JP2006319103A - Cooler for light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cool a light emitting diode chip efficiently, to stabilize the optical output of the light emitting diode chip, and further, to prevent the lowering of its light emitting efficiency. <P>SOLUTION: A cooler for light emitting diodes has a package 11 wherein the flow passage of a cooling liquid is formed in the periphery of the light emitting diode chip 17, a circulating-flow passage connected with the package for subjecting the cooling liquid 19 to a circulating flow into the external of the package 11, a pump 21 for making the cooling liquid flow through the circulating-flow passage, and a heat exchanger 22 for cooling the cooling liquid 19 flowing through the circulating-flow passage. Therefore, the light emitting diode chip 17 brought into a high temperature by subjecting it to a current application is cooled by the cooling liquid 19, the cooling liquid 19 having an increased temperature is so subjected by the pump 21 to the circulating flow through the circulating-flow passage, and further, the cooling liquid is so cooled by the heat exchanger 22 as to be able to cool the light emitting diode chip 17 efficiently. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling device for a light emitting diode.

  In a light emitting diode (LED) used as a light source for a conventional lighting device or the like, the amount of heat generation increases with high-density mounting. If the LED becomes high temperature due to heat generation, the LED itself, the electrode, and the like may be destroyed. Therefore, an efficient heat dissipation means is necessary to prevent this.

As a means for efficiently dissipating the heat generated by the LED, there is one using a heat sink (heat dissipating plate) (for example, see Patent Document 1). For example, as shown in FIG. 6, a heat radiating plate 43 is adhered to the back surface of a package 41 containing a substrate 46 on which a light emitting diode chip 47 is formed. Heat generated in the light emitting diode chip is conducted to the heat radiating plate 43 through the substrate 46 and the package 41, and is released into the air by cooling the heat radiating plate 43 with air.
In addition, in order to forcibly cool the heat radiating plate, there are one in which an air cooling fan is provided integrally with the heat radiating plate and another in which a refrigerant is circulated in the heat radiating plate.
Japanese Patent Laid-Open No. 2003-104086

  However, in the above method, the heat generated in the light emitting diode chip is conducted to the heat radiating plate through the substrate and the package, so that the cooling efficiency is restricted by the thermal conductivity of the substrate and the package. If the cooling efficiency is poor, the light emitting diode chip becomes high temperature, and there is a problem that the light output becomes unstable or the light emission efficiency is lowered.

  An object of the present invention is to stabilize the light output of a light emitting diode chip and prevent a decrease in light emission efficiency by efficiently cooling the light emitting diode chip.

  In order to solve the above-described problems, the invention described in claim 1 is a light-emitting diode cooling device as shown in FIG. 1, for example, in which a light-emitting diode chip (17) is housed, and the light emission A package (11) in which a flow path of a cooling liquid (19) is formed around the diode chip, an annular flow path connected to the package for circulating the cooling liquid out of the package, and the cooling along the circular flow path A pump (micropump 21) for flowing the liquid and a heat exchanger (22) for cooling the cooling liquid flowing in the annular flow path are provided.

  According to the first aspect of the present invention, a package in which a cooling liquid flow path is formed around the light emitting diode chip, a circular flow path connected to the package for circulating the cooling liquid outside the package, and the cooling liquid in the circular flow path. And a heat exchanger that cools the coolant flowing in the annular flow path, so that the LED chip that becomes hot when energized is cooled by the coolant, and the coolant that has risen in temperature is removed. The light-emitting diode chip can be efficiently cooled by circulating in the annular flow path with a pump and cooling with a heat exchanger.

  According to a second aspect of the present invention, in the light-emitting diode cooling device according to the first aspect, as shown in FIG. 3, for example, the side of the package opposite to the surface from which light emitted from the light-emitting diode chip is emitted The annular flow path is connected to the surface.

  According to the second aspect of the present invention, since the annular flow path is connected to the surface opposite to the surface from which light emitted from the light emitting diode chip of the package is emitted to the outside, the light emitting surfaces of a plurality of packages are mounted side by side. In addition, the connection portion with the annular flow path is not obstructed, and a gap between adjacent packages can be eliminated to increase the LED mounting density.

  The invention according to claim 3 is a light-emitting diode cooling device, for example, as shown in FIG. 4, a package (11) in which a light-emitting diode chip (17) is housed, and one end connected to the package. And a heat pipe (31) in which a refrigerant is enclosed, and a heat exchanger (heat radiating plate 33) that is connected to the other end of the heat pipe and cools the refrigerant.

  According to the third aspect of the present invention, the heat generated in the light emitting diode chip in the package is absorbed by the refrigerant in the heat pipe having both ends connected to the package and the heat sink, and the heat absorbed by the refrigerant is heated. Since it is carried to the exchanger to dissipate heat, heat can be dissipated efficiently.

  According to a fourth aspect of the present invention, in the cooling device for a light emitting diode according to the third aspect, for example, as shown in FIG. 5, the flow path of the coolant (36) is provided around the light emitting diode chip in the package. It is formed.

  According to the fourth aspect of the present invention, since the flow path of the refrigerant in the heat pipe is formed around the light emitting diode chip in the package, the refrigerant directly contacts the light emitting diode chip. Can cool well.

  According to a fifth aspect of the present invention, in the light-emitting diode cooling device according to the third or fourth aspect, the heat pipe is connected to a surface of the package opposite to a surface from which light emitted from the light-emitting diode chip is emitted. It is characterized by that.

  According to the fifth aspect of the present invention, since the heat pipe is connected to the surface opposite to the surface from which light emitted from the light emitting diode chip of the package is emitted to the outside, the light emitting surfaces of a plurality of packages are mounted side by side. In addition, the connection portion with the heat pipe is not obstructed, and a gap between adjacent packages can be eliminated to increase the LED mounting density.

  According to the present invention, by efficiently cooling the light emitting diode chip, the light output of the light emitting diode chip can be stabilized and the light emission efficiency can be prevented from being lowered.

  Hereinafter, embodiments of the present invention will be described in detail. However, although various technically preferable limitations for implementing the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples.

<First Embodiment>
FIG. 1 is a schematic cross-sectional view showing the overall structure of a light-emitting diode cooling device according to a first embodiment of the present invention. The light emitting diode cooling device includes an LED 10 and a cooling unit 20.

  The LED 10 includes a package 11, a cover glass 15, a substrate 16, a light emitting diode chip 17, and power supply terminals 18a and 18b. The package 11 has an opening at the top, and the opening is closed by a cover glass 15. The surface of the cover glass 15 becomes the light emitting surface of the LED 10. That is, the light emission of the light emitting diode chip 17 is emitted from the opening closed by the cover glass 15.

  A substrate 16 and a light emitting diode chip 17 are accommodated in the internal space 12 of the package 11 closed by the cover glass 15, and a cooling liquid 19 is enclosed. As the cooling liquid 19, a liquid having a high light transmittance at a wavelength emitted from the light emitting diode chip 17, a high thermal conductivity, and a sufficiently low electric conductivity is preferable. As such a cooling liquid 19, for example, fluorine-based oil or silicon-based oil can be used.

  At the bottom of the package 11 facing the cover glass 15, power supply terminals 18 a and 18 b that penetrate the package 11 and protrude from the back surface of the package 11 are provided. Ends inside the package 11 of the power supply terminals 18 a and 18 b are connected to the light emitting diode chip 17 through the substrate 16. The power terminals 18a and 18b are connected to an external power source (not shown).

  On the side surface of the package 11, holes 13a and 13b for circulating the coolant 19 filled in the package 11 to the cooling unit 20 are provided. The holes 13a and 13b have liquid transport tubes 24a and 24b described later. Fittings 14a and 14b connected to are provided. The internal space 12 and the holes 13a and 13b serve as a flow path for circulating the coolant 19 to the external cooling unit 20.

The substrate 16 is fixed in the package 11 at a distance from the bottom of the package 11 by a spacer or the like (not shown). By leaving a space between the substrate 16 and the bottom of the package 11, the cooling liquid 19 also contacts the back surface of the substrate 16, and the substrate 16 can be efficiently cooled.
A light emitting diode chip 17 is provided on the front surface of the substrate 16, and power supply terminals 18 a and 18 b for supplying power to the light emitting diode chip 17 are connected to the back surface of the substrate 16. The light emitting diode chip 17 is disposed to face the cover glass, and light emitted from the light emitting diode chip 17 passes through the cover glass 15 and is emitted to the outside.

The cooling unit 20 includes a micro pump 21, a heat exchanger 22, a pipe 23 that connects the two, liquid transport tubes 24 a and 24 b, and a rotary fan 25.
The micropump 21 is connected to one joint 14a of the package 11 through a liquid transport tube 24a. The heat exchanger 22 is connected to the other joint 14b of the package 11 through the liquid transport tube 24b. The micropump 21 and the heat exchanger 22 are connected by a pipe 23, and an annular flow path for the coolant 19 is formed between the heat exchanger 22 and the package 11. The micropump 21 is a pump that circulates the coolant 19 between the heat exchanger 22 and the package 11, and determines the flow rate per unit time of the coolant 19 that flows through the annular flow path.

  The heat exchanger 22 includes a cooling pipe (not shown) through which the cooling liquid 19 flows. The cooling pipe forms an annular flow path for the cooling liquid 19 together with the liquid transport tubes 24 a and 24 b, the micropump 21, the pipe 23 and the package 11. A heat sink (not shown) is provided on the outer periphery of the cooling pipe, and the heat of the coolant 19 is conducted to the heat sink through the cooling pipe. The heat radiating plate is forced to cool by receiving wind generated by the rotary fan 25.

  Next, cooling of the LED 10 by the cooling unit 20 will be described. First, when the light emitting diode chip 17 is energized to emit light, heat is generated from the light emitting diode chip 17. Here, when the micropump 21 is driven, heat is conducted from the light emitting diode chip 17 and the substrate 16 to the coolant 19 flowing through the annular flow path, and the light emitting diode chip 17 and the substrate 16 are cooled. The coolant 19 whose temperature has risen is cooled in the heat exchanger 22.

  By using the cooling unit 20 as described above, the light emitting diode chip 17 can be efficiently cooled, the light output of the light emitting diode chip 17 can be stabilized, and the light emission efficiency can be prevented from being lowered.

  Note that a thermometer for measuring the temperature of the coolant 19 may be provided at an arbitrary location in the annular flow path, and the operation of the micro pump 21 may be adjusted according to the temperature of the coolant 19 to change the flow rate of the coolant 19.

  Further, the heat radiating plate may be naturally air-cooled without using the rotary fan 25. Further, the secondary cooling liquid 19 that cools the primary cooling liquid 19 flowing in the LED 10 package 11 may be provided with an annular flow path and a radiator plate in the heat exchanger 22, and the primary cooling liquid 19 may be cooled by the secondary cooling liquid 19. . Alternatively, natural air cooling, forced air cooling, or cooling by the secondary cooling liquid 19 may be selected or used in accordance with the heat generation amount of the light emitting diode chip 17 and the temperature of the cooling liquid 19.

<Modification 1>
FIG. 2 is a first modification of the LED 10 according to the first embodiment. In Modification 1, as shown in FIG. 2, the substrate 16 on which the light emitting diode chip 17 is provided is provided integrally with the bottom of the package 11. Thus, by providing the substrate 16 integrally with the bottom of the package 11, only the upper surface of the light emitting diode chip 17 may be cooled by the cooling liquid 19.

<Modification 2>
FIG. 3 is a second modification of the LED 10 according to the first embodiment. In Modification 2, as shown in FIG. 3, the substrate 16 provided with the light emitting diode chip 17 is provided integrally with the bottom of the package 11. Further, holes 13a and 13b for circulating the cooling liquid 19 filled in the package 11 to the cooling unit 20 are provided at the bottom of the package 11, and joints 14a and 14b connected to the liquid transport tubes 24a and 24b. Is protruded from the outer periphery of the holes 13a and 13b to the back surface of the package 11. For this reason, there is nothing in the side surface of the package 11 which protrudes.

  Thus, by providing the holes 13a and 13b and the joints 14a and 14b at the bottom of the package 11, when mounting a plurality of LEDs 10 side by side, a gap between the adjacent LEDs 10 can be eliminated, and the mounting density can be increased. it can.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
FIG. 4 is a schematic diagram showing the overall structure of the LED 10 and the cooling unit 20 according to the second embodiment of the present invention.
The cooling unit 20 of the present embodiment includes a heat pipe 31 and a heat radiating plate 33 of a heat exchanger (not shown). In the present embodiment, the substrate 16 having the light emitting diode chip 17 is provided integrally with the bottom of the package 11 of the LED 10. A heat pipe 31 for cooling the substrate 16 is integrally provided at the bottom of the package 11.

  One end of the heat pipe 31 is connected to the package 11 and is closed by the substrate 16. The refrigerant 32 in the heat pipe 31 is in contact with the back surface of the portion of the substrate 16 where the light emitting diode chip 17 is provided at one end connected to the package 11 of the heat pipe 31. The other end is connected to a heat radiating plate 33 inside the heat exchanger 22 (not shown). The heat pipe 31 is a sealed container made of a material having high thermal conductivity such as metal, and a small amount of refrigerant 32 is vacuum-sealed therein. Here, as the refrigerant 32, alternative chlorofluorocarbon, pure water, or the like can be used.

  The inner wall surface of the heat pipe 31 is provided with a network structure called a wick. Wick uses the capillary phenomenon to improve the recirculation speed of the refrigerant 32 to the heat source in the heat pipe 31.

  Here, the cooling operation of the LED 10 by the heat pipe 31 will be described. The liquid refrigerant 32 absorbs heat generated from the energized light emitting diode chip 17 through the substrate 16 at one end connected to the package 11 of the heat pipe 31 and evaporates. The vaporized refrigerant 32 moves in the heat pipe 31 and condenses at one end connected to the heat radiating plate 33 of the heat pipe 31.

At one end connected to the heat radiating plate 33 of the heat pipe 31, heat of condensation is generated when the gaseous refrigerant 32 condenses. The condensation heat is absorbed by the heat radiating plate 33 and released into the air. The liquefied refrigerant 32 moves in the heat pipe 31 along the wick and vaporizes again at one end connected to the package 11. By repeating this, heat radiation of the LED 10 can be performed efficiently.
Moreover, in this Embodiment, the motive power like the micro pump 21 of 1st Embodiment is unnecessary, and the energy required for cooling can be reduced.

  As shown in FIG. 5, a plurality of holes 34 a and 34 b penetrating the package 11 and the substrate 16 are provided, the holes 34 a and 34 b are connected to the heat pipe 31, and the interior space 12 of the package 11 and the inside of the heat pipe 31 are connected. Alternatively, the refrigerant 36 may be sealed. As such a coolant 36, a coolant having a high light transmittance at a wavelength emitted from the light emitting diode chip 17, a high thermal conductivity, and a sufficiently low electrical conductivity is preferable.

  When the package 11 having such a shape is used, the internal space 12 and the holes 34 a and 34 b serve as a flow path for the refrigerant 36 in the heat pipe 31, and the refrigerant 36 flowing through the flow path is in direct contact with the light emitting diode chip 17. Therefore, heat is directly conducted from the light emitting diode chip 17 to the refrigerant 36, and the cooling efficiency can be further increased.

  Although the light emitting diode has been described in the above embodiment, the present invention is not limited to this, and the present invention may be applied to a laser diode. In addition, it is needless to say that specific detailed structures can be changed as appropriate.

It is a schematic diagram which shows the cooling device of the light emitting diode which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the modification 1 of 1st Embodiment. It is a schematic diagram which shows the modification 2 of 1st Embodiment. It is a schematic diagram which shows the cooling device of the light emitting diode which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows the modification of 2nd Embodiment. It is a schematic diagram which shows the cooling device of the conventional light emitting diode.

Explanation of symbols

11 Package 17 Light-emitting diode chip 19 Coolant 21 Micro pump 22 Heat exchanger 31 Heat pipe 32, 36 Refrigerant 33 Heat sink

Claims (5)

A package in which a light emitting diode chip is housed and a flow path for a coolant is formed around the light emitting diode chip;
An annular flow path connected to the package for circulating the coolant out of the package;
A pump for causing the coolant to flow along the annular flow path;
A cooling device for a light emitting diode, comprising: a heat exchanger for cooling the coolant flowing in the annular flow path.   2. The light emitting diode cooling device according to claim 1, wherein the annular flow path is connected to a surface of the package opposite to a surface from which light emitted from the light emitting diode chip is emitted. A package containing a light emitting diode chip inside;
A heat pipe having one end connected to the package and enclosing a refrigerant therein;
A cooling device for a light emitting diode, comprising: a heat exchanger connected to the other end of the heat pipe to cool the refrigerant.   The light-emitting diode cooling device according to claim 3, wherein a flow path for the coolant is formed around the light-emitting diode chip in the package.   5. The light emitting diode cooling device according to claim 3, wherein the heat pipe is connected to a surface of the package opposite to a surface from which light emitted from the light emitting diode chip is emitted.

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