KR100350639B1 - Liquid crystal displays and viewing-angle control methods in the same - Google Patents

Abstract

The first common electrode is formed of a transparent conductive material such as indium-tin-oxide (ITO) on the entire lower substrate, and an insulating film is covered thereon, and a plurality of pixel electrodes parallel to each other are formed on the insulating film. The upper substrate corresponds to face the lower substrate, and a second common electrode is formed on the front surface of the substrate with a bright conductive material, and a liquid crystal layer is injected between the two substrates. A first common voltage having a predetermined magnitude is always applied to the first common electrode of the liquid crystal display, and a second common voltage equal to or different from the first common voltage is applied to the second common electrode. In this case, when the second common voltage is appropriately varied as necessary to adjust the difference between the first common voltage and the second common voltage, the magnitude of the voltage applied to the lower and upper substrates is adjusted. Their pretilt angle is adjusted. As the pretilt angle of the liquid crystal molecules increases, the viewing angle becomes narrower because the anisotropy of the liquid crystal increases. As a result, the narrow viewing angle or the wide viewing angle may be appropriately adjusted by increasing or decreasing the pretilt angle of the liquid crystal molecules in a manner of increasing or decreasing the difference between the voltage applied to the first common electrode and the voltage applied to the second common electrode.

Description

Liquid crystal display and its viewing angle adjustment method {LIQUID CRYSTAL DISPLAYS AND VIEWING-ANGLE CONTROL METHODS IN THE SAME}

The present invention relates to a liquid crystal display device and a viewing angle adjusting method thereof.

A typical flat panel display device is a liquid crystal display device which injects liquid crystal between two substrates and adjusts the light transmittance by controlling the intensity of the electric field applied to the electrodes formed on the substrate surface. It is widely used in fields such as TVs and various portable electronic products. In recent years, as the needs of users become more and more diverse, various liquid crystal modes capable of increasing the size of a liquid crystal display, high definition, wide viewing angle, and the like have been proposed.

As a representative example of a liquid crystal display device having a wide viewing angle characteristic, a liquid crystal display device having a vertical alignment (VA) method to which a transverse electric field drive type liquid crystal display device and a compensation film is applied may be mentioned.

In a transverse electric field drive type liquid crystal display device in which a pixel electrode and a common electrode are formed on the same substrate, a horizontal electric field is formed on the substrate surface between the pixel electrode and the common electrode when the pixel is turned on, so that the pixel is turned on. On off, the long axis of the liquid crystal molecules operates parallel to the substrate surface. Therefore, the refractive index of the liquid crystal observed macroscopically is small, and the contrast ratio is good and it is advantageous to a wide viewing angle.

Meanwhile, a vertical alignment liquid crystal display device includes a pair of transparent substrates having transparent electrodes formed on an inner surface thereof, a liquid crystal material injected between two substrates, and oriented perpendicular to the substrate surface, on an outer surface of each transparent substrate. It consists of two polarizing plates attached to each other so as to be orthogonal to each other to polarize light, and implements a wide viewing angle by attaching a compensation film inside the polarizing plate to compensate for the viewing angle. Recently, a mode of multi-dividing without rubbing has been proposed by forming an opening pattern or forming a projection in the transparent electrode.

However, the liquid crystal display of the wide viewing angle mode is disadvantageous compared to other modes when the narrow viewing angle is required for confidentiality and security.

An object of the present invention is to provide a liquid crystal display device that can adjust the wide viewing angle and narrow narrow angle as needed.

1A and 1B are a layout view and a cross-sectional view of a transverse electric field drive type liquid crystal display device, which is a layout view and a cross-sectional view schematically showing an arrangement of liquid crystals in an off state pixel;

2A and 2B are a layout view and a cross-sectional view of a transverse electric field driving type liquid crystal display device, which is a layout view and a cross-sectional view schematically showing an arrangement of liquid crystals in a pixel in an on state;

3 is a plan view showing the operation of the liquid crystal in the transverse electric field drive type liquid crystal display device,

4 is a cross-sectional view schematically illustrating a principle of adjusting a viewing angle as a view for comparing optical characteristics of liquid crystal molecules inclined with different pretilt angles with respect to a substrate surface.

5 is a cross-sectional view illustrating an electric field shape in a liquid crystal display according to a first exemplary embodiment of the present invention.

6 is a cross-sectional view illustrating an arrangement of liquid crystals according to the electric field of FIG. 5.

7 is a cross-sectional view illustrating an arrangement of liquid crystals in a liquid crystal display according to a second exemplary embodiment of the present invention.

8 is a cross-sectional view illustrating a state in which liquid crystals of a vertical alignment liquid crystal display are arranged perpendicularly to a substrate surface;

9 is a cross-sectional view illustrating a state in which liquid crystals of a vertical alignment liquid crystal display are arranged at a predetermined angle on a substrate surface;

FIG. 10 is a schematic diagram for comparing characteristics of viewing angle characteristics of liquid crystal molecules inclined at different angles with respect to an axis perpendicular to a substrate plane;

11 is a layout view of a liquid crystal display device according to a third and fourth exemplary embodiment of the present invention.

12 is a cross-sectional view of a third embodiment of the present invention for the line XII-XII ′ in FIG. 11,

FIG. 13 is a cross-sectional view of a fourth embodiment of the present invention for the line XII-XII ′ in FIG. 11,

14 is a layout view of a liquid crystal display according to a fifth exemplary embodiment of the present invention.

15 is a layout view of a liquid crystal display according to a sixth exemplary embodiment of the present invention.

16 is a cross-sectional view taken along line XVI-XVI 'of FIG. 15,

17 is a layout view of a liquid crystal display according to a seventh exemplary embodiment of the present invention.

In order to solve the above problems, in the liquid crystal display according to the present invention, a separate viewing angle adjusting electrode is provided, and the voltage difference between the viewing angle adjusting electrode and the corresponding electrode is varied to adjust the pretilt angle of the liquid crystal molecules positioned therebetween. do.

In the liquid crystal display device to which the viewing angle adjusting method according to the exemplary embodiment of the present invention is applied, first and second electrodes are formed on a first substrate, and first and second electrodes are disposed on a second substrate facing the first substrate. A third electrode is formed to face each other, and a liquid crystal layer is injected between the two substrates. In such a liquid crystal display, display is implemented by a difference in voltage applied between the first electrode and the third electrode, and the initial stage of the liquid crystal of the liquid crystal layer is controlled by adjusting a difference in voltage applied between the second electrode and the third electrode. Adjust the viewing angle by maintaining or changing the pretilt angle.

The initial pretilt angle of the liquid crystal may be in a direction perpendicular to the surface of the first and second substrates, wherein the liquid crystal preferably has negative dielectric anisotropy suitable for the vertical alignment mode.

The data voltage and the common voltage or the common voltage and the data voltage may be applied to the first electrode and the third electrode, respectively.

In the liquid crystal display device to which the viewing angle adjusting method is applied according to another embodiment of the present invention, a first common electrode for applying a common voltage is formed on the first substrate, and the pixel electrode is formed to be insulated from the first common electrode. 1 is formed on the substrate. The second substrate corresponds to face the first substrate, the second common electrode is formed on the second substrate to face the first common electrode and the pixel electrode, and the liquid crystal layer is injected between the first and second substrates. have. In the liquid crystal display, the viewing angle is adjusted by maintaining or changing the direction of the liquid crystal initial pretilt angle of the liquid crystal layer by adjusting a difference in voltage applied between the first common electrode and the second common electrode.

The direction of the initial pretilt angle of the liquid crystal may be a direction parallel to the first and second substrate surfaces, in which case the liquid crystal preferably has positive dielectric anisotropy.

Meanwhile, the liquid crystal display according to the exemplary embodiment of the present invention includes a viewing angle adjusting region in which each pixel formed on the first substrate is positioned outside the display region and the display region, and on the first substrate of the viewing angle adjusting region. 1 The electrode for viewing angle adjustment is formed. In addition, a first electrode is formed on the first substrate of the display area. The second substrate corresponds to face the first substrate, the second electrode is formed on the second substrate so as to face the first electrode and the first viewing angle adjusting electrode, and a liquid crystal layer is injected between the two substrates.

The first electrode and the second electrode are electrodes for applying a data signal voltage and a common signal voltage or a common signal voltage and a data signal voltage for driving the pixel, respectively, and the first viewing angle adjusting electrode is separate from the first or second electrode. It is preferably an electrode for variably applying a voltage of.

The first projection pattern is formed on the first viewing angle electrode, the first vertical alignment layer is coated on the first viewing angle electrode, and the second projection pattern is alternately formed in parallel with the first projection pattern on the second electrode of the viewing angle adjusting region. have. It is preferable that a 2nd vertical alignment film is apply | coated on this 2nd projection pattern, and the 1st and 2nd polarizing plate is affixed on the outer surface of a 1st and 2nd board | substrate. In this case, the polarization axis directions of the two polarizing plates may be perpendicular to each other.

The second viewing angle adjusting electrode extends vertically from the first viewing angle adjusting electrode, and a third projection pattern is formed thereon in the same direction as the second viewing angle adjusting electrode, and the third projection pattern is formed on the second electrode of the viewing angle adjusting region. Alternately, the fourth drowsiness pattern may be formed.

Here, it is preferable that the liquid crystal of a liquid crystal layer is negative dielectric anisotropy.

An opening pattern may be formed instead of the protrusion pattern. In this case, the second opening of the viewing angle adjusting region is formed with the first opening in the same direction as the first viewing angle adjusting electrode at a position facing the first viewing angle adjusting electrode. The second opening pattern is formed at the position facing the second viewing angle adjusting electrode in the same direction as the second viewing angle adjusting electrode.

In the liquid crystal display according to the exemplary embodiment of the present invention, a first common electrode is formed on the surface of the first substrate, an insulating film is covered thereon, and a plurality of pixel electrodes are formed parallel to each other. The second substrate corresponds to face the first substrate, and a transparent second common electrode is formed on an entire surface of the second substrate.

The first common electrode may be formed on the entire surface of the first substrate using a transparent conductive material, or may be formed in plurality in parallel with the pixel electrode.

The liquid crystal layer is injected between the first and second substrates, and a voltage different from the pixel electrode and the first common electrode is applied to the second common electrode, and the voltage difference with the first common electrode is adjusted to adjust the voltage of the liquid crystal layer. The pretilt angle of the liquid crystal with respect to the first and second substrate surfaces is adjusted.

Next, a liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

First, a liquid crystal array in a transverse electric field driving type liquid crystal display device will be described with reference to FIGS. 1A to 2B.

1A and 1B are a layout view and a cross-sectional view schematically showing an arrangement of liquid crystals in a pixel in an off state, and FIGS. 2A and 2B are a layout view schematically showing an arrangement of liquid crystals in a pixel in an on state. And cross section.

1A and 1B, a gate line 100 to which a scan signal is applied in a horizontal direction is formed on the lower insulating substrate 10, and the common electrode line 110 is parallel to the gate line 100. The plurality of common electrodes 120 extend from the common electrode line 110 in the vertical direction. The insulating film 30 covers the gate line 100, the common electrode line 110, and the common electrode 120, and a data line 200 for applying a data signal is formed on the insulating film 30 in a vertical direction. A thin film transistor TFT is formed in the pixel surrounded by the gate line 100 and the data line 200. The gate terminal g of the thin film transistor is connected to the gate line 100, and the source terminal s is connected to the data line 200. The pixel electrode line 210 extends in the horizontal direction from the drain terminal d of the thin film transistor, and the plurality of pixel electrodes 220 extend in parallel with the common electrode 120 from the pixel electrode line 210. 220 is alternately arranged with the common electrode 120. The lower insulating substrate 10 corresponds to face the upper insulating substrate 20, and a positive dielectric anisotropic liquid crystal 41 having the property that the major axes of the liquid crystals are arranged in the direction of the electric field between the two substrates 10 and 20. ) Is injected. A voltage equal to a common voltage is always applied to the common electrode line 110 and the common electrode 120, and the thin film transistor TFT is opened on the pixel electrode line 210 and the pixel electrode 220, and is simultaneously removed from the data line 200. The data signal is applied.

In the initial arrangement of the liquid crystal 41, as shown in FIGS. 1A and 1B, the long axis of the liquid crystal 41 is parallel to the common electrode 120 and the pixel electrode 220 or has a predetermined angle, and the two substrates ( 10, 20) almost parallel to the plane. This initial state is maintained when the thin film transistor is turned off.

When the thin film transistor is turned on and a data signal is applied to the pixel electrode 220, as shown in FIGS. 2A and 2B, the liquid crystal 41 positioned near the substrate 10 and 20 may be the substrate 10 or 20. Although the initial state is maintained parallel or at a predetermined angle to the common electrode 120 and the pixel electrode 220 by the surface orientation force, the long axis of the liquid crystal 42 is the common electrode 120 and the pixel electrode 220 in the remaining portion. Rotate so that it is aligned perpendicular to). Even in this case, the liquid crystals 41 and 42 rotate almost parallel to the surfaces of the two substrates 10 and 20.

3 is a plan view illustrating an operation of a liquid crystal as the thin film transistor is turned on and off.

As mentioned above, in the transverse electric field drive type liquid crystal display device, the liquid crystals 41 and 42 operate almost in parallel with the substrate 10 and 20 planes while the thin film transistors of the pixels are on and off. As shown in FIG. 3, assuming that the substrates 10 and 20 are located in the xy plane, and the pixel electrode 220 and the common electrode 120 lie in the x axis direction, the liquid crystal 41 is on the x axis. Rotate within each range Δα (α2-α1) from the initial angle α1 to the maximum angle α2.

Thus, since the liquid crystals 41 and 42 are driven in the horizontal plane, a wide viewing angle can be obtained.

On the other hand, a narrow viewing angle may be required in some cases even in a liquid crystal display device employing a transverse electric field driving method which is advantageous for a wide viewing angle. Next, the principle of adjusting the viewing angle of the hierarchical drive type liquid crystal display device will be described.

4 is a cross-sectional view for comparing optical characteristics of liquid crystal molecules that are inclined at different line inclination angles with respect to the substrate surface, and the z axis is a normal axis with respect to the substrate surface.

FIG. 4A shows a state in which liquid crystal molecules 43 are aligned almost parallel to the surface of the substrate 10. In order to obtain a wide viewing angle, the pretilt angle θ _p1 is minimized in the transverse electric field driving method as shown in FIG. 4A. In this case, optical properties such as transmittance at positions x ₁ and x ₂ deviated by the same angle θ from the normal axis z are almost isotropic, so that a wide viewing angle is realized.

As shown in (b) of FIG. 4, when oriented to have a larger pretilt angle θ _p2 than in FIG. 4 (a), the position x ₁ deviated by the same angle θ from the normal axis z. , since the larger the optical anisotropy of the properties such as the transmittance of the x _2), the viewing angle becomes narrower than that in Figure 4 (a).

FIG. 4C shows a case where the line inclination angle θ _p3 is greater with respect to the surface of the substrate 10 than in FIGS. 4A and 4B, and is equal to the same angle θ from the normal axis z. Since the anisotropy of the optical characteristic at the off position x ₁ , x ₂ becomes larger, the viewing angle becomes narrower.

As a result, as shown in FIG. 3, the display is implemented by operating the liquid crystal on a horizontal plane. As shown in FIG. 4, when the pretilt angle of the liquid crystal is adjusted, a wide viewing angle or a narrow viewing angle may be implemented as necessary.

Embodiments of the present invention using the viewing angle adjustment principle described above will be described below.

FIG. 5 is a cross-sectional view illustrating the shape of an electric field in the liquid crystal display according to the first exemplary embodiment of the present invention, and FIG. 6 is a cross-sectional view illustrating an arrangement of liquid crystals according to the electric field of FIG. 5.

As shown in FIGS. 5 and 6, the first common electrode 130 is formed on the lower insulating substrate 10 with a transparent material such as indium-tin-oxide (ITO) over the entire surface of the lower insulating substrate 10, and an insulating film is formed thereon. 30 is covered, and a plurality of pixel electrodes 230 parallel to each other are formed on the insulating film 30 per pixel. The pixel electrode 230 is electrically connected to a drain electrode (not shown) of the thin film transistor. A second common electrode 140 is formed on a front surface of the upper insulating substrate 20 corresponding to the lower insulating substrate 10 with a transparent material such as ITO, and between the lower and upper insulating substrates 10 and 20. The liquid crystal layer 40 is injected.

In such a liquid crystal display, the wide viewing angle and the narrow viewing angle may be appropriately adjusted by appropriately adjusting the voltage applied to the second common electrode 140. That is, a first common voltage having a predetermined magnitude is always applied to the first common electrode 130, and a second common voltage equal to or different from the first common voltage is applied to the second common electrode 140. In this case, when the second common voltage is appropriately varied as necessary to adjust the difference between the first common voltage and the second common voltage, the magnitude of the voltage applied between the lower and upper insulating substrates 10 and 20 is adjusted. The pretilt angles of the liquid crystal molecules 46 and 47 are adjusted according to the magnitude of the voltage. As the pretilt angle is adjusted, the viewing angle is also adjusted for the same reasons as mentioned above.

When a second common voltage different from the first common voltage is applied to the second common electrode 140 of the upper insulating substrate 20, the electric field formed between the two substrates 10 and 20 of the liquid crystal display is shown in FIG. 5. As shown. In the open pixel ON PIXEL, an electric field E _on substantially parallel to the substrate 10 is formed between the first common electrode 130 and the pixel electrode 230, and in the closed pixel OFF PIXEL, two substrates 10 are formed. , 20) a vertical electric field E _off is formed. In practice, these electric fields E _on and E _{off are} formed between the pixel electrode 230 and the first common electrode 130 in parallel to the surfaces of the substrates 10 and 20 and the first and second common electrodes 130. , 140, which is a force of an electric field formed perpendicular to the surfaces of the substrates 10 and 20, between the open pixels ON PIXEL and the closed pixels OFF PIXEL under the influence of the vertical components of the electric fields E _on and E _off . The liquid crystal molecules 46 and 47 operate with a constant pretilt angle as shown in FIG. As mentioned above, the pretilt angle can be varied by adjusting the magnitude of the voltage applied to the second common electrode 140. As the pretilt angle increases, the anisotropy of the liquid crystal molecules 46 and 47 increases. Narrows.

As a result, by increasing or decreasing the pretilt angles of the liquid crystal molecules 46 and 47 in a manner of increasing or decreasing the difference between the voltage applied to the first common electrode 130 and the voltage applied to the second common electrode 140. Narrow viewing angle or wide viewing angle can be adjusted accordingly.

A second embodiment having a structure capable of adjusting the narrow viewing angle and wide viewing angle is shown in FIG. 7.

7 is a cross-sectional view illustrating an arrangement of liquid crystals in a liquid crystal display according to a second exemplary embodiment of the present invention.

As illustrated in FIG. 7, gate lines (not shown) and first common electrodes 150 are formed on the lower insulating substrate 10 as a metal for gate wiring, and a plurality of gate lines may be formed per pixel. The insulating layer 30 covers the gate line and the first common electrode 150, and a plurality of pixel electrodes 240 are formed on the insulating layer 30 in parallel with the first common electrode 150.

The upper insulating substrate 20 corresponds to face the lower insulating substrate 10, and the second common electrode 140 is formed on the surface of the substrate 20 using a transparent conductive material such as ITO.

The liquid crystal layer 40 is injected between the two substrates 10 and 20.

When no voltage is applied to the second common electrode 140 of the liquid crystal display, in the open pixel ON PIXEL to which the data voltage is applied to the pixel electrode 240, the liquid crystal molecules 46 are connected to the pixel electrode 240. It operates so as to be perpendicular to the first common electrode 150, and maintains an initial state in which the liquid crystal molecules 47 are arranged parallel to the pixel electrode 240 and the first common electrode 150 in the OFF pixel. do.

When a voltage is applied to the second common electrode 140, as shown in FIG. 7 due to the electric field of the vertical component generated between the upper second common electrode 140 and the lower first common electrode 150. The liquid crystal molecules 47 operate with a predetermined pretilt angle with respect to the surface of the substrate 10.

As described above, the viewing angle range is determined according to the pretilt angle of the liquid crystal molecules 47 in the transverse electric field driving type liquid crystal display, and thus the viewing angle is adjusted by varying the voltage applied to the second common electrode 150. Can be.

Next, a liquid crystal display device of a vertical alignment method capable of adjusting the viewing angle will be described.

FIG. 8 is a cross-sectional view schematically illustrating a state in which liquid crystals of a vertically aligned liquid crystal display are arranged perpendicular to the substrate surface, and FIG. 9 is a state in which liquid crystals of the vertically aligned liquid crystal display are arranged at an angle to the substrate surface. It is a cross section showing.

8 and 9, in the vertical alignment liquid crystal display, the transparent electrode 160 is formed on one surface of the lower insulating substrate 10, and the vertical alignment layer 180 is coated on the transparent electrode 160. It is. The polarizing plate 1 is attached to the other side of the substrate 10, and a compensation film 70 is attached between the surface of the substrate 10 and the polarizing plate 1 to compensate for the delay of light.

The transparent electrode 170 is formed on one surface of the upper insulating substrate 20, the vertical alignment layer 180 is coated thereon, and the polarizing plate 2 is attached to the other surface of the substrate 20.

The upper and lower insulating substrates 20 and 10 correspond to the vertical alignment layers 180 facing each other, and the polarization axes of the polarizing plates 1 and 2 are assembled to be perpendicular to each other. A liquid crystal layer 50 having negative dielectric anisotropy in which the long axis of the liquid crystal molecules is perpendicular to the direction of the electric field is injected between the two substrates 20 and 10.

As shown in FIG. 8, in the state in which no electric field is applied from the outside, the long axes of the liquid crystal molecules of the liquid crystal layer 50 are perpendicular to the surface of the substrates 20 and 10 by the alignment force of the vertical alignment layer 180. Are oriented. When the liquid crystal molecules are arranged perpendicularly to the planes of the substrates 20 and 10 as described above, when light linearly polarized in the polarizing plate 1 of the lower substrate 10 passes through the liquid crystal layer 50, Since the delay hardly occurs, most of the light is blocked in the polarizing plate 2 of the upper substrate 20. Therefore, the contrast ratio is improved and the viewing angle is good.

On the other hand, as shown in FIG. 9, when the liquid crystal molecules of the liquid crystal layer 50 are inclined at a predetermined angle φ in the polarization axis directions of the polarizers 1 and 2, the polarizing plate 1 of the lower substrate 10. Since the light linearly polarized in the y-axis direction through () is elliptically polarized while passing through the liquid crystal layer 50, when the light passes through the polarizing plate 2 of the upper substrate 20, that is, the x-axis direction that is the polarization axis direction, that is, Light leaks from the direction perpendicular to the direction in which the liquid crystal molecules are inclined. Therefore, the viewing angle characteristic is relatively lowered.

The relationship between the degree of tilt of the liquid crystal molecules and the viewing angle will be further described with reference to FIG. 10.

FIG. 10 is a schematic diagram for comparing characteristics of viewing angle characteristics according to an angle at which liquid crystal molecules are inclined with respect to an axis perpendicular to a substrate plane. FIG.

10A illustrates a state in which no electric field is applied to the liquid crystal molecules 51.

In fact, in order to give the direction in which the liquid crystal molecules operate when an electric field is applied, the liquid crystal molecules 51 in the initial state have a nearly negligible line diameter (φ ₁ ≒ 0 °) with respect to the vertical axis z of the substrate 10. It is oriented to have a square. The liquid crystal molecules 51 oriented in this manner have almost isotropic optical characteristics with respect to planar components, and therefore light is hardly leaked at 80 degrees or more in the horizontal direction. Therefore, the viewing angle is good.

10 (b) and 10 (c) show a state in which an electric field is applied to the liquid crystal molecules 52 and 53.

The liquid crystal molecules 52 of FIG. 10B have a state in which an electric field is applied such that the pretilt angle φ ₂ has a value larger than the pretilt angle φ ₁ of the liquid crystal molecules 51 in (a). Although the light still leaks from the front side, the farther the field of view from the vertical axis z, the greater the anisotropy of the liquid crystal and the more light is counted. Therefore, the viewing angle is narrowed.

The pretilt angle φ ₃ of the liquid crystal molecules 53 of FIG. 10C is a state in which an electric field is applied to have a value larger than the pretilt angle φ ₂ of the liquid crystal molecules 52 in (b). This becomes even narrower.

Embodiments of the present invention for implementing the wide viewing angle and the narrow viewing angle as needed using this principle are described below.

FIG. 11 is a layout view of a vertically aligned liquid crystal display according to a third exemplary embodiment of the present invention, and FIG. 12 is a cross-sectional view of the third exemplary embodiment of the present invention with respect to the XII-XII ′ line of FIG. 11, showing only one pixel. have.

As shown in FIGS. 11 and 12, the liquid crystal display device includes a lower substrate as a thin film transistor substrate and an upper substrate as a color filter substrate.

Although not shown in the drawing, the lower substrate 10 has gate lines and data lines intersecting with each other, and an area surrounded by the gate lines and data lines becomes a pixel. One pixel is formed by dividing a pattern into two parts, an area for display and an area for adjusting a viewing angle, and a thin film transistor (not shown) for switching pixels is formed in the area for display. The insulating film 31 is covered thereon, and the transparent pixel electrode 160 is formed in the pixel on the insulating film 31.

The projection 11 is formed on the pixel electrode 160. The projection 11 is formed in the shape of the sawtooth bent in the vertical center portion of the pixel in the display area, and the projection 11 in the region for adjusting the viewing angle. 21 is formed in the horizontal direction.

The vertical alignment layer 180 is disposed on the protrusions 11 and 21 and the pixel electrode 160 to vertically align the liquid crystal molecules.

The black matrix 80 is formed on the upper substrate 20 facing the lower substrate 10 so as to cover a boundary between an area for display and an area for adjusting a viewing angle and an edge of a pixel of the lower substrate 10. The color filter 90 is formed between the black matrices 80. This color filter 90 may be formed in the whole area | region of a pixel, and may be formed only in the area | region for display. When only the display area is formed, an organic film (not shown) may be formed in the area for adjusting the viewing angle to correct the step instead of the color filter.

A protective insulating film (not shown) covering the black matrix 80, the color filter 90, and the organic film covers the entire surface of the substrate, and transparent electrode patterns 170 and 171 are formed thereon. As shown in FIG. 12, the electrode patterns 170 and 171 are patterned by being divided into an area for display and an area for adjusting a viewing angle. In other words, the common electrode 170 of the portion corresponding to the display area and the viewing angle adjustment electrode 171 of the portion corresponding to the area for viewing angle are separated. A common voltage of direct current or alternating current is always applied to the common electrode 170, and a voltage is applied to the viewing angle adjusting electrode 171 by varying the size as necessary, based on a common voltage applied to the common electrode 170. Let's reverse this.

The protrusions 12 and 22 are formed on the common electrode 170 and the viewing angle adjusting electrode 171. The protrusions 12 formed on the common electrode 170 are formed in the shape of teeth serrated at the center of the display area, and are alternately arranged with the protrusions 11 formed on the thin film transistor substrate. The region 22 for adjusting the viewing angle, that is, the protrusion 22 formed on the viewing angle adjusting electrode 171 is formed in the horizontal direction, and is alternately disposed with the protrusion 21 formed on the thin film transistor substrate.

The vertical alignment layer 180 covering the protrusions 12 and 22 is coated.

The liquid crystal layer 50 is injected between the two substrates 10 and 20. The liquid crystal molecules of the liquid crystal layer 50 are initially aligned vertically between the two substrates 10 and 20 by the alignment force of the vertical alignment layer 180.

Polarizers 1 and 2 are attached to the outer sides of the two substrates 10 and 20, respectively, and the polarization directions P1 and P2 of the two polarizers 1 and 2 are arranged to be perpendicular to each other in the horizontal and vertical directions, respectively. .

Compensation films may be attached between the surfaces of the substrates 10 and 20 and the polarizing plates 1 and 2.

In the structure having the electrodes 160, 170, 171 and the protrusions 11, 21, 12, and 22, the common electrode 170 and the pixel electrode 160 formed in the display area are used to drive pixels. Voltage is applied respectively. That is, the common voltage is always applied to the common electrode 170, and the data voltage is applied or not applied to the pixel electrode 160 of the lower substrate 10 as the thin film transistor of the pixel is turned on or off. .

When the thin film transistor is in an open state and a data voltage is applied to the pixel electrode 160, the directors of the liquid crystal molecules of the liquid crystal layer 50 face the protrusions 11 and 12 of the upper and lower substrates 20 and 10. Since they are arranged perpendicular to the furnace projections 11 and 12, four regions with different orientations are formed. In addition, when no voltage is applied to the pixel electrode 160, the arrangement of the liquid crystal molecules maintains an initial state.

On the other hand, a voltage is variably applied to the viewing angle adjusting electrode 171 formed in the region for adjusting the viewing angle of the pixel according to the required viewing angle mode. This is described in more detail.

The voltage is applied to the viewing angle adjusting electrode 171 of the upper substrate 20 so that a voltage difference between the pixel electrode 160 of the lower substrate 10 and the viewing angle adjusting electrode 171 of the upper substrate 20 does not occur. In this case, the liquid crystal molecules in the region for adjusting the viewing angle are arranged perpendicular to the surface of the substrate 10 and 20 in the initial state. As such, when the long axes of the liquid crystal molecules are arranged perpendicular to the substrate surface, the contrast ratio of the area for adjusting the viewing angle is improved, so that the area for adjusting the viewing angle does not affect the viewing angle of the area for display. Thus, the wide viewing angle mode is maintained.

On the other hand, when a voltage is applied to the viewing angle adjusting electrode 171 so that a voltage difference of a predetermined magnitude is generated between the voltage applied to the pixel electrode 160 and the viewing angle adjusting electrode 171, the region of the liquid crystal molecules is used to adjust the viewing angle. The long axis is arranged perpendicularly to the protrusions 21 and 22 in a form facing the protrusions 21 of the upper substrate 20 and the protrusions 22 of the lower substrate 10. That is, the director of the liquid crystal molecules is placed parallel to the vertical polarization direction P2. As mentioned above with reference to FIG. 10, the liquid crystal molecules lie at an angle with respect to the surface of the substrates 10 and 20, and are arranged perpendicular to the direction of the polarization axis of one of the two polarizing plates 1 and 2. The light leaks from the left and right directions in the vertical direction of the lying down direction. In this case, the viewing angle of the area for display is affected, and the left and right viewing angles are narrowed as a whole.

The left and right viewing angles become narrower as the difference between the voltages applied to the pixel electrode 160 and the viewing angle adjusting electrode 171 becomes larger. This is because the range of the anisotropy of the liquid crystal increases as the range moves away from the front side.

As such, by properly varying the voltage applied to the viewing angle adjusting electrode 171, a wide viewing angle or a narrow viewing angle may be appropriately implemented.

Although the case where the viewing angle adjustment electrode is formed in the upper substrate so far has been described, the effect is the same even if it is formed in the lower substrate. This fourth embodiment will be described with reference to FIG.

FIG. 13 is a cross-sectional view of a fourth embodiment of the present invention taken along line XII-XII ′ of FIG. 11.

As shown in Fig. 13, the structure according to the fourth embodiment is almost the same as in the third embodiment. However, the common electrode 170 is formed over the entire surface of the upper substrate 20, and instead, the viewing angle adjusting electrode 161 is formed on the lower substrate 10. The viewing angle adjusting electrode 161 is formed of the same material on the same layer as the pixel electrode 160 and is positioned outside the pixel electrode 160. The viewing angle adjusting electrode 161 is bundled separately from the pixel electrode 160 to apply a voltage regardless of the driving voltage of the pixel electrode 160.

By adjusting the voltage applied to the viewing angle adjusting electrode 161 in the same manner as in the first embodiment described above, a narrow viewing angle or a wide viewing angle is realized in the left and right directions.

The third and fourth embodiments of the present invention were modes for adjusting the viewing angle in the left and right directions, but the viewing angles in the up and down directions may be simultaneously adjusted. This fifth embodiment will be described below with reference to FIG.

14 is a layout view of a liquid crystal display according to a fifth exemplary embodiment of the present invention.

As shown in Fig. 14, the structure according to the fifth embodiment is almost the same as the structure of the third or fourth embodiment described above. However, a region for adjusting the upper and lower viewing angles is formed on the opposite side of the region for adjusting the left and right viewing angles.

To further explain the region for adjusting the upper and lower viewing angles, the protrusions 24 of the upper substrate 20 and the protrusions 25 of the lower substrate 10 are formed in the vertical direction, and are alternately arranged in parallel with each other. In addition, the viewing angle adjusting electrode 173 further separated from the pixel electrode of the lower substrate or the common electrode 170 of the upper substrate is further formed. The viewing angle adjusting electrode 173 may be bundled at the same time as the viewing angle adjusting electrode 172 for adjusting the left and right viewing angles or separately.

In the liquid crystal display having such a structure, when voltage is applied to the left and right and / or vertical viewing angle adjustment electrodes 172 and 173, the liquid crystal molecules lie in the vertical and / or horizontal directions, respectively, and thus light leaks in the left and right and / or up and down. . Therefore, the viewing angle in the left and right and / or up and down directions is narrowed. As in the above-described third and fourth embodiments, the viewing angle is adjusted by adjusting the voltage applied to the viewing angle adjusting electrodes 172 and 173 to vary the total voltage applied to the liquid crystal layer, thereby controlling the degree of lying down of the liquid crystal molecules. I can regulate it.

As described above, in the third to fifth embodiments of the present invention, the viewing angle adjustment region is applied to the mode in which the projections for the divided alignment are formed, but the divided patterns are formed by forming the opening patterns on the transparent electrodes of the upper and lower substrates. It can also be applied to the mode. The following sixth and seventh embodiments relate to this.

FIG. 15 is a layout view of a liquid crystal display device having a vertical alignment method according to a sixth embodiment of the present invention, and FIG. 16 is a cross-sectional view taken along line XVI-XVI 'of FIG. 15.

15 and 16, the liquid crystal display according to the sixth exemplary embodiment of the present invention includes a lower substrate as a thin film transistor substrate and an upper substrate as a color filter substrate.

Although not shown in the drawing, the lower substrate 10 has gate lines and data lines intersecting with each other, and an area surrounded by the gate lines and data lines becomes a pixel. One pixel is formed by dividing an opening pattern into two parts, an area for display and an area for adjusting a viewing angle, and a thin film transistor (not shown) for switching pixels is formed in the area for display. The insulating film 31 is covered thereon. The pixel electrode 190 having a plurality of quadrangles connected to the insulating layer 31 is patterned. The area where the pixel electrode 190 is formed becomes an area for display. The viewing angle adjusting electrode 191 is formed in the horizontal direction in the region for adjusting the viewing angle outside the display region.

A black matrix 80 is formed along the edge of the pixel, and a color filter 90 is formed between the black substrates 80 on the upper substrate 20 corresponding to the lower substrate 10. This color filter 90 may be formed in the whole area | region of a pixel, and may be formed only in the area | region for display. In this case, an organic film (not shown) may be formed in the region for adjusting the viewing angle to correct the step instead of the color filter. A protective insulating layer 32 covering the black matrix 80, the color filter 90, and the organic layer covers the entire surface of the substrate, and a transparent common electrode 193 is formed thereon. As illustrated in FIG. 16, the common electrode 193 has cross-shaped openings and straight openings 92 and 91 in cross-sectional and transverse directions, respectively, in a portion corresponding to a region for display and a region corresponding to a region for viewing angle adjustment. Formed. In this case, the opening 91 formed in the region for adjusting the viewing angle may be formed to be thicker than the opening 92 formed in the region for displaying about 10 μm to reduce the texture of the portion.

Vertical alignment layers 180 for vertically aligning the liquid crystal molecules are coated on the surfaces of the electrodes 190, 191, and 193 formed on the upper and lower substrates 20 and 10.

The liquid crystal layer 50 is injected between the substrates 10 and 20. The liquid crystal molecules of the liquid crystal layer 50 are initially aligned vertically between the two substrates 10 and 20 by the alignment force of the vertical alignment layer 180.

Polarizers 1 and 2 are attached to the outer sides of the two substrates 10 and 20, respectively, and the polarization directions P1 and P2 of the two polarizers 1 and 2 are arranged to be perpendicular to each other in the horizontal and vertical directions, respectively. .

Compensation films may be attached between the surfaces of the substrates 10 and 20 and the polarizing plates 1 and 2.

In an embodiment having such a structure, a common voltage is always applied to the common electrode 193 of the upper substrate 20, a voltage for driving a pixel is applied to the pixel electrode 190, and a view angle adjusting electrode 191 is applied to the electrode 191. The voltage is applied according to the required viewing angle mode.

In the case of the display area, when the thin film transistor is in an open state and a data voltage is applied to the pixel electrode 190, the directors of the liquid crystal molecules of the liquid crystal layer 50 have edges of the pixel electrode 190 and the common electrode 193. Since the polarization axes P1 and P2 are arranged at an angle of 45 degrees between the openings 92 of the X-rays, four regions having different orientations are formed.

The overall viewing angle mode of the display device is influenced by the viewing angle of the region for adjusting the viewing angle, and the principle of implementing the wide viewing angle or the narrow viewing angle is almost similar to that in the previous embodiment.

In other words, the voltage is applied to the viewing angle adjusting electrode 191 formed in the region for adjusting the viewing angle of the pixel so that a difference between voltages applied to the pixel electrode 190 and the viewing angle adjusting electrode 171 of the upper substrate 20 does not occur. By applying, the liquid crystal molecules in the region for viewing angle control are arranged perpendicular to the surface of the substrate 10 and 20 in the initial state, so that the region for viewing angle control does not affect the viewing angle of the region for display. Thus, the wide viewing angle mode is maintained.

Meanwhile, when a voltage is applied to the viewing angle adjusting electrode 191 such that a voltage difference between the voltage applied to the pixel electrode 190 and the viewing angle adjusting electrode 191 is generated, a liquid crystal molecule is used in the region for adjusting the viewing angle. Since the inclination of the liquid crystal molecules is inclined in both directions about the opening 91 formed in the viewing angle adjusting electrode 191, the long axes of the liquid crystal molecules are arranged in the vertical direction, which is one of the polarization directions. As described above, since the liquid crystal molecules lie at an angle with respect to the surface of the substrates 10 and 20 and are arranged perpendicular to the polarization axis direction of one of the two polarizing plates 1 and 2, the liquid crystal molecules are perpendicular to the lying direction of the liquid crystal molecules. Light leaks from the right and left direction. In this case, the viewing angle of the area for display is affected, and the left and right viewing angles are narrowed as a whole. The left and right viewing angles become narrower as the difference between the voltages applied to the pixel electrode 190 and the viewing angle adjusting electrode 191 increases.

As such, by appropriately varying the voltage applied to the viewing angle adjusting electrode 191 having the opening 91 drilled in the horizontal direction, a wide viewing angle or a narrow viewing angle may be appropriately implemented in the left and right directions.

The electrode and opening structures for adjusting the viewing angle in the vertical direction as well as the right direction are shown in FIG. 16.

17 is a layout view of a liquid crystal display according to a seventh exemplary embodiment of the present invention.

As shown in FIG. 17, the structure of the liquid crystal display according to the seventh embodiment is almost the same as in the sixth embodiment. However, another viewing angle adjusting electrode 192 extends in the vertical direction from the horizontal viewing angle adjusting electrode 191, and faces the vertical viewing angle adjusting electrode 192 at the common electrode 193 of the upper substrate 20. The opening 93 in the vertical direction is drilled at the viewing position.

If the voltages applied to the viewing angle adjusting electrodes 191 and 192 in the horizontal and vertical directions are adjusted in the same manner as in the previous embodiment, it is possible to narrow the viewing angle in the vertical direction as well as the left and right directions.

Meanwhile, in the first to fifth embodiments of the present invention, the viewing angle adjusting electrode may be formed on both the upper substrate and the lower substrate.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention forms a projection or an opening pattern by separating an area for display and an area for adjusting the viewing angle in one pixel, and forms a pattern of the area for adjusting the viewing angle. By placing the viewing angle adjusting electrode at the opposite position, it is possible to appropriately implement the narrow viewing angle and the wide viewing angle.

Claims (23)

(Correction) the first substrate, A first electrode formed on the first substrate, A second electrode formed on the first substrate, A second substrate corresponding to face the first substrate, A third electrode formed on the second substrate so as to face the first electrode and the second electrode, and A liquid crystal display device comprising a liquid crystal layer injected between the first and second substrates and oriented in a first direction with respect to the first and second substrate surfaces. Image display is realized by the difference in voltage applied between the first electrode and the third electrode, and the line diameter of the liquid crystal layer of the liquid crystal layer is controlled by adjusting the difference in voltage applied between the second electrode and the third electrode. A viewing angle adjusting method of a liquid crystal display device which adjusts a viewing angle by adjusting a blind spot . In claim 1, And the first direction is a direction perpendicular to the surfaces of the first and second substrates. In claim 2, The liquid crystal of the liquid crystal layer has a viewing angle control method of the liquid crystal display device having negative dielectric anisotropy. In claim 1, And adjusting a data voltage and a common voltage to the first electrode and the third electrode, respectively. In claim 1, And adjusting a common voltage and a data voltage to the first electrode and the third electrode, respectively. (Correction) the first substrate, A first common electrode formed on the first substrate and configured to apply a common voltage; A pixel electrode formed on the first substrate to be insulated from the first common electrode, A second substrate corresponding to face the first substrate, A second common electrode formed on the second substrate so as to face the first common electrode and the pixel electrode; and A liquid crystal display device comprising a liquid crystal layer injected between the first and second substrates and oriented in a first direction with respect to the first and second substrate surfaces. And adjusting a viewing angle according to a difference in voltage applied between the first common electrode and the second common electrode. In claim 6, And the first direction is a direction horizontal to the surfaces of the first and second substrates. In claim 7, The liquid crystal of the liquid crystal layer has a viewing angle adjustment method of the liquid crystal display device having a positive dielectric anisotropy. A first substrate having a plurality of pixels each including a display area and a viewing angle adjustment area positioned outside the display area; A first viewing angle adjusting electrode formed on the first substrate and formed in the viewing angle adjusting region of the pixel; A first electrode formed on the first substrate and formed in the display area of the pixel; A second substrate corresponding to face the first substrate, A second electrode formed on the second substrate so as to face the first electrode and the first viewing angle adjusting electrode; A liquid crystal layer injected between the first substrate and the second substrate Liquid crystal display comprising a. In claim 9, And the first electrode and the second electrode are electrodes for applying a data signal voltage and a common signal voltage for driving the pixel, respectively. In claim 9, And the first electrode and the second electrode are electrodes for applying a common signal voltage and a data signal voltage for driving the pixel, respectively. The method of claim 10 or 11, The first viewing angle adjusting electrode is an electrode for variably applying a voltage different from the first or second electrode. In claim 9, A first protrusion pattern formed on the first viewing angle adjusting electrode in a first direction, A first vertical alignment layer coated on the first protrusion pattern; A second projection pattern alternately formed on the second electrode of the viewing angle control region in parallel with the first projection pattern; A second vertical alignment layer coated on the second protrusion pattern, and And first and second polarizing plates attached to outer surfaces of the first and second substrates, and having a polarization axis direction perpendicular to each other, wherein one of the polarization axes has the first direction. In claim 13, A second viewing angle adjusting electrode extending from the first viewing angle adjusting electrode in a second direction perpendicular to the first direction; A third projection pattern formed on the second viewing angle adjusting electrode in the second direction, and And a fourth projection pattern alternately formed in parallel with the third projection pattern on the second electrode of the viewing angle adjustment region. The method of claim 14, The liquid crystal of the liquid crystal layer is a negative dielectric anisotropy liquid crystal display device. In claim 9, A first vertical alignment layer applied on the first electrode and the first viewing angle adjustment electrode, a second vertical alignment layer applied on the second electrode, and an outer surface of the first and second substrates and attached to each other Direction is orthogonal, one of the polarization axes further comprises first and second polarizers having the first direction, And a first opening in the first direction at a position facing the first viewing angle adjusting electrode in the second electrode of the viewing angle adjusting region. The method of claim 16, And a second viewing angle adjusting electrode extending in a second direction perpendicular to the first direction from the first viewing angle adjusting electrode, wherein the second electrode is formed in a second direction at a position facing the second viewing angle adjusting electrode. A liquid crystal display device having a two aperture pattern. The method of claim 17, The liquid crystal display of claim 1, wherein the first and second viewing angle adjusting electrodes are electrically separated from the first electrode and the second electrode to apply a voltage different from the voltage applied to the pixel electrode and the common electrode. (Correct) the first common electrode is formed over the first substrate, An insulating film covering the first common electrode, A plurality of pixel electrodes formed side by side on the insulating film; A second substrate corresponding to face the first substrate, and A second common electrode formed on the second substrate and corresponding to face the first common electrode; Liquid crystal display comprising a. The method of claim 19, The first common electrode is a transparent conductive material formed on the entire surface of the first substrate. The method of claim 19, The first common electrode is formed in plurality in parallel with the pixel electrode. The method of claim 19, And a liquid crystal layer injected between the first and second substrates. The method of claim 22, A voltage separate from the pixel electrode and the first common electrode is applied to the second common electrode, and the liquid crystal of the liquid crystal layer is formed on the first and second substrate surfaces by adjusting a voltage difference from the first common electrode. A liquid crystal display device having a pretilt angle with respect to.