KR101387830B1 - Sub pannel and three dimensinaol image display having the same - Google Patents

Abstract

The present invention provides a sub-panel that provides a stereoscopic image to an observer wearing polarized glasses by converting polarization information of the first image and the second image alternately output from the main panel, wherein the first electrode layer and the second electrode are spaced apart from each other. Disclosed is a sub panel including an electrode layer, a liquid crystal layer filled between the first electrode layer and a second electrode layer, and a phase delay film disposed on one surface of the first electrode layer or the second electrode layer, and a stereoscopic image display device including the same. do.

Description

SUB PANNEL AND THREE DIMENSINAOL IMAGE DISPLAY HAVING THE SAME}

The present invention relates to a stereoscopic image display device.

2. Description of the Related Art [0002] There has been active research on a stereoscopic image display device that converts a two-dimensional image formed on a display device into a three-dimensional image in accordance with recent technological advances.

In general, three-dimensional stereoscopic images are generally produced using the principle of binocular disparity through two eyes of a human being.

Since the two eyes of the human being are separated by a certain distance, the images observed from different angles with each eye are input to the brain, which enables the observer to perceive the sense of space by recognizing the three-dimensional feeling.

Among the principles of the 3D image, polarizer glasses are used to convert the polarization of the first image and the second image to be transmitted by including a subpanel on the display device for transmitting the first image and the second image. Then, the light is incident on the polarized glasses to realize a 3D image.

Referring to FIG. 1A, the conventional subpanel includes a liquid crystal layer 30 between the first electrode layer 10 and the second electrode layer 20. Since the liquid crystal of the liquid crystal layer 30 is aligned in parallel with the first electrode layer 10 and the second electrode layer 20, the polarized light passing through the subpanel feels birefringence of λ / 2 retardation. Therefore, it is rotated perpendicular to the polarization direction before passing through the sub-panel and is incident on the right eye of the polarizing glasses.

Subsequently, when a voltage is applied to the first electrode layer 10 and the second electrode layer 20 as shown in FIG. 1B, a vertical electric field is formed so that the liquid crystal 31 may have the first electrode layer 10 and the second electrode layer 20. Aligned vertically). Therefore, since the incident polarization does not feel birefringence, it is incident on the left eye of the polarizing glasses without changing the polarization.

However, the liquid crystals 32 disposed close to the first electrode layer 10 and the second electrode layer 20 are not vertically aligned due to the coupling energy of the alignment layer formed on the electrode layer. There is.

Therefore, the incident polarization is delayed in phase due to this residual retardation, so that some of the polarization glasses are not incident on the right eye (reduction of white in the right eye) or incident on the left eye of the polarizing glasses (dark reduction in the left eye). There is a problem in that the quality of a stereoscopic image is deteriorated.

Therefore, the contrast ratio of the left and / or right eyes is extremely reduced due to residual retardation, resulting in an asymmetric contrast ratio. There is a growing problem.

The present invention provides a subpanel for a stereoscopic display device that can realize a high contrast ratio by canceling the remaining retardation of the subpanel.

The present invention also provides a sub-panel for a stereoscopic display device capable of uniformly converting light in a visible light region into circularly polarized light.

The sub-panel according to the present invention is a sub-panel which provides a stereoscopic image to an observer wearing polarized glasses by converting polarization information of the first image and the second image, which are alternately output from the main panel, and spaced apart from each other. A first electrode layer and a second electrode layer; A liquid crystal layer filled between the first electrode layer and the second electrode layer; And a phase delay film disposed on one surface of the first electrode layer or the second electrode layer.

In the sub-panel according to the present invention, the slow axis of the retardation film has a 90 ° or −90 ° with respect to the rubbing direction of the sub-panel, and the retardation value is formed from 147.5 nm to 177.5 nm.

In the sub-panel according to the present invention, the liquid crystal layer includes an OCB (Optically Compensated Birefringence) or ECB (Electrically Controlled Birefringence) mode liquid crystal.

In the sub-panel according to the present invention, the apparatus further includes a power supply unit configured to apply a voltage to the first electrode layer and the second electrode layer to form a vertical electric field in the liquid crystal layer.

In the sub-panel according to the present invention, the phase delay film includes a first phase delay film and a second phase delay film.

In the sub-panel according to the present invention, the rubbing direction of the sub-panel is 45 ° based on the transmission axis of the polarizing plate formed on the upper part of the main panel, and the slow axis of the first phase delay film is disposed on the upper part of the main panel. 136 ° to 145 ° based on the transmission axis of the formed polarizing plate, and the slow axis of the second phase delay film is formed to be 54 ° to 133 °.

In the sub-panel according to the present invention, the phase delay value of the first phase delay film is 145 to 200 nm, and the phase delay value of the second phase delay film is 6 to 66 nm.

According to the present invention, the residual retardation generated by the coupling energy of the liquid crystal and the alignment layer is canceled to significantly increase the contrast ratio, thereby preventing the 3D crosstalk phenomenon and providing an excellent stereoscopic image. In addition, the stereoscopic feeling may be improved by uniformly converting light in the visible light region into circularly polarized light.

1 is a schematic diagram of a sub-panel according to the related art,
2 is a schematic diagram of a stereoscopic image display device according to an embodiment of the present invention;
3 is a schematic diagram of a sub-panel according to an embodiment of the present invention;
Figure 4 is a graph measuring the contrast ratio of the left eye image according to the phase delay value of the phase delay film,
5 is a graph measuring the contrast ratio of the right eye image according to the phase delay value of the phase delay film.
6 is a schematic view of a sub panel according to another embodiment of the present invention;
FIG. 7 is a photograph showing a state in which light leakage of light passing through a sub-panel with a conventional phase delay film is generated.
8 is a photograph showing a state in which light leakage of light passing through a sub-panel according to the present invention is suppressed to increase the contrast ratio,
9 and 10 are spherical angular spherical surface showing a state in which blue light, green light, and red light are converted into circularly polarized light when the sub panel is turned on;
FIG. 11 is a spherical angular spherical surface showing a state in which blue light, green light, and red light are converted into circularly polarized light when the sub-panel is switched off.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present invention, the terms "comprising" or "having ", and the like, specify that the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the drawings, wherein like or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

2 is a schematic diagram of a stereoscopic image display device according to an embodiment of the present invention.

Referring to FIG. 2, a stereoscopic image display apparatus according to an exemplary embodiment of the present invention includes a main panel 200 that alternately displays a first image and a second image, and the first panel displayed on the main panel 200. A sub-panel 300 for converting the image into the first circularly polarized light and converting the second image into the second circularly polarized light, and a polarizing glasses 400 to which the first and second circularly polarized light are incident, respectively. .

In the present embodiment, a liquid crystal display (LCD) is illustrated as a display device, but the present invention is not limited thereto, but the plasma display device (PDP) and the organic light emitting display device (OLED) for alternately outputting the first image and the second image. The display panel may be implemented as a panel of various display devices.

The liquid crystal display is divided into a backlight unit 100, which serves as a light source, and a main panel 200, which forms an image by controlling light provided from the backlight unit 100.

Since the general configuration of the backlight unit 100 will be apparent to those skilled in the art, further detailed descriptions thereof will be omitted, and in addition to the side type backlight shown in FIG.

Specifically, as shown in FIG. 2, the main panel 200 includes a main liquid crystal layer 230 between the TFT substrate 210 and the color filter substrate 220, and the TFT panel 210 and the color filter substrate 220. The first polarizing plate 240 and the second polarizing plate 250 are attached to the outer surface, respectively. In this case, the polarization axes of the first polarizing plate 240 and the second polarizing plate 250 are formed to be orthogonal to each other, and are configured to control light according to the direction of the liquid crystal. In this case, both the first image and the second image passing through the main panel 200 are linearly polarized light.

The main panel 200 alternately displays a first image to be incident to the observer's left eye and a second image to be incident to the right eye in order to implement a stereoscopic image, and the first image and the second image are arranged in a predetermined order and time. Are displayed alternately.

The sub panel 300 changes the polarization information of the first image and the second image passing through the main panel 200. That is, the first image and the second image are converted into left circularly polarized light and right circularly polarized light, respectively, and provided to the left eye lens 410 and the right eye lens 420 of the polarizing glasses 400 to provide a stereoscopic image to the viewer. At this time, the left circular circular polarizing plate is attached to the left eye lens 410 of the polarizing glasses 400, and the right circular circular polarizing plate is attached to the right eye lens 420.

3 is a schematic diagram of a sub-panel according to an embodiment of the present invention, Figure 4 is a graph measuring the contrast ratio of the left eye image according to the phase delay value of the phase delay film, Figure 5 is a phase delay value of the phase delay film It is a graph measuring contrast ratio of right eye image.

Referring to FIG. 3, in the sub-panel 300, the first electrode layer 310 and the second electrode layer 320 are spaced at predetermined intervals, and the liquid crystal layer 330 is filled therebetween. The thickness of the liquid crystal layer 330 is formed to a thickness that can delay the phase of incident linearly polarized light by 1/2 wavelength.

Although not shown, an alignment layer is formed on a surface where the first electrode layer 310 and the second electrode layer 320 face each other, and includes a power source for applying a voltage to the first electrode layer 310 and the second electrode layer 320. . Therefore, when a voltage is applied to the first electrode layer 310 and the second electrode layer 320, a vertical electric field is formed in the liquid crystal layer 330 to vertically arrange the liquid crystals.

The liquid crystal L of the liquid crystal layer is aligned along the rubbing direction of the alignment film. In the present invention, the liquid crystal L is horizontally aligned with the first electrode layer 310 and the second electrode layer 320 by the alignment layer. In more detail, the liquid crystal layer may be implemented in an OCB (Optically Compensated Birefringence) or an ECB (Electrically Controlled Birefringence) mode.

When the liquid crystals (L) are arranged horizontally with the electrode layer, compared to the general twisted nematic (TN) or super twisted nematic (STN) mode, the alignment characteristics of the liquid crystals (L) are uniformly arranged in one direction without disturbing the wavelength dispersion characteristics, It is advantageous in electro-optical properties such as contrast ratio.

When the first image is emitted from the main panel 200, a voltage is applied to the first electrode layer 310 and the second electrode layer 330 of the subpanel so that the liquid crystal layer 330 is switched on at high speed by a vertical electric field. Therefore, the first image is transmitted as it is without phase delay. Thereafter, the first image is converted into right circularly polarized light while passing through the phase delay film 340 and is incident on the right eye lens of the polarizing glasses.

When the second image is emitted from the main panel 200, since the vertical electric field is removed and the liquid crystal is restored to its original position, the second image is delayed in phase by λ / 2 wavelengths. The second image whose phase is delayed is converted into left circularly polarized light while passing through the phase delay film 340 and is incident on the left eye lens.

In this case, the phase delay film 340 may be selected as a 1/4 wavelength phase delay film in order to convert the first image and the second image which is linearly polarized light into circularly polarized light. However, as described above, since some residual retardation exists due to the coupling energy generated between the liquid crystal and the alignment layer, a 1/4 wavelength phase delay film having a phase delay value of 130 to 140 nm is disposed on the subpanel. In this case, the first image and / or the second image are not properly converted to circular polarized light.

Accordingly, the first image and / or the second image are converted into elliptical polarization, and the left and right eyes of the polarized glasses enter the mixed image of the first and second images, respectively, and the contrast ratio of the left and / or right eyes is greatly reduced. Done.

The contrast ratio (CR) is defined as the ratio of white when left circularly polarized light is incident to the left eye and dark when right circularly polarized light is incident, or dark when white and left circularly polarized light are incident when right circularly polarized light is incident to the right eye. It may be, and can be defined by the following [Equation 1].

Where λ is the wavelength and P and D are the photopia response and illuminant spectral distribution of the human eye, respectively.

Referring to [Table 1] below, theoretically, if all of the first image passed through the subpanel is converted to right circularly polarized light and the second image is converted to left circularly polarized light, the left circularly polarized light is incident on the left eye of the polarized glasses. Since the white value increases and the right circular polarization is not incident at all on the left eye, the dark value increases and the contrast ratio increases as a whole. However, in reality, part of the first image and the second image becomes an elliptical polarization, so that a part of the left circular polarization and a part of the right circular polarization are incident to the left or right eye, and thus the contrast ratio is significantly lowered.

Left eye (only left polarized light) Right eye (through circular polarization) Ideal On Switching
(0 retardation) Perfect dark because circular arcs cannot pass All polarized light passes through, so perfect white Ideal Off Switching
(λ / 2 retardation) All white circularly polarized light passes through, so perfect white Left circular polarization is not good, so perfect dark Actual On Switching
(residual retardation) Right circularly polarized light enters some left eye, resulting in low dark value (a significant decrease in contrast ratio) Reduced white since only part of the right polarized light passes

Referring to FIG. 4, in the case of a quarter-wave retardation film having a phase delay value of 137.5 nm, even when a high voltage of about 10 V or more is applied, the contrast ratio of the left eye image is low as about 47: 1. This is because part of the left eye image is converted into elliptical polarization by residual retardation. When the contrast ratio of one image is less than 200: 1, even if the contrast ratio of the other image exceeds 200: 1, it causes fatigue to the eyes of the viewer.

In addition, in the case of the 187.5 nm phase delay film, it has a contrast ratio of 15000: 1 only in the voltage range of about 4V, but it can be seen that the contrast ratio is dramatically lowered at higher voltages.

On the other hand, when the phase delay value is 147.5 nm to 177.5 nm, the contrast ratio has a contrast ratio of 200: 1 or more in the general driving voltage range (about 2 to 20V). It can be seen that when the phase delay value of the phase delay film is adjusted from 147.5 nm to 177.5 nm, the residual retardation generated by the liquid crystal layer may be offset. Therefore, the phase delay value of the phase delay film may have a phase delay value within 147.5 nm to 177.5 nm.

Referring to FIG. 5, it can be seen that the right eye image has a contrast ratio characteristic of 200: 1 or more in most phase delay films of 137.5 nm to 197.5 nm.

Table 2 below summarizes the contrast ratios according to the phase delay values of the left eye image and the right eye image. In Table 2, Good is a case where the contrast ratio is 200: 1 or more, and Bad is a case where the contrast ratio is 200: 1 or less.

Phase delay value Left eye CR Right eye CR 137.5 nm Bad Good 147.5 nm Good Good 157.5 nm Good Good 177.5 nm Good Good 187.5 nm Bad Good 197.5 nm Bad Good

Referring to Table 2, the right eye image generally shows a good contrast ratio regardless of the phase delay value of the phase delay film, but the left eye image has a phase delay value of 147.5 nm to 177.5 nm, indicating that the contrast ratio is improved. .

This is because the residual retardation occurs when the liquid crystal of the sub-panel is vertically switched on to convert the polarization of the left eye image. Therefore, in order to offset the residual retardation, the phase delay layer preferably has a phase delay value of 147.5 nm to 177.5 nm. In this case, both the first image and the second image are effectively converted into circularly polarized light by the phase delay film, and the contrast ratio is improved, thereby significantly reducing the 3D crosstalk phenomenon.

6 is a schematic diagram of a sub-panel according to another embodiment of the present invention. Referring to FIG. 6, in the sub-panel according to the present invention, the first electrode layer 310 and the second electrode layer 320 are spaced at predetermined intervals, and the liquid crystal layer 330 is filled therebetween. The first phase delay film 341 and the second phase delay film 342 are sequentially disposed on the second electrode layer 320. In this case, the first phase delay film and the second phase delay film may be disposed under the first electrode layer 310.

Table 3 below is a table measuring the contrast ratio of the left and right eyes by adjusting the slow axis and the phase delay values of the two phase delay films. In the following Table 3, when the contrast ratio is 200: 1 or less, it is expressed as NG.

1st phase delay film 2nd phase delay film result Slow axis (°) Phase delay value (nm) Slow axis (°) Phase delay value (nm) Comparative Example 1 137 140 107 5 NG Comparative Example 2 138 160 52 10 NG Comparative Example 3 150 150 97 25 NG Comparative Example 4 140 115 129 67 NG Example 1 140 115 129 50 OK Example 2 137 160 117 10 OK Example 3 138 160 80 10 OK Example 4 137 155 118 10 OK Example 5 137 150 107 6 OK

Referring to [Table 3], in the case of Comparative Example 1, the contrast ratio of the left eye image was measured to be 97: 1, and the contrast ratio was significantly decreased. In Comparative Example 2, the contrast ratio of the left eye image was 192: 1. It was determined to be lower than 200: 1.

In contrast, in Example 5, the contrast ratio of the left eye image was measured to be 572: 1, and the contrast ratio of the right eye image was measured to be 1532: 1, so that the contrast ratio of the left eye image was 1317. The contrast ratio of the right eye image was measured as 832: 1 and the contrast ratio of the left and right eyes was found to have excellent contrast ratio of more than 500: 1.

Based on the results of Table 3, based on the transmission axis (0 °) of the upper polarizing plate 240 of the main panel 200, the first phase delay film 341 is the ground of the first phase delay film 341 Slow axis is 136 ° to 145 °, phase delay value is 145 to 200 nm, Slow axis of second phase delay film 342 is 54 ° to 133 ° and phase delay value is 6 to In the case of 66 nm, it can be seen that both the left eye image and the right eye image may have a contrast ratio of 500: 1 or more.

FIG. 7 is a photograph showing a state in which light leakage of light passing through a sub-panel with a conventional phase delay film is generated, and FIG. 8 is a light leakage of light passing through a sub-panel according to the present invention. This picture shows the rising state.

Referring to FIG. 7, the white value of the light passing through the sub-panel with the conventional 137.5 nm phase delay film is generally good, but it is understood that light leakage occurs because it is not completely converted into circular polarization due to residual retardation during ON switching. Can be. Due to this light leakage, the dark value is lowered and the overall contrast ratio is lowered.

On the other hand, referring to Figure 8, when the two phase delay film according to this embodiment is attached, it can be seen that the conversion of the circularly polarized light is relatively high, the dark value is increased. Therefore, the contrast ratio rises.

9 and 10 are spherical angular spherical surfaces showing a state in which blue light (450 nm), green light (550 nm), and red light (650 nm) are converted into circularly polarized light during incident polarization when the sub-panel is switched on, and FIG. Is a spherical angular spherical surface showing the state in which blue light, green light, and red light are converted to circularly polarized light upon switching OFF.

Referring to FIGS. 9 and 10, when the ON panel of the present invention is switched on (when a vertical electric field is formed in the liquid crystal), blue light (450 nm), green light (550 nm), and red light (650 nm) are all right (right) in a Poohcare sphere. It can be seen that it is adjacent to the S3 point indicating the left circular arc. As a result, it can be seen that all light in the entire visible light region is converted into circularly polarized light while passing through the sub-panel.

Further, as shown in FIG. 11, when the sub-panel of the present invention is switched off (when no vertical electric field is formed in the liquid crystal), blue light (450 nm), green light (550 nm), and red light (650 nm) are all left (right) in a Poang Kare sphere. It can be seen that it is converted into circularly polarized light adjacent to the point -S3 representing circularly polarized light.

Therefore, it can be seen that the light of each wavelength band is collected at the S3 or -S3 position and converted into left circularly polarized light and right circularly polarized light, respectively. Can be.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

100: backlight unit 200: main panel
300: sub panel 310: first electrode layer
320: second electrode layer 330: third electrode layer
340: phase delay film 341: first phase delay film
342: second phase delay film

Claims (13)

In the sub-panel for converting the polarization information of the first image and the second image output alternately from the main panel to provide a stereoscopic image to the observer wearing a polarized glasses,
A first electrode layer and a second electrode layer spaced apart from each other;
A liquid crystal layer filled between the first electrode layer and the second electrode layer; And
And a phase delay film disposed on one surface of the first electrode layer or the second electrode layer.
The phase delay film includes a first phase delay film and a second phase delay film,
The slow axis of the first phase delay film is 136 ° to 145 ° based on the transmission axis of the polarizing plate formed on the main panel, and the slow axis of the second phase delay film is 54 ° to Sub-panel of 133 °. The sub-panel of claim 1, wherein a contrast ratio between the first image and the second image in which polarization information is converted through the sub-panel is 200: 1 or more. The sub-panel of claim 2, wherein the phase delay value of the phase delay film is 147.5 nm to 177.5 nm. The sub-panel of claim 1, wherein the liquid crystal layer comprises liquid crystals of an OCB (Optically Compensated Birefringence) or an ECB (Electrically Controlled Birefringence) mode. The sub-panel of claim 1, further comprising a power supply unit configured to apply a voltage to the first electrode layer and the second electrode layer to form a vertical electric field in the liquid crystal layer. delete delete The sub-panel of claim 1, wherein the phase delay value of the first phase delay film is 145 to 200 nm, and the phase delay value of the second phase delay film is 6 to 66 nm. A main panel for alternately displaying a first image and a second image;
A sub-panel disposed on the main panel to change polarization information of the first image and the second image; And
And polarizing glasses in which the first and second images are incident on the left and right lens.
The sub-panel,
A first electrode layer and a second electrode layer spaced apart from each other;
A liquid crystal layer filled between the first electrode layer and the second electrode layer; And
And a phase delay film disposed on one surface of the first electrode layer or the second electrode layer.
The phase delay film includes a first phase delay film and a second phase delay film,
The slow axis of the first phase delay film is 136 ° to 145 ° based on the transmission axis of the polarizing plate formed on the main panel, and the slow axis of the second phase delay film is 54 ° to 133 ° stereoscopic image display. delete delete The stereoscopic image display device of claim 9, wherein the phase delay value of the first phase delay film is 145 to 200 nm, and the phase delay value of the second phase delay film is 6 to 66 nm. The stereoscopic image display device of claim 9, wherein a contrast ratio of the first image and the second image, through which the polarization information is converted through the sub-panel, is 200: 1 or more.

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