Information display device

Abstract

This invention provides an information display device with significantly improved resistance to sunlight. The information display device, which displays image information on a projection surface using a virtual image, is characterized by comprising, inside a housing with a partially open portion: an image light generating unit for generating image light for displaying image information; a unit for performing predetermined optical processing on the image light from the image light generating unit; and a unit for projecting the image light from the image light processing unit onto the projection surface through the opening of the housing, enabling an observer to recognize the image information as a virtual image in front of the projection surface. A unit is also provided in the optical path inside the housing to selectively suppress the P-polarization component of light in the visible light region.

Description

[0001] This application is a divisional application of the same invention patent application filed on November 13, 2017, with application number 201780069643.3. Technical Field

[0002] This invention relates to an information display device that projects images onto the windshield or combiner of automobiles, trams, or aircraft (hereinafter collectively referred to as "vehicles"), and to a projection optical system that enables the image to be viewed as a virtual image over the windshield, and to an information display device that uses it. Background Technology

[0003] According to the following patent document 1, a so-called head-up display (HUD) device is known, which projects image light onto the windshield or combiner of a car to form a virtual image, thereby displaying traffic information such as route information and congestion information, as well as vehicle information such as fuel remaining and coolant temperature.

[0004] For this type of information display device, on the one hand, it is desirable to expand the area where the driver can observe the virtual image; on the other hand, high resolution and high recognizability of the virtual image are also important performance factors.

[0005] A head-up display is an optical system that uses a concave mirror (which acts as a convex lens) to provide the driver with a magnified virtual image of the image displayed on the display device. The windshield or superimposed mirror is essential as the final reflective surface.

[0006] As the image display device used in the aforementioned head-up display device, liquid crystal display elements are often used because they are easy to obtain high-quality images and are inexpensive. However, it has become clear that there are new problems. Under specified daytime conditions, sunlight is focused by a concave reflector after passing through the windshield, which damages the liquid crystal panel and polarizer, resulting in a significant reduction in performance.

[0007] The present invention relates to technical means for mitigating the damage caused by sunlight to liquid crystal display elements and polarizers.

[0008] In addition, according to the following Patent Document 2, a head-up display device is known, wherein, in order to reduce the risk of sunlight damaging the liquid crystal display panel, a transmission and reflection component (heat reflector) is provided at a distance from the front side of the liquid crystal display panel in a state that is not parallel to the liquid crystal display panel, so that display light from the liquid crystal display panel can pass through and infrared light is reflected.

[0009] On the other hand, a device has been proposed, such as the one disclosed in Non-Patent Document 1 below, in which the main body, including the combiner, is installed near the roof (sun visor) of a car. However, it has safety issues; for example, in the event of a collision, if the HUD device detaches, there is a possibility of injury to the driver. Therefore, it is considered that, as a head-up display device, the method of directly reflecting image light through the windshield will become the mainstream in the future.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2015-194707

[0013] Patent Document 2: Japanese Patent No. 4788882

[0014] Non-patent literature

[0015] Non-patent literature 1: PIONEER R&D (Vol.22, 2013) Summary of the Invention

[0016] The technical problem that the invention aims to solve

[0017] In the example of the head-up display device disclosed in Patent Document 1, which is prior art, a device for displaying an image and a projection optical system for projecting the image displayed on the display device are provided. The projection optical system has a first reflector and a second reflector in the optical path from the display device to the observer. The structure of the device is realized by satisfying predetermined conditions regarding the incident angle of the image on the first reflector along its major axis, the incident angle of the image on the first reflector along its minor axis, the distance between the image display surface of the display device and the first reflector, and the width of the virtual image perceived by the observer in the horizontal direction. However, Patent Document 1 does not address the new problem of sunlight being focused by the concave reflector after passing through the windshield under the aforementioned predetermined conditions during the day, causing damage to the liquid crystal panel and polarizer, resulting in a significant reduction in performance.

[0018] It can be assumed that the method of using a windshield as a reflective surface as described in the aforementioned Patent Document 1 will become the mainstream in the future. However, this method will be subject to so-called burns (carbonization) due to sunlight passing through the windshield and being focused by the concave reflector under specified daytime conditions. That is, the polarizer and the liquid crystal panel itself located on the light emitting side of the liquid crystal display device will deteriorate due to the heat and light intensity of the focused sunlight, and will be unable to perform their normal functions.

[0019] Similarly, in the technology disclosed in Non-Patent Document 1, where the final reflecting surface is a superimposed mirror, Non-Patent Document 1 did not consider the new problem that, under specified daytime conditions, sunlight is focused by the concave reflector after passing through the windshield and superimposed mirror, causing damage to the liquid crystal panel and polarizer, resulting in a significant reduction in performance.

[0020] Furthermore, in the example of the head-up display device disclosed in the aforementioned Patent Document 1, which is prior art, a device for displaying images and a projection optical system for projecting images displayed on the display device are provided. The projection optical system is constructed by setting a first reflector and a second reflector in the light path from the display device to the observer. No optical element is arranged between the concave reflector and the liquid crystal panel, which is the image display device. Therefore, in addition to the problems mentioned above, the following new problem is not considered: the light that is converged by the concave reflector after passing through the windshield and reflected by the surface of the optical element arranged between the liquid crystal panel and the concave reflector returns to the driver's eyes and overlaps with the virtual image obtained by the image display device, resulting in a significant reduction in the quality of the image observed by the driver, especially the contrast performance and visual resolution.

[0021] Furthermore, the solution proposed in Patent Document 2 is to configure a transmission-reflection component (heat reflector) in the optical path to selectively reflect infrared rays from sunlight in order to reduce the risk of damage to the liquid crystal display panel caused by sunlight. However, the sunlight entering the display contains not only infrared rays but also light from the visible and ultraviolet light regions. To mitigate the damage to the liquid crystal display elements and polarizers caused by sunlight, simply reducing infrared rays is insufficient. That is, Patent Document 2 does not consider the aforementioned adverse effects of external light, including visible light, entering the display—specifically, the significantly reduced quality of the image observed by the driver, especially the contrast performance and visual resolution.

[0022] Therefore, a new problem has been identified: as the image display device used in the aforementioned head-up display device, liquid crystal display elements are often used because they are easy to obtain high-quality images and are inexpensive. However, under specified daytime conditions, sunlight is focused by the concave reflector after passing through the windshield, which damages the liquid crystal panel and polarizer, resulting in a significant reduction in performance.

[0023] Furthermore, a second problem was identified: in order to miniaturize the head-up display, an optical element is placed between the concave mirror and the image display device. The surface reflection of this optical element causes a portion of the sunlight to return to the driver's point of view (eyes), overlapping with the virtual image obtained through the image display device. This results in a significant reduction in the quality of the image observed by the driver, especially the contrast performance and visual resolution.

[0024] The purpose of this invention is to provide an information display device capable of reducing the adverse effects of broadband light contained in external light, including sunlight. Specifically, it can mitigate damage to liquid crystal display elements and polarizers caused primarily by the infrared component of sunlight, and solves the problem that, during the day or at night, certain high-intensity illumination light is reflected back to the driver's eyes from the surface of optical elements disposed between the image display device and the concave mirror forming the information display device, and overlaps with the virtual image obtained through the image display device, thereby causing a significant reduction in the quality of the image observed by the driver, especially the contrast performance and visual resolution.

[0025] Technical solutions for solving the problem

[0026] To achieve the above objectives, the present invention provides, as an example, an information display device that displays image information on a projection surface using a virtual image. The device is characterized by comprising, inside a housing with a partially open portion, an image light generating unit for generating image light for displaying image information; an image light processing unit that performs predetermined optical processing on the image light from the image light generating unit; and a unit that projects the image light from the image light processing unit onto the projection surface through the opening of the housing, enabling an observer to recognize the image information as a virtual image in front of the projection surface. Furthermore, a unit is provided in the optical path inside the housing to selectively suppress the P-polarization component of light in the visible light region.

[0027] More specifically, as will be detailed later, in the information display device of the present invention, in the virtual image optical system from the concave mirror to the image display device (liquid crystal panel):

[0028] (1) An optical unit is provided to prevent sunlight that passes through the windshield and superimposed mirror and is converged by the concave reflector under specified daytime conditions from returning to the liquid crystal panel and polarizer.

[0029] (2) When not using an information display device, the sunlight focused by the concave mirror is prevented from returning to the image display device by rotating the concave mirror by a predetermined angle in a manner that prevents sunlight from returning to the image display device.

[0030] (3) By setting up an optical unit that prevents a portion of sunlight from returning to the driver's viewpoint (eyes), the tolerance to external light, including sunlight, is greatly improved and the reduction in image quality is resolved.

[0031] Invention Effects

[0032] By employing this invention, while miniaturizing the device, an information display device can be provided that reduces the adverse effects of wide-band light contained in external light, including sunlight. Specifically, it can correct the distortion and aberration of the virtual image observed by the driver caused by external light, including sunlight, and at the same time mitigate the following phenomenon: external light, including sunlight, incident through the windshield due to the concave reflector in the virtual image optical system causes damage to the liquid crystal panel and polarizer, which are used as image display devices, resulting in performance degradation. Attached Figure Description

[0033] Figure 1 This is a schematic structural diagram illustrating the peripheral device structure of the information display device in an embodiment.

[0034] Figure 2 This is a top view of a car equipped with an information display device.

[0035] Figure 3 It is a diagram illustrating the differences in the radius of curvature on the windshield.

[0036] Figure 4 It is a schematic diagram showing the information display device, the windshield, and the driver's viewpoint.

[0037] Figure 5 This is a schematic structural diagram showing one embodiment of an information display device, and a light diagram showing the relationship between the virtual image optical system of the information display device in the embodiment and sunlight.

[0038] Figure 6 This is a schematic diagram illustrating the change in glass reflectivity caused by the angle of incidence for S-polarized and P-polarized light.

[0039] Figure 7 This is a diagram illustrating the reflection characteristics of the concave mirror in the embodiment.

[0040] Figure 8 This is a diagram illustrating the reflection characteristics of the concave mirror in the embodiment.

[0041] Figure 9 This is a schematic structural diagram representing an example of an information display device.

[0042] Figure 10 This is a schematic diagram illustrating the structure of the concave reflector in an embodiment.

[0043] Figure 11 This is a schematic diagram illustrating the structure of the concave reflector in an embodiment.

[0044] Figure 12 It is a characteristic diagram representing the spectral irradiance of sunlight.

[0045] Figure 13This is a diagram illustrating the structure of the optical element in an embodiment.

[0046] Figure 14 This is a conceptual diagram illustrating the function of the optical elements in the virtual image optical system of the embodiment.

[0047] Figure 15 This is a conceptual diagram illustrating the function of the optical elements in the virtual image optical system of the embodiment.

[0048] Figure 16 This is a graph showing the transmittance characteristics of an optical element for polarized light.

[0049] Figure 17 It is a structural diagram showing the configuration of the image display device and the light source device.

[0050] Figure 18 It is a schematic structural diagram showing the structure of the light source device.

[0051] Figure 19 It is a schematic structural diagram showing the cross-sectional shape of an optical element used to control the propagation direction of light to the light guide of the light source device.

[0052] Figure 20 This is a schematic structural diagram showing the shape of the polarization conversion section of the light source device.

[0053] Figure 21 This is a schematic diagram illustrating the structure of the synthetic diffusion block in the embodiment.

[0054] Figure 22 This is a structural diagram showing the structure of the light guide of the light source device in the embodiment.

[0055] Figure 23 This is a schematic cross-sectional view showing the structure of the light source device in the embodiment.

[0056] Figure 24 This is a schematic view showing the structure of the light source device in the embodiment.

[0057] Figure 25 This is an explanatory diagram illustrating the polarization transformation technique used in the embodiments.

[0058] Figure 26 This is a schematic diagram illustrating the structure of the information display device in an embodiment.

[0059] Figure 27 This is an explanatory diagram illustrating the principle of obtaining a virtual image using a concave mirror. Detailed Implementation

[0060] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and those skilled in the art can implement various changes and modifications within the scope of the technical concept disclosed in this specification. In all the drawings used to illustrate the present invention, parts with the same function are labeled with the same reference numerals, and sometimes repeated descriptions are omitted.

[0061] <Overview of the Information Display Device>

[0062] Figure 1 This is a schematic structural diagram illustrating the peripheral device structure of an information display device according to an embodiment of the present invention. Here, as an example, an information display device 100 that projects images onto the windshield of a car is specifically described.

[0063] like Figure 1 As shown, the information display device 100 is a device (so-called HUD) that displays various information reflected by the projection component 6 (in this embodiment, the inner surface of the windshield) as a virtual image VI to form a virtual image V1 in front of the vehicle from the driver's line of sight (eyepoint: detailed below) 8. The projection component 6 can be any component on which information can be projected, not only the windshield mentioned above, but also a combiner. That is, the information display device 100 in this embodiment only needs to be able to form a virtual image in front of the vehicle from the driver's line of sight 8 for the driver to observe. The information that can be displayed as a virtual image naturally includes, for example, vehicle information and foreground information captured by a camera (not shown) such as a surveillance camera or a panoramic monitor.

[0064] The information display device 100 includes an image display device 4, a correction lens element 2, and an optical element (not shown) between the correction lens element 2 and the image display device 4 to prevent sunlight from being focused by the concave reflector 1 and returning to the image display device 4. The image display device 4 projects image light for displaying information, and the lens element 2 is used to correct distortions and aberrations that occur when the image displayed on the image display device 4 is formed as a virtual image using the concave (freeform) reflector 1.

[0065] The information display device 100 includes a control device 40 for controlling the aforementioned image display device 4 and backlight. The optical components, including the aforementioned image display device 4 and backlight, constitute the virtual image optical system described later, including a concave reflector 1 that reflects light. The light reflected from this optical component is reflected by the projection component 6 and then directed to the driver's line of sight 8.

[0066] The aforementioned image display device 4 may be, for example, an LCD (Liquid Crystal Display) with a backlight or a VFD (Vacuum Fluorescent Display) with self-illuminating light.

[0067] Alternatively, instead of the aforementioned image display device 4, an image can be displayed on a screen using a projection device, and the concave reflector 1 can be used to make it a virtual image and reflect it onto the projected component, i.e., the windshield 6 or the superimposed mirror (not shown), so that it is directed to the driver's viewpoint 8.

[0068] Such a screen can be constructed, for example, using a microlens array in which microlenses are arranged in a two-dimensional configuration.

[0069] Here, in order to reduce the distortion of the virtual image, the concave mirror 1 adopts the following shape, wherein, in Figure 1 The upper part (the area below the portion of the windshield 6 where the distance to the driver's viewpoint 8 is relatively short) has a relatively smaller radius of curvature to increase magnification, while the lower part (the area below the portion of the windshield 6 where the distance to the driver's viewpoint 8 is relatively long) has a relatively larger radius of curvature to decrease magnification. Furthermore, by tilting the image display device 4 relative to the optical axis of the concave mirror 1, the distortion itself caused by correcting the aforementioned difference in virtual image magnification is reduced, thereby achieving better correction.

[0070] On the other hand, the windshield of a passenger car is 6... Figure 2 , Figure 3 As shown, the radius of curvature Rv in the vertical direction of the vehicle body is different from the radius of curvature Rh in the horizontal direction, and usually has a relationship of Rh > Rv. Therefore, if the windshield 6 is used as the reflective surface, it constitutes the super-toroidal surface of the concave reflector 1. Thus, in the information display device 100 of this embodiment, the shape of the concave reflector 1 adopts different average radii of curvature in the horizontal and vertical directions to correct the virtual image magnification affected by the shape of the windshield 6, that is, to correct the difference in the radius of curvature in the vertical and horizontal directions of the windshield 6. At this time, regarding the shape of the concave reflector 1, since the shape of a spherical or aspherical surface (represented by Equation 2 described later) that is symmetrical about the optical axis is a function of the distance r from the optical axis, it is impossible to individually control the shape of the horizontal and vertical cross sections of different parts. Therefore, it is preferable to adjust it to a freeform surface represented by Equation 1 described later, which is a function of the coordinates (x, y) of the surface from the optical axis of the reflector surface.

[0071] [Formula 1]

[0072]

[0073] [Equation 2]

[0074]

[0075] Back to Figure 1 Between the image display device 4 and the concave mirror 1, a lens element 2 is further arranged as a transmissive optical component. Thus, by controlling the outgoing direction of the light rays heading towards the concave mirror 1, distortion correction can be performed in a way that matches the shape of the concave mirror 1, and at the same time, aberrations of the virtual image, including astigmatism caused by the difference between the horizontal and vertical radii of curvature of the windshield 6, can be corrected.

[0076] To further improve aberration correction capability, the lens element 2 can be a multi-lens system. Alternatively, a curved (freeform) reflector can be used instead of the lens element 2 to control the incident position of light on the concave reflector 1 while reflecting the light path, thereby reducing distortion. As described above, even if an optical element optimally designed to improve aberration correction capability is further configured between the concave reflector 1 and the image display device 4, it does not depart from the technical concept or scope of the present invention. Furthermore, by changing the thickness of the lens element 2 along its optical axis, in addition to the original aberration correction, the optical distance between the concave reflector 1 and the image display device 4 can also be changed, allowing the display position of the virtual image to continuously change from a distance to a closer distance.

[0077] Alternatively, the image display device 4 can be configured to be tilted relative to the optical axis normal of the concave mirror 1 to correct the magnification difference in the vertical direction of the virtual image.

[0078] In addition, an optical element (not shown) can be provided between the concave reflector 1 and the image display device 4 to reflect or absorb sunlight that passes through the windshield and is focused by the concave reflector 1, thereby reducing the amount of light returning to the image display device 4.

[0079] On the other hand, as a major cause of image quality degradation in the information display device 100, it is known that image light emitted from the image display device 4 towards the concave reflector 1 is reflected back to the image display device 4 by the surface of the lens element 2 disposed along the path, and is reflected again on the image display device 4 and superimposed with the original image light, resulting in image quality degradation. Therefore, in this embodiment, it is preferable not only to form an anti-reflective film on the surface of the lens element 2 to suppress reflection, but also to restrict the surface shape of the lens element 2, designing it such that the shape of one or both of the image light incident surface and the exit surface of the lens element 2 is a shape that will not cause the reflected light to be focused on a part of the image display device 4 (for example, a shape with a concave surface facing the image display device 4).

[0080] In addition, the inventors studied the characteristics of the anti-reflective film applied to the surface of the lens element 2. The results, obtained through experiments, showed that by suppressing the reflectivity of the green band (which has the highest visual sensitivity) to below 0.2%, the reflectivity of the red band to below 0.6%, and the reflectivity of the blue band to below 1.0%, even if sunlight reflects off the surface of the optical element, it will not affect the image quality of the virtual image.

[0081] On the other hand, as an image display device 4, if a second polarizer is disposed separately from the liquid crystal panel in order to absorb reflected light from the lens element 2, in addition to the first polarizer disposed close to the liquid crystal panel, it can not only reduce the degradation of image quality, but also reduce the amount of light by absorbing or reflecting sunlight that passes through the windshield and is converged by the concave reflector 1 and incident on the liquid crystal panel, thereby improving the reliability of the liquid crystal panel.

[0082] Furthermore, as the image display device 4, if a second polarizer is disposed separately from the liquid crystal panel in order to absorb reflected light from the lens element 2, in addition to the first polarizer disposed close to the liquid crystal panel, the degradation of image quality can be mitigated. Additionally, by controlling the backlight of the liquid crystal panel, the incident direction of the light incident on the liquid crystal panel is efficiently directed to the entrance pupil of the concave reflector 1. At this time, by reducing the divergence angle of the beam incident on the liquid crystal panel, not only can the image light be efficiently directed to the driver's viewpoint, but also a high-contrast and highly recognizable image can be obtained. The contrast performance of the image corresponding to the divergence angle is more significant in the horizontal direction, and excellent characteristics can be obtained within ±20 degrees. To further improve the contrast performance, a beam within ±10 degrees can be used.

[0083] As the light source device 10, a solid-state light source with a long product life is preferred, and an LED (Light Emitting Diode) with small changes in light output caused by ambient temperature fluctuations is even more preferred. Polarization conversion is performed using a PBS (Polarizing Beam Splitter) equipped with an optical unit that reduces the divergence angle of the light.

[0084] Polarizers are disposed on the backlight side (light incident surface) and the lens element 2 side (light emitting surface) of the liquid crystal panel to improve the contrast of the image light. As for the polarizer disposed on the backlight side (light incident surface), high contrast can be obtained by using an iodine-based polarizer with a high degree of polarization. On the lens element 2 side (light emitting surface), high reliability can be achieved even under conditions of external light incidence and high ambient temperature by using a dye-based polarizer.

[0085] When using a liquid crystal panel as an image display device 4, especially when the driver is wearing polarized sunglasses, there may be a problem where specific polarized light is blocked, making it impossible to see the image. To prevent this problem, it is preferable to place a λ / 4 waveplate on the optical element side of the polarizer disposed on the lens element 2 side of the liquid crystal panel to convert the image light uniformly polarized in a specific polarization direction into circularly polarized light.

[0086] The control device 40 obtains various information from the navigation system 61 as foreground information (i.e., information to be displayed in front of the vehicle using the aforementioned virtual image). This information includes the speed limit and number of lanes of the road corresponding to the current position of the vehicle, the predetermined movement path of the vehicle set in the navigation system 61, and so on.

[0087] The driver assistance ECU 62 is a control device that controls the drive system and control system based on obstacles detected by the surrounding monitoring device 63, thereby realizing driver assistance control. The driver assistance control includes known technologies such as cruise control, adaptive cruise control, pre-collision safety, and lane keeping assist.

[0088] The surrounding monitoring device 63 is a device that monitors the conditions around the vehicle. For example, it may be a camera that detects objects around the vehicle based on images captured around the vehicle, or a detection device that detects objects around the vehicle based on the results of transmitting and receiving probe waves.

[0089] The control device 40 acquires information from the driver assistance ECU 62 (e.g., distance to the vehicle ahead, position of the vehicle ahead, location of obstacles and signs, etc.) as foreground information. Furthermore, the ignition (IG) signal and vehicle status information are also input to the control device 40. This vehicle status information is obtained as vehicle information, such as warning messages indicating a pre-defined abnormal state, including the remaining fuel level in the internal combustion engine and the temperature of the coolant. It also includes the operation results of the turn signals and vehicle speed, gear information, etc. The control device 40 described above is activated when the ignition signal is input. This concludes the description of the entire information display device system of this embodiment.

[0090] <Principles of Sunlight Entry and Suppression Inside the Device>

[0091] Next, I will explain how sunlight enters the aforementioned information display device located in the driver's seat of the vehicle.

[0092] Figure 4The information display device 100, indicating the status near the driver's seat, is located below the windshield 6, for example, on the back side of the instrument panel containing gauges such as the speedometer 42 (on the side of the rear hood). The windshield 6 is mounted between the hood 44 and the roof panel 45, which constitute the vehicle body. Additionally, in this figure, the sun 50, representing daytime, is shown above the vehicle, along with the steering wheel 43 and the driver's (observer's) eyes 8. Figure 5 The sun 50, windshield 6, and observer's eye 8 are specifically selected from the above states and illustrated.

[0093] The intense light from the sun at 50 degrees Figure 4 and Figure 5 As indicated by the hollow arrow, light incident at an angle θ1 relative to the vehicle's windshield 6 is partially reflected by the windshield 6, and the remaining light enters the interior of the information display device 100 through the opening 41 located at the top of the device. At this time, according to... Figure 5 It can be clearly stated that, especially at incident angles greater than 50 degrees, most of the S-polarized component of sunlight (S-rays) is like... Figure 6 As shown, reflection occurs on the aforementioned windshield 6. As a result, most of the sunlight entering the information display device 100 is P-polarized (P-light).

[0094] On the other hand, the image light emitted from the information display device 100, such as Figure 4 and Figure 5 As indicated by the solid line arrow, the light is reflected from the aforementioned windshield 6 or superimposed mirror (not shown) and enters the observer's eye 8.

[0095] More specifically, natural light such as sunlight exists in a state where it is a mixture of P-polarized and S-polarized light. As mentioned above, in areas on the windshield 6 where the angle of incidence exceeds 50 degrees, such as... Figure 6 As shown, the reflectivity on the glass surface varies depending on whether the light is S-polarized or P-polarized, and also depends on the angle of incidence.

[0096] Therefore, in this embodiment, based on the inventor's above-mentioned idea, considering that most of the sunlight entering through the windshield 6 is P-polarized, it can be confirmed that, in order to suppress external light, including sunlight, entering the information display device 100, it is particularly effective to reduce the P-polarized component, while using the S-polarized component as image light projected from the information display device 100 is effective.

[0097] <Specific Embodiments of the Information Display Device>

[0098] The following describes a more specific optical structure of the information display device 100 constructed based on the above ideas.

[0099] Figure 9 The overall structure of the information display device 100, as described above, includes, from the downstream side, a concave reflector 1 for projecting image light that forms a virtual image through the windshield 6, a lens element (lens group) 2 for correcting distortions and aberrations generated at this time, an image display device 4, and a light source device 10 constituting a backlight. Furthermore, to suppress the P-ray component of sunlight entering the information display device 100, as an example, an optical unit 3 for suppressing the P-ray component is provided between the lens element 2 and the image display device 4.

[0100] Firstly, in this embodiment, the concave reflector 1 that projects image light preferably has the function of reflecting visible light (wavelength approximately 400–700 nm) while, in particular, removing unwanted and potentially damaging infrared (IR) and ultraviolet (UV) rays from sunlight, which contains various wavelengths. In this case, by achieving a visible light reflectance of 95% or higher, a virtual image optical system with high light utilization efficiency can be realized.

[0101] Conversely, when the concave reflector 1 is viewed directly through the windshield 6, external light is reflected, causing glare and lowering the car's perceived quality. Furthermore, strong light from sunlight or headlights at night is reflected off the concave reflector 1, with some light returning to the liquid crystal panel, resulting in a decrease in the image quality (e.g., contrast performance) of the image (virtual image) displayed as an information display device. This can also damage the polarizer and the liquid crystal panel. Therefore, by intentionally reducing the reflectivity of the concave reflector 1 to 90% or less, preferably 85% or less, the above problems can be solved.

[0102] In this embodiment, as Figure 10 As shown, a reflective film 1b is provided on the surface of the substrate 1a of the concave reflector 1 (such as a plastic film), which transmits infrared and ultraviolet light and reflects visible light (wavelength approximately 400–700 nm). By providing a protective film 1c on the air side of the reflective film, scratch resistance can be improved. The reflective film can also be formed as an optical multilayer film, but by providing an anti-reflective coating on the surface of the aluminum reflective film, an inexpensive, high-reflectivity reflective film can be obtained.

[0103] Regarding the wavelength characteristics of the reflectivity of the aforementioned reflective film with anti-reflection coating, when three anti-reflection coatings are provided, the following can be obtained: Figure 7 The reflection characteristics are shown. For light with a large incident angle, the reflectivity of P-polarized light can also be reduced, as can the reflectivity of light in the ultraviolet region below 400 nm and the near-infrared region above 700 nm.

[0104] The wavelength characteristics of the reflectivity of a reflective film with five anti-reflection layers can be obtained. Figure 8The reflection characteristics are shown. For light with a large incident angle, the reflectivity of P-polarized light can also be reduced. At the same time, the reflectivity of light in the ultraviolet region below 400 nm and the near-infrared region above 700 nm can also be reduced. Moreover, it can also make the reflection characteristics of the visible light region (wavelength about 400-700 nm) more flat.

[0105] The substrate 1a of the concave reflector is made of a highly transparent material so that the substrate does not absorb the unreflected wavelength components of sunlight. Highly transparent plastic substrates include (1) ZEONEX from Zeon Corporation of Japan, (2) polycarbonate, and (3) acrylic resin. Among these, (1) ZEONEX, with approximately 0% water absorption and a high heat distortion temperature, is most suitable. However, due to its high price, polycarbonate with the same heat distortion temperature but a water absorption rate of approximately 0.2% can be used. Acrylic resin, which has the best formability and lowest price, has the highest moisture absorption rate, therefore a moisture-proof film and a reflective film must be applied.

[0106] To prevent the substrate 1a of the concave mirror from absorbing moisture, such as Figure 11 As shown, along with the reflective film formed on the reflective surface, a SiN (silicon nitride) film can also be formed on the opposite side as a moisture-proof film 1d. The SiN film, as a moisture-proof film, allows sunlight to pass through, thus preventing light absorption within the substrate and suppressing thermal deformation. As a result, even for the concave reflector 1 formed of polycarbonate or acrylic resin, shape changes due to moisture absorption can be prevented.

[0107] To prevent sunlight from being scattered inside the information display device after passing through the concave reflector 1 using the aforementioned technology, it is possible to... Figure 11 The concave mirror shown has a light-absorbing material forming a retaining part (not shown) on its back side, which also dissipates heat.

[0108] In addition to the concave reflector 1 that has the function of suppressing / removing infrared and ultraviolet light as described above, or as an alternative, a light-transmitting plate that has the function of removing infrared and ultraviolet light may be provided in the opening 41 formed on the upper part of the information display device 100, although it is not shown here. Furthermore, in addition to suppressing infrared and ultraviolet light, this light-transmitting plate can also prevent external dust from entering the interior of the information display device 100.

[0109] In this way, by using the concave reflector 1 described above, it is possible to remove unwanted components from sunlight containing a large number of spectral components that enters the information display device 100 through the opening 41, and to selectively extract mainly the visible light components (see reference). Figure 12 ).

[0110] Next, for one example of optical unit 3 used to suppress the P-component of sunlight centered on the aforementioned visible light component, refer to... Figure 13 and Figure 14 Please provide an explanation.

[0111] Figure 13 The diagram shows the magnified cross-section of optical unit 3a, which combines two optical elements and has a PBS (Polarizing Beam Splitter) at their junction. The two optical elements are optical element 3c with an isosceles triangle cross-section and optical element 3b with a right-angled triangle cross-section. As shown by the arrow in the figure, it has the function of transmitting the S-component of the incident light while simultaneously blocking the P-component (causing it to be reflected laterally).

[0112] in addition, Figure 14 (a) represents the overall structure of optical unit 3f. Figure 14 (b) represents its partially magnified cross-section. In the optical unit 3f, instead of the above structure, two optical elements 3fb and 3fc with right-angled triangular cross-sections are provided between two light-transmitting plate-shaped components 3fa, and at their joint surface, there are... Figure 13 The illustrated embodiment has the same characteristics as the PBS. Polarization separation performance—the ability to separate natural light into P-polarized and S-polarized light—is highest when the tilted surface is at 45 degrees relative to the incident light ray; therefore, it is preferable that the apex angle of the cross-sectional shape of the aforementioned optical element is 90 degrees.

[0113] As another example of optical unit 3 for suppressing the P-component of sunlight centered on the aforementioned visible light component, an optical multilayer film is used instead of the one provided in the above-mentioned optical unit 3. Figure 13 and Figure 14 The PBS in the optical unit shown can also achieve the same effect.

[0114] As described above, the optical unit 3 can transmit the S-ray component of the incident light and block the P-ray component, thus not only suppressing sunlight, but also improving the contrast performance of the liquid crystal panel as an image display device.

[0115] Figure 15 A so-called wire-grid polarizer 3e is used, in which a film with fine metal lines 3i formed in a grid pattern on one surface of a light-transmitting plate-shaped member 3g. Furthermore, by configuring the wire-grid polarizer 3e at a predetermined angle relative to the light, as shown in the figure, it is possible, similarly to the above, to transmit the S-ray component of the incident light while simultaneously blocking the P-ray component (causing it to be reflected laterally), and to reflect the reflected light to the outside of the reflecting surface of the concave (freeform) mirror, thereby not affecting the optical performance of the information display device.

[0116] Head-up displays are achieved using concave mirrors, and the principle behind the generation of virtual images by concave mirrors is as follows: Figure 27 As shown, by placing the object point AB inside the focal point F (focal length f) relative to point O on the optical axis of the concave mirror 1', a virtual image formed by the concave mirror 1' can be obtained. Figure 27 In the diagram, for ease of explanation, the concave mirror 1′ is considered as a convex lens with the same positive optical power, and the object point and the convex lens are represented (for ease of explanation). Figure 27 The relationship between the concave mirror (referred to as a concave mirror) and the generated virtual image.

[0117] To ensure the focusing performance of both the virtual image reflected from the upper part of the windshield and seen by the driver (the image to be superimposed on the distant scenery) and the virtual image reflected from the lower part of the windshield and seen by the driver (the image to be superimposed on the nearby scenery) when the driver observes the virtual image generated by the head-up display, for the image display device ( Figure 27 The optical axis LL′ of the liquid crystal panel (corresponding to AB in this embodiment) and the concave (freeform) reflector can tilt the image display device. This is also to ensure that each virtual image simultaneously satisfies the magnification M = b / a of the virtual images generated by the liquid crystal panel and the concave (freeform) reflector.

[0118] Therefore, as described above, as long as the optical unit 3 (e.g., a wire grid polarizer) is arranged parallel to the image display device, it can return P-light and unwanted sunlight to the concave mirror without compromising polarization characteristics, thus without reducing the image quality (virtual image) of the information display device.

[0119] Figure 16 This illustrates one example of the transmittance of incident light obtained using the aforementioned optical unit 3e. In this curve, the solid line represents the transmittance of S-polarized light from a conventional wire-grid polarizer. The dashed line represents the transmittance of P-polarized light. By making the polarization characteristics of the polarizer comparable to those of existing polarizers, as shown by the dashed line, the inventors were able to improve the light-shielding characteristics (larger spacing) in the ultraviolet (UV) and near-infrared (IR) regions, while by having the transmittance characteristics of P-polarized light shown by the dashed line, they were able to selectively and sufficiently suppress the P-light component from sunlight centered on the visible light component.

[0120] Furthermore, as optical unit 3, in addition to using the aforementioned element that reflects the P-polarized component, the same effect can be achieved by providing a polarization unit that absorbs the P-polarized component of sunlight. At this time, by providing a reflective film that blocks ultraviolet and near-infrared rays on the sunlight-incident side of the substrate that holds and fixes the polarizer, the energy of ultraviolet and near-infrared rays incident on the polarizer and liquid crystal panel can be reduced to mitigate damage. For the image displayed on the liquid crystal panel as an image display device, since the polarization degree of the first polarizer attached to the liquid crystal panel is multiplied by the polarization degree of the absorbing polarizer of optical unit 3, a high-contrast image with high polarization degree can be obtained.

[0121] Furthermore, as can be seen from the above figures, the optical units 3 (3a, 3e) can be plate-shaped, forming a so-called filter-like structure. This is the structure required to achieve miniaturization of the information display device 100, i.e., as described above. Figure 4 , 5 As shown in Figure 9, even in virtual image optical systems where the distance (optical axis) Z for magnifying the image displayed on the image display device 4 using the concave mirror 1 is relatively short, it is highly advantageous to easily arrange the optical unit within the small optical path space of the information display device 100. In particular, the area of ​​the optical unit 3 arranged therein can be reduced within the space between, for example, the lens element 2 and the image display device 4, thus also being advantageous in terms of price.

[0122] By employing the optical structure of the information display device 100 described above, unwanted IR and UV light can be removed from sunlight entering the device through the windshield 6. Furthermore, the optical unit 3 can effectively reduce the p-polarized light component (p-polarized light) from sunlight that enters the information display device 100 through the upper opening 41 and may cause adverse effects such as carbonization to the image display device 4 and surrounding polarizers disposed therein. In other words, it can mitigate damage to the liquid crystal display element and polarizer caused by sunlight and suppress the performance degradation of the information display device 100 caused by sunlight.

[0123] <Light source device for image display>

[0124] As described above, in the optical system of the information display device 100, sunlight entering the device from the outside through the windshield 6 is attenuated by the aforementioned optical unit 3. Simultaneously, the image light used to generate virtual images of various image information displayed in front of the vehicle is as described above. Figure 4 and Figure 5As indicated by the arrow in the solid line, the image light is projected from the information display device 100 and reaches the windshield 6 via the lens element 2 and the concave reflector 1. Furthermore, although the image light also passes through the aforementioned optical unit 3, as described above, this image light utilizes the S-polarized component (s-light).

[0125] Therefore, an example of an image display device 4 and its light source device 10 for generating image light of the S-ray component will be described in detail below.

[0126] exist Figure 17 In the above-mentioned liquid crystal display element, which serves as the image display device 4, the light source device 10 constituting its light source is shown in an unfolded perspective view below it.

[0127] The light source device 10 includes a light source device housing 101, which is formed of, for example, plastic, and houses the LED, collimator, composite diffuser, light guide, etc., which will be described in detail later. Its upper surface is used to mount the liquid crystal display element, which serves as the image display device 4. In addition, an LED (Light Emitting Diode) element, which serves as a semiconductor light source, and an LED substrate 12, which is provided with its control circuit, are mounted on one side of the light source device housing 101, and a heat sink 103 is mounted on the outer side of the LED substrate 102 to cool the heat generated by the LED element and the control circuit.

[0128] On the other hand, the image display device 4 mounted on the upper surface of the light source housing 11 is a liquid crystal display element, including a liquid crystal display panel frame 401, a liquid crystal display panel 402 mounted on the frame, and an FPC (Flexible Printed Circuit) 403 electrically connected to the panel. That is, as described in detail below, the liquid crystal display panel 402, together with the LED element as a solid-state light source, generates and controls the image to be displayed under the control of control signals sent from the control circuit (not shown here) constituting the electronic device.

[0129] Next, with reference to the accompanying drawings, the internal structure of the light source device 10, namely the optical system housed in the light source device housing 101, will be described in detail.

[0130] Figure 18 This indicates that multiple (two in this example) LEDs 14a and 14b (not shown here) constituting the light source are mounted in designated positions relative to the LED collimator 15. The LED collimator 15 is formed of a light-transmitting resin, such as acrylic resin. The LED collimator 15 is as follows... Figure 19As shown, the outer peripheral surface 156 has a convex conical shape obtained by rotating a generally parabolic cross section, and has a recess 153 at its top, with a convex portion (i.e., a convex lens surface) 157 formed in the center of the recess 153. Furthermore, a convex lens surface (or a concave lens surface) 154 protruding outwards is provided in the center of its planar portion. Additionally, the parabolic surface 156 forming the conical outer peripheral surface of the LED collimator 15 is set within an angle range that allows light emitted from the LED 14a in the peripheral direction to undergo total internal reflection within it, or the parabolic surface 156 is formed with a reflective surface.

[0131] On the other hand, LEDs 14a and 14b are respectively disposed at predetermined positions on the surface of their circuit board, namely LED board 102. The LED board 102 is disposed and fixed relative to the LED collimator 15 such that LEDs 14a or 14b on its surface are respectively located at the center of its recess 153.

[0132] Using this structure, and with the aforementioned LED collimator 15, light emitted from LEDs 14a and 14b, especially light emitted upwards (to the right in the figure) from their central portion, is converged into parallel light by the two convex lens surfaces 157 and 154 that form the shape of the LED collimator 15. Furthermore, light emitted from other portions towards the periphery is also reflected by the parabolic surface of the conical outer peripheral surface of the LED collimator 15, similarly converging into parallel light. In other words, by using the LED collimator 15—with its central portion forming a convex lens and its peripheral portion forming a parabolic surface—almost all the light generated by LEDs 14a and 14b can be extracted into parallel light, thereby improving the utilization efficiency of the generated light.

[0133] A polarization conversion element 21, which will be detailed later, is provided on the light-emitting side of the LED collimator 15. For example... Figure 20 As shown, the structure of the polarization conversion element 21 is as follows: a light-transmitting component with a parallelogram cross-section (hereinafter referred to as a parallelogram column) and a light-transmitting component with a triangular cross-section (hereinafter referred to as a triangular column) are combined together, and multiple such components are arranged in parallel and in an array on a surface orthogonal to the optical axis of the parallel light from the LED collimator 15. Furthermore, polarization beam splitter (hereinafter referred to as "PBS") film 211 and reflective film 212 are alternately arranged at the interface between these arrayed adjacent light-transmitting components, and a waveplate 213 with a 1 / 2λ phase is provided on the exit surface of the light incident on the polarization conversion element 21 and transmitted through the PBS film 211.

[0134] The exit surface of the polarization conversion element 21 is also provided with Figure 21The rectangular composite diffuser block 16 is shown. That is, the light emitted from LED 14a or 14b becomes parallel light under the action of LED collimator 15 and is incident on the composite diffuser block 16. After being diffused by the structure 161 on the emission side, it reaches the light guide 17 described later.

[0135] Let's go back to the above. Figure 18 On the exit surface side of the aforementioned composite diffuser block 16, a prism-shaped light guide 17 with a roughly triangular cross-section is disposed across the first diffuser plate 18a, and a second diffuser plate 18b is mounted on its upper surface. Thus, the horizontal light from the collimator 15 is reflected upwards as shown in the figure by the light guide 17 and guided to the incident surface of the liquid crystal display element. Furthermore, the intensity of the incident light is homogenized by the first and second diffuser plates 18a and 18b.

[0136] The details of the light guide 17 described above are explained below with reference to the accompanying drawings. Figure 22 (a) is a three-dimensional view showing the light guide 17 as a whole. Figure 22 (b) is its cross-section. Figure 22 (c) and (d) are enlarged section views showing details of the cross-section.

[0137] The light guide 17 is formed of a light-transmitting resin, such as acrylic resin, with a roughly triangular cross-section (see reference). Figure 22 (b)) the rod-shaped component, and, as according to Figure 22 As can be clearly seen in (a), it includes a light guide light incident portion (surface) 171 that faces the emission surface of the composite diffuser block 16 across the first diffuser plate 18a, a light guide light reflecting portion (surface) 172 that is formed as an inclined surface, and a light guide light emitting portion (surface) 173 that faces the liquid crystal display panel 402 of the liquid crystal display element across the second diffuser plate 18b.

[0138] In the light guide light reflecting portion (surface) 172 of the light guide 17, such as Figure 22 As shown in the enlarged views of (c) and (d), numerous reflecting surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape. Furthermore, the reflecting surface 172a (the line segment sloping upwards to the right in the figure) forms an αn (where n is a natural number, for example, 1 to 130 in this case) with the horizontal plane represented by the dotted line in the figure. As an example, αn is set to less than 43 degrees (more than 0 degrees) here.

[0139] On the other hand, the connecting surface 172b (the line segment tilted downwards to the right in the figure) forms a βn (n is a natural number, for example, 1 to 130 in this example) relative to the reflecting surface. That is, the connecting surface 172b of the reflecting part is tilted at an angle such that, at this angle, the connecting surface 172b is located within the shadow of the incident light in the range of the half-value angle of the scatterer described later. α1, α2, α3, α4... form the elevation angle of the reflecting surface, and β1, β2, β3, β4... form the relative angle between the reflecting surface and the connecting surface, which, as an example, is set to 90 degrees or more (less than 180 degrees), and these will be detailed later. Furthermore, in this example, β1 = β2 = β3 = β4 = ... = β2 = ... β130.

[0140] For ease of explanation, Figure 23 and Figure 24 This is a schematic diagram showing the relatively enlarged sizes of the reflecting surface 172a and the connecting surface 172b within the light guide 17. In the light guide incident portion (surface) 171 of the light guide 17, the main light ray is deflected by δ in the direction that increases the incident angle onto the reflecting surface 172a (refer to...). Figure 24 (b) That is, the light guide incident portion (surface) 171 is formed into a curved convex shape that is inclined toward the light source side. Accordingly, parallel light from the exit surface of the composite diffuser block 16 is diffused and incident through the first diffuser plate 18a, as shown in the figure. Under the action of the light guide incident portion (surface) 171, it is slightly bent (deflected) upward and reaches the light guide light reflecting portion (surface) 172.

[0141] On the light-reflecting portion (surface) 172 of the light guide, a large number of reflective surfaces 172a and connecting surfaces 172b are alternately formed in a sawtooth shape. The diffused light undergoes total internal reflection on each reflective surface 172a, and then passes upward through the light-emitting portion (surface) 173 of the light guide and... Figure 4 The second diffuser plate 18b shown is incident as parallel diffused light onto the liquid crystal display panel 402 of the liquid crystal display element 50. Therefore, the elevation angles α1, α2, α3, α4... of the reflective surfaces are set such that each reflective surface 172a is at least a critical angle relative to the diffused light. On the other hand, the relative angles β1, β2, β3, β4... between the reflective surface 172a and the connecting surface 172b are set to a certain angle as described above, preferably an angle of 90 degrees or more (βn ≥ 90°), the reason for which will be explained later.

[0142] With the above structure, each reflective surface 172a is always at an angle greater than or equal to the diffused light. Therefore, even without forming a reflective film such as metal in the reflective part 172, total internal reflection can occur, enabling a low-cost light source device.

[0143] The elevation angles α1, α2, α3, α4... of the reflecting surface gradually increase from the lower part to the upper part of the light reflecting section (surface) 172 of the light guide. This is because, since the light passing through the liquid crystal display panel 402 of the liquid crystal display element has a certain degree of divergence angle, it is particularly important to prevent a portion of the light passing through the peripheral part of the liquid crystal display panel 52 from becoming darker at the periphery of the downstream reflector, thus preventing the formation of so-called vignetting (edge ​​dimming). Figure 23 As shown in the light ray 30, a structure is adopted that slightly deflects the light rays from the periphery toward the central axis.

[0144] Figure 23 In the equation, Lr1, Lr2, Lr3, Lr4... represent the projected lengths of the reflective surface 172a on the horizontal plane, and Lc1, Lc2, Lc3, Lc4... represent the projected lengths of the connecting surface 172b on the horizontal plane. The ratio Lr / Lc, i.e., the ratio of the reflective surface 172a to the connecting surface 172b, can change with position. The intensity distribution of the main ray 30 incident on the light guide 17 may not be consistent with the desired intensity distribution within the incident surface of the liquid crystal display panel. Therefore, the intensity distribution is adjusted using the ratio Lr / Lc of the reflective surface 172a to the connecting surface 172b. The higher this ratio, the higher the average intensity of the reflected light in that portion. Typically, the intensity of the ray 30 incident on the light guide tends to be stronger in the central part; therefore, to correct this situation, the ratio Lr / Lc varies with position, especially decreasing in the central part. Because of the aforementioned structure where the ratio Lr / Lc varies with position and the aforementioned structure where the elevation angles α1, α2, α3, α4... of the reflecting surface vary with position, the envelope 172c representing the approximate shape of the reflecting part 172 is as follows: Figure 23 The figure shown is in a curved shape.

[0145] Furthermore, the value is set as Lr1+Lc1=Lr2+Lc2=Lr3+Lc3=Lr4+Lc4……=Lr+Lc≤0.6mm. By employing this structure, the repeating spacing of the reflective surfaces seen from the light-emitting surface 173 of the light guide 17 is made uniform. Since this spacing is less than 0.6mm, combined with the function and effect of the diffuser plates 18a and 18b, when viewed through the liquid crystal display panel 402, each emitting surface appears as a continuous surface rather than a separate one. Therefore, uniformity of spatial brightness through the liquid crystal display panel 402 can be achieved, thereby improving display characteristics. In other words, this structure can achieve uniform distribution of incident light intensity on the liquid crystal display panel 402. On the other hand, if the value of Lr+Lc is less than 0.2mm, it not only consumes processing time but also makes it difficult to perform high-precision processing on each reflective surface 172a; therefore, a value of 0.2mm or greater is preferred.

[0146] By adopting the shape of the light-reflecting portion (surface) 172 of the light guide 17 described above, the conditions for total internal reflection of the main light can be met. It eliminates the need for a reflective film such as aluminum on the reflective portion 172, effectively reflecting light and eliminating the need for aluminum thin film evaporation, which increases manufacturing costs. This allows for the realization of a bright S-polarized light source at a lower cost. Furthermore, by setting each relative angle β such that the connecting surface 172b is located within the shadow of the main ray 30 diffused by the composite scattering block 16 and the diffuser plate 18a, unwanted light incident on the connecting surface 172b is suppressed, thereby reducing unwanted light reflection and achieving a light source device with excellent characteristics.

[0147] Furthermore, by employing the aforementioned light guide 17, and especially by appropriately setting the elevation angles α1, α2, α3, α4... of the reflecting surface, the length of the light emitting surface 173 along the optical axis can be freely changed. Therefore, a light source device can be realized in which the size (surface dimension) of the light emitting surface 173 can be changed to a suitable and required size (surface dimension) for devices such as the aforementioned liquid crystal display panel 402, relative to the light guide incident portion (surface) 171. This means that the light emitting surface 173 can be made to a desired size regardless of the arrangement shape of the LEDs 14a and 14b constituting the light source, thereby obtaining a surface-shaped light source of the desired size. Furthermore, it ensures design freedom, including the arrangement of the LEDs 14a and 14b constituting the light source, which is also advantageous in terms of overall device miniaturization.

[0148] Moreover, such as Figure 25 As shown, instead of the usual transparent resin, a polarization conversion element can be used to construct a light guide 17 (light guide 17′) disposed behind the synthetic diffuser block 16. In this structure, as can be clearly seen from the figure, the transparent component 211′ of the triangular prism and the transparent component 212′ of the parallelogram prism are combined together, and a PBS film 211 is formed on their boundary surface. A 1 / 2λ phase plate 213 is formed on the upper surface of the transparent component 212′ of the parallelogram prism, and a reflective film 212 is formed on its side. The PBS film 211 reflects the S-polarized light (see the (×) mark in the figure) in the incident light emitted from the LED 14 and becoming parallel light after passing through the LED collimator 15, and transmits the P-polarized light (see the up and down arrows in the figure).

[0149] With the above structure, as clearly shown in the figure, the incident light emitted from LED 14 and becoming parallel light after passing through LED collimator 15 is emitted upward as S-polarized light from the upper surface of light guide 17′, which is composed of a polarization conversion element instead of light guide 17. That is, in the above structure, especially by eliminating the light guide 17, which is usually made of light-transmitting resin, the device can be significantly miniaturized, and the manufacturing cost of the device can be reduced.

[0150] That is, by using the aforementioned light source device 10 as the light source device for the image display device 4, i.e., the liquid crystal display element, a small and highly efficient modular S-polarized light source device can be achieved with fewer light sources (number of LEDs, power consumption). Moreover, unwanted IR and UV light can be removed by utilizing the aforementioned concave reflector 1 and optical unit 3, and the P-light component (p-polarized light) that can cause adverse effects such as carbonization on the image display device 4 and surrounding polarizers can be effectively reduced, mitigating damage caused by sunlight. Furthermore, by utilizing the S-light component (s-polarized light), an information display device 100 that can display better information can be achieved.

[0151] As detailed above, the information display device 100 of the present invention can further improve light utilization efficiency and uniform illumination characteristics, while enabling small-scale and low-cost manufacturing, including a modular S-polarized light source device. Furthermore, while the above description illustrates the case where the polarization conversion element 21 is mounted after the LED collimator 15, the present invention is not limited thereto. The same effect can be achieved by placing it in the optical path before the liquid crystal display element, a fact readily apparent to those skilled in the art.

[0152] <Other Structures>

[0153] The information display device 100 described above can remove unwanted IR and UV light from sunlight during its operation using the concave reflector 1 and optical unit 3. However, the information display device 100 does not need to operate, for example, when the vehicle is parked in a parking lot and the engine key is off. Therefore, in this state, it is preferable to block the sunlight entering through the normal light path, that is, to block the light path that enters the information display device 100 through the upper opening 41 and reaches the image display device 4 and its surrounding polarizers.

[0154] As an example, Figure 26 This is a perspective view of the information display device 100 as seen from the rear side, with all components disassembled. Figure 26As shown, for the concave reflector 1, which is rotatably mounted inside its housing, i.e., the outer casings 51 and 55, a concave reflector drive unit 42, composed of a motor for adjusting its position, moves the concave reflector 1 to a predetermined position. At this predetermined position, the concave reflector 1 reflects incoming sunlight in a direction that cannot reach the image display device 4 (a direction different from the normal light path). The operation of the concave reflector drive unit 42 is achieved by the aforementioned... Figure 1 The CPU 35 shown can easily implement this by executing software pre-stored in the ROM 34. Accordingly, especially in situations where the incoming sunlight is a problem, such as when a vehicle is stopped, by changing the light path of the incoming light in the opposite direction, even under the strong sunlight of midsummer, it is possible to reliably prevent sunlight from damaging or deteriorating the optical components of the information display device, namely the image display device 4 and the surrounding polarizer, and thus the light source device 10.

[0155] That is, an information display device can be provided that, when the information display device is not in use, prevents sunlight converged by the concave reflector from returning to the image display device by rotating the concave reflector by a predetermined angle in a manner that prevents sunlight from returning to the image display device, thereby significantly improving its resistance to sunlight.

[0156] Various embodiments have been described in detail above, but the present invention is not limited to the above embodiments and includes various modifications. For example, the above embodiments have described the entire system in detail for ease of understanding of the present invention, but are not limited to having all the structures described. In addition, a part of the structure of one embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added to the structure of one embodiment. Furthermore, for a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0157] Explanation of reference numerals in the attached figures

[0158] 100……Information display device, 1……Concave mirror, 2……Lens element, 3, 3a, 3e, 3f……P-light component suppression optical unit (element), 4……Image display device (liquid crystal display element, liquid crystal display panel), 6……Projected component (windshield), 7……Housing, V1……Virtual image, 8……Viewpoint (observer's eye), 10……Light source device, 41……Opening.

Claims

1. An information display device that displays image information as a virtual image on a projection surface, characterized in that, An image light generating section for generating image light is mounted in a housing having an opening section; A lens element that performs a prescribed optical process on image light that exits from the image light generating section; and A projection section that projects image light that exits from the lens element toward the front of the projection surface via the opening section, wherein an optical section that suppresses the P-polarization component of light in the visible light region is provided between the lens element and the image light generating section, The optical section includes: a first optical element having an isosceles triangular cross section; a second optical element having a right triangular cross section; and a polarization separation member located on a face of the first optical element and the second optical element that are in contact.

2. The information display device according to claim 1, wherein: a unit that suppresses at least one or both of light in the infrared region and light in the ultraviolet region is provided on an optical path inside the housing.

3. The information display device according to claim 1, wherein: the image light generating section includes a light source device, the light source device has a collimator having an outer peripheral surface in the shape of a convex circular cone obtained by rotating a cross section of a substantially parabola, a reflection surface is formed on an inner surface of the parabolic surface that forms the outer peripheral surface.

4. The information display device according to claim 3, wherein: a recess is provided in the center of the top of the collimator, and a convex lens surface is formed in the recess, a convex lens surface is provided in the center of a planar section formed on the top of the collimator.

5. The information display device according to claim 3, wherein: the collimator has a polarization conversion element on the light exit side of the collimator, a rectangular synthetic diffusion block is provided on the exit surface of the polarization conversion element, a light guide body that guides light to the image light generating section is provided behind the synthetic diffusion block, light that exits from the light source of the light source device is incident on the synthetic diffusion block and is incident on the light guide body after being diffused. An image light generating section for generating image light is mounted in a housing having an opening section; 6. An information display device that displays image information as a virtual image on a projection surface, characterized in that, A lens element that performs a prescribed optical process on image light that exits from the image light generating section; and A projection section that projects image light that exits from the lens element toward the front of the projection surface via the opening section, wherein an optical section that suppresses the P-polarization component of light in the visible light region is provided between the lens element and the image light generating section, The optical section includes: a plurality of plate-shaped members having light transmission properties; optical elements having a right triangular cross section located between the plate-shaped members; and a polarization separation member located on a face of the optical elements and the plate-shaped members that are not in contact.

7. The information display device according to claim 6, wherein: a unit that suppresses at least one or both of light in the infrared region and light in the ultraviolet region is provided on an optical path inside the housing.

8. The information display device according to claim 6, wherein: the image light generating section includes a light source device, ​ ​ The light source device has a collimator having an outer peripheral surface of a convex conical shape obtained by rotating a substantially parabolic cross section, A reflection surface is formed on an inner surface of a parabolic surface forming the outer peripheral surface.

9. The information display device according to claim 8, wherein: a concave portion is provided in the center of the top of the collimator, and a convex lens surface is formed in the concave portion, a convex lens surface is formed in the center of a planar portion formed in the top of the collimator.

10. The information display device according to claim 8, wherein: the collimator has a polarization conversion element on the light exit side of the collimator, a rectangular synthetic diffusion block is provided on the exit surface of the polarization conversion element, a light guide body that guides light to the image light generating portion is provided behind the synthetic diffusion block, light emitted from the light source of the light source device is incident on the synthetic diffusion block and is incident on the light guide body after being diffused.

11. An information display device that displays image information as a virtual image on a projection surface, characterized in that, including: an image light generating portion that is mounted in a housing having an opening portion, for generating image light; a lens element that performs a prescribed optical process on image light emitted from the image light generating portion; and a projection portion that projects image light emitted from the lens element to the front of the projection surface via the opening portion, wherein an optical portion that suppresses a P-polarization component of light in the visible light region is provided between the lens element and the image light generating portion, the optical portion includes: a first optical element having an isosceles triangular cross section; a second optical element having a right-angled triangular cross section; and an optical multilayer film that is located on a surface of the first optical element that is in contact with the second optical element.

12. The information display device according to claim 11, wherein: a unit that suppresses at least one or both of light in the infrared region and light in the ultraviolet region is provided on an optical path inside the housing.

13. The information display device according to claim 11, wherein: the image light generating portion includes a light source device, the light source device has a collimator having an outer peripheral surface of a convex conical shape obtained by rotating a substantially parabolic cross section, a reflection surface is formed on an inner surface of a parabolic surface forming the outer peripheral surface.

14. The information display device according to claim 13, wherein: a concave portion is provided in the center of the top of the collimator, and a convex lens surface is formed in the concave portion, a convex lens surface is formed in the center of a planar portion formed in the top of the collimator.

15. The information display device according to claim 13, wherein: the collimator has a polarization conversion element on the light exit side of the collimator, a rectangular synthetic diffusion block is provided on the exit surface of the polarization conversion element, a light guide body that guides light to the image light generating portion is provided behind the synthetic diffusion block, light emitted from the light source of the light source device is incident on the synthetic diffusion block and is incident on the light guide body after being diffused. including:

16. An information display device for displaying image information as a virtual image on a projection surface, characterized by comprising: an image light generating portion that is mounted in a housing having an opening portion, for generating image light; a lens element that performs a prescribed optical process on image light emitted from the image light generating portion; and a projection portion that projects image light emitted from the lens element to the front of the projection surface via the opening portion, ​ a projection section that projects the image light emitted from the lens element to the front of the projection surface via the opening section, wherein an optical section that suppresses a P-polarization component of light in a visible light region is provided between the lens element and the image light generating section, the optical section includes: a plurality of plate-like members having light transmissivity; an optical element having a right triangle cross section between the plate-like members; and an optical multilayer film on a surface of the optical element that does not contact the plate-like members.

17. The information display device according to claim 16, wherein: a unit that suppresses at least one or both of light in an infrared region and light in an ultraviolet region is provided on an optical path inside the housing.

18. The information display device according to claim 16, wherein: the image light generating section includes a light source device, the light source device has a collimator having an outer peripheral surface of a convex conical shape obtained by rotating a cross section of a substantially parabola, a reflection surface is formed on an inner surface of a parabolic surface that forms the outer peripheral surface.

19. The information display device according to claim 18, wherein: a recess is provided in the center of a top portion of the collimator, and a convex lens surface is formed in the recess, a convex lens surface is provided in the center of a flat surface portion formed in the top portion of the collimator.

20. The information display device according to claim 18, wherein: the collimator has a polarization conversion element on a light exit side of the collimator, a rectangular synthetic diffusion block is provided on an exit surface of the polarization conversion element, a light guide body that guides light to the image light generating section is provided behind the synthetic diffusion block, light emitted from a light source of the light source device is incident on the synthetic diffusion block and is incident on the light guide body after being diffused.

Images