JP2012243529A - Linear light source device and planar light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear light source device and a planar light source device wherein heat radiation is improved.SOLUTION: The linear light source device includes a light-emitting device, a light guide, a circuit board, and a metal plate. The light-emitting device has a first plate electrode, a second plate electrode, a semiconductor light-emitting element, and an insulator arranged by coming in contact with the first plate electrode and the second plate electrode. The light-emitting device includes a light-emitting device capable of emitting a light beam from the semiconductor light-emitting element arranged on a range sandwiched between the first plate electrode and the second plate electrode. The light guide is a light guide capable of guiding the introduced light beam, and has an emitting surface extended along a light-guiding direction. The circuit board has a conductive section capable of feeding power to the second plate electrode of the light-emitting device. The metal plate feeds power to the first plate electrode of the light-emitting device arranged on the circuit board. The light beam is emitted from the emitting surface of the light guide.

Description

  Embodiments described herein relate generally to a linear light source device and a planar light source device.

  As a semiconductor light emitting element used in such a light source device, one that emits light in a wavelength range of ultraviolet light to visible light can be used.

  If a large number of surface light emitting elements are arranged, a linear light source device can be obtained. However, the temperature rise of the light emitting element due to the increase in power consumption increases. In addition, the spread of light is large. For this reason, it is difficult to increase the luminous efficiency.

  If a light beam having a small divergence angle is used and the light beam can be guided using an elongated light guide, an efficient linear light source device can be obtained. However, when a light emitting device in which a light emitting element is mounted on a CAN type package is used, it is difficult to obtain side light emission and heat dissipation is insufficient.

JP 2005-316337 A

  A linear light source device and a planar light source device with improved heat dissipation are provided.

  The linear light source device according to the embodiment includes a light emitting device, a light guide, a circuit board, and a metal plate. The light emitting device includes a first plate electrode, a second plate electrode, a semiconductor light emitting element, and an insulator provided in contact with the first plate electrode and the second plate electrode. The light emitting device includes a light emitting device capable of emitting a light beam from the semiconductor light emitting element provided in a region sandwiched between the first plate electrode and the second plate electrode. The light guide is a light guide capable of guiding the introduced light beam and has an emission surface extending along the light guide direction. The circuit board has a conductive portion capable of supplying power to the second plate electrode of the light emitting device. The metal plate has a part of a circuit that presses and supplies power to the first plate electrode of the light emitting device disposed on the circuit board, and has a heat radiation function, and extends in the light guide direction. The light beam is emitted from the emission surface of the light guide.

  The planar light source device according to the embodiment includes the above-described linear light source device, a light guide plate, a reflection sheet, and an optical sheet. The light guide is provided to face the emission surface, has a side surface on which the emitted light can enter, and can guide the emitted light in a planar shape. The reflection sheet is provided on one surface of the light guide plate, and can reflect the emitted light guided in the planar shape upward. The optical sheet is provided on the other surface of the light guide plate on the side opposite to the reflection sheet, and is capable of diffusing and transmitting the emitted light and the light reflected by the reflection sheet.

  A linear light source device and a planar light source device with improved heat dissipation are provided.

FIG. 1A is a schematic perspective view of the linear light source device according to the first embodiment, FIG. 1B is a partially enlarged schematic perspective view, and FIG. 1C is a schematic cross-section along the line AA. FIG. 1 (d) is a schematic diagram showing a heat dissipation path. 2A is a schematic diagram in which four light emitting devices are connected in parallel, and FIG. 2B is a schematic diagram in which three light emitting devices are connected in series. It is a model perspective view of the light-emitting device used for the linear light source device of 1st Embodiment. 4A is a schematic perspective view of a linear light source device according to a first modification of the first embodiment, FIG. 4B is a schematic perspective view in which the portion is enlarged, and FIG. 4C is a second modification. FIG. 4D is a schematic perspective view of the linear light source device of FIG. 5A is a schematic cross-sectional view of a light emitting device in which a concave portion is provided on the second plate electrode, FIG. 5B is a schematic plan view thereof, and FIG. 5C is a light emission in which a convex portion is provided on the second plate electrode. FIG. 5D is a schematic cross-sectional view of the apparatus, and FIG. 6A is a schematic cross-sectional view in which the first plate electrode and the metal plate are connected by a conductive material, FIG. 6B is a schematic cross-sectional view in which the first plate electrode and the light emitting device are screwed, and FIG. 6C. FIG. 6 is a schematic cross-sectional view in which the first plate electrode is pressed by a spring, and FIG. 6D is a schematic cross-sectional view in which the first plate electrode and the metal plate are crimped. FIG. 7A is a schematic plan view of a linear light source device according to a comparative example, and FIG. 7B is a schematic front view thereof. FIG. 8A is a configuration diagram of a planar light source device using the linear light source device according to the first embodiment and its modification, and FIG. 8B is a schematic front view. Fig.9 (a) is a graph which shows the temperature change of the linear light source device in a planar light source device, FIG.9 (b) is a schematic diagram which shows a temperature measurement location.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a schematic perspective view of the linear light source device according to the first embodiment, FIG. 1B is a schematic perspective view in which the region EN is partially enlarged, and FIG. 1C is along the line AA. FIG. 1D is a schematic diagram showing a heat dissipation path.
The linear light source device includes a light emitting device 10, a light guide 30, a phosphor layer 50, a circuit board 40 for wiring, and a metal plate 32.

  The circuit board 40 is made of a base material having a high thermal conductivity such as aluminum or ceramic. When the base material is an insulating material such as ceramic, a conductive portion 46 that can supply power to the second plate electrode of the light emitting device 10 is provided on the upper surface 40 a of the circuit board 40. Moreover, you may have the electric power feeding connector 42 which connects the electroconductive part 46 and a power supply.

2A is a schematic diagram in which four light emitting devices are connected in parallel, and FIG. 2B is a schematic diagram in which three light emitting devices are connected in series.
In this figure, the first plate electrode 12 is an anode and the second plate electrode 14 is a cathode, but they may have opposite polarities. As shown in FIG. 2A, the metal plate 32 is part of a circuit that is in pressure contact with the first plate electrodes 12 of the four light emitting devices 10 and can supply power to the light emitting devices 10. It acts as a heat dissipation path for dissipating the generated heat from the first plate electrode 12 to the outside. Also, heat is dissipated to the outside from the second plate electrode 14 of the light emitting device 10 via the circuit board 40. For example, the metal plate 32 can have a thickness in the range of 0.5 to 2 mm and a width in the range of 4 to 10 mm.

  Further, as shown in FIG. 2B, the light emitting device 10a is disposed between the metal plate 32a and the conductive portion 46a, and the light emitting device 10b, the metal plate 32b and the conductive portion 46b are disposed between the conductive portion 46a and the metal plate 32b. A light emitting device 10c may be provided between each to provide a series connection. Furthermore, the heat radiation performance can be improved by bringing the metal plate 32 and the circuit board 40 directly or through an insulating sheet into contact with a casing or a heat radiation plate having a large heat radiation area.

  The light guide 30 is made of a transparent material such as glass or acrylic, and can guide the light beam emitted from the light emitting device 10. The light beam propagates inside the light guide 30 or is reflected at the interface with the outside, and then emitted as emitted light G from the exit surface 30a extending along the light guide direction.

  The wavelength converter made of the phosphor layer 50 or the like can be provided on a part of the surface of the light guide 30 or inside the light guide 30. When the light beam is blue light, a layer including a green phosphor that absorbs blue light and emits green light or a red phosphor that absorbs blue light and emits red light may be provided. Alternatively, a layer including a phosphor that absorbs blue light and emits yellow light may be provided. Furthermore, when the light beam has a wavelength of ultraviolet light to blue-violet light, layers each including phosphors that emit blue light, green light, and red light may be provided.

  These wavelength-converted light and the light beam that is not absorbed by the phosphor layer 50 are emitted from the emission surface 30 a of the light guide 30. In this way, white light can be obtained as mixed light.

  When the light guide 30 is formed in a rod shape, a linear light source can be obtained. The cross section of the light guide 30 may be a circle, an ellipse, a rectangle, a polygon, or the like. When the light guide 30 has a rectangular cross section, the light guide 30 may be housed in the light guide case 34 so that the emission surface 30a is exposed. Further, if the metal plate 32 is fixed to the light guide case 34 with screws or the like, the heat dissipation can be further improved. Furthermore, if the light guide case 34 made of metal is provided so as to be in contact with the phosphor layer 50, the converted light can be efficiently emitted from the emission surface 30a.

FIG. 3 is a schematic perspective view of a light emitting device used in the linear light source device according to the first embodiment.
The light emitting device 10 includes a first plate electrode 12 made of metal, a second plate electrode 14 made of metal, a semiconductor light emitting element 16, an insulation provided in contact with the first plate electrode 12 and the second plate electrode 14. And a body 18. The light beam 20 can be emitted in the lateral direction from the semiconductor light emitting device 16 provided in the region between the first plate electrode 12 and the second plate electrode 14. The insulator 18 has a window that can transmit the light beam 20. In the CAN package, the light beam 20 is emitted from the surface of the window. On the other hand, when the package of the present embodiment is used, the light beam 20 is emitted toward the side surface of the region sandwiched between the two plate electrodes. In FIG. 3, the planar shape of the package is a circle, but it may be a rectangle or a polygon.

  The first plate electrode 12 and the second plate electrode 14 can be made of, for example, copper, FeNi-based Kovar metal, jumet wire (copper-coated nickel steel wire), or the like. A submount (not shown) made of ceramic or silicon may be used between the semiconductor light emitting element 16 and the first plate electrode 12 or between the semiconductor light emitting element 16 and the second plate electrode 1414. In this case, the stress on the semiconductor light emitting element 16 can be reduced. The semiconductor light emitting element 16 and the plate electrode can be electrically connected using metal bumps (not shown) or bonding wires (not shown).

  If the light emitting element 16 is made of an InGaAlN-based material, it can be emitted light in the ultraviolet to green wavelength range. If the light-emitting element 16 is made of an InAlGaP-based material, emitted light in the wavelength range of green to red can be obtained. If the light emitting element 16 is made of an AlGaAs material, infrared light can be emitted. The light emitting element 16 may be an LD (Laser Diode), an LED (Light Emitting Diode) having a small light beam spread angle, or the like.

  In addition, when it is set as monochromatic linear light source devices, such as red, yellow, and green, a fluorescent substance layer does not need to be provided. Further, a phosphor layer may be provided inside or on the surface of the insulator 18 of the light emitting device 10 so that the light beam 20 is white light. In this case, it is not necessary to provide a phosphor layer in the vicinity of the light guide.

FIG. 4A is a schematic perspective view of a linear light source device according to a first modification of the first embodiment, FIG. 4B is a schematic perspective view in which it is partially enlarged, and FIG. 4C is a second modification. FIG. 4D is a schematic perspective view showing a partially enlarged view of an example of the linear light source device. In this figure, the metal plate and the light guide case are omitted.
The light guide 30 may be continuous. In this case, the light guide 30 can be provided with a notch 30b, and the light emitting device 10 can be inserted into the notch 30b. In this way, a phosphor layer or a reflective layer is provided in the vicinity of the light emitting device 10 to suppress the generation of a dark portion in the linear light source, and the linear light source device having a uniform emission intensity along the linear emission surface. It can be.

  4A and 4B, one light emitting device 10 is inserted into the notch 30b. In this case, for example, all the light beams 20 propagate in the same direction (BI). On the other hand, in FIGS. 4C and 4D, two light emitting devices are inserted adjacent to one notch 30b. In this case, the light beam 20 propagates in opposite directions (B1 and B2). Note that a light-emitting device 10 may be inserted by providing a through-hole penetrating the top and bottom of the light guide 30.

  4A and 4B, the light emitting device 10 is disposed in the region where the light beam 20 of the light guide 30 propagates. However, the light emitting device 10 is disposed at both ends of the light guide 30, respectively. The light beam 20 may be emitted from both ends of the light guide 30 inward.

5A is a schematic cross-sectional view of a light emitting device in which a concave portion is provided on the second plate electrode, FIG. 5B is a schematic plan view thereof, and FIG. 5C is a light emission in which a convex portion is provided on the second plate electrode. FIG. 5D is a schematic cross-sectional view of the apparatus, and FIG.
5A and 5B, the second plate electrode is provided with a recess 14a, and the circuit board 40 is provided with a conductive portion 46a having a shape corresponding to this shape. If it does in this way, positioning of light-emitting device 10 will become easy.

  5C and 5D, the second plate electrode 14 of the light emitting device 10 is provided with a convex portion 14b, and the circuit board 40 is provided with a positioning hole 40a having a shape corresponding to the convex portion 14b. When the convex portion 14b and the positioning hole 40a are fitted, the positioning of the light emitting device is facilitated.

  6A is a schematic cross-sectional view in which the first plate electrode 12 and the metal plate 32 are connected by a conductive material, and FIG. 6B is a schematic cross-sectional view in which the first plate electrode 12 and the light emitting device 10 are fixed with screws 33. 6C is a schematic cross-sectional view in which the first plate electrode 12 is pressed by a spring 37, and FIG. 6D is a schematic cross-sectional view in which the first plate electrode 12 and the metal plate 32 are crimped. The conductive material 47 in FIG. 6A can be, for example, a solder material, a metal bump, a conductive rubber, or the like. Even if these connection methods are used, the metal plate 32 and the first plate electrode 12 are securely connected, and power feeding and heat dissipation are facilitated.

FIG. 7A is a schematic plan view of a linear light source device according to a comparative example, and FIG. 7B is a schematic front view thereof.
The light guide 130 is housed in the light guide case 134. The phosphor layer 150 is provided between the lower surface 130c of the light guide 130 and the bottom surface of the light guide case 134, for example. The light guide case 134 is disposed on the circuit board 140.

  The light emitting devices 110 and 111 are CAN type LDs. Part of each of the light beams 120 and 121 emitted from the glass window on the upper surface of the CAN is incident from the side surfaces 130d and 130e of the light guide 130 and propagates inside the light guide 130. The converted light by the phosphor layer 140 and the light beam component that has not been absorbed by the phosphor layer 140 are emitted from the emission surface 130a of the light guide 130 as emitted light GG.

  The CAN type light emitting devices 110 and 111 are disposed on the LD circuit boards 150 and 151, and the anode lead and the cathode lead are insulated from each other. The LD circuit boards 150 and 151 are disposed on the circuit board 140 having the conductive portions 146, 147, 148, and 149. The lead 110a and the conductive part 146 are connected to the lead 110b and the conductive part 148, respectively. Further, the lead 111a and the conductive portion 147 are connected, and the lead 111b and the conductive portion 149 are connected. The lead diameter is as thin as 0.45 mm, for example, and is insufficient as a heat dissipation path for heat generated in the light emitting devices 110 and 111. Even if an SMD (Surface Mounted Device) type package is used, the lead thickness is, for example, 0.1 to 0.3 mm, which is insufficient as a heat dissipation path.

  For this reason, when operating at a high current, the operating temperature of the light emitting element rises, and the light emission efficiency and long-term reliability decrease. Further, it is difficult to provide a light guide in a region where the light emitting devices 110 and 111 having a large shape are provided, and it is difficult to obtain a linear light source device with high uniformity. Furthermore, there are mounting problems such as the assembly process becoming complicated.

  On the other hand, in 1st Embodiment and the modification accompanying this, electric power feeding and heat dissipation can be made easy because the metal plate 32 press-contacts the plate electrode of the light-emitting device 10. FIG. Note that the circuit board can be used as a highly heat-conductive material such as metal or ceramic. For this reason, even if the light emitting device is driven with a high current, the temperature rise can be reduced, and the decrease in light emission efficiency and reliability can be suppressed.

  As a result, a high output can be obtained with a small number of light emitting devices, and the price of the linear light source device can be easily reduced. In addition, it is easy to obtain a linear light source with high emission intensity uniformity along the emission surface 30a of the light guide 30. For this reason, it can be used as, for example, a linear light source for a printer.

FIG. 8A is a configuration diagram of a planar light source device using the linear light source device according to the first embodiment and its modification, and FIG. 8B is a schematic front view.
The planar light source device includes a linear light source device 60, a back frame 70, a reflection sheet 72, a light guide plate 74, an optical sheet 76, and a front sheet 78.

  The back surface 40 b of the circuit board 40 of the linear light source device 60 is provided in close contact with the upper surface of the back frame 70. A reflection sheet 72 is provided in the upper surface area of the back frame 70 where the circuit board 40 is not provided. The exit surface 30a of the light guide 30 is opposed to one side surface of the light guide plate 74, and is provided on the reflection sheet 72 so that the exit light G can be introduced. Further, an optical sheet 76 and a front sheet 78 are provided on the light guide plate 74.

  When these are assembled, the planar light source device of FIG. For example, if the length of the linear light source device 60 is 35 cm and the six light emitting devices 10 are provided, a backlight light source of an image display device having a diagonal line size of 16 inches can be obtained.

Fig.9 (a) is a graph which shows the temperature change of the linear light source device in a planar light source device, FIG.9 (b) is a schematic diagram which shows a temperature measurement location.
In FIG. 9A, the vertical axis represents temperature (° C.) and the horizontal axis represents time (minutes). In addition, the light-emitting device 10 was six and power consumption was 14.7W. The circuit board 40 is made of Al having a high thermal conductivity. The ambient temperature AMB was constant at about 26 ° C.

  The temperature at the point B of the second plate electrode 14 of the light emitting device 10 increased with the time from the start of driving, and was about 53 ° C. after 90 minutes, which was 26.4 ° C. (ΔT2) higher than the ambient temperature. Further, the temperature at the point T on the upper surface of the metal plate 32 in pressure contact with the first plate electrode 12 of the light emitting device 10 became about 51 ° C. 90 minutes after the start of driving. Further, the temperature BF of the back frame 70 immediately below the light emitting device 10 was about 46 ° C. 90 minutes after the start of driving, which was 19.6 ° C. (ΔT1) higher than the ambient temperature.

  In the planar light source device of the present embodiment, generated heat is dissipated from the first plate electrode 12 through the metal plate 32, and the circuit board 40 and the back frame 70 in close contact with the circuit board 40 are provided from the second plate electrode 16. Dissipated via. Moreover, heat dissipation is further improved by using a metal plate 32 and the circuit board 40 with a high heat conductive material such as aluminum.

  In this way, even at high current driving, the temperatures at points B and T can be set to 60 ° C. or lower, and the characteristics and reliability of the semiconductor light emitting element can be sufficiently maintained.

  In a linear light source device using a surface-emitting LED having a large light spread angle, it is difficult to efficiently introduce light into the side surface of a light guide plate having a thickness of 5 mm or less. On the other hand, if the linear light source device 60 of this embodiment is used, the emitted light G can be efficiently introduced into the side surface of the light guide plate 74 of the planar light source device. As a result, it is easy to reduce the number of light emitting devices. As a result, the price of the planar light source device can be reduced.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 Light-emitting device, 12 1st plate electrode, 14 2nd plate electrode, 16 Semiconductor light emitting element, 20 Light beam, 30 Light guide, 32 Metal plate, 40 Circuit board, 46 Conductive part, 50 Phosphor layer, 60 Linear Light source device, 72 reflection sheet, 74 light guide plate, 76 optical sheet, G outgoing light (from light guide)

Claims (8)

A light emitting device comprising: a first plate electrode; a second plate electrode; a semiconductor light emitting element; and an insulator provided in contact with the first plate electrode and the second plate electrode, wherein A light emitting device capable of emitting a light beam from the semiconductor light emitting element provided in a region sandwiched between a plate electrode and the second plate electrode;
A light guide capable of guiding the introduced light beam, the light guide having an exit surface extending along a light guide direction; and
A circuit board having a conductive portion capable of feeding power to the second plate electrode of the light emitting device;
A metal plate that feeds power to the first plate electrode of the light emitting device disposed on the circuit board;
With
The linear light source device, wherein the light beam is emitted from the emission surface of the light guide.   The linear light source device according to claim 1, wherein at least two of the light emitting devices are disposed between the circuit board and the metal plate. A phosphor layer provided on a part of or inside the surface of the light guide and capable of absorbing a part of the guided light beam and emitting converted light having a wavelength longer than the wavelength of the light beam; Prepared,
The linear light source device according to claim 1, wherein the converted light is emitted from the emission surface of the light guide and is mixed with the light beam. The light guide has a through hole or a notch,
The linear light source device according to claim 1, wherein the light emitting device is inserted into the through hole or the notch.   The linear light source device according to claim 2, wherein the propagation directions of the light beams are all the same.   The linear light source device according to claim 2, wherein the light beams of two light emitting devices provided adjacent to each other propagate in opposite directions. The linear light source device according to claim 1,
A planar light guide plate that is provided opposite to the exit surface, has a side surface on which the exit light from the exit surface can enter, and can guide the exit light;
A reflection sheet provided on one surface of the light guide plate and capable of reflecting the guided emitted light upward;
An optical sheet that is provided on the other surface of the light guide plate on the side opposite to the reflective sheet, and is capable of transmitting upward while diffusing the emitted light and the light reflected by the reflective sheet;
A planar light source device comprising:   The planar light source device according to claim 7, further comprising a back frame whose upper surface is in close contact with the rear surface of the circuit board.

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