JP2021131497A - Head-up display device - Google Patents

Abstract

To provide a head-up display device capable of simultaneously displaying virtual images with different virtual image distances without lowering luminance.SOLUTION: Disclosed is a head-up display device which includes a screen disk 40 rotating at a high speed, in which an intermediate screen 4 to which an intermediate image is projected from an image display device is provided on a transparent substrate 5. The intermediate screen 4 is divided into a first region 41 on the inner peripheral side consisting of the plane whose normal axis is the axis of rotation and a second region 42 on the outer peripheral side having the spiral surface. The intermediate image projected into the first region 41 forms a virtual image in a close range, and the intermediate image projected into the second region 42 forms the virtual image of near to far distance.SELECTED DRAWING: Figure 3A

Description

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

A head-up display (HUD) device is known that projects an image onto the rear surface of a screen (combiner) made of a half mirror and displays it as a virtual image at a predetermined distance in front of the screen. Head-up display devices installed in automobiles display information such as speed and mileage, which was conventionally displayed on the instrument panel (instrument panel), also in front of the front window (windshield), and in recent years, A virtual image is displayed over a wide area using the windshield as a screen. Such a head-up display device reduces the movement of the driver's line of sight and supports safer driving. For example, as shown in FIG. 2, in cooperation with the mounted camera, a red figure (Ivn) or the like is superimposed and marked on a pedestrian or an oncoming vehicle in front, or in cooperation with a car navigation system, a course is taken. Augmented Reality (AR) head-up display devices have been developed that display arrows (Ivm, Ivf) and the like indicating the above on the road and the distance to the destination.

In general, a head-up display device displays an image on a screen from an image projector equipped with a light source such as an LED (Light Emitting Diode) or LD (Laser Diode) via an optical element such as a reflector or a lens. Project at the angle of incidence. The head-up display device is, for example, a DLP (registered trademark) method in which an image is formed on a diffusion screen by a DMD (Digital Micromirror Device) to form an intermediate image, or a diffusion screen by a MEMS (Micro Electro Mechanical Systems) mirror. A laser scanning method is known in which a laser beam is scanned vertically and horizontally to draw an intermediate image. Further, the position of the virtual image in the depth direction (distance from the observer's eyes (virtual image distance: VID)) is determined by the optical path length from the image projector or the diffusion screen (intermediate screen) to the screen.

In an AR head-up display device for automobiles, it is preferable that the arrow indicating the course as described above is displayed at a long virtual image distance according to the road surface or the like in the driver's line of sight, while the alert is in front. That is, it is preferable that the image is displayed with a short virtual image distance. Therefore, an intermediate screen is provided on a disk that rotates at high speed along the axis along the optical path direction, and the height of the intermediate screen is set with a step along the diameter of the disk so that the position of the intermediate screen in the axial direction changes on the circumference. A device in which an intermediate screen is formed on a plurality of surfaces having a difference (position in the axial direction) or a spiral surface inclined along the circumference of a disk is disclosed (Patent Document 1). By repeatedly changing the height of the area where one frame (one frame) of the intermediate image is projected on the intermediate screen at high speed within a predetermined range, it is possible to display a plurality of virtual images having different virtual image distances at the same time. can.

International Publication No. 2019/070080

In a head-up display device as described in Patent Document 1, since virtual images of n virtual image distances are alternately displayed within one frame (n ≧ 2), the number of stages of virtual image distances (n). As the number increases, the time for displaying each virtual image per frame becomes shorter, and the brightness of the virtual image decreases to 1 / n and becomes darker. Further, since the intermediate image cannot be projected during the period when the boundary (step) between the regions having different heights of the intermediate screen passes through the projection region from the image projector, the brightness of the virtual image increases as n increases. Further decrease. As a result, it becomes difficult to visually recognize the virtual image in a particularly bright surrounding environment such as a snowy road in backlight or in fine weather. Therefore, according to Patent Document 1, the decrease in brightness is suppressed by forming the intermediate screen as a helicoid whose height changes continuously. Here, in order to project a plurality of intermediate images in one frame, a DLP method having a high response speed is preferable, and in the DLP method, R (red) and G (green) are used for full-color display. , B (blue) three-color light sources are switched within one frame and irradiated to obtain an apparently full-color image (time division method). When the range of the displayed virtual image distance is large, the gradient of the helicoid surface of the intermediate screen becomes large, so that the height difference when the images of each color constituting one full-color intermediate image are projected becomes large, and the virtual image is colored. There will be a gap. Further, in the laser scanning method, the height difference of the intermediate screen becomes large depending on the timing when the laser beam is irradiated in the frame, and the virtual image may be distorted.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a head-up display device capable of ensuring the brightness of a virtual image and simultaneously displaying virtual images having different virtual image distances.

The above problem of the present invention is solved by the following configuration.

(1) The intermediate image is screened with a rotation-driven substrate, an intermediate screen provided on the substrate, and an image projection means for projecting light for forming an intermediate image on the intermediate screen. A head-up display device that projects onto one surface and simultaneously displays a plurality of virtual images having different virtual image distances on the other surface side of the screen.
The intermediate screen is divided into two or more regions with a circle centered on the axis of rotation of the substrate as a boundary, and the adjacent regions having a step at the boundary have different positions in the axial direction. At least one of the regions is a head-up display device, wherein the position in the axial direction differs depending on the position in the circumferential direction of the circle in the region.

(2) The head-up display device according to (1), wherein at least one of the regions of the intermediate screen is formed of a plane whose position in the axial direction is constant.

(3) The innermost region of the intermediate screen is composed of the plane, and the portion of the intermediate image formed in the innermost region forms a virtual image having the shortest virtual image distance (3). The head-up display device according to 2).

(4) The intermediate screen according to any one of (1) to (3), wherein each of the regions comprises one or both of a helicoid surface and a plane having the axis as a normal. Head-up display device.

(5) In the intermediate screen, at least one of the regions has a step along the radial direction of the circle, and the position in the axial direction is different in the region, and the step in the entire region is the step of the circle. The head-up display device according to (4), which is arranged along one diameter.

(6) The intermediate screen according to any one of (1) to (5), wherein the difference in position in the axial direction in the entire region is equal to or less than the depth of focus of the light projected from the image projection means. Head-up display device.

(7) The head-up display device according to any one of (1) to (6), wherein the intermediate screen is a transmissive diffuser, and the substrate transmits light.

According to the head-up display device according to the present invention, it is possible to simultaneously display virtual images having different virtual image distances and secure the brightness of the virtual images having a part of the virtual image distances.

It is a schematic block diagram of the head-up display device which concerns on this invention. This is an example of a virtual image displayed by the head-up display device according to the embodiment of the present invention in the field of view of the observer. It is an external view of the screen disk provided with the intermediate screen of the head-up display device which concerns on embodiment of this invention. FIG. 3A is a cross-sectional view of FIG. 3A. It is a schematic diagram explaining the structure of the intermediate screen of the head-up display device which concerns on embodiment of this invention, and is the top view of FIG. 3A. It is a figure which shows the transition in the circumferential direction of the position in the rotation axis direction of the intermediate screen and the virtual image distance, and the time chart of the head-up display device which concerns on embodiment of this invention. It is a top view of the intermediate screen of the head-up display device which concerns on embodiment of this invention, and is the schematic diagram explaining another aspect about the projection area of an intermediate image. It is sectional drawing of the screen disk provided with the intermediate screen of the head-up display device which concerns on the modification of embodiment of this invention. It is a top view of the intermediate screen of the head-up display device which concerns on the modification of embodiment of this invention. It is a top view of the intermediate screen of the head-up display device which concerns on the modification of embodiment of this invention. It is a figure which shows the transition in the circumferential direction of the position in the rotation axis direction of the intermediate screen and the virtual image distance, and the time chart of the head-up display device which concerns on the modification of embodiment of this invention. It is a top view of the intermediate screen of the head-up display device which concerns on the modification of embodiment of this invention. It is a figure which shows the transition in the circumferential direction of the position in the rotation axis direction of the intermediate screen and the virtual image distance, and the time chart of the head-up display device which concerns on the modification of embodiment of this invention.

Hereinafter, the head-up display device according to the embodiment (embodiment) for carrying out the present invention will be described with reference to the drawings. The members shown in the drawings may be exaggerated in size, positional relationship, etc., and may have a simplified shape or structure in order to clarify the explanation. Further, in the following description, members of the same or the same quality are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

[Head-up display device]
FIG. 1 is a schematic view of a head-up display device according to the present invention, and is a configuration diagram seen from the side of a state mounted on an automobile. The head-up display device 10 is an AR head-up display device for automobiles whose screen S is the front window of the automobile, and is in front of the front window S with respect to the driver (observer) O (only the eyes are shown in the figure). The virtual image Iv is displayed on. Therefore, the head-up display device 10 is housed in the instrument panel of the automobile, and as indicated by an arrow, an image is projected from the window formed on the top plate T of the instrument panel onto the inner surface of the front window S. do. The front window S functions as a half mirror that transmits and reflects light, and the reflecting surface (the surface inside the vehicle) is generally concave.

The head-up display device 10 is an image display device that projects light for forming an intermediate image on a screen disk 40 composed of a transparent substrate 5 and a transmissive intermediate screen 4 provided on one surface thereof, and an intermediate screen 4. (Image projection means) 2 is provided, and further, an image forming module 1 for forming an image displayed by the image display device 2 based on an external signal, and projection optics arranged on an optical path from the image display device 2 to the intermediate screen 4. System 3, cover 62 accommodating screen disk 40, motor 7 for rotationally driving screen disk 40 and cover 62, shaft 61 connecting screen disk 40 and cover 62 with motor 7, and intermediate image formed on intermediate screen 4. It is provided with a magnifying reflector 8 that reflects the above and projects it onto the inner surface of the vehicle of the front window S, and a casing (not shown) that accommodates these and forms an integral unit. The head-up display device 10 simultaneously displays n virtual images (n ≧ 2) having different virtual image distances, and in the present embodiment, four virtual images of Ivc, Ivn, Ivm, and Ivf are displayed in ascending order of the virtual image distances. Display (n = 4).

A virtual image displayed by the head-up display device according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 is an example of a real view through the front window S and a virtual image displayed by the head-up display device in the field of view of the driver O. The head-up display device 10 can display virtual images Ivc, Ivn, Ivm, and Ivf (appropriately collectively, virtual image Iv) in the virtual image field of view E. The shape of the virtual image field E is not particularly specified, but it is preferably wider in the H (horizontal) direction with respect to the V (vertical) direction, and is represented by an elongated rectangle in the H direction in FIG. The virtual image field of view E is divided into a display area E1 of about 1/4 on the lower side and a display area E2 other than that by an elliptical arc, and _{a virtual image of n 1} virtual image distance is displayed in the display area E1. Displays virtual images with n ₂ virtual image distances (1 ≦ n ₁ <n, 2 ≦ n ₂ ≦ n, n ₁ + n ₂ ≧ n). Each of n ₁ and n ₂ is preferably 6 or less, more preferably 4 or less, and the smaller the value, the higher the brightness of the virtual image Iv. In the present embodiment, a virtual image Ivc at a close distance is displayed in the display area E1, and other virtual images Ivn, Ivm, and Ivf are displayed in the display area E2 (n ₁ = 1, n ₂ = 3). The allocation of the display areas E1 and E2 in the virtual image field E can be designed by the shape of the intermediate screen 4 and the arrangement in the head-up display device 10, as will be described later.

The virtual image Ivc at a close distance is apparently displayed on the front window S, and the virtual image distance is, for example, 4 m. The virtual image Ivc is information that is generally displayed on the instrument panel, information that is always displayed during driving, and the like. For example, the traveling speed, the fuel level warning light (empty mark), and the destination when using the car navigation system. Distance to. Further, in the present embodiment, since the virtual image Ivc is displayed with high brightness, it is preferable to use it for an alert or the like. Further, in the present embodiment, since the virtual images Ivn, Ivm, and Ivf are not displayed in the display area E1, the display area E1 is designed so that the display of the virtual images Ivn, Ivm, and Ivf is unnecessary and does not interfere with the operation. Will be done. The virtual images Ivn, Ivm, and Ivf are displayed so as to be superimposed on the actual scene according to the situation in cooperation with a car navigation system or the like, and the virtual image distances are, for example, 7 m, 15 m, and 24 m, respectively. The short-distance virtual image Ivn is, for example, a figure or a symbol that is superimposed and displayed on a pedestrian, an oncoming vehicle, or the like approaching the vicinity of the front side of the vehicle body. The medium-distance virtual image Ivn is, for example, an arrow indicating a lane change to a right turn lane, which is superimposed on the road surface in front of the vehicle. The long-distance virtual image Ivf is, for example, an arrow displayed on an intersection scheduled to turn right ahead. Hereinafter, each element of the head-up display device 10 will be described in detail.

(Image formation module)
The image forming module 1 includes a printed circuit board and an integrated circuit (IC) mounted on the printed circuit board, generates image data based on a signal input from the outside, and outputs the image data to the image display device 2. The image forming module 1 may be provided integrally with the image display device 2, or may be connected to the image display device 2 by a flexible flat cable (FFC) or the like.

(Image display device)
The image display device 2 is composed of a light source, a spatial light modulator, and the like, and projects light for forming a two-dimensional intermediate image on a projection area e (see FIG. 4) of the intermediate screen 4. As described in the virtual image display method described later, the image display device 2 has a high response speed because it switches and projects each intermediate image forming two or more virtual images having different virtual image distances to be displayed at the same time within one frame. Is preferable. The frame rate is preferably 30 fps or more, and more preferably 60 fps or more. Further, in the case of full-color display by the time division method, the display period of each intermediate image is further divided into three and displayed by switching for each color, but the divided unit period δ is long and one region in the virtual image field E. If the difference between the virtual image distances of the virtual images displayed in (display area E2) is large, the virtual images are likely to undergo color shift. Therefore, although it depends on the difference between the virtual image distances and the length of the non-display period, the response speed of the image display device 2 is 10 times the frame rate, and further, in one region (E1, E2) in the virtual image field E. _{It is preferably (n 2} × 10) times or more the frame rate, which is multiplied by the maximum value of _{n 1} and n ₂ of the number of steps of the virtual image distance of the virtual image to be displayed, that _{is, n 2.} In the present embodiment, since n ₂ = 3, when the frame rate is driven at 60 fps, the response time of the image display device 2 is preferably 0.56 ms or less. As the image display device 2 having a high response speed, the DLP (registered trademark) method is suitable, and a DMD (Digital Micromirror) in which an LED light source or a laser light source and a micromirror driven by a MEMS (Micro Electro Mechanical Systems) are arranged in two dimensions is suitable. Device).

(Intermediate screen)
The intermediate screen 4 forms an image of the light emitted from the image display device 2 as an intermediate image through the projection optical system 3. Therefore, in the head-up display device 10, the intermediate screen 4 is preferably arranged within the depth of focus of the projection optical system 3. In the present embodiment, the intermediate screen 4 is a transmissive diffuser plate, for example, a microlens array, which diffuses the light incident from one surface side to a desired orientation angle and emits it to the other surface side. Such an intermediate screen 4 is formed of a transparent material such as glass or resin. Further, in the head-up display device 10, as shown in FIGS. 3A and 3B, the intermediate screen 4 is provided on one surface of the substrate 5 that transmits light to form the screen disk 40. The substrate 5 is made of a transparent material like the intermediate screen 4, and allows light to travel straight through. The intermediate screen 4 and the substrate 5 may be integrally formed as a screen disk 40, and the intermediate screen 4 can be formed by integrally molding or processing one surface of the substrate 5 into irregularities. Alternatively, the screen disk 40 may be configured by attaching a sheet-shaped intermediate screen 4 to the substrate 5. The screen disk 40 is fixed to a shaft 61 arranged parallel to the incident direction of light from the image display device 2 through a shaft hole 5h penetrating the substrate 5, and is unidirectional at the same rotation speed (r / s) as the frame rate. Continuously rotate to. In the present specification and drawings, the central axis (rotation axis) of the shaft 61 is the z-axis (cylindrical axis) of the cylindrical coordinate system, and a straight line orthogonal to the z-axis in an arbitrary radial direction of a circle centered on the z-axis. The direction) is referred to as the r direction (line of sight), and the circumferential direction is referred to as the θ direction. Unless otherwise specified, the upper side (+ z side) in FIG. 3B is the upper side, and the plan view means viewing from the + z side. Further, with respect to the screen disk and the intermediate screens constituting the screen disk, a plane having the z-axis as a normal is simply referred to as a plane. The incident side of the light is the + z (upper) side, that is, the light travels in the −z direction.

As shown in FIG. 4, the intermediate screen 4 has a ring shape centered on the shaft 61 in a plan view, and is further formed on the inner peripheral side by a circle centered on the shaft 61 (reference numeral 5b in the figure). It is divided into one region 41 and a second region 42 on the outer peripheral side, and as shown in FIGS. 3A and 3B, the second region 42 is arranged above the first region 41, that is, on the incident side of light. Therefore, the substrate 5 has a vertical (z-direction) step 5b in a plan view of the entire circle. Further, the first region 41 is composed of one plane whose normal is the z-axis. On the other hand, the second region 42 is mainly composed of an inclined surface (helicoid surface) 42s whose height (position in the z direction) continuously changes in the θ direction, and is continuous on the highest side of the inclined surface 42s. It has a plane 42h with the z-axis as the normal. Therefore, the substrate 5 has a vertical step 5g along the linear boundary in the r direction between the lower end of the inclined surface 42s and the plane 42h in the second region 42. Although the shape of the lower surface of the substrate 5 is not particularly specified, the thickness is not particularly specified so that the weight is not biased around the shaft 61 and the optical path length of the light transmitted from the intermediate screen 4 through the substrate 5 is made uniform. It is preferable to match the shape of the upper surface so that (length in the z direction) is uniform. In addition, in FIG. 3A, FIG. 3B, and FIG. 4, the screen disk 40 has a configuration in which the intermediate screen 4 is not provided at the edge portion and the central portion of the upper surface, but the intermediate screen 4 may be provided on the entire upper surface. Further, since the central portion and the like do not have to transmit light, the substrate 5 may be processed into a frosted glass shape or the like, or another material may be combined. Details of the surface shape of the intermediate screen 4 will be described later.

As shown in FIG. 4, the intermediate screen 4 includes the projection region e of the intermediate image in a plan view, and the projection region e is arranged over both the first region 41 and the second region 42. It is composed of. The shape and dimensions of the projection area e are set according to the arrangement and optical characteristics of the projection optical system 3, the intermediate screen 4, and the magnifying reflector 8 so that the virtual image Iv is displayed over the entire eye box. , It is set to a rectangle having an aspect ratio almost equal to that of the virtual image field E. Further, in the present embodiment, the screen disk 40 is arranged with respect to the image display device 2 so that the straight line in the r direction bisects the projection region e in the longitudinal direction. For convenience, the figure is such that the intermediate image moves with respect to the screen disk 40, but in the actual head-up display device 10, the position of the projection area e of the intermediate image projected from the image display device 2 in the plan view is fixed. As the screen disk 40 continuously rotates in the −θ direction, the projection region e orbits in the + θ direction on the intermediate screen 4. In the orbital movement, the position of the boundary 5b of the areas 41 and 42 is fixed with respect to the projection area e. The portion of the projection region e on the first region 41 (referred to as the projection region e1) is in the display region E1 of the virtual image field E, and the portion on the second region 42 (referred to as the projection region e2) is in the display region E2. Corresponds to each. Therefore, the intermediate screen 4 is configured so that an intermediate image forming a virtual image Ivc at a close distance is formed in the first region 41. Then, the intermediate images formed in the three regions 42n, 42m, and 42f shifted in the θ direction in the second region 42 are configured to form virtual images Ivn, Ivm, and Ivf with three stages of virtual image distances. Further, in the orbital movement, it is preferable that the period in which the projection region e2 straddles the step 5g is short, that is, the length of the projection region e2 in the θ direction, specifically, the length of the second region 42 in the inner diameter (diameter of the boundary 5b) direction. _{It is preferable that θ Pro} (hereinafter, the length of the projection region e in the θ direction) is sufficiently small with respect to one circumference (2π). When the θ-direction length θ _Pro of the projection region e is large, the brightness of the virtual images Iv, particularly the virtual images Ivn, Ivm, and Ivf displayed in the display region E2, decreases. Therefore, the intermediate screen 4 is designed to be sufficiently large with respect to the size of the projection area e.

The virtual image distance becomes longer as the optical path length from the intermediate image to the front window S becomes longer. Therefore, the more the intermediate screen 4 is arranged closer to the incident side of the light, that is, the higher the position (height) in the z direction is. , The virtual image distance becomes longer. The first region 41 is formed from a plane having the z-axis as a normal so that the height is constant regardless of the position in the θ direction in order to image only the intermediate image forming the virtual image Ivc at a close distance. Become. On the other hand, the second region 42 is configured so that the height differs depending on the position in the θ direction in order to make the second region 42 a variable region in which the position of the intermediate image on the optical path changes periodically due to the rotation of the screen disk 40. Here, FIG. 5 shows the target values VIDc, VIDn, VIDm, and VIDf of the virtual image distances of the virtual images Ivc, Ivn, Ivm, and Ivf. Also, the virtual image of the virtual image distance VID1 formed from the intermediate image formed in the first region 41 becomes the target value Vidc the (VID1 = Vidc) position of the intermediate image z _c (height of the first region 41) as a reference _{, The positions z n} , z _m , z _f of each intermediate image forming the virtual image of the virtual image distances VIDn, VIDm, and VIDf are shown.

The virtual image distance depends non-linearly on the optical path length from the intermediate image to the front window S, and the longer the virtual image distance, the greater the dependence on the optical path length. _{Therefore, as shown in FIG. 5, the positions z c} and z _{n of} the intermediate images forming the short-range virtual image Ivc and the short-range virtual image Ivn with a small difference in virtual image distance (VIDn-VIDc) are significantly different, while being medium. For virtual images of ~ long distance (VIDm, VIDf), the virtual image distance changes greatly with a small difference in _{the positions z m} and z _{f of the intermediate image.} The virtual image distance VID2 of the virtual image formed from the intermediate image formed in the second region 42 of the intermediate screen 4 causes a color shift in the virtual image when it changes suddenly. Therefore, as shown in FIG. 5, the virtual image distance from the virtual image distance VIDn It is preferable that the VIDf changes substantially linearly with respect to the θ direction. Therefore, the height of the second region 42 has a large gradient during the period of displaying the virtual image of the short to medium distance VIDn to VIDm, and the gradient is small during the period of displaying the virtual image of the medium to long distance VIDm to VIDf, and further. The gradient becomes 0 (a plane whose normal is the z-axis). That is, the second region 42 is composed of an inclined surface (helicoid surface) 42s in which the height continuously increases and the gradient gradually decreases in the + θ direction, and a plane 42h continuous on the highest side of the inclined surface 42s. In the second region 42, the region 42n for displaying the virtual image Ivn and the region 42m for displaying the virtual image Ivm, and the region 42m and the region 42f for displaying the virtual image Ivf are in the θ direction of the projection region e, respectively. Length θ _Pro Overlap. Further, since the height of the second region 42 changes abruptly at the boundary between the lower end of the inclined surface 42s and the plane 42h (step 5g in FIG. 3A), as will be described later in the virtual image display method. The period during which the projection region e of the intermediate image passes through the step 5 g is hidden to prevent color shift of the virtual image.

With such a configuration of the intermediate screen 4, the virtual images Ivn, Ivm, and Ivf are continuously displayed one by one in the display area E2 of the virtual image field E while the screen disk 40 makes one revolution, and these are apparently displayed. It is displayed at the same time, while the virtual image Ivc at a close distance is displayed in the display area E1. As described above, the intermediate screen 4 is preferably arranged within the depth of focus of the image display device 2. _{That is, it is preferable that the height difference (difference in the z direction) | z c −} z _f | between the plane 42h of the first region 41 and the second region 42 is equal to or less than the depth of focus of the image display device 2. Since the height difference of the intermediate screen 4 is designed according to the range of the virtual image distance of the virtual image Iv, the image display device 2 and the projection optical system 3 may be configured so that the depth of focus is equal to or greater than this height difference. preferable.

The cover 62 is a windshield that reduces noise such as vibration and wind noise due to high-speed rotation of the screen disk 40, and is provided as needed. The cover 62 is a housing for accommodating and sealing the screen disc 40. At least a portion overlapping the intermediate screen 4 in a plan view is formed of a transparent material, and the cover 62 is fixed to the shaft 61 together with the screen disc 40 and driven to rotate. Further, the cover 62 is the outer shape of a rotating body about the shaft 61, and is preferably not too large with respect to the screen disk 40, and can be, for example, a flat cylindrical shape.

The motor 7 continuously rotates the screen disk 40 in one direction with the rotation speed (r / s) as the frame rate. Further, if necessary, a power transmission component such as a gear is provided between the motor 7 and the shaft 61.

(Projection optics, magnifying reflector)
The projection optical system 3 is an optical element provided as necessary so that the light emitted by the image display device 2 is suitably projected onto the intermediate screen 4 so as to form an intermediate image. For example, the intermediate screen. This is a field lens that adjusts the light diameter, light intensity, spread, and the like of the light incident on the projection area e of 4. The projection optical system 3 is represented by one convex lens in FIG. 1, but is composed of two or more lenses, or a reflector (plane mirror, curved mirror) depending on the arrangement of the image display device 2 and the intermediate screen 4. May be further provided. The projection optical system 3 may further have a variable focus optical system. The magnifying reflector 8 magnifies the intermediate image formed on the intermediate screen 4 to a predetermined dimension and projects it on the inner surface of the vehicle of the front window S at a predetermined incident angle. The magnifying reflector 8 has a surface shape (for example, a surface shape inside the vehicle) based on the incident surface (inside surface of the vehicle) of the front window S so that the virtual image Iv can be displayed over the entire virtual image field of view E and at each predetermined virtual image distance. , Concave free-form surface), and the orientation and arrangement are further set. Further, if necessary, an optical element such as a reflector or a lens may be provided between the intermediate screen 4 and the magnifying reflector 8.

(Virtual image display method)
A virtual image display method using the head-up display device according to the embodiment of the present invention will be described with reference to FIG. Here, in FIG. 5, the horizontal axis is time.

The image display device 2 switches and projects the image pattern of the intermediate image for each unit period δ in which one frame is evenly divided into N, and also emits red (R), green (G), and blue (B) light sources. It is switched in order and pulsed one color at a time. In this specification, the operation for each unit period δ is referred to as a step. Therefore, the intermediate image is projected every time the projection region e moves the intermediate screen 4 in the + θ direction by 2π / N (= δ). However, the projection area e passes over the step 5g of intermediate screen 4 (δ × N _hid) period _{(N hid × δ <θ Pro} ≦ (N hid +1) × δ) is set to non-display period t0, The image display device 2 turns off the light source and does not project an image pattern. Therefore, the image display device 2 projects the pattern of the intermediate image as _{(N−N hid) per frame.} Here, as an example, assuming that N = 48 and N _hid = 9, an intermediate image is projected every time δ = π / 24 (= 7.5 °) moves, and 39 intermediate image patterns are projected per frame. be able to.

Therefore, the image display device 2 divides the steps 1 to 39 into n ₂ periods, that is, three periods, and in the projection region e2, 14 of the short-distance virtual image Ivn in the steps 1 to 13 (first display period t1). In steps ~ 26 (second display period t2), a pattern of a medium-distance virtual image Ivm is projected, and in steps 27 to 39 (third display period t3), a pattern of a long-distance virtual image Ivf is projected. A pattern of a virtual image Ivc at a close range is projected onto the projection area e1 through steps 1 to 39 (display periods t1 to t3). Further, since the color of the light source is switched for each step, the color for each step and the pattern for each area are as shown in Table 1. Even if the virtual image distance of the virtual image displayed for each step is different, the virtual images of the same color and the same pattern appear to be projected by repeatedly projecting the patterns of each color of R, G, and B twice or more within one period. To be averaged. As a result, the virtual image Ivn becomes the virtual image distance VIDn in the first display period t1, the virtual image Ivm becomes the virtual image distance VIDm in the second display period t2, and the virtual image Ivf becomes the virtual image distance VIDf in the third display period t3. In addition, these virtual images Ivn, Ivm, and Ivf are apparently displayed at the same time. Within one period, especially in the display period in which the height of the intermediate screen 4 changes during the period such as the second display period t2, the number of repetitions of R, G, and B is set to 2 times or more, preferably 3 times or more. .. As the number of repetitions increases with respect to the amount of change in the virtual image distance due to the height difference of the intermediate screen 4 within one period, the color shift of the virtual image Iv decreases, and the virtual image Iv becomes apparently free of color shift.

Since the intermediate image projected on the projection area e1 has a constant height, it may be projected throughout the period, that is, only the intermediate image forming the virtual image Ivc at a close distance is projected in the 40 to 48 steps. You may. As a result, the brightness of the virtual image Ivc can be displayed even higher regardless of the _{length θ Pro} in the θ direction of the projection region e. Further, the display periods t1, t2, and t3 do not have to be divided into equal times, and the longer the period, that is, the larger the number of steps, the higher the brightness of the virtual image at the virtual image distance can be relatively increased. Further, the display period can be divided into 4 or more, and a virtual image of 4 or more stages can be displayed in the range of the virtual image distances VIDn to VIDf. Further, when the number of steps in one period is sufficiently large, green with high luminosity factor can be displayed with high brightness by repeating R, G, G, B or R, G, B, G. Alternatively, the image display device 2 may be further provided with a yellow (Y) light source to provide full-color display in four colors of R, G, B, and Y.

In the head-up display device according to the present embodiment, the intermediate screen independently provides a region for projecting an intermediate image forming a virtual image of one of the virtual image distances in a plurality of stages. Can be displayed with high brightness. In particular, the region (first region) for projecting the intermediate image that forms the shortest virtual image of the three or more stages of virtual image distance is made independent, and the other two or more stages of virtual image distance is set in another region (second region). By alternately projecting the intermediate images forming the virtual image of the above in one frame, the height difference in the second region can be reduced, and the screen disk can be easily formed with high dimensional accuracy. In addition, for example, in the first region of the intermediate screen, only the intermediate image of the virtual image of the shortest distance is projected, and in the second region, the intermediate images of the virtual images of all the virtual image distances including the virtual image of the shortest distance are alternately projected. good.

In the intermediate screen, the fixed region of the intermediate image composed of one plane for displaying the virtual image of one virtual image distance can be provided on either the inner peripheral side or the outer peripheral side, but it is preferably provided on the inner peripheral side. By providing the variable region of the intermediate image having a height difference on the outer peripheral side having a long circumference, the gradient per circumference is suppressed, and it is easy to form with high dimensional accuracy. Further, since there is no step along the r direction in the inner peripheral region, the non-display period does not need to increase the size of the intermediate screen 4 with respect to the size of the projection region e, although it depends on the distribution of the projection regions e1 and e2. t0 (= δ × N _hid ) can be shortened. Further, the arrangement and distribution of the display areas E1 and E2 in the virtual image field of view E are arbitrary. For example, the display area E1 of the virtual image at a close distance can be arranged in the upper part of the virtual image field of view E. Alternatively, the display area E1 can be arranged at the lower right of the virtual image field E. In this case, the image display device 2 is arranged so that the projection area e is arranged with respect to the intermediate screen 4 as shown in FIG. And the screen disk 40 is placed. Further, for example, it is possible to display only a virtual image at a close distance in each of the upper part and the lower part in the virtual image field E, and in this case, the outer peripheral side of the second region is composed of a plane having the same height as the first region. Add areas, i.e. divide the intermediate screen 4 into three areas.

The image display device 2 can also apply a laser scanning method, and is composed of a laser light source and a MEMS-driven mirror. The laser scanning type image display device 2 simultaneously irradiates laser light of R, G, and B while controlling the output for each color, and scans the inside of the projection area e of the intermediate screen 4 with a mirror. For the display period in which the height of the intermediate screen changes during the period, it is preferable to repeatedly scan the projection area e twice or more and repeat it three times or more. Further, in general, in the laser scanning method, since the laser light moves in the V direction while reciprocating in the projection region e over the entire length in the H direction (longitudinal direction), the irradiation timing is in the V direction in the projection region e. It shifts. Therefore, the display areas E1 and E2 of the virtual image field E are preferably partitioned in the V direction as shown in FIG. A reflective liquid crystal panel made of LCOS (Liquid Crystal On Silicon) can be applied to the image display device 2, and an LED light source, a total of three liquid crystal panels for displaying image patterns of R, G, and B colors, and a dichroic prism. It is composed of a color synthesis optical system such as. The liquid crystal panel has _{a response speed of (n 2} / (1-θ _Pro / 2π)) or more of the frame rate, and the image pattern is switched for each display period to project an intermediate image on the intermediate screen 4.

[Modification example]
The present invention is not limited to the above-described embodiment, and can be modified without departing from the spirit of the present invention. For example, the following aspects can be mentioned.

The screen disk may be provided with an intermediate screen on a different side surface for each area. Specifically, as shown in FIG. 7, in the screen disk 40A, the portion of the second region 42 of the intermediate screen 4 is provided on the upper surface of the substrate 5A, and the portion of the first region 41 is provided on the lower surface of the substrate 5A. ing. The screen disk 40A has the same plan view as the screen disk 40 of the embodiment shown in FIG. When the height difference between the first region 41 and the second region 42 is large, the thickness of the substrate 5A can be suppressed and the weight of the screen disk 40A can be reduced by such a configuration.

The head-up display device may rotate the screen disk once in an integer cycle of 2 or more. For example, the screen disk 40B shown in FIG. 8 is rotated once in one cycle (π), that is, in two cycles. With such a configuration, the screen disk 40B has a shape having rotational symmetry on the shaft 61 (z axis), and the number of rotations is halved of the frame rate, so that vibration and noise due to rotation are reduced. In this case, if the non-display period t0 (= δ × N _hid ) is long around the period π, the brightness of the virtual image Iv decreases, so that the θ-direction length θ _Pro (see FIG. 4) of the projection region e is the period (π). ), The intermediate screen 4B is preferably designed to be sufficiently large with respect to the projection area e.

The head-up display device may include a linear motion mechanism connected to the screen disk 40 (40A, 40B) so that the entire head-up display device can reciprocate in the z direction and the virtual image distance of the virtual image Iv can be made variable. When the screen disk 40, that is, the entire intermediate screen 4 is moved, the virtual image distances of the medium to long distance virtual images Ivm and Ivf superposed on the actual scene change greatly even if the virtual image distance of the virtual image Ivc at a close distance hardly changes. Therefore, for example, the screen disk 40 can be moved according to the speed of the automobile. Alternatively, in addition to the screen disk 40, the projection optical system 3 or an optical system (not shown) arranged between the screen disk 40 and the magnifying reflector 8 may be moved.

The intermediate screen 4 of the above embodiment may have a step in the second region 42 other than the step 5 g between the regions 42f-42n. For example, with the region 42n as a plane, a step may be provided between the regions 42n-42m (not shown). In this case, since there are two non-display periods (δ × N _hid ) per period (2π), the intermediate screen 4 is designed to be sufficiently large with respect to the projection area e in order to suppress a decrease in the brightness of the virtual image Iv. It is preferable to be done. In this modification, the height of the region 42n does not change, and the height difference between the regions 42m-42f is small and the gradient can be reduced, so that the number of steps in each of the display periods t1, t2, and t3 is small. However, color shift is unlikely to occur in the virtual images Ivn, Ivm, and Ivf.

The intermediate screen may be configured such that two or more of the partitioned areas have varying heights. For example, as shown in FIG. 9, the intermediate screen 4C of the screen disk 40C of the head-up display device according to the modified example of the embodiment of the present invention has the first region 41, the third region 43, and the third region 43 in this order from the inner peripheral side. The substrate 5C is divided into three regions 42, and the substrate 5C has a step 5b1 between the regions 41-43 and a step 5b2 between the regions 43-42. The first region 41 on the innermost circumference and the second region 42 on the outermost circumference have the same configuration as the intermediate screen 4 of the embodiment shown in FIGS. 4 and 5. That is, the first region 41 is composed _{of a plane having a height z c} , and an intermediate image forming a virtual image Ivc at a close distance is projected. The second region 42 is composed of an inclined surface 42s and a plane 42h, and an intermediate image forming a virtual image Ivn, Ivm, Ivf of three stages of virtual image distance is projected. On the other hand, the third region 43 is configured to have two regions 43n, 43m on which an intermediate image forming a virtual image Ivn, Ivm of two stages of virtual image distance is projected. The portion of the projection region e on the first region 41 is referred to as the projection region e1, the portion on the second region 42 is referred to as the projection region e2, and the portion on the third region 43 is referred to as the projection region e3.

In this modification, the brightness of the virtual image Iv displayed in this region is increased to some extent by displaying the virtual images Ivn and Ivm of the two-step virtual image distance in a limited manner in the central region of the virtual image field E in the V direction. can do. Here, in order to increase the brightness of the virtual image Ivn at a short distance, as shown in FIG. 10, an intermediate image forming the virtual image Ivn is projected on the projection region e3 in the display periods t1 and t3. Specifically, in the display period t1, an intermediate image forming a virtual image Ivn is projected on the projection areas e2 and e3, and in the display period t2, an intermediate image forming a virtual image Ivm is projected on the projection areas e2 and e3. Then, an intermediate image forming a virtual image Ivf is projected on the projection area e2 and a virtual image Ivn is projected on the projection area e3. Therefore, the third region 43 has an inclination in which the height continuously increases in the + θ direction between the plane 43h _{1 having a height z n , the plane 43h 2} slightly higher than the height z _m , and the planes 43h ₁ , 43h _2. It consists of a surface 43s ₁ and an inclined surface 43s ₂ whose height is reduced. Since the heights of the inclined surface 43s ₁ of the third region 43 and the inclined surface 42s of the second region 42 are the same in a part of the regions, a step 5b2 is formed in this portion (indicated by a dotted line in FIG. 9). No. In this modification, since the range of the virtual image distance of the virtual image formed from the projected intermediate image is not wide in the third region 43, and if a step is provided between the regions 43n and 43m, the step 5g of the second region 42 Since the positions in the θ direction deviate from each other, it is preferable to have a configuration in which no step is provided. With such a configuration, even if the heights of the two regions 42 and 43 change to different heights, the non-display period t0 per cycle may be one time.

As another variant, the intermediate screen can also have all of the partitioned areas as variable areas of the intermediate image. For example, as shown in FIG. 11, the intermediate screen 4D of the screen disk 40D of the head-up display device according to the modified example of the embodiment of the present invention includes a first region 41A on the inner peripheral side and a second region 42 on the outer peripheral side. It is partitioned into. The second region 42 has the same configuration as the intermediate screen 4 of the embodiment shown in FIGS. 4 and 5. On the other hand, the first region 41A is configured to have two regions 41c, 41n on which an intermediate image forming a virtual image Ivc, Ivn of two stages of virtual image distance is projected. Therefore, the virtual images Ivc and Ivn are displayed in the display area E1 of the virtual image field of view E, and the virtual images Ivn, Ivm, and Ivf are displayed in the display area E2. That is, the short-distance virtual image Ivn can be displayed in the entire virtual image field of view E.

In this modification, in order to display the virtual image Ivc at a close distance displayed in the display area E1 with high brightness, an intermediate image forming the virtual image Ivc is projected in the display period t2 to t3 as shown in FIG. .. Specifically, in the display period t1, an intermediate image forming a virtual image Ivn is projected on the projection areas e1 and e2, that is, the entire projection area e. Then, in the display period t2, an intermediate image forming a virtual image Ivc in the projection area e1 and a virtual image Ivm in the projection area e2 is projected. Ivf is projected with the intermediate images that form each. Therefore, the first region 41A is the inclined surface 41s of the plane 41h ₂ and the plane 41h _1, and plane 41h _1, 41h + theta direction continuously height between _second height z _n of the height z _c is reduced A step 5g1 of the substrate 5D is provided at the boundary between the planes 41h _{2 to 41h 1.} The intermediate screen 4D aligns the positions of the portions of the regions 41A and 42 where the height changes abruptly in the θ direction so that the step 5g1 in the first region 41A and the step 5g2 in the second region 42 of the substrate 5D are aligned. They are aligned on one straight line in the r direction. With such a configuration, even if the heights of the two regions 41A and 42 change to different heights, the non-display period t0 per cycle may be one time. Further, since the height of the first region 41A on the inner peripheral side of the intermediate screen 4D also changes, the substrate 5D has a step 5s between the intermediate screen 4D and the central portion formed of a plane inside the first region 41A. Since the height of the central portion of the substrate 5D is the _{same as the plane 41h 2} of the first region 41A (height z _c ), the step 5s becomes a semicircle in a plan view.

In this modification, by displaying only the virtual images Ivc and Ivn of the two stages of virtual image distance in the display area E1 of the virtual image field E, the virtual image of the virtual image distance of all stages is displayed in one area. It can be displayed with brightness, and further, by allocating a long display period for one of the virtual images Ivc, it can be displayed with higher brightness.

As described above, the head-up display device according to the present invention can display a virtual image of a part of the virtual images of a plurality of virtual image distances displayed at the same time with high brightness by limiting the display area. can.

10 Head-up display device 1 Image formation module 2 Image display device (image projection means)
3 Projection optics 40, 40A, 40B, 40C, 40D Screen disk 4, 4B, 4C, 4D Intermediate screen 41, 41A 1st area 42 2nd area 43 3rd area 5,5A, 5B, 5C, 5D substrate 5b, 5b1,5b2 Step, Boundary 5g, 5g1,5g2 Step, Boundary 61 Shaft 62 Cover 7 Motor 8 Magnifying Reflector S Front Window (Screen)
Iv, Ivc, Ivn, Ivm, Ivf virtual image

Claims (7)

A substrate that is rotationally driven, an intermediate screen provided on the substrate, and an image projection means that projects light for forming an intermediate image on the intermediate screen are provided, and the intermediate image is placed on one surface of the screen. A head-up display device that projects and simultaneously displays a plurality of virtual images having different virtual image distances on the other surface side of the screen.
The intermediate screen is divided into two or more regions with a circle centered on the axis of rotation of the substrate as a boundary, and the adjacent regions having a step at the boundary have different positions in the axial direction. At least one of the regions is a head-up display device, wherein the position in the axial direction differs depending on the position in the circumferential direction of the circle in the region. The head-up display device according to claim 1, wherein at least one of the regions of the intermediate screen is formed of a plane whose position in the axial direction is constant. 2. The head-up display device described. The head-up according to any one of claims 1 to 3, wherein each of the regions comprises one or both of a helicoid surface and a plane having the axis as a normal. Display device. In the intermediate screen, at least one of the regions has a step along the radial direction of the circle, and the position in the axial direction is different in the region, and the step in the entire region is one of the circles. The head-up display device according to claim 4, which is arranged along a diameter. The head-up according to any one of claims 1 to 5, wherein the difference in the positions of the intermediate screen in the entire region in the axial direction is equal to or less than the depth of focus of the light projected from the image projection means. Display device. The head-up display device according to any one of claims 1 to 6, wherein the intermediate screen is a transmissive diffuser, and the substrate transmits light.

Images