JPH0538330A - Ophthalmic image pick-up device - Google Patents

Abstract

PURPOSE:To provide an ophthalmic image-pick up device which can control light emission so that the quantity of light is prevented from being insufficient or excessive even though an excessive or extremely low reflectivity is detected. CONSTITUTION:A computing part 3 computes a reflectivity of an eye to be examined in accordance with a quantity of observing illumination light and a quantity of light of reflection of an observing illumination light reflected by the eye, and a comparator part 5 determines whether the reflectivity of the eye to be examined is within a predetermined range or not. A control part 6 controls the emission of the observing illumination light in accordance with a result of the determination by the comparator part 5 so as to obtain appropriate exposure light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmic photographing apparatus having an automatic exposure function.

[0002]

2. Description of the Related Art An ophthalmic photographing apparatus observes a subject's eye with observation illumination light and photographs the subject's eye with the photographing illumination light.

This ophthalmic photographing apparatus is equipped with the following automatic exposure function, for example. That is, at the start of the emission of the illumination light for photography, the brightness of the imaging region of the eye to be detected is detected from the reflected light of the illumination light for imaging from the region of the eye to be inspected, and the light is already emitted according to the brightness. The light emission is controlled by stopping the light emission of the illumination light for photography which has started. As a result, the ophthalmologic image capturing apparatus can image the eye to be inspected with an appropriate amount of light with respect to the brightness of the imaged region.

[0004]

As in the present invention, when photographing is performed, the illuminating light for observation and the illuminating light for observation reflected from the photographing region of the eye to be examined are prior to the emission of the illuminating light for photographing. Based on the light amount of the reflected light, the reflectance of the imaging site is obtained, and then, in the exposure method in which the illumination light for photography is emitted with the light amount according to the reflectance, from the start of photometry to the illumination light emission for photography, It takes time to calculate the reflectance and set an appropriate amount of light.

For this reason, for example, even if the eyelids and eyelashes enter the photographing region due to blinking during photometry, the photographing region intended by the examiner enters the screen when the illumination light for photographing is emitted and the normal position is obtained. May occupy. On this occasion,
It is expected that the reflectance when measured with the eyelids will be higher than that of a normal fundus, and the reflectance due to the eyelashes will be lower. If the illumination light for photography is emitted according to these reflectances, and if the fundus part intended by the examiner was returned to the normal position on the screen at the time of emission, the amount of light appropriate for the reflectance by the eyelids Insufficient light may occur, and the amount of light suitable for the reflectance due to eyelashes may result in excessive light.

In the conventional exposure method, the eyelids and eyelashes are photographed in such a case, so that the photographed portion intended by the examiner is not photographed, but in the case of the exposure method of the present invention,
There is a possibility that the fundus part or its vicinity intended by the examiner may be imaged, and at that time, care should be taken so that it is taken as an image that can be used for medical examination.

It is an object of the present invention, in the exposure system of the present invention, when the reflectance of the imaged part calculated from the photometric result is calculated as the reflectance that is too large or too small for the normal fundus for the above reasons. In addition, at the time of emission of illumination light for photographing, even when the imaged part or its vicinity intended by the examiner is repositioned in the screen, in order not to have insufficient light amount due to light amount below a predetermined amount or excessive light amount due to light amount above a predetermined amount, If the calculated reflectance is over or under a predetermined limit value, at least if the fundus is photographed with the amount of light,
It is considered that the captured image has a part that can be used as a reference for diagnosis. Therefore, the present invention provides an ophthalmic imaging apparatus that limits the light emission amount of the illumination light for photography to a predetermined reference light amount when the calculated reflectance is larger or smaller than a predetermined limit value. To do.

[0008]

The present invention has the following means in order to solve such drawbacks. That is, the present invention is based on the light amount of the illumination light for observation applied to the eye to be inspected and the light amount of the reflected light of the illumination light for observation reflected from the eye to be inspected, and a calculating means for calculating the reflectance of the eye to be inspected. , A judgment means for judging whether or not the reflectance of the eye to be inspected is within a predetermined range, and controlling the light emission of the illuminating light for photographing so as to obtain proper exposure based on the judgment result of the judgment means When the calculated reflectance is out of the predetermined range, the control unit controls the light emission amount of the photographing illumination light to a light emission amount corresponding to the center of the predetermined range which is the reference light amount.

[0009]

According to the present invention, the calculating means reflects the reflection of the eye to be inspected based on the light amount of the observation illumination light applied to the eye and the light amount of the reflected light of the observation illumination light reflected from the eye. The rate is calculated, and the determination means determines whether or not the reflectance of the subject's eye is within a predetermined range. The control means controls the emission of the illuminating light for photographing based on the judgment result of the judging means, and when the reflectance calculated by the calculating means is out of the predetermined range, it is a reference light amount. The light emission is controlled to the light emission amount corresponding to the center of the range.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. As shown in FIG. 1, the ophthalmic imaging apparatus according to the present embodiment includes light receiving element units 1 and 2, a calculation unit 3, a reference voltage generation unit 4, a comparator unit 5, and a control unit 6. ing.

The light receiving element section 1 detects the light amount of the illumination light for observation that illuminates the eye to be inspected by the light receiving element 1A, and generates a voltage corresponding thereto.

The light-receiving element section 2 detects the amount of reflected light from the imaged region of the subject's eye by the light-receiving element 2A and generates a voltage corresponding thereto.

The calculation unit 3 reflects the reflected light of the imaged region of the eye to be examined from the voltage corresponding to the light amount of the illumination light for observation from the light receiving element units 1 and 2 and the voltage corresponding to the light amount of the reflected light from the fundus of the eye to be examined. Produces an output voltage corresponding to the rate. At this time, the output voltage increases as the reflectance of the imaging region of the subject's eye decreases, and the output voltage decreases as the reflectance increases.

The reference voltage generator 4 generates a reference voltage for defining the reflectance range. In this embodiment, the size is V1>V2> V in order to set the range of reflectance to five levels.
Generates 6 reference voltages with 3>V4>V5> V6.

The comparator 5 compares the output voltage from the calculator 3 with the reference voltages V1 to V6 from the reference voltage generator 4 to generate a light amount control signal. At this time, the output voltage from the calculation unit 3 is compared at the same time as to where the output voltage falls within four ranges defined by the reference voltage, that is, V1 to V2, V2 to V3, V4 to V5, and V5 to V6. When this output voltage falls within the range of V1 to V2, the terminal 5A of the comparator unit 5 is set to "H" and the other terminals 5B to 5D are set to "L". A light emission amount control signal having such an output pattern is generated. Similarly, when the output voltage of the calculation unit 3 is in the range of V2 to V3, the terminal 5B is set to "H" and the other terminals are set to "L", and when it is in the range of V4 to V5, the terminal 5C is set to "H". , And the other terminals to “L”, and V5 ~
In the case of the range of V6, the terminal 5D is set to "H" and the other terminals are set to "L". When the output voltage from the calculation unit 3 is higher than V1, lower than V6, or in the central reference voltage range V3 to V4, all the terminals 5A to 5D are set to "L". These output patterns are shown in FIG.

The control unit 6 controls the light amount of the photographing illumination light based on the light amount control signal from the comparator unit 5. At this time, as shown in FIG. 2, the control unit 6 emits the illumination light for photographing so that the light amount becomes 36 ws when the output pattern of the comparator unit 5 is “L, L, L, L”. Control.
When the output pattern is "H, L, L, L", the light intensity is 75ws, when the output pattern is "L, H, L, L", the light intensity is 50ws, and the output pattern is "L, L, H, L". The light emission of the photographing illumination light is controlled so that the light amount is 25 ws when the output pattern is “L” and the light amount is 18 ws when the output pattern is “L, L, L, H”.

Next, the operation of this embodiment will be described.

According to the present embodiment, for example, when photographing the fundus of the eye to be inspected, the light receiving element section 1 detects the light amount of the observation illumination light with which the eye to be inspected is irradiated, and generates a voltage corresponding to the light amount. .. Further, the light receiving element unit 2 generates a voltage according to the detected light amount of the reflected light from the imaging region of the subject's eye.

The calculation unit 3 generates an output voltage corresponding to the reflectance of the imaged region of the subject's eye by the voltages of the light receiving element units 1 and 2. This output voltage is compared with the six voltages V1 to V6 generated by the reference voltage generation unit 4 by the comparator unit 5. At this time, if the output voltage V from the calculation unit 3 is V3>V> V4, the output pattern of the comparator unit 5 is “L,
L, L, L ". Based on this output pattern, the control unit 6 controls the emission of the photographing illumination light so that the standard light amount 36ws is emitted.

Similarly, if the reflectance of the imaged region of the eye to be examined becomes smaller than the reference and the output voltage V of the arithmetic unit 3 is V2>V> V3, the output pattern of the comparator unit 5 is "L, H,
L, L ”. Based on this output pattern, the control unit 6 controls the emission of the illumination light for photographing so that the standard light amount is increased by one step to emit light. As a result, as shown in FIG. 2, the emitted light amount of the illumination light for photography becomes 50 ws, and photography close to appropriate exposure is performed. Further, if the reflectance of the imaged part of the eye to be inspected becomes smaller than the reference and the output voltage V is V1>V> V2, the output pattern becomes “H, L, L, L”. Based on this output pattern, the control unit 6 controls the emission of the illuminating light for photographing so that the emission amount increases by two steps from the standard light amount. As a result, the amount of illumination light for photography becomes 75ws.

On the other hand, when the reflectance of the imaged region of the eye to be examined becomes higher than the reference and the output voltage V becomes V4>V> V5 or V5>V> V6, the output pattern becomes "L, L, H, L" or "L, L,
L, H ”. Based on this output pattern, the control unit 6 controls the emission of the illumination light for photographing so that the standard light amount is reduced by one step or two steps. As a result, the light amount of the illumination light for photographing becomes 25ws or 18ws.

Further, for example, when the eye fundus of the eye to be inspected is photographed, if the eyelashes of the eye to be inspected enter the photographing range and the reflectance becomes too small, the output voltage V of the arithmetic unit 3 becomes V with respect to the reference voltage V1.
> V1. At this time, the pattern of the light quantity control signal from the comparator unit 5 is "L, L,
L, L ”. Upon receiving the light amount control signal, the control unit 6 controls the light emission so that the standard light amount 36ws is emitted. Therefore, the light amount of the photographing illumination light becomes equal to that when the fundus corresponding to the reference reflectance is photographed.

Further, for example, when photographing the fundus of the eye to be inspected, if the reflectance becomes excessive due to tears in the eye to be inspected, the calculation unit
The output voltage V of 3 is V <V6 with respect to the reference voltage V1. At this time, the pattern of the light amount control signal from the comparator unit 5 becomes "L, L, L, L". The control unit 6 receives the light amount control signal and controls the light emission so that the standard light amount 36ws is emitted, so that the light amount of the photographing illumination light becomes equal to that when the fundus corresponding to the reference reflectance is photographed.

As described above, in the present embodiment, when the fundus of the eye to be inspected is imaged, the reflectance of the imaged part of the eye to be inspected becomes excessive due to, for example, a nick or eyelid or eyelashes. Since the emission of the illumination light for photographing is controlled so that the standard light amount (36WS in the present embodiment) is maintained even if the light amount becomes too small due to the mixture, it is possible to prevent the light amount of the illumination light for photographing from being excessively small or excessive with respect to the original photographing portion. As a result, it is possible to obtain a map that is easier to use for diagnosis than in the case where the imaging illumination light is changed according to the excessive reflectance or the excessive reflectance as in the conventional case.

In this embodiment, the standard light amount is 36 ws and the other light amounts are 18 ws, 25 ws, 50 ws, and 75 ws, but the light amount of the illumination light for photographing is not limited to these, and another light amount may be used. Of course, the number of stages in the reflectance range can also be increased or decreased by changing the contents of the reference voltage generation unit, the comparator unit, and the control unit.

[0027]

As described above, according to the present invention, when the eye to be inspected is photographed, even if the reflectance of the eye to be inspected is too large or too small, the amount of light set within the center of the predetermined range is set. As described above, the emission of the illumination light for photographing can be controlled, and the photographing of a photograph that cannot be used for ophthalmic diagnosis can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a five-step reference reflectance range.

[Explanation of symbols]

 1, 2 Light receiving element section 3 Calculation section (calculation means) 5 Comparator section (judgment means) 6 Control section (control means)

Claims (1)

[Claims] 1. A calculation for calculating the reflectance of the eye to be inspected, based on the light amount of the illumination light for observation applied to the eye to be inspected and the amount of reflected light of the illumination light for observation reflected from the imaging region of the eye to be inspected. Means, a judging means for judging whether or not the reflectance of the eye to be inspected is within a predetermined range, and controlling the light emission amount of the illuminating light for photographing so as to obtain an appropriate exposure based on the judgment result of the judging means, An ophthalmologic image pickup apparatus comprising: a setting unit that sets a predetermined light emission amount when the reflectance calculated by the calculating unit is out of a predetermined range.