JPH04165331A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To perform enough neat display of white by a method wherein one set of first display picture elements comprising one set of picture element electrodes of a first picture element electrode group and one set of second display picture elements comprising one set of picture element electrodes of a second picture element electrode group are arranged in the same color. CONSTITUTION:Four picture elements R, G, G, and B, arranged in two-line x two-row in a shape of a square partitioned by a cross, of display picture elements comprising a switching element 16, a picture element electrode 17, connected to the switching element 16, and a color filter 21 positioned facing the picture element electrode 17 form one display picture element 3. The picture elements 3 are laterally and longitudinally arranged in a state that a relative position relation between R, G, G, and B in each picture element 3 is kept in a constant state. In arrangement of 2-line X 2-row, first line is R and G from a left to a right and a second line is G and B from a left to a right. This constitution performs enough neat display of white.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an active matrix color liquid crystal display device.

(Prior Art) Among flat panel displays that are being developed to replace CRTs, the development of active matrix liquid crystal displays is particularly remarkable. Color expression in this type of liquid crystal display device is achieved by forming color filters of three primary colors, for example, red (R), green (G), and blue (B), corresponding to each display pixel, and by additive color mixing.
The purpose is to express the desired color.

Here, display pixels display each color of R, G, and B.
A unit consisting of a plurality of display pixels and capable of expressing one meaningful color by additive color mixing is called a display picture element.

The above-described arrangement of color filters is optimized depending on the purpose of use. For example, color filters for full-color TVs have a delta-type arrangement as shown in Figure 7, while color filters for office automation equipment such as computer terminals have vertical stripes as shown in Figure 8. It is an array of types. In the one shown in Figure 7,
Three pixels of R, G, and B arranged in a delta shape constitute one picture element 1.
In the one shown in FIG. 8, three R, G, and B pixels arranged in the horizontal direction in the figure form one picture element 2. The reason why TV and OA applications are different is that the flow of data to be displayed is different, and the color filters are also optimized to suit each purpose.

Incidentally, recently, it has become common to use teletext in TV broadcasts and to display full-color images on the displays of computer terminals. That is, there is a growing demand for displaying different types of data on one display device. However, when a color filter optimized for certain display data is used, a problem arises in that display quality deteriorates for different display data.

For example, when a color filter with a delta-type arrangement optimized for TV use is used, a problem arises in that lines are displayed unevenly and it is difficult to display fine characters.

Additionally, LCD devices that use color filters in a vertical stripe arrangement that are optimized for OA have the problem of slightly lower display resolution than those that use color filters in a delta arrangement. be. In addition, each pixel is elongated and pixels of the same color are lined up in a vertical line, so there is the problem that monochrome display looks bad. Furthermore, display signal lines are provided on the substrate along each row of pixels arranged vertically in FIG. 8, and scanning signal lines are provided along each row of pixels arranged horizontally. Since the element is divided horizontally into three, the number of display signal lines is three times the number of columns of picture elements, and the drive IC
The number of connections is much greater on the display signal line side than on the scanning signal line side. Therefore, there has been a problem in that manufacturing problems such as a decrease in yield during mass production are likely to occur.

Furthermore, as shown in FIG. 5, there is also a color filter in which one picture element 3 is composed of 84 R, G, and G pixels arranged in a 2 row and 2 column shape. A liquid crystal display device using this color filter has 4/3 times the total number of signal line connections when the number of picture elements is the same, compared to a device using a vertical stripe type color filter shown in Figure 8. However, since the signal line connection points are evenly distributed on each side of the board, it has the advantage that mounting problems are less likely to occur compared to the vertical stripe type. In addition, since the pixels are arranged in a straight line in all directions, it is very suitable for graphics purposes.

By the way, in a conventional liquid crystal display device based on the pixel arrangement of 2 rows and 2 columns, one scanning signal line is connected to the pixel electrodes of the pixels arranged in a row on one side of the scanning signal line, and a switching device consisting of a thin film transistor is used. A structure was adopted in which connections were made through elements.

That is, one scanning signal line corresponds to the pixel electrodes in the rows R, G, R, G, . . . or G, B, . . . in FIG.
They are connected to the pixel electrodes of rows G, B, . . . , respectively. Therefore, only R, G or G, B are displayed using one scanning signal line, and the display using one scanning signal line is white (
It was impossible to do so. As a result, white in particular could not be displayed sufficiently clearly. However, although this may be fine for OA displays that display many areas outside of white, it is a drawback that white displays cannot be displayed clearly on TVs that display many white areas.

(Problems to be Solved by the Invention) As mentioned above, liquid crystal display devices using color filters arranged in a delta type have a problem in that it is difficult to display fine characters. Liquid crystal display devices using color filters have had problems with manufacturability.

On the other hand, liquid crystal display devices based on an old-fashioned pixel arrangement of 2 rows and 2 columns have the advantage of not only being able to display excellent graphics but also being easy to manufacture. Since the structure was such that one scanning signal line was connected to the pixel electrodes of display pixels arranged in a row on one side of this scanning signal line, it was not possible to make the display by one scanning signal line white, and as a result, In particular, there was a problem that white could not be displayed clearly enough.

The present invention is an attempt to solve these problems, and aims to enable a color liquid crystal display device based on an old-fashioned pixel arrangement to display white in a sufficiently clear manner. It is.

[Structure of the invention]

(Means for Solving the Problems) In the color liquid crystal display device of the present invention, a plurality of display signal lines and a plurality of scanning signal lines are arranged in a matrix, and a pixel is connected to each intersection via a switching element. a first substrate to which electrodes are connected; a second substrate provided with a common electrode and a color filter disposed opposite to the pixel electrode; and held by the first substrate and the second substrate. Equipped with a plurality of display pixels composed of a liquid crystal display and
These display pixels are arranged in a traditional character shape to constitute one display picture element. a first pixel electrode group connected to the first scanning signal line via the switching element;
and a second pixel electrode group connected to a second scanning signal line adjacent to the first scanning signal line via the switching element, each set of two pixel electrodes being arranged in a comb shape. In addition, a set of first display pixels constituted by a set of pixel electrodes of the first pixel electrode group and a set of the second display pixels.
A set of second display pixels constituted by a set of pixel electrodes of the pixel electrode group are arranged in the same color.

(Function) In the color liquid crystal display device of the present invention, a display signal is supplied to the display signal line, and a scanning signal pulse is supplied to the scanning signal line. An appropriate voltage is applied between the pixel electrode and the common electrode, which are connected to the intersection with the scanning signal line via a switching element, and the transmittance of the liquid crystal between them changes appropriately, causing each pixel electrode to Color display is performed by additive color mixing by opposing color filters. Incidentally, the display pixels are arranged in an old-fashioned shape to constitute one display picture element, but the first display picture element is arranged through a switching element.
a first pixel electrode group connected to a scanning signal line of 2, and a second pixel electrode group connected to a second scanning signal line adjacent to the first scanning signal line via a switching element. Since the pixel electrodes are arranged in a comb shape as a set,
As a result, one scanning signal pulse causes one half of a plurality of display picture elements to be displayed at the same rate as the other half thereof.

Moreover, one set of first display pixels is formed by one set of pixel electrodes of the first pixel electrode group, and one set of second display pixels is formed of one set of pixel electrodes of the second pixel electrode group. Since the display pixels are arranged in the same color, the one half and the other half of the display pixels displayed by one scanning signal pulse contain different colors. The display using the scanning signal pulse can be made white, making it possible to visually express it as white.

(Example) Hereinafter, embodiments of the color liquid crystal display device of the present invention will be described in detail with reference to FIGS. 1 to 5.

FIG. 2 is a longitudinal sectional view of the liquid crystal panel of the active matrix color liquid crystal display device of this embodiment, and FIG. 1 is a front view showing a part of the array of switching elements and pixel electrodes.

As shown in FIG. 2, the liquid crystal panel 10 includes a first substrate 1
1 and a second substrate 12 disposed parallel to and opposite to the first substrate 11, a nematic liquid crystal 13 is held therebetween.

On the surface of the first substrate 11 facing the second substrate 12,
As shown in FIG. 1, a plurality of straight display signal lines 14 extending in the vertical direction in the drawing are formed, and
A plurality of scanning signal lines 15 are formed extending in the left-right direction in the drawing. The display signal line 14 and the scanning signal line 15 cross each other perpendicularly, but the scanning signal line 15 extends below the display signal line 14 and is electrically insulated from each other.

Furthermore, switching elements 16 are formed at the intersections of each display signal line 14 and each scanning signal line 15, and display pixel electrodes 17 are formed at positions between each display signal line 14 and each scanning signal line 15, respectively. It is formed.

The switching element 16 is a thin film transistor, and has a semiconductor interposed between a gate electrode 18 extending integrally from the scanning signal line 15, a source electrode consisting of the display signal line 14, and the source electrode. It has a drain electrode 19 with an insulator interposed between it and the electrode 18, and this drain electrode 19 is connected to the pixel electrode 17 located between the same display signal line 14 and scanning signal line 15. In FIG. 2, the signal lines 14 and 15 or the switching element 16 are located between the pixel electrodes 17.

On the other hand, as shown in FIG. 2, each pixel electrode 17 is provided on the surface of the second substrate 12 facing the first substrate 11.
Color filters 21 are arranged vertically and horizontally to face each other. This color filter 21 is R
, G, and B are arranged as shown in FIG. That is, among the display pixels consisting of the switching element 16, the pixel electrode 17 connected to the switching element 16, and the color filter 21 facing the pixel electrode 17, R ,G,G
, B are 1 display picture element 3, and these picture elements 3 are arranged vertically and horizontally while keeping the relative positional relationship of R, G, G, and H within each picture element 3 the same. ing. In a 2-by-2 array, the first row has R and G from left to right, and the second row has G and B from left to right.

For convenience, colors R, G, and B are shown in the pixel electrode 17 in FIG. 1, which correspond to the arrangement of the color filter 21 shown in FIG. 5. In the following description, among the rows of picture elements 3 arranged in the vertical direction, the odd-numbered rows counting from the left of the screen are referred to as 81, and the even-numbered rows are referred to as b.

Furthermore, a common electrode 22 is formed over the entire surface of the second substrate 12 on the side closer to the first substrate 11 than the color filter 21 .

The gate electrode 18 of the switching element 16 connected to the scanning signal line 15 is not shown in the pixel portion corresponding to the display signal line 14 of the picture element 3 in the odd-numbered column a in the left-right IJ direction of FIG. The pixel portions corresponding to the display signal lines 14 of the picture elements 3 in even-numbered columns are extended to the upper side, and to the lower side in the figure. As a result, each switching element 16 is connected to the pixel electrode 17 located above the scanning signal line 15 to which the switching element 16 is connected in the picture element 3 in the odd-numbered column a, and in the picture element 3 in the even-numbered column. The element 3 is connected to the pixel electrode 17 located below the scanning signal line 15. In other words, in one row of pixels lined up in the left-right direction, one group of pixel electrodes 17 connected to a certain scanning signal line 15 and one group of pixel electrodes 17 connected to another scanning signal line 15 are connected to each other. Two pixel electrodes 17 in half of the picture element 3
are arranged in a comb shape as one set, and the color scheme of display pixels in each set is the same for RlG, G, and B.

Note that an illumination light source is provided behind either of the substrates 11, 12.

The nematic liquid crystal 13 is connected to the pixel electrode 1.
When no voltage is applied between these electrodes 17 and 22, the molecular axis is twisted by 90 degrees, but when the voltage is applied between the pixel electrode 17 and the common electrode 22, The molecular axis changes. As a result, the transmittance of the liquid crystal panel 10 changes in each pixel. Here, a display signal line 14 is provided between the pixel electrode 17 and the common electrode 22.
A voltage is applied as appropriate depending on the display signal supplied to the scanning signal line 15 and the scanning signal pulse supplied to the scanning signal line 15 . That is, when a scanning signal pulse is supplied to a certain scanning signal line 15 and a display signal voltage is applied to the display signal line 14, this is applied to the pixel electrode 17 via the switching element 16.
is applied to By controlling voltage application in this manner, a desired display is performed. At that time, each pixel electrode 17
Since the color filters 21 of the three primary colors face each other, color display is performed by additive color mixing of the three primary colors.

FIG. 3 is a block diagram of the active matrix driving type liquid crystal display device of this embodiment.

In FIG. 3, 31 is a control circuit, and this control circuit 31
has a data input section 32 and an output buffer 35 connected to the data input section 32 via an odd buffer 33 and an even buffer 34. This output buffer 35 is connected to a display signal line drive circuit 36, and this display signal line drive circuit 36 supplies display signals to the plurality of display signal lines 14 of the liquid crystal panel 10 at the same time. These display signal lines 14 are connected via display signal lines 37, respectively. In addition, the data input section 32
is also connected to a scanning signal line drive circuit 38, which scans these lines in order to sequentially supply scanning signal pulses to the plurality of scanning signal lines 15 of the liquid crystal panel 10. They are connected to the signal lines 15 via scanning signal lines 39, respectively. That is, scanning signal pulses are sequentially supplied to the plurality of scanning signal lines 15 from above the screen.

The control circuit 31 particularly controls the voltage of the display signal to the liquid crystal panel 10 in order to obtain a desired display.Here, the flow of the display signal will be explained.

The signal input to the control circuit 31 is input to the data input section 32.
It is separated into a scanning signal and a display signal, and the display signal is further separated into one corresponding to the picture element 3 in the odd-numbered column a and one corresponding to the picture element 3 in the even-numbered column A. and,
The display signal corresponding to the picture element 3 in the odd-numbered column a is stored in the odd-numbered buffer 33, and the display signal corresponding to the picture element 3 in the even-numbered column a is stored in the even-numbered buffer 34. Here, the timing of data input to the odd numbered buffer 33 is 1.0 compared to the even numbered buffer 34. Half time of scanning line time t 1/
It was designed to be delayed by 2t.

FIG. 4 shows an odd buffer 33 and an even buffer 34.
3 shows the timing of data transfer from the output buffer 35 to the output buffer 35. In FIG. 4, the horizontal axis is time, and from top to bottom, data transferred from the odd numbered buffer 33, data transferred from the even numbered buffer 34, and the scanning signal pulse y are shown. Further, the data transferred from the buffers 33 and 34 are shown separately for each scanning line Y. As shown in FIG. 1, one scanning line Y,
This corresponds to the pixel electrodes 17 in the 21-1st and 21st rows from the top of the screen at 0. That is, since the picture element 3 is composed of pixels arranged in 2 rows and 2 columns, the scanning signal line drive circuit 38 outputs approximately 1/1 of the signal for one scanning line time t.
Two scanning signal pulses y of time 2 are output.

Then, for the first scanning line Y, in response to the first scanning signal pulse 'I 21-1, the odd buffer 33
Data corresponding to R pixels and G pixels (hereinafter,
It's called RG data. The same applies to the GB data) and the GB data in the even number buffer 34 are mixed together and transferred to the output buffer 35. After that, the next scanning signal pulse y21
Correspondingly, data obtained by mixing the GB data in the odd numbered buffer 33 and the RG data in the even numbered buffer 34 is transferred to the output buffer 35. At this time, even number buffer 34
The data within has been switched to data corresponding to the j+1st scanning line Y141.

The data stored in the output buffer 35 is transferred to the display signal line drive circuit 36 and applied as a voltage to the liquid crystal panel 1o.

For example, in FIG. 1, the second scanning signal line 15 from the top corresponds to the scanning signal pulse y2+-1, and the third scanning signal line 15 from the top corresponds to the scanning signal pulse y2+. It can be seen that the display data for the scanning line Y1 shown in the top row of FIG. 4 is in accordance with the arrangement of R, G, G, and B pixels.

On the other hand, since the gate electrodes I8 are distributed for each picture element 3 on both sides of one scanning signal line 15, the upper half of the plurality of picture elements 3 in FIG. and the lower half will be displayed at the same ratio. If the upper half and lower half of the picture element 3 are combined, all three primary colors R, G, and B are included, so it is possible to make the display white on the screen with one scanning signal pulse y. This makes it possible to visually express the color as white.

Moreover, as described above, in the control circuit 31, the display signals inputted corresponding to the rows of the pixel electrodes 17 are decomposed for each picture element 3 and reconfigured for each scanning signal line 15. , the relative display position of each pixel on the screen can be kept constant. That is, the display signals are R, G, R, G, .
..., G, B, G, B.

...from R, G, G, B, R, G, G, B, ...
・By reconfiguring the display to , accurate display can be performed.

In this way, it is possible to provide a color liquid crystal display device that can display white with one scanning signal pulse without changing the display position.

And by being able to display white clearly enough,
Also suitable for TV use.

In addition, since it is a color liquid crystal display device based on a pixel arrangement of 2 rows and 2 columns, it is suitable for graphic display and can display fine text, and can also be used for OA applications such as computer terminal displays. .

In this way, despite the fixed pixel arrangement, the TV
Regardless of whether it is for commercial use or OA use, for any display signal,
A color liquid crystal display device that achieves good display quality can be provided.

Of course, since this is a color liquid crystal display device based on a pixel arrangement of 2 rows and 2 columns, manufacturing problems are less likely to occur.

Although it has not been specifically mentioned so far, one picture element 3 is
, G, G, and B, it goes without saying that the transmittance of the G pixel is different from other pixels so that white can be displayed properly. Two of the four pixels are G, as is well known, because humans can more easily see G than R or B. Therefore, increasing the area of G makes the screen more visible, especially outdoors, where it is difficult to see the screen. This is because it is easier to see.

In addition, the pixel displayed by one scanning signal pulse is the picture element 3.
In practice, it is necessary to add at least one scanning signal line or perform corresponding signal processing in order to display the top and bottom lines of the screen. .

Furthermore, FIG. 6 shows another arrangement of the three primary colors in the color filter 21. In this example, in a two-by-two array, the first row has R and G from left to right, and the second row has B and G from left to right. In the arrangement shown in FIG. 6, the pixels in the G section are arranged vertically, that is, along the display signal lines, so one of the two display signal lines for one row of display pixels 4 is A G signal is always applied. Therefore, the control circuit can be simplified.

〔Effect of the invention〕

As described above, according to the present invention, in a color liquid crystal display device in which display pixels are arranged in a Japanese character pattern to form one display picture element, white can be displayed with one scanning signal pulse, and white can be displayed. can be displayed clearly enough.

[Brief explanation of drawings]

1 to 5 show an embodiment of the color liquid crystal display device of the present invention, in which FIG. 1 is a front view showing an array of pixel electrodes, FIG. 2 is a vertical cross-sectional view of the liquid crystal panel, and FIG. The figure is an overall block diagram, Figure 4 is a timing diagram of display signals, and Figure 5 is a timing diagram of display signals.
The figure is a front view showing the arrangement of color filters. Also,
FIG. 6 is a front view showing a color filter arrangement of another embodiment, FIG. 7 is a front view showing a delta-type color filter arrangement for a conventional TV, and FIG. 8 is a front view showing a conventional vertical stripe for OA. FIG. 3 is a front view showing an arrangement of color filters of the mold. 3.4... Display picture element, 11... First substrate, 12... Second substrate, 13... Liquid crystal, 14... Display signal line, 15...
- Scanning signal line, 16... switching element, 17... pixel electrode, 21... color filter, 22... common electrode. Ashi

Claims (1)

[Claims] (1) A first substrate in which a plurality of display signal lines and a plurality of scanning signal lines are arranged in a matrix, and a pixel electrode is connected to each intersection through a switching element, and the pixel electrode a plurality of display pixels configured by a second substrate provided with a common electrode and a color filter disposed opposite to each other, and a liquid crystal held by the first substrate and the second substrate; In this color liquid crystal device in which display pixels are arranged in a square shape to form one display picture element, a first pixel electrode group connected to a first scanning signal line via the switching element; a second pixel electrode group connected to a second scanning signal line adjacent to the first scanning signal line via a switching element, each set of two pixel electrodes being arranged in a comb shape; , one set of first display pixels constituted by one set of pixel electrodes of the first pixel electrode group, and one set of second display pixels constituted of one set of pixel electrodes of the second pixel electrode group. A color liquid crystal display device characterized in that display pixels are arranged in the same color.