Patent Application
20090196049
This invention relates to lamps and more particularly to PAR lamps.
PAR lamps, in both ceramic and glass versions, provided with a screw base, have been used for many years. The lamps have served both the consumer and industrial markets well. In the glass varieties (usually constructed of a borosilicate glass) stress and thermal expansion have been known to cause glass fractures and failure of the lens adhesive. Ceramic versions have avoided this problem to some degree by employing an aluminum lens retaining ring and a ceramic adhesive; however, this lamp is very sensitive to process changes. The application of the ceramic adhesive is susceptible to curing rate issues, application quantity and oven curing temperatures and times. Even providing the retaining ring with threads failed to solve the problem of retaining the lens, since variations in reflector and lens ring sizes often failed to keep the lens in place. Such failures can cause safety issues because the lamps operate at very high temperatures and, thus, a falling lens (these lamps are often operated in ceiling fixtures) can be extremely hot and create a dangerous situation.
It is, therefore, an object of the invention to obviate the disadvantages of the prior art.
It is another object of the invention to enhance reflector lamps.
Yet another object of the invention is the improvement of lensed lamps.
These objects are accomplished, in one aspect of the invention by a lamp comprising a reflector body that has a forward end wall and an adjacent circular rim. One or more recesses are formed in an outer surface of the rim. A circular metal ring has a radial ledge and a sidewall. The ring encloses a lens that is fitted to the forward end wall and encompasses the circular rim. One or more depressions are formed in the metal ring sidewall and extend into the recesses formed in the circular rim, thereby securely holding the lens in place.
In another aspect of the invention a method of making a lamp comprises the steps of first forming a lamp reflector body. The reflector body includes a reflective cavity and has a forward end wall and an adjacent circular rim containing one or more recesses. A circular lens is formed and then a circular metal ring is formed. The ring has a radial ledge and a sidewall. The radial ledge will retain the lens and the sidewall encompasses the circular rim. After positioning the lens and the circular ring to form an assembly, the sidewall of the ring is deformed into the recesses to lock the ring into position on the body.
In a preferred embodiment of the invention the deformation occurs by placing the assembly on the axis of an axial magnetic field generator and inducing the magnetic field generator to radially press portions of the circular metal ring sidewall into the recesses formed on the circular rim of the body.
This operation firmly locks the ring onto the body and thus retains the lens through time and all thermal excursions to which the lamp may be subjected.
The use of a ceramic adhesive is eliminated and there is no need to pre-form threads on the lamp body and the lens retainer.
For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims taken in conjunction with the above-described drawings.
Referring now the drawings with greater particularity, there is shown in
The lamp body 12 is shown more particularly in
A metal ring 26 (see FIGS. 1 and 5-7) preferably formed of aluminum, has a radial ledge 28 and a sidewall 30. A lens 24 is positioned on the forward end wall 26 of the lamp body 12 and is held in place by the radial ledge 28. One or more depressions 22a are formed with the sidewall 30 and into the recesses 22, thereby retaining the lens 24 on the body 12. Preferably, the number of depressions 22a is equal to the number of recesses 22.
To fabricate the lamp 10, the lens 24 is placed on the forward end wall 16 and the metal ring 26 is placed thereover, the radial ledge 28 retaining the lens, and the sidewall 30 engaging the circular rim 20 and the recesses 22, thus forming an assembly 32. Thereafter, the ring sidewall 30 is deformed to form depressions 22a that extend into the recesses 22, thereby retaining the lens 24 in place. No adhesive is used nor required.
In a preferred embodiment of the invention, the assembly 32 is centered on the axis 34 of an axial magnetic field generator 36, as shown diagrammatically in
Thus there is provided an improved and enhanced lamp that does not have the problems associated with the prior art. The lens is firmly affixed to the lamp body and will not fall off. No adhesive is required to hold the lens in place and assembly operations are easily repeatable and not subject to the variations present in the prior art techniques. Since the technique is performed on the lamp body, it is adaptable to lamps regardless of the light source used within the lamp body, for example, the light source could be a simple incandescent, halogen incandescent, HID or LED.
While there have been shown and described what are at present considered to be the preferred embodiments of the invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of the invention as defined by the appended claims.
