Vehicle display device

Abstract

To display a high-brightness virtual image while keeping the backlight unit size down. [Solution] The invention comprises a light-transmitting display unit 10, a backlight unit 20 that projects light onto the back surface 10a of the display unit and emits display information as display light from the front surface 10b of the display unit, at least one reflective member 40 that reflects the display light emitted from the display unit and projects this display light onto the projection unit Rwf, and an external housing 51 that houses these components. The backlight unit comprises a light source 21, a Fresnel lens 22 that causes the light emitted from the light source to enter from an incident surface 22a and emit it from an exit surface 22b as parallel light perpendicular to the exit surface, and a microlens 23 that causes the parallel light to enter from an incident surface 23a and emits it from an exit surface 23b as diffuse light toward the back surface of the display unit. The Fresnel lens and the microlens are arranged with the exit surface 22b and incident surface 23a facing each other.

Description

Technical Field

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[0001] The present invention relates to a vehicle display device.

Background Art

[0002] Conventionally, vehicles have been equipped with a vehicle display device that displays virtual images of information provided to passengers inside the vehicle. This vehicle display device is a so-called head-up display device, and includes a light-transmissive display that displays display information to be projected onto a projection target, a backlight unit that projects light onto the back of the display and emits the display information as display light from the front of the display, a reflection member that reflects the display light emitted from the display and projects the display light onto the projection target, and an external housing that houses these components. This vehicle display device projects the display light reflected by the reflection member onto the projection target outside the external housing, and allows the passenger to visually recognize the display information corresponding to the projected display light as a virtual image. This type of vehicle display device is disclosed in, for example, Patent Document 1 below.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a vehicle display device, in order to display a high-brightness virtual image, a lens member for distributing the emitted light from the light source over the entire back surface of the display is provided in the backlight unit. For example, in a conventional backlight unit, the incident light is bent, such as by using a lens member with an increased thickness, to distribute the emitted light from the lens member over a wide range. However, such a conventional vehicle display device may cause the backlight unit to increase in size, at least in the thickness direction of the lens member.

[0005] Therefore, the object of the present invention is to provide a vehicle display device that can display a high-brightness virtual image while suppressing the increase in size of the backlight unit. [Means for solving the problem]

[0006] The present invention comprises a light-transmitting display that displays display information to be perceived as a virtual image by an occupant in a vehicle cabin; a backlight unit that projects light onto the back of the display and emits the display information as display light from the front of the display; at least one reflective member that reflects the display light emitted from the display and projects this display light onto the projection area; and an external housing that houses the display, the backlight unit, and the reflective member, wherein the backlight unit comprises a light source; a Fresnel lens that causes the emitted light from the light source to be incident from an incident surface and emits it from an exit surface as parallel light perpendicular to the exit surface; and a microlens that causes the parallel light to be incident from an incident surface and emits it from an exit surface as diffuse light toward the back of the display, wherein the Fresnel lens and the microlens are arranged so that the exit surface of the Fresnel lens and the incident surface of the microlens face each other. [Effects of the Invention]

[0007] The backlight unit of the vehicle display device according to the present invention can distribute the light emitted from the light source over a wide area toward the back of the display by stacking a Fresnel lens and a microlens, without using a thick lens member as in the conventional invention. In other words, this backlight unit can stack a Fresnel lens and a microlens at a narrower spacing than the thickness of a conventional lens member, without using a thick lens member as in the conventional invention, thus achieving high light distribution functionality while suppressing an increase in the size of the lens configuration. Therefore, the vehicle display device according to the present invention can display a high-brightness virtual image while suppressing an increase in the size of the backlight unit. [Brief explanation of the drawing]

[0008] [Figure 1]Figure 1 is a schematic diagram showing a vehicle display device according to an embodiment. [Figure 2] Figure 2 is a perspective view showing the backlight unit of an embodiment. [Figure 3] Figure 3 is a perspective cross-sectional view illustrating the main internal components of the backlight unit according to the embodiment. [Figure 4] Figure 4 is an exploded perspective view illustrating the main internal components of the backlight unit of the embodiment. [Figure 5] Figure 5 is an exploded perspective view illustrating Fresnel lenses and microlenses. [Figure 6] Figure 6 is an explanatory diagram illustrating the optical path of the backlight unit. [Modes for carrying out the invention]

[0009] Embodiments of the vehicle display device according to the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to these embodiments.

[0010] [Embodiment] One embodiment of the vehicle display device according to the present invention will be described with reference to Figures 1 to 6.

[0011] Reference numeral 1 in Figures 1 to 4 indicates a vehicle display device of this embodiment. This vehicle display device 1 is a so-called head-up display device that displays virtual images of information to be provided to occupants inside a vehicle (such as an automobile).

[0012] The vehicle display device 1 includes a light-transmitting, plate-shaped display unit 10 that displays information to be seen as a virtual image by occupants inside the vehicle, and a backlight unit 20 that projects light onto the back surface 10a of the display unit 10 and emits the display information as display light from the front surface 10b of the display unit 10 (Figures 1 to 4). The vehicle display device 1 also includes a control unit 30 that controls the display unit 10 and the backlight unit 20 (Figure 1).

[0013] Furthermore, the vehicle display device 1 includes at least one reflective member 40 that reflects the display light emitted from the display unit 10 and projects this display light onto the projection area Rwf (Figure 1). The vehicle display device 1 reflects the display light at its projection area Rwf toward the occupant's eye point EP or eye box EB. The eye point EP indicates the position of the occupant's eyes inside the vehicle. The eye box EB indicates the range of the eye point EP from which the virtual image can be seen.

[0014] Here, the projected portion Rwf refers to the windshield (in this case, the front windshield Wf) itself or a part thereof. The projected portion Rwf may also be formed as a half-mirror that receives the display light from the reflective member 40 on its reflective surface and reflects it to the occupant's eye point EP or eye box EB, and also emits light from outside the vehicle towards the occupant. For example, the projected portion Rwf as a half-mirror may be formed as a semi-transparent film conforming to the curved shape of the windshield (front windshield Wf) and attached to the interior wall surface of this windshield with adhesive. Alternatively, the projected portion Rwf as a half-mirror may be formed as a semi-transparent film conforming to the curved shape of the windshield (front windshield Wf) and sealed together with an interlayer within a laminated glass windshield. Furthermore, the projected portion Rwf as a half-mirror may be a semi-transparent coating applied to the interior wall surface of the windshield (front windshield Wf) by coating or the like. Furthermore, the projection area Rwf may be a combiner that covers the front windshield Wf from the inside of the vehicle.

[0015] The vehicle display device 1 comprises an external housing 51 that houses a display unit 10, a backlight unit 20, and a reflective member 40, and a transparent cover 52 that closes the opening 51a of the external housing 51 (Figure 1). The vehicle display device 1 shown here is housed inside the instrument panel Pi in the vehicle interior with its cover 52 exposed.

[0016] As the display 10, for example, a transmissive TFT liquid crystal (Thin Film Transistor Liquid Crystal Display) or the like is used. This display 10 displays, for example, image information such as characters, numbers, and figures as display information. The control unit 30 controls this display 10 to perform display control of the display information.

[0017] As the reflection member 40, a first reflection member 40A that reflects the display light emitted from the display 10 and a second reflection member 40B that reflects the reflected light reflected by the first reflection member 40A are provided (FIG. 1). For the first reflection member 40A, for example, a plane mirror or a concave mirror is used. In this example, a plane mirror is used for the first reflection member 40A. Also, for the second reflection member 40B, for example, a concave mirror is used. In the vehicle display device 1, the display light emitted from the display 10 is reflected by the first reflection member 40A toward the second reflection member 40B, and the display light is reflected by the second reflection member 40B after being enlarged. The second reflection member 40B emits the enlarged and reflected display light outside the external housing 51 from the cover 52 and projects it onto the projection target portion Rwf existing ahead (FIG. 1).

[0018] The backlight unit 20 includes a light source 21, a Fresnel lens 22 that makes the light emitted from this light source 21 enter from an incident surface 22a and emits it as parallel light orthogonal to the emission surface 22b from the emission surface 22b, and a microlens 23 that makes the parallel light enter from an incident surface 23a and emits it as diffused light from an emission surface 23b toward the back surface 10a of the display 10 (FIGS. 2 to 6). For example, the light source 21 shown here is a light-emitting element, and a light-emitting diode element is used. The backlight unit 20 includes an internal housing 25 that houses the light source 21, the Fresnel lens 22, and the microlens 23 and holds the display 10 (FIGS. 2 to 4).

[0019] The Fresnel lens 22 has a Fresnel lens body 22c provided with an incident surface 22a and an exit surface 22b (Figs. 4 to 6). The Fresnel lens body 22c is formed, for example, in a rectangular flat plate shape. In this Fresnel lens body 22c, the exit surface 22b is formed in a sawtooth shape that emits parallel light orthogonal to the exit surface 22b.

[0020] The microlens 23 has a microlens body 23c provided with an incident surface 23a and an exit surface 23b (Figs. 4 to 6). The microlens body 23c is formed, for example, in a rectangular flat plate shape. In this microlens body 23c, a plurality of convex portions for diffusing and emitting incident light are provided on the exit surface 23b.

[0021] The Fresnel lens 22 and the microlens 23 are arranged with the exit surface 22b of the Fresnel lens 22 facing the incident surface 23a of the microlens 23. The backlight unit 20 can distribute the light emitted from the light source 21 over a wide range toward the back surface 10a of the display 10 by arranging the thin Fresnel lens 22 and the thin microlens 23 in an overlapping manner at an interval narrower than the thickness of the conventional lens member without using a thick lens member as in the prior art.

[0022] Here, in this backlight unit 20, a gap G is provided between the exit surface 22b of the Fresnel lens 22 and the incident surface 23a of the microlens 23 (Fig. 6). Thereby, in this backlight unit 20, it becomes possible to suppress deformation such as the sawtooth shape on the exit surface 22b of the Fresnel lens 22, and the exit surface 22b can be protected. The backlight unit 20 is configured as follows to maintain the gap G.

[0023] The Fresnel lens 22 has a first support portion 22d that protrudes from the Fresnel lens body 22c on the same plane as the incident surface 22a and the exit surface 22b of the Fresnel lens body 22c, and a second support portion 22e that protrudes from the Fresnel lens body 22c on the same plane as the incident surface 22a and the exit surface 22b of the Fresnel lens body 22c (Figures 4 and 5). The microlens 23 has a first opposing portion 23d that protrudes from the microlens body 23c on the same plane as the incident surface 23a and the exit surface 23b of the microlens body 23c and abuts against the first support portion 22d, and a second opposing portion 23e that protrudes from the microlens body 23c on the same plane as the incident surface 23a and the exit surface 23b of the microlens body 23c and abuts against the second support portion 22e (Figures 4 and 5).

[0024] The first support portion 22d and the second support portion 22e shown here are each formed in the shape of a rectangular flat plate. These first support portion 22d and the second support portion 22e protrude in opposite directions relative to the Fresnel lens body 22c. Similarly, the first opposing portion 23d and the second opposing portion 23e shown here are each formed in the shape of a rectangular flat plate. These first opposing portion 23d and the second opposing portion 23e protrude in opposite directions relative to the microlens body 23c.

[0025] Furthermore, the first support portion 22d is provided with a first base portion 22f that protrudes from the wall surface on the exit surface 22b side of the Fresnel lens body 22c toward the first opposing portion 23d (Figure 5). The second support portion 22e is provided with a second base portion 22g that protrudes from the wall surface on the exit surface 22b side of the Fresnel lens body 22c toward the second opposing portion 23e (Figure 5). The first opposing portion 23d is provided with a first mounting portion 23f that protrudes from the wall surface on the incident surface 23a side of the microlens body 23c toward the first base portion 22f and is placed on the first base portion 22f (Figure 5). The second opposing portion 23e is provided with a second mounting portion 23g that protrudes from the wall surface on the incident surface 23a side of the microlens body 23c toward the second base portion 22g and is placed on the second base portion 22g (Figure 5).

[0026] The first base portion 22f and the second base portion 22g shown here are each formed in the shape of a rectangular flat plate. The first base portion 22f and the second base portion 22g are positioned at the tip of their respective protruding directions. The first mounting portion 23f and the second mounting portion 23g shown here are each formed in the shape of a rectangular flat plate. The first mounting portion 23f and the second mounting portion 23g are positioned at the tip of their respective protruding directions.

[0027] The Fresnel lens 22 and the microlens 23 are provided with a gap G between the emission surface 22b of the Fresnel lens body 22c and the incidence surface 23a of the microlens body 23c by placing the first mounting portion 23f on the first base portion 22f and the second mounting portion 23g on the second base portion 22g of the Fresnel lens 22 and the second mounting portion 23g on the second base portion 22g of the Fresnel lens 22 and the microlens 23, respectively. In this way, the backlight unit 20 can contribute to making the Fresnel lens 22 and the microlens 23 thinner compared to when they are provided on only one of the Fresnel lens 22 or the microlens 23.

[0028] To maintain the relative position of the Fresnel lens 22 and the microlens 23, a positioning pin 25a provided in the internal housing 25 is used (Figure 4). Therefore, the first support portion 22d is provided with a through hole 22h for positioning the Fresnel lens 22 relative to the internal housing 25 by inserting the positioning pin 25a (Figure 5). The first opposing portion 23d is provided with a through hole 23h for positioning the microlens 23 relative to the Fresnel lens 22 by inserting the positioning pin 25a (Figures 4 and 5). Here, the through hole 22h is passed through the first base portion 22f, and the through hole 23h is passed through the first installation portion 23f, thereby regulating the relative positions of the first base portion 22f and the first installation portion 23f, and thus maintaining the aforementioned gap G.

[0029] Furthermore, in order to maintain the relative position of the Fresnel lens 22 and the microlens 23, a pair of positioning protrusions 25b provided on the internal housing 25 are used in addition to the positioning pin 25a (Figure 4). Therefore, the Fresnel lens body 22c is provided with a notch 22i into which the positioning protrusion 25b is inserted, for each positioning protrusion 25b (Figures 4 and 5). Similarly, the microlens body 23c is provided with a notch 23i into which the positioning protrusion 25b is inserted, for each positioning protrusion 25b (Figures 4 and 5).

[0030] Specifically, the internal housing 25 shown here comprises a housing member 25A and a cover member 25B (Figures 2 to 4). In the housing member 25A, the light source 21 is housed inside, and a Fresnel lens 22 and a microlens 23 are installed in the opening 25c (Figure 4). Positioning pins 25a and a pair of positioning protrusions 25b are provided on the periphery of the opening 25c (Figure 4). The cover member 25B covers the Fresnel lens 22 and microlens 23 together with the opening 25c of the housing member 25A when assembled to the housing member 25A. The display unit 10 is held by the cover member 25B with its front surface 10b exposed.

[0031] As described above, the backlight unit 20 of this embodiment can distribute the light emitted from the light source 21 over a wide area toward the back surface 10a of the display unit 10 without using a thick lens member like in the conventional model. In other words, the backlight unit 20 of this embodiment can arrange the Fresnel lens 22 and microlens 23 on top of each other at a narrower spacing than the thickness of a conventional lens member, without using a thick lens member like in the conventional model. Therefore, it is possible to obtain high light distribution functionality while suppressing an increase in the size of the lens configuration. Thus, the vehicle display device 1 of this embodiment can display a high-brightness virtual image while suppressing an increase in the size of the backlight unit 20.

[0032] Furthermore, the backlight unit 20 of this embodiment does not require the adjustment of the light distribution range by changing the thickness of the lens member as in the conventional method; the light distribution range can be adjusted simply by changing the sawtooth shape of the Fresnel lens 22. Therefore, the vehicle display device 1 of this embodiment offers excellent design flexibility for the backlight unit 20 when adjusting the light distribution range, and can flexibly accommodate even if the display unit 10 becomes larger. [Explanation of symbols]

[0033] 1. Vehicle display device 10 Display 10a back 10b front 20 backlight units 21 Light source 22 Fresnel lens 22a Incidence plane 22b Output surface 22c Fresnel lens body 22d 1st support part 22e 2nd support part 22f First base section 22g Second base 22h through hole 23 Microlenses 23a Incidence plane 23b Output surface 23c Microlens Body 23d 1st opposing part 23e Second opposing section 23f 1st installation section 23g 2nd installation part 23h through hole 25 Internal enclosure 25a Positioning pin 40 Reflective material 40A First reflective member 40B Second reflective member 51 External enclosure G gap Rwf Projection area

Claims

1. A light-transmitting display that shows information to be perceived as a virtual image by the occupants inside the vehicle, A backlight unit that projects light onto the back of the display and emits the display information as display light from the front of the display, At least one reflective member that reflects the display light emitted from the display and projects this display light onto the projection area, The external housing comprises the display unit, the backlight unit, and the reflective member, Equipped with, The backlight unit comprises a light source, a Fresnel lens that causes the light emitted from the light source to enter from an incident surface and emit it from an exit surface as parallel light perpendicular to the exit surface, and a microlens that causes the parallel light to enter from an incident surface and emit it from an exit surface as diffused light toward the back surface of the display, A vehicle display device characterized in that the Fresnel lens and the microlens are arranged so that the exit surface of the Fresnel lens and the incident surface of the microlens face each other.

2. The vehicle display device according to claim 1, characterized in that a gap is provided between the exit surface of the Fresnel lens and the incident surface of the microlens.

3. The Fresnel lens comprises a Fresnel lens body having its own incident surface and exit surface, a first support portion protruding from the Fresnel lens body on the same plane as the incident surface and exit surface of the Fresnel lens body, and a second support portion protruding from the Fresnel lens body on the same plane as the incident surface and exit surface of the Fresnel lens body. The microlens comprises a microlens body having its own incident surface and exit surface, a first opposing portion that protrudes from the microlens body on the same plane as the incident surface and exit surface of the microlens body and abuts against the first support portion, and a second opposing portion that protrudes from the microlens body on the same plane as the incident surface and exit surface of the microlens body and abuts against the second support portion, The first support portion is provided with a first base portion that protrudes from the wall surface on the emission side of the Fresnel lens body toward the first opposing portion, The second support portion is provided with a second base portion that protrudes from the wall surface on the emission side of the Fresnel lens body toward the second opposing portion, The first opposing portion is provided with a first mounting portion that protrudes from the wall surface on the incident surface side of the microlens body toward the first base portion and is placed on the first base portion. The second opposing portion is provided with a second mounting portion that protrudes from the wall surface on the incident surface side of the microlens body toward the second base portion and is placed on the second base portion. The vehicle display device according to claim 2, characterized in that the Fresnel lens and the microlens are provided with a gap between the exit surface of the Fresnel lens body and the incident surface of the microlens body by placing the first mounting portion on the first base portion and the second mounting portion on the second base portion.

4. The backlight unit comprises an internal housing that houses the light source, the Fresnel lens, and the microlens, and holds the display unit. The internal housing is provided with positioning pins, The first support portion is provided with a through hole through which the positioning pin is inserted to position the Fresnel lens relative to the internal housing. The vehicle display device according to claim 3, characterized in that the first opposing portion is provided with a through hole through which the positioning pin is inserted to position the microlens relative to the Fresnel lens.

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