JP4642054B2 - Surface emitting device - Google Patents

Description

  The present invention relates to a surface light emitting device, and more particularly to an edge light type surface light emitting device.

  Conventionally, as a surface light emitting device suitably used for a backlight of a liquid crystal display device or the like, light is incident from a side end surface of a light guide plate made of a transparent parallel plate or a wedge-shaped flat plate, and the light is emitted in a planar shape. A so-called edge light type surface emitting device is widely used.

  By the way, the light traveling in the light guide plate repeats many reflections and refractions. Even in the case of reflection using an ideal metal surface, it usually involves an energy loss of about 10 to 15% per reflection, so the light energy is usually less than half after only a few reflections. End up. However, since the edge light type surface light emitting device uses total reflection caused by the difference in refractive index between the inside and outside of the light guide plate (refractive index interface), there is no energy loss due to reflection. That is, the light once incident on the light guide plate can reach the opposite side of the incident end without being attenuated if there is no midway absorption. This is the reason why the surface light emitting device using the light guide plate is practical.

  Conventionally, a CCFL (Cold Cathode Fluorescent Lamp, cold cathode tube) has been widely used as a light source of a surface light emitting device using such a light guide plate. In addition, in recent years, a form in which a plurality of LEDs (Light Emitting Diodes, light emitting diode elements) are arranged on an incident surface has appeared (for example, see Patent Document 1).

  CCFL is a very thin fluorescent tube with a diameter of several millimeters, and has rapidly developed in recent years with the development of light guide plates. The light emission principle of a cold cathode tube is basically the same as that of an ordinary fluorescent tube (hot cathode tube), but since the electrode has no filament, the structure is simple and suitable for reducing the diameter. CCFL emits light linearly. Therefore, if the CCFL is arranged along the longitudinal direction of the side end face of the light guide plate, more light emitted from the CCFL can be incident on the light guide plate from the side end face. Therefore, the CCFL is an edge light type surface emitting device. Suitable as a light source. However, since the electrodes are not heated and field emission is used, the discharge voltage is very high (300 to 700 V) compared to the hot cathode tube. Another disadvantage is the use of mercury.

On the other hand, LEDs that have been increasingly used in recent years do not use mercury like cold cathode fluorescent lamps, and have advantages such as a significantly low operating voltage (that is, light emission at a low voltage). On the other hand, since the amount of light per one LED element is small, a plurality of elements are required, which is currently expensive. Further, when the size is increased, the power consumption becomes larger than that of the cold cathode tube. Thus, both have merits and demerits.
JP 2006-294560 A

  However, CCFL and LED have a common problem that the light use efficiency is low when light is incident on the light guide plate. That is, in the case of CCFL, since it is an omnidirectional light source, it is impossible to make all light emitted from CCFL incident on the light guide plate without causing energy loss. Even if a part of the light that does not go to the light guide plate is redirected to the light guide plate by changing its direction with a metal reflecting mirror or the like, an energy loss occurs at the time of reflection. In the case of an LED, for example, it is possible to emit light having directivity to some extent by concentrating the light by molding it with a resin in a bullet shape, but all of the light emitted from the LED in all directions It is difficult to collect light without leakage. Further, the LED is a point light source, and light is emitted and diffused in a circular shape, and therefore, there is a case where all the light emitted from the LED cannot be incident particularly in the thickness direction of the light guide plate.

  Therefore, a main object of the present invention is to provide a surface light emitting device capable of improving the light use efficiency.

  A surface emitting device according to the present invention includes an edge emitting semiconductor laser element having a laminated structure including a light emitting layer. In addition, a light guide member having a light receiving end face opposed to the light emitting surface of the semiconductor laser element is provided. Moreover, the cross-sectional shape of the light guide member in the direction along the light receiving end surface has a longitudinal direction, and the semiconductor laser element is arranged so that the lamination direction of the laminated structure is along the longitudinal direction.

  Here, the light receiving end surface is a side end surface of the light guide member (a facet of the plate-like body) and is a surface on which the laser light emitted from the semiconductor laser element is incident. The laser light may be incident on one of the side end surfaces of the light guide member, or may be incident on a plurality of surfaces. That is, the light receiving end surface may be one surface or a plurality of surfaces. The light receiving end face is not limited to a flat surface, but may be any shape such as a curved surface, a surface having irregularities, or a surface having serrated jagged edges. The cross section in the direction along the light receiving end face is a cross section of the light guide member that is substantially orthogonal to the optical axis of the laser beam (for example, forms an angle of 80 ° to 100 ° with respect to the optical axis of the laser beam). Say. The laser light emitted from the semiconductor laser element has a belt-like spread as will be described later, and the path of the laser light having a spread angle of 0 ° is referred to as an optical axis of the laser light.

  In addition, when a two-dimensional orthogonal coordinate system (XY coordinate system) is considered in the cross section of the light guide member in the direction along the light receiving end surface, the maximum value in the X direction of the diameter of the cross section (passing length) is When larger than the maximum value in the Y direction, the X direction becomes the longitudinal direction. That is, in the cross section of the light guide member, when the diameter of the cross section in one direction is larger than the diameter of the cross section in the direction orthogonal to the one direction, the one direction is referred to as the longitudinal direction.

  In the above surface light emitting device, the light emitting layer preferably has a light emitting portion for emitting laser light on the light emitting surface. The ratio value obtained by dividing the dimension of the light emitting part in the width direction perpendicular to the stacking direction by the dimension of the light emitting part in the stacking direction is 50 or more. Here, the light emitting layer is an active layer in the semiconductor laser element, and the light emitting portion is a portion of the active layer from which laser light is oscillated and emitted.

  Preferably, a light reflecting member is provided on the opposite side of the light guide member from which light is emitted from the light guide member.

  Preferably, the light reflecting member includes a phosphor that absorbs laser light emitted from the semiconductor laser element and emits light having a wavelength different from the wavelength of the laser light.

  Preferably, at least one of the light receiving end surface and the end surface of the light guide member opposite to the light receiving end surface absorbs laser light emitted from the semiconductor laser element, and emits light having a wavelength different from the wavelength of the laser light. A phosphor layer is provided that emits.

  Preferably, the light receiving end face is provided at a corner of the light guide member. A phosphor layer that absorbs the laser beam emitted from the semiconductor laser element and emits light having a wavelength different from the wavelength of the laser beam is provided on the end surface of the light guide member excluding the end surface that forms the corner. .

Preferably, the light guide member is made of a transparent material.
Preferably, the phosphor layer that absorbs the laser beam emitted from the semiconductor laser element and emits light having a wavelength different from the wavelength of the laser beam on the emission surface of the light guide member from which light is emitted from the light guide member Is provided.

  Preferably, an optical film capable of transmitting laser light and reflecting light having a wavelength different from that of the laser light is formed on the light receiving end face.

  Preferably, at least a part of the end face of the light guide member other than the light receiving end face is provided with an end face light reflecting portion that reflects light.

  In the surface emitting device according to the present invention, the semiconductor laser element and the light guide member are arranged so that the stacking direction of the stacked structure of the semiconductor laser elements is along the longitudinal direction of the cross section along the light receiving end face of the light guide member. . Therefore, the longitudinal direction of the light in which the laser light emitted from the semiconductor laser element spreads in a band shape can be aligned with the longitudinal direction of the cross-sectional shape of the light guide member. Therefore, almost all of the laser beam spreading in a band shape can be incident on the light receiving end face of the light guide member arranged to face the light emitting surface of the semiconductor laser element. Since almost all of the laser light emitted from the semiconductor laser element can be incident on the light guide member, it is possible to improve the use efficiency of the light emitted from the light source and to obtain a surface emitting device with improved luminous intensity.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is an exploded perspective view of the surface light emitting device according to the first embodiment. 2 is a cross-sectional view taken along line II-II shown in FIG. 1 in a state where the surface light emitting device is assembled. As shown in FIGS. 1 and 2, the surface light emitting device 1 includes a light guide plate 2 as a light guide member. The light guide plate 2 is preferably made of a transparent material such as acrylic resin, for example, but any material may be used as long as it has a light transmitting property.

  The light guide plate 2 is formed in a planar rectangular plate shape. The semiconductor laser element 101 that is a light source of the surface light emitting device 1 is disposed so as to face the end surface 2c that is one of the side end surfaces of the rectangular light guide plate 2. The end face 2 c of the light guide plate 2 in the first embodiment is a light receiving end face facing the light emitting face of the semiconductor laser element 101. On the side of the end face 2c of the light guide plate 2, there is provided a phosphor layer 3 that absorbs the laser light emitted from the semiconductor laser element 101 and emits light having a wavelength different from the wavelength of the laser light.

  A surface 2 a that is a wide surface that is not a side end surface of the rectangular light guide plate 2 is an emission surface from which light is emitted from the light guide plate 2. On the surface 2a side of the light guide plate 2, a resin that diffuses light emitted from the light guide plate 2 is coated, and a diffusion sheet 5 is formed as a diffusion member for diffusing the light into a more uniform surface light source. ing. In addition, the light emitted from the light guide plate 2 on the side opposite to the front surface 2a is reflected on the back surface 2b side, and the light emitted in the opposite direction to the light exit surface is reflected and guided to the light exit surface side, thereby reducing the loss of light and increasing the luminance. A reflecting sheet 4 as a light reflecting member is provided for improvement.

  The light guide plate 2, the phosphor layer 3, the reflection sheet 4, the diffusion sheet 5, and the semiconductor laser element 101 are accommodated in the case 6. The case 6 is formed, for example, by resin molding into a flat, substantially box shape having an upper surface opened. By covering the case 6 with the cover 7, the light guide plate 2 and the like housed in the case 6 are fixed and held. The cover 7 is formed with a rectangular opening 7a through which the diffusion sheet 5 is interposed to expose the surface 2a that is the exit surface to the outside. The case 6 and the cover 7 constitute a bezel, which is a frame (frame portion) around the surface light emitting device.

  3 and 4 are schematic views showing the arrangement of the light guide plate with respect to the laser light emitted from the semiconductor laser element. 3 and 4 show a state in which the laser beam 130 is emitted from the semiconductor laser element 101, passes through the phosphor layer 3, and the laser beam 130 is incident on the end surface 2c of the light guide plate 2 that is the light receiving end surface. FIG. 3 shows the same state from different angles using oblique projection and FIG. 4 using isometric projection. In FIG. 4, the reflection sheet 4 and the diffusion sheet 5 shown in FIG. 3 are omitted. With reference to FIGS. 3 and 4, the behavior of the laser beam 130 emitted from the semiconductor laser element 101 inside the light guide plate 2 will be described.

  As shown in FIGS. 3 and 4, the laser light 130 oscillated from the semiconductor laser element 101 has a radiation characteristic that spreads in a band shape. In the end face 2c of the light guide plate 2, the laser beam 130 has a longitudinal direction of the belt-like spread along the long side direction of the rectangular shape of the end face 2c, and a short side direction of the belt-like spread in the short side direction of the rectangular shape of the end face 2c. Then, the light enters the light guide plate 2 through the phosphor layer 3.

Here, when the refractive index of the light guide plate 2 is n and the periphery of the light guide plate 2 is air (refractive index = 1), the critical angle of light on the front surface 2a or the back surface 2b of the light guide plate 2 (when total reflection occurs) The minimum incident angle) θc satisfies the relationship θc = sin ⁻¹ (1 / n). That is, the light reflected by the front surface 2a or the back surface 2b of the light guide plate 2 with a reflection angle equal to or smaller than an angle satisfying θc = sin ⁻¹ (1 / n) is totally reflected.

  When the light guide plate 2 is a rectangular plate and the angle between the light receiving end surface and the front surface 2a and the back surface 2b is a right angle, if the incident angle of light at the light receiving end surface is α, the following relational expression is obtained from Snell's law: Is established.

sin α = n · sin (π / 2−θc) = n · cos θc
Substituting θc = sin ⁻¹ (1 / n) into the above equation,
sin α = √ (n ² −1)
The above formula is satisfied when 1 <n ≦ √2 is satisfied, and when the value of n is within this range, the incident satisfies α <sin ⁻¹ (√ (n ² −1)). The light incident on the light guide plate 2 at the corner is totally reflected on the front surface 2a and the back surface 2b. When n> √2, the light incident on the light guide plate 2 is totally reflected on the front surface 2a and the back surface 2b regardless of the incident angle α. That is, when the light guide plate as described above is formed using a material satisfying n> √2 as the refractive index n of the light guide plate 2, all the light once incident on the light guide plate 2 can be totally reflected.

  The laser light that has entered the light guide plate 2 while satisfying the condition related to the incident angle α is propagated through the light guide plate 2 while being totally reflected by the front surface 2 a and the back surface 2 b of the light guide plate 2. When the exit surface of the light guide plate 2 is the end surface 2d that is the side end surface opposite to the light receiving end surface, the laser light incident on the light guide plate 2 is reflected by the light guide plate 2 due to the difference in refractive index inside and outside the light guide plate 2. Internally reflected to reach the exit surface. However, for example, when the exit surface of the light guide plate 2 is the surface 2 a that is not the side end surface of the light guide plate 2, the laser light is totally reflected inside the light guide plate 2, so that the light is not emitted from the exit surface.

  In such a case, a reflection sheet 4 as a light reflecting member is provided on the back surface 2b opposite to the front surface 2a, which is an exit surface from which light is emitted from the light guide plate 2, and is guided to the exit surface side. . By providing the reflection sheet 4, the light traveling toward the back surface side of the light guide plate 2 is reflected and guided to the front surface 2 a side. For example, the reflection angle of the laser beam on the back surface 2b side of the light guide plate 2 is changed by forming a light scattering projection on the reflection sheet 4 or providing a density gradient, and the laser beam is reflected on the front surface 2a side. Can be made.

  The laser light is emitted to the outside as indicated by an arrow VL from the surface 2a which is an emission surface from which light is emitted from the light guide plate 2. A display panel (not shown) is disposed on the outer surface 2a side of the light guide plate 2 so that light emitted from the surface 2a of the light guide plate 2 enters the display panel as a backlight. In this way, the surface light emitting device 1 can be used as, for example, an edge light type backlight of a liquid crystal display.

  As shown in FIGS. 2 to 4, in the surface light emitting device 1, the phosphor layer 3 is provided on the end surface 2 c side of the light guide plate 2 that is the light receiving end surface. The laser beam 130 enters the light guide plate 2 through the phosphor layer 3. The phosphor layer 3 contains a phosphor that absorbs the laser beam 130 emitted from the semiconductor laser element 101 and emits light having a wavelength different from the wavelength of the laser beam 130. Light of any color can be emitted from the light guide plate 2 by a phosphor that receives the laser light 130 and emits light of a predetermined color.

For example, the phosphor layer 3 can include three types of phosphors that receive laser light 130 having a single wavelength emitted from the semiconductor laser element 101 and emit red, green, and blue light. For example, when the wavelength of the laser beam 130 is 405 nm, the phosphor layer 3 includes CaAlSiN ₃ : Eu ²⁺ as a red phosphor, β-SiAlON: Eu ^{2+ as} a green phosphor, and LaSiAlON: Ce ³⁺ as a blue phosphor. Can be. By exciting these phosphors with the semiconductor laser element 101, a surface light emitting device 1 that emits white light with good color rendering (that is, a difference in color appearance when viewed with sunlight) is realized. can do. Since the phosphor layer 3 is provided on the end surface 2c side having a small surface area, the necessary amount of the phosphor can be reduced.

  Next, the arrangement of the semiconductor laser element 101 based on the structure of the semiconductor laser element 101 and the radiation characteristics of the laser beam will be described. The semiconductor laser element 101 is an edge emitting type having a laminated structure including a light emitting layer. FIG. 5 is a schematic diagram showing the semiconductor laser element viewed from the end surface side opposite to the light receiving end surface of the light guide plate. As can be seen from FIG. 5, the semiconductor laser element 101 is disposed so that the stacking direction of the semiconductor layers constituting the semiconductor laser element 101 is along the longitudinal direction of the cross section of the rectangular light guide plate 2.

  In this semiconductor laser device 101, a semiconductor laser chip 103 manufactured by epitaxially growing an InGaN / AlGaN-based semiconductor layer on a GaN substrate is mounted on a stem 105 with a submount 104 interposed. The wavelength at which the laser light oscillates from the semiconductor laser element 101 can be arbitrarily adjusted by appropriately adjusting the composition and thickness of the semiconductor layer such as the light emitting layer. For example, a blue semiconductor laser element 101 that oscillates at a wavelength of 445 nm can be obtained.

  FIG. 6 is a schematic diagram showing a chip portion of the semiconductor laser element. As shown in FIG. 6, the semiconductor laser chip 103 is connected to electrode pins (not shown) of the stem 105 with metal wires 106 and 107 and terminals 108 and 109 interposed therebetween. In addition, the semiconductor laser chip 103 includes six stripes (resonators) in one chip in order to extract high output light as a light source. One stripe has a width of 10 μm and a resonator length of 400 μm.

FIG. 7 is a perspective view of one stripe portion constituting the semiconductor laser device, and is an enlarged view of a region VII shown in FIG. As shown in FIG. 7, the semiconductor laser chip 103 includes a substrate 110 made of n-type GaN, a buffer layer 111 made of n-type GaN, a lower cladding layer 112 made of n-type AlGaN, and an active layer 113 made of multiple quantum wells of InGaN. , An upper cladding layer 114 made of p-type AlGaN, and a contact layer 115 made of p-type GaN. The semiconductor laser chip 103 includes a p-side electrode 116 made of Pd, an n-side electrode 117 made of Hf / Al, an insulating film 118 made of SiO ₂ , an extraction electrode 119 made of Au, a pad electrode 120 made of Au, and a fusing metal film. A layer 121 and a groove 122 that electrically separates the stripes are provided. When a direct current is passed through the semiconductor laser element 101 through the electrode pin of the stem 105, laser oscillation is started at a wavelength of 445 nm at a threshold current of 0.9A. For example, when the driving current is 3A, an optical output 3W can be obtained.

  FIG. 8 is a schematic diagram showing a radiation characteristic of light emitted from the semiconductor laser element. The stacking direction of the semiconductor layers having a stacked structure is indicated by a double arrow LD. As shown in FIG. 8, the light emitting portion 131 from which the laser beam 130 is emitted on the light emitting surface of the semiconductor laser element 101 is formed horizontally long. The light emitting portion 131 in the width direction orthogonal to the stacking direction can be formed so that the ratio value obtained by dividing the size of the light emitting portion 131 in the stacking direction by 50 or more. Here, the dimension of the light emitting portion 131 in the stacking direction is the thickness of the active layer 113 of the semiconductor laser element 101. For example, if the thickness of the light emitting part 131 is 50 nm and the width is 2.5 μm, the value of the ratio is 50. For example, the value of the ratio may be set to 100, assuming that the light-emitting portion 131 has a thickness of 50 nm and a width of 5 μm. The semiconductor laser device 101 in which the ratio of the dimension in the width direction to the dimension in the stacking direction of the light emitting unit 131 is 50 or more (that is, having the stripe-shaped light emitting unit 131) is a so-called broad area (BA) type semiconductor laser. Constitute.

  The light emitted from the semiconductor laser element 101 has extremely high directivity. That is, the laser beam 130 emitted from the semiconductor laser element 101 has a property of going straight in a certain direction. The radiation characteristic of the laser beam 130 is indicated by an FFP (Far Field Pattern) indicating the shape and intensity distribution of the laser beam 130 measured at a position several cm or more away from the light emitting surface.

  In the BA type semiconductor laser device 101, since the light emitting part 131 is horizontally long and the vertical space is narrow, the light emitted from the light emitting part 131 spreads in such a way as to wrap around by the diffraction action. Therefore, the spread of the emitted laser beam 130 is larger in the vertical direction (semiconductor layer stacking direction) where the exit (light emitting portion 131) is narrower than in the lateral direction (width direction) where the exit is wide. Due to the diffraction effect of the light, the radiation characteristic of the laser beam 130 emitted from the BA type semiconductor laser element 101 has a large spread angle of the laser beam 130 in the stacking direction of the semiconductor laser and spread in the width direction perpendicular to the stacking direction. The angle is small and it becomes a band. For example, the half-value angle of the laser beam 130 when the driving current is 3A is 20 ° in the stacking direction of the semiconductor layers and 7 ° in the width direction.

  That is, the radiation characteristic of the laser light 130 emitted from the edge-emitting semiconductor laser element 101 is a strip shape that is long in the stacking direction of the stacked structure of the semiconductor layers. The laser beam 130 emitted from the semiconductor laser element 101 has a characteristic that it is relatively large in the stacking direction of the semiconductor layers and relatively small in the width direction. Therefore, on the surface parallel to the light emitting surface of the semiconductor laser element 101, the ratio of the dimension of the laser beam 130 in the stacking direction of the semiconductor layers divided by the dimension of the laser beam 130 in the width direction is as follows. Grows as you move away from

  Therefore, in the semiconductor laser element 101 that emits such a belt-shaped laser beam 130, the stacking direction of the semiconductor layers of the semiconductor laser chip 103 is aligned with the longitudinal direction of the end face 2c of the light guide plate 2 as shown in FIG. Install as follows. That is, the semiconductor laser element 101 and the light guide plate 2 are arranged so that the stacking direction of the stacked structure of the semiconductor laser elements 101 is along the longitudinal direction of the cross section along the light receiving end face (end face 2c) of the light guide plate 2 having the rectangular plate shape. Deploy. Thereby, the laser beam 130 irradiated to the light guide plate 2 has a shape along the cross section of the light guide plate 2.

  In other words, in Embodiment 1, the light guide plate 2 is a flat plate having a rectangular shape, and the end surface 2c, which is the light receiving end surface, is a side end surface on the short side of the rectangular plate shape of the light guide plate 2, and therefore the end surface 2c is rectangular. It is formed to make. The cross-sectional shape of the light guide plate 2 along the end surface 2c is also rectangular. Therefore, in Embodiment 1, since the cross-sectional shape of the light guide plate 2 along the end surface 2c is a rectangle, the long side of the rectangle is the longitudinal direction. The arrangement of the semiconductor laser element 101 and the light guide plate 2 is adjusted so that the stacking direction of the semiconductor layers having the stacked structure is along the longitudinal direction.

  In this way, by aligning the arrangement of the BA type semiconductor laser elements 101, the longitudinal direction of the light in which the laser light 130 emitted from the semiconductor laser elements 101 spreads in a band shape is aligned with the longitudinal direction of the cross-sectional shape of the light guide plate 2. be able to. Therefore, almost all of the laser beam 130 spreading in a band shape can be incident on the light receiving end face of the light guide plate 2 disposed to face the light emitting surface of the semiconductor laser element 101. In the surface emitting device 1 using the semiconductor laser element 101 as a light source, almost all of the laser light 130 emitted from the semiconductor laser element 101 can be incident on the light guide plate 2. The surface light emitting device 1 can be obtained in which the light use efficiency is improved and the luminous intensity is improved with respect to the cathode tube and the LED.

  Since the laser light 130 having a shape along the cross section of the light guide plate 2 is irradiated to the light guide plate 2, the laser light 130 propagates inside the light guide plate 2 so as to spread in the longitudinal direction of the cross section of the light guide plate 2. . And the laser beam is reflected by the action of the reflection sheet 4 to the surface 2a side which is an emission surface. Light that is reflected by the reflection sheet 4 and reaches the surface 2 a at an incident angle that can be emitted to the outside is diffused by the diffusion sheet 5. Therefore, it is possible to provide a uniform surface light source that can emit light uniformly from the entire surface 2a, which is the emission surface.

  Here, by adjusting the spread angle of the laser beam 130 spreading in a strip shape and the distance from the semiconductor laser element 101 to the light guide plate 2, the laser beam 130 is spread over a wider range of the end surface 2c that is the light receiving end surface. It is desirable to enter the light guide plate 2. In this way, more uniform light can be emitted from the entire emission surface of the light guide plate 2. For example, when the surface 2a which is a wide surface which is not a side end surface of the plate-shaped light guide member is an emission surface, if the area where the laser beam 130 is not incident on the light receiving end surface (end surface 2c) is large, the light guide plate 2 This is because the surface emitting light tends to be non-uniform. If the semiconductor laser element 130 is disposed away from the light guide plate 2, the surface emitting device 1 is increased in size. Therefore, the spread angle of the laser light 130 is adjusted by adjusting the thickness of the semiconductor layer and the ridge width. Is more desirable.

  The amount of the laser beam 130 included in the range within twice the half-value angle of the laser beam 130 is 98% or more of the total emitted light. For this reason, the light utilization efficiency can be further improved by adjusting the light receiving end face to include a range that is within twice the half-value angle of the laser beam 130. Since the laser beam 130 has a large spread in the stacking direction of the semiconductor layers (that is, the direction orthogonal to the thickness direction of the light guide plate 2 at the light receiving end face), the laser beam 130 is adjusted by adjusting the half-value angle of the laser beam 130 with respect to the stacking direction. 130 can be spread over a wider range of the light receiving end face. The half-value angle is a parameter indicating the directivity of light, and is defined as a deviation angle from the optical axis at a point where the light emission intensity becomes half of the peak value.

  Depending on the half-value angle of the laser beam 130 and the distance between the semiconductor laser element 101 and the light guide plate 2, the area irradiated with the laser beam 130 on the light receiving end face is naturally determined. On the other hand, the thickness direction dimension of the light guide plate 2 is on the order of mm, the thickness of the light emitting layer of the semiconductor laser element 101 is about 0.1 μm at the maximum, and the laser light 130 spreads in the thickness direction of the light guide plate 2. Since the angle is about 5 °, it is considered that almost all of the laser light 130 can be incident on the light receiving end face in the thickness direction of the light guide plate 2.

  Moreover, the current density and the light density of the light emitting part 131 can be reduced by using the semiconductor laser element 101 as the BA type and increasing the area of the light emitting part 131. When the area of the light emitting unit 131 is small, if a large current is passed, the semiconductor laser element 101 may be destroyed due to an excessive current density. By adopting the BA type, the current density of the light emitting unit 131 is reduced, and a large current can be passed through the semiconductor laser. Therefore, the output of the semiconductor laser as the light source of the surface emitting device 1 can be increased.

  In the BA type semiconductor laser device 101, by increasing the widthwise dimension (ridge width) of the light emitting portion 131, the emitted laser light 130 is not in a single mode, and higher order (second order or higher). There may be a plurality of points where the mode laser beam 130 is oscillated and the light intensity increases. When used for communication, signal reading, and the like, when the higher-order mode laser beam 130 is oscillated, the point of high light intensity becomes unstable and the loss increases, which may be a problem. . However, in the surface light emitting device 1, a diffusion sheet 5 as a diffusion member that is disposed on the front surface 2a side of the light guide plate 2 and diffuses light, and a reflection sheet 4 as a light reflection member that is disposed on the back surface 2b side that is not the emission surface. According to the design of, it is possible to cope with the uniform emission of light. Therefore, even if the higher-order mode laser light 130 is oscillated from the BA type semiconductor laser element 101, it is considered that there is no problem.

(Embodiment 2)
FIG. 9 is a schematic diagram illustrating a configuration of the surface light emitting device according to the second embodiment. The surface light emitting device of the second embodiment and the surface light emitting device of the first embodiment described above basically have the same configuration. However, the second embodiment is different from the first embodiment in that the installation position of the phosphor layer 3 is as shown in FIG. Specifically, as shown in FIG. 9, the phosphor layer 3 is provided on the surface 2 a of the light guide plate 2, which is an emission surface from which light is emitted from the light guide plate 2.

  The phosphor receives incident light and emits light in all directions. In the first embodiment, the phosphor layer 3 is provided on the end face 2c that is the light receiving end face. However, if the phosphor layer is provided on the light receiving end face of the light guide plate 2, light emitted from the phosphor to the semiconductor laser element side is lost in energy. As a result, the light utilization efficiency may decrease. Therefore, as shown in FIG. 9, if the phosphor layer 3 is arranged on the surface 2a of the light guide plate 2 that is the exit surface, a part of the light emitted by the phosphor is emitted to the outside as it is. A part of the light emitted to the light guide plate 2 side is reflected by the back surface 2b of the light guide plate 2 or the reflection sheet 4 (see FIG. 3), guided to the front surface 2a side, and emitted to the outside. Therefore, since the light emitted from the phosphor layer 3 can be efficiently emitted to the outside, the light use efficiency can be further improved.

(Embodiment 3)
FIG. 10 is a schematic diagram illustrating a configuration of the surface light emitting device according to the third embodiment. The surface light-emitting device of Embodiment 3 and the surface light-emitting device of Embodiment 1 described above basically have the same configuration. However, the third embodiment is different from the first embodiment in that the installation position of the phosphor layer 3 is a position as shown in FIG. Specifically, as shown in FIG. 10, the phosphor layer 3 is provided on the end surface 2d side opposite to the end surface 2c of the light guide plate 2 which is a light receiving end surface.

  As in the first embodiment, since the phosphor layer 3 is provided on the side of the end face 2d that is the side end face of the light guide plate 2, the surface area of the light guide plate 2 on which the phosphor layer 3 is provided is reduced. The required amount of phosphor can be reduced. Moreover, in the structure of Embodiment 1 and 3 in which the fluorescent substance layer 3 is provided in the end surface of the light-guide plate 2, the light-guide plate 2 is made into a transparent material and the reflective sheet 4 is arrange | positioned at the back surface 2b side of a light-guide plate. Thus, a configuration capable of illuminating the liquid crystal by reflection of external light can be realized. As a transparent material for forming the light guide plate 2, inorganic glass such as quartz, acrylic resin, polycarbonate resin, cycloolefin resin, or the like can be used.

  For example, in a sufficiently bright environment such as outdoors during the day, if the liquid crystal can be illuminated by reflection of outside light, it is not necessary to always turn on the liquid crystal backlight of the portable device. That is, if the backlight is turned on only in a dark place, power saving and a longer lifetime of the backlight can be achieved.

  In the configuration in which the phosphor layer 3 shown in FIG. 10 is provided only on the end surface 2d of the light guide plate 2, the back surface of the light guide plate 2 is in a path where the laser light incident from the end surface 2c that is the light receiving end surface reaches the end surface 2d. The case where it is guide | induced to the surface 2a by the reflection member provided in the side can be considered. That is, there is a possibility that monochromatic light of laser light is emitted from the surface 2a. In order to prevent this, for example, a filter for cutting the wavelength of the laser beam can be provided on the surface 2a side. Further, for example, the arrangement of the phosphor layer 3 can be a combination of the end face 2c and the end face 2d, or a combination of the surface 2a and the end face 2d. When the phosphor layer 3 is used in combination, the phosphor concentration can be distributed. For example, the phosphor concentration on the end face 2c side can be reduced and the phosphor concentration on the end face 2d side can be increased. In this case, only a part of the laser light is turned into white light on the phosphor layer 3 on the end face 2c side where the phosphor concentration is low. However, laser light that has not been whitened by the phosphor layer 3 on the end face 2c side can be completely whitened by the phosphor layer 3 on the end face 2d side. Therefore, white light can be efficiently obtained from monochromatic light of laser light.

(Embodiment 4)
FIG. 11 is a schematic diagram illustrating a configuration of the surface light emitting device according to the fourth embodiment. The fourth embodiment is different from the second embodiment described above in that the semiconductor laser element 101 is arranged as shown in FIG. Specifically, as shown in FIG. 11, the semiconductor laser element 101 is not arranged to face the side end surface of the light guide plate 2 constituting the side portion of the rectangular plate shape, but is a corner portion of the light guide plate 2 having the rectangular plate shape. Is arranged. An end face 2c which is a light receiving end face is formed by cutting out a part of the corner of the rectangular plate shape.

  In order to emit uniform light from the exit surface of the light guide plate 2, it is preferable that the laser light incident on the light guide plate 2 propagates to all regions inside the light guide plate 2. Therefore, when the semiconductor laser element is arranged so as to face the side of the rectangular plate shape, in order to emit uniform light from the emission surface of the light guide plate 2, the laser light is incident before entering the light guide plate 2. The light spreads out in a strip shape outside the light guide plate 2, and the laser beam needs to be incident from a wide area of the light receiving end face. However, when the semiconductor laser element 101 is disposed at the corner of the light guide plate 2, the laser light emitted from the semiconductor laser element 101 is incident on the light guide plate 2 from the corner, so that the laser light is generated inside the light guide plate 2. Can spread to reach the end face 2e. In this way, since the laser light propagates to all areas inside the light guide plate 2, uniform light can be emitted from the emission surface. Therefore, the semiconductor laser element 101 can be disposed closer to the light guide plate 2.

  For example, in the configuration of the first embodiment described with reference to FIG. 3, when the semiconductor laser element 101 is arranged close enough to contact the light guide plate 2, the light is spread over a wider range of the end surface 2 c that is the light receiving end surface. For this purpose, the laser beam 130 needs to spread at a half-value angle of approximately ± 90 °. On the other hand, when the semiconductor laser element 101 is disposed at the corner of the light guide plate 2, it is not necessary for the laser light to spread greatly outside the light guide plate 2. For example, in the configuration shown in FIG. 11, the semiconductor laser element 101 is disposed at a corner portion forming a right angle of the light guide plate 2 having a rectangular plate shape. In this case, the spread of the laser light in the longitudinal direction of the cross-sectional shape of the light guide plate 2 along the end surface 2c (that is, the direction orthogonal to the thickness direction of the light guide plate 2 in the cross section) is a half-value angle ± 45 °. It will be good.

  As the half-value angle is smaller, parameters such as the thickness of the semiconductor layer and the ridge width are easily adjusted when the semiconductor laser device 101 is manufactured. Therefore, the configuration in which the semiconductor laser element is disposed at the corner portion can further improve the manufacturing yield compared to the configuration in which the semiconductor laser element is disposed to face the side portion of the light guide member. . Note that the ridge width is substantially the same as the dimension in the width direction of the light emitting portion, and is the width W shown in FIG. The configuration in which the semiconductor laser element 101 is arranged at the corner of the light guide plate 2 is such that the planar shape of the light guide plate 2 is a square or a rectangle close thereto (that is, the aspect ratio (long side / short side ratio) is approximately 1). It is preferable because unevenness of illuminance of light emitted from the emission surface can be further reduced. On the other hand, when the planar shape of the light guide plate 2 is a rectangle, the configuration in which the semiconductor laser element 101 is disposed so as to face the side end surface of the light guide plate 2 that forms the short side of the rectangle reduces the unevenness of light illuminance. It is suitable because it can be further reduced.

  Further, compared with the first embodiment, the end surface 2c which is the light receiving end surface is formed at the corner of the light guide plate 2, and the semiconductor laser element 101 is disposed closer to the light guide plate 2, so that the surface light emitting device. The bezel (surrounding frame (frame portion)) can be made smaller and the frame can be reduced. Therefore, the ratio of the area of the surface 2a of the light guide plate 2 that is the emission surface to the surface area of the surface light emitting device can be further increased. Further, the surface light emitting device can be reduced in size. Therefore, the surface emitting device in which the semiconductor laser element 101 is arranged at the corner of the light guide plate 2 can be suitably used for a backlight of a liquid crystal display of a portable device.

(Embodiment 5)
FIG. 12 is a schematic diagram illustrating a configuration of the surface light emitting device according to the fifth embodiment. The fifth embodiment is different from the fourth embodiment described above in that the phosphor layer 3 is arranged as shown in FIG. Specifically, as shown in FIG. 12, the phosphor layer 3 is disposed on the end surface 2d side which is the end surface of the light guide plate 2 on the opposite side to the end surface 2c which is the light receiving end surface. That is, in the rectangular plate-shaped light guide plate 2, the phosphor layer 3 is provided on the end surface 2d, which is the side end surface of the light guide plate 2 excluding the two side end surfaces that form the corners where the semiconductor laser elements 101 are disposed. It has been.

  In contrast to the configuration in which the phosphor layer 3 is provided on the surface 2a side in the fourth embodiment, the phosphor layer 3 is provided on the end surface 2d side having a small surface area, so that the necessary amount of phosphor can be reduced. . Further, as described in the third embodiment, regarding the point where the monochromatic light of the laser beam is emitted from the surface 2a, the surface layer 2a is provided with a filter that cuts the wavelength of the laser beam on the surface 2a side. It is possible to cope with the combination of the end face 2d and the like.

  In the fourth and fifth embodiments, the example in which the semiconductor laser element 101 disposed at the corner of the light guide plate 2 is disposed so as to face the end surface 2c that is the light receiving end surface has been described. It is not necessary for all the laser light emitted from the semiconductor laser element 101 to be incident from the end face 2 c formed at the corner of the light guide plate 2. That is, the laser light can be incident on the light guide plate 2 not only from the end surface 2c but also from two side end surfaces of the light guide plate 2 sandwiching the end surface 2c.

  Further, the semiconductor laser element 101 may be disposed so as to be embedded in the corner. For example, a counterbore can be formed on the end face 2c of the corner, and the semiconductor laser chip 103, the submount 104, and the stem 105 can be fitted into the counterbore. By embedding the semiconductor laser element 101 in the corner, the bezel of the surface light emitting device can be further reduced, so that further downsizing of the surface light emitting device can be achieved.

(Embodiment 6)
FIG. 13 is a schematic diagram illustrating a configuration of the surface light emitting device according to the sixth embodiment. 14 is a side view of the surface light emitting device shown in FIG. The sixth embodiment is different from the first embodiment described above in that an optical film 8 is provided in addition to the phosphor layer 3. Specifically, as shown in FIGS. 13 and 14, the phosphor layer 3 is provided on the end face 2 c side of the light guide plate 2, and the optical film 8 is formed further on the light source side of the phosphor layer 3. Yes. The optical film 8 has a characteristic capable of transmitting laser light and reflecting light having a wavelength different from the wavelength of the laser light.

In the present embodiment, it is assumed that the semiconductor laser element 101 that is a light source oscillates at a wavelength of 405 nm. The phosphor layer 3 has two types of phosphor materials that receive light of a wavelength of 405 nm and emit red and blue-green light (red is CaAlSiN ₃ : Eu ²⁺ , and blue-green is Ca-α-SiAlON: Ce ^{3+, respectively).} )It is included. The optical film 8 is formed by laminating an AlN thin film and an Al ₂ O ₃ thin film in order from the semiconductor laser element 101 side so as to transmit laser light having a wavelength of 405 nm and reflect light having a wavelength different from that of the laser light. Yes.

  The optical film 8 preferably has a characteristic of transmitting only the vicinity of the wavelength of 405 nm, which is the wavelength of the laser light. However, any optical film having a characteristic of transmitting a wavelength in the vicinity of 405 nm (for example, 390 nm to 420 nm, which is a range of ± 15 nm with respect to the wavelength of the laser beam) is included in the optical film 8 of the present embodiment. Shall.

  Thus, by forming the optical film 8 on the light source side surface of the phosphor layer 3, the wavelength of the laser light can be selectively transmitted, so that the light generated in the phosphor layer 3 is transmitted by the light source. It is possible to prevent the laser beam from being emitted to a certain semiconductor laser element side. Therefore, it is possible to realize a surface light emitting device with improved light extraction efficiency.

(Embodiment 7)
FIG. 15 is a schematic diagram illustrating a configuration of the surface light emitting device according to the seventh embodiment. The seventh embodiment is different from the above-described third embodiment in that an end surface light reflecting portion 9 is provided on the side end surface of the light guide plate 2. Specifically, as shown in FIG. 15, a phosphor layer 3 is provided on an end surface 2d that is a side end surface of the light guide plate 2 that is not the light receiving end surface on the side opposite to the end surface 2c that is a light receiving end surface. An end face light reflecting portion 9 that reflects light is provided on the surface side of the layer 3 that does not face the light guide plate 2. Further, the end surface light reflecting portion 9 is also provided on the end surface 2 e side which is the other side end surface of the light guide plate 2. The end face light reflecting portion 9 can be formed by vapor-depositing Ag or Al, which is a metal having high reflectivity, for example.

  The emission surface from which light is emitted from the light guide plate 2 is the surface 2a. That is, the end surface 2d opposite to the light receiving end surface is not an emission surface. In this case, by providing the end surface light reflecting portion 9 on the end surface 2d, the light that has totally reflected the inside of the light guide plate 2 and reached the end surface 2d is reflected by the end surface light reflecting portion 9, so that light is transmitted from the end surface 2d to the outside. Can be prevented. Since the end surface light reflecting portion 9 is further provided on the outer surface of the end surface 2d where the phosphor layer 3 is provided, light of any color such as white light is emitted from the phosphor layer 3, for example. Can be emitted from the surface 2a. Further, the end surface 2e is also provided with an end surface light reflecting portion 9, and the reflection sheet 4 is disposed on the back surface 2b opposite to the front surface 2a (see FIG. 3), so that light is transmitted from the end surface 2e and the back surface 2b to the outside. Can also be prevented from exiting. Accordingly, it is possible to realize a surface light-emitting device that can emit light only from a predetermined emission surface and further improve the light use efficiency. FIG. 15 shows a configuration in which the end surface light reflecting portions 9 are provided on the entire end surfaces 2 d and 2 e, but the end surface light reflecting portions 9 are provided on at least a part of the side end surfaces other than the light receiving end surfaces of the light guide plate 2. If it is a structure, the effect which can reflect light by the end surface light reflection part 9 and can improve the utilization efficiency of light can be acquired similarly.

  In the first to seventh embodiments, the surface emitting device that emits light from the surface 2a of the light guide plate 2 has been described. Since light is emitted from the surface 2a, which is a wide surface that is not an end surface, such a surface light-emitting device can be particularly advantageously applied to an edge light type backlight for portable devices. However, the surface light emitting device of the present invention is not limited to the configuration in which the surface 2a is the exit surface. For example, one or more of the side end surfaces of the light guide plate 2 may be used as the exit surface. Moreover, it is good also as a surface light-emitting device which light radiate | emits from both the surface of a light-guide plate, and a side end surface.

(Embodiment 8)
In the embodiments so far, the example of the surface light emitting device suitably used as the backlight has been described. However, in the following, an example in which the surface light emitting device is used as indoor lighting will be described. FIG. 16 is a schematic diagram illustrating a configuration of the surface light emitting device according to the eighth embodiment, and is a schematic diagram illustrating an example in which the surface light emitting device is used as room illumination. As shown in FIG. 16, in the surface light-emitting device 11, the two light guide plates 2 are combined in a V shape. The semiconductor laser element 101 which is a light source of the surface light emitting device 11 is disposed so as to face the end surface 2c of the light guide plate 2 having a rectangular plate shape. The semiconductor laser element 101 is placed on a suitable support (not shown). A phosphor layer 3 is provided on the end face 2 c side of the light guide plate 2.

  The sticking member 12 is disposed so as to be bridged in a V shape formed by the two light guide plates 2, and the light guide plate 2 and the sticking member 12 form a hollow triangular prism shape. On the bonding surface 12a of the bonding member 12, the surface light emitting device 11 is bonded and fixed to the ceiling or wall surface. A power supply unit 14 for driving the semiconductor laser element 101 is disposed in a space 13 formed inside the light guide plate 2 and the sticking member 12. The semiconductor laser element 101 and the power supply unit 14 are connected by a metal wire 15.

  Laser light oscillated from the semiconductor laser element 101 has radiation characteristics that spread in a band shape. In the end face 2c, the semiconductor laser is such that the longitudinal direction of the belt-like spread is along the long side direction of the rectangular shape of the end face 2c, and the short side direction of the belt-like spread is along the short side direction of the rectangular shape of the end face 2c. Element 101 is arranged.

  A reflection sheet (not shown) is affixed to the surface opposite to the surface 2a of the light guide plate. Moreover, although not shown in figure, the diffusion sheet is affixed on the surface 2a and the end surface 2e of a light-guide plate. The laser light incident on the light guide plate 2 is reflected to the surface 2a side by the reflection sheet, and is emitted to the outside from the surface 2a and the end surface 2e as indicated by an arrow VL. That is, the emission surfaces from which light is emitted from the light guide plate 2 are the surface 2a and the end surface 2e. Since the laser light enters the light guide plate 2 through the phosphor layer 3, the color of the light emitted from the light guide plate 2 can be arbitrarily adjusted by including an appropriate phosphor in the phosphor layer 3.

  Thus, the surface light-emitting device 11 can be applied particularly advantageously as indoor lighting that is used while being fixed to the ceiling or wall surface of the room. In the surface emitting device 11, almost all of the laser light emitted from the semiconductor laser element 101 can be incident on the light guide plate 2, so that the light use efficiency can be improved. Therefore, the surface light-emitting device 11 formed by combining two rectangular light guide plates 2 emits a wide area by efficiently emitting light from the emission surface because the light use efficiency is high. Can do.

(Embodiment 9)
FIG. 17 is a schematic diagram illustrating a configuration of the surface light emitting device according to the ninth embodiment, and is a schematic diagram illustrating another example in which the surface light emitting device is used as room lighting. As shown in FIG. 17, the light guide plate 2 of the ninth embodiment is not in the shape of a rectangular plate. The light guide plate 2 is formed in a bowl shape in which one long side of a rectangle is raised in a bow shape in a cross-sectional shape along the end face 2c which is a light receiving end face.

  Laser light having a band-like radiation characteristic oscillated from the semiconductor laser element 101 is incident on the end face 2 c of the light guide plate 2. The reflective sheet 4 is affixed to the surface of the saddle-shaped light guide plate 2 on the side opposite to the surface 2a, which is a curved surface that rises in a bow shape. The light reflected on the surface 2a side by the reflection sheet 4 is emitted from the surface 2a to the outside. That is, the surface 2a is an exit surface. The phosphor layer 3 is provided on the surface 2 a side of the light guide plate 2. Since the light emitted to the outside passes through the phosphor layer 3, the light emitted from the phosphor layer 3 can be efficiently emitted to the outside, and the light utilization efficiency can be improved. In the surface light emitting device according to the ninth embodiment, since the surface 2a that is a bowl-shaped curved surface is an emission surface, light can be irradiated over a wide range with one semiconductor laser element 101.

  As described above, the shape of the light guide plate 2 is not limited to the rectangular plate shape. If the shape of the laser beam emitted from the semiconductor laser element 101 spreads in a band shape is substantially plate-shaped so that the longitudinal direction of the cross-sectional shape along the light receiving end surface of the light guide plate 2 can be aligned, the light guide plate 2 may have any shape. For example, the light guide plate 2 may have a wedge shape, a cross-sectional wedge-shaped flat plate, or a plate shape having a triangular plane shape.

(Embodiment 10)
FIG. 18 is a schematic diagram illustrating a configuration of the surface light emitting device according to the tenth embodiment, and is a schematic diagram illustrating still another example in which the surface light emitting device is used as room lighting. The surface light-emitting device of Embodiment 10 and the surface light-emitting device of Embodiment 9 described above basically have the same configuration. However, in the tenth embodiment, as shown in FIG. 18, the phosphor layer 3 is not provided on the surface 2 a of the light guide plate 2 that is the emission surface, and the reflection plate 16 is provided instead of the reflection sheet 4. This is different from the ninth embodiment.

  In the tenth embodiment, the phosphor that absorbs the laser light emitted from the semiconductor laser element 101 and emits light having a wavelength different from the wavelength of the laser light reflects the light and guides it to the emission surface side. It is included in the reflector 16. Specifically, dots (projections) containing phosphors are formed on the surface of the reflecting plate 16 facing the light guide plate 2. The dots are sparse on the side close to the semiconductor laser device 101 (that is, the interval between adjacent dots is larger) and become denser (that is, the interval between adjacent dots is smaller) as the distance from the light source increases. Is formed. By adopting such a configuration, when a laser beam hits the dot, a part of the light emitted from the phosphor is not totally reflected and is emitted from the light emitting surface to the outside of the light guide plate 2. .

  In the configuration in which the phosphor layer 3 is provided on the emission surface shown in the ninth embodiment, when the emission surface is wiped and cleaned, for example, when dust is accumulated on the emission surface, the phosphor is partially peeled off. Doing so may damage the phosphor layer. If the phosphor is scratched, uneven illuminance of light occurs and uniform light cannot be emitted. Therefore, it is required to perform maintenance (cleaning) of the surface light emitting device so as not to damage the phosphor. On the other hand, according to the configuration in which the reflecting plate 16 of the tenth embodiment includes the phosphor, since the phosphor is not provided on the exit surface, the phosphor layer is damaged when the exit surface is cleaned. This can be prevented, and maintenance (cleaning) of the surface light emitting device is facilitated.

  Further, in order to emit uniform light from the exit surface of the light guide plate 2, there is a distance between the phosphor and the diffusion member that diffuses the light in order to sufficiently mix the light emitted from the phosphor. It is considered necessary. In the configuration in which the phosphor layer 3 is provided on the surface 2a that is the emission surface, it is necessary to dispose the diffusion sheet so as to form a gap between the phosphor layer 3 and the diffusion sheet, and the thickness of the surface light emitting device is large. Become. On the other hand, in the configuration in which the reflecting plate 16 includes the phosphor, the light guide plate 2 is disposed between the phosphor and the diffusing member, so that the phosphor and the diffusing member can be separated without forming a gap. Since the distance between them can be ensured, the surface light emitting device can be downsized.

  In the above description, an example in which the laser light oscillated by the semiconductor laser element 101 is directly incident on the light guide plate 2 (or only through the phosphor layer 3) has been described. An optical member may be arranged in the laser light path between the light guide plate 2 and the radiation characteristic of the laser light incident on the light guide plate 2 may be further optimized. Examples of the optical member include a cylindrical lens and a combination of a concave lens and a convex lens. For example, even when the light receiving end face has a large area and depending on the radiation characteristics of the laser light emitted from the semiconductor laser element, only a part of the light receiving end face can be irradiated with the laser light, the optical member as described above. Since the laser light can be irradiated to a wider range of the light receiving end face by one light source, it is possible to provide a surface light emitting device in which the illuminance unevenness of the light emitted from the surface light emitting device is small.

  Although the embodiments of the present invention have been described above, the configurations of the embodiments may be appropriately combined. In addition, it should be considered that the embodiment disclosed this time is illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is an exploded perspective view of a surface light emitting device according to a first embodiment. It is sectional drawing which follows the II-II line | wire shown in FIG. 1 in the state which assembled the surface emitting device. It is a schematic diagram which shows arrangement | positioning of the light-guide plate with respect to a laser beam. It is another schematic diagram which shows arrangement | positioning of the light-guide plate with respect to a laser beam. It is a schematic diagram which shows the semiconductor laser element seen from the end surface side on the opposite side to the light-receiving end surface of a light-guide plate. It is a schematic diagram which shows the chip | tip part of a semiconductor laser element. It is a perspective view of one stripe part which comprises a semiconductor laser element. It is a schematic diagram which shows the radiation characteristic of the light radiate | emitted from a semiconductor laser element. It is a schematic diagram which shows the structure of the surface emitting device of Embodiment 2. FIG. 6 is a schematic diagram illustrating a configuration of a surface light emitting device according to a third embodiment. It is a schematic diagram which shows the structure of the surface emitting device of Embodiment 4. FIG. 10 is a schematic diagram illustrating a configuration of a surface light emitting device according to a fifth embodiment. It is a schematic diagram which shows the structure of the surface emitting device of Embodiment 6. It is a side view of the surface emitting device shown in FIG. FIG. 10 is a schematic diagram illustrating a configuration of a surface light emitting device according to a seventh embodiment. FIG. 10 is a schematic diagram illustrating a configuration of a surface light emitting device according to an eighth embodiment. It is a schematic diagram which shows the structure of the surface emitting device of Embodiment 9. It is a schematic diagram which shows the structure of the surface emitting device of Embodiment 10.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Surface light-emitting device, 2 Light-guide plate, 2a surface, 2b back surface, 2c, 2d, 2e End surface, 3 Phosphor layer, 4 Reflective sheet, 5 Diffusing sheet, 6 Case, 7 Cover, 7a Opening part, 8 Optical film, 9 End face light reflection part, 11 surface light emitting device, 12 sticking member, 12a sticking face, 13 space, 14 power supply part, 15 metal wire, 16 reflector, 101 semiconductor laser element, 103 semiconductor laser chip, 104 submount, 105 Stem, 106 metal wire, 108 terminal, 110 substrate, 111 buffer layer, 112 lower cladding layer, 113 active layer, 114 upper cladding layer, 115 contact layer, 116 side electrode, 117 side electrode, 118 insulating film, 119 electrode, 120 Pad electrode, 121 fused metal film layer, 122 groove, 130 laser light, 131 light emission Part, VL arrow, W width.

Claims (10)

An edge-emitting semiconductor laser device having a laminated structure including a light emitting layer;
A light guide member disposed with a light receiving end face facing the light emitting surface of the semiconductor laser element,
A cross section in a direction along the light receiving end surface of the light guide member has a longitudinal direction,
The surface emitting device, wherein the semiconductor laser element is arranged so that a stacking direction of the stacked structure is along the longitudinal direction. The light emitting layer has a light emitting portion from which laser light is emitted on the light emitting surface,
2. The surface light emitting device according to claim 1, wherein a ratio value obtained by dividing the dimension of the light emitting unit in the width direction orthogonal to the stacking direction by the dimension of the light emitting unit in the stacking direction is 50 or more.   The light reflection member which reflects light and guides it to the said output surface side is provided in the opposite side to the output surface of the said light guide member in which light radiate | emits from the said light guide member. The surface light-emitting device as described.   4. The phosphor according to claim 3, wherein the light reflecting member includes a phosphor that absorbs laser light emitted from the semiconductor laser element and emits light having a wavelength different from the wavelength of the laser light. Surface emitting device.   Light having a wavelength different from the wavelength of the laser light is absorbed by at least one of the light receiving end surface and the end surface of the light guide member opposite to the light receiving end surface by absorbing the laser light emitted by the semiconductor laser element. The surface emitting device according to any one of claims 1 to 3, wherein a phosphor layer that emits light is provided. The light receiving end face is provided at a corner of the light guide member,
A phosphor layer that absorbs laser light emitted from the semiconductor laser element and emits light having a wavelength different from the wavelength of the laser light on the end face of the light guide member excluding the end face that forms the corner. The surface emitting device according to claim 1, which is provided.   The surface light-emitting device according to claim 5, wherein the light guide member is made of a transparent material.   A phosphor layer that absorbs laser light emitted by the semiconductor laser element and emits light having a wavelength different from the wavelength of the laser light on an emission surface of the light guide member from which light is emitted from the light guide member The surface emitting device according to claim 1, wherein the surface light emitting device is provided.   9. The surface light-emitting device according to claim 4, wherein an optical film is formed on the light-receiving end face so as to transmit the laser light and reflect light having a wavelength different from that of the laser light.   The surface light-emitting device in any one of Claims 1-9 in which the end surface light reflection part which reflects light is provided in at least one part of the end surfaces of the said light guide members other than the said light-receiving end surface.

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