KR20150077180A - Dynamic Thin Flat Type Light-Beam Deflector - Google Patents

Abstract

The present invention relates to an active thin flat type optical deflector. The optical deflector by an embodiment of the present invention includes: an active four half-wave delay plate which changes linearly polarized light into one polarized state of first circularly polarized light and second circularly polarized light; and a first optical path conversion cell which forms one of a first prism pattern and a second prism pattern. The active thin flat type optical deflector minimizes stress which liquid crystal molecules suffer from.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an active thin film flat-type optical deflector,

The present invention relates to an active thin film flat plate type optical deflecting device. In particular, the present invention relates to a three-dimensional image device for restoring / reproducing a digital hologram image, an active thin film flat panel (hereinafter, referred to as " thin film flat panel ") for application to eye tracking for adjusting the image focus to the viewers' Type optical deflecting device.

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 an object to collide with a reference wave incident from another direction is recorded on the scattered film by using a highly coherent laser beam. 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 three-dimensional image device by the hologram method according to FIG. 1 is a non-eyeglass stereoscopic image display device. In the non-eyeglass stereoscopic image display apparatus, a stereoscopic image can be viewed only when the stereoscopic image is focused within the field of view of the spectator. Particularly, in the three-dimensional stereoscopic image by the hologram method, an image is formed at a position where the spectator can observe the space between the display device and the spectator. Therefore, it is necessary to adjust the focus position of the hologram image so that the viewer moves in parallel when the viewer moves the position.

Various optical deflecting devices have been proposed so far. Typically, an optical deflecting device by a holography method or an optical deflecting device by a phase mask method has been proposed. However, since these optical deflecting devices have only a fixed deflection angle, they can not actively deflect light according to the moving position of the viewer.

On the other hand, a photo-polarizing apparatus using a refractive index difference of liquid crystal has been proposed. See, for example, U.S. Pat. Nos. 3,843,231 and 4,850,682. They can adjust the extent of the deflection angle to some extent, but the deflection angle range is extremely limited due to the structural limitations. Especially, in a large display device such as a TV, when a viewer moves a considerable distance from the left to the right, it can not deflect light in a large angle range. However, in US 3,843,231 it has only a fixed deflection angle and can not actively deflect light. Furthermore, in the case of US 4,850,682, there is also a manufacturing process and a cost problem in which the surface of the substrate must be precisely machined.

Therefore, in order to provide a correct stereoscopic image in a non-eyeglass type three-dimensional image display apparatus, there is a need for an optical deflector for tracking a position change of a viewer and deflecting a focus position of an image in a parallel direction. Particularly, a light deflector which is an active type and thin plate type which can be effectively applied to a thin film type stereoscopic image device is also needed.

Hereinafter, an optical deflecting device using a liquid crystal display panel will be described. 2 is a perspective view showing an example of application to a stereoscopic image display apparatus of a non-eyeglass system, as an example of an optical deflecting apparatus using a liquid crystal display panel according to the related art. 2, the hologram image system according to the related art includes a hologram display panel 100, a light path changing cell 300 including first and second light path changing cells 300a and 300b, A driving unit 500, an optical path conversion cell driving unit 600, a control unit 800, and a sensing camera 900.

The hologram display panel 100 may be configured in the same manner as the above-described configuration in Fig. For example, the hologram display panel 100 may be a transmissive LCD (Liquid Crystal Display). The hologram display panel 100 receives and displays an interference fringe pattern, and thus the light emitted from the laser light source passes through the hologram display panel 100, and the hologram image is displayed in the other direction of the display panel 100 .

The first light path changing cell 300a is disposed in front of the display panel 100 in a direction (+ z-axis direction in the figure) in which the light advances. The first optical path changing cell 300a passes the light incident from the display panel 100 as it is or forms a prism pattern in a horizontal direction (x-axis direction in the drawing) Refract light in the downward direction (-φ) (y-axis direction in the drawing). Therefore, the generation position of the hologram image 400 in the up / down direction can be adjusted by the first light path changing cell 300a.

A second optical path changing cell 300b is further disposed in front of the first optical path changing cell 300a. The second optical path changing cell 300b passes the light from the first optical path changing cell 300a as it is or forms a prism pattern in a vertical direction (y-axis direction in the drawing) ) Or the right direction (+ [theta]) (relative to the x-axis direction in the drawing). Therefore, the generation position of the hologram image 400 can be adjusted in the horizontal axis (x axis) direction, i.e., the left / right direction by the second optical path changing cell 300b.

The display panel driver 500 includes a gate driver and a data driver. The data driver receives the hologram data DATA from the controller 800 and receives the hologram data DATA from the positive / negative polarity gamma compensation voltage supplied from a gamma voltage generator circuit (not shown) To an analog data voltage. The data driver supplies the positive / negative analog data voltages to the data lines of the display panel 100. The gate driver sequentially supplies gate pulses (or scan pulses) synchronized with the data voltage to the gate lines of the display panel 100 under the control of the controller 800. [

The light path conversion cell driver 600 supplies the driving voltage for driving the light path conversion cell 300 to the first light path conversion cell 300a and the second light path conversion cell 300b, respectively. This driving voltage can display the hologram image 40 in accordance with the user's position by adjusting the slope value of the prism patterns formed in the optical path conversion cell. The driving voltage may be a set of voltages that linearly decrease or increase in order to linearly adjust the alignment direction of the liquid crystal molecules constituting the liquid crystal cell.

The control unit 800 controls the display panel driving unit 500 to drive the display panel 100. The control unit 800 supplies the gate driving unit control signal GCS to the gate driving unit and the hologram data DATA and the data driving unit control signal DCS to the data driving unit. The gate driver control signal GCS may include a gate start pulse, a gate shift clock, and a gate output enable signal. The data driver control signal DCS may include a source start pulse, a source sampling clock, a source output enable signal, a polarity control signal POL, and the like.

The sensing camera 900 captures an image of the user and transmits the sensed image to the control unit 800. The control unit 800 analyzes the photographed image and calculates coordinates at which the user is located. The controller 800 compares the calculated position coordinates of the user with the reference point and determines how much the user has moved in the left / right and up / down directions with respect to the reference point. The control unit 800 controls the optical path conversion cell driving unit 600 based on the position information to generate a prism pattern having a predetermined slope value in the first optical path conversion cell 300a and the second optical path conversion cell 300b, And the driving voltage is supplied to the gate electrode.

The prism pattern formed in the optical deflector using the liquid crystal display panel maintains the same pattern as long as the position of the spectator does not change. That is, the liquid crystal molecules have the same state for a long period of time. This means that the voltage applied to the liquid crystal molecules is maintained at the same value for a long time. When the same state is kept for a long time while the liquid crystal molecules continue to receive the same voltage difference, there is a high possibility that the liquid crystal molecules are deteriorated. That is, the performance of the optical deflecting device tends to deteriorate, and the life span can be shortened.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin film optical deflecting device which is designed to overcome the above-described problems and which minimizes stress applied to liquid crystal molecules by applying different voltages to each liquid crystal cell every frame. Another object of the present invention is to provide a thin film optical deflecting device which prevents deterioration of liquid crystal molecules by keeping the absolute value of the voltage applied to the liquid crystal cell the same but changing the direction so that the total average voltage value is always zero .

In order to achieve the object of the present invention, an optical deflecting device according to an embodiment of the present invention includes: an active quadruple wavelength delay plate for converting a linearly polarized light into a first circularly polarized light and a second circularly polarized light; And a first light path changing cell forming one of a first prism pattern and a second prism pattern.

During a period in which the active quadruple wavelength delay plate converts the linearly polarized light to the first circular polarization state, the first optical path changing cell forms the first prism pattern; And the first optical path changing cell forms the second prism pattern while the active quadruple wavelength delay plate changes the linearly polarized light to the second circularly polarized light state.

The first circularly polarized light is left-handed circularly polarized light, the second circularly polarized light is right-handed circularly polarized light, and the first prismatic pattern deflects the left-circularly polarized light in a horizontal direction by a refraction angle? And the second prism pattern deflects the right-handed polarized light in the horizontal direction by the refraction angle &thetas;.

Wherein the first optical path changing cell comprises HAN mode liquid crystal molecules and the voltage forming the first prism pattern is the same as the absolute value of the voltage forming the second prism pattern, do.

The optical deflecting device according to another embodiment of the present invention may further include a second optical path changing cell forming one of a third prism pattern and a fourth prism pattern.

The second optical path changing cell forms the third prism pattern while the active quarter wave retarder changes the linearly polarized light to the first circularly polarized light state; And the second optical path changing cell forms the fourth prism pattern while the active quarter wave retarder changes the linearly polarized light to the second circularly polarized light state.

Wherein the first circularly polarized light is left-handed circularly polarized light, the second circularly polarized light is right-handed circularly polarized light, and the third prismatic pattern deflects the left-circularly polarized light vertically by a refraction angle? And the second prism pattern deflects the right-handed polarized light in the vertical direction by the refraction angle?.

Wherein the second optical path changing cell comprises HAN mode liquid crystal molecules and the voltage forming the third prism pattern is the same as an absolute value of a voltage forming the fourth prism pattern, do.

The optical deflection apparatus according to the present invention changes the voltage applied to the optical path conversion cell every frame. Accordingly, it is possible to prevent the liquid crystal molecules from being deteriorated or damaged by neutralizing the voltage stress to which the liquid crystal molecules are subjected. Further, in order to compensate for the change in the refraction direction caused by changing the voltage applied to the liquid crystal molecules, the active quadruple wavelength retardation plate can be used to deflect light in the same direction in all the frames.

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.
Fig. 2 is a perspective view showing an example of application to a stereoscopic image display apparatus of a non-eyeglass system, as an example of an optical deflecting apparatus using a liquid crystal display panel according to the related art.
3 is a schematic view showing a driving method of a thin film flat plate type optical deflecting device according to the first embodiment of the present invention.
4 is a schematic view showing a driving method of a thin film flat plate type optical deflecting device according to a second embodiment of the present invention.
FIG. 5 is a schematic view showing a shape of a prism pattern and a traveling direction of light realized in a thin film flat plate type optical deflecting device by a driving method according to FIG. 4;
6 is a perspective view showing an example of a stereoscopic image display apparatus of a non-eyeglass system applying a thin film flat plate type optical deflecting apparatus according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the component names used in the following description may be selected in consideration of easiness of specification, and may be different from the parts names of actual products.

Referring to Fig. 3, the thin film flat plate type optical deflecting device according to the first embodiment of the present invention will be described. 3 is a schematic view showing a driving method of the thin film flat plate type optical deflecting device according to the first embodiment of the present invention. The basic structure of the thin film flat plate type optical deflecting device according to the first embodiment is almost the same as that of the prior art. If there is a difference, there is a difference in the manner of implementing the prism pattern in the liquid crystal display panel. Therefore, a description will be made by omitting redundant description and focusing on a method of forming a prism pattern.

The thin film flat plate type optical deflecting device using a liquid crystal display panel includes a light path changing cell 300 for making a pattern (also referred to as a prism pattern) that performs the same operation as a prism using the difference in refractive index of liquid crystal. As described above, the users who use the display device are in almost the same position, and their positions do not change frequently. Therefore, the prism pattern does not change greatly. In other words, most of the liquid crystal molecules in the light path changing cell 300 often hold substantially the same posture for a long time. As a result, the liquid crystal molecules can be deteriorated.

In order to prevent this, in the optical deflecting device according to the first embodiment of the present invention, by using a method of scanning the prism pattern in one direction while maintaining the optical deflection angle of the prism pattern, And a light path conversion cell 300 that is driven to change the light path. Will be described in more detail with reference to FIG.

For example, it is assumed that a prism pattern is defined by five consecutive pixels (or liquid crystal cells) of the light path changing cell 300. At this time, in the first frame, the liquid crystal molecules of the pixels may be arranged as in <Frame 1> of FIG. Arrangement of Pixels The graphs shown below show examples of prism shapes according to the arrangement of liquid crystal molecules.

In the second frame, which is the next frame, the liquid crystal molecule arrangement of the pixels is changed by changing the electric field like < Frame 2 >. As in the graph shown below the pixel array, the prism shape changes to the same shape as shifted by two pixels to the right. However, since the bent angle of the prism is maintained, the progress direction of light through the light path changing cell 300 is not changed even if the first frame is changed to the second frame. If the observer's position changes in the second frame to change the direction of the light, the angle of the prism can be changed by changing the magnitude of the voltage applied to each pixel. Here, the case of changing the deflection angle of light is not described for convenience.

In the third frame, which is the next frame, the electric field is changed as in < Frame 3 >. At this time, the absolute value is the same but the electric field value is changed so that the sign is changed. As a result, the alignment direction of the liquid crystal molecules is not changed. However, since the direction of the electric field received by the liquid crystal molecules changes, the electric field stress applied to the liquid crystal molecules may act differently. That is, the posture of the liquid crystal molecules is not changed, and the magnitude of the absolute value of the electric field is not changed, but the stress to which the liquid crystal molecules are subjected can be reduced. And the third frame has the same prism pattern and arrangement order as in the second frame.

Finally, in the fourth frame, the electric field is changed as in < Frame 4 >. As in the graph shown below the pixel array, the prism shape changes to the same shape as shifted by two pixels to the right. The magnitude of the absolute value of the electric field applied to each pixel in the fourth frame is equal to the magnitude of the absolute value of the electric field of the first frame, but the direction of the electric field is changed.

By applying the other electric field in the four frames in this way, the deflection angle is kept constant, but by scanning the prism pattern in one direction, it is possible to place the liquid crystal molecules in each pixel in a state of being subjected to an electric field which changes at any time. What is important here is that the sum of the electric field applied for a period of four frames in one pixel should be zero ('0'). That is, when the sum of the average electric fields is zero-sum, the liquid crystal molecules can minimize the electric field stress.

However, by observing FIG. 3 in detail, the sum of the electric fields applied to all the pixels during the four-frame period is not zero. For example, since the first pixel is changed to 0, + V2, -V2, and 0, the sum of the electric fields applied during the 4-frame period becomes zero. However, in the case of the third pixel, which is marked with *, it is changed to + V2, 0, 0, + V2, so that the sum of the electric fields applied during the 4-frame period becomes +2V2. That is, it is not zero. Similarly, even in the case of the seventh pixel having the mark *, the sum of the electric fields applied during the four-frame period becomes +2V2.

According to the first embodiment of the present invention, the average value over the entire frame of the electric field applied to most of the pixels can be set to zero. However, some of the pixels still retain non-zero values, so that some liquid crystal molecules may deteriorate. As described above, when a certain small number of pixels are intensively deteriorated, the performance difference between the pixels may become more conspicuous.

In the second embodiment of the present invention, referring to FIGS. 4 and 5, unlike the first embodiment, the total sum (or the average value) over all the frames of the electric field applied to all liquid crystal pixels is driven to be zero An example of the optical deflecting device will be described. 4 is a schematic view showing a driving method of the thin film flat plate type optical deflecting apparatus according to the second embodiment of the present invention. 5 is a schematic view showing a shape of a prism pattern and a traveling direction of light realized in a thin film flat plate type optical deflecting device by a driving method according to FIG.

The thin film optical deflecting device according to the second embodiment uses a light path conversion cell 300 to which a liquid crystal material of a hybrid aligned nematic (HAN) mode is applied. The thin-film optical deflecting device according to the second embodiment operates in an odd-numbered frame and an even-numbered frame in synchronism with the frame method in which the display device operates.

For example, the light path conversion cell 300 may form a prism pattern over seven consecutive pixels P1 to P7. As shown in FIG. 4, when the arrangement of the liquid crystal molecules LCM is arranged to sequentially change from the 0 degree direction to the 180 degree direction over seven consecutive pixels P1 through P7, (P1 to P7) can act in the same manner as the prism patterns sequentially changed in phase difference from 0 to 2? As shown in Fig.

In the case of an odd-numbered frame, an electric field can be applied in the same manner as the < ODD Frame > shown in Fig. 4, the HAN mode liquid crystal molecules LCM are placed in the pixels P1 to P7 constituting the optical path changing cell 300. [ In the first pixel P1, when the liquid crystal molecule LCM is 180 占 퐉, the direction from the end indicated by the vertical line segment (|) to the end indicated by the dotted line () Direction. The arrows shown inside the liquid crystal molecules LCM mean the alignment directions of the liquid crystal molecules. A voltage is applied so that the liquid crystal molecules LCM of the seven consecutive pixels P1 to P7 are arranged in a sequential arrangement direction from 180 degrees to 0 degrees. As a result, the relative phase modulation values of the liquid crystal molecules LCM from the first pixel P1 to the seventh pixel P7 sequentially change from 0 to 2 ?. That is, a relative phase difference graph can be drawn as shown in <ODD Frame> in FIG. This relative phase difference graph may correspond to a prism shape having a left inclined plane.

In the case of an even-numbered frame, an electric field can be applied in the same manner as the < EVEN Frame > shown in Fig. 4, the HAN mode liquid crystal molecules LCM are placed in each of the pixels P1 to P7 of the optical path changing cell 300. In FIG. In the first pixel P1, when the liquid crystal molecule LCM is 0 (zero), the direction from the end indicated by the vertical line segment (|) to the end indicated by the dotted line (? Direction. A voltage is applied so that the liquid crystal molecules LCM of the seven consecutive pixels P1 to P7 are arranged in a sequential arrangement direction from 0 to 180 degrees. As a result, the relative phase modulation values of the liquid crystal molecules LCM from the first pixel P1 to the seventh pixel P7 sequentially change from 2? To 0. That is, a relative phase difference graph can be drawn as shown in <EVEN Frame> of FIG. This relative phase difference graph may correspond to a prism shape having a right sloped surface.

In this way, in the optical path changing cell 300 using the HAN mode liquid crystal material, the absolute values of the electric fields in the odd frame and the even frame are the same, but the direction of the electric field is reversely applied so that the stress applied to the liquid crystal molecules Can be changed. That is, the total sum (or average field value) of the electric field during the entire frame period becomes zero. Particularly, the average electric field value can be made zero in all the pixels of the liquid crystal panel.

However, as shown in Fig. 5, the shapes of the odd-numbered frames whose directions are opposite to each other and the shapes of the prism patterns formed by even-numbered frames are inclined in opposite directions. If the prism pattern has the opposite shape, a 90 degree difference in the refraction direction of the light passing therethrough occurs. That is, the direction of light deflection changes in the opposite direction. In order to prevent this, that is, to maintain the same deflection direction even if the frame changes, it is necessary to change the polarization direction of the incident light.

5, in the odd frame, when the incident light 100 is incident in the right circularly polarized state, the outgoing light 200 deflected by the frame prism pattern having the left-side sloped surface is incident on the right- And is emitted in a polarized state. On the other hand, in the even-numbered frame, when the incident light 100 enters the left-handed circularly polarized state, the outgoing light 200 deflected by the frame prism pattern having the right-side slanted surface is emitted in the right-handed circularly polarized state deflected to the right by?. In other words, although the prism patterns formed in the odd-numbered frames and the prism patterns formed in the even-numbered frames are different by 90 degrees, the directions of the outgoing light refracted and proceeded are the same because the polarization states of the incident light 100 are opposite to each other.

Therefore, the thin-film optical deflecting device according to the second embodiment of the present invention includes an optical path changing cell 300 having HAN mode liquid crystal molecules, and an optical path changing cell 300 disposed below the optical path changing cell 300 and changing the polarization state of incident light It is preferable to have an active quarter wave plate (AQP).

In the above description, only one optical path conversion cell 300 is described. When this is applied to a display device, the optical path can be converted only in the left-right direction or only in the up-down direction. In order to convert the optical path in both left and right and up and down directions, the optical path conversion cell 300 includes a first optical path conversion cell for converting the optical path in the left-right direction and a second optical path conversion cell for converting the optical path in the up- . That is, the first optical path changing cell forms a first prism pattern formed in the longitudinal direction, and the second optical path changing cell forms a second prism pattern formed in the transverse direction, which is a direction orthogonal to the first prism pattern .

Hereinafter, a stereoscopic image display apparatus of a non-eyeglass system using a thin film optical deflecting apparatus according to a second embodiment of the present invention will be described. 6 is a perspective view showing an example of a stereoscopic image display apparatus of the non-eyeglass system applying the thin film flat plate type optical deflecting apparatus according to the second embodiment of the present invention. The image can be transmitted according to the position of the viewer by using the first light path conversion cell 300a and the second light path conversion cell 300b in which two light path conversion cells 300 described above are combined to be orthogonal to each other .

6, a stereoscopic image display apparatus using a thin film optical deflecting apparatus according to a second embodiment of the present invention includes a backlight unit (BLU), a display panel 100 for displaying a holographic stereoscopic image, an active quarter wave retardation The plate AQP, the first optical path changing cell 300a, and the second optical path changing cell 300b are sequentially arranged. The backlight unit (BLU) is preferably a thin film backlight unit. The display panel 100 is preferably a liquid crystal display panel in which a hologram pattern is displayed, and the light emitted from the backlight unit (BLU) displays a stereoscopic image by a hologram pattern.

Therefore, the backlight emitted from the backlight unit BLU may be light in a non-polarized state. However, the light emitted from the display panel 100 is light polarized in one direction. Here, it is assumed that the display panel 100 outputs light linearly polarized in the vertical direction. For example, when an image of an odd frame is displayed on the display panel 100, linearly polarized light is emitted in the vertical direction.

During the odd frame period, the active quarter wavelength retardation plate (AQP) is adjusted to have a polarization state of 45 degrees. As a result, light that is linearly polarized in the vertical direction can pass through the active quadruple wavelength delay plate (AQP) and can be right-handed circularly polarized. The right circularly polarized light is deflected laterally by the first optical path changing cell 300a. In other words, it is refracted at an angle (?) Bent on the X axis in the coordinate system of FIG. 6 and proceeds. In particular, the first optical path changing cell 300a can drive a liquid crystal using a positive potential difference to form a prism pattern having a left surface inclined surface. At this time, since the first optical path changing cell 300a is also a type of liquid crystal display panel and has a half-wavelength retardation function, the light passing through the first optical path changing cell 300a becomes a left circularly polarized state. The left circularly polarized light is deflected upward and downward by the second optical path changing cell 300b. That is, in the coordinate system of FIG. 6, the light beam is refracted at an angle? That is, light having stereoscopic image information traveling in the Z direction is deflected toward a desired position on the X axis and the Y axis. In particular, the second optical path changing cell 300b can drive a liquid crystal using a negative potential difference to form a prism pattern having a top surface inclined surface.

During the even frame period, the active quarter wave retarder (AQP) is adjusted to have a polarization state of 135 degrees. As a result, light that is linearly polarized in the vertical direction can be left-pivoted when passing through the active quarter wave retardation plate (AQP). Then, the left-handed circularly polarized light is deflected laterally by the first optical path changing cell 300a. In other words, it is refracted at an angle (?) Bent on the X axis in the coordinate system of FIG. 6 and proceeds. In particular, the first optical path changing cell 300a can form a prism pattern having a right side slope by driving the liquid crystal using a negative potential difference whose absolute value of the voltage applied in the odd frame is the same and the sign is changed have. At this time, since the first optical path changing cell 300a has a half-wave retarding function, the light passing through the first optical path changing cell 300a becomes a right circularly polarized state. The right circularly polarized light is deflected upward and downward by the second optical path changing cell 300b. That is, in the coordinate system of FIG. 6, the light beam is refracted at an angle? That is, light having stereoscopic image information traveling in the Z direction is deflected toward a desired position on the X axis and the Y axis. In particular, the second optical path changing cell 300b can form a prism pattern having a lower inclined plane by driving the liquid crystal using a positive potential difference whose absolute value of the voltage applied in the odd frame is the same and the sign is changed have.

As described above, in the case of the odd frame, the right circularly polarized light is deflected by using the slope prism pattern. In the even frame, the left circularly polarized light is deflected by using the right slope prism pattern. The light emitted from the even-numbered frame can be supplied to the same position.

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 present invention should not be limited to the details described in the detailed description, but should be defined by the claims.

10: computer 20: SLM (spatial light modulator)
30: laser light source 40: expander
50: Lens 80: Output image
90: Reference light
100: Hologram display panel 300: Light path conversion cell
300a: first light path conversion cell 300b: second light path conversion cell
500: display panel driver 600: light path conversion cell driver
800: control unit 900: detection camera
AQP: Active quarter wave retarder BLU: Backlight unit

Claims (8)

An active quadruple wavelength delay plate for converting the linearly polarized light into either one of the first circularly polarized light and the second circularly polarized light; And
And a first optical path changing cell forming one of a first prism pattern and a second prism pattern.
The method according to claim 1,
During a period in which the active quadruple wavelength delay plate converts the linearly polarized light to the first circular polarization state, the first optical path changing cell forms the first prism pattern;
Wherein the first optical path changing cell forms the second prism pattern while the active quarter wave retarder changes the linearly polarized light to the second circularly polarized light state.
3. The method of claim 2,
The first circularly polarized light is left-handed circularly polarized light, the second circularly polarized light is right-handed circularly polarized light, and the first prismatic pattern deflects the left-circularly polarized light in a horizontal direction by a refraction angle?
And the second prism pattern deflects the right-handed polarized light in the horizontal direction by the refraction angle &amp;thetas;.
The method according to claim 1,
Wherein the first light path conversion cell comprises HAN mode liquid crystal molecules,
Wherein the voltage for forming the first prism pattern is the same as the absolute value of the voltage for forming the second prism pattern, and the sign is opposite.
The method according to claim 1,
And a second optical path changing cell forming one of a third prism pattern and a fourth prism pattern.
6. The method of claim 5,
The second optical path changing cell forms the third prism pattern while the active quarter wave retarder changes the linearly polarized light to the first circularly polarized light state;
Wherein the second optical path changing cell forms the fourth prism pattern during a period in which the active quarter wave retarder changes the linearly polarized light to the second circularly polarized light state.
The method according to claim 6,
Wherein the first circularly polarized light is left-handed circularly polarized light, the second circularly polarized light is right-handed circularly polarized light, and the third prismatic pattern deflects the left-circularly polarized light vertically by a refraction angle?
And the second prism pattern deflects the right-handed polarized light in the vertical direction by the refraction angle?.
6. The method of claim 5,
Wherein the second optical path change cell comprises HAN mode liquid crystal molecules,
Wherein the voltage for forming the third prism pattern is the same as the absolute value of the voltage for forming the fourth prism pattern, and the sign is opposite.

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