JP2008040189A - Transflective liquid crystal display device - Google Patents

Abstract

In an IPS transflective liquid crystal display device in which a reflective portion has a normally white characteristic, the drive voltage of the reflective portion is lowered and the contrast of the reflective portion is improved.
A liquid crystal display panel having a pair of substrates and a liquid crystal sandwiched between the pair of substrates, the liquid crystal display panel having a plurality of subpixels each having a transmissive portion and a reflective portion, Each sub-pixel of the plurality of sub-pixels includes a pixel electrode formed on one of the pair of substrates and a first counter electrode formed on the one substrate, and the pixel A transflective liquid crystal display device for driving the liquid crystal by generating an electric field by using an electrode and the first counter electrode, wherein the transflective liquid crystal display device is opposed to a reflective portion of each subpixel of the other substrate of the pair of substrates. A second counter electrode is formed in the region.
[Selection] Figure 1

Description

  The present invention relates to a transflective liquid crystal display device, and more particularly to an IPS transflective liquid crystal display device.

An IPS liquid crystal display device is known as a liquid crystal display device. (See Patent Document 1 and Patent Document 2 below.) In this IPS liquid crystal display device, a pixel electrode and a counter electrode are formed on the same substrate, an electric field is applied between them, and the liquid crystal is rotated in the plane of the substrate. , Do light and dark control. For this reason, there is a feature that the density of the display image does not invert when the screen is viewed obliquely.
In order to make use of this feature, for example, the following Patent Document 3 proposes to construct a transflective liquid crystal display device using an IPS liquid crystal display device.
The transflective liquid crystal display device has a transmissive part and a reflective part in one subpixel, and is mainly used as a display for portable devices.
Note that Patent Document 1 described above describes that the second counter electrode is formed on the substrate side facing the substrate on which the pixel electrode and the counter electrode are formed. Patent Document 2 described above describes forming an electrode for forming a capacitor element below the pixel electrode through an interlayer insulating film. However, what is described in Patent Literature 1 and Patent Literature 2 is a totally transmissive liquid crystal display device, and Patent Literature 1 and Patent Literature 2 do not disclose a transflective liquid crystal display device.

However, when a transflective liquid crystal display device is configured using an IPS liquid crystal display device, if the retardation plate is not used, for example, when the transmission portion is normally black, the reflection portion is normally white. There is a problem that light and dark are reversed between the transmission part and the reflection part.
In order to solve the above-mentioned problems, the present applicant has already filed a transflective liquid crystal display device having a novel pixel structure. (See Patent Document 4 below)
In Patent Document 3, the pixel electrode and the counter electrode are formed on the same insulating film in the transmissive portion, and the pixel electrode and the counter electrode are formed on the reflective portion with an interlayer insulating film interposed therebetween. However, it does not disclose the novel pixel structure described in Patent Document 4 described above.
In the transflective liquid crystal display device described in Patent Document 4, as the pixel structure of each sub-pixel, the counter electrode is made independent between the transmissive part and the reflective part with respect to the pixel electrode common to the transmissive part and the reflective part. By applying different reference voltages (opposite voltage or common voltage), it is possible to prevent light and darkness from being reversed between the transmission part and the reflection part.
Further, in the transflective liquid crystal display device described in Patent Document 4, the transmissive portion has a normally black characteristic (black display when no voltage is applied), and the reflective portion has a normally white characteristic (a state where no voltage is applied). In white).

As prior art documents related to the invention of the present application, there are the following.
JP-A-11-231344 JP 2002-023185 A JP 2003-207795 A Japanese Patent Application No. 2005-322049

As described above, in the transflective liquid crystal display device described in Patent Document 4, since the reflecting portion has a normally white characteristic, in order to display black in the reflecting portion, the pixel electrode is disposed between the counter electrode and the counter electrode. Although it is necessary to increase the drive voltage to be applied, it is assumed that switching to black is not sufficiently performed in a portion where an electric field is difficult to be applied, and a white portion remains and the contrast of the reflection portion is lowered.
Further, not only the transflective liquid crystal display device described in Patent Document 4, but an IPS transflective liquid crystal display device in which both the transmissive part and the reflective part are normally black, or only the reflective part has a normally white characteristic. In the transflective liquid crystal display device of the IPS system, it is desired to make the voltage-luminance characteristics of the transmissive part and the reflective part close to each other in order to reduce the driving voltage and eliminate the unnaturalness of display.
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide an IPS transflective liquid crystal display device in which the reflective portion has a normally white characteristic. An object of the present invention is to provide a technique capable of lowering the driving voltage and improving the contrast of the reflecting portion.
Another object of the present invention is to provide an IPS transflective liquid crystal display device in which both the transmissive part and the reflective part have a normally black characteristic, or an IPS semitransparent liquid crystal in which only the reflective part has a normally white characteristic. It is an object of the present invention to provide a technique capable of lowering the driving voltage and bringing the voltage-luminance characteristics of the transmission part and the reflection part closer to each other in the display device.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
(1) A liquid crystal display panel having a pair of substrates and a liquid crystal sandwiched between the pair of substrates, the liquid crystal display panel having a plurality of subpixels each having a transmissive portion and a reflective portion, Each subpixel of the plurality of subpixels includes a pixel electrode formed on one of the pair of substrates and a first counter electrode formed on the one substrate, and the pixel electrode A transflective liquid crystal display device for driving the liquid crystal by generating an electric field with the first counter electrode, and facing the reflective portion of each subpixel of the other substrate of the pair of substrates The second counter electrode is formed only in the region.
(2) In (1), the first counter electrode of the reflective portion is a strip-shaped electrode, and has an interlayer insulating film formed on the strip-shaped first counter electrode of the reflective portion. The pixel electrode of the reflection part is formed on the interlayer insulating film.

(3) In (1) or (2), the pixel electrode and the second counter electrode of the reflecting portion are comb-like electrodes, and the direction is perpendicular to the main surface of the liquid crystal display panel. When the comb-like electrode of the pixel electrode of the reflective portion and the comb-like electrode of the second counter electrode are projected onto the one substrate, the gap between the comb electrodes of the second counter electrode In addition, a comb electrode of the pixel electrode of the reflection portion is located.
(4) In any one of (1) to (3), the pixel electrode of the transmissive part and the first counter electrode of the transmissive part are comb-like electrodes.
(5) In (4), the comb electrode of the pixel electrode of the transmission part and the comb electrode of the first counter electrode of the transmission part are formed on the same insulating film. The comb electrodes of the pixel electrode of the transmissive portion are positioned between the comb electrodes of the first counter electrode of the transmissive portion.
(6) In any one of (1) to (3), the first counter electrode of the transmissive portion is a strip-shaped electrode, and is formed on the strip-shaped first counter electrode of the transmissive portion. The pixel electrode of the transmissive portion is formed on the interlayer insulating film.
(7) In (6), the pixel electrode of the transmissive part is a comb-like electrode.

(8) A liquid crystal display panel having a pair of substrates and a liquid crystal sandwiched between the pair of substrates, the liquid crystal display panel having a plurality of subpixels each having a transmissive portion and a reflective portion, Each subpixel of the plurality of subpixels includes a pixel electrode formed on one of the pair of substrates and a first counter electrode formed on the one substrate, and the pixel electrode And the first counter electrode, a liquid crystal display device that drives the liquid crystal by generating an electric field, wherein the pixel electrode of the transmissive portion and the first counter electrode of the transmissive portion are: A comb-like electrode having an interlayer insulating film formed on the first counter electrode of the transmissive portion, wherein the pixel electrode of the transmissive portion is formed on the interlayer insulating film, and the liquid crystal display From the direction perpendicular to the main surface of the panel, When the pixel electrode and the first counter electrode of the transmissive part are projected onto the one substrate, each comb electrode of the pixel electrode of the transmissive part and the first counter electrode of the transmissive part At least a part of each of the comb electrodes is overlapped.
(9) In (8), a second counter electrode is formed in a region facing the reflecting portion of each subpixel of the other substrate of the pair of substrates.
(10) In (8) or (9), the first counter electrode of the reflective portion is a strip-shaped electrode, and an interlayer insulating film formed on the strip-shaped first counter electrode of the reflective portion And the pixel electrode of the reflective portion is formed on the interlayer insulating film.
(11) In (10), the pixel electrode of the reflecting portion is a comb-like electrode.

(12) In any one of (8) to (11), the pixel electrode and the second counter electrode of the reflective portion are comb-shaped electrodes, and are orthogonal to the main surface of the liquid crystal display panel. When the comb-like electrode of the pixel electrode of the reflective portion and the comb-like electrode of the second counter electrode are projected onto the one substrate, each comb tooth of the second counter electrode Between the electrodes, each comb electrode of the pixel electrode of the reflecting portion is located.
(13) In (8), the pixel electrode of the reflective portion is a comb-like electrode, the first counter electrode of the reflective portion is a strip-like electrode, and the strip-like shape of the reflective portion is An inter-layer insulating film formed on the first counter electrode, wherein the comb-like electrode of the pixel electrode of the reflecting portion is formed on the inter-layer insulating film, and the reflecting portion is formed on the inter-layer insulating film; A second counter electrode formed in the region, wherein the second counter electrode of the reflecting portion is a comb-like electrode, and each comb-tooth electrode of the second counter electrode of the reflecting portion is In between, each comb electrode of the pixel electrode of the reflection part is located.
(14) In (3), (12), or (13), the two comb-tooth electrodes of the second counter electrode in which the comb-tooth electrode of the pixel electrode of the reflecting portion is positioned between one comb tooth When the electrode and the other comb-teeth electrode are used, the distance between the comb-teeth electrode of the pixel electrode of the reflection part and the one comb-teeth electrode of the second counter electrode, and the reflection part The distance between the comb electrode of the pixel electrode and the other comb electrode of the second counter electrode is the same.

(15) In (14), each of the comb electrodes of the second counter electrode and each of the comb electrodes of the pixel electrode of the reflective portion have the same electrode width.
(16) In (3), (12), (13), (14) or (15), the comb electrode of the second counter electrode is also formed at the boundary of the adjacent subpixels.
(17) In any one of (1) to (16), the pixel electrode of the transmissive part and the pixel electrode of the reflective part are both comb-like electrodes, and the pixel electrode of the reflective part The interval between the comb electrodes is wider than the interval between the comb electrodes of the pixel electrode of the transmission portion.
(18) In any one of (1) to (17), the same drive voltage is applied to the first counter electrode and the second counter electrode of the reflecting section.
(19) In any one of (1) to (18), in each of the subpixels, the pixel electrode is common to the transmissive part and the reflective part, and the first counter electrode is the transmissive part. The reflecting portions are independent of each other.

(20) In (19), in each of the sub-pixels, a potential applied to one of the first counter electrodes of the transmissive portion or the reflective portion is higher than a potential applied to the pixel electrode. The potential applied to the first counter electrode of the other of the transmissive portion or the reflective portion is lower than the potential applied to the pixel electrode.
(21) In any one of (1) to (20), when two adjacent display lines are set as one display line and the other display line, the transmission portion of each sub-pixel of the one display line Different reference voltages are applied to the first counter electrode of the one display line and the first counter electrode of the reflecting portion of each of the sub-pixels of the one display line, so that each of the sub-lines of the one display line is The same reference voltage is applied to the first counter electrode of the reflective portion of the pixel and the first counter electrode of the transmissive portion of each sub-pixel of the other display line.
(22) In (21), the first counter electrode of the reflective portion in each subpixel of the one display line, and the first of the transmissive portion in each subpixel of the other display line. The counter electrode is a common electrode.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
(1) According to the present invention, in an IPS transflective liquid crystal display device having a normally white characteristic in the reflective portion, the drive voltage of the reflective portion can be lowered and the contrast of the reflective portion can be improved. It becomes possible.
(2) According to the present invention, an IPS-type transflective liquid crystal display device in which both the transmissive part and the reflective part have normally black characteristics, or an IPS-type semi-transmissive liquid crystal display in which only the reflective part has normally white characteristics. In the apparatus, the drive voltage can be lowered, and the voltage-luminance characteristics of the transmissive part and the reflective part can be made closer to each other.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same functions are given the same reference numerals, and repeated explanation thereof is omitted.
[Transflective liquid crystal display device as a premise of the present invention]
FIG. 14 is a plan view showing an electrode structure of a subpixel as an example of a transflective liquid crystal display device as a premise of the present invention. 15 is a cross-sectional view of a main part showing a cross-sectional structure along the AA ′ connection line of FIG. 14, and FIG. 16 is a cross-sectional view of a main part showing a cross-sectional structure along the BB ′ connection line of FIG. FIG. 17 is a cross-sectional view of a principal part showing a cross-sectional structure along the CC ′ connection line of FIG. 14.
In FIG. 14, reference numeral 30 denotes a transmissive portion constituting a transmissive liquid crystal display panel, and reference numeral 31 denotes a reflective portion constituting a reflective liquid crystal display panel.
A pair of glass substrates (SUB1, SUB2) are provided with the liquid crystal layer (LC) interposed therebetween. Here, the main surface side of the glass substrate (SUB2) is the observation side.
On the liquid crystal layer side of the glass substrate (SUB2), in order from the glass substrate (SUB2) to the liquid crystal layer (LC), a black matrix (BM) and a color filter layer (FIR), an insulating film 15, a step forming layer (MR) ), An alignment film (OR2) is formed. A polarizing plate (POL2) is formed outside the glass substrate (SUB2).

In addition, on the liquid crystal layer side of the glass substrate (SUB1), an interlayer insulating film (12A to 12D), an interlayer insulating film 13, a counter electrode (CT), and a liquid crystal layer (LC) are sequentially arranged from the glass substrate (SUB1). A reflective electrode (RAL), an interlayer insulating film 11, a pixel electrode (PIX), and an alignment film (OR1) are formed. A polarizing plate (POL1) is also formed outside the glass substrate (SUB1).
The pixel electrode (PIX) and the counter electrode (CT) are made of a transparent conductive film such as ITO (Indium Tin Oxide), for example. The counter electrode (CT) is formed in a planar shape, and the pixel electrode (PIX) and the counter electrode (CT) are overlapped with each other via the interlayer insulating film 11, thereby forming a storage capacitor. Yes.
The step forming layer (MR) is for adjusting the cell gap length (d) of the liquid crystal layer (LC) of the reflective portion so that the optical path length of the light in the reflective portion becomes an optical path length corresponding to λ / 4 wavelength. Is. Further, the reflective electrode (RAL) is made of, for example, a metal film of aluminum (Al), but is not limited to this. For example, the reflective electrode (RAL) has a two-layer structure of lower layer molybdenum (Mo) and upper layer aluminum (Al). There may be.

As shown in FIG. 14, the pixel electrode (PIX) includes a pixel electrode 51 of the transmissive part 30, a pixel electrode 52 of the reflective part 31, and a strip-shaped connecting part 53 formed between the pixel electrode 51 and the pixel electrode 52. And have. As shown in FIG. 14, the pixel electrode 51 and the pixel electrode 52 are each formed in a comb shape, and the pixel electrode 51 and the pixel electrode 52 are formed at a predetermined pitch. Further, each of the portions indicated by dotted line frames a and b represents one subpixel.
Here, a part of the interlayer insulating film (11, 13, 12D) in the strip-like connecting portion 53 constituting a part of the pixel electrode (PIX) is a through for applying a video voltage to the pixel electrode (PIX). A hole (TH) is formed.
In FIG. 14, FIG. 15, and other corresponding diagrams, a plurality of scanning lines (or gate lines) (G) and a plurality of video lines (drain lines) (D) intersecting the plurality of scanning lines are shown. An active matrix is formed by active elements (for example, thin film transistors) formed corresponding to each subpixel, but the illustration is omitted. Further, contact holes are formed as necessary, but these are not shown. Further, although the counter electrode (CT) is electrically connected to the counter electrode (CT) of a subpixel in an adjacent column (not shown), the connection structure is also not shown.

Within one subpixel, the pixel electrode (PIX) is common, but the counter electrode (CT) is independent between the transmissive part 30 and the reflective part 31. That is, the counter electrode (CT) is divided into two parts for the transmission part and the reflection part.
In FIG. 14, the counter electrode (CT) of the reflective portion 31 in one display line (a display line having a subpixel indicated by a in FIG. 14) of the two adjacent display lines and the other display line (FIG. 14). 14 shows a case where the counter electrode (CT) of the transmissive portion 30 in the display line having a subpixel indicated by 14b is configured by a common electrode. Further, an arrow D in FIG. 14 indicates the scanning direction.
As shown in FIG. 18, different reference voltages are applied to the counter electrode (CT) of the transmission unit 30 and the counter electrode (CT) of the reflection unit 31 within one subpixel.
For example, in the subpixel indicated by a in FIG. 14, a high level (hereinafter, H level) reference voltage (V-CT-H) is applied to the counter electrode (CT) of the transmission unit 30, and A low level (hereinafter referred to as L level) reference voltage (V-CT-L) is applied to the counter electrode (CT).

Further, in the sub-pixel shown by a in FIG. 14, the pixel electrode (PIX) has a negative polarity when viewed through the transmissive portion 30 and a positive polarity when viewed through the reflective portion 31 (V−). PX) is applied. The negative polarity here means that the potential of the pixel electrode (PIX) is lower than the potential of the counter electrode (CT), and whether the potential of the pixel electrode (PIX) is larger or smaller than 0V. Does not matter. Similarly, the positive polarity here means that the potential of the pixel electrode (PIX) is higher than the potential of the counter electrode (CT), and the potential of the pixel electrode (PIX) is larger or smaller than 0V. It doesn't matter.
Similarly, in the subpixel indicated by b in FIG. 14, an L-level reference voltage (V-CT-L) is applied to the counter electrode (CT) of the transmission unit 30, and the counter electrode (CT) of the reflection unit 31. Is applied with an H-level reference voltage (V-CT-H). In the sub-pixel shown by b in FIG. 14, the pixel electrode (PIX) has a positive video voltage (V− when viewed through the transmissive portion 30 and a negative video voltage when viewed through the reflective portion 31. PX) is applied.
Here, the video voltage (V-PX) applied to the pixel electrode (PIX) is between the H level reference voltage (V-CT-H) and the L level reference voltage (V-CT-L). Potential.

Therefore, in the sub-pixels indicated by a and b in FIG. 14, the potential difference (Va in FIG. 18) between the pixel electrode (PIX) and the counter electrode (CT) is large in the transmissive portion 30, and in the reflective portion 31. The potential difference (Vb in FIG. 18) between the pixel electrode (PIX) and the counter electrode (CT) becomes small.
Therefore, when the potential shown in FIG. 18 is applied, the transmissive portion 30 becomes bright because the potential difference Va between the pixel electrode (PIX) and the counter electrode (CT) is large. At this time, since the potential difference Vb between the pixel electrode (PIX) and the counter electrode (CT) is small, the reflection unit 31 is similarly brightened.
Then, in the transmission unit 30, the potential of the pixel electrode (PIX) (the potential of the video signal) is changed to a potential different from that in FIG. 18, and the potential difference Va between the pixel electrode (PIX) and the counter electrode (CT) is further increased. When the value is increased, the potential difference Vb between the pixel electrode (PIX) and the counter electrode (CT) is further reduced in the reflection part 31, so that both the transmission part 30 and the reflection part 31 become brighter.

Conversely, in the transmission unit 30, the potential of the pixel electrode (PIX) (the potential of the video signal) is changed to a potential different from that in FIG. 18, and the potential difference Va between the pixel electrode (PIX) and the counter electrode (CT) is changed. When the size is reduced, the potential difference Vb between the pixel electrode (PIX) and the counter electrode (CT) is increased in the reflection section 31, so that both the transmission section 30 and the reflection section 31 are dark.
As described above, the counter electrode (CT) is divided into two for the transmissive portion and the reflective portion within one subpixel, and the counter electrode (CT) of the transmissive portion 30 and the counter electrode (CT) of the reflective portion 31 are divided. In addition, a reference voltage having a reverse polarity (here, reverse polarity means that when one is at an H level, the other is at an L level) is applied. 30 and the reflection part 31 can prevent light and darkness from being reversed. That is, although the transmission part 30 is normally black and the reflection part 31 is normally white, by devising the voltage applied to the counter electrode (CT) of the reflection part 31, the problem of light / dark reversal is solved. It has been solved.

[Example 1]
FIG. 1 is a plan view showing an electrode structure of a subpixel of a transflective liquid crystal display device according to a first embodiment of the present invention, and a region surrounded by an alternate long and short dash line in FIG. 1 is one subpixel region (1SPIX). . 2A is a principal part sectional view showing a sectional structure along the line AA ′ in FIG. 1, and is a principal part sectional view showing a structure of the reflecting part 31. Further, FIG. 2B is a principal part sectional view showing a sectional structure along the line BB ′ in FIG. 1, and a principal part sectional view showing a structure of the transmission part 30.
The main feature of the present embodiment is that the second counter electrode (CT2) is formed on the glass substrate (SUB2) side.
As shown in FIG. 2 (a), in the present embodiment, the reflecting portion 31 includes a strip-shaped transparent counter electrode (CT) formed on the glass substrate (SUB1) and the strip-shaped counter electrode (CT). That is, it has a reflective electrode (RAL) electrically connected to the strip-shaped counter electrode (CT).
Further, on the interlayer insulating film 11 having a thickness t covering the reflective electrode (RAL), a comb-shaped pixel electrode (PIX) having a width of each comb-shaped electrode Ws is provided. Here, the number of the comb electrodes of the pixel electrode (PIX) is one or more, but FIG. 1 illustrates the case of three.
The pixel electrode (PIX) is electrically connected to a source electrode of a thin film transistor (TFT) (not shown).

Further, on the glass substrate (SUB2) side, there is a comb-shaped transparent second counter electrode (CT2) in which the width of each comb-tooth electrode is Wc. Here, the number of the comb electrodes of the second counter electrode (CT2) needs to be two or more. As shown in FIG. 1, the second counter electrode (CT2) is also disposed on the boundary between adjacent subpixels.
Further, as shown in FIG. 2A, when the electrode forming surface side of the glass substrate (SUB2) and the electrode forming surface side of the glass substrate (SUB1) are arranged to face each other at a distance d, the pixel electrode Each comb tooth electrode of (PIX) is located between each comb tooth electrode of the second counter electrode (CT2), and the second counter electrode closest to the end of each comb tooth electrode of the pixel electrode (PIX). The pattern is such that the distance L extends to the end of the electrode (CT2).
Further, as shown in FIG. 2B, the transmission part 30 has a band-shaped counter electrode (CT) formed on the glass substrate (SUB1) and a thickness t that covers the band-shaped counter electrode (CT). A comb-like pixel electrode (PIX) is provided on the interlayer insulating film 11. Here, one or more comb-teeth electrodes of the pixel electrode (PIX) are necessary, but FIG. 1 shows the case of four.
Therefore, in this embodiment, the interval between the comb electrodes of the pixel electrode (PIX) of the transmissive part 30 is narrower than the interval of the comb electrodes of the pixel electrode (PIX) of the reflector 31.

In the target subpixel, the counter electrode (CT) of the transmissive part 30 is not electrically connected to the counter electrode (CT) of the reflective part 31, but the pixel electrode (PIX) of the transmissive part 30. And the pixel electrode (PIX) of the reflecting portion 31 are electrically connected.
The reflective electrode (RAL) of the reflective unit 30 of the subpixel of interest is electrically connected to the counter electrode (CT) of the transmissive unit 30 of the upper adjacent subpixel not shown in FIG. The counter electrode (CT) of the transmissive portion 30 of the subpixel is electrically connected to the reflective electrode (RAL) of the reflective portion 31 of the lower adjacent subpixel not shown in FIG. .
The second counter electrode (CT2) on the glass substrate (SUB2) side is applied with a potential equal to or substantially equal to the reflective electrode (RAL) of the reflective portion 31.
In this embodiment, the scanning direction is performed from the upper side to the lower side in FIG. 1 or from the lower side to the upper side in FIG.
Alignment films (OR1, OR2) are formed on the surfaces of the glass substrate (SUB1) and the glass substrate (SUB2) on the liquid crystal layer (LC) side, respectively, and extend in the extending direction of the comb electrode of the pixel electrode (PIX). On the other hand, the orientation process is performed in the direction of angle φ0 (C in FIG. 1).

The sub-pixels of this embodiment configured as described above include not only the fringe electric field from each comb electrode of the pixel electrode (PIX) to the reflection electrode (RAL) but also glass from each comb electrode of the pixel electrode (PIX). Since an electric field directed to the second counter electrode (CT2) on the substrate (SUB2) side can also be generated, a lateral electric field parallel to the substrate surface can be applied over the entire liquid crystal layer.
This effect has been confirmed by comparison with a comparative example, and will be described below.
FIG. 3 shows a cross-sectional view of the subpixel structure of the comparative example.
The comparative example shown in FIG. 3 is obtained by removing the second counter electrode (CT2) on the glass substrate (SUB2) side in the cross-sectional structure of FIG. 2 (a), and the comb electrode of the pixel electrode (PIX). The width is Ws, and the interval between the comb electrodes of the pixel electrode (PIX) is (2 × L + Wc).
In FIG. 4, arrangement | positioning of the optical member in a present Example and a comparative example is shown.
On the display surface side of the glass substrate (SUB2), an absorption axis (A in FIG. 4) having an absorption axis (A in FIG. 4) in a direction orthogonal to the alignment processing direction (B in FIG. 4) of the alignment film (OR2) on the glass substrate (SUB2) side. Two polarizing plates (POL2) are arranged. On the side opposite to the glass substrate (SUB2) side of the glass substrate (SUB1), parallel to the alignment treatment direction (C in FIG. 4) of the alignment film (OR1) on the glass substrate (SUB1) side, and a second polarizing plate ( A first polarizing plate (POL1) having an absorption axis (D in FIG. 4) is arranged in a direction orthogonal to the absorption axis direction (POL in FIG. 4A).

About the above structure, the liquid crystal alignment with respect to reflection display and optical simulation were implemented on the calculation conditions shown in Table 1. FIG. In Table 1, CASE1 and CASE2 are Example 1-1, Example 1-2, CASE3, and CASE4 are Comparative Example 1-1 and Comparative Example 1-2, and RFig is CASE1 (implemented). Reference structure diagrams of Example 1-1), CASE2 (Example 1-2), CASE3 (Comparative Example 1-1), and CASE4 (Comparative Example 1-2) are shown.
For CASE 1 (Example 1-1), CASE 2 (Example 1-2), CASE 3 (Comparative Example 1-1), and CASE 4 (Comparative Example 1-2), the electrode width Ws = Wc = 2.5 μm and the electrode spacing L = 2.5 μm, liquid crystal layer thickness d = 2.4 μm, liquid crystal dielectric anisotropy Δε = 7.0, liquid crystal birefringence Δn = 0.08, pretilt angle θ = 3.0 °, alignment treatment direction φ0 = 15 Set to °.
In CASE 1 (Example 1-1) and CASE 3 (Comparative Example 1-1), assuming that an organic film is used as the interlayer insulating film 11, the thickness t of the interlayer insulating film 11 is 1.4 μm, and the interlayer insulation is used. The relative dielectric constant ε of the film 11 is set to 3.3.
In CASE 2 (Example 1-2) and CASE 4 (Comparative Example 1-2), assuming that silicon nitride (SiN) is used as the interlayer insulating film 11, the thickness t of the interlayer insulating film 11 is 0.8 μm, The relative dielectric constant ε of the interlayer insulating film 11 is set to 6.7.
As the applied voltage, the second counter electrode (CT2) and the reflective electrode were set to 0V, and the pixel electrode (PIX) was calculated from 0V to 8V in 0.5V steps.
The simulation results are shown in FIGS.

FIG. 5 is a diagram showing voltage (V) -reflectance (RF) characteristics obtained by calculation, where ◆ is CASE 1 (Example 1-1), ◇ is CASE 3 (Comparative Example 1-1), and ■ is CASE2 (Example 1-2) and □ indicate CASE4 (Comparative Example 1-2).
As can be seen from FIG. 5, whether the organic film is used as the interlayer insulating film 11 or SiN is used, the voltage that sinks the reflectance most can be lowered in this embodiment compared to the comparative example. You can see that
FIG. 6 is a diagram showing the maximum contrast ratio obtained from the voltage-reflectance characteristics and the drive voltage giving the maximum contrast, where CRmax represents the maximum contrast, and Vmin is the drive voltage at which CRmax is obtained, that is, the black display reflectivity. Represents the driving voltage that sinks the most.
As can be seen from FIG. 6, the drive voltage (Vmin) can be reduced and the maximum contrast (CRmax) can also be improved.
When actually used as a liquid crystal display device, since it is driven with a certain voltage from the outside, it is necessary to compare the contrast ratio at the same applied voltage.
Assuming 4V and 5V as general applied voltages, the maximum contrast ratio (CRmax) obtained from the voltage-reflectance characteristics, the contrast ratio when applying 4V (CR-4V), and the contrast ratio when applying 5V ( CR-5V) are summarized in Table 2.
As can be seen from Table 2, not only the maximum contrast ratio but also the 4V contrast ratio and the 5V contrast ratio are improved.
From these results, the structure of the present embodiment allows a lateral electric field parallel to the substrate surface to be applied over the entire liquid crystal layer, so that the driving voltage is reduced as compared with the case where the structure is applied to the reflective portion 31 having the conventional structure. It can be seen that the effect of improving the contrast of the reflective display can be obtained.

Furthermore, the voltage-transmittance characteristics in the transmission part 30 were compared.
Table 3 shows the liquid crystal alignment for the transmissive display and the calculation conditions for the optical simulation. In Table 3, R-Display indicates reflective display, T-Display indicates transmissive display, and CASE5 and CASE7 indicate reflective display in Example 1-2 and transmissive display in Example 1-2. CASE 6 is the reflective display of Comparative Example 1-2. Furthermore, RFig shows a reference structure diagram of CASE5 (Example 1-2), CASE6 (Comparative Example 1-2), and CASE7 (Example 1-2).
Since it is desirable for manufacturing the panel that the transmissive part 30 and the reflective part 31 share the interlayer insulating film 11, the liquid crystal material, and the alignment treatment, CASE5 (Example 1-2) and CASE6 (comparison) are used here. As assumed in Example 1-2), the thickness t of the interlayer insulating film 11 is 0.8 μm, the relative dielectric constant ε of the interlayer insulating film 11 is 6.7, the liquid crystal dielectric anisotropy Δε is 7.0, Liquid crystal birefringence Δn = 0.08, pretilt angle θ = 3.0 °, and alignment treatment direction φ0 = 15 ° were set as the setting conditions for transmissive display (CASE 7).
As shown in FIG. 2B, the cross-sectional structure of the transmission part 30 is a structure in which the second counter electrode (CT2) is not provided on the glass substrate (SUB2) side, and only the reflection part 31 has a glass substrate (SUB2). ) Side is provided with a transparent liquid crystal layer thickness adjusting layer (step forming layer (MR)), the liquid crystal layer (LC) thickness d ′ = 4.0 μm of the transmissive portion 30, and the liquid crystal layer (LC) of the reflective portion 31. ) Thickness d = 2.4 μm. Further, the width Ws of the comb electrode of the pixel electrode (PIX) of the transmission part 30 was set to 2.5 μm, and the interval was set to 7.5 μm.

FIG. 7 is a graph showing voltage (V) -transmittance (TF) characteristics obtained by calculation. Voltage (V) -reflectance characteristics (Example 1-2 and Comparative Example 1-2 shown in FIG. 5) The calculation results of (RF) are also shown.
As shown in FIG. 7A, the driving voltage of the transmission unit 30 is preferably used in the range from about 0 V where the transmittance is minimum to about 4.5 V where the transmittance is maximum or less.
On the other hand, in the case of CASE 6 (Comparative Example 1-2), the driving voltage of the reflecting portion is as high as about 5.5 V, as shown in FIG. 7B, with an applied voltage that can sufficiently sink the black display reflectance. .
On the other hand, in the case of CASE 5 (Example 1-2), the applied voltage that can sufficiently sink the black display reflectance is about 4.5 V as shown in FIG. 30 is the same drive voltage range.
In the transflective liquid crystal display device according to the present embodiment, the driving voltage range of the reflective portion 31 and the transmissive portion 30 must match, so the graph is viewed in a limited range that matches the driving voltage range with the transmissive portion 30. Compared with CASE2 (Comparative Example 1-2), CASE1 (Example 1-2) not only improves the contrast ratio of the reflection part 31, but also the shape of the voltage-reflectance characteristics of the reflection part 31 is the transmission part. It is approaching a symmetrical shape with respect to the shape of 30 voltage-transmittance characteristics. For this reason, in actual use conditions in which the transmission unit 30 and the reflection unit 31 are viewed at the same time, it is possible to reduce a mismatch in the relationship of brightness to gradation.

The above simulation results are for confirming the effect of the subpixel structure of the present embodiment, and are not limited to specific conditions. That is, the parameters shown in Table 1 and Table 3 have a degree of freedom and can be changed according to the design necessity.
FIG. 8 is a diagram for explaining a subpixel of a modification of the transflective liquid crystal display device of this embodiment, and FIG. 8A is a plan view showing an electrode structure of the subpixel. FIG. 8B is a main part sectional view showing a cross-sectional structure along the line EE ′ in FIG. 8A, and a main part sectional view showing the structure of the transmission part 30.
In FIG. 1, the electrode structure of the transmissive portion 30 includes a strip-shaped counter electrode (CT) and a comb-shaped pixel electrode (PIX) formed on the interlayer insulating film 11 formed on the strip-shaped counter electrode (CT). However, in the modification shown in FIG. 8, the electrode structure of the transmission part 30 is a comb-shaped counter electrode (CT1) formed on the interlayer insulating film 11 and a comb-shaped pixel electrode. (PIX).
FIG. 8B is a sub-pixel cross-sectional structure of the transmissive portion 30, and has a comb-tooth shape on the interlayer insulating film 11 having a thickness t covering a thin film transistor (TFT) (not shown) on the glass substrate (SUB 1) side. At least one pixel electrode (PIX) is formed, and at least two comb-shaped counter electrodes (CT1) are formed. The comb-shaped electrodes of the pixel electrode (PIX) are connected to the counter electrodes (CT1). The pattern is located between the comb electrodes.

The pixel electrode (PIX) is electrically connected to the pixel electrode (PIX) of the reflecting portion 31 and is electrically connected to a source electrode of a thin film transistor (TFT) (not shown).
In FIG. 8A, a region surrounded by an alternate long and short dash line is one sub-pixel region (1SPIX), and the AA ′ cross section in the reflecting portion 31 corresponds to the cross-sectional structure in FIG.
The reflective electrode (RAL) of the subpixel of interest is electrically connected to the counter electrode (CT1) in the transmissive portion 30 of the upper adjacent subpixel not shown in FIG. The counter electrode (CT1) in the transmissive portion 30 of the subpixel is electrically connected to the reflective electrode (RAL) of the adjacent subpixel on the lower side which is not shown in FIG.
By adopting a sub-pixel structure as in this embodiment or a modification thereof, the shape of the voltage-reflectance characteristic of the reflector 31 and the shape of the voltage-transmittance characteristic of the transmissive part 30 are symmetrical in the operation. As a result, the degree of freedom for designing the reflector 31 and the transmissive part 30 so as to substantially match the threshold voltage and the voltage that gives the maximum efficiency is increased.
For this reason, in the actual use conditions in which the transmissive part 30 and the reflective part 31 are viewed at the same time, it is effective to reduce the disagreement in the relationship of the brightness with respect to the gradation and eliminate the unnaturalness of the display.
In the above description, the embodiment in which the present invention is applied to the IPS type transflective liquid crystal display device in which only the reflective portion has a normally white characteristic has been described. However, the present invention is not limited to this, The present invention can also be applied to an IPS transflective liquid crystal display device having a normal structure (both transmissive portion 30 and reflective portion 31 are normally black characteristics).

[Example 2]
FIG. 9 is a plan view showing an electrode structure of a subpixel of the transflective liquid crystal display device according to the second embodiment of the present invention, and a region surrounded by a one-dot chain line in FIG. 9 is one subpixel region (1SPIX). . FIG. 10A is a principal part sectional view showing a sectional structure along the line FF ′ in FIG. 9, and is a principal part sectional view showing the structure of the transmission part 30. Further, FIG. 10B is a principal part sectional view showing a sectional structure along the GG ′ connection line of FIG. 9, and a principal part sectional view showing a structure of the reflecting part 31.
In the present embodiment, a comb-shaped counter electrode (CT1) having a comb-shaped electrode width W is formed on the glass substrate (SUB1) side of the transmission portion 30 and the thickness of the counter electrode (CT1) is covered. A comb-shaped pixel electrode (PIX) having a comb-shaped electrode width W is formed on the interlayer insulating film 11 of t, and the comb-shaped electrode of the pixel electrode (PIX) and the counter electrode (CT1) The comb electrode is at least partially overlapped.
Here, one or more comb electrodes of the counter electrode (CT1) are formed, and one or more comb electrodes of the pixel electrode (PIX) are formed.
The pixel electrode (PIX) is electrically connected to a source electrode of a thin film transistor (TFT) (not shown). Further, the glass substrate (SUB2) and the electrode forming surface side of the glass substrate (SUB1) are arranged to face each other with a distance d ′, and the thickness of the liquid crystal layer (LC) in the transmissive part 30 is d ′.

In the reflection unit 31, the distance between the glass substrate (SUB2) and the glass substrate (SUB1), that is, the thickness of the liquid crystal layer (LC) is d.
In the subpixel of interest, on the glass substrate (SUB1) side of the reflective portion 31, a strip-shaped reflective electrode (RAL) that is not electrically connected to the counter electrode (CT1) of the transmissive portion 30 is formed. The reflective electrode (RAL) is covered with an interlayer insulating film 11, and a comb-like pixel electrode (PIX) is formed on the interlayer insulating film.
Here, one or more comb-shaped electrodes of the pixel electrode (PIX) of the reflecting portion 31 are formed. Further, the pixel electrode (PIX) of the reflection unit 31 and the pixel electrode (PIX) of the transmission unit 30 are electrically connected.
The reflective electrode (RAL) of the subpixel of interest is electrically connected to the counter electrode (CT1) of the transmissive portion of the upper adjacent subpixel not shown in FIG. The transparent counter electrode (CT1) is electrically connected to the reflective electrode (RAL) of the lower adjacent subpixel not shown in FIG.
The scanning direction in this embodiment is performed from the upper side to the lower side or from the lower side to the upper side in FIG.
Alignment films (OR1, OR2) are formed on the surfaces of the glass substrate (SUB1) and the glass substrate (SUB2), respectively, and are oriented in the direction of an angle φ0 with respect to the extending direction of the comb electrode of the pixel electrode (PIX). Processing (C in FIG. 9) is performed.

The effect of the sub-pixel of this embodiment configured as described above will be described with reference to FIG.
In FIG. 10A, when the potential Vs is applied to the pixel electrode (PIX) and the potential Vc is applied to the counter electrode (CT1), the pixel electrode (PIX) and the counter electrode (CT1) are connected with each other between the pixel electrode (PIX) and the counter electrode (CT1). An electric field as shown by a solid line with an arrow is formed.
At this time, if an imaginary plane is considered as the interlayer insulating film intermediate surface 11a at a position t / 2 substantially in the middle of the film thickness direction of the interlayer insulating film 11, the electric field intersects this plane almost perpendicularly, and the interlayer insulating film The potential of the intermediate surface 11a is approximately the potential (Vs + Vc) / 2 between the pixel electrode (PIX) and the counter electrode (CT1).
Therefore, as shown in FIG. 11, when a band-like equivalent counter electrode (CTI) is provided at the position of the interlayer insulating film intermediate surface 11a and its potential is set to Vc ′ = (Vs + Vc) / 2, the liquid crystal layer The state of the electric field applied to (LC) is not different from FIG.
That is, for the liquid crystal layer (LC), in the sub-pixel having the strip-like equivalent counter electrode (CTI) and the pixel electrode (PIX) formed with the interlayer insulating film 11h having the film thickness t / 2 interposed therebetween, the pixel electrode ( PIX) is equivalent to a potential Vs and a strip-like equivalent counter electrode (CTI) is applied with a potential Vc ′ = (Vs + Vc) / 2.

Therefore, the liquid crystal applied voltage in FIG. 11 is Vs−Vc ′ = Vs− (Vs + Vc) / 2 = (Vs−Vc) / 2. Thereby, the change in retardation (Δn · d) of the liquid crystal layer (LC) can be made different between the reflective portion 31 and the transmissive portion 30.
Compared with FIG. 10B showing the sub-pixel structure of the reflective portion 31, the reflective portion 31 is provided between the pixel electrode (PIX) and the counter electrode (CT 1) in the transmissive portion 30. This is because it is driven at about twice the voltage, and the retardation change of the liquid crystal layer (LC) of the reflection portion 31 can be made relatively larger than that of the transmission portion 30.
Due to such an effect, in the subpixel structure having the transmissive part 30 and the reflective part 31 in one subpixel, the shape of the voltage-transmittance characteristic and the shape of the voltage-reflectance characteristic are brought closer to a symmetrical shape, In actual use conditions in which the transmissive part and the reflective part are viewed at the same time, it is possible to reduce the disagreement in the relationship between the brightness and the gradation, thereby eliminating the unnaturalness of the display.

In FIG. 10, a strip-shaped counter electrode (CT) and a pixel electrode (PIX) formed with the interlayer insulating film 11 having a film thickness t interposed therebetween are employed as the electrode structure of the reflective portion 31. The same configuration as that of the reflecting portion 31 in the first embodiment may be adopted.
FIG. 12 is a plan view showing the electrode structure of the subpixels in the first modification of the transflective liquid crystal display device according to the second embodiment of the present invention. The region surrounded by the one-dot chain line in FIG. 1 SPIX).
12 is a cross-sectional structure along the line AA ′ in FIG. 12 (cross-sectional structure of the reflective portion 31). FIG. 2A is a cross-sectional structure along the line FF ′ in FIG. The structure corresponds to FIG.
The configuration of the reflective electrode (RAL) on the glass substrate (SUB1) side and the comb-shaped counter electrode (CT1) is the same as that in FIG. The second counter electrode (CT2) in the reflective portion 31 on the glass substrate (SUB2) side is set to a potential substantially equal to the reflective electrode (RAL) on the glass substrate (SUB1) side.

FIG. 13 is a diagram for explaining an electrode structure of a subpixel according to the second modification of the transflective liquid crystal display device according to the second embodiment of the present invention, and an area surrounded by an alternate long and short dash line is one subpixel area (1SPIX). ).
FIG. 13A is a plan view showing the electrode structure of the subpixel, and FIG. 13B is a cross-sectional view of the main part showing the cross-sectional structure taken along the line HH ′ in FIG. FIG. 4 is a cross-sectional view of the main part showing the structure of the reflecting portion 31. Moreover, the cross-sectional structure along the FF ′ connection line in the transmission part 30 corresponds to FIG.
In the modification of FIG. 13, a strip-shaped counter electrode (CT) and a strip-shaped reflective electrode (RAL) electrically connected to the strip-shaped counter electrode (CT) are formed on the glass substrate (SUB1) side. A comb-shaped pixel electrode (PIX) is formed on the interlayer insulating film 11 having a thickness t that covers the reflective electrode (RAL), and further, a comb-shaped second counter electrode (CT2) is formed. The pattern is such that each comb electrode of the electrode (PIX) is positioned between the comb electrodes of the second counter electrode (CT2). Here, one or more comb-tooth electrodes of the pixel electrode (PIX) are formed, and two or more comb-tooth electrodes of the second counter electrode (CT2) are formed.
The pixel electrode (PIX) of the reflection unit 31 and the pixel electrode (PIX) of the transmission unit 30 are electrically connected to each other and are electrically connected to a source electrode of a thin film transistor (TFT) (not shown).

The reflective electrode (RAL) of the subpixel of interest is electrically connected to the comb-shaped counter electrode (CT1) in the transmissive portion 30 of the upper adjacent subpixel (not shown in FIG. 13A). The comb-shaped counter electrode (CT1) in the transmission part 30 of the subpixel of interest is electrically connected to the reflective electrode (RAL) of the adjacent subpixel not shown in FIG. It is connected to the.
Further, the second counter electrode (CT2) in the reflecting portion 31 is set to a potential substantially equal to that of the reflecting electrode (RAL). Alternatively, the second counter electrode (CT2) in the reflective portion 31 is adjacent to the reflective electrode (RAL) or the upper side not shown in FIG. 13A through a contact hole formed in the interlayer insulating film 11. It is desirable to electrically connect to the comb-shaped counter electrode (CT1) in the transmission part 30 of the subpixel.
Also in Modification 1 and Modification 2 of Example 2, as long as the transmissive part 30 has a cross-sectional structure as shown in FIG. 10A, the electric field applied to the liquid crystal layer (LC) of the reflective part 31 and the transmissive part 30 The retardation change of the liquid crystal layer (LC) can be made different between the reflective portion 31 and the transmissive portion 30.

In the second embodiment, the first modification, and the second modification, the reflective electrode (RAL) in one subpixel and the comb-shaped counter electrode (CT1) of the transmissive portion 30 are not electrically connected. As long as the transmissive part 30 has a pixel cross-sectional structure as shown in FIG. 10A, the reflective electrode (RAL) in one subpixel and the comb-shaped counter electrode (CT1) of the transmissive part 30 are operated. Even when applied to a normal transflective sub-pixel structure in which the two are electrically connected (that is, a transflective sub-pixel structure in which the transmissive part 30 and the reflective part 31 are both normally black), the same effect is obtained. Can be obtained.
Thereby, in the subpixel structure having the transmission part 30 and the reflection part 31 in one subpixel, the shape of the voltage-transmittance characteristic and the shape of the voltage-reflectance characteristic are brought close to each other, and the transmission part 30 and the reflection part 31 are simultaneously made. The unnaturalness of display can be eliminated under the actual usage conditions for viewing.
Therefore, the subpixel structure may be selected according to the design or manufacturing process restrictions of the liquid crystal display device.

In each of the above-described embodiments, the comb-shaped pixel electrode (PIX) may be a transparent conductive material or an opaque metal material.
In addition, a metal electrode is provided on at least a part of the upper layer or the lower layer of at least one of the counter electrode (CT, CT1, CT2) on the glass substrate (SUB2) side or the glass substrate (SUB1) side to provide the counter electrode (CT). And may be electrically connected. Thereby, the resistance of the counter electrodes (CT, CT1, CT2) can be reduced. This is particularly effective when the counter electrode (CT, CT1, CT2) is a transparent conductive material having a high resistivity such as ITO.
Further, a step is formed between the transmissive part 30 and the reflective part 31, and the thickness d ′ of the liquid crystal layer (LC) of the transmissive part 30 is made larger than the thickness d of the liquid crystal layer (LC) of the reflective part 31. It doesn't matter. In particular, a transparent liquid crystal layer thickness adjusting layer (a step forming layer (MR)) may be provided on the reflective substrate 31 on the glass substrate (SUB2) side. Thereby, the shape of the voltage-reflectance characteristic of the reflection part 31 and the shape of the voltage-transmittance characteristic of the transmission part 30 can be made closer.
An uneven shape may be imparted to the surface of the reflective electrode (RAL) by providing a film having an uneven surface under the strip-shaped reflective electrode (RAL). Thereby, a bright diffuse reflection display can be realized.

With respect to the arrangement of the optical member in FIG. 4, a second one having an absorption axis in the direction parallel to the alignment treatment direction of the alignment film (OR2) on the glass substrate (SUB2) side on the display surface side of the glass substrate (SUB2). A polarizing plate (POL2) is arranged, and on the side opposite to the glass substrate (SUB2) side of the glass substrate (SUB1), the alignment treatment direction of the alignment film (OR1) on the glass substrate (SUB1) side and the second polarizing plate (POL2). ) Of the first polarizing plate (POL1) having an absorption axis in a direction orthogonal to the absorption axis direction.
Further, a retardation plate may be disposed between the glass substrate (SUB2) and the second polarizing plate (POL2) or between the glass substrate (SUB1) and the first polarizing plate (POL1). Alternatively, a coating-type retardation plate may be formed between the glass substrate (SUB1) and the liquid crystal layer (LC), or between the glass substrate (SUB2) and the liquid crystal layer (LC).
On the glass substrate (SUB2) side, a color filter (FIR) or a black matrix (BM) may be disposed on the surface facing the glass substrate (SUB1). As a result, color display is realized, and unnecessary liquid crystal operation areas can be shielded from light. The interlayer insulating film 11 may be composed of a plurality of layers made of different materials.
You may provide the support | pillar for keeping the thickness of a liquid-crystal layer (LC) constant in the part corresponding to a black matrix (BM). Moreover, this support | pillar may be provided in the glass substrate (SUB1) side. Note that in the case where a black matrix (BM) is not provided, a support is provided between adjacent subpixels.

The thickness of the liquid crystal layer (LC) of the reflective portion 31 is set to about ½ of the transmissive portion 30 by the liquid crystal layer thickness adjusting layer (step forming layer (MR)) and the support.
Since the end portion of the liquid crystal layer thickness adjusting layer (the step forming layer (MR)) is always formed at the boundary portion between the reflection portion 31 and the transmission portion 30, the black on the glass substrate (SUB2) side is covered so as to cover this boundary portion. A matrix (BM) may be arranged. Thereby, it is possible to block light leakage due to the disorder of the liquid crystal alignment generated at the end of the liquid crystal layer thickness adjusting layer (step forming layer (MR)), and to maintain a high contrast ratio.
The retardation of the liquid crystal layer (LC) is set to be about λ / 4 or more when no electric field is applied. For example, when the birefringence of the liquid crystal material is about 0.069 in addition to the settings in Tables 1 and 3, the thickness of the liquid crystal layer (LC) of the reflection unit 31 is about 2 μm, and the liquid crystal layer (LC of the transmission unit 30 is LC ) May be about 4 μm. Conversely, the retardation of the liquid crystal layer (LC) may be set to about λ / 4 when an electric field is applied.
Further, a guest-host mode may be used as the display mode. As the alignment state of the liquid crystal, horizontal alignment, twist alignment, vertical alignment, hybrid alignment, or the like can be used.
The color filter (FIR) of the reflection unit 31 may be partially removed for each color. Furthermore, as a whole liquid crystal display device, a backlight is provided on the side opposite to the display surface of the first polarizing plate (POL1).
As mentioned above, the invention made by the present inventor has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

It is a top view which shows the electrode structure of the sub pixel of the transflective liquid crystal display device of Example 1 of this invention. FIG. 2 is a cross-sectional view of a main part showing a cross-sectional structure along an A-A ′ connection line in FIG. 1 and a B-B ′ connection line in FIG. 1. It is principal part sectional drawing which shows the subpixel structure of the transflective liquid crystal display device of the comparative example in the transflective liquid crystal display device of Example 1 of this invention. It is a figure which shows arrangement | positioning of the optical member in the transflective liquid crystal display device of Example 1 of this invention, and the transflective liquid crystal display device of a comparative example. It is a figure which shows the voltage (V) -reflectance (RF) characteristic obtained by calculation in the transflective liquid crystal display device of Example 1 of this invention and the transflective liquid crystal display device of a comparative example. It is a figure which shows the drive voltage which gives the maximum contrast ratio in the transflective liquid crystal display device of Example 1 of this invention, and the transflective liquid crystal display device of a comparative example, and a maximum contrast ratio. It is a figure which shows the voltage (V) -transmittance (TF) characteristic obtained by calculation in the transflective liquid crystal display device of Example 1 of this invention. It is a figure for demonstrating the sub pixel of the modification of the transflective liquid crystal display device of Example 1 of this invention. It is a top view which shows the electrode structure of the sub pixel of the transflective liquid crystal display device of Example 2 of this invention. FIG. 10 is a main part sectional view showing a sectional structure taken along the F-F ′ connecting line in FIG. 9 and the G-G ′ connecting line in FIG. 9; It is principal part sectional drawing which shows the equivalent electrode structure of the transmission part of a subpixel in the transflective liquid crystal display device of Example 2 of this invention. It is a top view which shows the electrode structure of the sub pixel of the modification 1 of the transflective liquid crystal display device of Example 2 of this invention. It is a figure for demonstrating the electrode structure of the sub pixel of the modification 2 of the transflective liquid crystal display device of Example 2 of this invention. It is a top view which shows the electrode structure of the sub pixel of the transflective liquid crystal display device used as the premise of this invention. It is principal part sectional drawing which shows the cross-section along the A-A 'connection line of FIG. It is principal part sectional drawing which shows the cross-sectional structure along the B-B 'connection line of FIG. It is principal part sectional drawing which shows the cross-section along the C-C 'connection line of FIG. In the transflective liquid crystal display device which is the premise of the present invention, FIG.

Explanation of symbols

11, 11h, 12A to 12D, 13 Interlayer insulating film 11a Interlayer insulating film intermediate surface 15 Insulating film 30 Transmission portion 31 Reflection portion 51 Pixel electrode of transmission portion 52 Pixel electrode of reflection portion 53 Connection portion 1SPIX 1 subpixel region PIX pixel electrode LC liquid crystal layer SUB1, SUB2 glass substrate BM black matrix FIR color filter layer MR step forming layer OR1, OR2 alignment film POL1, POL2 polarizing plate CT, CT1, CT2, CTI counter electrode RAL reflective electrode D video line (drain line or source line) )

Claims (22)

A liquid crystal display panel having a pair of substrates and a liquid crystal sandwiched between the pair of substrates;
The liquid crystal display panel has a plurality of subpixels each having a transmission part and a reflection part,
Each subpixel of the plurality of subpixels includes a pixel electrode formed on one of the pair of substrates and a first counter electrode formed on the one substrate,
A transflective liquid crystal display device that drives the liquid crystal by generating an electric field with the pixel electrode and the first counter electrode,
A transflective liquid crystal display device, wherein a second counter electrode is formed only in a region of the other substrate facing the reflective portion of each subpixel of the other substrate. The first counter electrode of the reflective portion is a strip-shaped electrode,
An interlayer insulating film formed on the strip-shaped first counter electrode of the reflective portion;
The transflective liquid crystal display device according to claim 1, wherein the pixel electrode of the reflective portion is formed on the interlayer insulating film. The pixel electrode and the second counter electrode of the reflective portion are comb-like electrodes,
When the comb-like electrode of the pixel electrode of the reflective portion and the comb-like electrode of the second counter electrode are projected onto the one substrate from a direction orthogonal to the main surface of the liquid crystal display panel. 3. The transflective liquid crystal according to claim 1, wherein each comb electrode of the pixel electrode of the reflecting portion is located between each comb electrode of the second counter electrode. 4. Display device.   4. The transflective type according to claim 1, wherein the pixel electrode of the transmissive portion and the first counter electrode of the transmissive portion are comb-like electrodes. 5. Liquid crystal display device. The comb-like electrode of the pixel electrode of the transmissive part and the comb-like electrode of the first counter electrode of the transmissive part are formed on the same insulating film,
5. The transflective liquid crystal display according to claim 4, wherein each comb electrode of the pixel electrode of the transmissive portion is positioned between each comb electrode of the first counter electrode of the transmissive portion. 6. apparatus. The first counter electrode of the transmission part is a band-shaped electrode,
An interlayer insulating film formed on the strip-shaped first counter electrode of the transmissive portion;
4. The transflective liquid crystal display device according to claim 1, wherein the pixel electrode of the transmissive portion is formed on the interlayer insulating film. 5.   The transflective liquid crystal display device according to claim 6, wherein the pixel electrode of the transmissive portion is a comb-like electrode. A liquid crystal display panel having a pair of substrates and a liquid crystal sandwiched between the pair of substrates;
The liquid crystal display panel has a plurality of subpixels each having a transmission part and a reflection part,
Each subpixel of the plurality of subpixels includes a pixel electrode formed on one of the pair of substrates and a first counter electrode formed on the one substrate,
A transflective liquid crystal display device that drives the liquid crystal by generating an electric field with the pixel electrode and the first counter electrode,
The pixel electrode of the transmissive part and the first counter electrode of the transmissive part are comb-like electrodes,
An interlayer insulating film formed on the first counter electrode of the transmissive portion;
The pixel electrode of the transmissive part is formed on the interlayer insulating film,
When the pixel electrode of the transmissive part and the first counter electrode of the transmissive part are projected onto the one substrate from a direction orthogonal to the main surface of the liquid crystal display panel, the pixel electrode of the transmissive part A transflective liquid crystal display device characterized in that at least a part of each of the comb-teeth electrodes and each comb-teeth electrode of the first counter electrode of the transmissive portion overlap each other.   9. The transflective liquid crystal display device according to claim 8, wherein a second counter electrode is formed in a region of the pair of substrates facing the reflecting portion of each subpixel of the other substrate. . The first counter electrode of the reflective portion is a strip-shaped electrode,
An interlayer insulating film formed on the strip-shaped first counter electrode of the reflective portion;
The transflective liquid crystal display device according to claim 8, wherein the pixel electrode of the reflective portion is formed on the interlayer insulating film.   The transflective liquid crystal display device according to claim 10, wherein the pixel electrode of the reflective portion is a comb-like electrode. The pixel electrode and the second counter electrode of the reflective portion are comb-like electrodes,
When the comb-like electrode of the pixel electrode of the reflective portion and the comb-like electrode of the second counter electrode are projected onto the one substrate from a direction orthogonal to the main surface of the liquid crystal display panel. 12. The comb-shaped electrode of the pixel electrode of the reflective portion is located between the comb-shaped electrodes of the second counter electrode. 12. Transflective liquid crystal display device. The pixel electrode of the reflective portion is a comb-like electrode,
The first counter electrode of the reflective portion is a strip-shaped electrode,
An interlayer insulating film formed on the strip-shaped first counter electrode of the reflective portion;
The comb-like electrode of the pixel electrode of the reflective portion is formed on the interlayer insulating film,
A second counter electrode formed in the region of the reflective portion on the interlayer insulating film;
The second counter electrode of the reflecting portion is a comb-like electrode,
9. The transflective liquid crystal display according to claim 8, wherein each comb-tooth electrode of the pixel electrode of the reflection portion is positioned between each comb-tooth electrode of the second counter electrode of the reflection portion. apparatus.   When the two comb-tooth electrodes of the second counter electrode, in which the comb-shaped electrode of the pixel electrode of the reflective portion is positioned between one comb-tooth electrode and the other comb-tooth electrode, An interval between the comb electrode of the pixel electrode and the one comb electrode of the second counter electrode; and the comb electrode of the pixel electrode and the second counter electrode of the reflective portion. 14. The transflective liquid crystal display device according to claim 3, 12, or 13, wherein the distance between the other comb-teeth electrode is the same.   The transflective type according to claim 14, wherein each of the comb electrodes of the second counter electrode and each of the comb electrodes of the pixel electrode of the reflecting portion have the same electrode width. Liquid crystal display device.   The comb-tooth electrode of the second counter electrode is also formed at a boundary between the adjacent sub-pixels, according to claim 3, 12, 13, 14, or 15. The transflective liquid crystal display device described. The pixel electrode of the transmissive part and the pixel electrode of the reflective part are both comb-like electrodes,
The interval between the comb electrodes of the pixel electrode of the reflection portion is wider than the interval of the comb electrodes of the pixel electrode of the transmission portion. The transflective liquid crystal display device described in 1.   18. The half according to claim 1, wherein the same driving voltage is applied to the first counter electrode and the second counter electrode of the reflecting portion. Transmission type liquid crystal display device.   In each of the sub-pixels, the pixel electrode is common to the transmissive part and the reflective part, and the first counter electrode is independent from the transmissive part and the reflective part. The transflective liquid crystal display device according to any one of claims 1 to 18.   In each subpixel, the potential applied to the first counter electrode of one of the transmissive portion or the reflective portion is higher than the potential applied to the pixel electrode, and the transmissive portion or the 20. The transflective liquid crystal display device according to claim 19, wherein the potential applied to the other first counter electrode of the reflective portion is lower than the potential applied to the pixel electrode. . When two adjacent display lines are one display line and the other display line, the first counter electrode of the transmissive portion of each subpixel of the one display line and the one display line Different reference voltages are applied to the first counter electrode of the reflective portion of each subpixel,
The same reference is used for the first counter electrode of the reflective portion of each subpixel of the one display line and the first counter electrode of the transmissive portion of each subpixel of the other display line. The transflective liquid crystal display device according to any one of claims 1 to 20, wherein a voltage is applied.   The first counter electrode of the reflective portion in each subpixel of the one display line and the first counter electrode of the transmissive portion in each subpixel of the other display line are common electrodes. The transflective liquid crystal display device according to claim 21, wherein the transflective liquid crystal display device is provided.

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