JPS628731A - Eye refractive power measuring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an eye refraction measuring device used to measure the refractive values of the eye, such as 1-sphere refraction, degree of astigmatism, and angle of astigmatism.

[Prior Art] In a conventional device of this type, the observation television and the measurement sensor are constructed separately, resulting in a complex structure and relatively high cost.

[Object of the Invention] In order to improve the shortcomings of the conventional device, the object of the present invention is to provide a structural system that divides the screen of a viewing television partially or temporally so that it can be used as a measurement sensor. The object of the present invention is to provide a simple ocular refraction measuring device.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide a television camera that photographs an extraocular image of an eye to be examined, a television monitor that images a video signal from the television camera, and a fundus of the eye to be examined. means for projecting a pattern on the fundus, means for extracting reflected light from the fundus from at least three locations on the pupil of the eye to be examined and guiding the fundus pattern image to an image sensor of the television camera, and determining the positional relationship of the fundus pattern image. The eye refraction measurement apparatus is characterized in that it has means for calculating a refraction value of the eye to be examined based on a signal from the image sensor or a video signal.

[Embodiments of the invention] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows an optical layout diagram of the ocular refraction measuring device according to the present invention, in which E represents the eye to be examined, Er represents the fundus of the eye, and Ep represents the pupil. In front of the eye E to be examined, light splitting members 1. Lens 2. The TV right camera is located. The TV right camera consists of an area sensor array 4 which is a photographing element such as a two-dimensional COD, and an image section 5, and its image video signal is sent to a signal processing section 6 and a TV monitor 7. On the reflection side of the light splitting member 1, a lens 8, a perforated mirror 9, an entrance diaphragm 10, a lens 11, a pattern diaphragm 12, and a measurement light source 13 are arranged in this order. Further, an exit diaphragm 14, an image rotation deflection prism 15, and a lens 6 are arranged on the reflection side of the perforated mirror 9, and the light beam reflected by the perforated mirror 9 is further transmitted through mirrors 17 and 18 to T
It is designed to be incident on the V right camera.

In FIG. 1, light emitted from a measurement light source 13 illuminates a pattern diaphragm 12 arranged at a position conjugate to the fundus of an emmetropic eye. This pattern diaphragm 12 has a pattern 12a in which three slit openings are arranged radially, as illustrated in FIG. A perforated mirror 9 with a hole in the center of the entrance aperture lO1 having a circular aperture 10a in the center. A pattern 12a is projected from the center of the pupil Ep of the eye E to the fundus Er via the lens 8 and the light splitting member l.

A part of the reflected light from the fundus Er is transmitted to the light splitting member 1
, a lens 8, a perforated mirror 9, an exit diaphragm 14 having six apertures 14a to 14f as shown in FIG. A slit image from [31%] is projected onto the area sensor array 4, which is an image sensor. In this embodiment, the incident light flux on the pupil is as shown in FIG.

On the other hand, observation light for positioning travels straight through the light splitting member 1 and forms an image of the anterior segment of the eye E on the area sensor array 4 by the lens 2. In this case, there is no problem even if the light source for external lighting is provided separately from the measurement light source 13. In this embodiment, the observation light and the measurement light are made to enter different parts of the area sensor array 4. However, it is also possible to interpose another light splitting member so that the light is sequentially incident on the same part of the area sensor array 4.The light splitting member 1 may be more efficient if a wavelength-selective guichroic mirror is used. good.

The television camera 3 converts the signal from the area sensor array 4 into an image video signal using the image section 5, and transmits the image video signal to the signal processing section 6 and the television monitor 7 for display. Note that the measurement signal may be directly extracted from the area sensor array 4, in which case a signal for each bit is obtained, resulting in higher accuracy.

The image rotation deflection prism 15 is a combination of an image rotation prism 15' shown in FIG. 6 and a deflection prism 15" shown in FIG. 7. FIG. 8 shows this image rotation deflection prism 15'. 15 and six openings 14 of the injection diaphragm 14.
Six small prisms 15a to 15f corresponding to a to 14f
For example, the aperture 14 of the injection diaphragm 14
The light beam emitted from c enters the small prism 15c, and is totally reflected by the reflecting surface 15C.Since the zero reflecting surface 15C is inclined by 30 degrees with respect to the reflecting surface 15A of the small prism 15a,
The image is rotated by 60 degrees. Opening d of injection aperture 14
are arranged at radial intervals of 60 degrees, and the openings 14c, 1
In order to measure the refraction value in the radial direction connecting 4d, it is sufficient to measure the inclination of the two light beams emitted from this point. In this case, in the case of normal vision, the two light beams become parallel, and by passing through the image rotation deflection prism 15, the movement in the apertures 14c, 14d direction can be changed to the apertures 14a, 14b direction.Similarly, the aperture 14f, The refraction value in the radial direction connecting the openings 14e can also be measured in the radial direction connecting the openings 14a and 14b. The light beams emitted from the apertures 14a and 14b do not need to be rotated, so the small prisms 15a and 15b can be omitted.

The deflecting prism 15'' functions to divide the six images output from the six apertures by appropriate intervals.By appropriately selecting the inclination angle of the end face of the rotating prism 15°, the deflecting prism 15'' and the rotating prism 15' can be integrated.

FIG. 9 shows six images on the area sensor array 4, and each image A to F is formed by the light beams that have passed through the respective apertures 14a to 14f. The refraction values in the two radial directions are obtained from the distances of these three sets of images A, B, and C, and the distances of E and F on the scanning line S, respectively. in general,
It is thought that the refractive value of the eye changes sinusoidally in the radial direction, so if the refractive value in the two radial directions is known, the other radial directions can be calculated, and the spherical refractive power,
It becomes possible to calculate the degree of astigmatism and the angle of astigmatism.

To find the position of each image on the scanning line S, you can set an appropriate level threshold for the video signal and binarize it, or perform A/D conversion on each bit of the signal, store it in memory, and perform calculations. You can take the following method. Furthermore, if signals from a plurality of scanning lines are used for averaging instead of the signal on one scanning line S, the noise is averaged, so that measurement accuracy can be improved.

FIG. 10 shows an entrance diaphragm 10 in a second embodiment, which corresponds to the entrance diaphragm 10 in FIG.
As shown in FIG. 11, the injection aperture 14 has a
Three apertures 14b, 14d, and 14e are provided at positions symmetrical to the aperture of the entrance diaphragm 10 in FIG. 10 and the optical axis.

In this second embodiment as well, the pattern projected onto the fundus Er is the same as that in FIG. 2, but each slit 12a is projected from each opening 10a, 10c, 10f. In this case, the image rotation prism 1 is used as the image rotation deflection prism 15.
5" is not used, and three openings 14b, 14d, 14e are opened.
A deflection prism 15" is used to prevent the images received from the
It is sufficient to provide only

FIG. 12 shows the area sensor array 4 in the second embodiment.
It shows the slit images above, image B is open aloa and 14b, image is aperture 10c' and 14d, image F is open 01
This is due to the light beams passing through 0e and 14f, respectively. When the diopter of the eye E changes, images B, D, and F become straight lines B1
, Dl, and Fl, the refraction values in the two radial directions can be obtained by extracting the signals from the area sensor array 4 on these straight lines and detecting the image position.

Note that an ordinary television camera using an image pickup tube may be used as the television camera, without using an area array sensor.

[Effects of the Invention] As explained above, the ocular refraction measuring device according to the present invention has a simple structure because the observation television and the measurement sensor can be integrated, and the ocular refraction measuring device according to the present invention is small and inexpensive. Obtainable.

[Brief explanation of the drawing]

The drawings show an embodiment of the eye refraction measuring device according to the present invention, and FIG. '1 is an optical layout diagram showing the first embodiment;
Fig. 2 is a front view of the pattern diaphragm, Fig. 3 is a front view of the entrance diaphragm, Fig. 4 is a front view of the exit diaphragm, Fig. 5 is an explanatory diagram of the proper input and output light flux, and Fig. 6 is the image rotation prism. 7 is a sectional view of the deflection prism, FIG. 8 is a sectional view of the rotary deflection prism, FIG. 9 is an explanatory diagram of the fundus pattern image on the area sensor array, and FIG. 10 is the second 111, a front view of the entrance aperture of the embodiment, is a front view of the exit aperture, Fig. 1.
FIG. 2 is an explanatory diagram of a fundus pattern image on the area sensor array. 1 is a light splitting member, 3 is a television camera, 4 is an area sensor array, 5 is an image section, 6 is a signal processing section, 7 is a television monitor, 9 is a perforated mirror, 10 is an entrance diaphragm, 12 is a pattern diaphragm, 13 is a measurement light source, 14 is an exit diaphragm, and 15 is an image rotation deflection prism. Patent applicant: Canon Co., Ltd. Figure 6 Figure 7 Figure 9 Figure 10

Claims (1)

[Claims] 1. A television camera that photographs an extraocular image of the eye to be examined, and a television monitor that images a video signal from the television camera;
means for projecting a pattern onto the fundus of the eye to be examined; means for extracting reflected light from the fundus from at least three locations on the pupil of the eye to be examined and guiding the fundus pattern image to an imaging element of the television camera; and the fundus pattern image. An eye refraction measurement apparatus characterized by comprising means for determining the positional relationship between the two using a signal from the image sensor or a video signal, and calculating a refraction value of the eye to be examined. 2. The eye refraction measuring device according to claim 1, wherein the image sensor is an area sensor array.