Display device

Abstract

To provide a display device which can display high-resolution video information toward a driver of a vehicle.SOLUTION: A display device comprises: a display panel which emits video light; and a polarizing plate which absorbs a specific polarized wave included in the video light emitted from the display panel. The display device displays a video generated on the display panel toward a driver of the vehicle by reflecting the video light that is emitted from the display panel and whose specific polarized wave is absorbed by a shield glass of the vehicle.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

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

[0003] In this type of information display device, generally, the image displayed on the image display device is projected onto the driver's viewpoint using an optical system that includes a concave mirror (acting like a convex lens) so that the image information can be monitored as a virtual image with the aim of reducing the movement of the driver's viewpoint.

[0004] Although different from this type of information display device, a transparent screen or a reflective screen having a light diffusion layer containing a binder or fine particles is generally used as a screen in an image display device having a screen, and is already known from the following Patent Documents 2 and 3. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-194707 A [Patent Document 2] Patent No. 6133522 [Patent Document 3] Patent No. 6199530 Summary of the Invention [Problem to be solved by the invention]

[0006] In the vehicle information display device of the head-up display type, which is the conventional technology described above, 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, when displaying information such as a map, the displayed map information may obstruct the view of the outside. In addition, in such a vehicle information display device, it is desired to expand the displayable area, while it is also required that the virtual image has high resolution and high visibility. For this reason, a liquid crystal display element (liquid crystal display panel) is often used because high-quality images can be easily obtained and are inexpensive. On the other hand, a small liquid crystal display element is used to reduce the size of the set, and therefore the resolution of the obtained projection image is insufficient, and a new problem has become clear that it is not suitable for displaying high-resolution images displayed on a smartphone, for example.

[0007] In addition, such a head-up display type vehicle information display device is not intended to display image information to the outside of the vehicle. Therefore, when it is desired to display image information to the outside of the vehicle, an image display device such as a display is installed inside the vehicle and the image information is displayed through the glass of the vehicle. However, in such a case, these image display devices obstruct the driver's field of vision, which is not desirable from the viewpoint of safe driving.

[0008] Incidentally, Patent Documents 2 and 3, which are prior art, disclose a reflective screen or a transparent screen having a light diffusion layer containing a binder or fine particles, which is used in information display devices, but do not teach anything about the application of the screen to vehicles to which the present invention pertains, or about specific methods, forms, or configurations therefor.

[0009] The present invention aims to provide a vehicle information display device capable of displaying high-resolution video information through the windshield (and further the rear and side windows) which is the shield glass of the vehicle, in place of the conventional head-up display type vehicle information display device, in which the displayed video information is visible to passengers (including the driver) inside the vehicle but not from outside the vehicle, or is visible from outside the vehicle but not from passengers (including the driver) inside the vehicle, i.e., a so-called unidirectional display.Furthermore, the present invention aims to provide an information display system for a vehicle that utilizes such a vehicle information display device. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the present invention provides The present invention provides a display device comprising a display panel that emits image light, and a polarizing plate that absorbs a specific polarized wave contained in the image light emitted from the display panel, and which reflects the image light emitted from the display panel and from which the specific polarized wave has been absorbed by a shield glass of a vehicle, thereby displaying an image generated by the display panel as a virtual image to a driver of the vehicle. Effect 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 further, a new and highly usable information display system for a vehicle is provided that utilizes such a vehicle information display device. [Brief description of the drawings]

[0012] [Figure 1] 1A and 1B are top views of an automobile equipped with a vehicular information display system according to an embodiment of the present invention, and diagrams illustrating differences in the radius of curvature of the windshield. [Diagram 2] 1 is a diagram showing a schematic configuration of a vehicle information display device constituting a vehicle information display system according to an embodiment of the present invention; [Diagram 3]FIG. 2 is a diagram illustrating a more specific configuration of the vehicle information display device. [Figure 4] 2 is a diagram showing a detailed configuration of a light source device of a video projection device constituting the vehicle information display device. FIG. [Diagram 5] FIG. 2 is a diagram showing an example of an optical system of a light source device constituting a video projection device. [Figure 6] 1 is a diagram for explaining the principle of a light direction conversion panel constituting a vehicle information display device. FIG. [Figure 7] 2 is a cross-sectional view showing a schematic configuration of a protective cover that constitutes the vehicle information display device. FIG. [Figure 8] 1A to 1C are diagrams illustrating the configuration and function of a unidirectional transparent sheet that constitutes a vehicle information display device. [Figure 9] FIG. 1 is a diagram showing an example of the arrangement of a vehicle information display device in a cockpit of an automobile. [Figure 10] FIG. 1 is a diagram showing an example of the arrangement of a vehicle information display device in a cockpit of an automobile. [Figure 11] 1 is a diagram showing a schematic configuration of a HUD type information display device constituting a vehicle information display system according to an embodiment of the present invention. [Figure 12] 10A and 10B are diagrams illustrating a modified example of the vehicular information display system. [Figure 13] 13A to 13C are diagrams illustrating the effect of a transparent sheet in the modified example of the information display system for a vehicle. [Figure 14] 13A and 13B are diagrams illustrating another modified example of the vehicular information display system. [Figure 15] 1 is a schematic diagram for explaining the change in reflectance of glass depending on the angle of incidence of S-polarized light and P-polarized light. FIG. [Figure 16] FIG. 1 is a diagram showing the spectral irradiance of sunlight. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note 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 ideas disclosed in this specification. In addition, in all the drawings for explaining the present invention, the same reference numerals are given to parts having the same functions, and repeated explanations 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 it is mounted on an automobile, train, airplane, or the like, particularly on an automobile. In front of the driver's seat of an automobile body 1, there are a windshield 6, a rear glass 6', a side glass 6" and the like (collectively referred to as "shield glass"), which are translucent projection members onto which image light is projected and displayed. In particular, the inclination angle of the windshield 6 with respect to the vehicle body differs depending on the type of automobile. The inventors also investigated the radius of curvature of the windshield 6 in order to realize an optimal virtual image optical system. As a result, it was found that the radius of curvature Rh of the windshield 6 in the horizontal direction parallel to the ground surface of the automobile, which is parallel to the ground surface of the automobile, differs from the radius of curvature Rv in the direction perpendicular to the horizontal axis, and that the following relationship generally holds between Rh and Rv, as shown in FIG. 1(b). Rh>Rv It was also found that the difference in the radius of curvature, that is, Rh relative to Rv, was 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 inside the vehicle to monitor video information through a windshield 6, a rear window 6', and / or a side window 6" as projection members that constitute part of the vehicle when the driver is driving the vehicle, and that also displays the video information to the outside of the vehicle. As a result, the driver and passengers can monitor necessary information from inside the vehicle by appropriately displaying it in a display area such as the windshield 6, but cannot monitor the information from outside the vehicle. Alternatively, video information can be displayed to the outside of the vehicle through the rear window 6' or side window 6" (which may include the windshield 6), and this displayed information can be monitored from outside but cannot be monitored from inside the vehicle, so it does not prevent the driver or passengers from monitoring the outside scenery and does not interfere with driving.

[0016] Moreover, 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 light has two different polarization directions (hereinafter referred to as S-polarized light and P-polarized light), namely, light with a vibration direction perpendicular to the light's traveling direction and light with a horizontal vibration direction, mixed together. In particular, in areas where the angle of incidence on the windshield 6 exceeds 50 degrees, as shown in Fig. 15, the reflectance on the glass surface differs depending on the S-polarized light, P-polarized light, and further depending on the angle of incidence.

[0017] Therefore, in this embodiment, based on the findings of the inventors described above, i.e., taking into consideration that most of the sunlight entering through the windshield 6 is a P-polarized component, it has been confirmed that reducing the P-wave component is particularly effective in suppressing external light, including sunlight, from entering the information display device, and in addition, it is effective to use the S-wave component as the image light projected from the information display device.

[0018] Next, with reference to FIG. 2, a specific configuration of the vehicle information display device constituting the vehicle information display system according to the present invention will be described in detail below with reference to the drawing.

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

[0020] In the vehicle information display device 100, the image display device 48, as shown in FIG. 2, projects high-resolution map information (image on a large, high-resolution image 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 described in detail below, and displays the image on the windshield 6 by reflecting the information toward the eye 8 of the observer (driver) by a transparent sheet (film) 51 provided on the surface of the windshield 6.

[0021] In this example, an example of using a smartphone 300, which is a high-performance mobile terminal device equipped with a navigation function that provides map information, etc., is shown, and 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) and the image can be displayed, thereby allowing the driver to monitor high-resolution image information using the vehicle information display device 100.

[0022] Although not shown here, like the image display device 48, the smartphone 300 is equipped with a control unit composed of a CPU (Central Processing Unit) and various solid-state memories such as RAM and ROM having the functions of working memory and information accumulation / storage means, and it goes without saying that it has the function of generating the necessary images and displaying them 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 (image display element) 52 constituting the image display device 48 is, for example, a relatively large liquid crystal display panel with a screen size of more than 6 inches. In general, the radius of curvature of the windshield 6 often differs partially, so that uneven (vertical and horizontal) distortion occurs in the displayed image depending on the location where the image is reflected. For this reason, distortion correction is required to obtain a correct image when the reflected image is viewed from the monitoring direction. To perform this distortion correction at a level that does not cause practical problems, the panel resolution needs to be 1280 x 720 dots or more.

[0024] In addition, image display device 48 is equipped with light source device 101 that constitutes its light source, together with liquid crystal display panel 52 described above. In FIG. 3, light source device 101 is shown below liquid crystal display panel 52 as an exploded perspective view.

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

[0026] 3, the vehicle information display device 100 is configured to include a liquid crystal display panel 52 constituting the image display device 48, a light direction conversion panel 54 for controlling the directional characteristics of the emitted light beam 30 from the light source device 101, and a narrow-angle diffusion plate as necessary. That is, polarizing plates are provided on both sides of the liquid crystal display panel 52, and image light of a specific polarization is modulated in intensity by an image signal and output. As a result, a high-resolution image (image of a large-scale high-resolution image display device) from a smartphone 300 or the like is projected toward the windshield 6 through the light direction conversion panel 54, and is reflected toward the eye 8 of the observer (driver) through a transparent sheet 51 provided on the surface of the panel.

[0027] As shown in Fig. 4, the light source device 101 is made of, for example, plastic and is configured with a case for the light source device 101 (see Fig. 3) that houses LED elements, a collimator, a composite diffusion block, a light guide, and the like, which will be described later in detail, and a liquid crystal display panel 52 that constitutes the image display device 48 is attached to the upper surface of the case. LED (Light Emitting Diode) elements 14a and 14b, which are semiconductor light sources, and an LED board 102 on which a control circuit for the LED elements are mounted are attached to one side of the case for the light source device 101, and a heat sink 103, which is a member for cooling heat generated by the LED elements and the control circuit, is attached to the outer side of the LED board 102 (see Fig. 3).

[0028] On the other hand, the image 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 further an FPC (Flexible Printed Circuits) 403 (see FIG. 3) electrically connected to the liquid crystal display panel 52. That is, 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 a control signal from a control circuit (not shown here) constituting an electronic device together with the LED elements 14a and 14b, which are solid-state light sources, as will be described in detail later.

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

[0030] 4 and 5 show a plurality of (two in this example) LED elements 14a and 14b constituting the light source, which are attached at predetermined positions relative to the LED collimator 15. Each of the LED collimators 15 is formed of a light-transmitting resin such as acrylic. As shown in FIG. 5(b), the LED collimator 15 has a cone-shaped outer peripheral surface 156 obtained by rotating a parabolic cross section, and a concave portion 153 having a convex portion (i.e., a convex lens surface) 157 formed at the center at the top of the LED collimator 15. The center of the flat surface of the LED collimator 15 has a convex lens surface 154 protruding outward (or a concave lens surface recessed inward). The parabolic surface 156 forming the cone-shaped 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 therein, or a reflective surface is formed thereon.

[0031] On the other hand, the LED elements 14a and 14b are arranged at predetermined positions on the surface of the circuit board, that is, the so-called LED substrate 102. The LED substrate 102 is arranged and fixed to the LED collimator 15 such that the LED element 14a or the LED element 14b on the surface is located at the center of the recess 153.

[0032] According to this configuration, the light emitted from the LED element 14a or the LED element 14b by the above-mentioned LED collimator 15, particularly the light emitted from the central part toward the upper side (to the right in the figure), is collected and made parallel by the two convex lens surfaces 157, 154 that form the outer shape of the LED collimator 15. The light emitted from the other parts toward the periphery is reflected by the parabolic surface that forms the conical outer circumferential surface of the LED collimator 15, and is similarly collected and made parallel. In other words, the LED collimator 15 that has a convex lens in its center and a parabolic surface formed on its periphery makes it possible to extract almost all of the light generated by the LED element 14a or the LED element 14b as parallel light, and it becomes possible to improve the utilization efficiency of the generated light.

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

[0034] 5(a) is provided on the exit surface of the polarization conversion element 21. That is, the light emitted from the LED element 14a or the LED element 14b is collimated by the action of the LED collimator 15, enters the synthesizing diffusion block 16, is diffused by the texture 161 on the exit side, and then reaches the light guide 17 described below.

[0035] The light guide 17 is a rod-shaped member made of a translucent resin such as acrylic and having a cross section of approximately a triangle (see Figure 5(b)), and, as is clear from Figures 4 and 5, is provided with a light guide light incident portion (light guide light incident surface) 171 that faces the exit surface of the synthetic diffusion block 16 via a first diffuser 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 diffuser plate 18b.

[0036] 4, a number of reflective surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape in the light guide light reflecting portion 172 of the light guide 17. The reflective surfaces 172a (line segments slanting upward to the right in the figure) form an angle αn (n: natural number, for example, 1 to 130 in this example) with the horizontal plane indicated by the dashed line in the figure. As an example, αn is set to 43 degrees or less (but 0 degrees or more) here.

[0037] Light guide light incident portion 171 is formed in a curved convex shape inclined toward the light source side. Accordingly, the parallel light from the exit surface of synthetic diffusion block 16 is diffused via first diffusion plate 18a and enters light guide 17, and as is clear from Fig. 4, the parallel light is bent (deflected) slightly upward by light guide light incident portion 171 and reaches light guide light reflecting portion 172, where it is reflected and reaches liquid crystal display panel 52 provided on the exit surface at the top of the figure.

[0038] As described above in detail, the image display device 48 of the vehicle information display device 100 described above can improve the light utilization efficiency and the uniform illumination characteristics, and can be manufactured compactly and at low cost, including the modularized S-polarized light source device. Note that in the above description, the polarization conversion element 21 is described as being attached after the LED collimator 15, but the present embodiment is not limited to this, and it will be clear to those skilled in the art that the same action and effect can be obtained by providing it in the optical path leading to the liquid crystal display panel.

[0039] In addition, in the light guide light reflection section 172, a large number of reflection surfaces 172a and connection surfaces 172b are alternately formed in a sawtooth shape, and the illumination light beam is totally reflected on each reflection surface 172a and directed upward, and furthermore, a narrow-angle diffusion plate is provided in the light guide light emission section 173 so that the illumination light beam enters the light direction conversion panel 54, which controls the directional characteristics as a substantially parallel diffused light beam, and then enters 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 light emission surface 173 and the liquid crystal display panel 52, but it goes without saying that the same effect can be obtained by providing the light direction conversion panel 54 on the emission surface of the liquid crystal display panel 52.

[0040] <Light redirection panel> 6 is a schematic diagram for explaining the principle of the light direction conversion panel 54, which constitutes 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-mentioned image display device 48. The light beam from the light guide 17 of the above-mentioned light source device 101 enters the light direction conversion panel 54 from the entrance surface (the 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 (the upper surface in the figure). At this time, the desired direction θ3 is uniquely derived from Snell's law by 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, it is possible to provide directivity in a desired direction to the substantially parallel light beam from the light guide. That is, the image light, which is 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, but travels toward a transparent sheet 51 provided on the windshield 6, which will be described below. After that, the image light is normally reflected and diffused in one direction by the transparent sheet 51, and the reflected image is visually recognized by the driver.

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

[0043] <Protective cover> FIG. 7 is a cross-sectional view showing a schematic configuration of the 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, and in order to reduce the surface reflection of external light including sunlight, the black stripe 59 may be made of a paint containing carbon black as a black paint. In addition, in the part where the black stripe is not provided, an anti-reflection film is provided to suppress surface reflection, so that the reflection of external light on the surface of the protective cover 50 is significantly reduced, and the hindrance caused by the reflection of external light when the driver drives the vehicle is reduced. On the other hand, in order to enhance the light-shielding performance against sunlight, it is preferable to give the anti-reflection film the property of reflecting near-infrared light and infrared light.

[0044] On the other hand, a film 50a that absorbs or reflects the P wave component of the solar light flux is formed or adhered to the light incident side of the substantially transparent base material 56. As a result, the P wave component of the solar light does not enter the image display device 48, so reliability in terms of light resistance and heat resistance is greatly improved. On the other hand, since it also has the properties of a filter that selectively transmits the S polarized image light output from the image display device 48, the contrast performance of the obtained image is greatly improved.

[0045] Since the image source constituting the above-mentioned image display device 48 is the liquid crystal display panel 52, when the driver wears polarized sunglasses, a problem occurs in which a specific polarized wave is 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 arranged between the membrane or film 50a and the substrate 56 in 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 in a specific direction, and the image light is set to an optimal polarization angle, and the polarization axis is shifted 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 exit side of the liquid crystal panel by 30 degrees or more relative to the absorption axis of polarized sunglasses, absorption will be about 50%, eliminating the problem of the image not being visible.

[0047] In addition, 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-polarized light. This reduces the reflectance of the windshield 6 and reduces the brightness of the image, so it is best to select a balance between the two.

[0048] <Unidirectional transparent sheet> Next, the configuration and function of the transparent sheet 51 will be described with reference to FIG. 8. When sunlight is incident on the windshield 6 (which is assumed to be horizontally disposed for convenience of explanation) from an oblique direction, its S-polarized waves are reflected and its P-polarized waves are transmitted toward 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 retardation plate 58. This transparent sheet 51 is made of a film that is stretched while melting a thermoplastic polymer in which nanoparticle zirconium or nanoparticle diamond having a large refractive index is dispersed, for example, "Kaleidoscreen" manufactured by JXTG Energy Corporation (see Patent Document 3 mentioned above), and is transparent when no image is displayed, and does not hinder the driver from monitoring the scenery of the outside world (outside the vehicle), while on the other hand, when an image is displayed, the image light is diffused and reflected, thereby making it possible to realize a unidirectional display that allows the driver and passengers to visually recognize the image information. At this time, the haze (HAZE) defined by the ratio of the diffuse transmittance and parallel light transmittance of the transparent sheet 51 is 10% or less without any practical problems, but is preferably 4% or less. On the other hand, the haze of an automobile window glass is 2% or less.

[0049] The image light from the image display device 48 is S-polarized and has a high reflectance when it is obliquely incident, and is scattered inside the transparent diffusion sheet material 55 described above and emitted toward the observer. On the other hand, part of the image light has its polarization direction disturbed by scattering, and is diffused and transmitted through the transparent diffusion sheet 55 and emitted toward the windshield 6. Since the refractive index difference is small at the entrance surface of the windshield 6, the level of double images caused by reflected light is low. In contrast, the intensity of the reflected light generated at the exit surface (surface in contact with the outside world) of the windshield 6 is mostly S-polarized components, so the reflectance is high. The image light reflected at this surface passes through the polarizing plate 57 again after reflection and is absorbed, so it does not return to the observer. Therefore, double images caused by the reflected image on the windshield 6 do not occur, and the image quality is greatly improved. It goes without saying that the same effect can be obtained by attaching the transparent sheet 51 described above to the combiner instead of the windshield 6 as the image reflection surface.

[0050] As shown in FIG. 8, the transparent sheet 51 described above makes it possible to prevent the P-polarized sunlight components that pass through the windshield under specified daytime conditions (and then pass through the combiner in the case of the combiner method) from returning to the liquid crystal display panel and polarizing plate by absorbing them in front of the vehicle information display device 100 and the light direction conversion panel 54 and protective cover 50 provided on its upper surface.

[0051] <Vehicle information display system> According to the vehicle information display system equipped with the vehicle information display device 100 described above in detail, a large, high-resolution image display device 48 is provided at a position on the dashboard 47 (see FIG. 2) that corresponds to the image display area in the lower end area of ​​the windshield 6, which is a shield glass, as shown by the arrow in FIG. 3, and the displayed image is reflected by the windshield, allowing the driver and passengers to directly monitor the reflected image.

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

[0053] As shown in the figure, the above-mentioned vehicle information display device 100 is disposed inside the dashboard 47 between the windshield 6 and the steering wheel 43, in the order of the windshield 6 to the image display device 48, facing the steering wheel 43. As a result, it is possible to provide a vehicle information display system in which the vehicle information display device 100 reflects an image from a large, high-resolution image display device on the windshield 6, which is the external scenery that the driver monitors through the windshield 6 when driving the vehicle, i.e., a portion of the windshield 6, so that the driver and passengers can monitor the reflected image.

[0054] It should be noted that the rearview mirror 71 in FIG. 9 may be provided with a camera 72 for monitoring the driver's condition and the interior of the vehicle, and it may be possible to control the emission direction of the image light from the information display device described above to match the driver's eye height, for example.

[0055] Fig. 10 is a schematic diagram showing an example of a system (Fig. 10(b)) equipped with a head-up display (HUD) device in addition to the above-mentioned vehicle information display device 100. Fig. 10(a) shows a system corresponding to a car in which the steering wheel 43 is located on the left side, as in Fig. 9, and Fig. 10(b) shows a system corresponding to a car in which the steering wheel 43 is located on the right side.

[0056] Fig. 10(a) shows an example in which, in addition to the above-mentioned vehicle information display device 100 on the driver's seat side, a second vehicle information display device 100' is also mounted on the passenger's seat side, and in addition to an image display area (1) that the driver can monitor, an image display area (2) that the passenger can monitor is set in a part of the windshield 6 (right side of the figure). In addition, Fig. 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 mounted, and an image display area (2) is set for the passenger, and a HUD display area by the HUD device 700 is set for the driver in addition to the image display area (1) by the information display device 48.

[0057] It should be noted that a known general device can be adopted as the HUD device 700, but here, an outline of the device will be described below as an example.

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

[0059] The HUD device 700 includes an image display device 704 that projects image light that displays information, and a corrective lens element 702 for correcting distortion and aberration that occurs when a virtual image is formed from the image displayed on the image display device 704 using a concave (free-form surface) mirror 701. The image light flux from this information display device 700 is emitted toward the windshield 6 from an opening (not shown).

[0060] The HUD device 700 further includes a control device 740 that controls the image display device 704 and its backlight. The image display device 704 and optical components including the backlight are a virtual image optical system, and include a concave mirror 701 that reflects light. The light reflected by this optical component is reflected by the windshield 6, which is the projected member, and heads toward the driver's line of sight 8. Examples of the image display device 704 include a liquid crystal display (LCD) having a backlight, as well as a self-luminous vacuum flourescent display (VFD).

[0061] The illustrated control device 740 constituting the HUD device 700 obtains various information from the navigation system 761, such as the speed limit and number of lanes of the road corresponding to the current position on which the vehicle is traveling, and the planned route of the vehicle set in the navigation system 761, as foreground information (i.e., information to be displayed in front of the vehicle by a virtual image). The driving assistance ECU 762 is a control device for realizing driving assistance control by controlling the drive system and the control system according to an obstacle detected as a result of monitoring by the surroundings monitoring device 763. Examples of such driving assistance control include well-known technologies such as cruise control, adaptive cruise control, pre-crash safety, and lane keeping assist. The surroundings monitoring device 763 shown in FIG. 11 is a device that monitors the situation around the vehicle, and examples thereof include a camera that detects objects present around the vehicle based on an image captured around the vehicle, and a detection device that detects objects present around the vehicle based on the results of transmitting and receiving detection waves.

[0062] The control device 740 of the HUD device 700 described above acquires information from the driving assistance ECU 762 (for example, the distance to the preceding vehicle, the direction of the preceding vehicle, the position of obstacles and signs, etc.) as foreground information. Furthermore, an ignition (IG) signal and vehicle status information are input to the control device 740. Among these pieces of information, the vehicle status information is information acquired as vehicle information, and includes warning information indicating a predefined abnormal state, such as the remaining amount of fuel in the internal combustion engine and the temperature of the cooling water, which does not require high-resolution display. In addition, the information includes the operation result of the turn signal, the running speed of the vehicle, and even the shift position information. 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 may be not only the windshield 6 but also a combiner, and may be any member that forms a virtual image in front of the vehicle in the driver's line of sight 8 and allows the driver to visually recognize it.

[0063] <Modification of Vehicle Information Display System: External Display> According to the embodiment described above in detail, when the driver is driving his / her own vehicle, the necessary video information can be displayed in one direction at high resolution to the driver and / or passengers inside the vehicle for monitoring through the windshield 6 as a projection member which is a shield glass constituting the vehicle. Note that, at this time, the information cannot be monitored from outside the vehicle. However, the vehicular information display system according to one embodiment of the present invention is not limited to the above-described embodiment, and it is also possible to display other video information to the outside of the vehicle. That is, it is possible to display video information to the inside or outside of the vehicle in the same manner not only through the windshield 6 described above, but also through the rear glass 6' and / or side glass 6", which are shield glass.

[0064] For example, in the vehicle information display system of this embodiment, information indicating the vehicle status, such as "vacant", can be displayed on part of the windshield 6 of a taxi, and even on the rear windshield 6' or side windshield 6", or other information such as publicity and advertisements can be displayed to the outside of the vehicle. Also, in vehicles such as buses and trains, information such as routes and destinations can be displayed in one direction, facing outside the vehicle, on the windshield, rear windshield, or side windshield. The configuration of vehicle information display device 100" when displaying information to the outside is described below.

[0065] FIG. 12 shows a system for displaying necessary image information in one direction with high resolution to the outside of the vehicle through the windshield 6 as a projection member, and more specifically, an example of displaying the taxi status (such as "vacant") on the windshield of a taxi. In this modification, in the configuration shown in FIG. 2, a transparent sheet 51' is provided on the surface of the windshield 6, which diffuses and transmits the image light from the image display device 48 through the windshield 6, and the image is transmitted and displayed outside 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 the 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' is composed of a polarizing plate 57 that transmits S-waves and a transparent diffusion sheet material 55, similar to the transparent sheet 51. In this case, a film made by melting and stretching a thermoplastic polymer in which nanoparticle zirconium or nanoparticle diamond with a large refractive index is dispersed, for example, "Kaleidoscreen" manufactured by JXTG Energy Corporation, is used (see Patent Document 2 mentioned above), which is transparent when no image is displayed, and diffuses and transmits image light when an image is displayed. This makes it possible to realize a one-way display that can display information only to the outside without preventing the driver or passengers from viewing the image information and preventing them from monitoring the scenery outside the vehicle.

[0067] Fig. 13 shows the effect of transparent sheet 51' in this case. As is clear from this figure, transparent sheet 51' is composed of polarizing plate 57, transparent diffusion sheet material 55, and retardation plate 58, and like transparent sheet 51, reflects S-polarized waves of sunlight incident from an oblique direction and transmits P-polarized waves, thereby reducing the illuminance of the sunlight. At this time, retardation plate 58 rotates the polarization axis of the P-polarized light, causing polarizing plate 57 to absorb a portion of the sunlight. As a result, damage to image display device 48 caused by 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 window 6' and returns to the inside of the vehicle. This light obstructs the driver's view and causes a hindrance to driving. Therefore, in this embodiment, a retardation plate 58 is disposed between the rear window 6' and the polarizing plate 57, and the reflected light is absorbed by 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 driver or passengers inside the vehicle from monitoring the scenery outside the vehicle, thereby preventing driving. The haze (HAZE), defined by the ratio of the diffuse transmittance and parallel light transmittance of the transparent sheet 51' described above, is practically acceptable if it is 10% or less, but is preferably 4% or less. On the other hand, the HAZU of a windshield for an automobile is 2% or less.

[0069] As described above, displaying information to the outside of the vehicle using a part of the shield glass such as the windshield 6, the rear window 6' or the side window 6" would be suitable for displaying information such as "Vacant" indicating the vacant status of a taxi to pedestrians on the road. As described 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 a large vehicle such as a bus or train, it is possible to display various information including advertisements and notices by using projection members such as the rear window 6' or the side window 6" (see FIG. 1), which are shield glass constituting the vehicle. The configuration and operation of the vehicle information display system when displaying information to the outside of the vehicle will be described below.

[0070] FIG. 14 shows another modified example in which information is displayed to, for example, pedestrians outside the vehicle via the rear window 6' of the vehicle 1 as a projection member that constitutes part of the vehicle. As a result, the driver and passengers can monitor the necessary information on the windshield 6 (see FIG. 9), and at the same time, the information can be displayed outside the vehicle via the rear window 6'. Note that the driver and passengers cannot monitor the information displayed to the outside, and therefore the driver's field of vision is not obstructed. In other words, the display of information to the outside of the vehicle does not prevent the driver and passengers inside the vehicle from monitoring the scenery outside.

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

[0072] In this example, the image display area of ​​the rear window 6' is naturally provided with the transparent sheet 51' shown in FIG. 13. In addition, the projected member on which the image information is displayed in one direction toward the outside of the vehicle is not limited to the windshield 6 or rear window 6' described above, and it is also possible to use, for example, the side window 6" (see FIG. 1) constituting the side of the vehicle. In that case, although not shown here, the image display device 48 is disposed on a member (e.g., an adjacent ceiling surface or a part of the window frame) near the side window 6", and the image display area of ​​the side window 6" is naturally provided with the transparent sheet 51' shown in FIG. 13. Displaying information on the side window 6" would be suitable for displaying messages such as "Sorry to keep you waiting" or "Please get in" to passengers on the road in a taxi.

[0073] In addition, in the above-mentioned examples, the vehicle information display devices 100, 100', 100" are described which display the image information to be displayed in one direction, either to the outside or the inside of the vehicle, via the windshield 6, rear window 6', or side window 6", which are projected members constituting the vehicle. However, the present invention is not limited to these, and for example, it is also possible to appropriately combine the vehicle information display device 100 which displays information inside the vehicle with the vehicle information display device 100' which displays information to the outside of the vehicle. According to this, for example, when applied to public transportation such as a bus or a train, 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, this cannot be seen from inside the vehicle), and useful information can be displayed to the public.

[0074] Although various embodiments have been described above in detail, the present invention is not limited to the above-described embodiments, and various modified examples are included. For example, the above-described embodiments are detailed descriptions of the entire system in order to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the configurations described. In addition, 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. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0075] 1...automobile (vehicle) body, 6...front windshield, 6'...rear windshield, 6"...side windshield, 100...vehicle information display device, 101...light source device, 48...image display device (image projection device), 50...protective cover, 50a...membrane or film, 50b...wavelength plate, 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, comprising: A display panel that emits image light; a polarizing plate that absorbs a specific polarized wave included in the image light emitted from the display panel; The image light emitted from the display panel and having the specific polarized wave absorbed is reflected by a shield glass of the vehicle, thereby displaying the image generated by the display panel as a virtual image toward the driver of the vehicle, and a light beam travels from the display panel toward a display area of ​​the shield glass of the vehicle, and the traveling direction of the light beam from the display panel is inclined in a direction away from the driver of the vehicle, The image display area of ​​the shield glass is a range in which the bonnet of the vehicle is monitored. Display device.

2. 2. The display device according to claim 1, A protective cover having a membrane or film that absorbs or reflects polarized wave components from outside the vehicle is provided. Display device.

3. 3. The display device according to claim 2, A retardation plate is disposed on the light emission side of the membrane or film of the protective cover. Display device.

4. 2. The display device according to claim 1, a protective cover provided on a light exit surface of the display panel to reduce surface reflection of external light; Display device.

5. 2. The display device according to claim 1, the polarizing plate is disposed between the display panel and the shield glass. Display device.

6. 2. The display device according to claim 1, A second polarizing plate is disposed on the incident side of the display panel. Display device.

7. 2. The display device according to claim 1, A linear Fresnel lens is disposed between the display panel and the shield glass. Display device.

8. 2. The display device according to claim 1, The shield glass is a window glass. Display device.

9. 2. The display device according to claim 1, The shield glass is a rear glass or a side glass. Display device.

Images