JP6611310B2 - Projection display device for vehicle - Google Patents

Description

  The present invention relates to a vehicle projection display device that performs display using light reflection of a windshield (window glass) of a vehicle.

  For example, a general vehicle head-up display device (hereinafter referred to as a “HUD device”) uses a front windshield or a combiner (reflector) in the vicinity of the front windshield to display a light image including various information to be displayed. The light path is formed so that the light projected onto the light and reflected by the front windshield or the like is directed toward the driver's viewpoint. Thus, the driver can visually recognize an image projected from the HUD device (hereinafter referred to as “display image”) reflected on the front windshield or the like as a virtual image while visually recognizing the scenery in front of the vehicle. That is, the driver can visually recognize the display image by the HUD device without moving the line of sight while maintaining the normal driving state.

  By the way, in a device that projects a display image on the surface of a windshield or the like, such as a HUD device, distortion may occur in a virtual image visually recognized by the driver. For example, the cause of this distortion is that the driver views the display image projected on the surface of the windshield from an oblique direction, and that the surface of the windshield itself has a gently curved shape. Furthermore, since the curvature and the inclination angle with respect to the horizontal plane (or vertical plane) are different for each windshield location, various distortions may occur in the virtual image depending on the situation. In addition, when a display image is projected using the magnifying optical system, distortion may occur due to curved surface shapes such as lenses and mirrors included in the magnifying optical system. These distortions adversely affect the visibility of the display image.

  Conventionally, among such distortions (aberrations), a three-dimensional distortion of a display image (virtual image) due to “field curvature” has been a major factor for reducing the visibility of the display image.

  In order to reduce such distortion of a three-dimensional display image, the HUD device described in Patent Document 1 (hereinafter referred to as “conventional device”) projects laser light emitted from a laser module onto a windshield or the like. Before the image is projected onto a screen curved in a predetermined shape provided in the middle of the optical system of the HUD device. Thereafter, the light emitted (reflected) from the image projected on the screen (curved image) is projected onto the windshield through a concave mirror or the like. Thus, the conventional apparatus corrects the curvature of field of the virtual image by once forming a curved image on the curved screen.

JP2013-25205A

  As described above, the conventional apparatus employs a screen having a specific shape in the middle of the optical system of the HUD apparatus (on the optical path), thereby displaying “field curvature” caused by the characteristics of the windshield and the like. Three-dimensional distortion of the image (virtual image) is reduced.

  However, in the conventional apparatus, when light is reflected on the surface of the screen, the amount of light scattered and transmitted to the downstream side of the optical path is reduced, so that the light utilization efficiency is poor. Furthermore, when external light such as sunlight is incident on the screen, the visibility of the display image may be reduced due to the external light.

  The present invention has been made in view of the above-described circumstances, and its object is to reduce the curvature of field caused by the shape of the windshield and the like and the optical system of the HUD device without using the screen of the conventional device. Another object of the present invention is to provide a vehicle projection display device capable of improving the visibility of a display image.

In order to achieve the above-described object, the vehicle projection display apparatus according to the present invention has the following features (1) to ( 2 ).
(1)
A projection unit that projects light to be formed as a display image on a display surface formed by a windshield of a vehicle or a light reflecting member in the vicinity of the windshield, and the light projected from the projection unit is displayed. An optical system that leads to a surface, and a vehicular projection display device that makes it possible to visually recognize a virtual image of the display image from a predetermined eye point,
An intermediate image forming optical member that forms an intermediate image having a shape that is at least partially curved using the light projected from the projection unit, and that introduces light emitted from the intermediate image into the optical system;
The optical system includes a concave mirror,
The intermediate image forming optical member is disposed between the projection unit and the concave mirror so that the intermediate image is positioned between the focal point of the concave mirror and the concave surface of the concave mirror ,
The intermediate imaging optical member includes a microlens array;
It is a vehicle projection display device.
(2)
In the vehicle projection display device described in (1) above,
The intermediate image forming optical member is
Forming the intermediate image having a shape for correcting an aberration related to field curvature generated in the virtual image due to the characteristics of at least one of the optical system and the display surface;
It is a vehicle projection display device .

According to the vehicle projection display device having the configuration (1), light emitted from an intermediate image that is at least partially curved (in other words, light derived from an image that is at least partially curved) is introduced into the optical system. Therefore, the curvature of field can be corrected by adjusting the shape of the intermediate image (curved image) in consideration of the curvature of field caused by the shape of the windshield and the like. Furthermore, since it is not necessary to use a screen as in the conventional device, there is no decrease in light utilization efficiency, and a decrease in visibility of a display image due to external light can be avoided.
Furthermore, according to the projection display apparatus for a vehicle having the configuration (1), it is possible to pass light emitted from the intermediate image to the optical system without reducing light transmission efficiency. Therefore, the light use efficiency can be increased.
According to the vehicular projection display device having the configuration (2), the shape of the intermediate image is determined in consideration of the curvature of field caused by the shape of the windshield of the vehicle. The visibility of the display image can be improved.

  According to the vehicle projection display device of the present invention, the curvature of field caused by the shape of the windshield and the optical system of the HUD device can be reduced and displayed without using a special screen as in the conventional device. It is possible to improve the visibility of the image.

  The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

FIG. 1 is a longitudinal sectional view showing the positional relationship of each element when a vehicle equipped with a HUD device is viewed from the side. FIG. 2 is an optical path diagram showing an optical path when no intermediate image forming optical member is present in the vehicle projection display apparatus shown in FIG. FIG. 3 is an optical path diagram showing an optical path when an intermediate image forming optical member is present in the vehicle projection display apparatus shown in FIG. FIG. 4 is an optical path diagram illustrating a configuration and an optical path of the vehicle projection display apparatus according to the embodiment.

  Specific embodiments relating to the vehicle projection display apparatus of the present invention will be described below with reference to the drawings.

<Basic configuration example of a vehicle projection display device>
FIG. 1 shows the positional relationship of each element when a vehicle equipped with a vehicle projection display device (hereinafter referred to as “HUD device 100”) according to this embodiment is viewed from the side.

  The HUD device 100 is housed inside a dashboard (not shown) of a vehicle, and a display image is displayed on a display surface (in this example, a windshield WS) through an opening OP formed in a part of the upper surface of the dashboard. Is configured to project light to be imaged.

  The HUD device 100 includes a display device 10, an intermediate image forming optical member 20, a concave mirror 30, and a display control unit (not shown). The display device 10 has a display surface (a flat shape that is not curved) that can display an arbitrary two-dimensional image. The intermediate image forming optical member 20 is a member capable of forming an intermediate image (curved image) having a shape that is at least partially curved using light projected from the display device 10, and details thereof will be described later. The concave mirror 30 receives light emitted from the intermediate image formed by the intermediate image forming optical member 20 and reflects it toward the display surface (wind shield WS).

  On the display surface of the display device 10, information useful for driving the vehicle (for example, character information such as a numerical value of the vehicle speed or km / h) is displayed as necessary. Light including a two-dimensional display image displayed on the display surface of the display device 10 is emitted from the display device 10, passes through the intermediate image forming optical member 20, is reflected by the concave mirror 30, and is emitted from the opening OP. The The light emitted from the opening OP is reflected by the surface of the windshield WS and travels toward the eye point EP. Therefore, the driver can visually recognize the display image projected by the HUD device 100 at the position of the eye point EP. Actually, the driver visually recognizes the virtual image IMG displayed at a predetermined position farther than the windshield WS. Since the concave mirror 30 has optical magnification, it can be projected in an enlarged state of the display image visually recognized by the driver.

  In the example of FIG. 1, the light emitted from the HUD device 100 is reflected by the surface of the windshield WS, but an optical reflecting member called a combiner or a half mirror may be used instead of the windshield WS.

<Description of optical path>
2 and 3 are for explaining the relationship between the shape of the display image (planar shape or curved shape) introduced into the concave mirror 30 and the shape of the virtual image (curved shape or planar shape) visually recognized by the driver. FIG. 2 and 3, the point f represents the focal point of the concave mirror 30, and the point c represents the spherical center of the concave mirror 30. 2 and 3, it is assumed that the concave mirror 30 has a single radius of curvature in order to facilitate understanding of the principle of the present invention.

  FIG. 2 shows an optical path when the intermediate image forming optical member 20 does not exist in the vehicle projection display apparatus shown in FIG. In the case of FIG. 2, since the display surface of the display device 10 has a planar shape, the display image 10A before being introduced into the concave mirror 30 also has a planar shape.

  In this case, when the display image 10A is reflected by the concave mirror 30, it is affected by the shape of the reflecting surface (curved surface shape), so that the image formed on the windshield WS is curved. As a result, the virtual image IMG visually recognized by the driver has a curved shape (that is, field curvature occurs). For example, the virtual image IMG has a distortion in the depth direction of the optical axis.

  On the other hand, FIG. 3 shows an optical path when the intermediate image forming optical member 20 “exists” (that is, in the present embodiment) in the vehicle projection display apparatus shown in FIG. In the case of FIG. 3, as will be described later, the intermediate image forming optical member 20 forms a curved intermediate image (curved image) 20 </ b> A, and the intermediate image 20 </ b> A is introduced into the concave mirror 30. As will be described later, the intermediate image 20A is formed to have a shape that can reduce the curvature of field caused by the shape of the concave mirror 30 and the windshield WS.

  Therefore, in this case, unlike the case of FIG. 2 described above, the image formed on the windshield WS is not curved. As a result, the virtual image IMG visually recognized by the driver has a planar shape (that is, no curvature of field occurs). Thereby, even when the concave mirror 30 is used in the optical system of the HUD device 100 and the windshield WS is used as the display surface, the influence thereof is reduced and the visibility of the display image can be improved.

  2 and 3, for the sake of convenience, only the influence of the concave mirror 30 is shown. However, since the surface of the windshield WS is also generally a curved surface, the curved surface of the windshield WS is also an image surface. It can be a factor causing curvature.

  Therefore, the shape of the intermediate image (curved image) formed by the intermediate image forming optical member 20 may be determined in consideration of both the influence of the concave mirror 30 and the influence of the windshield WS, for example. As a result, a virtual image IMG having no curvature of field is obtained as shown in FIG. However, the shape of the intermediate image does not necessarily have to be determined in consideration of both of them. If the shape of the intermediate image is determined in consideration of at least one of the concave mirror 30 and the windshield WS, the intermediate image forming optical member 20 is used. The curvature of field can be reduced as compared with the case where no exists.

<Configuration of Projection Display Device for Vehicle of Embodiment>
The configuration and optical path of the HUD device 100 are shown in detail in FIG. In FIG. 4, for convenience of explanation, the optical characteristics of the intermediate image forming optical member 20 are schematically expressed by one convex lens (20 in the figure), and the optical characteristics of the concave mirror 30 and the windshield WS are expressed by one convex lens ( This is schematically represented by 30) in the figure. This convex lens (30 in the figure) is also referred to as an optical system 30 because of its function. FIG. 4 does not mean that the actual intermediate image forming optical member 20 is configured by the single convex lens illustrated, and does not mean that the actual optical system is configured by the single convex lens.

  Further, in FIG. 4, a projector 11 is used as a specific display device 10. The projector 11 includes a light source 11a, a display 11b, and a projection lens 11c. The display 11b is a transmissive liquid crystal display. However, various types of display devices can be used as the display 11b as in the case of a general projector. For example, reflective devices such as LCOS (Liquid Crystal on Silicon) and DMD (Digital Micro-mirror Device) may be used, and the projector is configured by a scanner using MEMS (Micro Electro Mechanical Systems). May be. As the light source, an LED, a laser, or the like can be used.

  In the example of FIG. 4, when the illumination light emitted from the light source 11a passes through the display 11b, the light or the like is modulated according to the two-dimensional display image displayed on the display 11b, and includes information on the display image. Is incident on the projection lens 11c.

  The light projected from the projection lens 11 c of the projector 11 is introduced into the intermediate image forming optical member 20. The intermediate image forming optical member 20 includes an optical lens, a convex lens, a Fresnel lens, a microlens array, a reflecting mirror, and the like, and is at least partially curved using light projected from the projection lens 11c (see FIG. 3). The intermediate image 20A having the curved shape described above is formed. The intermediate image 20A is formed so as to have a shape that can reduce the curvature of field caused by the optical system 30 by adjusting the shape and optical characteristics of the various lenses described above. Then, light emitted from the intermediate image 20 </ b> A is introduced into the optical system 30.

  The optical system 30 forms light emitted from the intermediate image 20A, and the formed light is visually recognized as a virtual image IMG at the eye point EP.

  As described above, in the HUD device 100, since the intermediate image 20A has the curved shape described above, image distortion due to each element included in the optical system 30 is reduced. As a result, the virtual image IMG has a planar shape (see also FIG. 3). That is, field curvature is reduced.

  Further, the HUD device 100 can transmit light efficiently because the intermediate image forming optical member 20 directly guides the light of the intermediate image 20A to the optical system 30 side without using the screen of the conventional device. Thereby, for example, the light emission intensity required for the light source 11a of the projector 11 shown in FIG. 4 can be lowered, and power consumption and heat generation can be reduced. Furthermore, since the scattering of external light such as sunlight can be prevented, the visibility of the virtual image IMG is improved.

Here, the features of the above-described embodiment of the vehicle projection display apparatus according to the present invention are briefly summarized in the following (1) to (3).
(1)
A projection unit (display device 10 or projector 11) that projects light to be formed as a display image on a display surface formed by a windshield (WS) of a vehicle or a light reflecting member in the vicinity of the windshield; An optical system (concave mirror 30) that guides the light projected from the projection unit to the display surface, and makes it possible to visually recognize a virtual image of the display image from a predetermined eye point (EP) (HUD) Device 100),
The light projected from the projection unit (10 or 20) is used to form an intermediate image (20A) having at least a partially curved shape, and light emitted from the intermediate image is emitted from the optical system (30). An intermediate image forming optical member (20) to be introduced into
Projection display device for vehicle (100).
(2)
In the vehicle projection display device described in (1) above,
The intermediate image forming optical member (20)
The intermediate image having a shape for correcting an aberration related to field curvature generated in the virtual images (60A to 60C) due to at least one characteristic of the optical system (50 or 40) and the display surface (WS) is formed. ,
Projection display device for a vehicle.
(3)
The vehicle projection display device according to (1) above,
The intermediate image forming optical member (20)
Including at least one of an optical lens, a Fresnel lens, and a microlens array,
Projection display device for a vehicle.

DESCRIPTION OF SYMBOLS 100 HUD apparatus 10 Display device 10A Display image 11 Projector 20 Intermediate image formation optical member 20A Intermediate image 30 Concave mirror (optical system)
IMG Virtual Image OP Opening WS Windshield EP Eyepoint

Claims (2)

A projection unit that projects light to be formed as a display image on a display surface formed by a windshield of a vehicle or a light reflecting member in the vicinity of the windshield, and the light projected from the projection unit is displayed. An optical system that leads to a surface, and a vehicular projection display device that makes it possible to visually recognize a virtual image of the display image from a predetermined eye point,
An intermediate image forming optical member that forms an intermediate image having a shape that is at least partially curved using the light projected from the projection unit, and that introduces light emitted from the intermediate image into the optical system;
The optical system includes a concave mirror,
The intermediate image forming optical member is disposed between the projection unit and the concave mirror so that the intermediate image is positioned between the focal point of the concave mirror and the concave surface of the concave mirror ,
The intermediate imaging optical member includes a microlens array;
Projection display device for a vehicle. The vehicle projection display device according to claim 1,
The intermediate image forming optical member is
Forming the intermediate image having a shape for correcting an aberration related to field curvature generated in the virtual image due to the characteristics of at least one of the optical system and the display surface;
Projection display device for a vehicle.

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