Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-03-24
2003-02-04
Chang, Kent (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S100000, C345S096000
Reexamination Certificate
active
06515647
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a matrix display apparatus. The present invention is effective for using matrix displays, such as liquid-crystal device (LCD) panels, as High-Vision resolution display devices.
BACKGROUND OF THE INVENTION
It is expected that new television systems, such as digital satellite broadcast systems and digital terrestrial broadcast systems will take place of the conventional NTSC and MUSE systems in near future across the 21st century.
In the NTSC system, a 480 lines interlaced scanning system has been adopted. In the Hi-Vision broadcast systems adopting the MUSE system, a total of 1125 scan lines are used, while 1035 scan lines present on an actually-visible display screen. Therefore, conventional monitors and television (TV) receivers were enough to be compatible to a total of 1125 scan lines and the actually-visible 1035 scan lines.
Incidentally, in plans of digital broadcasts, such as the DTV system decided in the United States and similar systems on diagram boards in the world, a variety of scanning systems are proposed. For example, a 480 lines interlaced scanning system (hereinafter referred to 480i), a 480 lines progressive scanning system (hereinafter referred to 480p), a 1080 lines interlaced scanning system (hereinafter referred to 1080i) and a 720 lines progressive scanning system (hereinafter referred to 720p) have been planned.
Therefore, it is needed that the monitors and the TV receivers is compatible to not only the conventional NTSC and MUSE system broadcasts, but also to a variety of scanning systems.
Referring now to
FIG. 12
, a construction of conventional TV receivers will be described.
In
FIG. 12
a DTV (digital television) demodulator
11
demodulates digital color TV signals from an OFDM (Orthogonal Frequency Division Multiplexing)-modulation digital color TV broadcast signal received through an antenna, such as a parabola antenna. A DTV decoder
12
decodes MPEG-2 encoded signals from the DTV demodulator
11
. An analog-to-digital (A/D) converter
13
converts analog signals of 1080i scan format, or analog signals of 1035i scan format into 10-bit order digital signals. Here, color TV signals definitely consist of three-color signals, i.e., a luminance signal (Y) and two color-difference signals (Pr, Pb). Thus the A/D converter
13
is actually comprised of three units (not shown). A 1080i/720p converter
14
converts 1080i scan format signals to 720p scan format signals by alternatively storing the odd and even fields each consisting of 540 scan lines into a frame memory, and applying a motion-adaptive processing etc.
In this embodiment, although an exemplified conversion from mainly a 1080i format to a 720p format is described, the same goes for a conversion from a 1035i format to the 720p format. By the way, the conventional Hi-Vision system signal also utilizes a total number of 1125 lines the same as that of the digital TV system signal. Thus, by processing 45 lines of them as lines in a non-image area, i.e., a vertical retrace period, the same circuit configuration and operation can be applied to both of the Hi-Vision system and the digital TV system.
An analog-to-digital converter (A/D converter)
15
converts the 480i scan format or the 480p scan format from analog form to digital form. A 480i(p)/720p converter
16
converts the digital signals from the A/D converter
15
from a 480i(p) scan format to a 720p scan format. Wherein, 480i scan format signals are converted into 720p scan format signal while storing odd and even fields each consisting of 240 scan lines into a field memory and performing a motion-adaptive signal processing. On the other hand, 480p scan format signals are converted into the 720p scan format signals in every fields.
A selector
17
selects either the digital signals from the 1080i/720p converter
14
or the 480i(p)/720p converter
16
. A D/A converter
18
converts the image signals selected by the selector
17
from digital form back to analog form. Since color displays require three signals, i.e., a luminance signal (Y signal) and two color-difference signals (Pr, Pb), the D/A converter
18
is actually comprised of three units (not shown).
An LCD driver
19
adequately processes the luminance signal Y and the color-difference signals Pr, Pb to drive an LCD panel
21
. The LCD driver
19
comprises a matrix circuit for restoring three primary color signals R, G, B from the luminance signal Y and the color-difference signals Pr, Pb, a gamma correction circuit for correcting voltage-luminance characteristics curve of the LCD panel
21
, a polarity alternator for alternating polarities of signals given to the LCD panel
21
. Here, the alternate-driving of LCDs is performed for preventing deteriorations of LCDs caused by applying only one polarity signal to LCD panels.
An LCD controller
20
controls timings of enabling scan lines (rows) y
1
, y
2
, y
3
, . . . and data lines (columns) x
1
, x
2
, x
3
, . . . of the LCD panel
21
in synchronism with the drive signals supplied from the LCD driver
19
. When the LCD panel
21
is of a low-cost and of a midrange resolution, 720 units of scan lines (rows) y
1
, y
2
, y
3
, . . . are vertically aligned, while 1280 units of data-lines (columns) x
1
, x
2
, x
3
, . . . are laterally aligned.
The LCD controller
20
deals with three drive signals associated to the luminance signal Y and the color-difference signals Pr, Pb. Thus the LCD controller
20
is actually comprised of three units (not shown). In the receiver, as shown in
FIG. 12
the LCD panel
21
accepts three types of drive signals. The first drive signal originates from the 1080i scan format signal which is obtained by demodulating the DTV-modulation transmitting signal in the DTV demodulator
11
and then decoded in the DTV decoder
12
. The second drive signal originates from the analog luminance signal and color-difference signals of the 1080i or the 1035i scan format which are supplied from conventional MUSE decoders or MUSE disc players to the A/D converter
13
. The 1080i format signals associated to the first and the second drive signals are converted into the 720p scan format signal in the 1080i/720p converter
14
. The third drive signal originates from the 480i or the 480p scan format signals such as the conventional NTSC signals supplied to the A/D converter
15
and then converted to the 720p scan format signal in the 480i(p)/720p converter
16
.
Since all of the above-mentioned three drive signals are converted their formats into the 720p scan format before the LCD panel
21
, if their scanning line signals are supplied one by one into the LCD panel
21
in their order, a correct image corresponding to the scan format conversion algorism is displayed on the LCD panel
21
.
Although the A/D converter
13
can convert analog 1080i or 1035i scan format signals into 8-bit or 10-bit digital signals, it requires a very high sampling frequency of 75 MHz and also three units of expensive converters for the luminance signal Y and the color-difference signals Pr and Pb, respectively. Moreover, since separate type MUSE decoders and disc players are not presently in common, input terminals for the MUSE decoders and disc players are rarely used. Nevertheless, an equipment of three expensive A/D converters and their peripheral devices has caused the burden on great cost. If their costs could be suppressed sufficiently close to a price reasonable for customers, such an attempt of reducing costs can contribute for a proliferation of monitors and TV receivers compatible not only to the conventional NTSC and MUSE system broadcasts, but also to a variety of scanning systems.
SUMMARY OF THE INVENTION
With consideration for the above problems, the object of the present invention is to provide a matrix display apparatus to which analog signals can be directly supplied thus eliminating the need for expensive A/D and/or D/A converters, by devising driving schemes of the LCD panels.
To achieve the above objects, a matrix display apparatus according to a first aspect of the pre
Chang Kent
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
Sheng Tom V.
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