Liquid crystal display device

A liquid crystal display device comprising: a color filter layer having a set of a cyan color filter, a magenta color filter, a yellow color filter for each pixel, each of the color filters being aligned in parallel with each other, a first liquid crystal layer, provided for the color filters, for changing transmittance of light within a first range of wavelengths when an external electric field is applied thereto, and a second liquid crystal layer, provided for the color filters, for changing transmittance of light within a second range of wavelength when an external electric field is applied thereto, the first range of wavelengths being different from the second range of wavelengths. The color filter layer, and first and second liquid crystal layers can be laminated in an arbitrary order. As a result, a liquid crystal display device which realizes a high efficiency of light and bright multi-color display can be provided.

FIELD OF THE INVENTION 
The present invention relates to a liquid crystal display device which 
realizes a multi-color display through additive and subtractive color 
processes. 
BACKGROUND OF THE INVENTION 
Liquid crystal display devices have been used extensively in various 
products including watches, desk calculators, notebook personal computers, 
word processors, and television receivers. 
A so-called TN (Twisted Nematic) mode in which the molecular alignment of 
liquid crystals within a liquid crystal cell is twisted about 90.degree. 
at the initial alignment is known. In the TN mode, a monochrome display is 
obtained by exploiting the optical characteristics of a liquid crystal 
cell sandwiched by a pair of polarizing plates; the optical 
characteristics referred herein mean optical rotation characteristics when 
no voltage is applied to the liquid crystal cell and optical-rotation 
resolution characteristics when a voltage is applied to the same. 
On the other hand, a full-color or multi-color display is obtained by 
exploiting the above-mentioned optical switching characteristics through 
the additive mixture process using a set of red, green, and blue 
microscopic color filters provided in the liquid crystal cell for each 
pixel. The principle of this color display is adopted to a transmission 
type liquid crystal display device such as a liquid crystal television set 
driven by the active-matrix or multiplex-matrix drive. 
An STN (Super Twisted Nematic) mode is extensively used for word 
processor's display devices. In this mode, a cell structure is similar to 
that of the TN mode except that a twist angle of the liquid crystals is 
set in a range between 180.degree. and 270.degree.. More precisely, the 
twist angle of the liquid crystals is set to 90.degree. or more and 
further a set angle of each polarizing plate in a polarizing direction is 
optimized. Accordingly, an abrupt distortion of molecular alignment caused 
by an increase of an applied voltage is reflected on a change of the 
liquid crystals' birefringence. As a result, electro-optic characteristics 
with a sharp threshold can be obtained, which makes the STN mode more 
advantageous and suitable for a liquid crystal display device driven by 
the multiplex-matrix drive. 
However, the STN mode has a drawback that the background of the display 
becomes yellowish green, dark blue, etc. due to the birefringence of the 
liquid crystals. This drawback can be eliminated by a liquid crystal 
display device which enables a monochrome display by correcting colors. 
Colors are corrected by laminating an optical compensation panel or a 
phase difference plate made of polymers such as polycarbonate to an STN 
liquid crystal panel. A full-color or multi-color display in the STN mode 
is obtained based on the same operating principle as that of the TN mode. 
For an application requiring wide viewing angles, a socalled guest-host 
mode is adopted, in which a dye (dichroic dye) whose absorbance of light 
differs in molecular's short and long axis directions is added to the 
liquid crystals. The guest-host mode includes a Heilmeier type which uses 
a polarizing plate, a White-Taylor (phase change) type which does not use 
the polarizing plate, a double-layer type, etc, all of which are based on 
the same operating principle. To be more specific, in this principle, the 
molecular alignment of a dye is controlled indirectly by controlling the 
molecular alignment of the liquid crystals with an application of a 
voltage, and a display is obtained by exploiting a difference of 
absorbance of light in the axis directions of the dye molecules. In 
addition, a color display can be obtained by combining a color filter with 
a guest-host cell containing a dye which absorbs a visible ray in a 
specific range of wavelengths or a dye which shows black. 
A color display obtained by laminating liquid crystal layers containing 
dichroic dyes is disclosed in, for example, International Publication 
WO86/05282 (Japanese Publication Tokuhyosyo No. 62-502780(1987) and U.S. 
Pat. No. 4,953,953. FIG. 15 shows a double-layer type liquid crystal 
display device using the dichroic dyes. Capsules of liquid crystals 51, 
52, and 53 each containing their respective dyes are aligned in parallel 
in one layer, and three pairs of capsules of liquid crystal pixels 
51a.cndot.51b, 52a.cndot.52b, and 53a.cndot.53b are layered in a vertical 
direction, respectively. The colors of the dyes contained in each pair are 
complementary to each other. 
More specifically, assuming that the liquid crystal pixel 51a, 52a, and 53a 
respectively contain a red dye, a green dye, and a blue dye, then the 
liquid crystal pixel 51a is layered atop of the liquid crystal pixel 51b 
which contains a cyan dye, a complementary color to red. Likewise, the 
liquid crystal pixels 52a and 53a are respectively layered atop of the 
liquid crystal pixels 52b and 53b which respectively contain a magenta dye 
and a yellow dye to make pairs of complementary colors, 
green.cndot.magenta and blue.cndot.yellow respectively. A full-color 
display is obtained by driving the capsules of the liquid crystals 
separately while using a set of three dot elements for one pixel. For 
instance, a pixel is displayed in red by applying a voltage only to the 
liquid crystal pixel 51b containing the cyan dye to make the liquid 
crystal pixel 51b transparent, while turning off the electrical connection 
of all the other liquid crystal pixels. 
A triple-layer type liquid crystal display device containing dichroic dyes 
shown in FIG. 16 comprises capsules of three liquid crystal color layers 
56, 57, and 58, and four electrode layers 59, 60, 61, and 62. Each of the 
liquid crystal color layers 56, 57, and 58 contains dyes of their 
respective colors in capsules of the liquid crystal materials: the liquid 
crystal color layers 56, 57, and 58 contain a yellow dye, a cyan dye, and 
a magenta dye, respectively. A color display is obtained by selectively 
applying a predetermined voltage to each liquid crystal color layer. 
In addition, an example of a color liquid crystal display device using a 
dichroic dye and color filters is disclosed in, for example, U.S. Pat. No. 
4,886,343 and Japanese Laid-Open Patent Application No. 6-202099(1994). 
A color liquid crystal display device of U.S. Pat. No. 4,886,343 comprises 
a layer including two color filters of their respective colors aligned in 
parallel, a liquid crystal layer containing a dichroic dye, and another 
liquid crystal layer serving as a shutter. A multi-color display is 
obtained by selectively using the two color filters of their respective 
colors. 
A color liquid crystal display device of Japanese Laid-Open Patent 
Application No. 6-202099(1994) comprises a layer including two color 
filters of their respective colors aligned in parallel, and first and 
second liquid crystal layers each containing their respective dichroic 
dyes. The first and second liquid crystal layers, which are sandwiched by 
a pair of electrodes, have their respective threshold voltages, and a 
multi-color display is obtained by applying a voltage to these liquid 
crystal layers dependently. If a common electrode is additionally provided 
between the first and second liquid crystal layers and voltages are 
applied to these liquid crystal layers separately, more colors will be 
available compared with the above case using a single pair of electrodes. 
An example of a color display obtained using a color polarizer instead of 
the color filters is proposed in Japanese Laid-Open Patent Application No. 
63-264731(1988). A liquid crystal display of this example is of the 
double-layer type and a color polarizer is composed of two layers in 
complementary colors. Here, a color display is obtained by pattering the 
color polarizer for each pixel in each layer. Thus, a resulting monochrome 
display is brighter than the one obtained using a single-layer color 
polarizer; moreover, a black display can be obtained. 
However, each of the above-explained prior arts have following problems. 
The color liquid crystal display device having the parallel red, green, and 
blue color filters reduces the intensity of transmitted light to one-third 
of that of incident light, and thus lowering utilization efficiency of 
light. Although the liquid crystal display device is advantageous in that 
it consumes less power, a color display can not be obtained without using 
a power-consuming back light for this reason, thereby eliminating such an 
advantage of the liquid crystal display device. 
The double-layer type liquid crystal display device, in which one layer 
contains dichroic dyes complementary to those in the other, displays 
white, cyan, magenta, and yellow brighter. However, like the above color 
liquid crystal display device having the parallel red, green, and blue 
color filters, the intensity of the transmitted light is reduced to 
one-third of that of the incident light, thereby producing a dark 
full-color display. 
In contrast, the triple-layer type guest-host liquid crystal display device 
realizes a full-color display using a single pixel. Thus, the utilization 
of light is highly efficient and a resulting full-color display is 
sufficiently bright. However, there remains a technical problem that each 
layer must be driven by individual driving elements which are driven 
separately. In addition, a thickness of the lamination of the three layers 
causes undesirable parallax. 
The layered type liquid crystal display device comprising the layer having 
two parallel color filters and the two liquid crystal layers utilizes 
one-half of the incident light. Thus, the brightness of a resulting color 
display does increase compared with the case where the red, green, and 
blue color filters are aligned in parallel, albeit unsatisfactorily. 
The example which uses the color filters and two liquid crystal layers 
fails to realize a full color display, and if it should succeed, a 
resulting display is dark due to a low utilization efficiency of light. 
The liquid crystal display device using the color polarizer uses the 
polarizing plates and hence reduces the utilization efficiency of the 
incident light to less than one-half. This type of liquid crystal display 
device displays intermediate colors darker in a full-color display 
compared with a monochrome display, and for this reason, is not suitable 
for a full-color display. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a liquid 
crystal display device which can realize a bright multi-color display. 
To fulfill the above object, a liquid crystal display device of the present 
invention is characterized by comprising: 
a filter layer having a set of a cyan color filter, a magenta color filter, 
a yellow color filter for each pixel, each of said color filters being 
aligned in parallel with each other; 
a first liquid crystal layer, provided for said color filters, for changing 
transmittance of light within a first range of wavelengths when an 
external electric field is applied thereto; and 
a second liquid crystal layer, provided for said color filters, for 
changing transmittance of light within a second range of wavelength when 
an external electric field is applied thereto, said first range of 
wavelengths being different from said second range of wavelengths. 
According to the above structure, blue light and green light pass through 
the cyan color filter while blue light and red light pass through the 
magenta color filter and green light and red light pass through the yellow 
color filter. The transmittance characteristics of each filter as above 
are responsible for a color displayed by each pixel. Here, each filter 
utilizes two-thirds of incident light, thereby improving the utilization 
efficiency of light significantly. More specifically, compared with a 
conventional case where the red, green, and blue color filters are aligned 
in parallel, the utilization efficiency of light is increased two-fold, 
and hence making the pixel twice as bright. 
The first and second liquid crystal layers change the transmittance of 
light in different ranges of wavelengths when the external electric fields 
are applied thereto. Thus, the color of transmitted light from the first 
and second liquid crystal layers and color filters, and hence the color 
displayed by each pixel can be changed by controlling the external 
electric field, which enables a multi-color display. 
The above-explained effect can be obtained regardless of the lamination 
order of the filter layer, and first and second liquid crystal layers. In 
other words, since these three layers can be laminated in an arbitrary 
order, the flexibility of a design of the liquid crystal display device 
can be increased at the time of manufacturing. 
When the first and second liquid crystal layers are laminated with the 
filter layer in between, an active element on an intermediate substrate 
(substrate in the center) can be omitted. Thus, the intermediate substrate 
can be made of a thin film member such as a polymeric film. Accordingly, 
the manufacturing costs can be saved compared with a case where the 
intermediate substrate is made of glass. Further, using the thin film 
member such as a polymeric film can make a thinner intermediate substrate. 
As a result, unsatisfactory display caused by parallax can be reduced, 
thereby improving the viewing angle characteristics. 
As has been explained, the liquid crystal display device of the above 
structure can realize a brighter multi-color display compared with a 
conventional liquid crystal display device. 
To fulfill the above object, another liquid crystal display device of the 
present invention is characterized by comprising: 
a first liquid crystal layer for changing transmittance of light within a 
first range of wavelengths when an external electric field is applied 
thereto; 
a second liquid crystal layer for changing transmittance of light within a 
second range of wavelength when an external electric field is applied 
thereto, said first range of wavelengths being different from said second 
range of wavelengths; and 
a reflecting layer having a member that reflects cyan light, magenta light, 
and yellow light of transmitted light from said first and second liquid 
crystal layers, said member being provided for each pixel. 
According to the above structure, the first and second liquid crystal 
layers change the transmittance of light in different ranges of 
wavelengths when the external electric fields are applied thereto. 
Transmitted light from the first and second liquid crystal layers enters 
into the reflecting layer, and cyan light, magenta light, and yellow light 
are reflected by the reflecting member provided for each pixel. In other 
words, two-thirds of incident light can be utilized when the reflecting 
layer is used. Incident light changes its color as it passes through the 
first and second liquid crystal layers and reflects off the reflecting 
layer. Accordingly, the color displayed by each pixel is changed, thereby 
enabling a multi-color display. 
As has been explained, the liquid crystal display device of the above 
structure can realize a brighter multi-color display compared with a 
conventional liquid crystal display device. 
For a fuller understanding of the nature and advantages of the invention, 
reference should be made to the ensuing detailed description taken in 
conjunction with the accompanying drawings.

EMBODIMENTS 
FIRST EMBODIMENT! 
Referring to FIGS. 1 through 5, the following description will discuss an 
embodiment of the present invention. 
As shown in FIG. 1, a liquid crystal display device of the present 
embodiment includes three transparent substrates 1.cndot.2.cndot.3 evenly 
spaced apart, and a liquid crystal layers 4.cndot.5 containing their 
respective dichroic dyes are provided between the transparent substrates 1 
and 2 and the transparent substrates 2 and 3, respectively. Pairs of 
transparent electrodes 7.cndot.8 and transparent electrodes 9.cndot.10 are 
provided so as to sandwich the liquid crystal layer 4 and liquid crystal 
layer 5, respectively. A color filter layer 6 is provided between the 
transparent substrate 2 and transparent electrode 8. 
The color filter layer 6 transmits light in a certain range of wavelengths. 
Although an external electric field develops each time a voltage is 
applied across the transparent electrodes 7 and 8 for an image element, 
the transmittance of the color filter 6 does not change when the external 
electric field is applied thereto. The color filter layer 6 includes a 
cyan color filter 6a, a magenta color filter 6b, and a yellow color filter 
6c, which are aligned in parallel to each other so as to correspond to 
three image elements forming a pixel, respectively. The cyan color filter 
6a transmits blue (purplish blue) light and green light. The magenta color 
filter 6b transmits blue (purplish blue) light and red light, and the 
yellow color filter 6c transmits green light and red light. 
Each of the liquid crystal layers 4 and 5 is divided into two areas, and 
each area contains their respective dichroic dye molecules. For example, 
the liquid crystal layer 4 is divided into an area 4a made of yellow 
guest-host liquid crystals and an area 4b made of magenta guest-host 
liquid crystals. The areas 4a and 4b are provided in such a manner that 
the former corresponds to the cyan color filter 6a and magenta color 
filter 6b while the latter to the yellow color filter 6c. 
Similarly, the liquid crystal layer 5 is divided into an area 5a made of 
magenta guest-host liquid crystals and area 5b made of cyan guest-host 
liquid crystals. The areas 5a and 5b are provided in such a manner that 
the former corresponds to the cyan color filter 6a, while the latter to 
the magenta color filter 6b and yellow color filter 6c. 
Alternatively, the liquid crystal layer 4 may be divided into a first area 
made of green guest-host liquid crystals which corresponds to the cyan 
color filter 6a, and a second area made of red guest-host liquid crystals 
which corresponds to the magenta color filter 6b and yellow color filter 
6c. Also, the liquid crystal layer 5 may be divided into a first area made 
of blue guest-host liquid crystals which corresponds to the cyan color 
filter 6a and magenta color filter 6b, and a second area made of green 
guest-host liquid crystals which corresponds to the yellow color filter 
6c. 
In all the guest-host liquid crystals in the liquid crystal layers 
4.cndot.5, a major axis direction of liquid crystal molecules and that of 
the dichroic dye molecules are substantially parallel to the transparent 
substrate 1 when no voltage is applied across their respective pairs of 
electrodes. Accordingly, light in a specific range of wavelengths is 
absorbed and transmitted light shows a unique color which is determined by 
the dichroic dye molecules. On the other hand, the major axis direction of 
the liquid crystal molecules and that of the dichroic dye molecules are 
substantially orthogonal to the transparent substrate 1 when a voltage is 
applied across their respective pairs of electrodes, thereby allowing 
light to pass through the liquid crystal layers 4.cndot.5. 
A lamination order of the color filter layer 6, liquid crystal layers 4 and 
5 in a vertical direction is arbitrary, and the same effect as to the 
transmittance of light and displayed color can be obtained in any 
lamination order. In the following, a relation among the lamination order, 
viewing angle characteristics, etc. will be explained while referring to 
FIGS. 2(a) and 2(b). Like components are labeled with like numerals with 
respect to FIG. 1 and the explanation of these components is omitted for 
the explanation's convenience. FIG. 2(a) shows a case when an intermediate 
substrate is made of glass, and FIG. 2(b) shows a case when the 
intermediate substrate is made of a polymeric film (thin film member) 
serving as a color filter. Note that the transparent electrodes 7 through 
10 of FIG. 1 are omitted in FIGS. 2(a) and 2(b) to explicitly show the 
position of the layers with respect to each other, and numeral 16 in the 
drawings denotes a reflecting plate. 
In general, two active substrates (substrates on which active elements are 
formed) shown in FIG. 2(a)) are necessary to drive two liquid crystal 
layers. To be more specific, it is necessary to form active elements on 
each of the transparent substrates 2.cndot.3 made of glass to drive the 
liquid crystal layers 4.cndot.5 shown in FIG. 2(a). Here, the color filter 
layer 6 is formed on the transparent substrate 1 of FIG. 2(a) because it 
is difficult to form the color filter layer 6 and active elements on a 
single substrate when the convenience of the manufacturing process is 
considered. 
However, the lamination order is arbitrary and the color filter layer 6 may 
be provided between the liquid crystal layers 4.cndot.5 as shown in FIG. 
2(b). When the layers are laminated in such an order, the active elements 
are formed on the transparent substrate 1 and 3, that is to say, the 
intermediate substrate (the transparent substrate 2) can omit the active 
elements. This means that the transparent substrate 2 can be made of a 
polymeric film or the like to save the manufacturing costs. In addition, 
the intermediate substrate can be thinner if it is made of the polymeric 
film. Thus, unsatisfactory displays caused by parallax can be reduced, 
thereby improving the viewing angle characteristics, which is shown in 
FIGS. 2(a) and 2(b). 
Next, an example of a manufacturing method of the above-structured liquid 
crystal display device will be explained in the following. 
Here, 7059 glass substrates (Corning Inc.) of 1.1 mm thick are used as the 
transparent substrates 1.cndot.3, and ITO films, which will serve as the 
transparent electrodes 7.cndot.10, are formed respectively on the glass 
substrates through sputtering. If the ITO film is too thin, an electrical 
resistance value becomes excessively large, thereby making it impossible 
to obtain a uniform display. In contrast, if the ITO film is too thick, 
not only the transmittance decreases, but also it becomes difficult to 
etch a fine pattern on the ITO film. In view of the foregoing, it is 
adequate to form ITO films of 400 .ANG. to 2000 .ANG. thick, and it is 
preferable to form ITO films of 800 .ANG. to 1500 .ANG. thick. In this 
embodiment, ITO films of 1000 .ANG. thick are formed. 
A relatively thin transparent substrate of 0.7 mm thick is used as the 
transparent substrate 2 to minimize parallax, and a dyed color filter is 
formed on a surface of the transparent substrate 2 as the color filter 6. 
Like those formed on the transparent substrates 1.cndot.3, the ITO films, 
which will serve as the transparent electrodes 8.cndot.9, are formed on 
the two opposing surfaces of the transparent substrate 2 through 
sputtering. 
If the spaces between the transparent substrates are too narrow, light is 
not absorbed sufficiently besides the fact that it is difficult to 
assemble the transparent substrates with such narrow spaces, whereas if 
the spaces are too wide, not only a quite large driving voltage is 
required but also a response speed decreases. In view of the foregoing, it 
is adequate to space apart the transparent substrates 1.cndot.2 and the 
transparent substrates 2.cndot.3 in a range between 3 .mu.m and 15 .mu.m, 
and it is preferable to space apart the transparent substrates 1.cndot.2 
and the transparent substrates 2.cndot.3 in a range between 4 .mu.m and 10 
.mu.m. In this embodiment, the transparent substrates 1.cndot.2 and the 
transparent substrates 2.cndot.3 are spaced apart 7 .mu.m using fiber 
glasses (Nippon Electric Glass Co., Ltd.) as spacers. 
Homeotropic films of the liquid crystal layers 4.cndot.5 are made of 
N,N-dimethyl-N-octadecyl-3-aminopropyltrimethoxysilyl chloride. Liquid 
crystals which serve as the hosts in the liquid crystal layers 4.cndot.5 
are ZLI-4792 (Merck & Co., Inc.), and a cyan dichroic dye, a magenta 
dichroic dye, and a yellow dichroic dye which serve as the guests in the 
liquid crystal layers 4.cndot.5 are SI-497 (Mitsui Toatsu Dyes, Inc.), 
M-618 (Mitsui Toatsu Dyes, Inc.), and M-710 (Mitsui Toatsu Dyes, Inc.), 
respectively. 
If a ratio of a thickness d of the liquid crystal cell to a chiral pitch p, 
which is expressed by d/p, is too small, a contrast ratio decreases, and 
if d/p is too large, a driving voltage increases. In view of the 
foregoing, it is adequate to set d/p in a range between 1 and 5, and it is 
preferable to set d/p in a range between 1.2 and 2. In this embodiment, 
d/p is set to 1.7, and the reason why will be explained in the following 
while referring to FIG. 3. 
As d/p changes, transmittance of light of the liquid crystals changes 
depending on an applied voltage as shown in FIG. 3. In general, a 
reflective type liquid crystal display device operates only under the 
conditions that: 
1) a contrast ratio must be not less than 5; and 
2) a voltage more than 7 Volts must not be applied to the active elements. 
FIG. 3 reveals that an optimal value of d/p satisfying the above 
requirements is 1.7. This is the reason why d/p is set to 1.7 in this 
embodiment. 
If the density of the dichroic dye is too low, light is not absorbed 
sufficiently, and in contrast, if the density of the dichroic dye is too 
high, the dye deposits at a lower temperature. In view of the foregoing, 
it is adequate to set the density of the dichroic dye in a range between 1 
percent by weight and 10 percent by weight, and it is preferable to set 
the density of the dichroic dye in a range between 2 percent by weight and 
5 percent by weight. In this embodiment, the density of the dichroic dye 
is set to 4 percent by weight and it is found that a corresponding 
contrast ratio of transmitted light is 5. 
In this embodiment, the guest-host liquid crystals of two colors are 
injected separately by the following method. To begin with, adhesive 
resists OPSR-5600 (Tokyo Ohka Kogyo Co., Ltd.) are applied to each of two 
glass substrates and the glass substrates are irradiated by ultra-violet 
rays to erect a comb-shaped wall 11 as shown in FIG. 4. Then, the two 
glass substrates are laminated to each other and baked. Subsequently, two 
kinds of liquid crystals 12.cndot.13 containing their respective dichroic 
dyes are injected into the laminated body through liquid crystal injection 
openings 14.cndot.15, respectively. 
Projections and depressions may be formed directly on the transparent 
substrates. For instance, projections in the same shape as the wall 11 of 
FIG. 4 may be formed on plane transparent substrates by the sol-gel 
method, or grooves may be etched into the transparent substrates with 
hydrofluoric acid. Alternatively, the guest-host liquid crystals of two 
colors may be produced based on a printing method using a micro-capsule 
technique. Further, the guest-host liquid crystals of two colors may be 
produced separately by erecting a polymeric wall using a dispenser which 
is used to apply a seal agent. 
Following is an explanation as to how the above-structured liquid crystal 
display device is driven. 
According to the above structure in which the components are layered as 
shown in FIG. 1 and voltages are applied to the liquid crystal layers 
4.cndot.5 separately for each image element, an image element 
corresponding to the cyan color filter 6a, for example, is displayed in 
different colors in the four following cases: 
1) In a case where a voltage is applied to neither of the liquid crystal 
layers 4.cndot.5. 
In this case, blue light is absorbed by the area 4a (yellow or green 
guest-host liquid crystals), and green light having passed through the 
cyan color filter 6a is absorbed by the area 5a (magenta or blue 
guest-host liquid crystals). Thus, the image element as a whole is 
displayed in black. 
2) In a case where a predetermined voltage is applied to the liquid crystal 
layer 4 alone. 
In this case, blue light and green light pass through the area 4a (yellow 
or green guest-host liquid crystals) and the cyan color filter 6a 
sequentially without being absorbed, and the green light alone is absorbed 
by the area 5a (magenta or blue guest-host liquid crystals). Thus, the 
image element as a whole is displayed in blue. 
3) In a case where a predetermined voltage is applied to the liquid crystal 
layer 5 alone. 
In this case, blue light is absorbed by the area 4a (yellow or green 
guest-host liquid crystals), and green light having passed through the 
cyan color filter 6a also passes through the area 5a (magenta or blue 
guest-host liquid crystals). Thus, the image element as a whole is 
displayed in green. 
4) In a case where predetermined voltages are applied to the liquid crystal 
layers 4.cndot.5, respectively. 
In this case, since no light is absorbed by the areas 4a.cndot.5a, the 
image element is displayed in cyan based on blue light and green light 
which have passed through the cyan color filter 6a. 
Likewise, if the components are layered in the same manner as shown in FIG. 
1, an image element corresponding to the magenta color filter 6b is 
displayed in black, blue, red, and magenta in the above four cases, 
respectively, and an image element corresponding to the yellow color 
filter 6c is displayed in black, green, red, and yellow in the above four 
cases, respectively. 
Applications of predetermined voltages to the liquid crystal layers 
4.cndot.5 for each image element and a resulting color displayed by a 
pixel are set forth in TABLEs 1 through 8 below. In TABLEs 1 through 8, 
"ON" indicates that a predetermined voltage is applied to the liquid 
crystal layers 4.cndot.5 for a concerned image element and "OFF" indicates 
otherwise. 
A pixel is displayed in red when the voltages are applied to the liquid 
crystal layers 4.cndot.5 in a combination as set forth in TABLE 1 below. 
To be more specific, when the voltages are applied in such a combination, 
the image element corresponding to the cyan color filter 6a alone is 
displayed in black, while the other image elements corresponding to the 
magenta color filter 6b and yellow color filter 6c are displayed in red. 
Thus, the pixel as a whole is displayed in red. 
TABLE 1 
______________________________________ 
DISPLAY IN RED 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID OFF OFF OFF 
CRYSTAL 
LAYER 4 
LIQUID OFF ON ON 
CRYSTAL 
LAYER 5 
COLOR OF BLACK RED RED 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in green when the voltages are applied to the liquid 
crystal layers 4.cndot.5 in a combination as set forth in TABLE 2 below. 
To be more specific, when the voltages are applied in such a combination, 
the image element corresponding to the magenta color filter 6b alone is 
displayed in black, while the other image elements corresponding to the 
cyan color filter 6a and yellow color filter 6c are displayed in green. 
Thus, the pixel as a whole is displayed in green. 
TABLE 2 
______________________________________ 
DISPLAY IN GREEN 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID OFF OFF ON 
CRYSTAL 
LAYER 4 
LIQUID ON OFF OFF 
CRYSTAL 
LAYER 5 
COLOR OF GREEN BLACK GREEN 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in blue when the voltages are applied to the liquid 
crystal layers 4.cndot.5 in a combination as set forth in TABLE 3 below. 
To be more specific, when the voltages are applied in such a combination, 
the image element corresponding to the yellow color filter 6c alone is 
displayed in black, while the other image elements corresponding to the 
cyan color filter 6a and magenta color filter 6b are displayed in blue. 
Thus, the pixel as a whole is displayed in blue. 
TABLE 3 
______________________________________ 
DISPLAY IN BLUE 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID ON ON OFF 
CRYSTAL 
LAYER 4 
LIQUID OFF OFF OFF 
CRYSTAL 
LAYER 5 
COLOR OF BLUE BLUE BLACK 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in cyan when the voltages are applied to the liquid 
crystal layers 4.cndot.5 in a combination as set forth in TABLE 4 below. 
To be more specific, when the voltages are applied in such a combination, 
the image element corresponding to the cyan color filter 6a is displayed 
in cyan, and the image element corresponding to the magenta color filter 
6b and the one corresponding to the yellow color filter 6c are displayed 
in blue and green, respectively. Since the additive mixture of blue light 
and green light is cyan light, this is equivalent to a case where two 
image elements out of three are displayed in cyan. Thus, the pixel as a 
whole is displayed in cyan. 
TABLE 4 
______________________________________ 
DISPLAY IN CYAN 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID ON ON ON 
CRYSTAL 
LAYER 4 
LIQUID ON OFF OFF 
CRYSTAL 
LAYER 5 
COLOR OF CYAN BLUE GREEN 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in magenta when the voltages are applied to the 
liquid crystal layers 4.cndot.5 in a combination as set forth in TABLE 5 
below. To be more specific, when the voltages are applied in such a 
combination, the image element corresponding to the cyan color filter 6a 
is displayed in blue, and the image element corresponding to the magenta 
color filter 6b and the one corresponding to the yellow color filter 6c 
are displayed in magenta and red, respectively. Since the additive mixture 
of blue light and red light is magenta light, this is equivalent to a case 
where two image elements out of three are displayed in magenta. Thus, the 
pixel as a whole is displayed in magenta. 
TABLE 5 
______________________________________ 
DISPLAY IN MAGENTA 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID ON ON OFF 
CRYSTAL 
LAYER 4 
LIQUID OFF ON ON 
CRYSTAL 
LAYER 5 
COLOR OF BLUE MAGENTA RED 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in yellow when the voltages are applied to the 
liquid crystal layers 4.cndot.5 in a combination as set forth in TABLE 6 
below. To be more specific, when the voltages are applied in such a 
combination, the image element corresponding to the cyan color filter 6a 
is displayed in green, and the image element corresponding to the magenta 
color filter 6b and the one corresponding to the yellow color filter 6c 
are displayed in red and yellow, respectively. Since additive mixture of 
green light and red light is yellow light, this is equivalent to a case 
where two image elements out of three are displayed in yellow. Thus, the 
pixel as a whole is displayed in yellow. 
TABLE 6 
______________________________________ 
DISPLAY IN YELLOW 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID OFF OFF ON 
CRYSTAL 
LAYER 4 
LIQUID ON ON ON 
CRYSTAL 
LAYER 5 
COLOR OF GREEN RED YELLOW 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in black when a voltage is applied to neither the 
liquid crystal layer 4 nor liquid crystal layer 5, so that all the image 
elements are displayed in black as set forth in TABLE 7. 
TABLE 7 
______________________________________ 
DISPLAY IN BLACK 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID OFF OFF OFF 
CRYSTAL 
LAYER 4 
LIQUID OFF OFF OFF 
CRYSTAL 
LAYER 5 
COLOR OF BLACK BLACK BLACK 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in white through the additive mixture process when 
predetermined voltages are applied to both the liquid crystal layer 4 and 
liquid crystal layer 5 for each image element, and the image elements are 
displayed respectively in cyan, magenta, and yellow as set forth in TABLE 
8 below. 
TABLE 8 
______________________________________ 
DISPLAY IN WHITE 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID ON ON ON 
CRYSTAL 
LAYER 4 
LIQUID ON ON ON 
CRYSTAL 
LAYER 5 
COLOR OF CYAN MAGENTA YELLOW 
TRANSMITTED 
LIGHT 
______________________________________ 
As shown in TABLEs 1 through 6, two primary colors out of three pass 
through each color filter, and two image elements out of three are 
displayed in the same color. Thus, a full-color liquid crystal element of 
the present embodiment can double both the utilization efficiency of 
incident light and the brightness compared with a case where the 
conventional red, blue, and green filters are used. 
The transmission type liquid crystal display device of the present 
embodiment using the CMY (cyan, magenta, and yellow) filter and a 
conventional liquid crystal display device using RGB (red, green, and 
blue) filter are compared in terms of the dependency of the utilization 
efficiency on the incident light's wavelengths when the pixel is displayed 
in white, and the result of which is shown in FIG. 5. As shown in FIG. 5, 
the utilization efficiency (brightness) of light in the liquid crystal 
display device of the present embodiment is increased about two-fold 
compared with the conventional liquid crystal display device. In addition, 
the brightness is increased two-fold without impairing the purity of each 
color when the pixels are displayed individually in red, green, blue, 
cyan, magenta, yellow, and white. 
The lamination order within the image elements in a vertical direction is 
arbitrary in this embodiment. Thus, when the guest-host liquid crystals 
are a combination of cyan, magenta, and yellow, or a combination of red, 
green, and yellow, the liquid crystal display device can be of a simple 
structure having the guest-host liquid crystals of two colors in each 
layer as shown in FIG. 1. 
In this embodiment, the liquid crystal layers 4.cndot.5 transmit light of 
different ranges of wavelengths, and voltages are applied to the liquid 
crystal layers 4.cndot.5 separately. Thus, the liquid crystal layers 
4.cndot.5 can be made relatively easy using a comb-shaped cell, and a 
resulting display is fairy bright. 
A case where the voltages are applied to the liquid crystal layers 
4.cndot.5 separately for each image element was explained in the present 
embodiment. However, the present invention is not limited to the above 
case, and the voltages may be applied to the liquid crystal layers 
4.cndot.5 simultaneously for each image element if the liquid crystal 
layer 4 is laminated adjacently to the liquid crystal layer 5. This 
structure can be realized by providing a pair of electrodes which sandwich 
the liquid crystal layers 4.cndot.5 and applies voltages simultaneously to 
the liquid crystal layers 4.cndot.5 to change the transmittance of each 
layer in response to the magnitudes of the applied voltages. When the 
voltages are applied to the liquid crystal layers 4.cndot.5 simultaneously 
for each image element, a simple, bright, multi-color liquid crystal 
display device can be realized, although the number of available colors is 
reduced. 
In the present embodiment, the guest-host mode of the White-Taylor type 
with the homeotropic surface treatment was explained. However, the present 
invention is not limited to this specific mode, and a White-Taylor mode 
with the homogeneous surface treatment, or other guest-host modes may be 
used as well. Alternatively, polymer dispersing type liquid crystal 
display device such as a PDLC may be used. 
In the present embodiment, the color filter layer 6 is formed on the 
transparent substrate 2. However, the present invention is not limited to 
this specific structure, and the color filter layer 6 can be laminated in 
any order within one image element; the color filter layer 6 may be formed 
on a lower surface of the transparent substrate 1 or transparent substrate 
2, or on an upper surface of the transparent substrate 3. Note that the 
function and effect of the color filter layer 6 are the same in any 
lamination order. In addition, the transparent substrate 2 can be replaced 
with a color filter layer. 
In the present embodiment, a dyed color filter was used as the color 
filter. However, the color filter is not limited to the dyed color filter, 
and a dye distributed filter or printed color filter may be used. 
Alternatively, a liquid crystal layer which shows cyan, magenta, and 
yellow may be used as the color filer layer. 
In the present embodiment, a transmission type liquid crystal display 
device was explained as an example, but the present invention is not 
limited to the transmission type liquid crystal display device. The 
present invention can be applied to a reflective type liquid crystal 
display device if a reflecting plate is additionally provided. In this 
case, incident light on the reflecting plate, which is in effect the 
transmitted light from the color filter layer 6 and liquid crystal layers 
4.cndot.5, is reflected by the reflecting plate, and enters into the color 
filter layer 6 to pass through the color filters other than the one it has 
already passed through, thereby making it possible to further improve the 
utilization efficiency of light. Also, for example, if a reflecting 
electrode (not shown) made of Al is formed on the transparent substrate 3, 
the reflecting electrode can also serve as the reflecting plate, which is 
known as an inter-cell reflecting electrode structure. 
SECOND EMBODIMENT! 
Referring to FIGS. 6 and 7, the following description will discuss another 
embodiment of the present invention. Like components are labelled with 
like numerals with respect to the first embodiment and the explanation of 
these components is not repeated for the explanation's convenience. 
A liquid crystal display device of the present embodiment is of a 
reflective type, and as shown in FIG. 6, the reflective type liquid 
crystal display device is different from the transmission type liquid 
crystal display device of the first embodiment in that: a dielectric 
mirror layer 21 which reflects cyan light, magenta light, and yellow light 
is provided on a lower surface of the transparent electrode 10 instead of 
the color filter layer 6 which transmits cyan light, magenta light, and 
yellow light; and a photo-absorbing layer 26 which absorbs incident light 
is provided between the dielectric mirror layer 21 and transparent 
substrate 3. The dielectric mirror layer 21 comprises a dielectric mirrors 
21a, 21b, and 21c which correspond to three image elements in one pixel, 
respectively and reflect cyan light, magenta light, and yellow light, 
respectively. 
The dielectric mirrors 21a.cndot.21b.cndot.21c of the dielectric mirror 
layer 21 are made of a lamination of an SiO.sub.2 layer having a 
refractive index of about 1.46 and a TiO.sub.2 layer having a refractive 
index of about 2.1. Each of the SiO.sub.2 layer and TiO.sub.2 layer 
satisfies a relation as follows: 
EQU n.cndot.d=.lambda.4 
where n is the refractive index of each layer, d is a thickness of each 
layer, and .lambda. is a wavelength of light reflected by each mirror. 
According to the above structure, if cyan light enters the dielectric 
mirror 21a when the voltages are applied to both the liquid crystal layers 
4.cndot.5, the cyan light is reflected toward the liquid crystal layers 
4.cndot.5 again. On the other hand, red light passes through the 
dielectric mirror 21a and enters the photo-absorbing layer 26 to be 
absorbed therein. The rest of the operation is identical with the first 
embodiment except that the order of the liquid crystal layers 4.cndot.5 is 
reversed, and the explanation thereof is omitted herein. Since the 
dielectric mirror layer 21 per se serves as the reflecting plate, the 
reflecting type liquid crystal display device of the present embodiment 
can be of a simpler structure compared with a case where a liquid crystal 
display device structured as shown in FIG. 1 is changed into the 
reflective type by additionally providing a reflecting plate. 
Also, each image element, and hence a pixel is displayed in a specific 
color under the predetermined state of the liquid crystal layers 4.cndot.5 
(i.e., whether they are turned on or not) in the same manner as the first 
embodiment, and the explanation thereof is omitted. 
In the following, a transmission type liquid crystal display device using a 
dielectric mirror will be explained while referring to FIG. 7. Like 
components are labelled with like numerals with respect to FIGS. 1 and 6, 
and the explanation of these components is not repeated. 
The transmission type liquid crystal display device of FIG. 7 is different 
from its counterpart of the first embodiment in that: 
1) a dielectric mirror layer 22 comprising dielectric mirrors 22a, 22b, and 
22c which respectively reflect red light, green light, and blue light for 
three image elements in one pixel is provided on a lower surface of the 
transparent substrate 10; 
2) a back light 39 is provided below the transparent substrate 3; and 
3) a substrate 30 having a mirror 40 on the top surface thereof is provided 
below the back light 39. 
According to the above structure, cyan light, magenta light, and yellow 
light pass through the dielectric mirrors 22a, 22b, and 22c, respectively, 
and thus forming a transmission type liquid crystal display device. 
However, since the dielectric mirror layer 22 reflects external light, the 
cyan color filter 6a, magenta color filter 6b, and yellow color filter 6c 
must be provided above the dielectric mirrors 22a.cndot.22b.cndot.22c 
reflecting red, green, and blue light, respectively. In this case, 
therefore, the structure becomes complicated; however, since light coming 
out from the back light 39 and reflected by the dielectric mirror layer 22 
is reflected again by the mirror 40 provided below the back light 39 and 
passes through the dielectric mirror of another image element, thereby 
further enhancing the utilization efficiency of light. 
If one layer is to contain liquid crystals of two respective colors, such a 
layer can be produced in the same manner as the first embodiment, and the 
explanation thereof is omitted herein. 
Only the basic structure was explained in the first and second embodiments, 
but in practice, it is preferable to provide a thin film transistor or 
two-terminal element such as an MIM (metal-insulator metal) element and a 
varistor on the transparent substrates 1.cndot.3 when assembling a liquid 
crystal panel to display an image or the like. In the first and second 
embodiments, a glass plate of 0.7 mm thick was used as the transparent 
substrate provided between the two liquid crystal layers; however, if the 
parallax is taken into consideration, it is preferable to use a glass 
substrate of 0.3 mm to 0.7 mm thick. Further, a polymeric film substrate 
or the like can be used as the transparent substrate. The parallax can be 
eliminated completely when a fiber plate, SELFOC lens, micro-lens, or the 
like is used on the transparent substrate. 
THIRD EMBODIMENT! 
As shown in FIG. 8, a liquid crystal display device of the present 
embodiment includes a liquid crystal layer 44 containing dichroic dye 
molecules between transparent substrates 41.cndot.43. A color filter 46 is 
provided between the transparent substrate 41 and a transparent electrode 
47 as a layer for transmitting or reflecting light in a certain range of 
wavelengths. As shown in the drawing, the color filter 46 includes a cyan 
color filter 46a, a magenta color filter 46b, and a yellow color filter 
46c, each corresponding to one image element. The liquid crystal layer 44 
includes droplets 44a.cndot.44b of different sizes, which are made of 
liquid crystals and contain their respective dichroic dyes. The larger 
droplets 44a contain a cyan dichroic dye while the smaller droplets 44b 
contain a red dichroic dye. 
According to the present embodiment, two kinds of droplets 44a.cndot.44b 
containing the liquid crystals are included in a single liquid crystal 
layer 44. Thus, unlike the first and second embodiments, it is not 
necessary to separate the liquid crystals within the layer, thereby making 
it possible to slush the steps in the manufacturing process. 
A size of the droplets depends on a threshold of a voltage driving the 
liquid crystals (a voltage applied across the transparent electrodes 47 
and 50). The liquid crystals within the larger droplets 44a are driven by 
a low voltage, and the liquid crystals within the smaller droplets 44b are 
driven when the voltage is increased. Accordingly, although the cyan color 
filter 46a displays only black and cyan, the magenta color filter 46b can 
display black, blue, and magenta while the yellow color filter 46c can 
display black, green, and yellow. 
As has been explained, the liquid crystal display device of the present 
embodiment is of a simple structure using a single liquid crystal layer 
44. Thus, the number of elements controlling the drive of the liquid 
crystal layer can be reduced significantly compared with a case where two 
liquid crystal layers are used. Also, the present embodiment realizes a 
multi-color display device which can display white by utilizing two-thirds 
of incident light. 
A combination of colors of the droplets 44a and 44b is not limited to the 
one specified as above, and any combination of complementary colors is 
available. Also, one liquid crystal layer does not necessarily contain two 
kinds of droplets, and two liquid crystal layers each containing their 
respective kinds of droplets may be laminated to each other. In this case, 
however, the structure complicates and the number of the elements 
controlling the liquid crystal layers increases. 
In this embodiment, the droplets 44a.cndot.44b of different sizes were 
used, so that the droplets 44a.cndot.44b will have their respective 
thresholds, but the present invention is not limited to this structure. 
The liquid crystal display device may be of double-layer structure in 
which each layer contains liquid crystals having different thresholds. 
To explain the simplest structure, the liquid crystals of the present 
embodiment show the same color regardless of the colors of the color 
filters. However, liquid crystals which show different colors depending on 
the colors of the color filters may be used. For example, if a combination 
of cyan, magenta, and yellow color filters are layered like the first and 
second embodiments, more colors will be available. 
Also, like the second embodiment, the liquid crystal display device of the 
present embodiment can be changed to a reflective type or transmission 
type which uses a dielectric mirror. 
FOURTH EMBODIMENT! 
Referring to FIGS. 5, 9, and 10, the following description will discuss 
still another embodiment of the present invention. Like components are 
labelled with like numerals with respect to the first embodiment and the 
explanation of these components is not repeated for the explanation's 
convenience. 
Unlike the counterpart of the first embodiment which enables multi-color 
display using dichroic dyes in the liquid crystal layers 4.cndot.5, a 
liquid crystal display device of the present embodiment displays colors by 
exploiting a birefringence effect. In such a liquid crystal display 
device, the liquid crystal layers are sandwiched by a pair of polarizing 
plates to render the transmitted light various colors as a result of an 
interference effect between an ordinary wave and an extraordinary wave. 
The liquid crystal display device of the present embodiment shown in FIG. 9 
is of a reflecting type, and compared with the counterpart of the first 
embodiment, a substrate 63 having a linear polarizability is provided 
instead of the transparent substrate 2, a liquid crystal layer 60 made of 
homogeneous nematic liquid crystal layers is provided between the 
transparent substrates 1 and 63 instead of the liquid crystal layer 4, and 
a liquid crystal layer 60 made of homogeneous nematic liquid crystals is 
provided between the transparent substrates 63 and 3 instead of the liquid 
crystal layer 5. Further, a linear polarizing plate 62 is placed on an 
outer surface side (upper side in the drawing) of the transparent 
substrate 1, while a reflecting plate 64 is placed on an outer surface 
side (lower side in the drawing) of the transparent substrate 3. A plain 
transparent substrate and a liner polarizing plate may be combined to 
serve as the transparent substrate 63 having the liner polarizability. 
The initial alignment directions of the liquid crystal layers 60.cndot.61 
are controlled by the rubbing method so that they match. The polarizing 
axis of the linear polarizing plate 62 is set to 45.degree. with respect 
to the initial alignment direction, and the polarizing axis of the 
transparent substrate 63 having the linear polarizability is set to 
-45.degree. with respect to the initial alignment direction, assuming that 
a direction in which the rubbing method was applied is 0.degree. and a 
clockwise direction is positive. 
According to the above structure, the liquid crystal layers 60.cndot.61 
show interference colors due to birefringence interference, and the 
interference colors can be changed by changing the retardation 
(.DELTA.n.cndot.d) of the liquid crystals using the voltages applied from 
pairs of the transparent electrodes 7.cndot.8 and 9.cndot.10. 
In other words, an applied voltage is controlled in such a manner that 
areas corresponding to the cyan color filter 6a and magenta color filter 
6b in the liquid crystal layer 60 will show white-yellow, and another 
applied voltage is controlled in such a manner that an area corresponding 
to the yellow color filter 6c in the liquid crystal layer 60 will show 
white-magenta. 
Likewise, an applied voltage is controlled in such a manner that an area 
corresponding to the cyan color filter 6a in the liquid crystal layer 61 
will show white-magenta, and another applied voltage is controlled in such 
a manner that areas corresponding to the magenta color filter 6b and 
yellow color filter 6c in the liquid crystal layer 61 will show 
white-cyan. 
Since the colors shown by the liquid crystal layers 60.cndot.61 are 
determined by the retardation (.DELTA.n.cndot.d) of the liquid crystals as 
shown in FIG. 10, the voltages applied to the liquid crystal layers 
60.cndot.61 are controlled in such a manner that the liquid crystals will 
have a retardation (.DELTA.n.cndot.d) corresponding to a desired color. To 
be more specific, to display a desired color, voltages are applied to the 
liquid crystal layers 60.cndot.61, so that the retardation of the liquid 
crystals will be in a range specified as follows: 
______________________________________ 
DESIRED COLOR RETARDATION 
______________________________________ 
White 100 nm to 200 nm 
Yellow 250 nm to 350 nm 
Magenta 450 nm to 550 nm 
Cyan 650 nm to 750 nm 
______________________________________ 
In the following, the colors displayed by the liquid crystal layers 
60.cndot.61 for each image element and a resulting color displayed by a 
pixel are set forth in TABLEs 9 through 16 below. 
A pixel is displayed red when the applied voltages to the liquid crystal 
layers 60.cndot.61 are controlled in such a manner that the liquid 
crystals have a combination of retardation for the interference colors as 
set forth in TABLE 9 below. To be more specific, the image element 
corresponding to the cyan color filter 6a alone is displayed in black, 
while the image elements corresponding to the magenta color filer 6b and 
yellow color filter 6c are displayed in red. Thus, the pixel as a whole is 
displayed in red. 
TABLE 9 
______________________________________ 
DISPLAY IN RED 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID YELLOW YELLOW MAGENTA 
CRYSTAL 
LAYER 60 
LIQUID MAGENTA WHITE WHITE 
CRYSTAL 
LAYER 61 
COLOR OF BLACK RED RED 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in green when the applied voltages to the liquid 
crystal layers 60.cndot.61 are controlled in such a manner that the liquid 
crystals have a combination of retardation for the interference colors as 
set forth in TABLE 10 below. To be more specific, the image element 
corresponding to the magenta color filter 6b alone is displayed in black, 
while the other two image elements corresponding to the cyan color filer 
6a and yellow color filter 6c are displayed in green. Thus, the pixel as a 
whole is displayed in green. 
TABLE 10 
______________________________________ 
DISPLAY IN GREEN 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID YELLOW YELLOW WHITE 
CRYSTAL 
LAYER 60 
LIQUID WHITE CYAN CYAN 
CRYSTAL 
LAYER 61 
COLOR OF GREEN BLACK GREEN 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in blue when the applied voltages to the liquid 
crystal layers 60.cndot.61 are controlled in such a manner that the liquid 
crystals have a combination of retardation for the interference colors as 
set forth in TABLE 11 below. To be more specific, the image element 
corresponding to the yellow color filter 6c alone is displayed in black, 
while the other two image elements corresponding to the cyan color filer 
6a and magenta color filter 6b are displayed in blue. Thus, the pixel as a 
whole is displayed in blue. 
TABLE 11 
______________________________________ 
DISPLAY IN BLUE 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID WHITE WHITE MAGENTA 
CRYSTAL 
LAYER 60 
LIQUID MAGENTA CYAN CYAN 
CRYSTAL 
LAYER 61 
COLOR OF BLUE BLUE BLACK 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in cyan when the applied voltages to the liquid 
crystal layers 60.cndot.61 are controlled in such a manner that the liquid 
crystals have a combination of retardation for the interference colors as 
set forth in TABLE 12 below. To be more specific, the image elements 
corresponding to the cyan color filter 6a, magenta color filter 6b, and 
yellow color filter 6c are displayed in cyan, blue, and green, 
respectively. Since the additive mixture of blue light and green light is 
cyan light, this is equivalent to a case where two image elements out of 
three are displayed in cyan. Thus, the pixel as a whole is displayed in 
cyan. 
TABLE 12 
______________________________________ 
DISPLAY IN CYAN 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID WHITE WHITE WHITE 
CRYSTAL 
LAYER 60 
LIQUID WHITE CYAN CYAN 
CRYSTAL 
LAYER 61 
COLOR OF CYAN BLUE GREEN 
TRANSMITTED 
LIGHT 
______________________________________ 
A pixel displays magenta when the applied voltages to the liquid crystal 
layers 60.cndot.61 are controlled in such a manner that the liquid 
crystals have a combination of retardation for the interference colors as 
set forth in TABLE 13 below. To be more specific, the image elements 
corresponding to the cyan color filter 6a, magenta color filter 6b, and 
yellow color filter 6c are displayed in blue, magenta, and red, 
respectively. Since the additive mixture of blue light and red light is 
magenta light, this is equivalent to a case where two image elements out 
of three are displayed in magenta. Thus, the pixel as a whole is displayed 
in magenta. 
TABLE 13 
______________________________________ 
DISPLAY IN MAGENTA 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID WHITE WHITE MAGENTA 
CRYSTAL 
LAYER 60 
LIQUID MAGENTA WHITE WHITE 
CRYSTAL 
LAYER 61 
COLOR OF BLUE MAGENTA RED 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in yellow when the applied voltages to the liquid 
crystal layers 60.cndot.61 are controlled in such a manner that the liquid 
crystals have a combination of retardation for the interference colors as 
set forth in TABLE 14 below. To be more specific, the image elements 
corresponding to the cyan color filter 6a, magenta color filter 6b, and 
yellow color filter 6c are displayed in green, red, and yellow, 
respectively. Since the additive mixture of green light and red light is 
yellow light, this is equivalent to a case where two image elements out of 
three will be displayed in yellow. Thus, the pixel as a whole is displayed 
in yellow. 
TABLE 14 
______________________________________ 
DISPLAY IN YELLOW 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID YELLOW YELLOW WHITE 
CRYSTAL 
LAYER 60 
LIQUID WHITE WHITE WHITE 
CRYSTAL 
LAYER 61 
COLOR OF GREEN RED YELLOW 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in black when the applied voltages to the liquid 
crystal layers 60.cndot.61 are controlled in such a manner that the liquid 
crystals have a combination of retardation for the interference colors as 
set forth in TABLE 15 below. To be more specific, the image elements 
corresponding to the cyan color filter 6a, magenta color filter 6b, and 
yellow color filter 6c are all displayed in black. 
TABLE 15 
______________________________________ 
DISPLAY IN BLACK 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID YELLOW YELLOW MAGENTA 
CRYSTAL 
LAYER 60 
LIQUID MAGENTA CYAN CYAN 
CRYSTAL 
LAYER 61 
COLOR OF BLACK BLACK BLACK 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in white when the applied voltages to the liquid 
crystal layers 60.cndot.61 are controlled in such a manner that the liquid 
crystals have a combination of retardation for the interference colors as 
set forth in TABLE 16 below. To be more specific, the image elements 
corresponding to the cyan color filter 6a, magenta color filter 6b, and 
yellow color filter 6c are displayed in cyan, magenta, yellow, 
respectively, which turn into white when additively mixed. 
TABLE 16 
______________________________________ 
DISPLAY IN WHITE 
FILTER 6a 
FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID WHITE WHITE WHITE 
CRYSTAL 
LAYER 60 
LIQUID WHITE WHITE WHITE 
CRYSTAL 
LAYER 61 
COLOR OF CYAN MAGENTA YELLOW 
TRANSMITTED 
LIGHT 
______________________________________ 
As shown in TABLEs 9 through 14, two primary colors out of three pass 
through each color filter, and two image elements out of three are 
displayed in the same color. Thus, like the first embodiment, a full-color 
liquid crystal display device of the present embodiment can double not 
only the utilization efficiency of incident light but also the brightness 
compared with a case where the conventional red, blue, and green filters 
are used. 
The transmission type liquid crystal display device of the present 
embodiment using the CMY filter and a conventional liquid crystal display 
device using RGB filter are compared in terms of the dependency of the 
utilization efficiency of light on the incident light's wavelength when 
the pixel is displayed in white, and the result of which is shown in FIG. 
5. As shown in FIG. 5, the utilization efficiency of light (brightness) in 
the liquid crystal display device of the present embodiment is increased 
two-fold compared with the conventional liquid crystal display device as 
was in the first embodiment. 
In addition, the brightness is increased two-fold without impairing the 
purity of each color when the pixels are displayed in red, green, blue, 
cyan, magenta, yellow, and white individually. 
Since the homogeneous nematic liquid crystals are used in the liquid 
crystal layers 60.cndot.61, light can be double-refracted in a more 
idealistic manner compared with a case where the homeotropic nematic 
liquid crystals are used. As a result, multi-color display exploiting the 
birefringence effect can be realized more efficiently, thereby 
facilitating a color display. 
The liquid crystal display device explained in the present as an example 
was of a reflective type. However, the present invention is not limited to 
the reflective type and the present invention may be applicable to a 
transmission type as well. 
FIFTH EMBODIMENT! 
Referring to FIG. 5 and FIGS. 11 through 13, the following description will 
discuss still another embodiment of the present invention. Like components 
are labelled with like numerals with respect to the first and fourth 
embodiments and the explanation of these components is not repeated for 
the explanation's convenience. 
Unlike the fourth embodiment in which a multi-color display was obtained by 
exploiting the birefringence effect realized by the homogeneous alignment 
of the nematic liquid crystals, a multi-color display is obtained by 
exploiting the birefringence effect realized by the twisted nematic liquid 
crystals in this embodiment. 
A liquid crystal display device of the present embodiment is of a 
transmission type, and as shown in FIG. 11, a liquid crystal layer 70 made 
of twisted nematic liquid crystals twisted 240.degree. is provided between 
the transparent substrates 1 and 63 instead of the liquid crystal layer 60 
used in the counterpart of the fourth embodiment, and a liquid crystal 
layer 71 made of twisted nematic liquid crystals twisted 240.degree. is 
provided between the transparent substrates 63 and 3 instead of the liquid 
crystal layer 61 used in the counterpart of the fourth embodiment. Also, a 
liner polarizing plate 72 is provided on an outer surface (lower surface 
in the drawing) side of the transparent substrate 3 instead of the 
reflecting plate 64. 
The liquid crystal layer 70 is divided into two areas 70a and 70b, and the 
liquid crystals in each area are aligned in different directions. That is 
to say, the liquid crystals in each area are aligned in different 
directions, so that different colors will be displayed. The alignment of 
the liquid crystals in each area is controlled separately using the mask 
rubbing method as the manufacturing method. 
In contrast, the liquid crystal layer 71 is not divided, and the liquid 
crystals therein are aligned in a single direction. Thus, different colors 
can be displayed when the retardation and optical rotatory dispersion in 
each image element area are changed by controlling the applied voltages to 
the image element areas. 
In the above-structured liquid crystal display device, each of the liquid 
crystal layers 70.cndot.71 shows interference colors due to the 
birefringence interference and optical rotatory dispersion, and the 
interference colors can be changed when the retardation and optical 
rotatory characteristics are varied by applying voltages from pairs of the 
transparent electrodes 7.cndot.8 and 9.cndot.10. More specifically, bright 
color display in white, black, red, green, blue, cyan, magenta, and yellow 
can be obtained by combining the liquid crystal layers 70 and 71 having 
the color display characteristics set forth in TABLE 17 below with the 
cyan color filter 6a, magenta color filter 6b, and yellow color filter 6c. 
TABLE 17 
__________________________________________________________________________ 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
__________________________________________________________________________ 
LC B:TRANSMITTABLE 
B:CHANGEABLE 
B:UNMENTIONED 
LAYER 
G:CHANGEABLE 
G:UNMENTIONED 
G:CHANGEABLE 
70 R:UNMENTIONED 
R:TRANSMITTABLE 
R:TRANSMITTABLE 
LC B:CHANGEABLE 
B:TRANSMITTABLE 
B:UNMENTIONED 
LAYER 
G:TRANSMITTABLE 
G:UNMENTIONED 
G:TRANSMITTABLE 
71 R:UNMENTIONED 
R:CHANGEABLE 
R:CHANGEABLE 
__________________________________________________________________________ 
In TABLE 17, capital letters B, G, and R stand for blue, green, and red, 
respectively, and "transmittable" means the liquid crystal layer always 
transmits light of a concerning color, "changeable" means whether the 
liquid crystal layer transmits light of the concerning color or not can be 
changed, and "unmentioned" means whether the concerned color passes 
through the liquid crystal layer or not is negligible. 
To render the color display characteristics set forth in TABLE 17 to the 
liquid crystal layers 70.cndot.71, the properties of the liquid crystal 
layers 70.cndot.71 are specified as set forth in TABLE 18 below, assuming 
that the polarizing direction of the polarizing plate 62 is 0.degree. and 
a clockwise direction is positive. 
TABLE 18 
__________________________________________________________________________ 
FILTER 6a 
FILTER 6b 
FILTER 6c 
(CYAN) 
(MAGENTA) 
(YELLOW) 
__________________________________________________________________________ 
70 
POLARIZING PLATE 62'S POLARIZING DIRECTION 
0.degree. 
0.degree. 
0.degree. 
LC'S ALIGNMENT DIRECTION ON SUBSTRATE 1 
-90.degree. 
-130.degree. 
-130.degree. 
LC'S ALIGNMENT DIRECTION ON SUBSTRATE 63 
130.degree. 
90.degree. 
90`0 
LC'S TWIST ANGLE 240.degree. 
240.degree. 
240.degree. 
RETARDATION (.DELTA.n .multidot. d) 
600 nm 
600 nm 
600 nm 
SUBSTRATE 63'S POLARIZING DIRECTION 
30.degree. 
30.degree. 
30.degree. 
71 
LC'S ALIGNMENT DIRECTION ON SUBSTRATE 63 
-200.degree. 
-200.degree. 
-200.degree. 
LC'S ALIGNMENT DIRECTION ON SUBSTRATE 3 
40.degree. 
40.degree. 
40.degree. 
LC'S TWIST ANGLES 240.degree. 
240.degree. 
240.degree. 
RETARDATION (.DELTA.n .multidot. d) 
1400 nm 
1400 nm 
1400 nm 
POLARIZING PLATE 72'S POLARIZING DIRECTION 
60.degree. 
60.degree. 
60.degree. 
__________________________________________________________________________ 
FIG. 12(a) is a graph showing a simulation curve of voltages versus 
transmittance of the image element corresponding to the cyan color filter 
6a of the liquid crystal layer 70 for green light and blue light under the 
conditions set forth in TABLE 18. FIG. 12(b) is a graph showing a 
simulation curve of voltages versus transmittance of the image element 
corresponding to the magenta color filter 6b of the liquid crystal layer 
70 for red light and blue light under the conditions set forth in TABLE 
18. FIG. 12(c) is a graph showing a simulation curve of voltages versus 
transmittance of the image element corresponding to the yellow color 
filter 6c of the liquid crystal layer 70 for red light and green light 
under the conditions set forth in TABLE 18. 
Similarly, FIG. 13(a) is a graph showing a simulation curve of voltages 
versus transmittance of the image element corresponding to the cyan color 
filter 6a of the liquid crystal layer 71 for green light and blue light 
under the conditions set forth in TABLE 18. FIG. 13(b) is a graph showing 
a simulation curve of voltages versus transmittance of the image element 
corresponding to the magenta color filter 6b of the liquid crystal layer 
71 for red light and blue light under the conditions set forth n TABLE 18. 
FIG. 13(c) is a graph showing a simulation curve of voltages versus 
transmittance of the image element corresponding to the yellow color 
filter 6c of the liquid crystal layer 71 for red light and green light 
under the conditions set forth in TABLE 18. 
The birefringence interference colors set forth in TABLE 17 can be changed 
by selecting voltages indicated by arrows a.cndot.b in the simulation 
curves shown in FIGS. 12(a) through 12(c) and FIGS. 13(a) through 13(c). 
For example, when blue light alone is to be passed through the image 
element corresponding to the cyan color filter 6a, then voltages indicated 
by the arrows a are selected, and when blue light and green light are to 
be passed through the same image element, then voltages indicated by the 
arrows b are selected. 
In the following, a color displayed by a pixel based on transmitted light 
from the liquid crystal layers 70.cndot.71 for each image element is set 
forth in TABLEs 19 through 26 below. 
A pixel is displayed red when the applied voltages are controlled in such a 
manner that the liquid crystals have a combination of retardation for 
transmitting the light of colors as set forth in TABLE 19 below. 
TABLE 19 
______________________________________ 
DISPLAY IN RED 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE ALONE RED ALONE RED ALONE 
LAYER 70 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL GREEN ALONE BLUE & RED GREEN & RED 
LAYER 71 
COLOR OF BLACK RED RED 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in green when the applied voltages are controlled in 
such a manner that the liquid crystals have a combination of retardation 
for transmitting the light of colors as set forth in TABLE 20 below. 
TABLE 20 
______________________________________ 
DISPLAY IN GREEN 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE & GREEN 
RED ALONE RED & GREEN 
LAYER 70 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL GREEN ALONE BLUE ALONE GREEN ALONE 
LAYER 71 
COLOR OF GREEN BLACK GREEN 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in blue when the applied voltages are controlled in 
such a manner that the liquid crystals have a combination of retardation 
for transmitting the light of colors as set forth in TABLE 21 below. 
TABLE 21 
______________________________________ 
DISPLAY IN BLUE 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE ALONE BLUE & RED RED ALONE 
LAYER 70 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE & GREEN 
BLUE ALONE GREEN ALONE 
LAYER 71 
COLOR OF BLUE BLUE BLACK 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in cyan when the applied voltages are controlled in 
such a manner that the liquid crystals have a combination of retardation 
for transmitting the light of colors as set forth in TABLE 22 below. 
TABLE 22 
______________________________________ 
DISPLAY IN CYAN 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE & GREEN 
BLUE & RED RED & GREEN 
LAYER 70 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE & GREEN 
BLUE ALONE GREEN ALONE 
LAYER 71 
COLOR OF CYAN BLUE GREEN 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in magenta when the applied voltages are controlled 
in such a manner that the liquid crystals have a combination of 
retardation for transmitting the light of colors as set forth in TABLE 23 
below. 
TABLE 23 
______________________________________ 
DISPLAY IN MAGENTA 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE ALONE RED & BLUE RED ALONE 
LAYER 70 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE & GREEN 
RED & BLUE GREEN & RED 
LAYER 71 
COLOR OF BLUE MAGENTA RED 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in yellow when the applied voltages are controlled 
in such a manner that the liquid crystals have a combination of 
retardation for transmitting the light of colors as set forth in TABLE 24 
below. 
TABLE 24 
______________________________________ 
DISPLAY IN YELLOW 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE & GREEN 
RED ALONE RED & GREEN 
LAYER 70 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL GREEN ALONE RED & BLUE RED & GREEN 
LAYER 71 
COLOR OF GREEN RED YELLOW 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in black when the applied voltages are controlled in 
such a manner that the liquid crystals have a combination of retardation 
for transmitting the light of colors as set forth in TABLE 25 below. 
TABLE 25 
______________________________________ 
DISPLAY IN BLACK 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE ALONE RED ALONE RED ALONE 
LAYER 70 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL GREEN ALONE BLUE ALONE GREEN ALONE 
LAYER 71 
COLOR OF BLACK BLACK BLACK 
TRANSMITTED 
LIGHT 
______________________________________ 
The pixel is displayed in white when the applied voltages are controlled in 
such a manner that the liquid crystals have a combination of retardation 
for transmitting the light of colors as set forth in TABLE 26 below. 
TABLE 26 
______________________________________ 
DISPLAY IN WHITE 
FILTER 6a FILTER 6b FILTER 6c 
(CYAN) (MAGENTA) (YELLOW) 
______________________________________ 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE & GREEN 
RED & BLUE RED & GREEN 
LAYER 70 
LIQUID TRANSMITS TRANSMITS TRANSMITS 
CRYSTAL BLUE & GREEN 
RED & BLUE RED & GREEN 
LAYER 71 
COLOR OF CYAN MAGENTA YELLOW 
TRANSMITTED 
LIGHT 
______________________________________ 
As shown in TABLEs 19 through 24, two primary colors out of three pass 
through each color filter, and two image elements out of three are 
displayed in the same colors. Thus, like the first and fourth embodiments, 
a full-color liquid crystal display device of the present embodiment can 
double not only the utilization efficiency of incident light, but also the 
brightness compared with a case where the conventional red, blue, and 
green filters are used. 
The transmission type liquid crystal display device of the present 
embodiment using the CMY filter and a conventional liquid crystal display 
device using the RGB filter are compared in terms of the dependency of the 
utilization efficiency on the incident light's wavelength when the pixel 
is displayed in white, and the result of which is shown in FIG. 5. As 
shown in FIG. 5, the utilization efficiency (brightness) in the liquid 
crystal display device of the present embodiment in increased two-fold 
compared with the conventional liquid crystal display device when the 
pixel is displayed in white as was in the first and fourth embodiments. 
In addition, the brightness is increased two-fold without impairing the 
purity of each color when the pixels are displayed in red, green, blue, 
cyan, magenta, yellow, and white individually. 
Also, since the liquid crystal layers 70.cndot.71 are made of twisted 
liquid crystals twisted 240.degree., they can be driven by the 
multiplex-multiplex drive. When the twist angle is less than 180.degree., 
the steepness of a curve representing the applied voltage-transmittance 
characteristics is degraded. Thus, it is preferable to set the twist angle 
in a range between 180.degree. and 360.degree. inclusive, because the 
applied voltage-transmittance characteristics curve shows excellent 
steepness if the twist angle is within the above-specified range. 
SIXTH EMBODIMENT! 
Referring to FIG. 14, the following description will discuss still another 
embodiment of the present invention. Like components are labelled with 
like numerals with respect to the first, second, and fourth embodiments 
and the explanation of these components is not repeated for the 
explanation's convenience. 
A liquid crystal display device of the present embodiment is of a 
reflective type. As shown in FIG. 14, the liquid crystal display device of 
the present embodiment is different from the counterpart of the fifth 
embodiment in that the dielectric mirror layer 21 of the second embodiment 
which reflects cyan light, magenta light, and yellow light is provided on 
a lower surface of the transparent electrode 10 instead of the color 
filter layer 6 of the fifth embodiment which transmits cyan light, magenta 
light, and yellow light, and the photo-absorbing layer 26 which absorbs 
incident light is provided between the dielectric mirror layer 21 and 
transparent substrate 3. The dielectric mirror layer 21, which is provided 
for each of three image elements forming a pixel, comprises the dielectric 
mirrors 21a, 21b, and 21c which reflect cyan light, magenta light, and 
yellow light, respectively. 
In the above-structured liquid crystal display device, each of the liquid 
crystal layers 70.cndot.71 show interference colors due to the 
birefringence interference and optical rotatory dispersion, and the 
interference colors can be changed by changing the retardation and optical 
rotatory characteristics using applied voltages from pairs of the 
transparent electrodes 7.cndot.8 and 9.cndot.10. 
More specifically, a bright display in colors including white, black, red, 
green, blue, cyan, magenta, and yellow can be realized when the liquid 
crystal layers 70 and 71 which render the color display characteristics as 
set forth in TABLE 17 are combined with the cyan color filter 6a, magenta 
color filter 6b, and yellow color filter 6c. 
Compared with the reflective type liquid crystal display device of the 
fifth embodiment which includes the reflecting plate, the structure can be 
simplified as the dielectric mirror layer 21 per se serves as the 
reflecting plate as well as a color selector. 
Each image element and pixel are displayed in specific colors corresponding 
to the states of the liquid crystal layers 70.cndot.71 in the same manner 
as the fifth embodiment, and the explanation thereof is omitted herein. 
The invention being thus described, it will be obvious that the same may be 
varied in many ways. Such variations are not to be regarded as a departure 
from the spirit and scope of the invention, and all such modification as 
would be obvious to one skilled in the art are intended to be included 
within the scope of the following claims.