Liquid crystal cells – elements and systems – Particular structure – Holder – support – frame – or housing
Reexamination Certificate
1999-10-01
2001-07-24
Dudek, James A. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Holder, support, frame, or housing
C349S060000
Reexamination Certificate
active
06266107
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a fixing structure for a picture display unit of an illumination-type picture display apparatus, such as a rear projection display apparatus for an audio-visual system, and a data projector for displaying computer output data.
A conventional color liquid crystal projector using liquid crystal panels has included a plurality of liquid crystal panels in order to display a high quality picture, whereby the plurality of liquid crystal panels are illuminated with primary color light fluxes formed by color separation and the light fluxes emitted from the liquid crystal panels are color-synthesized to display a color picture.
In this way, in the conventional system, the respective color liquid crystal panels are respectively screwed to movable stages without a particular positional alignment, and the positions of the movable stages are then adjusted so as to achieve adequate superposition of the respective color pictures to form a multi-color picture. Thereafter, in the adjusted positions, the movable stages are fixed, e.g., with a bonding agent.
However, as the respective liquid crystal pannels used for color synthesis are fixed onto the movable stages, the deviation or alignment failure among the liquid crystal panels is liable to occur not only in case where the movable stages are not sufficiently fixed but also in case where the movable stages are sufficiently fixed.
In recent years, a small-size liquid crystal panel accompanied with a small optical system is becoming used in order to provide a smaller projection apparatus, and on the other hand, a higher resolution has been demanded. For complying with such demands on the market, there is an increasing demand for a small-size high-resolution liquid crystal panel. However, a small-size high-resolution liquid crystal panel is necessarily required to have a smaller pixel size which has been reduced down to several &mgr;m to ten and several &mgr;m.
If one pixel size is reduced to such a small size, it becomes impossible to ignore a minute play or an elongation or shrinkage corresponding to a temperature change of a movable stage as a source of liquid crystal panel alignment failure. For this reason, instead of the method of alignment by positional adjustment of a movable stage on which a liquid crystal panel is fixed, there has been adopted a method where each liquid crystal panel is directly fixed onto a holder for alignment separate from a projection optical system, the position alignment of each liquid crystal panel is effected by the holder, and the respective panels are directly fixed onto panel-fixing frames in a projection optical system by means of solder or other bonding agents.
FIGS. 4A and 4B
illustrate an example of the panel-fixing method. Referring to
FIGS. 4A and 4B
, a holder plate
12
on which a liquid crystal panel
11
is fixed has a fixing region FX, at which a panel-fixing frame
13
is fixed with solder
14
, such as creamy solder or thread solder.
In the solder fixing system, it is necessary to melt the solder while retaining the alignment of each liquid crystal panel and heat the solder fixing region FX while retaining the alignment state. For this purpose, non-contact heating is preferred, and creamy solder is preferred to thread solder because of easier melting. Creamy solder is also preferred because it has a smaller heat expansion coefficient and it readily melts on re-heating, thus allowing re-adjustment of the alignment by re-heating.
Accordingly, it has been practiced to apply creamy solder at the solder fixing region FX and heating the region by light-beam heating as a non-contact heating method to form a solder fixed liquid crystal panel unit as shown in
FIGS. 4A and 4B
.
However, in the above-mentioned process, as is understood from the sectional view of
FIG. 4A
, the creamy solder is sandwiched between the panel holder substrate
12
and the panel-fixing frame
13
at the solder fixing region FX, and a flux contained in the sandwiched creamy solder is evaporated on temperature increase under heating, whereby solder is liable to be scattered out of the solder fixing region due to the evaporation of the flux to soil the panel and other optical devices close thereto if the panel holder is in a flat sheet form at the solder fixing region FX.
During the soldering, the melted solder also wets sides of the holder plate
12
at the solder fixing region due to its surface tension to increase the resultant fixing strength. However, if the holder plate
12
is in a flat sheet form at the solder fixing region FX, the side wall portions of the holder plate
12
to be wetted by the melted solder is small in area.
The above-problems occur in fixing structures of not only liquid crystal panels but also other display panels.
SUMMARY OF THE INVENTION
In view of the above-mentioned problems, a principal object of the present invention is to provide a display panel-fixing structure capable of preventing the scattering of solder at a solder-fixing region of fixing an aligned display panel unit.
Another object of the present invention is to provide a display panel-fixing structure exhibiting an improved soldering strength at a solder-fixing region of fixing an aligned display panel unit.
According to the present invention, there is provided a display panel-fixing structure, comprising a holder plate holding a display panel, a panel-fixing frame for fixing the display panel, and a bonding agent bonding the holder plate and the panel-fixing frame at a fixing region where the holder plate and the panel-fixing frame is superposed with each other, wherein at least one of the holder plate and the panel-fixing frame is provided with an opening or cut at the fixing region.
Because of the presence of the opening or cut in at least one of the holder plate and the panel-fixing frame at the fixing region, the flux or vaporizable component of the bonding agent, typically solder, sandwiched between the holder plate and the panel-fixing frame can be effectively evaporated through the opening or cut, thereby suppressing the scattering of the solder around the fixing region, and the opening or cut provides an additional wall area to be wetted with the solder, thereby increasing the soldering strength at the fixing region.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5587817 (1996-12-01), Miyamoto et al.
Canon Kabushiki Kaisha
Dudek James A.
Fitzpatrick ,Cella, Harper & Scinto
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