KR101378056B1 - Liquid crystal display device and the method for designing liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for designing the same, and more particularly, to a transflective transverse electric field liquid crystal display device and a method for designing a single cell gap and ensuring a wide viewing angle.

The present invention includes: a first substrate and a second substrate on which a plurality of red, green, and blue pixels in which a transmission region and a reflection region having the same cell gap d are defined are formed; A lower polarizing plate formed under the first substrate; An upper polarizer plate formed on the second substrate and having a transmission axis perpendicular to the transmission axis of the lower polarizer plate; A pixel electrode and a common electrode formed on the first substrate to form a horizontal electric field; A reflection layer formed in the reflection area on the first substrate to reflect light from the outside; A liquid crystal layer formed between the first substrate and the second substrate; A color filter layer comprising red, green, and blue color filters formed on the second substrate so as to correspond to the red, green, and blue pixels on the first substrate; Is achieved by. In addition, a first alignment layer is formed on the first substrate and a second alignment layer is formed on the second substrate, and the reflective region of the red pixel is a third alignment layer on the first substrate. The fourth alignment layer is formed on the second substrate, the reflective region of the green pixel is formed on the first substrate, the fifth alignment layer is formed on the first substrate, and the sixth alignment layer is formed on the second substrate, and the reflective region of the blue pixel is A seventh alignment layer is formed on the first substrate and an eighth alignment layer is formed on the second substrate, and the first alignment layer and the second alignment layer are rubbed so that the liquid crystal in the transmission region is aligned in the same direction as the transmission axis of the lower polarizing plate. Each of the third to eighth alignment layers is arranged such that when the liquid crystal is not driven, the liquid crystal in the reflection region is aligned in a direction in which the reflectance of light corresponding to the color of the color filter formed in the red, green, and blue pixels becomes "0". Otherwise processed rubbing.

Liquid Crystal Display, Transflective, Single Cell Gap

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal display device and a method of designing the liquid crystal display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for designing the same, and more particularly, to a transflective transverse electric field liquid crystal display device and a method for designing a single cell gap and ensuring a wide viewing angle.

Generally, the liquid crystal display device has a tendency of widening its application range due to features such as light weight, thinness, and low power consumption driving. Accordingly, the liquid crystal display device has been widely used as a portable electronic device such as a notebook PC and a mobile phone.

In general, a liquid crystal display device displays a desired image on a screen by controlling a light transmission amount according to a video signal applied to a plurality of switching elements for control arranged in a matrix form.

The liquid crystal display device includes a liquid crystal panel in which a color filter substrate as an upper substrate and a thin film transistor array substrate as a lower substrate face each other and a liquid crystal layer is filled therebetween; And a liquid crystal panel driver for supplying signals and image information to operate the liquid crystal panel.

Since such a liquid crystal display device is a non-light emitting device that can not emit light by itself as compared with a CRT (Cathode-ray Tube) or an LED (Light Emitting Diode), a light source that supplies light to the liquid crystal panel is required to implement an image.

The liquid crystal display device can be roughly divided into two types depending on the type of the light source. That is, the liquid crystal display device is classified into a transmissive liquid crystal display device using a light source provided inside a liquid crystal display device and a reflective liquid crystal display device using an external light source (e.g., solar light).

However, since the transmissive liquid crystal display device uses an internal light source using a portable battery or the like as a power source, high power consumption is required. Therefore, when such a transmissive liquid crystal display device is applied to a portable electronic device, So that the advantage of portability can not be exhibited. In addition, since the reflection type liquid crystal display device uses an external light source such as sunlight, when the light source is used indoors, the intensity of the external light source is weak, so that the brightness of the screen is low.

Therefore, in order to solve the above-described problems, a transflective liquid crystal display device in which a transmissive type and a reflective type are combined has been proposed. Such a transflective liquid crystal display device is easy to apply to a portable electronic device because of low power consumption, and has a merit of being able to observe a high quality screen indoors as well as outdoors.

A transflective liquid crystal display device as described above will now be described with reference to the accompanying drawings.

The conventional liquid crystal display shown in FIG. 1 is a semi-transmissive electrically controlled Birefringence (ECB) liquid crystal display, and includes a first substrate 1 and a second substrate 2 in which transmission and reflection regions are defined. At least one phase compensation plate 16a and 16b including a lower polarizing plate 3 is provided below the first substrate 1, and an upper polarizing plate 4 including at least an upper polarizing plate 4 above the second substrate 2. One phase compensation plate 17a, 17b is provided. A first pixel electrode 5a and a second pixel electrode 5b for applying an electric field to the liquid crystal layer 8 are formed in the transmissive region and the reflective region on the first substrate 1, respectively. Here, the first pixel electrode 5a and the second pixel electrode 5b are electrically connected. A color filter 20 and a common electrode 6 are formed on the second substrate 2. The common electrode 6 is formed on the first substrate 1 and the first and second pixel electrodes 5a, 5b to form an electric field to drive the liquid crystal layer 8.

The first pixel electrode 5a formed in the transmissive region is formed of a transparent conductive material having a relatively high transmittance of light so that the light supplied from the internal light source is easily transmitted to the outside of the liquid crystal display device, The two pixel electrodes 5b are formed of an opaque conductive metal having a relatively high reflectance, so that external light incident from the outside is easily reflected.

In the conventional general transflective ECB liquid crystal display having the structure as described above, the light incident from the external light source passes through the liquid crystal layer 8 twice, and the light reflected from the internal light source passes through the liquid crystal layer. Since the optical characteristic is different because it passes through (8) once, in order to compensate for this, the cell gap (d) of the transmission region has a dual cell gap structure having twice the cell gap (d / 2) of the reflection region. Have

However, in the transflective ECB liquid crystal display device having the above dual cell gap structure, the manufacturing process is not easy due to the step between the transmissive region and the reflective region, which leads to a decrease in productivity.

In the transflective ECB liquid crystal display device as described above, the first and second pixel electrodes 5a and 5b formed on the first substrate 1 and the common electrode 6 formed on the second substrate 2 are perpendicular to each other. Since the liquid crystal is driven by the electric field, the viewing angle is narrow.

Accordingly, an object of the present invention is to provide a transflective transverse electric field liquid crystal display device and a method of designing the same, which can realize a single cell gap and ensure a wide viewing angle. .

According to an exemplary embodiment of the present invention, a liquid crystal display device includes: a first substrate on which a plurality of red, green, and blue pixels, in which a transmission region and a reflection region, having the same cell gap d, are defined; A second substrate; A lower polarizer formed on a lower portion of the first substrate; An upper polarizer plate formed on the second substrate and having a transmission axis perpendicular to the transmission axis of the lower polarizer plate; A pixel electrode and a common electrode formed on the first substrate to form a horizontal electric field; A reflective layer formed on the reflective region on the first substrate and reflecting light from the outside; A liquid crystal layer formed between the first substrate and the second substrate; A color filter layer comprising red, green, and blue color filters formed on the second substrate so as to correspond to the red, green, and blue pixels on the first substrate; . Here, in the transmission region of the red, green, and blue pixels, a first alignment layer is formed on the first substrate and a second alignment layer is formed on the second substrate, and the reflective region of the red pixel is a third alignment layer on the first substrate. The fourth alignment layer is formed on the second substrate, the reflective region of the green pixel is formed on the first substrate, the fifth alignment layer is formed on the first substrate, and the sixth alignment layer is formed on the second substrate, and the reflective region of the blue pixel is formed on the second substrate. A seventh alignment layer is formed on the first substrate, and an eighth alignment layer is formed on the second substrate, and the first alignment layer and the second alignment layer are rubbed to align the liquid crystal in the transmission region in the same direction as the transmission axis of the lower polarizing plate. The third to eighth alignment layers are arranged such that when the liquid crystal is not driven, the liquid crystal in the reflective region is aligned in a direction in which the reflectance of light corresponding to the color of the color filter formed in the red, green, and blue pixels becomes "0". It is subjected to the rubbing treatment.

In addition, a method of designing a liquid crystal display device according to a preferred embodiment of the present invention for achieving the above object includes a plurality of red, green, and blue pixels in which a transmission region and a reflection region having the same cell gap d are defined. A first substrate and a second substrate formed; A lower polarizer formed on a lower portion of the first substrate; An upper polarizer plate formed on the second substrate and having a transmission axis perpendicular to the transmission axis of the lower polarizer plate; A pixel electrode and a common electrode formed on the first substrate to form a horizontal electric field; A reflective layer formed on the reflective region on the first substrate and reflecting light from the outside; A liquid crystal layer formed between the first substrate and the second substrate; A color filter layer comprising red, green, and blue color filters formed on the second substrate so as to correspond to the red, green, and blue pixels on the first substrate; Wherein the liquid crystal formed in the transmission region of the red, green, and blue pixels is oriented in the same direction as the transmission axis of the lower polarizing plate, and the liquid crystal formed in the reflection region of the red, green, and blue pixels has a predetermined twist. CLAIMS What is claimed is: 1. A method of designing a liquid crystal display device oriented so as to be twisted from bottom to top with an angle [theta], comprising: determining a phase difference [Delta] nd of a liquid crystal positioned in a transmission region of the pixel; The color of the color filter of the red, green, and blue pixels when the liquid crystal is not driven with a liquid crystal having a phase difference Δnd equal to the phase difference Δnd of the liquid crystal in the transmission region in the reflection region of the red, green, and blue pixels. Calculate the reflectances R of light corresponding to the respective angles, wherein the angle between the twist angle (θ) of the liquid crystal in the reflection region of each of the red, green, and blue pixels, the alignment direction of the uppermost liquid crystal in the reflection region, and the transmission axis of the upper polarizing plate ( obtaining a light reflectance R for α); In each of the reflective regions of the red, green, and blue pixels, the twist angle (θ) of the liquid crystal in the reflective region where the light reflectance R is "0", the alignment direction of the uppermost liquid crystal in the reflective region, and the transmission axis of the upper polarizing plate are formed. Finding an angle α; .

In the transflective transverse electric field liquid crystal display according to the present invention having the above configuration, the liquid crystal formed in the transmissive region is oriented in the same direction as the transmission axis of the lower polarizing plate, and the liquid crystal formed in the reflective region has a predetermined twist angle (θ). Is oriented so as to be twisted from the lower side to the upper side, and the angle α between the twist angle (θ) of the liquid crystal in the reflective region and the alignment direction of the uppermost liquid crystal in the reflective region and the transmission axis of the upper polarizing plate is not driven. By having a structure set differently within the range that the reflectance of light corresponding to the color of the color filter formed in each pixel becomes "0", it is possible to realize the same cell gap d of the transmission region and the reflection region. . Therefore, the manufacturing process of the liquid crystal display device is advantageous.

In the transflective transverse electric field liquid crystal display according to the present invention having the above-described configuration, in a plurality of pixels displaying different colors, the transflective area of the reflective region considering the wavelength value of light corresponding to the color displayed by the pixel is considered. The contrast ratio can be improved by forming different angles? Between the twist angle θ of the liquid crystal and the alignment direction of the uppermost liquid crystal in the reflection region and the transmission axis of the upper polarizing plate for each pixel.

The transflective transverse electric field liquid crystal display device according to the present invention having the above structure has the effect of securing a wide viewing angle since the liquid crystal is driven by the electric field formed by the pixel electrode and the common electrode provided on the first substrate .

Hereinafter, a liquid crystal display device and a method of designing the same according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the structure of a liquid crystal display device according to a preferred embodiment of the present invention will be described.

As shown in FIG. 2 and FIG. 3, a liquid crystal display according to an exemplary embodiment of the present invention includes a plurality of red, green, and blue pixels P _R , in which a transmission region and a reflection region having the same cell gap d are defined. A first substrate 101 and a second substrate 102 on which P _G and P _B are formed; A lower polarizing plate 103 formed below the first substrate 101; An upper polarizing plate 104 formed on an upper portion of the second substrate 102 and having a transmission axis perpendicular to the transmission axis of the lower polarizing plate 103; A pixel electrode 105 and a common electrode 106 formed on the first substrate 101 to form a horizontal electric field; A reflection layer 107 formed in a reflection area on the first substrate 101 to reflect light from the outside; A liquid crystal layer 108 formed between the first substrate 101 and the second substrate 102; Red, green, and blue color filters 109a, 109b, and 109c formed on the second substrate 102 to correspond to the red, green, and blue pixels P _R , P _G , and P _B on the first substrate 101. A color filter layer 109; .

Here, in the transmission regions of the red, green, and blue pixels P _R , P _G , and P _B , a first alignment layer 115 is formed on the first substrate 101, and a second alignment layer is formed on the second substrate 102. 116 is formed, and in the reflective region of the red pixel P _R , a third alignment layer 117 is formed on the first substrate 101, and a fourth alignment layer 118 is formed on the second substrate 102. In the reflective region of the green pixel P _G , the fifth alignment layer 119 is formed on the first substrate 101, and the sixth alignment layer 120 is formed on the second substrate 102. In the reflective region of P _B ), a seventh alignment layer 121 is formed on the first substrate 101, an eighth alignment layer 122 is formed on the second substrate 102, and the first alignment layer 115 is formed. The second alignment layer 116 is rubbed so that the liquid crystal in the transmission region is aligned in the same direction as the transmission axis of the lower polarizing plate 103, and the third to eighth alignment layers 117 to 122 reflect when the liquid crystal is not driven. The liquid crystal in the area is red, green, The rubbing process is performed differently so that the reflectance of light corresponding to the color of the color filter 109 formed in the blue pixels P _R , P _G , and P _B is oriented in a direction of becoming “0”.

Hereinafter, each component of the liquid crystal display according to the preferred embodiment of the present invention having the above configuration will be described in detail.

Referring to FIG. 3, the LCD includes a first substrate 101 that is a thin film transistor array substrate and a second substrate 102 that is a color filter substrate, and a liquid crystal layer 108 is formed between the two substrates. do.

A lower polarizer 103 is provided on the lower portion of the first substrate 101 and an upper polarizer 104 is provided on the upper portion of the second substrate 102. The transmissivity of the two polarizers 103 and 104 The axes are 90 ° apart from each other.

Referring to FIG. 2, the gate line 110 and the data line 111 cross vertically and horizontally on the first substrate 101 to define a plurality of red, green, and blue pixels P _R , P _G , and P _B. Each pixel P _R , P _G , and P _B defines a transmission area and a reflection area having the same cell gap d. The thin film transistor 112 is formed at a point where the gate line 110 and the data line 111 of each pixel P _R , P _G , and P _B cross each other.

Each pixel includes a pixel electrode 105 and a common electrode 106 that are alternately spaced apart from each other by a predetermined interval, and the pixel electrode 105 includes a thin film transistor formed in the corresponding pixels P _R , P _G , and P _B. It is connected to the drain electrode 112a of 112, and the common electrode 106 is connected to the common voltage line 113.

Referring to FIGS. 2 and 3, a reflection layer 107 for reflecting external light incident from the outside is formed in the reflection region of the first substrate 101. The reflective layer 107 may be formed in an embossed shape consisting of a plurality of curved surfaces in order to increase the reflection efficiency of light.

Referring to FIG. 3, any one of red, green, and blue color filters 109a, 109b, and 109c is applied to each of the red, green, and blue pixels P _R , P _G , and P _B on the second substrate 102. A color filter layer 109 is formed to correspond to each other, and although not shown in the drawing, a boundary between each pixel P _R , P _G , and P _{B on which} the red, green, and blue color filters 109a, 109b, and 109c are formed is provided. Black matrix is formed.

Here, the color filters 109a, 109b, and 109c positioned in the reflective region may provide holes at predetermined intervals, as shown in FIG. 3, which is after the light generated from the external light source enters the reflective layer 107. This is to minimize the amount lost due to the color filters 109a, 109b, and 109c while being reflected and emitted to the outside.

Referring to FIG. 3, rubbing in the same direction as the transmission axis of the lower planar plate 103 is performed in the transmission region of the red and green blue pixels P _R , P _G , and P _B formed on the first substrate 101. A first alignment layer 115 is formed, and in the transmission region of the red, green, and blue pixels P _R , P _G , and P _B formed on the second substrate 102 in the same direction as the transmission axis of the lower polarizing plate 103. The rubbed second alignment layer 116 is formed.

In addition, a fourth alignment layer 118 rubbed in a direction having a predetermined angle with a transmission axis of the upper polarizing plate 104 is formed in the reflective region of the red pixel P _R formed on the second substrate 102. A third alignment layer 117, which is rubbed in a direction having a predetermined angle with a rubbing direction of the fourth alignment layer 118, is formed in the reflective region of the red pixel P _R formed on the first substrate 101, and the second substrate is formed. A sixth alignment layer 120 rubbed in a direction having a predetermined angle with the transmission axis of the upper polarizing plate 104 is formed in the reflective region of the green pixel P _G formed in the 102, and the first substrate 101 is formed. A fifth alignment layer 119, which is rubbed in a direction having a predetermined angle with a rubbing direction of the sixth alignment layer 120, is formed in the reflective region of the green pixel P _G formed in the blue pixel P _G , and is formed on the second substrate 102. the reflection area of the pixel (P _B) is having a transmission axis and a predetermined angle of the upper polarizing plate 104 The eighth alignment film 122 is rubbed in a direction are formed, wherein, the reflection area of the blue pixel (P _B) formed on the second substrate 102 is rubbed in a direction having a rubbing direction and a predetermined angle of the eighth alignment film 122 Formed seventh alignment layer 121 is formed.

Therefore, the liquid crystal formed in the transmission region is oriented in the same direction as each of the pixels P _R , P _G , and P _{B in the} same direction as the transmission axis of the lower polarizing plate 103, and the liquid crystal formed in the reflection region has a predetermined twist angle ( each pixel, ie, red, green, and blue pixels P _R , P _G , P _B so as to be twisted from bottom to top with θ).

Here, the angle formed by the twist angle θ of the liquid crystal formed in each of the reflection regions of the red, green, and blue pixels P _R , P _G , and P _B , the alignment direction of the uppermost liquid crystal in the reflection region, and the transmission axis of the upper polarizing plate ( α) is differently set within the range where the reflectance of light having a wavelength corresponding to the color of the color filters 109a, 109b, and 109c formed in each pixel when the liquid crystal is not driven becomes "0". It will be described in detail as follows.

Since the direction in which the liquid crystal in the transmissive region is aligned with the transmissive axis of the upper polarizer 104 is such that the transmissive region is black when the liquid crystal is not driven. Therefore, when the liquid crystal of the reflective region is also not driven, black must be implemented as in the transmissive region. Thus, in order for the reflective region to realize black, the reflectance of light incident from the outside must be "0". In other words, both the transmission region and the reflection region should be in a normally black mode.

Accordingly, the liquid crystal may not be driven in the reflection regions of the red, green, and blue pixels P _R , P _G , and P _B in consideration of the wavelength of the color displayed by the pixels P _R , P _G , and P _B. So that the light reflectance of the reflection regions of all the pixels P _R , P _G , P _B is "0", that is, the reflection regions of all the pixels P _R , P _G , P _B implement the normally black mode. It is designed to. This is because the respective pixels (P _R, P _G, P _B) the reflection region pixels (P _R, P _G, P _B) but they are not designed differently depending on the color wavelength of the display pixels (P _R a, In the case where all of the reflection areas of P _G and P _B are designed to have the same condition, the reflection area of each pixel P _R , P _G and P _B has a different light reflectance depending on the wavelength of light of the color it displays. This is because normal black modes such as a transmission region cannot be realized.

As described above, when the light reflectance of the reflection areas of the red, green, and blue pixels P _R , P _G , and P _B becomes "0", the red, green, and blue pixels P _R , P _G , P _B of The twist angle (θ) of the liquid crystal of each of the reflection regions and the angle (α) formed between the alignment direction of the uppermost liquid crystal of the reflection region and the transmission axis of the upper polarizer are determined with respect to the light reflectance R obtained by using the Jones's matrix. The light reflectance R of each of the reflective regions of the red, green, and blue pixels P _R , P _G , and P _B may be obtained by the following Equation 1 below.

In Equation (1),? Is an angle formed by the alignment direction of the uppermost liquid crystal in the reflection region and the transmission axis of the upper polarizer 104, and H and M are expressed by the following equations (2) and (3).

In Equation (2),? Is the twist angle of the liquid crystal in the reflective region, and A, B, C, and D are the following Equations 4, 5, 6, In addition, i is an imaginary unit and i ^ 2 = -1.

D is the thickness of the liquid crystal cell in the reflective region,? N is the refractive index anisotropy of the liquid crystal,? D and k _a Is expressed by the following equations (8) and (9).

In the above equation, λ is a wavelength of light corresponding to a color displayed by the red and green blue pixels P _R , P _G , and P _B.

After determining a predetermined value within a range of a phase difference Δnd of a liquid crystal suitable for the transmission region of the pixels P _R , P _G , and P _B , the red, green, and blue pixels P _R , P _G , P _B The reflectance R of light corresponding to the wavelength λ of the color indicated by is obtained by applying the above-mentioned formulas (1) to (9). Here, the range of the retardation (Δnd) of a suitable liquid crystal in the transmissive region of the pixel (P _R, P _G, P _B) is 275㎚≤Δnd≤380㎚.

That is, red and green to which a liquid crystal having a phase difference Δnd equal to the wavelength λ of light corresponding to the color displayed by the pixels P _R , P _G , and P _B itself and the phase difference Δnd of the liquid crystal in the transmission region is applied. The light reflectance R of each of the reflection regions of the blue pixels P _R , P _G , and P _B is obtained by applying the equations (1) to (9). Here, the light reflectance R of the reflection region of each of the pixels P _R , P _G , and P _B is a value when the liquid crystal is not driven.

As described above, the phase difference Δnd of the liquid crystal in the reflection region and the wavelength λ of light corresponding to the color displayed by each pixel P _R , P _G , and P _B are obtained by applying the following equations (1) to (9). the top of the reflective area of the red, green and blue pixels (P _R, P _G, P _B) twist angle (θ) and the red, green and blue pixels (P _R, P _G, P _B) of the liquid crystal in the reflection region of the liquid crystal By applying an angle α formed between the alignment direction of the upper polarizing plate and the transmission axis of the upper polarizing plate, a transflective transverse electric field liquid crystal display device having the same cell gap d between the transmission area and the reflection area may be implemented.

Hereinafter, in the liquid crystal display according to the preferred embodiment of the present invention having the above structure, the red, green, and blue pixels P _R , P _G , and P _B capable of realizing a single cell gap between the transmission area and the reflection area may be used. A method of designing the angle? Between the twist angle? Of the liquid crystal in the reflection region, the alignment direction of the uppermost liquid crystal in the reflection region, and the transmission axis of the upper polarizing plate 104 will be described with specific examples.

First, a predetermined value is determined within a range of phase difference Δnd of a liquid crystal suitable for a transmission region of pixels P _R , P _G , and P _B defined in the first substrate 101 and the second substrate 102. Here, the range of the phase difference Δnd of the liquid crystal suitable for the transmission region of the pixels P _R , P _G , and P _B is 275 nm ≦ Δnd ≦ 380 nm, and for the purpose of understanding the present invention, the phase difference of the transmission region ( Δnd) will be arbitrarily determined to be 275 nm in the above range.

Then, in each of the reflection regions of the red, green, and blue pixels P _R , P _G , and P _B , the liquid crystal is not driven with the phase difference Δnd equal to the phase difference Δnd of the liquid crystal in the transmission region. The graph of the reflectance R of light corresponding to the color of the color filters 109a, 109b, and 109c of each pixel at the time is obtained.

In this case, the graph of the light reflectance (R) is a graph showing the light reflectance (R) of the red, green, blue pixels (P _R , P _G , P _B ) when the liquid crystal is not driven.

In more detail, the graph of the light reflectance (R) is an angle formed by the twist angle (θ) of the liquid crystal in the reflection region and the alignment direction of the uppermost liquid crystal in the reflection region and the transmission axis of the upper polarizing plate 103 when the liquid crystal is not driven. It is a graph which shows the reflectance R of the light with respect to (alpha), and the graph about the reflectance R of this light is as FIG. 4A-FIG. 4C.

For reference, FIGS. 4A to 4C show that the liquid crystals of the transmission region and the reflection region of the red, green, and blue pixels P _R , P _G , and P _B all have a phase difference Δnd of 275 nm, but the liquid crystal is not driven. FIG. 4A is a graph showing the light reflectance R with respect to the angle α between the twist angle θ of the liquid crystal in the reflective region and the alignment direction of the uppermost liquid crystal in the reflective region and the transmission axis of the upper polarizing plate 104. Is a graph showing the light reflectance (R) with respect to the reflection area of the red pixel (P _R ), Figure 4b is a graph showing the light reflectance (R) for the reflection area of the green pixel (P _G ), Figure 4c (P _B ) It is a graph showing the reflectance R of light with respect to the reflecting region of the pixel.

Next, the twist angle θ of the liquid crystal in the reflection regions of the red, green, and blue pixels P _R , P _G , and P _B , the alignment direction of the uppermost liquid crystal in the reflection region, and the transmission axis of the upper polarizing plate 104 are formed. Reflection in which the light reflectance R becomes "0" in the reflection regions of the red, green, and blue pixels P _R , P _G , and P _B with reference to the graph of the light reflectance R with respect to the angle α. The angle α between the twist angle θ of the liquid crystal in the region and the alignment direction of the uppermost liquid crystal in the reflective region and the transmission axis of the upper polarizing plate 104 is found.

In FIG. 4A to FIG. 4C, a portion relatively close to white represents a portion having a high light transmittance R, and a portion relatively close to black represents a portion having a low light transmittance R. Referring to FIG. Therefore, it can be seen that the part indicated by black is the case where the light transmittance R is "0".

That is, referring to FIG. 4A, when the liquid crystal is not driven, the reflection area of the red pixel P _R has a twist angle θ of 71 ° and the alignment direction of the uppermost liquid crystal of the reflection area and the upper polarizing plate 104. It can be seen that the light reflectance R becomes "0" when the angle α formed by the transmission axis of is 10 °.

4B, the reflection region of the green pixel P _G has a twist angle θ of 72 ° when the liquid crystal is not driven, the alignment direction of the uppermost liquid crystal in the reflection region, and the upper polarizer 104. It can be seen that the light reflectance R becomes "0" when the angle α formed by the transmission axis of is 18.5 °.

4C, when the liquid crystal is not driven, the reflection area of the blue pixel P _B has a twist angle θ of 61 ° and the alignment direction of the uppermost liquid crystal of the reflection area and the upper polarizing plate 104. It can be seen that the light reflectance R becomes "0" when the angle α formed by the transmission axis of is 28 °.

That is, when the phase difference Δnd of the liquid crystal in the transmission region of the red, green, and blue pixels P _R , P _G , and P _B is 275 nm, and the phase difference Δnd of the liquid crystal in the reflection region is also 275 nm, red and green. The reflection regions of the blue pixels P _R , P _G , and P _B each have a twist angle θ of the liquid crystal and an angle α formed by the alignment direction of the uppermost liquid crystal of the reflection region and the transmission axis of the upper polarizing plate 104. It can be seen that as mentioned above.

In addition, other examples are shown in FIGS. 5A to 5C to assist in understanding the present invention. 5A to 5C show that the liquid crystals in the transmission region and the reflection region of the red, green, and blue pixels P _R , P _G , and P _B all have a phase difference Δnd of 340 nm, but are not reflected when the liquid crystal is not driven. It is a graph which shows the reflectance R of the light with respect to the angle (alpha) which the twist angle (theta) of the liquid crystal of an area | region and the orientation direction of the uppermost liquid crystal of a reflection area, and the transmission axis of the upper polarizing plate 104 make, and FIG. 5A-FIG. 5C Each is a graph showing the light reflectances R with respect to the reflection areas of the red, green, and blue pixels P _R , P _G , and P _B , respectively.

5A to 5C, the phase difference Δnd of the liquid crystal in the transmission region of the red, green, and blue pixels P _R , P _G , and P _B is 340 nm, and the phase difference Δnd of the liquid crystal in the reflection region is also 340. In the case of nm, the reflection region of the red pixel P _R has a twist angle θ of 71 degrees when the liquid crystal is not driven and the alignment direction of the uppermost liquid crystal of the reflection region and the transmission axis of the upper polarizing plate 104. When the angle α is 20.5 °, the light reflectance R becomes “0”, and the reflection region of the green pixel P _G has a twist angle θ of 60 when the liquid crystal is not driven. When the angle α between the alignment direction of the uppermost liquid crystal in the reflection region and the transmission axis of the upper polarizing plate 104 is 28.5 °, the light reflectance R becomes "0", and the blue pixel P _B When the liquid crystal is not driven, the reflection region has a twist angle θ of 0 °, and an alignment direction of the uppermost liquid crystal in the reflection region and the transmission axis of the upper polarizing plate 104. (Α) a light reflection factor (R) in the case of the 45 ° it can be seen that this "0".

The angle formed by the phase difference (Δnd) of the liquid crystal, the twist angle (θ) of the liquid crystal and the alignment direction of the uppermost liquid crystal in the reflection region and the transmission axis of the upper polarizing plate 104 are designed through the design procedure as described in detail, for example. When (α) is applied, the transmission region and the reflection region of the red, green, and blue pixels P _R , P _G , and P _B are both "0" when the liquid crystal is not driven, and thus the black region is black. When the liquid crystal is driven, the light transmittance and the light reflectance will gradually increase to implement white.

That is, in the liquid crystal display device designed using the design method according to the present invention, the transmission region and the reflection region of the red, green, and blue pixels P _R , P _G , and P _B realize black when the liquid crystal is not driven, When driven, it reliably implements normally black, which implements white.

The angle formed by the phase difference Δnd, the twist angle θ of the liquid crystal, the alignment direction of the uppermost liquid crystal in the reflection region, and the transmission axis of the upper polarizing plate 104 are designed through the design sequence as specifically described above. When (α) is applied to the liquid crystal display, a transflective transverse electric field mode having a single cell gap structure having the same cell gap d in the transmissive region and the reflective region can be implemented.

1 is a cross-sectional view showing a conventional general ECB transflective liquid crystal display device.

2 is a plan view of a liquid crystal display according to a preferred embodiment of the present invention.

3 is a cross-sectional view taken along the lines II ′ and II-II ′ and III-III ′ of FIG. 1.

4A to 4B illustrate the twist angle θ of the liquid crystal in the reflection region and the alignment direction of the uppermost liquid crystal in the reflection region and the transmission of the upper polarizing plate when the liquid crystal of the pixels displaying red, green, and blue in FIG. 2 is not driven. As an example of the graph showing the light reflectance R according to the angle α of the axis, the light reflectance of the reflection region when the phase difference Δnd of the liquid crystal of the transmission region and the reflection region of each pixel is 275 nm ( 4A to 4C are graphs showing light reflectances (R) with respect to reflection regions of pixels displaying red, green, and blue colors, respectively.

5A to 5B illustrate a twist angle (θ) of the liquid crystal in the reflection region and an alignment direction of the upper liquid crystal in the reflection region and the upper polarizing plate when the liquid crystal of each pixel displaying red, green, and blue in FIG. 2 is not driven. As an example of a graph showing the light reflectance R according to the angle α formed by the transmission axis, the light reflectance of the reflection region when the phase difference Δnd of the liquid crystal of the transmission region and the reflection region of each pixel is 340 nm. 5A to 5C are graphs showing light reflectances R with respect to reflective regions of pixels displaying red, green, and blue colors, respectively.

DESCRIPTION OF REFERENCE NUMERALS

101: first substrate 102: second substrate

103: lower polarizing plate 104: upper polarizing plate

105: pixel electrode 106: common electrode

107: reflective layer 109: color filter

110: gate line 111: data line

112: thin film transistor 113: common voltage line

115 to 122: first to eighth alignment films

Claims (6)

A first substrate and a second substrate having a plurality of red, green, and blue pixels in which a transmission region and a reflection region having the same cell gap d are defined; A lower polarizer formed on a lower portion of the first substrate; An upper polarizer plate formed on the second substrate and having a transmission axis perpendicular to the transmission axis of the lower polarizer plate; A pixel electrode and a common electrode formed on the first substrate to form a horizontal electric field; A reflective layer formed on the reflective region on the first substrate and reflecting light from the outside; A liquid crystal layer formed between the first substrate and the second substrate; A color filter layer comprising red, green, and blue color filters formed on the second substrate so as to correspond to the red, green, and blue pixels on the first substrate; And, In the transmission region of the red, green, and blue pixels, a first alignment layer is formed on a first substrate and a second alignment layer is formed on a second substrate. In the reflective region of the red pixel, a third alignment layer is formed on the first substrate and the fourth alignment layer is formed on the second substrate, and the reflective region of the green pixel is formed on the first substrate and the fifth alignment layer is formed on the second substrate. A sixth alignment layer is formed on the reflective region of the blue pixel, a seventh alignment layer is formed on the first substrate, and an eighth alignment layer is formed on the second substrate, The first alignment layer and the second alignment layer are rubbed to align the liquid crystal in the transmission region in the same direction as the transmission axis of the lower polarizing plate, Each of the third to eighth alignment layers is rubbed differently so that the liquid crystals in the reflective region are aligned in a direction in which the reflectance of light corresponding to the color of the color filter formed in the red, green, and blue pixels becomes "0" when the liquid crystal is not driven. Liquid crystal display device characterized in that. The light reflectance R of each of the reflective regions of the red, green, and blue pixels is expressed by using a Jones's matrix.

Of the liquid crystal display panel. (here,

Lt;

Lt;

Θ is the twist angle of the liquid crystal in the reflection region, α is the angle formed between the alignment direction of the uppermost liquid crystal of the reflection region and the transmission axis of the upper polarizing plate, Δn is the refractive index anisotropy of the liquid crystal, d is the first substrate and the second Is the cell gap between the substrates, and λ is the wavelength of light corresponding to the color of the color filter formed in the pixel, i is an imaginary unit, i ^ 2 = -1.) The color filter of claim 1, wherein each of the red, green, and blue color filters is further provided with holes for minimizing light loss due to the red, green, and blue color filters. LCD display device. A first substrate and a second substrate having a plurality of red, green, and blue pixels in which a transmission region and a reflection region having the same cell gap d are defined; A lower polarizer formed on a lower portion of the first substrate; An upper polarizer plate formed on the second substrate and having a transmission axis perpendicular to the transmission axis of the lower polarizer plate; A pixel electrode and a common electrode formed on the first substrate to form a horizontal electric field; A reflective layer formed on the reflective region on the first substrate and reflecting light from the outside; A liquid crystal layer formed between the first substrate and the second substrate; A color filter layer comprising red, green, and blue color filters formed on the second substrate so as to correspond to the red, green, and blue pixels on the first substrate; Wherein the liquid crystal formed in the transmission region of the red, green, and blue pixels is oriented in the same direction as the transmission axis of the lower polarizing plate, and the liquid crystal formed in the reflection region of the red, green, and blue pixels has a predetermined twist. A design method of a liquid crystal display device oriented so as to be twisted from bottom to top with an angle θ, Determining a phase difference Δnd of the liquid crystal positioned in the transmission region of the pixel; The color of the color filter of the red, green, and blue pixels when the liquid crystal is not driven with the liquid crystal having a phase difference Δnd equal to the phase difference Δnd of the liquid crystal in the transmission region in the reflection region of the red, green, and blue pixels. The reflectance R of the light corresponding to each of the light beams is calculated, and the angle between the twist angle (θ) of the liquid crystal in the reflection region of each of the red, green, and blue pixels, the alignment direction of the uppermost liquid crystal in the reflection region, and the transmission axis of the upper polarizing plate ( obtaining a light reflectance R for α); In each of the red, green, and blue pixel reflecting regions, the angle between the twist angle (θ) of the liquid crystal in the reflecting region where the light reflectance R is "0", the alignment direction of the uppermost liquid crystal in the reflecting region, and the transmission axis of the upper polarizing plate finding (α); Design method of a liquid crystal display device comprising a. The light reflectance R of each of the reflective regions of the red, green, and blue pixels is expressed by using a Jones's matrix.

Of the liquid crystal display device. (here,

Lt;

Lt;

Δn is the refractive index anisotropy of the liquid crystal, d is the cell gap between the first substrate and the second substrate, λ is the wavelength of light corresponding to the color of the color filter formed in the pixel, i is an imaginary unit, i ^ 2 = -1.) The method of designing a liquid crystal display device according to claim 4, wherein the range of the phase difference [Delta] nd of the liquid crystal located in the transmission region and the reflection region of the red, green, and blue pixels is 275 nm≤Δnd≤380 nm.

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