Abstract:
A substrate curing system wherein a single LED generates light having a maximum peak wavelength of 377 nm and wherein the generated light is directed to the proximal end of a liquid light guide, the light output from the distal end of the light guide being directed to the surface of the substrate.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a device for curing photosensitive materials utilizing light generated by light emitting diodes and directed to the material by using light guide. 
         [0003]    2. Description of the Prior Art 
         [0004]    U.S. Pat. No. 7,802,910, issued on Sep. 28, 2010 in the name of Kirk A. Middlemass et al, discloses a light guide exposure device comprising light emitting diodes arranged in an array and a flexible light guide having a proximal end and a distal end; the proximal end defining a proximal end diameter. The array is positioned in substantial alignment with the light guide proximal end to direct substantially all of the light from the array to the proximal end. There is no optical element between the light emitting diodes and the proximal end. 
         [0005]    Although the LED array disclosed in the &#39;910 patent emit non-collimated light at a maximum wavelength in the range from about 360 nm to about 420 nm, the commercial version of the device utilizes an LED array that produces a peak output wavelength of approximately 390 nm. This wavelength contains a significant amount of infra-red radiation which typically generates significant heat into the material being cured. In addition, the &#39;910 system operates without an optical element between the LED array and the light guide purportedly to avoid reduced transmittance to the light guide 
         [0006]    U.S. Publication No. 2004/0152038 to Kumagai et al, published on Aug. 5, 2004 discloses a light irradiation apparatus for a dental photo polymerization composite resin which can polymerize and cure the dental photo polymerization composite resin with a structure such that there are arranged a blue ray radiation LED having luminous wavelengths peaked at a wavelength between 450 nm and 490 nm, and a near ultraviolet rays and/or violet rays radiation LED having luminous wavelengths peaked at a wavelength between 370 nm and 410 n,. A circuit changing switch simultaneously turns on these two kinds of LEDs and turns on only the near ultraviolet rays and/or violet rays radiation LED. An optical elements is positioned between the LED&#39;s and the light guide. 
         [0007]    Although the prior art discloses systems for curing a substrate using LEDs, they are typically more costly and less efficient than what is commercially desirable. 
         [0008]    What is desired is to provide a LED based curing device that is more efficient and less expensive than prior art curing devices. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides a device for curing photosensitive materials using a single LED device generating a wavelength peaked at 377 nm, a liquid light guide having proximal and distal ends, and an optical element positioned between the LED and the proximal end of the light guide. 
         [0010]    The device more particularly, comprises an axial cooling fan that covers a metal heatsink, a single monolithic LED generating a peak wavelength in the range between 365 and 390 nm, a thermistor, a lens optical cover, a liquid light guide holder and a liquid light guide positioned within said holder and a lock to secure the light guide within the holder. 
         [0011]    The LED produces illumination having a minimum amount of infra-red, and means are provided for controlling the substrate curing time and adjusting the intensity of the output illumination from 0% to 100%. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0012]    For a better understanding of the present invention as well as other objects and further features thereof, reference is made to the following description which is to be read in conjunction with the accompanying drawing therein: 
           [0013]      FIG. 1  illustrates a partial perspective view of the curing system of the present invention; 
           [0014]      FIG. 2  is an assembly view of the device shown in  FIG. 1 ; and 
           [0015]      FIG. 3  is a flowchart illustrating the operation of the curing system of the present invention. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0016]    Referring now to  FIGS. 1 and 2 , curing system  10  comprises a DC axial fan  12  comprising intake and exhaust sections is mounted to one surface of metal (preferably aluminum heatsink  14 , a single monolithic LED  16  mounted to surface  18  of heatsink  14 , an optical lens cover  22  being positioned over LED  16 . A light guide holder  24  is secured to surface  18  of heatsink  14  via a plurality of fasteners (not shown). A microswitch interlock  26  is positioned within aperture  28  formed in holder  24  and detects whether or not a light guide is inserted into holder  24 ; if a light guide is not inserted, the LED will be prevented from turning on for safety reasons. A friction lock screw  30  is inserted into threaded aperture  32  formed in holder  24  to secure light guide  34  therein in a manner whereby the proximal end  36  of guide  34  is positioned adjacent the emitting surface of LED  16 . 
         [0017]    Thermistor  7 , attached to LED  16 , is used in a voltage divider connected to the microchip  20 , the microchip  20  using the thermistor to calculate the temperature of the LED  16 . The microchip turns fan  12  on/off at certain temperatures and also includes an overheat failsafe to turn off LED  16 . 
         [0018]    Prongs  19  and  21  are the cathode and anode terminals, respectively, of LED  16  and a DC voltage (approximately 6 volts) is applied when the LED is energized. A large current (approximately 20 amps) is generated which produces the ultraviolet light. 
         [0019]    The main system components set forth hereinabove which have been successfully utilized in the system of the present invention are furnished by the following vendors: 
         [0000]    
       
         
               
               
               
             
               
             
               
               
               
             
           
               
                   
               
               
                   
                 Part/Model No. 
                 Manufacturer 
               
               
                   
               
             
             
               
                 DC Axial fan 12 
                 74K4027 
                 Newmark Electronics 
               
               
                 LED 16 
                 CBT-120UV-375 
                 Luminus Devices, Inc. 
               
             
          
           
               
                 (mounting plate 20 incorporates as a single unit LED 16, optical lens  
               
               
                 cover 22 and thermistor 17). 
               
             
          
           
               
                 Light guide holder 24 
                 15B1028 
                 American Ultraviolet Co. 
               
               
                 Light guide 34 
                 Series 300 
                 Lumatec 
               
               
                   
               
             
          
         
       
     
         [0020]    The liquid light guide preferably used in device  10  does not have any fibers, but is constructed of epoxy with liquid inside and solid quartz tips at both the proximal and distal ends. 
         [0021]    Device  10  also provides enhanced cooling since cooling fan  12  covers substantially the entire back surface of heat sink  14 . 
         [0022]    The power requirements of device  10  is 90-260 VAC, 50/60 Hz which is furnished to fan  12 ; the VAC is also connected to DC and applied to LED  16  and LED  16 , LED  16  being activated by a footswitch (not shown). The footswitch directly turns LED  16  on/off in the continuous and manual modes, the functions being controlled through the microchip  20 . A digital timer and meter (not shown) are integrated into the microchip  20  and enable a user to determine how long LED  16  will remain on or off per cycle. 
         [0023]    Means are also provided to adjust the light output intensity from 0% (off) to 100% (full on). A current regulation circuit board (not shown) is designed around an integrated circuit and limits the current going to LED  16  based on the value of an attached adjustable potentiometer. At the minimum value of the potentionmeter ther is no current; at the maximum setting, 20 amps of current is provided. The light outside is directly related to the current driver through LED  16 . 
         [0024]    A control board has a microprocessor mounted thereto (not shown), the microprocessor controlling when LED  16  is on/off, when the fan is on/off, user input and output and associated safety systems. The microprocessor also provides an on/off signal to the current regulation circuit board. A microprocessor that has been successfully utilized is one sold by Microchip Technology, Part No. PIC 16F877-04L. 
         [0025]      FIG. 3  illustrates, in a flowchart format, how system  10  operates. In particular, when system  10  is ready (block  50 ), an OK button (block  52 ) is pressed to initially display how many hours LED  16  has been on and the user then chooses the system mode of operation (block  54 ), either the manual (block  56 ), continuous (block  58 ) or cycle (block  60 ) mode. The mode is selected by the user by pressing footswitch  62 . If the cycle mode is selected (blocks  62 ,  64 ), LED  16  cycles on/off for the durations chosen by the user and the desired number of cycles. In the manual and continuous modes, LED  16  is turned on (blocks  66 ,  68 ) by the footswitch; in the manual mode, LED  16  is turned off by releasing the footswitch (block  70 ) and in the continuous mode, the footswitch is pressed after initially being released which then turns off LED  16  (block  72 ). In the cycle mode, LED  16  is turned off when the cycling is completed and cancelled by the footswitch or pressing the OK button. After LED  16  is turned off, the system is ready for the next operation (block  74 ). 
         [0026]    A number of diagnostic checks are performed when system  10  is running (block  76 ). These include insuring that thermistor  7  is functioning (block  78 ), that the temperatures are high enough to turn on fan  12 , whether LED  16  is overheating (block  80 ) and whether electrical problems have been detected (block  82 ). A detected error (block  84 ) is displayed on a monitor and system  10  is disabled (block  86 ). 
         [0027]    While the invention has been described with reference to its preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its essential teachings.