JP4736418B2 - Light irradiation device - Google Patents

Description

  The present invention relates to a light irradiation apparatus having an LED as a light source, and takes measures against heat of the LED.

  In recent years, with the increase in brightness of LEDs, LEDs have been used as light sources for various devices. As an example, there is one using a high-intensity LED as a light source of a liquid crystal projector (see, for example, Patent Document 1). By using the LED, there is an advantage that the apparatus can be downsized and the lighting control of the light source can be easily performed as compared with the case where a conventional halogen lamp or xenon lamp is used. However, since it is necessary to flow a large current in order to increase the brightness of the LED light, the heat generation of the LED itself cannot be ignored, and the LED may be damaged by heat unless heat countermeasures are taken. For example, Patent Documents 2 and 3 disclose devices that take measures against heat of LEDs.

JP 2000-194275 A JP 2004-4581 A JP 2004-69825 A

  The countermeasures against heat in Patent Documents 2 and 3 require the addition of a heat conductive heat dissipation member, a Peltier element for cooling, etc., so the number of parts is increased, and there has been no effort to efficiently release heat to the outside. , Heat dissipation is insufficient.

The invention of claim 1, Oite the light irradiation device that emits LED light positioned in the housing to the outside, along with the LED provided a metallic substrate which is mounted on the surface, at least a part of the housing It is made of metal and the board is fixed to the metal part so that at least the back side of the board where the LED is mounted is in close contact with the inner surface of the metal part of the housing directly or with a sheet member with high thermal conductivity and, heat generated from the LED is characterized by being configured to be released to the outside through the substrate and the metal parts.
According to a third aspect of the present invention, in the light irradiation device for emitting the light of the LED disposed in the casing to the outside, at least a part of the casing is made of metal, and the LED is directly mounted on the inner surface of the metal portion of the casing. And at least a portion corresponding to the back surface of the portion where the LED is mounted is exposed to the outside of the outer surface of the metal portion, and heat generated from the LED is released to the outside through the metal portion. To do .

  According to the present invention, at least a part of the housing is made of metal, the LED is mounted on a metal substrate, and the substrate is fixed to the metal portion of the housing, or the LED is mounted on the inner surface of the metal portion of the housing. Since the LED is directly mounted, the heat generated from the LED can be efficiently transmitted to the casing and released from the casing to the outside. Therefore, a highly efficient heat dissipation structure can be realized without separately providing a heat dissipation fan or a Peltier element.

An embodiment in which the present invention is applied to a liquid crystal projector will be described with reference to FIGS.
FIG. 1 is a front view of a liquid crystal projector according to the present embodiment, and FIG. 2 is a sectional view taken along line II-II. The projector housing 10 is made of a metal having good thermal conductivity as a material, and is made of, for example, aluminum die casting. Legs 11b are provided at the four corners of the lower surface 11a of the housing 10, and a gap is formed between the placement surface P and the housing lower surface 11a when placed on a desk or the like.

The following components are accommodated in the housing 10.
A high-intensity LED 1 as a light source is mounted on a metal LED board 2. The LED substrate 2 is formed, for example, by forming a conductor circuit on the upper surface of an aluminum plate via a heat conductive insulating layer. The LED 1 is mounted on the upper surface, and the lower surface 2a has a metal portion exposed. The substrate 2 is disposed such that the lower surface 2a thereof is in close contact (surface contact) with the bottom surface 11c of the housing 10, and is fixed by screws BS. Concave and convex fins 12 are formed in the lower portion of the substrate 2 on the lower surface 11 a of the housing.

  A liquid crystal panel 3 as an image forming member is disposed above the LED substrate 2, and a PBS (Polarized Beam Spritter) 4 is disposed above the liquid crystal panel 3. The PBS film 4a forms an angle of 45 degrees with respect to the optical axis of the LED light. A quarter-wave plate 5 and a reflection mirror 6 are provided behind the PBS 4. The mirror 6 constitutes a projection optical system, and its reflection surface is spherical or aspheric.

  A control IC 8 is mounted on the control circuit board 7 disposed behind the mirror 6, and one end of an external cable (for example, USB cable) 9 is connected to the control circuit board 7. The control IC 8 is electrically connected to the LED substrate 2 and the liquid crystal panel 3 via the wiring member 21. Electric power and a control signal are supplied from an external device (not shown) via the cable 9, and the control IC 8 performs lighting control of the LED 1 and drive control of the liquid crystal panel 3 in accordance with the input signal.

  When an image is formed on the liquid crystal panel 3 and the LED 1 is turned on, the LED light passes through the liquid crystal panel 3, reaches the PBS 4, and is reflected backward by the PBS film 4a. The reflected light passes through the quarter-wave plate 5, is reflected forward by the reflection mirror 6, and passes through the quarter-wave plate 5 again. Light that has undergone polarization conversion by passing through the quarter-wave plate 5 twice passes through the PBS 4 and is projected to the outside through a diaphragm 22 provided near the exit. By using such an optical system, chromatic aberration can be reduced to a minimum while being compact.

The LED 1 generates a considerable amount of heat because a large current flows, but the heat is transmitted to the metal LED substrate 2 and further radiated to the outside through the metal housing 10. As described above, since the substrate lower surface 2a is in close contact (surface contact) with the housing bottom surface 11c, the heat of the LED 1 can be efficiently transmitted to the housing 10. Further, the housing 10 has an extremely large area in contact with the external space, and can efficiently release the heat to the outside. In particular, in the lower surface 11a of the housing, the portion immediately below the LED substrate 2 has the highest temperature. Since the fin 12 is formed in this portion, the heat radiation efficiency is increased due to the increase in the heat radiation area. Therefore, even if a large current is passed through the LED 1, the LED 1 can be prevented from being damaged by heat. In addition, it is not necessary to add a heat radiating fan, a metal heat radiating member, a Peltier element, etc. as in the prior art, and the number of parts does not increase substantially.
In addition, since the clearance gap between the housing | casing lower surface 11a and the mounting surface P is open | released by the four directions, heat does not remain in this part.

Furthermore, providing the LED 1 near the bottom surface of the housing 10 as described above is advantageous in the following two points.
First, the heat of the LED 1 is mainly dissipated from the lower surface 11a of the housing, in other words, the portion of the housing 10 that has the highest temperature can be the lower surface 11a. Since the lower surface 11a is the place where the user is least likely to touch the hand directly, the user hardly feels discomfort due to heat. Further, when the LED 1 is disposed near the bottom surface of the housing 10, it is possible to realize a configuration in which the LED light is irradiated upward as shown in the figure and is bent and projected in the horizontal direction. This configuration has good space efficiency, and the projection optical axis L can be set as high as possible, that is, a position away from the installation surface P without increasing the size of the housing 10. Incidentally, when the projection optical axis L is close to the installation surface P, it is difficult to project on the external screen, and it is necessary to consider that the projection is performed obliquely upward.

  An elastic sheet having a high thermal conductivity may be sandwiched between the lower surface 2a of the LED substrate 2 and the housing bottom surface 11c. According to this, even if there are irregularities on both surfaces 2a and 11c, they are absorbed to improve the adhesion and the heat conduction efficiency is not impaired.

3 and 4 show another embodiment, which is an example in which the LED 1 is directly mounted on the bottom surface of a metal casing 10 '. Components having the same functions as those in FIGS. 1 and 2 are denoted by the same reference numerals.
A conductor circuit is formed on the upper surface of the mounting portion 31 formed integrally with the bottom surface 11c of the housing via an insulating layer, and the LED 1 can be directly mounted thereon. The fin 12 is formed in the location located in the lower part of the mounting part 31 among the housing | casing lower surface 11a similarly to the above-mentioned. According to this configuration, the heat of the LED 1 is directly transmitted to the housing 30, so that the heat conduction efficiency, that is, the heat dissipation efficiency is higher than that of the previous embodiment, and the LED board is not necessary, so the number of parts can be reduced. I can plan.

  In addition, the arrangement | positioning position of LED does not receive a restriction | limiting in particular, The attachment location of the LED board 2 and the formation location of the mounting part 31 are not limited to a bottom face. Moreover, although the example which made the whole housing | casing made from metal was shown, the attachment location of the LED board 2 and the formation location of the mounting part 31 may be made into metal, and another part may be comprised with a plastics etc. Further, the image forming member is not limited to the transmissive liquid crystal panel, and may be a reflective liquid crystal or another type. Further, as described with reference to the projector, the present invention can be applied to other light irradiation devices using LEDs as light sources, for example, cameras equipped with LED flashes, cameras using LEDs as light sources of AF auxiliary light, and the like.

The front view of the projector in 1st Embodiment. II-II sectional view taken on the line of FIG. The front view of the projector in 2nd Embodiment. IV-IV sectional view taken on the line of FIG.

Explanation of symbols

1 LED
2 LED board 3 Liquid crystal panel 4 PBS
4a PBS film 5 1/4 wavelength plate 6 reflecting mirror 7 control circuit board 10, 10 'housing 11a housing lower surface 11c housing bottom surface 11b leg 12 fin L projection optical axis P mounting surface

Claims (6)

In the light irradiation device for emitting the light of the LED arranged in the housing to the outside,
A metal substrate on which the LED is mounted is provided, and at least a part of the housing is made of metal, and at least the back surface of the portion where the LED is mounted is directly or thermally conductive. The substrate is fixed to the metal portion so as to be in close contact with the inner surface of the metal portion of the casing with a highly flexible sheet member interposed therebetween, and heat generated from the LED is released to the outside through the substrate and the metal portion. The light irradiation apparatus characterized by being comprised . The surface to which the substrate is closely attached is the bottom surface of the housing, and the light irradiated upward from the LED is configured to be irradiated to the outside in a substantially horizontal direction via an optical path changing member provided in the housing. The light irradiation apparatus according to claim 1. In the light irradiation device for emitting the light of the LED arranged in the housing to the outside,
At least a part of the housing is made of metal, and the LED is directly mounted on the inner surface of the metal portion of the housing, and at least the portion corresponding to the back surface of the outer surface of the metal portion where the LED is mounted Is exposed to the outside, and heat generated from the LED is configured to be released to the outside through the metal portion . The mounting surface of the LED is a bottom surface of the housing, and the light irradiated upward from the LED is configured to be irradiated to the outside in a substantially horizontal direction via an optical path changing member provided in the housing. The light irradiation apparatus according to claim 3 . An image forming member for forming an image for projection and a projection optical system are further provided, and light from the LED is projected to the outside in a substantially horizontal direction via the image forming member, the optical path changing member, and the projection optical system. The light irradiation apparatus according to claim 2, wherein: The light irradiation apparatus according to claim 1, wherein a heat radiation fin is formed at a position closest to the LED on an outer surface of the housing .

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