JPH01158934A - Pupillary distance meter - Google Patents

Abstract

PURPOSE:To easily check the presence of phoria or squint, by arranging a liquid crystal display between an eye to be examined and a fixed target and shielding a single eye by a liquid crystal pattern. CONSTITUTION:A measuring movable mark and a slit light transmitting part for checking an optic axis serve as the liquid crystal pattern of one liquid crystal display. The voltage signals proportional to the moving quantities of pupillar distance measuring knobs 7, 8 are outputted from linear potentiometers 9, 10 in connection with the pupillar distance measuring knobs 7, 8. If the voltage value when a hairline pattern is overlapped with the bright point on the cornea is read, a pupillary distance can be measured. A single eye shield switch 36 is changed over to wholly block the hairline pattern of the liquid crystal display on the side of a single eye and the single eye is shielded.

Description

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

[Prior Art] When adjusting eyeglasses, it is necessary to make the main optical axis of the lens coincide with the optical axis of the corresponding eyeball under the gaze type @ (this is called the working distance) in the average usage state. For this purpose, it is necessary to accurately measure the distance between the optical axes (interpupillary pressure@) of the subject's eyeballs.

When measuring with a pupillary distance meter, it is common to measure with both eyes open, but there are times when it is necessary to shield one eye. For example, if for some reason the eyeballs are too sensitive to make measurements, the eyeballs can be stabilized by distracting one eye.

It is also used to check for the presence of strabismus or strabismus. When the eye to be examined has an abnormality of strabismus or strabismus, if the other eye is occluded, the eye to be examined with the abnormality often moves in an attempt to see the same vision ridge, so this is used to detect this.

FIG. 5 is a structural diagram of a conventional device.

The single-eye shielding mechanism of this pupillary distance meter is implemented by attaching and removing a shielding plate in the optical path of the left and right eyes. By operating a switching lever (not shown) at the bottom of the device, the shielding plate 22 is rotated about the rotating shaft 21 to be inserted into or removed from the optical path.

[Problems with the prior art and purpose of the invention] However, the conventional device has the following problems.

It is certainly a simple shielding mechanism, but in order to make the shielded eye invisible to the examiner and to prevent the optotype from being visible from the shielding eye, the shielding plate must be made considerably large. . Furthermore, since the shielding plate 22 must be rotated about the rotating shaft 21, a space for this is required, which becomes an obstacle to compactness. Another problem is that quick switching is not possible.

In view of the shortcomings of conventional devices, it is an object of the present invention to provide an interpupillary interpupillary system that has a single-eye shielding mechanism that enables quick switching to easily check for the presence or absence of strabismus, strabismus, etc., and that allows the device to be made more compact. The aim is to provide a rangefinder.

[Structure of the Invention] In order to achieve the above object, the present invention includes an optical axis indicating mark forming means for indicating the position of the optical axis of the eye to be examined, and a moving mark for measurement, and the two marks are arranged in a predetermined relationship. In an interpupillary distance meter that can measure the distance between the optical axes of the eyeballs at a predetermined gaze distance by aligning with It is characterized by the provision of means for shielding one eye.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described based on the drawings.

In this embodiment, liquid crystal patterns for measurement moving marks, visual axis checking, and monocular shielding can be formed on one liquid crystal display.

FIG. 1 is a structural diagram of an interpupillary distance meter which is an embodiment of the present invention, and is an embodiment in which the moving mark for measurement and the slit transparent part for checking the visual axis are formed into a liquid crystal pattern of one liquid crystal display. be. Figure 2-1 is its external front view, Figure 2-2
The figure is a plan view thereof.

Reference numeral 1 denotes a lamp for illuminating the visual target 2, which illuminates the visual target 2 from behind. 3 is a mirror.

Reference numeral 4 denotes an objective lens, and its focal length and arrangement are taken into consideration so that the target can be easily seen at the viewing distance. In other words, in this embodiment, the interpupillary distance at an arbitrary working distance can be obtained by fixing the gaze distance and correcting the lens measured at that gaze distance. The gaze distance is short to make it easier.

The eyepiece 5 is used by the examiner to observe a bright spot formed on the cornea of the subject.

6 is a transmissive liquid crystal display. Since the control principle and method of the liquid crystal display itself do not have any features of the present invention, their explanation will be omitted. A large number of patterns approximately equivalent to hairlines are arranged on the display, and one of them is displayed in polarized light as shown in FIG. 3-2. Accuracy can be improved by making the pitch between patterns finer.

Further, the measurement moving mark does not necessarily have to be in the shape of a hairline, but only needs to be able to be aligned.

The movement of the hairline pattern is controlled by inputting a voltage signal output from a linear potentiometer to a microcomputer after A/D conversion, and moving the hair pattern on the liquid crystal display in proportion to this input value.

The distance between the hairline pattern and the corneal apex is set to be equal to the distance between the eyeglass lens and the corneal apex in order to obtain a value necessary for eyeglass prescription.

The interpupillary distance measuring knobs 7.8 and 9.8 are respectively linked with 9° and 10 linear potentiometers, and the linear potentiometers output voltage signals proportional to the operation of the interpupillary distance measuring knobs.

Although the interpupillary distance measuring knob in this embodiment is linked to a linear potentiometer, it goes without saying that a brush type encoder may also be used, or any other device may be used as long as the amount of change can be converted into length.

11 is a circuit board, which is a microcomputer ICl3.
, a liquid crystal display 12 for displaying measurement results, etc. are incorporated.

13 is a gaze distance setting knob, which is directly connected to the potentiometer 14.

The reed switch 6 is for inputting the A/D converted voltage signal of the linear potentiometer to the microcomputer when the bright spot matches the hairline pattern.

Reference numerals 17 and 18 are the eyes to be examined, and 19 and 20 are protective glasses that protect the eyes to be examined.

FIG. 4 is a block diagram of the electrical system of the embodiment shown in FIG.

30 is an A/D converter for the linear potentiometers 9 and 10, and 31 and 32 are drivers. 33 is a buzzer indicating that the reed switch has been pressed. 34 is a battery voltage detector.

35 is a power switch of the device, and 36 is a switch for shielding one eye, which shields light from one eye side of the liquid crystal display. Reference numeral 37 denotes a switch for checking the visual axis, which allows only the light of the hairline portion of the pattern on the liquid crystal display to pass through, and blocks the rest, thereby confirming whether or not the visual axis is in a normal arrangement.

The operation of the apparatus configured as described above will be explained below.

First, the operation of forming a bright spot that indicates the optical axis of the eye to be examined will be described.

The power source 35 is turned on and the subject and the device are positioned in a predetermined relationship. The examiner instructs the subject to gaze at the target.

Illumination light emitted from the light source 1 for illuminating the target target and illuminating the target target 2 is reflected by the mirror 3 and enters the cornea via the objective lens. The corneal surface acts as a convex mirror and forms a virtual image. Since the curvature of the cornea is small, this virtual image appears as a minute bright spot. If the subject is fixating on the same visual target 2, the visual axes of both eyes of the subject will intersect at the gaze distance point, and the bright spot on the cornea will be located on the angle apex.

Thereafter, the interpupillary distance measuring knobs 7.8 are operated either sequentially or simultaneously. In conjunction with the pupillary distance measuring knob 7.8, the linear potentiometer 9.10 outputs a voltage signal proportional to the amount of movement of the pupillary distance measuring knob 7.8. The pupillary distance measurement knob 7.8 is operated to overlap the hairline pattern with the bright spot on the subject's cornea (see Fig. 3-2).

After confirming that they overlap, press the reed switch 16. The hairline pattern on the LCD display is controlled to move in proportion to the voltage signal output from the linear potentiometer, so if you read the voltage value when the hairline pattern overlaps with the bright spot on the cornea, you can see the difference between the pupils. Distance can be measured. The voltage signal at the position where they overlap is input to an A/D converter, converted into a digital signal, and then input to a microcomputer and stored in memory.

The gaze distance setting knob that sets the subject's working distance is linked with a potentiometer, and the set gaze distance data is input to the A/D converter as a voltage signal, converted to a digital signal, and then sent to the microcomputer. is input.

Based on the measured interpupillary distance and input gaze distance data, the microcomputer calculates the pupil opening M at the gaze distance using the following equation.

PDm is the interpupillary distance when the gaze distance Dm is known.

The interpupillary distance at the desired gaze distance Dn is PDn,
VD is the corneal vertex opening @ (calculated as 13 m for Japanese),
R is the radius of rotation of the eyeball, and there is no problem in treating it as a constant due to measurement accuracy.

The interpupillary distance calculated and determined in this way is displayed on the liquid crystal display 12.

After the measurement, the visual axis check switch 37 is pressed.

In the liquid crystal pattern, the position of the hairline pattern when the reed switch 16 is pressed is a transparent portion, and the other portions are shielded from light.

Figure 3-1 is an explanatory diagram of the outline of the visual axis check.
Figure 3 is a schematic diagram of the liquid crystal pattern seen from the optotype side. After measuring the interpupillary distance, fixate the fixation target with both eyes to stabilize the visual axis, and then switch to monocular testing, in which the target can be seen through the slit of the other eye while one eye is occluded. Check for visual axis abnormalities.

This operation may be performed manually or automatically using a microcomputer. Note that the width of the slit does not need to match that of the hairline; it is sufficient to be able to check that it is within an acceptable range.

If an abnormality is recognized through the above operations, move the corresponding pupillary distance measurement knob to align the visual axes.

Next, perform a monocular occlusion test. After reminding the subject to fixate the same visual target again, the single eye shielding switch 36 is switched to completely shield the hairline pattern of the liquid crystal display on the one eye side, thereby shielding one eye. The examiner observes the movement of the credit card immediately after the shielding through the eyepiece lens 5.
(If not, use the shielding switch 36 to switch the eyes to be shielded and do this in the same manner.

Note that the order of the monocular occlusion test is not particularly limited, so it may be performed first, for example.

[Effects of the Invention] As is clear from the above description, according to the present invention, quick switching is possible with a simple mechanism, and the presence or absence of strabismus, strabismus, etc. can be easily checked. Furthermore, since no shielding plate is required, the device can be made more compact.

[Brief explanation of the drawing]

Figure 1 is a structural diagram of this embodiment, Figure 2-1 is an external front view,
FIG. 2-2 is a plan view thereof. Figure 3-1 is an explanatory diagram of the outline of the visual axis check, Figure 3-2 is a schematic diagram of the liquid crystal pattern before and after pressing the visual axis check switch, viewed from the fixation target side, and Figure 4 is a schematic diagram of the liquid crystal pattern before and after pressing the visual axis check switch. The electrical system block diagram, FIG. 5, is a structural diagram of a conventional device. 6...Liquid crystal display 7.8...Pupillary distance measurement measurement knob 9.10.
...Linear potentiometer 36...Switch for one eye shielding

Claims (3)

[Claims] (1) It has an optical axis indicating mark forming means that indicates the position of the optical axis of the eye to be examined, and a moving mark for measurement, and by aligning both the marks in a predetermined relationship, the eyeball can be adjusted at a predetermined gaze distance. An interpupillary distance meter capable of measuring the distance between optical axes, characterized in that a liquid crystal display is disposed between the eye to be examined and the fixation target, and means for shielding one eye with the liquid crystal pattern is provided. Pupillary distance meter. (2) An interpupillary distance meter, characterized in that the liquid crystal display according to claim 1 also forms moving marks for measurement. (3) An interpupillary distance meter, characterized in that the liquid crystal display according to claim 1 or 2 also forms a liquid crystal pattern for checking the visual axis.