Title of Invention

METHOD AND APPARATUS FOR FORMING A NON-SOLID PROJECTION SCREEN OR PROJECTION VOLUME

Abstract A method for forming a non-solid projection screen (3) or projectionvolume, in which method light scattering / reflecting scattering centers(4) are supplied to and / or produced to a substantially laminar transfer flow (2), said light scattering / reflecting scattering centers being transferred by said transfer flow (2), wherein the scattering centers (4) are supplied and / or formed to the transfer flow (2) to the central / inner parts thereof that remain laminar, away from the direct vicinity of the interface between the transfer flow (2) and the area surrounding thereof. An apparatus for implementing the above method is also disclosed.
Full Text METHOD AND APPARATUS FOR FORMING A NON-SOLID PROJECTION
SCREEN OR PROJECTION VOLUME
The present invention relates to a method for forming a projection screen or a
if*" ■
projection volume. The invention also relates to a device for implementing the
aforementioned method.
In this context, a projection screen refers generally to a substantially
two-dimensional surface with such light reflection and/or light scattering
properties that a moving or still image, or other performances or effects
based on the use of light, can be reflected on the surface by means of
a projector, light effect device, laser device, or the like. In a corre-
sponding manner, a projection volume refers to a substantially three-
dimensional object that can be illuminated in a suitable manner to produce
three-dimensional patterns.
The most commonly used projection screens are manufactured of
fabric, painted wood, metal, plastic, or other solid material. A well-
known example of such a solid projection screen is the movie screen.
However, using the above-mentioned projection screens involves
certain limitations. For example, in different outdoor or indoor perform-
ances, large, temporary projection screens are needed, which must be
assembled and disassembled fast. In certain situations, assembling
and disassembling the projection screens must be carried out also
during an actual performance. The prior art recognizes various non-
solid projection screens that enable more versatile uses compared to
traditional solid projection screens.
US patent publications US 5,067,653, US 5,270,752, US 5,989,128
US 6,092,900, German patent publications DE 476372 and
DE 3130638, Swiss patent publication CH 647605, British patent publication
GB 2220278, and French patent publication FR 2773229
describe various projection screens formed typically of fog. They
generally describe spraying of fog or steam condensating into fog, or

gas planarly from nozzles, wherein images, or the like, can be projected
on the thereby generated planar fog surface either from the front
of the projection screen or from the back of the projection screen relative
to the observer.
A problem involved in these projection screens composed of fog, or the
like, is their tendency to disperse, i.e., the planar quality of the projection
screen deteriorates as the distance grows to the nozzles used in
forming the projection screen. This is due to the friction caused by a
fog flow of the surrounding still air and to the turbulence produced on
the surface of the flow formed by the projection screen as a result of
this. Obviously, as the planar quality of the projection screen deteriorates,
the image quality deteriorates respectively.
This problem is subject to discussion particularly in the aforementioned
patents US 5,067,653 and US 5,270,752. In said patents, both sides of
the projection screen are provided with air curtains, i.e. air flows that
are parallel with the flow formed by the projection screen, wherein the
task of these air curtains is to limit the fog flow between the air curtains
as planar as possible.
Japanese patent publication JP7056236 introduces a different kind of
solution for maintaining the planar quality of the projection screen. In
the solution introduced in said patent publication the projection screen
is formed by blowing fog or smoke from the nozzles in a manner that
the resulting flow is initially laminar. To keep the flow better in shape, a
separate suction apparatus is arranged on the opposite side relative to
the nozzles to suck the flow forming the projection screen. An aim of
this arrangement is to prevent dispersion of the flow caused by the
projection screen on the stretch between the blow apparatuses and
suction apparatuses.
However, in the aforementioned prior art solutions a significantly more
complicated apparatus structure is needed in forming the projection
screen, among other things, because separate air curtains are formed.
Nevertheless, in spite of the air curtains and/or the separate suction
apparatus, in practice the projection screen always disperses to some

extent, thereby deteriorating the image quality. The projection screen
tends to disperse more, the further away the distance to the nozzles:
grows. The larger projection screen is aimed to be produced, the more
difficult it becomes also technically to obtain a planar projection screen.
Moreover, prior art methods are ill suited for producing other kind than
merely planar projection screens. For example, steeply curved cylindrical
projection screens are difficult to form. Prior art solutions are still
mainly restricted to using fog (water) or smoke in forming the projection
screen. Prior art is also unable to provide functional solutions for
obtaining, in a satisfactory manner, projection volumes and three-
dimensional patterns projected on them.
The main purpose of the present invention is to provide a novel method
for forming a non-solid projection screen or projection volume in- a
manner that the problems present in the above-described prior art
solutions can be reduced or totally prevented.
To attain this purpose, there is disclosed a method for forming a non-solid
projection screen or projection volume, in which method light scattering /
reflecting scattering centers are supplied to and / or produced to a substantially
laminar transfer flow, said light scattering / reflecting scattering centers being
transferred by said transfer flow, wherein the scattering centers are supplied
and / or formed to the transfer flow to the central / inner parts thereof that remain
laminar, away from the direct vicinity of the interface between the transfer flow
and the area surrounding thereof.

extent, thereby deteriorating the image quality. The projection screen
tends to disperse more, the further away the distance to the nozzles
grows. The larger projection screen is aimed to be produced, the more
difficult it becomes also technically to obtain a planar projection screen.
Moreover, prior art methods are ill suited for producing other kind than
merely planar projection screens. For example, steeply curved cylindrical
projection screens are difficult to form. Prior art solutions are still
mainly restricted to using fog (water) or smoke in forming the projection
screen. Prior art is also unable to provide functional solutions for
obtaining, in a satisfactory manner, projection volumes and three-
dimensional patterns projected on them.
The main purpose of the present invention is to provide a novel method
for forming a non-solid projection screen or projection volume in. a
manner that the problems present in the above-described prior art
solutions can be reduced or totally prevented.
To attain this purpose, there is disclosed a method for forming a non-solid
projection screen or projection volume, in which method light scattering /
reflecting scattering centers are supplied to and / or produced to a substantially
laminar transfer flow, said light scattering / reflecting scattering centers being
transferred by said transfer flow, wherein the scattering centers are supplied
and / or formed to the transfer flow to the central / inner parts thereof that remain
laminar, away from the direct vicinity of the interface between the transfer flow
and the area surrounding thereof.

form in multi-colour, using conventional movie or video projectors, or
the like.
In another embodiment of the invention, material is used that scatters
light in a non-elastic manner, such as phosphorescent or fluorescent
particles, molecules or atoms. Hence, the scattering centres are made
to emit visible light by illuminating and activating them with suitable
radiation having higher energy level, i.e., radiation with shorter wavelength.
A benefit with this embodiment is that since the light of a certain
wavelength directed to the projection screen or projection volume, for
example ultraviolet light that is invisible to the human eye, activates
visible only certain defined areas in the target, this method can be used
for forming images or three-dimensional patterns that seem to be
floating in the air. Other areas of the projection screen or projection
volume can be arranged, using suitable scattering centres, for example
gas molecules, as scattering centres, to be substantially totally transparent
in the prevailing surrounding normal light, i.e., invisible to the
observer.

The solution of the invention enables forming of projection screens or
projection volumes of scattering centres moving along a gas or fluid
flow, the benefit of said projection screens or projection volumes being,
among other things, that they take a thin and cohesive form and
therefore show good image quality, that the apparatus required to form
them is simple, light-weight and easy to move and use, that the projection
screen and projection volume is very fast to form and disassemble,
and that also other types of projection screens than planar ones can be
formed.
The solution of the invention allows, while using, e.g., air for forming
the transfer flow and so-called dry fog as the scattering centres, it is
possible to create also walk-through projection screens and projection
volumes useful for example in forming so-called virtual spaces and
rooms (Projection-Based Virtual Environment, Cave Automatic Virtual
Environment). The projection screen constructions of prior art virtual
spaces are very expensive and difficult to form, assemble and amend.
^ The method according to the invention is suitable also for creating

various three-dimensional patterns, for three-dimensional visualisation,
for producing special effects and/or staging in different indoor or outdoor
scenes, or the like.
The following more detailed description of the invention by means of
examples will more clearly illustrate, for anyone skilled in the art,
advantageous embodiments of the invention as well as advantages to
be achieved with the invention in relation to prior art
In the following, the invention will be described in more detail with reference
to the appended drawings, in which
Fig. 1 illustrates the basic principle of the invention in a perspective
view when forming a substantially two-dimensional
projection screen,
Fig. 2 illustrates the embodiment according to Fig. 1 seen from a
direction opposite to the flow direction of the transfer flow,
Fig. 3 illustrates, in a manner corresponding to that of Fig. 2, a
principle view of an embodiment of the invention,
Fig. 4 illustrates, in a manner corresponding to that of Fig. 2, a
principle view of a second embodiment of the invention,
Fig. 5 illustrates, in a principle manner, the main principle of the
invention in a perspective view upon creating a three-
dimensional projection volume, and
Fig. 6 illustrates the embodiment according to Fig. 5 seen from a
direction opposite to the flow direction of the transfer flow.
Fig. 1 shows, in a principle manner, one apparatus according to the
invention for forming a projection screen. To form a transfer flow 2 of
gas or fluid as a substantially laminar, i.e., non-turbulence flow, any
suitable solution that is obvious to an expert in the field as such can
also be used. Principles of forming a laminar flow of gas or fluid are

very well known from study books of flow technique, and are therefore
not discussed here in more detail.
The projection screen 3 is formed of scattering centres 4 that are either
discharged from a supply means 5 and/or formed of source material/
materials discharged from said supply means 5. The scattering
centres 4 move inside a laminar transfer flow 2 in a manner that the
scattering centres 4 move along the transfer flow 2 in the inner part of
the transfer flow 2, which inner part remains laminar, without drifting to
the vicinity of the interfaces between the transfer flow 2 and the area
surrounding thereof, which interfaces always contain turbulence dispersing
the transfer flow 2 to some extent. However, the inner parts of
the transfer flow 2, being at a sufficient distance from the aforementioned
interlaces, keep their flow readily in laminar form, wherein the
projection screen 3 composed of scattering centres 4 remains, in turn,
well in shape.
To form an image on the projection screen 3, a projector 6 projects
light, which scatters from the scattering centres 4 in an elastic or non4
elastic manner, forming the desired image on the projection screen 3.
In the embodiments of the invention that are based on elastic scattering,
such as the Mie scattering, for example, the projector 6 can be a
movie projector, a video or computer projector, a luminous effect
device, laser device or any other device by which the desired still or
moving image and/or luminous effect could be projected also on an
ordinary solid projection screen, such as movie screen, for example, in
some embodiments of the invention the projector 6 can be also an illuminator,
spotlight, or a corresponding non-imaging light source.
In the methods of the invention that are based on non-elastic scattering,
such as fluorescence, for example, the projector 6 can be, for
example, a so-called laser projector or also some other laser or UV-
based light source, where, if necessary, a suitable arrangement is
arranged to deflect a beam/beams of light obtained from the light
source to project an image on the projection screen 3.

The transfer flow 2 is advantageously formed e.g. of air or water.
it is also possible to provide the device with a suction device 7, wherein
the transfer flow 2 can more readily remain laminar and/or the particles,
drops, or the like, operating as the scattering centres 4 can be
collected preventing them from spreading/accumulating to the environment
or drifting to block the path of the beam of light from the projector 6.
The suction device 7 also enables reuse of the scattering centres 4.
in one embodiment of the invention the flow device 1 and the suction
device 7 are connected to each other in a manner that the transfer flow
2 sucked by the suction device 7 is directed along a tube system, or
the like, back to the flow device 1. A benefit of this embodiment is that
while the same flow is hence recirculating in the apparatus, the disturbances
caused to the surrounding area, such as turbulence caused to
the surrounding area is reduced compared to a situation where the flow
device 1 and/or the suction device 7 discharge the flow continuously
into the surrounding space. Less disturbance directed towards the surrounding
area also work in favour in keeping the transfer flow in laminar form.
The scattering centres 4 contained in the transfer flow can be
recycled along with the flow from the suction device 7 back to the flow
device 1, or they can be removed from the flow by filtering prior to
recycling the flow back to the flow device 1.
Fig. 2 depicts, in a principle manner, the apparatus according to Fig. 1
as seen from a direction opposite to the flowing direction of the transfer
flow 2 (flowing direction towards an observer of the image). Fig. 2
shows more clearly than Fig. 1 the basic idea of the invention, i.e.,
even though some turbulence takes place in the interfaces 20 between
the transfer flow 2 and its surroundings, said turbulence does not
extend disturbing effect to the laminar flow of the inner and/or central
part of the transfer flow 2, where the supplied scattering centres 4 thus
constitute a coherent projection screen 3.
In accordance with Figs. 1 and 2, the laminar transfer flow 2 can be
formed either by using one flow device 1, or the transfer flow 2 can be

formed also in a manner shown in principle in Fig. 3 by using multiple
flow devices 1 jointly. Upon using a plurality of flow devices 1, the
speed, direction, composition and temperature of the transfer flows 2
caused thereby should be arranged to be as identical as possible,
wherein interfaces that tend to be formed between said transfer flows 2
causing turbulence are prevented. The substantially uniform projection
screen 3 that is now formed by using multiple flow devices 1 can be
formed even very large, if needed.
As opposed to what is shown in the appended Figs 1 to 6, the transfer
flow 2 and the projection screen 3 or projection volume 8 can be naturally
formed to extend to any direction, for example from down to up, or
vice versa, from one side to another, diagonally, or the like, by directing
the flow device 1 in a suitable manner.
Fig. 4 illustrates further an embodiment of the invention where the
laminar transfer flow 2 has been arranged, by a suitable design of the
structures of the flow device 1 and the supply means 5, to a curved
shape in order to form a curved projection screen 3. It is naturally obvious
that by the design of the structures of the flow device 1 and/or the
supply means 5, it is easy to provide also other forms of non-planar
flows. If necessary, the planar transfer flow 2 can be provided, using
the supply means 5 that is diagonally curved in view of the flowing
direction, with a curved projection screen 3 (in Fig. 4 the cross section
of the flow device 1 is oblong, and the supply means is curved), and it
is also possible to provide the curved transfer flow 2, using a suitable
supply means 5, with a planar projection screen 3.
it is obvious to an expert in the field that multiple flow devices 1 (and
possible suction devices 7) can be placed after each other in the flowing
direction, wherein projection screens of an arbitrary length can be
formed. In order to form different virtual spaces and rooms, a plurality
of apparatuses of the invention can be installed at suitable places of
the presentation space to form multiple projection screens that are
separate from each other.

The particles, or the like, that operate as scattering centres 4, can be
added to the transfer flow 2, for example using carrier gas or fluid
Since the molecules or atoms of gas or fluid operate as scattering
centres 4, they can be supplied in a corresponding manner to the
transfer flow 2, if necessary, by means of the carrier gas or fluid.
It is also possible that the scattering centres 4 are not formed until in
the actual transfer flow 2. Hence, the initial material or materials
needed in the formation of the scattering centres are supplied to the
transfer flow 2, where the initial material/materials react by forming
scattering centres 4. For example, vapour or a mixture of vapour and
air can condensate in the transfer flow 2 to water fog. The formation of
the scattering centres 4 can take place also through some other applicable
condensation, sublimation or chemical reaction.
The scattering centres 4 can be discharged to the transfer flow 2 from
nozzles of variable forms or, for example, from a perforated or split
tube, or also from another material-releasing organ or structure applicable
for the present purpose. The supply means 5 that spreads the
scattering centres 4 can constitute a part of the transfer flow 1 that produces
the transfer flow 2, or it can constitute a separate means at a
suitable position in the direction of the transfer flow 2, further away
from the flow device 1 and/or diagonally in view of the direction of flow,
at a suitable position of the transfer flow 2.
Using non-elastically light scattering material as the scattering centres
4, the wavelength of the radiation emitted by the scattering centres 4
differs from the wavelength of the radiation used for their activation and
has longer wavelength than illuminating radiation.
When using non-elastic scattering, the image formed on the projection
screen 3 s in principle monochromic, the colour being dependent on
the properties of the scattering centres 4 and the wavelength of light
transmitted by a projector 6 used for their activation. If the aim is to
form coloured images, scattering centres 4 that are composed of multiple
different materials and scatter light in different non-elastic manners
' must be used, a separate partial image being projected for each

scattering centre 4 using a suitably selected radiation of exciting wavelength
The non-elastically light-scattering scattering centres 4 can be for
example phosphorescent or fluorescent particles of solid material,
liquid drops, vapour or gas, and they can be illuminated by a suitable
laser projector or other projector 6 that sends ultraviolet light or visible
light. The light transmitted by the projector 6 now activates only desired
areas on the projection screen 3, wherein only these areas emit light
and form the image perceived by the observer. Thus, it is possible to
obtain images of arbitrary shape that can be observed in principle from
any possible angle because now also the actual images are transparent,
in addition to emission of light. In other words, the light emitted by
the scattering centres 4 activated by the projector 6 does not absorb to
a significant degree to other scattering centres 4, because the wavelength
of the emitted light differs from the light transmitted by the projector 6,
and is therefore not suitable for activation of the scattering
centres 4. Thus, using the method according to the invention, it is possible
in this embodiment to form images, videos, or the like, of objects,
people, and so forth, that appear to be floating in the air.
In projection screens 3 using elastic scattering and formed of fog, or
the like, the actual projection screen tends to become always visible, at
least to some extent, due to the normal lightning of the environment or
other diffused illumination directed to the projection screen or scatter-
ing/reflecting therefrom. In those embodiments of the invention that are
based on non-elastic scattering, the use of suitable scattering centre:*
4, for example gas molecules, makes it possible to arrange the
projection screen 3 in the normal prevailing light of the surrounding
area to be substantially transparent, in other words Invisible to the:
observer, because the light originating from the above-mentioned light
sources is not applicable for activating the scattering centres 4. This
makes it possible also to form multiple projection screens 3 adjacent to
each other in the direction of flow in a manner that the image formed in
a certain projection screen 3 is observed through adjacent projection
screens 3. By selecting the scattering centres 4 for each adjacent
projection screen 3 in a manner that different wavelengths and different

projectors/light sources 6 are used for their activation, it is possible to
form a different image for said different projection screens 3 and thus
to achieve a three-dimensional effect. By elaborating this above-
mentioned principle still further three-dimensional projection volumes
can be formed.
Figs. 5 and 6 illustrate the principle of the invention upon forming a
projection volume instead of a projection screen. A three-dimensional
projection volume 8 is formed of the scattering centres 4 that are discharged
from the supply means 5 and/or formed of source material/materials
discharged from said supply means 5. The scattering
centres 4 are allowed to the laminar transfer flow 2 in a plane that is
diagonal in view of the direction of said flow, only to desired locations
(from certain supply means 5) and only at desired moments of time.
This way a three-dimensional pattern, a projection volume 8, moving
along the transfer flow is obtained.
The resolution of the projection volume 8, and that of the three-dimensional
pattern obtained therewith, is dependent on the quantity, size
and the number density of the supply means, and the time control of
the feeding of the transfer flow 2 of the scattering centres 4. If the aim
is to produce a long unbroken pattern that is axial to the transfer flow, it
is not necessary to carry out exact time control to the supply means 5
{e.g. opening and closing).
The projection volume 8 can be formed either transparent or non-
transparent, wherein, particularly in the latter case, it is possible to
project a desired image or desired surface patterns on the outer surface
of the projection volume 8, if necessary. Nevertheless, it is not
necessary to use surface patterns. When the projection screen 8 is
transparent and when, e.g., using scattering centres 4 that are applicable
to non-elastic scattering, e.g., fluorescence, the scattering centres 4
can be activated, if so desired, on the whole volume area of the projection
volume 8, i.e., also inside the three-dimensional pattern formed by
the projection volume 8. Hence, an illuminating volume is formed.

Because the pattern formed by means of the projection volume 8
moves along the transfer flow 2, the projector 6 can, if necessary, be
arranged, to deflect the bearn/beams of light obtained from the light
source, to move along the pattern. Thus, for example a surface pattern
projected on the outer surface of said pattern can be made to move
along the pattern.
Scattering centres 4 are supplied to the transfer flow 2, preferably by
means of the supply means 5, such as, e.g., nozzles arranged to
matrix form and controlled by a data processing device, such as a
processor unit or computer.
By means of the projection volume 8, the forms of the three-dimensional
pattern to be created can be emphasized using illumination from
various directions, i.e., there can be more projectors 6, if needed,
arranged to illuminate the projection volume 8 from various directions.
It is obvious to anyone skilled in the art, that the projection screens 3 or
volumes 8 can be used both indoors and outdoors to substitute a traditional
screen or, e.g., to create preferably large or otherwise complicated
projection targets. An image or pattern can be projected from
different sides of the projection screen or projection volume, and the
projector/light source 6 used for producing the image or pattern does
not necessarily need to be perpendicular in view of the planar projection
screen. The image can, if necessary, be adjusted e.g. optically or
digitally using prior art techniques.
When using air or other harmless gas for forming the transfer flow 2,
and, e.g. dry dust or other risk-free materials as scattering centres 4, it
is possible to bring about walk-through projection screens 3 or projection
volumes 8.
Using the method and apparatus of the invention, projection targets of
arbitrary form can be created. Curved planes, different points of discontinuity,
and the like, can be readily brought about by means of the
invention.

The method and the apparatus according to the invention can be used
also for producing other surfaces and volumes than those needed for
imaging projection applications. The invention can be applied for
example for producing curtains or other visual obstructions or projection
screens needed for different illumination purposes.
It is, of course, obvious for anyone skilled in the art that by combining,
in different ways, the methods, modes of operation and device structures
presented above in connection with different embodiments of the
invention, it is possible to provide various embodiments of the invention
in accordance with the spirit of the invention.
It is, of course, obvious for anyone skilled in the art that the appended
drawings are oniy intended for illustration of the invention, and thus the
structures and components presented therein are not drawn to scale.

WE CLAIM :
1. A method for forming a non-solid projection screen or projection volume, in which method light
scattering / reflecting scattering centers are supplied to and / or produced to a substantially laminar
trans fer flow, said light scattering / reflecting scattering centers being transferred by said transfer flow,
wherein the scattering centers are supplied and / or formed to the transfer flow to the central / inner parts
thereof that remain laminar, away from the direct vicinity of the interface between the transfer flow and
the area surrounding thereof.
2. The method as claimed in claim 1, wherein the transfer flow is formed of gaseous substance.
3. The method as claimed in claim 1, wherein the transfer flow is formed of liquid substance.
4. Tie method as claimed in claim 1, wherein the scattering centers comprise light elastically scattering /
reflecting, solid, liquid or gaseous substance.

5. The method as claimed in claim 1, wherein the scattering centers comprise light non-elastically
scattering, solid, liquid or gaseous substance, which scattering centers are made to emit light by exciting
them by an electromagnetic radiation, that has higher energy compared to said emitting light.
6. The method as claimed in claim 5, wherein the scattering centers comprise fluorescent or
phosphorescent substance.
7. The method as claimed in claim 5, wherein the scattering centers are made to emit light by exciting
them with electromagnetic radiation having a higher energy compared to the emitting light.
8. The method as claimed in claim 1, wherein in the transfer flow the scattering centers are formed of
initial materials supplied to said transfer flow by condensation, sublimation and / or chemical reaction.
9. The method as claimed in claim 1, wherein the scattering centers are supplied and / or formed in a
transversal plane relative to the direction of the transfer flow, at multiple different locations of the
transfer flow.

10. The method as claimed in claim 1, wherein the scattering centers are supplied and / or formed to the
transfer flow in a method varying with time.
11. The method as claimed in claim 1, wherein the transfer flow and / or the scattering centers comprised
therein are collected by sucking the transfer flow and / or the scattering centers to a separate suction
device.
12. The method as claimed in claim 11, wherein the transfer flow and / or the scattering centers collected
by the suction device is used in the formation of the transfer flow and / or the projection screen and / or
the projection volume.
13. The method is claimed in claim 1, wherein multiple projection screens and / or projection volumes
are formed one after the other and/or side by side and / or one on top of the other to implement a broader
projection target and / or a virtual room / space and / or virtual pattern.
14. The method as claimed in claim 2, wherein the transfer flow is formed of air.
15. The method as claimed in claim 3, wherein the transfer flow is formed of water.
16. An apparatus adapted to provide a non-solid projection screen, projection volume, of light
scattering / reflecting scattering centers flowing along a transfer flow, comprising :
a flow device adapted to form a substantially laminar transfer flow, and one or more supplies
adapted to supply the scattering centers, and / or initial materials needed in the formation thereof, to the
transfer flow to central / inner parts thereof that remain laminar, away from a direct vicinity of interfaces
between the transfer flow and an area surrounding thereof.
17. The apparatus as claimed in claim 16, wherein the flow device is arranged to form the transfer flow
of gaseous subslance.
18. The apparatus as claimed in claim 16, wherein the flow device is arranged to form the transfer flow
of liquid substance.

19. The apparatus as claimed in claim 16, wherein the scattering centers comprise light elastically
scattering / reflecting, solid, liquid or gaseous substance.
20. The apparatus as claimed in claim 16, wherein the scattering centers comprise light non-elastically
scattering, solid, liquid or gaseous substance, which scattering centers are made to emit light by exciting
them with electromagnetic radiation, that has higher energy compared to said emitting light.
21. The apparatus as claimed in claim 20, wherein the scattering centers comprise flourescent or
phosphorescent substance.
22. The apparatus as claimed in claim 20, wherein the scattering centers are made to emit light by
exciting them with ultraviolet radiation.
23. The apparatus as claimed in claim 16, wherein one or multiple supplies are arranged to supply to the
transfer flow initial material / materials for forming the scattering centers in a transfer flow of said initial
material / materials through condensation, sublimation and / or chemical reaction.
24. The apparatus as claimed in claim 16, wherein the one or more supplies is / are arranged to supply
and / or form scattering centers in a plane transverse relative to the direction of the transfer flow, at
multiple different locations of the transfer flow.
25. The apparatus as claimed in claim 16, wherein the one or more supplies is / are arranged to supply
and / or form scattering centers to the transfer flow in a manner varying with time.
26. The apparatus, as claimed in claim 16, wherein there is provided a suction device for collecting the
transfer flow and / or the scattering centers comprised therein.
27. The apparatus as claimed in claim 26, having means for returning the transfer flow collected by the
suction device and / or the scattering centers back to the flow device for reuse.

28. The apparatus as claimed in claim 17, wherein the flow device is arranged to form the transfer flow
of air,
29. Trie apparatus as claimed in claim 18, wherein the flow device is arranged to form the transfer flow
of water.

A method for forming a non-solid projection screen (3) or projection
volume, in which method light scattering / reflecting scattering centers(4)
are supplied to and / or produced to a substantially laminar transfer flow (2),
said light scattering / reflecting scattering centers being transferred by said
transfer flow (2), wherein the scattering centers (4) are supplied and / or
formed to the transfer flow (2) to the central / inner parts thereof that remain
laminar, away from the direct vicinity of the interface between the transfer
flow (2) and the area surrounding thereof. An apparatus for implementing
the above method is also disclosed.

Documents:

876-KOLNP-2003-(02-01-2012)-FORM-27.pdf

876-kolnp-2003-granted-abstract.pdf

876-kolnp-2003-granted-claims.pdf

876-kolnp-2003-granted-correspondence.pdf

876-kolnp-2003-granted-description (complete).pdf

876-kolnp-2003-granted-drawings.pdf

876-kolnp-2003-granted-examination report.pdf

876-kolnp-2003-granted-form 1.pdf

876-kolnp-2003-granted-form 18.pdf

876-kolnp-2003-granted-form 2.pdf

876-kolnp-2003-granted-form 3.pdf

876-kolnp-2003-granted-form 5.pdf

876-kolnp-2003-granted-gpa.pdf

876-kolnp-2003-granted-reply to examination report.pdf

876-kolnp-2003-granted-specification.pdf


Patent Number 226794
Indian Patent Application Number 876/KOLNP/2003
PG Journal Number 52/2008
Publication Date 26-Dec-2008
Grant Date 24-Dec-2008
Date of Filing 09-Jul-2003
Name of Patentee RAKKOLAINEN ISMO
Applicant Address LUOLAKATU 4A 6, FIN-33710 TAMPERE
Inventors:
# Inventor's Name Inventor's Address
1 RAKKOLAINEN ISMO LUOLAKATU 4A 6, FIN-33710 TAMPERE
2 PALOVUORI KARRI LINNAINMAANRAITTI 18 A 5, FIN-33580 TAMPERE
PCT International Classification Number G03B 21/62
PCT International Application Number PCT/FI02/00026
PCT International Filing date 2002-01-15
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 20010085 2001-01-15 Finland