WO2008120255A1

WO2008120255A1 - Lighting device

Info

Publication number: WO2008120255A1
Application number: PCT/IT2007/000251
Authority: WO
Inventors: Luca Bergo
Original assignee: Fontanaarte S.P.A.
Priority date: 2007-04-03
Filing date: 2007-04-03
Publication date: 2008-10-09

Abstract

A lighting device comprises at least one light source (2) and a body (3) that is respectively movable between a first position at which it conceals the light source (2) that is generally turned off to the sight of an observer, and a second position at which it makes visible the light source (2) that is turned on. The device further comprises actuating means (4) associated with said movable body (3) and including at least one shape memory actuator (5) that is selectively deformable between a first geometric condition corresponding to the first position of the movable body (3) in which the light radiation is absent, and a second geometric condition corresponding to the second position of the movable body (3) in which the light radiation is present.

Description

LIGHTING DEVICE

D e s c r i p t i o n

The present invention relates to a lighting device. In particular, the present invention concerns a disappearing or concealable lighting device.

Different light devices are known that enable the light source to be concealed when no lighting is reguired and vice versa to be made visible when necessary.

Generally, similar lighting devices are embedded in the wall, being devoid of any externally visible support and concealed by a panel enclosing the lamp in a space in the wall when said lamp is turned off. Usually the panel is painted using the same colour as the surrounding wall to better camouflage the position of the device.

The lighting device is therefore almost invisible when it is turned off. After the lighting device is turned on, the panel slowly opens and diffuses the light in the surrounding atmosphere. After turning off and cooling of the lamps, the panel automatically closes.

Such an apparatus can be embedded in the wall, the ceiling or also the floor, at regions that cannot be trodden on, such as in rooms for exhibitions, museum rooms or fairs for example, or in passage regions, corridors, flights of stairs or access areas for example.

In the devices of the known art, movement of the panel, generally of the rotational type, is operated by a motor. The panel usually rotates around a hinge axis coincident with a side of the panel and an outer edge of the light-containing space.

Therefore two power supply sources are present, one for the lights and one for the motor moving the panel, which has drawbacks due for example to a greater structure complexity and -a greater bulkiness of the device itself. ' ■^■

The presence of a motor inevitably involves frequent servicing and when a motor is embedded in a wall servicing surely is rather difficult and also expensive.

Accordingly, it is an aim of the present invention to make a concealable lighting device using a single power supply system both for turning the lights on and moving the panel.

It is a further aim of the present invention ^'to propose a lighting device of easy assembly and capable of reducing the bulkiness in the wall.

Finally, it is another aim of the present invention to provide a lighting device that is more reliable than the devices of the known art, involves less servicing operations and has reduced manufacturing and operating costs .

The technical task mentioned and the aims specified are substantially achieved by a lighting device comprising the technical features set out in one or more of the appended claims . Further features and advantages of the present invention will become more apparent from the description given by way of non-limiting example of a preferred but not exclusive embodiment of a lighting device, as shown in the accompanying drawings, in which:

- Fig. 1 represents a perspective view of a lighting device in accordance with the present invention;

- Fig. 2 is a side view of the lighting device in Fig. 1, in a first configuration;

- Fig. 3 is a side view of the lighting device in Fig. 1, in a second configuration.

With reference to the drawings, a lighting^' device in accordance with the present invention has been generally denoted with reference numeral 1.

The lighting device 1 is of the disappearing type, i.e. it is embedded in the walls, the ceiling or the floor, at regions that cannot be trodden on, in rooms and the like, or also in walls placed outdoors.

The lighting device 1 comprises at least one light source 2 alternately concealed or made visible by a movable body 3.

Body 3 is movable between a first position at which the light source 2 is preferably turned off and a second position at which the light source 2 is turned on.

Body 3 is a panel moving between the first and second positions according to a relative movement, selection of which can be done during the planning step according to the different requirements; for instance, movement can take place by sliding along a plane or by rotation around a hinge axis or by a rotational-translational motion, such as a swinging movement.

The lighting device 1 further comprises actuating means 4 associated with said movable body 3 to drive said body 3 between the first and second positions.

The actuating means 4 comprises at least one shape memory actuator 5, i.e. an actuator that is made of a shape memory alloy (SMA)

Shape memory alloys are known metal materials having the ability to restore their starting configuration if deformed and submitted to suitable heat treatment. In particular, SMA undergo a crystalline phase transformation when they are brought from their stiffer high-temperature configuration to the lower energy and temperature configuration. This transformation is the main cause of the particular qualities of these alloys. When an SMA is brought to a low temperature it has a low yield point and can be easily deformed; following heating, the alloy is disposed according to another crystalline structure and therefore takes the starting shape and configuration again. The temperature at which the alloy "remembers" its original shape can be modified by varying the composition or adopting suitable heat treatments.

Generally, nickel-titanium alloys are used or, alternatively, copper-based alloys, such as copper- zinc-aluminium or copper-aluminium-nickel alloys.

Preferably, a nickel-titanium alloy consisting in particular of 50% nickel and 50% titanium is used. In accordance with the particular feature of the shape memory alloys, actuator 5 is therefore selectively deformable between a first and a second geometric configurations .

In particular, actuator 5 takes the first geometric configuration when the movable body 3 is in its first position, at which the light source 2 is turned off, and takes the second geometric configuration when the movable body 3 is in the second position, at which the light source is turned on.

Advantageously, the shape memory actuator 5 is an elastic element.

Actuator 5 is thermally deformable between a first and a second geometric conditions, following temperature variation.

In the configuration shown, the shape memory actuator 5 is electrically deformable, following passage of electric current through the actuator 5 itself.

In fact, advantageously, actuator 5 is connected to a power supply source 6 in such a manner that passage of electric current produces heating of actuator 5 by Joule effect.

The same power supply source 6 to which actuator 5 is connected also feeds the light source 2. In this way the lighting device 1 has a smaller bulkiness and weight .

The actuating means 4 comprises a linkage 7 connecting the movable body 3 to the shape memory actuator to displace body 3 from the first to the second position.

The actuating means 4 further comprises an elastic return element 8 co-operating with the shape memory actuator 5 to move the movable body 3, in particular to displace it from the second to the first position.

Advantageously, the lighting device 1 further comprises a stiffening frame 9 defining a hollow holding space 10.

Alternatively, device 1 may also be housed in a niche formed in a wall and defining the hollow holding space, without the aid of any stiffening frame.

In both cases, when the lighting device 1 is turned off, the light source 2 is fully housed within the hollow holding space 10. When the light is turned on, on the contrary, the light source 2 is at least partly at the outside of the hollow holding space 10. Body 3 is movable relative to said hollow space 10.

In particular, in the first configuration at which the light source 2 is turned off, the movable body 3 closes the hollow space 10, concealing the light source 2 to the sight of an observer, as shown in Fig. 2. Vice versa, in the second configuration, at which the light source 2 is turned on, body 3 opens the hollow space 10 making the light source 2 visible from the outside, as shown in Fig. 3.

In the preferred configuration shown in Fig. 1 it is provided that body 3 be a panel articulated along a hinge axis 11 coincident with one side 3a of the panel and one peripheral edge 10a of the holding space 10. In a preferred configuration shown in the drawings, the light source 2 comprises at least two lamps 2a.

Still in accordance with the preferred configuration, the light source 2 is mounted on a surface 3b of the movable body 3 facing the inside of the holding space 10 when the movable body 3 is in the first position so as to close said hollow space 10. The light source 2 is therefore movable together with body 3 with respect to the hollow space 10. The inclination of the light beam is therefore determined by the position of the movable body 3. Other adjustment systems capable of rotating the light source 2 so as to better direct the light beam where required may also be provided.

In an alternative configuration not shown, the light source 2 is provided to be directly mounted within the holding space 10. In combination with this alternative configuration, a system for moving the light source and bring it at least partly to the outside of the holding space when said light is turned on may be provided.

In more detail as regards the actuating means 4, and referring particularly to the preferred configuration shown in Fig. 1, linkage 7 comprises at least one bar 12 having one elbow 13 dividing the bar 12 into a first portion 12a and a second portion 12b that are inclined to each other and preferably have different lengths.

In particular, the first portion 12a preferably having a greater length than the second portion 12b, is stably secured to surface 3b of the movable body 3 that in the closed position faces the inside of the holding space 10. To balance the weight of the movable body 3, it is preferable for the first portion 12a to be secured to body 3 at a central region thereof or along an axis of symmetry of the body 3 itself, as shown in Fig. 1.

The elbow 13 of bar 12 is pivotally mounted on a hinge point 14 of frame 9, inside the hollow space 10, located close to the hinge axis 11. Bar 12 is such oriented that the second portion 12b thereof is inside the hollow space 10 and faces the centre of said space 10.

According to this configuration, frame 9 in the vicinity of the hinge point 14 of elbow 13, has a slit 9a to enable passage of the second portion 12b of bar 12 when the movable body 3 is in the first position, i.e. when it closes the holding space 10, as shown in Fig. 2.

In this position, the second portion 12b of bar 12 is external to the holding space 10.

The free end 15 of the second portion 12b of bar 12 is secured to the shape memory actuator 5. Actuator 5 in turn is connected to frame 9, at the inside of the holding space 10.

The elastic return element 8, co-operating with actuator 5, is connected at a first end 8a thereof to body 3 and at a second end 8b to a point of frame 9 internal to the holding space 10. When body 3 is in the first position, i.e. when the hollow space 10 is closed, the elastic return element 8 has a smaller extension than the extension it takes when body 3 is in the second position, i.e. when the hollow space 10 is open. In the last-mentioned configuration the elastic return element 8 is extended. Preferably, both the elastic element forming actuator 5 and the elastic return element 8 are springs with a different modulus of elasticity.

In particular, in the first geometric configuration, occurring at a first temperature Ti, the shape memory spring or in an equivalent manner actuator 5, is extended. On the contrary, in the second geometric configuration occurring at a second temperature T₂ higher than temperature Ti, the shape memory spring or in an equivalent manner actuator 5, is compressed. Typically temperature T₁ is a value close to the room temperature, therefore not exceeding 35⁰C, while temperature T₂ is higher than 80 °C and at all events depends on the deformation that is wished to be obtained.

In use, when the light source 2 is turned off, body 3 is in the first position, see Fig. 2, i.e. the holding space is fully closed, so that the lamp cannot be seen by an observer present in the room.

Since the light source 2 is turned off, through actuator 5 there is no circulation of electric current and therefore the whole device 1 is at temperature Ti. At a low temperature the shape memory actuator 5, therefore the SMA spring, has a low yield point so that it is easily deformable; in particular the SMA spring is extended in the first geometric configuration and does not exert any force on bar 12 connected to body 3. Under this situation, the elastic force of the return element 8 is greater than that of the shape memory actuator and therefore the return element 8 is able to exert a traction on body 3 to keep it steady in the first closed position of the hollow space 10. When the light source 2 is turned on, the electric current also flows through actuator 5 that becomes heated in few seconds and progressively reaches temperature T₂.

As the shape memory actuator 5 is heated, it reaches the second geometric configuration, takes the original undeformed configuration again and increases its elastic force,, at a certain point overcoming that of the return element 8.

In particular, due to heating, actuator 5 becomes shorter and consequently exerts a tractive force on bar 12 that, through rotation around the hinge point 14, pushes body 3 downwards, until bringing it to the second open position of the hollow space 10. As far as temperature keeps high and higher than temperature T₂, actuator 5, through the action of bar 12, keeps body 3 steady in the second open configuration of the hollow space. The elastic return element 8 extends and follows the movement of body 3.

During this transformation, forces of important amount stored and released by the material can be involved and they allow the panel on which the lamps are mounted to be shifted.

Rotation of body 3 around the hinge axis 11 causes surface 3b on which the light source 2 -is mounted to face the outside of the hollow space 10, making the light source 2 visible and enabling the light beam to be directed where required to illuminate the surrounding atmosphere.

When, lastly, the light source is turned off, there is a transient of the duration of some tens of seconds, during which temperature goes back to the value of Ti. During cooling, the yield point of the shape memory actuator 5 decreases, actuator 5 is extended again and progressively goes back to the first geometric configuration, its elastic tractive force losing intensity. On decreasing of the tractive force of actuator 5, the tractive force of the elastic return element 8 starts prevailing again, until full closure of the hollow space 10.

Using springs with an appropriate modulus of elasticity, the opening angle of the panel can be adjusted, until causing its rotation even through 90° around the hinge axis, on passing from the first to the second positions, so that different openings and different orientations of the light beam can be obtained.

The visible surface 3c of body 3 can be painted in the same colour as the surrounding wall or decorated at will so as to further camouflage the position of device

1.

The present invention achieves the intended purposes.

In fact, as said, the power supply source is only one and it governs both turning on of the light source 2 and operation of the actuating means 4. In this way bulkiness of device 1 is very reduced, as well as weight .

It is however emphasised that in case of particular applications or with some light sources, it is at all events possible to use a dual power supply source without however impairing the possibility of reducing the bulkiness.

The reliability of a system in which the behaviour of a material is based on temperature variations is surely greater than that obtained with use of a device driven by a motor.

A possible servicing in fact would only involve a mere replacement of a spring, which operation is very simple and has very reduced costs.

There are also lower consumptions since with the same electric current two user bases are simultaneously powered.

In addition the device is quite noiseless.

Finally, similar devices suitably equipped with passage sensors can be efficiently applied in those places where lighting can be timed.

Claims

C L A I M S

1. A lighting device comprising:

- at least one light source (2); - a body (3) movable between at least one first position at which the light source (2) is preferably- turned off and the movable body (3) substantially covers said light source (2) , and a second position at which the light source (2) is turned on and the movable body (3) enables light radiation;

- actuating means (4) associated with said movable body (3) to shift it between said first and second positions ; characterised in that said actuating means (4) comprises at least one shape memory actuator (5) which is selectively deformable between a first geometric configuration corresponding to said first position of the movable body (3) in which the movable body (3) substantially covers the light source (2), and a second geometric condition corresponding to said second position of the movable body (3) in which the light source (2) is turned on.

2. A device as claimed in claim 1, wherein said actuating means (4) comprises at least one linkage (7) connecting said movable body (3) to said shape memory actuator (5), to shift said movable body (3) between the first and second positions.

3. A device as claimed in claim 2, wherein said shape memory actuator (5) is an elastic element made of a shape memory alloy.

4. A device as claimed in claim 3 wherein said elastic element is a spring.

5. A device as claimed in anyone of the preceding claims, wherein said shape memory actuator (5) is thermally deformat)Ie between the first and second geometric conditions, following a temperature variation.

6. A device as claimed in anyone of the preceding claims, wherein said shape memory actuator (5) is electrically deformable between the first and second geometric conditions, following passage of electric current through the actuator (5) itself.

7. A device as claimed in claim 6, wherein said shape memory actuator (5) is electrically connected to a power supply source (6) in such a manner that said actuator (5) changes its geometric condition when heated by Joule effect on passage of electric current.

8. A device as claimed in claim 7 wherein said power supply source (6) is also connected to said light source (2) .

9. A device as claimed in claim 4 wherein, in the first geometric condition, at a first temperature (Ti) , said shape memory actuator (5) takes an extended conformation, and in the second geometric condition, at a second temperature (T₂) higher than the first temperature (Ti) , said actuator (5) takes a compressed conformation .

10. A device as claimed in anyone of the preceding claims, wherein said shape memory actuator is preferably made of a nickel-titanium alloy.

11. A device as claimed in anyone of the preceding claims, comprising a stiffening frame (9) defining a hollow holding space (10); said light source (2), when turned off, being fully housed within the holding space (10) .

12. A device as ^' claimed in claim 11, wherein said light source (2) is mounted on a surface (3b) of said movable body (3) ; said surface (3b) facing the inside of said holding space (10) when the movable body (3) is in the

10 first position, so as to close said holding space (10).

_':.

13. A device as claimed in claim 12, wherein the light source (2), in a condition at which radiation is present, is at least partly external to said holding

15 space (10) .

14. A device as claimed in claim 11, wherein said actuating means (4) further comprises at least one elastic return element (8) co-operating with said shape

20 memory actuator, to shift said movable body (3) .

15. A device as claimed in claim 14, wherein said elastic return element (8) connects the movable body (3) to a point internal to said holding space (10) .

25

16. A device as claimed in claim 14, wherein in a condition of turned-off light source the shape memory actuator (5) is extended while the elastic return element (8) is shortened so as to maintain the movable

30 body (3) steady in the first position, and in a condition of turned-on light source (2) the shape memory actuator (5) becomes shorter and pulls the linkage (7) in such a manner as to bring and maintain the movable body (3) to the second position while the

35 elastic return element (8) is extended following the movement of the movable body (3) .

17. A device as claimed in anyone of claims 14 to 16, wherein said elastic return element (8) is a spring.

18. A device as claimed in claim 11, wherein said movable body (3) is a panel that is movable relative to said hollow space.

19. A device as claimed in claim 18 wherein said panel can be rotated relative to the frame (9) around a hinge axis (11); said axis (11) being for example coincident with one side (3a) of the panel and one peripheral edge

(10a) of said hollow holding space (10).