JP6876252B2 - Backlight unit and head-up display - Google Patents

Description

The present invention relates to a backlight unit and a head-up display including the backlight unit.

The head-up display is mounted on a vehicle, for example, and displays information necessary for driving to the driver as a virtual image through a transmission reflection unit such as a windshield. As a result, the head-up display can display information by superimposing it on the scenery in front of the vehicle, and the driver can grasp necessary information without making a large movement of the line of sight during driving.

The head-up display has a display device for displaying a display image. This display device includes a liquid crystal display panel and a backlight unit for illuminating the liquid crystal panel. The backlight unit has a substrate on which a light source is mounted and a lens that collects light from the light source. Further, since the backlight unit has a heat sink and a heat conductive sheet, the heat generated by the light source is dissipated to the outside.

JP-A-2009-255851

The lens is designed to efficiently collect the light from the light source. Therefore, the lens and the substrate must be positioned accurately.

Here, the backlight unit is manufactured by sequentially assembling a lens, a substrate, a heat conductive sheet, and a heat sink. For example, in order to accurately position each component by using the positioning pin and the corresponding hole, it is necessary to reduce the clearance between the positioning pin and the hole. On the other hand, in order to improve workability at the time of assembly, it is better that the clearance is large. Therefore, it has been an issue to achieve both positioning accuracy and workability.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a backlight unit having excellent manufacturability and a head-up display provided with the backlight unit.

In the backlight unit according to the present invention, in order to solve the above-mentioned problems, a substrate on which a light source is mounted and having a first positioning hole, and a heat sink that dissipates heat from the light source and has a second positioning hole. A lens having a positioning pin that collects light rays from the light source and is sequentially inserted into the first positioning hole and the second positioning hole, and the positioning pin includes a thick pin portion and the said positioning pin. It has a thin pin portion thinner than the thick pin portion and a tapered portion connecting the thick pin portion and the thin pin portion, and has the thin pin portion, the tapered portion, and the thick pin portion in order from the tip side. The second positioning hole has a thick hole portion and a narrow hole portion thinner than the thick hole portion, and the lens has the substrate by inserting the thick pin portion into the first positioning hole. It is positioned with respect to the heat sink, and the fine pin portion is inserted into the fine hole portion to be positioned with respect to the heat sink.

In the backlight unit and the head-up display according to the present invention, the manufacturability can be improved.

It is an embodiment of the head-up display which concerns on this invention, and is the perspective view explaining the whole structure. Top view of the head-up display with the upper case and the translucent cover removed. The vertical sectional view of the head-up display of FIG. An exploded perspective view of the backlight unit. FIG. 5 is a cross-sectional view for explaining the positioning of the backlight unit. A rear-view perspective view for explaining the lens.

An embodiment of the head-up display according to the present invention will be described with reference to the accompanying drawings. The head-up display according to the present invention is mounted on a vehicle such as an automobile. In the present embodiment, an example in which the head-up display according to the present invention is mounted on an automobile will be described.

FIG. 1 is an embodiment of a head-up display according to the present invention, and is a perspective view illustrating an overall configuration.

FIG. 2 is a plan view of the head-up display 1 with the upper case 21 and the translucent cover 30 removed.

FIG. 3 is a vertical cross-sectional view of the head-up display 1 of FIG.

The head-up display 1 (hereinafter referred to as HUD1) is arranged in the instrument panel of the automobile. The HUD 1 mainly includes a display device 3, a plane mirror 4, a concave mirror 5, a case 6, and a control board 7. The HUD 1 reflects the display light representing the display image displayed by the display device 3 by the plane mirror 4 and the concave mirror 5 constituting the relay optical system, and irradiates the windshield of an automobile, which is an example of the transmission reflection unit. The viewer (mainly the driver) can visually recognize the virtual image of the displayed image by superimposing it on the actual view in front of the vehicle.

The display device 3 outputs the display light. The display device 3 is, for example, a TFT (Thin Film Transistor) type liquid crystal display device. The display device 3 has a backlight unit 40 and a liquid crystal display panel 41 that receives the light from the backlight unit 40 and emits the display light. Although detailed illustration thereof is omitted here, the liquid crystal display panel 41 is The backlight unit 40 is located on the plane mirror 4 side, and the backlight unit 40 is located on the heat sink side, which will be described later.

FIG. 4 is an exploded perspective view of the backlight unit 40. The backlight unit 40 includes a light source substrate 50, a lens 51, a lens case 52, a heat sink 53, and a heat conductive sheet 54. The light source 56 is mounted on the light source substrate 50. The light source 56 is composed of a light emitting element such as an LED (Light Emitting Diode) and emits a light ray. The light source substrate 50 is, for example, an alumina (ceramics) substrate having excellent thermal conductivity. The lens 51 collects the light rays emitted from the light source 56 and makes them parallel to the optical axis of the HUD1. The lens 51 associates one lens unit 51a with one light source 56. That is, when a plurality of light sources 56 are used, the lens 51 has a plurality of lens portions 51a. The lens case 52 is a tubular case made of a non-transparent resin material. The lens case 52 accommodates the light source substrate 50 and the lens 51. Further, the lens case 52 guides the parallel light emitted from the lens 51 to the liquid crystal display panel 41. The heat sink 53 is provided in the opening 28 of the case 6. The heat sink 53 is made of a metal such as aluminum. The heat sink 53 releases the heat generated by the light source 56 at the fins 53a into the air. The heat conductive sheet 54 is provided between the light source substrate 50 and the heat sink 53, and efficiently transfers the heat of the light source 56 to the heat sink 53.

The liquid crystal display panel 41 (FIG. 2) has a liquid crystal cell and a polarizing plate. The liquid crystal cell has a pair of translucent substrates on which a transparent electrode film is formed, and a liquid crystal layer enclosed in the translucent substrate. Polarizing plates are attached to both front and rear surfaces of the liquid crystal cell. The light rays that have become parallel light from the lens 51 pass through the liquid crystal display panel 41 and are output as display light.

The plane mirror 4 (reflecting mirror) has, for example, a base material made of a synthetic resin material and a reflective film formed on the surface of the base material by vapor deposition or the like. The plane mirror 4 reflects the display light output from the display device 3 toward the concave mirror 5.

The concave mirror 5 (reflecting mirror) has, for example, a base material made of a synthetic resin material and a reflective film formed on the surface of the base material by means such as thin film deposition. The concave mirror 5 reflects the display light reflected by the plane mirror 4 toward the windshield. The concave mirror 5 has a function as a magnifying glass, magnifies the displayed image, and reflects it on the windshield. As a result, the viewer visually recognizes a virtual image in which the displayed image is enlarged. Further, the concave mirror 5 corrects the distortion of the display light due to the curved surface of the windshield with the concave curved surface. The concave mirror 5 is rotated around a rotation axis (not shown) by an actuator. The actuator adjusts the angle of the concave mirror 5 by rotating the concave mirror 5 to adjust the irradiation position of the display light, or adjusts the angle so that the external light is not reflected by the concave mirror 5 toward the display device 3.

The case 6 (FIG. 1) is formed of, for example, a black synthetic resin having a light-shielding property, and has an upper case 21 and a lower case 22. The case 6 has an internal space 23 for accommodating the display device 3, the plane mirror 4, and the concave mirror 5 by combining the upper case 21 and the lower case 22. The upper case 21 has an opening 27. The opening 27 is provided in a portion facing the windshield. The opening 27 is covered with a translucent cover 30 having translucency. The lower case 22 has a structure for mainly attaching the display device 3, the plane mirror 4, the concave mirror 5, and the control board 7.

The control board 7 is a printed circuit board on which a control unit (not shown) that controls the operation of the display device 3 or the like is mounted. The control unit has, for example, a microcomputer having a storage device and an arithmetic unit. The control unit causes the display device 3 to display the display image by appropriately calculating the display image according to the operation program stored in advance by the storage device based on the various vehicle information acquired from the in-vehicle network and various sensors. The control board 7 is fixed to the lower case 22 together with the board cover 31 on the outer surface 29 outside the internal space 23 of the lower case 22.

Hereinafter, the assembly of the backlight unit 40 will be described in detail.

FIG. 5 is a cross-sectional view for explaining the positioning of the backlight unit 40.

FIG. 6 is a perspective view seen from the back surface for explaining the lens 51.

In the backlight unit 40, after the lens 51, the light source substrate 50, and the heat conductive sheet 54 are positioned and fixed to the heat sink 53, the lens case 52 covers the lens 51, the light source substrate 50, and the heat conductive sheet 54 on the heat sink 53. It is assembled as one unit by being fixed with screws.

The lens 51, the light source substrate 50, the heat conductive sheet 54, and the heat sink 53 have a structure for positioning. Specifically, the light source substrate 50 has a first positioning hole 60 (hereinafter, simply referred to as “board hole 60”). The hole 60 of the substrate penetrates the light source substrate 50. The heat sink 53 has a second positioning hole 61 (hereinafter, simply referred to as “heat sink hole 61”). The hole 61 of the heat sink has a thick hole portion 61a and a narrow hole portion 61b in this order from the opening side (FIG. 5). The heat conductive sheet 54 has a third positioning hole 62 (hereinafter, simply referred to as “sheet hole 62”). The hole 62 of the sheet penetrates the heat conductive sheet 54. In the present embodiment, the hole 60 of the substrate, the hole 61 of the heat sink, and the hole 62 of the sheet are circular. Further, the hole 62 and the thick hole 61a of the sheet are larger than the hole 60 of the substrate in consideration of workability at the time of assembly.

The lens 51 has a positioning pin 65 having a circular cross section, which is arranged on substantially the same axis as the center of the hole 60 of the substrate, the hole 61 of the heat sink, and the hole 62 of the sheet. The positioning pin 65 has a thick pin portion 65a, a thin pin portion 65b, and a tapered portion 65c. The thick pin portion 65a is provided on the root side of the positioning pin 65. The thin pin portion 65b is thinner than the thick pin portion 65a and is provided on the tip end side of the positioning pin 65. The tapered portion 65c connects the thick pin portion 65a and the thin pin portion 65b. That is, the positioning pin 65 has a thin pin portion 65b, a tapered portion 65c, and a thick pin portion 65a in this order from the tip end side of the positioning pin 65. The fine pin portion 65b fits the fine hole portion 61b of the hole 61 of the heat sink to determine the position of the heat sink 53 and the lens 51. The thick pin portion 65a positions the lens 51 and the light source substrate 50 by fitting into the hole 60 of the substrate. Further, the thick hole portion 61a is larger (thicker) than the hole 60 (thick pin portion 65a) of the substrate.

The backlight unit 40 having such a positioning configuration is positioned as follows.

First, the heat conductive sheet 54 and the light source substrate 50 are sequentially arranged on the heat sink 53. The heat sink 53 is provided with a positioning wall 53b (FIG. 4). The heat conductive sheet 54 and the light source substrate 50 are arranged so as to be aligned with the positioning wall 53b.

Next, the positioning pin 65 of the lens 51 penetrates the hole 60 of the substrate and the hole 62 of the sheet, and is inserted into the hole 61 of the heat sink. The holes 62 and the thick holes 61a of the sheet are larger than the holes 60 of the substrate. Therefore, when the positioning pin 65 is inserted, the light source substrate 50 displaced from the correct position hides the hole 62 and the thick hole 61a of the sheet, so that the insertion of the positioning pin 65 is not hindered.

Here, due to the accuracy of positioning the heat sink 53 and the light source substrate 50, the hole 60 of the substrate may be displaced with respect to the hole 61 of the heat sink when the positioning pin 65 is inserted. On the other hand, the positioning pin 65 is inserted into the hole 61 of the heat sink, the fine pin portion 65b is inserted into the fine hole portion 61b and fitted, and the lens 51 and the heat sink 53 are correctly positioned. At the same time, the tapered portion 65c located in the hole 60 of the substrate slides the light source substrate 50 to guide it to the correct position. As a result, the thick pin portion 65a is inserted into the hole 60 of the substrate and fitted into the hole 60, and the lens 51 and the light source substrate 50 are correctly positioned. That is, by inserting the positioning pin 65 into the hole 61 of the heat sink, the positions of the light source substrate 50 and the lens 51 are determined, and at the same time, the positions of the lens 51 and the heat sink 53 are determined.

The backlight unit 40 and the HUD1 in the present embodiment can improve the manufacturability by improving the workability at the time of assembling the backlight unit 40. That is, in order to collect and parallelize the light rays of the light source 56 as designed, the lens 51 and the light source substrate 50 must be accurately positioned. In the backlight unit 40 and HUD1 of the present embodiment, the positioning pin 65 of the lens 51 has a tapered portion 65c that connects the thick pin portion 65a and the thin pin portion 65b. Therefore, even if the light source substrate 50 on the heat sink 53 and the heat conductive sheet 54 are displaced from their original positions during assembly, the tapered portion 65c acts to position the lens 51 on the heat sink 53 at the same time. , The lens 51 can be correctly positioned on the light source substrate 50. Therefore, it is not necessary to separately perform the work for positioning the lens 51 and the light source substrate 50.

Further, when there is no tapered portion 65c, that is, when there is a step at the connection point between the thick pin portion 65a and the thin pin portion 65b, the light source substrate 50 is displaced with respect to the heat sink 53, and as a result, the light source substrate 50 (heat) of the heat sink 53 is used. Conduction sheet 54) It is conceivable that this step is caught on the installation surface and the positioning pin 65 is not correctly inserted into the heat sink 53. If the assembling worker does not notice this and attaches the lens case 52, which is the next process, the light rays may not be properly collected and parallelized by the lens 51, and the displayed image may not be displayed in its original performance. is there. On the other hand, in the backlight unit 40 and the HUD1 in the present embodiment, as described above, the lens 51 can be attached to the correct position, so that the above problem can be prevented from occurring.

Although some embodiments of the present invention have been described, 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 heat conductive sheet 54 may be omitted.

1 Head-up display (HUD)
3 Display device 4 Plane mirror 5 Concave mirror 6 Case 7 Control board 21 Upper case 22 Lower case 30 Translucent cover 40 Backlight unit 41 Liquid crystal display panel 50 Light source board 51 Lens 52 Lens case 53 Heat sink 54 Heat conduction sheet 56 Light source 60 First Positioning hole (hole on the board)
61 Second positioning hole (heat sink hole)
61a Thick hole 61b Fine hole 62 Third positioning hole (seat hole)
65 Positioning pin 65a Thick pin 65b Thin pin 65c Tapered

Claims (3)

A substrate on which a light source is mounted and having a first positioning hole,
A heat sink that dissipates heat from the light source and has a second positioning hole,
A lens having a positioning pin that collects light rays from the light source and is sequentially inserted into the first positioning hole and the second positioning hole is provided.
The positioning pin has a thick pin portion, a thin pin portion thinner than the thick pin portion, and a tapered portion connecting the thick pin portion and the thin pin portion, and the thin pin portion, the tapered portion, and the tapered portion. The thick pin portion is held in order from the tip side,
The second positioning hole has a thick hole portion and a narrow hole portion thinner than the thick hole portion.
The lens is positioned with respect to the substrate by inserting the thick pin portion into the first positioning hole, and is positioned with respect to the heat sink by inserting the fine pin portion into the fine hole portion. A backlight unit characterized by being used. The backlight unit according to claim 1, wherein the thick hole portion is thicker than the first positioning hole. A display device having the backlight unit and a liquid crystal display panel according to claim 1 and outputting display light,
It has a reflecting mirror that reflects the display light.
A head-up display characterized by irradiating a transmitted reflecting portion with the display light reflected by the reflecting mirror.

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