LED-based dental exam lamp

Abstract

Disclosed herein is an improved dental operatory lamp having an LED light source that directs light to a reflector that in turn reflects the light to illuminate a treatment area. In one embodiment, the lamp is adapted for efficient transfer of heat from the light source and into the environment. In another embodiment, the lamp is adapted to generate a predetermined pattern of light optimal for the treatment area. In other embodiments, the lamp includes structural features that enable the lamp to maintain optimum light intensity and/or temperature. Also, disclosed herein are unique reflector embodiments that intentionally provide a generally smooth surface, without facets, that reflect light at all visible and infrared wavelengths.

Claims

1. A dental operatory lamp used to illuminate an examination area comprising: a plurality of LEDs comprising at least first and second LEDs having different color characteristics; and at least first and second user-selectable light spectra comprising different ratios of intensity emanating from the first and second LEDs, the first spectrum comprising white light with color temperature in the range 4000 K-6000 K and the second spectrum comprising light having reduced output in the wavelength range 400-500 nm, wherein the second spectrum comprises light characteristics adapted not to cure a dental adhesive.

2. The dental operatory lamp of claim 1, wherein the plurality of LEDs further comprises a third LED, the first LED adapted to produce red light, the second LED adapted to produce blue light, and the third LED adapted to produce green light.

3. The dental operatory lamp of claim 1, wherein the first LED is adapted to produce white light and the second LED is adapted to produce amber light.

4. The dental operatory lamp of claim 1, wherein said plurality of color LEDs comprises LEDs configured to emit at least three different colors.

5. The dental operatory lamp of claim 4, wherein said at least three different colors comprises at least three of blue, green, amber, and red.

6. The dental operatory lamp of claim 5, wherein said at least three colors comprises blue, green, amber, and red.

7. A dental operatory lamp configured to illuminate an examination area, comprising: a plurality of light emitting diodes (LEDs), wherein said lamp has first and second operating modes, the second operating mode having light characteristics adapted not to cure a dental adhesive; wherein the light characteristics adapted not to cure a dental adhesive comprises one or more light types selected from the group consisting of green, red, and amber.

8. The dental operatory lamp of claim 7, wherein said first operating mode comprises a cool white mode or a warm white mode.

9. The dental operatory lamp of claim 8, wherein said cool white mode is configured to produce light having a color temperature in the range of 4000-6000 degrees K.

10. The dental operatory lamp of claim 8, wherein said warm white mode is configured to produce light having a color temperature below 5000 degrees K.

11. The dental operatory lamp of claim 7, wherein said second operating mode comprises light having reduced intensity below 500 nm.

12. The dental operatory lamp of claim 7, wherein said first and second operating modes comprise at least first and second user selectable light spectra, the first spectrum providing white light with color temperature in the range 4000 K-6000 K, and the second spectrum having reduced output in the wavelength range 400-500 nm.

13. A dental examination lamp for illuminating an examination area comprising: a plurality of LEDs; and at least first and second user-selectable light spectra, the first spectrum comprising white light with color temperature in the range 4000 K-6000 K and the second spectrum comprising light having reduced output in the wavelength range 400-500 nm, wherein the second spectrum comprises light characteristics adapted not to cure a dental adhesive; wherein the light characteristics adapted not to cure a dental adhesive comprises one or more light types selected from the group consisting of green, red, and amber.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present invention, this invention can be more readily understood and appreciated by one of ordinary skill in the art from the following description of the invention when read in conjunction with the accompanying drawings in which:

(2) FIG. 1 is a perspective view of a dental operatory lamp according to a particular embodiment of the invention.

(3) FIG. 2 shows a side perspective view of a close up of the dental operatory lamp shown in FIG. 1 with a breakaway to reveal an LED light source.

(4) FIG. 3 illustrates a component arrangement and a representative LED light output in a dental operatory lamp.

(5) FIG. 4 illustrates an embodiment of an optical waveguide in a dental operatory lamp of the invention.

(6) FIG. 5 illustrates a representative illumination pattern for the dental operatory lamp according to one embodiment of the invention.

(7) FIG. 6 is a cross-section of a light module having a reflective interior reflective surface according to a particular embodiment of the invention.

(8) FIG. 7 is a perspective view of a dental operatory lamp according to a particular embodiment of the invention.

(9) FIG. 8 illustrates an embodiment of an optical light guide having predetermined patterned apertures for use in a dental operatory lamp of the invention.

(10) FIG. 9 illustrates an embodiment of an optical light guide having an adjustable iris for use in a dental operatory lamp of the invention.

(11) FIG. 10 is a front view of a reflector embodiment for use in a dental operatory lamp.

(12) FIG. 11 is a cross-sectional view of a first embodiment of a reflector shown in FIG. 11 along axis 12-14.

(13) FIG. 12 is a cross sectional view of a second embodiment of a reflector shown in FIG. 10 along axis 12-14.

(14) FIG. 13 shows a rear perspective view of the reflector embodiment shown in FIG. 10.

(15) FIG. 14 is a front view of a dental operatory lamp embodiment that includes a front filter.

(16) FIG. 15 is a side view representation of a dental operatory lamp constructed according to principles of the invention;

(17) FIG. 16 illustrates a component arrangement and a corresponding light output for a module;

(18) FIG. 17 is a cross-section taken along an axis of a light module constructed according to principles of the invention;

(19) FIG. 18 is an end view of a first collimating lens used in certain embodiments of the invention;

(20) FIG. 19 is a cross-section taken through section 5-5 in FIG. 18 and looking in the direction of the arrows; and

(21) FIG. 20 is a cross-section, similar to FIG. 19, taken through a second, alternative, collimating lens.

DETAILED DESCRIPTION OF THE INVENTION

(22) Although the foregoing description contains many specifics, these should not be construed as limiting the scope of the present invention, but merely as providing illustrations of some representative embodiments. Similarly, other embodiments of the invention may be devised that do not depart from the spirit or scope of the present invention. Features from different embodiments may be employed in combination.

(23) FIG. 1 illustrates a perspective view of a current embodiment of the invention, generally indicated at 100, of a light source structure constructed according to principles of the invention. Light source structure 100 may generally be characterized as a lamp. Lamp 100 is powered by electricity, and functions to provide illumination to a work area disposed a distance from the lamp front, generally indicated at 102. Desirably, the work area illuminated by lamp 100 is shadow-free, and appears relatively uniform in illumination color and intensity. For most applications, the illuminated target work area is considered to have an approximately flat footprint and a depth normal to that footprint. That is, the illuminated region is generally structured to encompass a volume disposed proximate the footprint.

(24) Illustrated lamp 100 can include an attachment structure (not shown) operable to connect lamp 100 to suspension structure in the work area. Such an attachment structure is typically attached at a back 106 or sides 107 of lamp 100, although any convenient arrangement is operable. Typical suspension structure in a dental operatory permits a user to orient the lamp in space operably to aim the light output of lamp 100 at the desired target area. Certain embodiments of the invention provide a lamp having reduced weight and/or intrusive volume compared to commercially available lamps. Such reduced weight lamps permit a corresponding reduction in mass of the lamp suspension arrangement, thereby increasing ease of manipulation of the lamp to orient its output toward a target.

(25) In use in an environment such as a dental operatory, a front shield (not shown) can be provided as a protective cover to block migration of dust and contaminated aerosols into the lamp interior. A front surface of such a shield may be structured to provide an easily cleanable surface, whereby to maintain sterility of the operatory area. In certain embodiments, the shield may incorporate one or more lenses to focus, or otherwise modify, the light output of lamp 100. Whether or not a focusing lens is provided, a shield made from Lexan, or other similar optically useful and formable material, can be provided to completely encase the front of a dental lamp to resist contamination of, and to facilitate cleaning of, the lamp. The shield may be injection molded and may include focusing lenses. Desirably, the shield, or a portion of lamp housing 114, can be hinged, or otherwise openable by a user, to provide access to the interior of lamp 100 for maintenance or replacement of a light generating element.

(26) With reference to FIG. 3, an LED 118 emits light indicated by a plurality of rays 120. An operable LED can include a 3 watt LED, such as that sold by Lumileds Lighting US, LLC under the Brand name Luxeon, part number LXHL-LW3C.

(27) Typically, a reflective element, generally indicated at 116, is provided to direct the LED's light output toward a target. In a particular embodiment, reflective element 116 can be a concave aspheric reflector which collects the light emanating from the mixing rod and focuses it onto the plane of the patient's face (image plane). The reflector surface contour can be a simple 2D ellipse section revolved around the central optical axis. A focusing lens 209 may be included in an arrangement effective to collimate rays 120 and further direct them to an illuminated area indicated at 126. In certain embodiments of the invention, area 126 corresponds to the target footprint of the lamp 100. In such case, it is desired that the illumination emitted from each module 118 is substantially uniform over area 126. Certain rays 128 may be emitted in a direction other than desired for impingement on area 126. Such rays 128 are characterized as stray light. As indicated by the illustrated collection of rays 120, area 126 sometimes has a higher intensity of illumination at its center, and may fade to a decreased intensity near its perimeter, as discussed with reference to FIG. 5. In a preferred embodiment, light is illuminated in a generally rectangular pattern having a perimeter that is starkly contrasted with respect to the non-illuminated region surrounding the rectangular pattern. In another embodiment, the LED light source 118, lens 209, and all associated optics are arranged in harmony to produce a substantially uniform intensity over its illuminated footprint at a selected focal distance. Furthermore a waveguide 136 may be positioned between the LED light source 118 and reflector 116.

(28) As best shown in FIG. 2, LED light source 118 is typically mounted onto a bracket 112 associated with lamp housing 114. Desirably, the bracket 112 assembly is structured to provide simple and rapid installation and removal of LED light source 118, and includes connection structure for the electricity supplied to the LED and may further include a metal core circuit board 130. It is further desirable for bracket 112 to be formed from a material capable of conducting heat or, alternatively, to be associated with heat conducting pipes 134. Advantageously, bracket 112 and/or heat pipe 134, together with housing 132 may be structured and arranged to dissipate any heat generated by LED light source 118 in a direction away from the front 102 of the lamp 100. In some embodiments, use of heat pipe 134 is particularly desirable since a large heat sink positioned directly behind the metal core board with the heat-generating LEDs may significantly obscure the light focusing onto the image plane. Through use of a heat pipe 134 or equivalent structure, the heat can be conducted away via heat pipes 134 to a heat sink housing positioned on the back of the reflector where it does not obscure the light.

(29) As shown in FIG. 1, an exemplary heat sink housing can include heat sink fins 142. The heat sink fins 142 can be integral with the outer housing 114 of the lamp 100 and constructed of any heat conducting or dissipating material, such as cast aluminum. To increase cooling, a fan can be used to draw air into a gap 144 (see FIG. 1) between the reflector 116 and the housing 114. To maximize surface area and thus cooling, the inside of the heat sink/housing includes fins or ribs 142 that form air channels therebetween.

(30) Those skilled in the art will appreciate in view of the teachings herein that the heat pipe 134 may be substituted by other heat transfer conduits such as a solid rod having a high coefficient of heat transfer. Alternatively the heat transfer conduit is a hollow tube for conducting a flow of cooling air past the LED light source 118 for absorbing heat generated at the LED light source 118 and directing heated air to the heat sink 142. FIG. 7 shows a hollow tube heat transfer conduit 225 that communicates with the heat sink having fins 142. The embodiment includes a fan 227 that is in fluid communication with the hollow tube 225 for moving air through the tube 225. The embodiment shown in FIG. 7 further comprises a thermoelectric cooling device 230 adjacent to the LED light source 118. The thermoelectric cooling device may be of a type known in the art including, but not limited to, a Peltier-type device. The lamp includes a separate power supply 231 to the thermoelectric cooling device 230 that is preferably on the housing but in thermal isolation to the thermoelectric cooling device 230. Alternatively, the thermoelectric cooling device 230 is powered by the lamp power supply provided to the printed circuit board 130 via circuitry 513. The thermoelectric cooling device 230 acts in conjunction with the hollow tube 225 for transferring heat from the LED light source 118. Alternatively, the lamp can be equipped with the thermoelectric cooling device 230 without a heat transfer conduit.

(31) In order to produce homogenous light when multiple LEDs of different colors (for example, red, greed, blue, and amber) are used, the light emitting from each individual LED should sufficiently overlap the light from all the other LEDs. In a particular embodiment, a clear rectangular rod made of acrylic serves this function and is referred to herein as an optical waveguide 136. It is understood that the waveguide 136 can be made out of any suitable material capable of acting as an optical light guide. The performance of the waveguide 136 can be significantly enhanced with the addition of periodic features or ripples 150 on the outside walls of the waveguide. As illustrated in FIG. 4, light from multiple LEDs of different colors 154 (e.g., red, green, blue, and/or amber) are introduced through one end of the waveguide rod 136 and emanate from another end of the waveguide rod 136 as a composite white light 158. One particular embodiment combines the light from four different colored LEDs (red, blue, green, and amber) to produce white light. By varying the ratios of the different colors, the character of the white light can be changed. Specifically, white light with coordinated color temperatures (CCTs) of 4200 K and 5000 K can be produced while maintaining a high color rendering index (CRI), typically in excess of 75. Blue light typically occurs in the peak wavelength range of 445 nm to 465 nm. Green light typically occurs in the dominant wavelength range of 520 nm to 550 nm, amber light in the range of 584 nm to 597 nm, and red light in the range of 613 nm to 645 nm. A rod support 138 can be used to secure waveguide 136 in place.

(32) The waveguide 136 also serves the function of shaping the light received to emit light according to a predetermined pattern. The waveguide 136 shown serves to promote light in a rectangular pattern. Thus, the light shaping function is achieved whether one white LED is used or multiple LEDs of different colors.

(33) Multiple LEDs of each color can be mounted using reflow surface mount techniques to achieve optimum optical density. In a particular embodiment, a conventional metal core board (MCB) 130 can be used. Alternatively, a conventional fiberglass laminate (FR4) printed circuit board (PCB) material can be used. LEDs, particularly red and amber LEDs, have the characteristic that their light output decreases significantly as their temperature raises. Heat management can be critical to maintaining optimum light output and therefore the proper ratios of light intensity to maintain the desired CCT and CRI.

(34) The lamp 100 of the present invention includes a number of different operating modes which provide different light characteristics, as described in Table 1.

(35) TABLE-US-00001 TABLE 1 Nominal Approximate relative CCT peak intensity Mode ( K) CRI Blue Green Amber Red Comments Cool 5,000 70+ 0.72 0.70 0.75 1.00 Meets European white user preference for cooler white light. Warm 4,200 70+ 1.00 0.80 0.75 1.00 Meets US user white preference for warmer white light. No- N/A N/A ~0 0.30 0.60 1.00 Greatly reduced cure flux below 500 nm will not cure dental adhesives.
In this design, the ratios of the four colors are controlled with a variation of pulsed width modulation of the current. During the assembly and test of the lamp 100, each color is independently characterized for peak wavelength, spectral spread (full width half max), and illuminance (lux) at the image plane at a predetermined maximum current. Using test software based on both theoretical and empirical predictions, these values are used to generate a table of duty cycles for each wavelength at each of the three operating conditions: 4200K, 5000K, and No Cure modes at start up (board temperature equal to ambient temperature). These tables then can be stored on an electronic memory device (chip) that matches the serial number of the lamp. The PWM controller then looks up the duty cycle table on the memory chip and sets the duty cycles accordingly when the lamp is first started. At this time, the test software algorithm can also produce and store duty cycle tables for the full range of operating board temperatures, as discussed in more detail below.

(36) In a particular embodiment of the invention, temperature compensation or measurement may be included. Since each color LED has a different sensitivity to heat, a compensation algorithm can be used to set the drive current values for each color as a function of temperature. The compensation algorithm may be adapted to assume that LEDs of a given color do not exhibit significant differences in temperature sensitivity. As a result, each lamp need not be characterized thermally but rather may depend on the theoretical and empirically determined temperature relationships in the algorithm.

(37) In a particular embodiment as shown in FIG. 7, a thermistor 511 and controller 509 are provided on the LED circuit board 130. The thermistor 511 senses the temperature of the board 130 temperature from which the LED temperature can be derived, based on previously determined empirical values. The controller 509 communicates with a power source (not shown) via circuitry 513 and controls the current to the LED responsive to signals from the thermistor 511. The lamp is equipped with a rectifier 516 and a regulator 518 that serves to preserve power quality to the LED.

(38) Further, as discussed above, it is desirous for the lamp to maintain a predetermined light intensity once installed. The lamp shown in FIG. 7 includes an optical sensor 515 that communicates with controller 509. Light from the LED light source 118 illuminates the optical sensor 515 and based on the value obtained from the sensor, the controller 509 controls the intensity of the light.

(39) The electrical power supply for supplying electrical power to the LED of the LED light source 118 is selectively operable to provide an intensity adjustment for the LED as controlled by the controller 509. In an embodiment where multiple LEDs are provided, the electrical power supply can be selectively operable to control the level of power transmitted to each LED independent of the level of power transmitted to the other LEDs. The LED can be configured to have a variable color output. For example, the intensity adjustment can range from 0 to about 2500 FC. The intensity adjustment can be continuous throughout its range of adjustments or, alternatively, can be adjustable at discrete settings within its range of adjustments. Controller 509 in communication with the power supply of the LED light source 118 can control the level of power transmitted to the LED, and thus the output intensity of the light from the lamp. Suitable controllers for use with the present invention are well known in the art and include, but are not limited to, any programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC).

(40) In an alternative embodiment of the invention, a dental operatory lamp used to illuminate an operating area comprises a housing having a front directed toward the operating area and a rear facing away from the operating area. A plurality of light emitting diodes (LEDs) can be included. An adapter configured for receiving at least one non-light emitting diode (non-LED) light source is located within the housing. The at least one non-LED light source may consist of a group of lights that can be selected from, for example, Quartz halogen, tungsten halogen, incandescent, xenon, fluorescent, fiber optics, gas plasma, laser, ultraviolet, and blue light. The at least one non-LED light source may also include the group of lights selected from, for example, dental curing light, oral cancer screening light, decay detection (cavities and caries) blood detection sterilization and tooth whitening light.

(41) A particular embodiment of the invention includes a dental operatory lamp used to illuminate an operating area having a housing with a front directed toward the operating area and a rear away from the operating area. The LED light source 118 is positioned with the LED aligned toward predetermined points on the reflective element 116 for directing the light from the LED light source 118 toward the front of the lamp in a pattern that focuses light from the lamp to a central area of illumination of high intensity 204, with significantly reduced intensity illumination 202 outside the central area, as shown in FIG. 5. Particular representative patterns of focused light emanating from the dental operatory lamps of the present invention include, for example, a pattern of focused light that can be elliptically shaped and may be about 3 inches by about 6 inches (7.62 cm by about 15.24 cm) in size. In a particular embodiment, the reduced intensity illumination 202 outside the central area of illumination 204 decreases in intensity by 50% of a maximum intensity relative to the central area of illumination of high intensity. The central area of illumination of high intensity 204 can have a pattern size of at least 50 mm by 25 mm. The reduced intensity illumination 202 outside the central area can be configured to decrease in intensity progressively and smoothly relative to the central area of illumination of high intensity. The pattern can be configured to have a brightness of greater than about 20,000 Lux at a focus height of 700 mm from a target. The illumination on the central area of illumination of high intensity 204 at a distance of 60 mm can be configured to be less than about 1200 Lux. Illumination at the maximum level of the dental operating light in the spectral region of 180 nm to 400 nm can be configured to not exceed 0.008 W/m2.

(42) In a preferred embodiment, a rectangular pattern of light is emitted that has an illuminating region with a perimeter possessing a stark contrast in intensity relative to the surrounding non-illuminated area of the rectangular pattern. In a specific example, the non-illuminated area surrounding the illuminated rectangular pattern has at least a 70%, 80% or 90% decrease in intensity compared to the light in the illuminated rectangular pattern.

(43) FIG. 7 shows an embodiment that incorporates a light guide 250 located on the rear end of the LEDs 118 whereby the light guide 250 allows passage of light therethrough according to a predetermined pattern as discussed in the preceding paragraph, and/or serves as an optical filter, as discussed further below. The light guide 250 is shown as being positioned rearward of a lens 209. The light guide 250 and lens 209 may be used together as shown or individually where one or the other is omitted from the lamp 100. The light guide 250 is shown as being able to flip up (shown as 251, dashed lines) when its use is not desired. FIG. 8 shows examples of plate-type light guides 211 having respective apertures 213a-c, which may be implemented as the light guide 250 shown in FIG. 7. Alternatively the light guide 250 takes the form of an adjustable iris which will shape light according to an intended pattern. FIG. 9 shows an example of one such iris 220 having an adjustable aperture 223 that is controlled by lever 221. Those skilled in the art will appreciate that the iris may be automated thereby avoiding the need for lever 221. Accordingly, a switch can be provided on a convenient location on the lamp to actuate the iris. In addition to the specific examples shown in the drawings, those skilled in the art will appreciate that other types of light guides may be implemented that can shape light according to the desires of the operator, including but not limited to, a LCD/semiconductor panel with areas that can be selectively rendered transparent or opaque. (See for example U.S. Patent Publications 20090207331, 20090230412 and 2005026994 for examples of liquid crystal displays). By impressing a current on the panel you can modulate the generally transparent and generally opaque areas on the panel. This can be used to generate specific patterns of light.

(44) Yet another embodiment of the invention is shown in FIG. 6, wherein a dental operatory lamp used to illuminate an operating area includes a lamp assembly 208 having a front 210 directed toward the operating area and a rear 212 away from the operating area. A reflector module 220 can be located within the lamp assembly 208, and more specifically, can be located at the rear 212 of the lamp assembly 208. A plurality of light emitting diodes (LEDs) can optionally be located in a reflector module 222. Optionally, a light mixing rod (not shown) may be included as part of the reflector module 222 to produce homogenous light from the multiple LEDs of different colors. The lamp assembly 208 can include a curved or faceted interior reflective surface 220. The LEDs can be directed toward the curved or faceted interior reflective surface 220 for directing the light from the LEDs toward the front 210 of the lamp in a pattern that focuses light from the lamp to a central area of illumination of high intensity, with significantly reduced intensity illumination outside the central area. The reduced intensity illumination outside the central area can be configured to decrease in intensity by 50% of a maximum intensity relative to the central area of illumination of high intensity. The reduced intensity illumination outside the central area may be configured to decrease in intensity progressively and smoothly relative to the central area of illumination of high intensity. The light pattern can have a brightness of greater than about 20,000 Lux at a focus height of 700 mm from a target. The illumination on the central area of illumination of high intensity at a distance of 60 mm may be less than about 1200 Lux. The illumination at the maximum level of the dental operating light in the spectral region of 180 nm to 400 nm may be configured to not exceed 0.008 W/m.sup.2.

(45) The lamp 100 of the present invention allows the user to set various chromaticity settings, such as sunlight equivalent D65 or simulated fluorescent lighting for improved dental shade matching. It also allows the addition of thermal, color, or intensity feedback to better maintain light characteristics over the life of the product, and permits adjustment of light intensity independent of color setting. The lamp 100 also is adapted to provide different configurations and forms of color mixing light guides. Specifically, the lamp 100 provides a user selectable mode with reduced irradiance in the near UV and blue wavelengths to allow adequate illumination while not initiating curing of UV-curable dental composites and adhesives. The lamp design can provide longer life through use of LEDs instead of incandescent bulbs and which can be further achieved through use of heat pipes, finned rear housing and fan cooling which maintain low LED temperature even at high currents.

(46) In an alternative embodiment, the light guide 250 also operates as an optical filter and is positioned at the rear-end of the LED light source 118 so as to intercept light from the LED light source 118 as it travels to the reflector 116. The optical filter is designed to eliminate undesired visible wavelengths of light. Moreover, in place of filters or in addition to filters adjacent to the LED light source 118, the lamp may include a shield that is designed to filter light being reflected from the reflector to the treatment area so as to filter out undesired wavelengths of light. FIG. 14 pertains to a front view of a dental lamp embodiment that includes a first shield 240 and second shield 242 adjacent to a front support member 241.

(47) In another embodiment shown in FIG. 10, a reflector 260 is utilized that has a reflecting surface 261 that is generally smooth over the entire extent thereof, is free from facets and reflects the full spectrum of light in visible and infrared wavelengths. The reflector 260 may comprise a coating of aluminum thereon constituting reflecting surface 261. In one example shown in FIG. 11, which is shown as a cross-sectional view of the embodiment in FIG. 10 along the 12-14 axis, the reflector has a concaved structural portion 263 which includes a film having a reflecting surface 262 that is adhered to a structural portion 263 via a self-adhesive backing layer 264. On a back surface of the structural portion 263 are disposed an attachment portion 266 for securing the structural portion 263 to the rear portion of the lamp housing. The structural portion 263 also includes alignment bosses 265 for enabling alignment of the structural portion 263 relative to the treatment area when structural portion 263 is mounted to a housing (see, e.g., 114 of FIG. 1). Alternatively, FIG. 12 shows a cross-sectional view of a different example of the reflector 260 shown in FIG. 10 (along axis 12-14) that is of an integrally formed construction, that includes attachment portion 276 and alignment bosses 275 integrally formed with the reflector 260. In a specific example, the reflector 260 may be formed of aluminum with the front face being polished presenting the reflective surface 261.

(48) FIG. 15 illustrates a side view of an embodiment, generally indicated at 1000, of a light source structure constructed according to principles of the invention. Light source structure 1000 may generally be characterized as a lamp. Lamp 1000 is powered by electricity, and functions to provide illumination to a work area disposed a distance from the lamp front, generally indicated at 1002. Desirably, the work area illuminated by lamp 1000 is shadow-free, and appears relatively uniform in illumination color and intensity. For most applications, the illuminated target work area is considered to have an approximately flat footprint and a depth normal to that footprint. That is, the illuminated region is generally structured to encompass a volume disposed proximate the footprint.

(49) Illustrated lamp 1000 includes attachment structure, generally indicated at 1004, operable to connect lamp 1000 to suspension structure in the work area. Illustrated attach structure 1004 is carried at a back 1006 of lamp 1004, although any convenient arrangement is operable. Typical suspension structure in a dental operatory permits a user to orient the lamp in space operably to aim the light output of lamp 1000 at the desired target area. Certain embodiments of the invention provide a lamp having reduced weight and/or intrusive volume compared to commercially available lamps. Such reduced weight lamps permit a corresponding reduction in mass of the lamp suspension arrangement, thereby increasing ease of manipulation of the lamp to orient its output toward a target.

(50) Lamp 1000 includes a plurality of light modules 1008 disposed in an array and tilted along an arcuate path 1010 to aim their collective light outputs to impinge on a desired target footprint. Illustrated light modules 1008 are sometimes also called reflective modules. One row of modules 1008 is visible in FIG. 1, although any number of such rows may be repeated in a columnar, staggered, or other arrangement in space to form a 3-dimensional lamp body providing the desired luminescent output.

(51) One currently preferred lamp assembly 1000 includes 3 rows forming 5 columns of modules 1008, for a total of 15 modules in the lamp. Such modules 1008 are desirably spaced apart from each other and aimed in harmony to form a shadow-free illumination of a target region. In the context of this disclosure, the term shadow-free means that an object, such as a tool or a user's hand, casts essentially no shadow when placed between the lamp and its illuminated target. It is currently preferred for an output of each module to be shaped to substantially illuminate the entire target footprint. Therefore, the target footprint is fully illuminated by the sum of the outputs of modules 1008. In such an arrangement, an object blocking light emitted by one, or even most, of the modules 1008 still would not cast a shadow on the target footprint. A path along a column between rows may be a straight line, although it is currently preferred that such path (not illustrated, but similar to path 1010) also is arcuate.

(52) In use in an environment such as a dental operatory, it is preferred to provide a front shield 1012 as a protective cover to block migration of dust and contaminated aerosols into the lamp interior. A front surface of such a shield 1012 may be structured to provide an easily cleanable surface, whereby to maintain sterility of the operatory area. In certain embodiments, shield 1012 may incorporate one or more lenses to focus, or otherwise modify, the light output of lamp 1000. Whether or not a focusing lens is provided, a shield made from LEXAN, or other similar optically useful and formable material, desirably is provided to completely encase the front of a dental lamp to resist contamination of, and to facilitate cleaning of, the lamp. Illustrated shield 1012 is injection molded, and includes focusing lenses for each of the modules 1008 in a unitary part. Desirably, shield 1012, or a portion of lamp housing 1014, is hinged, or otherwise openable by a user, to provide access to the interior of lamp 1000 for maintenance or replacement of a light generating element.

(53) With reference to FIG. 16, an LED 1018 emits light indicated by a plurality of rays 1020. An operable LED includes a 3 watt LED such as that sold by Lumileds Lighting US, LLC under the Brand name Luxeon, part number LXHL-LW3C.

(54) Typically, a reflective element, generally indicated at 1022, is provided to direct the LED's light output toward a target. A focusing lens 1024 may be included in an arrangement effective to collimate rays 1020, and further direct them to an illuminated area indicated at 1026. In certain embodiments of the invention, area 1026 corresponds to the target footprint of the lamp 1000. In such case, it is desired that the illumination emitted from each module 1008 is substantially uniform over area 1026. Certain rays 1028 may be emitted in a direction other than desired for impingement on area 1026. Such rays 1028 are characterized as stray light. As indicated by the illustrated collection of rays 1020, area 1026 sometimes has a higher intensity of illumination at its center, and may fade to a decreased intensity near its perimeter. In another embodiment, the LED 1018, mirror 1022, and all associated optics are arranged in harmony to produce a substantially uniform intensity over its illuminated footprint at a selected focal distance.

(55) Another exemplary light module 1008 is illustrated in FIG. 17. Housing 1032 of illustrated module 1008 includes a portion that forms a component stray light tube 1034. An interior surface 1036 of tube 1034 may be reflective, but desirably is arranged to resist reflection of incident stray light rays 1028 to reduce emission of such stray rays outside the target footprint. A preferred stray light tube 1034 provides a black, or essentially light absorbing, surface 1036 to resist reflection of stray light rays 1028. It is within contemplation for a stray light tube 1034 to be formed as a distinct component. However, including the stray light tube as a portion of the housing 1032 reduces part count and cost, and simplifies assembly of a lamp 1000.

(56) LED 1018 is typically mounted with respect to housing 1032 by a conveniently structured foundation 1038. Desirably, foundation 1038 is structured to provide simple and rapid installation and removal of LED 1018, and includes connection structure for the electricity supplied to the LED. It is further desirable for foundation 1038 to be formed from a material capable of conducting heat. Advantageously, foundation 1038 and housing 1032 may be structured and arranged to dissipate any heat generated by LED 1018 in a direction away from the front of the lamp 1000.

(57) Lens 1044 may be arranged to disperse, focus, collimate, color, or otherwise modify a characteristic of light 1020 passing therethrough. Alternatively, or in addition, lens 1044 may be configured as a protective shield for a module 1008, or lamp 1000. In certain cases, a collimating lens may be disposed in the space 1046 located between LED 1018 and a distal end 1048 of module 1008. Desirably, such collimating lens is placed in proximity to the discharge opening of the parabolic reflector 1022 to reduce a length of the light module 1008. In a currently preferred embodiment of lamp 1000, modules 1008 are about 2 inches in length, and approximate the size in a thickness direction of the lamp 1000.

(58) FIGS. 18-20 illustrate configurations of collimating lenses of use in certain embodiments constructed according to principles of the invention. Such lenses typically are structured to direct the LED's light output toward a target, and permit formation of lamp 1000 in a compact form factor. A pair of operable collimating lenses, configured as TIR lenses, is illustrated in FIGS. 18-20. The first collimating TIR lens 1052 (<4.5 deg. FWHM) is illustrated in end and section views in FIGS. 4 and 5, respectively. The second TIR lens (<2 deg. FWHM), illustrated in cross-section in FIG. 6 and is generally indicated at 1054. Such lenses permit a reduction in length of the stray light tube or equivalent portion of a housing 1032.

(59) Although the foregoing description contains many specifics, these are not to be construed as limiting the scope of the present invention, but merely as providing certain representative embodiments. Similarly, other embodiments of the invention can be devised which do not depart from the spirit or scope of the present invention. The scope of the invention is, therefore, indicated and limited only by the appended claims and their legal equivalents, rather than by the foregoing description. All additions, deletions, and modifications to the invention, as disclosed herein, which fall within the meaning and scope of the claims, are encompassed by the present invention. The disclosures of any references cited herein are incorporated in their entirety to the extent not inconsistent with the teachings herein.