JPH0140481Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a visual acuity testing device that includes an optotype display device, a viewing window, and an optical path from the optotype display device to the viewing window.

(Prior art) Conventionally, when testing visual acuity, a subject is positioned 5 meters away from a visual acuity test chart (hereinafter referred to as an optotype) and the test subject is asked to read the figures and letters on the optotype. is common. In this case, a space of 5 m or more is required for the visual acuity test. 5
There are optotypes that can be inspected at a distance shorter than m, for example 3.5 meters, but strictly speaking, the accuracy of the inspection results in this case is slightly lower. because,
This is because a distance of 5 meters or more is required to prevent the human eye's ability to adjust.

Therefore, without requiring much inspection space, we
There is a lens that allows you to see a visual target at a distance of . That is, by using a concave lens or a concave mirror, a nearby visual target can be made to appear as if it is far away.
Such techniques are disclosed in, for example, Japanese Patent Laid-Open No. 58-89235 and Japanese Patent Laid-Open No. 59-62028.

(Problems to be solved by the invention) In the above-mentioned conventional technology, since a concave lens or a concave mirror is used, it is necessary to correctly set the subject's eye position to the focal point of the concave lens or concave mirror. be. That is, the subject's forehead or the like is fixed near the viewing window of the visual acuity testing device.
In this case, it becomes impossible to perform lens fitting operations that are often performed at eyeglass stores. In other words, it is not possible to carry out an operation in which an eye test frame is placed on the eye of the subject, and the examiner performs a visual acuity test while sequentially setting the test lenses on the eye test frame, and then selects a lens with a preferable strength. It disappears.

Furthermore, optometry using a concave lens or concave mirror is not necessarily equivalent to an actual optometry performed from a position 5 meters away, and is not suitable for exact visual acuity measurement.

The purpose of this invention is to provide a visual acuity testing device which is equivalent to actually examining the eye from a position far away from the visual target, and which is also very compact and does not take up much space.

(Means for Solving the Problems) In order to achieve the above object, the visual acuity testing device according to this invention includes an optotype display device, a viewing window, and an optical path from the optotype display device to the viewing window. In the inspection device, a half mirror provided in the middle of the optical path, a folding plane mirror provided in the middle of the optical path between the half mirror and the viewing window, and an optical path between the half mirror and the folding plane mirror. and a plurality of intermediate plane mirrors provided in the middle.
An optical path from the optotype display device to the viewing window includes a first optical path from the half mirror to the folding plane mirror via the plurality of intermediate plane mirrors, and a first optical path from the folding plane mirror to the plurality of intermediate plane mirrors. and a third optical path leading from the half mirror to the viewing window.
It has an optical path of

(Function) Since the first optical path from the half mirror to the folding plane mirror passes through a plurality of intermediate plane mirrors, by devising the arrangement of these intermediate plane mirrors, it is possible to create a long optical path with a very compact configuration. can be obtained. Furthermore, since the second optical path returning from the folding plane mirror to the half mirror follows the first optical path, twice the optical path length can be obtained by using the same intermediate plane mirror configuration. It turns out. As a result, it is possible to obtain a visual acuity testing device that has a very compact configuration and is completely equivalent to eye examination from a long distance from the optotype, without using a concave mirror or a concave lens.

(Embodiments) Hereinafter, embodiments of this invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view showing the internal structure of an embodiment of this invention. The light emitted from the halogen lamp 1 passes through the optotype set in the optotype switching device 2,
Further, it passes through the enlarging device 30, is reflected by the plane mirrors 3 and 4 for direction change, changes its direction by 180 degrees, and reaches the back surface 31 of the half mirror 5. The back surface 31 of the half mirror 5 has a frosted glass shape, and an enlarged image 32 of the optotype is formed on the back surface 31 of the half mirror 5. In this embodiment, a combination of a halogen lamp 1, an optotype switching device 2, plane mirrors 3 and 4, and a back surface 31 of a half mirror 5 constitutes an optotype display device. By using the plane mirrors 3 and 4, the arrangement from the halogen lamp 1 to the back surface 31 of the half mirror 5 is made compact.

Between the optical path from the half mirror 5 to the folding plane mirror 6, there are five intermediate plane mirrors 7, 8,
9, 10, and 11 are arranged. half mirror 5
and a folding plane mirror 6 and intermediate plane mirrors 7, 8, 9,
10 and 11 are arranged so as to form each side of a polygon. Back side 31 of half mirror 5
A portion of the light emitted from the upper image 32 passes through the half mirror surface 12, is reflected by the intermediate plane mirror 7, and is directed toward another intermediate plane mirror 8. In this way, the light is reflected one after another by the intermediate plane mirrors 8, 9, 10, and 11, and reaches the folding plane mirror 6. Folding plane mirror 6
The light reflected by the mirror returns to the half mirror 5 along the optical path that it has passed so far. A part of the light returning to the half mirror 5 is reflected by the half mirror surface 12 and goes toward the viewing window (see FIG. 2).

That is, this invention includes a first optical path 14 extending from the half mirror 5 to the folding plane mirror 6, and a second optical path returning from the folding plane mirror 6 to the half mirror 5.
There is an optical path 15, and a third optical path 16 from the half mirror 5 to the viewing window. In addition, in this idea,
The optical path from the optotype display device to the half mirror 5 may have any configuration. In the above embodiment, the back surface 31 of the half mirror 5 constitutes a part of the optotype display device, so the distance from the optotype display device to the half mirror surface 12 of the half mirror 5 is the same as the back surface 31 of the half mirror 5. 31 to the half mirror 12. In FIG. 1, for ease of understanding, the first optical path 14 is shown as a solid line, and the second optical path 14 is shown as a solid line.
The optical path 15 and the third optical path 16 are shown by broken lines.

In addition, the folding plane mirror 6 and the intermediate plane mirror 7,
8, 9, 10, and 11 are front mirrors. That is,
Light is reflected on the surfaces of these plane mirrors.

FIG. 2 is a perspective view showing the appearance of the visual acuity testing device according to this embodiment. The internal structure shown in FIG. 1 is housed in a box 17 with the right side in FIG. 1 facing down. The light 16 reflected by the half mirror surface 12 of the half mirror 5 passes through the viewing window 18 and reaches the eye 19 of the subject.

Eyes 19 of the subject from the back surface 31 of the half mirror 5
The length of the optical path leading to is set to 5 m. In this embodiment, the length of the optical path from the back surface 31 of the half mirror 5 to the viewing window 18 is 4 m, and the viewing window 18
The distance from the eye 19 to the subject's eye 19 is 1 m. The reason why the distance from the viewing window 18 to the subject's eyes 19 is set at 1 m is to facilitate the lens fitting operation at an eyeglass store or the like.

FIG. 3 is an enlarged sectional view showing details of the viewing window 18. Basically, the viewing window 18 only needs to be made by opening an opening 20 in the box 17. However, opening 20
It is preferable to cover the opening 20 with transparent glass to prevent dust and the like from entering the device. If the glass is simply covered with transparent glass, there is a risk that the subject's face or external light will be reflected on the glass. Therefore, in this embodiment, the transparent glass 21 is attached at an angle as shown in FIG. There is. Then, at the upper end of the viewing window 18, there is a canopy 2.
2 is formed. External light 23 reflected by the transparent glass 21 hits the eaves 22 and does not interfere with the visual acuity test. Note that the inside of the eaves 22 is painted black. The inside of the box 17 is also painted black to make it easier for the subject to see the optotype.

The viewing window 18 may be configured to be foldable to facilitate portability of the vision testing device.

An operation panel 24 is provided on the side of the box 17 shown in FIG.
is provided. This operation panel 24 is used for switching operation of the optotype switching device 2, and an enlarged view thereof is shown in FIG. This operation panel 24 includes
Twelve types of optotype patterns 25 are displayed. These optotype patterns 25 correspond to the optotypes set in the optotype switching device 2. A display lamp 26 is provided at the upper center of each optotype pattern 25, and is adapted to display which optotype is currently visible through the viewing window 18.
Below the optotype pattern there are two pushbutton switches 27, 28. When the examiner presses the pushbutton switch 27, the type of optotype pattern 25 changes to the next type clockwise in FIG. 4, and when the examiner presses the pushbutton switch 28, the type of the optotype pattern 25 changes counterclockwise. It's becoming like that. At this time, the lighting position of the display lamp 26 changes on the operation panel 24, while the optotype switching device 2 rotates clockwise or in the opposite direction to change the optotype.

The visual acuity test device shown in Figure 2 has a height of 70 cm and a width of 50 cm.
It is very small, measuring 15 cm and 15 cm in depth, and has an optical path length of 4 m from the optotype to the viewing window 18. Therefore, it is possible to install it in an eyeglass store with limited space or in a vehicle for selling eyeglasses outside. It is also convenient to carry.

In the above embodiment, the intermediate plane mirrors are arranged in a polygonal shape, but the invention is not limited to such an arrangement. For example, intermediate plane mirrors can be arranged on two parallel lines so that the optical path is zigzag.

(Effect of the invention) As explained above, this invention provides a plurality of intermediate plane mirrors in the middle of the optical path between the half mirror and the folding plane mirror to lengthen the optical path between the half mirror and the folding plane mirror. By using the optical path back and forth, a sufficient optical path length can be secured in a very narrow space. As a result, it is possible to perform an accurate visual acuity test without taking up much space.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the internal structure of an embodiment of this invention, FIG. 2 is a perspective view showing the external appearance of a visual acuity testing device according to this embodiment, and FIG. 3 is an enlarged sectional view of a viewing window. FIG. 4 is an enlarged view of the operation panel. 1...Halogen lamp, 2...Optotype switching device,
5...half mirror, 6...plane mirror for folding,
7, 8, 9, 10, 11... intermediate plane mirror, 14...
...first optical path, 15...second optical path, 16...third optical path, 18...peep window.

Claims (1)

[Claims for Utility Model Registration] A visual acuity test device comprising an optotype display device, a viewing window, and an optical path from the optotype display device to the viewing window, including a half mirror provided in the middle of the optical path, and the half mirror. and a folding plane mirror provided in the middle of the optical path between the half mirror and the folding plane mirror, and a plurality of intermediate plane mirrors provided in the middle of the optical path between the half mirror and the folding plane mirror. an optical path from the half mirror to the viewing window, a first optical path from the half mirror to the folding plane mirror via the plurality of intermediate plane mirrors, and a first optical path returning from the folding plane mirror to the half mirror via the plurality of intermediate plane mirrors. a third optical path from the half mirror to the viewing window;
A visual acuity testing device characterized by having an optical path.