JP2003228040A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that since an aperture rate becomes small when a display of high resolution which is three times that of a conventional one is made with the same screen size, power consumption becomes large when a panel having the same lightness as before is used. <P>SOLUTION: The size of each pixel of a rough display part is made 9 times as large as each pixel of a high-definition display part and then such individual display that the rough display part displays video information and the high- definition display part displays character information can be made; and the high-definition display part can display information 9 times as much as before. Video information can be displayed on a rather large picture by integrally displaying the same video information as that on the rough display part at the high-definition display part. In this case, the video signal to be inputted to one pixel of the rough display part is inputted to 9 pixels of the high- definition display part. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device used for mobile phones, portable information terminals and the like, and more particularly to a field sequential color liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, with the remarkable development of communication technology, and in particular, the transfer of high-speed and large-capacity data, the display devices used for mobile phones or personal digital assistants can display higher-definition images. It has come to be requested.
Since the liquid crystal display device of the field sequential color display system does not need a color filter, it has advantages such as high brightness and high resolution.

In Japanese Patent Laid-Open No. 11-14988, an OC
A field sequential color display type liquid crystal display using a B-mode liquid crystal panel is disclosed.
FIG. 5 is a conceptual diagram of a liquid crystal panel used in a field sequential color liquid crystal display disclosed in Japanese Patent Laid-Open No. 11-14988. Cell gap 7 μm
A phase compensation plate 53 is provided on the front surface of the following bend alignment liquid crystal cell 51.
A display panel 50 in which the cells and the phase compensator are sandwiched by orthogonal polarizers 55, a TFT active matrix for driving each pixel by partitioning the display panel into pixels arranged in a matrix, and a display panel Is a liquid crystal display provided with a surface light source 57 for sequentially irradiating three color lights of R, G, and B on the back surface of.

That is, since color images are displayed by mixing RGB colors over time, color filter layers for three RGB colors are not required. Therefore, when trying to obtain the same resolution with the same size, the area of one pixel is tripled, and a bright panel can be obtained. On the contrary, when the pixel size is the same, the resolution can be increased three times.

[0005]

However, in the case of the liquid crystal display device as described above, the following problems remain. That is, (1) In order to display a three times higher resolution with the same screen size, the pixel size becomes smaller and the aperture ratio becomes smaller. If so, power consumption will increase.

(2) In a normal active matrix type liquid crystal display device using a color filter, in order to reduce power consumption, the transmittance of the color filter may be lowered, but as a result, the color reproducibility is lowered. Resulting in.

[0007]

In order to solve the above problems, the liquid crystal display device of the present application has the following configuration. That is, (1) a liquid crystal panel, a light source for irradiating the liquid crystal panel, and a driving unit for switching the color of the light source in time sequential order and controlling the transmission or reflection state of the liquid crystal panel in synchronization therewith, In the liquid crystal display device that performs color display with such an additive color mixture, the liquid crystal panel includes a display portion including a plurality of display regions including a rough display portion and a high definition display portion.

(2) The size of one pixel of the rough display portion is set to correspond to the size of a plurality of pixels of the high definition display portion.

(3) The size of one pixel of the rough display portion is substantially equivalent to the size of the nth power of 9 pixels of the high definition display portion (n is an integer of 1 or more).

(4) A mode in which a plurality of displays including a rough display section and a high-definition display section are displayed, and a mode in which the rough display section and the high-definition display section are integrated to display one image. It is configured to include.

(5) A mode in which a plurality of displays including a rough display section and a high-definition display section are displayed, and a mode in which the rough display section and the high-definition display section are integrated to display one image. It is configured to include a switching means for freely switching between.

(6) In a mode in which at least the rough display section and the high-definition display section integrally display one image, the brightness of the rough display section and the brightness of the high-definition display section are substantially the same. It was configured to be bright.

(7) The brightness of the display unit is configured to be substantially the same as the brightness of the high definition display unit.

(8) The driving means is constructed so that the brightness of the rough display portion and the brightness of the high definition display portion are substantially the same.

(9) The brightness distribution of the light source is configured such that the brightness of the rough display portion and the brightness of the high definition display portion are substantially the same.

(10) The light source is composed of LED elements.

(11) The liquid crystal panel has an OCB mode in which a phase compensating plate is arranged in front of the bend alignment liquid crystal.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A first embodiment of the present invention will be described with reference to the drawings.

FIG. 2A is an enlarged sectional view showing the structure of the liquid crystal display device according to the first embodiment of the present invention. Figure 2
FIG. 2B is an enlarged plan view of a pixel portion showing the configuration of the liquid crystal display device according to the first embodiment of the present invention.

In FIG. 2, 1 is a liquid crystal panel, 2 is a backlight, 3 is an array substrate, 4 is a counter substrate, 5 is a liquid crystal layer, 6 is a counter electrode, 7 is a pixel electrode, and 8 is connected to the pixel electrode 7. A video signal line for supplying a video signal, 9 is a scanning signal line,
10 is a semiconductor switching element, 11 is a first insulating layer, 1
2 is a second insulating layer, 13 is a black matrix layer, 14
a is an alignment film formed on the inner surface of the array substrate 3, 14b is an alignment film formed on the inner surface of the counter substrate 4, 15 is an LED light source,
15a is a red LED, 15b is a green LED, 15c is a blue LED, 16 is a reflector, and 17 is a light guide plate.

The first embodiment is a field-sequential color driving type liquid crystal display device of OCB mode liquid crystal in which a phase compensating plate is arranged in front of bend alignment liquid crystal.
The operation will be described below with reference to FIG.

First, a conductor made of Al, Ti or the like is formed on the array substrate 3 and the scanning signal lines 9 are patterned into a predetermined shape. After forming the first insulating layer 11 on the thus formed first electrode group, an a-Si layer and an n + type a-Si layer (both are not shown in the figure) are formed on a predetermined portion of the first insulating layer 11. And the semiconductor switching element 10 is formed. Further, a conductor made of Al, Ti, or the like is formed on a predetermined portion of the first insulating layer 11 and the semiconductor switching element 10, and a second electrode group made of the video signal line 8 is patterned into a predetermined shape.

Next, the second insulating layer 12 made of SiNx or the like is formed on the array substrate 3 on which the second electrode group is formed. The second insulating layer 12 also serves as a protective film that protects the semiconductor switching element 10. Further, the pixel electrode 7 is formed of an ITO film which is a transparent conductor.

After that, alignment films 14a and 14b made of polyimide or the like are formed on the array substrate 3 and the counter substrate 4 to align the molecules of the liquid crystal layer 5. In the OCB mode liquid crystal display element as in the invention of the present application, the array substrate 3 and the counter substrate 4 are rubbed, but the directions are parallel to each other and are in parallel alignment. The counter substrate 4 is provided to face the array substrate 3, and the counter electrode 6 and the black matrix layer 13 are formed in a predetermined pattern. The array substrate 3 and the counter substrate 4 thus manufactured each have an initial orientation in a predetermined direction, and after adhering the peripheral portions with a sealant, the liquid crystal layer 5 is injected and sealed.

The semiconductor switching element 10 is on / off controlled by a drive signal input from the video signal line 8 and the scanning signal line 9. Then, an electric field is generated by a voltage applied between the pixel electrode 7 connected to the semiconductor switching element 10 and the counter electrode 6, the orientation of the liquid crystal layer 5 is changed, and the brightness of each pixel is controlled. Is displayed.
In the liquid crystal display device of the present application, liquid crystal molecules are in a splay alignment state in which the liquid crystal molecules are aligned substantially parallel to each other when no voltage is applied initially, and the alignment of the liquid crystal is transferred to the bend alignment state used for display. In order to carry out this transition, a relatively large transition voltage, for example, about 25 V was applied to the liquid crystal layer.

As described above, the OCB mode liquid crystal display element has a substrate and a liquid crystal, and displays by applying a voltage to the liquid crystal, and a zero voltage alignment state when no voltage is applied to the liquid crystal and a display state. It is a kind of liquid crystal display element that is different from the display orientation state used and is transferred by applying a transition voltage from the zero voltage orientation state to the display orientation state, and can realize a display with a high-speed response and a wide viewing angle.

In the first embodiment, the liquid crystal layer 5 has a narrow gap of 2 μm so that the total rise and fall response time is reduced to 1.5 msec or less. The liquid crystal material has a refractive index anisotropy Δn of 0.2.
A high modulation rate of 90% or more could be realized by using a large value of 8.

Further, since the first embodiment is a liquid crystal display device of the field sequential color display system,
A color filter, which is indispensable for a normal active matrix type color liquid crystal display device, is not required. Instead, the backlight 2 has red (R), green (G), and blue (B).
LED light sources 15a, 15b, 1 capable of emitting each color of
5c is required. The light emitted from the LED light source 15 is
The light is reflected by the reflection plate 16 and is repeatedly reflected by the light guide plate 17 to enter the liquid crystal panel 1. In this way, the liquid crystal panel 1
RGB light source 15a, 15b, 1
5c is switched in time sequence and the light transmission state of the liquid crystal panel 1 is controlled in synchronism therewith, whereby color display is performed with additive color mixture in terms of time.

With the above structure, the transmittance of the panel is remarkably improved as compared with the conventional method using the color filter, so that not only a bright liquid crystal panel can be obtained, but also the light source 15 has a high color purity LED. By using
It is possible to realize a color reproducibility of 100% or more in NTSC ratio, which is much higher than that of the conventional method. That is, it is possible to obtain a high-quality image with high-speed response, wide viewing angle, high brightness, and high color reproducibility, which is particularly suitable for moving images.

Next, the operation and effect of the panel structure according to the first embodiment will be described. 3A and 3B are plan views showing the configuration of the display unit of the liquid crystal panel according to the first embodiment of the present invention, and FIG. 3A shows the rough display unit and the high-definition display unit separately. In that case, FIG. 3B shows a case where the rough display portion and the high-definition display portion are integrally displayed.

FIGS. 1A and 1B are plan views showing pixel states in the vicinity of the boundary between the rough display portion and the high definition display portion of the liquid crystal panel according to the first embodiment of the present invention.
FIG. 1A shows a pixel state when the rough display portion and the high-definition display portion are individually displayed, and FIG. 1B shows a pixel state when the rough display portion and the high-definition display portion are integrally displayed.

In FIG. 3, 1a is a rough display portion, 1b is a high definition display portion, and 1c is a boundary portion between the rough display portion 1a and the high definition display portion 1b.

In FIG. 1, 7a is a red pixel of the rough display portion 1a, 7b is a green pixel of the rough display portion 1a, 7c is a blue pixel of the rough display portion 1a, 7d is a red pixel of the high definition display portion 1b,
Reference numeral 7e is a green pixel of the high definition display portion 1b, and 7f is a blue pixel of the high definition display portion 1b.

In the first embodiment, the rough display section 1
The size of one pixel of a, for example, the red pixel 7a is set to a size corresponding to nine red pixels 7d of the high-definition display portion 1b. Here, the nine pixels are used for the rough display unit 1a and the high-definition display unit 1b. When the same video signal source is sent, the horizontal direction is RGB so that a screen with the same aspect ratio can be displayed.
3 times the vertical direction, and 3 times in the vertical direction, for a total of 9 times, and for the same reason, 81 times, 729 times,
.., and 9 are preferably n powers.

With such a structure, it is possible to display the image information on the rough display portion 1a and the character information on the high definition display portion 1b as shown in FIG. 3A. In the first embodiment, the high-definition display unit 1b can display 9 times the amount of information as compared with the related art.

On the other hand, when it is desired to display the video information on a screen as large as possible, it is possible to integrally display the same video information as the coarse display section 1a on the high definition display section 1b as shown in FIG. 3 (b). In this case, the same video signal that is input to one pixel 7a of the rough display unit 1a is input to nine pixels of the high-definition display unit 1b, that is, 7d1, 7d2, 7d3, 7d4, 7d.
It suffices to drive so as to input to 5, 7d6, 7d7, 7d8 and 7d9.

With such a configuration, it is possible to display large video information in the case of integral display, and video information and a large amount of high-definition character information in the case of individual display.

In the first embodiment, when the integrated display is performed, it is premised that the same image information as the coarse display section 1a is integrally displayed on the high-definition display section 1b. Therefore, the size of one pixel of the coarse display section is large. The size is set to be equivalent to nine pixels of the high-definition display section, but it is not necessary to be nine when not integrally displayed, and two or more pixels are high-definition display. It goes without saying that it is effective for.

(Second Embodiment) A second embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a block diagram showing the structure of a liquid crystal display device according to the second embodiment of the present invention. The second embodiment is an embodiment in which a switching unit is provided which can freely switch between a mode in which the coarse display unit and the high-definition display unit are integrally displayed and a mode in which they are separately displayed separately. It differs from the first embodiment in the point.

In FIG. 4, 18 is a changeover switch, and 19
Is a drive signal processing unit, and 20 is a panel drive unit.

When it is desired to display video information on a screen as large as possible, when the same video information as the rough display portion 1a is integrally displayed on the high definition display portion 1b, the rough display portion 1a and the high definition display portion 1 are displayed.
Since the aperture ratio is different from that in b, the brightness is recognized as uneven brightness because the brightness is different in the distribution of the same brightness of the backlight.

Therefore, in a structure in which the brightness of the backlight is evenly distributed, the driving voltage for white display is set small in the coarse display portion 1a having a large aperture ratio, and white display is performed in the high-definition display portion 1b having a small aperture ratio. The drive voltage of is increased (in the case of normally white). The darker image, that is, the high-definition display portion 1b is matched with the luminance to eliminate the luminance unevenness.

However, when the image information is displayed on the rough display portion 1a and the character information is displayed on the high-definition display portion 1b without the integrated display, it is difficult to recognize uneven brightness even if the brightness is different. It is not necessary to reduce the brightness to such a structure.

In the second embodiment, by providing the changeover switch 18, it is possible to freely switch between a mode in which the rough display portion 1a and the high-definition display portion 1b are integrally displayed and a mode in which they are separately displayed separately. Then, the drive signal processing section 19 selects a drive method capable of displaying an optimum image for each and sends it to the panel drive section 20.

With such a structure, an image having no brightness unevenness, though the brightness is slightly lowered when integrally displayed,
Further, when individually displayed, it is possible to simultaneously display a bright image and a large amount of high-definition character information.

Even if the backlight 2 is distributed in such a manner that the rough display portion 1a having a large aperture ratio is dark and the high definition display portion 1b having a small aperture ratio is bright, the same effect can be obtained. Such a configuration may be determined by the density distribution of the scattering dots provided on the back surface of the light guide plate 17. Alternatively, in a direct type backlight, it is possible to obtain a desired luminance distribution by devising the arrangement of the light source.

[0049]

As described above, the liquid crystal display device according to the present invention can achieve the following operational effects. That is, it is possible not only to obtain a high-quality image with high-speed response, wide viewing angle, high brightness, and high color reproducibility, which is particularly suitable for moving images, without extremely increasing power consumption. Since it is possible to obtain a liquid crystal display device capable of displaying a large amount of character information and bright and high-quality video information simultaneously or individually, the industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a plan view showing a pixel state in the vicinity of a boundary between a rough display section and a high definition display section of a liquid crystal panel according to a first embodiment of the present invention (a) The rough display section and the high definition display section are individually displayed. Figure (b) Figure when the coarse display and high-definition display are integrated

FIG. 2 is a configuration diagram of the liquid crystal display device according to the first embodiment of the present invention (a) a sectional enlarged view (b) an enlarged plan view of a pixel portion.

FIG. 3 is a plan view showing a configuration of a display unit of the liquid crystal panel according to the first embodiment of the present invention (a) a view in which a rough display unit and a high-definition display unit are individually displayed (b) a rough display unit and a high display Diagram of integrated display of fine display

FIG. 4 is a block diagram showing a configuration of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a conceptual diagram of a liquid crystal panel used in a conventional field sequential color liquid crystal display.

[Explanation of symbols]

1 LCD panel 1a Rough display section 1b High-definition display 1c boundary 2 backlight 3 array substrate 4 Counter substrate 5 Liquid crystal layer 6 Counter electrode 7 pixel electrode 7a Red pixel of rough display section 1a 7b Green pixel of rough display section 1a 7c Blue pixel of rough display section 1a 7d Red pixel of high definition display section 1b 7e Green pixel of high-definition display section 1b 7f Blue pixel of high definition display section 1b 8 video signal lines 9 scanning signal lines 10 Semiconductor switching element 11 First insulating layer 12 Second insulating layer 13 Black matrix layer 14 Alignment film 15 LED light source 15a Red LED 15b green LED 15c blue LED 16 Reflector 17 Light guide plate 18 Changeover switch 19 Drive signal processing unit 20 panel drive 50 display panel 51 Bend Alignment Liquid Crystal Cell 52 glass substrate 53 Phase compensation plate 54 LCD 55 Crossed polarizer 57 surface light source

Claims (11)

[Claims] 1. A liquid crystal panel, a light source for irradiating the liquid crystal panel, and driving means for time-sequentially switching the color of the light source and controlling the transmission or reflection state of the liquid crystal panel in synchronization therewith, In a liquid crystal display device that performs color display with various additive colors, the liquid crystal panel includes a display portion including a plurality of display regions including a rough display portion and a high definition display portion. . 2. The liquid crystal display device according to claim 1, wherein the size of one pixel of the rough display portion corresponds to the size of a plurality of pixels of the high definition display portion. 3. A mode in which a plurality of displays including the rough display section and the high-definition display section are displayed, and a mode in which the rough display section and the high-definition display section are integrated to display one image. The liquid crystal display device according to claim 1, further comprising: 4. The size of one pixel of the rough display section is substantially equivalent to the size of the n-th power of 9 pixels of the high-definition display section (n is an integer of 1 or more). The liquid crystal display device according to claim 2. 5. A mode in which a plurality of displays including the rough display section and the high-definition display section are displayed, and a mode in which the rough display section and the high-definition display section integrally display one image. 4. The liquid crystal display device according to claim 3, further comprising switching means for freely switching between the two. 6. In a mode in which at least the rough display section and the high-definition display section integrally display one image, the brightness of the rough display section and the brightness of the high-definition display section are substantially the same brightness. The liquid crystal display device according to claim 4, wherein the liquid crystal display device is configured as follows. 7. The liquid crystal display device according to claim 6, wherein the brightness of the rough display section is configured to be substantially the same as the brightness of the high definition display section. 8. The liquid crystal display device according to claim 7, wherein the drive unit is configured such that the brightness of the rough display section and the brightness of the high definition display section are substantially the same. 9. The liquid crystal display device according to claim 7, wherein the brightness distribution of the light source is configured such that the brightness of the rough display section and the brightness of the high definition display section have substantially the same brightness. 10. The liquid crystal display device according to claim 1, wherein the light source is an LED element. 11. The liquid crystal display device according to claim 1, wherein the liquid crystal panel is an OCB mode in which a phase compensating plate is provided in front of a bend alignment liquid crystal.