KR20130106723A - Spatial light modulator using transparent type liquid crystal display panel based on thin film and 3d display device using the same - Google Patents

Abstract

PURPOSE: A spatial light modulator using a thin film-based transmissive liquid crystal display panel and a 3D display device using the same are provided to minimize the number of glass substrates by including a liquid crystal display panel for phase modulation and a liquid crystal display panel for amplitude modulation. CONSTITUTION: A light modulation panel (200) for phase modulation includes a lower film, an upper glass substrate, and a second liquid crystal layer. The upper glass substrate faces the lower film and is attached to the lower film. The second liquid crystal layer is interposed between the lower film and the upper glass substrate. A first polarization film is interposed between an upper film and the lower film and attaches a light modulation panel for amplitude modulation to the light modulation panel for the phase modulation.

Description

Spatial light modulator using thin film based transmissive liquid crystal display panel and stereoscopic image display device using the same {Spatial Light Modulator Using Transparent Type Liquid Crystal Display Panel Based On Thin Film And 3D Display Device Using The Same}

The present invention relates to a spatial light modulator using a thin film-based transmissive liquid crystal display panel and a stereoscopic image display device using the same. In particular, the present invention relates to a spatial light modulator using a thin film-based transmissive liquid crystal display panel applied to a holographic stereoscopic image display device and a stereoscopic image display device using 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.

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 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 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, a expander 40, and a lens 50 generating the reference light 90. 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. Since the two spatial light modulation panels are combined, it is difficult to align the two spatial light modulation panels. In addition, since two liquid crystal panels each using a thick glass substrate are used, a total of four glass substrates are used, so that the thickness is thick and the weight is heavy. In addition, since two sheets of thick glass are disposed to face each other while the two panels are bonded to each other, a change in image quality according to a viewing angle may occur.

An object of the present invention is to solve the above problems, to provide a spatial light modulator using a thin film-based liquid crystal display panel and a stereoscopic image display device using the same. Another object of the present invention is to fabricate an amplitude modulation liquid crystal display panel and a phase modulation liquid crystal display panel based on a thin film, and then a spatial light modulator of a thin film flat panel holographic stereoscopic image display apparatus using a bonded liquid crystal display panel. And to provide a three-dimensional image display device using the same.

In order to achieve the object of the present invention, the spatial light modulator according to the present invention, the lower glass substrate, the upper film bonded to face the lower glass substrate, the first liquid crystal interposed between the lower glass substrate and the upper film An amplitude modulation optical modulation panel comprising a layer; A phase modulation optical modulation panel including a lower film, an upper glass substrate bonded to the lower film, and a second liquid crystal layer interposed between the lower film and the upper glass substrate; And a first polarizing film interposed between the upper film and the lower film to bond the amplitude modulation light modulation panel and the phase modulation light modulation panel.

The lower glass substrate further includes a first lower alignment layer on an inner surface thereof; The upper film further includes a second lower alignment layer having an alignment direction parallel to an optical axis of the first polarizing film on an inner surface thereof.

The lower film further includes a first upper alignment layer having an alignment direction parallel to an optical axis of the first polarizing film on an inner surface thereof; The upper glass substrate may further include the second upper alignment layer on an inner surface thereof.

And a second polarizing film attached to the rear surface of the lower glass substrate and having an optical axis parallel to the alignment direction of the first lower alignment layer.

In addition, the holographic stereoscopic image display apparatus according to the present invention, the backlight unit for providing a backlight in one side direction; And a lower glass substrate, an upper film bonded to face the lower glass substrate, and a first liquid crystal layer interposed between the lower glass substrate and the upper film. A phase modulation optical modulation panel including a lower film, an upper glass substrate bonded to the lower film, and a second liquid crystal layer interposed between the lower film and the upper glass substrate; And a spatial light modulator interposed between the upper film and the lower film, the first polarizing film including the amplitude modulation light modulation panel and the phase modulation light modulation panel.

The lower glass substrate further includes a first lower alignment layer on an inner surface thereof; The upper film further includes a second lower alignment layer having an alignment direction parallel to an optical axis of the first polarizing film on an inner surface thereof.

The lower film further includes a first upper alignment layer having an alignment direction parallel to an optical axis of the first polarizing film on an inner surface thereof; The upper glass substrate may further include the second upper alignment layer on an inner surface thereof.

And a second polarizing film attached to the rear surface of the lower glass substrate and having an optical axis parallel to the alignment direction of the first lower alignment layer.

The backlight unit may be configured to linearly polarize the backlight in a direction parallel to the alignment direction of the first lower alignment layer, and to emit the backlight in a straight line toward the spatial light modulator.

The spatial light modulator and the stereoscopic image apparatus using the same according to the present invention include a phase modulation liquid crystal display panel and an amplitude modulation liquid crystal display panel manufactured based on a thin film. Therefore, the number of glass substrates for maintaining the rigidity of the liquid crystal display panel can be minimized. As the bonding thickness of the amplitude modulation panel and the phase modulation panel is thin, the alignment error can be minimized and the image quality change according to the viewing angle can be minimized. In addition, the thickness of the final light modulator in which the phase modulation panel and the amplitude modulation panel are bonded to each other can be made thin and light. In addition, the stereoscopic imaging apparatus according to the present invention can remove the polarizing plate from the spatial light modulator by using a backlight unit for generating linearly polarized laser light.

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.
2 is a schematic diagram showing the structure of a digital holography stereoscopic image display apparatus using a thin film film-based transmissive liquid crystal display panel according to the present invention.
3 is a cross-sectional view showing a structure of a spatial light modulator using a thin film film-based liquid crystal display panel according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, FIGS. 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 apparatus using a thin film film-based transmissive liquid crystal display panel as a spatial light modulator will be described. 2 is a schematic diagram showing the structure of a digital holography stereoscopic image display apparatus using a thin film film-based transmissive liquid crystal display panel according to the present invention.

The holographic stereoscopic image display device according to the present invention includes an optical modulator SL and a backlight unit BLU that provides a backlight under the optical modulator SL. In particular, the light modulator SL has a structure in which an amplitude modulating light modulator 100 and a phase modulating light modulator 200 are stacked. In order to make the amplitude modulating light modulator 100 and the phase modulating light modulator 200 into thin films, a transmissive liquid crystal display panel is formed.

The amplitude modulation SLM 100 has an upper film FU formed of a transparent thin film and a lower glass substrate GL formed of a transparent glass substrate facing each other, and a transmissive type having an IPS mode liquid crystal layer LA therebetween. It is formed of a liquid crystal display panel. Hereinafter, the present embodiment has been described as applying the IPS mode, which is a horizontal electric field method, to an amplitude modulation liquid crystal mode, but other horizontal electric field methods using a vertical electric field method or a fringe field may be applied. The amplitude modulation optical modulator 100 receives interference fringe pattern data from a computer or a video processing device (not shown) and displays the interference fringe. On the inner surfaces of the upper film FU and the lower glass substrate GL, a thin film transistor, a pixel electrode and a common electrode may be formed to drive the IPS mode liquid crystal layer LA, which is an amplitude modulation liquid crystal layer.

The phase modulation optical modulator 200 has an ECB mode liquid crystal layer LP interposed therebetween when the upper glass substrate GU formed of a transparent glass substrate and the lower film FL formed of a transparent thin film face each other. It is formed by one transmissive liquid crystal display panel. The phase modulation optical modulator 200 also receives interference fringe pattern data from a computer or a video processing device (not shown) and displays the interference fringe. On the inner surfaces of the upper glass substrate GU and the lower film FL, a thin film transistor, a pixel electrode and a common electrode may be formed to drive the ECB mode liquid crystal layer LP, which is a phase modulation liquid crystal layer.

In addition, the backlight unit BLU disposed on the lower surface of the light modulator SL includes a light source 300 and an optical fiber OF. 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 optical modulator SL. For example, laser diodes R, G, and B may be disposed on one side of the backlight unit BLU. In addition, the laser beams emitted from the laser diodes R, G, and B may be extended from the lower surface of the optical modulator SL by using the optical fiber OF. The optical fiber OF may be disposed to correspond to the front surface of the optical modulator SL, 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, the optical sheet 500 which adjusts the reference light extended by the optical fiber OF to maintain the size corresponding to the area of the optical modulator SL and runs parallel to the optical modulator SL and the optical fiber OF It may further include in between.

In the present embodiment, the backlight unit BLU discloses only a schematic structure using the optical fiber OF. When the color pixels constituting the optical modulator SL 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.

Hereinafter, the spatial light modulator SL, which is a key component of the present invention, will be described in detail with reference to FIG. 3. 3 is a cross-sectional view illustrating a structure of a spatial light modulator using a thin film based liquid crystal display panel according to the present invention.

The spatial light modulator SL according to the present invention has a structure in which an amplitude modulation light modulator 100 and a phase modulation light modulator 200 are stacked. The amplitude modulating optical modulator 100 is responsible for modulating the intensity of light, that is, the contrast, and includes a liquid crystal layer LA of an in-plane switching (IPS) mode driven by a horizontal electric field. It consists of. On the other hand, the phase modulation optical modulator 200 is responsible for modulating the phase of light passing through a given pixel, the liquid crystal including a liquid crystal layer LP of the electrically controlled birefingence (ECB) mode driven by a vertical electric field It consists of a display panel. 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. That is, when the wavelength of light is λ, the thickness of the liquid crystal layer LP is selected to satisfy Δn · d = λ.

The amplitude modulating light modulator 100 includes a lower glass substrate GL made of transparent glass, an upper film made of a transparent thin film FU, and an IPS mode liquid crystal layer LA driven by a horizontal electric field interposed therebetween. It includes. A first thin film transistor layer TFT1 including a pixel electrode for forming a horizontal electric field, a common electrode, and a thin film transistor for driving the pixel electrode is formed on an upper surface corresponding to an inner surface of the lower glass substrate GL. The lower surface corresponding to the inner surface of the upper film FU may include a color filter for implementing a color. In order to set an initial alignment state of the IPS mode liquid crystal layer LA interposed between the lower glass substrate GL and the upper film FU, a first lower alignment layer AL1 is disposed on the first thin film transistor layer TFT1. The inner lower surface of the upper film FU may further include a second lower alignment layer AL2.

The phase modulating light modulator 200 includes a lower film FL made of a transparent thin film, an upper glass substrate made of transparent glass, and an ECB mode liquid crystal layer LP driven by a vertical electric field interposed therebetween. It includes. A second thin film transistor layer TFT2 including a pixel electrode for forming a vertical electric field and a thin film transistor for driving the pixel electrode is formed on a lower surface corresponding to an inner surface of the upper glass substrate GU. A common electrode COM is formed on the upper surface corresponding to the inner surface of the lower film FL to form a vertical electric field facing the pixel electrode. Since the phase modulating light modulator 200 does not adjust the contrast of colors, it is preferable not to include a color filter. In order to set the initial alignment state of the ECB mode liquid crystal layer LP interposed between the upper glass substrate GU and the lower film FL, a first upper alignment layer AU1 is drawn on the upper surface of the lower film FL. The second upper alignment layer AL2 may be further included on the second thin film transistor layer TFT2.

The optical modulator SL according to the present invention represents a stereoscopic image by modulating an amplitude and a phase by using a linearly polarized laser light. For example, when the amplitude modulation optical modulator 100 is implemented in an IPS mode to which a normally white condition is applied, the amplitude modulation optical modulator 100 is formed between two polarizing films having light transmission axes parallel to each other. It is preferable to place in. That is, the lower polarizing film POL is disposed on the rear surface of the amplitude modulating light modulator 100 and the upper polarizing film POU is disposed on the upper surface thereof, and these light transmission axes are preferably parallel to each other. As another example, when the amplitude modulated optical modulator 100 is implemented in the IPS mode to which the normally black condition is applied, the amplitude modulated optical modulator 100 is disposed between two polarizing films whose optical transmission axes are perpendicular to each other. It is preferable to arrange. That is, the lower polarizing film POL is disposed on the rear surface of the amplitude modulating light modulator 100, and the upper polarizing film POU is disposed on the upper surface thereof, and these light transmission axes are preferably perpendicular to each other. As another example, when the amplitude modulation optical modulator 100 is implemented in a TN mode to which a normally white condition is applied, the amplitude modulation optical modulator 100 is formed between two polarizing films whose light transmission axes are perpendicular to each other. It is preferable to place in. That is, the lower polarizing film POL is disposed on the rear surface of the amplitude modulating light modulator 100, and the upper polarizing film POU is disposed on the upper surface thereof, and these light transmission axes are preferably perpendicular to each other.

In any combination, since the optical modulator SL based on the liquid crystal display panel according to the present invention uses linear polarization, it is preferable to linearly polarize the light emitted from the backlight unit BLU. That is, the output polarization direction of the backlight unit BLU goes straight in parallel toward the spatial light modulator 100 so that the polarization direction is linearly polarized in a direction parallel to the initial arrangement direction of the liquid crystal layer LA of the amplitude modulation optical modulator 100. It is desirable to exit the company. Therefore, the light transmission axis of the lower polarizing film POL is related to the initial arrangement direction of the amplitude modulation liquid crystal layer LA. In particular, it is related to the initial arrangement direction of the liquid crystal molecular layer arranged to be adjacent to the lower glass substrate GL, which is the side where the line polarization is incident. In addition, the light transmission axis of the upper polarizing film POU is also related to the initial arrangement direction of the liquid crystal layer LA for amplitude modulation, particularly the liquid crystal molecular layer arranged to be adjacent to the upper film FU. That is, the alignment direction of the first lower alignment layer AL1 is parallel to the light transmission axis of the lower polarizing film POL, and the alignment direction of the second lower alignment layer AL2 is the light transmission axis of the upper polarizing film POL. Is preferably parallel to

On the other hand, the phase modulation optical modulator 200 phase modulates the linearly polarized laser light after passing through the upper polarizing film POU by using the liquid crystal layer LP of the ECB mode. Therefore, the alignment direction of the first upper alignment layer AU1 is preferably parallel to the light transmission axis of the upper polarizing film POU. Since the phase modulated light modulator 200 according to the present embodiment operates with a vertical electric field using the ECB mode liquid crystal layer LP, after passing through the phase modulated light modulator 200, the polarization direction of polarization does not change. Do not. Therefore, it is preferable that the alignment direction of the second upper alignment layer AU2 is parallel to the alignment direction of the first upper alignment layer AU1. However, in some cases, when it is necessary to use elliptical polarization or circular polarization, the liquid crystal layer of another mode may be used in the phase modulation optical modulator 200, in which case, the second upper alignment layer AU2 is used. And orientation directions of the first upper alignment layer AU1 may be different.

In the case described above, the case where the backlight unit BLU for emitting general laser light is used is described. However, when the backlight unit BLU provides linear polarization by itself, the lower polarizing film POL may be omitted.

In the bonding of the amplitude modulating light modulator 100 and the phase modulating light modulator 200 having such a structure, it is preferable to bond the upper film FU and the lower film FL, which are transparent thin films, to face each other. Do. In particular, it is preferable to bond the upper polarizing film POU therebetween. The material of the upper film (FU) and the lower film (FL), it is preferable to include a polycarbonate (Polycarbonate) or polyimide (Polyimide) excellent in process stability and thermal stability. As a result, in the final spatial light modulator SL in which the amplitude modulating light modulator 100 and the phase modulating light modulator 200 are bonded, two glass substrates GL and GU are bonded together, and the amplitude modulating light interposed therebetween. Liquid crystal layer LA) and a liquid crystal layer LP for phase modulation. Since transparent thin film films FL and FU are relatively thinner than that of a glass substrate, a thin and light light modulator may be provided. In addition, since the thin films are bonded together, it is possible to minimize the occurrence of errors in aligning the pixels of the two liquid crystal panels. In addition, the bonding distance between the two optical modulators is minimized so that the image quality does not change according to the viewing angle.

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, SL: Spatial Light Modulator (SLM)
30, 300: laser light source 40: expander
50: Lens 80: Output image
90: reference light 500: optical sheet
BLU: backlight unit R: red laser diode
G: green laser diode B: blue laser diode
OF: optical fiber OUT: optical exit part
IN: light incident part 500: optical film
100: optical modulator for amplitude modulation GL: lower glass substrate
FU: upper film LA: IPS mode liquid crystal layer
TFT1: first thin film transistor layer AL1: first lower alignment layer
AL2: second lower alignment layer
200: optical modulator for phase modulation GU: upper glass substrate
FU: upper film LP: ECB mode liquid crystal layer
TFT2: second thin film transistor layer COM: common electrode
AU1: first upper alignment layer AU2: second upper alignment layer
POL: lower polarizing film POU: upper polarizing film

Claims (9)

An amplitude modulation optical modulation panel including a lower glass substrate, an upper film bonded to the lower glass substrate, and a first liquid crystal layer interposed between the lower glass substrate and the upper film;
A phase modulation optical modulation panel including a lower film, an upper glass substrate bonded to the lower film, and a second liquid crystal layer interposed between the lower film and the upper glass substrate; And
And a first polarizing film interposed between the upper film and the lower film to bond the amplitude modulation light modulation panel and the phase modulation light modulation panel.
The method of claim 1,
The lower glass substrate further includes a first lower alignment layer on an inner surface thereof;
And the upper film further includes a second lower alignment layer having an alignment direction parallel to an optical axis of the first polarizing film on an inner surface thereof.
The method of claim 1,
The lower film further includes a first upper alignment layer having an alignment direction parallel to an optical axis of the first polarizing film on an inner surface thereof;
The upper glass substrate further comprises a second upper alignment layer on an inner surface thereof.
The method of claim 1,
And a second polarizing film attached to a rear surface of the lower glass substrate, the second polarizing film having an optical axis parallel to the alignment direction of the first lower alignment layer.
A backlight unit for providing a backlight in one side direction; And
An amplitude modulation optical modulation panel including a lower glass substrate, an upper film bonded to the lower glass substrate, and a first liquid crystal layer interposed between the lower glass substrate and the upper film; A phase modulation optical modulation panel including a lower film, an upper glass substrate bonded to the lower film, and a second liquid crystal layer interposed between the lower film and the upper glass substrate; And a spatial light modulator including a first polarizing film interposed between the upper film and the lower film to bond the amplitude modulation light modulation panel and the phase modulation light modulation panel. Stereoscopic image display.
The method of claim 5, wherein
The lower glass substrate further includes a first lower alignment layer on an inner surface thereof;
And the upper film further comprises a second lower alignment layer having an alignment direction parallel to an optical axis of the first polarizing film on an inner surface thereof.
The method of claim 5, wherein
The lower film further includes a first upper alignment layer having an alignment direction parallel to an optical axis of the first polarizing film on an inner surface thereof;
The upper glass substrate further comprises a second upper alignment layer on an inner surface thereof.
The method of claim 5, wherein
And a second polarizing film attached to a rear surface of the lower glass substrate, the second polarizing film having an optical axis parallel to the alignment direction of the first lower alignment layer.
The method of claim 5, wherein
And the backlight unit linearly polarizes the backlight in a direction parallel to the direction in which the first lower alignment layer is aligned, and emits the backlight in a straight line toward the spatial light modulator.

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