JP2003140135A - Color filter for liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the light utilization efficiency by utilizing the oblique- incident light, in a transmission type liquid crystal display device. SOLUTION: Reflection of the external light can be reduced without damaging the light reutilizing effect by selective reflection of the light from a light source and color change of the oblique-incident light can be eliminated by incorporating the peaks except for wavelength of the transmitted light among the peak wavelengths of three primary colors of the light source of a backlight 24 into a reflection wavelength region of a cholesteric color filter layer 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a flat non-emissive type display, and more particularly, to a color filter when a transmission type liquid crystal display device uses a selective transmission reflection type color filter instead of an absorption type color filter. Is related to the structure of.

[0002]

2. Description of the Related Art In recent years, monochrome or color liquid crystal display devices (LCD) have been used as flat displays. Color liquid crystal display devices include an active matrix system and a simple matrix system for controlling the three primary colors, and a micro color filter is used in each system. In the liquid crystal display device, the constituent pixel portion is a sub-pixel of three primary colors (R, G, B), and the amount of transmitted light of each of the three primary colors is controlled by using the phase change of the liquid crystal due to electrical switching. Color display is performed.

As shown in FIG. 7, the color filter 10 includes, for example, a transparent substrate 12 and a colored layer 14 having R, G, and B color patterns, and a black matrix 16 located at the boundary between pixels. A color filter layer including the protective film 18 and the transparent electrode layer 20 is provided. Currently, these color filters are mainly patterned into corresponding pixels using a photo-curable resin in which red, green and blue pigments are dispersed.

The color of the liquid crystal display device is obtained by arranging pixels of three primary colors of red, green and blue and adjusting the light intensity of each pixel. However, when a cold cathode tube is used for the backlight 24, it is originally The white light emission spectrum of the light source is fixed, and as the patterned color filter thereon, an absorption type color filter 10 using a pigment is used for each pixel to absorb excess light and Changing colors. Therefore, the intensity of the light that actually appears on the surface of the display is
The polarizing plate 26 halves the intensity, and the color filter 10 absorbs ⅔ of the energy thereof, so that the intensity of the backlight 24 is ⅙ or less.

In recent years, in order to improve this point, a cholesteric liquid crystal is used to selectively transmit only a part of light in the visible region by interference of light and reflect the other part to a part of a backlight light source. Methods have been developed to return and reuse.

In this case, as shown in FIG. 8, a semi-transmissive semi-reflective plate 28 of circularly polarized light is placed on the backlight 24 instead of the polarizing plate 26, and the light reaching the liquid crystal cell 30 is rotated to the right. Alternatively, only left-handed circularly polarized light is reflected and the rest is reflected to the light source portion for reuse, and of the right-handed circularly polarized light that has passed through, the color other than the color to be passed by the color filter 10 is reflected and reused.
For example, in the red color filter section 14R, only red right-handed circularly polarized light is transmitted and green and blue right-handed circularly polarized light is reflected, and in the blue color filter section 14B, only blue right-handed circularly polarized light is transmitted. The reflection wavelength is adjusted by cholesteric liquid crystal or chiral nematic liquid crystal so that the right-handed circularly polarized light of green and red is reflected. In this case, the color filter 10
May be a single layer in which the spiral pitch inside is not constant and is changed in the film, or may be a layer in which layers of different one spiral pitch are laminated in the thickness direction.

Such a non-absorption type color filter is
It uses light interference to transmit and reflect. In the cholesteric liquid crystal, the wavelength of reflected light can be arbitrarily changed from ultraviolet to infrared by controlling the chiral pitch at the time of curing.

Further, in order to perform color display without parallax, it is indispensable to place the color filter 10 in the liquid crystal cell 30, and in order to utilize the light that is circularly polarized and colored as it is, A method has been developed in which the driving mode is set to a birefringence mode and the phase is shifted by π when a voltage is applied and when no voltage is applied.

In this method, a quarter-wave plate 32 is formed outside the liquid crystal cell 30 and finally returned to linearly polarized light.
A black and white display is performed by the linear polarizing plate 34.

In the birefringence mode of such a liquid crystal display, when a voltage is applied to the liquid crystal cell 30, the incoming circularly polarized light passes through without change. On the other hand, when no voltage is applied to the liquid crystal cell 30, the right-handed circularly polarized light changes to the left-handed circularly polarized light and the left-handed circularly polarized light changes to the right-handed circularly polarized light because the phase shifts by π. By inserting the quarter-wave plate 32 after the liquid crystal cell 30 and before the linearly polarizing plate 34, the right-handed circularly polarized light and the left-handed circularly polarized light become linearly polarized lights that are orthogonal to each other, and thus are separated by the linearly polarizing plate 32. can do. By adjusting the orientation of the linearly polarizing plate 34, it is possible to display white when a voltage is applied and black when no voltage is applied, and conversely, black when a voltage is applied and white when no voltage is applied.

With this method, however, the transmitted light from the backlight 24 can be turned on and off with good contrast, but conversely, the external light from the side viewed by the human is a complementary color to the color of the color filter 10. The problem is that it is reflected at. Therefore, there is no problem in use in a dark place, but by preventing reflection of these external light, in order to obtain an LCD with higher contrast even in a bright place, it is necessary to add an antireflection function to the color filter.
The applicant has proposed in Japanese Patent Laid-Open No. 2000-347179.

According to this method, it is possible to effectively use the light of the backlight of the liquid crystal display device and prevent the reflection of external light.

[0013]

However, the cholesteric liquid crystal reflects light having a specific spiral pitch with respect to light perpendicular to the formed plane, but with respect to light incident at an angle. There is a property that the wavelength range of reflection is shifted.

Although the backlight currently used in LCDs is designed to increase the brightness in the front direction, there is an angular distribution of emitted light, so that light that enters from an oblique direction exits as it is. However, there is a problem that the utilization efficiency of light is reduced.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a color filter for a liquid crystal display device which can effectively utilize even obliquely incident light. .

[0016]

According to the present invention, a cholesteric color filter formed by using a cholesteric liquid crystal or a chiral nematic liquid crystal that is patterned and transmits light of different specific wavelengths. Layer and a color filter for a liquid crystal display device having a pigment dispersion type color filter layer transmitting the light transmitted through the cholesteric color filter layer on the viewer side with respect to the cholesteric color filter layer, The above object is achieved by a color filter characterized in that the reflection wavelength range includes peaks other than the wavelengths that are transmitted, among the peak wavelengths of the three primary colors of the light source of the backlight.

Here, the cholesteric color filter layer is composed of three types of pixels that transmit light corresponding to the three primary colors of RGB light, and red is provided on the backlight side of the red pigment dispersion type color filter layer. Transparent, 54
It has a cholesteric color filter layer that reflects light in a wavelength range including 5 nm and 435 nm light, and a green pigment-dispersed color filter layer has a wavelength of 610 nm and 435 nm that transmits green light on the backlight side. A cholesteric color filter that has a cholesteric color filter layer that reflects light in the range, and that transmits blue light on the backlight side of the blue pigment-dispersed color filter layer and that reflects light in the wavelength range that includes light of 610 nm and 545 nm. It may have a filter layer.

Further, the cholesteric color filter layer is composed of three kinds of pixels which transmit light corresponding to the three primary colors of RGB light, and red is transmitted to the backlight side of the red pigment dispersion type color filter layer. 545n
m has a cholesteric color filter layer that reflects light in a wavelength range including 435 nm light, and the green pigment-dispersed color filter layer has a wavelength of 610 nm or 435 nm that transmits green light on the backlight side. A cholesteric color filter that has a cholesteric color filter layer that reflects light in a range, and that transmits blue light on the backlight side of the blue pigment-dispersed color filter layer and that reflects light in a wavelength range that includes light of 610 nm or 545 nm. It may have a filter layer.

The cholesteric color filter layer is composed of three types of pixels that transmit light corresponding to the three primary colors of RGB light. Red light is transmitted to the backlight side of the red pigment dispersion type color filter layer. 545 nm
Has a cholesteric color filter layer that reflects light in a wavelength range that includes light of a wavelength range that includes light of a wavelength range that includes 435 nm light on the backlight side of the green pigment-dispersed color filter layer. And a cholesteric color filter layer that transmits blue light and reflects light in a wavelength range including 610 nm light on the backlight side of the blue pigment dispersion type color filter layer. be able to.

The present invention also provides a liquid crystal display device including the color filter.

FIG. 1 shows an example of the structure of the color filter according to the present invention. As described above, the pigment-dispersed C is provided above the ordinary cholesteric color filter (abbreviated as CF) 40.
By creating F42, light of a desired color is transmitted, but other light can be absorbed, and the effect of light reuse by selective reflection of light from the light source side is not impaired, and external light is not impaired. The reflection of light can be reduced and the color change of oblique light can be eliminated.

Although FIG. 2 is a simple explanatory view, as described above, the wavelength range of reflection shifts to the lower wavelength side as the light angle deviates from the direction perpendicular to the plane. Therefore, at a certain angle or more, the light from the light source of the backlight cannot be reflected, and the light utilization efficiency is reduced. Therefore, in the present invention, the reflection band of the cholesteric CF 40 is controlled so as to include many wavelength peaks of the light source of the backlight.
Desirably, even when light enters from the vertical direction, the lower wavelength limit wavelength of the reflection wavelength range of the cholesteric CF is made slightly lower than that by including the wavelength peak of the backlight. It is possible to effectively reflect the light incident on.

When used in a transmissive liquid crystal, the brightness can be improved by forming a cholesteric CF 40 that transmits / reflects light of different wavelengths behind the pigment-dispersed CF 42 of each color of RGB. as,
There are the following three types.

Case 1. As shown in FIG. 1, a red R transmissive / cyan C reflective cholesteric CF 40R is arranged behind the pigment-dispersed CF red 42R, and the pigment-dispersed CF green 4 is formed.
When cholesteric CF40G of green G transmission / magenta M reflection is arranged behind 2G and blue B transmission / yellow Y reflection cholesteric CF40B is arranged behind blue 42B of pigment dispersion CF.

In this case, the red transmission / cyan reflection cholesteric CF40R includes the light of 545 nm and the light of 435 nm in the reflected light band, and when the reflected band is continuous,
It is desirable to include light of 435 nm near the low wavelength side of the reflection band. Cholesteric CF4 with green transmission / magenta reflection
OG includes light of 610 nm and light of 435 nm in the reflected light band, and two reflection bands each include 610 n near the low wavelength side.
It is desirable to include m and 435 nm light. Blue transmission / yellow reflection cholesteric CF40B is 610nm and 545
It is desirable to include the light of wavelength nm in the reflected light band, and to include the light of 545 nm in the vicinity of the low wavelength side of the reflection band when the reflection band is continuous.

Case 2. As shown in FIG. 3, pigment dispersion type C
A cholesteric CF40M that transmits magenta M / reflects green G is placed behind the red 42R of F, and the pigment-dispersed CF green 4
Cholesteric CF with yellow Y transmission / blue B reflection behind 2G
40Y is arranged, and the cyan C transmission / red R reflection cholesteric CF 40C is arranged behind the pigment-dispersed CF blue 42B.

In this case, it is desirable that the magenta transmission / green reflection cholesteric CF 40M include light of 545 nm near the low wavelength side of the reflection band. It is desirable that the yellow transmission / blue reflection cholesteric CF 40Y include light of 435 nm near the low wavelength side. The cyan transmission / red reflection cholesteric CF40C preferably includes 610 nm near the low wavelength side of the reflection band.

Case 3. As shown in FIG. 4, pigment dispersion type C
Yellow Y transmission / blue B reflection cholesteric CF40Y is arranged behind F red 42R, and cyan C transmission / red R reflection cholesteric CF4 is arranged behind pigment dispersion type CF green 42G.
0C is arranged, and magenta M transmission / green G reflection cholesteric CF 40M is arranged behind the blue 42B of the pigment dispersion type CF.

In this case, it is desirable that the yellow transmission / blue reflection cholesteric CF 40Y include light of 435 nm near the low wavelength side. Cholesteric C with cyan transmission / red reflection
F40C preferably includes 610 nm near the low wavelength side of the reflection band. The magenta transmissive / green reflective cholesteric CF40M preferably includes light of 545 nm near the low wavelength side of the reflection band.

In the cases 2 and 3, the efficiency of light reuse by the cholesteric layer is lowered, but the cholesteric layer can be formed by one layer, which has an advantage that the process can be shortened and simplified. In this case, Case 2 is preferable in that the color of the pigment-dispersed CF originally formed thereon, which is originally transmitted, is not affected when the reflection wavelength shifts to the low wavelength region.

[0031]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 5, the transmissive liquid crystal display device 50 of the left-handed circularly polarized light absorption type and the right-handed circularly polarized light transmission type according to the first embodiment of the present invention includes red, green and blue wavelength light beams. A back light 24 that emits a back light including light, and a selective transmission / reflection type color filter (CF) 10 that is patterned for each pixel and that transmits only the corresponding wavelength light of red, green, and blue and reflects the other. , A quarter-wave plate 52 and a linear polarizing plate 54 arranged so as to face the light exit surface of the backlight 24.
And a liquid crystal cell 30 of, for example, a TFT.

The color filter 10 and the liquid crystal cell 30
Are sandwiched between a pair of glass substrates 12 and 31 and arranged.

As the backlight 24, for example, a uniform planar light-emitting body including a diffusion plate 24B having a cold cathode tube 24A as a light source is used, and a metal thin film is formed on the back side (lower side in FIG. 5). The reflective layer 24C made of is disposed.

The quarter wave plate 52 and the linear polarizing plate 54
Constitutes a dichroic circularly polarizing plate 56 that absorbs left-handed circularly polarized light and transmits right-handed circularly polarized light.

The liquid crystal cell 30 has a birefringence control (EC) for controlling the birefringence of the liquid crystal layer by applying an electric field.
B) type, which includes a VAN system, a PAN system, a HAN system, and the like, and the phase shift amount of transmitted light becomes 0 or π by turning on / off an applied voltage.

As shown in the enlarged view of FIG. 1, the color filter 10 includes a cholesteric CF 40, a pigment dispersion type CF 42 formed on the light emitting surface side thereof, and a black matrix 16.

The cholesteric CF 40 is composed of a cholesteric liquid crystal layer or a chiralmatic liquid crystal layer laminated on the glass substrate 12.

The pigment-dispersed CF 42 is patterned for each pixel in the same manner as the cholesteric CF 40.
In addition, it is formed by dispersing a pigment or dye of a required color in a photocurable transparent resin.

In the present invention, as shown in FIG. 1, the color filter 10 includes, in the reflection wavelength range of the cholesteric CF 40, peaks other than the wavelengths of the three primary colors of the light source of the backlight 24 other than the wavelengths that are transmitted. I am trying to do it.

Specifically, as in claim 2, the cholesteric CF 40 is composed of three types of pixels which transmit light corresponding to the three primary colors of RGB light, and the back of the red pigment dispersion type CF layer 42R. The light side has a cholesteric CF layer 40R that transmits red light and reflects light in a wavelength range including light of 545 nm and 435 nm close to the low wavelength region side end of the reflection region, and has a green pigment dispersion type. On the backlight side of the CF layer 42G, green is transmitted,
A blue pigment-dispersed CF layer 4 having a cholesteric CF layer 40G that reflects light in a wavelength range including light of 10 nm and 435 nm near a low wavelength region side end of a reflection region.
Blue light is transmitted to the backlight side of 2B, and is 610 nm.
And a cholesteric C that reflects light in a wavelength range including light having a wavelength of 545 nm close to the low wavelength region side end of the reflection region.
It has an F layer 40B.

Alternatively, as described in claim 3, the cholesteric CF layer 40 is composed of three types of pixels that transmit light corresponding to the three primary colors of RGB light, and the backlight of the red pigment dispersion type CF layer 42R. The side has a cholesteric CF layer that transmits red and reflects light in a wavelength range including light of 545 nm or 435 nm, and the backlight side of the green pigment dispersion type CF layer 42G transmits green. A blue pigment-dispersed CF having a cholesteric CF layer that reflects light of a wavelength range including 610 nm or 435 nm light close to the low wavelength region side end of the reflection region.
On the backlight side of the layer 42B, blue is transmitted,
a cholesteric CF layer that reflects light in a wavelength range including light having a wavelength of nm or 545 nm close to the low wavelength region side end of the reflection region.

Alternatively, as in claim 4, the cholesteric CF layer 40 is composed of three types of pixels that transmit light corresponding to the three primary colors of RGB light, and the backlight of the red pigment dispersion type CF layer 42R. The side has a cholesteric CF layer that transmits red light and reflects light in a wavelength range including light of 545 nm in the vicinity of the low wavelength region side end of the reflection region, and has a green pigment dispersion type CF layer 42G. The backlight side has a cholesteric CF layer that transmits green light and reflects light in a wavelength range including 435 nm light near a low wavelength side end of a reflection region, and a blue pigment-dispersed CF layer. The backlight side of 42B transmits blue color,
It has a cholesteric layer that reflects light of a wavelength range including light of 610 nm in the vicinity of the low wavelength region side end of the reflection region.

In this way, by including peaks other than the wavelengths that are transmitted among the peak wavelengths of the three primary colors of the light source of the backlight 24, it is possible to effectively reflect even obliquely incident light.

Next, a right-handed circularly polarized light transmission type and a left-handed circularly polarized light reflection type transmission type liquid crystal display device according to the second embodiment of the present invention will be described in detail with reference to FIG.

In this embodiment, in a liquid crystal display device similar to that of the first embodiment, between the backlight 24 and the color filter 10, as in Japanese Patent Laid-Open No. 2000-347179,
By providing the circularly polarized light separating film 62, the left-handed circularly polarized light is reused.

The circularly polarized light separating film 62 reflects left-handed circularly polarized light and transmits right-handed circularly polarized light.

On the back side (lower side in FIG. 6) of the diffuser plate 24B of the backlight 24, a reflective layer 24C made of a metal thin film is arranged similarly to the above.

The reflection layer 24C reflects the left-handed circularly polarized light component emitted from the diffusion plate 24B and reflected by the circularly polarized light separating film 62 toward the circularly polarized light separating film 62 again, and at this time, the phase of the polarized light component is inverted. Alternatively, or in a non-polarized state, the light utilization rate is improved by making all or part of the right-handed circularly polarized light component that can be transmitted through the circularly polarized light separating film 62.

In the present embodiment, the circularly polarized light separating film 62 transmits right-handed circularly polarized light and reflects left-handed circularly polarized light. The birefringent film is laminated in three or more layers. The 1/4 wavelength layer is laminated on this so that the fast axis or the slow axis has an angle of 45 degrees. The film having birefringence as described above can be obtained by stretching a substance such as polycarbonate resin, polyester resin, polyvinyl alcohol resin, or the like, which exhibits in-plane birefringence.

As the circularly polarized light separating film 62, a cholesteric liquid crystal is used, and by making the cholesteric liquid crystal have a spectrum, it is possible to reflect right-handed circularly polarized light in all regions of visible light. .

According to this embodiment, the cholesteric CF
The strength improvement by 40 is doubled, and the strength improvement by reusing the left-handed circularly polarized light is doubled, resulting in a total of 2 × 2 = 4 times.

[0053]

EXAMPLES (1) Case 1 First, in order to prepare a cholesteric liquid crystal color filter, a black pigment-dispersed photocurable resin is applied on a non-alkali glass substrate in an amount of 1.5 μm, and a black matrix is formed using a photomask. Exposure. Then, by performing alkali development, a black matrix pattern was formed.

Next, a photocurable cholesteric liquid crystal was added to 5 μm.
m and apply the temperature at the low wavelength end of cholesteric reflection of 43
Adjust to 0 nm, and use a photomask to make RG
One pixel portion of B was exposed. As a result, a cholesteric layer having a reflection wavelength range of 430 to 500 nm could be formed.

After that, the temperature was changed to adjust the low wavelength end of the cholesteric reflection to 520 nm, and the remaining two pixel portions were entirely exposed. Thereby, a cholesteric layer having a reflection wavelength range of 520-600 nm was formed.

Further, a photocurable cholesteric liquid crystal is applied thereon to a thickness of 5 μm, and mask exposure is performed in the same manner, so that a portion corresponding to one pixel having a low wavelength side reflection wavelength end of 430 nm and a low wavelength side reflection wavelength end of 600 nm are obtained. A pattern for 2 pixels adjusted to 1 was formed. Thereby, the reflection wavelength range 430 to 50
Cholesteric layers of 0 nm and 600-700 nm were formed. At this time, by shifting the upper and lower patterns by one pixel, one pixel reflects R and G and transmits only B, and one pixel reflects R and B and transmits only G,
In a certain pixel, G and B could be reflected and only R could be transmitted.

Further, a red pigment-dispersed photocurable resin was applied thereon to a thickness of 1 μm, and a photomask was used to form a red filter only on the red transmissive part of the cholesteric CF. By repeating the same procedure for each of green and blue, it was possible to finally form a composite color filter having a cross section as shown in FIG.

With this color filter, a circularly polarized light separating film for transmitting circularly polarized light in the direction of reflection of a cholesteric color filter on a normal cold cathode ray tube backlight and reflecting different circularly polarized light as in the second embodiment. When 62 was installed and the brightness was measured, as shown in FIG. 7, it was possible to obtain a brightness of 2.8 times as high as that of the color filter prepared by only dispersing the pigment without forming the cholesteric layer. Further, when the cholesteric reflection wavelength range was set to 535 nm, 545 nm, and 610 nm with the center of the reflection wavelength range being 535 nm, 545 nm, and 610 nm, respectively, the increase in luminance was 2.4 times, and the effect of obliquely incident light was observed.

(2) Case 2 First, in order to prepare a cholesteric liquid crystal color filter, a black pigment-dispersed photocurable resin is applied on a non-alkali glass substrate in a thickness of 1.5 μm and a photomask is used to form a black matrix. Exposed. Then, by performing alkali development, a black matrix pattern was formed.

Next, a photocurable cholesteric liquid crystal was added to 5 μm.
m and apply the temperature at the low wavelength end of cholesteric reflection of 43
Adjust to 0 nm, and use a photomask to make RG
One pixel portion of B was exposed. As a result, a cholesteric layer having a reflection wavelength range of 430 to 500 nm could be formed.

After that, the temperature was changed so that the low wavelength end of cholesteric reflection was adjusted to 520 nm, and one pixel was exposed. Thereby, the reflection wavelength range 520-60
A 0 nm cholesteric layer was formed.

Further, the last one pixel portion was formed by adjusting the reflection wavelength end on the low wavelength side to be 600 nm.
As a result, a cholesteric layer having a reflection wavelength range of 600 to 700 nm was formed, and three types of pixels having reflected light of RGB three colors could be formed.

Further, a red pigment-dispersed photocurable resin was applied thereon to a thickness of 1 μm, and a red filter was formed only on the red transmission part of the cholesteric CF using a photomask. By repeating the same procedure for each of green and blue, it was possible to finally form a composite color filter having a cross section as shown in FIG.

A circularly polarized light separating film for transmitting circularly polarized light in the reflecting direction of a cholesteric color filter on a normal cold cathode ray tube backlight and reflecting different circularly polarized light by using this color filter as in the second embodiment. When 62 was installed and the brightness was measured, as shown in FIG. 7, 1.4 times the brightness could be obtained with respect to the color filter prepared only by dispersing the pigment without forming the cholesteric layer. Also, when the reflection wavelength range of the cholesteric was set to 535 nm, 545 nm, and 610 nm at the centers of the reflection wavelength ranges, the increase in brightness was 1.2 times, and the effect of obliquely incident light was observed.

[0065]

Since the present invention is constructed as described above,
By utilizing the oblique light and controlling the wavelength of the backlight, there is an excellent effect that the light utilization efficiency can be increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a composite color filter showing an example of the main configuration of the present invention.

FIG. 2 is a spectrum diagram showing the amount of the relationship between the reflection wavelengths of the backlight and the selective reflection color filter in the present invention.

FIG. 3 is a sectional view of a composite color filter showing another example of the main configuration of the present invention.

FIG. 4 is a cross-sectional view of a composite color filter showing still another example of the main configuration of the present invention.

FIG. 5 is a schematic cross-sectional view showing a transmissive liquid crystal display device according to the first embodiment of the invention.

FIG. 6 is a schematic sectional view showing a second embodiment of the same.

FIG. 7 is a sectional view of an example of a conventional color filter.

FIG. 8 is a sectional view of another example of a conventional color filter.

[Explanation of symbols]

10 ... Color filter 24 ... Backlight 30 ... Liquid crystal cell 32 ... Quarter wave plate 34 ... Linearly polarizing plate 40 ... Cholesteric color filter (CF) 42 ... Pigment dispersion type color filter (CF) layer 62 ... Circularly polarized light separating film

Claims (5)

[Claims] 1. A cholesteric color filter layer formed by using a cholesteric liquid crystal or a chiral nematic liquid crystal that is patterned and transmits light of different specific wavelengths, and transmits the light transmitted by the cholesteric color filter layer. A color filter for a liquid crystal display device having a pigment-dispersed color filter layer on the observer side with respect to the cholesteric color filter layer, wherein the peak wavelengths of the three primary colors of the light source of the backlight are within the reflection wavelength range of the cholesteric color filter layer. Among them, a color filter for a liquid crystal display device, which includes a peak other than a wavelength to be transmitted. 2. The cholesteric color filter layer according to claim 1, wherein the cholesteric color filter layer is composed of three types of pixels that transmit light corresponding to the three primary colors of RGB light, and is provided on the backlight side of the red pigment dispersion type color filter layer. Has a cholesteric color filter layer that transmits red light and reflects light in a wavelength range including light of 545 nm and 435 nm,
On the backlight side of the green pigment-dispersed color filter layer, there is provided a cholesteric color filter layer that transmits green and reflects light in a wavelength range including light of 610 nm and 435 nm, and a blue pigment-dispersed color filter layer. The blue light is transmitted to the backlight side of 610 nm and 545 nm.
A color filter for a liquid crystal display device, comprising a cholesteric color filter layer that reflects light in a wavelength range including light of nm. 3. The cholesteric color filter layer according to claim 1, wherein the cholesteric color filter layer is composed of three types of pixels that transmit light corresponding to three primary colors of RGB light, and is disposed on the backlight side of the red pigment dispersion type color filter layer. Has a cholesteric color filter layer that transmits red light and reflects light in a wavelength range including light of 545 nm or 435 nm, and transmits green light to the backlight side of the green pigment dispersion-type color filter layer and transmits 610 nm. Alternatively, it has a cholesteric color filter layer that reflects light in a wavelength range including light of 435 nm, and the blue side is transmitted to the backlight side of the blue pigment dispersion type color filter layer, and a wavelength range that includes light of 610 nm or 545 nm. For a liquid crystal display having a cholesteric color filter layer that reflects the Filter. 4. The cholesteric color filter layer according to claim 1, wherein the cholesteric color filter layer is composed of three types of pixels that transmit light corresponding to three primary colors of RGB light, and is disposed on the backlight side of the red pigment dispersion type color filter layer. Has a cholesteric color filter layer that transmits red light and reflects light in a wavelength range including 545 nm light, and transmits green light to the backlight side of the green pigment dispersion type color filter layer and transmits 435 nm light. Including a cholesteric color filter layer that reflects light in a wavelength range including a cholesteric color filter layer that transmits blue light and reflects light in a wavelength range that includes 610 nm light on the backlight side of the blue pigment dispersion type color filter layer. A color filter for a liquid crystal display device having a color filter layer. 5. A liquid crystal display device comprising the color filter according to claim 1.