KR100766634B1 - Liquid crystal display apparatus - Google Patents

Abstract

The liquid crystal display device includes a liquid crystal display panel and an optical unit. The liquid crystal display panel includes a first substrate, a second substrate, a plurality of pixel electrodes 18, and a plurality of projection units 32. Each pixel electrode 18 has a major axis of length 160 mu m or less. The value obtained by dividing the height of the projection portion 32 by the gap d between the first and second substrates is 0.14 to 0.6. The projection portion 32 has a width of 15 μm or less when measured in the first direction. The device satisfies the relation MIN (la, lb) / d <10.

Liquid crystal display device, liquid crystal display panel, optical unit, pixel electrode, projection unit, first substrate, second substrate

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY APPARATUS}

1 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is another cross-sectional view of the liquid crystal display shown in FIG.

3 is a plan view of the array substrate shown in FIGS. 1 and 2;

Fig. 4 is a plan view showing a pixel electrode and a projection portion of the liquid crystal display device according to the first embodiment when seen from the opposing substrate.

Fig. 5 is an enlarged plan view showing one of the pixel electrodes and one of the projections shown in Fig. 4;

Fig. 6 is a plan view showing a pixel electrode and a projection portion of a liquid crystal display device according to a fourth embodiment of the present invention as viewed from the opposing substrate.

Fig. 7 is an enlarged plan view showing one of the pixel electrodes and one of the projections shown in Fig. 6;

Fig. 8 shows how the aperture ratio and optical characteristics of the liquid crystal display device according to the first to fourth embodiments of the present invention change when the diagonal image size, pixel pitch, pixel size, and projection portion width change. table.

Fig. 9 is a plan view showing a pixel electrode and a projection portion of the liquid crystal display device according to the fifth embodiment of the present invention as viewed from the opposing substrate.

Fig. 10 is an enlarged plan view showing one of the pixel electrodes and one of the projections shown in Fig. 9;

Fig. 11 is a plan view showing a pixel electrode and a projection portion of the liquid crystal display device according to the sixth embodiment of the present invention as viewed from the opposing substrate.

FIG. 12 is an enlarged plan view showing one of the pixel electrodes and one of the projections shown in FIG.

FIG. 13 is a graph showing a relationship between a change in a reaction speed of a liquid crystal display according to an embodiment of the present invention and a shortest distance between one end of a corresponding pixel electrode measured in the first direction and one side of each projection portion; FIG. .

Fig. 14 is a plan view showing a pixel electrode and a projection portion of a liquid crystal display device according to a comparative example of an embodiment of the present invention as viewed from the opposite substrate.

Fig. 15 is an enlarged plan view showing one of the pixel electrodes and one of the projections shown in Fig. 14;

Fig. 16 is a table showing the aperture ratio and optical characteristics of the liquid crystal display according to the comparative example of the embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

1: liquid crystal display panel

2: optical unit

3: backlight unit

4: array substrate

5: counter substrate

6: liquid crystal layer

10: glass substrate

14 pixel unit

15: insulation layer

16: TFT

18: pixel electrode

32: projection unit

50: first optical unit

51: phase contrast plate

52: polarizing plate

60: second optical unit

The present invention relates to a liquid crystal display device.

In general, a liquid crystal display device has an array substrate, an opposing substrate having a gap maintained between the substrates and arranged on an opposite side of the array substrate, and a liquid crystal layer held between the array substrate and the opposing substrate. Liquid crystal display devices are light and thin and consume less electricity. Accordingly, liquid crystal displays are used in various devices such as office automation (OA) devices, information terminals, watches, and television receivers. When the liquid crystal display has a thin film transistor (TFT) used as a switching element, the liquid crystal display can respond to an input signal at high speed and display a high quality image. This is why liquid crystal displays are used as display units for use in various electronic devices that display large amounts of information such as portable TV receivers, computers, and the like.

In recent years, as a large amount of information is processed, there is an increasing demand for images to be displayed in high resolution and display speed to be increased. Image resolution is increased, for example, by reducing the size of the elements constituting the array substrate having the above-described TFT. In the vertical alignment mode, i.e., one display mode, the liquid crystal display responds to the input signal faster than in the conventional twisted nematic (TN) mode. In addition, in the vertical alignment mode, no rubbing processes need to be performed, leading to defects such as, for example, electrostatic damage.

In particular, the multi-domain vertical alignment (MVA) mode is actually widely used, since it can relatively easily increase the visual angle in this mode. In the MVA mode, a voltage is applied to each pixel having a projection to arrange liquid crystal molecules in various directions, thereby improving symmetry of visual characteristics and suppressing inversion. In another mode, a negative phase contrast plate is used to compensate for the visual dependence of the phase difference, which makes the liquid crystal layer appear black when the liquid crystal molecules stand vertically. Accordingly, the contrast time is changed to an appropriate value. In another mode, when the in-plane retardation is transmitted to the negative phase contrast plate, the plate is converted to a biaxial phase contrast plate to compensate for the visual dependence of the polarizer and obtain the desired CR visual characteristics.

Techniques for MVA are disclosed, for example, in US Pat. No. 6,724,452 B1. The aforementioned projection is arranged in a pixel. Local light divergence or voltage drop due to the step formed by this projection reduces the transmittance of the pixel. Therefore, the projection unit is a factor that degrades the image quality. If the space between any two adjacent pixel electrodes formed in the array substrate is large, the aperture ratio is reduced to inevitably reduce the transmittance. Therefore, in order to ensure high transmittance and high image contrast, it is desirable that the size of the projection and the space between the pixel electrodes be as small as possible. The size of the projection and the space between the pixel electrodes is determined by the balance between the optical properties and the alignment stability.

Recently, liquid crystal displays used in portable terminals are strongly required to display images of high contrast and high luminance. In addition, the liquid crystal display device is required to display an image at a high resolution of 300 ppi or more. The higher the resolution, the smaller the pixel electrode. The surface ratio of the projection to the pixel electrode is significantly increased when the MVA mode is used. Contrast ratio and transmittance inevitably fall considerably. Liquid crystal displays do not display images of sufficiently high quality. Therefore, coexistence of obtaining a high transmittance and a high contrast ratio and having a high sharpness suitable for a conventional balance relationship is required.

The present invention has been made in view of the above. SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device of high definition, which obtains high transmittance and high contrast ratio.

In order to achieve the above object, according to one aspect of the present invention,

A first substrate, a second substrate having a gap and arranged opposite to the first substrate, a liquid crystal layer made of a liquid crystal held between the first and second substrates and having a negative anisotropic dielectric constant, the first direction and A plurality of pixel electrodes each having a major axis arranged on the first substrate in the form of a matrix in a second direction perpendicular to the first direction and extending in the first direction, and provided on the second substrate and overlapping the pixel electrodes; A liquid crystal display panel comprising a plurality of projections spaced from the side of the pixel electrode and measured toward the first substrate and configured to control the direction in which the liquid crystal molecules are aligned when measured in the first direction;

A first optical unit provided outside the first substrate and configured to receive light and radiate the light as a circularly polarized light to the liquid crystal display panel; and a circular polarized light provided outside the second substrate and incident through the liquid crystal display panel. An optical unit comprising a second optical unit configured to emit light as linearly polarized light,

The major axis of each pixel electrode has a length of 160 μm or less,

The value obtained by dividing the height of the projection by the gap d between the first and second substrates is 0.14 to 0.6,

The projection has a width of 15 μm or less when measured in the first direction,

MIN (la, lb) / d <10, where la is the shortest distance between the pixel electrode position coordinates of the pixel electrodes and one of the projections overlapping the pixel electrode, lb is greater than the position coordinates and any other pixel electrode A liquid crystal display device is provided wherein the shortest distance between the ends of the pixel electrodes closer to the position coordinates, and MIN (la, lb) is the smaller of these distances la and lb.

According to another aspect of the invention,

A first substrate, a second substrate having a gap and arranged opposite to the first substrate, a liquid crystal layer made of a liquid crystal held between the first and second substrates and having a negative anisotropic dielectric constant, the first direction and A plurality of pixel electrodes each having a major axis arranged on the first substrate in the form of a matrix in a second direction perpendicular to the first direction and extending in the first direction, and provided on the second substrate and overlapping the pixel electrodes; A liquid crystal display panel comprising a plurality of projections spaced from the side of the pixel electrode when measured in the first direction and protruding toward the first substrate and having a height of 0.5 to 2 μm and configured to control the direction in which the liquid crystal molecules are aligned;

A first optical unit provided outside the first substrate and configured to receive light and radiate the light as a circularly polarized light to the liquid crystal display panel; and a circular polarized light provided outside the second substrate and incident through the liquid crystal display panel. An optical unit comprising a second optical unit configured to emit light as linearly polarized light,

The major axis of each pixel electrode has a length of 160 μm or less,

The first and second substrates are spaced apart by a gap d of 2 to 5 μm,

The projection has a width of 15 μm or less when measured in the first direction,

Projections are provided in the form of stripes extending in a second direction, each provided on a pixel electrode along a second direction, and arranged to divide the pixel electrode into two parts of substantially the same size along the first direction, respectively. do.

According to another aspect of the invention,

A first substrate, a second substrate having a gap and arranged opposite to the first substrate, a liquid crystal layer made of a liquid crystal held between the first and second substrates and having a negative anisotropic dielectric constant, the first direction and A plurality of pixel electrodes each having a major axis arranged on the first substrate in the form of a matrix in a second direction perpendicular to the first direction and extending in the first direction, and provided on the second substrate and overlapping the pixel electrodes; A liquid crystal display panel comprising a plurality of projections spaced from the side of the pixel electrode and measured toward the first substrate and configured to control the direction in which the liquid crystal molecules are aligned when measured in the first direction;

A first optical unit provided outside the first substrate and configured to receive light and radiate the light as a circularly polarized light to the liquid crystal display panel; and a circular polarized light provided outside the second substrate and incident through the liquid crystal display panel. An optical unit comprising a second optical unit configured to emit light as linearly polarized light,

The major axis of each pixel electrode has a length of 160 μm or less,

The value obtained by dividing the height of the projection by the gap d between the first and second substrates is 0.14 to 0.6,

The projection has a width of 15 μm or less when measured in the first direction,

The projections are stripe-shaped extending in the second direction, each provided on the pixel electrode along the second direction, arranged to divide the pixel electrode into two parts of substantially the same size, respectively, along the first direction,

Each of the first and second optical units includes a polarizing plate having a transmission axis and a phase contrast plate stacked on the polarizing plate with a transmission-easy axis having a phase difference of at least 1/4 and forming an angle of 30 to 60 ° with the transmission axis. A liquid crystal display device is provided.

According to another aspect of the invention,

A first substrate, a second substrate having a gap and arranged opposite to the first substrate, a liquid crystal layer made of a liquid crystal held between the first and second substrates and having a negative anisotropic dielectric constant, the first direction and A plurality of pixel electrodes each having a major axis arranged on the first substrate in the form of a matrix in a second direction perpendicular to the first direction and extending in the first direction, and provided on the second substrate and overlapping the pixel electrodes; A liquid crystal display panel comprising a plurality of projections spaced from the side of the pixel electrode and measured toward the first substrate and configured to control the direction in which the liquid crystal molecules are aligned when measured in the first direction;

A first optical unit provided outside the first substrate and configured to receive light and radiate the light as a circularly polarized light to the liquid crystal display panel; and a circular polarized light provided outside the second substrate and incident through the liquid crystal display panel. An optical unit comprising a second optical unit configured to emit light as linearly polarized light,

The major axis of each pixel electrode has a length of 160 μm or less,

The value obtained by dividing the height of the projection by the gap d between the first and second substrates is 0.14 to 0.6,

The projection has a width of 15 μm or less when measured in the first direction,

The projection is substantially semicircular and a liquid crystal display device is provided which is opposed to the central portions of the pixel electrodes, respectively.

Further advantages of the invention are described below, some of which are apparent from this description, or may be learned from the embodiments of the invention. The advantages of the invention can be realized and obtained by means and combinations particularly pointed out below.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and illustrate the principles of the invention, together with the alternative descriptions given above and the detailed description of the embodiments given below.

A liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in Figs. 1 to 3, the transmissive liquid crystal display device includes a liquid crystal display panel 1, an optical unit 2 and a backlight unit 3.

The liquid crystal display panel 1 includes an array substrate 4, an opposing substrate 5 arranged on the opposite side of the array substrate with a predetermined gap, and a liquid crystal layer 6 held between the array substrate 4 and the opposing substrate 5. ). The array substrate 4 is a first substrate. The opposing substrate 5 is a second substrate. The liquid crystal display panel 1 has a display area R1 overlapping the array substrate 4 and the opposing substrate 5. The liquid crystal display panel 1 has a plurality of pixel regions R2. The pixel region R2 has a transparent region R3 provided in the display region R1. Pixel region R2 is arranged in columns and rows to form a matrix. The columns extend in the first direction d1 and the rows extend in the second direction d2.

The array substrate 4 includes a glass substrate 10 that functions as a transparent insulating substrate. On the glass substrate 10, the scan line 11 and the signal line 12 are arranged in a matrix form in the display region R1. On the glass substrate 10, an auxiliary capacitance line 13 is also provided which extends parallel to the scan line. In this embodiment, each transparent zone R3 is surrounded by two adjacent scan lines 11 and two adjacent signal lines 12. On the glass substrate 10, one pixel unit 14 is formed for each pixel region R2.

One of the same pixel units 14 is described in detail.

The pixel unit 14 has a pixel electrode 18, a TFT 16 and an auxiliary capacitance element (not shown). The pixel electrode 18 is made of a transparent conductive film such as ITO (Indium Tin Oxide). The TFT 16 is connected to the pixel electrode 18, and the TFT 16 acts as a switching element. The TFT 16 and the auxiliary capacitance element are formed on the glass substrate 10 together with the scan line 11, the signal line 12, and the insulating layer 15. The inner layer insulating film 17 is formed on the insulating layer 15 and the TFT 16.

The pixel electrode 18 is formed on the inner layer insulating film 17 and connected to the TFT 16 through the contact hole 17a formed in the inner layer insulating film 17. The pixel electrode 18 has a main axis extending in the first direction d1. The edge of the pixel electrode 18 overlaps the scan line 11 and the signal line 12. Thus, the pixel electrode 18 overlaps the pixel region R2 and the transparent region R3. An alignment film 19 in the form of vertical alignment is formed on the glass substrate 10 and the pixel electrode 18.

The opposing substrate 5 includes a glass substrate 30 that functions as a transparent insulating substrate. In the display area, a red color layer 40R, a green color layer 40G, and a blue color layer 40B are formed on the glass substrate 30. Color layers 40R, 40G, 40B form color filter 40. A counter electrode 31 made of a transparent conductive film such as ITO is formed on the glass substrate 30 and the color filter 40.

A plurality of projections 32 are formed on the counter electrode 31. The projection portion 32 is provided on the counter electrode 31 and overlaps the pixel electrode 18. The projection portion 32 is positioned spaced apart from the opposite edge of the periphery of the pixel electrode 18 when viewed in the first direction d1. The projection portion 32 protrudes toward the array substrate 4. The projection part 32 controls the inclination direction in which the liquid crystal molecules 6a of the liquid crystal layer 6 opposite to the pixel electrode 18 are inclined. On the glass substrate 30 and the projection part 32, the alignment film 33 of a vertical alignment type is formed.

The array substrate 4 and the opposing substrate 5 are arranged to face each other with a gap by a cylindrical spacer (not shown) which functions as a spacer. The array substrate 4 and the opposing substrate 5 are joined together with a sealing member (not shown) provided at the edge portions of both substrates. The liquid crystal layer 6 is formed in a space surrounded by the array substrate 4, the opposing substrate 5 and the sealing member. The liquid crystal layer 6 is made of a fluorine liquid crystal material. The liquid crystal material is n-type, and has a Δn (anisotropic refractive index) of 0.09, a Δε (anisotropic dielectric constant) of −5, and a rotational viscosity coefficient of 100 mPa · S. As described above, the liquid crystal layer 6 is made of a liquid crystal material having a negative anisotropic dielectric constant.

The optical unit 2 includes a first optical unit 50 and a second optical unit 60. The first optical unit 50 is provided outside the array substrate 4. The second optical unit 60 is provided outside the opposing substrate 5. The first optical unit 50 has a phase contrast plate 51 and a polarizing plate 52. The phase contrast plate 51 has a phase difference of 1/4 and a transmission-easy axis 51a. The polarizing plate 52 is formed on the phase contrast plate 51 and has a transmission axis 52a that forms an angle of 45 ° with the transmission-easy axis 51a. The phase contrast plate 51 and the polarizing plate 52 are laminated one by one to form a laminate.

The second optical unit 60 has a phase contrast plate 61 and a polarizing plate 62. The phase contrast plate 61 has a phase difference of 1/4 and a transmission-easy axis 61a. The polarizing plate 62 is formed on the phase contrast plate 61 and has a transmission axis 62a which forms an angle of 45 ° with the transmission-easy axis 61a. The phase contrast plate 61 and the polarizing plate 62 are laminated one by one to form a laminate.

The backlight unit 3 is provided on the side of the outer surface of the polarizing plate 52. The backlight unit 3 has a light guide 3a, a light source 3b, and a reflector 3c. The light guide 3a is opposed to the polarizing plate 52 and includes a light guide plate. The light source 3b and the reflector 3c face one side of the light guide 3a.

Therefore, the first optical unit 50 receives the backlight and converts it into circularly polarized light applied to the liquid crystal display panel 1. The second optical unit 60 receives circularly polarized light transmitted through the liquid crystal display panel 1 and converts it to linearly polarized light. In this embodiment, the optical unit 2 operates in circular polarization mode.

In this mode, the ellipticity is set to 1 for light beams having a wavelength in the range from 530 to 580 nm.

The configuration of the liquid crystal display device described above will be described.

(First embodiment)

The first embodiment is a liquid crystal display device which can be used as a display unit of a portable terminal as can be seen from FIGS. 1, 2, 4, 5 and 8. The size of the display of the device is 2.4 inches (6.1 cm) diagonally. The apparatus has pixels arranged in 640 (vertical direction, or first direction d1) and 480 (horizontal direction, or second direction d2). The device is a VGA color active-matrix liquid crystal display device. Each pixel consists of three pixel units, red, green and blue units. Thus, the device has 640 (vertical direction) x 1440 (horizontal direction) pixels. The resolution (pixel pitch) is 332 ppi.

The size of the pixel unit 14 is 75 μm (vertical direction) × 25 μm (horizontal direction). The pixel electrode 18 is rectangular. The gap lp between the peripheral edges of any two adjacent pixel electrodes 18 is about 8 μm.

Projection 32 has a substantially semi-circular cross section. The projection is formed like a stripe and extends in the second direction d2 (thus extending parallel to the short side of each pixel electrode). The projection units 32 are provided corresponding to the pixel electrodes 18 arranged in the second direction one by one. Each projection 32 is located at a position (of the pixel center), so that two parts of substantially the same size are arranged side by side in the first direction d1 with one pixel electrode 18 provided in the transparent region R3. Divide by. The projection portion 32 has a width W of about 10 μm and a height h of about 1.5 μm in the first direction d1. The projection part is made of photosensitive acrylic resin. The display mode of the liquid crystal display device is a two-division MVA mode.

The array substrate 4 provided in the image element region R2 and not overlapping with the projection portion 32 is spaced apart from the opposing substrate 5 to form a gap d of 3 mu m. The height h of the projection part is half (0.5) of the gap d. The value h obtained by dividing the height h of the projection part 32 by the gap d is 0.5.

The liquid crystal display device is configured to satisfy the following relational expression (1).

MIN (la, lb) / d <10 .... (1)

Here, as shown in FIG. 5, la is the shortest between the projection portion 32 and the position coordinate P of the pixel electrode 18 overlapping the transparent region R3 without overlapping the projection portion 32. Distance, lb is the shortest distance between the position coordinate P and the end of the pixel electrode overlapping the transparent zone R3 closer to the position coordinate P than the other transparent zone, and MIN (la, lb) is such a distance. the smaller of la and lb.

In Fig. 5, at a given position coordinate P1 (la, lb) = (7 μm, 5 μm), MIN (la, lb) is 5 μm, and MIN (la, lb) / d is 1.7 (= 5/3 < 10). This value satisfies relation (1). Further, at the given position coordinates P2 and P3, MIN (la, lb) satisfies the relation (1) as described below.

P2 (la, lb) = (8 μm, 10 μm): MIN (la, lb) / d = 8/3 = 2.7 <10

P3 (la, lb) = (20 μm, 4 μm): MIN (la, lb) / d = 4/3 = 1.3 <10

The liquid crystal display device is configured such that the projection portion 32 is arranged to maximize the effective aperture ratio while satisfying the above relation (1). That is, the total area S (relative aperture ratio) of the pixel electrode 18 not overlapping with the projection but overlapping with the transparent region R3 is 34%, the maximum value.

As shown in Fig. 8, the liquid crystal display satisfies relation (1) and has a maximum total area S of the transparent pixel electrode. Nevertheless, the display device maintains sufficient alignment stability in all pixel regions R2. The transmittance is 3.3% and the contrast ratio is 450. Thus, the liquid crystal display device exhibits good optical characteristics.

(2nd Example)

The liquid crystal display device of the second embodiment is used, for example, as a display unit of a portable terminal. The display of the device is 2.8 inches (7.1 cm) diagonally, slightly larger than the display according to the first embodiment. The device has 640 (vertical) x 480 (horizontal) pixels. The device is a VGA color active-matrix liquid crystal display device. The resolution (ie pixel pitch p) is 286 ppi. The size of each pixel 14 is 90 μm × 30 μm.

The liquid crystal display according to the second embodiment satisfies the relation (1) given above. The projections 32 are arranged in an optimal state that satisfies the relation (1). That is, the projections are arranged so that the effective aperture ratio is maximum. The total area S (ie, relative aperture ratio) of the transparent pixel electrode is 45%, the maximum value.

As shown in Fig. 8, sufficient alignment stability is achieved in all pixel regions R2 of the liquid crystal display device satisfying relation (1) while the total area S of the transparent pixel electrode is maximum. The transmittance is 4.3% and the contrast ratio is 480. Thus, the liquid crystal display device according to the second embodiment exhibits good optical characteristics.

(Third Embodiment)

The liquid crystal display device according to the third embodiment is used as a display unit of a portable terminal, for example. The display of the device is diagonally 2.8 inches (7.1 cm) in size and as large as the display according to the second embodiment. The device has 640 (vertical) x 480 (horizontal) pixels. The device is a color liquid crystal display of VGA color active-matrix type. The device differs from the structure of the device according to the second embodiment only in that the projection 32 is formed such that it has a relatively large aspect ratio. More precisely, the projection 32 has a width W of about 7 μm and a height h of about 1.5 μm measured in the first direction d1.

The liquid crystal display according to the third embodiment satisfies the above relation (1). The projection part 32 is arrange | positioned so that the effective aperture ratio may be maximum in the range of the relational expression (1). The total area S (ie, relative aperture ratio) of the transparent pixel electrode is 48%, the maximum value.

As is apparent from Fig. 8, while the total area S of the transparent pixel electrode is maximum, sufficient alignment stability is achieved in all pixel regions R2 of the liquid crystal display device satisfying the relation (1). The transmittance is 4.6% and the contrast ratio is 500. Thus, the liquid crystal display device according to the third embodiment exhibits good optical characteristics.

 (Example 4)

The liquid crystal display device according to the fourth embodiment is used as a display unit of a portable terminal, for example. The display portion of the device is diagonally 2.8 inches (7.1 cm) in size and as large as the display portion according to the second and third embodiments. The device has 640 (vertical) x 480 (horizontal) pixels. The device is a color liquid crystal display of VGA color active-matrix type. The device differs from the device according to the second and third embodiments only in terms of the projection 32.

6 and 7, the projection portion 32 is provided on the opposing substrate 5 to overlap the pixel electrode 18. Each projection 32 is positioned to face the central portion of the pixel electrode 18 that overlaps the transparent zone R3. The projection part 32 is semicircular. The projection has a diameter D of about 15 μm (width W in the first direction d1, width in the second direction d2), and height h of about 1.5 μm. The projection portion 32 is made of ordinary photosensitive acrylic resin. Therefore, the projection portion can be provided at low cost.

The projections 32 are each provided for one pixel electrode 18. Each projection 32 is spaced apart from the sides of the pixel electrode 18 extending in the first and second directions d1 and d2, respectively. The liquid crystal display according to the fourth embodiment is an MVA mode in a continuous radial alignment form. Of course, the projection part 32 controls the direction in which the liquid crystal molecules 6a constituting the liquid crystal layer 6 are inclined. The liquid crystal molecules 6a of the liquid crystal layer 6 facing the projection portion 32 are aligned radially from the projection portion 32.

The liquid crystal display of the fourth embodiment satisfies the relation (1) given above. The relation (1) is satisfied at the position coordinates P4, P5, P6 and P7, for example. The projection part 32 is arrange | positioned in the optimal state so that an effective aperture ratio may be maximum in the range of the relation (1). The total area S (ie, relative aperture ratio) of the transparent pixel electrode is 48%, the maximum value.

As can be seen from Fig. 8, while the total area S of the transparent pixel electrode is maximum, sufficient alignment stability is achieved in all pixel regions R2 of the liquid crystal display device satisfying the relation (1). The transmittance is 4.6% and the contrast ratio is 500. Thus, the liquid crystal display according to the fourth embodiment shows good optical characteristics.

  (Example 5)

The liquid crystal display device according to the fifth embodiment is used as a display unit of a portable terminal, for example. The display of the device is diagonally 2.8 inches (7.1 cm) in size and as large as the display according to the second embodiment. The device has 640 (vertical) x 480 (horizontal) pixels. The device is likewise a color liquid crystal display of VGA color active-matrix type. The device differs from the device according to the second embodiment only in terms of the pixel electrode 18.

As shown in Figs. 9 and 10, unlike the second embodiment, each pixel element electrode 18 is arranged side by side in the first direction d1 and with respect to each other in the second direction by about IP / 4. It consists of two parts of equal size displaced. When viewed from the first direction or the second direction, any two adjacent portions have a symmetrical shape to each other.

The liquid crystal display according to the fifth embodiment satisfies the above relation (1). The relation (1) is satisfied at the position coordinates P8, P9, P10, for example. The projection part 32 is arrange | positioned in the optimal state so that an effective aperture ratio may be maximum in the range of the relation (1). The total area S (ie, relative aperture ratio) of the pixel electrode is at a maximum value.

Although the total area S of the transparent pixel electrode is maximum, sufficient orientation stability is achieved in all pixel regions R2 of the liquid crystal display device satisfying the relation (1), and all of the liquid crystal display apparatuses satisfying the relation (1). Sufficient alignment stability is achieved in the pixel region R2. The sides of each pixel electrode 18 separated by the projection portion 32 in the first direction d1 are asymmetric with each other. Therefore, the fifth embodiment is superior to the second embodiment in terms of alignment stability. The liquid crystal display device according to the fifth embodiment also exhibits good optical characteristics.

  (Example 6)

The liquid crystal display device according to the sixth embodiment is used as a display unit of a portable terminal, for example. The display of the device is diagonally 2.8 inches (7.1 cm) in size and as large as the display according to the second embodiment. The device has 640 (vertical) x 480 (horizontal) pixels. The device is likewise a color liquid crystal display of VGA color active-matrix type. The device differs from the device according to the fifth embodiment only in terms of the projection 32.

As shown in Figs. 11 and 12, the projection portion 32 is semicircular as in the fourth embodiment. Each projection 32 is provided on the center portion of the pixel electrode 18 overlapping the transparent region R3. The projection has a diameter D of about 15 μm (width W in the first direction d1, width in the second direction d2), and height h of about 1.5 μm. Each projection 32 is spaced apart from the sides of the pixel electrode 18 extending in the first and second directions d1 and d2, respectively.

The liquid crystal display device according to the sixth embodiment satisfies the relation (1) given above. The relation (1) is satisfied at the position coordinates P11, P12, P13, and P14, for example. The projection part 32 is arrange | positioned in the optimal state so that an effective aperture ratio may be maximum in the range of the relation (1). The total area S (ie, relative aperture ratio) of the transparent pixel electrode is at a maximum value.

The liquid crystal display device according to the sixth embodiment satisfies the relation (1), and obtains sufficient alignment stability while the total area S of the transparent pixel electrode is maximum. The sides of each pixel electrode 18 separated by the projection portion 32 in the first direction d1 are asymmetric with each other. Thus, the sixth embodiment has high alignment stability. Such a liquid crystal display device exhibits good optical characteristics.

In any structural features other than those described above, the second to sixth embodiments are the same as the first embodiment. Thus, the same elements as those of the first embodiment are denoted by the same reference numerals and have not been described in detail.

A comparative example of a liquid crystal display device having a lower transmittance and a smaller contrast ratio is described. The comparative example is similar to the above-described embodiments, and the same elements as those of any embodiment are denoted by the same reference numerals and are not described in detail.

(Comparative Example)

14, 15, and 16, the liquid crystal display according to the comparative example has a size of 2.4 inches (6.1 cm) diagonally. The device has 640 (vertical) x 480 (horizontal) pixels and is a VGA color active-matrix type color liquid crystal display device. The resolution (ie pixel pitch p) is 332 ppi.

The size of each pixel 14 is 75 μm × 25 μm. The pixel electrode 18 is rectangular.

The projection part 32 of the comparative example has a substantially semicircular cross section. The projection portion has a stripe shape extending in the first direction d1. Each projection portion 32 overlaps with the pixel electrodes 18 arranged in the first direction d1, and each pixel electrode 18 with the projection portion overlapping with the transparent region R3 is formed of the pixel electrode 18. It extends along the centerline as if it were divided into two parts of equal size. The projection portion 32 has a width W of about 10 μm and a height h of about 1.5 μm in the second direction d2. The display mode of the liquid crystal display device according to the comparative example is a two-division MVA mode.

The liquid crystal display device according to the comparative example satisfies relation (1). The relation (1) is satisfied at the position coordinates P15, P16, P17, for example. This apparatus satisfies the condition for displaying a high resolution image and has a projection portion 32 extending in the first direction d1. Therefore, the total area S (ie, relative aperture ratio) of the transparent pixel electrode is as low as 12% and the transmittance is as low as 1.1%. Also, the contrast ratio is as small as 100. Therefore, the liquid crystal display device according to the comparative example does not exhibit good optical characteristics.

This is inevitable because the ratio of the projection 32 to the pixel electrode 18 in terms of area increases more than the high resolution of the image and the reduced aperture ratio due to the projection 32. As a result, the effective aperture ratio decreases, and the amount of light passing through the projection portion 32 increases. Since the liquid crystal molecules are inclined at the edge of each projection 32 in advance, the amount of light passing through the projection 32 is increased.

In terms of transmittance and contrast ratio, it is preferable that the area occupied by the projection portion 32 in the transparent region R3 is reduced as much as possible. In the liquid crystal display device according to the comparative example, since the combination of high sharpness, high aperture ratio and high contrast ratio is in a balance relationship, it is difficult for them to coexist.

In the liquid crystal display according to the embodiment, the projection part 32 extends in the second direction d2 so that the pixel electrodes 18 are arranged side by side in the first direction d1 and have the same size as the stripe shape. Divide into 2 parts When the projections 32 are semicircular, each is provided on the center portion of the pixel electrode 18 and from the sides of the pixel electrode 18 extending in the first direction d1 and the second direction d2, respectively. Spaced apart. The projections 32 of the embodiment are arranged in an optimal state, so that the effective aperture ratio can be maximized within the range of the relation (1). Therefore, the total area S of the transparent pixel electrode can be maximized while satisfying the conditions for the device to display a high resolution image. The liquid crystal display device according to any embodiment of the present invention achieves good optical properties such as high transmittance and high contrast ratio. Since the liquid crystal display satisfies the relation (1) given above, the edge electric field of the projection part 32 and / or the pixel electrode 18 acts at all position coordinates P. Thus, the display portion can maintain sufficient alignment stability. Thus, the display portion exhibits high transmittance, high contrast ratio and high alignment stability.

In an embodiment of the invention, each projection 32 extends in the second direction d2. Therefore, the liquid crystal molecules 6a are arranged in the first direction d1 or the second direction d2. In other words, the liquid crystal molecules are aligned upward, downward, leftward and rightward of the display screen. Thus, the liquid crystal display has a larger time than when the projection portion 32 extends perpendicular to the diagonal.

The stripe projections 32 are arranged in such a way that the pixel electrodes 18 are divided into two parts each having the same size in the main axis direction. Two portions of each pixel electrode 18 have a square or similar shape to a square. The edge electric field applied to the liquid crystal 6 in the direction opposite to the first direction d1 and the edge electric field applied to the liquid crystal 6 in the direction opposite to the second direction d2 are each pixel electrode 18. It works the same on two parts of. Therefore, the liquid crystal molecules 6a are uniformly aligned in the first direction d1 and the second direction d2. In this case, of course, the vision is increased for both the vertical direction and the horizontal direction.

As shown in Fig. 13, the liquid crystal display device must have a specific reaction time in order to display an image of desired image quality. An embodiment of the present invention provides a reaction of at least 30 ms when the shortest distance between the side of each projection 32 in the first direction d1 and the corresponding end of one pixel electrode 18 is 80 μm or less. Take time. Accordingly, the liquid crystal display may display an image having a desired image quality when the shortest distance is 80 μm or less.

The device achieves high transmittance and high contrast ratio. Thus, the device displays a high resolution image. A liquid crystal display device for displaying a high resolution image can be provided with high yield and low cost.

The invention is not limited to the embodiment described above. Various changes and modifications can be made within the scope and spirit of the invention. For example, even though the total area S of the transparent pixel electrode is close to the maximum value, even if it is not the maximum value, the same advantages can be obtained as in the case where the total area S has the maximum value. As used herein, a value close to the maximum means at least 70% less than 100% of the maximum.

The major axis of the pixel electrode 18 should be 160 µm or less, more preferably 67.5 µm or less. The value of h / d should be 0.14 to 0.6. The projection portion 32 should have a width W of 15 μm or less when measured in the first direction d1. The projection portion 32 should have a height h of 0.5 to 2 m and a width d of 2 to 5 m, provided that the height to width, h / d ratio is in the range of 0.14 to 0.6. In the case of a stripe shape, the projection 32 may have a triangular cross section or any other polygonal cross section.

The phase contrast plates 51 and 61 satisfy that they have a phase difference of at least 1/4. The angle made by the transmission axis 52a and the transmission-easy axis 51a may range from 30 to 60 °. The angle created by the transmission axis 62a and the transmission-easy axis 61a may range from 30 to 60 degrees. The optical unit 2 may be set to a circular polarization mode or an elliptical polarization mode in which the ellipticity is 0.4 or more and does not exceed 1 in an optical beam having a wavelength in the range of 530 to 580 nm.

Alignment stability can be improved by forming slits, holes or notches in the pixel electrode 18 to improve the asymmetry of the electric field applied to the liquid crystal layer 6, or by optimizing the electric field response of the liquid crystal molecules 6a.

The liquid crystal display device can achieve the above-mentioned advantages even when the resolution (that is, the pixel pitch P) is 210 ppi or more. Several projections 32 can be stacked one on top of each pixel electrode. The liquid crystal display device is not limited to the transparent form, but may be a translucent form.

According to the present invention, it is possible to provide a liquid crystal display device with high definition that obtains high transmittance and high contrast ratio.

Claims (9)

It is a liquid crystal display device A first substrate, a second substrate having a gap and arranged opposite to the first substrate, a liquid crystal layer made of a liquid crystal held between the first and second substrates and having a negative anisotropic dielectric constant, the first direction and A plurality of pixel electrodes each having a major axis arranged on the first substrate in the form of a matrix in a second direction perpendicular to the first direction and extending in the first direction, and provided on the second substrate and overlapping the pixel electrodes; A liquid crystal display panel comprising a plurality of projections spaced from the side of the pixel electrode and measured toward the first substrate and configured to control the direction in which the liquid crystal molecules are aligned when measured in the first direction; A first optical unit provided outside the first substrate and configured to receive light and radiate the light as a circularly polarized light to the liquid crystal display panel; and a circular polarized light provided outside the second substrate and incident through the liquid crystal display panel. An optical unit comprising a second optical unit configured to emit light as linearly polarized light, The major axis of each pixel electrode has a length of 160 μm or less, The value obtained by dividing the height of the projection by the gap d between the first and second substrates is 0.14 to 0.6, The projection has a width of 15 μm or less when measured in the first direction, MIN (la, lb) / d <10, where la is the shortest distance between the pixel electrode position coordinates of the pixel electrodes and one of the projections overlapping the pixel electrode, lb is greater than the position coordinates and any other pixel electrode The shortest distance between the ends of the pixel electrode closer to the position coordinate, and MIN (la, lb) is the smaller of these distances la and lb. The liquid crystal display of claim 1, wherein the optical unit operates in an elliptical polarization mode or a circular polarization mode, wherein the elliptical polarization mode uses an ellipticity of at least 0.4 and not greater than 1 in an optical beam having a wavelength in the range of 530 to 580 nm. Device. 2. The projection of claim 1, wherein the projections have a stripe shape extending in a second direction, each provided on a pixel electrode along a second direction, and each dividing the pixel electrode into two parts of substantially the same size along the first direction. Arranged, The projection portion has a height in the range of 0.5 to 2 μm and a gap d in the range of 2 to 5 μm. 10. The apparatus of claim 1, wherein the projections are stripe-shaped extending in a second direction, each provided on a pixel electrode along a second direction, and arranged to divide the pixel electrode into two portions of approximately the same size along the first direction, respectively. Become, Each of the first and second optical units includes a polarizing plate having a transmission axis and a phase contrast plate stacked on the polarizing plate with a transmission-easy axis having a phase difference of at least 1/4 and forming an angle of 30 to 60 ° with the transmission axis. Liquid crystal display. The liquid crystal display device according to claim 1, wherein the projection portion is substantially semicircular and opposes with respect to the center portions of the pixel electrodes, respectively. The liquid crystal display of claim 1, wherein each pixel electrode is composed of two parts of the same size arranged side by side in a first direction and displaced with respect to each other in a second direction. It is a liquid crystal display device A first substrate, a second substrate having a gap and arranged opposite to the first substrate, a liquid crystal layer made of a liquid crystal held between the first and second substrates and having a negative anisotropic dielectric constant, the first direction and A plurality of pixel electrodes each having a major axis arranged on the first substrate in the form of a matrix in a second direction perpendicular to the first direction and extending in the first direction, and provided on the second substrate and overlapping the pixel electrodes; A liquid crystal display panel comprising a plurality of projections spaced from the side of the pixel electrode when measured in the first direction and protruding toward the first substrate and having a height in the range of 0.5 to 2 μm and configured to control the direction in which the liquid crystal molecules are aligned; , A first optical unit provided outside the first substrate and configured to receive light and radiate the light as a circularly polarized light to the liquid crystal display panel; and a circular polarized light provided outside the second substrate and incident through the liquid crystal display panel. An optical unit comprising a second optical unit configured to emit light as linearly polarized light, The major axis of each pixel electrode has a length of 160 μm or less, The first and second substrates are spaced apart by a gap d in the range of 2 to 5 μm, The projection has a width of 15 μm or less when measured in the first direction, The projection portion is a stripe shape extending in the second direction, each provided on the pixel electrode in the second direction, and arranged to divide the pixel electrode into two parts of substantially the same size in the first direction, respectively. It is a liquid crystal display device A first substrate, a second substrate having a gap and arranged opposite to the first substrate, a liquid crystal layer made of a liquid crystal held between the first and second substrates and having a negative anisotropic dielectric constant, the first direction and A plurality of pixel electrodes each having a major axis arranged on the first substrate in the form of a matrix in a second direction perpendicular to the first direction and extending in the first direction, and provided on the second substrate and overlapping the pixel electrodes; A liquid crystal display panel comprising a plurality of projections spaced from the side of the pixel electrode and measured toward the first substrate and configured to control the direction in which the liquid crystal molecules are aligned when measured in the first direction; A first optical unit provided outside the first substrate and configured to receive light and radiate the light as a circularly polarized light to the liquid crystal display panel; and a circular polarized light provided outside the second substrate and incident through the liquid crystal display panel. An optical unit comprising a second optical unit configured to emit light as linearly polarized light, The major axis of each pixel electrode has a length of 160 μm or less, The value obtained by dividing the height of the projection by the gap d between the first and second substrates is 0.14 to 0.6, The projection has a width of 15 μm or less when measured in the first direction, The projections are stripe-shaped extending in the second direction, each provided on the pixel electrode along the second direction, arranged to divide the pixel electrode into two parts of substantially the same size, respectively, along the first direction, Each of the first and second optical units includes a polarizing plate having a transmission axis and a phase contrast plate stacked on the polarizing plate with a transmission-easy axis having a phase difference of at least 1/4 and forming an angle of 30 to 60 ° with the transmission axis. Liquid crystal display. It is a liquid crystal display device A first substrate, a second substrate having a gap and arranged opposite to the first substrate, a liquid crystal layer made of a liquid crystal held between the first and second substrates and having a negative anisotropic dielectric constant, the first direction and A plurality of pixel electrodes each having a major axis arranged on the first substrate in the form of a matrix in a second direction perpendicular to the first direction and extending in the first direction, and provided on the second substrate and overlapping the pixel electrodes; A liquid crystal display panel comprising a plurality of projections spaced from the side of the pixel electrode and measured toward the first substrate and configured to control the direction in which the liquid crystal molecules are aligned when measured in the first direction; A first optical unit provided on the outside of the first substrate and configured to emit light to the liquid crystal display panel as circularly polarized light, and a circularly polarized light provided on the outside of the second substrate and incident through the liquid crystal display panel An optical unit comprising a second optical unit configured to emit such light as linearly polarized light, The major axis of each pixel electrode has a length of 160 μm or less, The value obtained by dividing the height of the projection by the gap d between the first and second substrates is 0.14 to 0.6, The projection has a width of 15 μm or less when measured in the first direction, And a projection portion is substantially semi-circular and opposing to the center portions of the pixel electrodes, respectively.

Images