JP2011204888A - Light-emitting device and backlight module using the same - Google Patents

Abstract

Light emitted from a light emitting element is efficiently incident on a light guide plate, and the light distribution in the light guide plate can be made uniform.
A light emitting device includes a light emitting element made of a semiconductor having a waveguide, and an optical element having a diffraction grating provided in the propagation direction of the emitted light from the light emitting element and receiving the emitted light. And a phosphor layer 35 formed on the surface of the optical element 30 opposite to the diffraction grating 30a.
[Selection] Figure 4

Description

  The present invention relates to a light emitting device and a backlight module using the same.

In recent years, the market of liquid crystal display devices using liquid crystal panels as display devices such as flat-screen televisions has been rapidly growing. The liquid crystal display device uses a liquid crystal panel as a transmissive light modulation element, and irradiates the liquid crystal panel with light from a light source device disposed on the back surface thereof. The liquid crystal panel irradiated with light forms an image by controlling the light transmittance.

  Conventionally, a cold cathode fluorescent lamp (CCFL) has been used as a light source of the light source device. However, in recent years of energy saving and mercury-less trend, a semiconductor laser element or LED (Light Emitting Diode) is used. Development of a light source device using a semiconductor light emitting element such as As an example of a light source device using a semiconductor laser element as a light source, for example, it is shown in the following Non-Patent Document 1, and a structure combined with an optical fiber using the high directivity of the semiconductor laser element is proposed. Yes. On the other hand, there are mainly two types of LED light source devices, which are light source devices using LEDs as the light source. There has been proposed an edge type in which LEDs are arranged in a portion and light is irradiated from the back surface of a liquid crystal panel by a light guide plate.

  Currently, for light source devices that use semiconductor laser elements as the light source, there is a need for a vibrator to combat speckle noise that occurs due to the high interference of the laser light source, and the light from the laser light source It has not been marketed yet because it is difficult to spread it uniformly. On the other hand, LED light source devices are rapidly spreading. Currently, the LED light source device is mainly the direct type, but it is considered that the edge type will be widely used in accordance with the demand for a thinner liquid crystal display device in the future. However, the LED light source device used in the edge-type liquid crystal display device has a problem that the efficiency of incident light on the light guide plate of the light emitted from the LED chip is poor and the utilization efficiency of the light emitted from the LED chip is low.

  In order to solve this problem, for example, Patent Document 1 below proposes a structure in which the surface of an LED chip is covered with a scattering lens that is a cylindrical lens.

  Hereinafter, the prior art described in Patent Document 1 will be described with reference to FIG. In FIG. 16, the light source device 224 includes a substrate 223, an LED chip 224a, and a scattering lens 224c. A plurality of LED chips 224a are linearly arranged on the component mounting surface 223a of the substrate 223. The scattering lens 224c, which is a cylindrical lens, covers the LED chip 224a. At this time, the scattering lens 224c is formed to include a curved surface 224c2 that is convex with respect to the component mounting surface 223a, and a tapered surface 224c1 that is tapered from the end of the curved surface toward the component mounting surface 223a. . In this configuration, light emitted from the LED chip 224a is emitted in all directions from the surface of the LED chip 224a toward the front surface of the component mounting surface 223a, and a part of the light is refracted by the curved surface 224c2 of the scattering lens 224c. The remaining portion of the light is reflected by the tapered surface 224 c 1, further refracted by the curved surface 224 c 2, and guided to the light guide plate 221.

JP 2009-158274 A

JOURNAL OF DISPLAY TECHNOLOGY, VOL. 5, NO. 11, (2009), pp 414-417

  However, the liquid crystal display device using the conventional LED light source device has a problem that the light guide plate cannot be thinned. At present, the size of the LED chip is about 0.5 mm × 0.5 mm. The emission angle of the light emitted from the LED chip is so-called Lambertian, and light having a full width at half maximum of 120 ° is emitted. In order to efficiently collect the emitted light having such a radiation characteristic by the lens, the size of the lens needs to be about 5 to 10 times the size of the LED chip. That is, since the size of the lens needs to be about 2.5 mm to 5 mm, it is necessary to increase the thickness of the light guide plate to the same level as the lens in order to efficiently guide light to the light guide plate. As a result, it becomes a limitation when the liquid crystal panel is thinned.

  Further, as described above, similarly to the thickness direction of the light guide plate, the light emission angle is Lambertian, that is, 120 °, and a plurality of LED chips are usually arranged at a predetermined interval. For this reason, the incidence of light in a direction parallel to the light guide plate decreases the light intensity in the region between the LED chips, which is the connection portion of the light guide plate to the light source device. As a result, there is a problem that the uniformity of the light distribution inside the light guide plate becomes insufficient.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems and to make light emitted from a light emitting element efficiently enter a light guide plate and make the light distribution in the light guide plate uniform.

  In order to achieve the above object, according to the present invention, a light emitting device is configured to transmit outgoing light emitted from a light emitting element through an optical element having a diffraction grating or a concave portion and a phosphor layer.

  Specifically, a first light emitting device according to the present invention includes a light emitting element made of a semiconductor having a waveguide, an optical element having a diffraction grating provided in the propagation direction of the emitted light from the light emitting element, and receiving the emitted light. And a phosphor layer formed on a surface opposite to the diffraction grating in the optical element.

  According to the first light emitting device, since the optical element having the diffraction grating that receives the emitted light is provided, a part of the emitted light is diffracted by the diffraction grating, and thus the aspect ratio of the emitted light (the light in the x-axis direction) A light-emitting device having a large value (ratio between the divergence angle and the divergence angle of light in the y-axis direction) can be realized. For this reason, the light emitted from the light emitting element can be efficiently incident on the light guide plate, and the light distribution in the light guide plate can be made uniform. As a result, even in the thin light guide plate of the backlight module, the optical coupling rate between the light emitting device and the light guide plate can be increased.

  In the first light emitting device, the cross-sectional shape of the light emitting end face of the waveguide may be a rectangular shape whose long side is parallel to the extending direction of the grating pattern in the diffraction grating.

  In this way, it is possible to further increase the light divergence angle in the direction in which the aspect ratio of the light emitted from the light emitting element is large.

  In the first light-emitting device, the diffraction grating may have a grating pattern with irregular grating intervals.

  In this way, a light source having a radiation angle characteristic with a very large aspect ratio value can be realized.

  The first light-emitting device may further include a reflective film that reflects the emitted light from the light-emitting element and makes the reflected emitted light incident on the diffraction grating.

  In this way, since the direction of emission of the emitted light from the light emitting element can be changed by the reflective film, the degree of freedom of the arrangement position of the optical element relative to the light emitting element is improved.

  In this case, the light emitting element is a double-sided emission type light emitting element, and the reflection films may be provided on one light emitting end face side and the other light emitting end face side of the light emitting element, respectively.

  In this way, a light source with a larger aspect ratio of emitted light can be realized.

  A second light-emitting device according to the present invention includes a light-emitting element made of a semiconductor having a waveguide, an optical element having a semi-cylindrical recess that is provided in the propagation direction of light emitted from the light-emitting element, and that receives the emitted light; And a phosphor layer formed on a surface opposite to the concave portion of the optical element.

  According to the second light emitting device, since the optical element having the semicylindrical concave portion that receives the outgoing light is provided, the outgoing light is refracted by the semicylindrical concave portion of the optical element. A light emitting device having a large value can be realized. For this reason, the light emitted from the light emitting element can be efficiently incident on the light guide plate, and the light distribution in the light guide plate can be made uniform. As a result, even in the thin light guide plate of the backlight module, the optical coupling rate between the light emitting device and the light guide plate can be increased.

  In the second light emitting device, the cross-sectional shape of the light exit end face of the waveguide may be a rectangular shape whose long side is parallel to the central axis direction of the recess.

  In this way, it is possible to further increase the light divergence angle in the direction in which the aspect ratio of the light emitted from the light emitting element is large.

  In the second light emitting device, the optical element may be formed in a convex shape in which the surface opposite to the surface on which the concave portion is formed is along the concave portion.

  In this way, since the refracted light is uniformly transmitted through the phosphor layer formed on the convex surface of the optical element, the color rendering properties of the emitted light can be improved.

  In the second light emitting device, a diffraction grating may be provided in the concave portion of the optical element.

  If it does in this way, according to the emitted light pattern converted by the crevice of an optical element, the shape of a crevice (concave shape) can be formed with a higher degree of freedom.

  In the first or second light emitting device, a semiconductor laser element or a super luminescent diode can be used as the light emitting element.

  In this way, it is possible to reliably obtain a light source having a large aspect ratio of emitted light. Further, when a super luminescent diode is used, speckle noise can be reduced, so that the image quality of the image display device can be improved.

  A first backlight module according to the present invention includes the first light emitting device of the present invention and a light guide plate that receives light emitted from the first light emitting device on its side surface.

  A second backlight module according to the present invention includes the second light emitting device of the present invention and a light guide plate that receives light emitted from the second light emitting device on its side surface.

  According to the first or second backlight module, a light source having a large aspect ratio value of emitted light can be realized. Therefore, the light emitted from the light emitting element can be efficiently incident on the light guide plate, and the light distribution in the light guide plate can be made uniform. Therefore, even in the thin light guide plate of the backlight module, the light emitting device The optical coupling rate between the light guide plate and the light guide plate can be increased.

  In the first or second backlight module, the cross-sectional shape of the light emitting end face of the waveguide of the optical element may be a rectangular shape whose short side is parallel to the in-plane direction of the main surface of the light guide plate.

  In this way, the light divergence angle in the direction with a large aspect ratio in the light emitted from the light emitting element can be further increased, so that the light distribution in the plane of the light guide plate can be made more uniform.

  In the first or second backlight module, a semiconductor laser element or a super luminescent diode can be used as the light emitting element.

  In this way, it is possible to reliably obtain a light source having a large aspect ratio of emitted light. Further, when a super luminescent diode is used, speckle noise can be reduced, so that the image quality can be improved.

  According to the light emitting device and the backlight module using the same according to the present invention, the light emitted from the light emitting element can be efficiently incident on the light guide plate, and the light distribution in the light guide plate can be made uniform.

1A and 1B show a light emitting device according to a first embodiment of the present invention and a backlight module using the same, FIG. 1A is a front view, and FIG. ) Is a cross-sectional view taken along line Ib-Ib in FIG. 2A to 2C show a light emitting device according to the first embodiment of the present invention and a backlight module using the same, and FIG. 2A is a perspective view of the light emitting device. 2 (b) is an exploded perspective view of the backlight module, and FIG. 2 (c) is a perspective view schematically showing how light from the light emitting device in the backlight module propagates. FIG. 3 is a cross-sectional view showing the light emitting device according to the first embodiment of the present invention. 4A to 4C schematically show the operation of the light-emitting device according to the first embodiment of the present invention. FIG. 4A is a cross-sectional view of the light-emitting device, and FIG. ) Is a perspective view showing light emitted from the light emitting element, and FIG. 4C is a perspective view showing light emitted through the diffraction grating. FIG. 5A shows the diffraction grating in the light emitting device according to the first embodiment of the present invention, and FIG. 5B shows the angle dependence of the light intensity by calculation in the light emitting element according to the first embodiment of the present invention. FIG. 5C is a graph showing the angular dependence of the light intensity by calculation in the light emitting device according to the first embodiment of the present invention. 6 (a) to 6 (d) show a light emitting device according to a modification of the first embodiment of the present invention, FIG. 6 (a) shows a diffraction grating, and FIG. 6 (b) shows a diffraction grating. FIG. 6C is a graph showing the angular dependence of the light intensity calculated in the light emitting element, and FIG. 6D is the angular dependence of the light intensity calculated in the light emitting device. It is a graph which shows. 7 (a) and 7 (b) show a light emitting device according to a second embodiment of the present invention, FIG. 7 (a) is a sectional view, and FIG. 7 (b) is an exploded perspective view (partially). Are omitted). FIG. 8 is a sectional view showing a light emitting device according to a first modification of the second embodiment of the present invention. FIG. 9 is a cross-sectional view showing a light emitting device according to a second modification of the second embodiment of the present invention. FIG. 10A to FIG. 10C show a light emitting device according to a third embodiment of the present invention and a backlight module using the same, and FIG. 10A is a perspective view of the light emitting device. 10 (b) is an exploded perspective view of the backlight module, and FIG. 10 (c) is a perspective view schematically showing how light from the light emitting device propagates in the backlight module. FIG. 11 is a sectional view showing a light emitting device according to the third embodiment of the present invention. 12A and 12B schematically show the operation of the light-emitting device according to the third embodiment of the present invention. FIG. 12A is a cross-sectional view of the light-emitting device, and FIG. ) Is a perspective view showing light emitted from the light emitting device. FIG. 13 is a cross-sectional view showing a light emitting device according to a modification of the third embodiment of the present invention. 14 (a) to 14 (c) schematically show the operation of the light emitting device according to a modification of the third embodiment of the present invention, and FIG. 14 (a) is a sectional view of the light emitting device. FIG. 14B is a perspective view showing light emitted from the light emitting element, and FIG. 14C is a perspective view showing light emitted from the light emitting device. FIG. 15 is a cross-sectional view schematically showing the operation of the light emitting device according to the fourth embodiment of the present invention. FIG. 16 is a schematic cross-sectional view showing a conventional light emitting device.

(First embodiment)
A light emitting device according to a first embodiment of the present invention and a backlight module using the light emitting device will be described with reference to FIGS.

  As shown in FIG. 1A and FIG. 1B, the backlight module 100 is provided, for example, on the light guide plate 90 and a lower end surface (edge) on the lower side of the light guide plate 90 with a space therebetween. A plurality of light emitting devices 1, a reflector 91 provided on a surface (back surface) opposite to the liquid crystal panel 95 (not shown) in the light guide plate 90, and a diffusion plate provided between the light guide plate 90 and the liquid crystal panel 95. 92.

  Each light emitting device 1 is mounted on each holding unit 85 divided into a plurality of parts, and a wiring 86 is connected to the holding unit 85.

  Next, the configuration and operation of the light emitting device 1 and the light guide plate 90 will be described with reference to FIG.

  As shown in FIG. 2A, the light emitting device 1 includes a package 20, a light emitting element (not shown), a transparent optical element 30, and a phosphor layer 35. Outgoing light emitted from a light emitting element described later has an divergence angle between the illuminating device 1 and the divergence angle in the minor axis direction (x axis direction) 62a and the divergence angle in the major axis direction (y axis direction) 62b. It is emitted as white light 62 having a large ratio value.

  As shown in FIG. 2B, in the backlight module 100, when the thickness direction of the light guide plate 90 is the x-axis direction and the longitudinal direction of the lower end surface is the y-axis direction, each light emitting device 1 has the holding portion 85. They are interposed so that the spread angle is large in the y direction and the spread angle is small in the x direction. As a result, as shown in FIG. 2C, the white light 62 emitted from each light emitting device 1 is efficiently incident because the divergence angle is small in the x-axis direction of the light guide plate 90, and the light guide plate 90. Propagate through. On the other hand, since the spread angle of the light emitted from each light emitting device 1 is large in the y-axis direction of the light guide plate 90, the light spreads efficiently in the yz plane direction of the light guide plate 90. The occurrence of light unevenness can be greatly reduced.

  Next, the configuration of the light emitting device 1 will be described with reference to FIG.

  As shown in FIG. 3, the light emitting device 1 according to the first embodiment includes a light emitting element 10, a submount 11 that fixes and holds the light emitting element 10, and a package that fixes and holds the submount 11. 20, a transparent optical element 30 that is fixed to the package 20 and transmits light emitted from the light emitting element 10 to change the optical path, and a phosphor layer 35 formed on the upper surface of the transparent optical element 30. The

  The package 20 is made of a metal such as copper (Cu) or Kovar (Fe / Ni / Co alloy), for example, and is a flat plate-like base material 20a and a mounting surface on the mounting surface 20c of the base material 20a. The base 20b is held perpendicular to the base 20c, at least two leads 20d1 and 20d2, and a cap member 20f fixed on the base member 20a so as to cover the base 20b. The first lead 20d1 is insulated from the base material 20a by an insulating portion 20e made of an insulating material such as glass, and the second lead 20d2 is electrically connected to the base material 20a.

  The light emitting element 10 is fixed to the mounting surface 20c of the base 20b via the submount 11. Further, the light emitting element 10 is electrically connected to the first lead 20d1 via the wire 9, and is electrically connected to the second lead 20d2 via the submount 11, the wire 9 and the base 20b. Yes. The light emitting element 10 is, for example, a semiconductor laser element or a super luminescent diode (SLD) that emits light having a wavelength of 430 nm to 480 nm, and an end face emission type in which emitted light is emitted from one end face of the light emitting element 10. It is a light emitting element. Note that the light emitting element 10 is more preferably an SLD because of low coherence of emitted light.

  A diffraction grating 30a is formed on one surface of the transparent optical element 30 made of a transparent substrate, and the other surface is made of a transparent material such as silicone resin with Ce: YAG (cerium-added yttrium, aluminum, garnet). A phosphor layer 35 made of a material in which phosphor materials such as the above are mixed is formed. The diffraction grating 30a of the transparent optical element 30 is formed on the side facing the light emitting element 10, and is arranged at a predetermined interval, for example, 1.5 mm with respect to the light emitting element 10 with the cap material 20f interposed.

  Next, the operation of the light emitting device 1 will be described with reference to FIG.

  As shown in FIGS. 4A and 4B, the outgoing light 50 emitted from the light emitting element 10 has an elliptical divergence angle having a divergence angle in the minor axis direction 50a and an divergence angle in the major axis direction 50b. Is emitted. At this time, when the light emitting element 10 itself is formed by stacking a plurality of semiconductor layers, the short axis direction 50a coincides with the x axis direction when the stacking direction of the semiconductor layers is the y axis and the emission direction is the z axis. The major axis direction 50b coincides with the y-axis direction.

  As shown in FIGS. 4A to 4C, the outgoing light 50 from the light emitting element 10 is incident on the diffraction grating 30 a of the transparent optical element 30. A part of the incident light is diffracted by the diffraction grating 30a and becomes an outgoing light 60 having a divergence angle larger than that of the incident light, and is incident on the phosphor layer 35. At this time, as shown in FIG. 4C, the light transmitted through the diffraction grating 30a has an divergence angle in the minor axis direction (x-axis direction) 60a and an divergence angle in the major axis direction (y-axis direction) 60b. The emitted light 60 has a large aspect ratio.

  Furthermore, in the present embodiment, the cross-sectional shape of the light emitting end face of the waveguide of the light emitting element 10 has a rectangular shape whose long side is parallel to the extending direction of the grating pattern in the diffraction grating 30a. That is, the light emitting element 10 and the diffraction grating 30a are arranged so that the rectangular shape of the cross section at the light emitting end face of the waveguide is parallel to the extending direction of the grating pattern in the diffraction grating 30a. The light divergence angle in the direction in which the aspect ratio is large can be further increased.

  Next, as shown in FIG. 4A, a part of the incident light that has entered the phosphor layer 35 is, for example, fluorescent light 61 that is yellow light centered at a wavelength of 580 nm by the phosphor of the phosphor layer 35. Is emitted. At this time, the light emitted from the light emitting device 1 is light in which the emitted light 60 and the fluorescent light 61 are mixed. Therefore, by setting the outgoing light 60 to blue light and the fluorescent light 61 to yellow light, pseudo white light 62 can be emitted.

  Next, a method for designing the diffraction grating 30a will be described with reference to FIG.

  For the diffraction grating 30a provided in the transparent optical element 30, in order to increase the value of the aspect ratio of the outgoing light 50, for example, gratings extending in the x-axis direction as shown in FIG. 5A are arranged in the y-axis direction. It is a periodic lattice pattern.

  Here, the change in the radiation angle of the emitted light 50 by the diffraction grating 30a will be described using the calculation results shown in FIGS. 5B and 5C.

  First, the wavelength of the emitted light 50 emitted from the light emitting element 10 is set to 450 nm, and the radiation angle in the air is a half-value width and the divergence angle in the minor axis direction (x-axis direction) 50a as shown in FIG. Is θx = 10 °, and the divergence angle in the major axis direction (y-axis direction) 50b is θy = 30 °. If the pitch of the diffraction grating 30a of the transparent optical element 30 is 0.64 μm, the radiation angle of the first-order diffracted light transmitted through the diffraction grating 30a is ± 50 ° with respect to the incident angle of the incident light. Further, since the light quantity ratio of the first-order diffracted light can be adjusted by the depth of the diffraction grating 30a, when the ratio of the 0th-order diffracted light and the first-order diffracted light is 1: 1, as shown in FIG. The light with the radiation angle distribution is obtained. That is, the x direction can be as narrow as θx = 10 ° and the y direction can be as wide as θy = 120 °. As a result, a light source having a radiation angle characteristic with a very large aspect ratio value can be obtained.

  As described above, according to the first embodiment, by coupling the light emitting device 1 that emits the emitted light 60 having the radiation pattern as shown in FIG. The backlight module 100 with high efficiency and uniform light distribution inside the light guide plate 90 can be manufactured.

  In the present embodiment, the light emitting element 10 is arranged on the pedestal 20b via the submount 11. However, the mounting surface 20c on the pedestal 20b is solder-plated to attach the light emitting element 10 to the pedestal 20b. It is good also as a structure arrange | positioned directly on top. In this case, the submount 11 becomes unnecessary, and as a result, the number of components of the light emitting device 1 can be reduced.

(One modification of the first embodiment)
Hereinafter, a light-emitting device according to a modification of the first embodiment of the present invention will be described with reference to FIG.

  In this modification, the grating pattern of the diffraction grating 30b provided on the transparent optical element 30 is irregularly (randomly) formed. Here, the lattice pattern is irregular includes the case where the interval of the lattice is irregular, that is, the period is irregular, the case where the size of one lattice is irregular, and the like.

  As shown in FIGS. 6A and 6B, the diffraction grating 30b is a grating pattern in which, for example, gratings extending in the x-axis direction are arranged in the y-axis direction, as in the first embodiment. The pattern period is random.

  Here, the change in the radiation angle of the emitted light 50 by the diffraction grating 30b will be described using the calculation results shown in FIGS. 6 (c) and 6 (d).

  First, the wavelength of the outgoing light 50 emitted from the light emitting element 10 is set to 450 nm, and the radiation angle in the air is a half-width and the spread angle in the minor axis direction (x-axis direction) 50a as shown in FIG. Is θx = 10 °, and the divergence angle in the major axis direction (y-axis direction) 50b is θy = 30 °. Assuming that the pitch of the diffraction grating 30b of the transparent optical element 30 is random, the light transmitted through the diffraction grating 30 is a radiation angle distribution in the air represented by a Lambert distribution as shown in FIG. It becomes light with. That is, the x direction can be as narrow as θx = 10 ° and the y direction can be as wide as θy = 120 °. As a result, a light source having a radiation angle characteristic with a very large aspect ratio value can be obtained.

(Second Embodiment)
Hereinafter, a light-emitting device according to a second embodiment of the present invention will be described with reference to FIG. In FIG. 7, the same components as those shown in FIG. 3 are denoted by the same reference numerals.

  As shown in FIG. 7A, the light emitting device 1A according to the second embodiment is provided with a semicylindrical recess 30c instead of the diffraction grating provided on the surface of the transparent optical element 30 on the light emitting element 10 side. ing. Further, the transparent optical element 30 is arranged such that the concave surface, which is the inner surface of the concave portion 30c, has a predetermined distance, for example, 1.5 mm, from the light emitting element 10 with the cap material 20f constituting the package 20 interposed. Further, as shown in FIG. 7B, the concave portion 30c of the transparent optical element 30 is formed so that the central axis of the concave surface coincides with the x-axis direction.

  The light emitting element 10 is arranged on the pedestal 20b via the submount 11 so that the waveguide is parallel to the xz plane. Furthermore, also in this embodiment, the cross-sectional shape of the light emitting end face of the waveguide of the light emitting element 10 has a rectangular shape whose long side is parallel to the central axis direction (x-axis direction) of the recess 30c.

  As described above, according to the second embodiment, the emitted light emitted from the light emitting element 10 has a major axis in the y-axis direction and a minor axis in the x-axis direction, as in the first embodiment. The elliptical shaped outgoing light is emitted. In addition, the light emitting device 1 </ b> A having a larger spread angle aspect ratio value can be realized by the concave surface formed by the concave portion 30 c.

(First Modification of Second Embodiment)
Hereinafter, a light emitting device according to a first modification of the second embodiment of the present invention will be described with reference to FIG.

  The optical element 30A in the light emitting device 1B according to this modification has a surface (upper surface) opposite to the surface on which the concave portion 30c is formed in a convex shape along the shape of the concave portion 30c.

  With this configuration, the same effects as those of the second embodiment can be obtained, and the emitted light refracted by the concave surface formed by the concave portion 30c can be uniformly transmitted through the phosphor layer 35, thereby improving the color rendering of the emitted light. can do.

(Second modification of the second embodiment)
Hereinafter, a light emitting device according to a second modification of the second embodiment of the present invention will be described with reference to FIG.

  In the optical element 30A in the light emitting device 1C according to this modification, a diffraction grating 30a is formed on the concave surface formed by the concave portion 30c. Here, the grating pattern of the diffraction grating 30a is formed so that the striped pattern is parallel to the central axis of the recess 30c.

  With this configuration, the same effect as the first modification of the second embodiment can be obtained, and a concave surface can be formed with a higher degree of freedom in accordance with the outgoing light pattern converted by the concave portion 30c having the diffraction grating 30a. can do.

  In addition, you may form the diffraction grating 30a also in the surface of the recessed part 30c of the transparent optical element 30 shown in FIG.

(Third embodiment)
Hereinafter, a light-emitting device and a backlight module using the same according to a third embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 10A, the light emitting device 1D according to the third embodiment has a large aspect ratio value between the divergence angle in the minor axis direction 62a and the divergence angle in the major axis direction 62b from the light emitting end face. The white light 62 having a divergence angle is output.

  As shown in FIG. 10B, the backlight module 100A according to the third embodiment includes a plurality of light emitting devices 1D, and a plurality of wiring boards each holding and electrically connecting the plurality of light emitting devices 1D. 185 and a light guide plate 90 optically connected to the plurality of light emitting devices 1D.

  On the wiring board 185, electrode pads 186, extraction electrode pads 188, and internal wirings 187 that electrically connect them are formed. Each light emitting device 1 </ b> D is connected to the electrode pad 186 on the lower surface, and is arranged so that the light emitting surface, which is the upper surface, faces the side end surface of the light guide plate 90. Further, the one with the smaller divergence angle of the emitted light (short axis direction 62a) of each light emitting device 1D is arranged parallel to the thickness direction (x-axis direction) of the light guide plate 90, and the one with the larger divergence angle of the emitted light (long) The axial direction 62b) is installed so as to be parallel to the longitudinal direction (y-axis direction) of the light guide plate 90.

  In this way, as shown in FIG. 10C, the white light 62 emitted from each light emitting device 1 </ b> D is efficiently incident on the light guide plate 90 in the x-axis direction where the divergence angle is small, and Propagate through. On the other hand, in the y-axis direction of the light guide plate 90, since the white light 62 emitted from each light emitting device 1D is incident on the light guide plate 90, the light spreads efficiently in the yz plane direction of the light guide plate 90. The occurrence of unevenness of light inside the light guide plate 90 can be greatly reduced.

  The configuration of the light emitting device 1D will be described with reference to FIG.

  As shown in FIG. 11, a light emitting device 1D according to the third embodiment includes a light emitting element 10A, a package 120 that holds the light emitting element 10A in a fixed manner, and is fixed to the package 120. It is composed of a transparent optical element 30B made of a transparent substrate that transmits outgoing light and changes the optical path, and a phosphor layer 35 formed on the upper surface of the transparent optical element 30B.

  The package 120 is made of, for example, a metal material obtained by plating silver (Ag) or the like on the surface of a metal having conductivity, pressability, and high thermal conductivity such as C194 (copper alloy), and includes the first electrode 120a and the second electrode 120a. And an edge portion having a region for forming the insulating portion 120c and the reflective film 120e made of a plastic material such as PA (polyamide), PPA (polyphthalamide), or PPS (polyphenylene sulfide), for example. 120d.

  The insulating part 120c electrically insulates the first electrode 120a and the second conductive plate 120b. A reflective film 120e that forms an angle of 45 ° with respect to the optical axis of the light emitting element is formed on one surface of the edge portion 120d that faces the light emitting element. The reflective film 120e is configured by, for example, a metal film such as silver (Ag), aluminum (Al), or copper (Cu), a dielectric multilayer film, or a combination of a metal film and a dielectric multilayer film. For example, by using a PPA material having a high reflectance at a wavelength of 420 nm to 500 nm for the insulating portion 120c and the edge portion 120d, the reflective film 120e can be made of the same material as the insulating portion 120c and the edge portion 120d. it can.

  The light emitting element 10A is fixed on the first electrode 120a with the submount 11A interposed therebetween and the light emitting end face facing the reflective film 120e. The light emitting element 10 </ b> A is electrically connected to the second electrode 120 b by the wire 9. Also here, the light emitting element 10A is, for example, a semiconductor laser element or a super luminescent diode (SLD) that emits light having a wavelength of 430 nm to 480 nm, and is an end emission type that emits light from one end face of the light emitting element 10A. It is a light emitting element. Further, the cross-sectional shape of the light emitting end face of the waveguide of the light emitting element 10A has a rectangular shape whose long side is parallel to the extending direction of the grating pattern in the diffraction grating 30a.

  Note that it is more preferable to use an SLD for the light emitting element 10A because the SLD has low coherence of emitted light.

  A diffraction grating 30a is formed on the lower surface of the transparent optical element 30B facing the light emitting end face side of the light emitting element 10A and the reflecting film 120e. Here, the grating pattern of the diffraction grating 30a is formed so that the striped pattern is orthogonal to the optical axis of the emitted light. The transparent optical element 30B on which the diffraction grating 30a is formed is fixed on the edge 120d of the package 120 so as to cover the light emitting element 10A with a predetermined distance, for example, 500 μm, from the light emitting element 10A.

  Further, on the surface (upper surface) opposite to the diffraction grating 30a in the transparent optical element 30B, a phosphor layer 35 made of a material obtained by mixing a phosphor material such as Ce: YAG with a transparent material such as silicone resin is formed. Has been.

  Next, the operation of the light emitting device 1D will be described with reference to FIG.

  As shown in FIG. 12A and FIG. 12B, the emitted light 50 emitted from the light emitting element 10A is reflected above the package 120 by the reflective film 120e provided on the package 120, so that the transparent optical Incident on element 30B. A part of the incident light incident on the transparent optical element 30B is diffracted by the diffraction grating 30a provided in the transparent optical element 30B, and becomes an outgoing light 60 having a larger divergence angle than the incident light. Incident light that has passed through the transparent optical element 30B is incident on the phosphor layer 35 on the transparent optical element 30B, and a part of the light incident on the phosphor layer 35 is caused by the phosphor, for example, with a wavelength centering on 580 nm. The fluorescent light 61 that is yellow light is emitted. At this time, the light emitted from the light emitting device 1D is light in which the emitted light 60 and the fluorescent light 61 are mixed. Therefore, the light emitting device 1D can emit white light 62 by using the emitted light 60 as blue light and the fluorescent light 61 as yellow light.

  Here, in the above configuration, the change in the radiation angle of the emitted light 50 from the light emitting element 10A by the diffraction grating 30a is the same as in the first embodiment.

(One Modification of Third Embodiment)
Hereinafter, a light-emitting device according to a modification of the third embodiment of the present invention will be described with reference to FIGS. 13 and 14.

  In the light emitting device 1E according to the present modification, a double-sided emission type semiconductor laser element or a super luminescent diode (SLD) is used as the light emitting element 10B that emits light having a wavelength of 430 nm to 480 nm. Therefore, in the package 120A that holds the light emitting element 10B, the first reflective film 120e1 and the second reflective film 120e2 are formed on both edge portions 120d that face the two light emitting end faces of the light emitting element 10B. ing. In addition, the constituent material of each reflective film 120e1 and 120e2 is equivalent to the reflective film 120e of 3rd Embodiment.

  In this modification, the diffraction grating 30a of the transparent optical element 30B is formed over substantially the entire surface above the first reflective film 120e1, the second reflective film 120e2, and the light emitting element 10B.

  Next, the operation of the light emitting device 1E will be described with reference to FIG.

  As shown in FIGS. 14 (a) and 14 (b), from the light emitting element 10B according to this modification, emitted light 50 emitted from both end faces of the front end face and the rear end face of the waveguide (stripe) 10a, respectively. , 70 are respectively reflected above the package 120A by the first reflective film 120e1 and the second reflective film 120e2 provided on the package 120A, and enter the transparent optical element 30B. A part of each incident light incident on the transparent optical element 30B is diffracted by the diffraction grating 30a provided in the transparent optical element 30B, and becomes outgoing lights 60 and 80 having a divergence angle larger than the incident light. Each incident light transmitted through the transparent optical element 30B is incident on the phosphor layer 35 on the transparent optical element 30B, and a part of the light incident on the phosphor layer 35 is centered at a wavelength of, for example, 580 nm by the phosphor. Are emitted as fluorescent light 61 and 81 which are yellow light. At this time, as shown in FIG. 14C, the light emitted from the light-emitting device 1E is light in which the outgoing lights 60 and 80 and the fluorescent lights 61 and 81 are mixed, and the outgoing lights 60 and 80, respectively. By making blue light and fluorescent light 61 and 81 yellow light, white light 62 and 82 can be emitted.

  Next, the aspect ratio of the emitted light emitted from the light emitting device 1E according to this modification will be described with reference to FIGS. 14 (a) to 14 (c).

  If an SLD is used for the light emitting element 10B, the light amplified in the longitudinal direction by the stripe 10a formed in the light emitting element 10B is emitted as emitted light 50 and 70 from the front end face and the optical end face, respectively. At this time, as shown in FIG. 14B, the outgoing lights 50 and 70 have a short axis direction in the direction parallel to the top surface of the light emitting element 10B, and a long axis direction in the direction perpendicular to the top surface. Is emitted as outgoing light having an elliptical divergence angle.

  As described above, the outgoing lights 50 and 70 emitted from the light emitting element 10B are reflected above the package 120A by the two reflective films 120e1 and 120e2 in the package 120A, and the diffraction gratings 30a and 30a of the transparent optical element 30B are reflected. The light passes through the phosphor layer 35 and is emitted from the light emitting device 1E. At this time, the emitted white lights 62 and 82 are emitted with a larger divergence angle in the major axis direction by the diffraction grating 30a, that is, with a larger aspect ratio value.

(Fourth embodiment)
Hereinafter, a light emitting device and a backlight module using the same according to a fourth embodiment of the present invention will be described with reference to FIG.

  In the light emitting device 1F according to the present embodiment, a double-sided emission type semiconductor laser element or a super luminescent diode (SLD) is used as the light emitting element 10B that emits light having a wavelength of 430 nm to 480 nm. Further, in the package 120A holding the light emitting element 10B, the first reflection type diffraction grating 120f1 and the second reflection type diffraction grating 120f2 are provided at both edge portions 120d facing the two light emitting end faces of the light emission element 10B. Is formed. Each reflective diffraction grating can be transferred, for example, by forming a concavo-convex shape on the mold side in advance when forming both edge portions 120d of the package 120A by molding. It can be obtained by forming a reflective film. At this time, the constituent material of the reflective film constituting each of the reflective diffraction gratings 120f1 and 120f2 is the same as that of the reflective film 120e of the third embodiment. Further, in the present embodiment, the transparent optical element 30B is a flat transparent substrate, and the phosphor layer 35 is formed on the transparent optical element 30B.

  Next, the operation of the light emitting device 1F according to the present embodiment will be described.

  From the light emitting element 10B according to the present embodiment, the first reflected diffraction diffracted light 50 and 70 emitted from the both end surfaces of the front end surface and the rear end surface of the waveguide (stripe) 10a are provided in the package 120A. The light is reflected above the package 120A by the grating 120f1 and the second reflective diffraction grating 120f2, and enters the transparent optical element 30B. At this time, the outgoing lights 50 and 70 become outgoing lights 60 and 80 having a divergence angle larger than that of the incident light when reflected by a reflective diffraction grating, as will be described later. Each incident light transmitted through the transparent optical element 30B is incident on the phosphor layer 35 on the transparent optical element 30B, and a part of the light incident on the phosphor layer 35 is centered at a wavelength of, for example, 580 nm by the phosphor. Are emitted as fluorescent light 61 and 81 which are yellow light. At this time, the light emitted from the light emitting device 1F is light in which the outgoing lights 60 and 80 and the fluorescent lights 61 and 81 are mixed, and the outgoing lights 60 and 80 are blue light, respectively, and the fluorescent lights 61 and 81 are emitted. By making yellow light, white light 62 and 82 can be emitted.

  Next, the aspect ratio of the emitted light emitted from the light emitting device 1F according to the present embodiment will be described.

  Assuming that an SLD is used for the light emitting element 10B, the light amplified in the longitudinal direction by the stripe formed on the light emitting element 10B is emitted as emitted light 50 and 70 from the front end face and the optical end face, respectively. At this time, the outgoing lights 50 and 70 have an elliptical divergence angle in which the divergence angle in the direction parallel to the upper surface of the light emitting element 10B is the short axis direction and the divergence angle in the direction perpendicular to the upper surface is the divergence angle in the major axis direction It is emitted as outgoing light having

  As described above, the outgoing lights 50 and 70 emitted from the light emitting element 10B are reflected above the package 120A by the two reflective diffraction gratings 120f1 and 120f2 in the package 120A, and the transparent optical element 30B and the phosphor. The light passes through the layer 35 and is emitted from the light emitting device 1F. At this time, the emitted white lights 62 and 82 are emitted with a larger divergence angle in the major axis direction by the reflection type diffraction gratings 120f1 and 120f2, that is, with a larger aspect ratio value.

  In such a configuration, each of the reflection type diffraction gratings 120f1 and 120f2 can be formed at the same time when the package 120 is molded. Therefore, the light emitting device 1F can be configured with a simpler configuration.

  In the present embodiment as well, as in the third embodiment, light is emitted only from one end face of the light emitting element 10B, and the reflection type diffraction grating 120f1 is formed only on the reflection face facing the emission end face. It is good.

  The light-emitting device according to the present invention and the backlight module using the light-emitting device can efficiently enter the light emitted from the light-emitting element into the light guide plate, and can make the light distribution in the light guide plate uniform, For example, the present invention is useful for a backlight light source device in a liquid crystal display device or a light emitting device applicable to a panel-shaped illuminator and a backlight module using the light emitting device.

DESCRIPTION OF SYMBOLS 1 Light emitting device 1A Light emitting device 1B Light emitting device 1C Light emitting device 1D Light emitting device 1E Light emitting device 1F Light emitting device 9 Wire 10 Light emitting element 10A Light emitting element 10B Light emitting element 10a Waveguide (stripe)
11 Submount 11A Submount 20 Package 20a Base material 20b Base 20c Mounting surface 20d1 First lead 20d2 Second lead 20e Insulating portion 20f Cap material 30 Transparent optical element 30A Transparent optical element 30B Transparent optical element 30a Diffraction grating 30b Diffraction grating 30c Concave portion 35 Phosphor layer 50 Outgoing light (before diffraction)
50a minor axis direction 50b major axis direction 60 outgoing light (after diffraction)
60a minor axis direction 60b major axis direction 61 fluorescent light 62 white light 70 outgoing light (before diffraction)
80 Outgoing light (after diffraction)
81 fluorescent light 82 white light 85 holding part 86 wiring 90 light guide plate 91 reflecting plate 92 diffuser plate 95 liquid crystal panel 100 backlight module 100A backlight module 120 package 120A package 120a first electrode 120b second electrode 120c insulating part 120d edge Part 120e Reflective film 120e1 First reflective film 120e2 Second reflective film 120f1 First reflective diffraction grating 120f2 Second reflective diffraction grating 185 Wiring substrate 186 Electrode pad 187 Internal wiring 188 Extraction electrode pad

Claims (13)

A light-emitting element made of a semiconductor having a waveguide;
An optical element provided in the propagation direction of the outgoing light from the light emitting element, and having a diffraction grating for receiving the outgoing light;
A light emitting device comprising: a phosphor layer formed on a surface of the optical element opposite to the diffraction grating.   2. The light emitting device according to claim 1, wherein a cross-sectional shape of the light emitting end face of the waveguide is a rectangular shape whose long side is parallel to the extending direction of the grating pattern in the diffraction grating.   The light-emitting device according to claim 1, wherein the diffraction grating has a grating pattern with irregular grating intervals.   3. The light emitting device according to claim 1, further comprising a reflective film that reflects outgoing light from the light emitting element and makes the reflected outgoing light incident on the diffraction grating. The light emitting element is a double-sided emission type light emitting element,
The light emitting device according to claim 4, wherein the reflection film is provided on one light emitting end face side and the other light emitting end face side of the light emitting element. A light-emitting element made of a semiconductor having a waveguide;
An optical element provided in the propagation direction of the emitted light from the light emitting element and having a semi-cylindrical recess for receiving the emitted light;
A light emitting device comprising: a phosphor layer formed on a surface of the optical element opposite to the concave portion.   The light emitting device according to claim 6, wherein the cross-sectional shape of the light emitting end face of the waveguide is a rectangular shape whose long side is parallel to the central axis direction of the concave portion.   8. The light emitting device according to claim 6, wherein the optical element has a surface opposite to the surface on which the concave portion is formed, in a convex shape along the concave portion. 9.   The light-emitting device according to claim 6, wherein a diffraction grating is provided in the concave portion of the optical element.   The light emitting device according to any one of claims 1 to 9, wherein the light emitting element is a semiconductor laser element or a super luminescent diode. A light emitting device according to any one of claims 1 to 10,
A backlight module comprising: a light guide plate that receives light emitted from the light emitting device on a side surface thereof.   The backlight module according to claim 11, wherein the cross-sectional shape of the light emitting end face of the waveguide of the light emitting element is a rectangular shape whose short side is parallel to the in-plane direction of the main surface of the light guide plate.   The backlight module according to claim 11, wherein the light emitting element is a semiconductor laser element or a super luminescent diode.

Images