JP5864123B2 - Fundus photographing device - Google Patents

Description

  The present invention relates to a fundus imaging apparatus that images the fundus of a subject's eye.

  Techniques for photographing the fundus to grasp the state of the eye to be examined are known (see, for example, Patent Documents 1 and 2). When taking a still image of the fundus, a strobe light source such as a xenon lamp and an image sensor such as a CCD are controlled synchronously.

  There are the following methods for this synchronous control. The first method is to input trigger signals to the strobe light source and the image sensor, respectively. The second method is to synchronize these using an image board or a relay board. In the third method, the strobe light source is caused to emit light after a predetermined time has elapsed since the trigger signal was input to the image sensor.

JP 2009-172156 A JP 2002-28136 A

  Some image sensors cannot input trigger signals. For example, analog video cameras (NTSC, PAL, etc.) repeatedly receive light and output image signals at predetermined time intervals. In this case, the second method described above is used.

  However, in the second method, it is necessary to change the hardware configuration such as adding a dedicated relay board, which causes problems such as an increase in cost and a complicated configuration.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a fundus imaging apparatus capable of performing imaging by synchronizing a light source and an image sensor without changing a hardware configuration. Is to provide.

In order to achieve the above object, an invention according to claim 1 includes a light source that outputs flash light, an illumination optical system that irradiates the fundus of the eye to be examined, and fundus reflection light of the flash light. A first image sensor that detects and generates an image signal; an optical filter that can be inserted into and removed from an optical path between the light source and the first image sensor; and an insertion timing of the optical filter into the optical path. Control means for controlling the output timing of the flash light by the light source , the illumination optical system includes a steady light source that outputs steady light, irradiates the fundus with the steady light, A second image sensor that receives fundus reflected light at predetermined time intervals and generates an image signal; and the control unit generates an image signal generated by the second image sensor. A fundus photographing apparatus characterized by analyzing the moving image based on including an analysis means for identifying said insertion timing.
The invention according to claim 2 is the fundus photographing apparatus according to claim 1, wherein the optical filter is a bandpass filter, and the analysis means monitors the brightness of the moving image, and The timing when the brightness decreases is specified as the insertion timing .
The invention according to claim 3 includes a light source that outputs flash light, an illumination optical system that irradiates the fundus of the subject's eye with the flash light, and an image signal obtained by detecting fundus reflection light of the flash light. The first image sensor to be generated, an optical filter that can be inserted into and removed from the optical path between the light source and the first image sensor, and the optical source based on the insertion timing of the optical filter with respect to the optical path. Control means for controlling the output timing of flash light, and the control means causes the light source to start outputting the flash light based on the insertion timing, and further, after starting the output of the flash light, The fundus photographing apparatus is characterized in that the flash light is output a plurality of times before the optical filter is retracted from the optical path.
The invention described in claim 4 includes a light source that outputs flash light, an illumination optical system that irradiates the fundus of the subject's eye with the flash light, and an image signal obtained by detecting fundus reflected light of the flash light. The first image sensor to be generated, an optical filter that can be inserted into and removed from the optical path between the light source and the first image sensor, and the optical source based on the insertion timing of the optical filter with respect to the optical path. Control means for controlling the output timing of the flash light, wherein the control means causes the light source to start outputting the flash light based on the insertion timing, and further determines in advance from the start of the output of the flash light. The fundus photographing apparatus is characterized in that the output of the flash light is repeated for a predetermined time.
The invention described in claim 5 includes a light source that outputs flash light, an illumination optical system that irradiates the fundus of the subject's eye with the flash light, and an image signal obtained by detecting fundus reflected light of the flash light. The first image sensor to be generated, an optical filter that can be inserted into and removed from the optical path between the light source and the first image sensor, and the optical source based on the insertion timing of the optical filter with respect to the optical path. Control means for controlling the output timing of the flash light, the control means causing the light source to start outputting the flash light based on the insertion timing, causing the flash light to be output a plurality of times, and the plurality of times. Analyzing a plurality of images based on a plurality of image signals from the first image sensor detecting the fundus reflection light of the output flash light, A fundus photographing apparatus characterized by comprising selecting means for selecting an image.
The invention according to claim 6 is the fundus imaging apparatus according to claim 5 , wherein the selection means obtains the brightness of each of the plurality of images and selects the image having the maximum brightness. It is characterized by that.

  According to the present invention, since the output timing of the flash light from the light source is controlled based on the insertion timing of the optical filter with respect to the optical path, the operation of the light source and the image sensor can be performed without any additional hardware. The operation can be synchronized. That is, according to the present invention, it is possible to perform photographing while synchronizing the light source and the image sensor without changing the hardware configuration.

It is the schematic showing an example of the structure of the optical system in embodiment of the fundus imaging apparatus concerning this invention. It is the schematic showing an example of the structure of the control system in embodiment of the fundus imaging apparatus concerning this invention. It is the schematic showing the synchronous relationship of the NTSC signal and FI signal in embodiment of the fundus imaging apparatus concerning this invention. It is a timing chart showing an example of operation in an embodiment of a fundus photographing apparatus concerning this invention.

  An example of an embodiment of a fundus imaging apparatus according to the present invention will be described. In this embodiment, a fundus camera will be described. However, for example, a slit lamp (slit lamp microscope apparatus) or an ophthalmic surgical microscope may be used.

[Constitution]
The entire configuration of the fundus imaging apparatus according to this embodiment is shown in FIGS. FIG. 1 shows a configuration example of an optical system of the fundus imaging apparatus 1. FIG. 2 shows a configuration example of a control system of the fundus imaging apparatus.

  The fundus photographing apparatus 1 is provided with an optical system for forming a two-dimensional image (fundus image) representing the surface form of the fundus oculi Ef of the eye E to be examined. The fundus image includes an observation image and a captured image. The observation image is, for example, a moving image of the fundus oculi Ef photographed using near infrared light. The captured image is, for example, a still image of the fundus oculi Ef obtained by flashing visible light. Examples of the still image include a color image, a fluorescein fluorescent image, an indocyanine green fluorescent image, and a spontaneous fluorescent image. The fundus imaging apparatus 1 can also image the anterior segment of the eye E.

  The fundus photographing apparatus 1 is provided with a chin rest and a forehead for supporting the subject's face so that the face of the subject does not move, as in a conventional fundus camera. Furthermore, the fundus photographing apparatus 1 is provided with an illumination optical system 10 and a photographing optical system 30 as in the conventional fundus camera. The illumination optical system 10 irradiates the fundus oculi Ef with illumination light. The photographing optical system 30 guides the fundus reflection light of the illumination light to the imaging device (image sensors 37 and 43).

(Optical system)
The observation light source 11 of the illumination optical system 10 is a stationary light source that outputs stationary light. The observation light source 11 is composed of, for example, a halogen lamp or LED (Light Emitting Diode). The light (observation illumination light) output from the observation light source 11 is reflected by the reflection mirror 12 having a curved reflection surface, passes through the condensing lens 13, passes through the visible cut filter 14, and is converted into near infrared light. Become. Further, the observation illumination light is once converged in the vicinity of the photographing light source 15, reflected by the mirror 16, and passes through the relay lenses 17 and 18, the diaphragm 19 and the relay lens 20. Then, the observation illumination light is reflected by the peripheral part (region around the hole part) of the perforated mirror 21 and illuminates the fundus oculi Ef via the objective lens 22. The optical filter unit 23 will be described later.

  The fundus reflection light of the observation illumination light is refracted by the objective lens 22, passes through a hole formed in the central region of the aperture mirror 21, passes through the dichroic mirror 55, passes through the focusing lens 31, and then goes through the dichroic mirror. 32 is reflected. Further, the fundus reflection light passes through the dichroic mirror 33, is reflected by the mirror 35, and forms an image on the light receiving surface of the image sensor 37 by the condenser lens 36. The image sensor 37 detects fundus reflection light at a predetermined time interval, and generates and outputs an electrical signal (image signal).

  The dichroic mirror 33 combines an optical path that passes through the image sensor 37 and an optical path that passes through an LCD (Liquid Crystal Display) 38. The dichroic mirror 33 may be configured to be retracted from these optical paths. In that case, the observation illumination light is guided to the image sensor 37 without passing through the dichroic mirror 33. The optical filter unit 34 will be described later.

  The imaging light source 15 outputs flash light (also called strobe light or instantaneous light). The imaging light source 15 is constituted by, for example, a xenon lamp or an LED. The light (imaging illumination light) output from the imaging light source 15 is applied to the fundus oculi Ef through the same path as the observation illumination light. The fundus reflection light of the imaging illumination light is guided to the dichroic mirror 32 through the same path as the observation illumination light.

  When the fundus reflection light is infrared light, the fundus reflection light is reflected by the dichroic mirror 32 and detected by the image sensor 37 through the same path as the observation illumination light. On the other hand, when the fundus reflection light is visible light, the fundus reflection light passes through the dichroic mirror 32, is reflected by the mirror 40, and is detected by the image sensor 43 by the condenser lens. The optical filter unit 41 will be described later.

  The optical filter units 23, 34, and 41 will be described. Each optical filter unit 23, 34, 41 is provided with optical filters for various purposes. Examples of the optical filter include those for fluorescent photography and those for red-free photography. Examples of optical filters for fluorescence photography include those for spontaneous fluorescence photography (FAF), those for fluorescein fluorescence photography (FA), and those for indocyanine green photography (ICG). The optical filter is not limited to these, and any optical filter may be used as long as it is used for various photographing techniques in the ophthalmic field.

  As a specific example, a fluorescent photographing filter will be described. The optical filter unit 23 is provided with an FAF exciter filter, an FA exciter filter, and an ICG exciter filter. Each of these exciter filters can be inserted into and removed from the optical path of the illumination optical system 10. The optical filter unit 34 is provided with a FAF barrier filter. This barrier filter can be inserted into and removed from the optical path connecting the dichroic mirror 32 and the image sensor 37. The optical filter unit 41 is provided with an FA barrier filter and an ICG barrier filter. These barrier filters can be inserted into and removed from the optical path connecting the dichroic mirror 32 and the image sensor 43, respectively.

  The LCD 38 displays various visual targets such as a fixation target and a visual acuity measurement target. The fixation target is a target for fixing the eye E to be examined, and is used when observing or photographing the fundus oculi Ef. In addition, it may replace with LCD38 and may provide the internal fixation target comprised including LED.

  Further, the fundus photographing apparatus 1 is provided with an alignment optical system 50 and a focus optical system 60 as in the conventional fundus camera. The alignment optical system 50 generates a target (alignment target) for aligning the apparatus optical system with respect to the eye E (alignment in the xy direction). The focus optical system 60 generates a visual target (split visual target) for focusing on the fundus oculi Ef.

  The light (alignment light) output from the LED 51 of the alignment optical system 50 is reflected by the dichroic mirror 55 via the apertures 52 and 53 and the relay lens 54, passes through the hole portion of the aperture mirror 21, and the objective lens 22. Is projected onto the cornea of the eye E.

  The corneal reflection light of the alignment light is projected onto the light receiving surface of the image sensor 37 via the same optical path as the fundus reflection light of the observation illumination light. A light reception image (alignment target image) by the image sensor 37 is displayed together with the observation image. The user performs alignment by performing the same operation as that of a conventional fundus camera. The alignment may be automatically performed by analyzing the position of the alignment target image and moving the optical system.

  When performing the focus adjustment, the reflecting surface of the reflecting rod 67 is obliquely provided in the optical path of the illumination optical system 10. The light (focus light) output from the LED 61 of the focus optical system 60 passes through the relay lens 62, is separated into two light beams by the split target plate 63, passes through the two-hole aperture 64, and is reflected by the mirror 65. The light is once focused on the reflecting surface of the reflecting bar 67 by the condenser lens 66 and reflected. Further, the focus light passes through the relay lens 20, is reflected by the perforated mirror 21, and forms an image on the fundus oculi Ef by the objective lens 22.

  The fundus reflection light of the focus light is detected by the image sensor 37 through the same path as the cornea reflection light of the alignment light. The light reception image (split target image) by the image sensor 37 is displayed together with the observation image. The fundus photographing apparatus 1 performs focusing by analyzing the position of the split target image and moving the focusing lens 31 and the like, as in the conventional case. Further, manual focusing may be performed while visually confirming the split visual target image.

  Reference numeral 70 denotes a light receiving element for detecting occurrence of blinking of the eye E. This light receiving element is, for example, a photodetector. This blink detection process is performed based on the intensity of reflected light of observation illumination light by the eye E, for example, as in the prior art. The light receiving element 70 monitors the intensity of the reflected light from the eye E. This is a technique that utilizes the fact that when the eye E blinks, the strength is higher than when the eye E does not blink.

  In this embodiment, two imaging devices are used, but the fundus imaging device according to the present invention only needs to have at least one imaging device. The fundus photographing apparatus (fundus camera) may be either a mydriatic type or a non-mydriatic type.

(Control system)
A control system of the fundus imaging apparatus 1 will be described. A configuration example of this control system is shown in FIG. FIG. 2 shows a configuration related to control during FAF imaging.

  Assume that the observation image sensor 37 is a video camera that outputs an analog image signal (video signal). The image sensor 37 is an image sensor having a photoelectric conversion function. The image sensor 37 is configured by, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

  The filter driving unit 23A inserts and removes the optical filter (particularly, the FAF exciter filter) of the optical filter unit 23 with respect to the optical path. The filter drive unit 23A includes, for example, a turret plate on which a plurality of optical filters are mounted, and an actuator such as a pulse motor that rotates the turret plate. The filter drive unit 34A inserts and removes the optical filter (particularly the FAF barrier filter) of the optical filter unit 34 with respect to the optical path. The filter drive unit 34A includes an actuator such as a solenoid.

  The control system of the fundus imaging apparatus 1 includes a control board 100, an image board 200, and a board PC300. The monitor 400 is a display device such as an LCD.

(Control board 100)
The control board 100 receives the image signal output from the image sensor 37 and performs various signal processing on the image signal. Further, the control board 100 controls each part of the fundus imaging apparatus 1. In particular, the control board 100 controls the observation light source 11, the imaging light source 15, the focusing lens 31, the filter driving units 23A and 34A, the dichroic mirror 33, the imaging image sensor 43, the LED 51, the LED 61, the reflector 67, and the like. In addition, an electrical signal is input from the light receiving element 70 to the control board 100. The control board 100 includes a branching unit 110, an FI signal generation unit 120, and a control unit 130. The above control is executed by the control unit 130.

  The branching unit 110 transmits the image signal output from the image sensor 37 to the FI signal generation unit 120 and the image board 200, respectively. This image signal is assumed to be an NTSC analog signal. Hereinafter, this analog signal may be referred to as an NTSC signal.

  The FI signal generation unit 120 generates an FI signal based on the image signal input from the branching unit 110. The FI signal is a field index signal. In the NTSC system, one frame is composed of two fields (odd field and even field). The FI signal is a signal representing the timing of each field in the NTSC signal. An example of the synchronization relationship between the NTSC signal and the FI signal is shown in FIG. The FI signal generation unit 120 transmits the generated FI signal to the control unit 130. The FI signal generation unit 120 is configured by, for example, a field index circuit (see, for example, JP-A Nos. 05-191670 and 2002-335420).

  The control unit 130 controls the imaging light source 15 based on the FI signal and the like input from the FI signal generation unit 120. Details of this control will be described later. Further, the control unit 130 transmits a notification signal to the board PC 300 at a timing when the optical filter (herein, the FAF barrier filter) is completely inserted into the optical path. This timing corresponds to “insertion timing”. Further, the control unit 130 is provided with a timer having a time measuring function (not shown).

  The image board 200 converts the NTSC signal (analog signal) input from the branching unit 110 into a digital signal, and transmits this digital signal to the board PC 300. The image board 200 includes an A / D conversion circuit.

  In response to the insertion timing notification signal, the board PC 300 sequentially stores frames based on the digital signal from the image board 200 in the image memory 310. Further, the board PC 300 causes the monitor 400 to display a still image based on each frame stored in the image memory 310 and a moving image based on these frames.

  The image selection unit 320 of the board PC 300 analyzes an image (frame) stored in the image memory 310 and selects one of them. As a specific example, the image selection unit 320 obtains the brightness of each image stored in the image memory 310 and selects the image having the maximum brightness. The brightness can be obtained based on the pixel value (luminance value) of the image. At this time, if the luminance values of all the pixels of each image are taken into account, the processing may be prolonged, and therefore only a predetermined portion (for example, a central region) of each image may be analyzed. Further, the brightness of the image can be obtained based on a portion having a large luminance value (for example, a pixel having a maximum luminance value or a pixel having a predetermined threshold value or more). The brightness is not limited to these, and may be an index for evaluating how much brightness the image has (in whole or in part).

  In addition, an image region corresponding to a specific part of the fundus (eg, optic disc, blood vessel, macula) is extracted from each image, and the brightness of the image is evaluated based on the brightness of the image region. Good. Further, the evaluation index for selecting an image is not limited to brightness, and any index (for example, sharpness) for evaluating image quality can be used as the evaluation index.

  In addition, the image memorize | stored in the image memory 310 is not limited to what was acquired using flash light, The image acquired using stationary light may be contained.

  The operation unit 500 is used for operation instructions and information input, and constitutes a user interface together with the monitor 400. The operation unit 500 includes hardware such as a shooting trigger button and various switches. When the monitor 400 or the like is a touch panel display, the operation unit 500 includes the touch panel display and a computer program. The operation content for the operation unit 500 is input to the control board 100 as an electrical signal.

[Operation]
The operation of the fundus imaging apparatus 1 will be described. Here, an example of operation in FAF imaging will be described. In this embodiment, FAF imaging is performed using the imaging light source 15 and the observation image sensor 37. Note that the same processing can be executed in other imaging modes.

  First, as in the prior art, alignment of the optical system with respect to the eye E is performed using the alignment target, and focus adjustment for the fundus oculi Ef is performed using the split target. At this time, the FAF exciter filter in the optical filter unit 23 has a characteristic of transmitting infrared light, and may be inserted in the optical path.

  Hereinafter, it is assumed that the observation light source 11 continues to output steady light, and the image sensor 37 continues to detect the fundus reflection light at a predetermined time interval. That is, it is assumed that the fundus imaging apparatus 1 continues to acquire an infrared moving image (observation image) of the fundus oculi Ef having a predetermined frame rate.

  Here, reference is made to the timing chart shown in FIG. After completing the alignment and focus adjustment, the examiner presses the shooting trigger button (operation unit 500) at a desired timing to instruct the start of shooting (time T1).

  Upon receiving the electrical signal from the shooting trigger button, the control unit 130 controls the drive mechanism (not shown) to retract the dichroic mirror 33 from the optical path, and controls the filter drive unit 34A to insert the FAF barrier filter into the optical path. Is started (time T2). Further, in response to receiving the electrical signal from the shooting trigger button, the control unit 130 starts measuring time by the above-described timer (time T2).

  When the timer counts a predetermined time (predetermined time), the control unit 130 transmits a filter insertion notification signal to the board PC 300 (time T3). This filter insertion notification signal is a signal indicating that the FAF barrier filter has been completely inserted into the optical path. The predetermined time is set to be longer than the time from the start of insertion of the FAF barrier filter until it is completely inserted. This predetermined time can be acquired by actually performing the insertion operation of the FAF barrier filter while measuring the time, for example. When the filter drive unit 34A is a solenoid, the predetermined time (ΔT23 = T3−T2) is set to about 100 ms, for example.

  Incidentally, the image signal from the image sensor 37 is input to the board PC 300 via the branching unit 110 and the image board 200. Receiving the filter insertion notification signal, the board PC 300 stores the frames based on the image signals sequentially input from the image board 200 in the image memory 310.

  The FI signal generation unit 120 generates an FI signal based on each image signal input from the branching unit 110 and sequentially transmits the FI signal to the control unit 130.

  In addition to the FI signal, an electrical signal from the light receiving element 70 is input to the control unit 130. The control unit 130 monitors the occurrence of blinking of the eye E based on this electrical signal. Further, when the photographing light source 15 is a xenon lamp, the control unit 130 monitors the charging state of the charging circuit. The control unit 130 causes the photographing light source 15 to output flash light at the timing when the FI signal is input, no blink is generated, and charging is completed (time T4).

  The time (ΔT34) from the insertion timing (time T3) to the flash emission is, for example, about 30 to 60 ms. Therefore, the time (ΔT24) from the start of insertion of the FAF barrier filter (time T2) to the flash emission is about 130 to 160 ms, for example.

  After the flash emission ends, the control unit 130 starts to retract the FAF barrier filter from the optical path (time T5). When the saving of the FAF barrier filter is completed, the control unit 130 ends the transmission of the filter insertion notification signal (time T6). In response to this, the board PC 300 ends the storage of the frame in the image memory 310.

  It is possible to output the flash light a plurality of times from the insertion start timing (time T3) or from the start of flash emission (time T4) to the end of transmission of the filter insertion notification signal (time T6). .

  By performing the processing as described above, the image memory 310 stores a plurality of frames acquired while the filter insertion notification signal is being notified. The image selection unit 320 analyzes the frame stored in the image memory 310 and selects one of these.

  In the example shown in FIG. 4, frames F1 to F4 are generated and stored in the image memory 310 from time T3 to time T6. The image selection unit 320 analyzes each of the frames F1 to F4 to obtain an index representing the brightness, and selects one of the frames F1 to F4 based on the index. Frames F1, F2, and F4 are images acquired using steady light instead of flash light, respectively. Since the image is taken with the FAF barrier filter inserted, the frames F1, F2, and F4 are dark images. On the other hand, the frame F3 is an image photographed with flash light, and includes a wavelength component corresponding to spontaneous fluorescence, and therefore is brighter than the frames F1, F2, and F4. Therefore, the image selection unit 320 selects the frame F3. Note that the number of frames to be analyzed (that is, the number of frames acquired during the period) is arbitrary, and actually, for example, about 7 or 8 frames are to be analyzed.

  The frame selected by the image selection unit 320 is used for diagnosis as a FAF captured image. Two or more frames may be selected. Further, the selected frame may be displayed on the monitor 400, and the examiner may confirm the suitability. If the displayed frame is not appropriate, the image selection process may be performed again. If an appropriate image is still not obtained, photographing can be performed again.

[Action / Effect]
The operation and effect of the fundus imaging apparatus 1 will be described.

  The fundus imaging apparatus 1 includes an illumination optical system 10 having an imaging light source 15, an image sensor 37, an FAF optical filter (particularly a barrier filter), and a control unit 130. The imaging light source 15 outputs flash light, and the illumination optical system 10 irradiates the fundus oculi Ef with this flash light. The image sensor 37 detects the fundus reflection light of the flash light and generates an image signal. The image sensor 37 corresponds to a “first image sensor”. The FAF barrier filter can be inserted into and removed from the optical path between the imaging light source 15 and the image sensor 37. The control unit 130 controls the output timing of the flash light from the imaging light source 15 based on the insertion timing of the FAF barrier filter in the optical path. The control unit 130 is provided on the control board 100.

  According to such a fundus imaging apparatus 1, it is possible to perform imaging by controlling the output timing of the flash light from the imaging light source 15 based on the insertion timing of the FAF barrier filter. This control can be performed by the existing control board 100. Therefore, according to this embodiment, the operation of the light source and the operation of the image sensor can be synchronized without specially adding hardware such as a relay board. That is, according to this embodiment, it is possible to perform shooting while synchronizing the light source and the image sensor without changing the hardware configuration.

  In addition, the fundus imaging apparatus 1 includes a filter driving unit 34A (driving unit) that inserts and removes the FAF barrier filter with respect to the optical path. Control unit 130 includes a timer that starts measuring time in response to the start of insertion of the FAF barrier filter (time T3). Further, the control unit 130 controls the output of the flash light using the timing when the predetermined time (ΔT23) is measured by the timer as the insertion timing. According to such a configuration, it is possible to output flash light at an appropriate timing. Further, it is not necessary to add hardware such as a sensor for detecting that the FAF barrier filter is disposed in the optical path.

  Further, the control unit 130 causes the photographing light source 15 to start outputting flash light based on the insertion timing of the FAF barrier filter, and causes the flash light to be output a plurality of times. Thereby, a plurality of captured images using flash light are obtained. Therefore, the possibility that an image in which the output timing of the flash light coincides with the detection timing of the image sensor 37 is increased.

  Further, the control unit 130 outputs the flash light a plurality of times after the start of the output of the flash light and before the FAF barrier filter is retracted from the optical path. According to this configuration, it is possible to easily and reliably select an image in which the output timing of the flash light coincides with the detection timing of the image sensor 37. That is, the image to be selected needs to have a high image quality, particularly a sufficiently bright image. In addition, there is a large difference in intensity between flash light and steady light (flash light is brighter). Furthermore, the intensity of the stationary light does not include or includes the excitation wavelength of autofluorescence, even if it is included. Therefore, most of the fundus reflected light of the steady light is blocked by the FAF barrier filter. On the other hand, by using flash light, a self-fluorescent image similar to normal FAF imaging can be obtained. Therefore, it is possible to easily and reliably perform a process of selecting a suitable autofluorescence image from these images. Note that the insertion and withdrawal timings of the FAF barrier filter are controlled by a filter insertion notification signal.

  Further, the fundus imaging apparatus 1 analyzes a plurality of images (that is, frames stored in the image memory 310) based on a plurality of image signals from the image sensor 37 that detects the fundus reflection light of the flash light output a plurality of times. The image selection unit 320 (selection unit) that selects any one of these images is included. Thereby, it becomes possible to automatically select a target image. When the image selection unit 320 is not provided, the plurality of images can be displayed on the monitor 400 and the examiner can select a desired image.

  Further, the image selection unit 320 is configured to obtain the brightness of each of the plurality of images and select an image having the maximum brightness. Thereby, it is possible to automatically select an image with appropriate brightness. Note that the process of selecting an image with the maximum brightness can be said to be particularly effective when a generally dark image is acquired as in, for example, fluorescence photography.

  The image sensor 37 may be a video camera that outputs an analog signal as an image signal. Such a video camera repeats light reception and image signal output at predetermined time intervals, and some video cameras cannot receive a trigger signal for controlling the timing of light reception or the like. According to the present embodiment, even with such a video camera, it is possible to acquire an image in which the output timing of the flash light coincides with the detection timing of the image sensor 37. Even a video camera that can be controlled by a trigger signal can acquire a similar image without using the trigger signal.

  In addition, the fundus imaging apparatus 1 includes a light receiving element 70 (detection unit) that detects occurrence of blinking of the eye E to be examined. The control unit 130 causes the photographing light source 15 to output flash light when the occurrence of blinking is not detected by the light receiving element 70 after the insertion timing of the FAF barrier filter. Thereby, the possibility that an inappropriate image is obtained by blinking can be eliminated. That is, it is possible to reliably acquire a captured image using flash light.

  The illumination optical system 10 includes an observation light source 11 (steady light source) that outputs steady light, and irradiates the fundus oculi Ef with this steady light. The image sensor 37 generates a moving image (observation image) of the fundus by receiving steady-state fundus reflected light at predetermined time intervals and generating an image signal. That is, the image sensor 37 is used for both the acquisition of the FAF captured image and the acquisition of the observation image. Thereby, the configuration of the optical system can be simplified.

[Modification]
The fundus imaging apparatus according to the present invention is not limited to the one described above. A person who intends to carry out the present invention can make arbitrary modifications within the scope of the gist of the present invention. Hereinafter, modified examples of the fundus imaging apparatus of the embodiment will be described. In addition, the description about the component similar to the said embodiment may be omitted. Constituent parts similar to those in the above embodiment are denoted by the same reference numerals.

(First modification)
The insertion timing of the optical filter is not limited to that of the above embodiment. As an example, a sensor that detects that the optical filter is disposed in the optical path can be provided, and the detection timing can be set as the insertion timing of the optical filter. This sensor is, for example, a potentiometer. This sensor detects that the optical filter is disposed in the optical path, and inputs an electric signal to the control unit 130. The control unit 130 performs the same control as in the above embodiment with the timing of receiving the electrical signal from the sensor as the optical filter insertion timing.

  According to such a modification, it can be reliably detected that the optical filter is disposed in the optical path. In this modification, the control means includes a control unit 130 and a sensor.

(Second modification)
Another example of the optical filter insertion timing will be described. The illumination optical system 10 is provided with an observation light source 11 (steady light source) that outputs steady light. The illumination optical system 10 irradiates the Ef fundus with this steady light.

  Further, in this modification, a second image sensor is provided that generates image signals by receiving fundus reflection light of steady light at a predetermined time interval. Note that the second image sensor may be the same as the first image sensor or may be different. Here, it is assumed that these are the same image sensor 37.

  The fundus imaging apparatus according to this modification includes an analysis unit that analyzes a moving image based on an image signal generated by the image sensor 37 and identifies an insertion timing. This analysis means is provided on the control board 100 or the board PC 300, for example. This analysis means is part of the control means.

  An example of processing executed by the analysis unit will be described. Assume that the optical filter is a bandpass filter. The optical filters described in the above embodiments are all bandpass filters. The analysis means monitors the brightness of the moving image. Monitoring the brightness means obtaining the brightness of each frame of the moving image sequentially. The method for obtaining the brightness of the frame is the same as in the above embodiment.

  The analysis unit specifies the timing at which the brightness of the frame is reduced as the optical filter insertion timing. Since the optical filter is a bandpass filter, the intensity of light is reduced by passing through the optical filter. That is, the brightness of the image decreases. Using this phenomenon, the analysis means uses the optical filter insertion timing as the image brightness reduction timing.

  The decrease in the brightness of the frame is detected by an arbitrary method. For example, it can be configured to detect that the brightness of one frame is lower than the brightness of the immediately preceding frame by a predetermined value or more. As another method, it can be configured to detect that the brightness of one frame is equal to or lower than a predetermined threshold.

  In addition to the brightness of the frame, the same processing may be performed by applying any image quality evaluation index as described in the above embodiment.

  According to such a modification, it is possible to specify the insertion timing of the optical filter without adding hardware (sensor) as in the first modification.

(Third Modification)
In the above embodiment, the flash light is output a plurality of times after the start of the output of the flash light and before the optical filter is retracted from the optical path. However, the configuration for outputting the flash light a plurality of times is not limited to this.

  For example, the flash light can be output a predetermined number of times based on the insertion timing of the optical filter. This number is arbitrarily set in consideration of the certainty of the image selection process and the processing time.

  When this configuration is applied, it is desirable to retract the optical filter from the optical path after outputting the flash light a predetermined number of times. This control is executed by the control unit 130. The image selection process and the like can be performed in the same manner as in the above embodiment.

  According to such a modification, it is possible to acquire a desired number of captured images using flash light. Further, it is possible to suitably perform the image selection process.

(Fourth modification)
Another example of the configuration for outputting the flash light a plurality of times will be described. It is possible to repeat the flash light output for a predetermined time from the start of the flash light output. This time is arbitrarily set in consideration of the reliability of the image selection process and the processing time. This control is executed by the control unit 130. The control unit 130 has a timer that starts timing at the start timing of the output of the flash light. Until the time measured by the timer reaches a predetermined time, the control unit 130 causes the photographing light source 15 to repeatedly output flash light. When the measured time reaches a predetermined time, the output of the flash light is stopped.

  According to such a modification, it is possible to acquire the number of captured images using flash light according to a desired time. Further, it is possible to suitably perform the image selection process.

(5th modification)
In the above embodiment, the case of using an analog video camera has been described in detail. However, the present invention can also be applied to an image sensor capable of inputting a trigger signal, particularly a digital camera.

  The image sensor 37 is assumed to be operable based on a control signal input from the outside. In this case, the control unit 130 executes fundus imaging by synchronizing the output timing of the flash light from the imaging light source 15 and the detection timing by the image sensor 37.

  According to such a modification, the light source and the image sensor can be synchronously controlled on condition that an image sensor capable of inputting a trigger signal is used. Therefore, it is not necessary to acquire a plurality of frames or select a suitable image from them as in the above embodiment.

(Sixth Modification)
There may be a time lag between the timing at which the control unit 130 transmits the filter insertion notification signal to the board PC 300 and the timing at which the board PC 300 receives the filter insertion notification signal and starts storing frames. Therefore, after transmitting the filter insertion notification signal, the control unit 130 can prevent the flash light from being output for a time corresponding to a predetermined number of frames. That is, after transmitting the filter insertion notification signal, the control unit 130 can measure the time corresponding to the predetermined number of frames, and can start outputting the flash light after the time has elapsed. The number of frames is arbitrarily set in consideration of information transmission time (transmission speed, etc.) between substrates. For example, the number of frames is one.

1 fundus photographing apparatus 10 illumination optical system 11 observation light source 15 photographing light source 23 optical filter unit 23A filter driving unit 30 photographing optical system 34 optical filter unit 34A filter driving unit 37 image sensor 70 light receiving element 100 control board 110 branching unit 120 FI signal generation Unit 130 control unit 200 image board 300 board PC
310 Image memory 320 Image selection unit 400 Monitor 500 Operation unit

Claims (6)

An illumination optical system that includes a light source that outputs flash light, and irradiates the fundus of the subject's eye with the flash light;
A first image sensor that detects fundus reflected light of the flash light and generates an image signal;
An optical filter that can be inserted into and removed from an optical path between the light source and the first image sensor;
Control means for controlling the output timing of the flash light by the light source based on the insertion timing of the optical filter with respect to the optical path;
Equipped with a,
The illumination optical system includes a stationary light source that outputs stationary light, irradiates the fundus with the stationary light,
A second image sensor that receives the fundus reflection light of the steady light at a predetermined time interval and generates an image signal;
The control means includes analysis means for analyzing the moving image based on the image signal generated by the second image sensor and specifying the insertion timing.
A fundus imaging apparatus characterized by the above. The optical filter is a bandpass filter;
The analysis means monitors the brightness of the moving image and specifies the timing when the brightness is reduced as the insertion timing.
The fundus imaging apparatus according to claim 1. An illumination optical system that includes a light source that outputs flash light, and irradiates the fundus of the subject's eye with the flash light;
A first image sensor that detects fundus reflected light of the flash light and generates an image signal;
An optical filter that can be inserted into and removed from an optical path between the light source and the first image sensor;
Control means for controlling the output timing of the flash light by the light source based on the insertion timing of the optical filter with respect to the optical path;
With
The control means causes the light source to start outputting the flash light based on the insertion timing, and further, after starting the output of the flash light, until the optical filter is retracted from the optical path. Output light multiple times
A fundus imaging apparatus characterized by the above. An illumination optical system that includes a light source that outputs flash light, and irradiates the fundus of the subject's eye with the flash light;
A first image sensor that detects fundus reflected light of the flash light and generates an image signal;
An optical filter that can be inserted into and removed from an optical path between the light source and the first image sensor;
Control means for controlling the output timing of the flash light by the light source based on the insertion timing of the optical filter with respect to the optical path;
With
The control means causes the light source to start outputting the flash light based on the insertion timing, and further causes the flash light output to be repeated for a predetermined time from the start of the flash light output.
A fundus imaging apparatus characterized by the above. An illumination optical system that includes a light source that outputs flash light, and irradiates the fundus of the subject's eye with the flash light;
A first image sensor that detects fundus reflected light of the flash light and generates an image signal;
An optical filter that can be inserted into and removed from an optical path between the light source and the first image sensor;
Control means for controlling the output timing of the flash light by the light source based on the insertion timing of the optical filter with respect to the optical path;
With
The control means causes the light source to start outputting the flash light based on the insertion timing, and causes the flash light to be output a plurality of times.
The image processing apparatus includes a selection unit that analyzes a plurality of images based on a plurality of image signals from the first image sensor that detects fundus reflection light of the flash light output a plurality of times and selects one of the images.
A fundus imaging apparatus characterized by the above. The fundus imaging apparatus according to claim 5, wherein the selection unit obtains the brightness of each of the plurality of images and selects an image having the maximum brightness.

Images