JPH042249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ophthalmological imaging device, and more specifically, to an ophthalmological imaging device, more specifically, for imaging a subject with partially different reflectances under optimal exposure conditions for a desired part of the subject depending on the purpose of the imaging. The present invention relates to an ophthalmological imaging device that can perform

Conventional technology In conventional ophthalmological imaging devices, such as fundus cameras, the amount of reflected light from the entire imaging area of the fundus, which is the subject, is detected on average using CdS, etc., and the exposure conditions are determined based on the detected amount of reflected light. It was decided uniformly. However, the fundus of the eye is composed of the papilla, blood vessels, macula, etc., and each of these parts has a different reflectance, so under the uniformly determined exposure conditions described above, some parts may be overexposed or underexposed. It may happen. Particularly in fundus photography of diseased eyes, detailed records of the affected area are medically important, but over- or under-exposure of the affected area has been a major problem.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an ophthalmological photographing device that can photograph a desired part of a subject under optimal exposure conditions depending on the purpose of photographing. .

Structure of the Invention The structure of the present invention provides an ophthalmological photographing apparatus having an illumination optical system that includes a photographing illumination light source and an observation illumination light source and illuminates a subject, and a photographing optical system that photographs the subject. a reflected light amount detection section that detects the amount of reflected light from a subject illuminated by a light source; an illumination light amount detection section that receives light from the observation illumination light source without passing through the subject; the reflected light amount detection section and the illumination. The ophthalmologic photographing device includes a fog light amount determination section that determines the exposure amount for photographing according to the output of the light amount detection section.

Embodiment Hereinafter, a fundus camera which is an embodiment of the present invention will be described based on the drawings. The fundus camera is composed of an optical system consisting of a photographing optical system 1, a finder system 4, and an illumination optical system 8, and a signal processing system consisting of a reflected light amount data detection system 100 and a data processing system 200.

As shown in FIG. 1, the photographing optical system 1 of the eye camera includes an objective lens 10 arranged sequentially from the side of the eye E on the optical axis 2 of the eye E to be examined, and a pupil E _P of the eye E. A fundus system of the subject's eye, which includes a diaphragm 12 arranged near a conjugate position, a focusing lens 14 that moves on the optical axis to adjust the focusing state of the image of the fundus _ER of the subject's eye, an objective lens 10, and a focusing lens 14. It consists of an imaging lens 16 that forms an afocal light beam of an image, and a film 18 that is placed at a position where a fundus image of the eye to be examined is formed.

The finder system 4 of the fundus camera includes an oblique flip-up mirror 20 that is tiltably disposed between a relay lens 16 and a film 18, a field lens 22 that is sequentially disposed on the reflection optical axis 6 of the mirror 20, and a fixed mirror 24. , an imaging lens 26 that re-images the fundus image 17 of the subject's eye on the light receiving surface of a TV camera 28, and a TV camera 28.
The field lens 22 is placed near the fundus image 17 of the subject's eye formed by the imaging lens 16 to make the image 17 bright. The output signal of the TV camera 28 is sent to a TV monitor 30, and the TV monitor 30 forms a fundus image 31 of the subject's eye on a cathode ray tube. When the diagonal flip-up mirror 20 is in the position shown by the solid line in FIG.
On the other hand, when the camera 28 is at the position shown by the dotted line, an image of the fundus of the subject's eye is formed on the film 18 and can be photographed.

The illumination optical system 8 includes a diagonal perforated mirror 3 disposed immediately in front of the aperture 12 of the photographic optical system 1 on the eye E side.
2, a light source 46 for observation illumination arranged sequentially on the reflective optical axis 9 of 2, a condensing lens 44 for condensing the light beam from the light source 46 onto a ring slit 38 (to be described later), a heat shielding filter 42 for absorbing heat rays, and a heat shielding filter 42 for photographing. It consists of a flash tube 40 which is a light source, a ring slit 38 having a donut-shaped transmission part, a condensing lens 36, and a relay lens 34 which forms an image of the ring slit 38 approximately in the vicinity of the position of the diagonal perforated mirror 32. The light beam from the illumination optical system 8 is reflected by the oblique perforated mirror 32 and reaches the eye E through the objective lens 10. An illumination light amount detection element 48 is arranged near the observation illumination light source 46.

As shown in FIG. 2, the signal processing system forms an exposure control signal corresponding to proper exposure from the signal obtained by the TV camera 28, and includes a reflected light amount data detection system 100 and a control calculation processing system 300. and a data processing system 200 including.

The reflected light amount data detection system 100 includes a horizontal/vertical synchronizing signal separation circuit 102 and a timing pulse generator 1.
04, write address signal generator 106, A/D
It is composed of a converter 108 and a frame memory 110, and has a function of detecting and storing reflected light amount data, which is the basis for determining the exposure amount, from the output signal of the TV camera 28.

The horizontal/vertical synchronizing signal separation circuit 102 extracts a horizontal synchronizing signal from the output signal of the TV camera 28 and outputs it to the timing pulse generator 104, and extracts a vertical synchronizing signal and outputs it to the control signal forming section. The timing pulse generator 104 generates a timing pulse based on a horizontal synchronization signal in response to a generation start signal from a control signal forming section 310, which will be described later. Therefore, the timing pulse is synchronized with the output of the TV camera 28. Write address signal generator 106
generates a write address signal based on the write clock pulse and sends it to frame memory 110.
Output to. The A/D converter 108 A/D converts the output of the TV camera 28, ie, a signal corresponding to the amount of reflected light from the object, according to the timing of the output pulse of the timing pulse generator 104, and outputs the A/D converter to the frame memory 110. Therefore frame memory 1
10 sequentially stores the output of the A/D converter 208 based on the write address signal.

The data processing system 200 includes a control calculation processing system 30
0, read address signal generator 202, switch 2
04, Photographing condition setting device 50, A/D converter 208
and a comparator 210. The control arithmetic processing system 300 includes a brightest and darkest data detection unit 302,
It is composed of a boundary value calculation section 304, an averaging processing section 306, a light amount fluctuation compensating section 308, and a control signal forming section 310.

The read address signal generator 202 outputs a signal for sequentially outputting the data stored in the frame memory 110 to the switch 204 based on the control signal from the control signal forming section 310. Switching inside 20
4 outputs the output data of the frame memory 110 based on the control signal from the control signal forming section 310 to the comparator 210 or the brightest and darkest data detecting section 30.
Alternately send to 2. That is, normally, the above output data is first sent to the brightest and darkest data detection section 302, and on the other hand, after the comparator 210 has a boundary value set by the boundary value calculation section 304, the above output data is sent to the comparator 210. .

The photographing condition setting device 50 specifies which brightness part of the fundus should be properly exposed, and the input mode includes, for example, bright part, intermediate part,
Whether it is a method that uses a three-choice selection switch for dark areas, or a disease name selection switch that determines the appropriate brightness of the subject to be exposed for each disease, such as bright areas, intermediate areas, or dark areas. good. The imaging conditions set here are output to the comparator 210,
From the viewpoint of processing, it is preferable that the output mode be a binary code.

The comparator 210 compares a first boundary value Vs ₁ or a second boundary value Vs 2 obtained by a boundary value calculation unit 304, which will be described later, with the switch ₂ according to the setting conditions of the imaging condition setting device 50.
04 and outputs only the light amount data that meets the set conditions. That is, the comparator 204 outputs the light amount data V that satisfies V>Vs ₁ when the bright area is set by the photographing condition setting device 50, and outputs the light amount data V that satisfies V>Vs ₁ when the intermediate area is similarly set.
The light amount data V that satisfies <V<Vs ₂ is output, and similarly when a dark area is set, the light amount data V that satisfies Vs ₂ >V is output.

The A/D converter 208 A/D converts the output signal from the illumination light amount detection element 48 that receives light from the illumination light source 46 and outputs it to the light amount fluctuation compensator 308 . By the way, the illumination light source 46 can vary the amount of light in order to observe the fundus under suitable illumination conditions. On the other hand, the amount of light emitted by the light bulb, which is the illumination light source 46, decreases due to aging, but when this light amount fluctuation occurs, the light amount fluctuation compensation unit compensates for the light amount fluctuation and always allows proper exposure photography. 308. As a result, even if changes occur over time, appropriate exposure can always be achieved.

The control calculation processing system 300 forms exposure control signals and performs data calculation processing. The brightest and darkest data detection unit 302 detects the brightest data and the darkest data of the reflected light amount data received from the frame memory 110 via the switch 204, and sets the boundary value setting unit 304.
At this point, the width of the reflected light amount data of the fundus can be detected.

A boundary value calculation unit 304 calculates a boundary value from the output of the brightest and darkest data detection unit 302 in accordance with the settings of the imaging condition setting unit 50, and sends this result to the comparator 210.
Output to. Here, the brightest and darkest data detection unit 30
2, the brightest light amount data V _{nax and} the darkest light amount data detected in step 2 are set as V _nio , and on the other hand, the shooting condition setting device 50 sets the appropriate exposure areas to the bright area, intermediate area, and dark area as described above.
Categorize and set by type. Boundary value calculation unit 304
are the boundary values Vs ₁ , Vs ₂ Vs ₁ = 2/3 (V _nax - V _nio ) + V _nio = 2/3 V _nax + 1/3 V _nio Vs ₂ = 1/3 (V _nax - V _nio ) + V _nio = 1 /3V _nax +2/3V _nio is output to the comparator 210. That is, if the amount of light in the bright, intermediate, and dark areas is divided into three equal parts of the fundus E _R of the subject's eye, then Vs ₁ calculated using the above formula is the boundary level value between the bright area and the intermediate area, and Vs ₂ indicates the boundary level value between the intermediate area and the dark area.

The comparator 210 selects the frame memory 110 based on the boundary values Vs ₁ and Vs ₂ calculated by the conditions determined by the imaging condition setting device 50.
The outputs are compared and output to the averaging processing section 306.

The averaging processing section 306 averages the plurality of outputs from the comparator 210 and outputs the averaged output to the light amount fluctuation compensating section 308 . This output is a reflected light amount signal of the properly exposed portion corresponding to the set photographing conditions.

The light amount fluctuation compensator 308 includes the A/D converter 208
Based on the output signal of the illumination light amount detection element 48 that has been A/D converted in step 1, compensation for light amount fluctuations in the reflected light amount data that is the output of the averaging processing section 306 is performed. here,
Assuming that the output of the averaging processing unit 306 is Va, the output of the A/D converter 208 is L ₁ , and the preset reference illumination light amount is L ₀ , the light amount data V ₀ that is the basis of exposure control is V ₀ =L. It is determined by ₀ /L ₁ Va.

The control signal forming section 310 receives the light amount data that compensates for the fluctuations in the intensity of light from the light amount fluctuation compensating section 308, and adjusts the data of the film set by a setting device (not shown).
The appropriate exposure time is calculated by taking into account the ASA sensitivity information. On the other hand, after receiving the shutter signal A generated by pressing the shutter release, after the calculated appropriate exposure time has elapsed, an exposure end signal is output to a light emission control circuit 400, which will be described later. The control signal forming unit 310 also outputs a clear signal to the frame memory 110 for clearing the contents of the frame memory 110 at predetermined time intervals, and after generating the clear signal, stores the light amount data in the frame memory 110 again. In order to do this, a generation start signal is output to the timing pulse generator 104 at the timing of the vertical synchronization signal from the horizontal and vertical synchronization signal separation circuit. The control signal forming section 310 further sends a switching signal to the switch 20 to cause the output of the frame memory 110 to be sent to the brightest and darkest data detecting section 302 after the frame memory 110 has newly stored the memory.
4, and after the boundary value calculation unit 304 calculates the boundary value, the switch 204 sends a switching signal that causes the output of the frame memory 110 to be output to the comparator 210.
Furthermore, in order to generate a read address signal, a generation start signal is output to the read address signal generator 202. The above operations allow the signal processing system to operate properly.

The light emission control circuit 400, as shown in FIG.
Consists of a power supply section 410, a light emitting section 420, a trigger section 430, and a commutation section 440, and receives the shutter signal A from the shutter release and the control calculation processing system 30.
The light emission of the flash discharge tube is controlled by the exposure stop signal B starting from 0.

The power supply unit 410 includes an AC power supply 412, a diode bridge 414, a main capacitor C ₁ , and a diode.
It consists of D ₁ and coil L ₁ . The AC voltage of the AC power supply 412 is converted to a DC voltage by the diode bridge 414, and is supplied to the main capacitor _C1 , and also to the light emitting section 420 and the commutation section 440 via the parallel circuit of the diode D and the coil _L1 . Supplied.

The main capacitor _C1 supplies a large current to the flash discharge tube Xe when it emits light, and its capacity is determined according to the amount of light emitted by the flash discharge tube Xe.
The coil _L1 is for suppressing instantaneous current, and the diode _D1 is for preventing backlash.

The light emitting unit 420 includes a flash discharge tube Xe and a thyristor.
It consists of a series circuit of SCR ₁ and resistor R ₁ .
The gate of thyristor SCR ₁ receives the shutter signal corresponding to the operation of the shutter release via resistor R ₁ , and when the shutter is pressed, the thyristor
SCR ₁ is turned on, and the voltage applied to the light emitting section 420 is applied to the flash discharge tube Xe.

The trigger section 430 includes a coil L ₂ , a capacitor C ₂ ,
It is composed of a thyristor SCR ₂ and resistors R ₂ and R ₃ , and generates a high voltage that prompts the flash tube Xe to start emitting light in response to the shutter signal A. Before shutter operation, thyristor SCR ₂ is OFF and capacitor C ₂
is charged with the polarity shown through the resistor R ₂ and the primary terminal of the coil L ₂ . When the shutter is operated, the shutter signal A obtained through the resistor _R3 turns on the thyristor _SCR2 , which short-circuits the capacitor _C2 , causing a short-circuit current to flow to the primary terminal of the coil _L2 . A high voltage is generated at the secondary terminal of the coil _L2 , and is applied to the trigger terminal and cathode of the flash discharge tube Xe. At this time, since SCR ₁ is also turned on as described above, the flash discharge tube Xe starts discharging.

The commutation section 440 includes a capacitor C ₃ and a thyristor.
It consists of SCR ₃ , resistors R ₄ and R ₅ . The value of the resistor _R4 is selected such that when the voltage supplied from the power supply unit 410 is applied thereto, the current value flowing through it is equal to or less than the holding current of the thyristor _SCR3 . The value of the resistor _R5 is selected appropriately considering the charging time of the capacitor C. capacitor
The capacitance of _C3 is selected to be sufficient to commutate the current flowing through the thyristor _SCR1 , apply a reverse voltage to the thyristor _SCR1 , and change the thyristor _SCR1 to the OFF state, as described later.

In the above configuration, before shutter operation, capacitor C ₃ is connected to both thyristors SCR ₁ and SCR ₃ .
Since it is OFF, it is charged with the polarity shown in FIG. 3 via resistors R ₄ and R ₅ . The shutter is operated, the flash discharge tube Xe starts emitting light,
After a predetermined period of time has elapsed, that is, when the proper exposure amount has been applied to the film, an exposure stop signal B is input from the control calculation processing section 300 to the game of the thyristor SCR ₃ via the resistor R ₆ . As a result, the thyristor SCR ₃ is turned ON, the positive electrode of the capacitor C ₃ is short-circuited to ground, and the current flowing through the thyristor SCR ₁ of the light emitting circuit 420 flows into the capacitor C ₃ .
A reverse voltage is applied to thyristor SCR ₁ , and thyristor SCR ₁ is turned off. On the other hand, when the capacitor _C3 is charged to a polarity opposite to that shown in FIG. 3, no current flows and the flash discharge tube Xe stops emitting light. Since the value of the resistor R ₄ is selected as described above, the thyristor SCR ₃ changes to the OFF state when the flash discharge tube Xe stops emitting light.

A capacitor whose polarity is opposite to that shown in Figure 3 when the flash discharge tube Xe stops emitting light.
C ₃ is charged to the polarity shown in FIG. 3 via resistors R ₄ and R ₅ and returns to its initial state.

Effects of the Invention Since the present invention is configured as described above, the ophthalmological imaging device according to the present invention can photograph a desired part of a subject under optimal exposure conditions depending on the purpose of photographing, making a great contribution to medical science. It is what you do.

[Brief explanation of drawings]

FIG. 1 is an optical diagram of a fundus camera according to an embodiment of the present invention, FIG. 2 is a block diagram of a signal processing system, and FIG. 3 is a circuit diagram of a light emission control circuit 400. 10... Objective lens, 32... Diagonal perforated mirror, 38... Ring slit, 42... Heat protection filter, 100... Reflected light amount data detection system, 102
...Horizontal and vertical synchronization signal separation circuit, 200 ... Data processing system, 202 ... Read address signal generator, 300 ... Control calculation processing system, 302 ... Brightest and darkest data detection section, 304 ... Boundary value calculation Part, 3
10... Control signal forming section, 400... Light emission control circuit.

Claims (1)

[Scope of Claims] 1. An ophthalmological photographing apparatus having an illumination optical system that includes a photographing illumination light source and an observation illumination light source and illuminates a subject, and a photographing optical system that photographs the subject, wherein the observation illumination light source is a reflected light amount detection section that detects the amount of reflected light from an illuminated subject; an illumination light amount detection section that receives light from the observation illumination light source without passing through the subject; the reflected light amount detection section and the illumination light amount detection section. An ophthalmological photographing device comprising: an exposure amount determination section that determines an exposure amount for photographing according to an output of the section.