Head-up display device

Provided is a head-up display device that can detect background brightness with a simple constitution. A HUD device (1) is provided with: a display device (20) that outputs display light (L) that shows a display image; a combiner (50) that has a concave surface (50a) to which the display light (L) output by the display device (20) is incident, said combiner (50) concentrating the incident display light (L) so as to allow an observer (2) to see the display image from the concave surface (50a) side superimposed on a background from the front; and an optical sensor (31) that is positioned below the combiner (50) and detects the brightness of the light reaching that optical sensor (31). The combiner (50) has a light guide body (60) which is at the lower edge part thereof and is integrated with the combiner (50). The light guide body (60) has a facing surface (62) facing the optical sensor (31) in the vertical direction and guides external light incident from the front downward, outputting the guided light from the facing surface (62). The optical sensor (31) detects the brightness of the light output from the facing surface (62).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Phase of PCT/JP2013/056261 filed Mar. 7, 2013, which claims priority to Japanese Patent Application No. 2012-078120 filed Mar. 29, 2012. The subject matter of each is incorporated herein by reference in entirety.

TECHNICAL FIELD

The present invention relates to a head-up display device.

BACKGROUND ART

As a head-up display (HUD) device, for example, one disclosed in Patent Literature 1 is known. The HUD device is provided with a display unit for displaying an image, and a combiner that can magnify and display the image, and can transmit a scene (background) in front of a vehicle, and is configured to allow a user to see display information such as a vehicle speed and mileage being superimposed on the front scene. The HUD device is further provided with an optical sensor for detecting background brightness for adjusting display brightness of the display unit in accordance with ambient brightness.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. H9-54276

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

The HUD device according to the Patent Literature 1 requires exclusive parts (a prism16, a reflector17) for guiding light to be detected to an optical sensor as shown inFIG. 6andFIG. 7attached to the Document, and the configuration tends to be complex.

The present invention has been made in view of the above circumstances, and it is an object to provide a head-up display device that can detect background brightness with a simple configuration.

Means for Solving the Problem

In order to achieve the above object, a head-up display device according to an aspect of the invention comprises:

a display unit that emits display light representing a display image;

a combiner that has a concave surface to which the display light emitted by the display unit is incident, and concentrates the incident display light to allow an observer to see the display image from the concave surface side superimposed on a background of the front; and

an optical detector that is positioned below the combiner, and detects brightness of light reached,

wherein the combiner has a light guide body that is integrated with the combiner at a lower end part thereof,

the light guide body has a facing surface that faces the optical detector in a vertical direction, guides external light from at least one of the front and above downward, of the external light incident, and emits the external light guided downward from the facing surface, and

the optical detector detects brightness of the light emitted from the facing surface.

In the head-up display device, the light guide body may has a reflection surface that reflects downward the external light incident from the front, and may be configured to emit the external light reflected by the reflection surface from the facing surface.

The head-up display device may be provided with a cover part that covers a part of the facing surface from the lower side, and disturbs the optical path of the light that is passed through the light guide body from above the combiner, and directed downward.

In the head-up display device, a light-shielding cover member that covers the upper side of the combiner may be provided, and may be configured to prevent incidence of external light from the upper side.

The head-up display device may be provided with an adjustment means that adjusts the display brightness of the display unit based on the brightness of the light detected by the optical detector.

Effect of the Invention

According to the present invention, it is possible to provide a head-up display device capable of detecting background brightness with a simple configuration.

MODES FOR CARRYING OUT THE INVENTION

Hereinafter, a HUD device according to an embodiment of the present invention will be described with reference to the drawings.

The HUD device1comprises, as shown inFIGS. 1 to 3, a case body10, a display unit20, a circuit board30, a reflection part40, a combiner50, a light guide body60formed integrally with the combiner50, and a cover member70.

The HUD device1is configured as a stationary HUD device that is installed on a vehicle dashboard (e.g., above an instrument panel). In the following description, the components of the HUD device will be appropriately explained, assuming that as seen from an observer to see a display image displayed by the HUD device1, an upward direction is “up”, a downward direction is “down”, a forward direction is “front”, and a backward direction is “back”, respectively (see the arrows at both ends ofFIG. 1andFIG. 3).

The case body10comprises an upper case11, a lower case12, and a middle case13. In the upper case11, a first opening part110is formed. A shape like a box with the upper side opened is formed by connecting the upper case11and lower case12. In the box shape, the display unit20, the circuit board30, and the middle case13are housed.

The upper case11has a mounting part (not shown) to mount the combiner50, on the side ahead of the first opening part110thereof. A lower end part of the combiner50is fixed to the mounting part with a screw, for example. In this manner, the upper case11holds the combiner50. The combiner50held by the upper case is shaped such as extended upward from the upper case11.

Further, in the upper case11, a second opening part111is formed for exposing the light guide body60forward and passing incident light (external light N1described later) through the inside of the case body10.

The middle case13is placed on the lower case12. In the lower case12, as shown inFIG. 3, a concave part121having a shape corresponding to the lower end portion of the reflection part40is formed. The reflection part40is held by the concave part121and a part (a rear inner surface) of the middle case13. (For example, the reflection part40is held with one end inserted into the concave part121and a rear side surface fixed to the middle case13with adhesive tape or the like.)

The middle case13is a substantially cylindrical member, and the display unit20is disposed on a part of the outside surface thereof (on the right side inFIG. 3). In the middle case13, an emission port130that is a port to expose a display surface of the display unit20is formed. The middle case13may be provided with a transparent window member covering the emission port130.

The display unit20is configured to emit display light L representing a display image for notifying display information such as a vehicle speed and mileage, and comprises of a transmissive liquid crystal display comprising a liquid crystal panel and a backlight light source, or a self-luminous display, for example.

The circuit board30is a printed circuit board formed by implementing a control unit (not shown) comprised of a microcomputer including a memory, such as a CPU and ROM, a graphic display controller (GDC) or the like on a place-shaped base material made of resin including a glass fiber or the like. The circuit board30is fixed to the lower case12by a not-shown fixing member, for example, and is located in front of the display unit20and between the upper case11and lower case12. The circuit board30and display unit20are conductively connected via a flexible printed circuit (FPC)3. One end of the FPC3is connected to the circuit board30via a connector C. The control unit acquires vehicle state information transmitted from an external device (not shown) such as a vehicle electronic control unit (ECU) via a communication line, and drives the display unit20according to the information (namely, displays a predetermined display image on the display unit20).

On the circuit board30, an optical sensor31, an amplifier circuit (not shown), a drive circuit (not shown) to drive the display unit20or the like are mounted.

The optical sensor31is for detecting brightness of light reached, and disposed opposite to a facing surface62of the light guide body60described later, so that an optical axis of light incident to the optical sensor31is along the vertical direction (seeFIG. 4). The optical sensor31supplies the amplifier circuit with a detection signal representing the brightness of light reached. The amplifier circuit amplifies the detection signal detected by the optical sensor31, and supplies it to the control unit. The control unit adjusts the brightness of the display image displayed by the display unit20via the drive circuit based on the obtained detection signal. For example, when a value indicating the brightness of the light received by the optical sensor31is lower than a threshold value (previously stored), a background is assumed to be dark. Thus, The display brightness of the display unit20is increased by a predetermined degree. Specifically, for example, when the display unit20comprises a transmissive liquid crystal display, the brightness of the backlight light source is increased.

The reflection part40is located on the display side of the display unit20, that is, the exit side of the display light L, and reflects the reached display light L toward the combiner50. The reflection part40is made of an aluminum deposited resin molded product, for example, and has a reflection surface configured as a curved surface for effectively reflecting the display light L from the display unit20to the combiner50(inFIG. 3, the reflection surface is schematically shown as a plane). Further, as the reflection part40is held by the concave part121and a part of the middle case13as described before, the reflection surface is arranged so as to substantially facing the display side of the display unit20. The display light L emitted by the display unit20reaches the reflection part through the emission port130. The display light L reflected by the reflection part40is directed to the combiner50through the first opening part110of the upper case11.

The combiner50comprises a plate-shaped half-mirror having a curved surface, a hologram element, or the like. As described before, the combiner50is attached to the upper case11, and a concave surface50athereof is substantially opposite to the reflection surface of the reflection part40. As shown inFIG. 3, the combiner50changes the optical path of the incident display light L after reflected by the reflection part40(changes the optical path of the display light L by reflection when a half-mirror is used as the combiner50, and changes the optical path of the display light L by diffraction when a hologram element is used). The concave surface50aof the combiner50has a function of condensing the display light L, and is configured as a curved surface capable of forming a virtual image far front (for example, about 1 m ahead of the combiner50) compared with the case of simply reflecting the light. The combiner50forms a virtual image of a display image at a front position F thereof, and passes the light from the front, whereby the HUD device1can allow an observer2to see both a virtual image and a real scene present in the front.

The light guide body60is formed integrally with the combiner50, and projected downward from a part of the lower end portion of the combiner50, for example, as shown inFIG. 2. (For reference, inFIG. 2, the lower end UL of the combiner50is represented by a dotted line.) As shown inFIG. 3, the cross-section of the light guide body60is formed in a substantially triangular shape.

The light guide body60is for guiding external light from a predetermined direction toward the optical sensor31, and formed having a reflection surface61and a facing surface62.

The reflection surface61is an inclined surface on the rear side of the light guide body60(inclined by 45° with respect to the longitudinal direction, for example), and effectively reflects downward the external light N1incident from the front to the light guide body60as shown inFIG. 4(hereinafter, external light from the front is given a reference symbol “N1”).FIG. 4shows a magnified essential part of the HUD device1in the schematic cross-sectional view shown inFIG. 3. InFIG. 4, a hatching representing a cross section is omitted (same inFIGS. 5(a) and (b) according to a modification described later).

The facing surface62is a lower surface of the light guide body60, and is a surface opposite to the optical sensor31in the vertical direction. The facing surface62functions as an emission surface that emits the light guided downward by the light guide body60to the outside.

A part of a front part11F that is a part of the upper case11ahead of the combiner50serves as a cover part112covering a part of the facing surface62from the lower side. The upper case11is configured such that the cover part112covers only a part of the optical path of the external light N1that is reflected by the reflection surface61, emitted from the facing surface62, and directed to the optical sensor31.

The cover member70is a member covering a side of the combiner50, and made of a light-shielding resin material. The cover member70is provided for protecting a side of the combiner50(for example, protection from shock) and for preventing the incidence of external light to the combiner50(particularly, from the upper side surface located above the optical sensor31). Of course, as shown inFIG. 2, the cover member70is configured not to cover a part of the light guide body60.

It is also possible to prevent the light incident from the upper side of the combiner50from reaching the optical sensor31as much as possible by the cover part112without providing the cover member70. For this purpose, the cover part112may be provided so as to block the optical path of the external light incident from the upper side of the combiner50(namely, the external light directed downward without being reflected by the reflection surface61) without disturbing the optical path of the external light that is reflected by the reflection surface61and directed downward.

Now, how the external light N1reaches the optical sensor31will be explained by referring toFIG. 4.

The external light N1from the front of the combiner50enters from the front side of the light guide body60, and reflects on the reflection surface61. The reflected external light N1is guided to the inside of the light guide body60, directed downward, and emitted from the facing surface62.

The external light N1emitted from the facing surface62reaches the optical sensor31opposing the facing surface62. The optical sensor31detects the brightness of the external light N1, and in response thereto, the control unit appropriately adjusts the brightness of the display unit20based on the detection result as described before.

Particularly, in the embodiment, as the cover member70is provided on the side of the combiner50, external light does not enter from the side (particularly, the upper side of the upper part of the optical sensor31). Thus, the external light N1mainly from the front can be sensed. In this manner, as the front of the combiner50is a background direction for the observer2when watching a display image, the brightness of the external light N1can be regarded as the brightness of substantially background. Thus, for example, even when the vehicle interior is dark in the daytime in a tunnel near an exit and a display image projecting direction (namely, forward and background direction) is bright, it is possible to adjust the brightness of the projected image to appropriate brightness in accordance with the brightness in the projecting direction before the vehicle leaves the tunnel.

From here, a HUD device according to a modification will be explained by referring toFIGS. 5(a) and (b). Parts having similar functions as those of the embodiment will be denoted by the same reference numerals, and description overlapping with the embodiment will be omitted.

A HUD device101according to a modification 1 is, as shown inFIG. 5(a), configured to detect not only external light N1from the front, but also external light N2from above (hereinafter, external light from above is denoted by a reference symbol “N2”).

For detecting the external light N2from above, a cover member70may not be provided, or at least a part of the cover member70located above an optical sensor31(the part near a B-B line inFIG. 2) May be cut out. Of course, in this case, a cover part112is provided so as not to disturb the optical path of the external light N2incident from the upper side of a combiner50.

Such a configuration is useful when background brightness can be more reflected by detecting the external light N2from above, in accordance with the vehicle interior environment.

A HUD device201according to a modification 2 is, as shown inFIG. 5(b), configured to be able to detect external light N2from above without detecting external light N1from the front as much as possible.

In this case, similar to the modification 1, a cover member70may not be provided, or at least a part of the cover member70located above an optical sensor31may be cut out. A cover part112is provided so as not to disturb the optical path of the external light N2incident from the upper side of a combiner50. To detect only the external light N2from above, the reflection surface61as described above is not formed in a light guide body260according to the modification 2.

Such a configuration is useful when the external light N2from above is dominant to the background brightness due to any factor.

The HUD device1(or101,201) explained above comprises a display unit20that emits display light L representing a display image;

a combiner50that has a concave surface50ato which the display light L emitted by the display unit20is incident, and concentrates the incident display light L so as to allow an observer2to see the display image from the concave surface50aside superimposed on a background of the front; and

an optical sensor31(an example of an optical detector) that is positioned below the combiner50, and detects brightness of light reached, wherein the combiner50has a light guide body60that is integrated with the combiner50at a lower end part thereof,

the light guide body60has a facing surface62that faces the optical sensor31in a vertical direction, guides external light from at least one of the front and above downward, of the external light incident, and emits the external light guided downward from the facing surface62, and the optical sensor31detects brightness of the light emitted from the facing surface62.

As described above, since the light guide body for guiding light to the optical sensor is configured integrally with the combiner, the HUD device1(or101,201) has a simple structure. Further, as the number of parts can be decreased, the cost can be reduced.

Particularly, in the HUD device1and the HUD device101according to the modification 1, the light guide body60has a reflection surface61that reflects downward the external light N1incident from the front, and emits the external light reflected by the reflection surface61from the facing surface62. Thus, as described above, it is possible to effectively detect the brightness in the background direction.

The present invention is not to be limited to the aforementioned embodiment, modifications (modifications 1 and 2), and drawings. It is of course possible to add various changes and modifications (including elimination of the constituent elements) to them.

The above description shows an example that the angle of the reflection surface61of the light guide body60is 45 degrees, but not limited thereto. It is possible to adjust (suppress) the amount of the external light N1reaching the optical sensor31by displacing the reflection surface61from the tilt angle of 45 degrees.

The above description shows an example that the display light L from the display unit20is reflected by the reflection part40and reached to the combiner50, but not limited thereto. The HUD device may be configured such that the display unit emits the display light L directly to the combiner. In this case, the display unit and combiner are arranged so as to substantially opposite to each other, and the reflection part40is unnecessary.

In the above description, an automobile is taken as an example of vehicles to install the HUD device1(hereinafter, including the HUD devices101and201), but not to be limited thereto. The HUD device1may be installed in the vicinity of a driver's seat in a ship, an airplane, or other vehicles. Further, the installation place is not limited to the vicinity of a driver's seat of a vehicle. It may also be applied to tabletop interiors or the like to be placed indoors.

In the above description, the HUD device1has been explained as a stationary type. However, for example, the HUD device1may be configured integrally with a dashboard of a vehicle.

In the above description, unimportant known techniques are appropriately omitted to facilitate understanding of the present invention.

INDUSTRIAL APPLICABILITY

In the aforementioned embodiment, a head-up display device for a vehicle has been explained as an example of application. However, it is possible to apply the invention to a ship or special vehicles such as agricultural machinery and construction equipment.

DESCRIPTION OF REFERENCE NUMERALS