GB2111798A - Television colour stereo system - Google Patents

Abstract

At least two television cameras 1, 2 view an object (not shown) so as to produce image signals reproducing an image on the viewing screen of a receiver 6 when the image signals are received by the receiver 6. The reproduced image may be viewed through polarized glasses 10 and the system includes a coder 3, 4 coupled to the output of each camera 1, 2 for alternately selecting the image signals according to a prearranged pattern. The television cameras 1, 2 have respective optical axes spaced apart by an eye-separation distance, so as to function as a stereoscopic camera unit when viewing the object. Two oppositely polarized light- filter groups 7, 7' may be positioned on the viewing screen in successive regions corresponding to the prearranged pattern, so that the image is perceived stereoscopically when the polarized glasses 10 are polarized in a manner corresponding to the polarization of the filter groups 7, 7'. <IMAGE>

Description

SPECIFICATION Television colour stereo system The invention relates to a colour stereo system, which permits the transmission and reception of stereoscopic images.

Colour television systems of the prior art do not permit the transmission and reception of colour stereoscopic images without extensive modification of the colour television transmitter and of the colour television receiver.

It is an object of the invention to devise a colour stereo television system requiring a minimal amount of retrofit of existing television equipment, so that an existing colour television receiver can be used for viewing a stereoscopic picture without any need to modify the electronics of the available colourtelevi- sion receiver.

With this object in view, the present invention provides a colour stereo television system including at least two television cameras for viewing an object so as to produce image signals reproducing an image on the viewing screen of a receiver when the image signals are received by the receiver, and wherein the reproduced image may be viewed through polarized glasses, comprising in combination; coding means coupled to the output of said cameras for alternatively selecting the image signals according to a prearranged pattern, the television cameras having respective optical axes spaced apart by an eye-separation distance so as to function as a stereoscopic camera unit when viewing the object, and two oppositely polarized light-filter groups positionable on the viewing screen in successive regions according to a preselected pattern corresponding to said prearranged pattern, whereby, the image is perceived stereoscopically when the polarized glasses are polarized in a manner corresponding to the polarization of said filter groups.

In other words, this object is attained by the use of a coder adapted to alternately select image signals, according to a prearranged pattern, of two television cameras viewing an object. The television cameras have respective optical axes spaced apart by an eye separation distance of about 6.5 cm, so as to function as a stereoscopic camera unit when viewing the image. The image signals are received in a receiver provided with a viewing screen for reproducing the image, and two oppositely polarized light filter groups are positioned on the viewing screen in successive regions according to a preselected pattern corresponding to the prearranged pattern; thus when the screen is viewed through two similarly polarized glasses, the image is perceived stereoscopically.Thus a viewer will see with his left eye only the correspondingly polarized left image, and will see with his right eye only the oppositely polarized right image, consequently obtaining a complete sterescopic view.

The only required modification of a conventional colour television receiver is the addition of two oppositely polarized light filters to the image screen, which are alternately distributed on the image screen in certain individual zones, and where the distribution and timing or succession pattern of the individual zones of the polarizing filters corresponds to the location and timing or succession pattern of switching of the left and right TV cameras at the transmission end of the system.

In a further development of the invention the polarization filters are dimensioned to correspond to the size of each image picture point or pixel, and their direction of polarization changes from pixel to pixel. A receiver of this type reproduces stereoscopic colour transmissions in an alternating picture sequence point by point. As the cathode ray impinges on the viewing screen point by point, corresponding filter elements along the screen have respective successive changes in their direction of polarization.

When switching the polarization of the transmitted image as a function of the lines transmitted, in one version of the invention polarized filter strips are used, which have a width corresponding to the width of a pair of adjacent lines, and wherein the direction of the linear polarization changes from one pair of lines to another pair of lines.

If one conceives all lines of a screen to be consecutively numbered from the top to the bottom, or vice-versa, then in a conventional TV system, first the even lines, and subsequently the odd lines are reproduced. It is consequently possible to impart to a pair of immediately adjacent lines on the screen the same direction of polarization, and to impart to the succeeding pair of adjacent lines on the screen a direction of polarization opposite to the direction of polarization of the previous pair of lines. Thus, two location-wise adjacent lines on the screen will be seen to have the same direction of polarization imparted thereto. Thus, if the transmitting TV cameras are switched in a similar manner, there will be reproduced in a corresponding sequence images on the screen which a viewer perceives through his polarized glasses alternately as a left picture and as a right picture.

If a pair of an odd line and a location-wise adjacent even line is considered as providing information with respect to a "complete" line, from a point of view of conveying complete image information, then the above-noted sequence of polarization varies from one "complete" line to the next "complete" line, and the polarized transmission can therefore be denoted as an alternating "complete line" to "complete line" change.

In a further advantageous implementation of the invention, the direction of polarization of adjacent filter strips varies from line to line in a television field, where two television fields constitute a complete television frame. If the sequence of transmitted lines is such that first odd lines are transmitted during the first field, and subsequently even lines are transmitted during the second field, then in this version of the invention an image corresponding to that viewed by the left eye of an observer is transmitted first during the first field of a frame, leaving alternate lines blank, followed bytransmission of an image viewed bythe right eye, filling in the previously blank lines.The first series of, for example, odd lines, is then viewed through a correspondingly polarized filter strip by the left eye, while the second series of, for example, even lines is viewed through an oppositely polarized filter strip by the right eye of the observer. Thus the left and right images are interlaced or interspersed with one another from line to line, as is their corresponding polarization. This mode corresponds to a line-by-line change of the polarization. Depending on the connotation used, the term "line" used hereinbefore is sometimes referred to as "half-line", and the term "complete line" referred to hereinbefore, is sometimes denoted as a "line". In what follows, however, the term "line" will be defined as a line of one of two interlaced fields, unless specifically referred to otherwise, where two fields constitute the complete television frame.

The invention will be described further, by way of example, with reference to the accompanying drawings, wherein similar reference characters denote similar elements throughout the several views and in which: Figure 1 is a schematic block diagram of a colour stereo television system, according to the present invention; Figure 2 is a partial cross-section through a receiver screen showing the polarized light-filter groups positioned on the screen; Figure 3 is a fragmentary cross-section of the screen of Figure 2 in perspective, illustrating the structure of the polarized light filters when the light filter has the size of a pixel; Figure 4 is a schematic diagram illustrating the position of the polarized light filters when the light filter of each group is dimensioned to correspond to the length and width of a pair of two adjacent lines on the screen; and Figure 5 is a block schematic diagram illustrating the position of the light filters when the light filter of each group is dimensioned to correspond to the length and width of a single line.

Referring now the drawings, and in particular to Figure 1, image signals produced by the television cameras 1 and 2, when viewing a non-illustrated object, are first passed from the output of the cameras to coding means, such as colour coders 3 and 4, which select the image signals alternately and intermittently according to a prearranged pattern; the image signals are transmitted by means of a non-illustrated transmitter to the colour television receiver 6. On the screen 6 of the colour television receiver 6 there is shown a large-scale distribution of two polarized light-filters 7 and 7'.A left glass 9 of viewer-glasses 10 is polarized in the same sense as the polarized light-filter 7, and the right glass 8 of the viewer glasses 10 is polarized in a sense opposite to that of the left glass 9, and corresponds to the polarization of the polarized light filter 7'. A viewer therefore perceives with the aid of the glasses 10 with each eye a different image corresponding to the images seen by the television cameras 1 and 2, respectively, which are fused by the brain of the viewer into a single stereoscopic image.

As seen in Figure 2, which is a fragmentary cross-section of the screen 11 in plan view, there will be seen the polarized light-filters 12 and 13, each having the size of an individual image point or pixel; the reproduced image includes a multiplicity of such individual image points or pixels. The screen 11 includes the conventional colour layer 14, and the conventional aperture mask 15.

It is a precondition for the versions described, which use alternately opposite polarized light-filter groups in respective zones, that the conventional transmission technique be utilized, in which first odd-numbered lines and then even-numbered lines are transmitted.

As can be seen from Figure 3, each image point or pixel consists of phosphorescent image points RGB for the colours red, green and blue, respectively, and wherein each image point or pixel is associated with respectively oppositely polarized filters 16 and 17 in an alternating sequence. As dense a layering as possible of the screen with such image points or pixels is obtained by way of an illustrative example only by the arrangement illustrated in Figure 3.The respective phosphorescent points RGB connected by a dotted triangle form an image point or pixel on the screen, and are perceived by a viewer viewing the screen through glasses 10 as a simultaneous rendition of a steroscopic colour TV image, when the colour coders at the transmitter are switched in the same sequence point by point, corresponding to the distribution of the alternating sequence of the polarized light filters on the viewing screen.

The phosphorescent points of the individual pixels 16 or may be implemented not only in the circular form shown in Figure 3, but may alternately be implemented also in the shape of a slit (in-line system) or in line form (trinitron system).

In lieu of the system shown in Figure 3, the light-polarized filters 18 and 19 can extend in an alternate version of the invention along two adjacent lines on the screen, namely the light filter of each group is dimensioned so as to correspond to the length and width of a pair of two adjacent lines, and wherein the filter of one group alternates along the screen with the filter of the other group from one pair of lines to another pair of lines. By this manner of distribution and positioning of the polarized filters, the received image is alternately polarized along successive pairs of lines or successive "complete" single lines, if the alternate definition of a "complete line" is employed, where a complete line consists of first and second geometrically adjacent lines of two consecutive fields in a single frame of a television image. Thus in Figure 4 the line 3 has a direction of polarization opposite to that of the line 1.

Line 5 is again polarized in a direction opposite to that of line 3, and soon. A viewer who uses glasses 10 with coherent polarization therefore perceives a stereoscopic image, whose individual "complete" lines, as successively reproduced on the viewing screen 11, are respectively oppositely polarized; the image thus alternately contains a line of the left image (television camera 1) and of the right image (television camera 2). Aviewertherefore sees during the first field of a frame, with odd lines being scanned alternately, lines of the left and right image through the glasses 10, which are fused by the viewer's brain into a stereoscopic image, and sees during the second field of the frame being scanned the even lines, where the lines of the right image and of the left image are alternately reproduced on the screen.As the transmission sequence is not impaired by the arrangement of the filters, according to the invention, the resolution of the image is not impaired either.

Finally, Figure 5 shows an arrangement of polarization filters 20 and 21 wherein each light filter is dimensioned to correspond to the length and width of an individual line of a field. Taking into account that the television transmission image scans alternate lines of an object during the first field, corresponding, for example, to the odd-numbered lines according to Figure 5, at first the odd-numbered lines of the first field (or one half of the interlaced image) are reproduced and viewed through the polarized filter 20 through the left glass 9 of the glasses 10; subsequently the even-numbered lines are viewed and reproduced through the polarized filter 21 through the right glass 8 of the glasses 10, corresponding to the second field of a frame (or the second half of the interlaced image). The viewer therefore perceives a stereoscopic image in which the polarization changes from field to field.

It is a further essential advantage of a colour stereo receiver equipped with the polarized light filters according to the present invention, that the receiver is fully compatible for reproducing the still conventional two-dimensional images currently used, as the polarization filters positioned on the screen, when viewed by a viewer without the polarized glasses 10 do not, for all intents and purposes, affect the quality of the two-dimensional image viewed.

While only several embodiments of the present invention have been shown and described, it is obvious that many changes and modifications may be thereunto without departing from the scope of the invention.

Claims (6)

1. A colour stereo television system including at least two television cameras for viewing an object so as to produce image signals reproducing an image on the viewing screen of a receiver when the image signals are received by the receiver, and wherein the reproduced image may be viewed through polarized glasses, comprising in combination; coding means coupled to the output of said cameras for alternately selecting the image signals according to a prearranged pattern, the television cameras having respective optical axes spaced apart by an eyeseparation distance so as to function as a stereoscopic camera unit when viewing the object, and two oppositely polarized light-filter groups positionable on the viewing screen in successive regions according to a preselected pattern corresponding to said prearranged pattern, whereby, the image is perceived stereoscopicallywhen the polarized glasses are polarized in a manner corresponding to the polarization of said filter groups.

2. A colour stereo television system as claimed in claim 1, wherein the reproduced image includes a multiplicity of pixels, each having a predetermined size, and wherein the light-filter of each group is dimensioned to correspond to the size of each pixel, a filter of one group alternating along said screen with a filter of the other group from one pixel to another pixel.

3. A colour stereo television system as claimed in claim 1, wherein the reproduced image includes of a multiplicity of lines, each having a predetermined length and width, and wherein the light filter of each group is dimensioned so as to correspond to the length and width of each of said lines, a filter of one group alternating along said screen with a filter of the other group from one line to another line.

4. A colour stereo television system as claimed in claim 1, wherein the reproduced image includes a multiplicity of lines, each having a predetermined length and width, and wherein the light filter of each group is dimensioned so as to correspond to the length and width of a pair of two successive lines, a filter of one group alternating along said screen with a filter of the other group from one pair of lines to another pair of lines.

5. A colour stereo television system as claimed in any preceding claim wherein the eye-separation distance is about 6.5 cm.

6. A colour stereo television system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.