Patent Publication Number: US-6988891-B2

Title: Curing light

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This patent application is a continuation-in-part of Ser. Nos. 10/016,992; 10/017,272, now U.S. Pat. No. 6,783,362; Ser. No. 10/017,454; and Ser. No. 10/017,455; each of which was filed on Dec. 13, 2001, and each of which is a continuation-in-part of U.S. patent application Ser. No. 09/405,373 filed on Sep. 24,1999, now U.S. Pat. No. 6,331,111, and priority is claimed thereto. Priority is also claimed to U.S. Provisional Patent Application Ser. No. 60/304,324 filed on Jul. 10, 2001. 

   BACKGROUND OF THE INVENTION 
   The inventions relate to the field of curing lights that may be used to cure light activated composite materials. More particularly, the inventions relate to curing lights of various configurations that use semiconductor light sources to provide light of a wavelength and power level desired to effect curing. In many fields, composite materials, such as monomers and an initiator, are cured into durable polymers by use of a light source of appropriate wavelength to excite the initiator into initiating polymerization, and sufficient power to carry polymerization through to adequate completion. 
   In the prior art, various light sources have been used for the purpose of curing composite materials. Halogen bulbs, fluorescent bulbs, xenon bulbs, and plasma-arc lights have been used. More recently, there have been some efforts to produce an effective curing light using light emitting diodes (LED&#39;s), but those efforts have not met with widespread acceptance in the marketplace. 
   The prior art described above suffers from several disadvantages. First, many of those prior art lights generate a wide spectrum of light rather than light just of the desired wavelength for composite curing. Consequently, those prior art lights generate unnecessary heat. Second, many of those prior art lights require light transfer systems such as a light guide or fiber, which many embodiments of the present invention omit, providing a smaller and more efficient unit. Third, many of the prior art systems require an elaborate cooling system to handle heat, creating a large, heavy and expensive curing light. Many embodiments of the invention use a unique heat sink structure that avoids the need for complicated, noisy and expensive cooling systems. Many embodiments of the invention use a semiconductor light source and package which provides high power light for use in curing composite materials. Additional points of difference between the inventions and the prior art will become apparent upon reading the text below in conjunction with the appended drawings. 
   SUMMARY OF INVENTION 
   It is an object of some embodiments of the invention to provide a curing light system that uses a semiconductor light source to produce light capable of curing composite materials. Curing composite materials will involve polymerizing monomers into durable polymers. Various physical, electrical and semiconductor structures, materials and methods are provided to achieve this object. Additional objects, features and advantages of the invention will become apparent to those skilled in the art upon reading the specification and reviewing the appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  depicts a battery-powered Curing light that uses a single light emitting diode chip as a light source. 
       FIG. 2  depicts a cross-section of the light of  FIG. 1 . 
       FIG. 3  depicts an AC-powered Curing light that uses a single light emitting diode chip as a light source. 
       FIG. 4  depicts a cross section of the light of  FIG. 3 . 
       FIG. 5  depicts a battery-powered curing light that uses two light emitting diode chips as a light source. 
       FIG. 6  depicts a cross-section of the light of  FIG. 5 . 
       FIG. 7  depicts an AC-powered curing light that uses two light emitting diode chips as a light source. 
       FIG. 8  depicts a cross-section of the light of  FIG. 7 . 
       FIG. 9  depicts a battery-powered curing light that uses three light emitting diode chips as a light source. 
       FIG. 10  depicts a cross-section of the light of  FIG. 9 . 
       FIG. 11  depicts an AC-powered curing light that uses three light emitting diode chips as a light source. 
       FIG. 12  depicts a cross section of the light of  FIG. 11 . 
       FIG. 13  depicts a battery-powered curing light that uses three or more semiconductor chip modules mounted on a heat sink in a manner that the light they emit is collected by a reflector apparatus and focused by a lens means onto a light transport mechanism, such as a light guide, plastic stack or fiber. 
       FIG. 14  depicts a cross-section of the light of  FIG. 13 . 
       FIG. 15  depicts an alternative embodiment of the light of  FIG. 13 , in the light transport mechanism is replace by a distally-located mirror which reflects generally coherent light emitted from the light source in a desired direction for use. 
       FIG. 16   a  depicts a light which uses a plurality of light emitting semiconductor modules mounted on a heat sink as a light source, a focusing means to produce a generally coherent beam of light, and a light transport means such as optically conductive cable for transporting light to a location remote from the light source for use. 
       FIG. 16   b  depicts a cross section of the light of  FIG. 16   a.    
       FIG. 17   a  depicts a gross cross section of a light emitting diode chip that uses an insulative substrate. 
       FIG. 17   b  depicts a gross cross section of a light emitting diode chip that uses a conductive substrate. 
       FIG. 18   a  depicts epitaxial layers of a light emitting diode chip that uses an insulative substrate. 
       FIG. 18   b  depicts epitaxial layers of a light emitting diode chip that uses a conductive substrate. 
       FIG. 19   a  depicts a top view of a light emitting diode chip array (single chip) with an insulative substrate. 
       FIG. 19   b  depicts a top view of a top view of a light emitting diode chip array (single chip) with a conductive substrate. 
       FIG. 20   a  depicts a side view of a chip package for a light emitting chip that shows a light emitting diode chip with an insulative substrate mounted in a well of a heat sink, with electrical connections and light emission shown. 
       FIG. 20   b  depicts a perspective view of a chip package for a light emitting chip with an insulative substrate that shows a chip array mounted in a well of a heat sink. 
       FIG. 21   a  depicts a side view of a chip package for a light emitting chip that shows a light emitting diode chip with a conductive substrate mounted in a well of a heat sink, with electrical connections and light emission shown. 
       FIG. 21   b  depicts a perspective view of a chip package for a light emitting chip with a conductive substrate that shows a chip array mounted in a well of a heat sink. 
       FIG. 22   a  depicts a side view of a chip package for a light emitting chip mounted in a well of a heat sink according to the so-called ‘flip chip’ design, the chip having an insulative substrate. 
       FIG. 22   b  depicts a side view of a flip chip mounted on a flip chip pad. 
       FIG. 22   c  depicts a perspective view of a flip chip pad. 
       FIG. 22   d  depicts a perspective view of the chip package of  FIG. 22   a.    
       FIG. 23  depicts a side view of a flip chip package with a conductive susbtrate. 
       FIG. 24   a  depicts a side view of a light emitting diode chip package including the chip (insulative substrate) and heat sink surface mount arrangement with a protective dome, lens or cover. 
       FIG. 24   b  depicts a side view of a light emitting diode chip package including the chip (conductive substrate) and heat sink surface mount arrangement with a protective dome, lens or cover. 
       FIG. 25   a  depicts an array of light emitting chips with insulative substrates in surface mount arrangement in a single well of a heat sink. 
       FIG. 25   b  depicts a perspective view of the array of surface-mounted chips of  FIG. 25   a.    
       FIG. 26   a  depicts an array of light emitting chips with conductive substrates in surface mount arrangement in a single well of a heat sink. 
       FIG. 26   b  depicts a perspective view of the array of surface-mounted chips of  FIG. 26   a.    
       FIG. 27   a  depicts an array of light emitting chips with insulative substrates in surface mount arrangement in individual sub-wells of a well of a heat sink. 
       FIG. 27   b  depicts a perspective view of the array of surface-mounted chips of  FIG. 27   a.    
       FIG. 28   a  depicts an array of light emitting chips with conductive substrates in surface mount arrangement in individual sub-wells of a well of a heat sink. 
       FIG. 28   b  depicts a perspective view of the array of surface-mounted chips of  FIG. 28   a.    
       FIG. 29   a  depicts a light emitting surface mount chip package including array of chips, heat sink and protective dome, lens or cover according to the chip and surface mount configuration of  FIG. 25   a  above. 
       FIG. 29   b  depicts a light emitting surface mount chip package including array of chips, heat sink and protective dome, lens or cover according to the chip and surface mount configuration of  FIG. 26   a  above. 
       FIG. 30   a  depicts a light emitting surface mount chip package including array of chips in sub-wells, heat sink and protective dome, lens or cover according to the chip and surface mount configuration of  FIG. 27   a  above. 
       FIG. 30   b  depicts a light emitting surface mount chip package including array of chips in sub-wells, heat sink and protective dome, lens or cover according to the chip and surface mount configuration of  FIG. 28   a  above. 
       FIG. 31   a  depicts a side view of a single surface mount light emitting diode chip mounted to an elongate heat sink in a manner such that light from the chip is emitted at generally a 90 degree angle to the longitudinal axis of the elongate heat sink. 
       FIG. 31   b  depicts a bottom view of the device of  FIG. 31   a.    
       FIG. 32   a  depicts a cross-sectional side view of an elongate heat sink having two light emitting semiconductor chips in surface mount configuration in an angled orientation in order to present overlapping light beams for an enhanced density light footprint. 
       FIG. 32   b  depicts a bottom view of the device of  FIG. 32   a.    
       FIG. 33   a  depicts a cross-sectional side view of an elongate heat sink having three light emitting semiconductor chips mounted on it in an angled orientation in order to present overlapping light beams for an enhanced density light footprint. 
       FIG. 33   b  depicts a bottom view of the device of  FIG. 33   a.    
       FIG. 33   c  depicts a bottom view of the heat sink of  FIG. 33   a  and  33   b  to permit the reader to understand the angular orientation of the light emitting semiconductor chips. 
       FIG. 33   d  depicts a side view of the heat sink for 3 surface mounted LED&#39;s. 
       FIG. 34   a  depicts a light shield which may be used in conjunction with curing lights of the invention to shield human eyes from light emitting by the curing light. 
       FIG. 34   b  depicts a focus lens which may be used to focus light emitted by curing lights of the invention in order to present a denser light footprint. 
       FIG. 34   c  depicts a light module with reflective cone installed. 
       FIG. 34   d  depicts a reflective cone. 
       FIG. 35  depicts a block diagram of control circuitry that may be used with the embodiments of the inventions that utilize AC power. 
       FIG. 36  depicts by a block diagram of control circuitry that may be used with the embodiments of the inventions that utilize battery power. 
       FIG. 37  depicts a graph of electrical current input I to the light emitting semiconductor chip(s) of the curing light versus time in a pulsed power input scheme in order to enhance light power output from the chip(s) and in order to avoid light intensity dimunition due to the heat effect. 
       FIG. 38  depicts a graph of total light intensity output versus time in order to permit the reader to compare light intensity output when a current input pulsing scheme such as that of  FIG. 37  is used to a traditional continuous wave current input approach which generates a heat effect is used. 
   

   DETAILED DESCRIPTION 
   The inventions include various embodiments of curing light systems useful for curing light activated composite materials, principally by polymerizing monomers into durable polymers. The invented curing light systems have application in a variety of fields, including but not limited to medicine and dentistry where composite materials with a photoinitiator are used. The photoinitiator absorbs light of a particular wavelength and causes polymerization of the monomers into polymers. 
   Composite materials are applied to a surface and later cured by a variety of methods. One method includes use of a photoinitiator or multiple photoinitiators in the composite material. After the composite material has been placed in a desired location, light of a wavelength that activates the photoinitiator is applied to the composite. The light activates the photoinitiator and initiates curing of the composite material. In order to effect complete curing, the light must be of a wavelength to which the photoinitiator is sensitive, the light must be of a power level that will cause curing, and the light must be applied to the composite material for a sufficient duration of time. Although the light used to activate the photoinitiator must be of a wavelength to which a photoinitiator is sensitive, the light can come from a variety of sources, including gas lasers solid state lasers, laser diodes, light emitting diodes, plasma-arc lights, xenon-arc lights, and conventional lamps. In the present inventions, light is produced from a variety of different semiconductor chips arranged in numerous configurations. 
     FIG. 1  depicts a battery-powered curing light  100  that uses a single light emitting diode chip as a light source.  FIG. 2  depicts a cross-section of the light  100  of  FIG. 1 . The portable curing light system  100  includes a light source module  102  which generates light of a desired wavelength or multiple wavelengths for activating a photoinitiator or multiple photoinitiators and initiating curing of a light activated composite material. The light source module  102  has a light shield  103  for blocking light generated by the light emitting semiconductor chip(s)  150  from reaching human eyes and skin. The apparatus  103  could also be configured as a lens or focusing cone for modifying the footprint of light emitted by the curing light. The light emitting semiconductor chip(s)  150  are located at the distal end of the curing light, and at the distal end of the light source module  102 . The chip(s)  150  are oriented to emit light at generally a right angle with the longitudinal axis of the light source module or the longitudinal axis of the curing light handpiece, although chips could be mounted to emit light at from about a 45 degree angle to about a 135 degree angle with the longitudinal axis of the light source module, heat sink, or handpiece as desired. The curing light system  100  includes a housing  104  for containing and protecting electronic circuits and a DC battery pack. In some embodiments, the light emitting semiconductor chip(s) may be powered by from less than about 25 milliamps to more than about 2 amps. Many embodiments of the inventions will have chip(s) powered from about 350 milliamps to about 1.2 amps of current. Higher power embodiments of the inventions will often use more than about 100 milliamps of current. 
   A switch  105   a  is provided on the top of the housing  104  facing a direction opposite from the direction that light would be emitted from the light source module  103 . A second switch  105   b  is provided on the side of the housing. The switches  105   a  and  105   b  are devices such as a button or trigger for turning the light emission of the curing light on and off. A timer  106  is provided to control the duration of time that the curing light emits a beam of light. Control buttons to set and adjust the timer are depicted as  151   a  and  151   b.    
   An audible indicator or beeper may be provided in some embodiments of the invention to indicate when light emission from the curing light begins and ends. A first light emitting diode indicator lamp  107  is located on the housing in a visible location in order to indicate to the user low battery power. A second light emitting diode indicator lamp  108  is located on the housing in a visible location in order to indicate to the user that the battery is being charged. A main on/off switch to the curing light  160  is provided at the rear or proximal end of the housing. A wavelength selector may be provided in some embodiments of the invention so that the user may select the wavelength of light that he wishes to emit from the curing light, depending on the wavelength sensitivity of the photoinitiator in the composite material that he is using. The user may also select a combination of two or more wavelengths of light to be emitted together in some embodiments of the invention. 
   A separate battery charger module  109  is included in order to receive AC power from a traditional wall socket and provide DC power to the curing light system for both charging the batteries and powering the light source and control circuitry when the batteries if desired. The battery charger module  109  has a cable  109   a  and a plug  109   b  for plugging into a receptacle or connector  170  on the proximal end of the curing light housing  104 . The battery charger module  109  includes circuitry  109   c  for controlling battery charging of batteries  166 . 
   The light module  102  has a casing  161  that encases an elongate heat sink  162 . The casing  161  is separated from the heat sink  162  by a buffer layer  163  such as insulation tape and an air space may be provided therebetween for heat dissipation. Electrically conductive wires  164  to power the light-emitting semiconductor chip(s)  150 . Internally, we can see that the heat sink  162  is an elongate and curved structure which positions a semiconductor chip at its end in a convenient place for use without a light guide. At the distal end of the heat sink  162 , there may be a smaller primary heat sink or semiconductor chip module which includes a smaller primary heat sink. A semiconductor module may be covered by a protective cover or dome or a focus lens. The heat sink  162  may be an elongate structure or other shape as desired. Use of an elongate heat sink  162  rapidly transfer heat away from the chip(s)  150  for heat dissipation. If heat transfer and dissipation are not handled adequately, damage to the chip(s)  150  may result, or light output of the chip( 2 )  150  may be diminished. 
   The light source module  102  is removable from the housing  104  and interfaces therewith and mounts thereto by a connection plug  165 . One or more batteries  166  are provided to power the curing light during use. The curing light may have control circuitry  167  located in the housing  102 . Battery charger  109   c  is located in the power supply  109  for controlling battery recharging and direct powering of the curing light from wall outlet power when the batteries are low. The power supply  109  has an AC plug  109   d.    
   A unique advantage of the curing light system depicted in several embodiments of the invention is that all components, including the light source, batteries, control circuitry and user interface are conveniently located in or on a handpiece. This results in a very portable, yet compact and easy to use curing light system. Only when the batteries are being charged would the user need to have a cord attached to the curing light system or even be in the vicinity of AC power. However, the light system can be operated using power from a battery charger when the battery pack is being charged or when no batteries are being used. 
     FIG. 3  depicts an AC-powered curing light that uses a single light emitting diode chip as a light source.  FIG. 4  depicts a cross section of the light of  FIG. 3 . Referring to these figures, one embodiment of a curing light system  301  of the invention is depicted. The curing light system  301  includes a handpiece or wand  302 , cabling  303 , and a power supply  304  with an AC plug  304   a . Curing light control circuitry  304   b  may be located within the power supply  304  and is remote from the wand  302  in order to keep the wand compact and light weight. The handpiece or wand  302  has minimum size, weight and componentry for convenience of use. The handpiece  302  includes a housing  305 , an on/off switch or light output control  306 , an integral light source module  307 , and a device  309  which may be a light shield, light reflective cone or focus lens. The handpiece  302  receives electrical power from cabling  303 . A cable strain relief device  308  may be provided. A timer  310  may be provided with timer adjustment buttons  311  and  312  in order to control timed duration of light output from the curing light. All control circuitry  304   b  is located in a module remote from the handpiece  302 . 
   Referring to the cross section of  FIG. 4 , it can be seen that the heat sink  401  may be configured as an elongate device with a planar mounting platform on its distal end for mounting chips or chip modules thereto. The heat sink has a longitudinal axis, and the light emitting semiconductor chip(s) may be oriented at an angle with the longitudinal axis of the heat sink from about 45 to about 135 degrees. In some embodiments of the invention, the chips will be oriented to emit light at an angle with the heat sink longitudinal axis of 70 to 110 degrees, 80 to 100 degrees, or about 90 degrees. The heat sink distal end may be curved as desired to position a light emitting semiconductor device  401  thereon to be positioned in a location for convenient use. The semiconductor device  402  may be covered with a protective window, dome or focus lens  403 . The heat sink may occupy less than 50% of the length of the wand, more than 50% of the length of the wand, 60% of the length of the wand, 70% of the length of the wand, 80% of the length of the wand, 90% of the length of the wand, or up to 100% of the length of the wand. Electrical wire  404  provides power to the light emitting semiconductor device  402 . Insulation means  405  such as rubber insulators or insulation tape separate the heat sink  401  from the casing  305  and provide for airspace  406  therebetween for ventilation and heat dissipation. 
     FIG. 5  depicts a battery-powered curing light  501  that uses two light emitting diode chips as a light source.  FIG. 6  depicts a cross-section of the light  501  of  FIG. 5 . The curing light  501  includes a housing or casing  502  for containing and protecting the curing light components. A series of vents  503  are provided in the housing  502  to permit heat to escape therefrom and to permit air circulation therein. At the distal end of the housing  502 , a light module  504  is provided. The light module  504  may include an angled tip and may be removable and replaceable with other light modules of differing characteristics as desired. A light shield, light reflective cone or focus lens  505  is provided at the distal end of the light module  504 . At the proximal end of the curing light  501 , a handle  506  is provided for grasping the curing light. An on-off switch or trigger  507  is provided on the distal side of the curing light handle  506  for effecting light emission. On the proximal side of the curing light handle  506 , a main switch  507  for powering up the curing light  501  is located. A timer  509  with timer adjustment buttons  510  and  511  is provided to time the duration of light output. Indicator lights  512  and  513  are provided to indicate low battery and battery charging. A battery charger module  520  is provided with a power supply  521 , cable  522  and plug  523 . The plug fits into receptacle  601  for charging the battery  602  of the curing light  501 . 
   Referring to  FIG. 6 , Light module  504  includes a casing  603  that contains an elongate heat sink  604  that is separated from the casing  603  by insulators  605  to form a ventilating and heat-dissipating air space  606  therebetween. Heat sink  604  may include a thermoelectric cooler material  608  thereon for enhanced heat dissipation. Electrical wires  607  power a pair of light emitting semiconductor devices or modules  609   a  and  609   b . The semiconductor devices  609   a  and  609   b  are mounted on the heat sink  604  at a mounting receptacle  611  that has two adjacent angled planes oriented to cause the light output beams from the semiconductor devices  609   a  and  609   b  to overlap to provide an overlapped and enhanced intensity light footprint  610 . The mounting planes are oriented at an angle of from about 10 to about 180 degrees with respect to each other. The curing light  501  also includes a timer  509  with timer control buttons  621  and  622 , and electronic control circuitry  623 . A battery pack  602  is located inside casing  502  to provide operating power. The light module  504  is connected to housing  502  using an electrical plug  624 . The light module  504  can therefore be unplugged and replaced with another light module of different power characteristics or which emits a different wavelength of light for different usage applications. 
     FIG. 7  depicts an AC-powered curing light  701  that uses two light emitting diode chips as a light source.  FIG. 8  depicts a cross-section of the light  701  of  FIG. 7 . The curing light system  701  includes a handpiece or wand  702 , cabling  703 , and a power supply  704  with an AC plug  704   a . Control circuitry  704   b  is located within the power supply  704  and is remote from the wand  702  in order to keep the wand compact and light weight. The handpiece or wand  702  has minimum size, weight and componentry for convenience of use. The handpiece  702  includes a housing  705 , an on/off switch or light output control  706 , an integral light source module  707 , and a light shield  709 . The handpiece  702  receives electrical power from cabling  703 . A cable strain relief device  708  may be provided. A timer  710  may be provided with timer adjustment buttons  711  and  712  in order to control timed duration of light output from the curing light. All control circuitry  704   b  is located in a module remote from the handpiece  702 . Referring to the cross section of  FIG. 8 , it can be seen that the heat sink  801  may be configured as an elongate device with a longitudinal axis shared with the longitudinal axis of the wand. The light emitting semiconductor chip  802  and  803  are mounted to the heat sink  801  at an acute angle to each other in order to produce an overlapping and enhanced intensity light footprint. The heat sink distal end may be curved as desired to position the light emitting semiconductor devices thereon for convenient use. The semiconductor devices  803  and  803  may be covered by a protective window, dome or focus lens. The heat sink may occupy less than 50% of the length of the wand, more than 50% of the length of the wand, 60% of the length of the wand, 70% of the length of the wand, 80% of the length of the wand, 90% of the length of the wand, or up to 100% of the length of the wand. Electrical wire  804  provides power to the light emitting semiconductor devices  802  and  803 . Insulation means  805  such as rubber insulators or insulation tape separate the heat sink  801  from the casing  705  and provide for airspace  806  therebetween for ventilation and heat dissipation. A connection plug  810  is provided for connecting the power module to the curing light. Thermoelectric cooler material  820  is optionally provided on the heat sink for enhanced cooling. 
     FIG. 9  depicts a battery-powered curing light  901  that uses three light emitting diode chips or modules as a light source.  FIG. 10  depicts a cross-section of the light  901  of  FIG. 9 . The componentry of this curing light is as generally described previously except for its three light emitting diode light source structure. It uses three light emitting diode chips or chip modules  902   a ,  902   b  and  902   c  arranged in complementary angled configuration so that the light beams emitted by each overlap at a desired distance from the light source to form an overlapped and enhanced intensity light footprint  903 . The arrangement of 3 LED&#39;s is described elsewhere in this document. 
     FIG. 11  depicts an AC-powered curing light  1101  that uses three light emitting diode chips or modules as a light source.  FIG. 12  depicts a cross-section of the light  1101  of  FIG. 11 . The componentry of this curing light is as generally described previously except for its three light emitting diode light source structure. It uses three light emitting diode chips or chip modules  1102   a ,  1102   b  and  1102   c  arranged in complementary angled configuration so that the light beams emitted by each overlap at a desired distance from the light source to form an overlapped and enhanced intensity light footprint  1103 . 
     FIG. 13  depicts a battery-powered curing  1301  light that uses a plurality of semiconductor chip modules mounted on a heat sink in a manner that the light they emit is collected by a reflector apparatus and focused by a lens means onto a light transport mechanism, such as a light guide, plastic stack or fiber  1302 .  FIG. 14  depicts a cross-section of the light  1301  of  FIG. 13 . Many of the components of this light are as discussed previously for other curing light embodiments, and that discussion is not repeated here. However, the light source and light transport means are very different from embodiments discussed above. The curing light  1301  includes a housing  1303  which has a light transport means  1302  such as a light guide, plastic stack or fiber attached to it. The light transport means  1302  transports light from a light module to a remote location for use. The light transport means  1302  depicted has a curved distal portion  1304  to cause light  1305  to be emitted in a desired direction, such as at a right angle to the longitudinal axis of the curing light or the light transport means. The light transport means may be removable and replaceable with light guides of different lengths and configurations. A gross or secondary heat sink  1405  is provided for heat removal from the system. The secondary heat sink  1405  has a proximal side on which a thermoelectric material layer  1406  may be placed to enhance heat removal ability. Optionally, a fan  1407  may be provided to improve heat removal efficiency, and vents may be provided in the housing to encourage air circulation. The secondary heat sink  1405  may have mounted directly or indirectly to it a plurality of semiconductor light emitting chips or chip modules  1409 . Those chips  1409  may be mounted to a primary heat sink such as  1410 . Light emitted by the chips  1409  will be reflected by a reflector device  1411  such as a mirrored parabolic reflector to an optional lens or focusing device  1412  which focuses a generally coherent light beam onto the light transport means  1302 . The reflector may be of a desired shape for directing light, such as frusto-conical, parabolic or otherwise. If the light emitting devices are oriented so that the light which they emit is substantially directed toward the distal end of the curing light, the reflector may be omitted. A battery pack  1415  and control circuitry  1413  are provided. 
     FIG. 15  depicts an alternative embodiment of the light of  FIG. 13 . The curing light  1501  has no light transport mechanism and instead has a light exit tube  1502  that has a distal end with a mirror or reflector  1504  which can reflect a generally coherent light beam  1503  to a light exit  1505  in a desired direction for use, such as at a generally right angle to the longitudinal axis of the light module or the curing light. 
     FIG. 16   a  depicts a curing light curing light  1601  that has a light source and control module  1602  remotely located from a handpiece  1603  connected by a connection means  1604  that includes an optically conductive cable and electrical wires for electrical connection.  FIG. 16   b  depicts a cross section of the light of  FIG. 16   a . The light source and control module  1602  includes a housing  1610  with optional air vents thereon, electronic control circuitry  1611 , an electrical cord with power plug  1612 , a cooling fan  1613  for air circulation and heat dissipation, a heat sink  1615  which may be appropriately shaped to accept light emitting semiconductor devices on its distal side, such as having a concave hemispherical or parabolic portion, and having a thermoelectric cooler  1616  on its proximal side for enhanced heat dissipation. A plurality of light emitting semiconductor devices such as LED chip modules  1618  are mounted to the heat sink distal side so that they emit light into an optical system such as a focus lens  1619  which places a generally coherent light beam onto the optically conductive cable where it is transported to a distant handpiece  1603  that includes a housing  1651 , light exit  1650  for permitting light to be delivered to a composite material to be cured, and various controls such as light on/off control  1660 , timer display  1663 , and timer adjustment buttons  1661  and  1662 . The distal end of the handpiece housing  1670  may be angled from the longitudinal axis of the handpiece in for convenience of light application to a composite material. 
   As desired in various embodiments of the inventions, the light source may be a single LED chip, single LED chip array, an array of LED chips, a single diode laser chip, an array of diode laser chips, a VCSEL chip or array, or one or more LED or diode laser modules. The wavelength of light emitted from the semiconductor light source can be any desired wavelength or combination of different wavelength, depending on the sensitivity of the photoinitiator(s) in the composite material to be cured. Any of the semiconductor and heat sink arrangements described herein may be used to construct desired curing lights. 
   Referring to  FIG. 17   a , a light emitting diode (“LED”) chip  1701  is depicted in which the LED structure  1702  has been grown on top of or on one side of an insulative substrate  1703 . Electrodes  1704   a  and  1704   b  are provided to power the LED. In such a structure, all electrodes will be located on the top surface of the LED. Light is emitted from all sides of the LED as depicted. 
   A similar LED chip  1710  with a conductive substrate  1711  and accompanying LED structure  1712  and electrodes  1713  and  1714  is depicted in  FIG. 17   b.    
     FIG. 18   a  depicts an example of epitaxial layer configuration  1801  for an LED with an insulative substrate used in the invention. The LED includes an electrically insulative substrate such as sapphire  1802 . The substrate serves as a carrier, pad or platform on which to grow the chip&#39;s epitaxial layers. The first layer placed on the substrate  1802  is a buffer layer  1803 , in this case a GaN buffer layer. Use of a buffer layer reduces defects in the chip which would otherwise arise due to differences in material properties between the epitaxial layers and the substrate. Then a contact layer  1804 , such as n-GaN, is provided. A cladding layer  1805  such as n-AlGaN Sub is then provided. Then an active layer  1806  is provided, such as InGaN multiple quantum wells. The active layer is where electrons jump from a conduction band to valance and emit energy which converts to light. On the active layer  1806 , another cladding layer  1807 , such as p-AlGaN is provided that also serves to confine electrons. A contact layer  1808  such as p+ GaN is provided that is doped for Ohmic contact. The contact layer  1808  has a positive electrode  1809  mounted on it. The contact layer  1804  has a negative electrode  1810 . 
     FIG. 18   b  depicts epitaxial layer configuration  1850  for an LED with a conductive substrate. The LED includes an electrically conductive substrate such as SiC  1852  that has an electrode  1851  on it. The substrate serves as a carrier, pad or platform on which to grow the chip&#39;s epitaxial layers, and as a negative electrode in the chip. The first layer placed on the substrate  1852  is a buffer layer  1853 , such as n-GaN. A cladding layer  1854  such as n-AlGaN is provided followed by an active layer  1855  such as InGaN with multiple quantum wells. That is followed by a cladding layer  1856  such as p-AlGaN and finally a contact layer  1857  such as p+ GaN that has an electrode  1858  mounted on it. 
     FIG. 19   a  depicts a top view of an LED array on a single chip  1901  with a size a×b on an insulating substrate. The size of a and b are each greater than 300 micrometers. Semiconductor materials  1904  are located on an electrically insulative substrate (not shown). Positive and negative electrode pads are provided, each in electrical connection with its respective metal electrode strip  1902  and  1903  arranged in a row and column formation (8 columns shown) to create the array and power the chip. This structure enables the LED to emit light of greater power than that which is possible in a non-array traditional chip. 
     FIG. 19   b  depicts a top view of an LED array on a single chip  1950  with a size a×b on a conductive substrate. Each of sizes a and b is greater than 300 micrometers. Semiconductor materials  1952  are located on an electrically conductive substrate (not shown). Positive electrode pads are provided in electrical connection with a metal strip  1951  arranged in an array formation to power the chip. The substrate serves as the negative electrode in the embodiment depicted. 
   Referring to  FIG. 20   a , a side view of a surface mount LED chip package  2000  including the LED chip  2001  on a heat sink  2002  is provided. The LED chip depicted has an insulating substrate and is mounted in a well  2004  of the heat sink  2002  by the use of heat conductive and light reflective adhesive  2003 . Light is emitted by the chip in all directions, and light which is emitted toward the adhesive  2003  or the well walls is reflected outward in a useful direction  2020 . The chip is electrically connected via wires  2010   a ,  2010   b ,  2010   c  and  2010   d  using intermediary islands  2011  and  2012 . The LED chip is located in a circular well  2004  of the heat sink  2002 . The circular well is formed with sides or walls at about a 45 degree angle or other desired angle (such as from about 170 to about 10 degrees) so that light emitted from the side of the chip will be reflected from the walls of the well in a desired direction as indicated by arrows in the figure. This allows the highest possible light intensity to be obtained using a chip of given size. The well walls may have a light reflective coating to increase efficiency. 
   Referring to  FIG. 20   b , a perspective view of a LED chip array (single chip) chip package  2050  including the chip array  2051  on an insulative substrate in a well  2052  of a heat sink  2053  is depicted. 
   Referring to  FIG. 21   a , a side view of an LED chip module  2100  is provided. An LED chip  2101  with a conductive substrate is mounted in a circular well  2103  of a heat sink  2104  by use of heat conductive light reflective adhesive  2102 . A negative electrode  2110  is provided on the heat sink. Positive electrical connection is provided by wires  2105  and  2106 , and island  2107 . 
   Referring to  FIG. 21   b , a chip array package  2150  that includes an LED chip array  2151  with a conductive substrate mounted in a well  2152  of a heat sink  2153  with an electrode  2154  and wire connection  2155  is depicted. 
     FIG. 22   a  depicts a side view of a chip package  2200  for a light emitting diode chip array  2201  mounted in a well  2202  of a heat sink  2203  according to the so-called ‘flip chip’ design, the chip having an insulative substrate.  FIG. 22   b  depicts a side view of a flip chip  2201  mounted on a flip chip pad  2204 .  FIG. 22   c  depicts a perspective view of a flip chip pad  2204 .  FIG. 22   d  depicts a perspective view of the chip package  2200  of  FIG. 22   a . Intermediate islands or electrode pads  2201   a  and  2210   b  are provided on the flip chip pad to ease of electrical connection with the chip. Electrode bumps  2111   a  and  2111   b  are provided between the chip and the pad for electrical connection. The chip has an electrode  2201   b  on top and its epitaxial layers  2201   a  facing down toward the pad  2204  and the bottom of the well  2202 . The pad  2204  upper surface is light reflective so that light is reflected from the pad in a useful direction. The pad  2204  may be coated with a light reflective film, such as Au, Al or Ag. In such a package, all of the light emitted from the chip can be reflected back in the light exit direction for highest light output. 
     FIG. 23  depicts a flip chip package  2301  in which a chip  2302  with a conductive substrate is mounted upside down (electrode up) on a flip chip pad  2303  with light reflective and heat conductive adhesive  2304  in the well of a heat sink. Electrical connection takes advantage of the exposed electrode of the chip  2302 . 
   Referring to  FIG. 24   a , a high power LED package  2401  is depicted using a chip  2402  with an insulative substrate mounted in the well of a heat sink  2403  using heat conductive and light reflective adhesive  2404 . The heat sink is surrounded by a known insulating material  2405  that serves the purpose of protecting electrode and dome connections. The walls and bottom of the well may be polished to be light reflective, or may be covered, plated, painted or bonded with a light-reflective coating such as Al, Au, Ag, Zn, Cu, Pt, chrome, other metals, plating, plastic and others to reflect light and thereby improve light source efficiency. Electrodes and/or connection blocks are provided for electrical connection of the chip. An optical dome or cover  2410  may optionally be provided for the purpose of protecting the chip and its assemblies, and for the purpose of focusing light emitted by the chip. The dome may be made of any of the following materials: plastic, polycarbonate, epoxy, glass and other suitable materials. The configuration of the well and the dome provide for light emission along an arc of a circle defined by φ.  FIG. 24   b  depicts a similar arrangement for a chip package  2450  in which the chip  2454  has a conductive substrate and thus when mounted to the heat sink  2452  can use an electrode  2455  on the heat sink itself for electrical connection. Protective dome  2451  and insulating covering  2453  are provided. 
   Referring to  FIGS. 25   a  and  25   b , a chip package  2501  is provided with an array of light emitting semiconductor chips  2504   a ,  2504   b , etc. having electrically insulative substrates located in a single well  2502  of a heat sink  2503 . The chips are mounted by an electrically conductive and heat conductive adhesive  2605 . The chips are electrically connected to each other by wires  2505   a ,  2505   b , etc. 
   Referring to  FIGS. 26   a  and  26   b , a chip package  2601  is provided that has a heat sink  2602  with a single well  2603  and an array of LED chips  2604   a ,  2604   b , etc. in the well  2603 . The chips have electrically conductive substrates and an electrode  2606  is provided on the heat sink. 
   Referring to  FIG. 27   a , a chip package  2701  is depicted with an array of LED chips  2702   a ,  2702   b ,  2702   c , etc. is depicted, with each chip located in its own individual sub-well  2703   a ,  2703   b ,  2703   c  in a gross well  2704  of a heat sink  2705 . The chips have electrically insulative substrates. 
   Referring to  FIG. 27   b , a chip package  2750  is depicted that has an array of LED chips  2763   a ,  2763   b ,  2763   c  with electrically conductive substrates. Each LED chip is mounted in its own individual sub-well, all located within a gross well  2761  of a heat sink  2762 . 
     FIGS. 28   a  and  28   b  depict a chip package  2801  that has a heat sink  2802  with a gross well  2803  and a plurality of sub-wells  2804  therein, each sub-well having a light emitting chip  2805  with a conductive substrate within it. The heat sink  2803  has a negative electrode  2806  for electrical connection. 
   Referring to  FIG. 29   a , an LED chip module  2901  is depicted that has an array of LED chips  2902   a ,  2902   b , etc located in a well  2903  of a heat sink  2904 . Insulative covering  2910  as well as a cover or dome  2911  are provided respectively. The chips of  FIG. 29   a  have insulative substrates. 
   Referring to  FIG. 29   b , an LED chip module  2950  is depicted that has an array of LED chips  2951   a ,  2951   b , etc. located in a well  2955  of a heat sink  2954 . Insulative covering  2960  as well as a cover or dome  2961  are provided respectively. The chips of  FIG. 29   b  have conductive substrates and an electrode  2959  is provided on the heat sink. . 
   Referring to  FIG. 30   a , an LED chip module  3001  is depicted that has an array of LED chips  3002 , with each chip in a sub-well  3003  of a gross well  3006  of a heat sink  3005  and the entire module covered by a protective or focus dome  3012 . The chips have electrically insulative substrates. 
   Referring to  FIG. 30   b , an LED chip module  3050  is depicted that has an array of LED chips  3051 , with each chip in a sub-well  3052  of a gross well  3055  of a heat sink  3054  and the entire module covered by a protective or focus dome  3061 . The chips have electrically conductive substrates and there is an electrode  3056  on the heat sink. 
   Referring to  FIGS. 31   a  and  31   b , side and bottom views of a surface mount chip configuration are depicted for mounting a single LED  3100  or LED module (as described previously) to an elongate heat sink  3101 . Electrically conductive wires  3102   a  and  3102   b  and electrodes  3103   a  and  3103   b  are provided for powering the LED. The LED is mounted on a platform  3104  formed on the heat sink distal end. Mounting is achieved by use of light reflective and heat conductive adhesive  3105 . A cover or focus dome  3106  is provided over the LED. The heat sink has a longitudinal axis, and the LED is mounted so that the average beam of light that it emits is generally at a 45 to 135 degree angle with that axis, and in some instances at a right angle to it. 
     FIGS. 32   a  and  32   b  depict side and bottom views of an elongate heat sink  3201  having two light emitting semiconductor chips or modules  3202  and  3203  mounted on mounting platforms  3204   a  and  3204   b  using adhesive  3205   a  and  3505   b  (such as heat conductive or light reflective adhesive). The chips are mounted on the heat sink in an angled orientation with respect to each other in order to present overlapping light beams for an enhanced density light footprint  3204 . The angle of orientation of the chips is depicted as θ which can be from zero to 180 degrees, or from 30 to 150 degrees, or from 45 to 135 degrees, or from 70 to 110 degrees, or from 80 to 100 degrees or about 90 degrees, as desired. The chips are offset from each other by a desired distance ‘a’, which can range from zero to any desired distance. Wires and electrodes are provided to power the LED&#39;s. An optional thermoelectric cooler  3208  may be provided to enhance heat removal. 
     FIG. 33   a  depicts a cross-sectional side view of a light module that uses three light emitting chips or chip modules.  FIG. 33   b  depicts a bottom view of the same.  FIG. 33   c  depicts a bottom view of the heat sink and mounting platform arrangement.  FIG. 33   d  depicts a side view of the heat sink and mounting platform arrangement. An elongate heat sink  3301  is provided having three light emitting semiconductor chips or modules  3302 ,  3303 , and  3304  mounted on mounting platforms in an angled orientation with respect to each other in order to present overlapping light beams for an enhanced density light footprint  3306 . The mounting platforms depicted are generally planar and are arranged to present the densest useful light footprint. The modules may each include their own primary heat sink. The modules or chips may be mounted to the elongate heat sink using a heat conductive or light reflective adhesive as desired. Electrical wires and electrodes are used to power the chips or modules. An optional thermoelectric cooler  3308  may be provided. The mounting platforms  3305   a ,  3305   b  and  3305   c  can be seen more clearly in  FIGS. 33   c  and  33   d . The mounting platforms depicted are arranged in circular fashion at an angular offset θ with respect to each other, which in this case is 120 degrees. More mounting platforms could be used, and any desired arrangement of the mounting platforms could be accommodated. In  FIG. 33   d  it can be seen that the mounting platforms  3305   a ,  3305   b  and  3305   c  are arranged at an angle φ with the longitudinal axis of the heat sink  3301 . The angle φ can be from 0 to 90 degrees, from 10 to 80 degrees, from 20 to 70 degrees, from 30 to 60 degrees, from 40 to 50 degrees, or about 45 degrees as desired to generate the densest usable light footprint. 
     FIG. 34   a  depicts a light shield  3401  which may be used in conjunction with curing lights of the invention to shield human eyes from light emitting by the curing light. The light shield includes an orifice  3403  through which light from a curing light may pass, the receptacle  3403  being formed by the light shield body  3402 . A flare  3404  of the shield performs most of the protective function. 
     FIG. 34   b  depicts a focus lens  3402  which may be used to focus light emitted by curing lights of the invention in order to present a denser light footprint. The focus lens has an outer periphery  3405 , a light entrance side  3506  and a light exit  3507 . The focus lens may be designed according to known optical principles to focus light output from chips which may not be in an optimal pattern for use in curing. 
     FIG. 34   c  depicts a reflection cone  3408  in conjunction with LED module  3409 , which is mounted on a heat sink  3910  by using heat conductive adhesive  3411 . One or more connection wires  3412  may be provided to power the LED module  3409 . The purpose of the light reflective cone is to re-shape the light beam from the LED module to create a light footprint of desired size and density. The inner wall of the cone  3408  may be coated with a highly reflective material, such as the reflective materials mentioned elsewhere in this document. The light beam from the LED module will change its path and configuration due to being reflected by the cone  3408 . 
   A detailed depiction of the light reflective cone  3408  is provided in  FIG. 34   d,  which illustrates a cross-sectional view of the cone. An opening with an appropriate diameter “a” is provided at the proximal side of the cone for fitting to a light module of a curing light. The diameter “a” is chosen as an appropriate size for permitting light to enter therein. The cone has a total length “b”. Adjacent light entrance at “a”, a cylindrical portion of the cone is provided having a longitudinal length “c”. Following cylindrical portion “c”, there is a frusto-conical section of the cone interior having a length “b” minus “c”. A light exit is provided at the end of the cone opposite the light inlet. The light exit has a diameter “d”, where in many embodiments of the invention, “d” will be smaller than “a”. The exterior diameter of the cone at its point of attachment to a light module is “e”, where “e” is greater than “a”. As desired, the various dimensions of the cone as well as its basic geometry (such as conical, frusto-conical, cylindrical, parabolic, etc.) are selected to achieve a desired light footprint size and density. Preferably, at least some portion of the interior surfaces of the reflective cone will have the ability to reflect light to aid in increasing the density of a light footprint. Appropriate reflective surfaces are mentioned elsewhere herein. Example dimensions of the various portions of the reflective cone in one embodiment of the invention are as follow: a=from about 5 mm to about 8 mm; b=from about 5 mm to about 8 mm; c=from about 2 mm to about 3 mm; d=from about 4 mm to about 6 mm; e=from about 8 mm to about 10 mm. Actual structure and dimensions of a reflective cone or reflective attachment or light exit for a curing light may vary depending on product type and application and design choice. 
     FIG. 35  depicts a logic diagram  3501  of circuitry that may be used by AC-powered versions of the invented curing lights. AC power input  3502  is provided to a power switch source  3503  which outputs DC power to a main switch  3504 . Main switch  3504  powers the control circuit  3505  and the optional TE cooler  3506  if so equipped. Main switch  3504  also provides a constant current source  3507  for the timer  3508 , timer setup  3511 , timer activation switch  3572  and optional light output beeper  3513 . Constant current source  3507  also powers the light source  3509  to accomplish light output  3510 . 
   Referring to  FIG. 36 , a logic diagram  3601  of circuitry that may be used by battery-powered versions of the invented curing lights is depicted. AC power input  3602  is provided to a power switch source  3603  which outputs DC power to a battery charge unit  3604  that charges battery  3605 . The battery  3605  powers main switch  3507 . Main switch  3607  powers the control circuit  3608  that controls the optional TE cooler  3610  and the fan  3609 . Main switch  3607  also provides a constant current source  3611  for the timer  3613 , timer setup  3614 , timer activation switch  3615  and optional light output beeper  3616 . Constant current source  3611  also powers the light source  3612  to accomplish light output. An electrical voltage booster  3617  may be provided to increase the voltage from the battery to meet electrical requirements of the light source. 
   Referring to  FIG. 37 , a graph of electrical current input I to the light emitting semiconductor chip(s) of the curing light versus time in a pulsed power input scheme is depicted.  FIG. 38  depicts a graph of total light intensity output versus time in order to permit the reader to compare light intensity output when a current input pulsing scheme such as that of  FIG. 37  is used to a traditional continuous wave current input approach which generates a heat effect is used. A pulsed current input scheme is used in order to enhance light power output from the chip(s) and in order to avoid light intensity reduction due to the heat effect. It has been found that when operated in continuous wave mode, the heat effect or heat buildup in the light emitting semiconductor chips will cause a decrease in light output intensity over time, until a stabilized light output yield is reached  3802  at point in time  3803 . In contrast, when current input to the semiconductor light source is pulsed, a greater even level of light power output with greater intensity is achieved  3801 . Laboratory experiments have shown this increase d to be more than 20% in some embodiments, providing significantly increased light yield and stable light intensity output in exchange for a simple control modification. Each of the square waves in  FIG. 37  is a pulse of current input to the semiconductor light source, measured by “a=duration”, “b=rest period”, and “c=current input level (amps.)”. 
   Examples of some heat sink materials which may be used in the invention include copper, aluminum, silicon carbide, boron nitride natural diamond, monocrystalline diamond, polycrystalline diamond, polycrystalline diamond compacts, diamond deposited through chemical vapor deposition and diamond deposited through physical vapor deposition. Any materials with adequate heat conductance can be used. 
   Examples of heat conductive adhesives which may be used are silver based epoxy, other epoxies, and other adhesives with a heat conductive quality. In order to perform a heat conductive function, it is important that the adhesive possess the following characteristics: (i) strong bonding between the materials being bonded, (ii) adequate heat conductance, (iii) electrically insulative or electrically conductive as desired (or both), and (iv) light reflective as desired, or any combination of the above. Examples of light reflective adhesives which may be used include silver and aluminum based epoxy. 
   Examples of substrates on which the semiconductors used in the invention may be grown include Si, GaAs, GaN, InP, sapphire, SiC, GaSb, InAs and others. These may be used for both electrically insulative and electrically conductive substrates. 
   Materials which may be used to used as a thermoelectric cooler in the invention include known semiconductor junction devices. 
   The semiconductor light source of the invention should emit light of a wavelength suitable to activate photoinitiators in the composite material to be cured. 
   Heat sinks used in this invention can be of a variety of shapes and dimensions, such as those depicted in the drawings or any others which are useful for the structure of the particular light source being constructed. It should be noted that particular advantage has been found when attaching the semiconductor light source to a small primary heat sink, and then the small primary heat sink is attached to an elongate secondary heat sink to draw heat away from the semiconductor and away from the patient&#39;s mouth. 
   While the present invention has been described and illustrated in conjunction with a number of specific embodiments, those skilled in the art will appreciate that variations and modifications may be made without departing from the principles of the invention as herein illustrated, described, and claimed. 
   The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects as only illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.