Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-04-10
2002-10-15
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S008000, C349S084000, C349S106000, C349S109000
Reexamination Certificate
active
06466285
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal device equipped with microlenses and a liquid crystal display apparatus, particularly a full-color liquid crystal display apparatus, including the liquid crystal device.
In today's multi-media world, there is an increasing demand for apparatuses and devices which communicate with picture data. Among these, a liquid crystal display apparatus has gained public attention because of its small thickness and small power consumption. A major industry comparable to the semiconductor industry has already developed in that regard. The liquid crystal display apparatus has been principally used in notebook-type personal computers having a picture area size of 10-20 inches, but it is believed to be adaptable to larger-area display apparatuses not only for personal computers, but also for workstations and home television sets.
An increase in picture size is accompanied by problems, such as the need for larger-scale and expensive production apparatuses and the requirement for extensive electrical requirements for driving such large-area apparatuses. These problems lead to a severe increase in production cost, which increases to the second to third power of the picture area increase.
Accordingly, in recent years, attention has been given to a projection-type liquid crystal display system, wherein a small-size liquid crystal display panel is prepared, and a picture displayed thereon is optically enlarged to be displayed to a viewer. This is advantageous because the production of a small-size liquid crystal panel can take advantage of advances in production technology which allow the simultaneous achievement of a smaller size, an improved performance and a cost reduction, similarly as a scaling rule regarding a higher density, a higher definition, a performance improvement and a cost reduction in production of semiconductor devices.
For the above purpose and especially in the case of a TFT-driven liquid crystal display panel, sufficiently small TFTs (thin film transistors) having a sufficient drive power are required; the current trend is a shift from amorphous Si TFTs to polycrystalline Si TFTs and further to TFTs formed on a single-crystalline Si substrate. Accordingly, there has been proposed a liquid crystal display apparatus including an integral structure of a display region and a peripheral drive circuit, wherein not only TFTs but also a peripheral drive circuit such as a shift register or a decoder are integrally formed of polycrystalline Si or single-crystalline Si.
As an example of a liquid crystal display apparatus having such a structure, a projection-type liquid crystal display apparatus is known. In a typical system including the display apparatus, polarized-light is incident to the liquid crystal device to provide emitted light which has been modulated according to given display picture data, thereby enlarging and projecting the emitted light image for viewing. In such a liquid crystal display apparatus, it is a general practice to include a microlens array so as to provide an increased aperture ratio of the liquid crystal device (i.e., areal percentage of aperture given by pixel electrodes), as disclosed in Japanese Laid-Open Patent Application JP-A 8-114780, which discloses a microlens-equipped liquid crystal panel and a liquid crystal display apparatus including the panel. The microlens-equipped liquid crystal panel for this purpose is generally of a transmission type. An example structure thereof is shown in
FIG. 10
, wherein a liquid crystal layer
17
is disposed between a layer of pixel electrodes
18
and an array of microlenses
16
, and respective illumination lights of primary colors R, G and B are incident to the liquid crystal panel at respectively different angles so that the respective primary color lights are caused to enter respectively different pixels or pixel electrodes
18
, whereby a color filter layer is removed and an improved light utilization efficiency is realized. This type of projection display apparatus can achieve a bright full-color picture projection display using a single liquid crystal panel, and a commercial product thereof is gradually being introduced on the market.
FIG. 3
shows a basic optical system for a display apparatus including such a known microlens-equipped liquid crystal panel. Referring to
FIG. 3
, the display apparatus system includes a light source
201
, a dichroic mirror
202
of red (R), a dichroic mirror
203
of green (G) and a dichroic mirror
204
of blue (B) for selectively reflecting red, green and blue light fluxes, respectively, from the light source
201
, a liquid crystal panel or device
205
for modulating the light fluxes from the dichroic mirrors, a Fresnel lens
206
, a projection lens
207
, and a screen
208
. Parallel light emitted from the light source
201
is separated by the respective dichroic mirrors
202
,
203
and
204
into respective light fluxes of R, G and B, which are then incident to the liquid crystal device
205
. In the liquid crystal device
205
, voltages applied to the liquid crystal at the respective pixels of R, G and B are controlled to effect luminance modulation, depending on given picture data, and the emitted picture data-carrying light fluxes are passed through the Fresnel lens
206
for condensing the light fluxes and the projection lens
207
to be projected in an enlarged size onto the screen
208
.
FIG. 2A
shows an example of a color pixel arrangement pattern of such a liquid crystal device
205
equipped with microlenses, including microlenses
211
, and pixel electrodes
212
including color pixel electrodes
212
r,
212
g
and
212
b
corresponding to R, G and B, and each having an aperture
213
as shown in an enlarged size in FIG.
2
B. G-light separated and reflected by the dichroic mirrors is incident from an upper position of the microlens
211
vertically to the microlens
211
to be converged at a surface of a G-pixel (electrode)
212
. On the other hand, R-light and B-light are respectively incident to the microlens
211
with some angles and converged at the surfaces of R-pixel (electrode) and B-pixel (electrode), respectively, thereby providing somewhat distorted circular spots. Each color pixel may have a TFT-structure, e.g., as shown in FIG.
4
.
Each pixel shown in
FIG. 4
includes a TFT-structure, formed on glass
101
, including a gate
106
, a source region
150
connected to a data signal electrode, a drain region
103
accompanied by a lightly doped drain region
107
, a drain electrode
108
including laminated layers
108
a
and
108
b,
and a pixel electrode
508
connected to the drain electrode
108
. Opposite the TFT-substrate
101
, a counter substrate
621
(on which microlenses are arranged but are omitted from being shown) is disposed, including a black matrix mask
622
, for masking regions between adjacent pixels, and a transparent counter electrode
623
. The two substrates
101
and
621
are surfaced with alignment films
4010
and
221
so as to align a liquid crystal
611
disposed therebetween.
Such a known microlens-equipped liquid crystal panel is, however, found to be accompanied by problems as follows when the pixel size, i.e., the size of the apertures, is decreased so as to reduce the panel size. When the size of an aperture
213
is reduced relative to a spot diameter formed by condensation with a microlens
211
, the distortion of the spot diameter subtly affects the display characteristic. Particularly, when the sizes of the spot diameter and the aperture are nearly equal, part of the spot diameter can be larger than the aperture
213
size due to a spot diameter distortion caused by oblique light incidence, thus resulting in a lower light utilization efficiency. This affects the brightness and color balance. For obviating such difficulties accompanying lowered light utilization efficiency, pixel sizes are ordinarily based on a pixel requiring a larger aperture, whereby the entire device size is enlarged. If the liquid crystal panel size is e
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Ngo Julie
Sikes William L.
LandOfFree
Liquid crystal device or apparatus comprises pixels of at... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid crystal device or apparatus comprises pixels of at..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid crystal device or apparatus comprises pixels of at... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2923783