JP2009069443A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bond a thin film transistor panel 1 and a counter panel 21 arranged opposite to each other under the thin film transistor panel 1 through a sealing material, and a liquid crystal 31 is sealed between both panels 1 and 21 inside the sealing material. In the liquid crystal display device in which the backlight 32 is disposed under the light source 21, the light use efficiency is improved.
A black mask 23 of an opposing panel 21 is formed of aluminum, silver, or an alloy thereof, and also serves as a reflective layer. When the light from the backlight 32 is applied to the lower surface of the black mask 23 that also serves as a reflective layer, the reflected light passes through the counter substrate 22, the back-side polarizing plate 27, and the light guide plate 33, and is reflected by the reflective layer 34. The light is reflected, and at least a part of the reflected light contributes to the display, so that the light use efficiency can be improved. In this case, a black mask 23 that also serves as a reflective layer may be formed on the upper surface of the counter substrate 22, so that the number of manufacturing steps does not increase and the cost does not increase.
[Selection] Figure 1

Description

  The present invention relates to a liquid crystal display device.

  In a conventional liquid crystal display device, a thin film transistor panel and a counter panel disposed on the thin film transistor panel are bonded to each other through a substantially rectangular frame-shaped sealing material, and liquid crystal is sealed between the two panels inside the sealing material. Some have a backlight disposed under the thin film transistor panel (see, for example, Patent Document 1).

JP 2006-91841 A

  In the counter panel in the conventional liquid crystal display device, a black mask is provided on the lower surface of the substrate in order to prevent light leakage from other than the substantial pixel region. On the other hand, in the thin film transistor panel, a reflective layer having the same pattern as the black mask is provided on the lower surface of the substrate. This reflective layer reflects the light from the backlight, further reflects this reflected light by the reflective layer of the backlight, and contributes to the display by at least part of the reflected light, thereby improving the light utilization efficiency. belongs to.

  However, in the above conventional liquid crystal display device, a reflective layer having the same pattern as the black mask of the counter panel must be formed on the lower surface of the thin film transistor panel substrate, which increases the number of manufacturing steps and increases the cost. There was a problem.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid crystal display device that can improve the light use efficiency and prevent the cost from increasing.

According to the first aspect of the present invention, a thin film transistor panel and a counter panel disposed opposite to each other under the thin film transistor panel are bonded to each other through a sealing material, and liquid crystal is sealed between the two panels inside the sealing material. In the liquid crystal display device in which a backlight is disposed below the counter panel, the counter panel includes a black mask that also serves as a reflective layer.
According to a second aspect of the present invention, in the first aspect of the present invention, the black mask is formed of aluminum, silver, or an alloy thereof.
The invention described in claim 3 is the pixel described in claim 2, wherein the black mask is made of a metal layer provided on the upper surface of the counter substrate of the counter panel, and is provided in the thin film transistor panel. An opening smaller than the size of the pixel electrode is provided in a portion corresponding to the electrode.
According to a fourth aspect of the present invention, in the first aspect of the invention, the backlight includes a light guide plate provided with a reflective layer on a lower surface.

  According to the present invention, since the opposing panel disposed between the thin film transistor panel and the backlight is provided with the black mask that also serves as the reflective layer, the light use efficiency can be improved, and the opposing panel A black mask that also serves as a reflective layer may be formed on the substrate, so that the number of manufacturing steps does not increase and the cost does not increase.

  FIG. 1 is a cross-sectional view of a main part of a liquid crystal display device as an embodiment of the present invention, and FIG. 2 is a transmission plan view of a part of a thin film transistor panel of the liquid crystal display device. In this case, FIG. 1 corresponds to a cross-sectional view taken along line II in FIG. In this liquid crystal display device, as shown in FIG. 1, a thin film transistor panel 1 and a counter panel 21 arranged to face each other under the thin film transistor panel 1 are bonded together via a substantially rectangular frame-shaped sealing material (not shown), The liquid crystal 31 is sealed between the panels 1 and 21 inside the sealing material, and the backlight 32 is disposed below the opposing panel 21.

  Next, the planar structure of the thin film transistor panel 1 will be described with reference to FIG. The thin film transistor panel 1 includes a thin film transistor substrate 2 made of glass or the like. A plurality of scanning lines 3 and a plurality of data lines 4 are provided in a matrix form under the thin film transistor substrate 2. In this case, the plurality of scanning lines 3 are provided extending in the row direction, and the plurality of data lines 4 are provided extending in the column direction.

  A pixel electrode 5 is provided in a region surrounded by the scanning line 3 and the data line 4 under the thin film transistor substrate 2. Here, for the purpose of clarifying FIG. 2, oblique short solid line hatching is written at the edge of the pixel electrode 5. The pixel electrode 5 is connected to the scanning line 3 and the data line 4 through a thin film transistor 6 as a switching element. A plurality of auxiliary capacitance lines 7 are provided below the thin film transistor substrate 2 so as to extend in the row direction. An auxiliary capacitance line 7 for forming an auxiliary capacitance portion with the pixel electrode 5 is overlapped with the upper side portion of the pixel electrode 5.

  Next, a description will be given with reference to FIGS. A gate electrode 8 and a scanning line 3 connected to the gate electrode 8 are provided at predetermined positions on the lower surface of the thin film transistor substrate 2. Auxiliary capacitance lines 7 are provided at other predetermined locations on the lower surface of the thin film transistor substrate 2. In this case, the gate electrode 8, the scanning line 3, and the auxiliary capacitance line 7 are formed of chromium, molybdenum, or an alloy thereof.

  A gate insulating film 9 made of silicon nitride or the like is provided on the lower surface of the thin film transistor substrate 2 including the gate electrode 8, the scanning line 3, and the auxiliary capacitance line 7. A semiconductor thin film 10 made of intrinsic amorphous silicon is provided at a predetermined position on the lower surface of the gate insulating film 9 below the gate electrode 8. A channel protective film 11 made of silicon nitride or the like is provided at substantially the center of the lower surface of the semiconductor thin film 10. Ohmic contact layers 12 and 13 made of n-type amorphous silicon are provided on both sides of the lower surface of the channel protective film 11 and on the lower surface of the semiconductor thin film 10 on both sides thereof.

  A source electrode 14 and a drain electrode 15 are provided on the lower surfaces of the ohmic contact layers 12 and 13. A data line 4 is connected to the drain electrode 15 at a predetermined position on the lower surface of the gate insulating film 9. In this case, the source electrode 14, the drain electrode 15, and the data line 4 are formed of chromium, molybdenum, or an alloy thereof. Here, the thin film transistor 6 includes a gate electrode 8, a gate insulating film 9, a semiconductor thin film 10, a channel protective film 11, ohmic contact layers 12 and 13, a source electrode 14 and a drain electrode 15.

  An overcoat film 16 made of silicon nitride or the like is provided on the lower surface of the gate insulating film 9 including the thin film transistor 6 and the data line 4. A pixel electrode 5 made of ITO or the like is provided at a predetermined position on the lower surface of the overcoat film 16. The pixel electrode 5 is connected to the source electrode 14 through a contact hole 17 provided in the overcoat film 16. An alignment film 18 is provided on the lower surface of the overcoat film 16 including the pixel electrode 5. A surface-side polarizing plate 19 is provided on the upper surface of the thin film transistor substrate 2.

  On the other hand, the counter panel 21 includes a counter substrate 22 made of glass or the like. On the upper surface of the counter substrate 22, a black mask 23, a color filter 24 made of resin or the like, a counter electrode 25 made of ITO or the like, and an alignment film 26 are provided. In this case, the black mask 23 is formed of aluminum, silver, or an alloy thereof, which is a metal material having a higher reflectance than chromium, molybdenum, or an alloy thereof, and also serves as a reflective layer. The planar shape of the black mask 23 will be described later. A back-side polarizing plate 27 is provided on the lower surface of the counter substrate 22.

  The backlight 32 has a structure in which a reflective layer 34 is provided on the lower surface of the light guide plate 33 and a light source (not shown) made of a light emitting diode or the like is provided outside one end surface of the light guide plate 33. When the light source is turned on, the light from the light source is guided by the light guide plate 33 and reflected by the reflective layer 34, and then emitted almost vertically upward from the upper surface of the light guide plate 33.

  Next, the planar shape of the black mask 23 will be described. The black mask 23 is made of a metal layer having a relatively high reflectivity provided on the upper surface of the counter substrate 22, and as shown by a one-dot chain line in FIG. 2, the black electrode 23 is formed on a portion corresponding to the pixel electrode 5. An opening 23a slightly smaller than the size is provided. The black mask 23 prevents light from the backlight 32 from entering the semiconductor thin film 10 of the thin film transistor 6, and light from the backlight 32 from a gap between the pixel electrodes 5 adjacent in the row direction and the column direction. Although it is for preventing leakage, it also serves as a reflective layer that reflects light from the backlight 32.

  In this liquid crystal display device, when the backlight 32 is turned on, the light from the backlight 32 causes the back-side polarizing plate 27, the counter substrate 22, the opening 23a of the black mask 23, the color filter 24, the counter electrode 25, the alignment. The film 26, the liquid crystal 31, the alignment film 18, the pixel electrode 5, the overcoat film 16, the gate insulating film 9, the thin film transistor substrate 2, and the surface side polarizing plate 19 are transmitted and emitted to the upper surface side of the surface side polarizing plate 19. To display.

  By the way, when the light from the backlight 32 is irradiated to the lower surface of the black mask 23 which also serves as a reflective layer in the state where such display is performed, the reflected light is reflected on the counter substrate 22, the back side polarizing plate 27 and The light is transmitted through the light guide plate 33 and is reflected by the reflective layer 34, and at least a part of the reflected light contributes to display, so that the light use efficiency can be improved.

  As described above, in this liquid crystal display device, since the counter panel 21 disposed between the thin film transistor panel 1 and the backlight 32 is provided with the black mask 23 that also serves as a reflective layer, the light use efficiency is improved. Can do. In addition, a black mask 23 that also serves as a reflective layer may be formed on the upper surface of the counter substrate 22, so that the number of manufacturing steps does not increase and the cost does not increase.

Sectional drawing of the principal part of the liquid crystal display device as one Embodiment of this invention. FIG. 2 is a partially transparent plan view of a thin film transistor panel of the liquid crystal display device shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin-film transistor panel 2 Thin-film transistor substrate 3 Scan line 4 Data line 5 Pixel electrode 6 Thin-film transistor 7 Auxiliary capacity line 16 Overcoat film 18 Orientation film 19 Surface side polarizing plate 21 Opposite panel 22 Opposite substrate 23 Black mask 24 Color filter 25 Common electrode 26 Orientation Film 31 Liquid crystal 32 Backlight 33 Light guide plate 34 Reflective layer

Claims (4)

  A thin film transistor panel and a counter panel disposed under the thin film transistor panel are bonded to each other through a sealing material, liquid crystal is sealed between the two panels inside the sealing material, and a backlight is disposed under the counter panel. In the liquid crystal display device, the counter panel includes a black mask that also serves as a reflective layer.   2. The liquid crystal display device according to claim 1, wherein the black mask is made of aluminum, silver or an alloy thereof.   3. The invention according to claim 2, wherein the black mask is made of a metal layer provided on the upper surface of the counter substrate of the counter panel, and the pixel electrode is provided in a portion corresponding to the pixel electrode provided in the thin film transistor panel. A liquid crystal display device having an opening smaller than the size of the liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the backlight includes a light guide plate provided with a reflective layer on a lower surface thereof.

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