JP2011050479A - Visual function measuring device and visual function training device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the visual function of a subject when a visual target is moving by a small-sized device while keeping the size of the visual target on a retina fixed with a small number of components. <P>SOLUTION: In the state of presenting the virtual image of the image of an image display 1 through a half mirror 3 to the subject P turning to the direction of a concave mirror 2, by moving the image display 1 back and forth in the vertical direction by a moving device 4, the virtual image is moved back and forth. In the measuring device 6, while the virtual image is moved back and forth, an imaging part 61 picks up the image of the eye of the subject P to which the virtual image is presented at every preset measurement timing, and an operation part 62 calculates a pupil diameter (a feature amount relating to the eye of the subject P) from the picked-up image. A position detection part 5 detects the position of the virtual image at each measurement timing by detecting the position of the image display 1 at every measurement timing. A determination part 7 determines the state of the visual function of the subject P using relation between the pupil diameter and the position of the virtual image at each measurement timing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a visual function measuring device that presents a visual target to a subject and measures the visual function of the subject, and a visual function training device using the same.

  In recent years, with the advancement of information technology, work using a visual terminal device (for example, a monitor of a personal computer) (hereinafter referred to as “VDT work”) is increasing. This advance in information technology can greatly improve the efficiency and accuracy of work.

  However, in the VDT work, since the worker keeps looking at the visual terminal device at a short distance for a long time, the visual function of the worker is fatigued. Similar visual function fatigue also occurs when a television monitor is viewed for a long time. Visual functions include a focus adjustment function, pupil response, and convergence. The focus adjustment function refers to a function that always forms an image on the retina by changing the refractive power of the lens according to the distance between the lens and the target. Pupil reaction refers to adjusting the pupil in response to a stimulus such as a change in the amount of light. Convergence means that when looking at a nearby object, the eye muscles are placed inward (nose side) so that the line of sight is in close focus. As a typical example of visual function fatigue, fatigue of a focus adjustment function represented by adjustment convulsions can be mentioned. When the operator gazes at the display screen of the visual terminal device or the television monitor at a short distance, the ciliary muscle that is the driving source of the focus adjustment function is in a tension state. The fatigue of the focus adjustment function is caused by the persistence of the tension of the focus adjustment function as a result of working at a short distance for a long time. When fatigue of the focus adjustment function (eye strain) associated with work at a short distance occurs, the refractive power of the lens increases and myopia occurs, as well as a decrease in adjustment speed and a delay in adjustment time associated with focus adjustment.

  By the way, conventionally, a focus adjustment function measuring device for measuring a focus adjustment function of an operator (subject) by a method as described below is known (see, for example, Patent Document 1). Conventional focus adjustment function measuring devices are equipped with a lens system that changes the presentation position (viewing distance) of the visual target, and presents the static visual target to the subject at each different presentation position to continuously change the refractive power of the crystalline lens. Thus, the focus adjustment function of the subject at each presentation position is measured by obtaining the appearance frequency of a predetermined high-frequency component (high-frequency component of fine adjustment) from the temporal change in refractive power at each presentation position.

  Conventionally, a visual acuity measuring apparatus that measures a visual acuity of a subject by moving a display device that is a visual target is known (see, for example, Patent Document 2).

JP 2005-296310 A JP 2006-263067 A

  By the way, an apparatus using a lens system as an optical system tends to increase the number of optical components for constituting the optical system. Therefore, since the focus adjustment function measuring apparatus of Patent Document 1 uses a lens system for generating a visual target, a focusing lens, a measurement target plate, a projection lens, a beam splitter, an objective lens, and the like are required. There was a problem that the number of parts increased.

  On the other hand, in the visual acuity measuring device of Patent Document 2, since the object (display device) itself serving as a target is moved, there is a problem that the entire device becomes larger as the moving distance of the target is increased. When the object itself is a target, the size of the target on the retina usually changes according to the viewing distance. For this reason, in the visual acuity measuring apparatus of Patent Document 2, it is necessary to further add an optical component for making the size of the visual target on the retina constant even when the visual distance changes.

  The present invention has been made in view of the above points, and an object of the present invention is to measure the visual function of a subject when the target is moving, and to keep the size of the target on the retina constant with a small number of parts. Another object of the present invention is to provide a visual function measuring device that can be realized with a small device while maintaining the same, and a visual function training device using the same.

  The invention of a visual function measuring device according to claim 1 is a visual function measuring device that presents a visual target to a subject and measures the visual function of the subject, and an optical distance to an object for generating the visual target Between the concave mirror and the object within a range shorter than the focal length of the concave mirror so that the virtual image reciprocates. A moving means for changing an optical distance; a position detecting means for detecting the position of the virtual image when the optical distance is changed by the moving means; and the optical distance when the optical distance is changed by the moving means. The virtual image reciprocates from the relationship between the feature quantity measuring means for measuring the feature quantity relating to the eye of the subject, the virtual image position detected by the position detection means, and the feature quantity measured by the feature quantity measurement means. Characterized in that it comprises a determination means for determining the state of the visual function of time.

  According to a second aspect of the present invention, there is provided the visual function measuring device according to the first aspect, wherein the feature amount measuring means uses an imaging unit that images the eyes of the subject and the captured image of the imaging unit. And an arithmetic unit for calculating

  According to a third aspect of the present invention, there is provided the visual function measuring device according to the second aspect, wherein the calculation unit calculates the pupil diameter of the subject as the feature amount from the captured image.

  According to a fourth aspect of the present invention, there is provided the visual function measuring device according to the second aspect, wherein the calculation unit calculates the refractive power of the crystalline lens of the subject as the feature amount from the captured image.

  The invention of a visual function training device according to a fifth aspect includes the visual function measuring device according to any one of the first to fourth aspects, wherein the moving means follows a change in the feature amount following a change in the position of the virtual image. As described above, the moving condition of the virtual image is adjusted by changing the change condition of the optical distance.

  According to the first aspect of the present invention, by using the virtual image formed by the concave mirror as the target, the target can be moved greatly even if the change in the optical distance between the object and the concave mirror is small. That is, according to the first aspect of the present invention, when the target is moved by a predetermined distance, the entire apparatus is compared with a case where the target is moved without using a concave mirror (for example, when a lens system is used). It can be downsized.

  According to the first aspect of the present invention, since the virtual image formed by the concave mirror is used as a target, the virtual image is enlarged as the image is formed farther, so that the angle of view is made constant regardless of the viewing distance. Can do. As a result, since the size of the target on the retina can be kept constant even when the viewing distance changes, it is possible to make it difficult for the subject to notice the movement of the target. In other words, the target on the retina can be made the same size and presented to the subject regardless of whether the target is at a position far from the subject or near.

  Furthermore, according to the first aspect of the present invention, the number of optical components can be reduced by using a concave mirror for generating a target as compared with the case of using a lens system.

  According to the first aspect of the present invention, the relationship between the position of the virtual image and the feature amount related to the eye of the subject while changing the optical distance between the object and the concave mirror and reciprocating the target is presented to the subject. By determining the state of the visual function of the subject, the dynamic visual function of the subject when the target is moving can be measured.

  According to invention of Claim 2, the said feature-value can be easily measured by calculating the feature-value regarding a test subject's eye using the captured image by which the test subject's eye was imaged.

  According to the third aspect of the present invention, by calculating the pupil diameter of the subject as a feature amount related to the subject's eye from the captured image, it is possible to determine the state of miosis that occurs when the viewing distance is short. The state of the visual function of the subject can be determined using the pupillary reaction in which is noticeable.

  According to the invention of claim 4, the state of the visual function of the subject can be accurately determined by measuring the refractive power of the subject's crystalline lens as a feature quantity relating to the subject's eye from the captured image.

  According to the fifth aspect of the present invention, by changing the change condition of the optical distance between the object and the concave mirror so that the change of the feature amount follows the change of the position of the virtual image, the eye of the subject with respect to the movement of the virtual image is changed. Since the moving state of the virtual image can be adjusted so that the feature amount related to can be immediately responded, it is possible to effectively train the visual function of the subject.

It is an external view which shows the structure of the visual function measuring device which concerns on Embodiment 1. FIG. It is a figure which shows the principle of a concave mirror. It is a figure which shows the captured image of the eyeball in the visual function measuring device which concerns on the same as the above. It is a figure explaining the principle which measures the refractive power of a test subject's crystalline lens in the visual function measuring device which concerns on Embodiment 2. FIG. It is an external view which shows the structure of the visual function measuring device which concerns on Embodiment 4. FIG. It is an exploded view which shows the structure of the visual function measuring device which concerns on the same as the above.

(Embodiment 1)
Embodiment 1 demonstrates the visual function measuring apparatus which presents a test subject to a test subject and measures a test subject's visual function. As shown in FIG. 1, the visual function measuring device according to the present embodiment includes an image display device 1 that displays an image, and a concave mirror 2 that is provided so that the optical distance between the image display device 1 and the focal length is shorter than the focal length. The half mirror 3 provided obliquely to the optical axis Lx of the concave mirror 2 that passes through the observation point that is the observation position of the subject P, the moving device 4 that moves the image display device 1, and the virtual image B (see FIG. 2) A position detecting unit 5 that detects the position of the subject P, a measuring device 6 that measures a characteristic amount related to the eye of the subject P, and a determination unit 7 that determines the state of the visual function of the subject P.

  Usually, the subject P has miosis when the viewing distance is short. This is called near-field reflection or near-miosis. Therefore, in the visual function measuring device of this embodiment, the state of visual function is determined by determining the state of miosis.

  The image display device 1 is a small flat panel display such as a liquid crystal panel or an organic electro-luminescence display, and displays an image on the image display surface 10. The image content displayed on the image display surface 10 is not particularly limited, and may be content according to the preference of the subject P, such as a document, a still image (photo, picture), a moving image (video), or a game. The image display device 1 can easily control display image switching, image processing, and the like. The image display device 1 is a device for generating a visual target and corresponds to the object of the present invention.

  During the measurement of the visual function of the subject P, which will be described later, the image display device 1 presents an optical distance (relative position relative to the concave mirror 2) to the concave mirror 2 in order to present a virtual image B with a certain brightness to the subject P. ), The brightness of the display image can be changed. Further, the image display device 1 can change the brightness of the display image according to the preference of the subject P.

  The concave mirror 2 reflects the image displayed on the image display device 1 and presents the virtual image B (see FIG. 2) of the image to the subject P via the half mirror 3 as a target. The observation point which is the observation position of the subject P is located in front of the concave mirror 2 (left side in FIG. 1).

  The half mirror 3 is provided so as to intersect the optical axis Lx of the concave mirror 2 at an angle of 45 °. An image from the image display device 1 is reflected by the half mirror 3 toward the concave mirror 2 in the direction of the optical axis Lx of the concave mirror 2. The virtual image B of the image is presented to the subject P through the half mirror 3.

  With the arrangement of the image display device 1, the concave mirror 2, and the half mirror 3 as described above, an image from the image display device 1 is reflected on the concave mirror 2 side of the half mirror 3 and projected onto the concave mirror 2, and the half mirror 3 passes through the half mirror 3. The subject P can visually recognize the virtual image B of the image. Thus, unlike the structure in which the image display device 1 is provided between the subject P who watches the virtual image B and the concave mirror 2, the image display device 1 does not block the line of sight of the subject P.

  The moving device 4 is a moving mechanism of the image display device 1, and includes a holding plate 40, a linear guide 41, a feed screw 42, a pulley 43 a and a pulley belt 43 b, a motor 44, and a control unit 45. . The moving device 4 corresponds to the moving means of the present invention.

  The image display device 1 is held on the holding plate 40. The linear guide 41 supports the holding plate 40. The motor 44 is an electronic motor serving as a drive source for the moving device 4. The pulley 43 a and the pulley belt 43 b transmit the rotational driving force of the motor 44 to the feed screw 42. The control unit 45 controls the motor 44.

  The rotational driving force generated by the motor 44 under the control of the control unit 45 is transmitted to the feed screw 42 via the pulley 43a and the pulley belt 43b. In the feed screw 42, the rotational motion is converted into a linear motion, and the holding plate 40 and the image display device 1 move in the vertical direction (the arrow direction in FIG. 1). That is, the moving device 4 moves the holding plate 40 and the image display device 1 by the control unit 45 controlling the motor 44. At this time, the control unit 45 reciprocates the image display device 1 in the vertical direction so that the optical distance between the image display device 1 and the concave mirror 2 changes within a range shorter than the focal length of the concave mirror 2. Thereby, the virtual image B (refer FIG. 2) can be reciprocated. Further, the control unit 45 can freely set the moving speed of the image display device 1 by controlling the rotational speed of the motor 44. Thereby, the image display apparatus 1 can be moved at a speed according to a moving speed law adapted to the physiological aspect of the eye of the subject P.

Next, the principle of image display using the concave mirror 2 will be described with reference to FIG. F is the focal position of the concave mirror 2. When the object A that is a real image (the image display device 1 in the present embodiment) is on the concave mirror 2 side from the focal position F of the concave mirror 2, the image formed on the concave mirror 2 is an erecting virtual image represented by B. The distance b between the concave mirror 2 and the virtual image B is given by the distance a between the concave mirror 2 and the object A and the focal length f.
b = a * f / (af) (1)
It is expressed as Further, the size B ₁ B ₂ of the virtual image B is given by A ₁ A ₂ as the size of the object A.
B ₁ B ₂ = A ₁ A ₂ × | f | / | af− (2)
It becomes.

  In the visual function measuring device of this embodiment, the virtual image B formed when the object A is moved within the range between the center point O of the concave mirror 2 and the focal position F is an observation target. Thereby, a large movement of the virtual image B to be observed can be realized with respect to a small movement of the object A. As an example in which the visual function measuring device can be implemented, for example, when the concave mirror 2 having a spherical surface with a curvature radius of 300 mm and f = 150 mm is used, b = −0.3 m when a = 100 mm, and a = 148 mm. When b = -11.0 m. The virtual image B can realize a very large movement compared to the movement of the object A. That is, a large movement of the virtual image B to be observed can be realized by a small movement of the object A.

  Further, as the object A approaches the focal position F and the virtual image B approaches the far point, the enlargement ratio of the virtual image B with respect to the object A increases. As a result, even if the distance b changes, the size of the virtual image B on the retina of the observer's eye becomes almost constant.

  As described above, in the visual function measuring device using the concave mirror 2, the focus adjustment function of the eye of the observer gazing at the virtual image B of the object A is stimulated by continuously changing the distance a between the object A and the concave mirror 2. Can continue to give.

  In the present embodiment, when the moving device 4 moves the image display device 1 up and down, the distance between the image on the image display surface 10 of the image display device 1 and the optical axis Lx of the concave mirror 2 changes, and the image The optical distance between the display device 1 and the concave mirror 2 changes. When the optical distance changes, the distance between the concave mirror 2 and the virtual image B also changes.

  The position detection unit 5 is configured by a computer, and when the optical distance between the image display device 1 and the concave mirror 2 is changed by the moving device 4, a virtual image B (see FIG. 2) at every preset measurement timing. ) Position is detected. In the present embodiment, the position of the virtual image B is detected by acquiring movement control information of the image display device 1 by the control unit 45. The position detector 5 corresponds to the position detector of the present invention.

  The measuring device 6 includes a light source 60, an imaging unit 61, and a calculation unit 62. When the optical distance between the image display device 1 and the concave mirror 2 is changed by the moving device 4, a virtual image B (viewing The pupil diameter φ (see FIG. 3) of the subject P is measured as a feature amount related to the eye of the subject P on which the mark is presented. The measuring device 6 corresponds to the feature amount measuring means of the present invention.

  The light source 60 is an infrared light emitting diode, and emits infrared light to the eyeball of the subject P when DC power is supplied from a DC power source (not shown). The infrared light reflected from the eyeball surface of the subject P is again reflected by the half mirror 3 and enters the imaging unit 61. In addition, the light source 60 is arrange | positioned so that the test subject's P visual field may not be disturbed. Moreover, since the light emission wavelength of the light source 60 is in the infrared wavelength region, the light from the light source 60 is not sensed by the subject P, and the anxiety of the subject P can be reduced.

  The imaging unit 61 is an infrared CCD camera that is sensitive to infrared rays. When DC power is supplied from a DC power source (not shown), infrared light from the light source 60 is irradiated on the eye of the subject P. While there, the subject's eyes are imaged at each measurement timing. The captured image 63 shown in FIG. 3 is a black and white grayscale image.

  The computing unit 62 shown in FIG. 1 is a computer on which image processing software is installed, and acquires a captured image 63 from the imaging unit 61 via video capture (not shown). The calculation unit 62 that has acquired the captured image 63 illustrated in FIG. 3 extracts the pixel value (luminance value) of each pixel in the scanning signal line along the horizontal direction in the captured image 63. In the subject P, the pupil is darker than the peripheral portions such as the iris and the white eye. Therefore, the pixel value of the portion corresponding to the pupil (hereinafter referred to as “pupil portion”) 630 in the captured image 63 is lower than the peripheral portion. ing. The computing unit 62 compares the pixel value of each pixel on the scanning signal line with a predetermined threshold value, and extracts a set of pixels whose pixel value is less than the threshold value. The calculation unit 62 performs the above-described processing from the upper end to the lower end of the captured image 63 for each captured image 63, and extracts a set of pixels whose pixel values are less than the threshold on each scanning signal line, whereby the pupil portion 630 is obtained, and the position of the pupil of the subject P and the pupil diameter φ (the size of the pupil) are obtained for each captured image 63.

  By the way, in the calculation part 62, the pupil part 630 is extracted by comparing the pixel value of each pixel on the scanning signal line with the threshold value. Therefore, the size of the pupil part 630 changes depending on the size of the threshold value.

  Therefore, the calculation unit 62 obtains the pupil diameter φ for each threshold while changing the threshold. From the relationship between the threshold and the pupil diameter φ, a threshold range in which the pupil diameter φ is constant is obtained. The calculation unit 62 sets a final threshold value from a threshold value range in which the pupil diameter φ is constant. The computing unit 62 determines the pupil portion 630 for each captured image 63 using the final threshold as described above.

  The threshold value may be set by a method other than that set by the calculation unit 62 as described above. For example, the operator may manually set the threshold value using the captured image 63 or the like.

  The determination unit 7 illustrated in FIG. 1 is configured by a computer, and acquires the position information of the virtual image B detected by the position detection unit 5 and the information on the pupil diameter φ of the subject P measured by the measurement device 6. The determination unit 7 determines the state of the visual function of the subject P by obtaining the change in the pupil diameter φ when the position of the virtual image B is changed from the relationship between the acquired position information of the virtual image B and information on the pupil diameter φ. To do. The determination unit 7 corresponds to the determination unit of the present invention.

  Next, the moving range of the virtual image B will be described. From the equation (1) indicating the positional relationship between the real image (image display device 1) and the virtual image B, the virtual image B rapidly moves to infinity as the image display device 1 approaches the focal position. The closest point that can be clearly seen by the subject P in his 20s, that is, the adjustment near point, is said to be an average of 0.118 m (about 8.5 diopters). Accordingly, it is sufficient that the closest position (nearest position) is a position where the distance from the subject P is about −0.1 m. The nearest position is also a reasonable value from the viewpoint of interference between the image display device 1 and the half mirror 3. On the other hand, the farthest position (farthest position) may be a position where the distance from the subject P is about −10 m (−0.1 D). The control unit 45 controls the motor 44 so as to move the image display device 1 within the movement range of the image display device 1 set so as to realize the farthest position and the latest position.

  Next, a method for using the visual function measuring device according to this embodiment will be described. First, the subject P faces the concave mirror 2 from the observation point (the direction of FIG. 1), and the virtual image B of the image of the image display device 1 is presented. Thereafter, the moving device 4 reciprocates the image display device 1 in the vertical direction, so that the virtual image B reciprocates. While the virtual image B is reciprocating, the imaging unit 61 captures the eyes of the subject P on which the virtual image B is presented at each preset measurement timing, and the calculation unit 62 captures the captured image 63 (see FIG. 3). The pupil diameter φ is calculated. The position detection unit 5 detects the position of the virtual image B at each measurement timing by detecting the position of the image display device 1 at each measurement timing. Subsequently, the determination unit 7 determines the state of the visual function of the subject P using the relationship between the pupil diameter φ and the position of the virtual image B at each measurement timing.

  As described above, according to the present embodiment, by using the virtual image B formed by the concave mirror 2 as a target, even if the change in the optical distance between the image display device 1 and the concave mirror 2 is small, the target is increased. Can be moved. That is, according to the present embodiment, when moving the target by a predetermined distance, the entire apparatus is made smaller than when moving the target without using the concave mirror 2 (for example, when using a lens system). Can be

  Further, according to the present embodiment, the virtual image B formed by the concave mirror 2 is used as a target, so that the virtual image B is enlarged as the image is formed farther, so that the angle of view is made constant regardless of the viewing distance. be able to. As a result, since the size of the target on the retina can be kept constant even when the viewing distance changes, it is possible to make it difficult for the subject P to notice the movement of the target. In other words, the target on the retina can be made the same size and presented to the subject P regardless of whether the target is at a position far from or near the subject P.

  Furthermore, according to this embodiment, the number of optical components can be reduced by using the concave mirror 2 for generating the visual target as compared with the case of using a lens system.

  Further, according to the present embodiment, the position of the virtual image B and the subject are changed while the virtual distance between the image display device 1 and the concave mirror 2 is changed and the virtual image B (target) is reciprocated and presented to the subject P. By determining the state of the visual function of the subject P from the relationship with the pupil diameter φ of P (the characteristic amount related to the eye of the subject P), the dynamic of the subject P when the virtual image B (target) is moving is determined. Visual function can be measured.

  Furthermore, according to the present embodiment, the feature amount is easily measured by calculating the pupil diameter φ (feature amount relating to the eye of the subject P) of the subject P using the captured image 63 obtained by capturing the eye of the subject P. can do. At this time, according to the present embodiment, the pupil diameter φ of the subject P is calculated from the captured image 63 as the feature amount related to the eye of the subject P, thereby determining the miosis state that occurs when the viewing distance is short. Therefore, the state of the visual function of the subject P can be determined using the pupillary reaction in which eye strain appears significantly.

  Note that the visual function measurement device of the present embodiment uses the image display device 1 as an object. However, as a modification of the visual function measurement device, a solid object may be used instead of the image display device 1 as an object. Good. In this case, the three-dimensional object can be moved by being directly or indirectly attached to the holding plate 40. Even in a configuration using such a three-dimensional object as an object, the same operation as that of the present embodiment can be performed, and as a result, the same effect as that of this embodiment can be obtained. The same applies to the following second to fifth embodiments.

  In order to change the optical distance between the image display device 1 and the concave mirror 2, only the image display device 1 is moved, only the concave mirror 2 is moved, and both the image display device 1 and the concave mirror 2 are moved. There are three methods. The visual function measuring device of this embodiment includes a moving device 4 that moves only the image display device 1 as a moving unit. As a modification of this visual function measuring device, instead of the moving device 4 or a moving device. 4, a concave mirror moving device that moves the concave mirror 2 in the direction of the optical axis Lx may be provided as a moving means. This visual function measuring device can move the virtual image B by moving the concave mirror 2. However, in order for the subject P to correctly observe the virtual image B, the position of the eye of the subject P with respect to the concave mirror 2 is limited to a certain range. For this reason, when the concave mirror 2 is moved, the position of the eye of the subject P also needs to be moved. Therefore, among the three methods described above, the method of moving only the image display device 1 is the best and practical. That is, as the moving means, the moving device 4 of this embodiment is superior to the concave mirror moving device in that it is not necessary to move the position of the eye of the subject P, and is realistic. The same applies to the following second to fifth embodiments.

(Embodiment 2)
The visual function measuring device according to the second embodiment is implemented in that the refractive power (thickness) of the crystalline lens of the subject P is measured instead of measuring the pupil diameter φ of the subject P as the characteristic amount related to the eye of the subject P. This is different from the visual function measuring device according to the first aspect.

  The measuring device 6 of this embodiment measures the refractive power of the crystalline lens of the subject P using the principle of an autorefractometer. The light source 60 of this embodiment irradiates the eyeball P1 of the subject P with a pattern D as shown in FIG. The imaging unit 61 of the present embodiment is a camera that can capture an image of the eyeball P1 on the fundus P2 shown in FIG. The computing unit 62 of the present embodiment obtains the size of the image generated on the fundus P2 of the eyeball P1 shown in FIG. 4A from the captured image 63 captured by the imaging unit 61. The size of the image generated on the fundus P2 changes as shown in FIGS. 4B to 4D depending on the refractive power of the crystalline lens. Therefore, the calculation unit 62 can calculate the refractive power of the crystalline lens of the subject P from the obtained image size.

  The determination unit 7 of the present embodiment has the image shown in FIG. 4B when the virtual image B approaches from the far point, and the image shown in FIG. 4D when the virtual image B moves away from the far point. In this case, it is determined that the refractive power of the crystalline lens of the subject P is changing in the same manner as the movement of the virtual image B. On the other hand, when the virtual image B approaches from the far point, the image shown in FIG. 4D is obtained, or when the virtual image B moves away toward the far point, the image shown in FIG. 4B is obtained. If it is determined, the determination unit 7 determines that the refractive power of the crystalline lens of the subject P is different from the movement of the virtual image B. Thereby, the determination part 7 of this embodiment can determine the state of the visual function of the subject P.

  As described above, according to the present embodiment, the state of the visual function of the subject P can be accurately determined by measuring the refractive power of the crystalline lens of the subject P as the feature amount related to the eye of the subject P from the captured image 63.

(Embodiment 3)
The visual function measurement device according to the third embodiment is different from the visual function measurement device according to the second embodiment in that the refractive power of the crystalline lens of the subject P is measured using the principle of Purkinje image. Note that the light source 60 and the imaging unit 61 of the present embodiment are the same as those of the first embodiment.

  The operation of the visual function measuring device of this embodiment will be described. First, the incident light from the light source 60 to the eyeball is reflected on each of the cornea surface, the cornea back surface, the lens surface, and the lens back surface. Each of the reflected images is referred to as first to fourth Purkinje images. The first to fourth Purkinje images are detected from the captured image 63. Subsequently, the calculation unit 62 detects the positions of the first and fourth Purkinje images. Thereafter, the computing unit 62 calculates the refractive power of the light beam from the position of the light source 60, the position of the first Purkinje image, and the position of the fourth Purkinje image, and calculates the refractive power of the crystalline lens of the subject P. Can do.

  As described above, according to the present embodiment, the refractive power of the crystalline lens of the subject P can be easily measured from the captured image 63 as the feature amount related to the eye of the subject P.

  In addition, the visual function measuring device of Embodiment 2 calculates | requires the refractive power of the test subject's P lens using the principle of an autorefractometer, and the visual function measuring device of Embodiment 3 uses the principle of a Purkinje image. The refractive power of the P lens is obtained. However, the visual function measuring device is not limited to the above principle, and the refractive power may be obtained using another principle.

  In addition, as a characteristic amount related to the eye of the subject P, the visual function measuring device of the first embodiment measures the pupil diameter φ of the subject P, and the visual function measuring device of the second and third embodiments measures the refractive power of the crystalline lens of the subject P. However, as a modification of the first to third embodiments, the visual function measuring device may measure the line of sight (convergence) of the subject P as the feature amount in addition to the pupil diameter φ and the refractive power of the crystalline lens. In the case of the above modification, the calculation unit 62 uses the center position of the pupil in the captured image and the position of the Purkinje image (reflected light on the corneal surface when the eyeball is irradiated with infrared light), and the line of sight of the subject P Measure. The same applies to the following fourth and fifth embodiments.

  Furthermore, as a modification of the first to third embodiments, the visual function measuring device may measure the intraocular pressure of the subject P as the feature amount related to the eye of the subject P, or may measure the area or the center of gravity of the pupil. Good. The same applies to the following fourth and fifth embodiments.

  Moreover, as a modification of the first to third embodiments, the visual function measuring device may measure a plurality of items as the feature amount related to the eye of the subject P. In particular, when the pupil diameter φ and the refractive power of the crystalline lens are measured as the feature quantities, the measuring device 6 uses the method of the first embodiment from one captured image 63 captured by the imaging unit 61 that is an infrared CCD camera. The pupil diameter φ is measured, and the refractive power of the crystalline lens can be measured by the method of the third embodiment. The same applies to the following fourth and fifth embodiments.

(Embodiment 4)
The visual function measuring device according to the fourth embodiment is designed so that the subject P can easily measure the visual function as shown in FIGS. 5 and 6 as compared with the visual function measuring device according to the first embodiment (see FIG. 1). It is a structured.

  As shown in FIG. 6, the visual function measuring device of the present embodiment includes an image display device 1, a concave mirror 2, a half mirror 3, a moving device 4, a position detecting unit 5, a measuring device 6, and a determining unit. 7 in the same manner as the visual function measuring device of the first embodiment. Furthermore, the visual function measuring device of the present embodiment includes a housing 80, a base 81, struts 82 and 83, a head fixing member 84, a light shielding cover 85, a gripping portion 86, a microphone 87, and a switch. 88.

  The housing 80 accommodates the image display device 1, the concave mirror 2, and the half mirror 3. An opening 801 is formed on the front surface 800 of the housing 80 facing the subject P so that the subject P can be presented with the virtual image B projected on the concave mirror 2.

  The base 81 and the columns 82 and 83 are provided to fix and use the visual function measuring device. A casing 80 is attached to the support 82 when the left eye of the subject P is the eye to be examined. A housing 80 is attached to the support 83 when the right eye of the subject P is the eye to be examined. The support columns 82 and 83 are provided with attachment portions to which the housing 80 is attached. The attachment portion is provided so that the casing 80 can move in the vertical direction of the columns 82 and 83, and is adjusted so that the position of the casing 80 matches the position of the eye of the subject P. Thereby, even if there are individual differences such as the size of the face of the subject P and the position of the eyes, the virtual image B can be presented to any subject P without blurring.

  The head fixing member 84 includes a chin rest 840 for placing the chin of the subject P and a fixing plate 841 for fixing the subject P against the forehead, and aligns the line of sight of the subject P on the optical axis of the concave mirror 2. Therefore, the positional relationship between the eye of the subject P and the concave mirror 2 is fixed. Thereby, the virtual image B (refer FIG. 2) can be shown with respect to the test subject P without blurring. The head fixing member 84 may further include a fixture (not shown) that fixes the position of the ear of the subject P.

  In the case of the one eye type, the light shielding cover 85 is provided so that external light does not enter the non-test eye (the right eye in FIG. 6). Thereby, the test subject P can be concentrated on the measurement of the state of visual function by the test eye (left eye in FIG. 6).

  The grip portion 86 is provided so as to protrude downward from the housing 80. When the subject P has the grip portion 86, the visual function measuring device can be used by hand. Thereby, the subject P can measure the state of visual function in a free posture.

  The microphone 87 and the switch 88 are reaction acquisition means for acquiring the response of the subject P. The microphone 87 and the switch 88 are used when the determination unit 7 determines the state of the visual function of the subject P using the subjective symptoms of the subject P. The subject P answers the intention of “I can see the target” or “I can't see the target” via the microphone 87 or the switch 88.

  The control unit 45, the position detection unit 5, the calculation unit 62, and the determination unit 7 of the present embodiment are configured by the same computer C. The computer C controls the light emission state of the light source 60. Further, a signal from the microphone 87 or the switch 88 is input to the computer C.

  Next, a method for using the visual function measuring device according to this embodiment will be described. First, the subject P places his chin on the chin rest 840 and fixes the forehead against the fixing plate 841. The non-examined eye is covered with a light shielding cover 85. Subsequently, the image display device 1, the concave mirror 2, and the half mirror 3 are aligned with the eye position of the subject P by the attachment portions of the support columns 82 and 83.

  Thereafter, the moving device 4 reciprocates the image display device 1 so that the virtual image B reciprocates. While the virtual image B is reciprocating, the imaging unit 61 captures the eyes of the subject P on which the virtual image B is presented at each preset measurement timing, and the calculation unit 62 captures the captured image 63 (see FIG. 3). The pupil diameter φ is calculated. The position detection unit 5 detects the position of the virtual image B at each measurement timing by detecting the position of the image display device 1 at each measurement timing. Subsequently, the determination unit 7 determines the state of the visual function of the subject P using the relationship between the pupil diameter φ and the position of the virtual image B at each measurement timing. The determination unit 7 can also use the reaction of the subject P acquired from the microphone 87 or the switch 88 when determining the state of the visual function of the subject P.

  As described above, according to the present embodiment, the visual function measuring device can set an optimal measurement environment for each subject P, so that the state of the visual function of the subject P can be determined more accurately and easily.

(Embodiment 5)
In the fifth embodiment, a visual function training device using the visual function measuring device according to the first embodiment will be described. As shown in FIG. 1, the visual function training device according to the present embodiment includes an image display device 1, a concave mirror 2, a half mirror 3, a moving device 4, a position detection unit 5, a measuring device 6, and a determination. Part 7.

  In the visual function training device according to the present embodiment, when the determination unit 7 determines the state of the visual function, whether or not the change in the pupil diameter φ (the feature amount related to the eye) follows the position change of the virtual image B. Determine.

  The moving device 4 of the present embodiment uses the determination result of the determination unit 7 to determine the optical distance between the image display device 1 and the concave mirror 2 so that the change in the pupil diameter φ follows the position change of the virtual image B. The moving condition of the virtual image B is adjusted by changing the changing condition. The change condition is at least one of a change speed and a change range of the optical distance. Specifically, the moving device 4 changes at least one of the moving speed and moving range of the image display device 1 to adjust at least one of the moving speed and moving range of the virtual image B.

  When the change in the pupil diameter φ does not follow the position change of the virtual image B, the determination unit 7 determines that the visual function of the subject P does not follow (delays) the moving speed of the virtual image B, for example. In this case, the moving device 4 moves the virtual image B by lowering the moving speed of the image processing device 1 by lowering the changing speed of the optical distance between the image display device 1 and the concave mirror 2 compared to the current state. Slow down. Thereby, since it can be set as the moving speed of the virtual image B suitable for the test subject's P visual function, visual function training can be performed effectively. In addition, the moving device 4 slows down the moving speed of the virtual image B as described above, and narrows the moving range of the image processing device 1 to change the optical distance change range between the image display device 1 and the concave mirror 2. To reduce the moving range of the virtual image B. The change speed of the optical distance and the change amount of the change range (including the case where the change amount is 0) are, for example, selection means (not shown) such as a selection switch and a selection button provided in the visual function training apparatus of this embodiment. 2) is appropriately selected according to the purpose by the subject P or the examiner. That is, the amount of change is appropriately selected according to the response of the subject P, the judgment of the examiner, the measurement result of the visual function so far, and the like.

  Next, the moving speed of the image display device 1 under the control of the control unit 45 in the present embodiment will be described. When the crystalline lens of the eye of the subject P is approximated to a thin convex lens, the distance between the center point of the crystalline lens and the virtual image B is short and far, even if the moving distance of the virtual image B is the same. In the case of, the change in the refractive power of the lens is greatly affected, and in the case of a long distance, the change in the refractive power of the lens is small. In other words, if it is desired to obtain the same change in refractive power, it is necessary to increase the time change of the moving distance of the virtual image B as the distance increases. In order to increase the time change of the moving distance of the virtual image B as the distance increases, the moving speed of the image display apparatus 1 is increased as the optical distance between the image display apparatus 1 and the concave mirror 2 increases. That's fine. Therefore, the control unit 45 controls the operation of the motor 44 so as to increase the moving speed of the image display device 1 as the optical distance between the image display device 1 and the concave mirror 2 increases. By moving the image display apparatus 1 as described above, the moving speed of the virtual image B can be effectively increased as the distance from the crystalline lens is increased, so that fatigue of the focus adjustment function of the eye can be reduced.

  Further, the control unit 45 periodically and continuously moves the image display device 1 between the concave mirror 2 and the focal position of the concave mirror 2 to repeat the reciprocating motion of the image display device 1. To control. By repeating the reciprocating motion of the image display device 1 in this way, the refractive power of the crystalline lens of the subject P can be effectively changed, so that the fatigue of the eye focus adjustment function can be further reduced. In particular, since the virtual image B can be gradually moved by moving the image display device 1 continuously, the movement of the virtual image B can be prevented from being noticed by the subject P.

  Also in the present embodiment, as in the first embodiment, it is sufficient that the nearest position is a position where the distance from the subject P is about −0.1 m. The nearest position is also a reasonable value from the viewpoint of interference between the image display device 1 and the half mirror 3. On the other hand, the farthest position may be a position where the distance from the subject P is about −10 m (−0.1 D). The distance range between the image and the subject P is a range in which a fatigue prevention effect for the focus adjustment function of the eye can be sufficiently obtained.

  As described above, according to the present embodiment, the change condition of the optical distance between the image display device 1 and the concave mirror 2 (the change of the image display device 1) so that the change of the pupil diameter φ of the subject P follows the position change of the virtual image B. By changing the moving speed and moving range), the moving state (moving speed and moving range) of the virtual image B can be adjusted so that the pupil diameter φ of the subject P can immediately respond to the movement of the virtual image B. The visual function training of the subject P can be effectively performed.

  As a modification of the present embodiment, the visual function training device may use the visual function measuring device according to the second and third embodiments. According to the above modification, the optical distance change condition between the image display device 1 and the concave mirror 2 (the moving speed of the image display device 1 or the like) so that the refractive power of the crystalline lens of the subject P follows the position change of the virtual image B. The movement state (movement speed and movement range) of the virtual image B can be adjusted so that the refractive power of the crystalline lens of the subject P can immediately respond to the movement of the virtual image B by changing the movement range). It is possible to effectively train the visual function of P.

  As a modification of the present embodiment, the visual function training device may use the visual function measuring device according to the fourth embodiment.

  Furthermore, as another example of using the visual function training device according to the present embodiment, a visual function training device is provided together with a visual terminal device for VDT work, and when the VDT work continues for a certain period of time or when the eyes are tired, The subject P may use the visual function training device of the present embodiment.

1 Image display device (object)
2 Concave mirror 3 Half mirror 4 Moving device (moving means)
5 Position detector (position detection means)
6 Measuring device (feature quantity measuring means)
61 Imaging unit 62 Calculation unit 7 Determination unit (determination means)
B Virtual image P Subject φ Pupil diameter

Claims (5)

A visual function measuring device that presents a visual target to a subject and measures the visual function of the subject,
A concave mirror provided so that an optical distance to an object for generating the target is shorter than a focal length, and a virtual image of the object as the target;
Moving means for changing the optical distance between the concave mirror and the object within a range shorter than the focal length of the concave mirror so that the virtual image reciprocates;
Position detecting means for detecting the position of the virtual image when the optical distance is changed by the moving means;
Feature quantity measuring means for measuring a feature quantity related to the eye of the subject when the optical distance is changed by the moving means;
Determination means for determining the state of the visual function when the virtual image is reciprocating from the relationship between the virtual image position detected by the position detection means and the feature quantity measured by the feature quantity measurement means. A visual function measuring device characterized by that. The feature amount measuring means includes:
An imaging unit for imaging the eyes of the subject;
The visual function measuring device according to claim 1, further comprising: an arithmetic unit that calculates the feature amount using a captured image of the imaging unit.   The visual function measuring device according to claim 2, wherein the calculation unit calculates a pupil diameter of the subject as the feature amount from the captured image.   The visual function measuring device according to claim 2, wherein the calculation unit calculates a refractive power of the crystalline lens of the subject as the feature amount from the captured image. The visual function measuring device according to any one of claims 1 to 4,
The visual function training device, wherein the moving means adjusts the moving state of the virtual image by changing the change condition of the optical distance so that the change of the feature amount follows the change of the position of the virtual image.

Images