KR100810814B1 - Transflective fringe field switching mode liquid crystal display - Google Patents

Abstract

The present invention discloses a semi-transmissive FFS mode LCD having a single cell gap structure capable of driving at the same low voltage in the transmissive and reflective regions by reducing the driving voltage in the transmissive region. The disclosed method includes a first substrate formed on a reflecting plate formed in a lower substrate, an upper substrate and a reflecting region of the lower substrate, and a lower substrate including the reflecting plate, and formed of a slit type in a transmissive region and a plate in a reflecting region. A transparent electrode, a second transparent electrode disposed on the first transparent electrode with an insulating layer interposed therebetween, the second transparent electrode having a slit shape in both the transmission region and the reflection region, and a lower substrate including the first and second transparent electrodes; And a liquid crystal layer interposed between the lower substrate and the upper substrate.

Description

Transflective fringe field switching mode liquid crystal display

1 is a simulation showing the driving voltage in the transmission region of the conventional transflective FFS mode LCD.

2 is a cross-sectional view showing a manufacturing method of a transflective FFS mode LCD according to the present invention;

3 is a simulation showing the driving voltage in the transmissive region of the transflective FFS mode LCD according to the present invention.

4 is a cross-sectional view showing a part of a lower substrate of a transflective FFS mode LCD according to the present invention;

5 and 6 are plan views showing the pixel structure of the transflective FFS mode LCD according to the present invention.

Explanation of symbols on the main parts of the drawings

11: gate electrode 12: gate insulating film

13: active pattern 14: source / drain electrode

15: resin film 16: reflector

17: linear electrode of the first transparent electrode 18: protective film

19: linear electrode of the second transparent electrode 20: liquid crystal layer

21: thin film transistor 100: lower substrate

200: upper substrate

The present invention relates to a transflective liquid crystal display, and more particularly, to a transflective fringe field switching (FFS) mode liquid crystal display having a single cell gap structure having the same cell gap.

As is well known, a fringe field switching mode LCD (hereinafter referred to as FFS mode LCD) has been proposed to improve the low aperture ratio and transmittance of IPS (In Plane Switching) LCD. In the FFS mode LCD, both the pixel electrode and the common electrode are formed of a transparent conductor such as ITO, and thus, the electrodes have an improved aperture ratio compared to the IPS mode LCD in which the electrodes are made of an opaque metal.

In addition, a fringe field is formed between the pixel electrode and the common electrode by forming a gap between the pixel electrode and the common electrode to be smaller than a gap between the substrates, so that a fringe field is formed on the pixel electrode and the common electrodes. Even the liquid crystal molecules are all operated to obtain improved transmittance.

In general, in a transflective type FFS mode LCD, the pixel electrode is formed in a plate type, the common electrode is formed in a slit type, and the pixel electrode is perpendicular to the formed electrode cross section. As the electric field is formed between the common electrode and the common electrode, the liquid crystal molecules in the pixel are controlled by the electric field.

Here, the slit type refers to a format in which a plurality of slit patterns are arranged at regular intervals in one electrode on a single pixel, and thus a plurality of linear electrodes connected to each other are disposed between the slit patterns.

Meanwhile, in the transflective type FFS mode LCD, an ICR (In Cell Retarder) layer, which is a phase delay film serving as λ / 4, is deposited between the array substrate and the liquid crystal layer. The ICR layer is formed between the common electrode and the liquid crystal layer. Since it serves as a thick dielectric layer in the liquid crystal driving voltage is inevitable.

As such, when the liquid crystal driving voltage rises, the transflective mode becomes difficult to be applied in the display industry such as a mobile or a portable device having the most utility.

For example, as shown in FIG. 1, when the dielectric anisotropy of the liquid crystal is 8, the liquid crystal driving voltage is approximately 8V or more, and even when the dielectric anisotropy is around 15, the liquid crystal driving voltage has a high value of about 7V. .

The reason is that, in general, the deposition of the ICR forms the ICR layer in both the reflection and the transmissive regions by using a printing method, where the twist of the liquid crystal for ON / OFF is 0 ° to 22.5. On the other hand, since the liquid crystal has a twist of 0 ° to 45 ° for on / off transmission, the liquid crystal should rotate twice in the transmission area compared to the reflection area, so that the liquid crystal driving voltage of the reflection area and the transmission area is matched. In order to match, a liquid crystal driving voltage higher than that of the reflection area is required.

On the other hand, in order to compensate for this, in a transflective FFS mode liquid crystal display device having a single cell gap, a method of preventing driving voltage increase in the transmissive region may be considered by removing the ICR by etching in the transmissive region and placing it only in the reflective region. ICR uses neutral organic materials that have polymer structure by UV light and develops process by attaching photo initiator to the panel. It is difficult to etch.

As a result, the conventional transflective type FFS mode LCD is difficult to apply to the mobile display (Mobile Display) is the most easily applied to the transflective mode due to the problem that the liquid crystal drive voltage in the transmissive region is increased.

Accordingly, the present invention has been made to solve the above-mentioned problems, and is a single cell gap transflective FFS mode LCD capable of driving at equal low voltage in the reflective and transmissive regions by suppressing the driving voltage increase in the transmissive regions. The purpose is to provide.

In order to achieve the above object, the present invention is a transflective fringe field switching mode liquid crystal display device having a single cell gap structure of the same cell gap of the transmission region and the reflection region, the lower substrate and the upper substrate; A reflection plate formed in the reflection area of the lower substrate; A first transparent electrode disposed on the lower substrate including the reflective plate and formed in a slit type in a transmissive region and a plate in a reflective region; A second transparent electrode disposed on the first transparent electrode with an insulating layer interposed therebetween, the second transparent electrode having a slit shape in both a transmission region and a reflection region; A phase compensation layer disposed on the lower substrate including the first and second transparent electrodes; An alignment layer formed on the phase compensation layer; It provides a transflective fringe field switching mode liquid crystal display comprising a; and a liquid crystal layer interposed between the lower substrate and the upper substrate.

The first transparent electrode may be a pixel electrode, and the second transparent electrode may be a common electrode.

The first transparent electrode may be a common electrode, and the second transparent electrode may be a pixel electrode.

The first transparent electrode and the second transparent electrode of the transmissive region each include a plurality of linear electrodes disposed at a first interval, and the linear electrode of the first transparent electrode and the linear electrode of the second transparent electrode are horizontally disposed. It is characterized by being disposed with a second interval while alternating with each other.

The linear electrodes of each of the first transparent electrode and the second transparent electrode of the transmissive region have a line width of 2 to 4 μm, and the linear electrodes of each of the first and second transparent electrodes are 6 to 12 μm first. It is arranged at intervals, the linear electrode of the first transparent electrode and the linear electrode of the second transparent electrode is characterized in that it is arranged with a second interval of 2 to 4㎛ horizontally alternate with each other.

The second transparent electrode of the reflective region may include a plurality of linear electrodes disposed at a third interval.

The linear electrodes of the reflective region have a line width of 2 to 4 μm, and each linear electrode is disposed at a third interval of 3 to 6 μm.

The linear electrodes of the second transparent electrode of the transmissive region have the same line width as the linear electrodes of the second transparent electrode of the reflective region and are connected to each other.

The slit-type transparent electrodes of the transmission region and the reflection region include a plurality of linear electrodes extending in the same first direction while being spaced apart from each other, and the alignment layer is oriented in the same second direction to the transmission region and the reflection region. It is characterized by being.

The slit-type transparent electrode of the transmission region and the reflection region includes a plurality of linear electrodes arranged at a predetermined interval, the linear electrode of the transmission region extends in a first direction, and the linear electrode of the reflection region is the first Extending in a second direction different from the second direction, wherein the alignment layer is oriented in a third direction that is the same in the transmission region and the reflection region.

An acute angle formed between the first direction in which the linear electrode of the transmission region extends and the third direction of the alignment layer has an angle smaller than an acute angle formed by the second direction in which the linear electrode of the reflective region extends and the third direction of the alignment layer. It is characterized by.

(Example)

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

First, the "slit type" presented in the present invention, as described above or below, means that a plurality of slit-shaped patterns are arranged at regular intervals in one electrode on a single pixel. It means a shape in which the linear electrode is disposed.

Referring to the technical principle of the present invention, in the transflective type FFS mode LCD having a single cell gap structure of a transmissive region and a reflective region, the transparent electrode contacting the source / drain electrodes is slit in the transmissive region. In the form of a plate, in the reflection region, an increase in driving voltage in the transmission region can be suppressed.

That is, when the transparent electrode is formed in the slit shape on the transmission region, the horizontal field component is larger than the vertical field component to drive the liquid crystal, and thus, a phase compensation film (ICR) serving as a dielectric layer in the transmission region is used. By reducing the influence of a defect element such as the increase of the driving voltage due to the intervening position), the driving voltage can be made small over the pixel region which drives the reflection area and the transmission area at the same time.

In detail, FIG. 2 is a cross-sectional view illustrating a method of manufacturing a semi-permeable FFS mode LCD having a single cell gap structure having the same cell gap according to an embodiment of the present invention.

Referring to FIG. 2, the lower substrate 100 and the upper substrate 200 partitioned into a thin film transistor region TFT, a transmission region T, and a reflection region R face each other under the liquid crystal layer 20. The thin film transistor 21 includes a gate electrode 11, a gate insulating film 12, an active pattern 13, and a source / drain electrode 14 on the thin film transistor region TFT of the lower substrate 100. Is formed, and the via hole V exposing the source / drain electrodes 14 is provided on the entire surface of the substrate 100 including the thin film transistor 21, and has embossing in the reflective region R. The resin film 15 is formed.

The reflective plate 16 is formed on the reflective region R of the lower substrate 100, and the first transparent electrode 17 is formed of a transparent metal film on the entire surface of the lower substrate 100 including the reflective plate 16. ), Preferably, a pixel electrode is formed. In this case, the first transparent electrode 17 is formed to contact the source / drain electrode 14 through the via hole V in the thin film transistor region TFT, and in the transmission region T, the slit is formed. It is formed in a slit type, in the reflective region (R) is formed in a plate type (plate type) so that the portion or the front portion overlaps with the reflecting plate 16.

In addition, a passivation layer 18 including a via hole (not shown) for inputting a signal such as a pad region and an electrostatic circuit is formed on an entire surface of the substrate 100 including the first transparent electrode 17. ), A second transparent electrode 19 made of a transparent metal film, that is, a common electrode is formed.

In this case, the second transparent electrode 19 is formed in a slit type in both the transmission region T and the reflection region R.

Here, the first transparent electrode and the second transparent electrode of the slit shape of the transmission region and the reflection region each include a plurality of linear electrodes arranged at regular intervals.

In addition, an image compensation film (In Cell Retarder, hereinafter referred to as an ICR layer) is formed on the second transparent electrode 19, and an alignment layer is disposed below and above the ICR layer, respectively. Here, the thickness of the ICR layer is such that the product of the refractive index anisotropy (Δn) and the thickness (d) is approximately λ / 4 based on the wavelength of approximately 550 nm, and preferably, of Δn and the thickness d The product has a value between 120 and 150 nm.

Subsequently, although not shown, a semi-polar FFS having a single cell gap structure having the same cell gap according to an embodiment of the present invention is formed by forming a lower polarizing plate and an upper polarizing plate on the outer side of the lower substrate 100 and the upper substrate 200, respectively. Manufacture a mode LCD.

According to the present invention, the first transparent electrode 17, which is a transparent metal film, is formed in a plate shape in the reflection area R and a slit shape in the transmission area T, and thus, in the electric field formation, the reflection area R is formed. Compared with this, in the transmission region T, the horizontal electric field component increases.

Therefore, by generating a large horizontal electric field component in the transmissive region where a relatively large liquid crystal rotation is required compared to the reflective region, it is possible to compensate for the difference in driving voltage according to the difference in the liquid crystal rotation of the reflective region and the transmissive region. The driving voltage of the transmissive region can be matched to the same low voltage level.

Therefore, as a result, the present invention can reduce the magnitude of the driving voltage which is effective in the reflection area and the transmission area at the same time, so that a high quality liquid crystal display device can be realized.

As described above, according to the present invention, when the first transparent electrode is formed of a pixel electrode in a slit shape in the transmission region T, and the dielectric anisotropy of the liquid crystal is increased to 12 or more, the driving voltage in the transmission region is examined. , The same result as in FIG. 3 was obtained.

3, when the pixel electrode is plate-shaped in the transmissive region according to the related art, compared with FIG. 1 showing the driving voltage in the transmissive region, it has a driving voltage of 4.5 kV which is approximately 2 kHz lower than the conventional art. It can be seen that.

Accordingly, a liquid crystal display device that compensates for a difference in driving voltages between the reflection area and the transmission area for the liquid crystal twist and matches the effective driving voltage capable of simultaneously driving the transmission area and the reflection area to a low voltage level can be implemented.

4 is a cross-sectional view showing the width of the linear electrode and the distance between the linear electrodes in the first transparent electrode and the second transparent electrode formed in the transmission region and the reflection region, as shown in FIG. 4. The widths W1 and W2 of the linear electrodes 17 and 19 of the electrode and the second transparent electrode are each 6 μm or less, preferably 2 to 4 μm, and the first transparent electrode in the transmission region T. And the intervals L1 and L2 between the linear electrodes 17 and 19 of the second transparent electrode are 16 μm or less, preferably 6 to 12 μm, and the first transparent electrode is disposed in the transmission region T. The linear electrodes 17 and the linear electrodes 19 of the second transparent electrode are horizontally alternated with each other and are arranged at regular intervals. The linear electrodes 17 of the first transparent electrode and the linear electrodes of the second transparent electrode are arranged. The horizontal spacing L3 of (19) is 6 micrometers or less, Preferably it is comprised so that it may have 2-4 micrometers.

In addition, the width W3 of the linear electrode 19 of the second transparent electrode in the reflection region R is equal to 6 μm, which is the same as the width W2 of the linear electrode 19 of the second transparent electrode of the transmission region T. Preferably, it is comprised so that it may have 2-4 micrometers, and the space | interval L4 between the linear electrodes 19 of a 2nd transparent electrode in the said reflection area R is 6 micrometers or less, Preferably, 3-6 micrometers Configure to have.

As described above, the width of the linear electrode and the distance between the linear electrodes have a large influence on the driving voltage and transmittance, so that the driving voltage and transmittance can be optimized according to the use of the liquid crystal display device within the range described above. You can change it freely.

5 and 6 are plan views showing the pixel structure. In the embodiment of the present invention, as shown in FIG. 5, the linear electrodes on the reflection area and the transmission area are disposed at the same angle at an angle of 90 °, and are reflected. By rubbing the alignment film of the region and the transmissive region at an angle of 83 °, a predetermined angle (83 °) in which the electrical field direction (0 °) and the rubbing direction (83 °) of the alignment layer are equally selected in the reflective and transmissive regions It can have

Meanwhile, in another embodiment of the present invention, as shown in FIG. 6, the linear electrodes on the reflective area are disposed at an angle of 100 °, and in contrast, the linear electrodes on the transmissive area are disposed at an angle of 90 °. By rubbing the alignment film in the region and the transmissive region at an angle of 83 °, the angle formed by the electrical field direction (10 °) and the rubbing direction (83 °) of the alignment layer in the reflective region (73 °) is determined by the electrical field direction (0) in the transmissive region. °) and the rubbing direction (83 °) of the alignment film can be configured to be smaller than the angle (83 °).

As described above, when the linear electrode placement angle (100 °) of the reflection area is made larger than the linear electrode placement angle (90 °) of the transmission area, the angle formed by the electric field direction and the rubbing direction becomes small, and thus, reflection As the driving voltage in the region is increased, it is possible to further compensate the difference between the driving voltages of the reflective and transmissive regions.

As described above, through the embodiments related to the arrangement angle of the linear electrodes formed on the transmission region and the reflection region and the rubbing direction of the alignment layer, the angle between the electrical field direction and the rubbing direction of the alignment layer in the transmission region and the reflection region is the same. In other embodiments, those skilled in the art will readily recognize that the angle formed by the electrical field direction of the reflective region and the rubbing direction of the alignment layer may be implemented at a smaller angle than the transmission region.

In addition, in the embodiment related to the arrangement angle of the linear electrode and the rubbing direction of the alignment layer described above, the arrangement angle of the preceding electrode and the rubbing direction of the alignment layer are set to a specific value, but the present invention is not limited to the specific value shown. Those skilled in the art will readily appreciate that various modifications may be made depending on the use and characteristics of the display device.

Meanwhile, in various embodiments of the present invention described above, the first transparent electrode is formed as the pixel electrode and the second transparent electrode is used as the common electrode, but the present invention is not limited thereto. Those skilled in the art can readily recognize that the first transparent electrode can be formed using the common electrode and the second transparent electrode can be formed as the pixel electrode.

As mentioned above, although specific embodiments of the present invention have been described and illustrated, modifications and variations can be made by those skilled in the art. Accordingly, the following claims are to be understood as including all modifications and variations as long as they fall within the true spirit and scope of the present invention.

As described above, the present invention, when forming a semi-transmissive FFS mode LCD having a wide viewing angle characteristics while having the characteristics of high transmissivity and high reflectance, all of the lower transparent electrode and the upper transparent electrode formed in the transmissive area in a slit type And the lower transparent electrode formed in the reflective area is formed in a plate shape, and the upper transparent electrode is formed in a slit type, so that an electric field having a relatively horizontal component is generated in the transmissive area compared to the reflective area. The difference in driving voltage of the region can be compensated for.

Accordingly, a liquid crystal display device capable of matching an effective driving voltage capable of simultaneously driving the transmission area and the reflection area to a low voltage level can be implemented.

Claims (11)

A transflective fringe field switching mode liquid crystal display device having a single cell gap structure in which cell gaps of a transmission area and a reflection area are the same, A lower substrate and an upper substrate; A reflection plate formed in the reflection area of the lower substrate; A first transparent electrode disposed on the lower substrate including the reflective plate and formed in a slit type in a transmissive region and a plate type in a reflective region; A second transparent electrode disposed on the first transparent electrode with an insulating layer interposed therebetween, the second transparent electrode having a slit shape in both a transmission region and a reflection region; A phase compensation layer disposed on the lower substrate including the first and second transparent electrodes; An alignment layer formed on the phase compensation layer; And A liquid crystal layer interposed between the lower substrate and the upper substrate; Transflective fringe field switching mode liquid crystal display comprising a. The method of claim 1, The first transparent electrode is a pixel electrode, the second transparent electrode is a transflective fringe field switching mode liquid crystal display, characterized in that the common electrode. The method of claim 1, The first transparent electrode is a common electrode, the second transparent electrode is a semi-transparent fringe field switching mode liquid crystal display, characterized in that the pixel electrode. The method of claim 1, The first transparent electrode and the second transparent electrode of the transmissive region each include a plurality of linear electrodes disposed at a first interval, and the linear electrode of the first transparent electrode and the linear electrode of the second transparent electrode are horizontally disposed. A transflective fringe field switching mode liquid crystal display, characterized in that arranged alternately with a second interval. The method of claim 4, wherein The linear electrodes of each of the first transparent electrode and the second transparent electrode of the transmissive region have a line width of 2 to 4 μm, and the linear electrodes of each of the first and second transparent electrodes are 6 to 12 μm first. Semi-transparent fringe field switching, wherein the linear electrodes of the first transparent electrode and the linear electrodes of the second transparent electrode are alternately arranged horizontally with a second interval of 2 to 4 μm. Mode liquid crystal display device. The method of claim 1, The transflective fringe field switching mode liquid crystal display of claim 2, wherein the second transparent electrode of the reflective region includes a plurality of linear electrodes disposed at a third interval. The method of claim 6, And the linear electrodes of the reflective region have a line width of 2 to 4 mu m, and each linear electrode is disposed at a third interval of 3 to 6 mu m. The method according to any one of claims 4 to 7, And the linear electrodes of the second transparent electrode of the transmissive region have the same line width as the linear electrodes of the second transparent electrode of the reflective region and are connected to each other. The method of claim 1, The slit-type transparent electrodes of the transmission region and the reflection region include a plurality of linear electrodes extending in the same first direction while being spaced apart from each other, and the alignment layer is oriented in the same second direction to the transmission region and the reflection region. And a transflective fringe field switching mode liquid crystal display. The method of claim 1, The slit-type transparent electrode of the transmission region and the reflection region includes a plurality of linear electrodes arranged at a predetermined interval, the linear electrode of the transmission region extends in a first direction, and the linear electrode of the reflection region is the first A transflective fringe field switching mode liquid crystal display, extending in a second direction different from the second direction, wherein the alignment layer is aligned in a third direction equal to the transmission region and the reflection region. The method of claim 10, An acute angle formed between the first direction in which the linear electrode of the transmission region extends and the third direction of the alignment layer has an angle smaller than an acute angle formed by the second direction in which the linear electrode of the reflective region extends and the third direction of the alignment layer. A transflective fringe field switching mode liquid crystal display, characterized in that.

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