JP3636790B2 - Visual function inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a visual function inspection apparatus for inspecting the visual function of an eye to be examined, and more particularly to an apparatus suitable for stereoscopic inspection.
[0002]
[Prior art]
There is known a visual function inspection device that switches and presents various test targets including a visual acuity chart for visual acuity test and inspects the visual function of an eye to be examined.
In this type of apparatus, a polarizing plate is generally used when constructing a stereoscopic target for examining stereoscopic vision, which is one of the important items of visual function inspection. The same target having different polarization axes is shifted left and right by the amount corresponding to the stereoscopic viewing angle in the same plane. The inspection is performed so that the polarizing plate target can be seen separately by both eyes through a polarizing filter.
[0003]
[Problems to be solved by the invention]
However, showing the inspection target to the subject through the polarizing filter in this way means that the inspection is performed in a state different from the daily visual environment, and the visual function of accurate stereoscopic vision is always inspected. That wasn't true.
SUMMARY OF THE INVENTION In view of the above-described drawbacks of the conventional technology, the present invention provides a visual function inspection device that can realize a precise stereoscopic inspection in a state close to the daily vision environment with a simple configuration without using a polarizing plate. Let it be an issue.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is characterized by having the following configuration.
(1) A target for visual function inspection is placed on a target disk, and the target is switched by rotating the disk, and a target switching means for presenting the target target to the subject, and a view reflected by a concave mirror And a space-saving optical system that reflects the light flux from the target toward the eye to be inspected by mirror reflection. In the visual function inspection device, the target disk has the transmission surface of the target disk as a background. A first target having a predetermined black shape provided on the surface of the disk, and an optical distance corresponding to the amount of elevation or sinking of the stereoscopic parallax expected with respect to the first target, or on the subject side or the illumination light source A stereoscopic visual target comprising a black second visual target having the same shape as the first visual target, which is provided at a position close to the first visual target, is arranged.
[0005]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
First, the overall configuration of the apparatus will be described. FIG. 1 is a perspective view of an optical system when the apparatus of the embodiment is viewed from the right side, FIG. 2 is a perspective view of the optical system when the apparatus is viewed from the front, and the apparatus of the embodiment uses a concave mirror. Thus, it is a space-saving device that optically secures the inspection distance.
Reference numeral 1 denotes an eye to be examined, and 2 denotes a visual function testing device. A window 3 made of a glass plate provided with an antireflection film is disposed on the side of the visual function testing device 2 facing the eye 1 to be examined, and the eye 1 to be examined looks through the window 3. The window 3 may be provided with a filter instead of the glass plate. In addition, the inside of the visual function inspection device 2 is painted black so that the internal structure of the eye 1 is difficult to see.
Reference numeral 4 denotes a disk-shaped target disk plate made of a glass plate, and a large number of visual function test targets such as a stereoscopic target and a visual acuity target described later are formed on the same circumference by chromium vapor deposition or the like. ing. The optotype disc plate 4 is rotated by the optotype disc plate motor 6 to switch and arrange the optotypes to be presented to the subject. Reference numeral 7 denotes a mask plate for masking a part of the presented visual target, which is rotated by the mask plate motor 8 to put a necessary mask on the visual target.
[0006]
An illumination lamp 9 illuminates the target. 10 is a mirror, 11 is a beam splitter, and 12 is a concave mirror. The focal length of the concave mirror 12 of the apparatus of the embodiment is designed so that the optical distance between the visual target and the eye to be examined is 5 m. The light beam of the inspection target illuminated by the illumination lamp 9 is reflected upward by the mirror 10, passes through the beam splitter 11, and then is reflected by the concave mirror 12. The target luminous flux reflected by the concave mirror 12 is reflected by the beam splitter 11 and enters the eye to be examined.
The beam splitter 11 can change the inclination angle by the motor 13 and can adjust the optical path of the target luminous flux to the height of the eye to be examined.
Even if a convex lens is used instead of using a concave mirror as in the embodiment, a space-saving type apparatus in which the inspection distance is optically secured can be configured.
[0007]
FIG. 3 is a diagram for explaining a stereoscopic visual target formed and arranged on the visual target disc plate 4 (the figure shows a part of a section on the visual target disc plate 4 on which the stereoscopic visual target is arranged). The stereoscopic visual target 20 shown in the figure is a precision stereoscopic inspection that inspects a stereoscopic parallax 40 seconds (a lift of 2 cm from a distance of 2.5 m) corresponding to a trigonometer test used for two types of large-scale inspections of a driver's license. It is an example of a target structure.
The four black circles 21 at the four corners are drawn black by chromium vapor deposition on the surface of the target disc plate 4 (the eye side to be examined) with a circle of the same diameter. As shown in FIG. 4, the floating black circle 22 at the center of the upper stage includes a large disk portion 40a having a black circular plane having the same diameter as the black circle 21, a small disk portion 40b having a smaller diameter than the large disk portion 40a, and both disk portions. The small disc portion 40c side of the visual target member 40 including the supporting portion 40c to be supported is attached to the surface of the visual target disc plate 4 by adhesion. The height in the axial direction of the visual target member 40 used for the stereoscopic visual target 20 of the embodiment is 1.1 mm. The submerged black circle 23 at the center of the lower stage is obtained by adhering the same side of the large disc portion 40a of the target member 40 as the raised black circle 22 from the back side of the target disc plate 4 having a thickness of 1.6 mm. It is. In the stereoscopic visual target 20 of the embodiment, since the sinking black circle 23 has only to secure a black circular plane having the same diameter as the black circle 21, it may be formed on the back surface of the visual target disc plate 4 by chromium vapor deposition. Alternatively, a member having only the large disk portion 40a may be bonded.
[0008]
The reason why the stereoscopic vision 20 having such a configuration can realize a stereoscopic parallax of 40 seconds with respect to an inspection distance of 5 m will be described.
Now, assuming that the interpupillary distance of the subject is PD, the lift amount is dS, the examination distance is S, and the stereoscopic parallax dθ, there is the following relationship.
[Expression 1]
Here, if dθ = 40 seconds, PD = 60 mm, and S = 5000 mm, dS is about 80.8 mm. In other words, this means that the object surface at the front side 80.8 mm (the back side 80.8 mm) has an uplift amount (sink amount) of 3D parallax for 40 seconds with respect to the object surface actually separated by a distance of 5000 mm. Means.
In addition, when the focal length of the concave mirror 12 of the apparatus of the embodiment is f, the distance from the eye to the concave mirror 12 is L, and the distance from the surface of the target disc plate 4 to the concave mirror 12 is x, From the imaging formula,
[Expression 2]
The following relational expression holds. For example, if f = −500 mm, S = 5000 mm, and L = 1300 mm, x = about 440.4 mm is obtained.
[0009]
On the other hand, the distance from the visual target surface (the visual target surface of the floating black circle 22) to the concave mirror 12 for obtaining the lift amount of 80.8 mm obtained from Equation 1 is x ′, and these are expressed by Equation 2. If solved by fitting, x ′ = about 439.3 is obtained. The difference between x and x ', that is, the difference corresponding to the stereoscopic parallax of 40 seconds is about 1.1 mm.
Further, when considering the sinking amount with respect to the surface of the target disc plate 4, it is necessary to consider the refractive index due to the glass material. When 1.1 mm in the air is converted into a glass amount having a refractive index n = 1.52, it is about 1.6 mm. This corresponds exactly to the thickness of the target disc plate 4.
[0010]
From the above, as shown in FIG. 3, the surface of the eye side of the floating black circle 22 is set to a distance of 1.1 mm with respect to the black circle 21 on the surface of the target disc plate 4, thereby providing a stereoscopic parallax. A lifting amount of 40 seconds can be realized. On the other hand, the surface on the subject side of the sunken black circle 23 is attached to the target disc plate 4 which is a glass plate having a thickness of 1.6 mm, thereby providing a distance of 1.1 mm in terms of air and a stereoscopic parallax of 40 seconds. The amount of sinking can be realized.
Since the vertical magnification by the concave mirror (convex lens) is the square of the horizontal magnification, the stereoscopic target to be compared is preferably close to a plane as in the embodiment (configured so that the plane protrudes). . Each target surface is not limited to a circle, but may have another shape.
[0011]
The operation of the apparatus having the above configuration will be described with reference to the electric system block diagram of FIG. Here, a description will be given focusing on inspection using a stereoscopic target.
When the subject is positioned at a predetermined distance in front of the apparatus and a power switch (not shown) is turned on, the control circuit 50 turns on the illumination lamp 9 via the drive circuit 51 and illuminates the target on the target disc plate 4. To do. When an angle change switch arranged on the controller 52 is operated, the control circuit 50 drives the motor 13 via the drive circuit 53 to change the tilt angle of the beam splitter 11 so that the subject can illuminate the illumination lamp. The inspection target illuminated at 9 can be confirmed at the center of the beam splitter 11.
When the adjustment of the apparatus is completed, an inspection target is selected by pushing a target selection switch arranged on the controller 52, and an inspection is performed. The control circuit 50 rotationally drives the target disc plate motor 6 via the drive circuit 54, sets a target corresponding to the input switch on the optical path, and presents the target to the eye to be examined.
[0012]
When performing the stereoscopic inspection, the stereoscopic target selection switch of the controller 52 is pressed. A stereoscopic target 20 on the target disk plate 4 is set on the optical path, and the target luminous flux illuminated by the illumination lamp 9 is a mirror 10, a beam splitter 11, a concave mirror 12, and a window 3. Reaches the eye to be examined. At this time, the subject can observe the stereoscopic visual target 20 in the presentation state as shown in FIG. 6 in a natural state close to the daily visual environment of binocular release. For each black circle of the stereoscopic visual target that can be observed through the window 3, only a black circular plane can be seen, but if the difference between the raised black circle 22 and the sinking black circle 23 can be visually recognized with respect to the black circle 21, the eye to be examined is 40 seconds ( A stereoscopic parallax of 80 mm in terms of an inspection distance of 5 m can be confirmed.
[0013]
Further, the stereoscopic vision target 20 can be masked by the mask plate 7 so that only the upper part or only the lower part can be seen. As a mask to be applied to the visual target, a necessary mask is selected by a mask selection switch of the controller 52. The control circuit 50 rotates the mask plate motor 8 through the driving circuit to put a mask on the visual target. When the target is masked in this way, only the floating side of the upper stage or the sinking side of the lower stage is shown in comparison with the method of simultaneously showing, so that a more accurate inspection can be performed.
[0014]
The embodiments described above can be variously modified. FIG. 7 shows some modified examples.
(A) is an example in which a target is sinked on the back side of the target disc plate 4, and a transparent member 60 such as glass having an etching target on the light source side is joined to the rear surface of the target disc plate 4. To do. In this way, the thickness of the target itself (the black portion of the target) can be reduced, and by adjusting the thickness of the transparent member 60, a sinking amount of a slight distance from the target disc plate 4 can be secured. can do. (In this case, it is necessary to consider the coefficient of refractive index depending on the material of the transparent member).
The stereoscopic visual target shown in (b) is a joint arrangement by placing the visual targets 61a and 61c on the same plane and separating the visual target 61b by a distance corresponding to the stereoscopic parallax by thin plate-shaped visual targets 61a, 61b, and 61c. It is what.
The stereoscopic visual target shown in (c) is shown in FIG. 4 so that the floating heights from the black circle 62a drawn on the surface of the visual target disc plate 4 are 40 cm, 25 cm, and 12 cm with respect to the inspection distance of 5 m. Black circles 62b, 62c and 62d similar to the target member are joined to the target disc plate 4 while changing the distance in the optical axis direction. The joining method is the same as that of the example. If this stereoscopic vision target is also shown with the horizontal mask and the upper, middle, and lower three stages separately, the stereoscopic parallax of the subject can be confirmed more accurately.
[0015]
【The invention's effect】
As described above, according to the present invention, precise stereoscopic inspection can be realized with a simple configuration without using a polarizing plate. Therefore, it is possible to perform an inspection in a state close to the daily visual environment, and an accurate inspection result can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view of an optical system when an apparatus according to an embodiment is viewed from the right side.
FIG. 2 is a perspective view of the optical system when the apparatus of the embodiment is viewed from the front.
FIG. 3 is a diagram for explaining a stereoscopic visual target formed and arranged on the visual target disc plate 4;
FIG. 4 is a diagram for explaining the configuration of a floating black circle target arranged on the target disc plate 4;
FIG. 5 is a block diagram of an electric system of the apparatus according to the embodiment.
FIG. 6 is a diagram illustrating a presentation state when a subject views a stereoscopic target.
FIG. 7 is a diagram illustrating a modification example of a stereoscopic visual target.
[Explanation of symbols]
2 Visual function inspection device 4 Target disc plate 6 Target disc plate motor 7 Mask plate 12 Concave mirror
20 stereoscopic target 21 black circle 22 floating black circle 23 sinking black circle 40 target member

Claims (1)

A target for visual function inspection is placed on the target disc, and the target is switched from the target reflected by the concave mirror by means of rotating the disc to present the target target to the subject. And a space-saving optical system that reflects the light beam toward the subject's eye by mirror reflection, and the target disk has a transparent surface on the target disk surface with the transmission surface of the target disk as a background. The first target having a predetermined black shape and the optical distance corresponding to the expected amount of elevation or sinking of the stereoscopic parallax with respect to the first target are brought closer to the subject or the illumination light source. A visual function testing device, wherein a stereoscopic visual target comprising a black second visual target having the same shape as that of the first visual target is disposed at a predetermined position.

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