Information display device

Abstract

To provide an information display device capable of showing navigation or smartphone information to a driver without an eye point largely separating from a road surface.SOLUTION: An information display device comprises: a backlight device that generates an illumination light beam having strong directivity; a display panel that modulates the illumination light beam having strong directivity from the backlight device according to video information and emits it to a front glass; and a light conversion panel that is disposed at part of the front glass and converts the video light from the display panel so as to be recognized by an observer as a reflection image ahead of the front glass.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to an information display system that projects an image onto the windshield or combiner of a vehicle such as an automobile, a train, or an airplane (hereinafter collectively referred to as a "vehicle"), and a vehicle information display device that reflects the image by folding it back with the windshield like a mirror to observe a real image or a virtual image, and to the information display device.

Background Art

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

[0003] In this type of information display device, while it is desirable to expand the area where the driver can view the virtual image, it is also an important performance factor that the virtual image has high resolution and high visibility.

[0004] The head-up display device provides a virtual image as an enlarged image to the driver using an optical system including a concave mirror (function of a convex lens) for the video displayed on the video display device, and the windshield or combiner is always necessary as the final reflecting surface.

[0005] As the video display device used in the above-described head-up display device, a liquid crystal display element (liquid crystal display panel) is often used because high-quality video can be easily obtained and it is inexpensive. On the other hand, for miniaturization of the set, a small liquid crystal display element is used, so the resolution of the projected image obtained is insufficient, and for example, a new problem has become clear that it is not suitable for displaying high-resolution video displayed on a smartphone or the like.

[0006] The present invention relates to a vehicle information display system that uses a video information display device in combination with different technical means for each video display area with respect to an external landscape viewed by a driver through a windshield in order to supplement the resolution of the above-described head-up display device, and to technical means for realizing an information display device including an information display device for providing high-resolution video information to the driver used in such a system.

[0007] Further, according to Patent Document 2 below, in order to protect an inexpensive liquid crystal display panel used as a video source of an information display device from damage caused by sunlight, a transmissive-reflective member (hot mirror) that passes display light from the liquid crystal display panel and reflects infrared rays is provided in a non-parallel state at a distance in front of the liquid crystal display panel. A head-up display device is already known.

[0008] On the other hand, as a head-up display device having a different structure, a device for attaching a main body including a combiner near the ceiling (sun visor) of an automobile as disclosed in Non-Patent Document 1 below has already been proposed. However, if the HUD device comes off during a collision accident, there is a possibility of injuring the driver, and there are still safety issues. Therefore, it is considered that the method of directly reflecting video light on the windshield will become the mainstream as the head-up display device in the future.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0010]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] In the example of the head-up display device disclosed in Patent Document 1, which is the above-described prior art, it includes a device for displaying an image and a projection optical system for projecting the image displayed on the display device. As the projection optical system, it has a first mirror and a second mirror in the optical path from the display device to the viewer. By satisfying the relationship between the incident angle in the major axis direction of the image on the first mirror, the incident angle in the minor axis direction of the image on the first mirror, the distance between the image display surface of the display device and the first mirror, and the horizontal width of the virtual image viewed by the viewer under a predetermined condition, the device is realized. However, no specific solution means for the above-described high-definition of the video has been shown. Moreover, regarding a new problem that sunlight passes through the front glass and is condensed by the concave mirror under predetermined daytime conditions, causing image damage to the liquid crystal panel and the polarizing plate and significantly reducing the performance, there is not even a description thereof.

[0012] In the future, it is considered that the method using the front glass as a reflecting surface described in Patent Document 1 above will become the mainstream. However, no consideration has been given at all to the response to the high-definition of the display video of information terminals represented by smartphones. In addition, for the practical application of vehicle information display devices, which is a very important problem, there is no consideration at all for countermeasures against the so-called burning (carbonization) that occurs under predetermined daytime conditions, where sunlight transmitted through the front glass and condensed by the concave mirror is condensed on the polarizing plate or the liquid crystal panel itself provided on the light emission side of the liquid crystal display device, and the normal function cannot be performed due to the heat and light intensity of the sunlight causing deterioration.

[0013] Similarly, also in the technology disclosed in Non-Patent Document 1 where the final reflecting surface is a combiner, no consideration has been given at all to the high-definition of the display video or the new problem that when the video display element is a liquid crystal panel, sunlight passes through the front glass and the combiner and is condensed by the concave mirror under predetermined daytime conditions, causing damage to the liquid crystal panel and the polarizing plate and significantly reducing the performance.

[0014] Furthermore, in Patent Document 2, in order to reduce the risk of damage to the liquid crystal display panel by sunlight, it has been proposed to dispose a transmissive reflection member (hot mirror) for selectively reflecting the infrared rays of sunlight on the optical path. However, the incident sunlight includes not only infrared rays but also light rays in the visible region and the ultraviolet region. In order to reduce the damage to the liquid crystal display element and the polarizing plate caused by sunlight, it was not sufficient to only reduce the infrared rays. Furthermore, regarding the new problem that the quality of the video visually recognized by the driver, particularly the contrast performance and the apparent resolution, are significantly reduced due to the adverse effects caused by the intrusion of external light including visible light, and the response to the high resolution of the display video, no consideration has been given at all.

[0015] As described above, in the head-up display device as an information display device that provides video information to the driver according to the above-described prior art, in order to obtain a display video with high resolution, it is necessary to use a large liquid crystal display element. Therefore, the first problem has become clear that it is impossible to achieve both miniaturization and high resolution of the device.

[0016] Furthermore, in the liquid crystal panel used as the video display device of the head-up display device, when actually mounted in a vehicle, sunlight passes through the windshield under predetermined daytime conditions and is condensed by the concave mirror, damaging the liquid crystal panel and the polarizing plate. As a result, the second problem has also become clear that the performance is significantly reduced.

[0017] The present invention has been made in view of the problems in the above-described prior art. More specifically, an object of the present invention is to provide an in-vehicle information display system capable of achieving both miniaturization and high resolution of the device and being practical, and an information display device therefor.

Means for Solving the Problem

[0018] In the present invention, in order to achieve the above-described object, there is provided an information display system that reflects image light on the windshield of a vehicle to display image information to a viewer, the system including: a first information display device that reflects the image light on the windshield to cause the viewer to view a virtual image; and a second information display device that reflects the image light on the windshield to cause the viewer to view a reflected image, wherein the resolution of the image displayed by the first information display device is lower than the resolution of the image displayed by the second information display device.

[0019] Further, in the present invention, there is provided an information display device for configuring an information display system that reflects image light on the windshield of a vehicle to display image information to a viewer, the device including: an image light generation means for generating image light for displaying image information inside a housing having an opening in part thereof; an image light processing means for performing a predetermined optical process on the image light from the image light generation means; and a projection means for projecting the image light from the image light processing means through the opening of the housing so that the viewer can recognize the image information as a virtual image in front of the windshield.

[0020] Furthermore, in the present invention, there is provided an information display device for configuring an information display system that reflects image light on the windshield of a vehicle to display image information to a viewer, the device including: a backlight device for generating a strongly directional illumination light beam; a display panel for modulating the strongly directional illumination light beam from the backlight device according to the image information and emitting it to the windshield; and a light direction conversion panel provided on a part of the windshield for converting the image light from the display panel so that the viewer can recognize it as a reflected image in front of the windshield.

Advantages of the Invention

[0021] According to the present invention described above, as an information display device that obtains video information reflected by the windshield on the external scenery viewed through the windshield when the driver drives the vehicle, a virtual image with a large screen is displayed in the distance in a partial area of the windshield by a head-up display device. On the other hand, for example, in the lower end area of the windshield, a vehicle information display system can be provided in which the video of a large-size high-resolution video display device is reflected by the windshield and the reflected image can be directly viewed by the driver and passengers. As a result, the driver can appropriately display videos with different resolutions and video sizes on the windshield for the necessary information.

[0022] On the other hand, according to the present invention described above, while realizing miniaturization of the head-up display device, it corrects distortion and aberration of the virtual image observed by the driver due to external light including sunlight, and at the same time, by the concave mirror forming the virtual image optical system, it is possible to reduce the damage to the liquid crystal panel, polarizing plate, etc., which are video display devices, caused by the external light including sunlight (mostly P-polarized wave component) incident through the windshield and reduce the performance degradation. That is, it is possible to provide an information display device for a vehicle information display system that reduces the adverse effects caused by light with a wide range of wavelengths included in the external light including sunlight and forms a virtual image with excellent performance.

Brief Description of the Drawings

[0023]

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Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings and the like. It should be noted that the present invention is not limited to the following description, and various changes and modifications can be made by those skilled in the art within the scope of the technical idea disclosed in this specification. Also, in all the drawings for explaining the present invention, those having the same function are denoted by the same reference numerals, and repeated explanations thereof may be omitted.

[0025] <Overview of Vehicle Information Display System> Figure 1(a) is a top view of an information display device 100 according to an embodiment of the present invention described later, mounted on an automobile, in particular. In front of the driver's seat of the automobile 1010, there is a windshield 6 as a projection member. The inclination angle of this windshield 6 with respect to the vehicle body varies depending on the type of the automobile. Furthermore, the inventors investigated the radius of curvature in order to realize an optimal virtual optical system. As a result, as shown in Figure 1(b), the windshield 6 has different horizontal radii of curvature Rh with respect to the ground surface of the automobile and vertical radii of curvature Rv with respect to the horizontal axis, and it was found that the following relationship generally holds between Rh and Rv. Rh > Rv It was also found that the difference in the radius of curvature, that is, Rh with respect to Rv, is often in the range of 1.5 times to 2.5 times.

[0026] In the present invention, when the driver drives his / her own vehicle, video information is displayed by reflecting it on the windshield on the external landscape viewed through the windshield. The information display device divides the windshield into a plurality of regions, and in a part of the regions, a large virtual image is displayed in the distance by a head-up display device. On the other hand, for example, in the lower end region of the windshield, the video of a large-sized high-resolution video display device is reflected by the windshield, and the reflected image is directly viewed by the driver and passengers. As a result, an information video system is provided in which the driver can appropriately display necessary information with different resolutions and video sizes according to the display region of the windshield.

[0027] A head-up display device as an example thereof is an information display device that displays video information as a virtual image on a projection surface, and includes, inside a housing having an opening in part, video light generation means for generating video light for displaying video information, means for performing predetermined optical processing on the video light from the video light generation means, and means for projecting the video light from the video light processing means onto the projection surface through the opening of the housing so that a viewer can recognize the video information as a virtual image in front of the projection surface. An information display device is provided.

[0028] More specifically, although described in detail below, in the information display device of the present invention, a polarizing plate that absorbs P-wave sunlight is provided on a glare stop 41 provided at the opening. That is, the polarizing plate absorbs P-polarized sunlight and transmits S-polarized sunlight. The polarizing plate is, for example, a λ / 4 plate, a λ / 8 plate, or a λ / 16 plate. By causing the glare stop 41 to absorb the P-wave component, the following effects can be obtained. (1) By absorbing the P-polarized sunlight component that has passed through the front glass under predetermined daytime conditions (and then passing through the combiner in the combiner method) in front of the concave mirror, the sunlight that has passed through the front glass is prevented from returning to the liquid crystal panel and the polarizing plate. (2) When the information display device is not in use, by rotating the concave mirror at a predetermined angle so that sunlight does not return to the video display device, it is possible to prevent the sunlight condensed by the concave mirror from returning to the video display device.

[0029] Furthermore, a large high-resolution video display device is provided at the position of the dashboard corresponding to the video display area in the lower end area of the front glass, and an information video system is provided in which the display video is reflected by the front glass and the reflected image is directly viewed by the driver and passengers. A transparent screen having an effect of scattering video light is provided on the front glass corresponding to the video display position, and by efficiently reflecting the video, the video can be provided to the driver and passengers with a practical level of image quality. Since the large high-resolution video display device described above has a high brightness, by controlling the emission direction of the video light, it is possible to prevent the video light from directly entering the eyes of the driver and passengers.

[0030] <First information display device of vehicle information display system> FIG. 2 is a schematic configuration diagram showing the peripheral device configuration of the first information display device of the vehicle information display device of the present invention. Here, as an example, an information display device 100 that projects an image onto the windshield 6 of an automobile will be described. The head-up display device as the information display device 100 according to an embodiment of the present invention forms a virtual image V1 in front of the host vehicle at the driver's line of sight (eye point: described in detail later) 8, and thus displays various information reflected by the projection member (in this embodiment, the inner surface of the windshield 6) as a virtual image VI (Virtual Image) (so-called HUD (Head up Display)). The illustrated control device 40 constituting such a HUD device acquires various information such as the speed limit, the number of lanes of the road corresponding to the current position where the host vehicle is traveling, and the planned travel route of the host vehicle set in the navigation system 61 from the navigation system 61 as foreground information (that is, information to be displayed in front of the host vehicle by the above virtual image).

[0031] Further, the illustrated driving support ECU 62 is a control device for realizing driving support control by controlling the drive system and the control system according to an obstacle detected as a result of monitoring by the peripheral monitoring device 63. Such driving support control includes, for example, well-known techniques such as cruise control, adaptive cruise control, pre-crash safety, and lane keeping assist.

[0032] The illustrated peripheral monitoring device 63 is a device that monitors the situation around the host vehicle. As an example, it includes a camera that detects an object existing around the host vehicle based on an image of the periphery of the host vehicle, and a detection device that detects an object existing around the host vehicle based on the result of transmitting and receiving a probing wave.

[0033] The control device 40 of the HUD device described above acquires such information (for example, the distance to the preceding vehicle, the orientation of the preceding vehicle, the positions where obstacles and signs exist, etc.) from the driving support ECU 62 as foreground information. Further, an ignition (IG) signal and vehicle state information are input to this control device 40. Among these pieces of information, the vehicle state information is information acquired as vehicle information and does not require a high-resolution display. For example, it includes warning information indicating that a predefined abnormal state has occurred, such as the remaining fuel amount of the internal combustion engine and the temperature of the cooling water. Also included are the operation result of the direction indicator, the traveling speed of the host vehicle, and further, shift position information, etc. The control device 40 described above starts up when an ignition signal is input. The above is the description of the entire information display device system of this embodiment.

[0034] Note that the projection member may be any member on which information is projected, and it may be not only the front glass 6 described above but also a combiner, for example. That is, in the information display device 100 of this embodiment, it is sufficient that a virtual image is formed in front of the host vehicle in the driver's line of sight 8 and is made visible to the driver.

[0035] In the information display device 100 having the above-described configuration, there is provided a video display device 4 that projects video light for displaying information, and a correction lens element 2 for correcting distortion and aberration that occur when a virtual image is formed by the concave (free-form surface) mirror 1 for the video displayed on the video display device 4. The video light beam from this information display device 100 is emitted from an opening (not shown) toward the front glass 6.

[0036] Further, the information display device 100 further includes a control device 40 that controls the video display device 4 and its backlight. Note that the optical components including the video display device 4 and the backlight, etc. are the virtual image optical system described below and include the concave mirror 1 that reflects light. Also, the light reflected in this optical component is reflected by the front glass 6, which is the projection member, and travels toward the driver's line of sight 8.

[0037] Note that as the above-described video display device 4, for example, in addition to an LCD (Liquid Crystal Display) having a backlight, there is a self-luminous VFD (Vacuum Flourescent Display) or the like.

[0038] On the other hand, instead of the above-described video display device 4, an image may be displayed on a screen by a projection device, and the virtual image may be formed by the concave mirror 1 and reflected by the front glass 6 or a combiner (not shown) which is a projection member, and directed toward the driver's viewpoint 8.

[0039] Here, in order to reduce the distortion of the virtual image, the shape of the concave mirror 1 is such that in the upper part shown in FIG. 1 (the region where the light rays are reflected below the front glass 6 which is relatively close to the driver's viewpoint 8), the relative curvature radius is small so that the magnification is large, and on the other hand, in the lower part (the region where the light rays are reflected above the front glass 6 which is relatively far from the driver's viewpoint), the relative curvature radius is large so that the magnification is small. Further, by tilting the video display device 4 with respect to the optical axis of the concave mirror 1, the distortion generated by correcting the difference in the virtual image magnification described above can be reduced, and even better correction can be achieved.

[0040] On the other hand, as shown in FIG. 1(b), the front glass 6 of a passenger car has different curvature radii Rv in the vertical direction of the main body and Rh in the horizontal direction, and generally, the relationship is Rh > Rv. For this reason, when the front glass 6 is regarded as a reflecting surface, it becomes a toroidal surface of the concave mirror 1. Therefore, in the information display device 100 of the present embodiment, the shape of the concave mirror 1 may be such that the virtual image magnification due to the shape of the front glass 6 is corrected, that is, the average curvature radii may be different in the horizontal direction and the vertical direction so as to correct the difference in the curvature radii in the vertical direction and the horizontal direction of the front glass 6. At this time, when the shape of the concave mirror 1 is a spherical or aspherical surface (shown in [Equation 2] below) symmetric with respect to the optical axis, since the horizontal cross-sectional shape and the vertical cross-sectional shape at a distant location cannot be controlled individually, it is preferable to correct it as a free-form surface shown in [Equation 1] below as a function of the surface coordinates (x, y) of the mirror surface from the optical axis.

[0041]

Number

[0042]

Number

[0043] <Intrusion of sunlight into the device and its suppression principle> Next, the intrusion of sunlight into the above-described information display device in the driver's seat of the vehicle will be described. FIG. 3 shows the state in the vicinity of the driver's seat of the vehicle. The above-described information display device 100 is disposed below the windshield 6 attached between the hood 44 and the ceiling plate 45 constituting the vehicle body, for example, on the back side (the rear hood side) of the dashboard including instruments such as the speedometer 42. In this figure, the vehicle's steering wheel 43 and the eyes 8 of the viewer who is the driver are shown, and the daytime sun 60 is shown above the vehicle. FIG. 4 mainly shows the sun 60, the windshield 6, and the eyes 8 of the viewer taken out from the configuration of FIG. 3, and FIG. 5 shows the configuration housed in the housing 7 of the information display device 100.

[0044] In FIGS. 3 and 4, the strong light from the sun 60 is incident on the vehicle's windshield 6 at an incident angle θ1 as indicated by the white arrow. After a part of the light is reflected by the windshield 6, the remaining light passes through the glare stop 41 (see FIG. 5) provided at the opening provided in the upper part of the information display device 100 to block the reflected light unrelated to the image reflected by the optical elements and structures disposed inside the housing and enters the inside of the device. At this time, as is clear from FIG. 4, particularly at an incident angle of 50 degrees or more, most of the S-polarized component (S-wave) of the sunlight is reflected on the above-described windshield 6 as shown in FIG. 4. As a result, most of the sunlight entering the information display device 100 becomes the P-polarized component (P-wave).

[0045] On the other hand, as indicated by the solid arrows in FIGS. 3 and 4, the video light emitted from the information display device 100 is reflected by the front glass 6 or a combiner (not shown) and then enters the viewer's eyes 8.

[0046] More specifically, natural light such as sunlight is not only light in a wide wavelength range from ultraviolet to infrared as shown in FIG. 17, but also exists in a state where two types of polarized light directions (hereinafter referred to as S-polarized light and P-polarized light), i.e., light with a vibration direction perpendicular to the light propagation direction and light with a horizontal direction, are mixed. As described above, in the region where the incident angle to the front glass 6 exceeds 50 degrees, as shown in FIG. 16, the reflectance on the glass surface varies depending on S-polarized light, P-polarized light, and further, the incident angle.

[0047] Therefore, in this embodiment, based on the findings by the inventors described above, that is, considering that most of the sunlight entering through the front glass 6 is the P-polarized light component, in order to suppress external light including sunlight entering the information display device 100, it is particularly confirmed that reducing the P-wave component is effective. In addition, it is effective to use the S-wave component as the video light projected from the information display device 100.

[0048] <Specific Embodiment of the First Information Display Device> Subsequently, the specific optical configuration of the information display device 100 configured based on the above findings will be described below.

[0049] The configuration of the information display device 100 as an embodiment of the present invention will be described with reference to FIG. 3. A lens element 2, for example, is disposed as a transmissive optical component between the video display device 4 and the concave mirror 1. The lens element 2 corrects the distortion aberration of the virtual image obtained in accordance with the shape of the concave mirror 1 by controlling the emission direction of the light rays to the concave mirror 1, and at the same time corrects the aberration including the astigmatism caused by the difference between the horizontal curvature radius and the vertical curvature radius of the front glass 6 described above.

[0050] In addition, in order to further enhance the aberration correction ability, the above-described lens element 2 may be composed of a plurality of lenses. Alternatively, instead of the lens element 2, a curved surface (free-form surface) mirror may be arranged, and while using the curved surface mirror to fold the optical path, by controlling the incident position of the light beam on the concave mirror 1, it is also possible to reduce the distortion aberration. As described above, furthermore, it goes without saying that even if an optical element optimally designed to improve the aberration correction ability is provided between the concave mirror 1 and the image display device 4, it does not depart from the technical idea or scope of the present invention. Further, by changing the thickness of the lens element 2 in the optical axis direction described above, in addition to the original aberration correction, the optical distance between the concave mirror 1 and the image display device 4 can be changed, and the display position of the virtual image can be continuously changed from a distant position to a proximity position.

[0051] The sunlight poured in from outside the vehicle is reflected by the S polarization component by the windshield 6, and the P polarization component is transmitted into the vehicle and enters the information display device 100 from the opening. On one side of the glare stop 41 provided at the opening, a polarizing plate that absorbs the P wave component of the incident sunlight and transmits the S polarization is provided. Further, on the other surface of the glare stop 41 or the sunlight incident surface of the polarizing plate, a reflective film that reflects light in the ultraviolet region and the infrared region is provided. As a result, the P polarized wave in the visible light region and most of the light in the ultraviolet region and the infrared light region do not enter the image display device 4, and as a result, the damage to the image display device 4 caused by sunlight is reduced.

[0052] On the other hand, as a factor that degrades the image quality of the information display device 100, it is known that the image light beam emitted from the image display device 4 toward the concave mirror 1 is reflected on the surface of the lens element 2 arranged in the middle and returns to the image display device 4, and is reflected again and superimposed on the original image light, degrading the image quality. Therefore, in this embodiment, not only is an antireflection film formed on the surface of the lens element 2 to suppress reflection, but furthermore, either one or both of the image light incident surface and the light exit surface of the lens element 2 are shaped such that the above-described reflected light does not converge on a part of the image display device 4 (for example, a shape with a concave surface facing the image display device 4), and it is preferable to design with constraints on the surface shape.

[0053] On the side of the image display device 4 of the polarizing plate of the glare stop 41 described above, a λ / 16 plate (optimally selected as λ / 4, λ / 8, etc. in consideration of brightness) is provided, and further, a mechanism for adjusting its mounting angle is provided. For example, by moving it to the position indicated by the dashed line in the figure, the polarization angle of the S-polarized image light output from the image display device 4 is changed. As a result, even if the driver wears polarized sunglasses, by appropriately changing the mounting angle of the wave plate provided on the glare stop 41 of the present invention, a virtual image with sufficient brightness and excellent color comprehensiveness can be obtained.

[0054] Also, even if the polarizing plate provided on the glare stop 41 absorbs the P-polarization component of the sunlight incident inside the vehicle, since the area of the polarizing plate that receives light is the same as the opening, the reliability is not impaired. Further, since this polarizing plate selectively transmits S-polarization, it also has the effect of improving the contrast performance of the virtual image obtained by the information display device 100.

[0055] On the other hand, as the light source device 10 used in the information display device 100 of the present invention shown in FIGS. 5 and 6, it is preferable to employ a solid light source with a long product life. For example, the light source device 10 includes an LED (Light Emitting Diode) with little change in light output with respect to fluctuations in the ambient temperature, and a polarizing beam splitter (PBS) provided with optical means for reducing the light divergence angle, and it is preferable to perform polarization conversion by the PBS.

[0056] Polarizing plates (not shown here) are arranged on the backlight side (light incident surface) and the lens element 2 side (light exit surface) of the liquid crystal panel, thereby increasing the contrast ratio of the image light. If an iodine-based polarizing plate with a high degree of polarization is employed for the polarizing plate provided on the backlight side (light incident surface), a high contrast ratio can be obtained. On the other hand, by using a dye-based polarizing plate on the lens element 2 side (light exit surface), high reliability can be obtained even when external light is incident or the ambient temperature is high.

[0057] When a liquid crystal panel is used as the image display device 4, particularly when the driver is wearing polarized sunglasses, there is a problem that a specific polarization wave is blocked and the image cannot be seen. To prevent this, as described above, a λ / 4 plate, a λ / 8 plate, or a λ / 16 plate is disposed on one side surface of the glare stop 41 provided at the opening so that the glare generated inside the information display device does not return to the driver's line of sight. By this plate, the glare is aligned in a specific polarization direction. Further, by rotating the glare stop 41 from the position shown in FIG. 5 to the position 46 shown by the broken line in FIG. 6, the polarization angle of the image light is appropriately changed, converted into circular polarization, or the polarization axis of the linear polarization is rotated to have a polarization axis different from the polarization direction of the polarized sunglasses. On the other hand, when the polarization axis is rotated to approach circular polarization, the reflectance by the front glass 6 decreases because the polarization axis of the image light from the information display device rotates from S polarization, and the brightness of the image decreases. Therefore, it is preferable to select by taking a balance between the two.

[0058] The inventors experimentally found that in order to reduce the color unevenness of the image obtained at this time (the color uniformity of the entire screen in the full-screen white display), it is effective to provide a predetermined wave plate at the position of the glare stop where the image light beam spreads the most.

[0059] <Second Information Display Device of Vehicle Information Display System> Subsequently, the specific optical configuration of the second information display device of the information display system of the present invention will be described below.

[0060] <Specific Embodiment of Second Information Display Device> As the information display device 48 which is the second information display device of the present invention, as also shown in FIGS. 3 and 7, for example, a high-resolution image (an image of a large high-resolution image display device) from a smartphone 300 or the like is reflected toward the viewer's eyes by a film (for example, a transparent film or a sheet) 51 provided on the surface of the front glass 6, so that an image is pseudo-displayed on the front glass.

[0061] Next, the configuration of the information display device 48 will be described with reference to FIG. 8. The video display element (liquid crystal display panel) 52 is composed of a relatively large liquid crystal display panel with a screen size exceeding 6 inches. Generally, since the radius of curvature of the front glass 6 often varies partially, uneven (vertical and horizontal) distortion occurs in the displayed image depending on the location where the image is reflected. Therefore, distortion correction is required to obtain a correct image when viewing the reflected image from the viewing direction. To perform correction at a level that causes no practical problems by this distortion correction, the resolution of the panel needs to be 1280 × 720 dots or more.

[0062] FIG. 9 shows, together with the video display element 52, a light source device 101 that constitutes its light source, as a developed perspective view, below it. This video display element (liquid crystal display panel) 52 obtains a strongly directional illumination light beam by the light source device 101 which is a backlight device, and emits modulated video light according to the video signal toward the film 51 provided on the front glass 6. In this FIG. 9, the information display device 48 includes, together with the video display element 52, an optical direction conversion panel 54 and a second diffusion plate 18b that control the directivity characteristics of the emitted light beam 30 from the light source device 101. That is, polarizing plates are provided on both sides of the information display device 48 (see FIG. 8), and the video light of a specific polarization is modulated in light intensity by the video signal and emitted. Thereby, a high-resolution video (video of a large high-resolution video display device) from a smartphone 300 or the like is projected onto the front glass 6 and reflected toward the viewer's eyes by the film 51 provided on its surface.

[0063] Further, the light source device 101 is formed of, for example, plastic or the like. The light source device 101 includes a case of the light source device 101 (see FIG. 8) that houses therein an LED, a collimator, a composite diffuser block, a light guide, etc., which will be described in detail later. An information display device 48 and a video display element 52 are attached to the upper surface of the light source device 101. Also, an LED (Light Emitting Diode) element, which is a semiconductor light source, and an LED substrate 102 (see FIGS. 9-10) on which its control circuit are mounted are attached to one side surface of the case of the light source device 101. A heat sink 103 for cooling the heat generated by the LED element and the control circuit is attached to the outer surface of the LED substrate 102 (see FIG. 8).

[0064] On the other hand, the video display element 52 attached to the upper surface of the light source device 101 is composed of a liquid crystal display panel frame, a liquid crystal display panel attached to the frame, and further, an FPC (Flexible Printed Circuits) 403 (see FIG. 8) electrically connected to the panel. That is, although the video display element 52 will be described in detail later, together with the LED element, which is a solid light source, a video to be displayed is generated and controlled by a control signal from a control circuit (not shown here) that constitutes an electronic device.

[0065] Subsequently, the configuration of the light source device 101, that is, the optical system housed in the case of the light source device 101 will be described in detail below with reference to FIGS. 9 and 10.

[0066] Figures 9 and 10 show a plurality (two in this example) of LEDs 14a and 14b (not shown here) that constitute a light source, and these are attached to a predetermined position with respect to the LED collimator 15. Note that each of these LED collimators 15 is formed of a light-transmitting resin such as acrylic, for example. And as shown in Fig. 10(b), this LED collimator 15 has an outer peripheral surface 156 of a conical convex shape obtained by rotating a parabolic cross-section, and at its top, it has a concave portion 153 formed with a convex lens portion (i.e., convex lens surface) 157 at its central portion. Also, at the central portion of the convex lens portion 157, it has a convex lens surface (or it may be a concave lens surface recessed inward) 154 that protrudes outward. Note that the outer peripheral surface 156 that forms the conical outer peripheral surface of the LED collimator 15 is set within a range of angles that can totally reflect the light emitted from the LED 14a in the peripheral direction inside it, or a reflecting surface is formed.

[0067] On the other hand, the LEDs 14a and 14b are respectively arranged at predetermined positions on the surface of a so-called LED substrate 102, which is their circuit board. This LED substrate 102 is arranged and fixed with respect to the LED collimator 15 such that the LEDs 14a or 14b on its surface are respectively positioned at the central portions of the concave portions 153.

[0068] According to such a configuration, among the light emitted from the LED 14a or 14b, particularly the light radiated upward (right direction in the figure) from its central portion, is condensed by the convex lens portion 157 and the convex lens surface 154 that form the outer shape of the LED collimator 15 to become parallel light. Also, the light emitted from other portions in the peripheral direction is reflected by the parabolic surface that forms the conical outer peripheral surface of the LED collimator 15 and is similarly condensed to become parallel light. In other words, according to the LED collimator 15 that has a convex lens formed at its central portion and a parabolic surface formed at its peripheral portion, almost all of the light generated by the LED 14a or 14b can be taken out as parallel light, and it becomes possible to improve the utilization efficiency of the generated light.

[0069] Note that a polarization conversion element 21, which will be described in detail below, is provided on the light emitting side of the LED collimator 15. As is clear from the figure, this polarization conversion element 21 is composed of a columnar light transmissive member (hereinafter referred to as a parallelogram column) having a parallelogram cross section and a columnar light transmissive member (hereinafter referred to as a triangular column) having a triangular cross section, and is configured by arranging a plurality of them in an array parallel to a plane orthogonal to the optical axis of the parallel light from the LED collimator 15. Further, a PBS film 211 and a reflection film 212 are alternately provided at the interfaces between adjacent light transmissive members arranged in this array. Also, a 1 / 2λ phase plate 213 is provided on the emission surface from which the light that has entered the polarization conversion element 21 and passed through the PBS film 211 is emitted.

[0070] A rectangular composite diffusion block 16 shown in Fig. 10(a) is further provided on the emission surface of this polarization conversion element 21. That is, the light emitted from the LED 14a or 14b becomes parallel light by the action of the LED collimator 15 and enters the composite diffusion block 16, and after being diffused by the texture 161 on the emission side, it reaches the light guide 17 described below.

[0071] The light guide 17 is a member formed in a rod shape having a substantially triangular cross section (see Fig. 10(b)) by a light transmissive resin such as acrylic. As is clear from Fig. 10(a), 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 reflection portion (light guide light reflection surface) 172 forming an inclined surface, and a light guide light emission portion (light guide light emission surface) 173 facing the liquid crystal display panel including the video display element 52 via a second diffusion plate 18b are provided.

[0072] As shown in Fig. 9 which is a partial enlarged view of the light guide light reflecting portion 172 of this light guide 17, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape. And the reflecting surface 172a (the line segment rising to the upper right in the figure) forms an angle αn (n is a natural number, and in this example, for example, it is from 1 to 130) with the horizontal plane indicated by the dashed-dotted line in the figure. As an example, here, αn is set to 43 degrees or less (however, 0 degrees or more).

[0073] As a result, the light guide light incident portion 171 is formed in a curved convex shape inclined toward the light source side. According to this, the parallel light from the light emitting surface of the composite diffusion block 16 is diffused through the first diffusion plate 18a and enters the light guide 17. As is clear from the figure, it reaches the light guide light reflecting portion 172 while being slightly bent (deflected) upward by the light guide light incident portion 171.

[0074] As described in detail above, according to the information display device 48 according to the present invention described above, while improving the light utilization efficiency and its uniform illumination characteristics, it is possible to manufacture it in a small size and at low cost including the modularized S-polarized light source device. In the above description, the polarization conversion element 21 has been described as being attached after the LED collimator 15, but the present embodiment is not limited thereto, and those skilled in the art will understand that the same effects can also be obtained by providing it at any place in the optical path leading to the liquid crystal display panel.

[0075] Note that in this light guide light reflecting portion 172, a large number of reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape. The diffused light diffused through the first diffusion plate 18a is totally reflected on each reflecting surface 172a and goes upward. The diffused light going upward enters the light direction conversion panel 54 that controls the directivity characteristics as a parallel diffused light beam through the light guide light emitting portion 173 or the second diffusion plate 18b. With respect to this diffused light beam, the light direction conversion panel 54 performs light direction conversion on this diffused light beam. The diffused light beam after the light direction conversion exits from the light direction conversion panel 54 in, for example, the direction shown in Fig. 9 and enters the video display element 52 obliquely from the side.

[0076] FIG. 11 is a schematic explanatory diagram for explaining the principle of the light direction conversion panel 54 provided in the above-described information display device 48. The light beam from the light guide enters from the incident surface of the light direction conversion panel, and the light beam is refracted in a desired direction θ3 by the lens action of the linear Fresnel lens provided on the exit surface. 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 linear Fresnel lens, the Fresnel angle θ0 of the linear Fresnel lens, and the refractive index n of the base material. As a result, directivity can be given to the parallel light beam from the light guide in a desired direction.

[0077] Similarly, by providing a linear Fresnel lens having the structure shown in FIG. 11 on the light exit surface of the video display device 48, directivity is given in the direction of the front glass 6 that forms the reflection surface of the video light beam. As a result, even if the driver directly looks into the screen of the video display device 48, the video light does not directly reach the eyes, so there is no hindrance to driving. The pitch of the linear Fresnel lens is preferably 1 / 3 or less of the pixel pitch of the video display device 48. For example, in order to reduce moire generated by the pitch ratio of the pixel and the linear Fresnel lens to a level that causes no practical problem, the pitch of the linear Fresnel lens is preferably 1 / 7 or less of the pixel pitch. In addition, a protective cover (shown by a broken line) is provided on the surface to protect the linear Fresnel lens from wear and the like.

[0078] FIG. 12 is a cross-sectional view showing a schematic configuration of a protective cover 50 in contact with the dashboard 47 of the above-described information display device 48. A black stripe 59 is provided on a part of the light exit side of the substantially transparent base material 56. The black stripe 59 reduces surface reflection of external light including sunlight. For the black stripe 59, for example, a black paint containing carbon black is used. In addition, an antireflection film for suppressing surface reflection is provided on a portion where the black stripe is not provided. By the antireflection film, external light reflection on the surface of the protective cover 50 is significantly reduced, and the hindrance caused by external light reflection when the driver drives the own vehicle is reduced.

[0079] On the light incident side of the other, slightly transparent substrate 56, a film or a film 58 that absorbs or reflects the P-wave component of the solar light beam is formed or adhered. As a result, since the P-wave component of the sunlight does not enter the information display device 48, the reliability regarding light resistance and heat resistance is greatly improved. On the other hand, since the film 58 also has the characteristic of a filter that selectively transmits the S-polarized video light output from the information display device 48, the contrast performance of the obtained video is greatly improved.

[0080] Note that since the video source of the video display device 48 described above is a liquid crystal panel, similar to the information display device 100 described above, when the driver is wearing polarized sunglasses, there is a problem that a specific polarization wave is blocked and the video cannot be seen. To prevent this, a retardation plate 57 such as a λ / 4 plate, a λ / 8 plate, or a λ / 16 plate is disposed between the film 58 of the information display device 48 protection cover 50 and the substrate 56. By providing the retardation plate 57, the polarization direction of the light beam is aligned in a specific direction, and it is preferable that the polarization direction of the video light is set as an optimal polarization angle and the polarization axis of the polarized sunglasses is shifted by a desired amount.

[0081] On the other hand, when the polarization axis is rotated to approach circular polarization, the polarization axis of the video light from the information display device rotates from S polarization. For this reason, since the reflectance by the front glass 6 decreases and the brightness of the video decreases, it is preferable to select while taking the balance between the two.

[0082] <Specific Example of Vehicle Information Display System> An example of the arrangement inside the cockpit of an automobile in which the information display system of the present invention including the above-described information display device 100 and the information display device 48 is arranged is shown in FIG. 13. FIG. 13(a) shows a system corresponding to an automobile with a steering wheel arranged on the left side, and FIG. 13(b) shows a system corresponding to an automobile with a steering wheel arranged on the right side. In the image display area 1(a) of the figure, video information is reflected by the front glass 6 using the information display device 100, and the virtual image is viewed by the driver. In the image display area 1(b), the video information displayed on the information display device 48 is reflected by the front glass, and the real video is viewed by the driver. Note that the video information may be reflected by a combiner provided with a film 51.

[0083] As shown in FIG. 3, the information display device 100 and the information display device 48 are arranged between the front glass 6 and the steering wheel 43. Inside the dashboard 47, the video display device 48 and the information display device 100 are sequentially arranged from the front glass 6 toward the steering wheel 43. As a result, for the external scenery viewed by the driver through the front glass 6 when driving the vehicle, the front glass 6 is divided into a plurality of regions as an information display system that obtains video information reflected by the front glass 6. In a part of the regions, as the information display device 100, a large virtual image is displayed in the distance by a head-up display device, and on the other hand, for example, in the lower end region of the front glass (displaying a video within the range of the vehicle's bonnet), as a second information display device, the video of the large high-resolution information display device 48 is reflected by the front glass 6, and an information video system is provided in which the reflected image is directly viewed by the driver and passengers. As a result, the driver can appropriately display the necessary information with different resolutions and video sizes according to the display area of the front glass 6.

[0084] Note that a camera 72 for monitoring the state of the driver and the situation inside the automobile is provided in the rearview mirror 71 of FIG. 13, and for example, the emission direction of the video light from the above-described information display device is controlled according to the height of the driver's eyes.

[0085] FIG. 14 is a schematic diagram showing an information video system that provides video information to a passenger in the front passenger seat. Similar to FIG. 13, FIG. 14(a) shows a system corresponding to a vehicle with a steering wheel arranged on the left side, and FIG. 14(b) shows a system corresponding to a vehicle with a steering wheel arranged on the right side. In the image display area 1(a), video information is reflected by the front windshield using the information display device 100, and a virtual image is viewed by the driver. In the image display area 1(b), the video information displayed on the information display device 48 is reflected by the front windshield, and a real video is viewed by the driver. As a result, for the passenger, video information displayed by a device (not shown) having the same configuration as the video display device 48 is reflected in the image display area 1(c) of the front windshield, and a real video is viewed by the driver.

[0086] It is obvious that the film 51 (see FIG. 7) described above is adhered or bonded to the front windshield 6 corresponding to the image display area 1(b) and the image display area 1(c).

[0087] Next, the configuration of the film 51 will be described with reference to FIG. 15. Sunlight incident on the front windshield 6 (arranged horizontally for convenience of explanation) from an oblique direction reflects its S-polarized wave and transmits the P-polarized wave toward the film 51. The film 51 is composed of a polarizing plate 55b that transmits the S-wave and a transparent diffusion sheet 55a. The transparent diffusion sheet 55a is a film obtained by stretching while dissolving a thermoplastic polymer in which nanoparticles of zirconium or nanoparticles of diamond with a high refractive index are dispersed, such as "Kaleidoscreen" manufactured by JXTG Energy Co., Ltd. By using the transparent diffusion sheet 55a, it is transparent when no video is being displayed and does not interfere with the driver's view of the scenery outside the vehicle (outside the car). On the other hand, when a video is being displayed, it is possible to diffuse the video light and allow the driver and passengers to view the video information.

[0088] Although the video light from the information display device 48 is S-polarized, a part of the video light scattered inside the aforementioned transparent diffusion sheet 55a has its polarization direction rotated toward the windshield 6, and a part of it becomes close to P-polarized light. Since this light is absorbed by the polarizing plate 55b, it does not reflect on the surface of the windshield 6 that contacts the outside world. Therefore, the video reflected by the film 51 does not become a double image caused by the reflected image of the windshield 6.

[0089] Similarly, it goes without saying that the same effect can be obtained by attaching the aforementioned film 51 to the combiner instead of the windshield 6 as the reflection surface of the video.

[0090] In the information display system and the first information display device of the present invention described above, (1) in a predetermined condition during the day, the P-polarized sunlight component that has passed through the windshield (and then also passes through the combiner in the combiner method) is absorbed in front of the concave mirror so that it does not return to the liquid crystal panel and the polarizing plate. (2) When the first information display device is not used, the concave mirror is rotated by a predetermined angle so that sunlight condensed by the concave mirror does not return to the video display device, thereby preventing the sunlight from returning to the video display device.

[0091] Furthermore, a large high-resolution second information display device is provided at the position of the dashboard corresponding to the video display area in the lower end area of the windshield, and an information video system is provided in which the display video is reflected by the windshield and the reflected image is directly viewed by the driver and passengers. A transparent screen having an effect of scattering video light is provided on the windshield corresponding to the second video display position, and the video can be provided to the driver and passengers with a picture quality at a practically problem-free level by efficiently reflecting it. Since the aforementioned large high-resolution second video display device has high brightness, the video light is prevented from directly entering the eyes of the driver and passengers by controlling the emission direction of the video light.

[0092] According to this embodiment, an information display device that obtains, when a driver drives a vehicle, information by superimposing video information reflected by a windshield on an external landscape viewed through the windshield. The windshield is divided into a plurality of regions, and a large virtual image is displayed in the distance by a head-up display device in a part of the regions. On the other hand, for example, in a region at the lower end of the windshield, the video of a large high-resolution video display device is reflected by the windshield, and the reflected image is directly viewed by the driver or a passenger. As a result, for example, it is possible to obtain high-quality video information capable of corresponding to the high resolution of the display video of an information terminal represented by a smartphone. An in-vehicle information display system and an information display device therefor are provided.

[0093] Furthermore, also in the large high-resolution video display device, the energy of the light incident on the video display device is reduced by absorbing a part of the P-polarized component of light with a wide range of wavelengths as well as mainly the infrared component of sunlight. In addition, a protective cover is provided on the surface of the high-resolution video display device (for example, a liquid crystal display panel), a light absorption layer is provided on one surface to absorb a part of sunlight, and a polarizing plate is provided on the other surface to absorb P-wave sunlight, thereby reducing the adverse effects received by the polarizing plate integrated with the liquid crystal display device (for example, a liquid crystal display panel).

[0094] Also, the video light of the large high-resolution video display device is arranged so as to have directivity and prevent direct light from entering the driver's eyes. The light utilization efficiency can also be increased by making the video light a diverging light beam with directivity.

[0095] Although various embodiments have been described in detail above, however, the present invention is not limited to only the above-described embodiments and includes various modifications. For example, the above-described embodiments describe the entire system in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

Description of Symbols

[0096] 100… Information display device (first information display device), 1… Concave mirror, 2… Lens element, 4… Image display device (liquid crystal display element, liquid crystal display panel), 6… Front glass (projection target member), 7… Housing, V1… Virtual image, 8… Eye point (observer's eye), 101… Light source device, 41… Glare stop, 43… Steering, 47… Dashboard, 48… Information display device (second information display device), 50… Protection cover, 51… Film, 55a… Transparent diffusion sheet, 55b… Polarizing plate, 57… Phase difference plate, 58… Film, 52… Image display element, 59… Black stripe, 1010… Automobile, 300… Smartphone

Claims

1. An information display device that displays video information to a viewer by reflecting video light on a windshield of a vehicle, A backlight device that generates an illumination light beam; a display panel that modulates the illumination light beam from the backlight device in accordance with image information and emits the modulated light beam onto the windshield; a film provided on a portion of the windshield to reflect image light from the display panel toward the viewer's eyes; Equipped with The film has a transparent diffusion sheet and a polarizing plate disposed in this order from the image light incident surface toward the windshield. Information display device.

2. 2. The information display device according to claim 1, The backlight device includes a Fresnel lens in part. Information display device.

3. 2. The information display device according to claim 1, A linear Fresnel lens is included on the light exit surface of the display panel to refract the light beam in a desired direction. Information display device.

4. 2. The information display device according to claim 1, a linear Fresnel lens provided on a light exit surface of the display panel; A protective cover for protecting the linear Fresnel lens; Equipped with The protective cover includes a substantially transparent base material, and a black stripe is provided on a part of the light emission side of the protective cover. Information display device.

5. 5. The information display device according to claim 4, Furthermore, an anti-reflection film is provided between the adjacent black stripes of the protective cover. Information display device.

6. 2. The information display device according to claim 1, A protective cover is provided on the image display surface of the display panel to protect the display panel, and a film that absorbs or reflects the P wave component of the light beam is provided on the light incident side of the protective cover. Information display device.

7. 2. The information display device according to claim 1, The polarizing plate constituting the film transmits S-polarized image light. Information display device.

Images