Compact fluorescent sign light unit

A compact fluorescent sign light unit includes a ballast, a flat backplate and a socket for receiving a fluorescent tube, such as a twin tube lamp. The ballast has a substantially flat backwall, attachment devices for rigidly attaching the ballast to a support, and electrical connectors for connecting to an electric current source. The backplate has a forward surface rigidly attached to the backwall of the ballast. The socket is attached to the forward surface such that the fluorescent light tube extends substantially perpendicularly away from the forward surface, above a part of the ballast which is not covered with the socket.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to fluorescent lighting devices and, more 
particularly, to fluorescent lighting units used in illuminated signs, 
logos or channel letters. 
2. Description of the Related Art 
Many lighting units are known in the art for replacing expensive neon light 
sources with fluorescent light sources. One of the advantages of 
fluorescent light sources is the fact that they provide a much higher 
light output and lighting intensity than comparable neon sources. Due to 
the higher intensity, however, the fluorescent tubes must be placed 
farther from the illuminated face since, otherwise, the tube becomes 
visible. This creates a light pattern on the face while it is desirable to 
have the face evenly lighted. In the art, this effect is known as a 
shadow. 
Another problem associated with prior art tube lights is found in the 
problematic adaptation to a given sign shape. Forming of neon or 
fluorescent tubes is a relatively time consuming effort and, additionally, 
it is rather expensive. In the case of breakage, they are not easily 
replaced. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide a compact 
fluorescent sign light unit, which overcomes the hereinafore-mentioned 
disadvantages of the heretofore-known devices of this general type and 
which allows easy installation, superior light output without shadow 
casting and easy replaceability in the case of failure. 
With the foregoing and other objects in view there is provided, in 
accordance with the invention, a compact fluorescent sign light unit, 
comprising: 
a ballast having a substantially flat backwall, attachment means for 
rigidly attaching the ballast to a support, and means for connecting to an 
electric current source; 
a substantially flat backplate having a forward surface rigidly attached to 
the backwall of the ballast; and 
socket means for receiving a fluorescent light tube, the socket means being 
attached to the forward surface such that the fluorescent light tube 
extends substantially perpendicularly away from the forward surface. 
In accordance with an added feature of the invention, the socket means is a 
socket for receiving a fluorescent twin tube lamp. The standard socket is 
preferably formed of plastic such as polycarbonet. The twin tube is a 
standard fluorescent twin tube of either 5W, 7W, 9W or 13W power. 
In accordance with an additional feature of the invention, the compact 
fluorescent sign light unit includes rivets rigidly connecting the socket 
means and/or the ballast to the backplate. While rivets are the preferred 
attachment means, it is also possible to clamp, screw, glue or otherwise 
connect the socket and the ballast to the backplate. 
In accordance with a concomitant feature of the invention, the ballast has 
a length, a width and a height, the backwall defining the width and the 
height; wherein the socket has a height substantially corresponding to a 
thickness of the fluorescent light tube, and the backplate has a width 
substantially equal to the width of the ballast and a height substantially 
corresponding to a sum of the height of the ballast and the height of the 
socket. The ballast has a substantially rectangular footprint and the 
backplate attaches to a narrow side face of the ballast. This assures the 
most compact configuration, with the twin tube extending flatly above the 
ballast and the socket covering only a smaller part of the footprint of 
the ballast. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in a 
compact fluorescent sign light unit, it is nevertheless not intended to be 
limited to the details shown, since various modifications and structural 
changes may be made therein without departing from the spirit of the 
invention and within the scope and range of equivalents of the claims. 
The construction of the invention, however, together with additional 
objects and advantages thereof will be best understood from the following 
description of the specific embodiment when read in connection with the 
accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the figures of the drawing in detail and first, 
particularly, to FIG. 1 thereof, there is seen a ballast 1, a backplate 2, 
a socket 3 and a fluorescent tube 4. The unit consists essentially of the 
members 1-3, whereby the backplate 2 is permanently and rigidly attached 
to the ballast 1 and the socket 3 is permanently and rigidly attached to 
the backplate 2. 
The backplate 2 has a forward surface at which the ballast 1 and the socket 
3 are attached. The height of the backplate 2 is slightly greater than a 
combined height of the ballast 1 and the socket 3. Both the ballast 1 and 
the socket 3 extend perpendicularly away from the forward surface of the 
backplate 2, such that a minimum footprint expanse is attained. The 
minimum footprint is necessary in the context of this invention so as not 
to cause shadow casting and to allow densest possible packing of the units 
relative to one another. 
The ballast 1, the socket 3, and the fluorescent tube 4 are commercially 
available. By way of example, the socket 3 may be purchased from Edwin 
Gaynor Co. of Stradford, Connecticut, or from Triboro Socket Co. of Doyle, 
Pennsylvania; the ballast 1, which must be a type I, outdoor ballast, may 
be purchased from the Robertson Transformer Co. of Blue Island, Illinois, 
or from Keystone Transformer Co. of Pennsylvania; the fluorescent bulb 4 
is available from Osram Sylvania or from Philips Lighting Co. 
The fluorescent bulb 4 is preferably a standard white twin tube lamp which 
comes in different standard sizes, for instance in 5W, 7W, 9W and 13W. 
In the preferred embodiment, the backplate 2 is rivetted to the ballast 1 
and to the socket 3. The backplate 2 is preferably formed of aluminum. 
Rivets 5 are preferably #44 metal rivets. The ballast 1 has a steel casing 
with a number of attachment extensions 6 with which the sign light unit is 
attached to a support 7 of a sign light. The socket 3 is formed of 
polycarbonet material. 
The unit comes in different sizes, in accordance with the rated lighting 
power. The 13 watt unit is 7.5" long, 2.25" tall and 2.0" wide. The lower 
wattage units are about 2.25" wide and 2" tall. Depending on the length of 
the fluorescent bulb, the lengths of the units are 4.5" (5W), 5.5" (7W) 
and 6.75" (9W), respectively. Electric current consumption averages about 
0.028 amperes at 120 V at 60 Hz. Cables 7 are provided for wiring the 
ballast to an electric current source. 
One of the advantages of the fluorescent sign light units is their 
dependability in terms of temperature and starting times. It has been 
found that starting temperatures for the 13W, 7W and 5W units may be as 
low as 0.degree. F. The minimum starting temperature for the 9W unit has 
been found to be about 20.degree. F. 
Due to the compactness of the unit, many distribution schemes within the 
light channel or light cavity are possible. For best results, between 
three and four units are provided per upright foot of block, spurred or 
script channel letters with thick and thin strokes from 3" to 10". For box 
signs, it has been found that one unit per square foot of sign single or 
double face provides the best results. 
In the case of plastic or LEXAN (TM) face signs, the fluorescent bulb 
should be placed about 3" from the face. Accordingly, the minimum depth of 
the sign is only 5.5". It is further noted that, in light of the 
application of the compact unit to signs, all of the parts must be of a 
light color (preferably white).