Liquid crystal display device and method for manufacturing the same

The present invention is for a liquid crystal display device having a patterned retarder enabling stereoscopic image display and a light reflector capable of improving luminous efficiency provided on a panel of the display device, and a manufacturing method thereof, the liquid crystal display device includes; first and second substrates arranged opposite each other, a light reflector on the first substrate, a first black stripe on the second substrate facing to the light reflector corresponding to the light reflector, a liquid crystal layer formed between the first and second substrates, a retarder provided on top of the second substrate, a reflector placed below the first substrate, and a light source positioned below the reflector.

Pursuant to 35 U.S.C. §119(a), this application claims the benefit of earlier filing date and right of priority to Korean Application 10-2010-0071652, filed on Jul. 23, 2010, the content of which is incorporated by reference herein in its entirety.

BACKGROUND

1. Field of the Invention

The present disclosure relates to a liquid crystal display device and, more particularly, to a liquid crystal display device including a patterned retarder enabling stereoscopic image display and a light reflector provided on a panel of the display device to improve luminous efficiency, as well as a manufacturing method thereof.

2. Discussion of the Related Art

Services for rapidly providing information over a high speed communication network have been developed from ‘listening and speaking’ services, such as provided by a telephone, to ‘viewing and listening’ multimedia type services using a digital terminal for rapidly processing text, voice and image data and, ultimately, to a three-dimensional stereoscopic information communication service for providing realistic stereoscopic viewing and entertainment, in order to implement ‘3-dimensionally viewing and enjoying above time and space.’

In general, the eyes form a three dimensional image based upon the principle of stereovision. Since two eyes have a disparity therebetween, that is, since two eyes are separated from each other by about 65 mm, the left eye and the right eye view slightly different images. A difference between images caused by such difference between the positions of the two eyes is referred to as ‘binocular disparity’. A three-dimensional image display device enables the left eye to view only an image for the left eye and the right eye to view only an image for the right eye according to such binocular disparity.

That is, the left and right eyes view two different two-dimensional images. Once these images are received by the retina and sent to the brain, they are processed into a three dimensional image by the brain, providing a sense of depth to the viewer. This capability is generally referred to as ‘stereography’ and a device having this capability is referred to as a stereoscopic image display device.

Hereinafter, with reference to the accompanying drawings, a liquid crystal display device of related art enabling stereoscopic display using glasses will be described.

FIG. 1is a schematic view illustrating a stereoscopic liquid crystal display device using glasses of related art.

Referring toFIG. 1, the liquid crystal display device of related art has a liquid crystal panel10independently displaying left and right (eye) images per a pixel basis, a retarder20having first and second different transmission axes that distinguish the above left images from the right images of the liquid crystal panel10and recognize corresponding images, respectively, and a pair of polarized glasses30outward of this panel, for example, worn by a user.

Here, the polarized glasses30have a left (eye) lens L and a right lens R having respective transmission axes, wherein the left lens L and the right lens R include polarized reflectors having the same first and second transmission axes as of the retarder20, respectively.

The retarder20is spatially divided and patterned to provide each pixel with first and second transmission axes and, in this case, is fixed to the liquid crystal panel10.

The retarder20is a patterned film to embody linear polarization in each direction of the first and second transmission axes.

Such a retarder20may be mounted on the liquid crystal panel10to spatially separate both the left and right images, and be patterned to embody two sets of vertical linear polarizations intersecting each other depending upon positions of the left and right images.

As shown in the drawings, if the left image is displayed in a polarizing direction at a right angle (90°) while displaying the right image in another polarizing direction at an angle of 0 degrees, a user wearing the polarized glasses30may recognize the right image transmitted through the first transmission axis through the left lens L and the left image transmitted through the second transmission axis through the right lens R, respectively, thereby perceiving a 3-dimensional image based on binocular disparity.

FIGS. 2A and 2Bare plan views illustrating a pixel region and a black-striped region in a structure having the foregoing patterned retarder.

If the structure has the retarder20, pixels for the left and right images are arranged adjacent to each other in the liquid crystal panel10, resulting in problems associated with crosstalk between two adjacent regions that display different images during 3D viewing.

In order to prevent crosstalk between left and right images, a black stripe21may be provided to each pixel P, as shown inFIG. 2B.

Reference number22not shown inFIG. 2A, refers to a wiring region on which gate wires or data wires are formed and which has a pixel region comprising respective pixels P defined in the wiring region.

A liquid crystal display device of related art enabling stereoscopic display in glasses mode has the following problems.

For such a liquid crystal display device described above, crosstalk occurs at adjacent parts of pixels, from which left and right images are displayed. In order to prevent such crosstalk, the display device usually has a black-striped structure.

The black stripe in the foregoing structure occupies a larger area than a black matrix or a wiring region present in a liquid crystal panel and effectively blocks passage of light therethrough. Therefore, due to the black stripe, an aperture ratio may be reduced, thus significantly deteriorating luminous efficiency.

BRIEF SUMMARY

A liquid crystal display device includes: first and second substrates arranged opposite each other; a light reflector on the first substrate; a first black stripe formed on the second substrate facing the light reflector corresponding to the light reflector; a liquid crystal layer formed between the first and second substrates; a retarder provided on a top of the second substrate; a reflector provided on a bottom of the first substrate; and a light source positioned below the reflector.

A method for manufacturing a liquid crystal display device, includes; positioning a light guide plate and arranging a light source at either side or both sides of the light guide plate, providing a reflector on the light guide plate, placing a first substrate on a top of the reflector and providing a light reflector on the first substrate, arranging a second substrate to face the first substrate, wherein the second substrate has a first black stripe at a predetermined location corresponding to the light reflector, forming a liquid crystal layer between the first and second substrates, and placing a retarder on the second substrate.

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

FIG. 3is a cross-sectional view illustrating a liquid crystal display device according to the present invention.

Referring toFIG. 3, the inventive liquid crystal display device comprises: first and second substrates100and150arranged opposite each other; a light reflector110provided on the first substrate100; a first black stripe160formed on the second substrate150opposite to the light reflector110at a predetermined site corresponding to the light reflector110; a liquid crystal layer170formed between the first and second substrates100and150; a retarder500placed above the second substrate150; a reflector410placed below the first substrate100; and a light source450positioned below the reflector410.

The inventive display device may further include first and second polarizers310and320placed at outer surfaces of the first and second substrates100and150, respectively.

The retarder500is divided into a left image display region510and a right image display region520, and may be a film type retarder patterned such that these display regions510and520have different light transmission axes or, optionally, may be an electrically switchable retarder in which the left and right regions are divided from each other by applied electric field. The latter directly emits light from the bottom of the display when no electric field is applied thereto. Since the switchable retarder requires applied voltage, a voltage source and a connector for the same may be provided.

Since an adjacent part between the left and right image display regions510and520in the retarder500is likely to suffer interference, it is preferable to allow this part to face the first black stripe160formed on the second substrate150. In this case, the first black stripe160is additionally formed or extended longer than a second black stripe (a general black matrix layer) corresponding to wirings provided on the first substrate100, thus possibly decreasing an aperture ratio of pixels.

In order to reduce a decrease in luminous efficiency owing to the first black stripe160, that is, to improve luminous efficiency, the inventive liquid crystal display device may further include the light reflector110formed on a top of the substrate100by utilizing any one of wirings that are mounted on the first substrate100to correspond to the first black stripe160.

The reflector410at the bottom of the display device (or referred to as ‘bottom reflector’) is reflected upward by the light reflector110, thus enabling the light to penetrate through the light reflector110adjacent to the reflector410.

In other words, as shown in the same figure, light directly emitted from the light guide plate400as well as the firstly transmitted light (solid line arrow) is combined with the secondly transmitted light (dash-dotted arrow), which was emitted from the light reflector110and then reflected again at the bottom reflector410, and pass through the first black stripe160. Therefore, it can be seen that the light reflector110enhances light transmission efficiency. Briefly, light transmission is indirectly conducted by double reflection through the light reflector110and the bottom reflector410, thus increasing luminous efficiency by at least 50%, compared to a structure without the light reflector.

In addition, the light reflector110does not require an alternative fabrication process, instead being patterned using the same material as is used for a gate line or data line during fabrication of a thin film transistor array on the first substrate100. Therefore, luminous efficiency may be enhanced without increasing the number of processing stages.

In general, a liquid crystal panel refers to a combination of a first substrate100, a second substrate150, a liquid crystal layer170formed therebetween, a thin film transistor array provided on the first substrate100(including the light reflector110described above) and a color filter array (including the first black stripe160described above) provided on the second substrate150.

Alternatively, the retarder500may be directly adhered to the second polarizer320, as shown inFIG. 3, or optionally, be placed inside the second substrate150.

The light source is arranged opposite to an edge part of the first substrate100. Here, the light guide plate400is provided below the reflector410, in order to guide light from the light source450upward.

Other than arrangement of the light source in an edge configuration, optionally, even when the light source may is positioned below the first substrate100in a drop configuration, luminous efficiency may be enhanced by arranging the light reflector110inside the first substrate100.

A gate line and a data line intersecting each other may be further provided on the first substrate110. Since the light reflector110receives applied common line signals, this component may be directly employed as a common line to which signals are applied.

Meanwhile, the light reflector110may be present on a layer of the first substrate100, on which the gate line or data line is present, and/or made of the same metal as is used for the gate line or data line.

In the case of a transverse electric configuration liquid crystal display device, a pixel electrode (see203inFIG. 6) and a common electrode (see205inFIG. 6) alternating each other may be present in the pixel region.

When the liquid crystal display device to be embodied is in a fringe field switching (FFS) mode, island type pixel electrode (see103inFIG. 4) and a common electrode pattern105having a plurality of branched patterns while overlapping the pixel electrode103, may be placed in the pixel region.

The light reflector110may be electrically connected to each of the common electrodes or be integrated with the same, depending upon mode of the liquid crystal display device.

The light reflector110may be fabricated in the form of at least one layer comprising at least one selected from aluminum (Al), aluminum alloy (e.g., AlNd), molybdenum (Mo), molybdenum alloy, chrome (Cr) and copper (Cu).

Other than the first black stripe described above, a second black stripe (see165inFIG. 5) to shield the gate line and the data line may be further included.

The following description will be given to concretely explain technical configurations of a liquid crystal display device according to the present invention, with respect to configuration modes of a liquid crystal panel of the display device.

FIG. 4is a plan view illustrating a liquid crystal display device according to an exemplary embodiment of the present invention.

Referring toFIG. 4, the liquid crystal display device according to the exemplary embodiment of the present invention comprises: a first substrate100; a gate line101and a data line102intersecting each other to define pixel regions; a thin film transistor placed at an intersection of the gate line101and the data line102; a light reflector110occupying a predetermined area (width) in the pixel region while being arranged in parallel to the gate line101; island type pixel electrode103present on an area within which the light reflector110is not present; and a common electrode pattern105overlapping the pixel electrode103and having branched patterns at the overlap site as well as a second contact hole104bin contact with the light reflector110.

Here, the pixel electrode103may be electrically connected to contact a drain electrode102bthrough a first contact hole104a.

Further, the common electrode pattern105may include a common electrode support pattern105awhich is electrically connected to the light reflector110via the second contact hole104b. The light reflector110receives applied common electrode signals at both ends of the first substrate100.

Meanwhile, the thin film transistor includes; a gate electrode101aprotruding from the gate line101, a source electrode102aprotruding from the data line102, the drain electrode102bbeing spaced from the source electrode, and a semiconductor layer (not shown) having two ends to which the source electrode102aand the drain electrode102bare connected, respectively.

The liquid crystal display device according to the foregoing exemplary embodiment employs an FFS configuration, wherein flat pixel electrode103electrically contact the light reflector110. In an FFS configuration, an electric field is formed between the branched patterns of the common electrode pattern105that overlap the pixel electrode103, thereby driving liquid crystals.

Although the foregoing exemplary embodiment describes formation of the light reflector110on a layer on which the gate line101is present, the light reflector110may instead be provided on a layer on which the data line is positioned. In such case, forming a different metal layer at an intersection between the gate line and the data line may enable light reflectors in adjacent pixel regions to be connected.

FIG. 5is a plan view illustrating a pixel region and an area on which a light reflector of the liquid crystal display device according to the present invention is formed.

Referring toFIG. 5, according to the foregoing exemplary embodiment, morphologies of an area on which the light reflector110is present and the remaining area of the gate line and the data line on which the second black stripe165is formed, are illustrated in plan view.

Here, the first black stripe160may correspond to the light reflector110.

The area of the light reflector110may be increased or decreased according to an interference area to be shielded.

The following description will be given to explain a liquid crystal display device according to another exemplary embodiment of the present invention.

FIG. 6illustrates the liquid crystal display device according to this exemplary embodiment of the present invention.

Referring toFIG. 6, the liquid crystal display device according to the foregoing exemplary embodiment of the present invention comprises: a first substrate200; a gate line201and a data line202intersecting each other to define pixel regions; a thin film transistor placed at an intersection between the gate line201and the data line202; a light reflector210occupying a predetermined area in a vertical direction in the pixel region while being arranged on a peripheral side of the pixel region; and pixel electrodes203and common electrodes205arranged alternately in the pixel region.

A pixel electrode support pattern203ais provided below the pixel electrodes203in a branched form, in order to connect these pixel electrodes203to one another. The pixel electrode support pattern203ais electrically connected to a drain electrode202bvia a first contact hole204a.

The common electrodes205are positioned on the same layer as the pixel electrodes203and are formed in a branched pattern such that each of the common electrodes is placed between adjacent pixel electrodes203. Moreover, the branched common electrodes205are integrated with the common electrode support pattern205aat a top end thereof.

The common electrode support pattern205ais electrically connected to the light reflector210via a second contact hole204band receives applied common electrode signals.

Meanwhile, as described above, the thin film transistor includes; a gate electrode201aprotruding from the gate line201, a source electrode202aprotruding from the data line202, the drain electrode202bspaced from the source electrode, and a semiconductor layer (not shown) having both ends, to which the source electrode202aand the drain electrode202bare connected, respectively.

The liquid crystal display device according to the foregoing exemplary embodiment adopts an In-Plane Switching (IPS) mode, wherein the common electrodes205and the pixel electrodes203are arranged alternately and, as shown in the figure, may be placed on the same layer by patterning the same transparent electrodes. Otherwise, the common electrodes and the pixel electrodes may be formed using different metals and arranged on different layers. In such case, a horizontal electric field may be formed between the pixel electrodes203and the common electrodes205, which in turn allows liquid crystals in the liquid crystal layer to be driven.

Hereinafter, preferred embodiments of a method for manufacturing a liquid crystal display device according to the present invention will be described in detail.

FIGS. 7A through 7Fare cross-sectional views illustrating a process of manufacturing a liquid crystal display device according to an exemplary embodiment of the present invention.

First, as shown inFIG. 7A, the process of manufacturing a liquid crystal display device according to the forgoing exemplary embodiment of the present invention comprises: depositing a first metal on a first substrate100and selectively removing the same, in order to form a gate line101in one direction and a gate electrode101aprotruding from the gate line101; and forming a light reflector110occupying a predetermined area (width) in a pixel region. The first metal used herein may include at least one selected from Al, Al alloy (e.g., AlNd), Mo, Mo alloy, Cr and Cu deposited in the form of a layer or a laminate comprising two or more layers.

Then, a gate insulating film (not shown) is formed throughout a front side of the first substrate100including the gate line101.

Next, as shown inFIG. 7B, a semiconductor layer (not shown) and a second metal are laminated onto the substrate, followed by selectively removing the same, in order to form a data line102intersecting the gate line101. In addition, both a ‘U’ shaped source electrode102aoverlapping the gate electrode101aand a drain electrode102bspaced from the source electrode are positioned on the samy layer with the data line102which intersects the gate line101.

Following this, as shown inFIG. 7C, an island type pixel electrode103is formed using a transparent electrode material in an area of the pixel region, from which the light reflector110is absent. Optionally, the pixel electrode103may overlap the light reflector110.

Subsequently, as shown inFIG. 7D, a protective film104, covering the entirety of the first substrate100, is applied, followed by selective removal thereof to form a first contact hole104aand a second contact hole104b.

Then, as shown inFIG. 7E, after depositing the transparent electrode material throughout the substrate and patterning the same, the pixel electrode103firstly overlaps the patterned substrate and a branched pattern is formed in the overlapping part. A common electrode pattern105is formed for connection to the light reflector110via the second contact hole104b. A common electrode support pattern105ais formed to extend from the common electrode pattern105in a vertical direction. The common electrode support pattern105ais connected to the light reflector110via the second contact hole104b. Further, a pixel electrode support pattern105bis formed to be electrically connected to the drain electrode102band a protruding part of the pixel electrode103via the first contact hole104a.

Therefore, the completed liquid crystal display device according to the above exemplary embodiment has the pixel electrode103connected to the drain electrode102bvia the first contact hole104aand the common electrode105connected to the light reflector110via the second contact hole104b, as shown inFIG. 7F.

FIGS. 8A through 8Eare cross-sectional views illustrating a process of manufacturing a liquid crystal display device according to another exemplary embodiment of the present invention.

First, as shown inFIG. 8A, the process of manufacturing a liquid crystal display device according to the foregoing exemplary embodiment of the present invention comprises: depositing a first metal on a first substrate and selectively removing the same, in order to form a gate line201in one direction and a gate electrode201aprotruding from the gate line201; and forming a light reflector210occupying a predetermined area (height) in a vertical direction in a pixel region. The first metal used herein may include at least one selected from Al, Al alloy (e.g., AlNd), Mo, Mo alloy, Cr and Cu deposited in the form of a layer or a laminate comprising two or more layers.

Then, a gate insulating film (not shown) is formed throughout a front side of the first substrate including the gate line201and the light reflector210.

Next, as shown inFIG. 8B, a semiconductor layer (not shown) and a second metal are laminated onto the substrate, followed by selective removal of the same, in order to form a data line202intersecting the gate line201. In addition, both a ‘U’ shaped source electrode202aoverlapping the gate electrode201aand a drain electrode202bspaced from the source electrode are on the same layer with the data line202which intersects the gate line201. The illustrated source electrode202amay have a specific shape formed to secure a desired channel length. However, shapes other than the above described U-shape, an L-shape for example, may be employed.

Following this, as shown inFIG. 8C, a protective film204covering the entirety of the first substrate is applied, followed by selective removal thereof to form a first contact hole204aand a second contact hole204b.

Subsequently, as shown inFIG. 8D, a plurality of pixel electrodes203and a plurality of common electrodes205are arranged alternately in the pixel region.

Here, a pixel electrode support pattern203ais provided below the pixel region to connect the pixel electrodes203in a branched form and is electrically connected to the drain electrode202bvia the first contact hole204a.

Furthermore, the common electrodes205are positioned on the same layer as the pixel electrodes203, and are formed in a branched pattern such that each of the common electrodes is placed between adjacent pixel electrodes203. Moreover, the branched common electrodes205are integrated with a common electrode support pattern205athat connects the common electrodes in a branched form at a top end thereof.

The common electrode support pattern205ais electrically connected to the light reflector210via a second contact hole204band receives applied common electrode signals.

Therefore, the completed liquid crystal display device according to the above exemplary embodiment is an IPS type liquid crystal display device comprising: the pixel electrode203connected to the drain electrode202band the pixel electrode support pattern203avia the first contact hole204a;and the common electrode205connected to the light reflector210and the common electrode support pattern205avia the second contact hole204b, as shown inFIG. 8E.

As such, the liquid crystal display device according to the present invention may be fabricated using a light reflector capable of functioning as a common electrode, as required. Additionally, without particular limitation to IPS or FES mode described above, a TN display device, or the like, may be embodied with the light reflector.

Among the foregoing methods for manufacturing a liquid crystal display device, respective processes of fabricating the remaining components other than the first substrate will be described in detail with reference toFIG. 3.

That is, after completing fabrication of the first substrate as described above, a second substrate including a first black stripe160, a second black stripe165and a color filter (not shown) is positioned facing the first substrate100, followed by formation of a liquid crystal layer170between the first and second substrates100and150, thereby producing a liquid panel.

The liquid panel having the first and second stripes160and165(seeFIG. 5) provided on the first and second substrates is mounted on top of the reflector410fabricated as described above.

Thereafter, a retarder500is provided on top of the second substrate150.

As described above, a liquid crystal display device and a manufacturing method thereof according to the present invention provide the following effects.

With regard to a structure comprising a retarder for stereoscopic image display, a light reflector is formed inside a liquid crystal panel in order to prevent an increase in aperture ratio when a black stripe is present between pixels emitting left and right images. Therefore, luminous efficiency may be enhanced by double reflection through a reflector as well as the light reflector positioned at the light source side on a lower part of the panel.

In addition, patterning the light reflector using the same metal as is used for the gate line or data line may improve luminous efficiency without requiring additional processes.

Moreover, the light reflector is provided on the same layer as the gate line and the data line, thus enabling slimness of the structure having the light reflector

The present invention is not restricted to the exemplary embodiments and the accompanying drawings described above, and those skilled in the art will appreciate that the present invention may cover substitutions, variations and/or modifications thereof without departing from the scope of the invention defined in the appended claims.