JP2005137584A - Fundus camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fundus camera for imaging excellent images of a fundus oculi without influences of flare, smear, and blooming. <P>SOLUTION: The images of the fundus oculi are imaged by a TV camera 20A that uses a CCD as an image pickup device. A controlling part 40 detects whether a light shielding point 16b of a small diameter is used for imaging. If the controlling part 40 detects the use of the light shielding point 16b, the controlling part 40 transmits the data of the fundus oculi to a masking processing part 47 and controls the masking processing part 47 to perform the masking processing on the image of the fundus oculi. The masking processing is especially performed on a region corresponding to reflected light at a lens of eye. The image is stored in an image memory part 41 and is displayed on a display part 42. If the controlling part 40 detects that the light shielding point 16b is not used, the image is displayed on the display part 42 as it is without performing masking processing. Incident light of the illuminating light reflected at a cornea is shielded by a sight throttle 27. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fundus camera for photographing a fundus image of a subject's eye, and more particularly to a fundus camera configured to photograph a fundus image using an image sensor such as a CCD.

  Conventionally, a technique of inspecting the state of the fundus by taking a fundus image of the eye to be examined with a fundus camera and examining the fundus image has been widely used. For example, as shown in Patent Document 1 below, an optical system of a previous fundus camera forms a fundus image with an objective lens and again forms an image with a focusing lens and relays it to a TV camera via a relay lens. It was configured to take a fundus image.

  Various needs have arisen when examining the fundus in actual medical practice. For example, in order to examine the fundus in more detail, a fundus camera has been proposed that can provide a fundus camera with two types of imaging magnifications of low magnification and high magnification by providing an optical system that can change the photographing angle of view (for example, Patent Document 2). Also, a fundus camera in which the illumination system aperture (light-shielding point) and imaging field aperture can be varied in order to capture the fundus image of the eye to be inspected, which can ensure only a small pupil diameter (called small pupil imaging). Has been proposed (see, for example, Patent Document 3). According to this fundus camera, small pupil imaging can be performed without changing the imaging magnification. Furthermore, in order to prevent image deterioration due to flare generated around the fundus image due to corneal reflection of illumination light, a fundus camera provided with a mask that restricts the field of view by shielding the flare has been proposed.

  In recent years, with the dramatic increase in the number of pixels of a charge-coupled device (CCD), fundus cameras that capture fundus images with a CCD camera have been developed and become popular. Patent Document 4 discloses, as an example of such a fundus camera, a structure in which a fundus image captured by a CCD camera is electronically variable.

  As a conventional fundus camera equipped with a CCD, various pattern mask images are stored in advance, a pattern mask image is selected in accordance with optical system information such as information relating to small pupil photography, and the pattern mask image is converted into a fundus image. There has been proposed a fundus camera configured to be combined and displayed. (Patent Document 5).

  However, since such a CCD-equipped fundus camera is not provided with a mask for limiting the field of view, the reflected light from the cornea of the illumination light is directly incident on the CCD imaging surface, resulting in smearing or blooming. It will deteriorate. Here, “smear” is a level in which the amount of charge that is photoelectrically converted during vertical transfer cannot be ignored when there is a very bright subject in the imaging area. This is a phenomenon where whitish streaks appear. In addition, “blooming” is a phenomenon in which light is blurred as a result of excessive charge generated when strong light enters the CCD imaging surface overflowing to the pixels around the pixel. is there.

  The captured image is also affected by flare caused by scattering and reflection of illumination light on the crystalline lens of the eye to be examined. The effect of this flare is small compared to the effect of corneal reflection described above. In fact, the refractive index of the cornea is about 1.376, and the refractive index of air is about 1.0, so the difference in refractive index at the interface is about 0.376, whereas the refractive index of the lens is Since the refractive index of the vitreous body is approximately 1.386 and the refractive index of the vitreous body is approximately 1.336, the difference in refractive index at the boundary surface is approximately 0.05. Therefore, the reflected light on the corneal surface is about 7.5 times stronger than the reflected light on the boundary surface between the crystalline lens and the vitreous body. Here, the boundary surface of the rear surface of the crystalline lens is a target for consideration of flare generation, and the boundary surface with the anterior chamber on the front surface of the crystalline lens is not the target.

Japanese Patent No. 3078030 ([Claims], paragraph [0020], FIG. 3) Japanese Patent No. 3359126 ([Claims], paragraphs [0007]-[0010]) Japanese Patent No. 3243272 ([Claims], paragraph [0009]) Japanese Patent Application Laid-Open No. 11-28189 ([Claims], paragraph [0010]) Japanese Patent Application Laid-Open No. 2003-204939 ([Claims], paragraphs [0026]-[0028])

  The present invention has been made in view of the above circumstances, and in fundus imaging using an imaging means equipped with a CCD, a good fundus image without the influence of flare caused by reflected light from the crystalline lens of the eye to be examined can be easily obtained. An object of the present invention is to provide a fundus camera capable of photographing. It is another object of the present invention to provide a fundus camera that can easily take a good fundus image free from the effects of smear and blooming caused by corneal reflection light.

  Furthermore, another object of the present invention is to provide a fundus camera capable of suitably performing high-magnification imaging and small pupil imaging with a simple configuration.

  In order to achieve the above object, the invention according to claim 1 is a ring slit that is arranged at a position conjugate with the anterior eye portion of the eye to be examined and has illumination light that illuminates the fundus of the eye to be examined having a cross-sectional ring shape. An illumination system including a member that is disposed at a position different from the ring slit and that configures a light shielding point that can change a region that shields the illumination light; an objective lens that is disposed facing the eye to be examined; and A first imaging system including an imaging aperture disposed at a position conjugate with the pupil of the eye to be examined, and imaging the reflected light of the illumination light from the fundus through the objective lens and the imaging aperture; and the fundus And a second imaging system including an imaging unit configured to receive the reflected light by a CCD and capture a fundus image of the eye to be examined, and an area of the illumination light shielded by the light shielding point. In response to changes It is a fundus camera according to claim which comprises a masking means being operable to electrically masking a partial region of the reflected light received by the image pickup means.

  In order to achieve the above object, the invention according to claim 2 is the fundus camera according to claim 1, wherein the first imaging system is arranged at a position conjugate with the fundus, and the fundus In order to limit an imaging field of view of the image, the image capturing apparatus further includes a field stop that blocks a partial area of the reflected light, and the second imaging system relays the reflected light whose partial area is blocked by the field stop And a relay lens for forming an image on the imaging surface of the imaging means.

  In order to achieve the above object, the invention according to claim 3 is the fundus camera according to claim 1, wherein the second imaging system is arranged in the vicinity of the imaging surface of the imaging means. It further includes a shielding diaphragm for shielding the reflected light of the illumination light by the cornea of the eye to be examined.

  In order to achieve the above object, a fourth aspect of the present invention is the fundus camera according to any one of the first to third aspects, wherein the masking means is shielded by the light shielding point. In response to the change in the area of the illumination light to be reduced, control is performed so as to electrically mask a partial area of the reflected light received by the imaging means.

  In order to achieve the above object, a fifth aspect of the present invention is the fundus camera according to the fourth aspect, wherein the magnification for changing the photographing magnification of the fundus image photographed by the imaging means is provided. And a member constituting the light shielding point so as to reduce a region of the illumination light shielded by the light shielding point in response to the photographing magnification by the magnification changing means being changed to a predetermined magnification or more. And a control means for controlling.

  In order to achieve the above object, the invention according to claim 6 is the fundus camera according to claim 4, wherein the photographing field angle is set small in order to photograph the fundus image of the eye to be examined having a small pupil diameter. A small pupil mode setting means for setting to a small pupil photographing mode for performing photographing, and the light shielding point shields light in response to the small pupil photographing mode being set by the small pupil mode setting means. And a control means for controlling a member constituting the light shielding point so as to reduce the area of the illumination light.

  According to the first aspect of the invention, in response to the change of the area of the illumination light shielded by the light shielding point, the masking process is electrically performed on the partial area of the reflected light received by the imaging unit. Applied. Therefore, an electrical masking process can be performed on a region where flare occurs in the fundus image when the light shielding point is changed, and a good fundus image can be taken.

  According to the second aspect of the present invention, since the field stop is arranged in the first imaging system, the corneal reflected light incident on the imaging system is reflected by the cross-sectional ring-shaped illumination light reflected by the eye cornea. Can be shielded. Therefore, it is possible to remove the influence of smear and blooming caused by the corneal reflection light. Further, flare caused by reflected light from the crystalline lens of the eye to be examined can be dealt with by masking means.

  According to the third aspect of the present invention, the corneal reflection light can be shielded by the shielding diaphragm disposed in the vicinity of the CCD, so that the influence of smear and blooming caused by the corneal reflection light can be eliminated. Further, flare caused by reflected light from the crystalline lens of the eye to be examined can be dealt with by masking means.

  According to the fourth aspect of the present invention, when the area of the illumination light shielded by the light shielding point is changed to be small, the cross-sectional shape of the illumination light becomes a thick ring shape, and flare is likely to occur in the periphery of the photographed image. However, since the masking process is automatically performed and the influence of the flare is removed, a good fundus image can be obtained.

  According to the fifth aspect of the present invention, since the masking process is automatically performed in response to the photographing magnification being changed to a high magnification, a good configuration with no flare can be obtained with a simple configuration even when photographing at a high magnification. A fundus image can be obtained.

  According to the sixth aspect of the invention, in response to the setting of the small pupil photographing mode, the light shielding area of the illumination light by the light shielding point is controlled to be small, and the photographed fundus image is automatically obtained. Since the masking process is performed, small pupil photography can be suitably performed with a simple configuration.

  An example of an embodiment of a fundus camera according to the present invention will be described in detail with reference to the drawings. Hereinafter, in order to limit the field of view of the fundus image, a field stop that blocks a part of the reflected light from the fundus of the illumination light, and the reflected light that is partially blocked by the field stop are captured by the imaging means (CCD). A fundus camera having a relay lens that relays and forms an image on an imaging surface will be described as a first embodiment, and a shielding diaphragm that shields reflected light from the cornea of illumination light in the vicinity of the imaging surface of the imaging means A fundus camera having a configuration including the above will be described as a second embodiment. The fundus camera according to the present invention is not limited to the configurations shown in the first and second embodiments.

[First Embodiment]
[Configuration of optical system]
FIG. 1 is a schematic configuration diagram showing an example of an optical system of a fundus camera according to the present invention. The fundus camera of this embodiment receives an illumination system 10 for irradiating the fundus Ef of the eye E to be examined with illumination light for observation and photographing, and light reflected by the fundus Ef irradiated with the illumination light. A shooting system 20 having a TV camera 20A and a TV camera 20B for shooting is provided. An image photographed by the TV camera 20B is displayed on the monitor M. The TV camera 20A and the TV camera 20B are each provided with a CCD as an image sensor. The imaging system 20 also serves as an optical system for observing the fundus oculi Ef.

(Lighting system)
The illumination system 10 includes a halogen lamp 11, a condenser lens 12, a xenon lamp 13, a condenser lens 14, a ring slit 15, light shielding points 16a and 16b, a reflection mirror 17, and a relay lens 18. Has been. Although illustration is omitted, an exciter filter disposed on the optical axis when performing fluorescence imaging using the xenon lamp 13, and a liquid crystal display for displaying a fixation target and projecting it on the eye E to be examined Etc. are also included.

  The halogen lamp 11 is a light source that is turned on when the examiner observes the fundus oculi Ef or when taking a moving image. The condenser lens 12 is a lens for collecting illumination light emitted from the halogen lamp 11 and irradiating the fundus oculi Ef evenly. The xenon lamp 13 is a light source that is turned on when taking a still image of the fundus oculi Ef. The condenser lens 104 is a lens for collecting the illumination light emitted from the xenon lamp 103 and irradiating the fundus oculi Ef evenly.

  The ring slit 15 is disposed at a position conjugate with the anterior eye portion of the eye E to be examined, and includes a ring-shaped translucent region 15a with the optical axis as the center. The illumination light passes through the light transmitting region 15a of the ring slit 15 and is irradiated onto the eye E as a light beam having a ring shape in cross section.

  The light shielding points 16 a and 16 b (sometimes collectively referred to as the light shielding points 16) are movable in the direction of the arrow shown in FIG. 1, that is, the direction orthogonal to the optical axis of the illumination system 10. The light shielding points 16 are moved by driving means such as a solenoid (not shown) so as to be selectively disposed on the optical axis of the illumination system 10. Here, the light shielding point 16a is formed to have a smaller diameter than the light shielding point 16b. Therefore, when the light shielding point 16a is arranged on the optical axis, a small area near the center of the cross section of the (ring-shaped) illumination light is shielded, and when the light shielding point 16b is arranged on the optical axis, the illumination light A relatively large area near the center of the cross section is shielded from light. The light shielding point according to the present invention is not limited to such a configuration. For example, three or more light-shielding points having different diameters may be configured to be selectively arranged on the optical axis. Alternatively, a light shielding point that can move in the optical axis direction of the illumination system 10 is provided, and the region where the illumination light is shielded may be changed by changing the position thereof. In any case, the light shielding point 16 may be configured so that the region for shielding the illumination light can be changed.

  The reflection mirror 17 is a mirror for reflecting the illumination light from the halogen lamp 11 and the xenon lamp 13 and guiding it in the optical axis direction of the photographing system 20. The relay lens 18 is a lens for relaying the illumination light reflected by the reflection mirror 17 in the optical axis direction of the photographing system 20.

(Shooting system)
The photographing system 20 of the fundus camera of this embodiment includes an objective lens 21, a perforated mirror 22, a photographing aperture 23, a focusing lens 24, a quick return mirror 25, a field lens 26, a field stop 27, and a prism. 28, a relay lens 29, a variable power lens 29A, and a TV camera 20A. The TV camera 20A constitutes an imaging unit according to the present invention, and includes a CCD as an imaging device at a position conjugate with the fundus oculi Ef of the eye E to be examined. Although illustration is omitted, a barrier filter or the like that is disposed on the optical axis of the imaging system 20 at the time of fluorescence imaging described above is further provided.

  Here, the objective lens 21, the aperture mirror 22, the imaging aperture 23, the focusing lens 24, the field lens 26, and the field aperture 27 constitute the first imaging system according to the present invention, and the reflected light from the fundus oculi Ef is Then, an image is formed once at the position of the field stop 27 via the objective lens 21 to the field lens 26.

  The relay lens 29, the variable power lens 29A, and the TV camera 20A constitute a second photographing system according to the present invention, and the reflected light once imaged at the position of the field stop 27 is imaged by the CCD of the TV camera 20A. Re-image the surface.

  The objective lens 21 is a lens that faces the eye E when observing or photographing the fundus oculi Ef. The aperture mirror 22 acts to synthesize the optical axis of the illumination system 10 and the optical axis of the imaging system 20, and the reflected light from the fundus oculi Ef of the illumination light through the hole 22a formed near the center thereof. Is directed toward the TV cameras 20A and 20B. The photographing diaphragm 23 is disposed at a position conjugate with the pupil of the eye E to be examined. The focusing lens 24 is provided so as to be movable along the optical axis of the imaging system 20 by driving means such as a solenoid (not shown). In the present embodiment, the single focusing lens 24 is used for focusing. However, a focusing lens system including a plurality of lenses may be used.

  The quick return mirror 25 is provided so as to be rotatable about a rotation shaft 25a. When performing fundus photographing with the TV camera 20A, the quick return mirror 25 is flipped up in the drawing and retracted from the optical axis of the photographing system 20. The reflected light from the fundus oculi Ef is guided to the TV camera 20A. On the other hand, when shooting with the TV camera 20B, the quick return mirror 25 is disposed on the optical axis of the shooting system 20, and is controlled to guide the reflected light to the TV camera 20B.

  The field stop 27 is for restricting the field of view of the fundus image in order to shield the reflected light of the illumination light from the cornea of the eye E, near the rear of the field lens 26 (on the TV camera 20A side), and It is arranged at a position conjugate with the fundus oculi Ef. Depending on the configuration of the optical system, the field stop 27 may be arranged near the front of the field lens 26 (on the objective lens 21 side).

  The prism 28 is for reflecting the reflected light from the fundus oculi Ef guided by the first imaging system and changing its traveling direction.

  The relay lens 29 is a lens for relaying the reflected light from the fundus oculi Ef once imaged by the first imaging system and reflected by the prism 28 to re-image on the CCD imaging surface of the TV camera 20A. . The variable power lens 29A is detachably provided on the optical axis of the photographing system 20 by driving means such as a solenoid (not shown). The variable power lens 29A constitutes a variable power unit referred to in the present invention together with a variable power processing unit of a control system described later.

  The imaging system 20 further includes a diaphragm 31, a field lens 32, a reflection mirror 33, and a relay lens 34 as optical elements that guide reflected light from the fundus oculi Ef to the TV camera 20B.

  With the optical system having such a configuration, the fundus oculi Ef of the eye E is observed and photographed as follows. First, when the fundus oculi Ef is observed on the monitor M, the quick return mirror 25 is disposed obliquely on the optical axis of the imaging system 20, and the halogen lamp 11 is turned on. Illumination light emitted from the halogen lamp 11 irradiates the ring slit 15 via the condenser lenses 12 and 14. The illumination light that has passed through the light-transmitting region 15a of the ring slit 15 becomes a ring-shaped light beam in its cross section. When the light shielding point 16 (16a or 16b) is arranged on the optical axis, the central region of the illumination light is shielded by the light shielding point 16. The illumination light is reflected by the reflection mirror 17, relayed by the relay lens 18, reflected by the aperture mirror 22 along the optical axis of the imaging system 20 in the direction of the eye E, and converged by the objective lens 21. It enters the eye E and illuminates the fundus oculi Ef. At this time, since the ring slit 15 is disposed at a position conjugate with the anterior eye portion of the eye E, an image having a shape (that is, a ring shape) of the light transmitting region 15a of the ring slit 15 is formed on the anterior eye portion. .

  The illumination light that irradiates the fundus oculi Ef of the eye E is reflected by the fundus oculi Ef. The fundus reflection light passes through the dark part of the central region of the ring-shaped image formed on the anterior eye part, is emitted from the eye E, is converged by the objective lens 21, and is taken by the hole part 22a of the perforated mirror 22. The light is reflected upward by the quick return mirror 25 through the aperture 23 and the focusing lens 24. The fundus reflection light reflected upward is reflected by the reflection mirror 32 through the diaphragm 31 and the field lens 32, and is imaged and photographed on the CCD imaging surface of the TV camera 20B by the relay lens 34. On the monitor M, a fundus oculi image Ef ′ photographed by the TV camera 20B is displayed.

  On the other hand, when photographing the fundus oculi Ef with the TV camera 20A, the quick return mirror 25 is retracted from the optical axis of the photographing system 20, and the xenon lamp 13 is flashed. This illumination light irradiates the ring slit 15 via the condenser lens 14. The illumination light that has passed through the light-transmitting region 15a of the ring slit 15 becomes a ring-shaped light beam in its cross section. When the light shielding point 16 (16a or 16b) is arranged on the optical axis, the central region of the illumination light is shielded by the light shielding point 16. The illumination light is reflected by the reflection mirror 17, relayed by the relay lens 18, reflected by the aperture mirror 22 along the optical axis of the imaging system 20 in the direction of the eye E, and converged by the objective lens 21. It enters the eye E and illuminates the fundus oculi Ef. At this time, the illumination light forms a ring-shaped image on the anterior segment.

  The illumination light that irradiates the fundus oculi Ef is reflected, passes through the dark part of the central region of the ring-shaped image, and is emitted from the eye E to be examined. The fundus reflection light is converged by the objective lens 21 and imaged at the position of the field stop 27 through the hole 22a of the aperture mirror 22, the photographing aperture 23, the focusing lens 24 and the field lens 26. The fundus reflection light once imaged at the position of the field stop 27 is reflected by the prism 28 to change its traveling direction, and is re-imaged on the CCD imaging surface of the TV camera 20A by the relay lens 29. Thereby, a fundus image of the eye E is taken. Note that when taking a fundus image at a high magnification, the variable power lens 29A is inserted on the optical path of the fundus reflected light.

[Control system configuration]
Next, the configuration of the control system of the fundus camera of the present embodiment will be described with reference to the block diagram shown in FIG. The control system of the fundus camera is configured around a control unit 40 that performs overall control of the apparatus and control of each unit. The control unit 40 includes an image storage unit 41, a display unit 42, an input operation unit 43, a small pupil mode setting unit 44, a driving unit 45 for moving the light shielding point 16 (16a, 16b), and a variable power lens 29A. A driving means 46 for inserting / removing the optical axis of the imaging system 20, a masking processing unit 47, and a scaling processing unit 48 are respectively connected. Further, the TV camera 20A is connected to the control unit 40, and the control unit 40 performs control for displaying a captured image. Although not shown, a power supply circuit for causing the halogen lamp 11 and the xenon lamp 13 to emit light, driving means for operating the quick return mirror 25, and the like are connected to the control unit 40.

  The control unit 40 constitutes a “control unit” according to the present invention, and an arithmetic control device such as a CPU that executes various arithmetic operations and controls, and causes the arithmetic control device to execute predetermined arithmetic processing and control processing. And a storage device such as a ROM for storing various programs and various data. In particular, the storage device stores a program for performing various electrical processes (digital image processing) on an image photographed by the TV camera 20A.

  The image storage unit 41 includes a storage device (or a predetermined storage area of the storage device) for storing images taken by the TV camera 20A. The control unit 40 receives an image captured by the TV camera 20 </ b> A and causes the image storage unit 41 to store the captured image.

  The display unit 42 is a display device such as a monitor for displaying an image photographed by the TV camera 20A. The control unit 40 converts an image captured by the TV camera 20A into image data such as an RGB signal, performs predetermined digital image processing on the image data as necessary, and sends the image data to the display unit 42. Send and display. In addition, the display unit 42 may be configured to also serve as a monitor M (see FIG. 1) that displays an image captured by the TV camera 20B.

  The input operation unit 43 is a user interface that receives an input operation performed by the user to operate each unit of the fundus camera of the present embodiment. For example, a power switch for switching on / off the power of the apparatus, a switch for switching between color photographing / fluorescent photographing, and a switch for switching between the TV camera 20A / TV camera 20B as an imaging means, etc. is there. Further, a switch for manually setting execution of a masking process and a scaling process described later may be included. Furthermore, an operation switch for manually changing the light shielding point 16 arranged on the optical axis of the illumination system 10 may be provided. The control unit 40 controls the setting and operation of each unit of the fundus camera according to the input content from the input operation unit 43.

  The small pupil mode setting unit 44 is an operation means including a switch, a button, a touch panel, or the like operated when setting a small pupil photographing mode for photographing a fundus image of the eye E to be examined having a small pupil diameter. When the user operates the small pupil mode setting unit 44 to set the small pupil photographing mode, the control unit 40 controls the driving unit 46 to insert the variable power lens 29A on the optical axis of the photographing system 20 to set the photographing magnification. High magnification. Note that when the shooting magnification increases, the shooting angle of view decreases. Here, the small pupil mode setting unit 44 may be configured as a part of the input operation unit 43. The small pupil mode setting unit 44 constitutes “small pupil mode setting means” according to the present invention.

  The driving unit 45 switches and arranges the light shielding point 16 on the optical axis of the illumination system 10 under the control of the control unit 40. That is, the control means 40 controls the drive means 45 to switch between arranging the light shielding point 16a, arranging the light shielding point 16b, or not arranging them. As a specific configuration of the driving unit 45, a solenoid, a pulse motor, or the like can be used as appropriate.

  The driving unit 46 drives the variable power lens 29A to be inserted into and removed from the optical axis of the photographing system 20 in order to change the photographing magnification of the fundus image by the TV camera 20A according to the control of the control unit 40. As the driving means 46, a solenoid, a pulse motor, or the like can be used as appropriate as in the driving means 45.

  The masking processing unit 47 performs an electrical masking process on an image photographed by the TV camera 20A. The masked image is stored in the image storage unit 41 and displayed on the display unit 42. Here, the electrical masking is to mask unnecessary partial areas such as a flare occurrence area of the photographed image by electrical processing, that is, digital processing. In this embodiment, in particular, in the crystalline lens of the eye E to be examined. The purpose of this is to remove flare caused by the scattered light and the reflected light at the boundary surface between the crystalline lens and the vitreous body. The masking processing unit 47 constitutes “masking means” referred to in the present invention.

  By the way, in the normal fundus camera, the eye E is irradiated with illumination light having a ring-shaped cross section, and the fundus reflection light is emitted from the eye E through the central region in the ring of illumination light, and the above-described field stop Since the peripheral region of the fundus reflection light is shielded by 27, adverse effects such as flare caused by the corneal reflection light of the illumination light mixed in the fundus reflection light are suppressed. However, the flare generated by the reflected light of the illumination light in the crystalline lens of the eye E cannot be removed. The masking processing unit 47 included in the fundus camera of the present embodiment executes digital processing for removing flare caused by the crystalline lens based on the control of the control unit 40.

  The masking processing unit 47 removes the influence of the flare by synthesizing a predetermined mask image (for example, a black ring-shaped image) with the flare occurrence area of the captured image. Further, the influence of flare is removed by replacing image data corresponding to the flare occurrence area with, for example, black display data. It is also possible to form a different mask image and perform masking processing each time by detecting the flare occurrence area by analyzing the brightness of each area of the captured image, the sharpness of the boundary line, and the like. . In this case, a mask image corresponding to each patient may be stored and stored in a database, and a mask image for the patient may be selected from the database and used for the subsequent fundus photographing.

  Further, when a fundus image captured by the TV camera 20A is printed out by a printer or the like (not shown), identification information (for example, a cutout portion of a mask or an arrow mark) is attached to identify the vertical direction of the printed image. It may be.

  Under the control of the control unit 40, the scaling processing unit 48 performs a process of zooming up / down the image captured by the TV camera 20A electrically, that is, digitally. The processed image is stored in the image storage unit 41 and displayed on the display unit 42. The magnification processing unit 48, together with the magnification lens 29A of the photographing system 20, constitutes a “magnification unit” referred to in the present invention. In general, the zoom unit according to the present invention does not need to include both the zoom lens and the zoom processing unit 48, and may include only one of them according to the configuration of the apparatus.

  In the present embodiment, the fundus camera body is described as having a control system, but the present invention is not limited to such a configuration. For example, when adopting a configuration in which an information processing apparatus such as a computer terminal is connected to the fundus camera body by wired or wireless data communication means and the fundus camera is controlled by the information processing apparatus, the control unit 40 and the image storage unit 41 are employed. In addition, at least one of the display unit 42, the input operation unit 43, the small pupil mode setting unit 44, the masking processing unit 47, and the scaling processing unit 48 may be provided in the information processing apparatus. In particular, the image storage unit 41 is configured to separately provide a storage device such as a hard disk drive having a large storage capacity outside the main body in order to store a large number of images, and to form a database of photographed fundus images for each patient. It is preferable. In addition, a plurality of fundus cameras may be connected via a network such as a LAN, and images captured by each fundus camera may be collectively managed by a server (and database).

[Processing procedure]
A processing procedure of fundus photographing by the fundus camera of the present embodiment including the optical system and the control system configured as described above will be described. Each processing procedure shown below is a processing mode when a fundus image of the eye E is captured by the TV camera 20A. Therefore, it is assumed that preliminary processing (processing related to the illumination light source, the quick return mirror 25, and the like) for photographing with the TV camera 20A is complete. Each processing procedure is controlled and executed by the control unit 40 that operates based on a predetermined program. It should be noted that the fundus camera according to the present invention need not be configured to be able to execute all the following processing procedures, and only needs to be able to execute at least one of them. Further, each processing procedure may be configured to be usable according to the user's selection.

(First processing form)
A basic processing form of the fundus camera of the present embodiment will be described with reference to a flowchart shown in FIG. First, the fundus image of the eye E is photographed by the TV camera 20A (S1). Image data of the photographed fundus image is transmitted to the control unit 40 and stored in the image storage unit 41. Next, at the time of photographing the fundus image, the control unit 40 detects whether or not the light shielding point 16 of the illumination system 10 has a small diameter, that is, the light shielding point 16b (S2). Since the change process of the light shielding point 16 is executed by the control unit 40, the control unit 40 performs the determination process based on the information of the change process.

  When it is detected that the photographing process of S1 is performed in a state where the small-diameter shading point 16b is arranged on the optical axis of the illumination system 10 (S2; YES), the control unit 40 stores the fundus stored in the image storage unit 41. The image data is sent to the masking processing unit 47, and the masking processing unit 47 is controlled to execute masking processing for the fundus image (S3). When the masking process is performed, the control unit 40 stores the image in the image storage unit 41 and transmits the image to the display unit 42 for display (S4).

  On the other hand, when it is detected in step S2 that the light shielding point 16a is used, or when it is detected that any light shielding point 16 is not used (S2; NO), the control means 40 adds the captured image to the TV camera 20A. Without performing the masking process, the captured image is transmitted to the display unit 42 and displayed (S4).

  According to such a processing procedure, electrical masking is automatically performed on the fundus image captured using the light-shielding point 16b having a small diameter, so that flare caused by the crystalline lens of the eye E can be easily performed. And can be effectively removed. Further, since the reflected light of the illumination light from the cornea of the eye E is shielded by the field stop 27, a good fundus image without smearing or blooming can be easily taken. Moreover, the structure for that is not complicated as mentioned above but simple.

  In this processing mode, the masking process is performed in response to the selection of the light blocking point 16b having a small diameter, but more generally, the area of the illumination light blocked by the light blocking point is continuous or Corresponding to the change so as to be discretely reduced, it is possible to control to perform a masking process on the captured image. In particular, a predetermined threshold value is set in the light shielding area of the illumination light formed by the light shielding point, and the masking processing unit corresponds to the light shielding point being changed so that the light shielding area becomes smaller than the threshold value. 47 can be controlled to operate.

  Further, in the processing shown in S3 of the flowchart of FIG. 3, the copy data of the fundus image data stored in the image storage unit 41 is sent to the masking processing unit 47, and the copy data is subjected to masking processing. In the processing shown, the copy data subjected to the masking processing may be stored in the image storage unit 41 together with the original data.

(Second processing mode)
Next, another processing mode of the fundus camera of the present embodiment will be described with reference to the flowchart of FIG. This processing form is executed when the user performs an operation for electrically scaling the captured image to the high magnification from the input operation unit 43. Note that processing in the case where the zoom lens 29A is arranged on the optical axis of the shooting system 20 to optically zoom the shot image will be described later.

  When an operation is performed to enlarge the fundus image from the input operation unit 43 (S11; YES), the control unit 40 controls the driving unit 45 so that the light-shielding point 16b having a small diameter is placed on the optical axis of the illumination system 10. Arrange (S12). In this state, the fundus image of the eye E is taken by the TV camera 20A (S13). Further, the control unit 40 controls the magnification processing unit 48 to send the photographed fundus image to the magnification processing unit 48 and digitally scale the image to a high magnification to form an enlarged image of the fundus image (S14). .

  The control unit 40 sends the image data of the photographed fundus image to the masking processing unit 47 and controls the masking processing unit 47 to execute a masking process for the fundus image (S15). When the masking process is performed, the control unit 40 stores the image in the image storage unit 41 and displays the image on the display unit 42 (S16).

  On the other hand, when the photograph is taken at a normal magnification (S11; NO), a fundus image is taken by the TV camera 20A (S17), and the photographed fundus image is displayed without masking the taken image. The data is displayed on the unit 42 (S16).

  According to such a processing procedure, the fundus image photographed at a high magnification is automatically masked, so that flare caused by the crystalline lens of the eye E can be easily and effectively removed. can do. Moreover, the structure for that is also simple.

  Furthermore, since the reflected light of the illumination light from the cornea of the eye E is shielded by the field stop 27, the influence of smear and blooming caused by the cornea reflected light is effectively removed.

  In this processing mode, masking processing is performed in response to the shooting magnification being set to a high magnification. In particular, a predetermined threshold value is set for the shooting magnification and is higher than the threshold value. The masking processing unit 47 can be controlled to operate in response to the change to the magnification.

(Third processing mode)
Still another processing form of the fundus camera of the present embodiment will be described with reference to the flowchart of FIG. This processing form is executed when the user sets fundus photographing in the small pupil photographing mode from the small pupil mode setting unit 44.

  When the small pupil photographing mode is set by operating the small pupil mode setting unit 44 (S21; YES), the control unit 40 controls the driving unit 45 to block the light-shielding point having a small diameter on the optical axis of the illumination system 10. 16b is arranged (S22). At this time, each part of the apparatus is controlled to a setting state corresponding to the small pupil photographing mode such that the variable power lens 29A and the focusing lens 24 are arranged at predetermined positions. In this state, the fundus image of the eye E is taken by the TV camera 20A (S23).

  The control unit 40 sends the image data of the photographed fundus image to the masking processing unit 47 and controls the masking processing unit 47 to execute a masking process for the fundus image (S24). When the masking process is performed, the control unit 40 stores the image in the image storage unit 41 and displays the image on the display unit 42 (S25).

  On the other hand, in the case of normal imaging instead of the small pupil imaging mode (S21; NO), a fundus image is captured by the TV camera 20A (S26), and the captured fundus is not subjected to masking processing. The image is displayed on the display unit 42 (S25).

  According to such a processing procedure, since the fundus image captured in the small pupil photographing mode is automatically masked, flare caused by the crystalline lens of the eye E is easily and effectively removed. can do. Further, since the reflected light of the illumination light from the cornea of the eye E is shielded by the field stop 27, a good fundus image without smearing or blooming can be easily taken. Moreover, the structure for that is also simple.

  By the way, in the case of photographing in the small pupil photographing mode, when the magnification is optically changed by the magnification changing lens 29A, the magnification changing lens 29A is disposed between the field stop 27 and the TV camera 20A. The image of the aperture 27 is not recorded by the TV camera 20A. Therefore, the reflected light of the illumination light from the cornea cannot be blocked, and smearing or blooming occurs in the captured image. Even in this case, according to the fundus camera of the present embodiment, the captured image is subjected to masking processing, and the influence of the corneal reflection light is effectively removed, so that a good fundus image without smear or blooming can be easily obtained. You can shoot. Even when the input operation unit 33 is manually operated to set the optical magnification to high magnification, the same operation can be realized by executing the processing shown in the third processing mode.

[Second Embodiment]
[Configuration of optical system]
FIG. 6 is a schematic configuration diagram showing an example of an optical system of another fundus camera according to the present invention. In the figure, the same components as those in the first embodiment may be described with the same reference numerals. Since the fundus camera of the present embodiment includes the illumination system 10 similar to that of the first embodiment, refer to the description of the first embodiment for details thereof. Further, the photographing system 20 of this embodiment has an optical configuration different from that of the first embodiment. In particular, the imaging system 20 of the present embodiment includes various filters and cover glasses immediately before the TV camera, and considers that it is difficult to place a field stop at a position conjugate with the fundus oculi Ef of the eye E to be examined. Thus, a configuration is adopted in which the corneal reflection light of the illumination light is cut by providing a light-shielding stop as close as possible to the imaging surface of the CCD.

(Shooting system)
The photographing system 20 of the fundus camera according to the present embodiment includes an objective lens 21, a perforated mirror 22 having a hole 22a, a photographing aperture 23, a focusing lens 24 ', a photographing lens 25', and a variable magnification lens 26 '. And a quick return mirror 27 ′, a shielding stop 28 ′, a filter 29 ′, and a camera (imaging means) provided with a CCD 20 C as an imaging device. The imaging surface of the CCD 20C is arranged at a position conjugate with the fundus oculi Ef of the eye E to be examined.

  The shielding stop 28 'is an optical member for shielding the reflected light of the illumination light from the cornea of the eye E. The filter 29 ′ is, for example, an infrared cut filter that suppresses ghost and fog by cutting off an infrared component included in reflected light of illumination light from the fundus oculi Ef of the eye E to be examined, or an unnecessary component of fundus reflected light. And a low-pass filter that prevents false color and color moire.

  The objective lens 21, the perforated mirror 22, the photographing aperture 23, the focusing lens 24 ', and the photographing lens 25' constitute a first photographing system according to the present invention. Further, the shielding diaphragm 28 ', the filter 29', and the CCD 20C constitute a second photographing system.

  Further, the photographing system 20 is provided with a TV camera 20B for photographing an image displayed on the monitor M, a quick return mirror 31 ', a field lens 32', a reflecting mirror 33, a relay lens 34, a field lens 35, and an eyepiece lens 36. It has been.

  The quick return mirror 31 ′ is provided so as to be rotatable about a rotation shaft 31 a ′, and acts to switch the optical path of fundus reflected light reflected by the quick return mirror 27 ′. Specifically, when photographing the fundus oculi Ef of the eye E with the TV camera 20B, the quick return mirror 31 ′ is retracted from the optical path of the fundus reflected light, and the field lens 32 ′, the reflection mirror 33, and the relay lens 34 are passed through. Then, the fundus reflection light is guided to the TV camera 20B. An image captured by the TV camera 20B is displayed on the monitor M as a fundus oculi image Ef ′. On the other hand, when the examiner observes the fundus oculi Ef, the quick return mirror 31 ′ is obliquely arranged on the optical path to reflect the fundus reflected light and is guided to the examiner's eyes via the field lens 35 and the eyepiece 36. It is like that.

  The fundus camera of this embodiment includes a control system similar to that shown in FIG. 2 and is configured to be able to execute processing procedures similar to those shown in the flowcharts shown in FIGS. As a result, the reflected light from the cornea is shielded by the shielding stop 28 ', and the influence of smear and blooming is removed, and the flare caused by the crystalline lens of the eye E is removed by an electrical masking process. Therefore, it is possible to easily shoot a good fundus image free from the effects of smear, blooming and flare. Moreover, the structure for that is also simple.

  In addition, although the fundus camera of each embodiment described above is provided with the optical configuration as described above, the fundus camera according to the present invention is not limited to this. The fundus camera according to the present invention includes an illumination system that can change the size of the light-shielding point, includes at least an objective lens and a photographing aperture as a first photographing system, and receives at least fundus reflected light by a CCD and receives an eye to be examined. An imaging means for capturing the fundus image of the image as a second imaging system, and a partial area of the fundus reflected light received by the imaging means, that is, a partial area of the photographed fundus image, according to the size of the light shielding point. It is sufficient to provide a masking means controlled so as to be electrically masked.

  The first embodiment specifically discloses an example of a configuration in which a field stop is included in the first imaging system of such a fundus camera and a relay lens is included in the second imaging system. is there. The second embodiment discloses an example of a configuration in which the second photographing system of the fundus camera according to the present invention further includes a shielding stop.

  The configuration described in detail above is merely a specific example for carrying out the present invention, and various modifications can be made within the scope of the gist of the present invention.

It is the schematic which shows an example of the structure of the optical system with which the fundus camera which concerns on the 1st Embodiment of this invention is provided. It is a block diagram which shows an example of the structure of the control system with which the retinal camera which concerns on the 1st Embodiment of this invention is provided. It is a flowchart which shows an example of the process sequence by the fundus camera which concerns on the 1st Embodiment of this invention. It is a flowchart which shows an example of the process sequence by the fundus camera which concerns on the 1st Embodiment of this invention. It is a flowchart which shows an example of the process sequence by the fundus camera which concerns on the 1st Embodiment of this invention. It is the schematic which shows an example of the structure of the optical system with which the retinal camera which concerns on the 2nd Embodiment of this invention is provided.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Illumination system 15 Ring slit 16 (16a, 16b) Shading point 20 Shooting system 20A TV camera (imaging means)
20C CCD
DESCRIPTION OF SYMBOLS 21 Objective lens 23 Imaging stop 27 Field stop 29 Relay lens 29A Variable lens 26 'Variable lens 28' Shielding diaphragm 40 Control part (control means)
44 Small pupil mode setting section (small pupil mode setting means)
47 Masking section (masking means)
48 Scaling processing unit (scaling means)
E Eye to be examined Ef Fundus

Claims (6)

A ring slit that is arranged at a position conjugate with the anterior eye portion of the eye to be examined and that illuminates the fundus of the eye to be examined has a ring-shaped cross section, and is arranged at a position different from the ring slit to shield the illumination light. An illumination system including a member that constitutes a light-shielding point capable of changing the area;
An objective lens arranged facing the eye to be examined; and an imaging diaphragm arranged at a position conjugate with the pupil of the eye to be examined; reflection of the illumination light by the fundus through the objective lens and the imaging diaphragm A first imaging system for imaging light;
A second imaging system that is disposed at a position conjugate to the fundus and includes an imaging unit that receives the reflected light by a CCD and images a fundus image of the eye to be examined;
A masking means controlled to electrically mask a partial area of the reflected light received by the imaging means in response to a change in the area of the illumination light shielded by the light shielding point;
A fundus camera comprising: The first imaging system further includes a field stop that is disposed at a position conjugate with the fundus and shields a partial region of the reflected light in order to limit the imaging field of the fundus image,
2. The second imaging system further includes a relay lens that relays the reflected light, the partial area of which is shielded by the field stop, to form an image on an imaging surface of the imaging means. The described fundus camera.   2. The second imaging system further includes a shielding diaphragm disposed in the vicinity of an imaging surface of the imaging means for shielding the reflected light of the illumination light by the cornea of the eye to be examined. The described fundus camera.   The masking means electrically masks a partial area of the reflected light received by the imaging means in response to the change of the area of the illumination light shielded by the light shielding point to be small. The fundus camera according to any one of claims 1 to 3, wherein the fundus camera is controlled as described above. A scaling unit for changing a photographing magnification of the fundus image captured by the imaging unit;
Control for controlling the member constituting the light shielding point so as to reduce the area of the illumination light shielded by the light shielding point in response to the photographing magnification by the magnification changing means being changed to a predetermined magnification or more. Means,
The fundus camera according to claim 4, further comprising: A small pupil mode setting means for setting a small pupil photographing mode in which a photographing field angle is set to be small in order to photograph a fundus image of a subject's eye having a small pupil diameter;
Control means for controlling the member constituting the light shielding point so as to reduce the area of the illumination light shielded by the light shielding point in response to the setting of the small pupil photographing mode by the small pupil mode setting means. When,
The fundus camera according to claim 4, further comprising:

Images