CN118011643A - Image display device with virtual image mode - Google Patents
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Abstract
The invention discloses a virtual image mode image display device, comprising a light source device which is provided with a display panel for displaying images and a surface light emitting element for supplying light to the display panel, wherein the light source device is provided with the surface light emitting element arranged between the surface light emitting element and the display panel and an optical element for reducing the divergence angle of divergent light beams from a surface light source; the divergent light beam is controlled in the direction of propagation inside the optical element by the shape of the light incident surface of the optical element, and the diffusion angle and the emission position of the light beam to the display panel can be controlled by designing the lens shape on the light emitting surface of the optical element. The present invention improves the efficiency of the image light entering the optical assembly by controlling the intensity and diffusion characteristics of the image light emitted from the image display surface of the display panel as an image display device, forming an enlarged projected image.
Description
Technical Field
The present invention relates to an information display system for projecting an image onto a front windshield or a combination screen of an automobile, a train, an airplane, or the like (hereinafter, collectively referred to as a "vehicle"), and a vehicle information display device for observing a real image or a virtual image of the projected image by turning back the projected image of the system through the front windshield, as well as observing an image reflected by a mirror. The vehicle information display system and the image source in the information display device use a light source device having an optical element, and the optical element in the light source device can control the divergence characteristic of light emitted from a plurality of surface light sources arranged together, thereby greatly improving the light utilization efficiency.
Background
In a known vehicle information display system (Head-Up DISPLAY DEVICE), an image of an image source is enlarged by a concave mirror and provided to a driver through a front windshield. The light emitted from the image source used in this information display device is entirely diffused light, and in order to sufficiently secure the brightness of the enlarged image in the projection optical system having the concave mirror, it is necessary to use a large concave mirror disclosed in patent literature (JP 6540988B2, 2019.07.10) to capture a wide range of diffused image light beams.
In an optical system that enlarges an image displayed by an image source using a concave mirror and obtains a virtual image, a conventional image source, such as an organic EL (Electric Luminescent), image light emitted by an organic EL is completely diffused, and thus in order to capture all the image light, a large-caliber concave mirror is required. In addition, in order to achieve a large aperture and a good focusing performance of the virtual image optical assembly having the concave mirror, a plurality of concave mirrors or a combination of lens elements are required.
However, in the optical component design for obtaining a magnified image of a virtual image using the concave mirror of the above-described conventional technique, the diffusion characteristics and the directivity characteristics of the image light emitted from the image source, and the construction and implementation techniques of an optimal optical system including these characteristics are not considered.
Disclosure of Invention
The invention provides an optical component structure capable of improving light utilization efficiency and its realization technology. In the optical assembly for obtaining an enlarged virtual image using a concave mirror, the light utilization efficiency is improved by optimizing the emission direction and diffusion characteristics of image light emitted from an image source without increasing the aperture of the optical assembly or the number of lenses.
In order to solve the above problems, the present invention provides an image display device of a virtual image system, the image display device of the virtual image system including an optical system, the optical system including: a light source device for displaying an image, the light source device having a surface light emitting element for supplying light to the display panel,
The light source device includes, as a light source, a surface light emitting element arranged between the surface light emitting element and the display panel, and an optical element for reducing a divergence angle of a divergent light beam from a surface light source;
the divergent light beam is controlled in the direction of propagation inside the optical element by the shape of the light incident surface of the optical element, and the diffusion angle and the emission position of the light beam to the display panel can be controlled by designing the lens shape on the light emitting surface of the optical element.
Further, the optical element includes a reflection surface as a final surface, and the amount of light of the image light receiving optical element emitted from the image display surface of the display panel is determined by the light diffusion characteristic of the light source device.
Further, the aforementioned optical system includes a reflection surface as a final surface, displays an image displayed on the display panel as a virtual image,
The diffusion characteristic and the emission direction of the image light emitted from the image display surface, and the amount of received light by the optical element can be controlled by the diffusion characteristic of the light source device.
Further, the light source device includes a surface light emitting element as a light source, and an optical element capable of reducing a diffusion angle of a divergent light beam from the surface light source is disposed between the surface light emitting element and the display panel;
The light incident surface shape of the optical element can control the propagation direction of the diffused light beam in the optical element; the spread angle and the incidence position of the light beam emitted onto the display panel are controlled according to the designed lens shape on the light emitting surface of the optical element.
Further, the light source device includes a surface light emitting element as a light source, and the optical element capable of reducing a spread angle of a divergent light beam from a surface light source is disposed between the surface light emitting element and the display panel;
the direction in which the diffused light beam propagates inside the optical element can be controlled by the shape of the entrance surface of the optical element; the optical element is made of plastic material or glass material, and controls the diffusion angle and incidence position of the light beam emitted onto the display panel according to the lens shape on the emitting surface.
Further, the light source device includes a surface light emitting element as a light source, an optical element disposed between the surface light emitting element and the display panel, for reducing a spread angle of a divergent light beam from a surface light source, and a direction in which the divergent light beam propagates inside the optical element is controlled by an incident surface shape of the optical element, and a spread angle and an incident position of the light beam emitted onto the display panel are controlled by a lens shape and an decentered shape of a lens designed on an emitting surface of the optical element.
The present invention also provides an image display device for diffusing an image light beam at a narrow diffusion angle, wherein the image display device includes a display panel for displaying an image and a light source device for supplying light to the display panel, the light source device includes a surface light emitting element as a light source, and an optical element for reducing a diffusion angle of a divergent light beam from a surface light source is provided between the surface light emitting element and the display panel, and an optical system for reflecting the image light from the display panel to generate a virtual image toward an image viewer is provided as a final surface, the reflection surface of the image display device being not in the same housing.
The obtained image light forming virtual image is formed by the optical system receiving the image light from the display surface of the display panel image, and is controlled by the diffusion angle of the image light from the display panel of the light source device,
The image beam obtained at the screen center of the aforementioned enlarged virtual image is blocked by the pupil of the virtual image viewer forming the aforementioned optical system.
The optical module is an oblique projection optical module having an elevation angle with respect to the display panel, and the oblique projection optical module is an optical module capable of obtaining a virtual image that is approximately equal to an image displayed on the display panel, and includes a light source device capable of adjusting an incident position and an incident angle of image light emitted from the image display device and entering a final surface (a reflection surface outside the housing) of the optical module.
Further, an optical sheet for mixing polarization directions of image light of a specific polarization is attached to the image light exit surface of the display panel.
Further, the optical element includes a concave mirror and an optical element for controlling an angle at which the image light diverged from the display panel enters the optical element, and is an optical element for obtaining a virtual image from an image displayed on an image display surface of the display panel;
the amount of image light received by the optical module from the display panel is determined by the diffusion characteristic of the image light from the display panel obtained by the light diffusion characteristic of the light source device.
The present invention also provides a virtual image system image display device including an optical system including: a display panel for displaying an image, the light source device for supplying light to the display panel, the optical module for receiving the image light emitted from the display panel, and the optical element having a light incident surface of the display panel;
The diffusion characteristics of the image light emitted from the display panel are different in the long side direction and the short side direction of the display panel;
The optical element has an effect of adjusting the direction of the image light emitted from the display panel to the optical module, and is a virtual image mode image display device capable of adjusting the incidence position and incidence angle of the image light emitted from the optical element to the optical module.
Further, the diffusion characteristic of the image light emitted from the display panel is adjusted by the diffusion characteristic of the light beam emitted from the light source device to the display panel, and is different between the long side and the short side of the display panel;
the divergence angle of the image light in the long side direction of the picture emitted by the display panel is larger than that in the short side direction of the picture.
The technical scheme adopted by the invention has the beneficial effects that:
The invention can control the emitting direction of the image light with the light intensity modulated according to the image signal of the image display device, and can also control the incident position and the incident angle of the incident image light entering the rear-stage optical assembly. In this optical system, therefore, the efficiency of the image light entering the optical assembly can be improved by controlling the intensity and diffusion characteristics of the image light emitted from the image display surface serving as the display panel of the image display device, forming an enlarged projected image.
According to the present invention, as a light source device of an image display device, by controlling the directivity and diffusion characteristics of image light, in the design of an optical component for obtaining an enlarged virtual image using a concave mirror, by considering the diffusion characteristics of image light emitted from the image display device, the performance of the optical component is improved, and a cost-effective optical component can be realized. The basic structure, design concept and effect of the optical assembly for controlling the enlarged virtual image and the image display device for controlling the emission direction and diffusion characteristic of the image light, and the light source device used therefor will be described based on the following embodiments.
Drawings
Fig. 1 is a schematic configuration diagram of an information image apparatus and peripheral devices thereof according to an embodiment of the present invention;
Fig. 2 is a schematic configuration diagram of an information display device, a front windshield, and a driver viewpoint position according to an embodiment of the present invention;
Fig. 3 is a schematic configuration diagram of an information display device, a front windshield, and a driver viewpoint position according to another embodiment of the present invention;
fig. 4A is a top view of an automobile equipped with an information display device;
Fig. 4B is a diagram illustrating a difference in radius of curvature of the front windshield;
fig. 5 is a characteristic diagram illustrating diffusion characteristics of the surface-emission LED light source;
fig. 6 is a schematic configuration diagram of a light source device according to an embodiment of the present invention;
Fig. 7 is a schematic view of luminance distribution on a screen display surface of an information image display apparatus obtained by a light source apparatus relating to one embodiment of the present invention;
Fig. 8 is a schematic configuration diagram of a light source device according to another embodiment of the present invention;
fig. 9 is a schematic plan view of a luminance distribution on a screen display surface of an information image display device obtained by a light source device relating to other embodiments of the present invention;
Fig. 10 is a conceptual sectional view illustrating the function of an optical element constituting a light source device relating to the present invention;
Fig. 11 is a conceptual sectional view illustrating the function of an optical element constituting a light source device relating to the present invention;
fig. 12 is a conceptual sectional view illustrating the function of optical elements constituting the light source device relating to the present invention;
Fig. 13 is a conceptual sectional view illustrating the function of an optical element constituting a light source device relating to the present invention;
fig. 14 is a conceptual sectional view illustrating the roles of optical elements constituting a conventional light source device;
fig. 15 is a conceptual sectional view illustrating the roles of optical elements constituting a conventional other light source device;
Fig. 16A is a coordinate system explanatory diagram of visual characteristics of a liquid crystal panel as an image source in relation to one embodiment of the present invention;
Fig. 16B is a view illustrating visual characteristics of a liquid crystal panel as an image source according to an embodiment of the present invention;
fig. 17 is a view illustrating the diffusion characteristics of the light source device of the present invention;
fig. 18A is a view illustrating visual characteristics of a liquid crystal panel as an image source in accordance with an embodiment of the present invention;
fig. 18B is a view illustrating visual characteristics of a liquid crystal panel as an image source according to an embodiment of the present invention;
Fig. 19 is a diagram illustrating a measurement coordinate system of visual characteristics of a liquid crystal panel as an image source in accordance with an embodiment of the present invention;
fig. 20 is a view showing luminance angle characteristics (longitudinal direction) of a general liquid crystal panel;
Fig. 21 is a view of luminance angle characteristics (width direction) of a general liquid crystal panel;
fig. 22 is a contrast angle characteristic (lengthwise direction) diagram of a general liquid crystal panel;
fig. 23 is a graph of contrast angle characteristics (width direction) of a general liquid crystal panel;
FIG. 24A is an illustration of the design environment for an optical assembly structure and an optical assembly including a concave mirror in accordance with one embodiment of the present invention;
Fig. 24B is an explanatory view showing a variation in the amount of aberration caused by a projection lens constituting an optical assembly or an optical assembly with a concave mirror according to the diffusion characteristic of image light in accordance with an embodiment of the present invention;
fig. 25 is a schematic explanatory diagram of a virtual image optical system using a concave mirror in accordance with an embodiment of the present invention.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the 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 relates to the scope and equivalents of the technical ideas described in the spirit of the invention or the claims. Further, the configuration of the embodiment (embodiment) described below is only an example, and various changes and modifications may be made by those skilled in the art within the scope of the technical ideas disclosed in the present specification.
In the drawings for explaining the present invention, the same or similar functional elements are denoted by the same reference numerals, and, if appropriate, the description of duplicate functions and the like will be omitted even if the names used are different.
In the following description of the embodiment, the term "enlarged virtual image" is used for a virtual image formed in the air by an optical element using a concave mirror. And the term "magnified real image" is used for a real image formed in space using an optical assembly having a positive refractive power or a convex lens. These terms may also be expressed in terms of "magnified image", "virtual image", "real image", and the like. In describing the embodiments, the term "enlarged virtual image" is mainly used, and this term is used as a representative example of these terms.
The present invention relates to an optimum design method of an optical component for displaying an image of a compact image light-emitting source generating an image beam of a narrow divergence angle in the form of an enlarged image of a virtual image or a real image, and an embodiment of the virtual image optical component obtained thereby and an optical system to which the same is applied. According to the present invention, in an optical module for obtaining an enlarged real image using a projection lens and an optical module for obtaining an enlarged virtual image using a concave mirror, by optimally designing the optical module in consideration of the diffusion characteristics of image light emitted from an image source, the aperture size of the optical module can be reduced, the number of lenses and mirrors can be reduced, and a high cost performance optical module structure can be obtained. In particular, since the luminance of the amplified virtual image is equal to the luminance of the light source, it has excellent light energy conversion efficiency.
Fig. 4A is a top view of an information display device 1000, 1001 according to an embodiment of the present invention mounted on a vehicle such as an automobile, a train, or an airplane. In front of the driver's seat of the automobile 1010, there is a front windshield 6 as a projection member. The angle of inclination of this front windshield 6 with respect to the vehicle body varies depending on the type of vehicle. In addition, the inventors have investigated the radius of curvature of the virtual image optical element in order to achieve an optimal virtual image optical element. As a result, as shown in fig. 4B, it was found that the radius of curvature of the front windshield 6 is different from the radius of curvature Rh in the horizontal direction and the radius of curvature Rv perpendicular to the horizontal axis with respect to the ground plane of the automobile, and the following relationship is generally satisfied therebetween:
Rh＞Rv
in addition, these differences in radius of curvature, i.e., the ratio of Rh to Rv, were also found to be generally in the range of 1.5 to 2.5 times.
In the invention, the image information is reflected and displayed by the front windshield of the driver observing the external scenery during driving. The information display device enables the optical component of the head-up display device to effectively capture the incident light beam by emitting the image light beam at a narrow divergence angle and adjusting the emitting direction according to the picture position, thereby providing a high-brightness virtual image which can be properly displayed.
The head-up display device according to one embodiment is an information display device that displays a virtual image on a projection surface, and includes an image light generating unit that generates display image information and a light source unit that supplies light to the image light generating unit, inside a casing having a portion of a opening. The light source device is provided with an optical element capable of converting light generated by a surface light source into light of a desired divergence angle between the surface light source and an image display device (liquid crystal panel), and has means for controlling the divergence angle and the directivity characteristic.
Fig. 1 is a schematic view showing the configuration of peripheral devices of a first information display device of a vehicle information display system according to the present invention. Here, an information display device 100 that projects an image onto a front windshield 6 of an automobile will be described as an example thereof. The head-up display device of the information display device 100 is an embodiment of the present invention, and the image display device 104 modulates the light-matching image signal emitted from the light source device 102 to display an image, and projects this image in the form of a virtual image into the line of sight (viewpoint to be described later) 8 of the driver through the concave mirrors 105 and 106 to form a virtual image V1 and display it in front of the vehicle. Is a device (so-called HUD (Head-Up Display)) that displays various information reflected by a projection member (in this embodiment, the inner surface of the front windshield 6) in the form of a virtual image VI (Virtual Image). The control device 40 constituting the HUD is illustrated to acquire, as foreground information (i.e., the information displayed in front of the vehicle by the virtual image) from the navigation system 61, various information such as the speed limit of the road corresponding to the current position of the vehicle, the number of lanes, the planned travel route of the vehicle provided in the navigation system 61, and the like.
In the second information display device 101 of the information display device for a vehicle according to the present invention, the reflected image (virtual image) is obtained by projecting the light emitted from the high-luminance light source having a narrow diffusion angle, which is modulated by the video display device 103 in accordance with the video signal, onto the front windshield 6 of the vehicle. Since the concave mirror is not used, miniaturization can be realized, and a plurality of image information can be observed at the same time by being mounted in parallel with the first information display device.
Further, the illustrated driving assistance ECU 62 is a control device that controls the drive system and the control system based on the obstacle detected as a result of the monitoring by the surroundings monitoring device 63 to realize driving assistance control. Such driving assist control includes well-known technologies such as cruise control, adaptive cruise control, pre-crash safety system, lane keeping assist, and the like.
The illustrated surroundings monitoring apparatus 63 is an apparatus that monitors the surrounding situation of the host vehicle, such as a camera that detects an object existing around the host vehicle based on an image of the surrounding of the host vehicle, or a detection apparatus that detects an object existing around the host vehicle based on the result of the transmitted and received detection waves.
The control device 40 of the HUD device described above acquires the foreground information from the information (for example, the distance to the preceding vehicle and the azimuth of the preceding vehicle, the position of an obstacle or a sign, etc.) obtained from the driving assistance ECU 62. The control device 40 also receives an Ignition (IG) signal and own vehicle state information. The present vehicle state information is information acquired as vehicle information, and does not require high-resolution display, and includes display of abnormality warning information that has been specified in advance, such as the remaining amount of fuel and the cooling water temperature associated with internal combustion. Further, the operation result of the direction indicator, the running speed of the own vehicle, shift position information, and the like are included. The control device 40 is activated when receiving the IG signal. The above is a description of the overall system of the information display device of the present embodiment.
The projected member may be any member for projecting information, and may be other members, such as a combination screen, as well as the front windshield 6 described above. In other words, the information display device 100 of the present embodiment may be configured to form a virtual image in front of the vehicle so that the driver can see the virtual image in the line of sight 8.
In the information display device 100 having the above-described structure, image light of display information projected by the image display device 104 forms a virtual image by concave (free-form surface) mirrors 105 and 106, and corrects the formed distortion and aberration in the shape of the two mirrors. The image beam emitted from the information display device 100 is directed from an opening (not shown) to the front windshield 6.
Further, as a second embodiment of the information display device 100, as shown in fig. 1, the display image of the image display device 103 may be directly reflected into the line of sight of the driver. The construction and function of which will be described in detail below with reference to fig. 3. The image display device 4 has a control device 40 (not shown) that controls backlight. In addition, in the foregoing first embodiment, the optical components including the image display device 104, the backlight 102, and the like are a virtual image optical system, which will also be described below, which includes the concave mirror 1 that reflects light. On the other hand, the second embodiment reflects the display image of the image display device 4 directly onto the front windshield 6 and toward the driver's line of sight 8.
As shown in fig. 1, the image display devices 103 and 104 and the image display device 4 shown in fig. 3, for example, an LCD (Liquid CRYSTAL DISPLAY) having a backlight, may use a self-luminous device VFD (Vacuum Fluorescent Display).
On the other hand, as shown in fig. 2, the image of the image display device 403 may be reflected as a virtual image by the concave mirror 1a toward the viewpoint 8 of the driver via the front windshield 6 or a combination screen (not shown) which is a projected member.
Here, in order to reduce distortion of the virtual image, the shape of the concave mirror 1a is such that the upper portion (light reflection region below the front windshield 6 which is relatively short from the viewpoint 8 of the driver) has a smaller relative radius of curvature and thus a larger magnification, and the lower portion (light reflection region above the front windshield 6 which is relatively long from the viewpoint of the driver) has a relatively larger radius of curvature and thus a relatively smaller magnification, as shown in fig. 2. Further, the image display device 4 is inclined with respect to the optical axis of the concave mirror 1a, and the difference in the virtual image magnification can be corrected, thereby reducing distortion to achieve a better correction effect.
On the other hand, in the front windshield 6 of the passenger car, as shown in fig. 4B, the curvature radius Rv in the vertical direction and the curvature radius Rh in the horizontal direction of the main body are different, and generally Rh > Rv. Therefore, if the front windshield 6 is regarded as a reflecting surface, it is the same as the concave surface of the concave mirror 1. Therefore, in the information display device 100 of the present embodiment, the shape of the concave mirror 1 should correct the virtual image magnification according to the shape of the front windshield, that is, employ different average radii of curvature in the horizontal and vertical directions to correct the difference in radii of curvature in the vertical and horizontal directions of the front windshield 6.
Therefore, the designers can define the shape of the surface as a function of the absolute coordinates (x, y) of the optical axis by using the free-form surface shape (see the formula of the following number 1) in comparison with the conventional optical design in which the lens and mirror surface shapes are defined as a function of the distance r to the light axis using the aspherical shape (see the formula of the following number 2), thereby reducing the problem of deterioration of the image forming performance of the virtual image due to the difference of the curvature radius of the front windshield described above.
[ Number 1]
In addition, the aspherical shape defining the shape of the lens surface or the reflecting mirror surface as a function of the distance r from the optical axis can be expressed by the following formula of number 2.
[ Number 2]
In this case, the concave mirror 1 is formed as a spherical or aspherical surface (hereinafter, referred to as "number 2") symmetrical about the optical axis, and is a function of the distance r from the optical axis, and since the horizontal cross section and the vertical cross section at a distance cannot be controlled independently, it is preferable to compensate the free curved surface shown by "number 1" with a function of coordinates (x, y) of the surface of the reflecting mirror surface with respect to the optical axis.
According to the following embodiment, for example, as shown in fig. 25, an enlarged image BB' of high resolution can be displayed behind the concave mirror, in which case the concave mirror can be made to efficiently reflect only normally reflected light by reducing the scattering angle of the image light emission to an acute angle and adjusting to a specific polarization.
In the case of using a liquid crystal display panel (liquid crystal panel or display panel) as an image display device for obtaining image light of a specific polarization, a polarization cancellation element may be provided on a surface of the liquid crystal panel on the observer side, that is, on the optical module side, and a part of the image light may be converted into polarization in other directions by optical conversion to be converted into pseudo natural light. In this way, even if the observer wears the polarized sunglasses, an enlarged image of a virtual image of high quality can be viewed.
Commercially available products of the polarization eliminating element include CosmoShine SRF (manufactured by TOYOBO Co., ltd.) and a polarization eliminating adhesive (manufactured by Datagram Co., ltd.). CosmoShine SRF (manufactured by Toyo textile Co., ltd.) to reduce interface reflection and improve brightness by applying an adhesive to an image display device. In addition, when a polarization releasing adhesive is used, it can be applied as an adhesive between an image display device of a liquid crystal panel and a colorless transparent plate. In the present embodiment, as described above, the image display device includes the liquid crystal display panel 11 and the light source device 13 generating light of a specific polarization with a narrow angle diffusion characteristic, and therefore, efficient use of light can be achieved, and an optical system which can view an enlarged virtual image outdoors, which cannot be achieved by the conventional virtual image technology, can be obtained, which is achieved by a low-power-consumption, portable small-sized image display device.
In addition, by the light source device and the optical assembly of the present disclosure, the power consumption can be greatly reduced. By combining a novel small-sized image display device (liquid crystal display panel), an enlarged virtual image display system with low power consumption and portability can be provided. According to the technology of the present disclosure, it is possible to provide an image display device capable of realizing, for example, a one-way enlarged virtual image visible from a specific direction inside a vehicle, that is, capable of being displayed through a windshield, a rear-view glass, and a side glass of the vehicle.
Next, as embodiments of the present disclosure, description is made of an effect of an optical system that obtains an enlarged virtual image and embodiments of specific optical systems. Fig. 25 shows a basic structure of an optical system that obtains an enlarged virtual image. An object (AA ') is placed on the mirror surface side of the focal point F of the concave mirror 1'.
At this time, PB "/AA '=pf/af=f/(f-a), PB" =bb', and therefore, is substituted into formula (1): BB '/AA' =f/(f-a) (1)
Due to the similarity of ΔPA "F and ΔBB' F
BB′/PA″＝BF/PF＝(b+f)/f(2)
Because PA "=aa', so: BB '/AA' = (b+f)/f,
Since the left side of equation (1) and equation (2) are the same, we get:
(f/(f-a))＝(b+f)/f
f2＝(b+f)(f-a)
f2＝bf+f2-ab-af
0=bf-ab-af, dividing the above formula by abf:
(bf/abf)-(af/abf)＝(ab/abf)
(1/a)-(1/b)＝(1/f)(3)
definition of coordinates of the optical component yields (3):
(1/a)+(1/(-b))＝(1/f)
At this time, the magnification m of the virtual image is: =b/a
Therefore, by decreasing the object-to-concave mirror distance b (object point distance) and increasing the concave mirror-to-virtual image distance, i.e., image distance, a virtual image of high magnification can be obtained.
In an optical system using the virtual image optical element described above, in order to shorten the distance from the object point AA 'to the concave mirror 1', the focal length f must be shortened. However, in order to shorten the focal length, the refractive power of the concave mirror must be increased, and by the conventional optical design method, aberration at the enlarged virtual image is increased, thereby causing the enlarged virtual image to be blurred.
A new design method of a small-sized, high-luminance, and high-resolution virtual image magnification optical assembly will be described based on the following drawings, and fig. 16A, 16B, and 17 are explanatory diagrams for explaining scattering characteristics of image light emitted from the center of a display screen of an image display device. These explanatory diagrams are for explaining scattering characteristics when the liquid crystal panel 104 is used as a display element of an image display device. Fig. 16A shows an oblique view after the light emitting surface of the liquid crystal panel 11 is mounted upward. For convenience of the following description, the longitudinal direction of the screen is defined as the X-axis, the short direction is defined as the Y-axis, and the direction perpendicular to the XY-plane is defined as the Z-axis, as in the coordinate axes of fig. 19. In describing the scattering angle of image light, the Z axis will be the axis showing the relative brightness.
FIG. 24A shows a basic design environment for use in designing an optical system. The liquid crystal panel is defined as an object plane, a line segment connecting the center of the screen and the center of the entrance pupil of the optical component is defined as a Z axis, and the liquid crystal panel is disposed on a plane (XY plane) perpendicular to the Z axis. In the optical system design, for example, light is emitted from an object point Pa at the center of a screen to the current coordinates of the relative pupil height (Y-axis, -1.0 to +1.0, x-axis, -1.0 to +1.0) of the entrance pupil as a virtual plane, and the shift amount of the principal light on the XY plane from the end point 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 an aberration amount, and the optical system design is performed such that the aberration becomes zero.
The parameters of conventional optical element design include the position and shape of the liquid crystal panel as an object point and the optical element between the magnified virtual images as an image plane, and refractive index, and in the virtual image optical element using a concave mirror, the position and shape of the concave mirror are main design parameters. Further, since the pupil diameter of the human eye varies depending on the amount of incident light entering the retina (pupil diameter varies between 4mm and 8mm depending on the amount of incident light entering the retina), unnecessary light can be blocked, and image light exceeding the distance from the image plane to the viewer and the pupil diameter coverage angle cannot reach the retina, it is necessary to sufficiently consider the action of the retina of the human eye as a light blocking material when designing the optical module.
In the present invention, a liquid crystal panel is used as an image display device, and the diffusion characteristics of a light source device are made to exhibit a narrow angle, and the diffusion of image light is adjusted by the shape and surface roughness of a reflective light guide of the light source, as a new optical component design parameter. In the embodiment of the present invention described below, the diffusion characteristic of the picture level (long direction) is designed to be ±9 degrees at 50% relative luminance and ±16 degrees at 0% relative luminance; the diffusion characteristic in the vertical direction (width direction) of the screen is designed to be ±7.5 degrees at 50% relative brightness and ±13 degrees at 0% relative brightness. An optical component that emits an image beam from an object point Pa in the center of the screen is shown in fig. 24A, and coordinates corresponding to the relative pupil height and the induced aberration are shown in fig. 24B (1). The aberration generating region of the image beam generated by the image light source of the present invention is a B range, which is closer to the principal ray than an a range corresponding to the divergence angle of the beam required to obtain the same brightness in the conventional design, and thus the aberration generating amount itself is greatly reduced.
Further, as shown in fig. 24B (2), as for the image light beam emitted from the object point Pb around the screen, as well as the aberration in the meridian cross-section direction shown in fig. 24B (2) and the aberration in the sphere cross-section direction shown in the following figure, the aberration generating area of the image light beam generated by the image light source of the present invention having the narrow divergence angle diffusion characteristic is the B range, and therefore, is closer to the principal ray than the a range corresponding to the beam divergence angle required to obtain the same brightness in the conventional design, and therefore the aberration generating amount itself is greatly reduced.
In the conventional optical system, if the aberration correction capability is insufficient, it is possible to obtain good focusing performance by optimizing the diameter of a barrel for fixing lens elements constituting an optical assembly, determining the effective diameter of a lens by configuring a lens group, adjusting the width of a picture-center imaging light beam to determine the brightness (F value), and shielding a portion where the aberration is large. Further, for a light beam imaged around a screen, an effective diameter of a lens is determined by the configuration of a lens group, and focusing performance which is not problematic in practical use is obtained by blocking a large portion of light of aberration. On the other hand, in order to ensure sufficient brightness in the center of the screen and around the screen, the number of transmitted light beams must be increased as much as possible.
This is because, according to the COS θ4 rule between the object plane and the enlarged projected image plane, the relative brightness of the peripheral image plane is further lowered, and therefore, it is difficult to make it equal to the central brightness of the screen.
In contrast, the optical system of the present invention as described above is provided with a light source device capable of controlling an image beam emitted from an image display device having a narrow angle scattering property to be emitted in a direction required for an optical component. Hereinafter, a light source device having a narrow angle scattering property and capable of controlling a light emitting direction and a surface light source LED (LIGHT EMITTING Diode) thereof will be described in detail.
The surface-emitting LED and the light diffusion characteristic thereof are characterized in that a yellow luminous body is coated on the surface of a blue LED, and yellow light is emitted by exciting the yellow luminous body, so that white light is generated by mixing. The light diffusion characteristic of a general white LED is that when the light emitting surface of the LED light source is directed upward, the relative brightness corresponding to the divergence angle of the light emitted from the light emitting point thereof is in a completely diffuse distribution as shown in fig. 5, and the general light source device has the following structure: in order to capture light with a large divergence angle, an optical component is generally disposed near an LED of a surface light source, and to control the diffusion characteristic and directivity of the light beam emitted from the LED more easily, the light beam emitted from the LED is first converted into a parallel light beam by the optical component (optical element), and then the diffusion characteristic and directivity characteristic are controlled by the optical element mounted between the liquid crystal panel and the optical component,
As shown in fig. 14 and 15, the optical module used in the conventional light source device is configured such that a plurality of LEDs are disposed close to the corresponding plano-convex lenses LA, respectively, so that divergent light beams emitted from the LEDs are converted into nearly parallel light, the directional characteristics of the light beams are controlled by optical elements LB and FL between the liquid crystal panel and the LEDs, and the diffusion angles of the light beams are controlled by diffusion plates DF1 and DF 2. In the conventional optical system, the incident beam angle of each optical element is large, and reflection loss increases.
In addition, the optical assembly used for the conventional light source device shown in fig. 14 and 15 is constituted by a plurality of optical members (elements) arranged. In the first conventional example shown in fig. 14, there are 5 reflecting surfaces, and in the second conventional example shown in fig. 15, there are 7 reflecting surfaces. When light is perpendicularly incident to an optical element having a refractive index of 1.5, the reflectance is 5% per surface. As described above, since the incident angle of the conventional light source device is large, the reflectance is further increased, and the average reflectance exceeds 8%. In the first conventional example, there are 5 reflective surfaces, and the reflection loss of the entire optical assembly is 40% or more. On the other hand, in the second conventional example, there are 7 reflection surfaces, and thus the reflection loss of the entire optical system is 56% or more, the reflection loss is large, and the light utilization efficiency of the light source device is greatly reduced.
First embodiment of an optical component used in the light source device of the present invention:
first, the structure and the roles of the respective parts will be described with reference to fig. 6. The optical module used in the conventional light source device has many components, large reflection loss and low light utilization efficiency. In order to solve the problem, the invention provides a structure for greatly reducing the reflecting surface. The structure and function thereof are described below.
As shown in fig. 6, the first embodiment has a reflecting surface composed of two surfaces of a light receiving surface of a cone-shaped optical element LF and a light emitting surface provided opposite to the light receiving surface, and the divergent light emitted from the LED is reduced in divergence angle by the optical element LF1, and then the direction thereof is controlled by a lens shape designed to be located on the receiving surface.
By reflection inside the optical element LF, the divergence angle of divergent light from the LED entering the light incident surface thereof can be reduced as long as the area of the light emitting surface thereof is larger than the incident surface. Therefore, although the optical element LF is described herein as a cone-shaped for convenience of explanation, other shapes capable of reducing the divergence angle of the incident light from the anti-diffusion light source are contradictory to the present invention.
In addition, in designing the reflection performance of the side surface of the optical element LF, it is necessary to optimally design the refractive index of the optical element LF and the incidence angle of the light incident side surface so that the shape thereof can reduce the divergence angle and realize total reflection without reflection loss.
The divergent light diffusion characteristic of the surface light emitting LED is completely diffused as shown in fig. 5, and in order to improve the light utilization efficiency, the most effective method is to reduce the area of the light emitting point and improve the light capturing rate of the optical component. However, since the light emitting surface is not one point, the light emitting area of the surface emitting LED having high light emitting efficiency and large power is at least 1mm 2, and the light emitting surface is not one point, and it is necessary to place the receiving surface of the optical element close to the light emitting surface of the surface emitting LED and to provide a lens shape on the receiving surface to control the light diffusion characteristic in the optical element.
Fig. 10 is a conceptual sectional view of the arrangement of the surface light source LEDs and the optical element receiving surface and the structure and function thereof in the above-described embodiment of the present invention. Fig. 11 is a conceptual diagram of a lens surface shape having different lens actions in each region, which is provided on an optical element receiving surface that receives a divergent light beam of a surface light source LED.
In order to more clearly illustrate the lens action of the respective regions of the lens surface, the refraction action of light rays upon incidence of parallel light is conceptually shown here. The area close to the LED is in the shape of a convex lens with convex surface towards the LED, and the strong light beam is refracted onto the side of the optical element LF in the area 1 (first area of the diffusion characteristic in fig. 5) close to the optical axis l, l' and is totally reflected by the inclined surface of the side optimized for the inclination angle.
According to the embodiment of the present invention, the area of the light exit surface of the optical element LF is larger than the light receiving surface thereof, so that the inclined surface inclination angle of the optical element LF is opened to the light exit surface, and the divergence angle can be reduced without reflection loss by one or two total reflections. As a result, by optimizing the angle and length of the inclined surface described above, the divergence angle of the light beam emitted from the surface-emitting LED shown in fig. 5 can be arbitrarily reduced.
Further, by increasing the radius of curvature of the region 2 (the second region of the diffusion characteristic in fig. 5) on the receiving surface of the optical element LF shown in fig. 11, which is farther from the optical axis l, l', with respect to the region 1, reducing the relative refractive power, the incident position of the inclined surface of the optical element LF is brought close to the emitting surface, and by designing the shape such that the incident angle of the inclined surface is larger than the total reflection angle calculated from the refractive index of the optical element, the divergence angle of the light flux emitted from the surface light source LED entering the region 2 is greatly reduced.
The divergent light beam of the third region of the surface-emission LED scattering characteristics shown in fig. 5 is incident on the region 3 shown in fig. 11. By making the refractive power of this region smaller than that of region 2, the refractive light is designed so as to be directly emitted from the emission surface of the optical element LF without entering the side surface portion of the optical element LF. As a result, the divergence angle of the light emitted from the optical element can be significantly reduced to 1/5 or less.
The divergent light flux of the fourth region of the surface-emission LED scattering characteristics shown in fig. 5, which has a larger divergence angle, is captured by the region 4 shown in fig. 11. The light receiving surface is designed to have a shape that diverges the light beam after refraction (negative refractive power with a divergent effect), and the divergence angle of the divergent light beam emitted from the optical element is reduced by total reflection on the side surface of the optical element LF. In order to control the divergence angle of light diverged from the surface light source LED, the receiving surface arranged near the surface light source LED at a short distance is divided into a plurality of regions, and each region is formed into a lens surface having a different refractive power while the divergence angle is reduced by the side shape of the optical element LF.
In this embodiment, the inclined surface of the side surface of the optical element LF is divided into different portions near the light incident surface and away from the light incident surface, even if the inclined surface of the side surface is divided into two or more portions, it is contradictory to the present invention.
Fig. 6 shows the result of ray tracing in the first embodiment of the present invention. As described above, the direction of the refracted light flux emitted from the surface-emission LED is controlled by the lens shape provided on the light receiving surface of the optical element LF. In the first embodiment, the side surface of the optical element LF is divided into two regions i and ii of different inclinations, and a light beam passing through a region 4 (corresponding to a fourth region in fig. 5) farthest from the optical axis shown in fig. 11 diverges through a corresponding lens, and exits toward the exit surface through total reflection of a region i near the light receiving surface of the optical element LF in fig. 10, similarly to the light RAY5 shown in the drawing.
As a result, as shown in fig. 6, the beam divergence angle after passing through the optical element can be reduced to 1/5 or less of the beam divergence angle of the surface-emission LED. At the same time, by optimizing the shape of the entrance face and the shape of the side face, the beam density on the exit face of the optical element can also be controlled. The surface of the lens LB provided on the output surface is provided with a plurality of lens surfaces, and the direction of light beam emission to the LCD and the amount of light beam emitted per unit area (corresponding to brightness) can be controlled.
The shape of the side surface portion (reflecting surface) of the optical element LF is symmetrical with respect to the central optical axis of the LED light emitting surface, and in order to obtain a desired spread angle, the basic form is to make the center of the LED light emitting surface coincide with the central axis of the optical element. However, in order to control the emission direction of the light flux with the reduced divergence angle, which will be described later, it is also possible to provide that the center of the LED light emitting surface and the center axis of the optical element LF are intentionally offset.
In the basic form, the assembly accuracy of the driving board (not shown) of the LED is ±50 μm, and in order to secure the required performance, the number of LEDs should not exceed 10 at most, and in order to secure the mass production consistency, it is confirmed that the number of LEDs is preferably controlled to about 5 by trial production in consideration of the assembly dispersion.
Lens shape of the exit face of the optical element in the first embodiment of the present invention:
The configuration and the effects obtained will be described below based on the luminance distribution of the liquid crystal panel LCD with respect to the lens shape provided on the light emitting surface of the optical element LF (pitch Pbx 2) close to the surface light emitting LED. In the first embodiment shown in fig. 6, a lenticular lens is formed on the lens LB surface on the light emitting surface of the optical element LF in the up-down direction of the drawing sheet, i.e., in the long-side direction of the liquid crystal panel, for controlling the light diffusion characteristics in the long-side direction of the liquid crystal panel.
The luminance distribution thus obtained is as shown in fig. 7, and almost uniform luminance characteristics can be obtained in the horizontal direction. As shown in the figure, the luminance distribution normalized by the peak luminance is such that the 90% luminance area covers a wide range in the longitudinal direction of the liquid crystal panel, and a uniform luminance distribution which is practically free from problems can be obtained. The area of the lowest brightness is 75% relative to the peak brightness, and the peripheral brightness also reaches a level that is not problematic for practical use. At this time, the pitch Ph of the horizontal lenticular lenses is less than 1/3 of the pitch (Pbx 2) of the lenses LB, but if it is less than 1/20, the reflection loss increases, resulting in a decrease in brightness.
Second embodiment of optical component used in light source device of the present invention:
Fig. 8 shows the result of ray tracing in the second embodiment of the present invention. As described above, the forward direction of the diverging light flux from the surface emission LED after refraction is controlled by the lens shape provided on the light receiving surface of the optical element LF. In the second embodiment, the side surface of the optical element LF is divided into two regions i and ii of different inclinations, and the light beam passing through the region 4 (corresponding to the fourth region in fig. 5) farthest from the optical axis shown in fig. 11 diverges through the corresponding lens, totally reflects through the region i near the light receiving surface of the optical element LF in fig. 10, and exits toward the exit surface similarly to the light RAY5 shown in the drawing.
As a result, as shown in fig. 8, the beam divergence angle of the light beam passing through the optical element can be reduced to 1/8 or less with respect to the beam divergence angle of the surface-emission LED. Meanwhile, by optimally designing the shape of the incident surface and the shape of the side surface, the beam density on the outgoing surface of the optical element LF can also be controlled. The surface of the lens LB provided on the output surface is provided with a plurality of lenses, so that the amount of light beam (corresponding to brightness) emitted per unit area to the LCD and the emission direction of the light beam can be controlled.
The optical element emission surface lens shape in the second embodiment of the present invention:
Regarding the lens shape provided on the light emitting surface of the optical element LF close to the surface light emitting LED, description will be made below in terms of the brightness distribution structure and effect of the liquid crystal panel. In fig. 8, the surface of the lens LB provided on the light outgoing surface of the optical element LF forms horizontal and vertical lenticular lenses in the up-down direction (i.e., in the longitudinal direction of the liquid crystal panel) and the front-back direction of the drawing sheet, while controlling the light diffusion characteristics in the long and short directions of the liquid crystal panel.
The luminance distribution thus obtained can obtain almost uniform luminance characteristics in the horizontal and vertical directions as shown in fig. 9. The area where the luminance distribution normalized with the peak luminance is 85% to 90% of the luminance covers the entire area of the liquid crystal panel, a uniform luminance distribution which is practically free from problems is achieved, and even in the area of the lowest luminance, 80% of the peak luminance is achieved, and on the peripheral luminance, a better luminance level which is practically free from problems is obtained as compared with the first embodiment, and an area which is free from abrupt luminance change is achieved, and a uniform luminance distribution is exhibited. At this time, the pitch Ph of the horizontal lenticular lenses should be 1/3 or less of the pitch (Pbx 2) of the lenses LB, and 1/20 or less will increase reflection loss, resulting in a decrease in brightness. From the simulation, it is known that the pitch Pv of the vertical lenticular lenses is in the range of 1.1 to 3.4 times the pitch Ph of the horizontal lenticular lenses, a good luminance distribution can be obtained, and further, if it is in the range of 1.3 to 2.1 times, a more excellent luminance distribution can be obtained.
Although the horizontal lenticular lens as the design shape of the lens surface in the above embodiment, and the combined structure of the horizontal lenticular lens and the vertical lenticular lens are described. However, it is also contradictory to the present invention to arrange a plurality of lenses in a matrix, and optimize the shape of each lens to obtain a good luminance distribution.
The invention controls the means of the directional characteristic through the lens surface shape:
in the first embodiment described above, the horizontal light diffusion characteristic of the liquid crystal panel is controlled by the sectional shape of the horizontal lenticular lens provided on the surface of the lens LB on the light beam outgoing surface of the optical element LF. In fig. 12 and 13, for simplicity of explanation, light rays striking the lens surface are represented by light parallel along the optical axis.
Fig. 12 is a horizontal sectional view of a horizontal lenticular lens provided on the light beam outgoing surface of the optical element LF of the first embodiment of the present invention. As described above, the ratio of the pitch Ph of the horizontal lenticular lenses to the pitch (Pbx 2) of the lenses LB provided on the light beam emitting surface of the optical element LF should be: the pitch Ph of the horizontal lenticular lenses is preferably less than 1/3 of the pitch (Pbx 2) of the lenses LB. In order to control the light emission direction, as shown in fig. 13, the optical axis of the horizontal lenticular lens is preferably set within a range not exceeding 1/3 of each pitch Ph.
When the eccentric amount exceeds 1/3 of Ph, a side portion is generated according to the eccentric amount of the lens face. The surface roughness of this side surface portion is preferably about 10 times that of the lens surface, and it is found from experiments that more than 100 times that scattering occurs on the surface to affect the target characteristics. As described above, in the embodiment of the present invention, the divergent light of the surface-emitting LED is controlled by both the receiving surface and the light emitting surface of the optical element LF.
Therefore, by disposing a polarization conversion element between the optical element LF and the liquid crystal panel in the present embodiment, the light flux is adjusted to a specific polarization direction, and as with the image light of the surface-emission laser image source, the image light having a narrow scattering angle (high direct permeability) and a specific polarization component can be obtained, and an enlarged image which is sufficiently bright and high resolution can be obtained even if a projection lens or a concave mirror having a smaller aperture is used as compared with the image display device using the conventional technique.
The performance of the liquid crystal panel of the invention:
In general TFT (Thin Film Transistor) liquid crystal panels, the brightness and contrast performance are different depending on the characteristics of the liquid crystal and the polarizing plate with respect to each other in the light emission direction. In the test under the evaluation environment shown in fig. 19, as shown in fig. 21, the luminance and viewing angle characteristics in the short side (up and down) direction of the panel are better than those in the emission angle (+5 degree in this embodiment) in which the emission angle perpendicular to the panel face (emission angle is 0 degree) is slightly deviated. This is because the characteristic of the twist light is not 0 degrees when the maximum voltage is applied in the short side (up-down) direction of the liquid crystal panel.
On the other hand, as shown in fig. 23, the contrast performance in the short side (up and down) direction of the liquid crystal panel is good in the range from-15 degrees to +15 degrees, and the most excellent performance can be obtained in the range of ±10 degrees with 5 degrees as the center in combination with the luminance characteristics shown in fig. 21.
As shown in fig. 20, the luminance and viewing angle characteristics in the long side (left-right) direction of the liquid crystal panel are preferably set at an emission angle perpendicular to the panel surface (the emission angle is 0 degrees). This is because the twisted light characteristic is 0 degrees when the maximum voltage is applied to the long sides (left-right direction) of the liquid crystal panel.
Also, as shown in fig. 22, the contrast performance in the long side (left-right) direction of the liquid crystal panel is better in the range of-5 degrees to-10 degrees, and the performance in the range of ±5 degrees centering around-5 degrees is most excellent in combination with the luminance characteristics. Therefore, the image light emitted from the liquid crystal panel is emitted at an angle, and the incident light from the liquid crystal panel is passed through the light flux direction conversion means provided in the light guide of the light source device 13 to obtain an incident direction having an optimal characteristic, and is modulated by the image signal, whereby the image quality and performance of the image display device 1 can be improved.
In order to exert the brightness and contrast characteristics of the liquid crystal panel as an image display element to the maximum extent, the image quality of the virtual image can be improved by setting the light incident to the liquid crystal panel within the above-described range.
The invention controls the diffusion characteristic and the directional characteristic of the light emitted by the liquid crystal panel:
In a typical television application device, the light emitted from the liquid crystal display panel, for example, as shown by the curves of "conventional characteristic (X direction)" in fig. 18 (a) and "conventional characteristic (Y direction)" in fig. 18 (B), has similar diffusion characteristics in the horizontal direction of the screen (the display direction corresponding to the X axis of the curve in fig. 18 (a)) and the vertical direction of the screen (the display direction corresponding to the Y axis of the curve in fig. 18 (B)).
In contrast, the diffusion characteristics of the light beam emitted from the liquid crystal display panel of the present embodiment are those shown by the curves of "example 1 (X direction)" in fig. 18 (a) and "example 1 (Y direction)" in fig. 18 (B).
In a specific example, the angle of view at 50% of the luminance (luminance reduced by about half) relative to the luminance of the front view (angle 0 degree) is set to 13 degrees, which is about 1/5 compared to the scattering characteristics (angle 62 degrees) of a general home television application device. Also, in the example in which the vertical upper and lower view angles are unevenly provided, the upper view angle can be suppressed to about 1/3 of the lower view angle (reduced) by optimizing the reflection angle, reflection area, and the like of the reflection type light guide.
By performing the above-described viewing angle setting or the like, the amount of image light in the user viewing direction (the user's viewing direction) is greatly increased (greatly improved in image brightness) as compared with the conventional liquid crystal television, and the related image brightness is 50 times or more.
Further, in the case of the viewing angle characteristic shown in "example 2" of fig. 18, when the viewing angle of 50% of the brightness (the brightness is reduced by about half) of the front view (angle 0 degree) brightness is set to 5 degrees, the viewing angle is about 1/12 (narrow viewing angle) of the diffusion characteristic (angle 62 degrees) of the general household television application device. Also, in the example in which the upper and lower view angles in the vertical direction are equally set, the relevant vertical view angle can be controlled (narrowed) to about 1/12 of that in the conventional manner by optimizing the reflection angle, reflection area, and the like of the reflection type light guide.
By doing this, the brightness (light quantity) of the image in the viewing direction (the direction of the user's line of sight) is significantly improved, and the brightness of the related image is 100 times or more, as compared with the conventional liquid crystal television.
The invention is suitable for the design of the optical component of the image light with a narrow divergence angle:
As described above, the light beam can be concentrated on the optical component by making the angle of view narrow, and therefore, with the optical component of the image source described above, not only the utilization efficiency of the image light can be significantly improved, but also the image light beam diverged from each image source can have a narrow divergence angle and a high density of light energy. Therefore, even with a small-caliber optical component, a real image or a virtual image with enough brightness can be obtained, aberration generated by the small-caliber optical component is reduced, and the correction difficulty is reduced, so that a bright and high-resolution enlarged image is realized. As a result, an image display device of a magnified image with low power consumption, high definition, and high brightness can be realized with a small number of lenses and concave mirrors.
When a large-sized liquid crystal display panel is used as an image source, the light around the screen when the center of the screen faces the viewer should be directed inward toward the optical element to enhance the overall brightness of the screen. On the other hand, when the panel size (screen ratio 16:10) of the image display device is 3 inches or less, the screen of the liquid crystal panel according to the present embodiment may be used vertically (hereinafter also referred to as "vertical use"), and the angle of the directivity characteristic in the horizontal direction may be greatly narrowed, thereby realizing an image display device with high luminance or low power consumption.
Further, with the light source device described above, the angle of the directional characteristic in the X-axis direction and the Y-axis direction can be greatly narrowed as compared with the diffusion characteristic of the emitted light of the conventional liquid crystal display panel (referred to as "conventional characteristic" in the drawings) illustrated in fig. 18 (a) and (B). In the present embodiment, by having such a pointing characteristic of a narrow angle, an image display device that emits an approximately parallel image beam in a specific direction and emits light of a specific polarization having a narrow divergence angle can be realized.
A second information display device of the information display system for a vehicle according to the present invention:
As described above, fig. 3 is an embodiment of the second information display system for a vehicle having a narrow-divergence-angle high-efficiency light source device, and the specific polarized image light beam obtained by the small and lightweight narrow-divergence-angle high-luminance image display device 4 is reflected by the windshield 6 so that the driver can see the virtual image. The information display device of the second embodiment has the light source device, which has high light conversion efficiency and low power consumption, can be driven by a mobile battery, can be carried around, can be placed on the instrument panel 42 when needed, and can be positioned at an optimal viewing position most suitable for a driver by adjusting the orientation and the height relative to the front windshield 6.
After passing through the front windshield 6, the sunlight entering the vehicle is reflected with S polarized light, and almost all of the sunlight is P polarized light. The polarizer provided on the incident surface of the liquid crystal panel is usually an absorption type polarizer, and absorbs P polarization. Therefore, the reliability of parts including a liquid crystal panel and the like can be greatly improved by providing an optical film or glass capable of reflecting P-polarized light on the windshield side of the absorptive polarizer.
In the case of using the liquid crystal panel described in this embodiment as an image light emitting device of a specific polarization, when polarized sunglasses are used, the brightness is significantly reduced due to large surface reflection of the sunglasses. To solve this problem, the image light can be changed into a mixed light of P-polarization and S-polarization by attaching a polarization cancellation element to the exit surface of the liquid crystal panel. In this way, even if the driver wears polarized sunglasses, a virtual image of sufficient brightness can be obtained.
Various implementations or embodiments (i.e., specific examples) to which the present invention is applied are described in detail above. On the other hand, the present invention is not limited to the above-described embodiment (specific example), but includes various modified examples. For example, the above embodiments describe the entire system in detail for the purpose of more clearly describing the present invention, and are not limited to the configuration in which all the structures described are necessarily provided. Furthermore, a part of the structure of a certain embodiment may be replaced with the structure of another embodiment, and the structure of another embodiment may be added, deleted, or replaced in the structure of a certain embodiment.
The light source device is not limited to application to an optical system having an image source with a narrow divergence angle characteristic and a virtual image mode image display device having the optical system, but is also applicable to display devices such as HUDs, tablet computers, digital signage, and the like.
As described above, the technology relating to the present embodiment can be applied to a vehicle-mounted image display device that can realize safe driving assistance, and further, the image display device is provided with a large-sized liquid crystal panel, and a virtual image display device that can realize high energy efficiency and high luminance and that becomes a transparent liquid crystal panel in a non-display state can be provided. The present invention, which provides this technology, can contribute to the "3. Provide health and well-being" in the sustainable development objective (SDGs: sustainable Development Goals) set forth in the united nations.
Further, according to the technology relating to the above embodiment, the divergence angle of the outgoing image light is reduced to be aligned with a specific polarization, and the light having only a specific polarization component and having a narrow diffusion angle (high linearity) can efficiently reach the eyes of the viewer outdoors or indoors. Therefore, a high light utilization efficiency, a bright and clear virtual image or an enlarged image of a real image can be obtained. The technique according to this embodiment can greatly reduce power consumption, and provides an optical system having excellent practicality and an image source with a narrow angle diffusion characteristic. The invention providing this technology can contribute to the "9. Construction of powerful industry, promotion of technical innovation" in the sustainable development objective (SDGs: sustainable Development Goals) proposed by the united nations.
Claims (12)
1. An image display device of virtual image mode, characterized in that:
the virtual image display device includes an optical system,
The optical system includes:
a display panel for displaying an image,
A light source device having a surface light emitting element for supplying light to the display panel,
The light source device includes, as a light source, a surface light emitting element arranged between the surface light emitting element and the display panel, and an optical element for reducing a divergence angle of a divergent light beam from a surface light source;
the divergent light beam is controlled in the direction of propagation inside the optical element by the shape of the light incident surface of the optical element, and the diffusion angle and the emission position of the light beam to the display panel can be controlled by designing the lens shape on the light emitting surface of the optical element.
2. A virtual image mode image display apparatus according to claim 1, wherein:
The optical element includes a reflection surface as a final surface, and the amount of light of the image light receiving optical element emitted from the image display surface of the display panel is determined by the light diffusion characteristic of the light source device.
3. A virtual image mode image display apparatus according to claim 2, wherein:
The aforementioned optical system includes a reflection surface as a final surface, displays an image displayed on the display panel as a virtual image,
The diffusion characteristic and the emission direction of the image light emitted from the image display surface, and the amount of received light by the optical element can be controlled by the diffusion characteristic of the light source device.
4. A virtual image mode image display apparatus according to claim 1, wherein:
the light source device includes a surface light emitting element as a light source, and an optical element capable of reducing a diffusion angle of a divergent light beam from a surface light source is arranged between the surface light emitting element and a display panel;
The light incident surface shape of the optical element can control the propagation direction of the diffused light beam in the optical element; the spread angle and the incidence position of the light beam emitted onto the display panel are controlled according to the designed lens shape on the light emitting surface of the optical element.
5. A virtual image display apparatus according to claim 4, wherein:
the light source device includes a surface light emitting element as a light source, and the optical element capable of reducing a spread angle of a divergent light beam from a surface light source is disposed between the surface light emitting element and the display panel;
the direction in which the diffused light beam propagates inside the optical element can be controlled by the shape of the entrance surface of the optical element; the optical element is made of plastic material or glass material, and controls the diffusion angle and incidence position of the light beam emitted onto the display panel according to the lens shape on the emitting surface.
6. A virtual image mode image display apparatus according to claim 1, wherein: the light source device has a surface light emitting element as a light source,
An optical element disposed between the surface light emitting element and the display panel for reducing a spread angle of a divergent light beam from a surface light source, wherein a direction in which the divergent light beam propagates inside the optical element is controlled by an incident surface shape of the optical element, and a spread angle and an incident position of the light beam emitted to the display panel are controlled by a lens shape and an decentered shape of a lens designed on a light emitting surface of the optical element.
7. An image display device for diffusing an image beam at a narrow diffusion angle,
An image display device of a virtual image mode, which reflects an image beam from the image display device by a reflecting surface separate from the image display device to obtain a virtual image, characterized in that:
The image display device includes
Display panel for displaying image
A light source device for providing light to the display panel,
The light source device has a surface light emitting element as a light source, and an optical element capable of reducing a divergence angle of a divergent light beam from a surface light source is provided between the surface light emitting element and a display panel,
An optical system which is formed as a final surface with a reflection surface of the image display device which is not in the same housing and which reflects the image light from the display panel so as to generate a virtual image to an image viewer;
The obtained image light forms a virtual image
The optical system receives image light from the image display surface of the display panel, is controlled by the diffusion angle of the image light from the display panel of the light source device,
The image beam obtained at the screen center of the aforementioned enlarged virtual image is blocked by the pupil of the virtual image viewer forming the aforementioned optical system.
8. An image display apparatus for diffusing an image light beam at a narrow diffusion angle as set forth in claim 7, wherein:
The optical element is an oblique projection optical element having an elevation angle of the final reflection surface with respect to the display panel,
The oblique projection optical component is an optical component capable of obtaining a virtual image which is slightly equal to the image displayed by the display panel,
The image display device is provided with a light source device capable of adjusting the incidence position and incidence angle of the image light emitted from the image display device and entering the final surface of the optical assembly.
9. An image display apparatus for diffusing an image light beam at a narrow diffusion angle as set forth in claim 7, wherein:
An optical sheet for mixing polarization directions of image light of specific polarization is attached to the image light emitting surface of the display panel.
10. An image display apparatus for diffusing an image light beam at a narrow diffusion angle as set forth in claim 7, wherein:
The optical assembly comprises a concave mirror and an optical element for controlling the angle of the image light emitted from the display panel entering the optical assembly, and is an optical assembly for obtaining a virtual image from an image displayed on the image display surface of the display panel;
the amount of image light received by the optical module from the display panel is determined by the diffusion characteristic of the image light from the display panel obtained by the light diffusion characteristic of the light source device.
11. An image display device of virtual image mode, characterized in that:
the image display device of the virtual image system includes an optical system,
The optical system includes:
A display panel for displaying an image and,
The light source device for supplying light to the display panel and,
The aforementioned optical assembly for receiving image light emitted from a display panel and method of manufacturing the same
An optical element having the light incident surface of the display panel;
The diffusion characteristics of the image light emitted from the display panel are different in the long side direction and the short side direction of the display panel;
The optical element has an effect of adjusting the direction of the image light emitted from the display panel to the optical module, and is a virtual image mode image display device capable of adjusting the incidence position and incidence angle of the image light emitted from the optical element to the optical module.
12. A virtual image mode image display apparatus according to claim 11, wherein:
The diffusion characteristic of the image light emitted by the display panel is adjusted by the diffusion characteristic of the light beam emitted by the light source device to the display panel, and is different in the direction of the long side and the short side of the image of the display panel;
the divergence angle of the image light in the long side direction of the picture emitted by the display panel is larger than that in the short side direction of the picture.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410225192.XA CN118011643A (en) | 2024-02-29 | 2024-02-29 | Image display device with virtual image mode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410225192.XA CN118011643A (en) | 2024-02-29 | 2024-02-29 | Image display device with virtual image mode |
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| Publication Number | Publication Date |
|---|---|
| CN118011643A true CN118011643A (en) | 2024-05-10 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410225192.XA Pending CN118011643A (en) | 2024-02-29 | 2024-02-29 | Image display device with virtual image mode |
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| Country | Link |
|---|---|
| CN (1) | CN118011643A (en) |
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- 2024-02-29 CN CN202410225192.XA patent/CN118011643A/en active Pending
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