JPH1074069A - Color liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the necessity of a color switching circuit even though a delta array is selected. SOLUTION: The delta array, in which same color pixels are shifted for equivalent to one and half pixels in top and bottom lines, is selected for liquid crystal display(LCD) panel 11. Signal lines 21 supply primary color signals from an X direction driver 12. The lines 21 connect the signal electrodes of the same color signals which are shifted for equivalent to one and half pixels in the top and bottom lines. Thus, one signal line is supplied with only one primary color signal and color switching circuits are not required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display using a combination of three primary color filters and a liquid crystal shutter.

[0002]

2. Description of the Related Art In recent years, liquid crystal display panels have attracted attention because of their advantages such as low power consumption, and have been widely used as monitors and display devices for computer-related equipment. Conventionally, liquid crystal is used as a simple light on / off shutter,
Many screens were relatively simple with black and white display.

There are various types of color display using a liquid crystal panel, but a method using three primary color filters is most promoted. The reason is that the nature of the twisted nematic mode of the liquid crystal has been investigated and the color reproduction range is wide.

FIG. 3 shows an example of a conventional color liquid crystal panel using a combination of a twisted nematic liquid crystal and a color filter. In this figure, R11, R12,.
, Etc. represent red (R) pixels, G11, G12,.
, Etc. indicate green (G) pixels, and B11, B12,... B21, etc. indicate blue (B) pixels. The three RGB pixels forming the set of three primary colors are alternately shifted by half a pixel in the horizontal direction (hereinafter referred to as the X direction) between odd lines and even lines so that each of the three RGB pixels forms a vertex of a triangle.
The pixels of the same color are shifted by one and a half pixels. Thereby, the arrangement of RGB becomes a delta shape, and lines in the vertical and oblique directions are made inconspicuous.

A line 1 indicated by a dotted line indicates a signal line, and a line 2 indicated by a solid line indicates a scanning line (L1, L2,
L3 ...). A signal from which a combination of two colors is alternately switched in a horizontal cycle is led from a signal line 1 by a color switching circuit described later. Further, a scanning signal is supplied to the scanning line 2.

On the other hand, a liquid crystal shutter shown in detail in FIG. In this liquid crystal shutter, a liquid crystal is filled between a pair of transparent electrodes, and the shutter operation of the liquid crystal is performed by a thin film transistor T in this example.
It is controlled by FT3. The above thin film transistor TFT3
Are formed at the lower right corner of each square pixel. The reason why the thin film transistor TFT is moved to the corner of the pixel is to connect the thin film transistor TFT to the scanning line 2 and the signal line 1 as close as possible.

One liquid crystal cell 10 is arranged between the scanning line 2 and the signal line 1 and has the above-mentioned thin film transistor TF.
T and a liquid crystal layer LD sandwiched between transparent electrodes T1 and T2, and a scanning electrode P connected to a gate G of the TFT.
1 is supplied with a scanning signal via a scanning line 2 and a TFT
Signal line 1 to the signal electrode P2 connected to the drain D of
The primary color signal is supplied via the. The source S of the TFT is connected to one transparent electrode T1, and the other transparent electrode T2 is connected to a common potential point (earth). Thus, one pixel is formed.

FIG. 5 is a block diagram showing an example of a circuit for driving the liquid crystal panel having the above configuration. Reference numeral 11 denotes a liquid crystal panel having the configuration shown in FIG. 3, which is driven by an X-direction driver 12 and a Y-direction driver 13. The output line of the X-direction driver 12 is the signal line 1 in FIG.
And the output line of the Y-direction driver 13 corresponds to the scanning line 2.

Terminals 14, 15, and 16 are for three primary color signals RGB.
Are input terminals. These terminals 14, 15, 1
6 is input to the polarity switching circuit 17, and becomes a signal R'G'B 'whose polarity is alternately inverted at the timing of the vertical synchronizing signal Vsy from the terminal 21. The reason that the polarity of the primary color signal is switched every one vertical scanning period is that durability is reduced when a voltage of the same polarity is continuously applied to the liquid crystal.

Next, the signal R 'from the polarity switching circuit 17 is output.
G'B 'is input to a color switching circuit 18, where the primary color signal is switched for each line. This switching is performed because the arrangement of the three primary color pixels is shifted between odd lines and even lines. If the output RB, GR, BG is a repetitive signal of, for example, R'G'B'R '... During even line scanning, switching is performed so as to be a repetition signal of B'R'G'B '. Accordingly, the signal supplied via the X-direction driver 12 is, for example, the signal RB1
The signal line 1 leading to (see FIG. 3) is switched to become a signal of R 'when the scanning line L1 which is the first scanning line is being scanned, and become a signal of B' when L2 is being scanned. . The storage timing of the line memory 19 is controlled by the horizontal synchronizing signal Hsy from the terminal 20, and stores the three primary color signals for one horizontal scanning period. Then, at the timing of the next horizontal synchronization signal, the X-direction driver 1
2 is supplied to the liquid crystal display panel.

In such a panel type display device, when a bias is applied to the gate of the thin film transistor TFT shown in FIG. 4, conduction between the drain and the source is conducted, and the signal from the signal line 1 at that time is applied to the transparent electrode T1. And T1, T2
A potential difference is generated between the transparent electrodes T1 and T2.
A light shutter operation is performed according to the inter-voltage. For example, when displaying white, the signals RB, GR, BG from each signal line 1 are at a predetermined level, and the signals R1, R2,.
1, G11, B11 → B21, R21, G21 → R3
1, G31, B31 → B41, R41, G41, etc., the liquid crystal layer LD is in a transmission state.

By the way, in the liquid crystal panel as shown in FIG. 3, the number of scanning lines 2 is set to, for example, about 480,
If interlaced scanning is performed as in a television receiver using a cathode ray tube, there is a problem that when displaying a moving image, double blurring or flicker of 15 [Hz] occurs.

In general, in interlaced scanning, an image in which the signal of the first field and the signal of the second field are displayed at the same time is displayed. Therefore, the image 1/60 second before and the current image are always displayed simultaneously. Will be. However, the liquid crystal cell needs one frame period, that is, 3
Since there is a property of storing the state of being written about 1/0 second, if there is a motion in the image, a shift occurs between the image of the first field and the image of the second field, and double blur occurs. This is the cause. Further, the frame memory effect is an indispensable property for a high contrast display in a liquid crystal display device.

The reason why the flicker of 15 [Hz] occurs is as follows.
In the case of interlaced scanning, the operation of the polarity switching circuit 17 is performed once per frame (a signal of the same polarity is always applied to odd-numbered scanning lines and even-numbered scanning lines for each field). A cycle in which the polarity of the voltage held by the cell is switched is a two-frame cycle. On the other hand, the TFT has slightly different characteristics depending on the polarity of the applied voltage, and changes the luminance every two frames.
This originally occurs at 30 [Hz] in the case of sequential scanning, but at 15 [Hz], it is felt as a stimulus to human eyes.

Incidentally, the double blur phenomenon caused by the frame memory effect is a problem in television receivers which perform special display using a frame memory. As a countermeasure, circuits such as motion detection, motion correction, and line interpolation are used. Are provided to prevent images from being duplicated, but these circuits have a large-scale configuration, and it is economically difficult to apply them to a display device such as a liquid crystal television receiver.

Therefore, as a measure applicable to a liquid crystal television receiver, it is conceivable to provide two line memories 19 for two lines and to supply the same signal to two adjacent scanning lines. The necessity increases the cost.

A display method in which a black signal is displayed every other horizontal scanning line and one screen is always constituted by a signal for one field is conceivable, but this may cause a liquid crystal screen originally having a low light transmittance to be further darkened. Not preferred.

Further, in order to improve the screen quality, since the same color pixels adopt a delta arrangement shifted by one and a half pixels, it is necessary to supply two colors to one signal line.
For this reason, there is a problem that a color switching circuit is required.

[0019]

As described above, the conventional color liquid crystal display device described above employs a delta arrangement in which pixels of the same color are shifted by one and a half pixels in the upper and lower lines.
There is a problem that two colors must be supplied to the signal line, and a color switching circuit is required.

According to the present invention, the same color pixel has 1
It is an object of the present invention to provide a color liquid crystal display device that can eliminate the need for a color switching circuit even when a delta arrangement in which pixels are shifted by half a pixel.

[0021]

In the color liquid crystal display device according to the present invention, R (red), G (green), and B (blue) pixels are arranged in a delta arrangement, and the upper and lower lines have the same color. A liquid crystal panel in which pixels are shifted by 1.5 pixels in the horizontal direction; scanning signal supply means for supplying a scanning signal to the scanning electrodes provided in the pixels in each line; Signal supply means having three types of signal supply lines for supplying primary color signals to signal electrodes of pixels of the same color shifted by 5 pixels.

In the present invention, the liquid crystal panel adopts a delta arrangement in which pixels of the same color are shifted by 1.5 pixels in the upper and lower lines. The signal supply means has three types of signal supply lines, and each signal supply line is arranged in an R pixel, G
Connect to pixel or B pixel. That is, the signal supply means supplies one primary color signal to the pixel by one signal supply line. This eliminates the need for a color switching circuit.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a liquid crystal panel diagram showing one embodiment of a color liquid crystal display device according to the present invention. FIG. 2 is a block diagram showing an example of a circuit for driving the embodiment of FIG.

In FIG. 1, reference numeral 11 denotes a liquid crystal panel.
21 is a signal line, 22 is a scanning line, and 12 is X
A direction driver 13 is a Y-direction driver. The Y-direction driver 13 supplies a scanning signal to the scanning line 22. In the present embodiment, the liquid crystal panel 11 employs a delta arrangement in which pixels of the same color are shifted by one and a half pixels in upper and lower lines.

Each scanning line 22 has a corresponding X
Is connected to the TFT 3 ′ of the directional pixel.
T3 'is configured at the lower right corner for each pixel on the odd line,
Each pixel of the even-numbered line is configured at the lower left corner. TF
The configuration of T3 'is similar to that of FIG.

On the other hand, in this embodiment, since color switching is not performed for each line, the signal line 21 is B '
The signals are derived in the order of R′G ′ → B′R′G ′ →. Then, as shown by a broken line in FIG.
One set of the same color pixels each shifted by one and a half pixels on the upper and lower lines is selectively connected, and all the same color pixels shifted by one horizontal pixel and a half in the vertical direction are connected by one line. In this case, the TFT 3 'of each pixel of the even-numbered line is formed in the lower left corner, so that the signal line 21 extending between the lines can connect the same color pixel by bending by half a pixel.

However, pixels on even lines are selected at the left end of the screen, and pixels on odd lines are selectively connected at the right end of the screen.

The circuit shown in FIG. 2 is different from the circuit shown in FIG.
8 is deleted. That is, the R ', G', and B 'signals from the polarity switching circuit 17 are supplied directly to the line memory 19.

In the embodiment thus constructed, the R ', G', B 'signals from the polarity switching circuit 17 are directly applied to the line memory 19. The line memory 19 is
The R 'signal is supplied to the signal line 21 connected to the R pixel, the G' signal is supplied to the signal line 21 connected to the G pixel, and the B 'signal is supplied to the signal line 21 connected to the B pixel. . Each signal line 21 is bent to the left and right by half a pixel and connected to the TFT 3 ′ of the same color pixel, and primary color signals from the same signal line 21 to upper and lower lines of the same color pixel shifted to the left and right by 1.5 pixels. Supplied.

For example, a signal line for supplying a signal to the pixel R11 on the first line is composed of the pixel R21 on the second line and the third line.
The R 'signal is also supplied to the pixel R31 on the line, the pixel R41 on the fourth line, and so on. The same applies to other color pixels, and primary color signals are supplied to the same color pixels connected by broken lines in FIG. 1 through the same signal line.

The TFT 3 'of each pixel is turned on when a scanning signal is supplied, and is driven in accordance with the R', G ', and B' signals. Thus, the liquid crystal panel 11 displays an image for each field on one screen.

Even in the case where the pixel array adopts the delta arrangement in which the same color pixels are shifted by one and a half pixels as described above, the color switching circuit becomes unnecessary because each signal line 21 is connected to the same color pixel. That is, the liquid crystal panel of FIG.
The color display in the delta arrangement can be performed without providing the color switching circuit 18 in the above.

[0033]

As described above, according to the present invention, a liquid crystal image can be displayed with high image quality, and a color switching circuit can be dispensed with even in a delta arrangement.

[Brief description of the drawings]

FIG. 1 is a schematic view of a liquid crystal panel showing one embodiment of a color liquid crystal display device according to the present invention.

FIG. 2 is a circuit diagram showing an example of a circuit for driving the liquid crystal panel of FIG.

FIG. 3 is a schematic view showing an example of a conventional liquid crystal panel.

FIG. 4 is an explanatory diagram showing a structure of a liquid crystal cell.

FIG. 5 is a block diagram showing a configuration of a circuit for driving the liquid crystal panel of FIG. 3;

[Explanation of symbols]

11: liquid crystal panel, 12: X direction driver, 13: Y direction driver, 17: polarity switching circuit, 21: signal line,
22 ... scan line

Claims (2)

[Claims] 1. R (red), G (green), and B (blue) pixels are arranged in a delta arrangement, and pixels of the same color are arranged horizontally shifted by 1.5 pixels in upper and lower lines. A liquid crystal panel, a scanning signal supply unit for supplying a scanning signal to a scanning electrode provided in the pixel of each line, and a primary color on a signal electrode of a pixel of the same color shifted by 1.5 pixels horizontally in upper and lower lines. A color liquid crystal display device comprising: signal supply means having three types of signal supply lines for supplying signals. 2. The method according to claim 1, wherein the scanning electrode and the signal electrode are arranged on the right side of each pixel in a predetermined line, and are arranged on the left side of each pixel in lines above and below the predetermined line. A color liquid crystal display device as described in the above.