KR20070046248A - Liquid crystal display device capable of changing low viewing angle mode - Google Patents

Abstract

The present invention relates to a liquid crystal display device capable of switching the narrow viewing angle mode, and the liquid crystal display device capable of switching the narrow viewing angle mode according to the present invention includes a backlight unit; A switching lens sheet for selectively changing a traveling path of the light; And a liquid crystal display panel for displaying an image on the screen through light traveling through the switching lens sheet, wherein the narrow viewing angle mode is switched as necessary by using a switching lens instead of the prism sheet. It is possible.

Switching lens sheet, prism sheet, light guide plate

Description

Liquid crystal display device that can switch narrow viewing angle mode {LIQUID CRYSTAL DISPLAY DEVICE CAPABLE OF CHANGING LOW VIEWING ANGLE MODE}

1 is an exploded cross-sectional view of a backlight unit and a liquid crystal display panel according to the prior art, a schematic view for explaining the path of light emitted from the light guide plate.

FIG. 2 is a schematic view illustrating a form in which a path of light path changes when light emitted from a light guide plate passes through each film in the liquid crystal display device according to the related art. FIG.

3A is a state diagram in which a switching lens sheet is disposed between a backlight unit and a liquid crystal display panel according to an exemplary embodiment of the present invention. When the switching lens sheet is operated, light emitted from the light guide plate passes through the switching lens sheet. Schematic showing change,

3B is a state diagram in which a switching lens sheet is disposed between a backlight unit and a liquid crystal display panel according to the present invention. When the switching lens sheet is not operated, light emitted from the light guide plate passes through the switching lens sheet and changes in path. Indicative schematic.

4 is an exploded cross-sectional view of a backlight unit and a liquid crystal display panel according to another embodiment of the present invention, in which a switching lens sheet is disposed on the liquid crystal display panel.

5A is a cross-sectional view of a switching lens sheet structure applied to a liquid crystal display device composed of a backlight unit and a liquid crystal display panel according to the present invention, and FIG. 5A is a view in which no voltage is applied to the switching lens sheet (narrow view angle mode).

Figure 5a is a cross-sectional view of a switching lens sheet structure applied to a liquid crystal display device composed of a backlight unit and a liquid crystal display panel according to the present invention, Figure 5b is a voltage applied to the switching lens sheet (wide viewing angle mode).

6A is a cross-sectional view of a switching lens sheet structure applied to a liquid crystal display device including a backlight unit and a liquid crystal display panel according to the present invention. FIG. 6A illustrates a liquid lens method using an electronic-wetting phenomenon. Schematic diagram showing the path change of light when not applied.

6B is a cross-sectional view of a switching lens sheet structure applied to a liquid crystal display device including a backlight unit and a liquid crystal display panel according to the present invention. FIG. 6B is a view illustrating a liquid lens method using an electronic-wetting phenomenon. Schematic diagram showing the path change of light when applied.

********* Description of the symbols for the main parts of the drawings **********

100: backlight unit 111: light guide plate

113: lamp assembly 115: lamp

117: lamp housing 119: reflector

121: diffusion sheet 123: switching lens sheet

125: protective sheet 130: liquid crystal display panel

141: light path

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of narrow viewing angle mode switching by using a switching lens sheet instead of a conventional prism sheet.

In general, a liquid crystal display device is a display device in which data signals according to image information are individually supplied to pixels arranged in a matrix form, and thus a desired image is displayed by adjusting light transmittance of the pixels. .

The liquid crystal display includes a liquid crystal display panel in which pixels are arranged in a matrix, and a driving circuit unit for driving the pixels.

Here, the liquid crystal display panel is a thin film transistor array (TFT array) substrate and a color filter substrate bonded to each other while maintaining a constant cell gap, the color filter substrate and TFT array It consists of a liquid crystal layer filled with a plurality of liquid crystal in the spaced space of the substrate.

In addition, a common electrode and a pixel electrode are formed in the liquid crystal display panel where the TFT array substrate and the color filter substrate are bonded to apply an electric field to the liquid crystal layer.

Therefore, when the voltage of the data signal applied to the pixel electrode is controlled while the voltage is applied to the common electrode, the liquid crystal of the liquid crystal layer rotates by dielectric anisotropy according to the electric field between the common electrode and the pixel electrode. Characters or images are displayed by transmitting or blocking light for each pixel.

Since the liquid crystal display does not emit light by itself and has a characteristic of displaying an image by adjusting the transmittance of light supplied from the outside, an additional means for irradiating light to the display panel, that is, a backlight assembly is required.

The backlight assembly is divided into a direct method in which a light source is disposed on a rear surface of the display panel and an edge method in which the light source is disposed on one side or both sides of the display panel. The edge type liquid crystal display device is a light source for supplying light to the liquid crystal panel, and a lamp assembly is formed on the side of the liquid crystal panel. In addition, the light supplied from the lamp assembly is guided to the liquid crystal panel by a light guide plate formed under the liquid crystal panel.

In this regard, the backlight unit and the liquid crystal display panel of the edge type liquid crystal display will be described with reference to FIGS. 1 and 2 as follows.

1 is an exploded cross-sectional view of a backlight unit and a liquid crystal display panel according to the prior art, a schematic view for explaining the path of light emitted from the light guide plate.

FIG. 2 is a schematic view of a liquid crystal display according to the related art, in which a light path traveling direction of the light emitted from the light guide plate is changed when passing through each film.

Referring to FIG. 1, a general edge type liquid crystal display device includes a backlight unit 10 for supplying a light source and a liquid crystal display panel 30 for displaying an image by adjusting a transmittance of light supplied from the backlight unit 10. It consists of.

Here, the backlight unit 10 includes a light guide plate 11 disposed on a side surface of the backlight unit 10 and a lamp assembly 13 disposed on a side surface of the light guide plate 11.

The lamp assembly 13 includes a lamp housing 17 as a light emitter and a lamp housing 17 for concentrating light generated from the lamp 15 to the light guide plate 11.

In addition, first and second prisms disposed on the light guide plate 11 to be orthogonal to the diffusion sheet 21 so as to more efficiently supply the light traveling from the light guide plate 11 to the liquid crystal display panel 30. The sheets 23 and 25 and the protective sheet 27 are stacked, and the liquid crystal display panel 30 is disposed on the protective sheet 27.

A reflective sheet 19 is provided below the light guide plate 11 to reflect the light 41 incident on the light guide plate 11 from the lamp 15 toward the liquid crystal display panel 30.

 The light emitted from the lamp 15 disposed in the backlight unit 10 configured as described above is incident at a predetermined angle to the side of the light guide plate 11 and is emitted to the front through the light guide plate 11.

Referring to FIG. 2, most of the light emitted from the light guide plate 11 is emitted laterally by an angle of about 60 to 80 °, and the emitted light is diffused by the plate 21 and the first and second prism sheets. The luminance is improved by being collected in the direction of the front surface, that is, the liquid crystal display panel, through the 23) and (25). In this case, the first and second prism sheets 23 and 25 collect light, that is, condensing light. Here, reference numeral 43 denotes a light traveling range.

As described above, according to the liquid crystal display device according to the prior art, the light cannot be spread from all directions, so that the viewing angle of viewing is reduced.

In addition, when the prism sheet is used, the luminance is increased but the viewing angle is reduced. On the contrary, when the freeze sheet is not used, the viewing angle increases, but the luminance decreases.

Therefore, in a product where the viewing angle is as important as luminance, a separate luminance increasing film may be used instead of the prism sheet.

Moreover, in recent years, a technology for adjusting the viewing angle using a liquid crystal panel and various compensation films has been proposed to reduce the viewing angle so that only one worker can view in an area where information security is required.

However, the film that reduces the viewing angle, that is, the prism sheet, is not switchable, and since the liquid crystal panel and the compensation film need to be added, the price increase factor is high and the luminance is likely to be lowered.

Accordingly, an object of the present invention is to provide a liquid crystal display device capable of narrowing the viewing angle mode as needed by using a switching lens instead of a prism sheet.

Liquid crystal display device according to the present invention for achieving the above object, the backlight unit for supplying a light source; A switching lens sheet for selectively changing a traveling path of the light; And a liquid crystal display panel which displays an image on the screen through the light traveling through the switching lens sheet.

In addition, during operation of the switching lens sheet, a path of light passing through the switching lens sheet travels in the vertical direction.

The backlight unit includes a light guide plate, and a diffusion sheet is provided between the light guide plate and the switching lens sheet.

In addition, a protective sheet is provided between the switching lens sheet and the liquid crystal display panel.

The switching lens sheet is positioned between the backlight unit and the liquid crystal display panel or on the liquid crystal display panel.

In addition, the switching lens sheet includes a switching lens using a liquid crystal or a liquid lens using an electron-wetting phenomenon.

The switching lens using the liquid crystal includes a lens-type substrate having a plurality of grooves formed on a glass substrate and a lower surface thereof, a first transparent electrode layer formed on the glass substrate, a first alignment layer formed on the first transparent electrode layer, And a second alignment layer formed on a lower surface including the groove of the lenticular substrate, a liquid crystal layer injected into a space formed by bonding the glass substrate and the lens substrate, and a second transparent electrode layer formed on the lens substrate. It is characterized by.

Further, a narrow viewing angle mode is formed when a voltage is applied to the switching lens using the liquid crystal, and a wide viewing angle mode is formed when a voltage is not applied to the switching lens using the liquid crystal.

In addition, the liquid lens using the electron-wetting phenomenon may include a first glass substrate, a second glass substrate having a hydrophobic thin film formed on a lower surface thereof, a partition provided between the first glass substrate and the second glass substrate, and the second glass substrate. A hydrophobic fluid layer and a conductive fluid layer filled in a space formed by the first glass substrate and the second glass substrate, the hydrophobic fluid layer and the conductive fluid layer, an insulating layer interposed between the partition wall and the second glass substrate, and the first layer. And an electrode provided on each of the first and second glass substrates.

In addition, a narrow viewing angle mode is formed when a voltage is applied to the liquid lens using the electron-wetting phenomenon, and a wide viewing angle mode is formed when a voltage is not applied to the liquid lens.

Hereinafter, a liquid crystal display capable of narrow viewing angle mode switching according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3A is a state diagram in which a switching lens sheet is disposed between a backlight unit and a liquid crystal display panel according to an embodiment of the present invention. When the switching lens sheet is operated, light emitted from the light guide plate passes through the switching lens sheet. It is a schematic diagram showing what is changed.

3b is a state diagram in which a switching lens sheet is disposed between a backlight unit and a liquid crystal display panel according to the present invention. In the case where the switching lens sheet is not operated, the path of the light emitted from the light guide plate passes through the switching lens sheet. It is a schematic diagram showing.

4 is an exploded cross-sectional view of a backlight unit and a liquid crystal display panel according to another exemplary embodiment, in which a switching lens sheet is disposed on the liquid crystal display panel.

5A and 5B are cross-sectional views of a switching lens sheet structure applied to a liquid crystal display device including a backlight unit and a liquid crystal display panel according to the present invention, and FIG. 5A is a case where no voltage is applied to the switching lens sheet (narrow view angle mode). 5B illustrates a case where a voltage is applied to the switching lens sheet (wide viewing angle mode).

6A and 6B are cross-sectional views of a switching lens sheet structure applied to a liquid crystal display device including a backlight unit and a liquid crystal display panel according to the present invention. FIG. 6A illustrates a liquid lens method using an electronic-wetting phenomenon. FIG. 6B is a schematic diagram illustrating a path change of light that appears when no voltage is applied to a liquid lens, and FIG. 6B is a schematic diagram illustrating a path change of light that appears when a voltage is applied to a liquid lens.

Referring to FIG. 3A, an edge type liquid crystal display device according to an exemplary embodiment of the present invention controls a backlight unit 100 for supplying a light source and a liquid crystal for displaying an image by controlling a transmittance of light supplied from the backlight unit 100. The display panel 130 is configured.

The backlight unit 100 includes a light guide plate 111 to which light is incident, and a lamp assembly 113 disposed on a side surface of the light guide plate 111.

The lamp assembly 113 may include a lamp 115 as a light emitter and a lamp housing 117 for concentrating light generated from the lamp 115 to the light guide plate 111.

In addition, the diffusion sheet 121, the switching lens sheet (123) and the protective sheet on the upper portion of the light guide plate 111 in order to more efficiently supply the light traveling from the light guide plate 111 to the liquid crystal panel. The liquid crystal display panel 130 is disposed on the protective sheet 125.

Here, the switching lens sheet 123 is not related to any shape, but in order to collect all the light in the vertical and horizontal directions, rather than a cylindrical lens shape, the planar shape viewed from above is a polygon or circular micro lens array such as hexagon. Sheet form is preferred.

A reflective sheet 119 is provided below the light guide plate 111 to reflect light incident from the lamp 115 into the light guide plate 111 toward the liquid crystal display panel 130.

The light emitted from the lamp 115 disposed in the backlight unit 100 configured as described above is incident at a predetermined angle to the side of the light guide plate 111 and is emitted to the front surface through the light guide plate 111.

As such, most of the light emitted from the light guide plate 111 is emitted in the lateral direction, but instead of the existing prism sheet, the light path 141 is narrowly adjusted toward the center in the vertical direction while passing through the switching lens sheet 123. A narrow viewing angle is realized through the display panel 130.

As shown in FIG. 3A, when the switching lens sheet 123 is used instead of the conventional prism sheet, light may be condensed to improve the same effect as that of the conventional prism sheet, that is, brightness. In particular, since the light cannot be spread in all directions by the switching lens sheet 123, the viewing angle of view is reduced.

In addition, by using a switching lens instead of a conventional prism sheet, the lens operation can be turned on / off at any time by an electrical signal.

Therefore, as shown in FIG. 3A, when the switching lens sheet 123 is operated, the viewing lens viewing angle is narrowed by the switching lens sheet 123 properly concentrating light and emitting the light vertically to the liquid crystal display panel 130.

On the other hand, as shown in FIG. 3B, when the operation of the switching lens sheet 123 is stopped, the viewing angle is widened because light is emitted from the liquid crystal display panel 130 in all directions.

Meanwhile, as another embodiment according to the present invention, the position of the switching lens sheet is not disposed at the same position as that of the existing prism sheet as shown in FIGS. 3A and 3B, and as shown in FIG. It can also be placed in.

In addition, as an embodiment of the switching lens sheet applied to the liquid crystal display device capable of switching the narrow viewing angle mode according to the present invention, a switchable lens using a liquid crystal shown in FIGS. 5A and 5B, or FIG. 6A And a liquid lens using the electro-wetting phenomenon shown in FIG. 6B.

As an embodiment of the switching lens according to the present invention, the light path through the switching lens using the liquid crystal shown in Figures 5a and 5b will be described as follows.

5A and 5B are cross-sectional views of a switching lens sheet structure applied to a liquid crystal display device including a backlight unit and a liquid crystal display panel according to the present invention, and FIG. 5A is a case where no voltage is applied to the switching lens sheet (narrow view angle mode). 5B illustrates a case where a voltage is applied to the switching lens sheet (wide viewing angle mode).

5A and 5B, in the switching lens sheet 200, a first transparent electrode layer 213 is formed on a glass substrate 211, and a first alignment layer 215 is formed on the first transparent electrode layer 213. ) Is formed.

In addition, a concave groove (not shown) is formed on the lower surface of the lenticular substrate 221, and a second alignment layer 223 is formed on the lower surface including the groove, and the upper surface of the lenticular substrate 221 is formed. Two transparent electrode layers 225 are formed.

The liquid crystal layer 231 is filled in a space formed by the glass substrate 211 and the lens-shaped substrate 221 bonded to each other.

Referring to FIG. 5A, according to the switching lens sheet 200 configured as described above, since the liquid crystal 231 is an anisotropic material, refractive indices have “Ne” and “No”. The glass substrate 211 and the lens When no voltage is applied to the mold substrate 221, the liquid crystal 231 is oriented due to the alignment film so that the refractive index in the light propagation direction has only a value of "Ne". At this time, the refractive index N1 of the lenticular substrate 221 is larger than the refractive index Ne of the liquid crystal 231, so that the liquid crystal 231 forms a convex lens.

Therefore, the light emitted through the light guide plate 210 passes through the second alignment layer 223 and the lenticular substrate 221, so that the light path 241a is changed, so that the viewing angle of the light is narrowed.

On the other hand, referring to FIG. 5B, when a voltage of about 5 V is applied to the glass substrate 211 and the lenticular substrate 221, the liquid crystal 231 is aligned perpendicular to the lenticular substrate 221. The refractive index of the light traveling direction, that is, the refractive index of the liquid crystal has only a "No" value. At this time, the refractive index N1 of the lenticular substrate 221 is equal to the refractive index No of the liquid crystal, so that the liquid crystal 231 does not function as a lens. Therefore, the light emitted through the light guide plate 210 does not change the path of light 241b while passing through the lens-shaped substrate 221, thereby widening the viewing angle of the light.

In addition, as another embodiment of the switching lens according to the present invention, the light path through the operation principle of the liquid lens (liquid lens) 300 using the electron-wetting phenomenon will be described with reference to Figs. 6a and 6b. Is as follows.

6A and 6B are cross-sectional views of a switching lens sheet structure applied to a liquid crystal display device including a backlight unit and a liquid crystal display panel according to the present invention. FIG. 6A illustrates a liquid lens method using an electronic-wetting phenomenon. FIG. 6B is a schematic diagram illustrating a path change of light that appears when no voltage is applied to a liquid lens, and FIG. 6B is a schematic diagram illustrating a path change of light that appears when a voltage is applied to a liquid lens.

Referring to FIGS. 6A and 6B, the liquid lens 300 has a conductivity such as water between the first glass substrate 311 and the second glass substrate 321 having the hydrophobic thin film 323 formed on the bottom surface thereof. The fluid layer 331 is filled with a hydrophobic fluid layer 333 such as oil, and an insulating layer 335 is formed between the second glass substrate 321 and the conductive fluid layer 331 and the hydrophobic fluid layer 333. Intervened. At this time, since the conductive fluid layer 331, that is, water dislikes hydrophobicity, there is a property of avoiding contact as much as possible.

In addition, a partition wall 325 is provided between the first glass substrate 311 and the second glass substrate 321, and an electrode 341 (outside the first glass substrate 311 and the partition wall 325) is provided. 343) are provided respectively. In this case, the electrodes 341 and 343 are electrically insulated from each other.

According to the above configuration, as in FIG. 6A, the water 331 has a round hemispherical shape. If the refractive index of the water 331 is greater than that of the oil 333, the convex lens may function.

In addition, as shown in FIG. 6B, when a voltage is applied to the upper and lower electrodes 341 and 343, water 331, which has been disliked hydrophobicity, is forcibly pushed toward the hydrophobic thin film 323 by an electric field so that a semicircle forms a flat plane. As a result, the wide viewing angle mode is formed.

In the liquid lens 300 configured as described above, as shown in FIG. 6A, when no voltage is applied to the upper and lower electrodes 341 and 343, the ratio of the hydrophobic fluid layer 333 is greater than that of the conductive fluid layer 331. As the ratio increases, the incident light 361a and 361b passing through the second glass substrate 321 is emitted in all directions while passing through the conductive fluid layer 331, thereby having a wide viewing angle.

On the other hand, as shown in FIG. 6B, when the voltage is applied to the upper and lower electrodes 341 and 343, the incident light 361a and 361b passing through the second glass substrate 321 is the conductive fluid layer 331. As the light passes through the light, the light is focused and emitted, thereby narrowing the viewing angle.

As described above, according to the liquid crystal display device capable of switching the narrow viewing angle mode according to the present invention, the switching lens sheet is inserted between the backlight unit and the liquid crystal display panel or on the front surface of the liquid crystal display panel, thereby using the switching lens to display the liquid crystal display. By adjusting the path of light emitted from the backlight unit or the liquid crystal display panel in the device, the viewing angle of the liquid crystal display panel can be adjusted to the wide viewing angle mode or the narrow viewing angle mode as necessary.

Therefore, the use of the switching lens can reduce the field of view in a place where security is required according to the purpose can be viewed only by the operator and can be used to adjust the viewing angle in a wide range of times.

On the other hand, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the technical spirit of the present 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.

Claims (10)

A backlight unit for supplying a light source; A switching lens sheet for changing the traveling path of the light to a narrow viewing angle mode; And And a liquid crystal display panel configured to display an image on a screen through light traveling through the switching lens sheet. 2. The liquid crystal display of claim 1, wherein the backlight unit comprises a light guide plate. The liquid crystal display device according to claim 2, wherein a diffusion sheet is provided between the light guide plate and the switching lens sheet. The liquid crystal display device according to claim 1, wherein a protective sheet is provided between the switching lens sheet and the liquid crystal display panel. The liquid crystal display of claim 1, wherein the switching lens sheet is positioned between the backlight unit and the liquid crystal display panel or on the liquid crystal display panel. The liquid crystal display of claim 1, wherein the switching lens sheet comprises a switching lens using liquid crystal or a liquid lens using an electron-wetting phenomenon. The method of claim 6, wherein the switching lens using the liquid crystal, A lens substrate having a plurality of grooves formed on a glass substrate and a lower surface thereof, A first transparent electrode layer formed on the glass substrate; A first alignment layer formed on the first transparent electrode layer; A second alignment layer formed on a lower surface of the lens substrate including a groove; A liquid crystal layer injected into a space formed by bonding the glass substrate and the lenticular substrate together; And a second transparent electrode layer formed on the lenticular substrate. The method of claim 7, wherein a narrow viewing angle mode is formed when a voltage is applied to the switching lens using the liquid crystal, and a wide viewing angle mode is formed when no voltage is applied to the switching lens using the liquid crystal. LCD display device. The liquid lens of claim 6, wherein the liquid lens using the electron-wetting phenomenon is A first glass substrate, a second glass substrate having a hydrophobic thin film formed on its lower surface, Barrier ribs provided between the first glass substrate and the second glass substrate; A hydrophobic fluid layer and a conductive fluid layer filled in a space formed by the first glass substrate and the second glass substrate; An insulating layer interposed between the hydrophobic fluid layer and the conductive fluid layer, the partition wall and the second glass substrate, And an electrode provided on each of the first and second glass substrates. 10. The method of claim 9, wherein a narrow viewing angle mode is formed when a voltage is applied to the liquid lens using the electron-wetting phenomenon, and a wide viewing angle mode is formed when a voltage is not applied to the liquid lens. Liquid crystal display device.

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