JP2006308858A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device using fluorescent light, which can prevent image deterioration due to an afterglow and improves light emission efficiency. <P>SOLUTION: The display device 1 is provided with phosphor sections 2R and 2G containing phosphors absorbing an exciting light to emit a visible light, an optical shutter 3 which is provided in front of the phosphor sections 2R and 2G and transmit the visible light emitted by the phosphors that the phosphor sections 2R and 2G contain forward while adjusting the quantity of the light, and light sources 4 which are provided corresponding to the phosphor sections 2R and 2G and emit the exciting light for the phosphors toward the phosphor sections 2R and 2G. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device, and more particularly to a display device using fluorescence.

  Conventionally, a full color LED display (display device) using a combination of light emitting diodes emitting red (R), green (G), and blue (B) (hereinafter referred to as “LED” as appropriate) has been used for outdoor signage and the like. Widely used as a display. However, individual LEDs are large and difficult to miniaturize. For this reason, full-color LED displays are difficult to achieve high definition except for outdoor use, and are not generally used for indoor applications such as home displays.

In addition, when three different colors of LEDs are manufactured on the same substrate to reduce the size of a full color LED display, it is difficult to manufacture because three different manufacturing processes must be performed continuously and completely. .
Furthermore, since the red, green, and blue LEDs have different current-luminance characteristics, a control circuit corresponding to each color is required, which is inconvenient in practice.

  Therefore, in recent years, LEDs of the same emission wavelength are integrated and arranged on a substrate, and further, phosphor parts having phosphors emitting red, green, and blue fluorescence are formed, and each phosphor part is irradiated with excitation light. A color display for displaying an image by causing the phosphor portion to emit light in color has been proposed (Patent Documents 1 to 4).

JP-A-8-63119 JP-A-10-256673 JP 11-340516 A JP-A-8-36175

  However, in the display devices described in Patent Documents 1 to 3, each phosphor usually has different afterglow characteristics. Here, afterglow refers to fluorescence emitted from a phosphor for a predetermined time even after irradiation of excitation light is stopped, and afterglow characteristics refer to the length of time during which afterglow is emitted. . Therefore, when phosphors having different afterglow characteristics are used in combination, a certain color may fluoresce for a longer time than other colors after the excitation light irradiation is stopped. For this reason, when a display device using a conventional phosphor is used for a television or the like that displays a fast moving image, a specific color may be emphasized in the displayed image.

Further, as described in Patent Document 4, if the luminance of a pixel is adjusted by adjusting the amount of fluorescence using a liquid crystal cell or the like, a specific color is emphasized as described above. However, the luminous efficiency of the display device, specifically, the luminous efficiency of light emitted from the pixels of the display device was not sufficient.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a display device using fluorescence, which can prevent image deterioration due to afterglow and improve the light emission efficiency. .

  The inventors of the present invention have intensively studied to solve the above-mentioned problems. As a result, the fact that the excitation light corresponding to the black matrix is not used for the light emission of the phosphor may reduce the light emission efficiency of the display device. The knowledge that it is a cause was acquired. For example, as in the technique described in Patent Document 4, in a display device, a black member called a black matrix may be provided between the phosphor portions in order to display black. However, the excitation light applied to the black matrix is absorbed as it is by the black matrix and is not absorbed by the phosphor. Therefore, energy corresponding to the amount of excitation light absorbed by the black matrix is lost without being used for light emission of the phosphor.

  Based on the above knowledge, the inventors of the present invention have developed a phosphor part containing a phosphor that absorbs excitation light and emits visible light, and the visible light emitted from the phosphor contained in the phosphor part. A display device including an optical shutter that adjusts the amount of light and a light source that is provided corresponding to the phosphor portion and emits excitation light of the phosphor toward the phosphor portion. The inventors have found that image deterioration can be prevented and light emission efficiency can be improved, and the present invention has been completed.

  That is, the gist of the present invention is that a phosphor part containing a phosphor that absorbs excitation light and emits visible light, and a phosphor provided in front of the phosphor part and contained in the phosphor part. An optical shutter that adjusts the amount of the emitted visible light and transmits it forward, and a light source that is provided corresponding to the phosphor part and emits excitation light of the phosphor toward the phosphor part. The present invention resides in a display device (claim 1). As a result, image deterioration due to afterglow can be prevented, and light emission efficiency can be improved.

  In this case, the light sources are preferably arranged in an array (Claim 2).

  As the optical shutter, it is preferable to use a liquid crystal optical shutter.

  According to the present invention, it is possible to prevent image deterioration due to afterglow and improve luminous efficiency in a display device using fluorescence.

  Hereinafter, the present invention will be described in detail with reference to embodiments. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified without departing from the gist of the present invention. .

FIG. 1 is a schematic diagram showing the structure of the main part of a color display (hereinafter, simply referred to as “display device”) as an embodiment of the present invention.
As shown in FIG. 1, the display device 1 according to the present embodiment is provided in front of the phosphor portions 2R and 2G containing phosphors that absorb excitation light and emit visible light, and the phosphor portions 2R and 2G. The optical shutter 3 transmits the visible light emitted from the phosphors contained in the phosphor parts 2R and 2G to the front by adjusting the amount of light, and is provided corresponding to the phosphor parts 2R and 2G. And a light source 4 that emits phosphor excitation light toward the body parts 2R and 2G. Here, “front” refers to a direction in which an observer who views an image displayed on the display device 1 is present. Therefore, the direction in which the optical shutter 3 is installed is forward with respect to the phosphor portions 2R and 2G.

Furthermore, when only the fluorescence is used as the light of the pixel of the display device 1, it is desirable that the portion indicated by reference numeral 2B in FIG. However, in the present embodiment, in order to use the light emitted from the light source 4 as a part of the light of the pixel, the display device 1 is configured to include the light transmission portion 2B at a portion indicated by reference numeral 2B. It shall be.
In the display device 1, the light source 4 is provided on the substrate 5. Furthermore, the display device 1 is appropriately provided with a lens array 6, a polarizer 7, an analyzer 8, and the like.

[1. substrate]
The board | substrate 5 is a base holding the light source 4, The shape is arbitrary.
The material of the substrate 5 is also arbitrary, and for example, an appropriate material such as an inorganic material such as a metal, an alloy, glass, or carbon, or an organic material such as a synthetic resin can be used.
However, from the viewpoint of effectively using the excitation light emitted from the light source 4 and improving the light emission efficiency of the display device 1, the surface of the substrate 5 on which the excitation light emitted from the light source 4 hits is reflected on the surface of the substrate 5. The rate is preferably increased. Therefore, it is preferable that at least the surface that is exposed to light is formed of a material having high reflectance. Specific examples include forming the entire substrate 5 or the surface of the substrate 5 with a material (such as an injection shaping resin) containing a material having a high reflectance such as glass fiber, alumina powder, titania powder and the like.

In addition, the specific method for increasing the reflectance of the surface of the substrate 5 is arbitrary. In addition to selecting the material of the substrate 5 itself as described above, for example, a metal having a high reflectance such as silver, platinum, aluminum, The light reflectance can be increased by plating or vapor deposition with an alloy.
The part that increases the reflectivity may be the whole or a part of the substrate 5, but usually the reflectivity of the entire surface of the part that is irradiated with the excitation light emitted from the light source 4 is increased. It is desirable.

  Further, normally, the substrate 5 is provided with electrodes, terminals and the like for supplying power to the light source 4. At this time, the means for connecting the electrode or terminal and the light source 4 is arbitrary. For example, the light source 4 and the electrode or terminal can be connected by wire bonding to supply power. There is no restriction | limiting in the wire to be used, A raw material, a dimension, etc. are arbitrary. For example, a metal such as gold or aluminum can be used as the material of the wire, and the thickness can be usually 20 μm to 40 μm, but the wire is not limited to this.

Another example of a method for supplying power to the light source 4 is a method for supplying power to the light source 4 by flip chip mounting using bumps.
Further, when power is supplied to the light source 4, solder may be used. This is because the solder exhibits excellent heat dissipation, and therefore, when a large current type LED or laser diode, for which heat dissipation is important, is used as the light source 4, the heat dissipation of the display device 1 can be improved. . The type of solder is arbitrary, but, for example, AuSn, AgSn, or the like can be used.

Further, in addition to being connected to electrodes and terminals and used as a power supply path, solder may be used simply for installing the light source 4 on the substrate.
Further, when the light source 4 is attached to the substrate 5 by means other than solder, for example, an adhesive such as an epoxy resin, an imide resin, or an acrylic resin may be used. In this case, by using a paste in which conductive fillers such as silver particles and carbon particles are mixed into the adhesive, the adhesive can be energized to supply power to the light source 4 as in the case of using solder. It is also possible to do so. Furthermore, it is preferable to mix these conductive fillers because heat dissipation is improved.

  In the present embodiment, it is assumed that a flat substrate 5 having a high surface reflectance is used, and a terminal (not shown) for supplying power to the light source 4 is provided on the surface. In addition, it is assumed that power is supplied to the terminal from a power source (not shown).

[2. light source]
The light source 4 emits excitation light for exciting the phosphors contained in the phosphor parts 2R and 2G toward the phosphor parts 2R and 2G. Furthermore, when the observer of the display device 1 can see the light itself emitted from the light source 4, the light emitted from the light source 4 is also the light emitted from the pixels. In the present embodiment, the light source 4 emits light even toward the light transmission portion 2B, and the light emitted from the light source 4 is emitted to the outside of the display device 1 as pixel light through the light transmission portion 2B. Yes.

  However, in the present embodiment, the light sources 4 are provided on a one-to-one basis for each phosphor portion 2R, 2G, corresponding to at least each phosphor portion 2R, 2G. Furthermore, the light sources 4 are provided on a one-to-one basis for each light transmission portion 2B corresponding to the light transmission portion 2B. Thereby, the display apparatus 1 of this embodiment can improve luminous efficiency conventionally.

  That is, when a common light source is provided for each of the phosphor portions 2R, 2G and the light transmission portion 2B, a member between each of the phosphor portions 2R, 2G and the light transmission portion 2B, specifically, black Excitation light is absorbed by the matrix, a base member for holding the phosphor portions 2R and 2G, and the light transmission portion 2B, and the like, and excitation light that is not used for light emission of the phosphor is generated. However, if the light source 4 is provided corresponding to each phosphor part 2R, 2G and the light transmission part 2B as in the present embodiment, the excitation light emitted from the light source 4 can be more efficiently transmitted to each phosphor part 2R, 2G, Since it is possible to irradiate the light transmitting portion 2B, it is possible to increase the proportion of the light emitted from the light source 4 that is absorbed by the phosphor and used for excitation, and is displayed through the light transmitting portion 2B. Since the ratio of light emitted to the outside of the device 1 can be increased, the light emission efficiency of the display device 1 can be improved.

  In this regard, it is desirable to use a light source 4 that can irradiate the corresponding phosphor portions 2R and 2G and the light transmitting portion 2B with excitation light more efficiently. Therefore, among the light sources 4 exemplified later, it is desirable to use a light source with better convergence.

  Furthermore, the wavelength of the excitation light emitted from the light source 4 is arbitrary as long as the phosphor to be used can be excited. When the desirable range of the wavelength of the excitation light is given, the main emission peak wavelength is usually 360 nm or more, preferably 380 nm or more, and usually 500 nm or less, preferably 490 nm or less, more preferably 480 nm or less. If the lower limit of this range is not reached, there is a risk that the photodegradation of the phosphor parts 2R, 2G will become severe. If the upper limit is exceeded, color reproducibility (especially blue color reproducibility) may be reduced.

  When the wavelength of the excitation light emitted from the light source 4 is in the visible region, the excitation light emitted from the light source 4 may be used as it is for displaying an image. In this case, the luminance of the pixel using the light emitted from the light source 4 is adjusted by the optical shutter 3 adjusting the amount of light emitted from the light source 4. For example, when the light source 4 emits blue light having a wavelength of 450 nm to 480 nm, the blue light can be used as light emitted from the pixels of the display device 1 as it is. However, in this case, since it is not necessary to perform wavelength conversion using a phosphor, there is no need for a phosphor portion corresponding to the blue pixel. In this case, in order to match the blue light distribution characteristic with other colors, it is preferable to include light scattering particles in the phosphor portion. As will be described later, in the present embodiment, the light transmission part 2B contains a diffusing agent as light scattering particles, and the fluorescence emitted from the phosphor parts 2R and 2G and the light emitted through the light transmission part 2B The orientation characteristics are matched.

  Examples of the light source 4 include an LED, an edge-emitting or surface-emitting laser diode (hereinafter referred to as “LD” as appropriate), an electroluminescence element, and the like. Of these, an inexpensive LED is usually preferred. Moreover, LED is excellent also in the point which can irradiate light to the fluorescent substance part 2R, 2G and the light transmissive part 2B which correspond efficiently over a long period of time.

Hereinafter, a specific configuration of an LED that can be used as the light source 4 will be described with an example. However, this invention is not limited to the following examples, A well-known thing can be used arbitrarily.
As the light source 4, for example, a ridge type LED 100 shown in FIG. 2 can be used. FIG. 2 is a cross-sectional view schematically showing a main configuration of an example of an LED that can be used in the display device 1 of the present embodiment.

  As shown in FIG. 2, the LED 100 includes a substrate 101 and a buffer layer 102 formed thereon. A first conductivity type first ohmic layer 103 is formed on the buffer layer 102, and a first conductivity type first cladding layer 104 is formed on the first ohmic layer 103. Is provided. An active layer 105 including one or more quantum wells is provided on the cladding layer 104, and a second conductivity type second cladding layer 106 is provided on the active layer 105. Furthermore, a second ohmic layer 107 is provided on the second cladding layer 106 and defines the light emitting surface, ie, the light emitting region of the LED 100.

  In the LED 100, the first electrode 108 is formed on the second ohmic layer 107. The first electrode 108 is patterned so as to surround the light emitting region without being completely covered, or an optically transparent material (for example, ITO) is used so that emitted light (excitation light) can pass through it. It is preferable to do. Further, the second electrode 109 is provided on the back surface of the substrate 101 or on the top surface as shown in FIG. In the example of FIG. 2, the substrate 101 is semi-insalating, and a part of the layers 103, 104, and 105 is etched or removed, and the second electrode 109 is in contact with the first ohmic layer 103. It is assumed that In this example, the first electrode 108 is a p-type contact, and the second electrode 109 is an n-type contact on the opposite side of the diode. As is well known, the LED 100 activates the active layer 105 which is an active region by flowing an appropriate current between the first electrode 108 and the second electrode 109, and emits light in the upper surface of the second ohmic layer 107. Light of a specific wavelength (excitation light) can be emitted through the region.

  When manufacturing this LED 100, the substrate 101 and the various layers 102 to 109 formed thereon are usually formed so as to have a relatively large area, such as a semiconductor wafer. On top of this, typically several thousand or more LEDs are formed in a predetermined arrangement, so that the layers 106, 107 are etched or the material is removed to replace each LED 100 in one or more arrays with another LED 100. It is possible to obtain the LEDs 100 that are separated from each other and arranged in an array.

  In the LED 100 shown here, the entire substrate 101 is made of silicon carbide (SiC), sapphire, or lead oxide (ZnO). The buffer layer 102 is formed of low temperature aluminum nitride (AlN) or gallium nitride (GaN). The first ohmic layer 103 is made of n-type GaN, and the first cladding layer 104 is made of n-type aluminum gallium nitride (AlGaN). The active layer 105 is formed of indium gallium nitride aluminum (InGaAlN) and includes several quantum wells. The second cladding layer 106 is made of p-type AlGaN, and the second ohmic layer 107 is made of p-type GaN. The various layers 102 to 107 can be formed by epitaxial growth on the substrate 101 using an epitaxial technique such as a known MOCVD (metal organic chemical vapor deposition method). The LED 100 emits light (blue) having a wavelength of about 450 nm. This emission wavelength can be somewhat increased or decreased using a band gap mechanism, and an emission wavelength in the range of about 380 nm to 520 nm can be obtained.

  Moreover, as the light source 4, LED110 shown in FIG. 3 can be used, for example. FIG. 3 is a cross-sectional view schematically showing a main configuration of an example of an LED that can be used in the display device 1 of the present embodiment. Also, in FIG. 3, parts indicated by the same reference numerals as those in FIG. 2 are the same as those in FIG.

  The LED 110 shown in FIG. 3 is generally called a planar type LED. In this type, the separation between adjacent LEDs 110 on the chip is driven by a high resistance or opposite conductive region (high resistance region) 111 into the upper layer (here, active layer 106 and second ohmic layer 107). Is achieved. The high resistance region 111 formed in a ring shape as a whole restricts the current flow in the central region in the region 111 and effectively separates the central portion from all surrounding materials. The advantage of this type of LED 110 is that the top surface is planar and can be used to easily support the structure added thereon without adding a step of providing a planarization layer. It is.

  Since the light emitted from the LED 110 is usually Lambertian light distribution (that is, usually emitted in a hemispherical form), a light separation unit that prevents or reduces crosstalk of light between adjacent LEDs 110 may be provided. As shown in FIG. 4, an example of a method for providing a light separating portion is to form a raised portion 112 on the upper surface of a chip or wafer so as to surround the light emitting region of each LED 110 and to direct light in a desired direction. Is to form. In some cases, the raised portion 112 can be formed of a light absorbing material to further prevent or reduce reflection and resulting crosstalk. For example, when the LED 110 emits red light, the ridge 112 is preferably formed of germanium that absorbs red light. FIG. 4 is a cross-sectional view schematically showing a main configuration of an example of an LED that can be used in the display device 1 of the present embodiment. Further, in FIG. 4, parts indicated by the same reference numerals as those in FIGS. 2 and 3 are the same as those in FIGS.

  By the way, the light sources 4 are preferably arranged in an array. That is, it is preferable that the light sources 4 are arranged in rows and columns as a whole so that the regions on which images can be formed can be individually specified. Accordingly, the phosphor portions 2R and 2G can be arranged in an array, and a full color image can be appropriately formed on the display device 1.

Typically, to form a full color image, each pixel of the image includes three types of pixel regions corresponding to one of the three primary colors (ie, red, green, and blue). Note that substantially all colors can be obtained even if some changes are made to the colors or only two colors are used depending on the application. If the light sources 4 are arranged in an array, these three primary colors can be appropriately arranged, and thereby a full color image can be displayed.
Also, the electrical connections to the various light sources 4 usually determine the exact function of the display device 1 and the pixel arrangement.

Furthermore, when installing the light source 4 on the board | substrate 5, there is no restriction | limiting in the installation means, Well-known arbitrary means can be used. Therefore, as described above, for example, the light source 4 can be installed on the substrate 5 using solder or the like.
Further, as shown in FIG. 5, the light source 4 can also be disposed on the substrate 5 via a mounting substrate (supporting substrate) 113. Here, FIG. 5 is a cross-sectional view schematically showing an enlarged main part of a portion where the light source 4 is installed on the substrate 5. In FIG. 5, parts indicated by the same reference numerals as those in FIGS. 1 to 4 are the same as those in FIGS. 1 to 4.

  When the light source 4 is installed on the substrate 5 as shown in FIG. 5, for example, a silicon integrated circuit (IC; not shown) in which a drive circuit or the like is formed may be formed on the substrate 5. Further, the mounting substrate 113 may be formed with an interconnection circuit. In this case, the light source 4 can be connected to the integrated circuit of the substrate 5 by the interconnection circuit. Further, using a plurality of C4 type bumps or epoxy adhesive 114, a transparent substrate 201 (described later) provided with phosphor portions 2R and 2G is mounted side by side on the substrate 5, and they are attached by a diode array. You may make it irradiate. The bumps 114 are shown at the edge of the transparent substrate 201. However, depending on the application, it is more convenient to form a higher raised portion 112 (see FIG. 4) or to place mounting bumps thereon. .

  In the present embodiment, the light source 4 is the same as the LED 110 that emits blue light. Further, the light sources 4 are arranged in an array on the substrate 5, and each light source 4 is provided corresponding to each pixel. That is, the light source 4 is provided corresponding to the phosphor portions 2R and 2G and the light transmission portion 2B. Further, it is assumed that the power supply to the light source 4 is performed by electrically connecting the terminals on the substrate 5 and the electrodes of the light source 4 using an interconnection circuit, wires, or the like.

  By the way, in this embodiment, the light transmission part 2B is provided and the blue light emitted from the light source 4 is used as a part of the light of the pixel. However, as the light source 4, for example, light outside the visible region of ultraviolet to near ultraviolet is used. When used, the light from the light source 4 is usually not used as pixel light. In such a case, normally, a phosphor (for example, a blue phosphor) is included in the light transmitting portion 2B, and a phosphor portion (see FIG. 9) corresponding to the position of the light transmitting portion 2B is provided. It will be.

[3. Phosphor part]
The phosphor portions 2R and 2G are provided corresponding to each predetermined pixel, and include a phosphor that absorbs excitation light emitted from the light source 4 and emits visible light for forming an image displayed on the display device 1. It is a part which produces the light which the pixel of the display apparatus 1 emits.
Similarly to the phosphor portions 2R and 2G, the light transmission portion 2B provided for each predetermined pixel is a portion for using the light from the light source 4 as part of the light of the pixel. Usually, the light transmission portion 2B is provided in the same manner as the phosphor portions 2R and 2G except that it does not contain the phosphor.

There is no restriction | limiting in the fluorescent substance used in this embodiment, Arbitrary fluorescent substance can be used unless the effect of this invention is impaired remarkably.
Phosphors can emit very bright light and a great variety of colors of fluorescence. However, in order to excite the phosphor, high energy electrons or high energy photons must collide with the phosphor. For example, a cathode ray tube (CRT) of a full color display has been conventionally used to excite a phosphor, but an electron having sufficient energy to excite the phosphor on a CRT faceplate. Large amounts of power and high voltage were required to generate the current.

  Conventionally, some suggestions have been made to replace an electron gun in a CRT with a semiconductor laser. However, known prior art LDs (including LEDs) all have sufficient energy to excite phosphors. Is not necessarily generated. In contrast, because the GaN LEDs described above have high efficiency, and because of the wavelength of the emitted light, the emitted photons (light) are sufficiently high in energy and quantity to excite the phosphor. Have As a specific example, as shown in the graph of FIG. 6, a typical phosphor absorbs a photon including a photon having a wavelength λ of 450 nm (curve α) and emits a photon having a different wavelength (curve β). . The phosphor shown in FIG. 6 is a green phosphor, which absorbs 450 nm wavelength λ photons (blue light) and emits 550 nm photons (green light). Typically, the conversion rate is 50% to 100%. The vertical axis of the graph of FIG. 6 represents a value (I) obtained by standardizing the intensity of absorbed light and emitted light with the maximum intensity of each of the curves α and β in this wavelength region.

  Further, in the present embodiment, the phosphor is used by blending one type or two or more types of phosphors. The emission color of the phosphor is not particularly limited because there is an appropriate color depending on the application, but blue, green, and red phosphors with high color purity are preferably used when, for example, a full color display is manufactured. There are several methods for expressing the appropriate color. For convenience, the center wavelength of light emission, CIE chromaticity coordinates, and the like are used. In addition, when the light wavelength conversion mechanism is monochrome display or multicolor display, it is preferable to include a phosphor that develops purple, blue-violet, yellow-green, yellow, or orange. Further, two or more of these phosphors may be mixed to emit light with high color purity, or to emit intermediate color or white light.

Speaking of the central wavelength of light emission, for example, a specific wavelength range of fluorescence emitted by a phosphor emitting red fluorescence (hereinafter referred to as “red phosphor” as appropriate) is illustrated. The central wavelength is usually 370 nm or more, Preferably it is 380 nm or more, and usually 500 nm or less, preferably 480 nm or less.
Further, for example, when a specific wavelength range of fluorescence emitted by a phosphor emitting green fluorescence (hereinafter referred to as “green phosphor” as appropriate) is exemplified, the center wavelength is usually 490 nm or more, preferably 500 nm or more, Usually, it is 570 nm or less, preferably 550 nm or less.
Furthermore, for example, when a specific wavelength range of fluorescence emitted by a phosphor emitting blue fluorescence (hereinafter referred to as “blue phosphor” as appropriate) is exemplified, the center wavelength is usually 420 nm or more, preferably 440 nm or more, Usually, it is 480 nm or less, preferably 470 nm or less.

The composition of the phosphor is not particularly limited, but a metal oxide represented by Y ₂ O ₃ , Zn ₂ SiO _4, etc., which is a crystal matrix, phosphorus represented by Ca ₅ (PO ₄ ) ₃ Cl, etc. Acids and sulfides represented by ZnS, SrS, CaS, etc., ions of rare earth metals such as Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Ag A combination of metal ions such as Al, Mn, and Sb as an activator or coactivator is preferable.

Preferred examples of the crystal matrix include, for example, ZnS, Y ₂ O ₂ S, (Y, Gd) ₃ Al ₅ O ₁₂ , YAlO ₃ , BaAl ₂ Si ₂ O ₈ , Y ₃ Al ₅ O ₁₂ , Y ₂ SiO _5. , Zn ₂ SiO ₄ , Y ₂ O ₃ , BaMgAl ₁₀ O ₁₇ , BaAl ₁₂ O ₁₉ , (Ba, Sr, Mg) O · αAl ₂ O ₃ , (Y, Gd) BO ₃ , Y ₂ O ₃ , (Zn , Cd) S, SrGa ₂ S ₄ , SrS, SnO ₂ , Ca ₁₀ (PO ₄ ) ₆ (F, Cl) ₂ , (Ba, Sr) (Mg, Mn) Al ₁₀ O ₁₇ , (Sr, Ca, Ba) , Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ , (La, Ce) PO ₄ , CeMgAl ₁₁ O ₁₉ , GdMgB ₅ O ₁₀ , Sr ₂ P ₂ O ₇ , Sr ₄ Al ₁₄ O ₂₅ , (Ba, Sr, Ca ) (Mg, Zn, can be mentioned Mn) Al ₁₀ O _17.

  However, the above-mentioned crystal matrix and activator or coactivator are not particularly limited in elemental composition, and can be partially replaced with elements of the same family, and the obtained phosphor absorbs ultraviolet rays and emits visible light. Those are preferred. Examples of phosphors that can be used are given below. However, the phosphors used in the display device 1 of the present embodiment are not limited to those exemplified below.

・ Red phosphor:
The red phosphor capable of emitting red light by ultraviolet irradiation is composed of, for example, broken particles having a red fracture surface and emits light in the red region (Mg, Ca, Sr, Ba) ₂ Si ₅ N ₈ : Eu. The europium-activated alkaline earth silicon nitride-based phosphor represented, which is composed of growing particles having a substantially spherical shape as a regular crystal growth shape, emits light in the red region (Y, La, Gd, Lu) ₂ O ₂ Examples include europium-activated rare earth oxychalugenite-based phosphors represented by S: Eu.

  Furthermore, the oxynitride and / or acid containing at least one element selected from the group consisting of Ti, Zr, Hf, Nb, Ta, W, and Mo described in JP-A-2004-300247 A phosphor containing a sulfide and containing an oxynitride having an alpha sialon structure in which a part or all of the Al element is substituted with a Ga element can also be used in this embodiment. These are phosphors containing oxynitride and / or oxysulfide.

Other red phosphors include Y ₂ O ₂ S: Eu ³⁺ , (BaMg) ₂ SiO ₄ : Eu ³⁺ , (BaCaMg) ₅ (PO ₄ ) ₃ Cl: Eu ³⁺ , YVO ₄ : Eu. ³⁺ , CaS: Eu ³⁺ , YAlO ₃ : Eu ³⁺ , Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Eu ³⁺ , LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺ , (Y, Gd _{) 3 Al 5 O 12: Ce} 3+, (Ca, Sr) 2 Si 5 N 8: Eu, CaSiN 2: Eu, CaAlSiN 3; Eu, (Sr, Ca, Ba, Mg) 10 (PO 4) 6 Cl ₂ : Eu, Mn, (Ba ₃ Mg) Si ₂ O ₈ : Eu, Mn, etc. can also be used.

・ Green phosphor:
As a green phosphor capable of emitting green light by ultraviolet irradiation, for example, it is composed of fractured particles having a fracture surface, and emits light in a green region (Mg, Ca, Sr, Ba) represented by Si ₂ O ₂ N ₂ : Eu. Europium-activated alkaline earth silicon oxynitride-based phosphors, europium-activated alkaline earths represented by (Ba, Ca, Sr) ₂ SiO ₄ : Eu that are composed of fractured particles having a fracture surface Examples include magnesium silicate phosphors.

In addition, as the green phosphor, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ , Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ , (SrBa) Al ₂ Si ₂ O ₈ : Eu ²⁺ , (BaMg) ) ₂ SiO ₄ : Eu ²⁺ , Y ₂ SiO ₅ : Ce ³⁺ , Tb ³⁺ , Sr ₂ P ₂ O ₇ —Sr ₂ B ₂ O ₅ : Eu ²⁺ , (BaCaMg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ , Sr ₂ Si ₃ O ₈ -2SrCl ₂ : Eu ²⁺ , Zr ₂ SiO ₄ , MgAl ₁₁ O ₁₉ : Ce ³⁺ , Tb ³⁺ , Ba ₂ SiO ₄ : Eu ²⁺ , Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Tb ³⁺ , Y ₃ Al ₅ O ₁₂ : Tb ³⁺ , La ₃ Ga ₅ SiO ₁₄ : Tb ³⁺ , SrGa ₂ S ₄ : Eu ²⁺ , Tb ³⁺ , Sm ^{2 _{+, Y 3 (Al, Ga}} ) 5 O 12: Ce, Ca 3 Sc 2 Si 3 O 12: Ce, SrSi 2 O 2 N 2: Eu, BaMgAl 10 O 17: Eu, M , SrAl ₂ O _4: Eu can also be used like.

・ Blue phosphor:
As a blue phosphor capable of emitting blue light by ultraviolet irradiation, europium activated barium represented by BaMgAl ₁₀ O ₁₇ : Eu, which is composed of growing particles having a substantially hexagonal shape as a regular crystal growth shape, and emits light in a blue region. Magnesium aluminate-based phosphor, which is composed of growing particles having a substantially spherical shape as a regular crystal growth shape, emits light in the blue region, and is represented by (Ca, Sr, Ba) ₅ (PO ₄ ) ₃ Cl: Eu Europium-activated calcium halophosphate-based phosphor, which is composed of grown particles having a cubic shape as a regular crystal growth shape, and emits light in the blue region (Ca, Sr, Ba) ₂ B ₅ O ₉ Cl: Eu Europium activated alkaline earth chloroborate phosphor, composed of fractured particles with fractured surface, blue green Performing emission band (Sr, Ca, Ba) Al 2 O 4: Eu or _{(Sr, Ca, Ba) 4} Al 14 O 25: europium-activated alkaline earth aluminate phosphors represented by Eu, and the like .

In addition, blue phosphors include Sr ₂ P ₂ O ₇ : Sn ⁴⁺ , Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , SrGa ₂ S ₄ : Ce ³⁺ , CaGa ₂ S ₄ : Ce ³⁺ , (Ba, Sr) (Mg, Mn) Al ₁₀ O ₁₇ : Eu ²⁺ , (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ , BaAl ₂ Si ₂ O ₈ : Eu ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Tb ³⁺ , Sm ²⁺ , (Ba, Sr, Ca) (Mg, Zn, Mn) Al ₁₀ O ₁₇ : Eu ²⁺ (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu, (Ba, Sr) MgAl ₁₀ O ₁₇ : Eu, (Sr, Ba) ₃ MgSi ₂ O ₈ : Eu, etc. may be used. Is possible.

  In addition, the above-mentioned red phosphor, green phosphor, blue phosphor, and the like, which emit fluorescence of the color emitted from each pixel, may be used alone or in combination of two or more in any combination and ratio. You may use together.

  Furthermore, if the phosphor parts 2R and 2G contain the above-described phosphor and can emit visible light having a color corresponding to the pixel of the display device 1, the specific configuration thereof is arbitrary. A binder is used to protect the phosphor from external forces and moisture from the external environment. Specifically, the phosphor portions 2R and 2G are configured by a molded body in which the phosphor is dispersed in a binder.

  Any known binder can be used as the binder, but it is usually preferable to use a colorless and transparent material in order to appropriately transmit fluorescence and excitation light. Specific examples include polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose polystyrene, styrene / maleic anhydride copolymer, styrene / acrylonitrile copolymer, polyvinyl chloride, cellulose acetate. Butyrate, cellulose propionate, poly α-naphthyl methacrylate, polyvinyl naphthalene, poly n-butyl methacrylate, tetrafluoroethylene / hexafluoropropylene copolymer, polycyclohexyl methacrylate, poly (4-methylpentene), epoxy, polysulfone, Polyetherketone, polyarylate, polyimide, polyetherimide, cyclic olefin polymer, Hexane, benzocyclobutane polymers, water glass, silica, titanium oxide, and those with such a component epoxy resin. Among these, a resin having substantially no absorption at 380 nm to 500 nm is preferable, and a non-aromatic epoxy resin is particularly desirable. In addition, a binder may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  Moreover, you may make the fluorescent substance part 2R, 2G contain additives other than a binder and fluorescent substance. As an additive, for example, a diffusing agent may be added to further increase the viewing angle. Specific examples of the diffusing agent include barium titanate, titanium oxide, aluminum oxide, and silicon oxide. In addition, as an additive, for example, an organic or inorganic coloring dye or coloring pigment may be contained for the purpose of cutting an undesired wavelength. In addition, these additives may be used individually by 1 type, respectively, and may use 2 or more types together by arbitrary combinations and ratios.

  Furthermore, the phosphor parts 2R and 2G can be produced by any known method. For example, the phosphor portions 2R and 2G are made of a mixture (coating liquid) composed of a binder, a phosphor and a solvent in a mosaic shape, an array shape, or a stripe shape at intervals corresponding to the pixels of the optical shutter 3 by screen printing. Further, it can be formed on the transparent substrate 21.

  Further, a block matrix layer 22 may be formed between the phosphor portions 2R and 2G for absorbing external light. The black matrix layer 22 may be formed on a transparent substrate 21 such as glass by a process of manufacturing a light absorption film made of carbon black using the photosensitive principle of a photosensitive resin. A mixture composed of a solvent may be laminated by screen printing.

  Moreover, the shape of the phosphor portions 2R and 2G is arbitrary. For example, when the display device 1 is set to multicolor display, phosphors that emit light of a predetermined color are arranged in the light emitting regions such as the phosphor portions 2R and 2G in accordance with the pixel shape of the optical shutter mechanism. However, examples of the shape of the phosphor portions 2R and 2G include a segment shape and a matrix shape necessary for information display. Among the matrix shapes, a stripe structure, a delta structure, and the like can be given as preferable forms. Furthermore, in the case of monochrome display, in addition to the above-described shape, it is possible to apply a uniform light emitter.

  Furthermore, the dimensions of the phosphor portions 2R and 2G are also arbitrary. For example, the thickness is arbitrary as long as the effects of the present invention are not significantly impaired, but usually, it can be suitably used when the thickness is 1 cm or less. Furthermore, in a flat panel display that is required to be thin and light, it is more preferable that the thickness be 2 mm or less. Considering the balance with the emission rate of emitted light, it is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 1000 μm or less, preferably 500 μm or less, more preferably 300 μm or less.

  By the way, when the visible light such as blue light is emitted from the light source 4 as in the present embodiment, the visible light emitted from the light source 4 can be used as the light emitted from the pixels. In that case, a phosphor portion that emits fluorescence of the same color as the light corresponding to the visible light is not essential. For example, when a blue light emitting LED is used as the light source 4, a phosphor part including a blue phosphor is unnecessary. Therefore, as long as the visible light emitted from the light source 4 is adjusted by the optical shutter and emitted outside the display device 1, it is not always necessary to use phosphors in all the pixels. However, even in that case, visible light emitted from the light source 4 is efficiently added to the binder to visible light emitted from the light source 4 in order to efficiently emit or scatter the visible light to the outside, or to cut off light having an undesired wavelength. It is desirable to transmit the light transmitting portion 2B containing the agent.

  Hereinafter, specific configurations that the phosphor portions 2R and 2G and the light transmission portion 2B can take will be described with reference to FIG. However, this invention is not limited to the following examples, A well-known thing can be used arbitrarily.

  FIG. 7 is a cross-sectional view schematically showing an example of a configuration that the phosphor portions 2R and 2G and the light transmission portion 2B can take. In FIG. 7, one phosphor portion 2R, 2G and one light transmission portion 2B are shown. Normally, in the display device 1, these phosphor portions 2R, 2G and light transmission portion 2B are arranged in an array. Two or more are arranged. Moreover, in FIG. 7, the site | part shown using the code | symbol similar to FIGS. 1-6 shows the same thing as FIGS.

  In this example, the LEDs 110R, 110G, and 110B are each configured to emit blue light. Further, the phosphor portion 2R includes a red phosphor, and the phosphor portion 2R emits red light when irradiated with light from the LED 110R. Further, the phosphor portion 2G includes a green phosphor, and the phosphor portion 2G emits green light when irradiated with light from the LED 110G. Further, the individual area 201B of the plate 201 remains simply transparent so that the blue light emitted by the LED 110B can pass directly, and the individual area 201B does not perform wavelength conversion on the light emitted by the LED 110B. 1) to function as a light transmitting portion 2B that emits the light toward the screen. Accordingly, the phosphor portion 2R emits red light through the region 201R corresponding to the red pixel, the phosphor portion 2G emits green light through the region 201G corresponding to the green pixel, and the LED 110B corresponds to the blue pixel. Thus, blue light can be emitted through the region 201B (that is, the light transmitting portion 2B). In this case, wavelength conversion, that is, secondary emission is not required to generate blue light. Depending on the application, the LEDs 110R and 110G are made slightly larger than the LED 110B, and finally emitted from the upper surface of the plate 201. It is also convenient to make the amount of light to be substantially the same in each of the regions 201R, 201G, and 201B.

  In the example shown in FIG. 7, LEDs 110R, 110G, and 110B corresponding to the phosphor portions 2R and 2G and the light transmitting portion 2B are formed on the substrate 101, respectively. In these LEDs 110R, 110G, and 110B, the buffer layer 102 is formed as a part thereof (or as an additional layer on the buffer layer 102 depending on the application). Further, as described with reference to FIG. An ohmic layer 103, a first cladding layer 104, an active region 105, a second cladding layer 106, and a second ohmic layer 107 are continuously formed thereon. Further, a high resistance region 111 is formed by injection into the second ohmic layer 107, separating the LEDs 110R, 110G, and 110B from each other and from other LEDs in the array. In addition, the raised portion 112 is formed by laminating a material layer on the upper surface of the second ohmic layer 107 and patterning the material layer. Note that the raised portion 112 acts so that the light is directed outward (upward in FIG. 8) and does not advance toward the adjacent LED.

  A plate 201 is provided in parallel to the substrate 101 at a position away from the LED array in which the LEDs 110R, 110G, and 110B are arranged as a whole. The plate 201 is provided with a plurality of individual areas 201R, 201G, and 201G. Here, the plate 201 is formed of an optically transparent material such as glass, plastic, crystal, or the like. Furthermore, the arrangement of the plate 201 is such that light emitted from each LED of the LED array, specifically in this example, the LEDs 110R, 110G, and 110B (see the arrows in FIG. 8) is a plurality of individual regions 201R and 201G of the plate 201. , 201G are set so as to enter each different one. Furthermore, the phosphor parts 2R and 2G containing different phosphors are respectively attached to different areas of the individual areas 201R and 201G of the plate 201, and are installed so as to be irradiated with light from the LEDs 110R and 110G, respectively. When the phosphor portions 2R and 2G are irradiated with light from the LEDs 110R and 110G, the phosphors contained therein absorb the light and emit different fluorescent colors.

  Another different embodiment is shown in FIG. FIG. 8 is a cross-sectional view schematically showing an example of the configuration that the phosphor portions 2R and 2G can take. Also in FIG. 8, one phosphor portion 2R and 2G is shown, but usually two or more of these phosphor portions 2R and 2G are arranged in an array in the display device 1, respectively. Moreover, in FIG. 8, the part shown using the code | symbol similar to FIGS. 1-7 shows the same thing as FIGS.

  Here, the plate 201 provided in FIG. 7 is simply removed, and the phosphor portions 2R and 2G are directly arranged on the surfaces of the LEDs 110R and 110G. However, the phosphor portion is not provided on the surface of the LED 110B for emitting blue light. Further, the remaining elements are basically the same as those described in relation to FIG. Accordingly, the phosphor portion 2R emits red light corresponding to the red pixel, the phosphor portion 2G emits green light corresponding to the green pixel, and the LED 110B emits blue light corresponding to the blue pixel. Can be done. Further, according to the configuration of this example, in addition to the advantage obtained by the configuration described with reference to FIG. 7, there is an advantage that the number of elements can be reduced, and the device can be manufactured more inexpensively and easily.

  By the way, in each of the above examples, the LEDs 110R, 110G, and 110B, the phosphor portions 2R, 2G, and the light transmitting portion 2B can individually designate areas to form an image via the optical shutter 3 thereon. Thus, it is preferable that they are arranged in an array that is generally arranged in rows and columns. In order to form a full-color image, each pixel of the image preferably includes three LED regions corresponding to one of the three primary colors (ie, red, green, and blue). Of course, it is understood that substantially all colors can be obtained even if the color is slightly changed or only two colors are used in some applications.

  Moreover, in the example shown using said FIG.7 and FIG.8, although LED110B which is the light source 4 emitted blue light, the example which uses the light which LED110B emits as a blue pixel light was shown. Those emitting light other than visible light such as ultraviolet light to near ultraviolet light can also be used. In this case, if a phosphor part including a blue phosphor that emits blue light by absorbing light other than visible light is provided on the regions 201B and 202B in FIG. 7 and the LED 110B in FIG. As in the case of using the light source 4 that emits light, a full-color display device having red, green, and blue pixels can be obtained.

  In this embodiment, as shown in FIG. 1, the phosphor portion 2R in which the red phosphor is dispersed in the binder corresponding to the red pixel, and the green phosphor is dispersed in the binder corresponding to the green pixel. It is assumed that the light transmitting portion 2B in which a diffusing agent is dispersed in a binder corresponding to the phosphor portion 2G and the blue pixel is provided on the transparent substrate 21 in an array corresponding to the light source 4, respectively. As the binder, a binder that can transmit red light, green light, and blue light is used. As a result, the phosphor portion 2R receives light from the light source 4 and emits red light to the optical shutter 3 to thereby emit the phosphor portion 2G. Receives light from the light source 4 and emits green light to the optical shutter 3. Further, the blue light emitted from the light source 4 corresponding to the light transmission part 2B is diffused by the diffusing agent when transmitted through the light transmission part 2B, and is emitted to the optical shutter 3. Further, it is assumed that the phosphor parts 2R and 2G and the light transmission part 2B are partitioned by the black matrix 22, respectively.

[4. Lens array]
The red light and green light emitted from the phosphor parts 2R and 2G and the blue light emitted from the light source 4 are effective in front of the phosphor parts 2R and 2G and the light transmitting part 2B (that is, the optical shutter 3 side). In order to utilize, it is preferable to provide a light distribution element. As a specific example, it is preferable to install an optical lens or the like. In this embodiment, a microlens array 6 in which optical lenses are arranged in an array is provided on a substrate, and red light, green light, and blue light are respectively condensed on each pixel portion of the optical shutter 3. Shall.

[5. Polarizer]
A polarizer is appropriately provided on the back side (lower side in FIG. 1) of the optical shutter 3. The polarizer is provided in order to align the plane of polarization. In the present embodiment, it is assumed that a polarizer 7 that transmits only an arbitrary linearly polarized light component of light irradiated by the optical shutter 3 is disposed between the microlens array 6 and the optical shutter 3. When a TFT (Thin Film Transistor), STN (Super Twisted Nematic Liquid Crystal), or the like is used as an optical shutter, the polarizer 7 is essential because the TFT and STN are elements that change the polarization plane of light. It becomes. However, this is not necessary when using a PDN (Polymer Dispersed Network) type optical shutter or the like.

[6. Light shutter]
The display device 1 of the present embodiment includes an optical shutter 3 in front of the phosphor portions 2R and 2G and the light transmission portion 2B. The optical shutter 3 is a member that transmits the visible light emitted from the phosphors contained in the phosphor parts 2R and 2G forward by adjusting the light amount. Further, in the case where light (blue light or the like) emitted from the light source 4 is used as it is as pixel light as in the present embodiment, not only visible light emitted from the phosphor but also light emitted from the light source 4 is used. The light quantity is adjusted so that the light is transmitted forward.

  The mechanism of the optical shutter 3 is usually composed of an assembly of a plurality of pixels (pixels). In this display device 1, each part of the optical shutter 3 that transmits light from the light source 4 that has passed through the light transmission part 2 </ b> B and light emitted from the phosphor parts 2 </ b> R and 2 </ b> G controls each pixel of the display device 1. The brightness is adjusted for each pixel. However, the number and size of pixels and the arrangement method vary depending on the screen size, display method, and application, and are not particularly limited to certain values.

  When the display device 1 is configured as a multi-color or full-color display, the above-described phosphors are arranged in two or more kinds of regions (that is, the phosphor portions 2R and 2G) that are independently defined as the light wavelength conversion mechanism, The amount of light emitted from the area is adjusted by the optical shutter 3 so that a desired image can be displayed on the display device 1 by multicolor light emission. For example, in a matrix-driven display color display that displays images such as graphic display on a notebook computer or television, display required for image display is achieved by adjusting the light emission of the three primary colors of high purity red, blue, and green with the optical shutter 3. An image is formed with colors.

  Furthermore, in the present embodiment, the optical shutter 3 is a light having a light emission center wavelength used by the display device 1, specifically, a light amount of light in a wavelength range of usually 380 nm or more, and usually 780 nm or less, preferably 420 nm or less. It is desirable to be able to adjust.

  Moreover, there is no restriction | limiting in the dimension of the pixel of the optical shutter 3, and it is arbitrary unless the effect of this invention is impaired remarkably. For example, in a normal display application, the size of one pixel is preferably 500 μm square or less. Furthermore, as a suitable pixel size, it is more preferable that the number of pixels is about 640 × 3 × 480 and the single pixel size is about 100 × 300 μm as a value of a liquid crystal display currently in practical use.

  Furthermore, it is preferable that a black region called a black matrix exists between these pixels in order to increase the contrast. The black matrix functions to make the gap between the phosphor portions 2R and 2G and the light transmission portion 2B, that is, the gap between the pixels black, and make the image easy to see. As the material of the black matrix, for example, chromium, carbon, or a resin in which carbon or other black material is dispersed is used, but the material is not limited thereto.

Further, the quantity and size of the optical shutter 3 itself are not limited and are arbitrary as long as the effects of the present invention are not significantly impaired. For example, the thickness of the optical shutter 3 is usually 5 cm or less, and preferably 1 cm or less in consideration of reduction in thickness and weight.
Further, in the case where the display device 1 is a flat display device, a device that can change the light transmittance of the pixel to an arbitrary value by electrical control can be suitably used to enable gradation display. . The higher the absolute value of the light transmittance, the contrast of the change and the speed response, the better.

  Examples of optical shutters 3 that satisfy these requirements include TFT, STN, ferroelectric, antiferroelectric, guest host using dichroic dye, transmissive liquid crystal optical shutter such as polymer dispersed PDN system; oxidation Examples include tungsten, iridium oxide, Prussian blue, viologen derivatives, TTF-polystyrene, rare earth metal-diphthalocyanine complexes, electrochromics typified by polythiophene, polyaniline, and the like. Among them, a liquid crystal optical shutter is preferably used because it is thin, lightweight, and has low power consumption, has practical durability, and can increase the density of segments. Among these, a liquid crystal optical shutter using a TFT active matrix drive or a PDN method is particularly desirable, and a liquid crystal optical shutter driven by a TFT active matrix is particularly desirable. The reason is that the active matrix using twisted nematic liquid crystal does not cause high-speed response and crosstalk corresponding to moving images, and the PDN method does not require the polarizer 7 and the analyzer 8, so the light source 4 and the phosphor portion This is because light from 2R and 2G is less attenuated and can be emitted with high brightness.

  The display device 1 is usually provided with a control unit (not shown) that controls the optical shutter 3 so as to adjust the amount of light according to the image displayed on the display device 1. The optical shutter 3 adjusts the amount of visible light emitted from each pixel in accordance with the control of the control unit, whereby a desired image is displayed on the display device 1.

  By adjusting the luminance of the pixels by the optical shutter 3, the display device 1 can eliminate the influence of the afterglow characteristics of the phosphor, and further simplify the control circuit of the control unit. be able to. In a conventional display device using a phosphor, the luminance of a pixel is adjusted by controlling the light emission intensity of the light source 4. In this case, an image to be displayed is displayed due to the influence of the afterglow characteristics of the phosphor. In certain cases, certain colors were emphasized. In addition, when an LED or the like is used as the light source 4, the light emission intensity of the light source is adjusted by adjusting the current flowing through the light source. However, since the current-luminance characteristics of the LED change with time, the displayed image is controlled. The control circuit was complicated.

In contrast to this, an optical shutter 3 portion for adjusting the amount of light emitted from the phosphor portions 2R and 2G and the light source 4 is provided as in the present embodiment, and afterglow characteristics between pixels are forced by opening and closing the optical shutter 3. Thus, it is possible to prevent only a specific color of the image from being emphasized. Therefore, by using the optical shutter 3, phosphors having different afterglow characteristics can be used for the display device 1.
In addition, since most of the optical shutters 3 such as liquid crystal optical shutters are voltage controlled, the luminance can be adjusted with a simple control circuit by adjusting the light amount and the luminance with the optical shutter 3.

  In the present embodiment, a transparent electrode 31, an alignment film 32, a liquid crystal 33, an alignment film 34, and a transparent electrode 35 are stacked in this order, and a liquid crystal optical shutter in which each pixel is separated by a black matrix 36 is used as the optical shutter 3. It shall be. In this liquid crystal light shutter, the molecular arrangement of the liquid crystal 33 is controlled by the voltage applied to the transparent electrodes 31, 35, and the light quantity of red light, green light and blue light irradiated on the back side is adjusted by this molecular arrangement. It is like that.

[7. Analyzer]
In front of the optical shutter 3, an analyzer 8 that normally receives visible light whose light amount is adjusted through the optical shutter 3 is provided. The analyzer 8 is for transmitting only light having a specific polarization plane that has passed through the optical shutter 3. Similar to the polarizer 7, it is essential when a TFT, STN, or the like is used as the optical shutter 3, but is not necessary when a PDN type optical shutter or the like is used.
Also in this embodiment, it is assumed that an analyzer 8 is provided in front of the optical shutter 3.

[8. Action]
Since the display device 1 of the present embodiment is configured as described above, all the blue light-emitting LEDs that are the light sources 4 emit light with a predetermined intensity when used. The blue light emitted from the light source 4 is incident on the corresponding phosphor portions 2R and 2G and the light transmitting portion 2B, respectively.
In the phosphor portion 2R, the red phosphor dispersed in the phosphor portion 2R absorbs blue light and emits red fluorescence corresponding to the red pixel. In the phosphor portion 2G, the green phosphor dispersed in the phosphor portion 2G absorbs blue light and emits green fluorescence corresponding to the green pixel. Further, in the light transmission part 2B, the diffusing agent dispersed in the light transmission part 2B disperses the blue light and transmits the blue light dispersed corresponding to the blue pixels.

The red and green fluorescence generated in this way, and the blue light dispersed by the light transmission part 2B are respectively collected by the lenses provided in the microlens array 6, and after the polarization plane is aligned by the polarizer 7, The light enters the optical shutter 3.
The optical shutter 3 adjusts the amount of red light, green light, and blue light incident from the back side according to the image to be displayed according to the control of the control unit, and transmits the light forward. Specifically, by controlling the voltage applied to the transparent electrodes 31 and 35, the orientation of the liquid crystal in the portion corresponding to each pixel is adjusted, and thereby, how much light is transmitted per pixel. The light received on the back surface is transmitted forward while adjusting or adjusting.
The light passing through the optical shutter 3 is applied to the analyzer 8. An observer sees the light emitted from the surface of the analyzer 8 and recognizes the image.

By configuring the display device 1 as described above, it is possible to prevent image deterioration due to afterglow and to improve luminous efficiency.
In particular, since the liquid crystal light shutter is used as the light shutter 3, it is not necessary to use a complicated control for adjusting the luminance of the pixels used for image display, and the control can be simplified.

[9. Others]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to said Embodiment, In the range which does not deviate from the summary of this invention, it can change arbitrarily and can implement.
For example, in the above embodiment, the case where an image is displayed using three kinds of light of red, green, and blue has been described. However, the image display is performed using light other than the above red, green, and blue. In addition, image display may be performed using two types or four or more types of light.

Further, for example, similarly to the phosphor portions 2R and 2G, a phosphor portion 2B ′ containing a phosphor emitting blue fluorescence may be provided instead of the light transmitting portion 2B (FIG. 9). However, in this case, a light source 4 that emits light having a wavelength capable of exciting the phosphor in the phosphor portion 2B ′ is used. As a result, the light emitted from the light source 4 is not used as blue pixel light, but the fluorescence emitted from the phosphor in the phosphor portion 2B ′ can be used as blue pixel light. In this case, the configuration of the phosphor portion 2B ′ including the blue phosphor is usually the same as that of the phosphor portions 2R and 2G. Further, in FIG. 9, parts indicated by the same reference numerals as in FIGS. 1 to 8 represent the same parts as in FIGS.
Furthermore, in addition to transmitting through the phosphor parts 2R and 2G, a reflection type configuration in which the light emitted from the light source 4 is reflected by the phosphor parts 2R and 2G may be applied. Specifically, the display device 1 can be configured by installing the light source 4 in front of the phosphor portions 2R and 2G.

Further, the above-described members such as the phosphor portions 2R and 2G, the light transmission portion 2B, the optical shutter 3, the light source 4, the substrate 5, the microlens array 6, the polarizer 7, and the analyzer 8 do not depart from the gist of the present invention. Any combination can be used within the range.
Further, the display devices 1 and 1 ′ may be used in combination with other constituent members. For example, you may make it employ | adopt a protective film as it describes in the 0039th paragraph or less of Unexamined-Japanese-Patent No. 2005-885066.

In addition to the above members, films having various functions such as antireflection layers, alignment films, retardation films, brightness enhancement films, reflection films, transflective films, and light diffusion films can be added or laminated. You may do it.
The film having these optical functions can be formed, for example, by the following method.

The layer having a function as a retardation film is subjected to, for example, a stretching process described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, or a process described in Japanese Patent No. 3168850. Can be formed.
The layer having a function as a brightness enhancement film may be formed by, for example, forming fine holes by a method described in JP-A No. 2002-169025 or JP-A No. 2003-29030, or selective reflection. It can be formed by superposing two or more cholesteric liquid crystal layers having different center wavelengths.

Furthermore, the layer having a function as a reflective film or a transflective film can be formed using, for example, a metal thin film obtained by vapor deposition or sputtering.
The layer having a function as a diffusion film can be formed by coating the protective film with a resin solution containing fine particles.
Furthermore, the layer having a function as a retardation film or an optical compensation film can be formed by applying and aligning a liquid crystal compound such as a discotic liquid crystal compound or a nematic liquid crystal compound.

  The present invention can be arbitrarily used as a display device using a phosphor, and is particularly suitable for a display device capable of color display.

1 is a schematic diagram showing a structure of a main part of a color display as one embodiment of the present invention. It is sectional drawing which shows typically the principal part structure of an example of LED which can be used for the display apparatus as one Embodiment of this invention. It is sectional drawing which shows typically the principal part structure of an example of LED which can be used for the display apparatus as one Embodiment of this invention. It is sectional drawing which shows typically the principal part structure of the modification of LED which can be used for the display apparatus as one Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view schematically illustrating an enlarged main part of a portion where a light source is installed on a substrate for explaining an embodiment of the present invention. FIG. 2 is a graph illustrating an absorption wavelength and a light emission wavelength of a typical phosphor and an intensity thereof according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view schematically illustrating an example of a configuration that a phosphor part and a light transmission part can take, according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention and schematically illustrating an example of a configuration that a phosphor portion can take. 1 is a schematic diagram showing a structure of a main part of a color display as one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display apparatus 2R, 2G, 2B 'Phosphor part 2B Light transmission part 3 Optical shutter 4 Light source 5 Substrate 6 Micro lens array 7 Polarizer 8 Analyzer 21 Transparent substrate 22, 36 Black matrix 31, 35 Transparent electrode 32, 34 Orientation Film 33 Liquid crystal 100, 110 LED
101 substrate 102 buffer layer 103 first ohmic layer 104 first cladding layer 105 active layer 106 second cladding layer 107 second ohmic layer 108 first electrode 109 second electrode 111 high resistance region 112 raised portion 113 mounting substrate 114 Bump 201 Plate 202 Porous plate

Claims (3)

A phosphor portion containing a phosphor that absorbs excitation light and emits visible light;
An optical shutter that is provided in front of the phosphor part and that transmits the visible light emitted from the phosphor contained in the phosphor part to the front by adjusting the amount of light;
A display device comprising: a light source provided corresponding to the phosphor portion and emitting excitation light of the phosphor toward the phosphor portion. The display device according to claim 1, wherein the light sources are arranged in an array. The display device according to claim 1, wherein the optical shutter is a liquid crystal optical shutter.

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