JPWO2020158603A1 - Head-up display - Google Patents

Abstract

Provided is a head-up display capable of improving heat dissipation of a heat sink. A circuit board 33 on which the LED 31 and the wiring 37 connected to the LED 31 are mounted, a base 41 having one surface 41a on which the circuit board 33 is arranged and the other surface 41b which is the opposite surface of the one surface, and a base 41. It has a plurality of first heat radiating fins 44 protruding from the other surface 41b, and a plurality of second heat radiating fins 45 intersecting with each first heat radiating fin 44 protruding from the other surface 41b to form an intersection 48. It comprises a heat sink 35 formed of a high thermal conductive resin material. The intersection 48 is formed at a position where it overlaps with the wiring 37 via the base 41.

Description

The present disclosure relates to a head-up display provided with a lighting device used for transmission lighting of a display device.

In a head-up display, as a conventional technique relating to a lighting device used for transmission lighting of a display device, for example, there is a technique disclosed in Patent Document 1. The lighting device of Patent Document 1 has a heat sink having a plurality of heat radiating portions, which is made of a high thermal conductive resin. Further, the lighting device has a circuit board on which a plurality of light sources are mounted, which are superposed on the heat sink. At least a part of the heat radiating portion is arranged at a position overlapping with respect to the plurality of light sources when viewed from the tip side of the plurality of heat radiating portions.

Japanese Unexamined Patent Publication No. 2018-137089

The lighting device of Patent Document 1 is intended to efficiently dissipate heat dissipated from a light source from a heat radiating portion close to the light source. However, with the increasing brightness of today's light sources, it is required to further improve heat dissipation efficiency.

The present disclosure has been made in consideration of such circumstances, and an object of the present invention is to provide a head-up display capable of improving the heat dissipation of a heat sink.

In the head-up display of the present disclosure, in order to solve the above-mentioned problems, a circuit board on which an LED and wiring connected to the LED are mounted, one surface on which the circuit board is arranged, and one of the circuit boards are mounted. A plurality of bases having the other surface, which is the opposite surface of the surface, a plurality of first heat radiating fins protruding from the other surface, and a plurality of intersecting points of the first heat radiating fins protruding from the other surface. The second heat dissipation fins of the above are provided, and a heat sink formed of a high thermal conductive resin material is provided, and the intersection is formed at a position overlapping with the wiring via the base.

In the head-up display of the present disclosure, the heat dissipation of the heat sink can be improved.

An explanatory view of a vehicle equipped with a head-up display according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view of the head-up display shown in FIG. An exploded perspective view of the lighting device shown in FIG. 2. The block diagram of the circuit board seen from the mounting surface of a light source. A block diagram of the heat sink as seen from the heat dissipation part side. Explanatory drawing which shows the relationship between a circuit board and a 1st heat radiation fin and a 2nd heat radiation fin.

The embodiments of the present disclosure will be described below with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of a vehicle 10 equipped with a head-up display 20 according to the embodiment of the present disclosure.
FIG. 2 is a cross-sectional view of the head-up display 20 shown in FIG.
FIG. 3 is an exploded perspective view of the lighting device 23 shown in FIG.
In the figure, Up indicates the upper part and Dn indicates the lower part.

As shown in FIG. 1, a vehicle 10 such as a passenger car is provided with a dashboard 12 at the front of the passenger compartment 11. The dashboard 12 has a head-up display 20 built in the upper part. The display light Ld projected from the head-up display 20 is displayed as an image on the windshield 13 of the vehicle 10. The driver can visually recognize the virtual image Vi together with the background in front of the vehicle 10.

As shown in FIG. 2, the head-up display 20 includes a display device 21 (projector 21) that projects display light Ld, a reflector 22 that reflects the projected display light Ld, and transmitted illumination of the display device 21. The lighting device 23 used in the above. The display device 21, the reflector 22, and the lighting device 23 are housed in the storage box 24. As shown in FIG. 2, the storage box 24 includes a transmission unit 25 capable of transmitting the display light Ld projected from the display device 21 to the outside.

The display device 21 displays various information such as traveling information, and is configured by, for example, a liquid crystal display device. This liquid crystal display device employs, for example, a TFT type liquid crystal panel as a display medium (display element). In addition to the liquid crystal panel, this liquid crystal display device includes a circuit board on which a control unit for controlling the display of the liquid crystal panel is mounted, a flexible wiring board for electrically connecting the liquid crystal panel and the circuit board, and the like. Has (not shown).

The reflector 22 is composed of a concave mirror that magnifies the display light Ld projected from the display device 21 and reflects it toward the windshield 13 (see FIG. 1).

As shown in FIGS. 2 and 3, the lighting device 23 includes a plurality of light sources 31 used for transmitted illumination of the display device 21 and a lens array 32 that equalizes the illuminance distribution of the light emitted by the plurality of light sources 31. And the circuit board 33 on which the plurality of light sources 31 are mounted on the mounting surface 33a, and the heat sink 35 laminated on the back surface 33b (the surface opposite to the mounting surface 33a) of the circuit board 33 via the heat conductive sheet 34. And, including. The plurality of light sources 31, the lens array 32, the circuit board 33, and the heat conductive sheet 34 are housed in the case 36.

As shown in FIG. 3, the case 36 can be attached to the base 41 by a plurality of screw members 51 (for example, screws 51). A plurality of insert nuts 52 for connecting the plurality of screw members 51 are embedded in the base 41. The plurality of insert nuts 52 are made of a metal material and are integrally embedded in the base 41.

As shown in FIG. 3, the plurality of light sources 31 are composed of, for example, a surface mount type LED (Light Emitting Diode). Here, FIG. 4 is a configuration diagram of the circuit board 33 as seen from the mounting surface 33a of the light source 31.

The plurality of light sources 31 (two in the vertical direction and three in the horizontal direction (direction orthogonal to the vertical direction) in FIG. 4) are arranged on the mounting surface 33a of the circuit board 33 at a predetermined pitch. Each light source 31 has a pair of anode terminals 36a (terminals on the anode electrode side) and cathode terminals 36b (terminals on the cathode electrode side) mounted on the mounting surface 33a by soldering. In the plurality of light sources 31, the anode terminal 36a of one light source 31 (for example, light source 31a) adjacent in the vertical direction and the cathode terminal 36b of another light source 31 (for example, light source 31b) are connected in series by wiring (copper foil wiring pattern) 37. It is connected and mounted on the circuit board 33. In FIG. 4, the wiring 37 is shown by hatching for the sake of explanation. One end of the wiring 37 is connected to the anode electrode 38a mounted on the circuit board 33. The other end of the wiring 37 is connected to the cathode electrode 38b mounted on the circuit board 33. As a result, the light source 31 is connected in series by the wiring 37 in a string of beads.

The circuit board 33 has an insulating layer (for example, a glass epoxy board) formed on a metal plate material (for example, an aluminum alloy) having excellent thermal conductivity, and a light source 31 and a wiring 37 are provided on the mounting surface 33a (front surface) of the insulating layer. It is composed of the formed metal-based circuit board. The mounting surface 33a of the circuit board 33 faces the incident surface of the lens array 32. The surface of the back surface 33b where the metal plate material is exposed faces the heat sink 35.

Further, as shown in FIG. 4, the wiring 37 is formed as a heat dissipation pattern that extends in the surface direction of the mounting surface 33a so as to have a surface area as large as possible and extends in a substantially rectangular shape or the like. This heat dissipation pattern is formed so as to be at least wider than the light source 31 (longer in the left-right direction) and shorter in the wiring length between the light sources 31.

The heat conductive sheet 34 is a sheet made of a resin such as silicone, acrylic, or polyolefin having good heat conductivity that is flexible and has excellent adhesion, and efficiently transfers the heat of the circuit board 33 to the heat sink 35. Further, the heat conductive sheet 34 may have improved heat conductivity by blending a metal filler such as a ceramic filler with a resin base material.

As shown in FIGS. 2 and 3, the heat sink 35 is a molded product made of a highly thermally conductive resin material. In the present disclosure, the high thermal conductive resin is a mixture of a resin such as nylon and a high thermal conductive filler such as a ceramic filler, and has a thermal conductivity (thermal conductivity coefficient) of at least 1.0 W / (m · K) or more. Is defined as a mixed resin. As the high thermal conductive filler, for example, a filler having insulating properties such as aluminum oxide, boron nitride, and aluminum nitride, which are a kind of ceramics, is preferable. However, if it is desired to improve heat dissipation, a filler having no electrical insulation such as aluminum, copper, or graphite may be selected as the high thermal conductive filler. To show an example of the thermal conductivity in each configuration, the nylon resin alone has a thermal conductivity of 0.22 to 0.43 W / (m · K). On the other hand, the thermal conductivity of the highly thermally conductive resin obtained by mixing the nylon resin with the ceramic filler having electrical insulation is about 5 W / (m · K). In addition, the thermal conductivity of the high thermal conductivity resin, which is a mixture of nylon resin and a filler that does not have electrical insulation, is about 50 W / (m · K), and the high thermal conductivity resin has higher thermal conductivity than ordinary resins. Become. The heat sink 35 formed of the high thermal conductive resin material includes a base 41 stacked on the heat conductive sheet 34, and a plurality of heat radiating portions 42 extending from the base 41 to the side opposite to the heat conductive sheet 34.

FIG. 5 is a configuration diagram of the heat sink 35 as viewed from the heat radiating portion 42 side.

The overall shape of the heat sink 35 is substantially rectangular when viewed from the heat radiating portion 42 side.

The base 41 has a substrate side surface 41a as one surface facing the back surface 33b of the circuit board 33, and a heat dissipation portion side surface 41b as the other surface opposite to the substrate side surface 41a (FIG. 2). The substrate side surface 41a is a surface that supports the heat conductive sheet 34 (circuit board 33). The side surface 41b of the heat radiating portion is a surface on the side where the heat radiating portion 42 is formed. The side surface 41a of the substrate and the side surface 41b of the heat radiating portion have a flat flat plate shape, and the surface direction of the base 41 is set to be substantially vertical (substantially vertical direction) in the usage state of the lighting device 23.

The heat radiating portion 42 is surrounded by a square cylindrical frame portion 43. The frame portion 43 extends from the edge of the heat radiating portion side surface 41b of the base 41 along the projecting direction of the heat radiating portion 42, and is integrally molded with the base 41 together with the heat radiating portion 42. The heat radiating portion 42 has a plurality of first heat radiating fins 44 protruding from the side surface 41b of the radiating portion, and a plurality of second heat radiating fins 45.

The plurality of first heat radiating fins 44 extend to one side along the side surface 41b of the heat radiating portion. Specifically, the first heat radiation fin 44 extends with a slight inclination with respect to the vertical direction. The plurality of second heat radiating fins 45 extend in a direction intersecting the plurality of first heat radiating fins 44 along the side surface 41b of the heat radiating portion. Specifically, the second heat radiating fin 45 has a slight inclination with respect to the left-right direction and extends so as to be orthogonal to the first heat radiating fin 44 in a grid pattern. The first heat radiation fin 44 and the second heat radiation fin 45 form a plurality of intersection points 48.

The tip 44a of the first heat radiation fin 44 extends beyond the tip surface 43a of the frame portion 43 (FIG. 2). On the other hand, the tip 45a of the second heat radiation fin 45 is shorter than the tip 44a of the first heat radiation fin 44 and is located on the side surface 41b side of the heat radiation portion. In general, the heat radiation fins having a horizontal plate shape (extending substantially in the left-right direction) tend to suppress the updraft of radiant heat dissipated from the plurality of heat radiation portions 42. On the other hand, in the present embodiment, the length of the second heat radiation fin 45 extending substantially in the left-right direction is kept short. Therefore, the hot air dissipated from the plurality of heat radiating portions 42 can be efficiently dissipated without being trapped in the vicinity thereof.

The heat radiating unit 42 further has a plurality of third heat radiating fins 46. The third heat radiation fin 46 projects from the side surface 41b of the heat radiation portion between the first heat radiation fins 44 so as to be smaller than the first heat radiation fin 44 and larger than the second heat radiation fin 45. Since the third heat radiating fin 46 has a shorter length than the first heat radiating fin 44, it is possible to reduce the fins from being cracked and damaged when the heat sink 35 is pulled out from the mold during molding.

The third heat radiating fin 46 extends in a direction intersecting the plurality of second heat radiating fins 45 while being substantially parallel to the first heat radiating fin 44 along the side surface 41b of the heat radiating portion. The third heat radiation fin 46 and the second heat radiation fin 45 form a plurality of intersection points 49. By having the intersection 49, the heat sink 35 can increase the surface area and increase the radiant heat transfer. Unlike the first heat radiation fin 44, the third heat radiation fin 46 is not a vertical plate extending substantially in the vertical direction, but a vertical plate intermittently provided at a position intersecting the second heat radiation fin 45. As a result, the surface area of the heat radiating portion 42 can be increased, and the heat radiating property can be improved.

Here, when the wiring 37 connected to the light source 31 is formed as a heat dissipation pattern extending in the plane direction of the mounting surface 33a, the heat generated by the light source 31 is efficiently transferred to the wiring 37, so that the heat generated by the light source 31 is efficiently transmitted to the wiring 37, so that the heat generated by the light source 31 is more efficiently transmitted to the wiring 37. It was found that the wiring 37 connected to the light source 31 had a higher temperature. Therefore, it was found that cooling the wiring 37 connected to the light source 31 is more effective in protecting the light source 31 than directly under the light source 31. In particular, the surface mount type light emitting diode used as the light source 31 has a structure in which a cathode terminal side lead frame provided with an LED chip and an anode side lead frame are electrically connected by a bonding wire, and the cathode terminal 36b. Since heat is easily transferred to the wiring 37 on the side connected to the cathode terminal 36b and the temperature becomes high, it is effective to preferentially cool the wiring 37 on the side connected to the cathode terminal 36b to protect the light source 31. But I understand. Therefore, the lighting device 23 in the present embodiment is configured with a heat sink 35 so as to improve heat dissipation. Hereinafter, a specific description will be given.

Here, FIG. 6 is an explanatory diagram showing the relationship between the circuit board 33 and the first heat radiation fins 44 and the second heat radiation fins 45. In FIG. 6, the first heat radiation fin 44 and the second heat radiation fin 45 facing the circuit board 33 via the base 41 are shown by dotted lines. As shown in FIG. 6, each intersection 48 of the first heat radiation fin 44 and the second heat radiation fin 45 described above is formed at least at a position overlapping with the wiring 37 via the base 41. As a result, the wiring 37 that generates a large amount of heat is thermally connected (closely) to the intersection 48 having a large surface area and high heat dissipation due to radiant heat transfer, and the heat generation efficiency of the lighting device 23 can be improved. .. In particular, when the heat sink 35 is made of a highly thermally conductive resin, increasing the surface area of the portion near the heat generating portion to increase the amount of radiant heat transfer is advantageous from the viewpoint of heat dissipation as compared with increasing the heat capacity. ..

In the example of FIG. 6, the anode terminals 36a and cathode terminals 36b of the plurality of light sources 31 arranged in the vertical direction and the horizontal direction (the first direction and the second direction orthogonal to the first direction) extend from the light source 31. When the direction is the vertical direction, the wiring 37 has a plurality of substantially rectangular regions connecting the terminals 36a and 36b in the vertical direction. Further, for example, the anode terminal 36a of the light source 31c located at the lower end in the vertical direction is the cathode terminal 36b of the light source 31d located at the upper end adjacent to the right direction. In this case, the wiring 37 connecting the anode terminal 36a of the light source 31c and the cathode terminal 36b of the light source 31d is connected by a linear connection region 37c extending in the vertical direction connecting the rectangular region 37a and the rectangular region 37b. Has a rectangular shape. In such a case, the "wiring 37 connected to the cathode terminal 36b" refers to the rectangular region 37b.

Further, the intersection 48 is preferably formed at a substantially center of each wiring 37 (for example, a substantially center position of a rectangle). As a result, the entire range on each wiring 37 can be cooled uniformly, and the heat dissipation can be further improved.

Further, the intersection 48 is formed closer to the cathode terminal 36b, which generates more heat when the anode terminal 36a and the cathode terminal 36b are located in the vertical direction in one rectangular region of the wiring 37 (for example, the rectangular region 37d in FIG. 6). It may have been done.

In the lighting device 23 and the head-up display 20 in the present embodiment as described above, since the heat sink 35 is appropriately designed according to the heat generation portion of the light source 31, the heat dissipation of the heat sink 35 can be improved.

Although some embodiments have been described in the present disclosure, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

For example, the head-up display of the present disclosure has been described as an example when it is mounted on a vehicle 10, but it is also applicable to other vehicles and is not limited to those of these types.

Further, the heat sink 35 may be configured to be stacked on the back surface 33b of the circuit board 33 without a heat conductive sheet 34.

Further, the light source 31 may be a bullet type (lead frame type) LED in addition to the surface mount type LED. Further, the light source 31 may be an incandescent light bulb, a planar light source such as an EL (Electro-Luminescence) panel, a point light source such as a filament valve, or a linear light source such as a fluorescent display tube, or a combination thereof. May be good.

10 Vehicle 11 Vehicle cabin 12 Dashboard 13 Windshield 20 Head-up display 21 Display device (projector)
22 Reflector 23 Lighting device 24 Storage box 25 Transmitters 31, 31a, 31b Light source (LED)
32 Lens array 33 Circuit board 33a Mounting surface 33b Back side 34 Heat conduction sheet 35 Heat sink 36 Case 36a Anode terminal 36b Cathode terminal 37 Wiring 38a Anode electrode 38b Cathode electrode 41 Base 41a Board side 41b Heat dissipation part Side 42 Heat dissipation part 43 Frame part 43a Tip Surface 44 First heat sink 44a Tip 45 Second heat sink 45a Tip 46 Third heat sink 48, 49 Intersection 51 Screw member 52 Insert nut Ld Display light Vi imaginary image

Claims (4)

A circuit board on which an LED and wiring connected to the LED are mounted,
A base having one surface on which the circuit board is arranged and the other surface which is the opposite surface of the one surface, a plurality of first heat radiation fins protruding from the other surface, and projecting from the other surface. It comprises a plurality of second radiating fins that intersect and form intersections with each of the first radiating fins, and a heat sink formed of a high thermal conductive resin material.
The head-up display is formed at a position where the intersection overlaps with the wiring via the base. The head-up display according to claim 1, wherein the wiring is wider than the LED and is formed so as to spread in the surface direction of the circuit board. The LED is a surface mount type LED and is
The head-up display according to claim 2, wherein the wiring located at a position overlapping the intersection is connected to the cathode terminal of the LED. The head-up display according to claim 1, further comprising a third heat radiation fin that protrudes from the other surface in a size smaller than that of the first heat radiation fin.

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