KR101857818B1 - Beam Combining Panel Using Patterned Halfwave Retarder And Method For Manufacturing The Same - Google Patents

Abstract

The present invention relates to a light-coupling panel using a patterned half-wave retardation plate for combining light emitted from two adjacent areas and a manufacturing method thereof. The optical coupling panel according to the present invention includes: a substrate corresponding to a display panel having a plurality of pixels arranged in a matrix manner; A first patterned half wave plate disposed on the substrate in a region corresponding to the first pixel; And a second patterned half wave plate disposed on an area of the substrate corresponding to a second pixel located on one side of the first pixel. By combining the optical coupling panel according to the present invention with a spatial light modulation panel of a phase modulation type, it is possible to maximize coupling efficiency of phase-modulated light and provide a high-brightness and accurate stereoscopic image.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a fiber coupled panel (PDP)

The present invention relates to a light-coupling panel using a patterned half-wave retardation plate for combining light emitted from two adjacent areas and a manufacturing method thereof. More particularly, the present invention relates to a patterned half-wave retarder that is a light coupling panel that combines two light beams emitted from two neighboring pixels in a polarized light modulator using phase modulation, and a method of manufacturing the same.

Recently, three dimensional (3D) image and image reproduction techniques have been actively studied. 3D image related media is expected to lead the next generation imaging device as a realistic image media with a new concept that raises the level of visual information one more level. The conventional 2D image system provides the plane image, but the 3D image system is the ultimate image realization technology in terms of showing the actual image information of the object to the observer.

Methods for reproducing three-dimensional stereoscopic images include a stereoscopic method, an auto-stereoscopy method, a volumetric method, a holography method, and an integral imaging method Research and development. Among them, the holography method is a method which can feel the stereoscopic feeling most like the real without observing the special glasses when observing the holography produced by the laser. Therefore, the holography method is excellent in three-dimensional feeling and has a characteristic of feeling a stereoscopic effect even in a single view, and it is known as an ideal method for an observer to feel a stereoscopic image without fatigue.

The holographic method uses the principle of recording and reproducing an interference signal obtained by superimposing light (object wave) reflected from an object and light (reference wave) having coherence. An interference fringe formed by causing an object wave scattered by colliding with an object using a highly coherent laser light to meet with a reference wave incident from another direction is recorded on a photographic film. When an object wave and a reference wave meet, an interference fringe due to interference is formed. The amplitude and phase information of the object are also recorded in this fringe pattern. By irradiating reference light to the interference fringes recorded in this manner, the interference information recorded in the hologram is restored, and the three-dimensional stereoscopic effect is felt. A series of processes for implementing a three-dimensional image using such a recording and restoration principle is called holography.

A computer generated hologram (CGH) has been developed as a method for computer generated holograms for storage, transmission and image processing. This computer-generated hologram has been developed in various ways so far. Recently, a system for displaying a computer-generated hologram of a moving image without developing a computer-generated hologram of a still image has been developed due to the development of the digital industry.

A computer generated hologram is an interference pattern that is stored directly in a hologram using a computer. The interference fringe image is generated by a computer and then transmitted to a spatial light modulator such as a liquid crystal-spatial light modulator (LC-SLM), and the reference light is irradiated to the SLM to restore / Playback. 1 is a block diagram of a digital hologram image reproducing apparatus embodying a computer generated hologram method according to the related art.

Referring to FIG. 1, an interference fringe image corresponding to a stereoscopic image to be implemented in the computer 10 is generated. The generated interference fringes are transmitted to the SLM 20. The SLM 20 may be formed of a transmissive liquid crystal display panel to display an interference pattern. On one side of the SLM 20, a laser light source 30 to be used as a reference light is located. The expander 40 and the lens 50 are sequentially arranged in order to uniformly project the reference light 90 irradiated from the laser light source 30 to the front surface of the SLM 20. [ The reference light 90 emitted from the laser light source 30 is irradiated to one side of the SLM 20 through the expander 40 and the lens 50. [ When the SLM 20 is a transmissive liquid crystal display panel, a three-dimensional stereoscopic image 80 is displayed on the other side of the SLM 20 by the interference pattern of the hologram implemented in the SLM 20. [

The holographic stereoscopic image display apparatus shown in FIG. 1 includes a light source 30 for generating a reference light 90, an expander 40, and a lens 50, all of which occupy a considerable volume. When such a system is constructed, the volume is considerably large and the weight is large, so that it is not suitable for a light-weight small-sized display device, which is a recent trend. Therefore, it is required to realize a holographic stereoscopic image system that realizes the ultimate stereoscopic image in the non-spectacle mode, as a thin film flat plate type.

A holographic stereoscopic image display device which has been implemented as a thin film flat panel type has been proposed. US Pat. No. 5,416,618 discloses a holographic stereoscopic image display device using two liquid crystal display devices. However, US 5,416,618 uses a spatial light modulation panel for phase modulation and a spatial light modulation panel for amplitude modulation. There are difficulties in aligning the two SLMs because of the combination of the two SLMs, the cost is high because two liquid crystal panels are used, the driving is complicated because the two panels are driven, and the thickness is thick.

An object of the present invention is to provide a light coupling panel for modulating a complex amplitude by combining two outgoing lights modulated differently in phase of incident light in a spatial light modulation panel and a method of manufacturing the same. Another object of the present invention is to provide a light coupling panel disposed on a front surface of a spatial light modulation panel using a liquid crystal display panel to form a holographic pattern for a stereoscopic image by interposing light that is phase- .

In order to achieve the object of the present invention, the optical coupling panel according to the present invention comprises: a substrate corresponding to a display panel having a plurality of pixels arranged in a matrix manner; A first patterned half wave plate disposed on the substrate in a region corresponding to the first pixel; And a second patterned half wave plate disposed on an area of the substrate corresponding to a second pixel located on one side of the first pixel.

Wherein the first patterned half wave plate is disposed in an area corresponding to odd-numbered pixel columns among the plurality of pixels; And the second patterned half wave plate is disposed in an area corresponding to an even-numbered pixel column among the plurality of pixels.

And the optical axes of the first patterned half wave plate and the second patterned half wave plate are shifted from each other by 45 degrees.

The optical axis of the first patterned half wave plate is set parallel to the vertical side of the substrate and the optical axis of the second patterned half wave plate is set in a direction inclined at 45 degrees with respect to the horizontal side of the substrate.

And the display panel emits linearly polarized light in a direction parallel to a vertical side of the substrate at the pixels.

The optical axis of the first patterned half wave plate is set to a direction tilted by 67.5 degrees with respect to the horizontal direction of the substrate and the optical axis of the second patterned half wave plate is set in a direction inclined by 22.5 degrees with respect to the horizontal direction of the substrate .

And the display panel emits light linearly polarized in the direction of 45 degrees with respect to a horizontal side of the substrate at the pixels.

According to another aspect of the present invention, there is provided a method of manufacturing a photo-bonding panel, including: coating an alignment film on a transparent substrate; Orienting the entire orientation film in a first direction; Redirecting a portion of the alignment layer exposed in the mask in a second direction that is shifted by 45 degrees from the first direction using a mask having a matrix pattern on the alignment layer; Applying a liquid crystal material on the alignment layer arranged so that the region oriented in the first direction and the region oriented in the second direction are adjacent to each other; And curing the liquid crystal material.

Wherein the liquid crystal material is applied with a thickness of d value satisfying? N x d =? / 2 where? N is the refractive index anisotropy of the liquid crystal material and? Is the wavelength of the green light.

The liquid crystal material includes a reactive mesogen material having reverse dispersion characteristics.

The optical coupling panel according to the present invention is formed on a front surface of a spatial light modulation panel for a holographic stereoscopic image display apparatus, which is formed into a thin film flat plate using a patterned half-wave retarder and is similarly formed as a thin film flat plate. In addition, the optical coupling panel according to the present invention improves the optical coupling ratio in the spatial light modulation panel for generating a holographic stereoscopic image in the space by phase-changing the backlight in each of the two neighboring pixels and complex-combining the backlight. Therefore, by combining the optical coupling panel according to the present invention with the spatial light modulation panel of the phase modulation type, it is possible to maximize the coupling efficiency of the phase-modulated light and provide a high-brightness and accurate stereoscopic image.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a configuration of a digital hologram image reproducing apparatus embodying a computer generated hologram system according to the prior art; Fig.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a stereoscopic image display device, and more particularly to a stereoscopic image display device using a transmissive liquid crystal display device.
3 is a sectional view showing the structure of a spatial light modulation panel according to the present invention and a light coupling panel according to the present invention disposed on the front surface thereof.
FIGS. 4A to 4C are cross-sectional views illustrating a pixel of a spatial light modulator according to the present invention. FIG. 4A to FIG. 4C are diagrams illustrating a variation in the arrangement of liquid crystal molecules according to the magnitude of voltage difference V applied to the liquid crystal layer, ) Figures showing changes.
5 is a cross-sectional view illustrating a holographic stereoscopic image display apparatus having a transmissive liquid crystal display panel according to the present invention.
6 is a schematic view for explaining the structure and operation of the optical coupling panel according to the first embodiment of the present invention;
7 is a schematic view for explaining the structure and operation of the optical coupling panel according to the second embodiment of the present invention;
8A to 8C are cross-sectional views illustrating a method of manufacturing a photo-coupling panel according to the present invention.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings, Figs. 2 to 8A to 8C. Like reference numerals throughout the specification denote substantially identical components. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, a detailed description of known technologies or configurations related to the present invention will be omitted when it is determined that the gist of the present invention may be unnecessarily obscured.

First, referring to FIG. 2, a thin film flat holographic stereoscopic image display apparatus using a transmission type liquid crystal display device as a spatial light modulator according to the present invention will be described. FIG. 2 is a schematic view showing a structure of a stereoscopic image display device using a digital holography method using a transmissive liquid crystal display device according to the present invention.

In the holographic stereoscopic image display apparatus according to the present invention, the SLM 200 is a transmissive liquid crystal display panel. That is, the SLM 200 is formed of a transmissive liquid crystal display panel in which an upper plate SU and a lower plate SD, which are formed of a transparent glass substrate, face each other and are interposed therebetween through a liquid crystal layer LC. The SLM 200 receives interference fringe pattern data from a computer or a video processing device (not shown) and displays interference fringes. Thin film transistors and color filters constituting the liquid crystal display panel may be formed on the upper plate SU and the lower plate SD, respectively.

A backlight unit (BLU) including a light source (300) and an optical fiber (OF) is disposed on the lower surface of the SLM (200). The light source 300 may be comprised of a laser diode including a red laser diode R, a green laser diode G and a blue laser diode B or a light source 300 with red, green and blue collimated LEDs. have. Meanwhile, the light source 300 may be a light source 300 combining R, G, B or other colors distinguishing red, green, and blue, or may be a single light source such as a white laser diode or a white collimated LED 300). Although the light source 300 may be various, the red, green, and blue laser diodes R, G, and B will be described herein for convenience.

The optical fiber OF is used to evenly guide the reference light emitted from the light source 300 to the lower front surface of the SLM 200 substrate. For example, the laser diodes R, G, and B may be disposed on one side of the backlight unit BLU. The laser light emitted from the laser diodes (R, G, B) can be guided to be magnified and emitted from the lower surface of the SLM 200 using the optical fibers OF. The optical fibers OF may be arranged to correspond to the entire surface of the SLM 200 which is a liquid crystal panel. Particularly, a plurality of light outgoing portions OUT for emitting a laser light to the outside of the optical fiber OF by removing a part of the clad surrounding the core of the optical fiber OF are formed so that the laser light is irradiated on the entire surface of the liquid crystal panel . An optical sheet 500 is arranged between the SLM 200 and the optical fiber OF to adjust the parallel reference light to be parallel to the SLM 200 while maintaining the reference light expanded by the optical fiber OF. .

In the present embodiment, the backlight unit (BLU) discloses only a schematic structure using the optical fibers (OF). In the case where the color pixels constituting the SLM 200 are arranged in the same color with respect to one column, the optical fibers OF corresponding to the respective colors may be arranged to correspond to one column. Alternatively, a backlight unit (BLU) in which a surface-emission laser diode corresponding to each pixel is formed at a position corresponding to each color pixel can also be used. Since the core contents of the present invention are not in the backlight unit (BLU), detailed examples are omitted.

The SLM 200 according to the present invention performs phase modulation on the backlight emitted from the backlight unit (BLU), and then phase-modulates the two adjacent lights having different phase values to thereby synthesize the holographic image . Accordingly, it is preferable that the SLM 200 according to the present invention includes a light coupling panel BC which is adjacent to the front surface of the SLM 200 and effectively combines two lights having different phases.

Hereinafter, the spatial light modulator 200 and the optical coupling panel BC, which are core components of the present invention, will be described in detail. 3 is a cross-sectional view showing the structure of a spatial light modulation panel according to the present invention and a light coupling panel according to the present invention disposed on the front surface thereof.

The spatial light modulator 200 according to the present invention is composed of a plurality of pixels (PXLs) having a matrix arrangement for displaying a stereoscopic image. The spatial light modulator according to the present invention includes an upper substrate US and a lower substrate LS opposed to each other and a liquid crystal layer EC interposed therebetween. The upper electrodes UE allocated to the pixels PXL are formed in a matrix array on the inner surface of the upper substrate US and the lower electrodes LE are formed in a matrix array on the inner surface of the lower substrate LS .

The liquid crystal layer EC preferably includes an ECB (Electrically Controlled Birefringence) mode liquid crystal material. In particular, it is preferable that the liquid crystal layer LC in the ECB mode is controlled so that the phase change can be modulated from 0 to 2? With respect to the light passing therethrough. The phase change is determined by the product of the refractive index anisotropy (? N) of the liquid crystal material and the thickness (or cell gap) d of the liquid crystal layer.

And an upper insulating layer UIN covering the upper electrodes UE. In this case, the upper insulating film UIN may be used as an alignment film for setting the initial alignment direction of the liquid crystal layer EC. Similarly, it may further include a lower insulating film LIN covering the lower electrodes LE. In this case also, the lower insulating film LIN may be used as an alignment film for setting the initial alignment direction of the liquid crystal layer EC.

When a voltage difference is generated between the upper electrode UE and the lower electrode LE and an electric field is formed therebetween, the alignment direction of the liquid crystal molecules constituting the liquid crystal layer EC is changed. FIGS. 4A to 4C are cross-sectional views illustrating a pixel of a spatial light modulator according to the present invention. FIG. 4A to FIG. 4C are diagrams illustrating a variation in the arrangement of liquid crystal molecules according to the magnitude of voltage difference V applied to the liquid crystal layer, ).

The liquid crystal of the ECB mode is a liquid crystal material which generates refractive index anisotropy by controlling the tilted angle of liquid crystal molecules by the applied voltage difference. Namely, the refractive index anisotropy? N is expressed by the following equation (1).

Here, θ is the angle binary liquid crystal molecules are inclined with respect to the horizontal direction, n _o is the refractive index of the speed of the liquid crystal molecule orientation, n _e is the refractive index in the major axis direction of liquid crystal molecules, and n _eff is the inclined angle of the liquid crystal molecules ≪ / RTI >

4A shows a state in which no electric field is formed between the upper electrode UE and the lower electrode LE. If no electric field is applied to the liquid crystal layer EC (V = 0), the liquid crystal molecules maintain their initial alignment state. In the initial arrangement, since θ = 0, n _eff is equal to n _o . That is, the difference in refractive index is expressed by? N = n _o - n _o = 0. That is, since there is no refractive index difference, there is no change in the phase of light passing through the liquid crystal molecules (Δφ = 0).

4B shows a case where a certain voltage between the minimum voltage (V = 0) and the maximum voltage (V _max ) is applied between the upper electrode UE and the lower electrode LE. When a voltage V _a between 0 and V _max is applied to the liquid crystal layer EC (V = Va), the liquid crystal molecules are tilted to the tilt angle? _A (? =? _A ). Accordingly,? N increases or decreases, and the phase of the light passing through the liquid crystal molecules changes according to the product of the value of? N and the thickness d of the liquid crystal layer (?? =? _A ).

4C shows a case where the maximum voltage V _max is applied between the upper electrode UE and the lower electrode LE. When a maximum electric field is applied to the liquid crystal layer EC, the liquid crystal molecules have a completely aligned state along the electric field direction. That is,? = 90 degrees. Then, light traveling through the panel passes through the long axis of the liquid crystal. Thus, n _eff is equal to n _e . Therefore, Δn is n _e - n _o = Maximum refractive index difference value. In the present invention, the d value is set in accordance with the maximum Δn (n _e -n _o ) of the liquid crystal material so that the maximum value of the phase change value KΔn × d is 2π. Therefore, the change of the phase (?) Of the light passing through the liquid crystal molecules becomes 2? (?? = 2?).

A spatial light modulator that produces diffracted light corresponding to a holographic stereoscopic image using a transmissive liquid crystal display panel having a liquid crystal cell designed to change the phase of input light from 0 to 2? Will be described in detail. 5 is a cross-sectional view illustrating a holographic stereoscopic image display apparatus having a transmissive liquid crystal display panel according to the present invention. FIG. 5 is a partial enlarged view of two neighboring pixels, and shows the structure and operation principle of the spatial light modulation panel according to the present invention.

The spatial light modulation panel according to the present invention includes pixels arranged in a matrix manner, such as a liquid crystal display panel. Modulates the phase of light passing through two pixels with a pair of neighboring pixels as basic units, and combines the two adjacent lights modulated in different phases to induce a complex amplitude modulation.

Referring to FIG. 5, the holographic stereoscopic image display apparatus according to the present invention includes a flat backlight unit (BLU) and a spatial light modulation panel 200 according to the present invention. After passing through the spatial light modulation panel 200, the backlight BL emitted from the backlight unit BLU is phase-modulated and recombined to reproduce the stereoscopic image in a holographic manner.

Here, it is preferable that the backlight BL is incident in parallel to the spatial light modulation panel 200 in a linearly polarized state. This is to form a holographic image due to interference by combining the two lights modulated in phase through the spatial light modulation panel 200. Therefore, the spatial light modulation panel 200 according to the present invention is preferably applied to a liquid crystal display device. In particular, it is preferable that the liquid crystal molecules of the liquid crystal layer EC are arranged in the same direction as the linear polarization direction of the incident backlight BL. This is to keep the transmittance of the backlight BL which transmits the liquid crystal layer EC constant.

More specifically, the backlight BL emitted from the backlight unit BLU has amplitude A and phase? 0 as linearly polarized light. The backlight BL passes through a pair of adjacent pixels. At this time, a voltage of V1 is applied to the left pixel (L) to modulate the light passing through the liquid crystal layer (EC) to have a phase of? 1. At the same time, a voltage of V2 is applied to the right pixel R to modulate the light passing through the liquid crystal layer EC to have a phase of? 2. That is, the backlight BL passing through the left pixel L becomes the first modulated light ML1 having the amplitude A and the phase? 1. The backlight BL passing through the right pixel R becomes the second modulated light ML2 having the amplitude A and the phase? 2. Since the first modulated light ML1 and the second modulated light ML2 are adjacent to each other, interference occurs and optical coupling occurs therebetween to generate combined light CL.

At this time, the wave equation of the coupling light CL satisfies the following equation (2).

Where A is the amplitude,? ₁ is the phase of the first modulated light, and? ₂ is the phase of the second modulated light.

According to Equation (2), the combined light CL has an amplitude component of 2A cos [( ₁ - ₂ ) / 2] and a phase component of e ^{i (1 + 2) / 2} . That is, both the amplitude and the phase can be modulated by modulating only the phase with respect to the input light and combining the two modulated lights to perform complex amplitude modulation. As described above, it is possible to form a holographic image in space by adjusting the amplitude and the phase by complex coupling light of two adjacent pixels modulated in different phases in space.

As described above, the spatial light modulation panel 200 according to the present invention modulates the phases of light passing through two neighboring pixels differently, and combines them to reproduce a holographic image through complex modulation. Here, the spatial light modulation panel 200 according to the present invention further includes a light coupling panel BC on the front surface of the spatial light modulation panel 200 to facilitate complex coupling of two light modulated by the two adjacent pixels in space.

Hereinafter, preferred embodiments of the optical coupling panel BC, which is a key content of the present invention, will be described in detail with reference to FIGS. 6 to 8A to 8C. FIG. 6 is a schematic view illustrating the structure and operation of the optical coupling panel according to the first embodiment of the present invention.

Referring to FIG. 6, the optical coupling panel BC according to the first embodiment is positioned on the front surface of the spatial light modulation panel 200 according to the present invention described above. A backlight unit (BLU) is disposed on the back surface of the spatial light modulation panel (200). The optical coupling panel BC according to the first exemplary embodiment is a patterned half-wave plate (BWM) corresponding to column unit cells in the vertical direction among a plurality of pixels having a matrix arrangement constituting the spatial light modulation panel 200 And patterned half wave retarders. For example, the first patterned half wave plate PHW1 is disposed on the front side of the pixels in the odd row, and the second pattern half wave plate PHW2 is disposed on the front side of the pixels in the even row row.

The backlight unit (BLU) provides a backlight (BL) having no special polarization property to the spatial light modulation panel (200), even if the light source is laser light. As described above, the spatial light modulation panel 200 applies a liquid crystal display panel, and linearly polarizes the backlight (BL) to modulate the phase. Therefore, the light emitted from the spatial light modulation panel 200 is light that is linearly polarized in one direction, even though it has a different phase from the neighboring light. For example, linearly polarized light in a direction perpendicular to the vertical sides of the spatial light modulation panel 200. [

As described above, in order to effectively combine two light beams emitted from two neighboring pixels in the horizontal direction (horizontal direction) of linearly polarized light in the vertical direction to cause interference, in order to increase the efficiency, It is preferable that the directions of polarization of the two lights to be perpendicular to each other. For example, it is preferable that the vertical linearly polarized light emitted from the first pixel column maintains the original vertical linearly polarized state, and the vertical linearly polarized light emitted from the second pixel line changes into the horizontal linearly polarized light state.

To this end, the first patterned half-wave plate PHW1 is set in front of the odd-numbered pixel rows and the light-transmitting axis is set in parallel with the direction of the vertical line-polarized light. In front of the even- It is preferable to arrange the second patterned half wave plate PHW2 inclined. 6, the first patterned half wave plate PHW1 and the second patterned half wave plate PHW2 are arranged in the order of the optical coupling panel BC). As shown in Fig. 6, the light of the pixel transmitted through the first patterned half wave plate PHW1 maintains the original vertical linearly polarized state. On the other hand, the light of the pixel transmitted through the second patterned half wave plate PHW2 changes into a horizontal linearly polarized light state. Therefore, the two phase modulated lights emitted from two neighboring pixels in the horizontal direction are orthogonal to each other in the linearly polarized light state, thereby maximizing the interference efficiency. That is, the holographic stereoscopic image display device having the optical coupling panel BC according to the present invention can provide a stereoscopic image with a further improved brightness.

The optical coupling panel BC according to the first embodiment is formed by patterning a half wave plate in units of pixel columns. The direction of the linearly polarized light is changed so that the phases of two lights emitted from two neighboring pixel columns in a pixel column unit are orthogonal to each other. For this purpose, the phase of the light emitted from one pixel column is maintained, and the direction of the linearly polarized light is changed by delaying the phase of the light emitted from the adjacent pixel row by? / 2 phase without changing the direction of the linearly polarized light. In other words, when making and arranging a patterned half wave plate to make the phases of two neighboring lights orthogonal to each other, the wavelength of light passing through the half wave plate should be designed in consideration of λ.

In the holographic stereoscopic image display apparatus according to the first embodiment, light is linearly polarized in the spatial light modulation panel 200 in the vertical direction, and is linearly polarized in the vertical and horizontal directions in the optical coupling panel BC The adjustment is taken into account when using a monochromatic light source. Particularly, in a case where a green light source having a wavelength of 532 nm is used, it is designed so as to have the maximum luminance in the front direction.

In a holographic stereoscopic image display device implementing a natural color, since a three-primary-color light source including Red (Red), Green (Green), and Blue (Blue) is used, it is necessary to design the stereoscopic image display device so as to have the maximum luminance also in this case. In particular, since three sub-pixels of RGB three primary colors are gathered to form one pixel, a patterned half-wave plate commonly assigned to three sub-pixels in RGB must be designed. Hereinafter, with reference to FIG. 7, a description will be given of a light coupling panel having an optimum optical coupling efficiency in the case of using a three-color light source. 7 is a schematic view for explaining the structure and operation of the optical coupling panel according to the second embodiment of the present invention.

The spatial light modulation panel 200 according to the second embodiment of the present invention is designed to emit linearly polarized light in a direction inclined by 45 degrees with respect to the vertical side of the spatial light modulation panel 200. Among the lights polarized in the direction of 45 degrees, the light emitted from the odd-numbered pixel columns changes the linear polarization state in the vertical direction, and the light emitted from the even-numbered pixel columns changes the linear polarization state in the horizontal direction.

To this end, a third patterned half-wave plate PHW3 is arranged in front of the odd-numbered pixel columns in the direction in which the light transmission axis is inclined 67.5 degrees with respect to the horizontal direction of the optical coupling panel BC, It is preferable to dispose the fourth patterned half wave plate PHW4 whose axis is inclined by 22.5 degrees with respect to the horizontal direction of the optical coupling panel BC. 8, the third patterned half-wave plate PHW3 and the fourth patterned half-wave plate PHW4 are arranged in such a manner as to correspond to the respective pixel columns of the spatial light modulation panel 200, BC).

As shown in FIG. 7, the light of the pixel row transmitted through the third patterned half wave plate PHW3 changes from the linearly polarized light state to the vertical linearly polarized light state in the original 45 degree direction. On the other hand, the light of the pixel row transmitted through the fourth patterned half wave plate PHW4 changes into a horizontal linearly polarized light state. Therefore, the two phase modulated lights emitted from two neighboring pixels in the horizontal direction are orthogonal to each other in the linearly polarized light state, thereby maximizing the interference efficiency. In other words, the holographic stereoscopic image display device having the optical coupling panel BC according to the second embodiment can further improve brightness and provide accurate stereoscopic images.

Hereinafter, a method of manufacturing the optical coupling panel according to the present invention will be described in detail with reference to FIGS. 8A to 8C. 8A to 8C are cross-sectional views illustrating a method of manufacturing the optical coupling panel according to the present invention.

As shown in Fig. 8A, an alignment film (ALG) is applied on the transparent substrate SUB. The entire alignment film (ALG) is oriented in the first direction by using the front exposure method in which the alignment film (ALG) is irradiated with ultraviolet rays linearly polarized in the first direction. The horizontal arrows shown in Fig. 8A mean the alignment pattern in the first direction formed in the alignment film ALG. In the case of the optical coupling panel BC according to the first embodiment, the first direction is preferably set to the horizontal direction or the vertical direction, and in the case of the optical coupling panel BC according to the second embodiment, It is preferable to set the direction to 67.5 degrees with respect to the horizontal direction.

A part of the alignment film ALG is partially removed by using a partial exposure method in which the mask MA is covered on the alignment film ALG aligned in the first direction and the ultraviolet ray linearly polarized in the second direction is irradiated, The orientation direction is changed in two directions. The vertical arrows shown in Fig. 8B indicate the alignment pattern in the second direction formed on the alignment film (ALG). In the case of the optical coupling panel BC according to the first embodiment, it is preferable that the second direction is set at 45 degrees with respect to the horizontal direction, and in the case of the optical coupling panel BC according to the second embodiment, It is preferable to set the direction to 22.5 degrees with respect to the horizontal direction.

At this time, it is preferable that the pattern of the mask MA corresponds to the pattern of the pixel column constituting the spatial light modulation panel 200. For example, it is preferable to design the mask MA such that the alignment pattern in the first direction is assigned to the odd-numbered pixel columns and the alignment pattern in the second direction is assigned to the even-numbered pixel columns. It is important to set a difference of 45 degrees between the alignment pattern in the first direction and the alignment pattern in the second direction. As a result, the first patterned half wave plate PHW1 and the second patterned half wave plate PHW2, or the third patterned half wave plate PHW3 and the fourth patterned half wave plate PHW4, 45 degrees.

After the orientation pattern in the first direction is formed over the entire alignment film (ALG) by the front exposure method as described above, a part of the alignment film (ALG) in which the alignment pattern in the first direction is formed by the partial exposure method is used as the alignment pattern in the second direction Is used. For this purpose, it is preferable to use a higher energy than the front exposure in the partial exposure.

As shown in FIG. 8C, the reactive mesogen liquid crystal layer RM is entirely coated on the alignment layer (ALG) having the alignment pattern in the first direction and the alignment pattern in the second direction. The reactive mesogen liquid crystal layer RM is irradiated with ultraviolet rays to cure the reactive mesogen liquid crystal layer RM. Then, the reactive mesogen liquid crystal layer RM has a pattern in the same direction as the alignment pattern of the alignment film (ALG) and is cured. For example, a first patterned half wave plate PHW1 or a third patterned half wave plate PHW3 is formed at a position corresponding to an odd pixel column, and a second patterned half wave plate PHW2 is formed at a position corresponding to an even- Or the fourth patterned half wave plate PHW4 is formed.

Although not shown in the figure, after the reactive mesogen liquid crystal layer RM is cured, an antireflection coating layer is further formed on the back surface of the substrate SUB and a protective film is further attached to complete the final optical coupling panel.

Here, the thickness of the reactive mesogen liquid crystal layer RM is represented by? N x d =? / 2 (where? N is the refractive index anisotropy difference of the reactive mesogen liquid crystal material and? Is the wavelength of the polarizing source) It is preferable to have a d value satisfying the condition of In the first embodiment, when green monochromatic light is used,? Is set to 532 nm. Also in the second embodiment using the three primary colors, it is preferable to set? To 532 nm, which is the green light, as a reference. However, in order to obtain the maximum transmittance in the first embodiment, the green monochromatic light is linearly polarized in the vertical direction, the first direction is set to the horizontal direction or the vertical direction, and the second direction is set to the 45 degree direction with respect to the horizontal direction . In addition, in the second embodiment, in order to make all of the three-color light sources have the maximum transmittance, the tricolor light is linearly polarized in a direction inclined at 45 degrees with respect to the horizontal direction, the first direction has a direction of 67.5 degrees with respect to the horizontal direction, It is preferable to set the two directions to have a direction of 22.5 degrees with respect to the horizontal direction.

In the case of Example 2 where? Is set to 532 nm which is the green light, the light of red and blue wavelengths may not be output properly in the direction of +/- 45 degrees. As a result, when observing from the front, there may occur a problem that the color shift phenomenon and / or the front luminance is lowered in the white light. This is because there is a difference in chromatic dispersion characteristics for each wavelength of RGB.

In order to solve this problem, it is preferable to use a reactive mesogen having a reverse dispersion property in selecting the material of the reactive mesogen. The reactive mesogen having a reverse dispersion property has an effect of reducing chromatic dispersion than a reactive mesogen material having a positive dispersion property, thereby reducing color shift and luminance reduction problems due to chromatic dispersion in the front direction. The following Table 1 shows the results of the measurement of the transmittance of the reactive meso having the inverse dispersion property with respect to the front luminance value of the optical coupling panel including the reactive mesogen having the positive dispersion property when the white light having the wavelength of 125 nm and the white light having the wavelength of 137 nm were used as the backlight. 0.0 > brightness < / RTI >

Reactive mesogenic material Application of quasi-dispersion material Application of reverse dispersion material Green wavelength / 4 125 nm 137 nm 125 nm 137 nm Luminance value 150.0 (Ref.) 153.0 152.6 156.5

As can be seen from the above Table 1, when a light-coupling panel including a reactive mesogen material having a positive dispersion property is used to transmit light of 125 nm, a front luminance value of 150.0 is set as a reference value. As shown in Table 1, when the optical coupling panel including the reactive mesogen material having the reverse dispersion property is used, the front luminance value is improved by 1.7% with respect to the reference value in the case of 125 nm light, And 4.3%, respectively.

In selecting the material of the reactive mesogen, only the reactive mesogens having the positive dispersion property or the reverse dispersion property can be selected and used, but the reactive mesogens having the positive dispersion property and the reactive mesogens having the reverse dispersion property May be mixed and used. Most preferably, the content of the reactive mesogen material having the reverse dispersion property accounts for at least 25% or more in the entire reactive mesogen liquid crystal layer (RM).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

10: computer 20, 200: SLM (spatial light modulator)
30, 300: laser light source 40: expander
50: Lens 80: Output image
90: reference light 500: optical sheet
SU: top plate SD: bottom plate
LC: liquid crystal layer R: red laser diode
G: green laser diode B: blue laser diode
OF: Fiber optic BLU: Backlight unit
OUT: light output portion IN: light input portion
500: Optical film
US: upper substrate LS: lower substrate
UE: upper electrode LE: lower electrode
UIN: upper insulating film EIN: lower insulating film
EC: ECB mode liquid crystal layer BL: backlight
L: left pixel R: right pixel
ML1: first modulated light ML2: second modulated light
CL: Coupling light BC: Optical coupling panel
SUB: transparent substrate ALG: alignment film
RM: reactive mesogen liquid crystal layer MA: mask
PHW1: 1st patterned half wave plate PHW2: 2nd patterned half wave plate
PHW3: Third patterned half wave plate PHW4: Fourth patterned half wave plate

Claims (10)

A substrate corresponding to a display panel having a plurality of pixels arranged in a matrix manner;
A first patterned half wave plate disposed on an area of the substrate corresponding to the first pixel and configured to linearly polarize light emitted from the first pixel in a first direction;
A second patterned half wave plate disposed on an area of the substrate corresponding to a second pixel located at one side of the first pixel and linearly polarized in a second direction perpendicular to the first direction, ; And
And a cured liquid crystal material disposed on the first patterned half wave plate and the second patterned half wave plate, the curable liquid crystal material including at least 25% of a reactive mesogen material having a reverse dispersion property. .
The method according to claim 1,
Wherein the first patterned half wave plate is disposed in an area corresponding to odd-numbered pixel columns among the plurality of pixels;
And the second patterned half wave plate is disposed in an area corresponding to an even-numbered pixel column among the plurality of pixels.
The method according to claim 1,
And the optical axes of the first patterned half wave plate and the second patterned half wave plate are shifted from each other by 45 degrees.
The method of claim 3,
Wherein the first patterned half wave plate has an optical axis set parallel to a vertical side of the substrate,
Wherein the second patterned half wave plate has an optical axis set in a direction inclined by 45 degrees with respect to a horizontal side of the substrate.
5. The method of claim 4,
Wherein the display panel emits linearly polarized light in a direction parallel to a vertical side of the substrate at the pixels.
The method of claim 3,
The optical axis of the first patterned half wave plate is set in a direction inclined by 67.5 degrees with respect to the horizontal side of the substrate,
Wherein the second patterned half wave plate has an optical axis set in a direction inclined by 22.5 degrees with respect to a horizontal side of the substrate.
The method according to claim 6,
Wherein the display panel emits light linearly polarized in the direction of 45 degrees with respect to a horizontal side of the substrate at the pixels.
Applying an alignment film on the transparent substrate;
Orienting the entire orientation film in a first direction;
Redirecting a portion of the alignment layer exposed in the mask in a second direction that is shifted by 45 degrees from the first direction using a mask having a matrix pattern on the alignment layer;
Applying a liquid crystal material containing at least 25% of a reactive mesogen material having antispersion characteristics on the alignment layer arranged so that the region oriented in the first direction and the region oriented in the second direction are adjacent to each other step; And
And curing the liquid crystal material,
The light passing through the portion oriented in the first direction has a first linearly polarized light direction and the light passing through the portion reoriented in the second direction has a second linearly polarized light direction perpendicular to the first linearly polarized light direction To form the optical coupling panel.
9. The method of claim 8,
Wherein the liquid crystal material is applied with a thickness d having a value satisfying? N x d =? / 2 where? N is the refractive index anisotropy of the liquid crystal material and? Is the wavelength of the green light.
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