JPH02252437A - Eye refractivity measuring apparatus - Google Patents

Abstract

PURPOSE:To provide the title apparatus having a simple structure, requiring no strict adjustment of an optical system and obtaining high measuring accuracy by forming the reflected image of the target projected on the retina on the two-dimensional detection element of a detection means and binarizing said image by a processing means to reduce information content before operating the same by an operation means. CONSTITUTION:The luminous flux emitted from a light source is projected on the retina Er and the reflected light thereof is reflected by a perforated mirror 4 to be incident to a wedge prism 8 as six luminous fluxes by a six-perforation iris 6 and formed into images on a two-dimensional sensor array 9 at the time of the examination of emmetropia. These formed target images are sent to an image monitor 16 as video signals by a sensor driving circuit 10 and, at the same time, said signals are compared with the threshold value set by an MPU 14 and a D/A converter 15 by a comparator 11 and binarized to be stored in a memory 13 through a memory writing controller 12. The MPU operates the interval between dot images on the basis of the binarized data of the stored target images and the eye refractivity in the corresponding longitude line direction. By this method, the structure of the apparatus becomes relatively simple by the use of a two-dimensional detection element as a detection means and, further, position data utilizable in operational processing are obtained in large quantities and measuring accuracy is not deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an eye refractive power measuring device that objectively keeps the eye refractive power of the eye to be examined constant at 111.

[Prior Art] In a conventional automatic eye refractive power measuring device, for example, a reflected image of an index projected onto the retina of the eye to be examined is separated and projected onto a plurality of one-dimensional sensor arrays via an optical system, and thereby the obtained image is measured. The sieveness information of the projected image is digitized and the refractive power of the eye is determined. Furthermore, an observation optical system and a two-dimensional sensor array are usually separately prepared, and the projection position is adjusted using these.

[Problems to be Solved by the Invention] However, in the conventional example described above, strict adjustment of the optical system is required in order to reliably separate and project the reflected images of the index onto the plurality of sensor arrays. Furthermore, in order to ensure reliable projection, the index needs to have a complicated shape, such as a Y-shape. Furthermore, it requires a plurality of one-dimensional sensor arrays and their driving circuits, as well as a two-dimensional observation sensor array and its driving circuits, resulting in a problem that the structure is complicated and the cost is high.

An object of the present invention is to provide an eye refractive power measuring device that has a simple structure, does not require strict adjustment of the optical system, and has high measurement accuracy.

[Means for Solving the Problems] In order to achieve the above object, the eye refractive power measuring device according to the present invention includes a projection means for projecting an index onto the retina of the eye to be examined, and a reflected image of the index. a detection means for detecting by a two-dimensional detection element, a storage means for binarizing the video signal from the detection means with a threshold value and storing it, and a calculation for calculating the eye refractive power based on the signal obtained from the storage means. It is characterized by having a means.

[Operation] In the eye refractive power measurement device having the above configuration, the reflected image of the index projected on the retina is formed on the two-dimensional detection element which is the detection means, and is converted into 2ffi by the processing means to increase the amount of information. It is then subtracted and then calculated by a calculation means to determine the eye refractive power.

[Example] The present invention will be explained in detail based on illustrated embodiments.

In FIG. 1, a light source 1 consisting of an LED etc., a lens 2,
As shown in FIG. 2, a pinhole diaphragm 3 having an aperture 3a in the center, a perforated mirror 4, and an objective lens 5 are sequentially arranged toward the eye E to be examined. Here, the light source l is the subject's eye E.
The emmetropic retina Er and the aperture 3 are arranged so as to be substantially conjugate with MEp. On the other hand, perforated mirror 4
On the optical axis bent by
A wedge prism 8 and a two-dimensional sensor array 9 are arranged, and the six-hole aperture 6 is substantially conjugate with the pupil Ep, and the two-dimensional sensor array 9 is substantially conjugate with the emmetropic retina Er. here,
The 6-hole aperture 6 is as shown in FIG.

It has six apertures 6a to 6f arranged at six equal points on the circumference centered on the optical axis, and the imitation prism 8 has six apertures corresponding to the six-hole aperture 6 as shown in FIG. It consists of parts 8a to 8f, each of which has the function of bending the light beam in a direction away from the optical axis.

On the other hand, as illustrated in FIG. It is connected. Further, the MPU 14 connected to the memory 13 so as to be able to exchange signals with each other is connected to the memory write controller 12.
It also provides an output to the D/A converter 15, and furthermore the D/A converter 15.
The output of the /A converter 15 is connected to the other input of the comparator 11. Further, a video monitor 16 is prepared, and the outputs of the sensor drive circuit 10 and the MPU 14 are added together and connected.

In the above configuration, the luminous flux emitted from the light source l reaches the retina E.
The reflected light is reflected by a perforated mirror 4, becomes a 6-tree beam that passes through 6 apertures 6a to 6f in a 6-hole diaphragm 6, and enters a wedge prism 8. The zero-point images 5a-5F that form images 5a-3f shown in FIG. 6 on the two-dimensional sensor array 9 correspond to the apertures 6a-6f of the six-hole diaphragm 6, and the intervals between the one-point images Sa and Sd are wide. The eye refractive power in the radial direction connecting the holes 6a and 6d is expressed by the point images Sb, Se and the point images Sc and Sf in the radial direction connecting the apertures 6b and 6e and the radial direction connecting the apertures 6c and 6f, respectively. These index images 5a-Sf formed on the two-dimensional sensor array 9 are output as a video signal by the sensor drive circuit 10.This video signal is transmitted to the video monitor 1.
At the same time, it is sent to MPU 14.6. ! - It is compared with the threshold value set by the D/A converter 15 and the comparator 11 and is binarized, and the memory write controller 12
The data is stored in the memory 13 via. The MPU 14 calculates the intervals between the point images Sa, Sd, etc. based on the stored binary data of the index image, and the corresponding eye refractive power in the radial direction is given. If the eye refractive power in the three radial directions is known, it is possible to determine the refractive power of the eye to be examined, including astigmatism, which changes sinusoidally with respect to the radial direction. The calculated measurement values are displayed on the video monitor 16 together with the index image, and these operations are controlled by the MPU 14.

Furthermore, in optometry for hyperopic eyes, etc., the conjugate relationship between the two-dimensional sensor array 9 and the retina Er is broken, so the index image obtained on the two-dimensional sensor array 9 is the point image Sa' to S shown in FIG.
This produces a blur like t゛. In such a case, the amount of light per unit area of the sensor decreases, and the measured value becomes more susceptible to the influence of surrounding noise, but the point image Sa''~ required for measurement
When detecting the center position of Sf', conversely, point image Sa'~
By increasing the area of S "", the effect of averaging becomes more pronounced and accuracy is maintained.

Instead of the six point images Sa' to Sf°, a ring image R as shown in FIG. 8 may be projected onto the two-dimensional sensor array 9. In this case, the diameter and ellipticity of the ring image R may be arbitrary gives the radial eye refractive power of. By using this method,
The eye refractive power in any radial direction can be measured simply by changing the arithmetic control by the MPU 14 using software without changing the device.

In addition, if the threshold value for binarization can be set to an arbitrary value using software depending on the eye being examined, it will be possible to cope with changes in the brightness of the index due to differences in retinal reflectance, diopter, etc. .

[Effects of the Invention] As explained above, the eye refractive power measuring device according to the present invention has the following effects:
By using a two-dimensional detection element as the detection means, the structure of the device is relatively simple, and moreover, a large amount of positional information that can be used for calculation processing can be obtained.

1!11 There is no deterioration in the constant accuracy, and the amount of information can be reduced by binarizing and storing the brightness information of the detected image, and even if it is two-dimensional information, old memory can be used. Not needed.

[Brief explanation of drawings]

The drawings show an embodiment of the eye refractive power measuring device according to the present invention,
Figure 1 is a configuration diagram of the optical system, Figure 2 is a front view of a pinhole diaphragm, Figure 3 is a front view of a 6-hole diaphragm, Figure 4 is a front view of a mock prism, and Figure 5 is a block of the electric circuit. Circuit configuration diagram, Figure 6 is an explanatory diagram of the projected image on the detection means in emmetropic eye examination, Figure 7 is an explanatory diagram of the projected image on the detection means during hyperopic eye examination, and Figure 8 is an illustration of the projected image on the detection means during hyperopic eye examination. It is an explanatory view of a ring image. Symbol l is the light source, 3 is the pinhole diaphragm, 6 is the 6-hole diaphragm, 8
9 is a wedge prism, 9 is a two-dimensional sensor array, 11 is a comparator, 12 is a memory write controller, a roller, 13 is a memory, 14 is an MPU, 15 is a D/A converter, and 16 is a video monitor. Figure 111

Claims (1)

[Claims] 1. Projection means for projecting an index onto the retina of the eye to be examined, detection means for detecting the reflected image of the index using a two-dimensional detection element, and binarization of the video signal from the detection means using a certain threshold value and storage. 1. An eye refractive power measuring device comprising: a storage means for calculating an eye refractive power; and a calculation means for calculating an eye refractive power based on a signal obtained from the storage means.