KR100356835B1 - Reflective liquid crystal display device - Google Patents

Abstract

The present invention discloses a reflective liquid crystal display device which achieves high transmittance without having additional optical components such as quarter wave plate, reflector plate and scattering plate. The present invention discloses an upper and lower substrate facing each other at a predetermined distance; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; A counter electrode and a pixel electrode disposed on an inner side of the lower substrate and forming a fringe electric field for operating the liquid crystal molecules; A polarizer disposed on an outer surface of the upper substrate and having a predetermined polarization axis; And first and second alignment layers disposed on inner surfaces of the upper and lower substrates, respectively, and having a predetermined rubbing axis, wherein the counter electrode and the pixel electrode are formed of a highly reflective metal film, and the rubbing axis of the first alignment layer is When the dielectric anisotropy of the liquid crystal molecules is negative with respect to the direction in which the fringe electric field is formed, the angle difference is about 0 to 45 degrees, and when the dielectric anisotropy of the liquid crystal molecules is positive, the angle difference is about 45 to 90 degrees. The molecule is characterized in that its retardation (r) value is (2n + 1) λ / 4, and n is an integer.

Description

Reflective Liquid Crystal Display {REFLECTIVE LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal display device, and more particularly, to a reflective liquid crystal display device having a high transmittance without the provision of a reflective plate and a quarter wave plate.

In general, the reflective LCD does not require a separate light source such as a backlight, and natural light is used as the light source.

The general principle of such a reflective LCD is that when natural light is incident from the upper substrate, light is reflected again through the reflecting plate disposed on the bottom surface of the lower substrate. At this time, the light is absorbed, reflected or passed according to the arrangement state of the liquid crystal molecules.

The commonly used reflective TN (twist nematic) LCD has a very narrow viewing angle, so that a full color can be realized in the conventional reflective mode, and the reflective hybrid mode has a fast response speed even at low voltage. Was proposed. However, since the reflective hybrid mode LCD uses only the birefringence effect of the liquid crystal molecules, gray scale inversion is easily generated depending on the viewing direction, and the contrast ratio is lowered. In addition, although the biaxial compensation film was used to compensate for the viewing angle along the viewing direction, the biaxial compensation film was difficult to manufacture itself, which caused a problem that was difficult to apply to the cell.

Therefore, in the related art, in order to obtain a wide viewing angle while solving the problem of gray level inversion without an optical compensation film, a Korean LCD application 97-67776 has proposed a new concept reflective LCD.

1A and 1B, the reflective LCD includes a lower substrate 11, an upper substrate 12 facing the lower substrate, a pixel electrode 13 formed in a stripe shape on the upper surface of the lower substrate 11, The counter electrode 14 spaced a predetermined distance from the pixel electrode 13 in the same plane as the pixel electrode 13, the first vertical alignment layer 19 coated on the upper substrate, the pixel electrode 13, and the counter electrode 14. The second vertical alignment layer 20 covering the upper surface of the formed lower substrate 11 and the liquid crystal layer 15 formed between the first and second vertical alignment layers. Here, although not shown in the figure, the inner surface of the upper substrate 12 is provided with a color filter.

In addition, the reflective liquid crystal display device includes a reflecting plate 16 disposed on the rear surface of the lower substrate 11, a polarizing plate 18 disposed on the rear surface of the upper substrate, and a half wave plate disposed between the upper substrate 12 and the polarizing plate 18. (17) is further provided. Here, the liquid crystal having positive dielectric anisotropy was used as the liquid crystal layer 15. The polarizing plate is arranged so that its polarization axis is 45 degrees with the direction of the electric field, and the half wave plate 17 is arranged so that its axis is 45 degrees with the polarizing axis of the polarizing plate 18. Here, the pixel electrode 13 and the counter electrode 14 are formed of an opaque metal film such as aluminum, chromium or the like.

Referring to the operation of the reflective liquid crystal display device, when no voltage is applied, as shown in FIGS. 1A and 2A, all of the liquid crystal molecules 15a of the liquid crystal layer 15 may be affected by the vertical alignment layers 19 and 20. The long axis is arranged perpendicular to the top substrate 12 and bottom substrate 11 surfaces. Only components in a predetermined direction among the unpolarized light sources pass through the polarizing plate 18 and are linearly polarized to the right (or left). When the light passing through the polarizing plate 18 passes through the quarter wave plate 17, it is left circularly polarized (or right circularly polarized). Since all liquid crystal molecules 15a of the liquid crystal layer 15 are arranged in the Z direction, the light passing through the quarter-wave plate 17 passes through the liquid crystal layer 15 without a phase change. Since the traveling direction of the light reflected by the reflector 16 changes to -Z, the left circularly polarized light (or right circularly polarized light) before the reflection is right circularly polarized (or left circularly polarized light). )do. The right circularly polarized light (or left circularly polarized light) passes through the liquid crystal layer 15 as it is and enters into the quarter-wave plate 17 again. The light passing through the quarter wave plate 17 is linearly polarized on the left (or right). However, since the axis of the light passing through the polarizing plate 18 and the axis of the light incident on the polarizing plate 18 are vertical, the light incident from the quarter wave plate 17 into the polarizing plate 18 does not pass through the polarizing plate 18. That is, it shows a dark state.

On the other hand, when voltage is applied, as shown in FIGS. 1B and 2B, liquid crystals directly contacting the substrate surface under the influence of the vertical alignment layers 19 and 20 maintain a state in which no voltage is applied. In the central portions of the pixel electrode 13 and the counter electrode 14, the long axes of the liquid crystals are arranged perpendicularly to the upper substrate 12 and the lower substrate 11 surfaces, such as portions in contact with the substrate. Since a horizontal electric field E _A and an elliptical fringe electric field E _B are formed between the pixel electrode 13 and the counter electrode 14, liquid crystal molecules are arranged along the electric fields E ₁ and E ₂ . Thus, except for the portion in contact with the substrate, two domains which are symmetrical about the center lines of the pixel electrode 13 and the counter electrode 14 are formed.

Looking at the progress of the light, only a component in a predetermined direction of the light source that is not polarized passes through the polarizing plate 18 and is linearly polarized. Upon passing through the quarter-wave plate 17, the light changes to left circularly polarized (or right circularly polarized). The polarization state is changed by the angle between the optical axis of the liquid crystal molecules and the transmission axis of the quarter wave plate 17 while passing through the liquid crystal layer 15. That is, the left circularly polarized light linearly polarizes to the left (or right) while passing through the liquid crystal layer 15. The light reflected by the reflector 16 is linearly polarized right (or left). The right (or left) linearly polarized light passes through the liquid crystal layer 15 and is left (or right) circularly polarized. After that, it enters into the quarter wave plate 17. The light passing through the quarter wave plate 17 is linearly polarized right (or left). As a result, the axis of light passing through the polarizing plate 18 and the axis of light incident from the quarter wave plate 17 into the polarizing plate 18 are parallel, so that the light passes through the polarizing plate 18. That is, it forms a white state.

However, since the conventional reflective liquid crystal display uses natural light instead of a backlight as a light source, additional components such as the scattering plate and the reflecting plate are additionally required, although not mentioned in the quarter wave plate 17 and the prior art. . This increases the manufacturing cost.

In addition, the above-described reflective liquid crystal display device drives the transverse electric field, and thus has a lower transmittance (reflectance) than the conventional twisted nematic liquid crystal display device.

As a result, the luminance is lowered, resulting in a problem of poor image quality.

In addition, the reflection type liquid crystal display device uses the color filter used in the conventional transmission type liquid crystal display device, which is difficult to use the light efficiently because the absorption of the color filter is severe.

Accordingly, it is an object of the present invention to provide a reflective liquid crystal display device which can operate in a reflective type without having additional optical components such as quarter wave plate, reflector plate and scattering plate.

In addition, another object of the present invention is to provide a reflective liquid crystal display device capable of improving the transmittance (reflectance) by operating all of the liquid crystal molecules present on the upper surface of the electrode.

1A and 1B are cross-sectional views of a conventional reflective liquid crystal display device.

2A and 2B are diagrams for explaining a path of light propagation in a conventional reflective liquid crystal display device;

3 is a perspective view of a reflective liquid crystal display device according to the present invention;

4 is a plan view of a liquid crystal display according to the present invention;

5 is a plan view of a liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 6 is a view for explaining a propagation path of light in an off-white reflective liquid crystal display device according to the present invention; FIG.

7 is a cross-sectional view of a reflective liquid crystal display device according to the present invention;

8A to 8C are diagrams for explaining a propagation path of light on on of a reflection type liquid crystal display device of a normally white mode according to the present invention;

(Explanation of symbols for the main parts of the drawing)

40: lower substrate 41a, 41b: gate bus line

42 common signal line 43430 counter electrode

44 gate insulating film 45 channel layer

46: pixel electrodes 47a, 47b: data bus lines

48: drain electrode 49: source electrode

50 thin film transistor 60 upper substrate

53: first alignment layer 63: second alignment layer

70: polarizer

In order to achieve the above object of the present invention, according to an embodiment of the present invention, the upper and lower substrates facing a predetermined distance; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; A counter electrode and a pixel electrode disposed on an inner side of the lower substrate and forming a fringe electric field for operating the liquid crystal molecules; A polarizer disposed on an outer surface of the upper substrate and having a predetermined polarization axis; And first and second alignment layers disposed on inner surfaces of the upper and lower substrates, respectively, and having a predetermined rubbing axis, wherein the counter electrode and the pixel electrode are formed of a highly reflective metal film, and the rubbing axis of the first alignment layer is When the dielectric anisotropy of the liquid crystal molecules is negative with respect to the direction in which the fringe electric field is formed, the angle difference is about 0 to 45 degrees, and when the dielectric anisotropy of the liquid crystal molecules is positive, the angle difference is about 45 to 90 degrees. The molecule is characterized in that its retardation (r) value is (2n + 1) λ / 4, and n is an integer.

The counter electrode and the pixel electrode are formed of one metal film selected from Ag, Al, and MgO.

The counter electrode may include a plurality of branches, a body portion connecting one end of the branch, and the pixel electrode may include a strip disposed between the branches, and a bar connecting one end of the strip portion.

The counter electrode may be formed in a plate shape, and the pixel electrode may include a plurality of strips overlapping the counter electrode, and a bar connecting one end of the strip portion.

According to the present invention, in the reflective liquid crystal display device, the distance between the electrodes is formed to be smaller than the cell gap so that the counter electrode and the pixel electrode can form a fringe electric field, and the width of the driving electrode is the fringe electric field generated on both sides thereof. As a result, the liquid crystal molecules are formed to be narrow enough so that all of the liquid crystal molecules can be operated, and are formed of a metal film having a high reflectance so that the electrodes act as reflectors while operating all of the liquid crystal molecules present on each electrode.

As a result, it is not necessary to provide a separate reflecting plate, and high transmittance can be obtained.

In addition, the retardation (dΔn) of the liquid crystal layer is set to (2n + 1) λ / 4, and the long axis (or short axis) of the liquid crystal molecules and the electric field are about 45 ° so that light passes through the liquid crystal layer when the electric field is applied. Allow circular polarization. Accordingly, since the conventional half-wave plate acts as a liquid crystal layer, it is not necessary to form a separate half-wave plate.

In addition, since the counter electrode and the pixel electrode have a predetermined height, the counter electrode and the pixel electrode itself act as reflection protrusions, so that the reflected light can be scattered at a much wider angle. Accordingly, the scattering plate does not have to be provided.

Therefore, since the quarter wave plate, the reflecting plate, and the scattering plate are not required in the present invention, the price of the liquid crystal display device can be lowered.

(Example)

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a perspective view of a reflective liquid crystal display device according to the present invention, FIG. 4 is a plan view of a liquid crystal display device according to the present invention, and FIG. 5 is a plan view of a liquid crystal display device according to another embodiment of the present invention. . FIG. 6 is a view for explaining a path of travel of light in an off-white reflective liquid crystal display according to the present invention. 7 is a cross-sectional view of a reflective liquid crystal display device according to an exemplary embodiment of the present invention, and FIGS. 8A to 8C are diagrams for describing a path of light on-time of a reflective liquid crystal display device of a normally white mode according to the present invention.

First, referring to FIGS. 3, 4, and 5, the lower substrate 40 is disposed to face the upper substrate 60 at a predetermined distance d11 (hereinafter, referred to as a cell gap). A liquid crystal layer 65 including several liquid crystal molecules 65a is interposed between the lower substrate 40 and the upper substrate 60. At this time, the liquid crystal layer 65 is a nematic liquid crystal, and may be twisted.

The outer surface of the upper substrate 60 is provided with a polarizing plate 70 for linearly polarizing natural light in a predetermined direction. Here, P represents a polarization axis.

As shown in FIG. 4, on the lower substrate 40, a plurality of gate bus lines 41a and 41b are arranged on the lower substrate 40 at regular intervals and extend in the x direction of the drawing. In addition, the plurality of data bus lines 47a and 47b may also be arranged on the lower substrate 40 at predetermined intervals and extend in the y direction of the drawing to form a matrix unit together with the gate bus lines 41a and 41b. Define the pixel space. A gate insulating film 44 is sandwiched between the gate bus line 41 and the data bus line 47 to insulate them from each other. The common signal line 42 extends in a predetermined direction, for example, the x direction, and is located between the pair of gate bus lines 41a and 41b. For example, the common signal line 42 is preferably disposed closer to the previous gate bus line 41b than the corresponding gate bus line 41a.

The counter electrode 43 is formed in each unit pixel space of the lower substrate 40. Here, the counter electrode 43 is formed on the surface of the lower substrate 40 and is in contact with the common signal line 42. The counter electrode 43 contacts the common signal line 42 to receive a common signal. In this case, the counter electrode 43 includes a body portion 43a parallel to the gate bus lines 41a and 41b and in contact with the common signal line 42, and a plurality of examples extending in the reverse y direction from the body portion 43a. For example, eight branches 43b are included. That is, the counter electrode 43 is formed in the form of a comb. Here, the individual branches 43b are arranged with a constant width P11 and a constant distance L11. The width P11 and the distance L11 of each branch 43b are somewhat narrower than the conventional counter electrode in consideration of the width of the pixel electrode to be formed later and the distance from the pixel electrode.

The pixel electrode 46 is also formed in the unit pixel space of the lower substrate 40, respectively. In this case, the pixel electrode 46 is formed on the gate insulating film 44 so as to overlap the counter electrode 43. The pixel electrode 46 includes a plurality of first parts 46a overlapping with the body part 43a of the counter electrode, and a plurality of examples having a strip shape extending in the reverse y direction from the first part 46a. Second portion 46b. At this time, the second portion 46b has a constant width P12 and is arranged with a constant distance L12 from each other. In addition, the second portion 46b is located between the branches 43b of the counter electrode.

At this time, the counter electrode 430 may be formed in a plate shape, as shown in FIG. The pixel electrode 46 described above may be disposed on the counter electrode 430. Then, the counter electrode 430 is exposed by the space between the second portions 46b of the pixel electrode 46.

In this case, the distance between the second portion 46b of the pixel electrode 46 and the branch 43b of the counter electrode in FIG. 4 and the second portion 46b and the second portion of the pixel electrode 46 in FIG. The distance between the counter electrodes 430 exposed by the two portions 46b is smaller than the distance between the upper and lower substrates. In addition, the widths of the second portion 46b of the pixel electrode 46 and the branch 43b of the counter electrode are formed such that an electric field generated between the two can reach the upper portion of the electrode.

In addition, the counter electrodes 43 and 430 and the pixel electrode 46 are formed of a metal film having a high reflectance, for example, one film selected from Ag, Al, and MgO. In the liquid crystal display of the present invention, since light is a reflection type rather than a transmission type that transmits the lower substrate and the electrodes, the aperture ratio is not determined according to whether the electrode is transparent. If the counter electrodes 43 and 430 and the pixel electrode 46 are formed of a metal film having excellent reflection efficiency, the portions of the electrodes 43 and 46 which occupy most of the area of the unit pixel have reflectivity, and thus no reflection plate is required. .

The thin film transistor 50 which is a switching element is formed near the intersection of the gate bus line 41a and the data bus line 47a, respectively. The thin film transistor 50 includes a channel layer 45 formed on the gate bus line 41a, a drain electrode 48 extending from the data bus line 47a and overlapping with one side of the channel layer 45, and a channel. The source electrode 49 overlaps with the other side of the layer 45 and contacts a predetermined portion of the pixel electrode 46, for example, any one of the second portions.

The storage capacitor Cst is generated at a portion where the counter electrode 43 and the pixel electrode 46 overlap.

Color filters (not shown) are arranged on the inner side of the upper substrate 60.

The first alignment layer 53 is formed on the resultant surface of the lower substrate 40, and the second alignment layer 63 is formed on the inner surface of the color filter of the upper substrate 60. The alignment layers 53 and 63 arrange the liquid crystal molecules 65a in a predetermined direction when no electric field is applied. In addition, the first and second alignment layers 53 and 63 are processed so that the liquid crystal molecules have a pretilt angle of 0 to 10 degrees. The first alignment layer 53 formed on the lower substrate 40 has a ψ angle with respect to the x direction (the direction in which the electric field is formed), preferably about 0 to 45 degrees when the dielectric anisotropy of the liquid crystal molecules is negative. When the dielectric anisotropy is positive, the rubbing is performed to form an angle of about 45 to 90 degrees, and the second alignment layer 63 formed on the upper substrate 60 is anti-parallel, ie, in the rubbing direction of the first alignment layer 53. The rubbing side of the first alignment layer 53 is rubbed so as to be parallel to the rubbing axis of the second alignment layer 63, but the directions thereof are 180 ° to each other.

At this time, in order to operate the reflective liquid crystal display of the present invention as normally white, the polarization axis P of the polarizing plate 70 and the rubbing axis of the second alignment layer 63 are coincident or perpendicular to each other. To operate normally black, the polarization axis P of the polarizing plate 70 and the rubbing axis of the second alignment layer 63 are about ± 0 to 90 °, more preferably about ± 45 ° to each other. This room is preferred.

In the present invention, the quarter wave plate and the scattering plate, which are attached to the conventional reflective liquid crystal display, are not provided. Instead, the liquid crystal layer is set so that the retardation value of the liquid crystal layer 65 represented by the product of the cell gap d11 and the refractive index anisotropy Δn of the liquid crystal satisfies the value of (2n + 1) λ / 4. At 65, it serves as a conventional half-wave plate. In this embodiment, the dielectric anisotropy (Δε) is about 2 to 15, and the refractive index anisotropy (Δn) is about 0.3 to 1.5.

In the present invention, the pixel electrode and the counter electrode, which occupy most of the unit pixel space, are formed of a metal film having a high reflectance, so that the pixel electrode and the counter electrode themselves serve as reflectors.

The operation of the reflective liquid crystal display device having such a configuration will be described.

First, if the gate bus line 41a is not selected, no signal of the data bus line 47a is transmitted to the pixel electrode 46b, and no electric field is formed between the counter electrode 43 and the pixel electrode 46b. . Accordingly, the liquid crystal molecules 65a in the liquid crystal layer 65 are arranged almost parallel to the substrate while their major axes coincide with the rubbing axis.

Then, only components in a predetermined direction among the non-polarized light sources pass through the polarizer 70 and are linearly polarized to the right (or left) as shown in FIG. 6. While the light passing through the polarizing plate 70 passes through the liquid crystal layer 65, the polarization state does not change. In more detail, in the present invention, the liquid crystal molecules of the liquid crystal layer 65 are arranged in a direction in which its long axis is parallel to the substrates 40 and 60 and parallel (or perpendicular) to the polarization axis. Accordingly, since the linearly polarized light passes through the long axis, which is one of the optical axes of the liquid crystal molecules, the polarization state does not change. Therefore, the right linearly polarized state as shown in FIG. 6 is maintained.

Thereafter, the light reaching the lower substrate 40 is reflected by the counter electrodes 43 and 430 and the pixel electrode 46 having a phase difference of 180 degrees to maintain the right linearly polarized state. The reflected light again maintains the polarization state while passing through the liquid crystal layer 65, and passes through the polarizing plate 70. Thus, the screen becomes white.

On the other hand, when a scan signal is applied to the gate bus line 41a and a display signal is applied to the data bus line 47a, the thin film transistor formed near the intersection of the gate bus line 41a and the data bus line 47a ( 50 is turned on and transferred to the pixel electrode 46. At this time, since a common signal having a predetermined voltage difference is continuously applied to the counter electrodes 43 and 430, an electric field is formed between the counter electrodes 43 and 430 and the pixel electrode 46. Here, the portion where the electric field is substantially formed is between the branch portion 43b of the counter electrode 43 and the second portion 46b of the pixel electrode 46. 5, a substantial electric field is formed between the second portion 46b of the pixel electrode 46 and the counter electrode portion exposed by the second portion 46b. At this time, since the distance l11 between the branch portion 43b of the counter electrode 43 and the second portion 46b of the pixel electrode 46 is very narrow as compared with the conventional one, the electric field is smaller than the conventional one as shown in FIG. A parabolic fringe field E _f having a large curvature is generated. At this time, since the widths of the electrodes 43b and 46b are sufficiently narrow, all of the liquid crystal molecules 65a on the electrodes 43b and 46b move only with the fringe field E _f alone. When the fringe field E _f is projected onto the substrate 40, the fringe field E _f and the rubbing axes of the alignment layers 63 and 53 form about ± 45 °. Thus, for example, in the case of using the liquid crystal molecules 65a having positive dielectric anisotropy, the liquid crystal molecules 65a are arranged in parallel with the electric field and the long axis, and the long axis, the polarization axis, and the rubbing axis of the liquid crystal molecule 65a are respectively 45 °. Will be achieved.

When the electric field is formed in this way, the light proceeds as follows.

First, as illustrated in FIG. 8A, only components in a predetermined direction among non-polarized light sources pass through the polarizer 70 and are linearly polarized to the right (or left).

The light passing through the polarizing plate 70 passes through the liquid crystal layer 65 while the retardation is generated to change the polarization state. In other words, the liquid crystal molecules 65a form the rubbing axis (or polarization axis) of the second alignment layer 63 by α °, that is, about 45 °, and the retardation of the liquid crystal layer 65 is performed. Since d11xΔn is (2n + 1) λ / 4 (where n is an integer), light passing through the polarizing plate 70 generates a phase difference equal to the retardation value while passing through the liquid crystal layer 65. Accordingly, the right linearly polarized light is left circularly polarized (or right circularly polarized), as shown in FIG. 8B, with a phase delay of (2n + 1) λ / 4.

Thereafter, light reaching the lower substrate 40 through the liquid crystal layer 65 is reflected by the counter electrodes 43 and 430 and the pixel electrode 46 to have a 180 degree phase difference. Accordingly, it still maintains the left circularly polarized state. In this case, the pixel electrode 46 and the counter electrodes 43 and 430 have a predetermined height as shown in FIG. 7, causing a surface topology. Accordingly, the reflected light is scattered at a wider angle by the topology by the electrodes 46, 43, 430. Therefore, even if no scattering plate is provided, light is scattered and reflected evenly.

Then, the light reflected by the surface of the electrode is reflected to the liquid crystal layer 65, the phase difference is generated by the retardation of the liquid crystal layer 65 again, as shown in Figure 8c, causing the left linear polarization. Then, since the left linearly polarized light passing through the liquid crystal layer 65 is 90 degrees out of phase with the polarization axis (right linearly polarized state) of the polarizing plate 70, it cannot pass through the polarizing plate 70. As a result, the screen becomes dark.

In addition, in contrast to the normal white mode, the normal black mode also shows a dark state before the electric field is applied, and when the electric field is applied, the screen becomes a white state.

As described in detail above, according to the present invention, the following effects are exerted.

First, in the reflective liquid crystal display device, the distance between the electrodes is formed less than the cell gap so that the counter electrode and the pixel electrode can form a fringe electric field, and the width of the driving electrode is the fringe electric field generated on both sides thereof. They are formed to be narrow enough so that they can all be operated, and are formed of a metal film having a high reflectivity, so that the electrodes serve as reflectors while operating all of the liquid crystal molecules present on each electrode.

As a result, it is not necessary to provide a separate reflecting plate, and high transmittance can be obtained.

In addition, the retardation (dΔn) of the liquid crystal layer is set to (2n + 1) λ / 4, and the long axis (or short axis) of the liquid crystal molecules and the electric field are about 45 ° so that light passes through the liquid crystal layer when the electric field is applied. Allow circular polarization. Accordingly, since the conventional half-wave plate acts as a liquid crystal layer, it is not necessary to form a separate half-wave plate.

In addition, since the counter electrode and the pixel electrode have a predetermined height, the counter electrode and the pixel electrode itself act as reflection protrusions, so that the reflected light can be scattered at a much wider angle. Accordingly, the scattering plate does not have to be provided.

Therefore, since the quarter wave plate, the reflecting plate, and the scattering plate are not required in the present invention, the price of the liquid crystal display device can be lowered.

Various embodiments are obvious to those skilled in the art without departing from the spirit and spirit of the invention and can be easily invented. Thus, the claims appended hereto are not limited to those described above, and the claims above include all patented novelties that are inherent in this invention, and furthermore, those of ordinary skill in the art to which this invention pertains. It includes all features processed evenly by the ruler.

Claims (8)

Upper and lower substrates facing each other at a predetermined distance; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; A counter electrode and a pixel electrode disposed on an inner side of the lower substrate and forming a fringe electric field for operating the liquid crystal molecules; A polarizer disposed on an outer surface of the upper substrate and having a predetermined polarization axis; And It is disposed on the inner surface of the upper and lower substrates, respectively, and includes a first and second alignment layer having a predetermined rubbing axis, The counter electrode and the pixel electrode are formed of a highly reflective metal film, The rubbing axis of the first alignment layer has an angle difference of about 0 to 45 degrees when the dielectric anisotropy of the liquid crystal molecules is negative with respect to the direction in which the fringe electric field is formed, and about 45 to 90 degrees when the dielectric anisotropy of the liquid crystal molecules is positive. And a liquid crystal molecule whose retardation (r) value satisfies the following equation. r = (2n + 1) λ / 4 n is an integer The reflective liquid crystal display device according to claim 1, wherein the polarization axis and the rubbing axis of the second alignment layer are coincident or perpendicular to each other. The reflective liquid crystal display device according to claim 1, wherein the polarization axis and the rubbing axis of the second alignment layer form an angle of 0 to 90 degrees. The liquid crystal display of claim 3, wherein the rubbing axis of the polarization axis and the second alignment layer form an angle of about ± 45 °. 2. The reflective liquid crystal display device according to claim 1, wherein the rubbing axis of the first alignment layer and the rubbing axis of the second alignment layer are parallel but their directions have an angle difference of 180 degrees with each other. The reflective liquid crystal display of claim 1, wherein the counter electrode and the pixel electrode are formed of one metal film selected from Ag, Al, and MgO. The method of claim 6, wherein the counter electrode includes a plurality of branches, a body portion connecting one end of the branch, and the pixel electrode connects a strip between each of the branches and a bar connecting one end of the strip portion. Reflective liquid crystal display device comprising a. 7. The reflective liquid crystal display of claim 6, wherein the counter electrode has a plate shape, and the pixel electrode includes a plurality of strips overlapping the counter electrode and one end of the strip portion. Device.