JP2002365625A - Liquid crystal display device and electronic instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semitransmission reflection type liquid crystal display device excellent in visibility by enhancing display brightness in the transmission mode, in the semitransmission reflection type liquid crystal display device provided with the reflection mode and the transmission mode and to provide an electronic instrument provided therewith. SOLUTION: In the semitransmission reflection type liquid crystal display device wherein a liquid crystal 4 is interposed between an upper substrate 3 and a lower substrate 2, an upper polarizing plate 13 and a lower reflection polarizing layer 6 are provided on the upper and the lower sides of the liquid crystal 4, respectively, a backlight (illuminator) 5 is provided on the outer surface side of the lower substrate 2 and display is executed by switching the transmission mode and the reflection mode, the lower reflection polarizing layer 6 is provided partially on the inner surface side of the lower substrate 2 and a lower polarizing plate is provided on the lower side of the lower reflection polarizing layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and an electronic apparatus, and more particularly to a transflective liquid crystal display device capable of displaying sufficient brightness even in a transmission mode.

[0002]

2. Description of the Related Art A reflection type liquid crystal display device does not have a light source such as a backlight and therefore has low power consumption. However, since display is performed using external light such as natural light or illumination light, there is a problem that it is difficult to visually recognize the display in a dark place. Therefore, there has been proposed a liquid crystal display device in which external light is used in a bright place like a normal reflective liquid crystal display device, but in a dark place, the display can be visually recognized by an internal light source. In other words, this liquid crystal display device employs a display method having both a reflective type and a transmissive type, and reduces power consumption by switching to a reflective mode or a transmissive mode according to the surrounding brightness. In addition, a clear display can be performed even when the surroundings are dark. Hereinafter, in this specification, this type of liquid crystal display device is referred to as a “semi-transmissive reflective liquid crystal display device”.
That.

As a form of a transflective liquid crystal display device,
A liquid crystal display device has been proposed in which a reflective film in which a slit for light transmission is formed in a metal film such as aluminum is provided on the inner surface of a lower substrate. This is because by providing a metal film on the inner surface of the lower substrate, the influence of parallax due to the thickness of the lower substrate is prevented, and particularly in a structure using a color filter, color mixing is prevented.
FIG. 9 shows an example of a passive matrix type transflective liquid crystal display device. In this liquid crystal display device 100, a liquid crystal 103 is sandwiched between a pair of transparent substrates 101 and 102, a reflective film 104 and an insulating film 106 are stacked on a lower substrate 101, and indium tin oxide (Inditin oxide) is formed thereon.
um Tin Oxide, hereinafter abbreviated as ITO. ), A scan electrode 108 in the form of a stripe made of a transparent conductive film is formed, and an alignment film 107 is formed so as to cover the scan electrode 108. On the other hand, a color filter 109 is formed on the upper substrate 102, a flattening film 111 is laminated thereon, and a signal electrode 112 made of a transparent conductive film such as ITO is formed on the flattening film 111 with the scanning electrode 108. It is formed in a stripe shape in a direction perpendicular to the direction, and an alignment film 113 is formed so as to cover the signal electrode 112. Reflective film 10
Numeral 4 is formed of a metal film such as aluminum, and the reflection film 104 has a slit 110 for light transmission for each pixel.
Are formed. With this slit 110, the reflection film 104 functions as a transflective film. Also, upper substrate 1
02, the forward scattering plate 11 in order from the upper substrate 102 side.
8, a retardation plate 119 and an upper polarizing plate 114 are arranged, and a 波長 wavelength plate 115 and a lower polarizing plate 116 are provided outside the lower substrate 101.
Is provided. Further, a backlight 117 is disposed on the lower surface side of the lower substrate 101.

When the liquid crystal display device 100 having the above configuration is used in a reflective mode in a bright place, external light incident from above the upper substrate 102 passes through the liquid crystal 103 and is reflected on the surface of the reflective film 104, and then again. The upper substrate 1 that transmits the liquid crystal 103
It is emitted to the 02 side. When used in the transmissive mode in a dark place, the backlight 11 installed below the lower substrate 101
7 is reflected by the reflection film 1 at the slit 110 portion.
04 and then through the liquid crystal 103 to pass through the upper substrate 1
It is emitted to the 02 side. These lights contribute to display in each mode.

[0005]

The above liquid crystal display device 10
According to 0, although the display can be visually recognized regardless of the presence or absence of external light, there is a problem that the brightness in the transmission mode is insufficient compared to that in the reflection mode. This is because the amount of light that can mainly contribute to display in the transmission mode is only the amount of light passing through the slit 110 provided in the reflective film 104, and the と wavelength plate provided on the outer surface side of the lower substrate 101 115 and the polarizing plate 116.

In the liquid crystal display device 100 shown in FIG.
When performing display in the transmission mode, the backlight 11
The light emitted from 7 enters the liquid crystal display unit from the outside of the lower substrate 101, and of the light, the light that has passed through the slit 110 becomes light that contributes to display. Here, in order to perform dark display in the liquid crystal display device 100, the slit 1
Light traveling from 10 to the upper substrate 102 needs to be circularly polarized light. Therefore, since the light emitted from the backlight 117 and passing through the slit 110 needs to be circularly polarized light, a 波長 wavelength for converting linearly polarized light transmitted through the lower polarizing plate 116 into circularly polarized light is used. A plate 115 is required.

Next, focusing on the light that does not pass through the slit 110 among the light emitted from the backlight 117, the light emitted from the backlight 117 and the lower polarizing plate 116
, And becomes linearly polarized light parallel to the paper surface, passes through the 波長 wavelength plate 115, becomes circularly polarized light, and reaches the reflection film 104. Further, when the light is reflected by the surface of the reflection film 104 on the lower substrate 104 side, the light becomes reversely-polarized circularly polarized light.
After passing through 15, the light becomes linearly polarized light perpendicular to the paper surface. Then, the light is absorbed by the lower polarizing plate 116 having a transmission axis parallel to the paper surface. That is, the light emitted from the backlight 117 does not pass through the slit 110 and is
Almost all of the light reflected on the back surface side of 4 is absorbed by the lower polarizing plate 116 of the lower substrate 101.

Further, when attention is paid to a case where bright display in the transmission mode is performed in the liquid crystal display device shown in FIG.
3 and the upper polarizer 114 of the upper substrate 102 without being affected by
, And is emitted to the upper side of the liquid crystal display device.
Since the light is circularly polarized by 15, about half of the light is absorbed by the upper polarizing plate 114 when passing through the upper polarizing plate 114 having a transmission axis parallel to the paper surface.

For the above two reasons, the liquid crystal display device 100 cannot make the display in the transmission mode bright.

In order to solve the above-mentioned problem, a liquid crystal display having the structure shown in FIG. 10 has been proposed. In a liquid crystal display device 200 shown in FIG. 10, a liquid crystal 203 is sandwiched between a pair of transparent substrates 201 and 202, a reflective polarizing layer 204 and an insulating layer 206 are laminated on a lower substrate 201, and an ITO or other material is formed thereon. A scan electrode 208 in the form of a stripe made of a transparent conductive film is formed, and an alignment film 207 is formed so as to cover the scan electrode 208. On the other hand, a color filter 209 is formed on the upper substrate 202, a flattening film 211 is laminated thereon, and a signal electrode 212 made of a transparent conductive film such as ITO is formed on the flattening film 211 with the scanning electrode 208. It is formed in a stripe shape in a direction perpendicular to the direction, and an alignment film 213 is formed so as to cover the signal electrode 212. The reflective polarizing layer 204 is formed by forming fine openings with a width of about 50 nm in a slit shape at a pitch of 150 nm to 400 nm in a metal film such as aluminum. Light incident on the reflective polarizing layer 204 is such that polarized light parallel to the slit-shaped opening is reflected, and polarized light perpendicular to the opening is transmitted. Also, the upper substrate 20
2, the forward scattering plate 21 is arranged in order from the upper substrate 202 side.
8, a retardation plate 219 and an upper polarizing plate 214 are arranged. Further, a backlight 217 is arranged on the lower surface side of the lower substrate 201.

In the liquid crystal display device 200 having the above structure, unlike the liquid crystal display device 100 shown in FIG. 9 in the transmission mode, the light incident on the upper polarizing plate 214 is not circularly polarized light but linearly polarized light. The display in the transmission mode can be made brighter than the display device 100.
The light reflected without passing through the reflective polarizing layer 204 is
The liquid crystal is returned to the backlight 217 and repeatedly reflected between the reflective polarizing layer 204 and the backlight 217. As a result, the polarization state changes and the light can pass through the reflective polarizing layer 204. Backlight 2
17 lights can be used effectively.

However, when the liquid crystal display device 200 having the above configuration is used in the transmission mode, the liquid crystal display device
When external light enters at 00, the contrast of the liquid crystal display device 200 is significantly reduced, and depending on the intensity of the external light, the display may not be visible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a transflective liquid crystal display device having a reflective mode and a transmissive mode, the display brightness in the transmissive mode is improved. A first object is to provide a transflective liquid crystal display device having excellent visibility. A second object of the present invention is to provide an electronic apparatus provided with the above transflective liquid crystal display device having excellent visibility.

[0014]

In order to achieve the above object, a liquid crystal display device according to the present invention comprises a liquid crystal sandwiched between an upper substrate and a lower substrate which are opposed to each other, and upper and lower polarizations of the liquid crystal. A transflective liquid crystal display device provided with a layer and a reflective polarizing layer, provided with an illuminating device on the outer surface side of the lower substrate, and performing display by switching between a transmission mode and a reflection mode, wherein the lower reflection polarizing layer Is provided partially on the inner surface side of the lower substrate, and a lower polarizing layer is provided below the lower reflective polarizing layer.

According to the structure of the present invention, the brightness of the display in the transmission mode can be remarkably improved, and the problem of the liquid crystal display device 200 shown in FIG. 10 can be solved. Can be prevented from lowering the contrast even when light is incident. These effects will be described in detail below with reference to FIGS.

FIGS. 3A and 3B are explanatory diagrams for explaining the operation principle of the liquid crystal display device of the present invention. FIG. 3A shows a light path in a transmission mode, and FIG. 3B shows a light path in a reflection mode. I have.
These drawings show only components necessary for the description among the components of the liquid crystal display device of the present invention.
An upper polarizing plate 54 and a lower reflective polarizing layer 51 are provided vertically above and below, and a lower polarizing layer 55 is formed between the lower reflective polarizing layer 51 and the lower substrate 50. An illumination device 58 is provided on the outer surface side (the lower surface side in the figure) of the lower substrate 50, and a reflection plate 59 is provided on the outer surface side of the illumination device 58.

The upper polarizing plate 54 has a transmission axis in a direction perpendicular to the paper surface, and the lower polarizing layer 55 has a transmission axis parallel to the paper surface. Further, the lower reflective polarizing layer 51 has a transmission axis in a direction perpendicular to the paper surface and a reflection axis parallel to the paper surface. The lower reflective polarizing layer 51 is provided with an illumination device 58.
There is provided an opening 51a for transmitting the light emitted from.

Hereinafter, a case where display is performed in the transmission mode shown in FIG. 3A will be described. First, focusing on light passing through the opening 51a, which is light used for display, the light emitted from the illumination device 58 passes through the lower substrate 50, and then has a lower polarization layer having a transmission axis parallel to the plane of the drawing. The light is converted into polarized light parallel to the plane of the drawing by the light 55, and enters the liquid crystal 53 through the opening 51 a. At this time, if a voltage is applied to the liquid crystal 53 (on state), the light incident on the liquid crystal 53 is hardly affected by the liquid crystal 53 and the upper polarizing plate 5
4 and an upper polarizer 54 having a transmission axis perpendicular to the paper surface.
Is absorbed by In this way, the pixels are darkly displayed. On the other hand, when no voltage is applied to the liquid crystal 53 (off state), the light incident on the liquid crystal 53 is converted into polarized light perpendicular to the paper by the optical rotation of the liquid crystal 53 and reaches the upper polarizing plate 54. . And the upper polarizing plate 5
This light, which is polarized light parallel to the transmission axis of
And pixels are displayed brightly.

Here, of the light transmitted through the lower polarizing layer 55, the light which does not pass through the opening 51a and is reflected on the back surface side (the lower substrate 50 side) of the reflective polarizing layer 51 is considered. The light reflected by the reflective polarizing layer 51 is directed toward the lower substrate 50 side, passes through the lower polarizing layer 55 and the lower substrate 50, returns to the lighting device 58, is reflected by the reflector 59 on the outer surface side of the lighting device 58, The light is reused as light traveling toward the lower polarizing layer 55 again. Then, this light is reflected by the reflection polarizing layer 51 and the reflection plate 59.
While passing through the opening 51a while repeating the reflection between
Used as light that contributes to display. Therefore, in the liquid crystal display device of the present invention, the light emitted from the lighting device 58 is not absorbed by the lower polarizing layer 55, and thus the lighting device 58 is not absorbed.
The efficiency of use of light emitted from the device can be increased, and a bright display can be obtained.

Next, a case where display is performed in the reflection mode shown in FIG. 3B will be described. As shown in FIG. 3B, light incident from above the upper polarizing plate 54 is first converted into polarized light perpendicular to the paper surface by the upper polarizing plate 54 having a transmission axis perpendicular to the paper surface, and is incident on the liquid crystal 53. I do. Next, when the liquid crystal is in the ON state, the incident light reaches the lower reflective polarizing layer 51 with little effect from the liquid crystal 53. The lower reflective polarizing layer 51 is a layer having a transmission axis perpendicular to the paper surface and a reflective axis parallel to the paper surface.
Reaches the lower reflective polarizing layer 51, and
0, the lower polarizing plate 55 having a transmission axis parallel to the paper surface.
Is absorbed by In this way, the pixels are darkly displayed.

On the other hand, when the liquid crystal 53 is in the off state, the light incident on the liquid crystal 53 is converted into polarized light parallel to the paper surface by the optical rotation of the liquid crystal 53, and reaches the lower reflection polarizing layer 51.
The lower reflection polarizing layer 51 having a reflection axis parallel to the paper surface.
And is again converted into polarized light perpendicular to the paper by the optical rotation of the liquid crystal 53, and transmitted through the upper polarizing plate 54. In this way, the pixels are brightly displayed.

As described above, in the liquid crystal display device of the present invention, display can be performed without providing the quarter-wave plate 115 outside the lower substrate 101 as in the liquid crystal display device 100 shown in FIG. . Accordingly, since there is no conversion from linearly polarized light to circularly polarized light or from circularly polarized light to linearly polarized light, there is no light loss accompanying these conversions. As a result, a bright display can be obtained, and particularly, the brightness in the transmission mode can be significantly improved.

Next, the operation of the conventional liquid crystal display device 200 shown in FIG. 10 will be described with reference to FIG. FIG. 4 is an explanatory diagram for explaining the operation of the liquid crystal display device 200, and shows only those components necessary for the description among the components shown in FIG. That is, the liquid crystal 203, the upper polarizing plate 214 disposed above and below it, the reflective polarizing layer 204, the lower substrate 201, and the lower substrate 20
1, only the backlight 217 arranged on the outer surface side of FIG.

First, the transmission mode shown in FIG. In the liquid crystal display device 200, light emitted from the backlight (illumination device) 217
1 and reaches the reflective polarizing layer 204. Since this reflective polarizing layer 204 has a transmission axis perpendicular to the paper surface and a reflection axis parallel to the paper surface, a part of the light reaching the reflective polarizing layer 204 is converted into polarized light perpendicular to the paper surface to the liquid crystal 203. Incident. If the liquid crystal 203 is on, the liquid crystal 2
03, which reaches the upper polarizer 214 with little effect, and which has a transmission axis perpendicular to the paper surface.
Through. In this way, the pixels are brightly displayed. On the other hand, when the liquid crystal 203 is in the off state, the light incident on the liquid crystal 203 is converted into polarized light parallel to the paper surface by the optical rotation of the liquid crystal 203, reaches the upper polarizing plate 54, and has a transmission axis perpendicular to the paper surface. The light is absorbed by the polarizing plate 54. In this way, the pixels are darkly displayed.

Next, the reflection mode shown in FIG. 4B will be described. As shown in FIG. 4B, the upper polarizing plate 214
Is incident on the liquid crystal 203 after being converted by the upper polarizing plate 214 having a transmission axis perpendicular to the paper into polarized light perpendicular to the paper. When the liquid crystal 203 is in the ON state, the incident light directly reaches the reflective polarizing plate 204, and the reflective polarizing plate 204 having a transmission axis perpendicular to the paper surface.
After passing through the substrate 201, the backlight 21
The light is emitted to the side 7. In this way, the pixels are darkly displayed. On the other hand, when the liquid crystal 203 is in the off state, the light incident on the liquid crystal 203 is converted into polarized light parallel to the plane of the drawing by the optical rotation of the liquid crystal 203, and the reflection polarizing plate 204
To reach. Here, since the reflection polarizing plate 204 has a reflection axis parallel to the paper surface, this light is reflected, and
3 is incident. Then, the light is converted into polarized light perpendicular to the paper surface by the optical rotation of the liquid crystal 203, and is transmitted through the upper polarizing plate 214. In this way, the pixels are brightly displayed.

In the liquid crystal display device 200, the problem that the contrast is greatly reduced when external light enters the liquid crystal display device 200 in the transmission mode is that the liquid crystal corresponding to the bright display and the dark display in the transmission mode and the reflection mode. Are different from each other in on / off state. That is, when the pixels are displayed brightly, the liquid crystal is in the on state in the transmission mode, but is in the off state in the reflection mode. For this reason, for example, when external light is incident on the liquid crystal display device 200 in a state where the liquid crystal display device 200 is used in the transmission mode, the incident external light is reflected and reflected in a dark display pixel (a pixel to which no voltage is applied to the liquid crystal). The light is reflected on the upper surface of the layer 204, passes through the upper substrate 201, and is emitted above the liquid crystal display device 200. For this reason, pixels that should be displayed darkly become brightly displayed, and as a result, the contrast is reduced, and in some cases, the display cannot be visually recognized.

On the other hand, in the liquid crystal display device of the present invention, as shown in FIGS. 3 (a) and 3 (b), in the bright display state in the transmission mode and the bright display state in the reflection mode, The liquid crystal 53 is turned off in both modes in dark display. Therefore, when the device is used in the transmission mode, even if external light is incident, the liquid crystal 53 is turned on in the dark display pixel.
As shown in FIG. 3B, external light incident on the liquid crystal 53 is absorbed by the lower polarizing layer 55 provided between the lower reflective polarizing layer 51 and the lower substrate 50. Therefore, the above-mentioned liquid crystal display device 20
The contrast such as 0 is not reduced.

Further, in the liquid crystal display device of the present invention, the lower polarizing layer 55 is provided on the lower substrate 50 side as shown in FIG.
The contrast can be made higher than 0. this is,
In the liquid crystal display device 200 shown in FIG. 4B, external light passes through the upper polarizing plate 214, the liquid crystal 203, and the reflective polarizing layer 203, and then is emitted toward the backlight 217. This is because, in the liquid crystal display device of the present invention, the external light incident on the dark display pixel passes through the upper polarizing plate 54, the liquid crystal 53, and the lower reflective polarizing layer 51, and is then absorbed by the lower polarizing layer 55. That is, in the liquid crystal display device 200 shown in FIG. 4B, the light emitted to the backlight 217 side is
In some cases, the light is reflected by a reflector (not shown) provided on the outer surface side of the backlight 217 and becomes light directed to the liquid crystal 203 side, which may make a dark display brighter and lower contrast. This is because the liquid crystal display device of the present invention does not return to the liquid crystal 53 side after being absorbed by the lower polarizing plate 55.

As described above, according to the liquid crystal display device of the present invention, the light emitted from the illuminating device can be used more effectively than the conventional transflective liquid crystal display device. The brightness of the display in the mode can be significantly improved. In addition, since the on / off state of the liquid crystal corresponding to the light and dark display is the same in the transmission mode and the reflection mode, even when external light enters in the transmission mode, the contrast does not decrease and a clear display is obtained. Can be Further, in the dark display in the reflection mode, by adopting a structure in which the light transmitted through the liquid crystal is absorbed by the lower polarizing layer, the dark display can be made darker, so that the contrast in the reflection mode can be improved.

Next, the liquid crystal display device of the present invention may have a configuration in which a reflective polarizing plate having a transmission axis substantially parallel to the transmission axis of the lower polarizing layer is provided on the outer surface side of the lower polarizing layer. . With such a configuration, light emitted from the lighting device can be more efficiently used for display, and display in the transmission mode can be made brighter. This configuration will be described in detail below with reference to FIG.

FIG. 5 is an explanatory diagram showing a main part of a liquid crystal display device according to the present invention employing the above configuration. The liquid crystal display device shown in this figure differs from the liquid crystal display device shown in FIG. 3 only in that a reflective polarizing plate is provided on the outer surface side of the lower substrate. Accordingly, in the following, the reflection polarizing plate 5 shown in FIG.
Only the operation of No. 7 will be described in detail. Also, among the components shown in FIG. 5, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

The reflection polarizing plate 57 shown in FIG. 5 is a reflection polarizing plate having a transmission axis parallel to the paper and a reflection axis perpendicular to the paper. The display principle of this liquid crystal display device is shown in FIG.
This is almost the same as the transmission mode of the liquid crystal display device shown in (a), and the light emitted from the illuminating device 58 is transmitted by the reflective polarizing plate 57 having a transmission axis parallel to the plane of the drawing, only the polarization component parallel to the plane of the drawing. Then, the light passes through the lower substrate 50 and the lower polarizing layer 55. Then, the light passes through the opening 51 a of the lower reflective polarizing layer 51 and enters the liquid crystal 53. Here, when the liquid crystal 53 is in the ON state, the incident light reaches the upper polarizing plate 54 as it is, and is absorbed by the upper polarizing plate having a transmission axis perpendicular to the paper surface, so that pixels are displayed in a dark state. I have. Alternatively, when the liquid crystal 53 is in the off state, the incident light is converted into polarized light perpendicular to the paper by the optical rotation of the liquid crystal 53 and transmitted through the upper polarizing plate 54. In this way, the pixels are brightly displayed.

Since the liquid crystal display device shown in FIG. 5 is provided with the reflective polarizing plate 57, a brighter display can be obtained than the liquid crystal display device shown in FIG. This is because in the liquid crystal display device shown in FIG. 3, about half of the light emitted from the illumination device 58 is absorbed by the lower polarizing layer 55, whereas in the liquid crystal display device having the configuration shown in FIG. This is because light absorption by the layer 55 does not occur.

That is, since the reflection polarizing layer 57 is provided, the components of the light emitted from the illumination device 58 other than the components parallel to the transmission axis (parallel to the paper surface) of the reflection polarizing plate 57 are used. And returns to the lighting device 58. After that, the light is reflected by the reflection plate 59 provided on the outer surface side of the illumination device 58, so that the light is reflected between the reflection polarizing plate 57 and the reflection plate 59. As this reflection is repeated, the polarization state of the light changes, and a part of the light passes through the reflective polarizing plate 57. When the light transmitted through the reflective polarizing plate 57 passes through the opening 51a, it becomes light that contributes to display. Further, of the light transmitted through the reflective polarizing plate 57, the light that does not pass through the opening 51 a and is reflected on the back surface side of the lower reflective polarizing layer 51 is also reflected by the lower reflective polarizing layer 51 and the reflecting plate 59.
Since the reflection is repeated during the period, the light can be incident on the opening 51a during the repeated reflection and contribute to the display. As described above, the amount of light incident on the opening 51a increases, and the brightness of display in the transmission mode can be improved.

Next, in the liquid crystal display device of the present invention,
It is preferable that an angle formed between the transmission axis of the lower polarizing layer and the transmission axis of the reflective polarizing plate is in a range of −30 ° to 30 °.

In the liquid crystal display device shown in FIG. 5, of the light transmitted through the reflective polarizing plate 57, components other than the component parallel to the transmission axis of the lower polarizing layer 55 are absorbed by the lower polarizing layer 55. The angle between the transmission axis of the layer and the transmission axis of the reflective polarizer is
Of course, it is most desirable that the angle is 0 ° (both are parallel), but practically, if the angle between the transmission axes of the two is within ± 30 °. If the angle formed by both transmission axes exceeds the above range, the amount of light absorbed by the lower polarizing layer 55 increases, and the above effect of brightening the display cannot be obtained.

Next, in the liquid crystal display device of the present invention, the lower polarizing layer may be provided on the outer surface side of the lower substrate. That is, a configuration in which a polarizing plate is provided on the outer surface side of the lower substrate may be employed. According to such a configuration, the liquid crystal display device can be configured using a polarizing plate generally used in the related art, so that the liquid crystal display device of the present invention can be easily manufactured.

Next, in the liquid crystal display device of the present invention, it is preferable that a scattering layer for scattering light reflected by the lower reflective polarizing layer is provided above the lower reflective polarizing layer. . According to such a configuration, it is possible to prevent the intensity of light reflected by the lower reflective polarizing layer from increasing in a specific direction, so that a liquid crystal display device with excellent visibility can be provided.

As the above-mentioned scattering layer, there can be mentioned, for example, a layer having a light scattering function formed immediately above the lower reflection polarizing layer or on the inner surface side of the upper substrate. Or,
A forward scattering plate may be provided on the outer surface side of the upper substrate.

Next, in the liquid crystal display device of the present invention, the upper polarizing layer may be provided on the inner surface side of the upper substrate. According to such a configuration, it is not necessary to separately provide a polarizing plate on the outer surface side of the upper substrate, so that manufacturing cost can be reduced. In addition, since such a polarizing layer can be formed continuously with the process of forming a color filter, a flattening film, and the like on the inner surface side of the upper substrate, the liquid crystal of the present configuration can be used without greatly changing the manufacturing process. A display device can be manufactured.

Next, in the liquid crystal display device of the present invention, it is preferable that the transmission axis of the lower reflective polarizing layer and the transmission axis of the lower polarizing layer are substantially orthogonal. With such a configuration, when performing a dark display in the reflection mode, almost all of the light transmitted through the lower reflective polarizing layer can be absorbed by the lower polarizing layer. The contrast can be improved.

Next, in the liquid crystal display device of the present invention,
The angle formed between the transmission axis of the lower reflective polarizing layer and the transmission axis of the lower polarizing layer is preferably in the range of 60 ° or more and 120 ° or less.

In the reflection mode shown in FIG. 3B, when performing dark display, external light incident on the liquid crystal display device is
The lower polarizing layer 55 is finally absorbed by the lower polarizing layer 5 of the light transmitted through the lower reflective polarizing layer 51.
The component parallel to the transmission axis 5 passes through the lower polarizing layer 55 and is emitted toward the illumination device 58 side. When this light is reflected by the reflection plate 59 and returns to the liquid crystal 53, the dark display becomes bright and the contrast is reduced. Therefore, the angle formed between the transmission axis of the lower polarizing layer 55 and the transmission axis of the lower reflective polarizing layer 51 is 90 °.
Of course, it is most preferable that both angles are perpendicular to each other, but if the angle between the transmission axes of the two is within ± 30 °, it can be used practically. If the angle formed by both transmission axes exceeds the above range, the amount of light transmitted through the lower polarizing layer 55 increases, and the contrast of the liquid crystal display device decreases.

Next, in the liquid crystal display device of the present invention,
A configuration in which a color filter is provided on the inner surface side of the upper substrate or the lower substrate may be employed. According to such a configuration, it is possible to realize a liquid crystal display device having good visibility, particularly by suppressing parallax in the reflection mode and preventing color mixing.

Next, in the liquid crystal display device of the present invention,
The lower reflective polarizing layer may have a structure in which a dielectric interference film having a prism shape is laminated.

The lower reflective polarizing layer according to the liquid crystal display device of the present invention will be described below with reference to FIG. FIG. 6 is a perspective view showing an example of a reflective polarizing layer formed by laminating a dielectric interference film having a prism shape. The reflective polarizing layer shown in FIG. 6 is formed on a substrate 60 having periodic grooves formed on the surface thereof.
This is a so-called three-dimensional photonic crystal layer formed by alternately laminating a plurality of layers 61 made of i and layers 62 made of SiO ₂ . As described above, the photonic crystal having the configuration in which the layers forming the prism shape are laminated has anisotropic light propagation characteristics. When light is incident from the upper side in the drawing, the incident light The component in the direction perpendicular to the groove of the substrate 60 is transmitted through the photonic crystal, and the component parallel to the groove is reflected. That is, the light Et transmitted through the reflective polarizing layer shown in FIG. 6 becomes polarized light perpendicular to the groove of the substrate 60, and the reflected light Er becomes polarized light parallel to the groove. The lamination pitch D of the layers 61 and 62 is 0.5 μm.
m, and the pitch P of the grooves formed on the substrate 60
Is about 0.5 μm.

In the liquid crystal display device shown in FIG. 3, the lower reflective polarizing layer having the above structure is arranged such that the transmission axis is perpendicular to the plane of FIG. That is, the grooves of the substrate 60 shown in FIG. 6 are arranged so as to be parallel to the paper surface of FIG.
An opening for transmitting light from the lighting device is provided in a part of the reflective polarizing layer.

Next, in the liquid crystal display device of the present invention, the lower reflective polarizing layer may have a structure in which a plurality of fine slit-shaped openings are provided in a metal reflective film. This configuration will be described in detail below with reference to FIG. FIG. 7 is a perspective view showing an example of a reflective polarizing layer in which a plurality of fine slits are provided in a metal reflective film. The reflective polarizing layer shown in FIG. 7 is obtained by forming a plurality of slits 72 at a predetermined pitch on a metal reflective film 71 of high reflectivity such as aluminum or silver formed on a substrate 70. The plurality of slits 72 are parallel to each other, and the slit width Ps is substantially the same for each slit 72. Although the size of each part is not particularly limited, the thickness d of the metal reflection film 71 is 100 to 400 n.
m, and the width Ps of the slit 72 is 30 nm to 3 nm.
And the width Pm of one metal reflection film 71 is 3
It is 0 nm to 300 nm. The reflective polarizing layer having such a configuration is configured such that, when light is incident from the upper surface side, a component parallel to the length direction of the slit 72 is reflected, and a component perpendicular to the length direction of the slit 72 is transmitted. Has become. That is, the light Et transmitted through the reflective polarizing layer shown in FIG. 7 becomes polarized light perpendicular to the slit 72, and the light Er reflected by the reflective polarizing layer becomes polarized light parallel to the slit 72.

In the liquid crystal display device shown in FIG. 3, the lower reflective polarizing layer having the above structure is arranged such that the transmission axis is perpendicular to the plane of FIG. That is, the slit 7 shown in FIG.
2 are arranged so that the length direction is parallel to the paper surface of FIG. In addition, an opening for transmitting light of the lighting device is provided in a part of the reflective polarizing layer.

Next, an electronic apparatus according to the present invention includes the above-described liquid crystal display device according to the present invention. According to this configuration, it is possible to realize an electronic device including an excellent display unit capable of obtaining a much brighter display in the transmission mode.

[0051]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a partial cross-sectional structure of the liquid crystal display device of the present embodiment. This embodiment is an example of a passive matrix type transflective color liquid crystal display device. In the following drawings, the thickness of each component, the ratio of dimensions, and the like are appropriately changed in order to make the drawings easy to see.

As shown in FIG. 1, in the liquid crystal display device 1 of the present embodiment, a lower substrate 2 and an upper substrate 3 are arranged to face each other, and an STN (Super Twiste
d Nematic) A liquid crystal panel 1 having a liquid crystal 4 composed of liquid crystal sandwiched therebetween, and a liquid crystal panel 1 having a schematic configuration, and a backlight (illumination device) 5 provided on the rear side of the liquid crystal panel 1 (outer side of the lower substrate 2). It is provided with a schematic configuration. On the inner surface side of the lower substrate 2 made of glass, resin, or the like, a lower reflective polarizing layer 6 having the same configuration as that shown in FIG. A scanning electrode 8 made of a transparent conductive film such as ITO extends in a horizontal direction in the drawing, and an orientation film 9 made of polyimide or the like is laminated so as to cover the scanning electrode 8. The lower reflection polarizing layer 6
Is provided with a slit (opening) 10 for transmitting light emitted from the backlight 5 for each pixel. A lower polarizing plate 20 is provided on the outer surface of the lower substrate 2.
And the reflective polarizing plate 21 are provided in this order. The transmission axis of the lower polarizer 20 and the transmission axis of the reflective polarizer 21 are arranged so as to be substantially parallel.

On the other hand, the upper substrate 3 made of glass, resin, etc.
On the inner surface side, red, green and blue color filters 11 extend in a direction perpendicular to the paper surface and are arranged repeatedly in this order so as to be orthogonal to the scanning electrodes 8 of the lower substrate 2. A flattening film 12 for flattening the unevenness formed by the color filter 11 is laminated. A striped electrode 14 made of a transparent conductive film such as ITO extends on the flattening film 12 in a direction perpendicular to the plane of the drawing.
An alignment film 15 made of polyimide or the like is formed on the electrode 14 by lamination. On the outer surface side of the upper substrate 3, a forward scattering plate 16, a retardation plate 17, and an upper polarizing plate 13 are provided in that order on the upper substrate 3. On the lower surface side of the backlight 5 (the side opposite to the liquid crystal panel 1), a reflection plate 1 is provided.
8 are provided.

As shown in FIG. 7, the lower reflective polarizing layer 6 is formed by coating a metal film made of aluminum, silver, or the like with a width of 30 to 30 mm.
A plurality of fine slit-shaped openings of 300 nm are formed in parallel with each other, and the direction of the slit-shaped openings is substantially parallel to the transmission axis of the lower polarizing plate 20. That is, the transmission axis of the lower reflective polarizing layer 6 and the transmission axis of the lower polarizing plate 20 are arranged so as to be substantially orthogonal to each other. Thereby, the light transmitted through the lower reflective polarizing layer 6 in the reflection mode can be efficiently absorbed by the lower polarizing plate 20, so that the dark display in the reflection mode is darkened and the contrast of the liquid crystal display device is improved. Can be.

The liquid crystal display device of the present embodiment having the above-described basic configuration is formed by forming the lower reflective polarizing layer 6 inside the lower substrate 2, and it is essential to provide the lower reflective substrate on the outer surface side of the conventional lower substrate. The existing quarter-wave plate is omitted. With such a configuration, the liquid crystal display device of the present embodiment is
In both the reflection mode and the transmission mode, a display with excellent visibility is possible. In particular, in the transmission mode, since the quarter-wave plate is not provided on the outer surface side of the lower substrate 2, the light emitted from the backlight 5 is reflected on the back surface side of the lower reflective polarizing layer 6, and The light returning to the liquid crystal panel 1 can be reflected by the reflector 18 and returned to the liquid crystal panel 1 again. Therefore, since the light of the backlight 5 can be effectively used for display, the brightness of the display can be remarkably improved as compared with the related art.

Further, according to the configuration of the liquid crystal display device of the present embodiment, since the reflective polarizing plate 21 is provided on the outer surface side of the lower polarizing plate 20, of the light emitted from the backlight 5, The component that is not parallel to the transmission axis of the polarizing plate 21 is reflected by the reflective polarizing plate 21 and returned to the backlight 5 side.
While repeating reflection with the reflection plate 18, the polarization state changes and the reflection polarization plate 21 can be transmitted,
It becomes light that can be used for display. Therefore, in the liquid crystal display device of the present embodiment, since the lower polarizing plate 20 hardly absorbs light, the light of the backlight 5 can be more efficiently used for display, and the display brightness in the transmission mode can be improved. It is a liquid crystal display that is excellent in quality.

(Second Embodiment) In the present embodiment, since the overall configuration of the liquid crystal display device is the same as that of the first embodiment shown in FIG. 1, detailed description will be omitted. The difference between the liquid crystal display device of the present embodiment and the liquid crystal display device of the first embodiment is that a color filter 11 is formed immediately above the lower reflective polarizing layer 6. The point that a flattening film 7 for flattening the unevenness of the color filter 11 is provided, and only this portion will be described with reference to FIG. FIG. 2 is a diagram showing a partial cross-sectional structure of the liquid crystal display device of the present embodiment. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals.

In the liquid crystal display device of the present embodiment shown in FIG. 2, since the color filter 11 is provided on the lower reflective polarizing layer 6, color shift and parallax in the reflection mode can be reduced. This is because the color filter 11 is provided immediately above the lower reflective polarizing layer 6,
After transmitting through one dye layer (for example, R pixel), it is reflected by the lower reflective polarizing layer 6 and again transmits through the same dye layer.

(Electronic Equipment) Examples of electronic equipment provided with the liquid crystal display device of each of the above embodiments will be described.

FIG. 8A is a perspective view showing an example of a mobile phone. In this figure, reference numeral 1000 denotes a mobile phone main body, and reference numeral 1001 denotes a liquid crystal display unit using the above liquid crystal display device.

FIG. 8B is a perspective view showing an example of a wristwatch-type electronic device. In this figure, reference numeral 1100 indicates a watch main body, and reference numeral 1101 indicates a liquid crystal display unit using the above-described liquid crystal display device.

FIG. 8C is a perspective view showing an example of a portable information processing device such as a word processor or a personal computer. FIG.
In (c), reference numeral 1200 denotes an information processing device, and reference numeral 1 denotes
Reference numeral 202 denotes an input unit such as a keyboard, reference numeral 1204 denotes an information processing apparatus main body, and reference numeral 1206 denotes a liquid crystal display unit using the above-described liquid crystal display device.

Since the electronic apparatus shown in FIGS. 8A to 8C includes the liquid crystal display using the liquid crystal display of the above embodiment, it has a display capable of obtaining a bright display in the transmission mode. Electronic devices can be realized.

[0064]

EXAMPLES Hereinafter, the effects of the present invention will be clarified by examples, but the present invention is not limited to the following examples.

Example 1 As Example 1, a liquid crystal display having the structure shown in FIG. 1 was manufactured. Each of the liquid crystal display devices was a passive matrix transflective color liquid crystal display device having a dot number of 160 dots × 120 dots and a dot pitch of 0.24 mm. In the liquid crystal display device of Example 1, the lower reflective polarizing layer 6 was formed by forming a slit in an aluminum thin film having the configuration shown in FIG. The thickness of the lower reflective polarizing layer 6 was 300 nm, the pitch of the slit was 150 nm, and the width of the slit was 75 nm. In addition, the lower reflective polarizing layer 6 has a thickness of 0.068 mm × 0.
022 mm opening (portion without lower reflective polarizing layer 6)
And formed on the diagonal of the pixel.

(Comparative Example 1) Next, as Comparative Example 1, FIG.
The liquid crystal display device having the conventional configuration shown in FIG. This liquid crystal display device also has a dot count of 160 dots × 120 dots and a dot pitch of 0.2 as in the liquid crystal display device of the first embodiment.
A 4 mm passive matrix type transflective color liquid crystal display device was used.

(Evaluation) With respect to the liquid crystal display devices of Example 1 and Comparative Example 1, the transmittance and the reflectance corresponding to the display brightness in the transmission mode and the reflection mode were measured. Further, the contrast in each of the transmission mode and the reflection mode was also measured. Table 1 shows the measurement results. Table 1
As shown in the figure, compared to the liquid crystal display device of Comparative Example 1, the liquid crystal display device of Example 1 having the configuration of the present invention has a transmittance of 3%.
It was confirmed that it improved more than twice. Also, the contrast at the time of transmission was doubled, and it was confirmed that the contrast was greatly improved. This is because the liquid crystal display device of the first embodiment can efficiently use the light of the backlight 5 for display. On the other hand, the reflectance of the liquid crystal display device of Example 1 was 30%, which was equivalent to that of the liquid crystal display device of Comparative Example 1, but the contrast in the reflection mode was significantly improved. This improvement in contrast is due to the fact that the brightness of the bright display is the same, but the dark display is darker.

[0068]

[Table 1]

[0069]

As described above in detail, the liquid crystal display device of the present invention is a transflective liquid crystal display device which is used while switching between the transmission mode and the reflection mode. Since the polarizing layer is provided and the lower polarizing layer is provided below the lower reflective polarizing layer, in the transmission mode, the use efficiency of light emitted from the illumination device is improved to realize a bright display. In the reflection mode, the dark display can be made darker and the contrast can be improved.

Next, the electronic apparatus according to the present invention is provided with the liquid crystal display device according to the present invention, so that an extremely bright display can be obtained in the transmission mode, and the electronic apparatus has a display unit with excellent contrast. Equipment can be realized.

[Brief description of the drawings]

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

FIG. 2 is a partial cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention.

FIGS. 3A and 3B are explanatory diagrams for explaining the operation principle of the liquid crystal display device of the present invention. FIG. 3A shows a transmission mode, and FIG. 3B shows a reflection mode. .

4A and 4B are explanatory diagrams for explaining the operation principle of the liquid crystal display device having the configuration shown in FIG. 10; FIG. 4A shows a state of a transmission mode, and FIG. Is shown.

FIG. 5 is an explanatory diagram for explaining the operation principle of another configuration of the present invention.

FIG. 6 is a perspective view showing an example of a lower reflective polarizing layer of the liquid crystal display device of the present invention.

FIG. 7 is a perspective view illustrating an example of a lower reflective polarizing layer of the liquid crystal display device of the present invention.

FIGS. 8A to 8C are perspective views showing an example of the electronic apparatus of the present invention.

FIG. 9 is a partial cross-sectional view showing an example of a liquid crystal display device having a conventional configuration.

FIG. 10 is a partial cross-sectional view showing another example of a liquid crystal display device having a conventional configuration.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal display device 2 lower substrate 3 upper substrate 4 liquid crystal 5 backlight (illumination device) 6 lower reflective polarizing layer 11 color filter 13 upper polarizing plate (upper polarizing layer) 20 lower polarizing plate (lower polarizing layer)

Continued on the front page F term (reference) 2H048 FA01 FA05 FA24 GA01 GA04 GA30 GA33 2H049 BA02 BA07 BA45 BB03 BB63 BC22 2H091 FA02Y FA08X FA08Z FA14Z FA41Z FB08 HA10 KA10 LA16 LA17

Claims (13)

[Claims] 1. A liquid crystal is sandwiched between an upper substrate and a lower substrate facing each other, an upper polarizing layer and a lower reflective polarizing layer are provided above and below the liquid crystal, and an illuminating device is provided on an outer surface side of the lower substrate. A transflective liquid crystal display device that performs display by switching between a transmission mode and a reflection mode, wherein the lower reflection polarization layer is partially provided on an inner surface side of the lower substrate; A liquid crystal display device, wherein a lower polarizing layer is provided on the lower side of the liquid crystal display. 2. The liquid crystal display device according to claim 1, further comprising a reflection polarizing plate having a transmission axis substantially parallel to a transmission axis of the lower polarizing layer, on an outer surface side of the lower polarizing layer. 3. The liquid crystal according to claim 2, wherein an angle formed between a transmission axis of the lower polarizing layer and a transmission axis of the reflective polarizing plate is in a range of −30 ° or more and 30 ° or less. Display device. 4. The liquid crystal display device according to claim 1, wherein said lower polarizing layer is provided on an outer surface side of said lower substrate. 5. The light-emitting device according to claim 1, wherein a scattering layer for scattering light reflected by the lower reflective polarizing layer is provided above the lower reflective polarizing layer. 3. The liquid crystal display device according to 1. 6. The liquid crystal display device according to claim 1, wherein said upper polarizing layer is provided on an inner surface side of said upper substrate. 7. The liquid crystal display according to claim 1, wherein a transmission axis of the lower reflective polarizing layer and a transmission axis of the lower polarizing layer are substantially orthogonal to each other. apparatus. 8. The method according to claim 1, wherein an angle formed between a transmission axis of the lower reflective polarizing layer and a transmission axis of the lower polarizing layer is in a range of 60 ° to 120 °. 2. The liquid crystal display device according to claim 1. 9. The liquid crystal display device according to claim 1, wherein a color filter is provided on an inner surface side of the upper substrate or the lower substrate. 10. The liquid crystal display device according to claim 1, wherein the lower reflective polarizing layer has a structure in which a dielectric interference film having a prism shape is laminated. 11. The liquid crystal according to claim 1, wherein the lower reflective polarizing layer has a configuration in which a plurality of fine slit-shaped openings are provided in a metal reflective film. Display device. 12. The pitch of the slit-shaped openings is:
The liquid crystal display device according to claim 11, wherein the range is 30 nm to 300 nm. 13. An electronic apparatus comprising the liquid crystal display device according to claim 1. Description: