JP2010256867A - Head-up display and image display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a head-up display which excels in visibility to a virtual image even under a condition that external light is bright, and also to provide an image display method. <P>SOLUTION: The head-up display is equipped with: an image display 17 which generates a primary image from light emitted from an illuminating light source 12 based on an image signal from the outside, and emits the primary image as primary image light; a relay lens 18 which magnifies the primary image light; a reflection mirror 20 which generates a secondary image by imaging of the incident primary image light, and reflects the secondary image as secondary image light; and a concave mirror 21 which generates the virtual image of the secondary image, based on the incident secondary image light, and reflects the virtual image as virtual image light, to magnify and project the virtual image light. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a head-up display and an image display method with good visibility.

  Conventionally, in vehicles such as automobiles, various display devices for displaying driving information in front of the driver's seat are attached, but in addition to this, recently, for example, speed information etc. A head-up display capable of displaying driving information, navigation information, road congestion information transmitted via radio, and the like as virtual images has been proposed.

  This type of head-up display has various structural forms. As an example of a conventional example, there is a head-up display that can adjust the display size of a virtual image according to the driver's preference (see, for example, Patent Document 1). ).

  FIG. 14 is a block diagram showing a conventional head-up display.

  The conventional head-up display 100 shown in FIG. 14 is disclosed in Patent Document 1, and will be described briefly with reference to Patent Document 1.

  As shown in FIG. 14, the conventional head-up display 100 includes a movable liquid crystal panel 102, a reflecting mirror 103, and a concave mirror 104 in a casing 101.

  At this time, when the driver operates the switch 105 in the direction of reducing (A) or expanding (B), the liquid crystal panel 102 can be moved back and forth with respect to the reflecting mirror 103 by a command from the controller 106. .

  Further, the image displayed on the liquid crystal panel 102 by the image signal from the image processing circuit 107 is reflected by the reflecting mirror 103, changes the direction of the optical path, enters the concave mirror 104, and then the image reflected by the concave mirror 104. Is further changed in the direction of the optical path and is incident on the rear surface of the field-of-view area of the front wind seal (not shown), so that the driver can visually recognize the display information as a virtual image 108 in front of the front wind seal, and the liquid crystal panel 102 It is described that the display size of the virtual image 108 can be adjusted according to the driver's preference by moving it back and forth.

JP 2003-175744 A

  By the way, according to the conventional head-up display 100, the display size of the virtual image 108 displayed in front of the front window seal can be adjusted according to the moving position of the liquid crystal panel 102. And a drive source for driving the movement mechanism are required, and there is a problem that the head-up display 100 becomes expensive.

  Further, in the conventional head-up display 100, since the display position of the virtual image 108 on the front wind seal is fixed by the arrangement relationship of the reflecting mirror 103 and the concave mirror 104, the height position of the driver's eyes E varies. There is a problem that it is difficult to deal with.

  Further, in the conventional head-up display 100, in order to secure a sufficient distance and viewing angle from the front wind seal to the height position of the driver's eye E, the curvature radius of the concave mirror 104 is increased and the magnification is decreased. It is necessary to suppress.

  On the other hand, in order to improve the visibility of the virtual image 108 seen through the front window seal and display the virtual image 108 in a large size, it is necessary to reduce the radius of curvature of the concave mirror 104 and increase the magnification. If the radius of curvature of the concave mirror 104 becomes small, the distortion of the image increases abruptly by moving the viewpoint a little, and the problem that the virtual image 108 becomes difficult to see because the field of view is narrow arises. Can not be satisfied at the same time.

  Therefore, in the conventional head-up display 100, when the display size of the virtual image 108 is increased, it can be solved by moving the liquid crystal panel 102 in the direction of enlarging (B). However, as described above, the cost increases. Yes. Further, since the virtual image 108 becomes dark when enlarged and displayed, a problem arises in the visibility of the virtual image 108 when the weather is fine.

  Therefore, without moving an image display element (for example, a liquid crystal panel) that displays an image, a virtual image can be displayed on a projection surface formed on a windshield of an automobile, for example, and the eyes of an observer (driver) can be displayed. An object of the present invention is to provide a head-up display and an image display method capable of visually recognizing a virtual image 108 even with respect to variations in height position and having good visibility with respect to a virtual image even under bright light conditions.

This invention is made | formed in view of the said subject, 1st invention is a light source (12),
When the light (Lw) emitted from the light source (12) enters the pixel region (17a), a primary image (G1) is generated based on the image signal (22a) from the outside, and the generated 1 An image display element (17) that emits as primary image light (Lg1) including the next image (G1);
A zoom optical system (18) for enlarging the primary image light (Lg1) emitted from the image display element (17);
The primary image light (Lg1) enlarged by the variable magnification optical system (18) is disposed at the imaging position, and the incident primary image light (Lg1) forms an image to form a secondary image (G2). ) And reflecting the secondary image light (Lg2) including the secondary image (G2) as a reflection mirror (20);
A virtual image of the secondary image (G2) is generated on the optical path of the secondary image light (Lg2) reflected by the reflection mirror (20) and based on the incident secondary image light (Lg2). A concave mirror (21) for reflecting and enlarging and projecting as virtual image light (Lvi) including the virtual image;
A head-up display (10A or 10B).

The second invention is the above-described head-up display (10A or 10B) of the first invention.
When the primary image light (Lg1) incident on the reflection mirror (20) is reflected as the secondary image light (Lg2), the secondary image light (Lg2) is diffused with a predetermined directivity. A head-up display (10A or 10B).

The third invention is the head-up display (10A or 10B) of the first or second invention described above,
The reflection mirror (20) includes a reflection layer (20b) formed on the substrate (20a) on the incident surface side of the primary image light (Lg1) and a diffusion layer laminated on the reflection layer (20b). A head-up display (10A or 10B) comprising a layer (20c).

The fourth invention is the head-up display (10A or 10B) of the second or third invention described above,
When the position where the reflection intensity of the light reflected from the reflection mirror (20) has a maximum value is 0 degree, and the angle at which the reflection intensity is half of the maximum value (e) is a half-value angle (α), The head-up display (10A or 10B) is characterized in that the absolute value of the half-value angle (α) is 5 ° or more and 10 ° or less.

The fifth invention is the head-up display (10C) of any one of the first to fourth inventions described above,
A head-up display characterized in that a field lens (30) is disposed in close contact or close to the front of the reflection mirror (20) between the variable magnification optical system (18) and the reflection mirror (20). is there.

The sixth invention is the head-up display (10D) of any one of the first to fourth inventions described above,
A field lens (30) is installed in close contact with or close to the front of the reflection mirror (20) between the variable magnification optical system (18) and the reflection mirror (20), and the field lens (30) is mounted. A head-up display configured to be movable in a direction orthogonal to the central axis (J) of the field lens (30).

Further, the seventh invention generates a primary image (G1) based on an image signal (22a) from the outside when light enters the pixel region (17a), and generates the primary image ( A primary image light emitting step of emitting as primary image light (Lg1) including G1);
A primary image light enlarging step for enlarging the primary image light (Lg1) emitted in the primary image light emitting step;
The primary image light (Lg1) magnified in the primary image light magnification step forms an image to generate a secondary image (G2), and a secondary image light including the generated secondary image (G2) ( Lg2) is a diffuse reflection step that diffusely reflects with directivity,
The secondary image light (Lg2) reflected in the diffuse reflection step is further reflected by the concave reflection surface (21a), and virtual image light (Lvi) including a virtual image of the secondary image is projected onto the projection surface (1a). A virtual image projection step,
It is the image display method characterized by having.

  According to the present invention, even if a small image display element is used, a large virtual image can be displayed to an observer, and the observer can visually recognize the projected virtual image without distortion.

  Further, even if the viewpoint is shifted, the observer can see the virtual image well, and the virtual image can be seen well even under a condition where the outside light is bright.

  In addition, when another observer with a different physique observes the projected virtual image, the projected virtual image can be viewed well.

It is the figure typically shown in order to demonstrate the head-up display and image display method of the Example which concerns on this invention. It is the figure which expanded and showed the reflective mirror for secondary image image formation shown in FIG. (A), (b) is the figure typically shown in order to demonstrate the reflective directivity of the diffused layer formed in the reflective mirror for secondary image image formation shown in FIG. In the head-up display according to the embodiment of the present invention, when the reflecting mirror for forming the secondary image has a reflection directivity, the virtual image can be seen through the windshield even if the observer moves his eyes. It is a light ray diagram which showed a mode typically. It is a figure for demonstrating the specific design example when the head-up display of the Example which concerns on this invention is applied, for example to a motor vehicle. In the head-up display of the Example which concerns on this invention, it is a figure for demonstrating the result when simulating the relationship between the brightness with respect to the half value angle of the diffused layer formed in the reflective mirror for secondary image formation, and a viewing radius. is there. It is the figure typically shown in order to demonstrate the head-up display and image display method of the modification 1 which deform | transformed the Example partially. It is the figure typically shown in order to demonstrate the head-up display and image display method of the modification 2 which changed the Example partially. It is the figure typically shown in order to demonstrate the comparative example with respect to the head-up display and image display method of the modification 2 which changed the Example partially. (A), (b) is a head-up display of Modification 2 in which the embodiment is partially modified, and when a field lens is installed in close contact or close to the front of the reflecting mirror for secondary image formation, It is the light ray figure which showed typically a mode that a virtual image can be seen through a windshield even if an observer moves eyes. (A), (b) is a head-up display of a modification 3 in which the embodiment and the modification 2 are partially deformed, and a reflecting mirror and a field lens for forming a secondary image are orthogonal to the central axis of the field lens. FIG. 6 is a ray diagram schematically showing how a virtual image can be seen through the windshield even if the observer moves his eyes when configured to be movable. (A), (b) is a head-up display of a third modification obtained by partially modifying the embodiment and the second modification, and the observer looks at the state shown in FIG. 10 together with the state shown in FIG. It is the light ray figure which showed typically a mode that a virtual image can be seen through a windshield even if it moves. (A), (b) is sectional drawing which expanded and showed the field lens and reflection mirror which are used for the modification 2 and the modification 3. FIG. It is the block diagram which showed the conventional head-up display.

  Hereinafter, an embodiment of a head-up display and an image display method according to the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1, a head-up display 10A according to an embodiment of the present invention includes an illumination light source 12, a collimator lens 13, a field lens 14, and a polarizing plate in a box-shaped housing 11A. 15, a polarizing beam splitter 16, an image display element 17, a relay lens 18 serving as a variable power optical system, an optical path changing mirror 19 that changes the optical path direction, and a secondary image formed and 2 formed. A reflecting mirror 20 for reflecting the next image and a concave mirror 21 are provided. Further, an image signal generator 22 for sending an image signal to the reflective liquid crystal panel 17 is provided. The image signal generator 22 may be disposed in the housing 11A.

  Here, as the image display element 17, a reflective liquid crystal panel, a transmissive liquid crystal panel, or a DMD (Digital Micromirror Device) can be applied. In the following description, a high-definition image is used as the image display element 17. An example in which a reflective liquid crystal panel that can be easily displayed is applied will be described.

  At this time, the image signal generator 22 is based on speed information provided in the automobile, driving information from various instruments, navigation information from the navigation device, road congestion information transmitted wirelessly, and the like. An image signal 22a is generated. When the reflective liquid crystal panel (image display element) 17 is driven based on the image signal 22a, the incident light is modulated by the reflective liquid crystal panel 17, and the primary image is displayed on the pixel region 17a of the reflective liquid crystal panel 17. (Primary image) G1 is displayed.

  Here, the head-up display 10A of the embodiment will be specifically described. The illumination light source 12 can be a metal halide lamp, a xenon lamp, a halogen lamp, an LED (light emitting diode), or the like, and is disposed on the lower right side of the housing 11A. The non-polarized white light Lw emitted from the illumination 12 is converted into parallel light by the collimator lens 13 and then enters the polarizing plate 15 through the field lens 14. The incident non-polarized white light Lw is separated and transmitted by the polarizing plate 15 by separating only linearly polarized light, for example, S-polarized light (or P-polarized light), which is a polarized light component in one direction.

  The S-polarized light (or P-polarized light) transmitted through the polarizing plate 15 enters the polarizing beam splitter 16 and is reflected by the polarization separation film 16a formed therein. The reflected S-polarized light (or P-polarized light) is changed by 90 ° in the direction of the optical path to the direction of the reflective liquid crystal panel 17, and is transmitted through the field lens 14 to illuminate the pixel region 17 a of the reflective liquid crystal panel 17. ing.

  A configuration in which the polarizing plate 15 is not provided is also possible. In this case, linear polarization in one direction may be separated from unpolarized white light by the polarization separation 16a of the polarization beam splitter 16.

  Thereafter, in the reflective liquid crystal panel 17, the polarization state of the incident light is modulated based on the image signal 22a sent from the image signal generator 22. Specifically, S-polarized light (or P-polarized light), which is a polarization component of incident light, is converted into P-polarized light (or S-polarized light) that is a polarization component in a different direction based on the image signal 22a, and the primary image. G1 is formed. The primary image light Lg1 including the formed primary image G1 is reflected by the reflective liquid crystal panel 17 and emitted.

  Then, the primary image light Lg1 emitted from the reflective liquid crystal panel 17 is incident on the polarization beam splitter 16 again. In the polarization beam splitter 16, for example, P-polarized light (or S-polarized light) as a component modulated by the reflective liquid crystal panel 17 in the primary image light Lg1 is transmitted through the polarization separation 16a and emitted. The emitted P-polarized light (or S-polarized light) enters the relay lens 18 and is enlarged by the relay lens 18. The enlarged primary image light Lg 1 ′ enters the mirror 19 and the optical path direction is secondary. It is changed in the direction of the image forming reflection mirror 20 to be reflected and emitted. The P-polarized light (or S-polarized light) which is emitted from the optical path changing mirror 19 and incident on the reflecting mirror 20 and enlarged primary image light Lg1 ′ is formed on the reflecting mirror 20 to form a secondary image ( Secondary image) G2 is generated and reflected by the reflection mirror 20.

  At this time, the optical path changing mirror 19 does not have a function of forming the secondary image G2, but has a function of changing the optical path by the arrangement relationship between the relay lens 18 and the reflecting mirror 20 for forming the secondary image. It is only what it has.

  Here, the reflection mirror 20 for forming the secondary image described above is an optical member constituting the main part of this embodiment, and the relay lens 18 is used by using a normal mirror (not shown) that simply reflects light. Although there is a configuration in which the secondary image G2 is formed by the light emitted from the light, the reflection mirror 20 for forming the secondary image in this embodiment has a reflection directivity having a reflection directivity on the surface on which light enters and exits. A surface 20bc is formed.

  That is, in the reflection mirror 20 for forming a secondary image, as shown in an enlarged view in FIG. 2, a mirror-like reflection layer 20b is formed of, for example, a metal film on the optical glass substrate 20a, and further on the reflection layer 20b. A diffusion layer 20c that diffuses the light incident on the surface with reflection directivity is laminated.

  At this time, the diffusion layer 20c is light transmissive and allows incident light to be incident on the lower reflection layer 20b and reflected by the reflection layer 20b. It is formed using polymers, pearl materials, and fine particles.

  Therefore, the reflection mirror 20 for forming a secondary image has a reflection directivity on the optical glass substrate 20a as described above by laminating the reflection layer 20b and the diffusion layer 20c on the optical glass substrate 20a. The following description assumes that the reflection directivity surface 20bc is formed.

  Note that the reflective layer 20b formed on the optical glass substrate 20a is not necessarily a metal film, but may have a high reflectance with respect to incident light, and the diffusion layer 20c is not laminated on the reflective layer 20b. It can also be used as a normal mirror.

  In addition, the diffusion layer 20c is not limited to the above-described materials, and, for example, a diffusion control film (DCF) manufactured by Luminit may be adhered to the reflective layer 20b with a transparent adhesive. Since this diffusion control film has a high transmittance and a plurality of types of diffusion angles are prepared in advance, a film having a desired diffusion angle can be selected.

  At this time, as shown in FIGS. 3A and 3B, the reflection intensity e has a Gaussian distribution characteristic with respect to the diffusion angle θ of the diffusion layer 20c. The reflection directivity of the diffusion layer 20c can be evaluated using the half-value angle ± α.

  The half-value angle ± α is set to 0 degree when the light ray perpendicularly incident on the diffusion layer 20c is reflected, and the reflection intensity is reduced to half the value e / 2 with respect to the maximum reflection intensity e. This is the angle at which the light is incident and appears on the positive side and the negative side with the incident light beam as the center.

  In this embodiment, the absolute value is set to 5 ° to 10 ° as the half-value angle ± α of the diffusion layer 20c. The reason for this setting will be described in detail later.

  Here, referring again to FIG. 1, the secondary image light Lg2 including the secondary image G2 formed on the reflection mirror 20 for forming a secondary image will be described. The secondary image (secondary image) G2 formed on the reflection mirror 20 is converted into secondary image light Lg2, reflected by the reflection mirror 20, and light of the secondary image light Lg2 reflected by the reflection mirror 20. It injects toward the concave mirror 21 installed on the road.

  Further, the secondary image light Lg2 including the secondary image G2 incident on the concave mirror 21 generates a virtual image VI of the secondary image, is reflected by the concave reflecting surface 21a of the concave mirror 21, and includes the virtual image VI of the secondary image. The virtual image light Lvi is projected on the projection surface 1a formed on the observer (driver) side through the opening 11a opened above the housing 11A, for example, on the light-transmitting windshield 1 provided in the automobile. Is done.

  At this time, the region of the projection surface 1 a formed on the windshield 1 is also called a “combiner”. This combiner is formed of, for example, a light-transmitting metal film, a dielectric multilayer film, or a hologram film, and has a characteristic of transmitting a part and reflecting a part. Moreover, a combiner may be formed in the one part area | region of the windshield 1, or may be formed in the whole windshield.

  Thereafter, a part of the virtual image light Lvi including the virtual image VI of the secondary image projected on the projection surface 1a formed on the windshield 1 is reflected to the observer (driver) side on the projection surface 1a and observed by the observer. Therefore, the observer can observe the virtual image light Lvi of the secondary image, that is, the tertiary image through the windshield.

  Therefore, in the image display method according to the present invention, the step of emitting the primary image light Lg1 including the primary image G1 displayed in the pixel region 17a and the primary image light Lg1 including the primary image G1 are enlarged. Obtaining secondary image light Lg2 including the secondary image G2, imaging the secondary image light Lg2 including the secondary image G2 on the reflection directivity surface 20bc having reflection directivity, and reflecting the image; Reflecting the secondary image light Lg2 including the secondary image G2 reflected by the reflection directivity surface 20bc by the concave reflection surface 21a and projecting the virtual image light Lvi including the virtual image VI of the secondary image onto the projection surface 1a; ,have.

  At this time, when a simple mirror (not shown) for forming a secondary image is used as a comparative example of the embodiment, the secondary image light Lg2 including the secondary image G2 is a simple mirror (not shown). ), The reflected light travels straight, so that the virtual image VI can be observed when the eye E of the observer (driver) is at the design height position. , The virtual image VI tends to be difficult to observe.

  Therefore, in this embodiment, the secondary image light Lg2 including the secondary image G2 is reflected while being diffused by the reflection directivity surface 20bc formed on the reflection mirror 20 for forming the secondary image. By appropriately setting the half-value angle ± α (FIG. 3), the virtual image VI is improved so that it can be sufficiently visually recognized corresponding to the movement of the height position of the eye E of the observer.

  If the reflection directivity surface 20bc is too diffused like a completely diffusing surface, the amount of light that actually reaches the observer's eye E out of the reflected rays becomes very small. Most of the brightness is discarded, and the observed virtual image VI becomes a very dark image.

  That is, FIG. 4 shows a virtual image even if the observer moves the eye E when the reflection mirror 20 for forming a secondary image has a reflection directivity in the head-up display 10A of the embodiment according to the present invention. The state in which VI can be seen through the windshield is schematically represented by a light ray diagram.

  In FIG. 4, the height position A of the observer's eye E is the original design position for observing the virtual image VI-a, but even when the height of the observer's eye E is moved to the position B or C, Since the reflected light of the secondary image light Lg2 is diffused with directivity, the observer can visually recognize the virtual images VI-b and VI-c at the respective positions.

  At this time, the absolute value of the half-value angle ± α of the diffusion layer 20c formed on the reflection mirror 20 for forming the secondary image is set to 5 ° or more and 10 ° or less for the reason described later. When the absolute value of the half-value angle ± α is set to 10 °, for example, the height position of the eye E of the observer is displayed in the vertical direction (from the position A to the position B or C direction) indicated by the field radius in the figure. Even if it is moved about 100 mm, it is possible to prevent the brightness from almost decreasing. Here, the visual field radius is the height position of the eye E when the height position of the observer's eye E is moved from the design position A to the up (position B) direction and down (position C) direction. It is half the value of the movement range.

  Note that the field radius described above can be adjusted by changing the curvature of the concave mirror 21, and if the curvature is small, in other words, if the curvature radius is large, the field radius value can be set large, but the head-up display 10A is large. It will become. Therefore, a specific design example will be described below.

  Next, a specific design example when the head-up display 10A of the embodiment is applied to, for example, an automobile will be described with reference to FIG.

  As shown in FIG. 5, in the head-up display 10A of the embodiment, the reflective liquid crystal panel 17 has a rectangular pixel area 17a having an outer size of 18 mm diagonal, and the primary image G1 displayed in the pixel area 17a. Is enlarged by the relay lens 18 to form a secondary image G2 having a double diagonal of 36 mm on the reflection directivity surface 20bc of the reflection mirror 20.

  Further, the radius of curvature of the concave reflecting surface 21a of the concave mirror 21 is 500 mm.

  Here, the length from the height position of the eye E of the observer to the center position of the projection plane 1a of the windshield 1 is a, and the length from the center position of the projection plane 1a of the windshield 1 to the position of the virtual image VI is b, the length from the center position of the concave reflecting surface 21 a of the concave mirror 21 to the center position of the projection surface 1 a of the windshield 1 c, and the reflection directivity surface 20 bc of the reflecting mirror 20 for secondary image formation from the concave mirror 21. The length to the center position of the concave reflecting surface 21a is defined as d.

  When the dimensions a, c and d are set to a = 450 mm, c = 300 mm, and d = 200 mm, the dimension of b is b = 1550 mm.

  That is, the virtual image VI is formed at a position 1550 mm away from the projection surface 1a of the windshield 1. That is, this means that a virtual image V1 having a length of 112 mm and a width of 140 mm is formed 2 meters ahead of the height position of the eyes E of the observer, and a sufficient distance of 450 mm is secured from the windshield 1 to the observer. be able to.

  Further, the size of the virtual image V1 is projected after being magnified about 10 times with respect to the primary image G1 displayed in the pixel region 17a of the reflective liquid crystal panel 17.

  Here, when the head-up display 10A of the embodiment is designed as described above, the half value of the diffusion layer 20c formed on the reflection mirror 20 for secondary image formation previously shown in FIGS. 1 and 2 is used. The result when simulating the relationship between the brightness with respect to the corner and the field radius will be described with reference to FIG.

In FIG. 6, the horizontal axis indicates the absolute value α [°] of the half-value angle ± α of the diffusion layer 20c, the left side of the vertical axis indicates the brightness [cd / m ² : candela / square meter], and the right side of the vertical axis. Indicates a viewing radius [mm].

  At this time, a 50-watt lamp is used as the light source 12 (FIG. 1). As shown in FIG. 6, by expanding the diffusibility of the diffusion layer 20 c formed on the reflection mirror 20 for forming the secondary image, the field of view, that is, the radius in the range where the virtual image VI (FIG. 1) can be visually recognized, is expanded. It can be seen that the viewing radius (marked with ■) is saturated when the half-value angle α is 10 °.

On the other hand, the brightness (marked with a circle) is attenuated by the square of the half-value angle α, so that it can be seen that the brightness rapidly decreases when the directivity is increased. Even when daytime bright virtual image VI (FIG. 1) in order to be visually recognized is 5000 cd / ^{m 2} or more, desirably required luminance of 10000 cd / ^{m 2.}

  In consideration of moving the head during driving, it is desirable to secure a radius of field of view of 50 mm or more, preferably 100 mm or more. Taking these into consideration, the absolute value of the half-value angle ± α is preferably 5 ° or more and 10 ° or less, thereby achieving both brightness and a wide field of view.

  Accordingly, the visual range of the virtual image VI can be expanded by setting the absolute value of the half-value angle ± α of the diffusion layer 20c formed on the reflecting mirror 20 for forming the secondary image to 5 ° or more and 10 ° or less. Therefore, it is possible to deal with variations in the height position of the observer's eyes E, and of course, it is possible to cope with differences in the height of the observer.

  At this time, the brightness can also be adjusted by increasing the power of the light source 12 (FIG. 1). However, considering the use in the vehicle and environmental measures, it is important to save power and reduce power consumption. is required. Therefore, in the embodiment, the reflection directivity surface 20bc having the reflection directivity is formed on the reflection mirror 20 for forming the secondary image to ensure the brightness, so that the virtual image VI can be obtained even under a bright external light condition. The head-up display 10A with good visibility can be provided.

  As described above, according to the head-up display 10A and the image display method of the embodiment, the primary image light Lg1 including the primary image G1 displayed in the pixel region 17a of the reflective liquid crystal panel 17 is enlarged by the relay lens 18. Then, after forming a secondary image G2 on the reflecting mirror 20 for forming a secondary image and reflecting it as secondary image light Lg2 including the secondary image G2, the secondary image light Lg2 including the secondary image G2 is reflected. Is reflected by the concave reflecting surface 21a of the concave mirror 21, and the virtual image light Lvi including the virtual image VI of the secondary image is projected onto the projection surface 1a of the windshield 1.

  As a result, by forming a secondary image G2 obtained by enlarging the primary image G1, a large virtual image VI can be finally displayed to an observer even when a small reflective liquid crystal panel (image display element) 17 is used. In addition, the magnification by the concave mirror 21 can be kept low. Therefore, since a sufficient distance can be provided between the observer and the projection surface 1a of the windshield 1, the observer can visually recognize the projected virtual image VI satisfactorily without distortion.

  At this time, the reflection directivity surface 20bc of the reflection mirror 20 for image formation of the secondary image has reflection directivity, and has a directivity while diffusing the secondary image light Lg2 including the secondary image G2. Therefore, the virtual image VI projected through the concave mirror 21 can be viewed well even if the observer slightly shifts the viewpoint. Furthermore, since the virtual image VI can be efficiently delivered to the observer's eyes, it is possible to provide the head-up display 10A having good visibility with respect to the virtual image VI even under bright external light conditions.

  Next, a head-up display and an image display method according to the first modification obtained by partially modifying the embodiment will be described only with respect to differences from the embodiment with reference to FIG.

  In FIG. 7, the same components as those in the embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

  As shown in FIG. 7, in the head-up display 10B and the image display method according to the first modification in which the embodiment is partially modified, a reflection type liquid crystal panel is provided at the lower right in FIG. (Image display element) 17 is disposed, and primary image light Lg1 including the primary image G1 displayed in the pixel region 17a of the reflective liquid crystal panel 17 is expanded by the relay lens 18. The enlarged primary image light Lg1 ′ is incident on the reflection mirror 20 for image formation of the secondary image disposed on the upper right side in the housing 11B so as to face the relay lens 18, and is secondary on the reflection mirror 20. An image G2 is formed.

  Therefore, since it is not necessary to provide the optical path changing mirror 19 described in the embodiment, the point that the head-up display 10B of the modification 1 can be simplified and downsized is different from the embodiment.

  Accordingly, in the first modification, as in the embodiment, when the virtual image VI is displayed through the windshield using the head-up display 10B of the first modification, the virtual image VI is displayed on the pixel region 17a of the reflective liquid crystal panel 17. The primary image light Lg1 including the primary image G1 is enlarged by the relay lens 18 to form the secondary image G2 on the reflection mirror 20, and the secondary image light Lg2 including the secondary image G2 reflected by the reflection mirror 20 is formed. Is reflected on the concave reflecting surface 21a of the concave mirror 21 and the virtual image light Lvi including the virtual image VI of the secondary image is projected onto the projection surface 1a of the windshield 1, so that the same effect as in the embodiment can be obtained. .

  Next, a head-up display and an image display method according to Modification 2 in which the embodiment is partially modified will be described only with respect to differences from the embodiment with reference to FIGS.

  8 to 10, the same components as those of the embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, in the head-up display 10 </ b> C and the image display method according to the second modification obtained by partially modifying the embodiment, a variable power optical system is provided in front of the reflective liquid crystal panel (image display element) 17. A field lens 30 is disposed between the relay lens 18 and the reflection mirror 20 that laminates the reflection layer 20b and the diffusion layer 20c on the optical glass substrate 20a and reflects the formed secondary image. The point which is installed in close contact with or close to the reflection directivity surface 20bc of the reflection mirror 20 is different from the embodiment.

  On the other hand, as a comparative example of Modification 2, when a field lens is not installed in front of the reflection mirror 20 in which the reflection layer 20b and the diffusion layer 20c are laminated on the optical glass substrate 20a as shown in FIG. The embodiment corresponds to a first modification in which the embodiment and the embodiment are partially modified.

  That is, as shown in FIG. 9, the primary image light Lg1 including the primary image G1 displayed in the pixel region 17a of the reflective liquid crystal panel 17 is magnified by the relay lens 18, and this magnified primary image light Lg1. 'Is formed as a secondary image G2 on the reflection directivity surface 20bc of the reflection mirror 20 for secondary image formation. The secondary image light Lg2 including the secondary image G2 is reflected as diffused light by the reflection directivity surface 20bc of the reflection mirror 20, and then the secondary image light Lg2 which is diffused light is incident on the concave reflective surface 21a of the concave mirror 21. . At this time, if there is no field lens in front of the reflection mirror 20, the reflection angle of the secondary image light Lg2 reflected by the reflection directivity surface 20bc of the reflection mirror 20 is wide. Since some of the light does not reach the concave mirror 21 and the reflected light from the concave mirror 21 becomes dark, uneven brightness may occur.

  Therefore, as described above with reference to FIG. 8, the field lens 30 is installed in close contact with or in front of the reflection mirror 20. With this configuration, the primary image light Lg1 ′ is incident on one side of the center axis J of the field lens 30 and then passes through the field lens 30, so that the secondary image light Lg2 becomes diffused light. As a result, the reflection angle is narrowed and all of the luminous flux of the secondary image light Lg2 reaches the reflection directivity surface 20bc of the reflection mirror 20 for forming the secondary image, brightens the reflected light from the concave mirror 21, and causes uneven brightness. Can be prevented. Thereafter, the virtual image light Lvi including the virtual image VI (FIG. 1) of the secondary image is reflected toward the windshield 1 by the concave reflecting surface 21a of the concave mirror 21.

  Specifically, as shown in FIGS. 10A and 10B, in the head-up display 10 </ b> C and the image display method of the second modification, the field lens 30 is installed in close contact with or close to the front of the reflection mirror 20. When this is done, the primary image light Lg1 emitted from the reflective liquid crystal panel 17 is magnified by the relay lens 18. The enlarged primary image light Lg1 ′ is incident on an intermediate portion on one side of the central axis J of the field lens 30 and between the central axis J and the lens outer peripheral portion, passes through the field lens 30, and Reflected by the reflecting mirror 20 for forming a secondary image. The reflected secondary image light Lg2 is emitted from the field lens 30. At this time, the direction of the reflected light that is emitted from an intermediate portion between the central axis J of the field lens 30 and the lens outer peripheral portion and travels toward the concave mirror 21. Since the curve is small, it is all incident on the concave mirror 21.

  Thereafter, the virtual image light Lvi reflected by the concave reflecting surface 21a of the concave mirror 21 is reflected by the windshield 1 toward the observer. At this time, the height of the eye E of the observer is set to the position F, the position G, or Since the virtual image VI can be seen through the windshield even if it is moved to the position H, when the observer observes the projected virtual image VI with a greatly changed posture, or a virtual image projected by another observer with a different physique Even when observing the VI, the projected virtual image VI can be viewed well.

  Next, a head-up display and an image display method according to the third modification obtained by partially modifying the embodiment and the second modification will be described with reference to FIGS. 11 and 12 only with respect to differences from the first embodiment and the second modification. To do.

  In FIG. 11 and FIG. 12, the same components as those in the embodiment and the modified example 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 11 and 12, in the head-up display 10D and the image display method of the modification 3 in which the embodiment and the modification 2 are partially modified, they are installed in front of the reflective liquid crystal panel (image display element) 17. The field lens 30 is disposed in close contact with the front of the reflection mirror 20 between the relay lens 18 serving as the variable magnification optical system and the reflection mirror 20 that reflects the formed secondary image and the formed secondary image. In addition, the reflecting mirror 20 and the field lens 30 are fixed to the rack 31, and the reflecting mirror 20 and the field lens 30 are orthogonal to the central axis J of the field lens 30 by the rotation of the gear 32 meshed with the rack 31. The point which is comprised so that a movement to a direction is different from an Example and the modification 2 is.

  In the third modification, the case where the field lens 30 is installed in close contact with the front of the reflection mirror 20 will be described below. However, the field lens 30 may be installed close to the front of the reflection mirror 20, in this case. In this case, the field lens 30 may be attached to the rack 31 so that at least the field lens 30 can be moved perpendicularly to the central axis J of the field lens 30.

  That is, as shown in FIGS. 11A and 11B, the gear 32 meshed with the rack 31 is driven to rotate, and the reflecting mirror 20 and the field lens 30 are orthogonal to the central axis J of the field lens 30 in the direction of the arrow. The primary image light Lg1 ′ is incident on the lens outer peripheral portion on one side of the field lens 30 from the central axis J and away from the central axis J. This incident position is a lens outer peripheral part with respect to the incident position on the field lens 30 shown in FIG. The primary image light Lg1 incident on the field lens 30 is reflected by the reflection mirror 20 for forming a secondary image and is emitted from the field lens 30 as the secondary image light Lg2. At this time, the direction of the reflected light emitted from the field lens 30 and directed toward the concave mirror 21 is bent more than in the case of FIGS. 10A and 10B described above.

  Thereafter, the virtual image light Lvi reflected by the concave reflecting surface 21a of the concave mirror 21 is reflected by the windshield 1 toward the observer. At this time, the height of the observer's eye E is set to the position M or the position N or Even if it is moved to the position O, the virtual image VI can be seen through the windshield. Here, the position M, the position N, or the position O is an upper position in the arrow direction with respect to the position F, the position G, or the position H shown in FIG.

Further, as shown in FIGS. 12A and 12B, when the field lens 30 is moved to the position indicated by the solid line in FIG. 12B, the position becomes the same as that in FIG. Even when the height position of the eye E is moved to F, position G, or position H, the projected virtual image VI can be viewed well. Further, when the field lens 30 is moved to the position indicated by the solid line in FIG. 12B, the position is the same as that in FIG. 11B. The projected virtual image VI can be seen well even when moved to the position O. From the above-described Modification 2 and Modification 3, the field lens 30 installed in close contact with or close to the front of the reflection mirror 20 The function of making the brightness uniform and the function of satisfactorily viewing the projected virtual image VI even when the height position of the observer's eye E is greatly changed.

  At this time, as shown in FIG. 13A, the field lens 30 is formed in a circle around the central axis J, and the convex curved surface 30a serves as an image light entrance / exit surface, while the convex curved surface 30a The opposite flat surface 30 b is a surface that is in close contact with or close to the reflection directivity surface 20 bc of the reflection mirror 20.

Further, as described above, the field lens 30 does not necessarily have a circular shape because the incident / exit of the image light is on one side of the central axis J, and instead of the field lens 30 shown in FIG. Thus, a semicircular field lens 30 ′ as shown in FIG. 13B may be used, and the reflection mirror 20 ′ may be formed in accordance with the shape of the field lens 30 ′.

  In the embodiment and the modifications 1 to 3 described in detail above, the case where the reflective liquid crystal panel 17 is used as the image display element has been described. However, when the transmissive liquid crystal panel (not shown) is used as the image display element, The primary image displayed in the pixel area of the transmissive liquid crystal panel may be enlarged by a relay lens to obtain a secondary image. When a DMD (not shown) is used as the image display element, a large number of mirrors are used. The primary image displayed by the above can be enlarged by a relay lens to obtain a secondary image.

  The head-up display and the image display method according to the present invention can be used in automobiles, airplanes, trains, construction vehicles, and other game machines.

1 ... windshield, 1a ... projection surface (combiner),
10A: Head-up display of the embodiment,
10B: Head-up display of Modification 1
10C: Head-up display of Modification 2
10D: Head-up display of Modification 3
11A, 11B ... casing, 11a ... opening,
12 ... Light source for illumination, 13 ... Collimator lens, 14 ... Field lens,
15 ... Polarizing plate, 16 ... Polarizing beam splitter,
17 ... Image display element (reflection type liquid crystal panel), 17a ... Pixel region,
18 ... Variable magnification optical system (relay lens), 19 ... Mirror for optical path change,
20 ... a reflection mirror for forming a secondary image, 20a ... an optical glass substrate, 20b ... a reflection layer,
20c ... diffusion layer, 20bc ... reflection directivity surface,
21 ... concave mirror, 21a ... concave reflecting surface, 22 ... image signal generator, 22a ... image signal,
30, 30 '... field lens, 30a ... convex curved surface, 30b ... flat surface,
31 ... rack, 32 ... gear,
E ... Eye, G1 ... Primary image (primary image), G2 ... Secondary image (secondary image), VI ... Virtual image of secondary image,
Lw ... white light, Lg1 ... primary image light, Lg1 '... primary image light magnified by a variable magnification optical system,
Lg2 ... secondary image light, Lvi ... virtual image light,
e: Maximum reflection intensity when a light beam perpendicularly incident on the diffusion layer of the reflecting mirror for secondary image formation is reflected, θ: Diffusion angle, ± α: Half-value angle,
J: central axis of the field lens 30 or 30 ′.

Claims (7)

A light source;
An image display element that generates a primary image based on an external image signal when the light emitted from the light source enters the pixel region, and emits the primary image light including the generated primary image; ,
A variable magnification optical system for enlarging the primary image light emitted from the image display element;
A secondary image is generated by forming an image of the incident primary image light, which is disposed at an imaging position of the primary image light magnified by the zoom optical system, and includes the secondary image. A reflection mirror that reflects as the next image light,
A virtual image of the secondary image is generated based on the incident secondary image light, arranged on the optical path of the secondary image light reflected by the reflection mirror, and reflected and magnified as virtual image light including the virtual image A concave mirror to project,
A head-up display comprising:   2. The head according to claim 1, wherein the secondary image light diffuses with a predetermined directivity when the primary image light incident on the reflection mirror is reflected as the secondary image light. Up display.   The said reflection mirror is provided with the reflective layer formed on the board | substrate on the incident surface side of the said primary image light, and the diffused layer laminated | stacked on the said reflective layer, The Claim 1 or Claim characterized by the above-mentioned. 2. The head-up display according to 2.   The absolute value of the half-value angle is 5 ° when the position where the reflection intensity of the light reflected from the reflection mirror is the maximum value is 0 degree and the angle at which the reflection intensity is half the maximum value is the half-value angle. The head-up display according to claim 2 or 3, wherein the angle is 10 ° or less.   5. The head-up according to claim 1, wherein a field lens is disposed in close contact with or close to the front of the reflection mirror between the variable magnification optical system and the reflection mirror. display.   A field lens is installed in close contact with or close to the front of the reflecting mirror between the variable magnification optical system and the reflecting mirror, and the field lens can be moved in a direction perpendicular to the center axis of the field lens. The head-up display according to any one of claims 1 to 4, wherein the head-up display is provided. A primary image light emission step of generating a primary image based on an image signal from the outside when light is incident on the pixel region, and emitting the primary image light including the generated primary image;
A primary image light expanding step for expanding the primary image light emitted in the primary image light emitting step;
The primary image light magnified in the primary image light enlarging step forms an image to generate a secondary image, and diffusely reflects with directivity as the secondary image light including the generated secondary image. A diffuse reflection step;
A virtual image projecting step of projecting virtual image light including a virtual image of the secondary image onto a projection surface by further reflecting the secondary image light reflected in the diffuse reflection step on a concave reflecting surface;
An image display method characterized by comprising:

Images