Electrical connectors – Coupling part to receive fluorescent or neon lamp – With provision for axial receipt of lamp contact
Reexamination Certificate
1997-04-23
2003-10-14
Gushi, Ross (Department: 2833)
Electrical connectors
Coupling part to receive fluorescent or neon lamp
With provision for axial receipt of lamp contact
C439S230000
Reexamination Certificate
active
06632100
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
This invention relates to lighting systems, and components and assemblies for lighting systems, such as socket assemblies and lamp insulator assemblies, used in lighting systems. One aspect of an embodiment of the invention relates to fluorescent lamp sockets and mounting arrangements for such sockets, while another aspect relates to fluorescent lamp insulators.
B. Related Art
The use and operation of fluorescent lighting systems are affected by a number of factors. One factor is safety, one purpose being to minimize the possibility of electrical shock to personnel, including customers, maintenance personnel and the like. Another factor is the lighting system dimensions, including the lamp size, size of electrical contacts, and the positioning of electrical contacts. A further factor includes environmental considerations, such as the operating temperature, and the surrounding temperature. Environmental considerations also include humidity, especially where the surrounding temperature may result in moisture condensation or icing. Another consideration under the category of environment includes operating conditions such as vibration, impact, and protection from other mechanical factors. Another factor includes ease of installation, repair and replacement, including interchangeability or variability of parts and lamps in the lighting system. A further consideration is how the lighting system is electrically driven. Each of these factors will be discussed more fully below.
The majority of present lighting systems are electrically driven. Standards have been established for design, certification and approval of most lighting systems for the protection of personnel, such as occupants, customers, installation and repair personnel, as well as others. Such standards include insuring that personnel are not exposed to high, voltage or electric shock during installation or replacement of lighting elements such as lamps and bulbs. For example, most household incandescent bulbs have the hot and neutral contacts positioned relatively close to each other so that installation of the bulb does not produce an exposed live contact. The risk of shock is minimized for the user by grasping the relatively low conductive glass portion of the bulb, and the contacts become live only after the bulb is substantially threaded into the socket. A common design for fluorescent sockets minimizes the possibility of electrical shock by having each end of the lamp inserted into respective sockets and seated or rotated a given amount before electrical contact occurs. This minimizes the possibility of having an exposed live contact. Another design of fluorescent sockets has one socket spring loaded so that the socket can be depressed with one end of the linear lamp inserted into the socket to permit enough spacing for the opposite end to be inserted into its respective socket. However, there is still a possibility that the opposite end of the lamp could be live before it is inserted into its corresponding socket. U-shaped fluorescent lamps and lamps having other shapes significantly different from the traditional linear shapes are comparable in some ways to traditional incandescent household bulbs in that the electrode contacts are closer together. As a result, the likelihood that shock may occur is somewhat reduced.
While incandescent lamps are generally driven off line voltage, fluorescent lamps typically require a ballast to start the lamp and regulate the power applied to the lamp. The voltage required to start the lamps depends on the lamp length and its diameter, with larger lamps requiring higher voltages. The ballast is designed to provide the proper starting and operating voltage required by the particular lamp. The ballast provides the proper voltage to fire the lamp and regulates the electric current flowing through the lamp to ensure stable light output. The ballast also supplies a correct voltage for the desired lamp operation and adjusts for voltage variations.
Traditionally, ballasts were of the electromagnetic, solid core type having a large transformer for providing the desired voltage and current. The voltage was typically provided to the lamp at or near the operating line voltage of 120 volts or 240 volts and frequency of 60 Hertz or 50 Hertz, respectively. Occasionally, the lamp is driven at a higher current in order to enhance the light output, but such overdriving of the lamp typically results in a shorter lamp lifetime.
Electronic or solid state ballasts provide greater energy efficiency by converting the power to light more efficiently than electromagnetic ballasts. Therefore, it is possible that an electronic ballast can provide a greater light output than an electromagnetic ballast with the same power consumption. The higher efficiency and light output is achieved by operating at a higher frequency than line frequency, and sometimes by operating at a higher voltage. As a result, it is possible that a ballast could acquire a relatively high open circuit voltage, as high as 750 volts, such as after ballast failure or some other electrical failure in the lighting system, which could consequently lead to injury or damage. For example, an improperly connected lamp in its respective sockets could lead to a high open circuit voltage, which in turn could cause arcing, over-heating, possible lamp failure and possible ballast failure.
Because of the higher driving voltages, the connection between the ballast and the lamp or bulb is important. Typically, fluorescent lamps have included bi-pin contacts or double recessed contacts at each end of the fluorescent tube. The pins are separated by a predetermined center-to-center pin separation distance, which may vary according to the size of the lamp. For larger diameter lamps, the spacing can be larger for recessed double contact lamps such as some T-10 and T-12 lamps, but otherwise will be the same for bi-pin T-8, T-10 and T-12 lamps. For example, a T-12 double recessed contact lamp will have a larger center-to-center contact spacing than a T-8 bi-pin lamp. The number
12
and the number 10 refer to the size, in eighths of an inch, of the lamp diameter.
Much of the hardware used with the T-12 and T-10 lamps have been relatively standardized. In one form of socket, commonly referred to as the tombstone socket, the pins of each end of the lamp are inserted sideways into the socket until the lamp is centered in each socket. After being centered, the lamp is rotated about its longitudinal axis, allowing the pins to come into contact after rotation with the contacts in each socket. This socket minimizes the possibility of one end of the lamp being inserted into one socket with subsequent energization of the lamp and the opposite free end being live. A shock could result from a live free lamp end.
In the tombstone style of socket, contact and illumination of the lamp is achieved by electrical contact between part of the outer surface of each pin and a portion of the surface of the contact. However, the electrical contact for each pin occurs only over a relatively small surface area, estimated to be in some circumstances about 0.015 square inches. As a result, any high current through the lamp results in a relatively,higher current density at the pins.
Another conventional socket for T-10 and T-12 lamps is a spring-biased recessed double contact socket, whereby one end of a lamp is inserted into the spring-biased socket, depressing the biased portion of the socket. Depressing the socket permits insertion of the opposite end of the lamp into the stationary socket on the fixture. However, nothing prevents the free end of the lamp from having a voltage and a potential for electric shock. While this socket configuration may account for expansion and contraction due to thermal cycling and extreme environmental conditions, the potential for electric shock remains.
Bulb size also affects the safety and efficacy of lighting systems. The longer the fluorescent lamp, for example, the greater the current required to
Anthony Inc.
Gushi Ross
Jeffer Mangels Butler & Marmaro LLP
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