Abstract:
An ultraviolet lamp system for irradiating a substrate includes a magnetron and a memory physically attached to the magnetron. An electrodeless lamp is configured to emit ultraviolet light when excited by microwave energy generated from the magnetron. Main control circuitry is operable to read and write operational data associated with the magnetron to the memory. The ultraviolet lamp system is operated by generating microwave energy from the magnetron. A plasma within an electrodeless lamp is excited with the microwave energy to emit ultraviolet light. Operational data associated with the magnetron is tracked and written to the memory associated with the magnetron.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to ultraviolet lamp systems and, more particularly, to maintaining historical operational data for ultraviolet lamps. 
       BACKGROUND OF THE INVENTION 
       [0002]    Ultraviolet (“UV”) lamp systems are commonly used for heating and curing materials such as adhesives, sealants, inks, and coatings. Ultraviolet lamp systems operate by exciting an electrodeless plasma lamp with microwave energy. The electrodeless lamp is mounted within a metallic microwave cavity or chamber. One or more microwave generators, such as magnetrons, are coupled via waveguides with the interior of the microwave chamber. The magnetrons supply microwave energy to initiate and sustain a plasma from a gas mixture enclosed in the electrodeless lamp. The plasma emits a characteristic spectrum of electromagnetic radiation strongly weighted with spectral lines or photons having ultraviolet and infrared wavelengths. 
         [0003]    Magnetrons used in the UV lamp systems are consumable items with their life determined by a number of factors, including total hours of operation, number of starts, time in a standby mode, power level, as well as other conditions. Predicting when a magnetron will fail or reach the end of its life requires knowledge of its operation history. In addition to providing a better prediction of end of life, the history can also be used to verify warranty claims, provide better information for failure analysis, and improve magnetron life by adjusting the operating parameters. 
       SUMMARY OF THE INVENTION 
       [0004]    An ultraviolet lamp system is provided which includes a magnetron and a memory physically attached to the magnetron. An electrodeless lamp is configured to emit ultraviolet light when excited by microwave energy generated from the magnetron. Main control circuitry in the lamp system is operable to read and write operational data associated with the magnetron to the memory. The memory includes a non-volatile computer memory chip attached to the magnetron in some embodiments. 
         [0005]    In other embodiments, the ultraviolet lamp system includes an intermediate control circuit in electrical communication with the main control circuitry and in electrical communication with the memory. The main control circuitry is configured to track operational data for the magnetron and communicate with the intermediate control circuit to provide tracked operational data thereto. The intermediate control circuit is operable to read and write operational data to and from the memory. The intermediate control circuit communicates with the main control circuitry using a CAN protocol. 
         [0006]    In another embodiment, the ultraviolet lamp system includes a second magnetron. The main control circuitry for this embodiment is operable to write operational data associated with the first magnetron and the second magnetron to the memory. 
         [0007]    Operational data includes filament use hours, actual hours under power, number of power on/off cycles, time in a standby mode, initial power level of the magnetron, output power level of the magnetron, and combinations thereof. 
         [0008]    The ultraviolet lamp system is operated by generating microwave energy from the magnetron, which excites a plasma within an electrodeless lamp to emit ultraviolet light. Operational data associated with the magnetron is tracked and written to a memory associated with the magnetron. The operational data associated with the magnetron may also be read from the memory. 
         [0009]    In some embodiments, an operating parameter of the magnetron is adjusted based on the operational data read from the memory. In other embodiments an end of life for the magnetron is predicted from the operational data read from the memory and a recommendation that the magnetron be replaced is made in response to the magnetron being near the predicted end of life. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention. 
           [0011]      FIG. 1  is a block diagram of an ultraviolet lamp system including a magnetron with a memory. 
           [0012]      FIG. 2 . is a block diagram of an alternate embodiment of the ultraviolet lamp system including a magnetron with a memory. 
           [0013]      FIG. 3  is a block diagram of an embodiment of the ultraviolet lamp system including two magnetrons with a memory. 
           [0014]      FIG. 4  is a flowchart showing a method to store operational data in the memory of the ultraviolet lamp systems of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Referring now to the drawings,  FIG. 1  is a block diagram of an ultraviolet lamp system  10  that relies upon excitation of an electrodeless lamp  12  with microwave energy. The electrodeless lamp  12  is mounted within a metallic microwave chamber  14 . A magnetron  16  is coupled via waveguide  18  with the interior of the microwave chamber  14 . The magnetron  16  supplies microwave energy to the electrodeless lamp  12  in order to generate ultraviolet light  20 . The ultraviolet light  20  is directed from the microwave chamber  14  through a chamber outlet  22  to an external location through a fine-meshed metal screen  24  which covers the chamber outlet  22  and is capable of blocking emission of microwave energy, while allowing the ultraviolet light  20  to be transmitted outside the microwave chamber  14 . 
         [0016]    A memory  26  is physically attached to the magnetron  16  and is configured to store operational data related to the magnetron  16 . The operational data associated with the ultraviolet lamp system  10  is generally tracked and stored by main control circuitry  28 , which is typically associated with the power supply. The main control circuitry  28 , however, does not generally track when magnetrons  16  are replaced, and thus any operational data associated with a specific magnetron  16  may be lost. The memory  26  is in electrical communication with the main control circuitry  28 . The main control circuitry  28  is operable to periodically write operational data related to the magnetron  16  to provide a history of the use of the magnetron  16 . Because the memory  26  is attached to the magnetron  16 , this history is retained with the magnetron  16 . The magnetron history may then be used in conjunction with, for example, warranty and failure matters of the magnetron  16 . 
         [0017]    In an alternate embodiment of the ultraviolet lamp system  40  illustrated in  FIG. 2 , an intermediate control circuit  42  may be used in conjunction with the memory  26  on the magnetron  16 . The intermediate control circuit  42  is in electrical communication with both the main control circuitry  28  and the memory on the magnetron  16 . In addition to facilitating the connection of the main control circuitry  28  to the memory  26 , the intermediate control circuitry  42  may also be operable to track additional operational parameters not currently tracked by the main control circuitry  28  or may track operational parameters in place of the main control circuitry  28 . 
         [0018]    The main control circuitry  28  is located in the power supply enclosure (not shown), which is connected to the lamp head by a multi-conductor cable. The multi-conductor cable may be up to approximately 100 feet in length. To minimize the number of conductors in the cable and to ensure reliable signals, the intermediate control circuit  42  and main control circuitry  28  communicate using a digital link  44  such as the CAN protocol, although other communications protocols may be used for other embodiments. All of the operational parameters from the main control circuitry  28  are sent over the digital link  44  to the intermediate control circuit  42 , which then writes them to the memory  26  on the magnetron  16 . 
         [0019]    In some embodiments, as described above, tracking the operational data may be divided between the main control circuitry  28  and the intermediate control circuit  42 , where, for example, the main control circuitry  28  tracks the actual number of filament use hours, while the intermediate control circuit  42  tracks the output power levels of the magnetron  16 . The main control circuitry  28  would then communicate the tracked filament use hours to the intermediate control circuit  42 , which in turn would store the filament use hours in the memory  26 . 
         [0020]    Other embodiments of the ultraviolet lamp system  10  may include additional magnetrons and potentially additional memories attached to those magnetrons. For example, an embodiment of the ultraviolet lamp system  50  in  FIG. 3  is a system requiring a pair of magnetrons  52 ,  54 . These magnetrons  52 ,  54  are coupled via waveguides  56 ,  58  to the interior of the chamber  14 . A memory  60  is physically attached to one of the two magnetrons  52 ,  54  and tracks the operational data for both magnetrons  52 ,  54 . A single memory  60  may be used for this embodiment, because the magnetrons  52 ,  54  will always be installed and/or replaced in pairs. In still other embodiments having multiple magnetrons, each magnetron may have its own memory. 
         [0021]    Referring again to  FIG. 1 , the historical data stored in the memory  26  of the magnetron  16  may be used for multiple purposes. For example, the end of life of a magnetron  16  is fairly predictable if the number of hours of operation of the magnetron  16  is known. This historical data could be used to prevent a failure by predicting the end of life and then displaying a message to an operator on the power supply display recommending that the magnetron  16  should be replaced before a failure occurs. Additionally, if the ultraviolet lamp system  10  predicts that the magnetron  16  is near the end of its life, the ultraviolet lamp system  10  may increase the current to the filament, for example, to assist in prolonging the life of the magnetron  16 . 
         [0022]    Similarly, data could be obtained and analyzed to determine the number of hours that the magnetron  16  is in use, either actively or in a stand-by mode. In a stand-by mode, the magnetron&#39;s filaments are heated, but the lamp  12  is not lit. Other data that may be useful to both the lamp system owner and manufacturer could include the number of hours the filament is heated, the number of on/off power cycles, initial power level of the magnetron  16 , and output power levels of the magnetron  16 . 
         [0023]    For example, the above-mentioned data can be used to validate warranty claims or issues. If a magnetron is returned after a few hundred hours of use for prematurely failing, the data stored in the memory  26  associated with the magnetron  16  can be analyzed to determine the cause of the failure. Based on the data, the failure may be a genuine failure of the magnetron  16  and a warranty would cover the replacement. Alternatively, the magnetron  16  may have been left in standby (filament power applied) for thousands of hours, causing the magnetron  16  to fail because it reached its end of life, not because of an inherent problem with the device. 
         [0024]    The memory  26  could also be used in conjunction with a new magnetron  16  by initially storing an output power level associated with the new magnetron when it is shipped to a customer. Specifications on the output power for some magnetrons range from approximately 2.8 kW to approximately 3.2 kW. The output power data stored in the memory  26  can be used to adjust the power settings when the magnetron  16  is installed so that 100% output power would be equivalent the lower limit of approximately 2.8 kW. For example, in the two-magnetron configuration of the ultraviolet lamp system  50  in  FIG. 3 , magnetron  52  may have an output power rating of 2.8 kW and magnetron  54  may have an output power rating of 3.1 kW. The main control circuitry  26  would read the output power ratings of the two magnetrons  52 ,  54  from the memory  60  and adjust the input power of magnetron  54  such that its maximum output would not exceed the 2.8 kW of magnetron  52 . 
         [0025]    Because the magnetrons  52 ,  54  are consumable items, they will be replaced many times over the useful life of the lamp system  50 . For some critical applications, the UV intensity and exposure time are determined during process development of the application. Deviation in the UV intensity (which is proportional to the output power of the magnetron) can cause the process to fail to meet specifications. This typically would occur each time the pair of magnetrons  52 ,  54  is replaced, requiring the “process” to be manually adjusted to obtain the desired results. By reading the operational data containing the output power characteristics of the magnetrons  52 ,  54  from the memory  60 , the main control circuitry  28  can automatically adjust the maximum output power to the magnetrons  52 ,  54  to approximately 2.8 kW to continue to produce consistent output levels of the ultraviolet lamp system  50 , eliminating the need for any manual re-adjustments to the “process”. 
         [0026]    Referring now to the flowchart in  FIG. 4 , the operational data associated with the magnetron is tracked in block  100 . The operational data is periodically updated in block  102 , and then written to the memory in block  104 . Once the operational data is stored in the memory, it can be read in block  106  to be used either during the operation of the lamp system, in conjunction with warranty claims as described above, or for other purposes. If the operational data is read during the operation of the lamp, it can be used to predict or adjust other operational parameters in block  108 , such as predicting the end of life of the magnetron or adjusting the filament current of the magnetron as described above. 
         [0027]    While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicants&#39; general inventive concept.