Patent Application
20080192343
The present invention contains subject matter related to Japanese Patent Application JP 2007-169408 filed with the Japan Patent Office on Jun. 27, 2007, the entire contents of which being incorporated herein by reference.
1. Field of the Invention
This invention relates to a three-dimensional image display apparatus which can display a stereoscopic image.
2. Description of the Related Art
In the past, a two-eye type stereoscopic image technique wherein both eyes of an observer observe images different from each other called parallax images to obtain a stereoscopic effect and a multi-eye type stereoscopic image technique wherein a plurality of sets of parallax images are prepared to obtain a plurality of stereoscopic images from different viewpoints are known in the past, and various techniques relating to such techniques have been and are being developed very much. However, according to the two-eye type stereoscopic image technique or the multi-eye type stereoscopic image technique, a stereoscopic image is positioned in an intended space as a stereoscopic image, but exists, for example, on a two-dimensional display plane and exists at a fixed position. Accordingly, particularly convergence and adjustment which are physiologic reactions of the ophthalmencephalon do not interlink with each other, and visual fatigue caused by this makes a problem.
Meanwhile, in the real world, information of the surface of a physical solid propagates to the eyeballs of the observer through a light wave serving as a medium. As a technique by which a light wave from the surface of a physical solid in the real world can be physically reproduced artificially, a holography technique is available. In a stereoscopic image which uses a holography technique, interference fringes generated by interference of light are used, and a diffracted light wave front itself which is generated when light is illuminated on the interference fringes is used as an image information medium. Therefore, an image with which such physiologic reactions of the optical system as convergence and adjustment similar to those when the observer observes a physical solid in the real world occurs and the visual fatigue is reduced can be provided. Further, that the light wave front from the physical solid is reproduced signifies that the continuity is assured in a direction in which image information is transmitted. Accordingly, even if the viewpoint of the observer moves, it is possible to successively present an appropriate image from the different angle according to the movement, and motion parallaxes are provided successively.
However, according to the holography technique, three-dimensional spatial information of a physical solid is recorded as interference fringes in a two-dimensional space, and the amount of information is very great when compared with that of information of a two-dimensional space on a picked up photograph of the same physical solid or the like. It is considered that this arises from the fact that, when information of a three-dimensional space is converted into information of a two-dimensional space, the information is converted into density in the two-dimensional space. Therefore, the spatial resolution necessary for a display device which displays interference fringes by CGH (Computer Generated Hologram) is very high, and a very great amount of information may be required. Therefore, in the existing condition, it is technically difficult to implement a stereoscopic image based on a real time hologram.
In the holography technique, light waves which can be regarded as continuous information are used as an information medium to transmit information from a physical solid. Meanwhile, as a technique of discretizing light waves and using light beams to reproduce a situation theoretically substantially equivalent to a field formed from light waves in the real world to produce a stereoscopic image, a light beam reproduction method or integral photography method is known. In the light beam reproduction technique, a light beam group composed of a large number of light beams propagating in many directions is scattered into a space by optical means in advance. Then, those light beams which are to be propagated from a virtual physical solid surface disposed at an arbitrary position are selected from the light beam group, and modulation of the intensity or phase of the selected light beams is carried out to generate an image formed from the light beams in the space. An observer can observe the image as a stereoscopic image. The stereoscopic image by the light beam reproduction method is formed at an arbitrary point from multiple images from a plurality of directions and can be observed in a different manner depending upon the position from which the stereoscopic image is observed similarly as in the case wherein a three-dimensional physical solid in the real world is observed.
As an apparatus for implementing the light beam reproduction described above, an apparatus has been proposed which utilizes a combination of a flat display apparatus such as a liquid crystal display apparatus or a plasma display apparatus and a microlens array or a pin-hole array. An apparatus of the type described is disclosed, for example, in Japanese Patent Laid-Open Nos. 2003-173128, 2003-161912, 2003-295114, 2003-75771, 2002-72135 and 2001-56450 and Japanese Patent No. 3,523,605. Also an apparatus has been proposed which includes a large number of projector units juxtaposed with each other.
According to the light beam reproduction method, since images are generated from light beams of an intensity with which they act effectively upon focal adjustment and binocular convergence angle adjustment as visual sensation functions, which have been impossible with two-eye and multi-eye type stereoscopic images, a stereoscopic image which provides very little fatigue to an observer can be provided. Besides, since light beams are continuously emitted in a plurality of directions from the same element on a virtual physical solid, the variation of the image upon movement of the viewpoint position can be provided continuously.
However, the image generated by the light beam reproduction technique at present lacks in provision of a sense of reality when compared with a physical solid in the real world. It is considered that this arises from the fact that the stereoscopic image by the light beam reproduction technique at present is generated from a much smaller amount of information, that is, from a much smaller amount of light beams, than the amount of information which the observer obtains from the physical solid in the real world. Generally, it is considered that the limit to visual observation of a human being is approximately a minute in angular resolution, and a stereoscopic image by the light beam reproduction method at present is produced from an amount of light beams insufficient to the visual sensation. Accordingly, in order to generate a stereoscopic image which provides such a high sense of reality or such reality as is provided by a physical solid in the real world, it is regarded as a subject at least to generate an image from a large amount of light beams.
In order to implement this, a technique may be required first which can generate a light beam group in a spatially high density. It is regarded as one of resolutions to raise the display density of a display apparatus such as a liquid crystal display apparatus. On the other hand, in such an apparatus as shown in
Further, for example, where a light source is formed from light emitting elements, if a dispersion in luminance occurs with the light emitting elements, then an image produced suffers from irregular luminance. As occasion demands, a variation occurs with the color tone of the image and makes a cause of quality deterioration of the image. The dispersion in luminance of the light emitting elements not only occurs upon attachment or assembly of the light source to the three-dimensional image display apparatus, but also occurs depending upon a secular change or a variation in operation environment.
Therefore, it is a desire to provide a three-dimensional image display apparatus which can generate and scatter a group of light beams necessary for display of a stereoscopic image in a spatially high density without increasing the overall size of the apparatus and can provide a stereoscopic image formed from light beams having quality proximate to that of a physical solid in the real world. Also it is a desire to provide a three-dimensional image display apparatus wherein the quality of an image to be displayed is not deteriorated even where a variation occurs with the intensity of light emitted from a light source.
According to a first embodiment of the present invention, there is provided a three-dimensional image display apparatus, including:
a light source configured to emit light from a plurality of light emitting positions disposed discretely;
optical modulation means for including a plurality of pixels and configured such that a plurality of light beams successively emitted from the different light emitting positions of the light source and having different incoming directions from each other are modulated individually by the pixels to generate two-dimensional images and spatial frequencies of the generated two-dimensional images are individually emitted along diffraction angles corresponding to a plurality of diffraction orders generated from the pixels; and
Fourier transform image forming means for Fourier transforming the spatial frequencies of the two-dimensional images emitted from the optical modulation means to produce a number of Fourier transform images corresponding to the plural number of diffraction orders to form the Fourier transform images.
Preferably, the three-dimensional image display apparatus further includes:
conjugate image forming means for forming a conjugate image of any of the Fourier transform images formed by the Fourier transform image forming means.
According to a second embodiment of the present invention, there is provided a three-dimensional image display apparatus, including:
a light source configured to emit light from a plurality of light emitting positions disposed discretely;
a two-dimensional image forming apparatus having a plurality of apertures arrayed in a two-dimensional matrix along an X direction and a Y direction and configured to control, for each of the apertures, passage or reflection of each of light beams successively emitted from the different light emitting positions of the light source and having different incoming directions from each other to produce two-dimensional images and generate, for each of the apertures, a plurality of diffraction light beams of different diffraction orders based on the two-dimensional images;
a first lens having a front side focal plane on which the two-dimensional image forming apparatus is disposed;
a second lens having a front side focal plane on which a rear side focal plane of the first lens is positioned; and
a third lens having a front side focal plane on which a rear side focal plane of the second lens is positioned.
In the three-dimensional image display apparatus according to the first embodiment of the present invention including the preferred form described above or according to the second embodiment of the present invention (the three-dimensional image display apparatus according to the first and second embodiments may sometimes be hereinafter referred to collectively as three-dimensional image display apparatus of the present invention), where the number of discretely disposed light emitting positions is represented by LEPTotal, the number of Fourier transform images formed from light beams individually emitted from the light emitting positions and having different incoming directions to the optical modulation means or the two-dimensional image forming apparatus (such light beams may sometimes be hereinafter referred to as illuminating light beams) is given by the (number of diffraction orders×LEPTotal). The Fourier transform images based on the illuminating light beams are formed as a spot at discrete positions corresponding to the light emitting positions by the Fourier transform image forming means or the first lens. It is to be noted that, if Fourier transform image selection means or a spatial filter is disposed, then the number of Fourier transform images formed from the illuminating light beams finally becomes, for example, LEPTotal. It is to be noted that, where the plural light emitting positions disposed discretely are disposed discretely or in a spaced relationship from each other in a two-dimensional matrix, the number of such light emitting positions is represented by U0×V0. Here, U0×V0=LEPTotal.
The three-dimensional image display apparatus may be configured such that the light source includes a plurality of light emitting elements arrayed in a two-dimensional matrix. It is to be noted that, in this instance, if the number of the light emitting elements arrayed in a two-dimensional matrix is U0′×V0′, then the values of U0′×V0′ may be U0′=U0′ and V0′=V0 or, for example, U0′/3=U0 and V0′/3=V0 depending upon the specifications of the light source. In this instance, preferably the three-dimensional image display apparatus further includes a lens such as, for example, a collimator lens interposed between the light source and the optical modulation means or the two-dimensional image forming apparatus such that the light source is positioned on or in the proximity of a front side focal plane of the lens. This is because the light or illuminating light emitted from the lens is converted into parallel light or substantially parallel light. Or, the three-dimensional image display apparatus may be configured such that the light source includes a light emitting element and light beam advancing direction changing means for changing the incoming direction of light emitted from the light emitting element and directed to be introduced to the optical modulation means. In this instance, the light beam advancing direction changing means may be refraction type optical means which can vary or change the incoming direction of the light beams to be emitted with respect to the incoming light beams such as, for example, a lens, more particularly a collimator lens or a microlens array. Or, the light beam advancing direction changing means may be reflection type optical means which can vary or change the position and the angle of the light beams to be emitted with respect to the incoming light beams such as, for example, a mirror, more particularly a polygon mirror, a combination of a polygon mirror and a mirror, a convex mirror having a curved face, a concave mirror having a curved face, a convex mirror formed from a polygon or a concave mirror formed from a polygon.
Where the light source includes a plurality of light emitting elements arrayed in a two-dimensional matrix as described above, preferably the light emitting elements are disposed so that the emitting directions of light beams to be emitted from the light emitting elements are different from each other and the incoming directions of the light beams to the optical modulation means or the two-dimensional image forming apparatus are different from each other. Further, where refraction type optical means is adopted as the light beam advancing direction changing means, preferably the light source includes a plurality of light emitting elements arrayed in a two-dimensional matrix. In this instance, since the emitting direction of the light beams successively emitted from the light emitting elements and coming to the refractive type optical section when the light beams go out from the refractive type optical section can be changed by the refractive type optical section, the incoming direction of the light beams when they are introduced into the optical modulation means or the two-dimensional image forming apparatus can be changed. It is to be noted that the outgoing directions of the light beams to be emitted individually from the light emitting elements may be same as each other or different from each other. On the other hand, where reflection type optical means is adopted as the light beam advancing direction changing means as described above, the number of light emitting elements may be one or, for example, U0. Then, the number of the light emitting positions at which the light beams are to be emitted from the reflection light optical means may be set to U0×V0=LEPTotal by controlling the position or the like of the reflection type optical means. In particular, for example, the inclination angle of an axis of rotation of a polygon mirror is controlled while the polygon mirror is rotated around the axis of rotation. Or, the position of the light beams to be introduced to the mirror from the light emitting elements may be controlled. Or else, the state of the illuminating light to be emitted from the mirror, for example, passage or interception of the illuminating light, may be controlled. The incoming direction of the light beams to be introduced to the optical modulation means or the two-dimensional image forming apparatus can be changed thereby.
The three-dimensional image display apparatus according to the first embodiment of the present invention including the preferred configurations and forms described above may be configured such that the Fourier transform image forming means includes a lens or first lens having a front side focal plane on which the optical modulation means is disposed.
In the three-dimensional image display apparatus according to the first embodiment of the present invention, while images produced and formed by the Fourier transform image forming means correspond to a plurality of diffraction orders, an image obtained based on comparatively low order diffraction is comparatively bright and an image obtained based on comparatively high order diffraction is comparatively dark. Therefore, a stereoscopic image of sufficiently high picture quality can be obtained. However, in order to achieve higher picture quality, preferably the three-dimensional image display apparatus further includes:
Fourier transform image selection means disposed at a position at which the Fourier transform images are formed and for selecting, from among the number of Fourier transform images corresponding to the plural number of diffraction orders generated by the Fourier transform image forming means, a Fourier transform image which corresponds to a desired one of the diffraction orders.
Also in the three-dimensional image display apparatus according to the second embodiment of the present invention, while images produced and formed by the first lens correspond to a plurality of diffraction orders, an image obtained based on comparatively low order diffraction is comparatively bright and an image obtained based on comparatively high order diffraction is comparatively dark. Therefore, a stereoscopic image of sufficiently high picture quality can be obtained. However, in order to achieve higher picture quality, preferably the three-dimensional image display apparatus further includes:
a spatial filter having a number of apertures corresponding to the number of the light emitting positions and capable of being controlled to open and close, the spatial filter being positioned on the rear side focal plane of the first lens.
In this instance, preferably the three-dimensional image display apparatus is configured such that the spatial filter makes a desired one of the apertures into an open state in synchronism with a generation timing of a two-dimensional image by the two-dimensional image forming apparatus. Or, preferably the three-dimensional image display apparatus further includes:
a scattering diffraction restriction member having a number of apertures corresponding to the number of the light emitting positions and positioned on the rear side focal plane of the first lens.
Where the spatial filter or the scattering diffraction restriction member is disposed, only a desired one or ones of the produced diffraction light beams of the diffraction orders can be passed through the same.
In those instances, the Fourier transform image selection means or the spatial filter has a number of apertures corresponding to the number of the light emitting positions, that is, LEPTotal equal to, for example, U0×V0. Each of the apertures may be controllable between on and off states or may normally be in an open state. The Fourier transform image selection means or the spatial filter which has apertures which can be controlled between open and closed states may be a liquid crystal display apparatus, particularly a liquid crystal display apparatus of the transmission type or the reflection type or a MEMS of the two-dimensional type wherein movable mirrors are arrayed in a two-dimensional matrix. The Fourier transform image selection means or the spatial filter which has apertures which can be controlled between open and closed states may be configured such that it makes a desired one of the apertures into an open state in synchronism with a generation timing of a two-dimensional image by the optical modulation means or the two-dimensional image forming apparatus to select one of the Fourier transform images or the diffraction light beams which corresponds to the desired diffraction order. The position of each aperture may be the position at which a desired Fourier transform image or a desired diffraction light beam from among the Fourier transform images or the diffraction light beams obtained by the Fourier transform image selection means or the first lens, and such positions of the apertures correspond to the light emitting positions disposed discretely.
Preferably, the three-dimensional image display apparatus according to the first embodiment of the present invention including the preferred forms and configurations described above further includes inverse Fourier transform means for inversing Fourier transform any of the Fourier transform images formed by the Fourier transform image forming means to form a real image of the two-dimensional image formed by the optical modulation means.
Further, the three-dimensional image display apparatus according to the first embodiment of the present invention including the preferred forms and configurations described above may be configured such that the optical modulation means includes a two-dimensional spatial optical modulator having a plurality of pixels (P×Q) arrayed two-dimensionally, each of the pixels having an aperture. In this instance, preferably the two-dimensional spatial optical modulator is formed from a liquid crystal display apparatus, more particularly a liquid crystal display apparatus of the transmission type or the reflection type, or is configured such that a movable mirror is provided in each aperture of the two-dimensional spatial optical modulator, that is, it is formed from a two-dimensional type MEMS wherein movable mirrors are arrayed in a two-dimensional matrix. Further, in the three-dimensional image display apparatus according to the second embodiment including the preferred configurations and forms described above, the two-dimensional image forming apparatus may be formed such that it is formed from a liquid crystal display apparatus, more particularly a liquid crystal display apparatus of the transmission type or the reflection type, having a plurality of, that is, P×Q, pixels arrayed two-dimensionally and each having an aperture. Or, the two-dimensional image forming apparatus may otherwise be formed such that it has a plurality of, that is, P×Q, apertures and a movable mirror is provided in each of the apertures, that is, it is formed from a two-dimensional type MEMS wherein a movable mirror is disposed in each of apertures arrayed in a two-dimensional matrix. Here, preferably the apertures have a rectangular planar shape. Where the rectangular planar shape is adopted for the apertures, Fraunhofer diffraction occurs to produce M×N diffraction light beams. In particular, the amplitude or intensity of the incident light wave is periodically modulated by the apertures, and amplitude gratings from which a light amount distribution conforming to the light transmission factor distribution of gratings can be obtained are formed.
Further, the three-dimensional image display apparatus according to the first embodiment of the present invention including the preferred forms and configurations described above may be configured such that the spatial frequencies of the two-dimensional images correspond to image information whose carrier frequency is the spatial frequency of the pixel structure. Further, the three-dimensional image display apparatus may be configured such that the spatial frequencies of a conjugate image of a two-dimensional image hereinafter described are spatial frequencies obtained by removing the spatial frequency of the pixel structure from the spatial frequencies of the two-dimensional image. In particular, those spatial frequencies, obtained as the 1st order diffraction where the 0th order diffraction of plane wave component is a carrier frequency, lower than one half the spatial frequency of the pixel structure or aperture structure of the optical modulation means are selected by the Fourier transform image selection means or the spatial filter, or those spatial frequencies which pass through the Fourier transform image selection means or the spatial filter and are displayed on the optical modulation means or the two-dimensional image forming apparatus are all transmitted.
Preferably, the three-dimensional image display apparatus according to the present embodiment including the preferred forms and configurations described above further includes light detection means for measuring the light intensity of the light beams successively emitted from the different light emitting positions of the light source. Then, the light emitting state of the light source may be controlled or an operation state of the optical modulation means or the two-dimensional image forming apparatus may be controlled, based on a result of the measurement of the light intensity by the light detection means.
The light detection means may be a photodiode, a CCD or a CMOS sensor. A beam splitter or a partially reflecting mirror or partial reflector may be interposed between the light source and the optical modulation means or the two-dimensional image forming apparatus so that part of light which is emitted from the light source and directed to the optical modulation means or the two-dimensional image forming apparatus is extracted and introduced to the light detection means. Or, a partially reflecting mirror may be disposed rearwardly of the Fourier transform image forming means or the two-dimensional image forming apparatus so that part of light emitted from the Fourier transform image forming means or the two-dimensional image forming apparatus is extracted and introduced to the light detection means. Or else, the light detection means may be attached to the optical modulation means or the two-dimensional image forming apparatus, or the light detection means may be incorporated in the light source such that particularly it is disposed, for example, in the proximity of each of the light emitting elements which form the light source or is incorporated in each of the light emitting elements. Or otherwise, the light detection means may be disposed at any position at which it does not intercept light which passes through an effective region from the light source to the optical modulation means or two-dimensional image forming apparatus, the Fourier transform image forming means or a succeeding component.
In the three-dimensional image display apparatus according of the present embodiment including the preferred forms and configurations described above, as regards the numbers of U0 and V0, the number of U0 may be 4≦U0≦12, preferably, for example, 9≦U0≦11 though not restricted to them. Meanwhile, the number of V0 may be 4≦V0≦12, preferably, for example, 9≦V0≦11. The value of U0 and the value of V0 may be equal to or different from each other. It is to be noted that a plane, that is, an XY plane, on which Fourier transform images are formed by the Fourier transform image forming means is hereinafter referred to sometimes as image forming plane.
In a preferred form of the three-dimensional image display apparatus of the present embodiment, a Fourier transform image corresponding to a desired diffraction order is selected by the Fourier transform image selection means or the spatial filter or passes through the Fourier transform image selection means or the spatial filter. Here, the desired diffraction order may be the 0th diffraction order although it is not limited to this order.
The light source in the three-dimensional image display apparatus according the present embodiment including the various preferred forms and configurations described above may be a laser, a light emitting diode (LED) or a white light source. An illuminating optical system for shaping illuminating light may be disposed between the light source and the optical modulation means or the two-dimensional image forming apparatus. Depending upon the specification of the three-dimensional image display apparatus, single color light such as, for example, light from a red light emitting diode, a green light emitting diode or a blue light emitting diode or white light such as, for example, light from a white light emitting diode may be emitted from the light source. Or the light source may include a red light emitting element, a green light emitting element and a blue light emitting element such that light which is red light, green light or blue light is emitted from the light source by successively driving the light emitting elements. Also by this, illuminating light beams which are emitted from the plural light emitting positions disposed discretely and have different incoming directions to the optical modulation means or the two-dimensional image forming apparatus can be obtained.
In a liquid crystal display apparatus which forms the two-dimensional spatial optical modulator or the two-dimensional image forming apparatus, for example, a region within which a transparent first electrode and a transparent second electrode described below overlap with each other and which includes a liquid cell corresponds to one pixel. Then, the liquid crystal cell is caused to operate as a kind of a light shatter or light valve, that is, the light transmission factor or numerical aperture of each pixel is controlled, to control the light transmission factor of the illuminating light emitted from the light source thereby to obtain a two-dimensional image as a whole. A rectangular aperture is provided in the overlapping region of the transparent first and second electrodes, and as the illuminating light emitted from the light source passes through each aperture, Fraunhofer diffraction occurs with each pixel. Consequently, totaling M×N sets of diffraction light beams are generated.
A liquid crystal display apparatus typically includes a front panel having a transparent first electrode provided thereon, a rear panel having a transparent second electrode provided thereon, and liquid crystal material disposed between the front and rear panels. The front panel particularly includes a first substrate formed typically from a glass substrate or a silicon substrate, a transparent first electrode made of, for example, ITO and provided on an inner face of the first substrate, and a polarizing film provided on an outer face of the first substrate. The transparent first electrode is called also common electrode. Further, an orientation film is provided on the transparent first electrode. Meanwhile, the rear panel particularly includes a second substrate formed typically from a glass substrate or a silicon substrate, a switching element formed on an inner face of the second substrate, a transparent second electrode made of, for example, ITO and controlled between a conducting state and a non-conducting state by the switching element, and a polarizing film provided on an outer face of the second substrate. The transparent second electrode is called also pixel electrode. An orientation film is formed over the overall area including the transparent second electrode. The materials of the components and the liquid crystal material of the liquid crystal display apparatus of the transmission type may be known materials or members. It is to be noted that the switching element may be a three-terminal element such as a MOS FET or a thin film transistor (TFT) or a two-terminal element such as a MIM element, a barrister element or a diode formed on a single crystal silicon semiconductor substrate. Or, the liquid crystal display apparatus may have a matrix electrode configuration wherein a plurality of scanning electrodes extend in a first direction and a plurality of data electrodes extend in a second direction. In a liquid crystal display apparatus of the transmission type, illuminating light from the light source enters from the second substrate and goes out from the first substrate. On the other hand, in a liquid crystal display apparatus of the reflection type, illuminating light from the light source enters from the first substrate and is reflected by the second electrode (pixel electrode) formed on the inner face of the second substrate, whereafter it goes out from the first substrate. The apertures can be formed, for example, by forming an insulating material layer opaque to the illuminating light from the light source between the transparent second electrode and the associated orientation film and forming apertures in the insulating material layer. It is to be noted that the liquid crystal display apparatus of the reflection type may be a liquid crystal display apparatus of the LCOS (Liquid Crystal on Silicon) type.
The three-dimensional image display apparatus of the present embodiment may include an optical section for projecting the conjugate image formed by the conjugate image forming means or may include an optical section provided rearwardly of the third lens for projecting an image formed by the third lens.
In the three-dimensional image display apparatus of the present embodiment, where the number P×Q of pixels of a two-dimensional image is represented by (P, Q), several values of the resolution for image display can be used as the values of (P. Q) such as VGA (640, 480), S-VGA (800, 600), XGA (1,024, 768), APRC (1,152, 900), S-XGA (1,280, 1,024), U-XGA (1,600, 1,200), HD-TV (1,920, 1,080), and Q-XGA (2,048, 1,536) as well as (1,920, 1,035), (720, 480) and (1,280, 960). However, the values of (P×Q) are not limited to any of the above-specified values.
In summary, in the three-dimensional image display apparatus according to the first or second embodiment of the present invention, two-dimensional images are produced by the optical modulation means or the two-dimensional image forming apparatus based on light beams or illuminating light beams successively emitted from the different light emitting positions of the light source and having different incoming directions from each other. Further, spatial frequencies of the produced two-dimensional images are emitted along a plurality of diffraction angles corresponding to different diffraction orders generated from each of the pixels or the like. Then, the spatial frequencies are Fourier transformed by the Fourier transform image forming means or the first lens to produce and form a number of Fourier transform images or diffraction light beams corresponding to the number of diffraction orders thereby to finally reach an observer. The image which finally reaches the observer includes components of the incoming directions of the light beams or illuminating light beams to the optical modulation means or the two-dimensional image forming apparatus. Then, as such operations as described above are successively repeated in a time series, a group of light beams, for example, LEPTotal light beams, emitted from the Fourier transform image forming means or the first lens can be produced and scattered in a spatially very high density and besides in a state distributed in a plurality of directions. As a result, a stereoscopic image of a texture proximate to that of a physical solid in the real world can be obtained from the light beam group based on a light beam reproduction method, which is not available in the past and efficiently controls directional components of light beams for forming a stereoscopic image, without giving rise to increase of the overall size of the three-dimensional image display apparatus.
Besides, in the three-dimensional image display apparatus of the present embodiment, if a stereoscopic image is formed based on 0th-order diffraction light, then a bright and clear stereoscopic image of high quality can be obtained.
Further, where the light detection means is provided, the light emitting state of the light source can be monitored. Consequently, it is possible to suppress occurrence of quality deterioration of the picture quality arising from a dispersion of the light emitting state or from a secular change.
The above and other desire, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols.
In the following, the present invention is described in connection with working examples thereof shown in the accompanying drawings.
The working example 1 of the present invention is directed to a three-dimensional image display apparatus according to first and second embodiments of the present invention.
In display of a stereoscopic image by a light beam reproduction method in the related art, in order to emit a plurality of beams of light from a virtual origin on the surface of a virtual physical solid existing at an arbitrary position, it is necessary to prepare an apparatus which can provide beams of light which are emitted at various angles in advance. For example, in an apparatus shown in
Meanwhile, in the three-dimensional image display apparatus 1 of the working example 1, the three-dimensional image display apparatus itself which includes such components as seen in
Where the three-dimensional image display apparatus 1 of the working example 1 is described in connection with components of the three-dimensional image display apparatus according to the first embodiment of the present invention, it includes:
a light source 10 configured to emit light from a plurality of light emitting positions disposed discretely or spaced from each other;
an optical modulation section 30 including a plurality of (P×Q) pixels 31 and configured such that light beams or illuminating light beams successively emitted from the different light emitting positions of the light source 10 and incoming in different directions from each other are modulated by the pixels 31 to generate two-dimensional images and spatial frequencies of the generated two-dimensional images are emitted along diffraction angles corresponding to a plurality of (totaling M×N) diffraction orders generated from the pixels 31; and
a Fourier transform image forming section 40 configured to Fourier transform the spatial frequencies of the two-dimensional images emitted from the optical modulation section 30 to produce a number of Fourier transform images corresponding to the number of (totaling M×N) diffraction orders to form the Fourier transform images; as well as
a conjugate image forming section 60 configured to form conjugate images of the Fourier transform images formed by the Fourier transform image forming section 40.
Where the three-dimensional image display apparatus 1 of the working example 1 is described in connection with components of the three-dimensional image display apparatus according to the second embodiment of the present invention, it includes:
a light source 10 configured to emit light from a plurality of light emitting positions disposed discretely or spaced from each other;
a two-dimensional image forming apparatus 30 having P×Q apertures arrayed in a two-dimensional matrix along an X direction and a Y direction and configured to control passage for each of the apertures of light beams or illuminating light beams successively emitted from the different light emitting positions of the light source 10 and having different incoming directions to produce two-dimensional images and generate a plurality of (totaling M×N) diffraction light beams of different diffraction orders for each of the apertures based on the two-dimensional images;
a first lens L1 having a front side focal plane, which is a focal plane on the light source side, on which the two-dimensional image forming apparatus 30 is disposed;
a second lens L2 having a front side focal plane, which is a focal plane on the light source side, on which the rear side focal plane, which is a focal plane on the observer side, of the first lens L1 is positioned; and
a third lens L3 having a front side focal plane on which the rear side focal plane of the second lens L2 is positioned.
Here, the spatial frequencies of the two-dimensional images correspond to image information having a carrier frequency equal to the spatial frequency of the pixel structure.
In the three-dimensional image display apparatus 1 of the working example 1, the light source 10 includes light emitting elements 11, and light advancing direction changing means for changing the incoming direction of light emitted from the light emitting element 11 and directed so as to enter optical modulation means or two-dimensional image forming apparatus 30. Here, the light source 10 includes a plurality of light emitting elements 11 each in the form of a light emitting diode or LED which are arrayed in a two-dimensional matrix. It is to be noted that the number of light emitting elements 11 arrayed in a two-dimensional matrix is U0′×V0′ and the number of light emitting positions disposed discretely on the light source 10 is U0×V0 (where U0=U0′ and V0=V0′). In the working example 1, P=1,024 and Q=768, and U0=11 and V0=11. It is to be noted that the numbers of the light emitting elements 11 and the light emitting positions are not limited to the specific numbers. Further, the light advancing direction changing means is formed from refraction type optical means, particularly a lens, and more particularly a collimator lens 12. Here, the light emitting elements 11 are disposed in the proximity of the front side focal plane of the collimator lens 12 so that the emitting direction when light beams in the form of parallel light beams emitted from the light emitting elements 11 and incoming to the collimator lens 12 go out from the collimator lens 12 can be changed stereoscopically. As a result, the incoming angles of light beams or illuminating light beams incoming from the optical modulation means or two-dimensional image forming apparatus 30 can be changed stereoscopically (refer to
The z axis which corresponds to the optical axis passes the center of the components of the three-dimensional image display apparatus 1 of the working example 1 and besides intersects perpendicularly with the components of the three-dimensional image display apparatus 1. If the components of the three-dimensional image display apparatus according to the first embodiment of the present invention and the components of the three-dimensional image display apparatus according to the second embodiment of the present invention are compared with each other, then the optical modulation section 30 corresponds the two-dimensional image forming apparatus 30; the Fourier transform image forming section 40 corresponds to the first lens L1; a Fourier transform image selection section 50 hereinafter described corresponds to a spatial filter SF; the inverse Fourier transform means corresponds to the second lens L2; and the conjugate image forming section 60 corresponds to the second lens L2 and the third lens L3. Therefore, for the convenience of description, the following description is given using the terms of the two-dimensional image forming apparatus 30, first lens L1, spatial filter SF, second lens L2 and third lens L3.
A state wherein fluxes of light emitted from light emitting elements 11A, 11B and 11C which compose the light source 10 pass through the two-dimensional image forming apparatus 30, first lens L1 and spatial filter SF is schematically illustrated in
As described hereinabove, the collimator lens 12 is disposed between the light emitting elements 11 and the two-dimensional image forming apparatus 30. The two-dimensional image forming apparatus 30 is illuminated with illuminating light beams emitted from the light emitting elements 11 and passing through the collimator lens 12. However, the incoming direction of the illuminating light beams to the two-dimensional image forming apparatus 30 differs stereoscopically depending upon the two-dimensional positions (light emitting positions) of the light emitting elements 11.
The optical modulation section 30 is formed from a two-dimensional spatial optical modulator having a plurality of pixels 31 arrayed two-dimensionally, and each of the pixels 31 has an aperture. Here, the two-dimensional spatial optical modulator or two-dimensional image forming apparatus 30 is particularly formed from a liquid crystal display apparatus of the transmission type having P×Q pixels 31 disposed two-dimensionally, that is, disposed in a two-dimensional matrix along the X direction and the Y direction, and each of the pixels 31 has an aperture. It is to be noted that the shape of the aperture in plan is a rectangular shape. Where the apertures have a rectangular planar shape, Fraunhofer diffraction occurs and M×N diffraction light beams are produced. In particular, by such apertures, the amplitude (intensity) of the incoming light waves is modulated periodically such that amplitude gratings from which a light amount distribution coincident with a light transmission factor distribution of gratings are formed.
One pixel 31 is formed from a region in which a transparent first electrode and a transparent second electrode overlap with each other and which includes a liquid crystal cell. Then, the liquid crystal cell operates as a kind of optical shutter or light valve, that is, the light transmission factor or numerical aperture of each pixel 31 is controlled, to control the light transmission factor of the illuminating light emitted from the light source 10, and as a whole, a two-dimensional image is obtained. A rectangular aperture is provided in the overlapping region of the transparent first and second electrodes, and when the illuminating light emitted from the light source 10 passes through the aperture, Fraunhofer diffraction occurs. As a result, M×N diffraction light beams are generated from each of the pixels 31. In other words, since the number of pixels 31 is P×Q, it is considered that totaling P×Q×M×N diffraction light beams are generated. In the two-dimensional image forming apparatus 30, spatial frequencies of a two-dimensional image are emitted along diffraction angles corresponding to a plurality of diffraction orders, totaling M×N orders, generated from each pixel 31. It is to be noted that the diffraction angles differ also depending upon the spatial frequencies of the two-dimensional image.
In the three-dimensional image display apparatus 1 of the working example 1, the Fourier transform image forming section 40 is formed from a lens, that is, the first lens L1, and the two-dimensional image forming apparatus 30 is disposed on the front side focal plane, which is the focal plane on the light source side, of this lens, that is, the first lens L1.
The three-dimensional image display apparatus 1 of the working example 1 includes a Fourier transform image selection section 50 for selecting a Fourier transform image corresponding to a desired diffraction order from among a number of generated Fourier transform images corresponding to a plural number of diffraction orders. Here, the Fourier transform image selection section 50 is disposed at a position at which Fourier transform images are formed, that is, an XY plane or an image forming plane on which Fourier transform images are formed by the Fourier transform image forming section 40. In particular, the Fourier transform image selection section 50 is disposed on the rear side focal plane, that is, on the focal plane on the observer side, of the lens which forms the Fourier transform image forming section 40, that is, the first lens L1. Or, in other words, the three-dimensional image display apparatus 1 includes a spatial filter SF having a number of apertures 51, which can be controlled to be opened and closed, corresponding to the number of light emitting positions of the light source 10 and positioned on the rear side focal plane of the first lens L1. In particular, the Fourier transform image selection section 50 or spatial filter SF has a number of (U0×V0=LEPTotal) apertures 51 corresponding to the number (U0×V0=LEPTotal) of light emitting positions of the light source 10 disposed discretely.
Here, the Fourier transform image selection section 50 or spatial filter SF can be formed more particularly from a liquid crystal display apparatus of the transmission type or the reflection type which uses dielectric liquid crystal having, for example, U0×V0 pixels or a MEM of the two-dimensional type including an apparatus wherein movable mirrors are arrayed two-dimensionally. Here, for example, opening and closing control of the apertures 51 can be carried out by causing the liquid crystal cell to operate as a kind of optical shutter or light valve or by movement/non-movement of the movable mirrors. In the Fourier transform image selection section 50 or spatial filter SF, a Fourier transform image corresponding to a desired diffraction order (0th order) can be selected by placing a desired aperture 51 (particularly an aperture 51 through which 0th order diffraction light is to pass) into an open state in synchronism with a production timing of a two-dimensional image by the two-dimensional image forming apparatus 30.
The three-dimensional image display apparatus 1 further includes inverse Fourier transform means, particularly the second lens L2, for inverse Fourier transforming a Fourier transform image formed by the Fourier transform image forming section 40 to form a real image R1 of a two-dimensional image formed by the two-dimensional image forming apparatus 30.
In the working example 1, each of the first lens L1, second lens L2 and third lens L3 is particularly formed from a convex lens.
As described hereinabove, the two-dimensional image forming apparatus 30 is disposed on the front side focal plane, that is, the focal plane on the light source side, of the first lens L1 having the focal distance f1, and the spatial filter SF which can be temporally controlled to open and close for spatially and temporally filtering a Fourier transform image is disposed on the rear side focal plane, that is, the focal plane on the observer side, of the first lens L1. Then, a number of Fourier transform images corresponding to a plural number of diffraction orders are produced by the first lens L1, and the Fourier transform images are formed on the spatial filter SF. It is to be noted that, in
A schematic front elevational view of the light source 10 formed from a plurality of light emitting elements arrayed in a two-dimensional matrix is shown in
The planar shape of the apertures 51 of the spatial filter SF may be determined based on the shape of the Fourier transform images. Further, the apertures 51 may be provided, for example, for Fourier transform images corresponding to the 0th order diffraction such that the peak position of a plane wave component of a Fourier transform image may be the center. As a result, a peak of the light intensity of a Fourier transform image is positioned at the central position of each aperture 51. In particular, the apertures 51 may be formed such that all of the positive and negative highest spatial frequencies of a two-dimensional image can pass therethrough centering on a periodical pattern of Fourier transform images where the spatial frequency of the two-dimensional image is the lowest spatial frequency component or plane wave component.
As described above, the conjugate image forming section 60 is particularly formed from the second lens L2 and the third lens L3. The second lens L2 having the focal distance f2 inverse Fourier transforms a Fourier transform image filtered by the spatial filter SF to form a real image RI of the two-dimensional image formed by the two-dimensional image forming apparatus 30. In particular, the second lens L2 is disposed such that the real image RI of the two-dimensional image formed by the two-dimensional image forming apparatus 30 is formed on the rear side focal plane of the second lens L2. The magnification of the real image RI obtained here with respect to the two-dimensional image of the two-dimensional image forming apparatus 30 can be varied by arbitrarily selecting the focal distance f2 of the second lens L2. Further, the third lens L3 having the focal distance f3 forms a conjugate image CI of the Fourier transform image filtered by the spatial filter SF.
Here, since the rear side focal plane of the third lens L3 is a conjugate plane of the spatial filter SF, this is equivalent to that the two-dimensional image produced by the two-dimensional image forming apparatus 30 is outputted from a portion on the spatial filter SF corresponding to one of the apertures 51. Then, the amount of light beams to be outputted corresponds to the number of pixels (P×Q) and to the number of light beams which pass through the spatial filter SF. In particular, the situation that the amount of light beams which pass through the spatial filter SF is decreased by later passage or reflection of the light through or by a component of the two-dimensional image display apparatus does not substantially occur. Further, although the conjugate image CI of the Fourier transform image is formed on the rear side focal plane of the third lens L3, since directional components of the conjugate image of the two-dimensional image are defined by directional components of illuminating light emitted from the light source 10 and incoming to the two-dimensional image forming apparatus 30, it can be regarded that the light beams are disposed regularly two-dimensionally on the rear side focal plane of the third lens L3. In other words, this is generally equivalent to a state that a plurality of (U0×V0) projector units 101 shown in
As schematically shown in
The spatial frequencies of the two-dimensional image on which all image information of the two-dimensional image formed by the two-dimensional image forming apparatus 30 is intensified are Fourier transformed by the first lens L1 to produce a number of Fourier transform images corresponding to a plural number of diffraction orders produced from each pixel 31. Then, only a predetermined Fourier transform image, for example, a Fourier transform image corresponding to the 0th order diffraction, from among the Fourier transform images, is passed through the spatial filter SF. Then, the selected Fourier transform image is inverse Fourier transformed by the second lens L2 to form a conjugate image of the two-dimensional image produced by the two-dimensional image forming apparatus 30. The conjugate image of the two-dimensional image enters the third lens L3, by which a conjugate image CI is formed. It is to be noted that, while the spatial frequencies of the two-dimensional image correspond to image information whose carrier frequency is the spatial frequency of the pixel structure, only a region of the image information whose carrier is a 0th order plane wave, that is, a region up to a spatial frequency equal to ½ the spatial frequency of the pixel structure in the maximum, is obtained as 1st order diffraction where the 0th order diffraction of the pixel structure is the carrier frequency, and the spatial frequencies lower than one half the spatial frequency of the pixel structure or aperture structure of the optical modulation means pass through the spatial filter SF. In this manner, the conjugate image of the two-dimensional structure formed by the third lens L3 does not include the pixel structure of the two-dimensional image forming apparatus 30, but includes all spatial frequencies of the two-dimensional image produced by the two-dimensional image forming apparatus 30. Then, since a Fourier transform image of the spatial frequency of the conjugate image of the two-dimensional image is produced by the third lens L3, Fourier transform images can be formed in a spatially high density.
In the following, the timing of opening and closing control of the apertures 51 of the spatial filter SF is described.
In the spatial filter SF, in order to select a Fourier transform image corresponding to a desired diffraction order, opening and closing control of the apertures 51 is carried out in synchronism with outputting of an image from the two-dimensional image forming apparatus 30. This operation is described with reference to
It is assumed that, as seen in
Images obtained as a final output of the three-dimension image display apparatus 30 where image formation and opening and closing control of the apertures 51 of the two-dimensional image forming apparatus 30 are carried out at such timings as described above are schematically shown in
In particular, as described hereinabove, for example, the images A′, B′, C′, . . . are successively outputted in a time series from the rear side focal plane of the third lens L3. In particular, this is equivalent to that generally a plural number of projector units shown in
The opening and closing control of the apertures 51 provided on the spatial filter SF may not be carried out for all apertures 51. In particular, the opening and closing control of the apertures 51 may be carried out, for example, for every other one of the apertures 51 or for those of the apertures 51 which are positioned at a desired position.
As described above, with the three-dimensional image display apparatus 1 of the working example 1, while a predetermined one of the light emitting elements 11 is turned on to emit light, a desired one of the apertures 51 of the Fourier transform image selection section 50 or spatial filter SF is opened. Accordingly, spatial frequencies of a two-dimensional image produced by the two-dimensional image forming apparatus 30 are emitted along a plurality of diffraction angles corresponding to different diffraction orders and Fourier transformed by the Fourier transform image forming section 40 or first lens L1. Then, Fourier transform images obtained by such Fourier transform are filtered spatially and temporally by the Fourier transform image selection section 50 or spatial filter SF, and a conjugate image CI of the filtered Fourier transform image is formed. Consequently, a group of beams of light can be produced and scattered in a state wherein they are distributed in a plurality of directions in a spatially high density without inviting upsizing of the entire three-dimensional image display apparatus. Further, the individual beams of light which are components of the group of light beams can be temporally and spatially controlled independently of each other. Consequently, a stereoscopic image formed from beams of light proximate in quality to those of a physical solid in the real world can be obtained.
Further, with the three-dimensional image display apparatus 1 of the working example 1, since a light beam reproduction method is utilized, a stereoscopic image which satisfies such visual sensation functions as focal adjustment, convergence and motion parallax can be provided. Further, with the three-dimensional image display apparatus 1 of the working example 1, since illuminating light beams whose incoming directions to the two-dimensional image forming apparatus 30 differ depending upon a plurality of light emitting positions disposed discretely or in a spaced relationship from each other, when compared with the image outputting technique in the past, the number of light beams which can be controlled by a single image outputting device, that is, the two-dimensional image forming apparatus 30, can be made equal to the number of light emitting positions disposed discretely, that is, to U0×V0. Besides, with the three-dimensional image display apparatus 1 of the working example 1, since filtering is carried out spatially and temporally, a temporal characteristic of the three-dimensional image display apparatus can be converted into a spatial characteristic of the three-dimensional image display apparatus. Further, a stereoscopic image can be obtained without using a diffusion screen or the like. Furthermore, a stereoscopic image which looks appropriately from whichever direction it is observed can be provided. Further, since a group of light beams can be produced and scattered in a spatially high density, a spatial image of a high definition near to a visual confirmation limit can be provided.
The working example 2 is a modification to the working example 1. The three-dimensional image display apparatus of the working example 2 is schematically shown in
In the three-dimensional image display apparatus of the working example 2 shown in
It is to be noted that a configuration wherein a movable mirror is provided in each aperture, that is, a configuration formed from a two-dimensional type MEMS wherein movable mirrors are disposed in a two-dimensional matrix, can be adopted alternatively as the optical modulation means or two-dimensional image forming apparatus of the reflection type. In this instance, a two-dimensional image is formed by movement/non-movement of the movable mirrors, and besides, Fraunhofer diffraction is caused by the apertures. It is to be noted that, where a two-dimensional type MEMS is adopted, a beam splitter is not required, but illuminating light may be introduced in an oblique direction into the two-dimensional type MEMS.
The working example 3 is a modification to the working example 1 and includes a light detection section 80 for measuring the intensity of light beams successively emitted from different light emitting positions of the light source 10. In particular, in the working example 3, the light detection section 80 is formed from a photodiode. As seen in
Or, a partially reflecting mirror 82 may be disposed rearwardly of the spatial filter SF or Fourier transform image selection section 50, more particularly, rearwardly of the second lens L2 as seen in
Further, the light emitting state of the light source 10 is controlled based on a result of measurement of the light intensity by the light detection section 80. In particular, as seen from
The light emitting state of a light emitting element 11 is measured by the light detection section 80 formed from a photodiode, and an output of the light detection section 80 is inputted to the light detection section control circuit 95. The light detection section control circuit 95 converts the received output of the control circuit 90 into data or a signal representing, for example, a luminance and a chromaticity of the light emitting element 11. The data is sent to the light source control circuit 93, by which it is compared with reference data. Then, the light emitting state of the light emitting element 11 upon subsequently light emission is controlled based on a result of the comparison by the light emitting element driving circuit 94 under the control of the light source control circuit 93. In this manner, a feedback control mechanism is formed from the elements mentioned. Further, a resistor r for current detection is inserted in series to the light emitting element 11 on the downstream side of the light emitting element 11 such that current flowing therethrough is converted into a voltage. Then, operation of a light emitting element driving power supply 96 is controlled so that the voltage drop across the resistor r may have a predetermined value under the control of the light source control circuit 93.
Or, the operation state of the two-dimensional image forming apparatus 30 is controlled based on a result of measurement of the light intensity by the light detection section 80. In particular, the light emitting state of the light emitting element 11 is measured by the light detection section 80 formed from a photodiode, and an output of the light detection section 80 is inputted to the light detection section control circuit 95. The light detection section control circuit 95 converts the output of the light detection section 80 into data or a signal representative of, for example, a luminance and a chromaticity of the light emitting element 11. The data is sent to the light source control circuit 93, by which it is compared with reference data, and a result of the comparison is sent to the two-dimensional image forming apparatus driving circuit 91. Then, upon next light emission of the same light emitting element 11, the numerical aperture or transmission factor of the pixel 31 is controlled based on the result of the comparison. In this manner, a feedback mechanism is formed from the elements mention. It is to be noted that control of the light emitting state of the light source 10 and control of the operation state of the two-dimensional image forming apparatus 30 may be carried out together. Further, the operation state of the spatial filter SF or Fourier transform image selection section 50 is controlled based on the result of the measurement of the light intensity by the light detection section 80. The correction of the luminance can be carried out by controlling the numerical aperture or light transmission factor of the aperture 51 of the spatial filter SF or Fourier transform image selection section 50.
An example wherein the three-dimensional image display apparatus described above with reference to
Meanwhile, an example wherein the light detection section 80 is attached to the two-dimensional image forming apparatus 30 is shown in
While the three-dimensional image display apparatus of the present invention is described above in connection with preferred working examples thereof, the present invention is not limited to the working examples. While, in the working examples, the collimator lens 12 is disposed between the light source 10 and the optical modulation section or two-dimensional image forming apparatus 30 or 30A, a microlens array wherein microlenses are arrayed in a two-dimensional matrix may be used instead.
The light source 10 may include a plurality of light emitting elements 11 arrayed in a two-dimensional matrix such that light beams are emitted in different light emitting directions from each other from each of the light emitting elements 11. By the arrangement, the light detection section or two-dimensional image forming apparatus can be illuminated with illuminating light beams successively emitted from different light emitting positions of the light source and having different light emitting directions from each other. A configuration of a three-dimensional image display apparatus where the light source having such a configuration as described above is adopted in the three-dimensional image display apparatus of the working example 1 is shown in
Or else, the light source may be configured such that it includes light advancing direction changing means for changing the advancing direction of the light beams emitted from the light emitting element. In particular, for example, a polygon mirror is rotated around an axis of rotation thereof while the inclination angle of the axis of rotation is controlled. Or, the light advancing direction changing means may be formed from a convex mirror having a curved face, a concave mirror having a curved face, a convex mirror formed from a polygon or a concave mirror formed from a polygon such that the position or the like of the mirror is controlled to vary or change the light emitting position of an illuminating light beam when it emerges from the mirror.
Or, the spatial filter SF or Fourier transform image selection section 50 may be replaced by a scattering diffraction restriction member having a number of apertures corresponding to the number of the light emitting positions and positioned on the rear side focal plane of the first lens L1. This scattering diffraction restriction member can be produced by forming apertures such as, for example, pinholes in a plate-like member which does not pass light therethrough. Here, the position of each of the apertures may be set to a position at which a desired Fourier transform image or diffraction light beam such as, for example, a Fourier transform image having the 0th diffraction order from among Fourier transform images or diffraction light beams obtained by the Fourier transform image selection section 50 or first lens is formed. Such positions of the apertures may correspond to the light emitting positions disposed discretely.
In the working examples 1 and 2, the optical modulation means or two-dimensional image forming apparatus 30 or 30A or the diffraction light production means is disposed on the front side focal plane of the lens which forms the Fourier transform image forming section 40, that is, the first lens L1, and the Fourier transform image selection section 50 is disposed on the rear side focal plane of the lens. However, as occasion demands, although deterioration appears with a stereoscopic image obtained finally, if such deterioration is permitted, then the optical modulation means or two-dimensional image forming apparatus 30 or 30A or the diffraction light production means may be disposed at a position displaced from the front side focal plane of the lens of the Fourier transform image forming section 40, that is, the first lens L1, or the spatial filter SF or Fourier transform image selection section 50 may be disposed at a position displaced from the rear side focal plane of the lens. Further, any of the first lens L1, second lens L2 and third lens L3 is not limited to a convex lens, but an appropriate lens may be selected suitably.
While it is assumed that, in the working examples 1 and 2, all light sources are single color light sources or light sources of a color proximate to a single color, the light source is not limited to that of this configuration. The light source 10 may emit light having a plurality of wavelength bands. However, in this instance, particularly where the three-dimensional image display apparatus of the working example 1 is taken as an example, preferably a narrow-band filter 71 for wavelength selection is disposed between the collimator lens 12 and the optical modulation means or two-dimensional image forming apparatus 30 as seen in
Or, the light source 10 may have a wide frequency band. In this instance, however, preferably a dichroic prism 72 and a narrow-band filter 71G for wavelength selection are disposed between the collimator lens 12 and the optical modulation section or two-dimensional image forming apparatus 30 as seen in
Or, it is possible to configure a light source for three three-dimensional image display apparatus for displaying three primary colors as shown in
Further, the modifications to the three-dimensional image display apparatus described above may include the light detection means described hereinabove in connection with the working example 3. Further, the temperature of the light emitting element may be monitored by means of a temperature sensor such that a result of the monitoring is fed back to the light source control circuit 93 so that luminance compensation or correction or temperature control of the light emitting elements is carried out. In particular, for example, a Peltier element may be attached to the light emitting elements to carry out temperature control of the light emitting elements.
While preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purpose only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-030567 | Feb 2007 | JP | national |
| 2007-169408 | Jun 2007 | JP | national |
