JP2002303863A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying a picture of favorable visibility without dependence of use environment, and reducing power consumption. SOLUTION: The liquid crystal display device 1 is provided with 1st and 2nd substrates faced to each other, a plurality of 1st pixel electrodes 115a arranged on a 1st area in the surface of the 1st substrate faced to the 2nd substrate, a plurality of 2nd electrodes 115b arranged on a 2nd area in the surface of the 1st substrate faced to the 2nd substrate, a 1st common electrode supported on the 2nd substrate and faced to a plurality the 1st pixel electrodes, and a 2nd common electrode supported on the 2nd substrate and faced to a plurality of the 1st pixel electrodes, and a liquid crystal layer lying between a plurality of the 1st pixel electrodes and the 1st common electrode and between a plurality of the 2nd pixel electrodes and the 2nd common electrode, and is characterized in that the 1st display area 51 corresponding to the 1st area is able to display a picture by a light reflecting method, and the display area 52 corresponding to the 2nd area is able to display a picture by a light transmitting method.

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 capable of displaying an image by a light reflection method and a light transmission method.

[0002]

2. Description of the Related Art Conventionally, a display device of a portable device such as a mobile phone or a pager (registered trademark) has only been required to be able to display simple characters such as numbers and characters. However, with the rapid development of IT technology in recent years, even in the field of portable devices, particularly portable information terminals, practical use of small, light, thin, and low power consumption display devices capable of displaying high-definition color images. Is desired.

As a display device satisfying this demand, for example, a reflection type liquid crystal display device is considered to be promising, and has already begun to be put to practical use in some applications. The reflective liquid crystal display device can display an easy-to-view image when used outdoors during the day. However, since the reflection type liquid crystal display device has no light source, an image displayed in the dark can hardly be visually recognized. That is, the reflection type liquid crystal display device has a limitation in use environment.

As a countermeasure, a front light technology has been proposed. In the front light technology, the illuminance of external light is supplemented by covering the display surface of a reflective liquid crystal display device with a transparent surface light source. Although this technique does not require a change in the internal structure of the liquid crystal display device, the quality of a high-definition image deteriorates due to a decrease in the amount of reflected light, blurring of the image, an increase in the sense of depth, and the like.

On the other hand, Japanese Patent Application Laid-Open No. H11-316382 discloses
Japanese Patent Application Laid-Open Publication No. H11-139,897 discloses a liquid crystal display device that displays an image by a combination of light reflection and light transmission. This liquid crystal display device
Each pixel electrode is composed of a combination of a light reflecting conductive film and a light transmitting conductive film. In such a liquid crystal display device, an image is displayed by a light reflection method in a high illumination environment, and a backlight is turned on in a low illumination environment to perform image display by a light reflection method and a light transmission method.

[0006]

The above-mentioned liquid crystal display device of the combined use of light reflection and light transmission can display an image with good visibility without depending on the illuminance of external light. However, since the light-reflective conductive film and the light-transmitting conductive film are formed by independent processes, the yield is lowered and the manufacturing cost is increased. Further, in the above liquid crystal display device, it is necessary to overlap the light-reflective conductive film and the light-transmitting conductive film. For this reason, the reflectance is greatly reduced due to the overlapping of the conductive films, and it is difficult to obtain a bright image. Further, although the power consumption of the above-described liquid crystal display device using both light reflection and light transmission is reduced as compared with the liquid crystal display device using the light transmission method, the power consumption is not always sufficiently reduced.

Accordingly, an object of the present invention is to provide a liquid crystal display device capable of displaying an image with good visibility without depending on the use environment and further reducing power consumption. .

[0008]

According to a first aspect of the present invention, a first and a second substrate facing each other and a first area in a plane of the first substrate facing the second substrate are provided. A plurality of first pixel electrodes arranged, a plurality of second pixel electrodes arranged on a second area different from the first area in a surface of the first substrate facing the second substrate, and Second
A first common electrode supported by the substrate and opposed to the plurality of first pixel electrodes; a second common electrode supported by the second substrate and opposed to the plurality of first pixel electrodes; A liquid crystal layer interposed between a pixel electrode and the first common electrode and between the plurality of second pixel electrodes and the second common electrode, and a first display area corresponding to the first area is provided. A liquid crystal display device is provided, wherein an image is displayed by a light reflection method, and an image can be displayed by a light transmission method in a second display area corresponding to the second area.

According to a second aspect of the present invention, first and second substrates facing each other and a plurality of first substrates arranged on a first area in a surface of the first substrate facing the second substrate. A pixel electrode, a plurality of second pixel electrodes arranged on a second area different from the first area in a surface of the first substrate facing the second substrate, and supported by the second substrate. And a first common electrode facing the plurality of first pixel electrodes;
A second common electrode supported by the second substrate and opposed to the plurality of first pixel electrodes, between the plurality of first pixel electrodes and the first common electrode, and between the plurality of second pixel electrodes; A liquid crystal layer interposed between the first pixel electrode and a second common electrode, wherein each of the plurality of first pixel electrodes is a reflective conductive film;
A liquid crystal display device is provided, wherein each of the plurality of second pixel electrodes is a reflective conductive film provided with at least one opening.

According to a third aspect of the present invention, a first and a second substrate facing each other and a plurality of first and second substrates arranged on a first area in a surface of the first substrate facing the second substrate. A pixel electrode, a reflective film interposed between the plurality of first pixel electrodes and the first substrate, and different from the first area in a surface of the first substrate facing the second substrate; A plurality of second pixel electrodes arranged on a second area; and a first pixel electrode supported by the second substrate and opposed to the plurality of first pixel electrodes.
A common electrode; a second common electrode supported by the second substrate and opposed to the plurality of first pixel electrodes;
Between the pixel electrode and the first common electrode and between the plurality of second electrodes;
A liquid crystal layer interposed between a pixel electrode and the second common electrode, wherein the plurality of first pixel electrodes and the plurality of second
A liquid crystal display device is provided, wherein each of the pixel electrodes is a transparent conductive film.

The light reflection method refers to a display method using external light incident from the display surface or light from the front light without using a light source disposed on the non-display surface side. On the other hand, the light transmission method refers to a display method using light from a light source disposed on the non-display surface side, in which the usage ratio of external light or front light is smaller than that of the light reflection method. That is, the light transmission method is a method in which display is performed using only the light source on the non-display surface side, and light from the light source on the non-display surface side and light from the light source (external light and / or front light) on the display surface side. And a method of performing display using light (combined use of light reflection and transmission).

In the liquid crystal display device according to the first and third aspects of the present invention, an image can be displayed by the light reflection method in the first display area corresponding to the first area, and the second display area corresponding to the second area can be displayed. An image can be displayed by a light transmission method in two display areas.

In the liquid crystal display devices according to the first and second aspects of the present invention, an image can be displayed by the light reflection method in the first display area corresponding to the first area, and the first display area corresponding to the second area can be displayed. An image can be displayed in the two display areas by the light reflection method and the light transmission method.

In a first aspect of the present invention, a plurality of first
Each of the pixel electrodes may be a light-reflective conductive film, and each of the plurality of second pixel electrodes may be a light-reflective conductive film provided with at least one opening. In this case, the material of the plurality of first pixel electrodes and the material of the plurality of second pixel electrodes may be the same. Further, the material of the first common electrode and the material of the second common electrode may be the same.

In a first aspect of the present invention, a plurality of first
Each of the pixel electrode and the plurality of second pixel electrodes may be a transparent conductive film. In this case, the liquid crystal display device may further include a reflective layer between each of the plurality of first pixel electrodes and the first substrate.

In the first to third aspects of the present invention, the first common electrode and the second common electrode may be electrically connected to each other.

The liquid crystal display device according to the first to third aspects of the present invention further includes a surface light source device for irradiating light toward the liquid crystal layer from the back side of the first substrate facing the second substrate. May be. In this case, the surface light source device may be configured to selectively emit light to the second display area of the first display area corresponding to the first area and the second display area corresponding to the second area. .

[0018]

Embodiments of the present invention will be described below with reference to the drawings. In each of the drawings, the same components are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1A is a sectional view schematically showing a liquid crystal display device according to a first embodiment of the present invention.
FIGS. 2B and 2C are enlarged cross-sectional views of a part of the liquid crystal display device shown in FIG. FIG. 2A is a plan view of the liquid crystal display device shown in FIG.
FIG. 2B is a plan view schematically showing an array substrate of the liquid crystal display device shown in FIG.

The liquid crystal display device 1 according to the first embodiment of the present invention is, for example, a VGA type liquid crystal display device having a diagonal size of 10 cm. In this liquid crystal display device 1,
The display area includes a reflection area 51 that performs display by a light reflection method,
It is composed of a reflection / transmission area 52 for performing display using a combination of light reflection and light transmission. The structure shown in FIG.
The structure shown in FIG. 1C corresponds to a part of the reflection area 51 of the liquid crystal display device 1 shown in FIG. 1A, and the structure shown in FIG. Corresponds to the department.

The liquid crystal display device 1 includes a liquid crystal cell 100
And a control circuit board 200 electrically connected to the liquid crystal cell 100 and a surface light source device 300 arranged at a position corresponding to the reflection / transmission area 52 of the liquid crystal cell 100 and irradiating the area 52 with light. It is configured. Liquid crystal cell 100
Includes an array substrate 110, a counter substrate 120, and a liquid crystal layer 130 held between the substrates 110 and 120 via an alignment film, and emits light on a surface facing the surface on the surface light source device 300 side. With the face. The liquid crystal cell 100 and the control circuit board 200 are formed by a TCP (tape) in which a driving IC is mounted on a flexible wiring board (flexible wiring board).
Carrier package) 700. TCP700 can be folded,
In the present embodiment, the control circuit board 200 is arranged on the side facing the light emitting surface of the liquid crystal cell 100 by utilizing such flexibility of the TCP 700. Also, the array substrate 110
And a 波長 wavelength plate 41 on each outer surface of the counter substrate 120.
The angle formed between the slow axis of the quarter-wave plate 410 and the transmission axis of the polarizing plate 510 is the slow axis of the quarter-wave plate 420 and the transmission axis of the polarizing plate 520. Is attached so that it is equal to the angle between

The array substrate 110 includes a light-transmitting substrate 111 such as glass, signal lines 112 arranged substantially in parallel and at equal intervals on the substrate 111, and scanning lines arranged substantially orthogonal to the signal lines 112. 114, an interlayer insulating film 113 interposed between the signal line 112 and the scanning line 114 to electrically insulate them, and a TFT (thin f n) disposed near the intersection of the signal line 112 and the scanning line 114, respectively.
ilm transformer) 150 and their TF
It is mainly composed of pixel electrodes 115a and 115b connected to T150. An alignment film 116 is provided on almost the entire surface of the array substrate 110 on which the pixel electrodes 115a and 115b are provided.

The pixel electrodes 115a, 1 on the array substrate 110
Reference numeral 15b is a conductive light reflection film made of, for example, Al. The pixel electrode 115a in the reflection region 51 is obtained by patterning a conductive light reflection film into a predetermined shape. In addition, the pixel electrode 115b in the reflection / transmission region 52 has one or more openings for transmitting incident light in the conductive light reflection film,
It is obtained by patterning into a predetermined shape. For example, the size of each of the pixel electrodes 115a and 115b is
.mu.m.times.120 .mu.m, and a circular opening having a diameter of 4 .mu.m is formed in each pixel electrode 115b of the reflection / transmission region 52 by one.
Five are arranged irregularly. Normally, when the area of the opening is set to about 5% or less with respect to the area of the pixel, the decrease in the area ratio of the conductive light reflecting film to the area of the pixel is substantially negligible.

The opposing substrate 120 mainly includes a light-transmitting insulating substrate 121 such as glass, a light-shielding layer 122, a coloring layer (color filter layer) 123, an opposing electrode 124, and an alignment film 125. . In the present embodiment, the counter electrode 124 is shared between the reflection region 51 and the reflection / transmission region 52. However, the counter electrode 124 may be divided between the regions 51 and 52.

The alignment film 116 of the array substrate 110 and the alignment film 125 of the opposing substrate 120 are, for example, liquid crystal layers 1
The liquid crystal molecules in the liquid crystal 30 are aligned so as to be twisted at an angle of about 70 °. The orientation direction of the liquid crystal layer 130 on the display surface side and the slow axis 421 of the quarter-wave plate 420 form an angle of, for example, 45 °.

The array substrate 110 and the counter substrate 120 are
It is integrated by a sealing material (not shown) arranged in a frame shape on the periphery between the substrates to form a hollow cell,
A liquid crystal material is sealed in this cell to constitute a liquid crystal cell 100. Here, a nematic liquid crystal having a refractive index anisotropy Δn of about 0.08 and a relative dielectric constant ε / ε _{0 of about} +8 is used as the liquid crystal material.

As described above, in the liquid crystal display device 1 according to the present embodiment, the display area includes a plurality of display pixels in which the liquid crystal layer 130 is sandwiched between the pixel electrode 115a and the counter electrode 124 in a matrix. It is composed of an arrayed reflective area 51 and a reflective / transmissive area 52 in which a plurality of display pixels having a liquid crystal layer 130 sandwiched between a pixel electrode 115b and a counter electrode 124 are arranged in a matrix. That is, in the present embodiment, the display area disposed inside the sealing material includes the reflection area 51 having a plurality of display pixels for performing display in the light reflection scheme and the light transmission scheme (here, a combination of light reflection and transmission). System) and a reflective / transmissive region 52 having a plurality of display pixels.

The display pixels of the reflection area 51 and the reflection / transmission area 52 can be formed in the same process.
Moreover, the same layer structure can be obtained.

Next, an image display method using the above-described liquid crystal display device 1 will be described.

FIGS. 3A and 3B are perspective views schematically showing a dark display state, and FIGS. 4A and 4B are perspective views schematically showing a bright display state. FIGS. 3A and 4A show a part of the reflection area 51, and show an image display method by a light reflection method. FIG. 3 (b)
And FIG. 4B illustrates a part of the reflection / transmission area.
The image display method by the light transmission system is shown.

As shown in FIGS. 3A and 4A,
In the reflection area 51, the polarizing plate 520, the 波長 wavelength plate 42
0, the liquid crystal layer 130, and the pixel electrode 115a are combined to form a normally reflective white light display. On the other hand, in the reflection / transmission region 52, as shown in FIGS. 3B and 4B, normally white display by the same light reflection method as that of the reflection region 51 is possible, and in addition, a polarizing plate 52 is provided.
A normally white display by a light transmission method in which the 0, 1/4 wavelength plate 420, the liquid crystal layer 130, the 1/4 wavelength plate 410, and the polarizing plate 510 are combined is possible.

More specifically, the pixel electrodes 115a, 1
When a voltage equal to or higher than the threshold voltage is applied between the electrode 15b and the counter electrode 124, the liquid crystal molecules are aligned so that the molecular long axis is perpendicular to both substrate surfaces except near the electrode surface. Therefore, the light that has entered the liquid crystal layer 130 exits the liquid crystal layer 130 without changing its polarization state. Therefore, in the reflection region 51, as shown in FIG. 3A, the light 600 from outside becomes linearly polarized light by transmitting through the polarizing plate 520, and this linearly polarized light is transmitted through the quarter wave plate 420. It becomes circularly polarized light. This circularly polarized light is applied to the liquid crystal layer 1
Since no change occurs in the polarization state at 30, the counterclockwise circularly polarized light that reaches the pixel electrode 115a having light reflectivity becomes
By being reflected, the light becomes reverse circularly polarized light. The right-handed circularly polarized light passes through the liquid crystal layer 130 and is further divided by １ ／.
By transmitting the light through the wavelength plate 420, the vibration direction becomes linearly polarized light perpendicular to the transmission axis 521 of the polarizing plate 520. This linearly polarized light cannot pass through the polarizing plate 520. In the reflection area 51 and the reflection / transmission area 52, dark display using the light reflection method is performed in this manner.

The pixel electrode 115b and the counter electrode 124
3B, light 310 from the surface light source device 300 passes through the surface light source side polarizing plate 510 in the reflection / transmission region 52 as shown in FIG. , Becomes linearly polarized light, and this linearly polarized light becomes circularly polarized light by transmitting through the 波長 wavelength plate 410. Part of the circularly polarized light passes through the aperture of the pixel electrode 115b and passes through the liquid crystal layer 130 without changing the polarization state. The circularly polarized light transmitted through the liquid crystal layer 130 transmits through the quarter wave plate 420 to generate an optical path difference of １ ／ wavelength between the two polarized light components. As a result, the vibration direction is changed to the transmission axis 521 of the polarizing plate 520. And perpendicular linearly polarized light. This linearly polarized light cannot pass through the polarizing plate 520. Reflection / transmission area 5
In 2, the dark display using the light transmission method is performed in this manner.

On the other hand, when no voltage is applied, the liquid crystal layer 1
The liquid crystal molecules in 30 are twisted. Therefore, the liquid crystal layer 130 exhibits birefringence and functions similarly to a quarter-wave plate. Therefore, in the reflection region 51, as shown in FIG.
The light enters the liquid crystal layer 130 as circularly polarized light via the wavelength plate 420 and exits the liquid crystal layer 130 as linearly polarized light. This linearly polarized light is reflected by the pixel electrode 115a,
By transmitting 0 again, the light becomes circularly polarized light. The circularly polarized light is transmitted through the quarter-wave plate 420, and becomes a linearly polarized light whose vibration direction is parallel to the transmission axis 521 of the polarizing plate 520. This linearly polarized light can pass through the polarizing plate 520. In the reflection area 51 and the reflection / transmission area 52, bright display using the light reflection method is performed in this manner.

When no voltage is applied, the reflection / transmission region 52
Then, as shown in FIG. 4B, light 310 from the surface light source device 300 is incident on the liquid crystal layer 130 as circularly polarized light via the polarizing plate 510 and the 波長 wavelength plate 410, and is linearly polarized light. Is emitted. The linearly polarized light becomes circularly polarized light by transmitting through the quarter-wave plate 420, and a part of the circularly polarized light can be transmitted through the polarizing plate 520. In the reflection / transmission area 52, bright display using the light transmission method is performed in this manner.

As described above, the display operation can be performed in the same display mode in the light reflection region and the light transmission region, here, the normally white display mode. Therefore, the polarity of light and dark display with respect to the signal voltage of the image signal can be matched between the light reflection region and the light transmission region.

As described above, in this embodiment, the display area is composed of the reflection area 51 and the reflection / transmission area 52. Therefore, light from the surface light source device 300 is reflected and
It can be used only in the transmission region 52. Therefore, power consumption can be further reduced.

When the display area is composed of the reflection area 51 and the reflection / transmission area 52, it is sometimes difficult to visually recognize the image displayed in the reflection area 51 if the surrounding area is dark.
However, not all information that can be displayed by the liquid crystal display device 1 is frequently used in a dark place. Therefore, if the information that is frequently used in a dark place is displayed in the reflection / transmission area 52 and the information that is not frequently used in the dark place is displayed in the reflection area 51, the brightness of the surrounding environment can be changed. Even if the user does not feel inconvenience, it is possible to display an image with good visibility regardless of the use environment.

In the present embodiment, the surface light source device 300
Is used only in the reflection / transmission region 52, the surface light source device 300 may be provided only in a position corresponding to the reflection / transmission region 52. Therefore, according to the present embodiment,
The weight of the liquid crystal display device 1 can be reduced.

Further, in this embodiment, the surface light source device 30
0 can be provided only at the position corresponding to the reflection / transmission region 52, so that the surface light source device 300 on the back side of the liquid crystal cell can be provided.
It is possible to arrange the control circuit board 200 in a portion where is not arranged, that is, in a portion corresponding to the reflection region 51. Therefore, in addition to achieving a reduction in the thickness of the entire device, the cost of the surface light source device 300 can be suppressed as compared with the case where the surface light source device 300 is provided so as to irradiate the entire surface of the liquid crystal cell.

In addition, in this embodiment, the reflection area 51 and the reflection / transmission area 52 have substantially the same layer configuration except for the presence or absence of the surface light source device 300. Therefore, it is possible to realize a liquid crystal display device capable of displaying an image by a light reflection method and a light transmission method without increasing the number of manufacturing processes, increasing the number of components, complicating the structure, and lowering the yield.

In the present embodiment, the area ratio between the reflection area 51 and the reflection / transmission area 52 is not particularly limited, and is appropriately set according to the application.

In the present embodiment, the number of the reflection areas 51 and the number of the reflection / transmission areas 52 included in the display area is not particularly limited. However, when the display region includes a plurality of reflection / transmission regions 52, it is desirable that the reflection region 51 is not interposed between the regions 52. In this case, the smaller surface light source device 3
0 can be used.

In the present embodiment, it is desirable that the display pixels included in the reflection / transmission region 52 be concentrated and not dispersed in the cell. For example, the entire periphery of the liquid crystal cell is constituted by light reflection type display pixels,
The vicinity of the center may be configured by a display pixel using both the light reflection and light transmission methods. In this case, a smaller surface light source device 30 can be used.

Further, in the present embodiment, FIG.
As shown in (b) and (c), the pixel electrodes 115a and 115
b and the source electrode of the TFT 150 were formed separately,
They can also be formed of the same material and at the same time. At the same time, the signal line 112 can be formed.

In the present embodiment, the angle formed between the transmission axis of the polarizing plate 520 and the slow axis of the quarter-wave plate 420;
The angle between the transmission axis of the polarizing plate 510 and the slow axis of the quarter-wave plate 410 is not particularly limited as long as they are equal to each other. For example, polarizing plates 510 and 520 and quarter-wave plates 410 and 4
20, the retardation axis 411 of the quarter-wave plate 410 forms an angle of 80 ° with the transmission axis 511 of the polarizing plate 510, and the retardation axis of the quarter-wave plate 420 with respect to the transmission axis 521 of the polarizing plate 520. The phase axis 411 forms an angle of 80 °.
The transmission axis 521 of the polarizing plate 510 may be parallel to the transmission axis 521 of the polarizing plate 510. In the present embodiment, the liquid crystal display device 1 is designed to perform a normally white display, but may be designed to perform a normally black display. Further, in the present embodiment, the 波長 wavelength plate 410 and the polarizing plate 510 are arranged on the entire outer surface of the array substrate 110, but they need not be arranged at positions corresponding to the reflection region 51.

In this embodiment, the １ ／ wavelength plate 41
Each of 0 and 420 has a single-layer structure.
A laminated structure in which a 波長 wavelength plate and a 波長 wavelength plate are laminated may be used. In the latter case, it is possible to prevent the refractive index anisotropy of the quarter-wave plates 410 and 420 from largely changing according to the wavelength.

Next, a portable device using the liquid crystal display device 1 will be described.

FIG. 5 is a plan view schematically showing an example of a portable device using the liquid crystal display device 1 according to the first embodiment of the present invention. A portable device is required to be able to view images and characters well regardless of the use environment.

The portable device 2 shown in FIG. 5 is a PDA (per
sonal data / digital assistant
Ants). The PDA 2 includes a display unit having the liquid crystal display device 1, a power button 21, and a surface light source device 300.
Backlight button 22 for manually performing ON / OFF operation of the terminal, a schedule button 23 for displaying a schedule book, and an address button 24 for displaying an address book
And a memo button 25 for displaying a memo pad.

The display section of the PDA 2 is composed of an information display screen 26 and an input operation screen 27. Information display screen 2
6 corresponds to the reflection / transmission area 52 of the liquid crystal display device 1, and the input operation screen 27 corresponds to the reflection area 51. The surface light source device 300 is disposed only at a position corresponding to the reflection / transmission region 52. Since the control circuit board 200 for driving the liquid crystal display device 1 is disposed at a position corresponding to the reflection area 51, the device can be made thinner and lighter.

As shown in FIG. 5, the information display screen 26 corresponding to the reflection / transmission area 52 displays, for example, information stored in a schedule, an address book, a memo pad, etc., a page break icon 26a, and the like. . In the input operation screen 27 corresponding to the reflection area 51, for example, information can be input with a pen 28, and input operation units such as a character input pad 27a and an input mode switching button 27b are displayed. Thus, in the PDA 2 shown in FIG. 5, information can be input via the input operation screen 27. Further, since the input operation unit is constituted by a display screen of the liquid crystal display device, it is possible to easily change the input operation unit by changing an image displayed on the input operation screen 27 according to information input by the user. Can be.

An example of the method of using the PDA 2 will be described. After turning on the power, the user determines whether to turn on or off the surface light source device 300. That is, when the surrounding brightness is insufficient, the surface light source device 300 is turned on by operating the backlight button 22. The backlight button 22 is used not only immediately after the power is turned on, but also when the PDA
2 can be operated at any time while in use.
When the surrounding brightness is sufficient, the surface light source device 300 can be turned off by operating the backlight button 22. Further, the power button 21 is turned off.
The surface light source device 300 may be turned off in conjunction with the F operation.

In general, light from the surface light source device 300 is not always needed to check the display content of the information display screen 26. Therefore, as described above, if the surface light source device 300 can be turned on / off when desired by the user, unnecessary power consumption can be reduced. Also,
Generally, an input operation screen 27 for performing pen input or the like
Is used less frequently than the information display screen 26 that displays information stored in the memory, received information, and the like. Therefore, if display by the light transmission method is possible on the information display screen 26, even if display by the light transmission method cannot be performed on the input operation screen 27, there are not many problems.

More specifically, when the PDA 2 is used in a bright state, the reflection area 51 and the reflection / transmission area 52 can be used even when the surface light source device 300 is off.
In both cases, the displayed image can be viewed well. In this case, the surface light source device 300 does not consume power.

In the case where the displayed image cannot be viewed satisfactorily only by external light, the surface light source device 300 can be turned on by pressing the backlight button 22 of the PDA 2. In this case, in the reflection / transmission area 52,
By using both the light reflection method and the light transmission method, an image with good visibility can be displayed.

Further, when the surroundings are dark such as at night, the visibility of an image displayed using only the light reflection method is significantly reduced. Therefore, in this case, the visibility of the image displayed on the information display screen 26 can be improved by operating the backlight button 22 to turn on the surface light source device 300.

As described above, according to the PDA 2 shown in FIG. 5, the user can display images and characters on the information display screen 26 without inconvenience regardless of the brightness of the surrounding environment, and Power consumption can be reduced.

FIG. 6 is a plan view schematically showing another example of a portable device using the liquid crystal display device according to the first embodiment of the present invention. The mobile device 3 shown in FIG. 6 is a mobile phone. This mobile phone 3 has a
It is desirable to be able to confirm the name and telephone number of the other party when making and receiving calls. In addition, some users use the mobile phone 3 as a clock, and it is desirable that the current time can be confirmed regardless of the surrounding brightness.

The portable telephone 3 has a display unit having the liquid crystal display device 1, a telephone number button 31, and a call button 32.
, An end button 33, and a backlight button 34 for manually controlling turning on / off of the surface light source device. In this embodiment, the backlight button 34 is provided on the side of the mobile phone 3 so that the button 34 can be easily found even by groping.

The liquid crystal display device 1 of the portable telephone 3 has, for example, current time and incoming information (name, telephone number, e-mai).
1) and a reflection / transmission area 52 for displaying a call time, a call charge, the contents of mail, and the like.
1 and 1. That is, regardless of the brightness of the surrounding environment, the minimum information that the user desires to view is displayed in the reflection / transmission area 52 so that the necessary display image can be visually recognized even if the use environment is restricted. it can.

An example of how to use the portable telephone 3 will be described. After the power is turned on, the surface light source device 3 is determined by the user.
When 00 is turned on, the reflection / light transmission region 52 of the liquid crystal display device 3 performs display by the light reflection / light transmission system, and the reflection region 51 performs display by the light reflection system.

When the backlight button 34 is manually operated at any time and the surface light source device 300 is turned off at the discretion of the user, it is possible to display only the light reflection method in the reflection / transmission area.

For example, it is effective to operate the backlight button 34 to turn off the surface light source device when the surroundings are sufficiently bright and a good display can be made only with external light. In this way, the mobile phone 3 can be used with the minimum necessary power consumption, and the mobile phone can be used for a longer time even with a battery having a predetermined capacity.

In a case where it is difficult to visually recognize an image or a character displayed by the light reflection method because the surroundings are dark, it is desirable to confirm minimum information such as a call arrival, for example, information such as a caller's name and a telephone number. At this time, the surface light source device 30 that irradiates the reflection / transmission area 52 by operating the backlight button 34
By setting 0 to the lighting state, it is possible to visually recognize the image displayed by the light transmission method. Then, after confirming the display content, if it is not necessary to confirm the display unit, for example, during a call, the surface light source device 300 can be turned off and the call can be continued.

As described above, in a portable device,
Even when the surroundings are dark, only the part where display confirmation is desired is displayed by using the light reflection / light transmission method together.
0 may be arranged at a position where only the reflection / transmission region 52 is illuminated, and the weight of the device can be reduced as compared with the case where it is arranged to illuminate the entire display region.

Further, it is possible to arrange a control circuit board and the like on a portion of the back surface of the liquid crystal cell where the surface light source device is not arranged, thereby achieving a reduction in thickness of the entire device.

The lighting / extinguishing of the surface light source device 300 is
Since the determination can be performed by the user, wasteful power consumption can be suppressed.

As described above, it is possible to confirm a display image which is desired to be visually recognized without being restricted by the use environment, and to use a display device which achieves low power consumption, thereby realizing miniaturization required for a portable terminal. It is possible to realize weight reduction, thickness reduction, and low power consumption.

In the above-described embodiment, the liquid crystal display device having the reflection area for displaying by the light reflection method and the reflection and transmission area for displaying by the combined light reflection and transmission method has been described. The present invention can be applied to all types of liquid crystal display devices that perform display by a light transmission method and a light transmission method.

FIG. 7A is a sectional view schematically showing a part of a reflection region of a liquid crystal display device according to a second embodiment of the present invention, and FIG. 7B is a sectional view showing the second embodiment of the present invention. FIG. 3 is a cross-sectional view schematically illustrating a part of a transmission region of the liquid crystal display device according to the embodiment. The liquid crystal display device according to the second embodiment is according to the first embodiment except that the display region is configured by a reflection region performing display by a light reflection system and a transmission region performing display by a light transmission system. It has almost the same structure as the liquid crystal display device. That is, the second embodiment is almost the same as the first embodiment except that the reflection / transmission region is a transmission region.

As shown in FIG. 7A, in the reflection region of the liquid crystal display device according to the present embodiment, the drain electrode 117 made of the same metal as the signal line 112 is replaced with the pixel electrode 115 made of a transparent conductive material such as ITO. And functions as a light reflecting plate. On the other hand, as shown in FIG. 7B, in the transmission region, the drain electrode 117 is connected to the pixel electrode 1.
It is configured such that light from the surface light source device 300 is incident on the liquid crystal layer 130 without extending below the portion 15. With such a liquid crystal display device, substantially the same effects as those described in the first embodiment can be obtained. Note that the liquid crystal display device according to the present embodiment may further include a front light.

[0073]

As described above, according to the present invention, a first display area including a plurality of pixels and capable of displaying an image by a light reflection method, and an image including a plurality of pixels and capable of displaying an image by a light transmission method. A display area is constituted by the second display area. Therefore, light from the surface light source device can be used only in the second display area. Therefore, power consumption can be further reduced. That is, according to the present invention, there is provided a liquid crystal display device which can display an image with good visibility without depending on the illuminance of external light and can further reduce power consumption.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view schematically showing a liquid crystal display device according to a first embodiment of the present invention, and FIGS. 1B and 1C each show a part of the liquid crystal display device shown in FIG. FIG.

2A is a plan view of the liquid crystal display device shown in FIG. 1A, and FIG. 2B is a plan view schematically showing an array substrate of the liquid crystal display device shown in FIG.

FIGS. 3A and 3B are perspective views schematically showing a dark display state.

FIGS. 4A and 4B are perspective views schematically showing a bright display state.

FIG. 5 is a plan view schematically showing an example of a portable device using the liquid crystal display device according to the first embodiment of the present invention.

FIG. 6 is a plan view schematically showing another example of a portable device using the liquid crystal display device according to the first embodiment of the present invention.

FIG. 7A is a sectional view schematically showing a part of a reflection region of a liquid crystal display device according to a second embodiment of the present invention, and FIG.
FIG. 4 is a cross-sectional view schematically showing a part of a transmission region of a liquid crystal display device according to a second embodiment of the present invention.

[Explanation of symbols]

1: liquid crystal display device; 2: PDA; 3: mobile phone;
21 to 25 ... buttons; 26 ... information display screen; 27 ...
Input operation screen; 27a: Character input pad; 27b: Input mode switching button; 28: Pen; 31 to 34: Button; 51: Reflection area; 52: Reflection / transmission area;
0: liquid crystal cell; 110: array substrate; 111: light transmitting substrate; 112: signal line; 113: interlayer insulating film;
114: scanning line; 115, 115a, 115b: pixel electrode; 116: alignment film; 117: drain electrode;
0: counter substrate; 121: light-transmitting insulating substrate; 122:
123: colored layer; 124: counter electrode; 12
5: alignment film; 130: liquid crystal layer; 150: TFT;
00: control circuit board; 300: surface light source device; 310
... light; 410, 420 ... 1/4 wavelength plate; 421 ... slow axis; 510, 520 ... polarizing plate; 521 ... transmission axis;
00: light; 700: TCP

Continuing from the front page (72) Inventor Akimasa Toyama 50 Kamiyube, Yobe-ku, Himeji-shi, Hyogo F-term in Himeji Plant, Toshiba Corporation (reference) 2H091 FA08X FA08Z FA11X FA11Z FA14Z FA41X FA41Z GA02 GA13 LA30 5C094 AA01 AA22 BA03 BA43 CA19 DA20 EA04 EA07

Claims (6)

[Claims] A first and a second substrate facing each other; a plurality of first pixel electrodes arranged on a first area in a surface of the first substrate facing the second substrate; and the first substrate. A plurality of second pixel electrodes arranged on a second area different from the first area in a plane opposed to the second substrate, and the plurality of first pixel electrodes supported by the second substrate A first common electrode opposed to the first substrate, a second common electrode supported by the second substrate and opposed to the plurality of first pixel electrodes, and between the plurality of first pixel electrodes and the first common electrode. A liquid crystal layer interposed between the plurality of second pixel electrodes and the second common electrode; a first display area corresponding to the first area displays an image by a light reflection method; The second display area corresponding to the area can display an image by a light transmission method. A liquid crystal display device characterized by the above-mentioned. 2. The liquid crystal display device according to claim 1, wherein the second display area can display an image by a light transmission method and can display an image by a light reflection method. 3. Each of the plurality of first pixel electrodes is a light-reflective conductive film, and each of the plurality of second pixel electrodes is a light-reflective conductive film provided with at least one opening. The liquid crystal display device according to claim 1, wherein: 4. The material of the plurality of first pixel electrodes and the material of the plurality of second pixel electrodes are the same, and the material of the first common electrode and the material of the second common electrode are the same. The liquid crystal display device according to claim 3, wherein: 5. A surface light source device for irradiating light toward the liquid crystal layer from a back surface of a surface of the first substrate facing the second substrate, wherein the surface light source device includes the first and second light sources. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is configured to selectively irradiate the light to the second display region of the two display regions. 6. A first and second substrate facing each other, a plurality of first pixel electrodes arranged on a first area in a surface of the first substrate facing the second substrate, and the first substrate. A plurality of second pixel electrodes arranged on a second area different from the first area in a plane opposed to the second substrate, and the plurality of first pixel electrodes supported by the second substrate A first common electrode opposed to the first substrate, a second common electrode supported by the second substrate and opposed to the plurality of first pixel electrodes, and between the plurality of first pixel electrodes and the first common electrode. A liquid crystal layer interposed between the plurality of second pixel electrodes and the second common electrode, wherein each of the plurality of first pixel electrodes is a reflective conductive film; Each at least one
A liquid crystal display device comprising a reflective conductive film provided with two openings.