Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2002-05-22
2002-12-24
Ben, Loha (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S246000, C359S252000, C359S253000, C359S265000, C359S273000, C359S323000, C349S042000, C349S074000, C349S149000
Reexamination Certificate
active
06498672
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electro-optical device and a projection display device including the same.
2. Description of Related Art
In general, a liquid crystal panel used in a projection display device, such as a liquid crystal projector, is mounted to the inside of a housing of the projection display device, with the liquid crystal panel being accommodated in a case member formed of, for example, synthetic resin. Usually, a flexible wiring substrate is connected to the liquid crystal panel. With the flexible wiring substrate being connected, the liquid crystal panel is installed and positioned in the case member in order to affix it to the case member with, for example, an adhesive or a holding fixture, after which a mounting hole or the like formed in the case member is positioned at a mounting portion formed inside the projection display device and secured thereto by a method such as screwing.
A liquid crystal panel module used as an electro-optical device including the above-described liquid crystal panel and case member is used as a light valve for forming a predetermined image as a result of receiving light from a light source in the projection display device. The image formed by the liquid crystal panel module is enlarged by a projection optical system of the projection display device, and the enlarged image is projected onto, for example, a screen.
FIG. 1
is an exploded perspective view of a conventional liquid crystal panel module, while
FIG. 2
is a schematic view showing in section the general structure of the conventional liquid crystal panel module. The liquid crystal panel module may consist of a liquid crystal panel
10
and a case member
20
for accommodating the liquid crystal panel
10
therein. In order to form the liquid crystal panel
10
, an element substrate
11
and an opposing substrate
12
, both of which are formed of glass or the like, are placed with a predetermined space formed therebetween in order to bond them together with a sealant
14
. After the bonding of the substrates
11
and
12
, liquid crystals
10
a
are injected between the substrates. The case member
20
is formed, of, for example, synthetic resin, which is black or any other color possessing light-shielding capability.
In the liquid crystal panel
10
, an active element such as a known TFT (thin-film transistor) element, a pixel electrode formed of a transparent electrical conductor such as an ITO (indium tin oxide) conductor, wiring, an alignment layer, etc., are formed on the inside surface of the element substrate
11
. A known opposing electrode, an alignment layer, etc., are formed on the inside surface of the opposing substrate
12
. Thus, an active matrix type liquid crystal panel structure is formed. A light-shielding layer
12
a
serving as a frame defining a light-transmissive area (or an effective display area) of the liquid crystal panel
10
is formed at an outer peripheral portion of the inside surface of the opposing substrate
12
.
In the projection display device, the liquid crystal panel module is irradiated with gathered and concentrated light, and the light is either transmitted or blocked by a plurality of pixels formed in the effective display area of the liquid crystal panel in order to form a predetermined image. Each pixel is controlled by an electric field applied as a result of an electrical potential difference between the pixel electrode and the opposing electrode. Here, when there are any scratch defects or dust on the outside surface of either the element substrate
11
or the opposing substrate
12
of the liquid crystal panel
10
, the scratch defects or dust disturb the image, resulting in the problem that the quality of the projected image is reduced. Since the image formed by the liquid crystal panel
10
is enlarged and projected, this problem is particularly serious, so that the aforementioned scratch defects or dust considerably adversely affect the image.
In order to overcome this problem, a method in which transparent substrates
1
and
2
are adhered to outside surfaces of the element substrate
11
and the opposing substrate
12
of the liquid crystal panel
10
, respectively, has, hitherto, been developed. The transparent substrates
1
and
2
are adhered to the element substrate
11
and the opposing substrate
12
, respectively, with a transparent adhesive which is not shown. For the transparent adhesive, it is preferable to use a material whose refractive index is approximately equal to those of the element substrate
11
and the opposing substrate
12
and those of the transparent substrates
1
and
2
. Examples of the transparent adhesive are silicone adhesive and acrylic adhesive, which are transparent after hardening. Accordingly, by adhering the transparent substrates
1
and
2
to the outside surfaces of the element substrate
11
and opposing substrate
12
using a transparent adhesive, the quality of the image is not affected even if there are any scratch defects on the outside surfaces of the element substrate
11
and the opposing substrate
12
, and dust is prevented from sticking onto the outside surfaces of the element substrate
11
and the opposing substrate
12
. Although scratch defects may be formed or dust may stick onto the outside surfaces of the transparent substrates
1
and
2
, the focus of light radiated from the light source is usually set so as to be situated in the liquid crystal panel
10
, so that, due to a defocusing effect, the image quality is virtually unaffected.
The case member
20
includes a hole
20
a
which extends through the top and bottom thereof so as to accommodate the liquid crystal panel
10
. The hole
20
a
includes open sections
20
b
and
20
c
formed at both the front and back sides of the accommodated liquid crystal panel
10
. An inwardly protruding edge
21
is formed at an edge of the open section
20
c
so as to engage the outside surface of the transparent substrate
2
accommodated in the hole
20
a.
A holding frame
24
, which is stopped by an engaging protrusion
23
formed at the outside surface of the case member
20
, is mounted at the open section
20
b
in order to hold the outside surface of the transparent substrate
1
accommodated in the hole
20
a.
A step
22
is formed at the middle of the hole
20
a
in accordance with the outside shape of portions of the element substrate
11
protruding outwardly of the opposing substrate
12
of the liquid crystal panel
10
.
In assembling the liquid crystal panel module, after adhering the transparent substrates
1
and
2
to the front and back sides of the liquid crystal panel
10
, an adhesive whose main component is, for example, silicone rubber is applied to the protruding portions of the element substrate
11
and the inside of the case member
20
, and, from the open section
20
b
in the case member
20
, the liquid crystal panel
10
and the transparent substrates
1
and
2
are placed into the case member
20
. At this time, in the direction in which the liquid crystal panel
10
and the transparent substrates
1
and
2
are placed (that is, the thickness direction of the panel), the liquid crystal panel
10
and the transparent substrates
1
and
2
are positioned as a result of bringing the outside surface of the transparent substrate
2
and the protruding edge
21
into contact with each other. In the direction of extension of a surface of the liquid crystal panel
10
, they are positioned as a result of bringing an end of the opposing substrate
12
and the inside surface defining the hole
20
a
into contact with each other. Lastly, the holding frame
24
is fitted to the engaging protrusion
23
in order to hold the panel assembly so that it does not get dislodged from the open section
20
b,
and then the adhesive is allowed to harden in order to form an integral structure.
In a projection display device including the above-described conventional liquid crystal panel module, due to restrictions on the structure of the device or d
Ben Loha
Seiko Epson Corporation
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