JP5066943B2 - Liquid crystal display - Google Patents

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 2005-345581 A

  The thin film transistor panel in the conventional liquid crystal display device includes a thin film transistor substrate, a thin film transistor having a gate electrode, a source electrode, and a drain electrode provided on the thin film transistor substrate, and a scanning line provided on the thin film transistor substrate and connected to the gate electrode. And a data line provided on the thin film transistor substrate and connected to the drain electrode, and a pixel electrode provided on the thin film transistor substrate and connected to the source electrode.

  In this case, the gate electrode and the scanning line are formed of tantalum. The source electrode, the drain electrode and the data line are made of ITO. The pixel electrode includes a transmissive pixel electrode portion made of ITO and a reflective pixel electrode portion made of a silver alloy. On the other hand, a black matrix is provided in a portion corresponding to the scan line and the data line under the counter substrate of the counter panel.

  By the way, in the conventional liquid crystal display device, when it is used as a transmissive type, light from the backlight is transmitted through the transmissive pixel electrode portion and the like and emitted to the upper surface side of the counter panel to perform display. At this time, the light from the backlight is reflected by the reflection pixel electrode part, and this reflected light is further reflected by the backlight. When this reflected light passes through the transmission pixel electrode part, this transmitted light contributes to display. It will be.

However, the conventional liquid crystal display device is formed, since the scanning lines are formed by the low reflectance tantalum, not light from the backlight is mostly reflected by the scan line and the data line is a transparent ITO Since the black matrix is provided in the part corresponding to the data line under the counter substrate, even if the light from the backlight passes through the data line, it is hardly reflected by the black matrix, and the light use efficiency is poor. was there.

  Accordingly, an object of the present invention is to provide a liquid crystal display device capable of improving the light utilization efficiency.

In order to achieve the above-described object, according to one aspect of the liquid crystal display device of the present invention, a thin film transistor panel and a counter panel disposed opposite to each other on the thin film transistor panel are bonded to each other through a sealing material, and the inside of the sealing material is In a liquid crystal display device in which liquid crystal is sealed between both panels and a backlight is disposed under the thin film transistor panel, the thin film transistor panel includes a thin film transistor substrate, a first reflective film formed on an upper surface of the thin film transistor substrate, a first reflecting film insulating film provided to cover the thin film transistor substrate comprising, provided on the insulating film, and a thin film transistor having a gate electrode, a source electrode and a drain electrode provided on the insulating film, the gate and scan lines connected to the electrode provided on the insulating film A data line connected to the drain electrode, provided on the insulating film, and a pixel electrode connected to the source electrode, the first reflective film, under at least the scanning lines and the data lines under And provided separately from each other .

  According to the present invention, the gate electrode serving as the reflective film is provided on the upper surface of the thin film transistor substrate by providing the reflective film on the thin film transistor substrate at least under the scanning line and the data line, or when the thin film transistor is an inverted stagger type. By providing a scanning line and providing a reflective film on the upper surface of the thin film transistor substrate at least under the data line, or when the thin film transistor is a staggered type, a source electrode, a drain electrode, and a reflective film on the upper surface of the thin film transistor substrate, and By providing the data line and providing the reflective film on the upper surface of the thin film transistor substrate at least below the scanning line, the light use efficiency can be improved.

(First embodiment)
FIG. 1 shows a cross-sectional view of a main part of a liquid crystal display device as a first embodiment of the present invention, and FIG. 2 shows 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, a thin film transistor panel 1 and a counter panel 31 arranged opposite to each other on the thin film transistor panel 1 are bonded to each other via a substantially rectangular frame-shaped sealing material (not shown), and both panels inside the sealing material. A liquid crystal 41 is sealed between 1 and 31 and a backlight 42 is disposed under the thin film transistor panel 1.

  First, 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 on 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 rectangular pixel electrode 5 is provided in a region surrounded by the scanning line 3 and the data line 4 on the thin film transistor substrate 2. Here, for the purpose of clarifying FIG. 2, oblique short solid hatching is written at the edge of the pixel electrode 5 (the same applies hereinafter). 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.

  On the thin film transistor substrate 2, a plurality of auxiliary capacitance lines 7 are provided extending 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. In this case, the width of the portion of the auxiliary capacitance line 7 that intersects the data line 4 is narrower than the width of the other portions (see FIG. 5).

  Next, a description will be given with reference to FIGS. First to fourth reflective films 8a, 8b, 8c, and 8d made of a highly reflective metal such as silver or a silver alloy are provided at predetermined locations on the upper surface of the thin film transistor substrate 2. The first to fourth reflective films 8a, 8b, 8c, and 8d will be described later. A lower insulating film 9 made of silicon nitride or the like is provided on the upper surface of the thin film transistor substrate 2 including the first to fourth reflective films 8a, 8b, 8c, and 8d.

  A gate electrode 10 (see FIG. 5) made of chromium or the like and a scanning line 3 connected to the gate electrode 10 are provided at predetermined locations on the upper surface of the lower insulating film 9. Auxiliary capacitance lines 7 made of chromium or the like are provided at other predetermined locations on the upper surface of the lower insulating film 9. A gate insulating film 11 made of silicon nitride or the like is provided on the upper surface of the thin film transistor substrate 2 including the gate electrode 10, the scanning line 3, and the auxiliary capacitance line 7.

  A semiconductor thin film 12 made of intrinsic amorphous silicon is provided at a predetermined position on the upper surface of the gate insulating film 11 on the gate electrode 10. A channel protective film 13 made of silicon nitride or the like is provided at substantially the center of the upper surface of the semiconductor thin film 12. Ohmic contact layers 14 and 15 made of n-type amorphous silicon are provided on both sides of the upper surface of the channel protective film 13 and on the upper surface of the semiconductor thin film 12 on both sides thereof.

  A source electrode 16 and a drain electrode 17 made of chromium or the like are provided on the upper surfaces of the ohmic contact layers 14 and 15. A data line 4 made of chromium or the like is connected to the drain electrode 17 at a predetermined location on the upper surface of the gate insulating film 11. Here, the thin film transistor 6 is an inverted stagger type, and includes a gate electrode 10, a gate insulating film 11, a semiconductor thin film 12, a channel protective film 13, ohmic contact layers 14 and 15, a source electrode 16 and a drain electrode 17. .

  An overcoat film 18 made of silicon nitride or the like is provided on the upper surface of the gate insulating film 11 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 location on the upper surface of the overcoat film 18. The pixel electrode 5 is connected to the source electrode 16 through a contact hole 19 provided in the overcoat film 18. An alignment film 20 is provided on the upper surface of the overcoat film 18 including the pixel electrode 5. A polarizing plate 21 is provided on the lower surface of the thin film transistor substrate 2.

  On the other hand, the counter panel 31 includes a counter substrate 32 made of glass or the like. On the lower surface of the counter substrate 32, a black matrix 33, a color filter 34, a counter electrode 35 made of ITO or the like, and an alignment film 36 are provided. The black matrix 33 will be described later. A polarizing plate 37 is provided on the upper surface of the counter substrate 32.

  The backlight 42 has a structure in which a reflective layer 44 is provided on the lower surface of the light guide plate 43 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 43. When the light source is turned on, light from the light source is guided by the light guide plate 43 and reflected by the reflective layer 44, and then emitted from the upper surface of the light guide plate 43 substantially vertically upward.

  Here, FIG. 3 is a plan view for explaining the first to fourth reflective films 8a, 8b, 8c, 8d and the like shown in FIGS. The first and second reflective films 8a and 8b are provided so as to extend in the row direction continuously. The third reflective film 8c is provided to extend in the column direction between the first and second reflective films 8a and 8b adjacent to each other. The fourth reflective film 8d is provided so as to protrude upward from a predetermined location on the upper side of the first reflective film 8a. In this case, the first to fourth reflective films 8a, 8b, 8c, and 8d are formed so as to be continuous with each other.

  The first and second reflective films 8a and 8b are overlapped with the scanning line 3 including the gate electrode 10 shown in FIG. 2, the auxiliary capacitance line 7, and all the gaps therebetween. The third reflection film 8c is overlapped with all the data lines 4 shown in FIG. 2 between the first and second reflection films 8a and 8b adjacent to each other. The fourth reflective film 8d is overlaid on all the portions of the source electrode 16 shown in FIG. 2 that protrude above the gate electrode 10.

  Next, the black matrix 33 will be described with reference to FIG. In FIG. 3, what is indicated by a two-dot chain line that is slightly smaller than the pixel electrode 5 indicates an opening 33 a of the black matrix 33. A light-shielding metal material is arranged in the outer region of the opening 33a of the black matrix 33, and the inner region is an opened region. In this case, the black matrix 33 is for preventing light from the backlight 42 from leaking from the gaps between the first to fourth reflective films 8a, 8b, 8c, 8d and the pixel electrode 5. is there.

  In this liquid crystal display device, when the backlight 42 is turned on, the light from the backlight 42 is polarized, the thin film transistor substrate 2, the lower layer insulating film 9, the gate insulating film 11, the overcoat film 18, the pixel electrode 5, The alignment film 20, the liquid crystal 41, the alignment film 36, the counter electrode 35, the color filter 34, the counter substrate 32, and the polarizing plate 37 are transmitted to the upper surface side of the polarizing plate 37, thereby performing display.

  By the way, when light from the backlight 42 is irradiated on the lower surfaces of the first to fourth reflective films 8a, 8b, 8c, and 8d in such a display state, the reflected light is transmitted to the thin film transistor substrate 2. Then, the light passes through the polarizing plate 21 and the light guide plate 43 and is reflected by the reflective layer 44, and at least a part of the reflected light contributes to the display, so that the light use efficiency can be improved. The first to fourth reflective films 8a, 8b, 8c, and 8d may be electrically connected to nowhere, and are the same as any one of the scanning line 3, the data line 4, and the auxiliary capacitance line 7. An electric potential or a different electric potential may be applied.

(Second Embodiment)
FIG. 4 shows a cross-sectional view of a main part of a liquid crystal display device as a second embodiment of the present invention, and FIG. 5 shows a transmission plan view of a part of a thin film transistor panel of the liquid crystal display device. In this case, FIG. 4 corresponds to a cross-sectional view taken along line IV-IV in FIG. FIG. 6 is a plan view for explaining the reflective film shown in FIGS.

  This liquid crystal display device is different from the liquid crystal display device shown in FIGS. 1 to 3 in that the first to fourth reflective films 8a, 8b, 8c, and 8d are separated from each other. In this case, the first reflective film 8 a is overlapped with all the scanning lines 3 including the gate electrode 10. The second reflective film 8 b is overlapped with all the auxiliary capacitance lines 7.

  In this case, the scanning line 3, the auxiliary capacitance line 7, the data line 4, and the source electrode 16 have parasitic capacitances through the first to fourth reflective films 8a, 8b, 8c, and 8d. Can be prevented. Note that the first and second reflective films 8a and 8b may not be electrically connected anywhere and may be provided with an appropriate potential.

(Third embodiment)
FIG. 7 shows a cross-sectional view of a main part of a liquid crystal display device as a third embodiment of the present invention. In this liquid crystal display device, the difference from the liquid crystal display device shown in FIG. 4 is that the lower insulating film 9 is omitted, and the first to fourth reflective films 8a, 8b, 8c, and 8d are provided on the upper surface of the thin film transistor substrate 2, The scanning line 3 including the gate electrode 10 is provided on the upper surface of the first reflective film 8a, and the auxiliary capacitance line 7 is provided on the upper surface of the second reflective film 8b.

  In this case, since the lower insulating film 9 is not provided, a process for forming the lower insulating film 9 is not required, and the number of processes can be reduced accordingly. Further, since the scanning line 3 and the auxiliary capacitance line 7 including the gate electrode 10 substantially have a two-layer structure having the first and second reflecting films 8a and 8b, the wiring resistance is lowered, and sometimes The constant can be reduced. The third reflective film 8c may not be electrically connected anywhere, and may be provided with an appropriate potential.

(Fourth embodiment)
FIG. 8 shows a cross-sectional view of a main part of a liquid crystal display device as a fourth embodiment of the present invention. This liquid crystal display device is different from the liquid crystal display device shown in FIG. 7 in that the first and second reflective films 8a and 8b are omitted, and the scanning line 3 including the gate electrode 10 and the auxiliary capacitance line 7 are replaced with The fourth reflective films 8c and 8d are formed of a highly reflective metal such as silver or a silver alloy, and the scanning line 3 including the gate electrode 10 and the auxiliary capacitance line 7 also serve as the reflective film.

  In this case, the scanning line 3 including the gate electrode 10, the auxiliary capacitance line 7, and the third and fourth reflection films 8c and 8d can be formed in the same process. Compared with, the number of steps can be reduced accordingly. The third reflective film 8c may not be electrically connected anywhere, and may be provided with an appropriate potential.

(Fifth embodiment)
FIG. 9 shows a cross-sectional view of a main part of a liquid crystal display device as a fifth embodiment of the present invention. This liquid crystal display device is greatly different from the liquid crystal display device shown in FIG. 1 in that the thin film transistor 6 is a staggered type.

  That is, the thin film transistor 6 includes a source electrode 16 and a drain electrode 17 made of chromium or the like provided on the upper surface of the lower insulating film 9 and an ohmic contact made of n-type amorphous silicon provided on the upper surfaces of the source electrode 16 and the drain electrode 17. The semiconductor thin film 12 made of amorphous silicon provided on the upper surfaces of the layers 14 and 15, the upper surfaces of the ohmic contact layers 14 and 15 and the lower insulating film 9 therebetween, and the upper surface of the gate insulating film 11 on the semiconductor thin film 12. And a gate electrode 10 made of chromium or the like.

  In this case, the scanning line 3 and the auxiliary capacitance line 7 connected to the gate electrode 10 are provided on the upper surface of the gate insulating film 11 by being formed of chromium or the like. The data line 4 connected to the drain electrode 17 is provided by being formed of chromium or the like on the upper surface of the lower insulating film 9. The pixel electrode 5 is connected to the source electrode 16 through a contact hole 19 provided in the gate insulating film 11 and the overcoat film 18.

  In the liquid crystal display device having such a staggered thin film transistor 6, the first to fourth reflective films 8a, 8b, 8c, and 8d are mutually connected as in the sixth embodiment of the present invention shown in FIG. You may make it isolate | separate.

  Further, as in the seventh embodiment of the present invention shown in FIG. 11, the lower insulating film 9 is omitted, the data line 4 including the drain electrode 17 is provided on the upper surface of the third reflective film 8c, and the fourth reflective film The source electrode 16 may be provided on the upper surface of 8d. In this case, a first reflective film 8 a (not shown) is provided on the upper surface of the thin film transistor substrate 2 below the scanning line 3 excluding the gate electrode 10.

  Further, as in the eighth embodiment of the present invention shown in FIG. 12, the data line 4 and the source electrode 16 including the drain electrode 17 are replaced with the second reflective film 8b (and the thin film transistor substrate under the scanning line 3 excluding the gate electrode 10). 2 may be formed of a highly reflective metal such as silver or a silver alloy together with the first reflective film 8a) provided on the upper surface of 2.

1 is a cross-sectional view of a main part of a liquid crystal display device as a first embodiment of the present invention. FIG. 2 is a partially transparent plan view of a thin film transistor panel of the liquid crystal display device shown in FIG. 1. The top view shown in order to demonstrate the reflecting film etc. which are shown in FIG.1 and FIG.2. Sectional drawing of the principal part of the liquid crystal display device as 2nd Embodiment of this invention. FIG. 5 is a transmission plan view of a part of the thin film transistor panel of the liquid crystal display device shown in FIG. 4. The top view shown in order to demonstrate the reflecting film shown in FIG. 4 and FIG. Sectional drawing of the principal part of the liquid crystal display device as 3rd Embodiment of this invention. Sectional drawing of the principal part of the liquid crystal display device as 4th Embodiment of this invention. Sectional drawing of the principal part of the liquid crystal display device as 5th Embodiment of this invention. Sectional drawing of the principal part of the liquid crystal display device as 6th Embodiment of this invention. Sectional drawing of the principal part of the liquid crystal display device as 7th Embodiment of this invention. Sectional drawing of the principal part of the liquid crystal display device as 8th Embodiment of this invention.

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 8a, 8b, 8c, 8d 1st-4th reflective film 9 Lower layer insulating film 10 Gate electrode 11 Gate insulating film 12 Semiconductor thin film 13 channel protective film 14, 15 ohmic contact layer 16 source electrode 17 drain electrode 18 overcoat film 20 alignment film 21 polarizing plate 31 counter panel 32 counter substrate 33 black matrix 34 color filter 35 counter electrode 36 alignment film 37 polarizing plate 41 liquid crystal 42 Backlight 43 Light guide plate 44 Reflective layer

Claims (9)

A thin film transistor panel and a counter panel disposed on the thin film transistor panel are bonded to each other through a sealing material, a liquid crystal is sealed between the two panels inside the sealing material, and a backlight is disposed under the thin film transistor panel. In the liquid crystal display device
The thin film transistor panel is:
A thin film transistor substrate;
A first reflective film formed on an upper surface of the thin film transistor substrate;
An insulating film provided to cover the thin film transistor substrate including the first reflective film;
A thin film transistor provided on the insulating film and having a gate electrode, a source electrode and a drain electrode;
A scanning line provided on the insulating film and connected to the gate electrode;
A data line provided on the insulating film and connected to the drain electrode;
A pixel electrode provided on the insulating film and connected to the source electrode;
With
The first reflective film is provided at least under the scan line and the data line, and is provided separately from each other.
A liquid crystal display device characterized by the above. In the invention of claim 1,
A liquid crystal display device, wherein a second reflective film is provided separately from the first reflective film under the source electrode. In the invention of claim 2,
The liquid crystal display device, wherein the second reflective films are provided separately from each other. In the invention of claim 2 ,
An auxiliary capacitance line is further provided on the insulating film , and a third reflective film is provided separately from the first reflective film under the auxiliary capacitance line. In the invention of claim 4,
The liquid crystal display device, wherein the third reflective film is provided separately from each other. In the invention of claim 4,
The liquid crystal display device, wherein the first reflective film, the second reflective film, and the third reflective film are formed in the same layer. In the invention of claim 6,
The liquid crystal display device, wherein the first reflective film, the second reflective film, and the third reflective film contain silver or a silver alloy. In the invention according to any one of claims 1 to 7,
The liquid crystal display device, wherein the thin film transistor is an inverted stagger type. In the invention according to any one of claims 1 to 7,
The liquid crystal display device, wherein the thin film transistor is a staggered type.

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