LCD device having a first panel with a flat surface plate-like portion and a bar like second portion, with a spacer between the first and a second panel contacting the flat surface plate-like first portion, and overlapping pixel electrode without overlapping signal lines disposed in the bar-like second portion

A liquid crystal display device according to an exemplary embodiment includes: a first panel comprising a first portion and a second portion, wherein the first portion has a height lower than of the second portion; a second panel facing the first panel; a spacer disposed between the first panel and the second panel and contacting the first portion of the first panel; and a liquid crystal layer disposed between the first panel and the second panel.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

(b) Description of Related Art

A liquid crystal display (LCD) device is one of the most widely used flat panel display devices. An LCD device includes two panels provided with field-generating electrodes such as pixel electrodes and a common electrode and a liquid crystal (LC) layer interposed therebetween. The LCD device displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer, which determines orientations of LC molecules in the LC layer to adjust polarization of incident light.

The LCD device further includes thin film transistors (TFTs) and a plurality of signal lines for transmitting signals to the TFTs, which include gate lines transmitting gate signals, data lines transmitting data signals, and storage electrode lines supplied with a common voltage and overlapping the pixel electrodes.

The LCD device further includes a plurality of spacers forming a gap filled with the LC layer. The spacers include bead spacers irregularly spread over the panels and columnar spacers or rigid spacers regularly arranged on the panels.

The columnar spacers are usually formed of a photoresist film by coating, light exposure, and development. The columnar spacers are usually disposed on opaque members such as the signal lines and the thin film transistors.

The LCD device is often subjected to pressure or impact. The impact may make the columnar spacers slide out of their initial positions, and the spacers try to recover their positions due to their elasticity.

However, the spacers may not return to their initial positions and may remain at the distorted positions if there are obstacles such as steps in the returning path. Consequently, the orientations of the LC molecules near the spacers may be distorted and cause light leakage.

SUMMARY OF THE INVENTION

A liquid crystal display device according to an exemplary embodiment includes: a first panel comprising a first portion and a second portion, wherein the first portion has a height lower than of the second portion; a second panel facing the first panel; a spacer disposed between the first panel and the second panel and contacting the first portion of the first panel; and a liquid crystal layer disposed between the first panel and the second panel.

In another exemplary embodiment, the spacer may be formed on the second panel and may be disposed near the second portion of the first panel. Additionally, the second portion of the first panel may be opaque. Furthermore, the second portion of the first panel may enclose the first portion of the first panel.

The first portion of the first panel may include a pixel electrode and the second portion of the first panel may include a signal line. The second panel may include a common electrode generating an electric field in cooperation with the pixel electrode.

The second panel may further include a light blocking member that faces the second portion of the first panel and partly faces the first portion of the first panel and the spacer may overlap the light blocking member.

The pixel electrode and the common electrode may be transparent.

The liquid crystal display device may further include a plurality of color filters disposed on either the first panel or the second panel. The color filters may include a red filter, a green filter, and a blue filter and the spacer may overlap the blue filter.

The first portion of the first panel may include a plate-like conductor and the second portion of the first panel comprises a bar-like conductor.

A liquid crystal display device according to another exemplary embodiment includes: a first panel including a first substrate, a plurality of signal lines disposed on the first substrate, a plurality of thin film transistors connected to the signal lines, and a plurality of pixel electrodes connected to the thin film transistors; a second panel facing the first panel; a plurality of spacers that are disposed between the first panel and the second panel, face the pixel electrodes, and are disposed near the signal lines without overlapping the signal lines; and a liquid crystal layer disposed between the first panel and the second panel.

The signal lines may include a plurality of gate lines, a plurality of data lines traversing the gate lines, and a plurality of storage electrode lines overlapping the pixel electrodes.

The liquid crystal display device may further include a plurality of color filters disposed on one of the first and the second panels. The color filters may include a red filter, a green filter, and a blue filter and the spacers overlap the blue filters.

A liquid crystal display device according to another embodiment of the present invention includes: a first panel including a first substrate, a plurality of signal lines disposed on the first substrate, a plurality of thin film transistors connected to the signal lines, and first and second pixel electrodes connected to the thin film transistors and having substantially the same shape; a second panel facing the first panel and including a light blocking member that includes a first opening facing the first pixel electrodes and a second opening facing the second pixel electrodes and having a small area than the first opening; a plurality of spacers that are disposed on the light blocking member, contact the first panel, and face the second pixel electrodes; and a liquid crystal layer disposed between the first panel and the second panel.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings, the thickness of layers and regions are exaggerated for clarity. Like numerals refer to like elements throughout. It will be understood that when an element such as a layer, region or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

An LCD device according to an exemplary embodiment of the present invention will be described in detail with reference toFIGS. 1,2and3.

FIG. 1is a layout view of an LCD device according to an exemplary embodiment of the present invention, andFIGS. 2 and 3are sectional views of the LCD device shown inFIG. 1taken along lines II-II′ and III-III′-III″, respectively.

Referring toFIGS. 1-3, an LCD device according to an exemplary embodiment of the present invention includes a TFT array panel100, a common electrode panel200, and a LC layer3interposed between the TFT array panel100and the common electrode panel200.

The TFT array panel100will be described in further detail.

A plurality of gate lines121and a plurality of storage electrode lines131are formed on an insulating substrate110, which may be constructed of transparent glass or plastic.

A gate line121transmits a gate signal and extends substantially in a transverse direction. The gate line121includes a gate electrodes124projecting downward and an end portion129having a large area for contact with another layer or an external driving circuit. A gate driving circuit (not shown) for generating the gate signal may be mounted on a flexible printed circuit (FPC) film (not shown), which may be attached to the substrate110, directly mounted on the substrate110, or integrated onto the substrate110. The gate line121may extend to be connected to a driving circuit (not shown) that may be integrated on the substrate110.

A storage electrode line131is supplied with a predetermined voltage and each includes a stem extending substantially parallel to the gate line121and a pair of first and second storage electrodes133aand133bextending in a longitudinal direction from the stem. The storage electrode line131is disposed between two adjacent gate lines121and the stem is close to a lower one of the two adjacent gate lines121. Each of the first and second storage electrodes133aand133bis shaped like a straight bar and has a fixed end portion connected to the stem and a free end portion disposed opposite thereto and disposed near the gate line121. Since the gate electrode124projects downward, the fixed end portion of the first storage electrode133afaces the gate electrode124along the transverse direction and the second storage electrode133bis shorter than the first storage electrode133a. However, it will be appreciated that the storage electrode line131may have various shapes and arrangements.

In an exemplary embodiment, the gate line121and the storage electrode line131are made of, including but not limited to, Al containing metal such as Al and Al alloy, Ag containing metal such as Ag and Ag alloy, Cu containing metal such as Cu and Cu alloy, Mo containing metal such as Mo and Mo alloy, Cr, Ta, or Ti. However, the gate line121and the storage electrode line131may have a multi-layered structure including two conductive films (not shown) that have different physical characteristics. One of the two conductive films is made of, including but not limited to, low resistivity metal including Al containing metal, Ag containing metal, and Cu containing metal for reducing signal delay or voltage drop. The other conductive film is made of, including but not limited to, material such as Mo containing metal, Cr, Ta, or Ti, which has good physical, chemical, and electrical contact characteristics with other materials such as indium tin oxide (ITO) or indium zinc oxide (IZO). Examples of the combination of the two films are a lower Cr film and an upper Al (alloy) film and a lower Al (alloy) film and an upper Mo (alloy) film. However, it is contemplated that the gate line121and the storage electrode line131may also be made of various metals or conductors.

The lateral sides of the gate line121and the storage electrode line131are inclined relative to a surface of the substrate110, and the inclination angle thereof ranges from about 30 degrees to about 80 degrees.

A gate insulating layer140, made of, including but not limited to, silicon nitride (SiNx) or silicon oxide (SiOx), is formed on the gate line121and the storage electrode line131. However, it is contemplated that the insulating layer140may be of any other suitable material.

A plurality of semiconductor stripes151, made of, including but not limited to, hydrogenated amorphous silicon (abbreviated to “a-Si”) or polysilicon, are formed on the gate insulating layer140. A semiconductor stripe151extends substantially in the longitudinal direction and become wide near the gate lines121and the storage electrode lines131such that the semiconductor stripe151covers a large area of the gate line121and the storage electrode line131. The semiconductor stripes151includes a projection154branched out toward the gate electrode124.

A plurality of ohmic contact stripes and ohmic contact islands165are formed on the semiconductor stripes151. The ohmic contact stripes and islands165are made of, including but not limited to, n+ hydrogenated a-Si heavily doped with n type impurity such as phosphorous or they may be made of silicide. Each ohmic contact stripe includes a projection163. The projection163and an ohmic contact island165are located in pairs on the projection154of the semiconductor stripe151.

The lateral sides of the semiconductor stripe151and the ohmic contact stripe and island165are inclined relative to the surface of the substrate110, and the inclination angles thereof are in a range, including but not limited to, from about 30 degrees to about 80 degrees.

A data line171and a drain electrode175are formed on the ohmic contacts stripes and island165and the gate insulating layer140.

The data line171transmits data signals and extends substantially in the longitudinal direction to traverse the gate line121and the storage electrode line131. The data line171also traverse the storage electrode line131and runs between adjacent pairs of storage electrodes133aand133b. The data line171includes a plurality of source electrodes173each projecting toward the gate electrode124and an end portion179having a large area for contact with another layer or an external driving circuit. The data line171may be curved in shape, for example, in a particular exemplary embodiment the data line171may have a shape similar to the character J. A data driving circuit (not shown) for generating the data signal may be mounted on a FPC film (not shown), which may be attached to the substrate110, directly mounted on the substrate110, or integrated onto the substrate110. The data line171may extend to be connected to a driving circuit that may be integrated on the substrate110.

The drain electrode175is separated from the data line171and disposed opposite the source electrode173with respect to the gate electrode124. The drain electrode175includes a wide end portion and a narrow end portion. The wide end portion overlaps the storage electrode line131and the narrow end portion is partly enclosed by the source electrode173.

The gate electrode124, the source electrode173, and the drain electrode175along with the projection154of the semiconductor stripe151form a TFT having a channel formed in the projection154disposed between the source electrode173and the drain electrode175.

The data line171and the drain electrode175are made of, including but not limited to, refractory metal such as Cr, Mo, Ta, Ti, or alloys thereof. However, the data line171and the drain electrode175may have a multilayered structure including a refractory metal film (not shown) and a low resistivity film (not shown). Examples of the multi-layered structure are a double-layered structure including a lower Cr/Mo (alloy) film and an upper Al (alloy) film and a triple-layered structure of a lower Mo (alloy) film, an intermediate Al (alloy) film, and an upper Mo (alloy) film. However, it is contemplated that the data line171and the drain electrode175may be made of various metals or conductors.

The data line171and the drain electrode175have inclined edge profiles, and the inclination angles thereof range from about 30 degrees to about 80 degrees.

The ohmic contacts stripe and island165are interposed between the underlying semiconductor stripe151and the overlying conductors171and175thereby reducing the contact resistance therebetween. Although the semiconductor stripe151is generally narrower than the data line171, the width of the semiconductor stripe151becomes larger near the gate line121and the storage electrode line131as described above, to smooth the profile of the surface, thereby preventing the disconnection of the data line171. The semiconductor stripe151includes some exposed portions, which are not covered with the data line171and the drain electrode175, such as portions located between the source electrode173and the drain electrode175.

A passivation layer180is formed on the data line171, the drain electrode175, and the exposed portions of the semiconductor stripe151. The passivation layer180is made of, including but not limited to, an inorganic or organic insulator and it may have a flat top surface. Examples of the inorganic insulator include silicon nitride and silicon oxide. The organic insulator may have photosensitivity and dielectric constant less than about 4.0. The passivation layer180may include a lower film made of inorganic insulator and an upper film made of organic insulator such that it takes the excellent insulating characteristics of the organic insulator while preventing the exposed portions of the semiconductor stripe151from being damaged by the organic insulator.

The passivation layer180has a first contact hole182and a second contact hole185exposing the end portion179of the data line171and the drain electrode175, respectively. The passivation layer180and the gate insulating layer140have a third hole181exposing the end portion129of the gate line121, a fourth contact hole183aexposing portions of the storage electrode line131near the fixed end portions of the storage electrode133a, and a fifth contact hole183bexposing the free end portions of the storage electrode133a.

A plurality of pixel electrodes191, a plurality of overpasses83, a plurality of first contact assistants81, and a second contact assistant82are formed on the passivation layer180. They are made of, but not limited to, transparent conductor such as ITO or IZO or reflective conductor such as Ag, Al, Cr, or alloys thereof.

A pixel electrode191is physically and electrically connected to the drain electrode175through the second contact hole185such that the pixel electrode191receives data voltages from the drain electrode175. The pixel electrode191is supplied with the data voltages and generates an electric field in cooperation with a common electrode270of the common electrode panel200. The common electrode270is supplied with a common voltage, which determines the orientations of liquid crystal molecules of a liquid crystal layer3disposed between the pixel electrode191and the common electrode270. The pixel electrode191and the common electrode270form a capacitor referred to as a “liquid crystal capacitor,” which stores applied voltages after the TFT turns off.

The pixel electrode191overlaps the storage electrode line131including the pair of first and second storage electrodes133aand133bsuch that the pixel electrode191fully covers a portion of a stem of the storage electrode line131. The left and right edges of the pixel electrode191are disposed on the pair of first and second storage electrodes133aand133b. The pixel electrode191and the drain electrode175connected thereto and form an additional capacitor referred to as a “storage capacitor” with the storage electrode line131, which enhances the voltage storing capacity of the liquid crystal capacitor.

In addition, the pixel electrode191also overlaps the gate line121disposed adjacent to the pixel electrode191such that the aperture ratio is increased. An upper edge of the pixel electrode191is disposed on the gate line121and extends along a lower edge of the gate line121.

An overpass83crosses over the gate line121and is connected to the exposed portions of the storage electrode line131and the exposed linear branches of the free end portions of the first storage electrode133athrough the fourth contact hole183aand the fifth contact hole183b, respectively, which are disposed opposite each other with respect to the gate line121. The storage electrode line131including the storage electrodes133aand133balong with the overpass83can be used for repairing defects in the gate line121, the data line171, or the TFTs.

A first contact assistant81and a second contact assistant82are connected to the end portion129of the gate line121and the end portion179of the data line171through the third contact hole181and the first contact hole182, respectively. The first contact assistant81and the second contact assistant82protect the end portions129and179and enhance the adhesion between the end portions129and179and external devices.

An alignment layer11that may be homogeneous or homeotropic is formed on the pixel electrode191and the passivation layer180.

The description of the common electrode panel200follows with reference toFIGS. 2-4.

A light blocking member220referred to as a black matrix for preventing light leakage is formed on an insulating substrate210which may be made of transparent glass or plastic. The light blocking member220has a first opening225and a second opening226that face the pixel electrode191. It is contemplated that the light blocking member220may have a plurality of first and second openings. The boundary of the first opening225and the second opening226are disposed on the pixel electrode191and extends along the boundary of the pixel electrode191. All the edges of the first opening225are disposed close to edges of the pixel electrode191to expose an area between a fixed end portion of a first storage electrode and the gate electrode124. However, the second opening226has an upper edge spaced apart from an upper edge of a pixel electrode191such that the light blocking member220covers an area between a fixed end portion of a first storage electrode and the gate electrode124. The light blocking member220also covers a boundary of a display area that is provided with the pixel electrode191.

A plurality of color filters230are also formed on the substrate210and disposed substantially in the area enclosed by the light blocking member220such that edges of the color filter230are disposed on the light blocking member220. A color filter230may extend substantially along the longitudinal direction along the pixel electrode191. The color filter230represents one of the primary colors such as red R, green G and blue B as shown inFIG. 1.

An overcoat250is formed on the color filters230and the light blocking member220. The overcoat250is, for example, made of an (organic) insulator and it prevents the color filters230from being exposed and provides a flat surface.

The common electrode270is formed on the overcoat250. The common electrode270is made of, including but not limited to, a transparent conductive material such as ITO and IZO.

A plurality of columnar spacers320are formed on the common electrode270and disposed opposite the light blocking member220. A columnar spacer320is, for example, made of an elastic insulating material and has contact portions that contact the TFT array panel100, to provide support for the TFT array panel100, and the common electrode panel200. The spacer320faces the pixel electrode191and it is disposed on an area enclosed by a fixed end portion of a first storage electrode, the gate line121, the gate electrode124, and an upper edge of the second opening226.

However, it will be appreciated that the place where a spacer320contacts on the TFT array panel100is not limited to the above-described location.

In an exemplary embodiment, the spacer320may contact any place of the TFT array panel100that is relatively low as compared with other places on the TFT array panel100and may have a flat surface. In this configuration, although the contact portions of the spacer320may slide out of the correct positions due to a pressure or an impact exerted on the panels100and200, the contact portions can return to the correct positions. On the contrary, if a spacer320is disposed on a higher place relative to other places on the TFT array panel100and the higher place occupies a small area, if the contact portion of the spacer320slides out of the higher place to reach a lower place it may not return to its initial position due to the step between the higher place and the lower place. The failure of the spacer320to return to the lower place may cause light leakage.

In another exemplary embodiment, the contact place is disposed near opaque members, such as the gate line121, the storage electrode131, the data line171, etc., in order to reduce light leakage.

In yet a further exemplary embodiment, the spacers320are disposed on the blue color filters B as shown inFIG. 1since human eyes are less sensitive to blue color as compared with red and green colors.

An alignment layer21that may be homogeneous or homeotropic is formed on the common electrode270and the spacer320.

In an exemplary embodiment, a pair of polarizers12and22are provided on outer surfaces of the panels100and200, respectively. However, it is also contemplated that one of the polarizers12and22may be omitted when the LCD device is a reflective LCD device.

The LCD device may further include a retardation film (not shown) for compensating the retardation of the LC layer3. The retardation film has birefringence and gives a retardation opposite to that given by the LC layer3.

The LCD device may also further include a backlight unit (not shown) supplying light to the LC layer3through the polarizers12and22, the retardation film, and the panels100and200.

The LC layer3may have positive or negative dielectric anisotropy and it may be subjected to either a horizontal alignment or a vertical alignment in absence of an electric field.

An LCD device according to another exemplary embodiment of will now be described in further detail with reference toFIGS. 4,5and6.

FIG. 4is a layout view of an LCD device according to another exemplary embodiment andFIGS. 5 and 6are sectional views of the LCD device shown inFIG. 4taken along lines V-V′ and VI-VI′-VI″, respectively.

Referring toFIGS. 4-6, an LCD device according to this exemplary embodiment also includes a TFT array panel100, a common electrode panel200, and a LC layer3interposed between the panels100and200.

Regarding the TFT array panel100, the gate line121including the gate electrode124and the end portion129, and the storage electrode line131including the storage electrodes133aand133bare formed on the substrate110. The gate insulating layer140, the semiconductor stripe151including the projection154, and the ohmic contacts161and165including the projection163are sequentially formed on the gate line121and the storage electrodes line131. The data line171including the source electrode173and the end portion179and the drain electrode175are formed on the ohmic contacts161and165. The passivation layer180is formed on the data line171, the drain electrode175, and exposed portions of the semiconductors154. The third contact hole181, the first contact hole182, and the second contact hole185are provided at the passivation layer180and the gate insulating layer140. The pixel electrode191, the overpass83, the first contact assistant81, and the second contact assistant82are formed on the passivation layer180, and the alignment layer11is coated thereon.

Regarding the common electrode panel200, a light blocking member220, the color filter230, the overcoat250, the common electrode270, the columnar spacer320, and the alignment layer21are formed on the insulating substrate210.

In an alternative exemplary embodiment of the LCD device, the semiconductor stripe151have almost the same planar shape as the data line171and the drain electrode175as well as the underlying ohmic contacts161and165. However, the semiconductor151includes some exposed portions, which are not covered with the data line171and the drain electrode175, such as portions located between the source electrode173and the drain electrode175.

A manufacturing method of the TFT array panel according to an exemplary embodiment simultaneously forms the data line171, the drain electrode175, the semiconductor151, and the ohmic contacts161and165using one photolithography step.

In another exemplary embodiment, a photoresist masking pattern for the photolithography process may have a position-dependent thickness, and in particular, it has thicker portions and thinner portions. The thicker portions are located on wire areas that will be occupied by the data line171and the drain electrode175and the thinner portions are located on channel areas of TFTs.

The position-dependent thickness of the photoresist may be obtained by several techniques, including but not limited to, providing translucent areas on the exposure mask as well as transparent areas and light blocking opaque areas. The translucent areas may have a slit pattern or a lattice pattern. Alternatively, the translucent film may be a thin film(s) with intermediate transmittance or intermediate thickness. When using a slit pattern, the width of the slits or the distance between the slits may be smaller than the resolution of a light exposer used for the photolithography. In another exemplary embodiment a reflowable photoresist may be used. Once a photoresist pattern made of a reflowable material is formed using a normal exposure mask with transparent areas and opaque areas, it is subject to a reflow process including flow onto areas without the photoresist. The reflow process may be used to form thin portions. In another exemplary embodiment, the manufacturing process may be simplified by omitting a photolithography step.

Many of the above-described features of the LCD device shown inFIGS. 1-3may be applied to the LCD device shown inFIGS. 4-6.

An LCD device according to another exemplary embodiment of the present invention will now be described in further detail with reference toFIG. 7.

FIG. 7is a sectional view of the LCD device shown inFIG. 1taken along line II-II′.

Referring toFIG. 7, the LCD device includes the TFT array panel100, the common electrode panel200, the LC layer3interposed between the panels100and200, and a pair of polarizers12and22disposed on outer surfaces of the panels100and200.

Regarding the TFT array panel100, the gate line121including the gate electrode124and the end portion129, and the storage electrode line131including the storage electrodes133aand133bare formed on the substrate110. The gate insulating layer140, the semiconductor stripe151including the projection154, and the ohmic contacts161and165including the projection163are sequentially formed on the gate line121and the storage electrodes line131. The data line171including the source electrode173, the end portion179, and the drain electrode175are formed on the ohmic contacts161and165and the gate insulating layer140. The passivation layer180is formed on the data line171, the drain electrode175, and exposed portions of the semiconductor154. The third contact hole181, the first contact hole182, and the second contact hole185are provided at the passivation layer180and the gate insulating layer140. The pixel electrode191, the overpass83, the first contact assistants81, and the second contact assistant82are formed on the passivation layer180, and the alignment layer11is coated thereon.

In an exemplary embodiment of the common electrode panel200, the light blocking member220, the color filter230, the overcoat250, the common electrode270, and the alignment layer21are formed on the insulating substrate210. In an alternative exemplary embodiment of the LCD device, the columnar spacer320may be formed on the pixel electrode191, which is formed on the TFT array panel100. Additionally, the TFT array panel100may include the color filter230that are disposed under the passivation layer180and the common electrode panel200may not have the color filter230. In this exemplary embodiment, the overcoat250may be removed from the common electrode panel200.

The color filter230may be disposed between two adjacent data lines171and have a through-hole235through which the contact hole185pass through. The color filters230are not provided on peripheral areas provided with the end portions129and179of the signal lines121and171.

The color filter230may extend along a longitudinal direction to form a stripe and the edges of two adjacent color filters230may exactly match with each other on the data line171. However it is also contemplated that the color filters230may overlap each other and block the light leakage between two of the pixel electrodes191. Furthermore the color filters may also be spaced apart from each other.

In an exemplary embodiment, the color filter230may be disposed on the passivation layer180. However it is also contemplated that the passivation layer180may be omitted.

Although preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.