Lighting unit and liquid crystal display device using the same

Details Lighting unit and liquid crystal display device using the same Lighting unit and liquid crystal display device using the same

1999-08-19

2001-05-15

O'Shea, Sandra (Department: 2875)

Illumination

Revolving

C362S035000, C362S260000, C362S023000, C362S026000, C362S318000, C362S390000, C362S369000, C362S216000, C349S070000, C349S025000

Reexamination Certificate

active

06231202

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a lighting unit employed in a translucent type liquid crystal display (LCD) device and an LCD device using the same lighting unit.
BACKGROUND OF THE INVENTION
In recent years, LCD devices have been widely used as a display unit of information apparatuses such as a notebook type personal computer (PC), a word processor and the like, and video apparatuses such as a portable television, a camcorder, a car-navigation system and the like. Those apparatuses require a display unit to be lightweight, have a slim body and have a low power consumption, and the LCD device meets these requirements. Many of the LCD devices are equipped with a lighting unit therein to realize a bright screen, where the lighting unit radiates behind the display.
There are two types of lighting units depending on a position of the light source, i.e. an edge-light type and a back-light type. In the edge-light type lighting unit, a light-conductive-panel is placed behind the LCD, and a line-light-source such as a fluorescent lamp is disposed at edges of the light conductive-panel. In the back-light type lighting unit, light sources are disposed just behind the LCD. The back-light type produces rather higher brightness but is not good for a slim housing, on the other hand, the edge-light type is good for a slim housing and has more uniform brightness on a light emitting-face but cannot produce high brightness.
The edge-light type lighting unit of LCD device has been preferred for a notebook type PC because of its thinner body. The edge-light type lighting unit has been also preferred for a camcorder and a car-navigation system, where the edge-type lighting units are equipped with a plurality of fluorescent lamps, an L-shaped lamp, or U-shaped lamp, in order to keep both the advantages, i.e. thinner body and high brightness.
FIG.
6
and
FIG. 7
illustrate a conventional edge-light type lighting unit employing an L-shaped fluorescent lamp.
In
FIGS. 6 and 7
, this lighting unit comprises the following elements:
(a) a transparent light conductive panel
51
for transmitting light;
(b) an L-shaped fluorescent lamp
52
disposed adjacent to two sides out of four sides of a panel
51
;
(c) reflecting film
54
for leading the light illuminated by the lamp
52
to an incident face
53
of the panel
51
;
(d) a reflector sheet
55
disposed behind the panel
51
and reflecting the light going outside from a rear face of the panel
51
to inside the panel
51
, thereby increasing illuminating light to be emitted from an outgoing face; and
(e) a diffusion panel
56
disposed on the front face (outgoing face) for increasing the uniformity of outgoing light.
In addition to those elements discussed above, there are still other elements such as: lead wires
58
connected to both electrodes
57
of lamp
52
for supplying a voltage from outside; a power supply such as an inverter (not shown) generating high frequency alternating current, and the power supply being wired to respective lead wires
58
via other lead wires
59
connected to the lead wires
58
by soldering; rubber holders
60
made of an insulating material such as rubber and formed in a cylindrical tube, holders
60
provided to cover exposed sections of respective lead wires
58
and
59
to secure safety because driving the lamp
52
generally requires a high voltage.
The light conductive panel
51
, the lamp
52
and other elements are held by a housing
61
so that the lighting unit is formed. The lamp
52
is disposed at a space
62
between the panel
51
and a side wall
70
of the housing
61
. At the same space
62
, the lead wires
59
are disposed for supplying a voltage to the lamp
52
.
A rear face cover
64
is disposed on the rear side of the housing
61
so that the panel
51
and the lamp
52
and others are secured and protected from outside.
However, the lighting unit constructed as discussed above has the following problems.
When the L-shaped fluorescent lamp
52
and lead-wires
59
are placed at the space
62
between the light conductive panel
51
and the side wall
70
of the housing
61
, enough allowance is preferably provided at space
62
. Because of the deviation of a curved-corner section
63
of the lamp
52
(approx. ±1°) and dimensional deviations of other components must be taken into consideration, otherwise the lamp
52
or the lead-wires
59
cannot be placed at the space
62
. If the lamp
52
and lead-wires
59
are tightly placed at the space
62
without enough room in the width direction, these elements will touch the housing
61
or the light conductive panel
51
, i.e., the heaviest element in the lighting unit and close to a rigid body, when the lighting unit is subjected to vibration or shock from the outside. As a result, the lamp
52
is damaged, or lead-wires
59
are cut due to the shock. Further, the space
62
must have enough width secured in addition to an effective emission area
500
, whereby the dimensions of the entire lighting unit become larger.
SUMMARY OF THE INVENTION
The present invention addresses the problems discussed above and aims to provide a compact lighting unit with excellent shock resistance as well as vibration resistance, and an LCD device using the same lighting unit.
The lighting unit of the present invention comprises the following elements:
(a) a fluorescent lamp having an L-shaped corner or U-shaped corners and disposed close to end faces of an incident face of alight-conductive-panel; and
(b) a housing for holding the light-conductive-panel and the lamp. The lamp is placed at a space between the panel and a side wall of the housing.
In the construction discussed above, the width of the space has different values at the places where both electrodes on lamp ends are disposed and at another place where a curved-corner section is disposed. This construction allows the entire lighting unit to be compact, and at the same time, it also allows the lamp to be disposed at the space even if a corner angle has a deviation and other components have dimensional deviations. As a result, a lighting unit with excellent shock resistance, as well as vibration resistance can be realized.
The LCD device of the present invention includes the lighting unit discussed above and a translucent LCD disposed on the outgoing side of the light conductive panel, so that a compact and highly reliable LCD device can be achieved.


REFERENCES:
patent: 4842378 (1989-06-01), Flasck et al.
patent: 4950053 (1990-08-01), Haim et al.
patent: 5990989 (1999-11-01), Ozawa
patent: 6050704 (2000-04-01), Park
patent: 6108060 (2000-08-01), Funamoto et al.
patent: 6111622 (2000-08-01), Abileah
patent: 94/01795 (1994-01-01), None

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