CA2176574A1 - Colour autostereoscopic display - Google Patents
Colour autostereoscopic displayInfo
- Publication number
- CA2176574A1 CA2176574A1 CA002176574A CA2176574A CA2176574A1 CA 2176574 A1 CA2176574 A1 CA 2176574A1 CA 002176574 A CA002176574 A CA 002176574A CA 2176574 A CA2176574 A CA 2176574A CA 2176574 A1 CA2176574 A1 CA 2176574A1
- Authority
- CA
- Canada
- Prior art keywords
- image source
- display according
- colour
- image
- display
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
- H04N13/30—Image reproducers
- H04N13/302—Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays
- H04N13/31—Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays using parallax barriers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
- H04N13/30—Image reproducers
- H04N13/302—Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays
- H04N13/305—Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays using lenticular lenses, e.g. arrangements of cylindrical lenses
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
- H04N13/30—Image reproducers
- H04N13/302—Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays
- H04N13/32—Image reproducers for viewing without the aid of special glasses, i.e. using autostereoscopic displays using arrays of controllable light sources; using moving apertures or moving light sources
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
- H04N13/30—Image reproducers
- H04N13/324—Colour aspects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
- H04N13/10—Processing, recording or transmission of stereoscopic or multi-view image signals
- H04N13/194—Transmission of image signals
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
- H04N13/20—Image signal generators
- H04N13/204—Image signal generators using stereoscopic image cameras
- H04N13/239—Image signal generators using stereoscopic image cameras using two 2D image sensors having a relative position equal to or related to the interocular distance
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
- H04N13/20—Image signal generators
- H04N13/204—Image signal generators using stereoscopic image cameras
- H04N13/243—Image signal generators using stereoscopic image cameras using three or more 2D image sensors
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
- H04N13/30—Image reproducers
- H04N13/398—Synchronisation thereof; Control thereof
Abstract
A polychromatic three dimensional display comprises a first (5) and second (8) image sources, the second image source (8) adapted to reduce selectively the field of view of the first image source to provide thereby a time multiplexed three dimensional autostereoscopic image. The display also comprises a switching colour filter (12) disposed adjacent to the second image source which comprises a plurality of regions each switchable between different colours to enable colour modulation of the generated image.
Description
~0 95/14353 2 1 7 6 5 7 ~ r~
COLOUR AUTOSTEREOSCOpIC l7ISpr 2,y The present invention relates to three dimensional ' autostereoscopic displays. Such autostereoscopic displays 5 can be made from a high frame rate two dimensional display and a device which makes the picture on the two dir-n~:ion~
display visible from different directions.
To display an autostereoscopic three dimensional image, a series of views of the object to be imaged are lO required. These might be captured by, for example, surrounding a solid object with an array of conventional cameras .
With such systems, each view in the series is put up on the two dimensional display in turn and made visible lS from a particular general direction. If the series is repeated quickly enough that the human eye perceives no flicker, the apparent effect is a display whose image content will depend on from where the human eye looks. By appropriate matching of view to direction of viewability, 20 it is possible to recreate the three dimensional image on the display.
one way of making such a display is to use a cathode ray tube as the two dimensional display, and a lens and a shutter as the device which limits the field of view of the 25 picture on the display.
The lens forms a virtual image of the cathode ray tube. The shutter, which reduces the field of view of the image, is positioned adjacent to the lens.
If the position of the aperture in the shutter can be 30 changed rapidly, the angle from which the image can be seen may be varied as different pictures are presented in turn for display on the CRT screen. Each picture can be the view of some scene taken from a chosen viewpoint. So long as the picture for each direction is repeated sufficiently 35 frequently, typically at least 50 Hz, and the shutter is stepped in sequence with the view on the CRT display, then different views will be seen from different positions and _ _ _ _ _ . . . . . .
W095/14353 21 7657~ r~ A?~
a three dimensional im;-ge will be observed. There ~re several alternative optical and image forming arrangements that are operationally equivalent to the description given above. Implementations can consist of 2 dimensional image 5 forming devices made from an LCD or from a CRT. The shutter can be made from an LCD. The arrangement can place the shutter between the image f orming device and the observer or can position the image forming device between the shutter and the observer. The light can be collimated 10 or non-collimated. In a presently preferred implementation, the image forming device is a CRT and a viewing lens i5 added between the viewer and the shutter to narrow the pencils of rays passing through the aperture into near-parallel beams.
A number of devices for producing a colour 3D display employing the above principles have been proposed. One such way of making a colour three dimensional display is to have a colour CRT. However conventional colour CRT's are not bright because they incorporate shadow masks. Since the 20 shuttering system absorbs a lot of light the CRT in this system needs to be bright, requiring a great deal of power, and brighter than available by current masking techniques.
Another way of making a colour three dimensional display is to use dichroic mirrors to combine the images 25 from one red, one green and one blue CRT. The problem is that, at least in current three dimensional displays, the imaging lens is large, and there is little space for dichroic mirrors. Furthermore, it becomes ne~ Ary to register the CRTs so that the position of each pixel is the 30 same on each CRT. The whole system is bulky, heavy and expensive because three times as many I - t_s are needed .
The bulk and expense of three CRT's can be avoided by using one C~T with a white phosphor, then f iltering the 35 emitted light so that rays of each of the primary colours are transmitted in turn. The disadvantages of this approach are that the CRT needs to operate three times f aster than ~W095/14353 - ~1 76574 f~ 51.'0~'t~
otherwise, it needs to be ~righter than otherwise, and a f ilter which can switch between the primary colours is required .
A f ilter which switches between the primary colours S has been made for a colour two dimensional display. It might seem that the obvious way to make a colour three dimensional display would be to place this filter over the front of the three dimensional display. Colour images miqht be produced on a black/white three dimensional display 10 by placing a f ilter against the front which switches through the primary colours. The problem is that the liyuid crystal of which present switching colour filters are made cannot switch yuickly enough.
When the f ilter is used on a two dimensional display 15 the CRT displays the three primary colour ~ ntS of the picture one by one. Ideally the filter should change colour in the time interval between the end of the display of one primary colour and the beginning of the display of the next. This time interval is short and even on the two 20 dimensional display the filter is not fast enough for this purpose .
In fact the filter is divided into horizontal bands which can be switched i nrl~r-n~l-ntly. The idea is that as the CRT electron beam writes each picture from the top of 25 the screen to the bottom, the horizontal bands of the filter are also switched one by one, from top to bottom.
Provided each band begins switching immediately after lines adjacent to it have decayed, there is sufficient time to complete switching before the adjacent lines are written 30 with new information.
This solution works for the two dimensional display, but the frame rate of the CRT in the three dimensional display is much higher. There is therefore less time before each line is rewritten, and this time is insufficient for 3 5 the f ilter to switch .
An alternative to using a switching colour filter would be to make a wheel comprising a red, ~-reen and blue _ _ _ _ . _ _ . . . _ . . _ _ . . .
W095/14353 - 2 l 76574 P~ r~
filter and spin this in ~ront of the screen. This might work with a two dimensional display because the wheel need only spin at 60 Hz. With a three dimensional display with 8 views, for example, the wheel would have to spin at 480 5 Hz, this would be impractical.
The presently available switching colour filters are slow because they are based on slow-switching liquid crystals. The liquid crystals in the shutter used in the three d;r^~ AnAl display switch much more quickly. It has 10 been suggested that it might be possible to conf igure the shutter to switch each slit through each of the primary colours in turn before closing that slit and opening the next. Colour images might be produced on a black/white three dimensional display by making the shutter f ilter the 15 primary colours in turn while each slit is open.
Unfortunately, shutters which work in this way are not available at present.
It is useful to consider if a pair of spinning wheels could be conf igured to behave like a colour-switching 20 shutter. Such a system is ~l; cc~lcsed in ' Wireless World, Feb 1942-Stereoscopic colour TV~ . In a system with a wheel with a slit spinning so as to scan the slit in the focal plane of the collimating lens, with a colour wheel placed adjacent to this slit, the colour wheel spinning at a 25 higher rate so that at each slit position light is filtered to produce each of the primary colours.
The problem with this proposed system is that the shutter slit does not move from position to position, but is always moving. So the slit will be at a slightly 30 different position as each of the colour filters passes it.
This will produce a registration problem, there will be positions at which an eye will see, for example, the red ~ AAt of one view superposed on the blue and green components of a different view. This would be quite 35 unsatisfactory.
According to the present invention there is provided a polychromatic three dimensional display comprising:
-~095114353 ~1 76574 P~,l,. ~A`7~48 a f irst image source;
a second image source, the second image source being adapted to reduce selectively the f ield of view of the - f irst image source to generate thereby a time multiplexed 5 three ~l;r -irn~l autostereoscopic image; and a switching colour filter ~i.cposr~ adjacent to the second image source and comprising a plurality of regions each switchable between different colours to enable colour modulation of the generated image.
Preferably the first image source is a spatial light modulator, and the second image source is a Sr~nn;ng light source which selectively illuminates the first image source from one of a plurality of positions. Alternatively, the f irst image source is a monochrome or white rhn5rhnr 15 cathode ray tube or similar device, and the second image source is a shutter comprising a plurality of in-lr~ronr~r~ntly activated apertures.
Preferably, there is also provided an imaging lens positioned between the two image sources. The imaging lens 20 may be either single or multi-element, and allows greater optical design freedom, together with the possibility of producing large images from ~ .^nts of reduced size.
A collimating lens may also be provided to provide a viewer with collimated light to improve the 25 autostt~ oscu~ic effect of the display.
The filter may include a rotatable disc comprising a plurality of differently coloured regions, but is preferably comprises a plurality of regions that are individually switchable between a plurality of colours.
30 With this latter arrangement, for displays where the second image source is a shutter, there may also be provided control means for controlling the activation of the switching colour filter strips and shutter ape~ Lu ~s so that each strip starts switching to the next colour 35 immediately after the termination of the view which passes light through that strip.
WO 95114353 , 2 1 7 5 5 7 4 , "~
Pre~erably the colour f ilter has portions ~orL~lu~ lin~ the three primary colours.
One example of the present invention will now be described with reference to the a-_ -nying drawings in 5 which:
Fig. 1 is a schematic diagram showing the basic principles of an autostereoscopic three dimensional display;
Fig. 2 is a diagram showing a prior art example of a 10 monochrome autostereoscopic three dimensional display;
Fig. 3 is a colour adaptation of the display of figure 2;
Fig. 4 is a prior art polychromatic autoste~eos~u~ic three dimensional display employing a spinning disc;
lS Fig . 5 is a schematic diagram of a f irst example autostereoscopic poly.~ ""atic three dimensional display according to the present invention;
Fig. 6 is a schematic diagram of a second example autostereoscopic polychromatic three dimensional display 20 according to the present invention; and Fig. 7 is a schematic diagram of a third example autostereoscopic polychromatic three dimensional display according to the present invention.
Figure 1 shows the basic concept of a known three 25 dimensional display. Pictures of an object are formed by cameras 3 ranged round the object 2 and pointing at it from different directions. One picture at a time is reproduced on the display 1. The display 1 can conf ine the direction f rom which this picture is visible . It does this so that 30 the direction of visibility matches the direction of the camera from which the picture is received. Other pictures are shown from other cameras 3 in a similar manner. Once a picture from each of the cameras 3 has been shown, the sequence is repeated. The rate of repetition is such that 35 the display of each picture to each direction will appear continuous to an observer 4 inspecting the display from different angles.
Wo 951143S3 ~ 1 7 6 5 7 4 p~
Whenever collimated light i 1 l1~nin7~tes the observer 4, he will see the picture on the display. However each of the observer's eyes will be illuminated by collimated light travelling in different directions. So each eye will see a different picture. The three dimensional image displayed will therefore be of the type described with reference to f igure l .
In the prior art system of f igure 2, a cathode ray tube (CRT) 5 is used as an image source. Light from the image source 5 passes through an imaging lens 6 and an aperture 7 in a shutter 8. The shutter 8 comprises an array of i ~ op~n~lP~ltly activated apertures 7 . The light then passes through a collimating lens g to be viewed by an observer. A different aperture 7 is opened for each of the images that are displayed on the image source 5, so that a viewer perceives each of the images to be from a source of a different position and a monochrome three dimensional display is produced.
Figure 3 shows the monochrome three dimensional display of figure 2 adapted to be used a colour three dimensional display by the additional of a colour filter lO. The colour filter lO switches between the three primary colours in turn, and the sequence of images displayed in the image source 5 is repeated three times, once for each of the primary colours. As mentioned above, such a system has the serious problem that a switching times of the image source 5, shutter 8 and particularly the colour filter lO must be very small so that no flicker is observed by the viewer.
In the prior art system of figure 4, the moving slit shutter 8 is provided by a spinning disc, and the colour is produced by the rotation of a spinning disc ll that is divided into three portions, each of the portions being coloured according to one of the three primary colours. In this example, the filter disc ll is spun at high speed to produce three 5~1rpO5c~7 ] y identical images in the three primary colours, which are perceived by an observer to be Wo95/14353 2 1 76574 a single image of combined colour. Unfortunately, as the slit 7 is continuously moving, the three coloured images will be perceived to be coming from slightly different positions, so that they will not overlap perfectly and a 5 full three dimensional effect will not be produced.
In the first example of the present invention shown in Fig . 5, the display has a f irst image source 5, which is a spatial light modulator provided by a liquid crystal display or similar device. The device also includes a 10 scAnnin~ light source 8 and spinning disk filter 12. There is also provided an imaging lens 6, which is not essential, but which provides greater c~nronont design freedom. In operation the f irst image source 5 displays a series of images of an object from different viewpoints, and, for 15 each image displayed, a different portion of the light source is activated, illuminating the image from one direction and malcing it appear to come from a different position. As with the prior art examples, with each of the images being produced at a rate at which the eye perceives 20 no flicker, an autostereoscopic display is produced.
However, as there is provided a colour filter 12 between the light source 8 and image source 5, a series of colQur modulated images will be presented to a viewer. The colour f ilter 12 must spin at a speed which ensures that the 25 illuminating light is modulated to the correct colour for the image being presented, but as only one of the light sources 8 is activated at any one instant, the rotation of the colour filter 12 can follow the activation of the individual light sources 8, providing a complete series of 30 images for a first colour, and enabling the filter 12 to have rotated to the next colour by the time that each of the sources 8 has been activated. This greatly reduces the n,~C-~cc:Ary spinning speed for the filter.
Fig. 6 shows a second example of the present invention 35 which employs very similar principles to that of the first example, but which, in place of the spinning colour filter 12 has a colour f ilter comprising a plurality of _ _ _ _ _ _ _ _ .. _ . ... _ .. .... . .. . . ... .
WO951143~3 ~ ~ 76~7~ P~ r~48 individually switchable regions 13. Each of these regions 13 can be switched between one of a number of colours, in this example red, green and blue An example of a device with such characteristics is a NU 700S colour shutter from 5 Tectronix Ltd. In this example, the light source 8 and image source 5 operate in a similar fashion to that of the first example, but the filter is aligned with the individual light sources. In operation, each of the regions 13 of the filter 12 is activated to change colour 10 immediately after its ~ u, Le:,~onding light source has been de-activated, so that the time period in which each region must change to the next required colour is r-~;mised. This enables the employment of a filter with a reduced switching speed for each of its regions.
In the example of the present invention shown in f igure 7, a f irst image source 5, imaging lens 6, shutter 8 and collimating lens 9 are provided, in addition, a switching colour f ilter 12 is also provided . The imaging lens 6 and collimating lens 9 are not essential to the invention, but, as mentioned above, enable greater design freedom and components of reduced size to be employed. The switching colour filter 12 is positioned between the imaging lens 6 and the shutter 8 and, as with the second example, comprises an array of individually switchable regions 13, each of the regions being able to be switched between the primary colours. This example may, alternatively, employ a spinning disc filter of the type described with ref erence to f igure 5, in place of the switchable strip colour filter 12.
As previûusly mentioned, spinning disc colour filterS
would normally have to be spun at great speed to be employed in an autostereoscopic display, but, with the examples of the present invention which employ such filters, this speed is greatly reduced by the employment of only a fraction of one of the coloured apertures in colour modulation at a particular instant. Also, as previously mentioned, the switching time of switchable colour filters _ _ _ _ . . .. . .. _ ... .... . _ _ _ _ . _ _ . _ is slow, but in the two examples of the present invention which employ such filters, this is overcome by individually switchable strips 13, which can be activated prior to their corresponding aperture 7 being opened in front of them. As 5 each of the strips is only visible for a short period of time, a larger switching time is available for activating them and changing their colour. Different speed of switching colour and aperture can be exploited to give the combined effect on the two at the speed of the fastest, 10 subject to a cycle time of the switching speed of the slowest. The examples of the present invention operate in a similar fashion to the device of figure 3, in that the image sequence is run three times on the image source 5, with each of the apertures 7 being activated in turn on the 15 shutter 8 once for each time the sequence is played, the f ilter 12 being switched between colours in advance of the opening of the aperture 7 80 that it has completely changed to the next colour prior to them being made visible to the viewer .
COLOUR AUTOSTEREOSCOpIC l7ISpr 2,y The present invention relates to three dimensional ' autostereoscopic displays. Such autostereoscopic displays 5 can be made from a high frame rate two dimensional display and a device which makes the picture on the two dir-n~:ion~
display visible from different directions.
To display an autostereoscopic three dimensional image, a series of views of the object to be imaged are lO required. These might be captured by, for example, surrounding a solid object with an array of conventional cameras .
With such systems, each view in the series is put up on the two dimensional display in turn and made visible lS from a particular general direction. If the series is repeated quickly enough that the human eye perceives no flicker, the apparent effect is a display whose image content will depend on from where the human eye looks. By appropriate matching of view to direction of viewability, 20 it is possible to recreate the three dimensional image on the display.
one way of making such a display is to use a cathode ray tube as the two dimensional display, and a lens and a shutter as the device which limits the field of view of the 25 picture on the display.
The lens forms a virtual image of the cathode ray tube. The shutter, which reduces the field of view of the image, is positioned adjacent to the lens.
If the position of the aperture in the shutter can be 30 changed rapidly, the angle from which the image can be seen may be varied as different pictures are presented in turn for display on the CRT screen. Each picture can be the view of some scene taken from a chosen viewpoint. So long as the picture for each direction is repeated sufficiently 35 frequently, typically at least 50 Hz, and the shutter is stepped in sequence with the view on the CRT display, then different views will be seen from different positions and _ _ _ _ _ . . . . . .
W095/14353 21 7657~ r~ A?~
a three dimensional im;-ge will be observed. There ~re several alternative optical and image forming arrangements that are operationally equivalent to the description given above. Implementations can consist of 2 dimensional image 5 forming devices made from an LCD or from a CRT. The shutter can be made from an LCD. The arrangement can place the shutter between the image f orming device and the observer or can position the image forming device between the shutter and the observer. The light can be collimated 10 or non-collimated. In a presently preferred implementation, the image forming device is a CRT and a viewing lens i5 added between the viewer and the shutter to narrow the pencils of rays passing through the aperture into near-parallel beams.
A number of devices for producing a colour 3D display employing the above principles have been proposed. One such way of making a colour three dimensional display is to have a colour CRT. However conventional colour CRT's are not bright because they incorporate shadow masks. Since the 20 shuttering system absorbs a lot of light the CRT in this system needs to be bright, requiring a great deal of power, and brighter than available by current masking techniques.
Another way of making a colour three dimensional display is to use dichroic mirrors to combine the images 25 from one red, one green and one blue CRT. The problem is that, at least in current three dimensional displays, the imaging lens is large, and there is little space for dichroic mirrors. Furthermore, it becomes ne~ Ary to register the CRTs so that the position of each pixel is the 30 same on each CRT. The whole system is bulky, heavy and expensive because three times as many I - t_s are needed .
The bulk and expense of three CRT's can be avoided by using one C~T with a white phosphor, then f iltering the 35 emitted light so that rays of each of the primary colours are transmitted in turn. The disadvantages of this approach are that the CRT needs to operate three times f aster than ~W095/14353 - ~1 76574 f~ 51.'0~'t~
otherwise, it needs to be ~righter than otherwise, and a f ilter which can switch between the primary colours is required .
A f ilter which switches between the primary colours S has been made for a colour two dimensional display. It might seem that the obvious way to make a colour three dimensional display would be to place this filter over the front of the three dimensional display. Colour images miqht be produced on a black/white three dimensional display 10 by placing a f ilter against the front which switches through the primary colours. The problem is that the liyuid crystal of which present switching colour filters are made cannot switch yuickly enough.
When the f ilter is used on a two dimensional display 15 the CRT displays the three primary colour ~ ntS of the picture one by one. Ideally the filter should change colour in the time interval between the end of the display of one primary colour and the beginning of the display of the next. This time interval is short and even on the two 20 dimensional display the filter is not fast enough for this purpose .
In fact the filter is divided into horizontal bands which can be switched i nrl~r-n~l-ntly. The idea is that as the CRT electron beam writes each picture from the top of 25 the screen to the bottom, the horizontal bands of the filter are also switched one by one, from top to bottom.
Provided each band begins switching immediately after lines adjacent to it have decayed, there is sufficient time to complete switching before the adjacent lines are written 30 with new information.
This solution works for the two dimensional display, but the frame rate of the CRT in the three dimensional display is much higher. There is therefore less time before each line is rewritten, and this time is insufficient for 3 5 the f ilter to switch .
An alternative to using a switching colour filter would be to make a wheel comprising a red, ~-reen and blue _ _ _ _ . _ _ . . . _ . . _ _ . . .
W095/14353 - 2 l 76574 P~ r~
filter and spin this in ~ront of the screen. This might work with a two dimensional display because the wheel need only spin at 60 Hz. With a three dimensional display with 8 views, for example, the wheel would have to spin at 480 5 Hz, this would be impractical.
The presently available switching colour filters are slow because they are based on slow-switching liquid crystals. The liquid crystals in the shutter used in the three d;r^~ AnAl display switch much more quickly. It has 10 been suggested that it might be possible to conf igure the shutter to switch each slit through each of the primary colours in turn before closing that slit and opening the next. Colour images might be produced on a black/white three dimensional display by making the shutter f ilter the 15 primary colours in turn while each slit is open.
Unfortunately, shutters which work in this way are not available at present.
It is useful to consider if a pair of spinning wheels could be conf igured to behave like a colour-switching 20 shutter. Such a system is ~l; cc~lcsed in ' Wireless World, Feb 1942-Stereoscopic colour TV~ . In a system with a wheel with a slit spinning so as to scan the slit in the focal plane of the collimating lens, with a colour wheel placed adjacent to this slit, the colour wheel spinning at a 25 higher rate so that at each slit position light is filtered to produce each of the primary colours.
The problem with this proposed system is that the shutter slit does not move from position to position, but is always moving. So the slit will be at a slightly 30 different position as each of the colour filters passes it.
This will produce a registration problem, there will be positions at which an eye will see, for example, the red ~ AAt of one view superposed on the blue and green components of a different view. This would be quite 35 unsatisfactory.
According to the present invention there is provided a polychromatic three dimensional display comprising:
-~095114353 ~1 76574 P~,l,. ~A`7~48 a f irst image source;
a second image source, the second image source being adapted to reduce selectively the f ield of view of the - f irst image source to generate thereby a time multiplexed 5 three ~l;r -irn~l autostereoscopic image; and a switching colour filter ~i.cposr~ adjacent to the second image source and comprising a plurality of regions each switchable between different colours to enable colour modulation of the generated image.
Preferably the first image source is a spatial light modulator, and the second image source is a Sr~nn;ng light source which selectively illuminates the first image source from one of a plurality of positions. Alternatively, the f irst image source is a monochrome or white rhn5rhnr 15 cathode ray tube or similar device, and the second image source is a shutter comprising a plurality of in-lr~ronr~r~ntly activated apertures.
Preferably, there is also provided an imaging lens positioned between the two image sources. The imaging lens 20 may be either single or multi-element, and allows greater optical design freedom, together with the possibility of producing large images from ~ .^nts of reduced size.
A collimating lens may also be provided to provide a viewer with collimated light to improve the 25 autostt~ oscu~ic effect of the display.
The filter may include a rotatable disc comprising a plurality of differently coloured regions, but is preferably comprises a plurality of regions that are individually switchable between a plurality of colours.
30 With this latter arrangement, for displays where the second image source is a shutter, there may also be provided control means for controlling the activation of the switching colour filter strips and shutter ape~ Lu ~s so that each strip starts switching to the next colour 35 immediately after the termination of the view which passes light through that strip.
WO 95114353 , 2 1 7 5 5 7 4 , "~
Pre~erably the colour f ilter has portions ~orL~lu~ lin~ the three primary colours.
One example of the present invention will now be described with reference to the a-_ -nying drawings in 5 which:
Fig. 1 is a schematic diagram showing the basic principles of an autostereoscopic three dimensional display;
Fig. 2 is a diagram showing a prior art example of a 10 monochrome autostereoscopic three dimensional display;
Fig. 3 is a colour adaptation of the display of figure 2;
Fig. 4 is a prior art polychromatic autoste~eos~u~ic three dimensional display employing a spinning disc;
lS Fig . 5 is a schematic diagram of a f irst example autostereoscopic poly.~ ""atic three dimensional display according to the present invention;
Fig. 6 is a schematic diagram of a second example autostereoscopic polychromatic three dimensional display 20 according to the present invention; and Fig. 7 is a schematic diagram of a third example autostereoscopic polychromatic three dimensional display according to the present invention.
Figure 1 shows the basic concept of a known three 25 dimensional display. Pictures of an object are formed by cameras 3 ranged round the object 2 and pointing at it from different directions. One picture at a time is reproduced on the display 1. The display 1 can conf ine the direction f rom which this picture is visible . It does this so that 30 the direction of visibility matches the direction of the camera from which the picture is received. Other pictures are shown from other cameras 3 in a similar manner. Once a picture from each of the cameras 3 has been shown, the sequence is repeated. The rate of repetition is such that 35 the display of each picture to each direction will appear continuous to an observer 4 inspecting the display from different angles.
Wo 951143S3 ~ 1 7 6 5 7 4 p~
Whenever collimated light i 1 l1~nin7~tes the observer 4, he will see the picture on the display. However each of the observer's eyes will be illuminated by collimated light travelling in different directions. So each eye will see a different picture. The three dimensional image displayed will therefore be of the type described with reference to f igure l .
In the prior art system of f igure 2, a cathode ray tube (CRT) 5 is used as an image source. Light from the image source 5 passes through an imaging lens 6 and an aperture 7 in a shutter 8. The shutter 8 comprises an array of i ~ op~n~lP~ltly activated apertures 7 . The light then passes through a collimating lens g to be viewed by an observer. A different aperture 7 is opened for each of the images that are displayed on the image source 5, so that a viewer perceives each of the images to be from a source of a different position and a monochrome three dimensional display is produced.
Figure 3 shows the monochrome three dimensional display of figure 2 adapted to be used a colour three dimensional display by the additional of a colour filter lO. The colour filter lO switches between the three primary colours in turn, and the sequence of images displayed in the image source 5 is repeated three times, once for each of the primary colours. As mentioned above, such a system has the serious problem that a switching times of the image source 5, shutter 8 and particularly the colour filter lO must be very small so that no flicker is observed by the viewer.
In the prior art system of figure 4, the moving slit shutter 8 is provided by a spinning disc, and the colour is produced by the rotation of a spinning disc ll that is divided into three portions, each of the portions being coloured according to one of the three primary colours. In this example, the filter disc ll is spun at high speed to produce three 5~1rpO5c~7 ] y identical images in the three primary colours, which are perceived by an observer to be Wo95/14353 2 1 76574 a single image of combined colour. Unfortunately, as the slit 7 is continuously moving, the three coloured images will be perceived to be coming from slightly different positions, so that they will not overlap perfectly and a 5 full three dimensional effect will not be produced.
In the first example of the present invention shown in Fig . 5, the display has a f irst image source 5, which is a spatial light modulator provided by a liquid crystal display or similar device. The device also includes a 10 scAnnin~ light source 8 and spinning disk filter 12. There is also provided an imaging lens 6, which is not essential, but which provides greater c~nronont design freedom. In operation the f irst image source 5 displays a series of images of an object from different viewpoints, and, for 15 each image displayed, a different portion of the light source is activated, illuminating the image from one direction and malcing it appear to come from a different position. As with the prior art examples, with each of the images being produced at a rate at which the eye perceives 20 no flicker, an autostereoscopic display is produced.
However, as there is provided a colour filter 12 between the light source 8 and image source 5, a series of colQur modulated images will be presented to a viewer. The colour f ilter 12 must spin at a speed which ensures that the 25 illuminating light is modulated to the correct colour for the image being presented, but as only one of the light sources 8 is activated at any one instant, the rotation of the colour filter 12 can follow the activation of the individual light sources 8, providing a complete series of 30 images for a first colour, and enabling the filter 12 to have rotated to the next colour by the time that each of the sources 8 has been activated. This greatly reduces the n,~C-~cc:Ary spinning speed for the filter.
Fig. 6 shows a second example of the present invention 35 which employs very similar principles to that of the first example, but which, in place of the spinning colour filter 12 has a colour f ilter comprising a plurality of _ _ _ _ _ _ _ _ .. _ . ... _ .. .... . .. . . ... .
WO951143~3 ~ ~ 76~7~ P~ r~48 individually switchable regions 13. Each of these regions 13 can be switched between one of a number of colours, in this example red, green and blue An example of a device with such characteristics is a NU 700S colour shutter from 5 Tectronix Ltd. In this example, the light source 8 and image source 5 operate in a similar fashion to that of the first example, but the filter is aligned with the individual light sources. In operation, each of the regions 13 of the filter 12 is activated to change colour 10 immediately after its ~ u, Le:,~onding light source has been de-activated, so that the time period in which each region must change to the next required colour is r-~;mised. This enables the employment of a filter with a reduced switching speed for each of its regions.
In the example of the present invention shown in f igure 7, a f irst image source 5, imaging lens 6, shutter 8 and collimating lens 9 are provided, in addition, a switching colour f ilter 12 is also provided . The imaging lens 6 and collimating lens 9 are not essential to the invention, but, as mentioned above, enable greater design freedom and components of reduced size to be employed. The switching colour filter 12 is positioned between the imaging lens 6 and the shutter 8 and, as with the second example, comprises an array of individually switchable regions 13, each of the regions being able to be switched between the primary colours. This example may, alternatively, employ a spinning disc filter of the type described with ref erence to f igure 5, in place of the switchable strip colour filter 12.
As previûusly mentioned, spinning disc colour filterS
would normally have to be spun at great speed to be employed in an autostereoscopic display, but, with the examples of the present invention which employ such filters, this speed is greatly reduced by the employment of only a fraction of one of the coloured apertures in colour modulation at a particular instant. Also, as previously mentioned, the switching time of switchable colour filters _ _ _ _ . . .. . .. _ ... .... . _ _ _ _ . _ _ . _ is slow, but in the two examples of the present invention which employ such filters, this is overcome by individually switchable strips 13, which can be activated prior to their corresponding aperture 7 being opened in front of them. As 5 each of the strips is only visible for a short period of time, a larger switching time is available for activating them and changing their colour. Different speed of switching colour and aperture can be exploited to give the combined effect on the two at the speed of the fastest, 10 subject to a cycle time of the switching speed of the slowest. The examples of the present invention operate in a similar fashion to the device of figure 3, in that the image sequence is run three times on the image source 5, with each of the apertures 7 being activated in turn on the 15 shutter 8 once for each time the sequence is played, the f ilter 12 being switched between colours in advance of the opening of the aperture 7 80 that it has completely changed to the next colour prior to them being made visible to the viewer .
Claims (13)
1. A polychromatic three dimensional display comprising:
a first image source for displaying a series of images of an object from different viewpoints;
a second image source, the second image source being adapted to reduce selectively the field of view of the first image source to generate thereby a time multiplexed three dimensional autostereoscopic image from said series of images; and a switching colour filter, disposed adjacent to the second image source and comprising a plurality of regions switchable between different colours to enable colour modulation of the generated series of images.
a first image source for displaying a series of images of an object from different viewpoints;
a second image source, the second image source being adapted to reduce selectively the field of view of the first image source to generate thereby a time multiplexed three dimensional autostereoscopic image from said series of images; and a switching colour filter, disposed adjacent to the second image source and comprising a plurality of regions switchable between different colours to enable colour modulation of the generated series of images.
2. A display according to claim 1, wherein the first image source is a spatial light modulator, and the second image source is a scanning light source which selectively illuminates the first image source from one of a plurality of positions.
3. A display according to claim 1, wherein the first image source is a white phosphor cathode ray tube or similar device, and the second image source is a shutter comprising a plurality of individually activated apertures.
4. A display according to claim 1, 2 or 3, wherein there is further provided an imaging lens positioned between the two image sources.
5. A display according to claim 4, wherein the imaging lens is a single element lens.
6. A display according to claim 4, wherein the imaging lens is a multi-element lens.
7. A display according to any of the preceding claims, wherein there is further provided a collimating lens to provide a viewer with collimated light.
8. A display according to any of the preceding claims, wherein the filter includes a rotatable disc having a plurality of differently coloured regions.
9. A display according to any of claims 1 to 7, wherein the filter comprises a plurality of regions that are individually switchable between a plurality of colours.
10. A display according to claim 9, wherein each of the regions are rectangular and adjacent to one another.
11. A display according to claim 9 or 10, when dependent upon any of claims 3 to 7, wherein there is further provided control means for controlling the activation of the switching colour filter strips and shutter apertures so that each strip starts switching to the next colour immediately after the termination of the view which passes light through that strip.
12. A display according to any of the preceding claims, wherein the filter has portions corresponding to the three primary colours.
13. A display according to any of the preceding claims, wherein the first image source displays real two dimensional images.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB939323878A GB9323878D0 (en) | 1993-11-19 | 1993-11-19 | Colour 3d display |
| GB9323878.0 | 1993-11-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2176574A1 true CA2176574A1 (en) | 1995-05-26 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002176574A Abandoned CA2176574A1 (en) | 1993-11-19 | 1994-11-18 | Colour autostereoscopic display |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5825337A (en) |
| EP (1) | EP0729690A1 (en) |
| JP (1) | JPH09505156A (en) |
| AU (1) | AU683324B2 (en) |
| CA (1) | CA2176574A1 (en) |
| GB (1) | GB9323878D0 (en) |
| TW (1) | TW274674B (en) |
| WO (1) | WO1995014353A1 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW373095B (en) * | 1995-06-15 | 1999-11-01 | Canon Kk | Method for driving optical modulation unit, optical modulation or image display system |
| WO1997018677A1 (en) * | 1995-11-16 | 1997-05-22 | Asd (Holdings) Limited | Autostereoscopic video camera |
| US6329963B1 (en) * | 1996-06-05 | 2001-12-11 | Cyberlogic, Inc. | Three-dimensional display system: apparatus and method |
| US5973727A (en) * | 1997-05-13 | 1999-10-26 | New Light Industries, Ltd. | Video image viewing device and method |
| US6163308A (en) * | 1997-08-08 | 2000-12-19 | Philips Electronics North America Corporation | Method and apparatus for minimizing visual artifacts caused by the pixel display of a video image |
| US7239293B2 (en) * | 1998-01-21 | 2007-07-03 | New York University | Autostereoscopic display |
| DE19836886C2 (en) * | 1998-08-14 | 2002-01-03 | Dieter Just | Process for autostereoscopic image generation and display |
| EP1758088A3 (en) * | 1998-12-01 | 2008-02-27 | Seiko Epson Corporation | Color display device and color display method |
| KR100625029B1 (en) * | 1999-05-28 | 2006-09-20 | 엘지.필립스 엘시디 주식회사 | Apparatus For Display stereoscopic Image |
| US7085049B2 (en) * | 1999-07-19 | 2006-08-01 | Lg.Philips Lcd Co., Ltd. | Multi-mode stereoscopic image display method and apparatus |
| US20080024598A1 (en) * | 2000-07-21 | 2008-01-31 | New York University | Autostereoscopic display |
| WO2004016460A1 (en) * | 2002-08-19 | 2004-02-26 | Koninklijke Philips Electronics N.V. | A display system for displaying images within a vehicle |
| DE10249815B4 (en) * | 2002-10-24 | 2014-01-02 | Infitec Gmbh | Stereo projection system and projection device for it |
| TWI347453B (en) | 2007-06-23 | 2011-08-21 | Ind Tech Res Inst | Hybrid multiplexed 3d display and a displaying method thereof |
| US9116357B2 (en) | 2007-06-23 | 2015-08-25 | Industrial Technology Research Institute | Hybrid multiplexed 3D display and displaying method thereof |
| CN202040748U (en) * | 2011-03-08 | 2011-11-16 | 绎立锐光科技开发(深圳)有限公司 | Optical wavelength converting wheel component |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4758884A (en) * | 1986-05-19 | 1988-07-19 | Kaiser Electronics | Electronically switched field sequential color video display having parallel color inputs |
| GB8716369D0 (en) * | 1987-07-10 | 1987-08-19 | Travis A R L | Three-dimensional display device |
| US5086354A (en) * | 1989-02-27 | 1992-02-04 | Bass Robert E | Three dimensional optical viewing system |
| GB9006179D0 (en) * | 1990-03-19 | 1990-05-16 | Ridgway Michael | 3-d system |
| DE69219434T2 (en) * | 1991-11-05 | 1998-01-22 | Sharp Kk | A three-dimensional imaging system |
| DE4235753A1 (en) * | 1992-10-23 | 1994-04-28 | Zeiss Carl Fa | Imaging system for stereoscopic vision |
-
1993
- 1993-11-19 GB GB939323878A patent/GB9323878D0/en active Pending
-
1994
- 1994-11-15 TW TW083110561A patent/TW274674B/en active
- 1994-11-18 CA CA002176574A patent/CA2176574A1/en not_active Abandoned
- 1994-11-18 EP EP95901513A patent/EP0729690A1/en not_active Withdrawn
- 1994-11-18 US US08/648,181 patent/US5825337A/en not_active Expired - Fee Related
- 1994-11-18 JP JP7514317A patent/JPH09505156A/en active Pending
- 1994-11-18 AU AU10713/95A patent/AU683324B2/en not_active Ceased
- 1994-11-18 WO PCT/GB1994/002548 patent/WO1995014353A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| GB9323878D0 (en) | 1994-01-05 |
| EP0729690A1 (en) | 1996-09-04 |
| AU1071395A (en) | 1995-06-06 |
| JPH09505156A (en) | 1997-05-20 |
| WO1995014353A1 (en) | 1995-05-26 |
| TW274674B (en) | 1996-04-21 |
| US5825337A (en) | 1998-10-20 |
| AU683324B2 (en) | 1997-11-06 |
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