WO2009104122A1

WO2009104122A1 - Projection device

Info

Publication number: WO2009104122A1
Application number: PCT/IB2009/050616
Authority: WO
Inventors: Reinhold Elferich; Horst Greiner
Original assignee: Philips Intellectual Property and Standards GmbH; Koninklijke Philips Electronics NV
Current assignee: Philips Intellectual Property and Standards GmbH; Koninklijke Philips NV
Priority date: 2008-02-21
Filing date: 2009-02-16
Publication date: 2009-08-27
Anticipated expiration: 2010-08-21
Also published as: TW200942861A

Abstract

The invention concerns a device for generation and projection of dynamic caustics, comprising a light source and a device for dynamic refraction of the incident light. The installation comprises an effects surface (2) made of a deformable material, and is provided with means to make a determined deformation.

Description

PROJECTION DEVICE

The invention concerns a device for generation and projection of dynamic caustics, comprising a light source and a device for dynamic refraction of the incident light.

To generate atmosphere images during big events, and also in stores, restaurants or during stage performances, so-called projection machines are used, which project dynamic and geometric light patterns on a surface. The aquatic reflection pattern is often used because of its calming down and relaxing effect, as we can see, for example, when the sun lights the bottom of a swimming pool, on walls that are located close to water, or also on a glass of water. Such a light pattern is characterized by caustic lines, which appear as the result of an intensity increase on the envelope of a large ray beam. Such a geometric light pattern is called caustic in optics. If a beam of parallel rays falls on the rounded interface of an optic medium, then the individual rays of the beam are deflected in a different way and then concentrate, in an amplified way, on some areas which become locally more lighted in relation to the average. To generate luminosity patterns reminding the light movements on water, rounded circular discs

(called "textured glass"), are used, rotated on the optical path, in front of a light source. The effects disc rotation generates luminosity pattern dynamics.

The disadvantage in known projectors is that the obtained luminosity patterns do not look much like the real model of the natural light movements on water. This is caused, amongst other reasons, by the fact that the patterns are essentially only moving - in accordance with the textured glass - on the screen.

The ambition of the invention is to remedy this disadvantage. The invention objective is to make a device for generating and projecting dynamic caustics that enable a more faithful representation of the natural light movements on water. This objective is completed, in accordance with the invention, because the installation comprises an effects surface made of a deformable material; which installation is provided with means to make a determined deformation.

The invention demonstrates a device for generating and projecting dynamic caustics that enable a more faithful representation of the natural light movements on water. Improving the invention, the effects surface is made as a deformable mirror. This way, we obtain a high light efficacy. In an alternative way, the effects surface may be also achieved as a transmitted light surface. However, this embodiment goes with light losses.

In a preferred embodiment, the effects surface is formed by a dielectric elastomer actuator (DEA). The dielectric elastomers are adaptive material systems able to generate high dilatations. They belong to the electroactive polymers (EAP) group. Using their simple working principle, the dielectric elastomer actuators (DEA) directly convert the electrical energy in mechanical work. The dielectric elastomers have a high elastic energetic density. A DEA is, in principle, a soft electrostatic capacitor. A passive elastomer sheet is jammed between two soft electrodes. When an electrical voltage is applied, the two opposite electrodes attract each other because of the electrostatic pressure. The incompressible elastomer sheet is compressed in the thickness direction and dilated in the lateral direction. During a short-circuiting of the circuit, the elastomer sheet returns to its original state. Dielectric elastomer actuators of this type enable a targeted dynamic bending of the effects surface. To obtain the wanted light effects, that can be formed, in the effects surface, a number of changing "valleys" and "hills", which look like a lightly rippled water surface.

Improving the invention, the DEA comprises at least two layers. By making piles of several DEA layers, the maximum deflection level that can be obtained can be increased.

In another embodiment, the DEA electrodes are made of graphite or metal powder. In this case, the material is flexible and has a good electrical conductibility, meaning that it is deformable and that it is able to be structured and put in contact. In an embodiment of the invention, the electrode powder is applied on the elastomer layers according to a screen-printing method. This way, various electrode patterns can be made, which enables to obtain a determined deflection of the effects surface when a voltage is applied.

The light source is achieved, in an advantageous way, so as to emit a parallel light on the effects surface. In this manner, a good reproduction of the water movements' natural effects can be achieved.

Other improvements and embodiments of the invention are indicated in the other sub-claims. An example of embodiment of the invention is shown on the characters and will be described in details in the following. The characters show:

Fig. 1 : The schematic representation of a device for generation and projection of dynamic caustics;

Fig. 2: The schematic representation of a device for generation and projection of dynamic caustics in another embodiment; Fig. 3: The schematic representation of an EAP-arrangement with a dielectric layer in transversal section a) without applied voltages Vl -V5 b) with applied voltages V 1 ,V3 , V5 (V2, V4 = 0)

Fig. 4: The schematic representation of an EAP-arrangement with three dielectric layers in transversal section;

Fig. 5: The schematic representation of an EAP-arrangement with a non- plane dielectric layer, deformed in transversal section a) without applied voltages Vl -V4 b) with applied voltages Vl -V4; Fig. 6: The schematic representation of a mechanical device for generation and projection of dynamic caustics in an embodiment with a liquid located in a tank containing actuators, and

Fig. 7: The schematic representation of a mechanical device for generation and projection of dynamic caustics a) in the beginning position b) mechanically deformed by rods. The device chosen as example of embodiment for generation and projection of dynamic caustics is essentially constituted of a base 1, on which a dielectric elastomer actuator 2 is set, and of a light source 3 to emit a parallel light; which light source lights up the dielectric elastomer actuator 2 surface. Base 1 is achieved in the example of embodiment according to figure 1, as a flat sheet provided with not- represented connexions for voltage supply.

The dielectric elastomer actuator 2 forms an effects surface. In the example of embodiment, it is a DEA-multilayer and comprises four dielectric elastomer layers 21. An electrode layer 22 is set, each time, between the elastomer layers 21, the electrode layer being made of a graphite powder layer in the example of embodiment. In the state of art, we know alternative methods for providing the elastomer layers 21 with electrodes. The surface, oriented toward base 1, of the elastomer actuator 2, is provided with a reflection layer 23. The DEA 2 is bounded with base 1 so that the electrode layers 22 are bound to the - not-represented - voltage connexions of base 1. The voltage supply control is done through a

- not-shown - control module, which is connected to a - not-shown - computing unit. Thanks to this computing unit, any mathematically definable surface (while staying in the physical limits area of the dielectric elastomer) can be represented on the DEA-effects surface 2.

In the example of embodiment according to figure 1 , the light source 3 is shifted in relation to the DEA-effects surface 2. The light source 3 is achieved as to emit parallel light on the DEA-effects surface 2. By modifying in a targeted way the DEA- effects surface 2 area, can be modified in a targeted way the reflection of the light emitted by the light source 3. On the figures, we have represented, for example, the optical path 31 of the DEA-effects surface 2 without applying a voltage, as a continuous line, and the optical path 32 when a voltage is applied to the DEA 2.

In the example of embodiment according to figure 2, base 1 is achieved in a homogeneous way and curved in a parabolic way, so that the applied DEA-effects surface 2 has also a curved basic surface. The light source 3 is set, in the example of embodiment according to figure 2, in the middle, in front of the DEA-effects surface 2. The parabolic achievement of the DEA-effects surface 2 enables a compact construction. The optical path 31 of light source 3 from the DEA-effects surface 2 is once again indicated by continuous lines, and the optical path 32, from the DEA-effects surface 2, with an applied voltage, is represented by dotted lines. The DEA-effects surface 2 may either receive a reflective coating or else, in the case of an appropriated dielectric, be created very transparent, for example with silicon and appropriated electrodes. The effects surface may thus be used with the transmitted light or the incident light. The deformation amplitude of the effects surface 2 is around the tenth of millimetre; in the case of reflective devices the necessary deformation to obtain the wanted "light movements on water" effect is in principle lower than in the case of transmitted light arrangement.

Fig. 3 shows an EAP-arrangement with a dielectric layer 21 between the electrodes 22a, 22b on a base 1 in transversal section. The electrodes 22a, 22b are constituted of several electrodes, which may be controlled individually. For example, some individual dots may be activated in a matrix arrangement by applying a voltage on the corresponding electrodes (these are the electrodes that correspond to the individual dots). Figure 3b) represents the deformation resulting from the effects surface 2 after applying a voltage Vl, V3 and V5 on the corresponding connexion terminal - represented in a circular way. To minimize the controlling complexity, we can also group together some groups of electrodes spread over the entire effects surface 2, which enables to activate them at the same time, and to obtain the wanted characteristic deformations of the effects surfaces 2.

Fig. 4 shows a similar arrangement. When we modified the arrangement on figure 3, one over another several deformable dielectric layers 21 are piled up, whose electrodes may be connected in parallel (not represented). The advantage of this last disposition is that we can obtain a more important deformation while applying the same voltage.

Fig. 5 represents another modification of the arrangements described above. Here, base 1 is made as a planar surface, but as a surface deformed in a number of ways. In a no voltage state, there is already a corresponding deformation (to be compared with figure 15a)) of the effects surface. In the activated state, meaning while applying a voltage, a form in opposite direction is achieved, as shown on figure 5b). This way, we can obtain a higher local resolution of the deformation, while using the same electrodes density.

In the example of embodiment according to figure 6, the effects surface 2 is formed by a liquid, for example water, filling a tank 25. The tank 25 is provided with actuators 26 that enable the displacement. Movements of the tank 25, initiated by the actuators 26, are transmitted to the liquid 24, which causes waves generation on the effects surface 2. In an alternative way, the liquid may be set in motion not only indirectly (through the tank), but also directly, for example by actuators set in the liquid, or by flowing. The effects surface made this way may be used in the transmitted light or in the incident light (total reflection). The light source may also be set in the liquid tank. In this manner, we can obtain, if need, be, a necessary cooling of the light source. The interior walls of the tank are preferably created reflective . The tank shape is created, for example, as a goblet or a funnel shape, and is used to improve and control the projection, respectively the projection size, in cooperation with the light source position.

The effects surface 2 deformation may be built, in an alternative way, mechanically. Fig. 7 shows, for example, the representation of an effects surface 2 under the form of an elastic layer, which has a reflexive surface that is deformable by a rods array 27, which may be displaced in a perpendicular way. Figure 7a) shows the deformation of the effects surface 2 after the rods 27 displacement in direction x (xl, x2, x3, x4>0).

As a light source 3, for example, LED lamps, laser lamps, discharge lamps or light bulbs can be used. Preferably white light is chosen. In a EAP transmitted light device, phosphors for wavelength conversion can be integrated into the elastomer, so as to convert, for example, blue radiation into white radiation. Preferably a lighting system that emits parallel light (see figure 1) is used. In principle, as a light source 3 an emitter that is essentially dot-shaped (compare figure 2) can be used.

In the subsequent optical path - from the effects surface 2 - a lenses system can be set to control the projection size. Conversely to the usual image projectors, there is no focalisation in the usual meaning. When the distance between the dot-shaped light source and the effects surface 3 is changed, we see a modification of the projected caustics extension and shape (or distortion level), which caustics are however sharply mapped on large areas. On the other hand, we need here to adapt the deformation average amplitude on the effect surface 2.

Another possibility is the setting of a screen, for example as a diffusing panel - or depolished glass in the optical path behind the effects surface, as a device component, on which screen the caustics are mapped - now in an autoluminescent way. These caustics may be directly watched or reproduced using appropriated means, such as, for example, a slide projector. This possibility is generally less luminous than the one said above. As a summary, in particular three possibilities to control the projection size exist: the homogenous deformation of the effects surface 2 (meaning of its base 1) (extra parabolic or spherical), the modification of the distance from the light source 3 and the effects surface 2 (except in the case of a light source with parallel light), and the use of a lenses system. The advantage of the first two possibilities lies in their compact shape. A distinctive feature of the first one is that such a deformation, meaning the base 1 deformation, may be obtained because of a DEA. Base 1 itself is a DEA that causes the homogenous deformation, because of an appropriated electrodes pattern and to the said electrodes control.

Claims

CLAIMS:

1. Device for generation and projection of dynamic caustics, comprising a light source and a device for dynamic refraction of the incident light, characterized in that the installation comprises an effects surface made of a deformable material; which installation is provided with means to make a determined deformation.

2. Device according to claim 1, characterized in that the effects surface (2) is made as a deformable mirror.

3. Device according to claim 1 or 2, characterized in that the effects surface (2) is formed by a dielectric elastomer actuator (DEA).

4. Device according to claim 3, characterized in that the DEA comprises, at least, two layers (21).

5. Device according to one of the claims 3 and 4, characterized in that means to convert the transmitted light wavelength are integrated into the DEA.

6. Device according to claim 5, characterized in that the means to convert the wavelength comprise phosphors.

7. Device according to one of the claims 3 and 4, characterized in that the DEA is set on the base 1, which is made in a planar or lightly rounded way.

8. Device according to one of the claims 1 or 2, characterized in that the effects surface (2) is formed by a liquid (24) located in a tank (25), the tank being able to be displaced by at least one actuator (26).

9. Device according to one of the claims 1 or 2, characterized in that the means used to deform in a determined way the effects surface (2) comprise mobile rods (27).

10. Device according to one of the claims above, characterized in that the light source (3) is created as to emit parallel light on the effects surface (2).