KR20030058200A - Liquid crystal display - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to remove partial areas of color filters passing thin film transistors for equalizing the light leakage current generated from the thin film transistors, thereby preventing the generation of the luminance difference among liquid crystal cells of red, green and blue pixels and the flickering of the liquid crystal cells of green pixels. CONSTITUTION: A liquid crystal display device includes a lower substrate formed with thin film transistors(TFT) formed on intersections between gate and data lines(2,4) and pixel electrodes(14) connected to drain electrodes(12) of the thin film transistors, and an upper substrate having black matrixes formed on areas corresponding to the gate and data lines and the thin film transistors, and color filters(73) formed in unit pixels except areas('a') passing the thin film transistors.

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and in particular, the photo leakage current of a thin film transistor provided for each liquid crystal cell is red (R-red), green (G-green), and blue (B). The present invention relates to a liquid crystal display device for preventing deepening of flicker in a liquid crystal cell of a specific pixel as the liquid crystal cell of a blue pixel is different.

In general, a liquid crystal display device displays a desired image by individually supplying data signals according to image information to liquid crystal cells arranged in a matrix form, and adjusting a light transmittance of the liquid crystal cells. to be.

Accordingly, a liquid crystal display device includes: a liquid crystal panel in which liquid crystal cells forming a pixel unit are arranged in an active matrix form; A driver integrated circuit (IC) for driving the liquid crystal cells is provided.

In this case, the liquid crystal panel includes a color filter substrate and a thin film transistor array substrate facing each other, and a liquid crystal layer filled in spaced intervals between the color filter substrate and the thin film transistor array substrate.

On the thin film transistor array substrate of the liquid crystal panel, a plurality of data lines for transmitting the data signal supplied from the data driver integrated circuit to the liquid crystal cells and a scan signal supplied from the gate driver integrated circuit for the liquid crystal cells are provided. The plurality of gate lines are orthogonal to each other, and liquid crystal cells are defined at each intersection of these data lines and the gate lines.

In this case, the gate driver integrated circuit sequentially supplies scan signals to a plurality of gate lines, so that the liquid crystal cells arranged in a matrix form are sequentially selected one by one, and a data driver is provided in the selected one line of liquid crystal cells. The data signal is supplied from the integrated circuit.

Meanwhile, a common electrode and a pixel electrode are formed on opposite inner surfaces of the color filter substrate and the thin film transistor array substrate to apply an electric field to the liquid crystal layer. In this case, the pixel electrode is formed for each liquid crystal cell on the thin film transistor array substrate, while the common electrode is integrally formed on the entire surface of the color filter substrate. Therefore, by controlling the voltage applied to the pixel electrode in a state where a voltage is applied to the common electrode, it is possible to individually control the light transmittance of the liquid crystal cells.

As described above, in order to control the voltage applied to the pixel electrode for each liquid crystal cell, a thin film transistor used as a switching element is formed in each liquid crystal cell.

In liquid crystal cells in which a scan signal is supplied to a gate electrode of the thin film transistor through a gate line, a conductive channel is formed between the source electrode and the drain electrode of the thin film transistor, and is supplied to the source electrode of the thin film transistor through the data line. The data signal is supplied to the pixel electrode via the drain electrode of the thin film transistor.

The liquid crystal display as described above will be described in detail with reference to the accompanying drawings.

First, FIG. 1 is an exemplary view showing a general planar configuration of a liquid crystal cell of red (R), green (G), and blue (B) pixels of a liquid crystal display.

Referring to FIG. 1, the lower substrate may include pixels formed at the intersections of the red, green, and blue data lines 2 and the gate lines 4, respectively. And a pixel electrode 14 connected to the drain electrode 12 of the thin film transistor TFT.

The source electrode 8 of the thin film transistor TFT is connected to the data line 2, and the gate electrode 10 is connected to the gate line 4.

The drain electrode 12 of the thin film transistor TFT is connected to the pixel electrode 14 through the drain contact hole 16.

The thin film transistor TFT has an active layer forming a conductive channel between the source electrode 8 and the drain electrode 12 by a scan signal supplied to the gate electrode 10 through the gate line 4 (on the drawing). Not shown).

As such, the active layer forms a conductive channel between the source electrode 8 and the drain electrode 12 in response to the scan signal supplied from the gate line 4, and thus, the source electrode 8 through the data line 2. The data signal supplied thereto is transmitted to the drain electrode 12.

Meanwhile, the pixel electrode 14 connected to the drain electrode 12 through the drain contact hole 16 is formed in a region in which the liquid crystal of the unit liquid crystal cell is located, and is made of indium tin oxide (ITO) material having high light transmittance. Is formed.

In this case, the pixel electrode 14 is connected to a liquid crystal layer together with a common electrode (not shown) formed on a color filter substrate (not shown) by a data signal supplied from the drain electrode 12. Generate an electric field.

In addition, a color filter of red (R), green (G), and blue (B) colors is formed in each unit liquid crystal cell in which the black matrix and the thin film transistor are formed.

The black matrix 72 prevents light leakage between pixels in areas corresponding to the data line 4 and the gate line 2 and the thin film transistor and prevents red (R), green (G), and blue (B) light for each pixel. It is formed to prevent interference.

When an electric field is applied to the liquid crystal layer, the liquid crystal rotates by dielectric anisotropy to transmit light emitted from a back light (not shown in the drawing) toward the color filter substrate through the pixel electrode 14, and transmits the light. The amount of light to be controlled is controlled by the voltage value of the data signal.

Meanwhile, the storage electrode 20 connected to the pixel electrode 14 through the storage contact hole 22 is deposited on the gate line 4 to form the storage capacitor 18, and the storage electrode 20 and the gate thereof. A gate insulating film (not shown), which is deposited in the process of forming the thin film transistor TFT, is inserted between the lines 4 to be spaced apart from each other.

The storage capacitor 18 as described above charges the voltage value of the scan signal during the turn-on period of the thin film transistor TFT to which the scan signal is applied to the front gate line 4, and then the thin film transistor. By supplying the charged voltage to the pixel electrode 14 during the turn-off period of the TFT, driving of the liquid crystal is maintained.

FIG. 2 shows a cross section of the TFT-LCD panel in the area A-A 'in FIG.

As shown in the drawing, the liquid crystal display device includes a TFT array substrate 50 having a thin film transistor TFT formed on each of red (R), green (G), and blue (B) unit liquid crystal cells, and the unit liquid crystal. The liquid crystal layer 80 is filled between the color filter (C / F) substrate 70 on which the color filters 73 of red (R), green (G), and blue (B) are formed corresponding to the cells.

Spacers (not shown) may be formed between the C / F substrate 70 and the TFT substrate 50 to form a space having a predetermined height. A sealant (not shown) located at the edge of the panel forms an active cell region and serves as an adhesive for fixing the C / F substrate 70 and the TFT substrate 50.

The thin film transistor TFT may include a gate electrode 10 to which a scan signal is applied, an active layer 36 provided to transmit a data signal in response to the scan signal, and an active layer 36 and a gate electrode 10 electrically connected to each other. A gate insulating film 30 which is isolated from each other, a source electrode 8 formed on the active layer 36 to apply a data signal, a drain electrode 12 applying a data signal to the pixel electrode, and a source electrode. (8) and the protective film 51 which protects the drain electrode 12. As shown in FIG. The drain electrode 12 is connected to the pixel electrode 14 through the contact hole 16, and is formed of a transparent electrode made of ITO so that the light beam is transmitted through the contact hole 16. The active layer 36 is made of amorphous silicon. A semiconductor layer 34 formed by depositing (a-Si) and an ohmic contact layer 32 doped with n + on both sides of the semiconductor layer 34 are formed.

In addition, the color filter substrate 70 may include a black matrix 72 formed corresponding to the data line 4, the gate line 2, and the thin film transistor TFT shown in FIG. The color filter 73 of the resin film which contains dyes or pigments of three basic colors red (R), green (G), and blue (B) corresponding to the green (G) and blue (B) unit liquid crystal cells, and the liquid crystal A common electrode 74 made of ITO, a transparent electrical conductor formed to apply a voltage to a cell, and an alignment film 75 formed for alignment of liquid crystal molecules.

Hereinafter, the light transmission process of the liquid crystal display device configured as described above will be described in detail.

First, the common electrode voltage is supplied to the common electrode 74 formed integrally with the front surface of the color filter substrate 70.

In the gate driver integrated circuit formed on the thin film transistor (TFT) array substrate 50, scan signals are sequentially supplied to the gate line 4. Therefore, the liquid crystal cells arranged in a matrix form are sequentially selected in units of the gate lines 4.

The scan signals supplied to the liquid crystal cells of the selected gate line 4 are applied to the gate electrode 10 of the TFTs provided in the liquid crystal cells, respectively, so as to conduct the conductive signals between the source electrode 8 and the drain electrode 12. Form a channel.

Meanwhile, data signals are supplied to the liquid crystal cells of the selected gate line 4 through the data line 2 in the data driver integrated circuit, and the data signal is supplied to the source electrode 8 of the thin film transistor TFT. Is approved.

Therefore, the data signal supplied to the source electrode 8 of the thin film transistor TFT is supplied to the drain electrode 12 through the conductive channel during the period in which the scan signal is applied, and the thin film transistor TFT of the thin film transistor TFT The data signal supplied to the drain electrode 12 is supplied to the pixel electrode 14 connected to the drain electrode 12 to drive the liquid crystal.

In addition, since the pixel electrode 14 is connected to the storage electrode 20 through the storage contact hole 22, the data signal supplied to the pixel electrode 14 is applied to the storage electrode 20 during a scan signal period. Supplied and charged to the storage capacitor 18.

The voltage charged in the storage capacitor 18 is supplied to the pixel electrode 14 during the turn-off period of the TFT (TFT) to which the scan signal is not applied, thereby maintaining the driving of the liquid crystal.

As described above, the common electrode voltage is applied to the common electrode 74 which is integrally formed on the front surface of the color filter substrate 70, and the liquid crystal selected in the unit of the gate line 4 on the TFT array substrate 50. Since the voltage of the data signal is applied to the pixel electrodes 14 of the cells, an electric field is applied to the liquid crystal layer 80 formed between the common electrode 74 and the pixel electrode 14.

When an electric field is applied to the liquid crystal layer 80, the liquid crystal is rotated by dielectric anisotropy to emit light emitted from the backlight from the TFT array substrate 50, the pixel electrode 14, the liquid crystal layer 80, and The light is transmitted through the common electrode 74 toward the color filter substrate 70.

At this time, the strength of the electric field is adjusted according to the voltage magnitude of the data signal applied to the pixel electrode 14, and the light transmittance of the liquid crystal layer 80 is controlled by the strength of the electric field.

Referring to the exemplary diagram showing the voltage waveform applied to the liquid crystal panel of FIG. 3, the common electrode voltage Vcom is applied to the common electrode 74, and the voltage value V _DATA of the data signal is applied to the data line 2. Is applied to the source electrode 8 of the thin film transistor TFT, and the scan signal V _G is applied to the gate electrode 10 of the thin film transistor TFT through the gate line 4 every frame. do.

Therefore, first, in the turn-on period of the thin film transistor TFT (TFT) to which the scan signal V _G of the nth frame is applied at high potential, the positive data signal voltage value V _DATA is the source electrode 8. Is supplied to the pixel electrode 14 through the drain electrode 12 to drive the liquid crystal, and is charged in the storage capacitor 18. At this time, the positive data signal voltage value V _DATA applied to the pixel electrode 14 is gradually charged due to the influence of the liquid crystal capacitance and the storage capacitor 18 capacitance in the turn-on period of the thin film transistor TFT. (charging), and, even when the pixel electrode voltage (V _P) waveform as shown in Fig.

Further, the scan signal (V _G) is to transition to the top low-potential thin film transistor (TFT) on the classical is turned to have a voltage drop caused by the parasitic capacitance from the charged pixel electrode voltage (V _P) when turned off, it This is called the kick-back voltage (ΔV _P ).

Further, the scan signal (V _G) a low potential to the top is a thin film transistor (TFT) uiteon is - continuously supplied to the off period of the pixel electrode voltage (V _P) charged in the storage capacitor 18. The pixel electrode 14 Thus, the driving of the liquid crystal is maintained.

On the other hand, in the n + 1 frame, since the inversion driving method described above is applied, a negative data signal voltage value V _DATA is applied from the source electrode 8 to the pixel electrode 14 through the drain electrode 12. Is supplied and charged to the storage capacitor 18.

Accordingly, the pixel electrode voltage of the n + 1 frame (V _P) of turn of a common electrode voltage thin film transistor (TFT) on the basis of (Vcom) as shown in FIG. 2 - in the off-period-on, transition, and turns the n will have a pixel electrode voltage (V _P) and a symmetrical voltage waveform of the frame.

On the other hand, when the electric field is applied to the liquid crystal layer 80 and the light emitted from the backlight is transmitted from the TFT array substrate 50 toward the color filter substrate 70, a part of the transmitted light is a color filter. Reflected by the black matrix 72 formed on the substrate 70 and the color filters 73 of red (R), green (G), and blue (B) colors, a part of the reflected light is a thin film transistor (TFT) The channel region of the thin film transistor TFT formed on the array substrate 50 is irradiated.

In this case, since the channel region of the thin film transistor TFT is a semiconductor layer 32 made of amorphous silicon, when the light is absorbed, the turn-off current of the thin film transistor TFT is increased.

As described above, when the turn-off current of the thin film transistor TFT increases, as illustrated in FIG. 3, the pixel electrode voltage V charged in the storage capacitor 18 during the turn-off period of the thin film transistor TFT. _P ) gradually decreases.

By the way, the red (R), green (G), blue (B) color filter 73 has a different reflectance of light, so the red (R), green (G), blue (B) color of the color The amount of light incident on the semiconductor layer 32 of the thin film transistor TFT formed in each liquid crystal cell corresponding to the filter 73 varies.

In particular, the red (R), blue (B) color of the red (R), green (G), blue (B) color of the red (R), blue (B) color has a low reflectance, while the green (G) color has a high reflectance Have

However, as shown in FIG. 4, the conventional liquid crystal display device has red, green, and blue colors passing through the channel layer of the thin film transistor TFT formed in each unit liquid crystal cell. Since the area of the filter 73 is the same, the amount of light reflected by the channel layer is changed, so that the electrical characteristics of the thin film transistor TFT are changed to have different turn-off currents.

That is, as shown in the graph showing the current value Ids of the drain-source according to the gate applied voltage Vg of FIG. 4, the color filter 73 in the turn-off period of the thin film transistor TFT. The turn-off current value of the waveform S1 to which the waveform is not applied is the smallest, and the waveforms S2 and S3 by the color filter 73 of red (R) and blue (B) colors are the same in size. The waveform S4 by the green (G) color filter 73 appears the largest.

As a result, as shown in a graph showing the pixel electrode voltage V _P of the liquid crystal cell according to the color filters 73 of red (R), green (G), and blue (B) colors of FIG. During the turn-off period of the TFT, the pixel electrode voltage V _P charged in the storage capacitor 18 of the liquid crystal cell corresponding to the color filter 73 of green (G) color is most severely reduced.

Accordingly, the liquid crystal display according to the related art is caused by a difference in luminance between liquid crystal cells corresponding to the color filters 73 of red (R) and blue (B) colors and liquid crystal cells corresponding to the color filter 73 of the green (G) color. There was a problem that badly flicker occurs.

Accordingly, the present invention has been made to solve the above problem, and by removing the red (R), green (G), and blue (B) color filters in the region passing through the TFT, flicker in the liquid crystal cell of a specific pixel. The purpose is to prevent deepening.

1 is an exemplary view showing a general planar configuration of a unit liquid crystal cell of a liquid crystal display.

FIG. 2 is an exemplary view illustrating a cross-sectional configuration of a thin film transistor region cut along the line AA ′ of FIG. 1.

3 is an exemplary view showing a voltage waveform applied to a liquid crystal panel in FIGS. 1 to 2.

4 to 2 are graphs showing current values Ids of the drain-source according to the gate applied voltage Vg.

5 is a graph illustrating pixel electrode voltages of liquid crystal cells according to color filters of red (R), green (G), and blue (B) colors in FIGS. 1 to 2;

6 is an exemplary view of a liquid crystal display device for a unit liquid crystal cell according to an embodiment of the present invention.

FIG. 7 is an exemplary view illustrating a cross-sectional configuration of a thin film transistor region cut along the line BB ′ of FIG.

FIG. 8 is a graph showing pixel electric voltages of red (R), green (G), and blue (B) pixel liquid crystal cells in FIGS. 6 and 7;

FIG. 9 is a graph showing the current values Ids of the drain-source according to the gate applied voltage Vg of the red (R), green (G), and blue (B) pixel liquid crystal cells in FIGS. .

*** Explanation of symbols for main parts of drawing ***

10 gate electrode 8: source electrode

12 drain electrode 14 pixel electrode

72: black matrix 73: color filter

74: common electrode

R, G, B: Red (R), Green (G), Blue (B) pixels

A liquid crystal display device of the present invention for achieving the above object is a color filter substrate having a color filter of red (R), green (G), blue (B) color; The liquid crystal cells of the red (R), green (G), and blue (B) pixels corresponding to the color filters of the red (R), green (G), and blue (B) colors are arranged in an active matrix form. A thin film transistor (TFT) array substrate having a thin film transistor (TFT) in a liquid crystal cell; In a liquid crystal display device including a liquid crystal layer filled between the color filter substrate and a thin film transistor (TFT) array substrate, a color filter is formed in a liquid crystal cell region of a pixel except for a region passing through the thin film transistor (TFT). It is characterized by that.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the liquid crystal display device of the present invention as described above.

FIG. 6 illustrates a liquid crystal display device of the present invention in which the light leakage currents of the thin film transistor TFTs for the red (R), green (G), and blue (B) pixels are the same.

As shown in the figure, the liquid crystal display device of the present invention includes a thin film transistor TFT formed at the intersection of the data line 2 and the gate line 4, and the drain electrode 12 of the thin film transistor TFT. A lower substrate including a pixel electrode 14 connected to the lower substrate; A region passing through the data line 4 and the gate line 2, a black matrix TFT formed in a region corresponding to a portion where a thin film transistor TFT is formed, and a region passing through the thin film transistor TFT The lower substrate 70 includes a color filter 73 formed in each unit pixel cell except for “a”.

The black matrix 72 is formed on the data line 4 and the gate line 2 and the thin film transistor TFT formed on the lower substrate, and is disposed between the data line 4 and the gate line 2 and the pixel electrode 51. It prevents light from leaking out and prevents light emitted from red (R), green (G), and blue (B) unit pixels from interfering with adjacent pixels.

In addition, the color filter 73 is formed only in the liquid crystal cell region except for the region where the thin film transistor TFT is formed, and the color filter 73 is formed for each red, green, and blue unit pixel. Due to the difference in the reflectance of the light, it is possible to prevent the flicker phenomenon caused by the amount of light irradiated to the channel region of the TFT.

That is, although not shown in the drawing, the light incident on the liquid crystal panel from the backlight installed under the lower substrate on which the thin film transistor (TFT) is formed is transmitted through the liquid crystal panel to display a color image on the screen. The black matrix and the color filter formed on the upper substrate reflect back to the lower substrate. The reflected light is irradiated to the channel region of the thin film transistor (TFT) to generate a light leakage current, which is caused by red (R), green (G), and blue (B) pixels due to the difference in reflectance of the color filter. Have different values for. Substantially, the reflectances of the red (R) color and the blue (B) color color filter 73 are similar to each other, but the reflectance of the green (G) color filter 73 is the red (R) color and the blue (B) color. It is much higher than the color filter 73 of () color.

Accordingly, in order to solve this problem, the present invention removes a portion of the color filter of red (R), green (G), and blue (B) colors passing through the thin film transistor (TFT).

Hereinafter, a method of manufacturing the liquid crystal display device of the present invention will be described in detail with reference to the cross section of the liquid crystal panel shown in FIG. 6.

FIG. 7 is a cross-sectional view of the liquid crystal panel taken along the line BB ′ in FIG. 6.

First, a metal, for example, Mo, Al, or Cr, is deposited on the glass substrate 1 of the TFT array substrate 50 by a sputtering method, and then patterned through a first mask to form a gate electrode. To form (10).

In addition, an insulating material such as SiNx is entirely deposited on the glass substrate 1 on which the gate electrode 10 is formed to form a gate insulating film 30.

On the gate insulating layer 30, a semiconductor layer 32 made of amorphous silicon and an ohmic contact layer 34 made of n + amorphous silicon doped with phosphorus (P) in a high concentration are successively formed. Deposition and then patterning through a second mask to form an active layer 36 of a thin film transistor (TFT) (TFT).

In addition, a metal material is deposited on the gate insulating layer 30 and the ohmic contact layer 34, and then patterned through a third mask to form the source electrode 8 and the drain electrode 12 of the TFT (TFT). To form. In this case, the source electrode 8 and the drain electrode 12 are patterned to face each other at the top of the active layer 36.

Accordingly, the ohmic contact layer 34 over the active layer 36 is exposed, and the exposed ohmic contact layer 34 is removed to expose the underlying semiconductor layer 32. 8) and the drain electrode 12 are patterned, and the exposed semiconductor layer 32 is defined as a channel region of the thin film transistor TFT.

The SiNx material may be formed through a chemical vapor deposition (CVD) method on the gate insulating layer 30 including the exposed semiconductor layer 32 and the source electrode 8, the drain electrode 12, and the like. A passivation film 38 is deposited on the entire surface. At this time, an inorganic material such as SiNx is mainly used as a material of the protective film 38, and in recent years, an organic material having a low dielectric constant such as benzocyclobutene (BCB), spin on glass (SOG) or acryl to improve the opening ratio of the liquid crystal cell Is being used.

A portion of the passivation layer 38 on the drain electrode 12 is selectively etched through a fourth mask to form a drain contact hole 16 exposing a portion of the drain electrode 12.

Then, the transparent electrode material is sputter deposited and deposited on the passivation layer 38, and then patterned through a fifth mask to form a pixel electrode 14, wherein the pixel electrode 14 is drained through the drain contact hole 16. Patterned so as to be connected to the electrode 12.

Finally, as described above, the alignment layer 51 is formed on the upper surface of the resultant in which the TFT region is formed, followed by rubbing to complete the fabrication of the TFT array substrate 50. .

Meanwhile, referring to the manufacturing process of the color filter substrate 70, first, a black matrix 72 is coated on the glass substrate 71 at regular intervals. As the material of the black matrix 72, chromium (Cr) or chromium oxide (CrOx) is used, and is formed through a sputtering method.

In addition, a color filter 73 of red (R), green (G), and blue (B) colors is formed on the glass substrate 71 in which the black matrix 72 is spaced apart from each other, respectively. ) Forms a 1: 1 correspondence with respect to one unit pixel.

Then, in order to minimize the amount of light irradiated to the thin film transistor TFT by the color filter 73, a partial region “a” of the color filter 73 passing through the thin film transistor TFT is patterned and removed. .

Substantially, lowering the reflectance of the black matrix and the color filter is an important factor for improving the quality of the liquid crystal display device. In particular, due to the difference in reflectance between color filters having red (R), green (G), and blue (B) colors, part of the light incident from the backlight is reflected on the color filter, and thus the amount of light irradiated to the TFT. Because of this difference, a luminance difference for each pixel is generated. Therefore, by removing the color filter passing over the thin film transistor TFT, the light reflected by the color filter to the thin film transistor TFT may be removed.

When the color filter is completed as described above, a metal material is formed on the upper surface of the color filter 73 and then patterned to form a common electrode 74.

Then, the alignment layer 75 is formed on the upper surface of the resultant, followed by rubbing to complete the manufacture of the upper substrate 70.

As described above, when fabrication of the thin film transistor (TFT) array substrate 50 and the color filter substrate 70 is completed, a sealing material (not shown) is printed on the thin film transistor (TFT) array substrate 50. Spacers (not shown) are scattered on the color filter substrate 70. In this case, in consideration of process requirements, the sealing material 60 may be printed on the color filter substrate 70, and the spacer may be distributed on the thin film transistor (TFT) array substrate 50.

When the sealing material 60 is printed and the dispersion of the spacer is completed, the thin film transistor (TFT) array substrate 50 and the color filter substrate 70 are bonded to each other. At this time, the alignment for bonding the TFT array substrate 50 and the color filter substrate 70 is a margin given during the design process of the TFT array substrate 50 and the color filter substrate 70. It is usually determined by the precision of about several μm, and if it is out of this, light leaks out, so that the desired image quality characteristics of the liquid crystal display cannot be expected, and the thin film transistor (TFT) array substrate 50 and the color filter can be expected. The alignment layers 51 and 75 of the substrate 70 are bonded to face each other at regular intervals, and then injected with liquid crystal and then sealed to complete the liquid crystal display device as shown in FIG.

The completed liquid crystal display device removes a portion of the red (R), green (G), and blue (B) color filters passing through the channel region of the thin film transistor (TFT), thereby reducing the thin film transistor by the reflected light of the color filter The light leakage current of the TFT can be reduced, and the luminance difference of each pixel due to the difference in reflectance of the red (R), green (G), and blue (B) color filters can be prevented. That is, as shown in the graph showing the pixel electrode voltage V _P of the red (R), green (G), and blue (B) pixel liquid crystal cells of FIG. ), The pixel electrode voltage V _P of the red (R), green (G), and blue (B) pixel liquid crystal cells is the same during the turn-off period of the thin film transistor TFT provided in the blue (B) pixel. .

In addition, in the liquid crystal display of the present invention, the red (R), green (G), and blue (B) color filters 73 passing through the channel layer of the thin film transistor (TFT) formed in each liquid crystal cell are removed. As a result, the amount of light reflected by the channel layer of the thin film transistor TFT is the same, so that the electrical characteristics of the thin film transistor TFT are equal to each other, thereby having the same turn-off current as shown in FIG. 9.

9 is a graph showing the current value Ids of the drain-source according to the gate applied voltage Vg. As shown in the drawing, the current value is shown in FIG. 4 in the turn-off period of the thin film transistor TFT. It is equal to the turn-off current value of the waveform S1 to which the filter is not applied, and has the same turn-off current value for the liquid crystal cells of the red (R), green (G), and blue (B) pixels.

The liquid crystal display according to the present invention as described above can reduce the light leakage current of the thin film transistor (TFT) by removing the color filter passing through the thin film transistor (TFT), red (R), green (G), Due to the difference in reflectance of the blue (B) color filter, the light leakage current of the TFTs provided for each liquid crystal cell is different according to the liquid crystal cells of the red (R), green (G), and blue (B) pixels. There is an effect that can prevent the flicker deepening in the liquid crystal cell of.

Claims (5)

A color filter substrate provided with color filters of red (R), green (G), and blue (B) colors; The liquid crystal cells of the red (R), green (G), and blue (B) pixels corresponding to the color filters of the red (R), green (G), and blue (B) colors are arranged in an active matrix form. A thin film transistor (TFT) array substrate having a thin film transistor (TFT) in a liquid crystal cell; In the liquid crystal display device including a liquid crystal layer filled between the color filter substrate and a thin film transistor (TFT) array substrate, the red (R), green (G), blue (B) color color filter is a thin film A liquid crystal display device characterized in that it is not formed in a portion corresponding to a region where a transistor TFT is formed. The liquid crystal display device according to claim 1, wherein the color filter is not formed at least in a portion corresponding to the channel region of the thin film transistor. The liquid crystal display device according to claim 1, wherein the light leakage current generated in the thin film transistor TFT is the same for the red, green, and blue pixels. The liquid crystal display device of claim 1, wherein the amount of light reflected by the thin film transistor (TFT) included in the red (R), green (G), and blue (B) pixels is the same. The liquid crystal display device according to claim 1, wherein the light reflected by the thin film transistor (TFT) provided in the red (R), green (G), and blue (B) pixels is caused by a black matrix.