JP4582786B2 - Light source device - Google Patents

Description

  The present invention relates to a light source device, particularly a light source device using an LED element, and provides a high-intensity light source at a small size and at low cost.

Conventionally, LED lamps have been provided by LED manufacturers as surface mount type lamps using a bullet-type lead type or a resin package. However, these types are sufficient for conventional display applications using a small current, but are not suitable for use as a light source for illumination with a large current and high heat generation.
In recent years, development to increase the luminous efficiency of LED elements has been promoted, improvement of LED chip itself and improvement of heat dissipation by increasing the size of LED chip, and attaching a lens or reflector on the chip light emitting surface Improvements have been made to collect light.
As a result, the LED element having a luminous efficiency of 2 lm / W has reached an efficiency level exceeding 30 lm / W, and the application to lighting applications has been discussed.
The LED lamp is excellent in terms of environmental measures because it has low energy loss and is energy saving, and has a long lifetime, and expectations for lighting applications are increasing.
However, even when the above-described improved LED lamp is used, in order to realize a lighting fixture, the luminous flux is insufficient, and thus it is necessary to configure a device by mounting a plurality of LED elements.

  By the way, although there are a wide variety of lighting fixtures in one bite, it can be said in common that a high-performance lighting device is provided by providing a high-intensity light source as small as possible. It is uniquely named.

Certainly, if a lighting fixture is configured by mounting a plurality of LED elements, the amount of light can be adjusted depending on the number of LED elements. It can be said that the necessary fluorescent lamps can be substituted. However, since the amount of heat generation naturally increases, the conventional structure has a drawback in that the instrument becomes large. In particular, among lighting fixtures that require a large amount of light (projectors such as projectors), it is necessary to realize a high-luminance, high-luminous light source in a small size, and thus it is not possible to cope with fixture design using conventional LED element mounting technology. .
Therefore, at present, it is still realized that a light source used for a lighting apparatus that requires a large amount of light, such as a projector, is replaced with a conventional light source that can obtain a large amount of light (such as a xenon lamp or a mercury lamp), and a light source device including LED elements. It wasn't.

  Taking a projector as an example of a projector as an application of a high-intensity compact light source, it is required to produce a luminous flux of 1000 lm or more with a light emitting area of about 3 cm in diameter as a lighting fixture. In this case, even when a high-luminance LED element of 30 lm / W is used, 30 or more elements must be integrated and mounted, and as a future technology, an ultra-high-luminance element of 50 to 100 lm / W is tentatively developed However, 10 or more element mounting is required.

  In such a high-density element mounting, even a LED that is a solid light-emitting element with little energy loss has a considerable heat generation density. In the case of the projector described above, heat loss is several tens of watts.

  When the heat radiation is insufficient, the LED element has a problem that the light emission efficiency is greatly reduced due to a temperature rise due to heat generation and the LED element sealing resin is deteriorated. At this time, it is conceivable to control the output of the element in order to correct the light emission characteristics of the element to a certain level. However, in this case, there is a problem that the burden on the element is further increased and the life is shortened. It was. In addition, when a plurality of LED elements having different emission colors such as R, G, and B are used for mixed color mounting, the temperature dependent characteristics and the element lifetimes of the LED elements for each color of R, G, and B are different. There was a problem that the color developability (color rendering) would change.

As described above, in order to provide a high-luminance light source as small as possible, a configuration that can secure a stable heat radiation capability in addition to efficiently extracting a light beam is required.
Therefore, a conventionally known configuration of the LED light source device that is an object of the present invention will be examined from both the viewpoint of efficiently extracting a luminous flux and securing a stable heat dissipation capability.

First, considering the point of efficiently extracting the luminous flux, only the LED light source devices known so far have a configuration in which chips are densely arranged on a substrate plane (see Patent Documents 1 and 2). .
On the other hand, when only integration is considered, a technique of multilayering (four-layer, six-layer substrates, etc.) is frequently used for printed boards and the like. There is also an example in which components are arranged in multiple layers in addition to the substrate by incorporating components in the multilayer substrate.
However, as a method for efficiently extracting the luminous flux in the same direction, there have been no examples of attempts to arrange the light emitting element chips in a three-dimensional manner.

Next, in terms of securing stable heat dissipation capability, in recent years, in view of emphasizing heat dissipation, in some technical fields such as power modules, it has better thermal conductivity than substrates such as glass-based epoxy resin. Examples of using ceramic substrates and metal substrates are increasing.
However, in the configuration in which the chips are densely arranged on the substrate plane as described above, even if a metal substrate is used, if the output is increased, the heat dissipating capability will be insufficient immediately, so that the degree of integration cannot be improved as expected. was there.
In the past, metal substrates were used from the viewpoint of placing great importance on heat dissipation, but if sufficient heat dissipation capability could not be secured with a single metal substrate, the metal substrate could be attached to a housing such as a lighting device ( It has only been taken countermeasures by connecting to a chassis or a cover) or simply connecting a heat dissipation block to the back side of this metal substrate (see Patent Document 2).

In short, in addition to efficiently extracting the luminous flux in the same direction, a configuration capable of sufficiently ensuring the heat dissipation capability has not been provided so far.
JP 2004-327138 A JP 2004-55800 A

  Accordingly, an object of the present invention is to provide a light source device capable of sufficiently securing a heat radiation capability in addition to efficiently extracting a light beam in the same direction.

In order to improve the light emission density in a luminaire using an LED element as a light source, it can be said that as a method other than improving the light emission efficiency of the LED element itself, drastic innovation in the mounting method of the LED element is necessary. As a result of various studies aimed at the innovation in this mounting method and the solution of the above problems, the present inventor has achieved a new structure in which LED elements that have only been arranged on a conventional plane are arranged three-dimensionally. The above problems were solved.
That is, the present inventor has a heat dissipation efficiency that is doubled compared to a case where light emitting elements are mounted in a single layer at a high density because each layer has a heat dissipation effect if the substrate for heat dissipation has a multiple structure. The present invention was completed by finding that light emitting elements can be arranged at a narrow pitch or mounted at a high density without considering thermal interference between adjacent elements.

The light source device capable of solving the present invention the above problems, (1) comprises a substrate of a plurality of layers superposed multiple layers of substrates vertically, and a plurality of light emitting elements mounted on each of the substrate of the plurality of layers , wherein the upper layer side of the substrate out of the substrate a plurality of layers, which from the through-holes at positions corresponding to the mounting position of the light emitting element mounted on the lower substrate is provided, mounted on the uppermost layer of the substrate The light emitting element is disposed in a region excluding the through hole, and the light emitting element mounted on a lower layer substrate with respect to the uppermost substrate is accommodated in the through hole. Is. At this time, in the light source device, the light emitting element mounted on the lower substrate is accommodated in the through hole provided in the upper substrate on the two adjacent substrates.
As a result, the LED elements can be arranged and mounted at high density.

The present invention is further characterized in that, in the above light source device, (2) the opening area of the through hole is formed so as to expand upward.
Conventionally, a structure has been adopted in which a condensing lens or a reflector is provided on a mounting substrate of an LED element to increase the degree of condensing. However, because of the new structure of adding a lens and a reflector, it has caused problems of mounting accuracy and increased costs.
In the present invention (2), a structure in which the substrate itself has a light collecting effect has been devised, and these solutions have been obtained. That is, according to the present invention (2), since the side wall of the through hole of the substrate bears the light collecting effect, it is no longer necessary to add new components such as lenses and reflectors to the individual LED elements. .

Similarly, according to the present invention, in the light source device of (1) or (2), (3) the substrate is made of a metal base substrate or a ceramic substrate.
In mounting a high-brightness LED element that generates high heat, a substrate with high thermal conductivity is required to improve heat dissipation. Here, as a highly heat conductive wiring board, in addition to a metal base wiring board using aluminum or copper as a core for power modules, a wiring pattern is formed on a high heat conductive ceramic board such as alumina or aluminum nitride. A wiring board etc. are mentioned. However, those substrates have been conventionally used only as component mounting substrates.
The present invention (3) focuses on effective utilization of these high thermal conductivity substrates three-dimensionally. By forming the inclined through-hole in the high thermal conductivity substrate, it is possible to further improve the heat dissipation in addition to incorporating the above-mentioned light collecting function into the substrate itself.

Next, the present invention provides the light source device according to any one of (1) to (3), wherein (4) the light emitting element is mounted on the substrate with an electrode surface directed toward the substrate to be mounted. It is what.
In order to increase the mounting density of LED elements, it is not sufficient to mount a bullet-type LED lamp or a surface-mounted LED lamp, and it is necessary to mount the LED element in a bare chip state before resin molding. In the case of bare chip mounting, there are a face-up mounting method using a wire bond method and a face-down mounting method using a flip chip method.
Here, the face-up mounting method has a drawback that the light emitting area is reduced because the electrode for wire bonding connection is on the LED chip light emitting surface. Therefore, in order to improve the extraction efficiency of the light emitted from the LED element, a face-down mounting method in which an obstacle such as an electrode does not come to the light emitting surface is desirable.
According to the present invention (4), the LED chips can be mounted at a high density by mounting the LED chips on the metal base wiring board or the ceramic wiring board by using a flip chip method. It has become possible to further improve the take-out efficiency.

Further, the present invention is the light source device of (1) to (4) above, and (5) characterized in that it includes a heat radiation means that at least partly contacts the side surface of the substrate.
The present invention (5) is characterized in that heat dissipation in the side surface direction of the substrate is utilized to reduce the thermal resistance and downsize the product. According to the present invention (5), the side surface of the substrate can be effectively used to increase the heat radiation area, thereby improving the thermal diffusion efficiency.

In addition, the present invention is characterized in that in the light source devices of the above (1) to (5), (6) the substrate is mounted with light emitting elements having different emission colors for each layer. .
In luminaire applications that are often used as white light emitting units, the emission wavelength distribution is an important factor for color rendering.
In recent years, white LEDs using a combination of phosphors and blue or purple LED elements have been commercialized. However, in order to improve color rendering, the red component is insufficient, so it has been attempted to mix LEDs of multiple colors. Yes.
A problem in the case of mounting a plurality of color LEDs in a mixed manner is that correction control is difficult because the characteristics and changes over time differ for each color LED.
However, as in the case of the present invention (6), LED elements of different colors are allocated and mounted on each layer by utilizing the multiple structure of the substrate, and further, the output of the LED elements for each color allocated to each layer is converted to the LED of each color. By performing independent control according to the characteristics of the element, it is possible to realize stable high color rendering.
The color distribution to each layer is not necessarily limited to the three primary colors R, G, and B. Naturally, the present invention can be applied to two-color distribution such as a blue LED and a red LED, or a purple LED and a yellow LED, or a four-color distribution more than that.

  As described above, according to the present invention, it is possible to obtain an apparatus configuration capable of sufficiently ensuring the heat radiation capability in addition to efficiently extracting the light flux in the same direction.

  In the following, terms used for describing the present invention are defined.

“Flip chip bonding” refers to a technique for connecting a chip on which a bump is formed upside down to a substrate. The “bump” refers to a protruding electrode formed on the element surface of the semiconductor chip by vapor deposition, plating, printing, or the like.
The flip chip method maximizes the mounting density by using only bare chips and internal wiring without using a package. Gold and solder particles (bumps) are used without using wires for electrical connection. It is a mounting method that uses and connects.

“Thermal resistance” refers to an index representing heat dissipation characteristics of a semiconductor package or the like. This index is used for predicting the semiconductor element temperature (junction temperature) in a package under a certain cooling environment, or for cooling conditions of the package (wind speed, heat sink) to keep the semiconductor element temperature below a certain allowable temperature. Etc.). The index of thermal resistance gives a measure of heat dissipation of a package or the like. Thermal resistance can be measured using electrical parameters that affect the temperature of the device.
The value of the thermal resistance is not a constant value specific to the package or the like, but changes depending on the chip size, power consumption, mounting environment, and the like.
Further, the thermal resistance defines how much the temperature rises with respect to the electric power when the heat generated from the semiconductor chip is handled like a current flow. This thermal resistance is obtained by regarding the thermal circuit as an electrical circuit and converting the electrical conductivity into thermal conductivity.

The “metal base substrate” refers to a substrate in which a circuit pattern is formed on a base metal such as aluminum, iron, or copper via an organic insulating layer such as epoxy resin or polyimide. Also called a metal substrate, an insulating metal substrate, or a metal-based substrate. When a circuit is formed using a metal base substrate, the thermal resistance of the substrate is very small, so that a large power can be handled and heat generated in the wiring pattern can be efficiently radiated. In addition, since the entire circuit is on the metal substrate, unnecessary radiation radiated from the circuit can be significantly reduced by setting the metal portion to GND.
“Ceramic substrate” refers to a wiring substrate using alumina (Al ₂ O ₃ ) or another ceramic material as a substrate material. In general, a ceramic substrate has characteristics such as excellent thermal conductivity, electrical insulation, and heat resistance compared to other organic substrates.
“Directional characteristics” refers to light output measured by shifting the angle with respect to the main light emitting direction of the LED, and plotting the output at this time in a directional characteristic diagram. Directional characteristics are also called light distribution characteristics.

  In the prior art using an LED element, a light flux exceeding 1000 lm cannot be obtained with a light emitting area of about 3 cm in diameter. For example, even if a commercially available bullet-type or surface-mount high-power LED lamp with an element having a high luminous efficiency of about 30 lm / W is used, the rated output is low because the heat dissipation performance is low in the mounting method used normally. Usually limited to 100 mW or less. As a result, since the light output is limited to 3 lm at the maximum per LED, it is necessary to mount 334 or more LED lamps in order to realize a luminous flux exceeding 1000 lm. A high-output light source cannot be made.

  On the other hand, it is possible to improve the heat dissipation performance by replacing the substrate on which the LED lamp is mounted with a metal base wiring substrate having high thermal conductivity. However, since it is still limited by the thermal resistance of the substrate and the LED package, an LED element having a luminous efficiency of 30 lm / W class is used as an example that is realized, and about 10 pieces in a region having a diameter of about 10 cm. An LED element mounted is the best, and at present, only 200 to 300 lm of light flux can be obtained. In order to obtain a light source having a smaller size and a higher light output, there is no choice but to wait until an LED element with higher light emission efficiency is developed.

  According to the mounting technology and the heat dissipation technology of the present invention, it is possible to provide a high-efficiency and small-sized high-output light source without waiting for the future development of a high light-emitting efficiency LED element. According to one embodiment, in a light source module having a diameter of 3 cm (see the embodiment described later, see FIG. 4), 37 LED chips with a light emission efficiency of 30 lm / W are mounted and an output of 1 W per element is given. The element junction (joint) temperature at the center can be suppressed to about 49 ° C. (when forced cooling is used together). At this time, since the rated temperature of the LED element is well below the 80 ° C., it is possible to further increase the output. Therefore, it can be seen that a large luminous flux of 30 lm × 37 = 1110 lm or more can be obtained with a margin.

  According to the present invention, a light source having a small size and a large luminous flux can be obtained, so that a small projector, a powerful spot light source, or the like can be realized. In addition, because of the high output, it can be said that the LED light source device of the present invention can be applied in place of these high output lamps even in a field that conventionally requires a high output light source such as a xenon lamp or a mercury lamp.

  Hereinafter, the light source device of the present invention will be described in order with reference to the accompanying drawings. FIG. 1 is a diagram showing a first embodiment of a light source unit of the present invention, FIG. 2 is an enlarged view of a portion where an LED chip is mounted in the light source unit of FIG. 1, and FIG. 3 is a second diagram of the light source unit of the present invention. FIG. 4 is a view showing an embodiment, FIG. 4 is a view showing an embodiment of a light source module incorporating the light source unit of the present invention, and FIG. 5 is a view showing a modified embodiment of the light source module.

[First Embodiment]
First, an embodiment of a light source unit that is a basic component of the light source device of the present invention will be described in detail with reference to FIG. 1A is a plan view showing an embodiment of a light source unit according to the present invention, and FIG. 1B is a cross-sectional view taken along line AA ′ of FIG. 1A.

  As shown in FIG. 1, in this embodiment, an aluminum metal base substrate 1 having a diameter of 3 cm is used in two layers. This aluminum metal base substrate 1 has a structure in which a heat conductive insulating layer is formed with a thickness of 50 to 80 μm on a thin aluminum plate with a thickness of 2 mm, and a Cu foil on which a circuit pattern is formed is pressed. Have.

A 1 mm square LED chip C is mounted on the aluminum metal base substrate 11 of the first layer corresponding to the upper layer. In the first substrate layer 11, a through hole 4 is provided at a position corresponding to the arrangement position of the LED chip C mounted on the lower layer (second layer) aluminum metal base substrate 12.
Next, the LED chip C is mounted on the second-layer aluminum metal base substrate 12 at a position corresponding to the through hole 4 formed in the first substrate layer 11.
Thus, in this embodiment, the LED chip C mounted on the lower layer substrate 12 is accommodated in the through hole 4 provided in the upper layer substrate 11 of two adjacent substrates.

  In the first embodiment, an ultraviolet light emitting LED chip is mounted on both the substrate first layer 11 and the substrate second layer 12. The second-layer aluminum metal base substrate 12 is bonded to the first-layer aluminum metal base substrate 11 via a high thermal conductive adhesive layer.

  In the present embodiment, the LED chips C of the first layer 11 and the LED chips C of the second layer 12 are equally arranged in a grid lattice pattern in both layers so as to have a high density arrangement. As a result, the thermal diffusion efficiency is greatly increased by utilizing the multiple structure of the substrate. In the present embodiment, high-density mounting of LED chips is realized by the above configuration.

  Next, an enlarged view of the LED chip mounting portion is shown in FIG. 2A shows a case where the wall surface 5 of the through hole 4 is a vertical wall, and FIG. 2B shows a case where the wall surface 5 is inclined and the through hole 4 is formed so that the hole diameter expands upward.

  By the way, the through-hole 4 of the first layer 11 plays a role of a light reflecting plate with respect to the LED chip C of the second layer 12, and thus contributes to the luminous flux UP due to the condensing effect. When the through-hole 4 is formed so that the opening area expands upward as shown in FIG. 2B, it depends on the substrate material and the inclination angle of the wall surface 5, but compared with the vertical wall shown in FIG. 2A. Thus, it is possible to extract about twice as much light. This is considered to be because when the wall surface 5 of the through-hole 4 is considered as a reflection surface, the component of the irregularly reflected light is reduced when the wall surface 5 is inclined as compared with the case of the vertical wall.

As shown in FIG. 2, in this embodiment, the LED chip is mounted on the substrate 1 by a flip chip method (Au—Au bonding) using gold bumps. The electrode of the LED chip C faces the substrate 1 to be mounted, and is bonded to the wiring pattern 3 formed on the substrate 1 via the flip chip bonding portion 2. That is, the flip chip bonding portion 2 serves to electrically and mechanically connect the LED chip C and the substrate 1.
In the case of the flip chip method, there is no electrode or wire that obstructs light on the light emitting surface as compared with the mounting by the wire bond method, so that the effect of improving the light extraction efficiency by about twice can be obtained. Furthermore, in the case of the flip chip method, since the light emitting layer in the chip is close to the substrate side, the heat generated from the chip can be efficiently dissipated to the substrate, and the further effect of being useful for lowering the chip temperature is obtained.

  When a light source device is actually configured by attaching heat radiation fins to the light source unit 10 of this embodiment (see [Example] described later), a total of 37 ultraviolet light emitting LED chips having a light emission efficiency of 30 lm / W, a diameter of 3 cm. By high-density mounting on the upper and lower layers of the substrate, it becomes possible to obtain a light beam of 1110 lm at an output of 37 W.

[Second Embodiment]
Below, based on FIG. 3, it demonstrates per 2nd Embodiment of the light source unit 10 of this invention. FIG. 3A is a plan view showing a second embodiment of the light source unit of the present invention, and FIG. 3B is a sectional view taken along line BB ′ of FIG. 3A.
In this embodiment, the aluminum metal base substrate 1 having a diameter of 3 cm is used in three layers. The mounting structure of the LED chip C on each layer substrate is the same as that of the first embodiment, but the emission color of the LED chip C arranged in each layer 11 to 13 is different.

In the first embodiment, an example in which the LED chip C having the same emission color is used for the purpose of realizing a light source having a high density and a high luminous flux is shown. However, in this embodiment, LED chips C having different emission colors are used for the respective layers. . That is, in the present embodiment, among the three-layer substrates, LED chips of R, G, and B3 primary colors that are red for the substrate first layer 11, green for the substrate second layer 12, and blue for the substrate third layer 13. C was mounted, and the LED output in each layer was controlled independently.
In the present embodiment, the LED chips C in the substrate first layer 11 to the substrate third layer 13 are arranged in an equilateral triangular lattice so as to be in a close-packed arrangement. Even in such a configuration, the effect of increasing the thermal diffusion efficiency by using the multiple structure of the substrate can be obtained, and the LED chips C can be mounted at a high density.

By the way, the LED chip is a device having different emission characteristics depending on the emission color. This light emission characteristic varies depending on temperature and other environmental conditions. Therefore, in order to stabilize the light emission characteristics due to the color mixture of LED light emission colors, it is desirable to independently control the LED output for each color so that similar light emission characteristics can be obtained for each LED chip for each light emission color.
In this embodiment, as described above, LEDs having different emission colors are assigned to the respective layers, and the LED output is independently controlled for each layer. According to such a configuration, since the same heat dissipation characteristic and thus the temperature characteristic can be obtained in each layer, a stable light emission characteristic and emission color can be realized.

  In the present embodiment, the LED chips C are mounted at a ratio of 1: 1: 1 for each layer, but it is not always necessary to mount them at this ratio. For example, the number of blue chips may be reduced from the aspect of color rendering considering the recognizability of the emitted color. As described above, the number of LED chips of each layer emission color may be appropriately adjusted according to the required color rendering properties.

  Hereinafter, an example in which an illumination device is actually configured using the light source unit described above will be described. FIG. 4 shows an embodiment of the light source device (light source module) of the present invention. In the present embodiment, the light source unit 10 having the basic configuration uses the one shown in FIG. 4A is a plan view showing an embodiment of the light source module of the present invention, FIG. 4B is a side view of the light source module shown in FIG. 4A, and FIG. 4C is a cross-sectional view taken along line C-C ′ of FIG.

In the present embodiment, the light source module 20 includes a light source unit 10, a radiating fin housing 22 that accommodates the light source unit 10, and a control circuit board 26 for controlling the light source unit 10. The heat radiating fin housing 22 configured to cover the side surface and the lower portion of the light source unit 10 is manufactured by aluminum die casting. The heat radiating fins 21 of the heat radiating fin housing 22 are provided substantially radially with a certain angular interval, and are configured to be in contact with at least a part of the side surface of the light source unit 10. Each layer substrate (the substrate first layer 11 and the substrate second layer 12) of the light source unit 10 is bonded by a high thermal conductive adhesive. The LED driving wiring circuit formed on each layer substrate of the light source unit 10 is connected to the control circuit substrate 26 via the extraction electrode lead 25.
In this embodiment, the phosphor resin layer 23 and the condenser lens 24 are disposed on the front surface of the light source unit 10. The phosphor resin of the phosphor resin layer 23 is made of a transparent resin mixed with a phosphor in order to adjust the wavelength of light emitted from the LED. The condensing lens 24 is provided to distribute the total luminous flux extracted from the light source unit 10.

The light source module 20 of the present embodiment is an integrated control circuit board 26. The control circuit board 26 is installed below the light source unit 10. The lead electrode lead 25 is connected to a control IC 27 placed on the control circuit board 26. Output control of each LED chip C mounted on each layer substrate is performed by this control IC 27.
The lead electrode leads 25 can be freely drawn from the light source unit 10, and there are no particular restrictions on the lead lead positions and the number of leads. Therefore, by increasing the number of leads, for example, by mounting a thermistor element on each layer substrate and performing temperature detection or the like, it is possible to perform light control with higher accuracy.

According to this embodiment, 37 LED chips C having a light emission efficiency of 30 lm / W are mounted, and forced air cooling with a cooling fan (cooling temperature 25 ° C.) is used in combination with an output of 1 W per element. As a result, the element junction temperature at the center of the light source can be suppressed to about 65 ° C. At this time, since the rated temperature of the LED element is lower than 80 ° C., it is possible to further increase the output, and it can be seen that a large luminous flux of 30 lm × 37 = 1110 lm or more can be obtained with a margin.
Even in the case of natural heat dissipation, it is possible to extract a much larger amount of light flux than in the past.
Thus, according to the present embodiment, it is possible to provide a light source having a sufficiently high brightness while being extremely small. If the light source module of this embodiment is used, for example, a pocket-sized small projector can be configured.

Furthermore, if a cover is attached so as to cover the entire radiation fin housing 22 shown in FIG. 4 and a water cooling method using a flow path between the radiation fins 21 is adopted, the element junction temperature is reduced to about 49 ° C. It becomes possible to suppress.
A specific example of the water cooling system is a configuration in which water can enter and exit from the cover and the water is circulated by a micropump. In this case, it is preferable that water discharged from the cover is passed through a radiator installed in a casing (chassis or cover) of the lighting device, and finally heat is released from the radiator to the chassis.
In this way, if the water cooling method is adopted, it is possible to raise the output of each element to nearly twice that of air cooling even when considering use within the LED operating temperature rating. In this case, since a maximum light flux of about 2000 to 2500 lm can be obtained, it can be used as a light source for a commercial projector, and can be expected to be used for a wide range of applications.

[Modification]
Although the present invention has been specifically described with reference to various embodiments and the like, the present invention is not limited to the configurations described in the various embodiments and the like, and various design changes are possible.
For example, a projector is given as an example of an application to which the light source device of the present invention can be applied. However, the projector can be applied to various applications such as spotlights and automobile headlights that require small size and high integration.

About the through-hole 4, a shape is not restricted to a circular hole, A desired hole shape, such as an ellipse and a polygon, can be selected. The hole shape may be changed for each layer in accordance with the directivity characteristics of the LEDs arranged in each layer. There is no particular limitation on the specific shape of each through-hole, such as a shape in which the hole shape is continuously deformed from the bottom to the top (for example, from a circle to an ellipse).
When the through hole 4 is formed so that the opening area expands upward, the angle at which the wall surface 5 of the through hole 4 is inclined may be appropriately adjusted according to the actual application example. Generally, it is considered that the light extraction efficiency improves as the reflection area increases.
Further, the wall surface 5 of the through hole 4 may be plated to improve the characteristics as a reflection plate in the same manner as the through hole of the printed wiring board, so that the light extraction efficiency can be further improved.
Alternatively, the metal base substrate itself and the inclined wall surface portion 5 of the through-hole 4 may be made of a metal material having an optimum reflection characteristic in accordance with the color of light emitted from the LED chip and other characteristics.
In addition, in each of the above embodiments, the inclined wall surface 5 of the through hole 4 has a substantially linear inclination in a side sectional view, but this is curved so that the entire inner wall 5 of the through hole 4 is substantially parabolic. You may form so that a surface may be made.

  In the configuration of FIG. 4, the phosphor resin layer 23 and the condensing lens 24 are disposed on the front surface of the light source unit 10, but conventionally known configurations can be appropriately employed for these specific configurations. There is no particular limitation on the characteristics of the phosphor. Any one or all of these may be omitted. Furthermore, a configuration in which a diffusion plate or the like is disposed on the front surface of the light source unit may be used.

The heat dissipating fins 21 are not limited to the configuration in which the fins as illustrated in FIG. 4 are erected in a radial manner, and a plurality of thin annular fins are arranged along the side surface of the light source unit 10 and on the substrate. A configuration may be employed in which the gaps are stacked in the stacking direction (see FIG. 5). 5A is a plan view showing a modified embodiment of the light source module of the present invention, FIG. 5B is a side view of the light source module shown in FIG. 5A, and FIG. 5C is a cross-sectional view taken along the line CC ′ of FIG.
The arrangement position of the air cooling fan is not particularly limited. For example, the fan may be arranged at the position of the control circuit board 26 in FIG. 4 and the control circuit board 26 may be arranged at another position.

In each of the above embodiments and the like, each layer substrate constituting the light source unit 10 is made of an aluminum metal base substrate, but the substrate material is not limited to this, and may be copper or other thermally conductive metal. Alternatively, a highly thermally conductive ceramic substrate made of alumina, aluminum nitride, silicon nitride, or the like may be used.
In each of the above embodiments, each LED chip C is connected to the substrate 1 by a flip chip method using gold bumps, but the flip chip bonding method is limited to Au-Au bonding using gold bumps. Alternatively, various methods such as a connection method using metal bonding typified by the C4 method and Au-solder method, or a connection method using contact bonding typified by the ACF method and the NCP method may be adopted.

In addition, in each of the above-described embodiments and the like, the example in which the LED chips C are equally arranged on the substrate in a grid lattice shape or a regular triangle lattice shape has been described. However, the specific arrangement method of the LED chips C in each layer is not particularly limited. Alternatively, the LED chips C may be arranged radially or in an annular shape. The number of LED chips mounted is not limited depending on the arrangement.
The light extraction direction is not limited to the stacking direction of the substrates, and a configuration in which the extraction direction is changed may be used.
In each of the above embodiments and the like, the configuration of the light source unit 10 in which two or three layers of substrates are stacked has been described. However, the number of stacked layers is not particularly limited, and for example, a configuration of four or more layers may be adopted as appropriate. The substrate shape is not limited to a disk shape.
There is no particular limitation on the type, emission color, directivity, etc. of the LED chip C.
Further, in each of the above examples, the light emitting element has been described as an LED, but it goes without saying that the present invention is sufficiently applicable to EL and other small light emitting elements that are expected to be developed in the future.

  As described above, the present invention is novel and useful in which elements and substrates are formed in multiple layers from the viewpoint of ensuring sufficient heat dissipation capability in addition to efficiently extracting light beams in the same direction.

It is a figure which shows 1st Embodiment of the light source unit of this invention. It is the figure which expanded the part in which the LED chip is mounted in the light source unit of FIG. It is a figure which shows 2nd Embodiment of the light source unit of this invention. It is a figure which shows one Example of the light source module incorporating the light source unit of this invention. It is a figure which shows the modification Example of a light source module.

Explanation of symbols

C Light-Emitting Element Chip 1 Substrate 2 Flip Chip Junction 3 Wiring Pattern 4 Through Hole 5 Wall Surface 10 Light Source Unit 11 Substrate First Layer 12 Substrate Second Layer 13 Substrate Third Layer 20 Light Source Module 21 Radiation Fin 22 Radiation Fin Housing 23 Fluorescence Body resin layer 24 Condensing lens 25 Lead electrode lead 26 Control circuit board 27 Control IC

Claims (6)

A substrate of a plurality of layers superposed multiple layers of the substrate up and down,
A plurality of light emitting elements mounted on each of the plurality of layers of substrates ;
With
A through hole is provided at a position corresponding to the mounting position of the light emitting element mounted on the lower layer substrate in the upper layer side substrate among the multiple layer substrates ,
The light emitting element mounted on the uppermost substrate is disposed in a region excluding the through hole, and the light emitting element mounted on a lower layer substrate with respect to the uppermost substrate is accommodated in the through hole. light source and wherein the are.   The light source device according to claim 1, wherein an opening area of the through hole is formed to expand upward.   The light source device according to claim 1, wherein the substrate is made of a metal base substrate or a ceramic substrate.   4. The light source device according to claim 1, wherein the light emitting element is mounted on the substrate with an electrode surface directed toward a substrate on which the light emitting element is mounted.   5. The light source device according to claim 1, further comprising a heat radiating unit at least partially contacting a side surface of the substrate.   6. The LED light source device according to claim 1, wherein light emitting elements having different emission colors are mounted on the substrate for each layer.

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