Illumination – Elongated source light unit or support – With means to accommodate additional circuit element
Reexamination Certificate
2001-10-31
2003-05-27
O'Shea, Sandra (Department: 2875)
Illumination
Elongated source light unit or support
With means to accommodate additional circuit element
C362S296040, C362S341000, C362S217060, C349S070000
Reexamination Certificate
active
06568831
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for attaching a cable for supplying power to a fluorescent tube, a method for manufacturing a surface illuminating device with the fluorescent tube, a fluorescent tube with cables, a surface illuminating device with the fluorescent tube and a liquid crystal display device having the surface illuminating device.
The present application claims priority of Japanese Patent Application No. 2000-333819 filed on Oct. 31, 2000.
2. Description of the Related Art
In recent years, in portable information devices such as notebook-type personal computers, it is required that they are made lightweight and thin. At the same time, as shown in
FIG. 34
, for example, in a notebook-type personal computer
101
, an effort has been made to make a display area relatively large in size by making narrow, as much as possible, a width of a plaque edge portion
103
used to hold an edge portion of a liquid crystal display device
102
and being not contributing directly to a liquid crystal display.
Moreover, as shown in
FIGS. 35 and 36
, the liquid crystal display device
102
includes, for example, a transmissive-type TFT (Thin Film Transistor) liquid crystal panel
104
, a backlight
105
used to apply illuminating light from its rear side and a front case
106
used as a holding frame to hold a main body of the liquid crystal display device
102
. Here, the plaque edge portion
103
has to have a thickness of, for example, about 7 mm.
Moreover, the backlight
105
, as shown in
FIGS. 36 and 37
, includes a fluorescent tube
108
, a reflector
109
used to reflect light emitted from the fluorescent tube
108
, a rear chassis
110
used as a holding frame on a rear side of the backlight
105
, a light guiding plate
111
used to take in direct light from the fluorescent tube
108
or light reflected off the reflector
109
and to emit it as planar light, a reflecting sheet
112
disposed on the rear chassis
110
and used to reflect light emitted from the fluorescent tube
108
to a side of the light guiding plate
111
, optical correction sheets
113
,
113
, . . . , made up of a plurality of pieces of prism sheets, diffusion sheets, or a like used to highly accurately correct variations in luminance and to improve uniformity in luminance, and a lamp cover
114
.
The fluorescent tube
108
, for example, in the case of the fluorescent tube to be used for a 14-inch type liquid crystal display device, is so formed that it has a shape of a narrow tube with a diameter of about 2 mm and a length of about 190 mm and that its both ends are sealed so that its inside portion is filled with mercury gas and inert gas in a sealed manner and that a pair of electrodes is sealed at both ends of the long cylindrical-shaped glass tube and that an ultraviolet ray reflecting layer and a phosphor layer are formed in an inside face of the glass tube. To each of the electrodes is connected each of lead conductors
115
a
and
115
b
. A pair of cables
116
a
and
116
b
for supplying power is connected to the fluorescent tube
108
. Each of holding rubber caps
117
a
and
117
b
used to hold the fluorescent tube
108
is connected to each of ends of the fluorescent tube
108
. The cables
116
a
and
116
b
are drawn out from a cable drawing-port
110
a
formed in the rear chassis
110
.
On a side being opposite to the cable drawing-port
110
a
, as shown in
FIGS. 38 and 39
, the cable
116
a
is connected in a direction being approximately perpendicular to the fluorescent tube
108
. That is, as shown in
FIG. 39
, the lead conductor
115
a
connected to the fluorescent tube
108
is bent at right angles. After having soldered the lead conductor
115
a
to a core wire
118
a
of the cable
116
a
, an end on a side of the cable
116
a
is covered with a thermal shrinkage tube
119
and fixed. Then, the L-shaped holding rubber cap
117
a
is attached to ends of the cable
116
a
and the fluorescent tube
108
and fixed. To protect connected portions, the holding rubber cap
117
a
is covered with another thermal shrinkage tube
120
. As a material for the holding rubber cap
117
a
, a comparatively flexible material that can be easily attached is selected.
The methods to protect such the connected portions as described above by using the holding rubber cap is disclosed in, for example, Japanese Patent Application Laid-open Nos. Hei 7-281160 and Hei 7-281161.
In the disclosed method, as shown in FIG.
37
and
FIG. 40
, when the fluorescent tube
108
is embedded in the backlight
105
, in order to prevent the connected portion in which the fluorescent tube
108
is connected to the cable
116
a
being subjected to stresses, the cable
116
a
is hung on a bump projection piece
110
b
formed on the rear chassis
110
and is then routed around to form a margin portion
121
and is finally drawn out from the cable drawing-port
110
a.
When the fluorescent tube
108
is embedded in the backlight
105
, on a side being opposite to the cable drawing-port
110
a
of the cable
116
a
, for example, as shown in
FIG. 41
, a core wire
118
b
of the cable
116
b
is soldered, with a margin portion
122
formed by a tip portion of the core wire
118
b
being bent in a shape of a letter “U”, to the lead conductor
115
b
of the fluorescent tube
108
to be connected to each other and then a holding rubber cap
117
b
is covered to protect the connected portion.
However, the above conventional method has problems. That is, in the case of the method, in particular, in which the cable
116
a
is attached to an axis of the fluorescent tube
108
at right angles, to obtain mechanical strength at the connected portion, as described above, the cable
116
a
is hung on the bump projection piece
110
b
formed on the rear chassis
110
and is then routed around to form the margin portion
121
and is finally drawn out from the cable drawing-port
110
a
. As a result, a width of the corresponding plaque edge portion
103
becomes large. This causes a lowered ratio of a front area of the backlight
105
, serving as a region in which light is emitted when the fluorescent tube
108
is embedded in the backlight
105
, to its all surface area and a lowered ratio of a front area of the liquid crystal display device
102
, serving as a liquid crystal displaying region when the backlight
105
is embedded in the liquid crystal display device
102
, to its all surface area. For example, if a diameter of the cable
116
b
is about 1.6 mm and a thickness of the bump projection piece
110
b
is about 1 mm, to route the cable
116
a
, redundant space of at least about 3 mm along an axial direction of the fluorescent tube
108
has to be expended.
Moreover, when the cable
116
a
is attached to the axis of the fluorescent tube
108
at right angles, the lead conductor
115
a
is also bent at right angles. The holding rubber cap
117
a
is made up of flexible and soft materials. These factors cause the mechanical strength in the connected portions to become lower. If, therefore, a stress is applied on the connected portions in which the fluorescent tube
108
is connected to the cable
116
a
, a failure such as breaking of wires or a like readily occurs. Since the thermal shrinkage tubes
119
and
120
are used at the connected portion in which the fluorescent tube
108
is connected to the cable
116
a
, component counts become high and many man-hours and much time are required in assembling process of the connected portion.
Furthermore, there is another problem. That is, when the holding rubber cap
117
a
is used to position the reflector
109
to the fluorescent tube
108
, the holding rubber cap
117
a
is easily deformed, which makes it difficult to perform exact positioning of the reflector
109
to the fluorescent tube
108
. Because of this, for example, the reflector
109
is attached to a place being deviated from its originally expected position. This causes direct light from the fluorescent tube
108
or light reflected off the reflector
109
to
Fukuyoshi Hirokazu
Ono Shin-Ichirou
DelGizzi Ronald E.
Katten Muchin Zavis & Rosenman
NEC LCD Technologies Ltd.
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