Display apparatus having innovative array substrate

An LCD array substrate for a transflective-type LCD includes an E-field reflecting section formed under a transmitting window that reflects light when an electric field is applied. A gate line, a gate electrode and a transparent electrode are formed on a substrate. A channel layer between source and drain electrodes and an E-field reflecting layer are formed on the gate electrode and the transparent electrode, respectively. Portions of a protecting layer are removed to form a contact hole disposed over the drain electrode, and a light-transmitting hole over the E-field reflecting layer. A pixel electrode that is electrically connected to the drain electrode through the contact hole, makes contact with the E-field reflecting layer through the light-transmitting hole.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application relies for priority upon Korean Patent Application No. 2005-53864 filed on Jun. 22, 2005, the contents of which are herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an improved display apparatus and, more particularly, to an array substrate for enhancing display quality and a method of manufacturing the array substrate.

DESCRIPTION OF THE RELATED ART

A liquid crystal display (LCD) apparatus may be classified as either a transmissive type LCD apparatus which employs a backlight assembly and hence can be used where there is no ambient light, or as a reflective type LCD apparatus which uses ambient light such as sunlight. However, the transmissive type LCD has higher power consumption increases due to the backlight assembly and its display quality may be lowered due to reflection of ambient light. The reflective-type LCD apparatus has lower power consumption, and higher display quality outdoors but cannot be used in a dark place. Therefore, active research is being performed on a transflective type LCD apparatus having merits of both the transmissive-type LCD apparatus and the reflective-type LCD apparatus.

The transflective-type LCD apparatus includes a backlight assembly and an LCD panel which displays an image by using ambient light and the light from the backlight assembly. The pixels of the LCD panel include a transmissive region and a reflective region. In the transmissive mode, the transflective-type LCD apparatus displays an image using light from the backlight assembly while in the reflective mode it displays an image by using ambient light. Therefore, the transflective-type LCD apparatus operates in the transmissive mode in a dark region and operates in the reflective mode in a well lit region. When operating in the reflective mode, a portion of light is reflected by the reflective region but the remaining portion of the light passes through the transmissive region. Therefore, the remaining portion of the light is leaked, resulting in lower luminance and poorer display quality.

SUMMARY OF THE INVENTION

The present invention provides a transflective-type LCD in which the display panel comprises a first substrate, a second substrate and a liquid crystal layer. The first substrate has a reflecting portion reflecting the ambient light in response to an electric field, and a transmitting portion transmitting the light generated by the backlight assembly. The light-reflecting layer includes an opening corresponding to a transmitting window. An E-field reflecting section is formed under the transmitting window that reflects light when an electric field is applied. A gate line, a gate electrode and a transparent electrode are formed on the substrate. A channel layer and an E-field reflecting layer are formed on the gate electrode and the transparent electrode, respectively. A data line is formed, and source and drain electrodes are formed on the channel layer. A protecting layer is formed on the substrate to cover the data line, the source electrode and the drain electrode. Portions of the protecting layer are removed to form a contact hole disposed over the drain electrode, and a light-transmitting hole over the E-field reflecting layer. A pixel electrode that is electrically connected to the drain electrode through the contact hole, makes contact with the E-field reflecting layer through the light-transmitting hole. A light-reflecting layer having an opening corresponding to a transmitting window is formed over the E-field reflecting layer.

DESCRIPTION

Example Embodiment 1 of a Display Panel Assembly

FIG. 1is an exploded perspective view illustrating a display panel assembly according to an example embodiment of the present invention.FIG. 2is a plan view illustrating a pixel of the display panel assembly inFIG. 1, andFIG. 3is a cross-sectional view taken along a line I-I′ inFIG. 2. Referring toFIGS. 1 to 3, a display panel assembly includes a first substrate100, a second substrate200, a liquid crystal layer300, a first polarizing plate10, a first retardation film20, a second retardation film30, a second polarizing plate40and a light-refracting sheet50. The display panel displays an image by using light provided by a backlight assembly or ambient light. The first polarizing plate10is disposed under the first substrate100. The first retardation film20is disposed between the first polarizing plate10and the first substrate100. The second polarizing plate40is disposed over the second substrate200. The second retardation film30is disposed between the second polarizing plate40and the second substrate200. The light-refracting sheet50is disposed on the second polarizing plate40.

The first substrate100includes a first transparent substrate110, a data line DL, a gate line GL, a storage electrode (not shown), a gate insulation layer120, a thin-film transistor TFT, a protecting layer130, a pixel electrode140, a light-reflecting layer150, a connecting layer155, a transparent electrode160, an electric field (E-field) reflecting layer170and a first alignment layer (not shown).

First substrate100has a plate-shape. First transparent substrate110is of an optically transparent material such as glass, quartz, etc. A plurality of gate lines GL are formed on the first transparent substrate110. Gate line GL extends in a first direction. A storage electrode which assists the pixel electrode in maintaining a pixel voltage is formed simultaneously with gate line GL and extends in the same direction as that of gate line GL. Gate insulation layer120is formed on first transparent substrate110such that gate insulation layer120covers gate line GL and the storage electrode. Thin-film transistor TFT includes a gate electrode G, a source electrode S, a drain electrode D, a channel layer C and an ohmic contact layer O. Gate electrode G extends from gate line GL along a second direction that is substantially perpendicular to the first direction. Gate insulation layer120is disposed on gate electrode G, and channel layer C is disposed on gate insulation layer120such that channel layer C crosses gate electrode G. Ohmic contact layer O is disposed on channel layer C. Ohmic contact layer O reduces contact resistance between channel layer C and the drain and source electrodes. The source electrode S and the drain electrode D are disposed on the ohmic contact layer O such that the source electrode S and the drain electrode D are spaced apart from each other.

A plurality of data lines DL are formed on gate insulation layer130and extend in second direction. Source electrode S extends from data line DL along the first direction. Protecting layer130is formed on gate insulation layer120such that the protecting layer130covers thin-film transistor TFT and data lines DL. For example, an organic layer may be employed as the protecting layer130which is thicker than gate insulation layer120. Protecting layer130has an embossed patterns formed on its surface. Protecting layer130includes a contact hole132and a light-transmitting hole134. Pixel electrode140is electrically connected to drain electrode D of thin-film transistor TFT through contact hole132. Light-transmitting hole134corresponds to transmitting window152.

Pixel electrode140is formed on the protecting layer130and is disposed in a pixel region defined by each gate line GL and each of the data line DL. Pixel electrode140is electrically connected to the drain electrode D to receive a pixel voltage from the drain electrode D.

Pixel electrode140makes contact with E-field reflecting layer170through light-transmitting hole134. Pixel electrode140has an embossed patterns in the region disposed toward protecting layer130, and a flat surface at the region disposed toward the E-field reflecting layer170. Pixel electrode140includes an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc. The optically transparent and electrically conductive layer may be patterned through a photolithography process to form pixel electrode140.

Light-reflecting layer150is formed on pixel electrode140except for the light-transmitting hole134. The light-reflecting layer150includes, for example, metal for reflecting light. The light-reflecting layer150includes, for example, aluminum (Al), aluminum neodymium (AlNd), etc. Light-reflecting layer150includes a reflecting portion that reflects a portion of ambient light, and the transmitting window152that transmits a portion of light from the backlight assembly. The reflecting portion corresponds to a region where the light-reflecting layer150is formed, and the transmitting window152corresponds to a region where the light-reflecting layer150is not formed. Preferably, an area of the transmitting window152is about 60% to about 70% of a unit pixel area.

Connecting layer155is disposed between light-reflecting layer150and pixel electrode140. Connecting layer155reduces deterioration of surface characteristics that may be induced when the light-reflecting layer150makes contact with pixel electrode150. The connecting layer155includes, for example, molybdenum tungsten (MoW). Transparent electrode160is correspondingly formed on gate insulation layer120to the light-transmitting hole134. Transparent electrode160includes an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc., the same material as that of pixel electrode140.

When a driving voltage provided from an external device is applied to the transparent electrode160, an electric field is generated between pixel electrode140and the transparent electrode. For example, the electric field generated between pixel electrode140and transparent electrode160is in a range of about 10 kV/cm to about 100 kV/cm, and a frequency is in a range of about 0.1 kHz to about 10 kHz.

The driving voltage applied to transparent electrode160is different from the pixel voltage applied to pixel electrode140. A voltage difference between the driving voltage and the pixel voltage may be a direct current (DC) voltage. Alternatively, the voltage difference between the driving voltage and the pixel voltage may be an alternating current (AC) voltage.

The E-field reflecting layer170is disposed between pixel electrode140and the transparent electrode160. The E-field reflecting layer170is correspondingly disposed to the light-transmitting hole134. The E-field reflecting layer170reflects a portion of ambient light, when the electric field is generated between pixel electrode140and the transparent electrode160. In other words, the electric field generated between pixel electrode140and the transparent electrode160changes a dielectric constant of the E-field reflecting layer170to enhance reflectivity.

E-field reflecting layer170includes an insulator material or a semiconductor material. The semiconductor material is preferable. Examples of the semiconductor material include silicon (Si), compound semiconductor, etc. Examples of the compound semiconductor include a compound of group III and group V such as gallium arsenide (GaAs), indium phosphorous (InP), gallium phosphorous (GaP), etc., a compound of group II and group VI such as cadmium sulfide (CdS), zinc telluride (ZnTe), etc., and a compound of group IV and group VI such as lead sulfide (PbS), etc. For example, the E-field reflecting layer170includes gallium arsenide (GaAs).

E-field reflecting layer170has a thickness of about 50 angstroms to about 500 angstroms, so that light generated by the backlight assembly may pass through the E-field reflecting layer170. Preferably, E-field reflecting layer170has a thickness of about 100 angstroms to about 200 angstroms.

A first alignment layer is formed on pixel electrode140such that the first alignment layer covers light-reflecting layer150. The first alignment layer includes a plurality of first alignment grooves (not shown) for aligning liquid crystal molecules along a specific direction.

Second substrate200is disposed facing first substrate100. Second substrate200includes a second transparent substrate210, a light blocking layer220, a color filter230, a common electrode240and a second alignment layer (not shown). Second transparent substrate210includes an optically transparent material such as glass or quartz, etc., the same material as that of the first transparent substrate110. Second transparent substrate210has a smaller size than that of the first transparent substrate110. Light blocking layer220is formed on second transparent substrate210. Light blocking layer220is disposed over thin-film transistor TFT, data line DL and gate line GL, so that the light blocking layer covers the thin-film transistor TFT, the data line DL and gate line GL to prevent the thin-film transistor TFT, the data line DL and gate line GL from being shown.

Color filter230is formed on the second transparent substrate210. The color filter230is disposed over pixel electrode140. The color filter may cover edge portions of the light blocking layer220. Color filter230includes a red color filter that selectively transmits red light, a green color filter that selectively transmits green light, and a blue color filter that selectively transmits blue light.

Common electrode240is formed on second transparent substrate210having light blocking layer220and color filter230formed thereon to cover light blocking layer220and color filter230. Common electrode240receives a reference voltage. Common electrode240includes an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc.

Second alignment layer is formed on common electrode240. The second alignment layer includes a plurality of second alignment grooves (not shown) for aligning liquid crystal molecules in a specific direction.

Liquid crystal layer300is disposed between the first substrate100and the second substrate200. When the pixel voltage is applied to pixel electrode140, and the reference voltage is applied to the common electrode240, the arrangement of liquid crystal molecules of the liquid crystal layer300is altered to change optical transmissivity of ambient light or light generated by the backlight assembly. As a result, an image is displayed.

First and second polarizing plates10and40polarize light. For example, the first polarizing plate10has an optical axis that is substantially perpendicular to an optical axis of the second polarizing plate40. First and second retardation films20and30alter the phase of light by an amount of a quarter wavelength. Alternatively, the first and second retardation films20and30alter the phase of light by an amount of a half wavelength. The first retardation film has a first retardation axis and the second retardation film has a second retardation axis that is substantially perpendicular to the first retardation axis.

The light refracting sheet50is disposed on the second polarizing plate40. The light refracting sheet50refracts light that passes through the liquid crystal layer300to enhance front-view luminance. InFIGS. 1 and 3, the light refracting sheet50is disposed on the second polarizing plate40. Alternatively, the light refracting sheet50may be disposed between the second polarizing plate40and the second retardation film30.

The way reflectivity is enhanced by the electric field between pixel electrode140and the transparent electrode160will now be explained in detail. E-field reflecting layer170includes an insulator material or a semiconductor material. E-field reflecting layer170contains a plurality of electrons and a plurality of holes. The electrons and holes may be rearranged by an electric field. When an electric field is generated between pixel electrode140and the transparent electrode160, the electric field alters an arrangement of electrons and holes to change a dielectric constant of the E-field reflecting layer170. As a result, reflectivity of the E-field reflecting layer170is changed.

The reflectivity of the E-field reflecting layer170may be expressed as the following Expression 1.
R=Ro{1+C(F1/3/ω2)},
wherein ‘R’ represents a reflectivity of E-field reflecting layer170when an electric field is applied thereto, ‘R0’ represents the reflectivity of E-field reflecting layer170when no electric field is applied thereto, ‘C’ represents a constant relating to the material of E-field reflecting layer170, ‘F’ is the strength of the electric field, ‘ω’ represents the angular frequency of the electric field.

As shown in Expression 1, the reflectivity ‘R’ of E-field reflecting layer170is proportional to F1/3and inversely proportional to ω2. In other words, when electric field ‘F’ increases, the reflectivity ‘R’ of the E-field reflecting layer170also increases. On the contrary, when the angular frequency ‘ω’ of the electric field increases, the reflectivity ‘R’ of E-field reflecting layer170decreases.

FIG. 4is an enlarged view illustrating a portion ‘II’ inFIG. 3. Referring toFIG. 4, the light refracting sheet50includes a plurality of prisms52refracting light that originates from the display panel. The prisms have a saw tooth cross-sectional shape. For example, a cross-sectional shape of the prisms has a saw tooth shape with convex upper portions. Even though the prism having a saw tooth shape is disclosed inFIG. 4, the prism may have other shapes. For example, the prism may have triangular shape.

The path of light passing through the display panel assembly will now be explained.FIGS. 5 and 6are conceptual views illustrating light paths when no electric field is applied to the liquid crystal layer of the display panel assembly inFIG. 1. In detail,FIG. 5shows light paths when no electric field is applied to both of the liquid crystal layer and the E-field reflecting layer, andFIG. 6shows light paths when no electric field is applied to the liquid crystal layer, but an electric field is applied to the E-field reflecting layer. Referring toFIG. 5, a portion of ambient light ‘a’ passes through the second polarizing plate40to be polarized along a third direction. The ambient light ‘a’ polarized along the third direction passes through the second retardation film30to have a phase change by a quarter wavelength. As a result, the ambient light ‘a’ is circularly polarized to rotate along a counterclockwise direction.

The ambient light ‘a’ that is circularly polarized to rotate along a counterclockwise direction passes through liquid crystal layer300to have a phase change by a quarter wavelength. As a result, the ambient light ‘a’ is linearly polarized to oscillate along a fourth direction that is substantially perpendicular to the third direction. The ambient light ‘a’ that is linearly polarized is reflected by light-reflecting layer150.

The ambient light ‘a’ reflected by light-reflecting layer150passes through the liquid crystal layer300to have a phase change by a quarter wavelength. As a result, the ambient light ‘a’ is circularly polarized to rotate along a counterclockwise direction. The ambient light ‘a’ that is circularly polarized to rotate along a counterclockwise direction passes through the second retardation film30to have a phase change by a quarter wavelength to be linearly polarized to oscillate along the third direction. The ambient light ‘a’ that is linearly polarized to oscillate along the third direction passes through second polarizing plate40without any blocking.

On the other hand, a portion of light ‘b’ generated by the backlight assembly passes through the first polarizing plate10to be linearly polarized along the fourth direction. The light ‘b’ polarized along the fourth direction passes through the first retardation film20to have a phase change by a quarter wavelength. As a result, the light ‘b’ is circularly polarized to rotate along a clockwise direction. The light ‘b’ that is circularly polarized to rotate along a clockwise direction directly passes through the E-field reflecting layer170and enters the liquid crystal layer300having no electric field applied thereto. The light ‘b’ entering the liquid crystal layer300passes through the liquid crystal layer300to have a phase change by a quarter wavelength. As a result, the light ‘b’ is linearly polarized along the third direction.

The light ‘b’ that is linearly polarized along the third direction passes through the second retardation film30to be circularly polarized to rotate along a clockwise direction, and the light ‘b’ that is circularly polarized passes through the second polarizing plate40to be linearly polarized along the third direction. As a result, an image is displayed.

Referring toFIG. 6, a portion of ambient light ‘c1’, which advances toward the light-reflecting layer150undergoes substantially the same process to display an image as the ambient light ‘a’ inFIG. 5. Thus, any further explanation will be omitted. A portion of ambient light ‘c2’, which is incident toward the transmitting window152, is reflected by the E-field reflecting layer170and the ambient light ‘c2’ undergoes substantially the same process as the light ‘a’ inFIG. 5to display an image. As described above, when the ambient light, which is incident toward the transmitting window152to be leaked, is reflected by the E-field reflecting layer170, a high luminance level may be obtained to display the image.FIGS. 7 and 8are conceptual views illustrating light paths when an electric field is applied to a liquid crystal layer of the display panel assembly inFIG. 1. In detail,FIG. 7corresponds to light paths when an electric field is not applied to the E-field reflecting layer and an electric field is applied to the liquid crystal layer, andFIG. 8corresponds to a light path when an electric field is applied to both the E-field reflecting layer and the liquid crystal layer.

Referring toFIG. 7, when a portion of ambient light ‘d’ passes through the second polarizing plate30, the portion of ambient light ‘d’ is polarized along a third direction. The portion of ambient light ‘d’ polarized along the third direction passes through the second retardation film30to have a phase change by a quarter wavelength. As a result, the portion of ambient light ‘d’ that passes through the second retardation film30is circularly polarized to rotate along a counterclockwise direction.

The portion of ambient light ‘d’ that is circularly polarized to rotate along a counterclockwise direction passes through the liquid crystal layer300without a phase change. The portion of ambient light ‘d’ that passes through liquid crystal layer300without a phase change is reflected by light-reflecting layer150to have a phase change by a half wavelength. As a result, the portion of ambient light ‘d’ that is reflected by light-reflecting layer150is circularly polarized to rotate along a clockwise direction. The portion of ambient light ‘d’ that is circularly polarized to rotate along a clockwise direction passes through liquid crystal layer300without a phase change. The portion of ambient light ‘d’ that passes through liquid crystal layer300without a phase change passes through second retardation film30to have a phase change by a quarter wavelength to be polarized along a fourth direction. The portion of ambient light ‘d’ that is polarized along a fourth direction is blocked by the second polarizing plate40. As a result, no image is displayed through the portion of ambient light ‘d’.

On the contrary, a portion of light ‘e’ generated from the backlight assembly passes through first polarizing plate10to be polarized along the fourth direction. The portion of light ‘e’ that is polarized along the fourth direction passes through the first retardation film20to have a phase change by a quarter wavelength. As a result, the portion of light ‘e’ that passes through first retardation film20is circularly polarized to rotate along a clockwise direction. The portion of light ‘e’ that is circularly polarized to rotate along a clockwise direction passes through E-field reflecting layer170and then passes through the liquid crystal layer300to which an electric field is applied without change.

The portion of light ‘e’ that passes through liquid crystal layer300passes through second retardation film30. The portion of light ‘e’ that passes through second retardation film30is polarized to have a phase change by a quarter wavelength. As a result, the portion of light ‘e’ that passes through second retardation film30is linearly polarized along the fourth direction. The portion of light ‘e’ that is linearly polarized along the fourth direction is blocked by second polarizing plate40. Therefore, no image is displayed by the portion of light ‘e’.

Referring toFIG. 8, a portion of ambient light f1, which advances toward light-reflecting layer150has substantially the same light path as the portion of light ‘d’ inFIG. 7. Therefore, the portion of ambient light f1does not display an image. The portion of ambient light f2, which advances toward the transmitting window152, is reflected by E-field reflecting layer170. Therefore, the portion of ambient light f2has substantially the same path as the light ‘d’ inFIG. 7. As a result, the portion of ambient light f2does not display an image.

According to the present embodiment, when pixel electrode140and transparent electrode160apply an electric field to the E-field reflecting layer170disposed between pixel electrode140and transparent electrode160, pixel electrode140reflects ambient light to enhance luminance.

Example Embodiment 2 of a Display Panel Assembly

FIG. 9is a cross-sectional view illustrating a portion of a display panel assembly according to another example embodiment of the present invention. The display panel assembly of the present embodiment is the same as in the previous example embodiment except for a protecting layer, a pixel electrode, a first transparent electrode, a second transparent electrode and an E-field reflecting layer. Thus, the same reference numerals will be used to refer to the same or like parts as those described in previous example embodiment and any further explanation will be omitted.

Referring toFIG. 9, a display panel assembly includes a first substrate100, a second substrate200, a liquid crystal layer300, a first polarizing plate10, a first retardation film20, a second retardation film30, a second polarizing plate40and a light refracting sheet50. The display panel assembly displays an image by using ambient light and light generated by a backlight assembly.

First substrate100includes a first transparent substrate110, a data line DL, a gate line GL, a storage electrode, a gate insulation layer120, a thin-film transistor TFT, a protecting layer130, a pixel electrode140, a reflecting layer150, a connecting layer155, a first transparent electrode180, a second transparent electrode185, an E-field reflecting layer190and a first alignment layer.

Protecting layer130is formed on gate insulation layer120such that the protecting layer130covers the thin-film transistor TFT and the data line DL. For example, an organic layer may be employed as the protecting layer130, and the protecting layer130is thicker than gate insulation layer120. Protecting layer130has an embossed pattern formed on its surface. Protecting layer130includes a contact hole132. Drain electrode D of thin-film transistor TFT is electrically connected to pixel electrode140through the contact hole132. Pixel electrode140is formed on the protecting layer130. Pixel electrode140is disposed in a pixel region defined by each of gate lines GL and each of the data lines DL. Pixel electrode140is electrically connected to the drain electrode D to receive a pixel voltage from the drain electrode D.

Pixel electrode140includes an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc. An optically transparent and electrically conductive layer may be patterned through a photolithography process to form pixel electrode140.

Light-reflecting layer150is formed on pixel electrode140. Light-reflecting layer150includes an opening corresponding to the transmitting window152. The light-reflecting layer150includes, for example, metal for reflecting light. The light-reflecting layer150includes, for example, aluminum (Al), aluminum neodymium (AlNd), etc. Light-reflecting layer150includes a reflecting portion that reflects a portion of ambient light, and the transmitting window152that transmits a portion of light generated by the backlight assembly. The reflecting portion corresponds to a region where the light-reflecting layer150is formed, and the transmitting window152corresponds to a region where the light-reflecting layer150is not formed. Preferably, an area of the transmitting window152is about 60% to about 70% of a unit pixel area.

First transparent electrode180is formed on gate insulation layer120so as to correspond to light-transmitting hole152. First transparent electrode180has a larger size than the light-transmitting hole152. First transparent electrode180includes an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc., the same material as that of pixel electrode140. The first transparent electrode180receives a first driving voltage from an external voltage generating device (not shown).

E-field reflecting layer190is correspondingly disposed to the light-transmitting window152. The E-field reflecting layer190is formed on gate insulation layer120such that the E-field reflecting layer190covers the first transparent electrode180.

Second transparent electrode185is covered by the protecting layer140. The second transparent electrode185includes an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc., the same material as that of pixel electrode140. Second transparent electrode185receives a second driving voltage that is different from the first driving voltage from an external voltage from an external voltage generating device (not shown). The first and second driving voltages applied to the transparent electrodes180and185, respectively apply an electric field to E-field reflecting layer190. For example, the electric field applied to E-field reflecting layer190is in the range of about 10 kV/cm to about 100 kV/cm, and a frequency of the electric field is in the range of about 0.1 kHz to about 10 kHz.

When an electric field is generated between the first and second transparent electrodes180and185or applied to the E-field reflecting layer190, the E-field reflecting layer190reflects a portion of ambient light. E-field reflecting layer190includes an insulator material or a semiconductor material, but semiconductor material is preferable. Examples of the semiconductor material include silicon (Si), compound semiconductor, etc. The E-field reflecting layer190has a thickness of about 50 angstroms to about 500 angstroms. Preferably, the E-field reflecting layer190has a thickness of about 100 angstroms to about 200 angstroms.

According to the present embodiment, E-field reflecting layer190is disposed between first and second transparent electrodes180and185, and first and second transparent electrodes180and185apply an electric field to E-field reflecting layer190for reflecting ambient light. As a result, luminance of the display panel assembly is enhanced.

Example Embodiment of a Display Apparatus

FIG. 10is an exploded perspective view illustrating a display apparatus according to an example embodiment of the present invention. A display panel assembly of a display apparatus according to the present example embodiment is substantially the same as the example embodiment inFIGS. 1 to 8. Therefore, further explanation will be omitted. Referring toFIG. 10, a display apparatus according to the present example embodiment includes a display panel assembly, a printed circuit board400, a flexible printed circuit450, a backlight assembly and a top chassis900. The display panel assembly displays an image by using ambient light and light generated by the backlight assembly. The display panel assembly includes a first substrate100having a thin-film transistor TFT, a second substrate200having a color filter, and liquid crystal layer300disposed between the first and second substrates100and200. For example, a driving circuit is formed on side portions of the first substrate100.

Additionally, the display panel assembly further includes a first polarizing plate10, a second polarizing plate40, a first retardation film20, a second retardation film30and a light refracting sheet50. The first polarizing plate10is disposed under the first substrate100. First retardation film20is disposed between the first polarizing plate10and the first substrate100. Second retardation film30, second polarizing plate40and light refracting sheet50are disposed over the second substrate in sequence. Printed circuit board400includes a driving circuit unit processing an image signal. The driving circuit unit converts an external image signal into a first driving signal controlling a driving chip112. Flexible printed circuit450electrically connects printed circuit board400to first substrate100to transfer the first driving circuit generated by printed circuit board400to driving chip112of first substrate100. Driving chip112generates a second driving signal controlling the thin-film transistor TFT by using the first driving signal. Flexible printed circuit450may be bent so that the printed circuit board400may be disposed under the display panel assembly.

The backlight assembly includes a receiving container500, a light-generating unit600, a light-guide plate700, a light-reflecting plate750and optical sheets800. The receiving container500includes a bottom plate510and sidewalls520protruded from edge portions of the bottom plate510. The bottom plate510and the sidewalls520define a receiving space to receive the light-generating unit600, the light-guide plate700, the light-reflecting plate750, the optical sheets800and the display panel assembly. One of the sidewalls520, which faces the flexible printed circuit600, includes a recessed portion522. The flexible printed circuit600may be bent through the recessed portion522.

Light-generating unit600is disposed such that the light-generating unit600is disposed near one of the sidewalls520. The light-generating unit600receives electric power from an external power supply to generate light. Light-generating unit600includes, for example, light-emitting diodes. The light-emitting diodes are disposed on a driving substrate. The light-emitting diodes receive electric power from the driving substrate to provide the light-guide plate700with light. Alternatively, the light-generating unit600may include a cold cathode fluorescent lamp (CCFL) having a rod-shape. Light-guide plate700is disposed in the receiving container500such that the light-generating unit600faces a side face of the light-guide plate700. Light generated by the light-generating unit600enters the light-guide plate700through a the side face of light-guide plate700and exits from light-guide plate700through the upper face of the light-guide plate700to enter the display panel assembly. Light-reflecting plate750is disposed in the receiving container500. Light-reflecting plate750is disposed under light-guide plate700and reflects light that exits light-guide plate700through its lower face toward light-guide plate700.

Optical sheets800are disposed over the backlight assembly to enhance optical characteristics of light generated by the backlight assembly. The optical sheets800include a diffusion sheet810for diffusing light in order to enhance luminance uniformity, and a prism sheet820for enhancing a front-view luminance. The top chassis900surrounds edge portions of the display panel assembly, and is combined with the sidewalls of the receiving container500to fasten the display panel assembly to the receiving container500. The top chassis900protects the display panel assembly, which is brittle, from external impacts and prevents the display panel assembly from being separated from the receiving container500.

Example Embodiment of Method of Manufacturing an Array Substrate

FIGS. 11A to 11Eare cross-sectional views illustrating a method of manufacturing an array substrate according to an example embodiment of the present invention. In detail,FIG. 11Ashows a process of forming the gate insulation layer to cover the gate line and gate electrode.FIG. 11Bshows a process of forming the channel layer, the transparent electrode and the E-field reflecting layer.FIG. 11Cshows a process of forming data line, the source electrode and the drain electrode.FIG. 11Dshows a process of forming a protecting layer and removing a portion of the protecting layer.FIG. 11Eshows a process of forming the pixel electrode and the light-reflecting layer150.

Referring toFIG. 11A, the gate electrode G is formed on the transparent substrate110. Gate electrode G is simultaneously formed with the gate line (not shown). Gate electrode G protrudes from the gate line. Then, gate insulation layer120is formed to cover gate electrode G and the gate line. Referring toFIG. 11B, transparent electrode160is formed on gate insulation layer120. Transparent electrode160includes an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc. For example, the transparent electrode160is patterned through a photolithography process.

Then, E-field reflecting layer170is formed on the transparent electrode160. For example, E-field reflecting layer170is formed such that it covers transparent electrode160and has a thickness of no more than about 500 angstroms. E-field reflecting layer170includes, for example an insulator material or a semiconductor material such as silicon (Si), compound semiconductor, etc. When E-field reflecting layer170includes a semiconductor material, it may be formed simultaneously with channel layer C. Channel layer C is formed on gate insulation layer120such that it crosses gate electrode G. An ohmic contact layer O including a highly concentrated dopant is formed on the channel layer C.

Referring toFIG. 1C, the source electrode S and the drain electrode D are formed such that the source electrode S and the drain electrode D cover portions of the ohmic contact layer O. The source electrode S and the drain electrode D are simultaneously formed with the data line (not shown) formed on gate insulation layer120. Source electrode S and drain electrode D are formed such that the source electrode S and the drain electrode D are spaced apart from each other. Then, ohmic contact layer O exposed between the source electrode S and the drain electrode D is etched, for example by plasma. As a result, the ohmic contact layer O is separated into two pieces. Then, the thin-film transistor TFT including gate electrode G, the source electrode S, the drain electrode D, the channel layer C and the ohmic contact layer O is completed.

Referring toFIG. 1D, protecting layer130is formed on gate insulation layer120such that protecting layer130covers the thin-film transistor TFT and E-field reflecting layer170. Protecting layer130is formed such that a thickness of the protecting layer130is thicker than that of gate insulation layer120. Then, portions of the protecting layer130are removed, for example by plasma to form the contact hole132and the light-transmitting hole134. The contact hole132is disposed over the drain electrode D, and the light-transmitting hole134is disposed over the E-field reflecting layer170.

Referring toFIG. 11E, pixel electrode140is formed on the protecting layer130. Pixel electrode140includes an optically transparent and electrically conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc., the same material as that of the transparent electrode160. Pixel electrode140is electrically connected to the drain electrode D through the contact hole132. Pixel electrode140is also formed on the E-field reflecting layer170exposed through the light-transmitting hole134. Then, connecting layer155is formed on pixel electrode140except for a region corresponding to the light-transmitting hole134. The connecting layer155includes, for example, molybdenum tungsten alloy (MoW). Then, reflecting layer150is formed on connecting layer155. Reflecting layer150includes metal in order to reflect ambient light. Reflecting layer150includes, for example, aluminum (Al) or aluminum neodymium (AlNd).

Having described of the present invention and its advantages, it is noted that various changes, substitutions and alterations can be made by those skilled in the art without however departing from the spirit and scope of the invention.