JP5401057B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device using a vertical alignment (VA) mode.

  Liquid crystal display devices are utilized in various fields as display devices for OA equipment such as personal computers and televisions, taking advantage of features such as light weight, thinness, and low power consumption. In recent years, liquid crystal display devices are also used as mobile terminal devices such as mobile phones, display devices such as car navigation devices and game machines.

  Such a liquid crystal display device is required to improve display quality such as an increase in viewing angle and an improvement in contrast ratio. In a multi-domain vertical alignment (MVA) mode liquid crystal display device having a plurality of domains having different alignment directions in one pixel, the viewing angle is compensated for by the plurality of domains, and vertical alignment processing is adopted. As a result, the liquid crystal molecules in the vicinity of the alignment film surface are aligned substantially perpendicularly to the main surface of the substrate, and the birefringence of the liquid crystal layer becomes almost zero. It has the following characteristics.

  As such an MVA mode liquid crystal display device, a method of providing a convex structure to form an oblique electric field for controlling the alignment direction of liquid crystal molecules, a method of forming a slit (notch) in an electrode, etc. There is. When an insulating structure is applied, a separate process is often required, which may increase manufacturing costs.

  On the other hand, when applying a slit, when the protective film which protects the surface of the polarizing plate arrange | positioned at the counter substrate side is peeled, or when a surface discharge test is done, the surface of a polarizing plate may be charged. Due to such charging, an undesired electric field is applied to the liquid crystal layer from the slit of the counter electrode, and the liquid crystal molecules cannot form a desired alignment state.

  For example, in the normally black mode, black is displayed in a state where an electric field is not applied to the liquid crystal layer. However, when an undesired electric field is applied to the liquid crystal layer, the alignment state of the liquid crystal molecules changes, and light leakage does not occur. It will occur. As a result, the contrast ratio is reduced, or the display is visually recognized as display unevenness (visible white when displaying black), so that improvement in display quality is required.

For example, according to Patent Document 1, an optical film imparted with antistatic properties has been proposed as a countermeasure against static electricity generated when a protective film is peeled off. In particular, an antistatic pressure-sensitive adhesive optical film is proposed in which an antistatic layer is laminated on at least one surface of an optical film, and an adhesive layer is further laminated on the antistatic layer.
JP 2006-119348 A

  In an MVA mode liquid crystal display device, particularly a transflective liquid crystal display device in which each pixel has a reflective portion and a transmissive portion, there is an increasing demand for cost reduction, and in both reflective display and transmissive display, Improvement of display quality is desired.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a liquid crystal display capable of reducing costs and displaying an image with good display quality while having a wide viewing angle characteristic. To provide an apparatus.

A liquid crystal display device according to an aspect of the present invention includes:
In a liquid crystal display device having a reflective portion and a transmissive portion in each of a plurality of pixels arranged in a matrix,
Between the array substrate and the counter substrate, an array substrate having a pixel electrode in the reflective portion and the transmissive portion of each pixel, a counter substrate having a common counter electrode arranged opposite to the array substrate and common to a plurality of pixels And a liquid crystal layer containing liquid crystal molecules that are aligned substantially perpendicular to the main surface of the substrate when no electric field is formed between the pixel electrode and the counter electrode, and a liquid crystal display panel comprising:
An optical element disposed on each outer surface of the liquid crystal display panel, each including a polarizing plate, and a retardation plate disposed between the polarizing plate and the liquid crystal display panel;
With
The counter electrode is formed with a slit facing the pixel electrode,
Among the optical elements, at least the optical element disposed on the counter substrate side further adheres the polarizing plate and the retardation plate and has a diffusive first adhesive layer, and the retardation plate. A second adhesive layer that adheres to the liquid crystal display panel and has conductivity is provided.

  According to the present invention, it is possible to provide a liquid crystal display device that can reduce the cost and display an image with a good display quality while having a wide viewing angle characteristic.

  That is, since the counter electrode has a slit facing the pixel electrode, an inclined electric field is formed between the pixel electrode and the counter electrode in the vicinity of the slit. The liquid crystal molecules that are aligned substantially perpendicular to the main surface of the substrate in the state where no electric field is formed are inclined with respect to the main surface of the substrate by the inclined electric field, and are aligned in different directions across the slit. As a result, viewing angle compensation is possible, and a wide viewing angle characteristic can be obtained.

  In addition, since the slit formed in the counter electrode is applied to control the alignment of the liquid crystal molecules, a process for forming the structure is not necessary and cost can be reduced as compared with the case where the structure is separately applied. It becomes possible.

  Further, the optical element disposed on the counter substrate side includes a first adhesive layer having a diffusibility for adhering the polarizing plate and the phase difference plate, and also has a conductive property for adhering the phase difference plate and the liquid crystal display panel. A second adhesive layer having For this reason, the first adhesive layer can suppress display unevenness during reflective display, and can display an image with good display quality.

  Moreover, even if the surface of the polarizing plate is charged, it is shielded by the second adhesive layer, so that it is possible to suppress application of an undesired electric field to the liquid crystal layer through the slit of the counter electrode. For this reason, it is possible to suppress light loss during black display, and it is possible to display an image with good display quality.

  A liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings. Here, as a liquid crystal display device, a reflection unit that displays an image by selectively reflecting external light within one pixel and a transmission unit that displays an image by selectively transmitting backlight light are provided. An example of a transflective liquid crystal display device will be described.

  As shown in FIGS. 1 and 2, the liquid crystal display device is an active matrix type liquid crystal display device and includes a transflective liquid crystal display panel LPN. The liquid crystal display panel LPN includes a pair of substrates, that is, an array substrate (first substrate) AR and a counter substrate (second substrate) CT. The liquid crystal display panel LPN includes a liquid crystal layer LQ held between the array substrate AR and the counter substrate CT.

  Such a liquid crystal display panel LPN includes a display area (active area) DSP for displaying an image. The display area DSP is composed of a plurality of pixels PX arranged in an mxn matrix. Each pixel PX includes a reflection part PR and a transmission part PT.

  In addition, the liquid crystal display device includes a first optical element OD1 provided on one outer surface of the liquid crystal display panel LPN (that is, a surface opposite to the surface in contact with the liquid crystal layer LQ of the array substrate AR), and the liquid crystal A second optical element OD2 provided on the other outer surface of the display panel LPN (that is, the surface opposite to the surface in contact with the liquid crystal layer LQ of the counter substrate CT) is provided.

  Further, the liquid crystal display device includes a backlight unit BL that illuminates the liquid crystal display panel LPN from the first optical element OD1 side.

  The array substrate AR is formed using an insulating substrate 11 having optical transparency such as glass. That is, the array substrate AR is arranged on one main surface of the insulating substrate 11 (that is, the surface facing the liquid crystal layer LQ) in the display area DSP so as to extend along the row direction of each pixel PX. N scanning lines Y (Y1 to Yn), m signal lines X (X1 to Xm) arranged so as to extend along the column direction of each pixel PX, and scanning lines in each pixel PX Similarly to the scanning line Y, mxn switching elements 12 arranged in a region including the intersection of Y and the signal line X, mxn pixel electrodes 13 arranged in each pixel PX, in the row direction. Auxiliary capacitance lines AY, etc., which are respectively arranged so as to extend along the liquid crystal capacitance CLC and which are capacitively coupled to the pixel electrode 13 so as to constitute the auxiliary capacitance CS are provided.

  The scanning line Y and the auxiliary capacitance line AY are arranged substantially in parallel on the insulating substrate 11 and can be formed of the same material. The auxiliary capacitance line AY is disposed so as to face the pixel electrode 13 through an insulating film such as the gate insulating film 15 and to cross the plurality of pixel electrodes 13. The signal line X is disposed so as to be substantially orthogonal to the scanning line Y and the auxiliary capacitance line AY via an insulating film such as the gate insulating film 15. These signal lines X, scanning lines Y, and auxiliary capacitance lines AY are made of a conductive material such as aluminum, molybdenum, tungsten, or titanium.

  Each switching element 12 is configured by, for example, an n-channel thin film transistor. The switching element 12 includes a semiconductor layer 12SC. The semiconductor layer 12SC can be formed of, for example, polysilicon or amorphous silicon, and is formed of amorphous silicon here.

  The gate electrode 12G of the switching element 12 is connected to the scanning line Y (or formed integrally with the scanning line Y), and is disposed on the insulating substrate 11 together with the scanning line Y and the auxiliary capacitance line AY. The gate electrode 12G, the scanning line Y, and the auxiliary capacitance line AY are formed of, for example, molybdenum-tungsten (MoW) and covered with the gate insulating film 15. The gate insulating film 15 is made of an inorganic material such as a silicon oxide film and a silicon nitride film, for example. The semiconductor layer 12SC is disposed on the gate insulating film 15 so that a part thereof faces the gate electrode 12G, and the channel region is covered with the protective film 16.

  The source electrode 12S and the drain electrode 12D of the switching element 12 are disposed on both sides of the gate electrode 12G. That is, the source electrode 12S is in contact with the semiconductor layer 12SC through the low resistance film 17. The source electrode 12S is connected to the signal line X (or the source electrode 12S is formed integrally with the signal line X). The drain electrode 12D is in contact with the semiconductor layer 12SC through the low resistance film 18.

  The source electrode 12S and the drain electrode 12D can be formed of the same material as that of the signal line X. For example, the source electrode 12S and the drain electrode 12D are formed of a stacked body in which molybdenum (Mo) / aluminum (Al) / molybdenum (Mo) are sequentially stacked. . The source electrode 12S, the drain electrode 12D, and the signal line X are covered with an interlayer insulating film 19. The interlayer insulating film 19 is made of an inorganic material such as a silicon nitride film, for example.

  Further, the interlayer insulating film 19 is covered with an organic insulating film 14 formed of an organic material. On the surface of the organic insulating film 14, a concavo-convex pattern 14 </ b> P is formed in the reflective portion PR for the purpose of improving display quality in reflective display.

  The pixel electrode 13 includes a reflective electrode 13R disposed in the reflective portion PR and a transmissive electrode 13T disposed in the transmissive portion PT. In each pixel PX, the reflective electrode 13R and the transmissive electrode 13T are electrically connected. Such a pixel electrode 13 is disposed on the organic insulating film 14.

  The reflective electrode 13R covers the surface of the concavo-convex pattern 14P of the organic insulating film 14. The reflective electrode 13R is made of a light reflective conductive material such as aluminum. The transmissive electrode 13T covers the substantially flat surface of the organic insulating film 14. The transmissive electrode 13T is formed of a light-transmitting conductive material such as indium tin oxide (ITO) or IZO (indium zinc oxide).

  Such a pixel electrode 13 is electrically connected to the switching element 12. Here, the switching element 12 is disposed, for example, in the reflection part PR, and an interlayer insulating film 19 and an organic insulating film 14 are interposed as insulating layers between the pixel electrode 13 and the reflecting electrode 13R. . The reflective electrode 13 </ b> R is in contact with the drain electrode 12 </ b> D of the switching element 12 through a contact hole CH formed in the organic insulating film 14 and the interlayer insulating film 19.

  The surface in contact with the liquid crystal layer LQ of the array substrate AR is covered with the first alignment film AL1.

  On the other hand, the counter substrate CT is formed using an insulating substrate 21 having optical transparency such as glass. That is, the counter substrate CT includes a counter electrode 22, a resin layer 23, and the like on one main surface of the insulating substrate 21 (that is, a surface facing the liquid crystal layer LQ) in the display area DSP.

  The counter electrode 22 is arranged to cover the resin layer 23 and to face the pixel electrodes 13 corresponding to the plurality of pixels PX. The counter electrode 22 is formed of a light-transmitting conductive material such as ITO, like the transmissive electrode 13T.

  The resin layer 23 forms a gap difference between the liquid crystal layer LQ in the reflection part PR and the transmission part PT. That is, in the transflective liquid crystal display panel LPN, the gap between the array substrate AR and the counter substrate CT is formed to be different between the reflective portion PR and the transmissive portion PT. The reflection part PR and the transmission part PT are formed in appropriate gaps so that the substantial optical path lengths are substantially equal. In many cases, the gap in the reflection part PR is set to approximately half of the transmission part PT.

  Such a gap difference is formed by the resin layer 23. The resin layer 23 is disposed mainly corresponding to the reflection part PR. For this reason, a gap difference substantially corresponding to the thickness of the resin layer 23 is formed between the reflection part PR and the transmission part PT. For example, the resin layer 23 is formed of a resin material having optical transparency.

  In the color display type liquid crystal display device, the counter substrate CT includes a color filter layer 24 disposed on one main surface of the insulating substrate 21 corresponding to each pixel PX. The color filter layer 24 is formed of colored resins that are colored in a plurality of different colors, for example, three primary colors such as red, blue, and green. The red colored resin, the blue colored resin, and the green colored resin are disposed corresponding to the red pixel, the blue pixel, and the green pixel, respectively.

  In the example of the color display type liquid crystal display device shown in FIG. 2, the color filter layer 24 is disposed on the counter substrate CT side, but may be disposed on the array substrate AR side. In this case, the organic insulating film 14 in the array substrate AR can be replaced with the color filter layer 24. Further, the counter substrate CT may include an overcoat layer on the color filter layer 24 in order to alleviate the influence of unevenness on the surface of the color filter layer 24.

  The surface of the counter substrate CT that contacts the liquid crystal layer LQ is covered with the second alignment film AL2.

  When such a counter substrate CT and the array substrate AR as described above are disposed so that the first alignment film AL1 and the second alignment film AL2 face each other, a spacer (not shown) disposed between the counter substrate CT and the array substrate AR is disposed. For example, a predetermined gap is formed by a columnar spacer formed integrally with one substrate by a resin material. The array substrate AR and the counter substrate CT are bonded together with a sealing material in a state where a predetermined gap is formed.

  The liquid crystal layer LQ is composed of a liquid crystal composition including liquid crystal molecules 40 enclosed in a gap formed between the first alignment film AL1 of the array substrate AR and the second alignment film AL2 of the counter substrate CT. Yes. The liquid crystal molecules 40 have, for example, negative dielectric anisotropy.

  The first alignment film AL1 and the second alignment film AL2 are in a state where no potential difference is formed between the pixel electrode 13 and the counter electrode 22, that is, an electric field is formed between the pixel electrode 13 and the counter electrode 22. When there is no electric field, the liquid crystal molecules 40 are aligned substantially perpendicularly to the main surface of the insulating substrate 11 (or array substrate AR) and the main surface of the insulating substrate 21 (or counter substrate CT). Yes. A material for forming the first alignment film AL1 and the second alignment film AL2 is not particularly limited as long as it is a light-transmitting thin film that basically exhibits vertical alignment.

  The liquid crystal display device also includes at least a part of the scanning line driver YD connected to the n scanning lines Y and at least a part of the signal line driver XD connected to the m signal lines X. It has. In particular, when a configuration in which the switching element 12 includes a semiconductor layer 12SC made of polysilicon is applied, at least a part of the scanning line driver YD and the signal line driver XD can be integrally formed on the array substrate AR, and switching is performed. Similar to the element 12, a thin film transistor including a polysilicon semiconductor layer can be included.

  The scanning line driver YD sequentially supplies scanning signals (driving signals) to the n scanning lines Y based on control by the controller CNT. Further, the signal line driver XD supplies video signals (drive signals) to the m signal lines X at a timing when the switching elements 12 of each row are turned on by the scanning signal based on the control by the controller CNT. Thereby, the pixel electrode 13 of each row is set to a pixel potential corresponding to the video signal supplied via the corresponding switching element 12.

  For the transflective liquid crystal display panel LPN as described above, reflection display and transmission display are performed using circularly polarized light or elliptically polarized light. For this reason, the first optical element OD1 and the second optical element OD2 include at least a polarizing plate and a retardation plate, and are configured as a circularly polarizing element or an elliptically polarizing element.

  More specifically, as shown in FIG. 3, the first optical element OD1 includes a first polarizing plate PL1, a retardation plate RF disposed between the first polarizing plate PL1 and the liquid crystal display panel LPN, It is configured with. The second optical element OD2 includes a second polarizing plate PL2, and a retardation plate RF disposed between the second polarizing plate PL2 and the liquid crystal display panel LPN.

  The first polarizing plate PL1 and the second polarizing plate PL2 applied here have an absorption axis and a transmission axis orthogonal to each other in a plane orthogonal to the light traveling direction. Such a polarizing plate extracts light having a vibrating surface in one direction parallel to the transmission axis, that is, light having a linearly polarized light state, from light having a vibrating surface in a random direction.

  The phase difference plate RF included in the first optical element OD1 and the second optical element OD2 has refractive index anisotropy, and each has a slow axis and a fast axis that are orthogonal to each other in the plane. . For this reason, the phase difference plate RF has a predetermined retardation (phase difference) defined by Δn · d (nm) (where Δn = ne−no, d is the thickness of the phase difference plate). Here, when the retardation film RF has a predetermined retardation (that is, a wavelength of light transmitted through λ) between light of a predetermined wavelength (for example, 550 nm) that transmits the slow axis and the fast axis, respectively, λ / 4 phase difference).

  In the first optical element OD1, the first polarizing plate PL1 and the retardation plate RF are bonded to each other by the first adhesive layer AD11. Further, the array substrate AR of the liquid crystal display panel LPN, in particular, the insulating substrate 11 and the phase difference plate RF are bonded to each other by the second adhesive layer AD12.

  In the second optical element OD2, the second polarizing plate PL2 and the retardation plate RF are bonded to each other by the first adhesive layer AD21. Further, the counter substrate CT of the liquid crystal display panel LPN, in particular, the insulating substrate 21 and the retardation film RF are bonded to each other by the second adhesive layer AD22.

  In this embodiment, the liquid crystal molecules 40 included in the liquid crystal layer LQ have their major axes substantially perpendicular to the main surface of the substrate by the alignment control by the first alignment film AL1 and the second alignment film AL2 when there is no electric field. It is aligned substantially parallel to the direction (or the normal direction of the liquid crystal display panel LPN). In such a state, in the transmissive part PT, the backlight light transmitted through the first optical element OD1 is absorbed by the second optical element OD2 after passing through the liquid crystal layer LQ having a substantially zero retardation. Further, in the reflection part PR, the external light transmitted through the second optical element OD2 is reflected by the reflective electrode 13R after passing through the liquid crystal layer LQ having a substantially zero retardation, and again through the liquid crystal layer LQ. 2 absorbed by the optical element OD2. Therefore, the transmittance of the liquid crystal display panel LPN is the lowest (that is, a black screen is displayed).

  On the other hand, in a state where an electric field is formed between the pixel electrode 13 and the counter electrode 22, the liquid crystal molecules 40 having negative dielectric anisotropy are aligned in a direction substantially orthogonal to the electric field. With respect to the electric field inclined with respect to the normal line of the substrate main surface, the liquid crystal molecules 40 are aligned in the direction in which the major axis is substantially parallel to or inclined with respect to the substrate main surface. For this reason, the liquid crystal layer LQ has a predetermined retardation.

  In such a state, in the transmission part PT, the backlight light transmitted through the first optical element OD1 is provided with retardation when transmitted through the liquid crystal layer LQ, and at least a part of the backlight light can transmit through the second optical element OD2. It becomes. In the reflection part PR, the external light transmitted through the second optical element OD2 is reflected by the reflective electrode 13R after being provided with retardation when transmitted through the liquid crystal layer LQ, and retardation when transmitted through the liquid crystal layer LQ again. Is provided, and at least a part thereof can pass through the second optical element OD2. Therefore, a white screen is displayed.

  In this way, a normally black mode vertical alignment mode is realized.

  By the way, in this embodiment, a multi-domain structure capable of viewing angle compensation is configured. More specifically, the liquid crystal display device includes alignment control means for controlling the alignment of the liquid crystal molecules 40 in each pixel PX. In particular, in this embodiment, the orientation control means is constituted by a slit SL formed in the counter electrode 22 as shown in FIGS. The slit SL is opposed to the pixel electrode 13 of each pixel PX.

  In the first configuration example shown in FIG. 4, each pixel PX has transmission parts PT <b> 1 and PT <b> 2 on both sides along the direction parallel to the signal line X, that is, the column direction, with the reflection part PR interposed therebetween. In such a pixel configuration, for example, the slit SL extends along the direction parallel to the scanning line Y, that is, the row direction, through substantially the center of the reflection part PR.

  When an electric field is formed between the pixel electrode 13 and the counter electrode 22, an inclined electric field is formed in the vicinity of the slit SL. At this time, in the reflection part PR, the liquid crystal molecules 40 are aligned in different directions on both sides of the slit SL (for example, as indicated by arrows in the drawing, the liquid crystal molecules 40 are aligned toward the slit SL. ). Also in the transmissive portions PT1 and PT2, the liquid crystal molecules 40 are aligned in different directions (for example, as indicated by arrows in the figure, the liquid crystal molecules 40 in the transmissive portion PT1 and the liquid crystal molecules 40 in the transmissive portion PT2 are respectively Oriented toward the slit SL).

  Such a first configuration example is suitable for a VGA class device having a pixel pitch of 15 to 35 μm, for example.

  In the second configuration example illustrated in FIG. 5, each pixel PX includes a reflection part PR and a transmission part PT arranged in the column direction. In such a pixel configuration, for example, the slit SL extends along the row direction through substantially the center of the reflection part PR and the transmission part PT. In the example shown in FIG. 5, the slits SL are formed discontinuously in the pixel PX.

  Also in such a second configuration example, when an electric field is formed between the pixel electrode 13 and the counter electrode 22, an inclined electric field is formed in the vicinity of the slit SL. At this time, in the reflection part PR, the liquid crystal molecules 40 are aligned in different directions on both sides of the slit SL. In the transmissive part PT, the liquid crystal molecules 40 are aligned in different directions on both sides of the slit SL. For example, as indicated by the arrows in the figure, the liquid crystal molecules 40 are aligned toward the slit SL in the reflection part PR and the transmission part PT.

  Such a second configuration example is suitable for a device of QVGA class or higher with a pixel pitch of 35 to 100 μm, for example.

  That is, in these first configuration example and second configuration example, electric fields inclined in opposite directions with respect to the slit SL are formed in regions adjacent to each other with the slit SL interposed therebetween, so that the liquid crystal molecules 40 in the respective regions are also formed. Under the influence of such a gradient electric field, they are oriented in opposite directions. As a result, the viewing angle is compensated, and a wide viewing angle characteristic can be secured.

  As described above, by applying the slit SL as the orientation control means, a separate process for forming the structure is not required, and the number of manufacturing processes is reduced as compared with the case where a structure such as a protrusion is applied. In addition, the manufacturing cost can be reduced.

  In the first configuration example and the second configuration example, for example, in a device in which the diagonal dimension of the display area DSP is 1.5 to 5.0 type (1.6 to 4.8 type in an actual product), The area ratio of the slit SL formed in the electrode 22 is 7 to 20% (more preferably 8 to 15%) in the transmission part PT, and 20 to 60% (more preferably 30 to 50%) in the reflection part PR. is there.

  In particular, in this embodiment, of the first optical element OD1 and the second optical element OD2, at least in the second optical element OD2, the first adhesive layer that bonds the second polarizing plate PL2 and the phase difference plate RF. AD21 has diffusibility. In the second optical element OD2, the second adhesive layer AD22 that bonds the phase difference plate RF and the array substrate AR has conductivity.

  About the diffusibility of 1st contact bonding layer AD21, it is desirable that it is 20 to 50% of range in haze, and here 1st contact bonding layer AD21 of 45% haze was applied. The conductivity of the second adhesive layer AD22 is preferably in the range of 8 to 12Ω / □ in terms of surface resistance. Here, the second adhesive layer AD22 having a surface resistance value of 9 to 11Ω / □ is applied. .

  By applying the first adhesive layer AD21 as described above, display unevenness at the time of reflective display can be suppressed, and an image with good display quality can be displayed. That is, in the reflective part PR, the concave and convex portions are formed on the reflective surface by disposing the reflective electrode 13R so as to cover the concave and convex pattern 14P. This improves the appearance by diffusing the reflected light during reflection display, but when the uneven pattern is arranged on the flat part, many tapers of the same angle are distributed, so depending on the viewing angle Display interference such as rainbow unevenness is likely to occur due to interference of light.

  On the other hand, by applying the first adhesive layer AD21 having diffusibility in the second optical element OD2 on the counter substrate side, it becomes possible to improve the diffusibility of the reflected light and improve the display quality. Further, when the reflective electrode 13R is exposed through the slit SL, the reflective electrode 13R may become a mirror and cause reflection, but by applying the diffusive first adhesive layer AD21, the reflection is reflected. Is suppressed, and the display quality can be improved.

  Further, by applying the second adhesive layer AD22 as described above, even if the surface of the second polarizing plate PL2 on the counter substrate side is charged, an external electric field due to the influence of this charging is shielded by the second adhesive layer AD22. It becomes possible to do. That is, when the second adhesive layer AD22 is disposed near the second polarizing plate PL2, there is a possibility that strong charges may reach the liquid crystal layer LQ without being fully polarized.

  On the other hand, in this embodiment, the second adhesive layer AD22 is separated from the second polarizing plate PL2 and is disposed in the vicinity of the liquid crystal display panel LPN. For this reason, when the second polarizing plate PL2 is charged, it is relaxed before reaching the second adhesive layer AD22, and is polarized in the second adhesive layer AD22, thereby promoting the dispersion of electric charges. Thereby, in the configuration in which the slit SL is applied to the counter electrode 22 as the alignment control means, it is possible to suppress application of an undesired external electric field to the liquid crystal layer LQ through the slit SL of each pixel PX. For this reason, it is possible to suppress light loss during black display, and it is possible to display an image with good display quality.

  In this embodiment, it is desirable that the first adhesive layer AD21 in the second optical element OD2 has a higher adhesive force than the second adhesive layer AD22.

  That is, the first adhesive layer AD21 is disposed on the surface side of the second optical element OD2, and there are few members to support the second adhesive layer AD22. Here, the second polarizing plate PL2 and the retardation plate RF are bonded and supported. Have a role to play.

For this reason, it is desirable that the first adhesive layer AD21 has a relatively high adhesive force, and the reliability can be improved by firmly bonding the second polarizing plate PL2 and the retardation plate.

  On the other hand, the second adhesive layer AD22 is disposed at a position away from the surface of the second optical element OD2 for the reasons described above, and plays a role of adhering to the liquid crystal display panel LPN while supporting the entire second optical element OD2. . For this reason, when a defect occurs in the second optical element OD2, it is desirable that the second adhesive layer AD22 has a relatively low adhesive force in order to enable easy replacement. Therefore, at least the adhesive force of the second adhesive layer AD22 is weaker than the adhesive force of the first adhesive layer AD21, so that it can be easily reworked and the yield can be improved.

  In addition, when the adhesive force with respect to the same glass substrate was compared about 1st adhesive layer AD21 and 2nd adhesive layer AD22 applied here, 1st adhesive layer AD21 has higher adhesive force than 2nd adhesive layer AD22. It was confirmed.

  In this embodiment, the first optical element OD1 and the second optical element OD2 employ a configuration (thin polarizing plate) in which the polarizer constituting the polarizing plate is sandwiched between the base film and the first adhesive layer. May be.

  FIG. 6 illustrates a specific configuration of the second optical element OD2. The second polarizing plate PL2 includes a base film 101 and a polarizer 102 laminated on the base film 101. Yes. The base film 101 can be formed of triacetate cellulose (TAC). The polarizer 102 can be formed of uniaxially stretched polyvinyl alcohol (PVA). The polarizer 102 is bonded to the phase difference plate RF by the first adhesive layer AD21.

  In FIG. 6, the configuration of the second optical element OD2 is illustrated, but it is needless to say that the first polarizing plate PL1 having the same configuration can also be applied to the first optical element OD1. The polarizing plate usually employs a configuration in which a polarizer is sandwiched between a pair of base films. However, by applying the configuration shown in FIG. 6, the number of components constituting the optical element can be reduced. It is possible to reduce the thickness and cost.

  In the case of the polarizing plate having the above-described configuration, it tends to be relatively easily contracted. Therefore, if the adhesive layer that has been applied in the past is applied as it is, there may be a problem in terms of reliability due to insufficient adhesive force, but if the adhesive force is excessively high, rework becomes difficult, There is a risk of reducing the yield. For this reason, it is desirable to apply what optimized the adhesive force as demonstrated in this embodiment as a 1st contact bonding layer and a 2nd contact bonding layer.

Example 1
The first optical element OD1 and the second optical element OD2 are applied to the transflective liquid crystal display panel LPN having a multi-domain structure as shown in FIG. 3, and in particular, the liquid crystal display panel LPN and the phase difference plate As the second adhesive layer AD22 between the RF, a conductive layer was used. This is because the effect of preventing light leakage due to charging is increased by imparting conductivity to a portion as far as possible from the polarizing plate surface.

  In Example 1 as described above, for both the first configuration example shown in FIG. 4 and the second configuration example shown in FIG. 5, the effect of charging was confirmed when the protective film was peeled off and in the surface discharge test. When black display was performed in the absence of an electric field, it was confirmed that in any of the configuration examples, light leakage during transmissive display and reflective display was suppressed, and good display quality was obtained.

Example 2
The first optical element OD1 and the second optical element OD2 are applied to the transflective liquid crystal display panel LPN having a multi-domain structure as shown in FIG. 3, and in particular, the liquid crystal display panel LPN and the phase difference plate For the second adhesive layer AD22 between the RF, a conductive material is applied, and for the first adhesive layer AD21 between the second polarizing plate PL2 and the retardation film RF, a diffusive material is used. Applied. Here, a thin polarizing plate as shown in FIG. 6 was applied as the second polarizing plate PL2.

  In this configuration, when the thin polarizing plate is applied, if the diffusible first adhesive layer AD21 is disposed at the glass interface, the adhesive strength is insufficient and the reliability is NG, and if the adhesive strength is excessively increased, the reworkability is NG. Since the first adhesive layer AD21 is disposed between the second polarizing plate PL2 and the phase difference plate RF, the second adhesive layer AD22 having a large effect of preventing light leakage due to charging is made of glass. The configuration is arranged at the interface.

  In Example 2 as described above, for both the first configuration example shown in FIG. 4 and the second configuration example shown in FIG. 5, the effect of charging was confirmed when the protective film was peeled off and in the surface discharge test. When black display was performed in the absence of an electric field, light leakage during transmissive display and reflective display was suppressed in any configuration example, and reflection in the reflection part PR and display unevenness during reflective display were observed. It was confirmed that good display quality was obtained.

  As described above, according to the transflective liquid crystal display device of this embodiment, it is possible to reduce the cost and display an image with a good display quality while having a wide viewing angle characteristic.

  In addition, this invention is not limited to the said embodiment itself, In the stage of implementation, it can change and implement a component within the range which does not deviate from the summary. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

FIG. 1 is a diagram schematically showing a configuration of a transflective liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a structure of a liquid crystal display device including the transflective liquid crystal display panel shown in FIG. FIG. 3 is a diagram schematically showing a configuration of an optical element applicable to the liquid crystal display device shown in FIG. FIG. 4 is a plan view schematically showing a pixel configuration in a first configuration example in which slits are applied as orientation control means in the present embodiment. FIG. 5 is a plan view schematically showing a pixel configuration in a second configuration example in which slits are applied as orientation control means in the present embodiment. FIG. 6 is a diagram schematically showing the structure of a thin polarizing plate applicable to the optical element of this embodiment.

Explanation of symbols

LPN ... Liquid crystal display panel AR ... Array substrate CT ... Counter substrate LQ ... Liquid crystal layer 40 ... Liquid crystal molecule BL ... Backlight unit PX ... Pixel PR ... Reflector PT ... Transmitter Y ... Scanning line X ... Signal line AY ... Auxiliary capacitance line DESCRIPTION OF SYMBOLS 12 ... Switching element 13 ... Pixel electrode 13R ... Reflective electrode 13T ... Transmission electrode 22 ... Counter electrode SL ... Slit 23 ... Resin layer 24 ... Color filter layer OD1 ... 1st optical element PL1 ... 1st polarizing plate AD11 ... 1st adhesion layer AD12 ... second adhesive layer OD2 ... second optical element PL2 ... second polarizing plate AD21 ... first adhesive layer AD22 ... second adhesive layer RF ... phase difference plate 101 ... base film 102 ... polarizer

Claims (4)

In a liquid crystal display device having a reflective portion and a transmissive portion in each of a plurality of pixels arranged in a matrix,
Between the array substrate and the counter substrate, an array substrate having a pixel electrode in the reflective portion and the transmissive portion of each pixel, a counter substrate having a common counter electrode arranged opposite to the array substrate and common to a plurality of pixels And a liquid crystal layer containing liquid crystal molecules that are aligned substantially perpendicular to the main surface of the substrate when no electric field is formed between the pixel electrode and the counter electrode, and a liquid crystal display panel comprising:
An optical element disposed on each outer surface of the liquid crystal display panel, each including a polarizing plate, and a retardation plate disposed between the polarizing plate and the liquid crystal display panel;
With
The counter electrode is formed with a slit facing the pixel electrode,
Among the optical elements, at least the optical element disposed on the counter substrate side further adheres the polarizing plate and the retardation plate and has a diffusive first adhesive layer, and the retardation plate. A second adhesive layer that adheres to the counter substrate and is conductive and has a lower adhesive force than the first adhesive layer ;
The polarizing plate includes a base film and a polarizer laminated on the base film and bonded to the retardation plate by the first adhesive layer . Each pixel has a transmissive part on both sides along the column direction across the reflective part,
The liquid crystal display device according to claim 1, wherein the slit extends along a row direction through a substantially center of the reflecting portion. Each pixel has the reflection part and the transmission part arranged along the column direction,
2. The liquid crystal display device according to claim 1, wherein the slit extends along a column direction passing through substantially the center of the reflection portion and the transmission portion.   The liquid crystal display device according to claim 1, wherein the liquid crystal layer is composed of a liquid crystal composition having negative dielectric anisotropy.

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