JP2013068886A - Video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improvement device of an image display device using scans of laser beams, especially, a naked eye stereoscopic video display device with which stereoscopic video is projected onto a screen and multiple observers can observe the stereoscopic video with naked eyes.SOLUTION: The video display device includes: a laser beam generator 11 for emitting laser beams; a light deflector 12 for deflecting the emitted laser beams; a light scattering screen 14 for converting the light incident from the light deflector 12 into scattered light and radiating the same; a deflector controller for controlling the light deflector 12 and deflecting the laser beams incident on the light deflector so as to scan the whole area of a display surface of the light scattering screen 14; and a laser generator controller for controlling the laser beam generator 11 and sequentially generating the laser beams to be projected onto pixels on the light scattering screen according to video to be projected onto the light scattering screen 14.

Description

  The present invention relates to an image display device that displays an image on a screen by scanning with a laser beam modulated by an image signal, and more particularly to an autostereoscopic image projected onto a screen so that a plurality of observers can observe stereoscopic images with the naked eye. The present invention relates to a video display device.

In recent years, 3D video technology has been rapidly developed, and 3D video can be used in various aspects. For example, even in academic lectures and surgery review meetings, there are an increasing number of scenes where 3D images with high reproducibility to the actual object are used.
A 3D display device that allows an observer facing the screen to view a 3D image projected on a large screen allows multiple people to observe 3D images at the same time, such as amusement fields such as 3D movies, presentations at conferences, etc. Used for.

  For this reason, a display of a two-parallax stereoscopic display system is used in which an observer wears spectacles that separate the left eye field and the right eye field, and the left eye and the right eye display different images, respectively. The In addition, in order to eliminate the inconvenience of wearing glasses, a lenticular lens or a parallax barrier is used to control the direction of light and to display images with parallax to the left and right eyes, and a naked-eye stereoscopic body that does not require glasses Display devices have also been developed.

  These two-parallax stereoscopic display systems use the principle that humans can obtain a stereoscopic effect if different images are displayed on the right and left eyes. However, this method creates a contradiction between accommodation and convergence in stereoscopic viewing. While the brain perceives a solid at a different position from the display screen, the eye tries to focus on the screen. This contradiction causes eye strain during stereoscopic image observation. In addition, even if the observer changes the observation position, only an image viewed from the same direction is observed, which causes a sense of discomfort with respect to motion parallax and causes eye strain.

  As the parallax stereoscopic display method, there is a multi-view parallax stereoscopic display method in which the number of parallax images to be displayed is increased and the interval between viewpoints formed in a space is reduced. In the multi-view parallax stereoscopic display method, the observer can perform stereoscopic viewing based on binocular parallax, as in a conventional binocular display, by entering different images on the left and right at any position. Further, even if the observer moves left and right, a plurality of images are switched to the adjacent images while overlapping, so that a stereoscopic image that naturally changes according to the observation position can be observed.

Furthermore, when the viewpoint interval is reduced and two or more parallax images are simultaneously incident on the pupil, the image can be focused on the three-dimensional image by focusing on the same position on the retina, and adjustment and convergence can be reduced. The eye strain can be relieved consistently. A condition in which the viewpoint interval is narrower than the pupil diameter of the eye is called a super multi-view condition.
In this way, natural stereoscopic display without eye strain is enabled by a stereoscopic video display method that satisfies the super multi-view condition.

  Patent Document 1 discloses a stereoscopic image display device using a projection optical system fan-shaped array that realizes stereoscopic image display that can be observed with the naked eye while satisfying super multi-view conditions. FIG. 9 is a basic principle diagram for explaining the principle of the stereoscopic video display apparatus disclosed in this document. FIG. 9A shows an imaging system, and FIG. 9B shows a projection system.

  As shown in FIG. 9A, the disclosed stereoscopic video display apparatus photographs a subject at a predetermined interval by a plurality of video cameras arranged in a fan shape, and uses the captured parallax image as an original image in a projection system. . As shown in FIG. 9 (b), the stereoscopic image display device that is a projection system includes a plurality of projection unit optical systems arranged in a fan shape at the same angular intervals as a video camera, a concave mirror that functions as a screen, and an optical path change. With a half mirror for.

The projection unit optical system has a point light source, a condenser lens, a liquid crystal display panel, and a projection lens arranged in this order.
The liquid crystal display panel displays an image captured by a corresponding video camera as an original image. The light emitted from the point light source is collected by the condenser lens and illuminates the original image displayed on the liquid crystal display panel. The original image displayed on the liquid crystal display panel is projected and formed on the surface of the concave mirror by the projection lens, and the image formed on the concave mirror surface is condensed again by the concave mirror, reflected by the half mirror, and located in the viewing zone. An image is formed on the retina through the pupils of the left and right eyes of the observer.

An observer observes parallax images corresponding to the left eye and right eye, and perceives a stereoscopic image using binocular parallax and convergence. Furthermore, if the super multi-view condition where multiple parallax images are incident on both eyes is satisfied, the stereoscopic image position is focused, and a natural stereoscopic image with no contradiction in convergence and focus adjustment is observed with the naked eye without glasses. Can do.
However, the disclosed three-dimensional image display device using the projection optical system fan-shaped array requires, for example, 200 projection unit optical systems in the horizontal direction in order to secure a viewing area of 400 mm in the horizontal direction. In addition, it is necessary to provide a very large number of projection unit optical systems including the projector, and it is difficult for many observers to observe at the same time, and it is difficult to put it into practical use.

  Patent Document 2 discloses a high-density directional display type stereoscopic image display apparatus that realizes stereoscopic image display that can be observed with the naked eye while satisfying super multi-view conditions. FIG. 10 is a principle diagram showing a cross section of the projector for one column in the horizontal direction for explaining the basic principle of the stereoscopic video display device disclosed in this document, and FIG. 11 is used in the stereoscopic video display device of this document. FIG. 12 is a conceptual diagram showing the arrangement of a projection optical system array used in the stereoscopic image display apparatus of this document.

  The disclosed stereoscopic image display device displays a two-dimensional image group obtained by photographing an object at high density with a plurality of imaging devices having slightly different viewing angles on a projector arranged in high density in the horizontal direction. . In the disclosed apparatus, each two-dimensional image is enlarged as an enlarged image in the same region called a common image plane by a horizontally decentered imaging optical system provided for each projector via a projection optical system array that is also a parallax barrier. When projected, the shared lens causes a group of rays diverging from an enlarged image of the common image plane to be horizontal quasi-parallel rays having directivity for each enlarged image.

The projector includes a reflective liquid crystal display panel for each color of RGB that disassembles and displays the color image acquired by the imaging device, distributes light from the light source and irradiates each liquid crystal display panel, and generates a two-dimensional image of each color of RGB. Are integrated with a polarization beam splitter and supplied to the projection optical system as a color image.
The radiation optical system is formed by a projection lens and an aperture stop, and projects an integrated color image onto a common image plane of the screen. Light rays that diverge from the image projected on the common image plane are emitted backward as quasi-parallel rays by the shared lens of the screen.

  The direction of the quasi-parallel rays emitted from the image projected on the screen varies depending on the position of the image display surface with respect to the optical axis of the radiation optical system. 11A is a plan view showing a light beam state when the center of the image display surface is located on the optical axis of the radiation optical system, and FIG. 11B is a plan view of the center of the image display surface being the optical axis of the radiation optical system. On the other hand, it is a top view which shows a light ray state when located in the upper side in a figure.

In the disclosed embodiment, the central axis of the two-dimensional image display surface, the optical axis of the lens and the aperture, and the optical axis of the shared lens are decentered in parallel, and a light beam passing through the aperture stop center of the optical system passes through the center of the shared lens. It is configured to pass. Therefore, the display direction of the image necessary for the three-dimensional display is given from the beginning by the individual optical systems having eccentricity.
For example, on the image display surface located on the optical axis of the radiation optical system, the quasi-parallel light emitted from the image is directed parallel to the optical axis (FIG. 11A), but the image display surface is on the upper side of the optical axis. In the position, the quasi-parallel light beam is directed obliquely downward in the figure (FIG. 11 (b)).

  In order to increase the number of two-dimensional images to be displayed in an overlapping manner and simplify the configuration, it is possible to use a projection optical system array in which individual projection optical systems are arranged in a matrix. As shown in FIG. 12, the projection optical system array includes a two-dimensional image display device array in which integrated color video display surfaces in a projector are arranged in a matrix, and an arrangement of each color video display surface. A lens array in which projection lenses are arranged in a matrix at the rear and an aperture array in which openings are arranged behind the projection lens are arranged in this order.

  The projection optical system array shown in FIG. 12 is configured for a two-dimensional image display device that is 25 image generation sources. The two-dimensional image display device is arranged so that the horizontal positions do not overlap each other by being obliquely shifted from each other in both the horizontal direction and the vertical direction. Thereby, 25 different two-dimensional images can be projected onto the common image plane on the screen. The 25 two-dimensional images transmitted through the screen are projected onto the pupils of the observer by quasi-parallel rays having different directivity directions.

The observer can recognize the spatial position of the stereoscopic image by focusing the quasi-parallel light incident on the pupil as a directional light emitted from the object. If the directional light incident on the eye satisfies the super multi-view condition, a natural stereoscopic image consistent with convergence and focus adjustment can be observed without glasses.
However, the disclosed high-density directional display type stereoscopic image display device has a density that satisfies the super multi-view condition before the projection optical system array, like the stereoscopic image display device by the projection optical system fan array. Thus, it is necessary to arrange a very large number of projectors for displaying a two-dimensional image, and it is difficult to put it into practical use.

On the other hand, instead of projecting the image on the image display surface for displaying the two-dimensional image on the screen, a video signal is formed by integrating the two-dimensional images to be displayed in a multiplexed manner, and the color light beam modulated according to the video signal is displayed on the screen. It is possible to consider an optical scanning type stereoscopic image display apparatus that can be observed as a three-dimensional image by irradiating the light.
A laser generator using a semiconductor element can perform optical modulation in a sufficiently high frequency region. Further, it is possible to form an image by scanning a predetermined screen with a laser beam.

  Furthermore, if a lenticular lens or a parallax barrier is used to give each of the images displayed on the screen different directivities, a light beam from a plurality of images with different directivities is incident on the pupil. A stereoscopic image display device of a high-density directional display system that can be viewed can be configured.

However, direct viewing of the laser beam must be avoided from the viewpoint of eye safety.
In order to obtain a more natural three-dimensional image with no contradiction in convergence and focus adjustment, it is preferable that a larger number of directional two-dimensional images can be displayed in a multiplexed manner.

JP 2002-258215 A JP 2007-309975 A

  Therefore, the problem to be solved by the present invention is to provide an improved image display device that is safe for the eyes using scanning of laser light. It is an object of the present invention to provide an autostereoscopic image display device that can observe an image.

  An image display device according to the present invention includes a laser beam generator that emits a laser beam, a beam deflector that deflects the emitted laser beam, and light that is converted from the beam deflected from the beam deflector into scattered light and emitted. A scattering screen, a deflector controller that controls the beam deflector to deflect the laser beam incident on the beam deflector so as to scan the entire display surface of the light scattering screen, and a laser beam generator that controls the light And a laser generator controller for sequentially generating laser light to be projected onto the pixels of the light scattering screen corresponding to the image projected onto the scattering screen.

The image display apparatus of the present invention can display a two-dimensional image by scanning a light scattering screen with a laser beam directly modulated according to image information.
When a laser beam is scanned and an image is projected on the screen, a highly coherent laser beam enters the eyes of an observer who observes the screen from behind the screen, which is dangerous. However, according to the image display device of the present invention, since the laser beam traveling straight from the light deflector is converted into scattered light by the light scattering screen, the scattered light is incident on the eyes of the observer to ensure eye hygiene. .

The light scattering screen is preferably formed by mixing and diffusing transparent particles having different light refractive indexes in a transparent base material.
In particular, the base material of the light scattering screen is preferably an acrylic resin, and the particles mixed and diffused in the base material are preferably bubbles.
For example, a liquid resin is mixed while being vibrated and mixed in a state where a large amount of small bubbles (microbubbles) are formed, or a microballoon filled with air is mixed into an acrylic resin base material. A light scattering screen can be formed by the method. In addition, according to the method of taking in air bubbles using a microballoon, it is possible to form a light scattering screen in which the particle size and density of the air bubbles are managed relatively accurately.

  By forming the light scattering screen by diffusing transparent particles with different light refractive indexes in a transparent base material, coherency is maintained from the rear of the screen while maintaining the intensity and color of the light hitting the light scattering screen appropriately. Can emit lost light. Therefore, an observer behind the light scattering screen can observe the image projected on the screen with the naked eye.

  Moreover, it is preferable that the light scattering screen includes a light shielding wall that partitions cells corresponding to pixels. The light shielding wall can be formed by attaching a metal film to the surface of a transparent base material plate mixed with transparent particles and punching holes having a necessary pattern by photoetching in the metal film. The light shielding wall may be a thin metal plate having a honeycomb structure, and a light scattering screen may be formed by embedding a base material mixed with transparent particles in the opening.

When the light scattering screen is provided with a light-shielding wall that partitions the cells corresponding to the pixels, mixing with light rays incident on adjacent pixels can be prevented and a clear image can be obtained.
The light shielding wall can also be formed by applying a light shielding plate having an opening on the surface of the light scattering plate.

  Further, by providing a lens mechanism between the light deflector and the light scattering screen, the direction of the light incident from the light deflector is converted to be parallel to the optical axis and incident on the light scattering screen. Since light scattering occurs more efficiently along the axis, a clear image can be obtained even when the screen is thin.

  A laser generator using a semiconductor element can perform optical modulation in a sufficiently high frequency region. For this reason, the laser beam obtained by directly modulating the laser generator using a video signal obtained by integrating a plurality of two-dimensional images, instead of projecting the image on the video display surface for displaying the two-dimensional image on a screen by a projector or the like. By scanning the image, multiple images can be displayed on one screen.

If a plurality of continuous parallax images are presented, stereoscopic image observation by so-called binocular parallax becomes possible. Furthermore, if the viewpoint interval is reduced using a large number of parallax images, the line of sight can be converted more smoothly when the face is moved.
Furthermore, a lenticular sheet or a parallax barrier that forms a plurality of viewpoint positions is provided behind the light emitting surface of the light scattering screen, and a multi-view display image is projected onto the corresponding pixels, so that the naked eye without glasses can be used. A stereoscopic video display that can be observed can be obtained.

Furthermore, if the viewpoint interval is made smaller than the diameter of the human pupil to satisfy the super multi-view condition, two or more parallax images are simultaneously incident on the pupil and formed at the same position on the retina. Since focusing is performed on the position of the image, there is no contradiction between convergence and focus adjustment in the parallax between the left and right eyes, and super multi-view stereoscopic image observation with little eye strain is possible with the naked eye.
In order to satisfy the super multi-view condition, it is necessary to project a large number of images in multiple. The laser beam generator can generate a laser beam corresponding to a high-frequency image signal, and by applying horizontal scanning and vertical scanning by a beam deflector to this, a large number of images can be projected on a large screen. .

Using a laser light generator that generates a color laser beam mixed with RGB 3 waves, each cell of the light scattering screen is dyed by the color of the incident color laser beam and emits the same color beam from the back side of the screen. The image display device can display a color image.
Therefore, a plurality of pieces of image information are integrated and converted into one video signal, and a laser beam emitted from the laser generator is modulated by the video signal to generate an arbitrary color beam. By scanning the screen surface and displaying an image, a plurality of color images can be simultaneously displayed on the screen.

For example, the video signal generation device generates a video signal that is intensity-modulated for each RGB from the parallax image information supplied for each video camera, and the number of parallax images for which the generated video signal for each RGB is to be displayed. By arranging them in sequence, they are supplied to the laser generator controller and the deflector controller as an integrated video signal.
The laser generator controller and the deflector controller can superimpose and display a large number of color images by scanning the screen surface with mixed color laser light according to the supplied video signal.

Since the light scattering screen used in the video display device of the present invention can be formed very easily as compared with a liquid crystal display or the like, the color video display device according to the present invention has a great economic advantage.
It is to be noted that a laser light sensor is arranged outside the image display area of the display screen so that an alarm is issued when no laser light is detected even after a time exceeding the horizontal scanning period has elapsed, and an eye caused by leakage of the laser light. Can be made to avoid the dangers.

  The image display apparatus according to the present invention can display an image on a large screen economically with a simpler configuration by using a method in which a laser beam is directly scanned on a light scattering screen. In particular, in the stereoscopic image display apparatus for obtaining a stereoscopic image with the naked eye without glasses according to the present invention, a large number of images are projected in multiple to satisfy the super multi-view condition, It is possible to reduce the contradiction of convergence and observe stereoscopic images with little eye strain.

It is a block diagram which shows the principle of the video display apparatus based on one Example of this invention. It is a conceptual diagram which shows the structural example of the laser beam generator and light beam deflector in a present Example. It is explanatory drawing which shows the example of the light-scattering screen in a present Example. It is explanatory drawing which shows another example of the light-scattering screen in a present Example. It is drawing explaining the relationship between the light-scattering screen and a lenticular sheet in a present Example. It is drawing which shows the optical path of the light ray which permeate | transmits the light-scattering screen and cylindrical lens in a present Example about an optical axis light. It is a conceptual diagram explaining the system which multiplex-displays a color image about the example of the light-scattering screen in a present Example. It is a conceptual diagram explaining the operation | movement system of a present Example. It is a conceptual surface explaining a basic principle about the example of the stereoscopic image display apparatus of a projection optical system fan arrangement system. It is a conceptual diagram explaining the basic principle about the example of the stereoscopic video display apparatus of a high-density directional display system. It is a conceptual diagram explaining the structure of the projection optical system array used for the stereoscopic video display apparatus shown in FIG. It is a conceptual diagram explaining arrangement | positioning of the projection optical system array used for the three-dimensional video display apparatus shown in FIG.

  Hereinafter, based on an example, an image display device concerning the present invention is explained in detail, referring to drawings. In this embodiment, the present invention is applied to a 3D color image display apparatus without glasses (naked eye). In the drawings, constituent members having the same function are denoted by the same reference numerals to simplify the description and avoid duplication of description.

FIG. 1 is a block diagram showing the principle of a video display apparatus according to one embodiment of the present invention.
The image display device of this embodiment is formed by a laser light generator 11, a light beam deflector 12, and an image display screen 20. The video display screen 20 preferably includes the light scattering screen 14 in order to convert a laser beam into a beam having lost coherency, and is preferably provided with a lenticular sheet 15 for autostereoscopic video display. Further, a Fresnel lens 13 that covers the entire surface of the light scattering screen 14 may be added in order to display a better image.

  FIG. 2 is a conceptual diagram showing a configuration example of the laser beam generator 11 and the beam deflector 12 necessary for using a color laser beam having an appropriate hue and light intensity. The laser light generator 11 includes a red laser generator 22, a green laser generator 23, and a blue laser generator 24, and the laser beam output from each laser generator is transmitted through a reflecting mirror 25 and half mirrors 26 and 27. And is output as a single color laser beam 28.

A laser generator controller 21 is attached to the laser light generator 11. The laser generator controller 21 extracts intensity signals of RGB colors from a color video signal supplied from a signal supply device (not shown) to control the laser generators 22, 23, and 24 for each color and display an image to be displayed. A color laser beam that changes along the scanning line is output corresponding to the color displayed on the pixel.
In addition, as a method of mixing RGB three-color laser beams, a method using a light guide tube that mixes colors by inputting RGB into an optical fiber, a method of directly using a light emitting diode chip on which three-color LEDs are mounted, and the like are used as appropriate. Various known methods can be applied.

  The beam deflector 12 has a well-known configuration such as a pair of reflecting mirrors that swing in the horizontal and vertical directions, a pair of polygon mirrors that rotate in both directions, or a reflecting mirror that swings in both directions. Have The beam deflector 12 is accompanied by a deflector controller 29. The deflector controller 29 can sequentially scan the pixels arranged on the entire surface of the image display screen 20 by deflecting the emission direction of the color laser beam 28 incident on the light deflector 12 in the horizontal direction and the vertical direction. .

  A person observes an image from the back side of the image display screen 20. When a laser beam is directly inserted into the eyeball 16 when observing an image, a problem arises in the hygiene of the eyes. Therefore, the laser beam converted into safe light is observed by the light scattering screen 14 constituting the video display screen 20. To do. The light scattering screen 14 scatters a laser beam, which is a linearly coherent light, with a fine structure and emits it as a light beam that has lost its coherency.

  FIG. 3 is a cross-sectional view illustrating an example of a light scattering screen used in this embodiment. The light scattering screen 14 shown in FIG. 3 is a plate material composed of the light scattering material 31. The light scattering material 31 is formed by mixing and distributing a large amount of fine transparent particles 33 having a refractive index different from that of a base material in a transparent base material 32.

When the laser beam 34 having high coherence and directivity is incident on the light scattering screen 14, the laser beam 34 violently reflects while passing through the light scattering material 31, so that the light emitted from the back surface of the light scattering screen 14 is It becomes the scattered light 35 which lost coherent property. Further, the polarization plane of the laser beam 34 is also disturbed during transmission, and becomes a scattered light 35 in which the polarization is eliminated.
Even if the optical paths of the RGB laser beams 34 are not integrated but separated for each color, the RGB colors are mixed while passing through the light scattering material 31 if they enter the same region of the light scattering screen 14. Then, it is emitted as safe scattered light 35 having a composite color.

It is preferable to use a highly transparent material such as acrylic resin for the base material 32 of the light scattering screen 14. The transparent particles 33 may be bubbles.
In the light scattering screen 14 formed using an acrylic resin as a base material, since the material is highly transparent, attenuation of light intensity is small and strong transmitted light can be obtained. Further, since the refractive index of the transparent base material 32 is 1.49, whereas the refractive index of the transparent particles 33 that are bubbles is 1.0003, which is significantly different from the refractive index, the incident laser beam 34 is reflected by the light scattering screen 14. While transmitting the light, it collides with a large number of transparent particles 33 and repeats reflection and refraction to greatly change the direction of the light beam to reduce the directivity, and it is emitted as scattered light 35 diffusing at a wide angle.

In order to entrap air bubbles in the acrylic resin, there is a method in which a microballoon containing air is mixed to cure the resin. According to this method, uniform bubbles can be formed in the transparent resin with an appropriate density relatively easily.
For example, in an acrylic resin in which bubbles having a diameter of 1 μm are generated at a density of 50% with respect to the close-packed state, the rate at which the first laser beam is transmitted with a thickness of about 1.5 mm is about 0.01%. A sufficiently coherent laser beam can be transformed into safe scattered light. If the density of the bubbles is about 30% of the closest packing, the transmittance is about 0.01% at a thickness of about 2.2 mm, which is almost safe.

FIG. 4 is an explanatory view showing another example of the light scattering screen 14.
The laser beam 34 incident on the light scattering screen 14 is repeatedly refracted while passing through the light scattering material 31 and is emitted as safe scattered light 35, but depending on the thickness of the light scattering material 31, May mix with light. The various light scattering screens 14 shown in FIG. 4 can observe clear images by providing a light shielding area between the openings to prevent interference between pixels.

FIG. 4A shows a light scattering screen 14 formed by attaching a mask 36 having an opening 30 to a portion corresponding to a pixel on the surface of a plate formed of the light scattering material 31 described in FIG. The mask 36 is formed by forming a metal film that shields light on the surface of the plate formed of the light scattering material 31, and then providing an opening 30 in a portion corresponding to the pixel of the metal film by photoetching, similar to the shadow mask, A fine pattern can be formed precisely.
The diameter of the opening 30 is preferably formed smaller than the diameter of the laser beam 34.

  FIG. 4B shows a light scattering screen 14 formed by filling a light scattering material 31 into an opening portion of a shielding plate 37 having an opening 30 precisely bored as in the mask shown in FIG. is there. The laser beam 34 incident on the portion of the opening 30 is not mixed with the laser beam irradiated to the adjacent opening 30 and loses the coherent property by eliminating the polarization and straightness while passing through the light scattering material 31. It changes into scattered light 35 that is safe for the eyes.

  FIG. 4C shows the light scattering screen 14 formed by filling the light scattering material 31 into the opening 30 of the honeycomb window partitioned by the walls of the honeycomb plate 38. Each honeycomb window of the honeycomb plate 38 corresponds to a pixel of one image of the light scattering screen 14, and the laser beam 34 incident on the honeycomb window loses coherency while passing through the light scattering material 31 and becomes scattered light 35. Eject.

  In the light scattering screen 14 having a partition wall, when the incident angle of the laser beam incident on the opening 30 is large, the light is unevenly distributed in a portion close to the wall opposite to the incident direction, and the intensity distribution is uneven in the exit opening. Tend to become. In order to prevent this and make a uniform luminous intensity distribution over the entire opening 30, there is a method of increasing the thickness of the light scattering material 31, but when the light scattering material 31 becomes thicker, the intensity of transmitted light is attenuated. there's a possibility that.

In order to suppress the uneven distribution of the intensity of the scattered light 35 while suppressing the thickness of the light scattering material 31, the incident angle of the laser light incident on the light scattering material 31 is reduced to be incident on the central portion of the opening 30. It is preferable.
In this embodiment, as shown in FIG. 1, a Fresnel lens 13 is arranged in front of the light scattering screen 14.

  The Fresnel lens 13 is a convex Fresnel lens formed approximately the same size as the light scattering screen 14, and is arranged so that the focal point is at the position of the light deflector 12. The laser beam deflected by the beam deflector 12 changes the incident angle to the Fresnel lens 13 according to scanning. The Fresnel lens 13 deflects the direction of the laser beam parallel to the optical axis regardless of the incident angle, and makes it incident on the surface of the light scattering screen 14 substantially perpendicularly. The laser beam perpendicularly incident on substantially the center of the pixel filled with the light scattering material 31 becomes scattered light 35 having a more uniform intensity distribution over the entire exit surface of the opening 30.

  FIG. 5 is a diagram for explaining the relationship between the light scattering screen 14 and the lenticular sheet 15 in an image display device in which a plurality of images are projected in an overlapping manner. The lenticular sheet 15 is formed by vertically arranging semi-cylindrical cylindrical lenses 41, and the width of one cylindrical lens 41 corresponds to one pixel of an image to be displayed. That is, when several images are projected in an overlapping manner, the width of one cylindrical lens 41 is formed so that all the bright spots corresponding to the same pixel in the image projected in an overlapping manner are included. The bright spots corresponding to one pixel may be arranged in a matrix composed of a plurality of horizontal stages.

The light scattering screen 14 is formed with an opening 30 filled with a light scattering material 31 that is irradiated with a laser beam and emits scattered light.
FIG. 5 displays a light scattering screen aperture array 39 corresponding to one cylindrical lens 41. In the configuration example shown in FIG. 5, as the pixels corresponding to the same position of 36 images, the rectangular openings 30 arranged in two rows at the top and bottom in the width of the cylindrical lens 41 are slightly displaced in the horizontal direction and are 36 pixels. Needless to say, other appropriate numbers may be used.
The laser beam is scanned while sequentially irradiating the openings filled with the light scattering material 31 arranged at the same height in the horizontal direction.

  FIG. 6 is a horizontal sectional view conceptually showing the optical path of the light beam that passes through the light scattering screen 14 and the cylindrical lens 41. As shown in FIG. 6, the light beam of the scattered light 35 emitted from the opening 30 filled with the light scattering material of the light scattering screen 14 is emitted by the cylindrical lens 41 in different fixed directions according to the position of the opening. The pixels of one image correspond to the openings 30 having the same arrangement relationship with respect to the cylindrical lens 41, and light rays related to one image are emitted in the same direction over the entire image. Therefore, one video image is observed as a set of pixels projected in the same direction from the entire surface of the light diffusion screen 14.

For example, a laser beam 34 represented by a light beam A corresponding to a pixel in the image is emitted after being scattered light 35 in the opening of the light scattering screen 14, refracted by the cylindrical lens 41, and directional light 18 in a predetermined direction. Is emitted as. Rays A from the same image are emitted from the corresponding apertures 30 in the same direction a, and this image can be observed from the direction a. On the other hand, the laser beam represented by B is emitted in the direction b from the corresponding opening 30 of the cylindrical lens 41, and the image can be observed from the direction b.
Thus, a plurality of images having different directivity directions can be displayed on the video display screen 20. With the light scattering screen 14 and the lenticular sheet 15 having the arrangement as shown in FIG. 5, 36 images can be simultaneously projected.

FIG. 7 is a view for explaining a method of displaying multiple color images using the video display screen 42. FIG. 7A is a conceptual diagram illustrating a configuration of a video display screen, and FIG. 7B is a conceptual diagram illustrating a video signal for generating a laser beam to be scanned.
In FIG. 7A, the video display screen 42 includes a Fresnel lens 13, a light scattering screen 14, and a lenticular sheet 15. The Fresnel lens 13 has a function of causing a laser beam to enter the surface of the light scattering screen 14 substantially perpendicularly.

The color laser beam generated by the laser beam generator 11 repeats the horizontal scanning 45 according to the vertical scanning 46 by the beam deflector 12 shown in FIGS. Scan. For example, for high-definition television level display, for example, a video display screen having 1920 pixels in the horizontal pixel row and 1080 pixels in the vertical pixel row is used.
A laser light detection sensor 44 is arranged at the right end of the video display area 43 of the video display screen 42.

When the color laser beam irradiates the aperture corresponding to the pixel of the light scattering screen 14, a beam having the same color as the color laser beam is emitted from the position of the aperture of the lenticular sheet 15 with respect to the cylindrical lens.
By disassembling one image so as to correspond to the pixels of the light scattering screen 14 and scanning while projecting color light rays corresponding to the pixels for each aperture at the same position with respect to the cylindrical lens corresponding to the pixels, The entire image can be displayed on the display screen 42. If another image is scanned so that light is projected to each opening at another predetermined position corresponding to the pixel with respect to the cylindrical lens, another entire image can be displayed in the same manner.

In the configuration shown in FIG. 5, since 36 openings are provided in the area corresponding to the pixels of the cylindrical lens, a maximum of 36 different images can be displayed on the video display screen 42. The numerical aperture in one pixel can be further increased according to the size of the screen, the size and shape of the aperture, the configuration of the aperture matrix, and the like. It should be noted that if the number of parallax images (number of parallaxes) is 50 to 100, it can be observed as a completely natural stereoscopic image. It is not difficult to provide a parallax number of 90 to 120 with a large screen of 300 to 400 inches installed in a theater.
In this way, for each video image to be multiplexed and displayed, a large number of images with different directivities are generated by projecting the light to be displayed on the pixel at the same position with respect to the cylindrical lens covering the pixel. Can be made.

FIG. 7B shows a video signal conceptually represented with respect to the horizontal scanning 45. The video signal in this embodiment conforms to the video signal, and includes a laser light detection sensor signal 55 in addition to the horizontal synchronization signal 51, the color burst signal 52, and the video signal 53 instructing the start of the horizontal scanning 45. . For example, in the case of conforming to a 1920 × 1080 interlaced high-definition television, the horizontal scanning time is approximately 30 μs. Further, when openings corresponding to pixels are arranged in a multi-stage matrix, the number of horizontal scans is multiplied by the number of stages, and the scanning time corresponding to one stage of horizontal scan is shortened according to the number of stages.
Note that a plurality of color projectors may be provided, and a plurality of laser beams may be scanned at the same time, and scanning may be performed for each stage of the aperture matrix. If a plurality of projectors are used, the horizontal scanning time can be increased and signal processing is simplified.

  The video signal 53 is a waveform in which signals representing hue and brightness in pixels of a video to be displayed are arranged in order corresponding to the openings arranged on the horizontal scanning line. A plurality of apertures (18 in FIG. 5) for displaying different images with respect to one cylindrical lens 41 are provided on the trajectory through which the horizontal scanning line passes. One image is formed by combining the pixels in the aperture at the same position with respect to the cylindrical lens. Therefore, the video signal 54 for displaying the image has a plurality of images (parallax image, The number (36 in FIG. 5) arranged on the same horizontal scanning line (36 in FIG. 5) is incorporated in the horizontal scanning video signal 53 so as to appear periodically. In addition, it is preferable to arrange a dummy opening at a portion where the cylindrical lenses are joined next to each other so as to correspond to a zero or dummy video signal so that light is not irradiated.

The video signal 53 is decomposed into RGB, converted into intensity signals for each color, and distributed to the red laser generator 22, the green laser generator, and the blue laser generator 24 via the laser generator controller 21, respectively. According to this signal, laser beams of RGB colors having a desired hue and brightness are generated.
Further, the deflector controller 29 controls the light deflector 12 based on the horizontal synchronizing signal and the vertical synchronizing signal incorporated in the video signal so that the horizontal scanning 45 and the vertical scanning 46 of the video display screen 42 are performed with the laser beam. .

  Since the video signal 53 needs to give a modulation signal of a color laser beam to be irradiated to all the apertures on the horizontal scanning line, for example, in the example of 36 parallax images shown in FIG. 5, a cylindrical lens corresponding to one pixel. In this area, 36 openings are arranged in two rows. Therefore, it is necessary to include 18 apertures × 1920 pixels = 34,560 color signals within 15 μs of one horizontal scan. If the number of images to be multiplexed is increased, it is necessary to use a higher frequency image signal. However, the direct modulation speed of the semiconductor laser is still about 40 GHz, and the response speed of the laser generator is extremely fast. Can be displayed in multiple.

Since the laser beam has a small diameter and does not diffuse, it is easy to prevent mixed display by preventing light from protruding into the adjacent aperture when entering the laser beam into one aperture. Even when the GRB laser beams are separated, if all the RGB laser beams are incident on one opening, light having the hue and brightness after the RGB combination of RGB is emitted. In addition, the light beam from the adjacent aperture is not affected.
In particular, those provided with light-shielding walls that partition the cells for each opening can prevent the interference with adjacent cells and can arrange the openings with high density.

Since it is dangerous if the laser beam directly enters the eye, it is preferable to always monitor the abnormality of the laser beam to be scanned and stop the laser beam when the abnormality occurs. For this reason, a laser beam detection sensor 44 is arranged at one end in the horizontal direction of the video display screen 42, and the laser beam is detected by the laser beam detection sensor 44 for each horizontal scan, thereby confirming the normal state. The laser light detection sensor signal 55 included in the video signal is a video signal that generates a laser beam that is detected by irradiating the laser light detection sensor 44.
If the laser beam detection sensor 44 does not detect the laser beam even if the time longer than the horizontal scanning time elapses during the scanning of the laser beam, an abnormality may occur, and the laser generator is stopped for safety. be able to.

FIG. 8 is a conceptual diagram illustrating the principle of observing a stereoscopic image without glasses with the image display device of the present embodiment.
A two-dimensional image composed of color laser beams emitted from the beam deflector 12 is formed on the video display screen 42. Two-dimensional images can be displayed by the number of openings formed in the area of the cylindrical lens corresponding to one pixel. From the two-dimensional image displayed on the video display screen 42, light beams directed to a predetermined angle in the horizontal direction are diffused with high density for each image, and the viewer sees the video display screen 42 from the rear. Several images are observed from the rays.

  When an observer sees a certain feature point coexisting in several images, if the feature point position is different in different images, each feature point can be obtained by focusing on the feature points 57 and 58 appearing on the screen. The image is formed at a position distant from the retina. However, when a plurality of light rays representing the same feature point are input from a plurality of images into one pupil, and so-called super multi-view conditions are satisfied, these images are focused on one point on the retina. Adjustment can be made and the focus is adjusted to the position of the object point 59. If focus adjustment can be performed at the same object point 59 for both the left and right eyes, stereoscopic image observation with no contradiction between the convergence position of the left and right line of sight and the focus adjustment becomes possible.

  The size of the video display screen 20 for displaying an image can be appropriately selected from a small screen installed on a table to a large screen such as a cinema in a theater. However, there are restrictions due to the diameter of the laser beam, the size of the opening through which the laser beam enters, the direct intensity modulation speed of the laser beam, and the like. The definition of the image is determined by the number of lenticular lenses included in the screen in the horizontal direction. On the other hand, the number of screens to be multiplexed, that is, the number of parallaxes is determined by the number of openings arranged on the back surface of the lenticular lens corresponding to one pixel.

  The larger the screen of the video display screen 20, the greater the number of parallaxes. On a 300-400 inch screen corresponding to a cinema, 90-120 parallax can be easily realized. In the multi-view stereoscopic display method, if the number of images to be multiplexed and displayed in the horizontal direction can be reduced to about 50 to 100, a natural stereoscopic image can be displayed, and a stereoscopic image from a free viewpoint can be enjoyed. Note that shooting using 100 cameras is not realistic, so a method of generating a necessary number of videos by interpolation from an appropriate number of videos obtained by shooting with the number of cameras capable of shooting is used. be able to.

When a large image display screen 20 is installed and scanned with a color laser beam to form a large number of parallax images, and an observer on the back side observes an image, the observation position differs depending on the observer. Regardless, each observer can observe a stereoscopic image by allowing a plurality of parallax images to enter the pupil of the naked eye.
As described above, the video display apparatus according to the present embodiment is a simple apparatus using one or a plurality of color laser scanning apparatuses and is an autostereoscopic video display apparatus that performs a high-density directional display method. When a plurality of screens obtained by dividing a large screen are integrated to display one stereoscopic image, a color laser scanning device may be provided for each screen.

  The image display apparatus of this embodiment displays a large number of directional color images on the image display screen by scanning the screen with a color laser beam having a display color to change the light scattering material at the pixel position to the display color. It is. Therefore, a large number of parallax images displayed on a color liquid crystal display surface are mounted on a directional light beam and observed as a three-dimensional image using a large number of image display devices each having a color liquid crystal display surface composed of pixels that generate RGB colors. The configuration and the operating principle are greatly different from conventional methods such as an integral imaging autostereoscopic display device.

In particular, in conventional super multi-view stereoscopic video display devices and high-density directional stereoscopic video display devices, it is necessary to arrange as many video display devices as the number of images to be multiplexed behind the screen, and the large size has a complicated structure. However, since the image display apparatus of this embodiment projects a large number of images at the same time using a laser generator that can easily operate at high speed with a high-frequency signal, the configuration is simplified and the apparatus is downsized.
Note that the video display apparatus according to the present embodiment can independently display as many images as the number of openings filled with a light scattering material provided in a region corresponding to a pixel of the video display screen.

  The technical idea of the present invention can be applied to a parallax barrier type or lenticular type autostereoscopic display device, thereby realizing a more natural three-dimensional display compared to a conventional device. Needless to say, the technical idea of the present invention can also be applied to a conventional flat image display device for observing a two-dimensional image or a video display device for displaying a monochromatic image using a monochromatic laser beam.

  The present invention provides a video display device having a simpler configuration, and further provides a stereoscopic video display device that can be observed with the naked eye with a simpler configuration.

DESCRIPTION OF SYMBOLS 11 Laser beam generator 12 Beam deflector 13 Fresnel lens 14 Light scattering screen 15 Lenticular sheet 16 Eyeball 17 Laser beam 18 Directional beam 19 Laser scanning 20 Image display screen 21 Laser generator controller 22 Red laser generator 23 Green laser generation Unit 24 Blue laser generator 25 Reflector 26 Half mirror 27 Half mirror 28 Color laser beam 29 Deflector controller 30 Aperture 31 Light scattering material 32 Transparent base material 33 Transparent particle 34 Laser beam 35 Scattered light 36 Mask 37 Perforated substrate 38 Honeycomb plate 39 Light scattering screen aperture array 41 Cylindrical lens 42 Video display screen 43 Video display area 44 Laser light detection sensor 45 Horizontal scan 46 Vertical scan 51 Horizontal sync signal 52 Color burst signal 53 Video signal 54 Display of image of interest Signal 55 Laser light detection sensor signal 56 Pupil 57, 58 Image on screen 59 Object position 63 Light scattering screen aperture 64 Lens 65 Aperture array aperture 66 Horizontal scan 67 Vertical scan 68 Parallax barrier 70-1 to n Video camera 71 Subject 72 Displayed images 80-1 to 80-n Projection unit optical system 81 Light source 82 Condenser lens 83 LCD
84 projection lens 85 concave mirror 86 half mirror 87 eyeball 88 pupil 91 two-dimensional image display device array 92 two-dimensional image display device 93 lens array 94 lens 95 aperture array 96 aperture 97 three-dimensional screen

Claims (9)

  Laser beam generator for emitting laser beam, beam deflector for deflecting laser beam emitted from the laser beam generator, and light scattering screen for converting the beam incident from the beam deflector into scattered light and emitting it A deflector controller that controls the beam deflector to deflect the laser beam incident on the beam deflector so as to scan the entire display surface of the light scattering screen; and the laser beam generator. And a laser generator controller for sequentially generating laser light to be projected onto the pixels of the light scattering screen corresponding to the image projected onto the light scattering screen.   The image display device according to claim 1, wherein the light scattering screen is formed by including a light scattering material in which transparent particles having different light refractive indexes are diffused in a transparent base material.   The video display device according to claim 2, wherein the light scattering screen includes a light shielding wall that partitions cells corresponding to pixels.   The video display device according to claim 2, wherein a base material of the light scattering screen is an acrylic resin, and particles diffused in the base material are bubbles.   5. The image display device according to claim 1, wherein the laser light generator generates a color laser beam in which RGB three waves are mixed. 6.   Further, a lens mechanism is provided between the light deflector and the light scattering screen so as to make the direction of the laser beam incident from the light deflector parallel to the optical axis and enter the light scattering screen. 6. The video display device according to any one of items 1 to 5.   Furthermore, a lenticular sheet or a parallax barrier for forming a plurality of viewpoint positions is provided behind the light emitting surface of the light scattering screen so as to display a multi-view stereoscopic image. 2. The video display device according to item 1.   Furthermore, the video display apparatus according to claim 7, wherein a super multi-view condition is satisfied by making an adjacent distance of the viewpoint position smaller than a diameter of a human pupil.   9. The sensor according to claim 1, further comprising a sensor that is arranged outside a video display area of the display screen and issues an alarm when a laser beam is not detected even after a time exceeding a horizontal scanning period has elapsed. Video display device.

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