Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific voltage responsive fault sensor
Reexamination Certificate
2002-02-27
2003-09-09
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific voltage responsive fault sensor
C361S018000, C361S038000
Reexamination Certificate
active
06618231
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to neon sign transformers and power supplies and more specifically to neon sign transformer and power supply modules and mating receptacles for use in neon signs.
In the neon sign industry, the luminescent tubes of a neon sign are typically permanently attached to a back plane or other support structure. This is typically the case because the neon tubes have a very long life span compared to other light sources such as incandescent or fluorescent light bulbs. Due to this long life, neon tubes typically do not require much servicing and can therefore be substantially fixed in place on the neon sign.
Although the luminescent tubes of a neon sign are referred to herein as being neon tubes, it should be understood that neon signs utilize a variety of types of luminescent tubes filled with a variety of gases including, but not limited to, neon gas. All of these various combinations of tube types and gas types are well known to those skilled in the neon sign art and are commonly referred to as neon even though they may not include any neon gas. Therefore, it should be understood that the general term “neon sign”, as used hereinafter, refers to all of these various combinations of types of luminescent tubes and types of gases that are used in what is commonly referred to as neon signs. Also, the term “neon sign”, as used hereinafter, refers to any neon installation including, but not limited to, window signs, point of purchase signs, displays, architectural borders, soffit lighting, channel letters, accents, outdoor neon signs, or any other application that utilizes a neon tube. The term “neon tube”, as used hereinafter, refers to any processed and sealed luminescent tube that utilizes any combination of the above mentioned types of gases.
Neon signs require high voltage transformers or power supplies to drive the neon tubes of the neon sign. Traditionally, these high voltage transformers are provided in the form of “core and coil” type transformers. These core and coil transformers have proved to be relatively reliable and relatively long lived. Because of this, the high voltage transformers required by the neon sign have typically been fairly permanently attached to the neon sign and hardwired to the neon tube. In the past, this has not been much of a problem to the neon sign industry because the transformers and the neon tubes did not need to be serviced very often. Also, in the case of conventional large outdoor neon signs, it has been perfectly acceptable that a qualified technician capable of rewiring a neon tube or transformer was required in order to service the neon sign.
However, in the specific area of small window neon signs and point of purchase neon signs, permanently attaching a core and coil transformer to the small neon sign presents special problems. In the window and point of purchase neon sign industry, it is becoming more important to be able to ship individual small neon signs directly to a customer. This is very difficult to do with a small neon sign using a core and coil transformer hardwired to the sign. This is because the weight of the core and coil transformer causes an unacceptable amount of breakage of the neon tubes during shipping. Therefore, there is a need for an easily detachable neon sign transformer that can be shipped separately from the sign and then attached to the sign by the customer without requiring the involvement of a qualified technician or electrician.
As mentioned above, neon signs require high voltage transformers to power the neon tubes. This poses safety concerns in situations in which an inexperienced user is expected to connect a high voltage transformer to a neon sign. Due to these safety concerns, prior art detachable neon transformers have been designed to be installed and serviced only by qualified personnel such as an electrician.
On example of such a transformer is a channel letter transformer designated by reference numeral
100
and illustrated in FIG.
1
. In this case, transformer
100
is transformer model PBKM-751 series provided by France. This transformer is designed to slide onto the electrodes at the ends of a neon channel letter
102
of a large outdoor neon backlit sign. As illustrated in
FIG. 1
, transformer
100
includes a pair of secondary contacts
104
that provide high voltage power to neon channel letter
102
. Transformer
100
also includes primary input wires
106
for providing power, at a conventional input voltage, to the transformer. Wires
106
are typically hardwired to a power source by a qualified installer or electrician when the channel letter is installed.
Transformer
100
transforms the conventional input voltage from wires
106
into the required high voltage, referred to herein as the secondary voltage. This secondary voltage is typically in the range of 1000 volts to 15000 volts for a neon sign depending on the length and type of the neon tube being powered. With this configuration, secondary contacts
104
are energized at the high voltage output of the transformer any time that wires
106
are electrically connected to an active power source. This presents a significant safety risk and is one of the major reasons this configuration is designed to be only installed and serviced by a qualified installer. For this reason, this configuration would be unacceptable for use in a small window neon sign or a point of purchase neon sign in which the customer was expected to connect the transformer to the neon sign. Also, because this configuration requires the transformer to be hardwired to a power source, this configuration requires a qualified installer to install the transformer.
In order to overcome some of the safety concerns with high voltage transformers, new requirements for ground fault interrupt (GFI) circuitry and open circuit detection circuitry have been becoming more common. In cases where this circuitry is required, the cost of providing a particular core and coil transformer may go up substantially. In the case of a small core and coil transformer for a small window neon sign or a small point of purchase neon sign, this detection circuitry may double the cost of providing the traditional core and coil type transformer. This increased cost is very significant for the window sign and point of purchase sign industry segment due to extreme price sensitivity in this industry segment and due to the fact that the transformer is the most expensive component of this type of neon sign.
Solid state power supplies or transformers are a relatively new alternative to traditional core and coil transformers in the neon sign industry. Because solid state power supplies are already constructed from electronic components typically mounted on a printed circuit board, it is relatively easy and cost effective to add GFI and open circuit detection circuitry to this type of transformer. Because of this substantial cost advantage, there is a strong trend toward the use of solid state power supplies in the window sign and point of purchase sign industry.
Unfortunately, the solid state power supplies currently available do not appear to be nearly as reliable as conventional core and coil transformers. This seems to be caused by the combination of several factors. First, a large number of electronic components are typically used to provide a solid state power supply. A failure of any one of these components can cause the power supply to fail. Second, the pressure to use low cost components in order to provide a low cost solid state power supply increases the chances that one of the components will fail. And finally, the inclusion of GFI and open circuit detection circuitry that may shut off the power supply, as the circuits are designed to do, may contribute to the general perception that a neon sign using a solid state power supply has failed.
In recent years, the increased failure rates of the solid state power supplies have been significantly impacting the reputation of neon signs. Previously, neon signs were thought to be very durabl
Beyer Jay R
Jackson Stephen W.
Zeon Corporation
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