JP2024036172A - light source device - Google Patents

Abstract

The present invention provides a light source device that can improve the uniformity of light output between a plurality of light emitting elements. A light source device includes a substrate with a plurality of light emitting elements arranged on one main surface, and a cooling plate that is joined to the other main surface of the substrate and includes a spiral flow path through which a coolant flows. The cooling plate includes an inlet for the refrigerant, an outlet for the refrigerant, and a first flow path connected to the inlet, through which the refrigerant flows from outside to inward of the cooling plate. a second flow path connected to the first flow path and the outlet, through which the refrigerant that has passed through the first flow path flows from inside to outside of the cooling plate; The channels are arranged alternately from the outside to the inside of the cooling plate. [Selection diagram] Figure 2

Description

The present invention relates to a light source device.

2. Description of the Related Art Light source devices using multiple light emitting elements such as LEDs and LDs are used in various fields. The light emitting element generates heat as it emits light. When the temperature of the light emitting element increases due to heat generation, the luminous efficiency of the light emitting element decreases. Therefore, it is known to bond a substrate on which a plurality of light emitting elements are arranged to a cooling plate to suppress the temperature rise of the light emitting elements (see Patent Document 1).

By the way, if we shift our focus to semiconductor devices other than light emitting devices, there are various types of cooling mechanisms for semiconductor devices. 2. Description of the Related Art There is a known method of cooling a power semiconductor element by stacking the power semiconductor element in many layers so as to sandwich the power semiconductor element between cooling plates having channels through which a coolant flows (see Patent Document 2).

Japanese Patent Application Publication No. 2019-175871 Japanese Patent Application Publication No. 7-307423

A light source device using a plurality of light emitting elements such as LEDs and LDs is also used for drying printing ink, adhering electronic components with ultraviolet curable resin, or exposing photosensitive resists. In these technical fields, the market demands uniform illuminance on the irradiated surface of the light source device. In order to achieve uniform illuminance, it is necessary to equalize the light output between the plurality of light emitting elements.

Therefore, it is an object of the present invention to provide a light source device that can improve the uniformity of light output between a plurality of light emitting elements.

The present inventor has focused on the fact that the temperature of a light emitting element affects the light output of the light emitting element, and has considered increasing the uniformity of the light output by making the temperature uniform between the light emitting elements. As a result of intensive research by the present inventors, the inventor came up with the idea of optimizing the design of a cooling plate that is in contact with a substrate on which a plurality of light emitting elements are arranged, in order to equalize the temperature among the light emitting elements, and devised the following light source device.

The light source device of the present invention includes a substrate having a plurality of light emitting elements arranged on one main surface, and a cooling plate that is joined to the other main surface of the substrate and includes a spiral flow path through which a coolant flows. , comprising:
The cooling plate is
the refrigerant inlet;
an outlet for the refrigerant;
a first flow path connected to the inlet and through which the refrigerant flows from outside to inside of the cooling plate;
a second flow path connected to the first flow path and the outlet, through which the refrigerant that has passed through the first flow path flows from the inside to the outside of the cooling plate;
The first flow path and the second flow path are alternately arranged from the outside to the inside of the cooling plate.

First, terms used in this specification will be explained. In this specification, the term "principal surface" refers to a surface that is much larger in area than other surfaces among the surfaces constituting a plate-shaped object. In this specification, a "substrate" and a "cooling plate" that are plate-shaped objects each have two opposing main surfaces.

In this specification, when simply expressed as a "flow path", the "flow path" includes a "first flow path" and a "second flow path".

In addition to directly joining the substrate and the cooling plate without using any other material, a thermally conductive material such as thermally conductive grease may be interposed between the substrate and the cooling plate. In this specification, such a "thermally conductive material" is treated as a part of the cooling plate.

In the light source device described above, a cooling plate is bonded to the main surface of the substrate on which the plurality of light emitting elements are arranged, which is opposite to the main surface on which the light emitting elements are arranged. Thereby, the plurality of light emitting elements can be cooled while extracting light from the plurality of light emitting elements. Furthermore, since the intervals between each light emitting element and the cooling plate are uniform, a more uniform cooling effect can be obtained for each light emitting element.

However, if a cooling plate is analyzed in more detail, in the case of a cooling plate that includes channels through which a refrigerant flows, the cooling effect of the cooling plate differs locally depending on the arrangement of the channels. In particular, the refrigerant near the inlet has not yet absorbed heat, so its temperature is relatively low and the cooling effect is large. On the other hand, the refrigerant near the outlet has already absorbed a lot of heat, so its temperature is relatively high and the cooling effect is small. Therefore, a light emitting element near the first flow path near the inlet is more easily cooled than a light emitting element near the second flow path near the outlet, and this difference in cooling effect may result in a difference in light output of the light emitting elements. be.

In the light source device, the first channel close to the inlet and the second channel close to the outlet are alternately arranged from the outside to the inside of the cooling plate. As a result, in the cooling plate, heat transfer occurs from the refrigerant in the second flow path to the refrigerant in the first flow path, and the temperature difference between the refrigerant flowing in the first flow path and the refrigerant flowing in the second flow path becomes small. As a result, the temperature of the cooling plate becomes more uniform, and the plurality of light emitting elements can be cooled more evenly.

The first flow path and the second flow path are
partitioned by a first strip located on the left side of the first flow path and the second flow path in the direction in which the refrigerant travels; and a second strip located on the right side of the first flow path and the second flow path in the direction of travel of the refrigerant. It doesn't matter if it is. As used herein, "strip" refers to a thin, elongated, strip-like object. The two strips define a first flow path and a second flow path.

In a connection region where the first channel connects to the second channel, the first strip and the second strip each have an end,
At least one of the ends may have a rounded shape when viewed from the normal direction of the main surface of the cooling plate. This makes it difficult for the refrigerant to become turbulent, improving cooling efficiency.

In the spiral flow path, the width of the flow path may be larger than the thickness of the flow path. When the channel width is larger than the channel thickness, the amount of refrigerant can be increased and the cooling efficiency can be improved even though the thickness of the cooling plate is limited.

When the sum of the thickness of the substrate and the thickness of the base of the cooling plate is t, the pitch of the flow path is Pw, and the dimension of the light emitting element is L1, equation (1) may be satisfied. Although the details will be described later, by designing the dimensions of the cooling plate as described above, it is possible to suppress the influence of the difference in cooling efficiency due to the temperature difference of the coolant between the first flow path 35a and the second flow path 35b on the heat absorption of the light emitting element. I can do it.

The pitch Pw of the flow paths may be less than or equal to the pitch _PL of the light emitting elements.

In the spiral channel portion, the channel width of the first channel may be substantially the same as the channel width of the second channel. "Substantially the same" indicates that the difference (absolute value) between the channel width of the first channel and the channel width of the second channel is within 10% of the channel width of the first channel. In addition, it is more preferable that the difference (absolute value) between the channel width of the first channel and the channel width of the second channel is within 5%, and is within 3%. and even more preferable.

The inlet may be located at a distance from the outlet so that heat conduction from the outlet is suppressed. The refrigerant flowing in the first flow path near the inlet is suppressed from receiving heat from the refrigerant flowing in the second flow path near the outlet. This can prevent the coolant flowing through the first flow path near the inlet from absorbing heat that does not contribute to lowering the temperature of the light emitting element. As a result, effective cooling can be performed.

A power supply unit that supplies power to the light emitting element may overlap an area without the flow path on the main surface of the cooling plate. The cooling plate has a region with a flow path and a region without a flow path. By allowing the power supply section to overlap an area without a flow path, the flow path can be arranged to give priority to cooling of the light emitting element. As a result, effective cooling can be performed.

The cooling plate may include a main body and a lid, and the main body may be made of a solid metal plate. Here, the main body may be joined to the substrate on which the light emitting element is arranged, or the lid body may be joined to the substrate on which the light emitting element is arranged. The material of the strip defining the flow path may be the same as the material of the base joined to the other surface of the substrate. As an example, the strips and base that constitute the main body of the cooling plate are formed by cutting out a single metal plate. This eliminates material joints within the body, increasing the strength and thermal conductivity of the body.

A light source device that can improve the uniformity of light output between a plurality of light emitting elements can be provided.

It is a perspective view of the light source device of a first embodiment. It is a perspective view of the light source device of a first embodiment. FIG. 3 is a view of the main body of the cooling plate viewed from the -Z side of the cooling plate. FIG. 4 is an enlarged view of the connection area between the first flow path and the second flow path in FIG. 3; It is a figure which shows the reference form of the connection area of a 1st flow path and a 2nd flow path. It is a sectional view of the light source device of a first embodiment. FIG. 3 is a view of the light source device viewed from the +Z side in the normal direction of the main surface of the substrate. FIG. 6 is a view showing the main body of the cooling plate where the inlet is close to the outlet. It is a figure which shows the main body of the cooling plate of 2nd embodiment. It is a sectional view of a light source device of a third embodiment. It is a sectional view of a light source device of a fourth embodiment.

Each embodiment of the light source device will be described with reference to the drawings. Note that each drawing disclosed in this specification is merely schematically illustrated. That is, the dimensional ratios on the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios do not necessarily match between the drawings.

The drawings are described with reference to an XYZ coordinate system. In this specification, when expressing directions, when distinguishing between positive and negative directions, they are described with positive and negative signs, such as "+X direction" and "-X direction." Furthermore, when expressing a direction without distinguishing between positive and negative directions, it is simply written as "X direction." That is, in this specification, when the term "X direction" is simply used, it includes both the "+X direction" and the "-X direction." The same applies to the Y direction and the Z direction.

<First embodiment>
[Overview of light source device]
A first embodiment of a light source device will be described with reference to FIG. FIG. 1 is a perspective view of a light source device 100. As shown in FIG. 1, the light source device 100 includes a substrate 10 and a cooling plate 30. The main surface of the substrate 10 and the main surface of the cooling plate 30 are each shown extending along the XY plane. The thickness direction of the substrate 10 and the cooling plate 30 is shown in the Z direction.

A plurality of light emitting elements 2 are arranged on one main surface of the substrate 10. In FIG. 1, one of the plurality of light emitting elements 2 is designated by the symbol "2". Although details will be described later, the plurality of light emitting elements 2 of this embodiment are arranged at equal pitches. Specifically, on the substrate 10, adjacent light emitting elements 2 are arranged at six points around one light emitting element 2 and equidistant from the one light emitting element 2. The light emitting elements 2 arranged at six points constitute the vertices of a regular hexagon. As a result, the light emitting elements 2 are arranged at equal pitches on the XY plane. However, the plurality of light emitting elements 2 do not necessarily have to be arranged so as to constitute the vertices of a regular hexagon. For example, the plurality of light emitting elements 2 may be arranged to constitute the vertices of a square. Furthermore, the plurality of light emitting elements 2 do not have to be arranged at equal pitches. For example, the plurality of light emitting elements 2 may be arranged to constitute vertices of a polygon that is not a regular polygon (a hexagon that is not a regular hexagon, a rectangle, etc.).

A cooling plate 30 is bonded to the other main surface of the substrate 10. The cooling plate 30 includes therein a flow path through which a refrigerant flows. Details of the flow path will be described later. The refrigerant is supplied from the supply pipe 41 to the cooling plate 30 , passes through a flow path inside the cooling plate 30 , and is discharged from the cooling plate 30 to the discharge pipe 42 . The supply pipe 41 and the discharge pipe 42 are not included in the light source device 100. The cooling plate 30 includes a main body 30a and a lid 30b joined to the main body 30a. Although details will be described later, a flow path is formed inside by joining the main body 30a and the lid 30b.

Light from the light emitting element 2 is emitted in the +Z direction. When the light emitting element 2 is viewed from the emission side (+Z side) in the -Z direction, the light emitting element 2 has a square shape. However, the shape of the light emitting element 2 is not particularly limited, and may be rectangular, circular, or elliptical, for example. The light emitting element 2 is not limited to a chip type light emitting element in which a plurality of light emitting elements are mounted on a substrate as shown in FIG. 1. For example, a single light emitting element or a package type light emitting element in which a plurality of light emitting element groups are packaged may be used. The dimension L1 of the light emitting element 2 is not particularly limited, but in the case of a chip type, it may be, for example, 0.3 mm or more and 3 mm or less, and in the case of a package type, it may be 1 mm or more and 15 mm or less. Note that the dimension L1 of the light emitting element 2 is expressed by the length of the longest side or the maximum diameter of the light emitting element 2.

The light emitting device 2 is preferably a solid state light emitting device. In this embodiment, the light emitting element 2 is an LED, but a semiconductor laser element (LD) may also be used as the light emitting element 2. The emission wavelength of the light emitting element 2 is not particularly limited, and for example, visible light, ultraviolet light, or infrared light may be emitted.

Regardless of whether the light emitting elements 2 are of a chip type or a package type, the number of light emitting elements 2 arranged on the substrate 10 is not particularly limited. In both cases, the total number of light emitting elements 2 mounted on the substrate bonded to one cooling plate may be 20 or more, preferably 50 or more, and more preferably 100 or more. Good to have. The number of light emitting elements 2 arranged on the substrate 10 may be 5000 or less, preferably 1000 or less, and more preferably 500 or less.

The dimensions of the substrate 10 to be joined to one cooling plate are preferably 50 mm or more in each of the X and Y directions, and more preferably 80 mm or more. The dimensions of the substrate 10 are preferably 500 mm or less in each of the X and Y directions, and more preferably 200 mm or less.

The light source device 100 includes a power supply section 5 for supplying power to each of the light emitting elements 2. In this embodiment, the power supply section 5 is a power supply connector configured to be connectable to an external power source. The light source device 100 includes four power supply units 5 so that power can be shared and supplied to the plurality of light emitting elements 2 that constitute the light source device 100.

FIG. 2 is a perspective view of the light source device 100. However, FIG. 2 shows a state in which the lid 30b is removed so that the flow path 35 can be confirmed. The main body 30a of the cooling plate 30 has a refrigerant inlet 31 and a refrigerant outlet 32. The inlet 31 is connected to the supply pipe 41 and the outlet 32 is connected to the discharge pipe 42. The refrigerant used is not limited. The refrigerant is preferably a liquid, for example water. However, the refrigerant may be a liquid other than water. The refrigerant may be a liquid containing gas. The refrigerant may be a gas.

FIG. 3 is a view of the main body 30a viewed from the −Z side of the cooling plate 30 in the +Z direction along the normal to the main surface of the cooling plate 30. In order to make it easier to recognize the inlet 31, the outlet 32, and the flow path 35, hatching is applied to areas where water does not flow. Similar hatching is applied to FIGS. 4A, 4B, 7, and 8, which will be described later.

[Spiral-like flow path]
The flow path 35 will be explained with reference to FIG. The flow path 35 has a first flow path 35a connected to the inlet 31 and a second flow path 35b connected to the outlet 32. Most of the flow path 35 except for the vicinity of the inlet 31 and the outlet 32 has a spiral shape. The first flow path 35a includes a portion where the refrigerant flows from the outside to the inside of the cooling plate 30, and the second flow path 35b includes a portion where the refrigerant flows from the inside of the cooling plate 30 toward the outside. The first flow path 35a is connected to the second flow path 35b at point P1. Point P1 can be said to be the center point of the spiral.

The first flow path 35a and the second flow path 35b are arranged alternately from outside the cooling plate 30 toward the center point P1. The reason for this will be explained. The refrigerant flowing through the flow path 35 absorbs more heat and becomes hotter as it goes downstream. Therefore, the refrigerant flowing through the second flow path 35b tends to have a higher temperature than the refrigerant flowing through the first flow path 35a. However, when the first flow path 35a and the second flow path 35b are arranged alternately, heat transfer occurs from the refrigerant in the second flow path 35b to the refrigerant in the first flow path 35a, and the refrigerant flowing in the first flow path 35a The temperature difference of the refrigerant flowing through the second flow path 35b becomes smaller. When the temperature difference between the coolant flowing through the two channels (35a, 35b) becomes smaller, the substrate 10 bonded to the cooling plate 30 and, by extension, the plurality of light emitting elements 2 can be evenly cooled.

As shown in FIG. 3, when the main body 30a is viewed from the −Z side of the cooling plate 30 in the +Z direction, the spiral flow path 35 is a generally circular (or approximately elliptical) spiral with no corners as a whole. exhibits a condition. Since the spiral flow path 35 has no corners as a whole, the refrigerant can flow smoothly. However, the spiral flow path may have a shape (for example, a polygon) including an angular portion as a whole.

The first flow path 35a and the second flow path 35b are formed by being partitioned by a thin and long spiral strip. As shown in FIG. 3, the strips include a first strip 36 located on the left side of the first flow path 35a and the second flow path 35b in the traveling direction (left side with respect to the refrigerant traveling direction), and a first strip 36 located on the left side of the first flow path 35a and the second flow path 35b (left side with respect to the refrigerant traveling direction); A second strip 37 is located on the right side of the second flow path 35b in the traveling direction (right side with respect to the direction in which the refrigerant travels).

As shown in FIG. 3, the first strip 36 and the second strip 37 each protrude from a portion of the main body 30a and have a shape wound around the center point P1. The first strip 36 and the second strip 37 define a first flow path 35a and a second flow path 35b. Note that the flow path 35 may be divided by three or more strips. For example, the strips may be arranged so as to provide two sets of inflow ports 31 and outflow ports 32.

FIG. 4A is an enlarged view of the connection region C1 in FIG. 3 where the first flow path 35a connects to the second flow path 35b. The first strip 36 has an end 36e in the connection region C1. The second strip 37 has an end 37e in the connection area C1. The center point P1 of the spiral of the flow path (35a, 35b) is located at the midpoint of the line segment LS connecting the end portion 36e and the end portion 37e.

The two ends (36e, 37e) are both rounded and have no corners. When the end portion is square (FIG. 4B), the flow of the refrigerant changes its direction sharply and tends to become turbulent. On the other hand, in the case of the rounded ends (36e, 37e) shown in FIG. 4A, the flow of the refrigerant changes its direction smoothly and is less likely to become turbulent.

The channel width Wn is defined as the width of the first strip 36 and the second strip 37 on a line LO perpendicular to the intermediate line LI that is equidistant from the first strip 36 and the second strip 37 that are arranged opposite to form the channel 35. It is represented by the spacing of the strips 37. It is preferable that the deviation in channel width is smaller. If the deviation in channel width is large, the flow velocity increases where the channel width is narrow and the flow velocity decreases where the channel width is wide, which tends to cause turbulence. On the other hand, when the deviation of the channel width is small, the flow velocity becomes constant and turbulence is less likely to occur.

In FIG. 4A, W1, W2, and W3 are all channel widths. The smaller the deviation of the channel widths (W1, W2, W3) (the difference between the channel width at each position and the average channel width Wx), the better. The roundness of the ends (36e, 37e) reduces deviation in channel width. Note that the average channel width Wx is determined by the average value obtained by measuring the channel width at a plurality of locations (for example, five locations) in the channel of the spiral portion.

FIG. 4B is a reference form of the flow path shape in the connection region C1. In FIG. 4B, unlike in FIG. 4A, the end 36e of the first strip 36 and the end 37e of the second strip 37 have corners. When the ends (36e, 37e) have corners, the channel width changes with respect to the direction in which the refrigerant flows. In other words, the deviation in channel width becomes larger than in the case of FIG. 4A. Therefore, in the connection region C1 shown in FIG. 4B, the refrigerant is more likely to flow turbulently than in FIG. 4A.

It is preferable that the channel width is constant not only in the connection region C1 but also in the entire first channel 35a and second channel 35b. The width of the first flow path 35a is preferably approximately the same as the width of the second flow path 35b. In the spiral channel portion, the deviation in channel width is preferably within 5 mm, more preferably within 3 mm, and even more preferably within 1 mm.

Either one of the end 37e of the second strip 37 and the end 36e of the first strip 36 may have a rounded shape.

FIG. 5 is an enlarged cross-sectional view of a portion of the light source device 100. As shown in FIG. FIG. 5 is a cross-sectional view taken on a plane perpendicular to the main surface of the cooling plate 30 and perpendicular to the direction of movement of the coolant in the flow path 35.

As shown in FIG. 5, the main body 30a of the cooling plate 30 includes strips (36, 37) and base portions 30d of the strips (36, 37) in the thickness direction. In this embodiment, the main body 30a is made of a solid metal plate. That is, the strips (36, 37) and the base portion 30d of the strips (36, 37) are formed by cutting out a single metal plate. Therefore, since the strips (36, 37) and the base 30d are made of the same material, there is no difference in thermal expansion between them, and they are not subject to thermal distortion due to the difference in thermal expansion. Furthermore, since there is no joint between the strips (36, 37) and the base 30d, there is no decrease in strength at the joint, and the heat of the substrate 10 is easily conducted to the cooling plate 30.

The main body 30a of the cooling plate 30 may be manufactured using other methods. In the main body 30a, for example, the first strip 36 and the second strip 37 may be joined to the base 30d by welding, adhesive, or the like. A groove into which the first strip 36 and the second strip 37 are fitted may be formed in the base 30d, and the main body 30a may be constructed by fitting the first strip 36 and the second strip 37 into the groove. The first strip 36, the second strip 37, and the base portion 30d may be formed by a 3D modeling method.

The method for forming the main body 30a described above may be applied to the lid 30b of the cooling plate 30. In FIG. 5, the main body 30a having strips (36, 37) is bonded to the substrate 10, but the present invention is not limited thereto. Instead of the main body 30a, a lid 30b without strips (36, 37) may be joined to the substrate 10.

The channel thickness H2 is smaller than the channel width W4. That is, by relatively narrowing the interval between each flow path, it is easy to maintain heat transport between the flow paths. For example, as shown in Figure 5, by making the cross section of the flow channel flat, the width of the flow channel is expanded to promote heat transport, while the thickness H2 of the flow channel is made relatively small, allowing the heat to be transferred between the flow channels. Easy to maintain transportation. Further, the cross-sectional shape forming the flow path 35 can be any shape such as a circle. However, from the viewpoint of promoting heat transport between the channels, it is desirable that the first strip 36 and the second strip 37 separating the channels have a flat shape in a direction perpendicular to the main surface. Furthermore, it is desirable that the flow paths formed by the first strip 36 and the second strip 37 be formed at equal intervals.

When the total thickness of the thickness T1 of the substrate 10 and the thickness T3 of the base 30d of the cooling plate 30 is t, the pitch of the flow path 35 is Pw, and the dimension of the light emitting element 2 is L1, the light source device 100 calculates the equation (1). It doesn't matter if you fill it.

The heat of each light emitting element 2 is diffused in the −Z direction and simultaneously in the ±Y direction. As the total thickness t increases, heat diffuses in the ±Y direction. When formula (1) is satisfied, the diffusion of heat in the ±Y direction expands beyond the pitch Pw of the flow paths 35. As a result, the heat generated in any of the light emitting elements 2 diffuses in the ±Y direction, reaches the two adjacent channels (first channel 35a and second channel 35b), and flows through the first channel 35a. It is absorbed by both the refrigerant and the refrigerant flowing through the second flow path 35b. Such dimensional design can suppress the influence of the difference in cooling efficiency due to the temperature difference between the coolant in the first flow path 35a and the second flow path 35b on the heat absorption of the light emitting element 2. The total thickness t is preferably 1.8 mm or more, for example.

The light source device 100 may further satisfy equation (2).

In order to suppress the influence of the difference in cooling efficiency due to the temperature difference between the coolant in the first flow path 35a and the second flow path 35b on the heat absorption of the light emitting elements 2, the heat from each light emitting element 2 must be It is sufficient that the total thickness t is such that it is diffused throughout the channels (the first channel 35a and the second channel 35b). Further, as the total thickness t increases, the cost increases and the space is occupied. Therefore, if the light source device 100 is designed so that the total thickness satisfies equation (2), it can be effectively cooled. The total thickness t may be, for example, 4.7 mm or less.

The pitch Pw of the flow paths 35 may be equal to or less than the pitch P _L of the light emitting elements 2 (see FIG. 5). The pitch Pw of the flow paths 35 is, for example, 3 mm or more and 15 mm or less, and preferably 5 mm or more and 10 mm or less. The pitch P _L of the light emitting elements 2 is, for example, 4 mm or more and 20 mm or less, preferably 5 mm or more and 15 mm or less, and more preferably 6 mm or more and 10 mm or less.

The distance D1 between adjacent light emitting elements 2 is, for example, 4 mm or more and 20 mm or less, and preferably 6 mm or more and 10 mm or less. The channel width W4 (or average channel width Wx) is, for example, 5 mm or more and 19 mm or less, and preferably 6 mm or more and 10 mm or less. The thickness T2 of the strips (36, 37) is, for example, 0.5 mm or more and 3 mm or less, and more preferably 0.8 mm or more and 1.5 mm or less.

As shown in FIG. 5, in the cross section of the channel (35a, 35b) of the main body 30a of the cooling plate in the light source device 100, the corner 39 of the channel (35a, 35b) is rounded. This allows the refrigerant to flow smoothly within the flow paths (35a, 35b).

FIG. 6 is a diagram of the light source device 100 viewed from the +Z side in the normal direction of the main surface of the substrate 10. The flow paths inside the cooling plate 30 are shown with broken lines. The flow path 35 cannot necessarily be arranged over the entire area of the cooling plate 30. In this embodiment, as shown in FIG. 6, there are regions at the four corners of the cooling plate 30 where the flow paths 35 are not arranged. Note that the region where the flow path 35 is not arranged may exist other than the four corners of the cooling plate 30.

Shifting the viewpoint to the substrate 10 in FIG. 6, the power supply section 5 on the substrate 10 is located on the main surface of the cooling plate 30 in a manner that mainly overlaps an area where there is no flow path 35 (the four corners of the cooling plate 30). in position. Since the amount of heat generated by the power supply section 5 is negligible compared to the amount of heat generated by the light emitting element 2, it is possible to arrange the light emitting element 2, which has a large amount of heat, so as to overlap with a certain area of the flow path 35. , the power supply unit 5 is arranged so as to overlap an area where there is no flow path 35. In other words, by arranging the flow path 35 to give priority to cooling the light emitting element 2, effective cooling can be performed.

[Arrangement of inlet and outlet]
As shown in FIG. 3, in the light source device 100 of this embodiment, the inlet 31 is located at a position across the spiral flow path from the outlet 32. In other words, the inlet 31 is located at a distance from the outlet 32. The effect of separating the inlet 31 from the outlet 32 will be explained with reference to FIG. 7.

FIG. 7 shows a main body 40a of the cooling plate in which the inlet 31 is not separated from the outlet 32. Since the inlet 31 is close to the outlet 32, heat transfer Tm occurs between the refrigerants flowing through the respective flow paths (35a, 35b) within the region R1. In FIG. 7, the direction of heat transfer is indicated by thick arrows, and "Tm" is attached to one of the thick arrows.

Specifically, the refrigerant flowing through the first channel 35a within the region R1 including the inlet 31 and the outlet 32 receives heat from the refrigerant flowing through the second channel 35b within the region R1. This increases the temperature of the refrigerant in the first flow path 35a. The refrigerant flowing through the second flow path 35b within the region R1 gives heat to the refrigerant flowing through the first flow path 35a within the region R1. As a result, the temperature of the refrigerant in the second flow path 35b decreases.

However, there is no light emitting element 2 near the second flow path 35b in the region R1. Therefore, there is no need to lower the temperature of the refrigerant in the second flow path 35b within the region R1. On the contrary, since the temperature of the refrigerant in the first flow path 35a increases within the region R1, the cooling ability of the refrigerant is reduced.

On the other hand, as shown in FIG. 3, when the inlet 31 is located apart from the outlet 32, the refrigerant flowing near the inlet 31 does not receive heat from the refrigerant flowing near the outlet 32. The first flow path 35a and the second flow path 35b can be placed adjacent to each other in a region where uniform cooling is desired. As a result, the coolant flowing through the first flow path 35a is prevented from absorbing heat that does not contribute to a decrease in the temperature of the light emitting element 2, and a decrease in cooling capacity can be suppressed.

<Second embodiment>
A light source device according to a second embodiment will be described. The following description focuses on the differences from the light source device of the first embodiment. Items not described below have the same characteristics as the light source device of the first embodiment. Similarly, in the third embodiment and subsequent embodiments, descriptions of features similar to those of the previously described light source devices will be omitted.

FIG. 8 is a diagram showing the main body 50a of the cooling plate in the light source device of the second embodiment. In the main body 50a, although the inlet 31 is not separated from the outlet 32 as in FIG. 7, a heat insulating portion 51 is provided between the inlet 31 and the outlet 32. The heat insulating part 51 is made of a material having a lower thermal conductivity than the material of the main body 50a other than the heat insulating part 51. The presence of the heat insulating portion 51 prevents heat transfer from the refrigerant in the second flow path 35b near the outlet 32 to the refrigerant in the first flow path 35a near the inlet 31. This prevents the coolant flowing through the first flow path 35a from absorbing heat that does not contribute to a decrease in the temperature of the light emitting element 2, thereby suppressing a decrease in cooling capacity.

<Third embodiment>
FIG. 9 is a cross-sectional view of the light source device of the third embodiment. In the cross section of the channel (35a, 35b) of the main body 30a of the cooling plate in the light source device 300, the corner 39 of the channel (35a, 35b) is not rounded but angular. The distance T2 between adjacent flow channels becomes uniform in the thickness direction (Z direction) of the cooling plate, and the transfer of heat between the adjacent flow channels can be promoted.

<Fourth embodiment>
FIG. 10 is a cross-sectional view of the light source device of the fourth embodiment. In the cross section of the flow path (35a, 35b) of the main body 30a of the cooling plate in the light source device 400, the flow path (35a, 35b) is approximately circular. Since the cross section of the flow path (35a, 35b) has no corners, the flow of the refrigerant in the flow path (35a, 35b) is less likely to become turbulent.

The first to fourth embodiments and modifications of each embodiment have been described above. However, the present invention is not limited to the above-described embodiments and modifications of the embodiments, and the above-described embodiments or modifications may be combined without departing from the spirit of the present invention. can. Furthermore, various changes or improvements may be made to each embodiment and modification without departing from the spirit of the present invention.

2: Light emitting element 5: Power supply section 10: Substrate 30: Cooling plates 30a, 40a, 50a: Main body 30b (of the cooling plate): Lid body 30d (of the cooling plate): Base 31 (of the cooling plate): Inflow port 32 : Outlet port 35 : Channel 35a : First channel 35b : Second channel 36 : First strip 36e : End 37 (of the first strip) : Second strip 37e : End 39 (of the second strip): Corner part 41 of the channel in the channel cross section: Supply pipe 42: Discharge pipe 51: Heat insulating section 100, 300, 400: Light source device C1: Connection area P1 (of the first channel and second channel): Center point

Claims (11)

A substrate having a plurality of light emitting elements arranged on one main surface, and a cooling plate that is joined to the other main surface of the substrate and includes a spiral flow path through which a coolant flows,
The cooling plate is
the refrigerant inlet;
an outlet for the refrigerant;
a first flow path connected to the inlet and through which the refrigerant flows from outside to inside of the cooling plate;
a second flow path connected to the first flow path and the outlet, through which the refrigerant that has passed through the first flow path flows from the inside to the outside of the cooling plate;
The light source device, wherein the first flow path and the second flow path are alternately arranged from outside to inside of the cooling plate. The first flow path and the second flow path are
partitioned by a first strip located on the left side of the first flow path and the second flow path in the direction in which the refrigerant travels; and a second strip located on the right side of the first flow path and the second flow path in the direction of travel of the refrigerant. The light source device according to claim 1, characterized in that: In a connection region where the first channel connects to the second channel, the first strip and the second strip each have an end,
The light source device according to claim 2, wherein at least one of the ends has a rounded shape when viewed from the normal direction of the main surface of the cooling plate. 4. The light source device according to claim 1, wherein the spiral channel has a channel width larger than a channel thickness. Claim: wherein formula (1) is satisfied, where t is the sum of the thickness of the substrate and the thickness of the base of the cooling plate, Pw is the pitch of the flow path, and L1 is the dimension of the light emitting element. 4. The light source device according to any one of 1 to 3.
The light source device according to any one of claims 1 to 3, wherein a pitch Pw of the flow paths is less than or equal to a pitch P _L of the light emitting elements. According to any one of claims 1 to 3, in the spiral channel portion, the channel width of the first channel is substantially the same as the channel width of the second channel. light source device. The light source device according to any one of claims 1 to 3, wherein the inlet is located apart from the outlet so that heat conduction from the outlet is suppressed. . The light source according to any one of claims 1 to 3, wherein the power supply unit that supplies power to the light emitting element overlaps an area without the flow path on the main surface of the cooling plate. Device. The light source device according to claim 1, wherein the cooling plate includes a main body and a lid, and the main body is made of a solid metal plate. The light source device according to any one of claims 1 to 3, wherein the material of the strip defining the flow path is the same as the material of the base joined to the other surface of the substrate.