Liquid crystal cells – elements and systems – Liquid crystal system – Liquid crystal writing tablet
Reexamination Certificate
2000-06-29
2004-11-02
Nguyen, Dung (Department: 2871)
Liquid crystal cells, elements and systems
Liquid crystal system
Liquid crystal writing tablet
C349S158000
Reexamination Certificate
active
06812974
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to liquid crystal devices for displaying various images, e.g., letters, figures, and drawings, by controlling alignment of liquid crystal enclosed between a pair of substrates, and particularly, to a liquid crystal device provided with an input unit such as a touch panel.
2. Description of the Related Art
With the spread of compact electronic information devices, such as personal digital assistants and palmtop computers, liquid crystal devices capable of input operations provided with transparent input sections overlaid thereon have been widely used.
As shown in
FIG. 12
, a known liquid crystal device capable of input operations is formed by bonding an input unit
94
including a flexible front substrate
94
a
and a back substrate
94
b
bonded to the front substrate
94
a
with a sealant
99
, to a liquid crystal panel
92
, including a first substrate
92
a
and a second substrate
92
b
bonded to the first substrate
92
a
with a sealant
93
.
In this liquid crystal device, an image formed in the liquid crystal panel
92
is visible through the transparent input unit
94
. When the outer face of the input unit
94
, that is, the outer face of the front substrate
94
a
, is pressed with an input tool (a pen or a rod with a sharp tip), information on the location of the pressed portion is input.
However, in the conventional liquid crystal device capable of input operations, the input portion is locally deformed when the surface of the input unit
94
is pressed with the tip of the input tool. The deformation generates slight deflection in the first substrate
92
a
of the liquid crystal panel
92
which is stacked on the input unit
94
. Since the gap between the substrates of the liquid crystal panel
92
, that is, the cell gap, is at most 5 to 10 &mgr;m, slight deflection of the first substrate
92
a
causes a significant localized change in the cell gap of the liquid crystal panel
92
, resulting in a distortion pattern in the image displayed in the liquid crystal device.
Since the back substrate
94
b
of the input unit
94
is composed of a hard material such as glass, the device becomes heavy as the input unit
94
becomes thick. Thus, decreased thickness and weight of the device are barely achieved. The liquid crystal device having such problems inhibits trends toward decreasing the size and weight of portable electronic equipments.
SUMMARY OF THE INVENTION
Accordingly, the present invention solves the above problems. An object of the present invention is to reduce distortion of displayed images due to pressing operations of the input unit. Another object of the present invention is to achieve the configuration of a thin and lightweight liquid crystal device capable of input operations.
The present invention is characterized by a liquid crystal device comprising: a liquid crystal panel comprising a first substrate, a second substrate opposing the first substrate and having flexibility, and a liquid crystal layer disposed therebetween; and an input unit arranged at a position which lies at a position overlapping the liquid crystal panel in plan view at the first substrate side; wherein a gap is provided on a side of the second substrate away from the liquid crystal layer.
Also, the present invention is characterized by a liquid crystal device comprising: a liquid crystal panel comprising a first substrate, a second substrate opposing the first substrate and having flexibility, and a sealant and a liquid crystal layer disposed therebetween; an input unit arranged at a position which lies at a position overlapping the liquid crystal panel in plan view at the first substrate side; and a supporting section arranged at a position away from the liquid crystal layer of the second substrate; wherein the supporting section is arranged at a position corresponding to a region for forming the sealant.
The second substrate having flexibility is provided so as to be readily deflected along with the deflection of the first substrate. That is, the gap is provided on a side of the second substrate away from an image observing side, or the supporting section is arranged at a position corresponding to a region for forming the sealant.
When the a pressing operation is performed on the input unit, the first substrate is locally deflected by the pressing operation. The second substrate having flexibility is readily deflected along with the deflection of the first substrate. As a result, a localized change in the cell gap of the liquid crystal panel is suppressed.
When a position detecting element is disposed between the front-side substrate and the back-side substrate in the input unit and when the back-side substrate is directly or indirectly stacked on the first substrate, the input unit has a structure in which the position detecting element is disposed between these two substrates. Thus, this device can be produced by independently producing the input unit and the liquid crystal panel and by stacking them. Thus, the productivity and the yield of the device can be improved. Since the two substrates arranged on both sides of the position detecting element are flexible, the thickness and the weight of the input unit can be reduced.
Preferably, the second substrate has higher flexibility than that of a structure disposed between the position detecting element of the input unit and the liquid crystal of the liquid crystal panel. When the structure includes a plurality of components and when one component has significantly lower flexibility compared to the other components (for example, significantly thicker or significantly harder than those of the others), the flexibility of this structure may be substantially the same as the flexibility of the component having the least flexibility. This component may be the first substrate, or the back-side substrate when the back-side substrate opposing the front-side substrate with the position detecting means therebetween is provided in the input unit, or the illumination means (for example, a light guide plate) when the illuminating means for illuminating the liquid crystal panel is provided between the input unit and the liquid crystal panel. The pressure applied to the input unit by the pressing operation is absorbed by the above structure or the above member having hardness or low flexibility. The localized deflection of the above structure or the above member caused by the stress of the pressing operation to the input unit is suppressed by some extent due to the low flexibility thereof, but the deflection acts toward a localized change in the cell gap of the liquid crystal panel. Since the second substrate has higher flexibility than that of the structure or the member, the second substrate is also deflected in response to the deflection of the structure or the member so as to suppress a localized change in the cell gap.
Herein, “flexibility” means a mechanical property causing relatively large deflection when a pressure (for example 0.5 to 5 N), which is generated when an operator puts an input tool into contact with a component, is applied. “Relatively large deflection” in this case means a deflection which is the same or more than that of the cell gap of the liquid crystal panel (for example, 5 to 10 &mgr;m or more). The flexible second substrate is effective for suppressing the display distortion of the liquid crystal panel caused by the pressing operations to the input unit. In contrast, the first substrate and the above member are preferably “hard” or “less flexible”. Herein “hard” or “less flexible” means a property causing a deflection (for example, 0.1 to 3 &mgr;m or less) corresponding to a change in the cell gap which causes a change in the display state of the liquid crystal panel but not causing a deflection larger than the change in the cell gap when a pressure (for example 0.5 to 5 N), which is generated when an operator puts an input tool into contact with a component, is applied.
In addition, the supporting section is provided so as to
Fujisawa Shinji
Hinata Shoji
Hosogaya Hiroyuki
Imazeki Yoshikatsu
Harness & Dickey & Pierce P.L.C.
Nguyen Dung
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