Light diffuser device

Details Light diffuser device Light diffuser device

1998-03-31

2001-03-13

O'Shea, Sandra (Department: 2875)

Illumination

Modifier mountable on light source envelope

C362S026000, C362S256000, C362S355000, C428S038000, C428S046000

Reexamination Certificate

active

06200004

ABSTRACT:

FIELD OF THE INVENTION
The present invention is directed to a device for enhancing the diffusion of the light emitted from a light source. Typical light sources include fluorescent tubes, also known as fluorescent bulbs or fluorescent lamps. These fluorescent tubes may be employed in cabinets or light boxes of signs, such that when the devices of the present invention are used in conjunction with the fluorescent tubes in these signs, the depth of the cabinets, and ultimately the depth of the signs can be reduced, when compared to conventional signs.
BACKGROUND OF THE INVENTION
Signage is common for basic communications and is the most popular form of advertising worldwide. Advertising signage, for example, is extremely effective in the form of illuminated point of purchase signs, commonly found in airport terminals, bus and train stations, sporting arenas or stadiums, convention centers, hotels, and other public walkways, or places of high pedestrian traffic. These signs are decorative multi color arrays and are retained in outwardly protruding illuminated cabinets or light boxes, the cabinets mounted on a wall, or other stable support structure, for example, a balcony front at a sporting arena or stadium.
An exemplary sign
20
of overall length (L) and overall depth (D) is mounted on a wall
21
, as illustrated in
FIGS. 1
,
2
a
, and
2
b
. These drawing figures are diagrammatic, to illustrate the structures detailed below and accordingly are not to scale. This sign
20
includes a cabinet
22
(also known as a light box), of sheet metal or the like, with a body
24
, having rear
25
, side
26
a
,
26
b
, upper
27
and lower
28
walls and an open front (side). The body
24
may also include borders
29
(continuous or non-continuous along the periphery of the open side of the cabinet body
24
), affixed to the cabinet walls
26
a
,
26
b
,
27
,
28
by conventional mechanisms, to assist in preventing the graphic unit
32
from moving (or being pushed) into the cabinet
22
. The borders
29
preferably have their outermost surfaces flush with the edges of the side
26
a
,
26
b
, upper
27
and lower
28
walls at the open side of the cabinet body
24
, and may include an indented section (not shown), typically referred to as a screw trough, for receiving screws
35
, rivets or the like.
The cabinet
22
encloses lights, for example, 800 milliamp (ma) fluorescent tubes
30
(also referred to as fluorescent bulbs or fluorescent lamps), of lengths ranging from eighteen inches to ten feet (46 cm to 305 cm), and diameters typically approximately 1.5 inches (3.81 cm), or other suitable illuminating devices. In this sign
20
, the fluorescent tube arrangement(s) are exemplary, and additional similar arrangements within the cabinet
22
are permissible if desired.
A graphic unit
32
is positioned in a retainer
34
(frame). This retainer
34
holds the graphic unit
32
in place against the cabinet body
24
, as the graphic unit
32
abuts the edges of the side
26
a
,
26
b
, upper
27
and lower
28
walls and the borders
29
. The retainer
34
is made of individual members
34
a
, preferably four (one for each cabinet periphery side), each member having lips
34
b
that abut the edges of the side
26
a
,
26
b
, upper
27
and lower
28
walls when the sign
20
is properly formed. Each of the members
34
a
that form the retainer
34
attach to the cabinet body
24
by clamping screws
35
, conventional threaded screws received in openings in the cabinet body
24
, latches, hinges, or other similar attachments. When any retainer member
34
a
is removed from the cabinet body
24
, the graphic unit
32
can be removed by being slid therefrom. Other conventional retainers for the graphic unit
32
, such as friction fitting members, are also permissible.
The graphic unit
32
, typically includes a graphic
36
(typically a transparency), sandwiched between a diffuser panel
38
(typically a translucent polymeric or plastic sheet), oriented rearward toward the cabinet rear wall
25
and a protective cover member
40
(typically a transparent or clear polymeric material), held in contact by the sandwich arrangement. The cabinet
22
has an internal length (1), from the innermost surface of the sidewall
26
a
to the innermost surface of the opposite sidewall
26
b
, and an internal depth (d), from the rear wall
25
to diffuser panel
38
(alternately expressed as the distance from the rear wall
25
to the plane formed by the edges of the side
26
a
,
26
b
, upper
27
and lower
28
walls along the open side of the cabinet body
24
).
In the sign
20
, the internal cabinet length (1) is 10 feet (3.04 m) or less, as it includes a single fluorescent tube
30
or tubes, depending on the sign height, that span or spans the entire internal cabinet length (1). This fluorescent tube
30
is received in electrical connection and coaxial alignment with the respective sockets
42
a
,
42
b
(the center point of the socket substantially aligned with the center point of the fluorescent tube). For example, these sockets
42
a
,
42
b
, may be KULKA brand lamp sockets Cat. No. 582, 660 W-600 V/1000 V, available from Voltarc Technologies, Inc., 400 Captain Neville Drive, Waterbury, Conn. 06705, USA. The sockets
42
a
,
42
b
are mounted on oppositely disposed sidewalls
26
a
,
26
b
of the cabinet
22
. These sidewalls
26
a
,
26
b
may be of variable thickness to define wireways or raceways, which accommodate electrical hardware (wiring) for the sockets
42
a
,
42
b
. At least one of the sockets, shown here as socket
42
a
mounted on sidewall
26
a
, is spring loaded (depressably mounted) by a spring mechanism, to allow for easy fluorescent tube
30
removal, by depressing the spring loaded socket
42
a.
The arrangement of the fluorescent tubes
30
in the cabinet
22
of the sign
20
, determines the internal cabinet depth (d), that serves to establish the overall sign depth (D). The internal cabinet depth (d) is less than the overall sign depths (D), as this overall depth (D) accounts for the thickness of the cabinet rear wall
25
, any retainer portions that do not overlap with the cabinet body
24
(the non-overlapping portions of the retainer
34
including the graphic unit
32
). This internal depth “d” is a combination of two distances, “d
1
”, the cabinet rear wall to socket center/fluorescent tube (light) center distance, and “d
2
”, the socket center/fluorescent tube center to diffuser panel
38
distance.
The distance (d
1
) between the rear wall
25
and the socket center/fluorescent tube center is determined by the distance needed to separate the fluorescent tube
30
from the cabinet rear wall
25
. This distance (d
1
) is based on socket dimensions and safety concerns. For example, this distance may be approximately 1.1875 inches (3.02 cm) or greater.
The distance between the socket center/fluorescent tube center and the diffuser panel (d
2
) is in accordance with industry standards. It is the distance between the socket center/light center and the diffuser panel
38
, where the light diffuses uniformly throughout the cabinet
22
, such that: 1) the viewer sees the graphic illuminated at a uniform intensity distribution, as opposed to areas of greater intensity, known as “hot spots” and lesser intensity, known as “shadows”; and 2) the viewer has difficulty in determining the direction of the fluorescent tubes (lights)
30
in the cabinet
22
. Typically, this distance is approximately 4 inches.
The combined distances, the sum of which is the respective internal cabinet depth, d, for the sign
20
is greater than four inches (due largely in part to the d
2
distance of approximately 4 inches), whereby the overall cabinet depth D, for the sign
20
, is also greater than four inches. The resultant sign
20
, when mounted on a wall
21
or the like, extends (protrudes) more than four inches therefrom, and is thus, commonly referred to and classified as “high profile.”
“High profile” signs, such as the sign
20
shown, exhibit substantial drawbacks. The “high profile” c

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