Patent Number: 044712260
Section: summary

SUMMARY OF THE INVENTION This invention relates generally to radiant energy and more specifically to a radiation source consisting of a portable unit with a radiation shield member. The rapid curing of resin systems by the use of radiant energy within a broad spectral range is well established. The process of polymerization can actually be accomplished by irradiation of several forms of energy of which the most common is probably heat, but the use of ultraviolet energy has particular advantages in that the wavelength of ultraviolet energy permits sharp focus, and the devices for generation of ultraviolet power sufficient for polymerization can be small, have relatively low power consumption and be easily portable. U.S. Pat. No. 4,167,669 by C. R. Panico, for instance, describes an apparatus which pulse activates ultraviolet lamps for the purpose of accelerating the polymerization process. While such devices have been generally available in portable systems with hand held ultraviolet applicators, such as the one shown in U. S. Pat. No. 3,970,856, the relatively low ultraviolet power output of many of the units has resulted in the neglect of safety considerations. However, as the power output range has increased for industrial use, and as the devices have become more generally used in high production situations, accidental exposure risks have increased. Althoush hand held units remain quite satisfactory for many industrial applications, the hazard of the activation of an radiation applicator while it is directed at the operator or some other person in the vicinity is very real and very dangerous. The exposure of the human eye to high intensity ultraviolet radiation can cause severe eye damage and even blindness, and even exposure of skin to the radiation can cause severe burns, actually a "sunburn". It is, therefore, desireable to in some way eliminate the possibility of misdirecting the radiation while still permitting the versatility of hand held application, so that the work area treated by radiation can be easily and quickly changed in a production setting. The present invention accomplishes the restriction of the radiation exposure to a specific work area and prevents accidental exposure of the operator or nearby personnel, but essentially retains the advantages of a highly portable applicator of radiant energy. This is done by the use of a two part system which includes a locator plate to predetermine the area to be treated with radiation and an interlocking radiation head which is activated by a force actuated switch located on the same surface as an aperture for radiation emission. The applicator is accomodated into the locator plate by a tight fitting moulding which seals the radiation leaks and restricts exposure to the area determined by the locator plate, while the force activated switch location assures that the unit will be activated only when the radiation port is mated on a surface. Since the weight of the applicator head is not sufficient to activate the switch, merely placing the unit in the locator plate or on a flat surface will not cause accidental turn-on. To initiate the radiation it is necessary to positively push downward on the applicator while the force activated switch and the radiation port are on a surface. An additional switch can also be installed on the applicator to assure that the applicator is always used in conjunction with the locator plate. This accomplished by the use of a magnetically activated switch located in the applicator head along a surface which is adjacent to the locator plate when the applicator is inserted into the locator plate. The locator plate is then constructed with a magnet at the location which matches the magnetically activated switch when the applicator is properly positioned into the locator plate. The magnetically operated switch, wired in series with the force activated switch, then assures proper insertion into the locator plate before the radiation source can be activated by the force actuated switch. An additional safety feature of the shielded housing is the mechanical lock-out to prevent unintentional activation of the radiation source. For example, the lock-out can consist of a springloaded mechanical bar located to interfere with the movement of the force actuated switch. The initiation of the radiation therefore requires a two step operation which involves both releasing the mechanical lock-out and applying force to the applicator head when it is resting on a surface. This dual action prevents the accidental activation of radiation when, for instance, the applicator is being moved from one work area to another, by the operator accidentally wrapping his hand around the unit and pushing the switch with a finger tip. The specific procedure for operating the unit involves aligning the locator plate with its aperture over the area to be exposed to radiation. With the radiation source power supply plugged into an electric power source and turned on, the applicator head is inserted into the locator plate with its aperture downward, the lock-out bar is released, and hand pressure is applied atop the applicator. This pushes the applicator down against the force activated switch to turn the radiation source on. If the locator plate magnet interlock is being used, the simple operation of properly inserting the applicator into the locator plate operates that switch. The locator plate and the force actuated and magnetic switches whether used independently or together, thus each fulfill a requirement for safe operation of the hand held applicator. The locator plate, which may either be flexible or inflexible, locates the applicator and properly aims the radiation while preventing leakage around the periphery of the applicator. The force actuated switch and its mechanical lock-out bar encourage use only on a flat surface and prevent accidental activation while permitting ease of normal operation, and the magnetically operated switch assures operation only in association with the protective locator plate.