Light source device

Abstract

To provide a light source device which can enhance the homogeneity of optical output between a plurality of light emitting elements.SOLUTION: A light source device comprises: a baseboard with a plurality of light emitting elements arranged on one principal surface; and a cooling plate joined to the other principal surface of the baseboard and including a spiral flow passage in which a refrigerant circulates. The cooling plate includes: a refrigerant flow-in port; a refrigerant flow-out port; a first flow passage which is connected to the flow-in port and in which the refrigerant flows from the outside of the cooling plate toward the inside; and a second flow passage which is connected to the first flow passage and the flow-out port, and in which the refrigerant that has passed through the first flow passage flows from the inside of the cooling plate toward the outside. The first flow passage and the second flow passage are alternately arranged from the outside of the cooling plate toward the inside.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a light source device.

Background Art

[0002] Light source devices using a plurality of light-emitting elements such as LEDs and LDs are used in various fields. The light-emitting elements generate heat while emitting light. When the temperature of the light-emitting elements rises due to heat generation, the light-emitting efficiency of the light-emitting elements 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).

[0003] By shifting the perspective to semiconductor elements that are not light-emitting elements, there are various types of cooling mechanisms for semiconductor elements. A method of cooling a power semiconductor element by laminating it in multiple layers so as to be sandwiched between cooling plates having a flow path through which a refrigerant flows is known (see Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Light source devices using a plurality of light-emitting elements such as LEDs and LDs are also used in drying printing ink, bonding electronic components with an ultraviolet curable resin, or exposing a photosensitive resist. In these technical fields, uniform illumination on the irradiated surface of the light source device is required from the market. To achieve uniform illumination, it is necessary to equalize the light output between the plurality of light-emitting elements.

[0006] Therefore, the objective is to provide a light source device that can improve the uniformity of light output between multiple light-emitting elements. [Means for solving the problem]

[0007] The inventors focused on the fact that the temperature of a light-emitting element affects its light output, and investigated ways to improve the uniformity of light output by equalizing the temperature between light-emitting elements. As a result of the inventors' diligent research, they conceived the idea of ​​optimizing the design of a cooling plate that contacts a substrate on which multiple light-emitting elements are arranged, in order to equalize the temperature between light-emitting elements, and devised the following light source device.

[0008] The light source device of the present invention comprises a substrate on which a plurality of light-emitting elements are arranged on one main surface, and a cooling plate bonded to the other main surface of the substrate and containing a spiral-shaped channel through which a refrigerant flows. The cooling plate is The refrigerant inlet and, The outlet of the refrigerant, A first flow path connected to the inlet, through which the refrigerant flows from outside to inside the cooling plate, The first flow path and the outlet are connected to a second flow path 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 arranged alternately from the outside to the inside of the cooling plate.

[0009] First, let's explain the terminology used in this specification. In this specification, "main surface" refers to a surface of a plate-like object that has a much larger area than the other surfaces. In this specification, a plate-like object, such as a "substrate" or a "cooling plate," each has two opposing main surfaces.

[0010] In this specification, when the term "channel" is used, it encompasses both the "first channel" and the "second channel."

[0011] In addition to direct bonding between the substrate and the cooling plate without any intermediaries, 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 part of the cooling plate.

[0012] The aforementioned light source device has a cooling plate bonded to the main surface of the substrate on which the multiple light-emitting elements are arranged, on the side opposite to the main surface where the light-emitting elements are arranged. This allows for the extraction of light from multiple light-emitting elements while simultaneously cooling the multiple light-emitting elements. Furthermore, because the distance between each light-emitting element and the cooling plate is uniform, a more uniform cooling effect can be obtained for each light-emitting element.

[0013] However, a more detailed analysis of the cooling plate reveals that, in the case of a cooling plate containing a flow path for refrigerant, the cooling effect of the cooling plate varies locally depending on the arrangement of the flow path. In particular, the refrigerant near the inlet has not yet absorbed much heat, so its temperature is relatively low and its cooling effect is greater. In contrast, the refrigerant near the outlet has already absorbed a lot of heat, so its temperature is relatively high and its cooling effect is smaller. Therefore, light-emitting elements near the first flow path near the inlet are cooled more easily than light-emitting elements near the second flow path near the outlet, and this difference in cooling effect may result in a difference in the light output of the light-emitting elements.

[0014] In the aforementioned light source device, the first channel near the inlet and the second channel near the outlet are arranged alternately from the outside to the inside of the cooling plate. As a result, heat transfer occurs from the refrigerant in the second channel to the refrigerant in the first channel on the cooling plate, reducing the temperature difference between the refrigerant flowing through the first channel and the refrigerant flowing through the second channel. Consequently, the temperature of the cooling plate becomes more uniform, and the multiple light-emitting elements can be cooled more evenly.

[0015] The first channel and the second channel are, The first flow path and the second flow path may be partitioned by a first strip located on the left side in the refrigerant flow direction and a second strip located on the right side in the refrigerant flow direction of the first flow path and the second flow path. In this specification, "strip" represents a thin and elongated strip-shaped object. The first flow path and the second flow path are partitioned by two strips.

[0016] In the connection region where the first flow path is connected to the second flow path, the first strip and the second strip each have an end. When viewed from the normal direction of the main surface of the cooling plate, at least one of the ends may have a rounded shape. Thereby, the refrigerant is less likely to become a turbulent flow, and the cooling efficiency is improved.

[0017] In the spiral flow path, the flow path width may be a shape larger than the flow path thickness. When the flow path width is larger than the flow path thickness, the amount of refrigerant can be increased and the cooling efficiency can be enhanced while the thickness of the cooling plate is limited.

[0018] 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, it may satisfy the formula (1). Although details will be described later, such a dimension design of the cooling plate can suppress the influence of the difference in cooling efficiency due to the temperature difference of the refrigerant between the first flow path 35a and the second flow path 35b on the heat absorption of the light-emitting element.

Number

[0019] The pitch Pw of the flow path may be less than or equal to the pitch P of the light-emitting element. L The following may be satisfied.

[0020] 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" means 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. 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% of the channel width of the first channel, and even more preferable that it is within 3% of the channel width of the first channel.

[0021] So that heat conduction from the outlet is suppressed, the inlet may be at a position spaced apart from the outlet. It is suppressed that the refrigerant flowing through the first channel near the inlet receives heat from the refrigerant flowing through the second channel near the outlet. Thereby, it is possible to prevent the refrigerant flowing through the first channel near the inlet from absorbing heat that does not contribute to the temperature drop of the light-emitting element. As a result, effective cooling can be performed.

[0022] The power supply unit that supplies power to the light-emitting element may overlap with the region without the channel on the main surface of the cooling plate. The cooling plate has a region with a channel and a region without a channel. By allowing the power supply unit to overlap with the region without the channel, the arrangement of the channels can be prioritized for cooling the light-emitting element. As a result, effective cooling can be performed.

[0023] The cooling plate may include a main body and a lid body, and the main body may be composed of a solid metal plate. Here, the main body may be joined to the substrate on which the light-emitting element is disposed, or the lid body may be joined to the substrate on which the light-emitting element is disposed. The material of the strip that partitions the channel may be the same as the material of the base joined to the other surface of the substrate. As an example, the strip and the base that constitute the main body of the cooling plate are formed by cutting out a single metal plate. Thereby, there is no joint portion of the material in the main body, and the strength and thermal conductivity of the main body are improved.

Advantages of the Invention

[0024] A light source device capable of enhancing the uniformity of light output between a plurality of light-emitting elements can be provided. [Brief explanation of the drawing]

[0025] [Figure 1] This is a perspective view of the light source device of the first embodiment. [Figure 2] This is a perspective view of the light source device of the first embodiment. [Figure 3] This is a view of the cooling plate body from the -Z side of the cooling plate. [Figure 4A] Figure 3 is an enlarged view of the connection area between the first and second flow channels. [Figure 4B] This diagram shows a reference configuration of the connection area between the first and second flow channels. [Figure 5] This is a cross-sectional view of the light source device of the first embodiment. [Figure 6] This diagram shows the light source device viewed from the +Z side in the direction normal to the main surface of the substrate. [Figure 7] This diagram shows the body of a cooling plate with its inlet close to its outlet. [Figure 8] This figure shows the body of the cooling plate according to the second embodiment. [Figure 9] This is a cross-sectional view of the light source device of the third embodiment. [Figure 10] This is a cross-sectional view of the light source device according to the fourth embodiment. [Modes for carrying out the invention]

[0026] Each embodiment of the light source device will be described with reference to the drawings. It should be noted that the drawings disclosed herein are for illustrative purposes only. That is, the dimensional ratios in the drawings do not necessarily correspond to the actual dimensional ratios, and the dimensional ratios do not necessarily correspond between the drawings.

[0027] The drawings are described with reference to the XYZ coordinate system. In this specification, when directions are expressed, positive and negative directions are distinguished and indicated with a sign, such as "+X direction" and "-X direction". When directions are expressed without distinguishing between positive and negative directions, they are simply described as "X direction". In other words, in this specification, when simply described as "X direction", both "+X direction" and "-X direction" are included. The same applies to the Y direction and Z direction.

[0028] <First Embodiment> [Overview of the Light Source Device] A first embodiment of the light source device will be described with reference to Figure 1. Figure 1 is a perspective view of the light source device 100. As shown in Figure 1, the light source device 100 has 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 shown to extend along the XY plane, respectively. The thickness direction of the substrate 10 and the cooling plate 30 is shown to be the Z direction.

[0029] Multiple light-emitting elements 2 are arranged on one main surface of the substrate 10. In Figure 1, one of the multiple light-emitting elements 2 is denoted by the reference numeral "2". As will be described in detail later, the multiple light-emitting elements 2 in this embodiment are arranged to form equal pitches with respect to each other. Specifically, on the substrate 10, one light-emitting element 2 is at the center, and adjacent light-emitting elements 2 are arranged at six points around it that are equidistant from the aforementioned light-emitting element 2. The light-emitting elements 2 arranged at the six points form the vertices of a regular hexagon. As a result, each light-emitting element 2 is arranged at equal pitches on the XY plane. However, the multiple light-emitting elements 2 do not necessarily have to be arranged to form the vertices of a regular hexagon. For example, the multiple light-emitting elements 2 may be arranged to form the vertices of a square. Furthermore, the multiple light-emitting elements 2 do not have to be arranged at equal pitches. For example, the multiple light-emitting elements 2 may be arranged to form the vertices of a polygon that is not a regular polygon (a hexagon that is not a regular hexagon, or a rectangle, etc.).

[0030] A cooling plate 30 is joined to the other main surface of the substrate 10. The cooling plate 30 includes a channel for circulating refrigerant inside. Details of the channel will be described later. The refrigerant is supplied from the supply pipe 41 to the cooling plate 30, passes through the channel 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 has a main body 30a and a cover 30b joined to the main body 30a. Details will be described later, but a channel is formed inside when the main body 30a and the cover 30b are joined.

[0031] The light emitted 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 exhibits a square shape. However, the shape of the light-emitting element 2 is not particularly limited, and it may exhibit a rectangular, circular, or elliptical shape, for example. The light-emitting element 2 is not limited to a chip-type light-emitting element in which multiple light-emitting elements are mounted on a substrate, as shown in Figure 1. For example, it may be a single light-emitting element or a package-type light-emitting element in which multiple light-emitting elements are packaged together. The dimensions L1 of the light-emitting element 2 are not particularly limited, but in the case of a chip type, for example, it may be 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 dimensions L1 of the light-emitting element 2 are expressed as the length of the longest side or the maximum diameter of the light-emitting element 2.

[0032] The light-emitting element 2 is preferably a solid-state light-emitting element. 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, it may emit visible light, ultraviolet light, or infrared light.

[0033] Regardless of whether the light-emitting element 2 is of chip type or 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 a substrate bonded to a single cooling plate is often 20 or more, preferably 50 or more, and more preferably 100 or more. The number of light-emitting elements 2 arranged on the substrate 10 is often 5000 or less, preferably 1000 or less, and more preferably 500 or less.

[0034] The dimensions of the substrate 10 bonded to a single cooling plate are preferably 50 mm or more in each X / Y direction, and more preferably 80 mm or more. The dimensions of the substrate 10 are preferably 500 mm or less in each X / Y direction, and more preferably 200 mm or less.

[0035] The light source device 100 has a power supply unit 5 for supplying power to each of the light-emitting elements 2. In this embodiment, the power supply unit 5 is a power supply connector configured to be connectable to an external power source. The light source device 100 has four power supply units 5 so that power can be supplied to the multiple light-emitting elements 2 that make up the light source device 100 in a shared manner.

[0036] Figure 2 is a perspective view of the light source device 100. However, in Figure 2, the cover 30b is removed so that the flow path 35 can be seen. The 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.

[0037] Figure 3 is a view of the main body 30a 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. Hatching is applied to the areas where water does not flow in order to make the inlet 31, outlet 32, and flow path 35 easier to identify. Similar hatching is also applied to Figures 4A, 4B, 7, and 8, which will be described later.

[0038] [Spiral channel] The flow path 35 will be described with reference to Figure 3. 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, excluding the vicinity of the inlet 31 and the vicinity of the outlet 32, exhibits a vortex shape. The first flow path 35a includes a portion in which the refrigerant flows from the outside to the inside of the cooling plate 30, and the second flow path 35b includes a portion in which the refrigerant flows from the inside to the outside of the cooling plate 30. 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 vortex.

[0039] The first channel 35a and the second channel 35b are arranged alternately from outside the cooling plate 30 toward the center point P1. The reason for this is explained below. The refrigerant flowing through channel 35 absorbs heat and becomes hotter as it moves downstream. Therefore, the refrigerant flowing through the second channel 35b tends to become hotter than the refrigerant flowing through the first channel 35a. However, when the first channel 35a and the second channel 35b are arranged alternately, heat transfer occurs from the refrigerant in the second channel 35b to the refrigerant in the first channel 35a, reducing the temperature difference between the refrigerant flowing through the first channel 35a and the refrigerant flowing through the second channel 35b. When the temperature difference between the refrigerants flowing through the two channels (35a, 35b) is reduced, the substrate 10, and consequently the multiple light-emitting elements 2, that are bonded to the cooling plate 30 can be cooled evenly.

[0040] As shown in Figure 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 exhibits a generally circular (or generally elliptical) spiral shape with no corners overall. Because the spiral flow path 35 has no corners overall, the refrigerant can flow smoothly. However, the spiral flow path may also have a shape that includes parts with corners overall (for example, a polygon).

[0041] The first channel 35a and the second channel 35b are formed by being separated by a thin, elongated, spiral-shaped strip. As shown in Figure 3, the strip has a first strip 36 located on the left side in the direction of travel of the first channel 35a and the second channel 35b (to the left with respect to the direction of refrigerant flow), and a second strip 37 located on the right side in the direction of travel of the first channel 35a and the second channel 35b (to the right with respect to the direction of refrigerant flow).

[0042] As shown in Figure 3, the first strip 36 and the second strip 37 each protrude from a part of the main body 30a and are wound around a central point P1. The first strip 36 and the second strip 37 demarcate the first flow path 35a and the second flow path 35b. The flow path 35 may be demarcated by three or more strips. For example, the strips may be arranged to provide two sets of inlet 31 and outlet 32 ​​combinations.

[0043] Figure 4A is an enlarged view of the connection region C1 in Figure 3, where the first channel 35a connects to the second channel 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 region C1. The center point P1 of the vortex of the channels (35a, 35b) is located at the midpoint of the line segment LS connecting the end 36e and the end 37e.

[0044] Both ends (36e, 37e) have a rounded shape and no corners. When the ends have a corner shape (Figure 4B), the refrigerant flow changes direction abruptly and is prone to turbulence. In contrast, with the rounded ends (36e, 37e) shown in Figure 4A, the refrigerant flow changes direction smoothly and is less prone to turbulence.

[0045] The channel width Wn is expressed as the distance between the first strip 36 and the second strip 37 on a line LO perpendicular to the median line LI, which is equidistant from the first strip 36 and the second strip 37, which are positioned opposite each other to form the channel 35. A small deviation in the channel width is preferable. If the deviation in the channel width is large, the flow velocity increases in the narrower parts of the channel and decreases in the wider parts, making turbulence more likely. In contrast, if the deviation in the channel width is small, the flow velocity becomes constant and turbulence is less likely.

[0046] As shown in Figure 4A, W1, W2, and W3 are all channel widths. A small deviation in the channel widths (W1, W2, W3) (the difference between the channel width at each location and the average channel width Wx) is preferable. The rounding of the ends (36e, 37e) reduces the deviation in channel width. The average channel width Wx is determined by the average value of channel widths measured at multiple locations (for example, 5 locations) in the channel of the spiral section.

[0047] Figure 4B shows a reference configuration of the flow path shape in the connection region C1. Unlike in Figure 4A, in Figure 4B, 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 flow path width changes with respect to the direction of refrigerant flow. In other words, the deviation of the flow path width is larger compared to the case in Figure 4A. Therefore, in the connection region C1 shown in Figure 4B, the refrigerant is more likely to become turbulent than in Figure 4A.

[0048] It is preferable that the channel width be constant throughout the entire first channel 35a and second channel 35b, not just in the connection region C1. It is preferable that the channel width of the first channel 35a is approximately the same as the channel width of the second channel 35b. In the spiral channel portion, the deviation of the channel width is preferably within 5 mm, more preferably within 3 mm, and even more preferably within 1 mm.

[0049] Either the end 37e of the second strip 37 or the end 36e of the first strip 36 may have a rounded shape.

[0050] Figure 5 is a cross-sectional view showing an enlarged portion of the light source device 100. Figure 5 is a cross-sectional view of a plane perpendicular to the main surface of the cooling plate 30 and perpendicular to the direction of flow of the refrigerant in the flow path 35.

[0051] As shown in Figure 5, the main body 30a of the cooling plate 30 includes strips (36, 37) and bases 30d of the strips (36, 37) in the thickness direction. In this embodiment, the main body 30a is made from a solid metal plate. That is, the strips (36, 37) and bases 30d of the strips (36, 37) are formed by machining a single metal plate. Therefore, since the strips (36, 37) and bases 30d are made of the same material, there is no difference in thermal expansion between them, and they are not subjected to thermal distortion due to differences in thermal expansion. Furthermore, since there is no joint between the strips (36, 37) and bases 30d, there is no reduction in strength at the joint, and heat from the substrate 10 is easily conducted to the cooling plate 30.

[0052] The main body 30a of the cooling plate 30 may be manufactured by other methods. The main body 30a may be joined to the base 30d by welding or adhesive, for example, by welding the first strip 36 and the second strip 37. The main body 30a may be constructed by forming grooves in the base 30d into which the first strip 36 and the second strip 37 are fitted, and then fitting the first strip 36 and the second strip 37 into these grooves. The first strip 36, the second strip 37, and the base 30d may be formed by 3D printing.

[0053] The method for forming the main body 30a described above may also be applied to the cover 30b of the cooling plate 30. In Figure 5, the main body 30a having strips (36, 37) is bonded to the substrate 10, but this is not the only option. Instead of the main body 30a, a cover 30b without strips (36, 37) may be bonded to the substrate 10.

[0054] The channel thickness H2 is smaller than the channel width W4. In other words, by relatively narrowing the spacing between each channel, it is easier to maintain heat transport between channels. For example, as shown in Figure 5, by making the channel cross-section flat, it is possible to increase the channel width to promote heat transport while relatively reducing the channel thickness H2, thereby making it easier to maintain heat transport between channels. Furthermore, any shape, such as a circle, can be used for the cross-sectional shape forming the channel 35. However, from the viewpoint of promoting heat transport between 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. Also, it is desirable that each channel formed by the first strip 36 and the second strip 37 be formed at equal intervals.

[0055] When the sum 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 dimensions of the light-emitting element 2 are L1, the light source device 100 may satisfy equation (1).

[0056]

number

[0057] The heat from each light-emitting element 2 diffuses in the -Z direction and simultaneously in the ±Y direction. The larger the total thickness t, the greater the heat diffusion in the ±Y direction. When equation (1) is satisfied, the diffusion of heat in the ±Y direction expands to more than the pitch Pw of the flow path 35. As a result, the heat generated in each light-emitting element 2 reaches the two adjacent flow paths (first flow path 35a and second flow path 35b) through diffusion in the ±Y direction and is absorbed by both the refrigerant flowing in the first flow path 35a and the refrigerant flowing in the second flow path 35b. This dimensional design makes it possible to suppress the influence of the difference in cooling efficiency due to the temperature difference of the refrigerant 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 should be, for example, 1.8 mm or more.

[0058] The light source device 100 may also satisfy equation (2).

number

[0059] To minimize the impact of the difference in cooling efficiency due to the temperature difference of the refrigerant in the first channel 35a and the second channel 35b on the heat absorption of the light-emitting element 2, the total thickness t should be such that the heat from each light-emitting element 2 diffuses throughout the two adjacent channels (first channel 35a and second channel 35b). Furthermore, since the cost increases and space is occupied as the total thickness t increases, cooling can be effectively achieved by designing the light source device 100 so that the total thickness satisfies equation (2). The total thickness t should, for example, be 4.7 mm or less.

[0060] The pitch Pw of the flow path 35 is equal to the pitch P of the light-emitting element 2. L (See Figure 5) It may also be less than or equal to the following. The pitch Pw of the flow path 35 is, for example, 3 mm or more and 15 mm or less, and preferably 5 mm or more and 10 mm or less. Pitch P of the light-emitting element 2 L For example, it is 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.

[0061] 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 flow path width W4 (or average flow path 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 strip (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.

[0062] As shown in Figure 5, in the cross-section of the flow channels (35a, 35b) of the main body 30a of the cooling plate in the light source device 100, the corners 39 of the flow channels (35a, 35b) are rounded. This allows the refrigerant to flow smoothly through the flow channels (35a, 35b).

[0063] Figure 6 shows the light source device 100 viewed from the +Z side in the direction normal to the main surface of the substrate 10. The flow channels inside the cooling plate 30 are shown by dashed lines. The flow channels 35 are not necessarily arranged throughout the entire area of ​​the cooling plate 30. In this embodiment, as shown in Figure 6, there are areas at the four corners of the cooling plate 30 where the flow channels 35 are not arranged. Note that areas where the flow channels 35 are not arranged may exist at locations other than the four corners of the cooling plate 30.

[0064] Shifting our focus to the substrate 10 in Figure 6, the power supply unit 5 on the substrate 10 is positioned on the main surface of the cooling plate 30 so as to overlap mainly with areas without flow channels 35 (the four corners of the cooling plate 30). Since the heat generated by the power supply unit 5 is negligible compared to the heat generated by the light-emitting element 2, the light-emitting element 2, which generates a large amount of heat, is positioned so as to overlap with the area with flow channels 35 as possible, while the power supply unit 5 is positioned so as to overlap with the area without flow channels 35. In other words, by positioning the flow channels 35 to prioritize the cooling of the light-emitting element 2, effective cooling can be achieved.

[0065] [Placement of inlet and outlet] As shown in Figure 3, in the light source device 100 of this embodiment, the inlet 31 is located across a spiral-shaped 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 Figure 7.

[0066] Figure 7 shows the main body 40a of the cooling plate where the inlet 31 is not spaced apart from the outlet 32. Because the inlet 31 is close to the outlet 32, heat transfer Tm occurs between the refrigerants flowing through the respective channels (35a, 35b) within region R1. In Figure 7, the direction of heat transfer is indicated by thick arrows, and one of the thick arrows is labeled "Tm".

[0067] Specifically, the refrigerant flowing through the first channel 35a within region R1, which includes the inlet 31 and outlet 32, receives heat from the refrigerant flowing through the second channel 35b within region R1. This causes the temperature of the refrigerant in the first channel 35a to rise. The refrigerant flowing through the second channel 35b within region R1 transfers heat to the refrigerant flowing through the first channel 35a within region R1. This causes the temperature of the refrigerant in the second channel 35b to fall.

[0068] However, there is no light-emitting element 2 near the second channel 35b within region R1. Therefore, there is no need to lower the temperature of the refrigerant in the second channel 35b within region R1. On the contrary, the temperature of the refrigerant in the first channel 35a rises within region R1, which reduces the cooling capacity of the refrigerant.

[0069] In contrast, as shown in Figure 3, when the inlet 31 is located at a distance from the outlet 32, the refrigerant flowing near the inlet 31 does not receive heat from the refrigerant flowing near the outlet 32. This allows the first flow path 35a and the second flow path 35b to be adjacent to each other in the region where uniform cooling is desired. As a result, the refrigerant flowing through the first flow path 35a is prevented from absorbing heat that does not contribute to the temperature reduction of the light-emitting element 2, thereby suppressing a decrease in cooling capacity.

[0070] <Second Embodiment> The light source device of the second embodiment will be described. The explanation will focus on the differences from the light source device of the first embodiment. Matters not described below have the same characteristics as the light source device of the first embodiment. Similarly, for the third embodiment and subsequent embodiments, matters that have the same characteristics as the previously described light source devices will be omitted from the explanation.

[0071] Figure 8 shows the main body 50a of the cooling plate in the light source device of the second embodiment. In the main body 50a, the inlet 31 is not separated from the outlet 32, as in Figure 7, but there is an insulating section 51 between the inlet 31 and the outlet 32. The insulating section 51 is made of a material with lower thermal conductivity than the material of the main body 50a other than the insulating section 51. Because of the presence of the insulating section 51, heat transfer from the refrigerant in the second channel 35b near the outlet 32 ​​to the refrigerant in the first channel 35a near the inlet 31 is hindered. As a result, the refrigerant flowing through the first channel 35a is prevented from absorbing heat that does not contribute to the temperature reduction of the light-emitting element 2, and the decrease in cooling capacity is suppressed.

[0072] <Third Embodiment> Figure 9 is a cross-sectional view of the light source device of the third embodiment. In the cross-section of the flow channels (35a, 35b) of the main body 30a of the cooling plate in the light source device 300, the corners 39 of the flow channels (35a, 35b) are not rounded but are angular. The distance T2 between adjacent flow channels is uniform in the thickness direction (Z direction) of the cooling plate, which promotes heat transfer between adjacent flow channels.

[0073] <Fourth Embodiment> Figure 10 is a cross-sectional view of the light source device of the fourth embodiment. In the cross-section of the flow channels (35a, 35b) of the main body 30a of the cooling plate in the light source device 400, the flow channels (35a, 35b) are approximately circular. Because the cross-section of the flow channels (35a, 35b) has no corners, the flow of refrigerant within the flow channels (35a, 35b) is less likely to become turbulent.

[0074] The first to fourth embodiments and variations thereof have been described above. However, the present invention is not limited in any way to the embodiments and variations thereof described above, and the embodiments or variations described above can be combined without departing from the spirit of the present invention. Furthermore, various changes or improvements can be made to each embodiment and variation without departing from the spirit of the present invention. [Explanation of Symbols]

[0075] 2: Light-emitting element 5: Power supply section 10: Circuit board 30: Cooling plate 30a, 40a, 50a: (Cooling plate) main body 30b: Cover (of the cooling plate) 30d: Base (of the cooling plate) 31:Inlet 32: Outlet 35: Flow path 35a: First channel 35b: Second flow path 36: First Strip 36e: (The end of the first strip) 37: Second Strip 37e: (The end of the second strip) 39: Corner of the channel in the channel cross-section 41: Supply pipe 42: Discharge pipe 51: Insulation section 100,300,400: Light source device C1: Connection area (between the first and second channels) P1: Center point

Claims

1. A substrate on which multiple light-emitting elements are arranged on one main surface, and a bonded element on the other main surface of the substrate, It comprises a cooling plate that includes a swirling channel through which a refrigerant flows, The cooling plate is The refrigerant inlet and, The outlet of the refrigerant, A first flow path connected to the inlet, through which the refrigerant flows from outside to inside the cooling plate, The first flow path and the outlet are connected to a second flow path 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 channel and the second channel are arranged alternately from the outside to the inside of the cooling plate. The first channel and the second channel are separated by a first strip located on the left side in the direction of travel of the refrigerant in the first channel and the second channel, and a second strip located on the right side in the direction of travel of the refrigerant in the first channel and the second channel. A light source device characterized in that, in the connection region where the first channel connects to the second channel, the first strip and the second strip each have an end.

2. The light source device according to claim 1, characterized in that, when viewed from the direction normal to the main surface of the cooling plate, at least one of the ends has a rounded shape.

3. The light source device according to claim 1 or 2, characterized in that the width of the channel is greater than the thickness of the channel in the spiral channel.

4. The light source device according to claim 1 or 2, characterized in that 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 dimensions of the light-emitting element are L1, the device satisfies equation (1). [Math 1]

5. The pitch Pw of the aforementioned flow path is the pitch P of the aforementioned light-emitting element. Ｌ The light source device according to claim 1 or 2, characterized in that it is as follows:

6. The light source device according to claim 1 or 2, characterized in that, in the spiral-shaped flow channel portion, the flow channel width of the first flow channel is substantially the same as the flow channel width of the second flow channel.

7. The light source device according to claim 1 or 2, characterized in that the inlet is located at a distance from the outlet so as to suppress heat conduction from the outlet.

8. The light source device according to claim 1 or 2, characterized in that the power supply unit that supplies power to the light-emitting element overlaps with the region without the flow path on the main surface of the cooling plate.

9. The light source device according to claim 1 or 2, characterized in that the cooling plate includes a main body and a lid, and the main body is made of a solid metal plate.

10. The light source device according to claim 1 or 2, characterized in that the material of the strip that demarcates the flow path is the same as the material of the base that is bonded to the other surface of the substrate.

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