JP2016198387A - Visual inspection device, target correction method for visual inspection device, and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head-mount type visual inspection device, target correction method for the visual inspection device, and display device, which are capable of accurately performing a visual field inspection even when an eyeball has rotated.SOLUTION: A visual inspection device, which is a head-mount type visual inspection device to be mounted on a subject's head, includes: display means for presenting a target to the subject's eyeball; photographing means for photographing the eyeball; rotation detection means for detecting the eyeball's rotation accompanying the subject's head's inclination in longitudinal directions, on the basis of the eyeball's image photographed by the photographing means; and target correction means for correcting a presentation position of the target presented by the display means, depending on the eyeball's rotation.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a visual inspection device, a target correction method for a visual inspection device, and a display device.

  In recent years, a head-mounted display device has been developed for a user to attach to his / her head and watch an image or the like. Furthermore, a head-mounted visual inspection device for performing visual field inspection for diagnosing symptoms such as visual field constriction such as glaucoma by applying a head-mounted display device has been proposed (for example, Patent Document 1). . In visual field inspection, when the visual target is presented on the display means of the visual inspection device, the subject answers whether the visual target is visible or detects the miosis of the pupil when the visual target is presented Thus, the visual field of the subject is measured.

JP-A-7-67833

  By the way, in the visual field inspection as described above, the subject may tilt his / her head to the left and right (with the direction from the nose to the back of the head as an axis) due to fatigue caused by concentrating on the visual field inspection. When the subject's head tilts to the left or right, the phenomenon that the eyeball rotates in the direction opposite to the tilt direction of the head, the so-called counter-rotating movement of the eyeball (OCR: Ocular Counterrolling, hereinafter simply referred to as “rotation”) It can happen. The present inventors have found that in such a head-mounted visual inspection apparatus, when such eyeball rotation occurs, the visual field inspection may not be performed accurately as follows.

  When the subject's head tilts to the left or right, the display element that presents the target is tilted with the head (follows the tilt of the head) because it is mounted on the head as a head-mounted type. Is in a state. The presentation position of the visual target when the subject's head is tilted is the same as the presentation position of the visual target before the subject's head is tilted. On the other hand, at this time, the eyeball of the subject rotates in the direction opposite to the tilt direction of the head. The presentation position of the visual target with respect to the eyeball at the time of rotation is relatively shifted in the direction opposite to the rotational direction of the eyeball from the presentation position of the visual target with respect to the eyeball before the rotation. Thus, in the state where the presentation position of the visual target has shifted, it becomes impossible to perform an accurate inspection on the target presentation position on the retina.

  Accordingly, the main object of the present invention is to provide a head-mounted visual inspection device, a visual target correction method for a visual inspection device, and a display device that accurately perform visual field inspection even when the eyeball is rotated. To do.

The first aspect of the present invention is:
A head-mounted visual inspection device mounted on a subject's head,
Display means for presenting a visual target to the eyeball of the subject;
Imaging means for imaging the eyeball;
Based on the image of the eyeball imaged by the imaging means, rotation detection means for detecting the rotation of the eyeball accompanying the tilt of the head of the subject in the left-right direction;
A target correcting means for correcting the presentation position of the target presented by the display means according to the rotation of the eyeball;
It is a visual inspection apparatus having
The second aspect of the present invention is:
The rotation detection means includes
Reference image holding means for holding, as a reference image, an image of the eyeball imaged by the imaging means when the subject's head is in a reference state;
The in-use image, which is the image of the eyeball imaged by the imaging means when the subject is in use, is pattern-matched with the reference image, and the rotation angle of the in-use image with respect to the reference image is measured. Rotation angle measuring means;
Have
The visual target correction device according to the first aspect, wherein the visual target correction unit corrects a presentation position of the visual target presented by the display unit according to the rotation angle measured by the rotation angle measurement unit.
The third aspect of the present invention is:
Each of the reference image and the in-use image is the visual inspection device according to the second aspect including an iris image of the eyeball.
The fourth aspect of the present invention is:
A display optical system for guiding the light of the optotype presented by the display means to the retina of the eyeball;
An observation optical system for guiding the image of the eyeball to the image sensor;
Have
The display optical system has a mirror that reflects light of a specific wavelength and transmits other light on the eyeball side of the display element,
Any one of the first to third aspects in which an optical axis from the pupil of the eyeball of the display optical system to the mirror coincides with an optical axis from the pupil of the eyeball of the observation optical system to the mirror. The visual inspection device according to claim 1.
According to a fifth aspect of the present invention,
A method for correcting a target of a head-mounted visual inspection apparatus to be mounted on a subject's head,
Detecting the rotation of the eyeball associated with the tilt of the head of the subject in the left-right direction based on an image of the eyeball;
Correcting the presentation position of the visual target to be presented to the eyeball of the subject according to the rotation of the eyeball;
It is the optotype correction method of the visual inspection apparatus which has.
The sixth aspect of the present invention is:
The step of detecting the rotation of the eyeball comprises:
A reference image holding step for holding an image of the eyeball imaged when the head of the subject is in a reference state as a reference image;
An in-use image acquisition step of acquiring an in-use image that is an image of the eyeball imaged when the subject is in use; and
Pattern-matching the in-use image with the reference image and measuring a rotation angle of the in-use image with respect to the reference image;
Have
In the target correction step,
The visual target correction method for a visual inspection device according to a fifth aspect, wherein the display position of the visual target presented by the display means is corrected according to the rotation angle.
The seventh aspect of the present invention is
A head-mounted display device mounted on a user's head,
Display means for displaying an image on the eyeball of the user;
Imaging means for imaging the eyeball;
Based on the image of the eyeball imaged by the imaging means, rotation detection means for detecting the rotation of the eyeball accompanying the tilt of the head of the subject in the left-right direction;
Image correcting means for correcting the display position of the image displayed by the display means in accordance with the rotation of the eyeball;
It is a display apparatus which has.

  According to the present invention, it is possible to provide a head-mounted visual inspection apparatus that accurately performs visual field inspection even when the eyeball is rotated, a target correction method for the visual inspection apparatus, and a display device.

It is the schematic of the visual inspection apparatus of this embodiment. It is a section schematic diagram of the visual inspection device of this embodiment. It is the schematic which shows the structure of the control part in the visual inspection apparatus of this embodiment. It is a flowchart which shows the optotype correction method of the visual inspection apparatus of this embodiment. (A) is a figure when a subject's head is in a reference state, (b) is a figure showing an image of the eyeball of a subject when the subject's head is in a reference state. It is. (A) is a figure when a subject is a use state, (b) is a figure which shows the image of the eyeball of a subject when a subject is a use state. (A) is a figure which shows a reference | standard image, (b) is a figure which shows an image in use, (c) is a figure when pattern matching of a reference image and an image in use is carried out. (A) is a figure which shows a visual target when a subject's head is a reference | standard state, (b) is a figure which shows a visual target when a subject is a use state. It is the schematic which shows the structure of the control part in the display apparatus of other embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the present embodiment, description will be given in the following order.
1. Visual inspection device 1-1. Display optical system and display element 1-2. Observation optical system and imaging device 1-3. Control unit 2. 2. Visual inspection method 3. Target correction method of visual inspection device 4. Effects of the embodiment Other Embodiments 5-1. Control unit 5-2. 5. Image correction method for display device Modifications etc.

<1. Visual inspection device>
FIG. 1 is a schematic diagram of a visual inspection apparatus according to this embodiment. As shown in FIG. 1, the visual inspection device 10 of the present embodiment is configured as a head-mounted visual inspection device that is attached to the head of a subject for visual field inspection. Specifically, the visual inspection device 10 includes, for example, a head mount (HM) unit 100 and a control unit 400.

  The HM unit 100 includes a housing (mounting main body) 110 and a mounting tool 120 connected to the housing 110, and is configured to be mounted on the subject's head by the mounting tool 120. The housing 110 stores a display optical system (200) and an observation optical system (300), which will be described later. For example, a display optical system (200) is provided in each of both eyes, and a display element (display means) 240R corresponding to the right eye and a display element 240L corresponding to the left eye are provided in the housing 110. ing. In addition, the wearing tool 120 includes a first belt that is bridged in a U-shape from both sides of the subject to the back of the head, and a second belt that is spanned to the top of the subject. The second belt may be configured to be adjustable in length.

  The control unit 400 is configured to control the display optical system (200), the observation optical system (300), and the like. Moreover, the control part 400 is arrange | positioned at the back head side of the mounting tool 120, for example. Thereby, the weight balance before and behind the housing 110 and the control part 400 can be maintained. Details of the control unit 400 will be described later.

  FIG. 2 is a schematic cross-sectional view of the visual inspection apparatus of the present embodiment. As shown in FIG. 2, the visual inspection device 10 according to the present embodiment includes a display optical system 200 for presenting a visual target to the eyeball 20, and an observation optical system 300 for imaging the eyeball 20. ,have. Hereinafter, an example of the optical system of the visual inspection apparatus 10 will be described in detail.

  FIG. 2 shows an optical system (display optical system 200 and observation optical system 300) corresponding to one eye. For example, the optical systems corresponding to the left and right eyes have the same configuration. have. In the following description, the optical systems corresponding to the left and right eyes will be described without distinction, and the L and R symbols will be omitted.

(1-1. Display optical system and display element)
The display optical system 200 is configured to guide light of a predetermined target to the retina 22 of the eyeball 20. The “target” here is a point or a figure that is presented to the eyeball of the subject during the visual field inspection. The display optical system 200 includes, for example, a first lens 210, a mirror 220, and a second lens group 230 in order from the eyeball 20 side.

  The first lens 210 functions as an objective lens when the eyeball 20 is an object, and is configured as a positive lens, for example. The optical axis 280a of the first lens 210 is disposed so as to pass through the center of the pupil 21 of the eyeball 20 (the center of the eyeball 20).

  The mirror 220 is configured to reflect light of a specific wavelength and transmit other light. Specifically, the mirror 220 is configured as a cold mirror that reflects visible light and transmits infrared light, for example. The mirror 220 is provided on the side opposite to the eyeball 20 on the optical axis 280a of the first lens 210 with the first lens 210 interposed therebetween. The mirror 220 is provided to be inclined at a predetermined angle with respect to the optical axis 280a of the first lens 210. On the other hand, the mirror 220 transmits infrared light reflected on the surface of the eyeball 20 described later to the side opposite to the eyeball 20 of the mirror 220.

  The second lens group 230 is provided on the optical axis 280b in the direction of reflecting through the mirror 220 with respect to the optical axis 280a of the first lens 210. That is, the optical axis 280 a from the pupil 21 of the eyeball 20 of the display optical system 200 to the mirror 220 and the optical axis 280 b from the mirror 220 of the display optical system 200 to the display element 240 are reflected from each other via the mirror 220. Is bent.

  The second lens group 230 includes at least a lens having a positive refractive power and a lens having a negative refractive power in order to correct the chromatic aberration of the display optical system 200. Specifically, the second lens group 230 includes, for example, in order from the eyeball 20 side, a positive lens 232, a negative lens 234, and a positive meniscus lens 236 convex to the eyeball 20 side.

  The display element (display unit) 240 is configured to present a predetermined visual target to the eyeball 20. The predetermined target is, for example, a fixed target such as a cross or a stimulus target having a predetermined brightness (luminance) for visual field inspection. The display element 240 is configured as, for example, a liquid crystal display element or an organic EL display element.

  The display element 240 is provided on the opposite side of the mirror 220 across the second lens group 230 on the optical axis 280 b of the second lens group 230. The display surface of the display element 240 is arranged so that the normal direction thereof coincides with the optical axis 280 b of the second lens group 230. Further, the display element 240 is disposed at a position optically conjugate with the retina 22 via the first lens 210, the mirror 220, and the second lens group 230.

  The display element 240 is connected to the control unit 400 and is configured to present a predetermined target to the eyeball 20 based on a signal from the control unit 400.

(1-2. Observation optical system and imaging device)
The observation optical system 300 is configured to guide an image of the eyeball 20 (such as an image of the iris 24 and the pupil 21) to the image sensor 340. Specifically, the observation optical system 300 includes, for example, in order from the eyeball 20 side, a light source 310, a first lens 210 shared with the display optical system 200, and a mirror 220 shared with the display optical system 200. And an imaging lens 320.

  A light source 310 that illuminates the eyeball 20 is provided between the eyeball 20 and the first lens 210 at a position outside the light beam passage range of the first lens 210. For example, two light sources 310 are provided in the horizontal direction (or vertical direction) across the eyeball 20. The light source 310 is configured as an LED light source that irradiates infrared light, for example. By irradiating the eyeball 20 with infrared light, the eyeball 20 of the subject can be imaged without being detected by the retina 22 of the subject.

  In the observation optical system 300, since the first lens 210 and the mirror 220 are shared with the display optical system 200, the optical axis 280 a from the pupil 21 of the eyeball 20 of the display optical system 200 to the mirror 220 is changed to the observation optical system 300. This coincides with the optical axis (280a) from the pupil 21 of the eyeball 20 to the mirror. Thereby, the target presentation position by the display element 240 and the position in the image of the eyeball 20 imaged by the image sensor 340 can be matched (matched).

  As described above, the mirror 220 shared with the display optical system 200 transmits the infrared light irradiated from the light source 310 and reflected by the surface of the eyeball 20.

  The imaging lens 320 is configured as a relay lens that forms an image of infrared light transmitted through the mirror 220 on the imaging element 340. The optical axis 380a of the imaging lens 320 coincides with the optical axis 380a of the first lens 210 (positioned on the same axis).

  The imaging element (imaging means) 340 is configured to image the eyeball 20 by detecting infrared light. Specifically, for example, as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), for example. It is configured. The imaging element 340 is provided on the opposite side of the mirror 220 with the imaging lens 320 sandwiched on the optical axis 380 a of the imaging lens 320. The imaging surface of the imaging element 340 is arranged so that the normal direction thereof coincides with the optical axis 380 a of the imaging lens 320. In addition, the image sensor 340 is connected to the control unit 400 and configured to transmit an image obtained by capturing the eyeball 20 to the control unit 400.

(1-3. Control unit)
FIG. 3 is a schematic diagram illustrating a configuration of a control unit in the visual inspection apparatus according to the present embodiment. The control unit (computer unit) 400 of the present embodiment is for performing various controls related to the visual inspection device 10, and specifically, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM ( It consists of a combination of Read Only Memory (HDD), HDD (Hard disk drive), various interfaces and the like. And the control part 400 is comprised so that CPU may function as various means (410-450), when a predetermined program stored in ROM or HDD is executed.

  The control unit 400 is connected to the display element 240 and the image sensor 340 so that they can communicate with each other by wire or wirelessly (A, B), and is configured to control the display element 240 and the image sensor 340.

  Here, the functions realized by the predetermined program of the control unit 400 of this embodiment are a visual field inspection function that is an operation control function necessary for visual field inspection, and a target correction control that corrects the presentation position of the visual target in the visual field inspection. It is divided into functions. The visual field inspection function includes a target presentation unit 410, a miosis detection unit 420, and a sensitivity mapping unit 430. On the other hand, the target correction control function in the visual field inspection includes a rotation detection unit 440 and a target correction unit 450.

The visual inspection device 10 of the present embodiment is configured to be able to perform a subjective visual field inspection described later, and the control unit 400 is configured to function as sensitivity mapping means 430 that is a visual field inspection function. Yes.
For example, a switch 520 is provided in the vicinity of the subject so that the subject can answer whether the target is visible. The switch 520 is connected to the control unit 400 (C), and is configured to transmit a signal indicating that the subject has visually recognized the control unit 400.
The sensitivity mapping means 430 of the control unit 400 is a function for mapping the luminance of the display element 240 when the visual target becomes visible as the sensitivity of the retina 22 based on the signal transmitted from the switch 520.

Furthermore, the visual inspection device 10 of the present embodiment is also configured to be able to perform an objective visual field inspection, which will be described later, and the control unit 400 includes a visual target presenting means 410 that is a visual field inspection function, a miosis. The detection unit 420 and the sensitivity mapping unit 430 are configured to function.
The optotype presenting means 410 is a function for causing the display element 240 to present the optotype.
The miosis detection means 420 is based on the image of the pupil 21 acquired by the image sensor 340, and reduces the pupil 21 when the brightness of the target presented by the display element 240 is equal to or higher than a predetermined brightness (luminance). This is a function for detecting the pupil.
The sensitivity mapping means 430 is a function used not only in the subjective visual field examination but also in the objective visual examination, and the visual field that the display element 240 presented when the miosis detection means detects the miosis of the pupil 21. This is a function for mapping the brightness (luminance) of the mark as the sensitivity of the retina 22.

Further, the visual inspection device 10 of the present embodiment is configured to correct the presentation position of the target in accordance with the rotation of the eyeball 20 in the visual field inspection, and the control unit 400 has a target correction control function. The rotation detection unit 440 and the target correction unit 450 are configured to function.
The rotation detection unit 440 is a function for detecting the rotation of the eyeball 20 based on the image of the eyeball 20 imaged by the image sensor 340. For example, the rotation detection unit 440 includes a reference image holding unit 442 and a rotation angle measurement unit 446. Yes.
The reference image holding unit 442 is a function for holding the image of the eyeball 20 captured by the image sensor 340 as a reference image when the subject's head is in the reference state.
The rotation angle measurement unit 446 pattern-matches the in-use image, which is the image of the eyeball 20 captured by the image sensor 340 when the subject is in use, with the reference image, and rotates the rotation angle of the in-use image with respect to the reference image. It is a function for measuring.
The target correction means 450 is a function for correcting the presentation position of the target presented by the display element 240 in accordance with the rotation of the eyeball 20.

The predetermined program for realizing each of these functions is installed and used in the control unit 400, but may be provided by being stored in a storage medium readable by the control unit 400 prior to the installation. Alternatively, it may be provided to the control unit 400 through a communication line connected to the control unit 400.
The control unit 400 in which the predetermined program is installed may not necessarily be mounted on the visual inspection device 10 as long as it can give an operation control instruction to each unit of the visual inspection device 10. It may be connected to the inspection apparatus 10 via a communication line.

<2. Visual inspection method>
Next, the visual inspection method by the visual inspection apparatus 10 of this embodiment is demonstrated. The visual inspection apparatus 10 according to the present embodiment can perform dynamic quantitative visual field inspection, static quantitative visual field inspection, fundus visual field inspection (microperimetry), electroretinography (ERG), and other inspections. Below, the case where a static quantitative visual field inspection is performed is demonstrated. As for the static quantitative visual field inspection, there are a subjective visual field inspection and an objective visual field inspection, and the visual inspection apparatus 10 according to the present embodiment can perform any type of inspection.

  A subjective visual field inspection is performed as follows. First, the HM unit 100 of the visual inspection apparatus 10 is attached to the subject's head, and the subject is provided with the switch 520. The optotype presenting means 410 of the control unit 400 causes the display element 240 to present the optotype at one point in the field of view, and gradually increases the brightness of the optotype. When the brightness of the target becomes equal to or higher than the predetermined brightness, the subject can see the target. At this time, the subject presses the switch 520. Then, a signal indicating that the subject has visually recognized is transmitted from the switch 520 to the control unit 400. Based on the signal transmitted from the switch 520, the sensitivity mapping unit 430 of the control unit 400 presents the target with a value corresponding to the brightness of the target when the target becomes visible. Retinal sensitivity at point. By performing the same measurement for each point in the field of view, the sensitivity mapping means 430 of the control unit 400 creates a map of the sensitivity of the retina 22 in the field of view.

  The objective visual field inspection is performed as follows. First, the HM unit 100 of the visual inspection device 10 is attached to the subject's head. In this case, the subject need not have the switch 520. The optotype presenting means 410 of the control unit 400 causes the display element 240 to present the optotype at one point in the field of view, and gradually increases the brightness of the optotype. At the same time, the light source 310 irradiates the subject's eyeball 20 with infrared light, and the imaging element 340 images the pupil 21 of the subject's eyeball 20. When the brightness of the visual target becomes equal to or higher than the predetermined brightness, the subject can see the visual target when the retina 22 of the subject senses the light of the visual target. At this time, the pupil of the subject changes (miosis) according to the brightness of the visual target. The miosis detection means 420 of the control unit 400 performs image analysis based on the image of the pupil 21 acquired by the imaging element 340, so that the brightness of the target presented by the display element 240 becomes equal to or higher than a predetermined brightness. The miosis of the pupil 21 is detected. When the miosis detection means 420 of the control unit 400 detects the miosis of the pupil 21, the sensitivity mapping means 430 of the control unit 400 displays the display element when the miosis detection means 420 detects the miosis of the pupil 21. The brightness of the visual target presented by 240 is defined as the sensitivity of the retina 22. By performing the same measurement for each point in the visual field, the sensitivity mapping means 430 of the control unit 400 automatically creates a map of the retina 22 sensitivity in the visual field.

  In the objective test, a single target threshold for creating a sensitivity map by displaying a bright target on one point of the display element 240 and observing the degree of reduction of the pupil diameter of the pupil 21 detected by the pupil detection means 420. The top stimulation method may be used.

<3. Target correction method for visual inspection device>
In the visual field inspection as described above, the subject may tilt his / her head to the left or right due to fatigue caused by concentrating on the visual field inspection. When the subject's head tilts left and right, a phenomenon in which the eyeball 20 rotates in a direction opposite to the tilting direction of the head, so-called rotation of the eyeball 20 may occur. Therefore, in the present embodiment, when the eyeball 20 is rotated in the visual inspection, the presentation position of the visual target is corrected as follows.

  FIG. 4 is a flowchart showing the target correction method of the visual inspection apparatus according to this embodiment. The flow of the target correction method shown in FIG. 4 is performed at the time of the visual field inspection described above. Only the target correction method for the right eye of the subject will be described below, but the same target correction method is also applied to the left eye. Note that the correction of the target position for the right eye may be applied to the correction of the target position for the left eye at the same time. You may apply to correction | amendment of the presentation position of the optotype with respect to eyes.

  First, as described below, based on the image of the eyeball 20 imaged by the image sensor 340, the rotation of the eyeball 20 accompanying the tilt of the subject's head in the left-right direction is detected. In the following, step is abbreviated as “S”.

(S110: Reference image holding step)
FIG. 5A is a diagram when the subject's head is in the reference state.
FIG. 5A shows a state where the subject wears the visual inspection device 10 on the head before starting the visual field inspection. At this time, the head of the subject stands upright along the vertical direction, and both eyes of the subject are positioned horizontally. The initial state in which the subject wears the visual inspection device 10 on the head in this way is referred to as a “reference state”.

FIG. 5B is a diagram illustrating an image of the eyeball of the subject when the subject's head is in the reference state. In FIG. 5B, the upper side of the right eye is U, the lower side is D, the left side is L, and the right side is R as viewed from the subject. That is, on the paper surface, the right side is L and the left side is R. Moreover, U, D, L, and R are similarly illustrated in FIGS.
As illustrated in FIG. 5B, when the subject's head is in the reference state, the imaging element 340 acquires an image of the eyeball 20 and transmits the image to the control unit 400. In the control unit 400, the reference image holding unit 442 holds the image of the eyeball 20 when the subject's head is in the reference state as the “reference image P1” (S110). At this time, since the optical axis 380a of the observation optical system 300 that guides the image of the eyeball 20 to the image sensor 340 passes through the center of the eyeball 20, the center of the reference image P1 is the center of the eyeball 20. (Ie, the center of the pupil 21). It is assumed that the center of the image captured by the image sensor 340 does not move from the center of the eyeball 20 in subsequent visual field inspections. At this time, in the reference image P1, a line that passes through the center of the eyeball 20 and is parallel to the vertical direction of the head (UD direction) is referred to as a “head direction centerline 20c of the eyeball 20”.

  Further, the reference image P1 includes an image of the iris 24 of the eyeball 20. Since the iris 24 has an up-down / left-right asymmetric unique pattern for each subject, the image of the iris 24 in the reference image P1 is used to measure the rotation angle of the eyeball 20, as will be described later.

(S120: In-use image acquisition process)
After the reference image holding step S110, the visual field inspection described above is started. Hereinafter, the state in which the subject is performing the visual field inspection is referred to as a state in which the subject is using the visual inspection apparatus 10, that is, a “use state”.

FIG. 6A is a diagram when the subject is in use.
FIG. 6A shows a state in which the subject tilts his / her head in the right (R) direction at the time of visual field inspection, for example. Here, when facing the subject, the direction counterclockwise (right (R) direction of the head) is taken as the positive direction. In the case of FIG. 6A, the subject's head is inclined in the positive direction, and the inclination angle of the subject's head with respect to the vertical direction is + α (α ≧ 0).

FIG. 6B is a diagram illustrating an image of the eyeball of the subject when the subject is in use.
As shown in FIG. 6B, when the subject is in use, the imaging device 340 acquires an image of the eyeball 20 at a predetermined time interval, for example, in order to grasp the state of the eyeball 20. Then, the image is transmitted to the control unit 400 (S120). At this time, an image of the eyeball 20 captured by the image sensor 340 when the subject is in use is referred to as an “in-use image P2”.

  For example, in the state of FIG. 6B, the head direction centerline 20c of the eyeball 20 is in the vertical direction because the subject's head is inclined in the positive direction (R direction) at an angle of + α. Tilted at an angle of + α. On the other hand, the eyeball 20 of the subject rotates around the center of the eyeball 20 in the direction opposite to the tilt direction of the head. At this time, the rotation angle of the eyeball 20 with respect to the head direction center line 20c of the eyeball 20 is assumed to be, for example, -β (β in the direction opposite to the head tilt direction) (β ≧ 0). For example, the absolute value β of the rotation angle of the eyeball 20 is smaller than the absolute value α of the tilt angle of the subject's head. At this stage, the control unit 400 does not recognize that the rotation angle of the eyeball 20 is −β.

  Further, the in-use image P2 also includes the image of the iris 24 as in the reference image P1. The pattern of the iris 24 in the in-use image P <b> 2 rotates at an angle of −β with respect to the center line 20 c in the head direction of the eyeball 20 as the eyeball 20 rotates.

(S130: rotation angle measurement process)
Next, the rotation angle of the eyeball 20 when the subject is in use is measured as follows.

FIG. 7A is a diagram illustrating a reference image, and FIG. 7B is a diagram illustrating an in-use image.
As shown in FIG. 7A, the control unit 400 acquires the reference image P1, and then removes the eyelid 20 from the eyeball 20 to extract the iris 24 from the reference image P1. Image processing such as processing, contrast adjustment processing for adjusting the contrast of the iris 24 pattern, and edge enhancement processing for enhancing the edge of the iris 24 pattern is performed.
Further, as shown in FIG. 7B, after acquiring the in-use image P2, the control unit 400 obtains the in-use image P2 and performs the same iris extraction process and contrast adjustment process as the reference image P2. Image processing such as edge enhancement processing is performed.

  Note that when the subject is in use, the imaging device 340 that images the eyeball 20 is mounted on the head as a head-mounted type, and therefore tilts with the head (follows the tilt of the head). Is in a state. For this reason, the tilt of the head cannot be grasped from the in-use image P2 in FIG. 7B, and only an image in which the iris 24 (eyeball 20) is rotated at an angle of −β is obtained.

FIG. 7C is a diagram when pattern matching is performed on the reference image and the image in use.
As shown in FIG. 7C, the rotation angle measuring unit 446 performs pattern matching between the image of the iris 24 in the in-use image P2 and the image of the iris 24 in the reference image P1, for example, as follows. Then, the rotation angle of the in-use image P2 with respect to the reference image P1 is measured.

  First, the reference image P1 is superimposed on the in-use image P2, and the difference between the image of the iris 24 in the reference image P1 and the image of the iris 24 in the in-use image P2 is detected. Next, the reference image P1 is gradually rotated around the center (pupil 21) of the reference image P1, and the difference between the image of the iris 24 in the rotated reference image P1 and the image of the iris 24 in the in-use image P2 is different. Repeat until is minimized. When the difference of the image of the iris 24 in the reference image P1 after rotation with respect to the image of the iris 24 in the in-use image P2 is minimized, the angle at which the reference image P1 is rotated is set to the angle of the in-use image P2 with respect to the reference image P1. The rotation angle is measured (calculated) (S130). The rotation angle (−β) of the in-use image P2 with respect to the reference image P1 thus obtained corresponds to the rotation angle (−β) of the eyeball 20 when the subject is in use. In the next step, the rotation angle (−β) of the in-use image P2 with respect to the reference image P1 is used as the rotation angle (−β) of the eyeball 20 to correct the presentation position of the visual target.

(S140: Target correction process)
Next, the visual target correction means 450 corrects the display position of the visual target presented by the display element 240 according to the rotation of the eyeball 20, for example, as follows.

Here, Fig.8 (a) is a figure which shows a visual target when a subject's head is a reference | standard state. FIG. 8A and FIG. 8B to be described later show a view when the display image of the display element 240 is seen through the display element 240 from the opposite side.
FIG. 8A shows a display screen TP1 of the display element 240 when the subject's head is in the reference state. In the display screen TP1 when the subject's head is in the reference state, the center of the display screen TP1 is arranged at the center position of the eyeball 20, and the fixed target O is presented at the center of the display screen TP1. A target (stimulus target) T1 is presented at a predetermined position away from the target O. In FIG. 8A, the fixed target O is shown as a black cross and the target T1 is shown as a black dot. However, in reality, the background is dark with a predetermined brightness (luminance) or less. The fixed target O is a cross having a predetermined brightness (luminance), and the target T1 is a point having a predetermined brightness (luminance) for inspection.

On the other hand, FIG.8 (b) is a figure which shows a visual target when a subject is a use condition.
Here, when the subject is in use and the subject's head is tilted, the display element 240 that presents the target T1 is mounted on the head as a head-mounted type. Tilted together (follows the tilt of the head). If the display screen TP1 of the display element 240 is maintained, the presentation position of the visual target T1 is the presentation position of the visual target T1 when the subject's head is in the reference state (dotted line in FIG. 8B). The same as the circle). On the other hand, at this time, as described above, the eyeball 20 of the subject is rotated at an angle of −β in the direction opposite to the tilt direction of the head. The presentation position of the visual target T1 with respect to the eyeball 20 at the time of rotation is relatively shifted in the direction opposite to the rotational direction of the eyeball 20 from the presentation position of the visual target T1 with respect to the eyeball 20 before the rotation. As described above, in a state where the presentation position of the target T1 is deviated, an accurate inspection cannot be performed on the target presentation position of the target T1 on the retina 22.

Therefore, in this embodiment, as shown in FIG. 8B, the visual target correction means 450 is a visual display that the display element 240 presents according to the rotation angle −β measured by the rotation angle measurement means 446. The presentation position of the mark T1 is corrected. Specifically, the target correcting means 450 rotates the target T1 when the subject's head is in the reference state at the same angle as the rotation angle −β of the eyeball 20 around the center of the display screen TP1. Let the target T2 be when the subject is in use. That is, the rotation angle −β of the eyeball 20 obtained in the rotation angle measurement step S140 is set as an angle (−β) for correcting the presentation position of the target T1 as it is. For example, when the coordinates of the target T1 are (x ₁ , y ₁ ), the coordinates of the target T1 are rotated by an angle of −β, and the coordinates of the target T2 are (x ₁ cos β + y ₁ sin β, −x ₁ sin β + y ₁ cos β). At this time, the fixed visual target O may be rotated around the center of the display screen TP1 at the same angle as the rotation angle −β. Further, it may be considered that the entire display screen TP1 of the display element 240 is rotated around the center of the display screen TP1 at the same angle as the rotation angle −β to be corrected to the virtual display screen TP2.

  In this way, by correcting the presentation position of the target T1 presented by the display element 240 according to the rotation angle −β measured by the rotation angle measuring means 446, the head of the subject is tilted and the eyeball 20 is tilted. Even when the eye is rotated, the position of the visual target on the eyeball 20 during the rotation is the same as the position of the visual target on the eyeball 20 before the rotation (when the subject's head is in the reference state). (S140).

(S150: Inspection end determination)
Thereafter, the control unit 400 determines whether or not to end the visual field inspection (S150). When continuing the visual field inspection without ending (No in S150), the steps from the in-use image acquisition step S120 to the target correction step S140 are repeated again. On the other hand, when the visual field inspection is finished (Yes in S150), the series of steps is finished.

  In addition, even when the subject is in use, the case where the subject's head is not tilted, that is, α = 0 may be considered. In this case, the eyeball 20 does not rotate. In this embodiment, even when the subject's head is not tilted, the steps from the in-use image acquisition step S120 to the target correction step S140 are performed. That is, in the in-use image acquisition step S120, the in-use image P2 in which the eyeball 20 is not rotated is acquired. In the rotation angle measurement step S130, the rotation angle β = 0 of the eyeball 20 is measured. In the visual target correction step S140, the presentation position of the visual target T1 is corrected with the rotation angle β = 0. In other words, the presentation position of the target T1 is not corrected.

<4. Advantages of the embodiment>
According to the embodiment of the present invention, the following effects can be obtained.

(A) According to the present embodiment, the rotation detection unit 440 detects the rotation of the eyeball 20 based on the image of the eyeball 20 captured by the image sensor 340. The visual target correction means 450 corrects the display position of the visual target presented by the display element 240 according to the rotation of the eyeball 20. As a result, even when the subject's head is tilted and the eyeball 20 is rotated, the presentation position of the target T1 with respect to the eyeball 20 at the time of rotation is the same as before rotation (the subject's head is in a reference state). It is possible to suppress the relative displacement in the direction opposite to the rotation direction of the eyeball 20 from the position where the target T1 is presented with respect to the eyeball 20 at a certain time. Therefore, even when the subject's head is tilted and the eyeball 20 is rotated, an accurate examination can be performed on the target target presentation position on the retina 22.

(B) According to the present embodiment, first, in the reference image holding step S110, when the subject's head is in the reference state, the image of the eyeball 20 imaged by the image sensor 340 is held as the reference image P1. In addition, in the rotation angle measurement step S130, when the subject is in use, the in-use image P2, which is the image of the eyeball 20 imaged by the image sensor 340, is pattern-matched with the reference image P1, and the reference image P1. The rotation angle -β of the in-use image P2 with respect to is measured. The rotation angle −β of the in-use image P2 with respect to the reference image P1 thus obtained corresponds to the rotation angle −β of the eyeball 20 when the subject is in use. That is, the rotational angle −β of the eyeball 20 can be accurately measured by pattern matching the in-use image P2 with the reference image P1. Then, in the target correction step S140, the display position of the target T1 presented by the display element 240 is corrected according to the rotation angle −β of the in-use image P2 with respect to the reference image P1, whereby the eyeball 20 at the time of rotation is corrected. The presentation position of the visual target can be made the same as the presentation position of the visual target with respect to the eyeball 20 before rotation (when the subject's head is in the reference state). Therefore, even when the subject's head is tilted and the eyeball 20 is rotated, the accuracy of the visual field inspection can be improved.

(C) According to the present embodiment, each of the reference image P1 and the in-use image P2 includes an image of the iris 24 of the eyeball 20. The image of the iris 24 in each of the reference image P1 and the in-use image P2 is used for pattern matching in the rotation angle measurement step S130. Since the iris 24 has a specific pattern that is asymmetrical in the vertical and horizontal directions for each subject, the image of the iris 24 in the in-use image P2 is pattern-matched with the image of the iris 24 in the reference image P1, thereby generating the reference image P1. The rotation angle -β of the in-use image P2 can be easily measured.

  Here, for reference, a case where the rotation angle of the eyeball is measured using the fundus image will be described. The fundus including the retina also has a unique pattern that is asymmetrical in the vertical and horizontal directions for each non-examiner. By pattern matching the fundus image at the time of rotation with the fundus image before the rotation, the rotation angle of the eyeball can be measured based on the same principle as in the present embodiment. However, in this case, the observation optical system for observing the fundus is likely to be large. In connection with this, the whole visual inspection apparatus may be enlarged. On the other hand, according to the present embodiment, the rotation angle of the eyeball 20 can be easily measured by using the image of the iris 24 on the surface (anterior eye portion) of the eyeball 20 for pattern matching. Accordingly, the observation optical system 300 can have a simple configuration for observing only the surface (anterior eye portion) of the eyeball 20. Therefore, the entire visual inspection apparatus can be reduced in size.

(D) According to this embodiment, the optical axis 280a from the pupil 21 of the eyeball 20 of the display optical system 200 to the mirror 220 is the optical axis (280a) from the pupil 21 of the eyeball 20 of the observation optical system 300 to the mirror. Match. Thereby, the target presentation position by the display element 240 and the position in the image of the eyeball 20 imaged by the image sensor 340 can be matched (matched). When the subject's head is tilted and the eyeball 20 is rotated, if the rotation angle (−β) of the eyeball 20 is obtained on the image of the eyeball 20 by the imaging device 340, the rotation angle (−β) of the eyeball 20 is calculated. The angle (−β) for correcting the presentation position of the target as it is can be used. Thus, the angle for correcting the presentation position of the visual target can be obtained easily and accurately.

<5. Other embodiments>
The present invention can be realized not only as a visual inspection apparatus but also as a head mounted display. The present embodiment is different from the previous embodiment in that “subject” is replaced as “user” and the configuration of the control unit 400 is different. Note that the present embodiment is different from the conventional head-mounted display device in that it includes an observation optical system 300 and an image sensor 340 for imaging the eyeball 20.

(5-1. Control unit)
FIG. 9 is a schematic diagram illustrating a configuration of a control unit in a display device according to another embodiment.
As shown in FIG. 9, the display device 12 of the present embodiment is configured to display a predetermined image for the user, and the control unit 400 serves as the image control unit 470. Configured to work.
The image control unit 470 is a function for controlling the display element 240 to display a predetermined image.
The image displayed on the display element 240 is not particularly limited, and may be either a still image or a moving image (game or movie video). Also, the image to be displayed is not limited to a two-dimensional image, and may be a three-dimensional image so as to be different on the left and right.

Further, the display device 12 of the present embodiment is configured to correct the display position of the image according to the rotation of the eyeball 20 when used by the user. The control unit 400 includes the rotation detection unit 440 and the rotation detection unit 440. The image correction unit 480 is configured to function.
The rotation detection unit 440 has the same function as that of the previous embodiment, and is a function for detecting the rotation of the eyeball 20 based on the image of the eyeball 20 captured by the image sensor 340.
The image correction unit 480 is a function for correcting the display position of the image displayed on the display element 240 in accordance with the rotation of the eyeball 20.

(5-2. Image correction method of display device)
The image correction method of the display device of the present embodiment is different from the target correction method of the visual inspection device of the previous embodiment in that an image correction step S140 is performed instead of the target correction step S140.

  In the image correction step S140, the image correction unit 480 corrects the display position (display angle) of the image displayed on the display element 240 in accordance with the rotation angle −β measured by the rotation angle measurement unit 446. Specifically, the image correction unit 480 rotates the image (the whole) when the subject's head is in the reference state at the same angle as the rotation angle −β of the eyeball 20 around the center of the display screen. Let the image be when the subject is in use.

  According to this embodiment, by correcting the display position of the image displayed by the display element 240 according to the rotation angle −β measured by the rotation angle measuring unit 446, the head of the subject is tilted and the eyeball 20 is tilted. Even when the image is rotated, the display position of the image on the eyeball 20 at the time of rotation is not changed from the display position of the image on the eyeball 20 before the rotation (when the subject's head is in the reference state). can do.

<6. Modified example>
The present invention is not limited to the contents of the above-described embodiment, and can be appropriately changed without departing from the gist thereof.

  In the above-described embodiment, the case where the control unit 400 is provided on the back head side of the wearing tool 120 has been described, but the control unit may be stored in the housing of the HM unit. Further, the control unit may be provided separately from the HM unit.

  In the above-described embodiment, the case where the first lens 210 of the display optical system 200 is configured by one lens has been described. However, the first lens may be a lens group configured by a plurality of lenses.

  In the above-described embodiment, the case where the mirror 220 is a cold mirror has been described. However, the mirror may be a hot mirror or a dichroic mirror.

  In the above-described embodiment, the case where the optical axis of the display optical system 200 is bent through the mirror 220 has been described. However, the display optical system is linearly arranged and the observation optical system is bent through the mirror. May be.

  In the embodiment described above, the optical axis 280b from the mirror 220 of the display optical system 200 to the display element 240 is positioned vertically above the optical axis from the pupil 21 of the eyeball 20 of the display optical system 200 to the mirror 220. As described above, the optical axis from the mirror of the display optical system to the display element may be positioned vertically lower than the optical axis from the pupil of the eyeball of the display optical system to the mirror.

  In the above-described embodiment, in the target correction step S140, the case where the presentation position of the target is corrected (moved) within the screen of the display element 240 according to the rotation angle −β of the eyeball 20 has been described. In the target correction step, the display element itself may be rotated about the optical axis according to the rotation angle of the eyeball.

DESCRIPTION OF SYMBOLS 10 Visual test | inspection apparatus 12 Display apparatus 20 Eyeball 21 Pupil 22 Retina 24 Iris 100 Head mount (HM) part 110 Housing (mounting main body)
120 Mounting tool 200 Display optical system 210 First lens 220 Mirror 230 Second lens group 232 Positive lens 234 Negative lens 236 Positive meniscus lenses 240, 240R, 230L Display elements 280a, 280b Optical axis 300 Observation optical system 310 Light source 320 Imaging lens 340 Image sensor 380a Optical axis 400 Control unit (computer unit)
410 target presentation means 420 miosis detection means 430 sensitivity mapping means 440 rotation detection means 442 reference image holding means 446 rotation angle measurement means 450 target correction means 470 image control means 480 image correction means 520 switch

Claims (7)

A head-mounted visual inspection device mounted on a subject's head,
Display means for presenting a visual target to the eyeball of the subject;
Imaging means for imaging the eyeball;
Based on the image of the eyeball imaged by the imaging means, rotation detection means for detecting the rotation of the eyeball accompanying the tilt of the head of the subject in the left-right direction;
A target correcting means for correcting the presentation position of the target presented by the display means according to the rotation of the eyeball;
Visual inspection apparatus having The rotation detection means includes
Reference image holding means for holding, as a reference image, an image of the eyeball imaged by the imaging means when the subject's head is in a reference state;
The in-use image, which is the image of the eyeball imaged by the imaging means when the subject is in use, is pattern-matched with the reference image, and the rotation angle of the in-use image with respect to the reference image is measured. Rotation angle measuring means;
Have
The visual inspection apparatus according to claim 1, wherein the visual target correction unit corrects a display position of the visual target presented by the display unit according to the rotation angle measured by the rotation angle measurement unit.   The visual inspection apparatus according to claim 2, wherein each of the reference image and the in-use image includes an image of an iris of the eyeball. A display optical system for guiding the light of the optotype presented by the display means to the retina of the eyeball;
An observation optical system for guiding the image of the eyeball to the image sensor;
Have
The display optical system has a mirror that reflects light of a specific wavelength and transmits other light on the eyeball side of the display element,
The optical axis from the pupil of the eyeball of the display optical system to the mirror matches the optical axis from the pupil of the eyeball of the observation optical system to the mirror. The visual inspection device described in 1. A method for correcting a target of a head-mounted visual inspection apparatus to be mounted on a subject's head,
Detecting the rotation of the eyeball associated with the tilt of the head of the subject in the left-right direction based on an image of the eyeball;
Correcting the presentation position of the visual target to be presented to the eyeball of the subject according to the rotation of the eyeball;
A method of correcting a target of a visual inspection apparatus having The step of detecting the rotation of the eyeball comprises:
A reference image holding step for holding an image of the eyeball imaged when the head of the subject is in a reference state as a reference image;
An in-use image acquisition step of acquiring an in-use image that is an image of the eyeball imaged when the subject is in use; and
Pattern-matching the in-use image with the reference image and measuring a rotation angle of the in-use image with respect to the reference image;
Have
In the target correction step,
The visual target correction method of the visual inspection apparatus according to claim 5, wherein the display position of the visual target presented by the display unit is corrected according to the rotation angle. A head-mounted display device mounted on a user's head,
Display means for displaying an image on the eyeball of the user;
Imaging means for imaging the eyeball;
Based on the image of the eyeball imaged by the imaging means, rotation detection means for detecting the rotation of the eyeball accompanying the tilt of the head of the subject in the left-right direction;
Image correcting means for correcting the display position of the image displayed by the display means in accordance with the rotation of the eyeball;
A display device.