KR102135748B1 - Apparatus for guiding optical wave paths - Google Patents

Abstract

The present invention relates to a light path control device.
Specifically, the light path control device outputs light of uniform intensity enlarged to a size corresponding to the active area of the display by using the characteristics of the incident wave length of the coherent light beam.

Description

Light path control device {APPARATUS FOR GUIDING OPTICAL WAVE PATHS}

The following description relates to a light path control device, and more particularly, to a light path control device that controls a light path for illumination inserted into a display device.

The holographic display technology is a three-dimensional display of objects, which is an ideal full-reality three-dimensional display technology. Specifically, the hologram display technology is a technology that gives the same effect as the actual existence of the object in the human eye as the wave-front generated by the given object is reproduced as it is. In the conventional holographic display technology, as the images corresponding to the left and right eyes are differently expressed according to the movement of the eyes, symptoms of eye fatigue and dizziness caused by parallax occurred.

In recent years, as the 3D display technology has developed, by expressing objects with perfect parallax and depth, there are no symptoms of eye fatigue and dizziness caused by the problem of accommodation-convergence mismatch. Furthermore, the holographic display technology has evolved to the ultimate three-dimensional display technology capable of observing different images according to the movement of the viewpoint and enabling multiple viewing without the need for ancillary devices (eg glasses) for viewing. . However, there are several requirements to implement such a holographic display technology.

First, the holographic display technology requires a display device to express an image having a wide viewing angle. In other words, the holographic display technology is expressed by an image having a wide viewing angle, and for this purpose, a display display element having a size of a pixel pitch of a wavelength of visible light (1 um or less) is required.

Second, the holographic display technology requires a display area of more than one level to reproduce a holographic image. In other words, the holographic display technology needs to reproduce a holographic image of a sufficient size according to an image. Therefore, the display area of the spatial light modulator should have an active area size of a certain level or more (2 inches or more). To this end, recently, a technique for expanding the size of a holographic panel by tiling a small panel has been introduced.

However, such a tiling structure has a problem in that the hologram image reproduced by the presence of the seam boundary lines deteriorates the hologram image quality reproduced by the black lines resulting from the boundary lines. On the other hand, since the range of the holographic image size and viewing angle that can be expressed only with currently available display elements is very small, the characteristics of the holographic display as an ideal 3D display (movement parallax, control-runaway match, binocular parallax) are actually observed. Is not easy.

Therefore, many studies have been conducted to overcome the limitations by combining additional optical and mechanical control systems with display elements. However, this type of system takes up a large amount of space and requires an optically precise alignment process. The big disadvantage is that even if a holographic display system is actually implemented, it is not easy to move due to the bulky system structure. In addition, the holographic display mainly uses an illumination light source having coherence such as a laser. Since it is dangerous to directly see such illumination light for a long time with eyes, most of the camera shooting is performed to prepare an optimal image. Occasionally, observation and viewing are only necessary indirectly.

Therefore, the coherent light having sufficient intensity must illuminate the active area of the spatial light modulator where the hologram is encoded with a uniform intensity. Furthermore, it is necessary to provide a holographic display made of a flat-panel lighting device to include the display active area while having as small a thickness and light weight as possible in such a holographic image reproduction system.

The present invention can provide a planar light path control device having a minimum thickness in which light having coherence is illuminated with a uniform intensity in an active area of a display such as a spatial light modulator.

According to one embodiment, the light path control device is a first light guide plate to which a light beam output from a light source is incident-the light beam is incident on the injection surface of the first light guide plate at a first incident angle, and transmitted at a first transmission angle being-; A first grating through which the light incident on the first light guide plate is transmitted to the interior of the second light guide plate, wherein the light transmitted through the first grating is a first incident angle corresponding to the first transmission angle on the grating surface of the first grating. Is incident, and is transmitted into the second light guide plate at the second transmission angle-; A second light guide plate through which the light transmitted through the first grating passes through and enters the second grating, wherein the light passing through the second light guide plate is determined according to the second transmission angle and the refractive index of the second light guide plate; And a second grating through which the light passing through the second light guide plate is incident, and a light incident on the second grating is output in a direction perpendicular to one surface of the second grating.

According to an embodiment, the incident light beam may be incident in a P-polarized state with respect to the injection surface in consideration of the surface reflectivity generated at the injection surface of the first light guide plate according to the refractive index of air.

According to one embodiment, the light transmitted through the first grating may be transmitted into the second light guide plate having the same refractive index as the refractive index of the first light guide plate according to the diffraction conditions of the first grating.

According to an embodiment, the first transmission angle may be determined by an incident angle of light incident on the first light guide plate, a grating direction of the first grating, and a grating period of the first grating.

According to one embodiment, the first grating is a first light guide plate and a second light guide plate bonded at a slope according to the transmission angle so that the light rays enter the interior of the second light guide plate in consideration of the relative fracture rate between the first light guide plate and the air Can connect.

According to an embodiment, the width of the light beam may be enlarged before and after passing through the first grating by the incident wave field of the light beam incident on the injection surface.

According to an embodiment, the transmitted light beam may have a wider width of light before and after passing through the second grating by the incident wave field of the light transmitted through the second light guide plate.

According to an embodiment, the output light is generated through an incident wave field having coherence, and may have a spatially homogeneous intensity.

According to one embodiment, the second grating is perpendicular to the light exit surface of the second grating in consideration of the incident angle of the light passing through the second light guide plate, wherein the incident angle of the light is determined by the second transmission angle and the refractive index of the second light guide plate. It may be connected to one surface of the second light guide plate to be output at an angle.

According to an embodiment, the display may be a flat-panel holographic display joined in parallel with the light exit surface of the second grating or spaced a certain distance.

The light path control device according to an embodiment illuminates light having coherence in a uniform intensity in an area sufficiently including an active area of a display such as a spatial light modulator, and simultaneously controls a flat type light path having a minimum thickness. By providing a device, a commercially available single modular flat panel holographic display system can be implemented.

1 is a view showing a light path control device and a display according to an embodiment.
2 is a view showing a side view and a front view of a light path control apparatus according to an embodiment.
3 is a view for explaining a path of a light beam incident to the light path control apparatus according to an embodiment.
4 is a graph for explaining a relationship between an incident angle of light and a reflectance at an injection surface of a first light guide plate according to an embodiment.
5 is a view for explaining the arrangement of a transmission type diffraction grating by periodic arrangement according to an embodiment.
6 is a view for explaining the arrangement of the transmissive grating by a periodic refractive index change according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a light path control device and a display according to an embodiment.

Referring to FIG. 1, the light path control device 101 may output light having a uniform intensity enlarged to a size corresponding to an active area of a display by using characteristics of an incident wave field of light having coherence. It may be a lighting device. For example, the light path control device 101 may be a small-sized laser module implemented as a slim style back light unit (BLU) or front light unit (FLU). In addition, the light path control device 101 may control the path to the incident light beam by including at least one optical component. That is, the light path control device 101 may control the path of the light beam in the direction in which the display 106 is located, enlarge the width of the light beam, and output it to the display 106.

In addition, the display 106 may display a stereoscopic image in space by modulating a light beam of uniform intensity output from the light path control device 101. Here, the light path control device 101 and the display 106 may be combined with each other in a single module form (not shown) or spaced apart at regular intervals to be implemented as a display system (not shown).

Specifically, the light path control device 101 may control the path of the light beam output from the light source in order to output the light beam to the display 106. To this end, the light path control device 101 may be incident with light rays to be output to the display 106. Here, the light beam may be incident on the light beam path control device 101 through the following steps.

In detail, the light beam may pass through a light condenser that collects the light output from the light source and makes it parallel. At this time, it is possible to indicate the characteristics of an incident wave field having coherence of light rays. In addition, the light beam passing through the light converging portion is a planar wavefront having distinguishable directivity, and may have a spatially uniform intensity.

Here, the light collecting unit may pass light emitted from the light source according to the light transmission principle. In other words, the light condensing unit may pass light having a P-polarization state in order to increase the incident efficiency of the light beam in consideration of the surface reflectivity generated at the light emitting surface of the light path control device 101.

At this time, the light path control device 101 may include a first light beam expanding unit and a second light beam expanding unit to enlarge the light beam path control and the light beam width according to the position of the display 106. The first light beam expander may include a first light guide plate 102 and a first grating 103, and the second light beam expander may include a second light guide plate 104 and a second grating 105. In addition, the first light beam expander and the second light beam expander may be disposed to face each other and have a geometric cross-sectional structure that is integrally joined.

The first light beam expanding unit may control a path of the light beam such that the light beam outputted from the light collecting unit is incident and the incident light beam is transmitted through the first grid to the inside of the second light guide plate 104. At this time, the light transmitted through the first grating can be transmitted to the interior of the second light guide plate by expanding the width of the light beam by the incident wave field.

In addition, the second light beam expander controls the path of the light beam so that light transmitted through the first light beam expander passes through the second light guide plate 104 and is output in the vertical direction to the display 106 through the second grating 105. Can. At this time, the light beam transmitted through the second grating 105 may be output to the display 106 by expanding the width of the light beam by the incident wave field.

Here, by controlling the diffraction conditions of the first grating and the second grating included in each of the first light expanding unit and the second light expanding unit, it is possible to control the path of the transmitted light. In one example, the first grating and the second grating may be gratings that satisfy the Bragg diffraction condition for a normal to the grating surface having a pitch of P.

As a result, the light path control device 101 may control the path of the light beam in the direction in which the display 106 is positioned according to the diffraction conditions of the grating included in the first light beam expansion unit and the second light beam expansion unit. In addition, the light path control device 101 corresponds to the active area of the display 106 as the width between the light beams is expanded by the incident wave field of the light beam as it is transmitted through the first grating 103 and the second grating 105 The incident wave length of the light beam can be enlarged to a desired size.

Then, the display 106 may receive a light beam enlarged to a size corresponding to the active area through the light beam path control device 101 and display a stereoscopic image.

2 is a view showing a side view and a front view of a light path control apparatus according to an embodiment.

Referring to (a) of FIG. 2, a side view of the light path control device may include a cross section of a first light guide plate, a first grating, a second light guide plate, a second grid, and a display. Hereinafter, the path of the light beam output from the light source will be described based on the side view of the light path control device.

The light beam output from the light source may be incident into the first light guide plate. At this time, the output light beam may be incident in a direction substantially perpendicular to the injection surface of the first light guide plate. Here, the output light beam may be incident almost perpendicularly to the injection surface 201 of the first light guide plate based on the front view of the light beam path control device shown in FIG. 2B. The injection surface 201 of the first light guide plate illustrated in FIG. 2B may correspond to the injection surface of the first light guide plate of FIG. 2A.

In addition, the incident angle of the light incident on the injection surface may satisfy the condition that the transmission angle becomes θ in consideration of the refractive index between the light guide plate and the air. Here, the transmission angle may be a condition for entering the interior of the second light guide plate through the first grating 103. More specifically, the first light beam expander and the second light beam expander may have different directions in which light rays are incident.

Accordingly, the first light beam expanding unit may be inclined and joined in the inner direction of the second light beam expanding unit so that light rays may enter the inside of the second light beam expansion unit. In this case, the inclination may be represented by a first transmission angle θ with respect to the first incident angle of the light incident on the injection surface of the first light guide plate constituting the first light expanding unit. Here, the first incident angle may mean an incident angle of light incident on the first light guide plate. Further, the first transmission angle may mean a transmission angle of light transmitted through the first light guide plate.

Therefore, the first light-expansion unit and the second light-expansion unit may be joined at a slope of (θ) according to the first transmission angle. Then, the light output from the light source is the first light guide plate that satisfies the condition that becomes the first transmission angle θ in consideration of the second angle of incidence of the first grating for entering the interior of the second light beam expansion unit. It can enter the injection surface.

In addition, by considering the relative refractive index between the refractive index of the first light guide plate and the refractive index of the air layer, the light beam output from the light source satisfies the condition that becomes the first transmission angle θ and can be transmitted through the injection surface of the first light guide plate. The first transmission angle may be determined by a first incident angle of light incident on the first light guide plate, a lattice direction of the first grating, and a lattice period of the first grating.

Then, the light incident on the first light guide plate may pass through the interior of the first light guide plate and be transmitted through the first grid to the interior of the second light guide plate. Here, light rays transmitted through the first grating may be transmitted at a second transmission angle with respect to the grating surface of the first grating. That is, in the first grating, the first transmission angle of the light incident on the first light guide plate is used as the second angle of incidence, so that the light passing through the first light guide plate can be transmitted to the interior of the second light guide plate at the second transmission angle.

Here, the first grating may be an optical component designed to control the path of the light beam as a diffraction grating through which the light beam may enter the interior of the light guide plate for the first transmission angle mentioned above.

The light beam transmitted through the first grating may pass through the second light guide plate to enter the second grating. Here, the light transmitted through the first grating is incident on the second grating at an incident angle, and the incidence angle may be determined according to the second transmission angle and the refractive index of the second light guide plate. As an example, the light beam transmitted through the first grating may enter the inside of the second light guide plate and have a φ angle with respect to one surface of the second light guide plate facing the second grating. Here, the Ф angle may satisfy a condition that can be output in the vertical direction to the display by the second grid.

The light path control device may enlarge the light beam width with respect to the incident wave field with respect to the light beam. Further, the second grating may be an optical component designed to control the path of the light beam as a diffraction grating that can be output toward the air layer or the display when the light beam passing through the second light guide plate has an incident angle Ф above. .

At this time, as the display displays the light beam output from the second grid as a stereoscopic image, the size of one surface of the second light guide plate and the second grid may be the same as the active area of the display.

As a result, the light output from the light path control device through the above-described process may have a characteristic of a plane wave field enlarged to a size corresponding to the active area of the display. At the same time, the light output from the light path control device may be characterized in that it has a uniform light intensity.

3 is a view for explaining a path of a light beam incident to the light path control apparatus according to an embodiment.

Referring to FIG. 3, in the light path control device, light rays may be incident on the injection surface 301 of the first light guide plate 302. Here, the incident light beam may be incident in the P-polarized state to the injection surface 301 in consideration of the surface reflectivity generated at the injection surface 301 of the first light guide plate 302 according to the refractive index of air.

Further, the incident light beam may be transmitted at a first transmission angle through the injection surface 301 of the first light guide plate 302. In addition, the incident light beam may pass through the first light guide plate 302 and be transmitted through the first grating into the second light guide plate 304. Here, the incident light beam may be transmitted to the interior of the second light guide plate having the same refractive index as that of the first light guide plate according to the diffraction conditions of the first grating. Further, the light beam passing through the second light guide plate is incident on the second grating at an incident angle, and the incident angle may be determined according to the transmission angle and the refractive index of the second light guide plate.

At this time, the light beam transmitted through the first grating 303 is compared to the width d1 of the light beam before passing through the first grating due to the incident wave length of the light incident from the injection surface 301 ( d2) can be enlarged. In other words, the light transmitted through the first grating 303 may pass through the second light guide plate 304 through a continuous light flow having a width different from the incident wave field of the light output from the light source. Therefore, the light beam passing through the second light guide plate 304 may be enlarged than the size of the wave field incident on the injection surface 301.

The light beam transmitted through the first grating may pass through the second light guide plate at the width d2 of the light beam and enter the second grating. In addition, the light beam incident on the two gratings 305 may be output in a direction perpendicular to one surface of the second grating. Here, the light transmitted through the second grating 305 is compared to the width d2 of the light before passing through the second grating 305 by the incident wave field of the light transmitted through the second light guide plate, and then transmitted. The width d3 of may be enlarged and output.

In addition, the light beam output through the second grating 305 may be transmitted to the display. Here, the display may be a flat-panel holographic display joined in parallel with the light exit surface of the second grating 305 or spaced a certain distance. In addition, the display may display a light beam having an enlarged size corresponding to the active area of the display as a stereoscopic image. As a result, the light path control device may enlarge the image to a size corresponding to the active area of the display by using the characteristics of the incident wave field of the light beam.

4 is a graph for explaining a relationship between an incident angle of a light ray and a reflectance at an injection surface of a first light guide plate according to an embodiment.

Referring to FIG. 4, when the light output from the light source is injected into the interior of the first light guide plate through the injection surface of the first light guide plate, the refractive index nA of the first light guide plate and the fracture index n0 of air may be considered. . When considering the fracture rate of the first light guide plate and the fracture rate of air, the relationship between the incident angle (Ф) and the transmission angle (θ) of the output light beam can be expressed as in Equation 1.

When the light beam output from the light source is based on Equation 1, a difference in reflectance as shown in FIG. 4 may occur depending on the polarization state of the light beam with respect to the injection surface of the first light guide plate. Here, the polarization state means light having a constant direction of the vibration surface of the electric field at the injection surface of the first light guide plate, and may be largely divided into an S polarization state and a P polarization state. The S polarization state means a waveform that vibrates horizontally on the injection surface of the first light guide plate, and may mean a state in which selective reflection is possible. The P polarization state means a waveform oscillating perpendicular to the S wave, and may mean a state in which selective transmission is possible.

In addition, the present invention may assume that light is incident from the air layer to the first light guide plate as a dielectric based on the polarization state. According to the assumption, the S polarization state and the P polarization state of the output light beam show a similar difference in reflectance by the first light guide plate when the incident angle (Ф) is within 10 degrees. However, the output light ray may always exhibit less reflectance by the first light guide plate in the P polarization state from 10 degrees or more.

That is, when the output light beam has a P polarization state from 10 degrees or more, it can be seen that the transmittance by the injection surface of the first light guide plate is improved. Here, the transmittance can be expressed as Equation (2).

Therefore, when the incident angle is large in order to increase the injection efficiency of the light into the first light guide plate, the light path control device may use light having a P polarization state. In particular, in the case of 70 to 90 degrees, the light path control device needs to separately consider a solution to suppressing reflection in order to lower the surface reflectance. Therefore, when considering the optimal light injection efficiency, the light path control device can design the incident angle of the light incident into the first light guide plate within 60 degrees.

In addition, the light path control device may arrange the first light beam expanding unit and the second light beam expanding unit to face each other in order to minimize the surface reflection phenomenon due to the change in the refractive index of the light beam. In other words, the light path control device may be arranged to face each other according to the transmission angle of the output light beam in order to minimize the surface reflection phenomenon caused by the light guide plate as light is injected from the first light beam expansion unit to the second light beam expansion unit.

In addition, the light path control device may be arranged so that the first and second light expanders face each other, and maintain the same refractive index between the first light guide plate and the second light guide plate. That is, the light path control device may provide consistency of refractive index values between dielectric materials by using a dielectric having the same refractive index for the first and second light guide plates. In addition, the light path control device may fundamentally solve a problem of light loss such as light leakage generated in the process of passing between the interface surfaces due to the existence of a conventional air gap according to the consistency of the refractive index values between dielectric materials. Moreover, it is possible to minimize the extra effort of performing precise alignment due to occurrence of positional shift or direction distortion between optical components.

5 is a view for explaining the arrangement of a transmission type diffraction grating by periodic arrangement according to an embodiment.

Referring to FIG. 5, the light path control device may include a first grating and a second grating. Here, the first grating and the second grating may mean a transmission type diffraction grating by periodic arrangement. Hereinafter, the first grating and the second grating are combined to be expressed as a transmission diffraction grating.

과

으로 주어질 수 있다. 그리고, 그레이팅의 하부 매질의 굴절률과 그레이팅의 상부 매질의 굴절률은 각각

과

으로 주어질 수 있다. 이 때, 그레이팅의 하부 매질과 상부 매질은 위에서 언급한 바와 같이 동일한 굴절률로 나타날 수 있다. 그리고, 그레이팅의 하부 매질과 상부 매질은 각각 본 발명에 구성된 제1 도광판 및 제2 도광판에 대응할 수 있다.In general, the transmission type diffraction grating can be formed of a material having a periodic slit arrangement structure or a periodic refractive index change. Specifically, the transmission type diffraction grating may be formed by grating having a pitch of P. At this time, the angle of incidence and the angle of transmission with respect to the normal 501 of the grating are respectively

and

Can be given as In addition, the refractive index of the lower medium of the grating and the refractive index of the upper medium of the grating, respectively,

and

Can be given as At this time, the lower medium and the upper medium of the grating may have the same refractive index as mentioned above. Further, the lower medium and the upper medium of the grating may respectively correspond to the first light guide plate and the second light guide plate configured in the present invention.

In addition, the difference between the path of the right ray 503 and the path of the left ray 502 may be expressed as Equation (3).

In addition, since the difference value between the paths of the light beams determined through Equation 3 should be an integer multiple of the wavelength of the diffracted light by grating, the m-th order diffracted light can be expressed as Equation 4.

Therefore, the transmission type diffraction grating used in the present invention can be expressed as Equation (5).

6 is a view for explaining the arrangement of the transmissive grating by a periodic refractive index change according to an embodiment.

Referring to FIG. 6, the light path control device may exhibit a minimum thickness for the first grating and the first grating due to a periodic change in refractive index. More specifically, the light path control device may include a first grating and a second grating. Here, the first grating and the second grating may mean a transmission type diffraction grating by periodic arrangement. Hereinafter, the first grating and the second grating are combined to be expressed as a transmission diffraction grating.

)과 투과각(

)으로 주어질 수 있으며, 입사각(

)과 투과각(

)은 반사의 법칙에 의해 각각

으로 주어질 수 있다.The transmission diffraction grating has an angle of incidence relative to the normal to the surface of the grating with the pitch P

) And transmission angle (

), the angle of incidence (

) And transmission angle (

), respectively, by the law of reflection

Can be given as

과

으로 주어질 수 있다. 여기서, 투과형 회절 격자에서 사용되는 투과광의 진행 방향은 Bragg grating 회절 조건에 의해서 수학식 6과 같이 나타낼 수 있다.In addition, when the refractive index of the grating is n, in general, the refractive index of the lower medium of the grating and the refractive index of the upper medium of the grating, respectively,

and

Can be given as Here, the traveling direction of the transmitted light used in the transmission type diffraction grating can be expressed as Equation 6 by Bragg grating diffraction conditions.

이라고 가정할 수 있다. 즉, 투과형 회절 격자에서 투과된 광선의 방향은 광선의 입사각, 격자 방향 및 격자 주기에 의해 결정될 수 있다.And, based on the equation (6), the refractive index of the upper medium and the lower medium to the refractive index of the grating is

Can be assumed. That is, the direction of the light beam transmitted from the transmission type diffraction grating may be determined by the incident angle of the light beam, the grating direction, and the grating period.

As a result, the ray path control apparatus can control the path of the ray in a desired direction by designing grating in consideration of the incident angle of the ray, the grating direction, and the grating period. Furthermore, the light path control device may improve the diffraction efficiency of transmitted light by designing the thickness of the transmission type diffraction grating to have a sufficient thickness (d) of about 10 um. In addition, the light path control device can provide high angular selectivity as it has a minimized thickness d. That is, the light path control device has excellent angle selectivity due to small angular divergence characteristics.

Therefore, the light control device proposed in the present invention may be designed to use a transmission diffraction grating by a periodic refractive index change that can provide high light transmission efficiency and high angular selectivity to output light.

Devices according to an embodiment of the present invention may be recorded in a computer readable medium by being implemented in the form of program instructions that can be executed through various computer means. The computer-readable medium may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the present invention or may be known and usable by those skilled in computer software.

As described above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited to the above embodiments, and various modifications and variations from these descriptions will be made by those skilled in the art to which the present invention pertains. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims to be described later, but also by the claims and equivalents.

101: light path control device
102: first light guide plate
103: first grid
104: second light guide plate
105: second grid
106: display

Claims (20)

A first light guide plate through which light beams output from a light source are incident, wherein the light beam is incident at an injection surface of the first light guide plate at a first incident angle and transmitted at a first transmission angle; and bonded to the first light guide plate to A first grating through which the light incident on the first light guide plate is transmitted to the interior of the second light guide plate-The light transmitted through the first grating is a second incident angle corresponding to the first transmission angle on the grating surface of the first grating. A first light beam expanding unit including; incident to and transmitted into the second light guide plate at a second transmission angle; And
A second light guide plate through which light transmitted through the first grating passes through and enters the second grating, wherein light rays passing through the second light guide plate are determined according to the second transmission angle and the refractive index of the second light guide plate; and the first 2 A second light beam enlargement unit including a second grating joined to the light guide plate and through which the light passing through the second light guide plate is incident, wherein light incident to the second grating is output in a direction perpendicular to one surface of the second grating.
Including,
The light transmitted through the first grid,
According to the diffraction conditions of the first grating is transmitted to the interior of the second light guide plate having the same refractive index as the refractive index of the first light guide plate,
The first light beam expanding unit and the second light beam expanding unit,
One surface of the first lattice constituting the first light beam expanding unit is disposed to be in contact with each other and one surface of the second light guide plate constituting the second light beam expanding unit to have a geometric cross-sectional structure,
A light path control device connected to the first light beam expansion unit and the second light beam expansion unit at a slope according to the first transmission angle so that the light beam transmitted through the first grating enters the interior of the second light guide plate. According to claim 1,
The incident light beam,
A light path control device incident on the injection surface in a P-polarized state in consideration of the surface reflectivity generated at the injection surface of the first light guide plate according to the refractive index of air. delete According to claim 1,
The first transmission angle,
A light path control device determined by a first incident angle of light incident on the first light guide plate, a grating direction of the first grating, and a grating period of the first grating. delete According to claim 1,
The output light beam,
A beam path control device in which the width of a beam is enlarged before and after passing through the first grating by the incident wave field of the light incident from the injection surface. According to claim 1,
The transmitted light,
A light beam path control device in which a width of a light beam is enlarged before and after passing through the second grating by an incident wave field of the light beam transmitted into the second light guide plate. According to claim 1,
The output light beam,
A light path control device generated through a coherent incident wave field and having a spatially homogeneous intensity. According to claim 1,
The second grid,
Considering the angle of incidence of light passing through the second light guide plate, the angle of incidence of the light beam is determined by the second transmission angle and the refractive index of the second light guide plate. Connected light path control device. delete A light condenser for converting light beams output from the light source into parallel straight beams;
The first light beam enlargement unit-the first grating transmitted through the first grating through the first grating in accordance with the incident wave length of the incident light incident on the injection surface of the first light guide plate by the light output from the light converging unit The light transmitted through the light beam is enlarged by the incident wave field, and transmitted through the second light guide plate; And
A second light beam expanding unit outputs through the second light guiding plate in a vertical direction to a display through a second grid according to the incident wave length of the light beam passing through the second light guide plate through the second light grid The transmitted light is output to the display by expanding the width of the light by the incident wave field;
Including,
The light transmitted through the first grid,
According to the diffraction conditions of the first grating is transmitted to the interior of the second light guide plate having the same refractive index as the refractive index of the first light guide plate,
The first light beam expanding unit and the second light beam expanding unit,
One surface of the first lattice constituting the first light beam expander is disposed to be in contact with each other and one surface of the second light guide plate constituting the second light beam expander, and has a geometric cross-sectional structure.
A light path control device connected to the first light beam expansion unit and the second light beam expansion unit at a slope according to a first transmission angle so that the light beam transmitted through the first grating enters the interior of the second light guide plate. The method of claim 11,
The first light beam expanding unit,
A first light guide plate from which the light beam output from the light source is incident-The light beam is incident on the injection surface of the first light guide plate at a first incident angle and transmitted at a first transmission angle, and output in a vertical direction with respect to the first grid being-; And
A first grating through which the light incident on the first light guide plate is transmitted to the interior of the second light guide plate, wherein the light transmitted through the first grating is a second incident angle corresponding to the first transmission angle on the grating surface of the first grating. Is incident and is transmitted into the second light guide plate at the second transmission angle-;
Light beam path control device comprising a. The method of claim 12,
The incident light beam,
A light path control device incident on the injection surface in a P-polarized state in consideration of the surface reflectivity generated at the injection surface of the first light guide plate according to the refractive index of air. delete The method of claim 12,
The first transmission angle,
A light path control device determined by a first incident angle of light incident on the first light guide plate, a grating direction of the first grating, and a grating period of the first grating. delete The method of claim 12,
The second light beam expanding unit,
A second light guide plate through which the light transmitted through the first grating passes through and enters the second grating, wherein the light passing through the second light guide plate is determined according to the second transmission angle and the refractive index of the second light guide plate; And
A second grating through which the light passing through the second light guide plate is incident-A light incident on the second grating is output in a direction perpendicular to one surface of the second grating-
Light beam path control device comprising a. The method of claim 17,
The transmitted light,
A light beam path control device in which a width of a light beam is enlarged before and after passing through the second grating by an incident wave field of the light beam transmitted into the second light guide plate. The method of claim 17,
The output light beam,
A light path control device generated through a coherent incident wave field and having a spatially homogeneous intensity. The method of claim 17,
The second grid,
A light path control device connected to one surface of the second light guide plate so that light is emitted at an angle perpendicular to the light exit surface of the second grating in consideration of the incident angle of the light beam passing through the second light guide plate.

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