CA2344042A1 - Device for producing three-dimensional images - Google Patents

Abstract

The invention relates to a device for producing autostereoscopically observe d images with perspective views of the object field thus detected. The surface of the screen is composed of individual segments (pixels) that can produce three additive base colours. The pixels constitute the head of a height- adjustable pixel carrier. The pixel carriers can be individually controlled and adjusted at various heights (pixel heights). By controlling the pixel carriers in this manner, the pixels can be raised/and or lowered. Height effects can be produced in both the direction of the viewer and in an opposi te direction. Spacial depth information, e.g. from a z buffer, can be transform ed proportionally into pixel heights, i.e. without any intermediate steps. Current computer technology enables the image depth information to be used directly to convert said information into relief-shaped image depth, i.e. th e colour signals of the image, toegether with the image depth of the objects a s represented by the pixel heights, complete each other to form a new quality image.

Description

°franslation from the German lane ua a Page Description 1. Device for the creation of three-dimensional pictures.
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2. The invention concerns a picture-carrier for tlhe generation of auto-stereoscopically observed pictures which give perspective views of the recorded field of view of the object.

3. US 4 571 616 and DE 35 29 819 describe projection devices which have static screen surfaces in which the screen is grouped in cylindrical lens-shaped rasters so as to create stereoscopic pictures. In this process, pictures are split into vertical lines anc~ projected onto the back of the screen. The lines can then be directionally selected through the ~s cylinder lens set in front of them, with the result that the observer is provided with the effect of viewing a spatial picture. Anaglyph procedures are also known in which two latera111y displaced and superimposed projected images create a three-dimensional effect.
Here the two projected images are viewed with the aid of colour filter ao spectacles, whose lenses are coloured in the same colours as the two projected pictures. Another recognised technique is that of shutter-spectacles, which create a three-dimensional picture by releasing the view of the screen to the right and then to the left eye at separate intervals, and in synchronisation with the screen presentation.
as Another well-known device is the three-dimensional display described in JP 07 - 64 020. In this, several simple objective lenses are placed on a display surface. They include a convex lens with a short focal length, a light source, and an elastic drive positioned between the two. Using the flexible drive allows the distance between the convex lens and the light source to be varied. This changes the position of the image of the light source conveyed through the convex lens, and so produces imaginary pictures. The device also permits these simple objective lenses to be arranged in geometric shapes, e.g. cylindrical or ball-shaped bodies, so that the projection of the imaginary 'front or re<~r picture' can be made 3s available to the observer through a field of ob~;ervation of 360°.

Translation from the German lanc ua a Page In this type of direct projection technique for thE; eye, the estimate of distance of an object is related to the size of its perceived image.
These techniques call up perceived images whiich appear to be spatial, using zooming techniques by means of simple objective lenses. They s use a perceptivelpsychological effect (without tlhe use of spectacles or similar aids), which is based on an empirical, visually attained memorisation.
US 5793918 describes a device with light-conducting optics /glass fibres which can be moved longitudinally by means of drives, and which ~o are mounted on a curved display / projector, and transmit the picture which is created in the background by this projector to the observer at the device's - / relief surface.
The glass fibres and their related motive drives which are mounted on this curved screen I projector are grouped together (in the direction of ~s the observer), and are moved by a holding device so that they create a height-structured surface, comparable to a real object.

4. One disadvantage of the anaglyph procedurE: referred to above, is the high loss of colour components. With the shunter-spectacle device ao described earlier, there is the disadvantage that special glasses have to be worn, and that, because of the way the picture is divided, only half of the picture refresh rate can be used. Further, with US 4 571 616 and DE 35 29 819 the three-dimensional picture efi~ect is proportionally restricted, in that the viewing angle and the distance to the screen are zs changed so as to be able to perceive larger spatial perspectives of the picture object. With this latter procedure, greater technical input is necessary, in order so to increase the spatial picture effect, that concealed picture contents can be transmitted to the observer. This is done by either replicating the vertical lines to create additional 3o projections, or by modifying them to the observation position (calculation}. A disadvantage of this procedurE~ is that the stereoscopic effects are lost if the screen is turned around a~ screen orthogonal. This disadvantage comes into effect with rotatable screens or screens with horizontal screen surfaces ('Responsive Worklbench' - Chip 5198 3s S.32), which are used by several observers at the same time. With the procedures mentioned above, ;ii ,~u~.~

°'~ Translation from the German lanc u~ aae Page with the exception of the shutter-technique, only the most diverse variations of vertical line raster procedures come into play.
The method of direct projection techniques using simple objective lenses, when compared to the above procedures, leads to substantial s reductions in quality for a greater technical and financial expenditure, and this substantially increases with the increa:~ing complexity of the picture contents to be conveyed.
This enormous financial outlay is substantially iincreased with devices that are based on US 5793918, together which also give rise to ao increasing productive effort and decreasing quality of the picture representation.
This is explained by the fact that a complicated) optical mechanism is mounted on a specially curved screen I projector.
This screen / projector creates pictures in the background, which are to ~s be conveyed to the observer by means of height-adjustable optics glass fibres. Since however the non-light conducting drives as well as the light-conducting optics have to be mounted' on the screen I
projector, the screen / projector must have a vE~ry large surface and must be curved (at considerable effort), in order to shape it in a form ao suitable for use.
Added to this is the problem that the picture for this complex, universally-curved screen I projector has to be specially computed, in order to compensate for the comparitively IargE: resulting blind spots of the drive supports opposite the glass fibres thE:mselves.
2s The physical characteristics of the optics / gla~~s fibres mounted on the screen I projector also lead to the disadvantage that only a very low rate of 1124 second can be achieved. This is directly related to the development of longitudinal oscillations in the fibres. This fibre oscillation carries through to the ends of the picture relief and appears 3o as uncontrollable surface resonances with every change in position.
These surface resonances cannot be prevented by the bundling mentioned earlier. The guidance grid which is provided to stabilise the ends of the glass fibres tends to favour this negative effect through the guide opening tolerances provided.
3s The unintended surface resonances cause an irritating image perception to the observer (whip effect), which become stronger with increasing Translation from the German lanc u~ age Page picture relief depths and more complex, rapidly changing picture contents with sharp sloping surfaces.
If one were for example to move a simulated grid over the image area, considerable changes in height of the glass fibres are needed at short s intervals to each other in order to do justice to the displayed object.
This leads to a high static charging of the glass, fibres, and causes the related field effects and the production of heat. All these either have to be critically determined in all the components referred to which concern the observer and his contact with them, or havE; to be resolved at further financial expenditure.
It can be concluded from the above that, in order to keep undesirable side-effects to a minimum, only limited picture contents can be represented and these only in a time-restricted cycle of the standard picture refresh frequencies.
~s This time-restricted cycle is also a result of the need to continually measure the positions of the individual glass fibres, compare them with the planned position and then correct them.
Zo 5. Given the present status of the technology, the need is to develop an electronic screen, without mechanically driven optics, and with a shallow construction depth, whose screen surface can be structured with a high frequency, and in which the light foir the representation of the picture can be directly generated in the screen surface, so that all as the drives lie behind the screen generation surface, in order to create a three-dimensional picture, in which no separate technical aids are needed to perceive the picture depth. The screen surface also has to be so formed that no fixed position of the observer is called for, that changes in the position of the observer do not call for the calculation of 3o a new picture, and that both are possible without restricting the quality of the perceived image. At the same time the tereoscopic effect must remain present even when the screen is pivotE;d around a screen orthogonal.
3s 6. This task may be solved by inventing a device which is developed in accordance with the defining characteristics of claim 1.

Translation from the German lanc uI aae Page 7. The screen should preferably be formed from single LED-segments (pixels), where each pixel can generate the thrE;e additive primary colours. As an alternative to using LED's for the pixels, other light generators of suitable dimensions may be usedl as the optically active s elements. Each single pixel is mounted on the head of a height-adjustable pixel-carrier. These pixels can be moved to different heights (pixel heights) independently of each other by controlling the pixel-carriers. The pixel heights have different zero-positions (these correspond to the zero level) and can be moved to different pixel heights in the direction towards and away from the observer. The zero position is not necessarily identical with the starting position, since the pixel levels can be moved to a planned position, which then forms the corresponding zero level. With suitable control instructions the pixels can be lowered and /or raised below or above t;he zero level. The pixel ~s carrier can for example be so shaped, that it consists of several piezo-crystals connected in layers, so that a cumulative height effect can be obtained through suitable control instructions. These height effects can be produced at the zero level and at the starting position, as well as in the direction towards and away from the obsen~er. In this way the ao spatial depth information from e.g. a z-buffer c<~n be proportionally converted into pixel heights, that is without any other intermediate steps. With other applications (e.g. stadium diaplays, advertising billboards etc.), other motive units with suitable: short control times (e.g.
using other field-electrical effects etc.) can be used instead of the piezo-as crystals referred to.
8. The advantages of the invention are to be found in the fact that the standard flat screen techniques, such as in e.g. LED-flat screens, can be directly utilised, since transport motors can be placed behind each 3o single pixel of this LED surface and thus the LED's can be placed at different heights to each other.
The resulting height profile provides a clear spatial depth perception of the picture signal when observed from the side, and also when seen from all other viewing positions.
3s With the presently available computing technology, the data on picture depth can thus ii Translation from the German langyaae Page be used directly (stored e.g. in the z-buffer of 3--D graphic cards), so as to convert the data into relief-type picture depths - i.e, the picture colour signal combines with the picture depth of the object (represented through the pixel heights) to give a picture with a new quality. This new s quality of picture results from the physical reali:>ation of the z-axis of the mathematical model (as stored e.g. in the z-buffers referred to), multiplied by the standardised factor.
The greater the difference in height level and its breakdown into single levels, the greater is the possibility of generating an actual spatial depth, which corresponds to the depth simulatE;d by colouration and brightness. In addition, it is possible to set piezo-crystals into high-frequency oscillations and so to overlayer the image data such that images can be transmitted to the observer which can be computed or perceived from different positions, i.e. that every relief structure can be ~s assigned to a picture element at a synchronised rate.
The term 'relief structure' used above is defined by the screen surface formed by the pixel matrix with a pre-determined height for each individual pixel.
Through the use of conventional flat screen production techniques (e.g.
Zo as for LED-flat screens) a high unit rate of procluction can be achieved at a low cost.
9. An example of the application is given diagrammatically in Figure 1.
This shows a single LED-segment from a device for the generation of as three-dimensional pictures. In this, the pixel-c<~rrier (3) contains a piezo-element (1 ), which on application of a voltage extends in the direction (7) of the observer position. The pixel-carrier (3) has a foot (6), over which a further piezo-element (2) extE;nds like a cloak, and which bears at its end the whole mechanism and which is fixed at one 3o end to an assembly board (4) and which permits a further basic movement (8) away from the observer. The pixel-carrier (3) has as a pixel (12) a light-source-generating head which is formed from three LED's (5) in the colours red, green and blue. The whole device for the generation of three-dimensional images consists in this case e.g. (for 3s the application as an advertising board) of a relatively large 480 x 270 matrix of the segments referred to. Its size is '160 cm x 90 cm.

Translation from the German lan< u~ age Page As a further example of an application, Figure 2 shows the schematic representation of a single LED-segment of a device for the generation of three-dimensional images, in which the pixel-carrier (3) runs through three linearly arranged electrical coils (9). The pixel-carrier (3) has as a s pixel (12) a light-source-generating head which is formed from three LED's (5) in the colours red, green and blue. An iron core (10) is integrated in the pixel carrier. The head is positioned at the appropriate height level by the action of the electrical coils on the iron core. In addition the pixel carrier (3) also has a coil spring (11 ) which moves the m pixel carrier back to the starting position when it is not being controlled.

Claims (4)

Page Claims

1. Device for the representation of three-dimensional pictures whose characteristic is that it is formed from the combination of individual optically-active, light-source-generating pixels (12), which form a screen surface in which each single pixel (12) is sited on a pixel carrier (3) whose height is adjustable relative to this screen surface.

2. Device for the representation of three-dimensional pictures in accordance with claim 1, whose characteristic is that the pixels (12) can be placed at different heights independently of each other.

3. Device for the representation of three-dimensional pictures in accordance with claims 1 and 2, whose characteristic is that the pixel heights can be combined in a zero position, corresponding to the zero level, and can then be moved from there in the direction of the observer (positive) and / or in the reverse direction (negative).

4. Device for the representation of three-dimensional pictures in accordance with claims 1 and 2, whose characteristic is that on use of the device the pixel (12) can be moved to a pixel height (zero position), and can be sent in the direction of the observer (positive) and / or in the reverse direction (negative).