JPH0628629B2 - Ophthalmic equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ophthalmologic apparatus, and more specifically, it is possible to photograph an eye to be inspected with an appropriate exposure amount by controlling the light emission amount of a photographing light source with which a subject is irradiated. The present invention relates to an ophthalmologic apparatus such as a fundus camera and a surgical microscope.

(Prior Art) In a fundus camera, which is one of the conventional ophthalmologic apparatuses, it is necessary to photograph a fundus image with an appropriate exposure amount, and the light emission amount of a photographing light source is manually adjusted according to film sensitivity. It was However, it has been difficult to adjust to an appropriate value due to changes over time in the light source for photographing, differences in the reflectance of the fundus of the eye to be examined, and the like. Therefore, an apparatus has been proposed in which the amount of light reflected from the fundus of the eye is photoelectrically detected, and the amount of light emitted from the photographing light source can be automatically controlled based on the output signal.

As an example of this type of device, a plurality of light receiving portions are provided at a position conjugate with the fundus, and so-called average photometry is performed to measure the average brightness of the fundus image by each signal from the plurality of light receiving portions. It is known that it is configured as follows.

(Problems to be Solved by the Invention) However, in this apparatus, since the average photometry is performed, the light emission amount can be appropriately controlled in the case of general fundus image photographing, while the region to be specially photographed (for example, , The papilla, the macula, etc., has the drawback that when taking images that correspond to the brightness of a very small area of the fundus, it is not possible to obtain an appropriate amount of illumination light for that area. Was there.

The present invention solves the above-mentioned problems of the prior art, and not only can perform average photometry, but also can easily perform photometry corresponding to the brightness of a part of the fundus image, so-called spot photometry. It is an object of the present invention to provide an ophthalmologic apparatus which can be performed in accordance with requirements and can obtain an appropriate fundus illumination light amount according to a request.

(Structure of the Invention) Therefore, in the present invention, in addition to the plurality of light receiving elements for performing the average photometry, the center of the field of view of the subject (the same as the center of the observation field of view).
It is characterized in that one light receiving element is arranged in the optical axis and spot photometry is also possible by the signal of the light receiving element at the center of the visual field.

(Effects of the Invention) According to the present invention, in addition to the light emission amount control by average photometry,
The light emission amount control by spot photometry based on the brightness of a partial area of the fundus image can be performed by a simple changeover switch. Further, when performing spot photometry, it suffices to bring the part to be photographed particularly to the center of the observation visual field area, and it is possible to perform appropriate light emission amount control by spot photometry with an extremely simple operation.

(Embodiment) A fundus camera according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows an optical system of the fundus camera, which comprises an illumination system 1 and an imaging system 2 which is orthogonal to the illumination system 1 and faces the eye E to be inspected.

The illumination system 1 includes a condenser lens 8, a ring-shaped slit plate 10, and a relay lens 11, which are sequentially positioned on the illumination optical axis 4 so that the observation light source 16 and the photographing light source 5 are located at the front focal point. . Further, a semi-transparent mirror 12 is arranged between the condenser lens 18 and the ring-shaped slit plate 10, and the observation light source 1 is placed on the incident optical axis 14 tatami of the semi-transparent mirror 12.
6 and a condenser lens 18 positioned so that the observation light source 16 is at the front focal point.

The photographic system 2 includes an objective lens 20, a perforated oblique mirror 22, a focusing lens 24 slidable on the photographic optical axis 6, an imaging lens 26, and a semi-lens in order on the photographic optical axis 6 from the eye E side. A transparent mirror 28 and a camera device 30 are arranged. A 5-element light receiving device 34 is arranged at the fundus image forming position on the reflection optical axis 32 of the semi-transparent mirror 28. The perforated oblique mirror 22 is arranged at a position conjugate with the circular slit plate 10 with respect to the relay lens 11. The objective lens 20 is positioned so that the perforated oblique mirror 22 and the pupil P of the eye E to be examined are conjugated. An image of the fundus F of the eye E to be examined by the objective lens 20 is formed at the position 40.

The camera device 30 includes a film 42, a flip-up mirror 44 arranged in front of the film 42, a focusing screen 48 arranged on a reflection optical axis 46 of the flip-up mirror 44 inserted in the photographing optical axis 6, It includes a reflecting mirror 50 and an eyepiece lens 52.
The film 42 and the focusing screen 48 are arranged so as to be conjugate with the fundus imaging position 40 with respect to the focusing lens 24 and the imaging lens 26.

As shown in FIG. 1, the five-element light receiving element 34 includes the light receiving elements PD ₁ to PD ₄ in the peripheral portion and the light receiving element PD in the central portion.
_It consists of ₅ . On these light receiving elements PD ₁ to PD ₅ , a fundus image 5 including a nipple portion 52 and the like, which are brighter than other parts, is formed.
0 is formed, and each element detects the brightness of the corresponding part of the fundus image 50.

In the above optical system, the photographing light source 5 and the observation light source 16 are selectively turned on, and the ring-shaped slit plate 10 is illuminated by the parallel light flux. The light flux that has passed through the ring-shaped slit plate 10 is reflected by the perforated obliquely arranged mirror 22, passes through the ring-shaped peripheral portion of the eye P to be inspected, and illuminates the fundus F. The light beam reflected by the fundus F passes through the center of the pupil P and passes through the fundus imaging position 4
A fundus image is formed at 0. The light flux that formed this fundus image is
The light passes through the hole of the perforated oblique mirror 22 and reaches the film 42, the five-element light receiving element 34, or the inspector's eye 54.

Subsequently, control of the amount of photographing light based on the 5-element light receiving element will be described. Light receiving elements PD _{1 to} PD constituting the light receiving element
_As shown in FIG. 3, the output current of the amplifier ₅ is
The current and voltage are converted by the amplifiers A _{1 to} A ₅ forming the above circuit and are given to the integrators B _{1 to} B ₅ forming the integrating circuit 102.
The integrators B _{1 to} B ₅ have integrating capacitors C _{1 to} C _5, and switches S _{1 to} S ₅ which are opened by a photometry start signal output from the photographing control unit 104 by a shutter release operation.
And are connected in parallel, and outputs a signal obtained by integrating the outputs of the amplifiers A _{1 to} A ₅ . The integrated outputs of the integrators B _{1 to} B ₅ are applied to _one input terminals of the comparators C _{01 to} C ₀₅ that form the comparison circuit 106, respectively, and the other terminal receives the reference voltage from the reference voltage generation circuit 108. The signal is given. Here, the reference voltage is a voltage obtained by calculating the sensitivity of the film, and the comparators C _{01 to} C ₀₅
Emits an output when the integrated output becomes equal to the reference voltage.

The outputs of the comparators C _{01 to} C ₀₅ are AND circuits D _{1 to} D.
₆ and the OR circuit D ₇ are applied to the signal selection circuit 110. The signal selection circuit 110 includes light receiving elements PD ₁ to PD ₁ .
The PD ₄ is configured to detect the second largest output of the light amount level received by the PD ₄ , and by this, the output of the extremely bright portion (nipple portion) or the dark portion (macular portion) is excluded, that is, The output is averaged. On the other hand, the output of the comparator C ₀₅ is directly input to the photometric switching circuit 112 composed of AND circuits D _{8 to} D ₉ and OR circuit D ₁₀ . The photometry switching circuit 112 is provided with the output of the comparator C _{05 and} the output from the spot photometry selection circuit 116, and is selectively switched by the photometry switching circuit 112 and input to the generation stop control circuit 117.

The strobe 118 which is the photographing light source 5 is connected to the light emission stop control circuit 117 and the light emission start control circuit 120. The light emission start control circuit 120 is for starting the light emission of the strobe 118. The light emission stop control circuit 117 uses the strobe 118 based on the brightness of the second brightest part of the fundus image formed on each of the light receiving elements PD _{1 to} PD ₄ or the brightness of the fundus image 7 formed on the light receiving element PD ₅ . It is for stopping.

Next, the operation of the above circuit will be described. The light emission start control circuit 120 starts the light emission of the strobe 118 based on the signal from the photographing control unit 104 in response to the shutter release operation, and switches the switch S by the signal from the photographing control unit 104.
₁ ~S ₅ is opened, the photometry is started. Here, when spot photometry is not selected by the spot photometry selection circuit 116, the signal selection circuit 110 causes the four light receiving elements P to be detected.
The second detected amount of D _{1 to} PD ₄ is the reference voltage generation circuit 10.
When the reference value output from the No. 8 is exceeded, a light emission stop signal is output, and the light emission stop control circuit 117 causes the flash 118
Light emission is stopped.

On the other hand, when spot metering is selected by the spot metering selection circuit 116, a light emission stop control circuit 117 outputs a light emission stop signal to the strobe 118 when the detection amount of the light receiving element PD ₅ exceeds the reference value. , Strobe 11
The light emission of 8 is stopped.

In the present embodiment, the second largest output of the light amount levels received by the light receiving elements PD _{1 to} PD ₄ is detected and the output is averaged. However, the third largest output is obtained if necessary. To detect objects, or to receive light-receiving elements PD _{1 to} PD
Average photometry may be performed by obtaining the average value of ₄ or the average value of PD _{1 to} PD ₅ .

[Brief description of drawings]

FIG. 1 is an explanatory view showing an array of light receiving elements according to an embodiment of the present invention, FIG. 2 is an optical view of a fundus camera according to an embodiment of the present invention, and FIG. 3 is an embodiment shown in FIGS. It is an example control circuit diagram. E ... Eye to be inspected 1 ... Illumination system 2 ... Imaging system 4 ... Illumination optical axis 6 ... Imaging optical axis 20 ... Objective lens 22 ... Perforated oblique mirror 28 ... Semi-transparent mirror 30 ... Camera Device 34: 5-element light-receiving element PD _{1 to} PD _5: light-receiving element

Claims (2)

[Claims] 1. An illumination system having an illuminating light source for illuminating a subject, a photographing system for photographing a subject image formed by a reflected light flux from the subject, and a subject for receiving the reflected light flux, which is substantially the subject. In an ophthalmologic apparatus having a light receiving unit arranged at a conjugate position and a control unit for controlling the light emission amount of the illumination light source to an appropriate value by a signal from the light receiving unit, the light receiving unit is arranged at the center of the imaging field. And a plurality of second light receiving elements arranged around the first light receiving element, and the control unit controls the light emission amount only by the signal from the first light receiving element. And a second control unit for controlling the amount of light emission based on each signal from the second light receiving element. The first control unit and the second control unit are switchable. An ophthalmologic device characterized in that 2. The ophthalmic apparatus according to claim 1, wherein the ophthalmic apparatus is a fundus camera.