a circuit for operating the photographing system 3 will be described with reference to the block diagram shown in FIG. Infrared light emitting diode (infrared LDE) for two alignment indexes
The reflected light from the eye spherical surface 2 of the alignment index light by the alternating lighting of 21, 22 (alternating simultaneously with the working distance detection index) is imaged by the TV camera (monochrome TV camera for alignment) 27 of the anterior ocular segment observation optical system. CCD light receiving surface
The image-receiving signal obtained by forming an image on 26 is an image input / output control circuit.
Enter in 45. On the screen of the monitor display 47 which receives the video signal from the control circuit 45, two light spots due to the corneal reflected light of the two infrared rays for alignment from the eye spherical surface 2 are displayed together with the anterior segment image. You can check the alignment status in the first half of the operation. in this case,
The anterior segment image can be observed with room light, and may be illuminated with infrared light as necessary.

In the XY direction position detection control circuit 49 which receives the electric signal from the image input / output control circuit 45, the image pickup screen 30
Positions of two light spots due to upper corneal reflected light (see FIG. 3),
That is, a light spot 21 'due to corneal reflected light of infrared light from the infrared light emitting diode 21 for the alignment index for the X direction, and an infrared light emitting diode for the alignment index for the Y direction.
Position of light spot 22 'due to corneal reflected light of infrared light from 22 in X / Y directions with respect to optical axis of anterior ocular segment observation optical system (corresponding to position in X / Y directions with respect to optical axis 4 of fundus photographing optical system) To detect.

By the control signal by this position detection, the two light spots 21 'and 22' on the image pickup screen 30 are changed to the image pickup screen 30.
So as to come to the slit-shaped gates 28 and 29 which are electrically formed in the X-Y direction, that is, the light spot 21 'of the alignment index for the X-direction is the vertical slit-shaped gate 28.
In order to guide the gantry by driving the XY axis drive mechanism 50 of the gantry equipped with the imaging system 3 so that the light spot 22 'of the Y-direction alignment index comes to the slit-shaped gate 29 in the horizontal direction. (See Figure 3).

When the XY direction position detection control circuit 49 detects that each light spot on the image pickup screen falls within a narrow predetermined range surrounding the center of the screen, for example, the control circuit
An electric signal from 49 is input to the working distance detection control circuit 51, the Z-axis drive mechanism 52 is operated by the drive signal from the control circuit 51, and the gantry equipped with the imaging system 3 is moved from the initial standby position to the eyeball of the eye to be inspected. The forward movement is started in the optical axis direction (Z direction) of the fundus photographing optical system toward the surface 2, and at the same time, the XY axis drive mechanism 50 is driven, and the optical point 21 'of the alignment index for the X direction is a vertical slit. To the gate 28, the light spot 22 'of the alignment index for the Y direction is a horizontal slit gate.
Track each light spot so that it will come to 29 respectively.

In this way, the Z-axis is driven while tracking each light spot to the slit-shaped gate on the image pickup screen,
Indicator for working distance detection when the light receiving element (PSD) 37 of the working distance detecting optical system passes through the slit 33 from the infrared light emitting diode 31 while the photographing system 3 is moving forward in the optical axis direction (Z direction) of the fundus photographing optical system. When detecting the light, the working distance is detected by the working distance detection control circuit 51 by the signal from the light receiving element 37 (the optical pupil of the objective lens 5 of the fundus photographing optical system is the eye 1 to be examined).
(In a state of coincidence with the pupil position of No. 1), the Z-axis drive mechanism 52 is stopped by the signal from the working distance detection control circuit 51, and at the same time, the XY-axis drive mechanism 50 is stopped by the signal from the XY direction position detection control circuit 49 and the imaging system is operated. The mount of No. 3 stops moving.

At this time, the halogen lamp which is the autofocus index light source is turned on, the focus detection circuit 53 is operated, and the focus control mechanism 54 is driven by the signal from the focus detection circuit 53 to drive the fundus photographing optical system. In conjunction with the focus lens 7 on the optical axis 4, the halogen lamp 38, the condenser lens 39, the autofocus index slit 40, the projection lens 41, the split prism 4
2. Focusing is performed by moving the movable parts of the focusing index projection optical system consisting of the fixation targets 43L and 43R on the respective optical axes.

Focusing is performed in this way, and the reflected light of the focusing index from the fundus is received by the television camera 10 for imaging the fundus of the fundus photographing optical system, and the received signal of the focusing index from the television camera 10 is received. It is input to the focus detection circuit 53 via the image input / output control circuit 45, and the focus of the fundus image is detected in the circuit 53. Simultaneously with this focus detection, the halogen lamp 38 of the focus index projection optical system is turned off to turn off the focus index, and the strobe discharge tube 11 is caused to emit light by the signal from the focus detection circuit 53 via the strobe light emission control circuit 55. At least, a fundus image is captured on the light receiving surface 9 of the television camera 10. And tv camera
The image signal of the fundus from 10 is recorded (written) in the frame memory 46 via the image input / output control circuit 45, and the fundus image is displayed on the monitor display 47. In addition, the fundus image is read from the frame memory 46 by the image input / output control circuit 45 as necessary, and then the video printer
It can be launched from 48, and an image print of the subject's eye can be attached to the chart.

When the above photographing is completed, the photographing system 3 is automatically returned to the standby position. That is, at the end of photographing, the XY-axis drive mechanism 50 is reversely driven from the image input / output control circuit 45 via the XY-direction position detection control circuit 49, and
The Z-axis drive mechanism 52 is reversely driven by the signal from the direction position detection control circuit 49 via the working distance detection control circuit 51, and the photographing system 3 is set to the axial direction (Z direction) of the optical axis 4 of the fundus photographing optical system. It is moved in a direction (XY direction) orthogonal to the axis to return to the initial state, and the photographing system 3 is put in a standby state.

Next, the operation procedure of the fundus camera according to the present invention will be described with reference to the flowcharts shown in FIGS. First, when the power button is turned on and the photographing button of the fundus camera in the standby state is pressed, an external image by the anterior ocular segment observation optical system is displayed on the monitor display 47. The examinee fixes his / her head on the jaw stand and looks at the fixation target through the objective lens 5 according to the doctor's instruction. At this time, the jaw base detects whether the eye to be inspected is the right eye or the left eye based on the relative position of the jaw base with respect to the objective lens 5, and a pair of left and right pairs provided in the focus index projection optical system is detected by a signal from the jaw base. The fixation target 43L, 43R is switched to one of the left and right fixation targets (LEDs) corresponding to the eye to be inspected and turned on. Next, the doctor operates the jaw stand, adjusts the monitor display 47 so that the anterior segment of the subject's eye is displayed, and presses the photographing button again.

By this second button pressing operation, the alignment index infrared light emitting diode 21 for the X direction and the alignment index infrared light emitting diode 22 for the Y direction as the alignment index, and the working distance detection index as the working distance detection index. The infrared light emitting diodes 31 and the three infrared light emitting diodes are alternately turned on (see FIG. 5).
Next, the Z-axis is displayed until the image (light spot) of the alignment index light by the reflected light of the two alignment index lights from the cornea 2 can be recognized in the anterior segment image displayed on the imaging screen 30 of the alignment TV camera 27. To drive the photographing system 3 forward in the Z direction.

When the two images (light spots) 21 'and 22' of the alignment index light are recognized on the image pickup screen 30 of the alignment TV camera 27, the image pickup screen is automatically displayed according to the position of the light spot. The X-axis and Y-axis are driven and the imaging system 3 is moved with respect to the subject's eye until it enters a predetermined range of the central X-Y alignment. Then, this state is displayed on the screen of the monitor display 47.

In this way, the light spot of the alignment index light
When 21 'and 22' come within a predetermined range at the center of the imaging screen, the light spot 21 'of the alignment index light for the X direction is within the predetermined range.
Is the vertical slit-shaped gate 28, and the light spot 22 'of the alignment index light for the Y direction is the horizontal slit-shaped gate 28.
While performing alignment by tracking the light spot so as to come to 29, the Z axis is driven to advance the photographing system 3 in the Z direction until the working distance detection control circuit 51 detects the working distance detection index image.

During the forward movement of the photographing system 3 in the Z direction, when the working distance detection control circuit 51 detects the working distance detection index image (corneal reflected light) and the working distance is detected, the X-axis / Y
The driving operation of the axis / Z axis is stopped, the infrared light emitting diodes 21 and 22 for the alignment index and the infrared light emitting diode 31 for the working distance detection index are turned off, and the automatic focus index light source of the focusing index projection optical system is used. A halogen lamp
38 is turned on, and the focus lens 7 and the halogen lamp 38 integrally linked with the focus lens 7, the condensing lens 39, the autofocus index slit 40, the taking lens 41, the split prism 42, the fixation targets 43L, 43R And a movable part composed of the moving parts are moved and scanned on the respective optical axes, and the focus of the fundus image is detected.

When the focus is detected, the halogen lamp 38 for the auto focus indicator is turned off, the stroboscopic discharge tube 11 emits light, and the fundus image is photographed by the color television camera 10 for photographing the fundus.
The photographed fundus image is recorded in the frame memory 46 and displayed on the monitor display 48, and then the photographing system 3 returns to the initial standby position and enters the standby state.

In this embodiment, the television camera 10 for photographing the fundus is used to receive and observe the auto-focus index light for detecting the focus, but the optical path (optical axis) of the fundus photographing optical system is used. Condenser lens and CCD on the optical path (optical axis) branched from
It is also possible to arrange a camera or PSD to receive and observe the auto-focus index light to detect the focus. Further, when operating the fundus camera, the image from the television camera of the anterior ocular segment observing optical system may be displayed on the monitor by pressing the photographing button even after the head of the subject is fixed to the jaw stand.

[0039]

According to the fundus camera of the present invention as set forth in claim 1, two alignment indexes are alternately turned on and projected on the ocular spherical surface from two directions outside the optical axis of the anterior segment observation optical system, The anterior segment can be observed coaxially with the fundus imaging optical system through the objective lens of the fundus imaging optical system, and the fundus imaging optical system is covered based on the corneal reflection image position of the alignment index observed by the anterior segment observation optical system. Since the light is guided in the eye examination direction, it is possible to eliminate the interference between the alignment index lights and perform the alignment easily and automatically with a simple configuration to perform fundus imaging.

According to the second aspect of the present invention, in the fundus camera, two alignment indexes are surely projected onto the cornea, and the reflected light thereof is used as a guide through the intersecting slit-shaped gates in the anterior segment observation screen. It is possible to easily guide the fundus photographing optical system in the direction of the eye to be aligned.

According to the third aspect of the invention, in the fundus camera, “working distance adjustment” is performed without interfering with each other by the three index lights of the two alignment indexes and the working distance detection index. Alignment can be controlled simultaneously during operation to continue alignment,
The working distance adjustment can be easily automated.

[Brief description of drawings]

FIG. 1 is an optical path diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a state of irradiation of two alignment index lights onto an ocular spherical surface during alignment.

FIG. 3 is a diagram showing a moving state of an alignment index image on an imaging screen during alignment.

FIG. 4 is a block diagram of an embodiment of the present invention.

FIG. 5 is a timing chart of lighting of the alignment index and lighting of the working distance index.

FIG. 6 is a flowchart showing a procedure of fundus imaging.

FIG. 7 is a flowchart showing a procedure following FIG.

[Explanation of symbols]

1 ... Eyeball, 2 ... Eye spherical surface (cornea), 3 ... Imaging system, 4
Optical axis of fundus photographing optical system, 5 Objective lens, 6 Perforated mirror, 7 Focus lens, 9 CCD light receiving surface, 10 Color television camera for fundus imaging, 11 Strobe discharge tube, 14 Circular shape Slit, 19 ... Half mirror,
21,22 ... Infrared light emitting diode for alignment index,
23 ... Half mirror, 26 ... CCD light receiving surface, 27 ... Alignment television camera, 28, 29 ... Slit gate, 30 ... Imaging screen, 31 ... Infrared light emitting diode for working distance detection index, 37 ... Photosensitive element for working distance detection , 38
… Halogen lamps for auto focus indicators, 43L, 43R… Fixation targets, 46… Frame memory, 47… Monitor display, 49…
XY direction position detection control circuit, 50 ... XY axis drive mechanism, 51
… Working distance detection control circuit, 52… Z-axis drive mechanism, 53…
Focus detection circuit, 54 ... Focus control mechanism, 55 ... Strobe light emission control circuit.

Continuation of the front page (56) Reference JP-A-6-7302 (JP, A) JP-A-7-88082 (JP, A) JP-A-5-146410 (JP, A) JP-A-5-95907 (JP , A) JP 56-5533 (JP, B2) JP 58-43090 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 3/10-3/18

Claims (3)

(57) [Claims] 1. An illumination optical system for illuminating a fundus of an eye to be inspected, a fundus photographing optical system for photographing a fundus by a television camera on the basis of illumination light irradiating the fundus, and an objective lens of the fundus photographing optical system. An anterior segment observation optical system capable of observing the eye part, and an alignment index projection means for alternately lighting and projecting two alignment indices on the eye spherical surface from two directions off the optical axis of the anterior segment observation optical system, Based on the corneal reflection image position of the alignment index observed with the anterior segment observation optical system,
A fundus camera, comprising: means for guiding the fundus photographing optical system in the direction of the eye to be examined. 2. The two alignment indexes are arranged so as to alternately project from two directions forming an angle with the optical axes on a plane including the optical axis of the anterior segment observation optical system and intersecting each other, 2. The fundus camera according to claim 1, wherein the reflected light of the alignment index from the cornea can be guided to the intersecting slit-shaped gates in the anterior segment observation screen. 3. A working distance detection index projection optical system for projecting an index, which alternately lights up with the two alignment indexes, toward an eye to be examined in order to detect a working distance of a fundus photographing optical system, and a working distance detection index. A working distance detecting means for detecting a working distance based on the reflected light from the cornea and a means for guiding the fundus photographing optical system toward the eye to be examined until the working distance detecting means detects the corneal reflected light as a working distance detection index. The fundus camera according to claim 1 or 2, characterized in that.