Liquid crystal cells – elements and systems – Particular structure – Interconnection of plural cells in parallel
Reexamination Certificate
1996-03-20
2002-06-04
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Interconnection of plural cells in parallel
C349S158000, C349S187000
Reexamination Certificate
active
06400428
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a display device for use in AV (audio visual) equipments or OA (office automation) equipments.
BACKGROUND OF THE INVENTION
Recently, there has been an increasing demand for home TV sets representing AV equipments and display devices for use in OA equipments of improved characteristics such as light weight, thin structure, low power consumption, high definition performance and large screen, etc. To meet these demand, the development of display devices such as a CRT (cathode ray tube) display, an LCD (liquid crystal display), a PDP (plasma display panel), an EL (electro luminescent) display, and an LED (light emitting diode) display has been made to achieve improved characteristics thereof, and some of the display devices of improved characteristics have already been used in practical applications.
Especially, the home AV equipments are more and more demanded for amusement purposes. The current home AV equipments' market also shows that a consumer's demand is gradually shifted to a larger screen thanks to a reduction in per inch cost. The introduction of the stereophonic sound system also requires home AV equipments to have large screens.
In the business world, there has been an increasing demand for display devices of improved characteristics that offer high visibility effect with easy handling, such as improved brightness not only in still image but also in moving image, that can be suitably used in presentation performance using a computer, etc. To respond to such demand for the described improved characteristics in the business world, a development of display devices of larger screen has been still more expected.
Among such display devices, liquid crystal display devices can be installed even in a small space with ease because of its beneficial features being lighter weight, narrower width, thinner structure than other display devices. Moreover, for other beneficial characteristics of low power consumption and being evolvable into full-color display with ease, the liquid crystal display' market has been expanded in various fields recently and the development of large-screen liquid crystal display devices has been more strongly demanded than other display devices.
However, when the screen of the liquid crystal display is upsized, as a defect image becomes more noticeable under the same resolution per screen, improvements in the resolution is necessary to achieve quality images of a video source. In the liquid crystal display device, an image is formed by display elements that are integrally formed and can be controlled independently, and thus to increase the number of display elements is inevitable to achieve an improved resolution.
However, the reduction in percent defective of each display element in the manufacturing process already faces the limit, and a significant progress is difficult to be expected.
Namely, to produce a greater number of display elements to meet the demand for the liquid crystal display device of a large screen would accelerate a drop in yield of the display device as a whole. Thus, it would be difficult to mass-produce the liquid crystal display device of a large screen which offers high quality images, and a cost for such liquid crystal display device remains too high.
To overcome the described difficulties, as shown in
FIG. 2
of the present embodiment, a method of upsizing a screen using a so-called multi-panel display system has been proposed wherein an image is displayed on a large screen formed by joining plural liquid crystal display panels together. By adopting such system, even with the same percent defective of a single display element, as the defect is dispersed entirely on the display device, an overall improvement of a yield of the liquid crystal display device of a large screen which offers high quality images can be achieved while suppressing an increase in per unit area cost.
When forming a liquid crystal display device of a multi-display system, for example, as shown in FIG.
12
(
a
), liquid crystal panels
52
are joined together. Specifically, the plural liquid crystal panels
52
are joined together so as to be adjacent to one another on a surface of a reinforcing substrate
53
to enable a liquid crystal display device of a still larger screen.
However, when joining plural liquid crystal display panels
52
together to enable such liquid crystal display device of a large screen, if an end surface portion
52
c
of the liquid crystal panel
52
contacts a medium of different index of refraction (air, etc.), light refraction would occur. Besides, if the end surface portion
52
c
becomes coarse in the manufacturing process, refraction and scattering of light would occur, thereby presenting the problem that the joint between the liquid crystal panels
52
stands out.
In consideration of the above problems, it is preferable that a hardened bonding agent used in bonding the liquid crystal panels
52
to the reinforcing substrate
53
has the same index of refraction as a hardened bonding agent used in joining the liquid crystal panels
52
together and that the index of refraction of these hardened bonding agents is substantially equal to the index of refraction of the reinforcing substrate
53
and substrates which constitute the liquid crystal panel
52
, etc. By arranging so, refraction and scattering of light can be suppressed.
However, as shown in FIG.
12
(
b
), in the case of adopting the bonding agent
59
under the described condition, a crack
59
a
may generate along the edge of the liquid crystal panels
52
. This is because along an edge
52
a
(see FIG.
12
(
a
)) of the liquid crystal panels
52
, as stress concentrates by the curing shrinkage of the bonding agent
59
, a crack
59
a
may be generated or may be expanded even with a small impact. When light passes through such crack
59
a
, light scattering would occur, which again makes the joint between the liquid crystal panels
52
stand out.
With the described curing shrinkage, a partial pealing
59
b
occurs between the end surface portion
52
c
of the connected part of the liquid crystal panels
52
and the bonding agent
59
, which would cause the light scattering.
Additionally, when the face precision of the end surface portion
52
c
is low, since the bonding agent
59
is not spread entirely on the irregularity of the end surface portion
52
c
, fine bubbles may remain in the space between the end surface portion
52
c
of the liquid crystal panel
52
and the bonding agent
59
. Such fine bubbles remaining in the space may again cause a scattering of light.
Namely, to display a natural image on a large screen, it is required to prevent an occurrence of light scattering, for example, by preventing a generation of the crack
59
a
, the peeling
59
b
or bubbles as this makes the joint between the liquid crystal panels
52
noticeable.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a display device of a large screen formed by joining plural panels together which offers a natural image without generating light scattering at a connected part of the panels.
To fulfill at least the above-mentioned object, an example display device in accordance with the best presently contemplated embodiment of the present invention includes:
plural display panels, adjoining display panels being connected with each other by means of a bonding agent so as to have a single display screen,
wherein at least one edge portion of an end surface of a connected part of each display panel is chamfered.
In the display device having the described arrangement, a space between adjoining display panels is filled with the bonding agent, and when joining the display panels together, a concentration of the internal stress caused by a curing shrinkage of the bonding agent is suppressed at the chamfered edge portion. Namely, at such edge portion, as a maximum value of the internal stress becomes smaller than an intermolecular bond strength of the bonding agent, a generation of cracks aroun
Conlin David G.
Daley, Jr. William J.
Dike, Bronstein, Roberts & Cushman, Intellectual Property Practi
Parker Kenneth
Sharp Kabushiki Kaisha
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