JP2968540B2 - Ophthalmic equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ophthalmologic apparatus such as an auto-refractometer, a tonometer, and a fundus camera used in an ophthalmic clinic or the like.

[Prior Art] As a conventional alignment apparatus for ophthalmic instruments, Japanese Patent Application Laid-Open
As disclosed in Japanese Patent Application Laid-Open No. 62-192200, when the working distance of the subject's eye matches the working distance of the auto-alignment device, a strobe light is emitted, or in a tonometer, reflection from the anterior segment is performed by a single photoelectric sensor. It is known that, when a light beam is received and a light beam having a predetermined light amount or more is received, it is detected that a corneal reflected light beam is received, and air is emitted.

[Problems to be Solved by the Invention] However, in the above-described conventional example, the allowable distance between the actual position of the eye to be inspected and the position at which the eye to be inspected is to be aligned is, for example, about ± 0.07 mm in the non-contact tonometer in the optical axis vertical direction.
As described above, since an auto-refractometer or the like requires ± 0.3 mm or more, the above-described auto-alignment device of the tonometer has a small allowable range and cannot be used for anything other than a non-contact tonometer. Further, in order to increase the allowable range, a method of enlarging the area of a conventional single photoelectric sensor can be considered. The corneal reflected light beam is, for example, about 100 times the light amount of the reflected light beam from the eyelid. Therefore, when the light is received by a single photoelectric sensor having a small area, the received light amount is signal-processed or the examiner observes the corneal reflected light. Although the image can be detected, the alignment is greatly deviated when receiving light with a single photoelectric sensor having a large area, and the area occupied on the photoelectric sensor is reduced when the reflected light beam from the eyelid is received on the photoelectric sensor. The size of the photoelectric sensor becomes large and the corneal reflection image cannot be detected based on the amount of received light. For this reason, the allowable range of the alignment cannot be increased, so that the examiner must first perform the coarse adjustment before performing the automatic adjustment of the fine adjustment.

In addition, when the subject is difficult to fix the position of the subject's eye in a nystagmus patient, an infant, an elderly person, or the like, accurate alignment cannot be performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ophthalmology in which the allowable range of alignment can be increased and the eye to be inspected can be accurately positioned even when the position of the eye to be inspected such as a nystagmus patient, an infant, or an elderly person is difficult to fix. It is to provide a device.

[Means for Solving the Problems] In an ophthalmologic apparatus according to the present invention, a point light source illuminating at least a cornea of an anterior segment of a subject's eye, and an optical system for imaging the anterior segment on a CCD having a plurality of photoelectric regions. A threshold level is set for the output of the photoelectric region in order to distinguish the corneal reflection image included in the anterior segment image from the reflected light from the eyelid, and the photoelectric device generates an output equal to or higher than the threshold level. It is characterized in that a two-dimensional alignment state of the subject's eye is detected based on the region.

[Operation] The ophthalmologic apparatus having the above-described configuration obtains the position of the subject's eye from the position of the region that has generated an output of a predetermined level or more among the plurality of regions of the photoelectric sensor.

[Example] The present invention will be described in detail based on an illustrated example.

FIG. 1 shows a configuration diagram. On the optical axis P1 of the objective lens 1 located in front of the subject's eye E, in order from the objective lens 1 side,
A cylindrical lens 2 having a refractive power in a direction perpendicular to the paper surface, and a photoelectric sensor 3 composed of a one-dimensional CCD in which pixels are divided into a plurality of regions having the same size as a corneal reflection image are arranged. Is provided at an conjugate position with the alignment light source 4 or the photoelectric sensor 3 for alignment away from the optical axis P1.

The light beam from the alignment light source 4 is incident on the eye E,
The light is reflected by the cornea Ec and reaches the cylindrical lens 2 via the objective lens 1. As shown in the cylindrical lens 2 and the photoelectric sensor 3 viewed from the direction of the optical axis P1 in FIG. Is reflected by the cylindrical lens 2, and as shown by the light intensity on the photoelectric sensor 3 in FIG. 3, a corneal reflection image C is received in any region 3a of the photoelectric sensor 3. Then, an electric signal proportional to the amount of light received in each region of the photoelectric sensor 3 is output from the photoelectric sensor 3, and a threshold is set for this output, and only signals exceeding the threshold are detected. ing. That is, when the amount of light received in the area of the photoelectric sensor 3 exceeds a certain threshold, it is detected that the light is received.
If the threshold value of this signal is set by utilizing the fact that the light amount of the light is considerably large, only the corneal reflection image C can be detected without detecting the reflection image other than the cornea Ec. For example, the eye E is displaced from the optical axis P1, and the reflected light from the eyelids
, The photoelectric sensor 3 outputs an electric signal but does not detect that the light is received. After the position of the corneal reflection image C is detected by the above-described method, auto alignment is performed.

FIG. 4 is a block diagram of a second embodiment in which the present embodiment is used for an auto-refractometer, and a refraction value measurement light source 5 and lenses on the optical axis P2 of the eye E to be examined in this order from the measurement light source 5 side. 6, a central aperture stop 7, a perforated mirror 8, a half mirror 9, and an objective lens 1 are provided. On the optical axis P3 reflected by the perforated mirror 8, a 6-hole aperture 10 having six apertures around the periphery is provided. , An objective lens 11, a separation prism 12 composed of six wedge prisms, and a photoelectric sensor 13 composed of a two-dimensional CCD. Further, a half mirror 14 is provided on the optical axis P4 reflected by the half mirror 9, and a two-dimensional CC in which four areas S2 to S5 are arranged around a central area S1 as shown in FIG.
A five-part photoelectric sensor 15 made of D is provided, and the alignment light source 4 is provided at a position conjugate with the five-part photoelectric sensor 15 in the direction reflected by the half mirror 14. The output of each area S1 to S5 of the five-division photoelectric sensor 15 is
The outputs T1 to T5 of the comparator 16 output an electric signal "1" when the light amount of the five-divided photoelectric sensor 15 is equal to or larger than the threshold, and are output when the light amount is equal to or smaller than the threshold. The outputs T1 to T5 of the comparator 16 output an electric signal “0”.

The light beam from the alignment light source 4 is
The eye E is reflected by the half mirror 9 and passes through the objective lens 1.
, Is reflected by the cornea Ec, returns along the same optical path, passes through the half mirror 14, and receives a corneal reflection image C in the area S1, for example, on the five-division photoelectric sensor 15 as shown in FIG.

In the second embodiment, the threshold value is set in advance similarly to the first embodiment, and as shown in FIG.
Since only the output T1 of the comparator 16 connected to the areas S1 to S5 of the five-division photoelectric sensor 15 which has received the light signal outputs the electric signal "1", the position of the corneal reflection image C is detected and the eye E
Of the cornea Ec can be automatically detected.

The light beam from the refraction value measurement light source 5 enters the eye E through the lens 6, the central aperture stop 7, the perforated mirror 8, the half mirror 9, and the objective lens 1, and the light beam reflected by the fundus passes through the same optical path. Reflected by return-hole mirror 8, 8 aperture stop
10. After being separated from the optical axis P3 by the separation prism 12 through the objective lens 11 and received on the photoelectric sensor 13 as shown in FIG. 8, it is possible to measure the refraction value from these six received images. it can. When measuring the refractive value, the cornea Ec of the eye E is aligned and the refractive value is measured while automatically detecting the position of the corneal reflection image C by the above-described method.

Generally, the refractometer performs alignment while displaying and observing the anterior eye portion on a CRT via a CCD camera, so that the electric signal from the central region of the CCD camera is used to position the corneal reflection image C. It may be configured to be used for the detecting means. The extraction of the corneal reflection image is detected based on a signal equal to or greater than the above-described threshold. In addition, in the case of the eye E having astigmatism, it is necessary to measure refraction values in a plurality of radial directions. Therefore, if the configuration is such that this measurement can be performed simultaneously, the measurement can be performed even if the eye E moves. The error can be reduced.

In the above-described embodiment, the alignment apparatus for ophthalmologic instruments of the present invention is used for a refractometer, but may be used for a tonometer, a fundus camera, and the like.

[Effects of the Invention] As described above, the ophthalmologic apparatus according to the present invention can remove the influence of the reflected light from the eyelids and the iris, so that the detection range of the alignment can be enlarged, and the subject can be a nystagmus patient or an infant, Even when the position of the subject's eye such as an elderly person is difficult to be fixed, the position of the subject's eye can be accurately adjusted.

[Brief description of the drawings]

The drawings show an embodiment of the ophthalmologic apparatus according to the present invention. FIG. 1 is a configuration diagram of the first embodiment, FIG. 2 is an explanatory view of a cylindrical lens, a photoelectric sensor, and a corneal reflection image, and FIG. FIG. 4 is an explanatory view of the light intensity of the upper corneal reflection image, FIG. 4 is a configuration diagram of a second embodiment used for an eye refractometer, FIG. 5 is a front view of a five-division photoelectric sensor, and FIG. FIG. 7 is an explanatory view of a corneal reflection image of FIG. 7, FIG.
FIG. 8 is an explanatory diagram of a reflected image on the photoelectric sensor at the time of measuring a refraction value. 1 is an objective lens, 2 is a cylindrical lens, 3,
Reference numeral 13 denotes a photoelectric sensor, 4 denotes an alignment light source, 5 denotes a measurement light source, 7 denotes an aperture, 8 denotes a perforated mirror, 10 denotes a 6-hole aperture, 12 denotes a separation prism, 15 denotes a 5-division photoelectric sensor, and 16 denotes a comparator. .

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-283620 (JP, A) JP-A-59-156324 (JP, A) JP-A-64-34318 (JP, A) JP-A-58-58 97340 (JP, A) JP-A-57-11630 (JP, A) JP-A-61-64228 (JP, A)

Claims (1)

(57) [Claims] An image forming apparatus includes: a point light source that illuminates at least a cornea of an anterior segment of a subject's eye; and an optical system that forms an image of the anterior segment on a CCD having a plurality of photoelectric regions, and is included in the anterior segment image. A threshold level is set for the output of the photoelectric region in order to distinguish the corneal reflection image from the reflected light from the eyelid, and two-dimensional positioning of the subject's eye is performed based on the photoelectric region that generates an output equal to or higher than the threshold level. An ophthalmic apparatus for detecting a state.