JPH0541971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a color liquid crystal display device for displaying images, and more particularly to color display technology of a matrix type liquid crystal display device.

<Background of the invention> Regarding color image display devices using liquid crystals,
This has already been proposed in JP-A-49-57726 and JP-A-49-74438. The former describes an X-Y matrix type display device using striped color filters of three primary colors, and the latter describes an X-Y matrix type display device in which a switching element is provided for each picture element. However, although these examples show the use of stripe-like or mosaic-like color filters of the three primary colors, it is possible to control the drive circuit by making full use of technical means for the arrangement of the three primary color filters and the connection with external circuits. Points of simplification are not specifically detailed.

<Objective of the Invention> An object of the present invention is to provide a color liquid crystal display device incorporating a new and useful color display technology that can be driven by a drive circuit with a simple configuration.

<Description of Structure and Effects> First, a color liquid crystal display device will be explained. A color liquid crystal display device to which the present invention is applied has at least the following elements.

(1) A liquid crystal panel that has a large number of picture elements whose light transmittance or reflectance changes in response to applied voltage.

(2) A colored body provided inside or outside the liquid crystal panel whose position corresponds to each picture element.

(3) Illumination device installed in front or behind the liquid crystal panel.

Only the necessary wavelength components of the light output from the lighting device in (3) above are transmitted through the colored body in (2),
The light enters the liquid crystal panel (1). A color video signal corresponding to the color of the colored body is applied to each picture element of the liquid crystal panel, and the amount of light passing through the liquid crystal panel is controlled in accordance with this signal. Therefore, if such a liquid crystal display device is placed a certain distance away from the human eye and placed in a position that exceeds the resolution of the human eye, the three primary colors of the colored body will not be seen separately, but will be seen as an additive color mixture. Any color television image can be reproduced using the same principle.

The operating modes of the liquid crystal include TN (twisted nematics), GH (guest host), DSM (dynamic scattering),
There are various modes such as phase transition and birefringence, and the present invention is applicable to any mode, but TN and GH give particularly preferable results. In GH, black pigment is used as a so-called black shutter. Details of the operating modes of liquid crystals are described in detail in, for example, "Basics and Applications of Liquid Crystal Electronics" edited by Sasaki, Ohmsha (1979).

An XY matrix method is usually used to control individual picture elements. This is subdivided into the following three methods.

(1) Simple matrix method A liquid crystal cell is constructed by providing striped electrodes on each of two substrates and bonding them orthogonally. A row selection signal is sequentially applied to the row electrodes (electrodes extending in the horizontal direction) and driven in a time division manner.
An image signal is applied to the row electrodes (electrodes extending in the vertical direction) in synchronization with the row selection signal. The intersection of the row electrode and the column electrode forms a picture element, and the optical characteristics of the liquid crystal at that portion change in response to the effective value of the potential difference between the row electrode and the column electrode.

Since the liquid crystal has an effective value response, the number of scanning lines cannot be set too large in terms of cross stroke and dynamic range. In order to overcome these limitations, the following two methods are used.

(2) Addition of non-linear two-terminal element Varistor, MIM (metal/
A method that suppresses crosstalk by adding nonlinear elements such as insulators/metal).

(3) Addition of switching transistor A switching transistor is provided on one substrate corresponding to each picture element, and the liquid crystal of each picture element is driven by the voltage stored in the memory capacitor in a configuration similar to dynamic RAM. . In some cases, the liquid crystal itself can also serve as a memory capacitor. Switching transistor ON/
If the OFF ratio is large, it is possible to drive a large number of picture elements.

As the switching transistor, a thin film transistor (TFT) or a MOS-FET formed on a silicon wafer or the like is used.

Note that the present invention is applicable to any of the above methods (1) to (3).

As the colored body, a color filter is usually provided on the outer or inner surface of the liquid crystal substrate, but it is also possible to use a color polarizing plate. The colored body may be provided on the light source side of the liquid crystal layer, or may be provided on the opposite side. When a color filter is used as the colored body, only about 1/3 of the white light incident on each picture element is used, and the rest is absorbed by the colored body. Furthermore, in the case of a liquid crystal operation mode using a polarizing plate, the amount of light is further reduced to less than half, so a mere reflective display mode without illumination means is too dark to be of practical use. For this reason, light sources such as incandescent bulbs, fluorescent lights, and EL panels are used as lighting means.
Alternatively, a light guide or the like is used to collect ambient light and guide it to the back of the liquid crystal display panel.

Furthermore, when considering application to portable equipment, the power supply capacity is severely constrained, so the luminous efficiency of the light source becomes an important factor.

As described below, the features of the present invention are that, in the above-mentioned color liquid crystal display device, the color arrangement of the picture elements is associated with the extraction of the column electrodes, the color arrangement of the drive circuit is associated with the extraction of the row electrodes, and the drive circuit is simplified. This is an attempt to make the world a better place. Specifically, for example, two of the three primary colors red, green, and blue are alternately arranged on one row electrode, and two colors of other combinations are alternately arranged on the next row electrode. They are arranged periodically with several rows as a repeating unit. Under such an arrangement, when the column electrodes are drawn out vertically and alternately, the color of the picture elements drawn out on each side becomes almost the same color.
In other words, the color arrangement on each column electrode changes from row to row, but in the same row, the column electrode drawn upward becomes one of the two colors, and the same color signal is supplied to the column electrode drawn downward; It becomes the other of the two colors and the same color signal is supplied. Therefore, the circuit configuration such as the color switching circuit is simplified and the manufacturing cost is significantly reduced.

<Embodiment> FIG. 1 is a block diagram of a color liquid crystal display device showing one embodiment of the present invention. FIG. 2 is a block diagram of a conventional color liquid crystal display device shown for comparison. In Figure 2, the liquid crystal display panel
The three colors red (R), green (G), and blue (B) are arranged in order as a color filter on the row electrodes (horizontal electrodes) of the LCP, and in the next row, these three colors are arranged shifted by one. has been done. This arrangement state is repeated sequentially in the row direction, so that each color has the same color lined up diagonally. It is also possible to arrange vertical stripes and horizontal stripes of the same color, but since the spatial resolutions in the vertical and horizontal directions are different, the stripes tend to stand out and are not suitable for practical use. In the conventional configuration, even if each line of column electrodes (vertical electrodes) is drawn out alternately up and down, or all lines are drawn out to one side, all three colors appear equally in different combinations for each line, and all three colors appear in different combinations evenly on the same column electrode. Since the three colors appear in sequence above, the drive circuit must have the following configuration. That is, first, a color image video signal (composite signal) Cs is separated by the chroma circuit 1 into each color signal of a red signal Rs, a green signal Gs, and a blue signal Bs. These color signals are led to line memories 2 corresponding to each color. The line memory 2 includes the same number of sample and hold circuits as the column electrodes, and converts serially sent color signals into parallel signals to be supplied to the column electrodes. Among the signals stored in the line memory 2, only those corresponding to the color arrangement of the picture elements are selected.
It is applied to the column electrodes via the color switching circuit 3. On the other hand, row selection signals are sequentially applied to the row electrodes by a row selection circuit 4 that sequentially outputs signals in response to a synchronization signal Ts. Each picture element belonging to the selected row electrode drives the liquid crystal according to the signal applied to the respective column electrode to change the amount of transmitted light.

On the other hand, in the color liquid crystal display device shown in Fig. 1, two of the three colors red (R), green (G), and blue (B) are arranged alternately on each row electrode, and each column electrode Each line is drawn out alternately in the vertical direction. The color of each picture element on each line drawn out on each side is one color. That is, in the example of FIG. 1, red and green pixels are arranged alternately in the first row, with red picture elements drawn upward and green picture elements drawn downward. In the second row, green and blue pixels are arranged alternately, with green picture elements drawn upward and blue picture elements drawn downward. In the third row, blue and red are arranged alternately, with blue picture elements drawn upward and red picture elements drawn downward. Groups of row electrodes constituting a matrix electrode structure are arranged periodically with these three rows as a repeating unit. In this way, the color drawn to one side changes for each row, but the same color is drawn within the same row. Therefore, the color switching circuit 3 can be arranged before inputting the signal to the line memory 2 to perform color switching, so only one upper and lower line memory 2 is required, and the circuit configuration becomes very simple. . The color image video signal Cs is output as a red signal Rs, a green signal Gs, and a blue signal Bs via the chroma circuit 1, and these are input to the color switching circuit 3. A synchronizing signal Ts is inputted to the color switching circuit 3 and the row selection circuit 4, and in response to this synchronizing signal Ts, color signals are inputted from the color switching circuit 3 to both the upper and lower line memories 2. A predetermined column electrode line is selected in the line memory 2, and a driving voltage is applied to each column electrode line in synchronization with the output of the row selection circuit 4. As described above, matrix driving in the row and column direction is performed in the liquid crystal display panel LCP, and a color image is displayed by additive color mixture corresponding to the hue of each picture element.

As described above, according to the present invention, the color arrangement of the upwardly extending column electrode group and the downwardly extending column electrode group changes sequentially from row to row, but in the same row, each has the same color. Therefore, each has an array of 1
If the same color display signal is supplied to the column electrodes during the line scanning period, matrix type three primary color display becomes possible. This simplifies the drive circuit system and significantly reduces manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a color liquid crystal display device showing one embodiment of the present invention. FIG. 2 is a block diagram of a conventional color liquid crystal display device. 1...Chroma electrode, 2...Line memory, 3...Color switching circuit, 4...Line selection circuit.

Claims (1)

[Claims] 1 A group of color filters that exhibit hues of the three primary colors are
In a color liquid crystal display device in which picture elements arranged in a row-row matrix are arranged periodically for each hue, two of the three primary colors are arranged on row electrodes that connect the picture elements in the row direction. Color filters exhibiting hues of the three primary colors are selected for each row and arranged alternately, and color filters exhibiting hues of the three primary colors are alternately arranged in three colors on column electrodes connecting the picture elements in the column direction. The ends of the column electrodes are sequentially and alternately extended in the vertical arrangement direction and connected to a signal supply circuit, and the column electrodes extending upward are provided with the two colors arranged in each of the row electrodes. A color display signal corresponding to one of the color filters exhibiting one hue is transmitted to the column electrodes extending downward from the color filters exhibiting the two hues arranged in each of the row electrodes. A color liquid crystal display device characterized in that color display signals corresponding to the color filters of the other hue are respectively supplied.