JPS6138564Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gaze target in an eye refractometer.

An eye refractometer projects a target onto the fundus of the eye to be examined, and adjusts the target by moving it in the optical axis direction while electrically detecting or observing the image formation state. is measured as a corrected diopter power, and the measurement must be performed under the condition of far vision of the eye to be examined. For this reason, the eye refractometer is provided with an optical system for projecting a distant gaze target onto the eye to be examined.

In general eye refractometers, a black dot is provided at the center of the rear surface of the objective lens to prevent internally reflected light from the objective lens from entering the measurement optical system. In the case of projection, the sunspot on the objective lens is projected onto the subject's eye together with the distant gaze target, and there is a risk that the subject will be conscious of this sunspot and exercise self-adjustment. For this reason, conventional eye refractometers are configured to project a distant gaze target through a cold mirror or the like provided in front of the objective lens, that is, between the objective lens and the subject's eye. Although such a conventional arrangement is effective in not making the subject aware of the black spot on the objective lens, it has the disadvantage that the optical system becomes longer due to the cold mirror.

Another arrangement is to tilt the optical axis of the gaze target system with respect to the optical axis of the measurement optical system so that the black spot on the objective lens is out of the field of view while the subject is gazing at the gaze target. This is what I did. However, this arrangement deviates from the ideal of objective optometry, in which the optical axis of the eye to be examined and the optical axis of the measurement optical system are aligned to perform measurements. In particular, with infrared refractometers that now perform measurements using near-infrared light, there is no problem of the subject's eye being dazzled by the measurement light, and the optical axis of the subject's eye is aligned with the optical axis of the measurement optical system. It is strongly recommended that this be done.

Therefore, the present invention provides a distant gaze target in an eye refractometer that does not interfere with the sunspot of the objective lens even when projected coaxially with the optical axis of the measurement optical system, and does not require increasing the size of the device. Its purpose is to.

That is, in the present invention, the distant gaze target has a sunspot pattern that has a larger diameter than the sunspot of the objective lens and is arranged to cover the sunspot,
Since the sunspot on the objective lens is completely enveloped within this sunspot pattern, the risk that the sunspot at the near point will be noticed by the subject's eye is greatly reduced. Preferably, the gaze target has a black ring in addition to the above-mentioned black pattern, and in this case, the subject's attention is particularly focused on the surrounding ring, so that the black spot on the objective lens is not visible to the subject. It will no longer be noticed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the target projection system has a light source lamp 1, a condensing lens 2, a target 3, and a projection lens 4, and the light passing through the lens 4 is as follows: The light is reflected by the reflecting mirror 5 and the perforated mirror 6 and projected onto the eye E by the objective lens 8 along the measurement optical axis 7, forming a target image on the fundus of the eye. The measurement optical system includes an imaging lens 9 and an eyepiece 1 placed behind the perforated mirror 6 on the optical axis of the objective lens.
0, the light from the target image of the fundus passes through the objective lens 8 and the hole in the perforated mirror 6 and is focused on 11 points by the imaging lens 9, which are observed through the eyepiece 10. When the target 3 is projected by infrared light, the photocathode of the image pickup tube is placed at position 11.

The gaze target projection system includes a light source 12 and a condenser lens 1.
3. It has a gaze target 14 and a projection lens 15, and the light passing through the projection lens 15 is reflected by a half mirror 17 between the reflection mirror 6 and the perforated mirror 6 and the objective lens 8, and the light passes through the objective lens 8. It reaches the eye E to be examined. A black dot 8a for absorbing internally reflected light is provided at the center of the rear surface of the objective lens 8, and this black dot has a circular shape with a diameter α as shown in FIG. 2a. As shown in FIG. 2b, the gaze target 14 consists of a black dot circular pattern 14a in the center and a ring portion 14b outside of the black dot circular pattern 14a. The black circular pattern 14a has a diameter larger than the diameter of the black dot 8a,
And it is projected so as to completely cover the black spot 8a.
Therefore, the light that illuminates the sunspot 8a on the objective lens disappears, and the sunspot pattern 1 as the gaze target disappears.
Only 4a will be visible. Furthermore, if the ring portion 14b is provided outside the black pattern 14a, the objective lens black spot 8a, which may appear extremely thin within the black pattern 14a, will be further removed from the subject's consciousness. Of course, in the present invention, the outer ring portion of the gaze target is not essential, and the black pattern 14a is not limited to a circular shape.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an optical system of an eye refractometer showing an embodiment of the present invention, FIG. 2a shows an objective lens sunspot, and FIG. 2b shows an example of a gaze target.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A target projection system for projecting a measurement target onto the fundus of the examinee's eye through an objective lens;
In an eye refractometer, the eye refractometer includes a measurement optical system that measures a target image of the fundus through the objective lens, and a gaze target system that projects a distant gaze target onto the eye to be examined through the objective lens. 1. A gaze target for an eye refractometer, characterized in that a black spot is formed in the center of the eye refractometer, and the gaze target has a black pattern having a larger diameter than the reflective sunspot and arranged to cover the black spot. (2) In the above item 1, the gaze target in the eye refractometer has a black ring formed outside the black pattern.