JP2013254071A - Fluorescent substrate and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent substrate and a display device, capable of reducing influence of external light entered into a fluorescent substance and efficiently emitting fluorescent light generated in the fluorescent substance.SOLUTION: A fluorescent substance layer 13 is formed of a liquid crystal polymer (liquid crystal material) having a dichroic dye DD (a dichroic fluorescent dye) dissolved and dispersed. A fluorescent substance layer 13 is formed by charging the liquid crystal polymer having the dichroic dye DD dissolved and dispersed, into regions partitioned by partition walls 15. The dichroic dye has a molecular structure extended long in uniaxial direction. The fluorescent substance layer 13 is aligned so that a normal line of the transition dipole moment of the dichroic dye DD is within an angle range of less than ±45° to one surface 11a of a substrate 11.

Description

   The present invention relates to a phosphor substrate that emits fluorescence upon incidence of excitation light, and a display device including the same.

   In recent years, the need for flat panel displays has increased with the advancement of information technology. Examples of the flat panel display include a non-self-luminous liquid crystal display (hereinafter abbreviated as LCD), a self-luminous plasma display (hereinafter abbreviated as PDP), inorganic electroluminescence, and the like. Sense (inorganic EL) displays, organic electroluminescence (hereinafter also referred to as “organic EL” or “organic LED”) displays, and the like are known. In particular, liquid crystal displays have low power consumption, low cost, and high performance ( Higher brightness and higher color reproducibility) than other displays.

   A liquid crystal display generally performs color display by additively mixing display pixels composed of three primary colors of blue, red, and green. Conventional liquid crystal display devices generally have a configuration in which three primary colors are displayed using a color filter that selectively transmits blue light, red light, and green light, and a white light source. However, when a white light source is used, there are many wavelength components cut by the color filter, and there is a problem in that the light use efficiency is poor. There is also a problem that luminance and color purity change depending on the viewing angle.

   As one of the solutions, the fluorescent color display device described in Patent Document 1 or the liquid crystal display module described in Patent Document 2 includes a light source that emits excitation light, and the excitation light emits red, green, and blue light. There has been proposed a color display device in which a phosphor that emits fluorescent light is disposed corresponding to a pixel of a liquid crystal display element, the liquid crystal display element is used as an optical shutter, and color display is performed by fluorescence of the phosphor.

   In a liquid crystal display device having such a phosphor, light is emitted between the light emitting region and the liquid crystal display element in order to effectively use the fluorescence emitted from the phosphor and emitted toward the liquid crystal display element. A display device in which a reflective film is formed has been proposed (see, for example, Patent Document 3). As an example, according to the color liquid crystal display device disclosed in Patent Document 1, a light reflecting film is formed between the light emitting region by the excitation light and the liquid crystal display element, and out of the light generated in the light emitting region, The light directed to the liquid crystal display element in the opposite direction is reflected toward the emission side by this light reflection film, whereby the light generated in the light emitting region is efficiently emitted and a bright color display is realized.

JP 60-50578 A Japanese Patent Laid-Open No. 7-253576 JP 2009-134275 A

  However, in the invention disclosed in Patent Document 3 described above, in an environment where external light is incident from the emission side of the fluorescence, such as outdoors in the daytime or under bright illumination, the incident external light is reflected by the light reflection film again. Emitted. As a result, there has been a problem that the visibility of the display is lowered and a high-quality display cannot be obtained.

   The present invention has been made in view of the above circumstances, and a phosphor substrate capable of efficiently emitting fluorescence generated in the phosphor while reducing the influence of external light incident on the phosphor, and An object is to provide a display device.

In order to solve the above problems, some embodiments of the present invention provide the following phosphor substrate and display device.
That is, the phosphor substrate of the present invention includes a light-transmitting substrate, a phosphor layer and a phosphor reflector layer that are stacked in order on one surface of the substrate, and the substrate and the phosphor reflector layer. A phosphor substrate comprising at least a partition wall that divides the phosphor layer into a plurality of pixel units,
In each pixel region defined by the partition walls, a light absorption layer facing the phosphor layer from one surface of the substrate is provided, and the phosphor layer is disposed between the light absorption layer and the fluorescence reflector layer. The phosphor layer contains a dichroic dye, and the constituent molecules of the dichroic dye are oriented in an angle range in which a normal line of a transition dipole moment is less than ± 45 ° with respect to one surface of the substrate. It is characterized by that.

The constituent molecules of the dichroic dye are characterized by aligning a liquid crystal material as a medium.
A light control layer for bending incident light is further disposed on the surface opposite to the surface where the fluorescent reflector layer faces the fluorescent material layer.
The phosphor layer includes the dichroic dye and an absorbing dye having a smaller dichroic ratio than the dichroic dye, and the absorbing dye receives the energy of the wavelength emitted from the dichroic dye and emits light. It is a conversion material.

In addition, the phosphor substrate of the present invention includes a light-transmitting substrate, a phosphor layer and a phosphor reflector layer that are sequentially stacked on one surface of the substrate, and the substrate and the phosphor reflector layer. A phosphor substrate comprising at least a partition wall that divides the phosphor layer into a plurality of pixel units,
In each pixel region defined by the partition walls, a light absorption layer facing the phosphor layer from one surface of the substrate is provided, and the phosphor layer is disposed between the light absorption layer and the fluorescence reflector layer. The barrier ribs are formed to have a width that increases from the substrate toward the fluorescent reflector layer, and the side surfaces of the barrier ribs form an inclined surface.

A light reflecting layer is further formed on the end surface of the light absorbing layer facing the fluorescent reflector layer.
The fluorescent reflector layer and the light reflective layer are each composed of a low refractive index layer having a refractive index lower than that of the phosphor layer.
The refractive index ratio between the refractive index n1 of the phosphor layer and the refractive index n2 of the fluorescent reflector layer and the light reflecting layer is n1 / n2> 1.15.

The inclined surface has fluorescent reflectivity.
The inclined surface further divides the pixel region into a plurality of small regions.
The inclined surface is inclined with respect to one surface of the substrate in an angle range of 39 ° or more and less than 90 °.

The light absorber divides each pixel region into a plurality of openings on one surface side of the substrate.
A filter layer that cuts at least light in a wavelength range that excites the phosphor layer to emit fluorescence out of external light incident from the substrate is formed on the substrate side of the phosphor layer. Features.
A surface of the light reflecting layer facing the fluorescent reflector layer is covered with the fluorescent layer.

   The display device of the present invention is formed by overlapping the phosphor substrate according to each of the above-described items, a light source that emits light source light toward the phosphor substrate, and the phosphor substrate. And a display unit for adjusting the amount of incident light source light.

   According to the present invention, it is possible to realize a phosphor substrate and a display device with high visibility without deteriorating the characteristics of outgoing light due to the incidence of external light.

It is sectional drawing which shows the display apparatus provided with the fluorescent substance substrate which concerns on 1st embodiment. It is a structural diagram which shows an example of a dichroic dye and a liquid crystal monomer. It is explanatory drawing and a graph which show the effect | action of a dichroic dye. It is explanatory drawing which showed the effect | action of the dichroic dye by orientation It is a graph which shows the relationship between fluorescence emission angle and relative fluorescence intensity. It is sectional drawing which shows the effect | action of a light control layer. It is sectional drawing which shows the phosphor substrate which concerns on 2nd embodiment. It is explanatory drawing which shows the effect | action of the phosphor substrate which concerns on 2nd embodiment. It is sectional drawing which shows the display apparatus provided with the fluorescent substance substrate which concerns on 3rd embodiment. It is a principal part expanded sectional view which shows the effect | action of a fluorescence reflection layer. It is a graph which shows the relationship between refractive index ratio and relative component amount. It is a top view which shows the mode of a pixel area. It is a top view which shows the example of a division | segmentation of a pixel area. It is a principal part expanded sectional view which shows the inclined surface vicinity of a fluorescence reflection layer. It is a principal part expanded sectional view which shows the inclined surface vicinity of a fluorescence reflection layer.

  Hereinafter, with reference to the drawings, an embodiment of a phosphor substrate according to the present invention and a display device including the phosphor substrate will be described. The following embodiments are specifically described for better understanding of the gist of the invention, and do not limit the present invention unless otherwise specified. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, there is a case where a main part is shown in an enlarged manner for the sake of convenience. Not necessarily.

(First embodiment)
FIG. 1 is a schematic cross-sectional view showing a display device including the phosphor substrate according to the first embodiment.
The phosphor substrate 10 includes a light transmissive substrate 11, and a filter layer 12, a phosphor layer 13, and a fluorescence reflector layer 14 that are sequentially stacked on one surface 11 a of the substrate 11. FIG. 1 shows a state in which the substrate 11 is laminated from the one surface 11a toward the lower side in the drawing.

   Further, a light source (backlight, excitation light source) 19 that excites the phosphor layer 13 and a light source light L emitted from the light source 19 are turned on and off adjacent to the fluorescent reflector layer 14 of the phosphor substrate 10. A liquid crystal panel (display unit) 21 is arranged to constitute a display device 20. Further, the light source light (incident light) L is bent between the liquid crystal panel (display unit) 21 and the fluorescent reflector layer 14, that is, on the opposite side of the surface where the fluorescent reflector layer 14 faces the fluorescent layer 13. It is preferable that a light control layer (light bending layer) 22 to be formed is formed.

   On the side surface of the phosphor layer 13 along the stacking direction, partition walls 15 are formed that partition the phosphor layer 13 into, for example, one pixel unit. In the following description, when the pixel region E is referred to, an inner region surrounded by the partition wall 15 is shown. The partition wall 15 is formed so as to increase in width from the substrate 11 toward the fluorescent reflector layer 14, whereby the side surface of the partition wall 15 forms an inclined surface. The partition wall 15 is made of a material having fluorescence reflectivity that reflects the fluorescence F generated in the phosphor layer 13.

   Light absorption layers 16 and 17 are formed between the one surface 11 a of the substrate 11 and the partition wall 15 and between the phosphor layer 13, respectively. Among these, the light absorption layer 16 is formed so as to overlap the partition wall 15 so as to partition the filter layer 12 in units of one pixel.

   On the other hand, the light absorption layer 17 is formed so as to face the phosphor layer 13 from the one surface 11 a of the substrate 11 in the pixel region E defined by the partition 15. Further, the light absorption layer 17 may be formed so as to divide one pixel region E into a plurality of, for example, eight. In addition, the light absorption layer 17 should just be formed as a member integral with the light absorption layer 16 which comprises the outer edge part of the pixel area | region E. FIG.

   For example, such a light absorption layer 17 protrudes from the one surface 11a of the substrate 11 toward the phosphor layer 13 with the same thickness as the filter layer 12 in the stacking direction (thickness direction) S, and the end surface 17a thereof is the phosphor layer. 13 may be formed so as to face (expose) 13. That is, the phosphor layer 13 is interposed between the end face 17 a of the light absorption layer 17 and the fluorescent reflector layer 14.

   Further, a light reflection layer 18 is formed so as to overlap the end surface 17 a of the light absorption layer 17. For example, the light reflecting layer 18 may be formed so as to protrude from the end face 17a of the light absorbing layer 17 into the phosphor layer 13 with a predetermined thickness. That is, the surface 17 a where the light absorption layer 17 faces the fluorescent reflector layer 14 is covered with the phosphor layer 13, and the phosphor layer 13 is between the light absorption layer 17 and the fluorescent reflector layer 14. It has become.

  The phosphor layer 13 is composed of a liquid crystal polymer in which a dichroic dye (dichroic fluorescent dye) DD is dissolved and dispersed. The phosphor layer 13 is formed by filling a liquid crystal polymer (liquid crystal material) in which the dichroic dye DD is dissolved and dispersed into a region partitioned by the partition walls 15. The dichroic dye has a molecular structure extending in a uniaxial direction.

  In the phosphor layer 13, the normal of the transition dipole moment of the dichroic dye DD is oriented in an angle range that is less than ± 45 ° with respect to the one surface 11 a of the substrate 11. In order to orient the dichroic dye DD in an angular range of less than ± 45 ° with respect to the one surface 11a of the substrate 11, the upper surface of the phosphor layer 13, that is, between the phosphor layer 13 and the light absorption layers 16 and 17 is used. The vertical alignment film 23 is preferably formed.

The light control layer (light bending layer) 22 refracts the light beam direction of the light source light L emitted from the light source 19 to facilitate absorption by the dichroic dye DD oriented in the phosphor layer 13. Such a light control layer 22 has dispersed, for example, fine particles having a particle size of several hundred nm to several μm in a transparent resin so as to efficiently scatter the light source light L forward by an action such as scattering, refraction, or reflection. Consists of things. As the material of the fine particles, for example, TiO ₂ or another resin having a refractive index different from that of the resin may be used.

Hereinafter, although each structural member which comprises the fluorescent substance substrate 10 which concerns on this embodiment mentioned above, and its formation method are demonstrated concretely, this invention is not limited to these structural members and a formation method.
The substrate 11 used in this embodiment has a light emitting surface on the other surface 11b, and is made of a material that can transmit light, for example, an inorganic material substrate made of glass, quartz, etc., polyethylene terephthalate, polycarbazole, polyimide, or the like. Examples thereof include a plastic substrate or a substrate in which an insulating material made of an organic insulating material or the like is coated on the glass or resin.

   Furthermore, a substrate obtained by coating a plastic substrate with an insulating inorganic material is also preferable. As a result, when the plastic substrate is used as the substrate 11 of the phosphor substrate 10, it is possible to eliminate the deterioration of the phosphor layer 13 due to moisture permeation, which is the greatest problem. In addition, it is possible to eliminate leakage (short circuit) on the surface of the substrate 11.

   The phosphor layer 13 absorbs the light source light L of the light source (excitation light source) 19 and emits blue (B), green (G), and red (R) light, for example, a blue phosphor layer, a red phosphor layer, and a green color. It is composed of a phosphor layer and the like. Moreover, it is preferable to add phosphors emitting light of cyan and yellow to the pixels as necessary. Here, by setting the color purity of each pixel emitting light to cyan and yellow outside the triangle connected by the color purity points of red, green, and blue light emitting pixels on the chromaticity diagram, red, The color reproduction range can be further expanded as compared with a display device using pixels that emit three primary colors of green and blue.

   For example, the phosphor layer 13 may be formed by aligning and dispersing a dichroic dye as shown in FIG. Examples of the dichroic dye (dichroic fluorescent dye) include Coumarin-6 and DCM. Further, as a liquid crystal material for aligning in the angle range where the normal line of the transition dipole moment of these dichroic dyes is less than ± 45 ° with respect to the one surface 11a of the substrate 11, for example, as a liquid crystal monomer, FIG. What is shown in (b) is mentioned.

   As shown in FIG. 3A, when the dichroic dye is dissolved and dispersed in a liquid crystal polymer cured as a guest, an aligned state is realized as in the host liquid crystal. As a result, it is possible to obtain a phosphor substrate that has low light emission efficiency from one surface (Face) of the substrate and high light emission efficiency from the edge of the substrate, that is, the direction (Edge) perpendicular to the one surface of the substrate. FIG. 3B shows the wavelength of incident light and the absorption efficiency (absorption efficiency) of the dichroic dye in the (Face) direction and (Edge) direction of the phosphor substrate on which such a dichroic dye is oriented. Shows the relationship. According to this graph, it can be seen that the absorption efficiency in the (Edge) direction is significantly increased compared to the (Face) direction.

   As an example, a dichroic dye having a concentration of several percent (such as Coumarin-6) is dissolved in a liquid crystalline monomer (such as UCL-018) and filled in a region partitioned by a substrate coated with a vertical alignment film and a partition wall. . The liquid crystal monomer is not limited to this, and a monofunctional monomer and a polyfunctional monomer such as diacrylate are mixed in a ratio of, for example, about 1: 1 in order to impart thermal stability of liquid crystal alignment. . This substrate is sealed with a counter substrate on which the vertical alignment film is applied on the opposite side, and the mixture is put into a liquid crystal state (heated as necessary) to cure the monomer with ultraviolet rays or the like. . Thereafter, the counter substrate is peeled off to obtain a phosphor substrate.

   The thickness of the phosphor layer 13 is usually about 100 nm to 100 μm, but preferably 1 to 100 μm. If the film thickness is less than 100 nm, it is impossible to sufficiently absorb the excitation light (blue light emission) from the light source 19, resulting in a decrease in light emission efficiency and mixing of blue transmitted light with the required color. Problems such as deterioration of color purity arise. Further, in order to enhance absorption of excitation light (blue light emission) from the light source 19 and reduce blue transmitted light to such an extent that the color purity is not adversely affected, the film thickness is preferably 1 μm or more. Further, when the film thickness exceeds 100 μm, the blue light emission from the light source 19 is already sufficiently absorbed, so that the efficiency is not increased and only the material is consumed, leading to an increase in material cost.

   As the filter layer 12, a known color filter can be used. By providing the color filter, the color purity of red, green, and blue pixels can be increased, and the color reproduction range of the phosphor substrate 10 can be expanded. In the case of a blue phosphor layer, a blue filter layer 12 is formed, in the case of a green phosphor layer, a green filter layer 12 is formed, and in the case of a red phosphor layer, a red filter layer 12 is formed. Thus, it absorbs excitation light in which each phosphor is excited by the entry of external light.

   Thereby, it becomes possible to reduce / prevent emission of the phosphor layer 13 due to external light, and to reduce / prevent a decrease in contrast. By forming such a filter layer 12, it is possible to prevent the excitation light that is not absorbed and transmitted by the phosphor layer 13 from leaking to the outside. Therefore, it is possible to mix light emitted from the phosphor layer 13 and excitation light. Thus, it is possible to prevent a decrease in the color purity of light emission.

   The fluorescent reflector layer 14 is a material that transmits light in a wavelength region that becomes excitation light (for example, blue light emission) emitted from the light source 19 and that reflects the surface of the fluorescence emitted from the phosphor layer 13 excited by the excitation light. Consists of For example, when the excitation light is blue light emission, the fluorescent reflector layer 14 transmits blue light emitted from the light source 19 toward the phosphor layer 13 and when the phosphor layer 13 is a green phosphor layer. The green fluorescence excited by blue light emission is reflected toward the substrate 11.

   Such a fluorescent reflector layer 14 may be made of, for example, a low refractive index material having a refractive index lower than that of the phosphor layer 13, for example, a fluororesin having a refractive index of about 1.35 to 1.4, Examples thereof include transparent materials such as silicone resin having a refractive index of about 1.4 to 1.5, silica airgel having a refractive index of about 1.003 to 1.3, and porous silica having a refractive index of about 1.2 to 1.3. However, the present invention is not limited to these materials.

   The fluorescent reflector layer 14 is preferably composed of a wavelength selection film that reflects only fluorescence in a predetermined wavelength range. For example, the fluorescent reflector layer 14 only needs to reflect only the fluorescence in the wavelength region emitted by the excited phosphor layer 13 and transmit or absorb the light in other wavelength regions.

   The partition wall 15 surrounding the phosphor layer 13 can be formed by patterning a resin material such as a photosensitive polyimide resin, an acrylic resin, a methallyl resin, a novolac resin, or an epoxy resin by a photolithography method or the like. Further, in order to prevent contrast leakage due to light leakage or external light, a material obtained by patterning a material containing light-shielding particles such as carbon fine particles or metal oxides in the above-described photosensitive resin material may be used. . Further, the barrier may be formed by directly patterning the non-photosensitive resin material by screen printing or the like.

   The partition 15 is preferably formed of a material that reflects the fluorescence generated in the phosphor layer 13. By doing so, it is possible to reflect the fluorescent component escaping laterally from the phosphor layer 13 toward the substrate 11 on the emission side. It is also preferable to cover the surface of the partition wall 15 with a reflective material. Examples of such a reflective material include reflective metals such as aluminum, silver, gold, aluminum-lithium alloy, aluminum-neodymium alloy, and aluminum-silicon alloy.

   It is also preferable that the barrier ribs 15 are formed thicker than the phosphor layer 13. As a result, the phosphor layer 13 can be prevented from being damaged by external stress. In addition, as the shape of the partition wall 15, various shapes such as a trapezoid, a rectangle, and a circle can be adopted depending on the shape of the pixel.

   The light absorption layers 16 and 17 are made of a material capable of absorbing and attenuating external light, for example, sunlight or illumination light, which is incident from the other surface 11 b of the substrate 11 toward the phosphor layer 13. Such a light absorption layer 16 can be formed of, for example, a metal material such as chromium, a black resin, or the like. The film thickness of the light absorption layer 16 is preferably about 100 nm to 100 μm, for example, and more preferably about 100 nm to 10 μm.

   The light reflecting layer 18 formed on the end surface 17a of the light absorbing layer 17 is made of, for example, an aluminum or silver metal thin film, a scattering white resist in which fine particles are dispersed, or the like. In the case of using a scattering white resist, the same material as that of the partition wall 15 may be used and halftone exposure may be performed to form a desired film thickness. Further, the partition wall 15 and the light reflecting layer 18 may be formed in desired film thicknesses by a plurality of exposures. Alternatively, the light reflecting layer 18 and the partition wall 15 may be formed simultaneously by patterning a metal thin film.

   The light source (backlight) 19 may be a light emitting device that emits light source light that can excite the dichroic dye DD of the phosphor layer 13. For example, the light source light may be a surface-emitting light source that emits light having high directivity for exciting R, G, and B fluorescence or 400 to 500 nm blue light.

The operation and effect of the phosphor substrate 10 according to this embodiment having the above-described configuration will be described.
As in the conventional example shown in FIG. 4A, the phosphor layer of a conventional phosphor substrate using a dichroic dye has a transition dipole moment when the fluorescent dye is not oriented in a specific direction. The light is directed in a random direction, and the fluorescence emitted from this molecular assembly also has the same intensity in any direction.

On the other hand, as shown in FIG. 4 (b), to orient the dichroic dye, the fluorescent substrate of the present embodiment the normal direction of the transition dipole moment coincides with the theta _{phos 90} °, the theta _{phos 90} ° Fluorescence can be emitted selectively and strongly in the direction. The intensity I has a relationship of I = cos ² (90−θ _phos ) with the normal direction being maximized. When n _phos is 1.5 and the refractive index above and below the phosphor layer is 1, components with θ _phos of 42 ° (total reflection angle of the phosphor layer) or more are guided, so that the fluorescent dye is oriented. The more the fluorescent component is guided, the better. Since this relationship is established if the normal direction is less than ± 45 °, the dichroic fluorescent dye is oriented in an angular range where the normal of the transition dipole moment is less than ± 45 ° with respect to one surface of the substrate.

FIG. 5 is a graph obtained by measuring the relationship between the fluorescence emission angle θ _phos and the relative fluorescence intensity in the conventional example shown in FIG. 4A and the example of the present invention shown in FIG. According to this graph, for example, when n _phos is 1.5, a component having θn _phos of 42 degrees or more guides the phosphor layer. In the present invention, it can be seen that more fluorescent components can be guided.

FIG. 6 is an explanatory diagram showing the action of the light control layer (light bending layer) 22.
When the transition dipole moment of the dichroic dye DD is oriented in the vertical direction (thickness direction) of the phosphor substrate 10, the molecular axis that absorbs the light source light L is also directed in the same direction. Difficult to absorb highly directional light. For this reason, the light control layer 22 is inserted between the liquid crystal panel 21 and the fluorescent reflector layer 14 so that the light beam direction of the light source light L is bent to be easily absorbed by the dichroic dye DD. The excitation efficiency of the dichroic dye DD is increased by reflecting the light source light L with the fine particles of the light control layer 22 and tilting it.

   Thus, the fluorescence F generated by the dichroic dye DD of the phosphor layer 13 is reflected by the inclined surfaces of the light reflecting layer 18 and the fluorescent reflecting partition 15 and is emitted from the filter layer 12 to the outside through the substrate 11. .

   On the other hand, when natural light (external light) is incident on the phosphor substrate 10 from a predetermined angle, the light is attenuated while being repeatedly reflected between the light reflecting layer 18 and the fluorescent reflector layer 14. Thus, even when external light is incident from the outside of the phosphor substrate 10 due to the action of the light absorption layer 17 and the light reflection layer 18 formed in the pixel region E, most of the incident external light is absorbed. It is absorbed by the layer 17 or attenuated between the light reflecting layer 18 and the fluorescent reflector layer 14. Therefore, the external light incident on the phosphor substrate 10 is reflected inside the phosphor substrate 10, and the external light emitted from the phosphor substrate 10 again can be greatly reduced.

On the other hand, the fluorescence generated by the excitation of the phosphor layer 13 of the phosphor substrate 10 is not limited to the fluorescence reflector layer 14 even if the light absorption layer 17 is formed in the pixel region E and the aperture ratio is slightly reduced. By the action of the light reflection layer 18, most of the fluorescence generated in the phosphor layer 13 can be emitted to the outside of the phosphor substrate 10 without loss.
Therefore, by combining the phosphor substrate 10 of the present embodiment, a light source that excites the phosphor layer, and a display unit such as a liquid crystal display panel, an environment in which external light is likely to enter such as outdoors in the daytime or under illumination. In this case, a high-quality display with high visibility can be realized.

(Second embodiment)
FIG. 7A is a schematic sectional view showing a phosphor substrate according to the second embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to 1st embodiment, and the detailed description is abbreviate | omitted.
The phosphor substrate 30 of this embodiment includes a light transmissive substrate 11, a filter layer 12, a phosphor layer 33, and a phosphor reflector layer 14 that are sequentially stacked on one surface 11 a of the substrate 11. A partition wall 15 is formed on a side surface of the phosphor layer 33 along the stacking direction. The partition wall 15 is formed so as to increase in width from the substrate 11 toward the fluorescent reflector layer 14, and the side surface of the partition wall 15 forms an inclined surface. Light absorption layers 16 and 17 are formed between the one surface 11 a of the substrate 11 and the partition wall 15 and between the phosphor layer 13, respectively. A light reflection layer 18 is formed so as to overlap the light absorption layer 17.

  In the phosphor layer 13, the normal of the transition dipole moment of the dichroic dye B is oriented in an angle range that is less than ± 45 ° with respect to the one surface 11 a of the substrate 11. In order to orient the dichroic dye B in an angle range of less than ± 45 ° with respect to the one surface 11a of the substrate 11, the upper surface of the phosphor layer 13, that is, between the phosphor layer 13 and the light absorption layers 16, 17 is used. The vertical alignment film 23 is preferably formed.

  The phosphor layer 13 in this embodiment is composed of a dichroic dye (dichroic fluorescent dye) B and a liquid crystal polymer in which an absorbing dye A having a smaller dichroic ratio than the dichroic dye B is dissolved and dispersed. Has been. As shown in FIG. 7B, the absorbing dye A absorbs the light source light L incident through the fluorescent reflector layer 14 and emits excitation light E that excites the dichroic dye B. Thereby, the dichroic dye B emits fluorescence F. The absorbing dye A may be any wavelength conversion material that receives the energy of the wavelength emitted from the dichroic dye B and emits light.

  In general, there is a phenomenon called fluorescence resonance energy transfer (FRET) in which excitation energy does not become electromagnetic waves and moves directly by electron resonance between adjacent dye molecules. Arise. For this reason, the energy of light absorbed by one molecule (absorbing dye A: donor) is transferred to the other molecule (dichroic dye B: acceptor), and the dichroic dye B is a fluorescent molecule. In some cases, fluorescence is emitted. Such FRET efficiency decreases rapidly with distance as a function of the sixth power of the distance between both molecules.

  In the present embodiment, an absorption dye (fluorescent dye) A having a small dichroic ratio is used to absorb the light source light L, and a dichroic dye B having a large dichroism is used as a material that emits light to be guided. use. Thereby, the light source light L absorbed by the absorbing dye A having a small dichroic ratio is transferred to the dichroic dye B having a large dichroism, and the dichroic dye B is caused to emit fluorescence. The absorption dye A having a small absorption dichroic ratio has a small dependency on the absorption angle of the light source. And the fluorescence confinement efficiency is improved by the anisotropic light emission of the dichroic dye B having a large dichroism.

FIG. 8 is an explanatory diagram for explaining the operation of the present embodiment.
An example of forming the dichroic dye B and the absorbing dye A of the present embodiment will be shown.
The mixing ratio of the phosphor is the volume ratio of the phosphor layer to the resin.
Absorbing dye A: Lumogen (registered trademark) F Violet 570 0.2% manufactured by BASF
Dichroic dye B: BASF Lumogen® F Yellow 083 0.2%
When there is an absorption dye A and a dichroic dye B, and the absorption wavelength of the absorption dye A is on the shorter wavelength side than the absorption wavelength of the dichroic dye B, the distance between the absorption dye A and the dichroic dye B is sufficiently close ( When the overlap between the emission spectrum of the absorbing dye A and the absorption spectrum of the dichroic dye B is large, the excitation energy of the absorbing dye A efficiently moves to the dichroic dye B, and only the dichroic dye B Emits light.

In order to obtain a large rate constant, it is desirable that the following conditions are satisfied. (A) The overlap between the emission spectrum of the absorbing dye A and the absorption spectrum of the dichroic dye B is large.
(B) The absorption coefficient of the dichroic dye B is large.
(C) The distance between the absorbing dye A and the dichroic dye B is small.
Generally, the range in which Forster resonance energy transfer occurs is about 10 nm, and extends to about 20 nm if the conditions are met.

(Third embodiment)
FIG. 9 is a schematic cross-sectional view showing a display device including the phosphor substrate according to the first embodiment.
The phosphor substrate 40 includes a light transmissive substrate 11, and a filter layer 12, a phosphor layer 13, and a fluorescence reflector layer 14 that are sequentially stacked on one surface 11 a of the substrate 11.

   Further, a light source (backlight, excitation light source) 19 that excites the phosphor layer 13 and a light source light L emitted from the light source 19 are turned on and off adjacent to the fluorescent reflector layer 14 of the phosphor substrate 40. A liquid crystal panel (display unit) 21 is arranged to constitute a display device 50.

   On the side surfaces of the phosphor layer 13 along the stacking direction, partition walls (banks) 45 that partition the phosphor layer 13 into, for example, one pixel units are formed. The partition wall 45 is formed in an inverted trapezoidal shape whose width decreases from the substrate 11 toward the fluorescent reflector layer 14.

The partition wall (bank) 45 is filled with a light-transmitting resin (n _phos = 1.82) in which a fluorescent dye is dissolved and dispersed. Further, a fluorescent reflector layer 48 having an inclined surface Pf inclined according to the inverted trapezoidal shape of the partition wall 45 is disposed on the outer surface of the partition wall (bank) 45. The filter layer 12 is disposed between the partition wall (bank) 45 and the substrate 11. Accordingly, in the present embodiment, a configuration is adopted in which fluorescence is emitted from the phosphor layer 13 through the partition wall (bank) 45 and the filter layer 12.

   A light absorption layer 47 is formed between the one surface 11 a of the substrate 11 and the phosphor layer 13. Further, a light absorption layer 46 is also formed outside the filter layer 12. A low refractive index layer 49 is formed between the light absorption layers 46 and 47 and the filter layer 12 and the phosphor layer 13 and the partition wall 45.

   The fluorescent reflector layer 14 and the low refractive index layer 49 formed with the phosphor layer 13 in between are formed of, for example, a metal reflective film, a dielectric multilayer film, a low refractive index film, or the like. As an example, as shown in FIG. 10, the refractive index required when the fluorescent reflector layer 14 and the low refractive index layer 49 are formed of a material having a low refractive index both above and below was verified.

   Since the light emission in the phosphor layer 13 in which the fluorescent dye is not oriented in a random direction is radiated with the same luminous flux per unit solid angle (luminous intensity) in any direction, the substrate serving as the light extraction surface The amount of the “component in θc” taken out from the air 11 to the air and the “light guide component” that guides the phosphor layer 13 without being taken out are governed by a factor due to the critical angle θc. That is, the “component in θc” radiated to the outside of the phosphor layer 13 is limited to a solid angle corresponding to the critical angle θc within Ωc.

The ratio of light that falls within the solid angle Ωc corresponding to the critical angle is expressed by Equation 1 as ηc including the light extraction surface and the opposite back surface. This amount is a number that is an index indicating how much fluorescence can be extracted from the light extraction surface as “component in θc”, but when n _low = 1.3 and n _phos = 1.82 (n _{phos /1.8} n _low = 1.40, θc = 45.6 °) and a small value of 30%.

On the other hand, the amount of "light components" that guides a phosphor layer 13 is determined by the refractive index n _low refractive index n _phos and the low refractive index layer of the phosphor layer 13, the horizontal axis the refractive index ratio Each relative component amount is represented in a graph as shown in FIG. 11 (according to Snell's law, between the total reflection angle θc and the refractive index n _phos , n _low of the phosphor medium, θc = asin (n _low / n _phos ).

That is, if the refractive index ratio n _phos / n _low is larger than 1.15, the light amount of the “light guide component” becomes larger than the “component in θc”, which can be said to be an appropriate configuration requirement for the present invention. In the embodiment of the present invention (n _low = 1.3, n _phos = 1.82, refractive index ratio n _phos / n _low = 1.40, θc = 45.6 °), the relative component of the “light guide component” The amount was 70%, a value greater than 50%.

   FIG. 12 is a plan view in which the pixel region of the phosphor substrate 40 of the present embodiment is seen from the exit surface side, and a cross-sectional view taken along the line AA. A region corresponding to one pixel (hereinafter referred to as a pixel region) of the phosphor substrate 40 is a light non-transmissive region Nt in which a light absorption layer 47 having a rectangular central portion is formed. Then, a substantially B-shaped light transmission region Lt exposed by the filter layer 12 is formed so as to surround the periphery of the rectangular light absorption layer 47.

   Note that the light transmitting region Lt and the light non-transmitting region Nt in the pixel region of the phosphor substrate 40 may be formed in an arbitrary shape and in an arbitrary number, but the distance that the fluorescence is guided is not increased. In order to prevent fluorescence concentration quenching, a plurality of fluorescent reflector layers 48 constituting the inclined surface are preferably formed so as to divide the pixel region. Further, the light distribution characteristic of the fluorescence emission can be adjusted by the areas of the upper, lower, left and right fluorescent reflector layers 48.

FIG. 13 is a plan view showing an example of a division form in one pixel region by the fluorescent reflector layer.
In the phosphor substrate 40A shown in FIG. 13A, the pixel region is divided into three. That is, three independent light opaque regions Nt (light absorption layers) are arranged in the pixel region, and a substantially square light transmissive region Lt (filter layer) is arranged around each light opaque region Nt.
Further, in the phosphor substrate 40B shown in FIG. 13B, the pixel region is divided into eight. That is, four independent light opaque regions Nt (light absorption layers) are arranged in two rows in the pixel region, and a substantially square light transmissive region Lt (filter layer) is arranged around each light opaque region Nt. did.

FIG. 14 is an enlarged cross-sectional view of the main part showing the vicinity of the fluorescent reflector layer disposed on the outer surface of the partition wall (bank).
If the angle θ _ref of the inclined surface Pf in the fluorescent reflector layer 48 having the inclined surface Pf inclined following the inverted trapezoidal shape of the partition wall 45 is formed at a very shallow angle, there is no effect of suppressing external light reflection. Specifically, it is preferable that θ _ref > asin (1 / n _tr ) be formed so as to satisfy this relationship, because external light incident from an arbitrary incident angle θ _in is not emitted to the viewer side. (N _tr represents the refractive index of the transparent resin on which the reflective film is formed).

Table 1 shows that when the angle of the inclined surface Pf in the fluorescent reflector layer 48 is changed, external light with an incident angle θ _in of + 90 ° that is most difficult to satisfy the total reflection condition is emitted at which angle θ _out . (However, n _tr is set to 1.5).

According to the verification results shown in Table 1, if θ _ref is 39 ° or more, external light incident at an arbitrary angle θ _in cannot be returned to the viewer side inside 60 °. There are fewer opportunities to see light. Therefore, the inclined surface Pf is preferably formed so that θ _ref is an angle of 39 ° or more.
Further, if θ _ref is 42 ° or more, external light incident at an arbitrary angle θ _in cannot be returned to the observer side due to total reflection, so that θ _ref is inclined so as to be an angle of 42 ° or more. More preferably, the surface Pf is formed.

As shown in FIG. 15A, when the angle θ _ref of the inclined surface Pf of the fluorescent reflector layer 48 is formed to be 39 ° or more, much external light is totally reflected at the air interface on the extraction surface, and the light absorbing layer 47 is absorbed. Therefore, high visibility (light room CR characteristics) can be obtained even in an environment where bright outside light exists.

The angle θ _ref of the inclined surface Pf of the fluorescent reflector layer 48 affects the emission light distribution characteristics of the fluorescence from the phosphor substrate 40. Therefore, the inclined surface is formed to have a plurality of inclination angles, or the inclination angle ( (Taper angle) may have a distribution.
By controlling the angle distribution of the inclined surface Pf, the light is focused in the front direction to increase the front brightness as required, or the wide intensity is secured by increasing the output intensity on the high angle side, and the light distribution of the emitted light is adjusted. Is possible.

  DESCRIPTION OF SYMBOLS 10 ... Phosphor substrate, 11 ... Substrate, 12 ... Filter layer, 13 ... Phosphor layer, 14 ... Fluorescent reflector layer, 15 ... Partition, 17 ... Light absorption layer, 18 ... Light reflector layer, 20 ... Display device, DD: Dichroic dye.

Claims (15)

A light-transmitting substrate, a phosphor layer and a phosphor reflector layer that are sequentially stacked on one surface of the substrate, and the phosphor layer is partitioned into a plurality of pixels between the substrate and the phosphor reflector layer A phosphor substrate comprising at least a partition wall,
In each pixel region defined by the partition walls, a light absorption layer facing the phosphor layer from one surface of the substrate is provided, and the phosphor layer is disposed between the light absorption layer and the fluorescence reflector layer. And
The phosphor layer includes a dichroic dye, and the constituent molecules of the dichroic dye are oriented in an angle range in which a normal of a transition dipole moment is less than ± 45 ° with respect to one surface of the substrate. A phosphor substrate characterized by the following.    2. The phosphor substrate according to claim 1, wherein the constituent molecules of the dichroic dye are aligned using a liquid crystal material as a medium.    3. The phosphor substrate according to claim 1, wherein a light control layer for bending incident light is further disposed on a surface opposite to the surface of the phosphor reflector layer facing the phosphor layer.    The phosphor layer includes the dichroic dye and an absorbing dye having a smaller dichroic ratio than the dichroic dye, and the absorbing dye receives the energy of the wavelength emitted from the dichroic dye and emits light. The phosphor substrate according to claim 1, wherein the phosphor substrate is a conversion material. A light-transmitting substrate, a phosphor layer and a phosphor reflector layer that are sequentially stacked on one surface of the substrate, and the phosphor layer is partitioned into a plurality of pixels between the substrate and the phosphor reflector layer A phosphor substrate comprising at least a partition wall,
In each pixel region defined by the partition walls, a light absorption layer facing the phosphor layer from one surface of the substrate is provided, and the phosphor layer is disposed between the light absorption layer and the fluorescence reflector layer. And
The phosphor substrate is characterized in that the partition wall is formed so as to increase in width from the substrate toward the fluorescent reflector layer, and a side surface of the partition wall forms an inclined surface.    6. The phosphor substrate according to claim 5, wherein a light reflecting layer is further formed on an end surface of the light absorbing layer facing the fluorescent reflector layer.    The phosphor substrate according to claim 5 or 6, wherein the fluorescent reflector layer and the light reflective layer are formed of a low refractive index layer having a refractive index lower than that of the phosphor layer.    8. The refractive index ratio between the refractive index n1 of the phosphor layer and the refractive index n2 of the fluorescent reflector layer and the light reflecting layer is n1 / n2> 1.15. Phosphor substrate.    9. The phosphor substrate according to claim 5, wherein the inclined surface has fluorescence reflectivity.    The phosphor substrate according to claim 5, wherein the inclined surface further divides the pixel region into a plurality of small regions.    11. The phosphor substrate according to claim 5, wherein the inclined surface is inclined with respect to one surface of the substrate in an angle range of 39 ° or more and less than 90 °.    12. The phosphor substrate according to claim 1, wherein the light absorber divides each pixel region into a plurality of openings on one surface side of the substrate.    A filter layer that cuts at least light in a wavelength range that excites the phosphor layer to emit fluorescence out of external light incident from the substrate is formed on the substrate side of the phosphor layer. The phosphor substrate according to any one of claims 1 to 12, characterized in that:    14. The phosphor substrate according to claim 1, wherein a surface of the light reflecting layer that faces the phosphor reflector layer is covered with the phosphor layer.   The phosphor substrate according to any one of claims 1 to 14, a light source that emits light source light toward the phosphor substrate, and a layer formed on the phosphor substrate so as to be incident on the pixel of the phosphor substrate. And a display unit that adjusts the amount of the light source light.

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