JP3397828B2 - Liquid crystal display - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a driving method thereof, and more specifically, to an LCD (Liquid Cry).
stal Display: TFT (Th
in Film Transistor: to improve an active matrix and its driving method.

[0002]

2. Description of the Related Art A conventional liquid crystal display device will be described below with reference to the drawings. FIG. 4 is a configuration diagram of a liquid crystal display device according to a conventional example. In a TFT-LCD of a liquid crystal display device according to a conventional example, as shown in FIG. 4, a first glass substrate (2) and a second glass substrate (9) are fixed by facing each other with a space of several μm therebetween. , Liquid crystal layer in the gap (6)
It has a structure that is formed. On the first glass substrate (2), a drain bus line (5
B) and a gate bus line (5A) which is a scanning line are arranged in a matrix, and a TFT (4) and a pixel electrode (3) made of a transparent ITO film or the like are arranged at the intersections thereof. Further, on the second glass substrate (9), a common counter electrode (7) and a common color filter (8) are arranged corresponding to all pixel electrodes.

This TFT-LCD has a first polarizing plate (1)
And a second polarizing plate (10) are sandwiched between the two polarizing plates, and white light is incident on the polarizing plate to obtain a transmissive liquid crystal display device according to a conventional example. In addition, the color filter (8) is R (red), G
Each pixel electrode (3) consists of three primary colors (green) and B (blue).
Are arranged one by one corresponding to.

[0004]

However, according to the above-mentioned conventional device, as shown in FIG. 6, for each pixel, a color filter (8) of one color corresponds to each pixel and the counter electrode ( 7) was common to all pixels. Therefore, regarding the unit for displaying the three primary colors of R (red), G (green), and B (blue) (hereinafter referred to as picture element),
Three pixels are required for one picture element.

In the liquid crystal display device according to the conventional example, when about 480 × 640 = 307200 picture elements are required for one screen, three pixels are required for one picture element, so that 480 × 640 × 3 = 921600. Pixels are required, and three times as many pixels as necessary and required TFTs are required. Therefore, an enormous number of TFTs are required, and accordingly, the number of gate bus lines and drain bus lines is increased, which goes against high definition and high aperture ratio, and the number of TFTs is increased. There was a problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art. The second transparent substrate facing the pixel electrode provided on the first transparent substrate is provided with the pixel electrode. First to third counter electrodes are provided for each of them, and the first counter electrode has a first colored film for displaying red and the second counter electrode has a second colored film for displaying green. The above problem is solved by the liquid crystal display device according to the present invention, which has pixels each provided with a third colored film for displaying blue color on the third counter electrode, and the above first problem is solved during one frame. ~
The above-mentioned problem is solved by the driving method of the liquid crystal display device of the present invention, wherein the first to third offset signals are sequentially input to the third counter electrode, and the drive control signal is input to the pixel electrode. In the method for driving a liquid crystal display device according to the present invention, further, red display processing or non-display processing is first performed within one frame, then green display processing or non-display processing is performed, and then blue display processing is performed. Alternatively, the above problem can be solved by inputting the first to third offset signals for the non-display processing to the first to third counter electrodes.

[0007]

[Operation] According to the liquid crystal display device of the present invention, the first to third counter electrodes, which face the pixel electrodes of the first transparent substrate and receive the first to third offset signals respectively, are provided. A first colored film for displaying red is provided on the first counter electrode, a second colored film for displaying green on the second counter electrode, and a third colored film for displaying blue on the third counter electrode. The colored film of
Each has a pixel provided.

Therefore, unlike the conventional example in which only one color can be displayed corresponding to one pixel electrode, that is, one pixel,
Since the counter electrode is provided for one pixel electrode so as to correspond to the three primary colors, one pixel can be divided into three regions for use. Further, according to the driving method of the liquid crystal display device of the present invention, the first to third offset signals are sequentially input to the first to third counter electrodes and the drive control signal is supplied to the pixel electrodes during one frame. You are typing.

Therefore, unlike the conventional example in which only one color can be displayed corresponding to one pixel electrode, that is, one pixel,
By sequentially inputting independent first to third offset signals to the first to third counter electrodes corresponding to the three primary colors, one pixel can display the three primary colors. By devising the method of inputting the third offset signal, it becomes possible to display a mixed color of the three primary colors.

Therefore, since one pixel can display the three primary colors of red, green and blue, the TFT associated with the pixel can be displayed.
And the number of gate bus lines and drain bus lines connected to the TFT are small (only 1/3 of the conventional), high integration and high aperture ratio are possible, and the yield is also improved. . In the method for driving a liquid crystal display device according to the present invention, a red display process or a non-display process is first performed within one frame, a green display process or a non-display process is performed next, and a blue display process or a non-display process is then performed. The first to third offset signals for display processing are input to the first to third counter electrodes.

For example, when it is desired to display purple, which is a mixed color of red and blue, the display processing for red is performed within one frame, then the non-display processing for green is performed, and then the display processing for blue is performed. In this case, even though blue is actually displayed after red is displayed, the display is switched instantly, so it is not recognized by the naked eye, and afterimages such as Due to the effect, it is recognized as if purple, which is a mixed color of red and blue, is displayed. Therefore, the same effect as that when a mixed color of red and blue is displayed is obtained.

[0012]

EXAMPLE A liquid crystal display device according to an example of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a TFT-LCD of a liquid crystal display device according to an embodiment of the present invention has a first glass substrate (12) and a second glass substrate (19) opposed to each other with a space of several μm therebetween. The liquid crystal layer (16) is formed in the gap. Drain bus lines (15B) which are signal lines and gate bus lines (15A) which are scanning lines are arranged in a matrix on the first glass substrate (12), and TFTs (14) are arranged at their intersections. And a pixel electrode (13) made of a transparent ITO film or the like. Also, the second
There are 3 glass substrates (19) for each pixel electrode.
Corresponding to the first to third counter electrodes (17R, 17G,
17B) and the first to third color filters (18R,
18G, 18B) are provided.

This TFT-LCD is provided with a first polarizing plate (1
It is sandwiched between two polarizing plates, 1) and the second polarizing plate (20),
When white light is made incident, the transmissive liquid crystal display device according to the embodiment of the present invention is obtained. The color filter (18) is composed of three primary colors of R (red), G (green), and B (blue), and is not arranged one by one corresponding to each pixel electrode (13), and the mode is NW (Normally). White) mode.

As described above, according to the liquid crystal display device according to the embodiment of the present invention, one pixel electrode corresponds to one color filter, and the counter electrode is common to all pixels. Differently, as shown in FIG. 1, three kinds of counter electrodes (17R, 17G, 17B) are provided for one pixel.
Are provided, and color filters (18R, 18G, 18B) of three colors are provided corresponding to each.

Therefore, unlike the conventional example in which one pixel corresponds to one color filter and three pixels are required for each pixel, three types of counter electrodes (17) are provided for each pixel.
R, 17G, 17B) are provided, different colors can be independently displayed for one pixel by changing the voltage applied to each counter electrode (17R, 17G, 17B). It becomes possible to compose one picture element with one pixel.

As a result, one pixel can independently display the three primary colors of red, green, and blue. Therefore, the number of TFTs associated with a pixel and the number of gate bus lines or drain bus lines connected to the TFTs can be reduced. The number is small (only 1/3 of the conventional one), high integration and high aperture ratio are possible, and the yield is also improved. Hereinafter, a first driving method of the liquid crystal display device according to the embodiment of the present invention will be described with reference to FIG. This method is a method of displaying only one of the three primary colors using the liquid crystal display device. FIG. 2 is a timing chart illustrating the first driving method of the liquid crystal display device according to the embodiment of the invention.

In FIG. 2, (VG) is a gate voltage applied to the gate of the TFT, (VD) is a drain voltage applied to the drain of the TFT, and (Vt1) is applied to the first counter electrode (17R). Voltage, (Vt2) is the voltage applied to the second counter electrode (17G), and (Vt3) is the third voltage.
This is the voltage applied to the counter electrode (17B). or,
(V1) is a voltage applied to the liquid crystal layer between the first counter electrode (17R) and the first pixel electrode (13) [hereinafter, these are referred to as red pixel regions], and (V2) is the second voltage. Applied to a liquid crystal layer [hereinafter, these are referred to as a green pixel region] between the counter electrode (17G) and the first pixel electrode (13), and (V3) is the third counter electrode (17B). And the first
The voltage (VO) applied to the liquid crystal layer (hereinafter referred to as the blue pixel region) between the pixel electrode (13) and the pixel electrode (13) is sufficiently black when the pixel display is applied to the pixel. Voltage to some extent (hereinafter referred to as offset voltage),
(V) is a normal level voltage [hereinafter referred to as a normal level voltage] suitable for image display, and VB is a normal black level voltage. Note that in the timing chart of FIG. 2, a period from the first ON operation pulse (VG1) of the gate voltage to the fourth ON operation pulse (VG4) is one frame.

According to the first driving method of the liquid crystal display device according to this embodiment, first, as shown in FIG. 2, the first ON operation pulse (VG1) of the gate voltage is synchronized with the rising edge of the first ON operation pulse (VG1). The potential of the counter electrode (VT1) of 1 becomes 0,
The potential between the opposite electrode (VT2) and the third opposite electrode (VT3) becomes −VO, and at the same time, VD having an amplitude voltage of 2 V is applied to the drain bus line.

Therefore, during this period, the voltage (V1) applied to the red pixel area corresponding to red is V, and the voltage (V2) applied to the liquid crystal layer in the second pixel color area and the third pixel. The voltage (V3) applied to the liquid crystal layer in the color region is V + VO
become. Therefore, since V is a normal level voltage and VO is an offset voltage, red is displayed in the red pixel area, but black is displayed in the green pixel area and blue pixel area, and blue and green are displayed. It is not done, so the second O
Until the N operation pulse (VG2) rises, only red is displayed as the whole pixel.

Next, in synchronization with the rising of the second ON operation pulse (VG2) of the gate voltage, the potential of the second counter electrode (VT2) becomes 0, and the first counter electrode (VT).
The potential between 1) and the third counter electrode (VT3) becomes + VO, and at the same time, VD of the amplitude voltage [2VB] is applied to the drain bus line. Therefore, the voltage (V2) applied to the green pixel area during this period is -VB, and the voltage (V1) applied to the red pixel area and the voltage (V3) applied to the blue pixel area are-(VB + VO). become.

Therefore, black display is performed in the red pixel area, the green pixel area and the blue pixel area. Therefore, until the third ON operation pulse (VG3) rises thereafter, no color is displayed in the entire pixel, and black is displayed. Then, the third ON operation pulse (V
G3) in synchronization with the rising edge of the third counter electrode (VT
The potential of 3) becomes 0, the potentials of the first counter electrode (VT1) and the second counter electrode (VT2) become + VO, and at the same time, VD of the amplitude voltage [2VB] is applied to the drain bus line. .

Therefore, the voltage (V3) applied to the blue pixel area during this period is VB, and the voltage (V1) applied to the red pixel area and the voltage (V2) applied to the green pixel area are VB + VO. Become. Therefore, the red pixel area,
Black display is performed in the green pixel area and the blue pixel area. Therefore, until the fourth ON operation pulse (VG4) rises thereafter, the entire pixel is not lit at all and black is displayed.

After that, the fourth ON operation pulse (VG4)
In synchronization with the rising edge of, the drive for the next frame and thereafter is started. Therefore, during the above-mentioned one frame, with respect to the pixel corresponding to the first pixel electrode (13), red lights up in the first section and nothing lights up in the second and third sections and black appears. It will be displayed and red will be lit during this frame.

In this way, only red of the three primary colors can be displayed. In this method, only red is displayed, but by changing the timing, it is possible to display only green and blue by the same method.
Further, according to the liquid crystal display device, it is possible to display not only one of the three primary colors but also a mixed color thereof. The second driving method of the liquid crystal display device will be described below with reference to FIG. This method is a method of displaying a mixed color of three primary colors using the liquid crystal display device.

FIG. 3 is a timing chart for explaining the second driving method of the liquid crystal display device according to the embodiment of the present invention. Note that the reference numerals attached in FIG. 3 are the same as those in FIG. 2, so description thereof will be omitted. First,
As shown in FIG. 3, in synchronization with the rising of the first ON operation pulse (VG1) of the gate voltage, the potential of the first counter electrode (VT1) becomes 0, and the second counter electrode (VT1)
The potential between 2) and the third counter electrode (VT3) becomes -VO, and at the same time, VD having an amplitude voltage of 2 V is applied to the drain bus line.

Therefore, during this period, the voltage (V1) applied to the red pixel area is V, and the voltage (V2) applied to the liquid crystal layer of the second pixel color area and the liquid crystal of the third pixel color area. The voltage (V3) applied to the layer is V + VO. Therefore, since V is a normal level voltage and V + VO is equal to or higher than the offset voltage, red lights up in the red pixel region,
The green pixel area and the blue pixel area become black, and the blue,
Each green color does not light.

Therefore, the second ON operation pulse (V
Until G2) rises, only red lights up for the entire pixel. Next, in synchronization with the rising of the second ON operation pulse (VG2) of the gate voltage, the potential of the second counter electrode (VT2) becomes 0, and the first counter electrode (VT1) and the third counter electrode (VT1) The potential of the electrode (VT3) is + V
It becomes O, and at the same time, VD having an amplitude voltage of 2V is applied to the drain bus line (15B).

Therefore, the voltage (V2) applied to the green pixel area during this period is -V, and the voltage (V1) applied to the red pixel area and the voltage (V3) applied to the blue pixel area are -V. (V + VO). Therefore, since V is a normal level voltage and V + VO is equal to or higher than the offset voltage, the green pixel area lights up in green, but the red pixel area,
The blue pixel area becomes black, and the red and blue colors do not light up.

Therefore, the third ON operation pulse (V
Until G3) rises, only green lights up for the entire pixel. Then, the third ON of the gate voltage
In synchronization with the rising of the operation pulse (VG3), the potential of the third counter electrode (VT3) becomes 0, and the potential of the first counter electrode (VT1) and the second counter electrode (VT2) is + V.
It becomes O, and at the same time, VD of the amplitude voltage [2VB] is applied to the drain bus line.

Therefore, the voltage (V3) applied to the blue pixel area during this period is VB, and the voltage (V1) applied to the red pixel area and the voltage (V2) applied to the green pixel area are VB + VO. That is, all the voltages are higher than the offset voltage. Therefore, black display is performed in the red pixel area, the green pixel area, and the blue pixel area. Therefore,
After that, until the fourth ON operation pulse (VG4) rises, the entire pixel is not lit at all, and black is displayed.

After that, the fourth ON operation pulse (VG4)
In synchronization with the rising edge of, the drive for the next frame and thereafter is started. As described above, for the pixel corresponding to the first pixel electrode (13), red is lit in the first section, green is lit in the second section, and nothing is lit in the third section. Since black is displayed on the screen, red and green are actually switching at high speed, but due to the effects of afterimages, they are not perceived by the naked eye. Since it is recognized as a mixed color, the same effect as displaying a mixed color of red and green by two pixels can be obtained.

Although red and green are mixed in this embodiment, it is also possible to mix red and blue or blue and green in the same manner, and the drain voltage (VD )
It is also possible to display various colors with one pixel by changing. As described above, according to the first and second driving methods of the liquid crystal display device according to the embodiment of the present invention,
In one frame, the red pixel area, the green pixel area, and the blue pixel area corresponding to the three primary colors are sequentially displayed alternately to display colors such as the three primary colors and a mixed color of the three primary colors. Further, by controlling V or VB, multi-gradation display is possible.

Therefore, one pixel can display the three primary colors of red, green, and blue, and by changing the timing for sequentially displaying the red pixel area, the green pixel area, and the blue pixel area, the three primary colors are mixed. It becomes possible to display colors. As a result, unlike a conventional method in which each color is displayed by a combination of a plurality of pixels that can display only a single color (one pixel is composed of three pixels of red, green, and blue), one pixel becomes one pixel. Therefore, it is only necessary to prepare pixels as many as the number of picture elements, and it is possible to display various colors with only one pixel without the need for three times as many pixels as the conventional art. become.

Therefore, the number of pixels and the TFTs associated with the pixels
The number of gate bus lines and drain bus lines connected to the TFT can be reduced accordingly. Therefore, high definition and high aperture ratio can be achieved, and the yield can be improved.

[0035]

As described above, according to the liquid crystal display device of the present invention, the first to third offset signal voltages VO are input to the pixel electrode (13), respectively. Counter electrodes (17R, 17G, 17B) are provided,
The first counter electrode (17R) has a first colored film (18R) that displays red, and the second counter electrode (17G) has a second colored film (18G) that displays green. Third colored film (18B) displaying blue on the counter electrode (17B)
, Each have a pixel provided.

Therefore, unlike the conventional example in which only one color can be displayed corresponding to one pixel electrode (13), that is, one pixel, one pixel can be divided into three regions for use. According to the driving method of the liquid crystal display device of the present invention, the first to third counter electrodes (1
7R, 17G, 17B), the first to third offset signal voltages VO are sequentially input, and the drive control signal (DS) is input to the pixel electrode (13).

Therefore, one pixel can display the three primary colors or a mixed color thereof. Therefore, the number of TFTs attached to a pixel and the number of gate bus lines and drain bus lines connected to the TFTs are small (conventional 1
/ 3), high integration and high aperture ratio are possible, and the yield is also improved.

[Brief description of drawings]

FIG. 1 is an example of a liquid crystal display device according to the present invention.

FIG. 2 is a timing chart illustrating a first driving method of the liquid crystal display device according to the embodiment of the invention.

FIG. 3 is a timing chart illustrating a second driving method of the liquid crystal display device according to the embodiment of the invention.

FIG. 4 is an explanatory diagram of a liquid crystal display device according to a conventional example.

[Explanation of symbols]

11 First Polarizing Plate 12 First glass substrate 13 pixel electrodes 14 TFT 15A gate bus line 15B drain bus line 16 Liquid crystal layer 17 Counter electrode 18 color filters 19 Second glass substrate 20 Second polarizing plate

Claims (4)

(57) [Claims] 1. A plurality of pixel electrodes provided for each pixel on a first transparent substrate, and the plurality of pixel electrodes on an inner surface of a second transparent substrate facing the first transparent substrate via liquid crystal. A plurality of counter electrodes arranged so as to correspond to each of the plurality of counter electrodes, and a plurality of colored films provided to face the plurality of counter electrodes and having different colors from each other with respect to one pixel electrode. A voltage of a level suitable for image display is applied between the counter electrode corresponding to the first color of the plurality of colored films and the pixel electrode, and the counter electrode corresponding to another color is provided. By applying a voltage between the pixel electrode and the pixel electrode such that the display is sufficiently black,
The first color is displayed, and the same operation is performed sequentially for different colors.
And sequentially different colors for one pixel electrode
A liquid crystal display device characterized by being displayed. 2. The liquid crystal display device according to claim 1, wherein the colored film is one of red, green, and blue. 3. The liquid crystal display device according to claim 1, wherein the colored film is formed on a second transparent substrate. 4. The plurality of pixel electrodes are arranged in a matrix, and the counter electrodes are respectively connected in a row direction or a column direction of a matrix of the pixel electrodes, and correspond to the connected counter electrodes. The liquid crystal display device according to claim 1, wherein the colored films have the same color.