JPH0233250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for measuring the interpupillary distance necessary for fitting a spectacle lens.

[Prior Art] When preparing eyeglasses, it is important to accurately align the center of the pupil with the optical center of the lens. If these do not match, problems such as prism formation will occur. Since the eyeball does not gaze at only one point, the main optical axis of the lens must be aligned with the optical axis of the corresponding eyeball under the average viewing distance (hereinafter referred to as working distance). Must be. For this purpose, it is necessary to measure the interpupillary distance (the distance between the optical centers of eyeglass lenses is generally expressed as the interpupillary distance). Conventionally, as a device for measuring the interpupillary distance at a working distance depending on the subject, as described in Japanese Utility Model Application Publication No. 59-26603, a built-in lens is moved to optically measure the gaze distance. Alternatively, a device is known that measures the interpupillary distance at a required gaze distance. FIG. 3 is a structural diagram thereof. This device is a complicated mechanism, requiring linear movement mechanisms such as a gaze distance setting knob, a slide guide 22 for moving the lens 4 in conjunction with the gaze distance setting knob, and a connecting rod 23. In addition, the gaze distance must be set for each individual subject, and if measurements need to be taken with several working distances, such as with a multifocal lens, there is the inconvenience of having to measure from the beginning each time. It was hot. Furthermore, looking into the pupillary distance meter caused instrumental myopia, and the fixation targets in infinity vision were not fused into one image in some cases.

[Object of the Invention] An object of the present invention is to provide an interpupillary distance that can obtain an interpupillary distance at a gaze distance suitable for each individual subject based on the measured interpupillary distance at a gaze distance of one. The objective is to provide a measurement system. Furthermore, another object is to provide an interpupillary distance meter that allows easy fusion of a fixation target.

[Summary of the Invention] In order to achieve the above object, the present invention includes a first optical means for causing a subject to gaze at a fixation target, and a second optical means for causing a virtual image to be formed by entering the corneal surface of the subject's eye. , a measuring means for measuring the distance between the virtual images to obtain data at a gaze distance of 1; an input means for inputting a gaze distance set to obtain a required interpupillary distance; digital interpupillary distance, the digital interpupillary distance comprising: calculation means for correcting the data set and input using the gaze distance, corneal apex distance, and eyeball rotation radius to obtain the interpupillary distance at the gaze distance. It is a total. Even more preferred is a device that sets the fixed gaze distance to a short distance where image fusion is easy. Also, the first optical means and the second optical means
A device in which the optical system of the optical means is shared can also be adopted.

[Embodiments of the Invention] Examples of the present invention will be described based on the drawings. FIG. 1 is a structural diagram of a digital pupillary distance meter which is an embodiment of the present invention, FIG. 2-1 is a front view of its appearance, and FIG. 2-2 is a plan view thereof. Reference numeral 1 denotes a fixation target illumination lamp, which illuminates the fixation target 2. 3
is a mirror. Reference numeral 4 denotes an objective lens, which is designed with the focal length and arrangement taken into consideration so that the fixation target 2 can be seen at the gazing distance. Here, the gaze distance is 1m
However, 1m itself is not important;
It is important to keep the gaze distance short so that the subject can easily fuse the fixation target 2 into one image. The eyepiece 5 is used by the examiner to observe a bright spot formed on the cornea of the subject. 6 and 7 are for positioning with the pupil position when measuring at the hairline,
In order to obtain the value necessary for prescription glasses, the distance between the corneal apex and the corneal apex is equal to the distance between the eyeglass lens and the corneal apex (corneal apex distance) (12 mm for Japanese people). 8,
The 9 pupillary distance measurement knobs are 10 and 11, respectively.
The encoders 24 and 25 are placed under the brush. 12 is a circuit board in which a microcomputer IC 16, a liquid crystal display 13, etc. are incorporated. 14 is a gaze distance setting knob, which is directly connected to the potentiometer 15. A reed switch 17 is a switch for storing the measured interpupillary distance. 18,
19 is an eye to be examined, and 20 is a protective glass. 21 is a diopter correction lens.

With the above configuration, the illumination light that illuminates the fixation target 2 is reflected by the mirror 3, passes through the objective lens 4, and enters the corneal surface. At this time, the corneal surface acts like a convex mirror and forms a virtual image. This virtual image appears as a minute bright spot because the curvature of the cornea is small. If the subject fixates on the fixation target 2, the visual axes of the subject's eyes intersect at the fixation distance,
In this state, a bright spot on the cornea is formed on the corneal apex. The interpupillary distance measuring knobs 8 and 9 are operated sequentially or simultaneously, and the hairlines 6 and 7 are superimposed on the bright spot of the virtual image of the fixation target 2 formed on the cornea of the subject. The brushes 10 and 11 slide on the encoders 24 and 25 in conjunction with the interpupillary distance measuring knobs 8 and 9, and the information from the encoders 24 and 25 is input to the microcomputer 16 as interpupillary distance data. At this time, the reed switch 17 is pressed and the measured interpupillary distance is stored in the memory of the microcomputer 16 (step 33). The gaze distance setting knob 14 for setting the subject's working distance is connected to the potentiometer 1.
The set gaze distance data is input to the microcomputer 16 as a voltage signal (step 34), and is converted into a digital value by the built-in A/D converter. The microcomputer 16 calculates the interpupillary distance based on the stored interpupillary distance and the input gaze distance data (step 35). The interpupillary distance determined in this way is displayed on the liquid crystal display 13.
(Step 36). Since the interpupillary distance is stored in the microcomputer 16, by operating the gaze distance setting knob 14, the interpupillary distance at any gaze distance can be determined.

Next, the principle of calculating the interpupillary distance at an arbitrary gaze distance based on data measured at one gaze distance will be described.

The sweeping movement of the eyeballs for gazing at an object is a rotational movement around a rotation point. . FIG. 6 is a diagram showing the principle of determining the interpupillary distance.

In this case, the following equation holds true between the interpupillary distance (PDm) obtained by measuring at a known gaze distance (Dm) and the interpupillary distance (PD∞) at infinity viewing.

PD∞=PDm+PDm・VD+R/Dm−VD……(a) Formula VD; Distance between corneal vertices R; Radius of eyeball rotation Next, interpupillary distance at infinity (PD∞)
and pupillary distance (PDn) at any gaze distance (Dn)
The following formula holds between .

PDn=PD∞−PD∞・VD+R/Dn+R ………(b) Formula (a) From formula (b), PDn=PDm・(Dm+R/Dm−VD)(Dn−VD/Dn+R) The interpupillary distance is The size of the eyeball, to be exact, depends on the radius of eyeball rotation, but PD∞ = 30mm, VD = 12
If mm, the radius of eye rotation is R = 13 mm and R = 15
The calculated difference from that of mm is about 0.2 mm.
Considering that the measurement accuracy required for eyeglass preparation is generally 0.5 mm for one eye and 1.0 mm for both eyes,
It is suitable for practical use even if the error due to the difference in the radius of eye rotation is ignored.

Further, D∞ is the distance between the corneal vertex and the object point in the state of infinite distance viewing, but in the case of a finite gaze distance, the distance between the corneal vertex and the object point does not exactly match due to the width of the eyeball. However, when the reading distance Dm = 25cm, the angle between the visual axis when viewing at infinity and the visual axis when gazing at an object point is approximately 7 degrees, so ignoring this will not affect the accuracy. Alternatively, the error may be taken into account and corrected in advance when setting the gaze distance.

In this way, according to this embodiment, the gaze distance is fixed at a short distance where the fixed visual acuity marker is likely to fuse, and
From the measurement results, it is possible to calculate and display the interpupillary distance at any gaze distance.

[Effects of the Invention] As is clear from the above description, according to the present invention, the distance between the pupils at an arbitrary gaze distance can be calculated using a simple device based on data on the interpupillary distance at a fixed gaze distance of 1. You can get as much distance as you need.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of one embodiment of the present invention, Fig. 2-1
The figure is a front view of the external appearance of the embodiment shown in Fig. 1, Fig. 2-2 is a plan view of the external appearance of the embodiment shown in Fig. 1, and Fig. 3 is a structural diagram of a conventional gaze distance changing type interpupillary distance system. , 4th
This figure shows a block diagram of the electrical system of the embodiment shown in FIG. 1, FIG. 5 shows a flowchart of the computer section, and FIG. 6 shows a principle diagram for determining the interpupillary distance. 1...Fixation target illumination lamp, 2...Fixation target, 4
...Objective lens, 6,7...Hairline, 8,
9... Interpupillary distance measurement knob, 10, 11... Brush, 14... Gazing distance setting knob, 15... Potentiometer, 16... Microcomputer
IC, 18, 19... Eye to be examined, 24, 25... Encoder section.

Claims (1)

[Scope of Claims] 1. A first optical means for causing a subject to gaze at a fixation target, a second optical means for forming a virtual image by entering the corneal surface of the eye to be examined, and a second optical means for measuring the distance between the virtual images. te1
measurement means for inputting the gaze distance set to obtain the required interpupillary distance; and input means for inputting the gaze distance set to obtain the required interpupillary distance; 1. A digital pupillary distance meter comprising: calculation means for obtaining an interpupillary distance at a gaze distance determined by correcting the distance between vertices and the radius of rotation of the eyeball. 2. The digital interpupillary distance meter according to item 1, wherein the gaze distance in item 1 is a short distance that facilitates image fusion. 3. The digital pupillary distance meter according to item 1, wherein the first optical means and the second optical means share an optical system.