Light irradiation device

Abstract

The light irradiation device includes a housing an air inlet through which cooling wind is introduced into the housing, an air outlet through which the cooling wind is discharged, a wind flow path through which the cooling wind taken in through the air inlet into the housing flows toward the air outlet, a light source part configured to be able to emit light toward the outside of the housing, and a heat sink provided at a position opposite to the first surface based on the light source part, in the wind flow path, wherein the wind flow path includes a first wind flow region and a second wind flow region located closer to the air outlet than the first wind flow region and having a smaller flow path cross sectional area than the first wind flow region.

Claims

1. A light irradiation device comprising: a housing; an air inlet through which cooling wind for cooling is introduced into the housing; an air outlet through which the cooling wind is discharged to outside of the housing; a wind flow path through which the cooling wind taken in through the air inlet into the housing flows toward the air outlet; a light source part configured to be able to emit light toward the outside of the housing via a first surface that is one side surface of the housing, the light source part including a plurality of LED elements arranged along the first surface in a region of the housing located on a first surface side of the housing; and a heat sink provided at a position opposite to the first surface based on the light source part, in the wind flow path, wherein the wind flow path includes; a first wind flow region, and a second wind flow region located closer to the air outlet than the first wind flow region and having a smaller flow path cross sectional area than the first wind flow region; and the heat sink is provided across the first wind flow region and the second wind flow region.

2. The light irradiation device according to claim 1, wherein the second wind flow region is configured so that a length thereof in a direction from the air inlet to the air outlet is larger than that of the first wind flow region.

3. The light irradiation device according to claim 2, further comprising a wind shielding member provided in the wind flow path and having at least two surfaces, the wind shielding member including a wind shielding surface that shields part of the cooling wind that has flowed through the first wind flow region toward the second wind flow region, and a wind guiding surface connected to the wind shielding surface, extending along the first surface, and located closer to the air outlet than the wind shielding surface in a direction in which the wind shielding surface extends, wherein the second wind flow region is a region closer to the first surface than the wind guiding surface, and the first wind flow region is longer than the second wind flow region in a direction orthogonal to the first surface.

4. The light irradiation device according to claim 2, wherein the first wind flow region is configured to have a region whose flow path cross sectional area gradually decreases as getting close to the second wind flow region.

5. The light irradiation device according to claim 2, wherein the housing includes, in a side surface having the air outlet, a blower for discharging the cooling wind to the outside of the housing.

6. The light irradiation device according to claim 1, further comprising a wind shielding member provided in the wind flow path and having at least two surfaces, the wind shielding member including a wind shielding surface that shields part of the cooling wind that has flowed through the first wind flow region toward the second wind flow region, and a wind guiding surface connected to the wind shielding surface, extending along the first surface, and located closer to the air outlet than the wind shielding surface in a direction in which the wind shielding surface extends, wherein the second wind flow region is a region closer to the first surface than the wind guiding surface, and the first wind flow region is longer than the second wind flow region in a direction orthogonal to the first surface.

7. The light irradiation device according to claim 6, wherein the first wind flow region is configured to have a region whose flow path cross sectional area gradually decreases as getting close to the second wind flow region.

8. The light irradiation device according to claim 6, wherein the housing includes, in a side surface having the air outlet, a blower for discharging the cooling wind to the outside of the housing.

9. The light irradiation device according to claim 1, wherein the first wind flow region is configured to have a region whose flow path cross sectional area gradually decreases as getting close to the second wind flow region.

10. The light irradiation device according to claim 9, wherein the housing includes, in a side surface having the air outlet, a blower for discharging the cooling wind to the outside of the housing.

11. The light irradiation device according to claim 1, wherein the housing includes, in a side surface having the air outlet, a blower for discharging the cooling wind to the outside of the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an overall perspective view schematically showing an embodiment of a light irradiation device;

(2) FIG. 2 is an overall perspective view schematically showing the embodiment of the light irradiation device viewed in a direction different from a direction shown in FIG. 1;

(3) FIG. 3 is an overall perspective view schematically showing the embodiment of the light irradiation device viewed in a direction different from a direction shown in FIG. 1 in a state where a blower is taken off;

(4) FIG. 4 is an overall perspective view schematically showing the embodiment of the light irradiation device viewed in the same direction as shown in FIG. 1 in a state where a housing and a blower are taken off;

(5) FIG. 5 is a schematic sectional view of the XZ plane of the light irradiation device shown in FIG. 1;

(6) FIG. 6 is a schematic sectional view of the YZ plane of the light irradiation device shown in FIG. 1;

(7) FIG. 7 is a graph showing the simulation result of Examination 1;

(8) FIG. 8 is a schematic cross sectional view of the XZ plane of a light irradiation device of Comparative Example 2;

(9) FIG. 9 is a graph showing the simulation result of Examination 2;

(10) FIG. 10 is a schematic sectional view of the XZ plane of another embodiment of the light irradiation device;

(11) FIG. 11 is a schematic sectional view of the YZ plane of another embodiment of the light irradiation device; and

(12) FIG. 12 is a schematic sectional view of the XZ plane of another embodiment of the light irradiation device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) Hereinbelow, a light irradiation device according to the present invention will be described with reference to the drawings. It is to be noted that all the drawings are schematically shown, and the size ratio between components and the number of components in each of the drawings are not always the same as the actual size ratio and number.

(14) FIG. 1 is a top perspective view schematically showing an embodiment of a light irradiation device 1. FIG. 2 is an overall perspective view schematically showing the embodiment of the light irradiation device 1 viewed in a direction different from a direction shown in FIG. 1. As shown in FIG. 1 and FIG. 2, the light irradiation device 1 according to this embodiment includes a rectangular tubular housing 10, a wind flow path 11, an air inlet 12, a heat sink 13, a blower 14, a light source part 16, and an outlet 17 (see FIG. 3 described later).

(15) The air inlet 12 is provided in one side surface of the housing 10, and has the function of taking in cooling wind W1 into the housing 10. In the housing 10, the wind flow path 11 is provided to allow the cooling wind W1 taken in from the air inlet 12 flows.

(16) The heat sink 13 is provided in the housing 10 as part of the wind flow path 11. More specifically, the heat sink 13 is provided at a position opposite to a side surface 15 of the housing 10 based on the light source part 16, and so as to be thermally connected to the light source part 16 (hereinafter, also referred to as a “first surface 15”). The blower 14 is provided in a surface of the housing 10 opposite to the side surface having the air inlet 12.

(17) As shown in FIG. 2, the light source part 16 is provided by arranging a plurality of LED elements 16a along the first surface 15 in a region of the housing 10 so that light can be emitted toward the outside of the housing 10.

(18) Here, in the description of this embodiment, a direction from the air inlet 12 to the blower 14 is defined as an X direction, and a plane orthogonal to the X direction is defined as a YZ plane. Further, a plane parallel to the first surface 15 of the housing 10 having the heat sink 13 is defined as an XY plane.

(19) FIG. 3 is an overall perspective view schematically showing the embodiment of the light irradiation device 1 viewed in a direction different from a direction shown in FIG. 1 in a state where the blower 14 is taken off. As shown in FIG. 3, the air outlet 17 is provided in a surface that is opposite to the air inlet 12 and has the blower 14 shown in FIG. 1.

(20) FIG. 4 is an overall perspective view schematically showing the embodiment of the light irradiation device 1 viewed in the same direction as shown in FIG. 1 in a state where the housing 10 and the blower 14 are taken off. In the housing 10 of the light irradiation device 1, the heat sink 13 is provided over the entire first surface 15, and a wind shielding member 20 is provided so as to cover part of the heat sink 13. It is to be noted that FIG. 5 is a schematic sectional view of the XZ plane of the light irradiation device 1 shown in FIG. 1, and FIG. 6 is a schematic sectional view of the YZ plane of the light irradiation device 1 shown in FIG. 1. Hereinbelow, a description will be made with reference to FIGS. 4 to 6.

(21) As shown in FIGS. 4 to 6, the wind shielding member 20 includes a wind shielding plate 20a and a cover member 20b. The cover member 20b is provided downstream from the wind shielding plate 20a (on the air outlet 17 side) to decrease the flow path cross sectional area of the wind flow path 11.

(22) The wind shielding plate 20a constituting part of the wind shielding member 20 includes a vent 20c provided as an open region, and constitutes a wind shielding surface 30 provided on the YZ plane and having the function of shielding the cooling wind W1 traveling in the +X direction in a region other than the vent 20c provided close to the first surface 15. Part of the cooling wind W1 taken in through the air inlet 12 into the housing 10 flows in a region far from the first surface 15 in the +Z direction, travels in the +X direction, comes into collision with the wind shielding plate 20a, and then flows near the heat sink 13 through the vent 20c provided on the first surface 15 side into the downstream side of the wind shielding plate 20a. Part of the cooling wind W1 taken in through the air inlet 12 into the housing 10 flows near the first surface 15, that is, near the heat sink 13, and directly flows into the downstream side of the wind shielding plate 20a through the vent 20c while flowing near the heat sink 13.

(23) Hereinafter, a wind flow region provided in the wind flow path 11, through which the cooling wind W1 taken in into the housing 10 flows, and located upstream of the wind shielding plate 20a, that is, located on the air inlet 12 side is called “first wind flow region 21”, and a wind flow region provided in the wind flow path 11 and located downstream of the wind shielding plate 20a, that is, located on the air outlet 17 side is called “second wind flow region 22”.

(24) The cover member 20b constituting part of the wind shielding member 20 is provided in the second wind flow region 22. The cover member 20b is provided so as to cover the +Z-side region of the heat sink 13 to constitute a wind guiding surface 31. Therefore, the second wind flow region 22 is configured to have a smaller flow path cross sectional area than the first wind flow region 21, and the heat sink 13 is provided across the first wind flow region 21 and the second wind flow region 22.

(25) As shown in FIG. 5, the cooling wind W1 taken in through the air inlet 12 flows through the first wind flow region 21 and the second wind flow region 22 in the +X direction, and is discharged from the air outlet 17 through the blower 14. The example shown in FIG. 5 is configured so that the length of the second wind flow region 22 in the X direction is longer than that of the first wind flow region 21 in the X direction.

(26) As described above, the cooling wind W1 flowing through the first wind flow region 21 is guided to the vent 20c provided in the wind shielding plate 20a. Then, the cooling wind W1 that has passed through the vent 20c flows through the second wind flow region 22 whose flow path cross sectional area is smaller than that of the first wind flow region 21. Therefore, the cooling wind W1 flowing through the second wind flow region 22 has a flow rate higher than that of the cooling wind W1 flowing through the first wind flow region 21 according to the Bernoulli's theory.

(27) As described above, the cooling wind W1 flowing through the second wind flow region 22 that is a downstream part of the wind flow path 11 has a flow rate higher than that of the cooling wind W1 flowing through the first wind flow region 21, and therefore the heat rejection efficiency of the heat sink 13 in the downstream part is improved as compared with conventional structures. Therefore, the light irradiation device 1 according to this embodiment can achieve improved uniformity of heat rejection efficiency from the upstream part to the downstream part without increasing the size of the heat sink 13 and changing the shape of the heat sink 13 so that a temperature difference in the entire light source part 16 is reduced. This makes it possible to improve the uniformity of the intensity of light emitted from each LED element 16a arranged in the light source part 16 without increasing the entire size of the light irradiation device 1.

Examination 1

(28) First, in order to confirm the effect of the above-described embodiment, simulation was performed to compare temperature distribution between a conventional structure and the above-described embodiment, and the result of the simulation is shown.

(29) The comparison was made between a conventional structure (Comparative Example 1) in which the flow path cross sectional area of the wind flow path 11 in the X direction was constant throughout the wind flow path 11 and the light irradiation device 1 shown in FIG. 1 (Example 1).

Example 1

(30) The length (length in the X direction) and width (length in the Y direction) of the wind flow path 11 were 330 mm and 90 mm, respectively, and the length (length in the X direction) of the second wind flow region 22 was 198 mm. Further, the height (length in the Z direction) of the heat sink 13 provided in the wind flow path 11 was 29 mm. The light source part 16 was provided by arranging the plurality of LED elements 16a in a matrix in the housing 10, and the heat sink 13 was provided in a direction opposite to the light emission direction of the light source part 16. The region where the light source part 16 was provided had an X×Y size of 325 mm×50 mm, and was located inside the region where the heat sink 13 was provided on the XY plane.

(31) The height of the first wind flow region 21 from the first surface 15 was 95 mm, and the height of the second wind flow region 22 from the first surface 15 was 30 mm. The wind shielding plate 20a was provided on the YZ plane.

Comparative Example 1

(32) The height of the wind flow path 11 from the first surface 15 was 95 mm. That is, Comparative Example 1 was the same as Example 1 except that neither of the first wind flow region 21 and the second wind flow region 22 were provided.

Simulation Method

(33) The LED elements 16a constituting the light source part 16 were turned on while cooling wind W1 was taken in through the air inlet 12 at a wind speed of 7 m/s, and when the LED elements 16a reached a steady state, temperature distribution was calculated at 20 calculation points located at the center of the light source part 16 in the Y direction at even intervals in the X direction.

Result

(34) FIG. 7 is a graph showing the simulation result of Examination 1. FIG. 7 indicates that in the case of Comparative Example 1 (conventional structure), the temperatures of the LED elements 16a located at position 18 and position 19 were highest (78.6° C.) and the temperature of the LED element 16a located at position 2 was lowest (60.6° C.). As a result, the difference between the highest temperature and the lowest temperature was 18.0° C.

(35) On the other hand, in the case of Example 1 (structure according to the present invention), the temperature of the LED element 16a located at position 5 was highest (76.4° C.), and the temperature of the LED element 16a located at position 10 was lowest (71.6° C.). As a result, the difference between the highest temperature and the lowest temperature was 4.8° C.

(36) From the result, it can be confirmed that the temperature difference depending on the position of the LED element 16a of Example 1 was reduced as compared with that of Comparative Example 1. Further, it can also be confirmed that the highest temperature of Example 1 (structure according to the present invention) did not exceed the highest temperature of Comparative Example 1 (conventional structure), and the temperatures of the LED elements 16a did not increase to the extent that the LED elements 16a were turned off.

Examination 2

(37) Then, the relationship between the lengths of the first wind flow region 21 and the second wind flow region 22 in the X direction and the temperature difference among the LED elements 16a located at different positions was examined.

(38) More specifically, simulation was performed to examine how the temperature difference between the highest temperature and the lowest temperature in the entire light source part 16 was changed when the lengths of the first wind flow region 21 and the second wind flow region 22 in the X direction were changed. Simulation conditions are as follows.

Example 2

(39) The length (length in the X direction) and width (length in the Y direction) of the wind flow path 11 were 306 mm and 90 mm, respectively, and the length (length in the X direction) of the second wind flow region 22 was 175 mm. Further, the height (length in the Z direction) of the heat sink 13 provided in the wind flow path 11 was 29 mm. The light source part 16 was provided by arranging the plurality of LED elements 16a in a matrix in the housing 10, and the heat sink 13 was provided in a direction opposite to the light emission direction of the light source part 16. The region where the light source part 16 was provided had an X×Y size of 325 mm×50 mm, and was located inside the region where the heat sink 13 was provided on the XY plane.

(40) The height of the first wind flow region 21 from the first surface 15 was 95 mm, and the height of the second wind flow region 22 from the first surface 15 was 30 mm. The wind shielding plate 20a was provided on the YZ plane.

Example 3

(41) The length (length in the X direction) of the second wind flow region 22 was 191 mm. Example 3 was the same as Example 1 except that the length (length in the X direction) of the second wind flow region 22 was changed.

Example 4

(42) The length (length in the X direction) of the second wind flow region 22 was 205 mm. Example 4 was the same as Example 1 except that the length (length in the X direction) of the second wind flow region 22 was changed.

Example 5

(43) The length (length in the X direction) of the second wind flow region 22 was 255 mm. Example 4 was the same as Example 1 except that the length (length in the X direction) of the second wind flow region 22 was changed.

Comparative Example 2

(44) The length (length in the X direction) of the second wind flow region 22 was 306 mm. FIG. 8 is a schematic cross sectional view of the XZ plane of a light irradiation device 1 of Comparative Example 2. As shown in FIG. 8, the height (length in the Z direction) of the wind flow path 11 is constant throughout its length. The other conditions were the same as those in Example 1.

Simulation Method

(45) The LED elements 16a constituting the light source part 16 were turned on while cooling wind W1 was taken in through the air inlet 12 at a wind speed of 7 m/s, and when the LED elements 16a reached a steady state, the temperature of the light source part 16 was measured throughout the first surface 15 to calculate a temperature distribution.

Result

(46) FIG. 9 is a graph showing the simulation result of Examination 2. As can be seen from FIG. 9, the temperature difference in the entire light source part 16 was smaller in all the Examples 2 to 5 than in the conventional structure (Comparative Example 2). Further, the temperature difference gradually decreases as the length (length in the X direction) of the second wind flow region 22 decreases, however, on the other hand, when the length (length in the X direction) of the second wind flow region 22 is 175 mm (Example 2) or 191 mm (Example 3) which is smaller than 198 mm (Example 1), the temperature difference is larger.

(47) At present, the present inventors presume that the cause of the fact that the temperature differences in Example 2 and Example 3 were larger than the temperature difference in Example 1 is as follows. When the length (length in the X direction) of the first wind flow region 21 where the flow rate does not increase is large as in Examples 2 and 3, a region where heat rejection efficiency is reduced is created in part of the heat sink 13.

(48) Further, the velocity of the cooling wind W1 is higher throughout the wind flow path 11 in a structure in which the heat sink 13 is entirely covered with the cover member 20b, such as Comparative Example 2 shown in FIG. 8 than in a structure in which the cover member 20b is not provided. However, as shown in FIG. 9, the temperature difference in the entire light source part 16 is not improved even when the velocity is increased throughout the wind flow path 11.

(49) The optimum length (length in the X direction) of the second wind flow region 22 varies depending on, for example, the size or shape of the wind flow path 11, however, under the conditions of this examination, when the length (length in the X direction) of the second wind flow region 22 is 198 mm (Example 3) longer than 153 mm that is half the length of the wind flow path 11, the temperature difference in the entire light source part 16 is smallest. Based on the above-described reason, this fact reveals that the length (length in the X direction) of the second wind flow region 22 is preferably longer than the length (length in the X direction) of the first wind flow region 21.

Another Embodiment

(50) Hereinbelow, another embodiment will be described.

(51) <1> FIG. 10 is a schematic sectional view of the XZ plane of another embodiment of the light irradiation device 1. As shown in FIG. 10, the wind shielding member 20 may not be one constituted from the wind shielding plate 20a and the cover member 20b. FIG. 10 shows, as an example, a rectangular parallelepiped wind shielding member 20 having a wind shielding surface 30 and a wind guiding surface 31. The wind shielding surface 30 shields part of cooling wind W1 travelling in the +X direction, and the wind guiding surface 31 is provided to make the height of the wind flow path 11 from the first surface 15 lower than the height of the first wind flow region 21.

(52) It is to be noted that in this case, the wind shielding member 20 may be hollow. When the wind shielding member 20 shown in FIG. 10 is hollow, the entire size of the light irradiation device 1 can be reduced by placing the power source etc. of the blower 14 inside the wind shielding member 20.

(53) <2> FIG. 11 is a schematic sectional view of the YZ plane of another embodiment of the light irradiation device 1. As shown in FIG. 11, the light irradiation device 1 according to this embodiment includes two wind shielding members 20 provided in the housing 10. In this way, a plurality of wind shielding members 20 may be provided.

(54) <3> FIG. 12 is a schematic sectional view of the XZ plane of another embodiment of the light irradiation device 1. As shown in FIG. 12, the first wind flow region 21 may be configured so that the height thereof from the first surface 15 gradually decreases toward the second wind flow region 22, that is, the first wind flow region 21 has a region that gradually becomes small toward the second wind flow region 22.

(55) <4> In each of the embodiments, the wind flow path 11 having a rectangular parallelepiped shape is shown as an example to explain a reduction in the flow path sectional area, but the wind flow path 11 may be configured so that part of air flowing in the wind flow path 11 flows in a direction different from the direction from the air inlet 12 to the air outlet 17.

(56) <5> The above-described structures are merely examples of the structure of the light irradiation device 1, and the present invention is not limited to these structures shown in the drawings.