JP2010129698A - Light emitting device, backlight, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device in which a reflector is arranged in the circumference of the light emitting element with excellent luminous efficiency. <P>SOLUTION: A light emitting device includes a light emitting element, a reflector arranged in the circumference of this light emitting element, and a phosphor layer that is arranged in the light receiving unit of this reflector and has a phosphor absorbing the light emitted by the light emitting element to emit the light with a wavelength different from that of the luminescent color of this light emitting element. In the light emitting device, the inclination of the inner surface of the reflector from the normal of the installation surface where the light emitting element is installed is ≥5° and ≤40°. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting device, a backlight, and a liquid crystal display device, and more particularly to a light emitting device in which a reflector is disposed around a light emitting element, and a backlight and a liquid crystal display device using the light emitting device.

  Compared to mercury-excited fluorescent lamp tubes (FL) and cold cathode ray tubes (CCFL) that have been used for general lighting and backlights for liquid crystal display devices in recent years, they are compact, long-life, low-voltage driven, and mercury-free. The development of white light emitting devices having such features as these has been started.

  The white light emitting device includes a type 1 that emits white light by combining light emitting diodes of three colors, a blue light emitting diode, a green light emitting diode, and a red light emitting diode, and a long wavelength ultraviolet ray (300 to 430 nm) or a blue wavelength ( There is a type 2 which emits white light by combining a light emitting diode of 460 to 480 nm) and a phosphor layer containing a phosphor of single color or a plurality of colors which emits visible light. According to the type 2 white light emitting device, since the number of light emitting diodes can be reduced and the overall heat generation can be suppressed, in recent years, the type 2 white light emitting device has been extensively developed.

  Among type 2 white light-emitting devices, those using light-emitting diodes (hereinafter referred to as ultraviolet light-emitting diodes) that emit long-wavelength ultraviolet light (300 to 430 nm) have three colors of blue, green, and red as phosphors. Using this phosphor, white light is obtained. On the other hand, those using light emitting diodes with blue wavelengths (460 to 480 nm) (hereinafter referred to as blue light emitting diodes) use green and red phosphors or yellow phosphors as phosphors. To obtain white light.

In such a type 2 white light emitting device, for example, a light emitting diode is disposed on a substrate, and a reflector such as a resin frame is disposed so as to surround the light emitting diode, and a fluorescent light adapted to the type of the light emitting diode is disposed in the reflector. It is obtained by arranging a phosphor layer containing a body. By adopting such a structure, light emitted from the light emitting diode is converted into light of a predetermined wavelength by the phosphor layer, and white light is emitted to the outside as a total (for example, patents) Reference 1).
JP 2007-96133 A

  However, when the reflector is simply provided around the light emitting diode, that is, when the mounting surface on which the light emitting diode is mounted, for example, there is almost no inclination of the inner surface of the reflector with respect to the normal of the surface of the substrate, the light emitted from the light emitting diode Since light is reflected by the inner surface of the reflector and enters the light emitting diode again, the luminous efficiency is not necessarily excellent.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a light-emitting device in which a reflector is disposed around a light-emitting diode, which has excellent luminous efficiency. Another object of the present invention is to provide a backlight and a liquid crystal display device using such a light emitting device having excellent luminous efficiency.

  The light emitting device of the present invention includes a light emitting element, a reflector disposed around the light emitting element, and a light receiving portion of the reflector, which absorbs light emitted from the light emitting element and emits light from the light emitting element. And a phosphor layer containing a phosphor that emits light having a wavelength different from that of the reflector, wherein the inclination of the inner surface of the reflector with respect to the normal of the installation surface on which the light emitting element is installed is 5 °. It is characterized by being 40 ° or less.

  The light emitting element emits ultraviolet light having a wavelength shorter than 430 nm, and the phosphor preferably emits light of a long wavelength by absorbing light emitted from the light emitting element.

  The energy ratio between the direct light energy from the light emitting element and the fluorescence energy from the phosphor is preferably 0.1 or less.

  Furthermore, it is preferable that a difference between the size of the light receiving portion on the installation surface side of the reflector and the size of the light emitting element is 1.2 mm or less.

  According to the present invention, a light emitting element, a reflector disposed around the light emitting element, and a light receiving portion of the reflector, which absorbs light emitted from the light emitting element and is an emission color of the light emitting element. In a light emitting device having a phosphor layer containing phosphors that emit light of different wavelengths, the inclination of the inner surface of the reflector from the normal of the installation surface on which the light emitting element is installed is 5 ° or more and 40 ° or less. Thus, a light emitting device having excellent luminous efficiency can be obtained.

  Further, according to the present invention, a backlight and a liquid crystal display device having excellent characteristics can be obtained by using such a light emitting device having excellent luminous efficiency as a light emitting device in a backlight and liquid crystal display device.

The present invention will be described below.
FIG. 1 is an external view showing an example of a light emitting device of the present invention. FIG. 2 is a cross-sectional view (a cross-sectional view taken along line AA) of the light-emitting device shown in FIG.

  The light emitting device 1 has a device main body 4 in which, for example, a frame-like reflector 2 whose light receiving portion is elliptical and a bottom portion 3 provided on one main surface side of the reflector 2 are integrally formed. . A lead electrode 5 and a lead electrode 6 are formed on the surface of the bottom 3 exposed in the frame of the reflector 2, and these are connected to a pair of mounting electrodes 7 and mounting electrodes 8 provided on the side surface through the reflector 2. Has been.

  A light emitting element 9 is disposed on the lead electrode 5, a lower electrode (not shown) of the light emitting element 9 is electrically connected to the lead electrode 5, and an upper electrode (not shown) is connected to the lead electrode 6 via the bonding wire 10. Electrically connected. The light receiving portion of the reflector 2 is filled with a phosphor layer 11 containing a phosphor (not shown).

  The apparatus main body 4 including the reflector 2 and the bottom 3 is made of ceramics such as alumina and aluminum nitride, glass ceramics, glass epoxy resin, thermosetting resin, thermoplastic resin, and the like. The device body 4 is preferably made of ceramics such as alumina or aluminum nitride, for example, because it can have excellent thermal conductivity and the temperature rise of the light emitting device 1 can be suppressed.

  The lead electrode 5 and the lead electrode 6 are made of a metal material such as Ag, Pt, Ru, Pd, and Al. When the lead electrode 5 and the lead electrode 6 are made of such a metal material, the light emitting device 1 having excellent light reflectivity and excellent light emission efficiency can be obtained. In addition, the lead electrode 5 and the lead electrode 6 can be made of, for example, Ni, Cu, Au, or the like in addition to the above-described metal material. Further, the mounting electrode 7 and the mounting electrode 8 can also be made of the same metal material as that of the lead electrode 5 and the lead electrode 6, but it is not always necessary to have excellent light reflectivity. It can be made of Ni, Cu, Au or the like.

  The light emitting element 9 emits, for example, long wavelength ultraviolet light (300 to 430 nm) or blue wavelength (460 to 480 nm). When a light-emitting element that emits long-wavelength ultraviolet light (300 to 430 nm) (hereinafter referred to as an ultraviolet light-emitting element) is used, phosphors of three colors of blue, green, and red are used as the phosphor contained in the phosphor layer 11. White light can be obtained by using the body. On the other hand, when using a light emitting element (hereinafter referred to as a blue light emitting element) having a blue wavelength (460 to 480 nm), as phosphors contained in the phosphor layer 11, two color phosphors of green and red, or White light can be obtained by using a yellow phosphor. In addition, a light emitting diode and a laser can be used as the light emitting element 9, and these are collectively called a light emitting element in the present invention.

  When an ultraviolet light emitting element is used as the light emitting element 9, for example, the following phosphors can be used.

<Blue phosphor>
Specifically, a blue phosphor that emits blue light having a peak wavelength of 430 nm to 460 nm is used as the blue phosphor. As the blue phosphor, for example, a blue phosphor having a composition represented by the following formula (1) or (2) is used.

_{(Sr 1-x-y-} z Ba x Ca y Eu z) 10 (PO 4) 6 X 2 ... (1)
(Wherein x, y, and z are values satisfying 0 ≦ x <0.2, 0 ≦ y <0.1, 0.005 <z <0.1, and X represents F, Cl, (At least one selected from Br.)

  In the formula (1), it is preferable that x and y are in the above ranges because the wavelength of light from the blue phosphor is suitable for backlight use. Further, the longer the x and y are within the above ranges, the longer the light emitting component of the light from the blue phosphor increases. On the other hand, the smaller x and y are within the above ranges, the narrower the spectral width of the light from the blue phosphor, and the more suitable for backlight use. Furthermore, it is preferable that z is in the above range because the luminous efficiency of the blue phosphor is increased.

_{(Ba 1-x-y-} z Sr x Ca y Eu z) MgAl 10 O 17 ... (2)
(In the formula, x, y, and z are values satisfying 0 ≦ x <0.5, 0 ≦ y <0.1, and 0.15 <z <0.4.)

  In the formula (2), it is preferable that x and y are in the above ranges because the wavelength of light from the blue phosphor is suitable for backlight use. In addition, as x and y increase within the above ranges, the long-wavelength light emission component of the light from the blue phosphor slightly increases. Furthermore, it is preferable that z is in the above range because the luminous efficiency of the blue phosphor is increased.

<Green phosphor>
Specifically, a green phosphor that emits green light having a peak wavelength of 490 nm to 575 nm is used as the green phosphor. As the green phosphor, for example, a green phosphor made of europium manganese activated aluminate having a composition represented by the following formula (3) is used.

_{(Ba 1-x-y-} z Sr x Ca y Eu z) (Mg 1-u Mn u) Al 10 O 17 ... (3)
(Wherein x, y, z and u satisfy 0 ≦ x <0.5, 0 ≦ y <0.1, 0.15 <z <0.4 and 0.25 <u <0.6) Value.)

  In the formula (3), it is preferable that z and u are in the above ranges because the green phosphor has high luminous efficiency. Further, it is preferable that x and y are within the above ranges because the green phosphor has a good balance between the lifetime and the luminance. If x is 0.5 or more, the lifetime of the green phosphor may be reduced.

<Red phosphor>
Specifically, a red phosphor that emits red light having a peak wavelength of 620 nm to 780 nm is used as the red phosphor. As the red phosphor, for example, europium activated lanthanum oxysulfide having a composition represented by the following formula (4) is used.

_{(La 1-x-y Eu} x M y) 2 O 2 S ... (4)
(In the formula, M is at least one element selected from Sb, Sm, Ga and Sn, and x and y are values satisfying 0.08 <x <0.17 and 0 ≦ y <0.003. .)

  In the formula (4), it is preferable that M is at least one element selected from Sb, Sm, Ga and Sn because the luminous efficiency of the red phosphor is high. Moreover, it is preferable that x and y are within the above ranges because the wavelength of light from the red phosphor is suitable for backlight use.

  In the present invention, in such a light emitting device 1, as shown in FIG. 3, for example, the inclination θ of the inner surface 2a of the reflector 2 from the normal of the surface of the light emitting element 9, that is, the surface of the bottom 3, is 40 ° or more. It is characterized by being below. FIG. 3 is a cross-sectional view of the light emitting device 1 shown in FIG.

  By providing such an inclination θ on the inner surface 2a of the reflector 2, the light emission efficiency of the light emitting device 1 can be improved as compared with a conventional apparatus having almost no inclination. In addition, since the light emission efficiency is improved, the power applied to the light emitting device 1 can be reduced to suppress the temperature rise, and thus the reliability can be improved.

  That is, the light emitted from the light emitting element 9 is directed to the opening of the reflector 2 which is the upper part thereof, but the traveling direction is bent in the horizontal direction by colliding with the phosphor contained in the phosphor layer 11, As a result, the light enters the inner surface 2a of the reflector 2. At this time, when the inner surface 2 a has almost no inclination, the light incident on the inner surface 2 a is reflected as it is in the horizontal direction and enters the light emitting element 9 again. For this reason, the light emitted from the light emitting element 9 is not effectively used, and the light emission efficiency is not necessarily excellent.

  In the present invention, by setting the inclination θ of the inner surface 2a of the reflector 2 to 5 ° or more and 40 ° or less, the light emitted from the light-emitting element 9 is prevented from entering the light-emitting element 9 again, thereby improving the luminous efficiency. It can be excellent.

  Here, when the inclination θ is less than 5 °, the effect of suppressing re-incident on the light emitting element 9 is low, and the light emission efficiency cannot be sufficiently improved. On the other hand, if the inclination θ is about 40 °, the light emission efficiency can be sufficiently improved. If the inclination θ is increased beyond this, the light emission efficiency cannot be expected to be improved, but the opening of the reflector 2 becomes larger. This is not preferable because the size of the light emitting device 1 is increased.

  If the inclination θ is 5 ° or more and 40 ° or less, the light emission efficiency can be effectively improved, but it is preferably 10 ° or more, more preferably 15 ° or more, and further preferably 20 ° or more. By setting the inclination θ to such a value, the light emission efficiency can be further improved.

  Here, when the opening of the reflector 2 has an elliptical shape as shown in FIG. 1, the inner surface 2a of the reflector 2 is roughly divided into two types, that is, surfaces having a relatively small area facing each other in the longitudinal direction of the reflector 2. (Two surfaces on the lower left and upper right in FIG. 1) and a relatively large surface (two surfaces on the upper left and lower right in FIG. 1) facing each other in the direction perpendicular to the longitudinal direction. In such a case, it is only necessary that the slope θ of the surface having a relatively large area facing at least in the direction perpendicular to the longitudinal direction is within the above range. As described above, the predetermined inclination θ is provided on the surface having a relatively large area, so that the re-incidence to the light emitting element 9 can be effectively suppressed and the light emission efficiency can be improved.

Further, when the inner surface 2a is not a uniform plane, for example, when it is composed of two planes 2b and 2c as shown in FIG. 4, each plane from the installation surface of the light emitting element 9, that is, the surface of the bottom 3 to a height of 100 μm. The average value of the gradients θ ₁ and θ ₂ of 2b and 2c is defined as the gradient θ. Specifically, the average values obtained by weighting the inclinations θ ₁ and θ ₂ of the planes 2b and 2c with the lengths of the planes 2b and 2c (the length from the surface of the bottom 3 to a height of 100 μm) are inclined. Let θ. The same applies to the case where the inner surface 2a is composed of three or more planes.

  On the other hand, when the inner surface 2a is curved as shown in FIG. 5, for example, the average value of the differential gradient from the installation surface of the light emitting element 9, that is, the surface of the bottom 3, to a height of 100 μm is defined as the inclination θ. Specifically, Δx is measured every Δy (5 μm), and an average value of 20 arctan (Δx / 5) is defined as a slope θ.

The light emission efficiency is improved by providing such an inclination θ, as shown in the cross-sectional view of FIG. 3 or the plan view of FIG. 6, by reducing the size of the light receiving portion (the installation surface side of the light emitting element 9) of the reflector 2 to L. _1, and if the size of the light emitting element 9 was _{L 2,} these differences _(L 1 -L ₂₎ becomes significant in the case of 1.2mm or less. Incidentally, when the opening portion of the reflector 2 as shown in Figure 1 is such as elliptical shape, size L ₁ of the light receiving portion of the reflector _2, the size L ₂ of the light-emitting element 9, for example, longitudinal direction as shown in FIG. 6 The size (width) in the direction perpendicular to.

When the difference (L ₁ −L ₂ ) exceeds 1.2 mm, the inner surface 2a of the reflector 2 and the side surface of the light emitting element 9 are too far apart, so that the light emitted from the light emitting element 9 is reflected by the inner surface 2a in the first place. Thus, the light is not incident on the light emitting element 9 again, and even if the inner surface 2a is provided with a predetermined inclination θ, the light emission efficiency cannot always be improved. When the difference (L ₁ −L ₂ ) is 1.2 mm or less, the light emitted from the light emitting element 9 is reflected by the inner surface 2a and is incident on the light emitting element 9 again. By providing, re-incidence to the light emitting element 9 can be suppressed and the light emission efficiency can be remarkably improved.

  In addition, the luminous efficiency is improved by providing the predetermined inclination θ. The above-described ultraviolet light emitting element is used as the light emitting element 9, and the phosphors contained in the phosphor layer 11 are blue, green, and red. This is remarkable when a phosphor is used.

  That is, when an ultraviolet light emitting element is used as the light emitting element 9 and phosphors of three colors of blue, green, and red are used as the phosphor contained in the phosphor layer 11, ultraviolet light emitted from the ultraviolet light emitting element is emitted. In order to suppress the emission to the outside of the light emitting device 1, it is necessary to increase the density of the phosphor contained in the phosphor layer 11. When the density of the phosphor is increased, the probability that the light emitted from the light emitting element 9 collides with the phosphor contained in the phosphor layer 11 and the traveling direction is bent in the horizontal direction increases, and as a result, the inner surface 2a. The probability that the light enters the light source, is reflected, and reenters the light emitting element 9 is also increased.

  Accordingly, an ultraviolet light emitting element is used as the light emitting element 9 and phosphors of three colors of blue, green, and red are used as the phosphor contained in the phosphor layer 11, and a predetermined inclination is applied to the inner surface 2a of the reflector 2. By providing θ, re-incidence to the light emitting element 9 can be suppressed and the light emission efficiency can be remarkably improved.

  Furthermore, the luminous efficiency is improved by providing a predetermined inclination θ. The energy ratio between the direct light energy from the light emitting element 9 and the fluorescent energy from the phosphor contained in the phosphor layer 11 (direct light energy). / Fluorescence energy) becomes remarkable when the energy is 0.1 or less. The energy of each light is measured as a spectrum of the total luminous flux of the light emitting device using an integrating sphere and a spectroscope, the energy of direct light is the energy of the wavelength component corresponding to the spectrum unique to the light emitting element, and the energy of the fluorescence is the phosphor used It is measured as the energy of the wavelength component corresponding to the emission spectrum.

  That is, the energy ratio varies depending on the output of the light emitting element 9 and the mass density of the phosphor contained in the phosphor layer 11, but the energy of the direct light from the light emitting element 9 is such that the energy ratio is 0.1 or less. By providing the predetermined inclination θ when the amount is small, direct light with low energy from the light emitting element 9 can be effectively used, and the light emission efficiency can be remarkably improved.

  Next, another example of the light emitting device of the present invention will be described. FIG. 7 is an external view showing another example of the light emitting device of the present invention. FIG. 8 is a cross-sectional view of the light emitting device shown in FIG. In the following description, parts having the same functions as those of the light emitting device 1 shown in FIGS.

  In the light emitting device 1, a light emitting element 9 is disposed on one main surface of a substrate 12, and a frame-shaped reflector 2 having a rectangular light receiving portion is provided so as to surround the light emitting element 9. The light receiving portion of the reflector 2 is filled with a phosphor layer 11 containing a phosphor (not shown).

  The substrate 12 is in the form of a plate made of an insulator, and a lead electrode 5 and a lead electrode 6 are formed on the main surface side where the light emitting element 9 is disposed. The light emitting element 9 is disposed on the lead electrode 5, and a lower electrode (not shown) is electrically connected to the lead electrode 5, and an upper electrode (not shown) is electrically connected to the lead electrode 6 through the bonding wire 10. ing.

  Further, the mounting electrode 7 and the mounting electrode 8 are formed on the main surface of the substrate 12 opposite to the main surface on which the light emitting element 9 is disposed, and these are respectively connected to the lead electrode 5 and the power supply via 13 and the power supply via 14. The lead electrode 6 is electrically connected.

  In the light emitting device 1 having the structure in which the reflector 2 is arranged on the substrate 12 as described above, similarly to the light emitting device 1 shown in FIGS. 1 and 2, by providing a predetermined inclination θ on the inner surface 2 a of the reflector 2, The light emission efficiency of the light emitting device 1 can be improved as compared with the one having almost no inclination. In addition, since the light emission efficiency is improved, the power applied to the light emitting device 1 can be reduced to suppress the temperature rise, and thus the reliability can be improved.

  Next, the manufacturing method of the light-emitting device 1 of this invention is demonstrated. For the light emitting device 1 of the present invention, a known method for manufacturing a light emitting device can be applied except that a predetermined inclination θ is provided on the inner surface 2a of the reflector 2.

  For example, when manufacturing the light-emitting device 1 as shown in FIGS. 7 and 8, first, the lead electrode 5 and the lead electrode 6 are formed as the substrate 12, and the power supply via 13 is provided to each of the lead electrode 5 and the lead electrode 6. Then, a device in which the mounting electrode 7 and the mounting electrode 8 are formed through the power supply via 14 is manufactured.

  Thereafter, an ultraviolet light emitting element, for example, is bonded as a light emitting element 9 on the lead electrode 5 of the substrate 12, and a lower electrode (not shown) of the light emitting element 9 and the lead electrode 5 are electrically connected, and an upper electrode (not shown) The lead electrode 6 is electrically connected by a bonding wire 10.

  On the other hand, a rectangular frame or the like is manufactured as the reflector 2. At this time, the inclination θ of the inner surface 2a is adjusted so that the inclination θ of the inner surface 2a from the normal of the surface of the substrate 12 to be the installation surface of the light emitting element 9 is within a predetermined range when bonded to the substrate 12. To do. Thereafter, the reflector 2 having the inner surface 2a of which the inclination θ is adjusted is joined to the substrate 12 to which the light emitting element 9 has been previously joined so as to surround the light emitting element 9.

  Separately, a blue phosphor, a green phosphor and a red phosphor are mixed in a transparent resin such as a silicone resin to prepare a phosphor slurry. The phosphor slurry is joined to the substrate 12 to receive light. The phosphor layer 11 is cured by heat treatment, and the light emitting device 1 is completed.

  Although the light emitting device 1 of the present invention has been described above, the light emitting device 1 of the present invention is not necessarily limited to the above. For example, the light emitting element 9 may have a pair of electrodes formed on the top thereof, and each of such a pair of electrodes is electrically connected to the lead electrode 5 and the lead electrode 6 by a bonding wire 10. It doesn't matter.

  Further, for example, in the light emitting device 1 shown in FIGS. 7 and 8, the lead electrode 5 and the lead electrode 6 are arranged so that the end surface of the substrate 12 faces the surface without using the power supply via 13 and the power supply via 14. The mounting electrode 7 and the mounting electrode 8 may be connected. Each of such electrodes may be plate-shaped or film-shaped.

  Furthermore, the light emitting device 1 of the present invention may be a so-called top view type that emits light in a direction perpendicular to the surface of the mounting substrate on which the light emitting device 1 is mounted, and is parallel to the surface of the mounting substrate. It may be a so-called side view type that emits light in any direction.

  Such a light emitting device 1 of the present invention can be suitably used as a light source of a backlight by arranging a plurality of the light emitting devices 1 in a linear or planar shape. Further, such a backlight can be suitably used as a light source for various liquid crystal display devices such as small screens of mobile phones, car navigation systems, mobile communication devices, and medium / large screens of personal computers and televisions.

  FIG. 9 is a cross-sectional view schematically showing a backlight 20 using the light emitting device 1 of the present invention and a liquid crystal display device 30 using the backlight 20. The backlight 20 is of a direct type, and includes, for example, a substrate 21 and a plurality of light emitting devices 1 arranged on the substrate 21 in a planar direction. In addition, the liquid crystal display device 30 includes, for example, an optical sheet portion 31 provided so as to cover the light emitting surface side of the backlight 20 and a liquid crystal panel 32 provided so as to cover the outside of the optical sheet portion 31. is doing.

  The optical sheet portion 31 is composed of, for example, a pair of diffusion sheets 31a and 31b and a prism sheet 31c sandwiched between the pair of diffusion sheets 31a and 31b, and an inner frame portion 33 composed of resin, metal, or the like. Is fixed to the backlight 20.

  In the liquid crystal panel 32, for example, an array substrate, which is a glass plate in which a transparent electrode is formed between two polarizing plates, and a color filter substrate are disposed so as to face each other, and between the array substrate and the color filter substrate. Liquid crystal is injected to form a liquid crystal layer, and blue (B), green (G), and red (R) color filters are formed on the color filter substrate corresponding to each pixel. Such a liquid crystal panel 32 is fixed to the backlight 20 by an outer frame portion 34 made of resin, metal or the like so as to cover the optical sheet portion 31.

  Although the backlight and the liquid crystal display device of the present invention have been described above, the form of the backlight of the present invention is not limited as long as the light emitting device of the present invention is applied. It may be a direct-type backlight as shown, or a sidelight-type backlight (not shown). Further, the form of the liquid crystal display device of the present invention is not limited as long as the backlight of the present invention is applied, and a direct type backlight as shown in FIG. 9 is applied. There may be used a side light type backlight (not shown).

  Next, the light-emitting device 1 of the present invention will be described in more detail with reference to examples.

Example 1
The light emitting device 1 having the structure shown in FIGS. 1 and 2 was manufactured, and the luminous efficiency was measured by changing the inclination θ of the inner surface 2 a facing in the direction perpendicular to the longitudinal direction of the reflector 2.

Here, the overall size of the light emitting device 1 was 3 mm in length, 2 mm in width, and 1.2 mm in height. The light-emitting element 9 was a blue light-emitting diode having a length of 400 μm, a width (L ₂ ) of 400 μm, a height of 150 μm, an emission peak wavelength of 460 μm, and a half-value width of 10 nm. Furthermore, the phosphor contained in the phosphor layer 11 was a YAG phosphor having a particle size of 25 μm, and the mass density of the phosphor contained in the phosphor layer 11 was 55%.

The reflector 2 has an elliptical shape of the light receiving portion, specifically, a shape in which each corner of the rectangle is rounded, and the length of the light receiving portion (the light emitting element 9 installation surface side) is 2000 μm in width. (L ₁ ) was 1300 μm, the radius of curvature of the four corners was 650 μm, and the height (depth) was 650 μm. Incidentally, the width _{L 1} of the light receiving portion of the reflector 2, the difference between the width _{L 2} of the light-emitting element 9 _(L 1 -L ₂₎ is 0.9 mm. Note that the luminous efficiency was measured as a luminous flux per unit power by using a total luminous flux measuring device SLMS-1021 manufactured by Labsphere and comparing with the input power.

  The results are shown in FIG. In addition, the result was shown by the relative value on the basis of the luminous efficiency of the light-emitting device 1 when inclination (theta) was 0 degree.

  As shown in FIG. 10, it can be seen that the luminous efficiency increases by increasing the inclination θ. In particular, it can be seen that the luminous efficiency is significantly increased by setting the inclination θ to 5 ° or more. Further, it is understood that the inclination θ is preferably 10 ° or more, more preferably 15 ° or more, and further preferably 20 ° or more.

(Example 2)
An ultraviolet light emitting diode having an emission peak wavelength of 410 μm and a half-value width of 10 nm is used as the light-emitting element 9, and the phosphors included in the phosphor layer 11 are three-color phosphors of a blue phosphor, a green phosphor, and a red phosphor. , Sr ₁₀ (PO ₄ ) ₆ Cl ₁₂ : Eu as the blue phosphor, BaMgAl ₁₀ O ₁₇ : Eu, Mn as the green phosphor, La ₂ O ₂ S: Eu as the red phosphor, and the average particle diameter of the phosphor The light emitting device 1 is manufactured in the same manner as in Example 1 except that the mass density of the phosphor contained in the phosphor layer 11 is 60%, and the inclination θ of the inner surface 2a of the reflector 2 is changed. Luminous efficiency was measured. The results are shown in FIG.

  As shown in FIG. 11, it can be seen that the luminous efficiency increases by increasing the inclination θ. In particular, it can be seen that the luminous efficiency is significantly increased by setting the inclination θ to 5 ° or more.

(Example 3)
The light emitting device 1 having the structure shown in FIGS. 7 and 8 was manufactured, and the luminous efficiency was measured by changing the inclination θ of the inner surface 2 a facing in the direction perpendicular to the longitudinal direction of the reflector 2.

Here, the overall size of the light emitting device 1 was 2.8 mm in length, 0.8 mm in width, and 1.2 mm in height. The light-emitting element 9 was a blue light-emitting diode having a length of 460 μm, a width (L ₂ ) of 260 μm, a height of 150 μm, an emission peak wavelength of 460 μm, and a half-value width of 10 nm. Furthermore, the phosphor contained in the phosphor layer 11 was a YAG phosphor having a particle size of 25 μm, and the mass density of the phosphor contained in the phosphor layer 11 was 60%.

As shown in FIG. 7, the reflector 2 has a rectangular shape of the light receiving portion, the length of the light receiving portion (on the side where the light emitting element 9 is installed) is 2000 μm, and the width (L ₁ ) is 600 μm. The (depth) was set to 650 μm. The difference (L ₁ −L ₂ ) between the width L ₁ of the light receiving portion of the reflector 2 on the installation surface side of the light emitting element 9 and the width L ₂ of the light emitting element 9 is 1.7 mm.

  The results are shown in FIG. In addition, the result was shown by the relative value on the basis of the luminous efficiency of the light-emitting device 1 when inclination (theta) was 0 degree.

  As shown in FIG. 12, it can be seen that the luminous efficiency increases by increasing the inclination θ of the inner surface 2a of the reflector 2. In particular, it can be seen that the luminous efficiency is significantly increased by setting the inclination θ to 5 ° or more.

Example 4
An ultraviolet light emitting diode having an emission peak wavelength of 410 μm and a half-value width of 10 nm is used as the light-emitting element 9, and the phosphors included in the phosphor layer 11 are three-color phosphors of a blue phosphor, a green phosphor, and a red phosphor. , Sr ₁₀ (PO ₄ ) ₆ Cl ₁₂ : Eu as the blue phosphor, BaMgAl ₁₀ O ₁₇ : Eu, Mn as the green phosphor, La ₂ O ₂ S: Eu as the red phosphor, and the average particle diameter of the phosphor The light emitting device 1 is manufactured in the same manner as in Example 3 except that the mass density of the phosphor contained in the phosphor layer 11 is 60%, and the inclination θ of the inner surface 2a of the reflector 2 is changed. Luminous efficiency was measured. The results are shown in FIG.

  As shown in FIG. 13, it can be seen that the luminous efficiency increases by increasing the inclination θ of the inner surface 2 a of the reflector 2. In particular, it can be seen that the luminous efficiency is significantly increased by setting the inclination θ to 5 ° or more.

(Example 5)
The light emitting device 1 having the structure shown in FIGS. 1 and 2 is manufactured with a reflector 2 having an inner surface 2a with an inclination θ of 20 ° and 0 °, and a light receiving portion of the reflector 2 (installation of the light emitting element 9). the width of the side) _{(L 1),} to measure the luminous efficiency by changing the difference between the width of the light emitting element _{9 (L 2) (L 1} -L 2).

In the light emitting device 1, the width (L ₂ ) of the light emitting element 9 is set to 260 μm, and the width (L ₁ ) of the light receiving portion (the installation surface side of the light emitting element 9) of the reflector 2 is changed in the range of 600 μm to 1860 μm. The configuration was basically the same as that of the light-emitting device 1 of Example 2 except that the difference (L ₁ −L ₂ ) was changed.

  The results are shown in FIG. The result is the ratio of the light emission efficiency of the light emitting device 1 with the inclination θ of 20 ° to the light emission efficiency of the light emitting device 1 with the inclination θ of 0 ° (light emission efficiency (inclination θ = 20 °) / light emission efficiency (inclination θ). = 0 °)).

As can be seen from FIG. 14, when the difference (L ₁ −L ₂ ) is 1200 μm or less, the luminous efficiency can be greatly improved by providing a predetermined inclination θ on the inner surface 2 a of the reflector 2.

(Example 6)
7 and 8 are manufactured in which the inclination θ of the inner surface 2a of the reflector 2 is set to 20 ° and to 0 °, and the energy and fluorescence of the direct light from the light emitting element 9 are manufactured. Luminous efficiency was measured by changing the energy ratio (direct light energy / fluorescence energy) with the energy of fluorescence from the phosphor in the body layer 11.

  The energy ratio was adjusted by changing the mass density of the phosphor contained in the phosphor layer 11. The light emitting device 1 basically uses Example 4 except that an ultraviolet light emitting diode having an emission peak wavelength of 405 μm and a half width of 10 nm is used as the light emitting element 9 and the mass density of the phosphor in the phosphor layer 11 is changed. It was set as the structure similar to the light-emitting device 1 of.

  The results are shown in FIG. The result is the ratio of the light emission efficiency of the light emitting device 1 with the inclination θ of 20 ° to the light emission efficiency of the light emitting device 1 with the inclination θ of 0 ° (light emission efficiency (inclination θ = 20 °) / light emission efficiency (inclination θ). = 0 °)).

  As can be seen from FIG. 15, when the energy ratio is 0.1 or less, the luminous efficiency can be significantly improved by providing a predetermined inclination θ on the inner surface 2 a of the reflector 2.

1 is an external view illustrating an example of a light-emitting device of the present invention. Sectional drawing of the light-emitting device shown in FIG. Explanatory drawing explaining inclination (theta) of the inner surface of a reflector. Explanatory drawing explaining how to obtain | require inclination | tilt (theta) when the inner surface of a reflector consists of two planes. Explanatory drawing explaining how to obtain | require inclination | tilt (theta) when the inner surface of a reflector is curved shape. Explanatory drawing explaining the magnitude | size (width) of the light-receiving part of a reflector, and the magnitude | size (width) of a light emitting element. FIG. 6 is an external view illustrating another example of the light-emitting device of the present invention. Sectional drawing of the light-emitting device shown in FIG. Sectional drawing which shows an example of the backlight of this invention, and a liquid crystal display device. FIG. 4 is a diagram showing the results of Example 1. The figure which shows the result of Example 2. FIG. FIG. 6 shows the results of Example 3. The figure which shows the result of Example 4. FIG. FIG. 6 shows the results of Example 5. The figure which shows the result of Example 6. FIG.

Explanation of symbols

1 ... light emitting device, 2 ... reflector, 2a, 2b, 2c ... inner surface of the reflector, 9 ... light emitting element, 11 ... phosphor layer, 20 ... backlight, 30 ... liquid crystal display device, L 1 _... light receiving portion of the reflector (light emitting Element installation surface side) size (width), L ₂ ... light emitting element size (width), θ ... inclination of reflector inner surface

Claims (6)

A light emitting element, a reflector disposed around the light emitting element, and a light receiving portion of the reflector, which absorbs light emitted from the light emitting element and emits light having a wavelength different from the emission color of the light emitting element. A light emitting device comprising a phosphor layer containing a phosphor to be emitted,
The light emitting device, wherein an inclination of an inner surface of the reflector from a normal line of an installation surface on which the light emitting element is installed is 5 ° or more and 40 ° or less.   The light emitting device emits ultraviolet light having a wavelength shorter than 430 nm, and the phosphor emits light of a long wavelength by absorbing light emitted from the light emitting device. Light-emitting device.   3. The light emitting device according to claim 1, wherein an energy ratio of energy of direct light from the light emitting element to energy of fluorescence from the phosphor is 0.1 or less.   4. The light emitting device according to claim 1, wherein a difference between the size of the light receiving portion on the installation surface side of the reflector and the size of the light emitting element is 1.2 mm or less. 5.   A backlight comprising the light-emitting device according to claim 1.   A liquid crystal display device comprising the backlight according to claim 5.

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