JPS6357058B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ophthalmological equipment alignment device used for aligning an ophthalmic equipment such as a refractometer or a keratometer with an eye to be examined.

[Conventional technology]

Generally, when using ophthalmological equipment, it is necessary to accurately match the front-back, top-bottom, and left-right positions of the eye to be examined. Conventionally, this positioning was usually done while looking at the image of the eye being examined projected by an optical system, and although the device is relatively complex, it is quite cumbersome to operate, and the accuracy is not very good. There are drawbacks.

Heretofore, Japanese Patent Publication No. 53-39123 has been known as a focusing device that detects a focused shape, but this is not intended for three-dimensional positioning.

Furthermore, as a three-dimensional positioning device, a method of projecting detection pattern images alternately from different directions onto the iris of the eye to be examined is disclosed in Japanese Patent Application Laid-open No. 11630/1983; Since this method requires two sets of projection systems, it has the disadvantage of being quite complex in structure.

Furthermore, a positioning device that uses corneal reflection is disclosed in Japanese Patent Application Laid-Open No. 58-97340, but this method requires two sets of light receiving systems, so it is also difficult to avoid complicating the configuration. I can't.

[Purpose of the invention]

An object of the present invention is to provide a positioning device for ophthalmological equipment that allows the above-mentioned three-dimensional positioning to be performed easily and has a relatively simple configuration and good operability and accuracy.

[Summary of the invention]

The gist of the present invention to achieve the above objects is as follows:
comprising a positioning light source, a light receiving optical system including a cylindrical lens element that receives a corneal reflected image of the light source by the subject's eye, and a two-dimensional light receiving element that receives the corneal reflected image via the light receiving optical system, This positioning device for ophthalmological equipment is characterized in that a three-dimensional positional relationship with respect to the eye to be examined is determined based on the position and shape of the corneal reflection image on the light-receiving surface of the two-dimensional light-receiving element.

[Embodiments of the invention]

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

FIG. 1 shows a first embodiment of the present invention, where E indicates an eye to be examined, Ec indicates its cornea, and 1 schematically represents an ophthalmological instrument, which has a built-in positioning device. The eye E to be examined is located on the optical axis O of the optical system 2 of the ophthalmological equipment 1 which is used for the purpose of determining, for example, the refractive index, and is set at a specific distance interval. Here, the alignment device is composed of a light projecting optical system consisting of a light source 3, a projection lens 4, etc., a light receiving optical system consisting of a light receiving lens 5 and a cylindrical lens element 6, and a light receiving element 7 consisting of a photoelectric element. ing.

In FIG. 1, the light beam emitted from the light source 3 is obliquely projected through the projection lens 4 and directed toward the cornea Ec of the eye E to be examined.
A virtual image 3a of the light source 3 is formed at Ec. However, since the projection lens 4 is used to effectively utilize the luminous flux from the light source 3, it can be omitted if the S/N ratio is sufficient.

The light reflected by the cornea Ec appears to be emitted from the virtual image 3a, and a portion of this corneal reflected light is received by a light receiving optical system consisting of a light receiving lens 5 and a cylindrical lens element 6, and is guided to a light receiving element 7. ing. Note that, as shown in FIG. 2, the light-receiving element 7 is composed of a two-dimensional array element in which at least four elements 7a to 7d are arranged in a rectangular shape, and is preferably arranged at an average imaging position of the virtual image 3a.

When using such an optical system, the light receiving element 7
The shape and position of the light beam P on the top are shown, for example, in FIGS. 3a to 3d. That is, the light beams emitted from the cylindrical lens element 6 form mutually perpendicular images at imaging positions in the generatrix direction of the cylindrical lens element 6 and in a direction perpendicular thereto. In the middle, it becomes an ellipse as shown in Figures 3b and c, and at the average imaging position in the middle, it becomes an ellipse.
It becomes circular as shown in Figures a and d. Figure 3a shows that the positional relationship between the ophthalmological equipment and the eye E to be examined is front and rear, left and right,
Figure 3b shows the luminous flux P when both the upper and lower sides coincide.
When the front and rear directions do not match, Figure 3 c similarly does not match the front and rear directions, and when the position shifts in the opposite direction to Figure 3 b, Figure 3 d matches the front and rear direction. However, the case where the center position of the luminous flux is shifted in the vertical direction is shown.

In this way, positioning information can be obtained from the shape and position of the light beam projected onto the light receiving element 7.
As a light receiving element for recognizing this, a two-dimensional array element consisting of at least four elements as illustrated in FIG. 2 is required. Now, if the outputs from the four elements 7a, 7b, 7c, and 7d in FIG.
Vd) - (Vb + Vc), (Va + Vb) - (Vc + Vd), (Va
This corresponds to the output of +Vc)-(Vb+Vd), and all you have to do is move it so that these become zero.

FIG. 4 shows a second embodiment of the invention, in which the same reference numerals as in FIG. 1 represent the same or equivalent parts. In this case, the light beam emitted from the light source 3 passes through the light splitting members 8 and 9 and the optical system 2 and is projected onto the cornea Ec of the eye E to be examined. The reflected light from the cornea Ec is transmitted to the optical system 2, the light splitting member 9,
8 and the cylindrical lens element 6 to reach the light receiving element 7.

In this second embodiment, unlike the embodiment shown in FIG. 1 in which the illumination light beam is obliquely projected onto the axis of the eye to be examined, the illumination light beam is projected perpendicularly. The reason why horizontal and vertical alignment is possible is that the cornea Ec is a convex mirror, and if the horizontal and vertical alignment is incorrect, the corneal reflected image position will change horizontally and vertically. This is because it is displaced in the direction.

In this embodiment as well, the optical system 2 is a part of the optical system used for the original purpose of the ophthalmological instrument 1, but here it also serves as an optical system for positioning. In this case, the number of optical system members can be reduced, but the amount of light obtained is slightly reduced.

The above explanation is only about the detection system of the alignment device, but by controlling the electric motor of the drive system using the alignment signal from this detection system, the ophthalmological equipment 1 can be moved in each direction front and back, left and right, and up and down. You can then bring it to the correct position. In addition, indoor lighting sources may also be reflected by the cornea Ec, so
In order to avoid this effect, the light source 3 for alignment
It is also effective to use a light emitting diode or the like that can blink freely and use it in an appropriate frequency band.

〔Effect of the invention〕

As explained above, the positioning device for ophthalmological equipment according to the present invention can obtain an electrical positioning signal with a relatively simple configuration by utilizing the fact that the cornea of the eye to be examined is a convex mirror. This has the advantage that accurate three-dimensional positioning between the eye and the eye to be examined can be carried out efficiently.

[Brief explanation of drawings]

The drawings show an embodiment of the alignment device for ophthalmological equipment according to the present invention, and FIG. 1 is an optical layout diagram of the first embodiment, FIG. 2 is a front view of a light receiving element,
3A to 3D are explanatory diagrams of the position and deviation direction of the light beam on the light receiving element, and FIG. 4 is an optical layout diagram of the second embodiment. Code 1 is ophthalmological equipment, 2 is optical system, 3 is light source, 4
5 is a projection lens, 5 is a light receiving lens, 6 is a cylindrical lens element, 7 is a light receiving element, 8 and 9 are light splitting members, and P is a light beam.

Claims (1)

[Scope of Claims] 1. A light receiving optical system including a positioning light source, a cylindrical lens element that receives a corneal reflected image of the light source by the subject's eye, and 2. A position for ophthalmological equipment, comprising a two-dimensional light-receiving element, and a three-dimensional positional relationship with respect to the eye to be examined is determined based on the position and shape of the corneal reflected image on the light-receiving surface of the two-dimensional light-receiving element. Aligning device. 2. Claim 1, wherein the two-dimensional light receiving element is composed of at least four elements, and the positional relationship is determined based on the output of each of these elements.
The positioning device for ophthalmological equipment described in Section 1.