JP2001275980A - Eyeground camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate adjusting of a light irradiating amount of a flash lamp with a simple constitution and to alleviate a photographer and an subject's burdens by facilitating more detailed imaging light amount control. SOLUTION: An eyeground camera images an eyeground image of an eye to be examined by irradiating the eyeground of the eye with an imaging luminous flux from an imaging light source. The camera comprises a high sensitivity imaging element for imaging the eyeground image of the subject's irradiated by the luminous flux, a dimming means for dividing a light emitting time into many by a predetermined step and regulating a photographing light amount by a numerical control, a selecting means for previously selecting the light amount, a storage means for storing the light amount corresponding to the image, and a designating means for designating the light emitting time of the light source by reading the stored light amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera for photographing a fundus image of a subject's eye.

[0002]

2. Description of the Related Art Conventionally, there is known a fundus camera for photographing a fundus image of a subject's eye by illuminating a fundus of the subject's eye by emitting a flash lamp and forming a reflected light beam from the fundus on an imaging surface. In such an apparatus, the photographer appropriately sets an appropriate amount of photographing light according to the state of the patient's eye and photographing conditions, and performs photographing.

[0003] Since the flash lamp varies in the amount of light emission depending on the amount of energy stored in a capacitor (capacitor), it is possible to adjust the amount of photographing light by adjusting the amount of energy stored in the capacitor. For example, a fundus camera that adjusts the amount of energy by switching capacitors having different capacities by a switch or combines a plurality of capacitors and shoots with an appropriate amount of photographing light is generally known.

In addition, the amount of reflected light from the subject is detected, and
A device has been proposed in which the light emission is stopped when the integrated value reaches a predetermined value (predetermined exposure amount) to adjust the amount of photographing light without increasing the number of capacitors.

[0005]

However, in the case of the dimming method using a plurality of capacitors as in the former, a large number of capacitors are required, so that the configuration becomes complicated and the cost increases. Further, the more light amount adjustment such as minute light amount is performed, the more capacitors are required, and the number of photographing light amounts that can be set is limited.

In the case of a dimming method in which the amount of reflected light is detected and the light emission is stopped when a predetermined exposure amount is reached,
Since a detection optical system or the like for detecting the amount of light is required, the configuration becomes complicated and the cost increases. Furthermore, when a fundus image is photographed, the difference in the amount of reflected light flux between the optic papilla and the retina in the fundus image is extremely large, so that the amount of reflected light flux that can be detected by a change in the imaging region (the position of the optic papilla) changes. However, there is a possibility that stable photographing cannot be performed and a photographing light amount intended by the photographer cannot be obtained.

In recent years, it has been required to shoot fine details according to the shooting site and symptoms, and in the latter case, it is possible to set a finer shooting light amount in the latter case.
The finer the setting, the more likely it is that the shooting light amount condition will differ from the previous shooting light amount condition in the case of time-varying shooting, etc. It may put a burden on the examiner.

In view of the above problems of the prior art, the present invention can easily adjust the light emission amount of the flash lamp with a simple configuration, facilitate finer control of the photographing light amount, and reduce the burden on the photographer and the subject. It is a technical object to provide a fundus camera capable of causing the fundus camera to be driven.

[0009]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) In a fundus camera that illuminates the fundus of a subject's eye with a photographing light beam from a photographing light source to photograph a fundus image of the eye to be examined, high-sensitivity imaging for photographing a fundus image of the subject's eye illuminated by the photographing light beam An element, a light control unit that divides a light emission time into a large number in predetermined steps and adjusts a photographing light amount by numerical control, a selecting unit that preselects a photographing light amount, and stores the photographing light amount corresponding to a photographed photographed image. Storage means for reading the stored photographing light amount and instructing the light emission time of the photographing light source.

(2) In the fundus camera according to (1), the instruction means includes a control means for driving and controlling the photographing light source based on the read photographing light amount.

(3) In the fundus camera of (2), the control means has a semiconductor switching element for switching between supply and disconnection of electric power to the photographing light source, and the driving of the semiconductor switching element to control the photographing light source. Is performed.

(4) In the fundus camera according to (2), the light control means can be adjusted in ten or more steps.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to an embodiment and drawings. FIG. 1 is a schematic diagram of an optical system of a fundus camera according to an embodiment of the present invention.

The illumination optical system 1 comprises an observation illumination optical system 2 and a photographing illumination optical system 3. The observation illumination optical system 2 and the photographing illumination optical system 3 are coaxial by a dichroic mirror 15, and are covered by the dichroic mirror 15. The optical system for the optometry E is shared. The observation / photographing optical system 4 includes an observation optical system 5 and a photographing optical system 6. The observation optical system 5 and the photographing optical system 6 are coaxial by a dichroic mirror 25, and extend from the dichroic mirror 25 to the subject's eye E. The optical system is shared.
The illumination optical system 1 and the observation / photographing optical system 4 are coaxial by a perforated mirror 21, and share an optical system on the eye E side with respect to the perforated mirror 21.

Light emitted from a halogen lamp 10 as a light source for observation passes through a condenser lens 11 and is converted into infrared light for observation by an infrared filter 12 which transmits only light in the infrared region. Incident on. The dichroic mirror 15 has a characteristic of reflecting infrared light and transmitting visible light. The observation infrared light is reflected by the dichroic mirror 15 and illuminates the ring slit plate 16. Ring slit image formed by infrared light illumination,
After forming an intermediate image near the opening of the perforated mirror 21 via the relay lens 17a, the mirror 18, the black point plate 19, and the relay lens 17b, the light is reflected so as to be coaxial with the optical axis of the observation / photographing optical system 4. Is done. The ring slit light beam reflected by the perforated mirror 21 is once converged by the objective lens 20 near the pupil of the eye E, and then diffuses to uniformly illuminate the fundus of the eye. At this time, slight reflected light generated when the ring slit light beam enters the objective lens 20 becomes harmful light for observing and photographing the fundus image. It is configured to be absorbed.

The reflected light beam reflected on the fundus by the infrared light illumination enters the dichroic mirror 25 via the objective lens 20, the aperture of the perforated mirror 21, the photographic stop 22, the focusing lens 23, and the imaging lens 24. . The dichroic mirror 25 has a characteristic of reflecting infrared light in the invisible range and transmitting light in the visible range. The infrared light reflected by the fundus is reflected by the dichroic mirror 25, passes through the relay lens 30, and is further reflected by the mirror 31 to be incident on the observation CCD camera 32 having sensitivity in the infrared light region. To form a fundus image.

On the other hand, the visible light emitted from the flash lamp 13 which is a photographing light source passes through the condenser lens 14 and the dichroic mirror 15 and is made coaxial with the optical axis of the observation infrared light beam. The eye fundus is illuminated along the same optical path as the infrared light beam for use.

The reflected light beam at the fundus due to the above-described photographing light beam (visible light) emitted from the flash lamp 13 is, similarly to the infrared reflected light beam for observation, the objective lens 20, the opening of the perforated mirror 21, the photographing diaphragm. 22, Focusing lens 2
3. Dichroic mirror 25 via imaging lens 24
Incident on. Thereafter, the light passes through a dichroic mirror 25 having a characteristic of transmitting light in the visible region, and forms a fundus image on an imaging surface of a photographing CCD camera 26 having sensitivity in the visible region.

The video signals from the observation CCD camera 32 and the photographing camera 26 are input to an image memory / image processing unit 51 and then displayed on a liquid crystal display (LCD) 53 via an image conversion unit 52 (see FIG. 1). 2). LCD53
, An image captured by the observation CCD camera 32 or the imaging camera 26 is automatically or manually switched and displayed.

The focusing lens 23 is movable on the optical axis of the observation / photographing optical system 4 in order to form a fundus image on the image pickup surface of the photographing CCD camera 26 and the observation CCD camera 32. Are located.

The operation of the fundus camera having the above configuration will be described with reference to the schematic diagram of the main part of the control system shown in FIG.

The examiner operates the light amount controller 57 prior to photographing to set the photographing light amount. The light amount controller 57 is, for example, a rotary switch, and can set a photographing light amount value from a maximum setting value to a minimum setting value in a stepwise manner. The control of the photographing light amount based on the setting of the light amount controller 57 will be described later.

After setting the photographing conditions, the examiner performs alignment with respect to the subject's eye while observing the subject's eye image displayed on the LCD 53. The LCD 53 displays an eye image to be inspected by an infrared light beam captured by the observation CCD camera 32. During the alignment, when the fundus image is blurred due to the refraction abnormality of the subject's eye, the focus switch 56 is operated to focus the fundus image while observing the infrared fundus image displayed on the LCD 53. The control unit 50 moves the focusing lens 23 on the optical axis of the observation / photographing optical system 4 based on a signal from the focus switch 56.

When the focusing lens 23 is moved to an appropriate position and the fundus image to be photographed can be observed on the LCD 53, the examiner operates the photographing switch 55 to generate a trigger signal.

The control unit 50 that has received the trigger signal causes the high-voltage generation trigger transformer 61 to generate a trigger voltage via the trigger circuit 60. The flash lamp 13 is excited by the trigger voltage, and emits light when the electric power stored in the capacitor 62 is supplied. At this time,
The semiconductor switching element 63 is in an energized state, and includes IGBT (insulated gate bipolar transistor), GTO (gate turn-off thyristor), F
Various semiconductor switching elements 63 such as an ET (field effect transistor) can be used.

When a predetermined period of time corresponding to a preset photographing light amount value has elapsed from the start of light emission of the flash lamp and before photographing, the control unit 50 drives the semiconductor switching element 63 via the semiconductor driving circuit 64, The power supply to the flash lamp 13 is cut off. This makes it possible to forcibly stop the light emission of the flash lamp 13 during light emission, and to obtain a photographed image with a photographing light amount corresponding to the time from the light emission of the flash lamp 13 to the stop.

The relationship between the setting of the photographing light amount by the light amount controller 57 and the time control of the flash lamp emission will be described with reference to FIG. The level gauge at the bottom of FIG. 3 indicates the set photographing light amount value, which is displayed on the LCD 53 or another part of the apparatus as a guide for the photographer to set the photographing light amount value.

WF indicates a light emission waveform when light is emitted by the total stored power of the capacitor 62, and the photographing light amount value is an integral value of the light emission waveform WF. The set value (level gauge) of the light amount controller 57 at this time is set to level F.

When it is desired to obtain a photographing light amount value that is half of the photographing light amount value of the level F, the photographer adjusts the light amount adjuster 57 to set the level to H (the level gauge is half of the level F). In this case, the position at which the integrated value of the light emission amount from the start of light emission becomes half the integrated value of the level F may be obtained, so that the light emission time TH can be obtained. The control unit 50 can obtain a photographing light amount value that is half of the maximum photographing light amount value by cutting off the power by the semiconductor switching element 63 after a lapse of time TH from the start of light emission of the flash lamp 13.

Similarly, a control time corresponding to the photographing light amount is set within a settable range of the light amount controller 57, and the power is cut off by the semiconductor switching element 63 after the control time has elapsed from the start of light emission of the flash lamp 63. , A desired photographing light amount value can be easily obtained.
In the present embodiment, the photographing light amount value is performed by numerical control based on a ratio to the maximum light emission amount obtained from the capacitance of the capacitor, and it is not always necessary to be able to set the photographing light amount at equal intervals with respect to the maximum light emission amount.

In the above description, the numerical value specified for the number of light quantity setting values is not described (in FIG. 3, the level gauge is set to 16 levels). Is possible, a delicate detail can be photographed depending on the photographing site and the symptom, and the effect of the present invention can be exhibited more effectively.

The control time corresponding to the set photographing light amount value is stored in a memory or the like in advance so that the light amount controller 5
7 can be easily obtained according to the setting. In addition, taking into account that the light emission waveform changes due to deterioration of the capacitor, etc., a light receiving circuit is provided near the flash lamp at the time of device startup or before shooting, and the light emission waveform is detected, and the setting is made based on the detected light emission waveform. It is also possible to provide a calibration (self-diagnosis) function for calculating a photographing light amount and a control time corresponding thereto.

As described above, by setting the control time from the start of the emission of the flash lamp and adjusting the photographing light amount based on the control time, it is possible to easily control the photographing light amount value without providing a plurality of capacitors. In such a case, it is possible to easily cope with a case where finer light amount value setting is required, so that it is possible to photograph even a subtle detail due to a photographing site or a symptom. Further, since a detection optical system such as light amount detection is not required, the cost can be reduced and the configuration can be simplified.

The photographing light beam from the flash lamp 13 whose light emission is controlled by the control section 50 illuminates the fundus of the eye to be examined by following the above-mentioned optical path, and the fundus image is photographed by the photographing CCD camera 26. It is stored in the processing unit 51. The image signal from the image memory / image processing unit 51 is switched under the control of the control unit 50, and the captured image is displayed on the LCD 53.

The photographer confirms that the photographed image displayed on the LCD 53 is an appropriate photographed image, and selects a confirmation button (not shown). The control unit 50 transfers the captured image stored in the image memory / image processing unit 51 to the memory 70 according to a signal from the confirmation button. At this time, the memory 70
Also, the photographing light amount information is stored in correspondence with the photographed image. Further, the photographed image and the photographing light amount information can be stored in a storage medium such as an MO (magneto-optical disk) or a memory card via the external output unit 71. It is also possible to connect to a computer or network for image management with a cable or the like, and to perform output by communication.

By storing the photographing light amount information in association with the photographed image in this manner, when performing the temporal change photographing for the same subject, the previous photographing light amount value is displayed. Accordingly, the setting can be easily performed, and stable shooting can be performed under the same conditions. Also, the memory 7
The control unit 50 may read the previous photographing light amount value based on the photographing information and the photographing light amount value from 0 or an external storage medium and automatically set the photographing light amount value. In the apparatus, the trouble of the photographer can be reduced, and smooth photographing can be performed.

[0038]

As described above, in the present invention,
With a simple configuration, the light emission amount of the flash lamp can be easily adjusted, and finer photographing light amount control can be easily performed. In addition, the burden on the photographer and the subject can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an optical system of a fundus camera according to an embodiment.

FIG. 2 is a schematic diagram of a main part of a control system of the fundus camera according to the embodiment.

FIG. 3 is a diagram illustrating a relationship between setting of a photographing light amount value and time control of light emission.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination optical system 4 Observation / photographing optical system 13 Flash lamp 26 CCD camera for photography 50 Control part 57 Light intensity controller 62 Capacitor 63 Semiconductor switching element 64 Semiconductor drive circuit 70 Memory 71 External output part

Claims (4)

[Claims] 1. A fundus camera for illuminating a fundus of a subject's eye by illuminating a fundus of a subject's eye with a luminous flux from a photographic light source, and a high-sensitivity imaging device for capturing a fundus image of the subject's eye illuminated by the luminous flux. A dimming unit that divides a light emission time into a large number of steps in a predetermined step, and controls a photographing light amount by numerical control, a selecting unit that preselects a photographing light amount, and stores the photographing light amount corresponding to a photographed image. Storage means;
An instructing means for reading out the stored imaging light amount and instructing the light emission time of the imaging light source. 2. A fundus camera according to claim 1, wherein said instruction means includes a control means for driving and controlling a photographing light source based on the read photographing light amount. 3. The fundus camera according to claim 2, wherein said control means has a semiconductor switching element for switching between supply and disconnection of power to said photographing light source, and controls driving of said semiconductor switching element to control said photographing light source. A fundus camera that performs light emission control. 4. The fundus camera according to claim 2, wherein the dimming means is adjustable in ten or more steps.