Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-05-27
2002-10-22
Shankar, Vijay (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S100000
Reexamination Certificate
active
06469686
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to display apparatus and display method for performing displaying of an image using picture elements or “pixels” as disposed in a matrix fashion. In particular, the invention relates to a liquid crystal display device and EL display device of the active matrix type.
2. Description of the Related Art
Recently, the technology has been rapidly developed for fabrication of semiconductor devices with a semiconductor thin film being formed on a glass substrate of low cost, such as for example thin-film transistors (TFTs). The reason for this is that the needs for liquid crystal display devices of the active matrix type are increasing more and more.
The active-matrix type liquid crystal display device is such that TFTs are disposed respectively in several tens or several millions of pixel regions that are disposed in a matrix manner, which TFTs have their switching functions to control electrical charge carriers exiting from or entering to a respective one of pixel electrodes.
FIG. 1
shows a configuration of a liquid crystal display device of the active matrix type in the prior art. A shift register and buffer circuitry are typically called the “peripheral driver circuit” in general; in the recent years, this is integrally formed on the same substrate together with an active matrix circuit.
Disposed in the active matrix circuit are thin-film transistors which utilize amorphous silicon as formed on a glass substrate used.
A configuration has also been known wherein quartz is utilized as the substrate while employing a polycrystalline silicon film for fabrication of such thin-film transistors. In this case both the peripheral driver circuit and active matrix circuit will be constituted from those thin-film transistors formed on the quartz substrate.
In addition, a thin-film transistor fabrication technology is also known which makes use of a crystalline silicon film on a glass substrate by utilizing laser anneal techniques or the like. Use of this technology may enable integration of the active matrix circuit and its associated peripheral driver circuit on the glass substrate.
In the configuration shown in
FIG. 1A
, an image signal being supplied to an image signal line is selected at a timing as indicated by
FIG. 1B
in response to a signal from a shift register circuit (horizontal scanning shift register) of a source line side driver circuit. And, certain image signal will be supplied to a corresponding source signal line.
The image signal which was supplied to the source signal line is then selected by the thin-film transistor of a pixel to be written into a specified pixel electrode.
The pixel thin-film transistor is operable in response to a selection signal that is supplied via a gate signal line from a shift register (vertical scanning shift register) of a gate line side driver circuit not shown herein.
The above operation will be recurrently carried out with the setting of appropriate timings determinable depending on a signal from the shift register of the source line side driver circuit and a signal from the shift register of the gate line side driver circuit to thereby sequentially write information into respective pixels of the matrix shape.
After completion of writing of image information corresponding to a single screen, image information is then written for the next screen. In this way, displaying of images will be performed in a sequential order. Generally, such writing of this one-screen information is repeated for thirty times or alternatively sixty times per second.
SUMMARY OF THE INVENTION
In recent years, as the information amount increases rapidly, an attempt has been made to attain an increase in display capacity as well as an increase in precision of display image resolution. Here, some major examples of the display resolution standards as generally employable in computers will be indicated along with pixel numbers and standard titles.
Pixel Number (Width × Height)
: Name of Standard
640 × 400
: EGA
640 × 480
: VGA
800 × 600
: SVGA
1024 × 768
: XGA
1280 × 1024
: SXGA
Today, even in the field of personal computers, software program packages have become widely available which perform a plurality of display operations different in nature from one another on the display screen; accordingly, a shift has been made to those display devices which are higher in display resolution than VGA and SVGA standards to accommodate the XGA and SXGA standards.
Furthermore, the prescribed liquid crystal display devices of high display resolution have also been employed for use in displaying television broadcast signals other than displaying of data signals in such personal computers.
As is well known, the currently available television signals may generally be classified into several groups which are based on the NTSC scheme, PAL scheme, and SECAM scheme. The NTSC television scheme has the degree of image resolution which is 525 in scanning-line number (effective scan line number is approximately 480). The PAL and SECAM schemes are 625 in scan line number (effective scan line number is 576).
In cases where an image based on television signals of the NTSC scheme or PAL scheme or alternatively SECAM scheme is to be visually indicated on a liquid crystal display device that accommodates the SVGA or XGA or SXGA standard stated supra, it will be required that an image non-display section (image-absent area on the screen) be provided due to a difference in resolution among them.
Now refer to
FIGS. 2A and 2B
.
FIGS. 2A and 2B
are schematical diagrams of liquid crystal display devices of the peripheral driver circuit integration type that are designed to accommodate the XGA standard. In
FIG. 2A
, reference numeral
201
is a source side driver circuit.
202
is a gate line side driver circuit.
203
is a TFT active matrix circuit section. In
FIG. 2B
numeral
207
is a sourceside driver circuit.
208
is a gate line side driver circuit.
209
is a TFT active matrix circuit section.
In the case of displaying an image based on a television signal of the PAL scheme on the liquid crystal display device accommodating the XGA standard, an image display section
204
and image non-display sections
205
and
206
are required as shown in FIG.
2
A.
Alternatively, in the case of displaying an image based on a television signal of the NTSC system on the liquid crystal display device accommodating the XGA standard, a display section
210
and its surrounding image non-display section
211
are required as shown in FIG.
2
B.
It will be desirable that the image non-display sections
205
,
206
and
211
be designed to display the complete black color in order to maximally enhance a visual difference from the image display sections
204
and
210
.
In the related art an attempt has been made to let the image non-display sections be colored in block in the way described above. However, the related art approach was difficult in achievement of such completely black-colored display in the image non-display sections. As a result, a decrease in quality has taken place.
As another method for displaying an image represented by a television signal on a liquid crystal display device that accommodates the XGA standard, a method is known which is for inputting the television signal to the driver circuit of the liquid crystal display device after acquiring or “downloading” to an associative personal computer and then converting and processing to a specific signal that corresponds in format to the XGA standard. In this case a separate device or circuit should additionally be required for conversion and processing of the television signal. Further, signal attenuation or degradation can occur due to the fact that the television signal must pass through such extra device or circuit, which would result in a decrease in image quality.
In accordance with one preferred practicing form of the present invention, a display device is provided which at least includes a plurality of TFTs, a sign
Koyama Jun
Shionoiri Yutaka
Robinson Eric J.
Robinson Intellectual Property Law Office PC
Semiconductor Energy Laboratory Co,. Ltd.
Shankar Vijay
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