Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-08-13
2004-03-16
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S096000
Reexamination Certificate
active
06707442
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to driving apparatus and driving method of liquid crystal display apparatus that is provided with a differential amplifier which outputs offset voltages, having positive and negative polarities whose amplitudes are equal to each other, that are happened to be generated due to the characteristic unevenness occurred by the manufacturing process.
BACKGROUND OF THE INVENTION
FIG. 6
is a block diagram showing a typical liquid crystal display apparatus, having TFTs, of active matrix type.
3801
shows a TFT liquid crystal panel,
3802
shows a source driver IC having a plurality of source drivers,
3803
shows a gate driver IC having a plurality of gate drivers,
3804
shows a control circuit, and
3805
shows a liquid crystal driving power source (a power source circuit).
The control circuit
3804
sends a vertical synchronizing signal to the gate driver IC
3803
, and sends a horizontal synchronizing signal to the source driver IC
3802
and the gate driver IC
3803
, respectively. Display data (respective display data that are separated to R, G, and B) that have been externally applied are sent to the source driver IC
3802
in a form of digital signal via the control circuit
3804
. In the source driver IC
3802
, the display data that have been inputted are latched in a time sharing manner, and then, are subjected to digital to analog conversion in synchronization with the horizontal synchronizing signal outputted from the control circuit
3804
so as to output an analog voltage for the gradation display via a liquid crystal driving output terminal.
FIG. 42
is a structural diagram of the TFT liquid crystal panel.
3901
shows a pixel electrode,
3902
shows a pixel capacity,
3903
shows a TFT switch (switching device),
3904
shows a source signal line,
3905
shows a gate signal line, and
3906
shows an opposite electrode.
To the source signal line
3904
a gradation display voltage that varies depending on the brightness of the display pixel is applied from the source driver IC
3802
. To the gate signal lines
3905
scanning signals are applied from the gate driver IC
3803
so that the TFTs that are provided in a longitudinal direction are successively turned on. Voltages on the respective source signal lines
3904
are applied to the pixel electrodes
3901
that are connected with drains of the respective TFTs
3903
via the TFTs
3903
that are turned on. This causes the pixel capacity
3902
is formed between the pixel electrodes
3901
and the opposite electrode
3906
, thereby resulting in that the light transmittance of the liquid crystal changes so as to carry out the display in accordance with the change in the light transmittance.
FIGS. 12 and 13
exemplify how the wave form of the liquid crystal driving voltage changes.
4001
and
4101
show wave forms of the driving voltages outputted from the source driver, respectively.
4002
and
4102
show wave forms of the driving voltages outputted from the gate driver, respectively.
4003
and
4103
show voltages (electric potentials) of the opposite electrodes.
4004
and
4104
show a voltage wave form of the pixel electrode.
The voltage (see the oblique lines in
FIGS. 12 and 13
) which is applied to the liquid crystal material is equal to the voltage difference between the pixel electrode
3901
and the opposite electrode
3906
. It is necessary that the liquid crystal panel is driven by an alternating current voltage.
FIG. 12
shows the following case. More specifically, when the output voltage of the source driver is greater than the voltage of the opposite electrode, the TFT
3903
is turned on in response to the output signal of the gate driver. A voltage showing a positive polarity with respect to the opposite electrode
3906
is applied to the pixel electrode
3901
. Then, the TFT
3903
is turned off, so that such a voltage is maintained.
In contrast,
FIG. 13
shows the following case More specifically, when the output voltage of the source driver is smaller than the voltage of the opposite electrode
3903
, the TFT
3903
is turned on in response to the output signal of the gate driver. A voltage showing a negative polarity with respect to the opposite electrode
3906
is applied to the pixel electrode
3901
. Then, the TFT
3903
is turned off, so that such a voltage is maintained. Thus, when the wave form voltages of
FIGS. 12 and 13
are alternately applied, it is possible that the liquid crystal material is driven by the applied voltage that is an alternating voltage.
FIG. 14
exemplifies the polarity arrangement, on the liquid crystal panel
3801
, for the alternating of the driving voltage. This is called as a dot reverse driving. According to this type of driving, within a single display screen (frame), the positive polarity and negative polarity are alternated in a right and left direction and in an up and down direction, and the polarities are reversed for every frame. According to the driving, in the source driver IC
3802
, when the voltage having a positive polarity is outputted via the odd-numbered output terminal for example, the voltage having a negative polarity is outputted via the even-numbered output terminal. In contrast, when the voltage having a negative polarity is outputted via the odd-numbered output terminal, the voltage having a positive polarity is outputted via the even-numbered output terminal.
FIG. 15
exemplifies a driving wave form of the source driver in the dot reverse driving. In
FIG. 15
,
4301
shows the output voltage wave form of the odd-numbered output terminal.
4302
shows the output voltage wave form of the even-numbered output terminal.
4303
shows the voltage of the opposite electrode
3906
. As shown in
FIG. 15
, the voltages showing reverse polarities with respect to the opposite electrode
3906
are always outputted from the odd-numbered output terminal and the even-numbered output terminal, respectively.
FIG. 16
is one example of the block showing a structure of the source driver IC
3802
. Here, the following description only deals with the associated source driver. Note that since a well known gate driver is adopted, the explanation thereof is omitted here. The respective display data (R, G, B) of the digital signal that has been inputted are stored in a sampling memory
4404
in response to a shift register
4403
in a time sharing manner, and then are transmitted to a hold memory
4405
in synchronization with the horizontal synchronizing signal in a lump. The shift register
4403
operates in response to a start pulse and a clock (CK). The data of the hold memory
4405
are sent via a level shifter circuit
4406
to a D/A converter circuit
4407
so as to be converted into analog voltages, respectively. Such analog voltages are sent to an output circuit
4408
from which driving voltages for the gradation display (liquid crystal driving voltages) are outputted via respective liquid crystal output terminals. The respective display data are latched and maintained by the hold memory
4405
for a horizontal synchronizing period. Then, the display data are fetched and latched in synchronization with the next horizontal synchronizing signal.
FIGS.
17
(
a
) and
17
(
b
) are block diagrams exemplifying the output circuit of the source driver IC that carries out the dot reverse driving in accordance with a conventional art (the first conventional art) and showing the operation thereof. In FIGS.
17
(
a
) and
17
(
b
), only the blocks of the respective reference numerals
4405
,
4407
, and
4408
among the circuit elements shown in
FIG. 16
are shown as circuits corresponding to two output terminals.
In FIGS.
17
(
a
) and
17
(
b
),
4501
shows a voltage follower which adopts operational amplifiers and is an output circuit that drives the odd-numbered output terminal.
4502
shows a voltage follower which adopts the same operational amplifiers as those of the voltage follower
4501
and is an output circuit that drives the even-numbered output terminal. Reference numerals
4503
,
4504
,
4505
Fatahi-yar M.
Hjerpe Richard
LandOfFree
Driving apparatus and driving method of liquid crystal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Driving apparatus and driving method of liquid crystal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Driving apparatus and driving method of liquid crystal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3267728