KR102133880B1 - Three dimensional image display apparatus without vergence-accommodation conflict - Google Patents

Abstract

The present invention relates to a stereoscopic image display device in which a convergence distance and an adjustment distance are the same, so that a problem due to a convergence-adjustment mismatch (hereinafter referred to as VAC) in a stereoscopic image that is commonly commercialized does not appear. , According to the present invention, one or more light sources 100 for irradiating stereoscopic content; A dimming unit 200 for adjusting the intensity and direction of light from the one or more light sources; And an optical unit 400 that receives the controlled light from the dimming unit and forms an image of a three-dimensional content at a point P1 on the optical axis and displays the image, and the optical unit 400 receives the incident light. A microlens array 410 that diffuses and transmits to a small lens array 430 at the rear end, a small lens array 430 composed of a plurality of small lenses, and each small lens parallels the light transmitted from the microlens array 430. It includes a small lens array 430 that converts light, and one large convex lens 450 that forms parallel light transmitted from the small lens array 430 at a point P1 on the optical axis.

Description

THREE DIMENSIONAL IMAGE DISPLAY APPARATUS WITHOUT VERGENCE-ACCOMMODATION CONFLICT}

The present invention relates to a stereoscopic image display device, and more specifically, due to the same convergence distance and an adjustment distance, due to a convergence-adjustment mismatch (hereinafter referred to as VAC) in a commercially available stereoscopic image The present invention relates to a stereoscopic image display device having no problem.

Efforts to display objects exactly as we see them have been going on for a long time, and the demand for stereoscopic display devices continues to increase.

The three-dimensional display can be categorized into four types as follows.

A) Stereoscopic method

B) Auto-stereoscopic method

C) Volumetric method

D) Holographic method

The methods are briefly described as follows.

First, stereoscopy (glasses-type stereoscopic image display) is a way to make the sense of distance by slightly differentizing the visible images. Since this method is relatively easy to implement, the 3D movie market was predicted to develop explosively when the first 3D movie was produced and aired, but this method does not match the convergence (Vergence) and adjustment (or focus) (Accommodation). Therefore, 3D images could not be viewed for a long time because they caused fatigue or dizziness in the eyes due to a convergence-control (focus) mismatch (hereinafter referred to as VAC). Nevertheless, it is still popular as a VR display to this day due to the advantage that it can be implemented at a relatively low cost.

In order to help understanding of the present invention, the concept of adjustment and convergence will be briefly described.

1A is a diagram for explaining the concept of convergence. As shown in Fig. 1A, convergence represents a process in which two eyes move in opposite directions to obtain one fused image for an object.

In FIG. 1A, (a) is when two eyes look at an object at a short distance, (b) is looking at an object at a medium distance, and (c) is when looking at a object at a distance. When looking at an object at a distance, the angle θ1 of both eyes has a larger angle than the angle θ3 of both eyes. In other words, the eyes of a person's eyes converge toward the inside of the face centerline when looking at a close object, and conversely, when looking at a very distant object, the eyes are almost parallel to the face centerline.

1B is a view for explaining the concept of adjustment or focus (Accommodation). As shown in FIG. 1B, the adjustment is to adjust the shape and thickness of the lens to focus on an object located at a specific distance, that is, to mean an adjustment process of the lens for focusing.

The human eye adjusts the thickness of the lens as shown in FIG. 1B to obtain a clear image of the object. When focusing on a nearby object, the lens becomes thicker, and when focusing on a distant object, the lens becomes thinner. Due to the accommodation of the lens, the human eye can obtain a clear image regardless of the distance the object is placed.

Figure 1c (a) shows the convergence-regulating state of the human eye in a normal situation. The convergence and adjustment distances as described above are usually the same when watching a movie on a 2D screen, or in everyday situations.

However, in the case of a 3D display device using a binocular parallax such as a stereoscopic method, the convergence-adjusting states having mutual dependencies are shifted. This is known as a convergence-adjustment mismatch (or a convergence-adjustment distance mismatch) (Vergence-Accommodation Conflict: VAC) problem, and FIG. 1C(b) schematically shows a convergence-regulation mismatch condition in the human eye.

As shown in (b) of FIG. 1C, the human two eyes perform an accommodation to focus on a screen screen, whereas in a scene in which a stereoscopic 3D imaging technique is applied, objects appear in front of the screen. As it appears, the human eye again attempts to converge on the objects in front. At the same time, the human eye also tries to focus on the screen screen to get a clear image.

That is, the adjustment distance is always the same from the two eyes to the screen screen, and as the convergence distance is continuously changed according to the degree of disparity, the interdependent convergence and adjustment actions will operate independently of each other. Symptoms such as eye fatigue, dizziness, or vomiting are caused as the brain interpreting visual signals coming from the eye becomes confused.

Due to this convergence-adjustment mismatch, 3D TV, which once appeared in front of the public, is gradually disappearing. The problem caused by such a convergence-adjustment mismatch cannot be solved even if the resolution of the display itself is increased.

Next, in the auto-stereoscopy (autostereoscopic) display system, the stereoscopic display described above uses glasses or goggles while wearing nothing on the eyes. This is a method of realizing a stereoscopic image by attaching a simple device to the device. However, this method has the same convergence and control distance, so dizziness or vomiting appear the same. However, there is an advantage over the stereoscopic method in that nothing is worn on the eyes, but there is a disadvantage that the visible position is limited and the resolution is poor.

Next, the stereoscopic image display apparatus of the volumetric method is a method of realizing a stereoscopic image by converging light in the air with a laser. Since this method emits light at a desired point in the air, it does not cause problems such as fatigue or dizziness in the eyes due to convergence and mismatch as described above, but the space in which the image is displayed is limited and the device must be continuously moved mechanically. Due to the inconvenience and limitation of the laser scanning speed, it has not been widely commercialized.

Finally, the holography method is a method of recording an interference pattern of light and diffracting the light when the recorded pattern is reproduced to realize an image of an object to be originally displayed. Still images have evolved with the development of lasers long ago, but moving videos are still difficult to implement. The reason is, in order to realize a realistic video using holography, first, the size of the inter-pixel spacing of the SLM (spatial light modulator) must be reduced to less than or equal to the wavelength of visible light (0.5 µm), but the size of the pixel has to be reduced. It is very difficult to make it small, and secondly, the number of data required to realize a stereoscopic video using holography becomes astronomically large. In addition, the holographic display device requires a high manufacturing cost such as high diffraction efficiency, ultra-high resolution pixel addressing driving technology, large area coherent surface light source, or noise-free LED light source, so that the holographic stereoscopic image display Although the device is an optimal technology capable of realizing a natural stereoscopic image, it is impossible to implement it at a low cost or even at a high cost with the currently known technology.

The present invention is an invention devised to solve the above-described problems, and the dizziness, eye fatigue, and vomiting caused by a convergence-control mismatch are not induced, and thus a stereoscopic body that can be naturally recognized by the human eye. It is an object to provide an image display device.

In addition, an object of the present invention is to provide a stereoscopic image display apparatus capable of realizing a natural moving image such as holography, which is cost-saving through a relatively simple structure.

According to one aspect of the present invention to solve the above-described problem, a stereoscopic image display device having the same convergence distance and an adjustment distance is provided. The apparatus includes one or more light sources for irradiating stereoscopic content; A dimming unit for adjusting intensity and direction of light from the one or more light sources; And an optical unit that receives the controlled light from the dimming unit and forms an image of a stereoscopic image at a point on the optical axis, and displays the image.

The optical unit is a small lens array composed of a plurality of small lenses that diffuses incident light and transmits it to a small lens array at the rear end. Each small lens converts light transmitted from the micro lens array into parallel light. A characteristic configuration includes a small lens array, and one large convex lens that forms parallel light transmitted from the small lens array at a point P1 on the optical axis.

In the above-described aspect, the dimming unit includes a light modulator for adjusting the intensity of light and a light deflector for adjusting the direction of light.

In addition, in the above-described aspect, the light source is one or more laser diodes, and the light modulator is modulated through a direct modulation method that directly changes the current input to the laser diode, or an acoustic optic modulator and an electronic light modulator. It may be modulated by an external modulation device including any one of (Electro Optic Modulator).

Also in another aspect described above, the light source is one or more laser diodes, and the optical deflector is a 2D deflector that deflects modulated light in two-axis spaces on the x-axis and the y-axis, and the optical deflector is an acoustic light deflector (Acousto It may be selected from the group consisting of Optic Deflector, Electro Optic Deflector, Polygon Mirror and Galvanometer Mirror.

In addition, in the above-described aspect, the distance from the light exit surface of the small lens array to the light entrance surface of the large convex lens increases as the distance from the optical axis increases.

Further, in the above-described aspect, when the distance from the light exit surface of the small lens array to the light incident surface of the large convex lens is the same, the large convex lens may be formed aspherical.

In addition, in the above-described aspect, the stereoscopic image display device further includes an image enlargement unit in the vicinity of P1 to enlarge the image formed at the point P1, and the image enlargement unit is configured by a person who sees light converging from the convex lens to the point P1. It includes a Fresnel Lens unit that turns to a position, and a translucent concave mirror unit that converges light from the Fresnel Lens unit to a point P2 that is a stereoscopic image display area.

In the above-described aspect, the Fresnel lens unit sequentially includes a Fresnel lens, a first absorbing polarizing plate coupled to the exit surface side of the Fresnel lens, and a first λ/4 phase retarder,

In addition, in the above-described aspect, the semi-transparent concave mirror portion, the translucent concave mirror, the transparent glass plate provided on the exit surface side of the semi-transparent concave mirror, the first λ/4 second λ/4 having properties opposite to the retarder A phase retarder, a reflective polarizing plate, and a second absorbing polarizing plate having opposite properties to the first absorbing polarizing plate are sequentially included.

In addition, in the above-described aspect, the ambient light outside the light source is changed to linear polarization by the second absorption polarizing plate, and the linear polarization changes to circular polarization while passing through the second λ/4 phase delay through the reflective polarizing plate. Reflected by the semi-transparent concave mirror, the polarization direction is changed to linear polarization rotated by 90 degrees through the second λ/4 phase retarder, and the linear flat light whose polarization direction is rotated 90 degrees is blocked by the second absorption polarizer again. It will not come out.

In the above-described aspect, the angle of deflection of the light beam from the optical deflector to the microlens array is determined in order to remove spherical aberration caused when an image is formed on a stereoscopic image display area reflected from a translucent concave mirror.

At this time, the deflection angle of the light beam from the optical deflector to the microlens array is a direction given to a plurality of points forming an aberration correcting cone consisting of a plurality of points having virtual spatial coordinates that are symmetrical about an optical axis of the concave mirror. It is decided to match.

In addition, according to another aspect of the present invention, a method of forming an aberration correction cone used to correct an aberration of an image projected on an image display area positioned in front of a translucent concave mirror through a translucent concave mirror is provided. Specifically, this method

a) selecting one point P in the air in the image display area;

b) setting a connecting line connecting the selected point P and the center point O of the translucent concave mirror, wherein the connecting line becomes the optical axis z of the translucent concave mirror;

c) setting the origin o of the coordinate system near the position of the person observing the image display area, where the origin o is located on the optical axis z;

d) generating a small circle (c) having a predetermined diameter centered on the y axis perpendicular to the optical axis (z) at the origin o;

e) placing a plurality of points at equal intervals around the small circle (c);

f) Assume that the ray starts from the points set around the small circle (c), connect the P points at a plurality of points around the small circle c, and extend the line further to converge the lines reflected by the translucent concave mirror Calculating the points C to be;

g) calculating the vertical distance from the ray (or centerline) originating from the origin (or centerline) of the small circle c to the ray originating from a plurality of points around the small circle c, where the sum of the distances (rms value) This smallest point is selected as a single point forming an aberration cone-;

h) Repeating steps f) and g) by discontinuously changing the center of the circle on the y-axis at equal intervals on the y-axis, a curve (CL) consisting of points (C) on the front space of the translucent concave mirror surface. Obtaining a; And

i) obtaining the aberration correcting cone having a cone shape by rotating the curve CL obtained in step h) about the z axis;

j) giving the direction of the light beam to each point forming the aberration correcting cone, where the light beam direction is the direction of the light beam from the center of the small circle c reaching the aberration cone;

According to the present invention, as the convergence-adjustment distance is matched, the dizziness, eye fatigue, and vomiting caused by the mismatch are not caused even after viewing the stereoscopic image for a long time, and accordingly, the stereoscopic image that can be naturally perceived by the human eye It is possible to provide a display device.

In addition, according to the present invention, as a stereoscopic image is implemented through a relatively simple structure, a natural moving image such as holography can be implemented at a relatively low cost.

1A is a diagram for explaining the concept of convergence.
1B is a view for explaining the concept of adjustment or focus (Accommodation).
Figure 1c (a) shows the convergence-regulating state of the human eye in a normal situation. Figure 1c (b) schematically shows the convergence-regulation mismatch condition in the human eye
2 shows an example of a stereoscopic image display device manufactured to have the same convergence distance and adjustment distance according to the present invention.
3 is a view showing a collimating lens for changing the light of a laser diode to parallel light.
4 is a diagram showing an example of an acoustic light modulator.
5 is a view showing an example of an acoustic optical deflector.
6 is a view showing an example of light deflection using a galvanometer mirror.
7 shows an example of an f-θ lens.
8 is a view showing a main configuration of an optical unit according to an embodiment of the present invention.
9 is a view for explaining the function of the microlens array.
10 is a view for explaining the function of a small lens that converts diffused light into parallel light.
11 is a view for explaining optical aberration of light passing through the optical section.
12A is a view showing an example for correcting the optical aberration of FIG. 11;
12B is a view showing another example for correcting the optical aberration of FIG. 11;
13 is a view for explaining an image enlargement unit.
14 is a view for explaining the light from the optical unit is displayed on the image display area through the image enlargement unit.
15 is an explanatory diagram for explaining a method of converging the image to the focal point P2 through the translucent concave mirror of the image enlargement unit.
16 is a view showing an aberration correction cone.
Fig. 17 is a view showing a direction of light rays applied to an aberration correction cone.
18 is a diagram showing an example of light rays input from a small lens to an aberration correction cone.
19 is a view for explaining that the light with the aberration removed through an aberration correction cone is formed on a stereoscopic display image.
20 is a view showing various embodiments of a stereoscopic image display device according to the present invention.
21 is a view showing another embodiment in which a virtual image of a translucent concave mirror is visible.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms.

This embodiment in the present specification is to provide a complete disclosure of the present invention, and to fully inform the scope of the invention to those skilled in the art to which the present invention pertains. And the present invention is only defined by the scope of the claims. Thus, in some embodiments, well-known components, well-known operations, and well-known techniques are not specifically described in order to avoid obscuring the present invention.

The same reference numerals refer to the same components throughout the specification. In addition, the terms (mentioned) used in this specification are for describing the embodiments and are not intended to limit the present invention. In the present specification, the singular form also includes the plural form unless otherwise specified in the phrase. Also, components and actions recited as “includes (or is provided with)” do not exclude the presence or addition of one or more other components and actions.

2 shows an example of a stereoscopic image display device manufactured to have the same convergence distance and adjustment distance according to the present invention. The embodiments described below are merely illustrative of the technical spirit of the present invention, and those skilled in the art to which the present invention pertains can make various modifications and variations without departing from the essential characteristics of the present invention. Can understand.

As shown in FIG. 2, the stereoscopic image display device according to the present invention is controlled by a light source 100 for generating light, a dimming unit 200 for controlling the intensity and direction of light from the light source, and a dimming unit It includes an optical unit 400 for focusing the focused light on any one point or focal plane P1 located on the optical axis.

The light source 100 includes one or more laser diodes, and a laser beam is generated from the laser diodes. The number of light sources 100 may be appropriately selected according to the type and performance of the dimming unit 200 provided at the rear end of the light source unit.

The dimming unit 200 receives light from a laser diode, which is a light source 100, and modulator 210 for determining the intensity of light and a deflector 230 for deflecting the direction of light output from the modulator 210 ), and further provides a collimating lens for collimating the laser from the light source to the modulator 210 between the light source 100 and the modulator 210 to reduce the loss of the laser output from the light source as needed. It may be. The collimating lens acts so that light diverged from the laser diode is input into the modulator 210 in parallel as shown in FIG. 3. However, in another embodiment, the laser beam may be entered into the modulator 210 by focusing on any one point so that the width of the laser beam is adjusted as necessary.

More specifically, the modulator 210 may use various modulation techniques currently known to control the intensity of light from the laser diode, and the following may be used.

-Direct Modulation: Direct modulation is a method of adjusting the intensity of the laser output by changing the current input to the laser diode. It is slow, but the cheapest in terms of cost.

-External Modulation:

As an external modulation method, either an acoustic optic modulator or an electro-optic modulator may be used. In this method, the intensity of light emitted from the laser diode is constant, but the intensity of light is adjusted by using an acoustic light modulator or an electronic light modulator as a switch. 4 is a view showing an example of an acoustic light modulator that is one of the external modulation methods that can be used in the present invention, the present invention is not limited thereto, and an acoustic light modulator having another additional configuration may be used, and acoustic The optical modulator may use the same known technology, which is obvious to those skilled in the art, so a detailed description thereof will be omitted.

The light modulated through the modulator 210 is deflected through a deflector provided at the rear end of the modulator 210 and is incident on the optical unit 400 for imaging the image at the focal point P1.

The deflector 230 is a 2D deflector that deflects light on the x-axis and y-axis spaces, and the following may be used.

-Acousto Optic Deflector or Electro Optic Deflector: Acoustic optical deflector or electron optical deflector is suitable when the number of laser diodes used as a light source is small. 5 is a view showing an example of an acoustic optical deflector that can be used as a deflector. Acoustic optical deflectors may be used in the same manner known in the art, which is obvious to those skilled in the art, so a detailed description thereof will be omitted.

-Polygon Mirror or Galvanometer Mirror: A plurality of laser diodes or laser diode arrays are subjected to direct modulation as described above to change the light intensity and then polygon mirrors or galvanometers. The laser beam is scanned using a meter mirror.

6 is a diagram illustrating deflection of light using a galvanometer mirror as an example. In the method of deflecting light using a galvanometer mirror, as the number of laser diodes increases as shown in FIG. 6, the angle at which the laser beam is scanned becomes smaller.

On the other hand, when using an acoustic optical deflector or an electronic optical deflector, scanning is performed with a small number of laser diodes, preferably one laser diode, but when a polygon mirror or a galvanometer mirror is used, a large number of laser diodes are used. Since the scanning angle of the polygon mirror or the galvanometer mirror can be reduced very small, compared with the use of an acoustic optical deflector or an electronic optical deflector, a relatively slow scan speed can be compensated and at the same time, a lot of cost advantages can be taken.

Light that has passed through the optical deflector 230 is incident on the focal plane P1 to the optical unit 400 that forms an image. Incidentally, in the stereoscopic image display apparatus according to the present invention, light emitted from the optical deflector 230 between the optical deflector 230 and the optical unit 400 is a light incident surface S1 of one optical unit 400. In order to be uniformly incident on the f-θ lens 300 may be further included. The f-θ lens 300 may be installed as needed depending on the distance between the optical deflector 230 and the optical unit 400.

As shown in FIG. 7, the f-θ lens 300 causes the deflected light to converge on one coplanar plane S1 perpendicular to the optical axis. On the other hand, when the angle at which the light is deflected as the optical deflector is small, the concave lens may be inserted between the f-θ lens and the light incident surface S1 to increase the deflection angle.

Subsequently, the light that has passed through the f-θ lens 300 travels along the optical axis and enters the optical unit 400. 8 is a view showing the aforementioned main configuration of the optical unit 400 according to the present invention. As shown, the optical unit 400 performs an image forming function on the focal plane P1. To this end, the optical unit is a micro lens array 410, a small lens 430 composed of a plurality of small lenses, one It includes a large lens 450.

9 is a view for explaining the function of the microlens array 410, the microlens array 410 functions to diffuse light, the pitch of the microlens and the radius of curvature of one side of the lens is about several tens of μm. As shown, the micro lens array 410 diffuses the incident light beam to make it uniform.

As described above, the light passing through the micro lens array 410 passes through the small lens 430 installed at the rear end of the micro lens array 410 on the optical axis, where the small lens 430 diffuses as shown in FIG. 10. The converted light is converted into parallel light in a substantially parallel state. The diameter of a small lens is about a few millimeters. The larger the number of such small lenses, the more detailed the stereoscopic image can be. If a smaller number of lenses are used, preferably a single laser diode needs to scan only one small lens area corresponding to the same number. Therefore, the image quality is improved.

Thereafter, the light passing through the small lens enters through the large lens 450 provided at the rear end, and the light passing through the large lens 450 converges on the focus P1 again, thereby realizing a stereoscopic image. However, since the large lens 450 has a relatively large spherical surface compared to the small lens 430, spherical aberration is generated from the spherical surface as shown in FIG. That is, the position of the converging points varies depending on the position diffused in the microlens array 410 and the relative position of the small lens 430, and does not converge on one point P1 as shown in FIG.

In order to solve this, it is possible to consider forming the spherical surface of the large lens 450 as an aspherical surface, however, when a lens having a relatively large spherical surface is manufactured as an aspherical surface, the unit cost is too high. The present inventors converge the light coming from the small lens to one point by adjusting the position and angle of the small lenses 430 to solve the problem of not converging to one point due to spherical aberration generated from the large lens 450 as described above. Made it. This principle is illustrated in FIGS. 12A and 12B.

First, as illustrated in FIG. 12A, the positions of the plurality of small lenses are adjusted so as not to be in the same single plane to reduce spherical aberration of the large lens 450. That is, the light exit surface of the small lens 430 and the light incident surface of the large lens 450 are positioned relatively close to the central portion of the large lens 450 or the vicinity of the optical axis x, while the smaller the farther away from the optical axis the vertical direction is. The light exit surface of 430 and the light entrance surface of the large lens 450 are arranged to be further away radially.

In addition, as shown in FIG. 12B, the positions of the plurality of small lenses are adjusted so as not to be in the same single plane to reduce spherical aberration of the large lens 450, that is, the center of the large lens 450 or the optical axis x. In the vicinity, the light exit surface of the small lens 430 and the light entrance surface of the large lens 450 are positioned relatively close, while the distance from the optical axis in the vertical direction increases the light exit surface of the small lens 430 and the large lens 450 ), the light incidence surface is disposed radially further away, and in addition, the optical axes of the small lenses 430 are inclined with respect to the optical axis x of the large lens 450. At this time, the inclination angle formed by the optical axis of the small lenses 430 and the optical axis of the large lenses 45 is larger as the distance from the optical axis X of the large lens becomes larger and smaller as it is closer to the optical axis X.

According to this configuration, a relatively small volume (3cm*3cm*1.5cm: horizontal (x), vertical (y), height (z)) of three-dimensional images was obtained on the convergence point P1, and the convergence and adjustment distance were the same. Although the convergence-control mismatch problem as described above does not appear, this stereoscopic image has a small volume and needs to be enlarged.

13 shows an image enlargement unit 500 that is additionally provided near the focal plane P1, and more specifically, between the large lens 450 and the focal plane P1. The image enlargement unit 500 displays a stereoscopic image of light from a Fresnel Lens 510 and a Fresnel Lens 510 having a function of changing a direction toward a position of a person who sees light converging from a large lens. And a translucent concave mirror portion 520 converging to the second focal region P2 which is the region.

More specifically, the Fresnel lens unit 510 includes a Fresnel lens 511 and a first absorption polarizing plate 513 and a first λ/4 phase retarder provided on the exit surface side of the Fresnel lens 511. The transparent glass plate 522 provided on the exit surface side of the translucent concave mirror 521 and the translucent concave mirror 521 is included in order toward the translucent concave mirror part 520. ), a second λ/4 phase delayer 523 having a property opposite to that of the first λ/4 phase retarder (fast axes are perpendicular to each other), a reflective polarizer 525, and a second absorption type The polarizing plates 527 are sequentially included.

According to this configuration, the light passing through the Fresnel lens 511 first passes through the first absorption polarizing plate 513 and is changed to linear polarization (first linear polarization), and the linearly polarized light is the first λ/4 It is changed to circularly polarized light (first circularly polarized light) through the phase retarder 515 and is incident on the incident surface s1 of the translucent concave mirror 521.

Since the translucent concave mirror 521 has a translucent property, only about half of the incident light passes through the translucent concave mirror 521 and passes through the glass plate 522 to pass through the second λ/4 phase delayer 523. The second λ/4 phase delay 523 has properties opposite to the first λ/4 phase delay 515, for example, the first λ/4 phase delay 515 has an x-axis fest (x− In the case of a fast, y-slow delay, the second λ/4 phase delay 523, on the contrary, uses a y-axis fast (x-slow, y-fast) delay. Therefore, the light passing through the second λ/4 phase delayer 523 is changed to linear polarization (first linear polarization) having the same properties as the previous linear polarization.

Light that is linearly polarized through the second λ/4 phase retarder 523 (first linear polarization) meets the reflective polarizing plate 525. The reflective polarizing plate 525 is provided to have a property of reflecting all the light passing through the second λ/4 phase delayer 523. For example, if the linearly polarized light in the second λ/4 phase delayer 523 is an x-axis component of light on the orthogonal x-axis and y-axis, the reflective polarizer 525 emits light of the y-axis component of the light. It has the properties of a reflective polarizer that passes and reflects the x-axis component. Conversely, if the light linearly polarized in the second λ/4 phase delayer 523 is a component of the y-axis on the x-axis and y-axis orthogonal to each other, the reflective polarizer 525 passes light of the x-axis component and transmits the y-axis component. It has the characteristics of a reflective polarizing plate that reflects.

Therefore, light that is linearly polarized again after the second λ/4 phase delayer 523 (secondary linear polarization) is reflected on the reflective polarizer 525 and passes through the second λ/4 phase delayer 523 again. Is changed to circular polarization (second circular polarization) (at this time, circularly polarized light is delayed by λ/4 phase).

The second circularly polarized light passes through the glass substrate and meets the semi-transparent concave mirror 521, so that the half disappears and the other half returns, and the returned second circularly polarized light passes through the second λ/4 phase retarder 523 again. Thus, the specific component is delayed by λ/4 and linearly polarized. At this time, the linearly polarized light becomes the second linearly polarized light whose first polarization is rotated 90 degrees. The second linearly polarized light rotated in this way encounters the next reflective polarizing plate 525, but passes through the reflective polarizing plate 525 because the direction of polarization entering is rotated 90 degrees.

Thereafter, the second linearly polarized light passes through the second absorption type polarizing plate 527, and for this purpose, the second absorption type polarizing plate has different absorption characteristics from the first absorption type polarizing plate. For example, when the first absorption-type polarizing plate 513 absorbs the x-axis component of light and has polarization characteristics that pass through the y-axis component, the second absorption-type polarizing plate 527 passes the y-axis component of light and the x-axis component Has the property of absorbing. Therefore, the second linearly polarized light rotated 90 degrees from the first linearly polarized light can pass through the second absorption type polarizing plate 527 as it is.

According to this configuration, the object from which light starts through the translucent concave mirror 521 is as if it is in front of the concave surface of the translucent concave mirror and the actual image of the object is generated in front of the translucent concave mirror. However, the place where the light actually converged is behind the concave surface of the translucent concave mirror (near the Fresnel lens). In other words, the object from which the light actually originates becomes invisible to the viewer.

In addition, another function of the second absorption type polarizing plate 527 is to prevent the ambient light entering from the outside to be reflected again. That is, the external ordinary light is changed to linear polarization by the second absorption polarizing plate 527, and the linear polarization becomes circular polarization while passing through the second λ/4 phase delayer 523 through the reflective polarizing plate. In addition, when the second λ/4 phase retarder 527 is reflected by the translucent concave mirror 521, the polarization direction is changed to linear polarization rotated by 90 degrees. The linearly polarized light in which the polarization direction is rotated by 90 degrees is eventually blocked by the second absorption type polarizing plate 527 so that it does not come out, so that the quality of the image formed can be improved.

14 is a view showing that light from the optical unit 400 is displayed on the image display area through the image enlargement unit 500. As illustrated in FIG. 14, the light reflected from the translucent concave mirror 520 of the image enlargement unit 500 converges to the image display area, and the image is enlarged and displayed. When the distance from the concave mirror 520 to the focus P of the image display area is 90 cm, and the distance from the focus P to the viewer is 90 cm, a three-dimensional shape of width*length*height of 15cm*15cm*30cm can be obtained. Could.

On the other hand, in the embodiment shown in FIG. 14, an enlarged stereoscopic image without convergence-adjustment mismatch problem was obtained through the image magnifier, but in this case, aberration due to the spherical surface of the concave mirror 521 occurs, so that the light beam at the focus P is accurately There is a new problem in that the image is not converged and the image displayed on the stereoscopic image display unit in the air is not displayed very cleanly.

Hereinafter, a method of correcting spherical aberration generated by the translucent concave mirror 521 will be described. 15 is an explanatory diagram for explaining a method of converging an image to a focal point P2 in the translucent concave mirror 521 of the image enlargement unit according to the present invention. As shown in FIG. 15, in order to obtain a clean image at the point P2, all light reflected from the translucent concave mirror 521 must be converged at the point P2. However, if it is assumed that light is emitted from one point of the virtual object, the spherical aberration of the translucent concave mirror does not converge at one point. In other words, in order for the image to converge on one point of P2, the virtual object points must be dispersed. This set of distributed virtual object points is defined as "aberration correction cones".

The method of making the aberration correction cone is as follows.

a) First, a point P2 is selected in the air in the image display area.

b) Connect this point P2 and the center point O of the translucent concave mirror. This connecting line becomes the optical axis of the translucent concave mirror. This optical axis is called the z-axis.

c) Set the origin o of the coordinate system near the viewer's location. The origin o is located on the optical axis z.

d) At the origin o, create a small circle c with a diameter of 4 mm (diameter of the human pupil) centered on the y axis perpendicular to the z axis.

e) Place a plurality of points at equal intervals around the small circle c. The more points that are arranged, the more accurate the result of the aberration correction, but in this embodiment, it is set to 16.

f) Assume that the light starts at points set around the small circle c. That is, the position where spherical aberration is to be corrected is tracked in the viewer's eye. By connecting the P2 points at the points around the small circle c and extending the line further, the lines reflected by the translucent concave mirror mostly converge at one point C. However, not all are gathered at exactly one point.

g) The ray from the origin (or center) of the small circle c is the centerline of the bundle of light entering the pupil. Calculate the vertical distance from this centerline to the ray starting at a plurality of points around the small circle c. The point with the smallest sum of these distances (rms value) is one point that forms the aberration cone.

h) Repeat steps f) and g), discontinuously changing the center of the circle on the y-axis at equal intervals on the y-axis. Through this operation, as shown in FIG. 15, it is possible to obtain a curve CL as indicated by a thick line on the space in front of the concave surface. However, since these curves CL are discontinuous points, values can be obtained at arbitrary positions by performing interpolation.

i) When the curve CL obtained in step h) is rotated about the z-axis, a cone-shaped aberration correction position (ie, aberration correction cone) as in FIG. 16 is obtained.

j) FIG. 17 shows the direction of the light rays applied to each point forming the aberration cone, wherein the direction of the light rays originating from each of the plurality of points reaches the aberration cone with light coming from the center of the small circle c It is the direction of the rays.

k) This aberration cone is a curve created by moving a small circle c on the y-axis, and this basic curve is interpolated by the cubic spline method. And the coefficients of the cubic equation in each section of the cubic spline are expressed as a function of the distance r of the P2 point (where r is the distance from the origin o to the P2 point on the optical axis, see Fig. 15). This r function is also interpolated by the cubic spline method.

The method of making the aberration correcting cone in this way assumes that all light reflected on the translucent concave mirror 521 accurately converges on the P2 point, and then the light reflected from the translucent concave mirror through the P2 point from the user's eye. This is a way to track back. Since each of the plurality of points forming the aberration cone has a unique direction to converge the light at one point P2, if the light is emitted with a small three-dimensional angle in the direction given to each of the points of the aberration cone, light converges at one point P2 I can do it.

Next, a method of correcting spherical aberration of the translucent concave mirror 521 using this aberration cone will be described.

a) First, as shown in Fig. 15, the point P2 where the rays converge is selected. If the distance r from the user's eye to the point P2 is known, the spatial coordinates forming the aberration cone having the directionality of light can be determined by the above-described method of making the aberration cone.

b) When the spatial coordinates of the aberration cone are determined, an aberration cone is formed on the opposite side of the translucent concave mirror as the reflective polarizing plate 525 attached to the translucent concave mirror 521 acts like a mirror. At this time, the light emission direction is given to each of the plurality of points forming the aberration cone.

c) As shown in FIG. 18, the light entering the translucent concave mirror 521 converges from the small lenses 430. Among the points forming the aberration cone and the center line of the converging light, the point of the aberration cone whose direction is the same Only fields are selected. The light coming from the small lenses 430 does not have to converge accurately on the aberration cone, but only needs to match the direction, because such an error does not significantly affect the creation of a stereoscopic image.

d) As in step c), when the points having the same direction among the points of the aberration cone are determined, it may be determined where the laser beam entering the small lens 430 diffuses in the microlens array 410.

e) After the diffusion position of the microlens array 410 is determined, the deflection angle of the light beam from which the light departing from the deflector 230 enters the diffusion position is determined, and it is necessary to accurately enter the light beam into the diffusion position. Voltage is applied to the deflector 230.

This means that the light converging by each small lens 430 is responsible for a small three-dimensional angle, and they gather to form a light bundle having a larger three-dimensional angle. Within the three-dimensional angle of this bundle of light, there is no empty space, and it becomes dense. Even if only points where light coming from converging from a small lens coincides with the direction of the aberration cone, the light bundle is tightly compacted. The aberration cone is formed at point C as shown in Fig. 15. If the three-dimensional angle of this light bundle is small, the light spreading past this point C may not be directed to the position of the viewer.

However, as shown in FIG. 19, light from the microlens array 410 is incident on the translucent concave mirror 521 through the Fresnel lens 511, and the Fresnel lens 511 is formed near the point C. Since the aberration cone is turned to make the light advance toward the viewer, the light converges to the stereoscopic image display area on the way, and a three-dimensional image with spherical aberration removed is provided to the viewer.

Such a stereoscopic image display device may be implemented in various ways as shown in FIGS. 20A to 20C. FIG. 20(a) shows a stereoscopic image displayed in a horizontal direction, and FIG. 20(b) shows a stereoscopic image converted by a mirror after irradiating the stereoscopic image in the vertical direction. (c) shows an example in which a plurality of stereoscopic image display devices are viewed in a 360-degree viewing area using a cone mirror, and the present invention is not limited to these embodiments, and the scope of the claims is described. Other variations and modifications are possible within.

In the above-described embodiment, what has been described so far has been described only in the case where the real image is formed by the translucent concave mirror, but adjusting the position of the image formed on P1, that is, moving it into the focal length of the translucent concave mirror is shown in FIG. You can also create a stereoscopic image by using a virtual image like you did.

According to the above-described embodiment of the present invention, as the convergence-adjustment distance is matched, dizziness, eye fatigue, and vomiting caused by the mismatch are not caused even after viewing a stereoscopic image for a long time, and thus naturally perceived by the human eye A stereoscopic image display device that can be provided can be provided, and as a stereoscopic image is implemented through a relatively simple structure, a natural image such as holography can be implemented at a relatively low cost.

The above description is merely illustrative of the technical spirit of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are for illustrative purposes, not for limiting the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments.

Therefore, the protection scope of the present invention should be interpreted by the following claims rather than limited by the above-described embodiments, and all technical spirits within the equivalent ranges should be interpreted as being included in the scope of the present invention.

100: light source or laser diode 200: dimming unit
210: optical modulator 220: optical deflector
300: f-θ lens 400: optical
410: micromirror array 430: small lens
450: large lens 500: image magnification
510: Fresnel lens unit 511: Fresnel lens
513: first absorption polarizer 515: first λ/4 phase retarder
520: translucent concave lens portion 521: translucent concave lens
522: glass substrate 523: second λ/4 phase retarder
525: reflective polarizer 526: second absorption polarizer

Claims (12)

In the stereoscopic image display device having the same convergence distance and adjustment distance,
One or more light sources 100 for irradiating stereoscopic content;
A dimming unit 200 for adjusting the intensity and direction of light from the one or more light sources; And
And an optical unit 400 that receives the controlled light from the dimming unit and forms an image of a stereoscopic image at a point P1 on the optical axis, and displays the image.
The optical unit 400,
Microlens array 410 that diffuses the incident light and transmits it to a small lens array 430 at the rear end,
A small lens array 430 composed of a plurality of small lenses, each of which is a small lens array 430 that converts light transmitted from the micro lens array 430 into parallel light,
And one large convex lens 450 for imaging the parallel light transmitted from the small lens array 430 at a point P1 on the optical axis,
Characterized in that the distance from the light exit surface of the small lens array 430 to the light entrance surface of the large convex lens 450 increases as the distance from the optical axis increases.
A stereoscopic image display device having the same convergence distance and adjustment distance.
According to claim 1,
The dimming unit 200,
Light modulator 210 for adjusting the light intensity and
Characterized in that it comprises a light deflector 230 for adjusting the direction of the light
A stereoscopic image display device having the same convergence distance and adjustment distance.
According to claim 2,
The light source is one or more laser diodes,
The optical modulator 210 is modulated through a direct modulation method that directly changes the current input to the laser diode, or includes any one of an acoustic optic modulator and an electro-optic modulator. Characterized by being modulated by an external modulating device
A stereoscopic image display device having the same convergence distance and adjustment distance.
According to claim 3,
The light source is one or more laser diodes,
The optical deflector 230 is a 2D deflector that deflects modulated light in two-axis spaces on the x-axis and the y-axis,
The optical deflector 230 is selected from the group consisting of an acoustic optical deflector, an electronic optical deflector, a polygon mirror, and a galvanometer mirror. Characterized by
A stereoscopic image display device having the same convergence distance and adjustment distance.
delete delete According to claim 1,
The stereoscopic image display device,
To enlarge the image formed on the point P1 further includes an image enlargement unit 500 in the vicinity of P1,
The image enlargement unit 500,
The Fresnel Lens unit 510 which changes the direction of the light converging from the convex lens 450 to the point P1 toward the position of the viewer
And a translucent concave mirror unit 520 converging light from the Fresnel lens unit 450 to a point P2 that is a stereoscopic image display area.
A stereoscopic image display device having the same convergence distance and adjustment distance.
The method of claim 7,
The Fresnel lens unit 510 includes a Fresnel lens 511, a first absorption polarizing plate 513 coupled to the exit surface side of the Fresnel lens 511, and a first λ/4 phase retarder 515 ) In turn,
The translucent concave mirror portion 520 is a translucent concave mirror 521, a transparent glass plate 522 provided on the exit surface side of the translucent concave mirror 521, opposite to the first λ/4 phase retarder A second λ/4 phase delayer 523 having properties, a reflective polarizing plate 525, and a second absorbing polarizing plate 527 having properties opposite to those of the first absorbing polarizing plate 513, are sequentially included. Characterized by
A stereoscopic image display device having the same convergence distance and adjustment distance.
The method of claim 8,
The ambient light outside the light source is changed to linear polarization by the second absorption polarizing plate 527, and the linear polarization passes through the second λ/4 phase delayer 523 through the reflective polarizing plate 525. It is changed to circularly polarized light and reflected by the translucent concave mirror 521 to pass through the second λ/4 phase retarder 527 to change to linearly polarized light whose polarization direction has been rotated 90 degrees, and the polarization direction has been rotated 90 degrees. The flat light is blocked by the second absorption type polarizing plate 527, so that it does not come out again and the quality of the image formed is improved.
A stereoscopic image display device having the same convergence distance and adjustment distance.
The method of claim 8,
It is characterized in that the angle of deflection of the light beam from the optical deflector 230 to the microlens array is determined in order to remove spherical aberration generated when an image is formed on a stereoscopic image display area reflected by the translucent concave mirror 521. To do
A stereoscopic image display device having the same convergence distance and adjustment distance.
The method of claim 8,
The deflection angle of the light beam from the optical deflector 230 to the microlens array is
Characterized in that it is determined to coincide with a direction given to a plurality of points forming an aberration correcting cone consisting of a plurality of points having virtual spatial coordinates symmetrical about an optical axis of the concave mirror.
A stereoscopic image display device having the same convergence distance and adjustment distance.
A method of forming an aberration correction cone used to correct an aberration of an image projected on an image display area positioned in front of a translucent concave mirror through a translucent concave mirror,
a) selecting one point P2 in the air in the image display area;
b) setting a connecting line connecting the selected point P2 and the center point O of the translucent concave mirror, wherein the connecting line becomes the optical axis z of the translucent concave mirror;
c) setting the origin o of the coordinate system near the position of the person observing the image display area-the origin o is located on the optical axis z-;
d) generating a small circle (c) having a predetermined diameter centered on the y axis perpendicular to the optical axis (z) at the origin o;
e) placing a plurality of points at equal intervals around the small circle (c);
f) Assume that the ray starts at the points set around the small circle (c), connect the P2 points at multiple points around the small circle c and extend the line further to converge the lines reflected by the translucent concave mirror Calculating the points C to be;
g) calculating the vertical distance from the ray (or centerline) originating from the origin (or centerline) of the small circle c to the ray originating from a plurality of points around the small circle c, where the sum of the distances (rms value) This smallest point is selected as a single point forming an aberration cone-;
h) Repeating steps f) and g) by discontinuously changing the center of the circle on the y-axis at equal intervals on the y-axis, a curve (CL) consisting of points (C) on the front space of the translucent concave mirror surface. Obtaining a; And
i) obtaining the aberration correcting cone having a cone shape by rotating the curve CL obtained in step h) about the z axis;
j) giving the direction of the light beam to each point forming the aberration correcting cone, where the light beam direction is the direction of the light beam from the center of the small circle c reaching the aberration cone-including; Characterized by
A method of forming an aberration correction cone used to correct an aberration of an image projected on an image display area positioned in front of a translucent concave mirror through a translucent concave mirror.

Images