JP2011209616A - Method for manufacturing head-up display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a head-up display device that can be reduced in size while minimizing an increase of its manufacturing cost.SOLUTION: The head-up display device 1 includes: a display device 5 for displaying an image 80; a concave mirror 6 having a reflecting face 6a for enlarging and reflecting the image 80; and a lens 7 having an incident-side end face 7a for enlarging the reflection image 81 reflected by the concave mirror 6, and used to project the enlargement image 82, enlarged and transmitted by the incident-side end face 7a, onto an image projecting surface part 9a. The shape of the incident-side end face 7a of the lens 7 is uniquely determined in the step S10 of determining an incident-side end face shape. Thereafter, the shape of a reflecting face 6a is determined in the step S20 of determining the shape of a reflecting face. The reflecting face 6a is determined into such a shape that distortion of a virtual image 4a, displayed when the image 80 of the display device 5 passing through the lens 7 is projected onto the image projecting surface part 9a, is corrected.

Description

  The present invention relates to a method for manufacturing a head-up display device mounted on a vehicle.

  2. Description of the Related Art Conventionally, a vehicle head-up display device that is mounted on a vehicle and displays a virtual image of the image inside the vehicle by projecting an image onto an image projection surface of a windshield is known.

  The head-up display device mounted on such a vehicle is often installed in a space provided inside the instrument panel. Inside the instrument panel, a combination meter, air duct for air conditioner, etc. are installed, and a vehicle with a relatively small instrument panel such as a small car has enough space to install a head-up display device. It may be difficult.

  In view of this, a head-up display device has been proposed that includes a lens having a further magnifying function between a concave mirror having a magnifying function and a windshield (see Patent Document 1). By providing a lens having an enlargement function, a smaller display can be employed, and the head-up display device can be downsized.

JP 2008-268883 A

  Although the shape of the windshield is symmetric with respect to the vehicle width direction at the center of the vehicle, the image emitted from the head-up display device is generally projected in front of the driver. Therefore, the image projection surface portion of the windshield onto which the image is projected becomes a free curved surface that is asymmetric with respect to the vehicle width direction. In addition, since the shape of the windshield is different for each vehicle type, the shape of the image projection surface portion is also different for each vehicle type.

  On the other hand, a concave mirror having an enlargement function has a problem specific to its shape. The problem is that both ends of the enlarged image are distorted. As the magnification of the concave mirror increases, the distortion around the image increases. In addition, as with a concave mirror, a lens having an enlargement function increases the distortion around the image as the enlargement ratio is increased.

  As described above, the complicated shape of the windshield further distorts the image distorted by the concave mirror and the lens.

  For these reasons, in order to finally improve the display state of the virtual image, it is necessary to determine the optimum shape of the concave mirror and the lens in accordance with the shape of the windshield that differs for each vehicle type. If the optimal shape is determined in the dark clouds by trial and error in this way, the situation arises that the shape of the concave mirror and lens becomes complicated, or the concave mirror and lens must be prepared for each vehicle type. In particular, a situation where the shape of the lens is complicated or a vehicle must be prepared for each vehicle type greatly increases the manufacturing cost of the head-up display device.

  The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a method for manufacturing a head-up display device that can achieve downsizing while suppressing an increase in manufacturing cost as much as possible.

According to a first aspect of the present invention, there is provided a method for manufacturing a head-up display device for a vehicle which is mounted on a vehicle and displays a virtual image of the image in the vehicle by projecting the image onto the image projection surface of the windshield. The head-up display device has a display for displaying an image, a concave mirror having a reflecting surface that magnifies and reflects the image, and an incident surface that magnifies the reflected image of the image reflected by the reflecting surface, A lens that projects a magnified image that has been magnified and transmitted on the incident surface onto the image projection surface, and
An incident surface shape determining step for uniquely determining the shape of the incident surface, and a virtual image displayed when an image transmitted through a lens having a uniquely determined incident surface is projected on the image projection surface portion after the incident surface shape determining step. A reflection surface shape determination step for determining the shape of the reflection surface so that the distortion of the reflection surface is corrected.

  In the present invention, the shape of the incident surface of the lens determined in the incident surface determination step is uniquely determined. For this reason, for example, the shape of the incident surface can be made such that the manufacturing efficiency is high and the increase in manufacturing cost can be suppressed as much as possible regardless of the shape of the image projection surface portion of the windshield. In addition, since the shape of the entrance surface of the lens can be freely determined for the convenience of the manufacturer, it is possible to use a common lens instead of preparing a lens for each vehicle type. Thus, by uniquely determining the shape of the entrance surface of the lens, an increase in the cost of the lens can be suppressed.

  Further, according to the present invention, reflection is performed so that distortion of a virtual image displayed when an image displayed on a display that transmits a lens having a uniquely defined incident surface shape is projected onto an image projection plane is corrected. Since the surface shape is determined in the reflecting surface shape determining step, the reflecting surface shape tends to be a complicated shape as compared with the incident surface shape. However, since this complicated surface is formed on the reflecting surface, an increase in manufacturing cost can be minimized as compared with the case where it is formed on the incident surface of the lens.

  Therefore, according to the manufacturing method of the present invention, it is possible to provide a head-up display device that can achieve downsizing while suppressing an increase in manufacturing cost as much as possible.

  Specifically, as described in claim 2, since the shape of the incident surface uniquely determined in the incident surface shape determination step is symmetric with respect to the vehicle width direction, the shape of the incident surface can be simplified. It will be something.

  Further, the incident surface that is symmetric with respect to the vehicle width direction has a direction along the optical axis of the lens as the γ direction, and is orthogonal to the γ direction, as described in claim 3, The direction along the direction α, the direction γ and the direction orthogonal to the α direction are the β direction, the coordinates in the γ direction are γ, the coordinates in the α-β plane are (α, β), and the incident surface of the lens is When a polynomial expressed by γ = f (α, β) is used, the lens has an enlargement function because it is a free-form surface expressed by a polynomial other than a term in which the degree of α is an odd number. It is possible to simplify the shape of the incident surface while providing the same.

  In particular, as described in claim 4, if the shape of the image projection surface portion of the windshield on which the image is projected is a free-form surface shape that is asymmetric with respect to the vehicle width direction, the distortion of the virtual image is corrected. The shape of the concave mirror tends to be complicated. The present invention functions particularly effectively in the case where the shape of the image projection surface portion is a free-form surface that is asymmetric with respect to the vehicle width direction.

1 is a schematic configuration diagram illustrating a vehicle head-up display device (HUD device) to which the present invention is applied. It is an enlarged view of the principal part of the HUD apparatus of FIG. It is a perspective view of a cylindrical lens single-piece | unit. It is explanatory drawing which shows the influence by attaching a cylindrical lens in the state of off-axis. It is a perspective view of a concave mirror simple substance. It is explanatory drawing which shows the influence by having attached the concave mirror off-axis. It is a flow explaining the process of determining the shape of the incident side end surface of the cylindrical lens of a head-up display apparatus, and the reflective surface of a concave mirror.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a vehicle head-up display device (HUD device) to which the present invention is applied. FIG. 2 is an enlarged view of the main part.

  As shown in FIG. 1, the HUD device 1 is arranged inside an instrument panel (hereinafter referred to as instrument panel) 2 that extends from the lower edge of the front windshield 9 toward the vehicle interior side, and displays various information as an image 80. Display device 5, a concave mirror 6 that magnifies and reflects an image 80 displayed on the display device 5, and a magnified image 82 that magnifies and transmits a reflected image 81 reflected by the concave mirror 6 toward the front windshield 9. An outgoing cylindrical lens 7 is provided.

  The enlarged image 82 that has passed through the cylindrical lens 7 is reflected by the image projection surface portion 9a of the front windshield 9 and reaches the eye range 3 of the vehicle occupant. As a result, the occupant sees the virtual image 4 of the enlarged image 82 so as to overlap the foreground of the vehicle (on the opposite side of the occupant across the front windshield 9).

  Here, the image projection surface portion 9 a is a part provided in a part of the front windshield 9, and when a frame-like image along the outermost peripheral edge portion of the screen of the display device 5 is projected onto the front windshield 9. It is a part inside the frame-like virtual image 4 to be displayed.

  Since the HUD device 1 has a cylindrical lens 7 having an enlargement function disposed between the front windshield 9 and the concave mirror 6 in addition to the concave mirror 6 having an enlargement function, the display device 5 can be downsized. As a result, downsizing of the HUD device 1 is promoted.

  In addition, the instrument panel 2 has an opening in the upper surface of the instrument panel 2, and a cylindrical light guide 2a for guiding the reflected image 81 reflected by the concave mirror 6 to the front windshield 9 is formed. The cylindrical lens 7 is disposed so as to block the light guide portion 2a. That is, the cylindrical lens 7 also serves as a cover for dust-proofing the inside of the instrument panel 2 by closing the opening of the light guide portion 2a.

  However, the instrument panel 2 (including the inner wall forming the light guide portion 2a) is formed of a light shielding resin. That is, the light incident on the upper surface of the instrument panel 2 and the inner wall forming the light guide 2a is configured to be absorbed without being reflected.

  In the following, the traveling direction of the main optical axis 8 of the enlarged image 82 that passes through the light guide 2a (transmits through the cylindrical lens 7) is the Z direction, the vehicle width direction of the vehicle (the horizontal direction of the virtual image 4) is the X direction, and the X direction. A direction perpendicular to both the Z direction and the Z direction is referred to as a Y direction.

  Further, as shown in FIG. 2, a surface of the concave mirror 6 that reflects the image 80 projected from the display device 5 is referred to as a reflective surface 6 a, and a reflected image 81 of the cylindrical lens 7 that is reflected by the reflective surface 6 a. Is referred to as the incident side end face 7a, and the surface from which the transmitted enlarged image 82 is emitted is referred to as the transmissive face 7b.

<Front windshield>
The front windshield 9 has a free-form surface and is inclined toward the rear of the vehicle as shown in FIG. The curvature of the free-form surface is not uniform and is partially different. That is, the front windshield 9 is symmetric with respect to the vehicle width direction with respect to the vehicle width direction center of the vehicle, and the curvature increases from the vehicle width direction center toward the vehicle side portion. Moreover, the front windshield 9 has an image projection surface part 9a on which a magnified image 82 that is magnified and transmitted by the cylindrical lens 7 is projected.

Here, the image projection surface portion 9a has the γ direction as the thickness direction of the front windshield 9, the α direction as the direction along the vehicle width direction, the coordinates in the β direction and the γ direction as the directions orthogonal to the γ direction and the α direction, respectively. Is expressed as a polynomial f _W (α, β) as shown in the following equation (Equation 1), where γ is the coordinate in the α-β plane. In this equation, w _n (coefficient) of each term includes 0 “zero”. In the present embodiment, the image projection surface portion 9a of the front windshield 9 is expressed by a fourth-order polynomial, but it may be a fifth-order or higher polynomial.

画像投影面部９ａは、車幅方向中央より運転席側、本実施形態では車両前方に向って右側に位置している。このため、画像投影面部９ａの形状は、車幅方向に対して非対称な自由曲面形状となる。すなわち、この画像投影面部９ａは、車幅方向および鉛直方向において、車両後方に向って傾いており、車幅方向において、当該面部９ａ中央より右側の曲率が左側の曲率に比べ大きくなる。なお、上記数式１にて表される画像投影面部９ａの係数Ｗ_ｎは車種（サルーンタイプ、スポーツタイプ、バス・トラック）や車体の大きさによって変わる。どのような車種であっても、また車体の大きさが異なっていても、画像投影面部９ａは、右側に向うに連れて曲率が大きくなっているため、画像投影面部９ａに拡大画像８２を投影すると、その像は左側よりも右側の方が大きく歪むこととなる。

The image projection surface portion 9a is located on the right side of the driver seat side from the center in the vehicle width direction, in this embodiment, toward the front of the vehicle. For this reason, the shape of the image projection surface portion 9a is a free-form surface that is asymmetric with respect to the vehicle width direction. That is, the image projection surface portion 9a is inclined toward the rear of the vehicle in the vehicle width direction and the vertical direction, and the curvature on the right side of the center of the surface portion 9a is larger than the curvature on the left side in the vehicle width direction. Note that the coefficient W _n of the image projection surface portion 9a expressed by Equation 1 varies depending on the vehicle type (saloon type, sports type, bus / truck) and the size of the vehicle body. Regardless of the type of vehicle and the size of the vehicle body, since the curvature of the image projection surface portion 9a increases toward the right side, the enlarged image 82 is projected onto the image projection surface portion 9a. As a result, the image on the right side is more distorted than on the left side.

<Cylindrical lens>
The cylindrical lens 7 is a well-known lens in which only one direction acts as a lens (enlarges in the present embodiment) out of directions orthogonal to the lens thickness direction (light transmitting direction).

  FIG. 3 is a perspective view of the cylindrical lens 7 alone. As shown in FIG. 3, the cylindrical lens 7 has a rectangular flat surface 70, one of the two surfaces located at both ends in the γ direction, and the other surface having a curved surface of a part of a cylinder. The formed lens forming surface 71 is formed. In addition, the cylindrical lens 7 has a shape in which the intersecting line with the flat surface 70 and the intersecting line with the lens forming surface 71 are parallel to each other in the section orthogonal to the α direction (that is, the section has a rectangular shape). Have.

The lens forming surface 71 is a uniquely defined surface, the thickness direction of the lens 7 is the γ direction, the direction along the vehicle width direction is the α direction, the direction orthogonal to the γ direction and the α direction is the β direction, When the coordinate in the γ direction is γ and the coordinate in the α-β plane is (α, β), it is expressed by a polynomial f ₁ (α, β) as shown in the following equation (Equation 2). Note that, in this formula, l _n of the respective terms _{(coefficients)} comprises 0 "zero". In this embodiment, the lens forming surface 71 is expressed by a fourth-order polynomial, but it may be a fifth-order or higher polynomial. In the case of the cylindrical lens 7, the coefficient of the term including β is 0 “zero”. In this cylindrical lens 7, the α direction is a direction (acting axis direction) that acts as a lens, and the β direction is a direction that does not act as a lens (non-acting axis direction).

  In the cylindrical lens 7 having the lens forming surface 71 represented by the above mathematical formula, the free-form surface is symmetrical with respect to the α direction with respect to the center of the α direction of the lens 7. In addition, the lens forming surface 71 of the present embodiment is represented by a polynomial composed of terms excluding the term in which the degree of α is an odd number, as shown in the above formula 2. The lens 7 having such a lens forming surface 71 has a very simple shape as compared with a lens represented by a polynomial including a term in which the order of α is an odd number. The rise can be suppressed. The lens is usually formed by cutting out from a base material having translucency. For this reason, the more complicated the shape of the lens forming surface 71, the higher the manufacturing cost may be. Depending on the shape, the thickness of the lens may increase.

  As shown in FIG. 2, the cylindrical lens 7 has the lens forming surface 71 as the incident side end surface 7 a, the flat surface 70 as the transmission surface 7 b, and the action axis direction (α direction) of the cylindrical lens 7 is the vehicle width direction (virtual image 4). In the direction of the main optical axis 8 of the enlarged image 82 with respect to the thickness direction (γ direction) of the cylindrical lens 7 and the Y direction with respect to the β direction are inclined by an inclination angle θx. It is attached to the position of the installation depth d from the opening of the light guide 2a.

  As shown in FIG. 2, since the cylindrical lens 7 is installed with the optical axis of the lens 7 and the main optical axis 8 off-axis, as shown in FIG. The virtual image 4a when the image 80 is directly projected on the lens 7 without going through 6 is shown in FIG. 4B by the optical action of the free-form surface of the incident side end surface 7a of the lens 7 described above. As shown, the center part of the virtual image 4a is distorted so as to protrude upward in the vertical direction. The distortion of the virtual image 4a can be adjusted by changing the inclination angle θx as well as the shape of the free-form surface of the incident side end face 7a.

  Further, since the image projection surface portion 9a of the front windshield 9 has a free curved surface shape that is asymmetric in the vehicle width direction as described above, and the curvature increases toward the right side, as shown in FIG. As shown, the right side of the virtual image 4a is distorted more than the left side. Such distortion of the image in the vehicle width direction due to the shape of the image projection surface portion 9a can be corrected by setting the free-form surface shape of the incident side end surface 7a of the cylindrical lens 7, but in the present embodiment, Since the incident-side end surface 7a has a free-form surface symmetrical with respect to the α direction with respect to the center of the lens 7, image distortion in the vehicle width direction cannot be corrected. Therefore, the virtual image 4a projected onto the image projection surface portion 9a via the lens 7 is affected by the free-form surface shape of the image projection surface portion 9a as shown in FIG. It becomes.

<Concave mirror>
FIG. 5 is a perspective view of the concave mirror 6 alone. The concave mirror 6 has a reflecting surface 6a that reflects light. The reflecting surface 6a has an optical axis direction of the concave mirror 6 as the γ direction, two directions orthogonal to the γ direction, α direction and β direction, γ direction coordinates as γ, and α-β plane coordinates as (α, β). In this case, it is expressed by a polynomial f _m (α, β) as shown in the following equation (Equation 3). In this equation, m _n (coefficient) of each term includes 0 “zero”. On the reflecting surface 6a, the coefficient _{mn of the following} formula is determined so that the distorted virtual image 4a as shown in FIG. 4B becomes the virtual image 4 with the distortion corrected as shown in FIG. In the present embodiment, the reflecting surface 6a is expressed by a fourth-order polynomial, but it may be a fifth-order or higher polynomial.

凹面鏡６は、図２に示すように、α方向が車幅方向（虚像４の水平方向）と一致し、凹面鏡６のγ方向に対する拡大画像８２の主光軸８の進行方向（Ｚ方向）およびβ方向に対するＹ方向が傾斜角度θｍだけ傾斜した状態で、しかも、凹面鏡６の中心で反射した光が、シリンドリカルレンズ７の中心を透過するような位置に設置される。

As shown in FIG. 2, the concave mirror 6 has the α direction coincident with the vehicle width direction (horizontal direction of the virtual image 4), the traveling direction (Z direction) of the main optical axis 8 of the enlarged image 82 with respect to the γ direction of the concave mirror 6, and In the state where the Y direction with respect to the β direction is inclined by the inclination angle θm, the light reflected at the center of the concave mirror 6 is installed at a position where it passes through the center of the cylindrical lens 7.

  As shown in FIG. 2, since the concave mirror 6 is installed with the optical axis of the concave mirror 6 and the main optical axis 8 off-axis, as shown in FIG. As shown in FIG. 6 (b), the virtual image 4b when the image 80 is directly projected onto the concave mirror 6 without passing through the optical action of the free-form surface shape of the reflecting surface 6a of the concave mirror 6 described above, The center part of the virtual image 4b is distorted so as to protrude downward in the vertical direction.

  In this embodiment, the virtual image 4b is intentionally distorted so that the distortion of the virtual image 4b generated by the cylindrical lens 7 and the front windshield 9 shown in FIG. 4B becomes the virtual image 4 shown in FIG. Not. The distortion of the virtual image 4b can be adjusted by changing the inclination angle θm as well as the shape of the free-form surface of the reflecting surface 6a.

  As described above, since the cylindrical lens 7 and the concave mirror 6 of the HUD device 1 are formed, the driver can correct the distortion when the enlarged image 82 is projected on the image projection surface portion 9a of the front windshield 9. The virtual image 4 can be visually recognized.

  As above, the front windshield 9, the cylindrical lens 7 of the HUD device 1, and the concave mirror 6 have been described with respect to the portions that generate optical effects. Next, the manufacturing procedure of the cylindrical lens 7 will be described with reference to FIG.

  As shown in FIG. 7, the free curved surface shapes of the incident side end surface 7a and the reflecting surface 6a are determined through an incident side end surface shape determining step S10 and a reflecting surface shape determining step S20.

  First, in the incident side end surface shape determining step S10, the free curved surface shape of the incident side end surface 7a is determined. The incident side end face 7a has a unique shape as described above. In the present embodiment, an enlargement ratio that is symmetric with respect to at least the α direction and that allows the virtual image 4 having a desired size to be obtained when the enlarged image 82 that has passed through the cylindrical lens 7 is projected onto the image projection surface portion 9a. It has a feasible shape. That is, the shape of the incident-side end surface 7a is not determined in consideration of correction of distortion caused by the image projection surface portion 9a being asymmetric with respect to the vehicle width direction.

  Next, based on the shape of the incident side end face 7a determined in the above step S10, the free curved surface shape of the reflecting surface 6a is determined in the reflecting surface shape determining step S20. In the present embodiment, the free curved surface shape of the reflecting surface 6a is determined such that the distortion of the virtual image 4a caused by the free curved surface shapes of the cylindrical lens 7 and the front windshield 9 is corrected.

  Then, in the molding step, the cylindrical lens 7 and the concave mirror 6 are molded according to the determined incident-side end surface 7a and reflecting surface 6a. Further, in the assembly process, the cylindrical lens 7 and the concave mirror 6 molded in the molding process and other parts (such as the display device 5) are assembled in the case of the HUD device 1.

  Since the incident side end face 7a and the reflecting surface 6a are determined through the above process, in particular, the incident side end face 7a can be determined in accordance with the convenience of the manufacturer. For example, the increase in the manufacturing cost of the lens can be suppressed as much as possible by using a shape that is symmetrical with respect to the α direction as in the present embodiment. Further, since the incident-side end surface 7a can be determined without considering the shape of the image projection surface portion 9a, the cylindrical lens 7 can be shared even when the free-form surface shape of the image projection surface portion 9a is different. It is. By making the cylindrical lens 7 common, it is possible to further suppress an increase in the manufacturing cost of the HUD device 1 rather than simplifying the shape of the incident side end face 7a.

  According to the determination of the shape of the incident side end surface 7a according to the convenience of the manufacturer, the shape of the reflection surface 6a becomes complicated. However, according to this embodiment, even if the shape of the reflecting surface 6a becomes complicated, the HUD device 1 can be downsized while suppressing an increase in manufacturing cost. The increase in the manufacturing cost of the lens 7 when the shape of the incident side end surface 7a of the cylindrical lens 7 is complicated compared to the increase of the manufacturing cost of the concave mirror 6 when the shape of the reflecting surface 6a is complicated. Because it is very big.

  The cylindrical lens 7 is usually manufactured by cutting a light-transmitting base material or injection-molding a light-transmitting resin material. On the other hand, the concave mirror 6 is manufactured by hot bending of a glass plate or by pressing a metal plate. Compared to the lens 7, the concave mirror 6 is very easy to manufacture. Further, when the shape of the incident side end face 7a is determined by trial and error, the thickness of the lens 7 in the γ direction may have to be increased depending on the shape. On the other hand, since the concave mirror 6 generates an optical action by reflection, the thickness in the γ direction does not increase depending on the shape unlike the lens 7. As described above, the cylindrical lens 7 is more likely to increase the manufacturing cost than the concave mirror 6.

  Therefore, as in this embodiment, by uniquely determining the shape of the incident side end surface 7a of the cylindrical lens 7 so as to be convenient for the manufacturer, it is possible to achieve downsizing while suppressing an increase in manufacturing cost as much as possible. The HUD device 1 can be manufactured.

  Further, as described in the present embodiment, the cylindrical lens 7 and the concave mirror 6 manufactured in this way are very different from those in which the image projection surface portion 9a has an asymmetric shape with respect to the vehicle width direction. Works effectively.

  In the present embodiment, the display device 5 corresponds to the display device described in the claims, and the incident side end surface 7a of the cylindrical lens 7 corresponds to the incident surface described in the claims. Further, the incident side end face shape determining step S10 corresponds to the incident face shape determining step recited in the claims.

(Other embodiments)
In the above, several embodiment of this invention was described. The present invention is not construed as being limited to the above-described embodiments, and can be applied to various embodiments without departing from the scope of the invention. For example, the type of lens for enlarging the reflected image 81 reflected by the concave mirror 6 is not limited to the cylindrical lens 7 and may be a linear Fresnel lens.

  DESCRIPTION OF SYMBOLS 1 Head up display apparatus (HUD apparatus), 2 Instrument panel (instrument panel), 2a Light guide part, 3 Eye range, 4 Virtual image, 4a Virtual image, 4b Virtual image, 5 Display device (display), 6 Concave mirror, 6a Reflecting surface , 7 cylindrical lens, 7a incident side end surface (incident surface), 7b transmission surface, 8 main optical axis, 9 front windshield, 9a image projection surface part, 70 flat surface, 71 lens forming surface, 80 image, 81 reflection image, 82 Enlarged image

Claims (4)

In a method for manufacturing a vehicle head-up display device that is mounted on a vehicle and displays a virtual image of the image in the vehicle by projecting an image onto an image projection surface portion of a windshield.
The head-up display device includes:
A display for displaying the image;
A concave mirror having a reflecting surface for enlarging and reflecting the image;
A lens that has an incident surface that magnifies a reflected image of the image reflected by the reflecting surface, and that projects a magnified image that has been magnified and transmitted through the incident surface onto the image projection surface portion;
An incident surface shape determining step for uniquely determining the shape of the incident surface;
After the incident surface shape determination step, the distortion of a virtual image displayed when the image that has passed through the lens having the uniquely defined incident surface is projected onto the image projection surface portion is corrected. A method for manufacturing a head-up display device for a vehicle, comprising: a reflecting surface shape determining step for determining a shape of the reflecting surface.   The method for manufacturing a head-up display device for a vehicle according to claim 1, wherein the shape of the incident surface uniquely determined in the incident surface shape determination step is symmetric with respect to the vehicle width direction. .   The direction along the optical axis of the lens is the γ direction, orthogonal to the γ direction, the direction along the vehicle width direction is the α direction, the direction orthogonal to the γ direction and the α direction is the β direction, and the γ direction. Γ, the coordinates in the α-β plane are (α, β), and the incident surface of the lens is a polynomial expressed by γ = f (α, β). The vehicle head-up display device according to claim 2, wherein the head-up display device for a vehicle is a free-form surface expressed by a polynomial including a term excluding a term in which the degree of α is an odd number.   4. The vehicle head-up display device according to claim 1, wherein the image projection surface portion has a free-form surface shape that is at least asymmetric with respect to a vehicle width direction of the vehicle. 5. Production method.

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