Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1998-09-09
2003-11-25
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S058000, C349S122000, C349S158000
Reexamination Certificate
active
06654083
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a electronic optical device, a projection type device using the same, and a method for producing the electronic optical device. In more detail, the present invention relates to a construction technology of the outer face of the two sheets of transparent substrates inside of which a liquid crystal is disposed, and a technology for forming the construction.
2. Description of Related Art
As shown in
FIG. 16
, the electronic optical device is mainly composed of an active matrix substrate
300
(a first transparent substrate) on which pixel electrodes and pixel switching elements are formed, an opposite substrate
400
(a second transparent substrate) on which opposite electrodes are formed, and one example of a electronic optical material, a liquid crystal (LC) disposed between the active matrix substrate
300
and opposite substrate
400
. The liquid crystal (LC) is filled in the area divided by the substrates with a seal layer
80
between the active matrix substrate
300
and the opposite substrate
400
. Alignment of the liquid crystal is controlled for each pixel between the active matrix substrate
300
and the opposite substrate
400
.
Accordingly, in the projection type device in which a electronic optical device having a construction as described above is used as a light valve, the light projected from a light source is condensed by a condenser optical system to guide the light to the electronic optical device and a desired image is projected with magnification on a projection plane such as a screen by a magnifying projection optical system after optically modulating the projected light with the electronic optical device.
Although the electronic optical device constructed as described above is usually mounted in a light-shielding case provided with an opening corresponding to the display area, contours of the display area are usually defined by the light-shielding film (referred to as a partitioning periphery hereinafter) made of Cr (chromium) and the like on the opposite substrate
400
. In other words, a design margin at the opening of the case is ensured by the width of the partitioning periphery since it is difficult for the edge of the opening of the case formed of a plastic and the like to have a sufficient dimensional accuracy due to the presence of burrs at the edge. According to this art, problems that the display area is hidden behind the opening of the case or the panel portion outside of the display area at the outer circumference of the partitioning periphery is exposed from the opening can be avoided when the opening of the case is formed with an accuracy enough for accommodating the opening of the case within the width of the partitioning periphery viewed from the front of the display area.
However, since the outer face
302
of the active matrix substrate
300
or the outer face
402
of the opposite substrate electrode
400
is only separated by the thickness of these transparent substrates, for example 1 mm, when viewed from the liquid crystal (LC), the light focusing on the liquid crystal (LC) is also focusing on flaws and dust adhered on the outer face of these transparent substrates. Consequently, flaws and dust as small as 10 to 20 &mgr;m are displayed in the projection image, deteriorating the image quality.
A partial temperature increase is liable to occur as a result of making the thickness of the active matrix substrate
300
and the opposite substrate
400
thin, because an intense light is illuminated from the light source to the electronic optical device in the projection type device The partial heated portion has a different transmittance from that of the surrounding area, thereby also deteriorating the image quality. Such partial temperature increase may be a cause to deteriorate the liquid crystal.
Japanese Unexamined Patent Publications No. 9-105901 and No. 9-113906 have proposed a construction as shown in
FIG. 17
, wherein a transparent substrate
102
is attached on the outer face
302
of the active matrix substrate
300
via an air layer (air) using a bonding material
101
, thereby suppressing a temperature increase of the electronic optical device by heat radiation from this transparent substrate
102
along with preventing flaws and dust from adhering on the outer face
302
of the active matrix substrate
300
owing to this transparent substrate
102
. However, boundary faces between the active matrix substrate
300
and the air layer, and between the air layer (air) and the transparent substrate
102
are added as new reflection boundary faces as a consequence of disposing the opposite transparent substrate
102
on the outer face
302
of the active matrix substrate
300
via an air layer (air) in the electronic optical device having the construction shown in
FIG. 17
, thereby increasing reflection at the boundary face. Accordingly, luminous energy loss is increased to cause a new problem that the projected image becomes dark in the electronic optical device with the construction shown in FIG.
17
. While it may be devised that a reflection preventing film is deposited in vacuum on the outer face
302
of the active matrix substrate
300
and on the inner face
104
of the transparent substrate
102
, forming such reflection preventing films requires much labor in a vacuum atmosphere, resulting in a large increase of the production cost of the electronic optical device. Disposing only a transparent substrate
102
on the outer face
302
of the active matrix substrate
300
cannot yet prevent dust from adhering on the outer face
302
of the active matrix substrate
300
. Consequently it has been impossible to perfectly prevent the display image quality from being deteriorated.
As hitherto described, there is a first problem that the dust-preventive function, de-focusing function and heat radiation function cannot be improved at once with a low production cost and good balance in the conventional electronic optical device.
In the field of current electronic optical devices, on the other hand, demands for making the panel small and fine, or demands for ensuring a large display area in a limited panel face have been increasing, forcing the necessity to narrow the width of the partitioning periphery provided at the opposite substrate as described previously. The width of the partitioning periphery is also required to be narrow, especially in adhering both substrates with an adhesive comprising an ultraviolet light curing type resin, so as not to block ultraviolet light irradiation from the outer face of the substrate because the seal area for bonding both substrates with an adhesive exists in the vicinity of the partitioning periphery. Consequently, there arises a second problem that the design margin at the opening portion of the case is reduced as the width of the partitioning periphery is narrowed in the art for ensuring the design margin of the opening portion of the case by using the width of the partitioning periphery.
Furthermore, there arises another problem that ghost images of the auxiliary circuits and elements provided in the panel are mixed with the projecting light depending on the angle of the incident light and projecting light, when the electronic optical device provided with the partitioning periphery is used for the projection type display device and the transmissive display device provided with a back light, especially when the width of the partitioning periphery is narrowed.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve the foregoing first problem, by providing a electronic optical device with a high image quality and a projection type device using the same, wherein flaws and dust are prevented from adhering on the transparent substrates, between which a liquid crystal is inserted, without significantly increasing the production cost by improving the construction of the outer faces of two sheets of transparent substrates for disposing a liquid crystal, along with suppressing temperature i
Saito Hiromi
Toda Shigeo
Chowdhury Tarifur R.
Seiko Epson Corporation
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