Liquid crystal display device having connecting means for connecting the transparent electrode of the compensating cell to ground potential for preventing exterior static electricity

A double-layered type super-twisted liquid crystal display device including a display cell and a compensating cell in a laminated structure with a spacer interposed therebetween wherein the compensating cell is arranged on the front surface side of the display device. The display cell is arranged on the rear surface side of the display device, and a light source for illuminating the display cell as well as a reflector are arranged on the rear surface side of the display cell. In addition, a transparent electrode is formed over the whole surface of at least one of glass substrates constituting the compensating cell. The transparent electrode is earthed via a clip pin which is held in a clamped state at the outermost end part of the transparent electrode.

BACKGROUND OF THE INVENTION 
1. Field Of The Invention 
The present invention relates generally to a liquid crystal device. More 
particularly, the present invention relates to a double-layered type 
super-twisted nematic liquid crystal display device including a display 
cell and a compensating cell in a laminated state. 
2. Description Of The Related Art 
To facilitate understanding of the present invention, a typical 
conventional double-layered type super-twisted nematic liquid crystal 
display device will briefly be described below with reference to FIG. 3. 
As shown in FIG. 3, the conventional display device is constructed such 
that a display cell 31 is superimposed on a compensating cell 3e in a 
layered structure with a spacer 33 interposed therebetween such that the 
display cell 31 is arranged on the front side of the display device. In 
addition, a light source 34 for illuminating the display cell 31 and a 
reflector 35 are arranged on the rear surface side of the compensating 
cell 32. 
The display cell 31 is provided with a common transparent electrode and a 
segment transparent electrode both of which are electrically connected to 
one terminal of a driver circuit 36 at the right-hand end of a substrate 
as seen in the drawing. 
Basically, since there is no need of feeding the compensating cell 32 with 
an electric current, any transparent electrode is not required for the 
compensating cell 32. In some case, however, a transparent electrode is 
formed over the whole surface of the substrate because of a necessity 
associated with a convenience of production. 
With respect to the conventional liquid crystal display device constructed 
in the above-described manner, it has been found that erroneous display 
takes place under the influence of exterior static electricity, since the 
display cell is arranged on the front surface side of the display device. 
When the display device is used under an environmental circumstance having 
a lower temperature, it is necessary that the display cell 31 is warmed up 
in order to assure that any delay of a response speed is prevented 
reliably. However, as long as the compensating cell 32 is arranged on the 
light source 34 side, there appears a problem that it is practically 
difficult to positively utilize heat generated by the light source 34 for 
the purpose of warming up the display cell 31. 
SUMMARY OF THE INVENTION 
The present invention has been made in consideration of the foregoing 
problem. 
Therefore, an object of the present invention is to provide a 
double-layered type super-twisted nematic liquid crystal display device 
which assures that an occurrence of erroneous display due to the influence 
induced by exterior static electricity is prevented reliably. 
Another object of the present invention is to provide a double-layered type 
super-twisted nematic liquid crystal display device which assures that a 
property of display responsiveness under an environmental circumstance 
having a lower temperature is improved substantially. 
The present invention provides a double-layered type super-twisted nematic 
liquid crystal display device including a display cell and a compensating 
cell in a laminated structure with a spacer interposed therebetween, 
wherein the compensating cell is arranged on the front surface side of the 
display device; the display cell is arranged on the rear surface side of 
the display device; a light source for illuminating the display cell as 
well as a reflector are arranged on the rear surface side of the display 
cell; and a transparent electrode is formed over the whole surface of at 
least one of glass substrates constituting the compensating cell, the 
transparent electrode being earthed. 
The compensating cell is preferably constructed in a laminated structure 
such that an orientation film is formed on the inner surface of a glass 
substrate on the front surface side of the display device, the transparent 
electrode is formed on the inner surface of a glass substrate on the rear 
surface side of the display device and another orientation film is formed 
on the inner surface of the transparent electrode so that a liquid crystal 
is filled in the space defined by the glass substrates and the spacer. 
The transparent electrode is earthed via a clip pin which is held in a 
clamped state on the outermost end part thereof projecting outside of the 
spacer while the transparent electrode and the glass substrate are clamped 
by the clip pin. 
According to the present invention, since the compensating cell arranged on 
the front surface side of the display device is provided with the 
transparent electrode which is earthed via the clip pin, an occurrence of 
erroneous display due to the influence induced by exterior static 
electricity can be prevented reliably. In addition, with the display 
device of the present invention, it is easy to positively utilize heat 
generated by the light source for the purpose of warming up the display 
cell, a property of display responsiveness under an environmental 
circumstance having a lower temperature can be improved remarkably. 
Other objects, features and advantages of the present invention will become 
apparent from reading of the following description which has been made in 
conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Now, the present invention will be described in detail hereinafter with 
reference to FIG. 1 and FIG. 2 which illustrate a preferred embodiment of 
the present invention. 
As shown in the drawings, a double-layered type liquid crystal display 
device in accordance with the embodiment of the present invention is 
constructed such that a compensating cell 2 is superimposed on a display 
cell 1 in a laminated structure with a spacer 3 interposed therebetween 
and a light source 4 for illuminating the display cell 1 as well as a 
reflector 5 are arranged on the rear surface side of the display cell 1. 
It should be noted that the compensating cell 2 is arranged on the front 
surface side of the display device. One terminal of a driver circuit 6 is 
electrically connected to the left-hand end of the display cell 1 as seen 
in FIG. 1. In addition, a polarizing plate 7 is adhesively secured to the 
rear surface of the display cell 1, while another polarizing plate 8 is 
adhesively secured to the front surface of the compensating cell 2. 
As best seen in FIG. 2, the compensating cell 2 is constructed such that a 
transparent electrode 22 is formed over the whole surface of one of glass 
substrates 21A and 21B each constituting the compensating cell 2, e.g., 
the glass substrate 21B located on the display cell 1 side, an orientation 
film 23A is formed on the inner surface of the glass substrate 21A and 
another orientation film 23B is formed on the inner surface of the 
transparent electrode 22 so that the space defined between the both 
orientation films 23A and 23B and the spacer 25 is filled with a liquid 
crystal 24. The right-hand end of the glass substrate 21B is held by a 
clip pin 9 in a clamped state so as to allow the transparent electrode 22 
to be earthed or grounded via the clip pin 9. 
With such construction, since the compensating cell 2 is arranged on the 
front surface side of the display device, and the transparent electrode 22 
formed over the whole surface of the glass substrate 21B is earthed or 
grounded via the clip pin 9, the liquid crystal display device is not 
undesirably influenced by exterior static electricity, resulting in an 
occurrence of erroneous display due to the influence induced by the 
exterior static electricity being prevented reliably. 
In addition, since the display cell 1 is arranged on the light source 4 
side, this makes it easy to positively utilize heat generated by the light 
source 4 for the purpose of warming up the display cell 1. Warming-up of 
the display cell 1 in this way contributes to remarkable improvement of a 
property of display responsiveness under an environmental circumstance 
having a lower temperature. 
It should be emphasized that the transparent electrode 22 in the 
compensating cell 2 is formed over the whole surface of at least one of 
the glass substrates 21A and 21B. 
As is apparent from the above description, according to the present 
invention, the compensating cell is superimposed on the display cell in a 
laminated structure such that the compensating cell is arranged on the 
front surface side of the display device. This makes it easy to positively 
utilize heat generated by the illuminating light source for the purpose of 
warming up the display cell. Consequently, a property of display 
responsiveness of the display device under an environmental circumstance 
having a lower temperature can be improved remarkably. Additionally, since 
the transparent electrode is formed over the whole surface of at least one 
of the glass substrates and moreover it is earthed or grounded via the 
clip pin, an occurrence of erroneous display due to the influence induced 
by exterior static electricity can be prevented reliably. 
While the present invention has been described above with respect to a 
single preferred embodiment thereof, it should of course be understood 
that the present invention should not be limited only to this embodiment 
but various changes or modifications may be made without departure from 
the scope of the invention as defined by the appended claims.