Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-06-05
2003-06-24
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S209000
Reexamination Certificate
active
06583778
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for driving a matrix type LCD (liquid crystal displaying) apparatus composed of a plurality of pixels arranged in rows and columns.
Generally the matrix type LCD apparatus is composed of a plurality of pixels. The plurality of pixels are arranged in rows and columns with a plurality of first lines arranged parallel to each other and a plurality of second lines perpendicular to the first lines provided as boundary lines. Thin film transistors (hereinafter referred to as TFTs) are provided as active elements in the crossing portions between the first lines and the second lines. The pixels include liquid crystals.
One example of a method of driving the conventional LCD apparatus will be described.
FIGS.
20
(
a
) and
20
(
b
) are illustrating diagrams each showing one example of the conventional LCD apparatus. FIG.
20
(
a
) shows polarities of the column signals (or the image signals) to be applied to pixels of the LCD apparatus in a certain frame (for example, m frame, where m is 0 (zero) or natural number). FIG.
20
(
b
) shows polarities of column signals to be applied to pixels of the LCD apparatus in (m+1) frame. In FIGS.
20
(
a
) and
20
(
b
), reference numeral
1
denotes a signal driving circuit for generating column signals to be applied to pixels, reference numeral
2
denotes a row driving circuit for generating row signals (or line signals) for selecting the rows, reference numeral
3
shows first lines, lines (hereinafter referred to as “column signal line”) connected with the signal driving circuit
1
for generating the column signals, reference numeral
4
denotes second lines, lines (hereinafter referred to as “row signal line”) connected with the row driving circuit
2
for generating the row signals, reference numeral
5
shows pixels. A “+” or “−” shown to the pixels indicates a polarity, that is, positive or negative, as a model, of the column signal to be applied upon the pixel.
In FIGS.
20
(
a
) and
20
(
b
), number of the column signal lines
3
is 14, number of the row signal lines
4
is 12, and number of the pixels is 168, but the respective number of the column signal lines
3
, the row signal lines
4
and the pixels is not restricted to the above description TFTs are provided in the crossing portions between the column signal lines
3
and the row signal lines
4
, and the TFTs are connected with the column signal lines
3
and the row signal lines
4
, which are not shown in FIGS.
20
(
a
) and
20
(
b
). When a row signal having a voltage value, which turns on the TFT only in the particular row signal line, of a plurality of row signal lines
4
, is applied (namely, a specific row signal line is selected), the TFT connected with the specific row signal line is turned on, and the remaining TFTs are turned off. A column signal generated by a signal driving circuit is applied to only pixels including the turned on TFT.
In order to display a given image, the LCD apparatus carries out operations of,
(1) giving to column signal lines
3
a plurality of column signals outputted from the signal driving circuit
1
,
(2) selecting a specific row signal line
4
by a row signal outputted from the row driving circuit
2
,
(3) turning on only a TFT connected with the selected row signal line
4
,
(4) applying a given column signal generated by the column driving circuit to each pixel including the turned on TFT, and
(5) controlling a transmission factor of the liquid crystal light of each pixel by the potential difference between the applied predetermined column signal and the opposite common signal. The column signal and the opposite signal are applied to two electrodes (not shown) which give an electric field to the liquid crystal.
When the voltage of the same polarity is generally applied to the liquid crystal for long hours, the liquid crystal is often deteriorated. In case the voltage stops applying to the liquid crystal, the transmission factor of the liquid crystal light may be returned to the light transmission factor before the voltage is applied to the liquid crystal. Thus, it is necessary to alternate the column signal by often changing the polarity of the column signal to be applied. In the conventional LCD apparatus shown in FIGS.
20
(
a
) and (
b
), the polarity of the column signal to be applied to each pixel is changed for each frame to drive the LCD apparatus. A method of driving the LCD apparatus by changing the polarity of the column signal for each frame is a frame inversion driving method. When the frame inversion driving method is used, a period where the polarity of the column signal changes becomes a low frequency. In the actual displaying operation, flickers (in image) on the display are conspicuous. Since the column signal is the same in polarity as the row signal in one frame, cross talk becomes larger by receiving the influences of the column signal and the row signal to be applied on the other pixels, thereby deteriorating the picture quality.
A method of driving the conventional LCD apparatus provided for solving the above described problems.
FIG. 21
is illustrating diagram showing the other examples of the conventional LCD apparatus. In
FIG. 21
, the same reference numerals are used about the same locations as those of FIGS.
20
(
a
) and
20
(
b
). In the LCD apparatus shown in
FIG. 21
, the polarity of the column signal is changed for each pixel to drive the LCD apparatus. A method of changing the plurality of the column signal for each pixel to drive the LCD apparatus is referred to as dot inversion driving method. When the dot inversion driving method is used, flickers and cross talk which are caused by using the frame inversion driving method are reduced. A period where the plurality of the column signal becomes an extra-high frequency to increase the power consumption in driving the LCD apparatus. The number of the pixels increases due to recent higher resolution, and time for applying the column signal upon pixels becomes shorter, thereby causing faulty charging to lower the picture quality.
When the frame inversion driving method is used, flickers and cross talk are caused to lower the picture quality. When the dot inversion driving method is used, power consumption in driving the LCD apparatus increases. In the LCD apparatus of high resolution, inferior charging is caused to lower the picture quality. Thus, it is hard to make the high picture quality and the lower power consumption compatible.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a method of driving a LCD apparatus of realizing the high picture quality by reducing the flickers, and of lower power consmuption.
A method of driving an LCD apparatus according to the present invention is to display the predetermined images by applying the predetermined column signals upon the pixels for constituting the selected rows, of a plurality of pixels arranged in rows and columns, where a plurality of pixels are divided into a plurality of groups each composed of at least two pixels in the column direction, so as to change the polarity of the column signal for each group.
In the present specification, the column direction is referred to as a direction parallel to the column signal line.
A method of driving the LCD apparatus according to the present invention is to change for each frame the pixels constituting each group.
In a method of driving the LCD apparatus described in the present invention, one group is composed of n pixels and the boundary portion between the groups is shifted by (n−1) pixels for each frame.
A method of driving the LCD apparatus according to the present invention is to change for each group the number of the pixels for constituting one group.
A method of driving the LCD apparatus described in the present invention is to change regularly the number of the pixels for constituting the one group.
A method of driving the LCD apparatus described in the present invention is to change irregularly the number of the pixel
Kohno Yasuhiko
Nishimura Masaru
Dinh Duc
Hjerpe Richard
Mitsubishi Denki & Kabushiki Kaisha
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