Description

The present invention relates to an apparatus for generation of a volume of free air adapted for projection of holographic images.

Presently known is a technology enabling images to be reproduced in free air without requiring the presence of any "solid" support on which to project the images .

This type of projection that is called "holography" is very advantageous because it allows images to be reproduced where otherwise it would be very difficult to arrange a solid projection support, such as a plane surface, a monitor, etc.

In addition, this type of projection is very advantageous because it is absolutely non-invasive with respect to the environment wherein the images are intended to be projected.

Consequently, it is possible to state that the projection technology of holographic images of the present invention can be mainly put into practice in environments such as:

- the archaeological sites, where the holographic projection does not hinder the sight of the site itself and, where installation of solid projection supports is not possible, without damaging the site itself;

- the museum sites, where usually the spaces intended for image projections are separated from the exhibition spaces due to different lighting requirements; - the business sites, where it is possible to reproduce the products enlarged to life-size, without bulky supporting structures for the same being required.

From the above examples, the list of which is not exclusive but only given by way of example, it is apparent that the application fields of the technology of projecting holographic images of the present invention can be the most variable ones and that this technology enables images to be projected where otherwise it would not be possible to do it, due to space or light constraints or difficulties in installing conventional screens.

This holographic projection technology takes advantage of the optical properties of water, indices of reflection and refraction, for generating a circumscribed volume of an nebulized air-water mixture that will behave like a screen adapted for image proj ection .

Once this screen has been reproduced, which screen at all events can be defined as "virtual" as it is only made of an nebulized air-water mixture, it is possible to reproduce moving images thereon using the more or less traditional methods such as the video projection, laser projection, live shot projection with videocamera, etc.

The apparatus for the image projection is not the object of the present invention.

The presently known apparatuses generating these volumes of free air adapted for projection of holographic images comprise a blowing device fed with an nebulized air-water mixture generating, through an outlet orifice, a substantially flat laminar flow of this mixture in motion along an advancing direction. The difficulties that have to be faced for generating high-quality projections in free air relate to the difficulty in circumscribing and controlling the volumes of air-water mixture suitable for projection where, as mentioned above, these volumes are in motion and therefore subjected to the fluid dynamics laws. It is in fact a problem of the known art the fact that in distal positions from the flow source, the mixture does no longer move with a laminar motion adapted for holographic projection, but has a tendency to become turbulent thus impairing the quality of the projected image .

This problem is greatly increased when there is a requirement for projecting images of big height, such as the projection of a life-size person.

It is an aim of the present invention to provide an apparatus for generation of a volume of free air adapted for projection of holographic images which is able to solve the above mentioned drawbacks of the known art in a very simple, cheap and particularly functional manner.

Another aim of the invention is to provide an apparatus for generation of a volume of free air adapted for projection of holographic images capable of projecting high-quality images having big heights, such as projection of a life-size person, for example.

It is a further aim of the invention to provide an apparatus for generation of a volume of free air adapted for projection of holographic images in which the quality of the projected images is the same in the whole projection volume both distal and proximal to the source of the laminar flow of the nebulized air-water mixture . The above aims are achieved by providing an apparatus for generation of a volume of free air adapted for projection of holographic images, as set out in the appended claims.

The features and advantages of an apparatus for generation of a volume of free air adapted for projection of holographic images according to the present invention will be more apparent from the following description, given by way of non-limiting example, with reference to the accompanying drawing in which the only figure shows a diagrammatic view of an example embodiment of an apparatus for generation of a volume of free air adapted for projection of holographic images according to the present invention. With reference to this figure, an example of an apparatus for generation of a volume of free air adapted for projection of holographic images according to the present invention is identified with 10.

This apparatus comprises a blowing device 12 fed with an nebulized air-water mixture generating a substantially flat laminar flow of this mixture through an outlet orifice 18 and along an advancing direction .

In particular, according to _. the invention, the apparatus further comprises a device 13 for attracting the mixture forced into a laminar motion, which attracting device is placed downstream of the blowing device 12 relative to the mixture advancing direction. This attracting device 13 is provided with an inlet orifice 20 for the mixture such disposed as to face the outlet orifice 18 of the blowing device 12 where distance D between the two orifices, 18, 20 respectively, is of such a value that the mixture flow from the outlet orifice 18 to the inlet orifice 20 is substantially maintained of the laminar type.

In an embodiment, the attracting device 13 comprises a suction apparatus.

The presence of the suction apparatus, both causes motion of the mixture in a distal position from the outlet orifice 18 to be extended and, through suction of the mixture, ensures that said mixture will continue its laminar motion also on the last stretch of its travel. It is in fact known that this laminar motion is necessary for creation of a projection area that is reliable and not very sensitive to the external conditions .

As shown in the figure, the apparatus further comprises a chamber 11 for generating the nebulized air-water mixture which is connected to the blowing device 12 and provided with at least one opening for introduction of air into the chamber from the external environment.

According to the example shown, the generating chamber 11 comprises a water tank 21 and an ultrasound generator 17 associated with the water tank 21 for water nebulization in chamber 11.

Preferably the blowing device comprises a centrifugal fan 12 and its outlet orifice is in the form of a slit 18. In a like manner, the suction apparatus comprises a centrifugal aspirator 13 and its inlet orifice is in the form of a slit 20.

Preferably the apparatus further comprises a mixture recirculation duct 14 from the inlet orifice 20 to the outlet orifice 18.

According to two different examples, this recirculation duct 14 connects the suction device to the blowing device 12 or to the mixture generating chamber 11 connected to the blowing device 12.

According to a preferred embodiment, the generating- chamber 11 comprises a ionising device acting on the mixture for ion generation.

In a complementary manner, in this embodiment the attracting device 13 comprises an element electrically charged in the opposite way relative to such ions and acting as an attraction for the ions.

By way of example, said ions can be anions, i.e. negatively charged ions, and the electrically charged element being part of the attracting device can. therefore be positively charged.

By doing so, together with the presence of the suction, apparatus placed to the particular distance D and the slit-shaped conformation of the inlet 20 and outlet 18 orifices, the laminar motion of the mixture from the blowing device 12 to the attracting device 12 is further induced and controlled.

Note that said suction apparatus and electrically charged element can be used both combined together so as to advantageously add up the effects of same, and individually, in embodiments of simpler structure.

In order to prevent installation problems for the apparatus, the water tank can be of the type movable in rotation relative to the outlet orifice of the blowing device 12. In this way horizontal positioning- of the tank is always ensured, irrespective of the orientation of the outlet orifice 18.

In the same manner the inlet orifice 20 too can be oriented relative to the suction device 13. Should simultaneous accomplishment of different separate images disposed side by side be required, the apparatus can comprise an intermediate device which is, on one side, an attracting device and, on the ot ier side, a blowing device; this intermediate device is advantageously disposed at an intermediate position between the blowing device 12 and the attracting device 13.

In the last-mentioned case it will be necessary to suitably adjust the distance between the blowing 12 and attracting 13 devices and the intermediate cdevice, in order to maintain the mixture motion laminar between these separate stretches.

In an embodiment, to enable adjustment of distance D between the blowing device 12 and the attracting device 13, at least one of these devices can be movably supported on a perimetral frame-shaped frame-work.

In order to provide for an automatic adjustment of the distance and mutual position of the blowing device 12 and the attracting device 13, apparatus 10 can be equipped with one or more pressure sensors adapted to sense the mixture flow along the propagation thereof between the blowing device 12 and the attracting device 13.

Advantageously, said one or more pressure sensors are associated with a control unit in turn connected to a motor drive; the control unit, as a function of the data detected by said sensors, controls the motor drive for mutual positioning, in an automatic manner, of the blowing device 12 and the attracting devices 13 at the distance D between the orifices 18 and 20, so that the laminar motion of the mixture can be maintained over all this stretch.

Finally, in order to prevent formation of condensate on the outlet orifice 18 and inlet orifice 20, which condensate actually could nullify the laminar motion of the mixture between said orifices, the blowing device 12 and/or suction device 13 can comprise heating or cooling means acting on said orifices 18 and 20.

Thus it is possible to see that an apparatus for generation of a volume of free air adapted for projection of holographic images according to the present invention achieves the aims previously set out. In fact, the apparatus for generat ion of a volume of free air adapted for projection of holographic images according to the present invention is able to project high-quality images having big heights, such as projection of a life-size person, where the quality of the projected images is the same in the whole projection volume both distal and proximal to the source of the laminar flow of the nebulized air-water mixture .

This effect is ensured by the attracting device 13 facing the blowing device 12 at such a distance D that the mixture flow is maintained substantially of the laminar type in the whole projection volume.