Liquid crystal cells – elements and systems – Particular structure – Particular illumination
Reexamination Certificate
1999-12-16
2001-02-20
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Particular illumination
C349S062000, C349S064000, C349S137000
Reexamination Certificate
active
06191833
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to high-brightness liquid crystal display devices that are high in optical use efficiency and excellent in viewing-angle characteristics.
2. Description of the Related Art
Liquid crystal display devices are widely used as those devices for use in visually displaying a variety of kinds of images including still images and video images.
Such liquid crystal display devices of this type are basically arranged so that two (a pair of) substrates at least one of which is made of transparent glass or else are spatially stacked over each other with a liquid crystal layer sandwiched between them to thereby constitute a so-called liquid crystal panel, which devices are classified into two forms, one of which is for performing turn-on/off operations of a specified picture element or “pixel” by selective application of a voltage to various electrodes as formed on the substrate of the above-noted liquid crystal panel to constitute the pixel, and the other of which is for performing turn-on/off operations of certain pixel by forming an active element for pixel selection along with the various electrodes and then selecting this active element.
Especially the liquid crystal display devices of the latter type are called active-matrix devices, which offer several technical advantages including increased contrast performance and high-speed displayabilities or the like and, for the very reason, are inevitable as “de facto standard” display modules among presently available liquid crystal display devices.
Prior known active-matrix liquid crystal display devices include those of what is called the “vertical electric field” scheme for applying between an electrode formed on one substrate and an electrode formed on the other substrate an electric field for use in changing the optical orientation or alignment direction of the liquid crystal layer, and others of the so-called “lateral electric field” scheme (also known as in-plane switching type or “IPS” scheme) for letting the direction of an electric field being applied to the liquid crystal layer extend in substantially parallel to substrate surfaces.
The various types of liquid crystal display devices are each designed to include a light source device (generally called a “back-light” unit) for illumination of the liquid crystal panel from the back side thereof. Currently available back-light unit typically include those of the side-edge scheme with more than one lamp (linear light source such as a fluorescent tube or light-emitting diode) disposed on the lateral side of a light guide plate used, and others of the direct downward scheme with a lamp disposed immediately beneath the liquid crystal panel.
Especially for notebook personal computers requiring reduced thickness and light weight, it is a general approach to employ back-light units of the side edge scheme.
FIG. 14
is a diagram depicting an exploded perspective view of one exemplary structure of a liquid crystal display device. In
FIG. 14
, “SHD” designates a shield casing (also known as metal frame) made of a metal plate; WD denotes a display window; INS
1
-
3
indicate dielectric sheets; PCB
1
-
3
represent printed circuit boards (PCB
1
is a drain-side circuit board for use as an image signal driver circuit board, PCB
2
is a gate-side circuit board, and PCB
3
is an interface circuit board); JN
1
-
3
are joiners for electrical connection between associated ones of the circuit boards PCB
1
-
3
; TCP
1
, TCP
2
are tape carrier packages; PNL, a liquid crystal panel; GC, rubber cushion; ILS, optical shielding spacer; PRS, prism sheet; SPS, optical diffuser sheet; GLB, light guide plate; RFS, reflection sheet; MCA, lower-side casing (mold frame) as formed by all-at-a-time machining; MO, opening of lower-side casing MCA; ;LP, fluorescent tube; LPC, lamp cable; GB, rubber bush for support of the fluorescent tube LP; BAT, both-side adhesive tape; BL, back-light unit consisting essentially of a linear light source (fluorescent tube) LP and light guide plate GLB and the like, wherein diffuser plate members are stacked or laminated over one another to assemble the liquid crystal display module MDL.
Although in the illustrative liquid crystal display device the reflective sheet RFS is disposed on the lower surface (back plane) of the back-light BL with the diffuser sheet SPS and prism sheet PRS being laminated on the upper surface thereof, another diffuser sheet SPS may be further stacked on the prism sheet PRS where appropriate. In addition, while in this arrangement a single unit of linear light source LP is laid out along one side of the light guide plate GLB with wedge-like cross-section, there are also known a large-screen size device which is designed to employ two or more light sources together or alternatively the one that makes use of a flat plate-shaped light guide plate having its two parallel opposite sides along each of which one or a plurality of linear light sources are installed. Additionally the remaining components are explained by adding to the drawing their parts names along with the reference characters thereof
The liquid crystal display module MDL is structured from two types of accommodation/support members such as the lower side casing MCA and shield casing SHD and is arranged by integrally engaging the shield case SHD and the lower side case MCA together, wherein the former is made of metal to receive therein the dielectric sheets INS
1
-
3
and circuit boards PCB
1
-
3
plus liquid crystal panel PNL whereas the latter receives therein the back-light BL that consists essentially of the fluorescent tube LP and light guide plate GLB plus prism sheet PRS and others.
The image signal line driving circuit board PCB
1
has a built-in integrated circuit (IC) chip for use in driving each pixel of the liquid crystal panel PNL; the interface circuit board PCB
3
has components mounted thereon, including an IC chip for receiving an image signal(s) from an external host and also a control signal or signals such as a timing signal or the like along with a timing converter TCON for processing the timing to generate a clock signal.
The clock signal as generated by the timing converter is supplied to the IC chip mounted on the image signal line drive circuit board PCB
1
via a clock signal line CLL railed on the interface circuit board PCB
3
and image signal line driving circuit board PCB
1
.
The interface circuit board PCB
3
and image signal line driving circuit board PCB
1
are multilayer lead pattern substrates, wherein the clock signal line CLL is formed as an internal lead of the interface circuit board PCB
3
and image signal line driving circuit board PCB
1
.
Note that the liquid crystal panel PNL is arranged so that the drainside circuit board PCB
1
for driving TFTs and gate-side circuit board PCB
2
plus interface circuit board PCB
3
are connected by the tape carrier packages TCP
1
, TCP
2
while associative ones of such circuit boards are connected together by the joiners JN
1
,
2
,
3
.
FIG. 15
is a diagram pictorially representing a sectional view of a multilayer structure of the liquid crystal display device shown in
FIG. 14
, wherein the liquid crystal layer LC is sandwiched between the lower substrate SUBI and upper substrate SUB
2
to constitute the liquid crystal panel, the lower substrate SUB
1
and upper substrate SUB
2
having their outer surfaces on which a double-layer structure consisting of a lower phase difference plate PHD
1
and lower polarization plate POL
1
and a bilayer structure of an upper phase difference plate PHD
2
and upper polarization plate POL
2
are stacked respectively.
This liquid crystal panel has its back surface (rear plane) on which the back-light BL is placed while letting an optical sheet consisting of a lamination of the diffuser sheet SPS and prism sheet PRS be inserted between the liquid crystal panel and the back-light BL.
The back-light BL used is of the side-edge scheme type, wherein the linear light source (fluorescent tube or light-emittin
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Parker Kenneth
Qi Mike
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