Vehicle-mounted information display system with solid light source

Abstract

Provided is a vehicle-mounted information display system having a solid-state light source, the information system having a virtual image type image display device, the display device being provided with an optical system including an image display device that displays an image, and a light source that supplies light to the image display device. A light source device having a surface-emitting solid light source; and an optical module for receiving image light from the image display device. According to the light source device, a single light source module is formed by the surface light-emitting solid light source and the optical element for narrowing the divergence angle of the divergent light beam emitted by the surface light-emitting solid light source, and a plurality of single light source modules are arranged in a two-dimensional mode to form the light source unit and the image display device. The light beam from the light source unit is incident on an image display device, the intensity of the light is adjusted according to an image signal through the image display device, and an image is displayed on a screen. The performance of the optical assembly is improved by considering the diffusion characteristic of the image light emitted by the image display device.

Description

Technical Field

[0001] The present invention relates to the technical field of projecting images onto the front windshield or combination screen of transportation vehicles such as cars, trains, and airplanes (hereinafter collectively referred to as "vehicles"), and in particular to an in-vehicle information display system with a solid light source. Background Art

[0002] A known head-up display device (HUD) for a vehicle uses a concave mirror to magnify the image from an image source and present it to the driver through the front windshield. The light emitted by the image source used in this information display device is completely diffuse. To ensure sufficient brightness of the magnified image in a projection optical system using a concave mirror, a large concave mirror is required to capture the widely diverging image beam.

[0003] In optical systems that use concave mirrors to magnify the image displayed by an image source and produce a virtual image, conventional image sources, such as organic EL (Electric Luminescent), emit completely diffuse image light. Therefore, large-diameter concave mirrors are required to capture all of the image light. Furthermore, to achieve large apertures and good focusing performance in virtual image optical components using concave mirrors, multiple concave mirrors or a combination of lens elements are required.

[0004] However, in the design of optical components for obtaining a virtual magnified image using a concave mirror according to the above-mentioned conventional technology, the diffusion characteristics and directional characteristics of the image light emitted by the image source, as well as the construction and implementation technology of the optimal optical system including these characteristics, are not taken into consideration. Summary of the Invention

[0005] To address the above-mentioned issues, the present invention aims to provide an optical assembly structure and implementation technology that improves light utilization efficiency. In this optical assembly, which uses a concave mirror to produce a magnified virtual image, light utilization efficiency is improved by optimizing the emission direction and diffusion characteristics of image light emitted by an image source, without increasing the aperture or number of lenses in the optical assembly.

[0006] To achieve the above-mentioned objectives, the present invention adopts a technical solution: an in-vehicle information display system having a solid-state light source, comprising a virtual image display device, wherein the virtual image display device comprises an optical system, the optical system comprising an image display device for displaying an image, a light source device having a surface-emitting solid-state light source for providing light to the image display device, and an optical component for receiving image light from the image display device; The light source device is composed of a single light source module, which is composed of a surface-emitting solid light source and an optical element that narrows the divergence angle of the divergent light beam emitted by the surface-emitting solid light source. A plurality of the single light source modules are arranged in two dimensions to form a light source unit and an image display device. The light beam from the light source unit is incident on an image display device, and the image display device adjusts the intensity of the light according to an image signal to display an image on a screen; The light source module is constructed as follows: a divergent light beam from a surface-emitting solid-state light source is reflected on a reflective surface, converted into approximately parallel light, and placed near the focal point of a reflective optical element; a cylindrical hole is designed at the focal point of an end face of the reflective optical element, and the surface-emitting solid-state light source is placed in the hole; The reflective surface of the reflective optical element constituting the aforementioned single module is in a parabolic shape, the surface-emitting solid element is designed on its end face, and the reflected light beam exit surface opposite to it is in a hexahedron shape, and adjacent single optical modules are closely arranged and seamlessly connected; The light source device comprises a light source unit composed of a plurality of two-dimensionally arranged single light source modules, and is characterized in that the diameter of the inscribed circle of the hexahedron is substantially equal to the maximum diameter of the parabolic reflecting surface.

[0007] Light is provided to the image display device by the aforementioned light source device, wherein the light source device comprises a plurality of individual light source modules arranged two-dimensionally to form a light source unit, wherein holes are provided on the end faces of the individual light source modules, and the holes are approximately cylindrical along the optical axis direction including the focus of the reflective optical element, and the side surfaces of these cylinders refract a portion of the divergent light from the surface-emitting solid light source; By being reflected at different positions on the reflective surface of the aforementioned reflective optical element, the divergent light beam from the surface-emitting solid light source can be converted into a light beam with an approximately narrow divergence angle.

[0008] The light source device comprises a light source unit composed of a plurality of single light source modules arranged in a two-dimensional manner; The aforementioned single light source module is provided with a hole on its end face, which is approximately cylindrical along the optical axis direction including the focus of the reflective optical element, and the side surfaces of these cylinders refract part of the divergent light from the surface-emitting solid light source; By reflecting at different positions on the reflective surface of the reflective optical element, the divergent light beam from the surface-emitting solid light source can be converted into a divergent light beam with a narrow divergence angle, and the divergent light beam diverges from multiple focal points along the optical axis of the reflective optical element.

[0009] The light source device comprises a light source unit composed of a plurality of single light source modules arranged in a two-dimensional manner; The aforementioned single light source module has a hole on its end face, which is roughly cylindrical along the optical axis direction including the focus of the reflective optical element. The narrow-angle divergent light beam from the surface-emitting solid light source is incident on the front end face of the cylinder and is refracted by the lens shape provided on the front end face, thereby controlling the incident position and incident angle of the light beam incident on the reflective surface of the reflective optical element. A virtual image display device is provided, wherein the virtual image display device includes an optical system, the optical system comprising an image display device for displaying an image, a light source device including a surface-emitting solid-state light source for supplying light to the image display device, and an optical component for receiving image light from the image display device; The light source device comprises a light source unit composed of a plurality of individual light source modules arranged in a two-dimensional manner, wherein the individual light source modules are composed of a surface-emitting solid light source and an optical element for narrowing the divergence angle of a divergent light beam emitted from the surface-emitting solid light source; The image display device displays an image on a screen by causing a light beam from a light source unit to be incident on the image display device and adjusting the intensity of the light according to an image signal. The light source module converts a divergent beam from a surface-emitting solid-state light source into approximately parallel light by reflecting it on a reflective surface, and places the divergent beam near the focal point of a reflective optical element. A cylindrical hole is also provided at the focal point of an end face of the reflective optical element, and the surface-emitting solid-state light source is placed in the hole. The reflective surface of the reflective optical element constituting the aforementioned single module is formed by a plurality of regions, and the first region close to the aforementioned surface-emitting solid light source is in a parabolic shape; The second reflective region is located near the end face of the surface-emitting solid-state device and the opposite reflected light beam emission surface, and has different divergence characteristics from the reflected light beam of the first reflective region. The end face of the surface-emitting solid-state device and the opposite reflected light beam emission surface have a hexahedral opening shape, and adjacent single optical modules are seamlessly connected and neatly arranged. The inner diameter of the circumscribed circle of the hexahedron of the single light source module is equal to the maximum diameter of the second reflective area.

[0010] The light source device comprises a light source unit formed by a plurality of individual light source modules arranged in a two-dimensional manner. The individual light source modules are provided with holes on their end faces, which are approximately cylindrical along the optical axis direction including the focus of the reflective optical element. The side surfaces of these cylinders refract a portion of the divergent light from the surface-emitting solid light source. The divergent light beam of the surface-emitting solid light source is converted into a light beam having a divergent angle of approximately narrow angle by reflection through the reflective surfaces at different positions of the reflective optical element.

[0011] The light source device comprises a light source unit composed of a plurality of individual light source modules arranged in a two-dimensional manner. Holes are provided on the end faces of the individual light source modules, forming a substantially cylindrical shape along the optical axis direction including the focus of the reflective optical element. The side faces of these cylinders refract a portion of the divergent light from the surface-emitting solid light source. By reflecting at different positions on the reflective surface of the reflective optical element, the divergent light beam from the surface-emitting solid light source can be converted into a divergent light beam with a narrow divergence angle that diverges from multiple focal points along the optical axis of the reflective optical element.

[0012] The light source device is designed with a hole on the end face of the aforementioned single light source module, which is approximately cylindrical along the optical axis direction containing the focus of the reflective optical element. After the narrow-angle divergent light beam in the divergent light beam from the surface-emitting solid light source enters the front end face of the cylinder, it is refracted by the lens arranged on the front end face.

[0013] Among the light beams emitted by the aforementioned single light source module, the reflected light beams from the second reflection area in the side reflection area of the aforementioned reflective optical element diverge toward the image display device, and the divergent lights from multiple adjacent single light source modules overlap on the light incident surface of the image display device.

[0014] The light source device comprises a light source unit composed of a plurality of single light source modules arranged in a two-dimensional manner, wherein the single light source modules are formed of heat-resistant plastic material.

[0015] In the light source device, a single light source module is made of heat-resistant plastic with a heat-resistant temperature of more than 120 degrees.

[0016] Compared to the prior art, the present invention has the following advantages: a virtual image display device includes an optical system comprising a display panel for displaying an image, a light source device for providing light to the display panel, an optical assembly for receiving image light emitted from the display panel, and a light source device for controlling the emission direction of the image light entering the optical assembly. The diffusion characteristics of light emitted from the light source through the display screen toward the viewer are controlled by a light source unit designed within the light source device and an optical film designed between the light source device and the display screen, thereby controlling the diffusion characteristics and emission direction of the image light from the liquid crystal screen. This allows the emission direction of image light, whose light intensity is modulated according to an image signal from the image display device, to be controlled, as well as the incident position and angle of the incident image light entering the subsequent optical assembly. Therefore, in this optical system, by controlling the intensity and diffusion characteristics of image light emitted from the image display surface of the display panel serving as the image display device, the efficiency of image light entering the optical assembly can be improved, thereby forming an enlarged projected image. According to the present invention, as a light source device of an image display device, by controlling the directional characteristics and diffusion characteristics of the image light, in the design of an optical component that uses a concave mirror to obtain a magnified virtual image, by considering the diffusion characteristics of the image light emitted by the image display device, the performance of the optical component is improved, and a cost-effective optical component can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of an information image device and its peripheral devices related to an embodiment of the present invention; Figure 2 is a schematic structural diagram of an information display device, a front windshield, and a driver's viewpoint position related to an embodiment of the present invention; Figure 3 is a schematic structural diagram of an information display device, a front windshield, and a driver's viewpoint position related to another embodiment of the present invention; Figure 4A A top view of a car equipped with an information display device; Figure 4B is a diagram illustrating the difference in the radius of curvature of the front windshield; Figure 5 is a characteristic diagram illustrating the diffusion characteristics of a surface-emitting LED light source; Figure 6 A first characteristic diagram of the luminous characteristics of a general white surface-emitting LED; Figure 7 The second characteristic diagram of the luminous characteristics of a general white surface-emitting LED; Figure 8 A schematic diagram illustrating the outer shape of a typical white surface-emitting LED according to an embodiment of the present invention; Figure 9 Schematic diagram of the internal structure of a typical white surface-emitting LED; Figure 10 A schematic cross-sectional view illustrating ray tracing results of a light source optical component of an image display device according to the present invention; Figure 11 A graph illustrating the intensity variation characteristics of the light refractive index along the optical axis of the main components of the light source optical assembly of the image display device of the present invention; Figure 12 A schematic cross-sectional view illustrating ray tracing results of an LED light source and main components of a light source optical assembly of an image display device according to the present invention; Figure 13 A schematic cross-sectional view illustrating some of the main components of the light source optical assembly of the image display device of the present invention and the state of divergent light emitted by the LED light source; Figure 14 A schematic cross-sectional view illustrating the structure of the main components of the light source optical assembly of the image display device of the present invention; Figure 15 A schematic plan view illustrating the structure of the main components of the light source optical assembly of the image display device of the present invention; Figure 16 A schematic cross-sectional view illustrating the configuration of an image display device according to the present invention; Figure 17 A schematic cross-sectional view illustrating the shape of optical components constituting a light source optical assembly of an image display device according to the present invention; Figure 18 Transmittance characteristic diagram of an emissive polarizer at an incident angle of 10 degrees ± 10 degrees shown in an embodiment of the present invention; Figure 19 Transmittance characteristic diagram of the emissive polarizer at an incident angle of 50 degrees ± 10 degrees shown in an embodiment of the present invention; Figure 20 A conceptual cross-sectional view illustrating the functions of optical elements constituting a conventional light source device; Figure 21 A conceptual cross-sectional view illustrating the functions of optical elements constituting other conventional light source devices; Figure 22 An illustration of the diffusion characteristics of the light source device of the present invention; Figure 23A A diagram illustrating a coordinate system for testing visual characteristics of a liquid crystal panel serving as an image source, in accordance with one embodiment of the present invention; Figure 23B A diagram illustrating a coordinate system for testing visual characteristics of a liquid crystal panel as an image source in accordance with an embodiment of the present invention; Figure 24A A diagram illustrating a coordinate system for testing visual characteristics of a liquid crystal panel as an image source in accordance with an embodiment of the present invention; Figure 24BA diagram illustrating a coordinate system for testing visual characteristics of a liquid crystal panel as an image source in accordance with an embodiment of the present invention; Figure 25 A diagram illustrating the principle of a virtual image optical system using a concave mirror, related to one embodiment of the present invention; Figure 26 Illustration of the light diffusion invariant; Figure 27A An explanatory diagram of the configuration of an optical component and a design environment for an optical component including a concave mirror according to an embodiment of the present invention; Figure 27B This diagram illustrates how the amount of aberration produced by a projection lens or an optical assembly including a concave lens, which constitutes an optical assembly according to one embodiment of the present invention, varies with the image light diffusion characteristics. DETAILED DESCRIPTION

[0018] The following describes embodiments of the present invention with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below (hereinafter also referred to as the "present disclosure"). The present invention also extends to the scope of the technical concepts described in the spirit of the invention or the claims, or to equivalents thereof. The configurations of the embodiments (examples) described below are merely illustrative, and various changes and modifications can be made by those skilled in the art within the scope of the technical concepts disclosed in this specification.

[0019] In the drawings for explaining the present invention, the same reference numerals are used for elements having the same or similar functions, and descriptions of overlapping functions and the like will be omitted where appropriate even if different names are used.

[0020] In the following description of the embodiments, the term "magnified virtual image" refers to a virtual image formed in space by an optical assembly using a concave mirror. The term "magnified real image" refers to a real image formed in space by an optical assembly using a lens assembly with positive refractive power or a convex lens. These terms can also be referred to as "magnified image," "virtual image," or "real image." The term "magnified virtual image" is primarily used in describing the embodiments as a representative example of these terms.

[0021] The present disclosure relates to an optimized design method for an optical component that displays an image of a small image light source that produces an image beam with a narrow divergence angle as a virtual image or a magnified image of a real image, as well as embodiments of the virtual image optical component obtained thereby and an optical system using the same. According to the present invention, by optimizing the design of an optical component that uses a projection lens to obtain a magnified real image and an optical component that uses a concave mirror to obtain a magnified virtual image, the diffusion characteristics of the image light emitted from the image source are taken into consideration. This can reduce the need for a large-diameter optical component and the number of lenses and reflectors, thereby obtaining a cost-effective optical component structure. In particular, because the brightness of the magnified virtual image is equal to that of the light source, it has excellent light energy conversion efficiency.

[0022] Overview of the vehicle information display system of the present invention, Figure 4A This is a top view of an information display device 1000 according to an embodiment of the present invention, mounted on a vehicle such as a car, train, or airplane. In front of the driver's seat of the car 1010, there is a front windshield 6, which serves as a projection element. The angle of inclination of the front windshield 6 relative to the vehicle body varies depending on the type of vehicle. Furthermore, the inventors investigated the radius of curvature of the optical component to achieve the optimal virtual image. It was found that, if Figure 4B As shown, the curvature radius of the front windshield 6 relative to the ground contact surface of the vehicle is different in the horizontal direction, the curvature radius Rh, and the vertical curvature radius Rv perpendicular to the horizontal axis. The curvature radius Rh and the vertical curvature radius Rv are different in the horizontal direction, and the curvature radius Rh and the vertical curvature radius Rv are different ... in the horizontal direction, and the curvature radius Rh and the vertical curvature radius Rv are different in the horizontal direction Rh>Rv Furthermore, it was found that the difference in these radii of curvature, ie, the ratio of Rh to Rv, was generally in the range of 1.5 to 2.5 times.

[0023] In the present invention, image information is reflected and displayed through the front windshield, which allows the driver to observe the external scenery while driving. The information display device emits an image beam with a narrow divergence angle and adjusts its emission direction according to the position of the image. This allows the optical components of the head-up display to effectively capture the incident beam, thereby providing a high-brightness virtual image that can be properly displayed.

[0024] One embodiment of a head-up display device is an information display device that displays virtual images on a projection surface. It consists of an image light generating unit that generates the displayed image information and a light source device that supplies light to the image light generating unit. This light source device, located between the surface light source and the image display device (liquid crystal panel), includes an optical element that converts the light generated by the surface light source into light with a desired divergence angle, and includes means for controlling the divergence angle and directional characteristics.

[0025] The first information display device of the vehicle information display system of the present invention is Figure 1This is a schematic diagram of the peripheral equipment structure of the first type of information display device in the vehicle information display system of the present invention. Here, an example is described of an information display device 100 that projects an image onto the front windshield 6 of a vehicle. The head-up display (HUD) of the information display device 100, as the first embodiment of the present invention, forms a virtual image V1 in the driver's line of sight (viewpoint, described in detail later) 8 in front of the vehicle. It displays various information reflected from the projection element (in this embodiment, the inner surface of the front windshield 6) as a virtual image VI. This device is also known as a HUD (Head-Up Display). The control device 40 that constitutes the HUD is shown. It obtains various information corresponding to the vehicle's current location from the navigation system 61, such as the road speed limit, number of lanes, and the vehicle's planned travel path set in the navigation system 61, as foreground information (i.e., the information displayed in front of the vehicle via the virtual image).

[0026] Furthermore, the illustrated driving 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 to implement driving assistance control. Such driving assistance control includes well-known technologies such as cruise control, adaptive cruise control, pre-collision safety systems, and lane keeping assist.

[0027] The illustrated peripheral monitoring device 63 is a device for monitoring the surrounding conditions of the vehicle, such as a camera that detects objects around the vehicle based on images taken around the vehicle, or a detection device that detects objects around the vehicle based on the results of sent and received detection waves.

[0028] The control device 40 of the HUD device described above obtains foreground information by using information obtained from the driving assistance ECU 62 (e.g., the distance to the preceding vehicle and its orientation, the location of obstacles or signs, etc.). In addition, the control device 40 also receives an ignition (IG) signal and vehicle status information. The vehicle status information refers to information obtained as vehicle information that does not require high-resolution display, such as the remaining fuel volume and cooling water temperature related to internal combustion, including the display of pre-defined abnormal status warning information. In addition, it also includes the operation results of the direction indicator, the driving speed of the vehicle, and the shift position information. The control device 40 described above is activated when it receives the IG signal. The above is a description of the overall system of the information display device of this embodiment.

[0029] Furthermore, the projected component can be any component for projecting information, not just the aforementioned front windshield 6, but can also be other components, such as a combination screen. In other words, as long as the information display device 100 of this embodiment can form a virtual image in front of the vehicle so that the driver can see it in the line of sight 8, it will be sufficient.

[0030] In information display device 100 having the above structure, the image displayed by image display device 104, which projects image light displaying information, is transformed into a virtual image by concave (free-form surface) mirrors 105 and 106. Distortion and aberration caused by these two mirrors are corrected. The image light beam emitted from information display device 100 is directed toward front windshield 6 through an opening (not shown).

[0031] In addition, as a second embodiment of the information display device 100, Figure 1 As shown, the image displayed by the image display device 103 can be directly reflected into the driver's sight. Its structure and function will be described as follows Figure 3 Detailed description. The image display device 4 includes a control device 40 (not shown) for controlling the backlight. Furthermore, in the first embodiment described above, the optical components including the image display device 104 and the backlight 102 are a virtual image optical system, also described below, which includes a light-reflecting concave mirror 1. On the other hand, the second embodiment reflects the high-brightness display image of the image display device 4 directly onto the front windshield 6, toward the driver's line of sight 8.

[0032] In addition, if Figure 1 As shown, the image display devices 103, 104 and Figure 3 The image display device 4 shown is, for example, an LCD (Liquid Crystal Display) having a backlight. Alternatively, a self-luminous VFD (Vacuum Fluorescent Display) or the like may be used.

[0033] On the other hand, Figure 2 As shown, the image of the image display device 403 can be reflected as a virtual image through the projection component, i.e., the front windshield 6 or the combination screen (not shown) toward the driver's viewpoint 8 by the concave mirror 1a.

[0034] Here, in order to reduce the distortion of the virtual image, the shape of the concave mirror 1a is as follows: Figure 2 The upper portion (the light reflection area below windshield 6, which is relatively close to the driver's viewpoint 8) has a relatively small radius of curvature, resulting in a higher magnification ratio. The lower portion (the light reflection area above windshield 6, which is relatively close to the driver's viewpoint) has a relatively large radius of curvature, resulting in a relatively lower magnification ratio. Furthermore, the image display device 4 is tilted relative to the optical axis of the concave mirror 1a to correct for differences in virtual image magnification, thereby reducing distortion and achieving a better correction effect.

[0035] On the one hand, the front windshield 6 of the passenger car, such as Figure 4BAs shown, the vertical and horizontal radii of curvature Rv and Rh of the main body are different, with Rh generally greater than Rv. Therefore, if the windshield 6 is considered a reflective surface, it is identical to the concave surface of the concave mirror 1. Therefore, in the information display device 100 of this embodiment, the shape of the concave mirror 1 should be adjusted to the shape of the windshield to correct the virtual image magnification. Specifically, different average radii of curvature are used in the horizontal and vertical directions to compensate for the difference in the vertical and horizontal curvature radii of the windshield 6. In this case, the shape of the concave mirror 1 is a spherical or aspherical surface symmetrical about the optical axis (see [Equation 2] below), which is a function of the distance from the optical axis r. Since the shapes of the horizontal and vertical cross-sections at a distance cannot be controlled independently, it is best to use a free-form surface as shown in [Equation 1] below, with compensation performed as a function of the mirror's optical axis coordinates (x, y).

[0036] According to the following embodiments, for example, Figure 25 As shown, a high-resolution magnified image BB' can be displayed behind the concave mirror. In this case, by reducing the scattering angle of the image light emission to an acute angle and adjusting it to a specific polarization, the concave mirror can effectively reflect only the normal reflected light.

[0037] When using a liquid crystal display (LCD) panel (or display panel) as an image display device that produces image light of a specific polarization, a depolarization element can be installed on the viewer side of the LCD panel (i.e., the optical component side). This optically converts a portion of the image light to a different polarization direction, resembling natural light. This allows the viewer to see a high-quality magnified virtual image even when wearing polarized sunglasses.

[0038] Commercially available polarization cancellers include CosmoShine SRF (manufactured by Toyobo Co., Ltd.) and polarization canceller adhesive (manufactured by Hase Kogyo Co., Ltd.). CosmoShine SRF (manufactured by Toyobo Co., Ltd.) can reduce interfacial reflection and improve brightness by applying an adhesive to an image display device. Furthermore, when using a polarization canceller adhesive, it can be applied between the image display device and a colorless transparent plate, acting as an adhesive. In this embodiment, as previously described, the image display device 1 includes a liquid crystal display panel 11 and a light source device 13 that generates narrow-angle diffusion characteristics and generates specific polarized light. This allows efficient light utilization and produces an optical system that enables outdoor viewing of magnified virtual images, which is unattainable with conventional virtual imaging technologies. This is achieved by a low-power, portable, and compact image display device.

[0039] Furthermore, the light source device and optical assembly disclosed herein can significantly reduce energy consumption. Combined with a novel, compact image display device (liquid crystal display panel), a low-power, portable magnified virtual image display system can be provided. The disclosed technology can also provide an image display device capable of displaying a unidirectional magnified virtual image, visible from a specific direction within the vehicle, such as through the vehicle's windshield, rearview glass, or side glass.

[0040] Next, as an embodiment of the invention disclosed in this application, the operation of an optical system for obtaining an enlarged virtual image and an embodiment of a specific optical system will be described. Figure 26 The basic structure of an optical system for obtaining a magnified virtual image is shown. The object (AA') is placed on the mirror side of the focal point F of the concave mirror 1'.

[0041] At this time, PB” / AA’=PF / AF=f / (fa), PB”=BB’, therefore, BB′ / AA′=f / (fa), which can be expressed as formula (1) Due to the similarity between △PA"F and △BB'F BB′ / PA′′=BF / PF=(b+f) / f, expressed as formula (2) Because PA”=AA’, so: BB′ / AA′=(b+f) / f Since the left sides of formula (1) and formula (2) are the same, we get: (f / (fa))=(b+f) / f f2=(b+f)(fa) f2=bf+f2-ab-af 0=bf-ab-af, we get: bf-af=ab, divide both sides of this equation by abf: (Change) (bf / abf)-(af / abf)=(ab / abf) (1 / a)-(1 / b)=(1 / f), expressed as formula (3) Formula (3) is derived from the coordinate definition of the optical components: (1 / a)+(1 / (-b))=(1 / f) At this time, the magnification m of the virtual image is: =b / a Therefore, by reducing the distance b from the object to the concave mirror (the object point distance) and increasing the distance from the concave mirror to the virtual image, that is, the image distance, a high-magnification virtual image can be obtained.

[0042] In an optical system using the aforementioned virtual image optical assembly, the focal length f must be shortened to shorten the distance between the object point AA' and the concave mirror 1. However, to shorten the focal length, the refractive index of the concave mirror must be increased. Conventional optical design methods, however, increase the aberrations of the magnified virtual image, resulting in blurring of the magnified virtual image.

[0043] A novel design method of a small, high-brightness and high-resolution virtual image magnification optical component will be described based on the following drawings. Figure 22 、 Figure 23A and Figure 23B These are explanatory diagrams for explaining the scattering characteristics of image light emitted from the center of the display screen of an image display device. These explanatory diagrams are for explaining the scattering characteristics when the liquid crystal panel 104 is used as a display element of the image display device. Figure 23A The image shows an oblique view of the LCD panel 11 installed with the light-emitting surface facing upward. For ease of explanation, the long direction of the image is defined as the X-axis, the short direction as the Y-axis, and the direction perpendicular to the XY plane as the Z-axis. When describing the scattering angle of image light, the Z-axis will be used as the axis indicating relative brightness.

[0044] Figure 27A This figure shows the basic design environment used when designing an optical system. The LCD panel is defined as the object plane, the line segment connecting the center of the screen and the center of the optical component's entrance pupil is defined as the Z-axis, and the LCD panel is placed on a plane perpendicular to the Z-axis (the XY plane). In optical system design, for example, a ray is emitted from the object point Pa at the center of the screen toward the current coordinates of the relative pupil height (-1.0 to +1.0 on the Y-axis, -1.0 to +1.0 on the X-axis) of the entrance pupil, which is a virtual plane. The amount of shift in the XY plane of the principal ray from its endpoint on the image plane toward the center of the object point and the entrance pupil (relative pupil height (0.0, 0.0)) is defined as the aberration amount, and the optical system is designed to achieve zero this aberration.

[0045] Conventional optical component design parameters include the placement and shape of the optical elements between the liquid crystal panel (the object point) and the magnified virtual image (the image plane), as well as the refractive index. In virtual image optical components using concave mirrors, the position and shape of the concave mirrors are key design parameters. Furthermore, because the diameter of the human pupil varies depending on the amount of light entering the retina (the pupil diameter varies between 4mm and 8mm depending on the amount of light entering the retina), it can block unwanted light. Image light that exceeds the distance from the image plane to the viewer and the angle covered by the pupil diameter will not reach the retina. Therefore, when designing such optical components, it is necessary to fully consider the role of the human retina as a light-blocking material.

[0046] In the present invention, a liquid crystal panel is used as an image display device, and the diffusion characteristics of the light source device are made to present a narrow angle. The diffusion of the image light is adjusted by the shape and surface roughness of the reflective light guide of the light source, which is used as a new optical component design parameter. In the embodiment of the present invention described below, the diffusion characteristics of the horizontal (long direction) of the picture are designed to be ±9 degrees at a relative brightness of 50% and ±16 degrees at a relative brightness of 0%; the diffusion characteristics of the vertical (width direction) of the picture are designed to be ±7.5 degrees at a relative brightness of 50% and ±13 degrees at a relative brightness of 0%. The optical component that emits the image light beam from the object point Pa at the center of the picture is as follows. Figure 24A As shown, the coordinates of the relative pupil height and the resulting aberrations are as follows Figure 24B (1) As shown in FIG. The aberration-generating region of the image light beam generated by the image light source of the present invention is the B range, which is closer to the principal ray than the A range corresponding to the divergence angle of the light beam required to obtain the same brightness in conventional designs. Therefore, the amount of aberration generated itself is significantly reduced.

[0047] In addition, if Figure 27B As shown in (2), regarding the image beam emitted from the object point Pb around the picture, and Figure 27B The aberration in the longitudinal cross-section direction shown in (2) is the same as the aberration in the spherical segment cross-section direction shown in the figure below. The aberration occurrence area of the image light beam generated by the image light source of the present invention having a narrow divergence angle diffusion characteristic is the B range. Therefore, compared with the A range corresponding to the beam divergence angle required to obtain the same brightness in the conventional design, it is closer to the main light, so the amount of aberration itself is greatly reduced.

[0048] In conventional optical systems, if aberration correction is insufficient, optimal focusing performance can be achieved by optimizing the diameter of the barrel that holds the lens elements in the optical assembly. This can be achieved by configuring the lens groups to determine the effective diameter of the lens, adjusting the width of the image beam at the center of the frame to determine brightness (F-number), and blocking areas with significant aberrations. Furthermore, for light beams forming at the periphery of the frame, the effective diameter of the lens is determined by configuring the lens groups, and blocking areas with significant aberrations to achieve practical, reliable focusing performance. On the other hand, to ensure sufficient brightness both at the center and at the periphery of the screen, the number of transmitted light beams must be increased as much as possible.

[0049] This is because, according to the cosθ4 law between the object plane and the magnified projected image plane, the relative brightness of the peripheral image plane will further decrease, making it more difficult to make it equal to the brightness of the center of the screen.

[0050] In contrast, the optical system of the present invention, as described above, is equipped with a light source device capable of controlling the image light beam emitted by an image display device with narrow-angle scattering characteristics, emitting it in the direction desired by the optical assembly. The following describes in detail this light source device with narrow-angle scattering characteristics and controllable light emission direction, as well as its surface light source LED (Light Emitting Diode).

[0051] The present invention describes the surface-emitting LED and its light diffusion characteristics. Generally, a surface-emitting white LED is formed by coating a yellow luminescent material including green and red light on the surface of a blue LED. The yellow phosphor is excited to emit yellow light, thereby mixing to produce white light. The light diffusion characteristics of a surface-emitting white LED are that when the light-emitting surface of the LED light source is facing upward, the relative brightness corresponding to the divergence angle of the light emitted from its light point is as follows: Figure 5 The fully diffused distribution shown in the figure is generally structured as follows: In order to capture light with a large divergence angle, the optical component is usually placed close to the surface light source LED. To more easily control the diffusion characteristics and directivity of the light beam emitted by the LED, the emitted light beam is first converted into a parallel beam by an optical component (optical element). The diffusion characteristics and directivity are then controlled by the optical element installed between the liquid crystal panel and the optical component. Optical components used in traditional light source devices such as Figure 20 and Figure 21 As shown, multiple LEDs are placed close to corresponding plano-convex lenses LA, converting the divergent light beams emitted by the LEDs into nearly parallel light. Optical elements LB and FL, located between the LCD panel and the LEDs, control the beam's directional characteristics, while diffusers DF1 and DF2 control the beam's diffusion angle. In traditional optical systems, the incident beam angle at each optical element is large, resulting in increased reflection losses.

[0052] also, Figure 20 and Figure 21 The optical assembly used in the conventional light source device shown is composed of a plurality of optical components (elements) arranged in an array. Figure 20 In the first conventional example shown, there are five reflective surfaces. Figure 21 In the second conventional example shown, there are 7 reflective surfaces. When light is incident perpendicularly on an optical element with a refractive index of 1.5, the reflectivity is 5% per surface. As previously mentioned, due to the large incident angle of conventional light source devices, the reflectivity increases further, with the average reflectivity exceeding 8%. In the first conventional example, there are 5 reflective surfaces, and the reflection loss of the entire optical assembly is over 40%. On the other hand, in Figure 21 In the second example shown, there are seven reflective surfaces, so the reflection loss of the entire optical system is more than 56%. The large reflection loss significantly reduces the light utilization efficiency of the light source device.

[0053] The first embodiment of the optical component used in the light source device of the present invention: The following examples are Figure 6 and Figure 7 An image display device will be described based on the white LED shown. Figure 6 The first white LED shown and Figure 7 The second white LED shown differs from the first embodiment in that the peak wavelength of the blue LED, which excites a yellow phosphor containing green and red, is shifted to a shorter wavelength, resulting in white light with a higher color temperature. The light source assembly of this image display device includes an optical component that controls the divergence angle and direction of the light emitted by this white light LED. The intensity of the resulting light source can be modulated according to an image signal, and an image can be displayed on a color filter LCD serving as the image display element.

[0054] The following embodiments primarily describe a light source device for use with a color filter LCD panel as an image display element, and a light source optical assembly including this light source device. The light source optical assembly of this embodiment of the present invention can also be used as a highly efficient light source using an LCD panel light source, thus enabling its use in projection-type image display devices and other HUD image display devices.

[0055] The light source device, the optical assembly, and the characteristics of the optical components of the image display device of the embodiment of the present invention are described below.

[0056] The light source in the light source optical assembly of the present invention adopts a surface emitting solid light source, using a blue LED, mixed with yellow light generated by exciting a yellow phosphor containing green and red to obtain white light. Its diffusion characteristics are as follows Figure 1 The figure shows a completely diffuse distribution. To capture and efficiently utilize light from a light source with a large divergence angle, a plano-convex lens with a large aperture receiving surface needs to be configured near the LED light-emitting surface. In the design of the lighting component, the area and divergence angle of the light-emitting surface and the area and collection angle of the receiving surface must satisfy the equal luminance invariant characteristic (such as Figure 26 As shown in Figure 2, conventional light source optical components have the problem of being unable to efficiently utilize the divergent light beams emitted by LEDs. The present invention solves these problems through the following technical means.

[0057] In the embodiment of the present invention, the divergence angle of the light source is shown in Figure 23, which shows a narrow-angle divergence characteristic. Compared with the fully diffused characteristic of ordinary surface-emitting LEDs shown in the figure, the divergence angle of the light beam is narrow, thereby increasing the light energy density and improving the brightness of the image displayed on the subsequent LCD. Figure 14 and Figure 15As shown, a single light source module including a reflective optical element 11 achieves both narrowing the divergent light beam angle and controlling its directivity. Narrowing the divergent light beam angle is controlled by the shape of the reflective surface of the reflective optical element 11, while directivity can be easily adjusted by optimizing the relationship between the reflective surface's focal position and the center of light emission of the surface-emitting white LED in the XY plane.

[0058] As described above, in the embodiments of the present invention, by arranging divergent beams with narrow divergence angles and single light source modules with controllable directivity in a planar direction, the divergent beams of surface-emitting LEDs can be precisely controlled like lasers (LASER, Light Amplification by Stimulated Emission of Radiation).

[0059] In the embodiment of the present invention, the surface emitting LED is placed Figure 10 At the focal point of the reflective surface shown, the divergent light from the surface light source is converted into a beam approximately parallel to the optical axis (Z axis) of the reflective surface. In this case, since the reflective surface primarily controls the diffusion characteristics of the diffuse light, even a white light source will not produce chromatic aberration. Surface-emitting light source 1 cannot be spatially arranged and cannot capture light from area a, so the corresponding reflective surface needs to be cut off, such as Figure 12 and Figure 13 As shown, the end surface is designed to be approximately flat so that the LED driver substrates can be arranged in close proximity.

[0060] The composite focus of reflective optical components, the appearance of surface-emitting LED components such as Figure 8 As shown, it is wrapped inside a shell with a blue LED inside and a phosphor encapsulated around it with an inorganic encapsulation material. Figure 9 This is a cross-sectional view of a common surface-emitting white LED. The blue LED chip (element) 5 is mounted on a substrate 6, and the blue light emitted from it is used as excitation light by the surrounding green and red yellow phosphors to obtain Figure 6 and Figure 7 The white light shown contains the three primary colors of blue, green and red. In ordinary surface-emitting white LEDs, the surrounding area of the blue LED element light emitting area ( Figure 9 The light intensity in area 2 is the strongest, so the proportion of white light generated is the highest among the packaged phosphors.

[0061] In an embodiment of the present invention, by Figure 16 and Figure 17 The reflective polarizer 19a ( Figure 17(A) ) can reflect P polarized light. The blue light component of the P polarized light returned by the surface-emitting white LED is used as the excitation light of the phosphor again, thereby emitting light on the surface of the phosphor ( Figure 9 Therefore, the surface-emitting white LED used in this embodiment has high luminous intensity not only in area 2 but also in an area close to the phosphor-coated surface (area 3 in the figure).

[0062] As a result, multiple luminous points with high luminous intensity are formed along the Z axis in the embodiment, thereby increasing the degree of freedom in controlling the topological characteristics of the reflective optical element. This is the first unique advantage of the present invention.

[0063] In the embodiment of the present invention, it is possible to realize that there are multiple focal points along the aforementioned Z-axis direction. Specifically, when optimizing the focal position of the reflective optical element 11, the surface-emitting white LED is arranged at Figure 10 The parabola focal position is shown. This results in multiple luminous points along the Z-axis, so a composite focal point reflective surface needs to be designed based on a new design concept.

[0064] In addition, the general method of improving the light utilization efficiency of surface light source white LED is to reduce the light emitting area. Therefore, the light emitting area of surface light emitting white LED with high light output has been rapidly reduced in recent years. In the embodiment of the present invention, it is necessary not only to optimize the optimal shape of the multiple light emitting points formed by the reflective optical element 11 along the Z-axis direction, but also to consider the assembly accuracy of the miniaturized surface light emitting LED. Figure 8 As shown, even if the light-emitting point moves in the XY direction within the light-emitting surface, as long as the light-emitting point is within a specific range, the light receiving efficiency will not drop significantly. In other words, in order to reduce assembly accuracy, it is necessary to design a composite focal reflective optical element 11 with multiple focal planes within the XY plane.

[0065] The following is a description of the design of the reflective surface of the reflective optical element 11 having multiple focal points in the horizontal and vertical directions. Figure 10 FIG is a schematic diagram of a vertical cross section of the reflective optical element 11, showing a vertical cross section of the element along the Z axis. In the region a along the Z axis, since the divergent light of the surface-emitting white LED at the focus cannot be captured, Figure 12 In the cross section of the optical element 11 shown in FIG, a hole is provided in a part of the end surface thereof (such as Figure 13 As shown in the figure), the surface-emitting white LED is placed at the optimal position along the Z axis of the reflective optical element by the refraction effect generated by the shape of the hole. Figure 13As shown, a substantially cylindrical hole is provided on the end face of the reflective optical element 11 (also referred to as a single light source module) in the area aligned with the optical axis. A surface-light white LED is positioned within this space. Because the reflective optical element and the LED light source are positioned close together, a high-temperature-resistant plastic material (with a heat distortion temperature of 120°C or higher) is recommended for the substantially cylindrical hole. Furthermore, a draft angle of at least 2 degrees is required between the end and tip of the mold to facilitate removal from the mold during molding, significantly improving the release performance of the molded part.

[0066] Figure 13 The divergent light from the surface-emitting white LED shown in the figure is refracted by the cylindrical hole wall and originally diverges in the direction shown by the dotted line (incident angle θ5 based on the wall). However, due to refraction at the wall, the divergent direction changes to the direction shown by the solid line (incident angle θ4 based on the wall). Therefore, with respect to Figure 13 The first focal point of the individual light source module at the intersection of the dashed lines (i.e., the location of the LED light source) generates a second focal point slightly further away in space (at distance L1). The position of this second focal point can be arbitrarily designed based on the inner diameter of the approximate cylindrical shape, the inclination angle of the wall surface, and the refractive index of the material; these parameters are effective design parameters in the shape design of the individual optical module. Light beams refracted by the cylindrical side and reflected by the reflective surface of the individual optical module (area b in the figure) are converted into roughly parallel beams due to the paraboloidal surfaces corresponding to their respective focal points, and are emitted toward the LED. Area c, farthest from the LED light source, is designed to diverge along the paraboloidal surface.

[0067] The top surface of the cylindrical shape has a lens shape, and the divergence angle of the surface-emitting white LED is controlled by refraction of the divergence angle in a small range. The design of this shape can be shown in the figure. Since the refractive power of the area a around the optical axis and the surrounding area b is different, the shape design can be used to more accurately control the light distribution. The divergence angle of the light beam incident on these areas is about ±15 degrees. According to Snell's law, the refracted light can be effectively controlled. As described above, the divergent light from the surface-emitting white LED set at the first focus passes through the reflective surface shape of the single optical module in the embodiment of the present invention, as shown in FIG. Figure 8 The dotted line portion shown forms an almost parallel light beam, which then travels to the color filter LED in the lower section.

[0068] On the other hand, due to the lens effect of the cylindrical side wall, a divergent light of the second focus is generated, as shown by the solid line in the figure, and several divergent light beams are emitted from a single optical module. This result makes Figure 15The arrangement of the individual light source modules shown can reduce light intensity variations at the boundaries between adjacent optical units, thereby improving the technical potential.

[0069] Next, if Figure 11 As shown in the embodiment of the present invention, the refractive power changes of the reflective optical element 11 (single light source module) along the optical axis are described. When designing, the refractive power of area c will gradually weaken compared with area b, and the divergence effect will increase. Figure 15 The brightness of the connection between adjacent individual light source modules in the final form is shown. During design, the image light emitted by the LCD panel with color filters is designed to have a uniform light source when the brightness ratio at the connection between the individual light source modules is less than 3%. In this case, in addition to the shape of the individual light source modules, the effect of the optical film for controlling the diffusion angle, described later, can be used to mitigate the effects of design parameters.

[0070] Regarding the description of the universality of a single light source module of the present invention, the final light source unit 12 is as follows Figure 15 As shown, it is composed of multiple individual light source modules 13 arranged in an array. Table 1 shows a representative example of a color filter LCD currently available in the market for automotive applications. To ensure component compatibility, individual light source modules of the same shape (hexagonal circumcircle diameter of 16 mm) were arranged in an array. This result demonstrates that the mold used to mold the light source unit allows the use of identically shaped inserts for each individual light source module, improving development efficiency.

[0071] When observing from the opening, a single light source module 13 having a parabola symmetrical with respect to the optical axis is formed. Figure 14 As shown in the plan view on the right, it is circular. A light source unit composed of multiple such units is arranged to reduce space loss, such as Figure 15 As shown, the elliptical shape including the reflection area c should be arranged into a hexahedron that appears circular when viewed from above.

[0072] In addition, if Figure 14 As shown in the plan view on the right, the maximum diameter of reflective surface b is aligned with the inscribed circle of the aforementioned hexahedron, and the shape of region c controls the diffusion characteristics of the areas corresponding to the six vertex corners of the hexahedron. This arrangement of individual optical elements creates a light source unit 12 that achieves excellent brightness uniformity, thereby providing new design freedom.

[0073] At the same time, if cheap surface-emitting white LEDs can be obtained, the circumscribed circle diameter of a single light source module can be reduced, and the number of arranged single light source modules can be increased, it will be easier to improve the brightness uniformity of the light source unit.

[0074] In an embodiment of the present invention, Figure 16The cross-sectional structure of the image display device is shown. Below the light source unit 12 composed of a plurality of individual light source modules 13, surface-emitting white LEDs corresponding to the individual light source modules 13 are arranged, and a series-connected LED driving substrate 16 is provided. The substrate adopts a metal substrate in consideration of heat dissipation. In order to reduce the difference in luminous brightness, it is better to drive the LED in series. However, if the number of connections is too large, the total voltage will increase, leading to problems in the insulation design of the circuit, etc. Therefore, it is best to limit it to a maximum of about 10, and adopt a combination of series and parallel connections. When adopting a combination of in-line and parallel connections, the problem faced is the difference in driving current between parallel circuits, which can be solved by setting a matching impedance circuit on each branch circuit. In this way, the difference in luminous intensity of the surface-emitting white LEDs can be reduced, thereby realizing a high-brightness and uniform brightness image display device.

[0075] Regarding the description of the optical film for controlling diffusion characteristics of the present invention, the following describes the structure and function of the optical film 19 (hereinafter referred to as the light diffusion control film) provided between the light source unit 12 and the LCD panel 20 with a color filter. Figure 17 The figure shows the cross-sectional shape of the optical film that controls the light diffusion angle. A reflective polarizer 19a, which reflects specific polarized light, is provided on the surface in contact with the light source unit 12. As previously mentioned, this specific polarized light emitted by the light source unit 12 is reflected back toward the phosphor of the LED light source 1 within the individual light source module 12, where it is reused as excitation light, thereby increasing the amount of light emitted and improving the luminous efficiency of the input power.

[0076] like Figure 16 As shown, the composite surface of the LCD panel 20 with the light diffusion control film 19 forms a Figure 17 (A) shows the fine pattern 19b used to control light diffusion. In this embodiment, to control the horizontal diffusion angle of the screen, a structure (H-shaped lenticular lens) is used, in which lenticular lenses are arranged horizontally with the LCD display. This controls the diffusion characteristics in the horizontal direction (i.e., the left-right direction in the figure) of the screen, improving the brightness uniformity of the image displayed on the LCD panel.

[0077] As shown in the enlarged view of section A, the cylindrical lens structure has convex surfaces in the direction of light emission. By minimizing the shape variation at the junctions between adjacent convex surfaces, a gentle concave surface is formed, or there is no abrupt change in lens action between the gently concave surface and the flat surface. Furthermore, the light-diffusing film 19 is arranged at an angle θ relative to the shape of the LCD panel 20, as shown in section B, through the cylindrical lens. This not only prevents moiré patterns caused by pixel interference but also controls vertical light diffusion, significantly improving the brightness uniformity of the image light emitted from the LCD panel 20.

[0078] The second technical approach mentioned above to avoid moiré caused by interference with the LCD panel is to choose a lenticular lens pitch that is not an integer multiple of 80μm if the pixel pitch is 80μm. The smaller the pitch, the higher the brightness uniformity of the screen. However, due to manufacturing limitations, refinement has its limits. Choosing a pitch between 100μm and 200μm can achieve good diffusion characteristics without generating moiré.

[0079] The first method for reducing moiré is to tilt the cylindrical lens. The tilt angle θ is preferably between 5 and 15 degrees. According to experimental results, the best effect is achieved within the range of 10 ± 3 degrees.

[0080] Regarding the description of the reflective polarizing film of the present invention that reflects specific polarized light, the angle dependence of the transmittance of the reflective polarizing film that reflects specific polarized light was studied for an optical film attached to the side of an LCD to control the light diffusion angle. The product actually studied was 3M™ DBEF-QV2, and in addition to studying the wavelength characteristics of the incident light, the change in the characteristics due to the incident angle was also studied. Figure 18 The characteristics of reflective polarizing films at normal incidence and incident angles close to it are summarized.

[0081] The wavelength transmittance of the other polarized light (P polarized light) varies significantly relative to the transmittance of the specific polarized light (S polarized light). However, the absolute value of the change is small when the change is less than 5%. In this case, reflecting P polarized light is feasible. In addition, there is no significant difference in the characteristics at incident angles of 10 degrees and 20 degrees. A portion of the light from the light source unit 12 with a diffusion angle is also reflected without angle dependence. For the characteristics at an incident angle close to 45 degrees, such as Figure 19 As shown, it also has good characteristics.

[0082] In an embodiment of the present invention, a reflective polarizing film was attached to the light source side of a light diffuser film, similar to the reflection of S-polarized light. The results showed that the S-polarized light was reflected back toward the light source, while the P-polarized light entered the lenticular lens of the light diffuser film. Because the P-polarized light beam, compared to the S-polarized light beam, has a Brewster angle (0% reflectivity) at an incident angle of approximately 33 degrees, the refractive index is lower in the areas around this angle (±15 degrees). Therefore, even without an anti-reflection coating on the lenticular lens surface, the desired light diffusion angle can be achieved without angular dependence.

[0083] Image light diffusion characteristics of the image display device of the present invention: In order to realize a compact and high-brightness image display device, it is necessary to control the directivity of light and obtain image output light with a narrow divergence angle. Figure 23AThis is an explanatory diagram for explaining the diffusion characteristics of image light emitted from the center of the display screen of an image display device. It is also an explanatory diagram for explaining the diffusion characteristics of the display element of the image display device when using the liquid crystal panel 20.

[0084] In FIG23 , the liquid crystal panel 20 is an oblique view with the light emitting surface facing upward. Figure 23A The coordinate axes are the long side of the screen as the Y axis, the short side as the X axis, and the perpendicular direction of the plane formed by the XY axis as the Z axis. In the description of the image light divergence angle in 23B, the Z axis is described as the axis representing relative brightness.

[0085] This invention utilizes a liquid crystal display panel as an image display device, while also utilizing the diffusion characteristics of the light source device to narrow the angle of view, thereby controlling image light over a wide range. To this end, design parameters for a new optical component constituting the light source unit 12 were determined, adjusted by the shape of the reflective optical element and the surface shape of a light diffuser sheet as required. In the implementation of this invention, the characteristic design values are as follows: the horizontal diffusion characteristic (long-side direction) of the screen is: ±9 degrees at a relative brightness of 50%; ±16 degrees at a relative brightness of 0%. The vertical diffusion characteristic (short-side direction) of the screen is: ±7.5 degrees at a relative brightness of 50%; ±13 degrees at a relative brightness of 0%.

[0086] In this case, the brightness of the image displayed on the image display device can be approximately 10 times higher using the characteristic C of the present invention compared to the image brightness of a standard diffusion characteristic close to a completely diffuse surface. Characteristic A, with its narrow-angle diffusion characteristic, further enhances the brightness. However, it should be noted that the directional characteristics of the light source device must be adjusted according to the viewer's viewing angle of the image display device, which also introduces new challenges for the light source device.

[0087] Etendue invariants for specifying the brightness of optical components.

[0088] Finally, the description of the light diffusion (étendue) of the rotationally symmetric plane aperture (Aperture) of the illumination system is applicable, such as Figure 26 As shown. When the refractive index is equal, it is: ⅮinSINin=ⅮoutSINout, This shows that there is a trade-off between angle and area.

[0089] In other words, reducing the angular distribution to form a collimated beam expands the space, while focusing the light increases the angular distribution but shrinks the space, which remains constant. Therefore, once the image display area S1 of the LCOS panel, which receives light, is determined, the capture angle is also determined.

[0090] Therefore, this invention realizes an optical component based on a new design concept, namely, a single light source unit is realized by overlapping the focal position of the reflective optical element 11 on the optical axis, and the optical component constituted by it is not subject to the invariance of isoluminance (Etendue).

[0091] While various embodiments have been described in detail above, the present invention is not limited to these embodiments and encompasses a variety of variations. For example, the entire system has been described and explained in detail in the above embodiments for easier understanding, but the present invention is not limited to products that necessarily include all of the components described.

[0092] In addition, some parts of the embodiments may be replaced by parts of other embodiments, or parts of one embodiment may be combined with parts of other embodiments. Furthermore, parts of the parts of each embodiment may be added, deleted, or replaced by other parts.

[0093] Control of the diffusion and directional characteristics of light emitted from the liquid crystal panel: In a conventional television application device, the light emitted from the liquid crystal display panel, e.g. Figure 24A "Traditional Characteristics (X Direction)" and Figure 24B As shown in the curve of "Conventional Characteristics (Y Direction)", in the horizontal direction of the screen ( Figure 24A The X-axis of the middle curve corresponds to the display direction) and the vertical direction of the screen ( Figure 24B In the display direction corresponding to the Y-axis of the middle curve), it has similar diffusion characteristics.

[0094] In comparison, the diffusion characteristics of the light beam emitted by the liquid crystal display panel of this embodiment are as follows: Figure 24A "Example 1 (X direction)" and Figure 24B The curve of "Case 1 (Y direction)" shows the diffusion characteristics.

[0095] In a specific example, when the viewing angle is set to 13 degrees at 50% brightness (approximately half the brightness) relative to frontal viewing (angle of 0 degrees), this viewing angle is approximately one-fifth the scattering characteristics of a typical home television (angle of 62 degrees). Similarly, in the case of uneven vertical viewing angles, the upper viewing angle can be reduced to approximately one-third (narrowed) of the lower viewing angle by optimizing the reflection angle and reflection area of the reflective light guide.

[0096] By setting the field of view angle as described above, the amount of image light directed in the user's viewing direction (the user's line of sight) is significantly increased (the image brightness is significantly improved) compared to traditional LCD TVs, with the brightness of the related image reaching more than 50 times.

[0097] Furthermore, in the case of the viewing angle characteristics shown in "Example 2" in Figure 24, when the viewing angle is set to 5 degrees, where the brightness is 50% (brightness is reduced by approximately half) when viewed from the front (angle 0 degrees), the viewing angle is approximately 1 / 12 of the diffusion characteristics (angle 62 degrees) of a typical home television set (a narrow viewing angle). Similarly, in an example where the vertical upper and lower viewing angles are set equally, by optimizing the reflection angle and reflection area of the reflective light guide, the vertical viewing angle can be controlled (narrowed) to approximately 1 / 12 of that of conventional methods.

[0098] By making this setting, the image brightness (amount of light) in the viewing direction (the direction of the user's line of sight) is significantly improved compared to traditional LCD TVs, with the brightness of the relevant image reaching more than 100 times.

[0099] Optical component design suitable for narrow-divergence image light: As previously mentioned, by narrowing the field of view, the light beam is concentrated within the optical component. Therefore, using the aforementioned image source optical component not only significantly improves the efficiency of image light utilization, but also ensures that the image light beams emitted from each image source have a narrow divergence angle and high light energy density. Consequently, even with a small-aperture optical component, sufficiently bright real or virtual images can be obtained. Aberrations generated by small-aperture optical components are minimized, making correction easier and achieving bright, high-resolution magnified images. As a result, a low-power, high-definition, high-brightness magnified image display device can be realized using a small number of lenses and concave mirrors.

[0100] When using a large-size LCD panel as an image source, it is best to direct the light surrounding the image when the center of the screen faces the viewer inward, toward the optical components, to increase overall screen brightness. Alternatively, when the image display device has a panel size (16:10 aspect ratio) of 3 inches or less, the LCD panel described in this embodiment can be used in portrait orientation (hereinafter referred to as "portrait orientation"), significantly narrowing the horizontal directional characteristic angle, thereby achieving a high-brightness or low-power image display device.

[0101] In addition, through the above light source device, Figure 24A and 24B Compared to the conventional liquid crystal display panel's light diffusion characteristics (referred to as "conventional characteristics" in the figure), the angles of the directional characteristics in the X- and Y-axis directions can be significantly narrowed. In this embodiment, by having such narrow-angle directional characteristics, an image display device can be realized that emits nearly parallel image beams in a specific direction, emitting light of a specific polarization with a narrow divergence angle.

[0102] The second information display device of the vehicle information display system: As described above, Figure 3(This is an embodiment of a second vehicular information display system with a narrow-divergence, high-efficiency light source device.) A specifically polarized image beam, generated by a compact, lightweight, narrow-divergence, high-brightness image display device 4, is reflected off the windshield 6, allowing the driver to see a virtual image. Due to the aforementioned light source device, the information display device of this second embodiment boasts high light conversion efficiency and low power consumption. It can be powered by a portable battery and, when needed, placed on the dashboard 42. By adjusting its orientation and height relative to the windshield 6, it can be positioned optimally for the driver's viewing position.

[0103] When sunlight enters the vehicle, it reflects S-polarized light after passing through the windshield 6, leaving almost all of it as P-polarized light. The polarizers placed on the incident surface of the LCD panel are typically absorbing polarizers, which absorb P-polarized light. Therefore, placing an optical film or glass that reflects P-polarized light on the windshield side of the absorbing polarizer can significantly improve the reliability of components such as the LCD panel.

[0104] When using the LCD panel described in this embodiment as a device for emitting image light with specific polarization, the brightness of the image light decreases significantly when using polarized sunglasses due to the high surface reflection. To address this issue, a polarization canceling element is attached to the output surface of the LCD panel, converting the image light into a mixture of P- and S-polarization light. This allows drivers to obtain a sufficiently bright virtual image even when wearing polarized sunglasses.

[0105] Various embodiments or examples (i.e., specific examples) to which the present invention is applied have been described in detail above. On the one hand, the present invention is not limited to the above-mentioned embodiments (specific examples), but also includes various modified examples. For example, the above-mentioned embodiments describe the entire system in detail in order to more clearly illustrate the present invention, and are not limited to having all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added, deleted, or replaced in the structure of a certain embodiment. The above-mentioned light source device is not limited to being applied to an optical system having an image source with a narrow divergence angle characteristic and a virtual image display device having the above-mentioned optical system, but is also applicable to display devices such as HUD, tablet computers, digital signage, etc.

Claims

1. An in-vehicle information display system with a solid-state light source, characterized in that: A virtual image display device is provided, wherein the virtual image display device includes an optical system, the optical system comprising an image display device for displaying an image, a light source device including a surface-emitting solid-state light source for supplying light to the image display device, and an optical component for receiving image light from the image display device; The light source device is composed of a single light source module, which is composed of a surface-emitting solid light source and an optical element that narrows the divergence angle of the divergent light beam emitted by the surface-emitting solid light source. A plurality of the single light source modules are arranged in two dimensions to form a light source unit and an image display device. The light beam from the light source unit is incident on an image display device, and the image display device adjusts the intensity of the light according to an image signal to display an image on a screen; The light source module is constructed as follows: a divergent light beam from a surface-emitting solid-state light source is reflected on a reflective surface, converted into approximately parallel light, and placed near the focal point of a reflective optical element; a cylindrical hole is designed at the focal point of an end face of the reflective optical element, and the surface-emitting solid-state light source is placed in the hole; The reflective surface of the reflective optical element constituting the aforementioned single module is in a parabolic shape, the surface-emitting solid element is designed on its end face, and the reflected light beam exit surface opposite to it is in a hexahedron shape, and adjacent single optical modules are closely arranged and seamlessly connected; The light source device comprises a light source unit composed of a plurality of two-dimensionally arranged single light source modules, and is characterized in that the diameter of the inscribed circle of the hexahedron is substantially equal to the maximum diameter of the parabolic reflecting surface.

2. The vehicle information display system with a solid-state light source according to claim 1, characterized in that: Light is provided to the image display device by the aforementioned light source device, wherein the light source device comprises a plurality of individual light source modules arranged two-dimensionally to form a light source unit, wherein holes are provided on the end faces of the individual light source modules, and the holes are approximately cylindrical along the optical axis direction including the focus of the reflective optical element, and the side surfaces of these cylinders refract a portion of the divergent light from the surface-emitting solid light source; By being reflected at different positions on the reflective surface of the aforementioned reflective optical element, the divergent light beam from the surface-emitting solid light source can be converted into a light beam with an approximately narrow divergence angle.

3. The vehicle information display system with a solid-state light source according to claim 2, characterized in that: The light source device comprises a light source unit composed of a plurality of single light source modules arranged in a two-dimensional manner; The aforementioned single light source module is provided with a hole on its end face, which is approximately cylindrical along the optical axis direction including the focus of the reflective optical element, and the side surfaces of these cylinders refract part of the divergent light from the surface-emitting solid light source; By reflecting at different positions on the reflective surface of the reflective optical element, the divergent light beam from the surface-emitting solid light source can be converted into a divergent light beam with a narrow divergence angle, and the divergent light beam diverges from multiple focal points along the optical axis of the reflective optical element.

4. The vehicle information display system with a solid-state light source according to claim 1, characterized in that: The light source device comprises a light source unit composed of a plurality of single light source modules arranged in a two-dimensional manner; A hole is provided on the end face of the aforementioned single light source module, which is roughly cylindrical along the optical axis direction including the focus of the reflective optical element. The narrow-angle divergent light beam from the surface-emitting solid light source is incident on the front end face of the cylinder and is refracted by the lens shape provided on the front end face, thereby controlling the incident position and incident angle of the light beam incident on the reflective surface of the reflective optical element.

5. An in-vehicle information display system with a solid-state light source, characterized in that: A virtual image display device is provided, wherein the virtual image display device includes an optical system, the optical system comprising an image display device for displaying an image, a light source device including a surface-emitting solid-state light source for supplying light to the image display device, and an optical component for receiving image light from the image display device; The light source device comprises a light source unit composed of a plurality of individual light source modules arranged in a two-dimensional manner, wherein the individual light source modules are composed of a surface-emitting solid light source and an optical element for narrowing the divergence angle of a divergent light beam emitted from the surface-emitting solid light source; The image display device displays an image on a screen by causing a light beam from a light source unit to be incident on the image display device and adjusting the intensity of the light according to an image signal. The light source module converts a divergent beam from a surface-emitting solid-state light source into approximately parallel light by reflecting it on a reflective surface, and places the divergent beam near the focal point of a reflective optical element. A cylindrical hole is also provided at the focal point of an end face of the reflective optical element, and the surface-emitting solid-state light source is placed in the hole. The reflective surface of the reflective optical element constituting the aforementioned single module is formed by a plurality of regions, and the first region close to the aforementioned surface-emitting solid light source is in a parabolic shape; The second reflective region is located near the end face of the surface-emitting solid-state device and the opposite reflected light beam emission surface, and has different divergence characteristics from the reflected light beam of the first reflective region. The end face of the surface-emitting solid-state device and the opposite reflected light beam emission surface have a hexahedral opening shape, and adjacent single optical modules are seamlessly connected and neatly arranged. The inner diameter of the circumscribed circle of the hexahedron of the single light source module is equal to the maximum diameter of the second reflective area.

6. The vehicle information display system with a solid-state light source according to claim 5, characterized in that: The light source device comprises a light source unit formed by a plurality of individual light source modules arranged in a two-dimensional manner. The individual light source modules are provided with holes on their end faces, which are approximately cylindrical along the optical axis direction including the focus of the reflective optical element. The side surfaces of these cylinders refract a portion of the divergent light from the surface-emitting solid light source. The divergent light beam of the surface-emitting solid light source is converted into a light beam having a divergent angle of approximately narrow angle by reflection through the reflective surfaces at different positions of the reflective optical element.

7. The vehicle-mounted information display system with a solid-state light source according to claim 5, characterized in that: The light source device comprises a light source unit composed of a plurality of individual light source modules arranged in a two-dimensional manner. Holes are provided on the end faces of the individual light source modules, forming a substantially cylindrical shape along the optical axis direction including the focus of the reflective optical element. The side faces of these cylinders refract a portion of the divergent light from the surface-emitting solid light source. By reflecting at different positions on the reflective surface of the reflective optical element, the divergent light beam from the surface-emitting solid light source can be converted into a divergent light beam with a narrow divergence angle that diverges from multiple focal points along the optical axis of the reflective optical element.

8. The vehicle-mounted information display system with a solid-state light source according to claim 5, characterized in that: The light source device is designed with a hole on the end face of the aforementioned single light source module, which is approximately cylindrical along the optical axis direction containing the focus of the reflective optical element. After the narrow-angle divergent light beam in the divergent light beam from the surface-emitting solid light source enters the front end face of the cylinder, it is refracted by the lens arranged on the front end face.

9. The vehicle information display system with a solid-state light source according to claim 5, characterized in that: Among the light beams emitted by the aforementioned single light source module, the reflected light beams from the second reflection area in the side reflection area of the aforementioned reflective optical element diverge toward the image display device, and the divergent lights from multiple adjacent single light source modules overlap on the light incident surface of the image display device.

10. The vehicle-mounted information display system with a solid-state light source according to any one of claims 1 to 5, characterized in that: The light source device comprises a light source unit composed of a plurality of single light source modules arranged in a two-dimensional manner, wherein the single light source modules are formed of heat-resistant plastic material.

11. The vehicle information display system with a solid-state light source according to claim 10, characterized in that: In the light source device, a single light source module is made of heat-resistant plastic with a heat-resistant temperature of more than 120 degrees.

Images