Patent Application
20140138550
The invention relates generally to ultraviolet (UV) curing lamp assemblies, and more particularly, to a UV curing lamp assembly that includes on-board intelligence for automated inventory and monitoring of internal parts.
Radiant energy is used in a variety of manufacturing processes to treat surfaces, films, and coatings applied to a wide range of materials. Specific processes include, but are not limited to, curing (i.e., fixing, polymerization), oxidation, purification, and disinfection. Processes employing radiant energy to polymerize or effect a desired chemical change are rapid and often less expensive compared to a thermal treatment. The radiation can also be localized to control surface processes and allow preferential curing only where the radiation is applied. Curing can also be localized within the coating or thin film to interfacial regions or in the bulk of the coating or thin film. Control of the curing process is achieved through selection of the radiation source type, physical properties (for example, spectral characteristics), spatial and temporal variation of the radiation, and curing chemistry (for example, coating composition).
A variety of radiation sources are used for curing, fixing, polymerization, oxidation, purification, or disinfections applications. Examples of such sources include, but are not limited to, photon, electron, or ion beam sources. Typical photon sources include, but are not limited to, arc lamps, incandescent lamps, electrodeless lamps and a variety of electronic and solid-state sources (i.e., lasers). Conventional arc type UV lamp systems and microwave-driven UV lamp systems use tubular bulb envelopes made of fused quartz glass or fused silica.
Referring now to
A work piece tube 30 of circular cross-section is received in circular openings 28 in the end reflectors 26. The center of the openings 28 and the axis of the work piece tube 30 are typically located at the external focus of the half-ellipse formed by the primary reflector 16 (i.e., the foci of the half-ellipse formed by the secondary reflector 25). The work piece tube 28 and the secondary reflector 25 extend linearly along an axis in a direction moving out of the page (not shown).
In operation, gas in the light source 20 is excited to a plasma state by a source of radio frequency (RF) radiation, such as a magnetron 29 located in the irradiator 12. The atoms of the excited gas in the light source 20 return to a lower energy state, thereby emitting ultraviolet light (UV). Ultraviolet light rays 38 radiate from the light source 20 in all directions, striking the inner surfaces of the primary reflector 16, the secondary reflector 25, and the end reflectors 24, 26. Most of the ultraviolet light rays 38 are reflected toward the central axis of the work piece tube 30. The light source 20 and reflector design are optimized to produce the maximum peak light intensity (lamp irradiance) at a surface of a work product (also propagating linearly out of the page) placed inside the work piece tube 30.
Unfortunately, the currently employed cables 44, 46 between the external power supply 40 and the irradiator 12 have a number of drawbacks. The cables 44, 46 have a limited range due to losses in the cable. Current irradiators 12 are not user friendly for product upgrading, standardizing and compatibility. For example, certain critical monitorable parameter, including UV power, temperature, air pressure, and part type require the installation of additional sensors inside the irradiator 12. The cables 44, 46 do not permit changes necessary to accommodate remote monitoring of the above-cited parameter because of limited I/O and significant tethering that requires close proximity of the external power supply 40 to the irradiator 12.
Current irradiators 12 do not permit the monitoring of UV output power that emanates from the UV-emitting bulb 20. Each UV-emitting bulb 20 is not identical in its UV output power. There are certain UV curing applications where multiple UV-emitting bulbs 20 are mounted adjacent to one another. Manual adjustments are required to lower or increase the voltage to equalize variations in UV output power from lamp to lamp. Therefore, it would be desirable to permit automatic monitoring and adjustment of UV output power.
Currently employed pressure switches (not shown) do not permit real time monitoring of air pressure inside the irradiator 12. The rate of flow of air inside the irradiator 12 is critical to the life of the UV-emitting bulb 20 and the magnetron 29. It is therefore desirable to install a monitorable pressure sensor that can transmit real time data back to a controller. Further, a monitorable pressure sensor can be integrated with a “smart blower” to automatically manage airflow and changing of speed of the “smart blower” based on data received from the monitorable pressure sensor.
Accordingly, what would be desirable, but has not yet been provided, is a microprocessor-controlled UV curing irradiator for monitoring internal sensors for performance parameters, part lifetime, and inventory control without necessitating major changes to a high voltage power supply.
The above-described problems are addressed and a technical solution is achieved in the art by providing an “intelligent” irradiator that permits automated monitoring of performance parameters, part lifetime, and inventory control of internal parts. The irradiator includes an on lamp microprocessor. The on lamp microprocessor may be configured to recognize internal parts, record accumulated working time for each part, sample and process data from the plurality of sensors, and communicate with a master computer processor located within an external “intelligent” power supply via a serial bus cable.
According to an embodiment of the present invention, the on lamp microprocessor is configured to communicate with a plurality of intelligent markers (IMs) associated with one or more internal magnetrons and an internal primary reflector. The intelligent markers may comprise at least one of a radio frequency identification tag (RFID) or a small footprint microcontroller adhered to each part to be monitored. The on lamp microprocessor communicates with the IMs via standard serial links such as a serial peripheral interface (SPI) bus. The on lamp microprocessor also communicates with a plurality of analog/digital sensors that includes one or more temperature detectors operating as a bulb recognizer (BR), an air pressure sensor for detecting a rate of air flow from an internal fan within the irradiator, a UV power sensor, and an RF detector for microwave leaking detection.
The “intelligent” irradiator communicates with an “intelligent” external power supply modified to include a master computer processor for controlling the irradiator and reading data processes by the on lamp microprocessor over a digital serial communication bus for communication between the irradiator and the power supply using an inexpensive standard communication protocol (e.g., CAN bus).
The present invention may be more readily understood from the detailed description of an exemplary embodiment presented below considered in conjunction with the attached drawings and in which like reference numerals refer to similar elements and in which:
It is to be understood that the attached drawings are for purposes of illustrating the concepts of the invention and may not be to scale.
According to an embodiment of the present invention, on lamp microprocessor 80 may be configured to: (1) recognize parts, including one or two magnetrons 29 associated with the intelligent markers IM1 and IM2, respectively, the primary reflector 16 associated with the intelligent marker IM3, and, the microwave-powered, UV-emitting bulb 20 (i.e., the light source 20) associated with the bulb recognizer (BR); (2) record accumulated working time for each part, which is storable in non-volatile memory (i.e., the computer-readable storage medium 82); (3) sample and process data from the plurality of sensors 56a-56n, which may include, but are not limited to, one or more temperature sensors 56a operating as the bulb recognizer (BR) for detecting the type of the UV-emitting bulb 20, an air pressure sensor 56b for detecting the rate of air flow from an internal fan (not shown) within the irradiator 50, a photo detector 56c for measuring UV light output from the irradiator 50, and other optional sensors such as a filament current sensor and an HV cable interlock (not shown); and (4) communicate with the master computer processor 64 within external power supply 60 via the serial bus cable 63.
Parts may be recognized by analog/digital means via the plurality of sensors 56a-56n over the sensor port 86 (e.g., the bulb recognizer (BR)) and digital means via the intelligent markers 54a-54n (labeled IM1-IMn) over the serial bus port 90. As used herein, an intelligent marker (IM) refers to, but is not limited to, a semiconductor chip that permanently maintains manufacturing information, such as, but not limited to, a produced date, a part number, and a life time limit. The irradiator 50 may include, but is not limited to, one or both of two types of IMs: a radio frequency identification tag (RFID) or a small footprint microcontroller. An IM may be permanently adhered to a part using epoxy or other adhesive.
When an IM is an RFID tag, the RFID tag is configured to communicate wirelessly via radio frequency (RF) waves for exchanging data with a reader (not shown). Several types of RFID products are known, such as the Texas Instruments' RI-103-114A-01 and ATMEL's AT88SCRF-ADK2. RFID tags have been employed in such diverse applications as driver licenses, passports, and bus, metro and, highway passes. Current RFID tag designs, such as the RFID tag 92 shown in
An alternative solution for implementing an IM is to employ a microcontroller with a very small footprint, such as the 8-bit PIC10F222T-I/OT microcontroller produced by Microchip Technology or the ATTINY10-TSHR produced by Atmel. The small footprint microcontroller type IM may be connected to the on lamp microprocessor board 52 via 3 to 5 wires. In such circumstances, the on lamp microprocessor 80 communicates with the small footprint microcontroller via the serial bus 88 over the serial bus port 90 to access information pre-written by the manufacturer of the part to be tracked.
A major difficulty in implementing an IM for use as a recognizer (BR) is the high operating temperature of the UV-emitting bulb 20. A fully-operating UV-emitting bulb 20 has a temperature in the range of about 700° C.-900° C., which may damage all but a few expensive military specification microcontrollers. In addition, the IM would be exposed to high levels of UV and microwave radiation. Therefore, adhering an inexpensive semiconductor-based IM to the UV-emitting bulb 20 is prohibitive.
An alternative implementation of a BR may take advantage of a characteristic of microwave-powered bulbs manufactured by Fusion UV Systems, Inc. of Gaithersburg, Md. Such bulbs contain a trace amount of an isotope of the radioactive element Krypton (i.e., “Kr 85”), which decays to non-radioactive byproducts after a predetermined amount of time (i.e., just enough to permit the microwave-powered bulb to reach operating temperature). If an irradiator does not employ Kr 85, the time for the microwave-powered bulb to ramp up to full operating temperature is significantly extended, resulting in potential harmful effects to the magnetron 29. In such circumstances, a sensor may be employed that recognizes the presence of Kr 85. A sensor that detects radiation emitted by Kr 85 may be remotely mounted at a safe distance from the UV-emitting bulb 20 within the irradiator 50. A radiation detector-based sensor may include, but is not limited to, a small Geiger counter, a CMOS or CCD imager that is operable with the on lamp microprocessor 80 to recognize the emission spectrum of Kr 85, or in a preferred embodiment, a PIN diode used as a radiation detector, such as the UM9441 or UM9442 manufactured by Microsemi Corp.
Still another approach for implementing a BR is to analyze the behavior of the UV-emitting bulb 20 in the presence of Krypton. During bulb ignition, the emission spectrum from the UV-emitting bulb 20 has a characteristic optical transition wavelength specific to Krypton. This optical transition wavelength will only be emitted when the UV-emitting bulb 20 is first ignited, when mercury pressure is very low. A photo detector may then be employed as the BR to detect the brief Krypton emission during ignition.
Certain internal parts of the irradiator 50 monitored by the IMs 54a-54n are intended to be disposable, such as, but not limited to, the UV-emitting bulb 20 and the primary reflector 16. All disposable parts inside the irradiator 50 may have pre-written information stored in the IMs 54a-54n as part of an inventory tracking system. Stored information may include, but is not limited to, a part number, a manufacturing date, and a life time limit. The data representing this information may be communicated from the IMs 54a-54n to the on lamp microprocessor 80 and then to the master computer processor 64 in the external power supply 60.
In operation, upon initial installation and any subsequent installation of each of the disposable parts, information stored in the IMs 54a-54n may be read by the on lamp microprocessor 80 over the serial bus 88. The on lamp microprocessor 80 assigns to each part a part ID. The on lamp microprocessor 80 records a start date and time for each of the monitored parts. The on lamp microprocessor 80 may compare the working time of the part to its expected maximum life time. When the working time approaches or exceeds a pre-established expiration date, the on lamp microprocessor 80 sends a message over serial bus cable 63 to the master computer processor 64 within external power supply 50, and from there to the user via the serial link 70 (e.g., a CAN bus serial link) and/or a network (e.g., the Internet), that it is time to check and/or replace the part. An external monitoring system at the user site may be configured to count and display the working time of each part. Additionally, the on lamp microprocessor 80 may store a life time limit for each part that is 20%-30% greater than the stated manufacturer's life time limit. When the working time exceeds the stored life time limit, the part and/or the irradiator 50 may be disabled by the master computer processor 64 or by shutting down the external power supply 60.
The irradiator 50 is upgradeable without requiring changes to the external power supply 60 or the cables 62, 63. For example, the irradiator 50 may be equipped with an optional non-contact infrared (IR) sensor employed as a temperature sensor. Employing a non-contact temperature sensor avoids damage due to potential overheating of the UV-emitting bulb 20, which may reach temperatures upwards of 1000° C. An exemplary IR sensor suitable for use in the irradiator 50 is a TPD 333/733 thermopile manufactured by Perkin Elmer.
The irradiator 50 may also be equipped with an optional UV sensor for detecting the power level of UV radiation emitted by the UV-emitting bulb 20. A type of UV power sensor suitable for use in the irradiator 50 may include is a UV light power density photodiode. In the prior art irradiator 12, a measured output UV power level (not shown) is used as an aid for manual adjustment of UV light power output. The conventional external power supply 40 of
Conventional irradiators 12 are operable to employ UV-emitting bulbs 20 of different lengths and types. For a particular length and type of the UV-emitting bulb 20, it is necessary for a user to manually employ an external UV light power detector to measure the UV light power emanating from the UV-emitting bulb 20. Employing an on-lamp UV power detector permits automatic adjustment and display of UV power without any manual calibration.
According to an embodiment of the present invention, referring gain to
The irradiator 50 illustrated in
Referring again to
It is to be understood that the exemplary embodiments are merely illustrative of the invention and that many variations of the above-described embodiments may be devised by one skilled in the art without departing from the scope of the invention. It is therefore intended that all such variations be included within the scope of the following claims and their equivalents.
