KR20170101777A - Liquid Crystal Display Device - Google Patents

Abstract

The present invention provides a liquid crystal display device which can obtain high transmissivity and simultaneously improves display quality by reducing moire. The liquid crystal display device of the present invention comprises: a backlight; a first liquid crystal panel located at an upper part of the backlight; and a second liquid crystal panel located between the backlight and the first liquid crystal panel. Each of the first and second liquid crystal panels has a display surface side upper part glass substrate and a backlight side lower glass substrate. In the first liquid crystal panel, the upper glass substrate has a color filter and a black matrix. In the second liquid crystal panel, the upper glass substrate forms the black matrix only a region corresponding to a thin film transistor channel formed in the lower glass substrate.

Description

[0001] The present invention relates to a liquid crystal display device,

The present invention relates to a liquid crystal display device constituted by superimposing a plurality of liquid crystal panels.

Conventionally, a red-green-blue (RGB) panel, a backlight-side LV (light valve) panel, and two liquid crystal panels are overlapped with each other and a polarizing plate through each liquid crystal panel is arranged to be orthogonal to each other, There is known a liquid crystal display device which realizes a high contrast by using the contrast of the entire device as a product of the contrast of each liquid crystal panel (see, for example, Patent Document 1).

In such a liquid crystal display device, a liquid crystal panel having a wide viewing angle is used as both an LV panel and an RGB panel in order to secure a wide viewing angle characteristic from the point that the light transmitted through the LV panel passes through the RGB panel again. Examples of the liquid crystal panel having a wide viewing angle include liquid crystal panels of IPS (In Plane Switching) mode and VA (Vertical Alignment) mode, and other birefringent mode liquid crystal panels.

The configuration of the conventional RGB panel and LV panel will be described with reference to FIGS. 8 to 9. FIG. Here, the case where both the RGB panel and the LV panel are IPS mode liquid crystal panels will be described as an example. 8 is a plan view showing unit pixels of a conventional RGB panel. 9 is a plan view showing a unit pixel of a conventional LV panel.

8, subpixels corresponding to RGB (red, green, blue) of the color filter are provided in the unit pixels of the RGB panel, and each of the subpixels is divided by the black matrix provided in the RGB panel. In Fig. 9, the unit pixels of the LV panel include subpixels divided by a black matrix like the RGB panel.

Patent Document 1: JP-A-5-88197

However, in a liquid crystal display device in which two liquid crystal panels are overlapped, there is a problem that the contrast is improved but the transmittance is lower than that of the liquid crystal display device of one liquid crystal panel. This is due to the fact that the light is blocked by the black matrix provided on the LV panel, and the light is blocked by the black matrix installed on the RGB panel and the black matrix on the LV panel.

Further, in a liquid crystal display device in which two liquid crystal panels are superimposed, a moire caused by structural interference between microstructures having equivalent periods of adjacent liquid crystal panels (for example, a gate line, a data line, or a black matrix) There is a problem that the display quality is deteriorated. Here, the thickest among the gate line, the data line and the black matrix is a black matrix, and the thicker the black matrix, the stronger the moiré.

That is, in the conventional liquid crystal display device in which two liquid crystal panels are stacked, the RGB panel and the LV panel are manufactured by the same design rule for the purpose of preventing image quality deterioration. Therefore, it is necessary to secure the machine in duplicate.

An object of the present invention is to provide a liquid crystal display device capable of securing a high transmittance and reducing moire to improve display quality.

A liquid crystal display device according to the present invention includes a backlight, a first liquid crystal panel positioned above the backlight, and a second liquid crystal panel positioned between the backlight and the first liquid crystal panel, Each of the two liquid crystal panels includes a display surface side upper glass substrate and a backlight side lower glass substrate, wherein the upper glass substrate in the first liquid crystal panel has a color filter and a black matrix, In the glass substrate, a black matrix is formed only in a region corresponding to the channel of the thin film transistor formed on the lower glass substrate.

According to the liquid crystal display device of the present invention, each of the plurality of liquid crystal panels includes a display surface side upper glass substrate and a backlight side lower glass substrate, the uppermost glass substrate in the liquid crystal panel closest to the display surface includes a color filter, In the liquid crystal panel except for the liquid crystal panel on the most display surface side among the plurality of liquid crystal panels, a black matrix is formed only in the region corresponding to the channel of the thin film transistor formed on the lower glass substrate.

Thereby, it is possible to obtain a liquid crystal display device capable of securing a high transmittance and reducing moire to improve display quality.

1 is a cross-sectional view showing a liquid crystal display device according to Embodiment 1 of the present invention.
2 is a plan view showing unit pixels of a backlight side LV panel of a liquid crystal display device according to Embodiment 1 of the present invention.
3 (a) and 3 (b) are cross-sectional views schematically showing a display panel side RGB panel of a liquid crystal display device according to Embodiment 1 of the present invention.
4 is a cross-sectional view schematically showing a backlight side LV panel of a liquid crystal display device according to Embodiment 1 of the present invention.
5 is a cross-sectional view schematically showing a backlight side lower glass substrate of a backlight side LV panel of a liquid crystal display device according to Embodiment 1 of the present invention, as compared with the conventional one.
6 (a) and 6 (b) are explanatory diagrams showing effects of the liquid crystal display device according to the first embodiment of the present invention.
Fig. 7 is an explanatory view showing effects of the liquid crystal display device according to the first embodiment of the present invention. Fig.
8 is a plan view showing unit pixels of a conventional RGB panel.
9 is a plan view showing a unit pixel of a conventional LV panel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the liquid crystal display device according to the present invention will be described with reference to the drawings, and the same or corresponding parts in the drawings are denoted by the same reference numerals.

In the following embodiments, a liquid crystal display device in which two liquid crystal panels are superimposed is described as an example, but the present invention is not limited thereto, and the same description is applied to a liquid crystal display device in which three or more liquid crystal panels are superimposed.

≪ Embodiment 1 >

1 is a cross-sectional view showing a liquid crystal display device according to Embodiment 1 of the present invention. 1, the liquid crystal display device 100 is composed of a backlight 10, a display side RGB panel 20, a backlight side LV panel 30, and a light diffusion layer 40. The RGB panel 20 and the LV panel 30 are IPS mode liquid crystal panels having wide viewing angle characteristics. The display side RGB panel 20 may be referred to as a first liquid crystal panel and the backlight side LV panel 30 may be referred to as a second liquid crystal panel. In this case, the first liquid crystal panel 20 is positioned above the backlight 10 and the second liquid crystal panel 30 is positioned between the backlight 10 and the first liquid crystal panel 20. At least one liquid crystal panel may be disposed between the first liquid crystal panel 20 and the second liquid crystal panel 30.

The backlight 10 is mounted, for example, on the bottom of a case (not shown) having a light shielding property such as plastic, and irradiates light toward the LV panel 30. [ The backlight 10 includes a light emitting diode (LED), a light guide plate, and an optical sheet, but is not shown.

The RGB panel 20 includes a display surface side upper glass substrate 21, a backlight side lower glass substrate 22, a liquid crystal layer (not shown) in which liquid crystal is sealed between the upper glass substrate 21 and the lower glass substrate 22 A first polarizing plate 23 attached to the display surface side of the upper glass substrate 21 and a second polarizing plate 24 attached to the backlight side of the lower glass substrate 22. [

Here, the first polarizing plate 23 and the second polarizing plate 24 respectively transmit only light in a specific vibration direction, and the first polarizing plate 23 and the second polarizing plate 24 are arranged orthogonally to each other in the polarizing direction . Between the upper glass substrate 21 and the lower glass substrate 22, a common electrode for driving liquid crystal, a color filter for adding RGB color to light passing through, and an alignment film are provided, but these are omitted.

The LV panel 30 includes a display surface side upper glass substrate 31, a backlight side lower glass substrate 32, a liquid crystal layer (not shown) in which liquid crystal is sealed between the upper glass substrate 31 and the lower glass substrate 32 A first polarizing plate 33 attached to the display surface side of the upper glass substrate 31 and a second polarizing plate 34 attached to the backlight side of the lower glass substrate 32.

Here, the first polarizing plate 33 and the second polarizing plate 34 transmit only light in a specific vibration direction, and the first polarizing plate 33 and the second polarizing plate 34 are arranged orthogonally to each other in the polarizing direction . A common electrode for liquid crystal driving, an alignment film, and the like are provided between the upper glass substrate 31 and the lower glass substrate 32, but the illustration is omitted.

Further, since the LV panel 30 only controls the amount of light passing therethrough, a color filter is unnecessary. Further, from the viewpoint that a color filter is unnecessary, it is also possible to perform control in units of one pixel by combining three subpixels in the LV panel as shown in Fig.

In the RGB panel 20 and the LV panel 30, the polarizing directions of the second polarizing plate 24 of the RGB panel 20 and the first polarizing plate 33 of the LV panel 30 coincide with each other. Even if the first polarizing plate 33 and the light-diffusing layer 40 are omitted from the point where the polarizing direction of the second polarizing plate 24 of the RGB panel 20 coincides with the polarizing direction of the first polarizing plate 33 of the LV panel 30 do.

The light diffusion layer 40 diffuses incident light and emits the light. The light-diffusing layer 40 may be a sheet or a resin or an adhesive as long as the light diffuses and emits incident light. In Embodiment 1 of the present invention, for example, a TAC (triacetylcellulose) diffusion sheet is used as the light diffusion layer 40.

3 (a) and 3 (b) are sectional views schematically showing a display panel side RGB panel of a liquid crystal display device according to Embodiment 1 of the present invention. 3 (a), a color filter 25 and a black matrix 26 are formed on the upper glass substrate 21 of the RGB panel 20 and are sealed with an overcoat layer 27. For example, the color filter 25 may include red, green, and blue sub-color filters that add red, green, and blue to the passing light, and light is blocked by the black matrix 26. 3 (b) shows that the black matrix 26 is removed from FIG. 3 (a).

3 (a) and 3 (b), when green light is emitted from the RGB panel 20, for example, green subpixels are driven. At this time, when the black matrix 26 is not formed by diffusing the light transmitted through the lower glass substrate 22, the diffused light passes through the red or blue color filter, resulting in color mixing. That is, the black matrix 26 is required for the upper glass substrate 21 of the RGB panel 20 to prevent color mixture and emit light of a single color.

On the other hand, since the LV panel 30 only controls the amount of light passing therethrough and the image displayed on the liquid crystal display device 100 depends on the RGB panel 20, strict design rules are not required Do not. In other words, since the LV panel 30 only emits white light, a color filter is unnecessary, and color mixing does not occur, so that it is not necessary to form a black matrix.

4 is a cross-sectional view schematically showing a backlight side LV panel of a liquid crystal display device according to Embodiment 1 of the present invention. 4, a black matrix is not formed on the upper glass substrate 31 of the LV panel 30 in a region corresponding to the black matrix 26 of the RGB panel 20, and a black matrix is formed on the lower glass substrate 32 A black matrix is formed only in a region corresponding to a channel of a thin film transistor (not shown).

The reason why the black matrix is formed only in the region corresponding to the channel of the thin film transistor is to prevent the thin film transistor from being abnormally driven by light from the outside. Further, the LV panel 30 may be controlled on a subpixel-by-subpixel basis, or may be controlled in units of one pixel by combining three subpixels. The overcoat layer 35 may also be removed from the point where the color filter is unnecessary.

Thus, by removing the black matrix from the upper glass substrate 31 of the LV panel 30 except for the region corresponding to the channel of the thin film transistor, the light is blocked by the black matrix provided on the LV panel , The light is not blocked due to a deviation between the black matrix provided on the RGB panel and the black matrix provided on the LV panel, and the transmittance can be improved. Also, moire can be reduced by removing the black matrix.

5 is a cross-sectional view schematically showing a backlight side lower glass substrate of a backlight side LV panel of a liquid crystal display device according to Embodiment 1 of the present invention, as compared with the conventional one. 5 shows the lower glass substrate of the conventional LV panel at the upper end and the lower glass substrate 32 of the LV panel 30 according to the first embodiment of the present invention at the lower end.

5, the common electrode 36, the pixel electrode 37, and the data line 38 are formed on the lower glass substrate 32 of the LV panel 30. [ And a gate line (not shown) is formed so as to intersect the data line 38 at right angles. Here, the lower glass substrate 32 has a Vcom top structure in which the common electrode 36 is formed on the data line 38. According to the Vcom top structure, even if an electric field is generated, no behavior occurs in the liquid crystal of the data line shape, and light leakage can be prevented.

At this time, in the upper glass substrate 31 of the LV panel 30, by removing the black matrix except for the region corresponding to the channel of the thin film transistor, the opening area of the lower glass substrate 32 can be enlarged to enlarge the pixel region have. As a result, the aperture ratio of the LV panel 30 can be improved and the transmittance can be improved.

The pixel electrode of the RGB panel 20 has a smaller area than that of the pixel electrode 37 of the LV panel 30. [ The distance between the adjacent data lines and the pixel electrodes in the RGB panel 20 is larger than the distance between the adjacent data lines 38 and the pixel electrodes 37 in the LV panel 30. [

That is, the critical dimension (CD) of the boundary line constituting the boundary for each pixel can be reduced from the line width of the black matrix to the line width of the data line 38 or the gate line.

More specifically, the CD on the side of the data line 38 is reduced from 7 to 8 mu m of the black matrix to 3 to 4 mu m of the data line 38, and the CD on the gate line side is reduced from 15 to 20 mu m of the black matrix The gate line can be reduced to 8 to 10 mu m. When the data line 38 is opened, since light leaks, it is necessary to secure a process margin of about 1 to 3 mu m on one side.

Even if an electric field is coupled between the common electrode 36 and the pixel electrode 37 of the adjacent pixel or between the common electrode 36 and the data line 38 and the light leaks, 20), the influence is hardly generated. Specifically, in the case of a liquid crystal panel having a contrast of 1000: 1, even if light of 10 nits is emitted from the LV panel, it is reduced to about 0.01 nit when passing through the RGB panel.

In this manner, in the lower glass substrate 32 of the LV panel 30, the aperture ratio of the LV panel 30 can be increased by enlarging the aperture and enlarging the pixel area, thereby improving the transmittance. Moiré can also be reduced by reducing the CD of the boundary line constituting the boundary of each pixel from the line width of the black matrix to the line width of the data line 38 or the gate line.

Hereinafter, effects of the liquid crystal display device 100 having the above-described configuration will be described with reference to Figs. FIGS. 6A and 6B are explanatory diagrams showing effects of the liquid crystal display device according to the first embodiment of the present invention. FIGS. 6A and 6B are diagrams showing a conventional liquid crystal display device, 4 is a graph and a table showing a relationship between a driving voltage and a transmittance for a liquid crystal display device (see Figs. 4 and 5) in which a black matrix is removed and a pixel is enlarged.

6 (a) and 6 (b), the maximum transmittance value of the conventional liquid crystal display device is 0.17881 (8 V), whereas the maximum transmittance value of the liquid crystal display device in which the black matrix is removed and the pixels are enlarged is 0.19927 , And the transmittance is improved by 10% or more.

Fig. 7 is an explanatory view showing effects of the liquid crystal display device according to the first embodiment of the present invention. Fig. Fig. 7 is a graph showing the relationship between the voltage applied to the liquid crystal display device (refer to Figs. 4 and 5) and the liquid crystal display device (see Fig. 4) And 9 V are applied to the unit pixel.

In Fig. 7, it can be seen that, in the liquid crystal display device in which the black matrix is removed as compared with the conventional liquid crystal display device, and in the liquid crystal display device in which the pixels are enlarged by removing the black matrix, no light spots are generated even though there is no black matrix. Also, it can be seen that the CD of the boundary line constituting the boundary of each pixel is reduced from the line width of the black matrix to the line width of the data line or the gate line, and the opening is enlarged.

As described above, according to the first embodiment, in the liquid crystal display device constructed by superimposing a plurality of liquid crystal panels, each of the plurality of liquid crystal panels has the display surface side upper glass substrate and the backlight side lower glass substrate, The upper glass substrate in the liquid crystal panel has a color filter that adds red, green, and blue to light passing therethrough, and a black matrix that blocks light. The liquid crystal panel includes a plurality of liquid crystal panels, In the glass substrate, a black matrix is formed only in a region corresponding to the channel of the thin film transistor formed on the lower glass substrate.

In the liquid crystal panel excluding the liquid crystal panel on the most display surface side among the plurality of liquid crystal panels, the pixel region of the lower glass substrate is extended to the data line and the gate line.

Thereby, it is possible to obtain a liquid crystal display device capable of securing a high transmittance and reducing moire to improve display quality.

In the first embodiment, the case where the color filter 25 is formed on the upper glass substrate 21 of the RGB panel 20 has been described as an example. However, the present invention is not limited to this, A color filter may be formed on the substrate 22.

In the first embodiment, an IPS mode liquid crystal panel is used as the RGB panel 20 and the LV panel 30, but other liquid crystal panels having wide viewing angle characteristics may be used.

In addition, in Embodiment 1, it is possible to realize the liquid crystal panel other than the IPS mode liquid crystal panel, for example, the VA mode liquid crystal panel and the TN mode liquid crystal panel, by removing the black matrix of the LV panel and reducing the blocking of light. However, in enlarging the pixel region of the lower glass substrate in the VA mode and the TN mode liquid crystal panel, it is necessary to consider the influence of the light source by the electric field coupling.

10: Backlight 20: RGB panel
21: upper glass substrate 22: lower glass substrate
23: first polarizing plate 24: second polarizing plate
25: Color filter 26: Black matrix
27: overcoat layer 30: LV panel
31: upper glass substrate 32: lower glass substrate
33: first polarizing plate 34: second polarizing plate
35: overcoat layer 36: common electrode
37: pixel electrode 38: data line
40: light diffusion layer 100: liquid crystal display

Claims (10)

Backlight;
A first liquid crystal panel located at an upper portion of the backlight;
And a second liquid crystal panel positioned between the backlight and the first liquid crystal panel,
Wherein each of the first and second liquid crystal panels includes a display surface side upper glass substrate and a backlight side lower glass substrate,
Wherein the upper glass substrate in the first liquid crystal panel has a color filter and a black matrix,
Wherein the upper glass substrate of the second liquid crystal panel has a black matrix formed only in a region corresponding to a channel of the thin film transistor formed on the lower glass substrate.
The method according to claim 1,
And the second liquid crystal panel does not have a color filter.
3. The method according to claim 1 or 2,
Wherein the second liquid crystal panel is an IPS mode liquid crystal panel having a Vcom top structure in which a common electrode is formed on a data line.
The method of claim 3,
Wherein the pixel region of the lower glass substrate is extended to the data line and the gate line in the second liquid crystal panel.
3. The method according to claim 1 or 2,
And a light diffusion layer provided between the first and second liquid crystal panels for diffusing and emitting incident light.
3. The method according to claim 1 or 2,
Wherein the second liquid crystal panel has no overcoat layer.
3. The method according to claim 1 or 2,
Wherein the first liquid crystal panel has a wide viewing angle characteristic.
3. The method according to claim 1 or 2,
Wherein the first liquid crystal panel is a RGB panel and the second liquid crystal panel is a light valve (LV) panel.
3. The method according to claim 1 or 2,
Wherein the first liquid crystal panel includes a first pixel electrode in the form of a plate, the second liquid crystal panel includes a second pixel electrode in a plate shape,
Wherein an area of the second pixel electrode is larger than an area of the first pixel electrode.
3. The method according to claim 1 or 2,
Wherein the first liquid crystal panel includes a first pixel electrode and a first data line, the second liquid crystal panel includes a second pixel electrode and a second data line,
Wherein a first distance between the first pixel electrode and the first data line is greater than a second distance between the second pixel electrode and the second data line.

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