Head-up display device and image projection unit

A head-up display device projects display light of an image on a projection member to virtually display a virtual image of the image. An illumination light source unit emits an illumination light. An image display panel causes the illumination light from the illumination light source unit to pass therethrough to be emitted as a display light from a display surface to display the image. A projection lens is located between the illumination light source unit and the image display panel and projects the illumination light from the illumination light source unit onto the image display panel. The image display panel is tilted so that a normal direction to the display surface intersects with an optical axis of the illumination light source unit. The projection lens is tilted so that a radial direction of the projection lens coincides with a tangential direction to the display surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/JP2017/014477 filed on Apr. 7, 2017. This application is based on and claims the benefit of priority from Japanese Patent Application No. 22016-099852 filed on May 18, 2016. The entire disclosures of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a head-up display device mounted on a movable object and configured to virtually display an image to be visible to an occupant.

BACKGROUND ART

Conventionally, a head-up display device (hereinafter abbreviated as HUD device) configured to virtually display an image to be visible to an occupant has been known. The HUD device disclosed in Patent Literature 1 includes an illumination light source unit, an image display panel, and a projection lens. The illumination light source unit emits an illumination light. The image display panel causes the illumination light from the illumination light source unit side to pass through the image display panel and to be emitted from a display surface as a display light to display an image. The projection lens is located between the illumination light source unit and the image display panel, and projects the illumination light from the illumination light source unit side onto the image display panel.

In Patent Literature 1, the image display panel is located so that an optical axis of the illumination light source unit coincides with a normal direction of the display surface. Further, the projection lens is located so that the optical axis is orthogonal to a radial direction of the projection lens.

The present inventor has considered that the image display panel is tilted so that the normal direction of the display surface intersects with the optical axis. According to the tilted image display panel, even when an external light such as sunlight enters the image display panel in a direction opposite to the display light, since the normal direction of the display surface intersects with the external light, the external light is restricted from being reflected by the display surface and visually recognized together with the display light.

On the other hand, the present inventor has found out that the following unique issue arises in the HUD device in which the projection lens for projecting the illumination light onto the tilted image display panel is located such that a radial direction of the projection lens is orthogonal to the optical axis. More specifically, when the projection lens and the image display panel are placed on an optical path with the avoidance of mutual interference between the projection lens and the image display panel, an interval between the projection lens and the image display panel is partially widened due to an angular difference of the placement, and a dead space may occur between the projection lens and the image display panel. As a result, for example, a size of the HUD device increases due to an increase in a distance from the illumination light source unit to a tip of the image display panel. In other words, the mountability of the HUD device to a movable object is deteriorated.

PRIOR TECHNICAL LITERATURE

Patent Literature

PATENT LITERATURE 1: JP 2015-133304 A

SUMMARY OF INVENTION

It is an object of the present disclosure to provide an HUD device with high mountability to a movable object.

According to one aspect of the present disclosure, a head-up display device is configured to be mounted on a movable object and to project a display light of an image on a projection member to display a virtual image of the image to be visually recognizable by an occupant. The head-up display device comprises an illumination light source unit configured to emit an illumination light. The head-up display device further comprises an image display panel configured to cause the illumination light from the illumination light source unit to pass therethrough to be emitted as the display light from a display surface to display the image. The head-up display device further comprises a projection lens located between the illumination light source unit and the image display panel and configured to project the illumination light from the illumination light source unit onto the image display panel. The image display panel is tilted to cause a normal direction to the display surface to intersect with an optical axis of the illumination light source unit. The projection lens is tilted to cause a radial direction of the projection lens to coincide with a tangential direction to the display surface.

According to one aspect of the present disclosure, an image projection unit is for a head-up display device. The head-up display device is configured to be mounted on a movable object and to project a display light of an image on a projection member to display a virtual image of the image to be visually recognizable by an occupant. The image projection unit is configured to project the display light onto a light guide unit, which is configured to guide the display light to the projection member. The image projection unit comprises an illumination light source unit configured to emit an illumination light. The image projection unit comprises an image display panel configured to cause the illumination light from the illumination light source unit to pass therethrough and to be emitted as the display light from a display surface to display the image. The image projection unit comprises a projection lens located between the illumination light source unit and the image display panel and configured to project the illumination light from the illumination light source unit onto the image display panel. The image display panel is tilted to cause a normal direction to the display surface to intersect with an optical axis of the illumination light source unit. The projection lens is tilted to cause a radial direction of the projection lens to coincide with a tangential direction to the display surface.

DESCRIPTION OF EMBODIMENTS

Hereinafter, description will be given of the multiple embodiments of the present disclosure based on the drawings. Corresponding constituent elements in each embodiment are given the same signs, and there are cases in which duplicated explanation is omitted. In a case in which only a portion of the configuration in each embodiment is described, the configuration of another embodiment which is described earlier may be applied for the other portions of the configuration. In addition to the combinations of configurations clearly depicted in the explanation of the embodiments, as long as issues do not particularly arise in a combination, the configurations of multiple embodiments may be partially combined with each other, even when not clearly described.

First Embodiment

As illustrated inFIG. 1, an HUD device100according to a first embodiment of the present disclosure is installed in a vehicle1that is one type of a mobile object, and is housed in an instrument panel2. The HUD device100projects display light of an image onto a windshield3which serves as a projection member of the vehicle1. With the above configuration, the HUD device100virtually displays an image in such a manner as to be visible to an occupant in the vehicle1. In other words, a display light which is reflected on the windshield3reaches an eye point EP of the occupant in a vehicle interior of the vehicle1, and the occupant senses the display light as a virtual image VI. The occupant is capable of recognizing various pieces of information which are displayed as the virtual image VI. Examples of various pieces of information which is displayed as the virtual image VI include vehicle state values such as vehicle speed and remaining fuel level, or vehicle information such as road information and visibility auxiliary information.

The windshield3of the vehicle1is formed in a plate-shape and made of a light transmissive glass or a synthetic resin. In the windshield3, a projection surface3aonto which the display light is projected is formed into a smooth concave surface shape or a flat surface shape. As the projection member, instead of the windshield3, a combiner that is separate from the vehicle1may be installed inside the vehicle1, and the image may be projected onto the combiner. Further, the HUD device100per se may include a combiner as a projection member.

A specific configuration of the HUD device100described above will be described below with reference toFIGS. 1 to 9. The HUD device100includes an illumination light source unit10, a condenser lens20, a projection lens30, an image display panel40, and a light guide unit50. Those components are housed and held in a housing60.

In this example, as shown inFIGS. 1 and 2, an image projection unit19is includes the illumination light source unit10, the condenser lens20, the projection lens30, and the image display panel40. The respective elements10,20,30, and40of the image projection unit19are housed in a casing19ahaving a light shielding property.

As shown inFIGS. 2 to 4, the illumination light source unit10includes a light source circuit board11and multiple light emitting devices12. The light source circuit board11has a planar mounting surface11a. The respective light emitting devices12are, for example, light emitting diode devices with little heat generation and are arrayed on the mounting surface11a. The respective light emitting devices12are electrically connected to a power supply through a wiring pattern on the mounting surface11a. More specifically, each of the light emitting devices12is formed by sealing a chip-shaped blue light emitting diode device with a yellow phosphor in which a light transmissive synthetic resin is mixed with a yellow fluorescent agent. The yellow phosphor is excited by the blue light emitted according to a current amount from the blue light emitting diode device to emit a yellow light, and illumination light of pseudo white is emitted by mixture of the blue light with the yellow light.

In the present embodiment, the respective light emitting devices12are arrayed in a lattice pattern with two directions orthogonal to each other on the mounting surface11aas array-directions. In the respective array directions, the number of light emitting devices12is, for example, 3×5, that is, 15 in total.

In the present embodiment, a normal direction to the planar mounting surface11aof the light source circuit board11is defined as a z-direction. A direction in which the number of aligned elements is larger, that is, a direction in which five elements are aligned among directions along the mounting surface11ais defined as an x-direction. A direction in which the number of aligned elements is smaller, that is, a direction in which three elements are aligned is defined as a y-direction.

Each of the light emitting devices12emits a light with a predetermined light emission intensity distribution, and is located such that a light emission peak direction PD1at which a light emission intensity becomes maximum is aligned with the z-direction (refer toFIGS. 3 and 4). Therefore, in the present embodiment, it is assumed that an optical axis OA of the illumination light source unit10defined based on the configuration of the illumination light source unit10is defined as an axis along the z-direction which is the light emission peak direction PD1. In more detail, the optical axis OA is defined as an axis that passes through a middle light emitting device12located at the center of the illumination light source unit10and extends along the z-direction, which is the light emission peak direction PD1. In other words, the illumination light source unit10emits the illumination light in a direction along the optical axis OA by the respective light emitting devices12. The illumination light emitted from the illumination light source unit10is made incident on the condenser lens20.

The condenser lens20is located between the illumination light source unit10and the projection lens30. The condenser lens20condenses the illumination light from the illumination light source unit10side and emits the condensed illumination light toward the projection lens30.

More specifically, the condenser lens20is configured by a lens array in which multiple convex lens elements22made of light transmissive synthetic resin or glass or the like are arrayed and formed integrally. The respective convex lens elements22are configured by lens elements of the same number as that of the light emitting devices12so as to be paired with the light emitting devices12individually. In other words, the convex lens elements22are arrayed in a matrix of 3×5, that is, 15 in total. In the condenser lens20, an incident side surface20afacing the illumination light source unit10is a single plane having a smooth planar shape common to the respective convex lens elements22. On the other hand, on an emission side surface20bfacing the projection lens30in the condenser lens20, light condensing surfaces23individually provided for the respective convex lens elements22are arrayed.

The condensing surfaces23have substantially the same shape among the convex lens elements22, and each light condensing surface23is formed into a smooth convex shape by being curved into a convex shape protruding toward the projection lens30side. In the present embodiment, intervals of the light emitting devices12aligned with each other and intervals of surface vertices of the light condensing surfaces23aligned with each other are substantially equal to each other. Furthermore, a distance between each light emitting device12and the surface vertex23aof the light condensing surface23of the paired convex lens element22is substantially equal to each other in the respective pairs. In other words, since an array direction of the light emitting devices12substantially coincides with a direction of the aligned convex lens elements22so that a radial direction of the condenser lens20is located substantially perpendicular to the optical axis OA (that is, the z-direction).

Now, a detailed shape of each light condensing surface23will be described. In particular, in the present embodiment, each light condensing surface23is an aspherical surface that is rotationally symmetric with reference to the surface vertex23a. Specifically, each light condensing surface23is formed in a parabolic shape in an xz cross section (refer toFIG. 4) and is also formed in the parabolic shape in a yz cross section (refer toFIG. 3), to thereby provide a paraboloidal shape.

The projection lens30is located between the illumination light source unit10and the image display panel40, and more precisely, between the condenser lens20and the image display panel40. The projection lens30is adapted to project the illumination light incident from the illumination light source unit10side onto the image display panel40.

More specifically, the projection lens30is configured by a lens array in which multiple deflection elements30bmade of light transmissive synthetic resin or glass or the like are arrayed and formed integrally, and has a substantially plate-like shape as a whole. The deflection elements30bare arrayed along a radial direction DD of the projection lens30. Each deflection element30bcan deflect a traveling direction of the illumination light by refraction at divided lens surfaces33and35which will be described later. In the projection lens30according to the present embodiment, divided blocks30ain which the projection lens30is virtually divided can be defined corresponding to a direction and the number of the multiple array light emitting devices12. In particular, according to the present embodiment, a total of 3×5, that is, 15 divided blocks30acan be defined in which the projection lens30is divided into three pieces in the y-direction corresponding to the number of aligned light emitting devices12, and the projection lens30is divided into five pieces in the x-direction corresponding to the number of aligned light emitting devices12. As shown inFIG. 5, the projection lens30configures the multiple deflection elements30barrayed in those respective divided blocks30a. In the present embodiment, a total of 36 (6×6) deflection elements30bcorresponding to the number of divided lens surfaces33and35, which will be described later, are arrayed in one divided block30a.

As shown inFIGS. 2 to 4, in the projection lens30having a substantially plate-like shape according to the present embodiment, the radial direction DD of the projection lens30coincides with an extension direction perpendicular to a plate thickness direction. The projection lens30is tilted so that the plate thickness direction intersects with the optical axis OA (that is, the z-direction).

The image display panel40is configured by a liquid crystal panel formed of a thin film transistor (TFT) and includes, for example, an active matrix liquid crystal panel formed of multiple liquid crystal pixels40athat are arrayed in two directions.

Specifically, as shown inFIG. 6, the image display panel40has a rectangular shape having a longitudinal direction LD and a short direction SD. As shown inFIG. 7, since the liquid crystal pixels40aare arrayed in the longitudinal direction LD and the short direction SD, a display surface44that displays an image on the light guide unit50side also has a rectangular shape. In each liquid crystal pixel40a, a transmissive portion40bpenetrating through the display surface44in a normal direction ND and a wiring portion40cformed so as to surround the transmissive portion40bare provided.

Since the image display panel40is formed by laminating a pair of polarizing plates and a liquid crystal layer sandwiched between the pair of polarizing plates, the image display panel40has a plate-like shape. Each polarizing plate has a property of transmitting a light polarized in a predetermined direction and absorbing a light polarized in a direction perpendicular to the predetermined direction, and the pair of polarizing plates are located such that the predetermined directions are orthogonal to each other. The liquid crystal layer can rotate a polarization direction of the light incident on the liquid crystal layer according to an applied voltage by applying the voltage for each liquid crystal pixel40a. A ratio of the light transmitted through the later polarizing plate due to the rotation of the polarization direction, that is, a transmittance can be changed.

Therefore, the image display panel40controls the transmittance of the illumination light for each liquid crystal pixel40aagainst the incidence of the illumination light on an illumination target surface42which is a surface on the illumination light source unit10side. In other words, the image display panel40transmits a part of the illumination light from the illumination light source unit10side and emits the transmitted illumination light from the display surface44which is a surface of the light guide unit50side as display light, thereby being capable of displaying the image. Color filters of mutually different colors (for example, red, green, and blue) are provided in adjacent liquid crystal pixels40a, and various colors are realized by the combinations of those color filters.

The display surface44is formed so as to be able to reflect the light incident on the image display panel40from the light guide unit50side with the use of a mirror-like surface of a glass substrate in the image display panel40, for example.

As shown inFIGS. 2 to 4, the illumination light enters the illumination target surface42of the image display panel40along the optical axis OA. On the other hand, the image display panel40is tilted so that the normal direction ND to the illumination target surface42and the display surface44intersects with the optical axis OA. Specifically, the image display panel40is tilted so that the longitudinal direction LD is orthogonal to the optical axis OA and the short direction SD is tilted relative to the optical axis OA in the tangential directions TD to the display surface44. The longitudinal direction LD extends along the x-direction. In other words, the image display panel40is rotated with the longitudinal direction LD (that is, the x-direction) as a rotation axis from a posture in which the normal direction to the display surface44is orthogonal to the optical axis OA. An intersection angle θ of the normal direction ND of the display surface44to the optical axis OA is, for example, about 10 to 25 degrees.

Since there is basically no element for deflecting the light in the image display panel40of the present embodiment, an emission peak direction PD2, in which an emission intensity is the largest among the display light, is not changed in the image display panel40, and extends roughly along the optical axis OA. In other words, the emission peak direction PD2of the display light is different from the normal direction ND to the display surface44. In this way, the image projection unit19projects the display light toward the light guide unit50.

As shown inFIG. 1, the light guide unit50guides the display light from the image display panel40of the image projection unit19to the windshield3. The light guide unit50according to the present embodiment has a plane mirror51and a concave mirror53. In the present embodiment, the display light from the image display panel40first enters the plane mirror51.

The plane mirror51is formed by depositing aluminum as a reflection surface52on a surface of a base material made of synthetic resin or glass, or the like. The reflection surface52is formed in a smooth planar shape. The display light incident on the plane mirror51is reflected by the reflection surface52toward the concave mirror53.

The concave mirror53is formed by depositing aluminum as a reflection surface54on a surface of a base material made of synthetic resin, glass, or the like. The reflection surface54is curved in a concave shape concaved in the center of the concave mirror53so as to be formed in a smooth concave surface shape. The display light incident on the concave mirror53is reflected by the reflection surface54toward the windshield3.

A window61is provided in the housing60between the concave mirror53and the windshield3. The window61is closed with a light transmissive dustproof cover62. Therefore, the display light from the concave mirror53passes through the dustproof cover62and is incident on the windshield3. In this way, the occupant can visually recognize the display light reflected by the windshield3as the virtual image VI.

In such an HUD device100, an external light of, for example, sunlight or the like may pass through the windshield3and enter the window61. A part of the external light incident on the window61may be reflected in reverse to the display light, in other words, reflected by the concave mirror53and the plane mirror51of the light guide unit50in order, and be reflected on the display surface44of the image display panel40. In this example, in the image display panel40, since the normal direction ND to the display surface44intersects the optical axis OA, the external light incident on the display surface44can be reflected in a direction different from that of the display light.

It is preferable that an inclination direction or an angle of the image display panel40is set so as to satisfy a Scheimpflug condition or to come close to the condition in consideration of placement angles of the plane mirror51, the concave mirror53, and the windshield3. According to the inclination direction and the angle described above, the virtual image VI viewed from the eye point EP can be restricted from being inclined and visually recognized.

As shown inFIGS. 2 to 4, the projection lens30is also tilted corresponding to the image display panel40. Specifically, the projection lens30is tilted so that the radial direction DD of the projection lens30is aligned with the tangential direction TD to the display surface44. As a result, as described above, the plate thickness direction of the projection lens30intersects with the optical axis OA (that is, the z-direction).

The image display panel40and the projection lens30according to the present embodiment are located so as to avoid an interference with each other. In the present specification, the interference includes not only a spatial interference that the image display panel40collides with the projection lens30but also an optical interference. If an interval between the image display panel40and the projection lens30is partially narrowed by an angular difference of placement, Moire fringes can be observed only in a part of the image. In such Moiré fringes, there is a concern that boundaries between the adjacent deflection elements30bin the projection lens30described above may be emphasized.

Taking the above issues into consideration, it is preferable that the interval between the image display panel40and the projection lens30is kept constant. In particular, in the present embodiment, when the interval between the image display panel40and the projection lens30is kept constant, the image display panel40and the projection lens30are located in parallel to each other.

A shape of the projection lens30is adapted to such a tilted placement. Hereinafter, the shape of the projection lens30will be described in detail with reference toFIGS. 8 and 9.

As shown inFIG. 8, on the incident side surface32of the projection lens30which faces the condenser lens20, the multiple divided lens surfaces33are formed as components of the deflection elements30bin a state of being divided into stripes so as to be coincident with the boundaries between the adjacent deflection elements30b. A dividing direction of the divided lens surfaces33on the incident side surface32is along the short direction SD inclined, for example, by about 10 to 25 degrees from the y-direction. Therefore, in the xz cross section, one divided lens surface33is formed across the deflection element30band the divided block30a. Each divided lens surface33is located such that a component of the divided lens surface33in the xz cross section in the normal direction to the divided lens surface33is aligned with the optical axis OA and a component of the divided lens surface33in the yz cross section in the normal direction to the divided lens surface33intersects with the optical axis OA. Therefore, the incident side surface32is mainly configured to deflect the traveling direction of the illumination light in the yz cross section.

On the other hand, as shown inFIG. 9, on the emission side surface34of the projection lens30which faces the image display panel40, the multiple divided lens surfaces35are formed as components of the deflection elements30bin a state of being divided into stripes so as to be coincident with the boundaries between the adjacent deflection elements30b. The dividing direction of the divided lens surfaces35in the emission side surface34is aligned with the longitudinal direction LD (that is, the x-direction). Therefore, in the yz cross section, one divided lens surface35is formed across the deflection element30band the divided block30a. Each divided lens surface35is located such that a component of the divided lens surface35in the yz cross section in the normal direction to the divided lens surface35is aligned with the optical axis OA and a component of the divided lens surface35in the xz cross section in the normal direction to the divided lens surface35intersects with the optical axis OA. Therefore, the emission side surface34is mainly configured to deflect the traveling direction of the illumination light in the xz cross section.

First, each divided lens surface35on the emission side surface34will be described. The emission side surface34has substantially the same shape for each of the divided blocks30awhich are divided into five pieces according to the number of aligned light emitting devices12corresponding to the x-direction.

In this example, when attention is focused on one divided block30a, multiple approximate planes35aand multiple anisotropic deflection planes35bare provided as the divided lens surfaces35. The respective approximate planes35aand the respective anisotropic deflection planes35bare formed as one divided region which is divided with a predetermined division width Wa. In the present embodiment, the predetermined division width Wa is set to be substantially constant.

The approximate planes35aare formed based on a virtual convex curved surface Svb defined as a virtual lens surface in the projection lens30. In this example, the virtual convex curved surface Svb has a smooth cylindrical surface shape which is curved into a convex shape convexed toward the image display panel40side in the xz cross section. The approximate planes35aare formed in a planar shape as an approximate plane obtained by linear interpolation of multiple coordinates extracted from the virtual convex curved surface Svb. In particular, in the present embodiment, as the multiple coordinates, end coordinates Ce of the virtual convex curved surfaces Svb at ends of the divided regions are adopted, and a gradient of the approximate planes35ais defined by linear interpolation between the end coordinates Ce. The virtual convex curved surface Svb appears on the emission side surface34in a state of being planar by partial approximation.

The anisotropic deflection planes35bare interposed between the approximate planes35a. The anisotropic deflection planes35bare formed based on a virtual inclined surface Ssb defined as a virtual lens plane in the projection lens30. The virtual inclined surface Ssb is configured by multiple planar inclined surfaces Ssp that change in a reverse gradient at a position corresponding to a surface vertex of the virtual convex curved surface Svb in the xz cross section and the gradient of each planar inclined surface Ssp is set to be a gradient in a direction opposite to that of the gradient of a corresponding portion of the virtual convex curved surface Svb. When a part of the virtual inclined surface Ssb is extracted, the anisotropic deflection plane35bappears on the emission side surface34.

In particular, in the present embodiment, six divided lens surfaces35are set for one divided block30a. The six divided lens surfaces35are arrayed in the order of the approximate plane35a, the anisotropic deflection plane35b, the approximate plane35a, the approximate plane35a, the anisotropic deflection plane35b, and the approximate plane35a, and a boundary between the adjacent approximate planes35acorresponds to a surface vertex of the virtual convex curved surface Svb. Therefore, since the gradient is switched to the reverse gradient for each of the divided lens surfaces35, even if the boundary between the divided lens surfaces35is connected to each other without a step, the projection lens30is kept substantially in a plate-like shape.

Next, each divided lens surface33on the incident side surface32will be described. As shown inFIG. 8, the incident side surface32is configured with a different shape for each of the divided blocks30awhich are divided into three pieces according to the number of aligned light emitting devices12corresponding to the x-direction.

In this example, when attention is focused on one divided block30a, as with the emission side surface34, multiple approximate planes33aand multiple anisotropic deflection planes33bare provided as the divided lens surfaces33. The respective approximate planes33aand the respective anisotropic deflection planes33bare formed as one divided region which is divided with a predetermined division width Wa. In the present embodiment, the predetermined division width Wa is set to be substantially constant.

The approximate planes33aare formed based on a virtual convex curved surface Sva defined as a virtual lens surface in the projection lens30. In this example, the virtual convex curved surface Sva has a smooth cylindrical surface shape which is curved into a convex shape convexed toward the condenser lens20side in the yz cross section. The approximate planes33aare formed in a planar shape as an approximate plane obtained by linear interpolation of multiple coordinates extracted from the virtual convex curved surface Sva. In particular, in the present embodiment, as the multiple coordinates, end coordinates Ce of the virtual convex curved surfaces Sva at ends of the divided regions are adopted, and a gradient of the approximate planes33ais defined by linear interpolation between the end coordinates Ce. The virtual convex curved surface Sva appears on the incident side surface32in a state of being planar by partial approximation. It should be noted that the end coordinates Ce are shown in a part ofFIG. 9and are omitted inFIG. 8because of the same.

The anisotropic deflection planes33bare interposed between the approximate planes33a. The anisotropic deflection planes33bare formed based on a virtual inclined surface Ssa defined as a virtual lens plane in the projection lens30. The virtual inclined surface Ssa is configured by multiple planar inclined surfaces Ssp that change in a reverse gradient at a position corresponding to a surface vertex of the virtual convex curved surface Sva in the yz cross section and the gradient of each planar inclined surface Ssp is set to be a gradient in a direction opposite to that of the gradient of a corresponding portion of the virtual convex curved surface Sva. A part of the virtual inclined surface Ssa is extracted and appears on the emission side surface34.

In particular, in the present embodiment, six divided lens surfaces33are set for one divided block30a. The six divided lens surfaces33are arrayed in the order of the approximate plane33a, the anisotropic deflection plane33b, the approximate plane33a, the approximate plane33a, the anisotropic deflection plane33b, and the approximate plane33a, and a boundary between the adjacent approximate planes33acorresponds to a surface vertex of the virtual convex curved surface Sva. Therefore, since the gradient is switched to the reverse gradient for each of the divided lens surfaces33, even if the boundary between the divided lens surfaces33is connected to each other without a step, the projection lens30is kept substantially in a plate-like shape.

In this example, in the incident side surface20a, unlike the emission side surface20b, the gradient of the approximate plane33ais different for each divided block30a. In detail, the radius of curvature Rv of the virtual convex curved surface Sva as the base is different in each of the divided blocks30a. Therefore, the gradient of the approximate plane33ais different for each of the divided blocks30a.

In particular, in the present embodiment, the radius of curvature Rv of the virtual convex curved surface Sva of each divided block30achanges so as to be smaller from a short distance side of the tilted projection lens30where a distance from the illumination light source unit10is short toward a long distance side of the tilted projection lens30where the distance from the illumination light source unit10is a long distance. Specifically, when it is assumed that the radius of curvature is set to Rv1, Rv2, and Rv3in order from the divided block30aon the short distance side, Rv1<Rv2<Rv3is satisfied. Therefore, the gradient of the approximate plane33ain the divided block30aon the long distance side is relatively large as compared with the gradient on the short distance side.

The gradient of the anisotropic deflection plane33bis set to be substantially equal in each divided block30a.

For each divided block30ain the yz cross section, a portion on the approximate plane33acorresponding to the surface vertex of the virtual convex curved surface Sva is aligned substantially with a straight line SL extending along the optical axis OA toward the projection lens30side from the surface vertex23aof the corresponding light condensing surface23in the condenser lens20. With the above correspondence relationship, one illumination unit IU is configured by one light emitting device12, one convex lens element22, and one divided block30acorresponding to each other (also refer toFIGS. 3 and 4). The illumination light source unit10, the condenser lens20, and the projection lens30in the present embodiment can be understood as an array of such illumination units IU.

The illumination light from the light condensing surface23located closer to the illumination light source unit10than the projection lens30is incident on each of the divided lens surfaces33. Among the incident illumination light, the traveling direction of the illumination light incident on the approximate plane33ais deflected so as to come closer to the corresponding straight line SL. In this example, the amount of deflection by which the illumination light is deflected corresponds to the gradient of each approximate plane33awith respect to the radial direction DD.

In the present embodiment, a composite focal point of the condenser lens20and the projection lens30can be defined according to the radius of curvature of the light condensing surface23of the condenser lens20and the radius of curvature Rv of the virtual convex curved surfaces Sva and Svb which are the basis of the approximate planes33aand35aof the projection lens30. Since the position of the composite focal point and the position of the illumination light source unit10are set to come close to each other, the illumination lights refracted by the different approximate planes33aare deflected so that the components in the traveling direction in the yz cross section come close to each other. In addition, the illumination lights refracted by the different approximate planes35aare deflected so that the components in the traveling direction in the xz cross section come close to each other. Therefore, the illumination lights refracted by the different deflection elements30bare collimated more than the illumination light before being incident on the projection lens30.

In more detail, a composite focal point of the convex lens element22and the divided block30acan be defined according to the radius of curvature of the light condensing surface23in each illumination unit IU and the radius of curvature Rv of the virtual convex curved surfaces Sva and Svb which are the basis of the approximate planes33aand35ain the divided block30a. The position of the composite focal point is defined for each illumination unit IU. Since the position of the composite focal point and the position of the corresponding light emitting device12are set to come close to each other, the illumination lights refracted by the different approximate planes33aare deflected in the same divided block30aso that the components in the traveling direction in the yz cross section come close to each other. In addition, in the same divided block30a, the illumination lights refracted by the different approximate planes35aare deflected so that the components in the traveling direction in the xz cross section come close to each other.

With the tilted placement of the projection lens30, a distance between the divided block30aand the light emitting device12on the yz cross section is different in each of the illumination units IU. The radius of curvature Rv of the virtual convex curved surface Sva which is the basis of the approximate plane33ais set to be different for each divided block30ain correspondence with the above distance, as a result of which the position of the composite focal point and the position of the corresponding light emitting device12can be set to come closer to each other.

On the other hand, the anisotropic deflection plane35blocated adjacent to the approximate planes33aand35adeflects the illumination light in a direction different from that of the separated approximate planes33aand35aby refraction. As a result, a part of the illumination light is mixed with the illumination light obtained by allowing a part of the illumination light incident on the projection lens30to be refracted by the approximate planes33aand35adue to the refraction by the anisotropic deflection planes33band35b. Therefore, the display light emitted from the display surface44of the image display panel40is restricted from being concentrated in the emission peak direction PD2and emitted.

The function of each deflection element30bis exerted by the combination of striped divided lens surfaces33and35extending substantially perpendicular to each other on both surfaces32and34of the projection lens30. Specifically, a basal direction and the amount of deflection in the deflection of the illumination light of each deflection element30bcan be determined according to the gradient in the yz cross section of the divided lens surface33on the incident side surface32and the gradient in the xz cross section of the divided lens surface35on the emission side surface34. The amount of deflection can be expressed by, for example, an angular difference between the incident angle of the illumination light to one deflection element30band the emission angle.

In such a projection lens30, an average value of the deflection amounts of the deflection elements30bconfiguring each divided block30agradually changes from the short distance side toward the long distance side. In particular, in the present embodiment, the average value of the deflection amounts of the respective deflection elements30bconfiguring the divided block30ais larger on the long distance side.

In other words, the average value of the deflection amounts of the deflection elements30blocated on the short distance side of the projection lens30and the average value of the deflection amounts of the deflection elements30blocated on the long distance side are different from each other. In particular, in the present embodiment, the average value of the deflection amounts of the deflection elements30blocated on the long distance side is larger than the average value of the deflection amounts of the deflection elements30blocated on the short distance side.

Operations and Effects

The operations and effects of the first embodiment which is described above will be described hereinafter.

According to the first embodiment, in the image display panel40, the normal direction ND to the display surface44is deviated from the optical axis OA. In addition, the projection lens30is tilted so as to align the radial direction DD with the tilted image display panel40. According to the inclination of both of the projection lens30and the image display panel40, since there is no angular difference of the placement, an interference between the projection lens30and the image display panel40is restricted, and a dead space can be restricted from occurring between the projection lens30and the image display panel40. Therefore, the HUD device100having high mountability on the vehicle1as the movable object, which is capable of restricting an increase in the size of the HUD device100can be provided.

Further, according to the first embodiment, the image display panel40and the projection lens30are located in parallel to each other. With that configuration, a distance between the projection lens30and the image display panel40can be minimized while restricting the interference between the projection lens30and the image display panel40.

According to the first embodiment, the condenser lens20located between the illumination light source unit10and the projection lens30has the light condensing surface23that is curved in the convex shape protruding toward the projection lens30side. Therefore, when the projection lens30is tilted according to the image display panel40, an end of the projection lens30which comes closer to the condenser lens20side goes around a lateral space of the light condensing surface23along the curvature of the condensing surface23. For that reason, an increase in the distance from the illumination light source unit10to the tip of the image display panel40can be restricted while obtaining the condensing action by the condenser lens20and avoiding the interference between the projection lens30and the condenser lens20. Therefore, the HUD device100having high mountability on the vehicle1, which is capable of restricting an increase in the size of the HUD device100can be provided.

According to the first embodiment, the projection lens30includes the multiple deflection elements30bthat are aligned with each other along the radial direction DD and deflect the traveling direction of the illumination light. The projection lens30is formed in a plate-shape by the array of the deflection elements30b, thereby being capable of not only restricting an increase in the size of the HUD device100, but also realizing appropriate illumination on each portion of the tilted image display panel40by the deflecting action of each deflection element30b.

According to the first embodiment, the average value of the deflection amounts of the deflection elements30blocated on the short distance side of the projection lens30and the average value of the deflection amounts of the deflection elements30blocated on the long distance side are different from each other. Even if the distances from the illumination light source unit10are different at the respective positions of the projection lens30, the different deflection amounts are set so as to realize the appropriate illumination according to the distances from the illumination light source unit10on the respective portions of the tilted image display panel40.

In addition, according to the first embodiment, the average value of the deflection amounts of deflection elements30bconfiguring each divided block30agradually changes from the short distance side toward the long distance side. With the above configuration, the illumination light corresponding to each light emitting device12is subject to a deflecting action having a different degree depending on the distance from the illumination light source unit10. Therefore, even when the distances from the illumination light source unit10are different at the respective positions of the projection lens30, the preferable illumination for the tilted image display panel40can be realized.

Further, according to the first embodiment, the projection lens30includes the multiple approximate planes33aor35aformed in the planar shape by partial approximation of the virtual convex curved surface Sva or Svb as a component of the deflection element30b. Although each approximate plane33aor35ais planar, since the approximate plane33aor35ais based on the common virtual convex curved surface Sva or Svb, the traveling direction of the illumination light incident on the different approximate plane33aor35ais reflected by the amount of deflection corresponding to the virtual convex curved surface Sva or Svb. Therefore, substantially the same action as the light condensing action can occur between the respective illumination lights. Therefore, a restriction of an increase in size of the HUD device100and suitable illumination for the tilted image display panel40can be realized with ease of forming the projection lens30.

Further, according to the first embodiment, the image projection unit19having the image display panel40in which the normal direction ND to the display surface44intersects with the optical axis OA projects the display light onto the light guide unit50. According to the image projection unit19configured as described above, even when an external light such as sunlight enters the image display panel40in a direction opposite to that of the display light through the light guide unit50, the external light is restricted from being reflected on the display surface44and visually recognized together with the display light. Therefore, the image projection unit19is particularly suitable for use in the HUD device100.

In addition, the projection lens30is tilted so as to align the radial direction DD with the tilted image display panel40. According to the inclination of both of the projection lens30and the image display panel40, since there is no angular difference of the placement, an interference between the projection lens30and the image display panel40is restricted, and a dead space can be restricted from occurring between the projection lens30and the image display panel40. Therefore, since an increase in the size of the image projection unit19can be restricted, the mountability of the HUD device100on the vehicle1can be improved.

Second Embodiment

As illustrated inFIGS. 10 to 13, a second embodiment according to the present disclosure is a modification of the first embodiment. A description will be given of the second embodiment, centered on features which differ from those in the first embodiment.

In an illumination light source unit210according to the second embodiment, as shown inFIGS. 10 and 11, multiple light emitting devices12are arrayed in a lattice pattern with one direction on a mounting surface11aas an array direction. In the aligning direction, the number of aligned light emitting devices12is, for example, 1×3, that is, three in total.

In the present embodiment, a normal direction to the planar mounting surface11aof the light source circuit board11is defined as a z-direction. Among directions along the mounting surface11a, a direction in which the number of aligned light emitting devices is large, that is, the direction of aligning three light emitting devices is defined as an x-direction, and a direction in which the number of aligned light emitting devices is small, that is, the direction of aligning one light emitting device (in the present embodiment, a direction in which the light emitting devices are not substantially aligned) is defined as a y-direction.

As in the first embodiment, the respective light emitting devices12are located such that a light emission peak direction PD1is aligned with the z-direction. As in the first embodiment, an optical axis OA of the illumination light source unit210is defined as an axis that passes through a middle light emitting device12located at the center of the illumination light source unit210and extends along the z-direction that is the light emission peak direction PD1.

As in the first embodiment, in the condenser lens220, the convex lens elements22of the same number as that of the light emitting devices12are provided. In other words, a total of 1×3, that is, three convex lens elements22are aligned.

In the condenser lens220, an incident side surface20ahas a single plane similar to that of the first embodiment. On the other hand, light condensing surfaces223provided for the respective convex lens elements22, individually, are aligned on an emission side surface20bof the condenser lens220.

The respective light condensing surfaces223are aligned and placed as in the first embodiment, but a detailed shape of the condensing surfaces223is different from that of the first embodiment. More specifically, the respective light condensing surfaces223are anamorphic surfaces which are different in the radius of curvature in the x-direction and the radius of curvature in the y-direction from each other. In the present embodiment, the radius of curvature in the x-direction is smaller than the radius of curvature in the y-direction at the surface vertex23aof each light condensing surface223and in the vicinity of the surface vertex23a. In this example, the vicinity of the surface vertex23ain the present embodiment means, for example, that a distance from the surface vertex23ais an approximately half value of the diameter of the light condensing surface223.

In more detail, in the xz cross section, each light condensing surface223is formed in a parabolic shape (refer toFIG. 11). On the other hand, in the yz cross section, each light condensing surface223is formed in an arc shape (in particular, in a semicircular shape in the present embodiment) (refer toFIG. 10).

As in the first embodiment, the projection lens230is configured by a lens array in which multiple deflection elements30bmade of light transmissive synthetic resin or glass or the like are aligned and formed integrally, and has a substantially plate-like shape as a whole. Further, in the projection lens230, the divided blocks30asimilar to those in the first embodiment can be defined. In particular, according to the present embodiment, a total of 1×3, that is, three divided blocks30awhich are divided corresponding to the number of aligned light emitting devices12in the x-direction along which the light emitting devices12are aligned can be defined.

As in the first embodiment, the image display panel40is tilted so that the longitudinal direction LD along the x-direction is orthogonal to the optical axis OA and the short direction SD is tilted relative to the optical axis OA in the tangential directions TD to the display surface44. The projection lens230is also tilted corresponding to the image display panel40. When the interval between the image display panel40and the projection lens230is kept constant, the image display panel40and the projection lens230are located in parallel to each other. Furthermore, in the second embodiment, the condenser lens220and the projection lens230partially overlap with each other in a vertical direction perpendicular to the optical axis OA (y-direction on the yz cross section in the present embodiment). This is because one end of the projection lens230is located in a lateral space of the light condensing surface223due to the tilted placement of the projection lens230.

In the second embodiment, a shape of the projection lens230is not particularly coincident with the above tilted placement. Hereinafter, the shape of the projection lens230will be described in detail.

As shown inFIG. 12, on the incident side surface32of the projection lens230, the multiple divided lens surfaces33are formed as components of the deflection elements30bin a state of being divided into stripes so as to be coincident with the boundaries between the adjacent deflection elements30b. A dividing direction of the divided lens surfaces33on the incident side surface32is along the short direction SD inclined, for example, by about 10 to 25 degrees from the y-direction. Therefore, in the xz cross section, one divided lens surface33is formed across the deflection element30band the divided block30a.

In the present embodiment, divided convex surfaces233cdivided into a convex Fresnel lens shape are provided as the divided lens surfaces33. The divided convex surfaces233care formed based on one virtual convex curved surface Svc defined as a virtual lens surface in the projection lens230. In this example, the virtual convex curved surface Svc has a smooth cylindrical surface shape which is curved into a convex shape convexed toward the condenser lens220side in the yz cross section. Therefore, the incident side surface32is mainly configured to deflect the traveling direction of the illumination light in the yz cross section. With the provision of steps in the boundary between the divided convex surfaces233c, the projection lens230is kept substantially in a plate-like shape.

Further, as shown inFIG. 13, although the number of divided blocks30aon the emission side surface34in the projection lens230is reduced corresponds to the number of aligned light emitting devices12, the configuration in each divided block30ais the same as that in the first embodiment.

In each divided block30a, portions on the divided convex surfaces233cand portions on the approximate planes35acorresponding to the surface vertices of the virtual convex curved surfaces Svc and Svb are aligned substantially with the straight line SL extending along the optical axis OA toward the projection lens230side from the surface vertices23aof the corresponding light condensing surfaces223in the condenser lens220.

Also, in the second embodiment described above, since the projection lens230is tilted so that the radial direction DD is aligned with the tangential direction TD of the display surface44, the operation and effects according to the first embodiment can be obtained.

Further, according to the second embodiment, since the condenser lens220and the projection lens230partially overlap with each other in the vertical direction perpendicular to the optical axis OA, a dead space between the condenser lens220and the projection lens230can be reduced.

Third Embodiment

As illustrated inFIGS. 14 and 15, a third embodiment according to the present disclosure is a modification of the first embodiment. A description will be given of the third embodiment, centered on the points which differ from the first embodiment.

Similarly to the first embodiment, a projection lens330according to the third embodiment is aligned with an inclined placement. Hereinafter, the shape of the projection lens330will be described in detail.

On an incident side surface32of the projection lens330which faces a condenser lens20, multiple divided lens surfaces33are formed as components of deflection elements30bin a state of being divided into stripes so as to be coincident with the boundaries between the adjacent deflection elements30b. As in the first embodiment, a dividing direction of the divided lens surfaces33on the incident side surface32extends along a short direction SD inclined, for example, by about 10 to 25 degrees from a y-direction. Each divided lens surface33is placed so that the component of a normal direction to the divided lens surface33in a yx cross section extends along an optical axis OA. The incident side surface32is mainly configured to deflect the traveling direction of the illumination light in the yz cross section.

On the other hand, on an emission side surface34of the projection lens330which faces an image display panel40, multiple divided lens surfaces35are formed as components of the deflection elements30bin a state of being divided into stripes so as to be coincident with the boundaries between the deflection elements30b. As in the first embodiment, the dividing direction of the divided lens surfaces35in the emission side surface34is aligned with the longitudinal direction LD (that is, the x-direction). Each divided lens surface35is placed so that the component of the normal direction to the divided lens surface33in the xz cross section extends along the optical axis OA. The emission side surface34is mainly configured to deflect the traveling direction of the illumination light in the xz cross section.

In the projection lens330according to the third embodiment, among the divided lens surfaces33and35, the approximate planes33aand35aaccording to the first embodiment are replaced by convex curved surfaces333dand335dwhich are curved in the convex shape.

The convex curved surfaces333dand335dare formed based on the virtual convex curved surfaces Sva and Svb defined as the virtual lens surfaces in the projection lens330. In this example, the virtual convex curved surfaces Sva and Svb are the same as those in the first embodiment. The convex curved surfaces333dand335ddo not approximate the virtual convex curved surfaces Sva and Svb, but parts of virtual convex curved surfaces Sva and Svb are extracted as they are, and appear on the incident side surface32and the emission side surface34.

Since the two approximate planes33aor35ain the first embodiment are replaced by one convex curved surface333dor335dat the positions corresponding to the surface vertices of the virtual convex curved surfaces Sva and Svb, the division width Wa is twice the other divided regions.

The radius of curvature Rv of the virtual convex curved surface Svb on the emission side surface34is set to be substantially equal among the divided blocks30a. Therefore, the emission side surface34has substantially the same shape for each of the divided blocks30awhich are divided into five pieces according to the number of aligned light emitting devices12corresponding to the x-direction.

On the other hand, the incident side surface32is configured with a different shape for each of the divided blocks30awhich are divided into three pieces according to the number of aligned light emitting devices12corresponding to the x-direction. In detail, the radius of curvature Rv of the virtual convex curved surface Sva on the incident side surface32is different among the divided blocks30a. In particular, in the present embodiment, the radius of curvature Rv of the virtual convex curved surface Sva of each divided block30achanges step by step so as to be smaller from a short distance side of the tilted projection lens330where a distance from the illumination light source unit10is short toward a long distance side of the tilted projection lens330where the distance from the illumination light source unit10is a long distance. In other words, the radius of curvature of each convex curved surface333dvaries to decrease step by step from the short distance side to the long distance side. Therefore, the gradient of the convex curved surface333dis different for each of the divided blocks30a, and the gradient of the convex curved surface333din the divided block30aon the long distance side is relatively large as compared with the gradient on the short distance side.

As in the first embodiment, the gradient of the anisotropic deflection plane33bis set to be substantially equal in each divided block30a.

Similarly, in the third embodiment described above, since the projection lens330is tilted so that the radial direction DD is aligned with the tangential direction TD of the display surface44, the operation and effects according to the first embodiment can be obtained.

Further, according to the third embodiment, the projection lens30includes the convex curved surfaces333dand335dthat are curved in the convex shape as components of the deflection element30b. Since the illumination light incident on the convex curved surfaces333dand335dis subjected to the condensing action, the restriction of an increase in the size of the HUD device100and suitable illumination for the tilted image display panel40can be realized.

In addition, according to the third embodiment, the radiuses of curvature Rv1to Rv3of the convex curved surfaces333dgradually change from the short distance side to the long distance side of the projection lens330. In this way, each illumination light having passed through each of the convex curved surfaces333dis subjected to the condensing action having a different degree depending on the distance from the illumination light source unit10. Therefore, even when the distances from the illumination light source unit10are different at the respective positions of the projection lens330, the preferable illumination for the tilted image display panel40can be realized.

Other Embodiments

Hereinbefore, multiple embodiments of the present disclosure are described. However, the present disclosure is not interpreted to be limited to the embodiments, and various embodiments and combinations thereof may be applied within a scope which does not depart from the gist of the present disclosure.

Specifically, as a modification 1, as shown inFIG. 16, the light emitting device12may be eccentric to a center side of the illumination light source unit10with respect to the array pitch of the convex lens elements22. In that case, the amount of eccentricity of each light emitting device12may be set asymmetrically across the center light emitting device12.

As a modification 2, instead of making the average value of the deflection amount of the deflection element30blocated on the short distance side of the projection lens30different from the average value of the deflection amount of the deflection element30blocated on the long distance side, or in combination with the different average values, as shown inFIG. 17, the light emitting devices12are not aligned in a straight line, but may be aligned with the position of the composite focal point of the convex lens elements22and the divided blocks30a. In an example ofFIG. 17, the light source circuit board11is configured by a flexible substrate having a mounting surface11awith a wavy warped curved surface, and the multiple light emitting devices12are arrayed in a wavy warped shape. Therefore, the light emitting devices12may be placed asymmetrically with respect to the center.

As a modification 3, as shown inFIG. 18, no condenser lens20may be provided.

As a modification 4 of the first and third embodiments, as shown inFIG. 18, the radius of curvature Rv of the virtual convex curved surface Sva of each divided block30agradually increases from the short distance side toward the long distance side. In an example ofFIG. 18, when it is assumed that the radius of curvature is set to Rv1, Rv2, and Rv3in order from the divided block30aon the short distance side, Rv1>Rv2>Rv3is satisfied. A magnitude relationship of the radii of curvature Rv on the short distance side and the long distance side can be changed depending on design conditions such as presence or absence of the condenser lens20, and a focal length and placement of the condenser lens20.

As a modification 5, the division width may be set so that the sag amount of the respective divided lens surfaces33and35is kept substantially constant. Further, the number of divided lens surfaces33and35on each of the surfaces32and34or the number of arrayed deflection elements30bcan be arbitrarily set.

As a modification 6, instead of making the average value of the deflection amount of the deflection element30blocated on the short distance side of the projection lens30different from the average value of the deflection amount of the deflection element30blocated on the long distance side, or in combination with the different average values, a direction from the surface vertex of the virtual convex curved surface Sva toward the center of curvature may be different between the short distance side and the long distance side.

In Modification 7 of the first embodiment, as long as the approximate plane33ais formed in a planar shape by partial approximation of the virtual convex curved surface Sva, for example, the approximate plane33may be formed by, for example, extracting a tangential plane of the virtual convex curved surface Sva at a midpoint of the divided region.

As a modification 8, the light condensing surface23may be formed in a spherical shape.

As a modification 9, the projection lens30may have a shape in which the shapes of the incident side surface32and the emission side surface34are interchanged with each other.

As a modification 10, the projection lens30may have a slight angular difference from the image display panel40as long as the projection lens30is tilted so as to align the radial direction DD with the tangential direction TD of the display surface44.

In a modification 11, the projection lens30may not include the multiple deflection elements30baligned along the radial direction DD. Specifically, even if the convex lens has a single lens surface on each of the incident side surface32and the emission side surface34, if the radius of curvature of the lens surface is set to be large, the present disclosure can be applied to such a configuration.

In Modification 12, the present disclosure may be applied to various mobile objects (transportation equipment) such as vessels or aircraft other than the vehicle2.

The head-up display device described above is mounted on the mobile object1and projects display light of an image on the projection member3to virtually display the image in such a manner as to be visible to the occupant. The head-up display device includes the illumination light source units10and210, the image display panel40, and the projection lenses30,230, and330. The illumination light source units10and210emit the illumination light. The image display panel40causes the illumination light from the illumination light source unit side to pass through the image display panel40and to be emitted as a display light from the display surface44as the display light to display the image. The projection lenses30,230, and330are located between the illumination light source unit and the image display panel, and projects the illumination light from the illumination light source unit side onto the image display panel. The image display panel is tilted so that the normal direction ND to the display surface intersects with the optical axis OA of the illumination light source unit. The projection lens is tilted so that the radial direction DD of the projection lens is aligned with the tangential direction TD to the display surface.

According to the above disclosure, in the image display panel, the normal direction to the display surface is deviated from the optical axis. In addition, the projection lens is tilted so as to align the radial direction with the tilted image display panel. According to the inclination of both of the projection lens and the image display panel, since there is no angular difference of the placement, an interference between the projection lens and the image display panel is restricted, and a dead space can be restricted from occurring between the projection lens and the image display panel. Therefore, the HUD device having high mountability on the movable object, which is capable of restricting an increase in the size of the HUD device can be provided.

The head-up display device100described above is mounted on the mobile object1and projects display light of an image on the projection member3to virtually display the image in such a manner as to be visible to the occupant. In the head-up display device100, the image projection unit19projects the display light onto the light guide unit50that guides the display light to the projection member. The image projection unit19includes the illumination light source units10and210, the image display panel40, and the projection lenses30,230, and330. The illumination light source units10and210emit the illumination light. The image display panel40causes the illumination light from the illumination light source unit side to pass through the image display panel40and to be emitted as a display light from the display surface44as the display light to display the image. The projection lenses30,230,330are located between the illumination light source unit and the image display panel, and project the illumination light from the illumination light source unit side onto the image display panel. The image display panel is tilted so that the normal direction ND to the display surface intersects with the optical axis OA of the illumination light source unit. The projection lens is tilted so that the radial direction DD of the projection lens is aligned with the tangential direction TD to the display surface.

Further, according to the above embodiment, the image projection unit having the image display panel in which the normal direction to the display surface intersects with the optical axis projects the display light onto the light guide unit. According to the image projection unit configured as described above, even when an external light such as sunlight enters the image display panel in a direction opposite to that of the display light through the light guide unit, the external light is restricted from being reflected on the display surface and visually recognized together with the display light. Therefore, the image projection unit is particularly suitable for use in the HUD device.

In addition, the projection lens is tilted so as to align the radial direction with the tilted image display panel. According to the inclination of both of the projection lens and the image display panel, since there is no angular difference of the placement, an interference between the projection lens and the image display panel is restricted, and a dead space can be restricted from occurring between the projection lens and the image display panel. Therefore, since an increase in the size of the image projection unit can be restricted, the mountability of the HUD device on the movable object can be improved.

The present disclosure has been described based on the embodiments; however, it is understood that this disclosure is not limited to the embodiments or the structures. The present disclosure includes various modification examples and modifications within the equivalent range. In addition, it should be understood that various combinations or aspects, or other combinations or aspects, in which only one element, one or more elements, or one or less elements are added to the various combinations or aspects, also fall within the scope or technical idea of the present disclosure.