JP7447162B2 - Vehicle display device - Google Patents

Description

The present invention relates to a display device for a vehicle.

Some vehicles are equipped with a vehicle display device that displays a virtual image of information provided to a driver inside the vehicle. This vehicle display device is a so-called head-up display device, and includes a plurality of light emitting elements mounted on a board and arranged at intervals, and a display light that projects a display image onto a projected member such as a windshield or combiner. There is a device equipped with a display device that emits light as a light source (for example, see Patent Document 1).

In conventional vehicle display devices, polarizing lenses are arranged to match the size of the display area in order to irradiate the entire display area of the display device with light from a light source. Functionally, a polarized lens has a convexly curved exit surface, but a plurality of convex portions (peaks) are formed to match the plurality of light emitting elements, and the plurality of peaks are curved. Recesses (troughs) are also formed between the peaks, that is, at the boundaries of the peaks.

Japanese Patent Application Publication No. 2018-120807

By the way, in conventional vehicle display devices, the light that enters the polarizing lens from the light source is reflected at the troughs of the polarizing lens, which may cause a loss in the light that passes through the polarizing lens. Therefore, the amount of light that passes through the troughs of the polarizing lens decreases with respect to the amount of light that passes through the troughs, and the brightness changes, so there is room for improvement in terms of visibility of virtual images for drivers.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle display device that can improve the visibility of a virtual image displayed in front of a driver.

In order to achieve the above object, a vehicle display device according to the present invention includes one light source and a display image projected onto a projection member provided in a vehicle, which is emitted as display light by light incident from the light source. a first lens disposed on an optical path between the light source and the display device to deflect incident light from the light source toward the display device; and a second lens disposed between the lens and the display device, the second lens distributing the light deflected by the first lens toward the display device, the first lens directing the light toward the display device. The first lens has an exit surface that emits light, the exit surface of the first lens is formed by one convex curved surface corresponding to one of the light sources, and the second lens is deflected by the first lens. and an exit surface that is curved convexly toward the display device and that outputs the light that is incident and transmitted from the entrance surface, and the exit surface of the second lens The surface is characterized in that it has a plurality of curved microlens surfaces.

According to the vehicle display device according to the present invention, it is possible to improve the visibility of the virtual image displayed in front of the driver.

FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle equipped with a vehicle display device according to an embodiment. FIG. 2 is a schematic diagram showing a schematic configuration of a vehicle display device according to an embodiment. FIG. 3 is a schematic diagram showing a schematic configuration of the backlight unit according to the embodiment. FIG. 4(A) is a schematic diagram showing a schematic configuration of a light source and a first lens constituting a backlight unit, and FIG. 4(B) is a schematic diagram showing an example of arrangement of the light source viewed from the optical axis direction. FIG. 5(A) is a partial perspective view of the curved microlens surface of the second lens constituting the backlight unit, and FIG. 5(B) is a partial front view of the curved microlens surface. FIG. 6(A) is a schematic diagram showing the optical path of the reflected light reflected by the end surface of the second lens, and FIG. 6(B) is a schematic diagram showing the optical path of the reflected light reflected by the end surface of the conventional diffuser lens. . FIG. 7(A) is a schematic diagram showing a schematic configuration example of a conventional vehicle display device, and FIG. 7(B) is a comparative example of a conventional vehicle display device and a vehicle display device to which the present invention is applied. FIG. FIG. 8 is a partial side view showing an example of an aspheric surface applied to the curved surface of a microlens according to a modification of the embodiment. FIG. 9 is a diagram showing an illuminance distribution by a microlens according to a modification of the embodiment.

DESCRIPTION OF EMBODIMENTS Below, embodiments of a vehicle display device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. Furthermore, the components in the embodiments described below include those that can be easily imagined by those skilled in the art, or those that are substantially the same. Furthermore, various omissions, substitutions, and changes may be made to the constituent elements in the embodiments described below without departing from the gist of the invention.

[Embodiment]
As shown in FIG. 1, the vehicle display device 1 is a head-up display device mounted on a vehicle 100 such as an automobile. The vehicle display device 1 is arranged inside the instrument panel 102 in the vehicle 100, and projects a display image onto the windshield 103, which is a projected member. Since the windshield 103 has a semi-transparent property that reflects a part of the incident light and transmits the rest, it displays the display light L emitted from the vehicle display device 1 while transmitting the foreground of the vehicle 100. It is reflected toward driver D's eye point EP as an image. The driver D recognizes the displayed image reflected by the windshield 103 as a virtual image S. The virtual image S is recognized ahead of the windshield 103 with respect to the driver D. As shown in FIG. 2, the vehicle display device 1 of this embodiment includes a housing 2, two reflective mirrors 3, a backlight unit 5, and a control section 7.

The housing 2 is made of, for example, synthetic resin, and is fixed to a vehicle body (not shown). As shown in FIG. 2, the housing 2 accommodates and supports a backlight unit 5, two reflective mirrors 3, and a control unit 7 in an internal space 2b. The housing 2 has an opening 2a that communicates the outside with an internal space 2b. The opening 2a is provided in the housing 2 at a position facing the windshield 103, and is closed with a transparent cover 6. The transparent cover 6 transmits the display light L emitted from the backlight unit 5 and reflected by the two reflection mirrors 3. The display light L transmitted through the transparent cover 6 heads toward the windshield 103.

As shown in FIG. 2, the two reflecting mirrors 3 are arranged on the optical path of the display light L from the backlight unit 5 to the windshield 103, and reflect the display light L emitted from the backlight unit 5 to the windshield 103. reflect towards. The two reflecting mirrors 3 are composed of a plane mirror 8 and a concave mirror 9.

The plane mirror 8 has a flat reflective surface and is disposed at a position facing the backlight unit 5. The plane mirror 8 totally reflects the display light L emitted from the backlight unit 5 toward the concave mirror 9 with its reflective surface.

The concave mirror 9 has a reflective surface formed of a concave curved surface, and is disposed at a position facing the plane mirror 8. The concave mirror 9 totally reflects the display light L reflected by the plane mirror 8 toward the windshield 103 via the transparent cover 6. The concave mirror 9 has a function as, for example, a magnifying mirror. The concave mirror 9 is configured such that the display image represented by the display light L after being reflected by the concave mirror 9 is relatively larger than the display image represented by the display light L before being reflected by the concave mirror 9. The displayed image is enlarged and reflected.

The backlight unit 5 emits a display image projected onto the windshield 103 as display light L. The backlight unit 5 includes a cylindrical housing 10, a display device 11, a light source 12, a light source board 13, a first lens 14, and a second lens 15.

The cylindrical casing 10 is formed into a box shape by, for example, synthetic resin, and supports the display device 11 and the second lens 15 along the optical axis direction. The cylindrical housing 10 is open at both ends in the optical axis direction, one opening is closed by the light source board 13, and the other opening is closed by the display device 11.

The display device 11 emits a display image projected onto the windshield 103 as display light L using light incident from the light source 12 . The display device 11 is a so-called liquid crystal panel, and is made of, for example, a light-transmissive or light-semi-transmissive TFT liquid crystal (Thin Film Transistor Liquid Crystal Display). The display device 11 has a display area 11a including a plurality of pixels. In the display area 11a, a plurality of pixels are arranged in a matrix. The display device 11 displays a display image including numbers, characters, graphics, etc. in response to a control signal from the control unit 7, for example. The display area 11a is an area where a display image is displayed. The display device 11 is disposed on the optical path of the light emitted from the light source 12, and is illuminated from the light source 12 side, so that the display surface on the opposite side to the light source 12 in the optical axis direction emits light.

The light source 12 illuminates the display device 11. The light source 12 is composed of, for example, one light emitting element mounted on a light source substrate 13. The light emitting element is, for example, an LED (Light Emitting Diode). Further, the light source 12 includes one in which a plurality of light emitting elements are centrally mounted on the light source substrate 13 at a position where the optical axis of the first lens 14 passes through, as viewed from the optical axis direction of the first lens 14. In this case, one light source 12 is mounted centrally on the light source board 13 at a position through which the optical axis of the first lens 14 passes, as shown in FIGS. 3, 4A, and 4B, for example. It is composed of three LEDs 16. The three LEDs 16 are arranged in a line on the light source board 13 in a direction perpendicular to the light source direction. The light source 12 is lit by, for example, electric power obtained from a power source mounted on the vehicle 100, such as a battery (not shown). Note that the number of LEDs 16 is not limited to three. Furthermore, the arrangement of the plurality of LEDs 16 is not limited to a single row, and may be arranged in a circular or polygonal shape as long as it can be recognized as one light source.

The light source substrate 13 is formed into a rectangular shape when viewed from the light source direction. The light source board 13 has a plurality of LEDs 16, which are the light sources 12, and a plurality of electronic components mounted on a so-called mounting surface. On the other hand, a heat sink (not shown), for example, is fixed to the surface of the light source board 13 opposite to the mounting surface. Heat generated from the light source 12 is accumulated on the light source substrate 13. The heat sink radiates heat accumulated in the light source board 13 to the outside of the backlight unit 5.

The first lens 14 is arranged on the optical path between the light source 12 and the display device 11 and deflects the light incident from the light source 12 toward the display device 11 . The first lens 14 is arranged between the light source 12 and the second lens 15 on the optical path between the light source 12 and the display device 11, as shown in FIG. The first lens 14 is made of, for example, a high refractive index material such as glass or transparent resin, and functions to refract outward light inward and deflect it to the second lens 15 . The first lens 14 is formed into an elliptical shape when viewed from the optical axis direction, as shown in FIG. 4(B). As shown in FIGS. 3 and 4A, the first lens 14 has an entrance surface 14a into which light emitted from the light source 12 enters, and a light entrance surface 14a that directs the light incident from the entrance surface 14a toward the display device 11. It has an output surface 14b.

The entrance surface 14a of the first lens 14 faces the light source 12 and is a flat surface. The exit surface 14b is a surface opposite to the entrance surface 14a, and faces the second lens 15.

The exit surface 14b of the first lens 14 is formed of one convex curved surface corresponding to one light source 12. When viewed from a direction perpendicular to the optical axis direction, the exit surface 14b does not have the one or more valleys formed on the exit surface of the conventional first lens 40, but instead consists of one peak. be done. As shown in FIGS. 4A and 4B, the conventional first lens 40 has a plurality of peaks on the exit surface for the LEDs 60, which are the plurality of light sources. The exit surface 14b has one peak for one light source 12.

The second lens 15 is disposed between the first lens 14 and the display device 11 on the optical path between the light source 12 and the display device 11, and directs the light deflected by the first lens 14 toward the display device 11. to distribute light. The second lens 15 is made of a material such as glass or transparent resin, and refracts and focuses light toward the display area 11a of the display device 11. The second lens 15 is fixed to the cylindrical housing 10 with screws or the like. The second lens 15 is formed into a rectangular shape when viewed from the optical axis direction, as shown in FIG. 4(B). The second lens 15 is formed with an entrance surface 15a on which the light deflected by the first lens 14 enters , and is curved convexly toward the display device 11 side, and emits the light that enters and passes through the entrance surface 15a. It has an output surface 15b.

The entrance surface 15a of the second lens 15 is a curved surface that faces the first lens 14 and is convex toward the first lens 14 side.

The exit surface 15b of the second lens 15 has a plurality of microlens curved surfaces 20, as shown in FIGS. 5A and 5B. The microlens curved surface 20 is a so-called microlens curved surface, and is, for example, a fly's eye-shaped lens surface. The plurality of microlens curved surfaces 20 are arranged, for example, in a grid pattern along the convexly curved exit surface 15b. As shown in FIGS. 5A and 5B, the plurality of microlens curved surfaces 20 are arranged in the X direction on the exit surface 15b and in the Y direction orthogonal to the X direction. Each microlens curved surface 20 has, for example, a rectangular shape when viewed from the front. The microlens curved surface 20 has a long side with a length x in the X direction, and a short side with a length y (≠x) different from the length x in the Y direction. The plurality of microlens curved surfaces 20 have, for example, the same length x in the X direction and the same length y (≠x) in the Y direction.

The control unit 7 is connected to the backlight unit 5 and controls the backlight unit 5, as shown in FIG. The control unit 7 is composed of, for example, an IC chip mounted on a board, and is driven by electric power obtained from a battery mounted on the vehicle 100.

Next, the virtual image display operation in the vehicle display device 1 will be explained with reference to FIGS. 2 and 3. First, light emitted from the light source 12 enters the first lens 14 through the entrance surface 14a, passes through the interior, and exits from the exit surface 14b. The light emitted from the exit surface 14b is refracted by the first lens 14 and polarized toward the entrance surface 15a of the second lens 15. The light incident on the entrance surface 15a of the second lens 15 passes through the interior and exits from the exit surface 15b. The light emitted from the output surface 15b is refracted by the second lens 15, diffused by the plurality of microlens curved surfaces 20 formed on the output surface 15b, and irradiated toward the display area 11a of the display device 11. The display device 11 emits a display image displayed in the display area 11a as display light L using light that has passed through the inside.

Display light L emitted from the display device 11 of the backlight unit 5 heads toward the plane mirror 8. The plane mirror 8 reflects the display light L incident from the backlight unit 5 toward the concave mirror 9. The concave mirror 9 reflects the display light L incident from the plane mirror 8 toward the windshield 103 via the transparent cover 6 using a concave reflecting surface. Thereby, a display image corresponding to the display light L is projected onto the windshield 103, and a virtual image S is displayed in front of the driver's D's eye point EP.

In the vehicle display device 1 of this embodiment, the output surface 14b of the first lens 14 is formed by one convex curved surface corresponding to one light source 12. Thereby, it is possible to arrange the light source 12 on the optical axis of the first lens 14 or on the optical axis side while ensuring that the entire display area 11a of the display device 11 is irradiated with light. As a result, when one light emitting element is used as one light source, the light source board 13 can be reduced in size to about 50% of the conventional board size, and as a result, the backlight unit 5 and vehicle The display device 1 can be made smaller. In addition, conventionally, multiple light sources are arranged evenly on the light source board for one first lens to expand the display area and equalize the brightness. A light source is disposed in the first lens, and a plurality of peaks are required on the exit surface of the first lens. However, when using not only one light emitting element but also multiple light emitting elements for one light source, it is possible to use one light emitting element by centrally mounting multiple light emitting elements in an area called one light source. As in the case where the first lens has a plurality of peaks, the first lens does not need to have a plurality of peaks, and since there are no valleys, changes in brightness of the virtual image S can be reduced and visibility can be improved.

Further, in the vehicle display device 1, the second lens 15 has a plurality of microlens curved surfaces 20 on the exit surface 15b. Conventionally, in order to irradiate the display area 11a of the display device 11 with light from the light source 12, a diffusion lens is placed on the optical path to diffuse the light, but there is a risk that light loss may occur due to transmission through the diffusion lens. There is. Therefore, by forming a plurality of curved microlens surfaces 20 on the exit surface 15b of the second lens 15, a diffusion lens becomes unnecessary, and it is possible to suppress a decrease in brightness caused by transmitting light through a diffusion lens. As a result, visibility can be improved by at least 10%. Furthermore, since the conventional diffusion lens is an additional component, it is possible to reduce the number of additional components and improve the ease of assembling the device.

Further, in the vehicle display device 1, as shown in FIG. The surface 15a is formed in a convex curve toward the light source 12 side. On the other hand, the conventional diffusing lens 50 shown in FIG. 6(B) is formed such that both the incident surface and the exit surface are curved in a concave shape. Therefore, the area of both end surfaces 15c of the second lens 15 in the direction perpendicular to the optical axis direction can be reduced compared to both end surfaces 50a of the conventional diffusing lens 50. As a result, it is possible to reduce the reflected light La reflected at both end surfaces 15c of the second lens 15, and to suppress the reflected light La traveling toward the windshield 103 through the regular optical path formed between the two light shielding walls 30. Therefore, the visibility of the virtual image S can be improved. In addition, by forming the inclination 15d of the end surface 15c of the second lens 15 so as to be inclined from the outside to the inside, the reflected light La reflected by the end surface 15c is blocked by hitting the light shielding wall 30, and the light path other than the normal optical path is blocked. The visibility of the virtual image S can be improved by reducing the amount of light that passes through it.

Furthermore, since the conventional backlight unit 202 shown in FIG. A part of the light is reflected by the transparent cover 6 and becomes stray light, which is mixed with the display light L through the concave mirror 9, and there is a possibility that the visibility of the virtual image S may be reduced. With the above configuration, the distance between the backlight unit 202 and the concave mirror 9 can be shortened by reducing the reflected light La (FIG. 7(B)). As a result, the housing 2 can be made smaller than the housing 201 of the conventional vehicle display device 200.

In the above embodiment, the microlens curved surface 20 is described as a fly's eye-shaped lens surface. In general, fly-eye lenses include those made of a spherical lens and those made of a cylindrical lens, but the microlens curved surface 20 is not limited to a spherical surface, and may be an aspherical surface, for example. . FIG. 8 is a partial side view of an aspherical surface applied to a curved surface of a microlens according to a modification of the embodiment, and FIG. 9 is a diagram showing the illuminance distribution due to the aspherical microlens. The microlens curved surface 20A according to the modified example of the embodiment is an aspheric surface that diffuses light substantially uniformly so that uneven brightness is suppressed (FIGS. 8 and 9). The shape of the aspherical surface is designed according to the geometric arrangement and shape of the optical system of the device. As long as the shape satisfies the above, the shape of the microlens curved surface 20A viewed from the direction perpendicular to the optical axis direction may be either symmetrical or asymmetrical. Further, as long as the shape satisfies the above, the lens height when the microlens curved surface 20 is an aspherical surface may be higher or lower than the lens height when the microlens curved surface 20 is a spherical surface. Further, as long as it is possible to uniformly diffuse light so that uneven brightness is suppressed throughout the second lens 15, all of the plurality of microlens curved surfaces 20A may be aspherical surfaces having the same shape, The aspheric surfaces may have mutually different shapes. Since the microlens curved surface 20A is an aspherical surface, it can efficiently diffuse the light emitted from the exit surface 15b of the second lens 15 toward the display device 11, and locally concentrate the light. Since light is suppressed, it is possible to suppress unevenness in brightness of a displayed image. As a result, the vehicle display device 1 according to the modification of the present embodiment can improve the visibility of the virtual image S displayed in front of the driver D.

In the above embodiment, the backlight unit 5 is of a liquid crystal type, but may be of another type, such as a laser type, a DLP (Digital Light Processing) type, or a projector type.

Further, in the embodiment described above, the control unit 7 is connected to an ECU (Electronic Control Unit) (not shown) mounted on the vehicle 100, and even if the control unit 7 is transmitting and receiving signals with the ECU, good.

Further, in the embodiment described above, the vehicle display device 1 includes two reflective mirrors 3, but the present invention is not limited to this. For example, the vehicle display device 1A shown in FIG. 7(B) may include one reflective mirror 3 (concave mirror 9). Further, three or more reflecting mirrors 3 may be provided. The plane mirror 8 may be a concave mirror, or may be, for example, a convex mirror, an aspherical mirror, a spherical mirror, a free-form mirror, or the like. The concave mirror 9 may be, for example, a convex mirror, an aspherical mirror, a spherical mirror, a free-form mirror, or the like. Further, the concave mirror 9 has a function as a magnifying mirror, but is not limited to this, and may also have a function as a correction mirror.

Further, in the embodiments described above, the vehicle display devices 1 and 1A project the display image onto the windshield 103 of the vehicle 100, but the display image is not limited to this, and may be projected onto a combiner or the like, for example.

Further, in the above embodiments, the vehicle display devices 1 and 1A are applied to the vehicle 100 such as an automobile, but the present invention is not limited thereto, and may be applied to, for example, a ship or an aircraft other than the vehicle 100.

1 Vehicle display device 5 Backlight unit 11 Display device 12 Light source 13 Light source board 14 First lens 14a, 15a Incident surface 14b, 15b Output surface 15 Second lens 20 Microlens curved surface 100 Vehicle 103 Windshield L Display light S Virtual image

Claims (3)

one light source and
a display device that emits a display image projected onto a projection target member provided in a vehicle as display light using light incident from the light source;
a first lens that is disposed on an optical path between the light source and the display device and deflects light incident from the light source toward the display device;
a second lens disposed on the optical path between the first lens and the display device, and distributing the light deflected by the first lens toward the display device;
The first lens is
having an exit surface that emits light toward the display device,
The exit surface of the first lens is
formed of one convex curved surface corresponding to one of the light sources,
The second lens is
an entrance surface on which the light deflected by the first lens enters;
an output surface that is curved in a convex shape toward the display device and that outputs light that has entered and passed through the input surface;
The exit surface of the second lens is
Having a plurality of curved microlens surfaces,
A vehicle display device characterized by: The entrance surface of the second lens is
Curved convexly toward the light source side,
The vehicle display device according to claim 1. The microlens curved surface is
It is aspherical,
The vehicle display device according to claim 1 or 2.

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