Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
2001-04-13
2003-04-08
Kim, Robert H. (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C349S110000, C349S111000, C349S151000, C349S152000
Reexamination Certificate
active
06545731
ABSTRACT:
FIELD OF TECHNOLOGY
This invention pertains to the field of liquid crystal display (LCD) devices, such as liquid crystal on silicon (LCOS) devices, and more particularly to light shielding in such devices.
BACKGROUND AND SUMMARY
Reflective LCD devices are well known. Examples of such devices, and in particular active matrix devices, are shown in U.S. Pat. Nos. 6,023,309 and 6,052,165. With reference to the following description, familiarity with conventional features of such devices will be assumed, so that only features bearing on the present invention will be described.
FIG. 1
shows a portion of typical prior-art reflective LCD device
100
. The reflective LCD device
100
may generally be divided into a pixel region
100
a
(active region) and a peripheral region
100
b
. The pixel region
100
a
includes an array of pixel elements and the peripheral region
100
b
includes driver circuits
105
for supplying driving signals to each of the pixel elements.
The LCD device
100
comprises, in relevant part, a silicon substrate
110
, an insulating layer
112
, a liquid crystal layer
114
, a transparent electrode
116
, such as indium-tin-oxide (ITO), and a glass layer
118
. A reflective mirror (pixel) metal layer
120
is provided beneath the liquid crystal layer
114
on the insulating layer
112
. The mirror metal layer
120
includes a plurality of individual reflective pixel electrodes
120
a
in the pixel region
100
a
, with light transmissive regions
122
being located between the pixel electrodes
120
a.
Also provided in the insulating layer
112
and between the mirror metal layer
120
and the substrate
110
are at least three metal layers
124
,
128
and
130
. In the pixel region
100
a
, the metal layers
128
and
130
form mutually-orthogonal row and column lines, which may be connected to gate and source electrodes of MOS transistors (not shown in
FIG. 1
) for pixel elements fabricated in the underlying substrate
110
. In the peripheral region
100
b
, the metal layers
128
and
130
form signal routing lines used for routing various signals of the driver circuits
105
. Also, metal plugs or vias
132
are provided for connecting various portions of first, second, third and fourth metal layers
120
,
124
,
128
,
130
with each other.
In addition, the metal layer
124
is provided to prevent light entering the device, such as through the transmissive regions
122
between the pixel electrodes
120
a
, from reaching the substrate
110
where it might induce leakage currents or otherwise interfere with proper device operation. Note that while portions of metal layers
128
or
130
may incidentally block a small portion of light entering the device, the structure of
FIG. 1
requires a separate metal layer
124
to be dedicated to provide the required degree of light blocking in the peripheral region
100
b
. This is due to the fact that light trapped between the two metal layers
120
and
124
can propagate over long distances due to multiple reflections between the layers.
While this prior-art solution is satisfactory for blocking light from reaching the substrate
110
in the peripheral region
100
b
, it requires the additional dedicated metal layer
124
in the peripheral region
100
b
. However, the area required for the driver circuits
105
could be reduced if the metal layer
124
could also be used for routing driver circuitry signals in the peripheral region
100
b
, instead of being dedicated only to light blocking.
Accordingly, it would be desirable to accomplish the light-blocking function of the dedicated metal layer in the peripheral region of the prior art devices without using a separate dedicated metal layer in this region. Other and further objects and advantages will appear hereinafter.
Therefore, in one aspect, the invention provides a liquid crystal display (LCD) which blocks light in the peripheral driver circuit region of the device without providing a dedicated metal layer in this region for this purpose.
Accordingly, an LCD device is provided having a pixel region and a peripheral region adjacent to the pixel region, comprising a substrate, a first metal layer above the substrate including an array of pixel electrodes in the pixel region and a peripheral portion in the peripheral region, a second metal layer beneath the array of pixel electrodes, and a wall disposed between the second and first metal layers along an edge of the pixel region and extending upward to the peripheral portion of the first metal layer.
REFERENCES:
patent: 5410344 (1995-04-01), Graves et al.
patent: 6005597 (1999-12-01), Barrett et al.
patent: 6081305 (2000-06-01), Sato et al.
patent: WO9837696 (1998-08-01), None
Smyth et al., “Surfing The Digital Wave Generating Personalised TV Listings Using Collaborative, Case-Basedrecommendation, ” Case-Based Reasoning Research And Development. International Conference, XX, XX, Jul. 1999, pp. 561-571.
Albu Lucian R.
Hausser Stefan
Janssen Peter J.
Kraft Karl-Heinz
Melnik George A.
Koninklijke Philips Electronics , N.V.
Nguyen Hoan
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