HK1160755A - Target presentation device, image display system, and vehicle-mounted display device - Google Patents

Description

Optotype presenting device, image display system, and in-vehicle display device

Technical Field

The present invention relates to a visual target presenting device, an image display system, and an in-vehicle display device for presenting a visual target to an observer.

Background

In recent years, with the progress of information technology, operations using visual terminal devices (for example, displays of personal computers, etc.) (hereinafter, referred to as "VDT operations") have been increasing. With the progress of this information technology, the operation efficiency and the operation accuracy can be greatly improved.

However, prolonged VDT operation can cause eye fatigue to the operator. The same eye fatigue occurs even when a television display is viewed for a long time.

Next, the human eye will be explained. Fig. 16 shows the structure of a human eye. In order to image the light L emitted from the gazing object on the retina 64 sequentially through the cornea 60, pupil 61, crystalline lens 62, vitreous body 63, ciliary muscle (including zonules) 65 has a function of changing the thickness of the crystalline lens 62 to adjust the refractive power of the crystalline lens 62. This function is called a focus adjustment function. In other words, the focus adjusting function (focus adjusting mechanism) refers to a function (mechanism) of changing the refractive power of the lens 62 according to the distance between the lens 62 and the optotype, thereby always imaging an image on the retina 64.

In general, when an operator looks at a display screen of a visual terminal device or a television monitor at a short distance, ciliary muscles 65 as a drive source of a focus adjustment function are in a tense state. Abnormal excitation of parasympathetic nerves and the state of tension of the ciliary muscle 65 caused by the close focusing are one of the causes of eye fatigue. If the state of tension continues for a long time, the focal point regulating function of the ciliary muscle 65 temporarily decreases.

Therefore, japanese patent No. 3766681 (hereinafter referred to as "patent document 1") discloses an optotype presenting apparatus for promoting active movement of a focus adjusting function of an eye to restore eyesight. The visual target presentation device of patent document 1 is a device that activates the focus control function of the eyes of an observer by repeatedly moving a visual target in the distance direction on the line of sight of the observer who observes the visual target.

However, it is considered that a method of preventing eye fatigue, which continuously stimulates the focal point control function of the eyes through VDT operation or viewing behavior without doubt, is more preferable than a method of promoting the activity by stimulating the focal point control function of the eyes with fatigue, such as the visual target presentation device of patent document 1. Therefore, in consideration of introduction to a general VDT operation site or home, the optotype presenting apparatus is preferably small. In addition, in consideration of operability and visibility, an image needs to be larger than a predetermined size on the retina of an observer.

However, in the visual target display device of patent document 1, the entire length of the device is equal to the moving distance of the visual target. Thus, in order to provide the observer with a satisfactory effect for relieving eye fatigue, it is necessary to move the optotype on a scale of several meters. Therefore, the visual target display device of patent document 1 has a problem that the entire device becomes large. In addition, when an object displaying an image of a certain size moves, the size of the displayed image on the retina of the observer extremely changes depending on the position of the object. It is difficult to solve the above-described change in the size of the display image by a method such as a change in the display size of the image.

As a means for solving this problem, a visual target visualizing apparatus using a concave mirror is known (for example, see japanese patent application laid-open No. h 6-27411 (hereinafter referred to as "patent document 2")). The visual target display device displays a virtual image enlarged and imaged by the concave mirror to an observer as a visual target.

Fig. 17 shows the principle of image display using concave mirror 70. The mirror surface (reflection surface) of concave mirror 70 is a spherical surface. F is the focal position of concave mirror 70. When object a, which is a real image, is located closer to concave mirror 70 side (right side in fig. 17) than focal position F of concave mirror 70, the image formed by concave mirror 70 becomes an erect virtual image indicated by B. Distance B between concave mirror 70 and virtual image B is represented by distance a between concave mirror 70 and object a and focal distance f as:

b＝a×f/(a-f) (1)

when the size of the object A is defined as A₁A₂Size B of virtual image B₁B₂Comprises the following steps:

B₁B₂＝A₁A₂×|f|/|a-f| (2)

in the above-described visual target display device, the virtual image B formed when the object a is moved within the range between the center point O and the focal position F of the concave mirror 70 is set as the observation target. This enables the virtual image B to be observed to move significantly with respect to small movements of the object a, and thus enables the formation of a visual device for the purpose of preventing visual deterioration. As an example of the above-described visual target visualizing device, for example, in the case of using the concave mirror 70 formed of a spherical surface with f equal to 150mm and a curvature radius of 300mm, when a is equal to 100mm, b is equal to-0.3 m; when a is 148mm, b is-11.0 m. The virtual image B can achieve a very large movement compared to the movement of the object a. That is, a large movement of the virtual image B as the observation target can be achieved by a small movement of the object a. Thus, by changing the distance a between the object a and the concave mirror 70, the focus adjustment function of the eyes of the observer who looks at the virtual image B of the object can be stimulated.

In addition, as the object a approaches the focal position F and the virtual image B approaches the far point, the magnification of the virtual image B with respect to the object a becomes larger. As a result, even if the distance B changes, the size of the virtual image B on the retina of the observer's eye is almost constant.

As described above, in the visual target display device using concave mirror 70, the focal point adjustment function of the observer who observes virtual image B of object a can be continuously stimulated by continuously changing distance a between object a and concave mirror 70. As a result, in the visual target display device using concave mirror 70, fatigue of the focus adjusting function of the eyes can be alleviated by changing the optical distance between object a and concave mirror 70. In the visual target display device as described above, a system is employed in which the virtual image B is visually recognized with both eyes in view of the comfort of the observer.

However, when the object a and the concave mirror 70 are arranged as shown in fig. 17, there is a problem that the object a blocks the line of sight of the observer who views the virtual image B.

Fig. 18 shows an example of a method for solving this problem (see, for example, patent document 2, japanese patent application laid-open No. h 11-244239 (hereinafter referred to as "patent document 3") and japanese patent application laid-open No. 2000-171751 (hereinafter referred to as "patent document 4")). In fig. 18, a half mirror 71 that is oblique to the optical axis Lx of concave mirror 70 is provided between concave mirror 70 and observer P. When the light from object a is reflected in the optical axis direction of concave mirror 70 with half mirror 71 facing concave mirror 70, the light from object a is reflected by half mirror 71, and a virtual image of object a is formed by concave mirror 70. The observer P can observe a virtual image transmitted through the half mirror 71.

Patent document 2 discloses an apparatus using a concave mirror and a half mirror. The device of patent document 2 can improve the effect of a simulator by matching the imaging distance of a virtual image of a display object with the true distance of the display object in various simulators such as a flight simulator and a space docking simulator.

Patent document 3 discloses a small-sized vision measuring apparatus using the principle of concave mirrors for performing vision measurements at various visual distances. Patent document 4 discloses a head-mounted display in which the position of the optotype is moved back and forth, up and down, and right and left to prevent visual deterioration.

However, in the case of using the conventional visual target visualizing apparatus, the observer P is less required to change the refractive power of the crystalline lens as the virtual image as the visual target becomes farther away. Therefore, the ciliary muscle is always in a tense state, and the effect of relieving the fatigue of the focal-point regulating function is small.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a visual target presentation device, an image display system, and an in-vehicle display device that can sufficiently alleviate fatigue of an observer's focus adjustment function.

The visual target presenting device of the present invention presents a virtual image of an object to an observer as a visual target. The visual target display device comprises a concave mirror and a distance adjusting unit. The concave mirror is disposed such that an optical distance between the concave mirror and the object is shorter than a focal distance of the concave mirror, and is used to form the virtual image. The distance adjustment means is configured to change the optical distance in a range shorter than a focal distance of the concave mirror, and to increase a moving speed of the virtual image as the virtual image position is farther.

The object is, for example, an image display device that displays the image, a three-dimensional object, or the like. The image includes a moving image (video), a still image (photograph, drawing), and the like. The same applies to the following description.

According to this configuration, since the moving speed of the virtual image is faster as the virtual image position becomes farther, the temporal change in the lens refractive power of the observer can be made constant or more not only when the virtual image is located near the observation point but also when the virtual image is located far from the observation point. This can sufficiently relieve fatigue of the focus adjustment function of the observer.

Preferably, the visual target display device includes a half mirror provided obliquely to an optical axis of the concave mirror. The object is configured to be reflected on the concave mirror side of the half mirror and projected onto the concave mirror, and a virtual image of the object is visualized to the observer via the half mirror.

According to this configuration, since the optical axes of the half mirror and the concave mirror are oblique, when a virtual image as a visual target appears to an observer, it is possible to prevent the object itself from becoming an obstacle.

Preferably, the distance adjusting means moves the object.

According to this configuration, since the distance adjustment means moves the object, the virtual image of the object can be moved, and therefore, it is not necessary to change the positions of the eyes of the observer, compared to a case where the virtual image is moved by the movement of the concave mirror. That is, the observer can visually recognize the optotype at the same observation point.

Preferably, the distance adjusting means increases the moving speed of the object as the optical distance increases.

With this configuration, the moving speed of the virtual image can be increased as the virtual image is farther from the observation point.

Preferably, the observation point is located in front of the concave mirror, and the distance adjustment unit moves the object so that a temporal change of an inverse of a distance between the observation point and a virtual image of the object is constant.

According to this configuration, since the object is moved such that the temporal change of the reciprocal of the distance between the observation point and the virtual image of the object is constant, the moving speed of the virtual image can be made faster as the virtual image is farther from the observation point more effectively, and therefore, fatigue of the observer's focus adjustment function can be more alleviated.

Preferably, the distance adjusting means changes the optical distance so as to repeat the reciprocating motion of the optotype.

According to this configuration, since the optotype repeats the reciprocating motion, the refractive power of the lens of the observer can be effectively changed, and fatigue of the focus adjusting function of the observer can be further reduced.

Preferably, the distance adjusting means moves the optotype periodically.

According to this configuration, since the optotype reciprocates periodically, the refractive power of the crystalline lens of the observer can be changed more frequently, and fatigue of the focus adjusting function of the observer can be further reduced.

Preferably, the distance adjusting means continuously moves the optotype.

According to this configuration, since the optotype continuously moves, the virtual image of the object can be moved slowly, and the observer can be prevented from feeling the movement of the virtual image of the object.

Preferably, the visual target display device includes a flat panel display for displaying the object.

According to this configuration, since the flat panel display is provided as a device for displaying an image of an object, the configuration can be made optically superior to the curved panel.

Preferably, the visual target presenting device includes a reduction unit that reduces distortion of the virtual image.

According to this configuration, since distortion of the virtual image to be the optotype is reduced, it is possible to provide an effect of preventing fatigue of the eye focus adjusting function without the observer noticing distortion of the optotype.

Preferably, the reduction means is formed using the concave mirror, and a mirror surface of the concave mirror is formed to be aspherical so as to reduce distortion of the virtual image.

According to this configuration, since the mirror surface of the concave mirror is aspherical, the effect of reducing the distortion of the optotype can be improved regardless of whether the surface of the object is flat or curved.

Preferably, the concave mirror has a larger radius of curvature of the mirror surface as the mirror surface approaches the center portion of the mirror surface.

According to this configuration, the distortion of the optotype can be further reduced because the radius of curvature of the central portion of the mirror surface increases as the mirror surface approaches the concave mirror.

Preferably, when the viewer views the icon, the ratio of the radius of curvature of the mirror surface in the center portion to the radius of curvature of the mirror surface in the 2 nd direction orthogonal to the 1 st direction is larger in the 1 st direction connecting both eyes of the viewer.

According to this configuration, since the ratio of the radius of curvature of the central portion of the mirror surface to the radius of curvature of the end portion is larger in the 1 st direction connecting the both eyes of the observer than in the 2 nd direction orthogonal to the 1 st direction, the distortion of the 1 st direction visual target can be made smaller than the distortion of the 2 nd direction visual target, and therefore, it is possible to suppress the virtual image from being more distorted due to the parallax of the both eyes and to appear stereoscopic.

Preferably, the reduction unit is formed using the object, and a surface of the object is formed into a curved surface so as to reduce distortion of the virtual image.

According to this configuration, since the surface of the object is a curved surface, the effect of reducing the distortion of the optotype can be enhanced regardless of whether the mirror surface of the concave mirror is a spherical surface or an aspherical surface.

Preferably, the object protrudes toward the concave mirror.

According to this configuration, since the object projects toward the concave mirror side, the distortion of the optotype can be further reduced.

Preferably, the object is cylindrically curved, and when the sight is displayed to the observer, an axial direction of the object is orthogonal to a direction connecting both eyes of the observer.

According to this configuration, it is possible to reduce distortion of the virtual image particularly in a direction connecting both eyes of the observer when the object is projected onto the concave mirror, and thus it is possible to suppress a case where the virtual image is more distorted due to binocular parallax and appears stereoscopic.

Preferably, the visual target display device includes a flat panel display that displays an image, and the reduction unit is formed using the object, the object being an image displayed on the flat panel display, and the image being deformed in advance so as to reduce distortion of the virtual image when projected onto the concave mirror.

According to this configuration, since the image displayed on the flat panel is deformed in advance, the effect of reducing the distortion of the optotype can be enhanced regardless of whether the mirror surface of the concave mirror is spherical or aspherical.

An image display system according to the present invention includes the above-described optotype presenting apparatus and an image display apparatus for displaying an image. The visual target presenting device presents a virtual image of the image displayed by the image display device to the observer as the visual target.

The in-vehicle display device of the present invention includes the above-described visual target display device and an image display device that provides driving-related information. The visual target presenting device presents a virtual image of the information provided by the image display device to the observer as the visual target.

Preferably, the visual target presenting device includes a visual distance estimation device that estimates a visual distance of the observer, and the optical distance between the image display device and the concave mirror is changed such that the visual distance of the virtual image is increased when the visual distance of the observer is increased.

According to this configuration, the visual range in front of which the driver (observer) is looking at during driving is made to coincide with the visual range of the information relating to driving, and therefore fatigue associated with focus adjustment of the driver can be alleviated.

Drawings

Fig. 1 is an external view showing a configuration of a visual target presentation device according to embodiment 1.

Fig. 2 is a diagram for explaining the operation of the optotype presenting apparatus according to embodiment 1.

Fig. 3 is a diagram showing the moving speed of a virtual image in the visual target presenting apparatus according to embodiment 1.

Fig. 4 is a diagram showing another example of the moving speed of the virtual image in the visual target presenting apparatus according to embodiment 1.

Fig. 5 is a diagram showing design parameters of the visual target presenting apparatus according to embodiment 2.

Fig. 6A is a diagram illustrating imaging points of a virtual image of the optotype presenting apparatus according to embodiment 2.

Fig. 6B is a diagram showing a probability distribution of arbitrary x.

Fig. 7 is a diagram showing the shape of a virtual image of the visual target presentation device according to embodiment 2.

Fig. 8 is a diagram showing the shape of a virtual image of the visual target presentation device according to embodiment 3.

Fig. 9 is a diagram showing the shape of a virtual image of the visual target presentation device according to embodiment 4.

Fig. 10 is a diagram showing design parameters of the visual target presenting apparatus according to embodiment 5.

Fig. 11 is a diagram showing the shape of an image display device of the visual target presenting device according to embodiment 5.

Fig. 12 is a diagram showing the shape of a virtual image of the visual target presentation device according to embodiment 5.

Fig. 13 is a configuration diagram of embodiment 8.

Fig. 14 is an external view of embodiment 8.

Fig. 15A is a diagram of a case where a distant position is visually recognized in embodiment 9.

Fig. 15B is a diagram of a case where proximity is visually recognized in embodiment 9.

Fig. 16 is a cross-sectional view showing a structure of a human eyeball.

Fig. 17 is a diagram illustrating the principle of a concave mirror.

Fig. 18 is a diagram showing a configuration using a concave mirror and a half mirror.

Fig. 19 is a diagram illustrating a binocular single vision.

Fig. 20 is a diagram showing distortion of a virtual image in a conventional visual target presenting device.

Detailed Description

(embodiment mode 1)

First, the configuration of the optotype presenting apparatus according to embodiment 1 of the present invention will be described. Fig. 1 shows a configuration of a visual target presenting apparatus according to the present embodiment. As shown in fig. 1, the visual target display device includes an image display device (video display device) 1, a concave mirror 2, a half mirror 3, and a moving device 4. The image display apparatus 1 is configured to display an image (video) on an image display surface (video display surface) 10. The concave mirror 2 is disposed such that the optical distance between the image display device 1 and the concave mirror 2 is shorter than the focal distance. The half mirror 3 is disposed obliquely to the optical axis Lx of the concave mirror 2. The optical axis Lx of the concave mirror 2 passes through an observation position (hereinafter referred to as "observation point") of the observer P. The moving device 4 is configured to move the image display device 1. The visual target visualizing apparatus of the present embodiment visualizes a virtual image B (see fig. 17) imaged by the concave mirror 2 to an observer P as a visual target.

In order to reduce the distortion of the virtual image in the concave mirror 2, the image display surface 10 of the image display device 1 of the present embodiment is preferably a flat surface. Therefore, the image display device 1 of the present embodiment is a small-sized flat panel display such as a liquid crystal panel or an Organic Electro-Luminescence (hereinafter, referred to as "Organic EL") display. The image content displayed by the image display apparatus 1 is not particularly limited, and may be content suitable for the preference of the observer P, such as a file, a still picture (photograph, drawing), a moving picture (video), or a game. The image display apparatus 1 can easily control switching of a display image, image processing on the display image, and the like. Here, the image of the present embodiment corresponds to the object of the present invention.

Further, by providing the image display device 1 with a control device (not shown) that corrects distortion, brightness, or display size of an image corresponding to a virtual image position described later, it is possible to reduce the awareness of the observer P of moving the virtual image, and to concentrate the observer P on VDT operation or viewing behavior, as in the conventional VDT or television display.

In order for the image display device 1 to present a virtual image B of constant brightness to the observer P, the brightness of the display image can be changed in accordance with the optical distance between the image display device 1 and the concave mirror 2 (the relative position of the image display device 1 to the concave mirror 2). In addition, the image display apparatus 1 can change the brightness of the display image according to the preference of the observer P.

The concave mirror 2 is configured to reflect an image displayed by the image display device 1 and to visualize a virtual image B (see fig. 17) of the image as a target to an observer P via the half mirror 3. An observation point as an observation position of the observer P is located in front of the concave mirror 2 (left side in fig. 1).

The half mirror 3 is disposed to intersect the optical axis Lx of the concave mirror 2 at an angle of 45 °. An image displayed on 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. A virtual image B of the image appears to the observer 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 displayed by the image display device 1 is reflected on the concave mirror 2 side of the half mirror 3 and projected by the concave mirror 2, and the observer P can visually recognize the virtual image B of the image via the half mirror 3. Thus, unlike the structure in which the image display device 1 is provided between the observer P and the concave mirror 2, the image display device 1 does not block the line of sight of the observer P.

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

The image display device 1 is supported by the support plate 40. The linear guide 41 supports the support plate 40. The motor 44 is an electric motor serving as a drive source of the moving device 4. The pulley 43a and the pulley belt 43b transmit the rotational driving force of the motor 44 to the feed screw 42. The control unit 45 controls the motor 44. That is, the moving device 4 converts the rotational driving force generated by the motor 44 into a linear motion by the feed screw 42, thereby moving the image display device 1 in the vertical direction (the direction of the arrow in fig. 1). At this time, the control unit 45 moves 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 distance of the concave mirror 2. Further, the control unit 45 can freely set the moving speed of the image display device 1 by controlling the rotation speed of the motor 44. Thereby, the image display device 1 can be moved at a speed conforming to a movement speed rule or the like that is suitable for the physiology of the eyes of the observer P. The control unit 45 is, for example, a processing device of a computer. The computer may be a general-purpose computer such as a personal computer or may be a computer dedicated to the visual target display device.

When the image display device 1 is moved up and down by the moving device 4, 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 optical distance between the image display device 1 and the concave mirror 2 changes. When the optical distance is changed, the optical distance between the concave mirror 2 and the virtual image B is changed.

Next, the moving range of the virtual image B will be explained. As can be seen from equation (1) representing the positional relationship between the real image (image display device 1) and the virtual image B, the virtual image B moves rapidly to infinity as the image display device 1 approaches the focal position. In addition, it is generally considered that the closest point of sight, i.e., the accommodation near point, is clearly visible to an observer P in the age range of 20 years, which is an average of 0.118m (about 8.5 diopters). Therefore, if the distance between the observer P and the optotype is located at a position of about-0.1 m, the closest position (closest position) is sufficient. On the other hand, the farthest position (farthest position) may be located at a distance of about-10 m (-0.1D) between the observer P and the optotype. The distance range between the observer P and the optotype is a range in which the effect of preventing the eye focus adjustment function from being fatigued can be sufficiently obtained. The control unit 45 controls the motor 44 so that the image display device 1 moves within a movement range set to realize the farthest position and the closest position.

Next, the moving speed of the image display device 1 based on the control of the control unit 45 will be described. First, as shown in fig. 2, when the lens 5 of the eye of the observer P (see fig. 1) is approximated to a thin convex lens, assuming that the distance between the center point O of the lens 5 and the virtual image B (fixation point) as the observation point is s1 (< 0), the distance between the center point O of the lens 5 and the retina (imaging point) N is s2 (> 0), and the refractive power of the lens 5 expressed by diopter units is D:

1/s2＝1/s1+D (3)

the relationship of (1) holds.

The focal point regulating function of the eye means: by making the refractive power D of the lens 5 vary according to the distance s1 between the lens 5 and the virtual image B, the image is made to function as an image on the retina N at all times. As can be seen from equation (3), the larger the distance s1 between the lens 5 and the virtual image B, the smaller the degree of influence of the temporal change in the distance s1 between the lens 5 and the virtual image B on the temporal change in the refractive power D. That is, in the case where the distance s1 between the lens 5 and the virtual image B is short (in the case of a short distance) and long (in the case of a long distance), even if the moving distance of the virtual image B is the same, the influence on the refractive power change is large at the short distance and small at the long distance. In other words, in order to obtain the same degree of power change, it is necessary to increase the temporal change in the moving distance of the virtual image B as the distance increases. Since the distance s2 between the lens 5 and the retina N hardly changes, the diameter of the eyeball can be approximated to the diameter of the eyeballWhen the focal point regulating function of the eye is fully exerted, the formula (3) is used

To indicate.

Here, the stimulus given to the focal-point accommodation function of the eye is more than constant, which can be expressed alternatively as a temporal change in the refractive power D of the lens 5Always above a certain value. Therefore, in order to keep the stimulus given to the focal point adjusting function of the eye constant or more, the stimulus is obtained from the formula (4)

Where Γ represents a threshold.

According to the formula (5), the refractive power D is changed with timeThe value is always constant (threshold Γ), and the control unit 45 (see fig. 1) changes the distance s1 between the lens 5 and the virtual image B over time by the reciprocal 1/s1The motor 44 (see fig. 1) may be controlled so as to be constant, and the image display device 1 (see fig. 1) may be moved.

Specifically, according to the equation (5), the moving speed of the virtual image B needs to be increased as the distance s1 between the lens 5 and the virtual image B is longerThe faster, so that the time of the refractive power D varies even if the distance s1 between the lens 5 and the virtual image B variesAlso kept at a constant value (threshold Γ). In order to move the virtual image B at the target speed, the movement speed of the image display device 1 may be calculated with reference to equation (1). In this case, b in formula (1) is a distance s 1. The control part 45 controls the image display device 1 and the concave surfaceThe operation of the motor 44 is controlled so that the longer the optical distance between the mirrors 2, the faster the movement speed of the image display device 1. This enables the moving speed of the virtual image B to be set so as to be greater as the distance from the lens 5 serving as the observation point becomes longerThe further faster.

A specific example of the moving speed of the virtual image B of the image will be described. First, when in diopter units

Ds＝1/s1 (6)

When representing the distance s1 between the lens 5 and the virtual image B, equation (4) is expressed as:

according to equation (7), we obtain:

where Γ represents a threshold. When the tension of the ciliary muscle is changed, for example, at a constant speed, i.e., the time of the refractive power D of the lens 5 is changedWhen the value is set to a constant value, according to equation (8),is a constant value. This is in the moving speed rule of the present embodimentSimple and consistent with the physiological aspects of the movement speed associated with the focal point accommodation function of the eye. According to this rule, the control unit 45 (see fig. 1) controls the motor 44 (see fig. 1) to move the image display device 1 (see fig. 1). Fig. 3 shows a moving speed v of one cycle when the control unit 45 controls the motor 44 to move the distance s1 between the lens 5 and the virtual image B from 0.5m to 5.0m in a cycle of 120 seconds, for example. In the case of this rule, the buffering time T is provided because the movement speed v changes rapidly at the end point where the distance s1 between the lens 5 and the virtual image B is 5.0 m. The moving speed of the image display device 1 may be calculated using the moving speed v and equation (1).

By changing the time of reciprocal 1/s1 of the distance s1 between the lens 5 and the virtual image B as the observation point in this mannerSince the image display device 1 is moved in a constant manner, the moving speed of the virtual image B can be increased more effectively as the distance from the crystalline lens 5 as the observation point increases, and thus fatigue of the focus adjusting function of the observer P can be alleviated.

As another embodiment of the moving speed, a method of always keeping the absolute value of the moving speed of the image display device 1 constant may be considered. At this time, fig. 4 shows the moving speed v of one cycle when the distance s1 between the lens 5 and the virtual image B is moved from 0.5m to 5.0m at a cycle of 120 seconds, as described above. As described above, the buffer time T is provided in the portion where the sign of the moving speed v changes. The absolute value of the moving velocity v becomes larger as the distance s1 between the lens 5 and the virtual image B becomes longer, as in the case where the temporal change of diopter is constant, but the maximum value, the minimum value, and the like of the moving velocity v are different from the case where the temporal change of diopter is constant. The moving speed v shown in fig. 4 is also a speed that is suitable for the physiological aspect of the eye as described above, and has an advantage that the control related to the movement of the image display device 1 is simple.

The control unit 45 shown in fig. 1 controls the motor 44 so as to move the image display device 1 between the concave mirror 2 and the focal position of the concave mirror 2 periodically and continuously and repeat the reciprocating movement of the image display device 1. By repeating the reciprocating movement of the image display device 1 in this manner, the refractive power D of the lens 5 (see fig. 2) of the observer P can be effectively changed, and thus fatigue of the focus adjusting function of the observer P can be further reduced. Further, since the refractive power D of the lens 5 of the observer P can be changed more frequently by periodically performing the reciprocating movement of the image display device 1, fatigue of the focus adjusting function of the observer P can be further alleviated. Further, by continuously moving the image display device 1 and continuously moving the optical distance between the image display device 1 and the concave mirror 2, the virtual image B (see fig. 2) can be slowly moved, and therefore the observer P can be made unaware of the virtual image B.

Next, the operation of the visual target presenting device when the observer P uses the visual target presenting device according to the present embodiment will be described with reference to fig. 1. First, the observer P views a virtual image B (see fig. 2) of the image display device 1 in a direction (x direction in fig. 1) in which the observation point faces the concave mirror 2. When the control section 45 starts driving the motor 44, the image display device 1 starts moving in the upward direction. When the image display device 1 is moved to the upper limit position, the downward movement is started. Subsequently, when the image display device 1 is moved to the lower limit position, the upward direction movement is started. The image display device 1 repeats such an operation. During this period, the observer P keeps watching the virtual image B.

As another use example of the visual target presentation device according to the present embodiment, the visual target presentation device according to the present embodiment may be provided separately from the device for VDT operation, and may be used when the VDT operation is continued for a certain period of time or when eye fatigue occurs.

As described above, according to the present embodiment, by presenting the virtual image B (see fig. 2) projected by the concave mirror 2 as the visual target to the observer P, the moving distance of the image display device 1 can be shortened as compared with the case where the image itself from the image display device 1 is presented, and therefore, the area required for the movement of the image display device 1 can be reduced, and as a result, the size of the device itself can be reduced.

In addition, according to the present embodiment, the moving speed of the virtual image B is increased by increasing the position of the virtual image B as the optical distance between the image display device 1 and the concave mirror 2 is longerThe faster the time, the refractive power D of the lens 5 (see fig. 2) of the observer P can be changed not only when the virtual image B is located near the observation point but also when the virtual image B is located far from the observation pointIs constant or more. This can sufficiently relieve fatigue of the focus adjustment function of the observer P. The change in the focus adjustment function of the observer P can be made always constant or more regardless of whether the virtual image B is located far away or near.

Further, according to the present embodiment, since the half mirror 3 is obliquely crossed with the optical axis Lx of the concave mirror 2, when the virtual image B as the optotype appears to the observer P, the image display device 1 itself can be prevented from being an obstacle.

Further, according to the present embodiment, since the moving device 4 moves the image display device 1, the virtual image B can be moved, and therefore, compared to a case where the virtual image B is moved by, for example, the movement of the concave mirror 2, it is not necessary to change the positions of the eyes of the observer P. That is, the observer P can visually recognize the optotype at the same observation point.

Further, according to the present embodiment, since the virtual image B repeats the reciprocating motion, the refractive power D of the lens 5 of the observer P can be effectively changed, and thus fatigue of the focus adjusting function of the observer P can be further alleviated.

The visual target expression device of the present embodiment uses an image as an object, but as a modification of the visual target expression device, a three-dimensional object or the like may be used instead of an image. In this case, the three-dimensional object or the like is directly or indirectly attached to the support plate 40 and thus can move. In the configuration using a three-dimensional object or the like as an object, the visual target presenting device of the above modification can perform the same operation as in the present embodiment, and as a result, the same effect as in the present embodiment can be obtained. That is, since the moving speed of the virtual image of the three-dimensional object or the like becomes faster as the distance from the observation point increases, the temporal change in refractive power D of lens 5 of observer P can be made constant or more not only when the virtual image is located near the observation point but also when the virtual image is away from the observation point, and therefore fatigue of the focus adjustment function of observer P can be sufficiently alleviated. The change in the focus adjustment function of the observer P can be made always constant or more regardless of whether the virtual image is located far away or near.

In order to change the optical distance between the image display device 1 and the concave mirror 2, there are 3 types in total of a type of moving only the image display device 1, a type of moving only the concave mirror 2, and a type of moving both the concave mirror 2 and the image display device 1. The optotype presenting apparatus of the present embodiment includes a moving device 4 that moves only the image display device 1 as distance adjusting means. As a modification of the visual target expression device, a concave mirror moving device for moving the concave mirror 2 in the direction of the optical axis Lx of the concave mirror 2 may be provided as the distance adjustment means instead of the moving device 4 or together with the moving device 4. The visual target display device can move the virtual image B by moving the concave mirror 2. However, in order for the observer P to accurately observe the virtual image B, the position of the eyes of the observer P with respect to the concave mirror 2 is limited to a certain range. Therefore, when the concave mirror 2 is moved, the position of the eyes of the observer P also needs to be moved. Therefore, of the 3 modes described above, the mode of moving only the image display device 1 is most preferable and practical. That is, the moving device 4 of the present embodiment is superior and realistic to the concave mirror moving device in that it is not necessary to move the position of the eyes of the observer P as the distance adjusting means. The same applies to embodiments 2 to 10 below.

(embodiment mode 2)

However, in the conventional visual target display device, since the observer P (fig. 1) observes the object a via the concave mirror 70 whose mirror surface is a spherical surface, the virtual image B formed by the concave mirror 70 becomes a curved surface as shown in fig. 20. That is, in the conventional visual target display device, field curvature occurs. As a result, the observer P perceives the virtual image B stereoscopically (like a chordal type) due to binocular disparity, and particularly, the virtual image B is conspicuous in a horizontal direction which is a direction connecting both eyes. Specifically, the observer P feels the virtual image B due to the binocular disparity as in a chordal type where the center portion as the fixation point is concave and the end portions are curved to the hand side. That is, even if the surface of the object a is a flat object, the observer P recognizes the object a as a three-dimensional object by seeing the virtual image B of the object a.

The stereoscopic impression perceived by the observer P is a sense of depth of the virtual image B. In other words, the stereoscopic effect means: the observer P perceives a near visual target at a relatively close distance and a far visual target at a relatively far distance. Binocular parallax gives observer P a sense of stereoscopic sensation when points other than the fixation point are imaged at non-corresponding positions on the left and right retinas. When the observer P observes the virtual image B with both eyes, a point closer to the reference plane is perceived by the virtual image B closer to the reference plane and a point farther from the reference plane is perceived by the observer P than when the virtual image B is observed with one eye due to binocular parallax. Such a feeling is particularly noticeable in a horizontal direction as a direction connecting both eyes.

As described above, the virtual image B of the object a that the observer P perceives stereoscopically as being planar means: the observer P views the virtual image B in a distorted state, that is, the virtual image B is distorted.

Therefore, in the conventional visual target presentation device, when fatigue of the focus adjustment function of the observer P is relieved, the observer P visually recognizes the virtual image B having distortion, and the observer P may feel uncomfortable or uncomfortable.

As a conventional method for solving the above problem, it is considered to increase the radius of curvature of the mirror surface of the concave mirror 70. However, when the radius of curvature of the mirror surface of concave mirror 70 is simply increased, focal length f of concave mirror 70 becomes longer. According to equations (1) and (2), even if the object a is moved by the same amount as before, the moving range of the virtual image B becomes small and the magnification of the virtual image B becomes small. Therefore, in order to increase the moving range of the virtual image B, it is necessary to increase the moving range of the object a. As a result, both miniaturization of the visual target display device and movement of a large visual target cannot be achieved.

Therefore, in embodiment 2, a visual target presenting apparatus that solves the above-described problems will be described. According to the present embodiment, it is possible to provide a visual target presentation device that can be downsized and can provide the observer P with an effect of alleviating fatigue of the focus adjustment function of the eyes without causing distortion of the visual target.

First, the configuration of the visual target display device according to the present embodiment will be described. Fig. 1 shows a configuration of a visual target presenting apparatus according to the present embodiment. As shown in fig. 1, the visual target presenting apparatus includes an image display device 1, a concave mirror 2, a half mirror 3, and a moving device 4, as in the visual target presenting apparatus according to embodiment 1. The above-described visual target visualizing apparatus visualizes a virtual image B (see fig. 17) imaged by the concave mirror 2 to an observer P as a visual target.

The image display device 1 of the present embodiment has the same configuration as the image display device 1 of embodiment 1. The image display device 1 of the present embodiment is a device for generating a visual target, and corresponds to an object of the present invention.

Next, the design of the concave mirror 2 in a two-dimensional plane (xy plane of fig. 5) will be described with reference to fig. 5. In fig. 5, the half mirror 3 (see fig. 1) is omitted for convenience of explanation, and only the image display device 1 and the concave mirror 2 are shown. The mirror surface of the concave mirror 2 is an aspherical elliptic spherical surface, and the image display device 1 is a plane surface. The design parameters are as follows: axes of the concave mirrors 2 are m1 and m2, a width of the concave mirror 2 is lm, a width of the image display device 1 is ls, a width of an entrance pupil of the observer P is le, a position of the image display device 1 is xs, a position of the entrance pupil of the observer P is xe, and a maximum angle of light emitted from each point on the image display device 1 is θ max.

The imaging position of the virtual image B is determined in the following manner in consideration of the spherical aberration. As shown in fig. 6A, when the reflected light reflected by the concave mirror 2 among the light emitted in the θ direction from an arbitrary point (xs, ys) on the image display device 1 is extended virtually to the rear surface side of the concave mirror 2 (x > 0), the light from the image display device 1 passes through the point (x, y (x, θ, xs, ys)) of the arbitrary x (> 0). When y is considered in the range of- θ max < θ max, then y corresponding to any x has a probability distribution as shown in fig. 6B. The deviation of y corresponding to an arbitrary x is represented by a standard deviation σ ═ σ (x, xs, ys). When xf is defined as x that is the smallest standard deviation among the standard deviations σ of x, the imaging position (xf, yf) of the virtual image B, which is generated by light emitted from the point (xs, ys) of the image display device 1 in the direction of- θ max < θ max, is (xf, μ (y)). When x is xf, μ (y) is the average value of y (xf, θ, xs, ys) in the range of- θ max < θ max. The imaging position (xf, yf) of the virtual image B is a position at which, of the light emitted from the point (xs, ys) on the image display device 1 in the direction- θ max < θ max, the reflected light reflected by the concave mirror 2 virtually converges to the closest position on the back surface side of the concave mirror 2.

In the present embodiment, each design parameter shown in fig. 5 is lm 150mm, ls 70mm, le 100mm, xe 100mm, and θ max 10 deg. The reflectance of the concave mirror 2 is 1.0. The mirror surface of the concave mirror 2 is formed into an elliptic spherical surface (aspherical surface) (m1, m2) ((300 mm, 310 mm)). In the concave mirror 2 of the present embodiment, the axis m2 is longer than the axis m1, and the radius of curvature of the mirror surface of the concave mirror 2 increases toward the center. Specifically, the radius of curvature of the end portions was 318.44mm relative to the radius of curvature of the central portion of 320.33 mm. The mirror surface of the concave mirror 2 is a spherical surface in a z direction (2 nd direction) orthogonal to a y direction (1 st direction) connecting both eyes of the observer P. Therefore, in the concave mirror 2, the ratio of the radius of curvature of the central portion of the mirror surface to the radius of curvature of the end portion is larger in the y direction than in the z direction. Next, a virtual image (comparative example 1) formed by a concave mirror having a spherical surface with a mirror surface of (m1, m2) ═ 300mm, 300mm) and a virtual image (comparative example 2) formed by a concave mirror having a spherical surface with a mirror surface of (m1, m2) ═ 310mm, 310mm) will be described with reference to the virtual image B formed by the concave mirror 2 of the present embodiment.

Fig. 7 shows the shape of the virtual image B when the distance xs is selected so that the positions of the center portions of the virtual image B in the x direction coincide with each other in the present embodiment (E1 in fig. 7), comparative example 1(E1), and comparative example 2 (E2). When the difference between the positions of the end portions and the central portion of the virtual image B in the x direction is δ, δ is 1086.0mm in the present embodiment, 1424.4mm in comparative example 1, and 1324.2mm in comparative example 2. The difference δ in position in the present embodiment is 23.8% smaller than comparative example 1 and 18.0% smaller than comparative example 2. In summary, the distortion of the present embodiment in which the mirror surface is aspheric is the smallest. The distance xs is-155.1 mm in the present embodiment, 145.5mm in comparative example 1, and 150.2mm in comparative example 2.

As described above, by making the mirror surface of the concave mirror 2 aspherical, and in particular, by making the radius of curvature of the central portion of the mirror surface larger, the distortion of the virtual image B, that is, the stereoscopic effect of the virtual image B can be reduced as compared with the case where the mirror surface of the concave mirror 2 is spherical. The concave mirror 2 of the present embodiment corresponds to the reducing means of the present invention.

In the present embodiment, the control unit 45 also controls the operation of the motor 44 such that the movement speed of the image display device 1 is faster as the optical distance between the image display device 1 and the concave mirror 2 is longer. By moving the image display device 1 as described above, the moving speed of the virtual image B can be increased more effectively as the distance from the crystalline lens increases, and therefore fatigue of the focus adjusting function of the observer P can be reduced.

The operation of the visual target presenting device when the observer P uses the visual target presenting device of the present embodiment is the same as that of the visual target presenting device of embodiment 1.

As another use example of the visual target presentation device according to the present embodiment, the visual target presentation device may be provided separately from the device for VDT operation, and may be used when the VDT operation is continued for a certain period of time or when the eyes are fatigued.

As described above, according to the present embodiment, by reducing distortion (stereoscopic effect) of the virtual image B serving as the optotype, it is possible to provide the observer P with an effect of preventing fatigue of the focus adjustment function of the eyes without conscious of distortion of the optotype.

Further, according to the present embodiment, by making the mirror surface of the concave mirror 2 aspherical and increasing the radius of curvature of the central portion of the mirror surface of the concave mirror 2, the effect of reducing the distortion of the optotype can be improved regardless of whether the image display surface 10 (front surface) of the image display device 1 is a flat surface or a curved surface. In particular, in the present embodiment, the distortion of the visual target can be made smaller in the y direction than in the z direction (2 nd direction) orthogonal to the y direction by increasing the ratio of the curvature radii of the central portion to the end portions of the mirror surface in the y direction (1 st direction) of the both eyes connecting the observer P, and therefore, it is possible to suppress the virtual image B from being largely distorted due to binocular parallax and to appear stereoscopic.

Further, the visual target presenting apparatus of the present embodiment uses the image display apparatus 1 as the object, but as a modification of the visual target presenting apparatus, a three-dimensional object may be used as the object without using the image display apparatus 1. In this case, the three-dimensional object is directly or indirectly mounted on the support plate 40 and thus is movable. The configuration using such a three-dimensional object as an object can perform the same operation as in the present embodiment, and as a result, the same effect as in the present embodiment is obtained. The same applies to embodiments 3 to 5 and 7 to 10 below.

In addition, as a modification of the present embodiment, the mirror surface of the concave mirror 2 may be aspheric in the z direction orthogonal to the y direction connecting the eyes of the observer P. In this case, the mirror surface of the concave mirror 2 is an elliptic spherical surface (300mm, 310mm) in the z direction as well as in the y direction, and the radius of curvature of the central portion is 320.33mm, while the radius of curvature of the opposite end portion is 318.44 mm.

(embodiment mode 3)

In embodiment 3, a case where a concave mirror 2 larger than the concave mirror 2 of embodiment 2 is used will be described.

In the present embodiment, each design parameter (see fig. 5) is: lm 600mmls 280mm, le 100mm, xe 600mm and θ max 10 deg. The mirror surface of the concave mirror 2 of the present embodiment is an elliptic spherical surface having a value of (1200mm, 1300mm) from (m1, m 2). The mirror surface of the concave mirror 2 of the present embodiment has a curvature radius of 1408.33mm at the center and 1389.02mm at the opposite ends. Next, a virtual image (comparative example 3) formed by a concave mirror having a spherical surface with a mirror surface of (m1, m2) ═ 1200mm, and a virtual image (comparative example 4) formed by a concave mirror having a spherical surface with a mirror surface of (m1, m2) ═ 1300mm, 1300mm) will be described with reference to the virtual image B formed by the concave mirror 2 of the present embodiment. The design parameters of the concave mirror 2 in the xz plane are the same as those of the concave mirror 2 in the xy plane. That is, the mirror surface of the concave mirror 2 is also an elliptic spherical surface (1200mm, 1300mm) in the z direction, and the radius of curvature of the central portion is 1408.33mm, whereas the radius of curvature of the end portions is 1389.02 mm.

Fig. 8 shows the shape of the virtual image B when the distance xs is selected so that the positions of the center portions of the virtual image B in the x direction coincide with each other in the present embodiment (E2 in fig. 8), comparative example 3(E3), and comparative example 4 (E4). When the difference between the positions of the end portions and the central portion of the virtual image B in the x direction is δ, δ is 138.6mm in the present embodiment, 591.6mm in comparative example 3, and 383.8mm in comparative example 4. The difference δ in position in the present embodiment is 76.6% smaller than comparative example 3 and 62.9% smaller than comparative example 4. In summary, the distortion of the present embodiment in which the mirror surface is aspheric is the smallest. Furthermore, the distance xs is-620.6 mm in example 2, -538.2mm in comparative example 3, and-578.1 mm in comparative example 4.

As described above, even when the concave mirror 2 is large as in the present embodiment, distortion of the optotype can be reduced, and therefore, the observer P can be given the effect of preventing fatigue of the focus adjustment function of the eyes without being conscious of distortion of the optotype.

(embodiment mode 4)

In embodiment 4, a case will be described where a concave mirror 2 smaller than the concave mirror 2 of embodiment 2 is used.

In the present embodiment, each design parameter (see fig. 5) is: lm is 50mm, ls is 24mm, le is 15mm, xe is-50 mm, and θ max is 10deg, considering monocular vision. The concave mirror 2 of the present embodiment is an elliptic spherical surface having a mirror surface of (m1, m2) ═ 100mm, 105 mm. The mirror surface of the concave mirror 2 of the present embodiment has a curvature radius of 110.25mm at the center, and 109.30mm at the end. Next, a virtual image (comparative example 5) formed by a concave mirror having a spherical surface with a mirror surface of (m1, m2) ═ 100mm, and a virtual image (comparative example 6) formed by a concave mirror having a spherical surface with a mirror surface of (m1, m2) ═ 105mm, 105mm) will be described with reference to the virtual image B formed by the concave mirror 2 of the present embodiment. The design parameters of the concave mirror 2 in the xz plane are the same as those of the concave mirror 2 in the xy plane. That is, the mirror surface of the concave mirror 2 is also an elliptic spherical surface (100mm, 105mm) in the z direction, and the radius of curvature of the central portion is 110.25mm, whereas the radius of curvature of the end portions is 109.30 mm.

Fig. 9 shows the shape of the virtual image B when the distance xs is selected so that the positions of the center portions of the virtual image B in the x direction coincide with each other in the present embodiment (E3 in fig. 9), the comparative example 5(E5), and the comparative example 6 (E6). When the difference between the positions of the end portions and the central portion of the virtual image B in the x direction is δ, δ is 1602.4mm in the present embodiment, 2849.6mm in comparative example 5, and 2423.2mm in comparative example 6. The difference δ in position in the present embodiment is 43.8% smaller than comparative example 5 and 33.9% smaller than comparative example 6. In summary, the distortion of the present embodiment in which the mirror surface is aspheric is the smallest. The distance xs is-54.5 mm in the present embodiment, -49.4mm in comparative example 5, and-51.9 mm in comparative example 6.

As described above, even when the concave mirror 2 is small as in the present embodiment, distortion of the optotype can be reduced, and therefore, the observer P can be given the effect of preventing fatigue of the focus adjustment function of the eyes without being conscious of distortion of the optotype.

(embodiment 5)

In embodiment 5, a case where the image display device 1 is not a flat surface but a curved surface will be described. That is, in the present embodiment, the image display surface 10 on which an image is displayed is a curved surface.

As the image display device 1 of the present embodiment, a flexible display that can be freely bent is used. Examples of the flexible displays include organic EL displays using a plastic film for a substrate, and electronic papers using an electrophoretic method. The image display device 1 of the present embodiment corresponds to the object and the lowering means of the present invention.

However, the horizontal direction (y direction in fig. 1) as a direction connecting both eyes is more sensitive to distortion of the virtual image B due to the influence of binocular parallax than the vertical direction (direction orthogonal to the horizontal direction, z direction in fig. 1). Therefore, in the present embodiment, in consideration of the ease of manufacturing the image display device 1, the image display device 1 is formed in a shape in which a convex curvature is imparted to the concave mirror 2 side, that is, a shape of a part of a cylinder (a cross section is an arc shape), only in a direction in the horizontal direction when an image displayed on the image display device 1 is projected onto the concave mirror 2. That is, in fig. 10, the image display device 1 is projected to the right side in the y direction, but is projected to the lower side in the actual visual target visualizing device (fig. 1).

As shown in fig. 10, the design parameters used in the present embodiment are: axes m1, m2 of the concave mirror 2, a width lm of the concave mirror 2, a width ls of the image display device 1, a width le of an entrance pupil of the observer P, xs (xs) (y) indicating a shape and a position of the image display device 1, a position xe of the entrance pupil of the observer P, and a maximum angle θ max of light emitted from each point on the image display device 1. The design parameters are as follows: lm 150mm, ls 70mm, le 100mm, xe-100 mm and θ max 10 deg. The concave mirror 2 of the present embodiment is a spherical surface having a mirror surface of (m1, m2) ═ 300mm, 300 mm). The reflectance of the concave mirror 2 is 1.0. On a two-dimensional plane (xy plane of FIG. 10), an image is displayedThe device 1 (light source) is an arc-shaped light source having a vertex of xs (0) — 145.5mm, which projects toward the concave mirror 2 side, and has a radius of r of 450mm, that is, { xs (y) ((450))²-y²)^1/2-595.5mm }. Next, the image display device 1 of the present embodiment and an image display device as a "linear light source" { xs (y) — 145.5mm ═ constant value } (comparative example 7) will be described while comparing them. Fig. 11 shows the shape of the image display device 1 according to the present embodiment and comparative example 7. E5 in fig. 11 is the present embodiment, and E7 is a comparative example.

As shown in fig. 12, when the difference between the positions of the end portion and the central portion of the virtual image B in the x direction is δ, δ is 220.80mm in the present embodiment (E4 in fig. 12), and δ is 1424.4mm in comparative example 7 (E7). The difference δ in position in the present embodiment is 84.5% smaller than that in comparative example 7. As described above, in the present embodiment, the distortion of the virtual image B can be reduced as compared with comparative example 7.

Here, the shape of the image display device 1 that minimizes distortion of the virtual image B changes depending on the average distance between the concave mirror 2 and the image display device 1. Therefore, in the present embodiment, a mechanism is provided for changing the shape of the image display device 1 in accordance with the distance between the image display device 1 and the concave mirror 2.

As described above, according to the present embodiment, the image display surface 10 (surface) of the image display device 1 (object) is formed as a curved surface, and therefore, the effect of reducing distortion of the optotype can be enhanced regardless of whether the mirror surface of the concave mirror 2 is a spherical surface or an aspherical surface.

In addition, according to the present embodiment, since the image display device 1 protrudes toward the concave mirror 2, distortion of the optotype can be further reduced.

Further, according to the present embodiment, the direction (y direction) connecting the both eyes of the observer P when projected by the concave mirror 2 can particularly reduce the distortion of the virtual image B, and therefore it is possible to more suppress the virtual image B from appearing stereoscopic despite being planar due to binocular parallax.

As a modification of the present embodiment, the shape of the image display device 1 may be a shape that is curved in the vertical direction, not a shape of a part of a cylinder that is not curved in the vertical direction (a direction orthogonal to the horizontal direction as the direction connecting both eyes).

Further, the image display device 1 having a curved surface as in embodiment 5 may be combined with the concave mirror 2 having a mirror surface with an aspherical surface as in embodiments 2 to 4. For example, the concave mirror 2 is an elliptical spherical surface having a mirror surface of (m1, m2) — (300mm, 310mm), and the image display device 1 is an arc-shaped light source of "xs (0) — 145.5mm as a vertex, and r 450mm as a radius protruding toward the concave mirror 2 side", that is, { xs (y) — (450 mm)²-y²)^1/2-595.5mm }. The design parameters are the same as those of embodiment 5. Such a configuration also provides the observer P with an effect of preventing fatigue of the focus adjusting function of the eyes without consciously distorting the optotype.

(embodiment mode 6)

In embodiment 6, a case will be described in which an image in which distortion of the virtual image B is considered in advance is displayed on the image display device 1. The image of the present embodiment is subjected to image processing in advance and is deformed so as to reduce distortion (stereoscopic effect) of the virtual image B when projected on the concave mirror 2.

The image display device 1 of the present embodiment is a flat panel display as in embodiment 2. The image display device 1 of the present embodiment is integrally or separately provided with an image processing unit (not shown) that performs image processing based on a predetermined rule. In the present embodiment, the image displayed on the flat panel display corresponds to the object and the lowering means of the present invention.

As described above, according to the present embodiment, since the image displayed on the flat panel is deformed in advance, the effect of reducing the distortion of the optotype can be improved regardless of whether the mirror surface of the concave mirror 2 is a spherical surface or an aspherical surface. That is, even when the image is deformed in advance as in the present embodiment, distortion of the virtual image B can be reduced, and therefore, an effect of preventing fatigue of the focus adjustment function of the eyes can be provided to the observer P without awareness of distortion of the optotype.

Furthermore, the image in which the pre-distortion is taken into consideration as in embodiment 6 may be combined with the concave mirror 2 having an aspherical mirror surface as in embodiments 2 to 4. Such a configuration also provides the observer P with an effect of preventing fatigue of the focus adjusting function of the eyes without consciously distorting the optotype.

(embodiment 7)

However, in embodiments 2 to 6, the objective is to image the virtual image B more planarly. However, actually, it is generally considered that a set of points imaged at corresponding positions of both eyes, that is, a parallax reference plane (monocular vision) is curved in the direction of the eye position in the left-right end direction when the observer P gazes at the point M as shown in fig. 19 (H1 in fig. 19). This is referred to as empirical monocular distance H1.

Therefore, in embodiment 7, a case where binocular parallax is taken into consideration will be described with reference to fig. 19. In the present embodiment, the shape of the image display device 1, the shape of the mirror surface of the concave mirror 2, and the like are deformed so that the virtual image B coincides with a predetermined surface. The predetermined surface is: for example, the empirical monocular vision H1 of a plurality of persons is measured in advance, and the measured empirical monocular vision H1 is averaged to obtain a surface. As another example, when the observer P is identified, the empirical monocular vision H1 of the observer P may be measured, and the empirical monocular vision H1 may be set to the predetermined plane. In order to match the virtual image B with the empirical monocular visibility H1, design parameters relating to the shape of the mirror surface of the concave mirror 2 and the surface shape of the image display device 1 need to be designed in detail.

As described above, according to the present embodiment, the observer P can clearly observe the entire virtual image by matching the virtual image B with the empirical monocular distance H1.

Furthermore, geometrically, binocular single vision refers to: when the observer P gazes at point M, the circle M-O1-O2 is obtained by setting the nodes of both eyes to O1 and O2 (H2 in fig. 19). This is referred to as the geometric binocular single vision H2. It is known that the monoocular field H1 is not consistent with the geometric monoocular field H2 based on the experience of the organism's subjectivity.

(embodiment mode 8)

In embodiment 8, an image display system using the visual target presenting apparatuses according to embodiments 1 to 7 will be described with reference to fig. 13. Examples of the image display system include a television receiver and a projector. The image display system of the present embodiment includes the image display device 1 together with the above-described visual target presenting device. That is, the optotype presenting device of the present embodiment includes the concave mirror 2, the half mirror 3, and the moving device 4, but is separate from the image display device 1. The image display device 1 of the present embodiment has a function of displaying images (including video) as in the image display devices 1 of embodiments 1 to 7.

However, when the optotype presenting apparatuses according to embodiments 1 to 7 are used as an image display system, the image display system includes the concave mirror 2 and the half mirror 3, and thus has a larger size than a thin television or the like, and therefore requires a large installation space.

Therefore, as shown in fig. 13, the image display system of the present embodiment is provided embedded in the space S between the wall W1 and the wall W2. An opening Wa is formed in the wall W1.

The concave mirror 2 of the present embodiment is provided along the wall W2 side. The concave mirror 2 is opposed to the opening Wa. The half mirror 3 of the present embodiment is provided between the concave mirror 2 and the opening Wa. In the present embodiment, since the concave mirror 2 is provided in the space S, the curvature of the concave mirror 2 can be reduced. This improves the visibility of the optotype by the observer P.

The image display device 1 of the present embodiment is disposed above the half mirror 3 in the space S. The image display surface 10 faces downward. As the image display device 1, a liquid crystal display, a rear projection, or the like is used. The image from the image display apparatus 1 may be a television program or a reproduced image from a reproduction device (not shown). The image display apparatus 1 is moved in the vertical direction by the moving device 4. Thus, the optotype presenting apparatus of the present embodiment can change the optical distance between the image display device 1 and the half mirror 3, and as a result, can change the optical distance between the image display device 1 and the concave mirror 2.

In the present embodiment, an image from the image display device 1 is reflected at the half mirror 3 toward the concave mirror 2. The virtual image B is displayed from the concave mirror 2 to the observer P through the half mirror 3 and the opening Wa. Thus, the visual target presenting device of the present embodiment can present the virtual image B of the image displayed by the image display device 1 to the observer P as a visual target.

As described above, according to the present embodiment, even if the image display system using the optotype presenting apparatus is large, by fitting the image display system into the space S inside the wall, the living space can be widened and the interior decoration can be enhanced as compared with the case where the image display system is provided so as to protrude from the wall W1 (see fig. 14).

Further, as a modification of the present embodiment, an image display system using a visual target display device may be installed by being embedded in a space on the ceiling.

(embodiment mode 9)

In embodiment 9, a case where a visual target presentation device is used as a display device in an automobile (hereinafter referred to as an "in-vehicle display device") will be described. The in-vehicle display device includes an image display device 1 for providing information related to driving together with the visual target presentation device. Examples of the on-vehicle display device include an instrument panel and a display unit of a navigation system.

The driver looks far or near during driving according to different scenes. On the other hand, the in-vehicle display device is fixed at a position close to the actual distance between the display device and the driver, which is within about 1 m. When there is a gap between the front visual distance and the visual distance displayed in the vehicle by the in-vehicle display device, the driver needs to change the focus adjustment function when he wants to visually recognize the front and in-vehicle displays alternately. In particular, when the gaze point is moved to the far front side from the near in-vehicle display, the time becomes longer. In addition, at night when the pupil is spread, the time is longer than that in the daytime.

Therefore, as shown in fig. 15A and 15B, the visual target visualizing device of the present embodiment includes a visual range estimating device 9 in order to shorten the time required for the change of the focus adjustment function of the driver (observer P). The visual range estimator 9 estimates the visual range of the driver. The visual target presenting apparatus of the present embodiment includes a concave mirror 2, a half mirror 3, and a moving device 4, as in the visual target presenting apparatus of embodiment 1. The image display device 1 of the present embodiment has the same function as a conventional in-vehicle display device.

An example of the visual range estimator 9 is shown below. The visual range estimation device 9 includes an observation unit 90 and an analysis unit 91. The observation portion 90 observes both eyes of the driver. The analysis unit 91 analyzes the viewing directions of the driver's eyes from the observation images to estimate the viewing distance from the convergence. The visual target display device changes the optical distance between the image display device 1 and the concave mirror 2 in accordance with the visual distance estimated by the visual distance estimation device 9, thereby changing the visual distance of the virtual image B displayed in the vehicle. For example, in the case of recognition of distant vision, as shown in fig. 15A, the visual distance of the virtual image B becomes longer. On the other hand, in the case of near vision recognition, as shown in fig. 15B, the visual distance of the virtual image B becomes short. This enables the visual range of the in-vehicle display to be matched with the visual range in front.

As described above, according to the present embodiment, the time required for the driver (observer P) to change the focus adjustment function can be shortened by matching the visual range of the driver looking forward during driving with the visual range displayed in the vehicle interior.

As a modification of the present embodiment, the visual range estimator 9 may be provided separately from the visual target displaying device.

As another modification of the present embodiment, the in-vehicle display device may have a function of fixing the position of the virtual image B displayed in the vehicle in a state where the viewing distance of the virtual image B is long. This makes it possible to avoid a situation in which the driver visually recognizes the far front immediately after visually recognizing the near in-vehicle display, that is, a situation in which the time required for the driver to change the focus adjustment function is longer than other situations. Further, since the visual target presentation device does not need to include the visual recognition estimating device 9, the configuration of the in-vehicle display device can be easily provided.

The above description is only a preferred embodiment of the present invention and does not limit the scope of the present invention. Variations and modifications within the scope of the description that may occur to those skilled in the art are also within the scope of the invention.

The present application claims the priority of Japanese patent application No. 2008-278806, which was applied to the office at 10/29 of 2008, and Japanese patent application No. 2009-175857, which was applied to the office at 7/28 of 2009. The contents of the above-mentioned japanese patent application are fully incorporated into the present application.

Claims (20)

1. A visual target presenting device for presenting a virtual image of an object to an observer as a visual target,

comprises a concave mirror and a distance adjusting unit,

the concave mirror is disposed such that an optical distance between the concave mirror and the object is shorter than a focal distance of the concave mirror, and is used to form the virtual image,

the distance adjustment means is configured to change the optical distance in a range shorter than a focal distance of the concave mirror, and to increase a moving speed of the virtual image as the virtual image position is farther.

2. The visual target presenting device according to claim 1,

comprises a half mirror obliquely arranged with respect to the optical axis of the concave mirror,

the object is configured to be reflected on the concave mirror side of the half mirror and projected onto the concave mirror, and a virtual image of the object is visualized to the observer via the half mirror.

3. The visual target presenting device according to claim 1,

the distance adjusting means moves the object.

4. The visual target presenting device according to claim 3,

the distance adjusting means increases the moving speed of the object as the optical distance is longer.

5. The visual target presenting device according to claim 4,

the observation point is positioned in front of the concave mirror,

the distance adjustment means moves the object so that a temporal change of an inverse of the distance between the observation point and the virtual image of the object is constant.

6. The visual target presenting device according to claim 3,

the distance adjusting means changes the optical distance so as to repeat the reciprocating motion of the optotype.

7. The visual target presenting device according to claim 6,

the distance adjusting means periodically moves the optotype.

8. The visual target presenting device according to claim 3,

the distance adjusting means continuously moves the optotype.

9. The visual target presenting device according to claim 1,

the image processing apparatus includes a flat panel display for displaying an image of the object.

10. The visual target presentation device according to any one of claims 1 to 9,

the image processing apparatus includes a reduction unit for reducing distortion of the virtual image.

11. The visual target presenting device according to claim 10,

the lowering unit is formed using the concave mirror,

the mirror surface of the concave mirror is formed to be aspherical so as to reduce distortion of the virtual image.

12. The visual target presenting device according to claim 11,

in the concave mirror, the radius of curvature of the mirror surface increases toward the center of the mirror surface.

13. The visual target presenting device according to claim 12,

when the viewer is presented with the sight mark, the ratio of the radius of curvature of the mirror surface at the center to the radius of curvature of the end is larger in the 1 st direction connecting both eyes of the viewer than in the 2 nd direction orthogonal to the 1 st direction.

14. The visual target presenting device according to claim 10,

the lowering unit is formed using the object,

the surface of the object is formed into a curved surface so as to reduce distortion of the virtual image.

15. The visual target presenting device according to claim 14,

the object is projected toward the concave mirror.

16. The visual target presenting device according to claim 15,

the object is cylindrically curved, and when the sight is displayed to the observer, the axial direction of the object is orthogonal to the direction connecting the eyes of the observer.

17. The visual target presenting device according to claim 10,

a flat panel display is provided with a display device for displaying an image,

the lowering unit is formed using the object,

the object is an image displayed by the flat panel display,

the image is deformed in advance so as to reduce distortion of the virtual image when projected onto the concave mirror.

18. An image display system characterized in that,

a visual target display device according to claim 1; and

an image display device for displaying an image is provided,

the visual target presenting device presents a virtual image of the image displayed by the image display device to the observer as the visual target.

19. A display device for vehicle use, characterized in that,

a visual target display device according to claim 1; and

an image display device for providing driving-related image information,

the visual target presenting device presents a virtual image of the information provided by the image display device to the observer as the visual target.

20. The in-vehicle display device according to claim 19,

the visual target display device includes a visual distance estimation device that estimates a visual distance of the observer, and changes an optical distance between the image display device and the concave mirror so that the visual distance of the virtual image increases as the visual distance of the observer increases.