KR101204234B1 - Single gap transflective liquid crystal display using Optically Isotropic Liquid Crystal Mixtures - Google Patents

Abstract

The present invention relates to a semi-transmissive liquid crystal display device consisting of a single gap, in the transmissive region when showing a bright state using a liquid crystal having a positive dielectric anisotropy optically isotropically changed from isotropic to anisotropic by an electric field When the voltage is applied to the liquid crystal, the birefringence is induced along the electric field direction so that the phase delay value of the liquid crystal layer is λ / 2, and the liquid crystal in the reflection region is optically isotropic due to no voltage applied, and the phase delay value is 0, resulting in bright state. Indicates. When the dark state is indicated, the phase delay value is 0 because no voltage is applied in the transmissive region, and the voltage is applied to the liquid crystal layer in the reflecting region to induce birefringence along the electric field direction, and thus the phase delay value is λ / 4. The electric field relates to a single gap transflective liquid crystal display device using a fringe or horizontal electric field and using an optically isotropic liquid crystal mixture.

Description

Single gap transflective liquid crystal display using Optically Isotropic Liquid Crystal Mixtures}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transflective liquid crystal display (hereinafter referred to as LCD) consisting of a single gap with a liquid crystal having a positive dielectric anisotropy that changes optically isotropic to anisotropic by an electric field.

Currently, the liquid crystal display device occupies a large part in the global flat panel display market, and the liquid crystal display device has been developed by focusing on the wide viewing angle characteristic to overcome the limitations, starting with the conventional TN mode. As a solution, in-plane switching (IPS), fringe field switching (FFS) mode or patterned vertical alignment (PVA) mode has been proposed, and these modes exhibit good optical and transmittance characteristics. As a transmissive liquid crystal display device expressing information using a backlight, which is an internal light source, it is highly competitive in comparison with other technologies due to its high image quality, but when applied to a portable device, visibility is inferior due to a strong external light source. Therefore, the transflective liquid crystal display device uses a backlight light in a room where the external light source is dark to switch by controlling the director of the liquid crystal, and reflects the external light source in order to improve outdoor visibility in a bright outdoor environment to express an image indoor or outdoor. It has high competitiveness in the portable display market by increasing visibility.

 However, in the conventional transflective liquid crystal display device, the cell gap of the reflection area and the transmission area is a double gap, which requires an additional process, and a large amount of compensation film needs to be added, thus causing a problem of high manufacturing cost. In addition, the nematic liquid crystal phase mainly used in such a liquid crystal display device uses a method in which the optical axis of the liquid crystal is initially arranged in advance in a batch to change the polarization state of light transmitted from the light source according to the direction of the liquid crystal. Therefore, rubbing process is inevitable. Such a rubbing process is an operation which rubs the surface of the oriented film apply | coated to the board | substrate surface which contact | connects a liquid crystal with cloth etc., and this causes the cost of a yield fall, or the quality deterioration of a liquid crystal display element.

Accordingly, an object of the present invention is to provide a single gap cell gap between the reflection area and the transmission area in order to solve the problem of the background art, and optically isotropic liquid crystal mixture that can reduce the manufacturing cost without using a large amount of compensation film It is to provide a single gap semi-transmissive liquid crystal display device using.

In addition, another object of the present invention is to improve the process yield by using an optically isotropically anisotropic liquid crystal that can eliminate the rubbing process to reduce the process yield and increase the reaction rate of the liquid crystal to increase the process yield and a good response speed It is to provide a liquid crystal display device having a.

In order to achieve the above object, the present invention provides a preferred embodiment of the single-gap semi-transmissive liquid crystal display device using the optically isotropic liquid crystal mixture according to the present invention, the upper polarizing plate; An upper substrate positioned below the upper polarizer; A liquid crystal layer filled in the transmissive and reflective regions having the same cell gap under the upper substrate; A slit-shaped pixel electrode positioned below the liquid crystal layer of the transmission and reflection region and patterned at regular intervals; A first common electrode for a transmissive region patterned at regular intervals on the same or different layer as the pixel electrode; A second common electrode for the reflective regions patterned at regular intervals patterned on the same layer as the first common electrode; Forming one gate electrode line and one data electrode line to transmit a signal to each pixel; A switching element formed at an intersection of the one gate electrode line and the one data electrode line; A lower substrate positioned below the common electrode; The transflective film is attached to the lower substrate. Here, the present invention is characterized by varying the voltage of the first common electrode and the second common electrode in order to indicate the dark state during the initial driving. In addition, the present invention preferably includes attaching a polarizing plate to the lower part of the transflective film.

In addition, another embodiment of the present invention, the upper polarizing plate; An upper substrate positioned below the upper polarizer; A liquid crystal layer filled in the transmissive and reflective regions having the same cell gap under the upper substrate; A first pixel electrode of a slit type positioned below the liquid crystal layer of the transmission region and patterned at regular intervals; A second pixel electrode of a slit type positioned below the liquid crystal layer of the reflective region and patterned at regular intervals; A common electrode patterned at regular intervals on the same or different layer as the pixel electrode; Forming two gate electrode lines and one data electrode line to transmit a signal to each pixel; Two switching elements each formed at an intersection of the two gate electrode lines and one data electrode line; A lower substrate positioned below the common electrode; The transflective film is attached to the lower substrate. Here, the present invention is characterized by varying the voltage of the first common electrode and the second common electrode in order to indicate the dark state during the initial driving. In addition, the present invention preferably includes attaching a polarizing plate to the lower part of the transflective film.

In addition, another embodiment of the present invention, the upper polarizing plate; An upper substrate positioned below the upper polarizer; A liquid crystal layer filled in the transmissive and reflective regions having the same cell gap under the upper substrate; A slit-shaped pixel electrode positioned below the liquid crystal layer of the transmission and reflection region and patterned at regular intervals; An insulating layer under the pixel electrode; A first common electrode for a planar transmissive region under the insulating layer; A second common electrode for a reflective region positioned on the same layer as the first common electrode; Forming one gate electrode line and one data electrode line to transmit a signal to each pixel; A switching element formed at an intersection of the one gate electrode line and the one data electrode line; A lower substrate positioned below the common electrode; A polarizer is attached to the lower substrate. Here, the present invention is characterized by varying the voltage of the first common electrode and the second common electrode in order to indicate the dark state during the initial driving.

In addition, another embodiment of the present invention, the upper polarizing plate; An upper substrate positioned below the upper polarizer; A liquid crystal layer filled in the transmissive and reflective regions having the same cell gap under the imaginary upper substrate; A first pixel electrode of a slit type positioned below the liquid crystal layer of the transmission region and patterned at regular intervals; A second pixel electrode of a slit type positioned below the liquid crystal layer of the reflective region and patterned at regular intervals; An insulating layer under the pixel electrode; A common electrode having a transparent electrode formed in a planar shape in a transmissive area below the insulating layer and a reflective electrode having an embossed shape in a reflective area; Forming two gate electrode lines and one data electrode line to transmit a signal to each pixel; Two switching elements each formed at an intersection of the two gate electrode lines and one data electrode line; A lower substrate positioned below the common electrode; A polarizer is attached to the lower substrate. Here, the present invention is characterized by varying the voltage of the first common electrode and the second common electrode in order to indicate the dark state during the initial driving.

In addition, another embodiment of the present invention, the upper polarizing plate; An upper substrate positioned below the upper polarizer; A liquid crystal layer filled under the upper substrate; A slit pixel electrode positioned below the liquid crystal layer and patterned at regular intervals; A common electrode patterned at regular intervals on the same or different layer as the pixel electrode; Forming a gate electrode line and a data electrode line to transmit a signal to each pixel; One switching element formed at an intersection of the one gate electrode line and the data electrode line; A lower substrate positioned below the common electrode; The transflective film is attached to the lower substrate. Here, the optical state of the reflection mode and the transmission mode of the present invention is characterized by being adjusted by the applied voltage.

In addition, another embodiment of the present invention, the upper polarizing plate; An upper substrate positioned below the upper polarizer; A liquid crystal layer filled under the upper substrate; A slit pixel electrode positioned below the liquid crystal layer and patterned at regular intervals; An insulating layer under the pixel electrode; A common electrode having a planar shape under the insulating layer; Forming a gate electrode line and a data electrode line to transmit a signal to each pixel; One switching element formed at an intersection of the one gate electrode line and the data electrode line; A lower substrate positioned below the common electrode; The transflective film is attached to the lower substrate. Here, the optical state of the reflection mode and the transmission mode of the present invention is characterized by being adjusted by the applied voltage.

As described in detail above, by applying different voltages to the reflective and transmissive regions, different phase delay values of the initial liquid crystal are provided, thereby providing a semi-transmissive liquid crystal display device having a single gap structure. In addition, since the present invention does not require a built-in phaser patterning process without using various types of bodhisattva films, thickness and manufacturing cost are reduced. This single-gap semi-transmissive LCD will greatly improve yield and image quality, and can be used as a transmissive type and reflective type, so that visibility can be secured in any environment regardless of the intensity of the external light source.

In addition, according to the present invention, since the rubbing process is not necessary, the yield deterioration and the deterioration of the device quality generated during the rubbing process can be eliminated.

In addition, according to the present invention, by using a liquid crystal that is optically isotropically anisotropically changed by voltage application, a response speed of μs is realized, and thus, a natural video can be realized as compared with a nematic liquid crystal.

1 is a structural diagram of a blue phase liquid crystal applied to the present invention.
2 is a plan view and a cross-sectional view for explaining a single gap transflective liquid crystal display device according to Embodiment 1 of the present invention.
3 is a plan view for explaining a change in voltage application in each unit pixel according to Embodiment 1 of the present invention;
Figure 4a is an optical schematic diagram of the optical isotropic, anisotropic change state, that is, the dark state by applying the electric field of the blue phase liquid crystal according to Example 1 of the present invention.
Figure 4b is an optical schematic diagram of the optical isotropic, anisotropic change state, that is, the bright state by applying the electric field of the blue phase liquid crystal according to Example 1 of the present invention.
5 is a plan view and a sectional view for explaining a single-gap semi-transmissive liquid crystal display device according to a second embodiment;
6 is a plan view and a sectional view for explaining a single-gap semi-transmissive liquid crystal display device according to a third embodiment;
7 is a plan view for explaining a change in voltage application in each unit pixel according to Embodiment 3 of the present invention;
8A is an optical schematic diagram of an optically isotropic and anisotropic change state, i.e., a dark state, by application of an electric field of a blue phase liquid crystal according to Example 3 of the present invention;
8B is an optical schematic diagram of an optically isotropic and anisotropic change state, i.e., a bright state, by application of an electric field of a blue phase liquid crystal according to Example 1 of the present invention;
9 is a plan view and a cross-sectional view for explaining the single-gap semi-transmissive liquid crystal display device according to the fourth embodiment.
10 is a plan view and a sectional view for explaining a single-gap semi-transmissive liquid crystal display device according to the fifth embodiment;
FIG. 11A is an optical schematic diagram of optically isotropic and anisotropic change state, that is, a reflection-type dark state, by application of an electric field of a blue liquid crystal according to Example 5 of the present invention; FIG.
FIG. 11B is an optical schematic diagram of optically isotropic and anisotropic change state of the blue liquid crystal according to Example 5 of the present invention by applying an electric field;
12 is a plan view and a sectional view for explaining a single-gap semi-transmissive liquid crystal display device according to the sixth embodiment;
FIG. 13A is a schematic diagram of optically isotropic and anisotropic change states of the blue phase liquid crystal according to Example 6 of the present invention, that is, a reflective dark state optical state; FIG.
13B is an optically isotropic and anisotropic change state of the blue phase liquid crystal according to Example 6 of the present invention, that is, a transmissive dark state optical schematic diagram.

The present invention relates to a semi-transmissive liquid crystal display device composed of a single gap with a liquid crystal having a positive dielectric anisotropy optically isotropically anisotropically changed by an electric field.

1 is a structure of a blue phase liquid crystal. As shown in the figure, birefringence of the blue liquid crystal 5 occurs from the optically isotropic state (5-a) to the optically anisotropic state (5-b) according to the application of the electric field. The blue phase liquid crystal is a liquid crystal phase present in the temperature range between the cholesteric nematic phase and the isotropic phase, and has a first blue phase lattice structure and a second blue phase lattice structure (2-a, 2-b) and has a cylinder inside the lattice. (1-a) exists and the liquid crystal is twisted twice by the chiral dopant inside the cylinder (1-b), and is optically isotropic (5-a) before voltage is applied.

However, when the voltage is applied, as shown in Equation (1), the Kerr effect is generated by the external electric field and refractive index anisotropy is generated (5-b).

Δ n = λ KE ² (1)

(Δ n = induced refractive anisotropy, λ = wavelength of light source used, K = Kerr constant, E = electric field energy)

However, the photocurable polymer using ultraviolet rays in the defect regions (3-a, 3-b) where the liquid crystal is not present in the blue phase lattice structure because the temperature range where the blue phase liquid crystal is present is so narrow that it is not suitable for use as a display. A network is formed (4) to expand the range of existence at room temperature.

Examples of the chemical structure of the liquid crystal, chiral dopant, monomolecular, and photoinitiator belonging to the liquid crystal layer which changes optically isotropic to anisotropic are as follows.

LCD

Chiral Dopant

 -Single molecule-

-Photo Initiator-

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

Example 1

Example 1 is a single-gap semi-transmissive liquid crystal display using an optically isotropic liquid crystal mixture which applies the IPS mode and separates the common electrodes of the transmission and reflection areas to adjust the initial phase delay value of the liquid crystal located in the transmission and reflection areas. Device.

2 is a plan view and a cross-sectional view of a unit pixel of a single gap transflective liquid crystal display device according to Embodiment 1 of the present invention. As illustrated, an upper substrate 2 formed of a glass substrate is positioned below the upper polarizing plate 1, and a liquid crystal layer exists in the same cell gap in the transmissive and reflective region below the upper substrate 2. The transparent region (T-region) and the reflective region (R-region) are coated with a transparent pixel electrode 4 which is patterned in a slit form at regular intervals, and the transparent region crosses the pixel electrode 4 with each other. Has a structure of an array substrate on which a first common electrode 6 is coated and a second common electrode 7 is coated in a reflection area. Therefore, when the thin film transistor (TFT) is turned on through the gate electrode line, the data signal passes through the drain electrode and the silicon active layer and the source electrode of the TFT through the data electrode line. An electric charge flows in. In this case, since the transmissive region and the pixel electrode 4 of the reflective region are directly connected to each other, the TFT may be in either the reflective region or the transmissive region, and the first common electrode 6 of the transmissive region and the reflective region may be formed. Since the two common electrodes 7 are connected by different wirings, the degree of charge inflow in the transmission area and the reflection area is controlled, and can be driven by one TFT.

FIG. 3 shows the pixel electrode 4 of FIG. 2 together with the first common electrode 6 in the transmission region and the second common electrode 7 in the reflection region in a dark state showing the change of voltage applied to each unit pixel. A phase of the liquid crystal layer 3 is applied to the second common electrode 7 of the reflective region in which the birefringence voltage is not generated in the first common electrode 6 of the transmissive region as one pixel electrode. A delay value may apply a voltage at which λ / 4 can be derived. Since the liquid crystal layer 3 of the transmission region is optically isotropic because it is not influenced by an electric field, the liquid crystal layer 3 exhibits a dark state, and the liquid crystal layer 3 in the reflection region may induce birefringence to the second common electrode 7. Since a birefringence occurs due to the direction of the electric field and the phase delay value is λ / 4, the pixel electrode 4 and the second common electrode 7 form 45 degrees to the upper polarizing plate 1 because the voltage is applied. Of unpolarized light passes through the upper polarizing plate 1 having a transmission axis of 45 degrees, and the 45 degree linearly polarized light passes circularly polarized light while passing through the liquid crystal layer 3 having a phase delay value of λ / 4. Comes out. Thereafter, the circularly polarized light is reflected by the semi-transmissive film 11 and again passes through the liquid crystal layer 3 having a phase delay value of λ / 4, and becomes a linearly polarized light. Because they meet perpendicular to the transmission axis, light is absorbed to represent the dark state. At this time, the bright state of the reflection area and the transmission area can be obtained by changing the voltage of the first common electrode 6 and the second common electrode 7.

4A is a cross-sectional view taken along line A-A 'and line B-B' of FIG. 2 to show a dark state. 4A is a cross-sectional view of a transmissive region and a reflective region, in which an upper polarizing plate 1 is placed on an upper glass substrate 2 and a liquid crystal layer 3 is disposed below an upper glass substrate 2. The lower glass substrate 10 is positioned below the liquid crystal layer 3, and the lower transflective film 11 is positioned below the lower glass substrate 10. The liquid crystal is optically isotropic because the liquid crystal is not influenced by the electric field at the lower portion of the upper glass substrate 2 in the transmissive region, and thus shows a dark state. If birefringence occurs along the direction and the phase delay value is λ / 4, the pixel electrode 4 and the second common electrode 7 form 45 degrees to the upper polarizing plate 1 so that the externally unpolarized light The light passes through the upper polarizing plate 1 having a transmission axis of 45 degrees, and the light linearly polarized at 45 degrees emerges as circularly polarized light while passing through the liquid crystal layer 3 having a phase delay value of λ / 4. Subsequently, the circularly polarized light is reflected by the semi-transmissive film 11 and again passes through the liquid crystal layer 3 having a phase delay value of λ / 4 to become vertically polarized light, thereby transmitting the upper polarizing plate 1. Because they meet perpendicular to the axis, light is absorbed to represent the dark state.

4B is a cross-sectional view taken along lines A-A 'and B-B' of FIG. 2 to show a bright state. 4B is a cross-sectional view of a transmissive region and a reflective region, in which an upper polarizing plate 1 is placed on the upper glass substrate 2, and a liquid crystal layer 3 is disposed below the upper glass substrate 2. The lower glass substrate 10 is positioned below the liquid crystal layer 3, and the lower transflective film 11 is positioned below the lower glass substrate 10. When the pixel electrode 4 and the first common electrode 6 in the transmissive region form 45 degrees to the upper polarizing plate 1, when light passing through the liquid crystal layer 3 senses a λ / 2 phase difference in the liquid crystal layer 3 The maximum transmittance is generated, showing a bright state. In addition, since the liquid crystal is optically isotropic because no voltage is applied to the reflective region, light that is not externally polarized is incident on the upper polarizing plate 1 by 45 degrees and comes out as light reflected by the reflecting plate, thereby showing a bright state.

Example 2

Example 2 relates to a single-gap semi-transmissive liquid crystal display device using an optically isotropic liquid crystal mixture using two TFTs, unlike the electrode structure of Example 1. The driving state of the transflective liquid crystal display device having this electrode structure is the same as that of the first embodiment.

5 is a plan view and a cross-sectional view illustrating a unit pixel of a single gap transflective liquid crystal display device according to Embodiment 2 of the present invention. An upper substrate 2 formed of a glass substrate is positioned below the upper polarizing plate 1, and the liquid crystal layer 3 exists in the same cell gap in the transmissive and reflective regions below the upper substrate 2. The transparent common electrode 6, which is patterned in a slit pattern at regular intervals, is coated in the transmission region T-region and the reflection region R-region under the liquid crystal layer 3. The first pixel electrode 4 is coated in the transmissive region and the second pixel electrode 5 is coated in the reflective region in a cross-sectional shape. The gate electrode lines and the common electrode signal lines are arranged in parallel to each other in the horizontal direction on the lower insulating substrate, and the data electrode lines are arranged in the vertical direction with respect to the gate electrode lines and the common electrode signal lines to define a unit pixel space. do. In this case, two gate electrode lines, one common electrode signal line, and one data electrode line are shown to represent one unit pixel space. The structure of the array substrate of the first pixel electrode 4 and the second pixel electrode 5, which are separated from each other based on the common electrode signal wiring, in order to apply voltages having different polarities or intensities to the transmission region and the reflection region, respectively. As a result, the degree of charge inflow in the transmissive and reflective regions is controlled, and two TFTs can be driven.

Example 3

Example 3 differs from Example 1 using a single optically isotropic liquid crystal mixture that applies the FFS mode and separates the common electrodes of the transmissive and reflective regions to adjust the initial phase delay values of the liquid crystals located in the transmissive and reflective regions. It is a gap type transflective liquid crystal display device.

6 is a plan view illustrating a unit pixel of a single gap transflective liquid crystal display device according to a third exemplary embodiment of the present invention. An upper substrate 2 formed of a glass substrate is positioned below the upper polarizing plate 1, and the liquid crystal layer 3 exists in the same cell gap in the transmissive and reflective regions of the lower portion of the upper substrate 2. The transmissive region (T-region) and the reflecting region (R-region) are coated with pixel electrodes 4 which are patterned in a slit form at regular intervals, and an insulating layer 8 is provided under the pixel electrodes 4. And a second common electrode 6 'formed in a planar shape on the lower substrate 10 in the transmission region below the insulating layer 8 and an embossed shape on the lower substrate 10 in the reflection region. The electrode 7 'is located. The reflective and transmissive regions exist simultaneously as pixel electrodes in one pixel, and both the reflective and transmissive regions are driven by a fringe electric field. Since the transmissive region and the pixel electrode 4 of the reflecting region are directly connected to each other, the TFT may be in either the reflecting region or the transmissive region, and the first common electrode 6 'of the transmissive region and the second of the reflecting region Since the common electrode 7 ′ is connected by different wirings, the degree of charge inflow in the transmission region and the reflection region is controlled, and it can be driven by one TFT.

FIG. 7 is a dark state showing the change of voltage applied to each unit pixel between the first common electrode 6 'and the second common electrode 7' in the transmissive region of the pixel electrode 4 of FIG. Is a planar view, wherein a voltage in which birefringence does not occur in the liquid crystal layer 3 is applied to the first common electrode 6 'of the transmission region as one pixel electrode, and the liquid crystal layer 3 is applied to the second common electrode 7' of the reflection region. Can be applied a voltage at which λ / 4 can be derived. Since the liquid crystal layer 3 in the transmission region is optically isotropic because it is not influenced by an electric field, the liquid crystal layer 3 exhibits a dark state. In the reflection region, the birefringence may be induced in the second common electrode 7 ′. Since a birefringence is generated in accordance with the direction of the electric field and a phase delay value of λ / 4 is induced, the pixel electrode 4 and the second common electrode 7 'form 45 degrees to the upper polarizer 1. Therefore, external unpolarized light passes through the upper polarizing plate 1 having a transmission axis of 45 degrees, and the light linearly polarized at 45 degrees passes circularly polarized light while passing through the liquid crystal layer 3 having a phase delay value of λ / 4. Comes out light. Subsequently, the circularly polarized light is reflected by the lower embossing reflective electrode 7 'and passes through the liquid crystal layer 3 having a phase delay value of λ / 4. Since it meets perpendicular to the transmission axis of 1), light is absorbed to express the dark state. In this case, the bright state of the reflection area and the transmission area can be obtained by changing the voltages of the first common electrode 6 'and the second common electrode 7'.

FIG. 8A is a cross-sectional view taken along lines A-A 'and B-B' of FIG. 7 to show a dark state. As shown, FIG. 8A is a cross-sectional view of a transmissive region and a reflective region, in which an upper polarizing plate 1 is placed on the upper glass substrate 2, and a liquid crystal layer 3 is disposed below the upper glass substrate 2. The pixel electrode 4 and the lower embossed reflective electrode 7 ′ are positioned below the reflective region liquid crystal layer 3 with the insulating layer 8 interposed therebetween. A common electrode 6 ′ is formed, and a lower polarizer is positioned below the lower glass substrate 10 (12). Since the liquid crystal is optically isotropic because the liquid crystal is not affected by the electric field at the lower portion of the upper glass substrate 2 in the transmissive region, it shows a dark state, and the fringe electric field is placed on the liquid crystal placed under the upper glass substrate 2 in the reflective region. When the birefringence is applied with a voltage such that the phase delay value λ / 4 is induced in the direction of, the externally unpolarized light has a transmission axis of 45 degrees because the pixel electrode 4 forms 45 degrees to the upper polarizing plate 1. Light linearly polarized through 45 degrees through the upper polarizing plate 1 passes through the liquid crystal layer 3 having a phase delay value of λ / 4, resulting in circularly polarized light. Subsequently, the circularly polarized light is linearly polarized light by passing through the liquid crystal layer 3 having a phase delay value of λ / 4 again by circularly polarized light by the lower reflective electrode 7 '. Since it meets perpendicular to the transmission axis of 1), light is absorbed to express the dark state.

8B is a cross-sectional view taken along line A-A 'and line B-B' of FIG. 7 to show a bright state. As shown, FIG. 8B is a cross-sectional view of a transmissive region and a reflective region, in which an upper polarizing plate 1 is placed on the upper glass substrate 2, and a liquid crystal layer 3 is disposed below the upper glass substrate 2. The pixel electrode 4 and the lower embossed reflective electrode 7 ′ are positioned below the reflective region liquid crystal layer 3 with the insulating layer 8 interposed therebetween. A common electrode 6 ′ is formed, and a lower polarizer is positioned below the lower glass substrate 10 (12). Since the pixel electrode 4 of the transmissive region forms 45 degrees to the upper polarizing plate 1, when the light passing through the liquid crystal layer 3 senses a λ / 2 phase difference in the liquid crystal layer 3, a maximum transmittance occurs and is in a bright state. Will be displayed. In addition, since the liquid crystal is optically isotropic because no voltage is applied to the reflective region, light that is not externally polarized is incident on the upper polarizing plate 1 by 45 degrees and comes out as light reflected by the reflecting plate, thereby showing a bright state.

Example 4

Example 4 relates to a single-gap semi-transmissive liquid crystal display device using two TFTs, unlike the electrode structure of Example 3. The driving state of the transflective liquid crystal display device using the optically isotropic liquid crystal mixture having this electrode structure is the same as in the third embodiment.

9 is a plan view and a cross-sectional view illustrating a unit pixel of a single gap transflective liquid crystal display device according to Embodiment 4 of the present invention. An upper substrate 2 formed of a glass substrate is positioned below the upper polarizing plate 1, and the liquid crystal layer 3 exists in the same cell gap in the transmissive and reflective regions below the upper substrate 2. In the transmissive region below the liquid crystal layer 3, the first pixel electrode 4 patterned in the slit form at regular intervals and the second pixel electrode 5 patterned in the slit form at regular intervals in the reflective region. Located there is an insulating layer 8 at the bottom. The lower common electrode 9 having a planar shape is coated under the insulating layer. The data electrode lines are arranged in a vertical direction with respect to the gate electrode lines to define a unit pixel space. In this case, two gate electrode lines, one common electrode signal line, and one data electrode line are shown to represent one unit pixel space. Since the first and second pixel electrodes 4 and 5, which are separated from each other based on the common electrode signal wiring, are coated to apply voltages having different polarities or intensities to the transmission and reflection areas, the transmission is performed. By controlling the degree of charge inflow in the region and the reflection region, it is possible to drive with two TFTs.

Example 5

Embodiment 5 relates to a liquid crystal display device using an optically isotropic liquid crystal mixture that drives the entire surface in a transmissive form or drives the entire surface in a reflective form according to a voltage applied without separating the transmissive and reflective regions in the pixel using the IPS mode. will be.

10 is a plan view and a cross-sectional view illustrating a unit pixel of a liquid crystal display according to a fifth exemplary embodiment of the present invention. As shown, an upper substrate 2 formed of a glass substrate is positioned below the upper polarizing plate 1, and a liquid crystal layer 3 is present below the upper substrate 2. An array substrate having a transparent pixel electrode 4 coated in a slit pattern at regular intervals under the liquid crystal layer 3 and coated with a common electrode 6 in a form intersecting with the pixel electrode 4. Has the structure Accordingly, when the thin film transistor (TFT) is turned on through the gate electrode line, the data signal passes through the drain electrode of the TFT and the silicon active layer and the source electrode through the data electrode line. Electric charges flow into the device, and in this case, a single TFT can be driven. The transmission type and the reflection type can be adjusted by the voltage applied to the liquid crystal layer 3.

FIG. 11A is a cross-sectional view taken along line AA ′ of FIG. 10, showing a reflective dark state. As shown, FIG. 11A is a cross-sectional view of a reflective type, in which an upper polarizing plate 1 is placed on an upper glass substrate 2, a liquid crystal layer 3 is disposed below an upper glass substrate 2, and a liquid crystal layer. The lower glass substrate 10 is positioned at the lower part of (3), and the lower semi-transmissive film 11 is positioned at the lower part of the lower glass substrate 10. When birefringence occurs in the liquid crystal positioned under the upper glass substrate 2 in all regions according to the direction of the electric field, and the phase delay value is λ / 4, the pixel electrode 4 and the common electrode 6 become the upper polarizing plate. Since it is 45 degrees in (1), the externally unpolarized light passes through the upper polarizing plate 1 having a transmission axis of 45 degrees, and the 45 degree polarized light has a phase delay value of λ / 4. Passing through (3), it comes out as circularly polarized light. Subsequently, the circularly polarized light is reflected by the semi-transmissive film 11 and again passes through the liquid crystal layer 3 having a phase delay value of λ / 4 to become vertically polarized light, thereby transmitting the upper polarizing plate 1. Because they meet perpendicular to the axis, light is absorbed to represent the dark state.

FIG. 11B is a cross-sectional view taken along the line AA ′ of FIG. 10 to show a transmissive dark state. As shown in FIG. 11B, a cross-sectional view of a transmissive type is provided in which an upper polarizing plate 1 is placed on the upper glass substrate 2, a liquid crystal layer 3 is disposed below the upper glass substrate 2, and a liquid crystal layer ( The lower glass substrate 10 is positioned at the lower part of 3), and the lower transflective film 11 is positioned at the lower part of the lower glass substrate 10. Since no voltage is applied to the entire area and the liquid crystal is optically isotropic, the light emitted from the backlight passes through the liquid crystal layer 3 and does not feel a phase difference, thereby showing a dark state.

Example 6

Unlike the electrode structure of the fifth embodiment, the sixth embodiment is optically isotropic to drive the entire surface in a transmissive form or the front side in a reflective form according to the voltage applied without separating the transmissive and reflective regions in the pixel using the FFS mode. It relates to a liquid crystal display device using a liquid crystal mixture.

12 is a plan view and a sectional view of a unit pixel according to a sixth embodiment of the present invention. An upper substrate 2 formed of a glass substrate is positioned below the upper polarizing plate 1, and a liquid crystal layer 3 exists below the upper substrate 2. The lower portion of the liquid crystal layer 3 is coated with a pixel electrode 4 which is patterned in a slit form at regular intervals, and an insulating layer 8 exists below the pixel electrode 4, and the lower portion of the insulating layer 8 The array electrode structure is coated with a common electrode 9 formed in a planar shape on the lower substrate 10 in all regions of the substrate. The reflection type and the transmission type can be adjusted by changing the voltage applied to the liquid crystal layer 3, and both are driven by a fringe electric field. The data electrode lines are arranged in a vertical direction with respect to the gate electrode lines to define a unit pixel space. In this case, in order to represent one unit pixel space, one gate electrode line, one common electrode signal line, and one data electrode line are illustrated, and in this case, one TFT may be driven.

FIG. 13A is a cross-sectional view taken along line AA ′ of FIG. 12, showing a reflective dark state. As shown, FIG. 13A is a cross-sectional view of a reflective type, in which an upper polarizing plate 1 is placed on the upper glass substrate 2, a liquid crystal layer 3 is disposed below the upper glass substrate 2, and the liquid crystal is formed. The pixel electrode 4 and the common electrode 9 having a lower planar shape are positioned under the layer 3 with the insulating layer 8 interposed therebetween, and the lower transflective film 11 under the lower glass substrate 10. ) Is located. When the voltage is applied to the liquid crystal layer 3 positioned below the upper glass substrate 2 in the entire area so that the birefringence phase delay value λ / 4 is induced in accordance with the direction of the fringe electric field, the pixel electrode 4 is arranged on the upper polarizing plate. Since the non-polarized light passes through the upper polarizing plate 1 having the transmission axis of 45 degrees and the light polarized by 45 degrees to (1), the liquid crystal layer 3 has a phase delay value of λ / 4. The circularly polarized light comes out as it passes through. Subsequently, the circularly polarized light is linearly polarized light by passing through the liquid crystal layer 3 having a phase delay value of λ / 4 again by the lower semi-transmissive plate 11 to become a vertically polarized light. Since it meets perpendicular to the transmission axis of 1), light is absorbed to express the dark state.

FIG. 13B is a cross-sectional view taken along the line AA ′ of FIG. 12 to show a transmissive dark state. As shown, FIG. 13B is a cross-sectional view of a transmissive type, in which an upper polarizing plate 1 is placed on the upper glass substrate 2, a liquid crystal layer 3 is disposed below the upper glass substrate 2, and the liquid crystal layer is formed. A pixel electrode 4 and a common electrode 9 having a lower planar shape are positioned under the insulating layer 8 with the insulating layer 8 interposed therebetween, and the lower transflective film 11 under the lower glass substrate 10. Is located. Since no voltage is applied to the liquid crystal layer 3 and the liquid crystal is optically isotropic, the light emitted from the backlight passes through the liquid crystal layer 3 and does not feel a phase difference, thereby showing a dark state.

In the above described as a preferred embodiment of the present invention, but is not limited to the above-described embodiment of the present invention, those who have ordinary knowledge in the field of the invention without departing from the gist of the invention claimed in the claims Anyone can make a variety of variations.

1. Upper polarizer plate 2. Upper substrate
3. Liquid crystal layer 4. First pixel electrode
5. Second pixel electrode 6. First common electrode
7. Second common electrode 8. Lower insulating layer
9. Lower common electrode 10. Lower substrate
11. Lower transflective film 12. Lower polarizer

Claims (9)

An upper polarizer;
An upper substrate positioned below the upper polarizer;
A liquid crystal layer filled in the transmissive and reflective regions having the same cell gap under the upper substrate;
A slit-shaped pixel electrode positioned below the liquid crystal layer of the transmission and reflection region and patterned at regular intervals;
A first common electrode for a transmissive region patterned at regular intervals on the same or different layer as the pixel electrode;
A second common electrode for the reflective regions patterned at regular intervals patterned on the same layer as the first common electrode;
Forming one gate electrode line and one data electrode line to transmit a signal to each pixel;
A switching element formed at an intersection of the one gate electrode line and the one data electrode line;
A lower substrate positioned below the common electrode;
Single-gap type semi-transmissive liquid crystal display device using an optically isotropic liquid crystal mixture, characterized in that the semi-transmissive film is attached to the lower substrate An upper polarizer;
An upper substrate positioned below the upper polarizer;
A liquid crystal layer filled in the transmissive and reflective regions having the same cell gap under the upper substrate;
A first pixel electrode of a slit type positioned below the liquid crystal layer of the transmission region and patterned at regular intervals;
A second pixel electrode of a slit type positioned below the liquid crystal layer of the reflective region and patterned at regular intervals;
A common electrode patterned at regular intervals on the same or different layer as the pixel electrode;
Forming two gate electrode lines and one data electrode line to transmit a signal to each pixel;
Two switching elements each formed at an intersection of the two gate electrode lines and one data electrode line;
A lower substrate positioned below the common electrode;
Single-gap type semi-transmissive liquid crystal display device using an optically isotropic liquid crystal mixture, characterized in that the semi-transmissive film is attached to the lower substrate 3. The method according to claim 1 or 2,
Single-gap semi-transmissive liquid crystal display device using an optically isotropic liquid crystal mixture comprising attaching a polarizing plate to the lower part of the transflective film An upper polarizer;
An upper substrate positioned below the upper polarizer;
A liquid crystal layer filled in the transmissive and reflective regions having the same cell gap under the upper substrate;
A slit-shaped pixel electrode positioned below the liquid crystal layer of the transmission and reflection region and patterned at regular intervals;
An insulating layer under the pixel electrode;
A first common electrode for a planar transmissive region under the insulating layer;
A second common electrode for a reflective region positioned on the same layer as the first common electrode;
Forming one gate electrode line and one data electrode line to transmit a signal to each pixel;
A switching element formed at an intersection of the one gate electrode line and the one data electrode line;
A lower substrate positioned below the common electrode;
Single-gap type semi-transmissive liquid crystal display device using an optically isotropic liquid crystal mixture, characterized in that the polarizing plate is attached to the lower substrate An upper polarizer;
An upper substrate positioned below the upper polarizer;
A liquid crystal layer filled in the transmissive and reflective regions having the same cell gap under the upper substrate;
A first pixel electrode of a slit type positioned below the liquid crystal layer of the transmission region and patterned at regular intervals;
A second pixel electrode of a slit type positioned below the liquid crystal layer of the reflective region and patterned at regular intervals;
An insulating layer under the pixel electrode;
A common electrode having a transparent electrode formed in a planar shape in a transmissive area below the insulating layer and a reflective electrode having an embossed shape in a reflective area;
Forming two gate electrode lines and one data electrode line to transmit a signal to each pixel;
Two switching elements each formed at an intersection of the two gate electrode lines and one data electrode line;
A lower substrate positioned below the common electrode;
Single-gap type semi-transmissive liquid crystal display device using an optically isotropic liquid crystal mixture, characterized in that the polarizing plate is attached to the lower substrate delete An upper polarizer;
An upper substrate positioned below the upper polarizer;
A liquid crystal layer in which a liquid crystal layer of one pixel filled under the upper substrate is divided into a transmission region and a reflection region having the same sal gap;
A slit pixel electrode positioned below the liquid crystal layer and patterned at regular intervals;
A common electrode patterned at regular intervals on the same or different layer as the pixel electrode;
Forming a gate electrode line and a data electrode line to transmit a signal to each pixel;

One switching element formed at an intersection of the one gate electrode line and the data electrode line;
A lower substrate positioned below the common electrode;
Single-gap type semi-transmissive liquid crystal display device using an optically isotropic liquid crystal mixture, characterized in that the reflective, transmissive mixed film is attached to the lower substrate An upper polarizer;
An upper substrate positioned below the upper polarizer;
A liquid crystal layer filled under the upper substrate;
A slit pixel electrode positioned below the liquid crystal layer and patterned at regular intervals;
An insulating layer under the pixel electrode;
A common electrode having a planar shape under the insulating layer;
Forming a gate electrode line and a data electrode line to transmit a signal to each pixel;
One switching element formed at an intersection of the one gate electrode line and the data electrode line;
A lower substrate positioned below the common electrode;
Single-gap type semi-transmissive liquid crystal display device using an optically isotropic liquid crystal mixture, characterized in that the semi-transmissive film is attached to the lower substrate The single-gap semi-transmissive type according to claim 7 or 8, wherein an optical state of a reflection mode and a transmission mode of one pixel is applied differently to light so that light is controlled differently in each region. LCD display device

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