JPH0455829A - Color liquid crystal display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color liquid crystal display device using two-layer liquid crystal display elements.

Conventional Technology In a liquid crystal display device that performs color display, strip-shaped or mosaic-shaped color filters are provided on a translucent substrate, alternately for red, green, and blue over the entire display area. 2. Description of the Related Art Liquid crystal display devices in which polarizing plates are arranged on each surface are known. In such a liquid crystal display device, depending on whether the polarizing plate is in a so-called crossed nicole state or in a parallel nickel state, there is a normally white display in which the display is white when the display voltage is cut off and black when the display voltage is applied, and vice versa. You can choose between black and white display.

In the case of a normally black display, the light incident on the liquid crystal display becomes elliptically polarized light due to the optical rotation dispersion phenomenon in the liquid crystal.
Even when the display voltage is cut off, light leaks through the liquid crystal display device, resulting in a decrease in display contrast.

In order to solve this problem, a liquid crystal display device having a two-layer structure including a liquid crystal display element for display and a liquid crystal display element for compensation has been developed.

FIG. 9 is a sectional view of a conventional liquid crystal display device 1. As shown in FIG. The liquid crystal display device 1 includes a liquid crystal display element 2 for display and a liquid crystal display element 3 for compensation, and a pair of glass substrates 4a, 4b of the liquid crystal display element 2 are provided with transparent common electrodes 5a, 5b, 5c and Segment electrodes 6a, 6b, and 6c are formed, and a color filter 7 is formed over the entire surface of the glass substrate 4b.

The color filter 7 has a structure in which, for example, a large number of fine band-shaped filters of red, green, and blue colors are alternately adjacent to each other and formed over almost the entire surface of the glass substrate 4b. An alignment film 8a is formed by covering almost the entire surface of such glass substrates 4a and 4b.
, 8b are formed, for example, a twisted nematic liquid crystal layer 9 is injected therein, and a sealing material 10 is formed around the layer 9.
is sealed.

On the other hand, alignment layers 112a and 12b are formed on the glass substrates] 1a and 11b of the liquid crystal display element 3;
A twisted nematic type liquid crystal layer 13 is injected, and the surrounding area is sealed with a sealing material 14. Deflection plates 15a and 15b are disposed on mutually opposite surfaces of the glass substrates 11a and llb, respectively.

The liquid crystal display element 3 has two functions: (1) a function to compensate for the refractive index difference between normal light and extraordinary light, (2) a function to compensate for optical rotational dispersion in the liquid crystal display element 2, (00 terms and 0 terms) Any one of the functions is set to realize the functions of
The arrangement of the deflection plates 15a and 1.5b is selected so that when 5a and 15b are in a so-called crossed nicol state, a normally black display is obtained, and when they are in a parallel nicol state, a normally white display is obtained.

Here, each region of the color filter corresponding to the segment lights i6a, 6b, and 6c selectively transmits red, green, and blue light, respectively, in a color filter 7R7G.
7B, and the arrangement state of the deflection plates 5a and 1.5b is assumed to be a so-called normally black state. At this time, the application of the display voltage to the segment electrodes 6a, 6b, 6c 7' corresponds to the cutoff state as shown in the states 1, 2, 3, and 4 of Example 1 in Table 1 below, respectively. It is possible to display four colors. Here, Examples 1 and 23 show cases in which segment electrodes 6b and 6c are connected in common, or segment electrodes 6a, 6c are connected in common, or segment electrodes 6a and 6b are connected in common, respectively. Each example allows for four-color display.

(The following is a blank space) Table 1 Problems to be Solved by the Invention In the liquid crystal display device 1 described above, if the arrangement of the polarizing plates 15a15b is changed to a parallel Nicol state, a normally white display is realized instead of a normally black display. be done. In this case, the transmission states of the red, green, and blue transmitted lights are selected as shown in Table 2 below.

Table 2 In such conventional examples, in any of the configurations of Examples 1 to 3 in Table 1, only four colors are displayed in the normally flux display and the normally white display, and the color liquid crystal display There is a problem in that the display diversity of the device is limited.

An object of the present invention is to provide a color liquid crystal display device that can solve the above-mentioned technical problems and greatly expand display diversity.

Means for Solving the Problems The present invention provides a plurality of colors of light that are formed between a pair of light-transmitting substrates at least within a predetermined display area to predetermine transmitted light.
A plurality of color selection members each selected individually, a transparent electrode formed for each color selection member, a first liquid crystal display element with a liquid crystal layer interposed therebetween, and at least the display area between a pair of transparent substrates. A first display signal is applied to each transparent electrode of the second liquid crystal display element and the first liquid crystal display element, which have a transparent electrode and a liquid crystal layer interposed therebetween over a region corresponding to the area.
a first driving means for blocking and selecting transmitted light as one of a plurality of colors; and applying a second display signal to each transparent electrode of a second liquid crystal display element.
and a second driving means for blocking the colored transmitted light from the first liquid crystal display element and selecting one of the plurality of colors or its complementary color.

Function: The color liquid crystal display device according to the present invention is a first color liquid crystal display device for color display.
It is formed into an ellipse including a liquid crystal display element and a second liquid crystal display element for compensation. The first driving means applies/cuts off a display signal to the transparent electrode of the first liquid crystal display element to convert the transmitted light into one of a plurality of colors.
Select. The second driving means applies/cuts off a second display signal to the second liquid crystal display element, and selects the colored transmitted light from the first liquid crystal display element as one of the plurality of colors or its complementary color. This greatly expands the variety of displays.

Embodiment FIG. 1 is a sectional view of a color liquid crystal display device 21 which is an embodiment of the present invention. The liquid crystal display device 21 has two twisted nematic mode liquid crystal elements, a color display liquid crystal element 22 and a compensation liquid crystal element 23.

The color display liquid crystal element 22 has a pair of transparent substrates 24a, 24b made of glass, acrylic resin, etc., and a color filter layer 25 is provided on one surface of the transparent substrate 24a over almost the entire surface.

A plurality of light-transmitting segment electrodes 26 are formed on the color filter layer 25, and the segment electrodes 26
An alignment film 27a is formed on the color filter 25 on which is formed. A plurality of light-transmitting common electrodes 8i28 are formed on one surface of the transparent substrate 24b over an area including at least the segment electrodes 26, and furthermore, on the transparent substrate 24b on which the common electrodes 28 are formed, an oriented electrode is formed. A film 27b is formed. The transparent substrates 24a and 24b are
The surfaces 27a and 27b formed in the orientation 11 are arranged so as to face each other. The twisted nematic liquid crystal layer 29 is injected between the transparent substrates 24a and 24b and sealed with a sealing resin 30.

Polyimide resin is used for the alignment films 27a and 27b. The alignment films 27a and 27b are formed, for example, in a layer N600, and are made of nylon thread woven fabric, for example, so that the alignment direction of liquid crystal molecules is twisted by 90° between the transparent substrates 24a and 24b, forming a levorotatory liquid crystal layer. Rubbed.

In order to keep the distance between the transparent substrates 24a, 24b constant, a plastic spacer (not shown) is sandwiched between the substrates 24a, 24b. With this spacer, the distance between the substrates 24a and 24b is set to, for example, 5 μm. The sealing resin 30 for sealing the liquid crystal layer 29 is, for example, an epoxy resin. For the liquid crystal layer 29, for example, a phenylcyclohexane mixed liquid crystal is selected. Furthermore, cholesteric nonenate is added to this liquid crystal to give it levorotatory properties.The compensating liquid crystal element 23 has transparent substrates 31a and 31b made of glass, acrylic resin, etc.
, 31b are covered with transparent electrodes 42., 31b over almost the entire surface thereof. ．． 43 is formed. Furthermore, it is transparent! 4
Alignment films 32a and 32b are formed on 2.4.3, respectively. Transparent substrates 31a, 31. b is orientation 1B2a,
32b are arranged such that the surfaces on which they are respectively formed face each other. The twisted nematic liquid crystal layer 33 includes transparent substrates 31a, 31. b, and is sealed with a sealing resin 34. Orientation M32a.

32b uses polyimide resin, and the transparent substrate 31a
, 31b, the orientation directions of the liquid crystal molecules are 90 degrees to each other.
It is rubbed to form a twisted, dextrorotatory liquid crystal layer.

For the liquid crystal layer 33, phenylcyclohexane-based mixed liquid crystal was used as in the display liquid crystal element 22 described above. CD-15 (manufactured by Merck & Co., Ltd.) is added to this liquid crystal as a dextrorotatory chiral substance. As in the case of the display liquid crystal element 22 described above, the transparent substrates 31a and 31b are overlapped with a plastic spacer interposed therebetween. Transparent substrates 31a, 31
The spacing between b is selected to be 5 μm, for example.

A deflection plate 35 is provided on the surface of the transparent substrate 24b opposite to the liquid crystal layer 29, and a deflection plate 36 is provided on the surface of the transparent substrate 31a opposite to the liquid crystal layer 33. These deflection plates 35 and 36 are arranged in a crossed Nicols configuration.

Further, a drive circuit 40 having a configuration described later, which is a second drive means for outputting a display signal as described later, is provided to the transparent type 142, 43 of the liquid crystal element 23, and a drive circuit 40 having a configuration described later is provided to the electrodes 26, 28 of the liquid crystal element 22, as described later. A drive circuit 41 having a well-known segment drive circuit FI8 configuration is provided as a first drive means for outputting a display signal to the segment drive circuit. Drive circuit 4.0.4
1 is driven by a signal output from the control circuit 47 as described later.

FIG. 2 is a plan view of the liquid crystal display device 21. FIG. In the liquid crystal display device 21, for example, rectangular segment lines [26 are arranged to form the letter "R", and two such "J" segments are arranged side by side.

FIG. 3 is a plan view of the transparent substrate 24a, and FIG. 4 is a plan view of the transparent substrate 24a.
FIG. 3 is an enlarged cross-sectional view of the vicinity of the color filter 25 in the figure. In this embodiment, for example, the red color filter 25R has a length L.
1, width L2, and a plurality of them are arranged at intervals L3, and are formed into a long belt shape as a whole. The remaining green and blue color filters 25G and 25B are also color filters 25R.
The overall shape is formed into a long strip with the same dimensions and arrangement pitch. In this embodiment, a segment electrode 26a is formed in a band shape on the color filter 25R, and a segment electrode 26a is formed on the color filter 25G. 26b is formed. A light shielding layer 37 made of a metal such as chromium Cr or a synthetic resin material is formed between each of these color filters 25R, 25G, and 25B.

FIG. 5 shows a liquid crystal layer 29 in a color liquid crystal display device 21.
FIG. 6 is a perspective view illustrating the orientation direction of liquid crystal molecules of No. 33, and FIG. 6 is a diagram illustrating the orientation direction of the liquid crystal molecules. In this embodiment, the orientation direction of the liquid crystal molecules 38b closest to the transparent substrate 24b of the liquid crystal layer 29 and the orientation direction of the liquid crystal molecules 38a closest to the transparent substrate 24a are in the left-handed rotation direction as shown in FIG. 6(1). For example, it is twisted 90 degrees. In addition, the liquid crystal molecules 39b closest to the transparent substrate 31b in the liquid crystal element 33 and the liquid crystal molecules 39a closest to the transparent substrate 31a are also twisted by 90 degrees in the left rotation direction, as shown in FIG. 6(1). be. Furthermore, the liquid crystal molecules 38a7B9b are configured to be orthogonal to each other.

The functions and effects of this embodiment, which will be described later, are such that the liquid crystal molecules 38a and 38b in the liquid crystal element 22 are
), the liquid crystal molecules 39b and 39a in the liquid crystal element 23 are twisted in the right-handed direction as shown in FIG. 6(2), and the liquid crystal molecules 38a,
The same effect can be achieved even when 39b are oriented parallel to each other. Furthermore, the liquid crystal molecules 38b and 38a are shown in FIG. 6(3).
The liquid crystal molecules 39 are twisted in the left rotation direction as shown in
The same effect can be achieved even when the liquid crystal molecules 38a, 39a are twisted in the dextrorotary direction as shown in FIG. 6(3), and the liquid crystal molecules 38a, 39b are aligned in mutually orthogonal directions.

FIG. 7 is a block diagram showing an example of the configuration of the drive circuit 40, and FIG. 8 is a timing chart explaining the operation of this embodiment. The drive circuit F1840 (from the control circuit 47) receives the common signal Sc shown in FIG. 8(2) and the liquid crystal element 2.
A selection signal S1 for selecting whether to apply or stop the operating voltage is input to the terminal 3, the common signal Sc is supplied to the transparent electrode 42, and the selection signal S1 and the common signal Sc are connected to an exclusive OR circuit (hereinafter referred to as , EX circuit) 44, and its output is supplied to the transparent electrode 43 as a segment signal Ssl.

Here, the truth table of the EX circuit 44 is shown in Table 3 below.

Table 3 In Table 3 above, the symbols ■ to ■ correspond to the symbols ■ to ■ in FIG. 8 (3). At this time, the applied voltage applied to the liquid crystal element 23 is as shown in FIG. 8 (4), and this applied voltage becomes the driving voltage in the cases of symbols ■ and ■.
In the case of symbols ■ and ■, the operation is stopped. In other words, in the case of symbols ■ and ■, the liquid crystal element 23 is in a non-operating state, and corresponds to normally black.

The color display state in the configuration of the color liquid crystal display device 21 of this embodiment corresponds to the Example 1 column of Table 1 above. At this time, corresponding to the application/cutoff state of the display voltage to the segment electrodes 26a, 26b and 26c, the state 1 in the example 1 column of Table 1 above,
4 as shown in state 92, state 3, and state 4, respectively.
It is possible to display colors. Here, Examples 1 and 2.3 respectively represent cases in which the segment electrodes 26b and 26c are connected in common, or the segment electrodes 26a and 26c are connected in common, or the segment electrodes 26a and 26b are connected in common. In each example, four-color display is possible.

Here, in Example II State 1 in Table 1, both segment electrodes 26a and 26b are in the OFF state, and black is displayed as in column B1 of Example 1 in Table 1.

In example 1 column state 2, the electrode 26a is in the ON state, and the electrode 26a is in the ON state.
6b is in the OFF state, and red is displayed as shown in Table 1. In Table 1 Example 1 Column State 3, the electrode 26a is OFF.
The electrode 26b is in the ON state, and green is displayed as shown in Table 1. In Table 1 Example ll1g1 type B4, electrode 2
Both 6a and 26b are in the ON state, and yellow, which is a mixture of red and green, is displayed as shown in Table 1.

In order to switch the liquid crystal element 23 from a normally black display state to a normally white display state, the selection signal S] is switched at the timings shown by the symbols ■ and @ in Table 2. Here, if red is displayed in the normally black state in the example 1 column state 2 of Table 1, in this embodiment, example 1.191 state 2 of the second table is realized in the normally white display. In other words, light blue, which is a complementary color to red, is displayed.

As described above, in this example, when the liquid crystal element 23 is switched from the normally black display state to the normally white display state, the four colors black, red, green, and yellow that can be displayed in the normally black display state are changed. , white, light blue, pink, and blue. In other words, by controlling the display state of the liquid crystal elements 22 and 23, it is possible to display eight colors. Further, such an effect can be similarly realized in the case of the complement examples of Examples 2 and 3 in Table 1.

As described above, in this embodiment, in the two-layer color liquid crystal display device 21, the number of displayed colors can be doubled compared to the conventional example, and the display diversity can be greatly expanded.

In the embodiment described above, no segment electrode is formed on any one of the color filters 25R, 25G, and 25B as shown in FIG. Connect the color filter 25B shown in Figure 3 to either segment I/electrode 26a or 26b,
It may also be refined to form a corresponding common electrode.

Further, in this embodiment, the color filter layer 25 may be formed over the entire surface including the area where the seal member 30 is arranged between the segment electrodes 26a, 26b, 26c and the glass substrate 24a. 26a, 2
Of course, it may be arranged between 6b, 26c and the orientation M27a.

Effects of the Invention As described above, according to the present invention, by applying/cutting off a display signal to the second liquid crystal display element, the colored transmitted light from the first liquid crystal display element is selected to be that color or its complementary color. Ru. As a result, the variety of colors that can be displayed is increased, and the variety of display can be greatly expanded.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a liquid crystal display device 21 according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG.
4 (2! is an enlarged cross-sectional view of the vicinity of the color filter 25, FIG. 5 is a perspective view explaining the alignment state of liquid crystal molecules, FIG. 6 is a diagram explaining the alignment state of liquid crystal molecules, 7
The figure is a block diagram explaining the refinement of the drive circuit 40゜41,
FIG. 8 is a timing chart explaining the operation of this embodiment, and FIG. 9 is a sectional view of the conventional example. 21...Liquid crystal display device, 22.23...Liquid crystal element,
25... Color filter, 26... Segment electrode,
28...Common electrode, 29.33...Liquid crystal layer, 353
6...Bolarizing plate, 28.29...Liquid crystal molecule, 40,4
1... Drive circuit, 44... EX circuit agent Patent attorney Number of strokes Keiichibetsu 5B Figure 3 27a Figure Figure 1 111) (-111

Claims (1)

[Scope of Claims] A plurality of color selection members formed between a pair of light-transmitting substrates at least within a predetermined display area and each selecting one of a plurality of predetermined colors for transmitted light; A first liquid crystal display element having a transparent electrode and a liquid crystal layer interposed therebetween, and a second liquid crystal display element having a transparent electrode and a liquid crystal layer interposed between a pair of light-transmitting substrates over at least an area corresponding to the display area. Applying a first display signal to the liquid crystal display element and each transparent electrode of the first liquid crystal display element/
a first driving means for blocking and selecting transmitted light as one of a plurality of colors; and applying a second display signal to each transparent electrode of a second liquid crystal display element.
and a second driving means for blocking the colored transmitted light from the first liquid crystal display element and selecting one of the plurality of colors or its complementary color.