JP4494110B2 - Color display device - Google Patents

Description

  The present invention relates to a color display device, and is particularly suitable for a color liquid crystal display device.

  Conventionally, many color liquid crystal display devices have been used as color displays having features such as thinness and light weight.

  Among this kind of color liquid crystal display device, the reflective color liquid crystal display device uses ambient light, and therefore has the characteristics that the power for the backlight can be reduced and the space and weight of the backlight can be saved. In addition, the display quality when the surroundings are very bright such as in direct sunlight is superior to that of the transmissive color liquid crystal display device. On the other hand, since the transmissive color liquid crystal display device has a backlight, the display quality in a relatively dark environment such as a room is superior to that of the reflective color liquid crystal display device.

  In view of the above, mobile terminals such as mobile phones and PDAs have a reflective / transmissive color liquid crystal display device having a reflective portion and a transmissive portion in each pixel, or a reflective color liquid crystal display device having a front light. Two types of color liquid crystal display devices are widely used.

  Currently, a color liquid crystal display device is widely used in a system using two or one polarizing plate. In a color liquid crystal display device, a twisted nematic mode (hereinafter referred to as “TN mode”) in which display is performed by controlling the optical rotation of the liquid crystal layer by an electric field, and a birefringence mode in which display is performed by controlling the birefringence of the liquid crystal layer by an electric field. (Hereinafter, referred to as “ECB mode”) or a mixed mode in which the TN mode and the ECB mode are combined is mainly used.

  However, color liquid crystal display devices using these modes generally have a very low light use efficiency of 10% or less. The main causes for greatly reducing the light utilization efficiency are the polarizing plate and the absorption type color filter. When a polarizing plate is used, only about 45% of light can be used. When an absorption color filter is used, only about 30% of light can be used for the transmission type and about 50% for the reflection type. Here, the utilization efficiency differs between the transmission type and the reflection type. The reflection type uses a light color filter with a light color density reduced to increase the reflectance. Because.

  Focusing on this point, in order to improve the light utilization efficiency, several methods have been proposed so as not to use a polarizing plate or a color filter that significantly reduces the light utilization efficiency.

  One method does not use a polarizing plate. Examples of this method include a guest-host method in which a dye is mixed in a liquid crystal layer and a color liquid crystal display device using a polymer-dispersed liquid crystal.

  As another method, a color filter is not used. Examples of this method include a method using a cholesteric liquid crystal and a color liquid crystal display device of a field sequential method.

  However, the guest host method, the method using polymer dispersed liquid crystal, and the method using cholesteric liquid crystal have problems such as a low contrast ratio and a high driving voltage. Further, the field sequential method is advantageous in this respect because a conventional liquid crystal layer is used for the driving part, but is disadvantageous because in principle a problem of color braking occurs.

  Although not intended to improve the reflectivity of the reflective color liquid crystal display device, it is mainly intended to expand the color reproduction range, and uses a phosphor that converts color. One that performs color display is known (for example, Patent Document 1 and Patent Document 2).

  The transmissive color liquid crystal display panel described in Patent Document 1 has a color balance and a viewing angle characteristic by arranging a phosphor for converting color and a color purity improving filter on the front surface (viewer side) of the liquid crystal panel. It aims to improve and expand the color reproduction range. However, when the phosphor is arranged on the front surface (viewer side) of the panel in this way, it emits fluorescence when ambient light is incident, so that a good black display is not realized and the display quality is remarkably lowered.

  In addition, the reflection / transmission type liquid crystal display device described in Patent Document 2 has a purpose of disposing a color conversion layer on a rear substrate and further expanding a color range when an auxiliary light source is turned on in a dark environment. .

However, in such a liquid crystal display device, the light emitted from the color conversion layer by the light of the auxiliary light source positioned below passes through the auxiliary aperture light source unit and is reflected by the first reflecting plate provided on the upper substrate. However, this reflected light passes through the color filter of each pixel, is reflected again by the second reflecting plate provided on the lower substrate, and reaches the viewer side on the front side. As described above, only the light that passes through the auxiliary aperture light source part among the light emitted by the color conversion layer can be used, so that it can only be used as an auxiliary light source, and the light that has passed through the auxiliary aperture light source part can also be used. Reflection by the reflecting plate was performed twice, and the light utilization efficiency was insufficient by passing through the color filter twice.
JP-A-4-12323 JP 2001-133770 A

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a color liquid crystal display device that greatly improves the light use efficiency without deteriorating the display quality.

The present invention has been made to solve the above-mentioned problems, and a color display device according to the first aspect of the present invention includes a front substrate on which at least color filter means and a transparent electrode are formed, at least a transparent electrode, A liquid crystal layer is sandwiched between the phosphor layer and the back side substrate on which the reflecting means is formed, and reflects the external light as incident light, so that light of a desired color is reflected on the viewer side in each pixel. in the color display device so provided as to supply to, the pixels for supplying a specific color, the phosphor layer is provided to convert the light other than the specific color of the incident light to a particular color, the The reflection means uses a retroreflective layer that converges from the light opening on the viewer side to the bottom on the opposite side of the viewer, and the phosphor layer is formed only near the bottom of the retroreflective layer. to become And butterflies.

  In the color display device having the above configuration, when external light (incident light) reaches the phosphor layer, light other than the specific color is converted into the specific color by the phosphor layer. Become. That is, for example, the phosphor layer in a pixel that supplies green to the viewer side (hereinafter sometimes referred to as a green pixel; the same applies to red and blue) converts the blue component of light into a green component. By providing in, the blue component of the external light reaching the phosphor layer can also be used for green display. For this reason, in the conventional configuration, the incident light that has been absorbed by the color filter and lost as thermal energy can be used for color display, and light utilization efficiency can be improved.

  In the color display device having the above-described configuration, it is preferable that the pixel is provided with color filter means that does not allow light of a certain color that cannot be converted into the specific color of the incident light by the phosphor layer. .

  By adopting the above configuration, a certain color that cannot be converted into a specific color in the phosphor layer can be absorbed by the color filter means, so that a desired specific color can be clearly displayed in each pixel. That is, for example, when the phosphor layer in the green pixel converts the blue component of light into a green component but cannot convert the red component into green, by providing color filter means that absorbs the red component in the green pixel The blue component of the external light is also used for green display, and the red component light is absorbed, so that the green pixel can be accurately displayed in green.

The color display device according to the second aspect of the present invention is provided so as to supply red light, green light and blue light to the viewer side in each pixel by reflecting external light as incident light. In the color display device, a pixel that supplies red is provided with a phosphor layer that converts blue light and green light of incident light into red, and the pixel that supplies green is incident A phosphor layer that converts the blue component of the light into green is provided, and a color filter layer that does not allow the red component to pass through is provided. Color filter means that does not allow light of the components to pass therethrough is provided.

  In the color display device having the above configuration, it is possible to use the part of the external light that has been absorbed by the color filter and lost as heat energy in the conventional configuration for color display. Efficiency can be improved. More specifically, the external light that has reached the phosphor layer of the red pixel is also converted into red light by the phosphor layer, and the green light and the blue component are also out of the external light that has reached the phosphor layer of the green pixel. The blue component is converted into green light by the phosphor layer, and therefore, an external light component that has not been conventionally used can also be used for displaying a desired color.

  Further, since a desired color filter means is provided in each pixel, a desired specific color can be clearly displayed in each pixel. In other words, since the green pixel is provided with color filter means that does not allow the red component to pass through, the green display can be accurately performed without the light of the red component being mixed with the green display. Further, since the blue pixel is provided with a color filter means that does not allow the red component and green components to pass through, the red and green components do not mix with the blue display, and the blue pixel is accurately displayed. be able to.

  In the color display device having the above-described configuration, the pixel that supplies red has a smaller area than the pixel that supplies other colors, and the pixel that supplies green has a smaller area than the pixel that supplies blue. It is preferable to adopt a configuration having a small area.

  In other words, if the pixels of each color have the same area, the red color with the highest light utilization efficiency is generally stronger than the other colors. Therefore, by adopting the above configuration, the white balance is adjusted as a whole. Display can be realized.

  Moreover, in this invention, it is preferable to employ | adopt the structure by which the fluorescent substance layer is provided so that the light of an ultraviolet component among incident light may be converted into a specific color. Specifically, in the blue pixel, by providing a phosphor layer that converts the light of the ultraviolet component of the incident light into a specific color, the light can be effectively used in the blue pixel. The phosphor layer that converts the light of the ultraviolet component into a specific color can also be provided in the red pixel and the green pixel, and may be provided in all of the pixels of each color or only in a specific one. This is a matter that can be changed.

  Further, the color filter means can be composed of, for example, a color filter layer obtained by coating and curing a light absorbing material in a resin, and mixing the light absorbing material together with the fluorescent material when forming the phosphor layer. It is also possible to comprise a phosphor layer.

  Moreover, in the color display device according to the present invention, the viewer has a liquid crystal layer on the viewer side of the phosphor layer, and the liquid crystal layer has a liquid crystal molecule alignment direction. Is composed of twisted nematic liquid crystal twisted by 90 degrees, and a configuration in which a polarization applying means for converting non-polarized light into polarized light is provided between the liquid crystal layer and the phosphor layer can be adopted. . In the case of adopting such a configuration, the external light is converted into polarized light by the polarization applying unit, and is emitted to a desired color in the phosphor layer, and this emitted light is again emitted from the polarization applying unit and the liquid crystal layer. Will be supplied to the observer side.

The color display device according to the present invention is characterized in that a reflecting means is provided on the opposite side of the phosphor layer from the viewer . Thereby, among the light emitted in the phosphor layer, the light emitted on the opposite side of the viewer is reflected on the viewer side by the reflecting means, and the light utilization efficiency can be further increased.

In addition, the color display device according to the present invention is characterized by having a reflecting means composed of a retroreflective layer that reflects light emitted from the fluorescent layer to the viewer side . Thereby, the light emitted in the phosphor layer is more accurately reflected toward the viewer side, and the light utilization efficiency can be further increased.

  Various retroreflective layers such as a bead type can be used, but a corner cube type is preferably used.

Further, in the case of having the retroreflective layer as described above, the retroreflective layer is provided so as to converge from the light opening on the viewer side to the bottom on the opposite side of the viewer, A phosphor layer is provided near the bottom of the reflective layer . Thereby, outside light that has reached the reflective layer near the phosphor layer is reflected by the reflective layer toward the bottom phosphor layer, thereby increasing the probability that the external light reaches the phosphor layer, Of the light emitted from the phosphor layer, the light emitted in the lateral direction (perpendicular to the viewer) is also reflected toward the viewer by the reflective layer, further improving the light utilization efficiency. be able to.

  Moreover, when it has a reflection means as mentioned above, it is preferable to employ | adopt the structure by which the said reflection means is provided so that the light supplied from the other side of a viewer can be permeate | transmitted. Thereby, the light supplied from the opposite side of the viewer can be used. Therefore, a reflective / transmissive color liquid crystal display device can be obtained by installing a backlight or the like.

Further, the color display device according to the present invention has a liquid crystal layer that controls the passage of light in each pixel on the viewer side of the phosphor layer, and the liquid crystal layer has a liquid crystal molecular alignment direction of 90. Twisted nematic liquid crystal, and the phosphor layer is arranged to emit fluorescence with respect to a certain linearly polarized light and not to emit fluorescence with respect to a linearly polarized light orthogonal to the linearly polarized light that emits this fluorescence. A configuration can be adopted. When such a configuration is adopted, the phosphor layer emits light in a desired color by polarized light polarized in a certain direction,
This emitted light passes through the liquid crystal layer and is supplied to the viewer side.

  In the color display device according to the present invention, it is preferable to adopt a configuration in which the phosphor layer is provided so as not to scatter light of a specific color of incident light. Thereby, the color purity can be improved and a clear display can be realized. That is, it is possible to prevent light that has undergone total reflection at the interface among the light emitted from the phosphor layer from reaching the phosphor layer of another pixel and causing mixed color display in this pixel. More specifically, among the light emitted from the phosphor layer of one pixel, the light that has undergone total reflection at the interface is scattered in this phosphor layer when it reaches the phosphor layer of another pixel. In addition, the scattered light and the light that is originally intended to emit light are mixed, and there is a problem that a clear display is impossible. For this reason, as described above, by using a phosphor layer that does not scatter light of a specific color of incident light, even if light that has been emitted by other pixels and caused total reflection reaches this phosphor layer. This has the advantage that it passes through the phosphor layer as it is and does not obstruct display.

  As described above, in the color display device according to the present invention, when incident light that is external light reaches the phosphor layer, light other than the specific color in the external light is converted into a specific color by the phosphor layer. Therefore, in the conventional configuration, the amount absorbed by the color filter and lost as heat energy can be used for color display, and the light use efficiency can be greatly improved. Have.

Hereinafter, embodiments of a color display device according to the present invention will be described with reference to the drawings.
[ Reference Example 1]
FIG. 1 is a schematic cross-sectional view of Reference Example 1 of a color display device according to the present invention.

The reflective color display device of this reference example is provided so as to supply RGB color light to the viewer side in each pixel by reflecting external light as incident light. In the color display device, the liquid crystal layer 3 is sandwiched between a pair of substrates 1 and 2, and the pair of substrates 1 and 2 is optically isotropic such as a transparent glass plate or a polymer film, respectively. It is made of sex material. The pair of substrates 1 and 2 has a transparent electrode 4 (pixel electrode and counter electrode) for applying a voltage to the liquid crystal layer 3 to control the passage of light in each pixel. A horizontal alignment film 5 is formed on the surface of the transparent electrode 4. Further, the front substrate 1 is provided with a polarizing plate 6 on the observer side, and the liquid crystal layer 3 is composed of twisted nematic liquid crystal twisted by 90 degrees in the liquid crystal molecule alignment direction.

In this reference example, as a method for enclosing the liquid crystal layer 3, for example, the following method can be employed. First, a 2% solution of trade name SE-150 (manufactured by Nissan Chemical Industries, Ltd.) as a polyimide on the surface of the transparent electrode 4 was 2000 r.p. p. m. The alignment film 5 is formed by spin coating. Thereafter, the two substrates 1 and 2 on which the alignment film 5 is formed are baked at 150 degrees. And after baking, the surface of the alignment film 5 was subjected to alignment treatment. As the alignment treatment, the surface was rubbed in one direction. The rubbing direction was set to be vertical when the two substrates 1 and 2 were combined. The alignment films 5 of these two substrates 1 and 2 were faced to each other and fixed so that the gap was 4.5 μm. Hereinafter, this gap is referred to as cell thickness. Liquid crystal was sealed in this gap. As a liquid crystal, a trade name ZLI-1565 (manufactured by Merck) of Δn = 0.126 was used.

  In addition, a color filter layer 7 is formed between the transparent substrate 4 (counter electrode) and the front substrate 1 (observer substrate) of the pair of substrates 1 and 2. That is, on the front substrate 1, the color filter layer 7 is formed on the surface of the other substrate 1, 2, and the transparent electrode 4 as the counter electrode 4 is formed on the surface of the color filter layer 7. A horizontal alignment film 5 is formed on the surface of the transparent electrode 4.

  Of the pair of substrates 1 and 2, the back side substrate 2 (the substrate facing the front side substrate 1) has a polarizing layer 8, a phosphor layer 9, and a transparent electrode 4 (pixel electrode). A reflective layer 10 is provided. That is, on the back side substrate 2, the reflective layer 10 is formed on the surface of the other side of the substrate 1, the phosphor layer 9 is formed on the surface of the reflective layer 10, and the polarizing layer is formed on the surface of the phosphor layer 9. 8 is formed, the transparent electrode 4 as the pixel electrode 4 is formed on the surface of the polarizing layer 8, and the horizontal alignment film 5 is formed on the surface of the transparent electrode 4. The reflection layer 10 is composed of a scattering reflection layer that can impart scattering properties.

  In the red pixel, the phosphor layer 9 is provided so as to convert blue component light and green component light of incident light into red, and in the green pixel, blue component light of incident light is converted. The blue pixel is provided so as to convert the ultraviolet component light of the incident light into blue.

In this reference example, for example, trade name FZ-2003 (manufactured by Sinloihi Co., Ltd.) is used as the red phosphor, trade name FZ-2002 (manufactured by Sinloihi Co., Ltd.) is used as the green phosphor, and trade name FZ is used as the blue phosphor. The phosphor layer 9 can be configured by applying -SB (manufactured by Sinloihi Co., Ltd.) with a squeegee.

  Further, the color filter layer 7 transmits, in each pixel, light of a color that the phosphor layer 9 converts into a specific color and a specific color (for example, red in a red pixel), and other visible light colors. The components are provided to absorb. More specifically, in the blue pixel, the color filter layer 7 is provided so as to pass the blue component and the ultraviolet component of the incident light and absorb the red component and the green component. In the green pixel, the color filter layer 7 is provided so as to pass the green component light and the blue component light in the incident light and absorb the red component light.

  In addition, the area ratios of the pixels of the respective colors are different so that the white balance as a whole is adjusted. Specifically, the red pixel has a smaller area than the other color pixels, and the green pixel has a smaller area than the blue pixel. More specifically, the area ratio of each of the red pixel, the green pixel, and the blue pixel is set to 6: 4: 3.

Next, advantages of the above color display device will be described below with reference to FIGS. 2 is a schematic cross-sectional view of a conventional reflective color display device, FIG. 3 is a schematic cross-sectional view of a reflective color display device of Reference Example 1, and arrows indicate light. The reflective display device performs display by reflecting light (external light) incident from the outside of the device. Since the incident light 13 (external light) is white, the red component 13R, the green component 13G, and the blue component are displayed. In the following, it is assumed that the system is composed of 14B. 2 and 3, each pixel is illustrated in the order of a red pixel, a green pixel, and a blue pixel from the left side to the right side.

  First, the conventional color display device will be described. In the conventional reflection type color display device, as shown in FIG. 2, the red component 13R of the incident light 13 incident on the red pixel is transmitted through the color filter layer 7. Then, the light is reflected by the reflective layer 10 and becomes reflected light 14R, which is emitted to the viewer side. The green component 13G and the blue component 13B are absorbed by the color filter layer 7. Similarly, of the incident light 13 incident on the green pixel, the green component 13G is transmitted through the color filter layer 7, reflected by the reflective layer 10, and becomes reflected light 14G, which is emitted to the viewer side. The red component 13R and the blue component 13B are absorbed by the color filter layer 7. Similarly, of the incident light 13 incident on the blue pixel, the blue component 13B is transmitted through the color filter layer 7, reflected by the reflective layer 10, and becomes reflected light 14B, which is emitted to the viewer side. The red component 13R and the green component 13G are absorbed by the color filter layer 7.

On the other hand, in the reflective color display device of the present reference example, the red component 13R of the incident light 13 incident on the red pixel is transmitted through the color filter layer 7 and the phosphor layer 9, and the reflective layer. 10 is reflected to become reflected light 14R, which is emitted to the viewer side. The green component 13G and the blue component 13B are converted into red light by the phosphor layer 9, reflected by the reflective layer 10, and reflected light 14R-1 and 14R-2, which are emitted to the viewer side. Similarly, of the incident light 13 incident on the green pixel, the green component 13G passes through the color filter layer 7 and the phosphor layer 9, is reflected by the reflective layer 10, becomes reflected light 14G, and is emitted to the viewer side. . The blue component 13B is converted into green light by the phosphor layer 9, is reflected by the reflective layer 10, becomes reflected light 14G-1, and is emitted to the viewer side. The red component 13R is absorbed by the color filter. Similarly, of the incident light 13 incident on the blue pixel, the blue component 13B is transmitted through the color filter layer 7, reflected by the reflective layer 10, and becomes reflected light 14B, which is emitted to the viewer side. The red component 13R and the green component 13G are absorbed by the color filter layer 7. The ultraviolet component (not shown) is converted into blue light by the phosphor layer 9, reflected by the reflective layer 10, becomes reflected light (not shown), and is emitted to the viewer side.

  As described above, the use efficiency of light can be improved without degrading display quality by using a phosphor that converts color. In general, a phosphor that converts color is more efficiently converted (ie, color-converted) from a short wavelength to a long wavelength as compared with a conversion from a long wavelength to a short wavelength. The phosphor layer 9 converts the green component light and the blue component light into red, and the phosphor layer 9 of the green pixel converts the blue component light into green so that external light can be displayed efficiently. Can be used.

  In addition, the phosphor layer 9 is also provided in the blue pixel, and light having a wavelength (purple) shorter than the blue component of incident light is converted into blue, so that external light can be used for display more efficiently. Can do.

Next, the measurement results of the optical characteristics of this reference example will be described. FIG. 4 is a diagram for explaining the schematic configuration of the measuring apparatus. In this measuring apparatus, the sample 15 is arranged under the projector 16 on the hemisphere, and the intensity of the reflected light is measured by the luminance meter 17 arranged in the front. Can be measured. Here, assuming that the reflected light intensity when the standard white plate is arranged at the sample position is 100%, the reflectance of the red display, the green display, and the blue display of the reflective display device of the present invention and the conventional reflective display device is as follows. It was measured.

5 and 6 are diagrams showing the above measurement results. FIG. 5 shows the measurement results of the reflective color display device of this reference example, and FIG. 6 shows the measurement results of the conventional reflective color display device. In the conventional reflective color display device, the peak of red display, green display, and blue display is about 8%, but in the reflective color display device of this reference example, the peak of red display, green display, and blue display is 12%. It is apparent that the light use efficiency of the reflective color display device of this reference example is improved by about 1.5 times compared to the conventional reflective color display device. The color coordinates for white display were (0.311, 0.355).
[Reference Example 2]
Next, another reference example of the color display device according to the present invention will be described. FIG. 7 is a schematic cross-sectional view of the color display device of Reference Example 2. In the following description, descriptions of components having the same or similar configurations and functions as those in Reference Example 1 are omitted.

In the color display device of Reference Example 2, openings 18 are formed in a certain pattern in the reflective layer 10 and a backlight 19 is provided on the back side of the back substrate 2, so-called a reflective / transmissive liquid crystal display device. It is configured as. Thereby, a favorable display can be realized by using the backlight 19 even in a relatively dark environment.
[ Reference Example 3]
Next, another reference example of the color display device according to the present invention will be described. FIG. 8 is a schematic cross-sectional view of the color display device of Reference Example 3. In the following description, description of components having the same or similar configurations and functions as those of Reference Example 1 or 2 will be omitted.

Color display device of Reference Example 3 is not provided with the rear-side polarizing layer 8 such as a substrate 2 in Reference Examples 1 and 2, the phosphor layer 9 has a polarization function. In order to impart a polarizing function to the phosphor layer 9, for example, the trade name Coumarin-6 can be used for green pixels, and the trade name NKX-2197 (Hayashibara Biochemical Laboratories) can be used for red pixels. The reflective layer 10 is composed of a polarizing reflector such as a wire grid or a birefringent resin laminated reflector (for example, trade name D-BEF (manufactured by 3M)). An absorption layer 20 that absorbs light that has passed through 2 is provided.
[ Example ]
Next, a description will be given real施例of a color display device according to the present invention. FIG. 9 is a schematic cross-sectional view of the color display device of the embodiment. FIG. 10 is a schematic explanatory view of a corner cube used in the color display device of the embodiment, where (a) is a schematic plan view and (b) is a schematic perspective view. In the description below, descriptions of components having the same or similar configurations and functions as those of Reference Examples 1 to 3 are omitted.

The color display device according to the embodiment is provided so that the scattering reflection layer 10 converges from the light opening on the viewer side to the bottom on the opposite side of the viewer, and specifically includes a retroreflection plate. Has been. Here, a corner cube array is used as the retroreflector. Thereby, the light extraction efficiency can be improved. In addition, as shown in FIG. 10, the corner cube of a present Example is formed by juxtaposing a plurality of protrusions composed of three surfaces S1, S2, S3 of a regular cube. As the corner cube, a triangular pyramid type can be used.

In the color display device of the embodiment, the phosphor layer 9 is provided near the bottom of the reflective layer 10. Specifically, the phosphor layer 9 is formed near the concave point of the corner cube 10.

  The reflective layer 10 can be formed, for example, by transferring aluminum or the like to an acrylic plate, and the phosphor can be formed by printing or transferring.

Next, the advantages of the embodiment, with reference to FIGS. 11 to 13, will be described below. FIG. 11 is a schematic explanatory diagram when the reflective layer 10 is configured as a plane, and FIG. 12 is a schematic explanatory diagram when the reflective layer 10 is a corner cube. FIG. 13 is a schematic explanatory diagram for comparing the case where the fluorescent material layer 9 is arranged only at the bottom with the corner cube, and the former is shown on the right side and the latter is shown on the left side. In FIGS. 12 and 13, the intermediate layer (liquid crystal layer and the like) is not shown.

  In general, the fluorescent light emission in the phosphor layer 9 isotropically emits in all directions. Therefore, if the fluorescent light emission occurs in a medium such as glass or resin, it is confined inside the medium by total reflection and used as display light for the display device. A lossy component is produced. That is, as shown in FIG. 11, when the reflective layer 10 has a flat structure, the light 22 that travels in the 42 ° cone from the normal direction of the display device among the fluorescence emission is used as the display light. The other light 23 (light outside the 42 ° cone) is confined inside the medium and cannot be used as display light, resulting in a loss component. This loss component reaches about 50% of the total.

  Therefore, as shown in FIG. 12, when the reflective layer 10 has a corner cube structure and the phosphor layer 9 is arranged at the bottom thereof, the fluorescent light emission is directed from the normal direction of the display device into a 42 ° cone. The light 22 is used as display light as it is, and the other light 23 can also be used as display light because the direction in which the light is directed is changed to a direction in which the light is reflected by one surface of the corner cube and is not totally reflected.

  Moreover, the effect which arrange | positions the fluorescent substance layer 9 in the bottom part of the corner cube 10 is demonstrated using FIG. When the phosphor layer 9 is formed on the entire corner cube as shown on the left side of FIG. 13, among the light emitted from the fluorescent light in the phosphor layer 9, the light that goes upward outside the 42 ° cone is totally reflected in the medium. Again, as shown in the right side of FIG. 13, the phosphor layer 9 is formed only near the bottom of the corner cube 10, so that the light 23 outside the 42 ° cone described above is observed on the viewer side by the corner cube 10. Can be used as display light. Further, in the case of a structure like a corner cube, the light 24 that is not directly incident on the phosphor layer 9 is also reflected by the surface constituting the corner cube 10 and can be indirectly incident on the phosphor layer 9. The fluorescent light emission efficiency is not deteriorated in terms of area, and the fluorescent light emission can be efficiently used as display light.

Next, the measurement results of the optical characteristics of this example will be described. Figure 14 is a measurement result of the optical characteristics due to the color display device for measuring apparatus as shown in FIG. 4 in the same manner as in Reference Example 1 embodiment. Thereby, it can be seen that the reflectance is improved by about 1.5 times compared to the case of Reference Example 1.

In addition, although each said reference example and Example had various advantages by the above-mentioned structure, it can change a design suitably in the range which this invention intends.
[ Reference Example 4 ]
Next, another reference example of the color display device according to the present invention will be described. FIG. 15 is a schematic sectional view of Reference Example 4 of the color display device according to the present invention. In the description below, descriptions of components having the same or similar configurations and functions as those of Reference Examples 1 to 3 and the examples are omitted.

In the color display device of Reference Example 4, the phosphor layer 9 is provided so as not to scatter light of components other than the component that converts to a specific color in the incident light. In other words, the phosphor layer 9 is provided in the red pixel so as to convert the blue component light and the green component light of the incident light into red and to transmit the red component light without being scattered. In the green pixel, the blue component of the incident light is converted into green, and the red and green components are transmitted as they are. Further, the blue pixel is provided so as to convert the light of the ultraviolet component of the incident light into blue and to transmit the light of the red component, the green component and the blue component as they are.

  Here, as the phosphor constituting the phosphor layer 9, for example, the red light emitting phosphor is Lumogen F Red 305 (manufactured by BASF), the green light emitting phosphor is Lumogen F Yellow 083 (manufactured by BASF), As the blue light-emitting phosphor, Lumogen F Blue 650 (manufactured by BASF) can be used.

  By using such a phosphor layer 9, the color purity can be improved and a clear display can be realized.

That is, when the fluorescent light emission in the phosphor layer 9 isotropically emits in all directions, if the fluorescent light emission occurs in a medium such as glass or resin, it is confined inside the medium by total reflection, and the display of the display device A component that becomes loss as light is generated. That is, for example, as shown in FIG. 11, when the reflective layer 10 has a flat structure, the light 22 from the normal direction of the display device toward the inside of the 42 ° cone is used as the display light. Other than the light 23 (light outside the 42 ° cone) is confined inside the medium and cannot be used as display light, resulting in a loss component. This loss component reaches about 50% of the total. However, when the phosphor layer 9 uses a phosphor that scatters light, as shown in FIG. 16, the light 23 confined inside the medium by total reflection is scattered again in all directions, and from the normal direction of the display device. Light that is converted into light 221 going into the 42 degree cone also emerges. In this way, when the phosphor layer 9 uses a phosphor that scatters light, a part of about 50% of the light that was a loss component can be reused, and the fluorescence emission can be efficiently performed. It can be used as display light. However, in actuality, as shown in FIG. 16, the thickness of the front substrate 1 and the thickness of the polarizing plate 6 on the viewer side are sufficiently larger than the pixel pitch (the color filter layer 7, the electrode 4, the liquid crystal layer). 3 and the horizontal alignment film 5 etc. are sufficiently thin so that they are ignored here), and the place where the light 23 emitted from the phosphor layer 9 and totally reflected at the interface is scattered again is different from the place where the phosphor layer 9 originally emitted light. . For example, assuming that the thickness of the front substrate 1 is 0.7 mm and the thickness of the polarizing plate 6 on the observer side is 0.3 mm, the light totally reflected at the interface at 42 degrees is as far as 1.8 mm away. If the pixel pitch is 0.1 mm, 18 pixels will be scattered first. In this way, when light is scattered at a place that is significantly different from the place where light was originally emitted, as shown in FIG. 16, the light is scattered at pixels having a color different from that of the emitted light. In FIG. 16, for example, blue is scattered in a red pixel different from the light-emitting pixel, and the red pixel has a display color in which blue is mixed. Thus, when scattering occurs in the phosphor layer, a plurality of colors are displayed. Light mixed in color is observed as display light. Therefore, by adopting the phosphor layer, such as this preferred embodiment, even when incident on the total reflection again different pixel light 23 as shown in FIG. 16, is only reflected by the scattering reflection plate 10 For this reason, the angle is not changed so much and the light is only guided through the refractive index medium without being emitted in the direction of the viewer, and a clear display can be realized.

  In order to evaluate the display color of the display device of this embodiment, each pixel was turned on independently and the entire screen was displayed in a single color. For example, when the entire display is displayed in red, the liquid crystal molecules in the red pixel are aligned in such a state that a voltage is applied so that light is transmitted through the polarizing plate, and the liquid crystal molecules in the other blue or green pixels are aligned. In this state, another voltage is applied so that light does not pass through the polarizing plate. In this way, the entire screen was displayed in a single color, and the chromaticity at that time was measured with a luminance meter BM-5 (manufactured by Topcon).

  Subsequently, the color purity by color mixture was evaluated. As a method for evaluating the color purity, the following method for calculating the NTSC ratio was used. The measured value of the chromaticity measured earlier is plotted on the xy chromaticity diagram, and the area of the completed triangle is obtained in the xy chromaticity diagram. Finally, the ratio of the chromaticity, which is the basis of the NTSC signal, to the area of the triangle was calculated. Here, the reference chromaticity diagram of the NTSC signal is red (x = 0.67, y = 0.33), green (x = 0.21, y = 0.71), blue (x = 0). .14, y = 0.08).

  As a result of the calculation, when the phosphor layer 9 was scattered, the NTSC ratio was 30%. However, when the transparent phosphor layer 9 was used without scattering, an NTSC ratio of 50% was obtained, and high color purity was obtained. It was shown that can be displayed.

  Further, even when the backlight 19 as shown in FIG. 7 is used and reflective / transmissive color display is performed, the phosphor layer 9 is made transparent to eliminate color mixing and display with high color purity. is there. Even when the retroreflective scattering / reflecting layer 10 as shown in FIG. 9 is used, the phosphor layer 9 is made transparent to eliminate color mixing and display with high color purity.

  The present invention can be suitably used for a reflective color display device that uses external light and a reflective / transmissive color display device that also uses a backlight.

It is a schematic sectional drawing of the reference example 1 of the color display apparatus which concerns on this invention. FIG. 10 is a schematic cross-sectional view of a conventional reflective color display device. 6 is a schematic cross-sectional view of a reflective color display device of Reference Example 1. FIG. It is a figure explaining schematic structure of a measuring device. It is a measurement result of the optical characteristic of the reflection type color display apparatus of the reference example 1. It is a measurement result of the optical characteristic of the conventional reflective type color display apparatus. It is a schematic sectional drawing of the reference example 2 of the color display apparatus which concerns on this invention. It is a schematic sectional drawing of the reference example 3 of the color display apparatus which concerns on this invention. It is a schematic sectional drawing of the Example of the color display apparatus which concerns on this invention. It is a schematic explanatory drawing of the corner cube used for the color display apparatus of an Example , (a) is a schematic plan view, (b) is a schematic perspective view. It is a schematic explanatory drawing at the time of comprising a reflective layer with a plane. It is a schematic explanatory drawing at the time of making a reflective layer a corner cube. It is a schematic explanatory drawing for contrasting the case where it arrange | positions to the whole with the case where a fluorescent substance layer is distribute | arranged only to the bottom part in a corner cube. It is a measurement result of the optical characteristic of the color display apparatus of an Example . It is a schematic sectional drawing of the reference example 2 of the color display apparatus which concerns on this invention. It is a schematic explanatory drawing in case a fluorescent substance layer scatters with respect to visible light.

DESCRIPTION OF SYMBOLS 1 Front side substrate 2 Back side substrate 3 Liquid crystal layer 4 Electrode 5 Alignment film 6 Polarizing plate 7 Color filter layer 8 Polarizing layer 9 Phosphor layer 10 Reflecting layer 11 Scattering reflecting layer 12 Polarizing plate 13 Incident light 14 Reflected light 15 Sample 16 Projector 17 Luminance meter 18 Aperture 19 Backlight 20 Absorbing layer 21 Retroreflective layer 22 Light 221 in the 42 degree cone Light 221 converted to go into the 42 degree cone 23 Light outside the 42 degree cone 231 Outside the 42 degree cone Light 24 converted so as to face Light S1, S2, and S3 that do not directly enter the phosphor layer Three surfaces of a regular cube

Claims (7)

A liquid crystal layer is sandwiched between at least the front side substrate on which the color filter means and the transparent electrode are formed and at least the back side substrate on which the transparent electrode, the phosphor layer, and the reflection means are formed. In a color display device provided so as to supply light of a desired color to the viewer side in each pixel by reflecting external light ,
A pixel for supplying a specific color is provided with a phosphor layer that converts light other than the specific color into a specific color among incident light ,
The reflecting means is composed of a retroreflective layer that converges from the light opening on the viewer side to the bottom on the opposite side of the viewer,
The color display device, wherein the phosphor layer is formed only near the bottom of the retroreflective layer . The color display device according to claim 1, wherein the color display device is provided so as to supply red light, green light, and blue light to a viewer side in each pixel by reflecting external light as incident light,
The pixel that supplies red is provided with a phosphor layer that converts blue and green components of incident light into red,
The pixel that supplies green is provided with a phosphor layer that converts blue component light of incident light into green, and color filter means that does not allow red component light to pass through.
A color display device, wherein a pixel supplying blue is provided with color filter means that does not allow light of a red component and a green component to pass through. The color display device according to claim 2 ,
The pixel supplying the red has a smaller area than the pixel supplying the other colors,
The color display device according to claim 1, wherein the pixel supplying green has a smaller area than the pixel supplying blue. A color display device according to any one of claims 1 to 3,
The color display device according to claim 1, wherein the phosphor layer is provided so as to convert light of an ultraviolet component of incident light into a specific color. A color display device according to any one of claims 1 to 4,
The liquid crystal layer is composed of twisted nematic liquid crystal in which the liquid crystal molecular alignment direction is twisted 90 degrees,
Between the liquid crystal layer and the phosphor layer, a color display device, characterized in that polarizing applying means for converting unpolarized light into polarized light is provided. A color display device according to any one of claims 1 to 5,
Before SL phosphor layer, and fluorescence emission for a linearly polarized light, a color display device with respect to linearly polarized light orthogonal to the linearly polarized light to the fluorescent emission, characterized in that is provided so as not fluoresce. A color display device according to any one of claims 1 to 6,
The color display device, wherein the phosphor layer is provided so as not to scatter light of a specific color of incident light.