Computer graphics processing and selective visual display system – Display driving control circuitry – Physically integral with display elements
Reexamination Certificate
1997-09-25
2002-05-07
Cuchlinski, Jr., William A. (Department: 3661)
Computer graphics processing and selective visual display system
Display driving control circuitry
Physically integral with display elements
C349S151000
Reexamination Certificate
active
06384818
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrooptical device having driver circuits consisting of semiconductor devices making use of thin-film semiconductors and also to a method of fabricating such an electrooptical device. More particularly, the invention relates to an active matrix electrooptical device (AMEOD) where a pixel matrix circuit and logic circuitry are integrated on the same panel.
2. Description of the Related Art
In recent years, techniques for fabricating thin-film transistors (TFTs) on an inexpensive substrate have evolved rapidly, because there is an increasing demand for active matrix electrooptical devices. In an active matrix electrooptical device, millions of pixels are arranged in rows and columns. TFTs are arranged at each pixel. Electric charge going into and out of each pixel electrode is controlled by the switching action of each TFT.
Electrooptical devices include liquid crystal displays making use of optical characteristics of liquid crystals, electroluminescent displays employing electroluminescent materials typified by ZnS:Mn, and electrochromic displays exploiting the color changing characteristics of electrochromic materials.
These electrooptical devices are active devices that can be matrix-addressed. High-definition display can be accomplished by utilizing this active matrix construction. As mentioned above, a great feature of the active matrix construction lies in that electric charge going into and out of pixel electrodes arranged in rows and columns within an image display region of an electrooptical device is controlled by turning on and off pixel electrodes disposed at the pixels.
Another feature of the active matrix construction is that driver circuits for driving pixel TFTs are necessary to control pixels. In the prior art technique, a pixel matrix circuit formed on a glass substrate has been connected with a separately prepared driver IC to form an active matrix circuit.
In recent years, however, it has become common practice to form plural circuit TFTs forming driver circuits and a pixel matrix circuit on the same substrate to build driver circuits (known as peripheral driver circuits) around the pixel matrix circuit.
More recently, a system-on-panel (SOP) structure has attracted attention comprising a substrate on which control circuits (e.g., a processor circuit, memory circuits, A/D or D/A converter circuits, correcting circuits, and a pulse-generating circuit) are formed, as well as driver circuits (such as shift register circuits or buffer circuits) for driving pixel TFTs.
A general construction of an electrooptical device is shown in
FIG. 3
, which gives an example of active matrix liquid crystal display. A pixel matrix circuit
302
is formed on a glass substrate
301
. This pixel matrix circuit
302
consists of integrated pixel regions. A portion of the pixel matrix circuit
302
is shown on an expanded scale at
303
, where plural regions (two regions in this example) are arranged in rows and columns. At least one pair of pixel TFT/pixel electrode is disposed in each pixel region.
A horizontal scanning driver circuit
304
for transmitting data signals to data lines comprises shift register circuits, level-shifting circuits, buffer circuits, and sampling circuits. The level-shifting circuits amplify driving voltages.
It is assumed that a shift register circuit is operated with 10 and that a buffer circuit is operated with 16. In this case, it is necessary to convert the voltages into other values by a level-shifting circuit. Sometimes, a shift register circuit may be constructed by combining a counter circuit with a decoder circuit. A vertical scanning driver circuit
305
for transmitting gate signals to gate lines comprises a shift register circuit, a level-shifting circuit, and a buffer circuit.
It is expected that a control circuit
306
will be located in the position shown in
FIG. 3
in near future. Since the control circuit
306
is composed of complex logic circuitry or memory circuitry such as a processor occupying a large area, it is expected that the total area occupied will increase.
As described above, the pixel matrix circuit
302
, the horizontal scanning driver circuit
304
, the vertical scanning driver circuit
305
, and the control circuit
306
are generally disposed on one glass substrate
301
. Accordingly, in order to secure a maximum display area on a given size of glass, it is necessary to minimize the area occupied by circuits other than the pixel matrix circuit.
However, even if the marginal structure as shown in
FIG. 3
is adopted, limitations are imposed on increases of the device density of the peripheral driver circuits. Where other values or advantages are added like a control circuit, it is more difficult to increase the area of the pixel matrix circuit.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electrooptical device, or an optical display device, in which a pixel matrix circuit providing display regions is maximized in area by solving the foregoing problems to thereby accomplish a large area display making full use of the size of the substrate.
An electrooptical device in accordance with the present invention comprises a pixel matrix circuit and logic circuitry formed on the same substrate. The pixel matrix circuit occupies regions in which the logic circuitry is fully or partially disposed.
The present invention also provides an electrooptical device comprising an active matrix substrate having a pixel matrix circuit and logic circuitry thereon. A liquid crystal material layer is held on the active matrix substrate. The pixel matrix circuit occupies regions in which the logic circuitry is fully or partially disposed.
A gist of the present invention lies in an electrooptical device operating in the reflective mode or in the emissive mode. This device is characterized in that pixel regions located on the rear side of the pixel electrodes are effectively utilized. That is, the logic circuitry which would have heretofore been disposed in an outside frame of the pixel matrix circuit as shown in
FIG. 3
is totally or partially built into the pixel matrix circuit, by making use of the pixel regions.
A cross section is taken through the active matrix construction on which the pixel matrix circuit is integrated with the logic circuitry. In this cross section, the logic circuitry is fully or partially located below the pixel electrodes connected with the pixel TFTs forming the pixel matrix circuit.
The logic circuitry means circuits other than the pixel matrix circuit consisting of driver circuits and/or control circuits. The control circuits embrace every information-processing circuit necessary to drive an electrooptical device, and are typified by processor circuit, memory circuit, A/D or D/A converter circuit, correcting circuit, a pulse-generating circuit.
Since an electrooptical device operated in the reflective mode (typically, a reflective-type liquid crystal display) does not need to transmit light, it is not necessary to make the pixel electrodes transparent to secure optical paths, unlike the transmissive-type liquid crystal display. Therefore, the rear side of the pixel electrodes (the lower side in the cross section described above) which has been heretofore impossible for the transmissive-type liquid crystal display to utilize can be effectively exploited to dispose the logic circuitry.
The reflective-type liquid crystal display operating in the aforementioned reflective mode is next described briefly by referring to FIGS.
4
(A) and
4
(B). Shown in FIG.
4
(A) are an active matrix substrate
401
, a counter substrate
402
, and a liquid crystal material layer
403
. Pixel electrodes
404
are formed on top of the active matrix substrate
401
. If necessary, a reflecting plate may be formed. The pixel electrodes
404
are protected by a protective film
405
.
FIG.
4
(A) shows the state in which a TFT is OFF. That is, liquid crystal molecules are oriented in such a way that they do not vary
Fukunaga Takeshi
Koyama Jun
Yamazaki Shunpei
Fish & Richardson P.C.
Nguyen Thu
Semiconductor Energy Laboratory Co,. Ltd.
LandOfFree
Electrooptical device and method of fabricating the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrooptical device and method of fabricating the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrooptical device and method of fabricating the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2869708