NL9401500A - Recording and reproduction system for threedimensional images - Google Patents

Abstract

The invention relates to a recording and reproduction system for three-dimensional images, for example for television, video or computer equipment. The invention is based on the measurement during recording and the control during reproduction of the spatial distribution of the light intensity or direction coefficient of each picture element or pixel in the image lines. The image will thus change for the viewer if the latter moves to a different viewing position. In order to achieve this, each pixel in the image lines, built up from a matrix of diode elements or a matrix of elements provided with liquid crystals, which sub- elements can be individually controlled and from which the light per sub-element is radiated or allowed to pass through in a different spatial direction. Each pixel may be provided with a lens for this purpose, the pixel sub-elements being positioned at the focal distance from this lens. As a result, depending on the position of the sub-element in the pixel, the light is radiated or allowed to pass through in virtually one direction only. In a corresponding manner, the light intensity originating from different spatial directions for each pixel sub-element is recorded in the camera, for example likewise with the aid of a lens for each pixel. The system is suitable both for recording and reproduction in black and white and for recording and reproduction in colour. A data reduction algorithm can be used to limit the bandwidth of the image signal. In a simplified embodiment of the recording and reproduction system, it is possible to record and reproduce the horizontal direction coefficient only, in which case cylindrical lenses may possibly be used for each pixel.

Description

Recording and playback system for three-dimensional images.

The invention relates to a recording and reproduction system for three-dimensional images, for example for the purpose of television, video or computer equipment.

In the past, attempts have been made several times to display three-dimensional images on a screen. The pictures were taken by recording images using a stereoscopic camera, which in reality consisted of two cameras placed at a close distance from each other and fixed relative to each other, with one camera having a green filter and the other camera a red filter was placed. A three-dimensional impression can be obtained by simultaneously viewing the two combined recordings via television, in which the viewer must wear special glasses with one red glass and one green glass.

The disadvantage of the system described above is that the images cannot be displayed in color and that the viewer must purchase and wear a special aid.

More recent developments with transparent liquid crystalline material, such as used in flat Liquid Crystal Display (LCD) screens, have led to a system in which the glasses consist of two LC glasses, which can be made transparent or opaque under the influence of an electrical signal. . The images are recorded stereoscopically in the same way as with the colored glasses. By alternately displaying the left image at high speed in synchronization, making the left lens transparent and the right lens opaque, and then displaying the right image, making the right lens transparent and the left lens opaque, a three-dimensional image impression is created.

The advantage of this method is that images can also be displayed in color, but here too special glasses are required, which must also be connected to the device via a cable or via optical or radio signals.

An additional drawback of both systems is that a stereoscopic image is displayed, which is the same from every viewing angle or direction of observation.

The object of the present invention is to provide a recording system and a screen, in which three-dimensional images can be displayed without using visual aids and in which the observed image, as with direct observation, depends on the direction of observation.

Unlike electron beam tubes CRTs, where the images are built up line by line with fluorescent material, the image is built up in flat LCD screens using discrete so-called pixels or pixels. For example, one line in the image consists of 800 pixels or pixels, all of which are controlled individually. The total image then contains, for example, 600 such lines and thus a total of 480,000 pixels. In color screens, each pixel consists of three smaller pixel areas, which emit red (R) green (G) and blue (B), respectively, which by mixing these basic colors can display almost the entire color palette perceivable to the human eye. One pixel or pixel provides uniform color information.

The principle of LCD screens, as used in computers or small TV sets, is based on the metered transmission of background light, for example generated by electro-luminance and filtered in the colors red, green or blue, by the respective pixel sections, depending on the electrical voltage across the liquid crystalline material. The polarization angle of the incident polarized light is increased or decreased depending on the voltage, so that this light is transmitted to a greater or lesser degree through a second polarized filter placed behind the liquid crystalline material. By making the liquid crystalline layer very thin, it is achieved that a relatively large opening angle or viewing angle of a maximum of approximately 90 degrees can be obtained. The spatial distribution of the light intensity per pixel, also known as the direction coefficient, is made as uniform as possible, so that the light output on all sides is approximately the same.

With very large screens built up of Light Emitting Diodes LEDs, we also strive to make the spatial distribution of the light intensity per pixel as even as possible.

The basic principle of the present invention is based on controlling and controlling the spatial distribution of the light intensity or the direction coefficient per pixel and will be described below with reference to a few figures.

By varying the direction coefficient per pixel and adapting it to the light intensity measured in the corresponding recording direction, a truly three-dimensional image is created, the image changing as one moves to a different viewing position.

A prerequisite for such a system is that the viewing angle or the horizontal as well as the vertical opening angle of both a camera and a screen must be recorded once for the entire three-dimensional recording and reproduction system. Here, the horizontal opening angle with respect to the vertical opening angle can for instance relate as the image ratio, or the ratio between the horizontal and the vertical image size. The consequence of this is that the so-called zoom function in the camera is not possible, because this would distort the three-dimensional image. In the three-dimensional image display according to the invention, this function can only be realized without image distortion, by actually moving the camera, whereby the horizontal and vertical opening angles are kept constant and are, for example, 90 and 67.5 degrees respectively.

The basic principle of the invention can be realized both in the form of an LED screen with light-emitting diodes, and in the form of a screen with liquid crystal crystal elements LCEs, because with these elements it is possible to realize the desired very small pixel sub-elements.

An implementation using electron beam tubes (CRTs) is only possible for very large screens, for example built from multiple CRTs, because the electron beams cannot be finely focused with current CRT technology.

To make full use of all the possibilities of three-dimensional image display, a larger screen with LED elements is preferable.

The image recording and display principle according to the present invention is of course also suitable for black and white image recording and display, but will be described in the more extensive form of color recording and display in the future.

Figure 1 schematically shows a pixel of a conventional display (1), composed of image lines (2) with pixels (3) each consisting of a red (R), a green (G) and a blue (B) segment with direction coefficients are approximately the same in all directions within the viewing angle.

Figure 2 schematically shows two pixels from an image line of a possible embodiment of a screen according to the invention, using light-emitting diode LEDs with a lens (5) per pixel (4) placed in front of it. Each pixel (4) is hereby reconstructed from a matrix formed by a large number of light emitting diode elements (6), arranged in horizontal and vertical rows. Figure 3 schematically shows how the diode elements (6), from which the pixel (4) is built up and which, for example, have a size of a few microns, emit their light via the lens (5) in different directions a per position of the diode elements, b and c.

Figure 4 shows how a possible embodiment of a screen according to the invention functions, in which use is made of liquid crystalline crystals. Each pixel (4) is, as in the embodiment with diodes, reconstructed from a matrix formed by a large number of transparent segments, arranged in horizontal and vertical rows, whereby the light transmission per pixel segment is directed in one specific direction together with the lens .

In the recording and reproducing system according to the invention, the term pixel is given a different definition, the smallest pixel that directs light in all directions within the | opening angle of the system, but with variable directivity for intensity.

Known systems for generating pseudo three-dimensional images are the systems of Travis (PCT) WO 90/07848 and Woodgate EP 0 570 179 A2. Both systems are equipped with light modulating elements on either side of the lens or the system of lenses, which necessitates very complex constructions. Both systems also provide a limited number of stereoscopic views in a limited number of directions.

First, the construction and operation of a possible embodiment of a screen according to the invention, which is built up with light-emitting diodes, will be described.

If the surface of a conventional light-emitting diode is considered, then the light emitted per unit area with an aperture angle of, for example, 90 degrees will be emitted in all directions, with a direction coefficient for the intensity increasing in the direction perpendicular on the radiating surface. Thus, an observer at any point in space within the aperture angle will perceive light from any point of the radiating surface of the light-emitting diode. By now placing a lens (5) in front of the light-emitting diode, in which the light-emitting surface of the diode is placed exactly at the focal length, that is to say in the focal plane, of this lens, it is achieved that almost all light emanating from one point of the light-emitting surface is emitted through the lens in only one direction.

This property is used in the screen according to the invention to be able to set the direction characteristic of a pixel, for the three-dimensional image, per direction for both the basic colors red (R), green (G) and blue (B). To achieve this, each pixel element (4), of which, for example, 800 are present per image line and, as indicated in Figure 2, is built up from a matrix of, for example, 128 x% diode elements, which can be individually controlled.

Depending on the position of this diode element, the light emitted by one of these diode elements will be emitted in only one discrete direction via the lens (5). Since the lens is about the same size as the pixel element, the beam emitted via the lens (5) is therefore also about the same size as the total pixel per diode element, and the light beam of an adjacent pixel will therefore substantially connect or overlap in the same direction.

The light intensity, as observed by an observer at any point within the aperture angle, will therefore be approximately the same even with the same current per diode surface, in other words the efficiency, with regard to the light output, hardly changes compared to a conventional LED screen. .

Figures 3 a, b and c indicate that the light from a diode element (6) is emitted through the lens (5) in only one direction, respectively. For this purpose, the distance between the diode elements, which together form a pixel, and the lens (5) must be equal to the focal length of the lens (5), so that these diode elements are in the focal plane of the lens. By spraying or pressing these lenses from a glass or plastic plate, whereby these lenses are formed in the said plate, the coherence between the lenses remains, whereby these lenses can have a rectangular shape, in order to increase the spatial light output, corresponding to the shape of a pixel. In order to fix the lenses precisely in position relative to the diode elements, the pixels, with their large number of diode elements, can be applied to the lens, or in a mount integrated with the lens.

The position of the diode elements may, of course, instead of exactly at the focal length, also be slightly further from the lens, such that the diode elements are displayed at a relatively great distance from the screen. However, it is important to achieve the widest possible opening angle per diode element. A system with multiple lenses is also possible in principle, but this is further disregarded in view of its complexity and the associated cost price.

The construction of the described LED screen is of course complex with regard to the number of picture elements to be controlled and the associated signal processing, but the constructional structure per element with one lens is relatively simple.

The control of the diode elements per pixel and per line can take place in the manner known for large stadium screens built with LED matrixes or LED video walls. Due to the discrete number of diode elements per pixel, the light per pixel is therefore also emitted in a discrete number of directions.

In order to limit the bandwidth of the video signal, it is possible to apply data reduction, for example by digitally describing the direction coefficients for the diode elements per pixel using polynomial planes and associated parameters of suitable order of magnitude. This is possible because an averaging effect occurs due to the closely spaced pixel elements, which together form the image, viewed from one specific direction of observation, so that less resolving power per pixel suffices. Per pixel, the polynomial areas, which indicate the direction coefficient, must then be converted into a diode current per diode element, which is maintained for the repetition time of one full period of the image frequency. To achieve this, the digital data processing for controlling the diode elements can be integrated in the screen.

In order to generate the colors red (R) green (G) and blue (B), pixel sections can be placed in the image lines, which radiate the corresponding color, as with conventional color screen displays. Each pixel part must be provided with its own lens to prevent an excessive dependence between color and direction. It is, however, better to have the diode elements in one pixel alternately radiate these colors, the position of these colors in the pixel being shifted one diode element at the adjacent pixels. In this way, a better color mixing is obtained and the three-dimensional image is less distorted. For the latter construction, however, the doping, which ensures the correct light color of the diode, must be applied on a micron scale.

In order to increase the amount of light entering the lens per diode element (¾), the respective light-emitting diode elements can be placed perpendicular to their respective optical axis through the lens, similar to the faces of a Fresnel lens.

In order to increase the production yield, also referred to as "yield", per screen, the screens can be built up of identical building blocks, which contain a manageable amount of pixels with the diode elements per building block and which, mounted next to each other, form a complete screen. These building blocks can be equipped with integrated lenses and integrated electronics for controlling the diode elements for the colors red (R) green (G) and blue (B). By applying the offered image signal for one of the directions of observation to all diode elements of one pixel in the image display, the three-dimensional image can be switched to a two-dimensional image. Likewise, a conventional two-dimensional TV or video image can also be displayed on the screen of the present invention. The display system can thus be made upwardly compatible with existing and any future TV and video standards. In this way it is even possible to simultaneously display different images in different directions on one screen.

The recording camera for the three-dimensional images consists of an inverse construction of the screen. That is, the light-absorbing cells in this camera may have the same construction as the pixel elements in the display, with the diodes replaced by photosensitive cells, such as, for example, photodiodes, phototransistors, or "Charge Coupled Devices" CCDs, with corresponding positions applied thereto. filtering for the colors red (R), green (G) and blue (B), so here too, lenses are placed per pixel element to determine the intensity for the different colors per incident direction, if a system of data reduction is used, for example as described above , the parameters of the polynomial areas per pixel are then determined immediately upon recording, which are then added to the image signal In order to be able to control the brightness for the recording, additional conventional optical means, such as, for example, additional lenses and apertures, can be added to the camera. applied.

A second possible embodiment of a screen according to the invention works with liquid crystalline crystals.

As with the embodiment with diodes, each pixel (4), of which there are, for example, 800 per image line, is built up from a matrix of, for example, 128 x 96 sub-elements (7,8), which can be controlled individually.

As with the version with LEDs, a lens is placed per pixel, where the center of the sub-elements is placed exactly at the focal length, i.e. in the focal plane, of the lens, or slightly behind it.

As shown in figure 4, these sub-elements consist of two foils with a layer of liquid crystalline material (9) in between, as used in LCD screens. On one side of this liquid crystalline material, horizontal transparent electrically conductive paths are formed, which form and connect the pixel part elements (7), and on the other side, identical vertical paths are formed, which form and connect the pixel part elements (8). This is done in the same way, but much smaller, as with a conventional LCD screen.

Figure 4 shows a cross section of one pixel part element (7,8). Between the plane in which the pixels with the sub-elements (7,8) are arranged and the light source (12), the light is polarized by a polarizing filter (10). Depending on the electrical voltage at the intersections of the guideways, which connect the pixel elements (7) and (8) of the different pixels, the polarization angle of the polarized light is rotated, so that this light is transmitted to a greater or lesser degree by polarizing filter (11), which is arranged on the side of the lens (13) between the lens and the plane of the pixel dividing elements (7) and (8).

In this way it is thus possible, depending on the position of the pixel element (7,8),> to control the directional coefficient for this position, so in total for a discrete number of directions, so that in the same manner as with the LED solution full three-dimensional image is created.

In order to generate the colors red (R) green (G) and blue (B), as with conventional color screens, pixel areas can also be placed here in the image lines, which let the corresponding color pass through a color filter, whereby each color portion of a pixel must also have its own lens.

As with the solution with LEDs, it is also better here to provide the sub-elements (7.8) per pixel alternately with color filters with the colors red (R) green (G) and blue (B), also here the position of these colors in the pixel, with the adjacent pixels one sub-element is shifted each time, in order to obtain a better color mixing.

In a simplified embodiment of the recording and reproducing system according to the invention, it is possible to record and display the images in a horizontal direction three-dimensionally, corresponding to the horizontal position of the human eyes, making them more difficult in vertical direction to observe. In the vertical direction, the matrix of subelements per pixel can for instance consist of three elements, which respectively represent the colors red (R) green (G) and blue (B), whereby the lens can be cylindrical per pixel instead of round. designed to deflect only in the horizontal direction and scatter in the vertical direction. In this simplified embodiment, therefore, only the directional coefficient of the light intensity per pixel in the horizontal direction is determined and reproduced.

Claims (17)

1. A recording and reproducing system for three-dimensional images in which, in accordance with the existing television and / or video systems, the images are recorded and reproduced, composed of image lines, which in turn are composed of pixels also called pixels, characterized in that that both in the recording and in the reproduction the direction coefficient of the recorded and reproduced light intensity per pixel for a given opening angle and for a discrete number of spatial directions in the recording is determined and reproduced in the reproduction. A three-dimensional image recording and reproducing system according to the preceding claim, characterized in that both the horizontal and vertical opening angles of both a camera and a display for the entire three-dimensional recording and reproducing system are recorded once, wherein the horizontal opening angle relative to the vertical opening angle can be, for example, as the image ratio, or the ratio between the horizontal and vertical image size. A three-dimensional image recording and reproducing system according to one or both of the preceding claim (s), characterized in that the directional coefficient of the recorded and reproduced light intensity, for adjacent pixel parts in an image line or for adjacent spatial directions within a pixel, The basic colors red (R), green (G) and blue (B) are alternately determined, so that the impression of a color image is perceived by color mixing during reproduction, and that, when these basic colors are chosen appropriately, almost the entire perceptible to the human eye. color palette covers. A recording and reproduction system for three-dimensional images according to one or more of the preceding claim (s), characterized in that the screen for displaying the images, per pixel in the image lines, is composed of a matrix of light-emitting diodes LEDs, the light of which is emitted by these LEDs depending on the electric current, within the horizontal and vertical opening angle defined for the total system, is emitted per diode element of a pixel in a different spatial direction. A recording and reproduction system for three-dimensional images according to one or more of claims 1 to 3, characterized in that the screen for displaying the images, per pixel in the image lines, is composed of a matrix of transparent electrically conductive elements separated by liquid crystalline material (LCEs), whereby the light transmitted through these LCEs, using voltage-dependent polarization rotation, within the horizontal and vertical aperture defined for the total system, per LCE sub-element of one pixel in another spatial direction is allowed. A recording and reproduction system for three-dimensional images according to one or more of the preceding claim (s), characterized in that in a screen the directionality between the direction in which the light is emitted or transmitted and the position of a sub-element of a pixel is obtained by arranging for this pixel and per pixel a lens, or a system of lenses, such that the sub-element, which emits or transmits the light, spreads on or in the vicinity of the focal length, i.e. in the focal plane, of these lens, or this system of lenses, whereby all the light coming from the relevant sub-element is emitted via the lens, or the system of lenses, in substantially the same spatial direction, so that for this direction the directional coefficient of the light intensity can be regulated in accordance with with the direction of the recorded image for this direction. A recording and display system for three-dimensional images according to one or more of the preceding claim (s), characterized in that the camera for recording the images, per pixel in the image lines, is composed of a matrix of photosensitive elements, for example consisting of photodiodes, phototransistors, or so-called "Charge Coupled Devices" CCDs, whereby the light intensity, within the horizontal and vertical opening angle defined for the total system, is determined per sub-element of a pixel for light coming from a different spatial direction . A three-dimensional image recording and reproducing system according to the preceding claim, characterized in that, in a camera, the directionality between the direction from which the light is absorbed and the position of a sub-element of a pixel is obtained by for this pixel and for each pixel a lens, or a system of lenses, to be arranged such that the sub-element, which absorbs the light, is located at, or in the vicinity of, the focal length, i.e. in the focal plane, of this lens, or this system of lenses, through which all the light absorbed by the respective sub-element via the lens, or the system of lenses, is taken from substantially the same spatial direction, so that the direction coefficient of light intensity can be measured for this direction. A recording and display system for three-dimensional images according to one or more of the preceding claim (s), characterized in that the lenses arranged in front of the pixels, or a part of the pixels, are applied, for example, by spraying or pressing formed from a single sheet of glass or plastic, the interconnection of which remains at the interfaces between these lenses. A recording and reproduction system for three-dimensional images according to one or more of the preceding claim (s), characterized in that the sub-elements which together form one or more pixel (s) are integrally integrated with the front lens or lenses arranged in the relevant pixel (s), in order to achieve a good guarantee of the position of these target elements relative to the lens or lenses. A recording and reproduction system for three-dimensional images according to one or more of the preceding claim (s), characterized in that in order to improve the manufacturability and to reduce the loss of production, for the cameras and / or the screens building elements are made that each separately consist of a group of pixels with the associated lenses, any color filters and the electronics needed to process the signals for this group of pixels, whereby these building blocks can be seamlessly combined into a larger whole. A recording and reproducing system for three-dimensional images according to one or more of the preceding claim (s), characterized in that, using this system, conventional two-dimensional images can also be reproduced by applying to all sub-elements of a pixel intended for the same color, to offer the same signal, for example equal to the three-dimensional image signal intended for one of these sub-elements of a pixel for the relevant color, or equal to a conventional television or video pixel signal of the relevant color, so that the system upwardly compatible with existing television or video systems. A three-dimensional image recording and reproducing system according to one or more of the preceding claim (s), characterized in that data reduction is applied to limit the bandwidth of the image signal, for example, the approximate direction coefficient for the intensity of the pixel sub-elements are determined and recorded by means of the parameters of polynomial planes of suitable order size and wherein for the image display, these direction coefficients per pixel sub-element are calculated from the parameters of these polynomial planes. A three-dimensional image recording and reproducing system according to one or more of the preceding claim (s), characterized in that, in order to simplify the system and in accordance with the horizontal position of human eyes, the directivity of the light intensity per pixel is determined only in the horizontal direction in the recording and / or reproduced in the reproduction, the direction coefficient being substantially constant in the vertical direction for the pixel in question. A three-dimensional image recording and reproducing system according to the preceding claim, characterized in that the recorded and reproduced light intensity, in vertical direction per sub-element of a pixel, is determined adjacent for the basic colors red (R) green (G) and blue (B), so that, by color mixing in the display, in a vertical direction per sub-element, or per vertical group of sub-elements, a pixel's impression of one color is observed. A three-dimensional image recording and reproducing system according to one or both of the preceding claim (s), characterized in that the directionality between the horizontal direction in which the light is received, radiated or transmitted and the horizontal position of a sub-element whether a vertical group of sub-elements of a pixel is obtained, by arranging for this pixel and per pixel a cylindrical lens, or a system of cylindrical lenses, such that the sub-element, or the vertical group of sub-elements, with which the light is received , emitted or transmitted, at or near the focal length, that is to say in the focal plane, of this cylindrical lens, or this system of cylindrical lenses, through which all the light emanating from the respective sub-element, or the respective vertical group of sub-elements, through the cylindrical lens, or the array of cylindrical lenses, in or from substantially the same horizontal spatial direction is recorded or broadcast, so that for this horizontal direction, the light intensity directional coefficient can be measured or controlled in accordance with the horizontal directional coefficient of the recorded image for this horizontal direction. A three-dimensional image recording and reproducing system according to one or more of claims 14 to 16, characterized in that data reduction is used to limit the bandwidth of the image signal, for example approximately the horizontal Direction coefficient for the intensity of the pixel sub-elements is determined and recorded by means of the parameters of a polynomial of an appropriate order, and for the image display these horizontal direction coefficients per pixel sub-element, or vertical group of pixel sub-elements, are calculated from the parameters of this polynomial.