WO2016072273A1 - Eyesight examination device - Google Patents

Abstract

When a corrective lens for diopter adjustment is attached in front of an eye under test, the focal position of an observation optical system for observing an eye and an image pickup magnification ratio undergo an unwanted change. In the present invention, the following are provided: a display element 12 for displaying a visual target for a testee; a display optical system 11 in which disposed, in the order given and on an optical axis 18 which extends from an eye position at which a testee'e eye 8 is located to the display element 12, are a first lens, a mirror 20 that has wavelength selectability, and a second lens group 21; an image pickup element 16 for picking up an image of the eye 8 of the testee which is located at the eye position; an observation optical system 15 that is disposed on an optical axis which extends from the eye position to the image pickup element; and a diopter adjustment mechanism for adjusting the diopter of the testee. The display optical system 11 and the observation optical system 15 share an optical axis 18a which extends from the eye position to the mirror 20. The second lens group 21 is disposed on an optical axis 18b which is not shared with the observation optical system 15. The diopter adjusting means adjusts diopter by causing the lenses belonging to the second lens group to move in the optical axis direction.

Description

Visual inspection device

The present invention relates to a visual inspection apparatus used when inspecting the visual function of an eye.

One of the eye tests is a visual test that tests the visual function of the eye. A visual inspection is a typical visual inspection. The visual field inspection is performed for diagnosis of visual field constriction, visual field defect, etc. caused by glaucoma or retinal detachment, for example.

Some conventional visual field inspection devices display (present) a visual target on a dome-shaped screen to inspect the visual field of a subject (see, for example, Patent Document 1). In this type of visual field inspection apparatus, when the subject's eyeball (hereinafter also referred to as “test eye”) is placed at the center of the dome, and the subject looks at the screen from there, for example, how much It is inspected whether the target can be seen up to the range of, or at which position the target is not visible.

At this time, if the eye to be examined is a myopic eye or a hyperopic eye, the image of the target displayed on the screen or the like is not focused on the retina of the eye to be examined, but is focused when it is deviated from it. For this reason, the target image recognized by the subject is blurred. Therefore, Patent Document 2 describes a perimeter equipped with a mechanism for moving a display element that displays a visual target. In this perimeter, the diopter is adjusted by moving a display element installed in front of the eye to be examined toward and away from the eye to be examined. However, in this perimeter, the mechanism for moving the display element becomes large.

On the other hand, Patent Document 3 describes a perimeter that enables a correction lens for diopter adjustment to be attached in front of the eye to be examined. In this perimeter, the diopter can be adjusted by inputting the diopter of the eye to be examined and attaching a correction lens suitable for the diopter.

JP 2012-20196 A Japanese Patent No. 4518077 JP 2003-164425 A

Among conventional visual inspection apparatuses, including the perimeter described in Patent Document 3, a display optical system for presenting a visual target to the subject and an observation optical system for observing the eyeball of the subject There is something with.
In this type of visual inspection apparatus, the subject's eyeball is imaged by the imaging element through the observation optical system. Therefore, when a correction lens is attached in front of the eye of the subject eye as described in Patent Document 3, The correcting lens constitutes a part of the observation optical system. For this reason, the influence on the observation optical system is inevitable. Specifically, in the observation optical system, for example, the focus position is shifted from the eyeball position, or the photographing magnification is changed.

The main object of the present invention is to provide a visual inspection apparatus capable of adjusting the diopter without affecting the observation optical system.

A first aspect of the present invention includes a display element for displaying a visual target on a subject,
A display optical system in which a first lens, a mirror having wavelength selectivity, and a second lens group are sequentially arranged on the optical axis from the eyeball position where the eyeball of the subject is arranged to the display element. When,
An imaging device for imaging the eyeball of the subject arranged at the eyeball position;
An observation optical system disposed on the optical axis from the eyeball position to the image sensor;
Diopter adjustment means for adjusting the diopter of the subject;
With
The display optical system and the observation optical system share an optical axis from the eyeball position to the mirror,
The second lens group is disposed on an optical axis not shared with the observation optical system,
The diopter adjustment means adjusts the diopter by moving a lens belonging to the second lens group in the optical axis direction.

According to a second aspect of the present invention, the diopter adjusting means adjusts the diopter by moving the lens closest to the display element among the lenses belonging to the second lens group. It is a visual inspection apparatus as described in 1 aspect.

The third aspect of the present invention is characterized in that the diopter adjusting means adjusts the diopter by moving a lens having a focal length of more than 10 mm and less than 50 mm among the lenses belonging to the second lens group. The visual inspection device according to the first or second aspect.

According to a fourth aspect of the present invention, the display optical system displays the display from the display optical system when the subject views the target through the display optical system from the eyeball position, at least within the range of visual inspection. The visual inspection apparatus according to any one of the first to third aspects, characterized in that all chief rays incident on the display surface of the element have telecentricity parallel to the optical axis. is there.

According to a fifth aspect of the present invention, a change in pupil position is detected based on an eyeball image picked up by the image pickup device, and a position of a visual target displayed on the display device is corrected according to the detection result. The visual inspection apparatus according to any one of the first to fourth aspects, further comprising a mark display position correcting unit.

According to the present invention, the diopter can be adjusted without affecting the observation optical system.

It is the schematic which shows the structural example of the visual inspection apparatus which concerns on embodiment of this invention. It is the schematic including the structure of the optical system and control system of the visual inspection apparatus which concerns on embodiment of this invention. It is a figure which shows the relationship between the display optical system and diopter adjustment mechanism in embodiment of this invention. It is a figure for demonstrating the characteristic of a display optical system. It is the schematic which shows the other structural example of a display optical system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the present embodiment, a case where the present invention is applied to a head-mounted visual inspection apparatus will be described as an example.
In the embodiment of the present invention, description will be given in the following order.
1. 1. Configuration of visual inspection device 2. Characteristics of display optical system Visual inspection method 4. 4. Effects of the embodiment Modifications etc.

<1. Configuration of visual inspection device>
FIG. 1 is a schematic diagram showing a configuration example of a visual inspection apparatus according to an embodiment of the present invention.
The illustrated visual inspection apparatus 1 is a head-mounted visual inspection apparatus that is used by being mounted on the head 3 of a subject 2. The visual inspection device 1 generally includes a device main body 5 and a mounting tool 6 mechanically connected to the device main body 5.

The apparatus body 5 includes a housing 7 having a space inside. The internal space of the housing 7 is divided into left and right. This is because the visual inspection is performed separately for the left eye 8L and the right eye 8R of the subject 2. In this visual inspection, when the left eye 8L is the eye to be examined, the subject 2 sees the target through the pupil 9L of the left eye 8L, and when the right eye 8R is the eye to be examined, the subject 2 sees the target through the pupil 9R of the right eye 8R.

The “target” described here is displayed in order to give light stimulation to the eyeball of the subject when examining the subject's vision. There are no particular restrictions on the size, shape, etc. of the visual target. For example, in the case of glaucoma examination, the point of light is displayed as a target with a predetermined size, and the position of the point of light is changed to examine the presence or absence of the missing visual field and the location of the defect (specific) can do.

In one space of the housing 7, a display optical system 11L and a display element 12L are provided. In the other internal space of the housing 7, a display optical system 11R and a display element 12R are provided. The display optical system 11L and the display element 12L are provided for visual inspection of the left eye 8L of the subject 2. The display optical system 11R and the display element 12R are provided for visual inspection of the right eye 8R of the subject 2.

The mounting tool 6 is for mounting and fixing the apparatus body 5 to the head 3 of the subject 2. The wearing tool 6 includes a belt 13 that is stretched in a U-shape from both sides of the subject 2 to the back of the head, and a belt 14 that is stretched over the top of the subject 2. Then, in a state where the length of the belt 14 is appropriately adjusted, the mechanism 13 can be mounted on the head 3 of the subject 2 by pulling and tightening the belt 13 from the back head side.

In the following description, when the left eye 8L and the right eye 8R of the subject 2 are described without distinction between left and right, the symbols L and R are omitted, and the eyeball 8 and the pupil 9 are collectively referred to. Similarly, when the display optical systems 11L and 11R and the display elements 12L and 12R are described without distinction for the left eye and the right eye, the reference optical systems 11 and 11 are omitted by omitting the symbols L and R, respectively. Collectively referred to as the display element 12.

FIG. 2 is a schematic diagram including configurations of an optical system and a control system of the visual inspection apparatus according to the embodiment of the present invention.
As shown in the figure, the visual inspection apparatus 1 includes an observation optical system 15 for observing the eyeball 8 of the subject and the test optical system 15 in addition to the display optical system 11 and the display element 12 described above. An imaging device 16 that images the eyeball 8 of the person, an infrared light source 17 that irradiates infrared rays to the eyeball 8 of the subject, a control unit 30, and a response switch 31. The observation optical system 15, the image sensor 16, and the infrared light source 17 are provided separately for the left eye and the right eye of the subject, respectively, similarly to the display optical system 11 and the display element 12 described above, and the control unit 30. One response switch 31 is provided for each visual inspection device 1.

The display optical system 11 is provided on the optical axis 18 between the eyeball position where the eyeball 8 of the subject is placed and the display surface 12 a of the display element 12. Specifically, the display optical system 11 has a configuration in which a first lens 19, a mirror 20, and a second lens group 21 are arranged in order from the eyeball position side of the subject. Hereinafter, each component will be described. In the following description, among the optical axes 18 from the eyeball position of the subject to the display element 12, the optical axis from the eyeball position to the mirror 20 is the optical axis 18a, and the optical axis from the mirror 20 to the display element 12 is the optical axis. Is the optical axis 18b.

The first lens 19 is disposed on the optical axis 18 a from the eyeball position to the mirror 20. The first lens 19 is configured using an aspherical lens (convex lens) having positive power. The first lens 19 converges the light reflected by the mirror 20 and incident on the first lens 19 onto the pupil 9 of the subject, while the light divergence occurs when the subject views an object through the pupil 9 at a wide angle. It is to suppress. In FIG. 2, when a point of light serving as a target is displayed on the display surface 12a of the display element 12, and the subject views the target through the display optical system 11 from the eyeball position, the center of the pupil of the subject is displayed. The incident angle of the chief ray incident on the first lens 19 from is represented by the symbol θ. The incident angle θ is an angle with respect to the optical axis 18a (an angle formed between the principal ray passing through the center of the pupil and the optical axis 18a). The outer diameter (diameter) and position of the first lens 19 on the optical axis 18a are set under conditions that can secure at least a viewing angle necessary for visual inspection. Specifically, the maximum viewing angle (maximum value of θ) of the display optical system 11 using the first lens 19 is preferably 30 degrees or more and 60 degrees or less at a half field angle (60 degrees or more at all angles). , 120 degrees or less).

The mirror 20 is disposed on the opposite side of the eyeball position on the optical axis 18a from the eyeball position to the mirror 20 with the first lens 19 interposed therebetween. The mirror 20 is configured using a mirror having wavelength selectivity. Specifically, the mirror 20 is configured using a cold mirror that reflects visible light and transmits infrared rays. The inclination of the reflecting surface of the mirror 20 with respect to the optical axis 18a is such that the angle α formed by the optical axis 18a and the optical axis 18b bent by the mirror 20 is preferably less than 90 degrees, more preferably less than 80 degrees, and still more preferably. It is set to be in the range of “40 degrees <α <70 degrees”.

Here, when α ≦ 40 °, the display element 12 and the second lens group 21 are too close to the head of the subject, and they may interfere with the head. On the other hand, when α> 40 °, it is possible to avoid the display element 12 and the second lens group 21 from interfering with the head. On the other hand, when α ≧ 90 °, the visual inspection device 1 is likely to slip off the head when the subject tilts the head forward. On the other hand, when α <90 °, the visual inspection device 1 is less likely to slip off the head when the subject tilts the head forward.

The second lens group 21 is disposed on the optical axis 18b from the mirror 20 to the display element 12. The second lens group 21 is configured by using three lenses 21a, 21b, and 21c. The three lenses 21a, 21b, and 21c are sequentially arranged from the mirror 20 side toward the display element 12 side. That is, the lens 21a is disposed at a position closest to the mirror 20 on the optical axis 18b, and the lens 21c is disposed at a position closest to the display element 12 on the optical axis 18b. A lens 21b is disposed between the two lenses 21a and 21c. The lens 21b is arranged near the lens 21c in a state of being separated from the lens 21a.

The lens 21a is configured using an aspherical lens (convex lens) having positive power. The lens 21b is configured by using an aspheric lens (concave lens) having negative power, and the lens 21c is configured by using an aspheric lens (convex meniscus lens) having positive power. The outer diameter (diameter) of the lens 21a is larger than the outer diameters of the other lenses 21b and 21c, and the outer diameters of the lenses 21b and 21c are substantially equal to each other.

Here, when the Abbe number of the material constituting the first lens 19 is v1, the first lens 19 is made of a material (glass, plastic, etc.) that satisfies the relational expression “45 <v1 <80”. . On the other hand, when the Abbe numbers of the lenses 21a and 21c having positive power among the lenses 21a to 21c constituting the second lens group 21 are both v2, each of the lenses 21a and 21c is “45 <v2 <80”. It is comprised with the material which satisfy | fills the relational expression. When the Abbe number of the lens 21b having negative power is v3, the lens 21b is made of a material that satisfies the relational expression “15 <v3 <30”.
Further, when the focal length of the first lens 19 is f1, and the focal length of the second lens group 21 is f2, these satisfy the relationship of “0 <f1 / f2 <1.0”. Further, the focal length f1 of the first lens 19 is the sum (a + b) of the optical distance a from the first lens 19 to the mirror 20 and the optical distance b from the mirror 20 to the second lens group 21 (lens 21a). ) And shorter than that.

The display element 12 is disposed on the optical axis 18b from the mirror 20 to the display element 12 so as to face the lens 21c of the second lens group 21. The display element 12 is configured using, for example, a flat display element such as a liquid crystal display element having a backlight. The display surface 12a of the display element 12 has a configuration in which a large number of pixels are arranged in a matrix. When an image (including a visual target) is actually displayed on the display surface 12a, display and non-display (on / off) of the image can be controlled in units of pixels. The display surface 12a of the display element 12 preferably has a display size with a diagonal length of 1.5 inches or less, more preferably a display size with a diagonal length of 1 inch or less. The optical axis 18b is aligned at the center.

In the display optical system 11 and the display element 12 having the above-described configuration, when the visual target is displayed on the display surface 12a of the display element 12, the subject 2 moves the first lens 19, the mirror 20, and the second lens from the eyeball position. The target is viewed through the group 21. In that case, if the outer diameter of the first lens 19 closest to the eyeball position is increased, visual inspection can be performed in a wider range. However, when the outer diameter of the first lens 19 is increased, the principal ray passing through the lens end is largely inclined with respect to the optical axis 18 (18a). Therefore, when the power of the first lens 19 is low, the chief ray passing through the lens end is diverged.

Therefore, in the present embodiment, by using a lens with high power (preferably, power is 20D (dioptre) or more and 60D or less) for the first lens 19, the principal ray passing through the lens end of the first lens 19 is increased. The light is refracted and stored on the reflection surface of the mirror 20. However, when the high-power first lens 19 is used in this way, the main light beam is condensed and focused in the middle of the optical path from the first lens 19 to the second lens group 21. For this reason, the second lens group 21 is disposed on the optical axis 18b in order to condense (image) the principal ray bundle focused in the middle of the optical path on the display surface 12a of the display element 12 again. Yes. In order to correct chromatic aberration and image magnification, the second lens group 21 is composed of three lenses 21a, 21b, and 21c.

The observation optical system 15 is for observing, for example, the anterior part of the eye including the pupil 9, the iris, the sclera, or the fundus of the eye including the retina 10 with the eyeball 8 of the subject as an observation target. The observation optical system 15 is provided on the optical axis 18 from the eyeball position of the subject to the image sensor 16. Specifically, the observation optical system 15 has a configuration in which a first lens 19, a mirror 20, and a third lens 22 are arranged in order from the eyeball position side of the subject. Among these, the first lens 19 and the mirror 20 are common (shared) with the display optical system 11 described above, including the optical axis 18a. If the optical axis from the mirror 20 to the image sensor 16 is the optical axis 18c, the optical axis 18c is substantially parallel to the optical axis 18a described above.

The third lens 22 is disposed on the optical axis 18 c from the mirror 20 to the image sensor 16. The third lens 22 is configured using an aspherical lens (convex lens) having positive power. When observing the eyeball 8 using the first lens 19 as an objective lens, the third lens 22 transmits light that enters the first lens 19 from the eyeball 8 and passes through the mirror 20 to the imaging surface 16 a of the imaging device 16. The image is formed.

The imaging element 16 images an eyeball (anterior eye part, fundus oculi part, etc.) 8 to be examined. The image sensor 16 is configured using a CCD (Charge Coupled Device) image sensor having sensitivity to infrared rays, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or the like. The image pickup surface 16a of the image pickup device 16 is disposed on the optical axis 18c so as to face the eyeball 8, and the optical axis 18c is aligned with the center of the image pickup surface 16a.

The infrared light source 17 irradiates infrared rays toward the eyeball position of the subject. The infrared light source 17 is configured using a pair of infrared light emitting diodes 17a and 17b. The pair of infrared light emitting diodes 17a and 17b are arranged in an obliquely upward and obliquely downward direction with respect to the eyeball position of the subject so as not to disturb the visual field of the subject. One infrared light-emitting diode 17a irradiates the subject's eyeball 8 with infrared rays obliquely from above, and the other infrared light-emitting diode 17b irradiates the subject's eyeball 8 with infrared rays obliquely from below. It is configured to do.

In the observation optical system 15 and the image sensor 16 having the above-described configuration, the eyeball 8 is irradiated via the first lens 19, the mirror 20, and the third lens 22 while irradiating the eyeball 8 of the subject with infrared rays from the infrared light source 17. The image is picked up by the image pickup device 16. In addition, the visual inspection device 1 according to the present embodiment detects (tracks) a change in the pupil position accompanying the rotational movement of the eyeball 8 based on the image of the eyeball 8 thus imaged, and according to the detection result, A target display position correcting means (also called a tracking function) for correcting the position of the target displayed on the display element 12 is provided. The visual target display position correcting means is one of the functions realized by the control unit 30 described later. The target display position correcting means is configured so that the light from the target displayed on the display element 12 is focused on the same measurement point on the retina 10 even when the eyeball 8 that should be in a fixation state slightly rotates. This corrects the display position of the target.

The control unit 30 realizes various functions (means) for visual inspection. The control unit 30 has, for example, a housing structure smaller than the apparatus main body 5 and is mounted on the rear head side of the mounting tool 6 and arranged. Thereby, the weight balance before and behind the apparatus main body 5 and the control part 30 can be maintained.

The control unit 30 is configured by a computer including a combination of CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), various interfaces, and the like. And the control part 30 is comprised so that various functions may be implement | achieved, when CPU runs the predetermined program stored in ROM or HDD. The control unit 30 has a function of controlling the operation of each unit such as the display element 12, the imaging element 16, and the infrared light source 17 incorporated in the apparatus main body 5 as an example of a function (means) realized by executing the program. . The predetermined program for realizing each function is used by being installed in a computer, but may be provided by being stored in a computer-readable storage medium prior to the installation, or the computer It may be provided through a communication line connected to.

The response switch 31 is a switch operated by the subject. When the subject presses down the response switch 31, an ON signal is output from the response switch 31 at that moment. This ON signal is taken into the control unit 30. The response switch 31 is a manual type that the subject holds and operates. However, the present invention is not limited to this, and a stepping switch may be used.

In addition to the above configuration, the visual inspection apparatus 1 according to the present embodiment includes a diopter adjustment mechanism 32 as an example of diopter adjustment means, as shown in FIG. The diopter adjustment mechanism 32 adjusts the appearance of the visual target in accordance with the visual acuity of the eyeball 8 of the subject 2. More specifically, when the eye to be examined is a myopic eye or a hyperopic eye, the image of the optotype displayed on the display element 12 is not formed on the retina 10 of the eyeball 8 and is blurred. A diopter adjustment mechanism 32 is a mechanism that adjusts the lens so that it can be clearly seen.

The diopter adjustment mechanism 32 adjusts the diopter by moving at least one of the lenses (21a to 21c) belonging to the second lens group 21 in the direction of the optical axis 18b. The second lens group 21 is disposed on the optical axis 18 b that is not shared with the observation optical system 15 among the optical axes 18 a and 18 b belonging to the display optical system 11. Therefore, any of the lenses 21a to 21c belonging to the second lens group 21 is moved, and the observation optical system 15 is not optically affected.

In moving the lenses 21a to 21c belonging to the second lens group 21 in the direction of the optical axis 18b, all of the lenses 21a to 21c may be moved, or only a part of the lenses may be moved. However, when the diopter is adjusted by moving a plurality of lenses, it is necessary to precisely control the moving amount and positional relationship of each lens. For this reason, there is a concern that the diopter adjustment mechanism 32 as a whole becomes complicated or large.

Therefore, in the present embodiment, a configuration is adopted in which only one of the lenses 21a to 21c belonging to the second lens group 21 is moved, preferably only the lens 21c closest to the optical axis 18b is moved. ing. Various mechanisms for moving the lens 21c are conceivable. For example, although not shown, a lens holder that holds the lens 21c is mounted on the movable portion of the linear guide, and the lens 21c is guided by the linear guide using a power transmission mechanism such as a ball screw mechanism or a gear mechanism. A mechanism for moving in the direction of the optical axis 18b may be employed.

The diopter adjustment mechanism 32 has a rotary adjustment dial (not shown), for example. This adjustment dial is rotated by the subject 2 who adjusts the diopter. When the subject 2 actually rotates the adjustment dial in one direction or the other, the lens 21c moves to one or the other in the optical axis direction according to the rotation direction and the rotation amount at that time.

The focal length of the lens 21c is preferably more than 10 mm and less than 50 mm, more preferably more than 15 mm and less than 40 mm, still more preferably more than 18 mm and less than 30 mm. Thus, when the lens 21c with a short focal length is used as a lens for diopter adjustment, the diopter changes greatly only by moving the lens 21c slightly in the optical axis direction. For this reason, the diopter adjustment amount is relatively large with respect to the movement amount of the lens 21c. In this case, although it is feared that it is difficult to finely adjust the diopter, the present inventor has adopted a configuration in which the lens 21c having a short focal length is intentionally moved. The reason will be described later.
Incidentally, when the focal length of the lens 21c is 10 mm or less, the diopter adjustment sensitivity increases too much, so the diopter changes greatly due to some adjustment error or position error, and the image observed by the subject is reduced. It becomes difficult to set the distance optimally. In addition, when the focal length of the lens 21c is 50 mm or more, the amount of movement due to diopter adjustment becomes large, and the magnification of the optical system changes greatly, so that it is observed by the subject of the target displayed on the display element. The angle that varies depends on the diopter.

<2. Characteristics of display optical system>
FIG. 4 is a diagram for explaining the characteristics of the display optical system.
In FIG. 4, the pupil 9 of the eyeball 8 is used as the exit pupil, and the chief ray passes through the center of the exit pupil (center of the pupil), while the luminous flux of the chief ray is focused on the display surface 12a of the display element 12. It is assumed that the subject 2 views the display surface 12a using the display surface 12a as the image formation surface of the light beam of each principal ray. In addition, the first lens 19, the mirror 20, and the second lens group 21 constituting the display optical system 11 are replaced with one virtual lens 11v for display. The focal length of the lens 11v is f, the incident angle of the principal ray with respect to the lens 11v is θ, and the image height on the display surface 12a is Y. In this case, the incident angle θ corresponds to the incident angle θ shown in FIG. 2, and the focal length f of the lens 11v corresponds to the focal length of the entire lens including the first lens 19 and the second lens group 21.

The display optical system 11 according to the present embodiment is the display optical system 11 when the subject views the visual target from the eyeball position through the display optical system 11 as shown in FIG. All the chief rays incident on the display surface 12a of the display element 12 have telecentricity that is parallel to the optical axis 18b. Thus, when the subject views the target displayed on the display surface 12a of the display element 12 through the lens 11v, for example, the display position of the target is “when the display surface 12a is at the center (on the optical axis)”. ”,“ When it is at one end of the display surface 12 a ”, and“ when it is at the other end of the display surface 12 a ”, the principal ray incident on the display surface 12 a from the lens 11 v (lens 21 c) is the optical axis 18. Parallel to (18b). “Parallel” described here means ideally the case where the angle formed between the principal ray incident on the display surface 12a and the optical axis 18b is 0 degree. In this specification, the angle is The case of 10 degrees or less, more preferably 5 degrees or less is also included in the concept of “parallel”.

In the present embodiment, each of the lenses 21a, 21b, and 21c of the first lens 19 and the second lens group 21 is an aspheric lens having a predetermined refractive index, and the display optical system is obtained by combining these lenses. 11 as a whole achieves telecentricity. However, in order for the display optical system 11 to have such optical characteristics, it is not necessary that all lenses constituting the display optical system 11 be aspherical lenses, for example, a combination of a plurality of spherical lenses or a spherical surface It can also be realized by a combination of a lens and an aspheric lens. In that case, it is preferable that at least the lens closest to the eyeball position (in the present embodiment, the first lens 19) among the plurality of lenses constituting the display optical system 11 is formed of an aspheric lens. The reason is that when the lens closest to the eyeball position is configured by an aspherical lens, the number of lenses can be reduced by increasing the degree of freedom in optical design compared to the case where it is configured by a spherical lens. This is because the size and weight of 1 can be reduced. In particular, an increase in the optical path from the eyeball position to the mirror 20 corresponds to an increase in the length of the apparatus main body 5 in front of the subject, resulting in a problem that it is difficult to ensure a weight balance. For this reason, it is preferable that the lens closest to the eyeball position is an aspherical lens and the forward projection amount is as small as possible.

<3. Visual inspection method>
If the visual inspection apparatus 1 having the above configuration is used, dynamic quantitative visual field inspection (Goldman visual field inspection), static quantitative visual field inspection, fundus visual field inspection (microperimetry), electroretinography (ERG) and others It is possible to perform the inspection. Here, the case where a static quantitative visual field inspection is performed is described as an example.

Static quantitative visual field inspection is performed as follows. First, a target is presented at one point in the field of view, and its brightness is gradually increased. Then, when the target has a certain brightness, the target can be seen from the subject. Therefore, the value corresponding to the brightness when the subject can see the target is set as the retina sensitivity at the point where the target is presented at that time. Then, the same measurement is performed for each point in the field of view, thereby quantitatively examining the difference in retinal sensitivity in the field of view and creating a map. There are a subjective examination and an objective examination in the static quantitative visual field examination. If the visual inspection apparatus 1 of the present embodiment is used, any type of inspection can be performed. This will be described below.

Self-aware inspection is performed as follows. First, the head-mounted visual inspection apparatus 1 is attached to the subject's head. Further, the response switch 31 is held in the hand of the subject. Next, based on a command from the control unit 30, a visual field inspection target is displayed at one point on the display surface 12 a of the display element 12. At this time, the brightness of the target is initially darkened, and then the brightness of the target is gradually increased. Then, even if it is dark at first and the target is not visible to the subject, when the target reaches a certain brightness, the subject's retina responds to the light stimulus so that the subject can see the target. become. For this reason, when the target can be seen from the subject, the subject presses the response switch 31. When the subject presses the response switch 31, an ON signal is sent to the control unit 30. Upon receiving this ON signal, the control unit 30 performs a predetermined process, and sets the value corresponding to the brightness of the point of the target at that time as the sensitivity of the retina of that point. Thereafter, the same measurement is performed for each point in the field of view, thereby quantitatively examining the difference in retinal sensitivity in the field of view and creating a sensitivity map of the retina.

The objective test is performed as follows. First, the head-mounted visual inspection apparatus 1 is attached to the subject's head. In this case, it is not necessary for the subject to have the response switch 31. Next, based on a command from the control unit 30, a visual field inspection target is displayed at one point on the display surface 12 a of the display element 12. At this time, the brightness of the target is initially darkened, and then the brightness of the target is gradually increased. Then, even if it is dark at first and the target is not visible to the subject, when the target reaches a certain brightness, the subject's retina responds to the light stimulus so that the subject can see the target. become.

At that time, the size of the pupil 9 (pupil diameter) of the subject changes according to the brightness of the target. Specifically, the diameter of the pupil 9 of the subject is reduced. The state change of the eyeball 8 at this time is imaged. The imaging of the eyeball 8 is performed by irradiating infrared rays from the infrared light source 17 toward the eyeball 8, and the image light of the eyeball 8 obtained thereby is transmitted to the imaging element 16 via the observation optical system 15 (19, 20, 22). This is performed by forming an image on the imaging surface 16a. The timing for starting imaging of the eyeball 8 may be set, for example, before the display of the visual target on the display surface 12a or simultaneously with the display of the visual target. Incidentally, since the human retina has no sensitivity to infrared rays, it does not affect the state change of the eyeball 8.

The image data of the eyeball 8 imaged using the image sensor 16 is taken into the control unit 30. Image data sent from the imaging device 16 indicates whether the pupil diameter of the subject has changed (reduced) in response to the brightness of the target in the process of gradually increasing the brightness of the target. Judgment based on. When it is determined that the pupil diameter of the subject has changed, the value corresponding to the brightness of the point of the target at that time is set as the sensitivity on the retina at that point. Thereafter, the same measurement is automatically performed one after another for each point in the field of view to quantitatively check the difference in sensitivity on the retina in the field of view, and a sensitivity map on the retina is automatically created.

The objective test uses a single upper threshold stimulation method in which a bright target is displayed on one point of the display surface 12a of the flat display element 12 and a sensitivity map is created by observing the degree of reduction of the pupil diameter. May be.

When such a visual inspection is performed, the subject 2 adjusts the diopter using the diopter adjustment mechanism 32 as necessary. Diopter adjustment is performed for each eye. At that time, the control unit 30 displays an image stored in the ROM or the like on the display element 12 for diopter adjustment. At this time, the image displayed on the display element 12 is not particularly limited, but an image having a shape and size that is easy to understand visually (for example, a Landolt ring, a hiragana, and the like) when viewed from the subject 2. Katakana, Romaji, etc.) are good.

Also, the measurer may determine the diopter with reference to the diopter measured by the optometry apparatus or the like.

Here, the initial position of the lens 21c of the second lens group 21 is that light rays from an image displayed on the display element 12 when the eyeball 8 of the subject 2 is a normal eye that is neither a myopic eye nor a hyperopic eye, The focus is set at the retina 10 of the eyeball 8. For this reason, when the eyeball 8 of the subject 2 is a myopic eye or a farsighted eye, the light beam from the image displayed on the display element 12 is not focused on the retina 10 of the eyeball 8, and the image is obtained from the subject 2. The image looks blurry. In this case, the subject 2 moves the lens 21c in the direction of the optical axis 18b by rotating the adjustment dial. Specifically, when the eyeball 8 of the subject 2 is a myopic eye, the lens 21c is moved closer to the display element 12 than the initial position by rotating the adjustment dial. When the eyeball 8 of the subject 2 is a hyperopic eye, the lens 21c is moved away from the display element 12 from the initial position by rotating the adjustment dial. Thereby, even if the eyeball 8 of the subject 2 is a myopic eye or a farsighted eye, the light beam from the image displayed on the display element 12 is focused on the retina 10 of the eyeball 8. Therefore, the image is clearly visible on the eyeball 8 of the subject 2.

<4. Effects of the embodiment>
According to the visual inspection device 1 according to the embodiment of the present invention, at least one of the effects described below can be obtained.

In the visual inspection apparatus 1 according to the present embodiment, the second lens group 21 is disposed on the optical axis 18b that is not shared with the observation optical system 15 among the optical axes 18a and 18b of the display optical system 11, and this second lens group 21 is disposed. A configuration is adopted in which the diopter is adjusted by moving the lens 21c belonging to the lens group 21. For this reason, the diopter can be adjusted without affecting the observation optical system 15.

Further, when the above-described target display position correcting means is provided, the following effects can be obtained.
That is, if a correction lens for diopter adjustment is inserted between the eyeball position and the first lens 19, the focal position of the observation optical system 15 changes. For this reason, a clear image cannot be obtained when the eyeball 8 is imaged by the image sensor 16 through the observation optical system 15. In addition, since the photographing magnification changes when the correction lens is inserted, the correspondence between the displacement amount of the pupil 9 calculated from the image of the eyeball 8 and the correction amount of the display position of the target is broken. For this reason, the correction amount (hereinafter referred to as “tracking correction amount”) for correcting the display position of the visual target deviates from an appropriate range, and stable visual inspection cannot be performed.
On the other hand, in this embodiment, since the diopter is adjusted not by inserting a correction lens but by moving the lens 21c, the tracking correction amount is less likely to shift. Accordingly, it is possible to stably perform visual inspection while suppressing the shift of the tracking correction amount within an appropriate range.

In the visual inspection device 1, it is effective to reduce the moving amount of the lens 21c as much as possible when adjusting the diopter. The reason is as follows.
That is, in the visual inspection apparatus 1, when confirming to what extent the angle θ (see FIG. 2) the eyeball 8 of the subject 2 can see the visual target, the angle based on the optical axis 18a A correspondence relationship between θ and the display position of the target with respect to the optical axis 18b is defined in advance. For example, when the target is presented at θ = 30 ° with respect to the eyeball 8 of the subject 2, the position set on the display surface 12 a of the display element 12 in association with θ = 30 °. The target is displayed on the screen. In that case, if the diopter adjustment mechanism 32 moves the lens 21c in the direction of the optical axis 18b, the position and angle of the principal ray incident on the lens 21c change before and after the movement, so the position of the image plane changes. End up. Then, since the correspondence between the angle θ and the display position of the target is broken, the target that is supposed to be originally displayed at θ = 30 ° is displayed at a position deviated from the target. Lack of accuracy. Therefore, in order to maintain the correspondence between the angle θ and the display position of the target with high accuracy, it is effective to reduce the moving amount of the lens 21c as much as possible.

In this regard, the visual inspection device 1 according to the present embodiment employs a configuration in which only the lens 21c closest to the display element 12 among the three lenses 21a to 21c belonging to the second lens group 21 is moved. In this configuration, the amount of movement of the lens 21c itself is directly related to the change in diopter, so that it is necessary for diopter adjustment compared to the case where the other lenses 21a and 21b belonging to the second lens group 21 are moved. The amount of lens movement is relatively small. Therefore, an error in the display position of the target can be suppressed to a small value. In particular, when the display optical system 11 has the telecentricity described above, each principal ray is parallel to the optical axis 18b between the lens 21c and the display element 12, and therefore the lens 21c is directed in the direction of the optical axis 18b. Even if moved, the position of the chief ray hardly changes. Therefore, the error in the display position of the target can be further reduced.

Also, in the visual inspection device 1 according to the present embodiment, among the lenses belonging to the second lens group 21, a configuration is adopted in which a lens 21c having a focal length of more than 10 mm and less than 50 mm is moved. For this reason, the diopter can be greatly changed by moving the lens 21c slightly in the direction of the optical axis 18b. Therefore, the amount of movement of the lens 21c for diopter adjustment can be reduced. As a result, the correspondence between the angle θ and the display position of the visual target can be maintained with high accuracy.

<5. Modified example>
The technical scope of the present invention is not limited to the above-described embodiments, and includes various modifications and improvements as long as the specific effects obtained by the constituent elements of the invention and combinations thereof can be derived.

For example, in the above embodiment, the mounting tool 6 of the visual inspection device 1 is configured using the belts 13 and 14, but if the device main body 5 can be mounted on the head 3 of the subject 2, You may employ | adopt the mounting tool 6 of what kind of structure. However, if the position of the apparatus body 5 moves during the visual inspection, a correct inspection result cannot be obtained. For this reason, as a structure of the mounting tool 6, it is preferable that it is a structure which can fix the apparatus main body 5 to the head 3 of the subject 2 properly.

In the above embodiment, the case where the present invention is applied to a head-mounted visual inspection apparatus has been described. However, the present invention is not limited to this, and may be applied to a visual inspection apparatus other than the head-mounted type. .

In the above embodiment, the display element 12 is configured using a liquid crystal display element. However, the present invention is not limited to this, and an organic EL (Electro Luminescence) display element may be used.

In the above embodiment, the display optical system 11 is configured with a total of four lenses, and the observation optical system 15 is configured with a total of two lenses (one of which is shared with the display optical system 11). The number and shape of the lenses constituting each optical system can be changed as necessary. However, the second lens group 21 is preferably composed of a plurality of lenses in order to correct chromatic aberration and image magnification by combining a lens having a positive power and a lens having a negative power. Further, the mirror 20 may be constituted by a dichroic mirror.

As an example, another configuration example of the display optical system is shown in FIG.
In FIG. 5, the second lens group 21 of the display optical system 11 is configured by using a total of four lenses 21a to 21d by adding a lens (convex lens) 21d, and the size of the display surface 12a of the flat display element 12. This is different from the above embodiment in that the height is reduced. When this configuration is adopted, the visual target can be displayed more clearly to the subject. Also in this configuration, it is possible to adjust the diopter according to the visual acuity of the subject by making the lens 21c movable in the optical axis direction.

DESCRIPTION OF SYMBOLS 1 ... Visual test | inspection apparatus 2 ... Subject 3 ... Head 5 ... Apparatus main body 6 ... Wearing tool 7 ... Housing 8 ... Eyeball 9 ... Pupil 11 ... Display optical system 12 ... Display element 12a ... Display surface 15 ... Observation optical system 16 ... Image sensor 17 ... Infrared light source 18 ... Optical axis (18a, 18b, 18c)
DESCRIPTION OF SYMBOLS 19 ... 1st lens 20 ... Mirror 21 ... 2nd lens group 21c ... Lens 22 ... 3rd lens 32 ... Diopter adjustment mechanism

Claims (5)

1. A display element for displaying an optotype on the subject;
   A display optical system in which a first lens, a mirror having wavelength selectivity, and a second lens group are sequentially arranged on the optical axis from the eyeball position where the eyeball of the subject is arranged to the display element. When,
   An imaging device for imaging the eyeball of the subject arranged at the eyeball position;
   An observation optical system disposed on the optical axis from the eyeball position to the image sensor;
   Diopter adjustment means for adjusting the diopter of the subject;
   With
   The display optical system and the observation optical system share an optical axis from the eyeball position to the mirror,
   The second lens group is disposed on an optical axis not shared with the observation optical system,
   The diopter adjusting means adjusts the diopter by moving a lens belonging to the second lens group in an optical axis direction.
2. The visual inspection apparatus according to claim 1, wherein the diopter adjusting unit adjusts the diopter by moving a lens closest to the display element among the lenses belonging to the second lens group.
3. 3. The diopter adjusting unit according to claim 1, wherein the diopter adjusting unit adjusts the diopter by moving a lens having a focal length of more than 10 mm and less than 50 mm among the lenses belonging to the second lens group. Visual inspection device.
4. The display optical system is, at least in the range of visual inspection, all incident from the display optical system to the display surface of the display element when the subject views the target from the eyeball position through the display optical system. The visual inspection apparatus according to any one of claims 1 to 3, wherein said principal ray has telecentricity parallel to said optical axis.
5. A target display position correcting unit that detects a change in pupil position based on an eyeball image captured by the image sensor and corrects the position of the target displayed on the display element according to the detection result; The visual inspection apparatus according to any one of claims 1 to 4, wherein:
   

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