Display device

Abstract

To provide a display device capable of displaying high-resolution video image information to a vehicle driver.SOLUTION: A display device provided herein is installed in a vehicle and includes a display panel. In the display device, a light flux travels from the display panel toward a display area of a windshield glass of a vehicle, where a travel direction of the light flux from the display panel is inclined away from a driver of the vehicle, and the display area of the windshield glass is near a bottom end of the windshield glass.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle information display device that projects video light onto a windshield, rear windshield, side glass, etc. (hereinafter collectively referred to as "vehicles") of an automobile, train, aircraft, etc., or a combiner, etc., and displays it. In particular, it relates to a vehicle information display device and a vehicle information display system that can reflect or transmit video information through a windshield, rear windshield, etc. and display it in one direction to the inside or outside of the vehicle.

Background Art

[0002] A so-called head-up display (HUD) device that projects video light onto the windshield or combiner of an automobile to form a virtual image and displays traffic information such as route information and traffic jam information, and automobile information such as fuel remaining amount and coolant temperature, is already known, for example, from Patent Document 1.

[0003] In this type of information display device, generally, in order to make the video information monitorable as a virtual image for the purpose of reducing the movement of the driver's viewpoint, the video displayed on the video display device is projected onto the driver's viewpoint using an optical system including a concave mirror (function of a convex lens) in many cases.

[0004] Also, although different from this type of information display device, generally, as a screen used in a video display device equipped with a screen, a transparent screen or a reflective screen provided with a light diffusion layer containing a binder and fine particles is already known from the following Patent Documents 2 and 3.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] In the above-described prior art head-up display type vehicle information display device, AR (Augmented-Reality) information, which is a virtual image, is displayed so as not to obstruct the driver's view of the outside of the vehicle. However, for example, when displaying information such as a map, the displayed map information may obstruct the outside view. In addition, in such a vehicle information display device, while it is desired to expand the displayable area, it is also required that the virtual image has high resolution and high visibility. Therefore, since high-quality images can be easily obtained and are inexpensive, liquid crystal display elements (liquid crystal display panels) are often used. On the other hand, for miniaturization of the set, small liquid crystal display elements are used, so that the resolution of the projected image obtained is insufficient, and a new problem has become clear that it is not suitable for displaying high-resolution images displayed on, for example, a smartphone.

[0007] In addition, such a head-up display type vehicle information display device is not intended to display video information to the outside of the vehicle. Therefore, when attempting to display video information to the outside of the vehicle, a video display device such as a display is mounted inside the vehicle, and the video information is displayed through the vehicle's glass. However, in that case, these video display devices will obstruct the driver's view, which is not preferable for safe driving.

[0008] Note that Patent Documents 2 and 3, which are prior art, disclose a reflective screen or a transparent screen provided with a light diffusion layer containing a binder and fine particles used in an information display device, but no teaching is given regarding the application to a vehicle related to the present invention, or specific methods, forms, or configurations therefor.

[0009] The present invention aims to provide a vehicle information display device that can display high-resolution video information through the windshield (and further the rear windshield or side windows) of the vehicle, which is the shield glass of the vehicle, instead of the conventional head-up display method. In that case, the displayed video information is visible to the passengers (including the driver) inside the vehicle, but not from the outside of the vehicle, or vice versa, i.e., visible from the outside of the vehicle but not from the passengers (including the driver) inside the vehicle. That is, the present invention aims to provide a vehicle information display device capable of one-way display. Further, it aims to provide a vehicle information display system using such a vehicle information display device.

Means for Solving the Problems

[0010] In the present invention, in order to achieve the above object, a display device mounted on a vehicle, comprising a display panel, and a light beam travels from the display panel toward a display area of the shield glass of the vehicle. The traveling direction of the light beam from the display panel is inclined in a direction away from the driver of the vehicle, and the display area of the shield glass is located at a position close to the lower end of the shield glass. A display device is provided.

Effects of the Invention

[0011] According to the present invention, there is an effect that a vehicle information display device capable of displaying high-resolution video information in one direction is provided, and further, a novel and highly usable vehicle information display system using such a vehicle information display device is provided.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings and the like. It should be noted that the present invention is not limited to the following description, and various changes and modifications can be made by those skilled in the art within the scope of the technical idea disclosed in this specification. Also, in all the drawings for explaining the present invention, those having the same function are given the same reference numerals, and the repeated description thereof may be omitted.

[0014] <Vehicle Information Display System> FIG. 1(a) is a top view of a vehicle information display device 100 according to an embodiment of the present invention when mounted on a vehicle, particularly an automobile. In the front part of the driver's seat of the vehicle body 1, there are a windshield 6, a rear windshield 6', side windows 6", etc. (collectively also referred to as "shield glass") as translucent projection members for projecting and displaying video light. In particular, the inclination angle of the windshield 6 with respect to the vehicle body varies depending on the type of the vehicle. The inventors also investigated this radius of curvature in order to realize an optimal virtual optical system. As a result, as shown in FIG. 1(b), the windshield 6 has different radii of curvature Rh in the horizontal direction parallel to the ground surface of the vehicle and Rv in the vertical direction perpendicular to the horizontal axis, and it was found that the following relationship generally holds between Rh and Rv. Rh > Rv It was also found that the difference in the radius of curvature, that is, Rh with respect to Rv, is often in the range of 1.5 to 2.5 times.

[0015] The present invention relates to a system that, when a driver drives a vehicle through a front glass 6, a rear glass 6', and / or a side glass 6'' that constitute a part of the vehicle, allows the driver and passengers inside the vehicle to be monitored for video information, and on the other hand, can display video information to the outside of the vehicle. As a result, the driver and passengers can appropriately display necessary information in a display area such as the front glass 6 and monitor it inside the vehicle, but on the other hand, the information cannot be monitored from the outside of the vehicle. Alternatively, video information can be displayed to the outside of the vehicle through the rear glass 6' or the side glass 6'' (which may include the front glass 6). The displayed information can be monitored from the outside, but cannot be monitored from inside the vehicle, and does not interfere with driving without preventing the driver and passengers from monitoring the external scenery.

[0016] In addition, natural light such as sunlight is not only light in a wide wavelength range from ultraviolet to infrared as shown in FIG. 16, but also exists in a state where two types of polarized light directions (hereinafter referred to as S-polarized light and P-polarized light), light with a vibration direction perpendicular to the light propagation direction and light with a horizontal direction, are mixed. In particular, in a region where the incident angle on the front glass 6 exceeds 50 degrees, as shown in FIG. 15, the reflectance on the glass surface is different for S-polarized light, P-polarized light, and further depending on the incident angle.

[0017] Therefore, in the present embodiment, based on the findings of the above-mentioned inventor, that is, considering that most of the sunlight entering through the front glass 6 is a P-polarized light component, in order to suppress external light including sunlight entering the information display device, in particular, reducing the P-wave component is effective. In addition, it was confirmed that it is effective to use the S-wave component as the video light projected from the information display device.

[0018] Subsequently, with reference to FIG. 2, the specific configuration of the vehicle information display device that constitutes the vehicle information display system according to the present invention will be described in detail below with reference to the drawings.

[0019] <Specific Configuration 1 of Vehicle Information Display Device> Figure 2 shows the overall configuration of a vehicle information display device 100 that displays video information on a part of the external landscape monitored by the driver through a windshield 6, which is a transparent projection member constituting a part of the vehicle. Here, the windshield 6 is divided into a plurality of regions, and the video light from a video display device (video projection device) 48 is diffused and reflected by the windshield 6 in a part of the region (in this example, the lower part of the windshield 6), and the reflected image is directly monitored by the driver and passengers in one direction. As a result, the driver and passengers can appropriately display and monitor the necessary information in the display area of the windshield 6, while on the other hand, the information cannot be visually recognized from outside the vehicle.

[0020] In the vehicle information display device 100, as shown in FIG. 2, the video display device 48 projects, for example, high-resolution map information (video of a large high-resolution video display device) from a smartphone 300 or the like onto the inner surface of the windshield 6 through an optical direction conversion panel 54 and a protective cover 50, and reflects it toward the eyes 8 of the monitor (driver) by a transparent sheet (film) 51 provided on the surface of the windshield 6, thereby displaying a video on the windshield 6.

[0021] Note that in this example, an example of using a smartphone 300, which is a high-performance portable terminal device equipped with a navigation function for providing map information and the like, is shown. The display screen from the smartphone 300 can be input via a wired connection terminal or wirelessly via Bluetooth (registered trademark) or Wifi (registered trademark) or the like to display the video. Thus, the driver can monitor high-resolution video information using the vehicle information display device 100.

[0022] Although not shown here, the smartphone 300, like the video display device 48, includes a control unit composed of a CPU (Central Processing Unit), various solid-state memories such as a work memory and a RAM and a ROM having functions as information storage and memory means, and of course has a function of generating necessary video and displaying it on its display device (liquid crystal display).

[0023] Furthermore, a more specific configuration of the vehicle information display device 100 will be described with reference to FIG. 3. The liquid crystal display panel (video display element) 52 constituting the video display device 48 is composed of, for example, a relatively large liquid crystal display panel with a screen size exceeding 6 inches. Generally, since the radius of curvature of the front glass 6 often varies partially, uneven (vertical and horizontal) distortion occurs in the displayed video depending on the location where the video is reflected. Therefore, distortion correction is required to obtain a correct video when viewing the reflected image from the monitoring direction. To perform correction at a practically problem-free level by this distortion correction, the resolution of the panel needs to be 1280×720 dots or more.

[0024] In addition, the video display device 48 includes a light source device 101 constituting its light source together with the above-described liquid crystal display panel 52. In FIG. 3, the light source device 101 is shown as a developed perspective view below the liquid crystal display panel 52.

[0025] As shown in FIG. 3, this liquid crystal display panel (video display element) 52 obtains a strongly directional illumination light beam from the light source device 101 which is a backlight device, and emits modulated video light according to the input video signal toward the transparent sheet 51 provided on the front glass 6.

[0026] Also, in FIG. 3, the vehicle information display device 100, together with the liquid crystal display panel 52 that constitutes the video display device 48, further includes an optical direction conversion panel 54 that controls the directivity characteristics of the emitted light beam 30 from the light source device 101, and, if necessary, a sandwiching angle diffuser plate. That is, polarizing plates are provided on both sides of the liquid crystal display panel 52, and video light of a specific polarization modulates the intensity of light according to a video signal and is emitted. As a result, a high-resolution video (video of a large high-resolution video display device) from a smartphone 300 or the like is projected toward the windshield 6 via the optical direction conversion panel 54, and is reflected toward the eyes 8 of the monitor (driver) via the transparent sheet 51 provided on its surface.

[0027] As shown in FIG. 4, the light source device 101 is, for example, formed of plastic or the like, and is composed of a case of the light source device 101 (see FIG. 3) that houses an LED element, a collimator, a composite diffuser block, a light guide, etc., which will be described in detail later. On its upper surface, a liquid crystal display panel 52 that constitutes the video display device 48 is attached. Also, on one side surface of the case of the light source device 101, LED (Light Emitting Diode) elements 14a, 14b, which are semiconductor light sources, and an LED substrate 102 on which its control circuit is mounted are attached, and on the outer surface of the LED substrate 102, a heat sink 103, which is a member for cooling the heat generated by the LED elements and the control circuit, is attached (see FIG. 3).

[0028] On the other hand, the video display device 48 attached to the upper surface of the light source device case 101 is composed of a liquid crystal display panel frame, a liquid crystal display panel 52 attached to the frame, and an FPC (Flexible Printed Circuits) 403 (see FIG. 3) electrically connected to the liquid crystal display panel 52, etc. That is, the liquid crystal display panel 52, which is a liquid crystal display element, generates a display video by modulating the intensity of transmitted light based on a control signal from a control circuit (not shown here) that constitutes an electronic device, together with the LED elements 14a, 14b, which are solid light sources. This will be described in detail later.

[0029] Next, an example of the configuration of the light source device 101, that is, the optical system housed in the light source device case, will be described in detail below with reference to FIG. 5 together with FIG. 4.

[0030] FIGS. 4 and 5 show a plurality (two in this example) of LED elements 14a and 14b that constitute the light source, and these are attached to the LED collimator 15 at predetermined positions. Note that each of these LED collimators 15 is formed of a light-transmissive resin such as acrylic, for example. And as shown in FIG. 5(b), this LED collimator 15 has an outer peripheral surface 156 in a conical convex shape obtained by rotating a parabolic cross-section, and at the top of the LED collimator 15, it has a concave portion 153 formed with a convex portion (that is, a convex lens surface) 157 at its central portion. Also, at the central portion of the flat surface portion of the LED collimator 15, it has a convex lens surface (or it may be a concave lens surface recessed inward) 154 that protrudes outward. Note that the parabolic surface 156 that forms the conical outer peripheral surface of the LED collimator 15 is set within an angle range that allows the light emitted from the LED element 14a in the peripheral direction to be totally reflected inside it, or a reflecting surface is formed.

[0031] On the other hand, the LED elements 14a and 14b are respectively arranged at predetermined positions on the surface of a so-called LED substrate 102, which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the LED collimator 15 such that the LED element 14a or the LED element 14b on its surface is respectively located at the central portion of the concave portion 153.

[0032] According to such a configuration, among the light emitted from the LED element 14a or the LED element 14b by the above-described LED collimator 15, in particular, the light emitted upward (in the right direction in the figure) from the central portion thereof is condensed by the two convex lens surfaces 157 and 154 forming the outer shape of the LED collimator 15 and becomes parallel light. Further, the light emitted from other portions in the peripheral direction is reflected by the parabolic surface forming the conical outer peripheral surface of the LED collimator 15 and is similarly condensed to become parallel light. In other words, according to the LED collimator 15 having a convex lens formed in the central portion and a parabolic surface formed in the peripheral portion thereof, almost all of the light generated by the LED element 14a or the LED element 14b can be taken out as parallel light, and the utilization efficiency of the generated light can be improved.

[0033] Note that a polarization conversion element 21, which will be described in detail below, is provided on the light emission side of the LED collimator 15. As is clear from FIG. 5(a), this polarization conversion element 21 is formed by combining a columnar (hereinafter, parallelogram column) light transmissive member having a parallelogram cross section and a columnar (hereinafter, triangular column) light transmissive member having a triangular cross section, and is configured by arranging a plurality of them in an array parallel to a plane orthogonal to the optical axis of the parallel light from the LED collimator 15. Further, a polarization beam splitter (hereinafter abbreviated as "PBS") film 211 and a reflection film 212 are alternately provided at the interfaces between adjacent light transmissive members arranged in this array. In addition, a 1 / 2λ phase plate 213 is provided on the emission surface from which the light that has entered the polarization conversion element 21 and passed through the PBS film 211 is emitted.

[0034] A rectangular composite diffusion block 16 shown in FIG. 5(a) is further provided on the emission surface of this polarization conversion element 21. That is, the light emitted from the LED element 14a or the LED element 14b becomes parallel light by the action of the LED collimator 15, enters the composite diffusion block 16, is diffused by the texture 161 on the emission side, and then reaches a light guide 17 described below.

[0035] The light guide 17 is a member formed of a light-transmitting resin such as acrylic into a rod shape with a substantially triangular cross section (see Fig. 5(b)). As is also clear from Figs. 4 and 5, a light guide light incident portion (light guide light incident surface) 171 that faces the light exit surface of the synthetic diffusion block 16 via a first diffusion plate 18a, a light guide light reflecting portion (light guide light reflecting surface) 172 that forms an inclined surface, and a light guide light exit portion (light guide light exit surface) 173 that faces the liquid crystal display panel 52 of the liquid crystal display element via a second diffusion plate 18b.

[0036] As shown in Fig. 4, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a zigzag shape on the light guide light reflecting portion 172 of the light guide 17. The reflecting surface 172a (the line segment rising to the upper right in the figure) forms an angle αn (n is a natural number, and in this example, for example, it is 1 to 130) with the horizontal plane indicated by the dashed line in the figure. As an example, here, αn is set to 43 degrees or less (however, 0 degrees or more).

[0037] The light guide light incident portion 171 is formed in a curved convex shape inclined toward the light source side. According to this, the parallel light from the light exit surface of the synthetic diffusion block 16 is diffused through the first diffusion plate 18a and enters the light guide 17. As is also clear from Fig. 4, the light guide light incident portion 171 slightly bends (deflects) upward and reaches the light guide light reflecting portion 172, where it is reflected and reaches the liquid crystal display panel 52 provided on the upper light exit surface of the figure.

[0038] As described in detail above, according to the video display device 48 of the vehicle information display device 100 described above, while improving the light utilization efficiency and its uniform illumination characteristics, it is possible to manufacture it in a small size and at low cost, including the modularized S-polarized light source device. In the above description, the polarization conversion element 21 is described as being attached after the LED collimator 15. However, it is obvious to those skilled in the art that the present embodiment is not limited thereto, and the same operations and effects can also be obtained by providing it in the optical path leading to the liquid crystal display panel.

[0039] Note that in the light reflector 172 of the light guide, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape. The illumination light beam is totally reflected on each reflecting surface 172a and directed upward. Further, a sandwiching angle diffusion plate is provided in the light emitting portion 173 of the light guide, and the light beam is incident on the light direction conversion panel 54 that controls the directivity as a substantially parallel diffusion light beam, and is incident on the liquid crystal display panel 52 from an oblique direction. In this embodiment, the light direction conversion panel 54 is provided between the light emitting surface 173 of the light guide and the liquid crystal display panel 52. Needless to say, the same effect can be obtained if it is provided on the emitting surface of the liquid crystal display panel 52.

[0040] <Light direction conversion panel> FIG. 6 is a schematic explanatory diagram for explaining the principle of the light direction conversion panel 54 provided on the upper surface of the above-described video display device 48, which forms a part of the vehicle information display device 100 according to an embodiment of the present invention. The light beam from the light guide 17 of the light source device 101 described above is incident from the incident surface (the lower surface in the figure) of the light direction conversion panel 54, and the light beam is refracted in a desired direction θ3 by the lens action of the linear Fresnel lens provided on the emission surface (the upper surface in the figure). At this time, the desired direction θ3 is uniquely derived from Snell's law based on the incident angle θ2 of the light beam to the Fresnel lens, the Fresnel angle θ0 of the Fresnel lens, and the refractive index n of the base material.

[0041] As a result, directivity can be given to the substantially parallel light beam from the light guide in a desired direction. That is, the video light, which is the light from the liquid crystal display panel 52 constituting the information display device 48, is not visually recognized by the driver or passengers inside the vehicle, and goes toward the transparent sheet 51 provided on the front glass 6 described below. Originally, thereafter, the video light is reflected and diffused in one direction by the transparent sheet 51, and the reflected image is visually recognized by the driver.

[0042] That is, with this light direction conversion panel 54, the video light from the video display device 48 (see FIGS. 2 or 3) itself is not directly visible from inside the vehicle, and thus does not interfere with driving. Only the reflected image formed by the reflected light is monitored by the driver and passengers. Note that a light-absorbing paint or pigment is provided on the joint surface 88 of the Fresnel lens to suppress the generation of light other than the light beam traveling in a desired direction. As a result, unnecessary light does not mix into the video light reflected by the windshield, and the imaging performance is not impaired.

[0043] <Protective cover> FIG. 7 is a cross-sectional view showing a schematic configuration of a protective cover 50 provided on the upper surface of the light direction conversion panel 54 in contact with the dashboard 47. A black stripe 59 is provided on a part of the light-emitting side of the substantially transparent base material 56. In order to reduce the surface reflection of external light including sunlight, it is preferable to use a paint containing carbon black as the black paint for the black stripe 59. In addition, an antireflection film is provided on the part where the black stripe is not provided to suppress the surface reflection, so that the external light reflection on the surface of the protective cover 50 is significantly reduced, and the hindrance caused by the external light reflection is reduced when the driver drives the vehicle. On the other hand, in order to enhance the light-shielding performance against sunlight, it is preferable to endow the antireflection film with the property of reflecting near-infrared light and infrared light.

[0044] On the other hand, a film or a filter 50a that absorbs or reflects the P-wave component of the sunlight beam is formed or adhered on the light-incident side of the substantially transparent base material 56. As a result, since the P-wave component of the sunlight does not enter the video display device 48, the reliability regarding light resistance and heat resistance is significantly improved. On the other hand, since it also has the characteristic of a filter that selectively transmits the S-polarized video light output from the video display device 48, the contrast performance of the obtained video is significantly improved.

[0045] Since the video source that constitutes the above-described video display device 48 is the liquid crystal display panel 52, when the driver is wearing polarized sunglasses, there is a problem that a specific polarization wave is blocked and the video cannot be seen. To prevent this, in the protective cover 50 provided on the light emission side of the video display device 48, a wave plate 50b such as a λ / 4 plate, a λ / 8 plate, or a λ / 16 plate is disposed between the film or film 50a and the base material 56. By providing the wave plate 50b, the polarization direction of the light beam can be aligned in a specific direction, and the video light can be set to an optimal polarization angle, and the polarization direction of the polarized sunglasses and the desired amount of polarization axis can be shifted.

[0046] On the other hand, even for the same polarization, the absorption axis is rotated. For example, by shifting the absorption axis of the polarizing plate on the liquid crystal panel emission side by 30 degrees or more with respect to the absorption axis of the polarized sunglasses, the absorption becomes about 50%, and thus the problem that the video cannot be seen can be solved.

[0047] Also, when the polarization axis is rotated to approach circular polarization, the polarization axis of the video light from the information display device 48 rotates from S polarization. Therefore, since the reflectance by the front glass 6 decreases and the brightness of the video decreases, it is advisable to select by taking a balance between the two.

[0048] <Unidirectional transparent sheet> Next, the configuration and operation of the transparent sheet 51 will be described with reference to FIG. 8. Sunlight incident on the windshield 6 (horizontally arranged for convenience of explanation) from an oblique direction has its S-polarized wave reflected and its P-polarized wave transmitted toward the transparent sheet 51. The transparent sheet 51 is composed of a polarizing plate 57 that transmits S-waves, a transparent diffusing sheet material 55, and a retardation plate 58. This transparent sheet 51 is a film obtained by stretching while melting a thermoplastic polymer in which nanoparticles of zirconium or diamond with a high refractive index are dispersed. For example, by using "Kaleidoscreen" manufactured by JXTG Energy Corporation (see Patent Document 3 mentioned above), it is transparent when no image is being displayed, and it does not interfere with the driver's monitoring of the scenery outside (outside the vehicle). On the other hand, when an image is being displayed, it diffuses and reflects the image light, thereby making it possible to realize a unidirectional display that allows the driver and passengers to visually recognize the image information. At this time, there is no practical problem as long as the haze, which is defined by the ratio of the diffusion transmittance to the parallel light transmittance of the transparent sheet 51, is 10% or less, but it is preferably 4% or less. On the other hand, the HAZU of a windshield for automobiles is 2% or less.

[0049] Since the image light from the image display device 48 is S-polarized, it has a high reflectance when incident obliquely, scatters inside the aforementioned transparent diffusing sheet material 55, and is emitted toward the viewer. On the other hand, a part of the image light has its polarization direction disrupted by scattering, diffusely transmits through the transparent diffusing sheet 55, and is emitted toward the windshield 6. Since the refractive index difference is small at the incident surface of the windshield 6, the level of double images generated by the reflected light is low. In contrast, since the intensity of the reflected light generated at the exit surface of the windshield 6 (the surface in contact with the outside) is mostly composed of the S-polarization component, the reflectance is large. The image light reflected from this surface passes through the polarizing plate 57 again after reflection and is absorbed, so it does not return to the viewer side. Therefore, no double images are generated due to the reflected image on the windshield 6, and the image quality is significantly improved. Needless to say, similarly, the same effect can be obtained by attaching the aforementioned transparent sheet 51 to the combiner instead of the windshield 6 as the reflection surface of the image.

[0050] According to the transparent sheet 51 described above, as shown in FIG. 8, in the daytime under predetermined conditions, the P-polarized sunlight component that has passed through the windshield (and then also passes through the combiner in the combiner method) is absorbed in front of the vehicle information display device 100, the light direction conversion panel 54 provided on its upper surface, and the protective cover 50, so that it is possible to prevent it from returning to the liquid crystal display panel and the polarizing plate.

[0051] <Vehicle Information Display System> According to the vehicle information display system provided with the vehicle information display device 100 described in detail above, as indicated by the arrow in FIG. 3, a large high-resolution video display device 48 is provided at the position of the dashboard 47 (see FIG. 2) corresponding to the video display area in the lower end area of the front windshield 6, which is a shield glass, and the display video is reflected by the front windshield, so that the reflected image can be directly monitored by the driver and passengers.

[0052] An example of the arrangement inside the cockpit of an automobile in which the vehicle information display device 100 of the present embodiment including the above-described video display device 48 and transparent sheet 51 is arranged is shown in FIG. 9. FIG. 9(a) shows a system corresponding to an automobile with a steering wheel arranged on the left side, and FIG. 9(b) shows a system corresponding to an automobile with a steering wheel arranged on the right side. In the image display area (corresponding to the area where the transparent sheet 51 is pasted) in the figure, video information is reflected by the front windshield 6 using the vehicle information display device 100, and the reflected image is monitored by the driver. At this time, the image display area is preferably set to a range or area that does not interfere with the driver's monitoring of the external scenery of the vehicle, such as the range where the bonnet of the own vehicle indicated by the broken line in the figure is monitored.

[0053] As shown in the figure, the above-described vehicle information display device 100 is disposed inside the dashboard 47 between the windshield 6 and the steering wheel 43 in the order from the windshield 6 to the video display device 48 toward the steering wheel 43. As a result, when the driver drives the vehicle, an external landscape monitored through the windshield 6, that is, in a partial region of the windshield 6, a vehicle information display system can be provided in which the image of a large-size high-resolution video display device is reflected by the windshield 6 by the vehicle information display device 100 so that the driver and passengers can monitor the reflected image.

[0054] Note that the rearview mirror 71 in FIG. 9 is provided with a camera 72 for monitoring the state of the driver and the interior of the vehicle, and it would be possible to control, for example, the emission direction of the video light from the above-described information display device according to the height of the driver's eyes.

[0055] FIG. 10 is a schematic diagram showing an example of a system that, in addition to the above-described vehicle information display device 100, provides video information to a passenger in the passenger seat, and further, a system equipped with a head-up display (HUD) device (FIG. 10(b)). FIG. 10(a) corresponds to a vehicle with the steering wheel 43 arranged on the left side, similar to FIG. 9, and FIG. 10(b) corresponds to a vehicle with the steering wheel 43 arranged on the right side.

[0056] In FIG. 10(a), in addition to the vehicle information display device 100 on the driver's seat side described above, a second vehicle information display device 100' is further installed on the passenger seat side, and an image display area (2) that can be monitored by the passenger is set in a partial region (the right side in the figure) of the windshield 6 together with the image display area (1) that can be monitored by the driver. In addition, in FIG. 10(b), a head-up display (HUD) type information display device (head-up display device, hereinafter referred to as "HUD device") 700 is further installed. An example is shown in which an image display area (2) is set for the passenger, and in addition to the image display area (1) by the information display device 48, a HUD display area by the HUD device 700 is set for the driver.

[0057] As the HUD device 700, a known general device can be adopted. Here, as an example, its outline will be described below.

[0058] FIG. 11 is a schematic configuration diagram showing the HUD device 700 including its peripheral device configuration. Here, in order to form a virtual image V1 in front of the host vehicle at the line of sight (eye point) of the driver 8, various information reflected by the projection member 6 (the inner surface of the windshield) is displayed as a virtual image VI (Virtual Image).

[0059] In the HUD device 700, there are provided an image display device 704 that projects image light for displaying information, and a correction lens element 702 for correcting distortion and aberration generated when forming a virtual image with a concave (free-form surface) mirror 701 for the image displayed on the image display device 704. The image light beam from this information display device 700 is emitted from an opening (not shown) toward the windshield 6.

[0060] Further, the HUD device 700 further includes a control device 740 that controls the image display device 704 and its backlight. Note that the optical components including the image display device 704 and the backlight are a virtual image optical system and include a concave mirror 701 that reflects light. Also, the light reflected by this optical component is reflected by the windshield 6, which is the projection member, and travels toward the line of sight 8 of the driver. As the image display device 704, for example, in addition to an LCD (Liquid Crystal Display) having a backlight, there is a self-luminous VFD (Vacuum Flourescent Display) and the like.

[0061] In addition, the illustrated control device 740 that constitutes such a HUD device 700 acquires, from the navigation system 761, various types of information such as the speed limit, number of lanes of the road corresponding to the current position where the host vehicle is traveling, and the planned travel route of the host vehicle set in the navigation system 761, as foreground information (i.e., information to be displayed in front of the host vehicle by a virtual image). Further, the driving support ECU 762 is a control device for realizing driving support control by controlling the drive system and the control system according to obstacles detected as a result of monitoring by the peripheral monitoring device 763. Such driving support control includes, for example, well-known technologies such as cruise control, adaptive cruise control, pre-crash safety, and lane keeping assist. The peripheral monitoring device 763 shown in FIG. 11 is a device that monitors the situation around the host vehicle. As an example, it includes a camera that detects an object existing around the host vehicle based on an image of the periphery of the host vehicle, and a detection device that detects an object existing around the host vehicle based on the result of transmitting and receiving detection waves.

[0062] The control device 740 of the HUD device 700 described above acquires information (for example, the distance to the preceding vehicle, the azimuth of the preceding vehicle, the positions where obstacles and signs exist, etc.) from such a driving support ECU 762 as foreground information. Further, an ignition (IG) signal and host vehicle state information are input to this control device 740. Among these pieces of information, the host vehicle state information is information acquired as vehicle information and does not require a high-resolution display. For example, it includes warning information indicating that a predefined abnormal state has occurred, such as the remaining fuel amount of the internal combustion engine and the temperature of the cooling water. It also includes the operation result of the direction indicator, the traveling speed of the host vehicle, and further, shift position information, etc. The control device 740 described above is activated when an ignition signal is input. Note that the projection member may be any member onto which information is projected, and it may be not only the front glass 6 but also a combiner or the like, as long as it forms a virtual image in front of the host vehicle in the driver's line of sight 8 and allows the driver to visually recognize it.

[0063] <Modification Example of Vehicle Information Display System: External Display> According to the embodiments described in detail above, when a driver drives his / her own vehicle, necessary video information can be displayed and monitored in high resolution in one direction for the driver and passengers inside the vehicle via the front glass 6 as a projection member that constitutes the vehicle, i.e., the windshield. At this time, the information cannot be monitored from the outside of the vehicle. However, the vehicle information display system according to an embodiment of the present invention is not limited to the above-described embodiments, and it is also possible to display video information to the outside of the vehicle. That is, not only the above-described front glass 6 but also the rear glass 6' and side glass 6" which are windshield glasses can be used to display video information inside or outside the vehicle in the same manner.

[0064] For example, in the vehicle information display system of the present embodiment, information indicating the state of the vehicle such as "empty car" is displayed not only on a part of the front glass 6 of a taxi but also on the rear glass 6' and side glass 6", or other information such as information promotion and advertisements can also be displayed to the outside of the vehicle. Also, in vehicles such as buses and trains, information such as their routes and destinations can be displayed in one direction to the outside of the vehicle via the front glass, rear glass, and side glass. Below, the configuration of the vehicle information display device 100" when information is displayed to the outside will be described.

[0065] In Fig. 12, a system is shown that displays necessary video information in one direction with high resolution to the outside of the vehicle through the front glass 6 as the projection member. More specifically, here, an example of displaying the state of a taxi (such as "available") on the front glass of a taxi is shown. In this modification, in the configuration shown in Fig. 2, as the transparent sheet 51' provided on the surface of the front glass 6, the video light from the video display device 48 is diffused and transmitted by the front glass 6, and the video is transmitted and displayed to the outside of the vehicle as shown by the arrow in the figure, for example, so that pedestrians and the like can monitor it. As a result, the driver and passengers can display the necessary information on the front glass 6 to the outside of the vehicle, but the display does not interfere with the monitoring of the outside scenery monitored from inside the vehicle and does not interfere with the driving of the driver.

[0066] Note that the transparent sheet 51' is composed of a polarizing plate 57 that transmits S waves and a transparent diffusion sheet material 55, similar to the transparent sheet 51. Here, a film obtained by stretching while melting a thermoplastic polymer in which nanoparticles of zirconium or diamond with a high refractive index are dispersed, for example, "Kaleidoscreen" manufactured by JXTG Energy Co., Ltd. (see Patent Document 2 described above) is used. When no video is being displayed, it is transparent, while when video is being displayed, it diffuses and transmits the video light. As a result, it is possible to realize a one-way display that allows the driver and passengers to monitor the outside scenery without visual recognition of the video information and without interfering with the monitoring of the outside scenery, and only displays information to the outside.

[0067] Fig. 13 shows the operation of the transparent sheet 51' in this case. As is clear from this figure, the transparent sheet 51' is composed of a polarizing plate 57, a transparent diffusion sheet material 55, and a retardation plate 58. Similar to the transparent sheet 51, the sunlight incident from an oblique direction is such that its S polarized wave is reflected, while the P polarized wave is transmitted, thereby reducing the illuminance of the sunlight. At this time, by rotating the polarization axis of the P polarization by the retardation plate 58, a part of the sunlight is absorbed by the polarizing plate 57. As a result, the damage received by the video display device 48 due to sunlight can be dispersed.

[0068] On the other hand, the image light diffused outside the vehicle by the action of the transparent diffusing sheet material 55 is reflected by the rear glass 6' and returns inside the vehicle. This light becomes an obstacle to driving as it obstructs the driver's view. Therefore, in this embodiment, a retardation plate 58 is disposed between the rear glass 6' and the polarizing plate 57 to absorb the reflected light with the polarizing plate, so that the information by the image light is displayed in one direction toward the outside of the vehicle without being visually recognized by the driver or passengers inside the vehicle. At that time, the information by the image light does not interfere with the driving by preventing the driver or passengers inside the vehicle from monitoring the scenery outside the vehicle. The haze defined by the ratio of the diffusion transmittance to the parallel light transmittance of the transparent sheet 51' described above is practically not a problem if it is 10% or less, but preferably 4% or less. On the other hand, the HAZU of the windshield for automobiles is 2% or less.

[0069] As described above, the display of information to the outside of the vehicle using a part of the shield glass such as the front glass 6, further the rear glass 6' or the side glass 6", etc. is suitable for displaying information such as "Vacant" indicating the vacant state of the taxi described above to pedestrians on the road. Further, as described above, the vehicle information display device according to an embodiment of the present invention not only displays video information in one direction on the front glass 6, but also, for example, in large vehicles such as buses and trains, using a projection member such as the rear glass 6' or the side glass 6" (see FIG. 1) which is the shield glass constituting the vehicle, it is also possible to display various types of information including advertisements, announcements, etc. Hereinafter, the configuration and operation of the vehicle information display system when displaying information to the outside of the vehicle will be described.

[0070] FIG. 14 shows, as another modification example, a projection member that forms part of a vehicle. Information is displayed, for example, to pedestrians outside the vehicle through the rear windshield 6' that forms part of the vehicle 1. As a result, the driver and passengers can monitor the necessary information on the front windshield 6 described above (see FIG. 9). At the same time, information can also be displayed outside the vehicle by the rear windshield 6'. Note that the driver and passengers cannot monitor the information displayed outside, so it does not obstruct the driver's field of vision. That is, the display of information outside the vehicle does not prevent the driver and passengers inside the vehicle from monitoring the external scenery.

[0071] In this example, as shown in FIGS. 14(a) and 14(b), the video display device 48 is arranged below the rear windshield 6' which is a projection member forming part of the vehicle, and the video light is projected toward an image display area set on the entire surface or a part of the rear windshield 6' to display video information.

[0072] Note that in this example as well, it is natural that the transparent sheet 51' shown in FIG. 13 described above is provided in the image display area of the rear windshield 6'. In addition, as a projection member that displays video information in one direction toward the outside of the vehicle, it is not limited to the above-described front windshield 6 and rear windshield 6'. For example, it is also possible to use the side glass 6" (see FIG. 1) that forms part of the side of the vehicle. In that case, although not shown here, the video display device 48 is arranged in a member near the side glass 6" (for example, an adjacent ceiling surface or a part of the window frame), and it is natural that the transparent sheet 51' shown in FIG. 13 is provided in the image display area of the side glass 6". The display of information on such a side glass 6" would be suitable, for example, for displaying messages such as "Sorry to keep you waiting" or "Please board" to passengers on the road in a taxi.

[0073] In addition, in the examples described above, the vehicle information display devices 100, 100', and 100" that display video information in one direction to the outside or inside of the vehicle via the front glass 6, rear glass 6', and side glass 6", which are the projection members constituting the vehicle, have been described. However, the present invention is not limited to these, and for example, it is also possible to appropriately combine a vehicle information display device 100 that displays information inside the vehicle with a vehicle information display device 100' that displays information to the outside of the vehicle. According to this, for example, when applied to buses, trains, etc., which are public transportation, it is possible to display various types of information including advertisements, announcements, etc. to the public outside the vehicle via the rear glass 6' and side glass 6" (however, not visible from inside the vehicle), enabling effective display of information to the public.

[0074] Although various embodiments have been described in detail above, however, the present invention is not limited to only the above-described embodiments and includes various modifications. For example, the above-described embodiments have described the entire system in detail for easy understanding of the present invention and are not necessarily limited to those having all the configurations described. Also, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add, delete, or replace other configurations for a part of the configuration of each embodiment.

Explanation of Reference Numerals

[0075] 1... Automobile (vehicle) body, 6... Front glass, 6'... Rear glass, 6"... Side glass, 100... Vehicle information display device, 101... Light source device, 48... Video display device (video projection device), 50... Protection cover, 50a... Film or sheet, 50b... Wave plate, 51... Transparent sheet (film), 52... Liquid crystal display panel (video display element), 54... Light direction conversion panel, 55... Transparent diffusion sheet material, 56... Base material, 57... Polarizing plate, 58... Retardation plate, 59... Black stripe, 300... Smartphone.

Claims

1. A display device mounted on a vehicle, comprising a display panel, wherein a light beam travels from the display panel toward a display area of a windshield of the vehicle, the traveling direction of the light beam from the display panel is inclined in a direction away from a driver of the vehicle, the display area of the windshield is located at a position close to a lower end of the windshield, display device.

2. The display device according to claim 1, wherein a protection cover is provided on the display panel, display device.

3. The display device according to claim 2, wherein the protection cover has a film or a sheet that absorbs or reflects a linearly polarized light component from outside the vehicle, display device.

4. The display device according to claim 1, wherein a retardation plate is provided on an emission side of the display panel, display device.

5. The display device according to claim 1, wherein a linear Fresnel sheet is disposed between the display panel and the windshield, display device.

6. The display device according to claim 5, wherein light absorption surfaces are periodically arranged on the linear Fresnel sheet, display device.

7. The display device according to claim 1, wherein image light from the display panel cannot be directly visually recognized by a driver of the vehicle, display device.

8. The display device according to claim 1, wherein a resolution of the display panel is 1280×720 pixels or more, display device.

9. The display device according to claim 1, comprising a head-up display, wherein a head-up display display area viewed from a driver of the vehicle is located at a position different from the display area, display device.

10. The display device according to claim 1, comprising a second display panel different from the display panel, wherein a light beam travels from the second display panel toward a second display area of the windshield, the second display area of the windshield is located at a position on a side close to a lower end of the windshield and at a position different from the display area in a left-right direction as viewed from a driver of the vehicle, display device.

11. The display device according to claim 10, comprising a head-up display, wherein a head-up display display area viewed from a driver of the vehicle is located at a position different from both the display area and the second display area, display device.

Images