Tablet integrated liquid crystal display apparatus with less parallax

In a tablet integrated type liquid crystal display apparatus, a first transparent substrate is provided on a view side. The first substrate is a plastic substrate having a thickness equal to or thinner than 0.6 mm, and a counter electrode is formed on the first substrate. A second substrate on which a driving layer composed of switching elements and pixel electrodes respectively connected to the switching elements is formed. The second substrate is a glass substrate having a thickness in a range of 0.6 mm to 1.1 mm. A guest host liquid crystal layer sandwiched by the first substrate and the second substrate such that the guest host liquid crystal is driven by a voltage applied between the counter electrode and the pixel electrode. A tablet electrode layer may be provided between the first substrate and the counter electrode. Alternatively, a tablet electrode layer may be provided on the first substrate on an opposite side of the counter electrode. In this case, a protecting film is provided on the tablet electrode layer. In addition, a tablet electrode layer may be provided between the second substrate and the driving layer such that the tablet electrode layer is isolated from the driving layer.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a liquid crystal display apparatus and 
more particularly to a tablet integrated liquid crystal display apparatus 
in which a tablet input apparatus and a liquid crystal display apparatus 
are integrated. 
2. Description of Related Art 
The apparatus that a tablet input apparatus and a display apparatus are 
unified is known as an input apparatus to input an instruction or data to 
a computer. In this apparatus, the instruction or data is inputted by 
directly touching the tablet input apparatus. 
For example, as shown in FIG. 1, a display apparatus 12 and a tablet 13 are 
formed independently, and they are made as a unitary apparatus. In this 
example, as a display apparatus, a liquid crystal display apparatus is 
used, and as a tablet, a resistive film type tablet is used in which a 
small gap is provided between two resistive film sheets connected to a 
power supply and current flowing when an input pen 1 is used to contact 
the two resistive film sheets each other is detected so that the contact 
position is detected. 
Next, FIG. 2 is a cross sectional view illustrating the structure of the 
tablet integrated type liquid crystal display apparatus shown in FIG. 1. 
In FIG. 2, a reference numeral 15 is a tablet, 16 and 17 are a set of 
polarizers, 18 and 19 are an opposing glass substrate and a thin film 
transistor (TFT) glass substrate, and 20 is a twisted nematic type 
(hereinafter, to be referred to as a "TN type") liquid crystal. A 
reference numeral 21 is a backlight which functions as a light source. 
In a conventional active matrix driving type liquid crystal display 
apparatus, glass substrates having the thickness of about 0.6 to 1.1 mm 
are used as the substrates which sandwich the liquid crystal. Therefore, 
there is a problem in that the conventional liquid crystal display 
apparatus is heavy because the thick glass substrate is used. However, it 
is difficult to make the thickness of the glass substrate thin in the 
viewpoint of mechanical strength. 
On the other hand, in a case where a pen input type screen input apparatus 
is combined with such a liquid crystal display apparatus, when an 
instruction or data is inputted by contacting the input pen 14 with the 
screen input apparatus, there is a problem in that the thickness of the 
viewing-side glass substrate directs a parallax between a tip of an input 
pen 14 and a liquid crystal display image so that it is not easy to input 
the instruction or data. In order to eliminate the parallax, if film 
substrates having the thickness of about 0.1 mm are used, when a film is 
deposited on the substrate on which switching elements are formed, there 
is a case that the substrate bends due to stress because the substrate is 
thin. Also, there is another problem in that the substrate is bent on 
handling it so that the switching elements are damaged. 
Generally, in a display apparatus using a TN liquid crystal, when the layer 
width of the TN liquid crystal is changed due to external force, the angle 
of torsion of the TN liquid crystal is changed at the portion where the 
external force is applied, such that the transmissivity remarkably 
changes. Therefore, in a case where a tablet integrated liquid crystal 
display apparatus is fabricated to have the structure shown in FIG. 2 
using the TN liquid crystal, there is a problem in that, when the input 
pen 14 is pushed to the tablet 15 for input of an instruction or data, the 
layer width of the TN liquid crystal is changed at the portion where the 
input pen 14 is pushed and the peripheral portion, so that the 
transmissivity changes there. As a result, the display quality is degraded 
there. 
In order to solve this problem, as shown in FIG. 3, a method is known in 
which a transparent glass or plastic protecting board 23 is inserted 
between the tablet 15 and the liquid crystal display apparatus 22 to 
prevent influence to the liquid crystal display apparatus 22 due to the 
force by the input pen 14. However, in order to prevent the layer width of 
the liquid crystal in the display apparatus 22 in a case of using this 
method, it is necessary that the protecting board 23 is not deformed due 
to the pushing force. For this reason, the protecting board needs to be 
thick and firm. As a result, there is a problem in that the tablet 
integrated type liquid crystal display apparatus becomes heavy and thick. 
Also, because the distance between the tip of the input pen 14 and a 
liquid crystal display image is widened to several mm or more, there is a 
problem of the parallax that the image is displayed on the position which 
is different from the tip of the input pen 14. 
SUMMARY OF THE INVENTION 
Therefore, an object of the present invention is to provide a tablet 
integrated type liquid crystal display apparatus in which the parallax 
between the tip of an input pen and a display image is eliminated without 
occurrence of the bending of a substrate and the damage of a switching 
element. 
In order to achieve an aspect of the present invention, a tablet integrated 
type liquid crystal display apparatus includes a first transparent 
substrate provided on a view side, wherein the first substrate has a 
thickness equal to or thinner than 0.6 mm, and wherein a counter electrode 
is formed on the first substrate, a second substrate on which a driving 
layer composed of switching elements and pixel electrodes respectively 
connected to the switching elements is formed, and guest host liquid 
crystal layer sandwiched by the first substrate and the second substrate 
such that the guest host liquid crystal is driven by a voltage applied 
between the counter electrode and the pixel electrode. 
In the tablet integrated type liquid crystal display apparatus, a tablet 
electrode layer may be provided between the first substrate and the 
counter electrode such that the tablet electrode layer is isolated from 
the counter electrode. Alternatively, a tablet electrode layer may be 
provided on the first substrate on an opposite side of the counter 
electrode. In this case, it is preferable that a protecting film is 
provided on the tablet electrode layer. In addition, a tablet electrode 
layer may be provided between the second substrate and the driving layer 
such that the tablet electrode layer is isolated from the driving layer. 
The tablet integrated type liquid crystal display apparatus may be a 
transmission type or a reflection type. In case of the reflection type, 
the pixel electrodes functions as reflecting plates in addition to the 
driving of the guest host liquid crystal. Also, it is preferable that the 
first substrate is a plastic substrate and the second substrate is a glass 
substrate having a thickness in a range of 0.6 mm to 1.1 mm. 
In order to achieve another aspect of the present invention, a tablet 
integrated type liquid crystal display apparatus includes a first 
transparent substrate provided on a view side, wherein a counter electrode 
is formed on the first substrate, a second substrate on which a driving 
layer composed of switching elements and pixel electrodes respectively 
connected to the switching elements is formed, a plurality of insulative 
supports provided between the first substrate and the second substrate to 
prevent the first substrate from being bent, and liquid crystal layer 
sandwiched by the first substrate and the second substrate such that the 
liquid crystal is driven by a voltage applied between the counter 
electrode and the pixel electrode.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Next, the tablet integrated type liquid crystal display apparatus of the 
present invention will be described with reference to the accompanying 
drawings. 
First, a tablet integrated type liquid crystal display apparatus according 
to the first embodiment of the present invention will be described. FIG. 4 
is a cross sectional view of the structure of the tablet integrated type 
liquid crystal display apparatus in the first embodiment. In the first 
embodiment, a twisted nematic (TN) liquid crystal is used for a 
transmission type display apparatus. The TN liquid crystal is driven by 
thin film transistors (TFTs) in an active matrix system. 
Referring to FIG. 4, a TFT substrate 19 is composed of a glass substrate 
having the thickness of 0.6 to 1.1 mm. On a surface of the TFT substrate 
19, a plurality of gate bus lines and a plurality of drain bus lines are 
arranged in a lattice manner by a usual process for producing a TFT 
substrate. A TFT 32 as a switching device and a pixel electrode 31 are 
provided for each of intersections of the plurality of gate bus lines and 
the plurality of drain bus lines. The TFT 32 is formed by a usual method 
including a plasma CVD method for deposition of an amorphous silicon 
(a-Si) film. As a result, the TFTs 32 are provided in a matrix manner on 
the glass substrate 19. 
A counter electrode substrate 26 is composed of a film substrate having the 
thickness of 0.1 mm. Polyether sulfone or polyethylene terephthalate is 
used as the material of the film substrate 26. The thickness of the film 
substrate 26 is preferably equal to or less than 0.6 mm, and more 
preferably equal to or less than 0.2 mm. A tablet electrode layer 27 of 
ITO is formed on the surface of the film substrate 26 opposing to the 
glass substrate 19. An insulating film 28 is formed on the whole surface 
including the tablet electrode layer 27 and then a counter electrode 29 of 
ITO is arranged on the insulating film 28 in corresponding to the pixel 
electrode 31. 
The TFT substrate 19 and the film substrate 26 are subjected to a rubbing 
process for orientation processing, after an orientating film such as 
polyimide is coated. Then, a spacer material is sprayed on one of the TFT 
substrate 19 and the film substrate 26 and a seal material is coated on an 
outer region other than a display region of the other. Thereafter, both of 
the TFT substrate 19 and the film substrate 26 are adhered each other to 
have a gap and then TN-type liquid crystal is poured into the gap between 
two substrates 19 and 26 so that a liquid crystal layer 30 is formed. The 
liquid crystal is driven by the counter electrode 29 and the pixel 
electrode 31 via the TFT 32. Thus, a liquid crystal panel is formed. 
The liquid crystal panel is sandwiched by a pair of polarizers 16 and 17. A 
backlight 6 is provided on the side of the polarizer 17 opposing to the 
TFT substrate 19. A driving circuit for driving the liquid crystal 30 and 
a detecting circuit for detecting a position or coordinate contacted by 
the input pen are omitted from the figure. The operation of the driving 
circuit is the same as in a conventional liquid crystal display apparatus. 
Also, the operation of the detecting circuit is the same as in the 
conventional tablet apparatus. For instance, the technique disclosed in 
Japanese Laid Open Patent Disclosure (JP-A-Heisei 4-195624) can be 
applied. 
In this manner, the tablet integrated type liquid crystal display apparatus 
is produced. In this case, the liquid crystal display apparatus is viewed 
from the side of the film substrate 26. 
An input pen 1 is used to input a data or instruction. A system using 
electrostatic capacitor coupling or electromagnetic induction between the 
input pen 1 and the tablet electrode layer 27 can be used for the pen 
input. For instance, an example of the electrostatic capacitor coupling 
system is described in U.S. Pat. No. 4,853,498 issued to Meadows et al. 
The description is incorporated herein by reference. It is desirable that 
another special pen input panel is not required in addition to the liquid 
crystal panel. However, if the film substrate 26 is used, a resistive film 
system may be applied to the tablet integrated type liquid crystal display 
apparatus, because the film substrate 26 is thin. 
As described above, because the film substrate 26 is made very thin, the 
parallax between the tip of the input pen 1 and a display image on the 
display panel can be almost eliminated. Further, because the TFT is 
produced on the thick TFT substrate 19 opposing to the film substrate 26 
which is located on the viewing side, the occurrence of bending of the 
substrate and damage of the TFT can be prevented. 
Next, a tablet-integrated-type liquid crystal display apparatus according 
to the second embodiment of the present invention will be described below. 
FIG. 5 is a cross sectional view illustrating the structure of the tablet 
integrated type liquid crystal display apparatus according to the second 
embodiment of the present invention. The liquid crystal display apparatus 
is a reflection type apparatus using an active matrix driving system. In 
the liquid crystal display apparatus, phase transit type guest host (GH) 
liquid crystal. 
The tablet integrated liquid crystal display apparatus in the second 
embodiment has the structure similar to that of the first embodiment. The 
insulating layer 28 of polyimide is coated onto the TFT 32 array and 
unevenness is formed on the insulating layer 28 by a usual photoresist 
process. The pixel electrode 31 is formed on the insulating layer 28. The 
pixel electrode 31 is connected to the corresponding TFT 32 via a contact 
hole. Because the pixel electrode 31 is also used as a reflection plate, 
the pixel electrode 31 is formed of metal such as aluminum (Al). Any 
polarizer is not required on either side of the liquid crystal display 
panel because the GH liquid crystal is used. Further, the backlight is not 
provided because the display panel is a reflection type. The other 
structural portions are the same as those of the first embodiment. 
As described above, in the tablet integrated type liquid crystal display 
apparatus in the second embodiment, because the pixel electrode 31 which 
is used as the reflection plate is provided in the liquid crystal panel, 
there is not a parallax between the reflection plate and the display image 
as in the conventional example. As a result, there is no case that the 
data or image is displayed in a floating state. Also, the parallax between 
the display image and the tip of the input pen 1 can be almost eliminated, 
as in the first embodiment. Further, the occurrence of bending of the TFT 
substrate 29 and damage of the elements can be prevented. 
In the first and second embodiment, the TFT is used as the switching 
element. However, the same effect can be obtained in the active matrix 
driving type, and tablet integrated type liquid crystal display apparatus 
using a 2-terminal element such as an MIM or TFD. This is applied to the 
following embodiments, too. 
Next, the tablet integrated type liquid crystal display apparatus according 
to the third embodiment of the present invention will be described. In the 
following description, an example in which the present invention is 
applied to a color liquid crystal display of 24 cm in a diagonal direction 
which has 640.times.480 RGB dots. 
FIG. 6 is a cross sectional view illustrating the structure of the tablet 
integrated type liquid crystal display apparatus in the third embodiment 
of the present invention. Referring to FIG. 6, a GH-type liquid crystal 5 
is sandwiched by a transparent TFT substrates 3 and a transparent counter 
electrode substrate 4 and is sealed between them. On a surface of the TFT 
substrate 3 opposing to the substrate 4, 480 scanning lines, 1920 signal 
lines, 921600 thin film field effect transistors (TFT) and pixel 
electrodes are formed. On the other hand, on a surface of the substrate 4 
opposing to the TFT substrate 3 with a color filter, counter electrodes of 
ITO are formed. Voltage is applied to the GH type liquid crystal 5 by the 
pixel electrode and the counter electrode via the TFT. The circuit 
structure of the tablet integrated type liquid crystal display apparatus 
in the third embodiment is shown in FIG. 7. The GH liquid crystal layer 5 
is connected to the corresponding TFT, the data driver and a common power 
supply in series. The gate of the TFT is connected to a gate driver. 
The operation principle to display an image in the third embodiment is the 
same as that of a conventional transmissive type active matrix driving 
type liquid crystal display apparatus. 
A tablet device 2 is provided on the other surface of counter electrode 
substrate 4. On a surface of a glass substrate (not illustrated) of the 
tablet apparatus 2, an ITO electrodes (not illustrated) are formed to 
detect a position on which an input pen 1 is put. A backlight 6 for the 
illumination is provided on the side of the other surface of the TFT 
substrate 3. 
On the other hand, input to the tablet device 2 is performed by making the 
input pen 1 contact the tablet device 2. For instance, two resistive films 
are made to contact with each other and the contact position is detected. 
In this case, the tablet device 2 and the counter electrode substrate 4 
are pushed because of pushing pressure so that the gap width between the 
TFT substrate 3 and the counter electrode substrate 4 changes. As a 
result, the thickness of the GH liquid crystal layer changes. However, 
because the transmissivity of the GH liquid crystal does not change so 
much, a problem in case of practical use does not occur. 
FIG. 8 is a graph illustrating the transmissivity change characteristics of 
the GH liquid crystal and the TN liquid crystal. In this graph, a solid 
line illustrates a simulation result of a transmissivity ratio between the 
case where a voltage is applied to the GH liquid crystal layer having the 
thickness of 5 .mu.m and the case where the same voltage is applied to the 
GH liquid crystal layer having the thickness of 4 .mu.m as the result of 
the pushing pressure. A dashed line illustrates a simulation result of a 
transmissivity ratio in the same cases. For instance, when the voltage of 
about 2 V is applied to the TN liquid crystal layer for a gray gradation, 
the display image changes greatly if the TN liquid crystal layer is 
changed from 5 .mu.m to 4 .mu.m in thickness. However, it could be seen 
that the display image does not change so much in the GH liquid crystal 
layer. The change in the transmissivity in the TN liquid crystal layer is 
twice in the GH liquid crystal layer. Further, the TN liquid crystal has 
contrast one order higher than the GH liquid crystal. Therefore, in the 
case of using the TN liquid crystal, the change of the display image in 
contrast before and after the liquid crystal panel is pushed is 
remarkable. However, in the tablet integrated type liquid crystal display 
panel using the GH liquid crystal, there is not such a problem in practice 
use. 
In the third embodiment, an example is described in which resistive films 
are contacted with each other. However, the tablet device is not limited 
to this. For instance, electrostatic capacitive coupling between the input 
pen 1 and the transparent ITO electrode may be used for detection of a 
coordinate in the tablet device 2. Alternatively, it is possible to apply 
to the tablet device the method which detects a coordinate using the 
electromagnetic coupling between the input pen 1 and the tablet device 2. 
In this case, the tablet device 2 is preferably provided rear the 
backlight 6. 
Next, the tablet integrated type liquid crystal display apparatus according 
to the fourth embodiment will be described below. In the following 
description, an example in which the present invention is applied to a 
color liquid crystal display of 24 cm in a diagonal direction which has 
640.times.480 RGB dots. 
FIG. 9 is a cross sectional view illustrating the structure of the tablet 
integrate type liquid crystal display apparatus in the fourth embodiment 
of the present invention. Referring to FIG. 9, a GH-type liquid crystal 5 
is sandwiched by a transparent TFT substrates 3 and a transparent counter 
electrode substrate 4 and is sealed between them. On a surface of the TFT 
substrate 3 opposing to the substrate 4, 480 scanning lines, 1920 signal 
lines, 921600 thin film field effect transistors (TFT) and pixel 
electrodes are formed. The pixel electrodes are connected to the 
corresponding to the TFTs. Reflection plates 7 of aluminum are provided 
above the pixel electrodes 7. On the other hand, on a surface of the 
substrate 4 opposing to the TFT substrate 3 with a color filter, counter 
electrodes of ITO are formed. Voltage is applied to the GH type liquid 
crystal 5 by the pixel electrode and the counter electrode via the TFT. 
A tablet device 2 is provided on the other surface of counter electrode 
substrate 4. On a surface of a glass substrate (not illustrated) of the 
tablet apparatus 2, an ITO electrodes (not illustrated) are formed to 
detect a position on which an input pen 1 is put. Because the liquid 
crystal display apparatus is a reflection type, any backlight 6 is not 
provided on the side of the other surface of the TFT substrate 3. 
The operation principle to display an image in the third embodiment is the 
same as that of a conventional transmissive type active matrix driving 
type liquid crystal display apparatus. 
On the other hand, input to the tablet device 2 is performed by making the 
input pen 1 contact the tablet device 2. In this case, the tablet device 2 
and the counter electrode substrate 4 are pushed because of pushing 
pressure so that the gap width between the TFT substrate 3 and the counter 
electrode substrate 4 changes. As a result, the thickness of the GH liquid 
crystal layer changes. However, because the transmissivity of the GH 
liquid crystal does not change so much, a problem in case of practical use 
does not occur, as described above. 
In the fourth embodiment, an example is described in which there may be 
used the method which detects a coordinate from the change of the 
resistance value when an electrode is pressed. However, the tablet device 
is not limited to this. Alternatively, electrostatic capacitive coupling 
between the input pen 1 and the transparent ITO electrode may be used for 
detection of a coordinate in the tablet device 2. Also, it is possible to 
apply to the tablet device the method which detects a coordinate using the 
electromagnetic coupling between the input pen 1 and the tablet device 2. 
In this case, the tablet device 2 is preferably provided rear the TFT 
substrate 3. 
Next, the tablet integrated type liquid crystal display apparatus according 
to the fifth embodiment of the present invention will be described. In the 
following description, an example in which the present invention is 
applied to a color liquid crystal display of 24 cm in a diagonal direction 
which has 640.times.480 RGB dots. 
FIG. 10 is a cross sectional view illustrating the structure of the tablet 
integrated type liquid crystal display apparatus in the fifth embodiment 
of the present invention. Referring to FIG. 10, a GH type liquid crystal 5 
is sandwiched by a transparent TFT substrates 3 and a transparent counter 
electrode substrate 4 and is sealed between them. On a surface of the TFT 
substrate 3 opposing to the substrate 4, 480 scanning lines, 1920 signal 
lines, 921600 thin film field effect transistors (TFT) and pixel 
electrodes are formed. On the other hand, on a surface of the substrate 4 
opposing to the TFT substrate 3 with a color filter, counter electrodes of 
ITO are formed. Voltage is applied to the GH type liquid crystal 5 by the 
pixel electrode and the counter electrode via the TFT. 
Tablet electrodes 8 of ITO are provided on the other surface of counter 
electrode substrate 4 to detect a position on which an input pen 1 is put. 
A protecting film 9 is provided on the tablet electrodes 8 to protect the 
tablet electrodes 8 from damage due to contact with the input pen 1. A 
backlight 6 for the illumination is provided on the side of the other 
surface of the TFT substrate 3. 
The operation principle to display an image in the third embodiment is the 
same as that of a conventional transmissive type active matrix driving 
type liquid crystal display apparatus. On the other hand, input to the 
tablet device 2 is performed by making the input pen 1 contact the tablet 
device 2. In this case, the tablet device 2 and the counter electrode 
substrate 4 are pushed because of pushing pressure so that the gap width 
between the TFT substrate 3 and the counter electrode substrate 4 changes. 
As a result, the thickness of the GH liquid crystal layer changes. 
However, because the transmissivity of the GH liquid crystal does not 
change so much, a problem in case of practical use does not occur, as 
described above. 
In the fifth embodiment, an example is described in which electrostatic 
capacitive coupling between the input pen 1 and the transparent ITO 
electrode is used for detection of a coordinate. However, the present 
invention is not limited to this, but there may be used the method which 
detects a coordinate from the change of the resistance value when an 
electrode is pressed. Also, the method may be used in which the potential 
of a tablet electrode 8 is detected by the input pen 1 to detect a 
coordinate. 
Next, the tablet integrated type liquid crystal display apparatus according 
to the sixth embodiment will be described below. In the following 
description, an example in which the present invention is applied to a 
color liquid crystal display of 24 cm in a diagonal direction which has 
640.times.480 RGB dots. 
FIG. 11 is a cross sectional view illustrating the structure of the tablet 
integrate type liquid crystal display apparatus in the sixth embodiment of 
the present invention. Referring to FIG. 11, a GH-type liquid crystal 5 is 
sandwiched by a transparent TFT substrates 3 and a transparent counter 
electrode substrate 4 and is sealed between them. On a surface of the TFT 
substrate 3 opposing to the substrate 4, 480 scanning lines, 1920 signal 
lines, 921600 thin film field effect transistors (TFT) and pixel 
electrodes are formed. The pixel electrodes are connected to the 
corresponding to the TFTs. Reflection plates 7 of aluminum are provided 
above the pixel electrodes 7. On the other hand, on a surface of the 
substrate 4 opposing to the TFT substrate 3 with a color filter, counter 
electrodes of ITO are formed. Voltage is applied to the GH type liquid 
crystal 5 by the pixel electrode and the counter electrode via the TFT. On 
the other surface of the counter electrode substrate 4, tablet electrodes 
8 of ITO are provided to detect a position on which an input pen 1 is put. 
A protection film 9 is provided to protect the tablet electrodes 8 from 
damage due to contact with the input pen 1. Because the liquid crystal 
display apparatus is a reflection type, any backlight 6 is not provided on 
the side of the other surface of the TFT substrate 3. 
The operation principle to display an image in the third embodiment is the 
same as that of a conventional transmissive type active matrix driving 
type liquid crystal display apparatus. 
On the other hand, input to the tablet device 2 is performed by making the 
input pen 1 contact the tablet device 2. In this case, the tablet device 2 
and the counter electrode substrate 4 are pushed because of pushing 
pressure so that the gap width between the TFT substrate 3 and the counter 
electrode substrate 4 changes. As a result, the thickness of the GH liquid 
crystal layer changes. However, because the transmissivity of the GH 
liquid crystal does not change so much, a problem in case of practical use 
does not occur, as described above. 
In the fourth embodiment, an example is described in which electrostatic 
capacitive coupling between the input pen 1 and the transparent ITO 
electrode is used for detection of a coordinate in the tablet device 2. 
However, the tablet device is not limited to this, but there may be used 
the method which detects a coordinate from the change of the resistance 
value when an electrode is pressed. Also, it is possible to apply to the 
tablet device the method which detects a coordinate using the 
electromagnetic coupling between the input pen 1 and the tablet device 2. 
In this case, the tablet device 2 is preferably provided rear the TFT 
substrate 3. 
Next, the tablet integrated type liquid crystal display apparatus according 
to the seventh embodiment will be described below. In the following 
description, an example in which the present invention is applied to a 
color liquid crystal display of 24 cm in a diagonal direction which has 
640.times.480 RGB dots. 
FIG. 12 is a cross sectional view illustrating the structure of the tablet 
integrate type liquid crystal display apparatus in the seventh embodiment 
of the present invention. Referring to FIG. 12, a GH-type liquid crystal 5 
is sandwiched by a transparent TFT substrates 3 and a transparent counter 
electrode substrate 4 and is sealed between them. On a surface of the TFT 
substrate 3 opposing to the substrate 4, tablet electrodes 10 are provided 
to use for detection of a coordinate pointed by the input pen 1. Above the 
tablet electrodes 10 via an insulating film (not shown), 480 scanning 
lines, 1920 signal lines, 921600 thin film field effect transistors (TFT) 
and pixel electrodes are formed. The pixel electrodes are connected to the 
corresponding to the TFTs. Reflection plates 7 of aluminum are provided 
above the pixel electrodes 7. On the other hand, on a surface of the 
substrate 4 opposing to the TFT substrate 3 with a color filter, counter 
electrodes of ITO are formed. Voltage is applied to the GH type liquid 
crystal 5 by the pixel electrode and the counter electrode via the TFT. On 
the other surface of the counter electrode substrate 4, a tablet device 2 
is provided to detect a position on which an input pen 1 is put. Because 
the liquid crystal display apparatus is a reflection type, any backlight 6 
is not provided on the side of the other surface of the TFT substrate 3. 
The operation principle to display an image in the third embodiment is the 
same as that of a conventional reflection type active matrix driving type 
liquid crystal display apparatus. 
On the other hand, input to the tablet device 2 is performed by making the 
input pen 1 contact the tablet device 2. In this case, the tablet device 2 
and the counter electrode substrate 4 are pushed because of pushing 
pressure so that the gap width between the TFT substrate 3 and the counter 
electrode substrate 4 changes. As a result, the thickness of the GH liquid 
crystal layer changes. However, because the transmissivity of the GH 
liquid crystal does not change so much, a problem in case of practical use 
does not occur, as described above. 
In the fourth embodiment, an example is described in which a coordinate is 
detected using the electromagnetic coupling between the input pen 1 and 
the tablet electrode 8. 
Next, the tablet integrated type liquid crystal display apparatus according 
to the eighth embodiment of the present invention will be described. In 
the following description, an example in which the present invention is 
applied to a color liquid crystal display of 24 cm in a diagonal direction 
which has 640.times.480 RGB dots. 
FIG. 13 is a cross sectional view illustrating the structure of the tablet 
integrated type liquid crystal display apparatus in the eighth embodiment 
of the present invention. Referring to FIG. 13, a GH-type liquid crystal 5 
is sandwiched by a transparent TFT substrates 3 and a transparent counter 
electrode substrate 4 and is sealed between them. On a surface of the TFT 
substrate 3 opposing to the substrate 4, 480 scanning lines, 1920 signal 
lines, 921600 thin film field effect transistors (TFT) and pixel 
electrodes are formed. On the other hand, on a surface of the substrate 4 
opposing to the TFT substrate 3 with a color filter, tablet electrodes 11 
are provided to detect a position on which an input pen 1 is put. Counter 
electrodes of ITO are formed above the tablet electrodes 11 via an 
insulating film. Voltage is applied to the GH type liquid crystal 5 by the 
pixel electrode and the counter electrode via the TFT. A backlight 6 for 
the illumination is provided on the side of the other surface of the TFT 
substrate 3. 
The operation principle to display an image in the third embodiment is the 
same as that of a conventional transmission type active matrix driving 
type liquid crystal display apparatus. On the other hand, the input pen 1 
is made to contact the counter electrode substrate 4. In this case, the 
counter electrode substrate 4 is pushed because of pushing pressure so 
that the gap width between the TFT substrate 3 and the counter electrode 
substrate 4 changes. As a result, the thickness of the GH liquid crystal 
layer changes. However, because the transmissivity of the GH liquid 
crystal does not change so much, a problem in case of practical use does 
not occur, as described above. 
In the eighth embodiment, an example is described in which electrostatic 
capacitive coupling between the input pen 1 and the transparent ITO 
electrode is used for detection of a coordinate. However, the present 
invention is not limited to this, but the method may be used in which the 
potential of a tablet electrode 8 is detected by the input pen 1 to detect 
a coordinate. 
Next, the tablet integrated type liquid crystal display apparatus according 
to the ninth embodiment of the present invention will be described. In the 
following description, an example in which the present invention is 
applied to a color liquid crystal display of 24 cm in a diagonal direction 
which has 640.times.480 RGB dots. 
FIG. 14 is a cross sectional view illustrating the structure of the tablet 
integrated type liquid crystal display apparatus in the ninth embodiment 
of the present invention. Referring to FIG. 14, a TN-type liquid crystal 
24 is sandwiched by a transparent TFT substrates 3 and a transparent 
counter electrode substrate 4 and is sealed between them. On a surface of 
the TFT substrate 3 opposing to the substrate 4, 480 scanning lines, 1920 
signal lines, 921600 thin film field effect transistors (TFT) and pixel 
electrodes are formed. On the other hand, on a surface of the substrate 4 
opposing to the TFT substrate 3 with a color filter, counter electrodes of 
ITO are formed. Voltage is applied to the TN type liquid crystal 5 by the 
pixel electrode and the counter electrode via the TFT. 
A tablet device 2 is provided on the other surface of the counter electrode 
substrate 4. A backlight 6 for the illumination is provided on the side of 
the other surface of the TFT substrate 3. 
After the TFT substrate 3 is formed by the same method as in the 
conventional technique, a polyimide film is formed on it. The polyimide 
film is patterned into a plurality of rectangular shapes by a 
photo-lithography method so that a plurality of supports 25 are formed. 
The supports 25 are provided to avoid the pixel electrodes with the period 
as much as the pixel pitch. 
The operation principle in the present embodiment for displaying an image 
is same as the case of the active matrix-type liquid crystal display 
apparatus of the conventional transmission type. On the other hand, input 
to the tablet device 2 is performed using the input pen 2. At this time, 
the tablet device 2 and the counter electrode substrate 4 are pushed 
because of pushing pressure. However, because the supports 25 are inserted 
between the counter electrode substrate 4 and the TFT substrate 3 with the 
very short period, the gap width of TN-type liquid crystal layer 24 
changes hardly. Even if the change occurs, the change is within one pixel 
because the supports 25 are provided with the period as long as the pixel 
period. Therefore, a problem does not occur in case of practical use. 
In the above example, the supports 25 which connect the counter electrode 
substrate 3 and the TFT substrate 4 are formed of the polyimide film by 
the photo-lithography method. However, the present invention is not 
limited to this. Other means may be used if a material and structure are 
selected such that the gap width of the liquid crystal layer is not 
changed because of the pushing pressure so that the display image is not 
degraded. 
In the present embodiment, the case that the supports are rectangular was 
described. However, the shape of the support may be different if there is 
no problem in the pouring and orientation of liquid crystal. Further, it 
was described that the supports 25 are arranged with the period as long as 
the pixel pitch. However, if the change of the gap width of the liquid 
crystal layer is so small that the degradation of a display image is not 
sensitive to a user, the period may be extended or shortened. 
Alternatively, the supports 25 may be arranged randomly. 
As described above, according to the present invention, because a 
protection board is not necessary which is inserted between the liquid 
crystal display and the tablet not to change the gap width of the liquid 
crystal layer, the weight of the tablet integrated type liquid crystal 
display apparatus can be reduced 20%. 
Also, the thickness of the display apparatus can be reduced to about half 
of that of the conventional display apparatus. Further, because the thick 
protection board is not inserted between the tip and the display 
apparatus, it is possible to realize the display apparatus with no 
parallax. 
Also, according to the present invention, the glass substrate is used for 
the TFT substrate and the plastic film substrate having the thickness 
equal to or less than 0.6 mm is used for the counter electrode substrate. 
In addition, the counter electrode substrate is arranged on the viewing 
side. Therefore, the parallax between the display image and the tip of the 
input pen input can be almost eliminated. Further, the occurrence of 
bending of the TFT substrate and damage of the elements such as the TFTs 
can be prevented. 
If the present invention is applied to the personal computer display having 
480.times.640 RGB dots, a tablet integrated type liquid crystal display 
apparatus can be achieved to have the resolution of about 200 .mu.m and to 
reduce the weight and the thickness.