Compact lighting device, in particular for use in a dental lamp

[0001] The present invention relates to a compact lighting device, in particular for use in a dental lamp.

[0002] In many areas of activity where special precision is required for human or object interventions, it is useful to be able to use a dedicated light source that allows a clearer view of the object being worked on.

[0003] In particular, in the dental industry, it is necessary to illuminate the patient's mouth with a suitable lamp, generally mounted at the end of an articulated arm, in turn attached to a fixed structure, said lamp can be moved so as to direct the beam emitted by it lights to the desired point. In particular, the movable arm can be attached to the body of a more complex dental device, or otherwise directly to the wall. In some special cases, moreover, it is possible to make lighting devices of a suitably small size that can be worn directly by the dentist.

[0004] This type of lamp must meet a number of requirements that meet different needs.

[0005] The first requirement for dental treatment lamps is to focus the light beam, and this is due to the need to illuminate the patient's mouth in the best way possible without disturbing the eyes.

[0006] The second requirement for dental treatment lamps is to provide light radiation that has white light characteristics and more particularly than preferably has the following trichromaticity coordinates of four extreme points:

x = 0.310; y = 0.369; x = 0.316; y = 0.322; x = 0.414; y = 0.428; x = 0.396; y = 0.377;

with high color rendering index: Ra> 85.

[0007] In fact, light radiation cannot change the perception of the color of the patient's tooth surface by the dentist, as this would otherwise prevent the choice of the color of the possible dental prosthesis or joint cement to be used for any filling.

[0008] Furthermore, the infrared component of the light radiation emitted must be low, with a power density E <350 W / m² on the work surface to avoid heating the patient's body.

[0009] Not only this, but also the light radiation of dental lamps must simultaneously be free of ultraviolet components, i.e. radiation with wavelengths in the range of 10 nm - 280 nm (UV-C), 280 nm - 315 nm (UV-B), 315 - 400 nm (UV-A), which would not be healthy for the patient.

[0010] Finally, given that the last bonding cements are often obtained from polymer-based formulations containing curing compounds optically excited, generally by radiation in the blue band, light radiation must have low emission in the wavelength range from 400 nm up to 500 nm to avoid cement polymerization.

[0011] Another very important requirement today is to reduce the weight of the device. In fact, the design that creates the illuminating device must not restrain and / or obstruct the mobility of the dentist in any way, allowing him to direct the light beam where he considers it most appropriate, with minimal effort.

[0012] To achieve these goals, according to the state of the art, WO-A-02/06723, dental treatment lamps have been developed having a plurality of light sources, in particular a plurality of light sources with an LED (light-emitting diodes) in combination with optical instruments , such as, for example, the right number of shaped lenses, arranged between the light source and the surface of the object to be illuminated, hereinafter also referred to as the working surface, or otherwise a correspondingly curved reflecting surface located on the opposite side of the plurality of light sources relative to the working surface. In fact, if, on the one hand, by choosing the right materials, it is possible to obtain LED light sources that emit light radiation, having a well-defined frequency and wavelength, and as a result completely without radiation components in the infrared or ultraviolet band, respectively, on the other shaped lens sides or reflective surfaces are able to focus the light emitted by all of these LED light sources, in a well-defined area that contains a work surface.

[0013] Solutions similar to the solution of WO-A02 / 06723 are also described in WO-A-01/18445 and in US-A-5.722.762 which relate in particular to lighting devices that can be worn by a dentist like a pair of glasses , and which contain a plurality of light sources, wherein their emitted radiation is focused on the working surface by combination with appropriate optical instruments.

[0014] However, prior art solutions have a number of limitations that make their use not optimal.

[0015] In fact, none of the known solutions allows radiation emitted by light sources to be focused in an optimal way because there is always a certain percentage of emitted radiation that escapes optics which should ensure its concentration in a certain area.

[0016] Furthermore, the instruments currently used are quite massive.

In fact, since the position corresponding to the geometric center of gravity of the lamp is usually occupied by the light source device, rotation of the device about its horizontal axis of the geometric center of gravity is possible due to one or two pins which are transversely positioned outside the head.

[0018] These two pins are generally connected together through a small arch.

[0019] This configuration substantially inhibits and / or hinders the mobility of the dentist.

[0020] The general object of the present invention is to solve the above-mentioned disadvantages of the prior art in an extremely simple, economical and particularly functional manner.

[0021] Another object is to provide a compact lighting device capable of determining the shape and size of a light spot that can be obtained on a working surface.

[0022] Furthermore, according to the invention, a lighting device is provided that allows reducing both the total weight and the cooling requirements.

[0023] Furthermore, preferably, the device according to the invention has a lower mass than those commonly used.

[0024] In light of the above-mentioned purposes, in accordance with the present invention it has been decided to build a lighting device, in particular for use in a dental lamp, having the characteristics outlined in the appended claims.

[0025] The structural and functional characteristics of the present invention and its advantages compared to the state of the art will become clearer after studying the following description, referring to the attached drawings, which show the lighting device, in particular for use in a dental lamp, made according to innovative principles of the invention itself.

[0026] In the drawings:

- figure 1 shows a schematic perspective view of a preferred embodiment of the lighting device according to the present invention;

- figure 2 is a perspective view from above of the lighting device of figure 1;

- figure 3 shows a schematic perspective view of another embodiment of the lighting device according to the present invention; and

- figure 4 shows a schematic top view of the embodiment of figure 3 of the lighting device according to the present invention.

[0027] Referring to the drawings, the lighting device, indicated in its entirety by 10, and in the examples illustrated, in accordance with the present invention, comprises a pair of LEDs 11, each of which is associated with a primary collimation group 12, and a secondary mirror 13. Two LEDs 11 are also located on the same heat sink 14.

[0028] The lighting device is symmetrical about the axis, indicated by the letter Z, in the Cartesian reference system shown in figures 1 and 2.

[0029] The primary collimation group 12 is intended to focus the light radiation coming from two LEDs 11 into two corresponding cones, whose vertices converge in the first focus of the ellipsoid, and whose surfaces intersect the surface of said ellipsoid, designating two areas on which said secondary are arranged mirrors 13.

This optical system allows to determine the virtual image of the emission area of ​​each LED, located at the first focus of the ellipsoid. In this way, by using the optical properties of the ellipsoid, according to which the positioning of the point source of light in the first focus of the ellipsoid, causes its reflection to pass to the second focus, the optical system of the present invention while still containing a light source that does not is a point, allows the beam of light emitted by light sources to focus near the second focus.

[0030] Furthermore, in particular, each mirror 13 is made by bringing together a plurality of surfaces. Each of these surfaces displays a virtual image using the optical properties of the ellipsoid, even when the surface of the mirrors does not coincide perfectly with the surface of the ellipsoid. As a result, the projection of light beams from LEDs does not go exactly to the second focus, but the concentration of the beam is obtained in any case.

[0031] In this way, this scheme makes it possible to use two or more light sources located at a distance from each other, symmetrically with respect to the Z axis, and consequently at a distance from said Z axis, as if they were in reality situated on it. Thus, the Z axis is the optical axis of the lighting device 10, as a whole, coincides with that which would be the optical axis of a single mirror with an elliptical curvature used instead of the two secondary mirrors 13 of the lighting device 10 as shown in the preferred embodiment of the present invention.

[0032] By positioning the work plane between the first and second focal points of the ellipsoid, the light flow can be focused in a simple manner and a light image can be obtained according to the specific needs defined previously.

[0033] Another consequence of this arrangement of components of the lighting device 10 according to the present invention is that it allows focusing in relation to the mirror by moving a group consisting of two light sources 11 with an LED, and the respective primary collimation groups 12, along the Z axis, determining the shape and size of the light point on the work surface.

[0034] With reference in particular to figure 2, the light sources 11 with the LED are placed on the same heat sink 14, conveniently equipped with fins 15 to enlarge the scattering surface.

[0035] The material for the LEDs is suitably selected from materials that emit light radiation in the trichromatic reference coordinate range.

[0036] Finally, the lighting device 10 will be installed inside the box-shaped body, which may or may not include a screen in the area cut by the light beam emitted by the secondary mirrors 13.

[0037] The whole will then be installed on the free end of the movable arm, attached to the dental device or to the wall.

[0038] Furthermore, as can be seen in figures 3 and 4, the device 10 has a pin 18 suitable to allow the device to rotate about the horizontal axis 16 of the geometrical center of gravity.

[0039] Such a pin 18 is located in the geometrical center of gravity 21 of the device 10.

[0040] This arrangement is possible because, as can be seen in figure 4, in the lighting devices according to the invention, the position corresponding to the geometric center of gravity 21 of the structure is not occupied by the device for producing light beams.

[0041] Indeed, it can be seen in Figure 4 how the geometric center of gravity 21 is located outside the area defined by the circular line 20, which includes the part of the structure assigned to the device for generating light beams.

[0042] Furthermore, advantageously, with this arrangement it is possible to arrange two handles 19 for moving the device to a more inward position in relation to the prior art devices in which such handles are attached to the outside of the side of the structure.

[0043] Indeed, according to the invention, the two holders 19 are located at the rear, not the side of the mirrors 13, giving the structure significant compactness.

[0044] From what has been described above, with reference to the figures, it is clear how the compact lighting device according to the invention is particularly useful and advantageous. In this way the aim mentioned in the preamble of the description was achieved.

[0045] In conclusion, the compact lighting device according to the present invention has the following advantages with respect to prior art solutions.

[0046] First, the particular arrangement of the optical elements used allows the use of multiple light sources with a LED, whose radiation, however, is emitted as if it came from a single point source, where the advantage is that it is possible to obtain an optimal design of the reflecting surfaces.

[0047] On the other hand, by using two (or more) light sources, reflected by two (or more) reflecting elements, with the surface divided into facets, two (or more) optical beams fall on the working surface, coming from two (or more) separate axial directions, where the advantage is a significant reduction of shadows arising due to objects placed between the lighting device and the work surface.

[0048] An important feature of the illuminating device according to the invention is the possibility of axial focusing of the light sources relative to the secondary mirrors.

[0049] Finally, the selection of appropriate materials (in terms of light sources and / or filters introduced inside the optical group and / or on mirrors) allows obtaining light radiation with characteristics (trichromaticity coordinates, color rendering, absence of ultraviolet light, low blue content) required in the dental industry.

[0050] Of course, the shapes of the illuminating device according to the invention can be different from those shown, by way of non-limiting example, in the drawings, as can materials, which may also be different.

[0051] The protective scope of the invention is therefore defined in the appended claims.

FARO FABBRICA APPARECCHIATURE

RAZIONALI ODONTOIATRICHE SpA

Proxy:

32P24931PL00

EP 1 847 762 B1