JP5112230B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device.

The communication speed of portable information devices has been increased, and it is predicted that higher speeds will continue in the future, and that large-capacity image information and moving images with a larger number of frames will be handled by portable information devices. For this reason, display devices that are interfaces are also required to have higher image quality and larger screen than ever.
Display devices used for these portable information devices include various liquid crystal display devices and organic electroluminescence display devices. In particular, in the latter, a color reproduction range is wide, and a display with a wide viewing angle and a high contrast ratio can be obtained. In addition, liquid crystal display devices can be stably supplied in large quantities using existing manufacturing equipment.

In a general liquid crystal display device currently on the market, when a color display is performed on a screen, a combination of a white light source and a color filter is used.
Since this color filter performs color display by selecting a wavelength of light from a white light source and absorbing a part of the light, the color filter has a low transmittance and the light source light utilization efficiency is low. In particular, when an attempt is made to obtain a wide color reproduction range equivalent to that of an organic electroluminescence display device by means of a liquid crystal display device, the color filter has a much lower transmittance and the utilization efficiency of light source light is significantly reduced.

Conventionally, a phosphor and a scatterer are placed in front of a liquid crystal display device, a part of the blue light of the polarization collimated light source is used for blue display, and a part of that color is converted to red and green with the phosphor for display. The method of performing is disclosed (for example, refer to Patent Document 1).
Since Patent Document 1 directly uses fluorescence, it has a feature that the color reproduction range is as wide as that of an organic electroluminescence display device. Moreover, since this patent document 1 does not use light absorption, it has the characteristic that the utilization efficiency of light source light is high compared with the general liquid crystal display device marketed now.
JP 2000-131683 A

In general, fluorescence has a property of extending isotropically from a light emission region. In the case of the liquid crystal display device using this fluorescence, the light emitted in front of the front plate out of the isotropically spreading light is only the emission angle component equal to or less than the total reflection angle on the front plate surface.
Assuming that the fluorescence spreads in a spherical shape, the fluorescence generated in the plane including the front plate has only a component in the cone whose apex angle is twice the total reflection angle on the front plate surface. To exit.

  The remaining components other than the components in the cone are emitted from the rear of the front plate or are repeatedly subjected to multiple reflection in the plane of the front plate. Therefore, even if the light source light can be converted into fluorescence with high efficiency without being absorbed, most of the fluorescence converted with high efficiency cannot be taken forward and used for display.

Further, when the phosphor is placed on the front surface of the optical shutter, external light is directly incident on the phosphor. If the wavelength range of external light includes the excitation wavelength range of fluorescence, fluorescence is generated by external light. External light components not in the fluorescence excitation wavelength region are also scattered by the phosphor. Since these lights do not receive control reflecting the image signal by the optical shutter, they become unnecessary reflections and degrade the image.
Specifically, the contrast ratio and the color reproduction range are reduced. Portable information devices may be used indoors as well as outdoors, but unnecessary reflections such as fluorescence generated by external light in the fluorescence excitation wavelength range and scattering of external light components not in the fluorescence excitation wavelength range. Is particularly generated in a bright environment, and thus the image is particularly deteriorated when used outdoors.

  An object of the present invention is to provide a liquid crystal display device capable of improving the light extraction rate from the front plate when a phosphor is used for the front plate and preventing unnecessary reflection caused by external light. To do.

In order to solve the above problems, the present invention provides:
Constructed by laminating a collimating blue light source, an optical shutter and a front plate,
The front plate includes a red phosphor layer that converts blue light source light into red, a green phosphor layer that converts blue light source light into green, and a light scattering layer that scatters blue light source light,
The optical shutter has a plurality of independently controlled pixels,
A phosphor layer or a light scattering layer is provided on the front plate in a one-to-one correspondence with the pixels of the optical shutter,
In a liquid crystal display device that condenses light source light on a phosphor layer or a light scattering layer through pixels on the optical shutter,
A light extraction structure for directing scattered light generated in the phosphor layer and the light scattering layer to the user side on the front plate is provided,
The light extraction structure is
It consists of a first reflector and a second reflector, and the first reflector is distributed on the slope except for the vicinity of the apex of the conical structure,
The conical structure is
It is arranged with the vertex facing the light source side,
The second reflector is
Arranged on the bottom side of the conical structure;
On the side close to the light source of the second reflector,
The light scattering layer or the fluorescent layer is laminated,
The light source light is condensed and applied to the light scattering layer or the fluorescent layer through the vicinity of the apex of the cone-shaped structure using a microlens array .

ADVANTAGE OF THE INVENTION According to this invention, the light extraction efficiency of the fluorescence in the display element which has arrange | positioned the fluorescent substance with high utilization efficiency of light source light to a front plate can be improved, and a highly efficient display element can be obtained.
Moreover, according to this invention, the unnecessary reflection by a fluorescent substance can be reduced and favorable outdoor visibility can be acquired.

<< First Embodiment >>
Hereinafter, a first embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

  FIG. 1 is a cross-sectional view including three pixels of a display device, and FIG. 2 is a diagram showing a light distribution, pixel electrode, and microlens array extracted from FIG. .

FIG. 1 schematically shows a cross section including three pixels of a display device according to the present invention.
In FIG. 1, the display device is mainly composed of a front plate, an optical shutter, a collimated light source, and a light collecting means. In this display device, a front plate, an optical shutter, a collimated light source, and a condensing unit are stacked in the order of the front plate, the optical shutter, and the collimated light source.

FIG. 2 shows the light scatterer, the pixel electrode, and the microlens array MLA in FIG.
As shown in FIG. 2, the front plate has a plurality of light scatterers that generate diffused light in a matrix. The light scatterer includes a red phosphor RF that converts blue light into red, a green phosphor GF that converts blue light into green, and a blue light scatterer BD that scatters blue collimated light. Yes.

First, the outline of the operation principle of the display device according to the present invention will be described.
As shown in FIG. 2, the optical shutter includes a plurality of pixels that can be controlled independently according to an image signal in a matrix.
The collimated light source BLS has one or a plurality of blue light emitting diodes, and has a light guide for converting light from the light emitting diodes into planar collimated light.
The arrow in FIG. 1 indicates the optical path after exiting the collimated light source. The blue light emitted from the collimated light source is condensed on the light scatterer on the front plate by the condensing means. It passes through and undergoes intensity modulation corresponding to the image signal.
As shown in the perspective view of FIG. 2, each pixel and the light scatterer have a one-to-one correspondence, and the light source light that has passed through one pixel is incident only on the corresponding light scatterer. Scattered light generated in the above is also subjected to intensity modulation corresponding to the image signal.

  The blue light emitted from the collimated light source BLS passes through the optical shutter exclusively in the normal direction or in a fixed direction close thereto. Therefore, the optical shutter is not required to have a wide viewing angle characteristic, and is required to exhibit a high contrast ratio and gradation display characteristic only in the direction in which blue light passes. The optical shutter only needs to satisfy a high contrast ratio and gradation display characteristics only in the wavelength range of blue light, not in the entire visible wavelength range.

Next, details of each element constituting the present invention will be described.
In this embodiment, a liquid crystal display element is used for the optical shutter. The liquid crystal display element mainly includes a first substrate SU1, a second substrate SU2, and a liquid crystal layer LC, and the first substrate SU1 and the second substrate SU2 sandwich the liquid crystal layer LC. The first substrate SU1 is made of borosilicate glass having a thickness of about 0.4 mm, and the first alignment film AL1 and the common electrode are sequentially stacked from the side close to the liquid crystal layer LC. The first alignment film AL1 is a polyimide organic polymer film, and is a horizontal alignment film that gives a pretilt angle of about 3 degrees to the adjacent liquid crystal layer LC.
The common electrode is ITO (Indium Tin Oxide) excellent in transparency and conductivity, and the layer thickness is 80 nm. The common electrode is distributed so as to cover all the pixels in the optical shutter.

The second substrate SU2 is made of borosilicate glass like the first substrate SU1, and in order from the side close to the liquid crystal layer LC, the second alignment film AL2, the pixel electrode, the first insulating film, the thin film transistor, A signal line SL, a second insulating film, a scanning line GL, and a common line are provided.
The second alignment film AL2 is a horizontal alignment film similar to the first alignment film AL1. The pixel electrode is ITO having a layer thickness of 80 nm, like the common electrode. The first insulating film insulates the pixel electrode from the signal wiring SL, and the second insulating film insulates the signal wiring SL from the scanning wiring GL and the common wiring, both of which are 500 nm thick silicon nitride It is made of (SiN).
The common wiring runs in parallel with the scanning wiring GL and is in the same layer as the scanning wiring GL. The common wiring has a portion overlapping with the pixel electrode when observed from the normal direction, and forms a storage capacitor.

The signal line SL and the scanning line GL intersect each other, and have a thin film transistor in the vicinity of the intersecting portion, corresponding to the pixel electrode on a one-to-one basis. A potential corresponding to an image signal is applied to the pixel electrode from the signal wiring SL through the thin film transistor and the contact hole, and the thin film transistor operation is controlled by the scanning signal of the scanning wiring GL.
The channel portion of the thin film transistor is made of an amorphous silicon layer, and the channel portion may be formed of a polysilicon layer having higher mobility.
As shown in FIG. 2, the planar shape of each pixel is a substantially square shape, and the pixel array is a staggered array in which adjacent pixel columns are shifted by half a pixel.

The liquid crystal layer LC is a mixture of a liquid crystal material and a chiral material, and the liquid crystal material has a positive dielectric anisotropy and exhibits a nematic phase in a wide temperature range including room temperature. Further, the chiral material is an optical rotatory substance having an asymmetric center, and stabilizes the twisted alignment of the liquid crystal layer LC.
The function of the high resistance and the storage capacitance that the liquid crystal material exhibits prevents a voltage drop of the liquid crystal layer LC during the holding period in which the thin film transistor is turned off. After the first alignment film AL1 and the second alignment film AL2 are subjected to the alignment process by the rubbing method, the first substrate SU1 and the second substrate SU2 are assembled, and the gap between them is on the first substrate SU1 side. It is maintained uniformly by the arranged post spacers having a substantially cylindrical shape. A mixture of a liquid crystal material and a chiral material is vacuum-sealed in the gap to form a twisted liquid crystal layer LC having a twist angle of 90 degrees.

A first polarizing plate PL1 and a second polarizing plate PL2 are arranged outside the first substrate SU1 and the second substrate SU2, and the first polarizing plate PL1 and the second polarizing plate PL2 are iodine dyes. The natural light is converted into linearly polarized light with a high degree of polarization due to its dichroism. The first polarizing plate PL1 and the second polarizing plate PL2 are arranged so that their absorption axes are orthogonal to each other when observed from the plane normal direction, and the absorption axes of the first polarizing plate PL1 are close to each other. The alignment film AL1 is parallel to the liquid crystal alignment direction.
Thus, a twisted nematic liquid crystal display element was obtained. The twisted nematic liquid crystal display element exhibits normally-open type transmittance-voltage characteristics in which the transmittance is maximized when no voltage is applied, and the transmittance decreases as the applied voltage increases.

The collimated light source BLS is mainly composed of a light emitting diode LS, a light guide plate LG, and a prism sheet PS. The light emitting diode LS is a gallium nitride-based blue light emitting diode BLS, and exhibits a light emission spectrum in the form of a bright line having a half width of about 30 to 40 nm with a wavelength of 460 nm as the center.
The light guide plate LG is made of a polycarbonate organic polymer having high transparency and weather resistance, and includes a light emitting diode LS at one place on the side surface of the light guide plate LG. By limiting the position of the light emitting diode LS to one place on the side surface, if the light emitting diode LS is regarded as a point light source, the direction and angle of the light emitting diode LS light reaching an arbitrary point at the bottom of the light guide plate LG is uniquely determined. .

Accordingly, if the angle of the bottom of the light guide plate LG at each point is determined so that the interface between the light guide plate LG and the air satisfies the total reflection condition, the light emitting diode LS light propagating through the light guide plate LG can be guided with high efficiency. It can be taken out of the light plate LG. As a result, the structure of the bottom of the light guide plate LG is a concentric groove structure centered on the light emitting diode.
At this time, the traveling direction of the light coming out of the surface of the light guide plate LG is not parallel to the normal direction of the light guide plate LG, and its orientation is distributed radially around the light emitting diode LS. In order to direct the direction in the normal direction, the prism sheet PS is disposed on the light guide with the inclined surface facing the light guide.

The grooves of the prism sheet PS are also concentric with the light emitting diode as the center. When the light guide is observed from the normal direction of the light emitting surface, it is roughly rectangular. However, the position of the light emitting diode LS on the side surface of the light guide plate LG may be the center of one side of the rectangle or one of the vertices. good.
The collimated light source BLS having such a configuration has extremely high collimating properties. When the angular distribution of the light is evaluated, the half-value width is 5 degrees or less depending on the orientation. When this is observed directly from the normal direction, the brightness observed by the left and right eyes is significantly different, and when observed directly from the oblique direction, the luminance uniformity of the light emitting surface is significantly reduced, which is not practical. When used in combination with a light scatterer, these disadvantages are eliminated and it becomes practical.

The front plate is mainly composed of the third substrate SU3, a light extraction structure provided on the surface, and a light scatterer.
The light extraction structure is an aluminum film having a high reflectance, and has a reflective surface inclined with respect to the plane of the third substrate SU3. When viewed three-dimensionally, the reflecting surface of the light extraction structure forms a part of a cone and is distributed on the slope except for the vicinity of the apex of the cone.
The vicinity of the apex of the cone is transparent because the light extraction structure is not distributed, that is, a light incident part for collimated backlight light to enter the inside of the light extraction structure. The apex of the cone formed by the light extraction structure faces the optical shutter side.

A light scatterer is provided inside the light extraction structure, that is, inside the conical structure. The light scatterer is composed of a red phosphor RF, a green phosphor GF, and a blue light scatterer BD. The planar distribution of this light scatterer is staggered like the pixels of the optical shutter.
The red phosphor RF and the green phosphor GF are transparent resins in which fluorescent materials that absorb in the emission wavelength region of the blue light emitting diode BLS and emit fluorescence of each color are dispersed, and the blue light scatterer BD is made of a high material such as barium titanate. A transparent resin in which refractive index particles are dispersed.

The condensing means is a microlens array MLA, which is formed on the second polarizing plate PL2 of the optical shutter. In the microlens array MLA, a photopolymerizable low-molecular solution is applied onto the second polarizing plate PL2 by a printing method.
At the start of coating, the positions of the microlens ML and the pixel are aligned so that the light passing through the microlens ML passes through the corresponding pixel. The photopolymerizable low molecular weight solution forms a meniscus at the time of coating, and its shape is determined by the surface tension and viscosity of the solution, and further by the surface tension of the second polarizing plate PL2. By optimizing these factors, a meniscus shape suitable for condensing collimated light from the light source at the incident portion is obtained.

This is irradiated with ultraviolet rays to polymerize the photopolymerizable low molecule and solidify by removing the solution. Each microlens ML has a circular planar shape and a convex sectional shape, and the planar distribution of the microlens array MLA is staggered.
In other words, the microlens array MLA, the light shutter pixels, and the light scatterers on the front plate are all arranged in a staggered manner, and one set corresponds to each other as shown in FIG. is doing. The collimated light source BLS light that has passed through an arbitrary microlens passes through a pixel paired with the light beam while narrowing the cross-sectional area of the light beam, and further converges on the light incident part of the light scatterer paired therewith. .

FIG. 3 shows an optical path of fluorescence generated inside the phosphor.
The phosphor does not float in the air, but is embedded in some layer that exhibits a higher refractive index than the air layer when used in a display device.
The red phosphor RF and the green phosphor GF absorb the light of the blue light emitting diode BLS and emit red and green fluorescence. At that time, the fluorescence is uniformly emitted in all directions. Now, assuming that the refractive index of each phosphor is 1.5, the total reflection angle TRA at the air interface is about 42 degrees.
As shown in FIG. 3A, the component whose polar angle is equal to or smaller than the total reflection angle TRA becomes the front emission component FL or the rear emission component RL, and goes to the outside of the front plate, but other components propagate in the layer. It becomes a component TL and multiple reflections occur in the layer.

FIG. 3B is a three-dimensional view of the cross-sectional view shown in FIG. In FIG. 3B, the arrow indicating the fluorescence optical path is omitted. FIG. 3B shows that the front emission component FL and the rear emission component RL are distributed in a cone having an apex angle of 84 degrees, and the other intra-layer propagation components TL occupy the majority.
In this embodiment, by arranging the light extraction structure around each phosphor, the in-layer propagation component TL can be reflected by the inclined reflection surface and directed to the outside of the front plate, and the light utilization efficiency Can be greatly improved. Further, the blue light diffuser BD isotropically scatters the light source light with high collimation property, reflects the light with the light extraction structure, and directs it toward the outside of the front plate. By optimizing the scattering characteristics, the viewing angle characteristics similar to those of the red phosphor RF and the green phosphor GF can be obtained.

The red phosphor RF and the green phosphor GF convert blue light, which is excitation light, into fluorescence. However, if some of the blue light passes through without being absorbed, the display color will be bluish and the color reproduction range will be reduced.
When the concentration of the phosphor dispersed in the red phosphor RF and the green phosphor GF is sufficiently small, the absorption rate of the blue light that is the excitation light is expressed by the Lambert-Beer law, and the intensity of the blue light is Is not dependent. The actual phosphor concentration is high, exceeding the range where Lambert-Beer's law is applied.
In this case, the blue light is subjected to reabsorption by the phosphor and excitation movement between excited molecules, and the transmission component is also scattered by the phosphor particles and the resin interface. Therefore, the absorption rate is obtained by some sequential analysis method and cannot be obtained analytically. The depth at which blue light penetrates into the phosphor is called the penetration length. Since the penetration length increases as the luminance of blue light increases, it is sufficient that the layer thickness of the phosphor is thicker than the penetration length when the blue light has the maximum luminance.
At least, if the phosphor particles are packed in an amount that completely absorbs blue light when it has the maximum luminance, it can be completely absorbed even when the blue light has a lower intensity. The amount can be determined experimentally.
Since the blue light scatterer, the red phosphor, and the green phosphor are present away from the light emitting diode, the absorptance is not lowered due to the heat generation.

Since the penetration length increases as the luminance of blue light increases, the total amount of phosphors present within the blue light reachable range also increases. Therefore, the fluorescence intensity is not proportional to the blue light luminance, and a nonlinear effect that increases more rapidly as the fluorescence intensity increases can be obtained.
Due to this nonlinear effect, the contrast ratio exhibited by the fluorescence becomes larger than the contrast ratio of the optical shutter. By utilizing this, it becomes possible to display with a high contrast ratio exceeding that of a liquid crystal display element which is an optical shutter.
Alternatively, a sufficient contrast ratio can be displayed by using an optical shutter having a lower contrast ratio. For example, a polarizing plate having a lower polarization degree can be used. In the polarizing plate containing the above-mentioned iodine pigment, the transmittance tends to decrease as the degree of polarization increases, and the degree of polarization and transmittance are in a trade-off relationship.
By utilizing the non-linearity of the fluorescence emission, a sufficient contrast ratio can be obtained even with a polarizing plate having a lower degree of polarization. At this time, the transmittance of the liquid crystal display element is improved, so that a display with higher luminance can be obtained.

The light extraction structure and the light scatterer may be formed on the surface of the third substrate SU3 that is close to the optical shutter, or may be formed on the surface of the third substrate SU3 that is away from the optical shutter. Further, it may be formed on the surface of the third substrate which is opposite to the optical shutter.
In each case, the light extraction structure, the method of forming the phosphor and the light scatterer will be described below.
FIG. 20 is a diagram showing a procedure for forming a light extraction structure, a phosphor, and a light scatterer on a surface of the third substrate close to the optical shutter.
First, a resist in which each phosphor and scatterer is dispersed is sequentially formed and patterned by a photolithograph so that the planar shape becomes a circle. FIG. 20A shows a stage in which only the red phosphor layer is formed.
When processing is performed so that the end shape is inclined during development in the photolithographic process, each phosphor and scatterer has a trapezoidal rotary body structure, and is arranged so that the planar distribution is in a staggered arrangement. .

FIG. 20B shows a stage where a red phosphor layer, a green phosphor layer, and a light scattering layer are formed.
An aluminum film is formed thereon, and the aluminum film is removed from the upper end of the rotating body structure by photolithography. As a result, a reflection film distributed on the inclined surface excluding the vicinity of the apex of the cone is formed, and as shown in FIG. 20C, a light extraction structure having each phosphor and scatterer inside and a light incident portion thereof are formed. . In this case, since the light extraction structure and the light scatterer are located in the vicinity of the optical shutter, a transparent planarization film OC is applied on the aluminum film in order to improve the adhesion to the optical shutter, and FIG. As shown in d), the unevenness due to the light extraction structure is flattened.

When each pixel of the optical shutter is approximately square, the planar structure of the light extraction structure is a circle, and the planar shape of the microlens ML that is a condensing means is a circle, these are arranged most closely by arranging them in a staggered arrangement. Can be arranged. Assuming that the intensity distribution of the collimated light source BLS is uniform in the plane, the proportion of the collimated light source BLS light that can be condensed by the microlens ML can also be increased. For this reason, there exists an advantage that the collimated light source BLS can be utilized more effectively.
Further, the collimated light source BLS light that does not enter the microlens ML may become unnecessary light because the pixels that enter the optical shutter cannot be specified. By disposing the black matrix in the same layer as the microlens ML and where the microlens ML does not exist, the collimated light source BLS light that does not enter the microlens ML can be removed.
Alternatively, unnecessary light can be removed by arranging the black matrix in a layer near the pixel of the optical shutter. Specifically, a black matrix may be disposed between the first substrate SU1 and the common electrode. In this case, when the first substrate SU1 and the second substrate SU2 are combined, it is necessary to align them.

In the case where the light extraction structure and the light scatterer are formed on the surface of the third substrate SU3 opposite to the optical shutter, first, a transparent transparent film is formed, and the structure shown in FIG. As shown, this is patterned to form holes with a circular planar shape arranged in a staggered arrangement. When the end shape is processed to be a slope during development in the photolithographic process, the circular hole becomes a concave structure in which a trapezoidal rotating body structure is inverted. An aluminum film is formed thereon and patterned to remove the aluminum film from the bottom of the concave structure.
As a result, a reflection film distributed on the slope except for the vicinity of the apex of the cone is formed, and a light extraction structure and a light incident portion are obtained as shown in FIG.
Next, a resist in which each phosphor and scatterer are dispersed is sequentially formed, and is left inside each concave structure by photolithography as shown in FIG. 21C so as to fill the inside of the concave structure. . In this case, since the light extraction structure and the light scatterer are located on the uppermost surface, the user may directly touch the light extraction structure and the light scatterer when holding the display device of the present invention.
Therefore, as shown in FIG. 21 (d), the light extraction structure and the light scatterer are covered with a hard coat layer to ensure the surface hardness, and the display surface is not damaged even when subjected to a load such as mechanical friction. Like that.

In FIGS. 20 and 21, photolithography is used for patterning of each layer, and slope formation on the side surfaces of the phosphor layer and the light scattering layer is realized by optimizing the development conditions of the photolithography.
In addition, slopes can be formed on the side surfaces of each layer using embossing.
A stamping die must be prepared separately for embossing, but it has the advantage that the slope angle reproducibility is relatively good regardless of the processing conditions. For example, even if embossing is performed on the transparent film in FIG. 21A, a concave structure in which a trapezoidal rotating body structure is inverted is obtained.

The front plate, the optical shutter, and the collimated light source BLS are stacked to form the display device of the present invention. In particular, the front plate and the optical shutter are fixed after alignment. For alignment, alignment marks are printed on the front plate and the peripheral part of the optical shutter, and are observed so that the alignment marks of the two match when observed from the normal direction.
In order to fix the both, a heat-polymerizable or photopolymerizable resin is applied to at least one of the front plate or the optical shutter, and after both are superposed, they are heated or irradiated with light and adhered.

  The alignment mark on the front plate may be formed in the same layer as the wiring, for example. The alignment mark of the optical shutter may be formed in the same layer as the reflective layer RE, for example. Other than this, any layer that is opaque and can be finely processed can be used for the alignment mark. The first polarizing plate PL1 and the second polarizing plate PL2 of the optical shutter are arranged so that their absorption axes are orthogonal to each other, and absorb light almost completely in the normal direction, but at least on the alignment mark. If one is not distributed, it will not be an obstacle to alignment.

When the display state of the display device created as described above was observed, a display having a wide color reproduction range and excellent viewing angle characteristics was confirmed.
As described above, a high-efficiency display device using light conversion by a phosphor is obtained.

<< Second Embodiment >>
Hereinafter, a second embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

In Example 1, a phosphor layer, a light scattering layer, a light extraction structure, and the like were formed on the front plate. However, in this example, these were formed directly on the optical shutter without using the front plate.
FIG. 22 schematically shows a cross section including three pixels of the display device according to the present invention.

In FIG. 21, a phosphor layer, a light scattering layer, a light extraction structure, and the like are formed on the surface of the third substrate that is opposite to the optical shutter. In this embodiment, after assembling a liquid crystal display element as an optical shutter, a phosphor layer, a light scattering layer, a light extraction structure, etc. are formed on the first polarizing plate in the same manner as shown in FIG. did.
Even in this configuration, the light extraction efficiency of fluorescence is improved, and a highly efficient display element can be obtained. In addition, in this embodiment, a phosphor layer, a light scattering layer, a light extraction structure, and the like are formed on the optical shutter without using the front plate, so that the thickness and weight can be reduced compared to the first embodiment. did it.

<< Third Embodiment >>
Hereinafter, a third embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

In Examples 1 and 2, a polarizing plate containing an iodine dye was used as the first polarizing plate PL1, and this was laminated on the outside of the first substrate SU1.
The iodine dye is dispersed in the polyvinyl alcohol polymer and has a triacetyl cellulose film on the upper and lower sides to ensure weather resistance. Since it has such a laminated structure, the polarizing plate containing an iodine dye has a characteristic that the film thickness is relatively thick.

In the present embodiment, the first polarizing plate PL1 is formed inside the first substrate SU1.
In Examples 1 and 2, since the first polarizing plate PL1 is pasted after the liquid crystal panel that is an optical shutter is completed, the first polarizing plate PL1 does not receive a thermal history when the liquid crystal panel is formed.
When the first polarizing plate PL1 is formed on the inner side of the first substrate SU1 as in the present embodiment, the first polarizing plate PL1 receives a thermal history, so that the first polarizing plate PL1 has a heat resistance. Is required.
For this reason, in this embodiment, a material different from those in Embodiments 1 and 2 is used for the first polarizing plate PL1.

The chromonic liquid crystal is a kind of lyotropic liquid crystal that becomes liquid crystal in an aqueous solution state and exhibits light absorption as apparent from the fact that it is used as a pigment. The molecular shape is a plate shape or a disk shape, and these form a stacked columnar structure. Due to this columnar structure, the light absorption of the chromonic liquid crystal exhibits anisotropy and has an absorption axis in the vertical direction of the columnar structure.
If the chromonic liquid crystal is applied while applying a shear stress, a film can be formed while maintaining the columnar structure, and a columnar structure parallel to the shear stress and parallel to the film plane is formed.

In this example, chromonic liquid crystal was used for the first polarizing plate.
By forming so that the shear stress is perpendicular to the absorption axis direction of the first polarizing plate PL1 of Examples 1 and 2, in the same direction as the first polarizing plate PL1 of Examples 1 and 2. The absorption axis can be turned.
Specifically, by applying it in a film form while extruding it through a nozzle of a printing press, it is possible to form a film simultaneously with the application of shear stress.
The dichroic ratio of a polarizing plate using chromonic liquid crystal depends on the alignment process, and the dichroic ratio may be lower than that of a polarizing plate containing an iodine dye. Even in such a case, it is possible to compensate for the decrease in contrast ratio due to the nonlinearity exhibited by fluorescence.

FIG. 23 schematically shows a cross section including three pixels of the display device according to the present invention.
In FIG. 23, the front plate is not used as in the second embodiment, and a phosphor layer, a light scattering layer, a light extraction structure, and the like are formed on the optical shutter.
In addition to excluding the front plate, the first polarizing plate was made of a chromonic liquid crystal having a thinner film thickness, so that the thickness and weight could be further reduced as compared with Example 2.

<< Fourth Embodiment >>
Hereinafter, a fourth embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

In this embodiment, an attempt is made to control the polar angle distribution of the emitted light.
FIG. 4 schematically shows a cross section including three pixels of the display device according to the present invention.
In the present embodiment, the blue light scatterer BD, the red phosphor RF, and the green phosphor GF are distributed only in the vicinity of the light incident part inside the light extraction structure.

The optical path inside the light extraction structure at this time is shown in FIG.
In FIG. 5, a green phosphor GF is shown as a representative of three types of light scatterers.
Since the scattered light is emitted only in the vicinity of the light incident portion, the scattered light is distributed in a polar angle range equal to or less than the apex angle of the cone formed by the light extraction structure. That is, the component that has exited the phosphor below the apex angle of the cone does not enter the reflective layer RE and travels forward.
In addition, the component that has emitted the phosphor at a vertex angle greater than or equal to the cone angle is incident on the reflection layer RE and reflected. As a result, the polar angle of the path becomes less than the vertex angle of the cone. For this reason, the reflection angle of the reflection plate of the light extraction structure is set to be equal to or smaller than the total reflection angle TRA at the air interface, and further, a component directed to the optical shutter side through the light incident portion is reflected and extracted by an interference filter described later, thereby extracting light. All of the scattered light generated inside the structure can be directed to the outside of the front plate.

  In addition, since the display device of this embodiment uses scattered light due to fluorescence, gradation viewing characteristics in a wide gradation can be obtained without gradation inversion in the viewing angle direction. If the viewing angle characteristics of the blue light scatterer BD, the red phosphor RF, and the green phosphor GF are the same, the same color tone as the normal direction can be obtained in the viewing angle direction.

When the reflection plate inclination angle of the light extraction structure is the total reflection angle TRA at the air interface, the scattered light is distributed in all solid angles outside the front plate.
If the polar angle is defined with the normal direction set to 0 degree, the display element can be observed from the side at the polar angle of 90 degrees, so that the display surface itself cannot be observed, but the gradation is in the entire angle range where the display surface can be observed. Good display without inversion or hue change can be obtained.

FIG. 5 shows an example of control of the polar angle distribution of diffused light in the present embodiment.
FIG. 5A is an example in which the reflection plate inclination angle of the light extraction structure is set to the total reflection angle TRA at the air interface, and the light emitted from the front plate is distributed within a range of ± 90 degrees as a polar angle. To do.
Further, as shown in FIG. 5 (b), when the reflection plate inclination angle of the light extraction structure is made smaller than the total reflection angle TRA at the air interface, the scattered light is centered in the normal direction outside the front plate. Distributed within a narrow solid angle.

  As described above, it is not practical because the display surface itself is difficult to observe at a polar angle of 90 degrees and its vicinity. In addition, a wide viewing angle range is unnecessary in applications that are limited to personal use, and in these applications, if the reflector tilt angle of the light extraction structure is reduced and the amount of light per unit solid angle is increased, A bright display can be obtained. Specifically, the resist in which each phosphor and scatterer are dispersed is patterned by photolithography, but the slope of the end shape is adjusted by adjusting the etching rate by changing the concentration of the developing solution during development in the photolithography process. Change the angle.

<< Fifth Embodiment >>
Hereinafter, a fifth embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

  In Example 1, the micro lens ML is formed on the second polarizing plate PL2. However, since the second polarizing plate PL2 has a large coefficient of thermal expansion, the second polarizing plate PL2 is subjected to a large temperature change. After expansion and contraction, it returns to its original size. At this time, if the second polarizing plate PL2 does not completely return to its original shape, the position of the pixel forming a pair with the microlens ML may be shifted from each other.

In the present embodiment, the microlens ML is formed at a position different from that in the first embodiment.
As shown in FIG. 6, the microlens ML may be formed on the second substrate SU2. Since the second substrate SU2 made of borosilicate glass has a low coefficient of thermal expansion, there is no displacement due to the thermal history as described above.
In this case, the second polarizing plate PL2 may be attached so as to contact the apex of the convex portion of the microlens ML, or may be attached to the prism sheet PS of the collimated light source BLS as shown in FIG.
As described above, a display device can be obtained in which the display characteristics do not change even when there is a temperature variation such as heating and cooling.

In addition, the microlens ML may be formed on the first polarizing plate PL1 as shown in FIG.
When the light source light is not perfect collimated light but has an angular distribution, the closer the positions of the microlens ML and the light scatterer are, the more light source light can be condensed by the light incident part. Actually, the collimated light source BLS actually obtained is not a perfect collimated light source BLS and often has some angle dependency.
In the configuration shown in FIG. 7, since the positions of the microlens and the light scatterer are closer to each other, the collimated light source BLS light can be condensed on the light incident portion even when the collimated light source BLS has a slightly low collimation property. In this case, the optical shutter and the front plate are not completely brought into close contact with each other, and are fixed so as to be in contact only at the vertex of the convex portion of the microlens ML as shown in FIG. Alternatively, a separate mold may be prepared and both may be fixed.

Furthermore, if the microlens is formed on the first substrate SU1 as shown in FIG. 8, the position shift due to the thermal history does not occur as described above.
In this case, the first polarizing plate PL1 may be attached so as to contact the apex of the convex portion of the microlens ML.

As shown in FIG. 9, the microlens ML may be formed on the surface of the front plate close to the optical shutter. Since the positions of the microlens ML and the light scatterer are closer to each other, the collimated light source BLS light can be easily condensed on the light incident portion.
In this case, the optical shutter and the front plate are not completely brought into close contact with each other, and are fixed so as to contact only at the convex vertex of the microlens ML as shown in FIG.
Alternatively, a separate metal frame may be prepared and both may be fixed.

<< Sixth Embodiment >>
Hereinafter, a sixth embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

Unnecessary light that may be generated in the display device according to the present embodiment is classified and shown in FIG.
Among these, FIG. 10A is a diagram in which unnecessary light generated due to the light of the collimated light source BLS is classified.
In the present embodiment, attention is focused on the third unnecessary light component UL3. Since the scattered light generated by the light scatterer spreads isotropically, a part of the scattered light may be directed to the optical shutter side. If this is reflected by one of the layers of the optical shutter, re-enters another light scattering layer, and exits in front of the front plate, it becomes the third unnecessary light component UL3, which may reduce the display image quality.

FIG. 11 is a cross-sectional view including three pixels of the display device of this embodiment.
In FIG. 11, in order to reduce the third unnecessary light component UL3, a blue color filter BL is disposed between the light scattering layer of the front plate and the pixels of the optical shutter in the display device of Example 1. The blue color filter BL allows the collimated light source BLS light to pass through, but absorbs the fluorescence of the red phosphor and the green phosphor. For this reason, it is possible to prevent deterioration in image quality due to fluorescence of at least the red phosphor and the green phosphor.

In addition to this, an interference filter may be disposed between the light scattering layer of the front plate and the pixels of the optical shutter. The interference filter is a laminate of at least two types of thin films having different refractive indexes, and exhibits a property of reflecting light in a specific wavelength range. The interference filter may be formed by vacuum deposition of an inorganic material, but can be more simply formed by applying an organic polymer film.
If the wavelength range of the reflector is set so that the blue light of the collimated light source BLS passes and reflects the fluorescence of the red phosphor RF and the green phosphor GF, the red fluorescence is the same as when the blue color filter BL is arranged. It is possible to prevent deterioration in image quality due to fluorescence of the body RF and the green phosphor GF.
Further, if the interference filter is arranged close to the light extraction structure, the fluorescent component directed to the optical shutter side is reflected to the emission side, and this can be used for display. Although the fluorescent component toward the optical shutter side is less than the component directed to the front of the front plate by the light extraction structure, the light utilization efficiency can be further improved by utilizing this for display.

<< Seventh Embodiment >>
Hereinafter, a seventh embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

In FIG. 10B, unnecessary light that may be generated by incident light from the outside is classified and shown. That is, the unnecessary light in FIG. 10B is unnecessary light that does not occur in a relatively dark environment such as a dark room or indoors, but may be generated in a bright environment such as outdoors.
In the present embodiment, focusing on the fifth unnecessary light component UL5 among these, an attempt is made to improve the outdoor visibility of the display element of the present invention.

  In the display element of the present embodiment, when light having the same wavelength region as that of the blue light emitting diode BLS used for the excitation light of the red phosphor RF and the green phosphor GF is incident on these from the outside, the red phosphor RF and the green phosphor GF. May absorb this and emit fluorescence. Such fluorescence becomes the fifth unnecessary light because it is not controlled by the image signal, and if it is observed by the user, the contrast ratio of the display is lowered and the color purity is lowered. It has become.

FIG. 12 is a cross-sectional view including three pixels of the display device of this example.
In FIG. 12, in the display device of Example 1, a yellow color filter YE is disposed in front of the red phosphor RF and the green phosphor GF.
The yellow color filter YE absorbs blue light and passes red and green light. Blue light is prevented from entering the red phosphor RF and the green phosphor GF from the outside, and the red and green fluorescence traveling to the outside is allowed to pass with a high transmittance. Thereby, the red phosphor RF and the green phosphor GF do not emit fluorescence by external light excitation, and outdoor visibility is improved.

<< Eighth Embodiment >>
Hereinafter, an eighth embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

  In this example, paying attention to the sixth unnecessary light component UL6, an attempt was made to improve the outdoor visibility of the display element of this example. That is, in Example 1, there is a possibility that light incident from the outside reaches the reflection layer RE and is reflected by the reflection layer RE. If this is observed by the user, a reduction in display contrast ratio, a decrease in color purity, and the like occur, which contributes to a decrease in outdoor visibility.

FIG. 13 is a cross-sectional view including three pixels of the display device of this example.
In FIG. 13, in order to reduce the sixth unnecessary light component UL6, a circularly polarizing plate is disposed on the outermost surface of the front plate in the display device of Example 1.
The circularly polarizing plate has a configuration in which a third polarizing plate PL3 and a quarter-wave plate QW are laminated, and the slow axis of the quarter-wave plate QW forms 45 degrees with respect to the absorption axis of the polarizing plate. .
At this time, the light that has passed through the polarizing plate passes through the quarter-wave plate QW, is reflected by the reflective layer RE, and again passes through the quarter-wave plate QW. When the light enters the polarizing plate again, it is absorbed by the polarizing plate. As a result, the sixth unnecessary light component UL6 is reduced and outdoor visibility is improved.

  The quarter-wave plate QW may be a film prepared by stretching polycarbonate or a cycloolefin organic polymer, or alternatively, a photopolymerizable low-molecular liquid crystal is applied on an alignment film and aligned. It may be formed by photopolymerization. The latter has an advantage that the thickness can be reduced as compared with the former although the number of manufacturing steps is large.

Under actual use conditions, light incident obliquely with respect to the normal direction of the front plate may become the sixth unnecessary light component UL6.
For such sixth unnecessary light component UL6, the viewing angle characteristics of the quarter-wave plate QW are optimized, and the viewing angle range showing the function close to the quarter-wave plate QW is expanded, thereby polarizing plate Can absorb more.
To maintain the Δnd in the normal direction of the quarter-wave plate QW at a quarter-wave, and to expand the viewing angle range showing the function close to the quarter-wave plate QW, the refractive index in the thickness direction _nz is optimized.
The refractive index in a slow axis direction n _x in the _plane, and the refractive index of the fast axis direction and n _y, by a n _z ≒ n _x by increasing the refractive index in the thickness direction, all the viewing direction Can be absorbed relatively well.

Alternatively, if the quarter-wave plate QW is a wide-band quarter-wave plate QW, the above-described polarization state conversion can be realized in a wider wavelength range in the visible wavelength range. Specifically, the broadband quarter-wave plate QW is formed by stacking a half-wave plate and a quarter-wave plate QW, and the quarter-wave plate QW is closer to the reflective layer RE. Arrange to do. Further, when the azimuth angle is defined counterclockwise with the transmission axis of the third polarizing plate PL3 as 0 degree, the slow axis azimuth angles θ _h and θ _q of the half-wave plate and quarter-wave plate QW are Set according to the following formula.

2θ _q = ± 45 ° + θ _h (1)

  In this embodiment, the circularly polarizing plate is disposed on the outermost surface of the front plate. However, if the circularly polarizing plate is disposed closer to the user side than the light extraction structure, it functions to prevent reflection. Therefore, for example, in the structure in which the light extraction structure is formed on the surface of the front plate close to the optical shutter, the polarizing plate is pasted on the surface of the front plate away from the optical shutter, and the quarter wavelength plate QW is extracted from the light. It may be formed between the structure and the front plate.

<< Ninth embodiment >>
Hereinafter, a ninth embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

In this example, paying attention to the fourth unnecessary light component UL4, an attempt was made to improve the outdoor visibility of the display element of the present invention.
In Example 1, when light incident from the outside enters the light scattering layer, it may be scattered by the light scattering layer. In addition to the blue light diffuser BD, the red phosphor RF and the green phosphor GF also have a structure in which phosphor particles are dispersed in a resin, and if the phosphor particles are sufficiently larger than the wavelength of incident light from the outside, Light scattering is shown by the difference in refractive index between the resin and the phosphor particle interface. If the 4th unnecessary light component UL4 radiate | emits the front of a front board and is observed by the user, it will become a cause of outdoor visibility fall.

FIG. 14 is a cross-sectional view including three pixels of the display device of this embodiment.
In the embodiment shown in FIG. 14, the amount of the phosphor or light scatterer contained in the light extraction structure or the thickness of the layer containing the phosphor or light scatterer is kept constant while the light extraction structure The size was reduced from that of Example 1, and the area ratio of the light extraction structure on the front plate was reduced.
In this case, outdoor visibility can be improved because the ratio of the external light incident on the light scattering layer can be reduced according to the area ratio while keeping the display light amount constant.

In the ideal case where the characteristics of the condensing means are very good and the collimated light source BLS light can be condensed at one point of the light incident part, the effect of outdoor visibility can be obtained only by the above measures, And no side effects occur.
However, since the characteristics of the collimated light source BLS light and the light collecting means are actually inferior to the ideal characteristics assumed in principle, the collimated light source BLS light is incident on the periphery of the light incident part. It can happen. In that case, the following side effects occur.

If the light extraction structure is reduced, the light incident portion is also reduced, so that the proportion of collimated light source BLS light that can be condensed on the light incident portion is also reduced.
Along with this, the proportion of collimated light incident on the outside of the reflecting portion of the light extraction structure increases, and there are also cases where the light is extracted from the front plate directly off the light extraction structure.
In the former case, if the light is reflected outside the reflecting portion of the light extraction structure, the light travels again toward the optical shutter.
If this is reflected inside the optical shutter and passes through the incident part of another light extraction structure, it becomes the first unnecessary light component UL1 in FIG. 10A, which causes a decrease in display characteristics such as a decrease in contrast ratio.
Even in the latter case, the light that should be converted into red or green is emitted from the display device as blue, so that it becomes the second unnecessary light component UL2 in FIG. Cause.
In addition to reducing the size of the light extraction structure, measures for these problems must be taken at the same time.

If you cover all parts of the front plate where the light extraction structure does not exist with a light absorber, the stray light component reflected by the outside of the light extraction structure and the blue light component directly emitted from the front plate are almost completely absorbed. As a result, image quality deterioration can be prevented.
However, since the ratio of absorbing the blue light of the collimated light source BLS without using it for display increases, the light use efficiency decreases.

Even if an ideal microlens ML is formed, the light of the collimated light source BLS may not be completely condensed on the light incident part. The cause is the collimating property of the collimated light source BLS as described in the second embodiment. By not being perfect.
In the second embodiment, the microlens ML is formed on the first polarizing plate PL1 or the first substrate SU1, but since the distance between the light incident portion and the microlens ML is closer, this is a smaller light incident. Incomplete collimated light with respect to the portion can be collected better.

By combining the measures as described above, outdoor visibility can be improved while maintaining light utilization efficiency.
If the phosphor distribution in the red phosphor RF and the green phosphor GF is made more uniform so that the phosphor distribution is sufficiently smaller than the wavelength of incident light from the outside, at least the red phosphor RF and the green fluorescence Generation of the fourth unnecessary light component UL4 in the body GF can be prevented.
Specifically, the organic phosphor may be dispersed in the resin, and the organic polymer and the organic phosphor molecule constituting the resin may be uniformly mixed at the molecular level.

<< Tenth Embodiment >>
Hereinafter, a tenth embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

In this embodiment, in order to reduce the generation of the fourth unnecessary light component UL4, the fifth unnecessary light component UL5, and the sixth unnecessary light component UL6 shown in FIG. Measures were taken by changing
FIG. 15 is a cross-sectional view including three pixels of the display device of this embodiment.
The light extraction structure is composed of a first reflection layer RE and a second reflection layer RE, and the second reflection layer RE is distributed on a slope other than the vicinity of the apex of the conical structure, like the reflection layer RE of the first embodiment. It was. The first reflecting plate has a reflecting surface parallel to the substrate plane of the front plate, and is distributed near the center of the bottom of the conical structure formed by the second reflecting layer RE. The light diffuser is distributed on the surface of the first reflector that is close to the optical shutter.

The light extraction structure of this example was prepared by the following method.
An aluminum film is formed on the surface of the third substrate SU3 close to the optical shutter, and this is patterned so that the planar shape is a circle, thereby forming the first reflective layer RE.
Next, each light scattering layer, that is, a red phosphor RF, a green phosphor GF, and a blue light scatterer are sequentially formed on the first reflective layer RE. At this time, each light scattering layer is prevented from being distributed as far as possible from the first reflective layer RE. In addition, the end shape of each light scattering layer need not be particularly inclined.
A transparent resin layer is formed thereon, and patterning is performed so that the planar shape is a circle around each light scattering layer. An inclination is given to the end shape at the time of processing, and a rotating body structure having a trapezoidal cross section is formed on each light scattering layer.

An aluminum film is formed thereon, and this is patterned to remove the aluminum film from the upper part of the rotating body structure, thereby forming a second reflective layer RE and a light incident part.
Finally, a transparent resin is applied so as to cover the second reflective layer RE and the entire light incident portion, and the unevenness due to the light extraction structure is flattened.

  The blue light of the collimated light source BLS passes through the light incident part and enters the light diffuser. At this time, the scattered light emitted from the light diffuser travels toward the second reflector. This is reflected again by the second reflector and goes outward. Since incident light from the outside cannot directly enter the light scatterer, the amount of scattering caused by the light scatterer is reduced.

<< Eleventh Embodiment >>
Hereinafter, an eleventh embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

FIG. 16 shows an optical path inside the light extraction structure.
In FIG. 16, a green phosphor GF is shown as a representative of three types of light scatterers.
FIG. 16A shows a case where the shape of the light extraction structure is a rotating body, that is, the planar shape is circular.
Most of the scattered light emitted from the light scatterer is reflected by the reflective layer RE. However, if the planar shape of the light extraction structure is circular, the azimuth angle of the optical path does not change during reflection. Since the scattered light emitted from the light scatterer has an isotropic azimuth distribution from the beginning, the scattered light can be emitted with the same intensity with respect to all azimuth directions.

In this embodiment, the light extraction structure has a shape different from that of the rotating body, and an azimuth distribution is given to the diffused light intensity.
The planar shape of the light extraction structure of this embodiment is shown in FIG.
In this example, the mask pattern of the photolithography process when creating the light extraction structure was changed, and the planar shape at the time of processing was changed from a circle to an ellipse.
As shown in FIG. 16B, when the scattered light emitted from the light scatterer is reflected by the reflective layer RE, the azimuth angle of the optical path changes so as to approach the major axis direction of the ellipse. Thereby, the scattered light component in the major axis direction of the ellipse can be increased, and the scattered light component in the minor axis direction can be decreased.
The azimuth angle dependence of the emission intensity can be controlled by the ellipticity of the light extraction structure. That is, the azimuth distribution of emission intensity becomes more isotropic when the ellipticity is close to 1, and the anisotropy increases when the ellipticity is increased.

For example, in a display device for a mobile phone, peeping prevention from the left and right directions is required when used in a crowd, and a user who puts a peeping prevention filter on the display surface is also seen.
Such a peeping prevention filter is not preferable because the transmittance in the normal direction is reduced in addition to the effect of significantly reducing the transmittance in the oblique direction. Alternatively, when displaying one-segment broadcasting or the like and observing it with a large number of people, it is required to obtain a good display from a wider angle range in the left-right direction.

By giving an azimuth distribution to the diffused light intensity, it becomes possible to meet at least these requirements individually. Alternatively, if a rotation mechanism is introduced into the display unit of the mobile phone and combined with the above azimuth distribution, both requirements can be satisfied simultaneously.
That is, the light amount in the long side direction of the display element is further increased, and the light amount in the short side direction is further decreased. An example of the change in the shape of the mobile phone by the rotation mechanism, the arrangement of the display device, and the arrangement of the light extraction structure are shown in FIG. In the crowd, as shown in FIG. 17A, the display element is rotated so that the long axis of the light extraction structure is directed in the vertical direction and the direction with a small amount of light is directed in the horizontal direction. When observing with a large number of people, as shown in FIG. 17B, it is conceivable that the major axis of the light extraction structure is the horizontal direction and the direction with a large amount of light is directed to the left and right.

  In many cases, the display surface of the display device is rectangular, but if the ellipse's long axis is oriented in the long side direction of the display surface, a rotation mechanism is introduced into the display unit of the mobile phone as described above. In combination with the azimuth angle distribution of the emission intensity, it is possible to prevent peeping and improve the visibility when using a large number of people.

<< Twelfth Embodiment >>
Hereinafter, a twelfth embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

In this embodiment, the display device of the present invention has a large screen. In the embodiments so far, a collimated light source having a configuration in which the light emitting plate is provided with the blue light emitting diode BLS is used.
In this case, by increasing the number of blue light emitting diodes BLS arranged at the end, it is possible to maintain a constant luminance while making the screen larger.
In addition, it is possible to enlarge the screen by arranging the blue light emitting diode BLS directly under the light guide plate. An example in which a collimated light source having a larger area is created by arranging a plurality of light emitting diodes BLS directly below the light guide plate at a certain distance will be described below.

FIG. 18A is a cross-sectional view showing an example of the configuration of a large-area collimated light source BLS. A light-emitting diode is arranged behind the light guide plate LG to emit light in the normal direction of the light guide plate LG.
Since each light emitting diode can be regarded as a point light source, if the microlens ML is formed on the light guide around the light emitting diode, the light emitted from the light emitting diode can be converted into parallel light, and the collimated light source BLS is obtained. It is done.
In this case, in order to obtain a more uniform light emission intensity, the distance between the microlens ML and the light emitting diode needs to be approximately the same as the diameter of the microlens ML, and the thickness and weight of the entire display element increase.
Note that the microlens ML on the light guide plate LG is used for the purpose of converting the light emitted from the light emitting diodes into parallel light. Therefore, unlike the microlens ML of the light condensing means, the microlens ML does not correspond one-to-one with the pixels of the optical shutter. First, the light source light is irradiated to a wide area where a plurality of pixels are distributed.

In addition to using the microlens ML, the light emitted from the light emitting diode may be converted into parallel light using a reflector.
FIG. 19A is a cross-sectional view showing an example of the configuration of a large-area collimated light source BLS using a reflector.
Since each light emitting diode can be regarded as a point light source, it can be converted into parallel light by arranging the light emitting diode in the center of the reflective layer RE of the quadratic curved surface. In general, if a point light source is placed at one of the two focal points of the ellipse, the light is focused on the other focal point. However, the quadric surface is a special case of an elliptical surface and is equivalent to placing one focal point at an infinite distance. Therefore, the point light source can be converted into parallel light. The secondary curved reflection surface is formed by pressing a resin plate to create a concave structure having a secondary curved surface, and depositing an aluminum film thereon. Since most of the resin plates are hollow, the weight can be reduced.
Furthermore, as shown in FIG. 19 (b), if the reflecting surface is made into a Fresnel lens shape, the resin plate becomes a flat plate having a minute groove structure on the surface, so that further weight reduction and thickness reduction are possible. Become. The groove structure at this time has a concentric distribution centering on the light emitting diode.

  However, the degree of influence on the lower frame 103c depends on the distance between the lower frame 103c and the transformer TRANS (coil INVc).

The above is the collimated light source BLS using metal reflection, but it is also possible to use total reflection at the resin-air interface. An example of the configuration of such a large area collimated light source BLS is shown in FIG.
A concentric groove structure centering on the light emitting diode is formed on the resin plate, and the inclination angle of the groove is an angle satisfying total reflection at the resin-air interface. FIG. 18B shows a case where the refractive index of the resin is sufficiently high and the light from the light emitting diode can be directed in the normal direction with high efficiency.
When the refractive index of the resin is small, as shown in FIG. 18C, when the light is totally reflected by the groove structure of the light guide plate LG, the light traveling direction is inclined with respect to the normal direction of the light guide plate LG. In addition, the normal direction of the traveling direction is distributed radially around the light emitting diode.
In order to direct this in the normal direction, the prism sheet PS is disposed between the light guide plate LG and the optical shutter. The groove structure of the prism sheet PS is formed on the surface of the prism sheet PS close to the light guide plate LG, and the distribution thereof is concentric with the light emitting diode as the center. Utilizing refraction at the inclined surface of the prism sheet PS, the traveling direction of the light emitted from the light guide plate LG is directed to the normal direction.

  By using the large-area collimated light source BLS in which a plurality of light emitting diodes are arranged as described above, the display device of the present invention can be applied not only to a monitor of a mobile phone or a digital camera but also to a monitor of a personal computer or a television. .

<< Thirteenth embodiment >>
Hereinafter, an eleventh embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

  In the embodiments so far, the twisted nematic liquid crystal display element is used for the optical shutter. However, the optical shutter is not limited to this, and other types of liquid crystal display elements are also applicable.

For example, an electric field control birefringence liquid crystal display element is applicable.
The electric field control birefringence liquid crystal display element can be realized by making the following changes to the twisted nematic liquid crystal display element.
The alignment directions of the first alignment film AL1 and the second alignment film AL2 are antiparallel, and the alignment state of the liquid crystal layer LC is horizontal alignment when no voltage is applied. A retardation plate is arranged between the first substrate SU1 and the first polarizing plate PL1, or between the second substrate SU2 and the second polarizing plate PL2, and the slow axis direction thereof is the alignment direction of the liquid crystal layer LC. Perpendicular to

The absorption axis orientations of the first polarizing plate PL1 and the second polarizing plate PL2 are set so as to be orthogonal to each other and form 45 degrees with the liquid crystal alignment direction. As the voltage is applied, the alignment state of the liquid crystal layer LC changes and Δnd decreases. However, at a voltage at which Δnd of the liquid crystal layer LC matches Δnd of the retardation plate, the transmittance is minimized and dark display is obtained. If the Δnd of the liquid crystal layer LC, the Δnd of the retardation plate, and the applied voltage value are set so that Δnd of the liquid crystal layer LC changes by a half wavelength between this and the applied voltage giving a bright display, the bright display The transmittance can be increased.
In the present invention, the blue light emitting diode BLS is used as the collimated light source BLS, and the wavelength of the light passing through the liquid crystal display element is limited to around 460 nm. What is necessary is just to make it become a wavelength. As described above, in the electric field control birefringence type liquid crystal display element, the applied voltages for dark display and bright display can be arbitrarily set by Δnd of the liquid crystal layer LC and Δnd of the phase difference plate.

In addition, a vertical alignment type liquid crystal display element can also be applied to the liquid crystal display element.
The vertical alignment type liquid crystal display element can be realized by making the following changes to the twisted nematic type liquid crystal display element.
First, for the first alignment film AL1 and the second alignment film AL2, a vertical alignment film that makes the alignment direction of the adjacent liquid crystal layer LC perpendicular to the film surface is used.
Further, a chiral material is not added to the liquid crystal layer LC, and a liquid crystal material having a negative dielectric anisotropy is used as the liquid crystal material. When the voltage is applied, the liquid crystal layer LC changes its orientation so as to approach the horizontal alignment from the vertical alignment. An alignment control means for determining the orientation of the horizontal alignment at this time is added.

The orientation control means includes an electrode slit formed in the pixel electrode and a protrusion structure disposed on the common electrode or the pixel electrode. In a direct-view type vertical alignment type liquid crystal display element, in order to improve viewing angle characteristics, the alignment control means must be arranged so that the horizontal alignment direction is two or more in one pixel.
On the other hand, in the case of the present embodiment, the liquid crystal display element is used as an optical shutter, and the light source light mainly passes through the normal direction, so the horizontal orientation direction in one pixel is one direction. You just have to decide.
Since the transmittance-voltage characteristics in the normal direction do not depend on the horizontal orientation, the horizontal orientation may be different for each pixel.

In the vertical alignment type liquid crystal display element, normally closed transmission in which the transmittance increases with voltage application by arranging the absorption axes of the first polarizing plate PL1 and the second polarizing plate PL2 so as to be orthogonal to each other. A rate-voltage characteristic is obtained.
Further, if the first polarizing plate PL1 and the second polarizing plate PL2 are arranged so that the absorption axis directions of the first polarizing plate PL1 and the second polarizing plate PL2 form 45 degrees with respect to the horizontal orientation generated when a voltage is applied, higher transmittance can be obtained.
Further, in the vertical alignment type liquid crystal display element, Δnd of the liquid crystal layer LC when no voltage is applied is 0 nm in the normal direction, so that the absorption axis directions of the first polarizing plate PL1 and the second polarizing plate PL2 are orthogonal to each other. By arranging it, the transmittance when no voltage is applied can be made extremely low, and a display with a high contrast ratio can be obtained relatively easily.

Alternatively, an OCB (Optically Controlled Birefringence) type liquid crystal display element is also applicable. The OCB type liquid crystal display element can be realized by making the following changes to the twisted nematic type liquid crystal display element.
The alignment treatment directions of the first alignment film AL1 and the second alignment film AL2 are parallel to each other, whereby the liquid crystal alignment when no voltage is applied is the spray alignment. By applying a high voltage to this, it shifts to bend deformation, and a display state is obtained.
While maintaining the bend deformation, the Δnd of the liquid crystal layer LC is changed by changing the tilt angle distribution, and by combining this with the retardation plate, dark display and bright display can be performed in the same manner as the electric field control birefringence type liquid crystal display element. The applied voltage can be arbitrarily set.
OCB type liquid crystal display elements have a shorter response time than electric field controlled birefringence type liquid crystal display elements and twisted nematic type liquid crystal display elements, and are capable of displaying better moving images even under severe conditions such as low temperatures. It is.

  As described above, in the present invention, the liquid crystal display element is used as an optical shutter, and the viewing angle characteristic of the liquid crystal display element itself is not necessary. Therefore, the optimum liquid crystal display element can be selected according to the application, and the vertical alignment type liquid crystal display If an element is used, the contrast ratio can be improved, and if an OCB type liquid crystal display element is used, response characteristics can be improved.

Furthermore, the optical shutter of the present invention is not limited to a liquid crystal display element, and other types of display elements can be applied as long as they are non-light-emitting display elements that modulate light transmittance. For example, a display element that switches between a light transmission state and a non-transmission state by moving a metal foil piece by an electric field may be used.
Such display elements are introduced by Nesbitt Hagood, Roger Batron, Tim Brosnihan, John Fijol, Jignesh Gandhi, Mark Halfman, Richard Payne, J. Lodewyk Steyn, from page 1278 to 1281 of Society for Information Display 2007 Digest. Has been. It is characterized by high-speed response and high transmittance that exceed those of liquid crystal display elements.

  According to the present invention, a display element with a wide color reproduction range and excellent viewing angle characteristics and a high contrast ratio and low power consumption can be obtained. When used in a monitor of a mobile phone or a digital camera, the battery driving time is improved and the image quality is improved. If it is used for a monitor of a television or a personal computer, a high-quality display can be obtained while reducing power consumption.

It is sectional drawing which shows the structure of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is a perspective view showing relative arrangement of micro lens ML array MLA, a pixel, and a light extraction structure. It is a schematic diagram which shows the classification | category of the fluorescence by the optical path after light emission. 10 is a cross-sectional view illustrating a configuration of a display device according to Example 4. FIG. It is a schematic diagram which shows polar angle distribution control of the diffused light by the angle of the reflective surface of a light extraction structure. 10 is a cross-sectional view illustrating an example of a configuration of a display device according to Example 5. FIG. 10 is a cross-sectional view illustrating an example of a configuration of a display device according to Example 5. FIG. 10 is a cross-sectional view illustrating an example of a configuration of a display device according to Example 5. FIG. 10 is a cross-sectional view illustrating an example of a configuration of a display device according to Example 5. FIG. It is a schematic diagram which shows the classification | category of the unnecessary light which may arise in this invention. 10 is a cross-sectional view illustrating a configuration of a display device according to Example 6. FIG. 10 is a cross-sectional view illustrating a configuration of a display device according to Example 7. FIG. 10 is a cross-sectional view illustrating a configuration of a display device according to Example 8. FIG. 10 is a cross-sectional view illustrating a configuration of a display device according to Example 9. FIG. 10 is a cross-sectional view illustrating a configuration of a display device according to Example 10. FIG. It is a schematic diagram which shows the azimuth distribution control of diffused light by the planar shape of the reflective surface of a light extraction structure. It is a figure at the time of applying the display apparatus of Example 11 to the mobile telephone with a rotation mechanism. 22 is a cross-sectional view illustrating an example of a configuration of a light source used in a display device according to Example 12. FIG. FIG. 33 is a cross-sectional view illustrating an example of the configuration of a light source used for the display device of Example 13; It is a figure which shows creation methods, such as a fluorescent substance layer, a light-scattering layer, and a light extraction structure. It is a figure which shows creation methods, such as a fluorescent substance layer, a light-scattering layer, and a light extraction structure. 6 is a cross-sectional view illustrating a configuration of a display device according to Embodiment 2. FIG. 10 is a cross-sectional view illustrating a configuration of a display device according to Example 3. FIG.

Explanation of symbols

SU3 ………… Third substrate BD ……………… Blue light diffuser GF ……………… Green phosphor RF …………… Red phosphor RE …………… Reflection layer OC ………… ... Flattening film ADH .... Adhesive layer PL1 ... ... First polarizing plate SU1 ... ... First substrate AL1 ... ... First alignment film LC ... ... ... Liquid crystal layer AL2 ... ......... Second alignment film SU2 ......... Second substrate PL2 ......... Second polarizing plate MLA ......... Microlens PS ............... Prism sheet LG ............... Light guide plate BLS ............ Blue light emitting diode GL ............ Scanning line SL ............ Signal wiring FL ............ Front emission component TL ............ Intra-layer propagation component RL ............ Back Outgoing component TRA ………… Total reflection angle UL1 ………… First unnecessary light component UL2 ………… Second unnecessary light component UL3 ………… Third Light component UL4 ………… Fourth unnecessary light component UL5 ………… Fifth unnecessary light component UL6 ………… Sixth unnecessary light component BL ……………… Blue color filter YE ……………… Yellow color filter PL3 ………… Third polarizing plate QW ………… Quarter wavelength plate AB ………… Absorbing layer RE1 ………… First reflecting layer RE2 ………… Second Reflection layer FL …………… Fresnel lens HC …………… Hard coat layer

Claims (11)

Constructed by laminating a collimating blue light source, an optical shutter and a front plate,
The front plate includes a red phosphor layer that converts blue light source light into red, a green phosphor layer that converts blue light source light into green, and a light scattering layer that scatters blue light source light,
The optical shutter has a plurality of independently controlled pixels,
A phosphor layer or a light scattering layer is provided on the front plate in a one-to-one correspondence with the pixels of the optical shutter,
In a liquid crystal display device that condenses light source light on a phosphor layer or a light scattering layer through pixels on the optical shutter,
A light extraction structure for directing scattered light generated in the phosphor layer and the light scattering layer to the user side on the front plate is provided,
The light extraction structure is
It consists of a first reflector and a second reflector, and the first reflector is distributed on the slope except for the vicinity of the apex of the conical structure,
The conical structure is
It is arranged with the vertex facing the light source side,
The second reflector is
Arranged on the bottom side of the conical structure,
On the side close to the light source of the second reflector,
The light scattering layer or the fluorescent layer is laminated,
The liquid crystal display device, wherein the light source light is condensed and irradiated onto the light scattering layer or the fluorescent layer through the vicinity of the apex of the cone-shaped structure using a microlens array. Constructed by laminating a collimating blue light source, an optical shutter and a front plate,
The front plate includes a red phosphor layer that converts blue light source light into red, a green phosphor layer that converts blue light source light into green, and a light scattering layer that scatters blue light source light,
The optical shutter has a plurality of independently controlled pixels,
A phosphor layer or a light scattering layer is provided on the front plate in a one-to-one correspondence with the pixels of the optical shutter,
In a liquid crystal display device that focuses light source light on a phosphor layer or a light scattering layer through pixels on the optical shutter,
A light extraction structure for directing scattered light generated in the phosphor layer and the light scattering layer to the user side on the front plate is provided,
The light extraction structure is constituted by a reflector inclined with respect to the plane of the front plate,
The phosphor is distributed only near the apex of the cone-shaped structure;
The light extraction structure is
It is a reflector distributed on the slope excluding the vicinity of the apex of the conical structure,
The conical structure is
Placed with the vertices facing the light source,
The light scattering layer or fluorescent layer is
Formed inside the reflector,
Condensing the light source light on the phosphor layer or light scattering layer on the front plate using a microlens array,
A liquid crystal display device, wherein the light scattering layer or the fluorescent layer is irradiated with the light source light through the vicinity of the apex of the conical structure. The optical shutter is
The liquid crystal display device according to claim 1, which is a liquid crystal display element . The liquid crystal display element is
A first substrate, a second substrate, a first polarizing plate, a second polarizing plate, and a liquid crystal layer sandwiched between the first substrate and the second substrate,
A pair of pixel electrodes and a common electrode on a display portion on a surface close to the liquid crystal layer between the first substrate or the second substrate;
The liquid crystal display device according to claim 3 , wherein the first polarizing plate and the second polarizing plate are laminated on top and bottom of the first substrate and the second substrate . The front plate is provided with a circularly polarizing plate ,
The liquid crystal display device according to claim 1 or 2 in which is arranged close to the user than the light extraction structure. The liquid crystal display device according to the microlens array to claim 1 or 2 in which is arranged on the front plates and the light shutter. The liquid crystal display device according to claim 1 or 2 in which is arranged between the microlens array the optical shutter and a blue light source. The liquid crystal display device according to claim 1 or 2 is obtained by arranging the light absorbing layer to a nonexistent portion of the light extraction structure on the front plate. The liquid crystal display device according to claim 1 , wherein a blue color filter is disposed between the optical shutter and the front plate . The liquid crystal display device according to claim 1 , wherein an interference film that passes the light source light and reflects fluorescence toward a user is disposed between the optical shutter and the front plate . The phosphor layer is
The liquid crystal display device according to claim 1 , wherein the light source light is completely absorbed when the amount of light source incident on the phosphor layer is maximized .

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