KR20130054110A - Beam combining panel using patterned halfwave retarder and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A light bonding panel and a manufacturing method thereof are provided to modulate complex amplitude by bonding two outgoing lights which differently modulated the phase of an incident light in a spatial light modulation panel and forming a holography pattern for the stereo-scopic image by interfering the light differently phase-modulated in the adjacent two pixels by being arranged in a front surface of the spatial light modulation panel using an LCD panel. CONSTITUTION: A light bonding panel(BC) comprises a substrate corresponding to a display panel equipped with a plurality of pixels arranged in a matrix mode; a first patterned half-wave plate(PHW1) and the light boding panel arranged in an area corresponding to a first pixel on the substrate; and a second pattered half-wave plate(PHW2) arranged in the area corresponding to a second pixel positioned at one side of the first pixel on the substrate.

Description

Beam Combining Panel Using Patterned Halfwave Retarder And Method For Manufacturing The Same}

The present invention relates to a light coupling panel using a patterned half-wave retardation plate combining light emitted from two adjacent regions and a method of manufacturing the same. In particular, the present invention relates to a patterned half-wave retardation plate and a method for manufacturing the same, which are light-combining panels combining two lights emitted from two adjacent pixels in a polographic optical modulator using phase modulation.

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.

As a method for reproducing 3D stereoscopic images, methods such as stereoscopy, auto-stereoscopy, volumetric, holography, and integrated imaging are widely used. Research and development. Among these, the holography method is a method that can sense a three-dimensional feeling most similar to the real thing without attaching special glasses when observing the holography produced using a laser. Accordingly, the holography method is excellent in three-dimensionality and is characterized by being able to feel a three-dimensional effect even with a monocular, and is known as the most ideal way for an observer to feel a three-dimensional 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 colliding an object wave scattered by an object with a reference wave incident in another direction using a highly coherent laser light 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 the reference light to the recorded interference fringes, the interference information recorded on the hologram is restored to give a three-dimensional impression. A series of processes for creating three-dimensional images using these recording and reconstruction principles 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 device of FIG. 1 is composed of components occupying a considerable volume, such as a light source 30 for generating a reference light 90, an expander 40, and a lens 50. In the case of constructing such a system, since the volume is quite large and the weight is large, it is not suitable for the light and thin display device of the recent trend. Therefore, it is required to implement a holographic stereoscopic imaging system that realizes an ultimate stereoscopic image in an autostereoscopic manner in a thin film flat panel type.

In the past, a holographic stereoscopic image display device implemented in a thin film flat panel type has been proposed. US Pat. No. 5,416,618 discloses a holographic stereoscopic image display using two liquid crystal displays. However, US Pat. No. 5,416,618 uses a spatial light modulation panel for phase modulation and a spatial light modulation panel for amplitude modulation. The combination of the two SLMs makes it difficult to align the two SLMs, the cost is expensive because the two liquid crystal panels are used, and the driving is complicated and the thickness is thick because the two panels are driven.

An object of the present invention is to provide a light combining panel for modulating a complex amplitude by combining two outgoing light modulated phases of incident light differently in a spatial light modulation panel and a method of manufacturing the same. Another object of the present invention is to provide an optical coupling panel which is disposed on the front surface of a spatial light modulation panel using a liquid crystal display panel and forms a holographic pattern for a stereoscopic image by interfering differently phase-modulated light from two adjacent pixels with each other, and a manufacturing method thereof. To provide.

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

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

The optical axes of the first patterned half-wave plate and the second patterned half-wave plate are offset by 45 degrees from each other.

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

The display panel may emit linearly polarized light from the pixels in a direction parallel to a vertical side of the substrate.

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

The display panel may emit light linearly polarized from the pixels in a 45 degree direction with respect to a horizontal side of the substrate.

In addition, the method of manufacturing a light coupling panel according to the present invention comprises the steps of applying an alignment film on a transparent substrate; Orienting the entire alignment layer in a first direction; Reorienting a portion of the alignment layer exposed to the mask in a second direction that is shifted by 45 degrees with the first direction by using a mask having a matrix pattern on the alignment layer; Applying a liquid crystal material on the alignment layer disposed such 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.

The liquid crystal material is coated with a thickness of d value satisfying Δn × d = λ / 2 (where Δn is the refractive index anisotropy of the liquid crystal material and λ is the wavelength of the green light).

The liquid crystal material is characterized in that it comprises a reactive mesogen (reactive mesogen) material having a reverse dispersion characteristic.

The light coupling panel according to the present invention is formed into a thin film flat panel using a patterned half-wave retardation plate, and is mounted on the front surface of a spatial light modulation panel for a holographic stereoscopic image display device similarly manufactured into a thin film flat panel. In addition, the optical coupling panel according to the present invention improves the optical coupling ratio in the spatial light modulation panel that generates a holographic stereoscopic image in space by complexly combining the backlight after phase shifting in two neighboring pixels, respectively. Accordingly, by combining the light coupling panel according to the present invention with the spatial light modulation panel of the phase modulation method, it is possible to maximize the coupling efficiency of the phase-modulated light, thereby providing a high luminance 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.
Figure 2 is a schematic diagram showing the structure of a digital holography stereoscopic image display device using a transmissive liquid crystal display device according to the present invention.
3 is a cross-sectional view showing a structure of a spatial light modulation panel according to the present invention and a light coupling panel according to the present invention disposed on its front surface.
4A to 4C are cross-sectional views illustrating one pixel of the spatial light modulator according to the present invention, in which the arrangement of liquid crystal molecules and the phase of light passing through the liquid crystal molecules according to the magnitude (V) of the voltage difference applied to the liquid crystal layer. Figures showing change.
5 is a cross-sectional view of a holographic stereoscopic image display device having a transmissive liquid crystal display panel according to the present invention.
6 is a schematic view illustrating the structure and operation of a light coupling panel according to a first embodiment of the present invention.
7 is a schematic view illustrating the structure and operation of a light coupling panel according to a second embodiment of the present invention.
8A to 8C are cross-sectional views illustrating a method of manufacturing the light coupling panel according to the present invention.

Hereinafter, with reference to the accompanying drawings, Figures 2 to 8a-8c, a preferred embodiment of the present invention will be described. 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 panel holographic stereoscopic image display device using a transmissive liquid crystal display device as a spatial light modulator will be described. 2 is a schematic diagram showing the structure of a digital holography stereoscopic image display device using a transmissive liquid crystal display device according to the present invention.

The holographic stereoscopic image display device according to the present invention comprises the SLM 200 as a transmissive liquid crystal display panel. That is, the SLM 200 is formed of a transmissive liquid crystal display panel in which the upper plate SU formed of a transparent glass substrate and the lower plate SD face each other, and are coupled through the liquid crystal layer LC therebetween. The SLM 200 receives interference fringe pattern data from a computer or a video processing device (not shown), and displays the interference fringe. Each of the upper plate SU and the lower plate SD may include a thin film transistor and a color filter constituting the liquid crystal display panel.

The backlight unit BLU including the light source 300 and the optical fiber OF is disposed on the lower surface of the SLM 200. The light source 300 may be configured as a light source 300 using laser diodes including red laser diodes (R), green laser diodes (G), and blue laser diodes (B) or red, green, and blue collimated LEDs. have. Meanwhile, the light source 300 may be a light source 300 that combines R, G, B, or other colors that distinguish red, green, and blue, and may be a single light source such as a white laser diode or a white collimated LED. 300). As described above, the light source 300 may be various. For convenience, the light sources 300 will be described in the case of the red, green, and blue laser diodes R, G, and B.

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, laser diodes R, G, and B may be disposed on one side of the backlight unit BLU. In addition, the laser light emitted from the laser diodes R, G, and B may be extended from the lower surface of the SLM 200 by using the optical fiber OF. The optical fiber OF may be disposed to correspond to the entire surface of the SLM 200 which is a liquid crystal panel. In particular, a plurality of light output parts OUT are formed to remove a part of the clad surrounding the core of the optical fiber OF to emit laser light to the outside of the optical fiber OF so that the laser light is irradiated to the entire liquid crystal panel. Can be. In addition, between the SLM 200 and the optical fiber OF, an optical sheet 500 for adjusting the reference light extended by the optical fiber OF to maintain the size corresponding to the area of the SLM 200 and to run in parallel straight. It may further include.

In the present embodiment, the backlight unit BLU discloses only a schematic structure using the optical fiber OF. When the color pixels constituting the SLM 200 are arranged with the same color pixels based on one column, the optical fibers OF corresponding to each color may be arranged to correspond to one column. Alternatively, a backlight unit BLU in which a surface-emitting laser diode corresponding to each pixel is formed at a position corresponding to each color pixel can also be used. Since the essential contents of the present invention are not in the backlight unit BLU, detailed examples will be omitted.

The SLM 200 according to the present invention phase modulates a backlight emitted from a backlight unit BLU, and then complexly combines two neighboring lights having different phase values to adjust a phase and an amplitude to produce a holographic image. Implement Therefore, it is preferable that the front surface of the SLM 200 according to the present invention includes a light coupling panel BC that effectively combines two lights having neighboring and different phases.

Hereinafter, the spatial light modulator 200 and the light 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 its front surface.

The spatial light modulator 200 according to the present invention is composed of a plurality of pixels PXL 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 facing each other and a liquid crystal layer EC interposed therebetween. On the inner surface of the upper substrate US, the upper electrodes UE assigned to each pixel PXL are formed in a matrix array, and on the inner surface of the lower substrate LS, the lower electrodes LE are formed in a matrix array. .

In addition, the liquid crystal layer EC preferably includes a liquid crystal material in an electrically controlled birefingence (ECB) mode. In particular, the liquid crystal layer LC of the ECB mode is preferably controlled to modulate the phase change from 0 to 2π with respect to the light passing therethrough. The phase change is determined by the product of the refractive index anisotropy (Δn) of the liquid crystal material and the thickness (or cell gap) d of the liquid crystal layer.

The display device may further include 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, the semiconductor device may further include a lower insulating layer LIN covering the lower electrodes LE. Also in this case, the lower insulating film LIN can 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. 4A to 4C are cross-sectional views illustrating one pixel of the spatial light modulator according to the present invention, in which the arrangement of liquid crystal molecules and the phase of light passing through the liquid crystal molecules according to the magnitude (V) of the voltage difference applied to the liquid crystal layer. ) Is a diagram showing a change.

The liquid crystal of the ECB mode is a liquid crystal material that generates refractive anisotropy by controlling the inclination angle of liquid crystal molecules by an applied voltage difference. That is, Δn which is refractive anisotropy is represented by the following equation.

Where θ is the angle at which the liquid crystal molecules are inclined with respect to the horizontal direction, n _o is the refractive index in the minor axis direction of the liquid crystal molecules, n _e is the refractive index in the major axis direction of the liquid crystal molecules, and n _eff is the inclination angle of the liquid crystal molecules. Means the refractive index.

4A illustrates 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 the initial arrangement. N _eff is equal to n _{o in the} initial arrangement state since θ = 0. That is, the difference in refractive index is Δn = n _o -n _o = 0. That is, since there is no difference in refractive index, there is no change in the phase of light passing through the liquid crystal molecules (Δφ = 0).

In Figure 4b shows a case that any voltage between the upper electrode (UE) and lower electrode (LE) the minimum voltage (V = 0) and the maximum voltage (V _max) between jammed. 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 inclined at an inclination angle θ _a (θ = θ _a ). Therefore, Δn increases or decreases, and the phase of light passing through the liquid crystal molecules changes according to the product of the value of Δn and the thickness d of the liquid crystal layer (Δφ = φ _a ).

4C illustrates 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 are completely aligned along the electric field direction. That is, θ = 90 degrees. Then, the light traveling through the panel passes through the long axis of the liquid crystal. Therefore, n _eff is equal to n _e . Therefore, Δn is n _e -n _o = Has the maximum value as the maximum refractive index difference value. In the present invention, the d value is set according to 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 phase (phi) change of the light passing through the liquid crystal molecules is 2π (Δφ = 2π).

As described above, a spatial light modulator for producing 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 the input light from 0 to 2π will be described in detail. 5 is a cross-sectional view of a holographic stereoscopic image display device having a transmissive liquid crystal display panel according to the present invention. 5 includes an enlarged partial view of two neighboring pixels, and shows a structure and an 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, like a liquid crystal display panel. Based on a pair of neighboring pixels as a basic unit, a phase of light passing through the two pixels is differently modulated, and a complex amplitude modulation is induced by combining two adjacent lights having differently modulated phases.

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

Here, the backlight BL may enter the spatial light modulating panel 200 in a linearly polarized state and enter the parallel light. This is to accurately form a holographic image due to interference by combining two phase-modulated lights passing 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 be arranged in the same direction as the linear polarization direction of the incident backlight BL. This is to maintain a constant transmittance of the backlight BL passing through the liquid crystal layer EC.

In more detail, the backlight BL emitted from the backlight unit BLU has an amplitude A and a phase φ 0 as linearly polarized light. The backlight BL passes through a pair of adjacent pixels. At this time, the left pixel L is applied with a voltage of V1 to modulate the light passing through the liquid crystal layer EC to have a phase of? 1. At the same time, the right pixel R is applied with a voltage of V2 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 φ1. In addition, the backlight BL passing through the right pixel R becomes the second modulated light ML2 having an amplitude A and a phase φ2. Since the first modulated light ML1 and the second modulated light ML2 are adjacent to each other, interference occurs and light coupling is generated therebetween to generate the combined light CL.

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

Here, A is amplitude, phi ₁ is phase of first modulated light, and phi ₂ is phase of second modulated light.

According to equation (2), the combined light CL has an amplitude component of ₂ Acos [(φ ₁ -φ ₂ ) / 2] and a phase component of e ^{i (} φ ₁ ⁺ φ ^{2) / 2} . That is, by modulating only the phase with respect to the input light and performing complex amplitude modulation by combining the two phase-modulated lights, both amplitude and phase can be modulated. As described above, the holographic image may be formed in the space by complex-combining light of two adjacent pixels having differently modulated phases in space to adjust amplitude and phase.

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

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

Referring to FIG. 6, the light coupling panel BC according to the first embodiment is located in front of the spatial light modulation panel 200 according to the present invention. In addition, a backlight unit BLU is disposed on the rear surface of the spatial light modulation panel 200. The optical coupling panel BC according to the first exemplary embodiment has a patterned half-wavelength corresponding to column columns in a vertical direction among a plurality of pixels having a matrix array constituting the spatial light modulation panel 200. Patterned Half Wave Retarders. For example, the first patterned half-wave plate PHW1 is disposed in front of the pixels in the odd-numbered column, and the second patterned half-wave plate PHW2 is disposed in front of the pixels in the even-numbered column.

The backlight unit BLU provides the spatial light modulation panel 200 with the backlight BL having no special polarization even if the light source is laser light. As described above, the spatial light modulation panel 200 is a liquid crystal display panel and modulates phase by linearly polarizing the backlight BL. Accordingly, the light emitted from the spatial light modulation panel 200 is light linearly polarized in one direction even though the light emitted from the spatial light modulation panel 200 has a phase different from that of the neighboring light. For example, the light is emitted as linearly polarized light in a vertical direction parallel to the vertical side of the spatial light modulation panel 200.

As described above, in order to effectively cause interference by combining two lights emitted from two neighboring pixels in the horizontal direction (horizontal direction) among the light linearly polarized in the vertical direction, in order to increase the efficiency, emitted from two neighboring pixels. It is preferable to make the linear polarization directions of the two light beams 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 column is changed to the horizontal linearly polarized state.

To this end, the first patterned half-wave plate PHW1 with the light transmission axis set in parallel with the direction of the vertical linear flat light in front of the odd pixel columns, and the light transmission axis 45 degrees in the direction of the vertical linear polarization in front of the even pixel columns. It is preferable to arrange the second patterned half-wave plate PHW2 set to be inclined. In FIG. 6, the first patterned half-wave plate PHW1 and the second patterned half-wave plate PHW2 are alternately arranged to correspond to the pixel columns of the spatial light modulation panel 200. BC). As shown in FIG. 6, the light of the pixel passing through the first patterned half-wave plate PHW1 maintains its original vertical linearly polarized state. On the other hand, the light of the pixel passing through the second patterned half wave plate PHW2 changes to a horizontal linearly polarized state. Therefore, the two phase-modulated lights emitted from two neighboring pixels in the horizontal direction are orthogonal to each other, and thus the interference efficiency is maximized. That is, the holographic stereoscopic image display device including the light coupling panel BC according to the present invention can further improve luminance and provide accurate stereoscopic images.

The light coupling panel BC according to the first embodiment is formed by patterning a half-wave plate in pixel column units. The direction of linear polarization 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. To this end, the direction of linearly polarized light is changed by delaying the phase of light emitted from neighboring pixel columns by lambda / 2 phase without maintaining the phase of light emitted from one pixel column and changing the direction of linearly polarized light. In other words, when fabricating and arranging a patterned half-wave plate for mutually orthogonal phases of two neighboring lights, it should be designed considering λ, which is the wavelength of light passing through the half-wave plate.

In the holographic stereoscopic image display device according to the first embodiment, the light is linearly polarized in the vertical direction in the spatial light modulation panel 200, and the linear polarization property of the light coupling panel BC is vertically and horizontally The adjustment is considered for the case of using a monochromatic light source. In particular, the case where the green light source having the wavelength of 532 nm is used is designed to have the maximum luminance in the front direction.

Since a holographic stereoscopic image display device that implements natural colors uses three primary light sources including red (red), green (green), and blue (blue), it is necessary to design to have the maximum luminance even in this case. In particular, since three subpixels of three primary RGB colors are gathered to form one pixel, a patterned half-wave plate commonly assigned to three subpixels in RGB should be designed. Hereinafter, referring to FIG. 7, a light coupling panel having an optimal light coupling efficiency in the case of using a three primary color light source will be described. 7 is a schematic view illustrating the structure and operation of a light coupling panel according to a 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 light linearly polarized in a direction inclined 45 degrees with respect to the vertical side of the spatial light modulation panel 200. The light emitted from the odd pixel columns among the linearly polarized light in the 45 degree direction changes the linear polarization state in the vertical direction, and the light emitted from the even pixel columns changes the linear polarization state in the horizontal direction.

To this end, a third patterned half-wave plate PHW3 is set in a direction in which the light transmission axis is inclined 67.5 degrees with respect to the horizontal side direction of the light coupling panel BC in front of the odd pixel column, and in front of the even pixel column. It is preferable to arrange the fourth patterned half-wave plate PHW4 whose axis is inclined 22.5 degrees with respect to the horizontal side direction of the light coupling panel BC. In FIG. 8, the third patterned half-wave plate PHW3 and the fourth patterned half-wave plate PHW4 are alternately arranged to correspond to the pixel columns of the spatial light modulation panel 200. BC).

As shown in FIG. 7, the light in the pixel column passing through the third patterned half-wave plate PHW3 changes from the linearly polarized state to the vertical linearly polarized state in the original 45 degree direction. On the other hand, the light of the pixel column passing through the fourth patterned half-wave plate PHW4 changes to a horizontal linearly polarized state. Therefore, the two phase-modulated lights emitted from two neighboring pixels in the horizontal direction are orthogonal to each other, and thus the interference efficiency is maximized. That is, the holographic stereoscopic image display device including the light coupling panel BC according to the second exemplary embodiment may further improve luminance and provide accurate stereoscopic images.

Hereinafter, a method of manufacturing the light 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 light coupling panel according to the present invention.

As shown in FIG. 8A, an alignment film ALG is coated on the transparent substrate SUB. The whole alignment film ALG is orientated in a 1st direction using the whole surface exposure method which irradiates the alignment film ALG with the ultraviolet-ray linearly polarized in the 1st direction. The horizontal arrow illustrated in FIG. 8A refers to the alignment pattern in the first direction formed on the alignment film ALG. In the case of the light coupling panel BC according to the first embodiment, the first direction is preferably set in the horizontal direction or the vertical direction. In the case of the light coupling panel BC according to the second embodiment, the first direction is It is preferable to set in the direction of 67.5 degrees with respect to the horizontal direction.

As shown in FIG. 8B, a part of the alignment film ALG is removed by using a partial exposure method that covers the mask MA on the alignment film ALG oriented in the first direction and irradiates ultraviolet rays linearly polarized in the second direction. The orientation direction is changed in two directions. The vertical direction arrow illustrated in FIG. 8B refers to the alignment pattern in the second direction formed on the alignment film ALG. In the case of the light coupling panel BC according to the first embodiment, the second direction is preferably set to 45 degrees with respect to the horizontal direction, and in the case of the light coupling panel BC according to the second embodiment, the second direction The direction is preferably set in the 22.5 degree direction with respect to the horizontal direction.

In this case, the pattern of the mask MA preferably corresponds to the pattern of the pixel column constituting the spatial light modulation panel 200. For example, the mask MA may be designed such that an odd numbered pixel column is assigned an alignment pattern in the first direction and an even pixel column is allocated an alignment pattern in the second direction. It is important to set so that there is 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, have their optical axes It is arranged at a 45 degree angle.

Thus, after forming the orientation pattern of a 1st direction in the whole orientation film ALG by the whole surface exposure method, the partial alignment method ALG of the some direction film in which the orientation pattern of the 1st direction was formed was made into the orientation pattern of a 2nd direction. Use the process of changing to have. For this purpose, it is preferable to use higher energy than partial exposure in partial exposure.

As illustrated in FIG. 8C, the reactive mesogen liquid crystal layer RM is coated on the entire surface of the alignment layer ALG having the alignment pattern in the first direction and the alignment pattern in the second direction. Ultraviolet rays are irradiated to the reactive mesogen liquid crystal layer RM to cure the reactive mesogen liquid crystal layer RM. Then, the reactive mesogenic liquid crystal layer RM is cured with a pattern in the same direction as the alignment pattern of the alignment film ALG. 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 positioned at a position corresponding to an even pixel column. Alternatively, the fourth patterned half wave plate PHW4 is formed.

Although not shown in the drawings, after curing the reactive mesogen liquid crystal layer RM, an antireflective coating layer is further formed on the rear surface of the substrate SUB, and a protective film is further attached to complete the final light coupling panel.

In this case, the thickness of the reactive mesogenic liquid crystal layer RM is Δn × d = λ / 2 (where Δn is the difference in refractive index anisotropy of the reactive mesogenic liquid crystal material, and λ is the wavelength of the polarization source). It is preferable to have a d value satisfying the condition of. In the first embodiment, as the case where green monochromatic light is used,? Is set to 532 nm. In addition, in the second embodiment using the three primary colors, it is preferable to set? As the reference based on 532 nm which is green light. However, in the first embodiment, in order to have the maximum transmittance, the green monochromatic light is linearly polarized in the vertical direction, the first direction is set in the horizontal direction or the vertical direction, and the second direction is set in the 45 degree direction with respect to the horizontal direction. It is desirable to. In addition, in the second embodiment, in order for all three color light sources to have the maximum transmittance, the tricolor light is linearly polarized in a direction inclined 45 degrees with respect to the horizontal direction, and the first direction has a direction of 67.5 degrees with respect to the horizontal direction. The two directions are preferably set to have a direction of 22.5 degrees with respect to the horizontal direction.

In addition, in Example 2 in which λ is set based on 532 nm, which is green light, linearly flat light may not be emitted in a direction of ± 45 degrees with respect to light of red and blue wavelengths. For this reason, when viewed from the front, a color shift phenomenon and / or front luminance may deteriorate in white light. This is because there is a difference in chromatic dispersion characteristics for each wavelength of RGB.

In order to solve this problem, in selecting a material of the reactive mesogen, it is preferable to use a reactive mesogen having reverse dispersion properties. Since reactive mesogens having reverse dispersion properties have an effect of reducing color dispersion than reactive mesogen materials having regular dispersion properties, color shift and brightness reduction problems due to color dispersion in the front direction are reduced. Table 1 below shows reactive mesos having inverse dispersion properties with respect to the front luminance values of a light coupling panel including reactive mesogens having normal dispersion properties when using white light having a wavelength of 125 nm and white light having a wavelength of 137 nm as a backlight. The change in the front luminance value of the light coupling panel including the gen is shown.

Reactive mesogen material Application of material properties 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

In Table 1, as can be seen, when the 125 nm light is transmitted using a light coupling panel including a reactive mesogen material having a dispersion property, the front luminance value is 150.0. As shown in Table 1, using a light coupling panel comprising reactive mesogen material having reverse dispersion properties, the front luminance value is improved by 1.7% compared to the reference value for 125 nm light and compared to the reference value for 137 nm light. It can be seen that the 4.3% improvement.

In selecting a substance of reactive mesogens, only reactive mesogens having normal or reverse dispersion properties may be selected and used, but reactive mesogens having normal dispersion properties and reactive mesogens having reverse dispersion properties are used. It can also mix and use. Most preferably, the content of the reactive mesogen material having anti-dispersion properties is preferably at least 25% of the total 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: spatial light modulator (SLM)
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 exit part IN: light exit part
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: light coupling BC: light coupling panel
SUB: Transparent substrate ALG: Alignment film
RM: reactive mesogen liquid crystal layer MA: mask
PHW1: first patterned half wave plate PHW2: second 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 in an area corresponding to a first pixel on the substrate; And
And a second patterned half-wave plate disposed in an area corresponding to a second pixel located on one side of the first pixel on the substrate.
The method of claim 1,
The first patterned half-wave plate is disposed in an area corresponding to an odd pixel column 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 of claim 1,
And the optical axes of the first patterned half-wave plate and the second patterned half-wave plate are offset by 45 degrees from each other.
The method of claim 3, wherein
The first patterned half-wave plate has an optical axis set parallel to the vertical side of the substrate,
The second patterned half-wave plate is a light coupling panel, characterized in that the optical axis is set in the direction inclined 45 degrees with respect to the horizontal side of the substrate.
The method of claim 4, wherein
And the display panel emits linearly polarized light from the pixels in a direction parallel to a vertical side of the substrate.
The method of claim 3, wherein
The first patterned half-wave plate is set in a direction in which the optical axis is inclined 67.5 degrees with respect to the horizontal side of the substrate,
The second patterned half-wave plate is a light coupling panel, characterized in that the optical axis is set in a direction inclined 22.5 degrees with respect to the horizontal side of the substrate.
The method according to claim 6,
And the display panel emits light linearly polarized from the pixels in a 45 degree direction with respect to a horizontal side of the substrate.
Applying an alignment layer on the transparent substrate;
Orienting the entire alignment layer in a first direction;
Reorienting a portion of the alignment layer exposed to the mask in a second direction that is shifted by 45 degrees with the first direction by using a mask having a matrix pattern on the alignment layer;
Applying a liquid crystal material on the alignment layer disposed such 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.
The method of claim 8,
And the liquid crystal material is coated with a thickness of d value satisfying Δn × d = λ / 2 (where Δn is the refractive index anisotropy of the liquid crystal material and λ is the wavelength of the green light).
The method of claim 8,
Wherein said liquid crystal material comprises at least 25% of reactive mesogen material having anti-dispersion properties.

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