Patent Publication Number: US-2006002135-A1

Title: Dental lamp particularly for medical and dental surgeries

Description:
The present invention relates to a dental lamp particularly for medical and dental surgeries.  
     BACKGROUND OF THE INVENTION  
      In dental surgeries it is necessary to supplement the diffuse ambient light with a beam of light that is localized on the part of the patient to be analyzed (in this case, the mouth).  
      The light source required to provide this type of localized light is therefore a orientable lamp, which is generally mounted on a movable arm (so as to be able to direct the light beam exactly in the chosen point) with an intensity, frequency and color temperature of the emitted beam that are clearly defined by standard parameters.  
      Currently applicable standards prescribe conditions regarding the light spot generated by the lamp on a surface that is at a distance of 700 mm (reference plane) from the emission point. The luminous intensity must be comprised between 75% and 100% of the maximum luminous intensity within a circle having a diameter of 50 mm that is centered in the center of the spot (which is elliptical). In the region comprised between said circle and the perimeter of the elliptical spot, the intensity must be comprised between 50% and 75% of the maximum value. At a distance of 60 mm from the center of the elliptical spot, the intensity must be lower than 1200 lux.  
      The light beam emitted by a halogen lamp can be adjusted by varying the voltage or by adjusting the position of the reflective screen.  
      The light beam that reaches said spot from the lamp body must be such that the shadow produced by a metallic disk having a diameter of 20 mm and a thickness of 1 mm placed at 50 mm from the reference plane is a dark spot with a maximum diameter of 12 mm.  
      The frequency and the color temperature are closely mutually correlated parameters, since a warm light, which corresponds to lower frequency values (with a lower limit constituted by the infrared), is associated with lower temperatures than a cold light, which corresponds to higher frequency values (with the ultraviolet as an upper limit).  
      The dental surgeon must recognize unequivocally the color of a tooth for which a prosthesis is to be prepared (or which he must reconstruct in some way); the light with which the mouth is lit significantly alters color perception, and therefore the standards require the light to be white with a color temperature that the standards specify as comprised between 3600 K and 6500 K (with a preferable intermediate band comprised between 5000 and 5500 K).  
      Usually, the light sources used inside lamps for the dental sector of this type are halogen lamps, which are able to provide good beam intensity and, if appropriately directed by a suitable parabolic reflector, allow to obtain a highly concentrated illuminated portion (according to the requirements of the standards).  
      It should be noted that the color temperature of the light beam emitted by a halogen lamp generally depends in a strict sense on the hours of operation and on the type of treatment performed on the parabolic reflector used to direct said beam.  
      Halogen lamps generate a large amount of heat in all directions: part of this heat entails rapid overheating of the lamp body, and part of the remaining heat is emitted in the direction of the light beam.  
      Overheating of the lamp body is extremely negative for correct operation, since the components age precociously due to the thermal stress and further work in conditions that are far from the ones that provide maximum efficiency. In order to obviate this drawback, a ventilation element is usually installed inside the lamp body in order to remove the maximum possible amount of heat and convey it outside said body. The presence of this element entails increases in size (due to the installation spaces but also to the provision of the air circuit), from the point of view of energy consumption (caused by the electric power consumption of the motor that drives the fan), in weight (due to the insertion of all the components of the cooling circuit) and most of all noise.  
      The heat emitted in the direction of the patient, in addition to being unpleasant for the patient (who is, however at a distance by virtue of which he/she is affected only by a limited fraction of the amount of heat released), is negative for the surgeon, who by having the lamp at a short distance from the back of his head is subjected to the maximum intensity of emitted heat.  
      Moreover, the light emitted by halogen lamps also comprises various components that belong to the ultraviolet frequency: the materials currently used (for example in fillings) are polymeric materials that cure easily if they are subjected to light radiation of a certain frequency, particularly the ultraviolet.  
      Therefore, when the surgeon operates by using these materials, he cannot use the orientable lamp with complete ease, since said lamp reduces considerably the curing times of said materials.  
      The average life of halogen lamps is rather short, and accordingly said lamps must be replaced frequently; further, in the final step of their life their light flux degrades considerably and sometimes does not fall within the parameters set by the standards.  
     SUMMARY OF THE INVENTION  
      The aim of the present invention is to obviate the cited drawbacks and meet the mentioned requirements, by providing a dental lamp particularly for medical and dental surgeries that complies with currently applicable statutory provisions and has a low heat emission.  
      Advantageously, an object of the present invention is to have an emitted light of constant intensity during operating hours and during the life of the lamp.  
      Another object of the present invention is to have an emitted light beam of adjustable intensity.  
      Another object of the present invention is to have an emitted light beam that is substantially free from infrared components and optionally has a reduced ultraviolet component, in order to avoid the curing of photopolymerizing materials.  
      Another object of the present invention is to reduce considerably the weights with respect to a conventional lamp by not requiring the presence of parabolic reflectors.  
      Within this aim and these objects, another object of the present invention is to provide a dental lamp that is simple, relatively easy to provide in practice, safe in use, effective in operation, and has a relatively low cost.  
      This aim and these and other objects that will become better apparent hereinafter are achieved by the present dental lamp particularly for medical and dental surgeries, of the type that comprises an orientable arm that is rigidly coupled at one of its ends to a fixed structure and has the opposite end rotatably associated with a box-like body provided with a screen and a light source, characterized in that said light source comprises a plurality of luminescent diodes, known as LEDs, which are aligned with respective guides for the emitted light beam, the beam emission directions of all the diodes being substantially convergent. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Further characteristics and advantages of the invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment of a dental lamp particularly for medical and dental surgeries, illustrated by way of non-limiting example in the accompanying drawings, wherein:  
       FIG. 1  is a schematic perspective view of an apparatus for dental examinations, on which a lamp according to the invention is mounted;  
       FIG. 2  is a plan view of a lamp according to the invention;  
       FIG. 3  is a sectional view, taken along the line III-III of  FIG. 2 , of a lamp according to the invention;  
       FIG. 4  is a sectional view, taken along the line IV-IV of  FIG. 2 , of a lamp according to the invention;  
       FIG. 5  is an enlarged-scale view of the detail V of  FIG. 3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      With reference to the figures, the reference numeral  1  generally designates a dental lamp particularly for medical and dental surgeries.  
      The dental lamp  1  is suitable for installation on apparatuses of dental studies that are constituted by a footing  2 , which rests on the ground and through which they are connected to the electrical, hydraulic and compressed air supplies, by a chair  3  (mounted on the footing  2 ), and by a plurality of auxiliary elements for the surgeon.  
      The footing  2  is generally suitable to move vertically the components that are associated with it by way of the presence of traction elements (not shown in the figure), which are generally constituted by an electric motor and corresponding gears or by a hydraulic piston.  
      The chair  3  on which the patient lies comprises a seat  4 , a back  5  and a headrest  6 , all of which can move with respect to each other in order to meet the requirements of the patients and of the surgeon.  
      Laterally to the chair  3  and rigidly with respect to the footing  2  there is a column  7 , in which there is a management and control unit, which is not shown in the figure.  
      At the top of the column  7  there is usually a basin  8 ; respective supporting arms  9  and  10  extend from the lateral surfaces thereof, and the first arm  9  is associated with an instrument supporting assembly  11  and the second arm  10  is associated with an aspirator assembly  12 .  
      At the top of the column  7 , proximate to the basin  8 , an arm  13  is rotatably coupled, is provided with articulations  14  in order to facilitate its movement, and rotatably supports the lamp  1  at its free end.  
      The dental lamp  1  is comprised within a box-like body  15 , which is provided with a screen  16 ; the box-like body  15  internally accommodates a light source comprising a plurality of luminescent diodes  17 , known as LEDs, in which the respective beam emission directions substantially converge.  
      The screen  16  is designed to protect all the components installed inside the box-like body  15  against any unwanted impacts or contacts: in the described embodiment, said screen has an elliptical base and is made of a material such as plastics with a thickness comprised between 2 and 5 mm. The screen  16  is fixed on the box-like body  15  by means of removable retention elements, which are not shown in the figure.  
      The diodes  17  of the type used emit a white light beam with a color temperature of approximately 5500 K, are voltage- and current-adjustable, and have an average life on the order of 50,000 hours.  
      In the embodiment described in  FIG. 2 , there are eight diodes  17 , arranged substantially along the perimeter of an ellipse. Optionally, other diodes  17  might be added to the configuration shown in  FIG. 2 . Each one of the light-emitting diodes  17  used for the embodiment described has a power of three watts: the choice of this power is due to a compromise between good intensity of the emitted light beam and low heating of said diodes during operation.  
      As already mentioned, the light-emitting diodes  17  emit a beam of light with a color temperature of substantially 5500 K, a value which is within the range prescribed by the standards; this color temperature ensures that the emitted light is almost perfectly white, ensuring that the operator has optimum conditions for distinguishing colors.  
      This color temperature ensures that the light-emitting diodes  17  emit a light beam with a frequency that is substantially lower than the ultraviolet and substantially higher than the infrared: this reduces the risk of facilitating the curing of the photopolymerizing polymers (which are sensitive to the ultraviolet) used for certain dental treatments and also avoids biasing the perception of colors and reduces the heating of the face of the patient due to radiation.  
      The diodes  17  are mounted on a common base  18 , in which the light-emitting end is arranged within a light guide such as a light guiding cone  19 , and are aligned with respective lenses  20 , which are fixed frontally to the screen  16  in the box-like body  15 . The base  18  is a common board for wiring electronic circuits, and on said board it is convenient in certain cases to arrange finned surfaces in order to dissipate the heat generated by the power supply components. The power supply values (voltage and current) must allow control and modulation in order to allow to vary the intensity of the light beam (by varying the intensity of the current), and the components for conditioning the power supply are fundamental, since the diodes  17  require stabilized input values.  
      The light-emitting diodes  17  are connected electrically in series, and a Zener diode is connected in parallel on each one and is intended to allow electric current to flow if the light emitting diode fails: it is thus possible to ensure the operation of the lamp, albeit in a reduced mode, if some light-emitting diodes  17  are not working.  
      The lenses  20  are fixed to the light guiding cone  19  and are optionally inclined with respect to it, and therefore are offset axially with respect to the corresponding diodes  17 .  
      The light guiding cones  19  may be provided as a single ring (which comprises them all), generally made of a material such as plastics, with a substantially elliptical base; the exemplifying thickness of said ring is lower than 25 mm and the lower face is arranged above the base  18 , with the holes at the diodes  17  (holes provided with a diameter that approximates the diameter of the diodes  17 ) mounted on the base  18 . The upper face of the ring has holes that are suitable to accommodate the lenses  20 . The axis of each one of the elementary cones  19  is inclined with respect to the axis of the ring, and said inclination entails that the lenses  20  are axially offset with respect to the diodes  17  by a length comprised between 1 and 10 mm; further, the seats of the lenses  20  may accommodate the lenses  20  so that they are arranged at an angle comprised between 0° and 10°.  
      Once the lenses  20  have been arranged in the respective seats of the ring, said lenses must be locked by way of appropriate gaskets (or other equivalent fixing means); the lenses  20  of the type used in the particular embodiment described in the figure are biconvex and have a diameter comprised between 20 and 24 mm.  
      It may be convenient to insert a ventilation element inside the box-like body  15  in order to remove the maximum possible amount of heat, so as to make all the components work in optimum temperature conditions.  
      The operation of the invention is intuitive: by orienting the lamp  1  toward the patient, the light beam must strike the patient so as to illuminate with maximum intensity the mouth, while having a reduced emission intensity at the eyes of the patient (as required by the standards).  
      The arrangement of the diodes  17  ensures that the lighting of the mouth of the patient has an extremely uniform distribution, thus obtaining a lamp  1  whose characteristics exceed by far the requirements of the standards. Further, the lamp  1 , as a consequence of the minimal amount of heat emitted by the diodes  17 , might also be provided without electromechanical heat dissipation systems, thus reducing manufacturing costs and overall weight.  
      The screen  16 , by not having to provide a filtering action on the emitted light beam, can also be provided with a reduced thickness and with transparent materials having a low relative density, with the advantage of further reducing the weight of the lamp  1 .  
      It has thus been shown that the invention achieves the intended aim and objects.  
      The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.  
      For example, the number of diodes  17  used for each lamp  1  can also be lower than the described number (eight or more diodes  17 ).  
      By using diodes  17  that have a different (higher) power than the selected ones it is possible to achieve the same light beam intensity: the concentration of the beam in the area prescribed by the standards in this case is obtained by appropriately shaping the guiding cones  19  or by providing a common parabolic reflector that concentrates the light projection.  
      The lamp  1  can also be mounted on the wall, floor or ceiling (it is therefore not necessary to install it in dental surgery apparatuses such as the one shown in  FIG. 1 ).  
      All the details may further be replaced with other technically equivalent ones.  
      In the described embodiments, individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other embodiments.  
      Moreover, it is noted that anything found to be already known during the patenting process is understood not to be claimed and to be the subject of a disclaimer.  
      The embodiment of the present invention shall be carried out in the most scrupulous compliance with the statutory and regulatory provisions related to the products of the invention or correlated thereto and following any required authorization of the corresponding competent authorities, with particular reference to regulations related to safety, environmental pollution and health.  
      In practice, the materials used, as well as the shapes and the dimensions, maybe any according to requirements without thereby abandoning the scope of the protection of the appended claims.  
      The disclosures in Italian Patent Application No. B02004A000412 from which this application claims priority are incorporated herein by reference.