HK1033364A - Reflective liquid crystal display - Google Patents

Description

Reflective color liquid crystal display device

Technical Field

The present invention relates to a reflective liquid crystal display device, and more particularly, to a reflective color liquid crystal display device having a color filter built therein and capable of displaying a plurality of colors.

Technical Field

As a conventional reflective liquid crystal display device, a reflective liquid crystal display device which performs black-and-white (monochrome) display using a TN (twisted nematic) liquid crystal element (cell) or an STN (super twisted nematic) liquid crystal element (cell) has been mainly used. However, in recent years, the demand for colorization has been strong, and the development of a reflective liquid crystal display device incorporating a color filter has been vigorously carried out.

The reflective liquid crystal display device having a color filter incorporated therein is roughly classified into the following 3 types.

The 1 st conventional example uses a liquid crystal mode without using a polarizing plate at all. A guest-host system in which a black dye is mixed into a liquid crystal material, a polymer dispersion system in which a liquid crystal material is dispersed in a polymer, and the like. In either of these methods, a polarizing plate is not used, and therefore, although the luminance is good, the contrast is low, and the practical use has not yet been achieved.

A conventional example using the guest-host system is disclosed in, for example, japanese patent laid-open No. 59-198489. A conventional example using a polymer dispersion method is disclosed in, for example, Japanese patent application laid-open No. 5-241143.

The conventional example 2 uses 1 polarizing plate, and the reflecting plate is disposed inside the liquid crystal display device. This mode can be further subdivided into 2 types, that is, a type using a built-in reflection sheet of a mirror surface and provided with a diffusion layer on the surface thereof, and a type using a reflection sheet having a scattering property. In either type, since only 1 polarizing plate is used, the contrast is low although the brightness is good.

In the case of the type of the built-in reflection sheet using a mirror surface, the regular reflection direction of incident light is bright, but it is sharply darkened at angles other than the normal reflection direction, and the viewing angle characteristic is very poor. In the case of the other type using a reflective sheet having scattering properties, the scattering properties are difficult to control, and the manufacturing process is complicated. A conventional example of a reflection type liquid crystal display device using this single polarizing plate is disclosed in, for example, japanese unexamined patent application publication No. h 3-223715.

The 3 rd conventional example is a liquid crystal display device using 2 polarizing plates and including a color filter in a normal black-and-white liquid crystal display device. Since 2 polarizing plates were used, the contrast was good, but the display was dark. However, the use of a reflective polarizing plate as the lower polarizing plate can improve the luminance, and practical use thereof is under study. A conventional example using such a reflective polarizing plate is disclosed in, for example, Japanese patent application laid-open No. Hei 10-3078.

In addition, in a conventional transmissive color liquid crystal display device using backlight illumination, a color filter having a thickness of 0.5 to 1.5 μm, which is formed by adding 25 to 40% of a color resist to a photosensitive resin, is used. In the spectral spectrum of the color filter, when the maximum transmittance is defined as the maximum transmittance and the minimum transmittance is defined as the minimum transmittance for one color, the maximum transmittance is about 80% to 90%, and the minimum transmittance is 10% or less.

On the other hand, in the reflective liquid crystal display device according to the above-described conventional example 3, in order to improve the luminance, it is necessary to set the maximum transmittance of the color filter to 90% or more and the minimum transmittance to 20% or more, and therefore, the thickness of the color filter is set to 0.2 μm or less.

However, when the thickness of the color filter is reduced, the adhesion between the color filter and a glass substrate constituting the liquid crystal cell is reduced, and as a result, there is a problem that the color filter is peeled off or the width becomes narrower than a desired width in an etching step.

Further, in the conventional reflective liquid crystal display device using the STN liquid crystal element, since birefringence cannot be completely corrected, a white color tone is yellowish, and color balance is not good.

Disclosure of the invention

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a reflective color liquid crystal display device which can perform bright and high-chroma display without peeling off a color filter.

The 2 nd object is to provide a reflective color liquid crystal display device which has a good white color tone and a good color balance even in a reflective color liquid crystal display device using an STN liquid crystal element.

In order to achieve the above object, a reflective color liquid crystal display device according to the present invention includes the following configuration.

The STN liquid crystal cell comprises a transparent 1 st substrate having a 1 st electrode, a transparent 2 nd substrate having a 2 nd electrode, a color filter comprising a multicolor color filter provided on one of the 1 st and 2 nd substrates, and a nematic liquid crystal enclosed between the 1 st and 2 nd substrates and having a twisted orientation of 180 to 270 degrees.

A polarizing plate is provided on the outer side of the 2 nd substrate which is the viewing side of the STN liquid crystal cell, and 1 or more phase difference plates are provided between the polarizing plate and the 2 nd substrate. Further, a diffusion layer, a reflective polarizing plate, and a light absorbing layer are provided in this order on the outer side of the 1 st substrate of the STN liquid crystal cell.

The color filter is formed by using a color resist in which 5 to 20% of a pigment is blended into a photosensitive resin so that the maximum transmittance is 80% or more and the minimum transmittance is 20 to 50% and the thickness is 0.5 to 2.0 μm.

As described above, by using a color filter in which a pigment is dispersed and the pigment concentration is lower than that of a conventional color filter (the pigment is blended to 25% to 40%), it is possible to perform bright display without making the thickness of the color filter thin.

Further, since the thickness of the color filter is substantially the same as that of the color filter of the conventional transmissive color liquid crystal display device, the adhesion force with the glass substrate of the STN liquid crystal cell becomes strong, and bright and high-chroma color display can be performed without causing peeling defects of the color filter and without narrowing the width of the color filter at the time of etching.

When the refractive index of the retardation plate in the stretching direction is defined as nx, the refractive index of the retardation plate in the direction perpendicular to the stretching direction is defined as ny, and the refractive index of the retardation plate in the thickness direction is defined as nz, the viewing angle can be improved by using a so-called Z-type retardation plate satisfying the condition that nx > nz > ny, and incident light from the periphery can be effectively utilized, thereby obtaining a brighter display.

A twisted phase difference plate may be provided between the polarizing plate and the 2 nd substrate instead of the phase difference plate.

As the color filter, a color filter composed of a red color filter, a green color filter, and a blue color filter, or a color filter composed of a cyan color filter, a magenta color filter, and a yellow color filter may be used, but a color filter composed of a 2-color or 4-color or more color filter may also be used.

When a color filter including a red color filter, a green color filter, and a blue color filter is used, the maximum transmittance of each color filter is set in the following order:

blue filter > green filter > red filter the filters become blue if used alone, but the color balance resulting from the combination is improved due to the yellowing characteristic of STN liquid crystal, and good white display can be obtained.

Further, since the light shielding layer formed of the blue color filter is provided in the gap between the color filters of the respective colors among the color filters formed of the red color filter, the green color filter and the blue color filter, blue light is incident on the pixel for displaying white color formed of the STN liquid crystal from between the pixels, and white display with good color balance can be obtained.

In the reflective color liquid crystal display device, a semi-transmissive light absorption layer is provided instead of the light absorption layer, and a backlight is provided on the side of the semi-transmissive light absorption layer opposite to the reflective polarizing plate, so that bright display can be performed even in a dark environment such as at night by light emission from the backlight.

Further, 1 or more retardation plates and diffusion layers may be provided between the 2 nd substrate serving as the STN liquid crystal element and a polarizing plate provided outside the retardation plates, and a liquid crystal element having a reflective layer for reflecting light transmitted through a color filter provided outside the 1 st substrate may be used as the STN liquid crystal element, and nothing may be provided outside the 1 st substrate.

In this case, the color filter composed of the multicolor color filter provided in the STN liquid crystal cell is also the same as the above-described color filter.

Brief description of the drawings

Fig. 1 is a schematic sectional view showing the configuration of example 1 of the reflective color liquid crystal display device of the present invention.

Fig. 2 is a plan view showing an example of the shape of the color filter and the 2 nd electrode in example 1.

Fig. 3 is an explanatory view showing the arrangement relationship between the STN liquid crystal cell and the reflective polarizing plate of example 1.

Fig. 4 is an explanatory view showing the arrangement relationship between the absorption polarizing plate and the phase difference plate of example 1.

Fig. 5 is a graph showing spectral characteristics of a color filter in the reflective color liquid crystal display device shown in fig. 1.

Fig. 6 is a graph showing spectral characteristics in an ON state and an OFF state when the color filter is removed from the reflective color liquid crystal display device shown in fig. 1.

Fig. 7 is a schematic sectional view showing the configuration of example 2 of the reflective color liquid crystal display device of the present invention.

Fig. 8 is a plan view showing an example of the shape of the color filter and the 2 nd electrode of example 2.

Fig. 9 is an explanatory view showing the arrangement relationship between the STN liquid crystal cell and the reflective polarizing plate of example 2.

Fig. 10 is an explanatory view showing the arrangement relationship between the absorption polarizing plate and the twisted phase difference plate of example 2.

Fig. 11 is a schematic sectional view showing the configuration of example 3 of the reflective color liquid crystal display device of the present invention.

Fig. 12 is a plan view showing an example of the shape of the color filter and the 1 st and 2 nd electrodes in example 3.

Fig. 13 is a schematic sectional view showing the configuration of example 4 of the reflective color liquid crystal display device of the present invention.

Fig. 14 is a plan view showing an example of the shape of the color filter and the 2 nd electrode and the reflective layer of example 4.

PREFERRED EMBODIMENTS

In order to explain the present invention in more detail, preferred embodiments of the present invention are explained with reference to the accompanying drawings.

Example 1: FIGS. 1 to 6

First, embodiment 1 of a reflective color liquid crystal display device according to the present invention will be described with reference to fig. 1 to 6.

Fig. 1 is a schematic cross-sectional view showing the configuration of example 1 of the reflective color liquid crystal display device of the present invention, and fig. 2 shows an example of the shapes of the color filter and the 2 nd electrode. Fig. 3 and 4 are plan views showing the arrangement relationship of the respective components, fig. 5 is a graph showing the spectral characteristics of the color filter, and fig. 6 is a graph showing the spectral characteristics in the ON state and the OFF state when the color filter is removed from the reflective color liquid crystal display device shown in fig. 1. As shown in fig. 1, the reflective color liquid crystal display device of example 1 is configured such that: a1 st transparent substrate 1 and a 2 nd transparent substrate 2 each composed of a glass substrate 0.5mm thick are bonded together with a sealant 5 with a predetermined distance therebetween, and a nematic liquid crystal 6 twisted at 225 DEG is enclosed and sandwiched between the 1 st substrate 1 and the 2 nd substrate 2, thereby constituting an STN liquid crystal element 20.

On the inner surface of the 1 st substrate 1, a transparent 1 st electrode 3 made of indium tin oxide (hereinafter, abbreviated as "ITO") is formed in a stripe shape at intervals in a direction perpendicular to the paper surface.

Further, a color filter 7 having a thickness of 1.0 μm formed by a pigment dispersion method and a protective film 8 having a thickness of 2 μm made of an acrylic material were formed on the inner surface of the 2 nd substrate 2, and the 2 nd electrode 4 made of ITO was formed on the protective film 8.

An absorbing polarizing plate 11 having a transmission axis and an absorption axis (hereinafter simply referred to as a polarizing plate) as a general polarizing plate is provided on the outer side (upper side in fig. 1) of the 2 nd substrate 2 on the viewing side of the STN liquid crystal cell 20, and a phase difference plate 12 is disposed between the polarizing plate 11 and the 2 nd substrate 2. The polarizing plate 11 may have a transmittance of about 46%, and the phase difference Rf of the phase difference plate 12 may be Rf of about 0.55 μm.

Further, a diffusion layer 13, a reflective polarizing plate 14, and a light absorbing layer 15 are sequentially disposed on the outer side (lower side in fig. 1) of the 1 st substrate which is opposite to the viewing side of the STN liquid crystal element 20.

Thus, a reflective color liquid crystal display device is constituted by the STN liquid crystal element 20 with a built-in color filter, the polarizing plate 11 and the retardation plate 12 disposed on the viewing side thereof, and the diffusion layer 13, the reflective polarizing plate 14 and the light absorbing layer 15 disposed on the side opposite to the viewing side.

Here, the reflective polarizing plate 14 will be explained. While a typical polarizing plate is an absorption polarizing plate having a transmission axis through which light is transmitted and an absorption axis through which light is absorbed, the reflective polarizing plate 14 has a transmission axis and a reflection axis (perpendicular to the transmission axis) through which light is reflected. If black printing or a black film is disposed as the absorbing layer 15 on the outer side of the reflective polarizing plate 14, black display is performed when the polarization direction of incident linearly polarized light is the transmission axis direction, and white display is performed when the polarization direction is the reflection axis direction.

The surface of the reflective polarizing plate 14 is a mirror surface, and the regular reflection direction of incident light is bright, but it becomes dark at any angle other than the normal reflection direction, and the viewing angle characteristic is not good. In order to improve the viewing angle characteristics, a diffusion layer 13 is provided on the surface of the reflective polarizing plate 14.

In this example, a product manufactured by sumitomo 3M company under the trade name R-DF-B, which is an integrated reflective polarizing plate, was used, and a diffusion adhesive layer in which fine particles were dispersed in an adhesive was formed as a diffusion layer 13 on the front surface, and black printing was performed as a light absorbing layer 15 on the back surface. The reflective polarizing plate is formed of a multilayer film having different refractive indices, but in addition to this, for example, a reflective polarizing plate formed by sandwiching a cholesteric liquid crystal polymer with a λ/4 plate or a reflective polarizing plate using holography may be used.

The retardation plate 12 is a film of about 70 μm in thickness obtained by stretching a polycarbonate, and when the refractive index in the stretching direction is defined as nx, the refractive index in the direction perpendicular to the stretching direction is defined as ny, and the refractive index in the thickness direction is defined as nz > ny. This is a so-called Z-type retardation plate, and is integrated with the polarizing plate 11 with a polyacrylic adhesive. The Z-type retardation plate has a small change in optical path length difference when the viewing angle is tilted, and as a result, the viewing angle characteristics of the liquid crystal display device are improved.

The color filter 7 is formed of 3 colors of red filter R, green filter G, and blue filter B, and has a vertical stripe shape with a constant width as shown in fig. 2. The color filters of the respective colors are wider than the 2 nd electrode 4 so as not to generate a gap. If a gap is formed between the color filters of the respective colors of the color filter 7, the color becomes brighter due to an increase in incident light, but the color purity is undesirably reduced due to white light mixed into the display color.

Next, the relationship between the thickness and the color of the 1 st substrate 1 will be described. The color filter 7 is disposed inside the 2 nd substrate 2, and incident light passes through the polarizing plate 11, the retardation plate 12, the 2 nd substrate 2, the color filter 7, and the nematic liquid crystal 6, passes through the 1 st substrate 1, is reflected by the reflective polarizing plate 14, passes through the 1 st substrate 1, the nematic liquid crystal 6, and the color filter 7 again, and finally passes through the polarizing plate 11 to reach the eyes of the observer.

However, if the thickness of the 1 st substrate 1 is large, the color of the color filter 7 transmitted when incident light is transmitted is different from the color of the color filter 7 transmitted when reflected, and chromaticity is lowered by color mixing. Therefore, the thinner the 1 st substrate 1 is, the less color mixture is caused by the incident light from the oblique direction, and the more favorable color can be obtained.

It was found that, when the STN liquid crystal element 20 in which the thickness of the 1 st substrate 1 was variously changed was manufactured, a good color was obtained when the thickness was 0.5mm or less. The thinner the 1 st substrate 1, the better the color, but if it is too thin, the workability is lowered and the strength is weakened, so it is preferable to have a thickness of 0.1mm or more. In this example, as the 1 st substrate 1 and the 2 nd substrate 2, glass plates of 0.5mm were used.

The color filter 7 preferably has a maximum transmittance as high as possible to improve the luminance, and the maximum transmittance of each color filter is preferably 80% or more, more preferably 90% or more. In addition, the minimum transmittance in the spectroscopic spectrum must also be as high as 20% to 50%.

As the color filter, a pigment dispersion type, a dyeing type, a printing type, a transfer type, an electrodeposition type, and the like can be used, but a pigment dispersion type color filter in which a pigment is dispersed in an acrylic PVA-based photosensitive resin is most preferable because it has a high heat resistance temperature and a good color purity.

In order to obtain such a pigment dispersion type color filter having a high transmittance, conventionally, a color resist containing 25 to 40% of a pigment blended into a photosensitive resin is applied onto the 2 nd substrate 2 by a rotary coater, and then an exposure step and a development step are performed to form a thin color filter having a thickness of 0.3 μm or less. However, when the color filter is thin, the adhesion with the 2 nd substrate is deteriorated, a partial peeling defect of the color filter is generated, over-etching is formed, the width of the color filter is narrowed, or the side edge of the color filter is jagged, and thus a stable shape cannot be obtained.

In this example, by using a color resist in which about 10% of a pigment is blended into a photosensitive resin, the color filter 7 having a maximum transmittance of 90% or more and a minimum transmittance of about 40% in a spectral spectrum can be formed while having a thickness of about 1.0 μm. The color filter 7 has good adhesion and can be obtained in a desired size with a constant width and no gap. The blending ratio of the pigment to the photosensitive resin is not limited to 10%, and the range of 5% to 20% is an optimum ratio in terms of the thickness and the like.

The spectral characteristics of the color filter 7 used in the present embodiment are shown in fig. 5. The curves 31, 32 and 33 show spectral characteristics of the blue color filter B, the green color filter G and the red color filter R, respectively. The maximum transmittance of the color filter of any color is about 90%, and the minimum transmittance is about 25% to 40%. If the minimum transmittance is less than 20%, dark display is obtained, whereas if the minimum transmittance is more than 50%, chromaticity is lowered, which is not preferable.

Although the same spectral characteristics as those of the color filter used in this example were obtained in color filters of various thicknesses by adjusting the concentration of the pigment with respect to the photosensitive resin, the adhesiveness to the 2 nd substrate was deteriorated if the thickness of the color filter was 0.5 μm or less. On the other hand, if the pigment concentration is too low, the thickness of the color filter becomes 2 μm or more, and the thickness unevenness or the step difference of the overlapping portion of the 3-color filter becomes large, which is not satisfactory. Therefore, the thickness of the color filter is preferably about 0.5 to 2.0 μm, and preferably about 1.0 μm or less, which is used in the present example.

The transmittances of the 1 st electrode 3 and the 2 nd electrode 4 made of ITO are also important in terms of luminance. The lower the sheet resistance value of ITO, the thicker the film thickness and the lower the transmittance. Since the data signal is applied to the 1 st electrode 3, the influence of crosstalk is small, and ITO having a sheet resistance value of 10 ohms is used, so that the average transmittance is about 92%.

The 2 nd electrode 4 is supplied with a scanning signal, and ITO having a sheet resistance of about 10 ohms is used for reducing crosstalk, and the average transmittance thereof is about 89%, but as shown in this example, a transparent electrode having a transmittance of 90% or more is used for at least one electrode, and sufficient luminance can be obtained.

Next, the arrangement relationship of the respective constituent members will be described with reference to fig. 3 and 4. Alignment films (not shown) were formed on the surfaces of the 1 st electrode 3 and the 2 nd electrode 4 shown in FIG. 1, and as shown in FIG. 3, the lower liquid crystal molecular alignment direction 6a of the nematic liquid crystal 6 was 22.5 degrees in the counterclockwise direction by rubbing the alignment film on the 1 st substrate 1 side in the direction of 22.5 degrees to the upper right of the horizontal axis H-H. On the other hand, the upper liquid crystal molecular alignment direction 6b of the nematic liquid crystal 6 was 22.5 ° clockwise by rubbing the alignment film on the 2 nd substrate 2 side in the direction 22.5 ° below and to the right of the horizontal axis H-H.

A nematic liquid crystal 7 having a viscosity of 20cp sandwiched between a 1 st substrate 1 and a 2 nd substrate 2 is added with a rotating substance called a chiral agent to adjust a twist pitch P to 11 μm, thereby constituting an STN liquid crystal element 20 twisted at an angle of 225 DEG in the left-handed direction.

The difference Δ n in birefringence of the nematic liquid crystal 6 used was 0.15, and the cell gap d as the gap between the 1 st substrate 1 and the 2 nd substrate 2 was set to 5.6 μm. Therefore, the Δ nd value Rs of the STN liquid crystal cell 20 expressed by the product of the difference Δ n in birefringence of the nematic liquid crystal 6 and the cell gap d is 0.84 μm.

The transmission axis 14a of the reflective polarizing plate 14 is arranged at 70 ° in the counterclockwise direction with reference to the horizontal axis H-H shown in fig. 3, the transmission axis 11a of the polarizing plate 11 is arranged at 70 ° in the clockwise direction with reference to the horizontal axis H-H shown in fig. 3, and the stretching axis 12a of the phase difference plate 12 is arranged at 60 ° in the counterclockwise direction with reference to the horizontal axis H-H shown in fig. 4.

In the reflection type liquid crystal display device of the present embodiment configured as described above, the normally white mode in which white is displayed is set in a state where no voltage (OFF) is applied, and light is also incident from between the pixels (the portions where the 1 st electrode 3 and the 2 nd electrode 4 intersect), whereby bright display can be obtained. When a voltage (ON) is applied between the 1 st electrode 3 and the 2 nd electrode 4, molecules of the nematic liquid crystal 6 stand to display black. By combining ON and OFF for each color, full color display is possible.

Fig. 6 shows the ON and OFF spectral characteristics in the case where the color filter 7 is removed from the reflective liquid crystal display device shown in fig. 1. The solid curve 35 shows the spectral characteristics of white display when OFF, and the solid curve 36 shows the spectral characteristics of black display when ON is driven at a frame frequency of 120 Hz.

In the reflective color liquid crystal display device, in order to improve the luminance, the average transmittance is designed to be the highest at the OFF time as shown by the curve 35 although the yellow color is somewhat strong, and the light is almost equally blocked in all the wavelength regions at the ON time as shown by the curve 36, so that a good black characteristic can be obtained.

In this example, in order to improve the whiteness at the time of OFF, as shown in fig. 5, the highest transmittance of the color filters of the respective colors constituting the color filter 7 is set in the following order

The blue filter > green filter > red filter exhibits blue emission when the filter 7 is used alone, but the color balance can be improved by combining the blue emission with the yellowing characteristic of the STN liquid crystal cell 20.

Further, by using a Z-type retardation plate in which nx > nz > ny as the retardation plate 12, the viewing angle characteristics can be improved. Since the viewing angle characteristics are improved, light from various directions is incident, and as a result, the display becomes bright, and a reflective color liquid crystal display device having better characteristics can be obtained.

When the response speed of the STN liquid crystal element 20 is high, the contrast can be improved by increasing the frame rate as the driving frequency. However, since crosstalk occurs when the frame frequency is too high, the frame frequency is preferably 100 to 200 Hz. In this embodiment, a 60Hz video signal is temporarily written into a memory and then read out at a rate 2 times faster, and driven at a frame rate of 120 Hz.

In this example, as described above, in the reflective color liquid crystal display device constituted by the polarizing plate 11, the Z-type retardation plate 12, the STN liquid crystal cell 20, and the reflective polarizing plate 14, by providing the STN liquid crystal cell 20 with a color filter having a thickness of about 1.0 μm, a maximum transmittance of 80% or more, and a minimum transmittance of 20% to 50%, a bright reflective color liquid crystal display device having no peeling defect of the color filter can be obtained.

Example 1 modification

In example 1 described above, the STN liquid crystal cell 20 having a 225 ° twist and Rs of 0.84 μm was used as the STN liquid crystal cell, but even when the STN liquid crystal cell having a 180 to 270 ° twist and Rs of 0.7 to 1.0 was used, a similar reflective color liquid crystal display device could be obtained by optimizing the arrangement angles of the polarizing plate 11, the phase difference plate 12, and the reflective polarizing plate 14.

In example 1, although the color filter 7 used was a color filter composed of 3 colors of red, green and blue, even when a color filter composed of cyan, yellow and magenta filters was used, by adjusting the pigment concentration in the same manner, a color filter having a thickness of about 1.0 μm, a maximum transmittance of 80% or more and a minimum transmittance of 20% to 50% was obtained, and by disposing this color filter in the STN liquid crystal cell, bright color display was possible.

In example 1, the polarizing plate 11 having a transmittance of 46% was used, but in order to obtain good luminance, it is preferable to use a polarizing plate having a transmittance of 45% or more and a polarization degree of 95% or more. Of course, even a polarizing plate having a transmittance of less than 45% can be used although it is somewhat dark.

In embodiment 1, one phase difference plate 12 is provided, but a plurality of phase difference plates may be provided. Good contrast can still be obtained by using a plurality of phase difference plates and optimizing the arrangement angle and the phase difference value.

In example 1, the retardation plate 12 is provided between the 2 nd substrate 2 and the polarizing plate 11, but the same effect can be obtained even when the retardation plate is provided between the 1 st substrate 1 and the diffusion plate 13.

Example 2: FIG. 7 to FIG. 10

Next, example 2 of the reflective color liquid crystal display device of the present invention will be described with reference to fig. 7 to 10.

Fig. 7 is a schematic sectional view showing the configuration of the reflective color liquid crystal display device, and fig. 8 is a plan view showing an example of the shapes of the STN liquid crystal element and the 2 nd electrode. Fig. 9 and 10 are plan views showing the arrangement of the respective components. In these figures, the same reference numerals are given to parts corresponding to fig. 1 to 2.

The reflective color liquid crystal display device of example 2 is different from the reflective color liquid crystal display device of example 1 in that a twist phase difference plate 23 is provided between the polarizing plate 11 and the 2 nd substrate 2 instead of the phase difference plate 12 in example 1 shown in fig. 1, and in that the twist angle of the STN liquid crystal element 21 is different from that of the STN liquid crystal element 20 in example 1, and in that a semi-transmissive light-absorbing plate 25 and a backlight 26 are provided instead of the light-absorbing layer 15 in example 1 and in that a light-shielding layer 9 formed of a blue color filter B is provided on the color filter 17.

That is, as shown in fig. 7, the reflective color liquid crystal display device of example 2 has an STN liquid crystal element 21 composed of the following components. These parts are: a 1 st substrate 1 made of a glass plate having a thickness of 0.5mm and provided with a 1 st electrode 3 made of ITO; a 2 nd substrate 2 composed of a protective film 8 having a thickness of 2 μm and made of a color filter 17 and an acrylic material, and a glass plate having a thickness of 0.5mm and formed with a 2 nd electrode 4 made of ITO; an adhesive 5 for bonding the 1 st substrate 1 and the 2 nd substrate 2 with a predetermined gap therebetween; the nematic liquid crystal 16 is enclosed and sandwiched between the 1 st substrate 1 and the 2 nd substrate 2, and is twisted and oriented by 240 degrees to the left.

On the outside (lower side in fig. 7) of the 1 st substrate 1 of the STN liquid crystal element 21, a diffusion layer 13, a reflective polarizing plate 14, a semi-transmissive light absorption layer 25, and a backlight 26 composed of a white Electroluminescent (EL) panel are disposed in this order. On the other hand, a twisted phase difference plate 23 and a polarizing plate 11 having a transmittance of 46% coated with a non-reflective layer 24 are disposed in this order on the outer side (viewing side) of the 2 nd substrate 2, thereby constituting a reflective color liquid crystal display device.

As the reflective polarizing plate 14, a product name R-DF-C manufactured by sumitomo 3M, in which a black printing with the back surface omitted and a diffusion adhesive layer formed as the diffusion layer 13 on the surface was used. As the semi-transmissive light absorption layer 25, a polyethylene terephthalate (PET) film dyed with a black dye was bonded to the back surface of the reflective polarizing plate 14 so that the transmittance became 40%.

The twist retardation plate 23 is a film in which a liquid crystalline polymer having twist is applied to a triacetyl cellulose (TAC) film or a PET film after alignment treatment, and is brought into a liquid crystal state at a high temperature of about 150 ℃, and after the twist angle is adjusted, the film is rapidly cooled to room temperature to fix the twist state. In the present embodiment, a right-handed twist phase difference plate 23 is used in which the twist angle Tc is 220 ° in the clockwise direction, and Rc as Δ nd is 0.61 μm.

By providing a non-reflective layer 24 having a reflectance of about 0.5% formed by depositing a plurality of inorganic thin films on the surface of the polarizing plate 11, the surface reflection of the polarizing plate 11 is reduced, the transmittance can be improved, and the display can be bright. Further, since the surface reflection light of the polarizing plate 11 is reduced, the black level at the time of ON can be lowered, and the contrast can be improved, a bright and high-chroma reflective color liquid crystal display device can be obtained.

However, since the vapor deposition film is expensive, a coating type non-reflective film coated with 1 to 2 layers of organic material has been recently developed, and the reflectance is about 1% or so, which is somewhat high, but the non-reflective film can be used as the non-reflective layer 24 even if the non-reflective film is inexpensive.

The color filter 17 is formed of 3 colors of a red color filter R, a green color filter G, and a blue color filter B, and in the present embodiment, is in the form of a vertical stripe as shown in fig. 8. A light shielding layer 9 formed of a blue color filter B is formed in a gap portion between the 2 nd electrode 4.

By widening the width of the blue color filter B, the light shielding layer 9 is formed as a gap between the green color filter B and the red color filter R or a gap between the blue color filter B and the green color filter G, and the light shielding layer 9 is formed as a fine light shielding layer by the blue color filter B between the red color filter R and the green color filter G.

By providing the light shielding layer 9 with the blue color filter B, even if the positions of the red color filter R and the green color filter G are deviated, the color purity can be improved because no gap is left. Further, the blue light transmitted through the light-shielding layer 9 can improve the color balance and provide a good white display.

In the color filter 17 of this example, similarly to the color filter 7 used in example 1, a color resist in which a pigment is blended in a photosensitive resin in an amount of 5% to 20% (preferably about 10%) is used to form the color filter 17 having a thickness of 1.0 μm, a maximum transmittance of 90% or more, and a minimum transmittance of 25% to 40% as in the spectral spectrum of the color filter of example 1 shown in fig. 5. The color filter 17 has good adhesion, a constant width and a desired size without a gap. Further, the light shielding layer 9 having a width of 10 μm formed by the blue color filter B between the red color filter R and the green color filter G can also be formed in a preferable shape.

Next, the arrangement relationship of the respective constituent elements of the reflective color liquid crystal display device will be described with reference to fig. 9 and 10.

Alignment films (not shown) are formed on the surfaces of the 1 st electrode 3 and the 2 nd electrode 4 shown in fig. 7, and as shown in fig. 9, the lower liquid crystal molecular alignment direction 16a of the nematic liquid crystal 16 is set to 30 ° in the counterclockwise direction by rubbing the alignment film on the 1 st substrate 1 side in the upper right 30 ° direction with respect to the horizontal axis H-H, and the upper liquid crystal molecular alignment direction 16b of the nematic liquid crystal 16 is set to 30 ° in the clockwise direction by rubbing the alignment film on the 2 nd substrate 2 side in the lower right 30 ° direction with respect to the horizontal axis H-H.

A nematic liquid crystal 16 having a viscosity of 20cp is doped with a gyrable substance called a chiral agent, and the twist pitch P is adjusted to 11 μm to form an STN liquid crystal element 21 having a left-handed twist angle Ts of 240 °.

The difference Δ n in birefringence of the nematic liquid crystal 16 used was 0.15, and the cell gap d as a gap between the 1 st substrate 1 and the 2 nd substrate 2 was set to 5.6 μm. Therefore, Rs, which is a value of Δ nd of the STN liquid crystal element 21 expressed by a product of a difference Δ n in birefringence of the nematic liquid crystal 16 and the cell gap d, is 0.84 μm.

Similarly, the transmission axis 14a of the reflective polarizing plate 14 is arranged 5 ° in the clockwise direction with reference to the horizontal axis H-H shown in fig. 10, the transmission axis 11a of the polarizing plate 11 is arranged 45 ° in the counterclockwise direction with reference to the horizontal axis H-H shown in fig. 10, the lower molecular alignment direction 23a of the retardation plate 23 is twisted, and is arranged 55 ° in the counterclockwise direction with reference to the horizontal axis H-H shown in fig. 10, the upper molecular alignment direction 23b is arranged 85 ° in the clockwise direction, and the twist angle Tc of the right-hand turn is 220 °, and when the absolute value of the twist angle with the STN liquid crystal element 21 is Δ T, Δ T becomes Δ T Ts-Tc of 20 °.

The STN liquid crystal element 21 is preferably corrected when the absolute value of the twist phase difference plate 23 is equal to the absolute value of the twist angle, that is, when Δ T is 0, and a good white color can be obtained at the time of OFF, but a good black color cannot be formed at the time of ON, and the contrast is lowered, and therefore, it is not suitable for use in a reflective color liquid crystal display device. In order to form black having good light valve performance, Δ T is preferably 10 to 30 °, and particularly when Δ T used in the reflective color liquid crystal display device of the present embodiment is 20 °, white transmittance at OFF is high, black has good light valve performance at ON, and viewing angle characteristics are also good.

In the reflective color liquid crystal display device configured as described above, a normally white mode in which white is displayed is set in a state where no voltage (OFF) is applied, and light is incident from between pixels, whereby bright display can be obtained. When a voltage (ON) is applied between the 1 st electrode 3 and the 2 nd electrode 4, molecules of the nematic liquid crystal 16 stand to display black. Full color display is possible by combining ON and OFF for each color.

In addition, in the reflective color liquid crystal display device of the present embodiment, since the transflective light absorption layer 25 and the backlight 26 are provided, it can be seen even at night. However, the light of the backlight 26 is converted into a polarized light component in the transmission axis direction of the transmission reflection type polarizing plate 14, and the polarized light component in the reflection axis direction is not transmitted, so that the display is inverted display in which black and white are inverted. Therefore, by inverting the data signal supplied to the liquid crystal display device when the backlight 26 emits light, normal color display can be obtained.

In this example, a reflective color liquid crystal display device including the polarizing plate 11 having no reflective layer 24, the twisted phase difference plate 23, the STN liquid crystal element 21, and the reflective polarizing plate 14, which is provided with a color filter having a thickness of about 1.0 μm, a maximum transmittance of 80% or more, and a minimum transmittance of 20% to 50%, is provided, and thus a bright reflective color liquid crystal display device having no color filter peeling defect and high color can be provided.

In this embodiment, by providing the light shielding layer 9 formed of the blue color filter B in the gap between the color filters of the respective colors of the color filter 17, the color balance and chromaticity are further improved, and by providing the semi-transmissive light absorbing layer 25 and the backlight 26, it is possible to provide a reflective color liquid crystal display device which can be viewed even at night.

Example 2 modification

In the above-described embodiment 2, the STN liquid crystal element 21 having the twist angle Ts of 240 ° and Rs of 0.84 μm was used as the STN liquid crystal element, but even when the STN liquid crystal element having the twist of 180 to 270 ° and Rs of 0.7 to 1.0 was used, a similar reflective color liquid crystal display device can be obtained by optimizing the arrangement angles of the polarizing plate 11, the twist phase difference plate 23, and the reflective polarizing plate 14.

In example 2, the polarizing plate 11 having a transmittance of 46% was used, but in order to obtain good luminance, it is preferable to use a polarizing plate having a transmittance of 45% or more and a polarization degree of 95% or more. Of course, even a polarizing plate having a transmittance of less than 45% can be used although it is somewhat dark.

In example 2, although a twisted liquid crystal polymer film fixed at room temperature was used as the twisted retardation plate 23, if a temperature compensation type twisted retardation plate in which Rc is changed depending on temperature and only a part of liquid crystal molecules is bonded to a chain-like polymer molecule was used, the brightness and contrast at high temperature could be improved, and a better reflective color liquid crystal display device could be obtained.

In example 2, although a white light-emitting EL panel was used as the backlight 26, a more favorable color was obtained by using a backlight in which a fluorescent lamp of 3 wavelengths was mounted on a light guide plate.

Example 3: FIG. 11 and FIG. 12

Next, example 3 of the reflective color liquid crystal display device of the present invention will be described with reference to fig. 11 and 12.

Fig. 11 is a schematic sectional view showing the configuration of the reflective color liquid crystal display device, and fig. 12 is a plan view showing examples of the shapes of the color filter and the 1 st and 2 nd electrodes. The positional relationship of the respective constituent elements is the same as that in embodiment 1 shown in fig. 3 and 4, and therefore, the same reference numerals are given to the portions corresponding to fig. 1 and 2 in these drawings, and the description thereof will be omitted.

The reflective color liquid crystal display device of example 3 is the same as the reflective color liquid crystal display device of example 1 except that the thickness of the 1 st substrate constituting the STN liquid crystal element is formed thinner than the 2 nd substrate 2, the color filter 27 having an intarsia arrangement is provided as a color filter on the 1 st electrode 3 of the 1 st substrate 31, and a normal 1-axis stretching type phase difference plate is used as a phase difference plate.

As shown in fig. 11, the reflective color liquid crystal display device includes an STN liquid crystal element 22 including: a 1 st substrate 31 made of a glass plate having a thickness of 0.4mm and having a color filter 27 having a thickness of 1.0 μm formed on the 1 st electrode 3 made of ITO by a pigment dispersion method; a 2 nd substrate 32 made of a glass plate having a thickness of 0.7mm and on which a 2 nd electrode 4 made of ITO is formed; a sealant 5 for bonding the 1 st substrate 31 and the 2 nd substrate 32 while maintaining a predetermined interval therebetween; the nematic liquid crystal 6 is enclosed and sandwiched between the 1 st substrate 31 and the 2 nd substrate 32, and is twisted and oriented at 225 ° clockwise.

The diffusion layer 13, the reflective polarizing plate 14, and the light absorbing layer 15 are disposed in this order on the outer side (lower side in fig. 11) of the 1 st substrate 31 of the STN liquid crystal element 22. Further, a retardation plate 18 of a 1-axis stretching type having a retardation Rf of 0.55 μm and a polarizing plate 11 having a transmittance of 46% are disposed in this order on the outer side (viewing side) of the 2 nd substrate 32, thereby constituting a reflective color liquid crystal display device.

As for the reflective polarizing plate 14, a diffusion bonding layer in which fine particles are dispersed in an adhesive is formed as the diffusion layer 13 on the front surface, and an integrated reflective polarizing plate having a black printing layer is used as the light absorbing layer 15 on the back surface, similarly to the reflective polarizing plate used in example 1. Further, the polarizing plate 11 is also the same as the polarizing plate used in embodiment 1 of 6.

By setting the thickness of the 1 st substrate 31 to 0.4mm and making it thinner than the 1 st substrate 1 (thickness of 0.5mm) of example 1, color mixture due to incident light from an oblique direction is further reduced, and hence chromaticity better than that of example 1 can be obtained. The thickness of the 2 nd substrate 32 is 0.7mm in consideration of productivity and price, because it has no influence on display performance. Thus, by merely thinning the thickness of the 1 st substrate 31, a good reflective color liquid crystal display device can be provided without lowering productivity.

The color filter 27 is composed of 3 color filters of a red color filter R, a green color filter G, and a blue color filter B, and in this embodiment, as shown in fig. 12, the color filter is arranged in an oblique mosaic manner, and a light shielding layer 9 formed of the blue color filter B is formed in the gap between the color filter units of the respective colors, as in embodiment 2. Although the color mixing occurs even with the incident light in the vertical direction in fig. 12 by the oblique intarsia arrangement, the chromaticity is reduced, but the chromaticity is not reduced much because the thickness of the 1 st substrate 31 is as thin as 0.4mm in this embodiment.

Further, by providing the light shielding layer 9 with the blue color filter B, even if the positions of formation of the red color filter R and the green color filter G are shifted, a gap is not left, and thus the color purity is improved. Further, the blue light transmitted through the light-shielding layer 9 can improve the color balance, and a good white display can be obtained.

Further, by forming the color filter 27 directly on the 1 st electrode 3, the protective film 8 used in embodiment 1 is not required. Therefore, if the color filter 27 is provided on the 1 st electrode 3, a part of the driving signal applied to the 1 st electrode 3 is lost in the color filter, and the contrast is lowered, but the price can be lowered.

The phase difference plate 18 is a 1-axis stretching type phase difference plate, and has a refractive index nx > ny ═ nz. Therefore, the viewing angle characteristics are lower than those of the Z-type retardation plate 12 used in example 1, but the price can be reduced.

In the present example, in the reflective color liquid crystal display device constituted by the polarizing plate 11, the 1-axis stretching type phase difference plate 18, the STN liquid crystal element 22 and the reflective polarizing plate 14, the color filter 27 having a thickness of about 1.0 μm and an intarsia arrangement having a maximum transmittance of 80% or more and a minimum transmittance of 20% to 50% is directly provided on the 1 st electrode 3, and thus a bright, high-chroma, low-cost reflective color liquid crystal display device free from the peeling defect of the color filter can be provided.

[ modification of example 3 ]

In example 3, the color filter 27 is formed on the 1 st electrode 3 of the 1 st substrate 31, but a similar reflective color liquid crystal display device can be obtained even when the 2 nd electrode 4 of the 2 nd substrate 32 is formed thereon.

In example 3, a glass substrate having a thickness of 0.4mm was used as the 1 st substrate 31, but a favorable color was obtained as the thickness of the 1 st substrate 31 was decreased. However, if it is too thin, workability will be reduced, so the range of 0.1mm to 0.5mm is preferred. In addition, even when a plastic substrate such as polyethylene terephthalate (PET) is used as the 1 st substrate 31, a similar reflective color liquid crystal display device can be obtained.

Example 4: FIG. 13 and FIG. 14

Next, example 4 of the reflective color liquid crystal display device of the present invention will be described with reference to fig. 13 and 14.

Fig. 13 is a schematic sectional view showing the configuration of the reflective color liquid crystal display device, and fig. 14 is a plan view showing an example of the shapes of the color filter, the reflective layer, and the 2 nd electrode. In these figures, the same reference numerals are given to parts corresponding to fig. 1 and 2.

The reflective color liquid crystal display device of example 4 is different from the reflective color liquid crystal display device of example 1 in that the reflective layer 29 is formed on the 1 st substrate 1 of the STN liquid crystal element 28, and the color filter 27 is provided on the reflective layer 29, and the diffusion layer 13 in fig. 1 is moved between the 2 nd substrate 2 of the STN liquid crystal element 28 and the retardation plate 12, and the reflective polarizing plate 14 and the light absorbing layer 15 are not required.

As shown in fig. 13, the reflective color liquid crystal display device includes an STN liquid crystal element 28, a diffusion layer 13 provided on the outer side (viewing side) of the 2 nd substrate 2, a retardation plate 12, and a polarizing plate 11 in this order. The polarizing plate 11 and the retardation plate 12 are integrated with an acrylic adhesive.

The STN liquid crystal cell 28 is formed by bonding a 1 st substrate 1 and a 2 nd substrate 2 each composed of a glass plate having a thickness of 0.5mm with a sealant 5 at a predetermined interval, and sandwiching a nematic liquid crystal 16 twisted at 240 DEG counterclockwise between the 1 st substrate 1 and the 2 nd substrate 2.

On the inner surface of the 1 st substrate 1, a reflective layer 29 made of aluminum and having a thickness of 0.2 μm is formed, and on the reflective layer, a color filter 7 having a thickness of 1 μm and made of 3 color filters of a red color filter R, a green color filter G, and a blue color filter B is formed, and these are covered with a protective film 8 made of an acrylic material and having a thickness of 2 μm. Further, on the upper side of the protective film 8, 1 st electrodes 3 made of ITO are formed in a horizontal stripe shape at intervals in a direction perpendicular to the paper surface in fig. 13.

On the inner surface of the 2 nd substrate 2, as indicated by a virtual line in fig. 14, a 2 nd electrode 4 made of ITO is formed in a vertical stripe shape.

The diffusion layer 13 is provided to scatter the light reflected by the reflection layer 29 and to obtain a bright display with a wide angle of view. A diffusion layer that transmits incident light scattered forward as much as possible and transmits light scattered backward is preferable because a high contrast can be obtained.

Here, as with the diffusion layer used in example 2, a scattering adhesive layer having a thickness of 30 μm was used as the diffusion layer 15, and also used as an adhesive for bonding the liquid crystal element 28 and the retardation plate 12. The polarizing plate 11 and the phase difference plate 12 are the same as those used in example 1.

The color filter 7 is also constituted by 3-color filters of a red color filter R, a green color filter G, and a blue color filter B, similarly to the color filter used in example 1, and is formed in a vertical stripe shape overlapping in parallel with the 2 nd electrode 4 on the reflective layer 29 formed on substantially the entire inner surface of the 1 st substrate 1 of the STN liquid crystal element 28, as shown in fig. 14. The color filters of the respective colors are formed to have a width larger than that of the 2 nd electrode 4 so as not to generate a gap.

If a gap is formed between the color filters R, G, B of the color filter 7, the color becomes brighter due to an increase in incident light, but the color purity is undesirably reduced due to mixing of white light into the display color.

The blending ratio, thickness, maximum transmittance, minimum transmittance, and the like of the pigment to the photosensitive resin of the color filter were the same as those of the color filter of example 1.

In this example, a reflective layer 29 of an aluminum thin film was formed on a 1 st substrate 1, and after the surface of the reflective layer 29 was inactivated by anodic oxidation treatment, a color resist blended in a photosensitive resin by 5% to 20% (about 10% is preferable) was applied on the 1 st substrate 1 by a spin coater, and then an exposure step and a development step were performed to form a color filter 7 having a high transmittance even when the thickness was 1 μm.

The same effects as in example 1 can be obtained with this reflective color liquid crystal display device. Further, since the color filter 7 and the reflective layer 29 are closely attached, a display with good chromaticity can be obtained even with incident light from an oblique direction, and there is no phenomenon that the color of the color filter transmitted at the time of incidence and at the time of reflection is different.

As the color filter of the present embodiment, a color filter composed of cyan, yellow, and magenta color filters may be used, and a color filter composed of 2-color or 4-color or more color filters may be used.

In this example, although the STN liquid crystal element twisted at 240 ° was used as the liquid crystal element 28, a similar reflective color liquid crystal display device can be obtained by adjusting the arrangement angle of the polarizing plate 11 and the retardation plate 12 and the retardation value of the retardation plate 12 even for a liquid crystal element having a twist angle of 200 ° to 260 °.

In the present embodiment, one phase difference plate 12 is used, but a plurality of phase difference plates may be used, and thus a more favorable contrast can be obtained.

In the present embodiment, the color filter 7 is provided on the 1 st substrate 1, but the color filter may be provided inside the 2 nd substrate 2 or between the 2 nd electrode 4 and the 2 nd substrate 2. However, it is preferable to provide the color filter 7 on the 1 st substrate 1 side because the protective film 8 can also serve as an insulating layer between the reflective layer 29 and the 1 st electrode 3 and as a flattening of the color filter 7.

In this example, the surface of the aluminum thin film was inactivated by anodic oxidation treatment as the reflective layer 29 so as to be able to withstand cleaning in a cleaning line in a color filter production process, but SiO may be formed on the aluminum thin film by sputtering or CVD₂And the like. As a material of the reflective layer 29, a thin film of aluminum alloy or silver, or a multilayer film of aluminum and an inorganic oxide may be used.

Possibility of industrial utilization

As described above, according to the reflective color liquid crystal display device of the present invention, bright and high-color display can be performed without causing a color filter peeling defect. Further, white display with good color balance can be performed.

Therefore, the reflective color liquid crystal display device is expected to be widely used in various electronic devices, particularly in portable electronic devices such as watches, mobile phones, Personal Digital Assistants (PDAs), and portable game machines, personal computers, and other various color displays, which are desired to be colored.

Claims (8)

1. A reflective color liquid crystal display device, comprising:

the disclosed device is provided with:

an STN liquid crystal cell comprising a transparent 1 st substrate having a 1 st electrode, a transparent 2 nd substrate having a 2 nd electrode, a color filter comprising a multicolor color filter provided on one of the 1 st and 2 nd substrates, and a nematic liquid crystal sealed between the 1 st and 2 nd electrodes and oriented at 180 to 270 °;

a polarizing plate provided on the outer side of the 2 nd substrate which is a viewing side of the STN liquid crystal cell;

one or more phase difference plates disposed between the polarizing plate and the 2 nd substrate;

a diffusion layer, a reflective polarizing plate and a light absorbing layer are sequentially arranged on the outer side of the 1 st substrate,

the color filter is formed by a color resist obtained by blending 5-20% of a pigment into a photosensitive resin, and has a maximum transmittance of 80% or more and a minimum transmittance of 20-50%, and a thickness of 0.5-2.0 μm.

2. The reflective color liquid crystal display device of claim 1, wherein: the phase difference plate satisfies the condition that nx > nz > ny when the refractive index in the stretching direction is defined as nx, the refractive index in the direction perpendicular to the stretching direction is defined as ny, and the refractive index in the thickness direction is defined as nz.

3. The reflective color liquid crystal display device of claim 1, wherein: a twisted phase difference plate is provided between the polarizing plate and the 2 nd substrate in place of the phase difference plate.

4. The reflective color liquid crystal display device of claim 1, wherein: the color filter is composed of a red color filter, a green color filter and a blue color filter, and the maximum transmittance of the color filters of the colors is as follows: blue filter > green filter > red filter.

5. The reflective color liquid crystal display device of claim 1, wherein: the color filter is composed of a red color filter, a green color filter and a blue color filter, and a light shielding layer formed of a blue color filter is provided between the color filters of the respective colors.

6. The reflective color liquid crystal display device of claim 1, wherein: a semi-transmissive light absorption layer is provided instead of the light absorption layer, and a backlight is provided on the side of the semi-transmissive light absorption layer opposite to the reflective polarizing plate.

7. A reflective color liquid crystal display device, comprising:

the disclosed device is provided with:

an STN liquid crystal cell comprising a transparent 1 st substrate having a 1 st electrode, a transparent 2 nd substrate having a 2 nd electrode, a color filter comprising a multicolor color filter provided on one of the 1 st and 2 nd substrates, and a nematic liquid crystal sealed between the 1 st and 2 nd electrodes and oriented at 180 to 270 °;

a polarizing plate provided on the outer side of the 2 nd substrate which is a viewing side of the STN liquid crystal cell; and

one or more phase difference plates and a diffusion layer provided between the polarizing plate and the 2 nd substrate,

the STN liquid crystal element includes a reflective layer on the 1 st substrate to reflect light transmitted through the color filter;

the color filter is formed by a color resist obtained by blending 5-120% of a pigment into a photosensitive resin, and has a maximum transmittance of 80% or more, a minimum transmittance of 20-50%, and a thickness of 0.5-2.0 μm.

8. The reflective color liquid crystal display device of claim 7, wherein: the color filter is composed of 3 color filters of a red color filter, a green color filter and a blue color filter, or any one of two sets of 3 color filters of a cyan color filter, a magenta color filter and a yellow color filter.