Indication 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 front glass, rear glass, side glass, etc. of an automobile, train, aircraft, etc. (hereinafter collectively referred to as "vehicles"), or a combiner, etc., and displays it. In particular, the present invention relates to a vehicle information display device and a vehicle information display system capable of reflecting or transmitting video information through a front glass, rear glass, etc., and displaying it in one direction inside or outside the vehicle.

Background Art

[0002] A so-called head-up display (HUD) device that projects video light onto the front glass or combiner of an automobile to form a virtual image and displays traffic information such as route information and traffic jam information, or automobile information such as fuel remaining amount and cooling water 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 visible 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] 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 or fine particles is already known from Patent Documents 2 and 3 below.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] The conventional head-up display type vehicle information display system described above displays augmented reality (AR) information, which is a virtual image, so as not to obstruct the driver's view of the outside of the vehicle. However, when displaying information such as maps, the displayed map information may obstruct the driver's view of the outside. Furthermore, while it is desirable to expand the displayable area in such vehicle information display systems, it is also required that the virtual image be high resolution and highly visible. For this reason, liquid crystal display elements (liquid crystal display panels) are often used because high-quality images can be easily obtained and are inexpensive. On the other hand, in order to miniaturize the set, small liquid crystal display elements are used, which results in insufficient resolution of the projected image, and a new challenge has become clear: it is unsuitable for displaying high-resolution images, such as those shown on smartphones.

[0007] Furthermore, such head-up display type vehicle information display devices are not intended to display video information to the outside of the vehicle. Therefore, if it is necessary to display video information to the outside of the vehicle, a display or other video display device is installed inside the vehicle, and the video information is displayed through the vehicle's glass. However, in that case, these video display devices obstruct the driver's view, which is undesirable from a safe driving perspective.

[0008] While prior art patent documents 2 and 3 disclose reflective or transparent screens equipped with a light-diffusing layer containing binders and fine particles used in information display devices, they do not provide any information on applications in vehicles related to the present invention, nor on specific methods, forms, or configurations for such applications.

[0009] The present invention aims to provide a vehicle information display device that replaces conventional head-up display type vehicle information display devices, and that can display high-resolution video information via the vehicle's shield glass, the windshield (and furthermore, the rear window and side windows), and in this case, the displayed video information is visible to passengers (including the driver) inside the vehicle, but not to those outside the vehicle, or conversely, is visible to those outside the vehicle, but not to those inside the vehicle, in other words, a vehicle information display device that enables so-called one-way display. Furthermore, the present invention aims to provide a vehicle information display system that utilizes such a vehicle information display device. [Means for solving the problem]

[0010] In order to achieve the above-mentioned objectives, A display device is provided for mounting on a vehicle, comprising a display panel, wherein a beam of light travels from the display panel toward a display area of ​​the vehicle's shield glass, the direction of travel of the beam of light from the display panel is inclined toward away from the driver of the vehicle, and the display area of ​​the shield glass is located near the lower end of the shield glass. [Effects of the Invention]

[0011] According to the present invention, a vehicle information display device capable of displaying high-resolution video information in one direction is provided, and furthermore, a novel and user-friendly vehicle information display system utilizing such a vehicle information display device is provided. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows a top view of an automobile equipped with a vehicle information display system according to one embodiment of the present invention, and a diagram illustrating the difference in the radius of curvature of the windshield. [Figure 2] This figure shows a schematic configuration of a vehicle information display device that constitutes a vehicle information display system according to one embodiment of the present invention. [Figure 3]This is a diagram for explaining a more specific configuration of the vehicle information display device. [Figure 4] This is a diagram showing a detailed configuration of a light source device of an image projection device that constitutes the vehicle information display device. [Figure 5] This is a diagram showing an example of an optical system of a light source device that constitutes the image projection device. [Figure 6] This is a diagram for explaining the principle of a light direction conversion panel that constitutes the vehicle information display device. [Figure 7] This is a cross-sectional view showing a schematic configuration of a protective cover that constitutes the vehicle information display device. [Figure 8] This is a diagram for explaining the configuration and operation of a unidirectional transparent sheet that constitutes the vehicle information display device. [Figure 9] This is a diagram showing an example of the arrangement inside the cockpit of an automobile where the vehicle information display device is arranged. [Figure 10] This is a diagram showing an example of the arrangement inside the cockpit of an automobile where the vehicle information display device is arranged. [Figure 11] This is a diagram showing a schematic configuration of a HUD-type information display device that constitutes a vehicle information display system according to an embodiment of the present invention. [Figure 12] This is a diagram for explaining a modification example of the vehicle information display system. [Figure 13] This is a diagram showing the action by a transparent sheet in a modification example of the vehicle information display system. [Figure 14] This is a diagram for explaining another modification example of the vehicle information display system. [Figure 15] This is a schematic diagram for explaining the change in the reflectance of glass due to the incident angle by S-polarized light and P-polarized light. [Figure 16] This is a diagram showing the spectral irradiance of sunlight.

Embodiments for Carrying Out the Invention

[0013] Embodiments of the present invention will be described in detail below with reference to the drawings and other figures. However, the present invention is not limited to the following description, and various modifications and changes are possible by those skilled in the art within the scope of the technical ideas disclosed herein. Furthermore, in all the figures used to illustrate the present invention, components having the same function are given the same reference numerals, and repeated descriptions may be omitted.

[0014] <Vehicle Information Display System> Figure 1(a) is a top view of a vehicle information display device 100 according to one embodiment of the present invention, when mounted on an automobile, train, aircraft, etc., particularly an automobile. In front of the driver's seat of the automobile body 1, there are translucent projection members such as a windshield 6, rear glass 6', and side glass 6'' (collectively called "shield glass") that project and display image light. In particular, the inclination angle of the windshield 6 relative to the vehicle body differs depending on the type of automobile. The inventors also investigated this radius of curvature in order to realize an optimal virtual image optical system. As a result, it was found that the radius of curvature of the windshield 6 differs between the horizontal radius of curvature Rh, which is horizontal to the ground surface of the automobile, and the radius of curvature Rv, which is perpendicular to the horizontal axis, as shown in Figure 1(b), and that the following relationship generally holds between Rh and Rv. Rh>Rv Furthermore, it was found that the difference in radius of curvature, specifically Rh relative to Rv, is often in the range of 1.5 to 2.5 times.

[0015] The present invention relates to a system that allows the driver and passengers to monitor video information inside the vehicle while driving, via the windshield 6, rear window 6', and / or side window 6'' which are projection members that constitute part of the vehicle, while simultaneously displaying video information to the outside of the vehicle. As a result, the driver and passengers can monitor necessary information within the vehicle by appropriately displaying it on a display area such as the windshield 6, but this information cannot be monitored from outside the vehicle. Alternatively, video information can be displayed to the outside of the vehicle via the rear window 6' or side window 6'' (which may include the windshield 6), and this displayed information can be monitored from the outside but not from inside the vehicle, without interfering with the driver or passengers' ability to monitor the external scenery and thus not interfering with driving.

[0016] Furthermore, natural light such as sunlight, as shown in Figure 16, not only contains light in a wide wavelength range from ultraviolet to infrared, but also exists in a mixed state with two types of polarization directions (hereinafter referred to as S-polarization and P-polarization): light with a vibration direction perpendicular to the direction of light propagation and light with a horizontal polarization direction. In particular, in regions where the incident angle to the windshield 6 exceeds 50 degrees, as shown in Figure 15, the reflectivity on the glass surface differs depending on whether the light is S-polarized or P-polarized, and also on the incident angle.

[0017] Therefore, in this embodiment, based on the inventor's findings described above, that is, considering that most of the sunlight entering through the windshield 6 is P-polarized, it was confirmed that reducing the P-wave component is particularly effective in suppressing external light, including sunlight, entering the information display device, and that in addition, it is effective to use the S-wave component as the image light projected from the information display device.

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

[0019] <Specific Configuration of Vehicle Information Display Device 1> Figure 2 shows the overall configuration of a vehicle information display device 100, which displays video information on a portion of the external landscape monitored by the driver via a transparent projection-receiving member, the windshield 6, which is part of the vehicle. Here, the windshield 6 is divided into multiple areas, and video light from the video display device (video projection device) 48 is diffused and reflected by the windshield 6 onto one of these areas (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 monitor the necessary information displayed on the display area of ​​the windshield 6 as needed, while this information cannot be seen from outside the vehicle.

[0020] In the vehicle information display device 100, as shown in Figure 2, the video display device 48 projects high-resolution map information (video from a large, high-resolution video display device) from, for example, a smartphone 300, onto the inner surface of the windshield 6 via a light direction conversion panel 54 and a protective cover 50, as will be described in more detail below. The video is then reflected towards the eyes 8 of the observer (driver) by a transparent sheet (film) 51 provided on the surface of the windshield 6, thereby displaying the video on the windshield 6.

[0021] In this example, we show a case where a high-performance mobile terminal device, a smartphone 300 equipped with a navigation function that provides map information, etc., is used. The display screen from the smartphone 300 can be input via a wired connection terminal or wirelessly via Bluetooth® or Wi-Fi®, and the image can be displayed. As a result, the driver can monitor high-resolution video information using the vehicle information display device 100.

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

[0023] Furthermore, the more specific configuration of the vehicle information display device 100 will be explained using Figure 3. The liquid crystal display panel (image display element) 52 that constitutes the image display device 48 is, for example, a relatively large liquid crystal display panel with a screen size exceeding 6 inches. Generally, the radius of curvature of the windshield 6 often differs in parts, so uneven distortion (vertical and horizontal) occurs in the displayed image depending on where the image is reflected. For this reason, distortion correction is necessary to obtain a correct image when the reflected image is viewed from the monitoring direction. In order to perform distortion correction at a level that does not cause practical problems, the panel resolution needs to be 1280 x 720 dots or higher.

[0024] Furthermore, the video display device 48, along with the liquid crystal display panel 52 described above, is equipped with a light source device 101 that constitutes its light source. In Figure 3, the light source device 101 is shown below the liquid crystal display panel 52 as an unfolded perspective view.

[0025] As shown in Figure 3, this liquid crystal display panel (image display element) 52 obtains a highly directional illumination beam from a light source device 101, which is a backlight device, and emits modulated image light in accordance with the input video signal toward the transparent sheet 51 provided on the windshield 6.

[0026] Furthermore, in Figure 3, the vehicle information display device 100 is configured to include, along with the liquid crystal display panel 52 that constitutes the video display device 48, an optical direction conversion panel 54 that controls the directional characteristics of the light beam 30 emitted from the light source device 101, and, if necessary, a narrow-angle diffuser. That is, polarizing plates are provided on both sides of the liquid crystal display panel 52, and the configuration is such that video light with a specific polarization is emitted after the intensity of the light is modulated by the video signal. As a result, high-resolution video from a smartphone 300 or the like (video from a large, high-resolution video display device) is projected toward the windshield 6 via the optical direction conversion panel 54 and reflected toward the eyes 8 of the observer (driver) via a transparent sheet 51 provided on its surface.

[0027] As shown in Figure 4, the light source device 101 consists of a case (see Figure 3) made of, for example, plastic, which houses LED elements, collimators, composite diffusion blocks, light guides, etc., which will be described in detail later. A liquid crystal display panel 52, which constitutes the image display device 48, is mounted on the top surface of the case. An LED substrate 102 on which semiconductor light source LED (Light Emitting Diode) elements 14a and 14b and their control circuits are mounted is attached to one side of the case of the light source device 101, and a heat sink 103, which is a component for cooling the heat generated by the LED elements and control circuits, is attached to the outer surface of the LED substrate 102 (see Figure 3).

[0028] On the other hand, the image display device 48 mounted on the top surface of the light source device case 101 consists of a liquid crystal display panel frame, a liquid crystal display panel 52 mounted on the frame, and an FPC (Flexible Printed Circuits) 403 (see Figure 3) electrically connected to the liquid crystal display panel 52. In other words, the liquid crystal display panel 52, which is a liquid crystal display element, generates a display image by modulating the intensity of transmitted light based on control signals from a control circuit (not shown here) that constitutes the electronic device, together with solid light source LED elements 14a and 14b, as will be explained in detail later.

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

[0030] Figures 4 and 5 show multiple (two in this example) LED elements 14a and 14b that constitute the light source, and these are attached to the LED collimator 15 at predetermined positions. Each of the LED collimators 15 is made of a translucent resin such as acrylic. As shown in Figure 5(b), the LED collimator 15 has a cone-shaped outer surface 156 obtained by rotating a parabolic cross section, and at the top of the LED collimator 15, there is a recess 153 with a convex portion (i.e., a convex lens surface) 157 formed in the center. In addition, the central part of the planar portion of the LED collimator 15 has a convex lens surface (or a concave lens surface) 154 that protrudes outward (or may be a concave lens surface that is recessed inward). The parabolic surface 156 that forms the cone-shaped outer surface of the LED collimator 15 is set within an angle range in which light emitted from the LED element 14a in the peripheral direction can be totally reflected inside it, or a reflective surface is formed thereon.

[0031] On the other hand, the LED elements 14a and 14b are each positioned at predetermined locations on the surface of the circuit board, so-called LED substrate 102. This LED substrate 102 is fixed to the LED collimator 15 such that the LED elements 14a or 14b on its surface are each positioned in the center of the recess 153.

[0032] With this configuration, the light emitted from the LED element 14a or LED element 14b, particularly the light emitted upward (to the right in the figure) from its central portion, is focused by the two convex lens surfaces 157 and 154 that form the outer shape of the LED collimator 15, becoming parallel light. Similarly, the light emitted from other parts toward the periphery is reflected by the parabolic surface that forms the conical outer surface of the LED collimator 15, and is also focused to become parallel light. In other words, with an LED collimator 15 having a convex lens in its center and a parabolic surface around its periphery, it becomes possible to extract almost all of the light generated by the LED element 14a or LED element 14b as parallel light, thereby improving the utilization efficiency of the generated light.

[0033] Furthermore, a polarization conversion element 21, which will be described in detail below, is provided on the light output side of the LED collimator 15. As is clear from Figure 5(a), this polarization conversion element 21 is constructed by combining a translucent columnar member with a parallelogram cross-section (hereinafter referred to as a parallelogram column) and a translucent columnar member with a triangular cross-section (hereinafter referred to as a triangular column), and arranging multiple such members in an array parallel to a plane perpendicular to the optical axis of the parallel light from the LED collimator 15. In addition, polarizing beam splitter (hereinafter abbreviated as "PBS") film 211 and reflective film 212 are alternately provided at the interfaces between adjacent translucent members arranged in this array, and a 1 / 2λ phase plate 213 is provided on the output surface from which light incident on the polarization conversion element 21 and transmitted through the PBS film 211 is emitted.

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

[0035] The light guide 17 is a rod-shaped member formed from a translucent resin such as acrylic, with a substantially triangular cross-section (see Figure 5(b)). As is clear from Figures 4 and 5, it comprises a light guide light incident portion (light guide light incident surface) 171 facing the emission surface of the composite diffusion block 16 via a first diffusion plate 18a, a light guide light reflecting portion (light guide light reflecting surface) 172 forming a slope, and a light guide light emission portion (light guide light emission surface) 173 facing the liquid crystal display panel 52 of the liquid crystal display element via a second diffusion plate 18b.

[0036] As shown in Figure 4, the light-reflecting portion 172 of the light guide 17 has numerous reflective surfaces 172a and connecting surfaces 172b alternately formed in a sawtooth pattern. The reflective surfaces 172a (sloping line segments in the figure) form αn (n is a natural number, for example, 1 to 130) with respect to the horizontal plane shown by the dashed line in the figure. As an example, here αn is set to 43 degrees or less (but greater than or equal to 0 degrees).

[0037] The light-indicating portion 171 of the light guide is formed in a curved convex shape that is inclined toward the light source. As a result, parallel light from the exit surface of the composite diffusion block 16 is diffused through the first diffusion plate 18a and incident on the light guide 17. As is clear from Figure 4, the light is slightly bent (deflected) upward by the light-indicating portion 171 of the light guide as it reaches the light-reflecting portion 172 of the light guide, where it is reflected and reaches the liquid crystal display panel 52 provided on the upper exit surface of the figure.

[0038] As detailed above, the video display device 48 of the vehicle information display device 100 described above improves light utilization efficiency and its uniform illumination characteristics, while also enabling the manufacture of a modular S-polarized wave light source device in a compact and low-cost form factor. In the above description, the polarization conversion element 21 was described as being installed after the LED collimator 15, but this embodiment is not limited to this, and it will be obvious to those skilled in the art that similar effects and benefits can be obtained by providing it in the optical path leading to the liquid crystal display panel.

[0039] Furthermore, the light guide's light-reflecting section 172 has numerous reflective surfaces 172a and connecting surfaces 172b formed alternately in a sawtooth pattern. The illumination beam is totally reflected on each reflective surface 172a and directed upward. In addition, a narrow-angle diffuser plate is provided on the light guide's light-emitting section 173 to control the directional characteristics as a substantially parallel diffuse beam, which is then incident on the light direction conversion panel 54 and 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 guide's light-emitting surface 173 and the liquid crystal display panel 52, but it goes without saying that the same effect can be obtained by providing it on the emission surface of the liquid crystal display panel 52.

[0040] <Optical Direction Conversion Panel> Figure 6 is a schematic diagram illustrating the principle of the optical direction conversion panel 54, which constitutes a part of the vehicle information display device 100 according to one embodiment of the present invention and is provided on the upper surface of the above-described video display device 48. The light beam from the light guide 17 of the above-described light source device 101 enters the optical direction conversion panel 54 from the incident surface (lower surface in the figure) and is refracted in a desired direction θ3 by the lens action of the linear Fresnel lens provided on the exit surface (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 substrate.

[0041] As a result, the nearly parallel light beam from the light guide can be given directionality in the desired direction. That is, the image light, which is the light from the liquid crystal display panel 52 that constitutes the information display device 48, is directed towards the transparent sheet 51 provided on the windshield 6, as described below, without being seen by the driver or passengers inside the vehicle. Originally, the image light was then reflected and diffused in one direction by the transparent sheet 51, and the reflected image was seen by the driver.

[0042] In other words, with this light direction conversion panel 54, the image light from the image display device 48 (see Figure 2 or Figure 3) is not directly visible from inside the vehicle, and therefore does not interfere with driving. Only the reflected image from the reflected light is monitored by the driver and passengers. Furthermore, by providing a light-absorbing paint or pigment on the joint surface 88 of the Fresnel lens, the generation of light other than the light beam traveling in the desired direction is suppressed. As a result, unwanted light is not mixed into the image light reflected by the windshield, so the imaging performance is not impaired.

[0043] <Protective cover> Figure 7 is a cross-sectional view showing the schematic configuration of a protective cover 50 provided on the upper surface of a light direction conversion panel 54, adjacent to the dashboard 47. A black stripe 59 is provided on a portion of the light-emitting side of the substantially transparent substrate 56. To reduce surface reflection of external light, including sunlight, the black stripe 59 should be made of a paint containing carbon black. In addition, an anti-reflective coating is provided on the parts without the black stripe to suppress surface reflection, thereby significantly reducing external light reflection on the surface of the protective cover 50 and reducing interference from external light reflection when the driver is operating the vehicle. On the other hand, to enhance the light-shielding performance against sunlight, the anti-reflective coating should have properties that reflect near-infrared and infrared light.

[0044] On the other hand, a film or membrane 50a that absorbs or reflects the P-wave component of the sunlight beam is deposited or adhered to the light-incident side of the substantially transparent substrate 56. As a result, since the P-wave component of sunlight does not incident on the image display device 48, the reliability regarding light resistance and heat resistance is greatly improved. At the same time, it also has the characteristics of a filter that selectively transmits the S-polarized image light output from the image display device 48, so the contrast performance of the resulting image is greatly improved.

[0045] Furthermore, since the image source constituting the above-mentioned image display device 48 is a liquid crystal display panel 52, if the driver is wearing polarized sunglasses, a problem occurs in which certain polarizations are blocked and the image cannot be seen. To prevent this, a wave plate 50b, such as a λ / 4 plate, λ / 8 plate, or λ / 16 plate, is placed between the film or membrane 50a and the substrate 56 of the protective cover 50 provided on the light output side of the image display device 48. By providing the wave plate 50b, the polarization direction of the light beam is aligned to a specific direction, and the image light is polarized at an optimal angle, thereby shifting the polarization axis by a desired amount from the polarization direction of the polarized sunglasses.

[0046] On the other hand, even with the same polarization, by rotating the absorption axis, for example, by shifting the absorption axis of the polarizing plate on the output side of the LCD panel by 30 degrees or more relative to the absorption axis of polarized sunglasses, the absorption can be reduced to about 50%, thus resolving the problem of the image being invisible.

[0047] Furthermore, when the polarization axis is rotated to approach circular polarization, the polarization axis of the image light from the information display device 48 rotates from S-polarization. As a result, the reflectivity of the front glass 6 decreases and the brightness of the image decreases, so it is best to choose a setting that balances both.

[0048] <Unidirectional transparent sheet> Next, the structure and function of the transparent sheet 51 will be explained with reference to Figure 8. Sunlight entering the windshield 6 (for the sake of explanation, it will be assumed to be horizontally positioned) from an oblique direction reflects its S-polarization and transmits its P-polarization towards the transparent sheet 51. The transparent sheet 51 is composed of a polarizing plate 57 that transmits S-waves, a transparent diffusion sheet material 55, and a phase difference plate 58. This transparent sheet 51 is made of a film stretched while dissolving a thermoplastic polymer in which nanoparticles of zirconium or diamond with a high refractive index are dispersed, for example, "Kaleidoscreen" manufactured by JXTG Energy Corporation (see Patent Document 3 mentioned above). When no image is displayed, it is transparent and does not obstruct the driver from monitoring the outside world (outside the vehicle). On the other hand, when an image is displayed, it diffuses and reflects the image light, thereby enabling a one-way display that allows the driver and passengers to see the image information. In this case, the degree of haze (HAZE), defined by the ratio of the diffuse transmittance to the parallel light transmittance of the transparent sheet 51, is practically acceptable if it is 10% or less, but preferably 4% or less. On the other hand, the haze of automotive windshields is 2% or less.

[0049] Since the image light from the image display device 48 is S-polarized, it has a high reflectivity when incident at an oblique angle, and is scattered inside the aforementioned transparent diffusion sheet material 55 before being emitted towards the observer. On the other hand, some of the image light has its polarization direction disturbed by scattering and diffusely passes through the transparent diffusion sheet 55 before being emitted towards the windshield 6. At the incident surface of the windshield 6, the refractive index difference is small, so the level of the double image generated by the reflected light is low. In contrast, the intensity of the reflected light generated at the emission surface (the surface in contact with the outside world) of the windshield 6 is mostly S-polarized, so the reflectivity is high. The image light reflected at this surface passes through the polarizer 57 again after reflection and is absorbed, so it does not return to the observer. As a result, the double image caused by the reflected image on the windshield 6 is eliminated, and the image quality is greatly improved. It goes without saying that the same effect can be obtained by similarly attaching the aforementioned transparent sheet 51 to the combiner instead of the windshield 6 as the reflective surface for the image.

[0050] As described above, the transparent sheet 51, as shown in Figure 8, absorbs the P-polarized sunlight component that has passed through the windshield under predetermined daytime conditions (and subsequently through the combiner in the combiner system) 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, thereby preventing it from returning to the liquid crystal display panel and polarizer.

[0051] <Vehicle Information Display System> As described in detail above, the vehicle information display system equipped with the vehicle information display device 100 includes a large, high-resolution video display device 48 located at the position of the dashboard 47 (see Figure 2) corresponding to the video display area in the lower end region of the windshield 6, which is a shield glass, as indicated by the arrow in Figure 3. By reflecting the displayed image off the windshield, the driver and passengers can directly monitor the reflected image.

[0052] Figure 9 shows an example of the arrangement of the vehicle information display device 100 of this embodiment, including the video display device 48 and transparent sheet 51 described above, in the cockpit of a car. Figure 9(a) shows a system corresponding to a car with the steering wheel on the left side, and Figure 9(b) shows a system corresponding to a car with the steering wheel on the right side. In the image display area of ​​the figure (corresponding to the area where the transparent sheet 51 is attached), the vehicle information display device 100 is used to reflect video information off the windshield 6, and the driver is allowed to monitor the reflected image. In this case, it is preferable to set the image display area to an area or region that does not interfere with the driver's monitoring of the scenery outside the car, such as the area where the hood of the vehicle shown by the dashed line in the figure is monitored.

[0053] As shown in the figure, the aforementioned vehicle information display device 100 is positioned inside the dashboard 47 between the windshield 6 and the steering wheel 43, with the image display device 48 facing the steering wheel 43, starting from the windshield 6. As a result, the vehicle information display device 100 reflects the image of the large, high-resolution image display device onto the windshield 6, which is the external view that the driver monitors through the windshield 6 when driving the vehicle. This provides a vehicle information display system that allows the driver and passengers to monitor the reflected image.

[0054] Furthermore, the rearview mirror 71 in Figure 9 is equipped with a camera 72 that monitors the driver's condition and the interior of the vehicle. For example, it would be possible to control the direction of the light emitted from the aforementioned information display device to match the driver's eye level.

[0055] Figure 10 is a schematic diagram showing an example of a system (Figure 10(b)) that, in addition to the vehicle information display device 100 described above, also provides video information to the passenger in the front passenger seat, and further includes a head-up display (HUD) device. Figure 10(a) shows a system corresponding to a car with the steering wheel 43 positioned on the left side, similar to Figure 9, while Figure 10(b) shows a system corresponding to a car with the steering wheel 43 positioned on the right side.

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

[0057] While a known, general-purpose device can be used as the HUD device 700, an example is outlined below.

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

[0059] The HUD device 700 includes an image display device 704 that projects image light to display information, and a corrective lens element 702 to correct distortions and aberrations that occur when the image displayed on the image display device 704 is formed as a virtual image by a concave (free-form) mirror 701. The image light beam from this information display device 700 is emitted from an aperture (not shown) toward the windshield 6.

[0060] Furthermore, the HUD device 700 also includes a video display device 704 and a control device 740 that controls its backlight. The optical components, including the video display device 704 and the backlight, form a virtual image optical system and include a concave mirror 701 that reflects light. The light reflected by this optical component is then reflected by the windshield 6, which is the projection target, and directed towards the driver's line of sight 8. The video display device 704 can be, for example, an LCD (Liquid Crystal Display) with a backlight, or a self-emissive VFD (Vacuum Fluorescent Display).

[0061] Furthermore, the illustrated control device 740, which constitutes the HUD device 700, acquires various information from the navigation system 761 as foreground information (i.e., information displayed in front of the vehicle as a virtual image), such as the speed limit and number of lanes of the road corresponding to the vehicle's current location, and the planned route of the vehicle set in the navigation system 761. The driver assistance ECU 762 is a control device that realizes driver assistance control by controlling the drive system and control system according to obstacles detected as a result of monitoring by the surrounding monitoring device 763. Such driver assistance control includes well-known technologies such as cruise control, adaptive cruise control, pre-collision safety, and lane keeping assist. The surrounding monitoring device 763 shown in Figure 11 is a device that monitors the situation around the vehicle. Examples include a camera that detects objects present around the vehicle based on images taken of the area around the vehicle, and a search device that detects objects present around the vehicle based on the results of transmitting and receiving search waves.

[0062] The control device 740 of the HUD device 700 described above acquires information from the driver assistance ECU 762 (for example, the distance to the preceding vehicle, the direction of the preceding vehicle, the location of obstacles and signs, etc.) as foreground information. Furthermore, the control device 740 receives an ignition (IG) signal and vehicle status information. Of this information, vehicle status information is information acquired as vehicle information and does not require high-resolution display, such as the remaining fuel level of the internal combustion engine and the temperature of the coolant, and includes warning information that indicates a predetermined abnormal state. It also includes the result of turn signal operation, the vehicle's driving speed, and even shift position information. The control device 740 described above is activated when an ignition signal is input. The projection target can be any member onto which information is projected, and is not limited to the windshield 6; it can also be a combiner, as long as it forms a virtual image in front of the vehicle in the driver's line of sight 8 and is visible to the driver.

[0063] <Vehicle Information Display System Modification: External Display> According to the embodiment described in detail above, when a driver is driving their vehicle, necessary video information can be displayed in one direction and in high resolution to the driver and passengers inside the vehicle via the windshield 6, which is a projection member that is a shield glass constituting the vehicle, allowing them to monitor the information. However, in this case, it is not possible to monitor the information from outside the vehicle. However, the vehicle information display system according to one embodiment of the present invention is not limited to the embodiment described above, and it is also possible to display video information to the outside of the vehicle. That is, not only the windshield 6 described above, but also the rear glass 6' and side glass 6'' which are shield glass can be used to display video information to the inside or outside of the vehicle in the same manner.

[0064] For example, in the vehicle information display system of this embodiment, information indicating the status of the vehicle, such as "vacant," can be displayed on a part of the taxi's windshield 6, and also on the rear window 6' and side windows 6''. In addition, other information such as publicity and advertising can be displayed to the outside of the vehicle. Furthermore, in vehicles such as buses and trains, information such as the route and destination can be displayed in one direction to the outside of the vehicle on the windshield, rear window, or side windows. The configuration of the vehicle information display device 100'' when information is displayed to the outside will be described below.

[0065] Figure 12 shows a system that displays and monitors necessary video information in high resolution in one direction to the outside of the vehicle via the windshield 6, which is the projection target. More specifically, this example shows the status of a taxi ("vacant," etc.) displayed on the windshield of a taxi. In this modified example, in the configuration shown in Figure 2, a transparent sheet 51' is provided on the surface of the windshield 6 to diffuse and transmit video light from the video display device 48 through the windshield 6, and the image is transmitted to the outside of the vehicle as shown by the arrow in the figure, so that, for example, pedestrians can monitor it. As a result, the driver and passengers can display necessary information on the windshield 6 to the outside of the vehicle, but this display does not interfere with monitoring the scenery outside the vehicle from inside the vehicle, and does not interfere with the driver's driving.

[0066] The transparent sheet 51', like the transparent sheet 51, is composed of a polarizing plate 57 that transmits S waves and a transparent diffusion sheet material 55. In this case, a film made by dissolving and stretching a thermoplastic polymer in which nanoparticles of zirconium or diamond with a high refractive index are dispersed, such as JXTG Energy's "Kaleidoscreen" (see Patent Document 2 mentioned above), is used. This makes it transparent when no image is displayed, while diffusing and transmitting the image light when an image is displayed. This makes it possible to achieve a one-way display that shows information only to the outside without allowing the driver or passengers to see the image information or interfere with monitoring the scenery outside the vehicle.

[0067] Figure 13 shows the effect 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 phase difference plate 58. Similar to the transparent sheet 51, it reduces the intensity of sunlight by reflecting its S-polarization and transmitting its P-polarization when sunlight is incident from an oblique direction. At this time, the phase difference plate 58 rotates the polarization axis of the P-polarization, causing some of the sunlight to be absorbed by the polarizing plate 57. As a result, the damage that the image display device 48 receives from sunlight can be dispersed.

[0068] On the other hand, the image light diffused outside the vehicle by the action of the transparent diffusion sheet material 55 is reflected by the rear glass 6' and returns to the interior of the vehicle. This light obstructs the driver's view and is therefore a hindrance to driving. In this embodiment, a phase difference plate 58 is placed between the rear glass 6' and the polarizing plate 57, and the reflected light is absorbed by the polarizing plate, so that the information from the image light is displayed in one direction, toward the outside of the vehicle, without being visible to the driver or passengers inside the vehicle. At that time, the information from the image light does not interfere with driving by preventing the driver or passengers inside the vehicle from monitoring the scenery outside the vehicle. The degree of haze (HAZE), defined by the ratio of the diffuse transmittance and the parallel light transmittance of the transparent sheet 51' described above, is practically acceptable if it is 10% or less, but preferably it should be 4% or less. On the other hand, the haze of automotive windshields is 2% or less.

[0069] As mentioned above, displaying information to the outside of a vehicle using the windshield 6, and even parts of the shield glass such as the rear window 6' and side windows 6'', would be suitable for displaying information such as "vacant" indicating the vacancy status of a taxi to pedestrians on the road. Furthermore, as mentioned above, the vehicle information display device according to one embodiment of the present invention not only displays video information in one direction on the windshield 6, but also, for example, in large vehicles such as buses and trains, it is possible to display various types of information, including advertisements, notices, etc., using the projection members such as the rear window 6' and side windows 6'' (see Figure 1), which are shield glass components of the vehicle. The configuration and operation of the vehicle information display system when displaying information to the outside of a vehicle will be described below.

[0070] Figure 14 shows another modification in which, as a projected element that constitutes part of the vehicle, information is displayed to, for example, pedestrians outside the vehicle via the rear window 6' that constitutes the vehicle 1. As a result, the driver and passengers can monitor the necessary information on the windshield 6 (see Figure 9), but at the same time, information can also be displayed outside the vehicle via the rear window 6'. However, the driver and passengers cannot monitor the information displayed to the outside, and therefore it does not obstruct the driver's field of view. In other words, the display of information to the outside does not interfere with the driver and passengers inside the vehicle monitoring the external scenery.

[0071] In this example, as shown in Figures 14(a) and 14(b), an image display device 48 is placed below the rear glass 6', which is a projection target member that constitutes part of the vehicle, and image information is displayed by projecting the image light from the device toward an image display area set on the entire surface or part of the rear glass 6'.

[0072] In this example, it is natural that the transparent sheet 51' shown in Figure 13 above is provided in the image display area of ​​the rear window 6'. In addition, the projected member that displays video information in one direction toward the outside of the vehicle is not limited to the windshield 6 or rear window 6' described above, but can also be used, for example, the side window 6" (see Figure 1) that makes up the side of the vehicle. In that case, although not shown here, it is natural that the video display device 48 is placed on a member near the side window 6" (for example, the adjacent ceiling surface or part of the window frame), and the transparent sheet 51' shown in Figure 13 is provided in the image display area of ​​the side window 6". Displaying information on such a side window 6" would be suitable, for example, for displaying messages such as "Sorry to keep you waiting" or "Please get in" to passengers on the street in a taxi.

[0073] In addition, the examples described above describe vehicle information display devices 100, 100', and 100'' that display video information in one direction, either outside or inside the vehicle, via the windshield 6, rear window 6', and side window 6'' which are projection members constituting the vehicle. However, the present invention is not limited to these, and it is also possible to appropriately combine, for example, 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. As a result, for example, when applied to public transportation such as buses and trains, it is possible to display various types of information, including advertisements, notices, etc., to the public outside the vehicle via the rear window 6' or side window 6'' (however, it is not visible from inside the vehicle), thereby enabling the effective display of information to the public.

[0074] Although various embodiments have been described in detail above, the present invention is not limited to the embodiments described above, but includes various modifications. For example, the embodiments described above are detailed explanations of the entire system in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of Symbols]

[0075] 1...Automobile (vehicle) body, 6...Windshield, 6'...Rear window, 6"...Side window, 100...Vehicle information display device, 101...Light source device, 48...Image display device (image projection device), 50...Protective cover, 50a...Membrane or film, 50b...Waveplate, 51...Transparent sheet (film), 52...Liquid crystal display panel (image display element), 54...Light direction conversion panel, 55...Transparent diffusion sheet material, 56...Substrate, 57...Polarizing plate, 58...Phase difference plate, 59...Black stripe, 300...Smartphone.

Claims

1. A display device installed in a vehicle, Display panel and The display panel is positioned between the vehicle's shield glass and includes a polarizing plate that absorbs specific polarizations, The light beam travels from the display panel toward the display area of ​​the vehicle's shield glass. The direction of the light beam from the horizontally installed display panel is inclined away from the driver of the vehicle, with reference to the normal of the display surface of the display panel. The display area of ​​the shield glass is located near the lower end of the shield glass. It is equipped with a second display panel different from the aforementioned display panel, A light beam propagates from the second display panel toward the second display area of ​​the shield glass. The second display area of ​​the shield glass is located near the lower end of the shield glass and is at a different position from the display area in the left-right direction as viewed from the driver of the vehicle. Display device.

2. In the display device according to claim 1, A protective cover is provided for the aforementioned display panel. Display device.

3. In the display device according to claim 2, The protective cover has a film or membrane that absorbs or reflects polarized wave components from outside the vehicle. Display device.

4. In the display device according to claim 1, A phase difference plate is provided on the output side of the display panel. Display device.

5. In the display device according to claim 1, A linear Fresnel lens is positioned between the display panel and the shielding glass. Display device.

6. In the display device according to claim 5, The linear Fresnel lens has light-absorbing surfaces arranged periodically. Display device.

7. In the display device according to claim 1, The video light from the aforementioned display panel is not directly visible to the driver of the vehicle. Display device.

8. In the display device according to claim 1, The resolution of the aforementioned display panel is 1280 x 720 pixels or higher. Display device.

9. In the display device according to claim 1, Furthermore, it is equipped with a head-up display, The display area of ​​the head-up display as seen by the driver of the vehicle is located in a different position from the display area of ​​the shield glass. Display device.

10. In the display device according to claim 1, Furthermore, it is equipped with a head-up display, The display area of ​​the head-up display as seen by the driver of the vehicle is located in a position different from both the display area of ​​the shield glass and the second display area of ​​the shield glass. Display device.

Images