Light source unit and light irradiation device

Abstract

To facilitate appropriate cooling of a light source by an air-cooled heat sink even when a light source unit is elongated or when a light source generating a large amount of heat is employed.SOLUTION: In the light source unit 10, the heat sink 31 includes the plurality of fins 33 arranged at the predetermined pitch in the intersecting direction intersecting the extending direction of the cooling tube 21, the cooling tube 21 has the shape in which the opening area decreases from the upstream side toward the downstream side of the cooling air, and the plurality of fins 33 are formed such that the height h increases stepwise from the upstream side toward the downstream side of the cooling air and the pitch p increases stepwise from the upstream side toward the downstream side of the cooling air.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a light source unit and a light irradiation device. [Background technology]

[0002] A light irradiation device is known that includes an air-cooled light source unit in which light sources arranged in a line are attached to a cooling pipe, a heat sink is formed on the surface of the cooling pipe facing the light source, and cooling air is supplied into the cooling pipe by a blower fan (for example, Patent Document 1). For this type of heat sink, a configuration has been proposed in which the surface area of ​​the fins is reduced stepwise or continuously from the exhaust side to the intake side by arranging fins of different depths in parallel or by cutting out a portion of the intake side of the fin (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-155359 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-235387 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when the light source unit is made longer or when a light source that generates a lot of heat (such as a high-output LED) is used, it is generally considered to use a water-cooled system, which has a higher cooling capacity than an air-cooled system. However, water-cooled systems require a water-cooling circuit, which requires measures to prevent water leaks and condensation, as well as maintenance. On the other hand, if air-cooled systems are designed to improve cooling performance by increasing the size of the blower fan or the fin area, it becomes difficult to secure the space for the blower fan, and there is also the risk of large temperature differences between the light sources due to variations in cooling performance. Therefore, an object of the present disclosure is to make it easier to properly cool a light source with an air-cooled heat sink even when the light source unit is elongated or a light source that generates a large amount of heat is used. [Means for solving the problem]

[0005] In order to achieve the above object, an air-cooled light source unit is provided in which a linearly arranged light source is attached to a cooling pipe, a heat sink is formed on the surface of the cooling pipe facing the light source, and cooling air is supplied into the cooling pipe by a blower fan, the heat sink has a plurality of fins arranged at a predetermined pitch in a direction intersecting the extension direction of the cooling pipe, the cooling pipe has a shape in which the opening area decreases from the upstream side to the downstream side of the cooling air, the height of the plurality of fins increases stepwise from the upstream side to the downstream side of the cooling air, and the pitch increases stepwise from the upstream side to the downstream side of the cooling air. The present invention also provides a light irradiation device that includes the light source unit and irradiates an object with light from the light source unit. [Effects of the Invention]

[0006] According to the present invention, even when the light source unit is elongated or a light source that generates a large amount of heat is used, the light source can be easily cooled appropriately by an air-cooled heat sink. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a perspective view showing the light source unit according to the embodiment together with the blower fan. [Figure 2] FIG. [Figure 3] (A) is a view showing the light source unit from the light source side, (B) is a side cross-sectional view, and (C) is an enlarged view of a part of (B). [Figure 4] 10A and 10B are views showing each heat sink from the opposite side of the base portion. [Figure 5] FIG. 2 is a view showing the light source unit from the exhaust port side. [Figure 6]10 is a diagram showing specifications and test results of light source units of an example and a comparative example. FIG. [Figure 7] 10 is a diagram showing the temperature distribution of each LED in Comparative Examples 1 to 3 and Examples 1 and 2. FIG. [Figure 8] FIG. 10 is a temperature distribution diagram comparing the presence and absence of a taper in Comparative Example 1 and Comparative Example 2. [Figure 9] FIG. 10 is a temperature distribution diagram comparing the presence and absence of a taper in Comparative Example 3 and Example 1. [Figure 10] FIG. 10 is a side cross-sectional view showing an example of a light source unit according to another embodiment. [Figure 11] FIG. 10 is a diagram showing the specifications and test results of the light source units of Examples 3 to 6 of other embodiments. [Figure 12] FIG. 10 is a diagram showing the temperature distribution of each LED in Examples 3 to 6. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a light source unit 10 according to this embodiment together with a blower fan 11. As shown in FIG. The light source unit 10 is an air-cooled light source unit in which light sources 12 arranged in a line are attached to a cooling pipe 21, a heat sink 31 is formed on the surface of the cooling pipe 21 facing the light sources 12, and cooling air is supplied into the cooling pipe 21 by a blower fan 11. This light source unit 10 is mounted as a curing unit for curing photocurable ink in a printing device such as a sheet-fed printing press. Note that the light irradiation device that mounts the light source unit 10 is not limited to a printing device, and the object onto which the light source unit 10 irradiates light is not limited to printed matter.

[0009] Fig. 2 is a perspective view of the light source unit 10. Fig. 3(A) is a view showing the light source unit 10 from the light source 12 side, Fig. 3(B) is a side cross-sectional view, and Fig. 3(C) is an enlarged view of a portion of Fig. 3(B). The cooling pipe 21 has a long rectangular cylindrical shape and has an intake port 21a at one longitudinal end through which cooling air from the blower fan 11 flows in, and an exhaust port 21b at the other longitudinal end through which the cooling air is discharged. 3, the length of the cooling pipe 21 is indicated by the symbol L0, the width by the symbol W, and the height by the symbol H. The length L0 of the cooling pipe 21 is not particularly limited, but is, for example, not less than 500 mm and not more than 1200 mm, and is approximately 1000 mm in this embodiment. The width W and height H of the cooling pipe 21 may also be set appropriately.

[0010] A long heat sink 31 and a substrate 12k on which a plurality of LEDs constituting the linear light source 12 are mounted are attached to the cooling pipe 21. The heat sink 31 is composed of a first heat sink 31a having a length L1, a second heat sink 31b having a length L2, and a third heat sink 31c having a length L3. Note that the LED is an example of the light source 12, and known light sources such as light-emitting elements other than LEDs may also be used as appropriate. Hereinafter, the LEDs constituting the light source 12 will be referred to as "LEDs 12." Although FIG. 2 illustrates an example in which the heat sink 31 is formed of a heat sink component consisting of three heat sinks 31a to 31c, it may be formed of four or more heat sink components, or two heat sink components.

[0011] The first heat sink 31a constitutes the heat sink portion of the cooling pipe 21 closest to the intake port 21a (the most upstream side), and is integrally formed of a highly thermally conductive material, and includes a base portion 32a extending over a length L1 and a number of fins 33a provided on the back surface of the base portion 32a (corresponding to the inner surface of the cooling pipe 21). The second heat sink 31b constitutes the heat sink portion of the cooling pipe 21 located adjacent to the exhaust port 21b side of the first heat sink 31a (corresponding to the downstream side), and is integrally formed of a highly thermally conductive material, and includes a base portion 32b extending over a length L2 and a number of fins 33b provided on the back surface of the base portion 32b.

[0012] The third heat sink 31c constitutes the heat sink portion of the cooling pipe 21 that is closest to the exhaust port 21b (the most downstream side), and is disposed adjacent to the exhaust port 21b side (downstream side) of the second heat sink 31b. The third heat sink 31c integrally includes a base portion 32c extending over a length L2 and a large number of fins 33c provided on the back surface of the base portion 32c, and is made of a highly thermally conductive material.

[0013] In this embodiment, the height of each fin 33a, 33b, 33c increases stepwise from the upstream side to the downstream side of the cooling airflow. In the example of Fig. 3, the fins 33a of the first heat sink 31a are formed to the same height h1, the fins 33b of the second heat sink 31b are formed to the same height h2 that is higher than the height h1, and the fins 33c of the third heat sink 31c are formed to the same height h3 that is higher than the height h2. Since the fins 33a to 33c of each heat sink 31a to 33c are the same height, it is relatively easy to manufacture each of the heat sinks 31a to 33c. Also, since the long heat sink 31 is made up of multiple heat sinks 31a to 31c, costs can be reduced compared to when the heat sink 31 is manufactured as a single unit.

[0014] A long substrate 12k is attached to the surface (corresponding to the surface exposed to the outside) of each of the base portions 32a-32c of the heat sinks 31a-33c along the longitudinal direction of each of the heat sinks 31a-33c. An alumina substrate with high thermal conductivity is used for the substrate 12k, and the LEDs 12 are mounted at intervals along the longitudinal direction of the heat sinks 31a-33c. The longitudinal direction of the heat sinks 31a-33c coincides with the direction from upstream to downstream of the cooling airflow, and also coincides with the longitudinal direction of the cooling pipe 21 and the longitudinal direction of the light source unit 10.

[0015] The arrangement intervals of the LEDs 12 are set to a length that will provide uniform illuminance in the longitudinal direction of the cooling pipe 21, and good uniformity with little unevenness in illuminance can be obtained. Although FIG. 3 illustrates an example in which the LEDs 12 are arranged in one row, the LEDs 12 may be arranged in multiple rows, such as two rows.

[0016] Of the cooling pipe 21, the opposing surface 21m facing each heat sink 31a-31c is formed as an inclined surface extending linearly so as to approach the light source 12 as it approaches the downstream side of the cooling air. As a result, the cooling pipe 21 is formed in a shape in which the opening area decreases from the upstream side to the downstream side of the cooling pipe 21, and the flow speed of the cooling air on the downstream side can be increased. This prevents a decrease in cooling capacity on the downstream side even if there is pressure loss due to the fins 33a-33c, and makes it easier to maintain cooling performance from the upstream side to the downstream side.

[0017] The inclination angle of the opposing surface 21m may be set appropriately based on the length L0 of the cooling pipe 21, etc. In addition, by making the opposing surface 21m a curved surface extending along a predetermined arc in a side view, the opening area of ​​the cooling pipe 21 may become smaller from the upstream side to the downstream side of the cooling pipe 21. The curvature of the arc may also be set appropriately based on the length L0 of the cooling pipe 21, etc. The opposing surface 21m can also be said to be the surface opposing the surface on the light source 12 side.

[0018] Fig. 4 is a view showing each of the heat sinks 31a to 31c from the opposite side of the base portions 32a to 32c. In Fig. 4, the longitudinal direction of the cooling pipe 21 is indicated by the symbol X, and the width direction of the cooling pipe 21 is indicated by the symbol Y. Furthermore, the symbol CT in Fig. 4 is a center line connecting the centers of the LEDs 12. Fig. 5 is a view showing the light source unit 10 from the exhaust port 21b. As shown in Fig. 4, the fins 33a to 33c of each of the heat sinks 31a to 31c are arranged at intervals along the longitudinal direction X of the cooling pipe 21. The fins 33a to 33c are arranged parallel to each other at predetermined intervals (pitches p1, p2, p3 in Fig. 4) in the width direction Y of the cooling pipe 21 (which corresponds to an example of an intersecting direction intersecting the extension direction of the cooling pipe 21). The fins 33a to 33c are arranged over the entire surface of the base portions 32a to 32c. The fins 33a to 33c of each of the heat sinks 31a to 31c do not have to be arranged at intervals along the longitudinal direction X.

[0019] The pitches p1, p2, and p3 of the fins 33a to 33c increase stepwise from the upstream side to the downstream side of the cooling airflow. In the example shown in Fig. 4, the fins 33a of the first heat sink 31a are set at the same pitch p1, the fins 33b of the second heat sink 31b are set at the same pitch p2 that is wider than the pitch p1, and the fins 33c of the third heat sink 31c are set at the same pitch p3 that is wider than the pitch p2. 4, the fins 33a to 33c are arranged such that, while maintaining the pitches p1, p2, and p3, the fins 33a, 33b, and 33c are positioned on the center line LC of the LED 12. This makes it easier to dissipate heat generated at the center of each LED 12, which is expected to be advantageous for heat dissipation from the LEDs 12 arranged in a line.

[0020] 5, when all of the fins 33 are viewed from the upstream or downstream side of the cooling airflow, gaps of a predetermined size or more are formed between all of the fins 33. These gaps of a predetermined size or more are continuous from the upstream side to the downstream side of the cooling airflow, making it easier for the cooling air to flow smoothly between the fins 33 from the upstream side to the downstream side of the cooling airflow. The predetermined gap may be set to an appropriate value.

[0021] Next, examples of the present invention will be described together with comparative examples. However, the present invention is not limited to the following examples. FIG. 6 is a diagram showing the specifications and test results of the light source units 10 of the example and the comparative example. Comparative Examples 1 to 3 and Examples 1 and 2 shown in FIG. 6 share the light source unit 10 having three heat sinks 31a to 31c as shown in FIG. 3, but differ in at least one of the heights h1 to h3 and pitches p1 to p3 of the fins 33a to 33c of each heat sink 31a to 31c and the length of the base portions 32a to 32c of each heat sink 31a to 31c.

[0022] In the following description, when there is no need to distinguish between the heat sinks 31a to 31c, the fins 33a to 33c, the heights h1 to h3, the pitches p1 to p3, and the bases 32a to 32c, they will be referred to as the heat sink 31, the fins 33, the height h, the pitch p, and the base 32, respectively. Figures 10 to 12, which will be described later, are diagrams used to explain an embodiment in which the height and pitch p of the fins 33 are changed in five stages.

[0023] 6 and 11 also show test results when a test was conducted in which the LEDs 12 were turned on while cooling air was supplied into the cooling pipe 21 of each example and comparative example. The test results shown in Fig. 6 and 11 show the maximum temperature, minimum temperature, and difference between these temperatures (appropriately referred to as temperature difference) of all the LEDs 12, as well as the pressure difference between the intake port 21a and the exhaust port 21b in the cooling pipe 21. Fig. 7 is a diagram showing the temperature distribution of each LED 12 in the above test for Comparative Examples 1 to 3 and Examples 1 and 2 shown in Fig. 6. Note that the number of LEDs 12 in each Example and Comparative Example is 72, and in Fig. 7 and the figures described below, each LED 12 is numbered "LED-1," "LED-2," "LED-3," etc. in order from the upstream side.

[0024] The size A of the cooling pipe 21 shown in FIGS. 6 and 11 is 42 mm in width W and 52 mm in height H, and the air volume of the blower fan 11 is 1.6 m 3 The size B of the cooling pipe 21 shown in FIG. 11 is 42 mm in width W and 62 mm in height H, and the air volume of the blower fan 11 is 1.9 m 3 / min (cubic meters per minute). The cooling pipe 21 is "tapered" because the opposing surface 21m is inclined, that is, the opposing surface 21m is an inclined surface that approaches the light source 12 on the downstream side of the cooling air.

[0025] The height h of the heat sink 31 shown in Figures 6 and 11 is the value obtained by adding the height of the fins 33 to the base portion 32 of constant thickness, and the value C of height h is 22.0 mm, which is lower than a predetermined reference height, the value D of height h is 28.5 mm, which is the reference height, the value E of height h is 35.0 mm, which is higher than the reference height, and the value F of height h is 45.5 mm, which is higher than the reference height. The pitch p of the heat sink 31 shown in Figures 6 and 11 is the pitch in the width direction Y of the cooling pipes 21 of the fins 33, and the value A of the pitch p is 1.61 mm which is narrower than the predetermined standard pitch, the value B of the pitch p is 3.82 mm which is the standard pitch, and the value C of the pitch p is 6.03 mm which is wider than the standard pitch.

[0026] The base length value A of the heat sink 31 shown in Figures 6 and 11 is the shortest, 90 mm, the base length value B is 180 mm, which is longer than value A, the base length value C is 360 mm, which is a standard length longer than value B, and the base length value D is 450 mm, which is longer than value C. 6 and 11 indicate the maximum temperature, minimum temperature, and temperature difference corresponding to the difference between the maximum and minimum temperatures of all the LEDs 12. As described above, the pressure shown in Fig. 6 and 11 is the pressure difference between the intake port 21a and the exhaust port 21b in the cooling pipe 21. The larger this pressure difference is, the larger the pressure loss in the cooling pipe 21 is, and the smaller the pressure difference is, the smaller the pressure loss in the cooling pipe 21 is.

[0027] The temperature distribution of Comparative Example 1 is indicated by the symbol T1 in FIG. 7, the temperature distribution of Comparative Example 2 is indicated by the symbol T2 in FIG. 7, the temperature distribution of Comparative Example 3 is indicated by the symbol T3 in FIG. 7, the temperature distribution of Example 1 is indicated by the symbol T4 in FIG. 7, and the temperature distribution of Example 2 is indicated by the symbol T5 in FIG. 7.

[0028] 6, Comparative Example 1 has a configuration in which the heights h1 to h3 of the fins 33a to 33c of all heat sinks 31a to 31c are the same, the pitches p1 to p3 of the fins 33a to 33c are the same, and the cooling pipes 21 are tapered. Comparative Example 2 differs from Comparative Example 1 in that the pitches p1 to p3 of the fins 33a to 33c are gradually increased from the upstream side to the downstream side of the cooling air. Comparative Example 3 differs from Comparative Example 1 in that the heights h1 to h3 of the fins 33a to 33c are gradually increased from the upstream side to the downstream side of the cooling air. Here, by gradually increasing the pitches p1 to p3 of the fins 33a to 33c from the upstream side to the downstream side of the cooling air, it becomes easier for the cooling air to flow between the fins 33b and 33c on the downstream side, which is expected to have the effect of reducing the pressure loss of the cooling air.

[0029] 6, it can be seen that Comparative Example 2, in which the pitches p1 to p3 of the fins 33a to 33c are increased in stages, can reduce pressure loss more than Comparative Examples 1 and 3, in which the pitches p1 to p3 of the fins 33a to 33c are not increased in stages. However, Comparative Example 2 was disadvantageous in that the maximum temperature and temperature difference increased compared to Comparative Example 3, in which the pitches p1 to p3 of the fins 33a to 33c were uniform and the heights h1 to h3 of the fins 33a to 33c were increased in stages.

[0030] Furthermore, in Comparative Example 3, Example 1, and Example 2, the heights h1 to h3 of the fins 33a to 33c are increased in stages from the upstream side to the downstream side of the cooling air, which makes it easier for the cooling air flowing through the gaps between the fins 33a, 33b and the cooling pipe 21 to flow between the fins 33b and 33c on the downstream side, and is expected to have the effect of suppressing a decrease in cooling performance on the downstream side. As shown in FIG. 6, it can be seen that Comparative Example 3, in which the heights h1 to h3 of the fins 33a to 33c are gradually increased from the upstream side to the downstream side of the cooling air, can reduce the maximum temperature and temperature difference more than Comparative Examples 1 and 2, in which the heights h1 to h3 of the fins 33a to 33c are gradually increased from the upstream side to the downstream side of the cooling air. However, the pressure (pressure loss) in Comparative Example 3 is significantly higher than that in Comparative Examples 1 and 2. High pressure loss is not only disadvantageous in terms of variations in cooling performance and noise, but also leads to an increase in the size of the blower fan 11.

[0031] In contrast, in Examples 1 and 2, the heights h1 to h3 of the fins 33a to 33c are gradually increased from the upstream side to the downstream side of the cooling air, the pitches p1 to p3 of the fins 33a to 33c are gradually increased from the upstream side to the downstream side of the cooling air, and further, the cooling pipe 21 is tapered. Example 2 differs from Example 1 in that the pitch p1 of the fins 33a is increased from 1.61 mm to 3.82 mm.

[0032] 6, Examples 1 and 2 can reduce the maximum temperature and can suppress the temperature difference and pressure loss to the same extent or better than Comparative Examples 1 and 2. Moreover, Examples 1 and 2 can obtain cooling performance close to that of Comparative Example 3 while significantly reducing pressure loss compared to Comparative Example 3, and are therefore more advantageous than Comparative Example 3. Furthermore, in Example 2, in which the pitch p1 of the upstream fins 33a is increased, it is possible to reduce the maximum temperature, temperature difference, and pressure loss compared to Example 1, which is advantageous in terms of improving cooling performance and reducing pressure loss.

[0033] Next, the difference between the cooling pipe 21 having a taper and the cooling pipe 21 having no taper will be described with reference to FIGS. Fig. 8 is a temperature distribution diagram comparing the presence and absence of a taper in Comparative Example 1 and Comparative Example 2. Fig. 9 is a temperature distribution diagram comparing the presence and absence of a taper in Comparative Example 3 and Example 1. Note that Fig. 9 also shows the temperature distribution in Example 2 when the taper is present. Here, when the cooling pipe 21 is tapered, the opening area of ​​the cooling pipe 21 decreases toward the downstream side of the cooling air, making it easier to increase the flow rate on the downstream side. This is expected to promote heat dissipation on the downstream side and suppress a decrease in cooling performance on the downstream side.

[0034] 8 and 9, in all of Comparative Examples 1 to 3 and Example 1, when the cooling pipe 21 is tapered, the temperature on the downstream side (for example, the temperature after "LED-20") is lower and the temperature distribution is flatter than when the cooling pipe 21 is not tapered. When the cooling pipe 21 is tapered, it is found that, among Comparative Examples 1 to 3 and Example 1, Example 1 has the flattest temperature distribution, that is, it is easier to cool each LED 12 evenly. The temperature distribution from "LED-20" onwards corresponds to the range of the second heat sink 31b and the third heat sink 31c, and it can be seen that Example 1 with a taper evenly cools each LED 12 over a wide range from "LED-20" onwards. Furthermore, Example 2 with a taper can cool each LED 12 evenly while further reducing the maximum temperature compared to Example 1 with a taper, and is more suitable for cooling the LEDs 12 evenly with an air-cooled heat sink.

[0035] The above explanation is for the case where the height h and pitch p of the fins 33 of the heat sink 31 are changed in three stages, but in the present invention, the height h and pitch p of the fins 33 may also be changed in two stages or four or more stages. Next, another embodiment will be described in which the height h and pitch p of the fins 33 are changed in five stages.

[0036] 10 is a side cross-sectional view showing an example of a light source unit 10 according to another embodiment. Note that the same parts as those in the above embodiment are designated by the same reference numerals, and redundant explanations will be omitted. 10, the light source unit 10 according to another embodiment differs from the light source unit 10 shown in Fig. 3 in that the first heat sink 31a1 located upstream is composed of a 1a heat sink 31a1 having a length L1a, a 1b heat sink 31a2 having a length L1b, and a 1c heat sink 31a3 having a length L1c. This makes it easier to finely control the temperature of each LED 12 in the area corresponding to the 1a heat sink 31a1 (for example, around "LED-1" to "LED-23" shown in Fig. 7). In another embodiment, the height h of each of the fins 33a1 to 33a3, 33b and 33c of these five heat sinks 31a1 to 31a3, 31b and 31c increases stepwise from the upstream side to the downstream side of the cooling air, and the pitch p of each of the fins 33a1 to 33a3, 33b and 33c increases stepwise from the upstream side to the downstream side of the cooling air.

[0037] Fig. 11 is a diagram showing the specifications and test results of the light source unit 10 of Examples 3 to 6 of other embodiments. Fig. 12 is a diagram showing the temperature distribution of each LED 12 obtained by testing of Examples 3 to 6. Fig. 12 also shows the temperature distribution T5 of Example 2, which produced good results when the height h and pitch p of the fins 33 were changed in three stages. As shown in FIG. 11, in Examples 3 and 4, the cooling pipe 21 is of size A (width W is 42 mm, height H is 52 mm, and the blower fan 11 is 1.6 m 3 / min), the base length of the third heat sink 31c, which is located furthest downstream, is set to value C (360 mm) in Example 3, whereas it is set to value D (450 mm) in Example 4. Therefore, the total surface area of ​​the fins 33 is larger in Example 4. In Figure 12, the temperature distribution in Example 3 is indicated by symbol T6, and the temperature distribution in Example 4 is indicated by symbol T7.

[0038] As shown in FIG. 11, in Examples 5 and 6, the cooling pipe 21 is of size B (width W: 42 mm, height H: 62 mm, blower fan 11: 1.9 m) which is larger than size A. 3 / min), the heights of the fins 33b and 33c of the second heat sink 31b and the third heat sink 31c located downstream are made different. The height h, pitch p, and base length of the heat sink 31 in Example 5 are the same as those in Example 4. In Example 5, the height h of the second heat sink 31b is set to a value D (28.5 mm) and the height h of the third heat sink 31c is set to a value E (28.5 mm), whereas in Example 6, the height h of the second heat sink 31b is set to a value E (35.0 mm) and the height h of the third heat sink 31c is set to a value F (45.5 mm). Therefore, the total surface area of ​​the fins 33 is larger in Example 6. The temperature distribution in Example 5 is indicated by symbol T8 in FIG. 12, and the temperature distribution in Example 6 is indicated by symbol T9 in FIG. 12.

[0039] 11 and 6, Examples 3 and 4 can reduce the maximum temperature and the temperature difference and the pressure difference compared to Comparative Example 1, Comparative Example 2, Examples 1 and 2. Furthermore, Examples 3 and 4 can obtain cooling performance that is equal to or better than Comparative Example 3 while significantly reducing the pressure difference compared to Comparative Example 3. Therefore, when the cooling pipe 21 is the same size, changing the height h and pitch p of the fins 33 in five steps yields better results than changing them in three steps.

[0040] Furthermore, in Examples 5 and 6, the cooling pipes 21 are larger than those in Examples 3 and 4, and therefore the pressure loss of the cooling air can be reduced. Therefore, in Example 5, the pressure loss can be further reduced compared to Example 4, which has the same height h, pitch p, and base length of the heat sink 31. Furthermore, in Example 6, the fins 33 of the second heat sink 31b and the third heat sink 31c are higher than in Example 5, so that the decrease in cooling performance can be suppressed and the maximum temperature can be lowered compared to Example 5. As shown in FIGS. 11 and 12, the temperature distribution T6 of Example 6 has the smallest temperature difference among Examples 2 to 6, and can lower the temperature overall. Furthermore, as shown in FIG. 12, the temperature distribution T9 of Example 6 has even smaller temperature variation. Therefore, Example 6 has the best temperature distribution characteristics among Examples 2 to 6, and is suitable for uniformly cooling the LEDs 12 with an air-cooled heat sink.

[0041] As described above, in the light source unit 10 of this embodiment, the heat sink 31 includes a plurality of fins 33 arranged at a predetermined pitch p in a direction intersecting the extension direction of the cooling pipe 21, and the cooling pipe 21 has a shape in which the opening area decreases from the upstream side to the downstream side of the cooling air. Furthermore, the height h of the plurality of fins 33 increases stepwise from the upstream side to the downstream side of the cooling air, and the pitch p increases stepwise from the upstream side to the downstream side of the cooling air.

[0042] With this configuration, the height of the multiple fins 33 gradually increases toward the downstream side. This allows the cooling air flowing through the gaps between the upstream fins 33 and the cooling pipe 21 to more easily flow between the downstream fins 33, thereby suppressing a decrease in cooling performance downstream. Furthermore, the opening area of ​​the cooling pipe 21 decreases toward the downstream side, increasing the flow velocity downstream and further suppressing a decrease in cooling performance downstream. Furthermore, the pitch p of the fins 33 gradually increases toward the downstream side, thereby reducing pressure loss of the cooling air. These features enable both improved cooling performance and reduced pressure loss. Even when the light source unit 10 is elongated or when a light source 12 with a high heat output is used, the light source 12 can be appropriately cooled by the air-cooled heat sink 31. Therefore, even when the light source unit 10 is elongated or when a light source 12 with a high heat output is used, the blower fan 11 does not need to be large, and the installation space for the blower fan 11 can be easily avoided.

[0043] Furthermore, as shown in FIG. 4, the height h and pitch p of the fins 33 are uniform in the intersecting direction, which makes it easier to suppress variations in the cooling performance and the amount of cooling air in the intersecting direction. Furthermore, the opposing surface 21m of the cooling pipe 21 that faces the surface on the LED 12 side is formed as an inclined surface that approaches the LED 12 the further downstream the cooling air is, so that a cooling pipe 21 whose opening area becomes smaller from the upstream side to the downstream side can be easily realized.

[0044] Furthermore, as shown in FIG. 4, the fins 33 are parallel to one another, which makes it easier for cooling air to flow between the fins 33. 4, the upstream fins 33 and downstream fins 33, which are adjacent to each other in the direction in which the cooling air flows and have different pitches p, overlap at least the fins 33 on the center line LC of the LED 12 in the extension direction of the cooling pipe 21. In this way, at least some of the upstream fins 33 and downstream fins 33 overlap in the extension direction of the cooling pipe 21, which makes it easier for the cooling air to flow from upstream to downstream around these fins 33, which is advantageous for improving cooling performance and reducing pressure loss.

[0045] 5, when the multiple fins 33 are viewed from the upstream or downstream side of the cooling air, there is a gap of a predetermined size or more between all of the fins 33. This gap of a predetermined size or more makes it easier for the cooling air to flow smoothly between the fins 33 from the upstream side to the downstream side of the cooling air, which is advantageous for improving cooling performance and reducing pressure loss. Furthermore, by configuring the light irradiation device to be equipped with this light source unit 10 and to irradiate light from the light source unit 10 onto an object (e.g., a printed material), it is possible to provide a light irradiation device that can easily accommodate an increase in the length of the light source unit 10 or changes to the light source 12, while suppressing an increase in the space required for the blower fan 11.

[0046] The above embodiment is merely an example of one aspect of the present invention, and can be modified and applied as desired without departing from the spirit of the present invention. For example, although the present invention has been exemplified as being applied to the light source unit 10 shown in FIG. 1 etc., the configuration, size, and shape of each part of the light source unit 10 may be changed as appropriate. Furthermore, as for the light irradiation device equipped with the light source unit 10, any appropriate device that can use this type of light source unit 10 can be applied.

[0047] The above embodiment supports the following configurations.

[0048] (Configuration 1) An air-cooled light source unit in which light sources arranged in a line are attached to a cooling pipe, a heat sink is formed on the surface of the cooling pipe facing the light source, and cooling air is supplied into the cooling pipe by a blower fan, the heat sink has a plurality of fins arranged at a predetermined pitch in a cross direction that intersects with the extension direction of the cooling pipe, the cooling pipe has a shape in which the opening area decreases from the upstream side to the downstream side of the cooling air, the height of the plurality of fins increases stepwise from the upstream side to the downstream side of the cooling air, and the pitch increases stepwise from the upstream side to the downstream side of the cooling air. With this configuration, the height of the multiple fins increases gradually toward the downstream side, making it easier for the cooling air flowing through the gaps between the upstream fins and the cooling pipe to flow between the downstream fins. Also, the opening area of ​​the cooling pipe decreases toward the downstream side, increasing the flow velocity downstream. Furthermore, the fin pitch increases gradually toward the downstream side, reducing pressure loss of the cooling air. These features enable both improved cooling performance and reduced pressure loss, making it easier for the air-cooled heat sink to properly cool the light source, even when the light source unit is elongated or a light source with a high heat output is used.

[0049] (Configuration 2) The light source unit according to configuration 1, wherein the height and the pitch of the fins are uniform in the intersecting direction. This configuration makes it easier to suppress variations in the cooling performance and the amount of cooling air in the crossing direction.

[0050] (Configuration 3) The light source unit according to configuration 1 or 2, wherein the surface of the cooling pipe facing the surface on the light source side is formed as an inclined surface that approaches the light source as it approaches the downstream side of the cooling air. According to this configuration, it is possible to easily realize a cooling pipe whose opening area decreases from the upstream side to the downstream side.

[0051] (Configuration 4) The light source unit according to any one of configurations 1 to 3, wherein the plurality of fins are parallel to one another. This configuration allows cooling air to flow easily between the fins.

[0052] (Configuration 5) A light source unit described in any one of configurations 1 to 4, wherein the upstream fin and the downstream fin, which are adjacent in the direction in which the cooling air flows and have different pitches, have at least some of the fins overlap in the extension direction of the cooling pipe. This configuration makes it easier for the cooling air to flow smoothly between the fins from the upstream side to the downstream side.

[0053] (Configuration 6) The light source unit according to any one of configurations 1 to 5, wherein when the plurality of fins are viewed from the upstream side or downstream side of the cooling air, there are gaps of a predetermined size or more between all of the fins. According to this configuration, the gaps between all of the fins are equal to or larger than a predetermined value, which makes it easier for the cooling air to flow smoothly between the fins from the upstream side to the downstream side of the cooling air.

[0054] (Configuration 7) A light irradiation device comprising the light source unit according to any one of configurations 1 to 6, which irradiates an object with light from the light source unit. According to this configuration, it is possible to provide a light irradiation device that can easily accommodate an increase in the length of the light source unit or a change in the light source, while suppressing an increase in the space required for the blower fan. [Explanation of symbols]

[0055] 10 Light source unit 11 Blower fan 12 Light source (LED) 12k board 21 Cooling pipe 21a Air intake 21b Exhaust port 21m opposite side 31, 31a to 31c, 31a1 to 31a3 Heat sink 32, 32a~32c Base part 33, 33a~33c, 33a1~33a3 Fin

Claims

1. In an air-cooled light source unit, light sources arranged in a line are attached to a cooling pipe, a heat sink is formed on a surface of the cooling pipe facing the light sources, and cooling air is supplied into the cooling pipe by a blower fan, the heat sink includes a plurality of fins arranged at a predetermined pitch in a direction intersecting an extension direction of the cooling pipe, the cooling pipe has a shape in which an opening area decreases from the upstream side to the downstream side of the cooling air, The height of the plurality of fins increases stepwise from the upstream side to the downstream side of the cooling air, and the pitch increases stepwise from the upstream side to the downstream side of the cooling air. Light source unit.

2. The height and pitch of the fins are uniform in the cross direction. The light source unit according to claim 1 .

3. The cooling pipe has a surface facing the light source side, the surface being formed as an inclined surface that approaches the light source as it approaches the downstream side of the cooling air. The light source unit according to claim 1 .

4. The fins are parallel to each other. The light source unit according to claim 1 .

5. The upstream fin and the downstream fin, which are adjacent to each other in the direction of the cooling air flow and have different pitches, at least partially overlap in the extending direction of the cooling pipe. The light source unit according to claim 1 .

6. When the plurality of fins are viewed from the upstream side or the downstream side of the cooling air, there is a gap of a predetermined size or more between all of the fins. The light source unit according to claim 1 .

7. A light source unit according to any one of claims 1 to 6, a light irradiation device that irradiates an object with light from the light source unit;

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