JPH05199998A - Fundus camera - Google Patents

Abstract

PURPOSE:To sharpen the image of the fundus oculi by providing a near IR light image pickup means, reflected light quantity detecting means, contrast stressing means and (or) edge stressing means and stressing a contrast and edge in compliance with the reference detected by the reflected light quantity detecting means. CONSTITUTION:The luminous flux emitted from a light source 1 passes a filter 2 and is made into IR light. This light passes a relay lens 3, a stroboscope light source 4 for photographing and a relay lens 6, is reflected by a bored mirror 6 and is passed through an objective lens 7 so that the fundus oculi Er of the eye E to be examined is irradiated with this light. The reflected light by the fundus oculi Er is passed through the objective lens 7, the bored mirror 6, a focusing lens 8 and an imaging lens 9, is reflected by a spring up mirror 10 and is passed through a field lens 12, a mirror 13 and a relay lens 14 so as to be made incident on a television camera 15. The output of the television camera 15 is inputted as the reflected light quantity of the fundus oculi Er to a contrast stressing circuit 16 where the contrast is stressed. The output of this circuit is inputted to a television monitor 17 and is projected as an image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera used in ophthalmology clinics and mass examinations.

[0002]

2. Description of the Related Art Conventionally, a so-called non-mydriasis fundus camera for photographing a fundus without applying a mydriatic agent has been focusing and positioning by a television camera using infrared light. However, the contrast of the fundus image by infrared light is poor and it is difficult to focus.Therefore, a split luminescent line is projected on the fundus, and the reflected image is observed together with the retinal image so that the luminescent line reaches a predetermined position. The optical axis of and the eye to be inspected are aligned and photographed.

[0003]

However, in the above-mentioned conventional example, since the fundus reflection surface due to infrared light is located deeper than the retina surface, the light entering deeper than the retina surface to be photographed is focused at the time of focusing. You are using The difference between the reflecting surface and the retina surface can be corrected on average, but a slight focus error is unavoidable due to individual differences.

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a fundus camera that sharpens a fundus image by infrared light.

[0005]

A fundus camera according to the present invention for achieving the above-mentioned object is provided with an imaging means for irradiating the fundus with near-infrared light and imaging the fundus, and the near-infrared light of the fundus. A reflection light amount detection means for detecting the reflection light amount, a contrast enhancement means and / or an edge enhancement means are provided, and the contrast enhancement means and / or edge enhancement are performed in accordance with the reflection light amount reference detected by the reflection light amount detection means. The image obtained by the image pickup means is sharpened by operating the means.

[0006]

The fundus camera having the above-described structure has the reflected light amount detecting means, the contrast detecting means and / or the edge enhancing means, and enhances the contrast and / or the edge in accordance with the reference detected by the reflected light amount detecting means. To do.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a configuration diagram of the present embodiment. A filter 2, a relay lens 3, that transmits only infrared light is provided on an optical axis L1 that extends from a light source 1 that illuminates a fundus Er of an eye E to the eye E to be inspected. A shooting strobe light source 4, a relay lens 5, a perforated mirror 6 and an objective lens 7 are provided. On the optical axis L2 behind the perforated mirror 6, a focus lens 8, an imaging lens 9, a flip-up mirror 10 and a film 1 are provided.
1 is provided. A field lens 12, a mirror 13, a relay lens 14, and a television camera 15 are provided on the optical axis L3 in the reflection direction of the flip-up mirror 10. The output of the TV camera 15 is the contrast enhancement circuit 1
6, the output of the contrast enhancement circuit 16 is connected to the television monitor 17, and the other output is connected to the autofocus (AF) circuit 18. The output of the AF circuit 18 is output to the focus lens 8 via the drive motor 19. It is connected.

With such a structure, the light beam emitted from the light source 1 passes through the filter 2 to become infrared light, passes through the relay lens 3, the photographing strobe light source 4, the relay lens 5 and is reflected by the perforated mirror 6. Then, the light passes through the objective lens 7 and irradiates the fundus Er of the eye E to be examined. The light reflected by the fundus Er passes through the objective lens 7, the perforated mirror 6, the focus lens 8, and the imaging lens 9, is reflected by the flip-up mirror 10, and passes through the field lens 12, the mirror 13, and the relay lens 14. It is incident on the TV camera 15. The output of the television camera 15 is input to the contrast emphasizing circuit 16 as the reflected light amount of the fundus Er, the contrast is emphasized, and is input to the television monitor 17 to be displayed as an image.

The television monitor 1 is used as a reference for the amount of reflected light.
Although the video signal of the predetermined area S near the center of the screen of 7 is used, the nipple N of the eye E to be inspected is particularly bright, and thus it is not recommended to use it. That is, instead of photographing the nipple N at the center of the screen, an image signal in an area slightly off the center is used. Further, since the peripheral portion of the screen of the television monitor 17 is a region where a strong amount of reflected light of the cornea is likely to enter, it is preferable not to use it.

On the other hand, when the focusing is performed, it can be performed manually while observing the television monitor 17, but it is preferable to perform the focusing automatically. In this automatic focusing, the video signal whose contrast is emphasized by the contrast emphasizing circuit 16 is differentiated by the AF circuit 18, and the drive motor 19 is moved in the direction of increasing the value.
The focus lens 8 is moved by. When a shutter (not shown) is pressed after focusing is completed, the flip-up mirror 10 jumps up and the strobe light source 4 for photographing emits light, and a fundus image is photographed on the film 11.

FIG. 2 is a graph showing the input / output characteristics of the input signal I and the output signal O with respect to the contrast emphasizing circuit 16. The amount of reflected light without contrast emphasizing is shown by a thick solid line a,
The amount of light reflected from the fundus of ordinary brightness is represented by a thin solid line b, the amount of light reflected from the bright fundus is represented by a thick broken line c, and the amount of light reflected from a dark fundus is represented by a thin broken line d. Here, the contrast of the background of the retinal blood vessels is low when infrared light is used, but the difference is magnified when the contrast is emphasized. The amount of light reflected by the fundus Er also differs depending on the reflectance of the fundus Er, the opacity of the translucent body of the subject's eye E, the amount of light from the lamp, and the like.

FIG. 3 is a waveform diagram showing a part of a blood vessel image signal. FIG. 3 (a) is a signal in which nothing is emphasized, FIG. 3 (b) is a signal in which edges are emphasized, and FIG. 3 (c). Is a signal with enhanced contrast. When the contrast is emphasized as shown in FIG. 3C, visual or photoelectric focusing becomes easy.

FIG. 4 is a block diagram of an embodiment in which a partial reflection surface 22 is provided inside the field lens 12 'and light is received by a photoelectric sensor 23. In this case, the level of the fundus reflected light is obtained from the output of the photoelectric sensor 23, instead of obtaining the reflected light amount reference from the screen of the television monitor 17.

FIG. 5 is a block circuit diagram of the contrast emphasizing circuit 16, and FIG. 6 is a waveform diagram of signals inside the contrast emphasizing circuit 16. The signal d input from the television camera 15 to the contrast enhancement circuit 16 is the synchronization signal separation circuit 2
4 and is separated into a video signal e and a sync signal f. The synchronization signal f is input to the detection position control circuit 25, and the output thereof is used as the reflected light amount detection unit 2 as the timing for detecting the reflected light amount.
Enter in 6. The reflected light amount detection unit 26 detects the reflected light amount according to the timing of the detection position control circuit 25,
The output is input to the subtracter 27, and becomes a signal g obtained by subtracting the amount of reflected light from the video signal e and input to the amplifier 28.
Here, the amplified signal h is input to the adder 29 and becomes the signal i to which the reflected light amount is added, and the clipping circuit 3
Enter 0. The clipping circuit 30 cuts the signal exceeding the video signal level by the signal i, and the cut signal j is again added with the synchronizing signal f by the adder 31,
A signal k with enhanced contrast is output. It should be noted that instead of the reflected light amount detection unit 26 and the detection position control circuit 25 described above, other reflected light amount detection means may be used.

FIG. 7 is a block circuit diagram of an edge enhancing circuit 16 'used in place of the contrast enhancing circuit 16,
FIG. 8 is a waveform diagram of the signals of the respective parts. TV camera 1
The signal d input to the edge enhancement circuit 16 ′ from 5 is input to the synchronization signal separation circuit 24 as in the contrast enhancement circuit 16 and is separated into the video signal e and the synchronization signal f. The video signal e is input to the secondary differentiating circuit 32 and becomes a second-order differentiated signal l, which is input to the inverting amplifier 33. The inverted signal m is input to the adder 34, and the video signal e whose timing is adjusted by the delay device 35 is added to become the signal n. The signal n is input to the adder 36 again, and the synchronizing signal f is added to the signal to output the signal o with the edges emphasized.

The above-mentioned contrast enhancing circuit 16
The edge enhancement circuit 16 'can be used together. Also,
In this embodiment, since the video signal is processed for each scanning line,
In contrast and edge enhancement, only the vertical direction can be emphasized, but the video signal is digitized and stored in the image memory, the horizontal direction is also processed in the same way as the vertical direction, and the data is analogized and output as a video signal. This makes it possible to enhance the horizontal contrast and the edge.

Needless to say, the near infrared light may be used as it is to photograph the film.

[0018]

As described above, the fundus camera according to the present invention has the near-infrared light image pickup means, the reflected light amount detecting means, the contrast enhancing means and / or the edge enhancing means, and is detected by the reflected light amount detecting means. Since the contrast and the edge are emphasized according to the standard, the fundus image becomes sharp.
Further, it becomes possible to accurately correct the difference between the infrared light reflecting surface and the retina surface.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a graph of input / output characteristics of a contrast enhancement circuit.

FIG. 3 is a waveform diagram of a video signal.

FIG. 4 is a configuration diagram of a field lens and a light amount detection unit.

FIG. 5 is a block circuit configuration diagram of a contrast enhancement circuit.

FIG. 6 is a waveform diagram of a signal.

FIG. 7 is a block circuit configuration diagram of an edge enhancement circuit.

FIG. 8 is a waveform diagram of a signal.

[Explanation of symbols]

 1 Light Source 6 Hole Mirror 11 Film 15 TV Camera 16 Contrast Enhancement Circuit 16 'Edge Enhancement Circuit 17 Television Monitor 18 Auto Focus Circuit 23 Photoelectric Sensor

Claims (1)

[Claims] 1. An image pickup means for irradiating the fundus with near-infrared light to image the fundus, a reflected light amount detecting means for detecting a reflected light amount of the fundus by near-infrared light, a contrast emphasizing means and / or edge emphasizing. Means is provided, and the image obtained by the image pickup means is sharpened by operating the contrast enhancing means and / or the edge enhancing means in accordance with the reflected light amount reference detected by the reflected light amount detecting means. Characteristic fundus camera. 1. The fundus camera according to claim 1, wherein a part of the signal obtained by the image pickup means is used for the reflected light amount detection means.