MXPA00002974A - Optical irradiation device - Google Patents

Abstract

An optical irradiation device incorporating a cluster of LEDs (11, 43) arranged so that shaped facets of adjacent LEDs come together to increase the packing density of LEDs in the cluster. A light guide (41) collects light emitted by the LEDs. Two or more light guides (41) and LED clusters (43) may be arranged in series to produce a single light beam. A heat pipe (45) is provided to conduct heat away from the LEDs (43). The heat pipe (56) may be annular and contain an inner storage space for batteries (60) or the like.

Description

OPTICAL IRRADIATION DEVICE TECHNICAL FIELD This invention relates to an optical irradiation device, especially a compact portable irradiation device for use as a source of light polymerization. It had already been proposed to use light-emitting diodes, DEL, in a handheld device to produce a focused beam of light to cure dental materials. Blue light at a peak wavelength of about 470 nm is used to harden dental polymers containing camphorquinone as the photoinitiator in a methacrylate polymerization process. However, there is a problem in producing a sufficient level of irradiation even with a pooled arrangement of DEL, to cure the known dental polymers at the recommended time. At the lower irradiation levels generally available below 300 mW / cm2, longer cure times should be allowed, which reduce the efficiency of the dental treatment delivered. DESCRIPTION OF THE INVENTION An object of the present invention is to provide an optical irradiation device that employs DEL and therefore has the benefits of compaction, portability, roughness and long life, but which also produces improved levels of irradiation in, and above of, 300 mW / cm2.

According to a first aspect of the invention, the LEDs are grouped in a radiation device formed facets configured in the adjacent LEDs that allow them to be joined more closely than they could in some way with conventional spherical external surfaces as currently manufactured.

According to a second aspect, the invention consists of a tapered light guide for an otic irradiation device, whose light guide tapers from its inlet end to its outlet end and has an intermediate region of minimum diameter in which a fold was formed. According to a third aspect, the invention consists of an optical irradiation device that uses LED and incorporates a heat pipe to cool the LED. According to a fourth aspect, the invention consists of a heat pipe comprising internal and external walls that extend longitudinally from one end of the heat pipe to the other and define an annular space therebetween containing a material that serves to absorb heat by a phase change, the annular space being divided by internal walls into a plurality of fluid flow channels extending longitudinally between the ends, some of said channels being adapted to conduct the liquid / vapor phase of the hot end material from the heat pipe to the cold end, and other channels being adapted to return said liquid phase from the cold end of the pipe to the hot end.

According to a fifth aspect, the invention consists of an irradiation device that uses LED and a tapered light guide to collect the radiation emitted by the LED and supply it to an output beam, where two or more tapered light guides they are arranged in series such that the successive guides receive radiation from the present guides and a group of DEL is provided at the entrance end of each guide, each successive guide being preferably provided with a ring of LED around the exit end of the guide. previous guide The first aspect of the invention means that LEDs occupy more space than is available and a fixed number produces a higher radiant intensity. Therefore, smaller DEL numbers can be used to produce a desired level of irradiation, which in turn reduces the power required to drive the device and the heat generated by it. In addition, the device can be made more compact. The packaging of LEDs in this way, may imply a slight reduction in the output of each LED, but the more effective packing density produces an overall increase in irradiation. Usually, a central LED may have a polygonal outer surface and a first LED ring could be arranged around it, each with a flat face to abut a corresponding face of the central LED and possibly each having a pair of side radiation faces which adjoin DEL in the first ring. In addition, a second or more LED rings could be arranged concentrically with the first ring, each with respective adjacent flat side faces abutting each other and possibly with inwardly deviated faces abutting the respective faces facing outwardly of the inner ring LEDs. . Alternatively, a single ring or two or more concentric rings of LEDs could be used without a central LED. DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic cross section through a first embodiment of the invention comprising a set of DEL in hexagonal section; Figure 2 is a schematic cross section through a second embodiment of the invention comprising a set of an internal group of LEDs and an outer ring of LEDs; Figure 3 is a schematic cross section through a third embodiment of the invention comprising a set of two rings of DEL; Figure 4 is a schematic side elevation of a fourth embodiment of the invention; Figure 5 is a schematic longitudinal section through a fifth embodiment of the invention; Figure 6 is a schematic longitudinal section through a sixth embodiment of the invention; Figure 7 is a schematic cross section through a beam of light guide fibers with modified sections; Figure 8 is a schematic side elevation of a light guide according to another embodiment of the invention; and Figure 9 is a schematic cross-section through a heat pipe according to the invention. MODE FOR CARRYING OUT THE INVENTION In a typical optical irradiation device, according to the invention, a plurality of LEDs are grouped so as to direct the radiation emitted in a single beam. A set of DEL 43 is shown in a side view in Figure 4 and in the plan view or cross section in Figures 1 to 3. Each DEL comprises a joint of Pn semiconductor light emitter (not shown) that is encapsulated in an external plastic cover, the profile of which is shown in the drawings. The sides of the roof of the LEDs are configured to allow the LEDs to be grouped more closely in their bases, thus increasing the ratio of occupied space to not occupied in the set of LEDs. The tips of the LEDs are substantially spherical and transmit the radiation to form the beam. In the embodiment of the invention illustrated in Figure 1, the outer cover of the LEDs is hexagonal in cross section and the LEDs are grouped in the shape of a honeycomb as shown, with the adjacent facets abutting each other.

In the second embodiment of the invention illustrated in the Figure 2, a central 21 hexagonal cross section has facets abutting the adjacent facets of six DEL 22 in a first ring of DEL with radially extending side facets that allow adjacent LEDs in the ring to abut each other. A second ring of DEL 23 is disposed around the first ring of DEL and these DEL 23 have radially extending side facets which allow adjacent DELs in the ring to abut each other. In a third embodiment of the invention shown in Figure 3, an inner ring of nine DEL 31, in a first ring is contained within a second ring of DEL 432, and the radially extending side faces of the DELs in both rings allow adjacent DELs in each ring to abut each other. Both the second embodiment of Figure 2 and the third embodiment of Figure 3 can be modified by the addition of one or more concentric rings of DEL. Also, the circumferential facets of the LEDs of each ring can be configured to adjoin the similarly configured circumferential facets of the adjacent ring of the LEDs. In yet another embodiment, the central group of LEDs 21, 22, of Figure 2, can be replaced by the same number of LEDs in a honeycomb assembly. Still another embodiment may consist of the single ring of DEL 31 shown in Figure 3. It will be appreciated in the three embodiments illustrated, that the LEDs are mounted in a substantially uniform plane. To modify the conventional optical sphere shape of the external plastic cover of a LED, care must be taken to preserve as much as possible the focusing effect of the cover to maximize the total irradiation. However, because the cover of the existing LEDs has a tapered shape to assist in removal from the mold during manufacture, for example, using stencils, or the invention may employ LEDs that have been specially manufactured with the cover configuration required to better accommodate joint training. The configured facets of LEDs can be polished to improve reflection and help reduce and lose optical power. Additionally, a reflective metallic film can be applied to the facets configured to further enhance reflection. LEDs can also incorporate a microlens or microlens array to aid beam alignment. The electrical connections of the DEL, known as conductive frames 44, are connected to the respective positive and negative power terminals or busbars 42. Preferably, these terminals are adapted to have a dual function of heat vessels to help remove the heat generated by the DEL 43. Therefore, the terminals are formed of a good thermal conductor such as copper and are located at the optimum location in relation to the LEDs and the external surfaces of the device. In a particular embodiment, most adapted to the LED arrangement of Figure 3, the terminals 42 take the form of two concentric rings, each being adjacent to the bases of a ring of the LEDs 31 or 32. Preferably, the negative terminal is the external one since the conductive negative frames of the LEDs are generally heated more than the positive conductor frames 44. The normal optical irradiation device according to the invention also preferably incorporates a tapered light guide, shown as guide 41 in Figure 4, to collect light emitted by the LEDs and supply it as an output beam. It is known to use light guides with adiabatic optical tapers in optical irradiation devices so that there is a total internal reflection of the light since it is conducted from the light source to the output. However, an advantage of the invention is that the more compact cross-section of the DEL assembly means that the diameter at the entrance end of the light guide can be smaller and therefore a smaller angle of adiabatic taper (is to say, the ratio of the diameter of the input end to the output end of the light guide) can be provided in the light guide with the consequent more efficient transmission of radiant energy and increased illumination. This improvement compares more markedly with a conventional approach to simply increase the numbers of the LEDs in a set to ever increasing diameters by decreasing the beneficial effect in lighting and increasing the detrimental effect in compaction, heat generation and cost. In another embodiment of the invention, illustrated in Figure 6, two or more adiabatic tapered light guides 41 are arranged in series, each with a corresponding set of DEL 43, but with successive sets forming a ring around the end of a Light guide as you connect to the next. Alternatively, each successive ring of DEL 43 may be replaced by only one or a smaller number of DEL. This arrangement allows the overall diameter of the device to be kept relatively small since the sets of DEL 43 are arranged in groups along the length of the device.

In the preferred embodiment of Figure 4, a single guide 41 of tapered light is provided. If required, the light guide can be curved along its length, as shown in Figure 5, to direct the output beam in order to adapt a particular application, this being a known practice with light guides existing The light guide can be cast and bent acrylic plastic, or it can be made of glass and other optically transparent materials. An alternative light guide is illustrated in Figure 8 in which the flexure in the light guide 41 is provided in a warped section 46 in its length which reduces to a minimum diameter before widening again to a larger diameter towards its exit end. By forming the bending at the minimum diameter, the transmission of light reduces the loss of the light guide caused by bending, but the effective cross-sectional area of the output beam is maintained at the required level. Light guides of fused fiber bundles have the advantage that the individual fibers have a relatively small diameter so that they can be bent over a narrower radius without the larger losses associated with the larger diameter fibers when they are bent over the fiber. same radio. However, conventional fused fiber bundles have the disadvantage of a packing fraction loss, i.e., the external fiber bundle uses a significant proportion of the cross section of the light guide in which the fiber arrangement is directed. semiconductor, thus reducing the amount of transmitted radiation available from the semiconductor source. Preferably, therefore, in one embodiment of the invention, illustrated in Figure 7, the guide comprises a few shaped fibers 61 placed adjacent to each other and fused together. A guide to this design is manufactured by MicroQuartz Sciences Inc. of Phoenix, Arizona, USA. In this way, the diameter of each fiber is smaller than a single homogeneous guide rod so as to allow greater light transmission when bending around the same bending radius, but also the packing fraction is greatly reduced also on conventional fiber guides, resulting in a central availability greater than 90% at the entrance end of the guide.

In another embodiment of the invention, a graduated index optical light guide is used. A graduated index light guide has no hasty interface between the cluster and the center. Instead, the refractive index varies either radially or axially. In one embodiment, the gradient of the refractive index of the light guide varies both radially and axially so that the light energy is manipulated favorably. A guide that uses a step index could also be used with the same axial and radial variation in refractive index. In this way, the numerical aperture can vary at either end of the guide to achieve the desired transmission. In other embodiments of the invention, instead of providing a single tapered light guide, each LED or LED groups could be provided with their own light guide fiber incorporating an adiabatic optical taper and the output ends of these fibers could be collected together to form a single output beam. The input end of the fiber could be optically molded to the adjacent LED or group of LEDs for efficient transmission of radiation. In this way, the diodes can be separated more widely to dissipate unwanted heat. In yet another embodiment of the invention, each LED could be adjusted so that its outer cover extends into a fiber light guide which incorporates an adiabatic optical taper. In yet another embodiment, the section of the fibers can be modified so that the configured faces of the fibers are adapted together to reduce the interstitial space. One embodiment of this design could be shown in Figure 7. The light guide or light guides used according to the invention, can be formed with an external metallic coating to improve its performance. It will be appreciated that the irradiation of the device according to the invention can vary by changing the input power, the number of LEDs or by varying the adiabatic taper of the light guide. The cooling of the LED assembly can be aided in accordance with another aspect of the invention by providing that the electrical connections of each LED usually include a heat vessel to conduct it away from the heat of the LED microcircuits. Heat vessels are generally slow and inefficient to conduct heat away from a heat source compared to heat pipes. Heat pipes conduct heat away, quickly using the latent heat of a substance, such as water, which is evaporated by the heat of the source. The steam moves at high speed towards the end of the heat pipe cooler and condenses. The heat pipes are unique in their ability to conduct heat rapidly in this way. Figure 5 shows a device according to the invention incorporating a heat pipe 45 as a single lumen in the main body 46 of the device. The hottest part of the LED conductors is preferably placed closer to the heat pipe 45 or outer box 47 of the LED assembly so that the heat path of the hotter conductor is shorter. A thermal connector 48 may be provided between the DEL 43 and the end of the heat pipe 45. If required, additional forced cooling means may be used, for example, a fan 49 or Peltier device 50 in juxtaposition with the pipe. In addition, a heat container 51 can be provided. Due to the greater cooling capacity of the heat pipes, they allow the IEDs to be driven in such a way that they produce more radiation and therefore allow the manufacture of a more powerful device. For portable use, the LEDs are operated from the batteries 52, which are located in a handle 53 connected to the body 46, in Figure 5. However, the design of the heat pipe can be modified as shown in Figure 9 for accommodate the batteries. The heat pipe consists of two concentric heat conducting tubes 55, 56, with a bent interstitial heat conducting element 57 between these tubes similar in appearance to a length of the corrugated sheet wound in a tube. It lies inside the concentric tubes. The wicks 58 of the heat pipe can then be placed in alternative grooves in the corrugated sheet, while the empty grooves 59 allow the rapid movement of the steam formed at the hottest end of the heat pipe.

By designing the heat pipe in this manner, the batteries, capacitors, supercapacitors or other energy source 60 can be located within the inner wall 55 of the heat pipe. In some embodiments, for example, where there is a large number of LEDs, a heat container 51 may be necessary in addition to the heat pipe 45. Intermittent use of a LED irradiation device for dental curing means that with the Careful design, a heat container can be omitted. If cooling below room temperature is required, as may be the case in extreme environments, a Peltier 50 device can be added to the heat pipe, although a Peltier device will result in higher power consumption and a requirement for greater heat dissipation. The wavelengths of the LEDs used will depend on the applications of the device. A LED that emits blue light with a peak wavelength of about 470 mm is used to harden the dental polymers, but a LED that emits red light may be useful for photodynamic therapy, for example, cancer therapy. The wavelength of the light emitted by the LED can be modified in a light guide by combining the material of which it is composed of fluorescent material. This can serve to extend the wavelength of the emitted light so that it adapts to the particular application.

The choice of LED is also important in terms of its construction, diameter, irradiation and angular diffusion pattern of light. From a known scale of DEL, the best available choice has been determined as one with a diameter of 3mm instead of a diameter of 5mm and an angular diffusion of 30 degrees instead of 15 or 45 degrees. Nichia is the manufacturer of these DEL. It will be appreciated that the term "light emitting diode LED", as used herein, also includes laser diodes. The LEDs in the devices according to the invention can be operated in a pulse mode or modulated mode to vary the output radiation intensity in order to adapt the application and multiple LED groups, such as in the embodiment of the Figure 6, each can be generated in a different way. The power supply for the LEDs of the device according to this invention could be network power, battery power, capacitor, supercapacitor, solar power, pre-selection generator or generator driven by the mechanical effort of the operator or attendant. In one embodiment, a capacitor or supercapacitor could be used to activate the arrangement that has advantages over conventional rechargeable sources such as batteries. The capacitors can be instantly recharged virtually between one or more operation healing cycles when the unit is connected to a power source.

The power supply for the device can be rechargeable and can be designed to form an automatic electrical contact with the charging means of a base unit when coupled with the latter in the form of a cordless telephone set.

Claims (30)

1. CLAIMS 1. An optical irradiation device comprising an arrangement of light emitting diodes (LEDs) grouped so that the radiation they emit is directed in a beam characterized in that each LED is formed with multiple facets so that the adjacent LED facets they are joined together in close proximity through their length.
2. 2. A device according to claim 1, wherein the adjacent facets of DEL extend substantially parallel to each other.
3. 3. A device according to claim 1 or 2, wherein the adjacent facets of DEL abut one another.
4. 4. A device according to any of the present claims in which the LEDs are arranged in a ring with the side facets of adjacent LEDs joining together.
5. A device according to claim 4, in which the LEDs are arranged in concentric rings with the side facets of dEI adjacent to each ring joining together.
6. 6. A device according to claim 5, wherein the adjacent ring LEDs have radially directed facets joining together.
7. 7. A device according to any of claims 4 to 6, wherein a single LED is located within the ring or in the inner concentric ring.
8. 8. A device according to claim 7, wherein the single DEL has radially directed facets that join the facets of the LEDs in the ring or in the inner concentric ring.
9. 9. A device according to any of the preceding claims in which the LEDs are regular polygons in cross section.
10. 10. A device according to claim 9, in which the LEDs are hexagonal in cross section.
11. 11. A device according to any of the preceding claims, wherein the facets of the LEDs are polished.
12. 12. A device according to any of the preceding claims, wherein the facets of the dEI are provided with a reflective coating.
13. 13. A diode adapted for use in an optical irradiation device according to any of claims 1 to 12.
14. 14. A device according to any of the preceding claims, including a light guide for collecting light from the set of emitting diodes. of light.
15. 15. A device according to any of claims 1 to 13, wherein a light guide is provided for each light-emitting diode in the assembly.
16. 16. A device according to any of the preceding claims including a light guide for collecting light from the LED assembly, the light guide having an index that varies from one part to another in a manner that manipulates the light.
17. 17. A device according to any of the preceding claims including a light guide consisting of a few fibers formed individually before joining together.
18. 18. A device according to any of the preceding claims, including a light guide consisting of configured fibers packed together in a manner that reduces the packing fraction.
19. 19. An irradiation device employing LED and a tapered light guide for collecting radiation emitted by the LEDs and supplying it to an output beam, characterized in that two or more tapered light guides are arranged in series such that the successive guides receive Radiation of the preceding guides and a DEL or group of LEDs is provided at the entrance end of each guide.
20. A device according to claim 20, wherein each successive guide is provided with a ring of LED about the exit end of the preceding guide.
21. 21. A device according to any of the preceding claims in which the heat is removed from the LEDs by a heat pipe.
22. 22. A device according to claim 21, wherein a plurality of heat pipes are used to transfer heat from the LED.
23. 23. A device according to claim 21 or 22, wherein an annular heat pipe is used so that it can contain energy storage means.
24. 24. A device according to any of the preceding claims, including a Peltier device for cooling the LEDs.
25. 25. A device according to any of the preceding claims having a gun handle for containing energy storage means.
26. 26. A device according to any of the preceding claims, including a capacitor or supercapacitor to activate the device.
27. 27. An optical irradiation device comprising a plurality of LEDs and a heat pipe to cool the LEDs.
28. 28. A manual device for curing dental materials including an optical irradiation device according to any of the preceding claims.
29. 29. A heat pipe comprising internal and external walls extending longitudinally from one end of the heat pipe to the other and defining an annular space therebetween containing a material that serves to absorb heat by a phase change, the annular space being divided by internal walls into a plurality of fluid flow channels extending longitudinally between the ends, some of the channels being adapted to conduct the liquid / vapor phase of the material from the hot end of the heat pipe to the cold end and other channels being adapted to return the liquid phase from the cold end of the pipe to the hot end.
30. 30. A tapered light guide for an optical irradiation device, whose light guide tapers from its inlet end to its outlet end and has an intermediate region of minimum diameter at which a fold is formed.